44 research outputs found
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Folder 3: Model engine data sheets and operating instructions, C - D, 1946, 1950, 1960
No full textOperating instructions and parts list for Cameron Aircraft engines. Document from The Wesley Pettinger Engine Model Collection
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Intelligent laser scanning for computer aided manufacture.
No full textReverse engineering requires the acquisition of large amounts of data describing the surface of an object, sufficient to replicate that object accurately using appropriate fabrication techniques. This is important within a wide range of commercial and scientific fields where CAD models may be unavailable for parts that must be duplicated or modified, or where a physical model is used as a prototype. The three-dimensional digitisation of objects is an essential first step in reverse engineering. Optical triangulation laser sensors are one of the most popular and common non-contact methods used in the data acquisition process today. They provide the means for high resolution scanning of complex objects. Multiple scans of the object are usually required to capture the full 3D profile of the object. A number of factors, including scan resolution, system optics and the precision of the mechanical parts comprising the system may affect the accuracy of the process. A single perspective optical triangulation sensor provides an inexpensive method for the acquisition of 3D range image data
Microelectromechanical system-based precision operational amplifier
No full textThesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.Includes bibliographical references (p. 123).This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Two main difficulties for amplifiers that attempt to make precision DC measurements are the inherent low-frequency noise of the amplifier and the leakage current of the amplifier input stage. This thesis presents a novel fully integrated operational amplifier design that addresses both measurement limitations by using a fully differential mechanical transductor input stage, fabricated using SOI-MEMS technology. The input stage of the amplifier is a MEMS structure that provides a variable capacitance to transduce a low-frequency input voltage into a high-frequency AC current. This up-modulation of the input signal is exploited to reduce offsets and low-frequency noise, and the dielectric isolation of the MEMS structure provides high input impedance and low leakage currents. To function, the MEMS-based amplifier includes two co-dependent feedback loops. The 'drive loop' utilizes closed-loop control to vibrate the MEMS structure at its mechanical resonant frequency to produce a modulating capacitance. The 'sense loop' senses the up-modulated signal from the MEMS structure, and provides gain and demodulation to this signal. Global feedback around the sense loop allows for accurate measurement of the input voltage.by Song-Hee Cindy Paik.M.Eng
Hot-thermistor spirometry for the artificial ventilation of infants
No full textBibliography: leaves 230-245.This thesis describes equipment and techniques which were developed for use in monitoring mechanical aspects of artificial ventilation and optimising ventilation procedures. A strong emphasis is placed on the clinical applicability of the techniques and clinical applications are discussed. A new temperature-compensated hot-thermistor anemometer/spirometer was developed because the wide variety of spirometers described previously for-measuring respiratory volumes •and volume flow rates were unsatisfactory for routine use in monitoring infant ventilation. The principles of hot-thermistor spirometry were investigated both theoretically and experimental.ly to develop new temperature-compensation techniques and to predict the effect of gas composition changes on spirometer celebration. New electronic circuits were developed which greatly simplify the construction of temperature-compensated hot- thermistor anemometers and extend the dynamic range off low rates that can be measured
Asymptotic Bayesian Decision Feedback Equalizer Using a Set of Hyperplanes
No full textWe present a signal space partitioning technique for realizing the optimal Bayesian decision feedback equalizer (DFE). It is known that, when the signal to noise ratio (SNR) tends to infinity, the decision boundary of the Bayesian DFE is asymptotically piecewise linear and consists of several hyperplanes. The proposed technique determines these hyperplanes explicitly and uses them to partition the observation signal space. The resulting equalizer is made up of a set of parallel linear discriminant functions and a Boolean mapper. Unlike the existing signal space partitioning technique of Kim and Moon, which involves complex combinatorial search and optimization in design, our design procedure is simple and straightforward, and guarantees to achieve the asymptotic Bayesian DFE
The investigation and design of a piezoelectric active vibration control system for vertical machining centres
No full textNature inspired computational intelligence for financial contagion modelling
No full textThis thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Financial contagion refers to a scenario in which small shocks, which initially affect only a few financial institutions or a particular region of the economy, spread to the rest of the financial sector and other countries whose economies were previously healthy. This resembles the “transmission” of a medical disease. Financial contagion happens both at domestic level and international level. At domestic level, usually the failure of a domestic bank or financial intermediary triggers transmission by defaulting on inter-bank liabilities, selling assets in a fire sale, and undermining confidence in similar banks. An example of this phenomenon is the failure of Lehman Brothers and the subsequent turmoil in the US financial markets. International financial contagion happens in both advanced economies and developing economies, and is the transmission of financial crises across financial markets. Within the current globalise financial system, with large volumes of cash flow and cross-regional operations of large banks and hedge funds, financial contagion usually happens simultaneously among both domestic institutions and across countries. There is no conclusive definition of financial contagion, most research papers study contagion by analyzing the change in the variance-covariance matrix during the period of market turmoil. King and Wadhwani (1990) first test the correlations between the US, UK and Japan, during the US stock market crash of 1987. Boyer (1997) finds significant increases in correlation during financial crises, and reinforces a definition of financial contagion as a correlation changing during the crash period. Forbes and Rigobon (2002) give a definition of financial contagion. In their work, the term interdependence is used as the alternative to contagion. They claim that for the period they study, there is no contagion but only interdependence. Interdependence leads to common price movements during periods both of stability and turmoil. In the past two decades, many studies (e.g. Kaminsky et at., 1998; Kaminsky 1999) have developed early warning systems focused on the origins of financial crises rather than on financial contagion. Further authors (e.g. Forbes and Rigobon, 2002; Caporale et al, 2005), on the other hand, have focused on studying contagion or interdependence. In this thesis, an overall mechanism is proposed that simulates characteristics of propagating crisis through contagion. Within that scope, a new co-evolutionary market model is developed, where some of the technical traders change their behaviour during crisis to transform into herd traders making their decisions based on market sentiment rather than underlying strategies or factors. The thesis focuses on the transformation of market interdependence into contagion and on the contagion effects. The author first build a multi-national platform to allow different type of players to trade implementing their own rules and considering information from the domestic and a foreign market. Traders’ strategies and the performance of the simulated domestic market are trained using historical prices on both markets, and optimizing artificial market’s parameters through immune - particle swarm optimization techniques (I-PSO). The author also introduces a mechanism contributing to the transformation of technical into herd traders. A generalized auto-regressive conditional heteroscedasticity - copula (GARCH-copula) is further applied to calculate the tail dependence between the affected market and the origin of the crisis, and that parameter is used in the fitness function for selecting the best solutions within the evolving population of possible model parameters, and therefore in the optimization criteria for contagion simulation. The overall model is also applied in predictive mode, where the author optimize in the pre-crisis period using data from the domestic market and the crisis-origin foreign market, and predict in the crisis period using data from the foreign market and predicting the affected domestic market
Adaptive Minimum-BER Linear Multiuser Detection for DS-CDMA Signals in Multipath Channels
No full textThe problem of constructing adaptive minimum bit error rate (MBER) linear multiuser detectors is considered for direct-sequence code division multiple access (DS-CDMA) signals transmitted through multipath channels. Based on the approach of kernel density estimation for approximating the bit error rate (BER) from training data, a least mean squares (LMS) style stochastic gradient adaptive algorithm is developed for training linear multiuser detectors. Computer simulation is used to study the convergence speed and steady-state BER misadjustment of this adaptive MBER linear multiuser detector, and the results show that it outperforms an existing LMS-style adaptive MBER algorithm first presented at Globecom'98 by Yeh, Lopes and Barry
Adaptive minimum symbol-error-rate decision feedback equalization for multilevel pulse-amplitude modulation
No full textThe design of decision feedback equalizers (DFEs) is typically based on the minimum mean square error (MMSE) principle, as this leads to effective adaptive implementation in the form of the least mean square algorithm. It is well-known, however, that in certain situations the MMSE solution can be distinctly inferior to the optimal minimum symbol error rate (MSER) solution. We consider the MSER design for multi-level pulse-amplitude modulation. Block-data adaptive implementation of the theoretical MSER DFE solution is developed based on the Parzen window estimate of probability density function. Furthermore, a sample-by-sample adaptive MSER algorithm, called the least symbol error rate (LSER), is derived for adaptive equalization application. The proposed LSER algorithm has a complexity that increases linearly with the equalizer length. Computer simulation is employed to evaluate the proposed alternative MSER design for equalization application with multi-level signalling schemes
Alan F. Clark
No full textALAN F. CLARK
Inducted: 2011
Citation:
For research and leadership excellence in cryogenic properties of materials, superconductivity, and electrical and magnetic standards
Tenure: 1964-2004
Birth: 1936, Milwaukee, Wisconsin
Education:
University of Wisconsin, BS (Physics), 1958
University of Wisconsin, MS (Nuclear Engineering), 1959
University of Michigan, PhD (Nuclear Science), 1964
Positions held:
National Research Council Postdoctoral Associate, NBS (Boulder), 1964-1966
Physicist, Cryogenics Division, Institute for Basic Standards (Boulder), 1966-1977
Leader, Thermophysical Properties of Solids Group, Thermophysical Properties Division, NML (Boulder), 1978-1980
Leader, Superconductor & Magnetic Measurement Group, Electromagnetic Technology Div., NEL (Boulder), 1981-1987
Liaison Scientist, Office of Naval Research, London, UK, (1988-1989)
Leader, Fundamental Electrical Measurements Group, Electricity Division, EEEL (Gaithersburg), 1989-1998
Deputy Chief, Optoelectronics Division, EEEL (Boulder), 1998-2000
Chief, Magnetic Technology Division, EEEL (Boulder), 2001-2003
Chief, Materials Reliability Division, MSEL (Boulder), 2004
Honors:
US Department of Commerce Silver Medal (1987)
Fellow, American Physical Society (1988)
Fellow, Institute of Electrical and Electronics Engineers (1995)
Chairman and President of Board of Directors, Applied Superconductivity Conference
Memberships:
IEEE Transactions on Applied Superconductivity, Editor-in-Chief (1994–1997)
Cryogenics, Americas Editor (1982–1994), Advisory Editor (1977–1981)
Superconductivity, Advisory Editor (1987–1998)
Advances in Cryogenic Engineering—Materials, Plenum, Co-Editor, (1975–1988)
International Cryogenic Monographs, Plenum, Co-Editor (1978–2005)
Materials at Low Temperatures, American Society for Metals, Co-Editor and author (1983)
Founded and chaired: International Cryogenic Materials Conference, International Critical Currents Conference, APS Instrument and Measurement Science Topical Group, Joseph F. Keithley Award Committee, IEEE Committee on Superconductivity, and ASTM B01.08 Committee on Superconductors
Publications:
More than 150 publications and a patent including:
Clark, A.F., Zimmerman, N.M., Williams, E.R., Amar, A., et. al., “Application of Single Electron Tunneling: Precision Capacitance Ratio Measurements,” Appl. Phys. Lett. 66, 2588 (1995)
Early, E.A., Clark, A.F., and Char, K., “Half-Integral Constant Voltage Steps in High-Tc Grain Boundary Junctions,” Appl. Phys. Lett. 62, 3357 (1993)
Moreland, J., Clark, A.F., Goodrich, L.F., Ku, H.C., and Shelton, R.N., “Tunneling Spectroscopy of a La-Sr-Cu-O Break Junction: Evidence for Strong Coupling Superconductivity,” Phys. Rev. B 35, 8711 (1987)
Ekin, J.W., Fickett, F.R., and Clark, A.F., “Effect of Stress on the Critical Current of NbTi Multifilamentary Composite Wire,” Adv. Cryo. Eng. 22, 449 (1977)
Clark, A.F., Childs, G.E., and Wallace, G.H., “Electrical Resistivity of Some Engineering Alloys at Low Temperatures,” Cryogenics 10, 295 (1970)
Clark, A.F., “Low Temperature Thermal Expansion of Some Metallic Alloys,” Cryogenics 8, 282 (1968
