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Wyświetlanie 1-7 z 7
Tytuł:
Double Diffusion in $Ar-N_2$ Binary Gas System at the Constant Value of Temperature Gradient
Autorzy:
Seleznev, V.
Kosov, V.
Poyarkov, I.
Fedorenko, O.
Beketaeva, M.
Powiązania:
https://bibliotekanauki.pl/articles/1400287.pdf
Data publikacji:
2013-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
51.10.+y
42.25.+f
Opis:
An experimental study of the "diffusion-gravitational convection" transition boundary in an $Ar-N_2$ binary system at different pressures and a constant temperature gradient is performed. It is shown that the diffusion is replaced by the gravitational convection at a pressure p ≈ 0.5 MPa. In terms of the stability theory, a perturbation boundary line is determined, dividing the Rayleigh numbers plane into the regions of the diffusion and the convective mass transfer. The experimental data agree well with the theoretical values.
Źródło:
Acta Physica Polonica A; 2013, 123, 1; 62-66
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Liquefied natural gas storage of variable composition
Magazynowanie skroplonego gazu ziemnego o zmiennym składzie
Autorzy:
Łaciak, M.
Powiązania:
https://bibliotekanauki.pl/articles/218812.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
LNG
liquefied natural gas
regasification
energy efficiency
liquefied gas storing
LNG stratification
double diffusion
dostawy LNG
gaz LNG
regazyfikacja
podwójna dyfuzja
Opis:
Thanks to the increasing diversification of LNG supply sources, being a result of the growing number of LNG liquefaction installations over the World, increase of short-term trade contracts and general trend to globally liberalize gas markets, reception terminals have to cope with the broad range of qualitatively diversified LNG deliveries from various sources. Different LNG deliveries potentially have different density caused by different gas composition. Although the LNG composition depends on LNG source, it mainly consists of methane, ethane, propane, butane and trace nitrogen. When a new supply of LNG is transported to the tank, the LNG composition and temperature in the tank can be different from LNG as delivered. This may lead to the liquid stratification in the tank, and consequently the rollover. As a result, LNG rapidly evaporates and the pressure in the tank increases. More and more restrictive safety regulations require fuller understanding of the formation and evolution of layers. The paper is focused on the analysis of liquid stratification in the tank which may take place when storing LNG, and which process leads to the rapid evaporation of considerable quantities of LNG. The aim was to attempt modeling of the process of liquid stratification in an LNG tank. The paper is closed with the results of modelling.
Dzięki rosnącej dywersyfikacji źródeł dostaw LNG, spowodowanej zwiększającą się liczbą instalacji skraplania gazu na całym świecie, wzrostem ilości kontraktów krótkoterminowych w handlu i ogólnej tendencji do globalnej liberalizacja rynków gazu, terminale do odbioru muszą radzić sobie z coraz większą gamą różnych jakościowo dostaw LNG z różnych źródeł. Różne dostawy LNG mają potencjalnie inną gęstość dzięki różnym składom gazu. Chociaż kompozycja LNG zależy od źródła, to przede wszystkim składa się z metanu, etanu, propanu, butanu i w śladowych ilościach z azotu. Gdy nowa dostawa LNG jest doprowadzana do zbiornika, skład i temperatura LNG już w zbiorniku może być inny niż dostarczanego. Może to prowadzić do rozwarstwienia cieczy w zbiorniku, a w konsekwencji wystąpienia zjawiska znanego jako „rollover”. W wyniku tego zjawiska następuje gwałtowne odparowanie LNG i nagły wzrost ciśnienia w zbiorniku. Coraz bardziej restrykcyjne przepisy dotyczące bezpieczeństwa wymagają pełniejszego zrozumienia zjawiska tworzenia i ewolucji warstw. W artykule przeprowadzono analizę procesu rozwarstwienia cieczy w zbiorniku, mogącego wystąpić podczas magazynowania skroplonego gazu ziemnego, a prowadzącego do gwałtownego odparowania znacznych ilości LNG. Celem była próba modelowania procesu powstawania rozwarstwienia się cieczy w zbiorniku LNG. Przedstawione zostały wyniki modelowania tego zjawiska.
Źródło:
Archives of Mining Sciences; 2015, 60, 1; 225-238
0860-7001
Pojawia się w:
Archives of Mining Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Screening for ESβL producing E. coli isolated from clinical urine samples collected from different places of Kalaburagi city
Autorzy:
Ramachar, Raghavendra
Gaddad, Subhashchandra M.
Shivannavar, Channappa T.
Powiązania:
https://bibliotekanauki.pl/articles/1177430.pdf
Data publikacji:
2018
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Antibiogram
Double-disc diffusion test
ESβL
Green Metallic Sheen
Phenotypic detection
Uropathogenic E. coli
Opis:
Bacteria are capable of invading and infecting humans, leading to disease and sometimes death. Different body tissues, organs and systems are vulnerable to different organisms. This study was aimed to isolate and identify the bacteria causing Urinary Tract Infection (UTI) in different age groups and also screened for ESβL production. The mid-stream urine samples showing symptoms of urinary tract infections were collected in a wide container from different hospitals and diagnostic centres of Kalaburagi city. The isolation of uropathogen was done by semi-quantitative method of inoculating the samples on the selective and differential media such as Eosin Methylene Blue (EMB) and MacConkey (MAC) agar media respectively. The isolated pathogen was identified by conventional methods like cultural, morphological and biochemical tests. The antibiotic susceptibility test was carried out by Kirby-Bauer disc diffusion technique and ESβL production by double disk-diffusion test (DDDT) as per CLSI guidelines (2013). Out of 550 samples screened, a total of 288 bacteria were isolated of those half of them (146) were E. coli isolates and all were found to be multidrug resistant and half of them (50%) were of ESβL producers. All ESβL producing E. coli isolates were resistant to ceftazidime and exhibited higher level of resistance to Cephalothin, Erythromycin, Cotrimoxazole and Aztreonam. As ESβL producing organisms limits the available treatment options, so, the timely administration of sensitive antibiotic and avoiding antibiotic abuse will help in curing the disease without going for the costly drugs such as Carbapenems. Our study revealed that nitrofurantoin, ofloxacin and cefoxitin may be considered as drug of choice for the treatment of UTI patients. The ESβL production in uropathogens should be continuously monitored in the clinics and hospitals as to avoid the emergence of more multi drug resistance strains.
Źródło:
World Scientific News; 2018, 103; 107-118
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bayesian DEJD Model and Detection of Asymmetry in Jump Sizes
Autorzy:
Kostrzewski, Maciej
Powiązania:
https://bibliotekanauki.pl/articles/2076552.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
double exponential jump diffusion model
Kou model
Bernoulli jump-diffusion model
MCMC methods
latent variables
Opis:
News might trigger jump arrivals in financial time series. The "bad" news and "good" news seem to have distinct impact. In the research, a double exponential jump distribution is applied to model downward and upward jumps. Bayesian double exponential jump-diffusion model is proposed. Theorems stated in the paper enable estimation of the model’s parameters, detection of jumps and analysis of jump frequency. The methodology, founded upon the idea of latent variables, is illustrated with simulated data.
Źródło:
Central European Journal of Economic Modelling and Econometrics; 2015, 1; 43-70
2080-0886
2080-119X
Pojawia się w:
Central European Journal of Economic Modelling and Econometrics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Voltage Dependence of Supercapacitor Capacitance
Autorzy:
Szewczyk, A.
Sikula, J.
Sedlakova, V.
Majzner, J.
Sedlak, P.
Kuparowitz, T.
Powiązania:
https://bibliotekanauki.pl/articles/221295.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Electronic Double-Layer Capacitor (EDLC)
charge diffusion
recovery voltage
Opis:
Electronic Double-Layer Capacitors (EDLC), called Supercapacitors (SC), are electronic devices that are capable to store a relatively high amount of energy in a small volume comparing to other types of capacitors. They are composed of an activated carbon layer and electrolyte solution. The charge is stored on electrodes, forming the Helmholtz layer, and in electrolyte. The capacitance of supercapacitor is voltage- dependent. We propose an experimental method, based on monitoring of charging and discharging a supercapacitor, which enables to evaluate the charge in an SC structure as well as the Capacitance-Voltage (C-V) dependence. The measurement setup, method and experimental results of charging/discharging commercially available supercapacitors in various voltage and current conditions are presented. The total charge stored in an SC structure is proportional to the square of voltage at SC electrodes while the charge on electrodes increases linearly with the voltage on SC electrodes. The Helmholtz capacitance increases linearly with the voltage bias while a sublinear increase of total capacitance was found. The voltage on SC increases after the discharge of electrodes due to diffusion of charges from the electrolyte to the electrodes. We have found that the recovery voltage value is linearly proportional to the initial bias voltage value.
Źródło:
Metrology and Measurement Systems; 2016, 23, 3; 403-411
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Bayesian Methods of Jump Detection: The Example of Gas and EUA Contract Prices
Autorzy:
Kostrzewski, Maciej
Powiązania:
https://bibliotekanauki.pl/articles/2076144.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
jump
jump-diffusion model
stochastic volatility
double exponential distribution
commodity markets
Nauki Humanistyczne i Społeczne
Opis:
In the paper we present and apply a Bayesian jump-diffusion model and stochastic volatility models with jumps. The problem of how to classify an observation as a result of a jump is addressed, under the Bayesian approach, by introducing latent variables. The empirical study is focused on the time series of gas forward contract prices and EUA futures prices. We analyse the frequency of jumps and relate the moments in which jumps occur to calendar effects or political and economic events and decisions. The calendar effects explain many jumps in gas contract prices. The single jump is identified in the EUA futures prices under the SV-type models. The jump is detected on the day the European Parliament voted against the European Commission’s proposal of backloading. The Bayesian results are compared with the outcomes of selected non-Bayesian techniques used for detecting jumps.
Źródło:
Central European Journal of Economic Modelling and Econometrics; 2019, 2; 107-131
2080-0886
2080-119X
Pojawia się w:
Central European Journal of Economic Modelling and Econometrics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Double-image encryption scheme based on the phase-truncated multiple-parameter Fresnel transform
Autorzy:
Zhou, Ling
Zhou, Hang
Ma, Yan
Zhou, Nan-Run
Powiązania:
https://bibliotekanauki.pl/articles/2086756.pdf
Data publikacji:
2022
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
chaotic system
phase-truncated multiple-parameter Fresnel transform
scrambling
diffusion
image encryption
Opis:
A double-image encryption algorithm is proposed with the phase-truncated multiple-parameter Fresnel transform. Firstly, the pixel positions of two plaintext images are scrambled and then the results are merged into one image with the scrambling operation. Subsequently, the resulting image is encrypted by phase truncation and phase reservation in the multiple-parameter Fresnel transform domain. The phase information is scrambled by the affine transform and then recombined with the amplitude information. The final encryption image is obtained with the pixel scrambling and diffusion methods to further enhance the security of the image encryption system, where the scrambling and diffusion operations are based on logistic map, logistic-sine system and 2D logistic-adjusted-sine map. The image encryption scheme is robust against the common attacks due to the nonlinear properties of diffusion and phase truncation. Numerical simulation results verify the performance and the security of the proposed double-image algorithm based on the phase-truncated multiple-parameter Fresnel transform.
Źródło:
Optica Applicata; 2022, 52, 2; 163--177
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-7 z 7

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