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The Effect of General Low Frequency Vibration on EnergyBalance of a Human Being

100%
Damijan Z., Uhryński A.
Acta Physica Polonica A
|
2013
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vol. 123
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issue 6
970-973
EN
The work presents the research and analysis concerning general low frequency vibration and its effect on energy balance of a human organism (a comparison with a control group). The research was conducted in two phases: a group exposed to vibration and a control group. An exposed group (28 participants) took part in 19 training sessions, each lasting 20 min, of low frequency vibration (around 3.2 Hz in standing position) applied to each participant at fixed time of the day. Before and after the session, the thermographic images were taken and deep temperature was taken too. The control group (33 participants) also took part in 19 everyday 20-min sessions with no vibrations and only measurements conducted. The results were analysed concerning statistics using Statistica. For the sake of the analysis the significance level was p = 0.05, the parametric T - test, and the non-parametric Kołmogorow-Smirnow tests were used for two groups of independent variables. Having conducted the research and analysis, one can state that 20-min exposure to low frequency vibration results in significant positive changes in chosen parameters.
2
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Study of the Structure and Thermal Properties of Intermetallics from Fe-Al System

80%
Śmiglewicz A., Rodak K., Tomaszewska A.
Acta Physica Polonica A
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2016
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vol. 130
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issue 4
1004-1006
EN
Selected alloys from the Fe-Al system are included into a group of materials on a matrix of intermetallic phases, and characteristic properties result from it and they constitute a resultant between properties of superalloys and ceramic materials. These materials are characterized, inter alia, by capacity for operating at elevated temperatures, as well as good strength related properties and resistance to oxidation and corrosion at an increased temperature. In addition, a low cost of alloy components and low density caused by aluminium content are their advantages. The basic reasons limiting application of alloys from Fe-Al system as construction materials are current: their low plasticity at room temperature, propensity for brittle cracking, low resistance at elevated temperature, and insufficient creep resistance. This unfavorable characteristics may be improved by adding to alloys such elements as molybdenum, zirconium, carbon, and boron, reducing the size of grains, increasing their purity, stabilizing the solid solution, and causing changes in phase transition temperatures. These alloys may be successfully manufactured by classic melting accompanied with refinement remelting, and ingot casting. In spite of additions and microadditions, grain refining of the initial structure of ingots manufactured in that way is rarely achieved, mainly because of low castability and high casting contraction. In this work we presented the results of structure analysis and investigations of the dilatometric study alloys on the base Fe-Al system. The alloys were obtained by classic casting technique. The studies were carried out on samples after casting and annealing. The phase transformation and thermal expansion investigations of the alloys from Fe-Al system with concentration of Fe-58Al were presented. The linear thermal expansion α was calculated by standard method. The α coefficient was noticed as a temperature function.
3
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Design of a Laboratory Unit Air-Conditioning System with Matlab/Simulink Software

80%
Koçyığıt N., Şahın M.
Acta Physica Polonica A
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2017
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vol. 132
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issue 3
839-842
EN
In this study, design of an electronic air-conditioning system was carried out using Matlab/Simulink software. The air-conditioning system was designed as a laboratory experimental setup. The aim of this study was to revise and to reuse an outdated air-conditioning laboratory unit, by using improved methods. General equations were defined separately for each part and cell of this air conditioning system. Using these equations Matlab/Simulink models for every component were created. The Matlab/Simulink models were combined and verified with theoretical results. The simulation results show that theoretical results are compatible with the simulation results. These results were tested for input and output air enthalpy values and for humidity values. In addition, air mass flow rates for the number of different fan speeds were compared. The coherent simulation results showed that the general model of the air conditioning system, designed in Matlab/Simulink, behaves correctly. This model will be used in the future studies for comparison of real system results with simulation results.
4
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Characterization of Temperature Field Distribution in Large-Size Paratellurite Crystals Applied in Acousto-Optic Devices

80%
Tretiakov S., Grechishkin R., Kolesnikov A., Kaplunov I., Yushkov K., Molchanov V., Linde B.
Acta Physica Polonica A
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2015
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vol. 127
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issue 1
72-74
EN
Temporal and spatial distribution of temperature field was studied in operating acousto-optic devices on base of large-size paratellurite crystals. The study was carried out in real time by means of thermal imaging technique. Dynamics of heat release in a hot deflector and a hot tunable filter was examined at different frequencies and driving electric power levels applied to piezoelectric transducers. The study was also based on measurements of standing wave ratio and analysis of the Smith charts.
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