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Tytuł:
Dynamic modeling of the isoamyl acetate reactive distillation process
Autorzy:
Ali, S. S.
Hossain, SK. S.
Asif, M.
Powiązania:
https://bibliotekanauki.pl/articles/778351.pdf
Data publikacji:
2017
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
reactive distillation
process simulator
isoamyl acetate
dynamic modeling
disturbance
Opis:
The cost-effectiveness of reactive distillation (RD) processes makes them highly attractive for industrial applications. However, their preliminary design and subsequent scale-up and operation are challenging. Specifically, the response of RD system during fluctuations in process parameters is of paramount importance to ensure the stability of the whole process. As a result of carrying out simulations using Aspen Plus, it is shown that the RD process for isoamyl acetate production was much more economical than conventional reactor distillation configuration under optimized process conditions due to lower utilities consumption, higher conversion and smaller sizes of condenser and reboiler. Rigorous dynamic modeling of RD system was performed to evaluate its sensitivity to disturbances in critical process parameters; the product flow was quite sensitive to disturbances. Even more sensitive was product composition when the disturbance in heat duties of condenser or reboiler led to a temperature decrease. However, positive disturbance in alcohol feed is of particular concern, which clearly made the system unstable.
Źródło:
Polish Journal of Chemical Technology; 2017, 19, 1; 59-66
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ethnobotanical knowledge and folk medicinal significance of the flora of district Gujrat, Punjab, Pakistan
Autorzy:
Ali, S.S.
Hussain, K.
Nawaz, K.
Bhatti, K.H.
Bashir, Z.
Nazeer, A.
Arif, U.
Jafar, S.
Siddiqi, E.H.
Powiązania:
https://bibliotekanauki.pl/articles/2049056.pdf
Data publikacji:
2020
Wydawca:
Instytut Włókien Naturalnych i Roślin Zielarskich
Tematy:
District Gujrat
medicine
ethnomedicinal flora
survey
native people
prowincja Gujrat
lek
rośliny lecznicze używane w medycynie ludowej
rdzenni mieszkańcy
badanie ankietowe
Opis:
Introduction: Medicinal plants are the natural source of medicines used in treatment of many diseases among local communities of various countries. It is also the raw material for the pharmaceutical industry. Pakistan is a country with a variety of medicinal plants, comprehensively studied in some areas, while others still need more studies of their flora. Objectives: The study was performed to catalogue the flora of district Gujrat, Punjab, Pakistan and to assess its ethnomedicinal importance. Methods: A field survey was conducted in the Gujrat district (including Sarai Alamgir, Gujrat and Kharian) in 2019–2020 to collect the flora. Nearly 200 people of various age groups were interviewed and the questionnaire was filled, the gender and professions of the participants were also noted. Results: The plant species collected belonged to 32 different Angiosperm families i.e. Poaceae, Brassicaceae, Fabaceae, Asteraceae, Moraceae, Amaranthaceae, Apiaceae, Myrtaceae, Rutaceae, Solanaceae, Malvaceae, Euphorbiaceae and Lamiaceae. The obtained material consisted of 30 herbs, 20 shrubs and 22 trees. The floral parts used most often were leaves (63%) followed by: flower (41%), fruit (28%), stem (16%), seed (16%), bark (14%), root (13%), whole plant (12%), underground part (3%) and latex (3%). According to the study, the highest RFC (Relative Frequency of Citation) values were 0.1 in Cassia fistula L. (0.25) and the smallest RFC values were observed in Stellaria media (L.) Vill. – 0.025. The highest UV (Use Values) were noted for Achyranthes aspera L. at 0.9. In disease category, the highest value (0.67) of ICF (Informant Consensus Factor) was observed for stomach and skin infections, while the lowest ICF value was noted for diabetes and gonorrhoea (0.27). Conclusions: It was concluded that the Gujrat district is rich in useful plants that can be used in the preparation of various medicines as well as be sold on the herbal market.
Źródło:
Herba Polonica; 2020, 66, 1; 37-51
0018-0599
Pojawia się w:
Herba Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ethnobotanical investigation of significant seasonal medicinal weeds of Toba Tek Singh District, Punjab, Pakistan
Autorzy:
Tufail, M.
Hussain, K.
Nawaz, K.
Iqbal, I.
Arshad, N.
Shahzadi, A.
Javed, A.
Nazeer, A.
Bashir, Z.
Qurban, M.
Zeb, J.
Ali, S.S.
Powiązania:
https://bibliotekanauki.pl/articles/2049359.pdf
Data publikacji:
2021
Wydawca:
Instytut Włókien Naturalnych i Roślin Zielarskich
Tematy:
weeds
ethnobotany
flora
survey
chwasty
etnobotanika
badanie
Opis:
Introduction: Medicinal plants are found throughout the world but most are considered weeds. They are – directly or indirectly – the major source of medicines in pharmaceutical and herbal industries. Formulations used to prepare medicines or the method of use for these plants are mainly based on folk or traditional knowledge. This folk knowledge is not documented in many areas and needs to be explored. Objectives: This study was aimed to enlist the seasonal weed species with traditional medicinal usage in Toba Tek Singh District, Punjab, Pakistan. Methods: Field surveys were arranged in winter and summer 2019–2020 to enlist the important medicinal weeds and traditional knowledge of the local community. Data collected were as follows: local name of weed, medicinal use, method and part used. Results: Numerous wild perennial, biennial and annual plants were identified, 30 of them were ethnomedicinally important in the local community. They were grouped in 16 families. It was found that whole weed is used in many prescriptions (37%). Achyranthes aspera L. (Amaranthaceae) was the most common weed used in treating fevers, respiratory problems and asthma. Cichorium intybus L. (Asteraceae) was used in summer drinks to reduce thirst, improve digestion and liver function. Chenopodium album L. (Amaranthaceae) was used with 0.71 UV and 0.147 RFC values. Medicago polymorpha L. (Fabaceae) was used to treat kidney, intestinal and bladder infections. Its UV was 0.65 and RFC was 0.121. Tribulus terrestris L. (Zygophyllaceae) was used in impotency treatment, and in the removal of kidney stones and urinary tract infections treatment. It has 0.63 UV and 0.21 RFC values. This weed also showed the highest Fidelity Level (FL) (77%), as compared to other weeds. Conclusion: It was concluded that there are many significant medicinal weeds in the Toba Tek Singh District, Punjab, Pakistan that are used in traditional medicines in treating various disorders. These plants also showed herbal or pharmacological importance that can be used to develop medicine at commercial scale.
Źródło:
Herba Polonica; 2021, 67, 2; 29-38
0018-0599
Pojawia się w:
Herba Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
De la Vallée Poussin Summability, the Combinatorial Sum $\sum_{k=n}^{2n-1}$ (2k/k) and the de la Vallée Poussin Means Expansion
Autorzy:
Ali, Z. S.
Powiązania:
https://bibliotekanauki.pl/articles/357696.pdf
Data publikacji:
2017
Wydawca:
Politechnika Rzeszowska im. Ignacego Łukasiewicza. Oficyna Wydawnicza
Tematy:
complete metric space
hyperbolic space
infinite product
nonexpansive mapping
random weak ergodic property
przestrzeń metryczna całkowita
przestrzeń hiperboliczna
produkt nieskończony
mapowanie
własności ergodyczne
Opis:
In this paper we apply the de la Vallee Poussin sum to a combinatorial Chebyshev sum by Ziad S. Ali in [1]. One outcome of this consideration is the main lemma proving the following combinatorial identity: with $Re(z)$ standing for the real part of z we have \[ \sum_{k=n}^{2n-1}\left({2k \atop k}\right) = Re\left(\left({2k \atop k}\right) \text{}_{2}F_{1}(1, 1/2 + n; 1 + n; 4\right) - \left({4n \atop 2n}\right) \text{}_{2}F_{1}(1, 1/2 + 2n; 1 + 2n; 4) \] Our main lemma will indicate in its proof that the hypergeometric factors \[ _{2}F_{1}(1, 1/2 + n; 1 + n; 4); \text{ and } _{2}F_{1}(1, 1/2 + 2n; 1 + 2n; 4) \] are complex, each having a real and imaginary part. As we apply the de la Vallee Poussin sum to the combinatorial Chebyshev sum generated in the Key lemma by Ziad S. Ali in [1], we see in the proof of the main lemma the extreme importance of the use of the main properties of the gamma function. This represents a second important consideration. A third new outcome are two interesting identities of the hypergeometric type with their new Meijer G function analogues. A fourth outcome is that by the use of the Cauchy integral formula for the derivatives we are able to give a dierent meaning to the sum: \[ \sum_{k=n}^{2n-1}\left({2k \atop k}\right) \] A fifth outcome is that by the use of the Gauss-Kummer formula we are able to make better sense of the expressions \[ \left({2n \atop n}\right)\text{}_{2}F_{1}(1, 1/2 + n; 1 + n; 4), \text{ and } \left({4n \atop 2n}\right)\text{}_{2}F_{1}(1, 1/2 + 2n; 1 + 2n; 4) \] by making use of the series denition of the hypergeometric function. As we continue we notice a new close relation of the Key lemma, and the de la Vallee Poussin means. With this close relation we were able to talk about P the de la Vallee Poussin summability of the two innite series $\sum_{n=0}^{\infty}\cos n\theta$ and $\sum_{n=0}^{\infty}(-1)^{n}\cos n\theta$. Furthermore the application of the de la Vallee Poussin sum to the Key lemma has created two new expansions representing the following functions: \[ \frac{2^{(n-1)}(1+x)^{n}(-1+2^{n}(1+x)^{n})}{n(2x+1)}, \text{ where } x=\cos \theta \] and \[ \frac {-2^{(n-1)}(-1 + 2^{n}(1-x)^{n})(1-x)^{n}} {n(2x - 1)}, \text{ where } x=\cos \theta \] in terms of the de la Vall´ee Poussin means of the two infinite series \[ \sum_{n=0}^{\infty}\cos\theta, \] and \[ \sum_{n=0}^{\infty}(-1)^{n}\cos\theta, \]
Źródło:
Journal of Mathematics and Applications; 2017, 40; 5-20
1733-6775
2300-9926
Pojawia się w:
Journal of Mathematics and Applications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structural and optical properties of nanostructured bismuth oxide
Autorzy:
Ali, R. S.
Powiązania:
https://bibliotekanauki.pl/articles/412556.pdf
Data publikacji:
2014
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
thin films’ bismuth oxide
optical properties
structural properties
Opis:
Thin films of bismuth oxide have been prepared utilizing vacuum evaporation. XRD anyalysis reveal that all the films were tetragonal polycrystalline structure with a preferred orientation along (002) plane. SEM images indicate that the grain size fall in the category of nanosize. AFM results assure that the nanonstructure behavior of thin films. Optical studies show that these films have a direct transition with optical energy gap equal to 2.5 eV.
Źródło:
International Letters of Chemistry, Physics and Astronomy; 2014, 15; 64-72
2299-3843
Pojawia się w:
International Letters of Chemistry, Physics and Astronomy
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The natural refuge policy for Bt cotton (Gossypium L.) in Pakistan - a situation analysis
Polityka dotycząca naturalnych ostoi w odniesieniu do upraw bawełny Bt (Gossypium L.) w Pakistanie - analiza sytuacji
Autorzy:
Ali, M.S.
Powiązania:
https://bibliotekanauki.pl/articles/28255.pdf
Data publikacji:
2013
Wydawca:
Polskie Towarzystwo Botaniczne
Opis:
Bt cotton (event Cry1Ac) was formally commercialized in Pakistan in 2010. However, there has been an increasing trend of planting unauthorized Bt cotton germplasm in farmers’ fields since 2003 with a high rate of adoption in the core cotton areas especially in the province Punjab. The transgenic cotton technology has provided the growers with substantial economic benefits and has reduced their dependence on pesticides for pest control, especially against Helicoverpa armigera (Hubner). However, keeping in view the capacity of this insect to develop resistance against novel chemical formulations, it is easily speculated that Bt toxin, too, is no exception. Refuge crop policy for mono transgenic crop events has helped in delaying the rate of resistance evolution in the target pests. Thus, in Pakistan, where planting of structured refuge crops along Bt cotton fields is not mandatory, the effectiveness and durability of Bt cotton technology may decrease due to a number of factors which are discussed in this review.
Bawełna Bt (toksyna Cry1Ac) została oficjalnie wprowadzona na rynek w Pakistanie w 2010 roku. Jednak od 2003 roku istnieje tendencja wśród rolników do sadzenia na polach bawełny Bt z niedopuszczonym materiałem genetycznym, a wskaźnik rolników przechodzących na uprawę tego rodzaju bawełny jest wysoki, w szczególności w prowincji Pendżab. Stosowanie technologii uprawy transgenicznych odmian bawełny przyniosło producentom bawełny znaczne korzyści ekonomiczne oraz zmniejszyło ich zależność od pestycydów zwalczających szkodniki, w szczególności Helicoverpa armigera (Hubner). Jednak mając na względzie, że ten owad posiada zdolność rozwijania odporności na nowe preparaty chemiczne, łatwo można wysnuć wniosek, że toksyna Bt również nie stanowi wyjątku. Polityka dotycząca prowadzenia upraw stanowiących ostoje w przypadku stosowania monokulturowych upraw transgenicznych odmian bawełny pomogła opóźnić szybkość wytworzenia odporności w badanych szkodnikach. Z tego powodu w Pakistanie, gdzie nie ma obowiązku prowadzenia obok pól z bawełną Bt upraw o odpowiedniej strukturze stanowiących ostoję, efektywność i trwałość technologii uprawy bawełny Bt mogą się zmniejszyć z powodu szeregu czynników, które omówione są w niniejszym artykule.
Źródło:
Acta Agrobotanica; 2013, 66, 2
0065-0951
2300-357X
Pojawia się w:
Acta Agrobotanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Deforestation and its impacts on climate change an overview of Pakistan
Autorzy:
Ali, A.
Riaz, S.
Iqbal, S.
Powiązania:
https://bibliotekanauki.pl/articles/11968.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
climate change
deforestation
Pakistan
catastrophic event
forest age
natural factor
weather
industrialization
urbanization
global temperature
surface temperature
disaster
South Asia
Opis:
Forests are one the main natural factors that regulate and determine climate, weather patterns and amount of CO2 of an area. With rapid industrialization and rapid urbanization there is a significant increase in deforestation and as a consequence rise in global mean surface temperatures. Rapid and unchecked cut down of forest cover has resulted in some of the worst disasters during the last decades. This paper focuses on studying the role of deforestation, its influence on climate change phenomena and its consequences in Pakistan.
Źródło:
Papers on Global Change; 2014, 21
2300-8121
1730-802X
Pojawia się w:
Papers on Global Change
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Molecular investigation and phylogeny of Theileria spp. from naturally infected sheep and the first report of Theileria sp. OT3 in Sulaymaniyah governorate/Iraq
Autorzy:
Abdullah, S.H.
Ali, S.A.
Powiązania:
https://bibliotekanauki.pl/articles/2087179.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Theileria ovis
T. lestoquardi
T. uilenbergi
PCR
sheep parasites
Źródło:
Polish Journal of Veterinary Sciences; 2021, 24, 2; 201-209
1505-1773
Pojawia się w:
Polish Journal of Veterinary Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Matlab Implementation of Differential GPS for Low-cost GPS Receivers
Autorzy:
Ali, Q
Montenegro, S.
Powiązania:
https://bibliotekanauki.pl/articles/116127.pdf
Data publikacji:
2014
Wydawca:
Uniwersytet Morski w Gdyni. Wydział Nawigacyjny
Tematy:
marine navigation
Global Positioning System GPS
Matlab, Differential GPS (DGPS)
GPS Receiver
unmanned aerial vehicle (UAV)
Global Navigation Satellite System (GNSS)
RINEX Format
Opis:
A number of public codes exist for GPS positioning and baseline determination in off-line mode. However, no software code exists for DGPS exploiting correction factors at base stations, without relying on double difference information. In order to accomplish it, a methodology is introduced in MATLAB environment for DGPS using C/A pseudoranges on single frequency L1 only to make it feasible for low-cost GPS receivers. Our base station is at accurately surveyed reference point. Pseudoranges and geometric ranges are compared at base station to compute the correction factors. These correction factors are then handed over to rover for all valid satellites observed during an epoch. The rover takes it into account for its own true position determination for corresponding epoch. In order to validate the proposed algorithm, our rover is also placed at a pre-determined location. The proposed code is an appropriate and simple to use tool for post-processing of GPS raw data for accurate position determination of a rover e.g. Unmanned Aerial Vehicle during post-mission analysis.
Źródło:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation; 2014, 8, 3; 343-350
2083-6473
2083-6481
Pojawia się w:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparative growth kinetic study of Newcastle disease virus, infectious bursal disease virus and avian influenza virus in chicken embryo fibroblast and DF-1 cell lines
Autorzy:
Anam, S.
Rahman, S.U.
Ali, S.
Saeed, M.
Goyal, S.M.
Powiązania:
https://bibliotekanauki.pl/articles/2087170.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
cytopathic effect
titer
growth kinetic
vaccine production
Źródło:
Polish Journal of Veterinary Sciences; 2021, 24, 2; 287-292
1505-1773
Pojawia się w:
Polish Journal of Veterinary Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Classification of EEG Signals Using Adaptive Time-Frequency Distributions
Autorzy:
Khan, N. A.
Ali, S.
Powiązania:
https://bibliotekanauki.pl/articles/221878.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Adaptive Directional Time-Frequency Distribution
EEG signals
Time-Frequency features
pattern recognition
Opis:
Time-Frequency (t-f) distributions are frequently employed for analysis of new-born EEG signals because of their non-stationary characteristics. Most of the existing time-frequency distributions fail to concentrate energy for a multicomponent signal having multiple directions of energy distribution in the t-f domain. In order to analyse such signals, we propose an Adaptive Directional Time-Frequency Distribution (ADTFD). The ADTFD outperforms other adaptive kernel and fixed kernel TFDs in terms of its ability to achieve high resolution for EEG seizure signals. It is also shown that the ADTFD can be used to define new time-frequency features that can lead to better classification of EEG signals, e.g. the use of the ADTFD leads to 97.5% total accuracy, which is by 2% more than the results achieved by the other methods.
Źródło:
Metrology and Measurement Systems; 2016, 23, 2; 251-260
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Leaching of manganese ores using corncob as reductant in H2SO4 solution
Autorzy:
Ali, S.
Iqbal, Y.
Farooq, U.
Ahmad, S.
Powiązania:
https://bibliotekanauki.pl/articles/110165.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
siliceous manganese ore
characterization
leaching
corncob
H2SO4
Opis:
In this study, corncob was used as reductant for sulfuric acid leaching of manganese ore from Daweezi, Upper Mohmand Agency, Pakistan. X-ray diffraction of representative powdered samples revealed the presence of manganese silicate MnSiO(SiO4), calcite (CaCO3), and -quartz (SiO2). X-ray diffraction and energy dispersive spectroscopy analyses indicated that the examined manganese ore was siliceous in nature. Three process parameters were investigated in the present study including the particle size of the ore, leaching temperature, and amount of corncob. Manganese extraction of 92.48 wt% was achieved for a leaching time of 60 min at 90 oC using 1.9 mol/dm3 H2SO4 concentration and 4 g of corncob. The present results demonstrated that corncob is a low cost, renewable, and non-hazardous reducing agent for manganese leaching under mild acid conditions in comparison to the other available reagents.
Źródło:
Physicochemical Problems of Mineral Processing; 2016, 52, 1; 56-65
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spatial distribution of early blight disease on tomato, climatic factors and bioefficacy of plant extracts against Alternaria solani
Autorzy:
Hussain, A.
Ali, S.
Abbas, H.
Ali, H.
Khan, S.W.
Powiązania:
https://bibliotekanauki.pl/articles/12689876.pdf
Data publikacji:
2019
Wydawca:
Uniwersytet Przyrodniczy w Lublinie. Wydawnictwo Uniwersytetu Przyrodniczego w Lublinie
Tematy:
Pakistan
plant cultivation
tomato
vegetable
climatic factor
bioefficacy
plant extract
plant pathogen
Alternaria solani
plant disease
blight
early blight
field survey
spatial distribution
spatial analysis
Geographic Information System
Opis:
Information on the spatial variability in plant disease is essential for location-based disease management. In the current study, the spatial distribution of tomato early blight disease was ascertained in District Gilgit, GilgitBaltistan, Pakistan. The comprehensive field survey was carried in two growing seasons (2014–2015), whereas in each growing season, 62 tomato fields were surveyed. Based on the distribution of disease, the respective thematic maps (incidence and severity) were prepared using Arc Map 10.1 with spatial analyst function of Arc GIS software by means of the inverse distance weight (IDW) interpolation method. Results indicate that early blight of tomato is spatially distributed in both growing seasons. However, in the first growing season, the disease incidence ranged from 10.22% to 44.16% and during later season 14.03–49.16%, whereas 5.37–16.40% and 6.52–26.94% severity was recorded. Furthermore, this information indicates that higher disease infestation occurred in 2015 in relation to 2014. This information linked to metrological data (temperature, precipitation and relative humidity), seemingly favored the early blight development during the growing period. Seven botanical extracts were tested against pathogen Alternaria solani at different concentrations (4, 6 and 8%). Results revealed that all tested plant extracts showed antifungal activities. However, at 8% concentration of plant extract, Datura starmonium, Berberis orthobotry, Podophyllum emodi and Uretica dioica exhibited >60%, while Peganum harmala, Artemisia maritima and Capparis spinosa <60% antifungal properties. The information generated due to this study could help the tomato growers regarding disease management and selection of resistant cultivars, improving profitability and food security in the Gilgit region.
Źródło:
Acta Scientiarum Polonorum. Hortorum Cultus; 2019, 18, 6; 29-38
1644-0692
Pojawia się w:
Acta Scientiarum Polonorum. Hortorum Cultus
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Unsteady hydromagnetic flow of Oldroyd-B fluid over an oscillatory stretching surface: a mathematical model
Autorzy:
Khan, S. U.
Ali, N.
Powiązania:
https://bibliotekanauki.pl/articles/297856.pdf
Data publikacji:
2017
Wydawca:
Uniwersytet Warmińsko-Mazurski w Olsztynie
Tematy:
Oldroyd-B fluid
oscillatory stretching sheet
homotopy analysis method
Opis:
In the present work, we have studied an unsteady, two-dimensional boundary layer flow of a magnetohydrodynamics (MHD) Oldroyd-B fluid over an oscillatory stretching surface. The problem is modeled by using constitutive equations. The number of independent variables in the governing equations are reduced by using appropriate dimensionless variables. The analytical solution is computed by using homotopy analysis method. The influences of various physical parameters such as Deborah numbers, ratio of angular frequency to stretching rate parameter and Hartmann number on time-series of velocity and transverse velocity profiles at different time instants are investigated and discussed quantitatively with the help of various graphs. It is observed that amplitude of velocity increases by increasing ratio of oscillating frequency to stretching rate parameter while decreases by increasing Hartmann number. It is further observed that the magnitude of velocity decreases by increasing Hartmann number and Deborah numbers in the terms of relaxation time parameter.
Źródło:
Technical Sciences / University of Warmia and Mazury in Olsztyn; 2017, 20(1); 87-100
1505-4675
2083-4527
Pojawia się w:
Technical Sciences / University of Warmia and Mazury in Olsztyn
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical analysis of the compositional graded quaternary barrier AlGaN-based ultraviolet-C light-emitting diode
Autorzy:
Malik, S.
Usman, Muhammad
Hussain, M.
Munsif, M.
Khan, S.
Rasheed, S.
Ali, S.
Powiązania:
https://bibliotekanauki.pl/articles/1818198.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Stowarzyszenie Elektryków Polskich
Tematy:
ultraviolet
light-emitting diodes
efficiency
quantum wells
Opis:
The compositional graded quaternary barriers (GQBs) instead of ternary/conventional quantum barriers (QBs) have been used to numerically enhance the efficiency of AlGaN-based ultraviolet light-emitting diode (LED). The performance of LED with GQBs is examined through carrier concentrations, energy band diagrams, radiative recombination, electron and hole flux, internal quantum efficiency (IQE), and emission spectrum. As a function of the operating current density, a considerable reduction in efficiency droop is observed in the device with composition-graded quaternary barriers as compared to the conventional structure. The efficiency droop in case of a conventional LED is ~77% which decreased to ~33% in case of the proposed structure. Moreover, the concentration of electrons and holes across the active region in case of the proposed structure is increased to ~156% and ~44%, respectively
Źródło:
Opto-Electronics Review; 2021, 29, 3; 80--84
1230-3402
Pojawia się w:
Opto-Electronics Review
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 110

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