bluuebunny/crossref_metadata_2025 huggingface dataset:
KAJIAN EKSPRESIF TERHADAP NOVEL KEMARAU KARYA A.A. NAVIS
Authors: Sanubari Galang Garda , Maslikatin Titik , Saputra Heru S.P.
Published: March 2021

The Drought Novel by A.A. Navis is the object of this research. Tells the life of a middle-aged man who lives in a village. His desire to change the way people around him think about work and make sense of life is hampered by their nature and personal past. Explicitly this novel is like discussing the life of the main character. The reality behind it, culture, innuendo, and religious observance neatly packaged in it. Therefore from that novel that is able to load content in the form of reality and expression of the author, the researcher chooses Dynamic Structuralism as the study theory. Will be achieved in this article the approach used only from the perspective of the expressive approach. The method used is reading, recording, watching, recording data on film sources, and processing data. The results of this study resulted in the study of extrasic (expressive) Sasra works, criticism of the authors of the work on human behavior, the introduction of several Minangkabau cultures, and personal experiences of A.A. Navis
PATRIOTISME TOKOH DEWI AYU DALAM NOVEL CANTIK ITU LUKA KARYA EKA KURNIAWAN
Authors: Choir Anisa
Published: March 2021

This article scrutinizes the patriotism side of the character Dewi Ayu in the novel entitled Cantik Itu Luka by Eka Kurniawan. As a prostitute at Halimunda, Dewi Ayu has an ambiguous nature. She has a tremendous patriotic character, although her profession broke the social norms. This study aims to expose the patriotism of Dewi Ayu in Eka Kurniawan's Cantik Itu Luka. The methodology used in this study is a qualitative methodology approach and a content analysis method by describing the behaviour of Dewi Ayu based on events in the narrative texts. Based on data processing, the study results show Dewi Ayu's patriotism, such as her strict, self-sacrificing, responsible, and a sense of sympathy for indigenous women.
PENGARUH PERCAKAPAN NEGATIF KELUARGA TERHADAP PEMEROLEHAN BAHASA ANAK USIA 3—4 TAHUN
Authors: Maulana Imron
Published: March 2021

The effect of negative conversation occurs intensively in children aged 3-4 years because it is a period of imitation. This period is one of the stages of socialization that a child gets within his family's scope. This study aims to comprehensively examine the negative conversations that affect language acquisition, especially phonological acquisition, mainly acquiring vowels that occur in SM and NS. The research method used is a qualitative descriptive method. The study results revealed that negative conversation significantly affected children's language acquisition and its characteristics. The concrete reality at this stage, especially when the family says anything, then gradually the child brain area will process it. The child will repeat it. This phenomenon occurs repeatedly, and then it is not imagined that he will speak these words spontaneously. A child tends to say it without understanding the meaning. Still, it will affect his character if the negative sentences internalized to his thought. Adopting this negative conversation tends to have unideal characteristics because a child does not imitate his negative words. Still, he tries to understand the meaning uttered by the person closest to him. In this case, the study results reveal that negative conversations significantly affect children's language acquisition and affect their characteristics. The conclusion is that language acquisition through an unfavourable exchange is obtained by internal (family) factors and external factors.
Parental competences in the context of serving a sentence of imprisonment
Authors: Szczygieł Magdalena
Published: March 2021

The presented article adopts the understanding of parental competence as a kind of skill to be developed and improved, rather than a relatively constant human capacity. This approach opens up space for designing parental programmes for prisoners. It is assumed that their competences are subject to change. During imprisonment, these tend to weaken, but it is possible to boost them through well-designed measures. It should be noted here that any pedagogical activity should be based on a diagnosis of the situation. Therefore, the article consists of ﬁ ve parts: a theoretical introduction presenting the basic terminology of parental competence and the situation of an imprisoned parent in the context of stigmatisation; a short methodological analysis; an in-depth description of the research sample; a synthetic perspective on the results of tests obtained using the Parental Competence Test prepared by A. Matczak and J. Jaworska, followed by a summary.
Survey italiano sull’atteggiamento dei clinici verso l’infezione tubercolare latente nelle persone che vivono con HIV.
Authors: Caiazzo Luca , al. et
Published: March 2021

La tubercolosi è una delle maggiori cause di morte prevenibile fra la popolazione HIV nel mondo.
 Le linee guida (LG) WHO e della SIMIT raccomandano di studiare e trattare tutti gli individui HIV positivi con un’infezione tubercolare latente (LTBI). Lo scopo di questo studio è valutare le opinioni e gli atteggiamenti in pratica clinica dei medici italiani che si occupano di HIV su LTBI. Dal 1° dicembre 2019 al 31 gennaio 2020 è stato pubblicato un questionario online, invitando tutti i soci della SIMIT a compilarlo.
Ottanta medici hanno compilato il questionario, da tutta Italia. I risultati hanno mostrato che la maggioranza dei medici che si occupano di HIV pensa che le raccomandazioni delle LG siano evidence-based e utili per la pratica clinica. Tuttavia, solo il 52.5% del nostro campione adotta le raccomandazioni e 16.3% lo fa solo parzialmente. Questa survey sullo screening della LTBI in PLWH ha rivelato una eterogeneità nelle strategie adottate dai medici italiani esperti di HIV ed una parziale implementazione delle LG. LG aggiornate, basate sulle evidenze e su protocolli diagnostico-terapeutici condivisi potrebbero portare ad una migliore gestione della LTBI in HIV.
Origine multifattoriale dell’aumento di peso in una persona con HIV ricevente cART: descrizione di un caso clinico.
Authors: Lai Vincenzo , al. et
Published: March 2021

L'aumento di peso dopo l'inizio della terapia antiretrovirale di combinazione (cART) è comune tra le persone con HIV (PWH), in particolare quelle con deplezione più pronunciata della conta delle cellule CD4+ o basso indice di massa corporea (BMI) pre-ART. All'inizio dell'era cART, l'aumento di peso durante il trattamento era spesso visto come miglioramento delle condizioni cliniche. Negli ultimi due decenni, tuttavia, il BMI dei PWH riceventi cART è costantemente aumentato, e ciò è associato a un aumentato rischio di sviluppare una sindrome metabolica e altre condizioni di comorbidità. Evitare l'aumento di peso nei pazienti in cART potrebbe ridurre tali rischi. A tal proposito vi presentiamo un caso clinico in cui viene analizzato l’andamento nel tempo dei parametri vitali e delle indagini ematochimiche, in relazione al cambiamento dei regimi terapeutici antiretrovirali. Il nostro caso clinico suggerisce come il ruolo dei farmaci antiretrovirali nel causare l’aumento di peso debba essere sempre inserito in un contesto più ampio includente la familiarità, la dieta e l’esercizio fisico praticato dal paziente.
Non-linearity of the contact layer between elements joined in a multi-bolted connection and the preload of the bolts
Authors: GRZEJDA Rafał
Published: March 2021

The paper presents modeling and calculations of multi-bolted connections at the assembly stage on an example of the engine cylinder head-block connection. The physical model of the connection was introduced as a combination of three subsystems: the set of bolts, the joined element and the contact layer between the joined element and the rigid support. The finite element method (FEM) was used for the modeling. Bolts were replaced with hybrid elements. The joined element was modeled with spatial finite elements. The Winkler model of the contact layer has been taken into consideration. The truth of the theorem has been examined, according to which non-linearity of the contact layer has a negligible impact on the final values of the bolt forces in the case of sequential preloading of the multi-bolted connection. The results of the calculations of a selected multi-bolted connection have been compared with the experimental results.
Microstructure analysis in the creep process of a gas turbine blade of the turbine engine
Authors: BŁACHNIO Józef , KUŁASZKA Artur , ZIĘTARA Maciej , CZYRSKA-FILEMONOWICZ Aleksandra
Published: March 2021

The technical condition of gas turbine blades of the turbine engine has a significant impact on the reliability and life span of the turbine and the entire engine. In order to assess the blades technical condition, a visual method, with the use of optoelectronic devices, is used. In order to verify this assessment, metallographic tests are conducted.
The paper presents the results of microstructural tests of the turbine rotor blades made of nickel-based monocrystalline super alloys. The aim of these tests was to determine the consequences of impacting high exhaust gas temperature and stresses occurring during operation on the stability of the blade microstructure. The progress level of the blade microstructure changes in the post-operational stage for different sections towards the blade vertical axis and was compared with the blade microstructure on delivery made of the same super alloy. A varied degree of the microstructure degradation for different blade sections was shown. The changes typical of the high-temperature creep process – γ phase directional growth (rafting), were observed only for the thinnest walls of the upper section of the turbine blade leaf.
Gas turbines – technological development and potential use in CAES systems
Authors: JAKOWSKI Damian , DZIDA Marek
Published: March 2021

This article briefly describes Compressed Air Energy Storage (CAES), focusing on the technological development of one of the key elements of such systems – the gas turbines. It presents the basic parameters and features of gas turbines, as well as turbine classes with example models. Main tendencies in the structural and technological development are discussed. Changes and trends on electric energy markets are becoming more and more dependent on sources with flexible operating characteristics, therefore, the advantages of gas turbines and the reasons for their development are listed as well.
The impact of the piston bearing surface stepped profile microgeometry on friction losses in the supercharged combustion engine
Authors: WRÓBLEWSKI Emil , ISKRA Antoni , BABIAK Maciej
Published: March 2021

The currently designed engines are usually supercharged and are characterized by high values of the boost pressure. As a result high values of maximum combustion pressure are obtained. This in turn leads to the occurrence of high mechanical loads and thermal stresses on elements of the crank mechanism. The piston is the most mechanically and thermally loaded engine component.
Geometry of the gap between piston bearing surface and cylinder liner significantly affects the total friction losses of the internal combustion engine. On the basis of previous research it appears that friction losses depend more on the area of the piston bearing surface which is covered with the oil film than on the thickness of the oil layer separating collaborating parts. Properly designed barrel shape of the piston bearing surface is a way to reduce the oil film cover area. Another shape which could lead to reduce the oil film cover area is the stepped profile. The stepped profile, contrary to the barrel shape, can be obtained by covering the cylindrical or tapered piston bearing surface with a thin layer of graphite. In this paper the results of simulation for the stepped piston bearing surface are presented.
Directions in vehicle efficiency and emissions
Authors: Johnson Timothy V. , Joshi Ameya
Published: March 2021

This paper provides a general review of light-duty (LD) and heavy-duty (HD) regulations, engine technology, and key emission control strategies. The US is placing a stronger emphasis on laboratory emissions, and the LD regulations are about an order of magnitude tighter than Euro 6, but Europe is focusing on real-world reductions. The California HD low-NOx regulation is advancing and may be proposed in 2017/18 for implementation in 2023+. The second phase of US HD greenhouse gas regulations propose another 25-30% tightening beyond Phase 1, beginning in 2021. LD and HD engine technology continues showing marked improvements in engine efficiency. LD gasoline concepts are closing the gap with diesel. HD engines are demonstrating more than 50% BTE using methods that can reasonably be commercialized. LD and HD diesel NOx technology trends are also summarized. NOx storage catalysts and SCR combinations are the lead approach to meeting the LD regulations. Numerous advanced NOx technologies are being evaluated and some promise for meeting the California HD low NOx targets. Oxidation catalysts are improved for both diesel and methane oxidation applications. Gasoline particulate filters (GPF) are the lead approach to reducing particles from gasoline direct injection (GDI) engines. They reduce PAH emissions, and catalyzed versions can be designed for low back pressure. Regeneration largely occurs during hot decelerations.
Current directions in LD powertrain technology in response to stringent exhaust emissions and fuel efficiency requirements
Authors: Bielaczyc Piotr , Woodburn Joseph
Published: March 2021

The major global automotive markets have all set limits for exhaust emissions from new road vehicles, which have become increasingly stringent over the past few decades. There is also considerable pressure to reduce fuel consumption and CO2 emissions – around 80% of all new passenger cars sold globally are subject to some kind of energy efficiency regulation. Such legal requirements necessitate extensive R&D and testing and the entire field is undergoing a period of rapid change. Despite a recent trend towards harmonisation, at present significant regional differences exist, which vary from the analytical laboratory methods specified, the list of regulated pollutants, the numerical values of the emissions limits and the test cycles employed for engine and chassis dynamometer testing of vehicles and their powertrains. Here the key points are reviewed and strategies and technologies employed to deal with these emissions challenges are discussed. Incoming automotive emissions regulations including the WLTP and Real Driving Emissions are discussed and in conclusion likely directions in powertrain technology are identified.
Mathematical models of delaying opening of SIDI injectors formulated on basis of optical tests
Authors: Pielecha Ireneusz , Skowron Maciej , Wisłocki Krzysztof
Published: March 2021

An appropriate moment of the fuel injection start is one of the parameters determining the characteristics of fuel flow from the injector and preparation of fuel-air mixture for combustion. However, knowledge of the characteristics of signals controlling the beginning of the injector opening does not provide enough information about the time of the actual fuel injection, which often leads to incorrect conclusions and decisions in relation to the required changes in the map of injection control.
What was undertaken in this research was an attempt to evaluate the delay times of the actual opening of the high-pressure injectors of gasoline in relation to the time of triggering the current control signals opening the solenoid and piezoelectric injectors. The conducted tests take into account the variability of fuel injection pressure and backpressure prevailing in the operational chamber of the engine. To accurately determine the time of actual start of injection, the optical tests analysing the optical image of the tip of the dispenser were used. Such high resolution images were obtained thanks to high-speed filming with a frequency of 250 kHz (Dt = 0.004 ms). Correlation of the results of these analyses with the records of parameters of the fast-varying processes (voltage and current in the injector) allowed determining the times of the electric and hydraulic delay of the injection for piezoelectric and solenoid fuel injectors. Based on a comparison of the results obtained, it was found that the delay time of fuel injection for a piezoelectric injector of gasoline is about 3.5 times shorter than for a solenoid injector. It was also found that for the injection pressure above 10 MPa the delay is constant and does not depend on the pressure of fuel and the medium.
Experimentally obtained results of the injection time delay were a basis to formulate mathematical models describing the delay of the actual fuel injection in relation to the signal controlling the opening of the injectors. These models take into account the dependence of the injector reaction on the injection pressure and the backpressure in the operational chamber of the engine. The correctness of the obtained models is confirmed by high values of the coefficient of determination (above 0.84).
An innovative system for piston engine combustion with laser-induced ignition of the hydrocarbon fuel consisting carbon nanotubes
Authors: KAŁUŻNY Jarosław , MERKISZ Jerzy , GALLAS Dawid , RUNKA Tomasz , KOZAK Miłosław , PIELECHA Ireneusz
Published: March 2021

The article proposes the concept of a new piston engine combustion system that is designed to meet future-oriented ecological requirements. The concept is to use ethanol as a fuel, in which a slurry of carbon nanotubes would be formed, which are characterized by the ability to ignite using a pulse of laser light fed into the combustion chamber. Modifying the shape of the light beam that penetrates the combustion chamber would allow to control the position and the size of the area in which the ignition of fuel would occur. The originality of the concept is to combine the latest achievements in the field of nanotechnology in the construction of lasers and the production of biofuels, so as to contribute to improving the environmental performance of engines using the existing synergies.The article discusses the prospects for the use of bioethanol as a fuel with zero carbon balance, a critical review of related research on light pulse initiated ignition of hydrocarbon fuels from carbon nanotubes was presented, and a review of studies of laser ignition for conventional fuels. The results of studies of carbon nanotubes suspensions in a variety of fuels conducted by the authors in order to seek solutions for the stable dispersions formation, that are resistant to nanotube agglomeration and sedimentation. The summary indicates directions for further research highlighting the importance of environmental impact.
Tests of urban bus specific emissions in terms of currently applicable heavy vehicles operating emission regulations
Authors: MERKISZ Jerzy , RYMANIAK Łukasz
Published: March 2021

The article presents a study of a city bus in real operating conditions (RDE) from the perspective of the latest regulations for the assessment of specific emissions compliance for heavy-duty vehicles (Euro VI standard). The object of the research was a serial configuration hybrid drive vehicle. Measurements were made in the real driving conditions in Poznan agglomeration. The latest mobile equipment PEMS was used for the measurements. This article presents the details of the EU 582/2011 Procedure in operational conformity assessment, the methodology of the study was discussed, and the obtained results were presented, both in terms of vehicle operating conditions and engine operation, as well as specific emissions evaluation.
Model of exhaust system of a traction diesel engine with pulse supercharging on transient modes
Authors: BABEL Marek , KOSSOV Evgeni
Published: March 2021

A mathematical model of joint operation of a piston engine with pulse turbine drive, compressor as well as air supply of a diesel locomotive is presented in the article. This model in an integral part of the complex engine-generator power unit of a diesel locomotive in steady states and transient conditions, developed by the authors. The periodic process in the exhaust manifold is represented as two specific characteristic ranges which encompass the process of forced exhaust and the scavenging process. The scavenging calculation is carried out jointly with the processes taking place in the inlet manifold of the engine, including inlet devices of the locomotive. The process of forced exhaust is calculated separately from the inlet processes and doesn`t require usage of empirical coefficients of impulsiveness. Both processes are represented as systems of nonlinear algebraic equations describe in the quasi-steady flow of working fluid in the elements of the inlet and exhaust tracts. The gas-dynamic calculation of the turbine in the transition process is conducted while taking into account changes in flow angles on the rotor blades. As a result of numerical calculation of the a8S22W diesel operational indices in transient modes, a satisfactory compliance of the calculated and the experimental results was obtained.
Multi-criteria fuel system optimization with an electronic control unit
Authors: WRÓBLEWSKI Aleksander
Published: March 2021

This paper presents the results of the multi-criteria synthesis of a diesel engine fuel system using the optimization method. The optimization criteria, functional restrictions and quality criteria have been selected. The efficiency of the proposed method was demonstrated using the example of a diesel engine with the Common Rail system.
Cylinder-to-cylinder and cycle-to-cycle variation in combustion process in radial aircraft engine
Authors: GĘCA Michał
Published: March 2021

Cycle-to-cycle variation in combustion in a single cylinder of a radial engine has an impact on that in others and the entire engine. Steady- and transient-state engine operation was investigated, and the transient states were generated by cyclic changes in the timing of fuel injection to a given cylinder, having others operated on the same mixture composition. The measurement of pressure in the combustion chamber allowed for specifying indicated mean effective pressure (IMEP) in all cycles. The time series of IMEP were studied with mathematical techniques of non-linear dynamics, i.e. a wavelet transform and a multifractal analysis. Controlled disturbances in mixture composition in a single cylinder can have an impact on certain cylinders only. Cylinders 3, 5, 7 and 9 are most responsive to such disturbances, which proves their least cycle-to-cycle variation in combustion.
Effect of asymmetric elliptical shapes of the sealing ring sliding surface on the main parameters of the oil film
Authors: WRÓBLEWSKI Piotr
Published: March 2021

This article discusses the results of simulation studies of the effect of selected sealing ring sets with asymmetrical elliptical sliding surfaces on the oil layer thickness distribution over the whole operating range of an internal combustion engine. The problem of calculating the sliding surface coverage with visco-elastic oil film as well as in mixed friction conditions is discussed. The effect of asymmetrical elliptical sliding surfaces particularly on the dimensionless slip and squeeze indicators was determined, defining these surfaces ability to produce an oil film. The research results presented in this article show that there exists a real possibility of friction loss re-duction in the cylinder and sealing rings contact area, while maintaining the oil film continuity between the sliding surfaces.
Improving the environmental performance of the internal combustion engine by the use of in-cylinder catalyst
Authors: ANDRYCH-ZALEWSKA Monika
Published: March 2021

The problems of using the inner surfaces of a combustion chamber as catalytic converters in order to reduce the harmful exhaust emissions were discussed in this paper. The proper choice of the catalyst is one of the most important issues. The interaction between the burned mixture and the catalyst is not limited by the kinetics of the chemical reactions but depends primarily on the flow rate of the reactants to the catalyst surface during combustion. The lifespan of a catalytic layer is determined by the application technique, where plasma spraying is the most popular and most accessible method. However, when it comes to the catalytic coating durability, it is not an efficient option, as ion implantation is indicated shows greater potential in this respect. In this research the coating of aluminum titanium and chromium-nickel have been applied to the engine head and the piston crown. Then the modified catalytic parts were used in a CI combustion engine and the obtained emission results were compared with the reference results. Another set of tests was performed for an SI engine, powered with gasoline and methane, where the piston crown was covered with a thermal layer of zirconium oxide and a catalytic layer of platinum. The beneficial effects of these in-cylinder catalysts on exhaust emissions and the possible problems in the wide spread use of such solutions have been presented.
The influence of vehicle body roll angle on the motion stability and maneuverability of the vehicle
Authors: PARCZEWSKI Krzysztof , WNĘK Henryk
Published: March 2021

The article discusses the impact of design solutions of vehicle suspensions into angles of body roll. It was shown which type of suspensions is better from this point of view. There were examined the dependence of the suspensions parameters on the vehicle body roll angle. The influence of camber angle on the force transmitted to the tire contact with the road surface was analysed. The lateral forces were measured on the test stand. There was tested dependency of lateral forces from the sideslip angle for different angles of camber. Was analysed change of lateral forces generated by camber angle on the vehicle which was made on a scale ~ 1:5 during tests carried out on the testing track. For this purpose, two tests have been selected: first one allowing the measurement in steady motion conditions, the second one with dynamic change of direction of vehicle motion. The graphs show the effect of camber angles on the controllability and stability of the vehicle motion.
The closed-cycle model numerical analysis of the impact of crank mechanism design on engine efficiency
Authors: OPALIŃSKI Marcin , TEODORCZYK Andrzej , KALKE Jakub
Published: March 2021

The research presents a review and comparison of different engine constructions. Investigated engines included crankshaft engines, barrel engine, opposed-piston engines and theoretical models to present possible variations of piston motion curves. The work comprises also detailed description of a numerical piston engine model which was created to determine the impact of the cycle parameters including described different piston motion curves on the engine efficiency. Developed model was equipped with Wiebe function to reflect a heat release during combustion event and Woschini’s correlation to simulate heat transfer between the gas and engine components.Various scenarios of selected engine constructions and different working conditions have been simulated and compared. Based on the results it was possible to determine the impact of different piston motion curves on the engine cycle process and present potential efficiency benefits.
The analysis of temperature disintegration on the body of fuel injector during research on test bench
Authors: OSIPOWICZ Tomasz , ABRAMEK Franciszek
Published: March 2021

Article describes the results of researches fuel injectors on the test bench with using infrared camera. During researches has been verified various fuel injectors (working order and faulty). In results inner leaks fuel injectors have increased return dosages. Few elements influence on this. It is difficult to determine which element could be uses after disassemble. It is possible to determine the source of leaks during analysis decomposition of temperature fuel injector body.
Optimizing the geometry of the connecting rod in opposite pistons engine
Authors: MAGRYTA Paweł , PIETRYKOWSKI Konrad , MAJCZAK Adam
Published: March 2021

The article presents the results of simulations research carried out, using Finite Element Method. The simulations were made in the Abaqus software. Studies were related to the reduction and improving of stress distribution in the connecting rod of opposite pistons combustion engine. The connecting rod has been developed in a 3D environment in the Catia software, then imported into the simulation tool, in which stress tests were performed. The connecting rod was subjected to a compression and stretching tests. Boundary conditions of forces used in simulation tests have been developed on the basis of the dynamic model created in the MSC Adams software. The study included nine iterations of geometric changes of connecting rod. Shape as well as properties such as parametric dimensions (rod length) were changed. The changes were dictated by the reduction of the maximum values of the stresses and the size of the fields with large stress values. As a result of the simulations, the improvement of the connecting rod strength was obtained by its geometrical change (which was obtained by reducing the stress fields).
Diesel combustion in high load situations: a visual analysis of mixture formation and air utilization
Authors: GRÜNEBERGER Patrick , JOCHAM Bernhard , WINKLHOFER Ernst
Published: March 2021

As fuel injection pressures keep rising, questions focus on additional benefits to be gained from the considerable efforts to achieve and handle the fuel pressure increments. The aim of fuel injection processes is to support the mixing of fuel molecules with oxygen. The steps towards this goal include fuel atomization, evaporation, heat transfer from air into the liquid or vaporized fuel together with transport of fuel for best air utilization. Engineering degrees of freedom include the parameters of the fuel injection system and handling of in-cylinder gas conditions. The paper describes basic high pressure flow processes, spray propagation, evaporation and combustion and the mixing of flame clouds with in-cylinder air for oxidation of high temperature soot particles. Experimental evidence of such processes is derived from laboratory flow tests as well as from optically accessed engines operated under conditions relevant for todays passenger car and heavy duty engines.
Research and analysis of the results from the tribotester test for piston
Authors: BORKOWSKA Joanna , KAŹMIERCZAK Andrzej
Published: March 2021

Piston – ring – cylinder assembly of combustion engine has a lot of friction pairs examples, also one of them which decide about fastness to wear, it means first sealing ring – cylinder, called further very simply ring – cylinder unit. During work of this unit we can observe wear of piston, precisely – of coating which is deposited on ring to prolong service life. Objective of this work was to realize a test of roll-block type on tribotester to set durability of piston sample. Within the framework of this test were investigated a prototyped piston’s rings with diamond embankment. Piston rings are made of diamond coating technology with a porous chromium coating, where in pores is deposited on said diamond powder with a grain size about 1 micron. The work will be carried out of an analysis of collaboration piston – rings – cylinder unit in internal combustion engine and an analysis of the use of hard materials in friction pairs, including powders. The work aims to show the possibilities and benefits of the application of new protective coatings to reduce their wearing, which is consistent with the observed trend of technology development.
Firing order selection for a V20 commercial diesel engine with FEV Virtual Engine
Authors: BUCZEK Konrad , LAUER Sven
Published: March 2021

The continuously increasing mechanical and thermal loads of modern engines require optimization of the designs with incorporation of a wide range of different aspects. Application of advanced computer simulations in the development process for most engine components is well established, leading to the creation of well optimized products. However, the optimization of such design variables ike the firing order, which influences engine operation in several disciplines, is still challenging. Considering the ever increasing peak firing pressure requirements, the layout of the firing order in multi-cylinder commercial engines is an efficient way to reduce crank train / overall engine vibration and main bearing loads, whilst controlling engine balancing and preserving adequate gas exchange dynamics. The proposed general firing order selection process for four-stroke engines and, in particular, its first part being the optimization of the firing order based on crank train torsional vibration, is the main topic of this paper. The exemplary study for a V20 high speed commercial Diesel engine regarding the influence of the firing sequence on crank train torsional vibration has been conducted with the multibody dynamics simulation software “FEV Virtual Engine”. It addresses various engine crankshaft layouts and engine applications.
Calculated injection times of divided fuel dose in a compression ignition engine
Authors: KNEFEL Tomasz , NOWAKOWSKI Jacek
Published: March 2021

This study presents analyses concerning control processes of injection times of divided dose of fuel, startning from setting of injection time in controller up to moment of execution in compression ignition engine. Multiple injection doses were analyzed taking into consideration both sums of individual portions of doses as well as gaps between the doses. Studies were performed for various configurations of the doses, with different values of injection times and gaps between the injections. Measurements were performed for three measuring groups containing single-, two-, and five-portion doses. At constant values of time in a given group it have been applied variable injection pressures. The most important factors determining division of fuel dose were discussed.
Modelling of transcritical and supercritical nitrogen jets
Authors: ANTUNES Eduardo , SILVA Andre , BARATA Jorge
Published: March 2021

The present paper addresses the modelling of fuel injection at conditions of high pressure and temperature which occur in a variety of internal combustion engines such as liquid fuel rocket engines, gas turbines, and modern diesel engines. For this investigation a cryogenic nitrogen jet ranging from transcritical to supercritical conditions injected into a chamber at supercritical conditions was modelled. Previously a variable density approach, originally conceived for gaseous turbulent isothermal jets, imploying the Favre averaged Navier-Stokes equations together with a “k-ε” turbulence model, and using Amagats law for the determination of density was applied. This approach allows a good agreement with experiments mainly at supercritical injection conditions. However, some departure from experimental data was found at transcritical injection conditions. The present approach adds real fluid thermodynamics to the previous approach, and the effects of heat transfer. The results still show some disagreement at supercritical conditions mainly in the determination of the potential core length but significantly improve the prediction of the jet spreading angle at transcritical injection conditions.
Modelling the impact of microbial contamination of fuel filtration efficiency
Authors: KRAKOWSKI Rafał
Published: March 2021

In this paper the concept of filtration and the problem of microbial contamination occurring in the fuels and oils was presented. Then the factors influencing the growth of bacteria in petroleum products were described in detail. In the next part of the article modeling of the impact of fuel microbial contamination on filtration efficiency was performed. The modeling presented in the article is an example showing how undesirable phenomenon is the microbial contamination and how pollution affects the other elements of the entire system. As part of the modeling, numerical model of filtration with the solution was presented. Then analysis results on the basis of the impurities concentration characteristics in the fuel as a function of the fouling thickness in the partition of the filter is performed. The development of impurities was divided into three stages. In the article for one case the trend line was presented. The article was completed conclusions.
Numerical investigation into the effect of direct fuel injection on thermal stratification in HCCI engine
Authors: GĘCA Michał , HUNICZ Jacek , JAWORSKI Piotr
Published: March 2021

Despite the fact that HCCI engines are distinguished by mixture homogeneity, some degree of stratification always appears inside a combustion chamber. It is especially applied to residual effect engines utilizing negative valve overlap. Mixture stratification is a result of the imperfect mixing of fresh air with trapped residuals. Direct fuel injection introduces stratification as well, due to fuel vaporization.
As a consequence, the temperature within the combustion chamber is uneven. Thermal stratification affects auto-ignition timing and combustion evolution in a high extent. The purpose of this study was to evaluate a degree of thermal stratification in HCCI engine utilizing negative valve overlap. Investigations were performed using three-dimensional CFD model of the combustion system, made by using AVL FIRE software. Simulations were realized for various timings of fuel injection into the cylinder. It was found that fuel injection timing had a significant effect on the thermal stratification and resulting auto-ignition timing.
Nissan gasoline engine strategy for higher thermal efficiency
Authors: MIZUNO Hideaki
Published: March 2021

Rising highly concern about the environment has led to demands for the improvement of the efficiency of gasoline engines. Engine thermal efficiency will reach about 40% by technologies as boosted EGR, miller cycle and so on. This evolution trend will be continuously required to survive engines for the future. In this background, further improvement based on theoretical thermal efficiency of high compression ratio and specific heat capacity should be promoted. In addition, energy loss reduction such as represented by cooling loss and friction is also very important for the efficient and effective improvement. NISSAN’s challenges will be introduced to solve these propositions.
Usage of wing in ground effect to maintain lift force with reduced fuel consumption of aircraft
Authors: ROJEWSKI Adam , BARTOSZEWICZ Jarosław
Published: March 2021

The main purpose of this article was to point out causes of reduced fuel consumption in aircraft jet engine when aircraft is in ground effect influence. Wing in ground effect occurs in the direct proximity of ground. The paper presents wing in ground effect description, with the numerical analysis of NACA M8 airfoil in three different conditions of flight. Numerical analysis was conduct in Ansys Fluent 17.2 software. The paper shows results of simulations which describes wing in ground effect influence on NACA M8 airfoil with two cases of jet engine exhaust gasses usage, first with exhaust gasses stream turns on upper airfoil surface, and second with exhaust gasses stream turns under lower airfoil surface. Results allow to define characteristics of NACA M8 airfoil in the influence of wing in ground effect which are lift coefficient, drag coefficient, drop of fuel consumption usage by the jet engine when lift force remains still in the wing in ground effect. The paper shows that in the wing in ground effect aircraft energy usage for flight in ground effect is smaller than for free air flight.
The emissions reduction possibility of sulphur compounds of vessels sailing in Emission Control Areas (ECA)
Authors: KRAKOWSKI Rafał
Published: March 2021

The article presents legal regulations, together with the characteristics of Emission Control Areas (ECA). It is connected with the new limit sulfur emissions in those areas. In this article , the advantages and disadvantages of various solutions, i.e. switching to low sulphur distillates, installing the marine scrubber device and using of liquefied natural gas (LNG) as ship’s main fuel have been considered. Each of these solutions was described in respect of technological review, by the possibility of reducing harmful compound from exhaust gases, to investment costs. In another part of this thesis, there are the calculations of costs of fuel and necessary modifications for a selected passenger-car ferry. Costs were assessed for all of the mentioned solutions. The article was completed conclusions indicating which way is the most cost-effective.
The impact of starting process on wear of cylinder wall
Authors: LEWKOWICZ Ryszard , PIĄTKOWSKI Piotr , ŚCIEGIENKA Ryszard , SZYMANIUK Błażej
Published: March 2021

The results of experimental research of cylinder wall wearing process were presented in this article. Researches were conducted onthe basis of four strokes spark ignition one cylinder engine. The main goal of presented research was assessment of impact of cold start condition on intensity of cylinder wall wearing process. The new one and worn engine oil with grade 10W40 was used for experimental research. The experimental research was conducted on specially developed experimental stand. The wear of cylinder wall was assessed on the basis of cylinder diameter and wall roughness measurements.
Assessment of the potential of dimethyl ether as an alternative fuel for compression ignition engines
Authors: SMOLEC Rafał , IDZIOR Marek , KARPIUK Wojciech , KOZAK Miłosław
Published: March 2021

The main problem that the automotive industry has been dealing with since the beginning of the XXI century is the need to reduce the exhaust emissions from piston combustion engines. Another, not at all less important problem is the depleting natural resources of crude oil. There are many concepts aiming at resolving of the said issues. One of them is the possibility of application of dimethyl ether (DME) in a classic engine. The paper characterizes this fuel, drawing attention to the aspects related to the adaptation of the engine to this type of fuel, presents the process of its atomization and relevant exhaust emissions.
Diagnosing the automobile starting system
Authors: DZIUBIŃSKI Mieczysław , DROZD Artur , KORDOS Paweł , SYTA Arkadiusz
Published: March 2021

This article presents a new method for analysing the torque of an internal combustion engine using registered electromechanical runs and magnetic field distribution in a starter. The aim of the study was to develop a model of the starting current of an internal combustion engine and carry out verification tests on real objects. The developed model allows to simulate the shutdown of individual cylinders. Experimental research was conducted using the Bosch FSA 740 equipment for four internal combustion engines under variable operating conditions. During testing, the starting current and relative compression in cylinders were recorded. Simulating the variable load of the starter, the magnetic induction distribution of the magnetic induction was recorded in the feed slot. The research will be used to develop a method of diagnosing the starter and determining the torque of the internal combustion engine.
Testing of the fleet of the vehicles with diesel engines fed by BIOXDIESEL fuel
Authors: STRUŚ Mieczysław , POPRAWSKI Wojciech , REWOLTE Mariusz
Published: March 2021

The paper presents results of testing of the fleet of the parcel delivery vehicles, equipped with the Diesel engines fed by biofuel BIOXDIESEL, manufactured on the way of the ethanol esterification process of the waste vegetable and animal fats, with the addition of the standard diesel fuel and pure ethanol. The comparison results of the vehicles test bed on the beginning of the testing and at the end of the testing, when vehicles were fueled with standard diesel and testing biofuel. The results of the testing at non-stationary states are also presented. The paper presents also results of the drivers evaluation of the performance of the vehicles based on the questionnaire. Presented results show that the BIOXDIESEL fuel is fully replaceable to the standard diesel fuel.
Determining the environmental indicators for vehicles of different categories in relation to CO2 emission based on road tests
Authors: MERKISZ Jerzy , RYMANIAK Łukasz
Published: March 2021

The article discusses the possibility of determining the environmental indicators for vehicles of different categories in relation to CO2 emissions. These are called toxicity indicators because they concern the compounds: CO, THC and NOx. Three Euro V compliant vehicles with different propulsion systems types were used for the study: a 0.9 dm3 urban passenger car with a SI engine and a start-stop system, a 2.5 dm3 off-road vehicle with a CI engine, and a city bus with a hybrid drive system in series configuration and a CI engine with a displacement of 6.7 dm3. Measurements were made in actual operating conditions in the Poznan agglomeration using a portable emissions measurement system (PEMS). The paper presents the characteristics of the operating time shares of vehicles and propulsion systems as well as CO2 emissions depending on the engine load and crankshaft rotational speed for individual vehicles. The determined toxicity indicators allowed to indicate their usefulness, to make comparisons between tested vehicles, and to identify directions for further work on the application and interpretation of these indicators.
The influence of the injection frequency on the urea selective catalytic reduction systems performance
Authors: ROGÓŻ Rafał , JAWORSKI Piotr , KAPUSTA Łukasz Jan , TEODORCZYK Andrzej
Published: March 2021

This study presents the influence of the UWS injection frequency on a close coupled SCR systems performance. The investigation was performed with the CFD tool AVL Fire. In the paper the analysis of four different UWS injection frequencies in the three different operating points of diesel engine was shown. The assessments of the system performance was referred to the ammonia distribution at catalyst intake and wall film formation inside the investigated geometry, as these are considered as crucial in such a configuration. The results showed that injection frequency affects both factors on different level depending from the flow conditions. In addition, the wall film crystallization risk was discussed basing on the obtained wall film characteristics.
The influence of the throttle inclination characteristics of a SI engine on fuel consumption in driving cycles
Authors: HENNEK Krystian , GRABA Mariusz , MAMALA Jarosław
Published: March 2021

This dissertation shows the analysis of the selected indicators of the work of a passenger vehicle drivetrain designated with the use of the Road Load Engine Simulator. In a digital simulation, an internal – combustion engine is saved in a form of numerical speed characteristics in the computers memory. Basing on a virtual vehicle, some indicators of the drivetrain of a passenger vehicle have been determined, while driving with five electronic throttle inclination regulator settups. The simulation results of e.g., throttle repeal speeds and fuel consumtion are summarized in a tabular and graphic form and some of them are expressed per 100 kilometer of the distance covered. Both synthetic and real driving cycles were analyzed during the study and their influence on the egines fuel consumption was also shortly described.