无线ILC系统测控信号延时效应补偿方法

针对通过无线信道进行测控信号传输的远程迭代学习控制( ILC)系统,研究信号传输延时对控制系统性能的影响.分析了测控信号延时情况下ILC系统的收敛性问题,通过引入预控制向量,提出了ILC系统信道延时效应补偿的向量更新方法.数值仿真结果表明了所提方法的有效性.     

基于消息队列和XML的数据同步技术研究

数据同步技术一直是影响分布式计算机系统应用的一个决定性因素,在简单介绍了现有的数据同步技术的基础上,提出了采用Windows的消息队列和二进制XML编码技术相结合的数据库同步方案,给出了具有较高数据压缩比率的二进制XML编码算法,实现了在窄带网络环境下的数据同步,并对数据同步的导入导出策略进行了设计,仿真测试的结果表明该同步算法相较于传统的数据同步算法具有很好的网络传输特性及数据同步的可靠性,这些对于数据同步技术的研究,在理论与实践上都有一定的借鉴意义。     

基于消息队列和XML的数据同步技术研究

数据同步技术一直是影响分布式计算机系统应用的一个决定性因素,在简单介绍了现有的数据同步技术的基础上,提出了采用Windows的消息队列和二进制XML编码技术相结合的数据库同步方案,给出了具有较高数据压缩比率的二进制XML编码算法,实现了在窄带网络环境下的数据同步,并对数据同步的导入导出策略进行了设计,仿真测试的结果表明该同步算法相较于传统的数据同步算法具有很好的网络传输特性及数据同步的可靠性,这些对于数据同步技术的研究,在理论与实践上都有一定的借鉴意义。     

The Nature of Struck-by Accidents

Construction accidents are broadly categorized into five basic groups, namely falls (from elevation), shock (electrical), caught in/between, struck-by, and other. “Struck-by” accidents accounted for 22% of all construction-related fatalities recorded by the Occupational Safety and Health Administration between 1985 and 1989. Recent (1997 to 2000) data show that the percentage of struck-by accidents constituted 24.6% of the fatalities and serious construction worker injuries. Struck-by accidents primarily involve workers struck by equipment, private vehicles, falling materials, vertically hoisted materials, horizontally transported materials, and trench cave ins. Determining possible causation factors of these accident types is often difficult, due to the broad categories utilized in the accident coding system. This study resulted in gaining insights about the root causes of the struck-by injuries. By finding the root causes, effective methods for accident prevention can be developed.     

Impact of metallonucleases on DNA interactions: Structural validation and in-vitro antibiogram assay

Four novel complexes were synthesized using 2-aminobenzophenone Schiff base precursor and characterized by various analytical techniques. FT-IR results demonstrate that the Schiff base ligand, obtained by the condensation of 2-aminobenzophenone with 2-hydroxybenzaldehyde, coordinates to the metal ion via azomethine nitrogen, phenolic oxygen and carbonyl groups. Furthermore, the intercalative mode of these octahedral complexes with calf thymus (CT) DNA has been explored using absorption spectra, cyclic voltammetric and viscosity measurements. Gel electrophoresis assay demonstrates the effective cleaving aptitude of pBR322 DNA by complexes in the presence of an activating agent (H₂O₂). Moreover, the in-vitro biological activities of metal complexes have been screened against few pathogenic bacterial and fungal strains by well diffusion technique. It is found that all the complexes show potential activities as compared to the free ligand. These findings may lead to develop novel DNA targeting metallonucleases.     

城市级CORS系统中控制中心的设计与实现

CORS系统中控制中心是系统的核心,正确的控制中心设计可以确保系统的正常运行,保证系统工作的稳定与可靠。城市级CORS系统多由几个到十几个参考站组成、针对不同应用要求,可以有不同的控制中心设计,从而保证最优的系统性能与最优的性价比。     

Adjusting physicochemical and cytological properties of biphasic calcium phosphate by magnesium substitution: An in vitro study

Biphasic calcium phosphate (BCP) is a highly study bone defect repair material with adjustable degradation, perfect osteoconduction and good osteoinduction. As one of the essential trace elements, magnesium (Mg) possesses the abilities of pro-osteogenesis and pro-angiogenesis. Therefore, Mg doping may further expand the application of BCP in bone defect repair, but few studies focus on promoting the osteogenesis and angiogenesis of BCP simultaneously by Mg doping, and the optimal doping amount of Mg remains to be explored. In this study, the physicochemical and biological properties of BCP scaffold affected by Mg doping were systematically study. Results showed that Mg doping enhanced the sintering of BCP scaffold, resulting in the decrease of degradation rate at the initial soaking period. However, the introduction of Mg damaged the lattice stability of BCP, leading to the increase of BCP degradation rate at the later soaking period. BCP scaffolds with Mg doping content ≥3 mol.% could achieve a long-term sustained release of Mg. The ion microenvironment created by Mg-doped scaffolds was simultaneously conducive to the osteogenic differentiation of stem cells and the enhanced angiogenic activity of endothelial cells. The scaffold doped with 5 mol.% of Mg (Mg5–S) showed the highest efficiency in promoting osteogenic differentiation. Mg-doped BCP scaffolds with a doping content ≥3 mol.%, especially Mg5–S, significantly improved the proliferation and angiogenic differentiation of endothelial cells. Based on these, we believe that the optimal doping content of Mg in BCP is 5 mol.%, and Mg5–S has great application potential in bone defect repair.     

舒展原理及应用

在一个完美的生产过程中，很少会需要舒展，纸幅会保持均匀平直。现实情况非常不同，绝大多数的成幅材料在处理过程中需要舒展，以防止或去除折皱，扩展幅面或在复卷分切过程中分开。成形网和干网的舒展是属于较少的无端材料的舒展情况。笔者在工作过程中发现国内纸厂的工程师和纸机操作人员普遍对它的机理不太了解甚至误解，这样不利于它的选型、操作和维护。因此基于工作的便利组织了此文。本文旨在介绍相关知识，启发思维，提高生产力。     

深大基坑施工过程中地下水的控制对周边环境的影响

在深基坑施工过程中,基坑地下水控制对周边环境的影响很大,一旦处理不慎,极易造成工程周边道路沉降、管线破坏、房屋倾斜开裂等问题.为此,通过某典型工程的实践,从基坑地下水控制出发,对周边环境的影响作了研究分析,并制定了相对应的技术措施,取得了良好的效果.     

Experimental and numerical analysis of BGA lead-free solder joint reliability under board-level drop impact

Board-level solder joint reliability is very critical for handheld electronic products during drop impact. In this study, board-level drop test and finite element method (FEM) are adopted to investigate failure modes and failure mechanisms of lead-free solder joint under drop impact. In order to make all ball grid array (BGA) packages on the same test board subject to the uniform stress and strain level during drop impact, a test board in round shape is designed to conduct drop tests. During these drop tests, the round printed circuit board assembly (PCBA) is suffered from a specified half-sine acceleration pulse. The dynamic responses of the PCBA under drop impact loading are measured by strain gauges and accelerometers. Locations of the failed solder joints and failure modes are examined by the dye penetration test and cross section test. While in simulation, FEM in ABAQUS software is used to study transient dynamic responses. The peeling stress which is considered as the dominant factor affecting the solder joint reliability is used to identify location of the failed solder joints. Simulation results show very good correlation with experiment measurement in terms of acceleration response and strain histories in actual drop test. Solder joint failure mechanisms are analyzed based on observation of cross section of packages and dye and pry as well. Crack occurred at intermetallic composite (IMC) interface on the package side with some brittle features. The position of maximum peeling stress in finite element analysis (FEA) coincides with the crack position in the cross section of a failed package, which validated our FEA. The analysis approach combining experiment with simulation is helpful to understand and improve solder joint reliability.