检索结果-南通市图书馆

维普期刊数据库博看期刊

Influence of pier height on the safety of trains running on high-speed railway bridges during earthquakes

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 2102-2115页

作者： NIE Yu-tao GUO Wei jiang li-zhong YU Zhi-wu ZENG Chen WANG Yang HE Xu-en REN Shao-xun HUANG Ren-qiang liANG Guang-yue li Chang-qing School of Civil Engineering Central South UniversityChangsha 410075China National Engineering Research Center of High-speed Railway Construction Technology Central South UniversityChangsha 410075China

Sudden earthquakes pose a threat to the running safety of trains on high-speed railway bridges,and the stiffness of piers is one of the factors affecting the dynamic response of train-track-bridge *** this paper,a experiment of a train running on a high-speed railway bridge is performed based on a dynamic experiment system,and the corresponding numerical model is *** reliability of the numerical model is verified by ***,the experiment and numerical data are analyzed to reveal the pier height effects on the running safety of trains on *** results show that when the pier height changes,the frequency of the bridge below the 30 m pier height changes greater;the increase of pier height causes the transverse fundamental frequency of the bridge close to that of the train,and the shaking angle and lateral displacement of the train are the largest for bridge with 50 m pier,which increases the risk of derailment;with the pier height increases from 8 m to 50 m,the derailment coefficient obtained by numerical simulations increases by 75% on average,and the spectral intensity obtained by experiments increases by 120% on average,two indicators exhibit logarithmic variation.

关键词： pier height high-speed railway bridge running safety numerical model

高速铁路桥上设计震致轨道几何不平顺等效方法

在线全文

学校读者我要写书评

暂无评论

交通运输工程学报 2024年第3期24卷 110-123页

作者：余建周旺保蒋丽忠冯玉林刘祥中南大学土木工程学院湖南长沙410075 中南大学高速铁路建造技术国家工程研究中心湖南长沙410075 华东交通大学土木建筑学院江西南昌330013 福建理工大学土木工程学院福建福州350118

为解决考虑结构随机的设计震致轨道几何不平顺等效问题,建立了高速铁路轨道-桥梁系统的数值仿真模型,基于短时傅里叶变换和假设检验原理构造了设计震致轨道几何不平顺,建立了设计震致轨道几何不平顺的等效拟合模型和等效幅值反应谱,提... 详细信息

为解决考虑结构随机的设计震致轨道几何不平顺等效问题,建立了高速铁路轨道-桥梁系统的数值仿真模型,基于短时傅里叶变换和假设检验原理构造了设计震致轨道几何不平顺,建立了设计震致轨道几何不平顺的等效拟合模型和等效幅值反应谱,提出了考虑结构随机的等效幅值反应谱修正方法,结合震后实测轨道几何不平顺对设计震致轨道几何不平顺等效方法的合理性展开了评价。分析结果表明:在不同墩高条件下,采用正弦函数和一次函数的组合作为等效拟合模型可将设计震致轨道几何不平顺的拟合误差控制在10%以内;在设防地震和罕遇地震作用下,当修正系数分别取为3.0和1.5时,等效拟合模型与修正系数相乘得到的修正拟合模型可以满足随机结构的适用性需求;地震前后实测轨道几何不平顺形状和幅值均无明显差异,对应的横向车体加速度幅值误差小于5%,当地震强度较小时列车可正常运行,无需大幅度减速;与震后实测轨道几何不平顺相比,设计震致轨道几何不平顺使横向车体加速度幅值提升了近50%,基于设计震致轨道几何不平顺计算得到的震后行车速度阈值具有合理安全余量;建立的高速铁路桥上设计震致轨道几何不平顺等效方法可为高速铁路震后行车速度阈值确定与基于震后行车性能的抗震设计提供快速准确的手算方法。

关键词：桥梁工程高速铁路震后速度阈值轨道不平顺结构随机地震损伤行车安全

基于贝叶斯自优化Bi-LSTM组合网络的高速铁路轨道-桥梁系统震后响应预测方法

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3期31卷 965-975页

作者：彭康蒋丽忠周旺保余建向平吴凌旭 National Engineering Research Center of High-speed Railway Construction Technology Central South UniversityChangsha 410075China

中国高速铁路(HSR)规划建设逐渐向地震易发地区延伸,亟需一种及时、准确的灾后地震响应快速预测方法,以实现高速铁路系统运输生命线安全的快速评估。本文提出了一种基于贝叶斯自优化双向长短期记忆(Bi-LSTM)网络的快速预测方法,以经过... 详细信息

中国高速铁路(HSR)规划建设逐渐向地震易发地区延伸,亟需一种及时、准确的灾后地震响应快速预测方法,以实现高速铁路系统运输生命线安全的快速评估。本文提出了一种基于贝叶斯自优化双向长短期记忆(Bi-LSTM)网络的快速预测方法,以经过实验验证的高速铁路轨道-桥梁系统有限元模型地震动响应计算数据为样本,将预测地震响应和有限元计算结果进行比较,验证所提方法的精度和鲁棒性,表明该方法在预测高速铁路桥梁结构的非线性地震反应方面是有效的,且高速铁路轨道-桥梁系统的不同预测位置对预测精度的影响不明显;此外,为了降低神经网络训练数据量需求,提出了一种基于离散小波分解的分层聚类算法,结果表明,基于小波分解的分层聚类方法在保证预测精度的同时,有效地减少了训练地震集的输入数量。

关键词：高速铁路轨道-桥梁系统贝叶斯优化 Bi-LSTM神经网络离散小波分解聚类分析

非对称弦测法中基于梯度下降的轨道不平顺复原方法

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1期31卷 288-301页

作者：曾晨国巍刘汉云余志武蒋丽忠国振谈遂 School of Civil Engineering Central South UniversityChangsha 410075China National Engineering Research Center of High-speed Railway Construction Technology Changsha 410075China School of Civil Engineering Changsha University of Science&TechnologyChangsha 410114China School of Civil Engineering and Architecture Zhejiang UniversityHangzhou 310058China

本研究提出了一种基于梯度下降的轨道不平顺复原方法。基于非对称弦测法理论,轨道不平顺的复原过程可描述为一个欠定线性系统的优化问题。本文提出采用梯度下降法求解该优化问题,采用了考虑正则项的二次型代价函数。为了评估所提出方法... 详细信息

本研究提出了一种基于梯度下降的轨道不平顺复原方法。基于非对称弦测法理论,轨道不平顺的复原过程可描述为一个欠定线性系统的优化问题。本文提出采用梯度下降法求解该优化问题,采用了考虑正则项的二次型代价函数。为了评估所提出方法的性能,本研究搭建了一个轨道检测小车,并在一个缩尺桥梁模型上进行了现场试验。通过与水准仪测量值的比较,验证了基于梯度下降轨道不平顺复原方法具有良好精度。与传统的需要专门设计逆滤波器的轨道不平顺复原方法相比,本研究所提出的方法物理意义明确,只需基于非对称弦测法原理建立优化模型,这表明本方法在现场实测中具有良好的可操作性。此外,重复性评估表明,在调整不同的弦长以及多次重复测量时,本研究所提出的方法可复现一致的轨道不平顺结果,表明该方法具有良好的测量重复性。本研究所提出的方法可对轨道不平顺进行准确复原,为轨道平顺性状态及时有效评估提供数据支撑,进而保证列车运行的平稳与安全。

关键词：非对称弦测法轨道不平顺复原优化模型梯度下降方法逆滤波器法

Changes of ghrelin following oral glucose tolerance test in obese children with insulin resistance

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2008年第12期14卷 1919-1924页

作者： Xiu-Min Wang You-Jun jiang li liang li-zhong Du Department of endocrinology The Children's Hospital of ZhejiangUniversity School of Medicine 57 Zhugan Xiang Hangzhou310003 Zhejiang Province China

AIM： To characterize changes in ghrelin levels in response to oral glucose tolerance test （OGTT） and to correlate changes in ghrelin levels with changes in insulin and glucose following OGTT in Chinese obese children of Tanner Ⅰ and Ⅱ stage with insulin resistance. METHODS： 22 obese children with insulin resistance state were divided into four groups according to their Tanner stage and gender： boys of Tanner Ⅰ （fir- Ⅰ ）, boys of Tanner Ⅱ（BT-Ⅱ ）, girls of Tanner Ⅰ （GT- Ⅰ ）, girls of Tanner Ⅱ （GT-Ⅱ）. Ghrelin, insulin and glucose were measured at 0, 30, 60 and 120 rain following OGTT. The control children with normal BMI were divided into control boys of Tanner Ⅰ （CBT- Ⅰ, n = 6）, control boys of Tanner Ⅱ （CBT-Ⅱ, n = 5）, control girls of Tanner Ⅰ （CGT- Ⅰ, n = 6）, control girls of Tanner Ⅱ （CGT-Ⅱ, n = 5）. Fasting serum ghrelin levels were analyzed. RESULTS： Ghrelin levels were lower in obese groups. Ghrelin levels of control group decreased in Tanner Ⅱ stage （CGT- Ⅰ vs CGT-Ⅱ t = -4.703, P = 0.001; CBT- Ⅰ vs CBT- Ⅱ t = -4.794, P = 0.001）. Basal ghrelin levels in fir-Ⅱ decreased more significantly than that in BT- Ⅰ group （t = 2.547, P = 0.029）. Ghrelin levels expressed a downward trend after OGTT among obese children. The decrease in ghrelin levels at 60 min with respect to basal values was 56.9% in BT- Ⅰ. Ghrelin concentrations at 0 min correlated directly with glucose level at 0 min in fir- Ⅰ （r = 0.898, P = 0.015）. There wasn＇t a significant correlation of ghrelin changes with glucose changes and insulin changes during OGTT in obese children with insulin resistance. CONCLUSION： In conclusion, in obese children with insulin resistance, ghrelin levels decreased with advancing pubertal stage. Ghrelin secretion suppression following OGTT was influenced by gender and pubertal stage. Baseline ghrelin levels and ghrelin suppression after OGTT did not significantly correlate with the degree of insulin resistance and insulin sensitivity.

关键词： Ghrelin Oral glucose tolerance test Insulinresistance Obese children

不同品种糙米酚类物质抗氧化及体外降血糖活性评价

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

粮食与饲料工业 2024年第1期 40-45,52页

作者：杜昭换姜忠丽赵秀红沈阳师范大学粮食学院辽宁沈阳110034

以辽宁地区具有代表性的4个品种糙米(小粒香、Type-619、软米和龙粳)为研究对象,比较体外抗氧化与降血糖活性的差异,为今后糙米制品在原料选择、产品加工等方面提供科学依据。通过测定糙米提取物中多酚和黄酮含量,DPPH·、超氧阴离子自... 详细信息

以辽宁地区具有代表性的4个品种糙米(小粒香、Type-619、软米和龙粳)为研究对象,比较体外抗氧化与降血糖活性的差异,为今后糙米制品在原料选择、产品加工等方面提供科学依据。通过测定糙米提取物中多酚和黄酮含量,DPPH·、超氧阴离子自由基、ABTS+·清除率,以及葡萄糖苷酶和淀粉酶活性抑制率来评价糙米提取物的抗氧化和降血糖活性。结果表明,4个品种的糙米均具有较好的体外抗氧化能力和降血糖活性,其中抗氧化活性从大到小依次为软米>小粒香>Type-619>龙粳;4种糙米样品多酚提取物对两种酶活性均具有抑制作用,其中软米对酶活性的抑制率明显高于其他3个品种的抑制率,小粒香次之。

关键词：糙米多酚抗氧化能力葡萄糖苷酶淀粉酶降血糖活性

维普期刊数据库博看期刊

Preparation of the radioactive source core of iodine-125 seed

在线全文

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2009年第4期20卷 231-234页

作者： HE Jiaheng jiang lin li Xingliang zhong Wenbin WANG Jing MA Zongping JIAN Yuan Institute of Nuclear Physics and Chemistry China Academy of Engineering Physics Mianyang 621900 China

Iodine-125 seed is widely used in brachytherapy of intraocular tumors,brain tumors,and prostate ***1 25I seed is prepared by depositing 125I on a silver *** work was aimed at investigating effects of different parameters on the iodine adsorption,so as to optimize the process for preparing1 25I core of the *** parameters investigated include kind and concentration of halogenation reagent,halogenation time,adsorption time,pH and carrier iodine quantity.

关键词：放射性碘-125 能级核技术

Acute-on-chronic liver failure induced by antiviral therapy for chronic hepatitis C: A case report

在线全文

学校读者我要写书评

暂无评论

World Journal of Clinical Cases 2023年第30期11卷 7463-7468页

作者： jiang-li zhong ling-Wei Zhao Ying-Hua Chen Ya-Wen Luo Department of Infectious Diseases The Affiliated Hospital of Zunyi Medical UniversityZunyi 563000Guizhou ProvinceChina Department of Hematology The Affiliated Hospital of Zunyi Medical UniversityZunyi 563000Guizhou ProvinceChina

BACKGROUND There have been no reports of acute-on-chronic liver failure(ACLF)during treatment of chronic hepatitis C(CHC)with direct-acting antivirals(DAAs).CASE SUMMARY We report a 50-year-old male patient with *** patient sought medical attention from the Department of Infectious Diseases at our hospital due to severe yellowing of the skin and sclera,which developed 3 mo previously and attended two consecutive hospitals without finding the cause of liver *** was not until 1 mo ago that he was diagnosed with CHC at our *** discharge,he was treated with *** treatment,ACLF occurred,and timely measures such as liver protection,enzyme lowering,anti-infective treatment,and suppression of inflammatory storms were implemented to control the *** DAA drugs significantly improve the cure rate of ***,when patients have factors such as autoimmune attack,coinfection,or unclear hepatitis C virus genotype,close monitoring is required during DAA treatment.

关键词： Chronic hepatitis C Acute-on-chronic liver failure Direct acting antivirals Sofosbuvir-velpatasvir Case report

Experimental study on seismic behaviors of steel-concrete composite frames

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Central South University 2015年第11期22卷 4396-4413页

作者：戚菁菁蒋丽忠 School of Civil Engineering Hunan University of Science and Technology Department of Civil Engineering and Architecture Central South University

Steel-concrete composite frames are seeing increased use in earthquake region because of their excellent structural characteristics, including high strength, stiffness, and good ductility. However, there exist gaps in the knowledge of seismic behavior and the design provisions for these structures. In order to better understand the seismic behaviors of composite frame systems, eight steel-concrete composite frames were designed. These composite frames were composed of steel-concrete composite beams and concrete filled steel tube columns. The axial compression ratio of column, slenderness ratio and linear stiffness ratio of beam to column were selected as main design parameters. The low reversed cyclic loading tests of composite frame system were carried out. Based on test results, the seismic behaviors of composite frames such as failure mode, hysteresis curve, strength degradation, rigidity degradation, ductility and energy dissipation were studied. Known from the test phenomenon, the main cause of damage is the out-of-plane deformation of steel beam and the yielding destruction of column heel. The hysteretic loops of composite frame appear a spindle shape and no obvious pinch phenomenon. The results demonstrate that this type of composite frame has favorable seismic behaviors. Furthermore, the effects of design parameters on seismic behaviors were also discussed. The results of the experiment show that the different design parameter has different influence rule on seismic behaviors of composite frame.

关键词： composite frame steel-concrete composite beam conc