Influence on the hydrodynamic performance of a variable vector propeller of different rules of pitch angle change

To design a more effective blade pitch adjustment mechanism,research was done on changes to the hydrodynamic characteristics of VVPs(Variable Vector Propeller) caused by different rules for changing pitch angle. A mathematical method for predicting the hydrodynamic characteristics of a VVP under unsteady conditions is presented based on the panel method. Mathematical models for evaluation based on potential flow theory and the Green theorem are also presented. The hydrodynamic characteristics are numerically predicted. To avoid gaps between panels,hyperboloidal quadrilateral panels were used. The pressure Kutta condition on the trailing edge of the VVP blade was satisfied by the Newton-Raphson iterative procedure. The influence coefficients of the panels were calculated by Morino's analytical formulations to improve numerical calculation speed,and the method developed by Yanagizawa was used to eliminate the point singularity on derivation calculus while determining the velocities on propeller surfaces. The calculation results show that it's best for the hydrodynamic characteristics of the VVP that pitch angle changes follow the sine rule.     

基于哈佛结构和群集智能的集装箱码头物流系统建模优化

在当前港口间竞争日益白热化的背景下,集装箱码头物流系统(Container Terminal Logistics Systems,CTLS)生产调度和管理决策水平的高低对于其提高自身运作效率和通过能力,具有至关重要的作用.利用基于Agent的计算及源于Agent 技术的群集智能,在基于仿真的优化的思想下,提出基于哈佛结...     

不同拌和方法对沥青混合料体积指标的影响

通过对流动拌和方法与传统拌和方法生产的沥青混合料体积指标的测试,比较了不同拌和方法对混合料体积指标的影响,同时判断流动拌和方法是否具有降低拌和温度和沥青含量的可能。     

交通信号机仿真器设计及实现

针对交通信号控制系统在通信性能测试过程中难以采用大量真实交通信号机的问题.首先分析了仿真测试平台对信号机仿真器的设计需求,接着提出了信号机仿真器的功能结构设计,并采用Visual C++6.0语言加以实现,开发出的1款信号机仿真器软件在自搭建的仿真测试平台下对系统通信性能进行测试验证.结果表明,信号机仿真器软件达到了各项设计功能与性能指标,是稳定可行的.     

线控四轮独立转向系统的结构及控制研究

主要介绍了四轮转向汽车以及线控转向技术的优点,设计了一种线控四轮独立转向汽车的总体结构,说明所设计的转向系统相对其他转向系统的优点。建立四轮转向汽车的3自由度数学模型,找出四轮转向汽车各车轮转角与转向盘转角的关系。对模型前后轮转角对质心侧倾角和横摆角速度的影响做了Matlab／Simulink仿真,考虑影响汽车行驶安全的因素,找出不同车速和前轮转角对应的最佳后、前轮转角比例系数,从而确定了高速行驶的汽车在指定车速与转向盘转角时各车轮对应的转角。     

大众迈腾第三代EA888发动机控制单元、传感器针脚定义及对应故障码解析

<正>掌握电控汽油发动机控制单元及传感器、执行器各针脚定义,是职业院校汽车检测与维修专业专任教师的必修课。同时,也是汽车售后服务部门一线汽车维修技师必须掌握的一项专业技能。作为职业院校汽修专任教师唯有掌握了电控发动机传感器、执行器的工作原理、信号控制逻辑,才能在“电控汽油发动机维修”课程教学过程中得心应手。笔者通过平时的一线实践教学,对该款发动机相关传感器针脚定义及对应故障码进行收集整理,供业内人士在工作中参考。     

一种改进的小波消噪算法

针对传统小波变换在信号消噪中计算的不足,设计了一种改进的小波消噪算法.该算法保留了小波分析处理时变信号的优势所在,但较传统的消噪应用,算法相对简单,易于实现.利用实际数据对该消噪算法进行了数据验证,并与传统小波消噪算法等对比算法进行了效果对比.验证结果表明,所提出的新算法效果较好,具有一定实用性.     

椭圆沉箱墩式码头新结构的研究与设计

大连矿石专用码头二期工程是具有可卸船、又可装船功能的专业矿石码头,作为开敞式码头,对码头面顶高程提出了限制要求.通过物理模型实验进行外力分析,结合理论计算,该工程断面上首次采用1个椭圆沉箱重力墩式结构,取代传统的2个小直径圆沉箱或1个大直径沉箱.     

聚氨酯夹层隔振特性及模型试验研究

The vibration isolation performances of typical hull structure with viscoelastic interlayer are analyzed ac-cording to wave theory, and the influences of interlayer Young's modulus and length on the vibration reduction are dis-cussed. The theoretical analysis shows that combination of polyurethane interlayer with blocking mass can enhance the vibra-tion isolation performance and expand isolation frequency band. In order to verify the effectiveness of polyurethane interlay-er, the model test of power cabin's vibration is carried out. The test data shows that the reduction of 20–1000 Hz variation acoustic level at hull shell is more than 5 dB.