简报燃气轮机涡轮导叶热管冷却效果对比研究

以一种涡轮直叶片为研究对象,分别采用热管冷却和冲击冷却对其进行气热耦合数值模拟计算,对比分析两种冷却方式的效果.通过对叶片的表面温度、中截面的换热系数以及总体冷却效率的对比,分析结果表明,使用热管冷却时,叶片尾缘的温度分布更加均匀,转捩点附近低温区范围分布更广.在相同的主流条件下,热管冷却能达到甚至超过冲击冷却的效果.     

基于SCI引文的物流合作研究网络分析

本文基于社会网络分析方法,利用UCINET软件,以2008-2012年SCI收录的物流论文为基础,对世界物流研究领域的合作研究趋势、跨国家或地区的物流研究合作变化以及主要国家或地区间的合作研究情况进行了分析.研究发现近五年来在物流研究领域研究人员合作比较紧密,美国在物流合作研究领域占据最核心的地位,资源控制能力最强,而中国等亚洲国家的物流研究跨国家或地区的合作也不断增加.     

乌鲁木齐地区气候要素若干特征及变化趋势研究

利用乌鲁木齐地区10个水文气象站50多年(1961～2012年)气象资料,对乌鲁木齐地区平均气温、降水量、相对湿度主要气候要素的若干特征及趋势变化进行研究。结果表明,近50多年来,乌鲁木齐地区年平均气温增温趋势最强的是北部平原地区,贡献最大是冬季增温显著;乌鲁木齐年平降水量增加趋势最强的是北部平原地区,贡献最大是夏季降水量增加显著;乌鲁木齐地区增湿趋势最强的南部中山带和高山带,以冬季(1月)气候倾向率最大对全年相对湿度增加贡献最大。20世纪80年代开始增温度和增湿及降水量增大,21世纪初度和增湿及降水量增幅达最大。创新点在于,建立无资料地区气候要素预测模式,发现乌鲁木齐地区年平均气温、年降水量随海拔高度增高遵循多项式分布。为水资源影响机理提供理论基础,为当地政府制定气候变化背景下水资源合理利用提供决策支持。为乌鲁木齐地区中山带水利工程建设提供科学依据。     

幼儿“经典诵读”之路该何去何从

在20世纪末,台湾台中师范大学王财贵教授在台湾地区倡导幼儿“经典诵读”。此举受到世界各地华人响应,由此,形成了一场轰轰烈烈的“经典诵读运动”。“经典诵读”在实践中进行得如火如荼,但是,学术理论界却围绕是否应该开展此活动掀起了一场争论飓风。本文根据笔者搜集的部分相关资料对幼儿经典诵读的研究进行了总结概述,对争论双方的各自理论观点和主要争论焦点进行了分析说明,同时对幼儿经典诵读提出了自己的一些看法。     

Mars entry guidance based on nonlinear model predictive control with disturbance observer

This paper investigates entry guidance of a capsule for pinpoint landing on Mars. In this scenario, the capsule is subject to the external disturbances caused by the atmosphere that can result in control saturation, and then undesired landing errors. To this end, a new guidance scheme to satisfy entry constraints, high-accuracy landing at high elevation sites, is proposed. The technical contributions of this work are two-fold: first, in order to mitigate the effects caused by large disturbance, a function describing the joint constraints of bank angle and slacked height is proposed; based on the nonlinear model predictive control (NMPC), a new algorithm is developed, where the constraints of dynamics, bank angle, slacked height, are sufficiently considered and precisely modeled; second, a state-space observer to improve the prediction of disturbance is introduced, which can significantly improve the accuracy of landing performance. The numerical simulations show the feasibility and validity of the proposed scheme.     

Evaluation of wireless bat swing speed sensors

Batter swing speed is an important parameter in understanding the performance of baseball and softball players. A number of swing speed sensors have recently been introduced and are commercially available. The aim of this study was to compare three wireless swing sensors with high speed video. Swing speed from high speed video was measured by differentiating the position coordinates of tracking markers on the bat barrel. On average, the wireless bat swing sensors reported speeds 8% slower than that found from video tracking. The agreement was better at low swing speeds, suggesting that the current generation of wireless sensors is best suited for developing players. Spatial measures, such as swing angle, were not in good agreement with video tracking.     

医疗卫生信息公开政策的基本研究框架与制定协同动力模型构建

医疗卫生信息公开政策是政府信息公开政策体系的必要组成内容。在分析医疗卫生信息公开政策研究背景基础上探讨了医疗卫生信息公开政策内涵,界定了医疗卫生信息公开政策研究对象,从静态和动态两个层面分析了医疗卫生信息公开政策研究内容,并初步构建了面向"对象——内容"的医疗卫生信息公开政策基本研究框架。系统分析了医疗卫生信息公开政策制定协同动力因素,并提出了医疗卫生信息公开政策制定协同动力模型。     

数字保存的可识别性风险检测

[目的]可识别性是指将一件数字对象与其他数字对象区分开来的特性,以实现该数字对象的发现和检索;设计并验证保存系统中数字对象的可识别性风险模型。[方法]阐释可识别性涵义,界定可识别性风险类型;从数字资源、保存活动与保存政策三个方面设计可识别性风险型元数据,建立可识别性风险检测方法;选择CNKI作为实验对象,实施可识别性风险检测实验,统计分析实验结果,制定降低或规避可识别性风险措施。[结论]实验结果表明,设计的数字保存可识别性风险模型是适用的。     

科技情报大数据业务平台设计

[目的/意义]本文分析了目前大数据时代科技情报工作面临的问题和机遇,针对情报服务领域大数据服务模式进行了分析。[方法/过程]该论文结合信息技术领域的虚拟化技术、云平台技术、高性能技术和人工智能技术,设计了科技情报大数据业务平台架构,详细阐述了硬件层、虚拟层、支撑层和业务层主要功能和所需技术;并对大数据处理首要任务存储进行了探索,搭建了基于hadoop和hbase的大数据存储平台。[结果/结论]本文提出的大数据情报业务平台从整体架构进行了设计,并实现了存储模块,下一步实现分析和可视化部门,可以为情报的收集和处理提供大数据支撑服务。     

Cooperative surrounding control with collision avoidance for networked Lagrangian systems

This paper investigates the cooperative surrounding control problem for networked multi-agent systems with nonlinear Lagrangian dynamics. With the consideration of the target with constant and time-varying velocity, two cooperative surrounding control algorithms with collision avoidance are proposed, in which possible collision among agents is prevented so as to achieve a more reliable and safer performance. For the case when the target has a constant velocity, a velocity observer is designed firstly for each agent. Secondly, to handle the nonlinear dynamics and avoid collisions, the neural networks and potential functions are used for the controller design. Then, the cooperative surrounding control algorithm is proposed such that all the agents surround the target with the desired relative positions. For the case when the target has a time-varying velocity, the velocity observer is designed under the assumption that the target’s partial acceleration is known for each agent. Then, the cooperative surrounding control algorithm is proposed such that the surrounding error between the target and each agent is bounded. The main difference between these two algorithms is that the former can ensure the collision avoidance among target and agents, while the latter can do so only among agents because the target’s velocity is time-varying. The Lyapunov theory is used to prove the stability of the cooperative surrounding control algorithms. The simulation illustrates the effectiveness of the theoretical results.