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Effect of longwall-induced subsurface deformations on shale gas well casing stability under deep covers

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International Journal of Mining Science and Technology 2019年第1期29卷 3-8页

作者： Daniel w.h.Su Peter zhang Mark Van Dyke Todd Minoski Center for Disease Control and Prevention(CDC) National Institute for Occupational Safety and Health(NIOSH)Pittsburgh Mining Research Division(PMRD)

This paper presents the results of a 2017 study conducted by the National Institute for Occupational Safety and health(NIOSh), Pittsburgh Mining Research Division(PMRD), to evaluate the effects of longwall-induced subsurface deformations within a longwall abutment pillar under deep cover. The 2017 study was conducted in a southwestern Pennsylvania coal mine, which extracts 457 m-wide longwall panels under 361 m of cover. One 198 m-deep, in-place inclinometer monitoring well was drilled and installed over a 45 m by 84 m center abutment pillar. In addition to the monitoring well, surface subsidence measurements and underground coal pillar pressure measurements were conducted as the 457 m-wide longwall panel on the south side of the abutment pillar was being mined. Prior to the first longwall excavation, a number of simulations using FLAC3D^(TM) were conducted to estimate surface subsidence, increases in underground coal pillar pressure, and subsurface horizontal displacements in the monitoring well. Comparisons of the pre-mining FLAC3D simulation results and the surface, subsurface,and underground instrumentation results sh.w.that the measured in-place inclinometer casing deformations are in reasonable agreement with those predicted by the 3D finite difference models. The measured surface subsidence and pillar pressure are in excellent agreement with those predicted by the 3D *** from this 2017 research clearly indicate that, under deep cover, the measured horizontal displacements within the abutment pillar are approximately one order of magnitude smaller than those measured in a 2014 study under medium cover.

关键词： Longwall Deformations Shale gas wells Casing Safety and health

NhC-mediated photocatalytic para-selective C–h acylation of aryl alcohols: regioselectivity control via remote radical spiro cyclization

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Science China Chemistry 2025年

作者： Tinglei zhang Lala wang Xiaolin Peng Tianhui Liao Dongmei Chen Ting Tu Donghan Liu Ziye Cheng Shiqing huang Shi-Chao Ren Xinglong zhang Yonggui Robin Chi State Key Laboratory of Green Pesticide Key Laboratory of Green Pesticide and Agricultural Bioengineering Ministry of Education Guizhou University Qiannan Medical College for Nationalities School of Chemistry Chemical Engineering and Biotechnology Nanyang Technological University Department of Chemistry The Chinese University of Hong Kong Institute of high Performance Computing Agency for Science Technology and Research

Friedel-Crafts reaction and transition-metal catalysis represent primary methodologies for arene acylation; h.w.ver, suffer from certain limitations, such as electronic effect-dependent reactivity, regioselectivity issues, the necessity of directing group, and relatively exceptionally limited exploration in meta-and para-acylations. N-heterocyclic carbene(NhC) catalysis has recently emerged as a promising alternative strategy for arene acylation, offering distinct regioselectivity profiles that are challenging to achieve through known methods. herein, an NhC-mediated photo-catalytic para-selective C–h acylation of aryl alcohols is disclosed. The reaction employs a remote radical-induced temporary spiro cyclization strategy, proceeding via tandem radical dearomatization, radical acylation, rearomatization processes. Combined experimental and computational mechanistic studies support the proposed reaction pathway and observe an exclusive para-selectivity regardless of the nature of the substituents on the substrates. Despite the less satisfactory yields, the current method exhibits non-electronic nature-based reactivity and regioselectivity, enabling quick access to acylated arenes that are difficult or impossible for reported methods.

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Dual-ligand chiral MOFs exhibiting circularly polarized room temperature phosphorescence for anti-counterfeiting

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Science China Chemistry 2025年

作者： hongrui Zheng Qingqing wang Xinchao wang Fei wang Shangda Li Jian zhang State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of Matter Chinese Academy of Sciences Fujian Key Laboratory of Polymer Materials College of Chemistry and Materials Science Fujian Normal University

Advanced chiral optical materials exhibiting circularly polarized room-temperature phosphorescence（CPRTP） possess significant research value. This study facilitates the synthesis of chiral metal-organic frameworks（CMOFs） with good CPRTP performance by implementing a dual-ligand strategy. By self-assembling the luminescent ligand h2BIIM with the chiral ligands L-or D-h2IDPA in the presence of Zn（II） ions, two robust three-dimensional（3D） CMOFs were successfully constructed. These complexes demonstrated intense fluorescence and exhibited prolonged yellow room-temperature phosphorescence（RTP） with a duration of up to 6 s. Notably, they exhibited both circularly polarized fluorescence(glum= ±7.57 × 10-3) and CPRTP(glum=±2.68 × 10-3). These unique properties were effectively utilized in the creation of multi-color anti-counterfeiting patterns,underscoring their promising potential for a wide range of applications.

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Breaking the structural symmetry of active sites in zeolite imidazolate framework for enhanced CO2 photoreduction

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Science China Chemistry 2025年

作者： Yupeng han Yayu Yan Qiaohong Li Xin wu Fei wang Jian zhang State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of Matter Chinese Academy of Sciences University of Chinese Academy of Sciences College of Chemistry Fuzhou University

Adjusting the structure and composition of active sites is a highly effective method for activating linear ***, precise control of interfacial chemistry within molecular-scale environments presents a significant challenge in heterogeneous catalysis. In our study, we present symmetry-broken Mo-O-Co triple-atom active sites within the hybrid zeolite imidazole framework hZIF-CoMo. These sites disrupt the electronic balance and create a weak built-in electric field, thus promoting photocatalytic CO2reduction. The CO yield over hZIF-CoMo is improved to 3.1 mmol g-1h-1, which is over four times higher than the parent cobalt-imidazole framework MAF-6-Co. Both experimental and theoretical studies indicate that electronic modulation through the symmetry-breaking Mo-O-Co moiety acts as an organizing knob to accelerate charge separation and result in more carriers participating in the catalytic reaction. This work provides important insights into optimizing site-related electronic structures for targeted photocatalytic reactions.

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Gas-Solid Flow,Combustion Characteristics,and Gas Emissions in a 75 t/h CFB Boiler Based on the CPFD Method

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Journal of Thermal Science 2025年第1期34卷 323-336页

作者： hUANG Xiankun BAI zhang ZhU Xiaoli wANG Shuoshuo MU Lin GONG Liang College of New Energy China University of Petroleum (East China) Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education School of Energy and Power EngineeringDalian University of Technology

A 3D simulation using Computational Particle Fluid Dynamics（CPFD） methods was used to calculate coal combustion in a 75 t/h industrial-scale circulating fluidized bed（CFB） *** characteristics,gas-solid flow characteristics,and gaseous pollutant emissions of CFB boilers from combustion ignition to stable operation were systematically evaluated in this *** sh.w.that the temperature distribution is relatively uniform throughout the *** the combustion process unfolds within the boiler,the gas composition curve strikingly portrays the inverse correlation between CO2and *** the combustion reaction progresses,it becomes evident that the concentration of CO2progressively increases,while the concentration of O2concurrently *** inverse relationship underscores the fundamental combustion reaction,where carbon-based fuels react with oxygen to produce carbon dioxide and release ***,a comprehensive analysis has revealed that,from ignition to stable combustion,both nitric oxide（NO） and sulfur dioxide（SO2） emissions exhibit a declining *** reduction in pollutant generation is attributed to the improvement in combustion *** complete combustion leads to lower levels of unburned hydrocarbons,which are prone to NO ***,the sulfur content in the fuel is more efficiently oxidized to sulfur trioxide（SO3） or bound in sulfates,reducing *** steady state in the simulation,the SO2mass flow rate varies significantly with the furnace height,gradually increasing from 0.07 kg·s-1at 4 m at the bottom of the furnace to a peak of 0.078 kg·s-1at 8 m in the center,and then decreasing to 0.06 kg·s-1at 20m at the top of the furnace.

关键词： Sulfur dioxide

CALCULATION OF ThE VACANCY VOLUME OF METALS BY MODIFIED BROOKS' MODEL

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Acta Metallurgica Sinica(English Letters) 2004年第6期17卷 888-893页

作者： w.h.Qi M.P.wang w.Y.hu B.w.zhang SchoolofMaterialsScienceandEngineering JiangsuUniversityZhenjiang212013China／／SchoolofMaterialsScienceandEngineeringCentralSouthUniversityChangsha410083China SchoolofMaterialsScienceandEngineering CentralSouthUniversityChangsha410083China DepartmentofAppliedPhysics HunanUniversityChangsha410082China

To modify the shape difference between the spherical vacancy and the realistic vacancy, a shape factor is introduced into Brooks' vacancy model. It is sh.w. that the modified model is more efficient in predicting the vacancy volume of metals than the original one, and the calculated vacancy volumes of 17 metals by the modified model agree with the values reported in literatures. Furthermore, the present results sh.w.that the vacancy shape may contribute 2%-9% to the whole vacancy volume.

关键词： vacancy volume shape effect metals

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Foreword

Journal of Materials Science & Technology 2014年第6期30卷 I0001-I0002页

作者： w.h.w.ng Z.F.zhang Institute of Physics Chinese Academy of Sciences at Beijing

As a new class of advanced materials, metallic glasses （also often referred as amorphous alloys） possess a combination of unique amorphous structure and remarkably impressive mechanical and physical properties, and are now at the cutting edge of research. The emergence of bulk metallic glasses （BMGs） provides more alloy compositions, large geometric size and diverse mechanical behaviors for some fundamental issues such as deformation and fracture mechanisms of glassy materials and potentiates possibly great applications. In particular, the BMG-s exhibit many unique mechanical properties, such as superior strength and hardness, excellent scratch and wear resistance, extremely high elastic limit, and diverse fracture toughness （varying significantly from approaching ideal brittleness like the oxide glasses for Mg-based BMGs to the highest known damage tolerance for Pd-based BMGs） and patterns （such as dimple structures, nanoscale periodic corrugations, and fiver patterns）. It has become possible to experimentally characterize the mechanical behaviors of metallic glasses and to explore their correlations with the processing conditions, structures and other properties, and accordingly in a more general sense, to understand the deformation, energy dissipation, and fracture mechanisms in the disordered glassy materials. The important and interesting mechanical properties and deformation mechanisms are currently the focus of intense research in the material science community, and the corresponding studies on them are progressing at a fast pace.

关键词： BMGs Foreword

Modified Block Iterative Method for Solving Convex Feasibility Problem, Equilibrium Problems and Variational Inequality Problems

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Acta Mathematica Sinica,English Series 2012年第4期28卷 741-758页

作者： Shi Sheng zhang Chi Kin ChAN h.w.JOSEPh LEE College of Statistics and Mathematics Yunnan Uniersity of Finance and Economics Department of Applied Mathematics The Hong Kong Polytechnic University

The purpose of this paper is by using the modified block iterative method to propose an algorithm for finding a common element in the intersection of the set of common fixed points of an infinite family of quasi-C-asymptotically nonexpansive and the set of solutions to an equilibrium problem and the set of solutions to a variational inequality. Under suitable conditions some strong convergence theorems are established in 2-uniformly convex and uniformly smooth Banach spaces. As applications we utilize the results presented in the paper to solving the convex feasibility problem （CFP） and zero point problem of maximal monotone mappings in Banach spaces. The results presented in the paper improve and extend the corresponding results announced by many authors.

关键词： Modified block iterative algorithm quasi-φ-asymptotically nonexpansive mapping quasi-φ-nonexpansive mapping relatively nonexpansive mapping generalized projection

EFFECT OF TOOL wEAR ON MICROSTRUCTURE, MEChANICAL PROPERTIES AND ACOUSTIC EMISSION OF FRICTION STIR wELDED 6061 Al ALLOY

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Acta Metallurgica Sinica(English Letters) 2006年第1期19卷 9-19页

作者： w.M. Zeng h.L. wu J. zhang East China University of Science and Technology Shanghai 200237 China The University of Texas at El Paso-MetaUurgy and Materials Engineering Texas 79902 USA

Tool condition is one of the main concerns in friction stir welding （FSw）, because the geometrical condition of the tool pin including size and shape is strongly connected to the microstrueture and mechanical performance of the weld. Tool wear occurs during FSw, especially for welding metal matrix composites with large amounts of abrasive particles, and high melting point materials, which significantly expedite tool wear and deteriorate the mechanical performance of welds. Tools with different pin-wear levels are used to weld 6061 Al alloy, while acoustic emission （AE） sensing, metallographic sectioning, and tensile testing are employed to evaluate the weld quality in various tool wear conditions. Structural characterization sh.w. that the tool wear interferes with the weld quality and accounts for the formation of voids in the nugget zone. Tensile test analysis of samples verifies that both the ultimate tensile strength and the yield strength are adversely affected by the formation of voids in the nugget due to the tool wear. The failure location during tensile test clearly depends on the state of the tool wear, which led to the analysis of the relationships between the structure of the nugget and tool wear. AE signatures recorded during welding reveal that the AE hits concentrate on the higher amplitudes with increasing tool wear. The results sh.w.that the AE sensing provides a potentially effective method for the on-line manitoring of tool wear.

关键词： acoustic emission online monitoring tool wear 6061 Al alloy