Scuffing is a spontaneous gear failure mechanism resulting in a disrupted surface. Scuffed gears are more sensitive to dynamic excitation and friction. Besides the lubricant and the material, the scuffing load capacity is mainly dependent on the gear geometry. High contact ratio gears exhibit a lower load carrying capacity due to an increased dissipation of frictional heat in the outer mesh positions. In this paper this phenomenon is addressed with experiments and simulative analysis. Based on these works, recommendations for adequate profile modifications are derived to maximize the load carrying capacity regarding scuffing of high contact ratio gears.
Trans Motauto World
Vol. 7 (2022), Issue 3
Table of Contents
TRANSPORT TECHNICS. INVESTIGATION OF ELEMENTS. RELIABILITY
In the proposed publication it is conducted simulation-based experiment with the bunkering process of type “C” LNG containing tank. According to the specific features of the LNG bunkering process it is analysed the nature of the boiling off mechanism of the cryogenic fluid during bunkering transfer. The attained data by the experiment is analysed including the specific condition of heat ingress simulation. On the base of the results there are stated conclusions and recommendations to the ship operators related to the limiting conditions of the pressure vessels operation as it is the type “C” tank.
The majority of railway projects in our country aim at the maximum utilization of existing railway infrastructure, increase of the operation parameters, frequently at the condition of achieving interoperability. Increasing permissible speeds of trains invariably requires increasing the radii and lengths of curves. However, at small delta angles the use of the minimum design speed radius gives suboptimal results in terms of the total length of the curve. The report presents a parametric method for optimizing the railway curves at small delta angles in view of the necessity of achieving higher speeds on existing lines.
Generally, passenger ride comfort can be interpreted as an attenuation of sprung mass acceleration or as peak minimization of sprung mass vertical displacement, while good handling can be characterized as an attenuation of unsprung mass acceleration. This effort devoted to passive suspension design is ineffective because improvements to ride comfort are achieved at the expense of handling and vice versa. Instead, the best result can be achieved by active suspension, i.e. when an additional force can act on the system and simultaneously improve both of these conflicting requirements. Another important goal of the control design is to maintain robustness of the closed loop system. In the paper, fuzzy logic is used to simulate active suspension control of a one-half-car model. Velocity and acceleration of the front and rear wheels and undercarriage velocity above the wheels are taken as input data of the fuzzy logic controller. Active forces improving vehicle driving, ride comfort, and handling properties are considered to be the controlled actuator outputs. The controller design is proposed to minimize chassis and wheels deflection when uneven road surfaces, pavement points, etc. are acting on tires of running cars. As a result, a comparison of an active suspension fuzzy control and a spring/damper passive suspension is shown using MATLAB simulations.
TRANSPORT. SAFETY AND ECOLOGY. LOGISTICS AND MANAGEMENT
The analysis of each traffic accident is carried out based on recorded traces at the scene of the traffic accident and the damage caused to vehicles. One of the basic parameters in the analysis of traffic accidents is the mutual position of the vehicle at the time of the collision. To define the collision position of the vehicle, it is necessary to determine the intensity and compliance of the vehicle damage. The development of photogrammetry has enabled the creation of 3D models based on which the intensity and mutual compliance of vehicle damage can be more clearly shown, which increases the relevance of the determined collision position of the vehicle. Accordin gly, this paper will present the process of creating 3D models of damaged vehicles and will analyze all the possibilities of applying photogrammetry in defining the collision positions of vehicles.
The greater interest of people living in urban areas has been accompanied by an increase in demand for motorized movements and other forms of active movements in these areas. As a result, traffic problems have been increased extremely for these road users both in terms of the quality of movement and safety. This research is focused on identifying factors related to the quality of motori zed and nonmotorized movements in urban areas, a particular case study of the municipality of Fushe Kosova, and the design of a model for traffic optimization in urban areas. The current approach to prioritizing the solution of motorized traffic problems, especially in d eveloping countries, has proved ineffective because, in the absence of addressing other mobility requirements (pedestrian, cyclist mobility), road users have been encouraged more to use this form of transport, leaving no room for other alternatives. The research aims to apply advanced methods for handling and managing traffic problems based on the principle of inclusion and building a model for optimizing traffic operation based on a specific case. The model is built using the programming language “Synchro,” which enables the analysis, optimization, and simulation of all forms of transport: motorized traffic, movement of pedestrians and cyclists in the road network planned following these requirements. Obtained results show the advantages of using different forms of transport depending on the selected concept and the priority of certain forms of transport. The summary results and their comparison in terms of quality for different time intervals, including the different conditions of access to urban areas, are presented in tabular forms.
This article analyzes examples of good traffic management practices in several European cities. The practices analyzed relate to providing more accurate information about public transport arrivals, optimizing demand for crosswalks, reducing congestion in urban areas, and reducing demand for trips to parking lots in the city center. Smart mobility projects such as CEKOM Connected Traf fic create high-quality urban transport solutions and promote innovative, sustainable, clean and energy-efficient transport modes. The aim of this paper is to present the positive results of different traffic management methods that lead to better traffic flow, less congestion, lower primary energy consumption and less pollutant emissions.
The activities of this scientific research project are related to the development of innovative urban and multimodal solutions in the city of Rijeka. The primary outcome indicator will be a platform for aggregating data for urban mobility and transport decision making. The scope of the platform envisions more efficient use of public-private infrastructure, resources, and assets in the field of transport. In addition, it was necessary to accurately measure traffic, meteorological and environmental parameters in the city of Rijeka to protect the environment, increase safety and achieve sustainability of the transport system in the urban area.
As part of the research activities of the Connected Traffic project, a prototype solution for traffic simulations has been developed. The aim of the simulations is to show how the use of innovative methods in the context of intelligent solutions can manage traffic in urban areas. The purpose of the simulation is to test innovative scenarios and standard operating procedures for decision support.
The activity of snow removal on public roads is of particular importance for ensuring road transport in winter and implicitly for maintaining a stable, predictable and efficient economic and social climate. The organization of road snow removal is usually done by the local public authorities, through the public road administrator, varying depending on the geographical and climatic location of the road site. In Romania, the snow removal activity is regulated by the “Regulation on preventing and combating snow on public roads”, indicative AND 525-2013, developed by the National Company of National Highways and National Roads in Romania. The snow removal activity is usually performed on the basis of a service contract and is temporary, depending on the evolution of meteorological phenomena and climatic zones.
The actions to prevent and combat the consequences of dangerous meteorological phenomena are carried out according to their intensity on the following phases, as follows: prevention of icing formation and its neutralization, spreading of anti-skid material and snow removal. The preventive spreading of the anti-skid material is recommended to be done first on the entry / exit arteries in / from the localities. The activity of mechanical cleaning of public roads (streets, bridges, alleys, roundabouts) of snow with blade machines is performed when the snow layer exceeds the thickness of 5 cm. The activity is carried out by successive passages, starting from the axis of the road to the curb, until the complete removal of the snow layer.
A prototype of a system for segmenting images of trains and wagons has been developed. Video cameras and specialized websites are used as the source of the original images. Median filtering of images and increase of their local contrast is carried out. The contours of the objects were calculated using the Sobel and Canny methods. Image segmentation is performed by the method of contour lines. As a result of the processing on the images of trains and wagons, meaningful areas (segments) were identified, for example, windows, headlights, etc. Detection of content areas of the object is performed using fuzzy membership functions. The hardware and software implementation of the computer system is made in Python using scipy and scikit-fuzzy libraries, the Google Colab cloud platform and Raspberry Pi 3B+ microcomputer.
The occurrence of road accidents due to a pavement surface with inadequate roughness is an alarming issue. This problem involves not only the design, construction and maintenance of road pavements, but also the properties of the materials used in the asphalt mixes, traffic volume and vehicle speed, as well as tire characteristics, human factors, environmental conditions and many other contributing elements. As a result, there is a growing awareness of these problems and adequate measures have to be taken by road administrations in order to improve traffic safety. For the design, construction and maintenance of a modern road network, along with strength and sustainability, skid resistance has become an integral part of a safe and efficient road system. With the increase in traffic speed and volume, the road pavements built today must have initial and continuous qualities of high skid resistance. It is a well-known fact that the pavements skid resistance is reduced primarily by mechanical wear and polishing due to traffic action; however, to what extent the friction characteristics are diminished and the other causes and effects of this reduction are problems that road engineers have to face. Although the automotive and tire industries have contributed greatly to the research and development of skid-resistant road pavements, it is quite obvious that most of the improvements will go to pavements. In the following, the paper will focus on establishing the roughness criteria that can be applied from the early stages of the construction of a road infrastructure, by selecting those materials and techniques that lead to a high level of roughness and thus traffic safety. Also, the paper presents the results of recent experimental studies undertaken to determine the road roughness, using the microtexture as well as macrotexture criteria, conducted in Romania on the national roads DN 2 km 212 + 000 and DN 15 km 290 + 870.
VEHICLE ENGINES. APPLICATION OF FUELS TYPES. EFFICIENCY
Damage to the turbocharger of the 8400kW diesel engine, which had operated about 66 640 running hours, has caused off hire of the vessel for 10 days and the turbocharger repair had cost more than half a million euros. The study performed on this work consi sts of evaluating the consequences of the low turbocharger performance on the fuel oil consumption and the reasons for this. Specific data were collected and analysed in order to create an appropriate mathematical model between the studied parameters. Measurements and data collected were performed a month before turbocharger damage and after the TC overhaul (with new cartridge). As results can be concluded that losses in turbocharger performance is very important for the efficient operation of the main engine, they must be monitored and analysed.