Andrzej Niewczas

Chosen Aspects of Municipal Transport Operation on the Example of the City of Lublin

Abstract The paper presents some aspects of operation of municipal transport system in the city of Lublin (Poland). Organization of Lublin Municipal Transport Company was described, its efficiency and perspectives of development. Particular attention was paid to the rules of adjustment to the EU requirements, and to the influence of demographic and social factors. Infrastructure of public transport in Lublin was analyzed (busses, trolley‐busses, bus stations, fixed objects and bus stops), as well as configuration of bus and trolley‐bus lines. Some specific proposals were also put forward regarding development solutions: development plan of trolley‐bus traction, plan of inter‐connection bus station, development plan of bus traction, introduction of advanced IT solutions into the public transport management and natural gas (CNG) fuelling of the city busses. Keywords: urban transport, urban transport problems.

Reliability Evaluation Of The City Transport Buses Under Actual Conditions

Abstract The purpose of this paper was to present a reliability comparison of two types of city transport buses. Case study on the example of the well-known brands of city buses: Solaris Urbino 12 and Mercedes-Benz 628 Conecto L used at Municipal Transport Company in Lublin was presented in details. A reliability index for the most failure parts and complex systems for the period of time failures was determined. The analysis covered damages of the following systems: engine, electrical system, pneumatic system, brake system, driving system, central heating and air-conditioning and doors. Reliability was analyzed based on Weibull model. It has been demonstrated, that during the operation significant reliability differences occur between the buses produced nowadays.

RELIABILITY ANALYSIS OF THE SELECTED BRANDS OF CITY BUSES AT MUNICIPAL TRANSPORT COMPANY / PORÓWNAWCZA ANALIZA NIEZAWODNOŚCI AUTOBUSÓW KOMUNIKACJI MIEJSKIEJ

Abstract The purpose of this paper was to present a reliability comparison of city transport buses on the example of Solaris Urbino 12 and Mercedes- Benz 628 Conecto LF at Municipal Transport Company in Lublin. A reliability index for the most failure parts and complex systems for the period of time up to first damage was determined. It has been demonstrated, that during the operation significant reliability differences occur between the buses produced nowadays. Streszczenie Celem pracy było porównanie niezawodności autobusów miejskich na przykładzie marki Solaris Urbino 12 i Mercedes-Benz 628 Conecto LF w Miejskim Przedsiębiorstwie Komunikacyjnym w Lublinie. Wyznaczono wskaźniki niezawodności najbardziej awaryjnych układów i zespołów w zakresie czasu do pierwszego uszkodzenia. Wykazano, że w praktyce eksploatacyjnej występują znaczące różnice niezawodności pomiędzy współcześnie produkowanymi autobusami znanych firm.

Preliminary analysis of the availability of the medium firefighting vehicles chassis / Wstępna analiza gotowości podwozi średnich samochodów pożarniczych

Abstract The paper presents analysis of the availability of medium firefighting and rescue vehicles chassis used by State Fire Brigade in Warsaw. For analysis of availability of vehicles chassis the technical availability factor has been used. Additionally, in the paper time to restore of the vehicles chassis regarding causes of unavailability has been presented. In the tests the data obtained from the Decision Support System (DSS) of Warsaw State Fire Brigade were applied. The research included the period from January 2012 to May 2015. Based on the results, it can be statement that the operating mileage is the crucial factor of operating degradation of firefighting vehicles chassis. Streszczenie W artykule przedstawiono analizę gotowości podwozi średnich samochodów ratowniczo-gaśniczych użytkowanych przez Państwową Straż Pożarną na terenie miasta stołecznego Warszawa. Do analizy gotowości podwozi samochodów pożarniczych wykorzystano współczynnik gotowości technicznej. Ponadto w artykule przedstawiono czasy odnowy podwozi samochodów w zależności od przyczyn stanu niezdatności. W badaniach wykorzystano dane pozyskane z Systemu Wspomagania Decyzji ST (SWD-ST) Komendy Miejskiej PSP m. st. Warszawa. Zakres badań obejmował przedział czasu od stycznia 2012 r. do maja 2015 r. Na podstawie wyników badań można stwierdzić, że dominującym czynnikiem degradacji eksploatacyjnej samochodów pożarniczych jest przebieg eksploatacyjny pojazdu.

Analysys of reliability and cost of repairs of trucks under long-term lease conditions / Analiza niezawodności i kosztów napraw samochodów ciężarowych w warunkach wynajmu długoterminowego

Abstract The article presents the results of the reliability tests of three makes of trucks. They used samples of 30 vehicles of each make. The vehicles were used by transport companies on a rental basis. The analysis omitted defects of the body-work of the vehicles as the component unrelated to a particular make. The first part of the analysis characterized operating process in respect to mileages and operating time. Then the analysis of the reliability of vehicles and their components was conducted taking into account the mileages till the first recorded defect and separately inter-repair periods’ mileages. The analyses presented are part of a larger work, which aims to develop a method for evaluating the operational quality of trucks from the point of view of the owner of the rental vehicles. Streszczenie W artykule zaprezentowano wyniki badań niezawodności samochodów ciężarowych trzech marek. Wykorzystano próbki liczące 30 sztuk pojazdów każdej marki. Pojazdy były użytkowane przez firmy transportowe na zasadach wynajmu. W analizie pominięto uszkodzenia zabudowy pojazdów jako komponentu niezwiązanego z daną marką. W pierwszej części analizy scharakteryzowano proces eksploatacji w aspekcie przebiegów i czasu użytkowania. Następnie przeprowadzono analizę niezawodności pojazdów oraz ich podzespołów na podstawie przebiegów do pierwszego uszkodzenia oraz osobno na podstawie przebiegów międzynaprawczych. Prezentowane analizy są częścią większej pracy, której celem jest opracowanie metody oceny jakości eksploatacyjnej samochodów ciężarowych z punktu widzenia właściciela wynajmującego pojazdy.

Effectivness Of The Failure Rate On Maintenance Costs Of The City Buses

Abstract The purpose of this paper was to present a failure rate and maintenance cost comparison for two types of city transport buses. The paper presents in detail a case study of well known bus brands used at Municipal Transport Company in Lublin. A failure index of all functional and constructional systems of the vehicles and their technical availability with regards to calendar time was determined. The paper also presents analysis of the factors related to maintenance costs of buses, including costs of fluids, repair costs and maintenance service. It has been demonstrated, that both analyzed buses generate similar maintenance costs, while their failures and technical availability differ significantly in operational practice. These differences are particularly evident in relation to the cumulative costs of repairs.

Study of ceramic-polymer composites reliability based on the bending strength test

Abstract In this paper the reliability assessment of structural reliability of the selected light-cured dental composites based on the biaxial flexural strength test results has been presented. A two-parameter Weibull distribution was applied as a reliability model in order to estimate probability of strength maintenance in the analysed population. Weibull distribution parameters were interpreted as a characteristic material strength (scale parameter) and structural reliability parameter in terms of ability to maintain strength by each of specimen from the general population (shape parameter). 20 composite specimens underwent strength tests, including 2 “flow” type composites and 2 standard composites (with typical filler content). “Flow” type composites were characterized with lower characteristic strength and higher structural reliability comparing to other studied composites.

A numerical model for calculation of piston rings wetted area in a combustion engine

Assumptions made while modelling the oil film between the ring and the cylinder liner in IC engines, especially concerning the boundaries of the wetted area of the ring face surface, were discussed and the assumptions adopted for the developed model were presented in this study. It was assumed that the model should take into account partially flooded lubrication, which meant that the boundaries of the ring wetted area had to be determined. Based on the adopted assumptions, a model for calculation of the oil film thickness between the cylinder and moving rings, and thickness of the oil film left on the cylinder by the ring pack was developed. A computer application operating in the Windows operation system was developed to carry out numerical calculations. The results of initial numerical calculations were also presented. The proposed model can be utilized to determine the effects of the ring pack geometry, especially the geometry of the ring surface, on parameters of lubrication. These parameters, including the oil film thickness, distribution of pressure in oil film or tangential force, are crucial for friction and wear of cooperating surfaces, oil consumption, and flow of gas from the combustion chamber to the crankcase, thus playing a role in the durability, fuel consumption and emission of an engine.

Prediction of IC Engine Power System Durability with the Use of Ring Pack Model

Prediction of IC Engine Power System Durability with the Use of Ring Pack Model The paper presents the new method of engine life prediction, which bases on the results of wear measurements taken on an investigated engine and simulations carried out with the use of the analytical model of ring pack of the engine. In the contrary to traditional methods the proposed method does not require the prior knowledge of the limit wear value, which is essential for the prediction, however its reliable establishing for new engines is difficult. In the presented method its value is determined with the use of the ring pack model. The example of durability calculation for an automotive diesel engine is also presented. Przewidywanie trwałości układu tłok-pierścienie-cylinder silnika spalinowego z wykorzystaniem modelu uszczelnienia TPC W artykule przedstawiono nową metodę prognozowania trwałości silnika, wykorzystującą wyniki pomiarów zużycia elementów układu tłokpierścienie-cylinder oraz wyniki badań symulacyjnych modelu uszczelnienia TPC silnika. W przeciwieństwie do tradycyjnych metod, proponowana metoda nie wymaga wyprzedzającej znajomości zużycia granicznego, która jest kluczowa dla dokładności prognozy, a której wiarygodne określenie dla nowych konstrukcji jest trudne. W prezentowanej metodzie wartość zużycia granicznego wyznaczana jest z wykorzystaniem modelu uszczelnienia TPC. W artykule przedstawiono przykład wykorzystania metody do prognozowania trwałości samochodowego silnika o zapłonie samoczynnym.