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 24 for “"resistance changes"”.
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Monitoring breathing with smart fabrics
… the need for numerous embedded components. Resistance changes from thoracic expansion are acquired in real time using Keysight EDU34450A Digital Multimeter and compared against (i) a force-sensing belt and (ii) audio-based respiration detection. Results show close alignment in breath timing …
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Robust adaptive control of induction machines using the L1 control scheme
… nonlinear, changing flux dynamics. Also, rotor resistance changes with temperature as the machine is heated due to normal use, resulting in more parametric uncertainty. The proposed control scheme will cause the motor to track a desired reference model behavior, even in the presence of these …
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Anomalous X-ray transmission changes in copper crystals on electron irradiation at 14 K
… at 14 Kwith 3 MeV electrons, Simultaneous resistance measurements were taken on high purity copper wires, The measured intensity changes for (111), (222), (333), (220), (200), and (400) reflecting planes were investigated at intervals during the irradiation, Annealing studies at 22 K, 37 K, …
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Mechanical relaxations, spin glasses and 1/f resistance noise
Two experiments related to 1/f resistance noise will be described in this thesis. The first is measurements of the anelastic piezoresistance in thin films of bismuth, niobium and iron to demonstrate a connection between mechanical anelastic relaxations and electrical 1/f noise from the motion of …
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Mechanical relaxations, spin glasses and 1/f resistance noise
Two experiments related to 1/f resistance noise will be described in this thesis. The first is measurements of the anelastic piezoresistance in thin films of bismuth, niobium and iron to demonstrate a connection between mechanical anelastic relaxations and electrical 1/f noise from the motion of …
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Mechanical and Electrical Characterization of Hybrid Carbon Nanotube Sheet-Graphene Nanocomposites for Sensing Applications
… and their composites, in which electrical resistance changes when mechanical deformation is applied facilitates their use in sensing applications.</p> <p>In this work, carbon nanotube sheet- epoxy nanocomposites with the matrix modified with various contents of coarse and fine graphene …
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A Schottky-to-Ohmic Transition in Epitaxial Ferroelectric Hafnia Devices
… two mechanisms actively being explored to drive resistance change in hafnia based devices. This thesis explores the interplay between interfacial redox chemistry and ferroelectricity and how these influence the resistance switching behaviour in epitaxial hafnia films. A device stack is engineered …
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Piezoresistive UHMWPE WMCNT Sensors for Instrumented Total Knee Replacements
… insulating UHMWPE to a nano-composite whose resistance changes with the applied stress. A steel mold and a two-stage compression molding process were developed to instrument and hermetically seal the embedded sensors within the tibial insert. As the sensors were made from the same material as …
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Design and analysis of wearable conductive fiber sensors for continuous multi-axis joint angle measurements
… skin-tight fabrics surrounding a joint is used. Resistance changes across these conductive fibers are measured, and directly related to specific single or multi-axis joint angles through the use of a nonlinear predictor after an initial, one-time calibration. These wearable sensors are …
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Tactile sensors based on soft polymers
… cubes of CB/PDMS revealed that the material's resistance increases monotonically with strain and that CB/PDMS have similar sensitivities to tension and compression across different CB concentrations. Shear sensitivity, however, was relatively poor and inconsistent between samples. To overcome …
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Functional Materials and Device Concepts for Magnetic Sensing, Gas Detection and Energy Harvesting
… examines metal-oxide (MOX) gas sensors, whose resistance changes when semiconducting metal oxides interact with target gases. Nanostructuring, surface doping, and polymer functionalization are investigated to enhance sensitivity, selectivity, and humidity resistance. Particular emphasis is …
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Towards structural health monitoring in carbon nanotube reinforced composites
… fiber substrate. Mechanical load and electrical resistance were simulataneously measured using three different probes configurations with respect to the tensile direction that measured either surface or through thickness resistance changes. Measurements were taken near and away from the stress …
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Radiation damage assessment of atomically thin membranes
… to the environment. This device minimizes flow resistance on both sides, allowing for membrane resistance changes to be appropriately assessed. This apparatus also measures less than 5 % error between trials on the same membrane, which can be improved with more data collection for each transport …
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Field-structured chemiresistors : tunable sensors for chemical-switch arrays
… for applications to chemiresistors, which are resistance-based sensors for volatile organic compounds. This material is a polymer composite containing Au-coated magnetic particles organized into electrically conducting pathways by magnetic fields. This improved material overcomes the various …
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Integrated Piezoresistive Sensing for Feedback Control of Compliant MEMS
… flex to perform their functions, their resistance changes. That resistance change can be used to transduce the structures' deflection into an electrical signal. This dissertation addresses three topics associated with integrated piezoresistive sensing: developing an empirical model …
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Effects of organophosphate esters on blood vessels: a physiological, pharmacological, and histological assessment of involvement in organophosphorus-induced delayed neuropathy (OPIDN)
… measured at a constant flow used to indicate changes in vascular resistance. Changes in vascular resistance in response to acetylcholine, phenylephrine, and salbutamol that were different from those in control and PXN-treated hens were noted 1 and 3 days after administration of PSP. These …
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The oat-crown rust pathosystem: an interaction of a plant, a pathogen, and time
… also dependent on time. A pathogen population changes over time, by a process of selection, to defeat the resistances deployed in crop cultivars. The genetic architecture of disease resistance changes as a plant grows from a seedling to an adult plant, matures, and dies. The visual and spectral …
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Low Energy Order-To-Disorder Transition Pathways In Phase-Change Nanowires
… the other hand, it has been recently shown that resistance switching in PCM systems such as superlattices and nanowires can occur at much lower current densities, where the temperature of the material always stays below its melting point. In-situ transmission electron microscopy (TEM) studies on …
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Design and fabrication of a MEMS-array pressure sensor system for passive underwater navigation inspired by the lateral line
… of the diaphragm deflection and strain-gauge resistance changes in response to changes in applied external pressure confirm that the devices can be reliably calibrated for use as pressure sensors to enable passive navigation by AUVs. A set of sensors with millimeter-scale spacing, 2.1 to 2.5 …
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Position Estimation in Switched Reluctance Motor Drives Using the First Switching Harmonics of Phase Voltage and Current
… flux, the effects of eddy current losses and resistance changes due to heating decrease the magnetic field strength and thereby the reduced magnetic field decreases the magnetic flux-linkage of SRM. These losses make a challenge to the measurement of magnetic characteristics of SRM. These …
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