Heuristic algorithms for a second-best congestion pricing problem

Designing a congestion pricing scheme involves a number of complex decisions. Focusing on the quantitative parts of a congestion pricing system with link tolls, the problem involves finding the number of toll links, the link toll locations and their corresponding toll level and schedule. In this paper, we develop and evaluate methods for finding the most efficient design for a congestion pricing scheme in a road network model with elastic demand. The design efficiency is measured by the net social surplus, which is computed as the difference between the social surplus and the collection costs (i.e. setup and operational costs) of the congestion pricing system. The problem of finding such a scheme is stated as a combinatorial bi-level optimization problem. At the upper level, we maximize the net social surplus and at the lower level we solve a user equilibrium problem with elastic demand, given the toll locations and toll levels, to simulate the user response. We modify a known heuristic procedure for finding the optimal locations and toll levels given a fixed number of tolls to locate, to find the optimal number of toll facilities as well. A new heuristic procedure, based on repeated solutions of a continuous approximation of the combinatorial problem is also presented. Numerical results for two small test networks are presented. Both methods perform satisfactorily on the two networks. Comparing the two methods, we find that the continuous approximation procedure is the one which shows the best results.     

Evolutionary game-theoretic model for dynamic congestion pricing in multi-class traffic networks

This paper describes an evolutionary game-theoretic learning model for dynamic congestion pricing in urban road networks, taking into account route choice stochasticity and reliability considerations, and the heterogeneity of users, in terms of their value of travel time and real-time information acquisition. The learning model represents the dynamic adjustments of users to travel cost changes which may take place in the day-to-day as well as the within-day timescales. The implementation into a simplified and a real urban road network signifies the important implications of modeling the dynamic and stochastic learning components of users’ behavior for accommodating the efficient deployment of congestion pricing schemes.     

Alternative marginal-cost pricing for road networks

In the literature, several studies have algebraically characterized the set of toll vectors or patterns that, when added to a user equilibrium problem, its solution would be system optimal. Toll vectors in this set are termed “valid.” While the toll vector commonly advocated in the literature, i.e., one that equates the toll on each link to its marginal external cost, is always valid, other valid toll vectors generally exist and many leave some utilized links in the network untolled. On the surface, this may appear unreasonable and seems to violate the principle of marginal-cost pricing. This note shows that, when travel demands are elastic, all valid toll vectors satisfy this principle, in that the total tolls for each path equals the congestion externality an additional traveler on the path imposes on others.     

Joint pricing and design of urban highways with spatial and user group heterogeneity

This paper addresses the joint optimization of capacity investments and toll charges imposed on multi-group users in monopolistic private highways within general road networks. A game-theoretic formulation is provided that leads to a nonconvex bilevel program. The proposed modeling framework handles several complex issues raised in realistic applications, such as regulations on the levels of tolls and service, and the discrete nature of highway capacity, using a genetic optimization technique. Real-application results show the importance of considering the spatial heterogeneity of prices, and the tradeoff between investments and pricing strategies in regulated private highways.     

Design and evaluation of road pricing: state-of-the-art and methodological advances

This article provides an in-depth review of the state-of-the-art and describes methodological advances in the design and evaluation of road network pricing schemes. A number of paradigm shifts from the two polar cases of the marginal social cost pricing of road traffic congestion and revenue-maximizing road toll pricing are analyzed, as induced by the need to address realistic design complexities and constraints. The crucial role of the joint consideration of pricing strategies with optimal capacity provision and several network management measures is manifested and an integrated evaluation framework is suggested to incorporate a wide range of road pricing impacts into the scheme design process.     

异构无线系统中一种改进的呼叫准入方案

针对异构无线系统中上、下行业务需求不平衡引起的拥塞现象,提出了一种改进的呼 叫准入方案。首先给出接入倾向度的概念,在接入时考虑用户的实际接入需求,并进一步提 出了基于接入倾向度的呼叫准入改进方案,最后利用无差别曲线的方法确定接入倾向度的选 择。仿真结果表明,改进后的方案在系统性能与用户公平性之间做到了较好折衷,具有较 大的实用价值。     

Dynamic Benchmarking of Mass Transit Systems in the United States Using Data Envelopment Analysis and the Malmquist Productivity Index

For more than five decades, the federal, state, and local governments have subsidized mass transit systems through sales, gasoline, and property taxes with an expectation that it would improve mobility to low‐income citizens, reduce carbon footprints and traffic congestion, and facilitate regional economic growth. However, in times of financial crisis and chronic government budget deficits, the inefficient use of a mass transit system can increase public outcry over the wasteful spending of government funds and taxpayers’ monies. To find ways to utilize mass transit systems more efficiently across the United States, this paper aimed to identify the benchmark transit practices that every mass transit system can emulate and then continuously improve its performance. To achieve these goals, this paper analyzed the multiple years of past performances of 262 mass transit agencies in the United States using data envelopment analysis and the Malmquist productivity index and then provided practical guidelines for enhancing mass transit efficiency.     

基于列生成的毫米波多连接链路配置调度算法

多连接技术允许用户同时建立和保持与多个小区/接入点的连接，通过网络元素之间的协调在吞吐量和可靠性方面大幅提高网络性能。针对毫米波通信中超高频段的链路中断问题，研究了多连接基于链路配置的调度算法，以提高链路调度效率，降低复杂度。首先，在系统模型中采用链路配置作为优化变量；其次，设计了多连接比例公平的调度准则；最后，提出一种基于列生成算法的链路配置调度优化算法，利用Dantzig-Wolfe分解将原问题分解为限制主问题和定价问题，并结合分支定界方法获得最优解。仿真结果表明，所提算法能够在数值上逼近全局最优，并且比现有的毫米波蜂窝网络链路调度方案增益平均提高40%以上。     

基于可靠性的城市公交乘客满意度评价模型

本文提出了一种高峰小时下公交乘客满意度的评价模型。模型通过层次分析法得出行程时间可靠性、容量可靠性、站点准点到达可靠性三个可靠性指标,乘车环境舒适性、驾驶员驾驶技术、车内拥挤度三个舒适性指标,以及票价合理性这个经济性指标。评价指标量化值由层次分析—模糊综合判定方法获得。最后,利用深圳市和北京市的两条典型公交线路对模型进行了案例分析。     

The Progressive Second Price Mechanism in a Stochastic Environment

We consider in this paper an auction-based pricing scheme recently introduced by Lazar and Semret to allocate bandwidth among users. This mechanism, called Progressive Second Price, was studied using tools from noncooperative game theory, for a fixed set of players (i.e., users). We compare here the results obtained in that case with the more realistic situation when players randomly enter or leave the game. We assume that they enter according to a Poisson process, and leave it after an exponentially distributed sojourn time. We show that this stochastic assumption cannot be skipped since it can lead to very different results.     

城市交通拥堵问题的经济学解析

城市交通拥堵的形成是由以私人汽车为代表的民用车辆对交通量的巨大需求与供应不足的城市道路之间的矛盾引起的。解决交通拥堵问题,降低人们的出行成本,必须建设和完善合理的公共交通体系,分流掉私人汽车对交通量的巨大需求;必须加大道路基础设施建设,增加交通量的供给;在政府与市场两个方面的作用下,实现供给与需求的新的均衡,从而增加社会福利,实现帕累托最优。     

Awareness of Distributed Denial of Service Attacks' Dangers: Role of Internet Pricing Mechanisms

Denial of Service (DoS) attacks consist of overwhelming a server, a network or a Web site in order to paralyze its normal activity. The additional parameter in Distributed Denial of Service (DdoS) attacks is the distributing strategy. It means that DDoS attacks do not come from a single computer but stem from all accessible channels and servers. Consequences are multiple, ranging from system errors, temporary inability to access the Web site for normal users to challenging the actual reliability of the Internet. Despite this, Internet users show carelessness. The explanation lies in the specificities of DDoS attacks. We explore possibilities to raise users' awareness about the actual amplitude of problems caused by DDoS attacks. We suggest a careful examination of Internet pricing mechanisms and switching from flat to usage-constraining pricing schemes.     

Short-term or long-term cooperation between retailer and MCN? New launched products sales strategies in live streaming e-commerce

Nowadays, live streaming e-commerce has become popular all over the world. In this paper, we study the pricing strategy of new products when they are launched in live streaming considering the consumer uncertainty and network externalities. We characterize the impact of live streaming into two dimensions, emotional support and information support, and investigate how those two dimensions impact the choice of cooperation types and the revenue distribution between the retailer and MCN (Multi-Channel Network). Using a two-stage vertical model, we find that, with the low consumer uncertainty, the MCN induces the retailer to choose the cooperation type depending on the emotional support level, but with the high consumer uncertainty, it depends on the information support level. For new-product pricing strategy, whether to adopt the penetration pricing strategy or the skimming pricing strategy depends on the impact of live streaming, the consumer uncertainty and network externalities. Interestingly, the commission price does not increase with the consumer uncertainty. An important implication for the retailer is that, reducing consumer uncertainty may not be beneficial to the total profit.     

Ensuring trust in one time exchanges: solving the QoS problem

We describe a pricing structure for the provision of IT services that ensures trust without requiring repeated interactions between service providers and users. It does so by offering a pricing structure that elicits truthful reporting of QoS by providers while making them profitable. This mechanism also induces truth-telling on the part of users reserving the service.     

试论浙江在徐霞客旅行中的重要价值

本文基于徐霞客八次踏入浙江的旅行经历,分析浙江在徐霞客旅行中具有重要价值,指出浙江是徐霞客旅行的重要中转基地,是徐霞客真正进行科学考察的开始之地,是徐霞客西南数万里远游的发轫之地,是徐霞客进行远游准备的实验基地。同时,浙江籍友人也为徐霞客旅行做出了不可替代的重要贡献。     

基于行程时间可靠性改进的公交服务水平优化策略

在公共交通顾客满意度评价体系中,行程时间可靠性具有极其重要的作用。基于此,本文提出了通过改进行程时间可靠性以提高公交服务水平的策略。在可靠性改进模型中,以专用车道设置费用最小为目标函数,行程时间可靠性为机会约束,建立了机会约束规划模型,并在求解时将其转化为整数规划,利用分支定界算法和遗传算法进行求解。在文章的最后,以新加坡188路公交车为例进行了案例分析。     

移动自组织网络中基于QoE的跨层多波束信道接入机制

引入数字多波束技术可以使移动自组织网络的信道容量得到有效提升，然而，时间、频率、空间、用户、功率等多维度资源域的统一调度与跨层联合优化使得信道接入机制的分析与设计变得更加复杂。为此，结合多波束的特性，将波束宽度限制、收发限制、通道限制、功率限制等多种约束条件抽象图论问题，并建立分析模型。基于分析模型，进一步提出了MB-MAC（Multi-beam Medium Access Control）信道接入机制，结合物理层的预编码技术，建立定向链路的队列模型，度量用户的满意度(Quality of Experience,QoE)，设计了适用于自组织网络中多用户并发并收的信道接入机制，兼顾了网络容量和用户满意度。仿真结果表明，MB-MAC机制能在保证各个用户满意度的情况下，有效提升网络吞吐率。     

An Argument Against Abridging Consumer Right of Bankruptcy

As our economy now operates, consumer credit is an essential ingredient in the mass merchandising of goods and services, credit sources and users share a joint responsibility in orginating credit and both share in its beneficial effects. Thsoe had debt losses which occur are small relative to sales and are absorbed by consumers who pay in full. In this mileu, abridging the right of bankruptcy would provide negligible benefits to consumers as a whole and to the economy. It would create serious inequity between (1) consumers who avoid debt through procrastination and those who avoid it through bankruptcy and (2) consumers and business firms. The first inequity would be accentuated by present differences in state laws governing debt collection. It would still exist, however, if all states had a uniform collection law. Consumer right to bankruptcy is a needed safety-value in our credit-oriented economy.     

Price dispersion of online air tickets for short distance international routes

The travel industry is currently experiencing a major transition as distribution channels change in response to developments in information technology. This study investigated whether online travel agents (OTAs) can offer air tickets with different prices given the lower search costs made possible by the Internet. This investigation first examined the hypothesis that price dispersion does not exist in air ticket offerings by OTAs. Hedonic regression models with log-linear form are then built to explain the pricing characteristics of air tickets. After accounting for differences in ticket attributes, ticket prices were found to vary by as much as 1.859% across OTAs. In other words, different OTAs were offering identical tickets at different prices. Statistically, significant interaction effects existed between airlines and OTAs, suggesting that travelers with specific airline preferences should expect to find different prices on different OTAs, even when ticket attributes are identical. This work thus revealed imperfections in the online air ticket market. It is therefore necessary for fare conscious air travelers to search different web services provided by OTAs to locate the best deal.     

微波通信应急组网仿真系统设计

针对通信保障方案生成方式及评估手段落后的问题,设计了微波通信应急组网仿真系 统。系统以模块化的形式设计了体系结构,采用层次分析法构建了通信装备建模框架,通过 流程图描述了仿真过程并提出仿真实现方法,实现了数据库管理,给出了通信效果评估依据 及评估实现方法。最后通过日常组网训练仿真验证了系统的可行性与可靠性。系统通过虚拟 评估手段为用户提供较精确的数据支撑和结果分析,可对通信保障方案生成起辅助决策作用 ,有效提高应急通信保障效率。