Aerodynamic characteristics of airship Zhiyuan-1

An airship named ＂Zhiyuan-l＂ was designed/fabricated/flied as a technical demonstration for stratospheric airship during 2007--2009 by Shanghai Jiaotong University. The calculation method and procedure of aerodynamic parameters were introduced, and the optimized configuration of the hull and the aerodynamic layout were given in this paper. Wind tunnel tests with different configurations, different pitch angles and different yaw angles were performed to study the wind load characteristics of the rigid model of the airship ＂Zhiyuan-1＂ in the φ3.2 m wind tunnel at China Aerodynamics Research ＆ Development Center. Also the numerical calculation about the test model was carried out to investigate the aerodynamic behavior. According to the results of wind test and numerical calculation, the excellent hull configuration of the airship ＂Zhiyuan-1＂ with lower drag characteristic was confirmed, which is based on optimism of the Michel transition law. And the phenomena of pressure coefficient distribution were discussed according to the results of wind tunnel test and numerical calculation at different flight attitudes.     

螺洲大桥主缆缠丝及其导入力对主缆结构的影响分析

为了对悬索桥的主缆做好防护,选用不同直径及不同弹性模量计算了先铺装后缠丝、先缠丝后铺装2种工序下的缠丝导入力。结果表明,随着缠丝弹性模量和缠丝直径的增加,缠丝导入力增加,断面温差对缠丝导入力的影响不容忽视。为了节省工期同时保证施工质量,采用先铺装6cm聚丙烯混凝土再缠丝的施工方法,主缆缠丝导入力采用2 500N。     

空压机余热利用及节能效益分析

空压机余热回收是指一项新型高效的余热利用回收技术,依靠吸收空压机运行时产生的废热使水加热,再将加热的水用于员工的生活、工业用所需,没有太大的能源消耗。作为一种新型高效的余热利用技术,可以为企业节省能源的消耗,从而节省大量的成本。     

轮胎运动包络计算分析流程和方法

主要针对乘用车常用的麦弗逊式前悬架,论述此悬架型式下轮胎运动包络计算分析的流程和方法,涉及整车、子系统要求、车辆动力学及试验验证等方面的内容,比较全面的讨论了整个计算分析过程.     

Predicting duration of traffic accidents based on cost-sensitive Bayesian network and weighted K-nearest neighbor

Abstract

With the development of urbanization, road congestion has become increasingly serious, and an important cause is the traffic accidents. In this article, we aim to predict the duration of traffic accidents given a set of historical records and the feature of the new accident, which can be collected from the vehicle sensors, in order to help guide the congestion and restore the road. Existing work on predicting the duration of accidents seldom consider the imbalance of samples, the interaction of attributes, and the cost-sensitive problem sufficiently. Therefore, in this article, we propose a two-level model, which consists of a cost-sensitive Bayesian network and a weighted K-nearest neighbor model, to predict the duration of accidents. After data preprocessing and variance analysis on the traffic accident data of Xiamen City in 2015, the model uses some important discrete attributes for classification, and then utilizes the remaining attributes for K-nearest neighbor regression prediction. The experiment results show that our proposed approach to predicting the duration of accidents achieves higher accuracy compared with classical models.     

意大利摩托车和轻便摩托车市场最新发展情况

意大利是欧洲最大的两轮机动车市场,意大利的摩托车、轻便摩托车产业也一直处于世界领先地位,技术含量较高,从20世纪初开始,意大利就涌现出许多著名的摩托车品牌。虽然2010年意大利摩托车销量下滑,但全年注册量仍位于欧洲首位。     

平旋转推进器拆装修理

通过对平旋转推进器拆装修理，积累了对特种推进器装置修理的经验，可供参考。     

爆破排淤填石法在锦州港的应用

爆破排淤填石法是处理水下软基的有效方法,具有工艺简单、施工速度快、造价低、建筑物稳定性可靠等特点。结合锦州港三、四港池防波堤及围堰工程,介绍采用爆破排淤填石法处理水下软基的施工工艺及效果,可为类似工程的施工提供借鉴经验。     

长传动轴机车静液压变速箱位置度测量方法改进

DF_(4C)及DF_(4D)型机车柴油机与静液压变速箱之间跨距在1500～1600mm以上,传统的假轴测量已不适应,显露出一些弊端、缺陷。为满足现场检测的要求,设计了一套轻便、精准的测量机具。     

商贸企业内部审计执行买卖合同审签的控制程序

以中国铁路物资哈尔滨公司为例,介绍了内部审计执行合同审签所采取的合同草案审核控制、合同履行过程控制、合同履行结果控制等具体程序,结合工作实际探讨了内部审计部门执行控制程序应当关注的具体问题.