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The rock breaking and ROP increase mechanisms for single-tooth torsional impact cutting using DEM

Petroleum Science 2019年第5期16卷 1134-1147页

作者： Xiao-Hua Zhu Yun-Xu Luo wei-ji liu School of Mechatronic Engineering Southwest Petroleum UniversityChengdu 610500China Postdoctoral Research Station for Oil and Gas Engineering Southwest Petroleum UniversityChengdu 610500China

Torsional impact drilling is a new technology which has the advantages of high rock-breaking efficiency and a high rate of penetration(ROP).So far,there is no in-depth understanding of the rock-breaking mechanism for the ROP increase from torsional impact ***,it has practical engineering significance to study the rock-breaking mechanism of torsional *** this paper,discrete element method(DEM)software(PFC2 D)is used to compare granite breaking under the steady and torsional impacting ***,the energy consumption to break rock,microscopic crushing process and chip characteristics as well as the relationship among these three factors for granite under different impacting frequencies and amplitudes are *** is found that the average cutting force is smaller in the case of torsional impact cutting(TIC)than that in the case of steady *** mechanical specific energy(MSE)and the ratio of brittle energy consumption to total energy are negatively correlated;rock-breaking efficiency is related to the mode of action between the cutting tooth and ***,the ROP increase mechanism of torsional impact drilling technology is that the ratio of brittle energy consumption under the TIC condition is larger than that under a steady load;the degree of repeated fragmentation of rock chips under the TIC condition is lower than that under the steady load,and the TIC load promotes the formation of a transverse cracking network near the free surface and inhibits the formation of a deep longitudinal cracking network.

关键词： Torsional impact rock breaking Mechanical specific energy Fractal dimension Microcrack DEM

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Risk analysis for aspirin and postoperative intracranial hemorrhage- report of 3 cases

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Chinese Medical Journal 2009年第10期122卷 1231-1233页

作者： YU Shu-qing WANG ji-sheng ji Nan liu wei QIAN Ke Department of Neurosurgery Beijing Tiantan Hospital Capital Medical University Beijing 100050 China

Aspirin has been widely used clinically since 1899. For patients with cerebral ischemia and implanted intravascular stents, aspirin has been used routinely prevention of intracranial hemorrhage and for for anticoagula... 详细信息

关键词： aspirin postoperative intracranial hemorrhage

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Clinical characteristics and therapeutic strategies of atypical meningioma

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Chinese Medical Journal 2011年第7期124卷 1094-1096页

作者： YU Shu-qing WANG ji-sheng ji Nan liu wei QIAN Ke Department of Neurosurgery Beijing Tiantan Hospital Capital Medical University Beijing 100050 China

Background Atypical meningioma accounts for about 4.7% to 7.2% of all kinds of meningiomas, which is invasive with a relatively high recurrence and mortality. The objective of this study was to investigate the clinica... 详细信息

关键词： atypical meningioma characteristics therapeutic strategies

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Micro-macro fracture mechanism of heterogeneous granite in percussive drilling

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Petroleum Science 2023年第5期20卷 3131-3142页

作者： wei-ji liu Yan-Fei Wang Zhao-Wang Dan Xiao-Hua Zhu School of Mechatronic Engineering Southwest Petroleum UniversityChengdu610500SichuanChina Geothermal Energy Research Center Southwest Petroleum UniversityChengdu610500SichuanChina Powerchina Sinohydro Bureau 7 Co. LTDChengdu610500SichuanChina

The conventional rotary rock breaking method faces a technical bottleneck in improving the rate of penetration(ROP)in deep hard *** drilling is the most potential approach to increase rock-breaking efficiency and ***,the rock-breaking mechanism of percussive drilling is still unclear enough,especially the micro-fracture mechanism of rock under confining pressure(under lateral pressure and hydraulic pressure).In this paper,the impact rock breaking experiments by four kinds of Polycrystalline Diamond Compact(PDC)cutters are carried out using a drop-weight impact testing machine and an acoustic emission(AE)recording system,the influence of parameters such as cutter shape,rake angle,and impact energy on rock-breaking are systematically *** study includes a numerical simulation to examine the process of crack initiation,propagation,and cuttings formation during the impact process with the consideration of confining *** results show the conicalshaped cutter is the most aggressive with high breaking *** penetration depth of the cutter is mainly influenced by the impact energy and cutter shape than the rake angle of the *** exists critical impact energy makes the rock breaking efficiency the *** critical impact energy is about 40 J when using the conical-shaped cutter with a rake angle of 15°.The rock mainly failed in tensile mode,and the inter-grain crack is the main *** pressure can inhibit the formation of horizontal cracks,while lateral pressure can inhibit the formation of vertical cracks and reduce the proportion of tensile *** research results can provide some reference and basis for improving the rock-breaking efficiency in deep hard formations.

关键词： Percussive drilling PFC Rock fragmentation characteristics Rock breaking efficiency

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A reweighted damped singular spectrum analysis method for robust seismic noise suppression

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Petroleum Science 2024年第3期21卷 1671-1682页

作者： wei-Lin Huang Yan-Xin Zhou Yang Zhou wei-jie liu ji-Dong Li State Key Laboratory of Petroleum Resources and Engineering China University of Petroleum(Beijing)Beijing2249China SINOPEC Petroleum Exploration and Production Research Institute Beijing102206China SINOPEC Geophysical Research Institute Nanjing211103jiangsuChina

(Multichannel)Singular spectrum analysis is considered as one of the most effective methods for seismic incoherent noise *** utilizes the low-rank feature of seismic signal and regards the noise suppression as a low-rank reconstruction ***,in some cases the seismic geophones receive some erratic disturbances and the amplitudes are dramatically larger than other *** presence of this kind of noise,called erratic noise,makes singular spectrum analysis(SSA)reconstruction unstable and has undesirable effects on the final *** robustify the low-rank reconstruction of seismic data by a reweighted damped SSA(RD-SSA)*** incorporates the damped SSA,an improved version of SSA,into a reweighted *** damping operator is used to weaken the artificial disturbance introduced by the low-rank projection of both erratic and random *** central idea of the RD-SSA method is to iteratively approximate the observed data with the quadratic norm for the first iteration and the Tukeys bisquare norm for the rest *** RD-SSA method can suppress seismic incoherent noise and keep the reconstruction process robust to the erratic *** feasibility of RD-SSA is validated via both synthetic and field data examples.

关键词： Singular spectrum analysis Damping operator Seismic erratic noise Seismic signal processing Robust low-rank reconstruction

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Chalcogen-dependent catalytic properties of RuX2 (X = S/Se/Te) nanoparticles decorated carbon nanofibers for hydrogen evolution in acidic and alkaline media

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Nano Research 2024年第4期17卷 2528-2537页

作者： Chengkai He Yue wei jia Xu Yujie wei Tao Wang Rongfei liu Lvlv ji Zhun liu Sheng Wang School of Materials Science and Engineering Zhejiang Sci-Tech UniversityHangzhou 310018China Department of Physics Shaoxing UniversityShaoxing 312000China Zhejiang Kangjiesi New Material Technology Co. LTDZhuji 311800China

Transition metal dichalcogenides(TMDs),with the general formula MX_(2)(M=Mo/W/Fe/Co/Ni,etc.;X=S/Se/Te),have attracted extensive research interests for hydrogen evolution reaction(HER).Compared with numerous studies on noble-metal-free TMDs,the chalcogen-dependent HER catalytic properties of noble-metal-based TMDs are lack of sufficient research ***,a facile electrospinning-assisted synthetic strategy is proposed to synthesize ruthenium dichalcogenides(RuX_(2),X=S/Se/Te)nanoparticles decorated carbon nanofibers(CNFs).Benefiting from the identical nanofibrous morphology and exposed crystal planes of RuX_(2)(111),the catalytic activities of RuX_(2)@CNFs samples were investigated and compared in a fair and direct *** electrochemical measurements coupled with density functional theory calculations were carried out to probe their intrinsic HER catalytic activities,resulting in the catalytic activity order of RuS_(2)@CNFs>RuSe_(2)@CNFs>RuTe_(2)@CNFs in acidic media and that of RuS_(2)@CNFs>RuTe_(2)@CNFs>RuSe_(2)@CNFs in alkaline *** superior catalytic performance of RuS_(2)@CNFs mainly stems from the relative lower HER energy barriers and thereby the higher intrinsic catalytic activity of RuS_(2)(111),leading to ultralow overpotentials of 44 and 9 mV at 10 mA·cm^(-2) in acidic and alkaline media,***_(2)(111)is endowed with the more optimized Gibbs free energy of hydrogen adsorption(ΔGH*)than RuTe_(2)(111),but RuTe_(2)(111)shows enhanced catalytic property for H_(2)O dissociation and OH-desorption than RuSe_(2)(111),therefore,resulting in the altered catalytic activity sequences for RuSe_(2) and RuTe_(2) in acidic and alkaline media.

关键词： hydrogen evolution reaction transition metal dichalcogenides carbon nanofibers electrocatalysis catalytic activity

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Temperature-dependent photoluminescence of highly luminescent water-soluble CdTe quantum dots

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Chinese Chemical Letters 2009年第8期20卷 977-980页

作者： ji wei liu Yu Zhang Cun Wang Ge Yong Long jin Sun Ling Hu Ning Gu State Key Laboratory of Bioelectronics Jiangsu Key Laboratory for Biomaterials and Devices Southeast University Nanjing 210096 China School of Chemistry and Chemical Engineering Southeast University Nanjing 210096 China Department of Chemistry Nantong University Nantong 226007 China

Highly luminescent water-soluble CdTe quantum dots （QDs） have been synthesized with an electrogenerated precursor. The obtained CdTe QDs can possess good crystallizability, high quantum yield （QY） and favorable stability. Furthermore, a detection system is designed firstly for the investigation of the temperature-dependent PL of the QDs. ？2009 Yu Zhang. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

关键词： Quantum dots Temperature-dependent photoluminescence Fluorescent detection

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Defects in the grain interiors of 3 mol%yttria-stabilized tetragonal zirconia polycrystal ceramics with 0.25 wt%alumina

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Journal of Advanced Ceramics 2024年第4期13卷 469-477页

作者： Yan Xiong Lian Luo Yao Cheng Zhi liu Qi liu weimin Wang wei ji School of Materials&Chemical Engineering Hubei Province Key Laboratory of Green Materials for Light IndustryHubei University of TechnologyWuhan 430068China Fujian Institute of Research on the Structure of Mater Chinese Academy of SciencesFuzhou 350002China jiangxi Provincial Engineering Research Center for Multifunction Zirconia Materials Jiangxi Size Materials Co.Ltd.Jiujiang 332500China State Key Laboratory of Advance Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China

The presence of high-density defects is rarely observed in bulk 3 mol%yttria-stabilized tetragonal zirconia polycrystal(3Y-TZP)ceramics obtained through conventional pressureless *** the present work,fine-grained dense 147 nm 3Y-TZP ceramics were prepared by pressureless sintering of commercial 0.25 wt%alumina-doped zirconia powders at 1300℃.A novel discovery was reported in which large amounts of defects were present in the grain interiors of the *** phenomenon was further examined using three types of powder samples,and the reasons for defect formation were investigated by microstructural characterization using high-resolution transmission electron microscopy(HRTEM)analysis and Rietveld *** results confirmed the essential dependence of the defect formation on the alumina *** authors attributed the defect formation to the significant difference in ionic radii of the solvent and solute during the dissolution of alumina into the zirconia *** sintering kinetics were proposed to be enhanced by the presence of substantial defects,which consequently favored the low-temperature sintering of the alumina-doped zirconia ceramics.

关键词： 3 mol%yttria-stabilized tetragonal zirconia polycrystal(3Y-TzP)ceramics alumina addition microstructure defect

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Single-cluster electronics using metallic clusters:Fabrications,regulations,and applications

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Nano Research 2024年第1期17卷 65-78页

作者： Caiyun wei wei Xu Shurui ji Ruiyun Huang Junyang liu Wenqiu Su jie Bai jiale Huang Wenjing Hong State Key Laboratory of Physical Chemistry of Solid Surfaces National Engineering Research Centre of Chemicals for Electronic ManufacturingCollege of Chemistry and Chemical Engineering&Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province(IKKEM)Xiamen UniversityXiamen 361005China

Metallic clusters,ranging from 1 to 2 nm in size,have emerged as promising candidates for creating nanoelectronic devices at the single-cluster *** the intermediate quantum properties between metals and semiconductors,these metallic clusters offer an alternative pathway to silicon-based electronics and organic molecules for miniaturized electronics with dimensions below 5 *** progress has been made in studies of single-cluster electronic ***,a clear guide for selecting,synthesizing,and fabricating functional single-cluster electronic devices is still *** review article provides a comprehensive overview of single-cluster electronic devices,including the mechanisms of electron transport,the fabrication of devices,and the regulations of electron transport ***,we discuss the challenges and future directions for single-cluster electronic devices and their potential applications.

关键词： single-cluster junctions electronic properties electron transport metallic clusters structure regulation

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Soft coarse-grained particle model for particle-fluid systems

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Particuology 2024年第1期84卷 178-193页

作者： Yanhao Ye ji Xu wei Ge State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of SciencesBeijing100190China School of Chemical Engineering University of Chinese Academy of SciencesBeijing100049China Innovation Academy for Green Manufacture Chinese Academy of SciencesBeijing100190China

By modeling a group of neighboring real particles as a single coarse-grained particle(CGP),discrete particle method(DPM)is now capable of simulating industrial-scale particle-fluid ***,a systematic approach to determine the CGP properties and develop their interaction models is still lacking,which casts uncertainty on the predictivity of the *** this study,collisions between predefined particle groups are analyzed to construct kernel functions for modeling the CGPs and then the model parameters are determined by equating the statistical properties of the CGPs and the real particles in the physical process *** approach is implemented for homogeneous cooling of granular gas,then demonstrated effective in simulating experimental fluidized beds.

关键词： Coarse-grain(CG) Discrete particle method(DPM) Fluidized bed Multi-scale simulation

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