Includes bibliographical references (p. 52-53).

Report (M.S.)--Virginia Polytechnic Institute and State University. M.S. 1992. / Vita. Abstract. Includes bibliographical references (leaf 48). Also available via the Internet.

Thesis (Masters Diploma (Technology))--Cape Technikon, Cape Town,1984 / The excessive usage of peripheral devices such as TTY's, VDU's and printers, have a significant load on the frontend processor of the Alcatel X83 minicomputer. Because of this, the response time of the front-end processor to the peripher~ls is excessive. This can also be attributed to the fact that the peripherals have small buffers or no buffers at all. These peripheral devices also operate at slow speeds. A slow response time from the mini-computer results in decreased productivity. The mini-computer does not provide ports for parallel printers even though there is an abundance of these type of printers. The unavailability of a variety of interfaces on the minicomputer makes the reconfiguration of the peripheral network inflexible. Replacing the existing peripheral equipment in order to overcome the above limitations will be costly. This thesis describes the design, development and implementation of a data buffer and interface converter which would overcome the above mentioned limitations.

This thesis presents two interface circuits for impedimetric chemical sensors: one for passive chemical sensors and the other for ChemFETs. Both interfaces were fabricated in 0.35μm BiCMOS technology and provide the same output data rate of 1Hz. The interface for passive impedimetric sensors is reconfigurable for performing either resistance or capacitance measurements and provides a fully digital output with less than 81.8μW power consumption at VDD = 2.5V. The interface features a 176dB resistance dynamic range (31.6Ω-200MΩ, <±0.8% nonlinearity, and >40dB SNR) realized with only two sub-ranges to minimize calibration efforts and a 102dB capacitance dynamic range (0.8-1000pF, <±0.2% nonlinearity, and >40dB SNR). The ChemFET interface is a highly versatile system that can generate a wide range of bias voltages (VG up to 9.74V and VD up to 16.3V depending on the measurement modes) and perform either constant voltage or constant current mode measurement. At maximum rated output (VG = 9.74V, VD = 16.3V, and IDS = 15μA), the interface consumes only 2.02μW at VDD = 3.3V and provides analog readout noise levels of 0.0476μARMS at 10μA and 0.503mVRMS for IDS and VT, respectively. Besides attempting versatile system architectures, detailed noise and efficiency analysis were performed for the passive sensor interface and the ChemFET interface, respectively. The noise analysis suggests that different types of noise (correlated or uncorrelated) dominate the noise performance in different measurement ranges and, thus, noise suppression techniques, such as chopper stabilization, correlated double sampling (CDS), and oversampling/averaging, are applied to adequate parts of the interface system. The efficiency analysis of the boost capacitor charger in the ChemFET interface concludes that applying a moderate pulsewidth (200-300ns) to drive the boost converter yields the best efficiencies for charging a capacitor. Compared to interfaces described in the literature, the proposed interface for passive sensors achieves better versatility and wide dynamic range with less number of sub-ranges and power consumption. The proposed interface for ChemFETs achieves wider voltage supply range at very low power level. In-house fabricated chemical sensors, including passive chemical sensors and ChemFETs, were interfaced with the developed circuits and gas-phase chemical measurements with the systems were demonstrated. The novel passive chemical sensor tested in this thesis employs a multi-functional design, which can be configured into either a chemoresistor or a chemocapacitor; the tested ChemFET employs a bottom-gate TFT structure to allow the semiconducting film to interact with the analytes.

Includes bibliographical references (p. 44-48).

Thesis (Ph. D.)--Washington State University, May 2009. / Title from PDF title page (viewed on Apr. 2, 2009). "School of Mechanical and Materials Engineering." Includes bibliographical references.

Thesis (M.S. in electrical engineering)--Washington State University, August 2008. / Title from PDF title page (viewed on Mar. 11, 2009). "School of Electrical Engineering and Computer Science." Includes bibliographical references (p. 48-49).

Besides system level analyses, some implementation issues on switching interface circuits are also investigated. These interfaces show a great potential on harvesting efficiency improvement. Based on the experimental observation, it is found that there is a voltage reversion after every inversion in SSHI, which weakens the harvesting performance. This influence is caused by the dielectric loss in piezoelectric material. A revised model as well as detailed analysis are proposed to evaluate the influence of dielectric loss over the harvesting power degradation. / Considering the practical implementation, a modified self-powered switching interface circuit is proposed. It can achieve better isolation among components and involve less dissipative components. Improved analysis on this self-powered switching interface circuit is also provided. It is shown that the higher the excitation level, the more beneficial for replacing the SEH interface with the self-powered switching interface; meanwhile, the closer between the performances of self-powered and ideal (external powered) switching interfaces. / Owing to the great reduction on power consumption of integrated circuits (ICs) and miniaturization during the past decades, the energy harvesting technique has gained much interest recently with the inspiration that more devices in wireless sensor networks as well as mobile electronics could power themselves by scavenging the ambient energy in different forms. Piezoelectric energy harvesting (PEH) is one of the most widely studied techniques to scavenge energy from ambient vibration sources. With the electromechanical nature, a PEH device can be divided into mechanical and electrical parts. The two parts are linked by the piezoelectric transducer. Literatures on PEH are reviewed and discussed. In the research of PEH, generally there are four different research foci on: mechanical part, electrical part, piezoelectric transduction, and system. / This thesis provides new insight into the research of piezoelectric energy harvesting from some systematic viewpoints. The modeling process of a single degree-of-freedom (SDOF) PEH system is firstly discussed. It shows how the model of a PEH device is built from the material level to element level, and then to device level. In the systematic analysis to PEH devices, the energy flow and impedance based analysis are highlighted. A detailed analysis on the energy flow within the PEH system provides good understanding on the system. However, up to now, most of the researches on PEH have been mainly concerned with the absolute amount of energy that can be harvested from vibrating structures; the detailed energy flow within the system as well as its effect on the vibrating structure, were seldom discussed. By studying the energy flow within three applications of standard energy harvesting (SEH), resistive shunt damping (RSD), and synchronized switching harvesting on inductor (SSHI), it can be concluded that, in a PEH system, the two functions of energy harvesting and dissipation are coexistent. Both of them bring out structural damping. New factors are defined to give a more comprehensive evaluation on the energy flow in PEH systems. / To enhance the harvesting power by using the impedance matching is not new; yet, previous literatures on impedance matching for PEH oversimplified the problem. Without clarification on the energy flow in the PEH system, their objectives on power optimization were ambiguous. Some literatures even assumed that the harvesting interfaces, which are nonlinear in nature, can be equalized to linear loads, and the load impedance can be arbitrarily set. With the understanding on energy flow within piezoelectric devices, we clarify the objective of impedance matching, and further demonstrate that the range of equivalent impedance of existing harvesting interfaces is in fact constrained, rather than unlimited. The analyses on system level provide guideline to improve the harvesting performances. Improvements can be made with innovative designs in either mechanical configuration, piezoelectric transducer, or interface circuit. / Liang, Junrui. / Adviser: Wei-Hsin Liao. / Source: Dissertation Abstracts International, Volume: 73-03, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves [145]-155). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Includes bibliographical references (p. 54-56).

Thesis (M.S. in electrical engineering)--Washington State University, December 2009. / Title from PDF title page (viewed on Jan. 15, 2010). "School of Electrical Engineering and Computer Science." Includes bibliographical references (p. 52-53).