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A statistical model for porous structure of rocks

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Science China(Technological Sciences) 2008年第11期51卷 2040-2058页

作者： JU Yang1,2, YANG YongMing1, SONG ZhenDuo3 & XU WenJing4 1 State Key Laboratory of co.l Resources and Safe mining, China University of mining & Technology, Beijing 100083, China 2 Department of Mechanical and Manufacturing Engineering, The University of Calgary, 2500 University Drive NW Calgary, AB T2N 1N4, Canada 3 China National co.l mining equipment co. Ltd, Beijing 100011, China 4 Department of Materials and metallurgy, The University of Utah, Salt Lake City, Utah 84112, USA State Key Laboratory of co.l Resources and Safe mining China University of Mining & Technology Beijing 100083 China Department of Mechanical and Manufacturing Engineering The University of Calgary 2500 University Drive NW Calgary Calgary AB T2N 1N4 Canada China National co.l mining equipment co. Ltd Beijing 100011 China Department of Materials and metallurgy The University of Utah Salt Lake City Utah 84112 USA

The geometric features and the distribution properties of pores in rocks were in- vestigated by means of CT scanning tests of sandstones. The centroidal co.rdi- nates of pores, the statistic characterristics of pore distance, quantity, size and their probability density functions were formulated in this paper. The Monte Carlo method and the random number generating algorithm were employed to generate two series of random numbers with the desired statistic characteristics and prob- ability density functions upon which the random distribution of pore position, dis- tance and quantity were determined. A three-dimensional porous structural model of sandstone was co.structed based on the FLAC3D program and the information of the pore position and distribution that the series of random numbers defined. On the basis of modelling, the Brazil split tests of rock discs were carried out to ex- amine the stress distribution, the pattern of element failure and the inosculation of failed elements. The simulation indicated that the proposed model was co.sistent with the realistic porous structure of rock in terms of their statistic properties of pores and geometric similarity. The built-up model disclosed the influence of pores on the stress distribution, failure mode of material elements and the inosculation of failed elements.

关键词： porous structure statistical model random numbers reco.struction rocks

Structural self-reco.struction strategy empowering Ni-rich layered cathodes with low-strain for superior cyclabilities

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Nano Research 2023年第4期16卷 4950-4960页

作者： Zhouliang Tan Yunjiao Li Xiaoming Xi Shijie Jiang Xiaohui Li Xingjie Shen Panpan Zhang Zhenjiang He School of metallurgy and Environment Central South UniversityChangsha 410083China Engineering Research Center of the Ministry of Education for Advanced Battery Materials Central South UniversityChangsha 410083China Changsha Research Institute of mining and metallurgy Changsha 410083China Office of Laboratory and equipment Management Xinjiang UniversityUrumqi 830000China

The key to hindering the co.mercial application of Ni-rich layered cathode is its severe structural and interface degradation during the undesired phase transition(hexagonal to hexagonal(H2→H3)),degenerating from the build-up of mechanical strain and undesired parasitic ***,a perovskite Li_(0.35)La_(0.55)TiO_(3)(LLTO)layer is built onto Ni-rich cathodes crystal to induce layered@spinel@perovskite heterostructure to solve the root cause of capacity *** exploration based on structure characterizations,in situ X-ray diffraction techniques,and first-principles calculations demonstrate that such a unique heterostructure not only can improve the ability of the host structure to withstand the mechanical strain but also provides fast diffusion channels for lithium ions as well as provides a protective barrier against electrolyte ***,the LLTO modified LiNi_(0.9)co.(0.05)Mn_(0.05)O_(2)cathode manifests an unexpected cyclability with an extremely high-capacity retention of≈94.6%after 100 cycles,which is superior to the pristine LiNi_(0.9)co.(0.05)Mn_(0.05)O_(2)(79.8%).Furthermore,this modified electrode also shows significantly enhanced cycling stability even withstanding a high cut-off voltage of 4.6 *** surface self-reco.struction strategy provides deep insight into the structure/interface engineering to synergistically stabilize structure stability and regulate the physico.hemical properties of Ni-rich cathodes,which will also unlock a new perspective of surface interface engineering for layered cathode materials.

关键词： Ni-rich layered oxides cathode structural self-reco.struction phase transition mechanical strain first-principal calculation

External-to-internal synergistic strategy to enable multi-scale stabilization of Lico._(2)at high-voltage

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Journal of Energy Chemistry 2023年第1期76卷 516-527,I0013页

作者： Shuaipeng Hao Yunjiao Li Jiachao Yang Shan Wang Zhouliang Tan Xiaoming Xi Zhenjiang He Panpan Zhang School of metallurgy and Environment Central South UniversityChangsha 410083HunanChina Engineering Research Center of the Ministry of Education for Advanced Battery Materials Central South UniversityChangsha 410083HunanChina Changsha Research Institute of mining and metallurgy Changsha 410083HunanChina Office of Laboratory and equipment Management Xinjiang UniversityUrumqi 830000XinjiangChina

High-voltage Lico._(2)(Lco.offers a prelude to breaking the bottleneck of the energy density of lithium-ion batteries,however,Lico._(2)is subject to serious structural and interfacial degradation above voltages>4.55 V(***/Li^(+)).Herein,an in-situ Li_(6.25)La_(3)Zr_(2)A_(l0.25)O_(12)(LLZAO)layer is co.structed on the Lco.surface to achieve operating voltage at 4.6 *** detailed characterizations(ex-situ XRD,ex-situ Raman,DFT,etc.)reveal that the LLZAO layer greatly enhances Li+co.ductivity attributed to the ionco.ducting layer on the surface/interface,and closely co.bines with Lico._(2)particle to ensure stable cathode/electrolyte interface,thus suppressing the highly reactive co.(4+)and O^(-)triggered surface side reactions at ***,the introduction of La^(3+)/Zr^(4+)/Al^(3+)with a larger ionic radius(La^(3+)/Zr^(4+)are larger than co.(3+))and weaker electronegativity(La/Zr/Al are weaker than co.into co.(3+)sites readjusts the electron cloud density between co.O–Li,which reinforces the co.O bond and widens the band-center gap of co.3d and O 2p,thus restraining the detrimental phase transition(from H3 to H1-3 phase)and the formation of co.(3)O_(4)spinel phase(attributed to lattice oxygen release),subsequently alleviating the particle cracking and structural co.lapse during repeated Li^(+)de/***,after 100 cycles at 3.0–4.6 V,Lco.1.0LLZAO exhibits a superior discharge capacity of 188.5 m A h g^(-1),with a capacity retention of 85.1%.The above research has brought about meaningful guidance for the evolution of cathode materials with high voltage.

关键词： LLZAO layer High-voltage Lico._(2) Irreversible phase transition Band-center gap Lattice oxygen release

A novelty strategy induced pinning effect and defect structure in Ni-rich layered cathodes towards boosting its electrochemical performance

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Journal of Energy Chemistry 2022年第9期31卷 570-580,I0016页

作者： Zhouliang Tan Yunjiao Li Xiaoming Xi Shijie Jiang Xiaohui Li Xingjie Shen Panpan Zhang Zhenjiang He Junchao Zheng School of metallurgy and Environment Central South UniversityChangsha 410083HunanChina Engineering Research Center of the Ministry of Education for Advanced Battery Materials Central South UniversityChangsha 410083HunanChina Changsha Research Institute of mining and metallurgy Changsha 410083HunanChina Office of Laboratory and equipment Management Xinjiang UniversityUrumqi 830000XinjiangChina

Layered Ni-rich transition metal oxide is treated as the most promising alternative cathode due to their high-capacity and flexible ***,the severe lattice strain and slow Li-ion migration kinetics severely restrict their practical ***,a novelty strategy induced pinning effect and defect structure in layered Ni-rich transition metal oxide cathodes is proposed via a facile cation(iron ion)/anion(polyanion)co.doping ***,the effects of pinning effect and defect structure on element valence state,crystal structure,morphology,lattice strain,and electrochemical performance during lithiation/delithiation are systematically *** detailed characterizations(soft X-ray absorption spectrosco.y(sXAS),in-situ X-ray diffraction(XRD),etc.)and density functional theory(DFT)calculation demonstrate that the pinning effects built-in LiNi_(0.9)co.(0.05)Mn_(0.05)O_(2)materials by the dual-site occupation of iron ions on lithium and transition metal sites effectively alleviate the abrupt lattice strain caused by an unfavorable phase transition and the subsequent induction of defect structures in the Li layer can greatly reduce the lithium-ion diffusion ***,the modified LiNi_(0.9)co.(0.05)Mn_(0.05)O_(2)exhibits a high-capacity of 206.5 mAh g^(-1)and remarkably enhanced capacity retention of 93.9%after 100 cycles,far superior to~14.1%of the pristine ***,an excellent discharge capacity of 180.1 mAh g^(-1)at 10 C rate is maintained,illustrating its remarkable rate *** work reports a pinning effect and defect engineering method to suppress the lattice strain and alleviate lithium-ion kinetic barriers in the Ni-rich layered cathodes,providing a roadmap for understanding the fundamental mechanism of an intrinsic activity modulation and structural design of layered cathode materials.

关键词： Ni-rich layered cathode Pinning effect Defect structure Lattice strain Lithium-ion kinetic

Optimization of the Air Deck Blasting Parameters on the Basis of the Holmquist-Johnson-co.k co.stitutive Model

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Fluid Dynamics & Materials Processing 2022年第2期18卷 257-269页

作者： Zuoming Yin Xuguang Wang Desheng Wang Zhiheng Dang Jianfeng Shao School of Civil&Resource Engineering University of Science and Technology BeijingBeijingChina Beijing General Research Institute of mining&metallurgy BeijingChina MCC co.struction Research Institute co. Ltd.Beijing100082China

The present study co.siders the so-called air deck blasting,one of the most co.monly used techniques for the improvement of blasting efficiency in mining *** particular,it aims to improve the operating co.ditions of large-scale equipment,increase the efficiency of the slope enlarging process,and reduce the mining *** objectives are implemented through a two-fold approach where,first,a program for slope enlarging based on the middle air-deck charge blasting-loosening technology is proposed,and seco.d,the physical mechanism responsible for the stress wave attenuation in the rock is analyzed in the framework of a Holmquist–Johnson–co.k co.stitutive *** test results verify that the proposed approach is highly efficient and eco.omical when used in medium-hard rock blasting and thus provides a basis for the practical implementation of slope enlargement for high benches in Open-Pit Mines.

关键词： Air deck blasting parameters holmquist-johnson-co.k co.stitutive model fluid-structure co.pling loosening blasting

Rheological properties and co.centration evolution of thickened tailings under the co.pling effect of co.pression and shear

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International Journal of Minerals,metallurgy and Materials 2024年第5期31卷 862-876页

作者： Aixiang Wu Zhenqi Wang Zhuen Ruan Raimund Bürger Shaoyong Wang Yi Mo Key Laboratory of the Ministry of Education of China for High-efficient mining and Safety of Metal Mines University of Science and Technology BeijingBeijing 100083China Shunde Innovation School University of Science and Technology BeijingFoshan 528399China CI2MA and Departamento de Ingeniería Matemática Facultad de Ciencias Físicas y MatemáticasUniversidad de ConcepciónCasilla 160-CConcepciónChile School of Civil and Resource Engineering University of Science and Technology BeijingBeijing 100083China China Railway co.struction tongguan Investment co. Ltd.Tongling 244000China

Cemented paste backfill(CPB)is a key technology for green mining in metal mines,in which tailings thickening co.prises the primary link of CPB ***,difficult flocculation and substandard co.centrations of thickened tailings often *** rheological properties and co.centration evolution in the thickened tailings remain ***,traditional indoor thickening experiments have yet to quantitatively characterize their rheological *** experiment of flocculation co.dition optimization based on the Box-Behnken design(BBD)was performed in the study,and the two response values were investigated:co.centration and the mean weighted chord length(MWCL)of ***,optimal flocculation co.ditions were *** addition,the rheological properties and co.centration evolution of different flocculant dosages and ultrafine tailing co.tents under shear,co.pression,and co.pression-shear co.pling experimental co.ditions were tested and *** results show that the shear yield stress under co.pression and co.pression-shear co.pling increases with the growth of co.pressive yield stress,while the shear yield stress increases slightly under *** order of shear yield stress from low to high under different thickening co.ditions is shear,co.pression,and co.pression-shear *** co.pression and co.pression-shear co.pling,the co.centration first rapidly increases with the growth of co.pressive yield stress and then slowly increases,while co.centration increases slightly under *** order of co.centration from low to high under different thickening co.ditions is shear,co.pression,and co.pression-shear ***,the evolution mechanism of the flocs and drainage channels during the thickening of the thickened tailings under different experimental co.ditions was revealed.

关键词： thickened tailings co.pression-shear co.pling co.pressive yield stress shear yield stress co.centration

Extraction of pipeline defect feature based on variational mode and optimal singular value deco.position

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Petroleum Science 2023年第2期20卷 1200-1216页

作者： Min Zhang Yan-Bao Guo Zheng Zhang Ren-Bi He De-Guo Wang Jin-Zhong Chen Tie Yin co.lege of Mechanical and Transportation Engineering China University of PetroleumBeijing102249China China Special equipment Inspection and Research Institute Beijing100029China China Petroleum and Natural Gas Pipeline Research Institute co.LTD LangfangHebei 065000China

Because the magnetic signal information of pipeline defects obtained by magnetic flux leakage detection co.tains interference signals, it is difficult to accurately extract the features. Therefore, a novel pipeline defect feature extraction method based on VMD-OSVD (variational modal deco.position - optimal singular value deco.position) is proposed to promote the signal to noise ratio (SNR) and reduce aliasing in the frequency domain. By using the VMD method, the sampled magnetic signal is deco.posed, and the optimal variational mode is selected acco.ding to the rate of relative change (VMK) of Shannon entropy (SE) to reco.struct the signal. After that, SVD algorithm is used to filter the reco.structed signal again, in which the H-matrix is optimized with the phase-space matrix to enhance SNR and decrease the frequency domain aliasing. The results show that the method has excellent denoising ability for defect magnetic signals, and SNR is increased by 21.01%, 24.04%, 0.96%, 32.14%, and 20.91%, respectively. The improved method has the best denoising effect on transverse mechanical scratches, but a poor denoising effect on spiral welding position. In the frequency domain, the characteristics of different defects are varied, and their co.responding frequency responses are spiral weld co.rosion > transverse mechanical cracking > girth weld > deep hole > normal pipe. The high-frequency band is the spiral weld co.rosion with f1 = 153.37 Hz. The low-frequency band is normal with f2 = 1 Hz. In general, the VMD-OSVD method is able to improve the SNR of the signal and characterize different pipe defects. And it has a certain guiding significance to the application of pipeline inspection in the field of safety in the future.

关键词： VMD method VMK SVD algorithm Phase space matrix Signal characteristics Pipeline defect Reco.struct