A NOTE ON THE UNIQUENESSTHEOREM FOR STEADY-STATESEMICONDUCTOR EQUATIONS

In this note we investigate one-dimensional steady-state semicon-ductor devices. We proved the uniqueness of the solution to the unipolar de-vice problem with non-constant mobility.

The i-E Equations of Steady-state Voltammograms at Microdisk Electrodes

Based on the theories of conventional electrodes, as well as the properties of microdisk electrode, the i-E equations for chronoamperometry at disk microelectrode for reversible, quasi-reversible and irreversible systems are derived. Steady-state voltammograms for the oxidation of [Fe(CN)6]4- , Fe2+ and ascorbic acid were measured at a series of microdisk electrodes with different radii. The conventional log-plot shows that oxidations of [Fe(CN)6]4- and ascorbic acid are reversible and totally irreversible, respectively, but the oxidation of Fe2+ is reversible at larger radius microdisk electrodes and quasi-reversible at smaller radius microdisk electrodes. The application of the log-plot to the voltammograms yielded a straight line, its slope allows us to evaluate the charge transfer coefficient and the intercept gives values of the electron transfer rate constant.

A Posteriori Stabilized Sixth-Order Finite Volume Scheme with Adaptive Stencil Construction:Basics for the 1D Steady-State Hyperbolic Equations

We propose an adaptive stencil construction for high-order accurate finite volume schemes a posteriori stabilized devoted to solve one-dimensional steady-state hyperbolic equations.High accuracy(up to the sixth-order presently)is achieved,thanks to polynomial recon-structions while stability is provided with an a posteriori MOOD method which controls the cell polynomial degree for eliminating non-physical oscillations in the vicinity of dis-continuities.We supplemented this scheme with a stencil construction allowing to reduce even further the numerical dissipation.The stencil is shifted away from troubles(shocks,discontinuities,etc.)leading to less oscillating polynomial reconstructions.Experimented on linear,Burgers',and Euler equations,we demonstrate that the adaptive stencil technique manages to retrieve smooth solutions with optimal order of accuracy but also irregular ones without spurious oscillations.Moreover,we numerically show that the approach allows to reduce the dissipation still maintaining the essentially non-oscillatory behavior.

Moving-Water Equilibria Preserving HLL-Type Schemes for the Shallow Water Equations

We construct new HLL-type moving-water equilibria preserving upwind schemes for the one-dimensional Saint-Venant system of shallow water equations with nonflat bottom topography.The designed first-and secondorder schemes are tested on a number of numerical examples,in which we verify the well-balanced property as well as the ability of the proposed schemes to accurately capture small perturbations of moving-water steady states.

ABSTRACT CAPACITY OF REGIONS AND COMPACT EMBEDDING WITH APPLICATIONS

The weighted Sobolev-Lions type spaces W pl,γ（Ω; E0, E） = W pl,γ（Ω; E） ∩ Lp,γ （Ω; E0） are studied, where E0, E are two Banach spaces and E0 is continuously and densely embedded on E. A new concept of capacity of region Ω ∈ Rn in W pl,γ（; E0, E） is introduced. Several conditions in terms of capacity of region Ω and interpolations of E0 and E are found such that ensure the continuity and compactness of embedding operators. In particular, the most regular class of interpolation spaces Eα between E0 and E, depending of α and l, are found such that mixed differential operators Dα are bounded and compact from W pl,γ（Ω; E0, E） to Eα-valued Lp,γ spaces. In applications, the maximal regularity for differential-operator equations with parameters are studied.

EXISTENCE OF WEAK SOLUTIONS TO A DEGENERATE STEAD-STATE SEMICONDUCTOR EQUATIONS

In this paper, we consider a degenerate steady-state drift-diffusion model for semiconductors. The pressure function used in this paper is （）（s） = s~α（α 〉 1）. We present existence results for general nonlinear diffhsivities for the degenerate Dirichlet-Neumann mixed boundary value problem.

Semi-analytical steady-state response prediction for multi-dimensional quasi-Hamiltonian systems

The majority of nonlinear stochastic systems can be expressed as the quasi-Hamiltonian systems in science and engineering. Moreover, the corresponding Hamiltonian system offers two concepts of integrability and resonance that can fully describe the global relationship among the degrees-of-freedom(DOFs) of the system. In this work, an effective and promising approximate semi-analytical method is proposed for the steady-state response of multi-dimensional quasi-Hamiltonian systems. To be specific, the trial solution of the reduced Fokker–Plank–Kolmogorov(FPK) equation is obtained by using radial basis function(RBF) neural networks. Then, the residual generated by substituting the trial solution into the reduced FPK equation is considered, and a loss function is constructed by combining random sampling technique. The unknown weight coefficients are optimized by minimizing the loss function through the Lagrange multiplier method. Moreover, an efficient sampling strategy is employed to promote the implementation of algorithms. Finally, two numerical examples are studied in detail, and all the semi-analytical solutions are compared with Monte Carlo simulations(MCS) results. The results indicate that the complex nonlinear dynamic features of the system response can be captured through the proposed scheme accurately.

Secondary steady-state and time-periodic flows from a basic flow with square array of odd number of vortices

In a magnetohydrodynamic(MHD)driven fluid cell,a plane non-parallel flow in a square domain satisfying a free-slip boundary condition is examined.The energy dissipation of the flow is controlled by the viscosity and linear friction.The latter arises from the influence of the Hartmann bottom boundary layer in a three-dimensional(3D)MHD experiment in a square bottomed cell.The basic flow in this fluid system is a square eddy flow exhibiting a network of N~2 vortices rotating alternately in clockwise and anticlockwise directions.When N is odd,the instability of the flow gives rise to secondary steady-state flows and secondary time-periodic flows,exhibiting similar characteristics to those observed when N=3.For this reason,this study focuses on the instability of the square eddy flow of nine vortices.It is shown that there exist eight bi-critical values corresponding to the existence of eight neutral eigenfunction spaces.Especially,there exist non-real neutral eigenfunctions,which produce secondary time-periodic flows exhibiting vortices merging in an oscillatory manner.This Hopf bifurcation phenomenon has not been observed in earlier investigations.

Analytical solution of coupled non-linear second order differential equations in enzyme kinetics

The coupled system of non-linear second-order reaction differential equation in basic enzyme reaction is formulated and closed analytical ex-pressions for substrate and product concentra-tions are presented. Approximate analytical me-thod (He’s Homotopy perturbation method) is used to solve the coupled non-linear differential equations containing a non-linear term related to enzymatic reaction. Closed analytical expres-sions for substrate concentration, enzyme sub-strate concentration and product concentration have been derived in terms of dimensionless reaction diffusion parameters k, and us-ing perturbation method. These results are compared with simulation results and are found to be in good agreement. The obtained results are valid for the whole solution domain.

Simplified Criterion of Steady-State Stability of Electric Power Systems

In the paper the simplified criterion of a steady-state stability of electric power systems (EPS) is justified on the basis of Lyapunov functions in a quadratic form ensuring necessary and sufficient conditions of its performance. Upon that, the use of the node-voltage equations allows reducing study of a steady-state stability of complex EPS to study of the generator-bus system. The obtained results facilitate studies of a steady-state stability of the complex systems and have practical importance.

Comparative Study of Methods Used for a Capacity Estimation on Two Lane Undivided National Highways

In these days the traffic is expanding quickly and the activity conditions on Indian roads are exceedingly heterogeneous in nature because of variety of vehicles with various static and dynamic qualities.Due to unrestricted movements all fast and slow moving vehicles without any separation,the roads will face severe congestion and lower speeds.The greater part of national and state highways in India are two lane undivided roadway.These two lane highways achieve its greatest limit soon and require consistent up gradation to do this we need to estimate capacity of selected roads.In this present paper,attempts have been made to collect traffic volume for whole 7 days at national highways such as NH-206&NH-209.Also tried to compute PCU values at selected stretches on highways by using those values attempts has been made to estimate capacity and to compare those values with the regression equation values.Finally from the present study we got ADT at different section on highways,calculated PCU values as per Chandra’s method at various sections on highways and got marginal difference with the values recommended by IRC.It is found that with the increase in lane width,speed and radius substantially caused increased in PCU value.Also we developed linear regression equations to estimate capacity and compared those values with the values as we got using Chandra’s method.In most of the cases the error is observed to be less than 3%.The percentage error is in the range between 0.02 and 2.41 which is very marginal.Finally from the study it has been observed that increase in lane width and radius at curves obviously increases the capacity their by increases both comfort and safety of the road users.

煤吸附CO_(2)压缩因子快速计算模型研究

为研究Virial、V-d-W、R-K、S-R-K、P-R、童景山等6种工程常用气体状态方程中适合煤吸附CO_(2)压缩因子最优方程及快速计算模型,以3种不同变质程度煤样为研究对象,采用容量法实测了试验温度为30℃时应用以上6种方程所得煤的CO_(2)吸附量、CO_(2)吸附常数及吸附等温线。研究表明:与美国国家标准技术研究所(NIST)提供的CO_(2)压缩因子相比,采用Virial状态方程得到的CO_(2)压缩因子最大、绝对误差最小,为0.38%;吸附等温线拟合优度最高,CO_(2)吸附常数a值绝对值误差最小,确定出煤吸附CO_(2)压缩因子最优方程为Virial方程;同时,提出试验温度为30℃时,CO_(2)压缩因子一种简便快捷计算模型,经检验,该模型相对美国标准计算所得CO_(2)吸附常数a值绝对值误差最大不超过1%,且操作简便,快速精确。

超临界二氧化碳系统用箔片气体动压轴承静特性研究

超临界二氧化碳动力循环系统对实现节能减排的目标有着十分积极的作用。针对一种箔片气体动压轴承结构建立了计算模型,并通过拟合非理想状态气体超临界二氧化碳的密度与压力之间的关系,基于传热学模型和气体润滑能量方程分析了轴承气膜温升,结合实际运行过程中出现的湍流效应修正润滑气体雷诺方程、耦合力学分析模型和能量方程,分析S-CO_(2)介质箔片气体动压轴承的静特性,并与空气作为介质进行对比分析不同系统参数和湍流参数对轴承特性的影响规律。结果表明:相较于空气而言,使用超临界二氧化碳作为润滑介质的箔片气体动压轴承具有较高的承载力,而且在一定范围内随着轴承直径和宽度的增加、偏心率的上升、轴承间隙的减小、转速的提高等,轴承承载力均可以增大;对于湍流影响因素来说,在一定范围内随着局部雷诺数和湍流系数的增加、气体动力黏度和密度的提高、高温环境下环境温度的降低等,轴承承载力将会增大。

典型相关分析与结构方程模型方法的比较研究

典型相关分析(CCA)和结构方程模型(SEM)的应用日益广泛,但由于二者存在较大的相似性而常使研究者在使用过程中面临选择困难等问题,因而准确理解和区分二者之间的差异至关重要。文章基于SPSS和AMOS操作环境对典型相关分析和结构方程模型在函数式、基本图形、二阶因素、中介效应及使用条件等方面进行系统性比较,研究结果表明:(1)CCA可以进行线性组合计算,直接计算一个潜变量与另一组显变量的关系,能有效处理二阶因素计算问题。(2)SEM可以同时考虑多个潜变量之间的关系、计算和呈现误差方差和残差、准确地计算和展示中介效应、运用辅助性标准来判断模型适配度并通过调整变量之间的逻辑联系来修正模型,其输出结果全面而精确。(3)CCA适用于含有两个潜变量的简单模型,而SEM适用于含有多个潜变量的复杂模型。在特定条件下,可以结合使用CCA和SEM,或用CCA代替SEM。

基于结构方程模型的绿色铁路建造能力形成机理研究

在“碳达峰碳中和”双碳目标驱动下,铁路的绿色转型势在必行,然而目前铁路工程企业绿色铁路建造能力尚显不足,究其原因是由于绿色铁路建造能力建设目标不明确、依据不充分。首先,通过文献分析归纳出绿色铁路建造能力的4个构成维度,筛选识别出5类影响因素和23个影响因素指标。其次,根据绿色铁路建造领域相关研究成果提出影响因素作用的研究假设,建立结构方程概念模型。最后,通过调查问卷进行数据收集,进行理论模型的拟合和检验,再基于拟合结果分析揭示各影响因素对企业绿色铁路建造能力的作用效应。研究结果表明:企业技术发展及人才建设水平、行业发展水平、企业内部绿色发展水平、企业综合管理水平和政府推力对绿色铁路建造能力均有显著正向影响,且影响效应依次递减;政府推力和行业发展水平仅对绿色铁路建造能力产生间接影响,企业内部绿色发展水平、企业综合管理水平和企业技术发展及人才建设水平仅起直接作用。研究揭示了绿色铁路建造能力的形成机理,为提高企业绿色铁路建造能力提供理论依据,有助于提高铁路工程企业对绿色铁路建造能力的认知水平,帮助其快速实现绿色转型。

CPA方程计算醇、水的比热容性质

针对立方型附加缔合项(CPA)状态方程(EoS)对比热容的计算精度不高的问题,采用11种包含不同性质的参数计算方法研究了CPA方程对极性缔合流体甲醇、乙醇、水比热容的计算精度。计算结果表明:不考虑比热容时,CPA方程的参数计算必须考虑蒸汽压性质,且蒸汽压计算精度越高,方程对液相比热容的预测精度越高;在参数计算中加入比热容后,CPA方程无法同时准确描述所有比热容性质,其中对液相比定压热容的计算精度最高;在参数计算过程中比热容性质只考虑液相比定压热容时,方程对蒸汽压、各相密度及液相比定压热容的平均绝对相对偏差都在3%及以内。

Capacity Allocation of Renewable Energy Sources Considering Complementarity

The outputs of renewable energy sources(RESs)are inherently variable and uncertain,such as wind power(WP)and photovoltaic(PV).However,the outputs of various types of RESs in different regions are complementary.If the capacity of RESs could be properly allocated during system planning,variability of the total output could be reduced.Consequently,system reliability and renewable energy(RE)consumption could be improved.This paper proposes an analytical model for optimal complementary capacity allocation of RESs to decrease variability of the total output.The model considers the capacity ratio of RESs as decision variables and the coefficient of variation(CV)of the total output as the objective function.The proposed approach transforms the single-level optimization model into a bilevel optimization model and derives an analytical equation that can directly calculate the optimal complementary capacity ratio(OCCR)of system RESs.Case studies on wind and solar farms in Xinjiang and Qinghai,China,are performed to verify the effectiveness of the proposed analytical allocation method.

医疗挤兑危机视域下政府危机管理机制分析

[目的]构建医疗挤兑危机视域下政府危机管理机制的理论框架,并通过样本数据对模型进行实证检验,探讨各节点之间的关系,为提升政府危机管理能力提供参考依据。[方法]本研究采用回顾性调查的方法对2019年末至2020年初居住在武汉且了解政府危机管理状况的人群进行网络问卷调查,应用AMOS 24.0软件构建医疗挤兑危机视域下政府危机管理机制模型。[结果]模型拟合度较好[卡方自由度比值(CMIN/DF)=1.954,渐进残差均方和平方根(RMSEA)=0.044,比较适配指数(CFI)=0.987]。模型中风险防控体系构建水平、政府危机监测预警能力、政府应急处置能力分别对政府危机管理能力产生直接效应,效应值分别为0.365、0.385和0.265;风险防控体系构建水平和危机监测预警能力对政府危机管理能力也起到间接效应,效应值为0.206和0.109。[结论]政府危机管理机制模型在理论和实证中结果良好,较好地反映出各变量之间的影响关系,对政府危机管理能力的提升提供了理论支撑。

基于QFD和Lanchester方程的有人/无人机协同保障能力

当前由于有人/无人机协同作战的常态化和规模化运用,对有人/无人机协同保障能力的要求也越来越高。针对现代化战争的作战特点,基于QFD方法分析当前有人/无人机协同保障能力需求指标,基于Lanchester方程优化构建有人/无人机协同保障数学模型,仿真验证得到各个需求指标的影响程度,从而提出针对性的训练措施及方法。通过算例验证方法的科学性,实验结果证明所提方法可以对有人/无人机协同保障的运用提供有益借鉴和参考。

范德瓦尔斯气体的状态方程与多方过程

范德瓦尔斯气体模型是对理想气体模型的一种修正,很多普通物理教材和文献对范德瓦尔斯气体的状态方程进行了讨论,但对过程方程很少讨论,尤其是结合物理图像的讨论。本文结合数学表达式和相关物理图像首先讨论了范德瓦尔斯气体的状态方程,并代入实际气体进行分析,再探究特殊的热力学过程,进而讨论一般的热力学过程,并与理想气体进行比较。讨论在热力学过程中功、内能、热量、热容量以及多方指数的变化,并结合相关实际应用,可以加深对范德瓦尔斯气体相关物理图像的理解。