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Wyszukujesz frazę "Qureshi, S." wg kryterium: Autor


Wyświetlanie 1-9 z 9
Tytuł:
Local accuracy and error bounds of the improved Runge-Kutta numerical methods
Autorzy:
Qureshi, S.
Memon, Z.
Shaikh, A. A.
Powiązania:
https://bibliotekanauki.pl/articles/122862.pdf
Data publikacji:
2018
Wydawca:
Politechnika Częstochowska. Wydawnictwo Politechniki Częstochowskiej
Tematy:
error estimate
remainder term
principal error function
truncation error
Lotkin bound
granice błędu
metoda numeryczna Runge-Kutty
błąd obcięcia
granica Lotkina
funkcja błędu
szacowanie błędu
Opis:
In this paper, explicit Improved Runge-Kutta (IRK) methods with two, three and four stages have been analyzed in detail to derive the error estimates inherent in them whereas their convergence, order of local accuracy, stability and arithmetic complexity have been proved in the relevant literature. Using single and multivariate Taylor series expansion for a mathematical function of one and two variables respectively, slopes involved in the IRK methods have been expanded in order to obtain the general expression for the leading or principal term in the local truncation error of the methods. In addition to this, principal error functions of the methods have also been derived using the idea of Lotkin bounds which consequently gave rise to the error estimates for the IRK methods. Later, these error estimates were compared with error estimates of the two, three, and four-stage standard explicit Runge-Kutta (RK) methods to show the better performance of the IRK methods in terms of the error bounds on the constant step-size h used for solving the initial value problems in ordinary differential equations. Finally, a couple of initial value problems have been tested to determine the maximum absolute global errors, absolute errors at the final nodal point of the integration interval and the CPU times (seconds) for all the methods under consideration to get a better idea of how the methods behave in a particular situation especially when it comes to analyzing the error terms.
Źródło:
Journal of Applied Mathematics and Computational Mechanics; 2018, 17, 4; 73-84
2299-9965
Pojawia się w:
Journal of Applied Mathematics and Computational Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A simple semi-analytical model for the Kink effect for the intrinsic n-channel polysilico thin film transistors
Autorzy:
Siddiqui, M. J.
Qureshi, S.
Alshariff, S. M.
Powiązania:
https://bibliotekanauki.pl/articles/378435.pdf
Data publikacji:
2007
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Technologii Elektronowej
Tematy:
cienkie warstwy
tranzystory
jonizacja
pole elektryczne
model analityczny
efekt Kinka
polisilikon
thin films
tranzistors
ionization
electric field
analylical model
Kink effect
polysilicon
Opis:
In order to improve the modeling of Polysilicon thin film transistors (Poly-Si-TFTs) a precise evaluation of the excess current due to impact ionization is needed. In this paper we have proposed a simple model for the excess current resulting from the impact ionization occurring at high drain biases. Model is based on the estimation of the electric field in the saturated part of the channel. The electric field in the saturated region is obtained by the solution of the two- dimensional Poisson's equation. The model is semi-analytical and uses only one fitting parameter which is desirable for circuit simulation. The simulation results with the developed impact ionization current model are in excellent agreement with the available experimental output characteristics of the intrinsic n-channel Poly-Si-TFTs.
Źródło:
Electron Technology : Internet Journal; 2007, 39, 1; 1-4
1897-2381
Pojawia się w:
Electron Technology : Internet Journal
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A New Approach to Parametric Modeling of Glottal Flow
Autorzy:
Qureshi, T. M.
Syed, K. S.
Powiązania:
https://bibliotekanauki.pl/articles/177068.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
control volumes
spring-mass system
vocal folds
Rosenberg glottal model
LF glottal model
Opis:
Glottal waveform models have long been employed in improving the quality of speech synthesis. This paper presents a new approach for modeling the glottal flow. The model is based on three control volumes that strike a one-mass and two-springs system sequentially and generate a glottal pulse. The first, second and third control volumes represent the opening, closing and closed phases of the vocal folds, respectively. The masses of the three control volumes and the size of the first one are the four parameters that define the shape, pitch and amplitude of the glottal pulse. The model may be viewed as parametric approach governed by second order differential equations rather than analytical functions and is very flexible for designing a glottal pulse. The glottal pulse generated by the present model, when compared with those generated by Rosenberg, LF and mucosal wave propagation models demonstrates that it appropriately represents the opening, closing and closed phases of the vocal fold oscillation. This leads to the validity of our model. Numerical solution of the present model has been found to be very efficient as compared to its analytical solution and two other well-known parametric models Rosenberg++ and LF. The accuracy of the numerical solution has been illustrated with the help of analytical solution. It has been observed that the accuracy improves by increasing the size of the first control volume and may decrease insignificantly with increase in the mass of any of the control volumes. Two experiments with the present model support its successful implementation as a voice source in speech synthesis. Thus our model renders itself as an efficient, accurate and realistic choice as a voice source to be employed in real-time speech production.
Źródło:
Archives of Acoustics; 2011, 36, 4; 695-712
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A One-Mass Physical Model of the Vocal Folds with Seesaw-Like Oscillations
Autorzy:
Qureshi, T. M.
Syed, K. S.
Powiązania:
https://bibliotekanauki.pl/articles/177478.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
body-cover model
seesaw-like oscillation
glottal flow
vocal folds
spring-mass system
mucosal wave propagation
Opis:
A low-dimensional physical model of small-amplitude oscillations of the vocal folds is proposed here. The model is a simplified version of the body-cover one in which mucosal surface wave propagation has been approximated by the seesaw-like oscillation of the vocal fold about its fulcrum point whose position is adjustable in both the horizontal and vertical directions. This approach works for 180 degree phase difference between the glottal entry and exit displacements. The fulcrum point position has a significant role in determining the shape of the glottal flow. The vertical position of the fulcrum point determines the amplitude of the glottal exit displacement, while its horizontal position governs the shape and amplitude of the glottal flow. An increment in its horizontal position leads to an increase in the amplitude of the glottal flow and the time period of the opening and closing phases, as well as a decrease in the time period of the closed phase. The proposed model is validated by comparing its results with the low-dimensional mucosal surface wave propagation model.
Źródło:
Archives of Acoustics; 2011, 36, 1; 15-27
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of the use of a down-hole mechanical cleaning device for efficient wellbore cleaning
Analiza wykorzystania wgłębnych mechanicznych urządzeń czyszczących do skutecznego oczyszczania otworu
Autorzy:
Qureshi, A.
Miska, S.
Miska, W.
Powiązania:
https://bibliotekanauki.pl/articles/299975.pdf
Data publikacji:
2007
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
wiercenie
oczyszczanie dna otworu
otwory horyzontalne
drilling
down-hole mechanical cleaning
horizontal wells
Opis:
Field evidence indicates that in highly deviated and horizontal wells, cuttings tend to accumulate on the lower side of the annulus under the influence of gravity and eventually may form a non moving bed. This leads to considerable increase in equivalent circulating density (ECD) and drag/torque as well may result in a differential pipe sticking and wellbore stability problems. A good control of drilling fluid rhelogical properties, flow rate and drillpipe rotational speed may not be sufficient in some instances. Also, the commonly used techniques of circulation at high flow rates, using sweeps of high/low viscosity and high density may not be possible and, at times, prove to be ineffective. To overcome this difficulty, a down hole cleaning subs (mechanical cleaning devices - MCDs) are incorporated in the drill string to agitates the cuttings bed by bringing the cuttings into suspension for subsequent carrying out by the drilling fluid to the surface. These devices are furnished with "blades" which produce the desired hydrodynamic effects as the drill string is rotated and helps to dislodge the cuttings from the bed. The hole cleaning is thus governed primarily by the agitation created by the device, the rheological properties of the mud and the drilling fluid flow rate. Taking these factors into account, a study was conducted at Tulsa University Drilling Research Projects' (TUDRP) large scale wellbore simulator to experimentally determine the cleaning efficiency of a Mechanical Cleaning Device (MCD). From the database generated through the experiments, correlations were obtained by performing regression modeling to extend the results to field applications. These correlations are based on dimensionless parameters and predict reasonably accurately the in-situ cuttings concentration when the MCD is installed in the drill string. The results are useful for designing of the optimal hydraulic program for extended reach, high angle and horizontal wells.
Z danych terenowych wynika, że w silnie odchylonych i poziomych otworach wiertniczych zwierciny gromadzą się w dolnej części przestrzeni pozarurowej pod wpływem siły grawitacji. Prowadzi to do znacznego wzrostu ECD oraz momentu; może również spowodować zablokowanie rury oraz problemy z zachowaniem stabilności otworu. Właściwa kontrola właściwości reologicznych, wielkości przepływu i prędkości obrotowej w niektórych przypadkach może okazać się niewystarczająca. Również powszechnie stosowane techniki intensywnej cyrkulacji, a także z wykorzystaniem cieczy o wysokiej/niskiej lepkości oraz dużej gęstości mogą okazać się niemożliwe lub nieskuteczne. Do pokonania tej trudności na przewodzie zastosowano mechaniczne wgłębne urządzenie czyszczące w celu pobudzenia zwiercin i utworzenia zawiesiny, która zostanie wyniesiona na powierzchnię wraz z płuczką wiertniczą. Urządzenia tego typu wyposażone są w ostrza, które wywołują pożądany efekt hydrodynamiczny w trakcie obrotu przewodu wiertniczego, i w wyniku czego zwierciny zostają podniesione z miejsca gromadzenia się. Główne mechanizmy związane z czyszczeniem otworu polegają na wzbiciu osadu, odpowiednich właściwościach reologicznych płuczki wiertniczej oraz hydrauliki.
Źródło:
Wiertnictwo, Nafta, Gaz; 2007, 24, 1; 401-413
1507-0042
Pojawia się w:
Wiertnictwo, Nafta, Gaz
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Maintaining the feasibility of hard real-time systems with a reduced number of priority levels
Autorzy:
Qureshi, M. B.
Alrashed, S.
Min-Allah, N.
Kołodziej, J.
Arabas, P.
Powiązania:
https://bibliotekanauki.pl/articles/330305.pdf
Data publikacji:
2015
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
real time system
feasibility analysis
fixed priority scheduling
rate monotonic algorithm
online scheduling
system czasu rzeczywistego
analiza wykonalności
algorytm szeregowania
Opis:
When there is a mismatch between the cardinality of a periodic task set and the priority levels supported by the underlying hardware systems, multiple tasks are grouped into one class so as to maintain a specific level of confidence in their accuracy. However, such a transformation is achieved at the expense of the loss of schedulability of the original task set. We further investigate the aforementioned problem and report the following contributions: (i) a novel technique for mapping unlimited priority tasks into a reduced number of classes that do not violate the schedulability of the original task set and (ii) an efficient feasibility test that eliminates insufficient points during the feasibility analysis. The theoretical correctness of both contributions is checked through formal verifications. Moreover, the experimental results reveal the superiority of our work over the existing feasibility tests by reducing the number of scheduling points that are needed otherwise.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2015, 25, 4; 709-722
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fabrication and Characterization of Al6061-Nano Al2O3 Composites by Ultrasonic Assisted Stir Casting followed by Heat Treatment and Hot Forging
Autorzy:
Purohit, Rajesh
Qureshi, M.M.U.
Kumar, Ashish
Mishra, Abhishek
Rana, R.S.
Powiązania:
https://bibliotekanauki.pl/articles/28099519.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
Al6061 alloy
Al6061-Al2O3 nanocomposites
XRD analysis
FESEM
mechanical properties
automotive gears
Opis:
The present work comprises the development of Al6061/nano Al2O3 composites with 0 to 4 weight percent in steps of 0.5 wt. % of nano alumina particles by using ultrasonic assisted stir casting. Casted samples were subjected to heat treatment and hot forging. Further forged and heat-treated gear blanks of nano Al2O3 (0 to 3.0 weight %) reinforced nanocomposites were machined to make spur gears for the wear test. The results have shown that nano Al2O3 reinforcement in the Al6061 matrix with heat treatment and forging improves the hardness and compressive strength up to 3.5 wt. %, after that, it starts decreasing because of the agglomeration of nano alumina particles. SEM results reveal grain refinement of the pure alloy after reinforcement. Removal of porosity and voids observed after forging operation. Wear resistance increasing with incorporation of Al2O3 nanoparticles in base alloy, reinforcement wt. %, precipitation hardening and hot forging also improves wear resistance and mechanical properties. These composites have widespread applications in gear, brake discs, crankshaft, clutch plates, pistons, and other components of automobiles and aircraft structures.
Źródło:
Archives of Metallurgy and Materials; 2023, 68, 2; 791--798
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Pre-harvest foliar application of vegetables extract improves the quality of harvested grape
Autorzy:
Abbasi, N.A.
Kareem, A.
Hafiz, I.A.
Qureshi, A.A.
El-Gioushy, S.
Powiązania:
https://bibliotekanauki.pl/articles/12692459.pdf
Data publikacji:
2019
Wydawca:
Uniwersytet Przyrodniczy w Lublinie. Wydawnictwo Uniwersytetu Przyrodniczego w Lublinie
Tematy:
plant cultivation
grapevine
Vitis vinifera
Perlette cultivar
King Ruby cultivar
grape
fruit
vegetable extract
pre-harvest application
foliar application
total soluble solid
total phenolics content
ascorbic acid content
quality improvement
fruit quality
fruit storage
Opis:
This study focused on examining the effect of vegetables extract foliar application on storage quality of the grapes grape (Vitis vinifera L. cvs. ‘Perlette’ and ‘King’s Ruby’). The vines were sprayed after fruit set twice at 15 days interval at concentrations of 0, 0.20%, 0.30% and 0.40%. Fruit were harvested and kept under cold-storage at 0.5 ±0.5°C and 90% RH for 28 days. The physicochemical properties of treated and untreated berries were analyzed at 7 days intervals during the cold storage. The results showed that the pre-harvest application of vegetable extracts reduced the weight loss and inhibited the fruit decay. Treated grape also had higher ascorbic acid contents, total phenolics, 2,2-diphenyl-1-picrylhydrazyl-radical (DPPH) scavenging activity, and higher soluble solid contents, titratable acidity, and reduced sugar:acid ratio. The concentration of 0.30% and cultivar ‘Kings Ruby’ gave the best result as compared to untreated control. In conclusion, pre-harvest vegetables extract application on berries showed higher antioxidant activities in grape berries, and maintained their post-harvest quality. These results indicated that foliar spray of vegetables extract could effectively improve the fruit quality, mainly through the reduction of phenolic content.
Źródło:
Acta Scientiarum Polonorum. Hortorum Cultus; 2019, 18, 6; 107-117
1644-0692
Pojawia się w:
Acta Scientiarum Polonorum. Hortorum Cultus
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Collection of hospital wastewater data using deduplication approaches
Autorzy:
Khan, N. A.
Sinha, G. R.
Ahmed, S.
Feshchenko, A.
Changani, F.
Qureshi, A.
Mazhar, M. A.
Neklonskyi, I.
Powiązania:
https://bibliotekanauki.pl/articles/1818511.pdf
Data publikacji:
2020
Wydawca:
Stowarzyszenie Komputerowej Nauki o Materiałach i Inżynierii Powierzchni w Gliwicach
Tematy:
statistics
hospital wastewater
medical waste
deduplication
approaches
servers
statystyka
ścieki szpitalne
odpady medyczne
deduplikacja
podejścia
serwery
Opis:
Purpose: This investigation aims to study the various approaches currently used to reduce the load on computer servers in order to better manage data on hospital wastewater treatment and solid waste generation. Design/methodology/approach: This manuscript investigates the taxonomies of deduplication procedures based on literature and other data sources, thereby presenting its classification and its challenges in detection. Findings: Based on the literature survey of deduplication techniques, the method of deduplication dispensed on cloud gadget devices has been found to be a promising research challenge. The gaps discussed include a reduction in storage space, bandwidth, type of disks used, and expenditure on energy usage and heat emissions when implementing these strategies. The art work on a scalable, robust, green and allocated approach to deduplication for a cloud gadget will remain of interest in destiny. Research limitations/implications: Considerable attention is focused on the deduplication due to efficient, extensive storage system. Practical implications: This research paper will be useful to identify deduplication techniques which are nowadays used in different hospital wastewater data collection systems and put significant proposals for further improvements in deduplication. Originality/value: This manuscript portrays a broader assessment of the available literature for data duplication along with the classification of different methods for the data storage used in the different level of storage of hospital wastewater data collection.
Źródło:
Archives of Materials Science and Engineering; 2020, 104, 1; 5--18
1897-2764
Pojawia się w:
Archives of Materials Science and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-9 z 9

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