检索结果-南通市图书馆

Three-dimensional pseudo-dynamic reliability analysis of seismic shield tunnel faces combined with sparse polynomial chaos expansion

在线全文

学校读者我要写书评

暂无评论

Journal of Central South University 2024年第6期31卷 2087-2101页

作者： GUO feng-qi LI Shi-wei ZOU jin-feng School of Civil Engineering Central South UniversityChangsha 410075China

To address the seismic face stability challenges encountered in urban and subsea tunnel construction,an efficient probabilistic analysis framework for shield tunnel faces under seismic conditions is *** on the upper-bound theory of limit analysis,an improved three-dimensional discrete deterministic mechanism,accounting for the heterogeneous nature of soil media,is formulated to evaluate seismic face *** metamodel of failure probabilistic assessments for seismic tunnel faces is constructed by integrating the sparse polynomial chaos expansion method(SPCE)with the modified pseudo-dynamic approach(MPD).The improved deterministic model is validated by comparing with published literature and numerical simulations results,and the SPCE-MPD metamodel is examined with the traditional MCS *** on the SPCE-MPD metamodels,the seismic effects on face failure probability and reliability index are presented and the global sensitivity analysis(GSA)is involved to reflect the influence order of seismic action ***,the proposed approach is tested to be effective by a engineering case of the Chengdu outer ring *** results show that higher uncertainty of seismic response on face stability should be noticed in areas with intense earthquakes and variation of seismic wave velocity has the most profound influence on tunnel face stability.

关键词： reliability analysis shield tunnel face sparse polynomial chaos expansion modified pseudo-dynamic approach seismic stability assessment

Evolution of In783 alloy in microstructure and properties enduring different service times

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2024年第1期43卷 334-341页

作者： Zhong-Shuai Han jin-feng Du Jun Liang Zheng Zhang School of Material Science and Engineering Beihang UniversityBeijing 100191China Shenhua Guohua(Beijing)Electric Power Research Institute Co. Ltd.Beijing 100025China

Impact, tensile, and fatigue tests were performed in In783 alloy serving 4000, 23,000 and 48,000 h. The microstructure was then analysed by optical microscopy(OM), scanning electron microscopy(SEM), and transmission electron microscopy(TEM) to probe the relationship between microstructure and properties. The results show that a new Ni_(5)Al_(3) phase is found, which grows gradually in β phase with serving time increasing,destroying the martensitic structure of the β phase, and degenerating the toughness of the β phase(approximately13.88% reduction). Therefore, the degradation of the βphase results in a sharp dropping of the resistance to stress accelerated grain boundary oxygen(SAGBO) during serving;thus, the intergranular fracture morphology degree increases with duration of service(almost 40% increase from the fractured surface). In addition, the strength of alloy will be gradually enhanced when the γ'phase becomes relatively bulky with serving time increasing due to considerable distortion of the dislocations as a result of the spacing of individual particles, in which any movement of the dislocation will have to overcome a larger number of obstacles per unit length.

关键词： In783 Microstructure Properties βphase Ni_(5)Al_(3)phase

Exploration on electrical resistance tomography in characterizing the slurry spatial distribution in cemented granular materials

在线全文

学校读者我要写书评

暂无评论

Frontiers of Structural and Civil Engineering 2024年第3期18卷 365-379页

作者： Bohao WANG Wei WANG feng jin Handong TAN Ning LIU Duruo HUANG State Key Laboratory of Hydroscience and Engineering Tsinghua UniversityBeijing 100084China Institute of Science and Technology China Three Gorges CorporationBeijing 100038China School of Geophysics and Information Technology China University of GeosciencesBeijing 100083China

This study investigated the application of electrical resistance tomography(ERT)in characterizing the slurry spatial distribution in cemented granular materials(CGMs).For CGM formed by self-flow grouting,the voids in the accumulation are only partially filled and the bond strength is often limited,which results in difficulty in obtaining in situ samples for quality ***,it is usually infeasible to evaluate the grouting effect or monitor the slurry spatial distribution by a mechanical *** this research,the process of grouting cement paste into high alumina ceramic beads(HACB)accumulation is reliably monitored with *** shows that ERT results can be used to calculate the cement paste volume in the HACB accumulation,based on calibrating the saturation exponent n in Archie’s *** results support the feasibility of ERT as an imaging tool in CGM characterization and may provide guidance for engineering applications in the future.

关键词： electrical resistance tomography cemented granular material grouting spatial distribution Archie’s law

A real-time intelligent lithology identification method based on a dynamic felling strategy weighted random forest algorithm

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Petroleum Science 2024年第2期21卷 1135-1148页

作者： Tie Yan Rui Xu Shi-Hui Sun Zhao-Kai Hou jin-Yu feng School of Petroleum Engineering Northeast Petroleum UniversityDaqing163318HeilongjiangChina Sanya Offshore Oil&Gas Research Institute Northeast Petroleum UniversitySanya572025HainanChina

Real-time intelligent lithology identification while drilling is vital to realizing downhole closed-loop drilling. The complex and changeable geological environment in the drilling makes lithology identification face many challenges. This paper studies the problems of difficult feature information extraction,low precision of thin-layer identification and limited applicability of the model in intelligent lithologic identification. The author tries to improve the comprehensive performance of the lithology identification model from three aspects: data feature extraction, class balance, and model design. A new real-time intelligent lithology identification model of dynamic felling strategy weighted random forest algorithm(DFW-RF) is proposed. According to the feature selection results, gamma ray and 2 MHz phase resistivity are the logging while drilling(LWD) parameters that significantly influence lithology identification. The comprehensive performance of the DFW-RF lithology identification model has been verified in the application of 3 wells in different areas. By comparing the prediction results of five typical lithology identification algorithms, the DFW-RF model has a higher lithology identification accuracy rate and F1 score. This model improves the identification accuracy of thin-layer lithology and is effective and feasible in different geological environments. The DFW-RF model plays a truly efficient role in the realtime intelligent identification of lithologic information in closed-loop drilling and has greater applicability, which is worthy of being widely used in logging interpretation.

关键词： Intelligent drilling Closed-loop drilling Lithology identification Random forest algorithm Feature extraction

Microstructural Evolutions and Mechanical Properties of Energetic Al_(1) (TiZrNbTaMoCr)_(15) High-Entropy Alloys

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2024年第4期37卷 620-632页

作者： Xuan-Hong Cai Zhen-Hua Wang Ben Niu jin-feng Li Qing Wang Show authors Key Laboratory of Materials Modification By Laser Ion and Electron Beams(Ministry of Education)Engineering Research Center of High Entropy Alloy Materials(Liaoning Province)School of Materials Science and EngineeringDalian University of TechnologyDalian116024China Institute of Materials China Academy of Engineering PhysicsMianyang621908China

The present study focuses on investigating the microstructural evolutions and mechanical properties of energetic Al_(1)(TiZrNbTaMoCr)_(15) refractory high-entropy alloys with the different heat treatments at low Al content state. It is found that even with a reduction in the Al content, the strength of these alloys remains unaffected at room temperature and high temperature, while the plasticity improves significantly. In particular, the coherent BCC/B_(2) microstructure with needle-like B_(2) nanoprecipitates dispersed into the BCC matrix is formed in 873 K-aged Al_(1)Ti_(6)Zr_(2)Nb_(3)Ta_(3)Mo_(0.5)Cr_(0.5) alloy. Therefore, this alloy exhibits the highest compression yield strength (σ_(YS) = 1333 and 717 MPa) at room temperature and 1073 K, respectively. After 973 K-aged, the coherent BCC/B_(2) microstructure underwent destabilization, and the B_(2) phase transforms into the brittle Zr5Al3 phase which then coarsens and dominates the microstructure of S3-AlTa_(3) alloy after 1073 K-aged. Moreover, these current alloys exhibit exceptionally high theoretical exothermic enthalpy (ΔH), surpassing 11606 J·g^(−1), which highlights their significant potential as innovative high-performance energetic structural materials.

关键词： Refractory high-entropy alloy Coherent microstructure Mechanical property Exothermic enthalpy

Alzheimer's disease with depressive symptoms: Clinical effect of intermittent theta burst stimulation repetitive transcranial magnetic stimulation

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Psychiatry 2024年第8期14卷 1216-1223页

作者： Xin jin Chun-Yun Xu jin-feng Fei Yu Fang Cong-Hao Sun Department of Psychiatry Huzhou Third Municipal HospitalThe Affiliated Hospital of Huzhou UniversityHuzhou 313000Zhejiang ProvinceChina

BACKGROUND Alzheimer's disease(AD),characterized by the ongoing deterioration of neural function,often presents alongside depressive features and greatly affects the quality of life of individuals living with the *** several treatment methods exist,their efficacy is *** recent years,repetitive transcranial magnetic stimulation(rTMS)utilizing the theta burst stimulation(TBS)mode,specifically the intermittent TBS(iTBS),has demonstrated promising therapeutic potential in the management of neuropsychiatric *** To examine the therapeutic efficacy of iTBS mode of rTMS for treating depressive symptoms in patients with *** This retrospective study enrolled 105 individuals diagnosed with AD with depressive symptoms at Huzhou Third Municipal Hospital,affiliated with Huzhou University,between January 2020 and December *** received standard pharmacological interventions and were categorized into control(n=53)and observation(n=52)groups based on treatment *** observation group received iTBS mode of rTMS,while the control group received pseudo-stimulation.A comparative analysis evaluated psychological well-being,adverse events,and therapeutic at initiation of hospitalization(T0)and 15 days post-treatment(T1).RESULTS At T1,both groups exhibited a marked reduction in self-rating depression scale and Hamilton depression scale scores compared to ***,the observa-tion group showed a more pronounced decrease than the control *** T1,the Mini-mental state examination scores for both groups had increased markedly from their initial T0 ***,the increase was particularly more substantial in the observation group than in the control *** patients in the control group had ineffective treatment effects,while five patients in the observation group experienced the ***,the observation group experienced a substantially reduced incidence of ineffective treatment as compared to th

关键词： Alzheimer's disease Non-persistentθshort array fast pulse mode Depression Clinical efficacy Dementia Repetitive transcranial magnetic stimulation

Thoracic spine infection caused by Pseudomonas fluorescens:A case report and review of literature

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Clinical Cases 2024年第12期12卷 2099-2108页

作者： Liang Li Bao-Hua Zhang jin-feng Cao Li-jin Zhang Ling-Ling Guo Department of Traditional Chinese Medicine Zibo Central HospitalZibo 255000Shandong ProvinceChina Department of Pathology Zibo Central HospitalZibo 255000Shandong ProvinceChina Department of Medical Imaging Zibo Central HospitalZibo 255000Shandong ProvinceChina

BACKGROUND The clinical incidence of spinal infection is gradually increasing,and its onset is insidious,easily leading to missed diagnosis and misdiagnosis,which may lead to serious complications such as nervous system dysfunction,spinal instability and/or deformity,and cause a huge burden on society and *** identification of the causative agent and precision medicine will greatly reduce the suffering of *** present,the main pathogenic bacteria that cause spinal infection are Staphylococcus aureus,Streptococcus,Pneumococcus,Escherichia coli,and *** are no reports of spinal infection caused by Pseudomonas *** SUMMARY We report a 32-year-old female patient with spinal *** presented with flank pain,initially thought to be bone metastases or bone tuberculosis,and had a family background of *** clinical features and changes in imaging and laboratory tests led to the suspicion of thoracic spine *** of the lesion showed inflammation,tissue culture of the lesion was negative several times,and the possible pathogen-Pseudomonas fluorescens was found after gene sequencing of the *** patient recovered completely after a full course of antibiotic *** This report increases the range of pathogens involved in spinal infections,highlights the unique advantages of gene sequencing technology in difficult-todiagnose diseases,and validates conservative treatment with a full course of antibiotics for spinal infections without complications.

关键词： Thoracic spine infection Pseudomonas fluorescens Spinal infection Case report

Magnetism of NaYbS2: From finite temperatures to ground state

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2024年第10期Mechanics & Astronomy) .卷 96-108页

作者： Weizhen Zhuo Zheng Zhang Mingtai Xie Anmin Zhang Jianting Ji feng jin Qingming Zhang School of Physical Science and Technology Lanzhou University Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of Sciences

Rare-earth chalcogenide compounds ARECh2（A=alkali or monovalent metal,RE=rare earth,Ch=O,S,Se,Te） are a large family of quantum spin liquid（QSL） candidate ***2is a representative member of the *** key issues on NaYbS2,particularly how to determine the highly anisotropic spin Hamiltonian and describe the magnetism at finite temperatures and the ground state,remain to be *** this paper,we conducted an in-depth and comprehensive study on the magnetism of NaYbS2from finite temperatures to the ground ***,we successfully detected three crystalline electric field（CEF） excitation energy levels using low-temperature Raman scattering *** them with the CEF theory and magnetization data,we worked out the CEF parameters,CEF energy levels,and CEF *** further determined a characteristic temperature of ～40 K,above which the magnetism is dominated by CEF excitations while below which the spinexchange interactions play a main *** characteristic temperature has been confirmed by the temperature-dependent electron spin resonance（ESR） ***-temperature ESR experiments on the dilute magnetic doped crystal of NaYb0.1Lu0.9S2further helped us to determine the accurate ***,we quantitatively obtained the spin-exchange interactions in the spin Hamiltonian by consistently simulating the magnetization and specific heat ***,the above studies allow us to explore the ground state magnetism of NaYbS2by using the density matrix renormalization *** combined numerical calculations and experimental results to demonstrate that the ground state of NaYbS2is a Dirac-like QSL.

关键词： anisotropic spin Hamiltonian quantum spin liquid rare-earth chalcogenide

Gut microbiota and healthy longevity

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China Life Sciences 2024年

作者： Jia Luo Shan Liang feng jin College of Psychology Sichuan Normal University Key Laboratory of Mental Health Institute of Psychology Chinese Academy of Sciences

Recent progress on the underlying biological mechanisms of healthy longevity has propelled the field from elucidating genetic modification of healthy longevity hallmarks to defining mechanisms of gut microbiota influencing it. Importantly, the role of gut microbiota in the healthy longevity of the host may provide unprecedented opportunities to decipher the plasticity of lifespan on a natural evolutionary scale and shed light on using microbiota-targeted strategies to promote healthy aging and combat age-related diseases. This review investigates how gut microbiota affects healthy longevity, focusing on the mechanisms through which gut microbiota modulates it. Specifically, we focused on the ability of gut microbiota to enhance the intestinal barrier integrity, provide protection from inflammaging, ameliorate nutrientsensing pathways, optimize mitochondrial function, and improve defense against age-related diseases, thus participating in enhancing longevity and healthspan.

关键词：