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Упит dcterms_subject_txt:availability

10 items

  • The optimization of auxiliary machinery in open-cast lignite mines: a case study of bulldozers

    Dragan Ignjatović, Predrag Jovančić, Stevan Đenadić, Ivan Janković, Ivica Ristović (2019)
    One of the most important prerequisites for the successful operation of the open-cast lignite mine is to carry out all the auxiliary works timely with the necessary quality. The most important and most commonly used auxiliary machines are bulldozers. Engaging time of bulldozers use is in direct relation with the coefficients of the time and capacity utilization of the continuous system for the excavation of coal and tailings, which indicates their importance. More than 100 bulldozers have been hired ...
    open-cast coal mine, auxiliary works, bulldozers, optimization, availability
    ... Optimal replacement те is established, based оп diagrams ог availability of these dozers (declining trend of technical availability coefficient of bulldozers in Kolubara basin for first ten years of operation) and limiting availability of 0.80. This diagram is shown in Figure 8 [1]. 12 3 1 0,97 ...
    ... Figure 7. Declining пепа ој technical availability coefficient ој БиПаогет САТ D8R тп Kolubara basin during ј1751 ten years of operation This diagram (Figure 7) is used for further analysis related to optimal replacement time. Lower limit of availability for dozer replacement is 0.80. This is ...
    ... around 8 years, excluding model TD 25 M, which exceeded the costs of 70 €/mh during 3" year of operation [1]. Regarding availability, dozer CAT D8R reaches 80% on 8" year, while availability of remaining dozers is reduced to this value between 3" and 5" year. Fact that open-cast mines are having sufficient ...

  • A Fuzzy Expert Model for Availability Evaluation

    Dejan Ivezić, Miloš Tanasijević, Predrag Jovančić, Radiša Đurić (2019)
    Each technical system within itself carries the great potential danger of possible occurrence of failure and damages. Mining machines are characteristic by great investment values, costs of unplanned shutdowns, complex working conditions, and environment and workers hazards. Systematic monitoring of the mining machinery is of great importance for the management of the mining companies. Availability is the overall concept of quality of service. Includes information regard to operating state, an idle state, a standby state and shut down. The ...
    raspoloživost, ekspertski sistem, fazi teorija, buldozeri
    ... 4. Figure 4.a shows the availability level for each machine individually. The machine Cat-F provides the highest level of availability. The availability is evaluated as “excellent” in extent of 33%. The lowest level of availability has the Drs-D machine. The availability is evaluated as “poor” and ...
    ... ty. Availability can also be observed depending on planned breakdowns and delays. The availability is commonly used as a measure of dependability. Availability is expressed by quantitative indicators, and these indicators are measures of dependability and quality of service. Availability performance ...
    ... provide complete information about availability. The obtained result does not provide the availability structure. Delays caused by completing paperwork, waiting for manpower, tools, test equipment or waiting for spares have an influence on machine availability but mostly they are not noted. Therefore ...

  • Availability as a dimension of energy security in the Republic of Serbia

    Boban Pavlović, Dejan Ivezić (2016)
    There is a range of modern approaches and models in literature for the evaluation and determination of energy security, which are based on different parameters and indicators. For most of them, a common characteristic is emphasizing the avail ability of energy, as an important dimension for ensuring energy security. In this paper, concise overview of Serbian energy sectors is given and appropriate energy indicators are defined and determined. Selected indicators provide insight into the main components that characterize availability ...
    raspoloživost energije, energetski indikatori, energetska bezbednost
    ... security. The focus is on a single dimension of energy security – availability. Availability is analysed using com- ponents proposed and described in [1]. However, instead of complex fuzzy approach, each component of availability is analysed by using selected set of indicators. Analytic hierarchy ...
    ... obtained indicators, their interactions and specific importance to availability performance. The proposed procedure for availability indicator determination and their evaluation by AHP is implemented for deter- mination of availability – as a dimension of energy security in Serbia. Concept and dimensions ...
    ... four As. Availability and its indicators Availability, as a dimension of energy security, is very often highlighted as the most dominant dimension of energy security [3-5]. Based on the analysis of reviewed scientific pa- pers within a period of 40 years in 22 countries [6], availability was the most ...

  • Analiza osnovnih indikatora upotrebnog kvaliteta mašina pomoćne mehanizacije na površinskim kopovima uglja

    Stevan Đenadić, Dragan Ignjatović, Predrag Jovančić, Milena Lekić, Žarko Aleksić, Ivan Janković (2022)
    Izbor optimalnog tipa mašine i adekvatno upravljanje kroz životni vek je kompleksan zadatak. Osnovna pitanja koje se postavljaju prilikom rešavanja ovog zadatka vezana su za stepen zadovoljenja rada mašine i optimalan trenutak zamene iste. U ovom radu je izvršena analiza rada dozera koji su u radu na površinskom kopu lignita RB Kolubara. Analizom je obuhvaćeno 4 različita proizvođača dozera a to su: Caterpillar, Dressta i Shantui i Liebherr. Analiza je izvršena sa aspekta ukupnih troškova koji se stvaraju i ...
    rudarstvo, mehanizacija, upotrebni kvalitet, troškovi, empirijska raspoloživost

  • Development of the Availability Concept by Using Fuzzy Theory with AHP Correction, a Case Study: Bulldozers in the Open-Pit Lignite Mine

    Stevan Đenadić, Dragan Ignjatović, Miloš Tanasijević, Uglješa Bugarić, Ivan Janković, Tomislav Šubaranović (2019)
    Availability is one of the most used terms in maintainability engineering. This concept is used to denote: The quality of service of an engineering system, i.e., machines, weak points’ analysis, asset management, as well as making decisions in the process of life cycle management. Availability is an overall indicator and contains partial indicators that are oriented towards reliability, maintenance, and logistical support. Availability presents a variable value and changes in time and space. Usually, availability is shown as the ...
    raspoloživost, fazi teorija, AHP višekriterijumska analiza, eksperska ocena, buldozer
    ... grade of availability (15) of machine B1-N is recorded in the form: A(B1-N) = (0.22922/’A’, 0.28970/’B’, 0.17108/’C’, 0.15354/’D’, 0.15645/’E’) If we designate grade ‘A’ as excellent availability, ‘B’ as good availability, ‘C’ as average availability, ‘D’ as adequate, ‘E’ as poor availability, Equation ...
    ... process of life cycle management. Availability is an overall indicator and contains partial indicators that are oriented towards reliability, maintenance, and logistical support. Availability presents a variable value and changes in time and space. Usually, availability is shown as the coefficient of ...
    ... maintenance support level. The term availability is used to denote the degree of functional safety. Availability is expressed in quantitative indicators, and as such, is a measure of functional safety, and thus of the quality of service. Monitoring and availability analysis are significant because of ...

  • Методологија интегралне анализе сценарија енергетског развоја

    Александар Маџаревић (2019)
    енергетска безбедност, сценарио развоја, фази логика, сигурност снабдевања, доступност, расположивост, природни гас
    ... assessment of the energy security of the energy development scenarios. Energy security is a synthesis of the geopolitical and energy aspects of the availability of energy in various forms and enough quantities at favourable prices. The main goal of the doctoral dissertation is to create a methodology ...
    ... choice of an adequate solution. Key words: energy security, development scenario, fuzzy logic, fuzzy set, security of supply, affordability, availability, natural gas Scientific field: Mining enginering Scientific subfield: Elements of mechanical and energy systems UDC: 005.3:330.34:355.02 ...
    ... појму енергетске безбедности дефинише енргетску безбедност као прекинуту доступност извора енергије по приступачној цени (eng. "an interrupted availability of energy sources at an affordable price") (Radovanovic, M. et al., 2017). Истовремено, кроз оба приступа се огледа и потреба за разматрање енергетске ...

  • Security of Supply as a Major Part of the Energy Security Puzzle

    Aleksandar Madžarević, Miroslav Crnogorac (2022)
    Sigurnost snadbevanja prirodnim gasom Republike Srbije se kroz poslednje dve decenije tretira kao hitno, strateško, političko i bezbednosno pitanje. U sektoru prirodnog gasa, Republika Srbija je veoma zavisna od gasa koji uvozi iz Rusije. Indikatori sigurnosti snadbevanja predstavljaju jedan od osnovnih elemenata za određivanje energetske bezbednosti i snažne alate za usmeravanje energetskog sektora ka održivom razvoju. Metodolaška analiza prikazana u radu je bila koncentrisana na pokazatelje sigurnosti snadbevanja u oblasti energetske bezbednosti koji se odnose na sektor prirodnog gasa ...
    energetska bezbednost, sigurnost snabdevanja, energetski indikator, dostupnost energije, diversifikacija izvora i pravaca

  • Determining the Availability of Continuous Systems at Open Pits Applying Fuzzy Logic

    Miljan Gomilanović, Miloš Tanasijević, Saša Stepanović (2022)
    This work presents a model for determining the availability of continuous systems at open pits by applying fuzzy logic and fuzzy inference systems. The applied model was formed by the synthesis of independent partial indicators of availability. The model is based on an expert system for assessing the availability of continuous mining systems. The availability of the system, as a complex state parameter, is decomposed into the partial indicators, reliability, and convenience of maintenance, and the fuzzy compositions, used ...
    системи, континуални систем експоатације, површински коп, рударство, расположивост, фази логика, max–min композиција, min–max композиција

  • Развој модела употребног квалитета помоћне механизације на површинским коповима лигнита

    Драгица Јагодић Крунић (2021)
    Тренутно стање помоћне механизације на површинским коповима лигнита је незадовољавајуће узроковано пре свега старошћу и неблаговременом заменом машима услед чега је расположивост недовољна а трошкови експлоатације и одржавања високи. Тренутно стање и захтеви који се постављају пред ове машине указују на неопходност оптимизације процеса управљања помоћном механизацијом. Одређивање оптималног времена замене и преосталих могућности је најодговорнији управљачки задатак који треба да буде заснован на свеобухватном сагледавању економских, техничких и других узрочно последичних веза. Са економског аспекта гледано треба одржавати ...
    помоћна механизација, употребни квалитет, ефективност, расположивост, сигурност функционисања, ризик, трошкови животног циклуса, фази логика, Монте Карло метода
    ... (operational availability) техничког система, Ао(t,τ) [27]. У случају када се време у отказу посматра као активно време превентивног и корективног одржавања (време логистичке подршке одржавању се не узима у обзир) може се добити израз за остварену расположивост (realized availability) техничког система ...
    ... Tanasijevic, M., i dr., Development of the Availability Concept by Using Fuzzy Theory with AHP Correction, a Case Study: Bulldozers in the Open-Pit Lignite Mine. 2019. Energies, 12(21), 4044. [17] Ivezic, D., i dr., A Fuzzy Expert Model for Availability Evaluation, 2019 20TH INTERNATIONAL CARPATHIAN ...
    ... lignite mines is unsatisfactory primarily as a result of the machines being old and not replaced on time, which has resulted in their insufficient availability and high cost of exploitation and maintenance. The current state of the machines and the demand placed on them indicate that it is necessary to ...

  • A Model for Determining Fuzzy Evaluations of Partial Indicators of Availability for High-Capacity Continuous Systems at Coal Open Pits Using a Neuro-Fuzzy Inference System

    Miljan Gomilanović, Miloš Tanasijević, Saša Stepanović, Filip Miletić (2023)
    This paper presents a model for determining fuzzy evaluations of partial indicators of the availability of continuous systems at coal open pits using a neuro-fuzzy inference system. The system itself is a combination of fuzzy logic and artificial neural networks. The system availability is divided into partial indicators. By combining the fuzzy logic and artificial neural networks, a model is obtained that has the ability to learn and uses expert judgment for that learning. This paper deals with the ...
    системи, континуални системи експлоатације (роторни багер-транспортер-дробилично постројење), рударство, расположивост, меко рачунарство, фази логика, ANN, ANFIS