Autor: Chen, Hang - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: Beneficiation of Ga from alunite concentrates by selective acid leaching and alkaline precipitation
Autorzy:: Zhu, Mao-Lan
Chen, Hang
Zhong, Shui-Ping
Huang, Zhong-Sheng
Chen, Xi
Hu, Zhi-Biao
Powiązania:: https://bibliotekanauki.pl/articles/110733.pdf
Data publikacji:: 2019
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:: gallium
selective leaching
precipitation
alunite concentrate
Opis:: In this study beneficiation of Ga from alunite ore was investigated. The effects of the calcination temperature, H₂SO₄ concentration, leaching temperature and liquid-solid ratio on the dissolution characteristic of Ga, K and Al were studied. The results showed that increasing the calcination temperature, H₂SO₄ concentration and leaching temperature can improve the solubility of K and Al. However, higher H₂SO₄ concentration and lower leaching temperature can improve the dissolution of Ga, which was beneficial to recovery of Ga. On the basis of the solubility difference in H₂SO₄, a two-stage process of selective acid leaching and alkali precipitation of Ga was proposed. The concentration of Ga was increased significantly from 54 g/t in alunite ore to 4100 g/t in alkali precipitation product. The major elements of Al and K in alunite were recovered as the alum crystal with a purity of 99.62%.
Źródło:: Physicochemical Problems of Mineral Processing; 2019, 55, 4; 1028-1038
1643-1049
2084-4735
Pojawia się w:: Physicochemical Problems of Mineral Processing
Dostawca treści:: Biblioteka Nauki

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Tytuł:: Effect of mining and geology on mining-induced seismicity – a case study
Autorzy:: Khalil, Heba
Chen, Tuo
Xu, Yu-Hang
Mitri, Hani
Powiązania:: https://bibliotekanauki.pl/articles/2201413.pdf
Data publikacji:: 2022
Wydawca:: Główny Instytut Górnictwa
Tematy:: underground mining
mining-induced seismicity
moment tensor inversion
magnitude-frequency distribution
górnictwo podziemne
sejsmiczność indukowana górnictwem
inwersja tensora momentu
rozkład wielkościowo-częstotliwościowy
Opis:: Mining-induced seismicity is a commonly occurring phenomenon in underground mines. This poses a greater challenge to the safety of the mining operation. This paper presents a case study of the Young-Davidson mine in northern Ontario, Canada, where seismic events of magnitude Mn 2.0+ have been observed at mining depths of 600 to 800 m below the surface. The occurrence of large seismic events at such shallow depths is the key issue of this study. A comprehensive study of the microseismic database has been conducted to discern the root causes for the unusually strong seismic activities recorded at shallow depths. The effects of mining activities in the vicinity of two dykes intersecting the orebody on the seismic response are investigated. Variation of the b-value derived from the magnitude-frequency distribution is examined, and moment tensor inversion for three large seismic events is carried out to determine the source mechanisms. It is shown from this investigation that the influence of the sill pillar is more critical, leading to high mining-induced stress and the occurrence of large events. While the findings from this research are specific to this case study, they could be used to shed light on the causes of induced seismicity at other mines with similar conditions.
Źródło:: Journal of Sustainable Mining; 2022, 21, 3; 200--215
2300-1364
2300-3960
Pojawia się w:: Journal of Sustainable Mining
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Double-image encryption algorithm based on discrete fractional angular transform and fractional Fourier transform
Autorzy:: Qiu, Tian
Dai, Wei-Hua
Chen, Su-Hua
Zhou, Hang
Gong, Li-Hua
Powiązania:: https://bibliotekanauki.pl/articles/2172857.pdf
Data publikacji:: 2022
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:: chaotic system
fractional transform
discrete fractional angular transform
double-image encryption
Opis:: By combining fractional Fourier transform with discrete fractional angular transform, a double-image encryption algorithm is designed. The discrete cosine transform is performed on two grayscale images to generate a spectrum image, and then the generated spectrum image is compressed into an image with Zigzag scanning. The compressed image is processed with the discrete fractional angular transform, and then fractional Fourier transform and double random phase coding are executed on the image. The DNA operation controlled by chaotic system is introduced to change the pixel values. Finally, the ciphertext image is obtained through bit-level permutation and pixel adaptive diffusion. The statistical information of the plaintext images is employed as the input of the SHA-256 to calculate the initial conditions of the chaotic map. Simulation experiments demonstrate that the double-image encryption algorithm can effectively reduce the correlation among adjacent pixels of the plaintext images.
Źródło:: Optica Applicata; 2022, 52, 4; 669--684
0078-5466
1899-7015
Pojawia się w:: Optica Applicata
Dostawca treści:: Biblioteka Nauki

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