Wyniki wyszukiwania - Biblioteka Nauki

1

Distributed Timed Automata with Independently Evolving Clocks

100%

Akshay S. , Bollig B. , Gastin P. , Mukund M. , Kumar K. N.

Fundamenta Informaticae

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2014

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tom Vol. 130, nr 4

377--407

EN

We propose a model of distributed timed systems where each component is a timed automaton with a set of local clocks that evolve at a rate independent of the clocks of the other components. A clock can be read by any component in the system, but it can only be reset by the automaton it belongs to. There are two natural semantics for such systems. The universal semantics captures behaviors that hold under any choice of clock rates for the individual components. This is a natural choice when checking that a system always satisfies a positive specification. To check if a system avoids a negative specification, it is better to use the existential semantics—the set of behaviors that the system can possibly exhibit under some choice of clock rates. We show that the existential semantics always describes a regular set of behaviors. However, in the case of universal semantics, checking emptiness or universality turns out to be undecidable. As an alternative to the universal semantics, we propose a reactive semantics that allows us to check positive specifications and yet describes a regular set of behaviors.

2

Analysis of measurement uncertainty in distributed systems for power and energy measurement

100%

Wójtowicz S.

Przegląd Elektrotechniczny

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2003

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tom R. 79, nr 10

738-741

EN

An analysis of measurement uncertainty, in a distributed measurement system is conducted in which the system components communicate by means of a network. The measured quantity is the electric active power and energy in the controlled areas, determined as the sum of measurement results of power meters.

PL

Autor przedstawia analizę niepewności pomiaru w systemach rozproszonych przesyłu i dystrybucji energii elektrycznej. Wielkością mierzoną jest moc czynna i energia w sterowanych obszarach, określana jako suma wskazań przyrządów pomiarowych w niejednakowych chwilach czasowych.

3

Ewolucja technologii zarządzania dokumentami

80%

Bartoszek J.

Studia z Automatyki i Informatyki

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2004

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tom T. 28/29

7--14

PL

W artykule przedstawiono ewolucję zarządzania dokumentami w systemach WfMS w ostatnich kilku latach. Szczególną uwagę zwrócono na klasyczne systemy WfMS i zarządzanie dokumentami w rozproszonych systemach XML Spaces oraz Work Spaces.

EN

The paper presents the evolution in the document management during last few years. It is intended to draw attention to classical WfM Systems and to distributed, Web-based XMLSpaces and WorkSpaces.

4

Cost-efficient synthesis of multiprocessor heterogeneous systems

80%

Deniziak S.

Control and Cybernetics

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2004

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tom Vol. 33, no 2

341-355

EN

In this paper an algorithm for co-synthesis of distributed embedded systems is presented. The algorithm is based on iterative improvement heuristics, taking into consideration sophisticated modifications and possibilities of further improvements. Starting from the solution with the highest performance, architecture of the system is modified until it achieves the lowest cost. It has been observed that the algorithm presented has the capacity of getting out of the local minima. Experimental results showed high efficiency of the algorithm. Almost all results obtained with the help of the algorithm were significantly better than the results obtained with the help of Yen-Wolf algorithm presented in the literature.

5

Regional control problem for distributed bilinear systems: Approach and simulations

80%

Ztot K. , Zerrik E. H. , Bourray H.

International Journal of Applied Mathematics and Computer Science

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2011

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tom 21

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nr 3

499-508

EN

This paper investigates the regional control problem for infinite dimensional bilinear systems. We develop an approach that characterizes the optimal control and leads to a numerical algorithm. The obtained results are successfully illustrated by simulations.

6

On the relationships among four timed process algebras

80%

Corradini F. , D'Ortenzio D. , Inverardi P.

Fundamenta Informaticae

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1999

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tom Vol. 38, Nr 4

377-395

EN

In this paper we contrast (the core of) four well-known process algebras specifically enriched for the specification and verification of timed systems. The aim of this comparison is twofold. On one hand it permits to gain confidence on how time and time passing are modelled in the four different timed process algebras. On the other hand, it establishes conditions under which mappings from a calculus to another can be provided which preserve (strong bisimulation-based) behavioural equivalence.

7

Integracja jednolitych, konfigurowalnych modułów jako narzędzie do budowy rozproszonego systemu sterowania wytwarzaniem

80%

Zając J.

Pomiary Automatyka Robotyka

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2008

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tom R. 12, nr 2

111--122

PL

Jednym z najistotniejszych aspektów warunkujących rozwój systemów wytwarzania jest zastępowanie ich zamkniętych, dedykowanych podsystemów sterowania charakterystycznych dla elastycznego wytwarzania przez otwarte, rozproszone podsystemy stosowane w systemach wytwarzania nowej generacji. W pracy dokonano porównania cech systemów tradycyjnych i systemów nowej generacji. Omówiono etapy budowy modelu dyskretnego, zautomatyzowanego systemu wytwarzania. Przedstawiono dwa sposoby podjęcia do budowy jego podsystemu sterowania oraz zaprezentowano przykłady rozwiązań wykorzystujących integrację jednolitych, konfigurowalnych modułów do budowy podsystemu sterowania wytwarzaniem.

EN

Replacement of dedicated control subsystems characteristic of flexible manufacturing by open, distributed subsystems applied in next generation manufacturing is an essential aspect of manufacturing systems development. The paper presents a comparison of the features of classical control systems and next generation control systems. Moreover, a three-stage procedure of discrete, automated manufacturing systems modeling is shown. The paper presents also two approaches to design of manufacturing control subsystems and shows examples of solutions which take advantage of an integration of unified, configurable modules for building manufacturing control subsystem.

8

A Testing Environment for Distributed Systems

80%

Sztandarski M. , Sowa G. , Goetzen P. , Marchlewska A.

Journal of Applied Computer Science Methods

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2012

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tom Vol. 4 No. 1

45--62

EN

The article presents the basics of modern software testing theory. Testing automation and the integration of testing into code writing will be examined in detail, and concept of a testing environment for distributed systems will be introduced.

9

Tools for Distributed Systems Monitoring

80%

Kufel Ł.

Foundations of Computing and Decision Sciences

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2016

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tom Vol. 41, No. 4

237--260

EN

The management of distributed systems infrastructure requires dedicated set of tools. The one tool that helps visualize current operational state of all systems and notify when failure occurs is available within monitoring solution. This paper provides an overview of monitoring approaches for gathering data from distributed systems and what are the major factors to consider when choosing a monitoring solution. Finally we discuss the tools currently available on the market.

10

On-Demand Server Synchronization Protocols of Session Guarantees

80%

Piątkowski Ł. , Sobaniec M. , Sobański G. , Kalewski M.

Foundations of Computing and Decision Sciences

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2010

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tom Vol. 35, No. 4

307-324

EN

Session guarantees define required properties of a distributed system regarding consistency from the point of view of a single mobile client. Consistency protocols of session guarantees are composed of two elements: the first is aimed at providing safety (the guarantees), the second is aimed at providing liveness (data synchronization). This paper presents survey and correctness proofs of two new data server synchronization protocols, which solve main problems of earlier proposals.

11

Pozyskiwanie i udostępnianie informacji obrazowej w systemach rozproszonych

80%

Piszczek M. , Zagrajek P. , Ryniec R.

Zeszyty Naukowe Wydziału ETI Politechniki Gdańskiej. Technologie Informacyjne

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2010

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tom T. 19

47-52

PL

Współczesny rozwój techniki obrazowej oraz systemów teleinformatycznych umożliwia badania nad nowymi rozwiązaniami dla rozproszonych systemów informacyjnych. Realizowane przez zespół prace dotyczą w głównej mierze systemów zbierania i wizualizacji informacji obrazowych. Zastosowanie metadanych obrazowych w powiązaniu z klasycznymi systemami monitoringu, układami obrazowania panoramicznego a także technologią kadrowania przestrzenno-czasowego przyczynia się do istotnego wzrostu potencjału informacyjnego opracowań terrofotogrametrycznych. Koncepcja obiektowego podejścia do informacji obrazowej ułatwia implementację rozwiązań dla Systemu Obrazowania Informacji Przestrzennej (SOIP). Przedstawione w artykule zagadnienia, stanowią przegląd realizowanych prac nad szczegółowymi rozwiązaniami dedykowanymi dla SOIP.

EN

Modern progress in the imaging technique and teleinformatic systems enable study for new solutions for distributed inromation systems. Work realized by the team concentrate mainly on systems for acquire and visualization of imaging information. Putting imaging metadata into use with classical monitoring systems, panoramic imaging setups and technology of space-time framing cause significant enhancement of information potential of terrophotogrametric compilations. Conception of object relation to imaging information facilitate implementation of solutions for System for Spatial Information Imaging (SSII). Issues presented in this paper are overview of realized work for particular solutions dedicated for SSII.

12

Simple distributed system hardware platform for basic research

80%

Krzywicki K. , Andrzejewski G.

Measurement Automation Monitoring

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2015

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tom Vol. 61, No. 2

47--50

EN

This paper presents the simple distributed system hardware platform for basic research. It allows to study the different variants and aspects of the data exchange or synchronization methods in distributed systems. Moreover, the platform has the ability to implement distributed embedded systems. The modularity of a system allows for fast reconfiguration of the platform, such as the exchange of end modules. Therefore, it is possible to make quick changes and verify the system operation.

13

Weak and exact domination in distributed systems

80%

Afifi L. , Magri E. M. , El Jai A.

International Journal of Applied Mathematics and Computer Science

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2010

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tom 20

|

nr 3

419-426

EN

In this work, we introduce and examine the notion of domination for a class of linear distributed systems. This consists in studying the possibility to make a comparison between input or output operators. We give the main algebraic properties of such relations, as well as characterizations of exact and weak domination. We also study the case of actuators, and various situations are examined. Applications and illustrative examples are also given. By duality, we extend this study to observed systems. We obtain similar results and properties, and the case of sensors is equally examined.

14

Minimization of the total completion time for asynchronous transmission in a packet data-transmission system

80%

Piórkowski A. , Werewka J.

International Journal of Applied Mathematics and Computer Science

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2010

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tom 20

|

nr 2

391-400

EN

The minimization of the total completion time for asynchronous transmission in distributed systems is discussed. Attention is focused on the problem of message scheduling on part of the sender. Messages to be sent form a queue, and the order in which they are to be sent has to be first established. The methods of scheduling messages, which minimize the factor of the total completion time, are presented herein. The message-scheduling problem becomes considerably complicated when the stream of data transmitted between the sender and the receiver is organized into packets. A scheduling rule, according to which the shortest messages (SPT-Shortest Processing Time) are selected as the first to be sent, has been proven to be appropriate for the proposed model. A heuristic algorithm for scheduling messages with real-time constraints is proposed. The performance of the scheduling algorithm is experimentally evaluated. The results of the study show the possibility of improving the total completion time from a few to ten percent, depending on the characteristics of the sender. Thus, the practicability of the method has been proved.

15

Local Verification Using a Distributed State Space

80%

Abid C. A. , Zouari B.

Fundamenta Informaticae

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2013

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tom Vol. 125, nr 1

1--20

EN

This paper deals with the modular analysis of distributed concurrent systems modelled by Petri nets. The main analysis techniques of such systems suffer from the well-known problem of the combinatory explosion of state space. In order to cope with this problem, we use a modular representation of the state space instead of the ordinary one. The modular representation, namely modular state space, is much smaller than the ordinary state space. We propose to distribute the modular state space on every machine associated with one module. We enhance the modularity of the verification of some local properties of any module by limiting it to the exploration of local and some global information. Once the construction of the distributed state space is performed, there is no communication between modules during the verification.

16

Security aspects in resource management systems in distributed computing environments

80%

Adamski M. , Kurowski K. , Mika M. , Piątek W. , Węglarz J.

Foundations of Computing and Decision Sciences

|

2017

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tom Vol. 42, No. 4

299--313

EN

In many distributed computing systems, aspects related to security are getting more and more relevant. Security is ubiquitous and could not be treated as a separated problem or a challenge. In our opinion it should be considered in the context of resource management in distributed computing environments like Grids and Clouds, e.g. scheduled computations can be much delayed because of cyber-attacks, inefficient infrastructure or users valuable and sensitive data can be stolen even in the process of correct computation. To prevent such cases there is a need to introduce new evaluation metrics for resource management that will represent the level of security of computing resources and more broadly distributed computing infrastructures. In our approach, we have introduced a new metric called reputation, which simply determines the level of reliability of computing resources from the security perspective and could be taken into account during scheduling procedures. The new reputation metric is based on various relevant parameters regarding cyber-attacks (also energy attacks), administrative activities such as security updates, bug fixes and security patches. Moreover, we have conducted various computational experiments within the Grid Scheduling Simulator environment (GSSIM) inspired by real application scenarios. Finally, our experimental studies of new resource management approaches taking into account critical security aspects are also discussed in this paper.

17

Asynchronous distributed state estimation for continuous-time stochastic processes

80%

Kowalczuk Z. , Domżalski M.

International Journal of Applied Mathematics and Computer Science

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2013

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tom 23

|

nr 2

327-339

EN

The problem of state estimation of a continuous-time stochastic process using an Asynchronous Distributed multi-sensor Estimation (ADE) system is considered. The state of a process of interest is estimated by a group of local estimators constituting the proposed ADE system. Each estimator is based, e.g., on a Kalman filter and performs single sensor filtration and fusion of its local results with the results from other/remote processors to compute possibly the best state estimates. In performing data fusion, however, two important issues need to be addressed namely, the problem of asynchronism of local processors and the issue of unknown correlation between asynchronous data in local processors. Both the problems, along with their solutions, are investigated in this paper. Possible applications and effectiveness of the proposed ADE approach are illustrated by simulated experiments, including a non-complete connection graph of such a distributed estimation system.

18

Distributed hard real-time systems : notions and performance measures

80%

Martyna J.

Zeszyty Naukowe Uniwersytetu Jagiellońskiego. Prace Informatyczne

|

1998

|

tom z. 8

29-44

EN

This paper surveys the state of art in quantification of hard real-time distributed systems. It introduces some new performance measures used in real-time computing and identifies key issues in the design and analysis of these systems. This paper outlines also typical requirements facing designers of safety critical hard real-time systems.

19

Distributed hard real-time system project

80%

Martyna J.

Zeszyty Naukowe Uniwersytetu Jagiellońskiego. Prace Informatyczne

|

1999

|

tom z. 9

21-31

EN

An architecture of a distributed system for time-constrained enviroments is presented. Hardware fault tolerance of this system is attained by the duplication of some elements of computer systems. Data replications, loose coupling, an automated restart capability and some functions resident on a system supervisor node provide the architecture software fault tolerant.

20

Reasoning on the Efficiency of Distributed Complex Event Processing

80%

Akili S. , Weidlich M.

Fundamenta Informaticae

|

2021

|

tom Vol. 179, nr 2

113--134

EN

Complex event processing (CEP) evaluates queries over streams of event data to detect situations of interest. If the event data are produced by geographically distributed sources, CEP may exploit in-network processing that distributes the evaluation of a query among the nodes of a network. To this end, a query is modularized and individual query operators are assigned to nodes, especially those that act as data sources. Existing solutions for such operator placement, however, are limited in that they assume all query results to be gathered at one designated node, commonly referred to as a sink. Hence, existing techniques postulate a hierarchical structure of the network that generates and processes the event data. This largely neglects the optimisation potential that stems from truly decentralised query evaluation with potentially many sinks. To address this gap, in this paper, we propose Multi-Sink Evaluation (MuSE) graphs as a formal computational model to evaluate common CEP queries in a decentralised manner. We further prove the completeness of query evaluation under this model. Striving for distributed CEP that can scale to large volumes of high-frequency event streams, we show how to reason on the network costs induced by distributed query evaluation and prune inefficient query execution plans. As such, our work lays the foundation for distributed CEP that is both, sound and efficient.