连续梁预应力部分施工中的关键工序研究

连续梁桥是中等跨径桥梁中常用的一种桥梁结构,预应力混凝土连续梁桥是其主要结构形式,它具有接缝少、刚度好、行车平顺舒适等优点,其中,预应力是连续梁施工的重点和难点。以新建太中银铁路跨石中高速公路特大桥连续梁施工为例,对影响预应力部分施工的关键要素进行简要阐述。     

An Experimental Study on the Dynamic Response Characteristics of Variable Valve Timing Mechanism

为一台可变气门正时(VVT)发动机的配气相位调节器开发了一套可变气门正时机构的测试系统,完成了机油控制阀(OCV)工质流量特性的测试.分析了VVT动态响应特性的测试原理.借助该测试系统,测得不同的OCV、转速、温度和压力时相位器的动态响应曲线.最后进行了相位器泄漏量的测试.     

基于WORD模板的科技成果申报系统的设计与实现

结合为某军工企业开发的科技成果申报管理系统，提出了基于WORD模板的科技成果申报系统的解决方案，以WORD文档作为申报流程中的流转媒介，结合关系数据库技术和模块化的软件设计技术，实现WORD和数据库之间的数据交互，保证了申报流程的高效运转，实现了申报流程的“无纸化”管理。     

长江通航安全研究的船舶操纵仿真系统

长江水域通航条件高度复杂，有针对性地开展船舶操纵模拟系统的研究显得尤为重要，文中介绍了全功能大型船舶操纵模拟器及通用船舶操纵计算机仿真平台（USManCSP），提出以前者砻实时模拟基础，结合USManCSP中的电子江图信息系统（ECS）、内河船舶操纵运动数学模型、基于模糊控制的引航员控制模型等进行快时模拟研究，建立较完善的通航安全论证分析平台，并给出了二个急弯河段的模拟研究结果．     

Constructal design of tree-shaped microchannel disc heat sink with wavy walls北大核心CSCD

［Objective］To meet the efficient thermal management needs of electronic devices such as ships and underwater vehicles, this study focuses on the constructal design of a tree-shaped microchannel disc heat sink with wavy walls. ［Method］A design prototype of the heat sink with wavy walls is first proposed. Based on constructal theory, the amplitude and wavelength of the wavy walls are designed under the constraints of fixed heat sink volume and fixed microchannel volume by maximizing the comprehensive performance evaluation criteria (PEC) while considering both heat transfer and flow pressure drop. ［Results］The results show that the wavy walls increase the heat transfer surface areas and generate vortices in their cavities, effectively reducing the maximum temperature. When the inlet Reynolds number is fixed at 700, 900 or 1100 respectively, the maximum temperature is reduced by 13.5 K by increasing the amplitude of the wavy walls, while the pressure drop increases significantly; and the maximum temperature is reduced by 4.7 K by reducing the wavelength of the wavy walls, while the pressure drop increases slightly. There are optimal amplitudes that raise the comprehensive performance evaluation criteria to extreme values for given larger wavelengths, while the comprehensive performance evaluation criteria increase monotonously as the amplitude increases for given smaller wavelengths. ［Conclusion］Wavy walls can significantly improve the thermal performance of tree-shaped microchannel disc heat sinks, and the use of constructal design can realize optimal geometric constructs with optimal comprehensive performance evaluation criteria. © 2023 Authors. All rights reserved.     

试论DSC设备性能要求与测试检验方法的规范化

本文阐述了在我国规范DSC设备性能要求与测试检验方法的必要性和紧迫性,讨论了DSC设备性能要求与测试检验方法规范化的基本内容。     

抓住发展机遇办好航海教育

分析21世纪国际船员劳务市场的现状及发展趋势,探讨在STCW78／95公约实施中,航海人才日益国际化的新形势下,如何深化航海教育改革的问题。     

E 5 5灌包机称量域扩展可行性实验

1　问题的提出 　　我公司使用的E55灌包机作为整个卸灌系统的有机组成部分,是为配合整个散装化肥卸灌系统而配置的。随着公司经营的多元化发展,港口的散货装卸主要货种已由原先的单一货种化肥转变为化肥、粮食、饲料、硫磺、原糖等多货种。由于各货种的灌包重量不同,所以原先定量点为50 kg的灌包机无法对粮食等货物进行灌包作业,影响了灌包机的利用率。 　　能否将现有的灌包机的称量域扩展到满足多货种灌包的需要呢?有两种考虑：     

Experimental research on dynamic responses characteristics and influence laws of gear transmission-propulsion system under gear excitation北大核心CSCD

［Objective］In order to study the dynamic response characteristics and influence laws of a marine gear transmission-propulsion system, a series of bench tests is carried out.［Methods］First, a biaxial gear transmission-propulsion system test bench including a cross connection gear is built. Experiments to test the acceleration response of the gearbox body and propulsion shaft system are then carried out, and the influence of speed, driving mode, axial static thrust, axial dynamic excitation force from the propeller and other factors on the dynamic response characteristics of the system are compared and analyzed. ［Results］The experimental results show that the transmission law of the vibration acceleration response of the gear transmission-propulsion system is mainly at the meshing frequency and its multipliers, as well as peaks in the low frequency band of 30–80 Hz under certain working conditions. ［Conclusion］This study can provide technical support for the vibration and noise reduction design of gear transmission-propulsion systems. © 2022 Journal of Clinical Hepatology. All rights reserved.