Tabitha L. James

Virginia Polytechnic Institute and State University, Blacksburg, Virginia, United States

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Publications (17)13.65 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Our increased reliance on digital information and our expansive use of the Internet for a steadily rising number of tasks requires that more emphasis be placed on digital information security. The importance of securing digital information is apparent but the success in persuading individual users to adopt and utilize tools to improve security has been arguably more difficult. In this study, we propose a number of factors that may influence individual security practices. These constructs are developed by adapting existing theory from information security and privacy research to examine information security behaviors in the general public dimension. The influence of these factors on perceived need and actual behavior is then examined. The resulting model is shown to fit well and support is found for many of the proposed relationships. The determination of the antecedents of individual digital security practices may provide useful insight to tailoring programs for adoption and utilization of security tools by individuals in the general public dimension.
    Information Technology and Management 06/2013; 14(2). · 0.14 Impact Factor
  • Tabitha James, César Rego
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    ABSTRACT: This paper introduces a new path relinking algorithm for the well-known quadratic assignment problem QAP in combinatorial optimization. The QAP has attracted considerable attention in research because of its complexity and its applicability to many domains. The algorithm presented in this study employs path relinking as a solution combination method incorporating a multistart tabu search algorithm as an improvement method. The resulting algorithm has interesting similarities and contrasts with particle swarm optimization methods. Computational testing indicates that this algorithm produces results that rival the best QAP algorithms. The authors additionally conduct an analysis disclosing how different strategies prove more or less effective depending on the landscapes of the problems to which they are applied. This analysis lays a foundation for developing more effective future QAP algorithms, both for methods based on path relinking and tabu search, and for hybrids of such methods with related processes found in particle swarm optimization.
    IJSIR. 01/2011; 2:52-70.
  • T. James, E. Brown, C.T. Ragsdale
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    ABSTRACT: Many areas of research examine the relationships between objects. A subset of these research areas focuses on methods for creating groups whose members are similar based on some specific attribute(s). The blockmodel problem has as its objective to group objects in order to obtain a small number of large groups of similar nodes. In this paper, a grouping genetic algorithm (GGA) is applied to the blockmodel problem. Testing on numerous examples from the literature indicates a GGA is an appropriate tool for solving this type of problem. Specifically, our GGA provides good solutions, even to large-size problems, in reasonable computational time.
    IEEE Transactions on Evolutionary Computation 03/2010; · 4.81 Impact Factor
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    César Rego, Tabitha James, Fred Glover
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    ABSTRACT: Abstract – In ,this study ,we present ,a new ,tabu ,search ,algorithm ,for the ,quadratic assignment,problem,(QAP) that utilizes an embedded,neighborhood,construction,called anejection,chain. The,QAP is a,well known combinatorial,optimization,problem,most commonly,used,to model,a facility location,problem. The,acknowledged,difficulty of the QAP has,made,it the focus,of many,metaheuristic approaches.,A key component,of any metaheuristic,approach ,is the ,neighborhood ,definition. ,The ,most ,common neighborhood,applied ,to the ,QAP is a ,2-exchange ,(or swap) ,neighborhood. , Ejection chains,provide ,the ,ability ,to constructively create ,larger ,embedded ,neighborhood structures., We ,propose ,a move ,generation ,process ,that ,provides ,a combinatorial leverage effect, where the size of the neighborhood grows multiplicativelywhile the effort offinding,a best,move,in the,neighborhood,grows,only,additively. Our results,illustrate that significant,improvement,in solution quality over the traditional,swap,neighborhood can,be obtained,by the more,complex,moves,possible,with the ejection,chain,approach., Wealso develop two multi-start tabu search algorithms, utilizing the ejection chain approach, to demonstrate the power of embedding this neighborhood construction
    Networks 01/2010; 56:188-206. · 0.65 Impact Factor
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    Tabitha James, Cesar Rego, Fred Glover
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    ABSTRACT: In this study, we introduce a cooperative parallel tabu search algorithm (CPTS) for the quadratic assignment problem (QAP). The QAP is an NP-hard combinatorial optimization problem that is widely acknowledged to be computationally demanding. These characteristics make the QAP an ideal candidate for parallel solution techniques. CPTS is a cooperative parallel algorithm in which the processors exchange information throughout the run of the algorithm as opposed to independent concurrent search strategies that aggregate data only at the end of execution. CPTS accomplishes this cooperation by maintaining a global reference set which uses the information exchange to promote both intensification and strategic diversification in a parallel environment. This study demonstrates the benefits that may be obtained from parallel computing in terms of solution quality, computational time and algorithmic flexibility. A set of 41 test problems obtained from QAPLIB were used to analyze the quality of the CPTS algorithm. Additionally, we report results for 60 difficult new test instances. The CPTS algorithm is shown to provide good solution quality for all problems in acceptable computational times. Out of the 41 test instances obtained from QAPLIB, CPTS is shown to meet or exceed the average solution quality of many of the best sequential and parallel approaches from the literature on all but six problems, whereas no other leading method exhibits a performance that is superior to this.
    European Journal of Operational Research 06/2009; · 2.04 Impact Factor
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    T. James, C. Rego, F. Glover
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    ABSTRACT: The quadratic assignment problem (QAP) is a well-known combinatorial optimization problem with a wide variety of applications, prominently including the facility location problem. The acknowledged difficulty of the QAP has made it the focus of many metaheuristic solution approaches. In this paper, we show the benefit of utilizing strategic diversification within the tabu search (TS) framework for the QAP, by incorporating several diversification and multistart TS variants. Computational results for an extensive and challenging set of QAP benchmark test problems demonstrate the ability of our TS variants to improve on a classic TS approach that is one of the principal and most extensively used methods for the QAP. We also show that our new procedures are highly competitive with the best recently introduced methods from the literature, including more complex hybrid approaches that incorporate the classic TS method as a subroutine.
    IEEE Transactions on Systems Man and Cybernetics - Part A Systems and Humans 06/2009; · 2.18 Impact Factor
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    ABSTRACT: Social networks depict complex systems as graph theoretic models. The study of the formation of such systems (or networks) and the subsequent analysis of the network structures are of great interest. In the business disciplines, the ability to model and simulate a system of individuals interacting to achieve a certain socio-economic goal holds much promise for gathering beneficial insights. We use case-based decision theory to formulate a customizable model of information gathering in a social network. In this model, the agents in the network have limited awareness of the social network in which they operate and of the fixed, underlying payoff structure. Agents collect payoff information from neighbors within the prevailing social network, and they base their networking decisions on this information. Along with the introduction of the decision theoretic model, we developed software to simulate the formation of such networks in a customizable context to examine how the network structure can be influenced by the parameters that define social relationships. We present computational experiments that illustrate the growth and stability of the simulated social networks ensuing from the proposed model. The model and simulation capability allows for the customizable generation of social networks to be used as aids to study various socio-economic phenomena.
    IJVCSN. 01/2009; 1:1-20.
  • IJISP. 01/2008; 2:42-53.
  • Tabitha L. James, Evelyn C. Brown, Kellie B. Keeling
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    ABSTRACT: The machine-part cell formation problem consists of constructing a set of machine cells and their corresponding product families with the objective of minimizing the inter-cell movement of the products while maximizing machine utilization. This paper presents a hybrid grouping genetic algorithm for the cell formation problem that combines a local search with a standard grouping genetic algorithm to form machine-part cells. Computational results using the grouping efficacy measure for a set of cell formation problems from the literature are presented. The hybrid grouping genetic algorithm is shown to outperform the standard grouping genetic algorithm by exceeding the solution quality on all test problems and by reducing the variability among the solutions found. The algorithm developed performs well on all test problems, exceeding or matching the solution quality of the results presented in previous literature for most problems.
    Computers & Operations Research 01/2007; · 1.91 Impact Factor
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    ABSTRACT: With the growing use of mobile communication devices, the management of such technologies is of increasing importance. The registration area planning (RAP) problem examines the grouping of cells comprising a personal communication services (PCS) network into contiguous blocks in an effort to reduce the cost of managing the location of the devices operating on the network, in terms of bandwidth. This study introduces a hybridized grouping genetic algorithm (HGGA) to obtain cell formations for the RAP problem. The hybridization is accomplished by adding a tabu search-based improvement operator to a traditional grouping genetic algorithm (GGA). Results indicate that significant performance gains can be realized by hybridizing the algorithm, especially for larger problem instances. The HGGA is shown to consistently outperform the traditional GGA on problems of size greater than 19 cells.
    Computer Communications. 01/2007;
  • Kellie B. Keeling, Evelyn C. Brown, Tabitha L. James
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    ABSTRACT: Over the past 25 years, the machine-part cell formation problem has been the subject of numerous studies. Researchers have applied various methodologies to the problem in an effort to determine optimal clusterings of machines and optimal groupings of parts into families. The quality of these machine and part groupings have been evaluated using various objective functions, including grouping efficacy, grouping index, grouping capability index, and doubly weighted grouping efficiency, among others. In this study, we investigate how appropriate these grouping quality measures are in determining cell formations that optimize factory performance. Through the application of a grouping genetic algorithm, we determine machine/part cell formations for several problems from the literature. These cell formations are then simulated to determine their impact on various factory measures, such as flow time, wait time, throughput, and machine utilization, among others. Results indicate that it is not always the case that a “more efficient” machine/part cell formation leads to significant changes or improvements in factory measures over a “less efficient” cell formation. In other words, although researchers are working to optimize cell formations using efficiency measures, cells formed this way do not always demonstrate optimized factory measures.
    Engineering Applications of Artificial Intelligence. 01/2007;
  • Tabitha L. James, Reza Barkhi, John D. Johnson
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    ABSTRACT: Many problems in the operations research field cannot be solved to optimality within reasonable amounts of time with current computational resources. In order to find acceptable solutions to these computationally demanding problems, heuristic methods such as genetic algorithms are often developed. Parallel computing provides alternative design options for heuristic algorithms, as well as the opportunity to obtain performance benefits in both computational time and solution quality of these heuristics. Heuristic algorithms may be designed to benefit from parallelism by taking advantage of the parallel architecture. This study will investigate the performance of the same global parallel genetic algorithm on two popular parallel architectures to investigate the interaction of parallel platform choice and genetic algorithm design. The computational results of the study illustrate the impact of platform choice on parallel heuristic methods. This paper develops computational experiments to compare algorithm development on a shared memory architecture and a distributed memory architecture. The results suggest that the performance of a parallel heuristic can be increased by considering the desired outcome and tailoring the development of the parallel heuristic to a specific platform based on the hardware and software characteristics of that platform.
    Engineering Applications of Artificial Intelligence. 01/2006;
  • JOEUC. 01/2006; 18:1-24.
  • Tabitha L. James, Reza Barkhi, John D. Johnson
    Eng. Appl. of AI. 01/2006; 19:843-856.
  • Source
    T. James, C. Rego, F. Glover
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    ABSTRACT: The quadratic assignment problem, a classical combinatorial optimization problem, has garnered much attention due to its many applications and solution complexity. This research represents the first use of parallelization for path relinking within the QAP setting. We used a simple form of path relinking to focus on the parallel implementation's elements and to determine their impact when used with a method of this type. Our computational results demonstrate highly attractive outcomes despite the procedure's simplicity and show in particular the value of a well-designed parallelization process in this context.
    Intelligent Systems, IEEE 08/2005; · 1.93 Impact Factor
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    Sumali J. Conlon, John R. Conlon, Tabitha L. James
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    ABSTRACT: This paper discusses appropriate application areas for natural language interfaces (NLIs) to databases. This requires comparing NLIs with competing approaches, including other user-friendly interfaces, and training of users with less user-friendly interfaces. Also, since NLI technology is still limited, users may need to learn how to use NLIs themselves. This suggests that NLI popularity may snowball at some point, as users become familiar with NLIs. We use a simple prototype NLI to illustrate when NLIs can achieve flexibility unattainable by simpler interfaces. Currently existing commercial NLIs and application-specific customization are also discussed.
    Decision Support Systems. 01/2004;
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    ABSTRACT: The Internet has provided individuals with new means by which to communicate and new forms of entertainment. However, along with these new opportunities come new privacy issues. The increasing awareness of privacy necessitates a deeper examination of what determines an individual's concept of privacy. In this study, we use existing theory to develop an operational model of privacy. We also construct an instrument to test the model and present results. In the current study, we use theory from the social sciences to develop a multi-dimensional model of privacy. We develop a scale to test the model and present some results from conducting a survey analysis. While we find support for the majority of our hypotheses, we do find some interesting occurrences when examining the directions of the relationships. We believe that the insights obtained from the testing of the current model could be applied to future studies in technology usage and adoption. The lack of current research into individual's concept of privacy in the information technology literature and its importance to the field suggests that the development of a model to determine privacy may be interesting to many researchers. METHODOLOGY

Publication Stats

198 Citations
13.65 Total Impact Points

Institutions

  • 2004–2013
    • Virginia Polytechnic Institute and State University
      • Department of Business Information Technology
      Blacksburg, Virginia, United States
  • 2007
    • The University of Arizona
      • Department of Management Information Systems
      Tucson, AZ, United States
    • East Carolina University
      • Department of Engineering
      North Carolina, United States