体外预应力节段预制拼装混凝土梁疲劳试验研究

为研究体外预应力节段预制拼装混凝土梁的抗疲劳性能,设计制作了1∶3缩尺模型,进行设计荷载下的疲劳模型试验研究。综合对比国内外多种疲劳荷载计算方法,确定试验疲劳等效荷载;在此基础上,进行了体外预应力节段预制拼装混凝土梁的抗疲劳理论分析和200万次疲劳加载试验。理论分析结果表明,节段预制拼装梁包含的混凝土和体外预应力构件抗疲劳能力具有较大余量,不控制结构的耐久性;试验结果表明,模型在200万次疲劳加载后,各部位均未发现疲劳裂纹,模型的力学特性未随循环次数的增加而发生明显改变,验证了结构设计的合理性和安全性。     

Health externalities of ship air pollution at port – Piraeus port case study

This paper is employing the well-known methodology of impact pathway approach to assess the external costs in human health from ship air pollution at port areas. The passenger port of Piraeus, Greece is the scenery of the study. Piraeus port is in the vicinity of the greater Athens metropolitan area where almost half of the country’s population lives. Hence, this port is the central hub of the Greek coastal passenger ship system which connects the islands of the Aegean Sea with land and is characterized by heavy ship traffic. The case study presented in this paper assesses the annual external cost in human health from air emissions produced by all passenger ships and cruise ships calling the port of Piraeus. Health cost from ships at port has been estimated at both local (Athens metropolitan area) and regional level (entire territory of Greece). Results show that higher costs occur at the local level. The dominant pollutants creating this cost are particulate matter (PM_2.5, and PM₁₀). Overall, the results indicate that the health impact of Piraeus’s passenger port emissions is not negligible; however the cost of PM₁₀ is considerably lower than the corresponded cost deriving from the land based industries of the Athens regional area for which comparison has been available.     

城市小汽车出行成本计量模型研究

在出行成本定义的基础上,提出了城市小汽车出行成本的构成,构建出城市小汽车出行成本各构成部分的计算模型。基于对广州市小汽车的出行成本分析计算,根据计算结果及各部分成本比例,对我国城市小汽车发展对策进行研究探讨。     

舰船 RCS 测试内外结合定标方法

针对舰船 RCS 测试的定标问题，讨论从接收机前端注入标准微波信号或从发射机耦合发射功率输入接收机前端的2种内定标方法，作为修正外场定标的依据。根据雷达方程分析外场定标 RCS 测量设备、标准体加工、目标跟踪定位、测试区域环境等主要误差因素。讨论发射功率、系统非线性、系统稳定性、极化损耗等引入的误差，提出外场定标对标准体几何尺寸、表面光洁度以及所需信噪比等要求。通过内定标与外定标相结合的方法，解决由于定标与测试间隔时间过长接收机状态出现漂移导致测试误差的问题，保障舰船 RCS 长时间测试的精度和稳定度。     

墨西哥NOM标准下雷电防护系统设计的解决方案

针对墨西哥的NOM标准对于建构筑物雷电防护系统的设计规定与国标GB 50057和美标NFPA780差异较大的问题,基于墨西哥某集装箱码头工程,对墨标、国标、美标在建筑物防雷风险评估、年预计雷击次数、可承受雷击次数、外部防雷措施、接闪器、引下线及接地系统等方面进行分析比较,得出墨标在防雷风险评估及外部防雷措施上与国标及美标的主要区别点及雷电防护系统的设计步骤。结果表明,墨标以建筑物年预测雷击次数与规定的可承受雷击频率比较来确定是否需要设置外部防雷措施,国标的防雷分类法已经考虑了风险权重且易于执行,美标风险评估方法相对更复杂。     

海洋救助拖船救助功能与配置研究

海洋救助拖船是对海上遇险人员和船舶实施有效救助的专用船舶.为对接我国海洋战略发展需求,要适应在深远海大风浪恶劣海况条件下对海上遇险人员和船舶的有效救助.针对海洋救助拖船适应深远海救助需求的基本功能设置,就船舶救助和人命救生的拖曳救助作业、对外消防灭火、海面人命救生、海面搜救、获救人员救治及保障等主要设备及设施配置作技术探讨.     

Evaluating Locations for Intermodal Transport Terminals

Abstract

The choice of location for an intermodal transport terminal is an important component in a regional logistics system and a paramount decision for the investor as well as the community affected. The investor needs a realistic estimation of traffic potentials and incorporated cost-estimates of a location, since it serves as an important input to the investment decision process. Policy makers need instruments and tools to analyse the effect of intermodal terminals on the surrounding environment, which also enables a comparison between several possible locations in order to ensure sustainability and long-term competitiveness. The model in this paper allows a comparative evaluation of a set of possible intermodal terminal locations based on considerations by relevant actors. Furthermore, it presents a process of retrieving data and effectively communicating results. Considerations and interests of stakeholders are incorporated into the approach by means of evaluative criteria. The approach aims at facilitating the planning process of regional logistics systems in general and the evaluation process of intermodal terminal locations in particular by considering both public and private interests focusing on economic and environmental aspects.     

体外预应力混凝土梁接缝剪切性能及影响因素分析

接缝作为节段施工体外预应力混凝土桥梁的关键构造,也是施工薄弱环节,其力学性能直接影响桥梁整体的承载能力。依托广州市"体外预应力节段施工新技术研究"科技计划项目,以广州地铁4号线节段施工体外预应力混凝土梁为参照,采用ANSYS有限元程序建立梁的非线性数值分析和对比模型,分析节段施工体外预应力混凝土梁接缝处的剪切性能及其影响因素,得出模型梁干接缝直接剪切模式下的受力分布规律,以及接缝构造类型、混凝土强度和接缝界面的粗糙程度等对体外预应力混凝土梁剪切性能的影响程度,供工程实践参考。     

综合蓄热法在桥梁工程冬季施工中的运用

通过理论分析并结合临离高速公路工程实例,说明在严格的冬季施工管理的情况下,通过采取包裹和其他热源对混凝土进行保温的方法是可以保证冬季施工混凝土的质量的,达到了预期的效果和目的,为类似工程施工提供参考。     

三塔部分斜拉桥结构体系的分析研究

该文以京承高速公路潮白河大桥为工程背景,介绍了三塔部分斜拉桥结构体系的选择过程,并通过数值分析比较了不同结构体系在外部作用下的反应,以及采用阻尼器降低结构地震效应的措施。