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Wyszukujesz frazę "Khan, Muhammad Usman" wg kryterium: Autor


Wyświetlanie 1-4 z 4
Tytuł:
Investigation of the Effects of the Incident Flow Angle on Vibration Behavior in Heat Exchanger Tube Bundle
Autorzy:
Usman, Muhammad
Khushnood, Shahab
Nizam, Luqman Ahmad
Tanveer, Waqas
Shafi, Ahmad
Ayub, Muhammad
Khan, Hassan Farid
Rustam, Behzad
Powiązania:
https://bibliotekanauki.pl/articles/102083.pdf
Data publikacji:
2019
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
incident flow angle
fluid elastic instability
flow-induced vibration
parallel triangular array
cross flow velocity
flexible tube
kąt przepływu
niestabilność sprężysta płynu
drgania indukowane przepływem
równoległy układ trójkątny
prędkość przepływu poprzecznego
elastyczna rura
Opis:
An experimental study on the incident flow angle effects on the vibration behavior was carried out on aluminum tube in parallel triangular tube bundle with P/D ratio of 1.375. Fluid elastic instability is the most fatal mechanism from all the vibration mechanisms and therefore must be dealt with a lot of attention. Experiments were performed on low speed water tunnel with the velocity of water ranges from 0.3 m/s to 0.7 m/s. The experiments were designed in a unique way to study the effects of incident flow angle on the vibration behavior. The monitored tube was mounted flexibly in an array of rigid tubes. The experiments were conducted on a flexible tube for different velocities ranging from 0.3 m/s to 0.7 m/s with different array rotated angles (0 to 90 degrees). It was observed that the vibration level was significantly high at 75 degree configuration as compared to other rotated angle configurations. It was also observed that the damping response is dispersed with all positive values, indicating that there is no instability in the tube.
Źródło:
Advances in Science and Technology. Research Journal; 2019, 13, 2; 186-194
2299-8624
Pojawia się w:
Advances in Science and Technology. Research Journal
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Role of ergonomics in the selection of stemming plugs for surface mining operations
Autorzy:
Rehman, Atta Ur
Emad, Muhammad Zaka
Khan, Muhammad Usman
Powiązania:
https://bibliotekanauki.pl/articles/220328.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
ergonomia
piaskowanie
korek spustowy
wiercenie
wydobycie
kamieniołom
ergonomics
blasting
stemming plugs
drilling
mining
limestone quarry
Opis:
Stemming plugs are one of the widely used accessory in surface mining operations. Stemming plugs assist conventional stemming material in gas retention and help in better fragmentation and explosive utilization. Effective use of the stemming plugs results in economic benefits and enhance the efficacy of the project. Economic and productive viability of stemming plugs have been conducted in depth by different researchers. Addition of stemming plugs to a new system requires ergonomic challenges for operators conducting drilling and blasting operation. Induction of a newer product in already established system is subject to overall positive feedback. This work investigates ergonomics of three different stemming plugs introduced to a limestone quarry in Pakistan. The stemming plugs were evaluated based on extra time needed, workers feedback, failures during operation, recovery time after failure and number of extra equipment required to carry out the operation. Points based matrix was established with likeliness of each plug and based on overall scores stemming plug 1 was most acceptable followed by stemming plug 3. Stemming plug 2 was disliked by operation and did not reach the level of acceptability of operators. This work will help stemming plug making industry in adapting to best practices by incorporating ergonomics of plugs in designing. Literature shows no previous work on ergonomics of stemming plugs.
Źródło:
Archives of Mining Sciences; 2020, 65, 1; 59-70
0860-7001
Pojawia się w:
Archives of Mining Sciences
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
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/1818193.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 1-4 z 4

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