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采用焊条电弧焊方法对ADB610钢进行焊接,对焊接接头进行疲劳裂纹扩展试验,研究其概率疲劳裂纹扩展规律.采用两步七点递增多项式拟合方法,计算了一系列相同裂纹长度下母材区、热影响区和焊缝区的对数裂纹扩展速率方差和存活率分别为50%,90%,95%,99%,99.9%的裂纹扩展速率.结果表明,总体上母材区的裂纹扩展分散性最小,热影响区其次,焊缝区分散性最大;而且总体上存活率相同时,在裂纹扩展的初期,母材区的裂纹扩展速率最快,焊缝区的裂纹扩展速率最慢;在裂纹扩展末期,三区域的裂纹扩展快慢相当;随着存活率增大,三区域裂纹扩展快慢差别不大时所对应的裂纹长度减小. 相似文献
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在当今的数字世界中,手机的应用范围越来越广。在手机这种特殊设备里,经常会存取一些数据,例如:音频文件、视频文件、图片文件和通讯录等数据。Android作为一种手机操作系统,提供如下几种存取数据的方式:Preference(配置)、File(文件)、SQLite数据库和网络等。本文将着重阐述SQLite数据库技术在Android平台的应用。 相似文献
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支持协同工作是最重要的数据库应用之一。分析CSCW对数据库的要求,并从科研角度出发,具体阐述分布式数据库、时态数据库、实时数据库、主动数据库、移动对象数据库、时空数据库以及其它数据库(如协同数据库、多版本数据库等)等新一代数据库技术在CSCW中的应用。 相似文献
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An adaptive deadbeat (ADB) controller was developed to investigate its capability in providing a fast frequency response to an electrical power system. This controller was developed to meet the requirements of the National Grid System Operability Framework (SOF), which requires frequency to be accelerated in line with a fast rate of change of frequency (RoCoF) when a high rate of nonsynchronous machines are presented. The controller’s parameters were optimized using particle swarm optimization (PSO) to ensure a robust operation and to maintain the proper operation of the power system. The design of the ADB controller was then integrated with the multiarea model of the north and south zones of Scotland. This model was developed in order to conform to the future energy requirements scenario stated by National Grid whereby regional control can be provided in both the north and south of Scotland. In comparison with the standard PI and Fuzzy-PI controllers used in the four highlighted case studies, it was shown that the ADB controller was able to significantly reduce the RoCoF and deviation of frequency when a sudden loss of generation occurred in a low inertia zone. The ADB also showed high robustness against a wide range of operating conditions. 相似文献
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Christiane Jasmin Reinert‐Weiss Holger Baur Sheikh Abdullah Al Nusayer David Duhme Norbert Frühauf 《Journal of the Society for Information Display》2017,25(2):90-97
Conventional adaptive driving beam headlamps are limited in achieving still higher quantities of switchable pixels by the number of LEDs and movable elements needed. In this paper, it is shown that by integrating an active matrix liquid crystal display module, it is possible to realize fully adaptive high‐resolution headlights without mechanical elements and a finite number of LED with 30 k switchable pixels. 相似文献
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对ENAA合同条件以及多边开发银行基于ENAA的改编版合同进行简要介绍,并选取亚洲开发银行2021年12月发布的《设备设计-供应-安装采购合同》和2017版FIDIC黄皮书,着重针对通用合同条件就两者差异进行对比分析。 相似文献
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Public-private partnerships (PPPs) offer possible solutions for governments seeking to achieve better value for money and fund the investments needed to provide infrastructure and manage public services. Water-sector projects demand extensive, up-front and sunk investments, and inefficiency levels are often significant. This study conducted a systematic review of previous research on water sector PPP projects. The research design is innovative in that it relied on a hybrid methodology combining systematic quantitative, semantic network and narrative analyses. The literature review protocol applied found 122 relevant studies published in top journals. Five key topics within water-related PPP studies were identified: risk management, PPP contractual arrangements, financing and tariffs, infrastructure, and governance. The most important topic is risk management, within which individual scholars’ contributions were tracked. However, a consensus has not been reached about the best risk matrix for improving PPP contracts in the water sector. 相似文献
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