Numer czasopisma
Computer Science
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ISSN: 1508-2806
e-ISSN:
Data wydania
2014
Rocznik
Vol. 15
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. 15 (2014)
Artykuły numeru (rel.)
Artykuł
Dostęp ograniczony
Efficient implementation of branch-and-bound method on desktop grids
(2014) Tian, Bo Ye; Posypkin, Mihail Anatol'evič
The Berkeley Open Infrastructure for Network Computing (BOINC) is an open-source middleware system for volunteer and desktop grid computing. In this paper, we propose BNBTEST, a BOINC version of the distributed branch-and-bound method. The crucial issues of the distributed branch-and-bound method are traversing the search tree and loading the balance. We developed a subtask packaging method and three different subtask distribution strategies to solve these.
Artykuł
Dostęp ograniczony
Network management services based on the OpenFlow environment
(2014) Wilk, Paweł; Nawrocki, Piotr
The subject of this article is network management through web service calls, which allows software applications to exert an influence on network traffic. In this manner, software can make independent decisions concerning the direction of requests so that they can be served as soon as possible. This is important because only proper cooperation including all architecture layers can ensure the best performance, especially when software that largely depends on computer networks and utilizes them heavily is involved. To demonstrate that the approach described above is feasible and can be useful at the same time, this article presents a switch-level load balancer developed using OpenFlow. Client software communicates with the balancer through REST web service calls, which are used to provide information on current machine load and its ability to serve incoming requests. The result is a cheap, highly customizable and extremely fast load balancer with considerable potential for further development.
Artykuł
Dostęp ograniczony
A workflow-oriented approach to Propagation Models in Heliophysics
(2014) Pierantoni, Gabriele; Carley, Eoin P; Byrne, Jason P; Pérez-Suárez, David; Gallagher, Peter T
The Sun is responsible for the eruption of billions of tons of plasma and the generation of near light-speed particles that propagate throughout the solar system and beyond. If directed towards Earth, these events can be damaging to our tecnological infrastructure. Hence there is an effort to understand the cause of the eruptive events and how they propagate from Sun to Earth. However, the physics governing their propagation is not well understood, so there is a need to develop a theoretical description of their propagation, known as a Propagation Model, in order to predict when they may impact Earth. It is often difficult to define a single propagation model that correctly describes the physics of solar eruptive events, and even more difficult to implement models capable of catering for all these complexities and to validate them using real observational data. In this paper, we envisage that workflows offer both a theoretical and practical framework for a novel approach to propagation models. We define a mathematical framework that aims at encompassing the different modalities with which workflows can be used, and provide a set of generic building blocks written in the TAVERNA workflow language that users can use to build their own propagation models. Finally we test both the theoretical model and the composite building blocks of the workflow with a real Science Use Case that was discussed during the 4th CDAW (Coordinated Data Analysis Workshop) event held by the HELIO project. We show that generic workflow building blocks can be used to construct a propagation model that succesfully describes the transit of solar eruptive events toward Earth and predict a correct Earth-impact time.
Artykuł
Dostęp ograniczony
Turing machine approach to runtime software adaptation
(2014) Rudy, Jarosław
In this paper, the problem of applying changes to software at runtime is considered. The computability theory is used in order to develop a more general and programming-language-independent model of computation with support for runtime changes. Various types of runtime changes were defined in terms of computable functions and Turing machines. The properties of such functions and machines were used to prove that arbitrary runtime changes on Turing machines are impossible in general cases. A method of Turing machine decomposition into subtasks was presented and runtime changes were defined through transformations of the subtask graph. Requirements for the possible changes were considered with regard to the possibility of subtask execution during such changes. Finally, a runtime change model of computation was defined by extension of the Universal Turing Machine.
Artykuł
Dostęp ograniczony
Network resilience analysis - review of concepts and a country level case study
(2014) Kamola, Mariusz; Arabas, Piotr Przemysław
This paper presents the rationale behind performing an analysis of Internet resilience in the sense of maintaining a connection of autonomous systems in the presence of failures or attacks - on a level of a single country. Next, the graph of a network is constructed that represents interconnections between autonomous systems. The connectivity of the graph is examined for cases of link or node failure. Resilience metrics are proposed, focusing on a single autonomous system or on overall network reliability. The process of geographic location of networking infrastructure is presented, leading to an analysis of network resilience in the case of a joint failure of neighboring autonomous systems.
Artykuł
Dostęp ograniczony
An algorithm of semi-Delaunay triangulation of points cloud scattered on a surface
(2014) Kucwaj, Jan
The purpose of this paper is to generalize the Delaunay[13] triangulation onto surfaces. A formal definition and an appropriate algorithm are presented. Starting from a plane domain Delaunay triangulation definition, a theoretical approach is evolved (which is a background for further considerations). It has been proven that, in the case of a plane surface, the introduced Delaunay triangulation of surfaces is identical to classical Delaunay triangulation of the plane domain. The proposed algorithm is implemented and numerical results are shown.