Development of an autonomous braking system using the predicted stopping distance

An autonomous braking system is designed using the prediction of the stopping distance. The stopping distance needs to be determined by considering several factors such as the desired deceleration and the speed of the hydraulic brake actuator. In particular, the actuator speed is very critical because it affects the shape of the deceleration response and it determines the accuracy of the predicted stopping distance. The autonomous braking control algorithm is designed based on the predicted stopping distance. The proposed autonomous braking system has been validated in autonomous vehicle tests and demonstrates that the subject vehicle can avoid the collision effectively.     

Development of an auxiliary mode powertrain for hybrid electric scooter

This paper proposes a design and implementation of an auxiliary mode, hybrid electric scooter (HES) by means of more cost-effective way for improving scooter’s performance and efficiency. The HES is built in a parallel hybrid configuration with a 24V 370W auxiliary power electric motor, a 24V 20AH battery, and an electronically controlled fuel injection internal combustion engine (ICE) scooter. In contrast to hybrid electric vehicles (HEVs), the issues concerning cost, volume, and reliability are even more rigorous when developing hybrid electric scooters (HESs). Therefore, the drive topology and control strategy used in HEV cannot be applied to HES directly. In order to hasten the developing phase and achieve the parametric tune-up of the HES component, a dynamic simulation model for the HES is developed here. Because the powertrain system is complex and nonlinear in nature, the simulation model utilizes mathematical models in tandem with accumulated experimental data. The method about the mathematical model construction, analysis and simulation of the hybrid powertrain used in a scooter are fully described. The efficacy of the model was verified experimentally on a scooter chassis dynamometer and the performance of the proposed hybrid powertrain is studied using the developed model under a representative urban driving cycle. Finally, Simulation and experimental results confirm the feasibility and prosperity of the proposed hybrid HES and indicate that the designed hybrid system can improve the fuel consumption rate up to 15% compared with the original scooter.     

Experimental approach to developing human driver models considering driver’s human factors

A new approach to develop human driver models (HDMs) is proposed in accordance with the drivers’ generic human factors, i.e., gender, age, and experience, to develop more realistic vehicle simulations. The HDMs consist of three independent and stepwise models with functioning driver’s information processing stages based on the human factors: constructing drivers’ preview distance (PVD) models as a ‘cognition process’, implementing a finite preview optimal control algorithm as a ‘decision process’, and differentiating an ‘operation process’ according to neuromuscular efficiency. Eight different groups of 65 drivers with a 2 × 2 × 2 within-subject design participated in both the PVD estimates and neuromuscular efficiency tests to develop a set of statistically different HDMs. Regarding the preview distance models, an analysis of covariance (ANCOVA) procedure was adopted with two covariates (i.e., vehicle velocity and road curvature), while analyses of variance (ANOVAs) were performed on the neuromuscular efficiency parameters. The ANCOVA procedure produced eight significantly different cognition processes, whereas the ANOVAs revealed gender differences for the drivers’ neuromuscular systems. Moreover, an integrated vehicle simulation was configured with the HDMs using Carsim and Simulink software to observe the differential effects of both the cognition and operation processes on a double-lane-change (DLC) maneuver. During the simulations, gender differences in real-world DLC tests were also identified, especially between the male-oldexpert and the female-young-novice HDMs. The results presented in this study suggest that differentiating HDMs according to human factors is an essential process when utilizing vehicle simulations in the early stage of developing an intelligent vehicle system.     

Analysis of the performance of the evaporator of automotive air conditioning system

The purpose of this research was to establish a theoretical model for the evaporator of automotive air conditioning system and conducting simulations to evaluate the effect of operation parameters, environmental conditions, and design parameters on the performance of evaporator. An automotive air conditioning system primarily consists of four components: the compressor, the condenser, the refrigerant controller, and the evaporator. The refrigerant flow in the evaporator can be divided into two regions: the evaporating region and the superheat region. The refrigerant in the first region is a two-phase flow, while the refrigerant in the latter region is in the state of superheated vapor. The air flowing through the interior of the evaporator can also be divided into two zones: the unsaturated zone and the saturated zone. Water vapor is condensed in the saturated zone while in the unsaturated zone, no water condenses. Because the refrigerant flow and the airflow are perpendicular to each other, the distribution of refrigerant in the evaporating region and the superheat region does not coincide with the distribution of air in the unsaturated zone and the saturated zone. This study examines the effects of different design parameters, environmental conditions and operating parameters on the cooling capacity and superheat of an air conditioning system. Design parameters include the length of the refrigerant channel, the length of the air channel, and the thickness of the fins. Environmental conditions include the air inlet temperature and absolute humidity. Operation conditions include the refrigerant inlet enthalpy, inlet air flow rate, and refrigerant mass flow rate. Results of simulation demonstrated that fins with 50 micron meters width has the greatest cooling capacity for identical outer dimensions; thicker or thinner fins only decreased cooling capacity. Under different outer dimensions, longer refrigerant tubes and air channels created a greater cooling capacity. However, the increase in cooling capacity becomes less and less if the refrigerant flow was fixed because the heat transfer capability of the gaseous refrigerant was limited. In this study, an increase of 19% in cooling capacity can be reached as the length of refrigerant channels was increased, and the increased length of the air channels can promote the cooling capacity by 22%. Besides, it was found in this study that a decrease in the refrigerant inlet enthalpy, the inlet air flow rate, the air inlet temperature, and the inlet absolute humidity, or an increase in the refrigerant mass flow rate, would extend the superheat region and decrease the refrigerant’s superheat. It was also found that the cooling capacity of air conditioners is extremely sensitive to changes in the refrigerant mass flow rate and the inlet enthalpy, and variations more than 50% were found in the operating ranges examined in this study. However, changes in the inlet temperature, absolute humidity, and inlet air flow rate only resulted in variations between 10% and 20% in the examined ranges of conditions. Finally, a correlation among these variables and the simulated cooling capacity was obtained in this study, enabling the relevant researchers to evaluate automotive air conditioning performance under different environmental conditions and operation parameters more easily.     

Experimental study on mobility of a vehicle with CTIS in soft soil

Recently, the domestic military vehicles currently being developed are installed with a central tire inflation system (CTIS) to control the pressure of tires to increase the contact area between the tires and the ground and improve mobility on soft soils. On the other hand, it is difficult to find technical data based on experiments for designing a CTIS. In this study, to obtain the technical data to set proper pressures according to road conditions a range of mobility tests were performed on soft soil roads, such as sand and clay, according to the CTIS operating modes to obtain the technical data to set proper pressures according to the road conditions. The characteristics of the mobility and its correlation with the tire pressures in each operating mode were analyzed. The results confirmed that a wheeled vehicle with a CTIS showed better performance on soft soil than a vehicle without a CTIS.     

悬索桥基准索股架设若干影响因素分析与控制

采用数值解析法对悬索桥基准索股架设时因温度、跨径、索塔高度及索长变化引起的主跨中标点高程改变进行了研究,得到了各种影响因素在发生单位变化量时产生主揽跨中标志点标高的的影响值,提出了受各因素影响下基准索股施工架设的修正方法。实践证明:数值解析法对于现场确定和控制基准索股的高程非常有效。     

不同海拔对汽油车排放与油耗影响的研究

对一辆汽油车在海拔环境模拟舱内进行0、1 520和3 030m海拔下的排放和油耗测试,结果表明,随着海拔的升高,空气密度降低,车辆行驶阻力减小,汽油车节气门开度和点火提前角增加,排气温度降低,车辆冷起动时的排放恶化,但油耗降低;海拔3 030m处,车辆CO、THC和NOx排放增加了17.8%,8.4%和29.7%,油耗降低9.5%。     

深水定位系泊系统集成及控制系统研究

采用集中检测及控制技术将深水定位系泊系统集成为一个整体并加以控制,集成及控制系统模拟采样平台的运动坐标数据（采用仿真信号）,检测定位锚机锚索张力及长度,通过传感器检测风向、风速、海流和波浪,并实时显示和信息分析处理,建立适应复杂海洋环境下的多点系泊控制数学模型和算法演算,通过仿真实现深水定位系泊系统的自动定位控制功能。     

基于Petri网的登陆作战中协同通信的性能评价

论文以登陆作战中协同通信为研究背景,通过对Petri网的理论介绍,论证了运用SPN分析登陆作战中协同通信系统进行性能评价的可能性,并建立了基于Petri网的登陆作战中协同通信的数学模型,最后给出了登陆作战中集团军内部组织协同通信网,协同动作的延时时间。论文对登陆作战中协同通信研究有一定借鉴意义。     

The method of imbedded Lagrangian element to estimate wave power absorption by some submerged devices

A simple approach is described to estimate the wave power absorption potential of submerged devices known to cause wave focusing and flow enhancement. In particular, the presence of a flow-through power take-off （PTO） system, such as low-head turbines, can be accounted for. The wave radiation characteristics of an appropriately selected Lagrangian element （LE） in the fluid domain are first determined. In the limit of a vanishing mass, the LE reduces to a patch of distributed normal dipoles. The hydrodynamic coefficients of this virtual object are then input in a standard equation of motion where the effect of the PTO can be represented, for example, as a dashpot damping term. The process is illustrated for a class of devices recently proposed by Carter and Ertekin （2011）, although in a simplified form. Favorable wave power absorption is shown for large ratios of the LE wave radiation coefficient over the LE added mass coefficient. Under optimal conditions, the relative flow reduction from the PTO theoretically lies between 0.50 and 1 2 ≈ 0.71, with lower values corresponding to better configurations. Wave power capture widths, the sensitivity of results to PTO damping and sample spectral calculations at a typical site in Hawaiian waters are proposed to further illustrate the versatility of the method.