Monthly Archives: May 2011

Narrowband Interference Suppression Methods and Algorithms in OFDM Communications

Miglen Ovcharov

Abstract: In this paper, the basic Narrowband Interference Suppression methods and algorithms in Single Input Single Output (SISO) digital Orthogonal Frequency Division Multiplexing (OFDM/DMT) communication systems are considered. The overviewed methods are applicable for both wireless OFDM and wire-line DSL DMT communication systems.

Key words: NBI, RFI, OFDM, DMT, DSL, Digital Communications, Digital Filters.
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Open Access to User Data Management Ivaylo Atanasov

Abstract: Opening nefrvor/‹ interfaces allows enterpr/se applications to access communication functions in public networks. The paper presents a research› on capabilities for open access to ‹/ser data manapemenf through application programming interfaces.  The requirements  for open access to data stored in user profile server dep/oyed in the network are analyzed. An approach to design of application programming interfaces for user data manage/r›en/ is s‹/gges/ed. Functional mapping of interface reel/›ods onto ne/vv’or/‹ control protocol messages is studied. L/ser profile service data model  is  suggested.  A  use  case is  considered.

Key words: Open Service Access, Application  Programming  Interfaces,  Generic Profile,Data Convergence, Internet Protocol Multimedia  Subsystem

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Parallel Algorithms and Software for Searching Information System by Two Attributes

Stoicho Stoichev, Svetlana Marinova

Abstract:The paper investigates the problem of parallel search by multiple attributes in an information system, designed for shared-memory parallel arch//ec/‹/res. Searching by multiple a//ribu/es is a common operation in databases and applying parallel search algorithms can acce/erate the execution in large databases. The existing para//e/ search algorithms based on multiple a//rid‹/fes are designed mainly for dis/ribr/fed-memory systems. We propose three new parallel algorithms for searching by two attributes, de/erm/ne theoretically their lime complexity and evaluate experimentally their performance on a multi-core processor. The algorithms are applicable for searching an array of records, sorted with a para//e/ algorithm for bucket sort. T/›e experiments show that the proposed parallel algorithms  achieve speedr/p in most of the cases compared to a sequential searc/› algorithm. T/›e parallel algorithms based on bucket  sort  can  acce/era/e significantly //›e searc/› in situations of unsuccessful search and key distributions, c/ose /o  the uniform distribution. Based on the conducted experiments, we make recommendations for improvements of the parallel searc/› algorithms that are subject of a future work.

Key words: Algorithm, database, information sysfem, multi-core, multiprocessor, parallel, query, search
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Instruction in Informatics for Mechanical Engineering Faculties at Universities – Challenge or Necessity

Ludmila Stoyanova, Daniela Minkovska

Abstract: This paper reveals some problems of the education in Informatics at Universities for Mechanical engineering faculties. The curricula content has been discussed and compared with the needs o/ the students’ further study at the Un!versity and their future work. An analysis of studied programming languages in Bulgaria and in many countries in Europe, North America and Asia has been made in connection with the further professional needs of the  students.  Additionally  the res‹//is of students’ attitude towards f/›e programming languages have been analyzed. At //›e end conclusions have been  made for the temporary requirements towards the programming language for mechanical engineering faculties at the Technical University.

Key words: education, informatics, mechanical engineering, programming language
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System for Voice Control of Car Modules with Communication through CAN Network

Dimityr Stoimenov, Philip Petrov

Abstract:A system for development, installation and practical testing of control of car electronic modules through voice commands is presented. The system is capable of having configuration for different car models with different CAN network specifications. There is an intuitive and easy to use user interface with //exib/e navigation. The system is presented  and defended as bachelor’s thesis in Technical University Sofia, in Faculty of Compr/ter Systems and Technologies in 2010.

Key words: voice commands, voice control, cars, automobiles,  CAN network, software
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Electronic Conferencing — State of the Art and Applications

Roumen Trifonov

Abstract:The paper era/rra/es the  main challenges of videoconferencing for e//ecfive business support. Description ot functionalities of electronic conferencing systems is made and comparaf/ve analysis o/ I/›e most famous e-conferencing systems is done. End-user products finding on the market are presented according to the dynamics of deve/opmenf of these systems and fast increasing of //›e interest and implementations.

Key words: electronic  conferencing,  videoconferencing,  telepresence.
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Software Visualization for Fast Orientation in Complex Information Systems

Haralambi Haralambiev, Stanimir Boichev, Milena Lazarova, Ognyan Nakov

Abstract: ’ The paper presents the problems of software visualization of complex information systems. Based on I/›e research analyses and definition of the requirements for the visualization system a concept for interactive s/at›c software visualization was developed in which static software analysis to be combined with filtering, clustering and the possibility of user inferacfion fo obtain a visualization that supports the understanding and the orientation in the software structure.

Key words: software visualization, visualization tools, interactive visualization, static visualization
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OLAP Database Optimization Using Stored Procedures

Daniela Gotseva, Veska Gancheva

Abstract: The investigations  presented  in this paper,  are a/med to optimization  of database that are  used  for  storing  data  using  OLAP  cubes.  the possibilities  for optimization  using  views and indexes arc presented. Solutions for query optimization using storecl procedures are supges/ed. 

Key words: database, database se/ver, index, query, optimization,  OLAP, stored procedures.

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Secret Sharing Based on the Residue Theorem

Boncho Aleksandrov, Nina Sinjagina, Petko Kotchevski

Abstract: In the present paper different characteristics of Shamir’s method for secre/ reconstruction and sharing are analyzed. A method for shared storage and reconstruction of secre/ information, based on the residue theorem, is proposed. By using the features of the  resid//e theorem, some of the shortcomings of Shamir’s scheme have been eliminated.  The proposed method makes it possible to identify the cases in which the shared secret has  been incorrectly reconstructed

Key words: secret sharing, data profection, user identification.

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Parallel Biological Sequence Alignment Based on Smith-Waterman Algorithm

Plamenka Borovska, Veska Gancheva, Ivailo Georgiev

Abstract: The effective comparison of biological data sequences is an important and a challenging task in bioinformatics. The process itself is a way of arranging DNA, RNA or protein sequences in order /o identify similar areas that may have a consequence of functional, structural or evolutionary re/a/ions between them. Smi//›-Waterman algorithm, based on dynamic programming has become
//›e most fundamental in bioinformatics. T/›e goal o I this paper is to inves/igafe the efficiency of
parallel multithreaded implementation based on Smith-Waterman algorithm. Performance parameters have been estimated by the experiments using various data sets and BLOSUM matrixes.
Key words: alignment, biological sequences, parallel algorithms, Smith- Waterman.

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