Trans Motauto World
Vol. 6 (2021), Issue 2

Table of Contents

  • TRANSPORT TECHNICS. INVESTIGATION OF ELEMENTS. RELIABILITY

    • Exergy analysis of three cylinder steam turbine from supercritical coal-fired power plant

      pg(s) 34-37

      In this paper is performed exergy analysis of three cylinder steam turbine from the supercritical coal-fired power plant. Exergy analysis parameters were calculated for the whole turbine and each cylinder for the ambient temperature range between 5 °C and 45 °C. The dominant mechanical power producer of all the cylinders is a low pressure cylinder (LPC) which produces 262.06 MW of mechanical power. An increase in the ambient temperature increases exergy destructions and decreases exergy efficiencies of the whole turbine and each cylinder. Exergy analysis shows that LPC is a cylinder with the highest exergy destruction (between 24.67 MW and 28.24 MW) and the lowest exergy efficiency (between 82.27% and 84.16%) in comparison to the other cylinders. Exergy destruction of the whole observed turbine is between 67.85 MW and 77.62 MW, while the whole turbine exergy efficiency ranges between 89.47% and 90.67%. Inside the observed steam turbine, LPC is the most influenced by the ambient temperature change, therefore future research and possible optimization should be specifically based on this cylinder.

    • Scissor lift dynamic analysis and motion regulation for the case of lifting with maximum load

      pg(s) 38-42

      This paper deals with Dynamic analysis of Scissor Lifts during the Load Lifting to determine their dynamic behavior, find the nature of oscillations, and the regulation of lifting to minimize these oscillations and optimize the work process. During the motion processes, the lift and its main parts undergo heavy forces, moments, and oscillations. The method of research is acquiring results through design, modeling, and simulations, comparing them with analytic calculations, and looking for the optimal motion regulation of the Load Lifting. The analysis will be acquired when the Scissor lift is carrying maximum Load. The study will be concentrated in the finding the nature of dynamic forces and stresses that acts on the main parts of the lift and the extent and the form of oscillations. Results will be shown in the form of diagrams and contour views as the solution results of the tested system. Modeling and simulations will be carried using software SimWise 4D, based on the type of the Scissor Lift taken from Standard Manufacturer. Conclusions of these analyses are useful for design considerations, dynamic behavior, and safety of these types of lifts.

    • Experimental Results of the Hybrid Electric Vehicle Energy Efficiency in Urban Transportation

      pg(s) 43-46

      The development of internal combustion engine vehicles, especially automobiles, is one of the greatest achievements of modern technology. Automobiles have made great contributions to the growth of modern society by satisfying many of its needs for mobility in everyday life. The automotive industry and the other industries that serve it constitute the backbone of the word’s economy and employ the greatest share of the working population. However, the large number of automobiles in use around the world has caused and continues to cause serious problems for the environment and human life. Air pollution, global warming, and the rapid depletion of the Earth’s petroleum resources are now problems of paramount concern [1]. A hybrid vehicle combines any type of two power (energy) sources. Possible combinations include diesel/electric, gasoline/fly wheel, and fuel cell (FC)/battery. Typically, one energy source is storage, and the other is conversion of a fuel to energy. The most modern hybrids are powered by a combination of traditional gasoline power and the addition of an electric motor. However, hybrid still use the petroleum-based engine while driving so they are not completely clean, just cleaner than petroleum only cars. This enables hybrid cars to have the potential to segue into new technologies that rely strictly on alternate fuel sources [2,3].
      This paper considers the experimental result obtained from HEV energy efficiency researching in urban transportation in the town of Sofia.

    • Design of a sailplane based on modern computational methods

      pg(s) 47-50

      The purpose of the current study is to evaluate and apply a new approach to the design process of an aircraft with a high aspect ratio wing, based on modern understandings and development in the fields of aerodynamics and computational fluid dynamics. Conventional methods rely on semi-analytical models for describing different flow characteristics and interactions with bodies. The classical approach requires numerous coefficients to account for unknown effects, what is more, such workarounds are derived for well-defined cases and are not easily applicable for complex problems which could be dangerously misleading. CFD analysis, based on new developments in computational machines, give the possibility of analyzing complex aerodynamic interactions such as shading, downwash, ground effect and vortex shedding. Such use of innovative technology has already proven itself to have beneficial effect on reduction of cost a nd human error by being able to simplify and speedup many of the calculations without the need of coefficient adjustments.

  • TRANSPORT. SAFETY AND ECOLOGY. LOGISTICS AND MANAGEMENT

    • Characteristics and state of road traffic safety in Montenegro

      pg(s) 51-53

      The subject of research in this paper is the analysis of road traffic safety in Montenegro. Road traffic safety in Montenegro is not at an enviable level. The number of traffic accidents on the territory of Montenegro has been constantly increasing in the la st few years. The state of traffic safety in Montenegro differs significantly from most EU countries. In the last few years, Montenegro has made great efforts to improve road safety. Infrastructure is being improved, technical inspections of road vehicles are being tightened, and a larg e number of campaigns have been done to improve road traffic safety

    • Common dimensions of European transport policy and the “Belt-Road” initiative

      pg(s) 54-56

      China’s stated objectives for the Belt and Road Initiative (BRI) refer to a broad intention to foster international collaboration with the countries involved, which focus on capacity building, liberalisation and facilitation of trade and investment, financial cooperation and people-to-people exchange. All of them are closely related to policies. According to our opinion, the most outstanding are the logistics objectives for the BRI, in order to support Chinese exports of products and equipment, as well as its engineering and construction capabilities and technologies and controlling logistics chains with Europe. Among the other not less important objectives is the necessity of balanced development across China.

    • Modeling travel behavior onboard of privately autonomous vehicle and shared autonomous vehicle

      pg(s) 57-61

      The impact of travel time, travel cost, and multitasking availability on the selection of privately use AV (PAV) and shared AV (SAV) are examined. The main daily trip is only studied, where all trips are within urban areas. A stated preference (SP) survey which includes a discrete choice experiment, was designed and distributed in Budapest, Hungary to collect the preferences of people towards PAV and SAV. As a result, a sample size of 2056 observations was obtained from the survey. A discrete choice modeling approach was applied to the data using a conditional logit (CL) model, where the characteristics of the alternatives are considered. The analysis results show that the value of travel time (VOT) of SAV is lower than AV, and the probability of choosing a transport mode is increased when multitasking is available in a transport mode. Moreover, the impact of travel cost on transport mode choice is higher than the impact of travel time. In conclusion, people are more likely to select SAV over PAV when the multitasking availability is considered as one criterion in the transport mode selection.

    • Determination of pre-collision travel speed in the event of a frontal collision between a vehicle and a fixed obstacle, using video recordings

      pg(s) 62-64

      The present paper evaluates the pre-collision travel speed of a road vehicle, in the event of a frontal collision with a fixed object such as a pole. In this regard, the method of video recordings and image processing using Tracker software program is used. In order to validate the proposed method, the obtained results are compared to the ones acquired with the use of accelerometers mounted on the inferior surface of the vehicle’s body. These accelerometers provide a series of real data during the time of the crash, which are then processed in order to reduce the anomalies that appear as a consequence of external factors such as vibrations or signal interferences.

    • Ride comfort in road vehicles: a literature review

      pg(s) 65-69

      Passengers and the driver in vehicles are subjected to vibrations, noise, acceleration, etc., which affect the comfort, activity and health of people. The effect of vibrations on the human body depends on their frequency, amplitude, duration and direction of impact. Prolonged exposure to vibration causes fatigue in the driver and passengers, which reduces their performance and worsens their functional condition. This can affect traffic safety, so one of the main requirements for modern vehicles is to increase ride comfort. The ride comfort is a set of conditions, impacts and sensations of the driver and passengers when traveling in vehicles. Over the years, there have been many
      studies and scientific developments aimed at measuring, evaluating and analysing the various factors that affect ride comfort . This paper presents a review on the research studies that have been done on dynamic factors that affect the ride comfort in road vehicles and methods used for measurement and its evaluation were discussed. Finally, some existing suggestions for improving the ride comfort in road vehicle are presented.

  • VEHICLE ENGINES. APPLICATION OF FUELS TYPES. EFFICIENCY

    • Fuel economy of off-road vehicles in respect to recuperation of vehicle’s kinetic energy

      pg(s) 70-73

      Since the fuel-saving idea was introduced in the 20th century, energy efficiency has gained attention in the transport industry. Ground vehicles (military, agricultural, and construction) usually operate on unprepared ground and need to overcome very complex and difficult ground obstacles, such as steep grade and very soft ground. The electrification of conventional vehicles, ranging from passenger vehicles and trucks to ground vehicles such as agricultural tractors, construction equipment and military vehicles, can poten tially offer improvements in fuel economy and emissions. Applied new systems reduce the amount of mechanical energy needed by the thermal engine by recovering the vehicle kinetic energy during braking and then assisting torque requirements. Energy management strategies for off-road vehicles are studied in this paper. With heavily fluctuating fuel prices, the total cost of ownership of loaders, excavators, and other classes of ground vehicles is nowadays strongly influenced by the fuel costs and there is growing concern about CO2 emissions as well as about the long-term availability of fossil fuels.