Temat: changes in pressure - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: Monitorowanie i kontrola zmian ciśnienia atmosferycznego kopalni dla potrzeb bezpieczeństwa
Monitoring and control of changes in atmospheric pressure of a mine aimed at needs for safety
Autorzy:: Tomczyk, A.
Rutecki, K.
Powiązania:: https://bibliotekanauki.pl/articles/186595.pdf
Data publikacji:: 2009
Wydawca:: Sieć Badawcza Łukasiewicz - Instytut Technik Innowacyjnych EMAG
Tematy:: ciśnienie atmosferyczne kopalni
kontrola zmian ciśnienia atmosferycznego
monitorowanie zmian ciśnienia atmosferycznego
atmosphere pressure of a mine
control of changes in atmospheric pressure
monitoring of changes in atmospheric pressure
Opis:: Zmiana ciśnienia barometrycznego ma znaczący wpływ na migrację gazów zrobowych (tzw. oddychanie zrobów), stąd od wielu lat prowadzi się rejestrację zmian ciśnienia z sygnalizacją zniżki [2,5]. Dynamika zmian ciśnienia jest procesem wolnozmiennym, jednak każdego dnia obserwuje się krótkookresowe skoki ciśnienia. W artykule przedstawiono wybrane metody analizy trendu zmian dla szeregu czasowego jakim jest zarejestrowany przebieg zmian ciśnienia, które następnie poddano weryfikacji skuteczności działania na przykładzie rzeczywistych danych pomiarowych.
A change in barometric pressure has a significant impact on migration of goaf gases (so called goaf breathing). Hence for many years there have been recording the changes in pressure allowing for drops in pressure [2, 5]. Dynamics of changes in pressure is a low-variable process; however every day one may observe short-period pressure jumps. Selected methods of analysis of trends in changes in time series in form of a recorded course of changes in pressure have been presented in the paper. Next the methods have been verified regarding their effectiveness exemplified by real measuring data.
Źródło:: Mechanizacja i Automatyzacja Górnictwa; 2009, R. 47, nr 7, 7; 99-107
0208-7448
Pojawia się w:: Mechanizacja i Automatyzacja Górnictwa
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: O "arktycznych" i "atlantyckich" mechanizmach sterujących zmiennością temperatury powietrza na obszarze Europy i północo-zachodniej Azji
On "Arctic" and "Atlantic" mechanisms controlling the changeability in air temperature in the region of Europe and NW Asia
Autorzy:: Marsz, A. A.
Styszyńska, A.
Powiązania:: https://bibliotekanauki.pl/articles/260919.pdf
Data publikacji:: 2006
Wydawca:: Stowarzyszenie Klimatologów Polskich
Tematy:: zmiany temperatury powietrza
zmiany temperatury wody powierzchniowej
NAO
Oscylacja Eurazjatycka
AO
Arktyka Atlantycka
NW Azja
Europa
Atlantyk Północny
NW Asia
Europe
changes in pressure
changes in air temperature
Opis:: Praca omawia wpływ zmian ciśnienia atmosferycznego w Arktyce Atlantyckiej (dalej AA) na kształtowanie zmienności temperatury powietrza na obszarze Europy (na N od 40°N) i NW Azji (do 120°E). Wpływ zmian ciśnienia w AA na temperaturę powietrza zaznacza się we wszystkich, z wyjątkiem czerwca, miesiącach roku, tworząc charakterystyczny cykl z maksimum siły oddziaływania zimą. Zimowe (01-03) zmiany ciśnienia w AA objaśniają od kilkunastu do ponad 60% zmienności temperatury rocznej (z maksimum na obszarze wokół-bałtyckim; 1951-2000). W pracy analizuje się współdziałanie zmian ciśnienia w Arktyce Atlantyckiej ze zmianami ciśnienia w Wyżu Syberyjskim w kształtowaniu zmienności temperatury powietrza na obszarze Europy i NW Azji. Dyskutuje się również kwestie związków zmian ciśnienia w AA z NAO, AO oraz frekwencją makrotypów cyrkulacji środkowotroposferycznej wg klasyfikacji Wangengejma-Girsa. Wyniki analiz wykazują, że o zimowych zmianach ciśnienia w AA decyduje wcześniejszy rozkład zasobów ciepła w wodach Atlantyku Północnego.
The research on relations between climatic elements of Europe and the Arctic has indicated that there are significant correlations between changes in atmospheric pressure in the Atlantic part of the Arctic and air temperature in northern Europe and NW Asia. The strongest correlations are observed between changes in pressure over relatively small area of the Atlantic part of the Arctic (72.5 - 80.0°N, 10.0 - 25.0°E), in addition, the point over which changes in pressure explain most of changes in air temperature is located 75.0°N, 015.0°E. Pressure at this point is further referred as P[75,15] with an index denoting a month (e.g. P[75,15]03 denotes mean pressure in March and P[75,15]01-03 defines mean pressure at this point from the period January till March). Over the Atlantic part of the Arctic within the pressure area there is no marked climatic centre which could be regarded as the centre of atmospheric activity. The research made use of monthly series of SLP values (reanalysis: set NOAA.NCEP-NCAR. CDAS-1.MONTHLY.Intrinsic.MSL.pressure) and the values of monthly air temperature from 211 stations (Fig. 1). The observational period common for both elements covers 50 years, i.e. the period from January 1951 to December 2000. The character of correlations between P[75,15] and air temperature in the following months, from June to May, and their spatial distribution have been presented by isocorrelates maps (Fig. 2). Changes in the strength of correlations between P[75,15] and the temperature over Europe and NW Asia form a clear annual cycle interrupted in June. In June the correlations between P[75,15] and air temperature became very weak and not significant over the most of the area and not continuous in space. During the months after June these correlations got stronger and stronger reaching their maximum during cold season (from November to April). This maximum is located in the region adjacent to the Baltic Sea, where annual and winter (01-03) changes in P[75,15] explain from more than 60% to 50% of annual temperature variances (Fig. 3) The strongest correlation between P[75,15] and air temperature in Siberia is located N of Baikal, where winter (01-03) changes in P[75,15] explain 43-45% of annual temperature variances. At the end of the cold season a visible delay of the decrease in the strength of correlation is observed in the region of Siberia in relation to the European region (in Europe after March, in Siberia after April). Variability in winter and annual values of pressure at 75°N, 015°E also indicates relatively strong correlations with the changeability in temperature of the warmest month in the year in the west and central region of Europe. The annual variability in P[75,15] explains from 40% to 30% changeability of maximum temperature in the region extending from the Atlantic coast of France to central Germany. This belt extends farther east towards the Baltic Sea. The latter correlation has not been explained in this work. The analysis of correlations of changes in pressure at 75°N, 15°E with NAO indicates to the occurrence of statistically significant correlations during months of cold season in the year (October - March, May and June; Tab. 2). Similar analysis of correlations of changes in P[75,15] with AO index (Arctic Oscillation) shows strong and highly statistically significant correlations in all months of the year with maximum falling in January and February. Annual changes in P[75,15], i.e. in pressure at one point explain 73% annual changeability in AO index (r = 0.86) and the winter changeability in (December - March) P[75,15] explains 78% of winter changeability in AO index (r = 0.88) which is the first vector EOF of pressure field (1000 hPa) covering the area from 20°N to the North Pole (90°N), that is the most area of the Northern Hemisphere. This analysis shows that the changes in pressure at the point 75°N, 15°E result in intensification of cyclogenesis over west and central part of the North Atlantic and the consequent long waves (waves of W type following Wangengejm-Girs classification) cause that anticyclones formed over the Atlantic will direct towards Fram Strait through the region of Iceland. The above process has nothing or almost nothing to do with the form of changeability in polar strato-spheric eddy, as assumed by Tomphson and Wallace (1998, 2000, Thompson, Wallace, Hegerl 2000) to be essential for the Arctic Oscillation functioning. Occurrence of correlations between P[75,15] and air temperature over vast areas from 10°W to 130°E suggests that also changes in pressure in the Siberian High are engaged in this process. Theanalysis shows that in a yearly process, changes in pressure in the Atlantic part of the Arctic and in the Siberian High occur in opposite phases (see Tab.1). Barometric gradient between the Atlantic part of the Arctic and the Siberian High becomes extremely strong during the cold season of the year contributing to "pumping" air from eastern Europe to the far end of the Siberia. During the summer season the gradient becomes very weak as the about-turn takes place. The cooperation of changes in pressure in the Atlantic part of the Arctic and pressure in region located farther Baikal -- Mongolia results in very strong oscillation which partly can be identified with Euro-Asian Oscillation (Monahan et al. 2000). During winter season interannual changes in pressure in the Siberian High are relatively small and explain 10.4% variances of barometric gradient between P[75,15] and point 45°N, 110°E (the region of the centre of the Siberian High), whereas the interannual changes in P[75,15] explain 77.5% of variances in this gradient. This means that in the cold season of the year the intensity of air transfer from the west towards Asian land depends on variability in pressure in the Atlantic part of the Arctic. Because in the months of the cold season of the year NAO is the strongest and significantly correlated with changes in P[75,15] therefore, a two-element, with the same phase "conveyor belt" is formed, which during positive phases of NAO transfers the air from over the Atlantic to Europe (NAO) and then towards and into the Siberia (Euro-Asian Oscillation). P[75,15] during cold season months of the year (01-03) indicates statistically significant negative trend (-0.153 hPa/year; p < 0.006) which enables to state that the observed, over the years 1951-2000, increase in air temperature in the Siberia can be, in great extent, attributed to the activity of the above described circulation mechanism. The analysis of reasons for interannual changes in P[75,15] has indicated that there are strong and significant correlations between variability in P[75,15] and the earlier variability in the thermal conditions of the Atlantic Ocean. A very important role in this relation plays thermal condition of three sea areas, i.e. waters of the subtropical region of central part of the North Atlantic (characterized by SST anomalies in grid 34°N, 40°W from August and September), waters of the middle latitudes zone of the central part of the North Atlantic (characterized by SST anomalies from August and September in grid 54°N, 30°W) and waters of the North Atlantic Current from the approach to the Farero-Shetland Passage (characterized by SST anomalies from January and April in grid 60°N, 10°W). Thermal state of these three sea water areas (see formulas [1] and [2]) explains 58% changeability in P[75,15] which will be observed in the following winter (DJFM). The cause of the described correlation is attributed to the fact that the earlier thermal state of the above mentioned sea areas controls the occurrence of long waves, of W and E Wangengejm-Girs type during the following winter. Further, these waves influence the occurrence of low cyclones over the Atlantic part of the Arctic during winter resulting in adequate changes in mean monthly pressure. As a result, it can be stated that the interannual variability in air temperature over vast areas of Europe and over NW Asia is influenced by the processes observed over the North Atlantic and the Atlantic part of the Arctic. The research covers years 1971-2003 (ano-malies in SST taken from 1970-2002) due to the fact that the data have been not only accessible and reliable but also homogeneous with respect to climatological data of SST (CACSST data set (Reynolds and Roberts 1987, Reynolds 1988) and SST OI v.1. (Reynolds et al. 2002).
Źródło:: Problemy Klimatologii Polarnej; 2006, 16; 47-89
1234-0715
Pojawia się w:: Problemy Klimatologii Polarnej
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: 3D hydrodynamic pressure in gap height direction for cylindrical bearing viscoelastic lubrication
Autorzy:: Wierzcholski, K.
Powiązania:: https://bibliotekanauki.pl/articles/246411.pdf
Data publikacji:: 2013
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: pressure changes in gap height direction
HDD micro-bearings
viscoelastic lubrication
Źródło:: Journal of KONES; 2013, 20, 1; 367-374
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Recurrent nets for tribology solutions
Autorzy:: Wierzcholski, K.
Powiązania:: https://bibliotekanauki.pl/articles/244153.pdf
Data publikacji:: 2013
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: pressure changes in gap height direction
HDD micro-bearings
viscoelastic lubrication
Opis:: The contemporary problems of numerical calculations ocurring in powertrain tribology and transport problems demand the more and more exactness for obtained results.Moreover in performed calculations very important is the convergence, stability and reliability of the gained numerical values. The main scientific topic of the presented paper concerns the method of the determination of the optimum net for numerical calculations of partial difference and recurrence equations. The abovementioned optimum difference and recurrence method is referring to the stability of obtained particular and general numerical solutions and assures the convergence process of obtained calculation values. The Unit Net Region (UNR) was assumed at first for Laplace Operator. The optimum of the nod geometry localization was examined at first for UNR. The optimization index is defined and derived for UNR to determine the most useful net among the various geometries of the nods localization during the difference methods performances of partial recurrence numerical calculations. In the next considerations had been proved the corollary, where taking into account the optimum UNR, we can create optimum nets for other numerous partial difference and recurrence equations in discrete spaces. For example the numerous calculation results of presented optimum net for recurrent calculations are applied for numerical solutions of a Reynolds partial recurrence equation with variable coefficients in curvilinear orthogonal coordinates for curvilinear boundary conditions, and for other numerical problems occurring in applied and hydrodynamics.
Źródło:: Journal of KONES; 2013, 20, 2; 401-408
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: The influence of oil’s exploitation time on load carrying capacity in a slider bearing
Autorzy:: Sikora, G.
Miszczak, A.
Powiązania:: https://bibliotekanauki.pl/articles/244279.pdf
Data publikacji:: 2015
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: oil ageing
numerical calculations
Reynolds equation
pressure distribution
load carrying capacities
viscosity changes in time
Opis:: In this paper, authors are presenting conclusions of the numerical calculations of pressure distribution and capacity in a slider bearing with taking changes of oil viscosity in exploitation time into account. Changes of the engine oil’s viscosity, which depend on the exploitation time, were determined on Haake Mars III rheometer and the conclusions were published in Solid State Phenomena and Logistyka in 2015. Numerical calculations were performed by solving of Reynolds equation, using finite difference method and own calculation procedures in Mathcad 15. Reynolds equation was developed by solving the continuity equation and the momentum conservation equation from the fundamentals. For the considerations, the laminar and stationary lubricating of the slider bearing of finite length and full angle of wrap were taken. Assumption of the stationary flow concerns lack of changes in flow parameters in short period of considered phenomena, f. ex. in one hour. Smooth and non-porous bushing were assumed. The aim of this paper was preliminary estimation of influence of viscosity changes in the exploitation time on the load carrying capacities of the cross slider bearing. Wherefore, the viscosity changes dependence on the pressure, temperature and also shear rate, were not taken into account. The basic equations were developed to the non-dimensional form and estimated according to the thin layer theory. In the calculations, the Reynolds boundary conditions concerning pressure distribution were taken into account. Preliminary calculations were performed for different models of viscosity changes in time and circumstances, where the viscosity increases and decreases in exploitation time.
Źródło:: Journal of KONES; 2015, 22, 3; 207-212
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Operating parameters of slide micro – bearings with consideration of oil temperature changes and micro - grooves on sleeve surface
Autorzy:: Miszczak, A.
Powiązania:: https://bibliotekanauki.pl/articles/247490.pdf
Data publikacji:: 2012
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: HDD micro-bearings
micro-grooved surfaces
oil viscosity changes in gap height
hydrodynamic pressure
friction forces
load carrying capacity
Opis:: In this paper author presents results of numerical calculations of hydrodynamic pressure distribution in bearing gap, load-carrying capacity, friction force and friction coefficient of slide micro-bearing considering the influence of lubricating oil temperature changes and also taking into account the influence of micro-grooves, which occur on sleeve internal surface. The micro-grooves on that surface are in longitudinal direction. The equation, which describes a bearing gap with micro-grooves on sleeve surface, was adopted from prof. K Wierzcholski's investigations. In very thin gap height of cylindrical micro-bearings, large gradients of temperature can be observed. This causes significant changes of oil dynamic viscosity in the gap height direction. According to this, oil flow velocity, friction forces, and a hydrodynamic pressure during the micro-bearing operation are changing. Up to now the influence of temperature on oil viscosity changes and due to this, on hydrodynamic pressure and on load carrying capacity in cylindrical micro-bearing gap in numerical way were not considered yet. The numerical calculations were performed with the use of Mathcad 14. The finite differences method and own computational procedures were implemented. The calculations were begun by solving the Reynolds' equation, assuming, that the dynamic viscosity is constant. After calculating the hydrodynamic pressure distribution, the temperature distribution in lubricating oil was determined. The obtained function of temperature was used to describe the viscosity changes with temperature. Next step involved determining the hydrodynamic pressure distribution taking into account the viscosity dependence on temperature, and then new distribution of temperature and again new values of viscosity were calculated. Calculations were repeated until assumed convergence and accuracy were reached. The friction force depends on pressure gradient and rotational motion of bearing journal. Part of friction force, which resulting from the pressure gradient, is determined for the area, where the oil film occurs, i.e. from omega p to omega k. Part of friction force, which is related to journal motion, is determined for full wrap angle, i.e. from 0 to 2 pi. The results were presented in the form of graphs, for eccentricity ratio gamma from 0.1 to 0.9, for dimensionless length of the bearing L1=1/4. In numerical calculations were used the theoretical considerations and solutions presented in papers of K. Wierzcholski and A. Miszczak.
Źródło:: Journal of KONES; 2012, 19, 2; 329-336
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Exclusion of lands from agricultural production and urban pressure – case study
Wyłączenia gruntów z produkcji rolnej a zjawisko presji urbanistycznej – case study
Autorzy:: Prus, B.
Powiązania:: https://bibliotekanauki.pl/articles/100464.pdf
Data publikacji:: 2016
Wydawca:: Uniwersytet Rolniczy im. Hugona Kołłątaja w Krakowie
Tematy:: historical changes in land use
local changes in land use
urban pressure
original use
target use
objects’ classification
spatial taxonomy
historyczne zmiany użytkowania gruntów
lokalne zmiany użytkowania gruntów
presja urbanistyczna
użytkowanie pierwotne
użytkowanie docelowe
klasyfikacja obiektów
taksonomia przestrzenna
Opis:: Though agricultural lands are subject to legal protection limiting their use for non-agricultural purposes, recent research shows that investment areas are becoming larger at the cost of agricultural production areas. The analysis of cases in which lands have been excluded from agricultural production within Ropczyce-Sędziszów district (powiat), covering the period of 15 years, confirms that the change of area of particular lands is taking place. The biggest change affected grasslands and arable lands. The lands excluded from agricultural production are transformed into single-family housing, recreational and communication areas. Moreover the research allowed to show similarities in communes (gminy) with respect to lands excluded from agricultural production. The communes were singled out that were homogeneous as regards exclusion carried out in years 1999–2014. The choice of a research unit – Ropczyce-Sędziszów district – is determined by accessibility of data regarding exclusions and the fact the district is regarded as a unit with an average outlook for socioeconomic development. Simple statistical methods, quantitative analyses and a method of spatial taxonomy were used in the research.
Pomimo, że grunty rolne podlegają prawnej ochronie polegającej na ograniczaniu przeznaczania na cele nierolnicze, badania wskazują na rosnącą powierzchnię terenów inwestycyjnych kosztem rolniczej przestrzeni produkcyjnej. Analiza przypadków wyłączeń gruntów z produkcji na terenie powiatu ropczycko-sędziszowskiego, obejmująca okres 15 lat, potwierdza zmiany w powierzchniach poszczególnych użytków gruntowych. Największym zmianom podlega powierzchnia użytków zielonych oraz gruntów ornych. Grunty wyłączone z produkcji zamieniane są na obszary zabudowy mieszkaniowej jednorodzinnej, rekreacyjnej oraz tereny komunikacyjne. Ponadto badania pozwoliły na określenie podobieństwa gmin w zakresie gruntów wyłączanych z produkcji rolnej. Wydzielono gminy jednorodne pod względem przeprowadzonych w latach 1999-2014 wyłączeń. Wybór jednostki badawczej (powiatu ropczycko-sędziszowskiego) uwarunkowany był możliwością pozyskania danych dotyczących wyłączeń oraz faktem, że powiat ten jest zaliczany do jednostek o przeciętnych warunkach rozwoju społeczno-gospodarczego. W badaniach wykorzystane zostały proste metody statystyczne, analizy ilościowe oraz metoda taksonomii przestrzennej.
Źródło:: Geomatics, Landmanagement and Landscape; 2016, 4; 169-182
2300-1496
Pojawia się w:: Geomatics, Landmanagement and Landscape
Dostawca treści:: Biblioteka Nauki

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