General stochastic user equilibrium traffic assignment problem with link capacity constraints

This paper addresses a general stochastic user equilibrium (SUE) traffic assignment problem with link capacity constraints. It first proposes a novel linearly constrained minimization model in terms of path flows and then shows that any of its local minimums satisfies the generalized SUE conditions. As the objective function of the proposed model involves path‐specific delay functions without explicit mathematical expressions, its Lagrangian dual formulation is analyzed. On the basis of the Lagrangian dual model, a convergent Lagrangian dual method with a predetermined step size sequence is developed. This solution method merely invokes a subroutine at each iteration to perform a conventional SUE traffic assignment excluding link capacity constraints. Finally, two numerical examples are used to illustrate the proposed model and solution method.     

Deviated state detection method in driving around curves based on naturalistic driving behavior database for driver assistance systems

The objective of this study is to propose the indices which detect the deviated state of drivers while driving by considering drivers’ judgment process and using road environment and naturalistic driving behavior database. To realize this objective, drivers’ speed choice behavior around curve situations was focused and the speed choice process was formulated. Moreover, a deviated state detection method considering the formulated speed choice process around curve situations was proposed and the validity of the method was examined.     

Numerical determination of flushing time for stratified water bodies

It is often advantageous to model a semi-enclosed estuarine or coastal embayment (e.g. fish farms or tidal inlets, or typhoon shelters) as a separate system within a larger water body connected to the outer sea. The water quality of the system depends crucially on its flushing time—the average time of a particle in the system. The flushing time is governed by the barotropic and baroclinic tidal exchanges between the system and the outer sea. We describe herein a general method to determine systematically the flushing time of a stratified water body via a numerical tracer experiment. Numerical solution of the 3D flow and mass transport equations for many practical problems show that the tracer mass removal process depends on the physical topography and bathymetry, tidal range and the degree of stratification in the outer sea. Field application suggests that the tracer mass variation can be well approximated by a double-exponential decay curve that can be described by three flushing coefficients. Using a simple analytical two-segment model, the flushing coefficients can be given a clear physical interpretation, and the flushing time can be easily determined in terms of the coefficients. The method is illustrated by application to a number of tidal inlets in Hong Kong, in both the dry and wet season. The connection between the numerically determined flushing time and the traditional bulk flushing time obtained from salt-balance methods is established.     

IGCT无吸收和串联工作电路仿真的新型有效的物理模型

文章讨论了用Saber MAST软件完成电路仿真,并精确计算集成门极换流晶闸管(IGCT)静态和动态性能的新物理模型.通过仿真结果与硬开关无吸收工作中4.5 kV/3 kA IGCT的试验结果的比较验证了该模型.此外,文章还分析了2个串联IGCT开关的仿真结果,特别是在忽略无吸收电路时器件特性和门极驱动存在的必然差别引起的关于开关之间阻断电压非均衡分布的问题.还给出了计算吸收容量的一种想法.     

High speed driving stability of passenger car under crosswind effects

The driving stability of a passenger car at high-speed and under crosswind conditions is affected by aerodynamic characteristics as well as their dynamic characteristics, suspension, and weight distribution. In this study, the total measuring system was thought up to understand the transient vehicle dynamics and aerodynamics with driver’s control inputs all together. The test results were taken from a full-scale wind tunnel test, a crosswind generator test and an on-road test. We investigated major aerodynamic parameters that affect the driving stability of passenger cars under crosswind effects such as overtaking, passing each other, natural crosswind, etc. The reaction rate of high-speed stability will be improved when we minimize the total lift, side force and especially the yawing moment.     

Characteristics of flame kernal radius in a spark ignition engine according to the electric spark ignition energy

To study flame propagation in a spark ignition engine, it must concentrate on the initial combustion stage, i.e., the formation and development of flame. Therefore, we must study the theoretical calculation of minimum flame kernel radius which affects the formation and development of flame kernel. To calculate the minimum flame kernel radius, we must know the thermal conductivity, flame temperature, laminar burning velocity, etc. To evaluate the accuracy of the minimum flame kernel radius based on the theory, authors compared with those from calculation and those from tests. According to the increase of number of sparks and spark intervals, the flame kernel radii become to increase and the expected lean limits are extended. It is considered that is due to the stability of combustion as increase of flame kernel size according as high ignition energy supplies in initial period and discharge energy period lengthens.     

Parallel model based fault detection algorithm for electronic parking brake system

This paper describes a parallel model-based fault detection algorithm for an electronic parking brake (EPB) system, which consists of an electronic control unit with built-in current sensor and braking force sensor. For the EPB system to supply sufficient parking force to a vehicle, the parking force sensor is of utmost importance. If a fault occurs in this sensor, sufficient parking force may not be supplied, thereby seriously threatening the safety of the vehicle. Thus, a fault detection method is required for the parking force sensor of the EPB system to improve the safety of vehicles. For this purpose, a highly reliable fault detection method is needed to detect abnormal fault signals, which cannot be detected by the existing on-line sensor monitoring fault detection methods. This paper proposes a novel parallel model-based fault detection algorithm for the EPB system, which compares the physical sensor data with the mathematical model, the fuzzy model, and the neural network model at the same time. In order to reduce false alarms, the magnitude of thresholds and the operation counts are changed adaptively. When the proposed parallel model-based fault detection algorithm detects severe failures of the force sensor, it warns the driver in advance to prevent accidents due to the failures. The proposed algorithm is verified by hardware-in-theloop simulations in various situations.     

Co-operative control for regenerative braking and friction braking to increase energy recovery without wheel lock

This paper presents a regenerative braking co-operative control algorithm to increase energy recovery without wheel lock. Considering the magnitude of the braking force available between the tire and road surface, the control algorithm was designed for the regenerative braking force at the front wheel and friction braking force at the rear wheel to be increased following the friction coefficient line. The performance of the proposed regenerative braking co-operative control algorithm was evaluated by the hardware in the loop simulation (HILS) with an electronic wedge brake on its front wheels and an electronic mechanical brake on its rear wheels. The HILS results showed that a proper braking force on the front and rear wheels on a low μ road prevented the lock of the front wheels that was connected to the motor, and maintained the regenerative braking and increased energy recovery.     

Automatic parking of vehicles: A review of literatures

Collision accidents often occur during parking or reversing cars. In allusion to this point, this paper conducts a review of literatures on automatic parking. To begin with, a brief introduction of automatic parking including its background and significance is given. Then its commercial application, research status and latest progress are summarized which include visual perception, ultrasonic sensors and radar technology, path planning, control algorithms based on fuzzy theory, neural network, image processing and recognition technology, and digital signal processing technology, etc. On further analysis, some reasonable conclusions are drawn and the future work is suggested.     

Method for precise controlling of the at shift control system

The shift comfort and efficiency of Automatic Transmission in vehicle are highly influenced by the pressure of the clutch shift control system, especially by the electro-hydraulic clutch subsystem. In this paper, the new design principles of electro-hydraulic clutch systems developed and modeled in detail, the clutch-to-clutch control system is analyzed in three time intervals: oil filled phase, changing phase of clutch torque and synchronous phase of clutch speed. The demand pressures for the engaged clutches calculated in each phase and is precisely built up by using fuzzy slide mode control, the time of hydraulic pressure building-up is very sensitive to the dither current in simulation. All control parameters are optimized by Cosimulation between software Simulink and SimulationX. Finally, the optimal algorithm of the clutch shift control is written into the transmission control unit of a testing vehicle. The testing results show that the suggested control strategy is effective.