Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 46 for “"Elastic Energy"”.
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Recovering elastic energy in a single-legged hopping robot
… is Ek/Ein, the ratio of the systems peak kinetic energy to the energy input into it over one gait cycle. In this project, I create an analytical model of a hopping robot and a corresponding physical prototype that will serve as an experimental platform to investigate the relationship between Ek …
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Biomechanics of Hierarchical Elastic Systems
<p>Elastic energy plays important roles in biology across scales, from the molecular to organismal level, and across the tree of life. The ubiquity of elastic systems in biology is partly due to the variety of useful functions they permit such as the simplification of motor control in running …
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Energy loss and theoretical uncertainties in small quark-gluon plasmas
… this thesis is to systematically improve current energy loss models, particularly in how they pertain to small systems. We present a perturbative Quantum Chromodynamics (pQCD) based energy loss model which receives small system size corrections to both the radiative and elastic energy loss, and …
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An investigation of the mechanics of an actin spring
… cells rely on the conversion of potential energy into mechanical work. One such example is the dramatic process involving the acrosome reaction of Limulus sperm, whereby a 60-im long bundle of actin filaments straightens from a coiled conformation to extend out of the cell in five seconds. …
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Optimization of an Unfurlable Space Structure
… fully deployed configuration and minimal strain energy in its stowed configuration. The optimized stowed structure is then deployed in simulation. The structure consists of a rectangular panel that tightly wraps around a central cylindrical hub for release in space. It is desired to minimize …
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Empirical Multiphase Model for Strength Evolution of High-Chromium Steel Alloys
… property evolution through phenomenological energy-strength relationships. A comprehensive six-month isothermal ageing study at 500 °C established the experimental foundation, revealing characteristic strength evolution: 47.9% hardening (695 to 1028 MPa, 0-504 hours), 13.6% softening to 873 …
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Structural and Elastic Properties of Degenerate SnO Monolayers at Finite Temperature
… cell at zero temperature and a charge-tunable energy barrier that leads to a thermally-controllable structural phase change. Doped SnO monolayers with rectangular degenerate unit cells give rise to two-dimensional multiferroicity. Their two-dimensional elastic energy landscape adopts a basic …
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Aging Effects on Arterial Mechanics and Matrix Remodeling
<p>Large elastic arteries are a composite structure composed of cells and extracellular matrix proteins. Passive arterial mechanical behavior is determined by the composition of extracellular matrix proteins, in particular elastin and collagen. Elastin provides reversible elasticity to the large …
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Comparison of user metabolic efficiency between traditional and spring assisted leveraged freedom chair models
… were performed to determine how the use of an elastic energy storage mechanism on the Leveraged Freedom Chair would affect the rider's metabolic efficiency. For this test, elastic bands were attached to the levers, and the rider's heart rate was recorded as he rode multiple lengths of a field …
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Ground movements due to excavation in clay: physical and analytical models
… geometry. Validation of the conservation energy principle was carried out for the undrained excavation process. The total loss of potential energy was shown to be balanced by the total work done in shearing and the total elastic energy stored in structures with an error term of 30%. An …
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Observing and modelling the legless jumping mechanism of click beetles for bio-inspired robotic design
… three consecutive stages: the pre-jump stage (energy storage), and the take-off and airborne stages (energy release). Morphological measurements of the previously mentioned species as well as three additional species, namely Agriotes sp., Athous sp. and Lacon discoideus are taken, and isometric …
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Design, microstructure and mechanical properties of new Ti-based alloys
… dominant β phase structure exhibits the lowest elastic modulus (92 GPa) and highest plasticity (40%). In Ti-7Fe-xNb (x= 0, 1, 4, 6, 9, 11 wt%), it was observed that only Ti-7Fe-11Nb alloy shows single β phase microstructure, while others are comprised of β and α″ phases. Moreover, Nb addition up …
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Degradation study of AIGaN/GaN HEMT through electro-thermo-mechanical calculations and thermo-reflectance measurements
… gives rise to large changes in strain field and elastic energy density in the transistors under the pinch-off conditions. Most previous work have studied the inverse piezoelectric effect on device degradations, however, quantitative analysis of this failure mechanism is still needed. In this …
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Design of a quasi-passive parallel leg exoskeleton to augment load carrying for walking
… ankle springs are employed to store and release energy throughout the gait cycle. To reduce knee muscular effort, a variable damper is implemented at the knee to support body weight throughout early stance. In this thesis, I hypothesize that a quasi-passive leg exoskeleton of this design will …
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Adaptive data analysis for damage detection and system identification in civil infrastructure
… years, more structures are loaded beyond their elastic conditions and may thus experience damage in the years to come. Even if structures remain elastic, energy dissipation devices installed on structures often reveal hysteretic behaviors under earthquake loads. Therefore, it is imperative to …
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Dynamics and statics of actin assemblies
The conversion of chemical energy into mechanical forces that powers cell movements is a ubiquitous theme across biology. The acrosome reaction of Limulus sperm is a simple example of such a dynamical transformation where a 60 [mu]m-long crystalline bundle of actin filaments, tightly cross-linked …
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Interaction of High Aspect-Ratio Micro-Pillars with Wall Turbulence
… wall turbulence is presented. Micro-pillars are elastic, hair-like microstructures which have been inspired by naturally occurring examples like lateral line sensors in fish and air flow sensors in bats. The objective of this thesis was two fold: to develop a manufacturing process for consistent …
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Beetle exoskeletal structure and surfaces determine specialized functions: Two case studies
… the beetle body in brace position, while elastic energy is being stored in other body parts. The work confirms that the unique morphology of the peghold results in a stiff and robust structure that is able to withstand significant energy storage without material failure while maintaining …
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Nanoindentation Under Dynamic Conditions
… the strain rate dependence of the superelasticity of nickel-titanium was probed over a range of temperatures. Similar trends in elastic energy ratios with temperature were observed with the largest elastic proportions occurring at the Austenite finish transformation temperature. Multiple …
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A study of biomechanical variables in the countermovement jump and the drop jump performed by female intercollegiate athletes
… percentage of simultaneity and utilized stored elastic energy were not significantly different for either jump condition or sport group; and (d) peak jump heights were similar for jump conditions and sport groups. Descriptive statistics were computed on demographic data and five kinematic …
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