Modeling traffic operations at electronic toll collection and traffic management systems

Automatic Vehicle Identification (AVI) technology is one possible solution to traffic congestion at existing transportation facilities. This paper presents a mathematical model of traffic conditions for toll plaza facilities that includes AVI toll collection services among other conventional services.

Three types of services are available: manual toll service, in which transactions are handled by a toll collector, automatic toll service, in which coin machines are utilized, and AVI toll collection service. In addition, mixed lanes, which provide more than one of the above services, are considered by the model.

For a given rush hour, queue lengths and delays can be calculated for different toll plaza configurations. Comparison of their performance may aid operators in the management of the lane configurations until all users of the facility become AVI patrons.     

An overview of the Yale Gem system

The Gem system is an experimental computing facility that provides low cost, high speed, graphics-oriented computing to between ten and sixteen simultaneous users. It provides many unusual facilities to its users and presents a user interface that is unique in its convenience and flexibility. The motivation for the system, its design and user experience are described. Possible future avenues of research are also outlined.     

高性能计算机用户信息的统一管理

高性能计算是气象业务及科研应用的重要的基础平台,中国气象局 (China Meteorological Administration,CMA) 近年来相继引进多套高性能计算机系统,随着气象业务和应用能力的不断提高,系统利用率稳步上升,用户数也逐月增加,截止到 2012 年底,用户总数超过 600 人。用户数的增加、用户的变动导致系统中的用户信息不完整、错误以及无法更新,以至出现问题时无法及时联系到相关用户,对系统的维护管理及用户支持造成了一定的困难。本文介绍了对 CMA 多套高性能计算机系统上的用户信息进行统一管理的设计思路和具体实现,相关工作的完成有助于减少管理和维护成本,更好的为用户提供优质的支持和服务。     

Application Briefs

Continental Graphics opened a new facility last March in central Los Angeles to provide computer-aided design and drafting services to the area's architects and engineers. " The system gives architects and engineers the freedom to practice their profession rather than being involved in repetitious work which a computer can perform in minutes," Curtis F. Bourland, president, pointed out at an open house attended by potential users. The company plans similar facilities in Denver, Houston, San Francisco, and Orange County (California).     

Providing Reference in a Joint-Use Library

SUMMARY

As a one of a kind joint-use facility between a private university and a county government, the Alvin Sherman Library, Research, and Information Technology Center at Nova Southeastern University (NSU) provides reference services to both NSU students on and off campus and public users. Reference librarians have had to adjust to the variety of users and demands for new services and at the same time find new and creative methods of offering, promoting, and providing instruction about their services to public users as well as NSU's local and distance students. Tracking statistics can assist in identifying user needs.     

Implementing an open link service for the World Wide Web

Links are the key element for changing a text into a hypertext, and yet the WWW provides limited linking facilities. Modeled on Open Hypermedia research the Distributed Link Service provides an independent system of link services for the World Wide Web and allows authors to create configurable navigation pathways for collections of WWW resources. This is achieved by adding links to documents as they are delivered from a WWW server, and by allowing the users to choose the sets of links that they will see according to their interests. This paper describes the development of the link service, the facilities that it adds for users of the WWW and its specific use in an Electronic Libraries project.     

Solution approaches for facility location of medical supplies for large-scale emergencies

In this paper, we propose models and solution approaches for determining the facility locations of medical supplies in response to large-scale emergencies. We address the demand uncertainty and medical supply insufficiency by providing each demand point with services from a multiple quantity of facilities that are located at different quality levels (distances). The problem is formulated as a maximal covering problem with multiple facility quantity-of-coverage and quality-of-coverage requirements. Three heuristics are developed to solve the location problem: a genetic algorithm heuristic, a locate–allocate heuristic, and a Lagrangean relaxation heuristic. We evaluate the performance of the model and the heuristics by using illustrative emergency examples. We show that the model provides an effective method to address uncertainties with little added cost in demand point coverage. We also show that the heuristics are able to generate good facility location solutions in an efficient manner. Moreover, we give suggestions on how to select the most appropriate heuristic to solve different location problem instances.     

Super facilities versus chaining in mitigating disruptions impacts

Dealing disruptions has increasingly attracted researchers’ attention in the last decades due to recent events: weather deregulation, natural disasters, financial crisis, etc. Researchers often dealt with the strategic aspect of the problem while making facility location decisions to build a robust supply chain. In this paper we address the flexibility aspect. We consider the problem of allocating demand arising from a set of products to a set of dedicated facilities. The facilities are subject to disruption and the demand is then lost. To mitigate disruption impacts, we consider the use of a super facility that can hold the demand of products when the dedicated facilities are under failure. In systems with identical products and facilities, we propose an algorithm that can be used to determine the optimal capacity of the super facility so as to minimize the sum of capacity investment, demand allocation and lost sales cost. Finally we compare the performance of the super facility configuration to that of the single chain configuration. The single chain refers to a facility configuration where each facility is configured to fulfill only two products and each product can be assigned to only two facilities and the whole system forms a closed chain.     

Resource management policies in GPRS systems

In this paper we consider the problem of resource management in GSM/GPRS cellular networks offering not only mobile telephony services, but also data services for the wireless access to the Internet. In particular, we investigate channel allocation policies that can provide a good tradeoff between the QoS guaranteed to voice and data services end users, considering three different alternatives, and developing analytical techniques for the assessment of their relative merits. The first channel allocation policy, voice priority, gives priority to voice in the access to radio channels; we show that this policy cannot provide acceptable performance to data services, since when all the channels are busy with voice connections, data services perceive long intervals of service interruption. The second channel allocation policy is called R-reservation; it statically reserves a fixed number of channels to data services, thus drastically improving their performance, but subtracting resources from voice users, even when these are not needed for data, thus inducing an unnecessary performance degradation for voice services. The third channel allocation policy is called dynamic reservation; as the name implies, it dynamically allocates channels to data when necessary, using the information about the queue length of GPRS data units within the base station. A threshold on the queue length is used in order to decide when channels must be allocated to data. Numerical results show that the dynamic reservation channel allocation policy can provide effective performance tradeoffs for data and voice services, with the additional advantage of being easily managed through the setting of the threshold value.     

An object-oriented multimedia database system for a news-on-demand application

We describe the design of a multimedia database management system for a distributed news-on-demand multimedia information system. News-on-demand is an application that uses broadband network services to deliver news articles to subscribers in the form of multimedia documents. Different news providers insert articles into the database, which are then accessed by users remotely, over a broadband, asynchronous transfer-mode (ATM) network. The particulars of our design are an object-oriented approach and strict adherence to international standards, in particular the Standard Generalized Mark-up Language (SGML) and Hy-Time. The multimedia database system has a visual query facility, which is also described in this paper. The visual query interface provides three major facilities for end users: presentation, navigation, and querying of multimedia news documents. The main focus, however, is the querying of multimedia objects stored in the database.     

Maximizing Expected Coverage of Flow and Opportunity for Diversion in Networked Systems

Placement of facilities, such as those providing surveillance or assistance functions, is essential for effective and efficient system operation. Planning for where to provide these types of services in a network necessitates addressing different objectives. For instance, notifying users of future network conditions and/or availability of other services requires general exposure to that information at some point during a movement between an origin and destination. Alternatively, the usefulness of services such as the provision of information regarding current network conditions can depend upon where the service is provided relative to opportunities for users to divert from their current path to make use of that service. Regardless of the service to be made available, there is always some uncertainty as to whether or not it will be available and/or observed by users of the system. To address these planning considerations, several new models for optimizing the location of service facilities in a network are described. In particular, the proposed models account for expected coverage of network flows as well as the opportunity that exists for flows to make effective use of a service once it has been provided. While the proposed models involve non-linear objective functions, it is shown that a linearization exists given the topological relationships within a network. The developed optimization models are then integrated into a multi-objective modeling framework and applied to a case study to demonstrate the tradeoffs that exist between the planning objectives.

     

The gravity multiple server location problem

Models for locating facilities and service providers to serve a set of demand points are proposed. The number of facilities is unknown, however, there is a given number of servers to be distributed among the facilities. Each facility acts as an M/M/k queuing system. The objective function is the minimization of the combined travel time and the waiting time at the facility for all customers. The distribution of demand among the facilities is governed by the gravity rule. Two models are proposed: a stationary one and an interactive one. In the stationary model it is assumed that customers do not consider the waiting time at the facility in their facility selection decision. In the interactive model we assume that customers know the expected waiting time at the facility and consider it in their facility selection decision. The interactive model is more complicated because the allocation of the demand among the facilities depends on the demand itself. The models are analyzed and three heuristic solution algorithms are proposed. The algorithms were tested on a set of problems with up to 1000 demand points and 20 servers.     

System lifecycle processes for cyber security in a research reactor facility

The digitalization of nuclear facilities has brought many benefits,including high performance and convenient maintainability,in terms of facility operation.However,cyber accidents accompanied by the use of digital technologies have increased,and cyber security has been one of the most important issues in the nuclear industry area.Several guidelines have been published for nuclear power plants,but it is difficult to apply all requirements within the guidelines to research reactor facilities because the characteristics in terms of facility scale,purpose,and system design,are different from those of power plants.To address this emerging topic,this paper introduces system lifecycle processes for cyber security in a research reactor facility.It addresses the integration of activities for securing systems and guarding a facility safely using the practices at a research reactor facility.     

Correlations between characteristics of maximum influence and degree distributions in software networks

Software systems can be represented as complex networks and their artificial nature can be investigated with approaches developed in network analysis.Influence maximization has been successfully applied on software networks to identify the important nodes that have the maximum influence on the other parts.However,research is open to study the effects of network fabric on the influence behavior of the highly influential nodes.In this paper,we construct class dependence graph(CDG)networks based on eight practical Java software systems,and apply the procedure of influence maximization to study empirically the correlations between the characteristics of maximum influence and the degree distributions in the software networks.We demonstrate that the artificial nature of CDG networks is reflected partly from the scale free behavior:the in-degree distribution follows power law,and the out-degree distribution is lognormal.For the influence behavior,the expected influence spread of the maximum influence set identified by the greedy method correlates significantly with the degree distributions.In addition,the identified influence set contains influential classes that are complex in both the number of methods and the lines of code(LOC).For the applications in software engineering,the results provide possibilities of new approaches in designing optimization procedures of software systems.     

When changing the look of privacy policies affects user trust: An experimental study

The majority of Internet users do not read privacy policies because of their lengthy verbose format, although they are still the main source of information for users about how their data are collected and used. Consequently, as shown by many studies, users do not trust online services with respect to the use of their private data. Furthermore, they find it unfair that their data are used to generate revenue by online services without their knowledge or without their benefit from this.In this paper, we take as main assumption that the control of their private data and also caring about their interests would restore the trust of users. Based on an empirical model, we conducted an experimental comparative study of user trust by offering to two groups of participants the possibility to adhere to a service with a privacy policy presented in one of two different formats: the first, a conventional privacy policy and the second, designed according to the privacy policy model studied in this paper.We collected, through a survey, 717 responses from participants. The results show that allowing personalization and management in privacy policies affects user trust and makes online services appear more trustworthy to their users.     

Variable neighborhood search for the p-median

Consider a set L of potential locations for p facilities and a set U of locations of given users. The p-median problem is to locate simultaneously the p facilities at locations of L in order to minimize the total transportation cost for satisfying the demand of the users, each supplied from its closest facility. This model is a basic one in location theory and can also be interpreted in terms of cluster analysis where locations of users are then replaced by points in a given space. We propose several new Variable Neighborhood Search heuristics for the p-median problem and compare them with Greedy plus Interchange, and two Tabu Search heuristics.     

Using distributed objects for digital library interoperability

Information repositories are just one of many services tomorrow's digital libraries might offer. Other services include automated news summarization, trend analysis across news repositories, and copyright-related facilities. This distributed collection of services has the potential to be enormously helpful in performing information-intensive tasks. It could also turn such tasks into confusing, frustrating annoyances by forcing programmers and users to learn many interfaces and by confronting users with the bewildering details of fee-based services that were previously only accessible to professional librarians. The Stanford Digital Library project is addressing the problem of interoperability, which is particularly important because standardization efforts are lagging behind the development of digital library services. The authors used CORBA to implement information-access and payment protocols. These protocols provide the interface uniformity necessary for interoperability, while leaving implementers a large amount of leeway to optimize performance and to provide choices in service performance profiles. The authors' initial experience indicates that a distributed object framework does give clients and servers the flexibility to manage their communication and processing resources effectively     

A bilevel fixed charge location model for facilities under imminent attack

We investigate a bilevel fixed charge facility location problem for a system planner (the defender) who has to provide public service to customers. The defender cannot dictate customer-facility assignments since the customers pick their facility of choice according to its proximity. Thus, each facility must have sufficient capacity installed to accommodate all customers for whom it is the closest one. Facilities can be opened either in the protected or unprotected mode. Protection immunizes against an attacker who is capable of destroying at most r unprotected facilities in the worst-case scenario. Partial protection or interdiction is not possible. The defender selects facility sites from m candidate locations which have different costs. The attacker is assumed to know the unprotected facilities with certainty. He makes his interdiction plan so as to maximize the total post-attack cost incurred by the defender. If a facility has been interdicted, its customers are reallocated to the closest available facilities making capacity expansion necessary. The problem is formulated as a static Stackelberg game between the defender (leader) and the attacker (follower). Two solution methods are proposed. The first is a tabu search heuristic where a hash function calculates and records the hash values of all visited solutions for the purpose of avoiding cycling. The second is a sequential method in which the location and protection decisions are separated. Both methods are tested on 60 randomly generated instances in which m ranges from 10 to 30, and r varies between 1 and 3. The solutions are further validated by means of an exhaustive search algorithm. Test results show that the defender's facility opening plan is sensitive to the protection and distance costs.     

Optimal facility location with random throughput costs

In this paper we consider the optimal location and size of facilities where the throughput costs for each facility are random. Given a set of origins and a set of destinations, we want to determine the optimal location and size of a set of intermediate facilities in order to minimize the expected total generalized transportation cost. The generalized transportation cost of a freight unit from an origin to a destination passing through a facility is the sum of two terms: the transportation cost from the origin to the destination through the facility and the throughput cost of the facility. While the first term is deterministic, the second one is stochastic with a Gumbel probability distribution. Looking for the expected value of the optimal solution, a mixed deterministic nonlinear problem for the optimal location of the facilities is derived. Two heuristics, which give very good approximations to the optimum, are proposed.     

Efficient location and allocation strategies for undesirable facilities considering their fundamental properties

The phrase “not in my backyard” (NIMBY) refers to the well-known social phenomena in which residents oppose the construction or location of undesirable facilities near their homes. Examples of such facilities include electric transmission lines, recycling centers and crematoria. Due to the opposition typically encountered in constructing an undesirable facility, the facility planner should understand the nature of the NIMBY phenomena and consider it as a key factor in determining facility location. We examine the characteristics of NIMBY phenomena and suggest two alternative mathematical optimization models with the objective of minimizing the total degree of NIMBY sentiments. Genetic algorithms are proposed to solve our linear and nonlinear integer programs. The results obtained via genetic algorithms for our linear integer programs are compared with those of CPLEX to evaluate their performance. The nonlinear programs are tested with various allocation policies. Sensitivity analysis is conducted about several system parameters.