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节理粗糙度系数的分形估算

地质科学译丛 1992年第1期9卷 85-90页

作者：谢和平 willian g.pariseau 王建锋王仁铎中国矿业大学 University of Utah. 315 WBB SaltLake City Utah 84112

节量剖面粗糙度可以被认为是具有有限生长的分形结构。为了模拟节理粗糙度，基于传统的科契曲线，本文建立了节理剖面的广义分形模型。根据节理凸起体的平均基底长度L^*和平均高度h^*两参数，可直接得到节理剖面的分维数，即：D=log4/lo... 详细信息

节量剖面粗糙度可以被认为是具有有限生长的分形结构。为了模拟节理粗糙度，基于传统的科契曲线，本文建立了节理剖面的广义分形模型。根据节理凸起体的平均基底长度L^*和平均高度h^*两参数，可直接得到节理剖面的分维数，即：D=log4/log[2(1+cos tan^-1(2h/L)]，此分维数D与节理粗糙度系数具有密切关系。其经验关系是：JRC＝85．2671（D－1）^0.5679。因此，可以说本文所提出的分形分析技术为估算JRC值提供了一种新的方法。

关键词：节理粗糙度系数分形结构岩石力学抗剪强度

Comparison of closure measurements with finite element model results in an underground coal mine in central Utah

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International Journal of Mining Science and Technology 2019年第1期29卷 9-15页

作者： William g.pariseau Michael K.McCarter Jessica M.Wempen Department of Mining Engineering University of Utah

Quantitative analysis of mine-wide subsidence at the kilometer scale and details of stress distribution about an advancing longwall face are estimated using an adaptation of the finite element method. The method is well suited to the tasks at hand. For greater realism, variability of strata properties is taken into account as are the effects of joints and cleats on elastic moduli and strengths. Evolution of pillar stress and entry closure remote from the face is readily quantified in a series of analyses that simulate face advance. Computed results compare favorably with the evolution of closure measurements about an instrumented pillar in a two-entry headgate. The appropriateness of the finite element method is confirmed. This method is based on first principles that avoid empirical schemes of uncertain applicability and numerical models ‘‘calibrated" by fitting computer output to mine measurements.

关键词： Finite element modeling Longwall mining Mine subsidence Stress modeling

User-friendly finite element design of main entries, barrier pillars,and bleeder entries

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International Journal of Mining Science and Technology 2018年第1期28卷 3-10页

作者： William g.pariseau Mark K.Larson Heather E.Lawson Douglas R.Tesarik Department of Mining Engineering University of Utah Spokane Mining Research Division NIOSH

This contribution describes development and application of a user-friendly finite element program,UT3PC, to address three important problems in underground coal mine design:(1) safety of main entries,(2) barrier pillar size needed for entry protection, and(3) safety of bleeder entries during the advance of an adjacent longwall *** the finite element method is by far the most popular engineering design tool of the digital age, widespread use by the mining community has been impeded by the relatively high cost of and the need for lengthy specialized training in numerical *** of UT3PC overcomes these impediments in three easy ***, a material properties file is prepared for the considered ***, mesh generation is automatic through an interactive process.A third and last step is simply execution of the *** using data from several western coal mines illustrate the ease of using the application for analysis of main entries, barrier pillars, and bleeder entry safety.

关键词： Finite element Coal Mine layout design Main entries Barrier pillars Bleeder entries

Whole-mine subsidence over tabular deposits and related seismicity

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International Journal of Mining Science and Technology 2017年第1期27卷 171-177页

作者： pariseau William g. McCarterr Michael K. Department of Mining Engineering University of UtahSalt Lake CityUTUSA

The challenge of estimating mine-wide subsidence and linkages to seismicity over tabular deposits is addressed by a special finite element technique(dual node–dual mesh). Subsidence and mine-induced seismicity begins near the face when caving occurs and propagates to the surface as extraction reaches a critical extent. Thus, the challenge is to obtain details at the face at the meter scale and also at the surface over the whole mine at the kilometer scale. Interactions between old and new sections of a mine are automatically taken into account with this technique. The finite element method is well established technology based on fundamentals of physical laws, kinematics and material laws. With this technique, no empirical ‘‘scaling" or fitting computer output by input data ‘‘adjustment" to mine measurements is necessary. Capability is demonstrated for doing practical whole-mine subsidence analysis from first principles. Mine-induced seismicity is shown to correlate well with face advance and element failure.

关键词： Whole mine subsidence Multi-scale Finite element analysis Mine induced seismicity

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岩石节理粗糙系数(JRC)的分形估计

中国科学（B辑） 1994年第5期24卷 524-530页

作者：谢和平 W.g.pariseau 中国矿业大学数力系 The University of Utah S. L. C. Utah 84112

根据传统的Koch曲线,我们建立了节理剖面的理论分形模型来模拟节理剖面的粗糙性。由这个模型,节理的分形维数D可以直接由两个统计参数L*和h*(这里L*和h*分别为节理粗糙度的平均基长和平均高度)来估计,即 D=log4/log[2(1+costg^(-1)(2h*/... 详细信息

根据传统的Koch曲线,我们建立了节理剖面的理论分形模型来模拟节理剖面的粗糙性。由这个模型,节理的分形维数D可以直接由两个统计参数L*和h*(这里L*和h*分别为节理粗糙度的平均基长和平均高度)来估计,即 D=log4/log[2(1+costg^(-1)(2h*/L*))]。这个分形维数很强地相关于岩石节理粗糙系数(JRC)值: JRC=85.2671(D-1)^(0.5679)。这样本文所提出的分形分析为岩石力学中JRC值的定量估计提供了一个新的方法。

关键词：岩石节理分形估计粗糙系数

Raman probing carbon&aqueous electrolytes interfaces and molecular dynamics simulations towards understanding electrochemical properties under polarization conditions in supercapacitors

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Journal of Energy Chemistry 2021年第9期30卷 279-292页

作者： Rafael Vicentini Leonardo M.Da Silva Débora V.Franco willian g.Nunes Juliane Fiates gustavo Doubek Luís F.M.Franco Renato g.Freitas Cristiano Fantini Hudson Zanin Advanced Energy Storage Division Carbon Sci-Tech LabsUniversity of CampinasAv Albert Einstein 400CampinasSP 13083-852Brazil Department of Chemistry Federal University of Jequitinhonha and Mucuri’s ValleyRodovia MGT 367km 5835000Alto da Jacuba39.100-000 DiamantinaMGBrazil Advanced Energy Storage Division Center for Innovation on New EnergiesLaboratory of Advanced BatteriesSchool of Chemical EngineeringUniversity of Campinas(UNICAMP)CampinasSP 13083-852Brazil Department of Chemistry Federal University of Mato GrossoICET-UFMT78060-900 CuiabáMTBrazil Departamento de Física ICExUniversidade Federal de Minas GeraisBelo HorizonteMG 31270-901Brazil

Raman probing of carbon electrode and electrolyte under dynamic conditions is performed here using different aqueous electrolytes to elucidate the fundamental events occurring in electrochemical supercapacitor during charge–discharge *** areal capacitance ranges from 1.54 to 2.31μF cm^(-2)μm and it is determined using different *** findings indicate that the Helmholtz capacitance governs the overall charge-storage process instead of the space charge(quantum)capacitance commonly verified for HOPg electrodes in the range of~3 to 7μF cm^(-2).Molecular dynamics simulations are employed to elucidate the origin of the reversible Raman spectral changes during the charge–discharge processes.A correlation is verified between the reversible Raman shift and the surface excesses of the different ionic species.A theoretical framework is presented to relate the effect of the applied potential on the Raman shift and its correlation with the surface ionic *** is proposed that the Raman shift is governed by the interaction of solvated cations with graphite promoted by polarization *** is the first time that a comparative study on different aqueous electrolyte p H and cation ion size has been performed tracking the Raman spectra change under dynamic polarization conditions and contrasting with comprehensive electrochemistry and dynamic molecular simulations *** study shines lights onto the charge-storage mechanism with evidence of Kohn anomaly reduction in the carbon electrode during the reversible adsorption/desorption and insertion/extraction of ionic species.

关键词： Defect reorganization in graphite Surface excess of charge Operando Raman studies Electrical double-layer capacitors

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岩爆的分形特征和机理

岩石力学与工程学报 1993年第1期12卷 28-37页

作者：谢和平 W.g.pariseau 中国矿业大学美国犹他大学

本文应用分形几何和损伤力学研究了岩爆诱发的微地震。使用分形的数目—半径关系考察了已报导的微地震事件的位置分布,发现它具有集聚(cluster)分形结构。当接近一个主岩爆时,微地震事件的集聚程度明显增加,并相应地出现分形维数值的减... 详细信息

本文应用分形几何和损伤力学研究了岩爆诱发的微地震。使用分形的数目—半径关系考察了已报导的微地震事件的位置分布,发现它具有集聚(cluster)分形结构。当接近一个主岩爆时,微地震事件的集聚程度明显增加,并相应地出现分形维数值的减小。最低的分形维数值通常出现在一个主岩爆临近产生之时。这样,分形维数的变化就有可能用来进行岩爆的预测预报。这种变化与地震学中强震发生前的降维现象(b值减小)是完全一致的,我们使用损伤力学和分形概念从理论上分析了岩爆的分形和物理机理。研究表明:一个强的破坏(岩爆或地震)实际上等效于岩体内破裂的一个分形集聚。这个破裂的分形集聚所需能量耗散E随分形维数D的减小而按指数律增加:D=C_1exp[—C_2E]这样,岩爆和地震的分形自然在理论上得到很好的解释,并由此人们能更好地去理解岩爆和地震的发生和发展。

关键词：地震分形特征分形机理岩石爆炸

Characterization of porous cobalt hexacyanoferrate and activated carbon electrodes under dynamic polarization conditions in a sodium-ion pseudocapacitor

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Journal of Energy Chemistry 2021年第3期30卷 53-62页

作者： Bruno Morandi Pires willian goncalves Nunes Bruno guilherme Freitas Francisca Elenice Rodrigues Oliveira Vera Katic Cristiane Barbieri Rodella Leonardo Morais Da Silva Hudson Zanin Advanced Energy Storage Division Manufacturing CroupCarbon Sci-Tech LabsCenter for Innovation on New EnergiesUniversity of CampinasCampinas 13083-852SPBrazil Brazilian Synchrotron Light Laboratory(LNLS/Brazilian Center of Energy and Materiab(CNPEM)) Campinas 13083-970SPBrazil Department of Chemistry Laboratory of Fundamental and Applied ElectrochemistryFederal University of Jequitinhonha and Mucuri's VatleyAlto dajacuba 39100-000Diamantina-MGBrazil

We report here the activated carbon and cobalt hexacyanoferrate composite,which is applied as the electrode materials in symmetric supercapacitors containing a 1.0 M Na_(2)SO_(4) aqueous *** novel material combines high specific surface area and electrochemical stability of activated carbon with the redox properties of cobalt hexacyanoferrate,resulting in maximum specific capacitance of 329 F g^(-1) with large voltage working window of 2.0 *** studies indicated that cobalt hexacyanoferrate introduces important pseudocapacitive properties accounting for the overall charge-storage process,especially when Ig^(-1).At lower gravimetric currents(e.g.,0.05 A g^(-1))and up to 1.0 V,the presence of cobalt hexacyanoferrate improves the specific energy for more than 300%.In addition,to better understanding the energy storage process we also provided a careful investigation of the electrode materials under dynamic polarization conditions using the in situ Raman spectroscopy and synchrotron light Xray diffraction *** complementary findings were obtained in these *** believe that this novel electrode material is promising for applications regarding the energy-storage process in pseudocapacitors with long lifespan properties.

关键词： Operando studies Raman XRD synchrotron light Cobalt hexacyanoferrate Activated carbon High specific capacitance

Optimization of the Electrospinning Conditions by Box-Behnken Design to Prepare Poly(Vinyl Alcohol)/Chitosan Crosslinked Nanofibers

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Journal of Materials Science and Chemical Engineering 2020年第4期8卷 13-31页

作者： Vinícius R. Viana willian H. Ferreira Edwin g. Azero Marcos L. Dias Cristina T. Andrade Instituto de Macromoléculas Professora Eloisa Mano Universidade Federal do Rio de Janeiro Centro de Tecnologia Bloco J Rio de Janeiro Brazil Departmento de Ciências Naturais Universidade Federal do Estado do Rio de Janeiro Avenida Pasteur Rio de Janeiro Brazil

Electrospun poly(vinyl alcohol)/chitosan nanofibers had their solution and process parameters optimized using a Box-Behnken design and desirability function. Four factors (applied voltage, flow rate, distance tip-to-plate and amount of chitosan) were varied to produce electrospun mats with a low fiber diameter. An empirical model was developed for each response using response surface methodology (RSM), which revealed that flow rate had no significant influence on the assessed responses. With desirability function, the optimal conditions to produce the nanofibers were applied voltage of 13.1 kV, 30% chitosan concentration and distance tip-to-plate of 10 cm. The fiber diameter and standard deviation were 196.5 ± 28.3 nm, compared to the predicted values of 185.9 ± 26.8 nm. The desirability function allied with Box-Benhken design proved themselves important tools to predict process parameters for the development of nanofibers. The mats were crosslinked with glutaraldehyde for 24 h and 48 h and presented good water stability and enhanced mechanical properties.

关键词： Electrospinning Poly(Vinyl Alcohol) Chitosan Box-Behnken Design