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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.

Design and testing of long-lifetime active sensor arrays for in-core multi-dimensional flux measurements

George, Tyrel Daniel Frank January 1900 (has links)
Master of Science / Department of Mechanical and Nuclear Engineering / Douglas S. McGregor / Fission chambers are a common type of detector used to determine the neutron flux and power of a nuclear reactor. Due to the limited space and high neutron flux in a reactor core, it is difficult to perform real-time flux measurements with present-day in-core instrumentation. Micro-pocket fission detectors, or MPFDs, are relatively small in size and have low neutron sensitivity while retaining a large neutron to gamma ray discrimination ratio, thereby, allowing them to be used as active neutron flux monitors inside a nuclear reactor core. The micro-pocket fission chamber allows for multiple detectors to be inserted into a flux port or other available openings within the nuclear reactor core. Any material used to construct the MPFD must be rugged and capable of sustaining radiation damage for long periods of time. Each calibrated MPFD provides measurements of the flux for a discrete location. The size of these detectors allows for a spatial map of the flux to be developed, enabling real-time analysis of core burnup, power peaking, and rod shadowing. Small diameter thermocouples can be included with the array to also measure the temperature at each location. The following document details the research and development of MPFDs for long term use in nuclear power reactors. Previous MPFD designs were improved, miniaturized, and optimized for long term operations in reactor test ports designed for passive measurements of fluence using iron wires. Detector chambers with dimensions of 0.08 in x 0.06 in x 0.04 in were attached to a common cathode and individual anodes to construct an array of the MPFDs. Each array was tested at the Kansas State University TRIGA Mark II nuclear reactor to demonstrate functionality. The linear response in reactor power was measured. These arrays have also demonstrated reactor power tracking by following reactivity changes in steady state operations and reactor pulsing events. Stability testing showed consistent operation at 100 kW for several hours. The MPFDs have been demonstrated to be a viable technology for in-core measurements.

A VQ Coding Based Method for Object Detection

Lee, Allen 16 July 2002 (has links)


Haddad, George 01 May 2005 (has links)
Aerosol particle detection and determination finds important applications in the commercial, military and aerospace sectors. Monitoring of clean room environments, and spacecraft integration and check out facilities are some of the most important aplications. In the early days test filters were examined with a microscope to determine the number and size of particles that were being removed from air. Today, most of the commercially available clean room airborne particle counters work on a light scattering principle. They are referred to as Optical Particle Counter or OPC. Essentially, they utilize a very bright laser light source to illuminate the particles. The burst of light energy is converted into a pulse of electrical energy. By measuring the height of the signal and counting the number of pulses the sizes and quantities of particles could thus be determined. The microscope and the OPC techniques have their limitations. The microscope technique is a post contamination assessment technique and the OPC is costly, hard to maintain, lack in counting efficiency and is not mobile. This experimental study demonstrates a novel and inexpensive particle detection technique which is based on the acoustic signature of airborne particles as they are accelerated through an acoustic transducer. The transducer consists of an inlet converging nozzle, a capillary tube and an expansion section. If the air is laden with particles, as the flow accelerates through the inlet, the particles cannot follow the large change in velocity due to their inertia. Vortices are generated as air flows over the particles prior to entering the capillary. These vortices are believed to generate sound, which is amplified by the transducer acting as an organ pipe. This sound emission if measured contains frequencies that are harmonics of the natural frequency of the transducer's air column. Results show how the frequency content of the acoustic signature relates to the fundamental frequency of the transducer's air column. The transducer is able to detect micron sized particles ( 5 to 50 micron) and the sound intensity is a function of the flowrate but not of particle size. This study also shows the ability of the transducer to determine particle concentration as low as few parts per liter (ppl) and compare the data with that obtained from a commercially available aerodynamic particle sizer. / M.S.M.E. / Department of Mechanical, Materials and Aerospace Engineering; / Engineering and Computer Science / Mechanical Engineering

Fault Detection Characterization, Design, and Reliability Analysis

Yang, Shuonan Unknown Date
No description available.

Cytokine signalling in acute pancreatitis

Formela, Laura Janina January 2001 (has links)
No description available.

Accurate location of subcrustal earthquakes and geodynamic implications

Schoeffel, Hans-Joachim January 2000 (has links)
No description available.


Choi, Dae H. 16 January 2010 (has links)
Wireless sensor networks (WSNs) have been developed for a variety of appli- cations such as battle�eld surveillance, environment monitoring, health care and so on. For such applications, the design of WSN has been limited by two main resource constraints, power and delay. Therefore, since wireless sensors with a small battery are subject to strict power constraints, the e�cient usage of power is one of the im- portant challenges. As delay-sensitive applications are emerging, they have been in demand for making a quick decision with the enhanced detection accuracy. Under above constraints, we propose a sequential detection scheme and compare it with a Fixed-sample-size (FSS) detection scheme in terms of power and delay. Our main contribution is to analyze the overall system performance of the proposed scheme in the statistical signal processing framework under of power and delay constraints. In this thesis, we evaluate the overall system performance of sequential detection scheme in a serial multi-hop WSN topology. For sequential detection, the sensor nodes continue to relay the observations to the next node until the sequential detector makes a �nal decision based on the observations. On the other hand, the FSS detector waits until all the observations come to the fusion center, and then gives a �nal decision. For a fair comparison of the two schemes with respect to power and delay, the initial step is to �nd the same detection performance region between the two schemes. Detection performance is evaluated with performance measures such as false alarm, miss and prior probability. Simulation results show that each scheme has an advantage and a disadvantage concerning power and delay respectively. That is, sequential detection performs more e�ciently in delay since the number of samples in sequential detection is less on average than in FSS detection to obtain the same detection performance. However, FSS detection with a small number of packet paths consumes less power than sequential detection. Through the analysis of a cost function, which is a linear combination of power and delay, we compare the cost value between the two schemes and �nd less region of the cost value in both schemes. This analysis will provide a good starting point and foundation for designing an e�cient multi-hop WSN with small power and delay constraints.

Signal detection theory a proposal for a nonparametric model /

Turner, Brandon M., January 2009 (has links)
Thesis (M.A.)--Ohio State University, 2009. / Title from first page of PDF file. Includes vita. Includes bibliographical references (p. 74-76).

Some results in memoryless detection theory

Sadowsky, John Scott. January 1984 (has links)
Thesis (Ph. D.)--University of Wisconsin-- Madison, 1984. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Multipath signal detection using the bispectrum

Pike, Cameron M. January 1990 (has links)
Thesis (M.S.)--Ohio University, November, 1990. / Title from PDF t.p.

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