On the design of multiple key hashing files for concurrent orthogonal range retrieval between two disks

This paper concerns the following problem: given a set of multi-attribute records, a fixed number of buckets and a two-disk system, arrange the records into the buckets and then store the buckets between the disks in such a way that, over all possible orthogonal range queries (ORQs), the disk access concurrency is maximized. We shall adopt the multiple key hashing (MKH) method for arranging records into buckets and use the disk modulo (DM) allocation method for storing buckets onto disks. Since the DM allocation method has been shown to be superior to any other allocation methods for allocating an MKH file onto a two-disk system for answering ORQs, the real issue is knowing how to determine an optimal way for organizing the records into buckets based upon the MKH concept.

A performance formula that can be used to evaluate the average response time, over all possible ORQs, of an MKH file in a two-disk system using the DM allocation method is first presented. Based upon this formula, it is shown that our design problem is related to a notoriously difficult problem, namely the Prime Number Problem. Then a performance lower bound and an efficient algorithm for designing optimal MKH files in certain cases are presented. It is pointed out that in some cases the optimal MKH file for ORQs in a two-disk system using the DM allocation method is identical to the optimal MKH file for ORQs in a single-disk system and the optimal average response time in a two-disk system is slightly greater than one half of that in a single-disk system.     

一种实用的数字式亮度调整电路

分析了当今继电保护人机接口亮度调整所用的方式,以及该方式在现场运行所存在的调节麻烦、精度不高、随时间和温度漂移大、调节时需要螺丝刀,自动化程度很低的问题;针对这些问题介绍了一种实用数字式亮度调整电路,阐明了该电路的优点、设计原理、注意事项。     

铁路大功率机车CIR的常见故障分析

介绍了机车综合无线通信设备CIR在铁路和谐号大功率机车上的应用情况,重点分析了CIR常见故障产生的原因及处理方法,并预测了CIR设备在和谐号大功率机车上未来的发展趋势。     

灵宝换流站运行人员控制系统介绍

对西北—华中背靠背直流联网工程的运行人员控制系统设计实施方案做出了较为详尽的介绍。为满足 直流系统正常运行及运行、调度等部门的实际要求,在综合考虑技术成熟及先进性的基础上,该系统集成了充分满 足各方面需求的换流站控制和监视功能,并具有较高的性能指标。     

EMS系统人机会话功能中一体化技术的应用

从系统的角度论述了在电力调度自动化系统MMI模块中图库一体化、显示平台一体化、调度集控一体化等技术的发展和应用。     

多模干涉型集成光学器件研究进展

基于自镜像效应(SIE)的多模干涉(MMI)型集成光学器件是集成光学中具有广泛用途的重要器件。本文详细而系统地综述了近几年来MMI器在国内外的研究进展,特别是其在集成光学中的应用。     

环形谐振腔GaAlAs／GaAs四端口滤波器的仿真与实验研究

基于四端口谐振腔滤波理论,采用时域有限差分法(2D—FDTD)对环行谐振腔的滤波特性进行数值仿真,仿真结果给出多模干涉(MMI)耦合长度与滤波特性的关系．所制作的两种GaAlAs／GaAs平面波导环形谐振腔窄带滤波器的测试结果与仿真结果符合较好．     

Experimental research on an integrated thermooptic switch based on multimode interference couplers

The experimental results of a 2 × 2 integrated thermooptic Mach-Zehnder interferometer (MZI) switch based on multimode interference (MMI) couplers are reported. The insertion loss (IL) is 3.40 dB, the polarization dependent loss is 0.47 dB, the extinction ratio (ER) at bar state and cross state is 32.01 dB and 16.42 dB respectively, the response time is less than 3 ms, and the power consumption is 658 mW. Regarding the asymmetry of extinction ratio at bar state and cross state, theoretical analysis is first presented. The coupling ratio of the two MMI couplers deviates from 50:50 but the deviation is nearly the same, which is decided by good uniformity of semiconductor planar lightwave circuit (PLC) process. This property affects the extinction ratio at bar state and cross state in different mechanisms. Adding a metal electrode on the waveguide affects its effective index and analysis based on experimental results is given. The increment of waveguide effective index is in the order of 2 × 10⁻⁴. Translated from Acta Optica Sinica, 2006, 26(8): 1187–1191 [译自: 光学学报]     

基于MTK平台的手机应用程序开发

随着移动通讯的迅速发展,手机已经成为现代生活中不可缺少的工具.在高速发展的手机市场,MTK以其成本低,开发周期短,功能强大等特点而快速风靡于世.描述了在MTK平台下的手机应用程序开发设计和实现,并且对MTK平台上如何进行软件开发的流程作了阐述,对其软件架构、程序设计、问题解决等工作进行了研究和探讨.     

手机MMI自动化测试系统的关键技术研究

在分析了实现手机人机界面(MMI)软件自动化测试的原理和技术难点的基础上,通过游程长度编码算法对屏幕数据进行压缩和一些数据比较技巧来解决屏幕数据传输与比较问题;通过一系列容错处理来保证ATS系统在无人参与的情况下自动运行;通过对系统软硬件进行抽象和加入TCL脚本解释器来增强系统的可扩展性和可重用性;最后应用这些技术方案实现了一个实际可用的ATS系统;应用结果表明,该系统能大幅提高手机MMI的测试效率。