Angelo Sifaleras

E-Learning Technologies: Employing Matlab Web Server to Facilitate the Education of Mathematical Programming.

This paper presents new web-based educational software (webNetPro) for Linear Network Programming. It includes many algorithms for Network Optimization problems, such as shortest path problems, minimum spanning tree problems, maximum flow problems and other search algorithms. Therefore, webNetPro can assist the teaching process of courses such as Graph Theory or Network Optimization, Algorithms or Data Structures. Since the Matlab web server is part of the underlying infrastructure, the end user need not use Matlab directly. The approach exploits transparently the benefits of the Matlab programming environment through a straightforward web interface. Furthermore, webNetPro is platform independent. Thus, it can be viewed as a powerful supplement to traditional instruction techniques and can be used without significant difficulties in distance education. Benefits and drawbacks are thoroughly described in order to support the significance of this tool in distance learning.

A hybrid Particle Swarm Optimization – Variable Neighborhood Search algorithm for Constrained Shortest Path problems

In this paper, a well known NP-hard problem, the Constrained Shortest Path problem, is studied. As efficient metaheuristic approaches are required for its solution, a new hybridized version of Particle Swarm Optimization algorithm with Variable Neighborhood Search is proposed for solving this significant combinatorial optimization problem. Particle Swarm Optimization (PSO) is a population-based swarm intelligence algorithm that simulates the social behavior of social organisms by using the physical movements of the particles in the swarm. A Variable Neighborhood Search (VNS) algorithm is applied in order to optimize the particles’ position. In the proposed algorithm, the Particle Swarm Optimization with combined Local and Global Expanding Neighborhood Topology (PSOLGENT), a different equation for the velocities of particles is given and a novel expanding neighborhood topology is used. Another issue in the application of the VNS algorithm in the Constrained Shortest Path problem is which local search algorithms are suitable from this problem. In this paper, a number of continuous local search algorithms are used. The algorithm is tested in a number of modified instances from the TSPLIB and comparisons with classic versions of PSO and with other versions of the proposed method are performed. Also, the results of the algorithm are compared with the results of a number of metaheuristic and evolutionary algorithms. The results obtained are very satisfactory and strengthen the efficiency of the algorithm.

Recent advances delivered by HTML 5 in mobile cloud computing applications: a survey

With the explosive growth of the mobile applications and emerging of Cloud Computing (CC) concept, Mobile Cloud Computing (MCC) has been introduced to be a potential technology for mobile services. MCC refers to an infrastructure where both the data storage and the data processing happen outside of the mobile device. One of the technologies that will advance MCC is the latest version of the Webs markup language, HTML 5. In this paper, we present a survey of new HTML 5 features with a focus on the enhancement of the current MCC limitations. Specifically, we present the most important features of HTML 5 organized in different categories and their contribution in the deployment of MCC applications. Finally, the results of the research carried out on evaluating HTML 5 in terms of a wide range of applications and specifications are reviewed.

An exterior simplex type algorithm for the Minimum Cost Network Flow Problem

In this paper a new Network Exterior Point Simplex Algorithm (NEPSA) for the Minimum Cost Network Flow Problem (MCNFP) is analytically presented. NEPSA belongs to a special simplex type category and is a modification of the classical network simplex algorithm. The main idea of the algorithm is to compute two flows. One flow is basic but not always feasible and the other is feasible but not always basic. A complete proof of correctness for the proposed algorithm is also presented. Moreover, the computational behavior of NEPSA is shown by an empirical study carried out for randomly generated sparse instances created by the well-known GRIDGEN network problem generator.

Variable neighborhood descent heuristic for solving reverse logistics multi-item dynamic lot-sizing problems

The multi-product dynamic lot sizing problem with product returns and recovery is an important problem that appears in reverse logistics and is known to be NP-hard. In this paper we propose an efficient variable neighborhood descent heuristic algorithm for solving this problem. Furthermore, we present a new benchmark set with the largest instances in the literature. The computational results demonstrate that our approach outperforms the state-of-the-art Gurobi optimizer. HighlightsTackle the multi-product dynamic lot sizing problem with product returns and recovery.Investigate for the first time a VND approach for this NP-hard problem.Present a new benchmark set with the currently largest instances in the literature.Propose a self-contained solver without any link to other callable library API.The proposed VND heuristic outperforms the state-of-the-art Gurobi optimizer.

An empirical study on factors influencing the effectiveness of algorithm visualization

The determination of the factors influencing the effectiveness of algorithm visualization poses an interesting research question. In this paper, we present the results of a longitude empirical study regarding this question. The study was based on an evaluation of the Visual LinProg educational tool inside classrooms. Visual LinProg is a web‐based educational tool, which solves linear programming problems using animation and visualization techniques. Visual LinProg was developed to be used in linear programming courses to supplement the teaching. Our empirical study is based on questionnaires that include quantitative and qualitative topics. This evaluation first indicates that Visual LinProg facilitates the learning of the revised simplex algorithm and second presents more results on factors influencing the understanding of this algorithm by the students/users of the Visual LinProg.

General variable neighborhood search for the multi-product dynamic lot sizing problem in closed-loop supply chain

Abstract The multi-product dynamic lot sizing problem with product returns and recovery is an important problem that appears in reverse logistics and is known to be NP-hard. In this paper we suggest a General Variable Neighborhood Search (GVNS) metaheuristic algorithm for solving this problem. It is the first time that such an approach is used for this problem in the literature. Furthermore, we present some encouraging computational results obtained on a new set of very large benchmark instances, compared with Gurobi optimizer.

Convergence of Internet of things and mobile cloud computing

As an integral element of future Internet, Internet of things (IoT) could be described as a real-world interaction with everything connected via intelligent network infrastructure and advanced communication technologies. Mobile cloud computing (MCC), on the other hand, offers an infrastructure wherein both data storage and data processing take place outside of the mobile device. As a more mature infrastructure, MCC offers several advantages, while the relatively new IoT has several limitations. In this paper, we present a survey of IoT limitations and MCC advantages. Specifically, we present the most advantageous aspects of MCC and how they alleviate the limitations of IoT. Furthermore, we discuss several IoT-enabled business services to highlight the benefits of converging IoT and MCC.

Combining the priority rankings of DEA and AHP methodologies: a case study on an ICT industry

This article presents a case study on how data envelopment analysis DEA and analytic hierarchy process AHP could be combined to produce priority rankings for a set of companies. The shortcomings of each method, when exclusively used to deal with multiple criteria decision analysis MCDA problems, are also analysed. The dataset of this study, arising from the European Union EU Industrial RD following that, ranking of the efficient companies could be attained through AHP.

Teaching Note—An Animated Demonstration of the Uncapacitated Network Simplex Algorithm

Operations Research (OR) instructors use visualizations to help teach graph algorithms and data structures. Algorithm visualization is an illustration of abstract concepts included in computer algorithms, making use of either static or dynamic (animated) computer graphics. In this paper we present new software that includes an animated demonstration of the uncapacitated primal network simplex algorithm. The aim of the animation software is twofold. First, it aims to help OR students understand the algorithm. The algorithm is difficult to grasp for many students because it generates a sequence of rooted trees. Second, it aims to enable OR instructors to explain each iteration of the algorithm visually with minimal effort. The software can be used in combinatorial optimization, graph theory, and similar courses. The software has been implemented as a Java applet, is freely available and highly interactive, and can be accessed through the Web. The software shows the solution process through textual informati...