Surface stress and strain fields on compressed panels of corrugated board boxes. An experimental analysis by using Digital Image Stereocorrelation

The complex behaviour of corrugated board packages under compression loading is investigated in this work. Original experimental data are obtained by using a Digital Image Stereocorrelation technique for measuring the displacement and strain fields of the panels’ outer liner of the tested boxes. The stress field is also estimated by accounting for the anisotropic mechanical behaviour of the outer liner, its residual stress state induced by the processing of the corrugated board and the effects of box manufacturing operations and compression. Results show that these fields are extremely heterogeneous on the panels’ surface. Most stressed areas are located along the panels’ edges. The elastic limit of the outer liner is reached quite soon during compression. Box geometry and panel flaps are of primary importance on the observed phenomena. This approach delivers useful information to improve kinematic and constitutive assumptions for buckling and post-buckling models of boxes or thin-walled sandwich structures.     

石膏板吊顶石膏板隔墙的施工

为防止石膏板吊顶及石膏板隔墙裂缝的出现,简述在其制作工艺中应注意的事项。     

河南艺术中心标志塔工程施工技术研究与应用

针对河南艺术中心工程标志塔结构特点及施工难点,探讨了标志塔钢结构及玻璃幕墙结构的施工工艺,并充分应用施工图深化优化设计技术、计算机放样下料技术、大型管材相贯线多维数控切割技术、激光(全站仪)测量技术及单机吊装处理技术等,编制科学合理的施工方案,从最优化施工方案本身提高安装精度和加快施工进度。     

磁路独立组合转子复合励磁发电机的设计

复合励磁发电机在移动电源领域有着广泛的应用前景。该文提出了一种磁路独立组合转子复合励磁发电机,介绍了其结构和磁路特点。在此基础上,提出了电机的电磁设计方法,并推导了电机重要参数E0、Xad、Xaq的计算方法。设计了一台额定功率为25kW的样机,样机试验结果表明,设计计算值准确,电机性能均达到了要求。     

基于Qt/Embedded的断路器故障诊断专家系统

设计了基于Qt/Embedded多线程机制的断路器故障诊断专家系统,提出一种综合故障仿真、故障模拟、数学模型分析结果及业内专家经验、文献资料等建立断路器故障诊断专家系统知识库的方法。针对断路器知识库的特点,选用产生式规则及框架表达知识,设计了专家系统的推理机制。最后,对专家系统的有效性进行了试验验证。     

漏电断路器的故障分析

简单介绍了漏电断路器的性能和保护种类,举例说明漏电断路器的常见故障现象及原因分析。     

微型程序控制器在低压供电系统中的应用

在低压供电系统中通常利用传统继电器设计控制线路,主要是因为复杂的接线造成的低可靠性和不能灵活地满足用户不同的控制要求。在低压供电系统中用微型程序控制器代替传统继电器可以显著地提高可靠性,可以灵活地满足用户不同的控制要求,大大提高了成套开关设备的性价比。     

金属氧化物避雷器短路试验(压力释放试验)的重要性分析

为了保证避雷器即使发生故障也不会损坏其他设备或者影响人身安全,短路试验是一项非常重要的试验。由于试验回路电压或容量的关系,在有些短路试验中,避雷器的短路电流第一个峰值达不到要求的试验电流有效值的1.7-2.5倍,通过短路电流的时间往往也不足0.2秒。如果所进行的试验不符合这一要求,将不能真正考验避雷器压力释放装置是否能够起到防爆作用。     

Selection of minimal tripping times for distance protection using fault trees with time dependencies

Correct coordination between protection relays is an essential requirement to maintain stability and integrity of electrical power systems. Time settings of protection relays have to be adapted to time characteristics of electrical power systems and time settings of other protections. In the paper, fault trees with time dependencies (FTTD) are used for selecting time delay settings of remote back-up distance protections. In FTTD, events and gates are characterized by time parameters, which are derived from time characteristics of protection devices and the inherent delays of protection equipment. Two case studies are presented. First, the coordination of protections for the simple transmission line composed of two identical sections is studied. Next, the transmission line that contains two sections of different lengths and transformer between them is analyzed. In both cases, formulae for time delays of protections are derived. According to calculations executed for the first case, our method gives time delays that often are significantly smaller than values suggested by generally recommended and accepted rules.     

LTB145D1／B-2STANDS型断路器储能回路缺陷分析及改进方法

通过分析LTBl45D1／B-2STANDS型断路器储能装置工作原理及故障原因,提出了可靠的改进方案,使得在弹簧未储能的情况下能可靠闭锁合闸回路,同时也能有效保护储能电机。