用理想平面应变试件直接测定延性材料K_(IC)方法的研究

推荐三种理想平面应变试件,介绍了用这三种试件直接测定延性材料K_(IC)方法.     

关于DDE特征函数的反函数

本文讨论与一类ＮＤＤＥ有关的超越特征的函数ｙ＝Ｓ（ｅ~Ｓ＋Ａ）的反函数的性质，当Ｓ∈Ｒ时，可用这些性质建立ＮＤＤＥ振动性的新判别法。     

借鉴影响因子用于科研人员和科研机构绩效评估

随着国家对科学研究投入的不断增加，社会和公众对科学研究的绩效越来越关注。如何对科学研究的绩效进行有效评估是科研管理的一个重要方面。同行评议的定性评估虽然得到越来越多的重视，但其依赖主观判断的本质使其客观公正性得不到根本保障，在定性评估中引入合理的定量评价指标是一种可行的途径。发表研究论文数量、被引用总次数、发表期刊影响因子之和等单指标因子已被用于绩效评估。但由于单指标的片面性以及使用的过度化，产生了很大的负面影响。     

Paleomagnetic dating of the topmost terrace in Kouma,Henan and its indication to the Yellow River＇s running through Sanmen Gorges

In the east of Xiaolangdi, many river terraces are developed at the exit of the Yellow River Gorges. Among them the terraces in Kouma, Yanshi of Henan Province are most typical, where the Yellow River developed three staircase terraces, among which the altitude of gravel stratum of the topmost terrace is 30-35 m higher than the river level.The top of the gravel stratum was covered by 60 m eolian loess deposits which have many brownish-red paleosol strips.And the paleosol $14 is at its bottom. Research on systematic magnetostratigraphy and paleosol-loess matching indicates that the bottom age of the loess on the topmost terrace is 1165 ka. Therefore, it can be concluded that the terrace develops no later than 1.165 Ma and the situation that the Yellow River runs through Sanmen Gorges and inpours into East China Sea happened at least before 1.165 Ma.     

Dating and genesis of the upper Weihe River terraces in Longxi basin, China

Seven terraces along the Weihe River in Longxi basin have been investigated. These terraces all consist of archetypal duality in structure, namely the floodplain deposits and the layer of gravels overlaid by varying thickness of the loess. By resorting to various dating approaches such as palaeomagnetic, optically stimulated luminescenece (OSL), 14C and loess-paleosol sequence, we provide preliminary timing of these seven terraces along upper Weihe River. Analysis on sedimentation characteristics and dating of these terraces showed that seven terraces may be jointly generated by tectonic uplifts and climatic changes. Tectonic uplifts may accommodate initial river incision, and climatic change may be responsible for processes of subsequent channel widening and aggradation. Aggradation normally occurs during glacial periods, in contrast to down-cuttings during transitions from glacial to interglacial period. Moreover, on the basis of the timings and heights of these terraces, we infer that the long-term rate of river incision was determined to be 0.2 m/kyr during the last 870 kyr, which differs from other river incision rates. This discrepancy may reflect spatio-temporal differentiation of tectonic activities in the Qinling orogenic belt during the Pleistocene.     

不确定型AHP的最优传递矩阵法

给同区间判断矩阵的最优传递矩阵，并以此确定其权重区间，应用区间判断矩阵给出群体判断一种方法。     

Effective method for tracking multiple objects in real-time visual surveillance systems

An object model-based tracking method is useful for tracking multiple objects, but the main difficulties are modeling objects reliably and tracking objects via models in successive frames. An effective tracking method using the object models is proposed to track multiple objects in a real-time visual surveillance system. Firstly, for detecting objects, an adaptive kernel density estimation method is utilized, which uses an adaptive bandwidth and features combining colour and gradient. Secondly, some models of objects are built for describing motion, shape and colour features. Then, a matching matrix is formed to analyze tracking situations. If objects are tracked under occlusions, the optimal “visual” object is found to represent the occluded object, and the posterior probability of pixel is used to determine which pixel is utilized for updating object models. Extensive experiments show that this method improves the accuracy and validity of tracking objects even under occlusions and is used in real-time visual surveillance systems.     

2007年中国大陆科研机构在PNAS发表论文统计

PNAS（Proceedings of the National Academy of Sciences of the United States of America,《美国科学院院刊》）是一份国际高水平的综合性科技期刊,在PNAS上发表论文情况从一个侧面反映了一个国家科技特别是基础研究的水平。本文对我国科研机构（不包括香港、澳门和台湾地区的科研机构）2007年在PNAS上发表的研究论文进行了简单的统计分析,以期能够对我国科研机构在国际高水平期刊发表论文情况有一个概括性的认识。本文统计的论文仅是研究性论文,不包括对已发表文章的置疑、评论、回应及其它文献类型。     

高温高压下钻井液循环流动摩阻实验研究

深层油气勘探开发过程中常面临高温高压的挑战,钻井液在高温高压等复杂工况下,其性能会发生改变,研究钻井液在复杂工况下的流动摩阻变化规律,能为特深井钻井提速及井控提供理论基础。根据实际工况要求,建立了高温高压钻井液循环流动摩阻测试装置,实验研究了温度、压力、固相颗粒及含气率对钻井液流动摩阻的影响,采用多元回归方法拟合并绘制温压摩阻系数图版,能更好阐述温压与钻井液流动摩阻的定量关系。结果表明：顺北区块钻井液流动摩阻随温度增大而减小,随压力增大而增大,摩阻系数图版能更准确体现摩阻系数与温压的定量关系,固体颗粒含量对流动摩阻影响不大,钻井液流动摩阻随着含气率增加而增大。该实验装置与分析方法,对于研究复杂工况下钻井液流动摩阻变化规律具有重要意义。     

基于Tent映射NSGA-II算法的微电网多目标优化方法

为提高微电网运行的经济性、降低网络中的碳排放量和有功功率损耗,文中提出一种基于Tent混沌映射NSGA-II算法的微电网能量优化管理方法。该方法采用双层能量优化管理：上层采用模糊管理系统确定微电网运行模式,下层采用改进NSGA-II算法对能量进行优化管理。首先在多约束条件下,建立以微电网运行经济性、网络中碳排放量和有功功率损耗为目标函数的多目标优化数学模型。其次在多目标优化数学模型求解过程中,引入Tent混沌映射方法来增加NSGA-II算法的种群多样性,以提高算法的全局搜索能力,同时利用隶属度函数确定微电网能量优化管理策略。最后运用欧洲一典型微电网作为算例,验证所提出的能量管理方法、容量配置优化模型以及改进NSGA-II算法的合理性和有效性。仿真结果表明：改进NSGA-II算法具有良好的优化效果,使得微电网运行的经济性得到了显著提升,较传统算法提高了14.55%;碳排放量有所降低,较传统算法减小了3.10%,可实现对微电网多目标的优化。