汽车制动能量再生系统制动力分配研究

对汽车制动能量再生系统的制动力分配控制方法进行了研究,提出了基于ABS系统的防止后轮先抱死控制的车辆制动力分配控制方法,建立了相应的再生制动系统前后轴制动力分配控制策略模型,对控制模型进行了仿真分析,并在本课题组建立的汽车能量再生制动试验台上进行了在环仿真试验,结果表明,该再生制动系统制动力分配控制策略能够保证汽车良好制动性能,制动过程中增加了电机制动率,从而提高了汽车制动能量的回收率。

重型载货汽车长下坡制动控制策略

单一制动器温度升高出现制动热衰退现象后,其余制动器热负荷增加会影响整车制动效能,针对此问题提出了基于制动力观测模型的重型载货汽车长大下坡制动控制策略。首先,利用制动鼓温度能够准确表征制动力的特性建立了制动力观测模型;其次,依据整车制动器热衰退演变机理及车辆制动失稳机理,提出了结合散热量、地面附着率、滑移率及轴载的控制策略;然后,为了实现制动力的跟踪控制,建立了基于MPC制动力优化控制模型;为了验证提出的控制策略,建立了基于TruckSim和Matlab联合仿真模型;最后,进行低温制动工况、高温制动工况和基于滑移率的制动控制策略仿真验证。结果表明:低温工况能够抑制制动器温度的快速升高;高温工况能够降低制动器提前出现热衰退的风险,在保证整车制动效能的同时,预留了必要安全措施时间;基于滑移率的控制策略可以保证车辆制动稳定性。结果表明:所提出的控制策略既能相对均衡地控制制动器温度上升速度,又能避免因某一制动器温度快速升高而增加其余制动器热负荷,且保证制动稳定性,从而提高了重型载货汽车长下坡制动安全性。

基于动力性及制动性对SPMT液压平板车重载运输时道路极限坡度的研究

SPMT液压平板车作为主要的大件货物运输设备,坡道通过能力及坡道安全制动能力是其主要的性能参数。文中分别通过车辆行驶方程法和实验法分析得出SPMT通过坡道时车货总重、驱动轮总数及行驶道路极限坡度三者间的关系,并通过比较得到更适合实际使用的结论。同时通过对坡道制动力学模型的分析,得出SPMT重载坡道制动时车货总重、制动轮总数及制动道路极限坡度三者间的关系。通过对行驶极限坡度及制动极限坡度进行比较,得出SPMT载运时安全坡度的确定方法。

汽车制动能量再生系统制动力分配研究

对汽车制动能量再生系统的制动力分配控制方法进行了研究,提出了基于ABS系统的防止后轮先抱死控制的车辆制动力分配控制方法,建立了相应的再生制动系统前后轴制动力分配控制策略模型,对控制模型进行了仿真分析,并在本课题组建立的汽车能量再生制动试验台上进行了在环仿真试验,结果表明,该再生制动系统制动力分配控制策略能够保证汽车良好制动性能,制动过程中增加了电机制动率,从而提高了汽车制动能量的回收率。

EV再生制动系统的建模与仿真

电动汽车的一个重要的优点就是它具有再生制动能力 ,可以将制动过程中的动能回收 ,节约能源并增加汽车的续驶里程。文中对汽车中可再生制动的能量进行了分析 ,并提出了在电动汽车仿真中如何实现再生制动的建模和仿真。最后给出了仿真结果和再生制动系统在能量传递过程中的能量损失情况。

中低速磁浮列车液压制动系统仿真试验平台研究

为满足中低速磁浮列车液压制动系统试验需求,利用数据采集卡与MVB网络通信技术,基于C#开发了液压制动系统仿真试验平台,完成了速度与制动距离模型、制动力模型的建立及TCMS功能的模拟,测试验证了液压制动系统仿真试验平台的实用性。

Support vector machine based nonlinear model multi-step-ahead optimizing predictive control

A support vector machine with guadratic polynomial kernel function based nonlinear model multi-step-ahead optimizing predictive controller was presented. A support vector machine based predictive model was established by black-box identification. And a quadratic objective function with receding horizon was selected to obtain the controller output. By solving a nonlinear optimization problem with equality constraint of model output and boundary constraint of controller output using Nelder-Mead simplex direct search method, a sub-optimal control law was achieved in feature space. The effect of the controller was demonstrated on a recognized benchmark problem and a continuous-stirred tank reactor. The simulation results show that the multi-step-ahead predictive controller can be well applied to nonlinear system, with better performance in following reference trajectory and disturbance-rejection.

Modeling and control of hydraulic excavator's arm

In order to find a feasible way to control excavator’s arm and realize autonomous excavation, the dynamic model for the boom of excavator’s arm which was regarded as a planar manipulator with three degrees of freedom was constructed with Lagrange equation. The excavator was retrofitted with electrohydraulic proportional valves, associated sensors (three inclinometers) and a computer control system (the motion controller of EPEC). The full nonlinear mathematic model of electrohydraulic proportional system was achieved. A discontinuous projection based on an adaptive robust controller to approximate the nonlinear gain coefficient of the valve was presented to deal with the nonlinearity of the whole system, the error was dealt with by robust feedback and an adaptive robust controller was designed. The experiment results of the boom motion control show that, using the controller, good performance for tracking can be achieved, and the peak tracking error of boom angles is less than 4°.

Research on Dynamic Model's Building of Active Magnetic Suspension Systems

An experimental method is introduced in this paper to build the dynamics of AMSS (the active magnetic suspension system), which doesn’t depend on system’s physical parameters. The rotor can be reliably suspended under the unit feedback control system designed with the primary dynamic model obtained. Online identification in frequency domain is processed to give the precise model. Comparisons show that the experimental method is much closer to the precise model than the theoretic method based on magnetic circuit law. So this experimental method is a good choice to build the primary dynamic model of AMSS.

Effect of inlet temperature and equivalence ratio on HCCI engine performance fuelled with ethanol:Numerical investigation

A numerical model is presented to investigate the performance of homogeneous charge compression ignition(HCCI) engines fueled with ethanol. Two approaches are studied. On one hand, two-step reaction mechanisms with Arrhenius reaction rates are implemented in combustion chemistry modeling. On the other hand, a reduced mechanism containing important reactions of ethanol involving heat release rate and reaction rates compatible with experimental data is employed. Since controls of combustion phenomenon and ignition timing are the main issues of these engines, the effects of inlet temperature and equivalence ratio as the controlling factors on the operating parameters such as ignition timing, burn duration, in-cylinder temperature and pressure of HCCI engines are explored. The results show that the maximum predicted pressures for thermodynamic model are about 71.3×10~5 Pa and 79.79×10~5 Pa, and for chemical kinetic model, they are about 71.48×10~5 Pa and 78.123×10~5 Pa, fairly comparable with corresponding experimental values of 72×10~5 Pa and 78.7×10~5 Pa. It is observed that increasing the initial temperature advances the ignition timing, decreases the burn duration and increases the peak temperature and pressure. Moreover, the maximum temperature and pressure are associated with richer mixtures.

Fluid Flow Past a Circular Cylinder with Tandem Rod and Staggered Rod at Low Reynolds Number

The flow past a primary cylinder with one tandem control rod and one staggered control rod is simulated in this paper through solving the Navier-Stokes equations. Two examples are simulated to validate the model, and the results matched well with those of previous researches. The Reynolds number based on the diameter of the primary cylinder is 500. The diameter ratio between the control rod and the primary cylinder （d/D） is 0.25. It was found that the effect of the combination of one upstream tandem control rod and one staggered control rod on the hydrodynamics of the primary cylinder is a linear superposition of the effect of a corresponding single control rod, and the effect of the upstream tandem control rod is dominant at larger spacing ratios such as G/D=2. For the combination of a downstream tandem control rod and a staggered control rod, the effect of the control rods is different from that of the corresponding single control rod in the region of 0.2〈G/D〈0.5 ＆ 30°〈a〈120° and 0.9〈G/D〈1.4 ＆ 30°〈a〈50°, where the additional effect is obvious. In this case, the effect of the downstream tandem control rod is dominant at small spacing ratios （such as G/D=0.1）. At moderate spacing ratios such as G/D=0.4, the effects of the tandem control rod and the staggered control rod are comparable in both cases.

Thymoquinone and Poloxin are slow-irreversible inhibitors to human Polo-like kinase 1 Polo-box domain

Objective： To provide a kinetic model（s） and reveal the mechanism of thymoquinone and Poloxin blocking an emerging anti-cancer target, human Polo-like kinase 1 （hPlkl） Polo-box domain （PBD）. Methods： The binding kinetics was determined by using a fluorescence polarization based assay. The putative mechanism was examined with a competition test. Results： Thymoquinone follows a one-step binding with an association rate constant （k1） of 6.635× 10^3 L.mol^-1 min^-1.Poloxin fit a two-step binding with a dissociation constant （Ki） of 118 μmol/L for the intermediate complex and its isomerization rate （k4） of 0.131 5 minJ to form an irreversible adduct. No significant dissociation was observed for either ligand up to 13 h. The inhibitors responded insignificantly to the presence of Michael donors as hPIkl-PBD competitors. Conclusion： Thymoquinone and Poloxin are slow-tight ligands to the hPlkl-PBD with kinetic models distinct from each other. Michael addition as the mechanism is excluded.

An Improved Nonlinear Dynamic Inversion Method for Altitude and Attitude Control of Nano Quad-Rotors under Persistent Uncertainties

Nonlinear dynamic inversion(NDI)has been applied to the control law design of quad-rotors mainly thanks to its good robustness and simplicity of parameter tuning.However,the weakness of relying on accurate model greatly restrains its application on quad-rotors,especially nano quad-rotors(NQRs).NQRs are easy to be influenced by uncertainties such as model uncertainties(mainly from complicated aerodynamic interferences,strong coupling in roll-pitch-yaw channels and inaccurate aerodynamic prediction of rotors)and external uncertainties(mainly from winds or gusts),particularly persistent ones.Therefore,developing accurate model for altitude and attitude control of NQRs is difficult.To solve this problem,in this paper,an improved nonlinear dynamic inversion(INDI)method is developed,which can reject the above-mentioned uncertainties by estimating them and then counteracting in real time using linear extended state observer(LESO).Comparison with the traditional NDI(TNDI)method was carried out numerically,and the results show that,in coping with persistent uncertainties,the INDI-based method presents significant superiority.

Beam-track interaction of high-speed railway bridge with ballast track

Based on the construction bridge of Xiamen-Shenzhen high-speed railway(9-32 m simply-supported beam + 6×32 m continuous beam),the pier-beam-track finite element model,where the continuous beam of the ballast track and simply-supported beam are combined with each other,was established.The laws of the track stress,the pier longitudinal stress and the beam-track relative displacement were analyzed.The results show that reducing the longitudinal resistance can effectively reduce the track stress and the pier stress of the continuous beam,and increase the beam-track relative displacement.Increasing the rigid pier stiffness of continuous beam can reduce the track braking stress,increase the pier longitudinal stress and reduce the beam-track relative displacement,Increasing the rigid pier stiffness of simply-supported beam can reduce the track braking stress,the rigid pier longitudinal stress and the beam-track relative displacement.

Simulation Modeling of the Motion Control of a Two Degree of Freedom,Tendon Based,Parallel Manipulator in Operational Space Using MATLAB

In this paper a dynamical model of a two degree of freedom,tendon based,parallel manipulator (TBPM) system is proposed. The motion control methods of the TBPM system were designed. Using MATLAB,the motion control simulation of this model TBPM system was implemented in preparation for actual experiments. The results of the simulation demonstrated that the response time of the system was in a reasonable range,the motion behavior of the platform was stable and the tension forces acting on the tendons were in a safe range and acceptable. Furthermore,the parameters of the controllers were optimized using MATLAB and better results for the time response were obtained.

A Novel Exponential Kinetic Model for Casein Tryptic Hydrolysis to Prepare Active Peptides

The kinetics of casein tryptic hydrolysis to prepare activepeptides was investigated. Taking into account the reaction mechanismincluding single substrate hydrolysis, irreversible enzymeinactivation, and substrate inhibition, a set of exponentialequations was established to characterize the enzymatic hydrolysiscurves. The verification was carried out by a series of experimentalresults and indicated that the average regressive error was less than5/100. According to the proposed kinetic model, the kinetic constantsand thermodynamic constants of the reaction system were alsocalculated.

Dynamic Thermal Model and Temperature Control of Proton Exchange Membrane Fuel Cell Stack

A dynamic thermal transfer model of a proton exchange membrane fuel cell (PEMFC) stack is developed based on energy conservation in order to reach better temperature control of PEMFC stack. Considering its uncertain parameters and disturbance, we propose a robust adaptive controller based on backstepping algorithm of Lyaponov function. Numerical simulations indicate the validity of the proposed controller.

Ground movement mechanism in tectonic stress metal mines with steep structure planes

When mining metal mines with steep structure planes by the caving method,there is a mechanical model in which the horizontal stress on the rock mass is simplified as a column before surface subsidence.The model is used to deduce critical support load and limiting column length for a given horizontal stress and support pressure.Considering the impact of the column effect,a method is proposed to determine the movement of the ground and caving area in a mine.After surface subsidence,the horizontal stress on a surrounding rock mass can be simplified to a cantilever beam mechanical model.Expressions for its bending fracture length are deduced,and a method is given to determine its stability.On this basis,an explanation for the large ground movement and subsidence scope was given.A case study shows that the damage effect of column and cantilever beam is significant for ground movement in metal-ore mine,and an appropriate correction value should be applied when designing for its angle of ground movements.

Kinetics of Formic Acid-autocatalyzed Preparation of Performic Acid in Aqueous Phase

Performic acid （PFA） is an oxidant used in chemical processing, synthesis and bleaching. The macro kinetic models of synthesis, hydrolysis and decomposition of PFA were investigated via formic acid-autocatalyzed reaction. It was found that the intrinsic activation energies of PFA synthesis and hydrolysis were 75.2 kJ·mol^-1 and 40.4 kJ·mol^-1 respectively. The observed activation energy of PFA decomposition was 95.4 kJ·mol^-1. The experi-mental results indicated that the decomposition of PFA was liable to occur even at the ambient temperature. Both the spontaneous decomposition and the radical-introduced decomposition contributed to the decomposition of PFA.

Adaptive trajectory tracking control of two-wheeled self-balance robot

Wheeled mobile robot is one of the well-known nonholonomic systems. A two-wheeled sell-balance robot is taken as the research objective. This paper carried out a detailed force analysis of the robot and established a non-linear dynamics model. An adaptive tracking controller for the kinematic model of a nonhotonomic mobile robot with unknown parameters is also proposed. Using control Lyapunov function （CLF）, the controller＇s global asymptotic stability has been proven. The adaptive trajectory tracking controller decreases the disturbance in the course of tracking control and enhances the real-time control characteristics. The simulation result indicated that the wheeled mobile robot tracking can be effectively controlled.