检索结果-南通市图书馆

Ferrite features in simulated transition zone of EH36 shipbuilding steel submerged arc welded by CaF_(2)-SiO_(2)-MnO fluxes

引用

Journal of Iron and Steel Research(International) 2024年第4期31卷 790-796页

作者： Ming Zhong Dong Hu Da-ming Guo Somnath Basu Cong Wang Key Laboratory for Ecological Metallurgy of Multimetallic Mineral(Ministry of Education) Northeastern UniversityShenyang 110819LiaoningChina School of Metallurgy Northeastern UniversityShenyang 110819LiaoningChina The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan 430081HubeiChina Department of Metallurgical Engineering and Materials Science Indian Institute of Technology BombayMumbai 400076MaharashtraIndia

Ferrite features in the simulated transition zone welded with CaF_(2)-SiO_(2)-MnO fluxes containing various MnO contents have been investigated.Confocal laser scanning microscopy has been applied to simulate the thermal cycling of the transition zone and the phase transformations during cooling have been in-situ observed.It has been found that the appearance temperature for ferrite side plate decreases with increasing Mn content in the weld metals caused by MnO content increasing.Meanwhile,growth rates for both ferrite side plate and acicular ferrite are significantly enhanced with a higher Mn content of weld metal.Furthermore,from the statistical fractions of salient microstructures,for all samples,the acicular ferrite,grain boundary ferrite,and polygonal ferrite take over more than 90%.It has also been demonstrated that with the increase in Mn content,the ferrite side plate fraction increases slightly from 5%to 10%and the acicular ferrite fraction shows a tendency of first increasing and then decreasing,which experiences the maximum with the flux containing 30 wt.%MnO.This phenomenon is believed to be controlled by the O and Mn contents in weld metals synergistically.

关键词： Submerged arc welding transition zone Phase transformation Microstructure

来源：

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

Influence of train speed and its mitigation measures in the short-and long-term performance of a ballastless transition zone

引用

铁道工程科学:英文版 2023年第4期31卷 309-324页

作者： Ana Ramos Rui Calçada António Gomes Correia Department of Civil Engineering Faculty of EngineeringUniversity of PortoCONSTRUCT-LESEPortoPortugal Department of Civil Engineering University of MinhoISISEGuimarãesPortugal

The ballastless track is nowadays the most popular railway system due to the required low number of maintenance opera-tions and costs,despite the high investment.The gradual change from ballasted to ballastless tracks has been occurring in Asia,but also in Europe,increasing the number of transition zones.The transition zones are a special area of the railway networks where there is an accelerated process of track degradation,which is a major concern of the railway infrastructure managers.Thus,the accurate prediction of the short-and long-term performance of ballastless tracks in transition zones is an important topic in the current paradigm of building/rehabilitating high-speed lines.This work purposes the development of an advanced 3D model to study the global performance of a ballastless track in an embankment-tunnel transition zone considering the influence of the train speed(220,360,500,and 600 km/h).Moreover,a mitigation measure is also adopted to reduce the stress and displacements levels of the track in the transition.A resilient mat placed in the tunnel and embank-ment aims to soften the transition.The behaviour of the track with the resilient mat is evaluated considering the influence of the train speed,with special attention regarding the critical speed.The used methodology is a novel and hybrid approach that allows including short-term and long-term performance,through the development of a powerful 3D model combined with the implementation of a calibrated empirical permanent deformation model.

关键词： Ballastless track Train speed Numerical modelling transition zone Critical speed

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Influence of Evaporating Under the Clouds on the Precipitation Stable Isotope in the transition zone Between Tibetan Plateau and Arid Region of China

引用

Chinese Geographical Science 2023年第4期33卷 764-778页

作者： GUI Juan LI Zongxing DU Fa ZHANG Baijuan XUE Jian CUI Qiao Observation and Research Station of Eco-Hydrology and National Park by Stable Isotope Tracing in Alpine Region Gansu Qilian Mountains Ecology Research CenterChinese Academy of SciencesLanzhou 730000China National Key Laboratory of Ecological Security and Sustainable Development in Arid Region Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China University of Chinese Academy of Sciences Beijing 100049China

Consideration of stable isotopes in precipitation is valuable for investigating hydrological processes.Therefore,correcting the measured isotopic composition of precipitation under below-cloud evaporation is necessary.An accurate description of the underlying processes affecting stable isotopic composition of precipitation could help improve our understanding of the water cycle.The transitivity between monsoonal and arid climates was reflected by the evaporation rate of falling raindrops in precipitation in the Qilian Mountains,a typical transition zone between Tibetan Plateau and arid region of China.Considering 1310 precipitation event-scale samples,based on stable isotope analysis method,the mean below-cloud evaporation rate(f)in the study area was measured as 12.00%during the summer half-year(May-October).The evaporation rate on the northern slopes(12.70%)of the Qilian Mountains in China was significantly higher than that on the southern slopes(9.98%).The transition between monsoonal and arid climates was reflected in the evaporation rate of falling raindrops during precipitation in the Qilian Mountains of China.Below-cloud evaporation contributed to a noticeable enrichment of stable isotopes in the precipitation in the study area.The monthly precipitationδ^(18)O enrichment rate in the Qilian Mountains of China from May to October was 29.18%,23.35%,25.60%,22.99%,31.64%,and 14.72%,respectively.For every 1.00%increase in the evaporation rate of raindrops in Qilian Mountains of China,the changes in the concentration of oxygen isotopes from the bottom of the clouds to the ground increased by 0.92‰;however,with an evaporation rate of<5.00%,for every 1.00%increase in the evaporation rate of raindrops the changes in the concentration of oxygen isotopes from the bottom of the clouds to the ground increased by 1.00‰could also be observed.Furthermore,altitude was an important factor affecting below-cloud evaporation in the study area.

关键词： below-cloud evaporation stable isotopes transition zone Qilian Mountains of China

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

OBSERVATION ON MICROSTRUCTURE OF LASER MELTED transition zone

引用

Acta Metallurgica Sinica(English Letters) 1990年第4期3卷 293-296页

作者： CHENG Yongxing LI Genfu YU Shaoluo Shanghai University of Engineering Science,Shanghai,China Dept.No.5,Shanghai University of Engineering Science,Shanghai 200051,China

The surface alloying specimen was made from the steel 45 substrate overcoating by oxygen-acetylene flame spraying Fe-Cr-Ni alloy powder and laser remelting.The chemical heterogeneity was clearly observed on the transition zone between the laser melted zone and heat-affected zone by means of EPMA,AES and SEM.This heterogeneity is rather serious during high temperature tempering,so the decarburization on the transition zone side and the recarburization on the melted zone side were found.

关键词： laser alloying heterogenity transition zone microstructure

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Damage Mechanism of Silicon Carbidemullite Bricks for transition zone of Cement Rotary Kilns

引用

China's Refractories 2020年第4期29卷 35-39页

作者： LI Guangqi CHEN Junhong JIA Yuanping LI Bin ZHU Bo CHEN Xiaoliang School of Materials Science and Engineering University of Science and Technology BeijingBeijing 100083China Zibo City Luzhong Refractory Co. Ltd.Zibo 255138China

In order to improve the service performance and explore the damage mechanism of silicon carbide-mullite bricks for the transition zone of cement rotary kilns,the phase composition and the microstructure of a used brick in the transition zone of a cement rotary kiln were analyzed by XRD,SEM and EDS.The results show that the liquid and alkali vapor phases generated by the reaction between cement materials and the silicon carbide-mullite brick mostly enter the silicon carbide-mullite brick through the pores;meanwhile,Ca+and K+in the cement penetrate through the liquid maintaining a high chemical potential energy to dissolve Al2O3 and SiO2 at the top of the liquid phase thus enhancing the phase penetration;with the decreasing temperature,crystals such as gehlenite,potassium feldspar and potassium chloride are precipitated,which destroy the original structure and increase the difference of thermal expansion coefficient between the high temperature dense end and the metamorphic layer thus resulting in cracks,spalling,and rupture.

关键词： cement rotary kiln transition zone silicon carbide-mullite brick damage mechanism

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Mechanical behavior of salt rocks: A geomechanical model

引用

Petroleum 2023年第4期9卷 508-525页

作者： Saeed Shad Negar Razaghi Davood Zivar Soheil Mellat Department of Chemical and Petroleum Engineering Sharif University of TechnologyTehranIran PanTerra Geoconsultants BV LeiderdorpNetherlands

The geomechanical behavior of salt rocks is a significant concern during drilling and development operations in some hydrocarbon reservoirs and underground gas storage sites.In this study,the static and dynamic salt rock geomechanical properties from a field in southwest Iran were evaluated using experiments such as waves'velocities,and thermo-mechanical coupled uniaxial and triaxial compression tests.As a result and by considering both the petrophysical well logs and laboratory data of the waves’velocities,it is observed that the elastic properties of the core samples are concentrated within a narrow range unless an abnormality causes scatter.The results of uniaxial compression tests showed that rock strength decreases with increasing temperature linearly.In addition,the reduction of rock strength was observed with increasing porosity of the core samples as expected.In the case of triaxial compression tests,applying confining pressure on the core sample caused an increment in rock strength,while temperature decreased rock strength.The temperature also increased cohesion and decreases friction angle.The ratio of changes in stress to strain was used to investigate the dynamic changes in the geomechanical state.The maximum 0.25 damage factor was observed for the core samples for different definitions of the damage factor.Finally,we propose a novel analytical model to predict the stress-strain behavior of salt rocks at different conditions.The model was validated using experimental results and indicated a satisfactory accuracy.

关键词： Salt rock Underground gas storage Geomechanics Dynamic and static mechanical properties transition zone Damage factor

来源：

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

Optical Properties of Cirrus transition zones over China Detected by CALIOP

引用

Journal of Meteorological Research 2017年第3期31卷 576-585页

作者： Hongke CAI Yunfei FU Quanliang CHEN Xiao FENG Xin TIE Ranting TAO Kepiao XU School of Atmospheric Science Chengdu University of Information Technology/Plateau Atmospheric and Environment Laboratory of Sichuan Province School of Earth and Space Sciences University of Science and Technology of China

A transition zone near cirrus lateral boundaries can be detected by CALIOP （cloud-aerosol lidar with orthogonal polarization）. In the present study, for such transition zones over China, a number of optical properties, such as the backscatter coefficient and depolarization ratio, showed transitional characteristics between cirrus and clear sky. The stepped horizontal profile showed sharp changes in particle number and morphology between cirrus clouds and clear sky. The color ratio, however, was unable to show cirrus transition features because of the low signal-to-noise ratio. Typical ice particles presented a color ratio of 0.55-1.25 and a depolarization ratio of greater than 0.12, which were significantly higher than those of clear sky. Therefore, optical properties in transition took the form of stepwise hori- zontal profiles. The proportion of typical-featured particles also demonstrated a stepped horizontal profile similar to the optical characteristics, but the relationship between the proportion and the optical characteristics was not uniform in the cirrus clouds, transition zone, and clear sky. Therefore, the optical changes in the transition zone were caused by not only the change in particle concentration, but also the change in the particles themselves. The probability dens- ity distribution of the transition-zone widths showed a positive skewness distribution, and transition zones with widths of 3-5 km occurred most frequently. Overall, transition-zone width decreased with increasing temperature and increased with increasing vertical and horizontal wind speeds. This trend demonstrated independence with the direc- tion of the vertical and horizontal winds. These observations implied that the transitional features were caused by ma- terial exchange, such as entrainment and turbulent transport, near the cirrus lateral boundaries, and by the phase trans- formation of particles, such as sublimation.

关键词： cirrus transition zone lidar temperature wind speed

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

The role of water in Earth's mantle

引用

National Science Review 2020年第1期7卷 224-232页

作者： Eiji Ohtani Graduate School of Science Tohoku University

Geophysical observations suggest that the transition zone is wet locally. Continental and oceanic sediment components together with the basaltic and peridotitic components might be transported and accumulated in the transition zone. Low-velocity anomalies at the upper mantle–transition zone boundary might be caused by the existence of dense hydrous magmas. Water can be carried farther into the lower mantle by the slabs. The anomalous Q and shear wave regions locating at the uppermost part of the lower mantle could be caused by the existence of fluid or wet magmas in this region because of the water-solubility contrast between the minerals in the transition zone and those in the lower mantle. δ-H solid solution AlO2H–MgSiO4H2carries water into the lower mantle. Hydrogen-bond symmetrization exists in high-pressure hydrous phases and thus they are stable at the high pressures of the lower mantle. Thus, theδ-H solid solution in subducting slabs carries water farther into the bottom of the lower mantle. Pyrite FeO2Hxis formed due to a reaction between the core and hydrated slabs. This phase could be a candidate for the anomalous regions at the core–mantle boundary.

关键词： water hydrous phase subducting slab transition zone lower mantle hydrogen-bond symmetrization core–mantle boundary

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Zonal differences in prostate diseases

引用

Chinese Medical Journal 2012年第9期125卷 1523-1528页

作者： JIANG Qi XIA Shu-jie Department of Urology Shanghai First People's HospitalShanghai Jiao Tong UniversityShanghai 200080China

Regardless of its relatively small size, the prostate is the most common site of pathology in human male, and the prostate is the site of the two most frequent medical problems affecting elderly men, benign prostatic hyperplasia （BPH） and prostate cancer （PCa）. Using the urethra as the key anatomical reference point, the prostate is conventionally divided into three distinct zones： peripheral zone, transition zone, and central zone. This morphology is of clinical significance in the development of age-associated conditions such as BPH and PCa.

关键词： prostate cancer benign prostatic hyperplasia peripheral zone transition zone

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Spatial structure and seasonal changes of nekton assemblages in the Taiwan Strait

引用

Acta Oceanologica Sinica 2016年第6期35卷 59-67页

作者： SONG Puqing LIN Longshan LI Yuan ZHONG Zhihui The Third Institute of Oceanography State Oceanic Administration

The Taiwan Strait is a transition zone between the East China Sea and the South China Sea with unique hydrology and a geographical environment that creates special marine community features.To analyze the spatial structure and seasonal changes of the nekton assemblages in the Taiwan Strait,seasonal experimental trawl surveys were conducted during 2006-2007.The results showed that there were two assemblages in the area with different sets of species,and the average similarity within each group varies between 39.38% and 74.20%.By using multivariate statistical analysis and analyzing the distribution of dominant species,we found that the structures of the assemblages had obvious seasonal variation.The middle region from the Putian transect to the Xiamen transect could be considered a mixing area for the two assemblages.The analysis of the relationship between species assemblages and environmental factors indicated that temperature was the most important factor affecting the community structure in cold seasons,and 22.5°C and 17°C could be considered dividing lines for spring and winter,respectively.In warm seasons,the most important factor was water depth,but the relationship with depth was not as significant,with a correlation between 0.264 and 0.399.The seasonal changes of nekton assemblages basically reflected the dynamic currents in the Taiwan Strait.The south coastal assemblage extended to nearly the entire area of the Taiwan Strait along with a strong and intense warm current that shrinks in spring and winter when the southward intrusion of the cold Zhejiang-Fujian coastal current becomes stronger.The impact of shortterm and long-term environmental changes,such as extreme weather,global warming and human activity on nekton assemblages,had been recognized but need further research.Our study on nekton assemblages could be used as a baseline for measuring future changes.

关键词： nekton assemblages species composition spatial structure transition zone Taiwan Strait

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：