Fault Waveform Regenerator and Its Digital Closed-Loop Modification Technique

In order to provide a novel and more effective alternative to the commonly used relay protection testing device that outputs only the sinusoidal testing signals, the concept of fault waveform regenerator is proposed in this paper, together with its hardware structure and software flow chart. Fault waveform regenerator mainly depends on its power amplifiers (PAs) to regenerate the fault waveforms recorded by digital fault recorder (DFR). To counteract the PA’s inherent nonlinear distortions, a digital closed-loop modification technique that is different from the predistortion technique is conceived. And the experimental results verify the effectiveness of the fault waveform regenerator based on the digital closed-loop modification technique.

Neural network approach for modification and fitting of digitized data in reverse engineering~

Reverse engineering in the manufacturing field is a process in which the digitized data are obtained from an existing object model or a part of it, and then the CAD model is reconstructed. This paper presents an RBF neural network approach to modify and fit the digitized data. The centers for the RBF are selected by using the orthogonal least squares learning algorithm. A mathematically known surface is used for generating a number of samples for training the networks. The trained networks then generated a number of new points which were compared with the calculating points from the equations. Moreover, a series of practice digitizing curves are used to test the approach. The results showed that this approach is effective in modifying and fitting digitized data and generating data points to reconstruct the surface model.

DIRECT DIGITAL DESIGN AND SIMULATION OF MESHING IN WORM-GEAR DRIVE

A direct digital design method （DDDM） of worm-gear drive is proposed. It is directly based on the simulation of manufacturing process and completely different from the conventional modeling method. The loaded tooth contact analysis （LTCA） method is analyzed, in which the advanced surface to surface searching technique is included. The influence of misalignment errors and contact deformations on contact zone and transmission error （TE） is discussed. Combined modification approach on worm tooth surface is presented. By means of DDDM and LTCA, it is very conven- ient to verify the effect of worm-gear drive＇s modification approach. The analysis results show that, the modification in profile direction reduces the sensitivity of worm-gear drive to misalignment errors and the modification in longitudinal direction decreases the TE. Thus the optimization design of worm-gear drive can be achieved prior to the actual manufacturing process.

Managing Soil Erosion Potential by Integrating Digital Elevation Models with the Southern China's Revised Universal Soil Loss Equation——A Case Study for the West Lake Scenic Spots Area of Hangzhou,China

In China,many scenic and tourism areas are suffering from the urbanization that results from physical development of tourism projects,leading to the removal of the vegetative cover,the creation of areas impermeable to water,in-stream modifications,and other problems. In this paper,the risk of soil erosion and its ecological risks in the West Lake Scenic Spots (WLSS) area were quantitatively evaluated by integrating the revised universal soil loss equation (RUSLE) with a digital elevation model (DEM) and geographical information system (GIS) software. The standard RUSLE factors were modified to account for local climatic and topographic characteristics reflected in the DEM maps,and for the soil types and vegetation cover types. An interface was created between the Arcinfo software and RUSLE so that the level of soil erosion and its ecological risk in the WLSS area could be mapped immediately once the model factors were defined for the area. The results from an analysis using the Arcinfo-RUSLE interface showed that the risk value in 93 % of the expanding western part of the WLSS area was moderate or more severe and the soil erosion risk in this area was thus large compared with that in the rest of the area. This paper mainly aimed to increase the awareness of the soil erosion risk in urbanizing areas and suggest that the local governments should consider the probable ecological risk resulting from soil erosion when enlarging and developing tourism areas.

基于医院局域网的数字化手术室的改造与实现

介绍了某院现有数字化手术室的基本情况、改造的必要性及需求,阐述了基于医院局域网的数字化手术室改造的整体结构、信号传输与控制方式,比较了改造前后数字化手术室的配置方案和应用效果,指出了改造后的数字化手术室为工作人员提供了便利、快捷的临床工作环境,在提高工作效率的同时提升了手术转播和学术会议的质量,为其他医院数字化手术室的建设提供了参考。

Influence of high-temperature oxidation of SiC powders on curing properties of SiC slurry for digital light processing

Fabrication of silicon carbide(SiC)ceramics by digital light processing(DLP)technology is difficult owing to high refractive index and high ultraviolet(UV)absorptivity of SiC powders.The surface of the SiC powders can be coated with silicon oxide(SiO_(2))with low refractive index and low UV absorptivity via high-temperature oxidation,reducing the loss of UV energy in the DLP process and realizing the DLP preparation of the SiC ceramics.However,it is necessary to explore a high-temperature modification process to obtain a better modification effect of the SiC powders.Therefore,the high-temperature modification behavior of the SiC powders is thoroughly investigated in this paper.The results show that nano-scale oxide film is formed on the surface of the SiC powders by short-time high-temperature oxidation,effectively reducing the UV absorptivity and the surface refractive index(nʹ)of the SiC powders.When the oxidation temperature is 1300℃,compared with that of unoxidized SiC powders,the UV absorptivity of oxidized SiC powders decreases from 0.5065 to 0.4654,and a curing depth of SiC slurry increases from 22±4 to 59±4μm.Finally,SiC green bodies are successfully prepared by the DLP with the the oxidized powders,and flexural strength of SiC sintered parts reaches 47.9±2.3 MPa after 3 h of atmospheric sintering at 2000℃without any sintering aid.

载人月球探测整体性能提升总体技术

载人月球探测任务需要数千吨运载火箭起飞规模才能将航天员和少量载荷送达月面,实现高效探测难度很大。以提升载人月球探测任务整体性能为目标,在总体层面开展设计理念、设计方法、模型优化和数据修正的系统分析,提出了基于概率的总体设计、船/器/箭一体化设计、基于数字模型的优化设计、基于实测数据修正的总体性能提升等总体技术,结合载人月球探测任务总体设计实践,总结了技术应用效果,指出了后续研究方向,对于提升载人月球探测整体性能、发挥探测效益具有重要支撑作用。

数字服务合同单方变更权之规制

数字服务提供者常态化更新用户协议和应用程序。司法实践也认可其享有一般的、开放性的单方合同变更权,由此引发单方变更权与契约严守原则之间的冲突。并非任何改变均属于合同变更,不改变给付关系的日常更新不属于合同变更,不应过度夸大单方变更权的必要性。《电子商务法》《个人信息保护法》等法律并未确立数字服务提供者的单方合同变更权,唯有预先约定的单方变更权,才为法秩序所认可。在司法适用上,应通过格式条款规则规制约定的单方变更权条款,数字服务提供者应具体指出变更的情形、内容与影响,征得相对人的单独同意,并且自证变更权条款的合理性。数字服务提供者依约单方变更合同的,相对人也享有一定条件下解除合同的权利,且在合同解除后可以请求删除收集的个人信息,即使个人信息为服务的对价。

一种提高重载尼曼蜗轮副使用寿命的方法

针对重载尼曼蜗轮副使用过程中磨损严重的问题,从精确修形和数字建模两个角度,提出了一种提高重载尼曼蜗轮副使用寿命的方法。首先,提出对蜗轮进行齿廓修形的方法并设计出齿面修形的结构;然后,运用UG软件建立三维造型;最终,将修形后的蜗轮蜗杆传动应用于一些公司的冶金减速器装备中,良好的应用效果验证了设计的可行性和正确性。

数字化雷达人工影响天气作业指挥系统

人工影响天气作业指挥系统是提高火箭、高炮人工增雨和防雹效果的重要条件。应用C++和VisualStudio.net语言研制的新一代数字化雷达人工影响天气作业指挥系统,包括天气雷达监测、大气探测、火箭高炮作业指挥、作业信息通讯、作业效果检验、作业档案和资料管理6个子系统。文中对系统的设计原理、系统结构及主要功能进行了介绍。新一代人工影响天气指挥系统,适用于相关型号数字化天气雷达。应用效果表明,其具有一定的作业指挥能力和科技水平,功能界面友好、操作简单方便,是市级人工影响天气作业指挥人员的指挥平台。

现役导管架平台结构监测系统开发与数字孪生技术

目前我国海上有近1/3的导管架平台已超过或即将达到设计寿命,平台结构维护或修复延寿方面的需求比以往任何时候都更为迫切。传统的导管架水下结构损伤检测,测点少、难度大、费用高且无法预测平台结构的状态。开发了南海某导管架平台结构监测系统,该系统主要包括海上风浪的环境监测和平台结构振动、应变的响应监测。根据监测数据提出了基于双重有限元模型修正的现役导管架平台结构数字孪生,通过数字孪生技术修改平台结构安全评估及寿命预测模型,掌握海上导管架平台结构在整个服役周期内的结构行为,科学预测、预防性维护,以延长平台寿命。

一种修改建筑物底部DEM和DLG的实用方法

三维快速建模在实现三维数字城市建设进程中起着举足轻重的作用。针对JX-4G数字摄影测量系统测得的数字高程模型(DEM)和数字线划图(DLG),提出一种改进的方法,主要对建筑物底部的DEM和道路DEM处存在的不匹配问题进行修改,并对DLG数据中建筑物高度信息的缺失进行改进。改进后的DEM和数字正射影像图(DOM)能生成更高精度的数字表面模型(DSM),为高效率、高精度地建立三维数字城市模型奠定基础。

数字高程模型数据的无损数字水印

针对数字高程模型数据(简称DEM数据)提出广义直方图的概念,以DEM数据作为信息承载对象,采用修改广义直方图的方法嵌入水印信息,提取水印时不需要原始数据,水印提取后可完全恢复DEM数据,具有较高的经济价值。此方法计算复杂度低,适宜处理浮点精度的DEM数据,在保证较高峰值性噪比(平均42 dB)的同时嵌入信息量大(≥48.8 KB),带水印的DEM数据能很好地保持地形形状和起伏特征。

自适应神经模糊推理系统在电力故障重现中的应用

将电力故障录波数据重现为实际波形对于继电保护测试和保护动作行为分析等具有重要意义。文章将自适应神经模糊推理系统和数字闭环修正技术应用于电力系统故障重现装置中,实现了整体数字域内的闭环控制,利用输出端回采数据与原始数据进行比较并修正信号源的方法极大地减小了故障重现的非线性误差。Matlab仿真和基于该算法的故障重现装置的实际应用证明了自适应神经模糊推理在故障重现中应用的可行性和有效性。

一种基于直方图的可逆数字水印算法

文中提出一种可逆数字图像水印算法的改进方案,防止了原有算法中可能出现的像素值溢出情况。改进后的算法利用图像的灰度直方图,在图像进行分块的基础上进行像素灰度值的修改,实现在图像的空间域中嵌入较为充沛的水印信息。其中标志点的设定,可以有效防止灰度值在修改过程中出现上溢和下溢的情况,而密钥的使用不仅加强了水印信息的安全性,同时简化原有算法,减少了繁琐的记录信息。实验结果表明,算法在嵌入大量水印信息的情况下仍能取得满意的PSNR值。

数字填图技术“PRB”过程质量控制及常见问题整改方法——以路线地质调查为例

基于数字地质调查系统在1∶5万地质填图中的实际运用,总结了该系统在野外数据采集过程中出现的一系列问题,补充并完善了前人给出的解决办法;同时增加了"P"过程质量控制。此外,借助于数字地质调查信息综合平台(DGSInfo)和MAPGIS属性库管理子系统联合操作,给出了对室内补救后"PRB"过程属性库中混乱的属性数据进行快速修改的方法。

光电测微系统中的聚焦伺服控制

介绍了光电测微系统的基本原理及其构成,分析了该系统的关键环节即聚焦伺服系统,建立了音圈电机的数学模型。在此基础上,详细介绍了采用PID校正网络提高系统的稳定性和响应速度的方法,并用Matlab进行仿真,仿真效果令人满意。

基于数字闭环修正技术的故障重现放大装置

介绍了一种基于数字闭环修正技术的故障重现放大装置,包括其硬件结构和软件流程。该装置将数字闭环修正技术应用于故障重现放大,并采用自适应模糊智能控制算法,用反馈采样数据对故障信号源进行修正,克服了目前同类装置诸如功率放大器、继电保护测试装置等输出波形非线性失真严重的缺点,从而增强了故障重现放大装置的实用性。

面向数字化制造的工艺执行系统关键技术研究

针对目前企业工艺执行过程中存在的工艺执行力度不足、执行过程监控手段落后、现场信息反馈不及时等问题,提出了一套工艺过程控制系统的解决方案。通过对基于XML/XSL工艺数据无纸化浏览技术、基于RFID技术的生产过程控制与信息采集关键技术和基于系统集成的工艺临时更改关键技术的研究,加强了工艺执行的过程控制,实现了现场信息对生产相关部门的及时反馈,避免了人为失误造成的工程报废和质量事故。

采用倾斜摄影测量和几何造型方法的城市实景三维建模

近年来,数字城市在实景三维模型的基础上得到了广泛研究与应用。但是,传统三维建模手段难以满足现代数字城市更快速、更真实、更准确、更大规模的数据生产要求。本文以江苏省淮安市蒋坝古镇为例,开展快速构建城市精细化三维模型的研究,基于低空无人机倾斜摄影测量技术构建城市实景三维模型,利用几何造型方法对实景三维模型进行精细化加工。结果表明,采取的方案满足实景三维模型的应用需要,适合城市三维模型快速构建,对大规模三维模型数据生产具有一定的参考价值。