Phase I IASC-ASCE Structural Health Monitoring Benchmark Problem Using Simulated Data

Structural health monitoring (SHM) is a promising field with widespread application in civil engineering. Structural health monitoring has the potential to make structures safer by observing both long-term structural changes and immediate postdisaster damage. However, the many SHM studies in the literature apply different monitoring methods to different structures, making side-by-side comparison of the methods difficult. This paper details the first phase in a benchmark SHM problem organized under the auspices of the IASC–ASCE Structural Health Monitoring Task Group. The scale-model structure adopted for use in this benchmark problem is described. Then, two analytical models based on the structure—one a 12 degree of freedom (DOF) shear-building model, the other a 120-DOF model, both finite element based—are given. The damage patterns to be identified are listed as well as the types and number of sensors, magnitude of sensor noise, and so forth. MATLAB computer codes to generate the response data for the various cases are explained. The codes, as well as details of the ongoing Task Group activities, are available on the Task Group web site at 〈http://wusceel.cive.wustl.edu/asce.shm/〉.     

双动铝挤压机液压定针控制技术

介绍了双动卧式铝挤压机液压定针系统的结构、工艺流程及其自动控制系统。该控制系统响应快,定针精度高,具有很高的可靠性。目前该液压定针控制系统已应用于实际生产,定针控制精度≤1mm,完全满足工艺要求,对后续同类产品的设计起到了借鉴作用。     

高压换热器爆管的原因分析

对高压换热器爆管样品进行化学成分、力学性能、腐蚀产物和金相的检验,分析裂纹形成的原因。裂纹的产生是由应力腐蚀引起的。产生应力腐蚀有两个原因,一是换热管在制造过程中有磨损,表层形成形变马氏体。二是换热管弯管成形后弯管段消除应力热处理不彻底。     

纺织子管应用模式的应用研究

简要介绍了纺织子管技术的特点,详细阐述了纺织子管空管、叠加、小纺织管等应用模式的具体应用及应用时需注意的有关问题,并通过应用案例进一步阐述了纺织子管技术的优越性。     

Optimal design of a light commercial freezer through the analysis of the combined effects of capillary tube diameter and refrigerant charge on the performance

In this work, a discussion on a methodology to optimize the performance of a commercial freezer by using a simulation tool is presented. In order to provide a practical tool for deciding the best combination of refrigerant charge and capillary tube diameter, the results of the numerical studies are shown in the form of two-dimensional maps. The usefulness of this type of representation lies in the possibility of selecting the best operating point of the system, taking into account not only the efficiency or the power consumption but also the technical constrictions imposed by parameters such as the suction line temperature, the condenser subcooling, the evaporator superheat, and the run-time ratio. The discussion leads to the conclusion that the useful performance map is drastically reduced when all the operation requirements must be satisfied. Once the system design had been optimized, an additional numerical study, aimed at identifying the influence of the external conditions on the system behavior, was performed. The results show that the performance reduction can be effectively minimized modifying the refrigerant charge.     

保护层一次钻爆技术在三峡工程的研究与应用

从孔间、孔内双微差起爆和孔底设置柔性垫层分析“梯段炮孔加柔性垫层”的作用成因；从水平预裂和梯段孔深的确定分析“梯段炮孔加水平预裂”的作用成因，并通过试验及爆前、爆后检测和检查，说明这两种保护层一次钻爆技术理论上是可行的，在实践上很适合大中型水电工程保护层开挖。     

Tribological performance of UV picosecond laser multi-scale composite textures for C/SiC mechanical seals: Theoretical analysis and experimental verification

The performance of mechanical seals can be improved by using multi-scale composite textures with spiral grooves and micro-dimples, but without a clear texture function mechanism, it is difficult to optimize the textures on the sealing surface. This research established a mathematical model based on the mass-conservative JFO cavitation boundary to analyze the mechanical seal performance of multi-scale composite micro-textures. We use the multi-grid method for numerical solutions, investigate the hydrodynamic lubrication characteristics of composite-textured mechanical seals, and inspect the coupling effect of micro-dimples and spiral grooves. We also analyzed the influence of the geometrical parameters of composite textures on the sealing performance and optimized the sealing surface textures using theoretical analysis. The numerical analysis showed that the multi-scale composite-textured mechanical seal produced a coupling effect between the micro-dimples and spiral grooves, which improved the lubrication of the sealing pair. Eventually, C/SiC mechanical seal bench tests confirmed the tribological improvement of composite textures compared with the un-textured seal under various sealing liquid pressures and rotation speeds. Through comparing the Stribeck curve, the multi-scale composite textured C/SiC mechanical seals have a lower and more stable friction torque than the un-textured.     

Thumb push forces exertable by free-standing subjects

This study assessed the maximum pushing force that could be exerted by freestanding subjects, using thumbs only, on a small surface located in one of three horizontal positions at nine heights ranging from 13·5 to 169·9 cm above the floor. Each of 102 subjects made nine force exertion trials. Data are given on the cumulative percentages of subjects who could exert various forces at each of the 27 locations. An analysis of variance showed a highly significant effect due to location of the surface and highly significant interactions of location of the surface and trial presentation direction (top-down or bottom-up); of location of the surface and trial presentation pattern; and of location of the surface, trial presentation direction and trial presentation pattern. Maximum forces are exerted at about waist height and are increasingly reduced with increasing distances above and below the optimum location. Right-sided access to pushing surfaces is favoured over left-sided access.     

管束式集装箱的组装工艺和型式试验要求

大容积无缝钢瓶、管柬式集装箱和长管拖车作为专用气体储运装备在我国使用和制造已有10年时间，在检验检测和安全监管方面已基本形成相应的安全规范，但设计制造缺乏标准支撑。本文对管柬式集装箱的设计制造资质、组装工艺和型式试验要求进行简要介绍，包括大容积无缝钢瓶和长管拖车的相应要求。     

基于android和云平台的智能家居系统设计与实现

为解决智能家居系统大规模数据的存储、管理及移动终端的可靠接入等问题,本文设计了一种基于嵌入式家庭网关、Android和云平台服务的智能家居系统。利用极光云推送服务及时将家庭的异常报警信息推送到手机客户端,系统还提供了视频监控功能,用户随时随地通过手机查看家庭动态。当监测异常时会自动拍照记录异常场景,并上传至yeelink物联网云平台,进行图像云存储。另外通过手机客户端可以查看所选时间范围内的报警图像,随时掌控家庭生活。