随机智能桁架结构闭环控制平稳随机响应分析

研究平稳随机激励下随机智能桁架结构的闭环动力响应问题。同时考虑智能桁架结构的物理参数、几何尺寸和阻尼的随机性，利用矩法和代数综合法，从结构平稳随机响应在频域上的表达式出发，分别导出随机智能桁架结构在平稳随机激励下闭环位移响应均方值和应力响应均方值的均值、方差的计算表达式。通过算例考察结构物理参数、几何尺寸和阻尼的随机性对结构位移响应均方值与应力响应均方值随机变量随机性的影响，并获得若干有意义的结论。     

随机参数刚架结构的平稳随机位移响应动力可靠性分析

研究物理参数具有随机性的刚架结构的平稳随机位移响应动力可靠性的计算方法。考虑结构的物理参数具有随机性，从结构随机响应的频域表达式出发，利用求解随机变量数字特征的代数综合法和矩法，导出随机参数刚架结构在平稳随机激励下的位移及速度响应均方值的数字特征，再由动力可靠性的Poisson公式导出结构动力可靠度的计算公式。通过算例就各参数的随机性对结构动力可靠度的影响进行分析，验证本文方法的可行性。     

水力压裂的连续损伤模型初探

水力压裂是油气藏改造中最常用的工程措施,通过数值模拟研究水力压裂过程具有十分重要的意义.将Gurson损伤模型引入水力压裂分析中,建立水力压裂的损伤力学模型.通过数值计算分析水力压裂对多孔介质的损伤效果,并探讨用损伤理论研究油藏水力压裂的基本思路.     

An in-depth investigation into the relationships between structural metrics and unit testability in object-oriented systems

There is a common belief that structural properties of classes are important factors to determine their unit testability.However,few empirical studies have been conducted to examine the actual impact of structural properties of classes.In this paper,we employ multiple linear regression(MLR) and partial least square regression(PLSR) to investigate the relationships between the metrics measuring structural properties and unit testability of a class.The investigated structural metrics cover five property dimensions,including size,cohesion,coupling,inheritance,and complexity.Our results from open-source software systems show that:(1) most structural metrics are statistically related to unit testability in an expected direction,among which size,complexity,and coupling metrics are the most important predictors;that(2) multivariate regression models based on structural metrics cannot accurately predict unit testability of classes,although they are better able to rank unit testability of classes;that(3) the transition from MLR to PLSR could significantly improve the ability to rank unit testability of classes but cannot improve the ability to predict the unit testing effort of classes.     

In situ incorporation of monodisperse drug nanoparticles into hydrogel scaffolds for hydrophobic drug release

The effective and locally sustained delivery of hydrophobic drug with hydrogels as carriers is still a challenge owing to the inherent incompatibility of hydrophilic hydrogel network and hydrophobic drug. One promising approach is to use porous hydrogels to encapsulate and deliver hydrophobic drug in the form of nanoparticles to the disease sites. However, this approach is currently limited by the inability to load concentrated hydrophobic drug nanoparticles into the hydrogels because of the severe nanoparticle aggregation during the loading process. In this article, we firstly designed and fabricated efficient drug nanoparticles embedded hydrogels for hydrophobic drug delivery by incorporating monodisperse silybin (hydrophobic drug for liver protection) nanoparticles into acrylated hyaluronic acid (HA‐AC) based hydrogels through in situ cross‐linking. The silybin nanoparticles embedded hydrogel scaffolds proved to be a good sustained release system with a long period of 36 h. The drug release from this hybrid hydrogels could be modulated by tuning HA‐AC concentration, cross‐linking ratio, chain length of cross‐linker and drug loading amount. The different kinetic models were applied, and it was observed that the release profile of silybin best followed the Hixson‐Crowell model for the release of drug from the hydrogels embedding silybin nanoparticles. It could be envisioned that this process would significantly advance the potential applications of hydrogel scaffolds mediated hydrophobic drug delivery in clinical therapies. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43111.     

CBERS-02IRMSS热红外数据及UTAE算法在城市热岛研究中的应用

文中使用城市热异常信息提取算法(urban thermal anomaly extraction,UTAE)提取城市热岛信息.该算法使用不同大小的滑动窗口来探测整幅图像,根据稳健估计的方法设定地表温度高于全部像元以及窗口内像元温度统计均值加标准差的像元为热异常像元,并将滑动窗口的范围设置在3×3至9×9个像元之间,根据像元被记为热岛像元的次数是否为0来区别热岛区与非热岛区,在热岛区域内根据次数的多少来决定热岛强度,具有动态阈值的特点和无偏特性.研究结果表明,在城市热岛范围的提取上,2004年2月13日长沙市热岛面积在27.21—33.98km2之间;在城市热岛强度和尺度效应分析上,宏观尺度的研究应选用较大的窗口来体现城—郊热岛关系以及热岛发展的总体趋势,而小窗口在微观分析城区内热岛的具体分布、与下垫面的关系以及驱动因子方面较有优势.最后,对UTAE算法在中巴地球资源卫星后继星数据上的应用做出了展望.     

Attribute reduction theory of concept lattice based on decision formal contexts

The theory of concept lattices is an efficient tool for knowledge representation and knowledge discovery, and is applied to many fields successfully. One focus of knowledge discovery is knowledge reduction. Based on the reduction theory of classical formal context, this paper proposes the definition of decision formal context and its reduction theory, which extends the reduction theory of concept lattices. In this paper, strong consistence and weak consistence of decision formal context are defined respectively. For strongly consistent decision formal context, the judgment theorems of consistent sets are examined, and approaches to reduction are given. For weakly consistent decision formal context, implication mapping is defined, and its reduction is studied. Finally, the relation between reducts of weakly consistent decision formal context and reducts of implication mapping is discussed.     

无内胎轮胎11L-15质量缺陷分析及解决措施

近年来,随着国内、国际农用机械的发展,对无内胎轮胎的需求量逐渐增大。在11L-15无内胎轮胎用46″硫化机生产时易出现胎体变形、钢丝圈上抽等质量缺陷。本文分析了11L-15无内胎轮胎质量缺陷产生的原因,并提出解决措施。