International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

During exploitation wagons must fully implement the transportation process safely. Wagons spend their own technical resources in the process of exploitation, and therefore they need to be restored. During the process of moving, accumulated defects in the moving part, axle boxes, brake equipment and in other knots of wagons, and the number of failures in wagons depend on the reliability of the construction and on the quantity of kilometers that the wagons have run.

This scientific report focuses on investigating the influence of geometric design on ship ventilation flow efficiency through numerical simulation with ANSYS. Many sources on the subject state that in a ship’s ventilation system, the flowing fluid encounters various devices and fixtures such as valves, fans, and bends that can cause sudden expansions or contractions of the flow. These geometric factors cause energy loss, which can be of importance to the efficiency of the ship’s ventilation system, especially in the complex conditions of power generation. Such energy losses are considered significant in these industries and are the subject of serious design and optimization of flow systems. Using engineering simulations, this report investigates steady laminar flow through a pipe with sudden expansion in order to understand and predict the energy losses resulting from the expansion. The practical example of application can be the analysis of the ventilation system of a ship, where such geometric designs can affect the efficiency of the ventilation and therefore the performance and safety of the crew and passengers. Such research is essential to improve the manufacturing and operational processes of ships and to ensure their optimal working conditions.

An important aspect in organizing acoustic emission monitoring is the analysis of recorded data and selecting useful information. Despite noise suppression using frequency methods, its quantity in the recorded information can reach 99% because the process of degradation during operation typically progresses slowly, whereas the presence of acoustic noise is an inherent attribute of the technological process.
Noise suppression after data recording is carried out within the framework of the monitoring system’s software, although filtering algorithms may be specific to each application.

The use of video cameras for automatic traffic management, as well as video surveillance cameras, has made it possible to visually observe traffic accidents, i.e. the manner and movement of the parties involved in the accident at the moment and immediately before it occurred. On the basis of a video of a vehicle passing through a section that can be photogrammetrically rectified and transformed into an orthogonal view, with knowledge of the dimensions of characteristic formations that are usually rectangular in shape, such as pedestrian crossings, etc., and with knowledge of the frequency of the video recordings, it is possible, using appropriate software, to determine the speed of the object under study. In this paper, the reliability of the speeds determined by rectification using the AnalyzerPro software has been compared with the target speeds of the vehicle defined by the speed limiter, measured by a handheld radar and a GPS device installed in the vehicle.

This paper presents results of the Main Feedwater Pump (MFP) isentropic and exergy analyses at three power plant loads. Observed MFP is a constituent component of condensate/feedwater sub-system from conventional steam power plant. In real exploitation conditions, MFP uses mechanical power higher than 3000 kW, considering all observed power plant loads. Main isentropic and exergy parameters of the MFP at various plant loads show the same general trends (increase in power plant load simultaneously increases MFP losses and efficiencies and vice versa, from both isentropic and exergy viewpoints). Analyzed MFP has high isentropic and exergy efficiencies, considering all plant loads and ambient temperatures (at any plant load MFP isentropic efficiency is higher than 85%, while the lowest MFP exergy efficiency is equal to 89.24% at the lowest observed plant load and the highest observed ambient temperature). The change in isentropic and exergy efficiency of the MFP is small if all observed plant loads and ambient temperatures are taken into consideration.

Turn signals are an important device on vehicles, with which we inform other participants about our intention when changing lanes, realigning, turning, overtaking, etc. The use of turn signals increases the safety of all road users. According to research conducted in the USA and Canada, one of the reasons why drivers do not use their turn signals is that they sometimes forget to turn off this device. In this work paper, special emphasis is placed on determining the position of the steering wheel at which the automatic turning off of the turn signal is activated when returning the steering wheel to the original “zero” position, as well as the position of the steering wheel when the automatic turning off of this device is not activated.

Regardless of the fact that all the prerequisites exist for the development of maritime business and shipbuilding in Bulgaria, a purposeful state maritime policy has not been implemented for a long time. Although there are registered beginnings of our shipbuilding already at the end of the 19th century, and the first serious orders were made during the Second World War, one can speak of a Bulgarian state policy of shipbuilding only in the 2 ½ of the 20th century. Until 1962, the development of the shipbuilding industry was at an average level for the capabilities of our country. In the following decades until the end of the socialist period, shipbuilding emerged as a sub-branch of machine-building of strategic importance for the entire industry, and the scale of its development was comparable to the scale of countries with developed shipbuilding. It is characteristic of the entire period that the majority of shipbuilding production is not created for internal needs, but is dictated by external orders, structural changes are constantly made in the management, there is a lack of continuity, and the construction of capacities for the construction of large-tonnage ships takes a very long time time is a debatable issue. Nevertheless, the development of the shipbuilding industry brings enormous positives to the country. During this period, Bulgaria was recognized as a maritime country; builds a production and technical base that is not small for the scale of our country; puts the work on a scientific basis and gives an opportunity for the appearance of a whole constellation of engineers, according to whose projects dozens and hundreds of ships that sail under the Bulgarian and foreign flags have been built.

The present research paper examines the thermal conduction transient through a 2D model analysis using the Ansys Mechanical software product. The study focuses on the importance of time in the heat conduction process and its influence on temperature stabilization in various materials and structures. Any process related to heat transfer requires some time to reach a stable heat conduction state. In various scientific and engineering fields such as thermal engineering, electricity generation, and electronics, understanding, controlling, and analysing transient conductivity can lead to more efficient operation of machines and mechanisms, reduction of energy costs, development of more resistant materials, optimization of conditioning systems, and creation of engineering simulations and models to predict thermal behaviour under different conditions. In addition, the present study can provide new knowledge in the educational field and serve as a basis for a new approach in teaching in the field of thermal engineering regarding the clarification of the conditions under which heat exchange processes occur and related changes.

In the world today, Germany could lose its status as a superpower in the automotive industry, and the German Association of the Automotive Industry considers excessive regulation, slow political decisions and the absence of a legal framework for issues such as artificial intelligence as key problems.
From the year 2021, the list of Chinese companies has doubled. China develops electric motor cars and has taken the lead compared to Europe, especially in battery technologies, but also subsidizes their production. At the same time, China became the world’s largest car exporter in 2023 – it exported 4.91 million cars, which is an increase of 57.9% compared to the last year, becoming the world’s first country according to the number of exported cars.
An additional problem for car manufacturers is created by the European Union’s plans to phase out vehicles with internal combustion engines by 2035. There is also a lack of access to the raw materials needed to manufacture batteries and the slow development of electric vehicle charging infrastructure. Nevertheless, during the year 2023, 254 thousand “Tesla” models were sold in Europe, making this car the best-selling car on the continent.
From July 2024, every new car must have the most modern safety systems, having in mind that 20.400 people died on the roads of the European Union in 2023, according to unofficial data (that’s 1% less than in 2022). From July 7, new cars are obliged to have 10 additional safety systems, which will contribute to increasing safety and reducing the number of accidents.
On the territory of Serbia, a license was issued to one company for test driving of automated vehicles, after tests and analysis conducted jointly by the Traffic Safety Agency and the CIAX laboratory of the Faculty of Mechanical Engineering in Belgrade. And from
February this year in Serbia, the registration of those interested in state subsidies for the purchase of electric vehicles began and will continue until October. In Kragujevac, from 2024 “Stelantis” will start producing the new “Panda” hybrid. It was announced that it will be called “PANDINA”. And we look forward to its production.

The main feature of modern earthmoving machines is the execution of a wide range of different operations. At the same time, the loading mode changes and it is characterized by coordinates, values of the applied forces acting on the machine and the regularities of their change in time. In order for the machine to be able to adapt to the listed variables, it must be equipped with the appropriate systems. Existing calculation methods do not allow taking into account the entire range of these effects. In the proposed work, adaptation approaches of earthmoving and transport vehicles to variable operating conditions are analyzed.

The article is focused on the study of the integrity of the material that is used in the automotive industry in process of creating joints by combined technology. The article describes the study of the properties of chemically pretreated surfaces by phosphating technology. When creating new surfaces by phosphating, a new type of phosphate layer was used using modern conductive compounds of polyaniline salts. The pretreated surfaces were investigated in terms of structure, 2D and 3D microgeometry, contact angle in relation to the determination of surface wettability and surface energy. The experiment was realized in order to identify the connections between individual factors of the process and roughness characteristics.

Paper deals with a newly designed three-phase asynchronous electric motor with an application as a traction motor for driving compact battery-powered electric vehicles mainly in urban environments. The main characteristics of the motor are presented. The problems and solutions related to the sizing and optimization of the motor in the design according to various criteria and conditions are analyzed, with energy efficiency being the main determining factor.