道路交叉口指路标志定量分析指标及方法研究

针对目前我国对指路标志信息内容组成及协调设置尚无明确规定的现状,对已有的指路标志分析方法及指标作汇总和扩展补充,提出了道路交叉口指路标志定量分析的2个方法:路段分析法与区域分析法,并给出了指路标志设置率与指示范围、道路间相互指示关系等一系列用于上述分析方法的定量分析指标。接着以广州市海珠中心区为例,基于对该区域内主干道指路标志现状的数据采集与调查研究,选取了典型的主干道及交通区域作实例分析。     

神秘来客BMW CONCEPT 5 SERIES GRAN TURISMO

宝马汽车公司在2009年的日内瓦车展上为广大消费者带来了一款基于5系的GT（赛车）概念车．该车融合了宝马运动型轿车、SAV（运动型多功能车）和经典GT车型的设计元素,为宝马开辟了一个全新的细分市场。     

钛合金中杂质元素的ICP—AES测定法

研究与运用电感耦合等离子体发射光谱仪（ＩＣＰ－ＡＥＳ）测定钛合金中Ａｌ、Ｃｕ、Ｆｅ、Ｓｎ、Ｖ杂质元素。其方法是用盐酸处理试样,选择适当的酸度和分析线,采用标准加入法排除谱线干扰及基体干扰。其方法简便、速度快,准确性、精确性好。     

个性化教学设计可视化建模的研究与实现

对网络环境下基于建构主义个性化教学设计进行了分析,利用教学元素以可视化建模方式实现个性化教学设计。     

Numerical Simulation of Projection Welding Processes for Door Hinge of Automobile Based on Coupled Fields Analysis

Projection welding is a variation of electric resistance welding with the dynamic changes of the flow paths for heat and electrical properties with changing temperature caused by the large plastic deformation collapse of projection. As the joint type between the auto door hinge and the inner plate, projection welding may bring welding distortions and would affect the assembly quality of auto body. A comprehensive electric-thermal-mechanical numerical simulation was performed to quantitatively simulate the processes of projection welding by using a coupled finite element method. The mechanism of projection collapse and the formation process of nugget were discussed and good conclusions have been achieved comparing with the test results.     

古典与现代科技的结晶——2007年BMW R1200R新路星

一提起BMW,人们就会与制作精良、安全稳定、速度迅猛联系起来.2007年新款R1200R正是在秉承BMW优良传统的基础上再做突破,将现代高科技元素融入其中,将速度、安全、灵活性的设计理念贯彻始终的典范.     

拔山尽力永不言败——凯旋的Speed Triple 1050NK车

近年来,街车跑车化似乎已成为一种国际流行趋势,因为它加入了诸多时尚运动元素,特别适合年轻人的口味.英国凯旋(TRIUMPH)这家百年老店也对自己生产的摩托车作了多次重大改革,并推出了一系列性能独特、品质卓越的新款.本次的主角便是Speed Triple 1050,一辆性能强悍的街跑车.     

BMW新款R1200R的七项新技术(上)

BMW 2007年雷霆上市的新款R1200R,集合了当代7项最新高科技元素,以创新和实力"亮剑",非常值得我们学习借鉴.     

火花塞间隙对发动机点火波形影响的研究

发动机点火系统工作性能的好坏,直接影响到汽车的动力性、经济性、安全性、噪声和废气排放。本文从点火波形分析入手,研究发动机火花塞间隙变化对点火波形的影响,通过定性定量分析,找出点火次级波形各参数的变化规律,为点火系统故障诊断提供理论依据。     

Application of dual reciprocity boundary element method to predict acoustic attenuation characteristics of marine engine exhaust silencers

In marine engine exhaust silencing systems, the presence of exhaust gas flow influences the sound propagation inside the systems and the acoustic attenuation performance of silencers. In order to investigate the effects of three-dimensional gas flow and acoustic damping on the acoustic attenuation characteristics of marine engine exhaust silencers, a dual reciprocity boundary element method （DRBEM） was developed. The acoustic governing equation in three-dimensional potential flow was derived first, and then the DRBEM numerical procedure is given. Compared to the conventional boundary element method （CBEM）, the DRBEM considers the second order terms of flow Mach number in the acoustic governing equation, so it is suitable for the cases with higher Mach number subsonic flow. For complex exhaust silencers, it is difficult to apply the single-domain boundary element method, so a substructure approach based on the dual reciprocity boundary element method is presented. The experiments for measuring transmission loss of silencers are conducted, and the experimental setup and measurements are explained. The transmission loss of a single expansion chamber silencer with extended inlet and outlet were predicted by DRBEM and compared with the measurements. The good agreements between predictions and measurements are observed, which demonstrated that the derived acoustic governing equation and the DRBEM numerical procedure in the present study are correct.