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排序方式: 共有9848条查询结果,搜索用时 62 毫秒
991.
连关培 《昆明理工大学学报(自然科学版)》1995,(1)
研究因同步带传动的出现和应用而对带传动中心距计算提出的新要求、新问题。对于ISO推荐的精确计算式,导出了已很接近精确解的迭代初值的估算式,籍此明显地提高了迭代计算的效率。对于目前流行的常用式,经过改造,得到了它新的表达式。藉此解决了迄今ISO精确式和常用式在形式上不统一的问题,并且给出了概括它们的统一的普遍式。 相似文献
992.
字幕机系统是当今电视节目制作中心必不可少的设备之一。本文基于ADDA公司的Aver-PRO字幕图形卡作为硬件平台,面向我国广大的中、小电视台和电教中心,设计开发了一套具有较高性能价格比的中英文字幕机系统-VNC7800。该系统具有性能稳定、功能多、操作简便、价格适中等优点。 相似文献
993.
Shinji Shinnaka 《Electrical Engineering in Japan》2002,141(3):58-69
This paper proposes a new position‐sensorless position control method for high‐speed spindle drive systems. Mechanical vulnerability of position sensors such as an encoder mounted on a spindle motor is becoming a serious problem as required speed increases. For high speeds above 1500 rad/s, sensorless drive is preferred. It is possible for current technologies to control spindle motor in speed control mode without the sensor, but not in position control mode without the sensor. In the example of high‐speed spindle systems of automatic machine tools, implements must be automatically attached to and removed from the spindle at standstill. Automation necessitates position control, for which current technologies require a sensor. The proposed method makes it possible to realize pure sensorless high‐speed spindle systems performing in both speed and a position control modes. The method can attain a position control performance with quick settling from speed control and a repetitive positioning precision of 0.006 rad, 0.4°, which is comparable to that achieved by current sensor‐based methods. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 141(3): 58–69, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10059 相似文献
994.
In this paper, a low-order parametric force model to represent the electromagnetic force on an eccentric rotor of a salient-pole
synchronous machine was developed and verified. The force model with parameters estimated from the results of impulse method
showed excellent performance. The proposed model allowed quick and accurate calculation of the electromagnetic force at the
desired whirling frequency values and provided an opportunity to effectively combine the electromagnetic and mechanical analyses
of electrical machines. Besides, results presented in this paper also verified the suitability of computationally efficient
impulse method for the analysis of a synchronous machine. 相似文献
995.
Automatic code synthesis from dataflow program graphs is a promising high-level design methodology for rapid prototyping of multimedia embedded systems. Memory efficient code synthesis from dataflow models has been an active research subject to reduce the gap in terms of memory requirements between the synthesized code and the hand-optimized code. However, existent dataflow models have inherent difficulty of efficiently handling data structures. In this paper, we propose a new dataflow extension called fractional rate dataflow (FRDF) in which fractional number of samples can be produced and consumed. In the proposed FRDF model, a constituent data type is considered as a fraction of the composite data type. Existent integer rate dataflow models can be easily extended to incorporate the fractional rates without loosing analytical properties. In this paper, the SDF model is extended to include FRDF, which can reduce the buffer memory requirements significantly, up to 70%, for some multimedia applications. Extended SDF model with fractional rate has been implemented in our system design environment called PeaCE(Ptolemy extension as Codesign Environment). 相似文献
996.
997.
Tadashi Hirayama Jun Oyama Tsuyoshi Higuchi Takashi Abe 《Electrical Engineering in Japan》2008,165(1):82-90
This paper presents the principle and basic characteristics of a novel linear synchronous motor based on “half‐wave rectified self excitation principle.” The field winding is short circuited through a diode and the armature winding consists of conventional three‐phase windings. If the amplitude of the balance three‐phase currents is modulated by an alternating wave with bias frequency, the produced magnetomotive force pulsates at the bias frequency and moves at the synchronous velocity. This pulsating magnetomotive force induces the electromotive force with a bias frequency in the field winding. The field excitation is obtained by rectifying the electromotive force with the diode in the field winding. In this paper, the authors design and build an experimental machine and confirm its basic characteristics. They also deduce the performance equations and investigate the thrust ripple reduction. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 165(1): 82–90, 2008; Published online in Wiley InterScience ( www. interscience.wiley.com ). DOI 10.1002/eej.20684 相似文献
998.
灯泡贯流式水轮发电机通风系统的有限元计算 总被引:1,自引:0,他引:1
采用有限元方法对5500kW/6471kVA灯泡贯流式水轮发电机通风系统进行了求解,得到了通风系统的压降分布和速度分布.水轮发电机的结构对通风系统的压降影响较大,通过计算发现压降较大的部位并对其进行了修改.设计好的机组目前已投入使用,运行情况良好. 相似文献
999.
介绍一种为大电流开关点火的精密长延迟纳秒高压脉冲源的研制。采取低压固体电路与大小氢闸管电路的合理配置,较好地解决了精密长延迟和高压脉冲输出时低延迟时间晃动的难点。该源具有延迟时间晃动小和可调的精密长时间延迟、上升时间小和幅度大的脉冲输出、抗强脉冲干扰等特性。 相似文献
1000.
Yuji Mishima Koichi Nara Taiji Satoh Takamitsu Ito Hirotoshi Kaneda 《Electrical Engineering in Japan》2005,152(2):18-25
This paper proposes a loss minimum reconfiguration method by tabu search for an open‐loop radial distribution system with distributed generators. The problem is to find the optimal normal open sectionalizing switch positions which minimize the total distribution line losses subjected to the line/transformer capacity constraints and voltage constraint. Generally, the problem is mathematically formulated as a complex combinatorial optimization problem or mixed integer programming problem, and is solved by using mathematical programming method, heuristic algorithm, intelligent method, and so on. However, a satisfactory algorithm for power companies has not yet been attained in both computational burden and solution accuracy. Thus, in this paper, the authors propose a method to solve the above problem by using tabu search (TS). Reverse power flow caused by distributed generators can be included in the solution algorithm. TS is one of the meta‐heuristic algorithms, and sometimes has been evaluated to be better than genetic algorithm (GA) or simulated annealing (SA) from viewpoints of both computational speed and solution accuracy. In order to evaluate the validity and efficiency of the algorithm, several numerical examples are shown in this paper. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 152(2): 18–25, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20086 相似文献