Visual System Simulator平台下锁相环综合分析与仿真

给出了基于VSS平台的锁相环仿真过程,并将其引入课堂教学和实验。同时给出了锁相环的仿真模型,构建了完整的锁相环系统,并给出了仿真波形与环路滤波器设计方法。实践证明,采用这种方式可以帮助学生对相关内容的理解,并为今后进行系统设计工作打下良好的基础。

Fault-tolerant FADS system development for a hypersonic vehicle via neural network algorithms

Hypersonic vehicles suffer from extreme aerodynamic heating during flights, especially around the area of leading edge due to its small curvature. Therefore, flush air data sensing(FADS) system has been developed to perform accurate measurement of the air data parameters. In the present study, the method to develop the FADS algorithms with fail-operational capability for a sharp-nosed hypersonic vehicle is provided. To be specific, the FADS system implemented with 16 airframe-integrated pressure ports is used as a case study. Numerical simulations of different freestream conditions have been conducted to generate the database for the FADS targeting in 2 ≤ Ma ≤ 5 and 0 km ≤ H ≤ 30 km. Four groups of neural network algorithms have been developed based on four different pressure port configurations, and the accuracy has been validated by 280 groups of simulations. Particularly, the algorithms based on the 16-port configuration show an excellent ability to serve as the main solver of the FADS, where 99. 5% of the angle-of-attack estimations are within the error band ±0. 2°. The accuracy of the algorithms is discussed in terms of port configuration. Furthermore, diagnosis of the system health is present in the paper. A fault-tolerant FADS system architecture has been designed, which is capable of continuously sensing the air data in the case that multi-port failure occurs, with a reduction in the system accuracy.

基于Simulation X的多轴转向系统功能安全仿真分析

基于ISO 26262《道路车辆功能安全》的标准要求,对特种车的多轴电液转向系统进行分析,以提高系统的安全性和可靠性。运用Simulation X软件建立详细的多轴特种车仿真模型,通过模拟故障模式注入进行仿真试验。对仿真结果和数据进行分析,评估得到故障的严重性、暴露度和可控性,从而确定相应的汽车安全完整性等级。基于故障注入仿真的汽车功能安全分析方法,在系统早期设计阶段可以作为评估架构安全性的重要手段。

Kinematics Analysis of Motion Simulation Subsystem for Unmanned Vehicle

Unmanned vehicle has attracted wide attention and interests throughout the world since it first deputed in the 1960s. However, the experimental methods for unmanned vehicle＇s intelligent behavior, such as semi-physical simulation and motion subsystem, have not been widely explored. First, the requirements of the motion subsystem in unmanned vehicle semi-physical facility are analyzed, and a six DOF parallel manipulator is selected to reproduce the pose of the vehicle. The link lengths of the motion subsystem are worked out under the given rotational angles of the vehicle. According to the geometric properties of tetrahedron, three joint positions of the top platform are determined, and the rest are obtained from the first three position vectors. Six constraint equations are set up based on the vertices on the top platform and the link lengths. In order to solve the six angle variables, a numerical algorithm built on the Newton-Raphson iterative method is presented, which is based on Taylor series expansion of six constraint equations. The pose of the top platform is ultimately calculated. The eigenvalues of the top platform are solved to obtain the natural frequencies of the motion subsystem. The coordinates of six joint centers on the top platform and six constraint equations can be realized by simple algebraic manipulation, which allows significant abbreviation in the formulation and provides a systematic way of obtaining the kinematic solution of the parallel manipulator. A numerical example is given and its efficacy is demonstrated by the inverse kinematics. The computation strategy based on tetrahedron method and Newton-Raphson iterative method provide a simple and cost-effective method for solving forward kinematics of six DOF parallel manipulators, and this method sheds light on other parallel manipulators.

Model Construction and Visualization Simulation of Soybean Root System

This paper mainly focused on the growth law, model construction and visualization of a soybean root. A pot experiment was conducted in the laboratory to collect root system data and measure soybean root＇s length, diameter and number by excavating in different periods. On the basis of an in-depth analysis of root structure geometry, we analyzed the collected experimental data with logistic equations, and got the growth of soybean root equation, according to its morphological structure characteristics of self-similarity, and discussed the virtual modeling method on the soybean root based on L-system and in Visual c＋＋ Using OpenGL technology to achieve a soybean root system topology model and visualization simulation.

A three dimensional visualized physical simulation for natural gas charging in the micro-nano pore system

A micro-nano pore three-dimensional visualized real-time physical simulation of natural gas charging, in-situ pore-scale computation, pore network modelling, and apparent permeability evaluation theory were used to investigate laws of gas and water flow and their distribution, and controlling factors during the gas charging process in low-permeability(tight) sandstone reservoir. By describing features of gas-water flow and distribution and their variations in the micro-nano pore system, it is found that the gas charging in the low permeability(tight) sandstone can be divided into two stages, expansion stage and stable stage. In the expansion stage, the gas flows continuously first into large-sized pores then small-sized pores, and first into centers of the pores then edges of pores;pore-throats greater than 20 μm in radius make up the major pathway for gas charging. With the increase of charging pressure, movable water in the edges of large-sized pores and in the centers of small pores is displaced out successively. Pore-throats of 20-50 μm in radius and pore-throats less than 20 μm in radius dominate the expansion of gas charging channels at different stages of charging in turn, leading to reductions in pore-throat radius, throat length and coordination number of the pathway, which is the main increase stage of gas permeability and gas saturation. Among which, pore-throats 30-50 μm in radius control the increase pattern of gas saturation. In the stable stage, gas charging pathways have expanded to the maximum, so the pathways keep stable in pore-throat radius, throat length, and coordination number, and irreducible water remains in the pore system, the gas phase is in concentrated clusters, while the water phase is in the form of dispersed thin film, and the gas saturation and gas permeability tend stable. Connected pore-throats less than 20 μm in radius control the expansion limit of the charging pathways, the formation of stable gas-water distribution, and the maximum gas saturation. The heterogeneity of connected pore-throats affects the dynamic variations of gas phase charging and gas-water distribution. It can be concluded that the pore-throat configuration and heterogeneity of the micro-nanometer pore system control the dynamic variations of the low-permeability(tight) sandstone gas charging process and gas-water distribution features.

集成PHAST-Visual Studio的岩溶区燃气管道灾害后果定量分析及应用

为科学评估岩溶区燃气管道灾害的后果影响程度,基于管道失效特征确定喷射火和蒸气云爆炸两种典型后果模式,研判适用于岩溶区燃气管道灾害的热辐射和冲击波超压危害准则,从危害面积、伤亡人数、经济损失、环境破坏4个维度提出岩溶区燃气管道灾害后果严重程度的评估模型体系,并结合Visual Studio平台开发“岩溶区燃气管道灾害后果分析软件”。立足岩溶区实际工程案例,结合区域经济社会发展、岩溶自然地质以及燃气管道工程特征,基于PHAST软件仿真分析灾害后果的影响范围,结合危害准则对区内人员、物体提出针对性灾害风险管控措施,并通过引入政府、行业、企业等颁布的标准条例,量化得出灾害后果的影响程度。结果表明:提出的PHAST-Visual Studio集成方法能够弥补以往研究的评估主观性问题,将社会科学思想带入工程风险评价研究,并通过计算机软件编程提高灾害后果分析效率,从而有助于显著控制岩溶区燃气管道灾害后果水平。

Analyses and Simulation of Fuzzy Logic Control for Suspension System of a Track Vehicle

The vibration caused by terrible road excitation affects the ride quality and safety of track vehicles. The vibration control of suspension systems is a very important factor for modern track vehicles. A fuzzy logic control for suspension system of a track vehicle is presented. A mechanical model and a system of difft, rential equations of motion taking account of the mass of loading wheel are established. Then the fuzzy logic control is applied to control the vibration of suspension system of track vehicles for sine signal and random road surfaces. Numerical simulation shows that the maximum acceleration of suspension system can be reduced to 44 % of the original value for sine signal road surface, and the mean square root of acceleration of suspension system can be reduced to 21% for random road surface. Therefore, the proposed fuzzy logic control is an efficient method for the suspension systems of track vehicles.

Development of driver-vehicle-road closed-loop semi-physical simulation system

As hybrid vehicles introduced the motor, the vehicle structure has a significant change in the power matching. A driver-vehicle-road closed-loop semi-physical simulation system, which makes real driving parts together with the simulation car, will bring convenience to the new car design. We used the computer software to simulate the road with a slope, curve and some other features based on the actual road condition, and analyzed the whole road scene in addition to geometry and physical characteristics. Analyzing and constructing the vehicle dynamics basic template, appropriate changes to the template can obtain the desired vehicle dynamics model with an external device to control the model vehicle. It combined the physical operation system with visual display, which gave us real driving feelings and increased the vehicle design predictive accuracy.

Design of an Integrated SITL and HITL Simulation System for the Control of a Loitering Aerial Vehicle

An investigation into the aircraft flight simulation and control system is presented in this paper. The study was firstly focused on the establishment of an integrated hardware-in-the-loop（HITL） platform for aircraft flight simulation based on MATLAB/Simulink ＋ dSPACE. The platform combines the abundant software and hardware resources of dSPACE simulation platform to simulate the flight attitude of an aircraft in six-DOF （ degree of freedom） motion. Based on the platform, the study was then focused on the flight numerical simulation by taking a loitering aerial vehicle as an example. An aircraft mathematical model was created for a modular design and off-line numerical simulation based on MATLAB/Simulink. Finally, the study was focused on the control system design of the loitering aerial vehicle and conduct of an HITL simulation experiment for the vehicle pitch control. The experiment verifies the system design and control effectiveness. Research results show that the dSPACE simulation system provides a real time good experimental platform to improve the efficiency of study and development of a flight control system.

Visual Modflow在和田县农业经济新区地下水资源评价中的应用

为全面了解地下水系统受各种激励因素影响后的水动力场和地下水量变化规律,以及为当地地下水资源开发与利用提供科学的指导意见,本次在和田县农业经济新区地下水资源评价中采用可视化标准软件Visnal Modflow实现地下水资源的模拟与预报,通过构建三维非稳定流数值模型,使用迭代方法求解,并根据设计开采量对地下水水位变动做出预测,再基于建模预测结果,结合经济新区地下水资源量确定合理的地下水开采量。

Simulation and visualization experiment of manganese ion diffusion and damage to gel in a porous media-gel system

A new visualization method for studying the damage to gel structure caused by high salinity ions is explored by using the characteristics of suppression image signal of Mn^(2+) and nuclear magnetic resonance(NMR) imaging technique. The diffusion and distribution characteristics of Mn^(2+) in porous media-gel system were studied based on manganese chloride static diffusion and gel flooding experiments, and the gel's nuclear magnetic image and displacement pressure were tested. The results show that the diffusion of Mn^(2+)conforms to the Fick diffusion law in porous media-gel system, and the diffusion speed of Mn^(2+) increases and the area of gel image decreases gradually with the increase of concentration, and the image of gel decreases faster and the pressure drop of water drive is larger in flooding experiment of manganese chloride with higher concentration. Reaction-diffusion model with the reaction of Mn^(2+) with gel was established to study the concentration distribution characteristics of Mn^(2+). The model is validated by comparing the results with magnetic resonance imaging(MRI) experiments and the diffusion coefficient of Mn^(2+) equals 1.6 mm^2/h, and the minimum concentration of Mn^(2+) to impact gel NMR image signals is 2.5 g/L. The above results show that the diffusion of Mn^(2+) into the gel in the rock core inhibits the imaging signal of the gel and damages its strength, and the greater the concentration is, the greater the influence. Increase of adsorption amount of gel and reaction rate, reduction of diffusion time, and addition of ion adsorption isolator all can reduce the impact of Mn^(2+) on the gel.

基于Visual MODFLOW的天化试剂一厂地下水污染物扩散数值分析

为了给城市污染场地的修复和治理提供依据,以天津市化学试剂一厂地块修复项目为例,利用三维模拟软件Visual MODFLOW建立地下水水流概念模型和溶质迁移模型,对风险管控区内氯乙烯等三种污染物进行20年的运移扩散数值模拟预测,并对其运移过程和分布特征进行分析。结果表明:污染物的运移除了自身的衰减、弥散和吸附等作用外,主要受地下水运动趋势的影响,随着地下水的流向进行扩散,受止水帷幕阻隔的影响,污染物在迁移扩散过程中发生了明显的“绕流现象”。垂直渗透系数较小的相对隔水层对污染晕的垂直扩散阻隔作用明显,浅部含水层中污染物浓度梯度随深度的增加而明显减小。三种污染物浓度均明显低于修复目标控制值。利用Visual MODFLOW建立地下水数值模型,可以预测污染物因子时空分布,定性的分析各种污染物的运移规律。

Application of Modelica Based Multi- Domain Modeling and Simulation for Gravity-1

In the R&D phase of Gravity-1(YL-1), a multi-domain modeling and simulation technology based on Modelica language was introduced, which was a recent attempt in the practice of modeling and simulation method for launch vehicles in China. It realizes a complex coupling model within a unified model for different domains, so that technologists can work on one model. It ensured the success of YL-1 first launch mission, supports rapid iteration, full validation, and tight design collaboration.

AB095. Development of an assessment system of driver visual behaviours on a car simulator

Background:(I)To describe the development and components of the automobile simulator driving behavior evaluation system developed by CRIR-Institut Nazareth et Louis-Braille;(II)to present the preliminary results of the content evaluation of the driving behavior evaluation grid.Methods:The evaluation system consists of five components:(I)the VS500M Car Simulator(Virage Simulation);(II)four VS500M driving scenarios,modified to minimize the occurrence of simulator sickness and expose subjects to commonly encountered driving situations on highways and city boulevards;(III)the Tobii Pro Glasses 2 eye tracking device;(IV)a car simulator driving behavior observation grid(DBOG);(V)a software application used during the behaviour evaluation phase,where synchronized video tracking,certain data from the simulator(e.g.,speed)and the DBOG grid are presented.Initially,the expected safe driving behaviors were identified,including 235 of a visual nature,supported by literature data and consultation of the project steering committee and an expert in driving assessment.Driving behaviors were assessed in 22 subjects without visual impairment(mean age 55±20 years).Subsequently,the items were revised to determine their relevance based on their importance in terms of road safety or on the frequency with which behaviors were observed among participants.For analysis purpose,the items of the DBOG were grouped according to their content,by type of expected driving behavior(e.g.,following a stop,look to the left and right before crossing the intersection)or element to be detected(e.g.,pedestrians).Results:Some visual behaviors are difficult to observe with the eye tracker device because they are more dependent on peripheral than central vision.Others are rarely observed,possibly because they are little or not realized in daily life or the representation of reality on the simulator does not stimulate their adoption.On the other hand,the visual detection behaviors expected in a situation where safety can be compromised are mostly carried out(e.g.,detection of oncoming vehicles,side mirror verification when changing lanes).Conclusions:This first phase of the study has made possible to better target the items to be kept in the car simulator driving behavior observation grid,and those that will have to be removed as they are too difficult to observe or too rarely adopted by the participants.Content validity and inter-rater reliability will be assessed from the simplified grid.

Design and Implementation of One Missile Visual Simulation System Based on OpenGL

The implementation of a missile's visual simulation system is explained that is developed with OpenGL(open graphic library) and the flight path and flight carriage in different stages of the missile are displayed. The establishment problems of the 3D scene are circumstantiated including the construction and redeployment of the model, creation of the virtual scene, setting of the multi-viewports and multi-windows etc. The missile's data driver, system flow, the modules and their mutual relations of the missile visual simulation system are discussed. The missile flight simulation results and effect of the scenes are given.

Simulation platform of navigation system for autonomous underwater vehicle

In view of the characteristics of underwater navigation, the simulation platform of navigation system for autonomous underwater vehicle has been developed based on Windows platform. The system architecture, net communication and the information flow are discussed. The methods of software realization and some key techniques of the Vehicle Computer and the Navigation Equipment Computer are introduced in particular. The software design of Terrain Matching Computer is introduced also. The simulation platform is verified and analyzed through simulation. The results show that the architecture of the platform is reasonable and reliable, and the mathematic models and simulation algorithms of sub-systems are also valid and practicable.

基于Visual MODFLOW的红层地区某钛白粉厂地下水污染物运移模拟研究

数值模拟技术是保护地下水环境的有效方法,但实际中获取准确的水文地质参数难度较大,如何准确获取参数成为数值模拟技术应用成败的关键。基于该关键问题,本文以广西某钛白粉厂为例,在查明水文地质特征基础上,应用Visual MODFLOW软件建立地下水流数学模型和溶质运移模型。选取钛白粉厂主要污染物COD、氨氮和氟化物作为预测因子,预测其在地下水中运移情况。结果反映钛白粉厂污水处理车间和污水调节池发生渗漏未对下游地谷岭造成影响。本次模拟的预测结果对该区地下水的保护有着重要意义。