Technical Transactions. Iss. 7

Technical Transactions. Iss. 7

Type: Collection of magazine numbers
Release date

Collection items (16)


The microstructure and properties of titanium carbide reinforced stainless steel matrix composites prepared by powder metallurgy

Szewczyk-Nykiel, Aneta
Article
2018
TiC particle-reinforced AISI 316L stainless-steel matrix composites were prepared using conventional powder metallurgy technology. The effect of TiC content on the microstructure and properties of these composites has been investigated with a particular emphasis upon hardness, wear resistance and corrosion resistance in sea water environments. The results showed that TiC particle reinforcement improved the hardness, wear resistance and corrosion resistance of AISI 316L stainless steel. The higher TiC content in the studied composites resulted in a higher hardness of the wear surface and a lower wear rate. The best corrosion resistance in sea water was achieved for sintered AISI 316L – 5% TiC composite.

Numerical simulation of temperature distribution during the first stage of the friction stir alloying process

Nosal, Przemysław, Ganczarski, Artur
Article
2018
This work demonstrates the numerical modelling of thermal dispersion accompanying the first stage of the friction stir alloying process. It is very important to recognise the temperature field in the modified workpiece in order to identify the zones where the physical material properties are changing. The temperature gradient leads to a drop of yield strength of the material and, as a consequence, the occurrence of the possibility of plastic flow around the tool. An attempt has been made to analyse the axisymmetric thermal problem described by a Fourier equation with an internal heat source in which the heat is derived only from work of frictional forces occurring between the workpiece and the tool material. The example under consideration focuses on the production of an Al-TiC composite using FSA technology. Macrostructure images of the composite and the simulation results confirm the correctness of the applied mathematical model, where the obtained temperature field corresponds with specific FSA zones.

Two-dimensional numerical simulation of a thermoelectric cooler module

Gałek, Rafał
Article
2018
The paper presents the methodology and results of a numerical simulation of coupled thermal and electrical phenomena in a thermoelectric (TE) cooler module obtained with the MOOSE Framework released by Idaho National Laboratory. The coupled system of partial differential equations is solved for the value of electric potential and temperature fields. Equations include contributions from electric conduction, Seebeck effect, thermal conduction, Joule heating as well as Peltier and Thomson effects. The values of the cooling capacity and the voltage drop of the module are calculated and compared with the data provided by the manufacturer of the thermoelectric cooler in order to determine if the simplified assumptions adopted in the numerical model are appropriate to reliably infer about the performance of the TE module composed of over one hundred thermoelectric pairs.

A note on Browkin’s and Cao’s cancellation algorithm

Tomski, Andrzej, Zakarczemny, Maciej
Article
2018
In this paper, we follow our generalisation of the cancellation algorithm described in our previous paper [A. Tomski, M. Zakarczemny, On some cancellation algorithms, NNTDM. 23, 2017, p. 101–114]. For f being a natural-valued function defined on ℕs , s ≥1 we remove the divisors of all possible values of ƒ in the points in which the sum of coordinates is less than or equal to n. The least non-cancelled number is called the discriminator Dƒ(n). We find formulas, or at least an estimation for this discriminator, in the case of a broad class of sequences.

A prototype of a small Stirling refrigeration unit

Wrona, Jan, Prymon, Marek
Article
2018
This paper presents original mathematical models which can be used for the size optimization of particular elements in the design process of cooling appliances using the Stirling cycle. The models were used to design a prototype of the Stirling cooling device. The project employs a unique piston–cylinder kinematic pair which enables dry fiction work. Original platelet and ball ceramic regenerators were designed. The presented model assumes adiabatic transformations of the medium in the cylinders as this approach yields more realistic results in comparison to a simple isothermal Schmidt analysis. One cycle of the device (one rotation of the shaft) is divided into elementary angles Φ, where the state of the gas is considered as constant. As a result, states of the gas in individual components of the working space are determined in any given, discrete time steps of the Stirling cycle.

The application of non-standard GPR techniques for the examination of river dikes

Gołębiowski, Tomisław, Małysa, Tomasz
Article
2018
A standard measurement procedure currently applied in the ground penetrating radar (GPR) method is shortoffset reflection profiling. As this procedure delivers data that is suited only for qualitative interpretation, its application should be limited exclusively to reconnaissance surveys. There are various other techniques used in GPR surveying that may be regarded as non-standard, such as multi-offset and adaptable-polarisation surveying and tomography. Because these techniques deliver information that allows for quantitative interpretation, they could be applied for the detailed examination of geological media and investigations of various buried anthropogenic targets. This paper focuses on the application of non-standard GPR techniques for the detection of high-porosity zones in river dikes. Results from both field surveys and numerical modelling are presented.

The evaluation of control quality in automatic systems based on maximum error

Layer, Edward, Bień, Andrzej
Article
2018
The article presents an approach that uses the value of the maximum error to assess the quality of control in automatic control systems. The integral-square-error criterion is analysed together with the signals that enable its derivation. Signals with two constraints are considered.

Transport attractiveness of shopping malls

Szczuraszek, Tomasz, Karwasz, Marcin
Article
2018
The dynamic development of analytical methods used for the modelling of town travel increases the demand for various kinds of data necessary to estimate the road traffic volume on transport networks. The estimation of traffic volume generated by particular facilities located in a city is an important element of modelling. Among these facilities, large shopping malls are considered to be one of the most significant road traffic generators. The estimation of transport attractiveness of such large objects is a big challenge in modelling customers’ journey to large shopping malls. In this study, a new method is proposed for the assessment of transport attractiveness of large trade and service facilities.

Control of the vibration structure induced during works with the use of explosives

Sołtys, Anna, Pyra, Józef, Twardosz, Michał
Article
2018
This article presents the results of research on controlling the structure of vibrations induced during the firing of explosives with the use of non-electrical and electronic systems and the influence of the vibration structure during a transition from the ground to the building. The use of procedures associated with the selection of millisecond delay for firing explosive charges during blasting allows to get the excitation of favourable structure vibrations, thanks to a strong damping which is obtained at the transition from the ground to the structure. This means that optimally designed blasting works do not have to limit the mass of the explosives in the borehole as well as their number.

Comparative analysis of the coarse aggregate shapes used to manufacturing high performance self-compacting concrete

Ostrowski, Krzysztof, Oleksik, Konrad
Article
2018
The influence of the shape of coarse aggregate on the properties of fresh concrete mixes, and the strength of high-performance self-compacting concrete (HPSCC) is important issue. In this study, irregular and regular grains were separated from the basalt, porphyry and granite coarse aggregate. The shape of these grains was determining using digital image analysis and was in accordance with the European Standard [19]. The aspect ratio (AR) and roundness (R) were ascertained in order to highlight the differences in the coarse aggregate shape used the design HPSCC. The study indicates that using the same crushing system, varied parameters of the shape of coarse aggregates were obtained. It was determined that the best fitting distribution for aspect ratio and roundness at a 95% confidence level is the generalised extreme value distribution.