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This article examines a web site designed to help computer users who are in the market of purchasing a computer cluster network determine what product they need. The article discusses how people normally approach purchasing a cluster system, noting they are normally constrained by a price or pay too much for something that does much more than they need. The web site they discuss is called the Cluster Design Rules and the objective of the site is to match the right application to the right user.

The article focuses on the design of AnySpot, a Web-service-based platform for mobile computing. Users can connect to their personal or shared documents because AnySpot's platform features personalized access, seamless sharing, portable and embedded interfaces, and integrated network services. The AnySpot architecture can be implemented without adding new storage systems, operating systems, or client interfaces. The platform combines in-place and remote-access solutions that support AnySpot's shared proxies and shared copies file systems. INSET: Tools for Mobile Document Access and Sharing.

A basic question in virtual private network (VPN) design is if the symmetric version of the problem always has an optimal solution which is a tree network. An affirmative answer would imply that the symmetric VPN problem is solvable in polynomial time. We give an affirmative answer in case the communication network, within which the VPN must be created, is a circuit. This seems to be an important step towards answering the general question. The proof relies on a dual pair of linear programs and actually implies an even stronger property of VPNs. We show that this property also holds for some other special cases of the problem, in particular when the network is a tree of rings. [ABSTRACT FROM AUTHOR]

Most call admission control (CAC) schemes proposed for dynamic channel allocation (DCA)-based systems simply follow the same philosophy as adopted by fixed channel allocation (FCA)-based systems, i.e., only considering intercell handoffs. Doing so is acceptable for FCA and coordinated DCA systems because an intracell handoff caused by a new channel assignment rarely happens in these cases. However, as discussed in this paper, in a distributed DCA with a measurement-based channel assignment, the intracell handoff may happen frequently and can dominate handoff events because failed intracell handoffs reduce the number of intercell handoffs. In this case, the CAC considering only the intercell handoff cannot work properly for such DCA systems. In this paper, we discuss a novel CAC to consider both intercell and intracell handoffs to guarantee a handoff call dropping probability (CDP) by jointly using the channel carrying approach. We also investigate a measurement-based implementation of this proposal through computer simulations. The results show that the proposed CAC can effectively bound the CDP to a target CDP. [ABSTRACT FROM AUTHOR]

Flooding is a commonly used technique for network resource and topology information dissemination in the data communication networks. However, due to the well-known N-squared problem it causes network delay in response or even congestion. We propose a new flooding technique, called Lazy Flooding; it floods only when links reach a certain status. It significantly cuts down the number of floods and thus improves the data communication network response time. On the other hand, it has negligible effect on the network performance due to the selected flooding. [ABSTRACT FROM AUTHOR]

The article presents the third series on Web application development discussion, the post-Enterprise Java Beans Java 2 Enterprise Edition Web application architecture. The architecture is given added support for automated component, acceptance testing, and integration. The aim is to achieve confidence in the accuracy of application-specific components, their integration with one another, and integration with components from different frameworks.

In Part I of this paper, the optimal throughput-delay tradeoff for static wireless networks was shown to be D(n) = ϴ(nT(n)), where D(n) and T(n) are the average packet delay and throughput in a network of, nodes, respectively. While this tradeoff captures the essential network dynamics, packets need to scale down with the network size. In this ‘fluid model,’ no buffers are required. Due to this packet scaling, D(n) does not correspond to the average delay per bit. This leads to the question whether the tradeoff remains the same when the packet size is kept constant, which necessitates packet scheduling in the network. In this correspondence, this question is answered in the affirmative by showing that the optimal throughput-delay tradeoff is still D(n) = ϴ(nT(n)), where now D(n) is the average delay per bit. Packets of constant size necessitate the use of buffers in the network, which in turn requires scheduling packet transmissions in a discrete-time queuing network and analyzing the corresponding delay. Our method consists of deriving packet schedules in the discrete-time network by devising a corresponding continuous-time network and then analyzing the delay induced in the actual discrete network using results from queuing theory for continuous-time networks. [ABSTRACT FROM AUTHOR]

In a previous paper, Gouveia and Magnanti (2003) found diameter-constrained minimal spanning and Steiner tree problems to be more difficult to solve when the tree diameter D is odd. In this paper, we provide an alternate modeling approach that views problems with odd diameters as the superposition of two problems with even diameters. We show how to tighten the resulting formulation to develop a model with a stronger linear programming relaxation. The linear programming gaps for the tightened model are very small, typically less than 0.5–, and are usually one third to one tenth of the gaps of the best previous model described in Gouveia and Magnanti (2003). Moreover, the new model permits us to solve large Euclidean problem instances that are not solvable by prior approaches. [ABSTRACT FROM AUTHOR]

We present empirical results on computing optimal dominating sets in networks by means of data reduction through efficient preprocessing rules. Thus, we demonstrate the usefulness of so far only theoretically considered data reduction techniques for practically solving one of the most important network problems in combinatorial optimization. [ABSTRACT FROM AUTHOR]

In recent years we have evidenced an extensive effort in the development of computer communication networks, which have deeply integrated in human being's everyday life. One of the important aspects of the network design process is the topological design problem involved in establishing a communication network. However, with the increase of the problem scale, the conventional techniques are facing the challenge to effectively and efficiently solve those complicated network design problems. In this article, we give a brief survey on our recent research works of network design problems by using genetic algorithms (GAs), such as, multistage process planning problem, fixed charge transportation problem, minimum spanning tree problem, centralized network design, and local area network design, shortest path problem, minimum cost maximum flow problem, and optimal scheduling problems based on network topology. All these problems are illustrated from the point of genetic representation encoding skill and the genetic operators with hybrid strategies. Numerical experiments show the effectiveness and efficiency of such kind of GA-based approach. [ABSTRACT FROM AUTHOR]

Focuses on the use of public key infrastructure (PKI). History of PKI; Recommendations for (PKI) design; Application of PKI. INSET: PKI Design Recommendations..

We have worked with the local access network design problem with two cable technologies. This is an optimization problem in graphs that consists of linking an origin node to a set of terminal nodes which have a flow demand. There are also a set of Steiner or transshipment nodes which do not have demand. Each arc of the graph has two associated costs: a variable cost depending on the flow through the arc and a fixed cost associated with the installation of the arc. Moreover, in each arc we can install one of two available technologies: optical fiber or copper (we can also use radio links with any other cable technology). Each one of these technologies has different variable and fixed costs. To be more precise, the fixed cost of the optical fiber is greater than that of the copper, but its variable cost is much smaller. The problem was modeled using a multicommodity flow formulation in which we added some structural constraints. This model was used to apply the Benders decomposition method. The structural constraints have the objective of trying to guarantee that the master problem of the Benders decomposition will yield a tree. The Benders subproblems are trivial network flow problems. The dual variables have commodity meaningful values and are evaluated in a systematic form. The algorithm was implemented in C++ with CPLEX 5.0 callable library. We have tested the algorithm with some test instances obtained by a generator of problems that we developed. [ABSTRACT FROM AUTHOR]

The article focuses on the importance of computer network architect in the building and designing networks. Topics discussed include a bachelor's degree in a computer-related field is a requirement for employment of a computer network architect, the pay and benefits for a computer network architect, and the job outlook for computer network architects. An interview with director Stephan Jones of the Center for Information and Communication Sciences (CICS) at Ball State University is presented.

Presents a goal programming methodology for solving maintenance scheduling (MS) of thermal generating units under economic and reliability criteria. Review of different techniques for solving the MS problem; Description of the proposed model; System modeling description; Implementation of the proposed model.

It is intended to state clearly the strategy of introducing optical networks into access networks. A tool for evaluating the initial cost and the maintenance operation cost of the networks is investigated. The evaluation procedure and the software structure for that purpose are reported. This paper is the first, as far as the authors know, to report on a tool that can evaluate costs up to the maintenance cost. When the network area, the transmission equipment, and the network configuration are given as input, the facilities, the installation work, the maintenance work, as well as their costs can be calculated using the proposed tool. The program is composed of modules, which facilitates corrections such as addition and modification. The initial cost and maintenance cost figures for a network derived by the proposed tool are analyzed considering the character of the network. It is seen that the structure of the cost is adequate. In other words, the tool can quantitatively analyze the economic aspect of the network, with an adequate calculation procedure and program structure. In investment planning, both the initial cost needed at installation and the maintenance cost needed every year must be considered. Using the proposed tool, the basic figures for those costs can be derived. In other words, the proposed tool can provide a basis for planning the detailed introduction of an optical network. © 1999 Scripta Technica, Electron Comm Jpn Pt 2, 82(9): 53–67, 1999 [ABSTRACT FROM AUTHOR]

Distributed group support systems are likely to be widely used in the future as a means for dispersed groups of people to work together through computer networks. They combine the characteristics of computer-mediated communication systems with the specialized tools and processes developed in the context of group decision support systems, to provide communications, a group memory, and tools and structures to coordinate the group process and analyze data. These tools and structures can take a wide variety of forms in order to best support computer-mediated interaction for different types of tasks and groups. This article summarizes five case studies of different distributed group support systems developed by the authors and their colleagues over the last decade to support different types of tasks and to accommodate fairly large numbers of participants (tens to hundreds). The case studies are placed within conceptual frameworks that aid in classifying and comparing such systems. The results of the case studies demonstrate that design requirements and the associated research issues for group support systems can be very different in the distributed environment as compared to the decision room approach. [ABSTRACT FROM AUTHOR]

The growth of end-user computing and the trend toward the use of packaged software have focused greater attention on issues related to user support. A varied user population is requiring more tailored support, yet vendor-supplied software with a generic interface is increasingly being used. Four case studies illustrate ways in which organizational forms of support can enhance or overcome the limitations of the software interface. A framework called the organizational interface incorporates these organizational mechanisms by integrating the computer-human interaction (CHI), management information systems (MIS), and end-user computing (EUC) approaches to user support. This framework can be used in the design of end-user systems developed with packaged software and for retrofitting outdated user interfaces for an end-user computing environment. The organizational interface provides IS and end-user managers with a means to consider alternative methods of providing support for systems based on purchased software with fixed user interfaces. [ABSTRACT FROM AUTHOR]

This article addresses how information systems architecture can be used to support organizations in the 1990s—organizations that face the dual challenge of "speed and flexibility" and "low cost and efficiency." At the heart of this challenge is the basic notion that information systems have been anything but flexible in the past and that, for many firms, information systems are more disablers of flexibility than enablers. The article discusses two architectural solutions to this problem: "the high road and the low road," and the benefits and pitfalls of each. We conclude that neither solution will succeed on its own and that firms need to combine elements of both to meet the challenges of the 1990s. This article is based on some of the things we have learned through research, case writing, and consulting while working with a variety of organizations over the past three years. These experiences have illustrated the importance of and the struggle with IS architecture for today's global competitors. The content is intended to help guide, provoke, stimulate, and entertain others who believe that the integration of information technology with organizational strategy and structure is of paramount concern to senior managers. [ABSTRACT FROM AUTHOR]

This paper studies the problem of computing the source-to-terminal reliability, the probability that a source s can communicate with a terminal t, in a probabilistic directed network. It introduces a set of reliability-preserving reductions, called 2-neighbor-node reductions. We show that for a class of directed networks, called BSP-digraphs, such reductions are always admissible and the source-to-terminal reliability can be computed in time linear in the size of the network. A directed network D = (V, E) is a BSP-digraph if its underlying undirected graph is series-parallel. The BSP-digraphs considered cen be cyclic or acyclic and both vertices as well as edges can fail. Any two vertices can be chosen as s and t. Previously, no polynomial time algorithms were known for this class of digraphs. The proposed method is also applicable to mixed graphs containing directed and undirected edges. [ABSTRACT FROM AUTHOR]

This paper shows how branch-and..bound methods can be used to reduce storage and, possibly, computational requirements in discrete dynamic programs. Relaxations and fathoming criteria are used to identify and to eliminate states whose corresponding subpolicies could not lead to optimal policies. The general dynamic programming/branch-and-bound approach is applied to the traveling-salesman problem and the nonlinear knapsack problem. Our computational experience demonstrates that the hybrid approach yields dramatic Savings in both computer storage and computational requirements. [ABSTRACT FROM AUTHOR]

Given the widespread use of the hub and spoke network architecture and its growing importance to competitiveness in logistics, communication, and mass transportation, there has been considerable interest by practitioners and researchers alike in finding efficient methods for designing such networks. This paper provides a method that delivers both high quality solutions and firm measures of that quality, and allows problems to be solved in reasonable time on a desktop computer. The approach begins with a previously proposed tight linear programming formulation and uses subgradient optimization on a lagrangian relaxation of the model. However, to dramatically improve the performance of this approach, we augment a subproblem of the lagrangian relaxation model with a cut constraint. In computational experiments on eighty-four standard test problems, average gaps are 0.048%. Maximum gaps are under 1% while average solution times on a Pentium-166 are under five minutes. [ABSTRACT FROM AUTHOR]

This research investigates the problem of allocating database fragments across a set of computers connected by a communication network. A mathematical model is presented to aid designers in the development of distributed database systems. The model takes into account the pattern of usage of the databases, communication costs in the network, delays due to queuing of data requests, costs for maintaining consistency among the various copies of a database, and storage costs. A solution procedure based on Lagrangian relaxation is proposed to solve the model. Computational results are reported along with several useful observations. The model is applicable to organizations that are considering migration from a centralized to a distributed computing environment. [ABSTRACT FROM AUTHOR]

The article discusses fabric computing, which the article defines as server capabilities and advanced networking combined into one highly available, scalable fabric, allowing users to work with it as needed. Reconfigurable pools of communications, networks, and computing resources are created, the article indicates. Topics include the partial implementation of the concept of grid and virtualization computing as well as geographically dispersed computers. Also discussed are organizations that can maximize their local computing resources.

The author discusses his experiences teaching computer science to engineers in Peru. South America nations received computer technology later than other industrialized nations. The U.S. National Research Council noted that economic factors such as unequal income distribution and ethnic inequalities were hindering industrialization. The author comments on the installation of a computer network into a lead-zinc mine for use in planning mining production. The computer was programmed with an algorithm to create mining plans for engineers. The author describes his attempts to teach the engineers to operate the computer despite a language barrier. A network connection installed in Peru allowed mine engineers to exchange communication and receive technical information.

In this paper, we provide a simple proof that the distributions of an input and an output interval in a stationary Jackson network of single server nodes are equivalent. The proof also applies to Gordon and Newell networks of single server nodes. The proof's key idea is that the reverse process of a Jackson network's stationary queue length process is also a Jackson network's stationary queue length process. [ABSTRACT FROM AUTHOR]

An essay is presented on polymerization reaction engineering's mathematical tools and approaches. It notes the significance of these mathematical approaches and tools for polymer reaction technology development. It attributes the detailed mathematical models' implementation to rapid computer resource evolution.