检索结果-南通市图书馆

The influence of nano-particle tracers on the slip length measurements by microPTV

Acta Mechanica Sinica 2013年第3期29卷 411-419页

作者： Xu Zheng Gao-Pan Kong Zhan-Hua silber-li State Key Laboratory of Nonlinear Mechanics Institute of MechanicsCAS

Direct measurement of slip length is based on the measured fluid velocity near solid boundary. However, previous micro particle image velocimetry/particle tracking velocimetry （microPIV/PTV） measurements have reported surprisingly large measured near-wall velocities of pressure-driven flow in apparent contradiction with the no-slip hy-pothesis and experimental results from other techniques. To better interpret the measured results of the microPIV/PTV, we performed velocity profile measurements near a hy-drophilic wall （z = 0.25-1.5 μm） with two sizes of tracer particles （φ 50 nm and φ200 nm）. The experimental results indicate that, at less than 1 μm from the wall, the deviations between the measured velocities and no-slip theoretical values obviously decrease from 93% of φ200 nm particles to 48% of φ50 nm particles. The Boltzmann-like exponential measured particle concentrations near wall were found. Based on the non linear Boltzmann distribution of particle concentration and the effective focus plane thickness, we illustrated the reason of the apparent velocity increase near wall and proposed a method to correct the measured velocity profile. By this method, the deviations between the corrected measured velocities and the no-slip theoretical velocity decrease from 45.8% to 10%, and the measured slip length on hy-drophilic glass is revised from 75 nm to 16 nm. These results indicated that the particle size and the biased particle concentration distribution can significantly affect near wall velocity measurement via microPIV/PTV, and result in larger measured velocity and slip length close to wall.

关键词： MicroPIV/PTV · Slip length · Nano-particle tracer · Particle concentration distribution · Boltzmann distribution

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

Flow characteristics of liquid with pressure-dependent viscosities in microtubes

引用

Acta Mechanica Sinica 2006年第1期22卷 17-21页

作者： Zhanhua silber-li Haihang Cui Yuping Tan Patrick Tabeling LNM Institute of Mechanics CAS Beijing 100080 China SIAMM Shanghai University Shanghai 200072 China MMN ESPCI 10 rue Vauquelin Paris 75231 France

It is obvious that the pressure gradient along the axial direction in a pipe flow keeps constant according to the Hagen-Poiseuille equation. However, recent experiments indicated that the distribution of the pressure seemed no longer linear for liquid flows in microtubes driven by high pressure （1-30MPa）. Based on H-P equation with slip boundary condition and Bridgman＇s relation of viscosity vs. static pressure, the nonlinear distribution of pressure along the axial direction is analyzed in this paper. The revised standard Poiseuille number with the effect of pressure-dependent viscosity taken into account agrees well with the experimental results. Therefore, the dependence of the viscosity on the pressure is one of the dominating factors under high driven pressure, and is represented by an important property coefficient α of the liquid.

关键词： Microfluidic liquid Microtube Viscosity

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 CAPILLARITY ON NANO-liTER FLOWRATE MEASUREMET WITH DISPLACEMET METHOD

引用

Journal of Hydrodynamics 2007年第5期19卷 594-600页

作者： GUO Qiang CHENG Rui silber-li Zhan-hua State Key Laboratory of Nonlinear Mechanics Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China Shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai 200072 China

Nanoqiter flowrate measurements in micro-tubes with displacement method were performed and the effect of capillarity force on the accuracy was investigated through lab experiments and theoretical analysis in this article. The experiments were conducted under the pressure drops ranging from 1 kPa to 10 kPa in a circular pipe with a diameter of 50 pm, to give the pressure-flowrate （P-Q） relation and verify the applicability of the classical Hagen-Poiseuille （HP） formula. The experimental results showed that there existed a discrepancy between the experimental data and the theoretical values predicted by the HP formula if the capillary effect was not considered, which exceeded obviously the limit of the system error. And hence a modified formula for the relation, taking the capillary effect into account, was presented through theoretical deduction, and after the HP formula had been modified the error was proved to be less than 3%, which was permitted in comparison with the system error. It was also concluded that only by eliminating the effect of the capillary force in experiments could the original HP formula be employed to predict the pressure-flowrate relation in the Hagen-Poiseuille flow in the micro-tube.

关键词： nano-liter flowrate measurement,Hagen-Poiseuille (HP) formula displacement method,capillarity force

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

Measures of Relative and Absolute Convergence and Pro-poor Growth with an Illustration based on China(2010–2018)

引用

China & World Economy 2024年第2期32卷 1-41页

作者： Elena Bárcena-Martin Jacques silber Yuan Zhang Facultad de Ciencias Económicas y Empresariales Universidad de MálagaSpain Department of Economics Bar-Ilan UniversityIsrael China Center for Economic Studies Fudan UniversityChina

Income mobility is a key issue for understanding the process of economic growth and distributional *** economists have used the concept of“pro-poor growth”to examine,with individual-level panel data,whether the poor benefit more than the rich from economic growth by tracking the extent of income mobility among different population *** is also literature in macroeconomics on the measurement of *** paper introduces population-weighted relative and absolute indices of mobility,convergence,and pro-poor growth;it also distinguishes between anonymous and nonanonymous approaches to these *** empirical analysis is based on Chinese panel data for the period 2010–*** both absolute and relative terms,income growth in China was greater for individuals with an initially lower income but only for lower income deciles in relative *** was also an overall increase in individual welfare from anonymous and nonanonymous perspectives,which was higher among younger *** welfare of the poor did not increase more than that of the *** results shed light on the evolution of income distribution in China during the past decade's rapid economic growth.

关键词： anonymous and nonanonymous approach convergence exchange and structural mobility pro-poor growth

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

Semi-automated detection of rangeland runoff and erosion control berms using high-resolution topography data

引用

International Soil and Water Conservation Research 2024年第1期12卷 217-226页

作者： li li Changjiang River Scientific Research Institute of Changjiang Water Resources Commission Wuhan430010China Research Center on Mountain Torrent&Geologic Disaster Prevention Ministry of Water ResourcesWuhan430010China University of Arizona School of Natural Resources and the EnvironmentTucsonAZ85719USA

An inventory of topographic modifications is essential to addressing their impacts on hydrological and morphological processes in human-altered ***,such inventories are generally *** study presents two workflows for semi-automatic detection of linear earthen runoff and erosion control berms in rangelands using high-resolution topographic *** workflows consist of initial object identification by applying either morphological grayscale reconstruction(MGR)or the Geomorphon(GEO)method,followed by identification refinements through filters based on objects’horizontal and vertical *** sites were selected within the Altar Valley,Arizona,in the southwestern United *** site was used for developing workflows and optimizing filter thresholds,and the other two sites were used to validate *** results showed that:1)The MGR-based workflow methodology could produce final precision and detection rates of up to 92%and 75%,respectively,and take less than 5 s for a 10.1 km^(2) site;2)The workflow based on the MGR method yielded greater identification accuracy than did the GEO workflow;3)Object length,orientation,and eccentricity were important characteristics for identifying earthen berms,and are sensitive to general channel flow direction and berm shape;4)Manual interrogation of topographic data and imagery can significantly improve identification precision *** proposed workflows will be useful for developing inventories of runoff and erosion control structures in support of sustainable rangeland management.

关键词： Earthen berm Rangeland Grayscale morphological reconstruction Geomorphon liDAR

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

Effects of mid-passage gap with a variable surface angle on a turbine vane endwall’s aerothermal and film cooling performances

引用

Chinese Journal of Aeronautics 2024年第6期37卷 20-37页

作者： Zhiyu li Kaiyuan ZHANG Zhigang li Jun li Institute of Turbomachinery Xi’an Jiaotong UniversityXi’an 710049China

The mid-passage gap is an inevitable structure in a vane passage due to turbine vanes being manufactured *** coolant from this gap is able to prevent hot mainstream ingression and provide cooling protection for the endwall.A novel idea of enlarging the endwall’s coverage area and reducing the endwall’s thermal load by applying the mid-passage gap with variable surface angles is carried out in this *** endwall’s aerothermal and film cooling performances under four mid-passage gap modes at three typical mass flow ratio conditions are numerically *** indicate that under the traditional mid-passage mode,the coolant flows into the mainstream with a perpendicular incidence angle and can’t stick to the ***,cooling failure occurs,and the endwall’s thermal load is badly *** film cooling level at the suction-side endwall is improved when applying the mid-passage gap of a 45surface angle due to the secondary vortex being *** addition,when applying the mid-passage gap of a 135surface angle,the horseshoe vortex is pushed away,and the coverage area at the pressure-side endwall is enlarged *** best film cooling performance is achieved when the upstream surface angle is 135and the downstream surface angle is 45due to the adiabatic film cooling effectiveness being increased at both the pressure-and suction-side *** the mass flow ratio is 1.5%,the coverage area is enlarged by 43%,and the area-averaged adiabatic film cooling effectiveness is increased by 37%,when compared with those under the traditional mid-passage mode.

关键词： Film cooling Heat transfer Surface angle Mid-passagegap Turbinevane endwall

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

Perturbed low-thrust geostationary orbit transfer guidance via polynomial costate estimation

引用

Chinese Journal of Aeronautics 2024年第3期37卷 181-193页

作者： Zhao li Hengnian li Fanghua JIANG Junfeng li State Key Laboratory of Astronautic Dynamics Xi’an Satellite Control CenterXi’an 710043China School of Aerospace Engineering Tsinghua UniversityBeijing 100084China

This paper proposes an optimal,robust,and efficient guidance scheme for the perturbed minimum-time low-thrust transfer toward the geostationary *** Earth’s oblateness perturbation and shadow are taken into *** is difficult for a Lyapunov-based or trajectory-tracking guidance method to possess multiple characteristics at the same time,including high guidance optimality,robustness,and onboard computational *** this work,a concise relationship between the minimum-time transfer problem with orbital averaging and its optimal solution is identified,which reveals that the five averaged initial costates that dominate the optimal thrust direction can be approximately determined by only four initial modified equinoctial orbit elements after a coordinate *** on this relationship,the optimal averaged trajectories constituting the training dataset are randomly generated around a nominal averaged *** polynomial regression models are trained on the training dataset and are regarded as the costate *** the transfer,the spacecraft can obtain the real-time approximate optimal thrust direction by combining the costate estimations provided by the estimators with the current state at any ***,all these computations onboard are *** simulation results show that the proposed guidance scheme possesses extremely high guidance optimality,robustness,and onboard computational efficiency.

关键词： Low thrust Orbital transfer Trajectory optimization Guidance Indirect method Orbital averaging Machine learning Geostationary satellites

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

Theoretical Analysis of Cooperative Driving at Idealized Unsignalized Intersections

引用

Tsinghua Science and Technology 2024年第1期29卷 257-270页

作者： Shen li Jiawei Zhang Zhenwu Chen li li Department of Civil Engineering Tsinghua UniversityBeijing 100084China Department of Automation Tsinghua UniversityBeijing 100084China Shenzhen Urban Transport Planning Center Co. Ltd.Shenzhen 518000China

Cooperative driving is widely viewed as a promising method to better utilize limited road resources and alleviate traffic *** recent years,several cooperative driving approaches for idealized traffic scenarios(i.e.,uniform vehicle arrivals,lengths,and speeds)have been ***,theoretical analyses and comparisons of these approaches are *** this study,we propose a unified group-by-group zipper-style movement model to describe different approaches synthetically and evaluate their *** derive the maximum throughput for cooperative driving plans of idealized unsignalized intersections and discuss how to minimize the delay of *** obtained conclusions shed light on future cooperative driving studies.

关键词： cooperative driving connected and automated vehicles unsignalized intersection

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

Ultrathin organic solvent nanofiltration membrane with polydopamine-HKUST-1 interlayer for organic solvent separation

引用

Journal of Environmental Sciences 2024年第7期141卷 182-193页

作者： Haike li Xindong li Guozai Ouyang lijinhong Huang Lang li Wenhao li Wanfu Huang Duokun li Ganzhou Key Laboratory of Basin Pollution Simulation and Control Jiangxi University of Science and TechnologyGanzhou 341000China Innovation Center for Water Quality Security Technology at Ganjiang River Basin Jiangxi University of Science and TechnologyGanzhou 341000China School of Architecture and Design Jiangxi University of Science and TechnologyGanzhou 341000China WA School of Mines:Minerals Energy and Chemical EngineeringCurtin UniversityWA 6845Australia School of Materials Science and Engineering Tiangong UniversityTianjin 300387China

Polydopamine(PDA)and metal-organic skeleton HKUST-1 were co-deposited on the base membrane of hexamethylenediamine(HDA)-crosslinked polyetherimide(PEI)ultrafiltration membrane as the interlayer,and high-throughput organic solvent nanofiltration membrane(OSN)was prepared by interfacial polymerization and solvent activation *** polyamide(PA)layer surface roughness from 28.4 nm in PA/PEI to 78.3 nm in PA/PDA-HKUST-10.6/PEI membrane,reduced the thickness of the separation layer from 79 to 14 nm,and significantly improved the hydrophilic,thermal and mechanical *** flux of the PA/PDA-HKUST-10.6/PEI membrane in a 0.1 g/L Congo Red(CR)ethanol solution at 0.6 MPa test pressure reached 21.8 L/(m^(2)·hr)and the rejection of CR was 92.8%.Solvent adsorption test,N,N-dimethylformamide(DMF)immersion experiment,and long-term operation test in ethanol showed that the membranes had high solvent *** solvent flux test demonstrated that,under the test pressure of 0.6 MPa,the flux of different solvents ranked as follows:methanol(56.9 L/(m^(2)·hr))>DMF(39.6 L/(m^(2)·hr))>ethanol(31.2 L/(m^(2)·hr))>IPA(4.5 L/(m^(2)·hr))>N-hexane(1.9 L/(m^(2)·hr)).The ability of the membranes to retain dyes in IPA/water dyes solution was also *** flux of the membrane was 30.4 L/(m^(2)·hr)and the rejection of CR was 91.6%when the IPA concentration reached 50%.This OSN membrane-making strategy is economical,environment-friendly and efficient,and has a great application prospect in organic solvent separation systems.

关键词： Interfacial polymerization Organic solvent nanofiltration Interlayer Metal-organic frameworks Polydopamine

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

Heralded entanglement between error-protected logical qubits for fault-tolerant distributed quantum computing

引用

Science China(Physics,Mechanics & Astronomy) 2024年第2期67卷 25-33页

作者： Jialun li Zhihao Xie Yachen li Yansen liang Zhenhua li Tao li MIIT Key Laboratory of Semiconductor Microstructure and Quantum Sensing School of PhysicsNanjing University of Science and TechnologyNanjing 210094China National Laboratory of Solid State Microstructures Nanjing UniversityNanjing 210093China

Quantum error correction is essential for achieving reliable quantum information processing tasks,as it can mitigate the detrimental effects of noise by encoding single-qubit information into a larger quantum ***,the generation of distributed entanglement between logical qubits located within two spatially separated nodes presents a significant resource-intensive challenge that has yet to be *** we present a heralded protocol for generating distributed entanglement between two nonlocal error-protected logical qubits.A high-dimensional single photon can evolve physical qubits into a logical qubit that entangles with the photon and then converts logical qubit-photon entanglement into entanglement between two logical qubits,when the photon state is properly tuned and an effective photon-spin interface between single photons and individual spins is ***,the success of the entanglement generation is heralded by the detection of the photon,and the corresponding efficiency can,in principle,approach *** distinguished features make our protocol highly appealing for future large-scale quantum technologies.

关键词： quantum networks distributed entanglement error-protected logical qubits high-dimensional photons

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：