超长、超大基坑开挖对邻近地铁结构安全影响的数值模拟分析

为了研究超长、超大基坑开挖对邻近地铁结构安全影响,以西安地铁2号线周边某基坑为工程实例,通过运用数值分析软件,结合场地的水文地质和工程地质条件,建立数值模型,进行施工过程的动态模拟,同时进行现场监测,经对比数值模拟结果及监测数据,表明运用PLAXIS软件能有效的模拟基坑开挖过程中的土体变形。同时工程采用的分段、分块开挖,中心岛顺做,周边预留土台反压、使用旋喷锚索的支护方案,对复杂条件下基坑开挖对邻近地铁结构的变形影响能起到有效的控制作用,可对类似工程的设计优化提供有益的参考及借鉴。     

Discovering social structures of local influence by using tweetStimuli

Information diffusion in large-scale networks has been studied to identify the users influence. The influence has been targeted as a key feature either to reach large populations or influencing public opinion. Through the use of micro-blogs, such as Twitter, global influencers have been identified and ranked based on message propagation (retweets). In this paper, a new application is presented, which allows to find first and classify then the local influence on Twitter: who have influenced you and who have been influenced by you. Until now, social structures of tweets’ original authors that have been either retweeted or marked as favourites are unobservable. Throughout this application, these structures can be discovered and they reveal the existence of communities formed by users of similar profile (that are connected among them) interrelated with other similar profile users’ communities.     

Group‐in‐a‐Box Meta‐Layouts for Topological Clusters and Attribute‐Based Groups: Space‐Efficient Visualizations of Network Communities and Their Ties

An important part of network analysis is understanding community structures like topological clusters and attribute‐based groups. Standard approaches for showing communities using colour, shape, rectangular bounding boxes, convex hulls or force‐directed layout algorithms remain valuable, however our Group‐in‐a‐Box meta‐layouts add a fresh strategy for presenting community membership, internal structure and inter‐cluster relationships. This paper extends the basic Group‐in‐a‐Box meta‐layout, which uses a Treemap substrate of rectangular regions whose size is proportional to community size. When there are numerous inter‐community relationships, the proposed extensions help users view them more clearly: (1) the Croissant–Doughnut meta‐layout applies empirically determined rules for box arrangement to improve space utilization while still showing inter‐community relationships, and (2) the Force‐Directed layout arranges community boxes based on their aggregate ties at the cost of additional space. Our free and open source reference implementation in NodeXL includes heuristics to choose what we have found to be the preferable Group‐in‐a‐Box meta‐layout to show networks with varying numbers or sizes of communities. Case study examples, a pilot comparative user preference study (nine participants), and a readability measure‐based evaluation of 309 Twitter networks demonstrate the utility of the proposed meta‐layouts.     

关于中压电缆网双环接线方式供电能力的分析

结合北京地区现阶段对相关技术的规定,以实际供用电方案为例,对中压电缆网双环接线方式的供电能力进行深入讨论。通过设计环网单元划分,发现某些条件下双环网供电能力可以得到进一步提升。     

抗地震结构的服役费用函数及其建立方法

讨论了服役工程结构的经济性问题 ,包括 :抗地震结构在服役过程中为完成预定功能所需要的经济花费、这些花费同结构抗震可靠度的函数关系以及它们的建立方法。形成的服役费用函数可以作为决策结构最佳抗震设防标准的依据。     

基于 OptiSystem 的海光缆链路传输性能仿真研究*

针对海光缆信息网络传输特性,采用OptiSystem软件建立了海光缆系统链路仿真模型,针对光纤中继段间距不同对链路传输性能影响进行了仿真分析,得出不同传输距离条件下误码率曲线,验证结果可为海缆通信系统工程的施工与设计提供理论依据。     

直流电桥法测量电缆故障点的距离

迅速、准确地探测故障点的位置对保证故障电缆的及时修复有着重要意义。介绍了电缆故障的性质和直流电桥法测量电缆故障点距离的原理，着重阐述了几种常用的电缆接地故障的测量方法，并提出在实际生产、施工中，应根据具体情况选取合理的仪器及测量方法，迅速、准确地探测故障点的位置，以保证故障电缆的及时修复。     

Relationships Between the Crystal Structures and the Multiple Melting Behaviors of Poly(ethylene 2,6‐naphthalate)

Summary: Poly(ethylene 2,6‐naphthalate) (PEN) can crystallize either from the glassy state or from the melt state. When crystallized from the glassy state, the sample was quenched from the melt in liquid nitrogen and then annealed at certain crystallization temperatures. When crystallized from the melt state, the sample was cooled to a preset temperature from the melt and then annealed for a certain time. The crystal modifications, morphologies and melting behaviors of PEN were investigated by means of wide‐angle X‐ray diffraction (WAXD), polarized optical microscopy (POM), small‐angle light scattering (SALS) and differential scanning calorimetry (DSC). The results show that an α crystal modification of PEN was obtained when PEN crystallized from the glassy state, whilst a β crystal modification was obtained when PEN crystallized from the melt state at a higher temperature. An hedritic morphology of PEN crystal was obtained with only one melting peak observed in DSC curves when PEN was crystallized at a higher temperature from either the glassy state or the melt state. The α crystal modification could also be obtained when PEN was crystallized at a lower temperature from the melt. Spherulitic or banded spherulitic morphologies of PEN crystals, exhibiting multiple melting peaks in DSC curves, were observed when PEN was crystallized at a lower temperature. The multiple melting behaviors of PEN crystals may be associated with spherulitic structures composed of lamellae of varying thickness.

WAXD patterns of PEN isothermally crystallized from different states.