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1

Numerical analysis of the compositional graded quaternary barrier AlGaN-based ultraviolet-C light-emitting diode

Malik S., Usman Muhammad, Hussain M., Munsif M., Khan S., Rasheed S., Ali S.

Opto-Electronics Review

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2021

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Vol. 29, No. 3

80--84

EN

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.

2

LMPP Effects on Morphology, Crystallization, Thermal and Mechanical Properties of iPP/LMPP Blend Fibres

Hussain M., Zhu F., Yu B., Han J., Memon H., Yasin S.

Fibres & Textiles in Eastern Europe

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2018

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Vol. 26, no. 2 (128)

26--31

EN

The thermal properties and morphological characterisation of isotactic polypropylene (iPP) homopolymer and its blends with low molecular low modulus polypropylene (LMPP) were studied. Firstly blends were prepared with variant LMPP contents, and their properties were characterised using SEM, DSC, XRD, and DMA. Later the mechanical properties of iPP/LMPP blend fibres were investigated. SEM results showed that the iPP/LMPP blends produced smoother surfaces when the LMPP content was increased, as well as the miscibility. All the Tg values with different LMPP percentages were in-between pure iPP and LMPP. The XRD results indicated the LMPP percentage decreased along with the degree of crystallinity of the iPP/LMPP blends (5% to 15%), which increased and then decreased as compared to pure iPP. The elongation at break increased when the LMPP content increased, with the maximum elongation at break of the LMPP 25% blend reaching 12.95%, which showed great stretch-ability, whereas the elastic modulus of iPP/LMPP blends decreased.

PL

W pracy badano właściwości termiczne i morfologię homopolimeru izotaktycznego polipropylenu (iPP) i jego mieszanek z polipropylenem o małej masie cząsteczkowej (LMPP). Zastosowano następujące proporcje mieszania iPP/LMPP (wt/wt): 95/5, 90/10, 85/15, 80/20 i 75/25, zdefiniowano je odpowiedni: 5%, 10%, 15 %, 20% i 25%. Właściwości włokien mieszanych iPP/LMPP porównano do właściwości czystego PP i LMPP. Włókna mieszane zbadano za pomocą SEM, DSC, XRD i DMA. Następnie zbadano mechaniczne właściwości włókien iPP/LMPP. Wyniki SEM wykazały, że wraz ze zwiększeniem zawartości LMPP powierzchnia włókien charakteryzowała się większą gładkością. Wszystkie wartości Tg włókien mieszanych były pośrednie pomiędzy czystym iPP i LMPP. Stwierdzono, że wydłużenie przy zerwaniu zwiększyło się wraz ze wzrostem zawartości LMPP, przy maksymalnym wydłużeniu przy zerwaniu 12,95%, dla włókien z zawartością 25% LMPP, co wskazywało na dużą rozciągliwość, podczas gdy moduł sprężystości wzdłużnej włókien iPP / LMPP zmniejszył się.

3

Effect of Shale Distribution on Hydrocarbon Sands Integrated with Anisotropic Rock Physics for AVA Modelling: A Case Study

Ali A., Zubair, Hussain M., Rehman K., Toqeer M.

Acta Geophysica

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2016

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Vol. 64, no. 4

1139--1163

EN

Shales can be distributed in sand through four different ways; laminated, structural, dispersed and any combination of these aforementioned styles. A careful analysis of well log data is required for the determination of shale distribution in sand affecting its reservoir quality. The objective of this study is to characterize the effect of shale distribution on reservoir quality of sands using well log data. The correlation of well data in terms of lithology has revealed four sand and three shale layers in Lower Goru Formation acting as a major reservoir in the study area. Our results indicate that the laminated type of shale distribution prevails at the Basal sand level, which does not affect its reservoir quality greatly. The remaining layers of variable vertical extent show a variety of shale distribution models affecting their reservoir quality adversely. We also present anisotropic rock physics modelling for AVA analysis at Basal sand level.

4

Influence of annealing on structural, morphological and optical properties of Cd x Zn1-x O nanopowder prepared by Co-precipitation method

Ali F. M., Abu-Assy M. K., El-Gazzar S., Iqbal M., Hussain M.

Materials Science Poland

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2012

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Vol. 30, No. 3

248--253

EN

Structural and optical properties of Cd x Zn1-x O (x = 0.0, 0.025, 0.050, 0.075, 0.1) nanopowder, synthesized by co-precipitation method have been investigated. The effect of annealing on the structural and morphological properties was studied using X-ray diffraction. The samples with x = 0.0 up to 0.075 exhibit wurtzite hexagonal phase, whereas, the sample with x = 0.1 shows two phases: wurtzite hexagonal ZnO and cubic CdO phase. This behavior is explained on the basis of solubility of CdO in ZnO. Energy Dispersive X-ray analysis (EDX) results revealed the existence of Cd, Zn, and O elements in the nanopowder. Transmission Electron Microscopy (TEM) images confirm that the particle size of the prepared samples is in nano range. The optical band gap values obtained from the absorption spectra show that absorption depends on Cd composition. By doping of ZnO with CdO, a red shift in the absorption edge was observed.

5

LOD modelling of polygonal models

Hussain M., Okada Y.

Machine Graphics and Vision

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2005

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Vol. 14, No. 3

325-343

EN

An automatic edge-collapse based simplification method has been proposed for decimation of polygonal models and generating their LODs (Levels of detail). The measure of geometric fidelity employed is motivated by the normal space deviation of a polygonal model arising during its decimation process and forces the algorithm to minimize the normal space deviation. In spite of the global nature of the evaluation of geometric deviation, the algorithm is memory efficient and involves less execution time then the state-of-the art simplification algorithms. This automatically prevents the creation of folds and automatically preserves visually important features of the model even at low levels of detail. LODs generated by our method compare favorably with those produced by the standard QEM-based algorithm QSlim in terms of the mean and maximum geometric errors, whereas its performance in preserving normal space of the original model is better than that of QSlim.