Wyniki wyszukiwania - Biblioteka Nauki

1

Reliability control of means of transport

100%

Okulewicz J. , Salamonowicz T.

Journal of KONBiN

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2006

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tom No. 2

299--305

EN

A method of means of transport maintenance with a requisite reliability is presented in this paper. Results are achieved by using redundancy of objects in a fleet and by making preventive replacement of objects’ elements. The acceptable level of a failure risk while executing transportation tasks has been taken as a criterion. Algorithm for selection of elements for preventive replacement has been developed and illustrated by an example.

2

On a class of limit reliability functions of some regular homogeneous series-parallel systems

100%

Kołowrocki K.

Matematyka Stosowana : matematyka dla społeczeństwa

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1993

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tom Nr 36

55--69

EN

In the investigation of large-scale systems the problem of the complexity of their reliability functions arises. This problem may be solved approximately by assuming that the number of system components tends to infinity and finding the limit reliability function. In this paper a four-element class of limit reliability functions for a regular homogeneous series-parallel system is presented. The number of series components of the system has the order of the logarithm of the number of its parallel components. The result is obtained under the assumption that the lifetimes of the particular components are independent and identically distributed random variables. The class presented is different from the known class of limit distributions of minimax statistics of independent random variables with the same distribution. Moreover, some examples of the systems considered and their limit reliability functions are given. The results can be useful in the investigation of the reliability of large systems.

3

Analysis of electromigration phenomenon in thick-film and LTCC structures at elevated temperature

80%

Nowak D. , Stafiniak A. , Dziedzic A.

Materials Science Poland

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2014

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tom Vol. 32, No. 2

247--251

EN

Studies on electromigration phenomenon in thick-film structures on alumina and LTCC substrates are presented in this paper. The effects of storage of Au and Ag electrode patterns in temperature range up to 300 °C under voltage bias were examined. The leakage characteristics of electrodes with 100 μm spacing at 50 V dc bias as a function of time and temperature are presented and analyzed. Scanning electron microscope (SEM) equipped with the energy-dispersive X-ray spectroscopy (EDX) detector was applied for determination of metal ions transport. Test structures with Au-based conductive material are much more resistant to electromigration than Ag-based layers.

4

Uwarunkowania eksploatacyjnej niezawodności parku maszynowego.

80%

Łunarski J. , Antosz K.

Technologia i Automatyzacja Montażu

|

2003

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tom nr 2

27-29

5

Reliability study of a containment shell

80%

Postek E. , Siemaszko A. , Kleiber M.

Journal of Theoretical and Applied Mechanics

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2002

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tom Vol. 40 nr 1

179-203

EN

Computational time needed for reliability analysis of realistic structural problems as a rule is very high. Improvements in efficiency are critical to allow solution of large realistic problems. The reliability analysis is usually performed using approximate First Order Reliability Method (FORM). Iterative solution procedures of FORM require extensive design sensitivity computations of high accuracy. The design of realistic structures requires computer-based numerical procedures, such as finite e,ement analysis. The design sensitivity gradients are not explicitly available in terms of design variables. The most intensive computational task of design sensitivity computation should be carried out by highly efficient and accurate methods such as discrete design sensitivity analysis. This paper describes requirements for design sensitivity information for reliability analysis. The way of coupling reliability computation with discrete AVM and DDM methods of design sensitivity analysis is pointed out. A computational program developed for layered concrete shells allows one to solve large realistic reliability problems. The reliability study of an RC nuclear containment shell is carried out. Reliability studies show which of the parameters have the highest impact on the reliability of the vessel.

PL

Analiza niezawodności dużych konstrukcji wymaga zazwyczaj bardzo długich obliczeń komputerowych. Poprawa efektywności algorytmów jest zazwyczaj warunkiem koniecznym uzyskania rozwiązań dla dużych rzeczywistych problemów. Analizę niezawodności zwykle przeprowadza się stosując przybliżoną metodę analizy niezawodności pierwszego rzędu (FORM). Procedury iteracyjne analizy niezawodności pierwszego rzędu (FORM) wymagają obliczenia gradientów wrażliwości o wysokiej dokładności. Projektowanie konstrukcji wymaga stosowania metod numerycznych takich jak metoda elementów skończonych. Gradienty wrażliwości nie są jawnie zależne od zmiennych projektowych. Obliczenia gradientów wrażliwości powinno być realizowane przy zastosowaniu efektywnych, dyskretnych metod analizy wrażliwości. W artykule przedstawiono sposób połączenia analizy niezawodności z dyskretnymi metodami obliczania gradientów wrażliwości - zmiennej sprzężonej (AVM) i różniczkowania bezpośredniego (DDM). Rozwinięty program komputerowy dla żelbetowych powłok warstwowych pozwala na rozwiązywanie dużych zadań niezawodnościowych. Przedstawiona została analiza niezawodności żelbetowego budynku bezpieczeństwa reaktora nuklearnego. Analiza niezawodności pozwala na stwierdzenie, który z parametrów projektowych ma największy wpływ na niezawodność osłony.

6

Niezawodność polskich samolotów bezpilotowych

80%

Krawczyk M.

Prace Instytutu Lotnictwa

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2012

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tom Nr 3 (224)

52--62

PL

W pracy wyznaczono niezbędną niezawodności kilku opracowanych w Polsce samolotów bezpilotowych, której osiągnięcie umożliwia ich eksploatacje w połączonej przestrzeni powietrznej. Obliczenia prowadzone były wg modelu katastrofy powietrznej oraz modelu pozwalającego na oszacowanie liczby ofiar na skutek rozbicia się samolotu. Podane przykłady pozwalają na sprecyzowanie Warunków Taktyczno-Technicznych, w szczególności dotyczących obszaru eksploatacji tychże samolotów.

EN

In this paper the level of reliability was estimated for several Unmanned Aerial Vehicles developed in Poland, that is necessary to enable these aircrafts to operate within the Single European Sky. Calculations were carried out based on air crash model as well as on the model capable to estimate the number of victims caused by the crash of an aircraft. Presented examples led to specification of the Tactical - Technical Conditions, in particular to determine the area of operation for aforementioned aircrafts.

7

Operational quality of a truck in expert's assessment

80%

Dmowski A. , Ignaciuk P. , Dębicka E. , Niewczas A. , Glavic D. , Matijošius J.

Archiwum Motoryzacji

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2019

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tom Vol. 83, nr 1

87--101

EN

The article presents the results of expert assessment of the quality of three different branches of trucks in terms of their suitability for long-term rental. The expert assessment is faster and cheaper compared to the analogous evaluation obtained on the basis of operational tests, hence the purpose of this article is to assess the accuracy of the results obtained in expert studies. The reliability characteristics of vehicles, such as: readiness, probability of first failure and distribution of mileage between successive repairs, were used as parameters for empirical quality assessment. Operational tests covered three groups of 30 vehicles. As part of the research, changes in vehicle technical readiness occurring during operation were also assessed. The failures of individual functional systems of the vehicle were also analyzed and compared with the results of expert studies. The expert assessment was based on a questionnaire regarding the overall assessment of the reliability and performance of cars. 32 experts - appraisers, with good knowledge of the construction of cars of the tested brands participated in these studies. On the basis of comparisons of the results of the expert assessment with the results of empirical studies, conclusions were drawn regarding the correctness of the assessment made by experts.

8

Monte Carlo method for reliability of parallel system with dependent failures of component

80%

Grabski F.

Journal of Polish Safety and Reliability Association

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2016

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tom Vol. 7, No. 1

67--72

EN

A problem of parallel system reliability with dependent failures of components is presented in the paper. It is assumed that lifetimes of components are independent random variable having Weibull distribution. We take under consideration a parallel (in reliability meaning) system consisting of n independent at the beginning of work and identical components. We assume that a load of the working system affects on the reliability of its components and the load of the system is distributed on all working components. Therefore, a failure rate of each component is changeable during run of the system and depends on a number of working elements at this point in time. As a model of the system failures we construct a stochastic process which value at the moment t denotes the number of working components. Generally it is neither Markov nor semi-Markov process. To assess the reliability characteristics of the system we simulate this stochastic process using the Monte-Carlo method and we calculate values of nonparametric kernel density and reliability functions estimators.

9

Introduction to Reliability Tests of Unmanned Aircraft Used in the Armed Forces of the Republic of Poland

80%

Michalska A.

Safety & Defense

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2019

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tom 5

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nr 2

54-61

EN

The paper is a theoretical introduction to the reliability tests of unmanned aerial vehicles used in the Polish armed forces. The purpose of the article is to determine the type/model of the unmanned aircraft in the service in the Polish Armed Forces, which results from the conducted reliability tests will be the basis for generalizing them to the largest group for the subsequent research. In order to achieve the assumed goal, the author, first, reviewed the terms and definitions describing the subject of the study. The trends occurring in the description of the examined subject-matter were recognized. Then, the typologies and classifications of unmanned aerial vehicles were analyzed on the basis of Polish and international sources, as well as normative documents. The last part of the paper comprises of a comparison of tactical and technical data of unmanned aerial vehicles used by the Polish Armed Forces.

10

A general concept of design procedure for floating docks regarding their reliability, safety and ecological aspects

80%

Girtler J.

Polish Maritime Research

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2005

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tom S 1

30-33

EN

In this paper is presented a concept of design procedure, and problems resulting from it, for floating docks with a view of taking into account their reliability and operational safety. It has been stressed that such design procedure is necessary for ensuring the docks appropriate pro-ecological features. It has been also shown that the design procedure should have several stages. The following kinds of design stages have been proposed to be accounted for : offer (canvassing) design, contract (ordered) design, concept (study) design, preliminary design, technical (classification) design and working design as well as the stage of elaboration of technical operational (delivery-acceptance) documentation. Knowledge areas necessary for such design procedure have been indicated. Attention has been also drawn to the necessity of accounting for, in designing the floating docks, diagnostic systems suitable to aid operational decision making .

11

An optimal preventive maintenance policy of parallel-series systems

80%

Duarte J. C. , Craveiro J. T. , Trigo T. P.

Journal of Polish Safety and Reliability Association

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2013

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tom Vol. 4, No. 1

29--34

EN

This paper presents an algorithm to solve the problem of maintenance management of a two state parallel-series system based on preventive maintenance over the different system components. It is assumed that all components of the system exhibit Weibull hazard function and constant repair rate and that preventive maintenance would bring the system to the as good as new condition. The algorithm calculates the interval of time between preventive maintenance tasks for each component, minimizing the costs, and in such a way that the total downtime, in a certain period of time, does not exceed a predetermined value. It is presented an industrial case study where the algorithm is applied.

12

Miary niezawodnościwej i strukturalnej istotności elementów

80%

Załęska-Fornal A.

Zeszyty Naukowe Akademii Marynarki Wojennej

|

2006

|

tom R. 47 nr 3 (166)

137-150

PL

W artykule zdefiniowano i wyznaczono strukturalną i niezawodnościową istotność elementów dla obiektów o różnych strukturach niezawodnościowych. Zdefiniowano także istotność zdarzeń bazowych w drzewach zdarzeń (uszkodzeń).

EN

The paper defines and determines the structural importance of the components for the systems of various structures. It also defines the reliability importance of the components for some structures of systems and the event tree importance of the basic events. Some illustrating examples are presented.

13

Reliability of sewage treatment plants processing sewage from school buildings located in non-urban areas

80%

Bugajski P. , Almeida M. A. A. , Kurek K.

Infrastruktura i Ekologia Terenów Wiejskich

|

2016

|

tom nr IV/3

1547--1557

EN

The aim of this study was to assess the reliability of two on-site sewage treatment facilities (BCT S-12 and TJ EP-4) serving two school buildings located in rural communes in Małopolska region. The reliability was determined using Weibull reliability method. The research was conducted for 24 months and it involved the collection and analysis of 48 samples of raw and treated sewage from each facility. The analyses included organic and biogenic pollution, i.e. BOD5 , COD, and total nitrogen. Reliability assessment revealed the following effectiveness for BCT S-12 facility: 77% for BOD5 , 96% for COD and 25% for total nitrogen. For TJ EP-4 facility, the effectiveness was 81%, 88% and 72% for BOD5 , COD and total nitrogen, respectively. Both facilities used the activated sludge process and experienced periodic disturbances in the treatment flow that resulted in reduced sewage treatment efficiency. Considering the above, the processes of nitrification and denitrification in the biological reactor should be streamlined to provide more effective removal of organic and nitrogen-based compounds in the investigated facilities.

14

Modelling ship’s diesel electrical system using Markov theory

80%

Mennis E. , Dagkinis I. , Nikitas N. , Platis A.

Journal of Polish Safety and Reliability Association

|

2008

|

tom Vol. 2

241--245

EN

One of the most critical systems for a ship operation is the diesel generator set. This is why the ship preserves four different diesel generators except the power battery packs. The paper describes the generator operation and the main failure conditions. Assuming that the failure rate of the system parts is constant the paper shows how the diesel generator system could be modelled in the context of Markov theory.

15

Surprises : The warranty, the reliability, and the systemability

80%

Pham H.

Journal of Polish Safety and Reliability Association

|

2008

|

tom Vol. 2

299

EN

In the fast growing, competitive global market and dynamic environments, we not only depend upon the continued functioning of a wide array of complex machinery and equipment of our everyday safety, security, mobility and economic welfare but also expect our electric appliances, automobile, transportation stations and data exchange systems to perform and perform well wherever and whenever we need them in order to survive. Such expectation is seldom realistic since it eventually breaks down, particularly when the system (or product) nowadays is operating in a complex random operating environment. Strong warranties are becoming more useful tactics for developers to attract potential customers especially due to the slowing economy. This talk discusses the research challenges and trends, and the reflections of the perception between the warranty, the reliability and the systemability.

16

Comparison of approaches to reliability verification of existing steel structures

80%

Nadolski V. , Holický M. , Sykora M. , Tur V.

Budownictwo i Architektura

|

2022

|

tom Vol. 21, no 4

13--24

EN

Many existing steel structures are exposed to degradation due to corrosion or fatigue and to increasing loads. Their reliability assessment is then needed. The key question is whether a particular structure can be preserved ‘as it is’, or needs to be strengthened, or whether it needs to be replaced. Unnecessary replacements of existing structures may be avoided and the remaining service life of existing steel structures may be authorized by: using advanced reliability verification techniques, optimizing target reliability, and obtaining data for a specific site or structure. In this contribution, the application of advanced reliability approaches is illustrated by the assessment of an existing steel structure. The case study demonstrates that such approaches may significantly improve assessment and allow to increase the load-bearing capacity of the structure (in the case under investigation by 10 to 20%). Improvements in reliability assessment are attributed to the use of an optimal target reliability level, case-specific statistical parameters and probabilistic distributions of the basic variables, and adjusted partial factors.

17

Semi-Markov processes: application in system reliability and maintenance

80%

Grabski F.

Journal of Polish Safety and Reliability Association

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2014

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tom Vol. 5, No. 1

57--62

EN

The author’s monograph “Semi-Markov Processes: Application in System Reliability and Maintenance” which will be published by Elsevier in 2014 is presented. The paper is composed of an introduction, the monograph contents, conclusions and the references the monograph contents is based on.

18

A Validation of Emotional Contagion Scale on the Indian Youth

80%

Agarwal S. P. , Gawali G. , Puranik D.

The New Educational Review

|

2022

|

tom 70

159-170

EN

The Emotional Contagion Scale (ECS) developed by Dr. Elaine Hatfield, is a self-report measure used to investigate the individual’s susceptibility to catch another person’s emotions and experience the same. The catching of emotions could be conscious or unconscious. The study aims to validate the Emotional Contagion scale on the Indian subcontinent population for future use and application. The original American scale consisted of 15 items to be responded to by selecting the suitable option from given five, was given to an Indian sample of 498 individuals. To check the validity, Confirmatory Factor Analysis (CFA) was performed. Gender differences were assessed and it was observed that men were high on catching and experiencing the emotions of others as compared to women. The Indian sample on ECS shows moderate to high reliability and high content validity. It thus concludes that the Emotional Contagion scale is valid for future use on the Indian Population.

19

Reliability and maintainability and REMM model

80%

Lewitowicz J.

Journal of KONBiN

|

2006

|

tom No. 2

141--144

EN

The Reliability Enhancement Methodology and Modeling (REMM) can provide alternative metrics from those traditionally used in the engineering community. This problem have outline the metrics available from such techniques and compares them with the more commonly used engineering metrics such as removal rate: MTTF, MTBF, MMFH, MTTR, MTBT, MTBCD.

20

Bezpieczeństwo i niezawodność systemów wbudowanych opartych na nowoczesnych mikrokontrolerach

80%

Szymczyk M. , Szymczyk P.

Automatyka / Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie

|

2011

|

tom T. 15, z. 2

443-449

PL

Nowoczesne mikroprocesory wykonywane są przy użyciu technologii CMOS o coraz większej skali integracji, co sprzyja powstawaniu błędów przejściowych, błędów stałych, defektów w procesie produkcji. Wprowadzenie mechanizmów mających na celu zwiększenie ich niezawodności staje się ważnym problemem nawet dla procesorów ogólnego przeznaczenia. W ciągu kilku dziesięcioleci opracowano różne metody zwiększające niezawodność układów elektronicznych, jak kody parzystości, redundancję sprzętową czy też programową. W artykule skupiono się na redundancji wykonania wątków przez nowoczesny procesor superskalarny jedno lub wielordzeniowy (posiadający możliwość wykonywania instrukcji z wielu wątków w czasie jednego cyklu zegarowego).

EN

Modern CMOS microprocessors produced in a great scale of integrity are vulnerable to transient hardware faults, hard faults and defects in production. Implementation of special mechanisms to improve reliability is a key of challenge also in microprocessors of general usage. Through decades different methods to improve reliability were designed such as parity code, hardware and software redundancy. In this article main focus is on redundant thread execution on modern superscalar processor (with possibility execution of different threads in one cycle of clock).