An Effective 3D-CFD Methodology for the Complementary Virtual Development of Alternative Fuels and Engine Concepts

With the aim of reducing the cost of developing internal combustion engines,while at the same time investigating different geometries,layouts and fuels,3D-CFD-CHT simulations represent an indispensable part for the development of new technologies.These tools are increasingly used by manufacturers,as a screening process before building the first prototype.This paper presents an innovative methodology for virtual engine development.The 3D-CFD tool QuickSim,developed at FKFS,allows both a significant reduction in computation time and an extension of the simulated domain for complete engine systems.This is possible thanks to a combination of coarse meshes and self-developed internal combustion engine models,which simultaneously ensure high predictability.The present work demonstrates the capabilities of this innovative methodology for the design and optimization of different engines and fuels with the goal of achieving the highest possible combustion efficiencies and pollutant reductions.The analysis focuses on the influence of different fuels such as hydrogen,methanol,synthetic gasolines and methane on different engine geometries,in combination with suitable injection and ignition systems,including passive and active pre-chambers.Lean operations as well as knock reduction are discussed,particularly for methane and hydrogen injection.Finally,it is shown how depending on the chosen fuel,an appropriate ad-hoc engine layout can be designed to increase the indicated efficiency of the respective engines.

OPTIMIZATION METHOD FOR VIRTUAL PRODUCT DEVELOPMENT BASED ON SIMULATION METAMODEL AND ITS APPLICATION

Virtual product development (VPD) is essentially based on simulation. Due tocomputational inefficiency, traditional engineering simulation software and optimization methods areinadequate to analyze optimization problems in VPD. Optimization method based on simulationmetamodel for virtual product development is proposed to satisfy the needs of complex optimaldesigns driven by VPD. This method extends the current design of experiments (DOE) by variousmetamodeling technologies. Simulation metamodels are built to approximate detailed simulation codes,so as to provide link between optimization and simulation, or serve as a bridge for simulationsoftware integration among different domains. An example of optimal design for composite materialstructure is used to demonstrate the newly introduced method.

Virtual Reality and Visual Simulation Technology in Platform Construction with Four Bucket Foundations Based on Secondary Development of Vega

The platform with bucket foundations can penetrate and migrate by underpressure/positive pressure technique caused by pumping water out/in the bucket. However, the construction process of bucket foundations cannot be clearly observed and effectively controlled due to the special nature of sea environment. By using an advanced simulation development tool of Multigen Creator, the visual construction simulation program for the platform with bucket foundations was developed to set up the virtual reality system with interaction control and observation in every view angle based on the secondary development technology of Vega platform. The application results show that the method is feasible and effective by simulating the whole construction process for the platform with four bucket foundations.

RESEARCH ON PRODUCT INNOVATION DESIGN IN VIRTUAL PRODUCT DEVELOPMENT

An integrated template of virtual product development alters primarilysequential tradition mode of product life cycle. The template integrates all processes of productdevelopment using digital modem. An environment of virtual product development provides productdevelopment environment of integration, communion, network, concurrent and collaboration. Combiningdevelopment of new rapier loom, an innovated design process is researched in virtual productdevelopment, which consists three portions: constructing an integration development environment,innovation design and manufacturing simulation. The innovated design process realizes reversedesign, mechanism concept design, structural design and analysis, performance analysis andmanufacturing process simulation of virtual product, which can enhance greatly product performanceand reduce cost and development cycle of new product.

Research on Design Optimization Strategy in Virtual Product Development

Simulation and optimization are the key points of virtual product development (VPD). Traditional engineering simulation software and optimization methods are inadequate to analyze the optimization problems because of its computational inefficiency. A systematic design optimization strategy by using statistical methods and mathematical optimization technologies is proposed. This method extends the design of experiments (DOE) and the simulation metamodel technologies. Metamodels are built to in place of detailed simulation codes based on effectively DOE, and then be linked to optimization routines for fast analysis, or serve as a bridge for integrating simulation software across different domains. A design optimization of composite material structure is used to demonstrate the newly introduced methodology.

Comparison of Developmental Stages in Relation to Way Finding Behavior in an Immersive Virtual Reality Space

To establish a proper evaluation method for spatial cognitive deficits and a form of developmental disorder, we have used an immersive virtual reality (VR) device to develop a game that involves actually walking through a VR space to search for a target object. In this paper, we presented the results of control experiment with 22 healthy elementary school students as participants. The complexity of the VR space was controlled according to the number of pillars present and whether an overall view was possible (controlled by the height of the pillars). For each set of conditions, 24 trials were performed, and the route and time taken to search for the target were recorded. The starting point was changed in each subsequent trial. Results showed that the search time decreased as the number of trials increase, suggesting a process whereby a cognitive map was formed. We also compared the present results to results from our previous experiment with university students using the same experimental conditions, and we discussed the influence of developmental stage on spatial cognition.

VIRTUAL FUEL-PUMP DESIGN

Some concepts of virtual product are discussed. The key technologies ofvirtual fuel-pump development are in detail analysed, which include virtual fuel-pump productmodeling, intelligent simulation, distributed design environment, and virtual assembly. The virtualfuel-pump development prototype system considers requirement analysis, concept design, injectionpreferment analysis, detailed design, and assembly analysis.

基于ARM的嵌入式虚拟开发平台

为了解决目前大部份高校缺乏嵌入式开发平台的问题,提出了构建嵌入式虚拟开发平台方案。方案采用μVi-sion4 IDE和Proteus进行整合,在不需要购置嵌入式硬件设备的情况下,通过改造、整合原有实验设备,实现具有嵌入式系统设计、开发等软、硬件同步仿真调试功能的嵌入式虚拟实验室。同时给出了具体的教学模式革新和实施方法。

基于Web的数字化参考咨询服务

本文介绍了数字化参考咨询服务的特点、传统参考咨询服务的异同和主要应用技术,并提出了虚拟参考咨询服务的发展趋势。

中小企业发展战略制定的原则和重要性分析

在市场竞争中,中小企业如果仅依赖自身资源是无法与大企业相抗衡的,在竞争中也相对处于劣势,但是,将市场资源进行有力整合,制定发展战略,并及时调整,形成全新的思维和战略发展模式,可使中小企业在市场竞争中获得优势。对中小企业发展战略制定的原则进行梳理,重点阐述虚拟经营原则,并分析了发展战略在企业管理和发展中的重要性。

基于MRI的有限元建模和分析在髋臼周围截骨术中的应用

髋臼周围截骨术(PAO)是一种矫正发育性髋关节发育不良(DDH)髋臼方向的手术方法.本文基于DDH患者的髋关节磁共振成像(MRI)数据,构建有限元模型,进行PAO虚拟手术规划研究.通过计算髋臼从原始中心边缘(CE)角以5°增量变化旋转时,骨盆和股骨软骨间的峰值接触压力和接触面积,确定PAO中髋臼的最佳位置.此外,我们进一步利用有限元分析对术前和获得最佳位置的计划模型进行6个方向的模拟运动,并对所有方案的术前模型和计划模型进行了比较.分析结果表明,该患者髋臼最佳手术位置在CE角为20°时,且在髋关节运动过程中,计划模型中的峰值接触压力均低于术前模型,接触面积均大于术前模型,从生物力学的角度验证了虚拟手术规划的有效性.

术前三维可视化虚拟在发育性髋关节发育不良手术中的临床价值

目的术前三维可视化虚拟在发育性髋关节发育不良手术中的临床价值。方法根据术前是否行三维可视化虚拟将发育性髋关节发育不良患者分为观察组和对照组,比较两组患者治疗后疗效、手术时间、术中出血量、住院时间和患者满意率的差异。结果观察组发育性髋关节发育不良患者手术时间、术中出血量、住院时间均显著低于对照组(P<0.05)。满意率和Harris髋关节功能评分优良率均显著高于对照组(P<0.05)。结论术前三维可视化虚拟可提高发育性髋关节发育不良患者手术疗效,减少手术时间、术中出血量和住院时间,值得在临床上广泛应用。

Influence of physical data and cooling conditions on the solidification of magnesium die castings

As the simulation quality increases, the determination of hot spots is not enough to foundry engineers anymore. The simulation results have to fit in a quality way into the real foundry world. More and more results of the simulation will be used to optimise the casting process. Here it is necessary to have a very precise knowledge of the physical data. as well as the description of the geometry. To make use of the simulation in especially the magnesium-casting development it is necessary to work with precise geometrical, physical and numerical models. In this paper we describe the development of physical data concerning the heat transfer during filling and solidification by different casting methods. The low pressure as well as the gravity die casting method are used to get real data to find out the right conditions in the simulation in order to simulate the real behaviour during production. Practical tests are done under different test conditions to develop the right physical data as well as the right conditions in the metal-mould interface. The different surface conditions and the influence of the die and the molten metal temperatures are important for the layout of the die casting process. Three different shapes were applied to different mould materials and casting methods. The cooling conditions are tested on specific items. The cooling shape is not restricted by the drilling conditions. The effect of different cooling conditions are generated and measured. The results form the basis for the heat transfer conditions. These results are applied to real castings, cellular phone housings by low-pressure die casting process. The use of the new conditions leads to a good process description.

三维可视化虚拟对发育性髋关节发育不良手术治疗患者髋关节功能的影响

目的:研究三维可视化虚拟对发育性髋关节发育不良手术治疗患者髋关节功能的影响。方法:选取66例发育性髋关节发育不良手术治疗患者作为研究对象,随机分为试验组与对照组,每组33例患者,给予对照组患者常规手术前辅助CT和X线定位处理,从二维平面评价患者的实际情况;试验组患者手术前在传统CT和X线基础上,应用三维可视化重建技术,建立三维可视化立体模型,并虚拟患者的手术过程,对比两组患者的治疗效果、Harris髋关节功能评分、疼痛视觉模拟评分(VAS)、独立行走和辅助行走的情况以及生活质量评分。结果:对照组患者总有效率72.72%,试验组患者总有效率为93.94%,试验组显著高于对照组,差异有统计学意义(P<0.05);试验组患者手术后Harris髋关节功能评分明显优于对照组,差异有统计学意义(P<0.05);试验组VAS明显高于对照组,差异有统计学意义(P<0.05);试验组独立行走患者人数明显高于对照组,差异有统计学意义(P<0.05);试验组的整体健康水平、身体创伤和生理功能指标评分明显优于对照组,差异有统计学意义(P<0.05);两组患者手术后生命力和生理功能指标评分比较,差异无统计学意义(P>0.05)。结论:传统手术辅助方式与三维可视化虚拟对发育性髋关节发育不良手术的患者治疗均有效果,但利用三维可视化虚拟对患者的治疗效果更明显,疼痛感小,髋关节功能恢复更好,能够提升患者的生活质量。

三维神经元几何形态的发育生成方法

生物神经细胞具有复杂多样的空间几何形态,而这种形态结构是研究单个神经细胞信息处理和整个神经系统连接的基础。为此,提出一种针对三维神经元几何形态的发育生成方法。采用人工基因组对基因调控网络进行编码,用基因表达的动态特性来表示神经元树突树的发育过程。实验结果表明,生成的虚拟神经元与实际神经元具有相似的几何形态结构。与已有基于发育机制的生长方法相比,更真实地表现了生物神经元的发育过程。与基于统计分析的重建方法相比,能够更方便地得到几何形态参数的统计分布函数。

虚拟现实技术辅助儿童发育性髋脱位Salter截骨术

[目的]介绍虚拟现实技术辅助儿童发育性髋脱位(developmental dislocation of the hip,DDH)Salter截骨术的技术与初步临床结果。[方法]对46例(46髋)DDH患儿术前进行计算机虚拟现实辅助Salter截骨术。术前CT扫描建立虚拟髋关节模型,模拟Salter截骨术,观察手术效果,确认股骨头包容良好,实际手术中按模拟手术测量参数进行操作。行患侧Bikini切口,沿着髂嵴软骨外缘近端切开,清理髋臼,剥离髂骨,经股骨近端外侧做股骨转子间截骨,按照术前模拟确定的髋臼最佳旋转角旋转插入合适的自体或异体骨块,克氏针固定后复位髋臼,修剪关节囊,逐层缝合。[结果]患儿均顺利完成手术,手术时间(52.33±7.52)min,术中失血量(45.35±5.01)ml,术后住院(7.20±1.55)d;术中及术后无严重并发症。患儿术后随访6~18个月,平均(10.35±3.01)个月,末次随访时,所以患儿均可自行下地活动,McKay功能评价优良率为100%。影像方面,虚拟手术与真实手术后髋臼指数(acetabular index,AI)、中心边缘角(centre-edge,CE)、前倾角均显著低于术前相应参数(P<0.05)。虚拟手术与真实手术后的AI、CE角、前倾角差异无统计学意义(P>0.05)。[结论]采用虚拟现实技术辅助Salter截骨术可提升治疗儿童DDH的精准性。