A new traffic model with the consideration of coupling effect with two lanes

This paper introduces a new two-lane high-order continuum model by embedding the two delay time scales continuum traffic model presented by Xue (2003 Phys. Rev. E 68 066123) into the multi-lane model proposed by Daganzo (1997 Transpn. Res. B 31 83) with the consideration of the coupling effect between the vehicles of two lanes in instantaneous traffic situation and lane-change effect. In the novel model, the coupling effect of two lanes and phenomena of lane change, which were not discussed in Daganzo's model and Xue's model, are taken into account. Numerical simulation shows that it is in accordance with real traffic flow. This obviously indicates that the new phenomenon and behaviour are analogous results as single lane presented by Xue, and the proposed model is more reasonable on two lanes. Furthermore, the generation rate between two lanes is also investigated. The results show that the formation and diffusion of traffic shock wave can be better simulated on two lanes.     

A viscous continuum traffic flow model with consideration of the coupling effect for two-lane freeways

In this paper, the viscous continuum traffic flow model for a single lane is extended to the traffic flow for two-lane freeways. The proposed model is a higher-order continuum model considering the coupling and lane changing effects of the vehicles on two adjacent lanes. It results from integrating the Taylor series expansion of the viscous continuum traffic flow model proposed by Ge (2006 Physica A 371 667) into the multi-lane model presented by Daganzo (1997 Transpn. Res. B 31 83). Our proposed model may be used to describe non-anisotropic behaviour because of lane changing in multi-lane traffic. A linear stability analysis is given and the neutral stability condition is obtained. Also, issues related to lane changing, shock waves and rarefaction waves, local clustering and phase transition are investigated through a simulation experiment. The simulation results show that the proposed model is capable of explaining some particular traffic phenomena commonly observable in real world traffic flow.     

Multiple car-following model of traffic flow and numerical simulation

On the basis of the full velocity difference (FVD) model, an improved multiple car-following (MCF) model is proposed by taking into account multiple information inputs from preceding vehicles. The linear stability condition of the model is obtained by using the linear stability theory. Through nonlinear analysis, a modified Korteweg-de Vries equation is constructed and solved. The traffic jam can thus be described by the kink--antikink soliton solution for the mKdV equation. The improvement of this new model over the previous ones lies in the fact that it not only theoretically retains many strong points of the previous ones, but also performs more realistically than others in the dynamical evolution of congestion. Furthermore, numerical simulation of traffic dynamics shows that the proposed model can avoid the disadvantage of negative velocity that occurs at small sensitivity coefficients λ in the FVD model by adjusting the information on the multiple leading vehicles. No collision occurs and no unrealistic deceleration appears in the improved model.     

水位报警器模型的设计与制作

对水位报警器进行了简化和改进.实验中我们把杠杆模型、电路模型和物联系统相结合,采用单WiFi模块来接收电路发出的信号并向移动设备发出报警信息从而达到现场和移动设备都能发出水位警报的目的.本次实验产品是可受移动设备控制的简易水位报警装置.     

含铈钒基SCR催化剂脱硝性能及SO_2失活机理研究

掺杂Ce到V_2O_5-WO_3/TiO_2催化剂中,并研究其NH_3-SCR脱硝性能及SO_2失活机理。结果表明,V_1W_5Ce_6 Ti表现出更好的脱硝活性。采用XRD、BET、FT-IR、TG-DSC、XPS等手段表征分析Ce对催化剂性能的影响,并提出V_1W_5Ce_6Ti硫失活机理。结果表明,Ce、V、W都能在催化剂中很好的分散,当Ce的掺杂量达到8%时,有明显的CeO_2特征峰出现。在250℃时,V_1W_5Ti(U)表面会有NH4HSO4和(NH_4)_2SO_4生成。掺杂Ce后,V1W5Ce6Ti催化剂的Brnste酸位和表面化学吸附氧都增加。Ce与烟气中的SO_2和H_2O结合生成硫酸铈盐,从而抑制硫酸铵盐的生成。同时也阻断了Ce~(3+)与Ce~(4+)氧化还原循环,破坏V-O-Ce结构,造成催化剂活性下降。     

Preparation of Oxidized Organosolv Lignin⁃based Hydrophilic Sizing Agent and Its Application in Polypropylene北大核心CSCD

The interfacial compatibility of carbon fiber （CF） reinforced composites is the key factor to determine the comprehensive properties of the composites. The sizing agent plays an indispensable role between carbon fibers and matrix resins. Environmentally friendly hydrophilic sizing agent is is a hot research issue to be solved. In this work,the hydrophilic lignin-based sizing agent and carbon fiber reinforced polypropylene （PP） composites are prepared and studied. The lignin is ozonized to increase the reactive group. The obtained lignin reacts with epoxy group to prepare the oxidized organic solvent lignin based epoxy resin（OLBE）. OLBE reacts with alcohol amine and carboxylic acid to obtain the hydrophilic lignin-based sizing agent. KH550 is further added to balance the hygroscopicity of sizing agent. Finally,an oxidized organic solvent lignin-based hydrophilic sizing agent（OLBEDK）with excellent stability was prepared. The CF treated with 2. 5% solid content OLBEDK was only 3. 0 mg. The ILSS,Flexural strength,Flexural modulus and Impact strength of CF/PP composites are increased by 50. 8%,34. 2%,53. 7% and 127. 8%, respectively,compared with those of CF/PP composites without sizing. This is attributed to the π-π conjugation between the benzene ring of lignin and the carbon six-membered ring of CF,and the physical entanglement between the alkyl chain of KH550 and the molecular chain of PP,which enhances the interfacial interaction between CF and PP effectively. © 2022, Science Press (China). All rights reserved.     

电沉积Bi2Te3基薄膜的电化学阻抗谱研究

以不锈钢为基底,利用电化学沉积方法制备Bi2Te3基薄膜材料,并采用X射线衍射技术、电子探针微观分析等方法对薄膜进行结构和成分表征,通过电化学阻抗谱技术对不锈钢表面Bi2Te3的电化学沉积机理进行了初步探讨.结果表明Bi-Te和Bi-Te-Se体系具有相似的电化学沉积机理,即Bi3+和2HTeO+或H2SeO3首先被还原为Bi单质和Te或Se单质,然后Bi单质与Te或Se单质反应生成Bi2Te3基化合物,而Bi-Sb-Te体系中,2HTeO+首先被还原为Te单质,生成的Te再与Bi3+和Sb(III)反应生成Bi2Te3基化合物,三种体系的沉积都受电化学极化控制.     

市场化改革、经济战略与中国外汇储备积累:实证研究

对中国外汇储备成因的传统研究在很大程度上忽略了市场化进程因素对中国外汇储备积累的历史性和制度化影响。而外汇储备的决定因素分为两大类:战略性因素和制度性因素。战略性因素包括预防性需求、重商主义动机和机会成本;制度性因素包括对外贸易发展和市场化程度。通过一个改进的外汇储备需求函数模型对该因素进行实证研究,发现中国的外汇储备积累主要是外向型经济发展模式和市场化改革这一历史进程的客观结果,而非货币当局基于主观动机所追求的战略目标。     

液相外延生长超薄有源层AlxGa1—xAs／GaAs分别限制双异质结构激…

报道超薄有源层ＡｌｘＧａ１－ｘＡｓ／ＧａＡｓ分别限制双异质结构半导体激光器的液相外延的过程。讨论了过冷度、生长温度和降温速率对生长速率的影响。扫描电镜测得生长温度为６８０℃时，ＧａＡｓ有源层厚度可低至２５－３５ｎｍ。宽接触分别限制双异结构ＬＤｓ的室温连续阈值电流密度多在７００－８００Ａ／ｃｍ＾２。