Numer czasopisma
Computer Science
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ISSN: 1508-2806
e-ISSN:
Data wydania
2016
Rocznik
Vol. 17
Numer
No. 3
Prawa dostępu
Dostęp: otwarty dostęp
Uwagi:
Prawa: CC BY 4.0 
Uznanie autorstwa 4.0 Międzynarodowe (CC BY 4.0)
Strony
Opis
Rocznik czasopisma (rel.)
Rocznik czasopisma
Computer Science
Vol. 17 (2016)
Artykuły numeru (rel.)
Artykuł
Dostęp ograniczony
Application of projection-based interpolation algorithm for non-stationary problem
(2016) Woźniak, Maciej; Paszyński, Maciej
In this paper, we present a solver for non-stationary problems using L? projection and h-adaptations. The solver utilizes the Euler time integration scheme for time evolution mixed with projection-based interpolation techniques for solving the L? projection problem at every time step. The solver is tested on the model problem of a heat transfer in an L-shape domain. We show that our solver delivers linear computational cost at every time step.
Artykuł
Dostęp ograniczony
Automatic portal generation for 3D audio – from triangle soup to a portal system
(2016) Turecki, Piotr; Pędzimąż, Tomasz; Pałka, Szymon; Ziółko, Bartosz
The purpose of this paper is to investigate an algorithm for generating an automatic portal system. This has been accomplished based on a given set of triangles. The proposed solution was designed to enhance the performance of a sound beam-tracing engine. This solution can also be used for other areas where portal systems are applicable. The provided technical solution emphasizes the beam tracing engine’s requirements. Our approach is based on the work of Haumont et al. (with additional improvements), resulting in improved scene segmentation and lower computational complexity. We examined voxelization techniques and their properties, and have adjusted these to fit the requirements of a beam-tracing engine. As a result of our investigation, a new method for finding portal placement has been developed by adjusting the orientation of the found portals to fit the neighboring scene walls. In addition, we replaced Haumont et al.’s prevoxelization step, which is used for erasing geometrical details (for example, thin walls). This was done by smoothing the distance field that, in effect, eliminated incorrectly positioned portals. The results of our work remove the requirement for walls that separate rooms to have a particular thickness. We also describe a method for building a structure that accelerates real-time queries for determining the area where a given point is located. All of the presented techniques allow for the use of larger sized voxels, which increases performance and reduces memory requirements (not only during the preprocessing phase but also during real-time usage). The proposed solutions were tested using scenarios with scenes of varying complexity.
Artykuł
Dostęp ograniczony
Realization of a system of efficient querying of hierarchical data transformed into a quasi-relational model
(2016) Furmanek, Adam; Tokaj, Jakub; Marcjan, Robert; Siwik, Leszek
Extensible Markup Language was mainly designed to easily represent documents, however, it has evolved and is now widely used for the representation of arbitrary data structures. There are many Application Programming Interfaces (APIs) to aid software developers with processing XML data. There are also many languages for querying and transforming XML, such as XPath or XQuery, which are widely used in this field. However, because of the great flexibility of XML documents, there are no unified data storing and processing standards, tools, or systems. On the other hand, a relational model is still the most-commonly and widely used standard for storing and querying data. Many Database Management Systems consist of components for loading and transforming hierarchical data. DB2 pureXML or Oracle SQLX are some of the most-recognized examples. Unfortunately, all of them require knowledge of additional tools, standards, and languages dedicated to accessing hierarchical data (for example, XPath or XQuery). Transforming XML documents into a (quasi)relational model and then querying (transformed) documents with SQL or SQL–like queries would significantly simplify the development of data-oriented systems and applications. In this paper, an implementation of the SQLxD query system is proposed. The XML documents are converted into a quasi-relational model (preserving their hierarchical structure), and the SQL–like language based on SQL-92 allows for efficient data querying.
Artykuł
Dostęp ograniczony
Quality of experience in the context of mobile applications
(2016) Nawrocki, Piotr; Śliwa, Adrian
Mobile devices are among the most-popular means of browsing the Internet, sending and receiving e-mail, and sharing content on social networks. People use mobile devices and the applications installed on them in different situations throughout the day. In order to ensure that users are satisfied with a mobile application, its author has to ensure a high Quality of Experience level. The problem of automatic evaluation of the QoE parameter is a very interesting research area. Quality of Experience is a broad issue and requires the analysis of many aspects not only graphical user interfaces but also, inter alia, Quality of Service and user ratings.
Artykuł
Dostęp ograniczony
A novel adaptive checkpointing method based on information obtained from workflow structure
(2016) Kail, Eszter; Kacsuk, Péter; Kozlovszky, Miklós
Scientific workflows are data- and compute-intensive, thus, they may run for days or even weeks on parallel and distributed infrastructures such as grids, supercomputers, and clouds. In these high-performance computing infrastructures, the number of failures that can arise during scientific-workflow enact- ment can be high, so the use of fault-tolerance techniques is unavoidable. The most-frequently used fault-tolerance technique is taking checkpoints from time to time, when failure is detected, the last consistent state is restored. One of the most-critical factors that has great impact on the effectiveness of the checkpointing method is the checkpointing interval. In this work, we propose a Static (Wsb) and an Adaptive (AWsb) Workflow Structure Based checkpointing algorithm. Our results showed that, compared to the optimal checkpointing strategy, the static algorithm may decrease the checkpointing overhead by as much as 33% without affecting the total processing time of workflow execution. The adaptive algorithm may further decrease this overhead while keeping the overall processing time at its necessary minimum.
Artykuł
Dostęp ograniczony
Statistical models to accelerate software development by means of iterative compilation
(2016) Kamińska, Agnieszka; Bielecki, Włodzimierz
Minimization of data-processing time and reduction of software-development time are important practical problems to be tackled by modern computer science. This paper presents the authors’ proposal of a family of statistical models for the estimation of program execution time, which is an approach focused on both of the above problems at the same time. The family consists of a general model and specific models and has been elaborated based on empirical data collected for pattern-program loops representing some arbitrarily selected features related to the program structure and the specificity of a program-execution environment. The paper presents steps to elaborate the aforementioned family as well as the results of the carried-out experimental research. The paper demonstrates how the elaborated models can be applied in iterative compilation for optimization purposes, allowing us to reduce the time of software development and produce code with minimal execution time.