Technical Transactions. Vol. 9

Technical Transactions. Vol. 9

Type: Collection of magazine numbers
Release date

Collection items (21)


Application of the multi-generating method to support the quality of smart designs of experiment

Skowronek, Andrzej
Article
2017
The article presents a method used in the process of generating smart designs of experiment in a dedicated computer program with the application of pseudo-random numbers, the use of which may have a considerable impact on the quality of generated designs. In order to increase the probability of generating the optimal design for the defined parameters of generating, a special method was applied, in which several designs were generated and the best of them selected, based on the equipartitional analysis parameters. The results confirm a significant positive influence of the analyzed method on the smart design’s quality.

Application of porous media flow model for the regenerator fluidised bed simulation

Młynarczyk, Przemysław, Cyklis, Piotr
Article
2017
Modeling a flow thorough a fluidized bed is a complicated, time-consuming and power-demanding task. However, in some cases such a flow could be simplified as a porous media flow, when we treat it as a fixed bed. This publication presents a comparison between free flow and porous media flow in order to assess the effect on the surface layer erosion.

Optimization of thread root undercut in the planetary roller screw

Lisowski, Filip
Article
2017
The paper presents the optimization problem of a thread root undercut in the roller of planetary roller screw using FEM. The depth and shape of the undercut as well as the radii of thread profiles curvature were optimized for the series of cooperating threads. The maximum HMH reduced stress in the undercut was accepted as an objective function. The limitation to the maximum contact pressure was assumed. The procedure aimed at limiting the range of variables was accepted in order to improve the efficiency of optimization method.

Influence of dual vibrations on control of percussive hand-operated power tools – experimental investigations

Książek, Marek A., Tarnowski, Janusz
Article
2017
This article presents the results of pioneer experimental research into the impact of whole body vibration (WBV) and hand arm vibration (HAV) with different amplitudes and frequencies on percussive tools which are controlled by hand. In these studies the human operator is considered as the active element of the control system. The quality of control executed by the participants of the tests was assessed by the typical parameters existing in control system engineering, such as rise time, settling time, overshoot and integral square error (ISE). The tests were performed on an especially built stand. Results are presented in the form of time histories of step reference force. Forces realized by the operator were statistically analysed and graphically presented. Local (HAV) vibration of tools and accompanying dynamic forces between the handle and the vibrating tool have a big influence on control of the tool. An increase in the frequency of the tools’ vibration increases the adjustment range. The influence of platform vibrations on the adjustment range is relatively small.

Multi-thread evolutionary computation for design optimization

Krenich, Stanislaw
Article
2017
The paper presents multi-thread calculations using parallel evolutionary algorithms (EA) for single and multicriteria design optimization. This approach was implemented to avoid a negative influence of incorrectly chosen initial and EA’s control parameters for the accuracy of generated solutions and thereby to improve the effectiveness of the EA’s use. Parallel computation for single optimization problems relies just on running n threads with different randomly chosen parameters in order to find the best final solution. For multicriteria optimization problems, each thread generates a set of Pareto optimal solutions and at the end these sets are combined together, giving a real set of Pareto optimal solutions. During the run of the algorithm, random interactions between threads were applied. The experiments were carried out using tenthread processes for different examples of single and multicriteria design optimization problems, two of which are presented in the paper.

Application of approximation technique to on-line updating of the actual cost curve in the earned value method

Kozień, Ewa
Article
2017
The Earned Value Method (EVM) is a method commonly used in the quantitative project management. The course of the actual curve is usually different from the course of the planned curve. In order to provide a reliable estimation of the time of the project implementation or its real cost, the method of on-line updating the actual cost (AC) original curve can be applied. The actual cost curve is usually of the S-curve character. The approximation method is often used in the engineering applications. In the paper, the possibility of applying the polynomial type approximation method to the on-line updating of the actual cost curve is discussed.

Homotopy perturbation method for solving fourth – order boundary value problems with additional boundary condition

Filipowska, Renata
Article
2017
This paper presents the homotopy perturbation method for solving linear and non–linear two–point boundary value problems in the form of a fourth–order differential equation and five boundary conditions. Three initial and two final conditions were taken into account. The solution of this problem is possible only when the considered equation includes an unknown parameter. The presented method has been illustrated with a numerical example.

Quality function deployment method for selected website usability analysis

Fabiś-Domagała, Joanna
Article
2017
The paper presents an analysis of the usability of a selected web site using the QFD quality method. User requirements and related technical parameters used for creating diagrams of similarities and dependencies have been identified. Diagrams showing user and technical benchmarking as well as graphs of target values evaluated for user requirements and technical parameters were created.

CFD simulation of cavitation over water turbine hydrofoils

Domagała, Mariusz, Momeni, Hassan
Article
2017
Tidal turbines are gaining more and more interest as a source of renewable energy. Energy from tidal currents may be extracted in a similar way as wind energy but tidal turbines have to meet much higher requirements. Cavitation phenomena, which are difficult to predict, have great influence on hydrodynamic efficiency. This paper presents the use of CFD simulation for prediction of cavitation during flow over typical NACA airfoils.

Continuous dependence of mild solutions, on initial nonlocal data, of the nonlocal semilinear evolution Cauchy problems

Byszewski, Ludwik
Article
2017
The aim of the paper is to prove two theorems on continuous dependence of mild solutions, on initial nonlocal data, of the nonlocal semilinear evolution Cauchy problems. For this purpose, the method of semigroups and the theory of cosine family in Banach spaces are applied. The paper is based on publications [1–6] and is a generalization of paper [3].