Journal:Informatica
Volume 19, Issue 1 (2008), pp. 81–100
Abstract
This paper presents a bimodal biometric verification system based on the fusion of palmprint and face features at the matching-score level. The system combines a new approach to palmprint principal lines recognition based on hypotheses generation and evaluation and the well-known eigenfaces approach for face recognition. The experiments with different matching-score normalization techniques have been performed in order to improve the performance of the fusion at the matching-score level. A “chimerical” database consisting of 1488 palmprint and face image pairs of 241 persons was used in the system design (440 image pairs of 110 persons) and testing (1048 image pairs of 131 persons). The experimental results show that system performance is significantly improved over unimodal subsystems.
Journal:Informatica
Volume 19, Issue 1 (2008), pp. 63–80
Abstract
This paper presents the application of multi-criterion approach to the analysis and comparison of reference alternatives of wind power park information system (WPPIS) which complies with the standard IEC 61400-25. The comparison is based on multi-criterion preferences measured in domination rate (index). The reference alternatives include centralized, mixed and seamless communication topologies. The major features of these alternatives are discussed as well as the multi-criterion methodology applied covering pair comparison, Pareto sets and fuzzy sets methods. The current investigation described is an extension of the preceding investigation of the same reference alternatives of WPPIS. As we have showed, the transition from the concerted experts view as it was a case in previous investigation to the conflicting expert views in the current investigation proved the high robustness of solution made for the case of concerted expert views: the rank of preferences for alternatives remained the same, with seamless communication topology on the top the rank.
Journal:Informatica
Volume 19, Issue 1 (2008), pp. 45–62
Abstract
The aim is to investigate two emerging information technologies in graduate studies and scientific cooperation. Internet is the first technology. The open source is the second. They help each other in many ways. The joint influence of both is regarded in this paper.
Results of complexity theory show the limitations of exact analysis. That explains popularity of heuristic algorithms. It is well known that efficiency of heuristics depends on the parameters. Therefore automatic procedures for tuning the heuristics help to compare results of different heuristics and enhance their efficiency.
The theory and some applications of Bayesian Approach were discussed in (Mockus, 2006a). In this paper examples of Bayesian Approach to automated tuning of heuristics are investigated. This is the Bayesian Heuristic Approach, in short. The examples of traditional methods of optimization, including applications of linear and dynamic programming, will be investigated in the next paper. These three papers represents three parts of the same work. However each part can be read independently.
All the algorithms are implemented as platform independent Java applets or servlets. Readers can easily verify and apply the results for studies and for real life optimization problems.
The theoretical result is application of unified Bayesian Heuristic Approach for different discrete optimization models. The practical result is adaptation of these models for graduate distance studies and scientific collaboration by a common java global optimization framework.
The software is regularly updated and corrected responding to new programming tools and users reports. However the general structure of web sites remains. The information is on the web site: http://pilis.if.ktu.lt/~mockus and four mirror sites.
Journal:Informatica
Volume 19, Issue 1 (2008), pp. 31–44
Abstract
This paper presents a method of minutiae based fingerprint matching that is robust to deformations and does not do fingerprint alignment. It concentrates on comparing rotation and translation invariant local structures defined by minutiae point and its neighboring minutiae points. Then the collection of most probable correspondences of matched minutiae is found. Finally, the local structures of higher order are validated. All three steps are completely rotation and translation invariant, robust to nonlinear deformations and do not use any fingerprint alignment. Experimental results on publicly available as well as internal databases show an improved performance of the proposed method in comparison with the traditional minutiae based algorithms that perform fingerprint registration.
Journal:Informatica
Volume 19, Issue 1 (2008), pp. 17–30
Abstract
Abstract data types constitute a central tool in computer science and play an important role in problem solving, knowledge representation, and programming. In this paper, formal and practical aspects of utilizing abstract data types (ADTs) are discussed in the context of logic programming when using the Prolog programming language. The approach is presented in the following stages: (a) First, alternative ways of implementing ADTs in terms of Prolog constructs are presented and partial encapsulation of ADTs in terms of grey boxes is demonstrated. (b) Next, complete encapsulation of ADTs in terms of black boxes is suggested in a way that strictly reflects the concept's formal computer science definition while taking into consideration the characteristics and constraints of the logic programming paradigm. (c) Finally, implications for instruction are discussed.
Journal:Informatica
Volume 19, Issue 1 (2008), pp. 3–16
Abstract
The invention of public-key cryptography makes many new network applications, such as electronic commerce (CE), possible. However, the widely used Internet is open and unprotected. Therefore, verifying the legitimacy of an individual's public key is very important. Most of the key authentication schemes require one or more trustworthy authorities to authenticate the key of a user. Consequently, the system security is mainly dependent on the honesty of these third parties. Unfortunately, a security solution in wide area networks (for example, the Internet) often cannot be applied to local area networks directly without any modification. Sometimes, a complete rebuild is necessary, especially for performance criteria consideration. In this paper, we propose two simple key authentication schemes that require no certification authorities for computer systems in local area networks, in which a host is responsible for user authentication and it uses a designated password authentication mechanism.
Journal:Informatica
Volume 18, Issue 4 (2007), pp. 615–628
Abstract
This paper proposes a reversible data hiding method for error diffused halftone images. It employs statistics feature of pixel block patterns to embed data, and utilizes the HVS characteristics to reduce the introduced visual distortion. The watermarked halftone image can be perfectly recovered if it is intact, only a secret key is required. The method is suitable for the applications where the content accuracy of the original halftone image must be guaranteed, and it is easily extended to the field of halftone image authentication.
Journal:Informatica
Volume 18, Issue 4 (2007), pp. 603–614
Abstract
The paper considers application of stochastic optimization to system of automatic recognition of ischemic stroke area on computed tomography (CT) images. The algorithm of recognition depends on five inputs that influence the results of automatic detection. The quality of recognition is measured by size of conjunction of ethalone image and the image calculated by the program of automatic detection. The method of Simultaneous Perturbation Stohastic Approximation algorithm with the Metropolis rule has been applied to the optimization of the quality of image recognition. The Monte-Carlo simulation experiment was performed in order to evaluate the properties of developed algorithm.
Journal:Informatica
Volume 18, Issue 4 (2007), pp. 585–602
Abstract
Business process engineering is an important part of the advanced enterprise engineering. One of the still open issues is the question how in the enterprise system design to reuse ontological knowledge about business processes. The paper proposes to consider a family of similar business processes as a generic process and to represent knowledge about generic processes in a domain independent way. It describes the main scheme for reuse of such a domain independent knowledge when developing enterprise-wide information systems (IS). The main attention is paid to the process configuration problem. In order to solve this problem, a configurator (human being or machine) must find a set of components that fit together to satisfy the problem specification. An approach based on Description Logics is proposed for this aim. The main contribution of the paper is the proposed process configuration technique.
Journal:Informatica
Volume 18, Issue 4 (2007), pp. 569–584
Abstract
In the paper, a cross-layer optimization between application layer and fabric layer is proposed. The aim is to optimize the end-to-end quality of the dynamic grid application as well as efficiently utilizing the grid resources. The application layer QoS and fabric layer QoS are closely interrelated in Grids since the upper layer service is based on the lower level's capabilities. A fabric level and application level QoS scheduling algorithm is proposed. We formulate the integrated design of resource allocation and user QoS satisfaction control into a constrained optimization problem. The optimization framework provides a layered approach to the sum utility maximization problem. The application layer adaptively adjusts user's resource demand based on the current resource conditions, while the fabric layer adaptively allocates CPU, storage and bandwidth required by the upper layer.