400 mm厚大面积地坪一次整浇施工工艺

大面积厚地坪采用软缝,可一次浇筑不留施工缝;使用内燃式振动梁找平混凝土,通过埋设振动梁轨道控制地坪标高表面平整度;接槎处设凹槽控制平整度和表面质量;采用严格控制坍落度和二次振捣工艺,控制和减少沉陷量;采用机械抹光工艺,提高抹面速度及质量;及时切割诱导缝,减少了裂缝发生的可能性。     

三峡工程深水截流探讨

结合三峡工程深水截流问题,探讨了抛石截流戗堤塌滑现象分类,抛石稳定的演变过程,抛石不稳定结构的突变理论应用,截流抛石浸水湿化速率与微结构不稳定性关系,以及浸水湿化速率的模型与原型相似性模拟等问题。由于这些问题国内外尚未见到成果发表,故本文的一些观点也许对江河截流感兴趣的人员有参考价值。     

DF 系统振动深孔钻的设计与应用

针对深孔加工的特点,设计了ＤＦ系统振动深孔钻,分析了振动钻削过程中喷吸效应的各项影响因素,提出了消除影响的具体措施。介绍了ＤＦ系统振动钻削切屑处理的有效方法。     

振动平板夯的动力学性能

针对现有振动平板夯运动模型不符合实际工况,受力状态过于简化,提出了一种精细运动模型。分析了振动平板夯的运动过程,导出了平板夯的受力公式。借助有限元分析方法,利用计算机可视化程序,模拟振动平板夯的实际工作情况,获得夯板在各种载荷下的应力和变形值,为振动平板夯的设计、生产及工程应用提供了理论依据。     

Fundamental characteristics of semiconductor ring laser gyroscopes

Semiconductor ring lasers have many capabilities of realizing new functional devices. In this paper, we propose a novel optical inertial rotation sensor using a semiconductor ring laser. If a semiconductor ring laser operates as an optical inertial rotation sensor, a very small and simple optical gyroscope can be realized. To our knowledge this is the first demonstration of a semiconductor ring laser gyroscope (S‐RLG). Experimental results are as follows. (1) The Sagnac frequency shift can be detected as a beat note by the terminal voltage change of the semiconductor ring laser without branching the circulating optical power. Therefore, the S‐RLG system can be constructed very simply as compared with already proposed optical gyroscopes. (2) The detected beat frequency between two counterpropagating lasers in the S‐RLG is directly proportional to the applied rotation rate. (3) Furthermore, we present data demonstrating the injection locking phenomenon around low rotation rate. These results verify that the proposed S‐RLG operates as an optical inertial rotation sensor based on the Sagnac effect. © 2000 Scripta Technica, Electr Eng Jpn, 132(4): 73–78, 2000     

A method of damping transient rush voltage fluctuation of power systems due to a wind driven generator via nonlinear state feedback control

Squirrel-cage induction generators are widely used as generators for windmill power systems, because they are inexpensive, have high durability, and are capable of operating asynchronously with power systems. However, induction generators suffer the drawback that they cause transient rush currents that are several times larger than the rated value when connected to power systems. Also since wind energy is influenced by geographic and weather conditions, start/stop operations occur frequently for windmill power systems. Therefore, connecting induction generators to power systems causes undesirable voltage fluctuations in power systems, which is the major obstacle against the practical use of windmill generator systems. This motivates the study of transient rush current/voltage attenuation in windmill generator systems. In this paper, a nonlinear state-feedback controller for windmill power systems is proposed. The proposed controller globally asymptotically stabilizes the plant and effectively attenuates the transient current/voltage of these systems. Computer simulations using parameters for an actual windmill generator system also gave good results. © 1998 Scripta Technica, Electr Eng Jpn, 124(1):17–23, 1998     

考虑阻抗双解现象的可控串补模式切换控制方法

可控串联补偿(thyristor controlled series capacitor,TCSC)的模式切换对电力系统的稳定控制具有重要意义。TCSC阻抗双解现象的存在对其模式切换提出了更高的要求,单一改变触发角的方法无法实现模式切换。在考虑阻抗双解现象影响的基础上,提出了一套相应的TCSC模式切换控制方法。通过强制晶闸管支路电流与线路电流同步,实现由容性区到Bypass模式的切换;在由容性区到感性微调模式切换的过程中提出了晶闸管条件触发的方法,即当线路电流和电容电压满足同向条件时晶闸管才触发导通。同时为及时向切换控制提供线路电流同步信号,提出了一种预测电流过零的新方法。数字仿真及动模实验结果表明,提出的切换方法能使切换过程平稳迅速,且动态特性良好。     

A study of three‐dimensional observation of prebreakdown phenomena in dielectric liquids

This paper presents a new method which visualizes the high‐speed three‐dimensional images of prebreakdown streamers in dielectric liquids. A new optical system, having two crossed light axes to observe the needle tip from different directions, was designed. The shadowgraphic images from these two directions were combined through a beam splitter and focused on the photo‐cathode of an image converter camera. The photograph taken by this high‐speed shadowgraph system was reconstructed to three‐dimensional images using an image scanner and a computer. Using this system, the growth and decay processes of the streamer in cyclohexane were investigated. © 1999 Scripta Technica, Electr Eng Jpn, 128(4): 9–15, 1999     

商品天然气烃露点测定方法及其溯源性

在输配系统特定工况下,高压输送的商品天然气有可能因降压而产生反凝析现象并在气相中形成重烃液滴。因此,应规定烃露点指标以保障生产系统的安全平稳运行。由于天然气组成极其复杂,其相态特性完全不同于其他单一组分和/或简单的多元混合物。因此,准确测定商品天然气的烃露点相当困难。扼要介绍了工业上常用的3种烃露点测定方法及其溯源途径。手动或自动式冷镜仪法均为物性测定方法,其测定结果不具备溯源性,无法评定测量结果的不确定度。PHLC法的技术特点为基于同一压力下冷镜法露点仪测得的烃露点值与被测气体中潜在烃含量的相关性而建立了冷镜法的溯源程序。目前,先进的自动冷镜仪测定烃露点的准确度已经达到±0.5℃。用状态方程计算烃露点的方法虽然有严密的化学热力学基础,但由于受取样代表性、色谱分析结果准确性及数据处理方式等诸多因素的影响,应用并不广泛。     

风电装备行星轮系过盈接触特性分析

风力发电对于保障我国能源安全具有重大意义,但我国风电装备发展中还存在巨大技术瓶颈,如何进一步提高装备可靠性及寿命是亟需解决问题。以行星轮系过盈配合面接触特性与微动磨损关系为切入点,针对NGW型行星轮受力分析,计算获取过盈配合接触分析的载荷边界条件;通过对比不同过盈量在无外载工况下的配合面压力值,理论计算与仿真分析结果的平均误差约为5.74%,验证了仿真的可信度;通过对比不同过盈量在无外载下的变形量,行星轮内孔面与轴承外圈变形占比分别为89.5%和10.5%,定量描述了行星轮相较于轴承的变形程度,更易损伤;稳态载荷工况下,通过对比不同配合公差P6和R6下的最大微动滑移量可知,P6公差带下最大微动量随载荷变化幅度较大,因此风电行星轮配合公差应选R6更合适;非稳态载荷工况下,通过数值积分计算获取不同过盈量下的配合面打滑极限载荷,该极限值作为评定实际服役工况下出现剧烈"打滑现象"的准则,因此设计时应考虑该极限工况。