Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering, 1953. / Includes bibliographical references. / by Rudolph John Cypser. / Sc.D.

Recent years have seen a push to provide a fast, sensitive, and quantitative diagnostic tool for biomedical applications. A search for new methods that can perform label-free and bond-specific determination of tissue and disease types with high spatial resolution is much desired. To address these needs, we have developed a mid-infrared photothermal system for sensitive and non-destructive characterization of samples. Our system utilizes a mid-infrared pump with a near-infrared probe for label-free spectroscopy and high spatial resolution imaging. In particular, this research focuses on optimization of the photothermal system, exploration of novel nonlinear photothermal phenomena, and development of a sub-diffraction limited mid-infrared imaging system. Photothermal spectroscopy is a pump-probe technique that utilizes a thermal lens effect in the sample for contrast. With the use of a high brightness mid-infrared pump laser, we extend photothermal spectroscopy into the mid-infrared regime for sensitive detection with high signal contrast. Targeting vibrational modes intrinsic to the sample allows for label-free characterization. Use of a fiber laser probe provides improved spatial resolution and takes advantage of the well-developed detector technology at near-infrared wavelengths. The research presented will be divided into three parts: optimization of the photothermal system, investigation of novel nonlinear photothermal phenomena, and photothermal spectroscopy and imaging for biomedical applications. Optimization of fiber laser design and experimental setup results in >100x increase in signal strength and over an order of magnitude improvement in signal contrast. With an optimized system, linear and nonlinear mid-infrared photothermal spectroscopy of a liquid crystal sample is demonstrated. For the first time, multiple bifurcations are reported in the nonlinear regime, shedding insight on the photothermal laser-matter interaction across phase transitions of a liquid crystal sample. Using a raster-scanning approach, sub-diffraction limited mid-infrared imaging is demonstrated. With this technique, various tissue types within the brain can be distinguished from one another, including differentiation between healthy and tumor tissue. Hyperspectral imaging of biological tissues demonstrates the potential of this technique to combine both spectral and spatial information for sample characterization. We present a photothermal system with the potential to meet the demands in drug and food safety, environmental monitoring, biomedicine, and security. / 2018-11-02T00:00:00Z

<p> A method for sizing battery energy storage (BES) systems for use in mitigating voltage flicker caused by solar intermittency in photovoltaic generation was developed. The method creates a &ldquo;design day&rdquo; from existing solar data and designs the power and energy requirements for a BES system that can help a photovoltaic facility mitigate flicker caused by solar activity associated with the design day. An economic analysis of lead-acid and lithium-ion options for the BES was also developed. The method was then applied to a proposed photovoltaic project in the Midwestern United States.</p><p>

A satellite's absolute attitude and angular rate are both important measurements for satellite missions that require navigation. Typically, these measurements have been made by separate sensors, with star cameras being used to determine a satellite's absolute attitude, and gyroscopes being used as the primary rate sensors. Recently, there have been multiple efforts to measure both of these quantities using only the star camera, however the work primarily involves solutions where the optical sensor and the unit that processes the images are separate integrated circuits. Operation in this modality requires the use of chip to chip communication in order to estimate angular rate from star tracker images, which can lead to an increase in system power, a degradation in performance, and increased latency. The goal of this thesis is to consolidate the sensing and processing into a single integrated circuit. The design and evaluation of a digital processing unit that estimates angular rate and facilitates the realization of image sensor and processor integration is presented. The processing unit is implemented in UMC's 130 nm process, has an area of 10 mm × 200 μm, and consumes 8.253 mW of power.

Thesis (Sc.D.) Massachusetts Institute of Technology. Dept. of Electrical Engineering, 1955. / Bibliography: leaves 148-150. / by Paul Eugene Stoft. / Sc.D.

Thesis (M.S.) Massachusetts Institute of Technology. Dept. of Electrical Engineering, 1953. / Bibliography: leaf 36. / by Ronald Leslie Thompson. / M.S.

Thesis (M.S.) Massachusetts Institute of Technology. Dept. of Electrical Engineering, 1952. / Bibliography: leaves 63-64. / by Hideo Mori. / M.S.

<p> Source localization using TDOA measurements has been an important research topic mainly because of its wide applications in practical localization systems. The TDOA localization accuracy is known to be very sensitive to the sensor position errors and even a small amount of sensor position errors can cause significant performance loss. This thesis considers the use of calibration emitters to improve the source location estimate from TDOAs when the sensor positions are subject to random errors. The principle behind is that with calibration emitters, extra TDOA measurements that contain information on the true sensor positions can be obtained and if properly exploited, they are able to mitigate the effect of sensor position errors and improve the source localization accuracy. This thesis investigates, in four different localization scenarios (scenarios (i)- (iv)), the effect of calibration TDOA measurements on the source localization accuracy and how to efficiently explore them in the localization algorithm design to achieve the optimum performance. </p><p> We consider in scenario (i) the TDOA localization of a source in the presence of sensor position errors when a calibration emitter at perfectly known position is available. The CRLB of the source location estimate for this case is derived and it indicates that the utilization of calibration TDOAs can lead to great improvement in localization accuracy over the case without a calibration emitter. The performance of the differential calibration (DC) method used in GPS to mitigate the effect of satellite position uncertainty and other errors using a calibration emitter is analyzed theoretically. It is shown that in general, the DC method cannot attain the CRLB accuracy. We then develop a novel algorithm that explores the TDOA measurements from both the calibration emitter and the unknown source to estimate the source location. The newly proposed solution is in closed-form and more importantly, we prove analytically that unlike the DC method, it can reach the CRLB accuracy under two mild conditions.</p><p> Scenario (ii) is practically more realistic than scenario (i) in the sense that besides the known sensor positions, the calibration positions also have random errors and the number of calibration emitters can be greater than one. We establish the CRLB of the source location estimate for this case and quantify the performance degradation due to the calibration position errors. The sensitivity of the source location estimate to the calibration position errors is investigated and the result indicates that the source localization accuracy can be severely degraded if the calibration position errors are simply ignored. Based on this observation, a closed-form TDOA localization algorithm that takes both the calibration position errors and the sensor position errors into account is developed. The proposed solution explores all the calibration TDOAs to improve performance and it is shown analytically to reach the CRLB accuracy under mild conditions.</p><p> In scenario (iii), multiple sources at unknown locations need to be localized from TDOA measurements when the sensor positions are not known accurately. This problem includes the scenario where a single source is located with calibration emitters at completely unknown positions as a special case. The multiple sources are assumed to be disjoint and for each source, a separate set of TDOA measurements is obtained. Recognizing that in literatures, only iterative methods are available for the multiple source localization problem, we propose a closed-form solution that does not require iterations and is computationally more attractive. The new concept of hypothesized source positions is introduced in the algorithm development. Through theoretical performance analysis, we show that the proposed solution is able to attain the CRLB localization accuracy under small noise conditions. The developed algorithm can also provide improved sensor positions as a byproduct. (Abstract shortened by ProQuest.)</p><p>

Massachusetts Institute of Technology. Dept. of Electrical Engineering. Thesis. 1970. M.S. / MICROFICHE COPY ALSO AVAILABLE IN BARKER ENGINEERING LIBRARY. / Bibliography: p. 46. / M.S.

Thesis (M.S.) Massachusetts Institute of Technology. Dept. of Electrical Engineering, 1950. / Bibliography: leaf 51. / by John Albert Gautraud. / M.S.