压铸铝合金表面强化新技术的研究与应用

将等离子体增强的电化学表面陶瓷化（PECC技术）工艺应用在压铸铝合金表面强化处理上，使其表面生成a－Al2O3和γ－Al2O3相的陶瓷膜，该膜在耐腐蚀、散热、电绝缘等性能方面均优于特富隆技术涂层。该处理工艺简单，可在常温下进行，具有很高的推广应用价值。     

大跨度三层与双层新型组合式平板网架结构

介绍一种新型组合式平板网架，以适应跨度在100m以上的特大跨度建筑中应用。用三层网架与两层网架合理组合，达到覆盖跨度大，以保证刚度和强度的条件下，作到节约用钢量的目的。     

基于ICE的CBTC仿真测试平台中间件的研究与设计

研究真实CBTC系统各模块之间的数据通信和协同操作,从而设计基于ICE的CBTC仿真测试平台的中间件,最终实现CBTC仿真测试平台各子系统模块之间实时地,稳定地,安全的通信,并且通过在中间件中实现底层自适应通信接口协议转换从而可以接入各厂家的真实设备,而且引入中间件使上层模块与操作系统解耦,实现各子系统模块的跨平台性.最后中间件完成之后,可以使得再次设计CBTC测试平台时将精力集中于业务逻辑的实现.     

基于B/S三层架构的中职师资培训测评系统的设计与实现——以安徽省中职师资培训测评系统为例

中职师资培训是加强中职师资队伍建设,提升中等职业教育能力的重要保障.培训测评是培训工作的重要环节,然而传统手工测评不仅浪费人力、财力,耗时长,也容易出错,同时还存在一些人为因素,使信息可靠性、真实性下降.针对以上问题,结合当前实用软件开发主流技术,以安徽省中职师资培训测评系统为例,研发了基于B/S三层架构的中职师资培训测评系统.设计的系统已在安徽省中职培训中心使用,性能稳定,运行效率较高.     

基于PLC两层三列升降横移立体车库控制系统设计

随着城市汽车保有量的不断增加,停车难成为大中型城市的普遍现象.运用PLC技术,以升降横移立体车库为研究对象,选择两层三列式车库为研究模型,在介绍立体车库工作原理的基础上,既进行了立体车库钢结构、载车板、机械传动和安全防护方面的硬件设计,又进行了PLC外部接线、电机控制线路、存取车控制流程和PLC控制程序梯形图方面的软件设计.经调试运行证明,能确保用户停车取车的方便、快捷和安全,实现停车取车智能化、高效化,且简便易行,既可大面积使用,又能见缝插针,还能与地面停车场、地下车库组合实施,最大限度地停放车辆,比较成功地解决目前大中型城市所面临的静态交通难题.     

A novel artificial noise aided security scheme to resist blind source separation attacks

In this paper, we discuss the physical layer security from a new angle of view and propose a novel approach to resist some attacks in signal processing perspective. The scenario considered in this paper is that the eavesdropper has the similar channel performance compared to the legitimate receiver. We design the optimal artificial noise （AN） to resist the attacks of the eavesdropper who uses the blind source separation （BSS） technology to reconstruct the secret information. For speech signals, the optimal AN is obtained by minimizing the maximum of the correlation coefficients between the source signal and the received signals at Eve and the correlation coefficients between the source signal and separated results of BSS. For binary phase shift keying （BPSK） signals, we maximize the minimum bit error rates （BERs） of the separated signals and the obtained signals at Eve. Moreover, we consider the AN design from the point of breaking the BSS conditions, and propose a method by changing the correlation coefficient randomly. The simulation results show that the AN we proposed has better performance than that of the white Gaussian AN to resist the BSS attacks for both speech signals and the BPSK signals.     

Observed and simulated features of the CO2 diurnal cycle in the boundary layer at Beijing and Hefei,China

The mechanism of the CO2diurnal cycle is a basis for investigating the carbon budget and its impacts on climate and environment change.Regional diurnal variations in CO2concentration based on observations and modeling have been studied widely.However,few studies have focused on the pattern of the CO2diurnal cycle in China.In this study,a three-dimensional global chemical transport model,Goddard Earth Observing System(GEOS)-Chem,was applied to simulate the CO2concentration and its variation over China from 2004 to 2012.Meanwhile,we also analyzed the CO2concentration as observed by two eddy covariance flux observation towers,one located in Beijing(39°580N,116°220E)and one in Hefei(31°550N,117°100E),using LI-COR 7500A infrared gas analyzers.Observations showed the amplitude of the CO2diurnal cycle at Hefei to be larger than at Beijing,due to stronger ecological activities.GEOS-Chem successfully captured the main aspects of the diurnal cycle of the CO2concentration in the boundary layer observed at both Beijing and Hefei.However,some discrepancies between the model and observations did exist;specifically,the model tended to underestimate the amplitude of the CO2diurnal cycle.The data also showed that traffic emissions significantly enhanced the CO2concentration in the boundary layer.     

完美传导边界条件不可压磁流体系统及解的注记

首先给出三种不可压磁流体方程组及其相互关系,其次给出这三种模型解的已有结果,最后指出由该模型衍生的相关公开问题.     

不同扩散角下汽车风洞试验段轴向静压系数

轴向静压系数是衡量汽车风洞试验段流场品质的重要参数.收集口角度影响轴向静压系数,它的改变对不同风洞表现出不一致的变化规律.通过研究不同风洞在不同扩散角下试验段轴向静压系数的变化发现,当扩散角为1.70°时,试验段轴向静压系数不随收集口角度的变化而变化;当它小于1.70°时,收集口角度越大,试验段轴向静压系数越大;当它大于1.70°时,变化规律相反.扩散角所导致试验段轴向静压系数变化规律的深层次的原因是,射流剪切层存在固定的耗散角,当扩散角等于耗散角时,收集口角度变大导致的扩散效应与外界气流进入带来的效应相同;当扩散角小于耗散角,收集口角度变大导致扩散效应更强.这揭示了收集口角度导致静压系数变化的机理,为风洞建设确定收集口和试验段等关键尺寸提供理论和设计参考.     

精原干细胞体外培养的方法改进

探讨精原干细胞体外培养优化方法,为进一步探讨其生物特征、生殖干细胞移植及生殖损伤及药物保护等研究提供实验基础.制备骨髓基质饲养层,将生后5 d~7 d雄性小鼠生精细胞接种在饲养层上,并于IMDM培养基及37 ℃下共培养,在倒置显微镜下观察细胞生长行为,并对培养后的细胞进行组织学、细胞化学、免疫组化、遗传学鉴定.精原干细胞能在以骨髓基质细胞饲养层上进行增殖和生长,且增殖后的表现出呈簇、团状生长,细胞间可表现出明显的胞质间桥,细胞核大,核/质比高,碱性磷酸酶及C-KIT受体阳性,染色体核型为20对(40条)等精原干细胞的生物学行为特征.原代培养的骨髓基质细胞作饲养层具有取材及制作简便等优点,且能在不添加外源性生长因子的前提下能通过自分泌足够的细胞生长因子,满足精原干细胞体外增殖和抑制分化的需要,是精原干细胞培养的一种良好的饲养层.IMDM培养基、血清及适宜的环境温度是精原干细胞体外培养的重要条件.