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Load Changes (load + change)
Selected AbstractsRelationship between Contact Voltage Drop and Frictional Coefficient under High-current Sliding ContactIEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING, Issue 4 2010Takahiro Ueno Member Abstract Large DC motors are used in various industrial applications. These motors repeatedly generate arcs between the brush and commutator, because the load change is intense and the current value is also large. In particular, for the case in which the current is concentrated on a part of the brush, brush burnout may occur as a result of overcurrent. Therefore, excellent brushes to withstand arc generation and with good electrical properties are required. In the present paper, we discuss the relation between contact voltage drop and frictional wear for electrical sliding contacts when high currents flow to the brush. Specifically, we investigate the means by which to prevent brush burnout when high-current flows to the brush. Copyright © 2010 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source] Application of a self-tuning to automatic generation control in power system including smes unitsEUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 2 2002A. Demirören In this study, a self-tuning control scheme is proposed and applied to automatic generation control (AGC) in power system with superconducting magnetic energy storage (SMES). The system is assumed consisting of two areas. The proposed self-tuning control scheme is used to implement the automatic generation control adding to conventional control configuration. The performance of the system for load changes in the areas in the interconnected power system is studied. A comprehensive performance evaluation of the system is presented. The computer simulation of the interconnected power system with two areas shows that the proposed self-tuning control scheme is very effective in damp out of oscillations caused by load disturbances. [source] Antiviral activity of low-dose alovudine in antiretroviral-experienced patients: results from a 4-week randomized, double-blind, placebo-controlled dose-ranging trial,HIV MEDICINE, Issue 3 2007J Ghosn Background Alovudine inhibits replication of highly nucleoside reverse transcriptase inhibitor (NRTI)-resistant HIV strains in vitro. However, dose-dependent safety concerns resulted in its initial development being halted. Recently, a 4-week course of alovudine 7.5 mg/day added to a stavudine-free failing regimen yielded a significant decrease in viral load by ,1.88 log10 HIV-1 RNA copies/mL. The magnitude of the reduction in viral load suggested that lower doses might still be effective while offering adequate safety during long-term use. Objective To determine whether lower dosages of alovudine still provide significant antiviral activity in patients with broad NRTI resistance. Methods A randomized, double-blind, placebo-controlled trial investigating three doses of alovudine (0.5, 1 and 2 mg) or placebo added for 4 weeks to a failing regimen in patients with evidence of NRTI-resistant HIV strains [,2 thymidine-associated mutations (TAMs)]. The primary endpoint was the mean viral load reduction between baseline and week 4. Results Seventy-two patients were enrolled in the study: 21, 13, 18 and 20 in the placebo and 0.5, 1 and 2 mg arms, respectively. Baseline median CD4 count and viral load were 298 cells/,L (range 44,692 cells/,L) and 3.9 log10 copies/mL (range 2.5,5.2 log10 copies/mL), respectively. Baseline viral isolates harboured a median of four TAMs. Alovudine was added to a median four-drug failing regimen. At week 4, compared with placebo, mean viral load changes were ,0.42 log10 [95% confidence interval (CI) ,0.67 to ,0.18] and ,0.30 log10 (,0.55 to ,0.06) in the 2 and 1 mg arms, respectively. There was no significant change in CD4 cell count. Alovudine was well tolerated. Conclusion: A 4-week course of alovudine 2 mg/day provided a modest but significant viral load reduction in patients harbouring viruses with a median of four TAMs. [source] Transient simulation of a catalytic converter for a dual fuel engineTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2000Benlin Liu Abstract An experimental and modelling study was performed for a catalytic converter attached to a natural gas/diesel dual fuel engine. The catalytic converter was a ceramic monolith honeycomb substrate coated with a washcoat of catalyst. A multiple segmented design of converter was used. This paper describes the application of a one-dimensional finite element model for the transient and steady state operation of this converter. The model is a single channel model. The laminar flow was approximated using a dispersed plug flow model. The chemical kinetics were simulated using LHHW type expressions. Comparison of simulated results are made with experimental results for heating and cooling cycles that resulted from speed and load changes on the engine. These comparisons showed a maximum difference between experimental and predicted emission levels of about 10%. On a mené une étude expérimentale et réalisé la modération d'un convertisseur catalytique relié è un moteur è combustible double gaz naturel/diesel. Le convertisseur catalytique est un substrat de monolithes céramique en nid d'abeille enduit d'une couche de catalyseur. Une conception segmentée multiple a étée utilisée pour le convertisseur. On décrit dans cet article l'application d'un modèle d'éléments finis unidimensionnel pour un fonctionnement en régime transitoire et permanent du convertisseur. Ce modèle est un modèle à canal unique. L'écoulement laminaire a été approximé à l'aide d'un modèle à écoulement piston dispersé. La cinétique chimique a été simulée au moyen d'expressions de type LHHW. On effectue une comparaison entre les résultats simulés et les résultats expérimentaux pour les cycles de chauffe et de refroidissement qui résultent des changements de vitesse et de charge sur le moteur. Ces comparaisons montrent une différence maximum entre les taux d'émission expérimentaux et prédits d'environ 10%. [source] Robust Neural Network Controller Design For A Biaxial Servo SystemASIAN JOURNAL OF CONTROL, Issue 4 2007Chih-Hsien Yu ABSTRACT A robust control method for synchronizing a biaxial servo system motion is proposed in this paper. A new neural network based cross-coupled control and neural network techniques are used together to cancel out the skew error. In the proposed control scheme, the conventional fixed gain PID cross-coupled controller (PIDCCC) is replaced with the neural network cross-coupled controller (NNCCC) to maintain biaxial servo system synchronization motion. In addition, neural network PID position velocity and velocity controllers provide the necessary control actions to maintain synchronization while following a variable command trajectory. This scheme provides strong robustness with respect to uncertain dynamics and nonlinearities. The simulation results reveal that the proposed control structure adapts to a wide range of operating conditions and provides promising results under parameter variations and load changes. [source] An Investigation into the Transient Behavior of a Microreactor System for Reforming of Diesel Fuel in the kW RangeCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 11 2009M. O'Connell Abstract A diesel reformer based on microreaction technology was developed for application in an auxiliary power unit (APU) system. The transient characteristics of this reactor for reforming of diesel fuel are reported. Diesel steam reforming was performed at various S/C ratios with load changes ranging from 30 % LL to 80 % LL, i.e., a 1.5 kW to a 4 kW electrical equivalent. The reactor itself was based on an integrated reformer/burner heat exchange reactor concept. The reforming was performed at temperatures above 750,°C and at various S/C ratios, down to a minimum of 3.17. Variation of experimental parameters, such as O/C and S/C ratios, are critical for optimum and efficient operation of the reformer. [source] | |||||||||||||