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

The main goal of my work was to design a dry well wastewater pumping station. The products of the pumping station market, the related literature, and the standards were analysed. The collected information was summarized in the catalogue of the requirements. I created the parametric 3D model of the total pumping station. Some of the dimensions are linked from an MS Excel file, and others change like a function. Thus, we can get the pumping station model with the required parameters without changing the model directly. The system’s pressure loss was calculated, which is necessary to know the working point of the pumping station. The mass of the concrete we need against the uplift was specified. The dry well makes the sewage system more stable; it has a lower environmental effect and makes the maintenance safer.

Mathematical methods of quantum mechanics are needed to describe the contact phenomena of the boundary casting/mold. Apart from the macro-level, the contact phenomena are part of the technological processes first order phase transition and second order phase transition. Need for professional software for mathematical simulation at macro- and micro-level in foundry. Education in basic mathematics and mathematical physics is also required for engineers. The branch machine-building infrastructure must develop a mechanism for inclusion in the computing infrastructure of the micro-foundries.

The article presents the results of modeling quasi-stationary ultralow power electric fields (the order of tens of nanowatts) and establishes ranges of rational values of parameters (average density of electric voltage, specific potential) of these fields. As a result of mathematical modeling (based on a system of Gaussian equations) and subsequent numerical experiment, it is shown that an instantaneous increase in the average electric density of a quasi-static electric field in 2 times in one part of the field leads to an increase in charge redistribution time from 34 ns (at an initial density of electric tension of 17 nN/Ku.μm 3) to 189 ns (at a density of electric tension of 145 nN/Ku.μm3). This redistribution allows us to determine the range of rational values of the specific potential, which is 1.1… 9 nV/μm 2. In this case, the maximum specific power that can occur in such a field is 0.5… 0.77 nW/μm 2.

The transport sector is a major consumer of diesel fuel, which ranks it among the main greenhouse gas (GHG) emissions generators. They can be reduced by gradually introducing biofuels into transport fuels and their share is expected to increase over the years. However, full sustainability can only be achieved by simultaneously consideration of all stages of the product life cycle with a tendency to close it, by utilization of solid waste by-products to improve the energy efficiency of considered biofuel production.
This study proposes an approach for optimal design of an Integrated Biodiesel/Diesel Supply Chain (IBDSC) based on 1st generation feedstock, taking into account the impact of the used feedstock for its energy efficiency improvement. It based on mathematical models of the environmental and economic impact of the considered IBDSC. The latter are included in an optimization problem for determination of optimal number, size and location of bio refineries and solid waste facilities; areas and quantities of raw materials needed for the production of biodiesel and mode of transport. Two optimization criteria are defined: environmental – minimum generated GHG emissions from IBDSC operation and economic – the total annual costs optimization criteria. The problem is solved if either at one of the two criteria, or at an integrated environmental and economic criterion. The approach involves an additional analysis of different feedstock as well as useful byproducts. Based on this analysis, the sunflower has been selected as the most appropriate feedstock which can be used as a generator of a useful by-product – sunflower husks. The obtained optimal amount of sunflower husks generated in the production of tons of biodiesel is 0.431(/.). They are used to produce the required amount of heat in biorefineries, where there are plants for burning flakes and is 0.215(/.). The remaining amount of sunflower husks is used for the production of pellets. When using an integrated environmental-economic optimization criterion, the following results are obtained – 33.4% of sunflower husks are used for the production of pellets, and 66.6% for the production of heat in biorefineries. This would have a positive impact on the formation of the final price of biodiesel.

Mean value models are essential for developing control engineering methods, e.g., speed control concepts, failure monitoring features. This work briefly summarizes the main parts of such a second-order mean value model, suitable for control engineering purposes. The nonlinear model is linearized around one operating point, and a linear state controller is designed, both for single-input and multipleinput, without and with an integral component to eliminate steady-state deviations. Limitations of the proposed linear control concepts, potential advantages of nonlinear flatness-based control concepts, and possible extensions of the model for fuel identification are discussed in the outlook.

The article presents a description of the mathematical model of the curvilinear movement of a tracked vehicle with a complex steering mechanism, which contains a control hydrostatic branch and an additional hydrodynamic branch for unloading the first. The adequacy of the presented mathematical model was verified by calculating the characteristics of the turn in place of the Leop ard-2 tank. The resulting tool can become the basis for parametric optimization of similar steering mechanisms for tracked vehicles.

In the design phase of transport systems, a significant step is also the traffic light regulation. In world practice, to evaluate the efficiency of the proposed theoretical methods, experiments on test transport systems and on real systems are carried out. The obtained results allow for the confrontation between different methods and the definition of those to be used in professional practice. For the semaphorical adjustment project, the algorithms proposed by the world literature were used in test networks with a non-large number of defining variables, so with as much semaphorized crossings in the project. This small number of variables makes it possible to find the optimal solution of the problem and evaluate how much the proposed approximation approaches this solution. While for the common topology project and traffic light regulation, algorithms were experimented in real transport systems. For this we chose two areas with about 60,000 inhabitants, respectively in Tirana and Durres. Since many of the half hypotheses used in the phase when acting on topology variables depend on one or several parameters, different values were used in order to reach their calibration . Next, the algorithms, with the calibrated parameters, will be used in another city. But this will be the subject of a future study.

Due to various interferences arising from the tropospheric propagation of radio waves over big water basins, it is necessary to study in detail the mechanisms of propagation and to improve the existing models for determining propagation factor or path loss profiles at different frequencies, especially in UHF bands, caused by the growing interest of mobile communications and especially 5G technologies. To get enough information about radio wave propagation over the Black sea area, the state of atmosphere above points of interest is studied in detail and the results are compared with real measured radio signals distributed between those points. The results are compared with basic theoretical computed models. The results showed more than 10 dB and from 6 to10 dB difference respectively for VHF and UHF between measurement and computed with Three way path loss model EMF levels for the favorable cases which might be due to additional ray in the receiver. A clear relationship between received EMF levels and wind speed but in combination with different abnormal tropospheric environments and relationship between absolute value of modified refractivity and the levels of received signals for the surveyed regions

The paper theoretically substantiates and practically implements mathematical methods of modeling production systems, proves the adequacy of mathematical models and optimization methods, as well as selected rational optimization methods and created software that implements the selected methods in practice. The analysis of methods of modeling and optimization of production technological systems is performed, the most effective methods of solving these problems for discrete production are selected. The main provisions of infinite-valued logic and ordinal determinants, on which the structural-logical approach to the study of complex systems, which include production systems in instrument making, are considered.

The creation and calculation of computer models of various products under load with the properties of UFG materials in the normal and irradiated state was performed. To model the UFG properties of non-irradiated AISI-321 steel, hardening curves were constructed based on the Hall-Petch equation for the base state of the material at a grain size of 1500 nm and for two UFG states (with grain sizes of 700 and 200 nm). To simulate the properties of irradiated AISI-321 steel, plastometric tests were performed using uniaxial compression of cylindrical samples at constant values of the strain rate of 1 s-1 and the temperature of 20°C on the “Gleeble 3800” plastometric unit. Fast neutron fluence with the following values was selected as a variable parameter: 0.5∙1018 n/cm2, 1∙1018 n/cm2, 0.5∙1019 n/cm2, 1∙1019 n/cm2. The maximum operating pressure of 340 MPa was used as a static load. The simulation results showed that for both parts, the use of the material in the UFG state is the most appropriate solution.

Thermal comfort and indoor air quality highly depend on proper design of Heating, Ventilation and Air Conditioned (HVAC) system. These system require large amounts of energy. Efficient use of energy leads to new concept design of HVAC systems. In this article, energy consumption in office building is analysed using Hourly Analysis Program (HAP) software. The aim of this research work is focused in estimation of office building energy consumption considering three different HVAC systems, respectively. Therefore, Variable Refrigerant Flow (VRF) system, HVAC 2-pipe and HVAC 4-pipe system were analysed with respect to energy consumption. A typical office building placed in Tirana, of 5000 m2 of total area is used for this study.

It is created computer model of wire extrusion process with Matlab. The model is verified by comparing the simulated results with experimental.