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TZID:Asia/Kolkata
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DTSTART:20240101T000000
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BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20240712T113000
DTEND;TZID=Asia/Kolkata:20240712T123000
DTSTAMP:20260404T181926
CREATED:20240712T060711Z
LAST-MODIFIED:20240803T060918Z
UID:10000013-1720783800-1720787400@aero.iisc.ac.in
SUMMARY:State estimation strategies for space object tracking in the context of space situational awareness
DESCRIPTION:Due to increased human activity in the last two decades\, near-earth space has become congested from functional/non-functional satellites and space debris. These space objects of human origin\, along with natural asteroids and space weather\, pose natural\, accidental\, or intentional threats to functional and expensive satellites. It is imperative to track space assets continuously as well as assess collision threats to take necessary actions\, which is termed Space Situational Awareness (SSA). Assessing the risk of collision of these space debris with active satellites requires estimation of the positions and velocities of both objects. In this talk\, we will briefly discuss some recent advancements in non-linear state estimation techniques – computationally efficient Unscented Kalman Filter and Particle Filter\, and their effectiveness in various space vehicle tracking. We will also examine the possibility of using the underlying efficient uncertainty propagation technique used in these estimators for long-term position uncertainty propagation of a space object. We will then focus on space debris below 10 cm in diameter\, which is difficult to track. In this context\, we will present a Physics Informed Neural Network (PINN)—based approach for estimation of the trajectory of space debris after a collision event between an active satellite and space debris. \n  \nSpeaker: Dr. Sanat K. Biswas \nBiography: Dr. Sanat K. Biswas is an Assistant Professor at IIIT Delhi. He received the B.E. degree from Jadavpur University in 2010\, the M.Tech. degree in Aerospace Engineering from IIT Bombay in 2012\, and a PhD degree in computationally Efficient Unscented Kalman filters for space vehicle navigation from the University of New South Wales (UNSW)\, Sydney\, in 2017. At IIIT Delhi he leads the Space Systems Laboratory and is involved in developing algorithms for Space Situational Awareness\, NavIC reflectometry receiver for remote sensing applications and Precise Point Positioning (PPP) of Low Earth Orbit Satellites. Dr. Biswas serves on the technical committee on Space Communications and Navigation (SCAN)\, and the technical committee on Space Traffic Management (STM) of the International Astronautical Federation. He was the recipient of the 2014 Emerging Space Leaders Grant from the International Astronautical Federation\, the 2019 Early Career Research Award from the Department of Science and Technology\, India and the Young Scientist Award 2020 and 2021 from the International Union of Radio Science (URSI) and 2020 Harry Rowe Mimno Award from the IEEE Aerospace and Electronic Systems Society.
URL:https://aero.iisc.ac.in/event/state-estimation-strategies-for-space-object-tracking-in-the-context-of-space-situational-awareness/
LOCATION:AE Auditorium
CATEGORIES:AE Seminar
ATTACH;FMTTYPE=image/jpeg:https://aero.iisc.ac.in/wp-content/uploads/2024/04/AE-Seminar.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20240716T160000
DTEND;TZID=Asia/Kolkata:20240716T170000
DTSTAMP:20260404T181926
CREATED:20240716T061914Z
LAST-MODIFIED:20240803T062047Z
UID:10000017-1721145600-1721149200@aero.iisc.ac.in
SUMMARY:[PhD Defense] Bearings-Only Quadrotor Guidance in Gap Traversal Scenarios
DESCRIPTION:In autonomous missions\, quadrotors are often required to safely fly through gaps or openings. Designing traversal guidance strategies becomes crucial in such scenarios\, especially when the quadrotor relies on the information obtained through onboard sensors. Lightweight and passive vision-based sensors can readily provide bearing information of the gaps using image features. This thesis addresses the quadrotor guidance problem of traversing gaps using only the relative bearing information. Specifically\, the work considers three scenarios: planar flight through gaps\, window traversal\, and moving gap traversal for lane transition in air corridors. \nThe first part of the thesis presents a planar gap traversal guidance law using bearings-only information. The main contribution in this part is a novel guidance method governing quadrotor heading direction using bearing information of the gap opening. The proposed heading direction is designed using an elliptic shaping angle derived from the angular bisector orientation of the gap-bearing angles. The stability of the resulting closed-loop kinematics is ascertained using Lyapunov’s direct method. Additionally\, a phase plane analysis is carried out to visualize the safe traversal characteristics of the proposed method considering all possible initial conditions around the gap. Combined with a tracking controller\, the proposed guidance strategy is applied to a six-degree-of-freedom (6-DOF) quadrotor model\, ensuring convergence towards the prescribed trajectory. The effectiveness of the proposed guidance method is validated with numerical simulations considering several initial conditions\, noisy bearing measurements\, and dynamic vehicle constraints. \nMoving beyond planar scenarios\, a three-dimensional window traversal problem is considered in the next part of the thesis and a guidance solution is proposed using bearing information of window extremities. The guidance logic governs the commanded flight path angle and heading angle of the vehicle. Again\, these commands comprise an angular bisector component with a shaping angle\, facilitating traversal along a direction normal to the window plane and passing through the centroid. A detailed stability analysis ascertains the convergence of vehicle trajectories to the desired traversal path. Simulation studies consider a 6-DOF quadrotor model\, dynamic attitude constraints\, and noise in bearing information. The robustness of the proposed method is demonstrated through a Monte-Carlo simulation study\, considering various initial conditions and noisy measurements. \nNext\, a new lane transition guidance method for a quadrotor flying in an air corridor system is introduced. Utilizing the bearing information of the neighboring vehicles\, the guidance method directs the quadrotor for a safe transition between two lanes. Comprising three sequential guidance phases\, the method includes discerning guidance for determining neighboring vehicle velocity\, longitudinal guidance to identify suitable gaps in the destination lane\, and transit guidance to maneuver the quadrotor into the desired gap. A detailed analysis deduces\, in closed-form\, the time duration for each of the three guidance phases. Additionally\, local asymptotic stability is ascertained for the proposed guidance phases. Simulation results and Monte-Carlo studies demonstrate the proposed method’s feasibility\, effectiveness\, and robustness for safe autonomous lane transition. \nOverall\, the proposed guidance methods present simple\, easily computable and closed-form analytic guidance inputs using only the passive bearing information. Further\, deterministic performance guarantees provide a sound theoretical foundation for the novel guidance solutions. The thesis also includes representative experimental studies using an indoor motion capture system and Crazyflie quadrotor platform. \n  \n  \nSpeaker: Midhun E K
URL:https://aero.iisc.ac.in/event/phd-defense-bearings-only-quadrotor-guidance-in-gap-traversal-scenarios/
LOCATION:STC Seminar Hall\, Dept. of Aerospace Engineering
CATEGORIES:Thesis Colloquium / Defence
ATTACH;FMTTYPE=image/jpeg:https://aero.iisc.ac.in/wp-content/uploads/2024/04/Thesis-Colloquium-Defence.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20240719T103000
DTEND;TZID=Asia/Kolkata:20240719T233000
DTSTAMP:20260404T181926
CREATED:20240719T061638Z
LAST-MODIFIED:20240803T061806Z
UID:10000016-1721385000-1721431800@aero.iisc.ac.in
SUMMARY:On mathematical analysis of biomembrane structures
DESCRIPTION:During the cellular processes\, membrane instabilities play a crucial role across the several domains of life. In many cases\, this is aided by evolutionary molecular complexes. For example\, the complex contains protein monomers that adhere to the cell membrane and polymerize into thin filaments\, which proceed to form a helical constricting bundle\, eventually leading to the cleavage of the neck during cell division; the exact mechanism by which the helical filament induces curvature in the membrane is poorly understood. Recently\, we explored the mechanics of membrane and filament coupling through a continuum model for both structures and presented computational strategies to solve the highly nonlinear model. In an ongoing work\, we model a similar phenomenon associated with particles and use linear stability analysis to predict the onset of certain instabilities in the case when proteins are modeled as embedded particles. A part of this research is under current investigation using both numerical techniques as well as tools of local nonlinear analysis of bifurcating branches. \nSpeaker: Prof. Basant Lal Sharma \nBiography: Prof. Basant Lal Sharma received a Bachelor of Technology in Mechanical Engineering from the Indian Institute of Technology Bombay\, Powai\, Mumbai\, India\, in 1999. In 2004\, he received a Ph.D. in Mechanics (P. Rosakis) from Cornell University\, Ithaca\, NY\, USA. After post-doctoral positions at Cornell University (S.H. Strogatz) and École Polytechnique\, Palaiseau\, Paris\, France (L. Truskinovsky)\, he joined the Department of Mechanical Engineering\, Indian Institute of Technology Kanpur in January 2007 as a Faculty member.
URL:https://aero.iisc.ac.in/event/on-mathematical-analysis-of-biomembrane-structures/
LOCATION:STC Seminar Hall\, Dept. of Aerospace Engineering
CATEGORIES:AE Seminar
ATTACH;FMTTYPE=image/jpeg:https://aero.iisc.ac.in/wp-content/uploads/2024/04/AE-Seminar.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20240731T150000
DTEND;TZID=Asia/Kolkata:20240731T160000
DTSTAMP:20260404T181926
CREATED:20240731T054804Z
LAST-MODIFIED:20240822T084630Z
UID:10000012-1722438000-1722441600@aero.iisc.ac.in
SUMMARY:[MTech(Res) Colloquium] Deformation-based Topological Lattices and their Edge States
DESCRIPTION:Topological elastic metamaterials (TEMs) represent a novel class of elastic materials known for their unique ability to localize vibration energy at boundaries\, maintaining robustness against system disorders. These unconventional properties make TEMs highly attractive for applications in vibration isolation\, energy harvesting\, mechanical sensing\, and waveguiding.\n\n\nSpring-mass models are fundamental in designing TEMs\, capturing essential physics due to their structure of periodically repeating unit cells with lumped masses. The elastic coupling of these unit cells gives rise to unique wave propagation properties within the bulk material. Traditionally\, TEMs have been analyzed using mass displacements as degrees of freedom. However\, recent discoveries have shown that analyzing these models through the lens of spring deformations as degrees of freedom opens up new design possibilities for TEMs.\n\n\nIn this study\, we generalize the deformation framework in one dimension (1D). We introduce a novel 1D TEM that employs spinners with alternating moments of inertia coupled to their nearest neighbors through various types of spring connections. These connections result in different spring deformations\, thereby extending the deformation framework. Notably\, different localization profiles of boundary states emerge at opposite ends of the finite model\, explained by hidden chiral symmetry in the deformation framework. The results are validated experimentally using Laser Doppler Vibrometry. We further extend the deformation framework to two dimensions (2D) using a quasi-1D approach\, demonstrating the robustness of boundary waves against disorder.\n\n\nWe then explore the mathematical foundations of the deformation framework for a general 1D lattice\, revealing an underlying rank deficiency in the local stiffness matrices of spring-mass models. This leads to a unique factorization of the global stiffness matrix\, allowing the model to be represented in the deformation framework as an isospectral partner. We illustrate the utility of this approach with examples of spring-mass models for bars and beams\, generating a family of isospectral partners exhibiting disorder and boundary states.\n\n\nOur study introduces a non-standard approach to expressing the dynamics of spring-mass models of TEMs\, unlocking numerous research opportunities to construct periodic and aperiodic topological systems with a broader range of boundary conditions. Additionally\, the insights gained from this work can be extended to other classical domains\, such as acoustic\, photonic\, and electrical systems.\n  \n  \n\nSpeaker: UDBHAV VISHWAKARMA
URL:https://aero.iisc.ac.in/event/mtechres-colloquium-deformation-based-topological-lattices-and-their-edge-states/
LOCATION:STC Seminar Hall\, Dept. of Aerospace Engineering
CATEGORIES:Thesis Colloquium / Defence
ATTACH;FMTTYPE=image/jpeg:https://aero.iisc.ac.in/wp-content/uploads/2024/04/Thesis-Colloquium-Defence.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20240801T103000
DTEND;TZID=Asia/Kolkata:20240801T113000
DTSTAMP:20260404T181926
CREATED:20240801T054703Z
LAST-MODIFIED:20240803T054737Z
UID:10000011-1722508200-1722511800@aero.iisc.ac.in
SUMMARY:[PhD Colloquium] Development of Generalizable Spiking Neural Network-based Learning Frameworks for Solving Perimeter Defense Problem
DESCRIPTION:Spiking Neural Networks (SNNs) are third-generation neural networks that can process information in a more biologically realistic way compared to other neural networks such as sigmoidal networks. They process the information in terms of spike which is considered as a discrete event in time. Due to their high energy efficiency\, SNNs are used in various applications such as classification\, prediction\, assignment\, recognition\, etc. In this thesis\, the capability of SNNs to solve the SpatioTemporal MultiTask Assignment (STMTA) problem which is formulated from a Perimeter Defense Problem (PDP) is explored. \nDue to the efficiency of SNNs in handling spatiotemporal data\, they are used to develop learning-based frameworks to solve the PDP. Initially\, a time-varying weight SNN for decentralized assignment learning for a critical PDP is presented in this thesis. A Decentralized sequential Assignment Learning with Spiking neural networks (abbreviated as DeALS) approach is proposed for the PDP which can approximate the relation between intruder velocity\, shape of the territory\, size of the defender team\, and protection area. In DeALS\, a multitask assignment SNN is developed for each defender to protect the perimeter. This time-varying weight multitask assignment SNN is trained in a supervised manner to approximate the ground truth obtained from the existing external solution for PDP. To reduce the usage of external ground truth algorithms the greedy assignment learning-based frameworks are developed to solve PDP in a decentralized manner. Due to the decentralized training of SNN\, conflicts are found in the final defender assignments. Therefore to resolve this conflicts an additional conflict-free trajectory generation algorithm is used. Further\, in the thesis to reduce the usage of a conflict-free trajectory generation algorithm an SNN which can generate conflict-free assignments is developed to solve PDP. A centralized greedy assignment learning solution is developed for PDP using the aforementioned conflict-free assignment SNN. These conflict-free assignments are obtained with the help of inhibitory connections among the assignment neurons in the SNN. \nFurther\, the inhibitory connections are used to develop efficient deep SNNs for classification purposes. The inhibitory connections are motivated by biology. These inhibitory connections make sure that the first spiking neurons in a layer acquire knowledge efficiently about the input by inhibiting the response of other neurons in the same layer. A Distributed Coding SNN (DC-SNN) architecture with inhibitory connections in the hidden layer is developed for solving classification problems. With the help of Temporal Separation Modulated Spike Timing Dependent Plasticity (TSM-STDP) learning it is demonstrated that a DC-SNN is suitable for early interruption which helps in faster classification. Eventually\, in this thesis\, SNN classifiers with time-varying weights without hidden layers are developed which are capable of inherent interpretations. The time-varying weights are modeled using random Gaussian mixtures spread across the simulation interval.  By establishing relationships between the amplitudes of time-varying weights and the spike patterns of the neurons in the architecture\, the decisions of these spiking neural classifiers are interpreted. \n  \nSpeaker: P. Mohammed Thousif
URL:https://aero.iisc.ac.in/event/phd-colloquium-development-of-generalizable-spiking-neural-network-based-learning-frameworks-for-solving-perimeter-defense-problem/
LOCATION:STC Seminar Hall\, Dept. of Aerospace Engineering
CATEGORIES:Thesis Colloquium / Defence
ATTACH;FMTTYPE=image/jpeg:https://aero.iisc.ac.in/wp-content/uploads/2024/04/Thesis-Colloquium-Defence.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20240823T160000
DTEND;TZID=Asia/Kolkata:20240823T170000
DTSTAMP:20260404T181926
CREATED:20240822T090144Z
LAST-MODIFIED:20240822T090919Z
UID:10000018-1724428800-1724432400@aero.iisc.ac.in
SUMMARY:Recent Advances in Infrared Optics: From Metalenses to Upconversion  Imaging
DESCRIPTION:Infrared imaging and spectroscopic sensing are strategic technologies with diverse applications in defense\, space\, industrial monitoring\, medical diagnosis and treatment. Advancements in infrared sensing technology over the years has relied on key developments in light sources\, detectors\, optical components and image processing techniques. However\, the high costs of infrared coherent light sources\, poor performance of cooled focal plane-arrays\, and use of exotic materials for building lenses\, filters\, polarizers etc. has been a deterrent in finding widespread use for this technology. There is an ongoing effort worldwide to realize high-performance yet\, practically relevant optical hardware solutions for infrared sensing and imaging. In this talk\, I will give an overview of this field drawing on personal pain points working on the applications. I will also discuss in detail three key developments in this area\, namely: (i) small foot-print metalenses for building lowcost infrared imaging systems\, (ii) high-performance\, resonant metasurfaces as wavelength selective filters for multispectral applications\, and (iii) up-conversion imaging as an alternative for direct infrared detection by converting infrared photons to the visible range for detection using high performance silicon sensors. \nSpeaker: Prof. Varun Raghunathan \nBiography: Varun Raghunathan is an Associate Professor at the ECE department\, Indian Institute of Science\, Bangalore\, India. His research group works broadly in the area of experimental optics with interest in nonlinear optics\, integrated nanophotonics\, biophotonics\, optical and quantum communications. He obtained his Ph.D. degree in electrical engineering from the University of California Los Angeles\, Los Angeles\, CA\, USA\, in 2008\, working on silicon photonics. From 2009 to 2012\, he was a Postdoctoral Scholar with the Department of Chemistry\, University of California Irvine\, Irvine\, CA\, USA\, working in the area of nonlinear optical microscopy. He was also Research Scientist with Agilent Research Laboratories\, Santa Clara\, CA\, USA from 2012 to 2016\, working in the areas of infrared micro-spectroscopy with applications of novel optical sensing techniques in digital pathology.
URL:https://aero.iisc.ac.in/event/recent-advances-in-infrared-optics-from-metalenses-to-upconversion-imaging/
LOCATION:Auditorium (AE 005)\, Department of Aerospace Engineering
CATEGORIES:AE Seminar
ATTACH;FMTTYPE=image/jpeg:https://aero.iisc.ac.in/wp-content/uploads/2024/04/AE-Seminar.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20240826T150000
DTEND;TZID=Asia/Kolkata:20240826T160000
DTSTAMP:20260404T181926
CREATED:20241118T084323Z
LAST-MODIFIED:20241118T084323Z
UID:10000019-1724684400-1724688000@aero.iisc.ac.in
SUMMARY:Guidance for Pursuit and Evasion
DESCRIPTION:Traditional pursuit-evasion engagements are concerned with a single pursuer chasing a single target. Current and future engagements may include more than two adversaries. In my talk I will present some new guidance concepts we developed for: 1-on-1\, N-on-1\, 1-on-N\, and N-on-M engagements. Special emphasis will be given to the underlying geometrical rules for guidance as well as to the presentation and analysis of some interesting cooperative guidance schemes. \nSpeaker: Prof. Tal Shima \nBiography: Tal Shima received his B.Sc.\, MA\, and Ph.D. degrees\, all in Aerospace Engineering\, from the Technion – Israel Institute of Technology. He also received the MBA degree from the Tel-Aviv University. Since 2006 Dr. Shima is with the Department of Aerospace Engineering at the Technion where he currently holds the Lottie and Max Dresher Chair in Aerospace Performance and Propulsion. He recently finished his 4 years’ term as dean of the department. His current research interests are in the area of guidance of autonomous vehicles\, especially aerial ones\, operating individually or as a team. He is the author/co-author of more than 100 archival journal papers in these research areas.
URL:https://aero.iisc.ac.in/event/guidance-for-pursuit-and-evasion/
LOCATION:Auditorium (AE 005)\, Department of Aerospace Engineering
CATEGORIES:AE Seminar
ATTACH;FMTTYPE=image/jpeg:https://aero.iisc.ac.in/wp-content/uploads/2024/04/AE-Seminar.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20240910T153000
DTEND;TZID=Asia/Kolkata:20240910T163000
DTSTAMP:20260404T181926
CREATED:20241118T094224Z
LAST-MODIFIED:20241118T094224Z
UID:10000020-1725982200-1725985800@aero.iisc.ac.in
SUMMARY:Solutions for Reducing Severity in Aircraft Flat-Spin Recovery
DESCRIPTION:Aircraft spin is special category of stall and defined as an autorotation in a downward helical pattern with a higher yaw rate than roll and pitch rate. Among the various modes of aircraft spin\, flat-spin being the most ruthless form and characterized by a high angle of attack (𝛼) in the range of 65° to 90°. The flat spin is particularly dangerous since the efficiency of aerodynamic control surfaces is greatly diminished due to nearly perpendicular airflow. In this seminar\, I will talk about\, different flight dynamic and control-based solutions that I developed for recovery (1. Recovery Using Primary Control Surfaces\, 2. Recovery Using Optimally Deflected Deployable Fin\, 3. Strategic Thrust Vector Control Based Recovery\, 4. Vertical Thrust Based Recovery\, 5. Recovery Satisfying Aerodynamic and Load Factor Constraints\, 6. Recovery Using Model Predictive Control\, and 7. Decoupled Incremental Nonlinear Dynamic Inversion Control for Recovery) to reduce the fatality of the flat-spin in terms of excessive altitude loss regulating the survivability post aircraft recovery. Moreover\, an investigation is performed on how the wind and wind share impact the recovery profile. The flat-spin recovery profile is demonstrated on a mathematical model of F-18 high alpha research vehicle (HARV) to test the efficacy of the proposed methods. \nSpeaker: Dr. Salahudden \nBiography: Dr. Salahudden is currently working as an Assistant Professor at the Department of Aerospace Engineering (AE) at Punjab Engineering College\, Chandigarh\, India. Before this\, he was the Deputy Manager in Flight Controls Department at TATA Aerospace and Defence. Prior to that\, he worked as a Postdoctoral Fellow at Auburn University in the AE Department\, United States. He earned a Ph.D. in AE from the Indian Institute of Technology Kanpur (IITK)\, India\, in 2022. He received a M.Tech in AE from IIT Kanpur in 2018 and a B.Tech in AE from SRM University Chennai\, India in 2016. His research interests include the areas of flight mechanics\, aircraft dynamics\, aircraft design\, control law design for flight vehicles\, aircraft simulator design\, and autopilot design. He published numerous reputable journals and conferences based on his research. He is also serving as a reviewer for several reputed journals. He has received many academic and research awards\, such as Outstanding PhD Thesis Award\, Excellent Undergraduate Project Award\, and Outstanding Academic Performance Award.
URL:https://aero.iisc.ac.in/event/solutions-for-reducing-severity-in-aircraft-flat-spin-recovery/
LOCATION:Auditorium (AE 005)\, Department of Aerospace Engineering
CATEGORIES:AE Seminar
ATTACH;FMTTYPE=image/jpeg:https://aero.iisc.ac.in/wp-content/uploads/2024/04/AE-Seminar.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20240917T153000
DTEND;TZID=Asia/Kolkata:20240917T163000
DTSTAMP:20260404T181926
CREATED:20241118T094538Z
LAST-MODIFIED:20241118T094538Z
UID:10000021-1726587000-1726590600@aero.iisc.ac.in
SUMMARY:Advanced Mission Architectures for Long-term Exploration of Mars\, Venus\, and Beyond
DESCRIPTION:The increasing complexity of future space exploration roadmaps calls for novel mission architectures\, integrated mission analysis\, and systems engineering frameworks to inform early decision-making and technological innovation. In this talk\, I will discuss the mission architecture and analysis of two multi-decade campaigns: (1) human missions to Mars\, and (2) astrobiology-driven missions to Venus. First\, I will present the orbital design considerations and results for Mars Spacedock\, an orbital platform for sustainable human exploration. A system-level optimization incorporates discreet mission constraints and comprehensive analysis across all the mission phases from interplanetary trajectories to entry\, descent\, and landing (EDL). Surface accessibility from candidate orbits is obtained by implementing constant bank angle control during EDL. Next\, I will discuss the mission design for a series of missions to Venus searching for signs of life in the clouds. I will highlight the early trade-offs between objectives and operational constraints for a balloon platform and a sample return mission. A focal point will be the Venus ascent vehicle design for sample return through launch trajectory optimization. Additionally\, I will briefly discuss ongoing experiments to establish the feasibility of instruments for in situ analysis of sulfuric acid clouds. Finally\, I will discuss my future research plans in mission design\, systems engineering\, and innovative small-scale spacecraft testing platforms for advanced technologies such as GNC during proximity operations.   \nSpeaker: Dr. Rachana Agarwal \nBiography: Rachana Agrawal is currently a Postdoctoral Associate in the Earth\, Atmospheric and Planetary Sciences department with Prof. Sara Seager at MIT. She is leading mission design and instrumentation projects for astrobiology-focused missions to Venus. She obtained her PhD from the School of Aeronautics and Astronautics at Purdue University under the supervision of Prof. James Longuski and Prof. Sarag Saikia. Her PhD work focused on the design and analysis of an orbital logistics architecture for the sustainable human exploration of Mars. She is broadly interested in robotic and human space mission engineering with current focus on mission analysis\, systems engineering\, and technological innovation and development.
URL:https://aero.iisc.ac.in/event/advanced-mission-architectures-for-long-term-exploration-of-mars-venus-and-beyond/
LOCATION:Online
CATEGORIES:AE Seminar
ATTACH;FMTTYPE=image/jpeg:https://aero.iisc.ac.in/wp-content/uploads/2024/04/AE-Seminar.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20241001T153000
DTEND;TZID=Asia/Kolkata:20241001T163000
DTSTAMP:20260404T181926
CREATED:20241118T095302Z
LAST-MODIFIED:20241118T095302Z
UID:10000023-1727796600-1727800200@aero.iisc.ac.in
SUMMARY:Shape control and programmable morphing: applications to biological and bio-inspired motility
DESCRIPTION:In recent years\, we have studied morphing and shape control problems in the context of motility of biological systems and locomotion of robotic systems. Our aim is to distil lessons useful for the design of innovative and bio-inspired medical and devices. The tools used for this purpose include theoretical/computational mechanics of solids and fluids\, physical experimentation and manufacturing of prototypes\, and observations at the microscope in the case of unicellular swimmers. \nSome of the insights that have emerged from this research line are reviewed in this talk\, with special emphasis on unicellular swimmers\, both flagellates and ciliates\, and on attempts to produce bio-inspired artifacts mimicking their capabilities using active materials such as liquid crystal elastomers. As examples of applications\, we discuss fabrication and modelling of LCE-based fiber arrays realizing artificial active cilia carpets [1] and light-powered LCE-based medusoid swimmers [2]\, see Figure 1 below. \n  \nSpeaker: Prof. Antonio DeSimone \nBiography: Prof. Antonio DeSimone is a professor of Structural Mechanics at SISSA in Trieste and the BioRobotics Institute at Scuola Superiore Sant’Anna in Pisa. His research interests span a wide range of topics\, including the mechanics of materials\, micromagnetics\, systems biology\, and the calculus of variations. He has held numerous visiting research appointments\, including positions at the University of Minnesota\, Université Paris XIII\, the Joliot-Curie Chair at ESPCI Paris\, the Institute for Mathematics and its Applications in Minneapolis\, and the Isaac Newton Institute for Mathematical Sciences in Cambridge. In recognition of his contributions to the mathematical sciences\, he was awarded the Keith Medal in 2006.
URL:https://aero.iisc.ac.in/event/shape-control-and-programmable-morphing-applications-to-biological-and-bio-inspired-motility/
LOCATION:Auditorium (AE 005)\, Department of Aerospace Engineering
CATEGORIES:AE Seminar
ATTACH;FMTTYPE=image/jpeg:https://aero.iisc.ac.in/wp-content/uploads/2024/04/AE-Seminar.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20241024T110000
DTEND;TZID=Asia/Kolkata:20241024T120000
DTSTAMP:20260404T181926
CREATED:20241118T094855Z
LAST-MODIFIED:20241118T095402Z
UID:10000022-1729767600-1729771200@aero.iisc.ac.in
SUMMARY:Bandgap Formation Mechanisms in Phononic Crystals with Square Bravais Lattice
DESCRIPTION:The engineered periodic structures\, known as phononic crystals\, exploit variations in geometric design to achieve distinct impedance contrasts\, thereby controlling wave propagation characteristics. These materials can effectively attenuate acoustic waves across a broad range of frequencies. The band structure of these metamaterials\, which dictates the range of frequencies over which wave propagation is prohibited\, is heavily influenced by the geometry\, mechanical properties\, and the symmetry group of the phononic crystal. The presence of higher symmetries often correlates with the emergence of complete omnidirectional bandgaps (BGs) — frequency ranges where waves of all polarizations attenuate exponentially due to mechanisms such as Bragg scattering\, local resonances\, or their combination. \nIn this work\, we calculate the band structures of p4\, p4mm and p4gm phononic crystals for real and imaginary Bloch wavevectors to understand the mechanisms behind the BG formation. We evaluate the BG’s attenuation properties by analyzing the real eigenvalues of the imaginary Bloch wavevectors\, which provide measurable evidence of the waves’ exponential decay. Furthermore\, we conduct experimental and numerical measurements of transmission loss for both P- and S-waves via finite crystals\, confirming the superior attenuation facilitated by the coupling of the Bragg and resonance BG mechanisms. This research validates the correlation between the measured transmission loss and the theoretically predicted evanescent modes within the BGs. \nSpeaker: Prof. Pavel I. Galich \nBiography: Pavel I. Galich\, PhD\, is an Assistant Professor at the Technion – Israel Institute of Technology\, where he leads the Wave Mechanics and Metamaterials Laboratory within the Faculty of Aerospace Engineering. He earned his PhD from the Technion\, AE and his MSc and BSc in Applied Mathematics and Physics from the Moscow Institute of Physics and Technology\, both with honors. His research interests focus on acoustic metamaterials\, wave propagation in non-linear materials\, and advanced composites for aerospace applications. Pavel has published extensively in high-impact journals and has presented his work at numerous international conferences.
URL:https://aero.iisc.ac.in/event/bandgap-formation-mechanisms-in-phononic-crystals-with-square-bravais-lattice/
LOCATION:AE Auditorium
CATEGORIES:AE Seminar
ATTACH;FMTTYPE=image/jpeg:https://aero.iisc.ac.in/wp-content/uploads/2024/04/AE-Seminar.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20241024T150000
DTEND;TZID=Asia/Kolkata:20241024T170000
DTSTAMP:20260404T181926
CREATED:20241024T043037Z
LAST-MODIFIED:20241121T062124Z
UID:10000026-1729782000-1729789200@aero.iisc.ac.in
SUMMARY:Learning stable and accurate numerical schemes for LES applications
DESCRIPTION:Deep neural network machine learning models have demonstrated success in addressing time-dependent Partial Differential Equations (PDEs\, e.g.\, Physics Informed Neural Networks or PINNs and mesh graph network models by Google DeepMind). Yet\, these network models encounter two significant challenges: \n(1) generalisation to problems beyond their training data and (2) numerical instability during long-time evolutions. \nIn this talk a new spectral framework based on a local error analysis  is presented to design and optimize numerical methods for convection problems called Local Transfer Analysis (LTA). LTA converts traditional numerical discretisation to a network of impedance blocks where parameters can be introduced to tune the local block impedance. Such a network’s impedance can be tuned using a Deep Graph Network that predicts optimal values for the parameters that lead to matched impedance. This allows locally tuned traditional numerical schemes that do not suffer from stability problems\, at the same time generalises to a widerange of problems outside of training on unstructured meshes outperforming the unoptimised scheme. Application of the framework to tune and optimise the Two-step Taylor Galerkin scheme (TTGC) used extensively in CERFACS for Combustion LES problems is presented for linear convection\, inviscid Burgers’ and Euler equations on unstructured meshes. \n\nSpeaker:Dr. Pavanakumar Mohanamuraly \nBiography: \nDr. Pavanakumar Mohanamuraly currently serves as a Senior Researcher at the ALGO-COOP Team\, CERFACS\, Toulouse\, France. He has extensive experience in CAD-based Aerodynamics Shape Optimisation\, adjoint sensitivity analysis\, Machine Learning\, and high-performance computing\, and brings a wealth of knowledge and practical experience in algorithmic differentiation applied to parallel codes. He holds a PhD in Aerospace Engineering from Queen Mary University of London and an MS in Aerospace Engineering from Pennsylvania State University. His career includes \nroles at Integrated Test Range\, DRDO\, Balasore\, Honeywell Technology Solutions\, Bangalore\, National Aerospace Laboratories\, India\, Airbus Group\, Bangalore. His work has significantly contributed to the advancement of computational methods in CERFACS\, particularly in the areas of hybrid CFD and machine learning and parallel adaptive mesh refinement and exascale load-balancing problems.
URL:https://aero.iisc.ac.in/event/learning-stable-and-accurate-numerical-schemes-for-les-applications/
LOCATION:AE Auditorium
CATEGORIES:AE Seminar
ATTACH;FMTTYPE=image/jpeg:https://aero.iisc.ac.in/wp-content/uploads/2024/10/Reconstruction-Era-and-the-Gilded-Age-History-11th-Grade-Red-Variant-by-Slidesgo-1.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20241030T150000
DTEND;TZID=Asia/Kolkata:20241030T170000
DTSTAMP:20260404T181926
CREATED:20241030T093004Z
LAST-MODIFIED:20241126T093945Z
UID:10000028-1730300400-1730307600@aero.iisc.ac.in
SUMMARY:Ph.D. (Engg): Intersection Planning in Multilane Aerial Corridors for UAVs
DESCRIPTION:Uncrewed aerial vehicles (UAVs) are revolutionizing traditional aviation markets by opening the airspace to new participants and expanding multimodal applications\, increasing the UAVs’ participation in the uncontrolled low-altitude class G airspace. Therefore\, having a UAV Traffic Management (UTM) system is of great importance in designing structured traffic rules for UAV paths in the airspace (corridors) and intersections. This work addresses the problem of intersection planning in the context of UTM. We consider a multilane multi-UAV traffic management framework\, CORRIDRONE. In this setup\, an intersection volume is defined when two or more multilane corridors merge in the airspace. Unlike road intersection scenarios\, an aerial intersection has a virtual\, non-visible boundary. Hence\, resolving conflicts is challenging without a traffic light. In this thesis\, we develop algorithms to manage intersections and resolve conflicts in pre-flight and in-flight modes. In the first part of the thesis\, we consider that only one UAV is assigned per corridor. Hence\, intersection volumes are created by intersecting two lanes. Here\, we present an algorithm that exploits the relative geometry between the UAVs and schedules the speed of one UAV relative to the other for multiple intersections. Next\, we extend this methodology to pre-plan a UAV trajectory also to include UAV accelerations while scheduling. This method utilizes the time taken for the UAVs involved in the conflict to enter and exit an intersection formed owing to their corridor paths. For corridors with multiple lanes\, we define an intersection volume free of lanes\, such that the lane boundaries are valid only till the intersection boundaries. We then present a lane-changing approach to resolve conflicts by changing the initially intended path connecting two lanes. We further added security to the UAVs in conflict-laden scenarios by creating a dronecage\, which is an amalgamation of multiple geofences intersecting at multiple points (intercrosses). The UAVs travel inside these geofences to change lanes or corridors and reach their destination safely. We propose an algorithm that uses an approach vector-based strategy to navigate this dronecage. We show the effectiveness of the algorithms developed with numerical simulations and hardware tests. The motivation behind the thesis lies in providing the complete conflict resolution architecture for UTM to be used if and when needed in real-life scenarios. \nSpeaker: Samiksha Rajkumar Nagrare \nResearch Supervisor: Debasish Ghose
URL:https://aero.iisc.ac.in/event/intersection-planning-in-multilane-aerial-corridors-for-uavs/
LOCATION:STC Seminar Hall\, Dept. of Aerospace Engineering
CATEGORIES:Thesis Colloquium / Defence
ATTACH;FMTTYPE=image/jpeg:https://aero.iisc.ac.in/wp-content/uploads/2024/11/samiksha.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20241108T150000
DTEND;TZID=Asia/Kolkata:20241108T170000
DTSTAMP:20260404T181926
CREATED:20241108T093028Z
LAST-MODIFIED:20241126T093831Z
UID:10000029-1731078000-1731085200@aero.iisc.ac.in
SUMMARY:MTech(Res): Deformation-based Topological Lattices and their Edge States
DESCRIPTION:Topological elastic metamaterials (TEMs) represent a novel class of elastic materials known for their unique ability to localize vibration energy at boundaries\, maintaining robustness against system disorders. These unconventional properties make TEMs highly attractive for applications in vibration isolation\, energy harvesting\, mechanical sensing\, and waveguiding. \nSpring-mass models are fundamental in designing TEMs\, capturing essential physics due to their structure of periodically repeating unit cells with lumped masses. The elastic coupling of these unit cells gives rise to unique wave propagation properties within the bulk material. Traditionally\, TEMs have been analyzed using mass displacements as degrees of freedom. However\, recent discoveries have shown that analyzing these models through the lens of spring deformations as degrees of freedom opens up new design possibilities for TEMs. \nIn this study\, we generalize the deformation framework in one dimension (1D). We introduce a novel 1D TEM that employs spinners with alternating moments of inertia coupled to their nearest neighbors through various types of spring connections. These connections result in different spring deformations\, thereby extending the deformation framework. Notably\, different localization profiles of boundary states emerge at opposite ends of the finite model\, explained by hidden chiral symmetry in the deformation framework. The results are validated experimentally using Laser Doppler Vibrometry. We further extend the deformation framework to two dimensions (2D) using a quasi-1D approach\, demonstrating the robustness of boundary waves against disorder. \nWe then explore the mathematical foundations of the deformation framework for a general 1D lattice\, emphasizing an underlying rank deficiency in the local stiffness matrices of spring-mass models. This leads to a special factorization of the global stiffness matrix that involves trapezoidal matrices\, thereby allowing the model to be represented in the deformation framework as an isospectral partner. We illustrate the utility of this approach with examples of disordered topological models\, generating a family of isospectral partners exhibiting boundary states and bandgaps. \nOur study introduces a non-standard approach to expressing the dynamics of spring-mass models of TEMs\, unlocking numerous research opportunities to construct periodic and aperiodic topological systems with a broader range of boundary conditions. Additionally\, the insights gained from this work can be extended to other classical domains\, such as acoustic\, photonic\, and electrical systems. \n  \nSpeaker: Udbhav Vishwakarma \nResearch Supervisor: Rajesh Chaunsali
URL:https://aero.iisc.ac.in/event/deformation-based-topological-lattices-and-their-edge-states/
LOCATION:STC Seminar Hall\, Dept. of Aerospace Engineering
CATEGORIES:Thesis Colloquium / Defence
ATTACH;FMTTYPE=image/jpeg:https://aero.iisc.ac.in/wp-content/uploads/2024/11/Udbhav-Vishwakarma1.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20241114T140000
DTEND;TZID=Asia/Kolkata:20241114T170000
DTSTAMP:20260404T181926
CREATED:20241114T083023Z
LAST-MODIFIED:20241126T093958Z
UID:10000030-1731592800-1731603600@aero.iisc.ac.in
SUMMARY:Ph.D. (Engg): Asymptotic Modelling of Carbon Nanotube (CNT) and CNT-Reinforced Composite Structures Using Strain Gradient Formulations
DESCRIPTION:Carbon nanotubes (CNTs) have garnered attention for their remarkable mechanical\, thermal\, and electrical properties\, making them valuable in various applications. CNTs are particularly advantageous in aerospace structures as reinforcements in polymer matrix composites\, enhancing structural performance while reducing weight. Furthermore\, they offer the potential for multifunctionality\, integrating structural\, thermal\, and electrical functionalities within components like wings. However\, accurately modelling CNT behaviour poses challenges\, especially considering their application in larger-scale aerospace structures. While accurate\, molecular dynamics and molecular structural mechanics are computationally intensive and limited in length scale. In this context\, the present research proposes reduced-order continuum structural models using the Variational Asymptotic Method (VAM) to study CNT and its composite structures while incorporating length-scale effects using strain-gradient formulations. \nUsing VAM\, single-walled CNTs (SWCNTs) were first analysed by considering them as straight\, hollow\, circular tubes in a local continuum framework. This tube model accounts for the geometrically-nonlinear behaviour of standalone CNT when subjected to bending and buckling loads. Cross-sectional ovalisation leading to nonlinear bending and buckling behaviour has been studied. Combined loading cases of bending and compression; torsion and compression; & bending and torsion have been examined. The study aims to provide insights into the 3-D nonlinear deformation behaviour of SWCNTs\, offering a more efficient approach for evaluating CNTs in aerospace composite applications. \nIn the next step\, recognising the significance of the structure’s small size (such as used in MEMS\, NEMS\, and sensors)\, non-classical theories\, such as the Modified Strain Gradient Theory\, which account for the size effect in the material\, have been employed to develop a pioneering beam and plate models tailored for CNT-reinforced composite structures. Emphasising the critical nature of size effects\, characterised by length-scale parameters\, this study delves into the nuances of the length-scale effects in nanoscale structures. To develop the asymptotically-correct strain-gradient beam model\, a prismatic beam with a rectangular cross section has been considered to derive zeroth-order and subsequent higher-order models while capturing the strain-gradient effects. Notably\, this work is the first application of non-classical theories in developing VAM-based beam models. Different orders for length-scale parameters have been considered\, and the validity of each choice is scrutinised\, followed by guidance on the appropriate choice of the length-scale parameters. \nFollowing the development of the strain-gradient beam model\, a modified strain gradient theory-based plate model has also been developed using VAM\, which is again a first-of-its-kind work in the context of VAM and reduced-order structural models. Using the variational methods\, fourth-order differential equations were obtained for the non-classical case\, and similarly\, an additional set of boundary conditions (non-classical) were also derived. The warping solutions and the plate stiffnesses are obtained by solving this boundary value problem. It was noted that the material length-scale parameters appear only in the bending and twist stiffness terms. Further\, the classical results can be derived by setting the material length-scale parameters to zero. Zeroth- and first-order approximations have been derived\, followed by detailed validation of the results with literature for bending and buckling load cases. Parametric studies involving variations in thickness and plate width have been conducted to assess their influence on mechanical behaviour. The developed plate model is then applied to CNT-reinforced composites\, and their bending and buckling studies have been carried out. The parametric studies have also considered evaluating all influencing parameters like CNT volume fraction\, material length-scale parameter\, plate thickness and width. \n  \nSpeaker: Renuka Sahu \nResearch advisor: Prof Dineshkumar Harursampath
URL:https://aero.iisc.ac.in/event/asymptotic-modelling-of-carbon-nanotube-cnt-and-cnt-reinforced-composite-structures-using-strain-gradient-formulations-2/
LOCATION:STC Seminar Hall\, Dept. of Aerospace Engineering
CATEGORIES:Thesis Colloquium / Defence
ATTACH;FMTTYPE=image/jpeg:https://aero.iisc.ac.in/wp-content/uploads/2024/11/renuka.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20241127T110000
DTEND;TZID=Asia/Kolkata:20241127T130000
DTSTAMP:20260404T181926
CREATED:20241126T094710Z
LAST-MODIFIED:20241126T094710Z
UID:10000032-1732705200-1732712400@aero.iisc.ac.in
SUMMARY:Ph.D. (Engg): On the nature of transonic buffet in a finite span wing
DESCRIPTION:Transonic buffet\, or shock oscillations\, is a pre-stall aerodynamic instability\, caused by shock boundary layer interaction\, of the flow over a wing. This aerodynamic instability occurs at critical combinations of transonic Mach number and angle of attack. Shock oscillations cause vibrations of the wing and is known as buffeting. Buffeting may cause fatigue of the wing\, and in an overall sense limit the flight envelope of the aircraft. Despite decades of study\, an unequivocal understanding of the physical mechanism of transonic buffet is lacking. In literature\, global stability analysis\, modal analysis\, and spatial correlation-based wave propagation analysis have been the tools of choice in understanding the mechanisms that cause transonic buffet. Here we present a perspective on transonic buffet\, using results from correlation analysis\, streamwise and spanwise pressure distributions\, and the temporal evolution of skin friction lines on the surface of the Benchmark Supercritical Wing (BSCW). Skin friction lines and critical point theory are well established to describe 3D separated flows over solid walls and bodies. Together with correlation analysis of time-resolved fluid dynamics\, the evolution of skin friction lines reveals a new perspective on the driving mechanism for shock oscillations. This viewpoint supports\, in some ways\, earlier observations on the drivers of shock-induced separation in a finite span and infinite span wing but also reveals new insights on 3D shock oscillations. The presence and distribution of these critical points—unstable foci\, saddle points\, and nodes—lead to the formation of buffet cells or pockets of streamwise shock oscillations along the span. The topology of skin friction lines in the presence of these critical points gives rise to separation and re-attachment lines. In particular\, the propagation of buffet cells is shown to be due to the self-induced motion of contra-rotating unstable foci in the skin friction lines. The self-induced motion of these unstable foci\, or vortices\, causes them to convect inboard or oscillate spanwise. This perspective on transonic buffet based on the distribution of critical points of the skin friction lines\, enables possibilities of buffet control using low-order nonlinear dynamical system models. \nSpeaker: Magan Singh \nResearch Supervisor: Prof Kartik Venkatraman
URL:https://aero.iisc.ac.in/event/ph-d-engg-on-the-nature-of-transonic-buffet-in-a-finite-span-wing/
LOCATION:Online
CATEGORIES:Thesis Colloquium / Defence
ATTACH;FMTTYPE=image/jpeg:https://aero.iisc.ac.in/wp-content/uploads/2024/11/magan.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20241129T150000
DTEND;TZID=Asia/Kolkata:20241129T170000
DTSTAMP:20260404T181926
CREATED:20241126T093642Z
LAST-MODIFIED:20241126T093642Z
UID:10000031-1732892400-1732899600@aero.iisc.ac.in
SUMMARY:MTech(Res): Adjoint-Based Aerodynamic Shape and Mesh Optimization with High-order Discontinuous Galerkin Methods
DESCRIPTION:The aerodynamic shape of an aircraft plays a critical role in its performance. Aerodynamic Shape Optimization (ASO) modifies the shape to achieve desired performance metrics\, such as reduced drag or increased lift. ASO integrates numerical optimization techniques with Computational Fluid Dynamics (CFD). Gradient-based optimization techniques are widely employed for ASO. The adjoint solution enables the accurate and efficient computation of the gradients of the performance metrics with respect to the shape parameters. Performance metrics are derived from CFD solutions\, which inherently contain inaccuracies. These inaccuracies can affect the reliability of the optimization process. High-order methods\, like Discontinuous Galerkin (DG)\, offer improved accuracy for a computational cost comparable to Finite Volume methods in compressible flows\, making them well-suited for ASO. Adaptive mesh refinement can further improve the accuracy of simulations. The adjoint solution used for computing gradients also finds application in mesh adaptation. Combining adjoint-based mesh adaptation with gradient-based ASO provides better control over the inaccuracies during optimization.\n\nTowards this\, the present work performs ASO using high-order DG methods and devises strategies for incorporating adaptive mesh refinement. The shape is defined using smooth splines\, and the Free Form Deformation (FFD) method controls shape changes. With changes in the geometry\, the mesh needs to move to be consistent with the modified shape. A mesh deformation strategy ensures that the mesh evolves smoothly with geometry. A gradient-based method employing the Sequential Quadratic Programming (SQP) algorithm is used for optimization. The adjoint solution computes the gradients and passes them to the optimization algorithm. Optimization for a set of drag minimization problems\, including benchmark Aerodynamic Design Optimization Discussion Group (ADODG) test case 1 and inverse design problems\, is performed on non-adapted meshes.\n\nFurthermore\, a strategy is formulated to incorporate adjoint-based mesh adaptation within the optimization process. Based on the value of adjoint-based error estimates\, the strategy decides on instances of the optimization process that require control of the errors and\, thus\, mesh adaptation. Such a strategy leads to automated control of errors in the performance metrics\, thus improving the reliability and efficiency of the optimization process.\n\n\nSpeaker: Pandya Kush Tusharbhai\n\nResearch Supervisor: Aravind Balan
URL:https://aero.iisc.ac.in/event/mtechres-adjoint-based-aerodynamic-shape-and-mesh-optimization-with-high-order-discontinuous-galerkin-methods/
LOCATION:STC Seminar Hall\, Dept. of Aerospace Engineering
CATEGORIES:Thesis Colloquium / Defence
ATTACH;FMTTYPE=image/jpeg:https://aero.iisc.ac.in/wp-content/uploads/2024/11/pandya.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20241202T103000
DTEND;TZID=Asia/Kolkata:20241202T130000
DTSTAMP:20260404T181926
CREATED:20241128T095209Z
LAST-MODIFIED:20241202T054246Z
UID:10000036-1733135400-1733144400@aero.iisc.ac.in
SUMMARY:Ph.D. (Engg): Experimental Study of Isolator Shock Trains in Confined Co-Flowing Supersonic Streams
DESCRIPTION:Futuristic high Mach number flight systems using advanced air-breathing propulsion technologies typically have multiple flow paths with supersonic flows that merge before exiting the vehicle. The supersonic-supersonic co-flow configuration is a canonical model used to study the fundamental aerodynamics of these interactions. A pseudo-shock is a composite gas-dynamic feature produced in viscous-dominated internal flows due to shock-boundary layer interaction. It consists of a series of shocks (shock train) and a mixing region. The terms pseudo-shock and shock train are often used interchangeably. The isolator is a finite-length\, constant-area duct that contains the shock train across a wide range of operating conditions. Understanding and predicting the length\, adverse pressure handling capacity\, and instability of the shock train in the isolator is crucial for designing weight-critical aerospace systems. Most research on shock trains in isolators involves configurations without a co-flowing supersonic stream\, where the adverse pressure ratio is imposed mechanically. Fluidic throttling\, however\, establishes the isolator shock train in a supersonic-supersonic co-flow configuration\, which differs fundamentally from mechanical throttling\, which necessitates separate investigations. The limited literature on shock trains in supersonic-supersonic co-flow configurations shows the shock train in a narrow operating regime\, either in the overexpanded regime or with combustion in the mixed stream producing back pressure. These studies\, conducted in opaque tubular ducts\, relied on pressure measurements to infer shock train characteristics. Empirical relations of the shock train pressure distribution and length were not in consensus. This thesis aims to understand the shock train in a supersonic-supersonic co-flow configuration using an optically accessible test section that provides simultaneous time-resolved schlieren imaging and static pressure measurement. A wide range of operating conditions is achieved by converting an existing blowdown supersonic jet facility to a pressure-vacuum-driven system. A new modular supersonic-supersonic co-flow test section is established with independent control over Mach number\, isolator length\, and stagnation conditions of the separate streams\, offering a larger parameter space than previous studies. The flow topology and morphology of 158 shock train cases are studied experimentally\, leading to several key insights. Novel image analysis techniques and static pressure profile analysis enabled the extraction of the last shock in the shock train\, correctly identifying the number of shocks and separating the mixing region. The maximum number of shocks for the supersonic-supersonic co-flow configuration ranges from 6 to 8\, and the maximum length of the shock train in the pseudo-shock occupies an average of 6 to 6.5 times the isolator duct height. A major outcome is the revelation of a secondary shock at the isolator duct exit due to local entrainment effects of the supersonic co-flow. This secondary shock can significantly contribute to about 20% to 25% of the overall adverse pressure ratio of the isolator. Consequently\, the addition of the secondary shock increases the overall adverse pressure-handling capacity of the isolator to 85% to 90% of the normal shock pressure ratio corresponding to the isolator entrance Mach number. Four transition points are identified based on significant changes in shock train topology. Across various operating conditions and geometries\, the normalized adverse pressure ratio (normalized with respect to the normal shock pressure ratio for the isolator entrance Mach number) ranges between 0.4 and 0.85. The flow topology in cases where the core flow is overexpanded is notably different due to the absence of the secondary shock in the shock train and the core flow’s contribution to the overall adverse pressure ratio. A comparative study between fluidic and mechanical throttling is conducted by implementing a mechanical flap module in the same setup. In the mechanically throttled case\, the shock train system has a lower adverse pressure ratio than the fluidically throttled case and a higher number of shocks\, with a maximum of about 10 to 11. The large dataset produced in this study allows a critical evaluation of well-known empirical correlations for shock trains\, leading to a new prediction algorithm to address gaps in their predictive ability. A regression-based correlation is developed to estimate the imposed adverse pressure ratio for the given Mach number and stagnation pressure combinations of both flows. An adaptive pressure increase factor for estimating the shock train leading edge is obtained using a linear regression model for cases with available wall static pressure data. The ratio of the imposed adverse pressure ratio to the incipient pressure ratio for a turbulent boundary layer is used to estimate the initiation of large amplitude oscillations of the shock train leading edge\, with an average factor of 2. Spectral analysis of the STLE oscillations using wall static pressure fluctuations and data-driven analysis of schlieren image datasets showed a broad-band spectrum without distinguishable tones\, with a spread of less than 200 Hz. \n  \nSpeaker: A Balaji Himakar \nResearch Supervisor: Srisha Rao M V
URL:https://aero.iisc.ac.in/event/ph-d-engg-experimental-study-of-isolator-shock-trains-in-confined-co-flowing-supersonic-streams/
LOCATION:STC Seminar Hall\, Dept. of Aerospace Engineering
CATEGORIES:Thesis Colloquium / Defence
ATTACH;FMTTYPE=image/jpeg:https://aero.iisc.ac.in/wp-content/uploads/2024/11/Balaji-.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20241203T110000
DTEND;TZID=Asia/Kolkata:20241203T130000
DTSTAMP:20260404T181926
CREATED:20241126T095210Z
LAST-MODIFIED:20241129T054751Z
UID:10000033-1733223600-1733230800@aero.iisc.ac.in
SUMMARY:Ph.D. (Engg): Aeroacoustic sources in twin turbulent jets
DESCRIPTION:An understanding of the aeroacoustics of twin turbulent jets is essential for applications involving noise reduction in dual engine aircrafts and launch vehicles. The aeroacoustic dynamics of these jets are influenced by the spacing between the shear layer of the two jets as well as the spatio-temporal nature of the structures arising from the interaction between the two jets. In the present work\, we construct reduced-order models of aeroacoustic sources for single and twin subsonic jets ($M_j=0.9$\, $Re=3600$)\, with the individual jets being replicas of a single jet\, with the goal of accurately recovering the far-field sound over a rather wide band of frequencies St=[0.07\,1.0] and directivity angles\, phi = [30 deg\,120 deg] within a subdecibel level accuracy. These models are designed as linear combinations of spatio-temporally coherent SPOD modes obtained in terms of the Lighthill’s stress tensor\, which in turn is computed through large-eddy simulations (LES) of the turbulent jets.  The present investigation involves two sets of twin subsonic jets of diameter D each\, with spacings of 0.1D and 1D\, where the jets merge upstream and downstream of breakdown\, respectively.  This is observed to alter the dynamics of twin jet evolution.  The closely spaced twin jet decays the slowest due to reduced turbulent stresses which are\, however\, more broadband due to early merging.  Such jets also show strong shielding in the plane of jets\, especially at shallow directivity angles where sound levels may drop below that of the single jet.  The farther spaced twin jets have dynamics that are more akin to the constituent single jet with turbulent fluctuations peaking here at St=0.34\, but showing very little shielding\, with their OASPL mostly linked to the nature of extra flow structures created during merging.  Three-dimensional\, energy-ranked\, coherent structures (SPOD modes) for twin jets exhibit rather poor low-rank behaviour\, especially\, at the far-field spectral peak St=0.14\, unlike that of the single jet\, which is indicative of spatio-temporally complicated structures arising from the merging of the turbulent merging of the twin jets.  At St > 0.3\, the SPOD wavepackets show strong visual coherence\, resembling Kelvin–Helmholtz instability modes upstream of breakdown\, while at the lower frequencies there is very little spatial coherence with wavepackets peaking downstream of breakdown.  Although the leading SPOD modes radiate poorly\, reduced-order models using a subset of them\, up to 45 SPOD modes per frequency\, show for the first time remarkable match (within 1 dB) against the LES-predicted sound over 0.1 < St < 0.5\, at all angles investigated\, including that for the peak sound. At other frequencies\, the error barely exceeds a decibel\, except for the closely spaced twin jet which due to its greater hierarchy of spatio-temporal structures\, show slower convergence at the shallower angles for St > 0.5. \n  \nSpeaker:  Nishanth Muthichur \nResearch Supervisor: Santosh Hemchandra
URL:https://aero.iisc.ac.in/event/ph-d-engg-aeroacoustic-sources-in-twin-turbulent-jets/
LOCATION:Online
CATEGORIES:Thesis Colloquium / Defence
ATTACH;FMTTYPE=image/jpeg:https://aero.iisc.ac.in/wp-content/uploads/2024/11/nishant.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20241205T103000
DTEND;TZID=Asia/Kolkata:20241205T123000
DTSTAMP:20260404T181926
CREATED:20241129T112328Z
LAST-MODIFIED:20241129T112328Z
UID:10000037-1733394600-1733401800@aero.iisc.ac.in
SUMMARY:Ph.D. (Engg): Development of Scalable UAV Swarm-based Cooperative Search and Mitigation Approaches for Wildfire Management
DESCRIPTION:Climate change has significantly exacerbated the wildfire seasons\, increasing their frequency\, duration\, and scale of destruction. Globally\, wildfires destroy approximately 400 million hectares of land annually\, resulting in significant biodiversity loss\, degradation of soil nutrients\, and other ecological consequences. The fire locations are often inaccessible for ground-based interventions due to the challenging terrain\, and current human-centered firefighting strategies are both dangerous and unreliable\, primarily due to limited situational awareness of evolving wildfire scenarios. Additionally\, wildfire scenarios frequently involve rapidly spreading clusters of fires that surpass available resources. The wildfire scenarios also have large fires that require simultaneous action from multiple resources for mitigation. Unmanned Aerial Vehicles (UAVs) have emerged as an effective solution for enhancing situational awareness and facilitating interventions during wildfires. This thesis develops UAV swarm-based strategies for wildfire detection\, monitoring\, and mitigation in resource-constrained and dynamic environments.\nThe thesis first focuses on the early mitigation of clustered fires by assigning and scheduling firefighting UAVs under resource limitations. The objective is to reduce biodiversity loss through early mitigation of fires as Single UAV Tasks (SUTs) before they escalate into complex multi-UAV coordination tasks. The problem is reformulated as a shortest-schedule-route optimization and solved using two centralized approaches: Genetic Algorithm-based Routing and Scheduling with Time Constraints (GARST) and Hybrid Particle Swarm Optimization-based Routing and Scheduling with Time Constraints (HPSO-RST). GARST and HPSO-RST evaluated on homogeneous and heterogeneous UAV teams under full observability conditions show that HPSO-RST outperforms GARST\, with a higher success rate\, reduced mean fitness values\, and minimized burned areas. However\, the centralized nature of GARST and HPSO-RST limits scalability and convergence in dynamic environments with continuously evolving task demands. These challenges are further compounded in real-world firefighting scenarios by partial observability\, limited UAV sensor capabilities\, and physical constraints of UAVs related to payload and endurance. \nNext\, the complexities of non-stationary wildfire scenarios\, including growing fires\, emerging new fires\, partial observability\, and heterogeneous temporal and physical constraints\, are addressed in the SUT mitigation. The problem is reformulated into a sequential spatiotemporal task assignment framework with non-stationary cost functions under partial observability. The Conflict-aware Resource-Efficient Decentralized Sequential planner (CREDS) is developed to address the challenges for early wildfire suppression using heterogeneous UAV teams. CREDS employs a three-phase approach: fire detection using a search algorithm\, local trajectory generation with an auction-based Resource-Efficient Decentralized Sequential planner (REDS) incorporating a novel Deadline-Prioritized Mitigation Cost (DPMC) function\, and a conflict-aware consensus algorithm to establish global trajectories for mitigation. CREDS achieves high success rates under various conditions\, handling diverse fire-to-UAV ratios with scalability and robustness. The CREDS is robust against physical constraints\, managing resource limitations through increased UAV capacity\, additional UAVs\, and efficient refueling strategies. In resource-constrained wildfire scenarios\, the evolving nature of the wildfire may result in multiple spatially distributed larger fires\, which require simultaneous and coordinated mitigation efforts from multiple UAVs. The single swarm mission with a decentralized approach has less likelihood of multiple UAVs detecting the same target. The multi-swarm missions with distributed solutions lead to the collective action of swarm members in the search and mitigation of larger fires in large unknown areas. \nFinally\, the thesis develops the Multi-Swarm Cooperative Information-Driven Search and Divide-and-Conquer Mitigation Control (MSCIDC) approach for large-scale wildfire scenarios. This methodology employs cooperative UAV swarms to enhance fire detection and mitigation efficiency. A two-stage search process combines exploration and exploitation\, guided by thermal sensor data\, for rapid identification of fire locations. Dynamic swarm behaviors\, including regulative repulsion and merging\, minimize detection and mitigation times\, while local attraction accelerates the response of non-detector UAVs. The divide-and-conquer strategy ensures effective\, non-overlapping sector allocation for fire mitigation. The simulations for a pine forest environment show that MSCIDC reduces the average burned area and mission time considerably compared to existing multi-UAV methods\, providing faster and more efficient wildfire management. \nOverall\, the thesis presents scalable UAV swarm-based solutions to address clustered and large-scale wildfire management challenges. The UAV swarm-based solutions integrate decentralized spatiotemporal task assignment and multi-swarm strategies to effectively minimize ecological damage and provide robust solutions for real-world disaster management applications. \nSpeaker: Josy John \nResearch Supervisor: Dr. Suresh Sundaram
URL:https://aero.iisc.ac.in/event/ph-d-engg-development-of-scalable-uav-swarm-based-cooperative-search-and-mitigation-approaches-for-wildfire-management/
LOCATION:STC Seminar Hall\, Dept. of Aerospace Engineering
CATEGORIES:Thesis Colloquium / Defence
ATTACH;FMTTYPE=image/jpeg:https://aero.iisc.ac.in/wp-content/uploads/2024/11/john.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20241205T110000
DTEND;TZID=Asia/Kolkata:20241205T130000
DTSTAMP:20260404T181926
CREATED:20241204T104533Z
LAST-MODIFIED:20241204T104533Z
UID:10000040-1733396400-1733403600@aero.iisc.ac.in
SUMMARY:Ph.D. (Engg): Control of Alternating Flow Phenomena in Transonic Shock Wave Boundary Layer Interactions Over Payload Region of a Generic Launch Vehicle Model
DESCRIPTION:The transonic Mach number regime is a critical phase in the atmospheric ascent of launch vehicles\, where aerodynamic loads peak due to the combined effects of high freestream dynamic pressure and angle of attack. Besides high steady loads\, launch vehicles experience very high levels of pressure fluctuations caused by interactions between the unsteady λ-shock system and the boundary layer – a phenomenon known as Shock Wave Boundary Layer Interaction (SWBLI). These interactions can induce buffet excitation over the payload region\, leading to structural failure as well as control issues. NASA recommends limiting the nose cone semi-angle to 15° to mitigate shock oscillations\, labelling such designs as “Buffet-Proof.” However\, practical constraints such as payload mass & volume\, rocket diameter\, launch-pad limitations\, etc. necessitate the use of larger nose cone angles which are buffet-prone. While SWBLI has been well understood for two-dimensional flows\, data for three-dimensional launch vehicle type configurations is sparse in the literature\, with regard to even the basic understanding of the phenomena. Hence\, there is a need to develop physics-based models to handle SWBLI in practical cases. \nWind tunnel experiments were conducted to evaluate the aerodynamic impact of increasing nose cone angles to 20° and 25° in the transonic Mach number range. These investigations revealed critical flow characteristics such as abrupt jumps in pitching moments at small angles of attack (±4°)\, very high levels of pressure fluctuations\, λ-shock system oscillations\, and the occurrence of destabilizing counter-rotating vortices\, intermittent supersonic and subsonic flows (termed alternating flow phenomena) at specific Mach numbers of 0.90 and 0.94. The present research explores two approaches towards controlling SWBLI. The first involves a passive device\, a front-mounted Aerodisc\, systematically evaluated for the effect of geometric parameters at critical Mach numbers of 0.9 and 0.94 in the range of angles of attack of ±4°. The optimized Aerodisc configuration achieved the maximum noise reduction of 22 dB (Overall Sound Pressure Level\, OASPL). The second approach involves an active flow control technique using a pneumatic counter-flow jet. The jet parameters were varied during the tests. Jets with exit diameters of 3 mm and 4 mm operating at a pressure ratio of 3.2 achieved the greatest suppression by nearly 20 dB. Both the passive and active techniques demonstrated that by energizing the boundary layer\, the oscillating shock waves were stabilized\, the counter-rotating vortices removed and the upstream travelling Kutta-Waves associated with the alternating flows completely suppressed. \nThis research clearly brings out the basic physics of SWBLI and its control for 3-dimensional launch vehicle type configurations at transonic Mach numbers\, highlighting that the energizing the boundary layer is the key to control the transonic flow over launch vehicles with large blunt nose-cones. Based on the understanding of the physics of the phenomena and control accomplished in the present research\, it is possible to design and develop digital-twin based systems for efficient control of the phenomena and thereby improve the payload capability of heavy lift launch vehicles. \n  \nSpeaker: Dheerendra Bahadur Singh \nResearch Supervisor: Gopalan jagadeesh
URL:https://aero.iisc.ac.in/event/ph-d-engg-control-of-alternating-flow-phenomena-in-transonic-shock-wave-boundary-layer-interactions-over-payload-region-of-a-generic-launch-vehicle-model/
LOCATION:Centre of Excellence in Hypersonics conference hall\, Room No.AE-239\,
CATEGORIES:Thesis Colloquium / Defence
ATTACH;FMTTYPE=image/jpeg:https://aero.iisc.ac.in/wp-content/uploads/2024/12/Dheerendra-.jpg
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BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20241206T140000
DTEND;TZID=Asia/Kolkata:20241206T170000
DTSTAMP:20260404T181926
CREATED:20241204T101223Z
LAST-MODIFIED:20241204T101223Z
UID:10000039-1733493600-1733504400@aero.iisc.ac.in
SUMMARY:Ph.D. (Engg): Multiscale modelling and design of multifunctional composites for microwave absorption applications
DESCRIPTION:Microwave absorption materials (MAMs) are crucial for both long-standing aeronautical and emerging space security applications\, with carbon-based materials traditionally dominating the field due to their exceptional strength and lightweight nature. In recent years\, other ceramic-based materials have emerged as promising alternatives\, due to their superior resistance to thermal detection\, due in turn to their low thermal conductivity and inertness to oxidation at high temperatures. However\, such ceramics by themselves often lack the mechanical flexibility and lightweight characteristics essential for aircraft. Combining such ceramics with carbon-based materials renders the achievement of an optimal balance of electromagnetic and mechanical (specific strength\, stiffness\, stability) performances\, possible. Traditional experimental approaches to designing MAMs are resource-intensive\, given the multidimensional parametric space that must be explored. This research adopts a multiscale computational framework\, leveraging minimal self-generated experimental data to efficiently design ceramic-carbon hybrid materials for broadband microwave absorption\, ensuring durability and low observability in extreme environments.\nThe initial phase investigates the microwave absorption capabilities of ceramic-based auxetic metamaterials with four distinct topologies: star\, re-entrant\, anti-tetrachiral\, and cross-chiral. These structures were chosen to analyse their reflection loss (RL) performance under transverse electric (TE) and transverse magnetic (TM) polarised electromagnetic (EM) waves. An in-house computationally-efficient homogenisation tool\, based on the Variational Asymptotic Method (VAM)\, was employed to derive the effective EM properties. These properties were then used to compute RL spectra by evaluating the scattering matrices. Interestingly\, the star and cross-chiral auxetic structures demonstrated identical absorption capabilities despite their architectural differences\, achieving a maximum absorption of 99.99% (RL of -40 dB) with a thickness of 3.5 mm under TM-polarised EM waves. These absorbers maintained RL < -10 dB for incidence angles up to 700. However\, TE-polarised EM waves led to more reflection (RL > -6 dB)\, highlighting a significant performance gap.\nLater\, to overcome the limitations observed with auxetic metamaterials\, a novel sandwich composite structure was proposed to achieve broadband RL under both TE and TM polarisations. This sandwich panel integrates ceramic-coated graphite fibre-reinforced polymer (C-GFRP) composite as the face sheet with a ceramic-based star auxetic metamaterial as the core. Representative volume elements (RVEs) of C-GFRP composites are generated using the in-house tool\, and the effective properties of the unidirectional C-GFRP face sheets were computed using the in-house homogenisation tool and validated with experimental results from the literature. A detailed parametric study of 300 analyses was conducted using the in-house transfer matrix method (TMM) tool to identify the optimal designs. Two configurations thus identified from the analysis are (a) Vf = 15% (uncoated) and (b) Vf = 20% with a ceramic coating volume fraction (Cf) of 70%. Configuration (a) achieved RL < -10 dB up to an incidence angle of 400\, while configuration (b) extended this performance up to 600. Both configurations attained broadband RL performance\, covering the entire X-band frequency range.\nThe final phase of the study experimentally validates the multiscale computational framework. For this purpose\, multiphase nanocomposites comprising carbon-based nanoparticles (MWCNTs) and other ceramic inclusions (BaTiO₃\, CoFe₂O₄) are fabricated and tested for broadband RL capabilities. Comprehensive characterisation techniques such as SEM\, TGA\, and X-ray computed tomography were employed to confirm nanoparticle morphology\, volume fractions\, and distribution. Reflection and transmission measurements using a two-port vector network analyser (VNA) provided scattering parameters within the X-band. Effective EM properties were derived using the Nicolson-Ross-Weir (NRW) algorithm. At the same time\, an in-house optimisation tool\, based on Nelder-Mead and L-BFGS-B methods\, was employed to extract the individual inclusion properties. Parametric studies revealed that composites with high BaTiO₃ or MWCNTs content exhibited surface impedance mismatches\, leading to EM wave reflection rather than absorption. In contrast\, CoFe₂O₄ dominant composites demonstrated superior broadband RL (< -10 dB) for different thickness samples\, attributed to improved surface impedance matching. Additionally\, the influence of incident angle and polarisation was assessed. TM-polarised EM waves provided broadband RL for incidence angles up to 800\, while TE-polarised EM waves were effective only up to 400 due to distinct field interaction mechanisms. The study demonstrates a versatile framework for designing novel nanocomposites tailored to broadband or frequency-selective microwave absorption applications\, addressing the limitations of traditional approaches.\n\nSpeaker: Attada Phanendra Kumar\nResearch Supervisor: Prof. Dineshkumar Harursampath
URL:https://aero.iisc.ac.in/event/ph-d-engg-multiscale-modelling-and-design-of-multifunctional-composites-for-microwave-absorption-applications/
LOCATION:STC Seminar Hall\, Dept. of Aerospace Engineering
CATEGORIES:Thesis Colloquium / Defence
ATTACH;FMTTYPE=image/jpeg:https://aero.iisc.ac.in/wp-content/uploads/2024/12/Attada-.jpg
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BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20241209T103000
DTEND;TZID=Asia/Kolkata:20241209T123000
DTSTAMP:20260404T181926
CREATED:20241202T071527Z
LAST-MODIFIED:20241202T071527Z
UID:10000038-1733740200-1733747400@aero.iisc.ac.in
SUMMARY:Ph.D. (Engg): "Design and Development of Novel Quadcopters for Reliable Operations in Cluttered Environments"
DESCRIPTION:The quadcopters are increasingly used in cluttered environments as rapid advancements are made in the development of lightweight sensors and payloads. Intelligence Surveillance Reconnaissance (ISR) missions\,  crack detection on the interior surface of a pipe/tunnel\, and close inspection in tropical forest environments are a handful of examples where quadcopters are being deployed. Safe operation in these cluttered environments is challenging mainly due to the proximity of obstacles to the spinning propellers. The complete loss of the propeller makes it impossible to have full-attitude stability on traditional quadcopters. After the propeller failure\, the existing literature relies upon reduced-attitude control\, where the control authority about yaw is sacrificed. To maintain reduced attitude control\, the quadcopter must continuously spin rapidly about the yaw axis. Such a maneuver is risky\, and the quadcopter may not continue the mission after the actuator fails completely. \nFor reliable operation in a cluttered environment\, the quadcopter should also be able to reduce its span mid-flight to minimize the risk of the propeller collision with the obstacles. The quadcopter should remain fully controllable for all spans to enhance usability and applicability. The degree of span reduction should be controllable between the nominal and extreme states. Ideally\, the quadcopter should also be tolerant to the complete failure of the additional “span-reducing” actuator (not to be confused with primary rotor-based actuators). For the broader range of applications\, the concept or the mechanism of span-reducing should be weight-scalable.  The effective execution of an indoor cluttered environment mission may also require a mid-flight flipping quadcopter for gaining the perception of the environment along both nadir and zenith directions with respect to the payload.  Traditional quadcopters cannot sustain the inverted flight and thus lack the maneuverability and reliability to operate safely and effectively in a cluttered environment. Enhancements to the fundamental principles governing quadcopter dynamics are required to facilitate challenging operations in cluttered environments. \nThe first half of the presentation consists of the design and development of a morphing quadcopter called Scissorbot. Scissorbot is a novel mid-flight reconfigurable geometry quadcopter that reduces its lateral span using a single servo-motor coupled with a compact bevel differential gearbox. Scissorbot possesses unique practical features\, including weight-scalability\, geometrical symmetricity\, and fault tolerance to the servo-motor. Scissorbot achieves significant lateral-span reduction without the risk of propeller tip collision by positioning adjacent propellers in different planes. The maximum lateral-span reduction is 88% of its nominal value (highest reported in the literature). This work derives a detailed attitude dynamics model and analyzes the gearbox theoretically. Attitude control is accomplished by implementing a Sliding Mode Controller (SMC) that exhibits robustness to parametric uncertainties such as the moment of inertia and aerodynamic disturbances due to the overlapping of the propellers. The control allocation loop is parametrized with respect to the morphing angle to adapt to the reconfiguration process.  The performance of the Scissorbot is validated using simulations\, test-benches as well as real-world free-flight experiments. \nThe other half presents the design and development of a novel Variable-Pitch-Propeller (VPP) quadcopter called Heliquad. The cambered airfoil propeller-equipped Heliquad generates significantly more torque than its symmetrical airfoil counterpart\, ensuring full-attitude hover equilibrium on only three of its working actuators. VPPs can generate reverse thrust\, enabling mid-flight flip and sustained inverted flight on Heliquad. A unified control architecture ensures the tractability of the Heliquad. Furthermore\, a Neural-Network (NN) based control allocation method is proposed to address the non-linearities in the actuator dynamics. The control allocation is reconfigurable based on the index of the faulty actuator. For the experimental validation\, a prototype of  Heliquad is built. The design and analysis of the VPP mechanism installed on the Heliquad prototype are also presented. The performance of Heliquad is validated using simulations\, test-benches\, and real-world free-flight experiments. The safe recovery of a quadcopter architecture (Heliquad) with full attitude control after the complete failure of an actuator is demonstrated for the first time in the literature. \nSpeaker:  Kulkarni Eeshan Prashant \nResearch Supervisor: Prof Suresh Sundaram
URL:https://aero.iisc.ac.in/event/ph-d-engg-design-and-development-of-novel-quadcopters-for-reliable-operations-in-cluttered-environments/
LOCATION:STC Seminar Hall\, Dept. of Aerospace Engineering
CATEGORIES:Thesis Colloquium / Defence
ATTACH;FMTTYPE=image/jpeg:https://aero.iisc.ac.in/wp-content/uploads/2024/12/Eeshan.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20241209T110000
DTEND;TZID=Asia/Kolkata:20241209T130000
DTSTAMP:20260404T181926
CREATED:20241209T043233Z
LAST-MODIFIED:20241209T052550Z
UID:10000042-1733742000-1733749200@aero.iisc.ac.in
SUMMARY:Boundary Layer Transition Experiment in a Supersonic Flight
DESCRIPTION:In fluid mechanics\, the boundary-layer transition is a very important phenomenon for high-speed flows because it severely affects the skin friction and heating rates on the model surface. The classical correlations for high-speed flows have been developed based on experimental observations in wind tunnels. When the experiments are performed\, they are mostly controlled by the flow Reynolds number because the maximum size of the model is fixed based on the size of the test section of a wind tunnel. In most cases\, artificial surface roughness is introduced to initiate a transition towards turbulence because of the restricted model size. The flow Reynolds number and Station number on the model surface are crucial non-dimensional indicative parameters that characterize the transition behaviour of the flow. A realistic approach to simulate the effect of model size for studying the boundary layer transition is to conduct a flight test. Against this backdrop\, a systematic procedure is adopted to design a generic ogive nose cone-cylinder payload module (0.7 m long) for a boundary-layer transition experiment in a supersonic flight. Nickel thin film gauges are used to infer heat transfer data on the payload module at various locations for 10s flight duration. The heat transfer data from the temperature history are obtained using two different techniques: one-dimensional semi-infinite heat conduction analysis and deconvolution method. The analysis from flight data indicates a peak Mach number of 2.018\, which is achieved after 1.157s of flight. The Reynolds number during the flight is of the order of 10 million \, which is an indication of completely turbulent flow during flight duration. It is also supported by heat transfer prediction through the Stanton number\, which falls in the range of 0.5 to 1.2. It is concluded that the length of the model is not sufficient to initiate a transition towards relaminarization because the Stanton number and Reynolds number variation do not show any drastic change at any of the gauge locations. However\, the promising surface temperature histories from nickel thin film gauges during flight are very useful to devise more realistic heat-transfer models for for higher time scales flow duration through inverse heat-conduction analysis and modern machine learning models.\n\n Speaker: Prof. Niranjan Sahoo\n\nBiography : \nProf. Sahoo’s research interests lie in high-speed aerodynamics\, ground test facilities\, measurements for forces and heat transfer\, shock waves\, and their applications in allied fields\, combustion\, energy \, hydrogen energy and storage. He has been awarded fellowships from DAAD Germany\, BOYCAST and Young Scientist Scheme from DSTHe has offered several online courses (Applied Thermodynamics\, Power Plant System Engineering\, Advanced Thermodynamics and Combustion\, Fundamentals of Compressible Flow) on NPTEL platform. He has over 115 Journal Publications\, 153 in conference proceedings and 11 Book Chapters.
URL:https://aero.iisc.ac.in/event/boundary-layer-transition-experiment-in-a-supersonic-flight/
LOCATION:AE Auditorium
ATTACH;FMTTYPE=image/jpeg:https://aero.iisc.ac.in/wp-content/uploads/2024/12/Niranjan.jpg
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BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20241209T110000
DTEND;TZID=Asia/Kolkata:20241209T130000
DTSTAMP:20260404T181926
CREATED:20241209T045719Z
LAST-MODIFIED:20241209T051859Z
UID:10000043-1733742000-1733749200@aero.iisc.ac.in
SUMMARY:The Dual Mesh Control Domain Method: A Marriage of the Finite Element and Finite Volume Methods
DESCRIPTION:The finite element method (FEM) and finite volume method (FVM) are widely used numerical techniques for solving differential equations\, with FEM mainly applied in solid mechanics and FVM in heat transfer and fluid dynamics. Both methods have drawbacks: FEM can lead to discontinuities at element interfaces unless C1-continuous approximations are used\, while FVM relies on ad-hoc techniques from finite difference methods\, lacking explicit approximations and concepts of duality. In 2019\, Reddy introduced the dual mesh control domain method (DMCDM)\, combining features of both FEM and FVM. DMCDM uses a primal mesh for dependent variable interpolation and a dual mesh for integral satisfaction of governing equations\, enhancing the methods’ effectiveness. This lecture discusses DMCDM’s key features and demonstrates its applications in various linear and nonlinear problems. \nSpeaker: Prof J N Reddy \nBiography:  \nDr. Reddy is a Distinguished Professor and Regents’ Professor at Texas A&M University\, holding the O’Donnell Foundation Chair IV in Mechanical Engineering. An ISI highly cited researcher\, he has authored 25 textbooks and over 800 journal papers\, making significant contributions to applied mechanics\, particularly through his shear deformation theories\, including the Reddy third-order plate theory and Reddy layerwise theory. These theories have influenced commercial finite element software like ABAQUS and NISA. Recently\, his research has focused on locking-free shell finite elements and nonlocal continuum mechanics related to architected materials and structural failures. Dr. Reddy has received numerous prestigious awards\, including the 2023 Leonardo da Vinci Award\, the 2023 Michael Païdoussis Medal\, and the 2019 SP Timoshenko Medal\, among others. He is a member of eight national academies\, including the U.S. National\nAcademy of Engineering\, and a foreign fellow of several international engineering academies.
URL:https://aero.iisc.ac.in/event/the-dual-mesh-control-domain-method-a-marriage-of-the-finite-element-and-finite-volume-methods/
LOCATION:Auditorium\, Department of Physics\, IISc
ATTACH;FMTTYPE=image/jpeg:https://aero.iisc.ac.in/wp-content/uploads/2024/12/reddy1.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20241218T110000
DTEND;TZID=Asia/Kolkata:20241218T123000
DTSTAMP:20260404T181926
CREATED:20241217T044151Z
LAST-MODIFIED:20241217T044151Z
UID:10000044-1734519600-1734525000@aero.iisc.ac.in
SUMMARY:Phase Transformations in Multifunctional Materials
DESCRIPTION:Phase transformation materials are characterized by their ability to rapidly and reversibly switch between distinct properties\, such as insulating and conducting\, paramagnetic and ferromagnetic\, or Li-rich and Li-poor. These transformations\, however\, are accompanied by abrupt structural changes in the crystal lattices\, which can nucleate defects\, accumulate strain energy\, and accelerate material decay. We investigate these transformations in multifunctional materials from the viewpoint of Ericksen’s multiple energy wells. By doing so\, we identify important links between material constants\, crystallographic microstructures\, and macroscopic properties. This approach to understanding material behavior from the perspective of energy landscapes may suggest new ways to design materials with improved properties and lifespans. In this talk\, I will present our findings on phase transformations in battery electrodes (intercalation compounds) and soft magnetic alloys.\n\n Speaker: Ananya Balakrishna\n\nBiography:\nAnanya Renuka Balakrishna is an Assistant Professor in the Materials Department at the University of California Santa Barbara. She received her B.Tech degree in Mechanical Engineering from the National Institute of Technology Karnataka and her Ph.D. in Solid Mechanics and Materials Engineering from the University of Oxford. Before her current appointment\, she was a Lindemann Postdoctoral Fellow at MIT and the University of Minnesota and joined the faculty in the Department of Aerospace & Mechanical Engineering at the University of Southern California in 2020. Her research group develops theoretical models to understand the interplay between fundamental material constants and microstructural instabilities\, and how they collectively shape the physical response of a material.
URL:https://aero.iisc.ac.in/event/phase-transformations-in-multifunctional-materials/
LOCATION:AE Auditorium
CATEGORIES:AE Seminar
ATTACH;FMTTYPE=image/jpeg:https://aero.iisc.ac.in/wp-content/uploads/2024/12/Ananya-.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20241219T090000
DTEND;TZID=Asia/Kolkata:20241220T173000
DTSTAMP:20260404T181926
CREATED:20241219T044539Z
LAST-MODIFIED:20241219T044539Z
UID:10000045-1734598800-1734715800@aero.iisc.ac.in
SUMMARY:Two-Day Short Course on Mathematics and Computing of Risk\, Reliability and Resilience in Network and Enterprise Systems
DESCRIPTION:This course is designed to familiarize the students with the mathematical concepts and computational techniques in quantifying the risk\, reliability and resilience (RRR) of large\, complex systems\, in the presence of multiple types of uncertainty. Often the information available for RRR analysis is heterogeneous\, coming from multiple sources (models\, tests\, experts) and in multiple formats. The use of Bayesian methods to integrate heterogeneous information will be presented. The use of RRR quantification results in various types of decisions will be discussed\, such as system design\, manufacturing\, operations\, and sustainment. The concept and use of digital twins that continuously update the system model with incoming data to maintain high levels of system performance and resilience will be presented. Application examples from engineering systems (e.g.\, aircraft\, buildings)\, business enterprise systems (e.g.\, manufacturing and distribution supply chains)\, and civil infrastructure systems (e.g.\, power grid\, transportation) will be used to illustrate the RRR techniques for large complex systems. For more information\, please visit our website https://abcmc.iisc.ac.in/events/ \n  \nSpeaker: Dr. Sankaran Mahadevan \n  \nBiograpgy:  \nProfessor Sankaran Mahadevan has thirty-six years of research and teaching experience in reliability and risk methods\, uncertainty quantification\, model validation\, system health and risk management\, and optimization under uncertainty. His research has been extensively funded by NSF\, NASA\, FAA\, DOE\, DOD\, DOT\, NIST\, General Motors\, Chrysler\, Union Pacific\, American Railroad Association\, and Sandia\, Idaho\, Los Alamos and Oak Ridge national laboratories. His research contributions are documented in more than 700 publications\, including two textbooks on reliability methods and 350 journal papers. He is one of the world’s highest cited researchers in the field of uncertainty and risk analysis (Google Scholar h-index 90). He has directed 56 Ph.D. dissertations and 24 M. S. theses and has taught many industry and university short courses on the mathematics and computing of uncertainty and reliability analysis. Professor Mahadevan is a Fellow of AIAA\, Fellow of the Engineering Mechanics Institute (ASCE)\, and Fellow of Prognostics and Health Management Society (PHM). He is the winner of several prestigious awards including the Senior Distinguished Research Award from the International Association of Structural Safety and Reliability\, NASA Next Generation Design Tools award\, SAE Distinguished Probabilistic Methods Educator Award\, and best paper awards in several international conferences. He recently completed his service as President of the ASCE Engineering Mechanics Institute and Managing Editor of ASCE-ASME Journal of Risk and Uncertainty (Part B: Mechanical Engineering). He is currently Chair of the ASME VVUQ50 Committee on Advanced Manufacturing.
URL:https://aero.iisc.ac.in/event/two-day-short-course-on-mathematics-and-computing-of-risk-reliability-and-resilience-in-network-and-enterprise-systems/
LOCATION:Auditorium (AE 005)\, Department of Aerospace Engineering
ATTACH;FMTTYPE=image/jpeg:https://aero.iisc.ac.in/wp-content/uploads/2024/12/TwoDay.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20241227T110000
DTEND;TZID=Asia/Kolkata:20241227T130000
DTSTAMP:20260404T181926
CREATED:20241224T090743Z
LAST-MODIFIED:20241224T090743Z
UID:10000046-1735297200-1735304400@aero.iisc.ac.in
SUMMARY:Ph.D. (Engg): Effect of Surface Roughness on Mechanical Strength of Adhesively Bonded CFRP Joints – Experimental and Numerical Studies
DESCRIPTION:This dissertation focuses on surface preparation and its effect on the shear strength of adhesively bonded Single Lap Joints (SLJs) in Carbon Fiber Reinforced Polymer (CFRP)\, their fracture properties\, and the associated Non-Destructive Evaluation (NDE) parameters. The surface preparation was carried out using different grades of emery paper so that the interfaces of different roughness were available for bonding. The morphology of the interfaces before bonding was captured with the light interferometry [Micro-System Analyzer (MSA)]. Then\, roughness parameters were characterized by contact-based measurements. The correlations of the contact angle between the droplet of liquid and the bonding interface with varied surface roughness and the increase in area with respect to the smoothest surface were established. CFRP\, one of the most preferred composite materials in the aerospace industry\, has been chosen in this study. \nA band of NDE techniques was utilized to evaluate the effects of surface roughness in ABJs of CFRP adherends. This included Ultrasonic Testing (UT)\, Infra-Red Thermography (IRT)\, Acoustic Wave Propagation (AWP)\, Acoustic Emission Testing (AET)\, X-ray Radiography Testing (XRT)\, and Digital Image Correlation (DIC). \nIn the FEA model it is difficult to model micro-roughness on the adherend of mesoscale. Hence\, an approach was presented to model the fracture in rough interfaces. Modelling of joints with varied roughness was considered\, and fracture properties were implemented in the commercial FEA software Abaqus. The surface-to-surface interactions were modelled for each interface. The interaction was based on the Cohesive Zone Model (CZM). Traction separation laws were derived from experimental fracture energies. \n  \nSpeaker: Laxmikant Mane Sarjerao \nResearch Supervisor: Prof Bhat M Ramachandra
URL:https://aero.iisc.ac.in/event/ph-d-engg-effect-of-surface-roughness-on-mechanical-strength-of-adhesively-bonded-cfrp-joints-experimental-and-numerical-studies/
LOCATION:STC Seminar Hall\, Dept. of Aerospace Engineering
CATEGORIES:Thesis Colloquium / Defence
ATTACH;FMTTYPE=image/jpeg:https://aero.iisc.ac.in/wp-content/uploads/2024/12/Laxmikant-.jpg
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BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20250110T150000
DTEND;TZID=Asia/Kolkata:20250110T170000
DTSTAMP:20260404T181926
CREATED:20241230T092927Z
LAST-MODIFIED:20241230T092927Z
UID:10000047-1736521200-1736528400@aero.iisc.ac.in
SUMMARY:PHONONIC MATERIALS – AN AVENUE FOR PASSIVE FLOW CONTROL
DESCRIPTION:Specific modal and non-modal mechanisms (flow coherences) in fluid flows\, associated with distinct time and length scales\, govern important flow phenomena\, e.g.\, laminar-to-turbulent transition\, turbulent drag\, and flow separation. Consequently\, numerous passive strategies featuring compliant materials have explored the effect of Fluid-structure interaction (FSI) on various flow coherences. In recent years\, the emergence of Phononic materials (PMs) with engineered internal architectures provides a powerful tool to encode desired material behavior. Therefore\, flow configurations leveraging fluid-PM interaction offer an exciting opportunity to precisely engineer the spatiotemporal scales of the structural response relative to the flow coherences\, allowing a more fundamental and systematic study of FSI physics. Initial research efforts adopting the fluid-PM framework have demonstrated effective interaction with flow instabilities\, e.g.\, Tollmien–Schlichting waves. Building on these efforts\, our research group explores interesting FSI dynamics of canonical fluid flow – PM configurations to illustrate the potential of PMs for passive flow control. \nIn this talk\, I will present an overview of the PM design strategy and numerical and experimental results from our current fluid-PM interaction research projects. We configure PMs as subsurfaces and explore their FSI with flow coherences in various flow settings\, e.g.\, flow coherences in a turbulent channel flow\, Karman vortex streets in a subsonic flow past a cylinder\, wake vortices in flow past an airfoil. \n  \nSpeaker: Dr. Vinod Ramakrishnan \n  \nBiography:  \nDr. Vinod Ramakrishnan is a Postdoctoral research associate working with Dr. Kathryn Matlack at the University of Illinois at Urbana-Champaign. His research involves numerical and experimental investigations of Fluid-Metamaterial interaction models to explore avenues for passive flow control. Vinod holds a PhD in Mechanical Engineering from the University of California San Diego (2023) and a B. Tech in Mechanical Engineering from IIT Gandhinagar (2018). He worked with Dr. Michael Frazier during his PhD\, where his research explored phase transitions and strategies to control domain walls in multistable metamaterials to promote their adoption in applications\, e.g.\, energy harvesting\, mechanical memory devices\, and deployable structures.
URL:https://aero.iisc.ac.in/event/phononic-materials-an-avenue-for-passive-flow-control/
LOCATION:AE Auditorium
CATEGORIES:AE Seminar
ATTACH;FMTTYPE=image/jpeg:https://aero.iisc.ac.in/wp-content/uploads/2024/12/Vinod-.jpg
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BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20250116T110000
DTEND;TZID=Asia/Kolkata:20250116T130000
DTSTAMP:20260404T181926
CREATED:20250115T054120Z
LAST-MODIFIED:20250115T054120Z
UID:10000048-1737025200-1737032400@aero.iisc.ac.in
SUMMARY:Ph.D. (Engg): Transonic shock buffet in an axial flow fan
DESCRIPTION:Transonic shock buffet\, a self-sustained shock oscillation resulting from shock-boundary layer interaction\, is observed across a range of operating points on the performance map of a transonic axial flow fan. Shock oscillations impart time-varying air loads on fan blades with the potential of leading to fatigue-induced structural failure. Accurate estimations of shock buffet onset\, shock displacement\, and buffet frequency are critical to lifing assessment of turbomachinery blades. This study focuses on predicting transonic shock buffet in a transonic axial flow fan using high-fidelity numerical simulations\, followed by investigation of its underlying mechanisms through wave propagation analysis and modal analysis of buffet flow. Steady flow solutions obtained using a RANS solver predict performance characteristics and capture key features of the fan’s shock structure in conformation with experimental and numerical results from the literature. Unsteady flow simulations on a full-annulus model using URANS successfully capture shock buffet and its salient attributes at two operating points—near design mass flow and near stall. Wave propagation analysis and spectral proper orthogonal decomposition of buffet flow reveal a feedback loop of upstream and downstream propagating pressure perturbation waves driving shock buffet. Subtle modification to Lee’s buffet model is proposed for accurately predicting buffet frequency in a turbomachinery context. Buffet flow is characterized by circumferential\, radial\, and stream-wise pressure perturbation waves\, with circumferential flow periodicity breaking down during buffet. A global stability analysis framework is presented and its prognostic potential for predicting shock buffet in turbomachinery is evaluated. The global stability analysis framework enables accurate prediction of buffet frequencies and associated modes with drastically reduced computational cost compared to that required for unsteady simulations. Finally\, the aeromechanical response of the fan to buffet-induced unsteady air loads is assessed. The buffet frequencies do not excite resonant blade vibrations or buffeting but induce an alternating mis-staggering structural response in the fan blades due to aerodynamic mistuning arising of buffet flow. In summary\, we have shown\, for the first time\, transonic shock buffet in an axial flow fan can be captured using a full-annulus simulation. Further\, this study advances the understanding of transonic shock buffet mechanisms\, demonstrating robust methodologies for predicting shock buffet\, and assessing its aeromechanical implications in turbomachinery. \n  \nSpeaker : Jyoti Ranjan Majhi \n  \nResearch Supervisor: Prof. Kartik Venkatraman.
URL:https://aero.iisc.ac.in/event/ph-d-engg-transonic-shock-buffet-in-an-axial-flow-fan/
LOCATION:Auditorium (AE 005)\, Department of Aerospace Engineering
CATEGORIES:Thesis Colloquium / Defence
ATTACH;FMTTYPE=image/jpeg:https://aero.iisc.ac.in/wp-content/uploads/2025/01/Jyoti-.jpg
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