汉语自动标引加权方法试验研究

本文介绍了几种自动标引加权方法,以及把这几种方法应用于汉语文献自动标引试验的情况,给出了试验的有关数据、基于数据的分析和推出的结论,并对汉语科技文献自动标引中的若干问题进行了探讨。     

A 155 Mbps laser diode driver with automatic power and extinction ratio control

An integrated laser diode driver(LDD) driving an edge-emitting laser diode was designed and fabricated by 0.35 μm BiCMOS technology. This paper proposes a scheme which combines the automatic power control loop and temperature com-pensation for modulation current in order to maintain constant extinction ratio and average optical power. To implement tem-perature compensation for modulation current,a novel circuit which generates a PTAT current by using the injecting base current of a bipolar transistor in saturation region,and alternates the amplifier feedback loop(closed or not) to control the state of the current path is presented. Simulation results showed that programmed by choice of external resistors,the IC can provide modu-lation current from 5 mA to 85 mA with temperature compensation adjustments and independent bias current from 4 mA to 100 mA. Optical test results showed that clear eye-diagrams can be obtained at 155 Mbps,with the output optical power being nearly constant,and the variation of extinction ratio being lower than 0.7 dB.     

PLC对继电器控制线路的改造

PLC是英文“ProgrammableLosicController”的缩写词,中译名为“可编程控制器”。可编程控制器是集计算机技术、自动控制技术、通信技术为一体的新型自动控制装置。其性能的优越,已被广泛地应用于工业控制的各个领域。PLC的优点：1）可靠性高,抗干扰能力强。2）适应性强,应用灵活。3）编程方便,易于使用。4）功能性强,扩展能力强。     

中考物理高分之路系列讲座

命题方向：对于光学部分内容，历年来的考查比例都在7％左右．相对来说，新大纲对这部分的要求有所降低，中考命题对这一部分的难度系数也作了相应调整．对考生来说，这部分的考分相应的容易拿一些．但如何做到不失分，得高分，还需要同学们正视．     

A prototype of workflow management system for construction design projects

1 Introduction 1 In recent years there is a growing understanding of the importance of effective design management to facilitate a coordinated building design within budget, and to ensure the smooth operation of a project [1]. Therefore, it becomes a certain tendency that management of construction design project should combine with information technology (IT) to approach information share and process integration. Since the application of computer-aided design technology (CAD) in China at la…     

Automatic generation method of geological cross-sections in dredging engineering based on 3D solid NURBS models

An automatic generation method of geological cross-sections in dredging engineering based on 3D geological solid models is presented.The 3D geological models are built applying the non-uniform rational B-splines(NURBS) technique,and a 2D profile can be calculated and generated automatically through Boolean operation to meet the demands of dredging projects.Moreover,an automatic marking method for geological attributes is put forward based on database technology,and the geological attributes include the profile name,scale,horizontal and vertical relative coordinates,geological lithology,and 2D standard lithology legend.At the same time,the automatic marking method can also provide an interactive mode for geological engineers to edit and modify the profile in the modeling system.Practical engineering applications show that the automatic generation method is a simple,flexible,fast and precise visual graphics rendering process that can create 2D standard profiles automatically and efficiently.This method also provides a convenient support tool for geological engineering digital analysis.     

本刊启事

为进一步提高办刊质量。本刊自2012年5月起,将正式启用"中国知网学术不端文献检测系统"与"万方数据论文相似性检测系统"。检测系统可有效检测来稿是否存在抄袭、伪造、篡改、一稿多投等多种学术不端行为,并自动生成检测报告。凡有不端学术行为的稿件,编辑部将不予采用。     

程序化自动选择预测模型的一种思路

在预测活动中合理选择预测的模型，既是预测成功的关键，也是预测过程中最感困难的一步。对于企业经营管理活动迫切需要的预测技术，难以广泛普及的因素之一就是预测模型能否科学、合理的选择。利用计算机软件程序化的自动选择预测的模型，进而做到科学的智能化预测，是实现这一目标的一个突破点。本文是在这个方面的一个尝试和努力。     

巷道交岔点防电机车碰头设施的实践与应用

随着矿井的发展,科技的进步,井下电机车使用频率的提高,运送人员与物料的增加,其运输中潜在的隐患也就逐渐显露出来,本文主要针对矿井运输中在巷道交岔点这一环节的隐患点进行现状分析,根据分析结果,制定了相应的措施,在巷道转弯处安装平面反光板和声光报警提示;在交叉点的三个方向,敷设弧形反光板、声光报警指示和传感器,充分利用了声学传播原理及光学原理来杜绝事故的发生。经过实践与应用,完全可以推广应用。