检索结果-南通市图书馆

Higher order asymptotic behaviour of partial maxima of random sample from generalized Maxwell distribution under power normalization

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics(A Journal of Chinese Universities) 2018年第2期33卷 177-187页

作者： HUANG jian-wen WANG jian-jun School of Mathematics and Statistics Southwest University Research Center for Artificial Intelligence & Education Big Data Southwest University

In this article, the higher order asymptotic expansions of cumulative distribution function and probability density function of extremes for generalized Maxwell distribution are established under nonlinear normalization. As corollaries, the convergence rates of the distribu- tion and density of maximum are obtained under nonlinear normalization.

关键词： higher order expansion extreme generalized Maxwell distribution nonlinear normalization

The role of Debye mass in the chiral crossover in a strong magnetic field

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2022年第10期74卷 68-75页

作者： Jia Zhang Xin-jian wen Institute of Theoretical Physics State Key Laboratory of Quantum Optics and Quantum Optics DevicesShanxi UniversityTaiyuanShanxi 030006China

In this paper,the Debye mass of quarks is investigated in the Nambu–Jona-Lasinio model at zero and nonzero chemical *** a uniform plasma,the Debye mass usually behaves as a monotonous increasing function of the temperature,the chemical potential and the magnetic *** the fixed coupling interaction G,we find that the magnetic catalysis(MC)on the occurrence of the chiral restoration could be revealed by the susceptibility of the Debye mass dmD/dT at low chemical potential and by the quantity TdmD/dT in the region of moderate ***,the inverse MC is realized under a thermomagnetic coupling constant G(B,T)by the behavior of the Debye mass at both zero and nonzero chemical potentials.

关键词： chiral restoration strong magnetic field Debye mass Nambu-Jona-Lasinio

Extraction of niobium, yttrium, and cerium from a low-grade niobium-bearing ore by roasting(NH_4)_2SO_4-Na_2SO_4-H_2SO_4 system

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2014年第6期33卷 754-760页

作者： wen-Cheng Gao jian-Kang wen Biao Wu He Shang National Engineering Laboratory of Biohydrometallurgy General Research Institute for Nonferrous Metals

A novel process of extracting niobium, yttrium,and cerium from a low-grade niobium-bearing ore by the roasting（NH4）2SO4-Na2SO4-H2SO4 system was experimentally studied. The influences of various factors,such as roasting temperature, roasting time, mass ratio of agents-to-ore and particle size fraction on the extraction of valuable metals were comprehensively investigated. It is found that the roasting Na2SO4-H2SO4 system is effective to extract the niobium, yttrium, and cerium. The obtained optimum conditions for the extraction of Nb, Y, and Ce are roasting temperature of 300 °C, roasting time of 3 h, mass ratio of Na2SO4：H2SO4：Ore of 0.5：1.0：1.0, and particle size fraction of-74 lm（~95 %）. Under the optimum condition, the maximum recovery of Nb, Y, and Ce can reach90.53 %, 92.15 %, and 98.04 %, respectively. All the results generated from this study will provide the fundamentals for Nb, Y, and Ce extraction from a niobiumbearing ore with low-grade.

关键词： Extraction Niobium Yttrium Cerium Lowgrade

Mechanism of Mg2+ dissolution from olivine and serpentine: Implication for bioleaching of high-magnesium nickel sulfide ore at elevated pH

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2019年第9期26卷 1069-1079页

作者： jian-zhi Sun jian-kang wen Bo-wei Chen Biao Wu National Engineering Laboratory of Biohydrometallurgy GRINM Group Corporation Limited

To inhibit the dissolution of Mg^2+ during the bioleaching process of high-magnesium nickel sulfide ore, the effect of major bioleaching factors on the dissolution of Mg^2+ from olivine and serpentine was investigated and kinetics studies were carried out. The results indicated that the dissolution rate-controlling steps are chemical reaction for olivine and internal diffusion for serpentine. The most influential factor on the dissolution of Mg^2+ from olivine and serpentine was temperature, followed by p H and particle size. A novel method of bioleaching at elevated pH was used in the bioleaching of Jinchuan ore. The results showed that elevated pH could significantly reduce the dissolution of Mg^2+ and acid consumption along with slightly influencing the leaching efficiencies of nickel and cobalt. A model was used to explain the leaching behaviors of high-magnesium nickel sulfide ore in different bioleaching systems. The model suggested that olivine will be depleted eventually, whereas serpentine will remain because of the difference in the rate-controlling steps. Bioleaching at elevated pH is a suitable method for treating high-magnesium nickel sulfide ores.

关键词： olivine serpentine high-magnesium nickel sulfide ore bioleaching shrinking core model elevated pH

A novel approach to extract Nb,Y and Ce from a niobium-bearing ore of low grade by roasting KHSO_(4)-H_(2)SO_(4) system

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2021年第7期40卷 1979-1986页

作者： wen-Cheng Gao jian-Kang wen Biao Wu He Shang Xue Liu National Engineering Laboratory of Biohydrometallurgy GRIMAT Engineering Institute Co.LtdBeijing 101407China GRINM Resources and Environment Tech.Co. LtdBeijing 101407China

In this work,a novel approach of leaching valuable metals,such as niobium,yttrium and cerium,from a niobium-bearing ore of low grade by roasting KHSO_(4)-H_(2)SO_(4)system was experimentally *** the work,the effects of roasting temperature,roasting time,mass ratio of agents to ore and the types of leaching agents on the extraction of Nb,Y and Ce were investigated,and the roasting KHSO_(4)-H_(2)SO_(4)-ore system was thought as an effective method to extract these valuable *** was found that the recovery of Nb,Y and Ce can,respectively,reach 90.20%,97.22%and 98.41%in condition of roasting temperature of 300℃,roasting time of 2 h,mass ratio of KHSO_(4)-to-H_(2)SO_(4)to ore of 0.5:1:1,particle size of-74 lm(~95%),leaching solution of oxalic acid(30 g·L^(-1)),leaching temperature of 90℃and leaching liquid-to-solid ratio of 5:*** leaching kinetics of the calcined Nb-bearing ore in oxalic acid solution was successfully modeled by chemical reaction model,and the apparent activity energy was obtained to be14.16 kJ·mol^(-1).The results generated from this work will provide the fundamentals for extracting Nb,Y and Ce from a niobium-bearing ore of low grade and have potential applications value in future.

关键词： Roasting Extraction Niobium Yttrium Cerium Low grade

Generalized system for strongly g-r-pseudomonotonic nonlinear variational inequalities in Hilbert spaces

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics(A Journal of Chinese Universities) 2010年第1期25卷 63-68页

作者： YANG Xin-bo PENG jian-wen Department of Computer Science Chongqing Education College Chongqing 400067 China College of Mathematics and Computer Science Chongqing Normal University Chongqing 400047China

The approximation solvability of a generalized system for strongly g-r- pseudomonotonic nonlinear variational inequalities in Hilbert spaces is studied based on the convergence of the projection method. The results pr... 详细信息

关键词： Projection method strong g-r-pseudomonotonicity variational inequality convergence.

Sulfuric acid leaching of low-grade refractory tantalum–niobium and associated rare earths minerals in Panxi area of China

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2015年第3期34卷 202-206页

作者： Biao Wu He Shang jian-Kang wen National Engineering Laboratory of Biohydrometallurgy General Research Institute for Nonferrous Metals

By mineral liberation analyzer （MLA） automated quantitative system, the niobium-tantalum ore in this study was classified as refractory mineral of low-grade which was mainly composed of fergusonite, polycrase, ilmenorutile, and bastnasite. Most of niobium and rare earth metals were dis- seminated in these minerals （particle sizes of 95 % rare earth elements 〈40 μm）, which cannot be concentrated through traditional floatation process and treated by the current hydrofluoric acid leaching in industry application. It is nec- essary to develop a new approach to recovery these valuable metals. In this study, an improved method is proposed to extract these metals, which includes acid roasting and sulfuric acid leaching. The influence of mineralogy, acid concentra- tion, leaching temperature, leaching time, and liquid to solid ratio was experimentally studied. It is observed that after the ground ore （-74 μm） was roasted at 350 ℃ for 2 h with sulfuric acid （18.4 mol.L- 1） in the ore to acid mass ratio of 1：1, and then the roasting residue reacted with 25 % sulfuric acid at 90 ℃ for 2 h, the recovery rate of rare earth elements reaches 〉90 %, and the leaching extent of niobium can reach 84 %.

关键词： Niobium-tantalum Rare earth Refractory Low-grade Roasting Sulfuric acid leaching

Reproduced Giant Localization Length of Two-Side Surface Disordered Nanowires with Long-Range Correlation

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2011年第10期28卷 184-187页

作者： ZHAO Wei DING jian-wen Department of Physics&Institute for Nanophysics and Rare-earth Luminescence Xiangtan UniversityXiangtan 411105

We numerically investigate the normalized localization length of two-side rough nanowires as functions of energy,magnetic field and correlation strength by using modular recursive Green's function *** is found that in the absence of correlation,while in the presence of magnetic field,the localization length increases linearly for two-side roughness,which is different to diverging exponentially for one-side ***,the localization of electrons is suppressed in the low energy region,but enhanced in the high energy *** the presence of correlation,especially,an exponential enhancement in the localization length resumes in high energy region,in contrast to that in low energy region,the long-range correlations abnormally enhance the localization of electrons.A competitive mechanism is proposed to explain this behavior.

关键词： nanowires roughness resume

Artifact-centric workflow management system

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

计算机集成制造系统 2011年第8期17卷 1709-1721页

作者： SUN Yu-tian LIU Xi KUCUKOGUZ Esra SU jian-wen YANG jian University of California Santa Barbara CA 93106-5110 USA Nanjing University Nanjing 210093 China Macquarie University Sydney NSW 2109 Australia

Data-centric modeling approach for workflow specification and design has received considerable attention from research and development *** architecture for a workflow management system named EZFLOWS was *** components... 详细信息

关键词： workflow artifact-centric modeling business process management