Different human-simulated characteristics of the driver models in the forward simulation of hybrid electric vehicles

Based on the control theories of PID, fuzzy logic and expert PID, the driver models are built and applied in the forward simulation for hybrid electric vehicles （HEV）. The impact to the vehicle speed tracking and the fuel economy is compared among the different driver models. The different human-simulated characteristics of the driver models are emphatically analyzed. The analysis results indicate that the driver models based on PID, simple fuzzy logic and expert PID are corresponding to the handling characteristics of different drives. The driver models of different human-simulated characteristics bring the handling divergence of drivers with different driving level and habit to the HEV forward simulation, and that is significant to the all-around verification and validation of the control strategy for HEV. System simulation results of different driver models validate the impact of driver models to the dynamic and fuel economy performance of HEV.

Numerical simulation and response analysis of microspherical focused logging in inclined micro-fractured formation

Tight and unconventional reservoirs have become the focus with the progress of petroleum exploration and development.Micro-fractures in these reservoirs can effectively improve reservoir permeability,and well-developed micro-fractures can serve to directly improve productivity.Compared with the centered electrical well logging method,the Micro Spherical Focused Logging(MSFL)is more suitable for microfracture identification due to its high resolution and near borehole wall measuring method.In this study,an anisotropic model is used to depict micro-fractured formation.First,a forward model with microfractured formation,borehole,logging instrument and surrounding rock is established.Subsequently,MSFL responses under different micro-fracture porosity,resistivity,dip angle and borehole radius,are calculated based on the finite element method(FEM).Finally,the MSFL responses under different microfracture parameters are analyzed with the response laws clarified.

Dynamic flight stability of a bumblebee in forward flight

The longitudinal dynamic flight stability of a bumblebee in forward flight is studied. The method of computational fluid dynamics is used to compute the aerodynamic derivatives and the techniques of eigenvalue and eigenvector analysis are employed for solving the equations of motion. The primary findings are as the following. The forward flight of the bumblebee is not dynamically stable due to the existence of one （or two） unstable or approximately neutrally stable natural modes of motion. At hovering to medium flight speed [flight speed Ue = （0-3.5）m s^-1; advance ratio J = 0-0.44], the flight is weakly unstable or approximately neutrally stable; at high speed （Ue = 4.5 m s^-1; J = 0.57）, the flight becomes strongly unstable （initial disturbance double its value in only 3.5 wingbeats）.

Simulation research and application on response characteristics of detecting water-filled goaf by transient electromagnetic method

Water inrush disasters poses a great threat to the safe exploitation of coal resources.To solve this problem,the transient electromagnetic method(TEM)was proposed to accurately detect the water accumulation in the goaf.The electromagnetic response characteristics of diferent water-flled goaves were studied by electromagnetic feld theory,numerical simulation and feld verifcation.Through the models of 100%water accumulation,50%water accumulation,0%water accumulation,100%water accumulation with collapsed rock,50%water accumulation with collapsed rock and 0%water accumulation with collapsed rock goaf,the characteristics of induced voltage attenuation curves were studied.Meanwhile,the relationship between the attenuation voltage value and area of the transmitting coil,the depth of the goaf,the background resistivity,and the delay time were also simulated.The results illustrate that the attenuation curve of induced voltage presented a regular exponential decay form in the 0%water accumulation model but existed abnormal exaltation for voltage in water-flled model.Through the linear ftting curve,it can be seen that the abnormal intensity of the induced voltage becomes stronger as the distance between the measuring point and the center of the target decrement.Moreover,the abnormal amplitude of the induced voltage increases with the rise of the water accumulation and collapsed rock will weakly reduce the low-resistivity anomalous efect on the water-accumulated goaf.In addition,the response value of the attenuation voltage increased as the area of the transmitting coil increases,but decreased with increasing delay time and increasing background resistivity and depth of the target body.The feld detection results of the Majiliang coal mine also confrmed the theoretical analysis and the numerical simulation.

Evaluation of Transmission Losses of Various Battery Electric Vehicles

Transmission losses in battery electric vehicles have compared to internal combustion engine powertrains a larger share in the total energy consumption and play therefore a major role.Furthermore,the power flows not only during propulsion through the transmissions,but also during recuperation,whereby efficiency improvements have a double effect.The investigation of transmission losses of electric vehicles thus plays a major role.In this paper,three simulation models of the Institute of Automotive Engineering(the lossmap-based simulation model,the modular simulation model,and the 3D simulation model)are presented.The lossmap-based simulation model calculates transmission losses for electric and hybrid transmissions,where three spur gear transmission concepts for battery electric vehicles are investigated.The transmission concepts include a single-speed transmission as a reference and two two-speed transmissions.Then,the transmission lossmaps are integrated into the modular simulation model(backward simulation)and in the 3D simulation model(forward simulation),which improves the simulation results.The modular simulation model calculates the optimal operation of the transmission concepts and the 3D simulation model represents the more realistic behavior of the transmission concepts.The different transmission concepts are investigated in Worldwide Harmonized Light Vehicle Test Cycle and evaluated in terms of transmission losses as well as the total energy demand.The map-based simulation model allows the transmission losses to be broken down into the individual component losses,thus allowing transmission concepts to be examined and evaluated in terms of their efficiency in the early development stage to develop optimum powertrains for electric axle drives.By considering transmission losses in detail with a high degree of accuracy,less efficient concepts can be eliminated at an early development stage.As a result,only relevant concepts are built as prototypes,which reduces development costs.

Real-Time Trajectory Planning for On-road Autonomous Tractor-Trailer Vehicles

Tractor-trailer vehicles,which are composed of a car-like tractor towing a passive trailer,have been widely deployed in the transportation industry,and trajectory planning is a critical step in enabling such a system to drive autonomously.Owing to the properties of being highly nonlinear and nonholonomic with complex dynamics,the tractor-trailer system poses great challenges to the development of motion-planning algorithms.In this study,an indirect trajectory planning framework for a tractor-trailer vehicle under on-road driving is presented to deal with the problem that the traditional planning framework cannot consider the feasibility and quality simultaneously in real-time trajectory generation of the tractor-trailer vehicle.The indirect planning framework can easily handle complicated tractor-trailer dynamics and generate high-quality,obstacle-free trajectory using quintic polynomial spline,speed profile optimization,forward simulation,and properly designed cost functions.Simulations under different driving scenarios and trajectories with different driving requirements are conducted to validate the performance of the proposed framework.