森林场景可视化和林火模拟仿真技术研究综述

森林是生态环境系统的重要组成部分。随着气候变暖,恶劣气候气象条件造成全球森林火灾频繁发生,给国民经济和消防救援带来巨大挑战,森林火灾已成为全球主要的自然灾害。因此,森林场景可视化建模、3维场景仿真、林火模拟仿真、火场复现、预测和灾害评估成为林业虚拟仿真研究热点。本文对树木形态结构建模技术、森林场景大规模重建和实时渲染、森林场景可视化、林火模型和林火模拟仿真等前沿技术和算法进行综述。对相关的林木、植被的形态结构表达和真实感可视化建模方法进行归纳分类,并对不同可视化方法的算法优劣、复杂度、实时渲染效率和适用场景进行讨论。基于规则的林木建模方法和基于林分特征的真实场景重建方法对大规模森林场景重建技术进行分类,基于物理模型、经验模型和半经验模型对森林火灾的林火模型、单木林火、多木林火模拟和蔓延进行总结,对影响林火蔓延的不同环境气象因子（如地形地貌、湿度、可燃物等）和森林分布对林火发生、扩散和蔓延的影响进行分析,对不同算法的优劣进行对比、分析和讨论,对森林场景可视化和林火模拟仿真技术未来的发展方向、存在问题和挑战进行展望。本文为基于森林真实场景的森林火灾模拟仿真和数字孪生沉浸式互动模拟系统的构建提供了理论方法基础,该平台可以实现森林场景快速构建、不同火源林火模拟、火场蔓延模拟仿真以及不同气象影响条件的火场预测,可对森林火场救援指挥、火场灾害评估和火场复原提供可视化决策支持。     

基于主变起火应急演练的虚拟现实培训系统

为提高火灾应急演练的训练能力,提出基于主变起火应急演练的虚拟现实培训方法。在3D虚拟现实视景模型下计算起火环境的单尺度特征参数,并根据参数结果构建图像输出模型,结合主变起火应急演练模糊控制方法进行虚拟现实培训的三维重构,实现主变起火应急演练虚拟现实培训的控制,在虚拟现实系统中进行主变起火应急演练的视景重构,在视点位置中进行主变起火应急演练的3D虚拟现实模拟,实现基于主变起火应急演练的虚拟现实培训设计。仿真结果表明,采用该方法进行虚拟现实培训系统设计的帧渲染速度快、特征配准率高。     

基于数字地球的林火灾害建模

针对数字地球上林火灾害可视化问题,建立林火灾害仿真可视化框架。设计蔓延表现算法,采用Rothermel火行为计算模型和邻接单元蔓延模型。提出一种网格均匀划分的简化模型,进行仿真实验。结果表明,该方法能在数字地球上表达林火蔓延过程,较好地描述林火蔓延物理机理,为三维地理环境上的灾害分析提供辅助支持。     

毫米波MIMO系统离散化混合预编码设计

为了提高毫米波大规模多输入多输出（MIMO）系统波束成形增益,降低天线与移相器的硬件成本,提出一种基于离散移相器的混合预编码设计方案。以最优化频谱效率为目标,该方案通过分析均匀直线阵列与均匀平面阵列的响应矢量,将毫米波信道的空间特性预编码的设计考虑为空间稀疏重构问题,采用离散化正交匹配追踪原理求出数字预编码与离散化的模拟预编码。仿真结果表明,同等条件下平面阵列的频谱效率优于直线阵列,同时所提出的离散化混合预编码方案中低精度移相器的性能近乎达到全精度移相器的性能增益。     

基于多人协同虚拟现实的主变应急培训应用研究

为了提高主变应急培训能力,提出基于多人协同虚拟现实的主变应急培训视景仿真模型.以火灾应急演练为研究对象,构建主变应急培训的虚拟视景图像重构模型,并对虚拟视景环境参数进行结算,根据参数结果的计算,进行主变应急培训过程中的虚拟现实仿真,实现主变应急培训的虚拟现实VR仿真模型的优化设计.测试结果表明,采用该方法进行主变应急培训的虚拟视景仿真的协同性较好,图像融合性能较高,视景重构能力较强.     

基于多智能体的森林火灾人员疏散仿真

森林火灾发生时, 对在林火蔓延过程中灾区人员疏散进行建模与仿真能够检查疏散方案是否合理, 从而为合理救灾提供指导意义. 目前对人员疏散模拟与仿真虽然有很多研究, 但对于森林火灾下人员疏散尚缺乏合适的仿真模型, 给科学救助决策带来很大困难. 为此, 提出将多智能体引入森林火灾蔓延及灾区人员疏散模型研究中, 并借助于Repast平台进行仿真, 实验结果表明本文方法能够为森林火灾人员疏散模拟与仿真提供正确的解决途径.     

车辆碰撞事故再现技术的发展

事故再现技术是鉴定事故责任和分析事故原因的方法之一。通过对国内外车辆碰撞事故再现技术的回顾，总结了车辆碰撞交通事故再现技术的一般仿真算法计算流程，探讨了事故再现技术中影响仿真速度和精度的主要原因，其中估计车辆的初始碰撞位置参数进行迭代计算将导致较长的计算时间，忽略车辆的塑性变形和驾驶员的操纵行为将导致模型的不精确。展望了事故再现技术的发展趋势，未来的交通事故再现技术将能够推断驾驶员的操纵行为，模拟出驾驶员的生理心理变化，并能进行事故预防分析。     

A simulation approach for estimating flank wear and material removal rate in turning of Inconel 718

The present work attempts to study the effect of important machining variables on performance characteristics such as material removal rate and tool wear in turning of Inconel 718 using chemical vapour deposition (CVD) coated tungsten carbide (WC) tool. A three dimensional machining model using Lagrangian approach has been developed using DEFORM 3D. The machining simulation is carried out to predict the flank wear and material removal rate (MRR). Flank wear is calculated using Usui’s wear model in the simulation model. The results from simulation model are compared with experimental data generated by the use of Taguchi’s L₁₆ orthogonal array for reducing the experimental runs. Analysis of variance (ANOVA) is performed to identify the most influencing variables for both the performance characteristics. It is found that simulation results are in good agreement with experimental results. A valid simulation models helps the tool engineers to gather relevant process related information without resorting to costly and time consuming experimentation.     

基于多尺度投影的相似颅骨检索

在基于模板变形的颅面复原方法中,复原的开始阶段需要在数据库中选取与待复原颅骨最为相似的参考颅骨.鉴于基于三维模型的检索算法时间久且颅骨间的差异细微,从而不同于一般三维模型数据库中各模型的差异.因此,已有的三维模型检索算法不适用于颅骨检索.本文提出一种夹角信息和距离信息融合的颅骨轮廓特征提取算法,并在此基础上提出一种能够反映颅骨空域信息的剖面特征提取算法.检索时首先获取三维颅骨的正交投影和深度投影,通过正交投影获取轮廓的角度和距离特征,通过深度投影获得具有空域信息的剖面特征;然后对多个特征进行加权融合搜索到最相似颅骨;最后通过ICP+TPS对检索到的颅骨进行误差评估.实验表明,本算法在保证检索效率的同时,可以准确地应用在颅面复原前期对最相似颅骨的选择上.     

Integrating fire spread patterns in fire modelling at landscape scale

Fire spread modelling in landscape fire succession models needs to improve to handle uncertainty under global change processes and the resulting impact on forest systems. Linking fire spread patterns to synoptic-scale weather situations are a promising approach to simulating fire spread without fine-grained weather data. Here we present MedSpread—a model that evaluates the weights of five landscape factors in fire spread performance. We readjusted the factor weights for convective, topography-driven and wind-driven fires (n = 123) and re-assessed each fire spread group's performance against seven other control simulations. Results show that for each of the three fire spread patterns, some landscape factors exert a higher influence on fire spread simulation than others. We also found strong evidence that separating fires by fire spread pattern improves model performances. This study shows a promising link between relevant fire weather information, fire spread and fire regime simulation under global change processes.     

Optimization of optical design for developing an LED lens module

In this study, a procedure for optimization of an LED lens module design based on 3 LED light sources was divided into two phases. For preliminary optimization of the dimensions of the LED lens module in Stage I, an optical analysis with orthogonal arrays and TracePro (an optical design package) combined with analysis of variance was conducted to investigate relationships between the multiple optical quality characteristics (viewing angle and average illuminance) and dimension parameters and find the initial optimal parameter combination of the LED lens module. In Stage II, the initial optimal parameter combination determined in Stage I was employed to develop an orthogonal array L₂₅(5⁶) for optical simulation. The experimental data of the orthogonal array were used to train and test the back-propagation neural network to develop an optical quality predictor, which was integrated into the genetic algorithms and the particle swarm optimization in order to find the optimal parameter combination that conformed to optical quality. From the experimental results, the proposed optimization procedure contributes to a precise viewing angle to achieve the goal of optical quality and improved the average illuminance in development of the product. The procedure to optimize the optical design developed in this study can be applied to design all types of LED lens modules and improve the optical design and technology of the LED lens industry.     

The use of the Taguchi method with grey relational analysis to optimize the thin-film sputtering process with multiple quality characteristic in color filter manufacturing

The paper proposes an approach to improve the yield of Chrome (Cr) thin-film sputtering process of the black matrix (BM) in color filter manufacturing and to find the robust parameters of the process with multiple quality characteristics by using the Taguchi method combined with the grey relational analysis. The research considers the correlation between quality characteristics and applies the principal component analysis to eliminate the multiple co-linearity. The weights of the quality characteristics are determined by employing the entropy measurement method. Two quality characteristics and four control factors with three levels were selected. Based on the Taguchi quality design concept, a L9 orthogonal array table was chosen for the experiments. The confirmation experiment verifies the proposed grey-based Taguchi method has the ability to find out the optimal process parameters with multiple quality characteristics. Besides, manufacturing with the attained optimal process parameters can reduce the opportunities of repair and rework of Cr thin-film and raise the yield.     

油气储罐火灾爆炸风险模拟评估方法研究及软件系统开发

油气储罐由于固有的火灾和爆炸危险性,一旦发生泄漏会导致火灾和爆炸事故的发生,因此研究油气储罐的风险评估方法对于预防和控制事故的发生具有十分重要的意义.随着计算机技术的发展,运用计算机模拟技术模拟危险化学品储罐事故后果,以及对环境的危害过程成为可能.针对油气储罐的火灾爆炸特性,在对现有各种火灾爆炸损伤模型总结分析的基础上,对几种常见事故选择和确定了其模拟数学模型,并开发了火灾爆炸事故评估的软件系统,详细介绍软件系统的功能和组成框架.软件系统由储罐危险源识别系统、火灾爆炸分析评估系统、油气储罐事故预防和控制训练系统和数据库系统组成.该系统可以对事故后果包括危险区域、人员伤害范围、经济损失等进行量化计算和分级,通过对模拟结果的分析与比较可以得剑火灾爆炸事故的等级,软件系统可以完成风险评估,从而大大提高了评估的效率和科学性.     

The simulation and optimization integration calculation method and application validation for the traffic accident

In the tradition traffic accident simulation method, the main parameters need to be determined by experience. If there is any problem found in the simulation process, we will have to change the model by amending input parameters and re-start the simulation. Therefore, the accident reconstruction result has very big difference with real accident process. This article discusses the coupled calculation method between the traffic accident simulation and simulation optimization. Then it confirms the method’s validity through the reliability analysis to simulation result. Finally through the actual traffic accident cases’ simulation and optimization analysis, the reconstruction result shows that the deviation of the accident reconstruction result does not exceed 10%. And the reconstruction result is a nice match with the accident scene investigation data. The simulation and optimization integration calculation method provides an effective solution to the problem that lies in traditional traffic accident simulation.     

基于数值仿真的人车碰撞事故再现研究

对于对未留制动印迹的人车碰撞事故采用数值仿真方法进行再现研究,提出了通过调整碰撞车速使得仿真结果(人体抛距、人体损伤情况等)逼近真实事故结果的方法估计碰撞车速,并应用于一起真实事故的再现研究,初步验证了模型和方法的可行性.采用上述经过验证的数值模型研究人车碰撞初始条件对仿真结果的影响发现:人车相对接触位置接近汽车前部一侧时对人体抛距值的影响较大,因此单纯根据人体抛距估计碰撞车速可能会造成再现结果的失真.     

Multi-Scale Adaptive Sampling with Mobile Agents for Mapping of Forest Fires

The use of robotics in distributed monitoring applications requires wireless sensors that are deployed efficiently. A very important aspect of sensor deployment includes positioning them for sampling at locations most likely to yield information about the spatio-temporal field of interest, for instance, the spread of a forest fire. In this paper, we use mobile robots (agents) that estimate the time-varying spread of wildfires using a distributed multi-scale adaptive sampling strategy. The proposed parametric sampling algorithm, “EKF-NN-GAS” is based on neural networks, the extended Kalman filter (EKF), and greedy heuristics. It combines measurements arriving at different times, taken at different scale lengths, such as from ground, airborne, and spaceborne observation platforms. One of the advantages of our algorithm is the ability to incorporate robot localization uncertainty in addition to sensor measurement and field parameter uncertainty into the same EKF model. We employ potential fields, generated naturally from the estimated fire field distribution, in order to generate fire-safe trajectories that could be used to rescue vehicles and personnel. The covariance of the EKF is used as a quantitative information measure for sampling locations most likely to yield optimal information about the sampled field distribution. Neural net training is used infrequently to generate initial low resolution estimates of the fire spread parameters. We present simulation and experimental results for reconstructing complex spatio-temporal forest fire fields “truth models”, approximated by radial basis function (RBF) parameterizations. When compared to a conventional raster scan approach, our algorithm shows a significant reduction in the time necessary to map the fire field.     

新的RoboCup救援仿真分区消防策略

在RoboCup救援仿真的消防策略中,火势蔓延的控制对救援的效果有着重要的作用。大多数队伍采用基于单个建筑的各种指标的单目标选择法,该方法在着火建筑较多或者火势蔓延快时难以对火势进行有效控制。提出一种新的基于密度聚类的分区方法,根据火势蔓延速度将所有建筑进行聚类分析形成建筑簇并分开成为不同的区域,然后综合建筑的属性作为权值选择目标区域和灭火建筑,从而有效地控制火灾的蔓延甚至将火灾完全扑灭。最后通过仿真实验和比赛验证了该方法的有效性。     

Efficient and scalable quicksort on a linear array with a reconfigurable pipelined bus system

Based on the current fiber optic technology, a new computational model, called a linear array with a reconfigurable pipelined abus system (LARPBS), is proposed in this paper. A parallel quicksort algorithm is implemented on the model, and its time complexity is analyzed. For a set of N numbers, the quicksort algorithm reported in this paper runs in O(log₂ N) average time on a linear array with a reconfigurable pipelined bus system of size N. If the number of processors available is reduced to P, where P < N, the algorithm runs in O((N/P) log₂ N) average time and is still scalable. Besides proposing a new algorithm on the model, some basic data movement operations involved in the algorithm are discussed. We believe that these operations can be used to design other parallel algorithms on the same model. Future research in this area is also identified in this paper.     

道路交通事故的三维仿真方法研究

在道路交通事故的再现分析当中，三维仿真属于最终的环节。利用碰撞模型和模拟模型分析计算出肇事车辆、人、畜在事故过程中各个时刻的运动形态，使用三维动画的形式再现事故的整个过程是三维再现方法研究的主要内容。该文根据CM碰撞模型和基于龙革库塔法的模拟模型的计算结果，使用OpenGL图形接口，实现了交通事故的三维仿真，并且利用VisualC 6．0开发工具开发了实用软件3D Player。     

An end-to-end generative network for environmental sound-based covert communication

Environmental sounds, everyday audio events that do not consist of music or speech data and are often more diverse and chaotic in their structure, have proven to be a promising type of carrier signals to carry out covert communication as they occur frequently in the natural environment, e.g., marine communication by mimicking dolphin or sea lion whistles. However, a mass collection of the carrier signals still remains a challenging task. Recently proposed generator models represented by Generator Adversarial Nets (GAN) have provided an effective way to synthesize environmental sounds. In this study, an end-to-end convolutional neural network (CNN) is proposed to directly transform the randomly sampled Gaussian noise into environmental sound that contains the secret message. The proposed network structure is composed of upsampling groups and orthogonal quantization layer, which can simultaneously realize factor analysis and information embedding. The design of the orthogonal quantization layer to complete the message embedding task is inspired by spread spectrum, model-based modulation, and compensative quantization. The underlying idea in this study is to treat the secret message as the constraint information in the generative model with the aim of maximizing the complete data model. The alternating back-propagation algorithm is used to train the overall network. Experimental results show that the proposed scheme can generate realistic environmental sounds that convey secret messages, while guaranteeing a high degree of communication reliability.