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 20 for “"Lock-In Amplifier"”.
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High vacuum system and instrumentation for measuring the derivative of the current-voltage characteristic of a Langmuir probe
… construction of a high vacuum station and the instrumentation and testing of two methods for obtaining the first derivative of the current-voltage characteristic of a Langmuir Probe, which is needed to determine the electron speed distribution in rare gases. The theory behind using a lock-in …
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Signal Processing Techniques Applied to Biomedical Diagnostics
An effective way to combat cancer and infectious disease in resource-poor settings is to implement rapid and accurate diagnostic tests that can be administered at the point of care (POC). Developing such miniaturized, portable, and low-cost systems requires innovative approaches in both assay and …
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Neutron dosimetry with a water calorimeter
In certain situations neutron radiotherapy has potential advantages over conventional X-ray therapy. It has yet to be conclusively proven that neutron therapy is more efficacious than X-ray therapy, and in many institutions worldwide neutron therapy is currently being evaluated. It is important …
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A Doppler Radar Lock-in Demodulation Algorithm for Machine Vibration Sensing
Data-driven predictive maintenance of modern machinery has the potential to increase equipment lifespan and decrease manufacturing costs. Among various condition monitoring techniques, vibration analysis can effectively diagnose potential problems in machines. Doppler radar can be used as a sensor …
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A study of the polarimetric characteristics of planar chiral mesoscopic structures
… chiral materials can rotate the direction of incident polarized light. This work focuses on a new way of investigating the polarized response of chiral metamaterial structures and nanoparticles. In the theoretical part of this work, fundamental concepts related to chirality are defined. …
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Electrical characterization of high temperature superconductors as a function of temperature
… (BSCCO- 2223/Ag) tapes at temperatures ranging from 77 K to 110 K were measured using a typical four-terminal technique for two different BSCCO-2223/Ag tapes manufactured by Vacuumschmelze (VAC). The critical currents for the two VAC samples were measured as a function of magnetic field …
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Specific loss power optimization in metal ferrite nanocrystals for radiofrequency stimulation of neurons
… serve as the basic unit of computation within the nervous system. As the nervous system is involved with the encoding, transmission, processing, and decoding of information at every level, characterization of the nervous system is of the utmost interest to neuroscience. However, techniques …
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Bridging the Modeling-Sampling Gap for Mid-Infrared Reflectance Spectroscopy of Small Particles, Films, and Fibers
<p>The concentration dependency of the mid-infrared (MIR) absorbance of bacterial spores was determined. Linear relationships (R<sup>2</sup> ≥ 0.99) were observed between the concentrations of spores and the baseline corrected peak absorbance for the amide absorbance regions, at coverages of …
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Design of a hermetically sealed MEMS resonator with electrostatic actuation and capacitive third harmonic sensing
… with low noise. Electrostatic actuation and sensing are both performed using only one pair of electrodes. The motion of the cantilever changes the capacitance of the actuation electrodes at a frequency three times that of the actuation signal. This method allows the desired motion to be picked …
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Microrheology and microstructure of poly(vinyl alcohol)-based physical gels
… and microstructure of physically cross-linked poly(vinyl alcohol) (PVA) gels using atomic force microscopy, dynamic light scattering and particle tracking. We compare the microscopic rheological properties with the bulk properties measured using conventional shear rheometry, and correlate …
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On the Dynamics of Single-Electron Tunneling in Semiconductor Quantum Dots under Microwave Radiation
Efforts are made in this thesis to reveal the dynamics of single-electron tunneling and to realize quantum bits (qubits) in semiconductor quantum dots. At low temperatures, confined single quantum dots and double quantum dots are realized in the twodimensional electron gas (2DEG) of AlGaAs/GaAs …
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DEGENERATE SECOND ORDER NONLINEAR OPTICAL SPECTROSCOPY OF CHIRAL WEYL SEMIMETALS
This thesis focuses on the development of nonlinear optical techniques and the measurement of topological properties of the Weyl semimetals. The first portion of this thesis describes technical developments of the nonlinear optical spectroscopic probes rotational anisotropy second harmonic …
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System Design And Optimization Of Optical Coherence Tomography
Optical coherence imaging, including tomography (OCT) and microscopy (OCM), has been a growing research field in biomedical optical imaging in the last decade. In this imaging modality, a broadband light source, thus of short temporal coherence length, is used to perform imaging via interferometry. …
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THz Radiation Detection Based on CMOS Technology
… band of the electromagnetic spectrum, also defined as sub-millimeter waves, covers the frequency range from 300 GHz to 10 THz. There are several unique characteristics of the radiation in this frequency range such as the non-ionizing nature, since the associated power is low and therefore it is …
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Wavelength tuneable frequency domain photon migration spectrometer for tissue-like media
Frequency domain spectrometers use intensity modulated light to quantitatively interrogate turbid media. The modulation frequencies employed are in the radiofrequency range. Intensity modulated light launched into a turbid medium generates photon density fluctuations with wave like character that …
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Near infrared tunable diode laser spectroscopy for aero engine related applications
… is a widely used technique for recovering quantitative gas information in a range of industrial applications. Established methods often use readily available, robust and low cost optoelectronic hardware in the near-infrared, with output wavelengths that coincide with the absorption …
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Wireless Telemetry System for Implantable Sensors
Advanced testing of medical treatments involves experimentation on small laboratory animals, such as genetically modified mice. These subjects are used to help researchers develop medication and cures for humans. To understand the effects of the treatments, innovative telemetry systems are …
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Surface glassy dynamics and single-molecule absorption of quantum dots detected by scanning tunneling microscopy
Using optically assisted scanning tunneling microscopy (STM), I investigated surface glassy dynamics, absorption spectroscopy and intermolecular energy transfer between single quantum dots (QDs) and carbon nanotubes (CNTs). Glass is an exotic state of matter which is not in equilibrium, but can be …
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Single molecule optical absorption at room temperature detected by scanning tunneling microscopy
The high spatial resolution of the scanning tunneling microscope makes it a powerful tool to investigate single molecules deposited on a variety of conductive or semi-conductive surfaces. By adding laser absorption, we are able to simultaneously examine single molecules with high spatial and high …
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Advances in tunable diode laser spectroscopy for aero engine research
… for the measurement of gas species and offers in-situ operation, accuracy and faster response time compared to other optical and non-optical gas sensing techniques.The work in this thesis focusses on the measurement of CO2 in the harsh environment of a gas turbine engine (GTE). The work is part …