复杂军工产品虚拟试验验证技术研究与发展

虚拟试验验证是一种基于数字样机模型的复杂产品关键系统试验数据产生、获取和分析的系统工程过程;文中从支撑框架、验证范围、试验环境和标准化等方面分析了国外该领域最新的发展趋势,结合十一五国内虚拟试验领域的典型研究和应用现状,对现阶段军工产品虚拟试验验证领域的研究成果进行了总结;在此基础上,分析了十二五试验与测试领域的研究重点,提出了虚拟试验验证技术领域研究的发展设想,并对VITA技术框架进行了着重阐述;最后,给出了发展我国虚拟试验验证技术的建议。     

基于VNX总线的航天飞行器综合控制系统设计

针对小型化航天飞行器对综合控制系统的需求,结合目前国内外先进飞行器综合航电应用的经验,设计了一种以VITA74总线为基本架构的综合控制系统,使其在性能、功耗、体积等方面产生了大幅提升。利用SiP芯片内部的双核SoC芯片来运行主控程序及导航控制算法等功能,通过芯片集成的接口资源和可编程逻辑资源实现丰富的外围接口。给出了综合控制系统的硬件系统设计、软件系统设计及结构设计方案,并详细介绍了各个功能模块的设计思想。通过相应的性能测试试验,表明该系统工作正常,各项性能指标满足任务需求,可用于未来航天飞行器的使用。     

VPX和ATCA机箱管理关系及异同

通过深入研究基于多协议交换总线（ Verstatile Protocol Switch Bus, VPX）机箱管理和高级通信计算架构（ Advanced Telecom Computing Architecture, ATCA）系统机箱管理规范,结合开发VPX和ATCA机箱管理的经验,总结和提炼出二者机箱管理的异同,以利于读者在学习和开发VPX机箱管理应用时,能够对VPX机箱管理有一个迅速的认识和理解,并能够充分借鉴和利用ATCA机箱管理开发的经验和成果。对比分析结果表明, VPX机箱管理是在ATCA机箱管理的基础上派生和发展而来。     

Adhesion of metal brackets to glassy matrix and hybrid CAD/CAM materials after different physico-chemical surface conditioning

This study compared the adhesion of metal brackets bonded to different CAD/CAM materials after various surface conditioning methods. CAD/CAM blocks (N = 204, n = 17 per group) of (a) VITA Mark II (VM), (b) IPS e.max CAD (IP), (c) Lava Ultimate (LU), and (d) VITA ENAMIC (VE) were conditioned with one of the following methods: C-Control: (fine diamond bur); CJ: (fine diamond bur + air-abrasion with 30 μm SiO₂ + silane), and HF: (fine diamond bur +9.5% hydrofluoric acid + silane). Metal brackets were bonded to the conditioned surfaces of the specimens, stored in artificial saliva for 24 h at 37 °C and thermocycled (×1000). Subsequently, the brackets were debonded under shear in a Universal Testing Machine (1 mm/min). Failure types were analyzed under scanning electron microscope. Data were analyzed using two-way ANOVA and Tukey’s tests (α = 0.05). Two-parameter Weibull distribution values, including the Weibull modulus, scale, and shape, were calculated. Mean bond strength (MPa) values were significantly affected by the surface conditioning method (p < 0.001) but not the CAD/CAM material type (p = 0.052). Bond strengths for all CJ and HF-conditioned specimens were twofold higher (11.83 ± 1.95 ? 9.44 ± 1.63) than those for control specimens with all materials (4.73 ± 0.93 ? 6.02 ± 0.69). Lower mean values were obtained in LU-CJ (9.78 ± 1.61) and LU-HF (9.44 ± 1.63) than those for other groups (11.83 ± 1.95 ? 10.93 ± 1.33) groups (p < 0.05). Weibull distribution showed higher shape values for VM-CJ (11.26) and VM-HF (8.87) than those for other groups (0.82–1.83). In control groups, exclusively adhesive and after conditioning mainly mixed failures were observed. Chairside silica coating or HF conditioning significantly improved metal bracket adhesion to both glassy matrix and hybrid CAD/CAM materials tested, with the most reliable adhesion being observed for feldspathic ceramic.     

基于VPX总线的抗恶劣环境计算机

随着FC,PCI-Express,RapidIO,Hypextransport等高速串行总线的快速发展,I/O模块对计算机的内部总线速度要求不断提高,高性能和高可靠性成为抗恶劣环境计算机设计中的一对矛盾.该文提出一种采用VPX总线的抗恶劣环境计算机设计方案,为高性能、高可靠性计算机的实现提供了技术途径.     

Momentum transfer in a fixed-bed reactor described by the surface renewal model

This paper presents experimental measurements and theoretical predictions of the velocity gradient in a fixed-bed reactor with single phase liquid flow. The local measurements are carried out by means of microelectrodes embedded in the packing of the bed, whereas the corresponding predictions are based on the surface renewal model. The fluid elements age distributions, needed in the surface renewal model, were determined using the variable-interval time-averaging (VITA) method. The parameters of VITA method, i.e. local interval time-averaging length a and threshold level k, were optimally selected and are equal to 3T_C (T_C is the integral time deduced from auto-correlation functions) and 0.9, respectively. It was shown that the surface renewal model is appropriate for predictions at high liquid flow rates, corresponding to a flow that behaves like a turbulent flow. Moreover, it was shown that with only one velocity gradient signal measurement, both experimental and theoretical values are obtained for a specified flow rate. The average value of the signal provides the experimental measurement, whereas its fluctuating part yields the corresponding theoretical prediction.     

VITA新标准及其在雷达系统中的应用

VME总线以其标准化程度高、可靠性好、系统开放的特点,在军用嵌入式计算机、航空航天、工业控制等可靠性专业领域得到了广泛应用。尽管经过数次升级,传统VME总线标准已难以满足飞速增长的数据处理量和发热量的需要。为了获得更大的带宽和更强的制冷能力,国际贸易协会组织已开始制定并推出新的标准以应对这些挑战。文中详细介绍了VITA41/46/48等标准,并分析了其在综合航电系统,雷达系统等场合的应用前景。通过比较发现,VITA 46/48标准非常适合LRM模块标准的要求,可作为制定我国LRM模块标准的重要参考。