Dieless drawing steel wires using a dielectric heating method and modeling the process dynamics

Modern industries require the production of multi-functional, inorganic, micron-sized metal wires. This study suggests a novel method that could potentially offer a highly efficient dieless drawing technology for manufacturing thin stainless steel fibers. The method is based on a hot-working principle, using microwaves as the heat source and SiC as the susceptor. Experimental trials with a laboratory rig showed that the new system worked effectively for drawing the stainless steel wires and should be able to realize the diameter attenuation with a diameter reduction of up to 21%. The theoretical model describing the deformation behavior of the stainless steel wires in the working zone along with the constitutive equation of Bingham model modified with a power law and Zener–Hollomon parameter turned out to match very good with the actual results of the experiment. The coefficient of variation of the drawn wire diameter increased, as the draw ratio increased, which could be attributed to the occurrence of the narrow necking zone.     

钢筋混凝土阴极保护极化曲线实时测试仪器设计

阴极保护是应用于钢筋混凝土腐蚀防护的一种有效技术,测试其阴极极化曲线对于防腐系统参数设计具有重要的指导意义。本文设计了一种极化曲线测试仪器,该仪器通过嵌入式系统控制强制电流阴极保护系统的激励电流,采集阴极保护系统由此产生的电位变化,测试的数据由嵌入式系统暂存并通过无线通信接口传输到监控中心计算机,监控计算机存储并分析保护行的极化曲线。试验结果表明该仪器能自动、实时地测试阴极保护系统的极化曲线,为检测被保护结构物的保护状态提供数据支持。     

不成橇设计中仪表施工图的制作及应用

在海洋石油平台不成橇设计中,对于一些非工艺的无管线号的管线,在ISO图中均不能很好地体现出来,由此在施工申产生了一系列问题。文章介绍一种利用AutoCAD软件和EXCEL 表格绘制施工图的模板,采用此模板绘制仪表施工图,对仪表管线等无管线号管线的施工及料单的统计起到了促进作用。用该模板制作的施工图,简单明了,具有较好的三维真实感,可提高施工人员的读图速度。便于安装和维修。     

试论交换工程档案管理

工程档案管理工作是使工程文件材料向峡工档案转化的基础工作，是向档案馆提供馆藏，进行科技贮备的重要环节，也是工程管理的重要组成部分。本文介绍了交换工程档案管理的特点并就如何进行此项管理发表了个人见解。     

审图阶段工程设计档案的管理

施工图审核既是工程开工前专业人员必须完成的一项重要技术前期工作,也是开展设计交底,图纸会审的基础,又是施工方编制施工组织设计的重要依据,更是日后体现该项目技术管理质量好坏的效果之一。严格执行施工图审查制度,在图纸交付施工之前发现设计问题可以将风险降到最低。执行施工图审查制度,对工程设计档案管理提出新的要求。针对工程设计档案管理新要求,制定相应管理制度;并对当前施工图审查阶段工程设计档案管理存在的问题及原因进行阐述,提出了相关建议。     

电力工程计算机辅助制图专用软件的研究

本文研究了利用AUTOCAD软件开发电力工程电路微型计算机辅助制图专用软件的有关问题,主要有图形符号库的建立及屏幕菜单的编制等,并给出了绘图实例。电力工程电路图用微型计算机辅助制图有绘图迅速,图形清晰、美观,并符合国家标准等优点。     

枯水径流若干问题研究进展

着重对枯水径流频率分析、流量历时曲线、基流分割及退水分析等进行了阐述，分析了枯水径流特征与流域地形、地貌、水文地质特性和土地利用等空间信息之间的相关关系，并对无资料地区的枯水径流预测进行了探讨。     

On Curvatures and Focal Points of Distributions of Dynamical Lagrangian Distributions and their Reductions by First Integrals

Pairs (Hamiltonian system, Lagrangian distribution) called dynamical Lagrangian distributions, appear naturally in differential geometry, calculus of variations, and rational mechanics. The basic differential invariants of a dynamical Lagrangian distribution with respect to the action of the group of symplectomorphisms of the ambient symplectic manifold are the curvature operator and curvature form. These invariants can be considered as generalizations of the classical curvature tensor in Riemannian geometry. In particular, in terms of these invariants one can localize the focal points along extremals of the corresponding variational problems. In the present paper we study the behavior of the curvature operator, the curvature form, and the focal points of a dynamical Lagrangian distribution after its reduction by arbitrary first integrals in involution. An interesting phenomenon is that the curvature form of so-called monotone increasing Lagrangian dynamical distributions, which appear naturally in mechanical systems, does not decrease after reduction. It also turns out that the set of focal points to the given point with respect to the monotone increasing dynamical Lagrangian distribution and the corresponding set of focal points with respect to its reduction by one integral are alternating sets on the corresponding integral curve of the Hamiltonian system of the considered dynamical distributions. Moreover, the first focal point corresponding to the reduced Lagrangian distribution comes before any focal point related to the original dynamical distribution. We illustrate our results on the classical N-body problem. 2000 Mathematics Subject Classification. 37J15, 37J05, 53D20.     

Deterministic Time-Varying Packet Fair Queueing for Integrated Services Networks

In integrated services networks, the provision of Quality of Service (QoS) guarantees depends critically upon the scheduling algorithm employed at the network layer. In this work we review fundamental results on scheduling, and we focus on Packet Fair Queueing (PFQ) algorithms, which have been proposed for QoS wireline-wireless networking. The basic notion in PFQ is that the bandwidth allocated to a session is proportional to a positive weight _i . Because of the fixed weight assignment, the inherent in PFQ delay-bandwidth coupling imposes limitations on the range of QoS that can be supported. We develop PFQ with deterministic time-varying weight assignments, and we propose a low-overhead algorithm capable of supporting arbitrary piecewise linear service curves which achieve delay-bandwidth decoupling. Unlike existing service-curve based algorithms, our time-varying PFQ scheme does not exhibit the punishment phenomenon, and allows sessions to exploit the extra bandwidth in under-loaded networks.     

适用于计算机绘图的数据结构浅议

计算机绘图中的数据处理,图学者往往感到棘手。本文介绍一种方便可行的数据结构,并举例说明其应用。