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1

Internal quantum efficiency improvement of InGaN/GaN multiple quantum well green light-emitting diodes

Zhou Q., Xu M., Wang H.

Opto-Electronics Review

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2016

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Vol. 24, No. 1

1--9

EN

In recent years, GaN-based light-emitting diode (LED) has been widely used in various applications, such as RGB lighting system, full-colour display and visible-light communication. However, the internal quantum efficiency (IQE) of green LEDs is significantly lower than that of other visible spectrum LED. This phenomenon is called “green gap”. This paper briefly describes the physical mechanism of the low IQE for InGaN/GaN multiple quantum well (MQW) green LED at first. The IQE of green LED is limited by the defects and the internal electric field in MQW. Subsequently, we discuss the recent progress in improving the IQE of green LED in detail. These strategies can be divided into two categories. Some of these methods were proposed to enhance crystal quality of InGaN/GaN MQW with high In composition and low density of defects by modifying the growth conditions. Other methods focused on increasing electron-hole wave function overlap by eliminating the polarization effect.

2

Dark and singular optical solitons with competing nonlocal nonlinearities

Zhou Q., Liu L., Zhang H., Mirzazadeh M., Bhrawy A. H., Zerrad E., Moshokoa S., Biswas A.

Optica Applicata

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2016

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Vol. 46, nr 1

79--86

EN

In this work, we study the dynamics of optical solitons in a synthetic nonlocal nonlinear media. The nonlinear dynamical model which describes the propagation of optical solitons in the weakly nonlocal nonlinear media with parabolic law nonlinearity is investigated analytically. The tool of integration that is the Riccati equation mapping approach is introduced to extract exact traveling wave solutions. As a result, an explicit dark soliton, singular soliton and periodic solutions are derived.

3

Novel Green Dyeing Process of Soybean Protein/Poly(vinyl alcohol) Blend Fibre

Lv J., Zhou Q., Gao D., Liu G., Wang C.

Fibres & Textiles in Eastern Europe

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2015

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Vol. 23, no. 5 (113)

55--59

EN

A water-soluble chitosan derivative N-[(2-hydroxy-3-trimethylammonium)propyl] chitosan chloride (HTCC) was prepared and used for the modification of soybean protein/poly (vinyl alcohol) blend fiber (SPF). The dying properties of modified SPF with Cibacron FN series reactive dyes were discussed in relation to a salt-free and alkaline/acidic denaturalization dyeing bath (green dyeing process). Results showed that dye exhaustion in the green dyeing process was obviously higher than that in the conventional dyeing process, despite the addition of a large amount salt in the latter case. However, the washing fastness of SPF treated with HTCC in the green dyeing process was inferior to that of untreated SPF in the conventional dyeing process. COD (chemical oxygen demand) values of the green dyeing process effluent were found to be decreased compared with conventional dyeing effluent, which indicated that the green dyeing process could decrease the amount of toxicity of dyeing effluent remarkably.

PL

Przygotowano rozpuszczalną w wodzie mieszankę pochodnej chitozanu - chlorek N-[(2-hydroksy-3-trimetyloamono)propylo] chitozanu (HTCC). Zastosowano ją dla modyfikacji mieszanki sojowych włókien proteinowych z PVA. Następnie badano właściwości barwienia zmodyfikowanych włókien za pomocą barwników reaktywnych Cibacron seria FN zastosowanych w kąpieli bezsolnej i zasadowo/kwasowej denaturalizacyjnej kąpieli (ekologiczny proces barwienia). Wyniki wskazały, że wyczerpanie barwnika w procesie ekologicznego barwienia było zasadniczo wyższe niż to przy barwieniu konwencjonalnym, niezależnie od dodatku dużej ilości soli w tym ostatnim. Jednakże odporność na pranie włókien barwionych w procesie ekologicznym była niższa w stosunku do procesu konwencjonalnego. Stwierdzono że wartość COD (chemiczne zapotrzebowanie tlenu) w przypadku ścieków z ekologicznego barwienia była niższa w porównaniu do ścieków z barwienia konwencjonalnego, co wskazuje, że proces ekologicznego barwienia może w znacznym stopniu zmniejszyć toksyczność ścieków.

4

Optical solitons in birefringent fibers with parabolic law nonlinearity

Zhou Q., Zhu Q., Biswas A.

Optica Applicata

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2014

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Vol. 44, nr 3

399--409

EN

This paper studies the propagation of optical solitons through birefringent fibers with parabolic law nonlinearity. The Hamiltonian perturbations that are inter-modal dispersion, self-steepening, third-order dispersion and nonlinear dispersions are taken into account. Both, Riccati equation expansion method and Jacobian elliptic equation expansion method are used. Finally, analytical solutions that are Jacobian elliptic periodic traveling wave solutions, periodic solutions, unbounded solutions, singular solutions, bright and dark soliton solutions are obtained under several constraint conditions.

5

Investigation on Chaotic Characteristic of PD Magnitude Series during Propagation of Electrical tree in XLPE Power Cables

Liao R., Wang K., Liu L., Zhou T., Zhou Q.

Przegląd Elektrotechniczny

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2012

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R. 88, nr 5b

213-217

EN

The electrical tree propagation experiments were performed under high voltages with a frequency of 50Hz and amplitudes ranging from 12kV to 21kV at room temperature by utilizing an actual XLPE cable as the test sample, where the concentration of electrical field was simulated by a metal needle tip. The chaotic theory was introduced to analyze the PD magnitude series during the propagation process of electrical tree. Experimental results show that deterministic chaos exists in the propagation of electrical tree in XLPE cables, and the largest Lyapunov exponent and correlation of the strange attractors increase with the decrease of electrical tree fractal dimension. The results may provide a new approach for online diagnosis of electrical tree morphology.

PL

rzedstawiono wynika badania wyładowania w kablu XPLE przy częstotliwości 50 Hz i napięciu 12 – 21 kV. Stwierdzono chaotyczny charakter drzewienia elektrycznego. Zaproponowano opis teoretyczny umożliwiający łatwe rozpoznanie typu wyładowania.