基于生成语法的英语时态判断

为了帮助中学生掌握英语时态选择题,该文使用了生成语法的基本思想方法,但在其基础上引入了一些新的概念,使其能够在受限领域内可以有效地分析出英语时态选择题的正确答案。文章阐明如何利用现有的生成语法中产生式的思想方法,及新引入的关键字匹配和通配符的概念,使计算机通过规则能够理解英语句子的句型及应该使用的时态。此方法作为选择题判断的一种新尝试。     

The Discrete Logarithm Problem on Elliptic Curves of Trace One

In this short note we describe an elementary technique which leads to a linear algorithm for solving the discrete logarithm problem on elliptic curves of trace one. In practice the method described means that when choosing elliptic curves to use in cryptography one has to eliminate all curves whose group orders are equal to the order of the finite field. Received 9 December 1997 and revised 11 March 1998     

一种锅炉水温智能控制器的设计

介绍了一种水温智能控制器的设计,以单片机为平台,选用高精度传感器Pt100,利用增量式PID算法来实现锅炉水温的智能控制.详细的介绍了单片机系统硬件、传感器电路以及软件的设计实现。     

ZJB(BP)-30A型变频调速高压注浆泵的研制

介绍了ZJB(BP)-30A型变频调速高压注浆泵的设计思路、研制过程以及其主要技术参数和性能特点。     

Symmetric Versus Unsymmetric Platinum(II) Bis(aryleneethynylene)s with Distinct Electronic Structures for Optical Power Limiting/Optical Transparency Trade‐off Optimization

A new series of symmetric and unsymmetric Pt(II) bis(acetylide) complexes of the type D? C≡C? Pt(PBu₃)₂? C≡C? D (D? Pt? D), A? C≡C? Pt(PBu₃)₂? C≡C? A (A? Pt? A) and D? C≡C? Pt(PBu₃)₂? C≡C? A (D? Pt? A) (D, donor groups; A, acceptor groups) are synthesized, and show superior optical power limiting (OPL)/optical transparency trade‐offs. By tailoring the electronic properties of the aryleneethynylene group, distinct electronic structures for these metalated complexes can be obtained, which significantly affect their photophysical behavior and OPL properties for a nanosecond laser pulse at 532 nm. Electronic influence of the ligand type and the molecular symmetry of metal group on the optical transparency/nonlinearity optimization is thoroughly elucidated. Generally, aryleneethynylene ligands with π electron‐accepting nature will effectively enhance the harvesting efficiency of the triplet excited states. The ligand variation to the OPL strength of these Pt(II) compounds follows the order: D? Pt? D > D? Pt? A > A? Pt? A. These results could be attributed to the distinctive excited state character induced by their different electronic structures, on the basis of the data from both photophysical studies and theoretical calculations. All of the complexes show very good optical transparencies in the visible‐light region and exhibit excellent OPL responses with very impressive figure of merit σ_ex/σ_o values (up to 17), which remarkably outweigh those of state‐of‐the‐art reverse saturable absorption dyes such as C₆₀ and metallophthalocyanines with very poor transparencies. Their lower optical‐limiting thresholds (0.05 J cm^?2 at 92% linear transmittance) compared with that of the best materials (ca. 0.07 J cm^?2 for InPc and PbPc dyes) currently in use will render these highly transparent materials promising candidates for practical OPL devices for the protection of human eyes and other delicate electro‐optic sensors.     

四元阵列MEMS矢量水听器的有限元分析

运用ANSYS Workbench12.0有限元软件对一种单片四元阵列微机电系统(MEMS)矢量水听器微结构进行了有限元分析。首先介绍了四元微结构的工作原理,然后推导了四元微结构的数学模型并建立了有限元模型,最后对该微结构进行了静、动态特性分析,得到了该四元微结构的电压灵敏度为0.6 mV/Pa,维间耦合≤1.6%,固有频率为1 982.5 Hz,满足水听器设计指标。     

基于机器视觉的大枣表面缺陷检测

以中国灵武长枣为试验对象,采用Halconl2.0视觉处理软件,通过支持向量机的方法,在HSI颜色空间中提取H分量的均值、方差作为颜色特征值。通过试验选择高斯核函数,当核函数为0.2,正则常数为0.005时达到较好的分级效果,准确率达到94.6%,大大提高了大枣无损在线检测效率,降低了劳动强度和成本。     

结合相位变换形状形成特性的多描述编码

提出一种利用相位变换形状保持特性的错误恢复编码新方法。编码结果的2个描述分别由相位图像和像素交织产生。该方法在有较大失真的情况下,可由相位图和失真幅值合成逼真的原图像：若2个描述都被正确接收,从相位图像和失真较少的幅度可重构一幅高质量的图像;若其中一个描述丢失,甚至在图像传输过程遭到严重破坏时,利用相同方法,能重构一幅可接受图像。实验结果显示,与像素交织和相扰的多描述算法相比,该算法的峰值信噪比（PSNR）可以高出1.5～3 dB。     

超微孔SiO2负载Pt催化剂的合成、表征与催化苯乙炔硅氢加成性能

以超微孔二氧化硅为载体,制备了负载的铂胶体催化剂,用液氮吸附-脱附,FT-IR,ICP,UV-solid等技术对催化剂进行了表征.在微波反应器中将催化剂用于催化苯乙炔与甲基氢二氯硅烷硅氢加成反应,结果显示该催化剂有很高的催化活性和重复实用性.无溶剂、100℃下反应0.5h,甲基氢二氯硅烷的平均转化率可达96.61%,区域选择性β-(E)加成产物大于99.50%.催化剂性能稳定,回收使用5次无明显失活.     

新加坡一体化公交发展模式的经验探讨

对世界上公共交通发展得最好的城市之一——新加坡公交发展模式的详细介绍和总结,重点剖析新加坡的公交体制模式、公交线网模式、公交服务及监管模式、公交补贴及票价模式等四部分核心内容,提出适合中国大城市公共交通发展模式。