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1
Content available Destruction of the Structure of Boiling Emulsions
EN
In this paper we consider the processes of dynamic interaction between the boiling particles of the dispersed phase of the emulsion leading to the large droplet breakup. It is indicated the differences in the consideration of forces that determine the crushing of non-boiling and boiling drops. It is determined the possibility of using the model to define the processes of displacement, deformation or fragmentation of the inclusion of the dispersed phase under the influence of a set of neighboring particles. The proposed method allows us to determine the main energy parameters of the homogenization process by boiling the emulsion.
PL
W tym artykule rozważamy procesy dynamicznej interakcji między wrzącymi cząsteczkami zdyspergowanej fazy emulsji, prowadzące do rozpadu dużych kropel. Wskazano na różnice w uwzględnianiu sił, które determinują kruszenie kropli niewrzących i wrzących. Określono możliwość wykorzystania modelu do zdefiniowania procesów przemieszczenia, deformacji lub fragmentacji włączenia fazy rozproszonej pod wpływem zestawu sąsiednich cząstek. Proponowana metoda pozwala określić główne parametry energetyczne procesu homogenizacji podczas ogrzewania i wrzenia emulsji.
EN
Mining and metallurgical enterprises generate a significant amount of secondary raw material resources having small-fractions (below 3 mm). A significant volume of these materials can be returned into the production process by the use of the briquetting method. The quality of briquettes, in particular, their strength, is significantly affected by a phenomenon called elastic after-effect. For a theoretical study of the elastic after-effect influence on the quality of the briquettes, taking into account the pressing tool configuration, experimental data are obtained for three materials (peat, kaolin and manganese concentrate). Results are in creating the analytical relations (regression models) having enough high accuracy to describe the dependence of compaction coefficient, elastic after-effect, density and elastic heave (decompaction) on an external pressure in the compaction machine.
3
Content available remote Research of environmental and technological problems of cavitation
EN
The comparative analysis of systems of conversion of electric energy into mechanical and mechanical into thermal with realization of effect of cavitation in a stream of the liquid transported in a closed circuit is carried out. The optimal dimensions and relief of working surfaces of swirlers in tubular and rotary cavitators are determined. The regularities of the change of the coolant temperature depending on its nature, the intensity of cavitation, which is determined by the rotational-translational and rotational motion in cavitators of two types - tubular and rotary.
EN
Based on the mechanical properties of stretch fabrics and Laplace’s law, the mathematical models have been developed enabling one to determine the values of the relationship between the fabric strain and the circumferential stress depending on pressure and diameter of the body. The results obtained refer to the values of the parameters assessed for the initial phase of their exploitation, which allow us to preliminarily predict the values of these parameters.
EN
Ballast layer has weighty share in the lifecycle costs of railway track. The strict standards and maintenance rules of ballast grading significantly contribute to the ballast costs. One ways to the costs reduction is differential demands to ballast grading for the secondary and low loaded railway lines. Additional one is the different ballast grading over the ballast height. This study presents a full scale laboratory investigation of technical efficiency of such railway ballast under the long-term cyclic loading in comparison with the standard ballast layer. The double layer is presented with standard grading ballast upper layer and bottom sub ballast layer consists of ballast mixture. Pressure distribution under the ballast layer and permanent settlements of the layers are measured during the loading cycles. The reference measurements with standard grading ballast material are carried out. The study shows that initial settlement accumulation of the double layer railway ballast are lower to that of the standard ballast layer. However, the settlements accumulation intensity of the ballast is higher. The analysis of the pressure distribution measurements under the ballast layer and the settlements inside the ballast layer explain the causes of the different settlement accumulation.
EN
The mathematical model for calculating the response time of the compression ratio of the mechanism for compression ratio changing (MCRC) is presented in this article. This revealed the influence of various engine factors with the connecting rod and crank mechanism (CRCM) on the operation of the MCRC (for example, the rate of the compression ratio change). The results of the study of the operation of the MCRC indicate a strong influence of the values  (relative area of flow passage of channels) and р (pressure) on the response time τ in the field of their small values. This indicates that with insignificant changes of the area of flow passage of channel of the hydraulic lock and the minute oil pressure in the cavities, a significant response rate of the MCRC is ensured. The results demonstrate the possibility of speedy compression ratio change in the engine with the MCRC. Calculation studies showed that the mechanism full operation occurs quickly (0.02 s per unit εx), which indicates the expediency of using such a high-pressure pump in a four-stroke gasoline engine with CRCM. The mechanism movable body complete movement (S = 4 mm) at the oil temperature in the hydraulic system of 45°C and pressure on the body of p = 60 bar are stated to occur for 0.2 s.
EN
In recent years, the development of IT systems for fleet monitoring was observed. Tire pressure monitoring systems are constantly improved. Decreased values in tire pressure can cause deformation of tires. Monitoring of tire pressure is an important function in oversized transport trucks. Tire pressure and rolling resistant influence fuel consumption. The purpose of this paper was to determine the impact of tire pressure on fuel consumption in a fleet of trucks with tire pressure monitoring system installed and to determine the impact of other factors that may affect fuel consumption, such as the vehicle weight, brake usage and cruise control usage. The results of the research were developed using a multiple regression model describing the above dependence.
8
Content available remote Micro-bending sensor made from polydimethylsiloxane
EN
The article describes the process of manufacturing micro-bending sensors from polydimethylsiloxane and the checking of their function on the basis of damping behaviour. We tested three manufactured alternatives and from the results we determined coefficients for the calculation of the mass of weight on the assumption that the level of damping is known. We also tested the micro-bending sensors in practice as a walking detector, we can imagine similar uses for the sensor because it is compact, reliable, simple to produce, resistant to unfavorable conditions and cheap.
PL
W artykule opisano konstrukcję czujnika ugięcia wykonanego z polydimethylsiloxanu. Zbadano trzy alternatywne konstrukcje i określono masę obliczeniowoą przy założeniu że poziom tłumienia jest znany. Zbadano też praktyczne zastosowanie czujnika jako detektora kroków.
EN
The article presents an assessment of the susceptibility of friction linings from two selected manufacturers. These tests are extremely important when assessing the safety of existing and newly designed shaft lifts and ski cableways. The research was carried out on measuring equipment at the Department of Mining Mechanization and Robotization of the Silesian University of Technology, where this type of research has been conducted for years. A measuring amplifier, road transducers, force transducers and a hydraulic testing machine were used for the tests, thanks to which the pressure was applied to the rope on which the friction lining was applied. The measurements were recorded on a computer, which was a recording and measuring station, after which they were processed, saved in tables and presented to the reader in the form of graphs. The main purpose of these tests was to obtain results giving information about the rope displacement at a specific pressure to the groove of the friction lining. It is also worth mentioning that the factor that has a significant impact on the achieved values of displacements is the time of the test. It is related to the properties of the material of which the friction linings are made that are used as a running track for the ropes.
EN
The thermoelastic behavior of a bi-material with a gas-filled interface crack is investigated. The bi-material is subjected to a uniform tensile load and a uniform heat flow. The gas exerts pressure on the crack surfaces and offers thermal resistance proportional to the crack opening. The gas state is assumed to be described by the ideal gas law. The effects of gas mass, gas thermal conductivity and heat flux on the crack opening, interface temperature jump, gas pressure and stress intensity factors are analyzed. It is revealed that a bi-material with a heat-conducting crack exhibits the heat flow directional effect.
EN
Excessive soil compaction caused by agricultural tractors during plant production processes results in a considerable risk of reduced crop yields, increased erosion processes, greater input of energy in tillage and increased CO2 emission to the atmosphere. As a consequence we observe a threat of degradation in Luvisols found over a considerable area in the Polish Plain and the North European Plain. In-situ studies made it possible to identify and quantify selected factors determining soil density in loamy sand at a depth of max. 0.4 m in wheel tracks of tractors weighing from 19 to 72 kN with single standard wheels and with dual wheels. Analyses were conducted during the first passage over soil loosened during ploughing. It was generally shown that at a lower initial soil density in the topsoil tractors with both driving systems cause greater density increments and lower soil density than in the hardpan. Tractors with dual wheels exert much lesser pressure and cause soil density by approx. 0.1 g·cm-3 lower in the topsoil and by approx. 0.06 g·cm-3 in the hardpan than it is the case for tractors with single wheels. Tractors varying in their weight cause similar soil densities in the topsoil, while in the hardpan heavier tractors cause greater soil densities than light tractors. Generally, tractors with single wheels compress the soil in the topsoil layer to 45 up to 65% of compressibility, while tractors with dual wheels do it to approx. 26 up to 49% of compressibility, respectively.
PL
Nadmierne zagęszczanie gleb ciągnikami rolniczymi w produkcji roślinnej powoduje znaczne ryzyko obniżenia plonowania roślin uprawnych, wzmożenia procesów erozyjnych, wzrostu energii na uprawę i zwiększenia emisji CO2 do atmosfery. W konsekwencji występuje zagrożenie degradacją gleb Luvisol występujących na znacznym obszarze Niżu Środkowopolskiego i Niżu Środkowoeuropejskiego. W badaniach polowych dokonano identyfikacji i kwantyfikacji wybranych czynników determinujących gęstość gleby - piasek gliniasty - na głębokości do 0,4 m w koleinach ciągników o ciężarach od 19 do 72 kN z pojedynczymi kołami standardowymi i z kołami dodatkowymi. Badania wykonano podczas pierwszego przejazdu na glebie spulchnionej podczas orki. Wykazano ogólnie, że przy niższej początkowej gęstości gleby w warstwie ornej ciągniki z obydwoma systemami jezdnymi powodują wyższe przyrosty gęstości gleby i niższe gęstości gleby niż w podeszwie płużnej. Ciągniki z kołami dodatkowymi wywierają znacznie mniejsze naciski i powodują mniejsze gęstości gleby średnio o ok. 0,1 g·cm-3 w warstwie ornej i o ok. 0,06 g·cm-3 w podeszwie płużnej niż ciągniki z kołami pojedynczymi. Ciągniki o różnych ciężarach powodują podobne gęstości gleby w warstwie ornej, a w podeszwie płużnej ciągniki cięższe powodują większe gęstości gleby niż ciągniki lekkie. Ogólnie ciągniki z kołami pojedynczymi zgęszczają glebę w warstwie ornej od 45 do 65% potencjału zgęszczenia, a ciągniki z kołami dodatkowymi w ok. 26 do 49% tego potencjału.
EN
In the present work, a solution to the problem of viscous flow in a rectangular region with two moving parallel walls is obtained by using a hybrid finite volume scheme. The discretized governing equations are solved iteratively, and thereby the flow variables are computed numerically. The results for velocity and pressure in horizontal and vertical directions through the centre of a rectangular region are elucidated. The nature of velocity profiles and pressure for different Reynolds numbers in the horizontal and vertical directions through the geometric centre was analyzed with the help of pictorial representations. The present results are compared with the available benchmark results and we have found that they are not in disagreement.
EN
In the present paper, we have studied the temperature and pressure dependent creep stress analysis of spherical shell. The review is critical to enhance the warm resistance of spherical shells in high-temperature conditions. The effect of different parameters was studied and it was noticed that the parameter n has a significant influence on the creep stresses and strain rates. Creep stresses and strain rates are ascertained on the premise of summed up strain measures and Seth’s transition hypothesis. This investigation is completed to demonstrate the impacts of temperature on the creep stresses and strain rates in the spherical shell. The resulting quantities are computed numerically and depicted graphically. It has been watched that the spherical shell made of an incompressible material is on more secure side of configuration when contrasted with the shell made of a compressible material.
EN
To transport of the air in the pipeline, an analytical model is developed that takes into account the gas velocity, its kinematic and dynamic characteristics - density, viscosity depending on the pressure in a given space of the pipeline. The analytical model makes it possible to calculate the coefficient of friction of gas transportation in the pipeline at intervals of the absolute pressure from 220 to 2 kPa and M < 1 Mach numbers, depending on the diameter and length of the pipeline and physical and technological characteristics of the gas. The K1* aspect ratio is proposed, which characterizes in time the ratio of the dynamic force of movement of gas to the static pressure related to the diameter of the pipeline. The coefficient of air friction was modeled according to the vacuum pressure as a parameter of density and air flow. Air flow was taken from 1.917·10-3 m 3/s to 44.5·10-3 m 3/s respectively, diameters from 0.030 to 0.070 m and Mach number was M = 0.005-0.13. At the vacuum and excess pressures with increasing of Reynolds number and decreasing of Mach number the gas friction coefficient increased linearly. According to the simulation results as the pressure loss and the diameter of the pipeline are increased the friction coefficient increased as well. Analogically, at the vacuum metric pressure when the pressure loss and the diameter of the pipeline are increased the friction coefficient increased. At the pipeline internal diameters of 22, 30, 36 mm accordingly for pressure losses from 2 to 14 kPa the coefficient of air friction varies from 0.006 to 54.527 respectively.
EN
The article presents the results of tests carried out on a single-cylinder of spark-ignition engine. The charge exchange process in the combustion chamber is very important to determine the possibility of improving the overall efficiency of the engine. Describes of impact modifications engine on open indicator diagrams. Open indicator diagrams show that the higher compression ratio is assumed, the higher the pressure in the system is. First parts of the research describes analysis of charge exchange on not working engine. Results of research presents different open indicators diagrams. Then the pressure results were obtained on the working engine. The possibilities of improving the overall efficiency of the engine by reducing the pumping loss, associated with the replacement of the air fuel mixture, were presented. The article describes the modification of a spark-ignition engine that affects the pressure change in the combustion chamber. The use of innovative methods of regulating the compression pressure gives a lot of positive effects.
EN
Power cartridges are gas generators utilised to drive a liquid projectile for disruption of suspect improvised explosive devices (IED’s). The purpose of a water-jet disruptor is to destroy the suspected IED. A novel method was devised for pressure measurement at the exit of the cartridge for launching liquid projectile. An experimental test set-up was designed and fabricated for measurement of projectile velocity and the propellant gas pressure in a velocity test rig (VTR). In these experiments, double base propellants having different physical and chemical properties were utilised to drive the solid projectile. This projectile was made of nylon material. This projectile velocity measurement is an important parameter in the armament field. An experimental study is the unique design feature. It is responsible for the measurement of pressure at the exit of the cartridge and the projectile velocity at the muzzle end of the barrel. The projectile velocity was measured using high speed photography. The pressure was measured using a pressure sensor. The maximum projectile velocities for spherical ball powder and NGB 051 propellants have been experimentally measured as 384.23 m/s and 418.32 m/s, respectively. Experimentally the maximum pressures for spherical ball powder and NGB 051 propellants have been evaluated as 50.12 MPa and 63 MPa respectively from data gathered by the acquisition system. The standard deviation between the experimental and theoretical values for the projectile velocity varied from 12.57 to 13.88 for spherical ball powder whereas it was 5.33 to 7.09 for NGB 051 propellant. The percentage error between the experimental and the theoretical values of the projectile velocity was less than 10 for both propellants.
EN
Gas atmosphere at the sand mould/cast alloy interface determines the quality of the casting obtained. Therefore the aim of this study was to measure and evaluate the gas forming tendency of selected moulding sands with alkyd resins. During direct and indirect gas measurements, the kinetics of gas evolution was recorded as a function of the temperature of the sand mixture undergoing the process of thermal destruction. The content of hydrogen and oxygen was continuously monitored to establish the type of the atmosphere created by the evolved gases (oxidizing/reducing). The existing research methodology [1, 7, 8] has been extended to include pressure-assisted technique of indirect measurement of the gas evolution rate. For this part of the studies, a new concept of the measurement was designed and tested. This article presents the results of measurements and compares gas emissions from two sand mixtures containing alkyd resins known under the trade name SL and SL2002, in which the polymerization process is initiated with isocyanate. Studies of the gas forming tendency were carried out by three methods on three test stands to record the gas evolution kinetics and evaluate the risk of gas formation in a moulding or core sand. Proprietary methods for indirect evaluation of the gas forming tendency have demonstrated a number of beneficial aspects, mainly due to the ability to record the quantity and composition of the evolved gases in real time and under stable and reproducible measurement conditions. Direct measurement of gas evolution rate from the tested sands during cast iron pouring process enables a comparison of the results with the results obtained by indirect methods.
EN
In this Paper, a parametric study on pipes buried in soil was performed illustrating the results of blast loading. Effects of various parameters such as the physical properties of water, oil, gas, air, soil, pipes, and TNT have been investigated. The arbitrary Lagrangian-Eulerian (ALE) method was employed using LS-DYNA software. The maximum pressure in a buried pipe explosive was observed at an angle of about 0° to 45° and the minimum pressure occurred at an angle of about 45° to 90°. Therefore, all figures in this study illustrate that fluid pressure levels in buried pipes can help in their stabilization. In generally, by increasing the 1.23 times of liquid density under the explosion, the pressure levels in the soil decreased by 1.3 percent. The gas pressure has been increasing more than oil and water pipes 39.73 and 40.52 percent, respectively.
EN
The main purpose of this research was to analyse the distribution of plantar pressures and foot characteristics during walking between weeks 27 and 36 of pregnancy. The secondary purpose was to test the effect of the customized orthopaedic shoes that were worn by the experimental group. Methods: Pregnant women (n = 73) were divided into 2 groups, control group (n = 38) and experimental group (n = 35) which completed 5 gait trials on a walkway (1.55m) at a self-selected velocity of gait, where force, pressure and remaining foot characteristics were sampled and displayed by Novel database pro m (version 25.3.24). Results: Analysis of foot characteristics did not reveal important changes. Analysis of the distribution of plantar pressures revealed few changes in the pre- and post-measurement of the experimental and control groups between weeks 27 and 36 of pregnancy. In the last measurement, there is a significant increase of peak pressure only in the midfoot area of the left foot (151.1 ± 41.2 kPa) and in the hindfoot area of the right foot (346.3 ± 104.1) of the experimental group. The control group exhibits similar pressure development for both of foot. Conclusions: Monitored parameters demonstrated in certain areas notably development of force and contact area. Results of foot characteristics did not reveal a significant changes. As both groups registered similar values in certain areas in a comparison of pre/post measurement characteristics, the influence of specific orthopaedic shoes cannot be conclusively demonstrated in the experimental group.
EN
This current work investigates the effect of duct and number of blades on the hydrodynamic performance of the horizontal axis tidal stream turbine (HATST). The numerical method based on Reynolds averaged Navier-Stokes (RANS) equations is employed to compare the hydrodynamic performance for various cases of this device. For validation of the numerical results, a 3-blade HATST without-duct has been compared against experimental data. The analysis and comparison of the simulation results show that using duct for HATST has increased the power coefficient, the torque coefficient, the trust coefficient, and the force on the blade. In addition, the simulation results of the cases with a greater number of blades shows that the trust coefficient increased and the force on the blade decreased. Therefore, it is recommended to use ducted HATST with a great number of blades to extract more energy from the tidal stream.
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