具有振动位势的二阶带强迫项、阻尼项的时滞微分方程的振动性

讨论了具有振动位势的二阶微分方程(k(t)x′(t))′+τ(t)x′(t)+p(t)x(τ(t))+q(t)x(σ(t))=e(t),利用其线性近似方程(k(t)x′(t))′+p(t)x(τ(t))+q(t)x(σ(t))=e(t)的振动性,给出了方程解振动的一个充分条件,所得结果推广了文献[Computer andMathematics with Applications,2006,51:1395-1404]的相关结果.     

一类中立型积分微分方程周期解的存在性和唯一性

考虑具连续时滞和离散时滞的中立型积分微分方程d/dt[x(t) q∑j=1ej(t)x(t-δj(t))]=A(t,x(t))x(t ∫t-∞ C(t,s)x(s)ds 1∑i=1gi(t,x(t-Υi(t))) b(t)和d/dt[x(t) q∑j=1ej(t)x(t-δj(t))]=A(t)x(t) ∫t-∞C(t,s)x(s)ds 1∑j=1gi(t,x(t-Υi(t))) b(t)周期解的存在性和唯一性问题,利用线性系统指数型二分性理论和泛函分析方法,并通过技巧性代换获得了保证中立型系统周期解存在性和唯一性的充分性条件,从而避开了在研究中立型系统时x(t-δ)时滞项的导数x1(t-δ)的出现,推广了相关文献的主要结果.     

二阶非齐次时滞微分方程解的平方可积性与有界性

借助于辅助泛函,得到了二阶非齐次非线性时滞微分方程(r(t)x′(t))′ p(t)x′(t) q1(t)x(t) q2(t)x(h(t))=f(t,x(t))所有解均平方可积及所有解都有界的判定准则     

具有变量时滞的周期微分系统的周期解

本文考虑周期微分系统x(t) =A(t,x(t- r1(t) ) ) x(t) + f (t,x (t- r2 (t) ) )的 T-周期解的存在性问题 ,其中 (t,x)∈R× Rn,A(t,x)是 n× n连续矩阵函数 ,f(t,x)是 n维连续向量函数 ,时滞 ri(t) (i=1,2 )是连续函数 ,且 A(t+ T,x) =A(t,x) ,f(t+ T,x) =f(t,x) ,ri(t+ T) =ri(t) (i=1,2 ) ,常数T>0 .本文利用不动点方法 ,建立了保证系统存在 T-周期解的充分条件 ,推广了文 [1- 3]的相关结果 .     

二阶非齐泛函微分方程解的有界性

本文借助辅助函数和不等式得到了二阶非齐次泛函微分方程(r(t) x′(t) )′+p(t) x′(t) +q1(t) x(t) +q2 (t) x(t-τ) +g(t,x) =f (t)的一切解均有界的判定方法     

一类具分布时滞的微分方程的正周期解的存在性与多解性

讨论具分布时滞的微分方程x′(t)=-a(t,x)x(t)+∫-0τf(t,r,x(t+r))dr,x′(t)=a(t,x)x(t)-∫0-τf(t,r,x(t+r))drx′(t)=-g(t,x(t))+∫0-τf(t,r,x(t+r))dr,x′(t)=g(t,x(t))-∫0-τf(t,r,x(t+r))dr正周期解问题,利用锥不动点定理,获得了这类问题正解存在性和多重性的充分条件,推广了已有文献的相关结果.     

具有偏差变元的Liénard型方程的周期解

本文利用重合度理论研究了一类具偏差变元的Liénard型方程x″(t) f_1(t,x(t))|x′(t)|~2 f_2(t,x(t),x(t-τ_0(t)))x′(t) g(t,x(t-τ_1(t)))=p(t)获得了该方程存在ω-周期解的若干新结论,改进和推广了已有文献中的相关结果．     

一类有偏差变元的泛函微分方程的2π周期解

用迭合度理论研究一类有偏差变元的泛函微分方程x“(t) f(x(t))x‘(t) bx(t) g(x(t-τ1(t,x(t),x‘(t))),……,x(t,x(t),x‘(t)))=p(t)的2π周期解的存在性,从本质上改进和推广了张正球等人（1998年）的相应结果。     

二阶含阻尼项可化为“积分小”系数的微分方程解的振动性质

本文考虑下列二阶微分方程 (r(t)x′(t))′ q(t)x′(t) p(t)x(t)=0. (1) 和 (r(t)x′(t))′ q(t)x′(t) p(t)f(x(g(t)))=0 (2)解的振动性质。我们给出了方程(1)非振动解存在的充要条件和方程(2)存在振动解的充分判据。     

一类带有阻尼项的二阶半线性中立型微分方程解的振动准则

本文研究了—类带有阻尼项的二阶半线性中立型微分方程(r(t)φ(x(t))|(x(t)+p(t)x(σ(t)))′|α-1(x(t)+p(t)x(σ(t))′)′+φ(x(t),x′(t)+q0(t)|x(Τ0(t))|α-1x(Τ0(t))+nΣi=1qi(t)|x(Τi(t))|βi-1x(Τi(t))=0的解的性质,其中n是—个偶数,利用一些新的技巧,我们获得了方程解的振动的一些充分条件,并且给出例子阐述我们所得的结论.     

复杂装备研制协调超网络均衡与实现路径

复杂装备研制主体间呈现社会关系、合作关系、协调关系等网络关系,并且相互影响相互作用,其影响复杂装备研制的重要参数。为有效描述在资源环境约束下制造商和供应商的关系,探讨复杂装备研制协调机理与实现路径,本文利用超网络方法,设计了相互影响、相互作用的社会关系网络、协调网络和合作网络的复杂装备研制协调超网络,并将社会关系水平、协调度和合作水平作为超网络的3个决策变量,建立基于关系价值最大、协调成本最低、协调风险最小、合作收益最大、合作风险最小和成本最小等不同偏好下的多目标最优决策模型,构建了复杂装备研制超网络均衡模型,并利用其探讨超网络均衡和实现路径。     

城市老旧居住小区交通环境评价指标与评价方法

定量的评判城市老旧居住小区整体交通环境质量并进而科学有效的提出老旧小区交通环境更新与改善措施,对城市老旧居住小区交通环境进行了调查,明确了老旧居住小区存在的突出交通问题,并提出了城市老旧居住小区交通环境评价的指标体系,包括行人跨路出行指数、无人行道路段长度占比、停车泊位供需比、路内非法停车占比、平均停车步行距离、泊位数量户数比、人均步行空间、无障碍通道、盲道设置比例、非机动车泊位供需比、地面停放车辆数小区面积比、外部穿行交通周转量小区面积比等。并给出了具体指标的计算方法与获得办法。以长沙市四个典型老旧居住小区为例,对评价方法进行了论证,并得到城市老旧居住小区存在的一般问题,包括人车混杂、人车交织现象严重,停车泊位短缺、车辆乱停乱放,交通设施、特别是弱势群体交通设施缺乏。给出的评价指标、评价方法与结论可为城市老旧小区改造更新,特别是其中很重要的交通环境更新提供决策依据。     

乡村绿色生态旅游适宜等级VIKOR评估方法

针对乡村绿色生态旅游特征,并考虑旅游者个体感受与群体效益,本文从乡村绿色生态旅游开发与适宜评级概念出发,提出乡村绿色生态旅游适宜等级VIKOR评估模型与方法。首先,从等级评估的概念与内涵出发,刻画乡村绿色生态旅游适宜评级问题,避免混淆旅游适宜评级和排序两个本质不同的问题。然后,构建乡村绿色生态旅游适宜等级评估指标及隶属函数,提出评估指标的熵权确定方法。其次,提出乡村绿色生态旅游适宜等级VIKOR评估模型与二元语义等级评估方法。最后,通过案例研究和比较分析,说明本文所提模型与方法的合理性、可行性与实用性。     

网络团购环境下基于电子中介的商品交易优化模型

在网络团购环境下,如何考虑顾客、商家和电子中介三方主体的利益并实现商品交易最优化,这是一个值得关注的研究问题。本文针对基于电子中介的网络团购商品交易问题,依据商家与电子中介事先商定的团购商品的交易数量区间、交易数量折扣以及顾客和商家分别提交的商品的报价和保留价,在考虑顾客、商家和电子中介三方利益最大化的前提下,构建了多目标商品交易优化模型;进一步地,将多目标优化模型转化为单目标优化模型,并给出了求解优化模型的遗传算法。最后,通过一个算例说明了本文构建的模型及其求解算法的可行性和有效性。     

道路维修施工路段交通分流信控优化模型

针对道路维修施工期间常采用的部分路面封闭施工且利用辅路进行分流的情形,探讨了交通分流信控优化模型。借助交通流波动理论,分析了施工路段及其前后车流拥挤排队及疏散特征和规律,分析了对车流进行控制需满足的约束,并分析了车流的延误计算公式。以总的车辆行驶时间最小化目标,原路径及分流路径的绿时分配及信号周期为优化参数,考虑交通分流控制的各种约束,建立了道路施工路段交通分流信控优化模型。分析了该模型属于非凸问题,因此提出了一种近似求解最优解的办法。通过一个示例对模型和求解算法进行了验证,并对一些规律性结果进行了分析。     

On the use of history of mathematics: an introduction to Galileo's study of free fall motion

In this paper, we report on an experimental activity for discussing the concepts of speed, instantaneous speed and acceleration, generally introduced in first year university courses of calculus or physics. Rather than developing the ideas of calculus and using them to explain these basic concepts for the study of motion, we led 82 first year university students through Galileo's experiments designed to investigate the motion of falling bodies, and his geometrical explanation of his results, via simple dynamic geometric applets designed with GeoGebra. Our goal was to enhance the students’ development of mathematical thinking. Through a scholarship of teaching and learning study design, we captured data from students before, during and after the activity. Findings suggest that the historical development presented to the students helped to show the growth and evolution of the ideas and made visible authentic ways of thinking mathematically. Importantly, the activity prompted students to question and rethink what they knew about speed and acceleration, and also to appreciate the novel concepts of instantaneous speed and acceleration at which Galileo arrived.     

Interpreting linear systems of equalities and inequalities. Application to the water supply problem

This paper shows how the mathematical and the engineering points of view are complementary and help to model real problems that can be stated as systems of linear equations and inequalities. The paper is devoted to point out these relations and making them explicit for the readers to realize about the new possibilities that arise when contemplating the compatibility conditions or the set of general solutions from the dual perspective. After reviewing an orthogonally based powerful algorithm to analyse the compatibility of linear systems of equations and solving them, a water supply problem is used to illustrate its mathematical and engineering multiple aspects, including the optimal statement of the problem in terms of an adequate selection and numbering of equations and unknowns, an analysis of the compatibility conditions and a physical interpretation of the general solution, together with that of each individual generators of the affine space. The possibilities of removing unknowns without altering the compatibility of the problem is also analysed. Next, the Γ‐algorithm to analyse the compatibility of linear systems of inequalities and solving them is described and then, the water supply problem is revisited adding some constraints, such as capacity limits for the pipes and retention valves, and discussed as to how they affect the resulting general solution and other aspects. Finally, some conclusions are derived. Copyright © 2005 John Wiley & Sons, Ltd.     

利益相关者视角下公路货运超限超载的对策研究——基于演化博弈模型和仿真分析

为有效遏制公路货运超限超载现象,深化交通执法领域的“放管服”改革,本研究针对运输者、稽查人员和交管部门等利益相关者,建立三方演化博弈模型,研究超限超载运输中各利益主体的决策演化过程,并对稳定策略的演化路径进行仿真分析,比较不同参数组合下不同政策力度的治理效果。研究发现,提高超限超载运输的处罚系数可以明显规范运输者的行为;管理成本越低,监管部门的策略越可能向积极监管的方向演化;三方博弈系统存在两种可能的演化稳定策略,加重对稽查人员消极执法行为的处罚、加大资金设备投入能够提高系统向最优状态演化的概率。     

Creep of polymer concrete in the nonlinear region

Two polyester-based polymer concretes with various volume content of diabase as an extender and aggregate are tested in creep under compression at different stress levels. The phenomenological and structural approaches are both used to analyze the experimental data. Common features of changes in the instantaneous and creep compliances are clarified, and a phenomenological creep model which accounts for the changes in the instantaneous compliance and in the retardation spectrum depending on the stress level is developed. It is shown that the model can be used to describe the experimental results of stress relaxation and creep under repeated loading. Modeling of the composite structure and subsequent solution of the optimization problem confirm the possibility of the existence of an interphase layer more compliant than the binder. A direct correlation between the interphase volume content and the instantaneous compliance of the composite is revealed. It is found that the distinction in nonlinearity of the viscoelastic behavior of the two polymer concretes under investigation can be due to the difference in their porosity. Submitted to the 11th International Conference on Mechanics of Composite Materials (Riga, June 11–15, 2000.) Translated from Mekhanika Kompozitnykh Materialov, Vol. 36, No. 2, pp. 147–164, 2000.     

激光辐照下圆薄板的动态屈曲研究

对强激光辐照下薄板（铜片）的动态热失稳过程进行了分析，得出了简支圆薄板在热冲击下发生的屈曲及后屈曲过程，并给出了临界激光功率密度与薄板厚径比的关系曲线，方法计入了温度分布、惯性项和缺陷大小对于失稳过程的影响。这一工作有利于人们对强激光引起的硬目标破坏机理的认识。