在备件招标采购中运用"定质比价法"初探

针对公司在备件采购中存在的质量、价格等问题，探讨了如何使用“定质比价法”这一新的招标采购方法来提高备件质量、降低成本。     

A globally convergent algorithm for transportation continuous network design problem

The continuous network design problem (CNDP) is characterized by a bilevel programming model, in which the upper level problem is generally to minimize the total system cost under limited expenditure, while at the lower level the network users make choices with regard to route conditions following the user equilibrium principle. In this paper, the bilevel programming model for CNDP is transformed into a single level convex programming problem by virtue of an optimal-value function tool and the relationship between System Optimum (SO) and User Equilibrium (UE). By exploring the inherent nature of the CNDP, the optimal-value function for the lower level user equilibrium problem is proved to be continuously differentiable and its derivative in link capacity enhancement can be obtained efficiently by implementing user equilibrium assignment subroutine. However, the reaction (or response) function between the upper and lower level problem is implicit and its gradient is difficult to obtain. Although, here we approximately express the gradient with the difference concept at each iteration, based on the method of successive averages (MSA), we propose a globally convergent algorithm to solve the single level convex programming problem. Comparing with widely used heuristic algorithms, such as sensitivity analysis based (SAB) method, the proposed algorithm needs not strong hypothesis conditions and complex computation for the inverse matrix. Finally, a numerical example is presented to compare the proposed method with some existing algorithms.     

重油催化裂化沉降器结焦原因分析

分析了重油催化裂化沉降器结焦的原因，认为反应油气中含有催化剂颗粒以及油气中重组分的冷凝是沉降器结焦的物理原因，而重芳烃、胶质、沥青质的高温缩合则是沉降器结焦的化学因素。因此，防止沉降器结焦的关键是抑制油气重组分的冷凝和减少油气在沉降器内的停留时间。     

Piezoelectric Nanogenerators for Self-Powered Nanodevices

A novel approach converts nanoscale mechanical energy into electric energy for self-powering nanodevices.In our own work, we've used piezoelectric zinc-oxide nanowire (ZnO NW) arrays to demonstrate a novel approach for converting nanoscale mechanical energy into electric energy. Here, we review the fundamental principle behind the nanogenerator, present an approach for improving its performance, and discuss some of the challenges we face in pushing this technology to reach its potential.     

浅谈浸出油厂厂区消防设计

浸出油厂的厂区消防安全是保证企业正常生产的关键.本文对浸出油厂厂区总平面布置、防火间距、消防通道及消防设施等几个方面作了系统阐述.     

GPS定位精度的提高及其应用

本文简明介绍了美国全球定位系统(GPS)的工作原理和误差来源,通过了解误差来源阐述了较准准确的定位技术DGPS的原理和应用。     

Thermokinetics of Liquid-Liquid Reaction of Dy（NO3 ）3 with Histidine

The thermokinetics of liquid-liquid reaction of dysprosium nitrate with histidine were studied using a microcalorimeter. On the basis of experimental and calculated results, threethermodynamic parameters (the activation enthalpy, the activation entropy and the activation free enegy),the rate constant, three kinetic parameters (the activation energy, the pre-exponential constant and the reaction order) wereobtained. On the basis of thermodynamics and kinetics, the for marion reaction of the complex was discussed.     

无氢类金刚石碳膜的研究进展

介绍了无氢类金刚石碳膜的制备方法 ,它们的机械、光学、电学性能 ,将无氢与含氢的类金刚石碳膜进行了简单比较 ,总结及探讨了它们的应用     

电话防盗报警器

详细介绍了电话通讯技术以及安全报警技术的应用，二者如何有效地结合起来形成综合联网报警系统。分析了HT9200A和MT8870DC的电路结构，及与AT89C51的接口电路。