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Lane changing analysis for two-lane traffic flow

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Acta Mechanica sinica 2007年第1期23卷 49-54页

作者： Tieqiao Tang Haijun Huang s. C. Wong Rui Jiang Department of Automobile Engineering Beihang University Beijing 100083 China school of Management Beihang University Beijing 100083 China Department of Civil Engineering The University of Hong Kong Pokfulam Road Hong Kong China school of Engineering science University of Science and Technology of China Hefei 230026 China

In this paper, the two-lane traffic are studied by using the lane-changing rules in the car-following models. The simulation show that the frequent lane changing occurs when the lateral distance in car following activities is considered and it gives rise to oscillating waves. In contrast, if the lateral distance is not considered （or considered occasionally）, the lane changing appears infrequently and soliton waves occurs. This implies that the stabilization mechanism no longer functions when the lane changing is permitted. since the oscillating and soliton waves correspond to the unstable and metastable flow regimes, respectively, our study verifies that a phase transition may occur as a result of the lane changing.

关键词： Traffic flow Lane-changing rules Car-following models Flow stability

A car-following model with the anticipation effect of potential lane changing

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Acta Mechanica sinica 2008年第4期24卷 399-407页

作者： Tieqiao Tang Haijun Huang s. C. Wong Rui Jiang school of Transportation science and Engineering Beihang University Beijing 100083 China school of Economics and Management Beihang UniversityBeijing 100083 China Department of Civil Engineering The University of Hong KongPokfulam Road Hong Kong China school of Engineering science University of Science and Technology of ChinaHefei 230026 China

In this paper, a new car-following model is presented, taking into account the anticipation of potential lane changing by the leading vehicle. The stability condition of the model is obtained by using the linear stability theory. The modified Korteweg-de Vries （KdV） equation is constructed and solved, and three types of traffic flow in the headway-sensitivity space, namely stable, metastable and unstable ones, are classified. Both the analytical and simu- lation results show that anxiety about lane changing does indeed have an influence on driving behavior and that a consideration of lane changing probability in the car-following model could stabilize traffic flows. The quantitative relationship between stability improvement and lane changing probability is also investigated.

关键词： Car-following model· Lane changing probability·stability

spinless particles in the field of unequal scalar vector Yukawa potentials

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Chinese Physics B 2013年第4期22卷 81-86页

作者： M.Hamzavi s.M.Ikhdair K.E.Thylwe Department of science and Engineering Abhar Branch Islamic Azad University Abhar Iran Department of Electrical and Electronic Engineering Near East University 922022 Nicosia North Cyprus Mersin 10 Turkey Department of Physics Faculty of Science An-Najah National University Nablus West Bank Palestine KTH-Mechanics Royal Institute of Technology S-100 44 Stockholm Sweden

We present analytical bound state solutions of the spin-zero Klein–Gordon （KG） particles in the field of unequal mix-ture of scalar and vector Yukawa potentials within the framework of the approximation scheme to the centrifugal potential term for any arbitrary l-state. The approximate energy eigenvalues and unnormalized wave functions are obtained in closed forms using a simple shortcut of the Nikiforov–Uvarov （NU） method. Further, we solve the KG–Yukawa problem for its exact numerical energy eigenvalues via the amplitude phase （AP） method to test the accuracy of the present solutions found by using the NU method. Our numerical tests using energy calculations demonstrate the existence of inter-dimensional degeneracy amongst the energy states of the KG–Yukawa problem. The dependence of the energy on the dimension D is numerically discussed for spatial dimensions D = 2–6.

关键词： Klein–Gordon equation Yukawa potential D-dimensional space Nikiforov–Uvarov and amplitude phase methods

Heat transfer in a porous saturated wavy channel with asymmetric convective boundary conditions

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Journal of Central south University 2015年第1期22卷 392-401页

作者： Q.Hussain s.Asghar T.Hayat A.Alsaedi Department of Mathematics COMSATS Institute of Information Technology Department of Mathematics Faculty of Science King Abdulaziz University Department of Mathematics Quaid-I-Azam University 45320

The viscous flow in a wavy channel with convective boundary conditions is investigated. The channel is filled with a porous viscous fluid. Two cases of equal and different external convection coefficients on the walls are taken into account. Effect of viscous dissipation is also considered. The governing equations are derived employing long wavelength and low Reynolds number approximations. Exact closed form solutions are obtained for the simplified equations. Important physical features for peristaltic flow caused by the wavy wave are pumping, trapping and heat transfer rate at the channel walls. These are discussed one by one in depth and detail through graphical illustrations. special attention has been given to the effects of convective boundary conditions. The results show that for Bi1≠Bi2, there exists a critical value of Brinkman number Brc at which the temperatures of both the walls become equal. And, for Bi1>Bi2 and Br>Brc, the temperature of the cold wall exceeds the temperature of hot wall.

关键词： peristalsis heat transfer porous medium convective boundary conditions

Review of deployment technology for tethered satellite systems

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Acta Mechanica sinica 2018年第4期34卷 754-768页

作者： B.s.Yu H.Wen D.P.Jin state Key Laboratory of Mechanics and Control of Mechanical structures Nanjing University of Aeronautics and Astronautics

Tethered satellite systems（Tsss） have attracted significant attention due to their potential and valuable applications for scientific research. With the development of various launched on-orbit missions, the deployment of tethers is considered a crucial technology for operation of a Tss. Both past orbiting experiments and numerical results have shown that oscillations of the deployed tether due to the Coriolis force and environmental perturbations are inevitable and that the impact between the space tether and end-body at the end of the deployment process leads to complicated nonlinear phenomena. Hence, a set of suitable control methods plays a fundamental role in tether deployment. This review article summarizes previous work on aspects of the dynamics, control, and ground-based experiments of tether deployment. The relevant basic principles, analytical expressions, simulation cases, and experimental results are presented as well.

关键词： Tethered satellite Deployment Dynamics Control Experiment

Radiative Lifetime Measurements of Even-Parity Levels of singly Ionized Erbium

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Chinese Physics Letters 2004年第9期21卷 1720-1722页

作者：徐淮良蒋红梅刘倩蒋占魁 s.svanberg DepartmentofPhysics YantaiUniversityYantai264005 DepartmentofPhysics JilinUniversityChangchun130023 DepartmentofPhysics LundInstituteofTechnologyPOBox118S-221O0LundSweden

Radiative lifetime measurements were performed by time-resolved laser-induced fluorescence (LIF) technique for eight even-parity levels of the astrophysically important ion Er+ over the energy range from 33753 to 55317cm−1. Free erbium ions were generated by a laser-induced plasma. A narrow bandwidth UV laser pulse (1ns) was employed to populate selectively the short-lived upper levels, and the lifetime value were evaluated from the time-resolved fluorescence signals. The lifetimes reported fall in the range of 3–35ns with the experimental accuracy 5–8%.

关键词： Erbium

Conversion of an atomic to a molecular argon ion and low pressure argon relaxation

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Chinese Physics B 2016年第1期25卷 697-705页

作者： M N stankov A P Jovanovie V Lj Markovic s N stamenkovic Department of Physics Faculty of Sciences and MathematicsUniversity of Ni Viegradska 33Ni 18001Serbia

The dominant process in relaxation of DC glow discharge between two plane parallel electrodes in argon at pressure 200 Pa is analyzed by measuring the breakdown time delay and by analytical and numerical models. By using the approx- imate analytical model it is found that the relaxation in a range from 20 to 60 ms in afterglow is dominated by Ar＋ ions, produced by atomic-to-molecular conversion of Ar＋ ions in the first several milliseconds after the cessation of the discharge. This conversion is confirmed by the presence of double-Gaussian distribution for the formative time delay, as well as con- version maxima in a set of memory curves measured in different conditions. Finally, the numerical one-dimensional （1D） model for determining the number densities of dominant particles in stationary DC glow discharge and two-dimensional （2D） model for the relaxation are used to confirm the previous assumptions and to determine the corresponding collision and transport coefficients of dominant species and processes.

关键词： argon discharge afterglow relaxation fluid model plasma reactions

Mathematical model of micropolar fluid in two-phase immiscible fluid flow through porous channel

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Applied Mathematics and Mechanics(English Edition) 2018年第7期39卷 993-1006页

作者： P.K.YADAV s.JAIsWAL B.D.sHARMA Department of Mathematics Motilal Nehru National Institute of Technology Allahabad

This paper is concerned with the flow of two immiscible fluids through a porous horizontal channel. The fluid in the upper region is the micropolar fluid/the Eringen fluid, and the fluid in the lower region is the Newtonian viscous fluid. The flow is driven by a constant pressure gradient. The presence of micropolar fluids introduces additional rotational parameters. Also, the porous material considered in both regions has two different permeabilities. A direct method is used to obtain the analytical solu- tion of the concerned problem. In the present problem, the effects of the couple stress, the micropolarity parameter, the viscosity ratio, and the permeability on the velocity profile and the microrotational velocity are discussed. It is found that all the physical parameters play an important role in controlling the translational velocity profile and the microrotational velocity. In addition, numerical values of the different flow parameters are computed. The effects of the different flow parameters on the flow rate and the wall shear stress are also discussed graphically.

关键词： micropolar fluid immiscible fluid porous medium couple stress microp=olarity parameter

Numerical simulation of Vortex Engine Flow Field:One Phase and Two Phases

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Journal of Thermal science 2009年第3期18卷 226-234页

作者： A.F.Najafi s.D.saemi M.H.saidi Department of Energy Engineering Power and Water University of Technology Department of Mechanical Engineering Sharif University of Technology

Aiming at improving efficiency in combustion systems, the study on droplet behavior and its trajectory is of crucialimportance. Vortex engine is a kind of internal combustion engine which uses swirl flow to achieve highercombustion efficiency. One of the important advantages of designing vortex engine is to reduce the temperatureof walls by confining the combustion products in the inner vortex. The scopes of this investigation are to studyvortex engine flow field as well as effective parameters on fuel droplet behavior such as droplet diameter, dropletinitial velocity and inlet velocity of the flow field. The flow field is simulated using Reynolds stress TransportModel (RsM). The Eulerian-Lagrangian method and the one-way coupling approach are employed to simulatetwo phase flow and dispersed phase in the chamber, respectively. A new method, based on computing pressureforce exerted on the droplet surface, is introduced to determine the distinction between using one-way andtwo-way coupling approaches. The results showed that the droplets with smaller diameter are more likely to followthe flow stream lines than bigger droplets, thus evaporate completely in the chamber. Moreover, droplets withgreater initial velocity have higher evaporation rate, yielding the existence of evaporation and combustion in theinner vortex. Additionally, the higher inlet velocity of continuous phase results in higher centrifugal force, leadsdroplets in question to deviate towards the wall faster.

关键词： Vortex Engine swirl Flow Lagrangian Approach Fuel Droplet