Conceptual Modular Design of Auto Body Frame Based on Hybrid Optimization Method

This article presents a systematic research methodology of modular design for conceptual auto body frame by hybrid optimization method.A modified graph-based decomposition optimization algorithm is utilized to generate an optimal BIW assembly topo model composed of“potential modules”.The consistency constraint function in collaborative optimization is extended to maximize the commonality of modules and minimize the performance loss of all car types in the same product family simultaneously.A novel screening method is employed to select both“basic structures”and“reinforcement”modules based on the dimension optimization of the manufacturing elements and the optimal assembly mode;this allows for a more exhaustive modular platform design in contrast with existing methods.The proposed methodology is applied to a case study for the modular design of three conceptual auto body types in the same platform to validate its feasibility and effectiveness.

Objective Quantification of Small Motor Sound Quality Based on Psychoacoustic Metrics

With the widespread application of electrification and intelligence of automobiles,the number of electric devices with small DC motors in automobiles has gradually increased,and the in-terior of electric vehicles is quieter.The sound quality(SQ)of small motor directly affects the pas-senger experience.Therefore,the research on the SQ of small motor is of great significance.In this paper,the objective quantification of small motor sound quality was investigated based on tradi-tional psychoacoustic metrics.The time-frequency characteristics of sound signal was analyzed to quantify the subjective perception caused by the sound of small motor.And a new psychoacoustic metrics of objective evaluation which were suitable for small motor SQ evaluation were proposed,namely specific loudness energy(SLE),specific prominence ratio index(SPRI),relative pitch exceedance(RPE)and tremolo index(TI).Then,two objective evaluation models of small motor SQ were established to characterize the multi-dimensional subjective perception attributes by using multiple linear regression(MLR)and support vector regression(SVR)respectively,which can be used for the prediction and evaluation of the small motor SQ.The results show that the prediction accuracy of the model established by SVR method was higher than that of MLR,and SVR has stronger robustness.The objective evaluation model of small motors SQ established in this study is of great importance for improving the sound quality of small motors.

Mathematical Statistics Method of Residual Static Torque Controlling

This paper analyzes the problems existing in the detection and determination on the traditional residual torque. It is pointed out that the detection value is mistakenly used as the truth value and the lower limit of design torque is mistakenly used as the residual torque criterion. The calculation formula of the determination （limit） value of the test value of RM and DFM is proposed. By defining related parameters,the torque limitvalue corresponding to the tightening level, the ratio of the measured value to the truth value, μ and σ related tothe ratio of A and C, and the confidence coefficient related to the confidence probability, a mathematical statistical method of residual static torque controlling is established, which improves the control precision on the residual torque.

A new insight into the stability of nanofiber electrodes used in proton exchange membrane fuel cells

The nanofiber electrodes have been considered as promising candidates for commercial proton exchange membrane fuel cells due to their high catalyst utilization and enhanced mass transport efficiency.However,for the first time our research determined that the nanofiber electrodes were restricted by the poor chemical stability of the polymer carriers.To gain further insight into the durability of nanofiber electrodes,both cyclic voltammetry aging tests and Fenton’s tests were conducted.Similar to previous reports,our research demonstrated that nanofiber electrodes showed remarkable stability in the cyclic voltammetry aging process.However,Fenton’s tests indicated that nanofibers in the electrodes would decompose easily while being attacked by reactive oxygen species such as HO·or HOO·,which greatly limits their practicability and reliability.The different performances under the two tests also demonstrated that the cyclic voltammetry aging protocols,which have been applied extensively,cannot well mirror the real operating conditions of fuel cells.

Investigation into Improvement for Anti-Rollover Propensity of SUV

Currently, many research from domestic and foreign on improving anti-rollover performance of vehicle mainly focus on the electronic control of auxiliary equip- ment, do not make full use of suspension layout to optimize anti-rollover performance of vehicle. This investigation into anti-rollover propensity improvement concentrates on the vehicle parameters greatly influencing on anti-rollover propensity of vehicle. A simulation based on fishhook procedure is used to perform design trials and evaluations aimed at ensuring an optimal balance between vehicle＇s design parameters and various engineering capacities, the anti-rollover propensity is optimized at the detailed design stage of a new SUV model. Firstly a four-DOF theoretical kinematic model is established, then a complete multi-body dynamics model built in ADAMS/car based on the whole vehicle parameters is correlated to the objective handing and stability test results of a mule car. Secondly, in fish- hook test simulations, the Design of Experiments method is used to quantify the effect of the vehicle parameters on the anti-rollover performance. By means of the simulation, the roll center height of front suspension should be more than 30 mm, that of rear suspension less than 150 mm, and the HCG less than 620 mm for the SUV. The ratio of front to rear suspension roll stiffness should be ranged from 1.4 to1.6 for the SUV. As a result, at the detailed design stage of product, the anti-rollover performance of vehicle can be improved by optimizing chassis and integrated vehicle parameters.

Optimum Driving System Design for Dual-Motor Pure Electric Vehicles

A pure electric vehicle driven by dual motors is taken as the research object and the driving scheme of the driving motor is improved to increase the transmission efficiency of existing electric vehicles.Based on the architecture of the transmission system,we propose vehicle performance parameters and performance indexes of a pure electric vehicle,a time-sharing driving strategy of dual motors.First,the parameters of the battery,motor,and transmission system are matched.Then,the electric vehicle transmission model is built in Amesim and the control strategy is designed in Simulink.With the optimization goal of improving the vehicle’s dynamic performance and driving range,the optimal parameters are determined through analysis.Finally,the characteristics of the motor are tested on the bench.The results show that the energy-saving potential of the timesharing driven double motor is higher,and the driving mileage of the double motor drive is increased by 4%.

Multiple Scattering Between Adjacent Sound Sources in Head-Related Transfer Function Measurement System

To accelerate head-related transfer functions(HRTFs)measurement,two or more independent sound sources are usually employed in the measurement system.However,the multiple scattering between adjacent sound sources may influence the accuracy of measurement.On the other hand,the directivity of sound source could induce measurement error.Therefore,a model consisting of two spherical sound sources with approximate omni-directivity and a rigid-spherical head is proposed to evaluate the errors in HRTF measurement caused by multiple scattering between sources.An example of analysis using multipole re-expansion indicates that the error of ipsilateral HRTFs are within the bound of±1.0 dB below a frequency of 20 kHz,provided that the sound source radius does not exceed 0.025 m,the source distance relative to head center is not less than 0.5 m,and the angular interval between two adjacent sources is not less than 20 degrees.Similar conclusions under different conditions can also be analyzed and discussed by using this calculation method.Furthermore,the results are verified by measurements of HRTFs for a rigid sphere and a KEMAR artificial head.

Evaluation of regenerative braking based on single-pedal control for electric vehicles

More than 25%of vehicle kinetic energy can be recycled under urban driving cycles.A single-pedal control strategy for regenerative braking is proposed to further enhance energy efficiency.Acceleration and deceleration are controlled by a single pedal,which alleviates driving intensity and prompts energy recovery.Regenerative braking is theoretically analyzed based on the construction of the single-pedal system,vehicle braking dynamics,and energy conservation law.The single-pedal control strategy is developed by considering daily driving conditions,and a single-pedal simulation model is established.Typical driving cycles are simulated to verify the effectiveness of the single-pedal control strategy.A dynamometer test is conducted to confirm the validity of the simulation model.Results show that using the single-pedal control strategy for electric vehicles can effectively improve the energy recovery rate and extend the driving range under the premise of ensuring safety while braking.The study lays a technical foundation for the optimization of regenerative braking systems and development of single-pedal control systems,which are conducive to the promotion and popularization of electric vehicles.

Outsourcing or Not? The OEMrs Better Collecting Mode under Cap-and-Trade Regulation

Many original equipment manufacturers(OEMs)carry out collecting operations by themselves or a third party.Most of the existing research papers in the literature consider the collecting mode selection problem from an economic perspective.However,in practice,the firm's collecting decisions can be affected by the carbon policies at present.This paper aims to bridge the gap in research on remanufacturing supply chain by taking the effects of cap-and-trade regulation into consideration.Stackelberg models are established to study the quantity and price decisions under different collecting modes.We find that the OEM reaps more profits in the OEM collecting mode than the third-party collecting mode when collection cost is large.Otherwise,the third party has lower collection cost,and the third-party collecting mode may make the OEM more profitable.From an environmental perspective,with high collection cost,the third party collecting mode can reduce the carbon emissions unless the cost of new products and the emissions intensity are small.In addition,when the collection cost is low but the quantity of remanufacturing products is restricted by that of new products,the third party collecting mode may increase the carbon emissions.In addition,the implementation of cap-and-trade regulation can always reduce carbon emissions,and it may increase the OEM's profits if consumers preference for remanufactured products is small.

Analysis and evaluation of electromagnetic vibration and noise in permanent magnet synchronous motor with rotor step skewing

In this paper, a multi-physics simulation model capable of electromagnetic noise prediction is established, and the effectiveness of the established simulation model in predicting and evaluating electromagnetic noise is verified. Based on the verified motor model, a rotor step skewing model which can affect electromagnetic noise is proposed, and the influence of the skewing angle on electromagnetic noise is investigated in detail. By studying the spectral characteristics of the low-order radial magnetic force which has a great influence on electromagnetic noise, the distribution of electromagnetic noise characteristics of the permanent magnet synchronous motor(PMSM) with or without the rotor step skewing is compared and analyzed. Therefore, it lays a technological foundation for predicting and suppressing the electromagnetic vibration noise of electric vehicle(EV) driving motor in the electromagnetic design.

Al–9.00 %Si–0.25 %Mg alloys modified by ytterbium

The effects of ytterbium（Yb） on microstructure and solidification behavior of Al-9.00%Si-0.25%Mg alloys were investigated.By optical microscope（OM） and scanning electron microscopy（SEM）,it is found that the morphology of eutectic silicon changes from coarse plates to fine fibers by the addition of 0.7%wt Yb.In addition,the grains of α-Al matrix are refined by Yb addition.Phase constitution of the alloy was analyzed by X-ray diffractometer（XRD） and energy dispersive spectroscopy（EDS）attached with SEM and mechanical properties were measured by hardness test.It is concluded that the Yb atoms are incorporated into the silicon by the adsorption at the solid-liquid growth front to cause the modification of eutectic silicon.Furthermore,the results of XRD and EDS analysis reveal that the Yb-containing phase forming in the alloys is Al_3Yb.

Manganese-Based Lithium-Ion Battery: Mn_(3)O_(4) Anode Versus LiNi_(0.5)Mn_(1.5)O_(4) Cathode

Lithium-ion batteries(LIBs)are widely used in portable consumer electronics,clean energy storage,and electric vehicle applications.However,challenges exist for LIBs,including high costs,safety issues,limited Li resources,and manufacturingrelated pollution.In this paper,a novel manganese-based lithium-ion battery with a LiNi_(0.5)Mn_(1.5)O_(4) ‖ Mn_(3)O_(4) structure is reported that is mainly composed of environmental friendly manganese compounds,where Mn_(3)O_(4) and LiNi_(0.5)Mn_(1.5)O_(4) (LNMO)are adopted as the anode and cathode materials,respectively.The proposed structure improves battery safety and reduce costs compared with current battery technology,provides comparable energy density with that of traditional graphite-based batteries.First,the characteristics and the electrochemical performances of the Mn_(3)O_(4) anode and the LNMO cathode are investigated separately against Li metal in half cell configurations,with promising performances being demonstrated by both electrodes.Then,a full cell structure with Mn_(3)O_(4) against LNMO is constructed that provides an average discharge voltage of 3.5 V and an initial specific capacity of 86.2 mA;h;g−1.More importantly,the electrochemical performance of the LNMO‖ Mn_(3)O_(4) full cell and its possible decay mechanisms are discussed systemically;and efficient strategies are proposed to further improve both the electrochemical performance of Mn_(3)O_(4) and the stability of LNMO.

Experimental and Performance Analyses on Elastomer-Strengthened Polyethylene Terephthalate/Glass Fiber Blends

Ethylene-methacrylate-glycidyl(EMG)copolymer is employed to strengthen polyethylene terephthalate(PET)/glass fiber(GF)blends.This paper starts from investigating the effects of various EMG contents on mechanical properties,thermal properties and fractured surface morphology of PET/GF blends.All of the above-mentioned properties own extreme limits of EMG concentration.The crystallization ability of the blends increases with an increment in EMG content,whereas the crystallinity keeps stable at a relatively high level of 0-20 wt.%EMG loading.The tension,bending and impact properties of PET blends are enhanced with the addition of a self-made three-dimensional hierarchical porous carbon sponge(3DC)based on an optimal additive amount.Results indicate that EMG possesses the capabilities of increasing the toughness of PET/GF blends remarkably and transforming the blends from brittle fracture to tough fracture.According to the results,the blends exhibit the best overall properties as the content of EMG reaches 10-15 wt.%.