Zur Steuerbarkeit eines gebremsten Sattelschleppzuges

(Title: On Controllability of a Tractor-Semitrailer Truck During Braking)

The concept of controllability coming from linear system theory is applied to the motion of a tractor-semitrailer vehicle during straight-line braking. Some states of braking with locked up wheels at different axles are considered. The question whether the system is always controllable must be answered in the negative for locked up wheels at the tractors front axle. In other cases controllability in its mathematical meaning which, however, does not always appear to be fully adequate for practical problems, is possible.     

猴细小病毒Vp2的克隆、表达和鉴定

目的　克隆、表达和鉴定猴细小病毒 (simianparvovirus,SPV)Vp2蛋白。方法　用设计的SPVVp2区的特异性引物 ,PCR法扩增SPVVp2基因DNA片断 ;将获得的基因片断插入 pThioHisA载体中 ,转化大肠杆菌DH5α后挑选阳性克隆 ,利用限制性内切酶酶切和核酸序列分析技术鉴定重组质粒 ;以LB培养液培养转化有插入SPVVp2基因的pThioHisA载体的大肠杆菌 ,以终浓度 1mmol·L -1的IPTG诱导蛋白的表达 ;用SDA PAGE和Westernblot分析和鉴定表达的蛋白。结果　经限制性内切酶酶切和核酸序列分析 ,获得了插入pThioHisA载体框架的SPVVp2基因的表达质粒 ;阳性转化大肠杆菌在IPTG诱导下获得了SPVVp2蛋白的表达 ;SDA PAGE和用抗 Thio及抗 SPVVp2的特异性抗体的Westernblot分析证实了表达蛋白的特异性。结论　获得了SPVVp2基因的表达质粒并在大肠杆菌中得了高效表达 ,为进一步建立SPV感染的检测方法和研究SPV的血清流行病学等奠定了基础。     

基于SP调查的天津市居民出行行为时间价值

为揭示天津市居民出行行为时间价值的一般规律,采用SP调查中的卡片式面谈调查法,运用市场细分法确定调查规模及抽样率,采用计算包容性检查矩阵等数据处理手段,估算天津市居民出行行为时间价值。比较了出行行为时间价值与单位工作时间价值之间的关系,并分析了不同出行方式、出行目的、出行时段的时间价值,研究了出行收入与时间价值的变化规律。得出现阶段天津市居民出行行为时间价值的分布,表明大部分出行者不愿为出行支付较高费用,但随着收入增加,出行行为时间价值将会快速增长,使个体机动化出行方式的需求增大,城市出行方式结构可能出现拐点。     

临床致病性不动杆菌的分子生物学鉴定

目的对临床致病性不动杆菌进行种属鉴定,并比较3种方法(44℃生长试验、特异性引物PCR扩增和16SrRNA测序)对鲍曼不动杆菌鉴定的特异性、准确性及应用价值。方法收集临床致病不动杆菌56株,首先接种在胰蛋白胨大豆肉汤中44℃进行培养,观察是否可以生长;其次,提取56株不动杆菌基因组DNA,用两组不同的特异性引物进行PCR扩增鉴定;最后,用通用引物对56株不动杆菌的16SrRNA进行测序鉴定。结果 56株不动杆菌中有17株可在44℃生长。经特异性引物PCR扩增鉴定,发现8株鲍曼不动杆菌和3株13TU型不动杆菌均可在44℃中较早较快生长。金标准16SrRNA测序确定56株不动杆菌中含有9个种,其中鲍曼不动杆菌和13TU型不动杆菌的鉴定结果与特异性引物PCR扩增法相同。结论应用分子生物学方法鉴定鲍曼不动杆菌具有准确、高效且可重复性高的优点,尤其是特异性PCR扩增法,可作为较难诊断的鲍曼不动杆菌的首选鉴定方法。     

辽宁区域超声回弹综合法测强曲线的建立

通过大量的室内外试验检测工作及相关理论分析,建立了辽宁区域超声回弹综合法测强曲线,提高了检测精度。     

Development of an electric active rollcontrol (ARC) algorithm for a SUV

Cornering maneuvers with reduced body roll and without loss in comfort are leading requirements for car manufacturers. An electric active roll control (ARC) system controls body roll angle with motor-driven actuators installed in the centers of the front and rear stabilizer bars. A vehicle analysis model developed using a CarSim S/W was validated using vehicle test data. Two ARC algorithms for a sports utility vehicle (SUV) were designed using a sliding-mode control algorithm based on a nonlinear roll model and an estimated lateral acceleration based on a linearized roll model. Co-simulation with the Matlab simulink controller model and the CarSim vehicle model were conducted to evaluate the performance of two ARC control algorithms. To validate the ARC performance in a real vehicle, vehicle tests were conducted at KATECH proving ground using a small SUV equipped with two ARC actuators, upper and lower controllers and a few subsystems. From the simulation and vehicle validation test results, the proposed ARC control algorithm for the developed ARC actuator prototypes improves the vehicle’s dynamic performance.     

Effect of the fuel injection strategy on first-cycle firing and combustion characteristics during cold start in a TSDI gasoline engine

The first firing cycle is very important during cold-start for all types of spark ignition engines. In addition, the combustion characteristics of the first firing cycle affect combustion and emissions in the following cycles. However, the first-cycle fuel-air mixing, combustion and emissions generation within the cylinder of a two-stage direct-injection (TSDI) engine during cold start is not completely understood. Based on the total stoichiometric air-fuel ratio and local richer mixture startup strategy, the first-cycle firing and combustion characteristic at cold start were investigated in a two-stage direct injection (TSDI) gasoline engine. In addition, the effects of the first injection timing, second injection timing, 1st and 2nd fuel injection proportion and total excess air ratio on the in-cylinder pressure, heat release rate and accumulated heat release were analyzed on the basis of a cycle-by-cycle analysis. It is shown that a larger 2nd fuel injection amount and later 2nd injection timing are more beneficial to the firing of the first cycle in the case of a total excess air ratio of 1.0. The optimum 1st and 2nd injection timing fuel injection proportions are 120°CA ATDC during the intake stroke, 60°CA BTDC during the compression stroke and 1:1. In addition, the firing boundary is a 2nd injection timing later than 90°CA BTDC during the compression stroke in the case of the 1st injection timing from 60°CA to 180°CA ATDC during an intake stroke and involves a 1st and 2nd fuel injection proportion of 1:1 and an excess air ratio of 1.0. The study provides a detailed understanding of cold-start combustion characteristics and a guide for optimizing the reliable first-cycle firing at cold start.     

New metal fitting geometry and optimization of the swaging parameters for an automobile power steering hose

To solve the power steering (PS) hose oil leakage problem in automobile applications, a new geometry design of the metal fitting is required, and the swaging conditions applied to the PS hose should be optimized. In this study, a new metal fitting geometry for the PS hose was proposed. A CAE simulation for both the proposed and the conventional metal fittings was conducted, and both the stress and the strain in the PS hose were compared. An experimental verification was also performed with these two different metal fittings. Additionally, the swaging conditions were optimized by the durability cycle time, which was measured in an impulse test of the swaged PS hose. For a more economical production, practical working conditions were also recommended and experimentally verified.     

A simplified model for evaluating tire wear during conceptual design

In the field of vehicle dynamics, commercial software can aid the designer during the conceptual and detailed design phases. Simulations using these tools can quickly provide specific design metrics, such as yaw and lateral velocity, for standard maneuvers. However, it remains challenging to correlate these metrics with empirical quantities that depend on many external parameters and design specifications. This scenario is the case with tire wear, which depends on the frictional work developed by the tire-road contact. In this study, an approach is proposed to estimate the tire-road friction during steady-state longitudinal and cornering maneuvers. Using this approach, a qualitative formula for tire wear evaluation is developed, and conceptual design analyses of cornering maneuvers are performed using simplified vehicle models. The influence of some design parameters such as cornering stiffness, the distance between the axles, and the steer angle ratio between the steering axles for vehicles with two steering axles is evaluated. The proposed methodology allows the designer to predict tire wear using simplified vehicle models during the conceptual design phase.     

Road identification in monocular color images using random forest and color correlogram

This paper presents a system to identify road and non-road regions from monocular color images of paved and unpaved roads. Despite being a single object, the road in these images is subject to large changes in appearance due to environmental effects and track materials. This condition has challenged the practical application of road identification. The proposed system combines random forest with color correlogram to overcome such conditions and offers a classifier for road and non-road regions in traffic images. As a color feature, the color correlogram depicts the spatial correlation of color changes in an image. Using random forest, road identification is formulated as a learning paradigm. The combined effects of color correlograms and random forest create a robust system capable of identifying roads even in variable situations in real time. This combination is more effective than other combinations, such as a color histogram plus random forest, a color correlogram plus neural network, or a color histogram plus neural network.