检索结果-南通市图书馆

Water film coated composite liquid metal marble and its fluidic impact dynamics phenomenon

在线全文

学校读者我要写书评

暂无评论

Frontiers in Energy 2016年第1期10卷 29-36页

作者： Yujie DING Jing LIU Key lab of Cryogenics and Beijing Key lab of CryoBiomedicalEngineering Technical Institute of Physics and Chemistry ChineseAcademy of Sciences Beijing 100190 China Key lab of Cryogenics and Beijing Key lab of CryoBiomedicalEngineering Technical Institute of Physics and Chemistry ChineseAcademy of Sciences Beijing 100190 Department of Biomedical Engineering School of Medicine Tsinghua University Beijing 100084China

A composite liquid metal marble made of metal droplet coated with water film was proposed and its impact dynamics phenomenon was disclosed. After encapsulating the liquid metal into water droplets, the fabricated liquid marble successfully avoided being oxygenized by the metal fluid and thus significantly improved its many physical capabilities such as surface tension modification and shape control. The striking behaviors of the composite liquid metal marbles on a substrate at room temperature were experimentally inves- tigated in a high speed imaging way. It was disclosed that such marbles could disintegrate, merge, and even rebound when impacting the substrate, unlike the existing dynamic fluidic behaviors of liquid marble or metal droplet. The mechanisms lying behind these features were preliminarily interpreted. This fundamental finding raised profound multiphase fluid mechanics for understanding the complex liquid composite which was also critical for a variety of practical applications such as liquid metal jet cooling, inkjet printed electronics, 3D printing or metal particle fabrication etc.

关键词： liquid metal marble metallic droplet composite fluid impact dynamics multiphase fluid mechanics

NUMERICAL SIMULATION OF UNSTEADY TURBULENT FLOW INDUCED BY TWO-DIMENSIONAL ELEVATOR CAR AND COUNTER WEIGHT SYSTEM

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2007年第6期19卷 720-725页

作者： SHI Li-qun LIU Ying-zheng JIN Si-yu CAO Zhao-min Power Machinery Engineering lab Key Lab of Education Ministry of China School of Mechanical Engineering Shanghai Jiaotong University Shanghai 200240 China

A two-dimensional model of unsteady turbulent flow induced by high-speed elevator system was established in the present study. The research was focused on the instantaneous variation of the aerodynamic force on the car structure during traversing motion of the counter weight in the hoistway. A dynamic meshing method was employed to treat the multi-body motion system to avoid poor distortion of meshes. A comprehensive understanding of this significant aspect was obtained by varying the horizontal gap （δ =0.1m, 0.2m, and 0.3m） between the elevator car and the counter weight, and the moving speed （ U 0= 2m/s, 6m/s, and 10m/s） of the elevator system. A pulsed intensification of the aerodynamic force on the elevator car and subsequent appearance of large valley with negative aerodynamic force were clearly observed in the numerical results. In parameters studied （ δ =0.1m, U 0= 2m/s, 6m/s, 10m/s）, the peaked horizontal and vertical forces are respectively 7-11 and 4.3-5.65 times of that when the counter weight is far from the car. These results demonstrated the prominent influence of the traversing counter weight on aerodynamic force on the elevator car, which is of great significance to designers of high-speed elevator system.

关键词： high-speed elevator turbulent flow aerodynamic force Computational Fluid Dynamics (CFD)

Preparation and Luminescence Properties of the New Long Phosphorescent Phosphors Ba_(1-x)Ca_xAl_2O_4∶Eu ^(2+), Dy^(3+)

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2004年第1期22卷 129-132页

作者：李少霞何大伟成正维刘春棠刘端阳康凯邓朝勇 Key lab of Materials for Information Storage and Display

New long phosphorescent phosphors Ba 1-xCa xAl 2O 4∶Eu 2+, Dy 3+ with tunable color emission were prepared and studied. The emission spectra show that the tuning range of the color emission of the phosphors is between 498 and 440 nm, which is dependent on x, under the excitation of UV. The wavelength of the afterglow increases with the increasing of x until x equals 0.6. The XRD patterns show that the single phase limit in the phosphors is below x value of 0 4. The Thermoluminescence spectra were measured to investigate the traps created by the doping of Dy 3+.

关键词： opstics afterglow luminescence Ba 1-xCa xAl 2O 4∶Eu 2+, Dy 3+ rare earths

The spatial distribution of archaeal lipids in a mesoscale subtropical watershed, Southeast China

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2016年第7期59卷 1317-1328页

作者： LI Xue Ying ZHENG FengF eng CHEN Yu Fei GUO Wen Ting ZHANG TingT ing HU AnY i YU Chang Ping ZHANG Chuan Lun State Key lab of Marine Geology Tongji University Key lab of Urban Pollutant Conversion Institute of Urban Environment Chinese Academy of Sciences

Archaea play an important role in global carbon and nitrogen cycles. Archaeal lipids, such as isoprenoid glycerol diakyl glycerol tetraethers(i GDGTs), are important biomarkers tracing change in archaeal community structure and biogeochemical processes in the natural environments. In this research, the spatial distributions of archaeal lipids in the surface sediments of the Jiulong River(JR) and the Jiulong River estuary(JRE) were examined. GDGT-0(containing zero cyclopentyl ring) and crenarchaeol were the most abundant i GDGTs in the JR and JRE. From the rivers to the estuary, the total i GDGTs, GDGT-0, crenarchaeol and archaeol concentrations showed significant spatial variation; in particular, GDGT-0 and archaeol in the river may be predominantly derived in situ from methanogens, whereas crenarchaeol in the estuary mainly derived in situ from Thaumarchaeota. We inferred that archaeal community was dominated by methanogens in the Jiulong River and by Thaumarchaeota in the Jiulong River estuary, which are consistent with change in archaeal community structure observed in other estuarine environments.

关键词： GDGT-0 Crenarchaeol Archaeol Spatial distribution Jiulong River Jiulong River Estuary

pH-metric and thermodynamic studies of rare earth metal chelates

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2009年第3期27卷 457-460页

作者： Alok Vyas R. P. Mathur The Werner lab Department of ChemistryDungar College

Proton ligand stability constants of hydroxybenzoic acid containing nitro group （2-Hydroxy-4-nitrobenzoic acid and 3-Hydroxy-4- nitrobenzoic acid） were determined through lrving-Rossoti pH titration technique. The stability constants of rare earth metal chelates containing 2-Hydroxy-4-nitrobenzoic acid and 3-Hydroxy-4-nitrobenzoic acid as ligands were studied in aqueous medium at different ionic strength （p=0.01, 0.05 and 0.1 mol/L） and temperatures （298, 308 and 318± 0.1 K）. The values of stability constant were evaluated through different computational methods like successive approximation, least square treatment, correction term method, and convergence method. The observed value of thermodynamic parameters （△G°, △H° and △S°） favors the complex formation between metal and ligands. The order of stabifity constant was found to be Pr（III）〈Nd（III）〈Sm（III）〈Tb（III）〈Ho（III）〈Er（III） as reported by Stagg and Powell.

关键词： hydroxy nitrobenzoic acid rare earth metal chelates Irving-Rossoti method

Chemical Kinetic Aspects of Solid State Reaction Producing Wollastonite from Rice Husk Silica and Limestone

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2001年第2期17卷 243-246页

作者： M.S.Nizami PCSIR laboratories Complex, Lahors, Pakistan M.Z.Iqbal Punjab University, Institute of Chemistry, Lahors, Pakistan PCSIR lab. Complex Lahore Pakistan

An industrial mineral wollastonite (CaSiO3) was produced under solid state conditions from rice husk silica and limestone. Reaction was carried out at 900'C to 1300'C for 1 h. The product batches were subjected to XRD and chemical analysis techniques specific for wollastonite. Mole fractions of different product batches were calculated on the basis of accumulated data to study the kinetics. Specific rate constants and reaction rate were also found out. Various probable models of mechanism for reaction were considered and testified with the laid down criterion for suggesting the suitable one. The resulting data were treated with Arrhenius equation as well and activation energy was calculated--therefrom. In addition to finding it's value from the slope of Arrhenius curve, an alternate method was also applied for this purpose. Both of the values were observed to be comparable. The activation energy required for performed reaction was found to be almost one third of that reported for synthesizing CaSiO3 by using quartz. This referred to the economical preparation of wollastonite by using rice husk as a source of silica instead of quartz.

关键词： Chemical Kinetic Aspects of Solid State Reaction Producing Wollastonite from Rice Husk Silica and Limestone rate

Structural transformation and rheological processes in bulk metallic glass Zr_(41)Ti_(14)Cu_(12.5)Ni_(10)Be_(22.5)

在线全文

学校读者我要写书评

暂无评论

中国有色金属学会会刊：英文版 2004年第2期14卷 218-222页

作者：王敬丰蒲健邹辉甘章华柳林肖建中 State Key lab of Die and Mould Technology

The temperature dependence of strain and strain rate of the Zr41Ti14Cu12.5Ni10Be22.5（Vit1） bulk metallic glass （BMG） under constant heating condition was derived from the static extension method with a dynamic thermal mechanical analyzer （DMA）. A few strain rate peaks, which corresponds to the glass transition and multistep crystallization in the differential scanning calorimeter （DSC） examination, were observed in the curves of the relation between strain rate and temperature. The onset of viscous flow and the end of glass transition are interrelated, the first and second strain rate peaks correspond with the first and second crystallization transition processes, respectively. The influence of stress on strain and strain rate was researched. It is found that the rheological behaviour of BMG Vit1 changes from elasticity to anelasticity, finally to the Newtonian viscous flow along with increasing temperature.

关键词： Zr41Ti14Cu12.5 锆合金大块金属玻璃流变学结构转变 BMG DMA DSC

Dynamics of 3-DOF Hybrid Robot Manipulator

在线全文

学校读者我要写书评

暂无评论

Journal of Donghua University(English Edition) 2004年第4期21卷 108-112页

作者：周兵毛泰祥杨汝清 Robot lab Shanghai Jiaotong University Shanghai 200030Dr Robot lab Shanghai Jiaotong University Shanghai 200030 Robot lab

This paper introduces a 3-dof hybrid robotic manipulator which is constructed by combining a parallel mechanism and a pantograph to increase stiffness as well as workspace. And by analyzing its kinematics and dynamics with Lagrange’s method, the dynamic model is obtained which is essential for feed-forward control of the manipulator. An explicit solution is given out. Finally, a simulation test is carried out on computers.

关键词： Hybrid robotic mechanism Dynamics computer simulation.

Scheduling Reconfigurable Service Function Chain

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Electronics 2019年第6期28卷 1244-1249页

作者： ZHU Kai WU Chunming ZHOU Boyang College of Computer Science Zhejiang University Zhejiang lab

Network function virtualization(NFV),has been widely adopted in existing networks since it brings lower capital expenditure and operating expense,as well as flexible and elastic deployment. Based on NFV, dynamic Service function chain(SFC) provides more comprehensive and thorough traffic steering over a series of middleboxes, e.g., DPI, and IDS. Nevertheless, dynamic SFC involves internal state migration in middleboxes, making it hard to allocate SFC *** propose a reconfigurable SFC scheduling approach with consideration on resource constraints and race of the state migration to collaborate the execution of the SFC reconfiguration, in the reasonable fashion based on a heuristic algorithm. The evaluation is conducted through discrete event simulation to validate the efficiency of our reconfigurable SFC scheduling, and the results demonstrate that the proposed method outperforms First Come First Serve scheduling and random scheduling.

关键词： Network function virtualization(NFV) Service function chain(SFC) State migration SDN