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

In this paper we will study an important part of the speech signal processing, the reconstruction of the signal. We will use the Newton interpolation method with a deterministic model and warped frequencies in order, maybe, to get a better reconstruction process of the signal. To determine the efficiency of the method we will use two criteria like: accuracy of reconstruction, noise stability. Then we will test this algorithm using the criteria that we proposed above versus the classic Yen’s algorithm. At the end of our experiment we will see that in noise stability our algorithm performs better but not in the reconstruction accuracy. In overall Yen’s algorithm performs slightly better.

One of the most critical consumable expenses in the production of wet wipes is the anvil and knife set used in the cutting unit. Blades that lose their cutting ability over time and become unable to perform their task pose a significant challenge. As wet wipes are essential products for maintaining hygiene and directly affect human health, even the slightest disruptions in production conditions are unacceptable. To ensure the quality and consistency of wet wipe production, it is vital to analyze the factors affecting the strenght of cutting blades and implement the necessary precautions. One of the key factors influencing the wear of cutting tools is the mechanical strength of the tool’s carrying unit. This paper explores the importance of cutting tools in wet wipe production, the role of mechanical strength in maintaining their effectiveness and application of mathematical modeling to design.

This paper presents results of two different isentropic analysis types: conventional isentropic analysis which considers the whole steam turbine cylinder and segmental isentropic analysis which considers all cylinder parts (segments). In conventional isentropic analysis is obtained that isentropic efficiency of the analyzed turbine is 73.39%, what is in a range of expected isentropic efficiencies for such steam turbines (in the mechanical power range around 60 MW). Segmental isentropic analysis shows that the last two segments (fifth and sixth segment) of the analyzed turbine did not show proper operation (especially the fifth turbine segment which isentropic efficiency is unacceptably low and equal to 26.73% only). Such isentropic efficiency results, related to the fifth and sixth turbine segment, indicate highly problematic operation, or the most likely malfunction of at least some turbine stages in these segments. For the analyzed steam turbine can be recommended that it should be stopped as soon as possible and that turbine stages mounted in the last two segments should be checked, repaired or replaced.

By using the application package ANSYS Fluent, the numerical simulation of heat and mass transfer processes in the channels of shell-and-tube heat exchanger with compact placement of tube bundles has been carried out. The fields of velocities, temperatures and pressures in the heat exchanger channel were obtained and the conditions of hydrodynamic flow in the channels and the processes of heat transfer in these channels were analyzed. A new construction of shell-and-tube heat exchanger with compact arrangement of tubes in tube bundles is proposed and developed.

In the presented work a new identification method of difficult measured internal quantities of IM, such as components of magnetic flux vector and electromagnetic torque, is proposed. Commonly measurable quantities of IM like stator currents, stator voltage frequency and mechanical angular speed are used for identification to determine a feedback effect of the rotor flux vector on vector of stator currents of IM. Stability of the identification structure is guaranteed by position of roots of characteristic equation of its linear transfer function. Results obtained from simulation in MATLAB measurements confirm quality, effectivity, feasibility, and robustness of the proposed identification method.

It is often assumed that if practical difficulties are neglected, active suspension systems could produce in principle arbitrary ideal behavior. This paper presents the factorization approach that is taken to derive limitations of achievable frequency responses to active vehicle suspension systems in terms of invariant frequency points and restricted rate of decay at high frequencies. The factorization approach enables the determination of complete sets of such constraints on various transfer functions from the load and road disturbances for typical choices of measured outputs and then chooses the optimal vector of the measurements from the point of view of the widest class of the achievable frequency responses. Using a simple linear two-degree-of-freedom car suspension model, it will be shown that even using complete state feedback and in the case in which the system is controllable in the control theory sense, there are still limitations to suspension performance in the fully active state.

As plastic products shrink during cooling, so knowledge of shrinkage factor for different materials is required. The main objective of the study is to examine the influence of mold cooling process on subsequent deformation of finished part. To achieve the goal, simulations were carried out at different temperatures of the cooling agent. Statistical processing was performed and a regression model was derived describing the relationship between temperature, time and deformation during cooling.

This paper shows the determination of tightening weight travelling distance for the zipline. A rope for a zipline can be fixed at both ends, or it can be fixed at one end and tightened with a weight at the other. A both-sided anchorage is simpler to perform, but there is a problem with large changes in the rope force due to temperature differences and due to the movement of the load on it. With a rope that is fixed at one end and tightened with a weight at the other end, there are no such problems, because the force in the rope is always the same, but care must be taken to ensure sufficient travel of the tightening weight. The required travel of the weight is affected by temperature changes, ice buildup and snow, but also by the movement of passengers on the rope itself. Formulas based on which the weight movement is calculated are derived in the paper.

The dynamic stability of a cracked pipeline resting on a Winkler elastic foundation and immersed in fluid that is moving with a particular velocity is investigated. The Galerkin method is employed to approach numerically the problem. Conclusions are drawn on the influence of the rigidity of the Winkler elastic foundation on the critical flow velocity of the pipe.

In this paper is presented the method of planning and analysis of the materials handling line in one production company. The method consists of design, simulations, and analysis with the support of Arena simulation software. The design of the line is accomplished using modular modelling with interconnected modules and blocks, and simulations will be carried out to view the flow of boxes with materials and the functionality of main units and processes. The modelled line contains all the necessary units of the input processes, production and output processes, warehouses, materials handling vehicles, and the process flow of packages. Analysis will investigate key performance parameters and evaluate the functionality of the line. Production and logistics companies are implementing various software to plan and design their materials handling line, internal transports and production processes prior to the implementation and development of their plant. This enables them to plan the work, determine influential parameters and identify problems in the functionality. Results will be given in the graphical and tabular forms, which will represent the analysis of performance parameters and line efficiency.

In recent years, the problem of food safety and traceability has been one of the difficulties faced by restaurant and hotel businesses. Food spoilage can occur at any stage of the food chain; most of all food spoilage is due to improper storage conditions in refrigerators. Increasing attention to food quality and safety requires the development of sensitive and reliable analysis methods as well as innovative technologies for maintaining freshness and food quality. Freshness is a factor that has both health qualities and features that affect customer satisfaction and business profitability. Within the scope of this study, simulation studies were carried out to improve the cooling performance with mathematical modeling on a horizontal commercial refrigerator (operating temperature: -2/+8°C) prototype. Along with the original design, evaluations were made with mathematical modeling according to many different variables (temperature, airflow distribution, etc.) that affect the cooling performance, and R&D gains were achieved in developing the prototype according to the most suitable working conditions.

The study was performed to identify irrigation scheduling of some common crops such as seed-maize, tomato, carrot, rice, alfalfa, and tomato plants at arid Rosso province, Mauritania. In that purpose, crop water requirement, ETc, for those crops were calculated by Cropwat software computer program. In results, ETc values for Rice, Alfalfa, Carrot, Maize (grain), and Tomato crops were calculated as about 1378 mm, 1542 mm, 814 mm, 705 mm, and 956 mm respectively. The irrigation water requirements, I, for the examined crops were found as 1677 mm, 1535 mm, 811 mm, 699 mm, and 950 mm, respectively. In accordance with our findings, the following suggestions can be considered; crop pattern should be designated in accordance with current water resources; water delivery systems should be converted to modernized systems; deficit irrigation can be applied for some crops; farmers should be educated about correct water management, and there should be strong relationships between landowners and water managers.