Atomic packing and short-to-medium range order evolution of Zr-Pd metallic glass

A larger-scale Zr₇₀Pd₃₀ alloy system has been simulated using molecular dynamics (MD) to investigate structure evolution in Zr₇₀Pd₃₀ metallic glass. The simulated pair distribution function of Zr₇₀Pd₃₀ metallic glass agrees well with the experimental results. Voronoi polyhedron analysis indicates that the icosahedra are not randomly distributed in space, but form characteristic intercrossed icosahedral clusters with medium-range order. Intercrossed icosahedral clusters are the dominant local configurations in Zr₇₀Pd₃₀ metallic glass and probably cause the quasicrystalline phase discovered in Zr₇₀Pd₃₀ metallic glass.     

欧阳修的台阁名胜记略论

欧阳修是北宋著名的文学家，其多方面的文学成就，在中国古代文学史上占有重要的地位。本文通过对欧阳修台阁名胜记文的分析，探讨它们的分类、特征及其重要地位，并在此基础上进一步研究其对苏轼等人的影响。     

Effect of Ag addition on the thermal stability and glass-forming ability of Zr<Subscript>35</Subscript>Ti<Subscript>30</Subscript>Cu<Subscript>7.5</Subscript>Be<Subscript>27.5</Subscript> bulk metallic glass

The thermal stability and glass forming ability (GFA) of Zr35-xTi30Cu7.5Be27.5Agx (x = 0-10) alloys were studied by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and ultrasonic techniques. We found that the addition of 1 at.% Ag can considerably enhance the GFA as indicated by an increase in the critical glass dimension from 15 mm in the Zr35Ti30Cu7.5Be27.5 alloy to 20 mm in the Zr34Ti30Cu7.5Be27.5Ag1 alloy. However, with the addition of more Ag the supercooled liquid region (△Tx) and y parameter (defined as Tx/(Tg+Tl)) drastically decreased from 155 K and 0.436 to 76 K and 0.363, respectively, resulting in a decrease in the GFA. Additionally, the elastic constant (the ratio of shear modulus to bulk modulus or Poisson’s ratio) was also used as a gauge to evaluate the GFA in Zr35-xTi30Cu7.5Be27.5Agx alloys.     

硬聚氯乙烯三通管挤胀成型的有限元模拟及优化

采用Ansys^®通用分析软件对硬聚氯乙烯(UPVC)三通管的挤胀成型过程进行了有限元模拟和优化。通过模拟获得了三通管挤胀成型过程中的主要失效形式。采用单步循环法模拟了不同过渡圆角情况下三通管的成型过程,确定了合理的设计域,在此基础上分别采用子问题逼近法和一阶优化法获得了对于不同过渡圆角情况下三通管优化的设计参数组合。在模拟和优化的基础上,利用自行设计的实验台成功地实现了UPVC三通管的挤胀成型。实验和模拟研究结果表明,挤胀成型方法对于一些特定类型制品的成型是可行的。     

Biogeographical patterns of the diet of Palearctic badger:Is badger an earthworm specialist predator?

Badgers were hypothesized as an earthworm specialist predator.We reviewed spatial patterns and food habits of the Eurasian badger(Meles spp.) in relation to geographical variables like latitude,elevation,aspects,and environmental variables,such as temperature,snow cover depth,precipitation,primary productivity,and human influence.The relative frequencies of occurrence of food items in the diets of badgers in 19 studies across 22 localities worldwide were included in the analysis plus the data from our study on the badger diet on the Qinghai-Tibetan Plateau.Principal component analysis(PCA) was used to extract the main components of dietary composition.Multiple regression analysis was applied to reveal the relationship between trophic diversity and the main PCA factors and biogeographical variables.We found a clear latitudinal gradient in the dietary composition of badgers,which was characterized by a greater consumption of insects and reptile in southern area and a higher intake of earthworm in northern regions.Nevertheless,badgers are not an earthworm specialist predator.Furthermore,trophic diversity of badger diets was significantly positively correlated with latitude and human activity.Abundance and availability of foods appear to determine badger foraging tactics.Badgers are adept in exploiting local resources and our results confirm that badgers are generalist predators with opportunistic foraging behavior across their entire distribution range.     

采用金属梯度材料优化机械零件设计

论述了采用金属梯度性能材料优化拉杆类、压杆类、简支梁类、凸模类机械零件设计问题。将上述零件设计成材料的组织、性能沿零件长度方向呈梯度分布状态，可改变过载时失效发生的部位，不导致零件相关组件损坏，可提高零件工作安全性、可靠性。     

Uprising period and elevation of the Wenyu granitic pluton in the Xiaoqinling District, Central China

Xiaoqinling District is an important gold-producing area in China. It ranks second to Jiaodong with regard to gold deposits. The uprising period of the Wenyu granitic pluton and the wall-rocks of the deposit, as well as the mineralizing depth and reserved place of gold ore bodies, are significant to ore exploration. Fission-track （FT） analysis of zircons and apatites of granitic rocks from the Wenyu granitic pluton shows that apatite FT （AFT） data modeling indicates a rapid cooling rate of 20℃/Ma from 138 to 120 Ma after emplacement at 138 Ma. Thermal evolution and inversion curves suggest a secondary phase of fast cooling and up- rising from 45 to 35 Ma, and 35 Ma, respectively, with a cooling rate of 6.7℃/Ma and a denudation quantity of -4.3 km. The last cooling phase took place from 〈4 Ma, with an average cooling rate of -11.3℃/Ma and a denudation amount of 1.3 km. Total exhumation quantity of 5.6 km and uprising elevation of 7.3 km are similar to the estimated results of fluid inclusions from the Dongtongyu and Wenyu gold deposits. The 39Ar/40Ar dating of sericite from the fault planes of the Xunmadao-Xiaohe and Taiyao faults demonstrate two uprising activities of the ore-host metamorphic complex. The Huashan and Wenyu granitic plutons inten- sively occurred during 77 and 45 Ma, respectively. These data sets are valuable for understanding the uplifting process and for preserving gold ore bodies in the Xiaoqinling area, as well as for further studies on tectonic evolutions of the Taihua Complex and the Qinling-Dabie Orogen.     

截齿齿座焊接裂纹模拟试验

对３０ＣｒＭｎＳｉ钢、Ａ３钢进行模拟焊接试验,观察分析了接头组织变化,对焊接冷裂纹产生的组织因素进行了分析,并对生产中制定焊接工艺规范提出意见。     

基于用户标签的社区发现方法研究

为充分挖掘标签中潜在的用户信息、提供更好的个性化服务,在分析用户标签使用情况的基础上,提出一种面向用户的社区发现方法。综合考虑标签使用频率和稀疏度,并同时使用二者构造一个邻接矩阵进行聚类,最终完成社区发现,并且论证了该方法的可行性。     

An environmental database and temporal and spatial distribution of Chinese paleoanthropological sites

A comprehensive database of paleoenvironmental settings for paleoanthropological sites provides a useful tool to explore the link between human evolution and paleoenvironmental changes. A preliminary GIS-based environmental database for paleoanthropological sites in China (EDPC) was constructed based on data collected from published literature. The database currently contains 1114 paleoanthropological sites. It will be available for online access following the establishment of relevant rules, and after impr...