Simulation study of peak junction temperature and power limitationof AlGaAs/GaAs HBTs under pulsed and CW operation

The authors have used a 3-D transmission-line matrix (TLM) modeling method to study the junction temperature distribution and power limitation of device geometries with multiple embedded heat sources. Peak values of the junction temperature against the dissipated power density under both pulsed and CW operation are presented for a typical power AlGaAs/GaAs HBT structure. These data should facilitate the rapid determination of junction temperature for a given output power, which is of paramount importance in power device design     

Determination of the liquidus lines and isotherms of the Hg-Zn-Te system by a modified direct observation method

The modified direct observation method is employed for the determination of the liquidus lines in the (Hg_{1_x}Zn_x)_{1_y}Te_y, ternary system. The liquidus temperatures of the ternary samples of various compositions withx from 0.05 to 0.30 andy from 0.5 to 0.9 are measured. The temperature-composition phase diagrams and some liquidus isotherms are established for this system.     

Efficient algorithms for SS/TDMA scheduling

Efficient scheduling algorithms for the slot assignment problem in a satellite-switched time-division multiple-access (SS/TDMA) system are presented. This problem is translated into a modified open-shop scheduling problem, allowing the use of known optimal algorithms. Their complexity is expressed as a function of the following parameters: the number of nonzero entries in the demand matrix, the number of uplinks, and the number of downlinks. According to the values of these parameters, the algorithm with the lowest computational complexity can be adopted. Although the computational complexity of previously published algorithms is drastically reduced, simulation results show that the results are close to previously presented solutions in terms of the assignment duration and the number of switching matrices     

济钢中板厂加快技术创新的对策

本文通过对中板厂近年来技术改造后工艺装置和技术水平的分析，并结合中国加入WTO后对中国钢铁企业面临全球化市场竞争严峻性的认识，提出了中板厂在实现高产生产模式后，应加快技术创新的步伐，尽快完成由高产向优质、多品种、低消耗的高效化生产模式转化的主导思想、措施及建议。     

Continuous Separation of Inclusions from Aluminum Melt Flowing in a Circular Pipe using a High Frequency Magnetic Field

The continuous separation of inclusions from aluminum melt flowing in a circular pipe using a high frequency magneticfield was investigated both theoretically and experimentally The separation efficiency was calculated based on thetrajectory method and compared with experimental results. It is found that the separation efficiency is a functilnondimensional parameters t_i·d_p~2B_e~2/μ_fμ_eα~2 and α/δ.The effective way to improve the separation efficiency is to increasethe effective magnetic flux density and decrease the pipe radius. and the value of α/δ should be kept about 2 in orderto obtain the optimum separation efficiency.     

Eigenvalue-based algorithms for testing positive realness of SISO systems

A computational test for scalar positive real and strictly positive real functions is proposed in this paper. The input for this algorithm is state space representation, not necessarily minimal. It is derived for the discrete time problem, based on numerical stable eigenvalue computations. The test can be used in the continuous counterpart, which is in fact an improvement of an algorithm posed by Bai and Freund. Differences between the discrete and continuous time problems are also pointed out.     

Fuzzy reasoning Petri nets

This paper presents a fuzzy reasoning Petri net (FRPN) model to represent a fuzzy production rule-based system. The issues of how to represent and reason about rules containing negative literals are addressed in the proposed PN model. The execution rules based on the model are defined formally using the operators in max-algebra. Then, a fuzzy reasoning algorithm is proposed to perform fuzzy reasoning automatically. The algorithm is consistent with the matrix equation expression method in the traditional PNs and allows one to exploit the maximum parallel reasoning potential embedded in the model. The legitimacy and feasibility of the proposed approach are proved and validated through a turbine fault diagnosis expert system.     

安钢宽板坯连铸机达产实践

分析了安钢宽板坯连铸机在热试车期间出现的生产问题,总结出制约生产主要因素,制定针对性措施,使该连铸机在较短时间内实现达产创效.