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Discrete numerical modeling of granular materials considering crushability

Journal of Mountain Science 2017年第4期14卷 758-770页

作者： QIAN jian-gu gu jian-bo gu Xiao-qiang HUANG Mao-song Key Laboratory of Geotechnieal and Underground Engineering of Ministry of Education Tongji UniversityShanghai 200092China Department of Geotechnical Engineering Tongji UniversityShanghai 200092China

The aim of this study is to numerically investigate the influence of particle breakage on the mechanical behavior of granular materials using a discrete element method(DEM). To enable particle crushing, non-crushable elementary particles are boned together to represents the granular aggregates which can be crushed when the external force exceeds its strength. The flaw of the aggregate was also modeled by randomly distributed void. Single particle crushing tests were carried out to determine the distribution of particle strength. The results of single particle crushing tests illustrate that the simulated single particle fracture strength and pattern agree well with the Weibull's distribution *** oedometer tests, drained monotonic and cyclic triaxial tests were also carried out to investigate the crushing of the aggregates and the associated mechanical behaviors. The effect of confining pressure on the crushing of aggregates and the mechanical behavior was also analyzed. It was found that the peak stress and dilation decrease significantly when particle crushing was *** deformation behavior of the specimen is essentially controlled by two factors: particle rearrangement-induced dilation and particle crushing-induced contraction. The increase of permanent strain and the reduction of dilation were observed during cyclic loading and they tend to reach a stable state after a certain number of cycles. The crushing of aggregate is most significant in the first two cycles. The results also indicated that for the same axial strain the volumetric strain and the bound breakage in the cyclic loading tests are significantly larger than that in the monotonic loading tests,especially at high cyclic stress ratio.

关键词：颗粒破碎数值模拟粒状材料离散元法循环荷载试验固结试验力学行为颗粒强度

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各年龄段人群血清神经元特异性烯醇化酶与外周动脉硬化的相关性分析

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川北医学院学报 2024年第2期39卷 198-203页

作者：张小琴辜建伟杨云凤李芸刘菊华川北医学院附属医院老年科四川南充637000 川北医学院附属医院健康管理中心四川南充637000

目的:研究各年龄段人群血清神经元特异性烯醇化酶(NSE)与外周动脉硬化的相关性。方法:以体检人群为研究对象,收集一般临床资料,采用免疫化学发光法测定血清NSE浓度,通过肱-踝脉搏波传导速度(baPWV)评估外周动脉硬化;根据年龄将研究人群... 详细信息

目的:研究各年龄段人群血清神经元特异性烯醇化酶(NSE)与外周动脉硬化的相关性。方法:以体检人群为研究对象,收集一般临床资料,采用免疫化学发光法测定血清NSE浓度,通过肱-踝脉搏波传导速度(baPWV)评估外周动脉硬化;根据年龄将研究人群分为3组:青年组(≤44岁)、中年组(45~59岁)和老年组(≥60岁),评估不同年龄组血清NSE水平与baPWV及外周动脉硬化的相关性。结果:共纳入7338名研究对象,青年组2847例,中年组3614例,老年组877例;各年龄组中,血清NSE浓度、收缩压、超敏C反应蛋白均为baPWV的独立影响因素(P<0.05),年龄越大,血清NSE浓度与baPWV相关性越高;各年龄组中,血清NSE浓度、心率、吸烟史、高血压、糖尿病、空腹血糖、收缩压、舒张压、甘油三酯、肌酐、白细胞均为外周动脉硬化(baPWV≥1400 cm/s)的危险因素(P<0.05);青年组及中年组中,高密度脂蛋白是外周动脉硬化的保护因素(P<0.05)。按NSE浓度四分位数进一步将各组研究人群分为4组,校正分析影响外周动脉硬化的因素。结果提示,与Q1组相比,除青年组外,中年组及老年组发生外周动脉硬化的OR值均随NSE浓度梯度递增而逐步递增(P<0.05)。结论:各年龄组人群中,baPWV数值随血清NSE浓度增加而增加,NSE是外周动脉硬化的独立危险因素,随着NSE浓度梯度递增,中年及老年人群发生外周动脉硬化的风险也逐步递增。

关键词：外周动脉硬化神经元特异性烯醇化酶肱-踝脉搏波传导速度

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大流量高压共轨供油泵参数敏感性分析

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现代车用动力 2024年第2期 15-23页

作者：魏子朝乔信起王先勇顾坚张涛庄凤芝上海交通大学机械与动力工程学院上海200240 中国第一汽车股份有限公司无锡油泵油嘴研究所江苏无锡214063 一汽解放汽车有限公司商用车开发院江苏无锡214063

某柴油机需要较大供油流量,为优化大流量高压共轨供油泵(简称大流量泵)参数,使供油量及容积效率达标,搭建了大流量泵液力系统仿真模型并进行试验验证,应用蒙特卡洛方法仿真计算大流量泵在不同系列参数下的性能,通过线性回归与随机森林... 详细信息

某柴油机需要较大供油流量,为优化大流量高压共轨供油泵(简称大流量泵)参数,使供油量及容积效率达标,搭建了大流量泵液力系统仿真模型并进行试验验证,应用蒙特卡洛方法仿真计算大流量泵在不同系列参数下的性能,通过线性回归与随机森林回归进行参数敏感性分析。结果表明:2种回归分析方法计算结果基本一致,大流量泵在标定工况下的供油量和容积效率的高敏感性参数均为柱塞直径、进油阀座锥角、进油压力、柱塞升程和进油计量阀内径。

关键词：高压共轨供油泵敏感性分析仿真蒙特卡洛法回归

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Entropy majorization, thermal adiabatic theorem, and quantum phase transitions

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Frontiers of physics 2012年第2期7卷 244-251页

作者： Shi-jian gu (1) 1. Department of Physics and Institute of Theoretical Physics The Chinese University of Hong Kong Hong Kong China

Let a general quantum many-body system at a low temperature adiabatically cross through the vicinity of the system＇s quantum critical point. We show that the system＇s temperature is signif- icantly suppressed due to both the entropy majorization theorem in quantum information science and the entropy conservation law in reversible adiabatic processes. We take the one-dimensional transverse-field Ising model and the spinless fermion system as concrete examples to show that the inverse temperature might become divergent around the systems＇ critical points. Since the temper- ature is a measurable quantity in experiments, it can be used, via reversible adiabatic processes at low temperatures, to detect quantum phase transitions in the perspectives of quantum information science and quantum statistical mechanics.

关键词： quantum phase transition entropy majorization

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Liquid-phase epitaxial layer by layer brushing fabrication of metalorganic frameworks films

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Nano Research 2024年第6期17卷 5698-5704页

作者： Li-Mei Chang Rui Zhai Zhi-Zhou Ma jian-Dong Huang Zhi-Gang gu jian Zhang College of Chemistry Fuzhou UniversityFuzhou 350108China State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002China University of Chinese Academy of Sciences Beijing 100049China

Development of metal-organic framework(MOF)films is of great importance to expand their ***,we report a facile and universal method of liquid-phase epitaxial(LPE)layer by layer(LBL)brushing approach for fabricating MOF films on various substrates in a high-throughput *** MOF films preparation method offers a great prospective to cost-effectively construct films with short preparation time and little reagent ***,this LBL brushing approach has been implemented successfully to assemble various MOF films,including HKUST-1,zeolitic imidazolate framework-8(ZIF-8),Cu(bdc),and Cu_(2)(L)_(2)P(L=bdc,ndc,and cam;P=dabco and bipy).Afterwards,the classic MOF HKUST-1 and ZIF-8 films were grown on sensor chip electrode and porous fiber support for good volatile organic compounds(VOCs)selective sensing and water purification *** study demonstrates that this LBL brushing preparation method can be employed to synthesize various MOF films with a variety of characteristics to realize their sensing and separation applications.

关键词： metal-organic framework porous materials layer by layer fabrication film

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Fidelity spectrum:A tool to probe the property of a quantum phase

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Chinese Physics B 2016年第3期25卷 84-90页

作者： Wing Chi Yu Shi-jian gu Department of Physics and ITR The Chinese University of Hong KongHong KongChina

Fidelity measures the similarity between two states and is widely adapted by the condensed matter community as a probe of quantum phase transitions in many-body systems. Despite its success in witnessing quantum critical points, information about the fine structure of a quantum phase one can get from this approach is still limited. Here, we proposed a scheme called fidelity spectrum, By studying the fidelity spectrum, one can obtain information about the characteristics of a phase. In particular, we investigated the spectra in the one-dimensional transverse-field Ising model and the two- dimensional Kitaev model on a honeycomb lattice. It was found that the sPectra have qualitative differences in the critical and non-critical regions of the two models. From the distributions of them, the dominating k modes in a particular phase could also be captured.

关键词： quantum phase.transitions quantum information quanfized spin models

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A Possible X-ray Quasi-periodic Oscillation in the Narrow-line Seyfert 1 Galaxy Mrk 142

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Research in Astronomy and Astrophysics 2024年第6期24卷 191-200页

作者： Xiao-gu Zhong jian-Cheng Wang Yong-Yun Chen Xiao-Ling Yu College of Physics and Electronic Engineering Qujing Normal UniversityQujing 655011China Yunnan Observatories Chinese Academy of SciencesKunming 650216China

A possible quasi-periodic oscillation(QPO) at frequency 7.045 × 10^(-5) Hz is found in the narrow-line Seyfert 1galaxy Mrk 142 in the data of XMM-Newton collected on 2020 April *** find that the QPO signal is statistically significantly larger than the 5σ level and highly coherent with quality factor Q > 5 at the 0.3–10 keV band by using the method of the Lomb–Scargle Periodogram,the Weighted Wavelet Z-transform and the *** analyze the data in 0.3–0.6 keV,0.6–1 keV,1–3 keV and 3–10 keV energy bands,and find obvious QPO signals at 0.3–0.6 keV and 1–3 keV *** then analyze the time-average spectra and time variability at the QPO frequency of 7.045 × 10^(-5) Hz,and use a model to fit *** find that the QPO signal mainly comes from the X-ray hot corona.

关键词： X-rays:galaxies galaxies:Seyfert accretion accretion disks radiation mechanisms:general

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Optimal placement of piezoelectric active bars in vibration control by topological optimization

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Acta Mechanica Sinica 2008年第6期24卷 699-708页

作者： guozhong Zhao jian Wang Yuanxian gu State Key Laboratory of Structural Analysis for Industrial Equipment Department of Engineering Mechanics Dalian University of Technology Dalian 116024 China

A continuous variable optimization method and a topological optimization method are proposed for the vibration control of piezoelectric truss structures by means of the optimal placements of active bars. In this optimization model, a zero-one discrete variable is defined in order to solve the optimal placement of piezoelectric active bars. At the same time, the feedback gains are also optimized as continuous design variables. A two-phase procedure is proposed to solve the optimization problem. The sequential linear programming algorithm is used to solve optimization problem and the sensitivity analysis is carried out for objective and constraint functions to make linear approximations. On the basis of the Newmark time integration of structural transient dynamic responses, a new sensitivity analysis method is developed in this paper for the vibration control problem of piezoelectric truss structures with respect to various kinds of design variables. Numerical examples are given in the paper to demonstrate the effectiveness of the methods.

关键词： Piezoelectric intelligent truss Vibrationcontrol Design optimization Sensitivity analysis

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经皮冠状动脉腔内冲击波球囊导管成形术在血管内超声指导下对左主干重度钙化治疗的有效性和安全性分析

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中国介入心脏病学杂志 2024年第7期32卷 383-389页

作者：刘丰齐鲍骏李拜红陈翀昊高长征过云峰顾鑫顾建斌王晓彦江南大学附属医院心内科江苏无锡214000 惠山区第二人民医院心内科江苏无锡214000

目的探讨经皮冠状动脉腔内冲击波球囊导管成形术或称血管内碎石术(IVL)在血管内超声(IVUS)指导下治疗左主干(LM)重度钙化病变的有效性和安全性。方法纳入2022年10月至2024年4月期间江南大学附属医院收治的26例LM(口部、体部、分叉)重度... 详细信息

目的探讨经皮冠状动脉腔内冲击波球囊导管成形术或称血管内碎石术(IVL)在血管内超声(IVUS)指导下治疗左主干(LM)重度钙化病变的有效性和安全性。方法纳入2022年10月至2024年4月期间江南大学附属医院收治的26例LM(口部、体部、分叉)重度钙化患者,年龄72.0(61.8,75.4)岁。在IVUS指导下应用IVL对钙化病变进行预处理,再行经皮冠状动脉介入治疗(PCI)置入支架/药物球囊。所有患者均在应用IVL前后、PCI术后使用IVUS进行评估,并比较治疗前后IVUS腔内相关数据[斑块负荷(PB)、最小管腔面积(MLA)、最小管腔直径(MLD)]以及钙化断裂数、最小支架面积(MSA)、支架膨胀系数(EXP)等。结果26例患者(2例开口病变、7例体部病变、17例主干末端分叉病变)中稳定型心绞痛(SAP)7例,不稳定型心绞痛(UA)10例,急性ST段抬高型心肌梗死(STEMI)4例和非ST段抬高型心肌梗死(NSTEMI)5例。钙化最严重部位处PB在IVL后减小[79.50(76.00,83.75)%比80.00(76.00,83.75)%,P=0.001],MLA在IVL后增大[3.39(3.14,3.68)mm2比3.38(3.14,3.67)mm2,P=0.039],MLD在IVL后增大[3.21(3.07,3.30)mm比3.20(3.07,3.30)mm,P=0.024],100%有钙化环断裂(2例1个,9例2个,15例≥3个),100%成功置入支架/药物球囊,EXP高达(89.15±4.42)%,MSA 7.20(6.46,7.45)mm2。术后随访3个月均无心绞痛、复发性心肌梗死和死亡等不良事件发生。结论LM重度钙化病变经IVUS评估经IVL预处理后成功完成PCI术,IVL可作为LM重度钙化治疗的选择。

关键词：血管内碎石术左主干冠状动脉钙化血管内超声

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固态脱硝技术处理垃圾焚烧烟气的工程应用

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工业安全与环保 2024年第6期50卷 69-71,103页

作者：张亚刘祥王磊姚辉宋帅杨花安吴炜辰顾坚江苏海默环保科技有限公司江苏南通226000 北控环境再生能源沭阳有限公司江苏宿迁223600

以设计处理能力300t/d的机械炉排炉为研究对象,系统研究了PNCR、SNCR和渗滤液联合处理的方式以及智能调控程序的引入对烟囱出口NOx和NH3浓度的影响。结果表明,PNCR+SNCR+渗滤液或PNCR+渗滤液的联用均能有效降低NOx的排放值,但其应对低... 详细信息

以设计处理能力300t/d的机械炉排炉为研究对象,系统研究了PNCR、SNCR和渗滤液联合处理的方式以及智能调控程序的引入对烟囱出口NOx和NH3浓度的影响。结果表明,PNCR+SNCR+渗滤液或PNCR+渗滤液的联用均能有效降低NOx的排放值,但其应对低负荷工况的氨逃逸控制能力不佳;PNCR+SNCR联用和单独使用PNCR,能够应对不同工况,将NOx和NH3的时均值分别稳定控制于90 mg/m^(3)和6mg/m^(3)以下,但PNCR单独使用时吨耗明显增加。通过引入智能调控系统,NOx和NH3的处理稳定性大幅提升,改善了整体的脱硝效率,降低了脱硝剂的使用成本。

关键词：固态脱硝脱硝剂智能调控 PNCR

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