检索结果-南通市图书馆

Surface effects of liquid metal amoeba

Science Bulletin 2017年第10期62卷 700-706页

作者： Liang Hu jing Li Jianbo Tang jing liu Beijing Key Laboratory of Cryo-Biomedical Engineering and Key Laboratory of Cryogenics Technical Institute of Physics and Chemistry Chinese Academy of Sciences Department of Biomedical Engineering School of Medicine Tsinghua University

Liquid metals(LM) such as eutectic gallium-indium and gallium-indium-tin are important functional liquid-state metal materials with many unique properties, which have attracted wide attentions especially from soft robot area. Recently the amoeba-like transformations of LM on the graphite surface are discovered, which present a promising future for the design and assemble of self-fueled actuators with dendritically deformable body. It appears that the surface tension of the LM can be significantly reduced when it contacts graphite surface in alkaline solution. Clearly, the specific surface should play a vital role in inducing these intriguing behaviors, which is valuable and inspiring in soft robot design. However, the information regarding varied materials functions underlying these behaviors remains unknown. To explore the generalized effects of surface materials in those intriguing behavior, several materials including glass, graphite, nickel and copper oxides(CuO) were comparatively investigated as substrate *** results were obtained that only LM amoeba transformations were observed on graphite and CuO surfaces. In order to identify the proper surface condition for LM transformation, the intrinsic properties of substrate surfaces, such as the surface charge and roughness, as well as the specific interaction with LM like wetting behavior and mutual locomotion etc., were characterized. The integrated results revealed that LM droplet appears more likely to deform on surfaces with higher positive surface charge density, higher roughness and less bubble generation on them. In addition, another surface material,CuOx, is identified to own similar ability to graphite, which is valuable in achieving amoeba-like transformation. Moreover, this study offers a fundamental understanding of the surface properties in realizing LM amoeba transformations, which would shed light on packing and structure design of liquid metal-based soft device within multi-material s

关键词： Surface effect Liquid metal amoeba Surface tension Substrate materials

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

Eliminating mother-to-child transmission of HBV:progress and challenges in China

引用

Frontiers of Medicine 2020年第1期14卷 21-29页

作者： Wenzhan jing Jue liu Min liu Department of Epidemiology and Biostatistics School of Public HealthPeking UniversityBeijing 100191China

China has the world’s largest burden of hepatitis B virus(HBV)infection,but the country has made considerable progress in preventing its mother-to-child transmission(MTCT)in the past three *** feat is made possible due to the high coverage of birth-dose hepatitis B vaccine(HepB,>95%),hepatitis B surface antigen(HBsAg)screening for pregnant women(>99%),and hepatitis B immunoglobulin plus HepB for newborns whose mothers are HBsAg positive(>99%).Studies on the optimal antiviral treatment regimen for pregnant women with high HBV-DNA load have also been ***,China still faces challenges in eliminating MTCTof *** overall HBsAg prevalence among pregnant women is considered an intermediate *** prevalence of HBsAg among pregnant women from remote,rural,or ethnic minority areas is higher than that of the national level because of limited health resources and public health education for *** coverage for maternal and child healthcare and immunization services should be improved,especially in western *** of current services to prevent MTCTof HBV with other relevant health services can increase the acceptability,efficiency,and coverage of these services,particularly in remote areas and ethnic minority *** doing so,progress toward key milestones and targets to eliminate hepatitis B as the main public health threat by 2030 can be achieved.

关键词： hepatitis B virus mother-to-child transmission progress challenge

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

Linking satellite-based spring phenology to temperate deciduous broadleaf forest photosynthesis activity

引用

International Journal of Digital Earth 2014年第11期7卷 881-896页

作者： jing-jing Zhao Liang-yun liu Key Laboratory of Digital Earth Science Center for Earth Observation and Digital EarthUniversity of Chinese Academy of SciencesBeijingChina

Satellite-based remote sensed phenology has been widely used to assess global climate ***,it is constrained by uncertain linkages with photo-synthesis *** dynamic threshold methods were employed to retrieve spring phenology metrics from four Moderate Resolution Imaging Spectro-radiometer(MODIS)products,including fraction of Absorbed Photosyntheti-cally Active Radiation(fAPAR),Leaf Area Index(LAI),Normalized Difference Vegetation Index(NDVI),and Enhanced Vegetation Index(EVI)for three temperate deciduous broadleaf forests in North America between 2001 and *** MODIS-based spring phenology metrics were subsequently linked to the photosynthetic curves(daily gross primary productivity,GPP)measured by an eddy covariance flux *** 20% dynamic threshold spring onset metrics from MODIS products were closer to the photosynthesis onset metrics at the date of 2% GPP increase for NDVI and fAPAR,and closer to the date of 5%and 10% increase of GPP for EVI and LAI,*** 50% dynamic threshold onset metrics were closer to the photosynthesis onset metrics at the date of 10%GPP increase for NDVI,and closer to the date of 20% GPP increase for fAPAR,LAI and EVI,*** results can improve our knowledge on the photosynthesis activity status of remotely sensed spring phenology metrics.

关键词： MODIS spring phenology deciduous broadleaf forest GPP eddy covariance flux tower photosynthesis activity period

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

Numerical investigation of frictional drag reduction with an air layer concept on the hull of a ship

引用

Journal of Hydrodynamics 2020年第3期32卷 591-604页

作者： Jun Zhang Shuo yang jing liu College of Aerospace Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China Energy Research Institute@NTU Nanyang Technological UniversitySingapore

A novel air bubble lubrication method using the winged air induction pipe (WAIP) device is used to reduce the frictional drag of the hull of the ship and hence increase the efficiency of the propulsion system. This bubble lubrication technique utilizes the negative pressure region above the upper surface of the hydrofoil as the ship moves forward to drive air to the skin of the hull. In the present study, the reduction rate of the drag by applying the WAIP device is numerically investigated with the open source toolbox OpenFOAM. The generated air layer and the bubbles are observed. The numerical results indicate that the reduction rate of the drag closely depends on the depth of the submergence of the hydrofoil, the angle of attack of the hydrofoil, and the pressure in the air inlet. It is also proportional to the air flow rate. The underlying physics of the fluid dynamics is explored.

关键词： Winged air induction pipe(WAIP) drag reduction frictional resistance reduction hull of ship OpenFOAM

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

Theoretical study of reduction mechanism of Fe_(2)O_(3) by H_(2) during chemical looping combustion

引用

Chinese Journal of Chemical Engineering 2021年第9期34卷 175-183页

作者： Feng liu jing liu yu Li Ruixue Fang State Key Laboratory of Coal Combustion School of Energy and Power EngineeringHuazhong University of Science and TechnologyWuhan 430074China

An atomic-level insight into the H_(2)adsorption and oxidation on the Fe_(2)O_(3)surface during chemicallooping combustion was provided on the basis of density functional theory calculations in this *** results indicated that H_(2)molecule most likely chemisorbs on the Fe_(2)O_(3)surface in a dissociative *** decomposed H atoms then could adsorb on the Fe and O atoms or on the two neighboring O atoms of the *** particular,the H_(2)molecule adsorbed on an O top site could directly form H_(2)O precursor on the O_(3)-terminated ***,the newly formed H-O bond was activated,and the H atom could migrate from one O site to another,consequently forming the H_(2)O *** the H_(2)oxidation process,the decomposition of H_(2)molecule was the rate-determining step for the O_(3)-terminated surface with an activation energy of 1.53 ***,the formation of H_(2)O was the ratedetermining step for the Fe-terminated surface with an activation energy of 1.64 *** Feterminated surface is less energetically favorable for H_(2)oxidation than that the O_(3)-terminated surface owing to the steric hindrance of Fe *** results provide a fundamental understanding about the reaction mechanism of Fe_(2)O_(3)with H_(2),which is helpful for the rational design of Fe-based oxygen carrier and the usage of green energy resource such as H_(2).

关键词： Chemical-looping combustion Fe_(2)O_(3)oxygen carrier H_(2)adsorption Density functional theory Reaction 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

Structural phase transition,strength,and texture in vanadium at high pressure under nonhydrostatic compression

引用

Chinese Physics B 2018年第3期27卷 335-341页

作者： Lun Xiong jing liu School of Intelligent Manufacturing Sichuan University of Arts and ScienceDazhou 635000China DaZhou Industrial Technology Institute of Intelligent Manufacturing Dazhou 635000China Beijing Synchrotron Radiation Facility Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China

The structural phase transition,strength,and texture of vanadium have been studied under nonhydrostatic compression up to 70 GPa using an angle-dispersive radial x-ray diffraction technique in a 2-fold paranomic diamond anvil cell and up to 38 GPa using an angle-dispersive x-ray diffraction technique in a modified Mao-Bell diamond anvil cell at room *** have confirmed a phase transition from body-centered cubic structure to rhombohedral structure at 27-32 GPa under nonhydrostatic *** radial x-ray diffraction data yields a bulk modulus K_(0)=141(5)GPa and its pressure derivative K_(0)'=5.4(7)for the bcc phase and K_(0)=154(13)GPa with K_(0)′=3.8(3)for the rhombohedral phase atψ=54.7°.The nonhydrostatic x-ray diffraction data of both bcc and rhombohedral phases yields a bulk modulus K_(0)=188(5)GPa with K_(0)′=2.1(3).Combined with the independent constraints on the high-pressure shear modulus,it is found that the vanadium sample can support a differential stress of-1.6 GPa when it starts to yield with plastic deformation at-36 GPa.A maximum differential stress as high as-1.7 GPa can be supported by vanadium at the pressure of-47 *** addition,we have investigated the texture up to 70 GPa using the software package *** is convinced that the body-centered cubic to rhombohedral phase transition and plastic deformation due to stress under high pressures are responsible for the development of texture.

关键词： phase transition strength texture vanadium

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

Deformation behaviors of four-layered U-shaped metallic bellows in hydroforming

引用

Chinese Journal of Aeronautics 2020年第12期33卷 3479-3494页

作者： jing liu Zhiyong LV yang liu Lanyun LI Key Laboratory of Materials Processing Engineering School of Material Science and EngineeringXi'an Shiyou UniversityXi'an 710065China Key Laboratory of Advanced Manufacture Technology for Automobile Parts(Chongqing University of Technology) Ministry of EducationChongqing 400054China Bime Bremen Institute of Mechanical EngineeringMAPEX Center for Materials and ProcessingUniversity of BremenBremen 28359Germany

Because of the complex constraint effects among layers in multi-layered metallic bellows hydroforming,the stress concentration and defects such as wrinkling and fracture may easily *** is a key to reveal the deformation behaviors in order to obtain a sound *** on the ABAQUS platform,a 3 D-FE model of the four-layered U-shaped metallic bellow hydroforming process is established and validated by *** stress and strain distributions,wall thickness variations and bellow profiles of each layer in the whole process,including bulging,folding and springback stages,are *** deformation behaviors of bellows under different forming conditions are *** is found that the wall thinning degrees of different layer vary after hydroforming,and is the largest for the inner layer and smallest for the outer *** folding stage,the wall thinning degree of the crown point increases lineally,and the difference among layers increases as the process *** displacements of the crown point decrease from the inner layer to the outer *** springback,the U-shaped cross section changes to a tongue shape,the change of convolution pitch is much larger than the change of convolution height,and the springback values of the inner layer are smaller than the outer *** increase in the internal pressure and die spacing cause the maximum wall thinning degree and springback *** changing of process parameters,bellows with deep convolution are easily encountered wall thinning during hydroforming and convolution distortion after *** research is helpful for precision forming of multi-layered bellows.

关键词： Deformation behaviors Four-layered U-shaped bellow Hydroforming Numerical simulation Springback

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

Global Epidemic of Ebola Virus Disease and the Importation Risk into China: An Assessment Based on the Risk Matrix Method

引用

Biomedical and Environmental Sciences 2023年第1期36卷 86-93页

作者： SHANG Wei jing jing Wen Zhan liu Jue liu Min School of Public Health Peking UniversityBeijing 100191China

Objective To analyze the global epidemic status of the Ebola virus disease(EVD) and assess the importation risk into *** Data from World Health Organization reports were used. We described the global epidemic status of EVD from 1976–2021, and assessed and ranked the importation risk of EVD from the diseaseoutbreaking countries into China using the risk matrix and Borda count methods, *** From 1976–2021, EVD mainly occurred in western and central Africa, with the highest cumulative number of cases(14,124 cases) in Sierra Leone, and the highest cumulative fatality rate(85%) in the Congo. Outbreaks of EVD have occurred in the Democratic Republic of the Congo and Guinea since 2018. The importation risk into China varies across countries with outbreaks of *** Democratic Republic of the Congo had an extremely high risk(23 Borda points), followed by Guinea and Liberia. Countries with a moderate importation risk were Nigeria, Uganda, Congo, Sierra Leone,Mali, and Gabon, while countries with a low importation risk included Sudan, Senegal, and Co te d’*** China is under the risk of EVD importation with the globalization and severe epidemic status of EVD. Key attention need to be paid to the Democratic Republic of the Congo, Guinea, and Liberia. Therefore, it is necessary to prevent and prepare in advance for importation risk in China.

关键词： Ebola virus disease Infectious disease Importation risk Risk matrix method

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

A VERTICAL 2-D NUMERICAL SIMULATION OF SUSPENDED SEDIMENT TRANSPORT

引用

Journal of Hydrodynamics 2007年第2期19卷 217-224页

作者： ZHANG jing-xin liu Hua Department Of Engineering Mechanics Shanghai Jiaotong University Shanghai 200240 China

Numerical simulation of sediment transport and bed evolution has become an important technique in the sediment research. In this article, a numerical model of suspended sediment transport was proposed, which was established in the vertical σ coordinate for fitting the free surface and bottom. In the research of the sediment transport, the predominant factors were found to be the eddy diffusion, the settling velocity, the bed condition and so on. By the aid of the model in the article, the contribution of the Rouse parameter to the vertical profile of sediment concentration was clarified, which was identical to the theoretical results. In the comparison of the numerical results with laboratory data, the agreement between experimental data and numerical results was reached except for some data. And the possible reasons for the disagreement were discussed.

关键词： suspended sediment transport 2-D numericalmodel σ coordinate

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

An Approach to Automatic Performance Prediction forCloud-Enhanced Mobile Applications with Sparse Data

引用

Journal of Computer Science & Technology 2017年第5期32卷 936-956页

作者： Wei-Qing liu jing Li School of Computer Science and Technology University of Science and Technology of China Hefei 230026 China

In mobile cloud computing (MCC), offloading compute-intensive parts of a mobile application onto the cloud is an attractive method to enhance application performance. To make good offloading decisions, history-based machinelearning techniques are proposed to predict application performance under various offloading schemes. However, the data sparsity problem is common in a realistic MCC scenario but is rarely the concern of existing work. In this paper, we employ a two-phase hybrid framework to predict performance for cloud-enhanced mobile applications, which is designed to be robust to the data sparsity. By training several multi-layer neural networks with historical execution records, the first phase automatically predicts some intermediate parameters for each execution of an application. The models learned by these neural networks can be shared among different applications, thus alleviating the data sparsity. Based on these predicted intermediate parameters and the application topology, the second phase deterministically calculates the estimated values of the performance metrics. The deterministic algorithm can partially guarantee the prediction accuracy of newly published applications even with no execution records. We evaluate our approach with a cloud-enhanced object recognition application and show that our approach can precisely predict the application performance and is robust to data sparsity.

关键词： mobile cloud computing (MCC) performance prediction neural network

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

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：