Journal:Informatica
Volume 26, Issue 3 (2015), pp. 453–472
Abstract
Recently, XML has achieved the leading role among languages for data representation and, thus, the amount of related technologies and applications exploiting them grows fast. However, only a small percentage of applications is static and remains unchanged since its first deployment. Most of the applications change with newly coming user requirements and changing environment. In this paper we describe a framework and a methodology for management of evolution and change propagation throughout XML applications. We also describe its proof-of-concept implementation called eXolutio, which has been developed and improved in our research group during last few years. The text should help the reader to get acquainted with the target area of XML evolution and the approach we have proposed and implemented.
Journal:Informatica
Volume 26, Issue 3 (2015), pp. 435–451
Abstract
An effective way for managing and controlling a large number of inventory items or stock keeping units (SKUs) is the inventory classification. Traditional ABC analysis which based on only a single criterion is commonly used for classification of SKUs. However, we should consider inventory classification as a multi-criteria problem in practice. In this study, a new method of Evaluation based on Distance from Average Solution (EDAS) is introduced for multi-criteria inventory classification (MCIC) problems. In the proposed method, we use positive and negative distances from the average solution for appraising alternatives (SKUs). To represent performance of the proposed method in MCIC problems, we use a common example with 47 SKUs. Comparing the results of the proposed method with some existing methods shows the good performance of it in ABC classification. The proposed method can also be used for multi-criteria decision-making (MCDM) problems. A comparative analysis is also made for showing the validity and stability of the proposed method in MCDM problems. We compare the proposed method with VIKOR, TOPSIS, SAW and COPRAS methods using an example. Seven sets of criteria weights and Spearman’s correlation coefficient are used for this analysis. The results show that the proposed method is stable in different weights and well consistent with the other methods.
Journal:Informatica
Volume 26, Issue 3 (2015), pp. 419–434
Abstract
A secure and high-quality operation of power grids requires frequency to be managed to keep it stable around a reference value. The deviation of the frequency from this reference value is caused by the imbalance between the active power produced and consumed. In the Smart Grid paradigm, the balance can be achieved by adjusting the demand to the production constraints, instead of the other way round. In this paper, an swarm intelligence-based approach for frequency management is proposed. It is grounded on the idea that a swarm is composed of decentralised individual agents (particles) and that each of them interacts with other ones via a shared environment. Three swarm intelligence-based policies ensure a decentralised frequency management in the smart power grid, where agents of swarm are making decisions and acting on the demand side. Policies differ in behaviour function of agents. Finally, these policies are evaluated and compared using indicators that point out their advantages.
Journal:Informatica
Volume 26, Issue 3 (2015), pp. 407–417
Abstract
The concept of stratified graph introduces some method of representation which can be embedded with an interpretation mechanism in order to obtain objects from some knowledge domain based on the considered symbolic graph-based representations. As it was defined in the literature, the inference process uses the paths of the stratified graphs, an order between the elementary arcs of a path and some results of universal algebras. The order is defined by considering a structured path instead of a regular path. In a previous paper the concept of system of knowledge representation was defined. It includes a stratified graph G, a partial algebra Y of objects, an injective mapping that embeds the nodes of G into objects of Y and a set of algorithms that takes pairs of objects from Y to get some other object of Y. In this paper the inference process defined for such a system of knowledge considers the interpretation of the symbolic elements of a stratified graph as formal language constructions. The concepts introduced in this paper can initiate a possible research line concerning the automatic generation mechanism for formal languages.
Journal:Informatica
Volume 26, Issue 3 (2015), pp. 389–406
Abstract
The purpose of this study is to apply the method of hybrid multiple criteria decision making (MCDM) to select public relations personnel for tourism industry in Taiwan. Fuzzy Delphi method, which can lead to better criteria selection, is used to modify criteria. Considering the interdependence among the selection criteria, analytic network process (ANP) is then used to obtain the weights of them. To avoid calculation and additional pairwise comparisons of ANP, technique for order preference by similarity to ideal solution (TOPSIS) is used to rank the alternatives. The use of a combination of fuzzy Delphi method, ANP and TOPSIS, proposing a MCDM model for public relations personnel selection, and applying these to a real case is the unique features of this study.
Journal:Informatica
Volume 26, Issue 3 (2015), pp. 369–388
Abstract
In order to compete in the global environment, a manufacturing company has to keep developing new technologies. Selection of a right technology is a critical stage in a successful technology transfer process. However, technology selection is a complex multi-dimensional problem including both qualitative and quantitative factors, such as human resources, operational and financial dimensions, which may be in conflict and may also be uncertain. In addition, interdependent relationships exist among various dimensions as well as criteria of technology selection. The identified problems could be solved by combining multiple criteria decision making (MCDM) methods of different nature and fuzzy set theory. The objective of the current paper is to develop a complex approach to evaluate technologies and to rank their appropriateness for a company. A hybrid model is proposed, based on Fuzzy Analytic Network Process (FANP) and Fuzzy Technique for Order Preference by Similarity to Ideal Solution (FTOPSIS). A real-life case study is presented to validate the proposed model.
Journal:Informatica
Volume 26, Issue 2 (2015), pp. 357–367
Abstract
Abstract
An efficient supervised orthogonal nonlinear dimensionality reduction algorithm, namely orthogonal margin maximization projection (OMMP), is presented for gait recognition in this paper. Taking the local neighborhood geometry structure and class information into account, the proposed algorithm aims to find a projecting matrix by maximizing the local neighborhood margin between the different classes and preserving the local geometry structure of the data. After projecting, the data points in the same class are pulled as close as possible, while the data points in different classes are pushed as far as possible. The highlights of OMMP include (1) takes both of the local information and class information of the data into account; (2) considers the effect of the noisy points and outliers; (3) it is supervised and orthogonal; and (4) its physical meaning is very clear. The experimental results on a public gait database show the effectiveness of the proposed method.
Journal:Informatica
Volume 26, Issue 2 (2015), pp. 335–355
Abstract
Abstract
This paper proposes an extension of the ARAS method which, due to the use of interval-valued fuzzy numbers, can be more appropriate for solving real-world problems. In order to overcome the complexity of real-world decision-making problems, the proposed extension also includes the use of linguistic variables and a group decision making approach. In order to highlight the proposed methodology an example of a faculty websites evaluation is considered.
Journal:Informatica
Volume 26, Issue 2 (2015), pp. 313–334
Abstract
Abstract
In this paper we consider optimal congestion control and routing schemes for multipath networks with non-congestion related packet losses which can be caused by, for example, errors on links on the routes, and develop a relaxed multipath network utility maximization problem. In order to obtain the optimum, we present a primal algorithm which is shown to be globally stable in the absence of round-trip delays. When round-trip delays are considered, decentralized sufficient conditions for local stability of the algorithm are proposed, in both continuous-time and discrete-time forms. Finally, a window-flow control mechanism is presented which can approximate the optimum of the multipath network utility maximization model.
Journal:Informatica
Volume 26, Issue 2 (2015), pp. 283–312
Abstract
Abstract
This paper presents a novel approach to the adaptation of multidimensional data models to user-specific needs. The multidimensional data models used in contemporary business-intelligence systems are inherently complex. In order to reduce the complexity of these models, we propose using a qualitative multiple-criteria decision modelling method that is based on using a hierarchical tree of the criteria to decompose the larger problem into a group of smaller problems. The final value is derived by aggregating the criteria values using simple “if-then” rules, which form the knowledge-based expert rules in the hierarchical criteria tree that reflect users’ preferences. The multiple-criteria analysis of the multidimensional model structure results in a multidimensional model that exhibits a reduced complexity and is adapted to users’ needs. The model was validated using sales data from a medium-size enterprise. The qualitative (through questionnaires) and the quantitative (through usage mining) evaluation of the proposed methodology both showed that the proposed approach increases the ease-of-use of business intelligence systems and also contributes to a higher user satisfaction.