组合出行方式下的混合均衡分配模型及求解算法

在现代城市的出行活动中,人们往往需要换乘一种或多种交通工具才能到达目的地,这种出行方式称为组合出行方式．在组合出行方式下,人们除了选择路径,还要选择换乘站点．我们研究了组合出行方式下的混合均衡分配问题,提出了与均衡分配条件等价的变分不等式模型,设计了求解模型的算法,并用一个算例说明了模型和算法的有效性．     

居民生活私人交通碳排放驱动因素的“三级分解”模型

突破以往采用难以保证精确性估算数据的局限,根据居民生活私人交通所消耗的能源种类,利用官方统计年鉴中的数据,在保证数据真实性的基础上,基于扩展的IPAT与LMDI模型,构建一个包含居民私人交通碳排放强度、碳排放结构、交通消费倾向、收入、家庭规模与户数6个因素的居民私人交通碳排放驱动因素的"三级分解模型",对居民生活私人碳排放及其驱动因素进行核算.结果建议进一步降低居民私人交通碳排放强度,提高居民能源消费的利用效率;同时鼓励发展小排量与新能源汽车消费,并且大力发展公共交通,倡导居民出行多采用公共交通工具出行,引导节能减排的出行方式.     

基于出行目的链的出行生成—分布组合模型分析

目前,我国城市轨道交通客流预测大多采用交通产生、吸引、出行分布、出行方式划分四阶段模型,其中出行生成与分布是方式划分和交通分配的前提,是模型重要的组成部分.在对传统的四阶段模型的分析基础上,结合非集计模型的优点,论文提出了基于出行目的链的出行生成—分布组合模型.模型充分考虑了居民出行链、出行目的等对客流预测的影响,在完善我国轨道交通客流预测理论和方法,提高预测精度等方面具有一定的理论价值和实际意义.     

双模式网络停车限制交通需求管理模型与方法研究

在轨道网和公路网并存的双模式交通网络, 合理设计出行终点的停车容量可优化汽车出行需求, 改善路网交通环境。本文通过分析私家车与城市轨道两种交通模式的出行需求, 并考虑私家车模式的终点停车收费服务, 建立了一种带路段环境容量和终点停车需求容量共同约束的交通需求管理模型。模型中路网使用者的出行模式采用二元Logit模型来计算, 而私家车的路线选择行为服从Logit随机用户均衡, 因此该模型是一个带不动点约束的数学规划问题。针对模型求解困难, 文中采用灵敏度分析来获取各路段流量和需求量关于终点容量波动的梯度信息, 进而设计了一种新的灵敏度分析求解算法.最后通过数值仿真实验, 验证了算法的有效性, 同时分析了不同停车收费参数对模型各指标变化趋势的影响。     

ETC对武汉交通畅通性的贡献率研究

城市交通畅通性是多因素综合作用的结果,受到城市规模、交通政策、出行结构及交通基础设施等多方面的影响.运用双重差分的核心思想,结合聚类分析,采用分位数回归,解决了内生性、控制组受影响的问题,从影响武汉交通畅通性的众多因素中,剥离出ETC系统的净贡献.     

城市非高峰期动态出行交通网络均衡

我国在城市化进程中,许多城市交通部门为了缓解城市交通拥堵问题,制订了大力发展公共交通的政策,而城市公共交通非高峰期的出行人群交通方式选择是一个值得讨论的问题.在此基础上通过分析几种不同的交通出行方式的分路段成本,建立了具有非高峰期特点的多方式出行路网模型,并对模型进行了计算求解,依据结果对非高峰期公共交通出行的特点进行了讨论.     

基于基尼系数的停车换乘拥挤收费定价模型

许多大城市提倡停车换乘的组合出行方式,目的是减少出行车辆,缓解交通拥挤状况.应用双层规划模型对停车换乘拥挤收费进行研究.下层模型采用弹性需求SUE模型,上层模型考虑了交通公平因素.以各出行方式占用的道路资源为公平指标,应用基尼系数对传统上层模型进行改造,构建一个用户盈余尽可能大而基尼系数尽可能小的上层模型,并利用基尼系数控制参数,实现在不同公平要求下的拥挤收费设计.算例表明,基于基尼系数的停车换乘拥挤收费设计,能改善道路的拥挤状况,且兼顾了用户盈余与公平.     

城市交通多类型随机用户出行决策模型研究

考虑城市交通中有多类出行者的一般情况,在ATIS等交通信息系统的影响下,不同类型的出行者对路径出行时间有不同理解,用不同的参数来反映.在此基础上,给出考虑路径选择、方式选择、讫点选择及是否出行的多类型随机用户出行决策模型,证明了模型的一阶条件满足路径选择、方式选择、讫点选择及是否出行的条件,最后给出模型算法.     

城市晚高峰地铁多方式出行均衡分析

随着我国城市化进程的加快,不仅一线城市地铁线路扩充至卫星城,一些二线大中型城市也将地铁建设纳入城市发展规划当中.地铁交通高峰出行具有准时及经济的特点,同时通勤人群选择地铁出行可有效地缓解地面交通拥堵.基于二线城市及一线城市卫星城的地铁交通线路未能完整覆盖从工作地到居住地的线路需要,本论文设计了城市晚高峰多方式出行均衡模型,研究晚高峰依托地铁多方式出行的交通特点并进行分析.对城市晚高峰人群可选择自行车地铁换乘、地铁出租车换乘等多方式达到晚高峰出行均衡,给出了参考性意见.     

收费机制下一类随机需求混合交通均衡分配的非合作代价

运用算法博弈论探讨一类随机需求混合交通均衡分配在收费机制下的非合作代价.首先,构建了收费机制下随机需求UE-CN混合交通均衡分配的变分不等式模型.其次,运用解析推导法分别得到单项式出行成本函数下是否将收费作为系统总成本一部分时,该类混合交通均衡分配的非合作代价上界表达式.在此基础上,探讨了出行需求服从对数正态分布时的非合作代价上界表达式.并以数值算例验证所得结论.     

The catwalk task: Reflections and synthesis: Part 2

In this article we recount our experiences with a series of encounters with the catwalk task and reflect on the professional growth that these opportunities afforded. First, we individually reflect on our own mathematical work on the catwalk task. Second, we reflect on our experiences working with a group of community college students on the catwalk task and our interpretations of their mathematical thinking. In so doing we also detail a number of innovative and novel student-generated representations of the catwalk photos. Finally, we each individually reflect on the entire experience with the catwalk problem, as mathematics learners, as teachers, and as professionals.     

A conjecture on bipartite graphical regular representations

In this paper we are concerned with the classification of the finite groups admitting a bipartite DRR and a bipartite GRR.First, we find a natural obstruction that prevents a finite group from admitting a bipartite GRR. Then we give a complete classification of the finite groups satisfying this natural obstruction and hence not admitting a bipartite GRR. Based on these results and on some extensive computer computations, we state a conjecture aiming to give a complete classification of the finite groups admitting a bipartite GRR.Next, we prove the existence of bipartite DRRs for most of the finite groups not admitting a bipartite GRR found in this paper. Actually, we prove a much stronger result: we give an asymptotic enumeration of the bipartite DRRs over these groups. Again, based on these results and on some extensive computer computations, we state a conjecture aiming to give a complete classification of the finite groups admitting a bipartite DRR.     

Fractional variational problems with the Riesz-Caputo derivative

In this paper we investigate optimality conditions for fractional variational problems, with a Lagrangian depending on the Riesz-Caputo derivative. First we prove a generalized Euler-Lagrange equation for the case when the interval of integration of the functional is different from the interval of the fractional derivative. Next we consider integral dynamic constraints on the problem, for several different cases. Finally, we determine optimality conditions for functionals depending not only on the admissible functions, but on time also, and we present a necessary condition for a pair function-time to be an optimal solution to the problem.     

Teachers’ beliefs towards teaching calculus

This paper focuses on the belief systems towards teaching calculus of 29 upper secondary mathematics teachers. Firstly, we discuss different educational trends in teaching calculus, and the theoretical approach based on the construct of belief systems. Afterwards we describe the method of our study used to analyse the belief systems of the calculus teachers. Referring to findings of our research, we firstly focus on central and peripheral beliefs and thus discuss the structure of the teachers’ belief systems. Further, we compare the teachers’ belief systems to established educational trends of teaching calculus. Finally, we conclude the paper by reflecting on our main findings and by discussing possible directions of further research.     

On the multiple values and uniqueness of algebroid functions on annuli

In this paper, we discuss the influence of multiple values and Valiron deficiencies on the uniqueness problem of algebroid functions on annuli, we get the several uniqueness theorems of algebroid functions on annuli, and also we extend the Nevanlinna value distribution theory for algebroid functions on annuli.     

Numerical computation of connecting orbits on a manifold

In this paper we propose a numerical method for approximating connecting orbits on a manifold and its bifurcation parameters. First we extend the standard nondegeneracy condition to the connecting orbits on a manifold. Then we construct a well-posed system such that the nondegenerate connecting orbit pair on a manifold is its regular solution. We use a difference method to discretize the ODE part in this well-posed system and we find that the numerical solutions still remain on the same manifold. We also set up a modified projection boundary condition to truncate connecting orbits on a manifold onto a finite interval. Then we prove the existence of truncated approximate connecting orbit pairs and derive error estimates. Finally, we carry out some numerical experiments to illustrate the theoretical estimates.     

机械臂运动路径设计

采用D-H方法推导出了机械臂角度姿态与指尖空间位置的关系,以距离偏差为目标,建立了给定位置求机械臂参数的优化模型,并提出了二分步长接近式搜索算法求解该模型.进一步从实际工程精度要求出发,提出了确定精度求指令的方法.针对按照确定曲线运行的问题,采取了离散曲线而且相邻离散点之间一条指令可达的方法,并用改进的二分步长接近式搜索算法来求解.提出了解决避障问题的启发式算法和位姿空间变换法.还对机械臂结构进行了理论分析及论证,根据分析结果,针对旋转角度范围、角度量化、杆长选择等方面提出了一些建议.     

Triple-point defective ruled surfaces

In [L. Chiantini, T. Markwig, Triple-point defective regular surfaces. arXiv:0705.3912, 2007] we studied triple-point defective very ample linear systems on regular surfaces, and we showed that they can only exist if the surface is ruled. In the present paper we show that we can drop the regularity assumption, and we classify the triple-point defective very ample linear systems on ruled surfaces.     

Positive one-parameter semigroups on ordered banach spaces

In this review we describe the basic structure of positive continuous one-parameter semigroups acting on ordered Banach spaces. The review is in two parts.First we discuss the general structure of ordered Banach spaces and their ordered duals. We examine normality and generation properties of the cones of positive elements with particular emphasis on monotone properties of the norm. The special cases of Banach lattices, order-unit spaces, and base-norm spaces, are also examined.Second we develop the theory of positive strongly continuous semigroups on ordered Banach spaces, and positive weak^*-continuous semigroups on the dual spaces. Initially we derive analogues of the Feller-Miyadera-Phillips and Hille-Yosida theorems on generation of positive semigroups. Subsequently we analyse strict positivity, irreducibility, and spectral properties, in parallel with the Perron-Frobenius theory of positive matrices.