Table of Contents


    • Advantages of using composite materials in automotive manufacture process

      pg(s) 3-5

      The advantages of using composite materials are currently manifested in various industries. This creates space for their even greater application in the automotive industry. Car manufacturers strive to constantly reduce the weight of the car, increasing its durability and safety at the same time. Car consumption and associated emissions are closely monitored. Composite materials therefore offer a range of properties that meet today’s automotive requirements to a large extent.

    • On electromagnetic actuator control in the active suspension systems

      pg(s) 6-9

      In the paper, the design of a linear motor as an actuator in vehicle active suspension systems will be presented. The attention is focused on several interesting design aspects of a non-traditional actuator (a linear synchronous permanent magnet motor with electronic commutation) controlled to obtain a variable mechanical force for a car active suspension. The main advantage of such a solution is the possibility to generate desired forces acting between the unsprung (wheel) and sprung (car body) masses of the car, providing good insulation of the car sprung mass from the road surface disturbances. In addition, under certain circumstances it is possible to reduce or even eliminate the demands concerning the external power source.

    • Some approaches to the non-destructive control of composite materials used in the aerospace industry

      pg(s) 9-12

      One of the priority areas for the use of composite materials is the aerospace industry. A number of evaluations have shown that their use in the manufacture of modern aircraft and helicopters lead to a reduction in weight of the respective parts with 20-30% compared to the same manufactured from conventional materials. In this case, an increase in the resistance of the respective part to external influences is usually achieved, and in many cases a decrease in its production cost.
      The increasing use of composite materials in the aerospace industry requires analyzing options for their diagnosis and non-destructive examination of their quality, taking into account their specific features. Because of the enormous diversity and complexity composition for composite materials, various methods of diagnosis have different efficiencies for different types of composites. In many cases, composites contain highly porous or fibrous layers, which results in a strong attenuation of the acoustic waves and render the acoustic method inapplicable to their non-destructive control. In these and other cases, the use of emerging methods for their non-destructive ultra-high frequency (microwave) diagnostics is of interest.


    • Size and speed of data generated by Fleet Management Software

      pg(s) 13-16

      The paper looks at the relation between the number of transport domains (cars, trucks, buses, ship, etc.) and the size of data, generated in fleet management software. Nowadays, such software is stored and run on a cloud and users do not need to care about the size limitation, just for the price. If using a solution on premises, the cost includes creating and supporting infrastructure and licences. Software developers should care for the scalability of the application time and also managing bottlenecks, that are likely to appear in data flow due to the size of the management program.

    • Analysis of the causes that generate traffic accidents

      pg(s) 17-19

      The article describes the causes of serious road accidents, as well as the analysis of the influence of the environment on the safety in circulation. In addition, the road network schemes are subject to analysis, ie to what extent they influence the safety of the road. The geometric elements of the road, the layout, the curves in profile. The route of a road has to provide good guidance through its geometry in space and through the elements in the environment and the longitudinal profile, transversal profile, intersections, visibility analysis during the driving process of a vehicle. Influence of road function on traffic safety. For developed countries, the road network is defined on the basis of the road classification in terms of the function it performs, with a focus on the ability to collect or transit traffic. Influence of road equipment on traffic safety. Influence of running surface characteristics on traffic safety. The ruggedness, flatness and waterproofness of the road surface are absolutely indispensable, ensuring the comfort and safety of the traffic. The influence of the human factor on the safety in circulation. Traffic participant is the first link in the road safety chain. Whatever the technical measures adopted, the effectiveness of road safety policy ultimately depends on the behavior of the traffic participants. Violation of pedestrian traffic rules. The circulation of the means of transport is accompanied by energy waste, in the form of noise and vibration, which also has an influence. The forecasts for the development of the transport network show that the sudden increase in the number of transport units increases the risk of an increase in the number of accidents. The vehicle, its influence on the safety in circulation. According to the data on the distribution of accidents by types of vehicles, we can see that the group with the highest number of accidents is that of cars. Conclusions and recommendations are outlined.

    • Geometric parameters in railroad crossing based reconstruction of Iliantsi-Curilo and Curilo-Rebrovo

      pg(s) 20-22

      Railroad crossings are a point of conflict between rail and road transport. Failure to abide by the rules and their malfunctioning leads to human casualties. The solution is to improve transport infrastructure. In the course of renewal of the railways in the form of rehabilitation, reconstruction, emergency repairs, new construction and more, it is inevitably necessary to intersect road infrastructure. This is done by crossing at one or two levels. During the construction of the main railway lines in Bulgaria, the safety requirements, the load of the road infrastructure, the current speeds, the financial possibilities and other factors led to the construction of many railroad crossings 757 [1]. They are on the secondary and major railway lines, especially outside the large settlements.
      Of course, with the construction of new routes, intersections at two levels are envisaged and constructed [2, 3], but at the same time the railroad crossings on the rest of the railway network requiring higher safety criteria have to be maintained. This necessitates the replacement of many elements of the railway and the pavement [4], which in turn leads to a change in the conditions for the reconstruction of the railroad crossings. The report examines a specific case of construction practice – reconstruction of railroad crossings along the second railway line in the area of Iskar Gorge [5], but the conclusions it requires are valid for most existing railroad crossings.

    • Researching of the factors determinant safety movement of the train in braking regime – impact of braking force on the superstructure of the railway with regard to the interoperability and the experience of the railway section Gorna Oriahovitsa

      pg(s) 23-25

      The horizontal reaction of the rail is very important to the creation of the braking force. The value of rail reaction is equal to the value of the braking force. The subject of the article is the determination of braking force in two different ways. The first is based on braking pressure for one braking jay and friction between braking jay and wheel for vehicles equipped with block brake. The second is based on braked weight and braked weight percentage. The theoretical results obtained by the two methods are compared on the basis of the need for interoperability under Regulation 1299/2014 relating to Infrastructure subsystem of the rail system of the EU. The practical impact of braking force in declivities with a gradient of slope over 15 ‰ has been established on the basis of direct observations and analyzes. The experience in the operation of heavily inclined sections of the Gorna Oryahovitsa railway section has been used.


    • The change in energy flow streams for main marine propulsion steam turbine at different loads

      pg(s) 26-29

      This paper present analysis of energy flow streams through the main steam turbine (the turbine is used for commercial LNG carrier propulsion) at three different loads. An increase in the propulsion plant (and proportionally increase in the main turbine) load resulted with an increase in energy flow streams and with an increase in the amount of water droplets inside steam at the main turbine outlet. Analyzed turbine has three steam extractions which opening as well as the amount of energy flow stream delivered through each extraction, significantly differs at various loads. The analysis shows that the highest energy flow stream consumers from the main turbine are deaerator and high pressure feed water heating system.

    • Methodology for static tuning of the HEV fuel flow measuring system

      pg(s) 30-33

      The modern automobiles are subject of more stringent requirements [1] corresponding to power, torque, fuel economy and ecology legislations, which is led to designing of new power sources and constructions, such as the hybrid electric vehicles (HEV). They are moving by the energy [2], which is ensured by the internal combustion engine (ICE) and the battery. The main factor in this area is the HEV fuel system, which is controlled by the electronic control unit (ECU) [1]. The electronic control of the Spark Ignition Engines (SI engines), as well as the Direct Ignition Engines (DI engines) is based on the certain sensors signals, program maps and management algorithms. The result in this electronic control is the management of the fuel injectors. The management of the fuel injectors consists in the start of injection, injection duration, number of injection events, injection advance, injection pressure etc. Moreover, the fuel consumption and fuel efficiency are the main factors, which are determining the HEV advances. The learning and measuring the HEV fuel consumption, as well as, the conventional automobiles, is the ground for achievement of quality results in the education of the automotive engineers, as well as for obtaining of scientific researching for developments and innovations. Significant meaning in this concept has the real, live and practical performance with the help of testing equipment and test-benches. This paper renders the methodology of static tuning the Fuel Flow Measuring System EFMS100 on the test bench SAV-1 with the support of controller Matrix MIAC MI0245 and Flowcode 7 software.

    • Investigation of the influence of fulleren-containing oils on tribotechnical characteristics

      pg(s) 34-37

      The influence of fullerenes’ soot concentration, which added to oil М10г2к on few tribotechnical characteristics «steel-steel» was investigated. It was found, that optimal volume of fullerene soot in the oil was 0,1% of the weight. At this level of concentration can be seen the lowest values of coefficient of friction – 0,045, and intense of linear wearing – 2,7×10-9. Through optical investigation the participation of fullerene soot in surface forming mechanism and saturated with carbon was confirmed, it provided an increase in tribotechnical characteristics of the samples.