197,171 research outputs found
Investigation of the electrical characteristics of GaAsP light-emitting diodes (LED's) under conditions of mechanical stress
No full textThis thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.The main line pursued is the mechanical stressing of light-emitting diodes (LED's) by pressing on the surface with spherically rounded sapphire probes ranging from 100
μm to 500 1m radius of curvature and with forces up to 50 grams weight on the largest probe, care being taken not to exceed the elastic limit of the material, which is estimated to be about 1.4 x 10^9 pascals (14,000 atmospheres) at the central bottom point of the probe. With the diode under forward bias a very wide range of current is covered from 10 mA to about 100 pA in the light-emitting region and from 100 pA to 100 nA in the generation/recombination region - and across the whole range a small decrease in current of about 1 per cent or less is observed. The classical theory of the distribution of stress by a spherical probe has been investigated by a modern computer
technique, and by integration of the stress over the whole of the junction interface it is shown that the decrease in current can be ascribed to the increase in band gap of the
semiconductor that is brought about by the axial component of pressure stress at right angles to the interface. With the larger currents in the light-emitting region a
further decrease in current of the order of 1 per cent or less can be ascribed to heat conduction from the warm surface of the diode to the probe, thereby. lowering the
temperature of the interface. Finally, the electrical characteristics of the diode under reverse bias have been investigated, with incident light playing an important
role; in the absence of light the extremely small currents (10^-12 to 10^-10 amp) are consistent with thermal generation
of carriers similar to the generation/ recombination mechanism for very low currents in the forward direction
Dr. Duane M. Jackson, Morehouse College, July 2011
No full textThis video is a conversation with Dr. Duane M. Jackson. Dr. Jackson talks about his paper, "Recall and the Serial Position Effect: The Role of Primacy and Recency on Accounting Students' Performance." Jackie Daniel, AUC Woodruff Library, is the interviewer
Metric learning on high-dimensional data with optimal transport distances
No full textOptimal transport distances (OT), also known as Kantorovich or Wasserstein distances and its approximate variants such as Sinkhorn Divergences have been widely used in recent years in the field of Machine Learning and its applications. From being used as loss functions in generative model setups such as GANs & unsupervised domain adaptation, to the more recent cluster assignment in self-supervised large state-of-art models such as SWAV, they offer a principled way to compare probability distributions. It is an automatic machinery that takes as an input a ground metric on the data features and lifts this to distances between probabilities on that data space. One of the pitfalls of other often-used methods such as Kullback-Leibler from the family of f-Divergences is the breaking of euclidean metrics in high dimensional spaces, as well as infite solutions when the support of the distributions doesn’t match.
In the first part of the thesis, we provide an introduction to Optimal Transport theory, followed by the relevant literature in metric learning & generative modelling that covers OT, including a few advancements in approximations of OT distances, i.e. Sinkhorn divergences, that make training generative models with the Wasserstein distance, faster and scalable.
Two of the main challenges with using OT distances in practice is the cost of computation when the data lives in high dimension, and the choice of a suitable ground metric. Firstly, we look at the recent work by Paty and Cuturi (2019), which aims specifically at reducing the computational cost by computing OT using low-rank projections of the data, seen as discrete measures. We extend this approach and show that one can approximate OT distances by using more general families of maps provided they are 1-Lipschitz. The best estimate is obtained by maximising OT over the given family. As OT calculations are done after mapping data to a lower dimensional space, our method scales well with the original data dimension and is robust against noise. We demonstrate the idea with neural networks and provide some insights into using these methods for training generative models.
Secondly, we look at learning the ground metric for OT distances in a supervised manner and compare this to traditional metric learning methods such as learning the parameters of Mahalanobis distances on MNIST.
Finally, we consider potential avenues for future research in this area
"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States" By M. Carey.
No full text"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States: containing bried sketches of the moral and political character of those states.
By M. Carey, member of the American philosophical, and of the American Antiquarian Society, and author of The Olive Branch, Cindiciae Hibernicae, essays on banking, on political economy, and on internal improvement.
To which are now added the English editor's comments on the subject; together with Important Advice to Emigrants, and Cautions Against Impositions Practiced in the Outports
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Dr. Glendon Swarthout
No full textHosted by Roger M. Busfield, MSU Assistant Professor of Speech and Theater, Meet the Author is designed to introduce a general audience to a contemporary author and their work through in-depth interviews. This episode features a conversation between Dr. Glendon Swarthout, prolific author and English professor at MSU, and assistant professors Sam S. Baskett and Theodore B. Strandness
Simulation of thermal plant optimization and hydraulic aspects of thermal distribution loops for large campuses
No full textFollowing an introduction, the author describes Texas A&M University and its utilities system. After that, the author presents how to construct simulation models for chilled water and heating hot water distribution systems. The simulation model was used in a $2.3 million Ross Street chilled water pipe replacement project at Texas A&M University. A second project conducted at the University of Texas at San Antonio was used as an example to demonstrate how to identify and design an optimal distribution system by using a simulation model. The author found that the minor losses of these closed loop thermal distribution systems are significantly higher than potable water distribution systems. In the second part of the report, the author presents the latest development of software called the Plant Optimization Program, which can simulate cogeneration plant operation, estimate its operation cost and provide optimized operation suggestions. The author also developed detailed simulation models for a gas turbine and heat recovery steam generator and identified significant potential savings. Finally, the author also used a steam turbine as an example to present a multi-regression method on constructing simulation models by using basic statistics and optimization algorithms. This report presents a survey of the author??s working experience at the Energy Systems Laboratory (ESL) at Texas A&M University during the period of January 2002 through March 2004. The purpose of the above work was to allow the author to become familiar with the practice of engineering. The result is that the author knows how to complete a project from start to finish and understands how both technical and nontechnical aspects of a project need to be considered in order to ensure a quality deliverable and bring a project to successful completion. This report concludes that the objectives of the internship were successfully accomplished and that the requirements for the degree of Degree of Engineering have been satisfied
Intern experience at CH���M Hill, Inc.: an internship report
No full textIncludes author's vita"Submitted to the College of Engineering of Texas A&M University in partial
fulfillment of the requirement for the degree of Doctor of Engineering."Includes bibliographical referencesA review of the author's internship experience with CH���M HILL, Inc.
during the period September 1975 through May 1976 is presented. During this nine month
internship the author worked as an Engineer II in the Industrial Processes discipline of this
large consulting engineering firm... The author's prime responsibility was as one of three
lead design engineers on the design of a large wastewater treatment facility for a pulp mill
in Hoquiam, Washington owned by ITT Rayonier Inc. The work generally consisted of the design
of individual treatment units and associated piping and pumping. The purpose of the project
was to provide wastewater treatment capabilities that would satisfy the effluent limitations
(standards) imposed upon the mill by the State of Washington Department of Ecology and the
U.S. Environmental Protection Agency. The author's assignment also entailed necessary
interaction with the project manager and other CH���M HILL design engineers and support staff
members, the client's representatives, and representatives of two other consulting engineering
firms working on the project. Thus, the internship position at CH���M HILL provided considerable
experience coordinating the author's work with the work of other engineers, guiding the design
and administrative efforts of a support staff, and interacting regularly with the client and
other consulting firms. This broad exposure to a variety of engineering and organizational
problems provided a valuable educational experience
Transition to turbulence in a qblique shock-wave/boundary-layer interaction at M=15
No full textDirect numerical simulations are carried out for different forcing techniques to trigger transition during the interaction between an oblique shock-wave and a laminar boundary-layer at M = 1.5. Three forcing methods are used: a) forcing of oblique unstable modes, whose shape and behaviour are determined by the local linear stability theory, b) broadband free-stream acoustic disturbances, and c) a cold plasma flow control device. While the oblique-mode breakdown is dominant for low-amplitude forcing, long streaky structures drive the transition process in a high-amplitude disturbance environment. LES are also performed on the experimental setup by the Institute of Theoretical and Applied Mechanics (ITAM) from Novosibirsk State University with cold plasma actuation. As well as the disturbance type, the effect of Reynolds number and forcing amplitude will be investigated
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