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Experimental study on performance of spring damping support structure system for large deformation tunnel in soft rock

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Underground Space 2024年第2期15卷 221-243页

作者： jinfeng xu Xiongyao Xie Zhou Shi Wuqiang Cai Dinglun xu Chen xu Department of Geotechnical Engineering College of Civil EngineeringTongji UniversityShanghai 200092China Key Laboratory of Geotechnical and Underground Engineering Ministry of EducationTongji UniversityShanghai 200092China Zhaotong City Zhaolu Expressway Investment and Development Co. ZhaotongYunnan Province 657000China Institute of Rock Mechanics Ningbo UniversityNingboZhejiang 315211China

According to the convergence confinement theory,it is an effective measure to control the large deformation of high ground stress in fractured soft rock tunnels by using yielding *** yielding support can be classified as either radial or circumferential yielding *** yielding support is achieved by transforming radial displacement into circumferential tangential closure without compromising the support capacity of the primary lining support *** on this,and inspired by the design principle of dampers,a yielding support structure system with spring damping elements as its core was developed,based on the connection characteristics of steel arches in highway tunnel,which can provide increasing support resistance in the yielding deformation *** the mechanical properties of spring damping elements were obtained through indoor axial pressure and flexural *** addition,according to these results with numerical calculations,the yielding support structure system with embedded spring damping elements can reduce the internal force of the support structure by approximately 10%and increase the area of the plastic zone of the surrounding rock by 11.23%,which can fully utilize the self-bearing capacity of surrounding rock and verify the effectiveness of circumferential yielding ***,the spring damping support structure system was designed with reference to the construction process of the tunnel excavated by drilling and blasting method,and the transformation of the spring damping element to spring damping support structure was *** on field test results,surrounding ground pressure for the yielding support optimization scheme was reduced by 40%and more evenly distributed,resulting in the successful application and a reduction in the construction cost of large deformation tunnels in soft rock.

关键词： Soft rock Highway tunnel Convergence confinement method Circumferential yielding support with spring damping element Numerical calculations Field test

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Nonalcoholic Fatty Liver Disease:Changes in Gut Microbiota and Blood Lipids

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Journal of Clinical and Translational Hepatology 2024年第4期12卷 333-345页

作者： Keen Yang Jieying Zeng Huaiyu Wu Huiyu Liu Zhimin Ding Weiyu Liang Linghu Wu Ziwei Lin Wenhui Huang jinfeng xu Fajin Dong Department of Ultrasound Shenzhen People’s Hospital(The Second Clinical Medical CollegeJinan UniversityThe First Affiliated HospitalSouthern University of Science and Technology)ShenzhenGuangdongChina

Background and Aims:The global prevalence of nonalcoholic fatty liver disease(NAFLD)is 25%.This study aimed to explore differences in the gut microbial community and blood lipids between normal livers and those affected by NAFLD using 16S ribosomal deoxyribonucleic acid ***:Gut microbiome profiles of 40 NAFLD and 20 non-NAFLD controls were *** about four blood lipids and 13 other clinical features was *** were divided into three groups by ultrasound and FibroScan,those with a normal liver,mild FL(FL1),and moderate-to-severe FL(FL2).FL1 and FL2 patients were divided into two groups,those with either hyperlipidemia or non-hyperlipidemia based on their blood *** keystone species within the groups were identified using univariate analysis and a specificity–occupancy *** difference in biochemical parameters ion NAFLD patients and healthy individuals were identified by detrended correspondence analysis and canonical correspondence ***:Decreased gut bacterial diversity was found in patients with ***/Bacteroidetes decreased as NAFLD *** and Ruminococcus 2 were the most representative fatty-related *** pyruvic transaminase,aspartate aminotransferase,and white blood cell count were selected as the most significant biochemical *** of areas under the curve identified two microbiomes combined with the three biochemical indexes that identified normal liver and FL2 very well but performed poorly in diagnosing ***:Faecalibacterium and Ruminococcus 2,combined with glutamate pyruvic transaminase,aspartate aminotransferase,and white blood cell count distinguished *** speculate that regulating the health of gut microbiota may release NAFLD,in addition to providing new targets for clinicians to treat NAFLD.

关键词： Liver Gut microbiota Blood lipids Nonalcoholic fatty liver disease Hyperlipidemia

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软岩隧道支护让压体系优化及安全状态易损性评价

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同济大学学报（自然科学版） 2024年第7期52卷 1040-1048页

作者：周彪李锟铻谢雄耀徐金峰刘龙坤同济大学岩土及地下工程教育部重点实验室上海200092 同济大学土木工程学院上海200092

软岩隧道围岩参数变异性大,支护体系与围岩相互作用不确定性强,易发生大变形等安全问题,为此国内外开展了隧道让压支护优化等工作以应对上述风险,但对其安全状态评价仍面临诸多难题。设计了一种新型柔-刚型让压接头,并基于可靠度分析方... 详细信息

软岩隧道围岩参数变异性大,支护体系与围岩相互作用不确定性强,易发生大变形等安全问题,为此国内外开展了隧道让压支护优化等工作以应对上述风险,但对其安全状态评价仍面临诸多难题。设计了一种新型柔-刚型让压接头,并基于可靠度分析方法,从易损性出发,综合拱顶沉降及初衬强度破坏准则,提出了基于概率的隧道开挖安全状态易损性评价方法。其通过利用概率有限元分析围岩‒支护相互作用,拟合形成极限状态功能函数响应面,经由随机抽样获得隧道开挖失效概率与可靠度指标;以此为基础,建立拱顶沉降与结构应力响应之间的拟合关系,提出了基于拱顶沉降的结构极限状态条件概率计算方法,并根据概率分布区间划定易损区进行支护安全性评价。基于上述理论方法,结合工程实际,开展了新型让压支护与传统刚性支护的易损性对比分析,验证了让压支护体系在大变形承载可靠性方面的优势。

关键词：软岩支护让压概率易损评价

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高职铁道工程技术专业群模块化课程体系建设研究与实践

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西安轨道交通职业教育研究 2024年第2期 11-15页

作者：徐金锋西安铁路职业技术学院陕西西安710600

基于职业能力对专业进行模块化课程体系建设,是当今高职院校普遍采用的方法。通过企业调研,归纳岗位群的主要岗位,对核心岗位进行职业能力分析,按照底层共享、中层分立、顶层拓展的原则构建四大模块。本文以西安铁路职业技术学院铁工专... 详细信息

基于职业能力对专业进行模块化课程体系建设,是当今高职院校普遍采用的方法。通过企业调研,归纳岗位群的主要岗位,对核心岗位进行职业能力分析,按照底层共享、中层分立、顶层拓展的原则构建四大模块。本文以西安铁路职业技术学院铁工专业群建设背景下高速铁路精测精调课程改革为例,阐述如何基于职业工作过程重构课程内容,系统化的进行设计课程模块、课程实施、教学评价,从而落实教育部对三教改革的要求,为专业群模块课程改革提供参考借鉴。

关键词：模块化课程铁工类工单

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高速铁路精测精调人才职业特质培养探索与实践

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西安轨道交通职业教育研究 2024年第1期 56-59页

作者：徐金锋西安铁路职业技术学院陕西西安710600

高速铁路是国家经济社会发展的主动脉,是交通强国战略的重要支撑。轨道平顺性对高铁安全运行至关重要,精密测量和精准调整是保障轨道平顺的关键技术。随着高铁轨道平顺精度标准越来越高(亚毫米级),加之维修天窗时间短,就需要高铁施工、... 详细信息

高速铁路是国家经济社会发展的主动脉,是交通强国战略的重要支撑。轨道平顺性对高铁安全运行至关重要,精密测量和精准调整是保障轨道平顺的关键技术。随着高铁轨道平顺精度标准越来越高(亚毫米级),加之维修天窗时间短,就需要高铁施工、运营维护作业人员具备更高水平的精测精调能力。因此,怎样才能培养出适应高铁精测精调工作要求、具备更高水平职业技能素养的人才,成为轨道交通类高职院校面临的重要课题。

关键词：精测精调职业特质三教改革 “课堂革命”

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钙离子光时标守时技术研究

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仪器仪表学报 2024年第2期45卷 145-151页

作者：史丰丰程梦飞王德豪徐金锋李国俊北京卫星导航中心北京100094 中国科学院精密测量科学与技术创新研究院武汉430071

近年来光学频率标准(光钟)技术快速发展,国际时间频率咨询委员会计划于2030年用光钟重新定义“秒”,并提出了技术路线,光时标的研究也成为时间频率领域的研究热点。利用钙离子光钟驾驭微波氢钟,开展高精度光时标信号TS(Ca^(+))产生技术... 详细信息

近年来光学频率标准(光钟)技术快速发展,国际时间频率咨询委员会计划于2030年用光钟重新定义“秒”,并提出了技术路线,光时标的研究也成为时间频率领域的研究热点。利用钙离子光钟驾驭微波氢钟,开展高精度光时标信号TS(Ca^(+))产生技术研究。结果表明,钙离子光钟准连续稳定运行率可达87%,稳定度达8×10^(-17)/day。对光钟和氢钟的频率比对测量分别采用微波频率锁定方案(上转换)和光生超稳微波方案(下转换),上转换方案引入了并放大了噪声,测量数据比氢钟稳定度差,而下转换方案产生超稳微波,测量数据频率稳定度与氢钟几乎重合,实现了光钟对氢钟的准确测量。将测量得到的频差数据直接置入相位微跃计,产生光时标TS(Ca^(+)),独立运行的光时标TS(Ca^(+))在一个月内与UTC偏差保持在0.6 ns以内。研究成果为报送秒定义数据和驾驭自由原子时TAI提供技术基础,为提升我国光时标守时能力提供了宝贵的技术支持和工程经验。

关键词：钙离子光钟光时标上转换测量下转换测量光钟驾驭微波钟

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不完全契约视角下医院内部激励机制的构建

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医学与哲学 2024年第8期45卷 26-29页

作者：许金凤林鹏朱大伟郭娜兰陵县中医医院财务科山东临沂277712 临沂市检验检测中心办公室山东临沂276000 北京大学药学院药事管理与临床药学系北京100191 北京大学医药管理国际研究中心北京100191 中国人口与发展研究中心战略研究部北京100081

如何构建内部激励机制,使医院能够提供安全、有效、方便、价廉的医疗卫生服务,是公立医院高质量发展的重点内容。在不完全契约理论框架下,以委托代理理论为基础,分析医院与医生之间契约的不完备性及其委托代理关系,探讨契约设计的关键问... 详细信息

如何构建内部激励机制,使医院能够提供安全、有效、方便、价廉的医疗卫生服务,是公立医院高质量发展的重点内容。在不完全契约理论框架下,以委托代理理论为基础,分析医院与医生之间契约的不完备性及其委托代理关系,探讨契约设计的关键问题,利用激励相容等相关原理,研究如何构建合理的医院内部激励机制和通过设计契约来促使医生的诊疗行为符合社会期望。本研究从价值导向、准租行为动机、激励有效性、共享风险、长期约束和审查机制等方面提出构建医院内部机制的政策建议,为公立医院薪酬制度改革提供参考依据。

关键词：公立医院激励机制不完全契约委托代理

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On the k-sample Behrens-Fisher problem for high-dimensional data

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Science China Mathematics 2009年第6期52卷 1285-1304页

作者： ZHANG JinTing xu jinfeng Department of Statistics and Applied Probability National University of Singapore3 Science Drive 2117546 Singapore

For several decades, much attention has been paid to the two-sample Behrens-Fisher (BF) problem which tests the equality of the means or mean vectors of two normal populations with unequal variance/covariance structures. Little work, however, has been done for the k-sample BF problem for high dimensional data which tests the equality of the mean vectors of several high-dimensional normal populations with unequal covariance structures. In this paper we study this challenging problem via extending the famous Scheffe’s transformation method, which reduces the k-sample BF problem to a one-sample problem. The induced one-sample problem can be easily tested by the classical Hotelling’s T 2 test when the size of the resulting sample is very large relative to its dimensionality. For high dimensional data, however, the dimensionality of the resulting sample is often very large, and even much larger than its sample size, which makes the classical Hotelling’s T 2 test not powerful or not even well defined. To overcome this difficulty, we propose and study an L 2-norm based test. The asymptotic powers of the proposed L 2-norm based test and Hotelling’s T 2 test are derived and theoretically compared. Methods for implementing the L 2-norm based test are described. Simulation studies are conducted to compare the L 2-norm based test and Hotelling’s T 2 test when the latter can be well defined, and to compare the proposed implementation methods for the L 2-norm based test otherwise. The methodologies are motivated and illustrated by a real data example.

关键词： χ 2-approximation χ 2-type mixtures high-dimensional data analysis Hotelling’s T 2 test k-sample test L 2-norm based test Primary 62H15 Secondary 62E17, 62E20

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Model Averaging Multistep Prediction in an Infinite Order Autoregressive Process

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Journal of Systems Science & Complexity 2022年第5期35卷 1875-1901页

作者： YUAN Huifang LIN Peng JIANG Tao xu jinfeng School of Statistics and Mathematics Zhejiang Gongshang UniversityHangzhou 310018China School of Mathematics and Statistics Zaozhuang UniversityZaozhuang 277000China School of Mathematics and Statistics Shandong University of TechnologyZibo 255000China Hangzhou College of Commerce Zhejiang Gongshang UniversityTonglu 311599China Department of Statistics and Actuarial Science The University of Hong KongHongKong 999077China

The key issue in the frequentist model averaging is the choice of *** this paper,the authors advocate an asymptotic framework of mean-squared prediction error(MSPE)and develop a model averaging criterion for multistep prediction in an infinite order autoregressive(AR(∞))*** the assumption that the order of the candidate model is bounded,this criterion is proved to be asymptotically optimal,in the sense of achieving the lowest out of sample MSPE for the samerealization *** and real data analysis further demonstrate the effectiveness and the efficiency of the theoretical results.

关键词： Asymptotic optimality autoregressive process multistep prediction the same-realization prediction

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Heat and mass transfer characteristics during rapid solidification of Fe-Cu peritectic alloys

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Science China(Physics,Mechanics & Astronomy) 2008年第5期51卷 459-469页

作者： xu jinfeng DAI FuPing WEI BingBo Department of Applied Physics Northwestern Polytechnical UniversityXi’an 710072China School of Materials Science and Engineering Xi’an University of TechnologyXi’an 710048China

The viscose flow and microstructure formation of Fe-Cu peritectic alloy melts are investigated by analyzing the velocity and temperature fields during rapid solidifi-cation,which is verified by rapid quenching *** is found that a large temperature gradient exists along the vertical direction of melt puddle,whereas there is no obvious temperature variation in the tangent direction of roller *** being sprayed from a nozzle,the alloy melt changes the magnitude and di-rection of its flow and velocity rapidly at a height of about 180 μ*** horizontal flow velocity increases rapidly,but the vertical flow velocity decreases sharply.A thermal boundary layer with 160-300 μm in height and a momentum boundary layer with 160-240 μm in thickness are formed at the bottom of melt puddle,and the Reynolds number Re is in the range of 870 to 1070 in the boundary *** the increase of Re number,the cooling rate increases linearly and the thickness of thermal boundary layer increases *** thickness of momentum boundary layer decreases slowly at first,then rises slightly and decreases *** Re 1024,the heat transfer becomes dominating and the liquid phase flow is suppressed,which results in the formation of fine and uniform equiaxed microstructures.

关键词： peritectic alloy liquid phase separation fluid flow heat transfer rapid solidification

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