Robust topology optimization under multiple independent uncertainties of loading positions

The topology optimization problem of a continuum structure is further investigated under the independent position uncertainties of multiple external loads, which are now described with an interval vector of uncertain-but-bounded variables. In this study, the structural compliance is formulated with the quadratic Taylor series expansion of multiple loading positions. As a result, the objective gradient information to the topological variables can be evaluated efficiently upon an explicit quadratic expression as the loads deviate from their ideal application points. Based on the minimum (largest absolute) value of design sensitivities, which corresponds to the most sensitive compliance to the load position variations, a two-level optimization algorithm within the non-probabilistic approach is developed upon a gradient-based optimization method. The proposed framework is then performed to achieve the robust optimal configurations of four benchmark examples, and the final designs are compared comprehensively with the traditional topology optimizations under the loading point fixation. It will be observed that the present methodology can provide a remarkably different structural layout with the auxiliary components in the design domain to counteract the load position uncertainties. The numerical results also show that the present robust topology optimization can effectively prevent the structural performance from a noticeable deterioration than the deterministic optimization in the presence of load position disturbances.     

一种高速延时无关同异步转换接口电路

针对传统片上系统设计同步时钟引起的功耗大、IP核可重用性差等缺点,提出一种可用于多核片上系统和片上网络的快速延时无关同异步转换接口电路.接口由采用门限门的环形FIFO实现,移除了同步时钟,实现了数据从同步时钟模块到异步模块的高速传输,支持多种数据传输协议并保证数据在传输中延时无关.基于0.18μm标准CMOS工艺的Spice模型,对3级环形FIFO所构成的传输接口电路进行了仿真,传输接口的延时为613ps,每响应一个传输请求的平均能耗为3.05pJ?req,可满足多核片上系统和片上网络芯片速度高、功耗低、鲁棒性强和重用性好的设计要求.     

国外二硝基茴香醚基炸药发展现状

为及时了解国外二硝基茴香醚(DNAN)炸药技术的发展现状,在系统跟踪国外技术文献和研发动态的基础上,综述了DNAN基炸药的配方设计、制备工艺、环境健康评估和装备应用等最新研究与进展。从中分析得出:美国DNAN基炸药技术发展最迅速,DNAN基炸药配方研究活跃,有多种配方已达到实用化水平;DNAN基熔铸炸药的环保和安全特性明显优于TNT,预示着其在不敏感弹药中具有广泛的应用前景;美军率先大规模装备IMX-101和IMX-104炸药并部署部队,标志着大口径炮弹炸药主装药的不敏感化换装已进入实施阶段;对DNAN的研究提出了建议,应重点发展DNAN基高性能熔铸炸药配方、先进制备工艺技术及应用技术。     

钝感推进剂研究进展及发展趋势

介绍了低易损炸药钝感机理和几种新型钝感推进剂的研究进展,总结了降低推进剂感度的技术途径及其发展趋势,认为对降低推进剂感度的含能黏合剂和真正钝感氧化剂的研制及其在推进剂中的应用将是今后研究的重点工作。     

Storytelling as a foundation to literacy development for Aboriginal children: Culturally and developmentally appropriate practices.

There is substantial evidence that Aboriginal youth face serious challenges in schooling, in general, and in literacy development, specifically. Thus, it is essential to design early literacy programmes that engage Aboriginal children and produce positive outcomes. In this article, the authors propose that such programmes include oral storytelling by teachers and students because it is a precursor to reading and writing across cultures and a traditional Aboriginal teaching tool. Moreover, storytelling fits with Aboriginal epistemology--the nature of their knowledge, its foundations, scope, and validity. The authors begin by reviewing a representative sample of the research that has examined the outcomes of early literacy instruction with Aboriginal children. Next, the authors describe Aboriginal epistemology, highlighting the role of the oral tradition. Finally, the authors describe an ongoing study aimed at supporting early literacy development through a developmentally and culturally appropriate oral storytelling instruction programme. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

ε-支持向量回归机算法及其应用

针对现有传统的一些图像去噪方法难以获得清晰图像边缘的问题,提出了利用ε-SVR技术构建图像去噪滤波器的新方法。ε-支持向量回归机通过引入ε不敏感损失函数,可以实现具有较强鲁棒性的回归,而且回归估计是稀疏的,保留了SVM的所有优点。分析了ε-支持向量回归机理论算法及其在图像去噪中的应用,使用ε-支持向量回归机对图像进行滤波并且与最小值滤波、均值滤波和维纳滤波等常用的滤波方法相比较,还比较了SVM各种核函数对不同噪声的滤波效果和分析了不同阶数的Multinomial核的滤波效果。实验结果表明了ε-支持向量回归机能够有效地去除噪声,不但信噪比较高而且比较清晰,同时具有良好的稀疏性。     

PBX传爆药撞击感度影响因素的研究

为满足耐撞击用高能钝感传爆药,设计了以HMX和NTO为主体炸药,以含能聚合物1#和2#为粘结剂的传爆药配方,利用50%特性落高法对PBX传爆药的撞击感度进行了试验研究,分析了传爆药配方撞击感度的钝感机理和影响因素.     

激光棒位置对热不灵敏腔运行特性的影响

对于给定的腔型,为获得最大的稳定激光输出,必须选择最佳的激光棒位置。运用激光谐振腔的矩阵理论,给出了内含热透镜的三种腔型下的g参数以及棒位置对运行特性的影响,使用Matlab软件分别进行了理论模拟,在泵浦电压1000V、重频10Hz、晶体对称置于腔中间的条件下,通过实验验证了部分理论结论．对谐振腔的设计具有一定的指导作用。     

Design of highly efficient polarization beam splitter based on self-collimation on Si platform

A highly efficient polarization beam splitter based on self-collimation phenomenon in 2D square array of air holes in Si background is presented. For the presented structural parameters, a broad bandwidth of Δω/ω_c = 1.3% for the incidence angle of |θ_in| < 80° is obtained. Here, a maximum deviation angle of |θ_p|_max < 5° from ideal self-collimation is considered. The extinction ratios for TE and TM polarizations exceed 70 and 12 dB, respectively, in the whole frequency range through applying optimized anti-reflections at input and output ports. Structural simplicity and its compatibility with existing fabrication technologies along with the flexibility of the design to match for desired central frequency in IR range using scalability rule of Maxwell equations are outstanding features of the design.     

安全弹药的发展思路与技术途径

武器弹药的安全问题十分重要,关乎装备的生存力和战斗力。弹药面对的复杂恶劣环境,对弹药安全性提出更高要求,发展安全弹药是必由之路。弹药安全性主要取决于固有安全性和安全性增强技术。不敏感炸药是提高弹药固有安全性的关键途径,装药和结构增强与防护是提高弹药安全性的重要手段。为满足弹药高毁伤威力和安全性要求,需要从炸药的分子、晶体、混合体系等多尺度结构上平衡协调炸药高能量与不敏感之间的突出矛盾;装药结构、弹体弱链结构和防护增强等安全性增强技术可有效控制弹药装药意外点火和反应烈度及其演化,进一步提高弹药在异常环境及事故条件下的安全性。为此,提出了安全弹药系统设计思路与技术方法：加强不敏感炸药多尺度材料设计与性能调控基础,补齐装药结构与防护增强及装药异外点火反应控制短板,探索发展材料—结构—功能一体化设计。