Transmission system restoration with co-optimization of repairs,load pickups,and generation dispatch

This paper studies the restoration of a transmission system after a significant disruption such as a natural disaster. It considers the co-optimization of repairs, load pickups, and generation dispatch to produce a sequencing of the repairs that minimizes the size of the blackout over time. The core of this process is a Restoration Ordering Problem (ROP), a non-convex mixed-integer nonlinear program that is outside the capabilities of existing solver technologies. To address this computational barrier, the paper examines two approximations of the power flow equations: The DC model and the recently proposed LPAC model. Systematic, large-scale testing indicates that the DC model is not sufficiently accurate for solving the ROP. In contrast, the LPAC power flow model, which captures line losses, reactive power, and voltage magnitudes, is sufficiently accurate to obtain restoration plans that can be converted into AC-feasible power flows. An experimental study also suggests that the LPAC model provides a robust and appealing tradeoff between accuracy and computational performance for solving the ROP.     

螺栓角钢钢节点的三维非线性有限元分析

对螺栓角钢钢节点半刚性连接采用非线性有限元分析方法 ,对连接中的主要构件的顶部、底部、腹板角钢、高强螺栓、梁翼缘、柱翼缘和柱翼缘加劲肋进行三维非线性有限元精细模拟 ,针对有无柱加劲肋、有无腹板角钢等几种连接的情况进行比较分析 ,探讨了螺栓角钢半刚性连接的受力性能。     

海量数据库迁移与升级

目前数据库中数据越来越多,应用对数据库在线时间的要求也越来越高,使得数据库迁移和数据库升级成为了一件非常困难的事情.为此,介绍了几种迁移和升级的方法,用以实现以尽可能少的停机时间对TB级数据库完成数据库的迁移和升级.     

护坡工程空心螺母块立浇及安装施工技术研究与应用

空心螺母块因其外形简单,近年来在河湖生态护坡工程中被广泛应用。但护坡工程使用的空心螺母块数量较多,传统的平浇法预制,所需预制场地大且平整度要求高,螺母块运输安装费时费力、外观质量难以保证。文章针对护坡工程空心螺母块浇筑和安装的特点研究出一种操作简便、切实可行的连续立浇预制安装的施工方法,经过工程实际应用,有效保证了预制块的浇筑质量,提高了预制块的运输铺设效率,节约了预制场地的兴建面积。     

Accurate positioning of a drilling and riveting cell for aircraft assembly

Modern aircraft assembly demands assembly cells or machines with higher machining efficiency and accuracy. Thus, a dual-machine drilling and riveting cell is developed in this paper. We firstly discuss its physical design, as well as the automatic drilling and riveting process. With the automatic drilling and riveting cell, drilling and riveting production line of aircraft panels can be expected. The frame chain of the drilling and riveting cell is constructed to link the assembly cell to its task space, which is the kinematics base. System calibrations, including task space calibration, the sensor calibration of an orientation alignment unit, the floating calibration of the implicit hand-eye relationship, are explored. For high positioning accuracy, a multi-sensor servoing method is proposed for cell positioning. An orientation-based laser servoing strategy, which uses the feedback of the orientation errors measured by laser displacement sensors, is used to align drilling direction and camera shooting direction. Besides, A single-camera-based visual servoing is applied to align the tool center point (TCP) to reference holes, to obtain their coordinates for drilling position modification. Experiments of multi-sensor servoing for cell positioning are performed on an automatic drilling and riveting machine developed for the panel assembly of an aircraft in China. With the cell positioning method, the automatic drilling and riveting cell can approximately achieve an accuracy of 0.05 mm, which can adequately fulfill the requirement for the assembly of the aircraft.     

预应力中空棒构件设计与力学特性

为满足装配式建筑节点接缝混凝土抗震性能的需要,以一种自平衡预应力中空棒为研究对象,研究接缝位置短杆件施加预应力的效果。根据力的平衡机理,对结构内部钢棒施加压力使结构外部钢管协调受力拉伸,达到设计预应力后由螺母锁定,将杆件埋入到装配式节点接缝混凝土,浇筑早强灌浆料,待固结达到预定强度释放反力棒,依靠外螺纹结构与混凝土的粘结力自锚实现接缝混凝土施加预应力。力学性能分析方面,研究杆件张拉阶段、静置松弛阶段应力变化及损失情况,验证了杆件张拉完成至放张前应力存储的有效性,通过分析杆件放张后应力分布、预应力损失等参数,验证了杆件应用到节点混凝土后传递应力的机理及有效性,并采用有限元方法分析预应力混凝土构件应力分布规律。研究结果表明预应力中空棒技术作用于装配式节点接缝混凝土具有较高的抗震和耗能能力,对装配式建筑节点混凝土高抗震性能的实现提供了一种新的技术手段。     

一种优化内容适配技术的设计与实现

针对传统内容适配技术的特点和目前手机浏览器的发展现状,本文提出优先适配浏览器的内容适配技术。在传统内容适配技术上增加uA特征串和Accept特征串作为内容适配参数,并设计浏览器优先终端、终端优先Accept的适配规则。综合网络侧适配和终端侧适配优点,有效优化终端上的内容适配率,使得终端能够动态地、智能地针对不同的手机浏览器适配最佳的浏览版本。     

浙江省水利管理与服务能力现代化发展水平评价

遵循独立、科学、系统、层次和可操作性的原则,在充分分析国内外大量相关指标的基础上,结合浙江省实际情况,提出了包括防汛防台抗旱管理、水利工程管理、水行政管理、水利工程完好率、人才保障能力、资金保障能力等6项准则层的浙江省水利管理与服务能力现代化发展水平评估指标体系,在此基础上利用模糊聚类循环迭代法科学确定指标权重,并构建了发展水平综合评估模型。对浙江省2015年的水利管理与服务能力现代化水平进行评价,将结果与2020年的预期值进行对比,查找问题和薄弱环节并提出对策建议。     

如何实现SAP ERP财务报表的灵活定制

如何使得一个不具备ABAP编程语言基础的财务用户能在SAP系统中快速有效地配置财务报表,并灵活定义输出格式,是许多实施SAP ERP系统的公司都会遇到的问题。本文介绍的财务模块报表定制功能旨在SAP ERP中构建一个可视化图形界面,在这个界面中定义报表、报表版本,以及每个版本的输出布局、报表行、报表列、报表单元格的取数逻辑等要素,使得用户在不使用编程工具的前提下实现报表的灵活定制。     

企业节能减排的监控系统研究

经济发展与节能减排是一个矛盾的统一体,如何在二者之间进行平衡,考验着中国人的智慧。通过行业分类选取恰当的节能减排指标、采用统计学的基本原理、应用质量控制的技术与方法,提出了节能减排的指标体系和监控方法,以期对节能减排实施动态监控,对我国现阶段的企业节能减排工作有着重要的参考价值。