减小簇头边缘化的LEACH协议的研究及改进

为减少无线传感器网络能耗、延长网络的生存周期,基于经典的LEACH,提出了一种新的能量有效的分簇算法.算法的主要思想是考虑节点当前剩余能量和簇头不边缘化来优化簇头选择,从而在使簇头分布更均匀的同时,进一步保证了网络内簇头节点的最大覆盖化,优化了网络的负载均衡.仿真和分析表明,该算法是一种有效的分簇路由算法.     

三相坐标系下带非平衡负载的船舶电力系统的仿真与实验

船舶电力系统中存在着大量的非平衡负载,必将引起中性点电势的漂移,在传统的dq0坐标系下很难进行研究.在三相坐标系下各元件的数学模型中引入中性点电势,然后在三相坐标系中对典型的非平衡负载情况进行了仿真研究,并进行了实验分析.仿真与实验结果的比较证明,在三相坐标系下仿真分析带非平衡负载的船舶电力系统是准确可靠的.     

Product substitution and dual sourcing under random supply failures

Product substitution can mitigate supply chain disruptions. However, it may not be very effective without multiple sourcing. In this paper, we consider a supply chain with two downward substitutable products. The products can be ordered from an unreliable supplier or a reliable but more expensive supplier. It is found that in an optimal sourcing policy the higher-grade product should be preferred over the lower-grade product. A sufficient condition is given for an optimal policy where only the higher-grade product is dual-sourced. The effect of substitution is contrasted with the non-substitution case. Numerical study shows the impact of demand variability and correlation on the effect of product substitution and the corresponding optimal sourcing policy.     

钻孔咬合桩及超缓凝混凝土综合施工技术

介绍分析了深基坑围护结构中全回转、全荤桩钻孔咬合桩技术。该工艺与原有一素桩间隔一荤桩的老工艺相比,具有桩身垂直度佳,围护止水效果好,开挖后桩身刚度大,抵抗变形能力强等特点,更适合于环境保护要求高的深基坑围护工程。介绍了该工艺在上海轨道交通建设工程中的应用以及超缓凝混凝土的配制方法和生产质量控制要点。     

衬砌弹性模量对圆形隧洞动力响应的影响研究

基于Biot理论,分析研究了衬砌与饱和土体弹性模量之比的变化对衬砌隧洞动力响应的影响.假定隧洞衬砌为弹性体,土体为饱和多孔介质,结合边界条件及连续条件,通过傅立叶变换得到频率-波数域中衬砌和土体的应力、位移和孔隙水压力等动力响应解答,最后用傅立叶积分逆变换得到时-空域中圆形衬砌隧洞在移动环形荷载作用下的动力响应的数值解...     

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。