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Wyświetlanie 1-15 z 88
Tytuł:
Batch scheduling of deteriorating products
Autorzy:
Barketau, M. S.
Cheng, T. C. E.
Kovalyov, M. Y.
Ng, C. T. D.
Powiązania:
https://bibliotekanauki.pl/articles/375908.pdf
Data publikacji:
2007
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
scheduling
batching
remanufacturing
deterioration
Opis:
In this paper we consider the problem of scheduling N jobs on a single machine, where the jobs are processed in batches and the processing time of each job is a simple linear increasing function depending on job's waiting time, which is the time between the start of the processing of the batch to which the job belongs and the start of the processing of the job. Each batch starts from the setup time S. Jobs which are assigned to the batch are being prepared for the processing during time S0 < S. After this preparation they are ready to be processed one by one. The non-negative number bi is associated with job i. The processing time of the i-th job is equal to bi(si - (si(b) + S0)), where si(b) and si are the starting time of the b-th batch to which the i-th job belongs and the starting time of this job, respectively. The objective is to minimize the completion time of the last job. We show that the problem is NP-hard. After that we present an O(N) time algorithm solving the problem optimally for the case bi = b. We further present an O(N2) time approximation algorithm with a performance guarantee 2.
Źródło:
Decision Making in Manufacturing and Services; 2007, 1, 1-2; 25-34
1896-8325
2300-7087
Pojawia się w:
Decision Making in Manufacturing and Services
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Probabilistic models for analyzing the availability and profit of a deteriorating 2-out-of-4 system
Autorzy:
Yusuf, I.
Powiązania:
https://bibliotekanauki.pl/articles/406425.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
deterioration
linear consecutive
profit
availability
Opis:
This paper deals with modelling and evaluating the availability and profit of a linear consecutive 2-out-of-4 system exposed to three consecutive stages of deterioration before failure. The system will pass through three consecutive stages of deterioration: slow, medium and fast before failure. The failure and repair times are assumed to be exponentially distributed. Explicit expressions for the system avail-ability, the probability of a repairman being busy due to the failure of a unit, or due to the replacement of failed units, and the profit function have been derived using a probabilistic approach. The impacts of the failure and repair rate on system availability and profit have been investigated. The results of this paper will enhance system performance and ensure the timely execution of appropriate maintenance and improvement, and thus is a major tool for decision making, planning and optimisation.
Źródło:
Operations Research and Decisions; 2016, 26, 4; 91-100
2081-8858
2391-6060
Pojawia się w:
Operations Research and Decisions
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mineralogical and geochemical studies of secondary mineral assemblages related to deterioration of building materials
Autorzy:
Marszałek, Mariola
Dudek, Krzysztof
Gaweł, Adam
Czerny, Jerzy
Powiązania:
https://bibliotekanauki.pl/articles/2058620.pdf
Data publikacji:
2019
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
stone deterioration
secondary salts
aphthitalite
darapskite
Opis:
The study was aimed at mineralogical and geochemical characteristics of secondary phases related to deterioration of historic building materials. The investigations, carried out in the Holy Trinity Basilica in Kraków, Poland, focused on the southern facade of the 17th-century Myszkowskis Chapel, built of the Miocene Pińczów limestone. Lower part of the facade is covered with a cement render, and the exposed foundations are made of Jurassic limestone and Cretaceous sandstone, both of local origin from the Kraków region and neighbouring Carpathians, in the form of irregular blocks bound with a cement mortar. The wall surface exhibits clear signs of damage; from dark grey soiling and scaling to efflorescences. Sampled materials, deteriorated, altered crusts and efflorescences were analysed with optical and scanning electron microscopy, X-ray diffraction, and Raman microspectroscopy methods. The secondary minerals distinguished include abundant gypsum CaSO42H2O, less common thenardite Na2SO4 (and/or mirabilite Na2SO410H2O), aphthitalite (K, Na)3Na(SO4)2, darapskite Na3(SO4)(NO3)H2O, ettringite Ca6Al2(SO4)3(OH)12 26H2O, monosulphite Ca4Al2O6SO311H2O, as well as scarce nitre KNO3, nitratine NaNO3 and halite NaCl. Gypsum usually forms surface crusts and fills the pores inside some materials. The efflorescences, sampled from the exposed foundations, consisted of thenardite and/or mirabilite, aphthitalite and darapskite, whereas ettringite and monosulphite were connected with cement renders. Traces of nitre, nitratine and halite were detected at various elements of the chapel facade and foundations. The origin of the salts is related to composition and physicochemical properties of the building materials, as well as to anthropogenic factors.
Źródło:
Geological Quarterly; 2019, 63, 4; 683--698
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ultrasonic waves and strength reduction indexes for the assessment of the advancement of deterioration processes in travertines from Pamukkale and Hierapolis (Turkey)
Autorzy:
Bobrowska, A.
Domonik, A.
Powiązania:
https://bibliotekanauki.pl/articles/178309.pdf
Data publikacji:
2015
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
travertine
deterioration
geomechanical properties
ultrasonic diagnosis
strength
Opis:
In constructions, the usefulness of modern technical diagnostics of stone as a raw material requires predicting the effects of long-term environmental impact of its qualities and geomechanical properties. The paper presents geomechanical research enabling presentation of the factors for strength loss of the stone and forecasting the rate of development of destructive phenomena on the stone structure on a long-time basis. As research material Turkish travertines were selected from the Denizli–Kaklık Basin (Pamukkale and Hierapolis quarries), which have been commonly used for centuries in global architecture. The rock material was subjected to testing of the impact of various environmental factors, as well as European standards recommended by the author of the research program. Their resistance to the crystallization of salts from aqueous solutions and the effects of SO2, as well as the effect of frost and high temperatures are presented. The studies allowed establishing the following quantitative indicators: the ultrasonic waves index (IVp) and the strength reduction index (IRc). Reflections on the assessment of deterioration effects indicate that the most active factors decreasing travertine resistance in the aging process include frost and sulphur dioxide (SO2). Their negative influence is particularly intense when the stone material is already strongly weathered.
Źródło:
Studia Geotechnica et Mechanica; 2015, 37, 3; 3-9
0137-6365
2083-831X
Pojawia się w:
Studia Geotechnica et Mechanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The influence of natural climatic factors on the geomechanical properties of siliceous limestones from kazimierz dolny (Poland)
Autorzy:
Pinińska, Joanna
Bobrowska, Alicja
Łukasiak, Dominik
Powiązania:
https://bibliotekanauki.pl/articles/2025358.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
opoka
Kazimierz Dolny
climatic factors
geomechanics
deterioration
Opis:
Based on the ex am ple opoka, stone ar chi tec ture of Kazimierz Dolny, mod ern re search meth ods were ap plied to an anal y sis of geomechanical qual i ties of this spe cial rock, se lected very ef fi ciently by me di eval, lo cal build ers. Ow ing to theirs skill and the qual i ties of the cho sen ma te rial, for ti fi ca tions, re li gious and res i den tial build ings have been preserved in good con di tion to the pres ent day. It was ana lysed what fac tors of the opoka ag ing are the most re spon si ble for their de struc tion re sis tance in the long time scale. The re sults of stud ies in di cate that opokas have an in creased ability to re duce the uni ax ial com pres sion strength due to the im pact of cy cling freez ing and ther mal shock. This ob ser vation shows that opokas are char ac ter ized by a high re sis tance to hu midity.
Źródło:
Studia Quaternaria; 2016, 33; 103-110
1641-5558
2300-0384
Pojawia się w:
Studia Quaternaria
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Reverse logistic model for deteriorating item with preservation technology investment and learning effect in an inflationary environment
Autorzy:
Singh, S. R.
Rathore, H.
Powiązania:
https://bibliotekanauki.pl/articles/205799.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
reverse logistics
deterioration
preservation technology
learning
inflation
Opis:
Recycling is essential for the existence of the environment. Nowadays, recycling is also being promoted by the governments of numerous countries in the world. In the recycling process, the used items are collected from the customers and sent back to the remanufacturing unit. In the literature, many authors have assumed that the remanufactured items are as good as the freshly produced ones, but this is not really practical. The remanufactured items are of lower quality than the freshly produced ones. For purposes of studying the recycling process we have developed a reverse logistic model for the deteriorating items. The deterioration rate is treated as a controllable variable, which is controlled by investing in preservation technology. The demand rate is taken as exponential function of time with demand dependent manufacturing and remanufacturing rates. The fresh products are sold in the primary market and the remanufactured products are sold in the secondary market at a low selling price, in view of the low quality of remanufactured products. The whole study is carried out under the effect of learning in an inflationary environment and the learning coefficients are associated with production cost and set-up cost. The main objective of this study is to find the optimal cost value and the optimal operating times. At the end of this article numerical illustration is presented and sensitivity analysis is performed. The whole of the mathematical calculations is done with the use of the mathematical software Mathematica7.
Źródło:
Control and Cybernetics; 2016, 45, 1; 83-94
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wpływ wybranych procesów niszczących na trwałość piaskowców godulskich z Brennej
The influence of the selected deterioration processes on durability of the Godula sandstones from Brenna
Autorzy:
Łukasiak, D.
Powiązania:
https://bibliotekanauki.pl/articles/170518.pdf
Data publikacji:
2013
Wydawca:
Poltegor-Instytut Instytut Górnictwa Odkrywkowego
Tematy:
Brenna
piaskowce godulskie
deterioracja
Godula sandstones
deterioration
Opis:
Artykuł podejmuje problematykę trwałości piaskowców godulskich z Brennej, które wykorzystywane są jako elementy konstrukcyjne w licznych obiektach budowlanych na terenie Europy. Tak szerokie wykorzystanie tego surowca skalnego wymusza ocenę jego odporności na działanie czynników niszczących w danych warunkach klimatycznych i funkcjonalnych. Pozwala to rozpoznać trwałość materiału skalnego w długiej skali czasowej oraz przeciwdziałać procesowi deterioracji, czyli pogarszaniu jakości i właściwości fizyko-mechanicznych danego surowca skalnego. Ocenę trwałości przeprowadzono na materiale pozyskanym z kamieniołomu Głębiec z dwóch stref rozpoznanego profilu wietrzeniowego. Były to piaskowce o charakterystycznym dla tego kamieniołomu, szaroniebieskim i szarozielonym zabarwieniu. W warunkach laboratoryjnych przeprowadzono modelowanie oddziaływania wybranych procesów niszczących na strukturę analizowanego materiału skalnego. Rozpoznano wpływ roztworów wodnych, zamrozu, krystalizacji soli oraz dwutlenku siarki. Dodatkowo podjęto próbę oceny odporności tego materiału na proces ścierania. Przeprowadzone badania pozwalają stwierdzić, iż eksploatacja analizowanych piaskowców powinna być prowadzona z selektywnym doborem ich przeznaczenia, gdyż charakteryzują się one zróżnicowaną odpornością na deteriorację, zależnie od stopnia zwietrzenia. Jednocześnie uwzględniać należy podatność analizowanego materiału skalnego na destrukcyjne działanie krystalizujących minerałów siarczanowych, co szczególnie widoczne jest w przypadku piaskowców szarozielonych. Powstałe w tym procesie spękania przebiegają najczęściej równolegle do powierzchni stropowej warstw piaskowców. Powyższe uwagi powinny być zatem uwzględniane podczas projektowania przeznaczenia badanych surowców skalnych jako elementów konstrukcyjnych, funkcjonujących w zmiennych warunkach geośrodowiskowych.
The article deals with durability problems of the Godula sandstones from Brenna, which are used as construction elements in numerous building objects in Europe. So extensive use of this rock material forces evaluation of its resistance to destructive factors under given climatic and functional conditions. This allows to recognize the durability of rock material in a long time scale as well as prevent the process of deterioration that worsens the quality and physio-mechanical properties of the given rock material. The durability evaluation was carried out on the material acquired from the quarry Głębiec, from two zones of recognized weathering profile. The sandstones had typical colors for this quarry – grey-blue and grey-green. The modeling of the influence of selected deterioration processes on the structure of the analyzed rock material was carried out under laboratory conditions. The influence of water solutions, frost, crystallization of salt and sulfur dioxide were recognized. In addition, attempts to assess the resistance of the material to the process of attrition were taken. The studies lead to a conclusion that the use of the analyzed sandstones should include selective choice of their destination, because they are characterized by variable resistance to deterioration depending on the weathering degree. At the same time the susceptibility of the analyzed rock material to destructive actions of crystallizing sulfate minerals should be taken into account, which is particularly evident in the case of grey-green sandstones. The cracks resulting from this process usually run parallel to the top tills’ surface of the sandstone layers. Therefore the abovementioned observations should be taken into account in the design of the destination of studied rock materials as construction elements, functioning under variable geo-environmental conditions.
Źródło:
Górnictwo Odkrywkowe; 2013, 54, 1; 56-61
0043-2075
Pojawia się w:
Górnictwo Odkrywkowe
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optimizing plants maintenance cost using strategic switching approach
Autorzy:
Kareem, B.
Powiązania:
https://bibliotekanauki.pl/articles/409124.pdf
Data publikacji:
2013
Wydawca:
Politechnika Poznańska. Wydawnictwo Politechniki Poznańskiej
Tematy:
maintenance
strategy
optimality
scheduling
deterioration
switching
plant
Opis:
Inadequate supply of public electricity in Nigeria has affected the productivity of many manufacturing industries. Electric generating plant is being used as a standby supplement to public electricity at outage hours. The high cost of running and maintenance of this generating plant has adversely affected the sustainability of the industry. A maintenance strategic switching approach was developed to minimize the cost of running the electric generating plant in the industries. Maintenance strategic switching and cost control parameters are preventive, repair/corrective and replacement. The maintenance cycle for each of the components served as tool for the determination of cumulative sum of maintenance cost from which the minimum cost schedule was selected. Data collected on power machinery from a water generating company was used to test the model. The least probability of failure (non-progressive deterioration) for components was recommended for adoption. There was a significant saving in maintenance cost of components under the non-progressive deterioration. In the 750 schedule, while the cost of maintenance with progressive deterioration was N149, 677, that of non-progressive, least failure probability was N75, 960.35 with savings of 49.25% over the former. Therefore, most economic schedule was 750 cycles. This scheme predicted for the organization the optimal maintenance strategy to utilize.
Źródło:
Research in Logistics & Production; 2013, 3, 3; 193-212
2083-4942
2083-4950
Pojawia się w:
Research in Logistics & Production
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The computer - aided analysis of images to assess condition of gas turbine blades
Autorzy:
Pawlak, W.
Błachnio, J.
Powiązania:
https://bibliotekanauki.pl/articles/243376.pdf
Data publikacji:
2013
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
gas turbine
blades
discoloration
deterioration of microstructure
Opis:
In order to guarantee reliable and safe operation of avionic turbo engine their components and subassemblies are subjected to regular inspections and maintenance. The most frequent reasons for failures of the engines include overheating of materials, thermal fatigue of blades and vanes in the jet subassembly as well as the gas turbine rotor. Failures of that type lead to faulty operation of the engine and sometimes to accidents with disastrous consequences. The decision to have the engine repaired is taken by maintenance personnel that chiefly employ the method of visual inspection with use of a videoscope. However, such examination of turbine components is burdened by a subjective approach. To improve reliability and trustworthiness of the examinations results it is necessary to enable objective and unbiased evaluation of examination results. This paper outlines a non-destructive method that is suitable for evaluation of condition demonstrated by gas turbine blades and is based on digital processing of images acquired from the blade surface in visible light. To enable high clearness of these images the particular attention is paid to the problem of how to provide optimum conditions for investigations and mitigate geometrical distortions of images acquired from maintenance operations. The paper demonstrates that there are relationships between operation lifetime of blades and discoloration of their surfaces due to overheating of the blade material. These relationships are revealed by digital analysis of images acquired for the blade surfaces and expressed as statistical parameter of the first and second order. To improve unambiguity of the analysis results a low-pass filter was applied. It was demonstrated that these relationships are suitable for evaluation how much the status of the blade material microstructure is altered. Results from this study enable formulation of the conclusion that diagnostics of gas turbine blades through computer-aided analysis of images acquired from the blade surfaces may even be possible under field conditions with no downtime of the equipment under tests.
Źródło:
Journal of KONES; 2013, 20, 3; 299-306
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
MOUNTING RESTLESSNESS: CHANGES IN ATTITUDES TO THE COVID-19 THREAT
Autorzy:
Markiewicz, Katarzyna
Powiązania:
https://bibliotekanauki.pl/articles/2138053.pdf
Data publikacji:
2021-07-26
Wydawca:
Fundacja Edukacji Medycznej, Promocji Zdrowia, Sztuki i Kultury Ars Medica
Tematy:
lockdown
stress
mood deterioration
neuropsychological intervention
relief
Opis:
Since the outbreak of the COVID-19 pandemic, many scientific papers have described the medical aspects and treatment of the virus infection and its symptoms. There are also many studies on how pandemics of this magnitude affect psychological wellbeing. Despite the spread of COVID-19, it has remained a rather abstract threat for many people in Poland. They have often expressed disbelief and negative attitudes toward social restrictions. The study aimed to investigate changes in attitudes to the COVID-19 threat in young people and the psychological repercussions of social isolation. The present study examined the changes in young people's attitudes, ones not directly affected by COVID19, over a period of a month. It comprised 41 individuals aged 21 to 60. The partic- ipants were asked to fill out a specially designed Internet questionnaire. This consisted of 5 open questions concerning their attitudes, values, feelings, reactions, and vision of the future. They were also encouraged to give their own remarks. At first, 46.6% of participants reported a feeling of discomfort, while 48.4% treated the situation as an opportunity to temporarily slow down the pace of life. However, negative moods and deterioration of mental state arose over time, and 58.7% of respondents reported discomfort in the second study. It shows that counter-arguing against information that causes discomfort and fear does not work for long. Moreover, the majority of them believed that the epidemic would result in the deterioration of their psychological wellbeing. The study revealed that psychological restlessness was almost imperceptible at first, and many participants reported a feeling of relief. Nevertheless, deterioration of mental state arose gradually, often leading to a lack of motivation, feelings of loneliness, helplessness, and, consequently, aggressive behaviors. The neuropsychological and biological aspects of long-term stress are also discussed.
Źródło:
Acta Neuropsychologica; 2021, 19(3); 307-318
1730-7503
2084-4298
Pojawia się w:
Acta Neuropsychologica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Badania ultradźwiękowe w ocenie deterioracji skał
Ultrasonic assessment of stonework elements deterioration
Autorzy:
Pinińska, J.
Bobrowska, A.
Pamukcu, C.
Powiązania:
https://bibliotekanauki.pl/articles/183683.pdf
Data publikacji:
2009
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
trawertyn
właściwości geomechaniczne
deterioracja
travertines
geomechanical properties
deterioration
Opis:
In an ageing process of stonework elements their strength and decoration value are changing. Ultrasonic method of nondestructive testing is especially applicable in determining the state of the art of rock deterioration and in forecasting and controlling further stages of changes. Tested were, alike, fresh rock samples and samples of deteriorated stoneworks from various locations, subjected to artificial ageing by cyclic freezing, saturating with salt solutions leading to fast drying and crystallizing of salts, and increasing of rock temperature. The poster shows results of comparable researches of ageing travertines from the Raciszyn quarry in Poland and from two locations in Hierapolis, Turkey.
Źródło:
Geologia / Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie; 2009, 35, 2/1; 633-639
0138-0974
Pojawia się w:
Geologia / Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Rola mikroorganizmów w deterioracji naturalnych kamieni budowlanych
Role of microorganisms in deterioration of natural building stones
Autorzy:
Cwalina, B.
Powiązania:
https://bibliotekanauki.pl/articles/318692.pdf
Data publikacji:
2003
Wydawca:
Polskie Towarzystwo Przeróbki Kopalin
Tematy:
mikroorganizmy
kamienie budowlane
deterioracja
microorganisms
deterioration
building stones
Opis:
Wielu autorów wykazało, że mikroorganizmy odgrywają istotną rolę we wszystkich zmianach występujących na powierzchni budynków i pomników wykonanych z naturalnych kamieni, włączając wielokolorowe plamy i osady tworzące skorupy. Przez długi czas były one wiązane z procesami fizykochemicznymi, będącymi skutkiem głównie czynników klimatycznych, zanieczyszczenia powietrza lub działalności konserwatorskiej. W niniejszej pracy opisano rolę mikroorganizmów w niszczeniu naturalnych kamieni budowlanych, włączając opis mechanizmów uczestniczących w tych procesach.
It has been demonstrated bay many authors that microorganisms play an important role in all alterations that occur on surface of buildings and monuments made of natural stones, including the multicoloured staining and crust-forming deposits. For a long time they were connected with physicochemical processes being a result mainly of climatic factors, air pollution or conservation activity. The role of microorganisms in deterioration of the natural building stones, including description of mechanisms involved in these processes has been described in this paper.
Źródło:
Inżynieria Mineralna; 2003, R. 4, nr 1, 1; 39-48
1640-4920
Pojawia się w:
Inżynieria Mineralna
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Deterioracja elewacji zewnętrznych wywołana biofilmem
Deterioration of the external façade caused by biofilm
Autorzy:
Piontek, M.
Lechów, H.
Powiązania:
https://bibliotekanauki.pl/articles/372334.pdf
Data publikacji:
2013
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
biofilm
deterioracja
elewacje zewnętrzne
biofilms
deterioration
external facades
Opis:
Zewnętrzne elewacje ulegają niszczeniu w wyniku obecności mikroorganizmów, które tworzą na nich czynną warstwę, określaną jako biofilm. Zjawisko prowadzi do zmian w strukturze materiału oraz obniżenia ich wartości użytkowej. Ochrona elewacji zewnętrznych polega na redukowaniu lub eliminowaniu czynników sprzyjających korozji biologicznej. Artykuł stanowi kompendium wiedzy na temat zjawiska deterioracji elewacji wywołanej czynnikami biologicznymi.
The external elevations are destroyed as a result of the presence of microorganisms that make them active layer known as a biofilm. This phenomenon leads to changes in the structure of the material and reduce their value. Privacy exteriors is reducing or eliminating factors that contribute to biological corrosion. The article is a compendium of knowledge about the phenomenon of deterioration elevation caused by biological factors.
Źródło:
Zeszyty Naukowe. Inżynieria Środowiska / Uniwersytet Zielonogórski; 2013, 151 (31); 77-85
1895-7323
Pojawia się w:
Zeszyty Naukowe. Inżynieria Środowiska / Uniwersytet Zielonogórski
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Simulation model and state analysis of ship transmission line
Autorzy:
Hu, Y.
Xu, M.
Li, Y.
Powiązania:
https://bibliotekanauki.pl/articles/259613.pdf
Data publikacji:
2018
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
ship power
transmission line
simulation model
insulation deterioration
Opis:
In order to discuss the simulation model of the ship transmission line and the state of the transmission line, an early fault model is built according to the evolution principle of the short circuit fault of the transmission line and combining with the fault characteristics of the early fault. A small distributed ship transmission line system is built in MATLAB/ Simulink. Then, combined with the constructed fault module, the original short circuit module, and the load module, the various states (normal state, early fault state, severe early fault state, short circuit state) of the ship transmission line are stimulated, and the features of voltage signal in each state is analysed. It is concluded that, due to the normal operation of the ship transmission line system, the variation characteristics of the flow signal and voltage signal caused by the sudden load mutation, that is, the sudden load and the sudden increase load, are very similar to the changes caused by the early fault. Therefore, in order to find a more accurate early fault detection method, the state is divided into normal state, sudden load state, sudden increase and sudden decrease load state.
Źródło:
Polish Maritime Research; 2018, S 3; 36-42
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Integrated Maintenance-Quality Strategies Taking into Account the Impact off the System Degradation on the Quality of Output Products
Autorzy:
Gouiaa-Mtiba, Amal
Dellagi, Sofiene
Achour, Zied
Erray, Walid
Powiązania:
https://bibliotekanauki.pl/articles/503750.pdf
Data publikacji:
2019
Wydawca:
Międzynarodowa Wyższa Szkoła Logistyki i Transportu
Tematy:
Integrated Maintenance strategy
reworking activity
deterioration
optimization
quality
Opis:
This paper deals with integrated models joining maintenance and quality. We consider a manufacturing system composed of a single machine subject to an increased random failure rate and producing conforming and non-conforming items. In order to decrease the random failure rate and its impact on the quality of output products, a bloc type preventive maintenance strategy with minimal repair is considered. Our study consists in developing integrated analytical models joining maintenance and quality in order to determine the optimal preventive maintenance plan taking into account the progressive quality perturbation and the economic impact of reworking activities. Two strategies are developed. In fact, for the first strategy, we propose reworking activities for all non-conforming products in order to improve their quality condition and to sell all batches at the best price Pmax. The aim of this strategy is to find the optimal number of batches produced and reworked N* before each preventive maintenance action, maximizing the total net profit per time unit PT1. For the second strategy, the same problem is studied but for a finite horizon. Two mathematical models are developed in order to find the optimal value of the decision variable N* for both strategies. Numerical examples are presented in order to illustrate the proposed models and a sensitivity study is developed to evaluate the influence of the variation of some parameters.
Źródło:
Logistics and Transport; 2019, 41, 1; 41-50
1734-2015
Pojawia się w:
Logistics and Transport
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 88

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