应用CFD软件对发动机气道进行设计优化

发动机进排气系统的气体流动特性复杂,影响发动机的充气效率和换气损失,对发动机的动力性和经济性有重要影响.进气道结构复杂,关键部位尺寸对进气流动影响很大,因此找到这些关键部位并合理修改结构是进气道改进工作的重点.     

Provably secure and efficient proxy signature with untrustworthy proxy signer

Proxy signature has drawn great concerns.However, there still remains a challenge to construct a provably secure and effcient proxy signature scheme.In this paper, we propose an effcient proxy signature scheme based on factoring, and prove that it is secure in the random oracle.Furthermore, we present a new type of proxy signature, called Proxy Signature with Untrustworthy Proxy Signer, and construct a concrete scheme.     

Numerical research on wave-making resistance of trimaran

A 3D rankine panel method was developed for calculating the linear wave-making resistance of a tri-maran with Wigiey hulls. In order to calculate the normal vector and derivative of the body surface accurately,non-uniform rational B-spline (NURBS) was adopted to represent body surface and rankine source density.The radiation condition is satisfied using the numerical technology of staggered grids. Numerical results showthat the linear wave-making resistance of the trimaran can be calculated effectively using this method.     

Formal or Informal? The Dispute Settlement Mechanisms of China's Free Trade Agreements

The dispute settlement mechanism (DSM) has long been the focus of attention because of its significant role in the institutional construction of China’s free trade agreements (FTAs). Thus, this paper is to make an analysis of the DSMs of China’s established FTAs from a legal perspective of international regime study, which leads to the finding of a co-existence mode of formal and informal DSMs in China’s FTAs. This paper also discusses the motivation and significance of such a choice.     

Control strategy research of a selective catalytic reduction system for heavy-duty application

An AdBlue dosing control strategy of the selective catalytic reduction(SCR) system is developed for a heavy-duty diesel(HDD) engine. The strategy includes a raw emission prediction model, an ammonia(NH_3)coverage prediction model, a transient heat hysteresis correction algorithm, an NH_3 leakage control model for transient operation conditions, and a feedback controller(FBC). FBC has been developed by using mathematical manipulation to change output signal of sensor based on cross-sensitivity of nitrogen oxide(NO_x) sensor to NH_3.The quantification of control parameters is based on experiments and Nyquist stability criterion. FBC is enabled in most test conditions to satisfy the stability requirements. NOxconversion(DeNO_x) efficiency of SCR system is 82.4% in European steady-state cycle(ESC) test and 80.3% in European transient cycle(ETC) test, while the leakage of NH_3 is under 10-5 volume fraction in average.     

铁路轮对压装机组焊工艺

以铁路轮对压装机为研究对象,介绍了压装机的基本结构特点,具体描述了主立柱和移动立柱的制造工艺流程,并对其难点进行了具体分析,针对工艺难点以及实际生产中易出现的工艺问题,提出了解决方案。     

宁波舟山港老塘山港区锚地资源紧缺原因分析及对策

为有效解决宁波舟山港老塘山港区船舶停泊锚位需求与锚地资源紧缺的矛盾,搜集老塘山港区锚地的船舶数据,从船型分布、吨位分布进行规律分析,并将理论与数据相结合,针对老塘山港区锚地资源紧张的主要原因提出相关对策:开发新的锚泊技术;开发新的锚地资源;优化现有锚地资源;强化监管技术;协同码头、航道、锚地三方,提高效率。     

“一带一路”国家高速铁路新建线路技术规章体系构建研究

随着“一带一路”倡议的推进和中国铁路“走出去”战略的实施,铁路技术规章体系国际化的要求日益迫切。从我国技术规章体系入手,以印度尼西亚、泰国为主要分析对象,分析我国技术规章应用的适应性,提出以单一层次技术规章体系为核心,将车务、机务、工务、供电、车辆等专业合并为运营管理、动车组运用维护、固定设施维护和信息系统4个部分的体系架构,并指出各个部分应最少具有的技术规章以及其对应参考的国内技术规章,为“一带一路”国家高速铁路新建线路规章建设提供参考。     

快速密封装置在密封测试中的应用

本论文介绍了一种管件快速密封接头采用机械封堵方式对非标准的特殊管件进行密封。     

电动汽车电池冷板微小通道结构优化研究

为对车用电池微小通道冷板结构进行优化,探究冷板流道中流场和温度场的相互作用机理,本文中首先采用正交试验得到了冷板整体的最优布局。使用面向中心的中心复合设计响应面法(FCCCD)研究发现,当波纹通道振幅为1 mm、周期数为4时,波纹通道的综合热力水力性能达到最大,相对平直通道的增幅为17.4%。CFD分析表明,场协同角和通道努塞尔数一致的变化规律证明了场协同理论可以用于解释微小通道内的强化换热。波纹通道曲率的存在导致的流道内的对流混乱大大增强了流体的混合,并破坏了剪切层。该剪切层在流道内分离了主体流和再循环流,因而导致了传热的增强。