Experimental research on a modular miniaturization nanoindentation device

Nanoindentation technology is developing toward the in situ test which requires miniaturization of indentation instruments. This paper presents a miniaturization nanoindentation device based on the modular idea. It mainly consists of macro-adjusting mechanism, x-y precise positioning platform, z axis precise driving unit, and the load-depth measuring unit. The device can be assembled with different forms and has minimum dimensions of 200 mm × 135 mm × 200 mm. The load resolution is about 0.1 mN and the displacement resolution is about 10 nm. A new calibration method named the reference-mapping method is proposed to calibrate the developed device. Output performance tests and indentation experiments indicate the feasibility of the developed device and calibration method. This paper gives an example that combining piezoelectric actuators with flexure hinge to realize nanoindentation tests. Integrating a smaller displacement sensor, a more compact nanoindentation device can be designed in the future.     

全方位超声波扫描器的设计

采用步进电机带动超声波传感器对障碍物进行扫描．并对障碍物距离进行测量，这便是本全方位超声波扫描器的基本原理。基于上述原理，本文论述了一种全方位超声波扫描器的设计．同时给出了系统的各模块的设计。     

余热排出系统管道热疲劳分析模型及寿命预测

余热排出系统管道发现的热疲劳裂纹问题关系到压水堆的安全。本文基于开源有限元软件Code_Aster,采用Lagoda-Macha-Sakane模型预测了余热排出系统管道材料304L不锈钢的疲劳寿命,并根据预测结果提出了改进的Lagoda-Macha-Sakane模型。采用改进的Lagoda-Macha-Sakane模型对余热排出系统管道的热疲劳寿命进行了预测,结果表明预测热疲劳寿命与试验热疲劳寿命吻合。     

Analysis of gene expression programming for approximation in engineering design

To reduce the computational cost of implementing computer-based simulations and analyses in engineering design, a variety of metamodeling techniques have been developed and used for the construction of metamodels. Metamodels, also called approximation models and surrogate models, can be used to make a replacement of the expensive simulation codes for design and optimization. In this paper, gene expression programming (GEP) algorithm in the evolutionary computing area is investigated as an alternative metamodeling technique to provide the approximation of a design space. The approximation performance of GEP is tested on some low-dimensional mathematical and engineering problems. A comparative study is conducted on GEP and three common metamodeling techniques in engineering design (i.e., response surface methodology (RSM), kriging and radial basis functions (RBF)) for the approximation of the low-dimensional design space. Multiple evaluation criteria are considered in the comparison: accuracy, robustness, transparency and efficiency. Two different sample sizes are adopted: small and large. Comparative results indicate that GEP can achieve the most accurate and robust approximation of a low-dimensional design space for small sample sets. For large sample sets, GEP also presents good prediction accuracy and high robustness. Moreover, the transparency of GEP is the best since it can provide clear function relationships and factor contributions by means of compact expressions. As a novel metamodeling technique, GEP shows great promise for metamodeling applications in a low-dimensional design space, especially when only a few sample points are selected and used for training.     

独轮移动机器人被动式避障和目标跟踪控制仿真实验

为了使移动机器人能在动态环境中安全地运动并探索周围的情况,针对动态变化的环境中,传感器范围有限的一类非完整系统-独轮移动机器人,提出了一种新的被动式目标跟踪控制方法,使其能在动态变化的环境中有效地避免静止和运动的障碍物.文中在极坐标下,考虑了移动机器人和障碍物的相对运动,首次将极坐标变换与李雅普诺夫分析方法结合起来,提出一种解决独轮机器人的位置跟踪和避障问题的方便实用的被动式控制算法:更重要的是,所提出的方法考虑了运动控制的饱和约束.通过仿真实验证明了提出的独轮机器人多目标控制的李亚普洛夫设计的有效性,为进一步研究多移动机器人或具更复杂的非完整约束机器人的多目标控制奠定了基础.     

动态系统描述语言的特性、设计和实现

介绍一种新型的动态系统描述语言,PDSDL.它比SystemC更加高效和灵活.(1)PDSDL使用了Python面向对象动态语言,(2)PDSDL创新性地提出了动态系统的概念.系统的建模、验证和综合全都依赖于运行时动态系统特性,而非传统的存储在非易失记忆体(例如文件)的静态描述.因此设计者能使用程序和高级人工智能方式来进行更高效的结构探索.本文的重点在于探讨动态系统描述语言的特性和实现机理.文末给出简要试验结果.     

应用平台创建套件(PCS)进行嵌入式Linux应用的研究

文章主要主要介绍了Linux开发工具平台创建套件(PCS)的开发环境,以及应用平台创建套件(PCS)进行嵌入式Linux应用开发的过程。     

芳香族化合物的清洁催化硝化

综述了芳香族化合物清洁催化硝化体系中硝化剂和催化剂的研究近况,主要介绍了氮氧化物、硝酸和硝酸/乙酸酐三种硝化剂及相应的催化剂体系的催化硝化性能及优缺点,并进一步探讨了清洁硝化的发展前景。     

Genetic Dissection of Phosphorus Use Efficiency and Genotype-by-Environment Interaction in Maize

Genotype-by-environment interaction (G-by-E) is a common but potentially problematic phenomenon in plant breeding. In this study, we investigated the genotypic performance and two measures of plasticity on a phenotypic and genetic level by assessing 234 maize doubled haploid lines from six populations for 15 traits in seven macro-environments with a focus on varying soil phosphorus levels. It was found intergenic regions contributed the most to the variation of phenotypic linear plasticity. For 15 traits, 124 and 31 quantitative trait loci (QTL) were identified for genotypic performance and phenotypic plasticity, respectively. Further, some genes associated with phosphorus use efficiency, such as Zm00001eb117170, Zm00001eb258520, and Zm00001eb265410, encode small ubiquitin-like modifier E3 ligase were identified. By significantly testing the main effect and G-by-E effect, 38 main QTL and 17 interaction QTL were identified, respectively, in which MQTL38 contained the gene Zm00001eb374120, and its effect was related to phosphorus concentration in the soil, the lower the concentration, the greater the effect. Differences in the size and sign of the QTL effect in multiple environments could account for G-by-E. At last, the superiority of G-by-E in genomic selection was observed. In summary, our findings will provide theoretical guidance for breeding P-efficient and broadly adaptable varieties.