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

This paper describes the design and practical implementation of AC/DC/DC converter in mode of arc welding. An analysis of the operation of AC/DC/DC converter and its input/output characteristics are determined with computer simulations. The practical part is con- sisted of AC/DC/DC converter prototype for arc welding with output power of 3 kW and switching frequency of 64 kHz. The operation of AC/DC/DC converter is validated with experimental measurements.

An alternative method for kinematic and power analysis of compound gear train is presented, which uses the torques and lever analogy of a given gear train. The method combines the accuracy of the Willis analytical method with the clarity of the graphic method of Kutzbach. Unlike these methods, the torque method allows determining not only the gear ratio, but the magnitude and direction of power flows, and hence the determination of efficiency of a given compound planetary gear train. The application of the method is illustrated with example of complex change-gear (gear-box).

This paper presents performances of two different types of PV cells under various temperature clime of Stip, R. Macedonia.
Stip with geographical position 41 .742N, 22.1 94E has 2260 sun hours yearly with average temperature 25 °C during spring.
The types of cells examined in this study are: crystalline silicone (c-Si) and polycrystalline silicon (p-Si). The calculations are made for various operating conditions and a comparation of I-V and P-V characteristics are represented here. Also, the efficiency and fill factor for photovoltaic (PV) cells is calculated based on simulation results.

In this paper analysis of power converters with parallel resonant circuit by using of computer simulations is made. The full bridge IGBT power converter is analyzing. The simulations are made in PowerSim simulation program. Calculation is the efficiency of the converter and is made harmonic analysis of the output voltage and current. Also, is made and compare on the obtained results of the parallel resonant converter with the results of the serial resonant converter in applications with variable RL-load.

E-learning, seen in the ergonomic aspect, is a complex and intense human activity that is subject to investigation and analysis in order to optimize it. The quality of education is seen as a trinity of its effectiveness, efficiency and satisfaction – criteria that are defined, studied and assessed using a specially developed, original methodology of the authors. These criteria were used to investigate BA, MA and Ph.D. students in two consecutive years.

The conditions are being analyzed for achieving sustainable market presence of production facilities using charts that reflect the successive changes depending on their production program. Variations have been established in which there are prerequisites for ensuring the sustainability of market presence.

There are many variants of solar collectors on the market with their advantages and disadvantages. The innovative solution of solar thermal collector has been done to increase efficiency and improve design. The new constructive solution presents good combination of an attractive design and appropriate constructive materials with special geometric shapes. Hydraulic and thermotechnical tests of this collector showed high hydraulic and structural stability. The main disadvantage is selective electrochemical coat and further development of the solar collector will be in order to improve observed disadvantages.

In the report the methods for controlling and managing the processes in agriculture are justified and systematized and a methodology for applying the statistical methods for analysis, control and management of the quality of the agricultural processes has been developed. Finally, the factors influencing the quality of technological processes in agriculture are also labeled.

Irrigated agriculture plays an important role in agricultural production in Kazakhstan. In case of optimal use of land and water resources irrigated agriculture could become a significant driving force of agricultural production. Strategically important crop products such as cotton, rice, sugar beet, tobacco, vines, melons are grown only on irrigated lands of Kazakhstan.

We offer decentralized unpowered water lifting, using devices that are installed below a water source, such as a spring. The most promising of the water lifting devices of impulse type is a hydraulic ram. If the hydraulic ram is equipped with a suction tube, it is possible to increase the height difference between the source and the lowest point to the most possible value. If the hydraulic ram is equipped with a torque converter it allows: 1) to adapt optimal operating mode of a hydraulic ram to particular geodesic conditions; 2) to create in advance large-scale hydraulic rams and torque converters and to unitize them for each urgent order 3) in the second circuit, i.e. in the torque converter, any medium may be used as the working fluid: water, oil, coolant, air and so on., that helps produce energy and then transform it into useful function at maximum efficiency (≈ 90%) due to the minimal number of the energy conversion forms.

Sugar Beet Harvesters belong to self-propelled agricultural machinery for trimming, lifting, cleaning and collecting sugar beets. Like most harvesting machines such vehicles are equipped with hydrostatic traction drives to ensure a continuous variable speed adjustment for the harvesting process. These drives are state of the art but rather moderate in efficiency. For further enhancement of effi- ciency the hydrostatic system was replaced by a diesel-electric traction drive. The two different systems were tested and compared in simula- tion and field. As a result, improved driving performance at reduced fuel consumption could be achieved.

The theoretical fundamentals of the new technology water heating by thermal jet module were substantiated. Formulas for determining the energy parameters of the thermal module by heating the water were given. The main advantages and disadvantages of previously developed heat generators were shown.

A design for a new thermal jet module with improved energy parameters and advanced capabilities of its use was created on the basis of theoretical research.

A new developed structural and technological scheme of thermal jet module was given, which in comparison with analogues has advantages in improving energy performance .

The proposed construction of a thermal jet unit has a scientific and technical novelty , enhances energy performance increasing the efficiency of the use of the cumulative effect of water heating by friction counter opposing layers of water of rotational and translational motion , friction forces of moving jets of water and air at different speeds , and heat transfer when exposed air to water with generated vacuum and cavitation.