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TZID:Asia/Kolkata
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TZOFFSETFROM:+0530
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DTSTART:20240101T000000
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BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20240205T140000
DTEND;TZID=Asia/Kolkata:20240205T150000
DTSTAMP:20260404T183424
CREATED:20240324T082740Z
LAST-MODIFIED:20240803T052011Z
UID:10000001-1707141600-1707145200@aero.iisc.ac.in
SUMMARY:Innovations in Aerospace Systems – Current Research (including Artificial Intelligence) and Future Challenges
DESCRIPTION:Aircraft and spacecraft are highly complex systems\, comprising various subsystems such as flight control\, propulsion\, and power. These subsystems feature Multiple Input & Multiple Output (MIMO) configurations and exhibit highly nonlinear characteristics. Over recent years\, there has been a growing demand for aerospace systems with improved performance\, fault tolerance\, and enhanced autonomous capabilities. This presentation explores how fault diagnosis\, prognosis and artificial intelligence can address these requirements. It delves into model-based\, data-driven (artificial intelligence)\, and hybrid approaches\, which have been proposed for fault diagnosis and prognosis. Furthermore\, the author has proposed novel methods to meet these evolving demands. These innovative techniques\, including the Covariance-based adaptive unscented Kalman filter (CAUKF)\, Binary grid covariance adaptive Kalman filter (GAUKF)\, Reinforced Unscented Kalman Filter (an integration of UKF and Reinforcement Learning techniques)\, and Growing Neural Networks (GNN)\, hold promise for aerospace system enhancement. The presentation will feature case studies illustrating the application of these methods in spacecraft attitude and orbit control systems\, as well as aircraft engines. By examining the latest advancements and methodologies\, attendees will gain insights into the pivotal role these techniques play in enhancing aerospace system reliability and efficiency\, ultimately addressing current research challenges and shaping the trajectory of future aerospace systems. \n  \nSpeaker: Prof. Krishna Dev Kumar \nBiography: Dr. Krishna D. Kumar is a Professor of Aerospace Engineering and Director of Artificial Intelligence for Aerospace Systems (AIAS) Laboratory at Toronto Metropolitan University\, Canada. Additionally\, he is the Founder and President of iSAC Systems Inc\,  a leader inArtificial Intelligence (AI)\, Internet-of-Things (IoT)\, and Smart Systems since 2010. Prof. Kumar has made outstanding contributions with major impact in the areas of spacecraft dynamics and control\, fault diagnosis and prognosis\, artificial intelligence\, and predictive analytics with over 250 publications including 5 books\, 14 intellectual properties\, and four patents. His AI and IoT products have been deployed across diverse industries\, including aerospace\, transportation\, and waste management. His illustrious career boasts several remarkable achievements\, including the development of AI-powered predictive analytics for the NASA Kepler Spacecraft and Aircraft Engines\, the world’s first 100-gram miniature satellite\, and the world’s first miniature IoT monitoring systems for Bombardier Trains\, and Safran Aircraft Landing gears.  Prof. Kumar’s exemplary contributions to the field have been widely recognized with numerous national and international awards\, including the prestigious Canada Research Chair Award\, Ontario Early Researcher Award\, Associate Fellow of American Aeronautics and Astronautics\, Japan Society for the Promotion of Science Fellow\, Japan Science and Technology Agency Fellow\, Member of the International Academy of Astronautics in France\, the Sarwan Sahota Ryerson Distinguished Scholar Award\, and the Eminent Alumnus Award from Veer Surendra Sai University of Technology\, Sambalpur\, India. Furthermore\, Prof. Kumar is the Co-Editor of Acta Astronautica and Transactions of the Japan Society for Aeronautical and Space Sciences.
URL:https://aero.iisc.ac.in/event/innovations-in-aerospace-systems-current-research-including-artificial-intelligence-and-future-challenges/
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:20240304T200000
DTEND;TZID=Asia/Kolkata:20240304T213000
DTSTAMP:20260404T183424
CREATED:20240324T084614Z
LAST-MODIFIED:20240802T165719Z
UID:10000002-1709582400-1709587800@aero.iisc.ac.in
SUMMARY:Nonequilibrium reacting flows: First principles based modeling for chemical kinetics and hydrodynamics
DESCRIPTION:Predicting state of the gas hitting vehicles flying at hypersonic speeds (Mach ~5) is challenging and is an exciting area of research. Hypersonic flows create shock waves\, which compress and heat the surrounding gas to high-temperatures\, nearly thousands of Kelvins. At these high temperatures\, air molecules (nitrogen and oxygen) dissociate into atomic species. Predicting the extent of dissociation and recombination of atomic species is important since the state of the gas near the vehicle surface determines heating rates and gas-surface chemistry that damages the heat shield. Since experiments in ground test facilities do not mimic such extreme flight conditions\, numerical simulation plays an important role. Predictive numerical simulations require accurate reaction chemistry models. Computational models developed thus far range from simple empirical models fit to limited experimental data to models with millions of input parameters that track individual quantized energy state transitions. The level of model fidelity required for accurate engineering analysis remains an open question of active research. Models coupling internal energy and dissociation chemistry tend to be developed at either the kinetic scale or the continuum scale. In this work\, we develop new nonequilibrium models for shock heated flows that are analytically consistent between kinetic and continuum scales and are based on recent ab-initio data\, applicable to large-scale CFD and direct simulation Monte Catlo (DSMC) simulations. \nNonequilibrium Hydrodynamics: The Navier-Stokes equations\, typically employed even at strong non-equilibrium conditions\, wherein thermodynamic fluxes such as stresses and heat flux vector are based on linear irreversible thermodynamics\, not be accurate in multiscale and multiphysics scenarios encountered in hypersonic flows. Similarly\, the Navier-Stokes equations are known to breakdown in rarefied (low density) gas flows. Therefore\, a new formalism is proposed to circumvent these issues\, which can also benefit\, hybrid methods that can combine continuum description using the Navier-Stokes equations and microscopic description\, necessary for efficient high-fidelity numerical simulations. Other wide range of physics problems such as nano-scale flows\, plasma physics modeling\, and general complex gas flows can also benefit from the proposed new non-equilibrium hydrodynamic formalism. \n  \nSpeaker: Dr. Narendra Singh \nBiography: Dr. Narendra Singh graduated with a PhD (and MS) in Aerospace Engineering (with minor in Mathematics and Chemistry) from University of Minnesota. Narendra obtained his undergraduate degree (with Honors) in MechE from IIT Bombay. In his doctoral thesis\, Narendra developed chemical kinetics models for DSMC and CFD using first principles-based approach. In addition\, Narendra (along with Prof.Agrawal) has developed higher order equations for rarefied and strong nonequilibrium flows\, known as O-13 and O-Burnett equations\, where O ‘refers’ to Onsager due to the consistency of equations with Onsager’s reciprocity principle. Narendra Singh did his 2 years postdoc in MechE at Stanford\, where his research spanned particle-laden flows\, carbon sequestration\, and ultrafast chemistry at SLAC. Currently\, he is a postdoc research associate at Center for Hypersonic\, UIUC\, and developing reduced order models for chemical kinetics. \n 
URL:https://aero.iisc.ac.in/event/nonequilibrium-reacting-flows-first-principles-based-modeling-for-chemical-kinetics-and-hydrodynamics/
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:20240313T073000
DTEND;TZID=Asia/Kolkata:20240313T203000
DTSTAMP:20260404T183424
CREATED:20240312T225849Z
LAST-MODIFIED:20240803T053029Z
UID:10000003-1710315000-1710361800@aero.iisc.ac.in
SUMMARY:[PhD Colloquium] 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 strength 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 and torsion and compression and 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)\, the 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 ordinary 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 these governing differential equations and boundary conditions. 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 as 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
URL:https://aero.iisc.ac.in/event/asymptotic-modelling-of-carbon-nanotube-cnt-and-cnt-reinforced-composite-structures-using-strain-gradient-formulations/
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:20240405T173000
DTEND;TZID=Asia/Kolkata:20240405T183000
DTSTAMP:20260404T183424
CREATED:20240405T112534Z
LAST-MODIFIED:20240802T165512Z
UID:10000004-1712338200-1712341800@aero.iisc.ac.in
SUMMARY:CyberSHM: A cyberphysical continuous monitoring technology for safety-critical structures
DESCRIPTION:Continuous monitoring is crucial for ensuring the proper functioning and longevity of operational structures in safety-critical applications. To address\, we are exploring the use of smart\, self-sensing structures that combine edge computing\, physics-informed and machine learning-enabled monitoring techniques. Of particular interest are thin-walled laminated composite structures with high-density cores and discontinuities that are especially challenging due to their complex waveguide behaviour. This talk will focus on the use of acousto-ultrasonic signals to monitor and interrogate such thin-walled structures for hidden barely visible damages. \nThe dispersion and wave scattering associated with these structures make traditional time-of-arrival (ToA) techniques ineffective for holistic damage identification. A singular focus on ToA results in under exploitation of several signal features needed for a multiclass representation of damages. Data-driven machine learning-based approaches are being explored which can map complex set of signal features to acoustic source characteristics. But rather than working as a black-box model for damage identification\, these must complement the physics-based model predictions to incorporate physical plausibility and thus establish a robust grey-box predictor. Physics-based dispersion characteristics is modelled with a semi-analytical approach which allows for interlaminar damage features to be incorporated into the model. The data-driven component focusses on training a high-dimensional Bayesian surrogate model which maps complex signal features in the time-frequency domain to the damage parameters such as location\, type and severity. Inverse identification is performed with a Bayesian approach which quantifies and incorporates measurement and model-form uncertainty into robust predictions of structural damage metrics and the associated confidence bounds. \nThe stated aim of continuous monitoring presents several challenges ranging from reducing the footprint of signal acquisition/processing hardware to combining cloud computing with edge computing to be deployed for conditioning and transmission of signals for real-time decision making. We conceptualise this as a Cyberphysical Structural Health Monitoring or a CyberSHM system which is an automated monitoring framework integrated with the internet and working collaboratively with human end-users. The study uses carbon-fibre composite panels with stiffeners as a test bench\, subjecting them to impact and fatigue loading and monitored with a CyberSHM system\, thus realising a generalized automated approach for online monitoring of thin-walled structures highlighting its effectiveness\, challenges and a futuristic vision of this technology. \n  \nSpeaker: Dr. Abhishek Kundu \nBiography: Dr Abhishek Kundu is a Senior Lecturer at the Computational Mechanics & Engineering AI research group at the Cardiff School of Engineering\, Cardiff University\, UK and an elected member of the Royal Aeronautical Society. His research interests span the fields of structural health monitoring (SHM)\, stochastic structural dynamics\, uncertainty quantification\, machine learning and Bayesian identification. His main contribution lies in efficient computational techniques for the study of stochastic structural dynamics systems and control and data-driven approaches for SHM. He completed his PhD from Swansea University as Zienkiewicz scholar in 2014. Dr Kundu has authored more than 50 scientific publications and was awarded the best paper at the European Workshop on Structural Health Monitoring (EWSHM 2018). Amongst his main research engagements\, he has been the recipient of Royal Academy of Engineering’s Industrial Fellowship with Airbus and currently serves as the principal investigator in the EPSRC funded project on CyberSHM.
URL:https://aero.iisc.ac.in/event/cybershm-a-cyberphysical-continuous-monitoring-technology-for-safety-critical-structures/
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:20240418T213000
DTEND;TZID=Asia/Kolkata:20240418T223000
DTSTAMP:20260404T183424
CREATED:20240418T112845Z
LAST-MODIFIED:20240803T053223Z
UID:10000005-1713475800-1713479400@aero.iisc.ac.in
SUMMARY:[PhD Colloquium] A class of vector fields for path following guidance
DESCRIPTION:With rapidly evolving application scenarios\, Unmanned Aerial Vehicles (UAVs) are often desired to autonomously follow predefined paths. Prospective path following guidance methods should cater to the dynamic capability of the UAV\, curvature variation along the path\, and provide accurate performance while utilizing\, preferably\, a computationally inexpensive guidance logic. This thesis presents a class of vector fields addressing a variety of path following guidance problems. \nThe first part of the thesis considers constant curvature paths\, namely\, straight lines and circular orbits. The key idea is to generate the commanded UAV course angle as a vector field based on the instantaneous UAV position. The vector field logic uses an arcsine shaping function based on the UAV position with respect to the desired path. A stability analysis guarantees asymptotic convergence of the UAV position error to zero. A detailed comparative study with a popular approach demonstrates that the proposed method significantly reduces the maximum curvature and the total control effort along the guided trajectory. Numerical simulation studies consider a second-order course hold autopilot\, first-order airspeed control and different UAV initial conditions to demonstrate the effectiveness of the proposed guidance method. \nThe second part of the thesis considers scenarios wherein the path exhibits variation in its curvature. First case considers an elliptic path following scenario\, and a course angle guidance command is proposed which encompasses path convergent and path tangential components. The path convergent term is deduced using an arcsine shaping function of the UAV position error with respect to the path\, while the tangential component is obtained using the slope information of the path. The second path following case considers paths described explicitly as y = f(x). Therein\, again the course angle guidance command comprises path-tracking and path-attracting elements. Subject to the proposed guidance methods\, asymptotically converging behaviour of the UAV position error is deduced using Lyapunov stability theory. Extensive simulation studies are carried out with several UAV initial positions for following elliptic\, sinusoidal\, and parabolic paths. \nNext\, the thesis introduces rectangular boundary surveillance guidance using Lamé curve paths. Geometric properties of the Lamé curve paths are analysed\, and an efficient Lamé curve path-based circumscription of a rectangular boundary is proposed. Considering a given UAV maximum turn rate\, a comparative analysis highlights that the proposed Lamé curve path offers significantly reduced path length in circumscribing a rectangular boundary as compared to widely used elliptic circumscription. Further\, a vector field guidance method is introduced to follow the Lamé curve path\, and its stability properties are established. Numerical simulations include sample scenarios with several UAV initial conditions and comparative studies with different rectangular dimensions. \nUsing an indoor motion capture facility and a quadrotor UAV platform\, the last part of the thesis presents experimental validation studies for the proposed guidance methods. Flight trials consider a variety of constant and variable curvature paths and demonstrate the effectiveness of the proposed guidance methods. \nOverall\, the proposed guidance methods present simple\, analytic\, and easily computable path-following logic that utilize only the UAV position information. Deterministic performance guarantees and extensive validation studies further add to the merit of the proposed guidance solutions. \n  \nSpeaker: Amit Shivam
URL:https://aero.iisc.ac.in/event/a-class-of-vector-fields-for-path-following-guidance/
LOCATION:Auditorium (AE 005)\, Department 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:20240527T153000
DTEND;TZID=Asia/Kolkata:20240527T163000
DTSTAMP:20260404T183424
CREATED:20240527T042855Z
LAST-MODIFIED:20240803T053109Z
UID:10000006-1716823800-1716827400@aero.iisc.ac.in
SUMMARY:[PhD Colloquium] 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
URL:https://aero.iisc.ac.in/event/on-the-nature-of-transonic-buffet-in-a-finite-span-wing/
LOCATION:AE Auditorium
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:20240531T153000
DTEND;TZID=Asia/Kolkata:20240531T170000
DTSTAMP:20260404T183424
CREATED:20240531T052920Z
LAST-MODIFIED:20240802T115823Z
UID:10000007-1717169400-1717174800@aero.iisc.ac.in
SUMMARY:Re-scaling of properties in wall-bounded turbulent flows
DESCRIPTION:Max Plank is supposed to have said that Science progresses one funeral at a time. Prof. Sreenivasan will discuss the conventional wisdom of wall-bounded turbulent flows while keeping in mind the modified thought that even funerals are sometimes not enough. \n  \n  \nSpeaker: Prof. K.R. Sreenivasan \nBiography: Prof. Katepalli R. Sreenivasan is currently the Satish Dhawan Visiting Professor at IISc. He is a University Professor at New York University (NYU)\, a distinguished title conferred upon him for his interdisciplinary work that reflects exceptional breadth. He holds Eugene Kleiner Chair Professorship for Innovation with affiliations to NYU’s Physics Department\, Courant Institute of Mathematical Sciences\, and Tandon School of Engineering. He was the Dean of the NYU Tandon School of Engineering. Prior to joining NYU\, he was the Director of the International Centre for Theoretical Physics in Trieste\, Italy\, and professor at University of Maryland and Yale. He is also a Distinguished Alumnus of IISc. Prof. Sreenivasan is an expert in fluid dynamics and turbulence\, and his research spans across a few other areas of applied physics. He has held several administrative positions\, won a number of prestigious international awards\, and is an elected member of numerous academies across the globe including the US National Academy of Sciences and the Indian Academy of Sciences.
URL:https://aero.iisc.ac.in/event/re-scaling-of-properties-in-wall-bounded-turbulent-flows/
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:20240614T160000
DTEND;TZID=Asia/Kolkata:20240614T170000
DTSTAMP:20260404T183424
CREATED:20240614T061338Z
LAST-MODIFIED:20240803T061531Z
UID:10000015-1718380800-1718384400@aero.iisc.ac.in
SUMMARY:Design and characterization of periodic scatterers for noise insulation
DESCRIPTION:The array of periodic scatterers is known as sonic crystal at present and sonic crystal is the most cost-effective solution for a “noise barrier” because of its acoustic attenuation due to size\, geometry\, and periodic arrangement of scatterers. Porous materials that are commonly used for sound absorption have poor sound insulation capability. In this work\, rigid scatterers are installed periodically inside porous materials to improve their transmission loss (TL) with the Bragg diffraction. The Delany-Bazley impedance model is used to model the porous material and the transfer matrix method is adopted to calculate the TL of the mixed structure in a duct. Simulation results with a different number of scatterers and porous materials with different airflow resistivity show that the TL of porous materials can be increased significantly with periodically arranged scatterers. The decoupled analysis reveals that the TL of the mixed structure is larger than the sum of the TL of individual components in most frequency bands\, except that around the first Bragg resonance frequency. Afterwards\, the insertion loss (IL) of two types of finite size structures constructed by installing two parallel porous sheets within rows of periodic scatterers is investigated in free field. Next\, the free field insertion loss (IL) and echo reduction (ER) are calculated for finite size periodic scatterers via time domain simulations in a room environment where the walls of the room are acoustically reflective. A spectrally dense short pulse is used as a sound source and the time domain pulse separation technique is devised to calculate the IL and ER of finite size periodic scatterers. The key discovery of the research is that the calculated IL and ER of periodic cylindrical scatterers in a room environment agree to results obtained from the free field simulations which are also imitable experimentally. Next\, the experiments are conducted in a room environment with periodic cylindrical scatterers. A loudspeaker is used as a sound source. The signal synthesis technique is demonstrated to generate the desired short pulse from a loudspeaker for measurement in given environment followed by measurements which agree to simulation results. \n  \nSpeaker: Dr. Dibya Prakash Jena \nBiography: Dr. Dibya Prakash Jena is an expert in artificial metamaterials\, condition monitoring\, and acoustics\, vibration and noise control having wide experience in industry and academia. He has been awarded the DIN Young Visiting Fellowship 2022 and the Honorary Research Fellow of the University of Technology Sydney. He has over 32 journal publications\, 4 patents\, 2 book chapters and 12 conference publications.
URL:https://aero.iisc.ac.in/event/design-and-characterization-of-periodic-scatterers-for-noise-insulation/
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:20240624T110000
DTEND;TZID=Asia/Kolkata:20240624T120000
DTSTAMP:20260404T183424
CREATED:20240624T052703Z
LAST-MODIFIED:20240803T060320Z
UID:10000008-1719226800-1719230400@aero.iisc.ac.in
SUMMARY:[PhD Colloquium] Effect of Interface Roughness in Adhesively Bonded CFRP Joints – Experimental and Numerical Studies
DESCRIPTION:This thesis 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 using Micro-System Analyzer. 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. A band of NDE techniques was utilized to evaluate the effects of surface roughness in Adhesively Bonded Joints(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). The primary objective of evaluating the effect of interface surface roughness on the strength of adhesively bonded composites has been addressed adequately\, which has yielded very significant\, interesting and effective outcome. Further research along the same line can help in developing an effective and important NDE tool for health monitoring of adhesively bonded joints. \nSpeaker: MANE LAXMIKANT SARJERAO
URL:https://aero.iisc.ac.in/event/effect-of-interface-roughness-in-adhesively-bonded-cfrp-joints-experimental-and-numerical-studies/
LOCATION:AE 105
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:20240627T153000
DTEND;TZID=Asia/Kolkata:20240627T163000
DTSTAMP:20260404T183424
CREATED:20240626T053743Z
LAST-MODIFIED:20240803T060237Z
UID:10000009-1719502200-1719505800@aero.iisc.ac.in
SUMMARY:[MTech(Res) Colloquium] Inflatable aerodynamic decelerators for atmospheric re-entry
DESCRIPTION:Atmospheric re-entry is the most challenging part of human space flight. In the re-entry phase of flight\, the crew module (or re-entry vehicle) is required to bring the onboard astronauts from orbital velocities\, which are in the range of several kilometers per second\, to near-zero velocity at touchdown\, in a safe and controlled manner. The crew module experiences severe aerodynamic heating and large deceleration loads (g-forces) as it descends into the atmosphere at high hypersonic velocities. Re-entry poses formidable engineering challenges\, and also places great physical and mental demands on astronauts.\n\nThe re-entry crew module of the Gaganyaan space program follows a positive L/D (aerodynamic lift to drag ratio) descent trajectory that is established through an offset CG (center of gravity) design. Reaction thrusters provide roll\, pitch\, and yaw control. The design and philosophy of the Gaganyaan crew module is similar to that of the Soyuz crew module. However\, the Soyuz crew module additionally incorporates a ballistic descent mode for use during off-nominal (emergency) situations. Ballistic descent requires a zero L/D condition\, which is achieved by Soyuz through a continuous rotation of the crew module at the rate of 13 degrees per second. The Gaganyaan crew module does not presently incorporate such a feature.\n\nThe present effort is aimed at developing the concept of inflatable aerodynamic decelerators (IADs) to achieve standby ballistic mode capability\, and to also reduce deceleration and aerodynamic heating loads during routine re-entry (or entry to other planetary atmospheres). The aerodynamic characteristics of a canonical re-entry body – crew module with an IAD – at hypersonic Mach numbers is studied through flow computations (using Reynolds-averaged Navier–Stokes equations) and wind tunnel experiments. The L/D of the re-entry body is varied by changing its CG location\, which is achieved by altering the relative position of the IAD with respect to the crew module. The default re-entry body configuration is set for a positive L/D\, which significantly limits deceleration and aerodynamic heating loads. The L/D is brought to zero to achieve ballistic re-entry in an off-nominal situation. Using the aerodynamic data obtained from flow computations and experiments\, the advantages of using an IAD for re-entry are quantitatively assessed and demonstrated through trajectory analysis. A preliminary engineering feasibility study for the proposed concept is also presented in this thesis.\n\nSpeaker: Gp. Capt. Prasanth Balakrishnan Nair (ISRO Human Space Flight Centre)
URL:https://aero.iisc.ac.in/event/mtechres-colloquium-inflatable-aerodynamic-decelerators-for-atmospheric-re-entry/
LOCATION:AE Auditorium
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:20240627T153000
DTEND;TZID=Asia/Kolkata:20240627T163000
DTSTAMP:20260404T183424
CREATED:20240627T053941Z
LAST-MODIFIED:20240803T060152Z
UID:10000010-1719502200-1719505800@aero.iisc.ac.in
SUMMARY:[MTech(Res) Colloquium] Sub-mesoscale modeling of woven fabrics using VAM-based geometrically-exact beam model
DESCRIPTION:In this work\, a sub-mesoscale model of a woven fabric is developed using finite element methods. The yarns are modeled as beam elements that move freely in space and undergo large deformations and rotations. The geometrically-exact beam theory (GEBT) used to model composite beams of arbitrary cross sections is considered to model the yarns. The variational asymptotic method (VAM) offers the advantage of modeling beams of arbitrary cross sections. A surface-to-surface contact model is developed\, considering that the contact occurs at a point on the surface. The robustness of the contact model is tested by designing a patch test. The mesoscale model is validated using experimental results of biaxial tests performed on a plain glass weave woven fabric. The biaxial simulation is performed by varying the number of yarns in the mesoscale model to study the behavior of the model and demonstrate a representative volume element (RVE). The yarns are made up of fibers twisted together. An isotropic model is an approximation that works well on the mesoscale\, but a more general model is needed to include fiber-level information. Most microscale models use technologically expensive micro-CT scans. There are powerful homogenization techniques\, such as variational asymptotic homogenization (VAH)\, that can be leveraged to develop homogenized properties of the yarn by including fiber-level information. The use of VAH includes more physics into the model with minimal effort. A novel alternative model to a woven fabric is developed using VAM to include microscale information. The tools like cross-sectional analysis\, GEBT\, and VAH are used to study the behavior of woven fabrics with different coatings. The model can be extended by introducing friction between yarns in the contact. Further\, the uncertainty in the input parameters can be quantified by propagating the uncertainty through the system using uncertainty quantification (UQ) techniques. \n  \n\nSpeaker: R ADHITHYA
URL:https://aero.iisc.ac.in/event/mtechres-colloquium-sub-mesoscale-modeling-of-woven-fabrics-using-vam-based-geometrically-exact-beam-model/
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:20240705T163000
DTEND;TZID=Asia/Kolkata:20240705T173000
DTSTAMP:20260404T183424
CREATED:20240705T061014Z
LAST-MODIFIED:20240803T061218Z
UID:10000014-1720197000-1720200600@aero.iisc.ac.in
SUMMARY:[PhD Defense] Wave Propagation in Bio-Inspired Inhomogeneous waveguides for Impact  Mitigation Applications
DESCRIPTION:Decades of research aim to shield structures and people from impact and  shock\, mitigating damage and traumatic brain injuries. The development  of novel structures to absorb energy and reduce stress waves in  structures is indispensable. This thesis derives inspiration from the  biological structure of the woodpecker beak. The woodpecker pecking  generates very high amplitude impact loads causing stress waves to  propagate in its inhomogeneous beak structure\, without sustaining any  brain injury. The main aim of this thesis is to mimic such inhomogeneous  structures in the critical mechanical systems that require impact  mitigation. This dissertation focuses on comprehensive investigation of  computational and experimental wave propagation analysis in such  bio-inspired inhomogeneous structures\, which are often periodic\,  symmetric or anti-symmetric about the midplane\, while exhibiting both  the elastic and viscoelastic material behaviour. Importantly\, the goal  of these new bio-inspired designs is to control the wave propagation in  terms of increased attenuation\, reduction of group speeds and increase  in dispersion. \nFirstly\, the superconvergent finite elements (FE) for longitudinal and  flexural wave propagation analysis in the symmetrical sinusoidally  corrugated bio-inspired structures considering both elastic and  viscoelastic material models are developed\, whose accuracy is validated  using Abaqus. In addition to the wave propagation studies\, static and  free vibration analyses are also carried out in such structures. Next\,  the governing differential equations and the superconvergent FE are  derived for the wave propagation analysis in the shear-deformable  waveguides with anti-symmetric sinusoidal corrugations that introduce  coupling between the wave modes\, and it is validated using the  conventional FE. The study resulted in the development of the  methodology to easily manipulate wave propagation characteristics. Thus\,  a few optimised waveguide configurations that can reduce both group  speeds and wave amplitudes are presented. \nDue to the advantage of modeling viscoelasticity in the frequency  domain\, the frequency domain finite elements based on the spectral FE  are developed for both elastic and viscoelastic structures. Exploiting  the periodicity of the bio-inspired structures\, the dispersion plots are  obtained using the Floquet-Bloch theorem and the transfer matrix method.  The spectral FE and Bloch theorem-eigenvector methods are then used to  obtain the time-history responses in the semi-infinite as well as finite  structures. For dynamic and wave propagation analysis of viscoelastic  structures in the time domain\, a new direct time integration scheme is  also proposed. The stability analysis of the proposed scheme is carried  out using the spectral technique as well as the von Neumann stability  criteria. The responses obtained using the proposed time integration  scheme for various structures are validated with a commercial finite  element code. \nBased on the conducted research\, facesheets for honeycomb sandwich  structures as a practical application for blast wave mitigation are  developed. The suture structures in the facesheets are obtained with the  multi-objective structural optimization method using genetic algorithm  (NSGA-II)\, wherein the developed viscoelastic FE formulation is used.  The performance of this optimized suture-based face sheet is  experimentally tested in a vertical shock tube to validate the results  obtained using Abaqus.\nIn summary\, this thesis offers a multidisciplinary approach in  investigating and understanding wave propagation in the bio-inspired  inhomogeneous structures and its relevance to impact mitigation. \n  \n  \nSpeaker: Manish Suresh Raut
URL:https://aero.iisc.ac.in/event/phd-defense-wave-propagation-in-bio-inspired-inhomogeneous-waveguides-for-impact-mitigation-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/2024/04/Thesis-Colloquium-Defence.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20240712T113000
DTEND;TZID=Asia/Kolkata:20240712T123000
DTSTAMP:20260404T183424
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:20260404T183424
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:20260404T183424
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:20260404T183424
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:20260404T183424
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:20260404T183424
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:20260404T183424
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:20260404T183424
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:20260404T183424
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:20260404T183424
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:20260404T183424
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:20260404T183424
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:20260404T183424
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:20260404T183424
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:20260404T183424
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:20260404T183424
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:20260404T183424
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:20260404T183424
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
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