舰船无线通信设备的干扰建模和性能分析

利用随机几何理论建立了舰船无线通信设备的干扰模型,并在此基础上分析了多种信道参数对无线通信设备性能的影响.本文首先理论分析了在舰船环境下的无线通信干扰源分布的系统模型.其次,基于随机几何理论讨论了船体区域中的干扰对无线通信设备性能的影响,并给出了干扰和积分形式的表达式.最后仿真分析了多种无线通信信道参数对设备性能的影响.仿真结果表明,信道状况对无线通信设备的性能有很大的影响,合理部署无线通信设备可有效的改善无线通信性能.     

Numerical simulation of the water entry of a structure in free fall motion

To solve the problems concerning water entry of a structure, the RANS equations and volume of fluid （VOF） method are used. Combining the user-defined function （UDF） procedure with dynamic grids, the water impact on a structure in free fall is simulated, and the velocity, displacement and the pressure distribution on the structure are investigated. The results of the numerical simulation were compared with the experimental data, and solidly consistent results have been achieved, which validates the numerical model. Therefore, this method can be used to study the water impact problems of a structure.     

Scheduling highway work zones with genetic algorithm considering the impact of traffic diversion

Highway work zones caused excessive delay to road users. To reduce user and maintenance costs, work zones shall be designed and scheduled accordingly. An analytical model is developed to jointly optimize work zone lengths and schedule as well as diverted traffic volume for highway maintenance projects, considering time‐varying demand, variable maintenance cost, and various production rates of maintenance crew. With a genetic algorithm, an iterative procedure is developed to search for the optimal solution. A numerical example is illustrated, in which various traffic mitigation plans for a highway maintenance project are evaluated. A sensitivity analysis is conducted, and results indicate the threshold volumes for various conditions (e.g., maintenance crews and capacity of the work zone) at which diverting traffic is desirable. This study demonstrates an effective approach to search for the optimal work zone schedule, which is also applicable to evaluate the effectiveness of traffic diversion plans for a pre‐planned work zone schedule. Copyright © 2012 John Wiley & Sons, Ltd.     

A dynamic model of an underwater quadruped walking robot using Kane’s method

In this paper, the kinematics and dynamics of an underwater quadruped walking robot were derived based on Kane dynamic equations. This methodology allows construction of the dynamic model simply and incrementally. The velocity and angular velocity components of an underwater quadruped walking robot were served as the generalized velocities. The forces which contribute to dynamics of an underwater quadruped walking robot were determined by Kane＇s approach. The equations of hydrodynamic forces of an underwater quadruped walking robot were deduced. Hydrodynamic coefficients were determined by experiments. The dynamic model was established by obtaining the generalized active forces and the generalized inertia forces. Numerical simulations of the walking behavior on underwater flat ground were implemented to verify the dynamic model of an underwater quadruped walking robot. Simulation results show that the dynamic model is correct.     

Aesthetic visual style assessment on Dunhuang murals

Dunhuang murals are gems of Chinese traditional art. This paper demonstrates a simple, yet powerful method to automatically identify the aesthetic visual style that lies in Dunhuang murals. Based on the art knowledge on Dunhuang murals, the method explicitly predicts some of possible image attributes that a human might use to understand the aesthetic visual style of a mural. These cues fall into three broad types: ① composition attributes related to mural layout or configuration; ② color attributes related to color types depicted; ③ brightness attributes related to bright conditions. We show that a classifier trained on these attributes can provide an efficient way to predict the aesthetic visual style of Dunhuang murals.     

主动前轮转向的操纵稳定性研究

汽车的主动前轮转向作为汽车主动控制的一个重要组成部分,可以改善车辆的操纵稳定性;横摆角速度与质心侧偏角作为表征车辆操纵稳定性的2个主要指标,可以作为车辆处于稳定状态的参考。基于模型预测控制方法,在汽车线性二自由度模型的基础上,使用相同工况下理想的横摆角速度与质心侧偏角作为参考,设计了模型预测控制器,将二自由度汽车模型与CarSim整车模型进行了联合仿真。结果表明:模型预测控制方法相对PID控制方法更能有效地提高汽车的主动安全性。     

乘用车内饰四连杆机构设计探讨

为节约乘用车内部空间,提出了一种四连杆机构设计方法,以计算四连杆的杆长及改进桌板类机构,实现了所要求的闭合与开启位置。     

基于飞思卡尔32位Kinetis-K60单片机的直立行驶智能车设计

介绍一种基于线性CCD传感器进行路径识别的智能车控制系统。进行了软硬件设计,利用线性CCD传感器采集路径信息,以及陀螺仪和加速度计采集角度偏转信息,提出转向控制策略和速度控制策略,控制2个电机的动作,从而实现了直立行驶。实验证明:该智能车抗干扰性强、精确度较高,可自主寻迹稳定行驶。     

基于Crotex-M3和GPRS的远程监测系统的研究

研制出了一款运行高效、成本低、通用性较强的电梯运行状况监测系统。系统基于具有Crotex-M3内核的高性价比嵌入式系统,采集电梯各类传感器信息,获取电梯运行方向、平层状态、门状态、温湿度以及电梯内是否有人等多参数数据,再通过GPRS将数据发送至数据中心。根据电梯的运行数据,判断电梯是否正常运行,以及紧急情况下进行自动报警,实现了多区域内电梯运行状态集中监测和故障自动报警。系统实际运行效果良好,通用性强,可以满足多种型号电梯的监测。     

低压平行集束导线在农村配电网改造中的应用

本文综述了低压平行集束导线国内外研究及应用现状,介绍了当前我国使用低压平行导线模式的标准、电气性能技术参数。实际应用中平行集束导线供电模式在降低工程造价、降低线损、减少末端电压降等方面具有显著的经济效益,在我国农网低压改造中应用广泛。