公路桥梁伸缩装置的若干技术问题

本文在总结国内外桥梁伸缩装置的使用经验基础上,论述了公路桥梁伸缩装置的基本性能要求、伸缩装置的主要类型、走行性能要求、设计计算规定、地震设计和性能检测等方面的内容,可供广大工程技术人员参考。     

道路工程软土地基的加固措施研究

近几年,伴随国内建筑技术的发展,软土地基处理技术同样发展迅速。当代建筑物对于软土地基进行处理时,有了更高的技术要求。在本文中,根据本人以往相关经验,探讨和分析了加固软土地基的常见方法。     

空分冷箱基础的设计要求和保温形式的选择

由于空分设备冷箱基础存在长期处于低温状态的可能,其设计具有一定的特殊性。详细叙述空分设备冷箱基础设计的基本要求,分析对冷箱基础实施保温的必要性,介绍两种保温形式及其选用。     

基于农业气象和农业种植结构的区域农业需水研究——以唐山市为例

农田需水量预测是农业灌溉需水量的关键,其合理利用与农业水资源高效利用、科学管理有极为重要作用。为合理分析区域农田需水量,本文在全面分析农田需水量计算方法的基础上提出了以区域水资源合理配置为基础,将优化作物布局,调整种植结构,和采取作物适时灌溉相结合条件下的经济灌溉需水量预测方法;并以唐山市为例,采用45年的水文气象资料对未来20年全市充分和经济灌溉条件下的农田灌溉需水定额和灌溉需水量作了预测。结果表明,唐山市2010年、2020年经济灌溉需水量较充分灌溉条件下的农田综合灌溉定额分别减少76.9mm、68.0 mm,对应的农田用水量分别下降了4.07×108m3和3.59×108m3。比较不同灌溉条件下的农业需水量变化发现在农业灌溉中采用经济灌溉方式将有利于缓减未来农业供需水不足的矛盾。     

十三陵蓄能电厂上水库自动化监测系统的设计特点及运行状况

为了能够保证十三陵抽水蓄能电厂上水库水工建筑物的安全运行，安装了DG型分布式大坝安全自动化监测系统，对所埋设的仪器电缆及系统防雷均采取了有效的措施，并取得了良好的效果，为其他采用人工监测的类似工程提供了借鉴。     

PS版和感光胶片包装用衬纸的质量要求及检测指标

本文提出了PS版和胶片包装用衬纸对纸张的质量要求,以及不同质量的衬纸可能对感光材料造成的影响;并简要介绍了纸张的基本特性;作为感光材料包装用衬纸需要进行的检测指标及检测方法。     

Are the Perspectives Really Different? – Further Experimentation on Scenario-Based Reading of Requirements

Perspective-BasedReading (PBR) is a scenario-based inspection technique whereseveral reviewers read a document from different perspectives(e.g. user, designer, tester). The reading is made accordingto a special scenario, specific for each perspective. The basicassumption behind PBR is that the perspectives find differentdefects and a combination of several perspectives detects moredefects compared to the same amount of reading with a singleperspective. This paper presents a study which analyses the differencesin perspectives. The study is a partial replication of previousstudies. It is conducted in an academic environment using graduatestudents as subjects. Each perspective applies a specific modellingtechnique: use case modelling for the user perspective, equivalencepartitioning for the tester perspective and structured analysisfor the design perspective. A total of 30 subjects were dividedinto 3 groups, giving 10 subjects per perspective. The analysisresults show that (1) there is no significant difference amongthe three perspectives in terms of defect detection rate andnumber of defects found per hour, (2) there is no significantdifference in the defect coverage of the three perspectives,and (3) a simulation study shows that 30 subjects is enough todetect relatively small perspective differences with the chosenstatistical test. The results suggest that a combination of multipleperspectives may not give higher coverage of the defects comparedto single-perspective reading, but further studies are neededto increase the understanding of perspective difference.     

Generating labor requirements and rosters for mail handlers using simulation and optimization

In this research, we introduce a dual-purpose simulation model that integrates two decision support systems used by the US Postal Service to configure and staff their mail processing and distribution centers (P&DCs). The first system is designed to optimize the daily equipment schedules and the second to optimize the size and composition of the permanent workforce. Large-scale integer programs are solved in both cases. Because some compromise is needed in the time granularity, it is important to have an independent means of validating the results. This is the first purpose of our simulation model. The second involves the generation and validation of labor requirements for a category of workers known as mail handlers. While there is a one-to-one relationship between machine operators and the equipment schedule derived from the mail arrival profiles, no such relationship exists for those responsible for moving the mail between workstations. Neither productivity measures nor formal work rules exist. To resolve this shortcoming, we use simulation again, but this time to estimate mail handler requirements and then to determine whether the weekly schedules derived from the staff optimizer are adequate to meet the facility's service standards. Holistically speaking, the simulation serves as a bridge between the two optimization systems. The procedure is demonstrated with data provided by the Dallas P&DC.