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Emission of Selected Exhaust Gas Components and Fuel Consumption in Different Driving CyclesAndrzej Kuranc, Jacek Caban, Branislav ©arkan, Agnieszka Dudziak, Monika StomaCommunications - Scientific Letters of the University of Zilina 2021, 23(4):B265-B277 | DOI: 10.26552/com.C.2021.4.B265-B277 Road transport have significant impact on regional economic and social development, but one can also point out a number of its disadvantages, which include environmental pollution. The paper presents measurements of fumes exhaust emissions of a passenger car with a significant operational mileage. The tests were carried out in a laboratory on a chassis roller dynamometer using various driving cycles. To determine the exhaust emissions, data on the mass of air flowing through the intake manifold was used, among others. The work also describes an example of own driving cycle developed based on urban driving in Lublin, Poland. |
Assessment of Technical Condition of an Accumulator Common Rail Injector by Temperature of its UnitsIldar Gabitov, Andrei Negovora, Azamat Valiev, Vladimir Ilin, Danila Plotnikov, Mahmut RazyapovCommunications - Scientific Letters of the University of Zilina 2021, 23(2):B130-B138 | DOI: 10.26552/com.C.2021.2.B130-B138 This paper presents a method for the vehicle speed estimation with a Fuzzy Logic based algorithm. The algorithm acquires the measurements of the yaw rate, steering angle, wheel velocities and exploits a set of five Fuzzy Logics dedicated to different driving conditions. The technique estimates the speed exploiting a weighted average of the contributions provided by the longitudinal acceleration and the credibility assigned by the Fuzzy Logics to the measurements of the wheels' speed. The method is experimentally evaluated on an all-wheel drive electric racing vehicle and is valid for the front and rear wheel drive configurations. The experimental validation is performed by comparing the obtained estimation with the result of computing the speed as the average of the linear velocity of the four wheels. A comparison to the integral of the vehicle acceleration over time is reported. |
Firefighting Vehicles Braking Distance MeteringIzabela Sudrychova, Jiri Kuczaj, Ladislav Janosik, Pavel Polednak, Ivana JanosikovaCommunications - Scientific Letters of the University of Zilina 2019, 21(3):85-91 | DOI: 10.26552/com.C.2019.3.85-91 The paper topic is concerned with the issue of braking dynamics and adhesion coefficients of firefighting vehicles at fire rescue units. The real breaking distances at firefighting vehicles of the water tenders type are presented in the paper. The metering was made on the wet and/or dry asphalt, with different age of tires and the carload. Measured results should be used for drivers' education at fire rescue units to increase the safety during the emergency drives. |
Calculation of the Vehicles Stress-Deformed State while Transporting the Liquid CargoOleksii Grevtsev, Ninel Selivanova, Pavlo Popovych, Liubomyr Poberezhny, Oksana Shevchuk, Igor Murovanyi, Andrii Hrytsanchuk, Liubov Poberezhna, Vasyl Zapukhliak, Galyna HrytsuliakCommunications - Scientific Letters of the University of Zilina 2021, 23(1):B58-B64 | DOI: 10.26552/com.C.2021.1.B58-B64 To calculate the stress-deformed state of road-tanker metal structures during the liquid cargo transportation, the solution for bending axially and symmetrically loaded circular plates is proposed, which is based on the theory of elasticity approach. Dependencies for calculating stresses and displacements under arbitrary load law and support type are substantiated. Deformation of the support under the action of axisymmetric loading leads to appearance of a temperature field. |
Evaluation of Impact of the Operational and Technical Factors on Downtime of Municipal Buses Based on a Linear Regression ModelJoanna Rymarz, Anna Borucka, Andrzej NiewczasCommunications - Scientific Letters of the University of Zilina 2021, 23(4):A241-A247 | DOI: 10.26552/com.C.2021.4.A241-A247 The objective of this study was to assess the effect of selected operational and technical factors on downtime of vehicles. The sample consisted of buses from a municipal transport company (Poland). Estimation of parameters of a linear regression model was performed. Month of failure (downtime event) and its type were used as predictors. Failures were divided into three categories: events related to the company´s operations, including vehicle failures (1) and other (organizational) problems (2), as well as failures caused by external factors unrelated to the operations of the transport company (3). The downtime was found to be significantly associated with failure type and month of failure. A linear regression model of downtime with a reduced number of impact factors, taking into account two main failure types and two main periods of their occurrence during the year, was developed. |
E1 Signal Processing of the Galileo System in the Navigation ReceiverLucjan Setlak, Rafał KowalikCommunications - Scientific Letters of the University of Zilina 2021, 23(3):E46-E55 | DOI: 10.26552/com.C.2021.3.E46-E55 The subject of this article are issues related to the navigation system in the field of analyzing the processed signal in the GNSS system receiver. The main purpose of the work is to discuss the Galileo E1 signal processing methods in the GNSS navigation system receiver, supported by adapted research tools in terms of solving the research problem (analysis, model, simulation tests) and the mathematical apparatus used. Key studies are concentrated around the process of generating the navigation data, dispersing sequences and signal modulation. Thus, when designing a receiver, it is better to use the simulation signals than the real ones, since one can get more control over the properties of the received signal. In the final part of the work, in accordance with the subject of research, based on the developed appropriate research tools, observations and final conclusions were formulated, which have practical applications. |
Improvement of the Logistic Processes using the Reverse Logistics ConceptZbigniew Lukasik, Aldona Ku¶mińska-Fijalkowska, Sylwia OlszańskaCommunications - Scientific Letters of the University of Zilina 2021, 23(3):A174-A183 | DOI: 10.26552/com.C.2021.3.A174-A183 Reverse logistics differs significantly from such fields as management of waste, of which the goal is, above all, efficient and effective collection and processing of waste. Therefore, it can be said that reverse logistics refers to such streams of flows in which it is possible to recover the value from discontinued products and situation, in which solution is contribution to a new supply chain. Therefore, in this aspect, the fundamental pillar is transport, in which the crucial element is management of transport process, above all, planning of changes improving this process to better control the degree of their execution. |
The Continuous Monitoring of Selected Railway Structures using the Autonomous Data LoggerDusan Janostik, Viktor Nohal, Herbert Seelmann, Jaroslav SmutnyCommunications - Scientific Letters of the University of Zilina 2020, 22(2):88-96 | DOI: 10.26552/com.C.2020.2.88-96 This contribution focuses on issue of the autonomous monitoring of selected dynamic parameters of the railway lines test sections under conditions in the Czech Republic. Description of the possibilities of such data collection, including the designed hardware and software, is a part of this contribution. At the same time, the contribution describes application of such a measuring system, comparing the selected dynamic parameters of the two types of switches, the first one was a switch with a standard fastening node, the other one with an elasticized fastening node. Recommendations and conclusions of railway infrastructure manufacturers and railway line managers are parts of this contribution, as well. |
Web Site Contents of Municipal Transport Undertaking as a Modern Communication Tool for Enhancing Quality of Transport ServicesPavel Drdla, Jan HrabacekCommunications - Scientific Letters of the University of Zilina 2005, 7(2):46-48 | DOI: 10.26552/com.C.2005.2.46-48 The paper deals with web site contents of Municipal Transport Undertakings. In the paper there are introduced kinds of information in use improving and intensifying communication between customers (passengers) and transport operators. These data come from research results of several Municipal Transport Undertaking web sites.There is also mentioned an informative minimum, which is found to be necessary and should not be omitted. |
Investigation of the Impact Strength of the Epoxy-Polyester Material for Using in Aggressive Environments in the Water TransportSerhii Yakushchenko, Mykola Brailo, Andriy Buketov, Anna Sapronova, Oleksandr Sapronov, Abdellah MenouCommunications - Scientific Letters of the University of Zilina 2021, 23(4):B346-B353 | DOI: 10.26552/com.C.2021.4.B346-B353 The influence of the aggressive environments of river water, seawater, oil, petrol and sodium hydroxide on the impact strength of epoxy-polyester composite was investigated. Testing was conducted by two different methods. It was determined that the impact strength of specimens that were kept at air was W' = 4.2 kJ/m2 (by the second method - W'' = 7.0 kJ/m2). The energy spent on destruction of the control specimen was E = 0.92 J. The main regularities of the crack propagation process in the studied material were found and qualitatively described. The time of a crack propagation (τ = 0.16 μs) was determined. The maximum load, which leads to destruction of the specimen was Pmax = 2.47 kN. The comparative analysis of investigated specimens was conducted by the IR-spectroscopy method. It was found, that the biggest decrease in material properties was observed for the specimen that was kept in the petrol environment. |
Improvement of Traction Indicators of a Track-Chain TractorSalavat Mudarisov, Ilshat Gainullin, Ildar Gabitov, Eduard KhasanovCommunications - Scientific Letters of the University of Zilina 2020, 22(3):89-102 | DOI: 10.26552/com.C.2020.3.89-102 The aim of this research was to conduct the comparative traction tests for T-170M1.03-55 tractor with a flat and elliptical rim. Structurally rational geometry of the crawler's support surface for tractors with semi-rigid suspension is realized by placing the support rollers at different heights relative to the cart. The results of traction tests showed that elliptical track rim has increased the maximum traction power by 10.4%, conditional traction propulsive efficiency coefficient to 7.43% and the specific traction effort by 8%. The increase in indicators is provided by a lower rolling resistance of a tractor with an elliptical rim. Reduction of the resistance power to rolling of the tractor with an ellipse track rim occurs due to alignment of support rollers vertical load and reduction of resistance to rollers movement on internal contours of tracks and in hinges of track chain links. The results of the research indicate a significant improvement in traction performance of T-170M1.03.55 tractors with elliptical track-chain rim. |
Models of the Computer Intellectualization Optimal Strategy of the Power Supply Fast-Flowing Technological Processes of the Railways Traction SubstationsAleksander Stasiuk, Valeriy Kuznetsov, Lidia Goncharova, Petro HubskyiCommunications - Scientific Letters of the University of Zilina 2021, 23(2):C30-C36 | DOI: 10.26552/com.C.2021.2.C30-C36 Based on analysis of the problem of the power supply networks of railways innovative transformation, the direction of research is substantiated related to organization of the optimal strategy of computerized intellectualization of the power supply processes to the railways traction substations. The logical structure of a distributed computer environment developed in the form of graph, which adequately reflects the topology of the organization of the power supply system. A differential mathematical model of the computer architecture of the power supply control is proposed. An intelligent method for finding the optimal strategy for the intellectualization of the power supply processes was proposed to guarantee the specified indicators of the optimal functioning of individual nodes and segments of the power supply management computer network. |
Analysis of Vehicle Moving Parameters in Various Road ConditionsRafał Jurecki, Tomasz StańczykCommunications - Scientific Letters of the University of Zilina 2021, 23(3):F58-F70 | DOI: 10.26552/com.C.2021.3.F58-F70 The safety of road users is one of the priority issues raised by those involved in vehicle design, latest passive and active safety systems, traffic organization or driver education. Nowadays, an important road safety problem is the behaviour of drivers in emergency situations. In order to measurably estimate the driving quality, parameters such as velocity, acceleration, the way and frequency of using the control pedals are quite often used. This article describes how to assess driver's behaviour based on measurements taken on the road. The frequency of different acceleration ranges during the vehicle drive was determined based on the results obtained. For the arbitrarily adopted acceleration range of - 0.5 - 0.5 m/s2, the driver's working time was over 77 percent on average, with the difference varying significantly between different route sections. Similarly, the study compares the driving times for other ranges of acceleration. |
Technical Feasibility of Deceit While a Vehicle is Weighed in Motion with a Very Low SpeedZbigniew LoziaCommunications - Scientific Letters of the University of Zilina 2021, 23(1):D1-D14 | DOI: 10.26552/com.C.2021.1.D1-D14 The study concerns the problem of overloading the vehicles driven on public roads. The gross vehicle mass and individual axle loads are limited by legal regulations. However, a tricking method, applicable to most popular designs of motor vehicles and multiaxial tractor-semitrailer units, has been shown that the weighing inspectors, even if provided with precise scales, may be deceived without any interference in the scale operation. In such a method, the current vehicle state may be changed by modifying the stiffness of individual pneumatic suspension springs, which is now technically feasible. The author used two authorial vehicle models and a simulation program. Calculation results obtained for a four-axle motor vehicle and a five-axle tractor-semitrailer unit, taken as an example, have been demonstrated. They show that a deceit is possible when a vehicle is weighed in motion with a very low speed. |
Decomposing the Influencing Factors of Energy Intensity in the Passenger Transportation Sector in IndonesiaDhani SetyawanCommunications - Scientific Letters of the University of Zilina 2020, 22(3):49-58 | DOI: 10.26552/com.C.2020.3.49-58 Indonesia's transport sector has experienced rapid growth that has caused excessive fossil fuel energy consumption. Over 2000 to 2016 total final energy consumption in Indonesia's transport sector has grown by 10% per annum so that transport now provides a large and rapidly growing component of total energy use. This study analyzes the specific characteristics of energy intensity in the transportation sector in Indonesia from 2000 to 2016 by employing a multiplicative Log Mean Divisia Index-II. The passenger transport sector in Indonesia, including the four modes of road, rail, water and air is examined in this study. Overall, the decline in energy intensity in passenger transport is attributed to the intensity effect. In passenger transport, the improvement of intensity effect was found to have significantly reduced the overall aggregate energy intensity, while the change in structural effect was found to have a relatively small reduction in the aggregate energy intensity. |
Consolidation of Cargos in the Road Transport as a Key Method to SuccessZbigniew Łukasik, Aldona Ku¶mińska-Fijałkowska, Jacek Kozyra, Sylwia OlszańskaCommunications - Scientific Letters of the University of Zilina 2021, 23(1):A54-A61 | DOI: 10.26552/com.C.2021.1.A54-A61 The problem of consolidation of goods for the provider of logistic services, which is a third part that delivers goods from many suppliers to one business client in time horizon was analysed in this article. Every parcel has a fixed date of reception in the source and delivery schedule in a destination. In the age of highly developed economy, time pressure and costs, outsourcing is a condition necessary to improve the functioning of enterprises. New logistic chains, networks of terminals and intermodal connections are built every year to reduce the transport costs and improve the whole process. In this article, the authors presented the benefits resulting from consolidation of cargos in the road transport. Special emphasis was put on determination of the role of the transport costs reduction using the cargo consolidation services. |
Energy Characteristics of the DC Distributed Power Supply SystemsViktor Sychenko, Valeriy Kuznetsov, Artur Rojek, Petro Hubskyi, Yevhen KosarievCommunications - Scientific Letters of the University of Zilina 2021, 23(2):C37-C43 | DOI: 10.26552/com.C.2021.2.C37-C43 Currently the circuit technology of the DC traction power supply system cannot provide the necessary requirements for introduction of high-speed traffic. Numbers of measures and tools have been developed to improve the traction lines that no longer meet current requirements. One of the most promising means for strengthening the traction DC lines is transition to the distributed power supply of the rolling stock. In this article, a comparative analysis was carried out of energy indicators of the classic centralized power system and distributed power systems with use of one aggregate traction substation and with use of the solar generators. That comparative analysis of these systems was performed on a simulation model with the same parameters of the traction line and rolling stock. |
Unique Police Training Polygon in Terms of Activity and Training Improvement of the Intervention Units of the Police of the Czech RepublicMartin HrinkoCommunications - Scientific Letters of the University of Zilina 2017, 19(4):111-116 | DOI: 10.26552/com.C.2017.4.111-116 The report describes project works and the purpose of a special training polygon designated for police officers of intervention units of the Police of the Czech Republic. It is a completely unique training facility newly built for the law enforcement officers. It concerns the outstanding project in conditions of the Police of the Czech Republic, which contains extreme situations and conditions which police officers of intervention and special units can meet in their practical performance of service. In the limited extend this applies also for the training of tactics for members of firstly coming patrols and emergency units. |
Sources of Financing Public Passenger Transport ServicesMilos Poliak, Lenka Komackova, Salvador Hernandez, Marek Jaskiewicz, Gabriela BoldizsarovaCommunications - Scientific Letters of the University of Zilina 2017, 19(2):120-126 | DOI: 10.26552/com.C.2017.2.120-126 The paper deals with the financing of public passenger transport. It analyses unconventional types of financing public passenger transport abroad. The aim of the paper is to present the methodology of creating funding sources for the financing of public passenger transport which is applicable in the Slovak Republic and in the member states of the European Union. The key idea of the methodology is to use funding sources arising from the provision of public services. |
Theoretical Calculations of Economic Life of Firefighting Appliances Based on Chassis Tatra in the South Moravian RegionLadislav Janosik, Ivana Janosikova, Pavel PolednakCommunications - Scientific Letters of the University of Zilina 2018, 20(2):49-55 | DOI: 10.26552/com.C.2018.2.49-55 This paper is focused on the evaluation of economic data obtained from operational records of firefighting equipment with a focus on firefighting and rescue appliances, especially on exit vehicles based on the chassis CAS 20 - TATRA T815-231R55 18 325 4x4.2. These vehicles have been operated by professional units of the Fire and Rescue Service in the South Moravian Region since September 2013. The producer of firefighting superstructures WISS GROUP, Bielsko-Biala, Poland, was a supplier of all these vehicles. The paper's aim is to specify the optimum lifetime of the firefighting vehicles by the analysis of firefighting vehicles' economical operation. Theoretical calculations of the optimum lifetime have been processed with implementing both the method of exponential trends and the Brown method. The residual value of vehicles has been calculated both according to the current Czech tax law, and to the Expert Standard Valuation of motor vehicles in force in the Czech Republic. |
Proportionally Fairer Public Service Systems DesignLubos Buzna, Michal Kohani, Jaroslav JanacekCommunications - Scientific Letters of the University of Zilina 2013, 15(1):14-18 | DOI: 10.26552/com.C.2013.1.14-18 This paper focuses on the utilitarian solution of public service system design problem, obtained when maximising the sum of all utilities and proportionally fair-like solution, taking into account proportional changes in individual utilities. As an archetypal example of the optimisation problem, we are examining the weighted p-median problem, which is solved by the primary-dual based procedure. We use realistic largescale data describing the road network and spatial distribution of population. By comparing the resulting solutions, for selected range of parameters, we evaluate how costly it is to consider fairness criteria in the service system design. As for integer problems the proportional fairness scheme does not guarantee the existence of dominant optimal solution, we evaluate the close neighbourhood of obtained solutions. Based on these analyses we draw conclusions on the price of (proportionally-like) fair solutions and their stability. |
Accuracy Assessment of Aircraft Positioning Using the Dual-Frequency GPS Code Observations in AviationKamil Krasuski, Stepan SavchukCommunications - Scientific Letters of the University of Zilina 2020, 22(2):23-30 | DOI: 10.26552/com.C.2020.2.23-30 This study publishes results of tests with regard to determination of the aircraft positioning accuracy by means of the GPS navigation in aviation. The research exploits the mathematical model of the linear combination "IonosphereFree" in order to designate the coordinates of an aircraft. The research uses the actual GPS code observations, recorded by a satellite receiver mounted in the Cessna 172, at the time of the experiment for the EPDE military aerodrome in Dęblin. The computations of the position of the Cessna 172 aircraft for the linear combination "Ionosphere-Free" were made in the APS Toolbox v.1.0.0. programme. Within evaluation of accuracy of the GPS positioning in aviation, the determined coordinates of the aircraft Cessna 172 from the APS programme were compared to an accurate reference position from the solution derived by the PPP measurement technique. In the research, the authors obtained an average positioning accuracy of approximately 5 m in the geocentric XYZ coordinates and approximately 4 m in the ellipsoidal BLh coordinates. In addition, the 3D-error parameter is lower than 7 m for the XYZ geocentric coordinates. |
Functional Safety for Developing of Mechatronic Systems - Electric Parking Brake Case StudyJuraj Pancik, Peter Drgona, Marek PaskalaCommunications - Scientific Letters of the University of Zilina 2020, 22(4):134-143 | DOI: 10.26552/com.C.2020.4.134-143 The electric parking brake (EPB) system as the complex mechatronic system consists of the actuators that generate the clamping force necessary to hold the vehicle safe, the conventional calipers that convert clamp force into brake torque, electronic hardware with the Electronic Control Unit (ECU), cable harness and switches and especially the control software providing the functions that the driver will experience. Like most of the modern automotive components, the EPB is equipped with embedded electronic systems that include ECU, electronic sensors, signals, bus systems, and coding. Due to the complex application in electrical, electronics and programmable electronics, the need to carry out detailed safety analyses that are focused on the potential risk of malfunction is crucial for automotive systems. This paper describes a possible division of the EPB sub-functions between the supplier the wheel brakes and the supplier which supplying the ECU. Functional safety must be a guarantee with concerning the overall vehicle system. Functional safety is according to the requirements of the ISO 26262 standard and in the context of this paper relates solely to the E/E components (electrical and/or electronic) of the EPB. This paper covers the hazard analysis and risk assessment relevant to the EPB control software, and the derived allocation of ASIL risk levels to the EPB software elements of the functional architecture of the EPB. |
The History of the Transport System Development and Future with Sharing and Autonomous SystemsGeza Katona, Janos JuhaszCommunications - Scientific Letters of the University of Zilina 2020, 22(1):25-34 | DOI: 10.26552/com.C.2020.1.25-34 The world today is rapidly changing with the spread of automation. Moreover, urban life is more and more common and the number of inhabitants is rapidly growing. This time is the renaissance of bicycle-based vehicles, especially of electric power assisted bicycles. Vehicle sharing is also getting more popular. These progresses will have a crucial effect on traditional transportation networks. Moreover, the traffic volume, parking facilities and public space usage can be drastically modified. A research data is introduced from Paris and Lisbon, which helps to forecast the effect of the autonomous and sharing systems. This evolution can be advantageous, but it can also bring some disadvantages. In this article, these changes are summarized in the mirror of history, especially the Futurama concept and the transport system changes in Los Angeles. This overview will be a good basis for further research and for the development of a routing algorithm. |
Analysis of the Automotive Ignition System for Various ConditionsMatej Kucera, Milan Sebok, Matej Kubis, Daniel Korenciak, Miroslav GuttenCommunications - Scientific Letters of the University of Zilina 2020, 22(4):144-152 | DOI: 10.26552/com.C.2020.4.144-152 Paper presents diagnostic analysis of automotive ignition system for various working and adverse conditions in laboratory. Description and importance of basic diagnostics of automotive ignition system are examined in the first part of the paper. In the second the focus is placed on the basic principles and solution of the spark plug model. The test laboratory device is proposed in the following and the specialized measurements were executed by the proposed measurement system. The faults were simulated by application of oil and gasoline between the electrodes and failing by the driver to make the ignition contact on the spark plug. |
Influence of the Ionospheric Delay on Designation of an Aircraft PositionJanusz Cwiklak, Marek Grzegorzewski, Kamil KrasuskiCommunications - Scientific Letters of the University of Zilina 2020, 22(3):3-10 | DOI: 10.26552/com.C.2020.3.3-10 The article presents and describes research results concerning determination of an impact of the ionospheric correction upon the positioning accuracy of an aircraft. The main objective of examinations was to verify three ionospheric models (the Klobuchar model, SBAS model and IONEX model) in determining aircraft coordinates. In the framework of the conducted simulations, the authors determined the aircraft coordinates by means of the SPP code method in the GPS system. The article presents a comparison of the determined aircraft coordinates in the SPP code method in relation to an accurate solution in the RTK-OTF differential technique. Based on the obtained results, it was found that e use of the SBAS and IONEX model is exploited to improve the positioning accuracy of an aircraft in relation to the Klobuchar model, from 20% to 72%, in the geocentric XYZ frame. The obtained findings of a simulation indicate that the ionospheric correction in the SBAS and IONEX models may be used to improve the performance of aircraft coordinates in air navigation. |
Determinants of Labor Market in Jakarta Metropolitan Area: A Survival Analysis of CommutersIrwanda Wisnu Wardhana, Dhani Setyawan, KhairunnisahCommunications - Scientific Letters of the University of Zilina 2020, 22(2):42-51 | DOI: 10.26552/com.C.2020.2.42-51 This study aims to assess the determinants of the labor market in the Greater Jakarta Area (Jabodetabek) with a population of 27.9 million (2010 census) and growth rate of 3.6 percent per annum over the period 2000-2010. With a total area of 4,384 square kilometers (1,693 sq mi), the city has a very high population density of 14,464 people per square kilometer (37,460/ sq mi), while the metro area has a density of 4,383 people/sq km (11,353/sq mi). The paper employs the survival regression analysis by incorporating attributes of commuter, namely gender, age, distance, travel time, wages, stress, education level, double income households and home ownership. The area consists of Jakarta as the receiving labor market and eight municipalities and regencies as labor suppliers. The study utilizes a cross-section data from a commuter survey with more than 4,000 respondents participated using different modes of land transport. The results reveal that some determinants have influenced commuters' resiliency and their willingness to participate in the receiving labor market. This study found that gender, distance, wages and home ownership do not affect the respondent's decision whether to stay or quit as commuters. On the other hand, the fittest model exhibits that age, education level, stress, travel time and double income households have significant effects on individual's decision to stay or quit as a commuter. It is found that gender, distance, wages and home ownership do not matter for respondent's decision on whether to stay or to quit as commuters. The model exhibits that age, education level, stress, travel time and double-income household have significant effects on an individual's decision to stay or quit as a commuter. Education level has a positive effect; on the other hand, age, stress, double-income household and travel time have a negative effect. The policy implications for improving the labor supply provision and some contested policy options are suggested, such as the provision of affordable housing in Jakarta, the improvement of commuting enjoyment, the establishment of child care facilities in the office buildings and the creation of more sophisticated jobs within the Jakarta's surrounding municipalities and regencies. |
Effect of Tool Pin Length on Microstructure and Mechanical Strength of the FSW Joints of Al 7075 Metal SheetsAgata Wronska, Jacek Andres, Tomasz Altamer, Agata Dudek, Robert UlewiczCommunications - Scientific Letters of the University of Zilina 2019, 21(3):40-47 | DOI: 10.26552/com.C.2019.3.40-47 The Friction stir welding (FSW) is a complex process, depending on many factors: machine, clamping device, material and tools. Parameters that have a direct impact on the quality of the joint include the rotational speed, welding speed, clamping force, geometry and tool plunging depth. The paper presents the results of experimental studies concerning the effect of tool pin length on the microstructure and mechanical strength of joints of thin sheets made of Al 7075 alloy. A tool with an adjustable pin with concave shoulder was used to weld the joints. Different pin lengths were used, which were selected with respect to the thickness of the welded joint. The specimens were subjected to visual evaluation, metallographic tests and mechanical strength testing. The results indicate that the pin length has a decisive effect on the microstructural changes in the joint and thus influencing the strength of the FSW joints. |
Determination of the Precise Coordinates of the GPS Reference Station in of a GBAS System in the Air TransportKamil Krasuski, Stepan SavchukCommunications - Scientific Letters of the University of Zilina 2020, 22(3):11-18 | DOI: 10.26552/com.C.2020.3.11-18 This paper presents results of research concerning determination of the GPS reference station coordinates located on the grounds of an EPDE airport in Deblin. The study uses a mathematical model of the PPP measurement technique in order to determine the coordinates of the reference station using the real GPS code-phase observations. The computations of the coordinates of the GPS reference station were carried out in numerical applications CSRS-PPP, APPS and GAPS. In this research was found that the accuracy of finding solutions to the XYZ geocentric coordinates of the reference station REF1 between solutions CSRS-PPP, APPS and GAPS ranges from 0.01m to 0.13m. In addition, the accuracy of determining the XYZ geocentric coordinates from the PPP method related to the GPS differential solution ranged from 0.01m to 0.11m. |
Kazakhstan's Transit Potential Development through Transformation of Logistics Processes as a Part of Economic GrowthSayabek Ziyadin, Dimash Yergobek, Aigerim Kazhmuratova, Aigerim KuralovaCommunications - Scientific Letters of the University of Zilina 2020, 22(4):56-62 | DOI: 10.26552/com.C.2020.4.56-62 The rapid development of transport, the widespread introduction of modern transport technologies, close cooperation with Russia, China and other neighboring countries, will allow Kazakhstan to become a serious player in the transportation market between Europe and Asia in the coming years. Such existing transport potential directly affects the economic growth of the country which will lead to high living standard. The global movement towards digitalization is transforming the logistics industry, as well. The "digit" changes the channels of movement of goods, delivery formats and management processes. Development of e - commerce and the increasing supply requirements - multichannel, responsiveness, transparency, accuracy - stimulate retailers and logistics operators to increase efficiency of processes and introduce new technologies. Therefore, the ways of prosperity of Kazakhstani economy, through digitalization of logistics processes is considered in this article. |
