Bandwidth-Constrained Allocation in Grid Computing

Grid computing systems pool together the resources of many workstations to create a virtual computing reservoir. Users can “draw” resources from this reservoir using a pay-as-you-go model, commonly used for utilities (electricity and water). We model such a system as a capacitated graph, and study a basic allocation problem: given a set of jobs, each demanding computing and bandwidth resources and yielding a profit, determine which feasible subset of jobs yields the maximum total profit. A preliminary version of this paper was presented at the 2003 Workshop on Algorithms and Data Structures, Ottawa. The work of Anshul Kothari and Subhash Suri was supported in part by National Science Foundation grants IIS-0121562 and CCR-9901958.     

Wind Power Estimation Using Artificial Neural Network

Wind energy conversion systems appear as an attractive alternative for electricity generation. To maximize the use of wind generated electricity when connected to the electric grid, it is important to estimate and predict power produced by wind farms. The power generated by electric wind turbines changes rapidly because of the continuous fluctuation of wind speed and wind direction. Wind power can be affected by many other factors such as terrain, air density, vertical wind profile, time of a day, and seasons of a year and usually fluctuates rapidly, imposing considerable difficulties on the management of combined electric power systems. It is important for the power industry to have the capability to perform this prediction for diagnostic purposes—lower than expected wind power may be an early indicator of a need for maintenance. A multilayer perceptron (MLP) network can be used to estimate wind turbine power generation. It is usually important to train a neural network with multiple influence factors and big training data set. The extended Kalman filter training algorithm has to be parallelized so that it can provide fast training even for large training data sets. The MLP network can then be trained with the consideration of various possible factors, which can cause influence on turbine power production.     

A review of three-phase improved power quality AC-DC converters

Three-phase AC-DC converters have been developed to a matured level with improved power quality in terms of power-factor correction, reduced total harmonic distortion at input AC mains, and regulated DC output in buck, boost, buck-boost, multilevel, and multipulse modes with unidirectional and bidirectional power flow. This paper presents an exhaustive review of three-phase improved power quality AC-DC converters (IPQCs) configurations, control strategies, selection of components, comparative factors, recent trends, their suitability, and selection for specific applications. It is aimed at presenting a state of the art on the IPQC technology to researchers, designers, and application engineers dealing with three-phase AC-DC converters. A classified list of around 450 research articles on IPQCs is also appended for a quick reference.     

Non-specific seminal tract infection and male infertility: a bacteriological study

70 infertile males with epididymal tenderness, pus cells in the semen, and/or history of urinary tract infection were studied by semen culture examination. Significant growth of Streptococcus fecalis, Escherichia coli, coagulase positive Staphylococci, Proteus valgaris, Pseudomonas pyocyanea, and beta hemolytic Strepticocci was found in 42.9% of the cases. Most of the tested strains were sensitive to ampicillin, cotrimoxazole, nitrofurantoin, erythromycin, and chloramphenicol. In a control group of 20 healthy fertile males, only an insignificnat growth of Staphylococcus albus and Streptococcus facalis was found in 65% of the samples. Nonspecific seminal tract infection can be an important cause of male infertility. These infections may affect fertility in several ways: by damaging sperm, hampering their motility, altering the chemical composition of the seminal fluid, or by producing an inflammatory structure in the tract. Seminal infection could also be the cause of the chronicity of urinary tract infection by acting as the reservoir of infection.     

GaAs MESFET and related processes

Since inception of GaAs MESFET in 1971, growth and processing technology of GaAs has matured to the extent that the analogue as well as digital IC production is persued at the industrial level. The ever increasing demand for higher frequency of operation, low noise figure and higher gain has led to newer device structures such as HEMT and HJBT based on GaAs and related compounds. Furthermore there exists exciting and proven capabilities in GaAs and related compounds to generate, detect and convert light into electrical signals. This has opened up vast field of opto-electronic devices and their integration with MESFET and other conventional devices. Basic building block of all these developmental activities still remains the GaAs MESFET, which have also been extensively used as low noise amplifiers, mixers, oscillators and high power amplifiers in descrete form. This paper reviews the design aspects, fabrication technology, d.c. and microwave characterization for both low noise and high power MESFET. Various technological advancements like via-hole for source grounding, air-bridge technology for low parasitic interconnects and polymide passivation, which have helped in further improvement in terms of higher frequency of operation, low noise and high power output are reviewed. Finally some representative results on the devices fabricated at CEERI are also presented.     

Purification and properties of aortic cholesteryl ester hydrolase

The enzyme(s) present in acetonedried powder of rat and rabbit aortas, which catalyzes the synthesis and hydrolysis of cholesteryl ester, was purified partially by acid precipitation, acetone fractionation, 0-(diethylaminoethyl) cellulose chromatography, and Sephadex G-100 filtration. The synthetic activity was purified by 120-fold (rat) and 140-fold (rabbit). Purification of hydrolytic activity was 90-fold (rat) and 103-fold (rabbit). Cholesteryl ester hydrolase activity was separated from nonspecific, esterase by column chromatography. Both synthetic and the hydrolytic activities are apprently the functions of one enzyme. The mol wt of the enzyme was estimated to be 140,000 dalton as determined by Sephadex G-200 gel filtration. The extracts of the acetone-dired powders of aortas of both species contained an inhibitor of synthetic activity. The inhibitor was nondialyzable and was precipitated at pH 5.7 Both activities were found to be fairly nonspecific with regard to sterol and fatty acids. With oleic acid, the relative rates of sterol ester synthesis were: cholesterol, 100; cholestanol, 94; desmosterol, 35; corprostanol, 24; ergosterol, 20; and β-sitosterol, 19. Epicholesterol was not esterified. Oleic acid was most active in cholesteryl ester synthesis, the relative rates being: oleic>linoleic>arachidonic>palmitic>stearic>butyric. The rate of hydrolysis was maximum with cholesteryl linoleate followed by oleate, linolenate, palmitate, stearate and laurate in decreasing order.     

The development of risk assessment models for carpal tunnel syndrome: a case-referent study

The present study developed risk assessment models for carpal tunnel syndrome (CTS) which can provide information of the likelihood of developing CTS for an individual having certain personal characteristics and occupational risks. A case-referent study was conducted consisting of two case groups and one referent group: (1) 22 work-related CTS patients (W-CTS), (2) 25 non-work related CTS patients (NW-CTS), and (3) 50 healthy workers (HEALTHY) having had no CTS history. The classification of CTS patients into one of the case groups was determined according to the type of insurance covering their medical costs. Personal characteristics, psychosocial stresses at work, and physical work conditions were surveyed by using a questionnaire tailor-designed to CTS (reliability of each scale > or = 0.7). By contrasting the risk information of each case group to that of the referent group, three logistic regression models were developed: W-CTS/HEALTHY, NW-CTS/HEALTHY, and C-CTS/HEALTHY (C-CTS, the combined group of W-CTS and NW-CTS). ROC analysis indicated that the models have satisfactory discriminability (d' = 1.91 to 2.51) and high classification accuracy (overall accuracy = 83-89%). Both W-CTS/HEALTHY and C-CTS/HEALTHY include personal and physical factors, while NW-CTS/HEALTHY involves only personal factors. This suggests that the injury causation of NW-CTS patients should be attributable mainly to their 'high' personal susceptibility to the disorder rather than exposure to adverse work conditions, while that of W-CTS patients be attributable to improper work conditions and CTS-prone personal characteristics in combination.     

Some theorems on generalized thermoelastic diffusion

The objective of the present work is to establish a convolutional type (Gurtin in Arch. Rat. Mech. Anal. 16:34?C50, 1964) variational theorem and a reciprocity theorem for the linear theory of generalized thermoelastic diffusion for homogeneous and isotropic elastic solids.