Wyniki wyszukiwania - Biblioteka Nauki

1

Minimalne ciśnienie statyczne w foliowych przewodach równomiernej wydajności

100%

Gładyszewska K.

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2001

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tom Z. 14

25-30

PL

W artykule przedstawiono teoretyczne metody obliczania minimalnego ciśnienia statycznego w foliowych przewodach równomiernej wydajności, potrzebnego do utrzymania odpowiedniego kształtu przewodu.

EN

The article shows the theoretical methods of calculating minimal static pressure in the regular air flow rate foil ventilation ducts which is needed to keep it in suitable form.

2

Investigation of Localised Pressure Applied to Specific Sites on the Lateral Aspect of the Foot’s Dorsum by the Upper Parts of Footwear During Sports Specific Movements

100%

Greenhalgh A. , Sinclair J. , Chockalingam N.

Human Movement

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2012

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tom 13

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nr 4

350-354

EN

Purpose. Localised peak pressure linked to overuse injuries has been documented extensively at the plantar surface during human locomotion. There is however a paucity of research investigating pressure applied to non-plantar regions of the foot during movement. This study investigates the magnitudes of peak pressures applied to the lateral side of the 5th metatarsal head (5MTH) and calcaneus (CC) by the uppers of footwear during sports movements. Method. A plantar pressure measuring system was adapted to fit into a sock covering the lateral aspect of the L5MTH and LCC. Six male participants (26.7 ± 2.4 years, 75.2 ± 5.5 kg) performed ten trials each of starting, stopping, sprinting, cutting and sidestepping at self-selected velocities, whilst wearing the pressure measuring device. Repeated measures ANOVA’s were used to examine differences between peak pressures at different aspects of the lateral side of the dorsum of the foot. Results. The results indicate significant differences (p 0.05) between peak pressures at the LCC compared to the L5MTH. Significant differences in peak pressure at the L5MTH were also found between movement strategies. No significant differences (p > 0.05) were reported at the LCC between different movements. Conclusions. The results identify a need for athletes pre-disposed to injuries in the uppers of the feet to consider the possible influence of footwear on the magnitudes of peak pressures applied to the lateral side of the dorsum of their feet.

3

New petrophysical model describing the pressure dependence of seismic velocity

100%

Dobróka M. , Somogyi Molnar J.

Acta Geophysica

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2012

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tom Vol. 60, no. 2

371-383

EN

Seismic data are increasingly applied to predict the characteristics of reservoirs, as their quality improves. Since the change of pressure is a major component in exploitation of reservoirs, a thorough understanding of the influence of pressure on seismic velocity is also important. In this study we introduce the first results of the developed petrophysical model which describes the pressure dependence of seismic velocity. The model is based on the idea that microcracks in rocks open and close under the change of pressure. Laboratory measurements are presented on several sandstone samples. Longitudinal wave velocities were measured at various incremental pressures increased from 0 to 20 MPa. During the measurements, the pulse transmission technique was used and the parameters of the model were determined by using a linearized inversion method. The inversion results proved that the proposed petrophysical model well applies in practice.

4

Protective role of mucin coat.

88%

Grygoruk C. , Mrugacz G. , Modliński, J.A , Gajda B. , Grad I. , Grusza M. , Sieczynski P.

Progress in Health Sciences

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2013

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tom 3

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nr 1

83-88

EN

Purpose: The present study was designed to examine the protective property of the mucin coat against pressure fluctuation. Materials and Methods: Thirty non-hatched rabbit blastocysts containing mucin coat and thirty mouse blastocysts were exposed to pressure fluctuations in in-vitro conditions. Morphological response of the blastocysts was assessed 5 and 60 minutes after exposition to pressure fluctuation. Results: Out of thirty mouse blastocysts there were 4 collapsed in 5th minute and 8 collapsed in the 60th minute. There were no collapsed rabbit blastocysts in 5th minute and only one in 60th minute. The difference between groups was statistically significant; p<0.05. Conclusions: Mucin coat has a unique property of protecting embryo from a deleterious effect of the rapid pressure fluctuations.

5

Large bending deformations of pressurized curved tubes

88%

Kolesnikov A. M.

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2011

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tom Vol. 63, nr 5-6

507-507

EN

In this paper, the problem of large pure bending deformations of membrane is considered. The membrane is a sector of torus with a closed cross-section. This membrane is called a curved tube for short. We consider the homogenous, incompressible, isotropic and hyperelastic material. The external load is a constant pressure and bending couples acting at the edges. The equilibrium equations reduce to ordinary differential equations. As an example, the membrane with a constant thickness and with a circular cross-section is investigated.

6

Quality of balance and pressure distribution beneath the foot during double-leg stance in young women

88%

Korvas P.

Physical Activity Review

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2019

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nr 7

71-79

EN

One from the important preconditions for optimal performance of all physical activities is a good quality of balance. Aim of Study: The study is focusing to find out the effect of pressure distribution beneath the foot on the balance and to compare the quality of balance in physically active and inactive young women. Material and Methods: Subjects of our study were two groups of healthy young women. A: physically active women (n=28; age 21.5 years; physical activity 8.8 hour/week), B: physically inactive (n=28; age 22,0 years; physical activity 1.3 hour/week). Three balance test we carried out: double-leg stance, eyes open (EO) and closed (EC) for 30 second, one-leg stance (right, left) for 10 second. Pressure walkway (FDM system, fi. Zebris) was used for data collection. Parameters: COPv: velocity of centre of pressure (mm/s), relative value of average pressure beneath the foot (%). Results: We found out that a physically active group of young women have significantly better results in all tests (p≤0.05). Both groups showed a similar tendency for significant deterioration of the results when elimination the support surface or the visual sensor in relation to the basic OE test. The differences in the distribution of pressures between the groups were significant in the M-L directions. Inactive women significantly more loaded the non-preferred leg and the rear part of the foot. Active women showed a more balanced stance in both directions, with a slight tendency to increase the loading on the front part of foot. Conclusion: It was confirmed that the group B has a partly worse characteristics of balance than physically active peers. The foot load strategy was less favourable for the group B; during EO. Only two interesting correlations were found in active women; between COPv and ratio of feet load. Remaining correlations to COPv were low.

7

High temperature and pressure effects on the elastic properties of B2 intermetallics AgRE

88%

Liu L. , Wu X. , Li W. , Wang R. , Liu Q.

Open Physics

|

2015

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tom 13

|

nr 1

EN

The high temperature and pressure effects on the elastic properties of the AgRE (RE=Sc, Tm, Er, Dy, Tb) intermetallic compounds with B2 structure have been performed from first principle calculations. For the temperature range 0-1000 K, the second order elastic constants for all the AgRE intermetallic compounds follow a normal behavior: they decrease with increasing temperature. The pressure dependence of the second order elastic constants has been investigated on the basis of the third order elastic constants. Temperature and pressure dependent elastic anisotropic parameters A have been calculated based on the temperature and pressure dependent elastic constants.

8

Pęcherzyki w szkliwie mołdawitów

88%

Brachaniec T. , Szczyrba M.

Acta Societatis Metheoriticae Polonorum

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2014

|

tom 5

17-20

EN

Bubbles in tektites can be formed by several different mechanisms. A review of published data has shown that the gas pressure in the bubbles is generally low. Composition of the contained gases published in most articles sharply differs from the composition of the terrestrial atmosphere.

9

Effect of Technological Parameters on the AlSi12 Alloy Microstructure During Crystallization Under Pressure

88%

Ščury J. , Brůna M. , Bolibruchová D. , Pastirčák R.

|

10

Pressure effect on mechanical properties of polymers

88%

Prodan T. , Emri I.

|

1999

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tom Vol. 4, no spec.

91-102

EN

Although high hydrostatic pressure commonly appears in demanding structural applications and during several manufacturing processes, there is little information available about its effect on material properties. For this reason, the Center for Experimental Mechanics has developed an apparatus that can characterize materials under the combined influence of pressure and temperature. Obtained measurements indicate that materials can be more accurately modeled, if both pressure and temperature are used, rather than temperature alone as it was historically done with the Williams-Landel-Ferry equation.

11

Ciśnienie porowe a stateczność ziemnych budowli piętrzących

75%

Fiedler K. , Stasierski J.

|

2004

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tom nr 7

50-53

PL

Przedstawiono wyniki świadczące o decydującym wpływie ciśnienia porowego wody gruntowej na poziom stateczności skarp budowli piętrzących. Stwierdzone różnice w wartościach miar stateczności dla tego samego schematu obliczeniowego przy zróznicowanych rozkładach ciśnień porowych wynoszą od 1,2 do 1,9, gdy wg obowiązujący przepisów powinny wynosić od 1,15 do 1,3.

12

Oczyszczanie ultradźwiękowe w roztworach wodnych a ciśnienie promieniowania ultradźwięków

75%

Niemczewski B.

|

2000

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tom Vol. 41, nr 12

45-47

PL

Badano ruchy wody, mierzone parciem na stożek pomiarowy radiometru, pod wpływem ciśnienia promieniowania ultradźwięków, w funkcji temperatury, przy czterech częstotliwościach ultradźwięków: 27 , 33, 37 i 60 kHz. Przy trzech z wymienionych częstotliwości, zgodnie z oczekiwaniami, ruchy te były niewielkie w stosunku do występujących w stosowanych do oczyszczania ultradźwiękowego rozpuszczalnikach organicznych. Natomiast przy częstotliwości 33 kHz, w temperaturach około 40-55°C, stwierdzono bardzo intensywne ciśnienie promieniowania.

EN

There have been made investigations of movements of water measured by pressure exerted on a measuring cone of an acousticc radiometer, induced by ultrasounds pressure versus temperature at four frequencies: 27, 33, 37 kHz. At three of the above frequencies, as expected, the movements were minor as compared to those in organic cleaning solvents whereas at 33 kHz and at about 40-55°C the pressure of ultrasounds was found to be very intense.

13

Wstępne modelowanie oddziaływania fali ciśnienia na półsferyczny element kompozytowy o zmiennej grubości

75%

Panowicz R. , Miedzińska D. , Niezgoda T. , Barnat W.

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2011

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tom R. 84, nr 2

142-142

PL

Przedstawiono wstępne wyniki modelowania oddziaływania fali ciśnienia powstałej z detonacji 100 g TNT na element kompozytowy o zmiennej grubości. Spowodowało to zmianę sztywności rozpatrywanego elementu. Są z tym związane również zmiany w zachowaniu obiektu poddanego dynamicznemu obciążeniu. Widoczne są charakterystyczne dla materiału kompozytowego linie pęknięć. Stopień zniszczenia elementu zależy od jego grubości. Zmieniając parametry geometryczne rozpatrywanego obiek- tu możemy sterować procesem jego niszczenia.

EN

The paper deals with the preliminary results of the finite element modelling of the blast wave effect on the half spherical composite elements with variable wall thickness. The change of the composite element thickness caused the differences in the sample stiffness. It also caused the changes in the researched object behavior under the dynamic load. The fracture lines, characteristic for the composite material, are visible in the finite element analysis results. It is possible to control the damage process of the researched object by changing its geometry parameters.

14

Pressure losses in a two-phase liquid-gas flow in minichannels

75%

Sowiński J.

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2007

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tom Vol. 28, z. 4

1147-1156

EN

Results of studies on pressure losses during two-phase liquid-gas flow in narrow vertical minichanels are discussed in the paper. The effect of liquid viscosity and channel gap width on pressure losses during two-phase flow was investigated. To describe experimental data, equations proposed by Chisholm as well as by Mishima and Hibiki were used.

PL

Przedstawiono wyniki badań strat ciśnienia podczas przepływów dwufazowych ciecz-gaz w wąskich pionowych minikanałach. Zbadano wpływ lepkości cieczy i grubości szczeliny kanału na straty ciśnienia w przepływie dwufazowym. Do opisu danych doświadczalnych zastosowano zależności Chisholma oraz Mishimy i Hibiki.

15

Methodology for comparison of hydrocode modelling with experiment for split Hopkinson pressure bar (SHPB) testing of soft materials

75%

Church P. , Pereira R. , Gould P. , Lewtas I.

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2011

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tom Vol. 59, iss. 4

251-262

EN

The objective of this work is to develop a technique for reliable comparison of simulations with SHPB data in order to validate material models for “soft” materials such as polymers. Comparison with an output stress-strain curve is not su?cient since there are many assumptions built into this analysis. Primarily these concern the notion that the specimen is in stress equilibrium and volume is conserved. The problem is that the choice of material model for the specimen in the simulation dictates how and when the specimen attains stress equilibrium. The main methodology is based on comparing the simulations with the raw strain gauge data on the input and output bars, which makes no assumptions about stress equilibrium. However, one has to account for the well documented Pochhammer-Chree oscillations and their effect on the specimen.

16

Effect of transverse surface roughness on the behaviour of squeeze film in a spherical bearing

75%

Andharia P. I. , Gupta J. L. , Deheri G. M.

|

1999

|

tom Vol. 4, no spec.

19-24

EN

Effect of transverse roughness on the behaviour of a hydrodynamic squeeze film between a non-rotating spherical surface and a hemispherical bearing under a steady load is discussed. It is assumed that the bearing surface as well as the surface of the approaching sphere have random roughness which is distributed throughout the surfaces. The stochastic film thickness characterizing the roughness is assumed to be symmetric with non-zero mean (a) and variance (s2). The modified Reynolds equation is solved and then the expressions for pressure, load carrying capacity and the response time are obtained and numerically computed. The results are presented both in graphical as well as tabular form. It is observed that the composite roughness of the surfaces affects the performance of the bearing adversely.

17

Innowacyjna metoda identyfikacji eksperymentalnej rozkładu nacisków w strefie interakcji gąsienicy elastomerowej z podłożem sztywnym

75%

Dudziński P. , Gładysiewicz A.

|

2007

|

tom R. 49, nr 3-4

172-176

PL

Stale rosnący wzrost zapotrzebowania na różne mobilne maszyny robocze i pojazdy przemysłowe, które często pracują na różnych podłożach sprawia, że w ostatnich latach gąsienice elastomerowe (przede wszystkim gumowe) coraz częściej zastępują tradycyjne gąsienice stalowe. Gąsienice elastomerowe wymagają jednak nowego podejścia teoretycznego i doświadczalnego, szczególnie w przypadku ruchu po sztywnych, utwardzonych podłożach, na których rzadko poruszają się gąsienice stalowe. W artykule zostanie przedstawiona innowacyjna metoda identyfikacji rozkładu nacisków pod gąsienicą gumową. Aby określić rozkład nacisków zbudowano nowe stanowisko badawcze. Opisane zostaną zarówno wyniki eksperymentalna jak i teoretyczne zależności. Na tle dotychczasowego stanu wiedzy i techniki wyniki te pokazują zjawiska i zależności, których charakter był dotychczas nie zarejestrowany, a na ich podstawie możliwe będzie lepsze niż dotychczas kształtowanie podwozia gąsienicowego.

EN

The increasing requirement for different mobile engineering machines and special vehicles, which often operate in various terrain, has caused that in the recent years rubber tracks much more often replace the steel ones. The rubber-track undercarriages require however new theoretical and experimental approach, especially in case of moving on rigid, paved ground, where steel tracks rarely move. In this paper an innovative method for identification of pressure distribution under rubber track will be presented. To investigate the pressure distribution a new test stand was built. Some of experimental as well as theoretical results will be described. In terms of the present-day state-of-the-art this results show new relationships and phenomena's, according to them a better understanding and construction of rubber tracked vehicles could be possible.

18

Badania parametrów ciśnieniowych w wybranych nowoczesnych aparatach udojowych

75%

Czarnociński F.

|

2008

|

tom R. 12, nr 4(102)

197-202

PL

Określono najważniejsze parametry ciśnieniowe w komorze podstrzykowej kubka udojowego czterech wybranych aparatów udojowych i przeprowadzono ich analizę porównawczą. Spadki podciśnienia są większe i gwałtowniejsze wtedy, gdy w tej samej parze kubków udojowych następuje zamykanie gum strzykowych. Najmniej korzystne warunki ciśnieniowe występowały w aparacie o najmniejszej pojemności kolektora. Najmniejsze wahania podciśnienia ssania ap, miały miejsce w aparacie udojowym FW, chociaż pojemność jego kolektora nie była największa.

EN

The most important pressure parameters in the under-teat chamber of the teat cup of four selected milking apparatuses were determined and comparative analysis was applied for them. A decrease in negative pressure was greater and more rapid when in the same pair of teat cups teat gums get closed. The least favourable pressure conditions occurred in the apparatus with the smallest collector capacity. The smallest fluctuations of ap, suction pressure occurred in the FW milking apparatus, although the capacity of its collector was not the greatest.

19

Numerical analysis of the effect of torispherical head on the buckling of pressure vessel

75%

Khoshravan M. R. , Rahmani A.

|

2009

|

tom Vol. 57, iss. 2

71-87

EN

The shape of end heads of a pressure vessel is usually torispherical. Buckling of this head is one of the most important points for designing of pressure vessels. This subject has been studied extensively since last years. In this field, the experimental methods are expensive and need a lot of time. In addition, because of lack of accuracy in the producing procedure, sometimes two models with identical geometry show different buckling behavior. Hence the use of finite element method in analyzing of buckling behavior of heads has a lot of benefits. In this dissertation, the finite element method has been used. Firstly with nonlinear buckling analysis, the effects of geometrical parameters such as thickness, knuckle radius and diameter of cylindrical part. on the buckling of heads have been studied, then the buckling behavior of different kinds of heads with identical geometry have been analyzed. For the nonlinear analysis we used the Arc Length method which can control the load level, the length of the displacement increment and the maximum displacement. The most important characteristic of this method is its ability to converge, even when the behavior is highly nonlinear. From the verification performed with the European Convention for Constructional Steelwork (ECCS) code, it has been confirmed that the nonlinear buckling analysis could assure accurate results for the buckling strength. In the case of internal pressure, it has been shown that initial imperfection had no effect on the pre-buckling behavior and buckling pressure of head; it just affects the post-buckling behavior.

20

Określenie rozkładów ciśnienia i składowych hydrodynamicznej siły wyporu smaru w łożysku ślizgowym o zarysie niekołowym smarowanym cieczą nienewtonowską

75%

Starczewski Z. , Korczak-Komorowski P.

|

2011

|

tom nr 6

15-18