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The impact of administrator working hours on the reliability of the Centre of Language Technology

Walkowiak T., Pol M.

Journal of Polish Safety and Reliability Association

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2017

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Vol. 8, No. 1

167--174

EN

The paper presents reliability analysis of CLARIN-PL Centre of Language Technology (CLT). The CLT is a Polish part of the language technology infrastructure developed by CLARIN project. The main goal of which is to support researchers in humanities and social sciences. The infrastructure is a complex computer system that enables combining language tools with language resources into processing chains. Authors present the system structure, analyse types of faults and define the CLT reliability model. The model takes into account the fact the time gap, between the failure and the repair of the system is not exponential since repair actions are taken only when administrators are at work (assuming that administrators are not working 24/7). The model is used to estimate reliability metrics (mean time and 90th percentile of relative down time and relative partial operational time) by a use of Monte-Carlo simulation. Moreover, analysis of possible improvement in the CLT organisation and its influence on the estimated metrics is given.

2

A repair time model of a web based system including administrator working hours

Walkowiak T.

Journal of Polish Safety and Reliability Association

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2016

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Vol. 7, No. 1

233--240

EN

The paper presents a web based system reliability analysis. We propose to model different types of faults (hardware one, software and security incidents) taking consideration only the effect of the failure, not the source of the fault. It is assumed that failure events are independent and the time to failure is exponential. Whereas the time to repair is not exponential since repair actions are taken only when administrators are at work. We assume that administrators are not working 24/7. The paper presents an algorithmic model of the repair time including administrator working hours. The model is used to estimate reliability parameters (mean time, standard deviation and 90th percentile of yearly down time) by a use of Monte-Carlo simulation. The numerical results are compared with results from the analytical model (Markov one) that assumes exponential distribution of all repair times. Results for two web exemplar web systems (with reliability model consisting of two and five states) show the range of error caused by the exponential distribution assumption.

3

System tachografów cyfrowych - praktyczne aspekty wdrożenia

Nowacki G., Mitraszewska I., Kamiński T.

Transport Samochodowy

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2006

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z. 3

55--76

PL

W artykule przedstawione zostały problemy dotyczące legislacji wspólnotowej związanej z systemem tachografów cyfrowych. Scharakteryzowano strukturę systemu w Unii Europejskiej oraz uwzględniono elementy polskie, na których spoczywają główne zadania w tym zakresie. Ponadto omówiono obowiązki przedsiębiorców i typy urządzeń do pobierania danych z tachografów i kart kierowców. Zwrócono także uwagę na aspekty związane z instalacją, kalibracją i sprawdzaniem tachografów cyfrowych oraz kontrolą czasu pracy kierowców.

EN

The paper refers to some problems of legislation of European Union on Digital Tachograph System. The structure of Digital Tachograph System was characterized, especially Polish elements which responsible for main tasks of system. Furthemore the tasks of Transport Company and type of register equipments to download and storage data from digital tachographs and Driver cards were stressed. The problems refer to installation, calibration and check of digital tachograph, driver and driving time were taken into consideration.