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1

Study on mine ventilation resistance coefficient inversion based on genetic algorithm

Gao K., Deng L., Liu J., Wen L., Wong D., Liu Z.

Archives of Mining Sciences

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2018

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Vol. 63, no. 4

813--826

EN

The frictional resistance coefficient of ventilation of a roadway in a coal mine is a very important technical parameter in the design and renovation of mine ventilation. Calculations based on empirical formulae and field tests to calculate the resistance coefficient have limitations. An inversion method to calculate the mine ventilation resistance coefficient by using a few representative data of air flows and node pressures is proposed in this study. The mathematical model of the inversion method is developed based on the principle of least squares. The measured pressure and the calculated pressure deviation along with the measured flow and the calculated flow deviation are considered while defining the objective function, which also includes the node pressure, the air flow, and the ventilation resistance coefficient range constraints. The ventilation resistance coefficient inversion problem was converted to a nonlinear optimisation problem through the development of the model. A genetic algorithm (GA) was adopted to solve the ventilation resistance coefficient inversion problem. The GA was improved to enhance the global and the local search abilities of the algorithm for the ventilation resistance coefficient inversion problem.

PL

Współczynnik oporu oporu wentylacji jezdni w kopalni węgla jest bardzo ważnym parametrem technicznym w projektowaniu i renowacji wentylacji kopalnianej. Obliczenia oparte na wzorach empirycznych i badaniach terenowych w celu obliczenia współczynnika oporu mają ograniczenia. W niniejszym badaniu proponuje się inwertowaną metodę obliczania współczynnika oporu wentylacji kopalni za pomocą kilku reprezentatywnych danych dotyczących przepływu powietrza i ciśnienia w węzłach. Model matematyczny metody inwersji jest opracowywany na zasadzie najmniejszych kwadratów. Zmierzone ciśnienie i obliczone odchylenie ciśnienia wraz z zmierzonym przepływem i obliczonym odchyleniem przepływu są uwzględniane przy określaniu obiektywnej funkcji, która obejmuje również ciśnienie w węźle, przepływ powietrza i ograniczenia współczynników oporu wentylacji. Problem odwrotności współczynnika oporu wentylacji został przekształcony w nieliniowy problem optymalizacji poprzez opracowanie modelu. Zastosowano algorytm genetyczny (GA) w celu rozwiązania problemu inwersji współczynnika oporu wentylacji. GA został ulepszony w celu zwiększenia globalnych i lokalnych możliwości wyszukiwania algorytmu problemu odwrotności współczynnika oporu wentylacji.

2

Flotation behavior of nickel sulfide ore in a cyclonic flotation column

Deng L., Li G., Cao Y., Ma Z.

Physicochemical Problems of Mineral Processing

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2017

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Vol. 53, iss. 2

770--780

EN

This study aimed to show the flotation behavior of a nickel sulfide ore in a cyclonic flotation column. The flotation experiments were carried out using a sample of nickel sulfide ore obtained from a mineral processing plant of China. Representative samples collected from the feed, concentrate, tailing, and circulation middling were sieved using a cyclonic particle analyzer to collect different size fractions for analysis. The function of the column cyclonic zone of was evaluated by comparing the quality of tailing and circulation middling. The flotation results showed that the concentrate with Ni grade of 1.78% and recovery of 65.56% was obtained under given test conditions. The content of main sulfide minerals and coarse particles in the circulation middling was higher than that in the tailing. The results indicated that, unlike conventional cyclone classification, separation achieved in the cyclonic zone of the column was not dependent on the particle size and density. Sulfide minerals with good floatability were easily captured by bubbles and moved toward the center of the column, even if these particles were coarser and heavier.

3

Study on Improvement of Main Protection for Converter Ground Faults for Some HVDC Projects in China

Deng L., Dongyun S., Yinhong L.

Przegląd Elektrotechniczny

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2013

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R. 89, nr 5

128-134

EN

The dc differential protection with one stage needs to react all inverter ground faults under various fault conditions in some HVDC projects in China. The protection setting values of action value and delay time are set low and short, respectively, in order to satisfy the protection speedy and sensitivity, which reduces the protection reliability and induces protection mal-operation. Based on the relationship between fault influence level and protection action quantity, this paper improved the dc differential protection from one stage to two stages, in wihich high-value and low-value stages are used to guarantee the protection speedy and the protection sensitivity and reliability, respectively. Then, by using analysis results from the characteristics of inverter ground fault and the influence of ground resistance, this paper obtained the worst fault conditions, which helped setting calculation of the two-stage protection improved. The PSCAD/EMTDC simulation model of Guiguang II HVDC Project was established and used to verify the improvement on the main protection for converter ground faults. The simulation results showed that the improvement was correct and reasonable, and can be helpful to resolve the contradiction among the speedy, sensitivity and reliability of protection performance.

PL

W artykule przedstawiono ulepszony sposób ochrony różnicowoprądowej dla układów HVDC. W rozwiązaniu zastosowano dwa stopnie ochrony, wysoki i niski, w celu zapewnienia odpowiedniej szybkości, czułości i odporności układu. Na podstawie charakterystyk zwarć doziemnych w falownikach oraz wpływu rezystancji uziemienia, wyznaczono najgorszy przypadek awarii. Wykonano badania symulacyjne, proponowanego rozwiązania, które potwierdziły skuteczność działania.

4

Research on absorption spectroscopy of CH4 around 1,315um

Shao J., Gao X., Deng L., Huang W., Yang Y., Pei S., Yuan Y., Zhang W.

Optica Applicata

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2005

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Vol. 35, nr 1

155-162

EN

Measurements have been made about the absorption features of Ch4 around 1.315 um by using the second harmonic detwction technique of tunable diode laser with multipass cell (white). Studies concerning the second harmonic detecyion technique of CH4 around 1.65 um have been widely reported currently, but reports about the absorption features in NIR spectra of CH4 around 1.315 um can scarcely be found. We have performed a detailed study about the absorption features of CH4 around 1.315 um and we presents the results here. We give the line positions, the line intensties and self-broadening coefficients near 1.315 um at a pressure of 0.077 torr.