Alexander Penev

Alexander Penev
University of Plovdiv Paisii Hilendarski · Computer Systems

PhD

About

32
Publications
6,407
Reads
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46
Citations
Additional affiliations
October 2018 - present
Plovdiv University "Paisii Hilendarski"
Position
  • Professor (Associate)
September 2000 - October 2018
Plovdiv University "Paisii Hilendarski"
Position
  • Professor (Assistant)
September 1994 - present
Plovdiv University "Paisii Hilendarski"
Position
  • Researcher
Education
May 2007 - August 2013
Plovdiv University "Paisii Hilendarski"
Field of study
  • Computer graphics. Dissertation Thesis "Open hybrid systems for geometric modelling"
October 1991 - October 1996
Plovdiv University "Paisii Hilendarski"
Field of study
  • Computer graphics. Master Thesis "One approach to the description of geometric information”

Publications

Publications (32)
Article
Full-text available
A novel approach is presented for recording high volume data about ray tracing rendering systems' runtime state and its subsequent dynamic analysis and interactive visualization in the algorithm computational domain. Our framework extracts light paths traced by the system and leverages on a powerful filtering subsystem, helping interactive visualiz...
Conference Paper
Full-text available
Differentiation is ubiquitous in high energy physics, for instance in minimization algorithms and statistical analysis, in detector alignment and calibration, and in theory. Automatic differentiation (AD) avoids well-known limitations in round-offs and speed, which symbolic and numerical differentiation suffer from, by transforming the source code...
Article
Full-text available
The present paper describes an approach to geometric modelling, in which the representation of solids is hybrid and consists of an easily expand-able collection of representations. We also consider an experimental prototype of a framework for the development of systems for geometric modelling based on open hybrid representation schemes. We present...
Preprint
C++ Modules come in C++20 to fix the long-standing build scalability problems in the language. They provide an io-efficient, on-disk representation capable to reduce build times and peak memory usage. ROOT employs the C++ modules technology further in the ROOT dictionary system to improve its performance and reduce the memory footprint. ROOT with C...
Article
Full-text available
Debugging is a very time consuming task which is not well supported by existing tools. The existing methods do not provide tools enabling optimal developers' productivity when debugging regressions in complex systems. In this paper we describe a possible solution aiding differential debugging. The differential debugging technique performs analysis...
Article
Full-text available
C++ Modules, one of the new features of C++20, aim to fix the long-standing build scalability problems in the language. They provide an IOefficient, on-disk representation capable to reduce build times and peak memory usage. ROOT already employs the C++ modules technology in its dictionary system to improve performance and reduce the memory footpri...
Conference Paper
Full-text available
Collaboration in research is essential for saving time and money. The field of high-energy physics (HEP) is no different. The higher level of collaboration the stronger the community. The HEP field encourages organizing various events in format and size such as meetings, workshops and conferences. Making attending a HEP event easier leverages coope...
Article
Full-text available
This article discusses the visualization approach applied to the experimental geometric modeling system F-Rep Designer 2.0. This system uses the Functional Representation (F-Rep) scheme in order to describe the model. In our approach the scene/model, the ray tracing algorithm, the shading model, and all that is necessary for the visualization are c...
Article
Full-text available
The main aim of the paper is comparing the speed of calculation for a particular problem for fractional differential equations by parallel CUDA cores. The approximate solv- ing of the initial value problem for scalar nonlinear Riemann-Liouville fractional differential equation is based on a suggested iterative scheme for constructing sequences of u...
Article
Full-text available
This paper presents a framework, SolidOpt, which helps the automated and dynamic lifelong optimization of software systems. Usually, optimizations are a virtue of the (optimizing) compilers. We suggest moving out the optimization facilities and making them more accessible even to end-users during the entire program life cycle. In order to achieve b...
Conference Paper
Full-text available
The paper presents a computer application for 3D geometric modelling based on Function representation scheme (F-Rep). This application called F-Rep Designer uses a platform independent hybrid CPU/GPGPU implementation of Ray tracing algorithm for interactive visualization of the 3D scene during modelling by users. One of the major features of the cu...
Thesis
Full-text available
In this dissertation we present an approach to geometric modelling, in which the description of solids is hybrid and consists of an easily expandable collection of representations. We describe the architecture, design, stages of development and possible use of an open, flexible, distributed, multi-user, hybrid system for geometric modelling based o...
Conference Paper
This paper discusses building up a framework, which helps the automated and dynamic optimization of the software. Disadvantages of existing frameworks and systems are described. We determine the underlying main ideas and principles in the development of SolidOpt framework. The advantages and the need of using multiple models are discussed. We sugge...
Article
Full-text available
We propose a heuristic algorithm for existence of null-submatrices in big sparse matrices. The algorithm is reflexive: it examines its own memory consumption, which is in correlation with its output.
Conference Paper
Full-text available
Article describes the union of architectural pattern MVC and five-layer architecture for geometric modelling. Main purpose is crea-tion of high-modular interactive systems. The implementation includes different reusable object-oriented design patterns and shows a possible application of the architectural union.
Conference Paper
Full-text available
We discuss several aspects of the Computer graphics education in PU "Paisii Hilendarski". In addition, overview of the basic properties and possible applications in education of the hybrid system for geometric modelling OpenF is added. The student interest in Computer graphics course and its novelties are explored. We made analyses and conclusions...
Article
Full-text available
We propose a new, heuristic algorithm for the rook problem. The algorithm is refexive: it examines its own running-time, which is in correlation with the output.
Conference Paper
Full-text available
This paper treats some aspects of configuring applications, libraries, and object classes. We are proposing heterogeneous and structured approach, to define para­ meters of the systems, based on hierarchies of attribute-value (pairs) with addi­tional metadata. This approach uses multiple levels and multiple formats of the configuration sources (fil...
Article
Full-text available
Due to its great variety of applications, the packing problem attracted our attention. The problem is reduced via a graph-theoretic interpretation (searching for cliques in a graph) to searching for a submatrix of a special kind. An algorithm is constructed by means of self-monitoring, which is suitable for real-world problems.
Conference Paper
Full-text available
This paper presents some basic concepts of F-Rep and R-Functions used in com-puter graphics. Here we made short comparison of B-Rep and F-Rep. We also discuss advantages and some important development aspects of so-called hybrid systems. We consider goals, directions, and applications of the developed, by the authors, experimental open hybrid syste...
Conference Paper
Full-text available
Architecture and possible stages in developing of an open, flexible, distributed, multi-user, hybrid system for geometric modeling are considered in the following article. System requirements and its possible applications are also discussed.
Article
Full-text available
N работници и N работи. За всеки работник е указано кои работи може да извършва и кои не. Да се разпределят работите така, че всеки работник да извършва само една работа и всяка работа да се извършва само от един работник. Тази задача е частен случай на известната задача за назначенията. В общия случай е дадена ефективността, с която всеки работник...
Article
The article treats an assignment problem – the so-called rook problem. A new algorithm has been found that uses some methods and techniques from the linear algebra. The algorithm is suitable for a computer realization.
Conference Paper
Full-text available
В статията се разглежда една комбинаторна задача от типа проблеми на присвояване. Предлага се нов алгоритъм за нейното решаване, който използва методи и техники от линейната алгебра. Алгоритъмът е даден във вид, удобен за изпълнение от компютър.

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Cited By

Projects

Projects (2)
Project
Automatic differentiation (AD) avoids well-known limitations in round-offs and speed, which symbolic and numerical differentiation suffer from, by transforming the source code of functions. Clad enables automatic differentiation (AD) for C++. It is based on LLVM compiler infrastructure and is a plugin for Clang compiler. Clad is based on source code transformation. Given C++ source code of a mathematical function, it can automatically generate C++ code for computing derivatives of the function. It supports both forward-mode and reverse-mode AD.
Project
The main objective is the study of visual programming languages (VPL). Experiments are mainly in the direction Openness, Interactivity and Dynamics of visual programming languages. The project deals with visual programming languages (and visual programs) as a subject, environment and tool for static and dynamic analysis of computer programs.