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Tytuł:
Epichloe (formerly Neotyphodium) fungal endophytes increase adaptation of cool-season perennial grasses to environmental stresses
Epichloe (dawniej Neotyphodium) grzybowe endofyty zwiększają adaptacje traw zimotrwałych do stresów środowiskowych
Autorzy:
Malinowski, D.P.
Belesky, D.P.
Powiązania:
https://bibliotekanauki.pl/articles/26839.pdf
Data publikacji:
2019
Wydawca:
Polskie Towarzystwo Botaniczne
Opis:
Many cool-season grass species have evolved with asexual, nonsymptomatic fungal endophytes of the genus Epichloë (formerly Neotyphodium) of the family Clavicipitaceae. These associations range from parasitic to mutualistic and have dramatic effects on grass host chemistry, increasing resistance to abiotic (drought, soil mineral imbalance) and biotic (vertebrate and invertebrate herbivory, nematodes, plant pathogens, plant competition) stresses. Native endophyte strains produce a range of bioprotective alkaloid and other nonalkaloid secondary compounds, several of them known to have detrimental effects on grazing animals. In the past two decades, epichloid endophyte strains have been selected with marginal or no capacity of producing ergot and/or lolitrem alkaloids. These novel endophyte strains have been introduced to several grass cultivars with the idea to increase grass host resistance to abiotic stresses without hindering grazing livestock, and abiotic stresses to ensure high competitive ability of symbiotic grass cultivars. In this presentation, we discuss mechanisms underlying the competitiveness of epichloid endophyte/grass associations and consequences of endophyte infection for grassland ecosystem functions.
W trakcie ewolucji, wiele gatunków traw zimotrwałych ukształtowało symbiozy z bezpłciowymi, bezobjawowymi grzybowymi endofytami z rodzaju Epichloë (dawniej Neotyphodium ) z rodziny Clavicipitaceae. Zależności pomiędzy tymi organizmami obejmują zarówno relacje pasożytnicze jak i mutualistyczne, i mają ogromny wpływ na szlaki metaboliczne traw, np. zwiększają odporność na wiele stresów środowiskowych (susza, zaburzenia równowagi mineralnej w glebie) i biotycznych (uszkodzenia liści przez zwierzęta kręgowe i bezkręgowe, pasożytnicze nicienie, patogeny i konkurencję z innymi roślinami). Niektóre szczepy endofytów wytwarzają szereg alkaloidów i innych wtórnych związków chemicznych, które mogą mieć szkodliwy wpływ na zwierzęta wypasane na symbiotycznych trawach. W ciągu ostatnich dwóch dekad zostały wyizolowane szczepy endofytów, które nie produkują związków chemicznych szkodliwych dla zwierząt, tj. alkaloidy z grupy ergot czy lolitrem. Te nowe szczepy endofitów zostały wprowadzone do kilku odmian traw pastwiskowych z myślą o zwiększeniu ich odporności na stresy środo- wiskowe, ale bez negatywnego wpływu na wypasane zwierzęta hodowlane w celu zapewnienia wysokiej zdolności konkurowania symbiotycznych odmian traw z chwastami. W niniejszej pracy omawiamy mechanizmy odpowiedzialne za większą zdolność konkurencyjną symbiotycznych traw oraz konsekwencje tej symbiozy dla ekosystemów roślinnych.
Źródło:
Acta Agrobotanica; 2019, 72, 2
0065-0951
2300-357X
Pojawia się w:
Acta Agrobotanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Grassland communities in the USA and expected trends associated with climate change
Zbiorowiska łąkowe w USA i spodziewane kierunki ich przekształceń związane ze zmianami klimatycznymi
Autorzy:
Belesky, D.P.
Malinowski, D.P.
Powiązania:
https://bibliotekanauki.pl/articles/27260.pdf
Data publikacji:
2016
Wydawca:
Polskie Towarzystwo Botaniczne
Opis:
Grasslands, including managed grazinglands, represent one of the largest ecosystems on the planet. Managed grazinglands in particular tend to occupy marginal climatic and edaphic resource zones, thus exacerbating responses in net primary productivity relative to changes in system resources, including anthropogenic factors. Climate dynamism, as evident from the fossil record, appears to be a putative feature of our planet. Recent global trends in temperature and precipitation patterns seem to differ from long-term patterns and have been associated with human activities linked with increased greenhouse gas emissions; specifically CO2. Thus grasslands, with their diverse floristic components, and interaction with and dependence upon herbivores, have a remarkable ability to persist and sustain productivity in response to changing resource conditions. This resistance and resilience to change, including uncertain long-term weather conditions, establishes managed grasslands as an important means of protecting food security. We review responses of grassland communities across regions of the USA and consider the responses in productivity and system function with respect to climatic variation. Research is needed to identify plant resources and management technologies that strengthen our ability to capitalize upon physiological and anatomical features prevalent in grassland communities associated with varying growing conditions.
Trwałe użytki zielone, w tym pastwiska, należą do ekosystemów trawiastych i zajmują duże obszary w strefach klimatycznych, gdzie niemożliwy jest rozwój formacji drzewiastych. Pastwiska na ogół zajmują regiony marginalne pod względem klimatycznym i glebowym, co dodatkowo przyczynia się do pogarszania ich podstawowej wydajności w stosunku do zasobów systemowych, w tym czynników antropogenicznych. Dynamika klimatu, jak wynika z danych kopalnych, jest trwałą cechą zmian zachodzących na naszej planecie. Notowane obecnie wzorce temperatury i opadów różnią się od danych wieloletnich, co wiąże się z działalnością człowieka i wzrostem emisji gazów cieplarnianych, w szczególności CO2. Trwałe użytki zielone, z ich różnorodnym składem florystycznym i oddziaływaniem i/lub uzależnieniem od roślinożerców, mają szczególną zdolność do przetrwania i utrzymywania produktywności przy zmieniających się zasobach siedliska. Ta odporność i elastyczność na zmiany długoterminowe oraz niepewne warunki pogodowe, sprawia że trwałe użytki zielone są istotnym elementem dla ochrony i zapewnienia bezpieczeństwa żywnościowego. W prezentowanej pracy dokonano przeglądu trwałych użytków zielonych w poszczególnych regionach USA oraz oceniano ich produkcyjność i funkcjonowanie w odniesieniu do zmian klimatycznych. Niezbędne są badania w celu identyfikacji zasobów roślinnych i opracowanie technologii produkcji opartych o rozpoznanie fizjologicznych i anatomicznych cech roślinności. Technologie te umożliwiają, w powiązaniu z różnymi warunkami uprawy, wykorzystanie potencjalnych możliwości zbiorowisk trawiastych.
Źródło:
Acta Agrobotanica; 2016, 69, 2
0065-0951
2300-357X
Pojawia się w:
Acta Agrobotanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Relevance of Error Analysis in Graphical Symbols Evaluation
Autorzy:
Piamonte, D. P. T.
Powiązania:
https://bibliotekanauki.pl/articles/90739.pdf
Data publikacji:
1999
Wydawca:
Centralny Instytut Ochrony Pracy
Tematy:
symbols
videophone icons
empirical testing methods
wideotelefonia
badania empiryczne
symbole graficzne
Opis:
In an increasing number of modern tools and devices, small graphical symbols appear simultaneously in sets as parts of the human-machine interfaces. The presence of each symbol can influence the other’s recognis ability and correct association to its intended referents. Thus, aside from correct associations, it is equally important to perform certain error analysis of the wrong answers, misses, confusions, and even lack of answers. This research aimed to show how such error analyses could be valuable in evaluating graphical symbols especially across potentially different user groups. The study tested 3 sets of icons representing 7 videophone functions. The methods involved parameters such as hits, confusions, missing values, and misses. The association tests showed similar hit rates of most symbols across the majority of the participant groups. However, exploring the error patterns helped detect differences in the graphical symbols’ performances between participant groups, which otherwise seemed to have similar levels of recognition. These are very valuable not only in determining the symbols to be retained, replaced, or re-designed, but also in formulating instructions and other aids in learning to use new products faster and more satisfactorily.
Źródło:
International Journal of Occupational Safety and Ergonomics; 1999, 5, 4; 513-528
1080-3548
Pojawia się w:
International Journal of Occupational Safety and Ergonomics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Scattering of oblique water waves by an infinite step
Autorzy:
Dolai, P.
Dolai, D. P.
Powiązania:
https://bibliotekanauki.pl/articles/265749.pdf
Data publikacji:
2018
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
aproksymacja Galerkina
wielomian Gegenbauera
współczynnik transmisji
infinite step
Havelock expansion
Galerkin approximation
Gegenbauer polynomial
reflection and transmission coefficients
Opis:
The present paper is concerned with the problem of scattering of obliquely incident surface water wave train passing over a step bottom between the regions of finite and infinite depth. Havelock expansions of water wave potentials are used in the mathematical analysis to obtain the physical parameters reflection and transmission coefficients in terms of integrals. Appropriate multi-term Galerkin approximations involving ultra spherical Gegenbauer polynomials are utilized to obtain very accurate numerical estimates for reflection and transmission coefficients. The numerical results are illustrated in tables.
Źródło:
International Journal of Applied Mechanics and Engineering; 2018, 23, 2; 327-338
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Internal wave diffraction by a strip of an elastic plate on the surface of a stratified fluid
Autorzy:
Dolai, P.
Dolai, D. P.
Powiązania:
https://bibliotekanauki.pl/articles/265771.pdf
Data publikacji:
2013
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
równanie Kleina-Gordona
płyn warstwowy
metoda Wienera-Hopfa
stratified fluid
Klein-Gordon equation
Wiener-Hopf technique
steepest descent method
Opis:
The problem of internal wave diffraction by a strip of an elastic plate of finite width present on the surface of an exponentially stratified liquid is investigated in this paper. Assuming linear theory, the problem is formulated in terms of a function related to the stream function describing the motion in the liquid. The related boundary value problem involves a hyperbolic type partial differential equation (PDE), known as the Klein Gordon equation. The method of Wiener-Hopf is utilized in the mathematical analysis to a slightly generalized boundary value problem (BVP) by introducing a small parameter, and the problem is solved approximately for large width of the plate. In the final results, this small parameter is made to tend to zero. The diffracted field is obtained in terms of integrals, which are then evaluated asymptotically in different regions for a large distance from the edges of the plate and the results are interpreted physically.
Źródło:
International Journal of Applied Mechanics and Engineering; 2013, 18, 1; 5-26
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Technical and economic analysis of the impact of compressors installed at well clusters
Autorzy:
Foidas, I.
Stefanescu, D. P.
Powiązania:
https://bibliotekanauki.pl/articles/298607.pdf
Data publikacji:
2014
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
dynamic pressures
suction pressures
group compressor
cash flow
Opis:
The current stage of mature gas fields exploitation is characterized by increasing the efforts for maintaining the wells in production, in order to maximize the gas recovery factor in conditions of economic profitability. In this respect, a permanent concern of the specialists in this domain is represented by the adjustment of the compression capacities with the dynamics of the energetic parameters of every well belonging to these fields. This assumes the compression units installing as close to the well head in order to decrease the dynamic pressure, allowing the gas ratę increasing. On the other hand, decreasing the dynamic pressure at the well head, results also in reducing the minimum gas rate necessary for removal the liquid accumulated at the wells bottom, avoiding thereby the risk of the wells flooding. The pilot project of installing the portable compressors at the level of some gas groups operated by Romgaz, was a real success, the future perspectives regarding the production enhancing and revenue growth, based on this technology, being certainly.
Źródło:
AGH Drilling, Oil, Gas; 2014, 31, 2; 263-270
2299-4157
2300-7052
Pojawia się w:
AGH Drilling, Oil, Gas
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The oldest record of Juniperoxylon, a cupressaceous fossil wood from the Middle Triassic of Argentina
Autorzy:
Ruiz, D.P.
Bodnar, J.
Powiązania:
https://bibliotekanauki.pl/articles/22790.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Opis:
One of the oldest species of fossil woods with affinities to Cupressaceae is Cupressinoxylon zamunerae from the Ladinian, Middle Triassic of Argentina, but the generic assignment of this species was a subject of debate. The main character that is in conflict with Cupressinoxylon is the presence of ray tracheids in C. zamunerae, a character absent in the original diagnosis of the genus. In order to clarify this issue, original microscopic slides of the type materials were restudied herein, and also new sections and SEM samples were observed. The supposed ray tracheids turned out to be parenchyma cells. A new combination is established, relating C. zamunerae to Juniperoxylon due to the markedly pitted ray parenchyma cells walls. This fossil species is the first mention of Juniperoxylon from the Mesozoic of Gondwana and the oldest record worldwide until date.
Źródło:
Acta Palaeontologica Polonica; 2019, 64, 3
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Composition of Arithmetical functions with generalization of perfect and related numbers
Autorzy:
Shukla, D.P.
Yadav, Shikha
Powiązania:
https://bibliotekanauki.pl/articles/746376.pdf
Data publikacji:
2012
Wydawca:
Polskie Towarzystwo Matematyczne
Tematy:
Arithmetic Functions
Abundent numbers
Deficient numbers
Inequalities
Geometric Numbers
Harmonic Numbers
Opis:
In this paper we have studied the deficient and abundent numbers connected with the composition of \(\varphi\), \(\varphi^*\), \(\sigma\), \(\sigma^*\) and \(\psi\) arithmetical functions, where \(\varphi\) is Euler totient, \(\varphi^*\) is unitary totient, \(\sigma\) is sum of divisor, \(\sigma^*\) is unitary sum of divisor and \(\psi\) is Dedekind's function. In 1988, J. Sandor conjectured that \(\psi(\varphi(m)) \geq m\), for all \(m\), all odd \(m\) and proved that this conjecture is equivalent to \(\psi(\varphi(m)) \geq \frac{m}{2}\), we have studied this equivalent conjecture. Further, a necessary and sufficient conditions of primitivity for unitary r-deficient numbers and unitary totient r-deficient numbers have been obtained. We have discussed the generalization of perfect numbers for an arithmetical function \(E_\alpha\).
Źródło:
Commentationes Mathematicae; 2012, 52, 2
0373-8299
Pojawia się w:
Commentationes Mathematicae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Generalized Perfect Numbers
Autorzy:
Shukla, D.P.
Yadav, Shikha
Powiązania:
https://bibliotekanauki.pl/articles/746659.pdf
Data publikacji:
2013
Wydawca:
Polskie Towarzystwo Matematyczne
Tematy:
Prime numbers, perfect numbers, super perfect numbers, arithmetical Functions
Opis:
In this paper a modified form of perfect numbers called \((p,q)\)+ perfect numbers and their properties with examples have been discussed. Further properties of \(\sigma _{+}\) arithmetical function have been discussed and on its basis a modified form of perfect number called \((p,q)\)+ super perfect numbers have been discussed. A modified form of perfect number called \((p,0)\)-perfect and their characterization has been studied. In the end of this paper almost super perfect numbers have been introduced.
Źródło:
Commentationes Mathematicae; 2013, 53, 1
0373-8299
Pojawia się w:
Commentationes Mathematicae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Edge waves over a shelf
Autorzy:
Dolai, P.
Dolai, D. P.
Powiązania:
https://bibliotekanauki.pl/articles/264611.pdf
Data publikacji:
2019
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
fala brzegowa
wielomian Gegenbauera
relacja dyspersji
shelf
edge wave
Havelock expansion
Galerkin approximation
Gegenbauer polynomial
dispersion relation
Opis:
The problem considered in this paper is the derivation of properties of edge waves travelling along a submerged horizontal shelf. The problem is formulated within the framework of the linearized theory of water waves and Havelock expansions of water wave potentials are used in the mathematical analysis to obtain the dispersion relation for edge waves in terms of an integral. Appropriate multi-term Galerkin approximations involving ultra spherical Gegenbauer polynomials are utilized to obtain a very accurate numerical estimate for the integral and hence to derive the properties of edge waves over a shelf. The numerical results are illustrated in a table and curves are presented showing the variation of frequency of the edge waves with the width of the shelf.
Źródło:
International Journal of Applied Mechanics and Engineering; 2019, 24, 2; 453-460
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Occupational Safety of Farmers in the Vegetable Industry
Autorzy:
Lu, J. L. D. P.
Powiązania:
https://bibliotekanauki.pl/articles/89820.pdf
Data publikacji:
2011
Wydawca:
Centralny Instytut Ochrony Pracy
Tematy:
farmers
pesticide exposure
pesticide-related problems
geographic information system (GIS)
pesticide residue
Opis:
This study aimed to determine unsafe farming practices, nonergonomically designed equipment, and possible adverse health effects of pesticide exposure. Data were gathered with a structured survey, physical examination and blood extraction. Environmental monitoring was done for vegetables to determine multipesticide residue. Forty-eight percent of respondents reported feeling sick because of work. Vegetable residue was found in 16.67% of the samples. Vegetable profenofos of ~1 mg exceeded the necessary average daily intake of a maximum of 0.006 mg. Data also showed nonergonomically designed tools and unsafe work practices that increased pesticide exposure such as re-entering recently sprayed areas, a damaged backpack sprayer, spills during spraying, and no ventilation in greenhouses.
Źródło:
International Journal of Occupational Safety and Ergonomics; 2011, 17, 4; 445-453
1080-3548
Pojawia się w:
International Journal of Occupational Safety and Ergonomics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Late Tortonian bryozoans from Mut Basin, Central Anatolian Plateau, southern Turkey
Autorzy:
Zagorsek, K.
Gordon, D.P.
Powiązania:
https://bibliotekanauki.pl/articles/21300.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Late Tortonian
Tortonian
bryozoan
Mut Basin
Central Anatolian Plateau
Turkey [geogr.]
Bryozoa
Cheilostomata
Basyaylella
Ostrovskia
Eocene
Miocene
Opis:
Sixteen bryozoan species have been identified in the Başyayla section, Mut Basin, southern Turkey. Five of these species are described here, including two new to science representing new genera: Basyaylella elsae gen. et sp. nov. and Ostrovskia triforamina gen. et sp. nov. The other three described species (Exidmonea sp., Biflustra savartii, and Margaretta sp.) show unusual features that have not been reported previously. Based on bryozoan data, the Başyayla sequence represents a tropical to subtropical, normal marine environment, with seafloor composed of fine sedimentary particles in a low−energy setting.
Źródło:
Acta Palaeontologica Polonica; 2013, 58, 3
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Natural gas companies trends and perspectives in production, storage and consumption of natural gas
Nowe trendy przedsiębiorstw branży gazowniczej : perspektywy wydobycia, magazynowania oraz konsumpcji gazu ziemnego
Autorzy:
Stefanescu, D. P.
Petrescu, V.
Powiązania:
https://bibliotekanauki.pl/articles/300352.pdf
Data publikacji:
2009
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
gaz
ekonomia Rumunii
gas
Romanian economy
Opis:
The history of natural gas exploitation has an important role in the Romanian economical evolution. 100 years of gas activity represents a period when the event from the beginning of the last century, that of discovering the natural gas in Transylvania, subsequently changed in an important economical segment with a infrastructure of considerable dimensions.
Historia eksploatacji gazu ziemnego odgrywa ważną rolę w rozwoju ekonomicznym Rumuni. 100 lat aktywności branży gazowniczej prezentuje okres czasu mający swe korzenie w początkach ubiegłego wieku, kiedy to odkrycie złoża gazu ziemnego w Transylwanii zmieniło późniejszą ekonomię tego kraju oraz pozwoliło na zbudowanie infrastruktury o znacznych rozmiarach.
Źródło:
Wiertnictwo, Nafta, Gaz; 2009, 26, 1--2; 337-343
1507-0042
Pojawia się w:
Wiertnictwo, Nafta, Gaz
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Noninvasive stimulation opportunities in a marginal gas field
Autorzy:
Stefanescu, D. P.
Nitulete, A.
Powiązania:
https://bibliotekanauki.pl/articles/298874.pdf
Data publikacji:
2016
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
noninvasive simulation
Laslau Mare field
Transylvanian Basin
Opis:
The Laslau Mare field is a brown gas field in the Transylvanian Basin. The field was developed in the 1970s and the production consists of more than 99% methane gas and low WGR (average of 0.03 m3/kscm). Current reservoir pressures are at a less than a third of initial values. As in any mature field with increasing water production and reservoir pressure depletion, several degrees of formation damage and tubular obstructions have been observed. Mud invasion, plugged perforation, water blockage and scale precipitation at the near wellbore region are factors impairing wells to produce at potential. Adding to the above the fact, the reservoir is water sensitive (low reservoir pressures and water wet reservoir). Severe constraints on production were seen when performing any sort of operation requiring the use of water based fluids, as severe losses occur. These procedures have always given post-job challenges to production engineers. Skin induced by mud or liquid losses is highly affecting wells post job performance. Long recovery times have been observed following workovers’ operations in Laslau Mare (0.5 to 2.5 years recovery for workovers and one to three months for wash treatments). Perforation and re-perforation operations are one of the best way to overcome the formation damage, bypass the invaded zones and open new production zones. Historically, perforation was done with casing guns in overbalanced condition. This practice induces immediately a skin created by fluids losses and prolong the flow back periods making the stimulation much less effective. Another methodology is to run through tubing guns and perforate in underbalanced conditions with smaller guns being limited by the completion size. In the latter case, the perforation performance are much less than the casing gun ones. In both cases, the full potential of the well is not achieved. A newer methodology is introducing re-perforation/perforation with casing guns in underbalanced, dry conditions, within snubbing operations. The methodology allows instantaneous gain of production and maximizes well recovery factor in the long term. Two pilot operations were executed with very good results and promising opportunities arise for candidate wells in the field.
Źródło:
AGH Drilling, Oil, Gas; 2016, 33, 2; 507-514
2299-4157
2300-7052
Pojawia się w:
AGH Drilling, Oil, Gas
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A new approach of mature gas fields rehabilitation from Transylvanian Basin (Romania)
Autorzy:
Stefanescu, D.-P.
Vlasin, I.
Powiązania:
https://bibliotekanauki.pl/articles/299046.pdf
Data publikacji:
2013
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
mature gas fields rehabilitation
subsurface management of the reservoirs
incremental production
additional reserves
geological and physical model
Opis:
The mature gas fields rehabilitation represents a permanent concern of the Romgaz technical management, being considered one of the major priority of the development strategy of our company. The most part of our gas fields located in the geological unit of Transylvanian Basin are characterized by an advanced stage of exploitation, with a long production history and high cumulatives, having a current recovery factors of more than 60-70%. This status gives them the name "mature fields", or "brownfields" concepts logically associated with another notion, called "rehabilitation", also very frequently used in the world oil and gas industry. As the production decreasing became actually more obviously, due to the natural energetic decline of the reservoirs, the only viable solution to overcome this, consists in finding technical, commercial and operational best practices designed to develop incremental production and access additional reserves. This issue has preoccupied also the Romgaz technical team to implement and develop in the same time a new management strategy of this type of reservoirs, setting up a special department for designing the rehabilitation projects for our mature gas fields.
Źródło:
AGH Drilling, Oil, Gas; 2013, 30, 1; 199-207
2299-4157
2300-7052
Pojawia się w:
AGH Drilling, Oil, Gas
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On Unitary Analogue of \(f_g\)-perfect numbers and \(\Psi_s\)-perfect numbers
Autorzy:
Shukla, D.P.
Pandey, Shikha
Powiązania:
https://bibliotekanauki.pl/articles/744875.pdf
Data publikacji:
2011
Wydawca:
Polskie Towarzystwo Matematyczne
Tematy:
\(f_g\)-Perfect Numbers
unitary divisors
arithmetic functions
Dedekind’s function
g-perfect numbers
\(\Psi_s\)-perfect numbers
Opis:
In this paper unitary analogue of \(f_g\)-Perfect numbers and some properties of Dedekind’s function and all the \(\Psi_s\)-perfect numbers have been discussed.
Źródło:
Commentationes Mathematicae; 2011, 51, 2
0373-8299
Pojawia się w:
Commentationes Mathematicae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Identification of safety hazards in Indian underground coal mines
Autorzy:
Tripathy, D. P.
Ala, C. K.
Powiązania:
https://bibliotekanauki.pl/articles/92126.pdf
Data publikacji:
2018
Wydawca:
Główny Instytut Górnictwa
Tematy:
underground coal mining
hazard identification
risk assessment
safety control
accident analysis
górnictwo podziemne
identyfikacja zagrożenia
ocena ryzyka
kontrola bezpieczeństwa
analiza wypadków
Opis:
To improve safety the application of effective risk management has become a requirement in the mining industry. The effectiveness of mining risk management essentially depends on the risk assessment process, as the output of the risk assessment process helps the mine management to decide upon the control measures to be employed to mitigate the risks identified in the mine. The application of risk assessment in mines has become important not only for ensuring a safe working environment but, also, it is now a legal requirement. The capability of a risk assessment process depends on the hazard identification phase, as unidentified hazards may lead to unknown and unmanageable risks. Therefore, it is essential to identify all the potential hazards to manage the risks in mines. The object of this study is to identify the safety hazards present in Indian underground coal mines and to build a preliminary database of the identified hazards. Accident data collected from the Directorate General of Mines Safety in India and a public sector coal mining company was studied to identify safety hazards that may probably lead to accidents. The database could help the mine management to improve decision making after analysing and evaluating the safety risks of identified hazards.
Źródło:
Journal of Sustainable Mining; 2018, 17, 4; 175-183
2300-1364
2300-3960
Pojawia się w:
Journal of Sustainable Mining
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fourth order nonlinear evolution equation for interfacial gravity waves in the presence of air flowing over water and a basic current shear
Autorzy:
Majumder, D. P.
Dhar, A. K.
Powiązania:
https://bibliotekanauki.pl/articles/265668.pdf
Data publikacji:
2015
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
nonlinear evolution equation
basic current shear
Stokes gravity wave
równania nieliniowe
przepływy Stokes'a
grawitacja
Opis:
A fourth order nonlinear evolution equation, which is a good starting point for the study of nonlinear water waves as first pointed out by Dysthe (1979) is derived for gravity waves propagating at the interface of two superposed fluids of infinite depth in the presence of air flowing over water and a basic current shear. A stability analysis is then made for a uniform Stokes gravity wave train. Graphs are plotted for the maximum growth rate of instability and for wave number at marginal stability against wave steepness for different values of air flow velocity and basic current shears. Significant deviations are noticed from the results obtained from the third order evolution equation, which is the nonlinear Schrödinger equation.
Źródło:
International Journal of Applied Mechanics and Engineering; 2015, 20, 3; 517-530
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Automated code generation for safety-related applications: a case study
Automatyczna generacja programów dla komputerowych systemów bezpieczeństwa: przykład studialny
Autorzy:
Gluch, D. P.
Kornecki, A. J.
Powiązania:
https://bibliotekanauki.pl/articles/305421.pdf
Data publikacji:
2007
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
inżynieria oprogramowania
narzędzia oprogramowania
automatyczna generacja kodu
software engineering process
software tools
automatic code generation
Opis:
Artykuł opisuje możliwości zastosowań technologii automatycznej generacji programów (AGP) dla komputerowych systemów bezpieczeństwa. Przeprowadzone badania koncentrowały się na charakterystykach systemów oprogramowania bazujących na modelowaniu i automatycznych narzędziach oprogramowania. W szczególności studium pozwoliło na kolekcję danych dotyczących wymagań inżynieryjnych, wiedzy i wysiłku koniecznego do pomyślnej realizacji projektu wykorzystującego praktykę i technologię AGP. Takie charakterystyki, jak organizacja generowanego programu, rozmiar, łatwość czytania, relacja między programem a modelem, konstrukcje programu ułatwiające operacje w czasie rzeczywistym i generacja przerwań, były przedmiotem identyfikacji. Dodatkowo, projekt używał metodologii inżynierii oprogramowania, gdzie analiza i konstrukcja były zintegrowane w procesie realizacji programu na bazie modelu. Analiza dotyczyła statycznych i dynamicznych charakterystyk wybranych technik i narzędzi oprogramowania wpływających na bezpieczeństwo systemu.
Źródło:
Computer Science; 2007, 8, Spec. Ed; 37-48
1508-2806
2300-7036
Pojawia się w:
Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
CFD simulations for selection of appropriate blade profile for improving energy efficiency in axial flow mine ventilation fans
Autorzy:
Panigrahi, D. C.
Mishra, D. P.
Powiązania:
https://bibliotekanauki.pl/articles/91904.pdf
Data publikacji:
2014
Wydawca:
Główny Instytut Górnictwa
Tematy:
mine ventilation
axial flow fan
energy efficiency
lift
CFD
drag
wentylacja kopalń
wentylator osiowy
efektywność energetyczna
winda
Opis:
Purpose This study focuses on one of the key design aspects of mine ventilation fans, i.e. the selection of an appropriate aerofoil blade profile for the fan blades in order to enhance the energy efficiency of axial flow mine ventilation fans, using CFD simulations. Methods Computational simulations were performed on six selected typical aerofoil sections using CFD code ANSYS Fluent 6.3.26 at angles of attack varying from 0 to 21 at an interval of 3 and at Reynolds number Re = 3 × 106, and various aerody-namic parameters, viz. coefficients of lift (Cl) and drag (Cd) as a function of angle of attack (α) were determined to assess the efficiency of the aerofoils. Results The study revealed that the angle of attack has a significant effect on the lift and drag coefficients and stall condition oc-curred at α values of 12 and 15 in most of the aerofoils. Based on the criterion of higher lift to drag ratio (Cl/Cd), a blade profile was chosen as the most efficient one for mine ventilation fans. Practical implications This study forms a basis for selecting appropriate blade profiles for the axial flow fans used for ventilation in mining industry. Originality/ value The application of an appropriate aerofoil blade profile will impart energy efficiency to the mine ventilation fans and thereby result in energy saving in mine ventilation.
Źródło:
Journal of Sustainable Mining; 2014, 13, 1; 15-21
2300-1364
2300-3960
Pojawia się w:
Journal of Sustainable Mining
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Age, growth rate, and otolith growth of polar cod (Boreogadus saida) in two fjords of Svalbard, Kongsfjorden and Rijpfjorden
Autorzy:
Fey, D.P.
Weslawski, J.M.
Powiązania:
https://bibliotekanauki.pl/articles/49041.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
polar cod
Boreogadus saida
age
growth rate
annual ring
fish size
Svalbard Fjord
Kongsfjorden area
Opis:
This work presents biological information for polar cod (Boreogadus saida) collected with a Campelen 1800 shrimp bottom trawl in Kongsfjorden (two stations located in the inner part of the fjord adjacent to the glacier) and Rijpfjorden (one station at the entrance to the fjord) in September and October 2013. The otolith-based ages of polar cod collected in Kongsfjorden (6.1–24 cm total length TL; n = 813) ranged from 0 to 4 years. The growth rate was relatively constant at approximately 4.7 cm year−1 between years 1 and 4, which indicates that growth was fast in the glacier area. The ages of polar cod collected in Rijpfjorden (8.6–15.9 cm TL; n = 64) ranged from 2 to 3 years. The fish from Rijpfjorden were smaller at age than those from Kongsfjorden, and their growth rate between years 2 and 3 (no other age classes were available) was approximately 3.3 cm year−1. In both fjords, males and females were of the same size-at-age and the same weight-at-TL. The small sampling area means that the results on growth rate are not representative of the entire fjords. Instead, the results can be discussed as presenting the possible growth rates of some populations. A strong relationship was identified between otolith size (length and weight) and fish size (TL and TW), with no differences between males and females or the fjords. A significant, strong relationship was also noted between fish and otolith growth rates.
Źródło:
Oceanologia; 2017, 59, 4
0078-3234
Pojawia się w:
Oceanologia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The effect of randomness on the stability of capillary gravity waves in the presence of air flowing over water
Autorzy:
Majumder, D. P.
Dhar, A. K.
Powiązania:
https://bibliotekanauki.pl/articles/265777.pdf
Data publikacji:
2015
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
capillary gravity waves
randomness
evolution equation
instability
fala grawitacyjna
przypadkowość
niestabilność
Opis:
A nonlinear spectral transport equation for the narrow band Gaussian random surface wave trains is derived from a fourth order nonlinear evolution equation, which is a good starting point for the study of nonlinear water waves. The effect of randomness on the stability of deep water capillary gravity waves in the presence of air flowing over water is investigated. The stability is then considered for an initial homogenous wave spectrum having a simple normal form to small oblique long wave length perturbations for a range of spectral widths. An expression for the growth rate of instability is obtained; in which a higher order contribution comes from the fourth order term in the evolution equation, which is responsible for wave induced mean flow. This higher order contribution produces a decrease in the growth rate. The growth rate of instability is found to decrease with the increase of spectral width and the instability disappears if the spectral width increases beyond a certain critical value, which is not influenced by the fourth order term in the evolution equation.
Źródło:
International Journal of Applied Mechanics and Engineering; 2015, 20, 4; 835-855
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-25 z 2968

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