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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Requirements and limitations of boost-phase Ballistic Missile intercept systems

Uzun, Kubilay 09 1900 (has links)
Approved for public release; distribution is unlimited / The objective of this thesis is to investigate the requirements and limitations of boost phase ballistic missile intercept systems that contain an interceptor and its guidance sensors (both radar and infrared). A three- dimensional computer model is developed for a multi-stage target with a boost phase acceleration profile that depends on total mass, propellant mass and the specific impulse in the gravity field. The radar cross-section and infrared radiation of the target structure is estimated as a function of the flight profile. The interceptor is a multi- stage missile that uses fused target location data provided by two ground-based radar sensors and two low earth orbit infrared sensors. Interceptor requirements and limitations are derived as a function of its initial position from the target launch point and the launch delay. Sensor requirements are also examined as a function of the signal-to- noise ratio during the target flight. Electronic attack considerations within the boost phase are also addressed including the use of decoys and noise jamming techniques. The significance of this investigation is that the system components within a complex boost phase intercept scenario can be quantified and requirements for the sensors can be numerically derived. / Captain, Turkish Air Force
52

Simulation of performance of quantum well infrared photocetectors

Psarakis, Eftychios V. 06 1900 (has links)
In this thesis the performance of a step quantum well infrared photodetector, designed by Kevin Lantz (June 2002) and experimentally studied by Michael Touse (September 2003) and Yeo Hwee Tiong (December 2004), was simulated in Matlab using the transfer matrix method. The results obtained by the Matlab program are compared with the experimental results in a try to make inferences about the optimum way of designing QWIP detectors. Simulation of the above implies numerical solution of the SchroÌ dinger equation, using algorithms and methods, which give accurate results. In our approach, the transfer matrix method is used with exponential and, Airy functions to represent the solutions to SchroÌ dinger equation under zero and nonzero bias, respectively. In the final section of the thesis we examine and simulate in Matlab the application of the extended Kalman filtering (EKF) to an infrared photodetector as a target tracking mechanism to both maneuvering and non-maneuvering targets.
53

Fabrication and Characterization of Photon Radiation Detectors

Mattsson, Claes January 2007 (has links)
<p>This thesis involves a study the fabrication and characterization of photon radiation detectors. The focus has been to develop and improve the performance of optical measurement systems, but also to reduce their cost. The work is based on the study of two types of detectors, the position sensitive detector and the thermal detector.</p><p>Infrared detectors are usually subcategorized into photonic detectors and thermal detectors. In the thermal detectors, heat generated from the incident infrared radiation is converted into an electrical output by some sensitive element. The basic structure of these detectors consists of a temperature sensitive element connected to a heat sink through a thermally isolating structure. Thin membranes of Silicon and Silicon nitride have been commonly used as thermally insulation between the heat sink and the sensitive elements. However, these materials suffer from relatively high thermal conductivity, which lowers the response of the detector. The fabrication of these membranes also requires rather advanced processing techniques and equipment. SU-8 is an epoxy based photoresist, which has low thermal conductivity and requires only standard photolithography. A new application of SU-8 as a self-supported membrane in a thermal detector is presented. This application is demonstrated by the fabrication and characterization of both an infrared sensitive thermopile and a bolometer detector. The bolometer consists of nickel resistances connected in a Wheatstone bridge configuration, whereas the thermopile uses serially interconnected Ti/Ni thermocouple junctions.</p><p>The position sensitive detectors include the lateral effect photodiodes and the quadrant detectors. Typical applications for these detectors are distance measurements and as centering devices. In the quadrant detectors, the active region consists of four pn-junctions separated by a narrow gap. The size of the active region in these detectors depends on the size of the light spot. In outdoor application, this spot size dependence degrades the performance of the four-quadrant detectors. In this thesis, a modified four-quadrant detector having the pn-junctions separated by a larger distance has been fabricated and characterized. By separating the pn-junctions the horizontal electric filed in the active region is removed, making the detector spot size insensitive.</p><p>Linearity of the lateral effect photodiodes depends on the uniformity of the resistive layer in the active region. The introduction of mechanical stress in an LPSD results in a resistance change mainly due to resistivity changes, and this affects the linearity of the detector. Measurements and simulations, where mechanical stress is applied to LPSDs are presented, and support this conclusion.</p>
54

Fabrication and Characterization of Photon Radiation Detectors

Mattsson, Claes January 2007 (has links)
This thesis involves a study the fabrication and characterization of photon radiation detectors. The focus has been to develop and improve the performance of optical measurement systems, but also to reduce their cost. The work is based on the study of two types of detectors, the position sensitive detector and the thermal detector. Infrared detectors are usually subcategorized into photonic detectors and thermal detectors. In the thermal detectors, heat generated from the incident infrared radiation is converted into an electrical output by some sensitive element. The basic structure of these detectors consists of a temperature sensitive element connected to a heat sink through a thermally isolating structure. Thin membranes of Silicon and Silicon nitride have been commonly used as thermally insulation between the heat sink and the sensitive elements. However, these materials suffer from relatively high thermal conductivity, which lowers the response of the detector. The fabrication of these membranes also requires rather advanced processing techniques and equipment. SU-8 is an epoxy based photoresist, which has low thermal conductivity and requires only standard photolithography. A new application of SU-8 as a self-supported membrane in a thermal detector is presented. This application is demonstrated by the fabrication and characterization of both an infrared sensitive thermopile and a bolometer detector. The bolometer consists of nickel resistances connected in a Wheatstone bridge configuration, whereas the thermopile uses serially interconnected Ti/Ni thermocouple junctions. The position sensitive detectors include the lateral effect photodiodes and the quadrant detectors. Typical applications for these detectors are distance measurements and as centering devices. In the quadrant detectors, the active region consists of four pn-junctions separated by a narrow gap. The size of the active region in these detectors depends on the size of the light spot. In outdoor application, this spot size dependence degrades the performance of the four-quadrant detectors. In this thesis, a modified four-quadrant detector having the pn-junctions separated by a larger distance has been fabricated and characterized. By separating the pn-junctions the horizontal electric filed in the active region is removed, making the detector spot size insensitive. Linearity of the lateral effect photodiodes depends on the uniformity of the resistive layer in the active region. The introduction of mechanical stress in an LPSD results in a resistance change mainly due to resistivity changes, and this affects the linearity of the detector. Measurements and simulations, where mechanical stress is applied to LPSDs are presented, and support this conclusion.
55

Titanium dioxide-based carbon monoxide gas sensors : effects of crystallinity and chemistry on sensitivity

Seeley, Zachary Mark, January 2009 (has links) (PDF)
Thesis (Ph. D.)--Washington State University, December 2009. / Title from PDF title page (viewed on Dec. 28, 2009). "Materials Science Program." Includes bibliographical references (p. 109-118).
56

Design, fabrication and characterization of quantum dot infrared photodetectors

Ye, Zhengmao. Campbell, Joe, January 2003 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 2003. / Supervisor: Joe C. Campbell. Vita. Includes bibliographical references. Available also from UMI Company.
57

Charge transport study of InGaAs QWIPs /

Hoang, Vu D. January 2004 (has links) (PDF)
Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, June 2004. / Thesis advisor(s): Nancy M. Haegel, John Powers. Includes bibliographical references (p. 53-54). Also available online.
58

Design, fabrication and characterization of quantum dot infrared photodetectors

Ye, Zhengmao 27 July 2011 (has links)
Not available / text
59

High-speed and high-saturation-current partially depleted absorber photodetecters [i.e. photodetectors

Li, Xiaowei, 1970 May 5- 01 August 2011 (has links)
Not available / text
60

Chemical plume tracking : from virtuality to reality

Kikas, Timo 08 1900 (has links)
No description available.

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