汽车碰撞时间特性的仿真

随着汽车向高速化方向发展,对汽车的安全性要求越来越高,汽车在高速下的碰撞特性研究也就显得非常重要。文中讨论了汽车碰撞时车体的加速度、速度和位移的变化情况,给出了用于仿真研究的碰撞参数模型,并对汽车正面碰撞时车体的时间特性（加速度、速度）进行了仿真分析。     

研究汽车碰撞中头颈部动态响应的有限元模型的建立和验证

建立并验证了一个基于人体解剖学结构的头颈部三维有限元模型．该模型由颅骨、脑、颈椎骨、椎间盘、肌肉、韧带和小关节组成,总节点数为17758,单元数21803,模型生物材料特性分别用弹性和粘弹性模型描述．整个头颈部模型应用关国海军生物力学实验室前碰撞志愿者实验及查尔摩斯大学后碰撞滑车实验的数据进行了验证．采用该模型计算了头颈部的加速度、角速度等运动曲线及HIC值．验证结果显示该模型具有较好的生物逼真度,可用于研究在汽车碰撞事故中头颈部损伤生物力学问题和开发损伤防护装置．     

汽车碰撞中胸-腹部的生物力学响应与损伤评价

统计表明,在汽车交通事故中人体胸部和腹部的损伤占很大的比例.为了研究汽车碰撞事故中人体胸腹部的生物力学响应与损伤机理,文中利用建立的人体胸-腹部生物力学有限元仿真模型,并引入国际同行已进行的相同部位尸体实验研究数据,对碰撞过程中人体胸腹部的生物力学响应进行了仿真分析.文献尸体实验与仿真过程中胸腹部的受力、加速度、胸腹部压缩变形量以及应力、应变分布等指标的对比结果表明,仿真结果与实验数据具有很好的一致性.研究表明,人体胸-腹部生物力学响应的有限元模拟能够准确地反应碰撞过程中人体胸-腹部的损伤程度,文中提出的模型可以用于汽车车身结构、约束系统、防护系统等方面的安全性设计和评估.     

后碰撞中乘员颈部肌肉有限元模型的建立与验证

建立并验证了具有主动力响应的乘员颈部肌肉有限元模型,用于研究颈部肌肉主被动响应对后碰撞载荷下乘员头颈部动力学响应及颈部损伤的影响.运用50百分位成年男性颈部的MRI数据重建了人体颈部肌肉三维数值模型,采用克里格插值方法将其与头颈基础模型进行匹配.肌肉材料定义采用Ogden材料和Hill材料相耦合的办法以分别模拟肌肉的被动和主动特性.根据Davidsson等人开展的后碰撞台车志愿者试验数据对该颈部肌肉模型进行了验证.结果表明,肌肉激活状态下与未激活时比较,头部质心相对T1位移减小了12mm,头部角位移减小了4°,肌肉主动力影响显著.该模型的数值模拟结果与志愿者试验结果吻合较好,模型具有较高的生物逼真度,可应用于后碰撞中的乘员颈部损伤研究.     

基于汽车碰撞事故的人体头部有限元模型建立与验证

为研究汽车碰撞事故中人体头部损伤机理,建立并验证具有较高生物逼真度的头部三维有限元模型.采用计算机断层扫描和磁共振相结合的医学成像技术,利用数字图像识别和网格剖分技术,获得50百分位人体头部有限元网格.通过碰撞仿真分析,得到撞击力、颅内加速度、颅内典型碰撞位置(碰撞侧、碰撞对侧、上下枕骨)的应力和压力变化规律,并与国外经典的尸体试验数据进行对比分析.仿真分析结果与试验中颅内压力、颅内运动学等生物力学参数吻合良好,能够准确反映真实碰撞过程中人体头部的生物力学响应情况.建立的头部三维有限元模型精确度较高,能够进一步应用于汽车碰撞事故中人体头部损伤力学机理研究.     

基于CT图像颈椎有限元模型的建立及验证

针对目前在颈部损伤机理的研究中尚未有适合中国人体型特点的全颈椎有限元模型的情况,采用CT技术获取中国50百分位人体颈椎数据,并以此建立了全颈椎有限元模型.模型采用映射网格划分方法对松质骨、椎间盘和韧带等结构进行了划分,利用现有的颈椎材料参数进行比例和功能缩放来定义稀缺的材料参数.整个模型共有22 512个实体单元,14 180个壳/膜单元,模型解剖结构描述细致、准确.最后通过颈椎离体坠落试验对模型的有效性进行验证,验证结果表明,该模型具有良好的生物逼真度,可应用于研究国人颈椎在汽车碰撞事故中的动态响应和损伤机理.     

高速公路中间带护栏碰撞仿真实验

针对高速公路中间带护栏安全性难以评估及实车碰撞护栏存在危险性等问题,提出了基于计算机仿真的高速公路中间带护栏碰撞安全性评估方法.建立了汽车模型、护栏模型、路缘石模型和碰撞模型,进行了多角度、不同速度和有无路缘石情况下的汽车碰撞仿真实验,并对碰撞数据进行了分析.结果表明:通过仿真实验可获得各种情况下汽车碰撞护栏的实验数据,为进行护栏安全性评估提供了依据;该方法具有参数容易修改、数据表达直观、实验速度快和节省费用等优点.     

中国人肋骨密质骨厚度的测定与特征分析

汽车碰撞事故中,肋骨密质骨厚度分布对肋骨骨折特性有显著影响,其形态学特征与人体参数等因素密切相关。该文定量描述了肋骨密质骨厚度分布,并分析了年龄、性别、身高和身高质量指数(BMI)等人体参数的影响。以60例中国人医学计算机断层扫描(CT)图像数据为样本,采用基于CT值分布特征的肋骨密质骨厚度测量方法,对每例CT图像的左侧12根肋骨进行了分布式测量。应用统计学方法,研究了位置和人体参数对肋骨密质骨厚度的影响。结果表明:肋骨序号、肋骨截面序号、测量点位置等位置参数和性别、身高、BMI等人体参数均对肋骨密质骨厚度具有显著影响。该研究所确立的肋骨密质骨厚度分布模型可应用于开发参数化人体有限元模型,有助于定量研究人体参数对肋骨骨折的影响。     

基于颈椎动力学响应的座椅被动安全性研究

为研究汽车后碰撞中不同的座椅靠背结构对颈部损伤的影响,基于人体解剖学和实际座椅测量数据构建了人–座椅系统有限元模型.通过后碰撞仿真模拟,得到采用不同座椅靠背时人体颈椎的应力应变响应数据,以此数据为依据进行对比分析,找出了发生事故时对汽车乘员保护性能较好的一款座椅靠背骨架结构,或可为座椅的被动安全性设计提供一种行之有效的新思路.     

碰撞中乘员有无抓握顶棚扶手下的伤害对比分析

目前在利用假人研究碰撞过程车内人员损伤程度试验中,未考虑假人抓握顶棚扶手时对人体损伤评定产生的影响,针对该问题基于LS-PREPOST和Oasys PRIMER软件建立汽车副驾驶室和具有手部抓握能力的数字假人模型,通过添加实车碰撞测试中B柱加速度曲线,模拟正面碰撞过程中加速度场,并对自由坐姿状态下和抓握顶棚扶手状态下的假人主要部位进行损伤程度对比分析。仿真结果表明,假人在抓握顶棚扶手的情况下头部合成加速度峰值和头部损伤程度指数(head injury criteria,HIC)与自由坐姿状态下假人相比降低了6.1%和30.2%,同时颈部最大剪切力、拉伸力和弯矩力分别降低了87.4%、76.9%、42.9%,胸部最大压缩量降低了16.9%。研究结果可为碰撞中被动安全领域的研究提供参考。     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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An on-line scaling method for improving scalability of a database cluster

The explosive growth of the Internet and database applications has driven database to be more scalable and available, and able to support on-line scaling without interrupting service. To support more client's queries without downtime and degrading the response time, more nodes have to be scaled up while the database is running. This paper presents the overview of scalable and available database that satisfies the above characteristics. And we propose a novel on-line scaling method. Our method improves the existing on-line scaling method for fast response time and higher throughputs. Our proposed method reduces unnecessary network use, i.e. , we decrease the number of data copy by reusing the backup data. Also, our on-line scaling operation can be processed parallel by selecting adequate nodes as new node. Our performance study shows that our method results in significant reduction in data copy time.     

An improved R-tree based on childnode''s probability

R-Tree is a good structure for spatial searching. But in this indexing structure,either the sequence of nodes in the same level or sequence of traveling these nodes when queries are made is random. Since the possibility that the object appears in different MBR which have the same parents node is different, if we make the subnode who has the most possibility be traveled first, the time cost will be decreased in most of the cases. In some case, the possibility of a point belong to a rectangle will shows direct proportion with the size of the rectangle. But this conclusion is based on an assumption that the objects are symmetrically distributing in the area and this assumption is not always coming into existence. Now we found a more direct parameter to scale the possibility and made a little change on the structure of R-tree, to increase the possibility of founding the satisfying answer in the front sub trees. We names this structure probability based arranged R-tree (PBAR-tree).     

Integrating GIS Web services based on mediating architecture

The geographic information service is enabled by the advancements in general Web service technology and the focused efforts of the OGC in defining XML-based Web GIS service. Based on these models, this paper addresses the issue of services chaining,the process of combining or pipelining results from several interoperable GIS Web Services to create a customized solution. This paper presents a mediated chaining architecture in which a specific service takes responsibility for performing the process that describes a service chain. We designed the Spatial Information Process Language (SIPL) for dynamic modeling and describing the service chain, also a prototype of the Spatial Information Process Execution Engine (SIPEE) is implemented for executing processes written in SIPL. Discussion of measures to improve the functionality and performance of such system will be included.     

Tracking data management using topology of moving object database system for moving object constrained trajectory in LBS application

Advances in wireless technologies and positioning technologies and spread of wireless devices, an interest in LBS (Location Based Service) is arising. To provide location based service, tracking data should have been stored in moving object database management system (called MODBMS) with proper policies and managed efficiently. So the methods which acquire the location information at regular time intervals then, store and manage have been studied. In this paper, we suggest tracking data management techniques using topology that is corresponding to the moving path of moving object. In our techniques, we update the MODBMS when moving object arrived at a street intersection or a curved road which is represented as the node in topology and predict the location at past and future with attribute of topology and linear function. In this technique, location data that are corresponding to the node in topology are stored, thus reduce the number of update and amount of data. Also in case predicting the location,because topology are used as well as existing location information, accuracy for prediction is increased than applying linear function or spline function.