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Study on first caving fracture mechanism of overlying roof rock in steep thick coal seam

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International Journal of Mining Science and Technology 2015年第1期25卷 133-138页

作者： zhang bei Cao Shenggen State Key Laboratory of Coal Resources and Safe Mining China University of Mining and Technology Shanxi Provincial Guoxin Energy Development Group Co. Ltd.

Based on the elastic plate theory, a mechanical model of thin plate for the first caving of overlying roof rock in steep mining face was established. The analytical solution of the deflection and stress distribution of roof rocks was obtained. According to the specific geological conditions of the 5-103 panel in Shanxi,the failure of roof rocks and the influence of seam dip on it during the exploitation were theoretically investigated. Meanwhile, the first caving characteristics of the overlying rock in the steep coal seam were investigated based on its stress contour. The results show that the dip angle has a distinct influence on the caving interval and the first caving interval for the 5-103 panel is 37 m in theory. Finally, a systematic monitoring on the behavior of rock pressures was conducted. The measured results agree well with the theoretical prediction, which provides a good reference for practical steep coal seam mining.

关键词： SteepMining fieldInitial fracture intervalThin plate theoryCoal pressure monitoring

Mesoscale Predictability of Moist Baroclinic Waves: Variable and Scale-dependent Error Growth

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Advances in Atmospheric Sciences 2014年第5期31卷 995-1008页

作者： bei Naifang Fuqing zhang School of Human Settlements and Civil Engineering Xi'an Jiaotong University Department of Meteorology the Pennsylvanian State University University ParkPennsylvania 16802 USA

This study seeks to quantify the predictability of different forecast variables at various scales through spectral analysis of the difference between perturbed and unperturbed cloud-permitting simulations of idealized moist baroclinic waves amplify- ing in a conditionally unstable atmosphere. The error growth of a forecast variable is found to be strongly associated with its reference-state （unperturbed） power spectrum and slope, which differ significantly from variable to variable. The shallower the reference state spectrum, the more spectral energy resides at smaller scales, and thus the less predictable the variable since the error grows faster at smaller scales before it saturates. In general, the variables with more small-scale components （such as vertical velocity） are less predictable, and vice versa （such as pressure）. In higher-resolution simulations in which more rigorous small-scale instabilities become better resolved, the error grows faster at smaller scales and spreads to larger scales more quickly before the error saturates at those small scales during the first few hours of the forecast. Based on the reference power spectrum, an index on the degree of lack （or loss） of predictability （LPI） is further defined to quantify the predictive time scale of each forecast variable. Future studies are needed to investigate the scale- and variable-dependent predictability under different background reference flows, including real case studies through ensemble experiments.

关键词： predictability baroclinic waves error growth mesoscale

Crushing Behaviors of Frac tai Hexagonal Tubular Structures: Experiments and Plastic Analysis

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Acta Mechanica Solida Sinica 2019年第6期32卷 713-724页

作者： Weiwei Li bei zhang Hualin Fan Research Center of Lightweight Structures and Intelligent Manufacturing State Key Laboratory of Mechanics and Control of Mechanical StructuresNanjing University of Aeronautics and AstronauticsNanjing 210016China State Key Laboratory for Disaster Prevention&Mitigation of Explosion&Impact PLA Army Engineering UniversityNanjing 210007China Department of Civil Engineering Nanyang Institute of TechnologyNanyang 473004China Research Institute for National Defense Engineering of Academy of Military Science PLA Luoyang 471023China

Fractal tubular structures(FTSs)can greatly increase the anti-crushing and energy absorption capacity of the *** reveal this mechanism,fractal hexagonal tubes(FHTs)with self-similar fractal structure were designed and *** experiments were carried out to verify the crushing modes of structures with different scale *** with the single-cell structure,FHTs have much greater mean crushing force(MCF).According to the experiments and the numerical simulations,when the side length of the second-order hexagon is 0.3 times of the length of the first-order primary hexagon,the FTS has the greatest peak force(PF)and MCF as well as the most excellent energy-absorbing *** folding styles were revealed by the experiments and the numerical simulation when changing the scale factor,including the overall folding mode,the local foaling mode and the hybrid folding *** plastic models were built,which consistently predicted the MCF.

关键词： Fractal structure Crushing Energy absorption Plastic analysis

Mechanical effects of circular liquid inclusions inside soft matrix:role of internal pressure change and surface tension

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Applied Mathematics and Mechanics(English Edition) 2021年第4期42卷 501-510页

作者： lei zhang College of Mechanical and Vehicle Engineering Chongqing UniversityChongqing 400044China

The mechanical effects of dilute liquid inclusions on the solid-liquid composite are explored,based on an analytical circular inclusion model incorporating the internal pressure change of the liquid and the surface tension of the *** simple explicit dependences of the stress field and effective stiffness on the bulk modulus and the size of the liquid,the surface tension,and Poisson’s ratio of the matrix are *** results show that the stresses in the matrix are reduced,and the stiffness of the solid-liquid composite is enhanced with the consideration of either the surface tension or the internal pressure ***,the effective Young’s modulus predicted by the present model for either soft or stiff matrices agrees well with the known experimental *** addition,according to the theoretical results,it is possible to stiffen a soft solid by pressured gas with the presence of the surface tension of the solid-gas interface.

关键词： liquid inclusion stress field effective stiffness surface tension internal pressure change

有限元分析不同内固定方式治疗肱骨近端骨折的力学差异

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中国组织工程研究 2025年第15期29卷 3101-3109页

作者：王磊王清张申申福建医科大学附属闽东医院福建省福安市355000 福建医科大学福建省福州市350108

背景:目前临床中治疗肱骨近端骨折的钢板内固定方式仍无绝对标准,但重建内侧肱骨距并有效抵抗肱骨头内翻移位是实现肱骨近端骨折坚强固定的要点。目的:利用有限元分析技术获得3种内固定方式作用于肱骨近端骨折的力学差异,对比何种内固... 详细信息

背景:目前临床中治疗肱骨近端骨折的钢板内固定方式仍无绝对标准,但重建内侧肱骨距并有效抵抗肱骨头内翻移位是实现肱骨近端骨折坚强固定的要点。目的:利用有限元分析技术获得3种内固定方式作用于肱骨近端骨折的力学差异,对比何种内固定方法可以提供更加稳定的固定支撑。方法:选择一名健康女性志愿者进行左肩关节的CT扫描,通过有限元分析软件构建肱骨近端骨折伴内侧柱支撑缺损模型。根据钢板内固定方式将模型划分为3组:A组仅在外侧应用Philos钢板固定;B组外侧应用Philos钢板联合内侧微型直行锁定加压板固定;C组外侧Philos钢板联合前内侧微型直行锁定加压板固定。在相同的固定支撑和约束条件下,采用ANSYS分析软件评估3组内固定模型的生物力学稳定性。结果与结论:①3组内固定模型的内固定物应力均未超过450 MPa;②不同载荷条件下,A组肱骨和内固定物的应力较高于B、C两组,而C组的肱骨和内固定物的应力均为最小值;③在屈曲载荷条件下,C组的相对位移对比A、B两组数值较小;④所有载荷条件下,B组的骨折端相对位移是最小的;在内收、外展以及轴向压缩的载荷条件下,B组的相对位移大约只有A组的一半;⑤C组与B组之间的相对位移并没有显著的差异,且C组的相对位移也均小于A组;⑥结果发现,相较于仅应用外侧Philos钢板,外侧Philos钢板与内侧微型直行锁定加压板的联合应用,以及外侧Philos钢板与前内侧微型直行锁定加压板的联合应用,均展现出显著的内固定系统稳定性,后两种组合在内固定系统稳定性上并未呈现出明显差异;综合考虑临床实践中的操作难易程度,外侧Philos钢板与前内侧微型直行锁定加压板的联合内固定方式治疗肱骨近端骨折可能更具优势。

关键词：肱骨近端骨折内侧柱重建 Philos钢板双钢板有限元分析

Joint Power Allocation and Mode Selection for D2D Communications with Imperfect CSI

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China Communications 2015年第7期12卷 73-81页

作者： MA bei zhang Hailin zhang Zhaowei Broadband Wireless Communications Laboratory Information Science InstituteState Key Laboratory of Integrated Service NetworksXidian University

Device-to-device(D2D) communications can be underlaid with a cellular infrastructure to increase resource utilization, improve user throughput and save battery energy. In such networks, power allocation and mode selection are crucial problems. To address the joint optimization of power and mode selection under imperfect CSI, we propose an optimal, energy-aware joint power allocation and mode selection(JPAMS) scheme. First, we derive the closed-form solution for the power minimization for both D2 D and cellular links while satisfying different quality of service(Qo S) constraints. Second, we address the mode selection problem in presence of imperfect CSI, based on the derived power allocation. Moreover, the theoretical analysis and simulation results are presented to evaluate the proposed scheme for the D2 D communications.

关键词： power allocation mode selection D2D communications imperfect CSI energy-aware

Depression mechanism of sulfite ions on sphalerite and Pb^(2+)activated sphalerite in the flotation separation of galena from sphalerite

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International Journal of Minerals,Metallurgy and Materials 2025年第2期32卷 335-345页

作者： Feng zhang Chenyang zhang Linlin Wu Wei Sun Hongliang zhang Jianhua Chen Yong Pei Songjiang Li Engineering Research Center of Ministry of Education for Carbon Emission Reduction in Metal Resource Exploitation and Utilization Hunan International Joint Research Center for Efficient and Clean Utilization of Critical Metal Mineral ResourcesSchool of Minerals Processing and BioengineeringCentral South UniversityChangsha 410083China State Key Laboratory of Mineral Processing Beijing General Research Institute of Mining&MetallurgyBeijing 100160China Hunan Provincial Key Laboratory of Micro&Nano Materials Interfaces Science College of Chemistry and Chemical EngineeringCentral South UniversityChangsha 410083China School of Resources Environment and MaterialsGuangxi UniversityNanning 530004China Department of Chemistry Xiangtan UniversityXiangtan 411105China China Railway Resource Group Co.Ltd Beijing 102300China

The depression mechanism of sulfite ions on sphalerite and Pb^(2+)activated sphalerite in the flotation separation of galena from sphalerite still lacked in-depth ***,the depression mechanism of sulfite ions on sphalerite and Pb^(2+)activated sphalerite in the flotation separation of galena from sphalerite was further systematically investigated with experiments and density functional theory(DFT)*** X-ray photoelectric spectroscopy(XPS)results,DFT calculation results,and frontier molecular orbital analysis indicated that sulfite ions were difficult to be adsorbed on sphalerite surface,suggesting that sulfite ions achieved depression effects on sphalerite through other non-adsorption ***,the oxygen content in the surface of sphalerite treated with sulfite ions in creased,which enhanced the hydrophilicity of the sphalerite and further increased the difference in hydrophilicity between sphalerite and ***,sulfite ions were chelated with lead ions to form PbSO_(3)in *** hydrophilic PbSO_(3)was more easily adsorbed on sphalerite than *** interaction between sulfite ions and lead ions could effectively inhibit the activation of *** addition the UV spectrum showed that after adding sulfite ions,the peak of perxanthate in the sphalerite treated xanthate solution was significantly stronger than that in the galena with xanthate solution,indicating that xanthate interacted more readily with sulfite ions and oxygen mo lecules within the sphalerite system,leading to the formation of ***,sulfite ions hardly depressed the flotation of ga lena and could promote the flotation of galena to some *** study deepened the understanding of the depression mechanism o sulfite ions on sphalerite and Pb^(2+)activated sphalerite.

关键词： sphalerite galena sulfite ion density functional theory depression mechanism

Cryptococcus infection with asymptomatic diffuse pulmonary disease in an immunocompetent patient:A case report

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World Journal of Clinical Cases 2021年第11期9卷 2619-2626页

作者： Yong Li lei Fang Fang-Qun Chang Fang-Zhou Xu Yan-bei zhang Department of Geriatric Respiratory and Critical Care The First Affiliated Hospital of Anhui Medical UniversityHefei 230000Anhui ProvinceChina Department of Tuberculosis Anhui Medical University Clinical College of Chest&Anhui Chest HospitalHefei 230000Anhui ProvinceChina

BACKGROUND Cryptococcus presenting as an opportunistic pathogen mainly affects immunocompromised patients,but the disseminated form of infection is rare among immunocompetent *** partial radiographic characteristics of pulmonary cryptococcosis mimic lung carcinoma,leading to unnecessary open chest exploratory surgery,and the lack of a gold-standard noninvasive diagnostic increases the risk of *** emission tomography/computed tomography(PET/CT),a sensitive method for distinguishing malignant tumors,coupled with cryptococcal latex agglutination test showing a high positive rate may overcome these *** A 36-year-old man presented for general examination,without health *** CT showed multiple pulmonary nodules and a mass with high maximum standardized uptake ***,we suspected primary malignancy with hematogenous *** his routine fungal analysis had been negative,subsequent CT-guided percutaneous core needle biopsy and histopathology examination indicated a diagnosis of pulmonary ***(200 mg/d)antifungal drug treatment was initiated,and 1 mo later the pulmonary mass had reduced in size markedly(on chest CT scan)without any *** Serologic and PET/CT examinations may not rule out cryptococcosis,and percutaneous lung puncture is critical under all circumstances.

关键词： Cryptococcus Immunocompetent Positron emission tomography Computed tomography Cryptococcal latex agglutination test Lung diseases Fungal Case report

金属二聚体和氮共掺杂石墨烯(Gra)M_(2)N_(6)-Gra(M=Cr-Cu)的NO_(2)吸附特性理论研究

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原子与分子物理学报 2025年第5期42卷 35-42页

作者：张展博余娇魏亚茹张轩靳鑫张子音杨保成张雷雷黄河科技学院纳米功能材料研究所郑州450063

NO_(2)是空气污染物的主要成分之一,设计和开发高效的气敏传感器对NO_(2)进行检测具有重要意义.本工作利用基于密度泛函理论(DFT)的第一性原理计算方法对不同过渡金属原子形成的金属二聚体和氮共掺杂石墨烯(Gra)M_(2)N_(6)-Gra(M=Cr-Cu)... 详细信息

NO_(2)是空气污染物的主要成分之一,设计和开发高效的气敏传感器对NO_(2)进行检测具有重要意义.本工作利用基于密度泛函理论(DFT)的第一性原理计算方法对不同过渡金属原子形成的金属二聚体和氮共掺杂石墨烯(Gra)M_(2)N_(6)-Gra(M=Cr-Cu)的NO_(2)吸附特性进行了研究.结果表明,NO_(2)分子与M_(2)N_(6)-Gra之间均存在明显的化学吸附作用.其中,Ni_(2)N_(6)-Gra和Cu_(2)N_(6)-Gra体系具备较为适中的恢复时间(分别约为5秒和14分钟),这意味着这两个体系是开发新型NO_(2)气敏材料的潜在候选者.其它体系(M_(2)N_(6)-Gra,M=Cr-Co)强的吸附作用导致恢复时间过长,从而使得它们不适合作为NO_(2)气敏材料.这一研究不仅有望为设计和开发性能优异的新型NO_(2)气敏材料提供有益理论指导,还将有益于人们深入认识M_(2)N_(6)-Gra材料的NO_(2)电催化合成NO或NH 3性能.

关键词： M_(2)N_(6)-Gra NO_(2)吸附密度泛函理论