32 research outputs found
Strain analysis in glenohumeral capsule through finite element modelling
No full textThe injury mechanics and strain distribution in the glenohumeral capsule at a particular joint angle have been studied extensively. However, there is a lack of information on the strain distributions in the capsule under complex joint angles, i.e, during the activities of daily living (ADL). To investigate the mechanical response of the capsule under the kinematics of the forward reach, a subject specific finite element model of the glenohumeral joint with the capsule was developed. Since the mechanical properties of the capsule under multiaxial loading were unknown we proposed an inverse finite elements based optimization routine to determine the material coefficients of the capsule. Several constitutive material models were evaluated to identify feasibility of convergence for the complex loading associated with physiological tasks. We established limits for the material coefficients of the Mooney-Rivlin model used to model the capsule. The Mooney-Rivlin model with the material coefficients C1 = 6, C10 = 6.5, and D1 = 0.12 converged for around 50% of the cycle. The results also suggest that the peak strain occurred on the inferior aspect of both the anterior and posterior side of the capsule. This work serves as the basis for future comparisons of material models and can be extended to other activities of daily living.Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2021-08-01The student, Vineeth Bodapati, accepted the attached license on 2019-07-18 at 20:31.The student, Vineeth Bodapati, submitted this Thesis for approval on 2019-07-18 at 20:40.This Thesis was approved for publication on 2019-07-19 at 11:25.DSpace SAF Submission Ingestion Package generated from Vireo submission #14386 on 2019-11-26 at 13:06:21Made available in DSpace on 2019-11-26T20:49:34Z (GMT). No. of bitstreams: 2
BODAPATI-THESIS-2019.pdf: 4325109 bytes, checksum: 45dad2318f1da51d69b3a2ab6d7525a5 (MD5)
LICENSE.txt: 4213 bytes, checksum: 878d0508550aa0a644edfcc74a55ce0c (MD5)
Previous issue date: 2019-07-19Embargo set by: Seth Robbins for item 112986
Lift date: 2021-11-26T20:49:41Z
Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemU of I Only Restriction Lifted for Item 112986 on 2021-11-27T10:15:30Z
Computational Modelling of the Oryon Watermill: A Nested Fluid-Structure Interaction Problem with Non-Smooth Dynamics
No full textThe current research aims to numerically predict the performance characteristics of the Oryon Water Mill. The simulation mechanism to be developed, begins at the structural solver part of a partitioned FSI solver, upon which the unique functional characteristics of the turbine are embedded. The modelling is carried out to account for the turbine’s functional characteristics like, multiple nested rigid body FSI dynamics, non-smooth dynamics and lamella partial torque contributions. The solver is built to resolve the turbine dynamics in two dimensions and re-scale the final result with respect to the turbine core height. The results of the simulation show the predicted torque to be of similar trend as that of the experimental data collected by MARIN, while being an over-prediction by a factor of two. The optimal performance range of the turbine is predicted within an error bound of 0.1RPS. The overprediction of the torque is considered to be a result of the 2D solution not accounting for the flow leakage in the third and unaccounted for direction. The time variant fluid solution is found to be unstable due to the spikes observed in the torque time signal and is a consequence of the perfect momentum sink assumption employed in the modelling of the lamella’s non-smooth dynamics. The lamella dynamics are observed to not convergence to fully periodic behaviour and the sensitivity of the lamella’s dynamics is considered to be the root cause. The velocity Verlet based structural solver does not provide fluid-structure coupling iterations, the inclusion of which, could improve the stability of the fluid solution.This endeavour establishes a foundation for the predictive numerical simulation of the OWM in the form of baseline numerical simulation results and a developed simulation framework
A Numerical Study of Changes to Flow Organization and their Prognostic Measures
No full textFlow induced self-oscillations cause acoustic pressure oscillations of large amplitude in pipe flows. If Reynolds number is treated as a parameter, these floinduced oscillations occur only at discrete and critical values of Reynolds number. However, for a small range of Reynolds numbers around such a critical value, such periodic oscillations may appear intermittently. If intermittency, which is a precursor to these self-oscillations, can be detected, prediction of an impending instability may be possible.
In experiments done by Vineeth and Sujith (Int. J. Aeroacoustics, 2016) on flow in a duct orifice arrangement, where flow enters through the duct inlet, and leaves into the atmosphere through the orifice exit, “whistling” was observed at a Reynolds number of 4200 (based on the orifice thickness and flow speed within the orifice), where large amplitude pressure oscillations were observed. At slightly lower Reynolds numbers, bursts of relatively smaller amplitudes of pressure oscillations were observed to appear intermittently.
For a similar configuration, Large Eddy Simulations (LES) have been carried out with explicit filtering as a sub grid scale model here. Both whistling and intermittency are observed in the simulations. As air flows from the duct into the orifice, it turns sharply around the corner at the duct orifice interface. Due to this sharp turn, flow separation occurs, and hence, a shear layer is formed at the mouth of the orifice. The mechanism of whistling is found to be this shear layer within the orifice flapping about and hitting the trailing edge of the orifice periodically, thus causing the shear layer to break and roll up into a vortex. At Reynolds numbers where intermittency is observed, the shear layer is found to very mildly come in contact with the edges of the orifice walls, thus disturbing it.
In the simulations, time series data of pressure are recorded at various probe locations. In a given time series, if scale invariance behaviour exists, it can be quantified by measuring the Hurst exponent. The numerical value of the Hurst exponent is an index of “long range or short range dependence” in a time series. Hurst exponent is measured in the time series data obtained. It is found to drop to zero as the flow approaches the state of a self-sustained oscillation, since the growth rates of all the long term as well as short term trends in the time series vanish. A loss of multifractality in the time series is also observed as the flow approaches whistling.
As a part of the this thesis, new, split high resolution schemes of high order are designed following the Hixon Turmel Proposal
Who Manages What? Covid-19 and the Centre-State Division of Responsibilities in Indian Democracy
No full textThe Constitution of India has provisions of separation of power in order to facilitate the smooth functioning of the federal structure consisting of the central and state governments. Accordingly, a list has been illustrated in the Constitution of India where the Centre and State governments will have autonomous or shared ownership and responsibilities. As per this list, the subject of health comes under the purview of the state government. In this article, the author explores various aspects associated with the COVID-19 pandemic that has necessitated the central government to step into the domain of health, which is a state subject
CONSUMER ATTITUDES AND PREFERENCES IN THE TRANSITION TO ELECTRIC VEHICLES
No full textThe global transition towards electric vehicles (EVs) has sparked significant interest in Kerala, a state at the forefront of India in e-mobility revolution. The study analyses consumer attitudes and preferences towards electric vehicles transition in Kerala, aiming to understand the factors influencing their willingness to transition from conventional engine vehicles. Through the surveys and interviews carried out in the study reveal that Kerala's consumers are enthusiastic about electric vehicles driven by concerns about environmental sustainability, fuel efficiency, and government incentives. However, range anxiety, high upfront costs, and charging infrastructure limitations remain significant barriers. The findings suggest that targeted interventions, such as investing in charging infrastructure, offering attractive financing options, and promoting awareness campaigns, can accelerate electric vehicles adoption in Kerala. This study contributes to the understanding of consumer behavior in the context of sustainable transportation and informs policy and marketing strategies to facilitate a smoother transition to electric vehicles in the region
Beyond Empire: Postcolonialism and Mission in a Global Context, By Jonathan Ingleby. Milton Keynes, UK, Author House 2010. Pp. xix + 279. £13.50.
No full text
VerilogA Modelling of Programmable Metallization Cells
No full textabstract: There is an ever growing need for larger memories which are reliable and fast. New technologies to implement non-volatile memories which are large, fast, compact and cost-efficient are being studied extensively. One of the most promising technologies being developed is the resistive RAM (ReRAM). In ReRAM the resistance of the device varies with the voltage applied across it. Programmable metallization cells (PMC) is one of the devices belonging to this category of non-volatile memories.
In order to advance the development of these devices, there is a need to develop simulation models which replicate the behavior of these devices in circuits. In this thesis, a verilogA model for the PMC has been developed. The behavior of the model has been tested using DC and transient simulations. Experimental data obtained from testing PMC devices fabricated at Arizona State University have been compared to results obtained from simulation.
A basic memory cell known as the 1T 1R cell built using the PMC has also been simulated and verified. These memory cells have the potential to be building blocks of large scale memories. I believe that the verilogA model developed in this thesis will prove to be a powerful tool for researchers and circuit developers looking to develop non-volatile memories using alternative technologies.Dissertation/ThesisMasters Thesis Electrical Engineering 201
A Smoothing Algorithm for the Dual Marching Tetrahedra Method
No full textabstract: The Dual Marching Tetrahedra algorithm is a generalization of the Dual Marching Cubes algorithm, used to build a boundary surface around points which have been assigned a particular scalar density value, such as the data produced by and Magnetic Resonance Imaging or Computed Tomography scanner. This boundary acts as a skin between points which are determined to be "inside" and "outside" of an object. However, the DMT is vague in regards to exactly where each vertex of the boundary should be placed, which will not necessarily produce smooth results. Mesh smoothing algorithms which ignore the DMT data structures may distort the output mesh so that it could incorrectly include or exclude density points. Thus, an algorithm is presented here which is designed to smooth the output mesh, while obeying the underlying data structures of the DMT algorithm.Dissertation/ThesisM.S. Computer Science 201
