Microprocessor based simulation and digital logic model of gate turn-off thyristor

A digital logic model of a gate turn-off thyristor is developed considering the turn-on and turn-off mechanisms of the device. A commonly used R-C-D snubber circuit is also included in the proposed model. Relations between different delay times, e.g. storage time, Tall time, turn-off time and tail time, become apparent from the model. The model is simulated with the help of a microprocessor to establish the validity of the proposal.     

Evaluation of electron temperature in transverse and axial magnetic fields in an arc plasma by diffusion voltage measurement

The diffusion voltage in a mercury arc plasma has been measured for arc currents from 2.5 A to 5 A in transverse and axial magnetic fields from zero to 1.1 kG. Assuming the radial distribution of charged particles proposed by Ghosal et al, (1978) and utilizing the method of Sen et al. (1983), the ratio of electron temperatures with and without a magnetic field has been evaluated. It becomes a maximum in an axial field and then decreases, whereas it shows a minimum in a transverse field and then increases. An expression for the ratio of the electron temperature with and without a field has been deduced that explains these results. Quantitative agreement between experiment and theory is fairly satisfactory.     

A NOVEL QUICK-CLOSING PROBE FOR MEASURING LOCAL PARTICULATE PHASE DENSITY IN GAS-PARTICLE SUSPENSIONS

ABSTRACT

An innovative quick-closing probe system was designed, built, and tested for measuring the local particulate phase density of gas-particle suspensions. Experiments with glass beads and powder coals were conducted in a horizontal channel with an aspect ratio of 11 to 1, and also in a 0·25 m I.D. bench-scale vortex chamber. Results of particle density distributions in these two systems indicated the ability of the probe to perform in highly turbulent, swirling, dilute and intermediate phase gas-particle suspension flows. The probe was connected with a microcomputer-assisted particle weighing system for data collection and reduction. Comparison of measured data by this probe with calculated results was assessed. Since this probe requires no calibration curve nor empirical equation, it serves as a primary standard for particle density measurements. The design features, working principle, component characteristics, overall performance, and test results are discussed in this paper.     

Reactions of Aqueous Chlorine and Chlorine Dioxide with Tryptophan, N-Methyltryptophan, and 3-Indolelactic Acid: Kinetic and Mutagenicity Studies

Reactions of tryptophan, N-methyltryptophan and 3-indolelactic acid with aqueous chlorine or chlorine dioxide (ClO₂) in 0.1M potassium phosphate buffer, pH 6.0, were investigated to determine any structural relationships with regards to kinetics and mutagenicity. The reaction with ClO₂ followed pseudo-first order kinetics, with the half-life of the respective compounds being 36, 22, and 8 milliseconds. The formation of a dark precipitate in the reaction of tryptophan with HOCl precluded any kinetic comparison. The reaction products of tryptophan with hypochlorous acid (HOCl) or ClO₂ were mutagenic to Salmonella typhimurium TA98 and TA100; while those of N-methyltryptophan with HOCl and ClO₂ were more mutagenic toward TA98. Higher recoveries of the reaction products were achieved by passing the acidified (pH 2.5) mixture through an XAD-8/XAD-2 resin column.     

Individual learning of coordination knowledge

Abstract. Social agents, both human and computational, inhabiting a world containing multiple active agents, need to coordinate their activities. This is because agents share resources, and without proper coordination or ‘rules of the road’, everybody will be interfering with the plans of others. As such, we need coordination schemes that allow agents to effectively achieve local goals without adversely affecting the problem-solving capabilities of other agents. Researchers in the field of Distributed Artificial Intelligence (DAI) have developed a variety of coordination schemes under different assumptions about agent capabilities and relationships. Whereas some of these researchers have been motivated by human cognitive biases, others have approached it as an engineering problem of designing the most effective coordination architecture or protocol. We evaluate individual and concurrent learning by multiple, autonomous agents as a means for acquiring coordination knowledge. We show that a uniform reinforcement learning algorithm suffices as a coordination mechanism in both cooperative and adversarial situations. Using a number of multi-agent learning scenarios with both tight and loose coupling between agents and with immediate as well as delayed feedback, we demonstrate that agents can consistently develop effective policies to coordinate their actions without explicit information sharing. We demonstrate the viabilityof using both the Q-learning algorithm and genetic algorithm based classifier systems with different pay-off schemes, namely the bucket brigade algorithm (BBA) and the profit sharing plan (PSP), for developing agent coordination on two different multi-agent domains. In addition, we show that a semi-random scheme for action selection is preferable to the more traditional fitness proportionate selection scheme used in classifier systems.     

New results in stability of a class of hereditary linear systems

Some basic connections between bounded-input, bounded-output stability and exponential asymptotic stability are presented for a class of linear time-varying hereditary systems. For that class of systems, controllability and observability are closely related to that of an equivalent linear system. This eases the analytical treatment of such properties which are then used to derive the stability results. The requirement of boundedness of inputs and outputs in the BIBO definition is modified by requesting that their ‘energy content’ over a fixed-length interval should be bounded independently of the position of the interval. For the class of hereditary linear systems studied, it is found that EAS and BIBO stability are equivalent under uniform complete controllability and observability.     

蒙古语语言-文字的自动化处理

本文首先叙述了蒙文电子化的意义以及蒙文电子化数据的现状。然后重点讨论了在不同地区和国家使用的蒙文书面语以及口语的不同和蒙文在计算机处理时所面临的问题。最后,介绍了我们在日本建设的针对蒙古语语言信息处理的两种语言资源:蒙古语多方言口语语料库和蒙文多文种-多语言并行语法标注电子词典,后者得到了2005年中日蒙韩国际合作课题“蒙文自然语言处理技术的研究”的资助。     

A STATE-MODEL REPRESENTATION OF THE PARAMETRIC TRANSFORMER

ABSTRACT

A state model of a new passive device capable of transferring electrical energy from one circuit to another through parametric excitation is developed. The state equations of the parametric transformer under various load conditions are then solved numerically to obtain the output voltage, the currents in the input and output circuits and the variable inductance responsible for parametric oscillations. The computed values are compared with those obtained from measurements made on a small experimental unit.     

一种分布式无线感应网定位算法研究

作为一种全新的信息获取和处理技术,无线传感器网络可以在广泛的应用领域内实现复杂的大规模监测和追踪任务,而网络自身定位是大多数应用的基础,本文提出一个分布式定位算法,可以在仅有一小部锚节点的无线感应网中动态定位全体节点,同时提出一些算法改进,可以有效的减少定位误差.