检索结果-南通市图书馆

Simulation of Unsteady State Performance of a Secondary Air System by the 1D-3D-Structure Coupled Method

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2016年第1期25卷 68-77页

作者： WU Hong li Peng li yulong National Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics Beihang University

This paper describes the calculation method for unsteady state conditions in the secondary air systems in gas turbines. The 1D-3D-Structure coupled method was applied. A 1D code was used to model the standard components that have typical geometric characteristics. Their flow and heat transfer were described by empirical correlations based on experimental data or CFD calculations. A 3D code was used to model the non-standard components that cannot be described by typical geometric languages, while a finite element analysis was carried out to compute the structural deformation and heat conduction at certain important positions. These codes were coupled through their interfaces. Thus, the changes in heat transfer and structure and their interactions caused by exterior disturbances can be reflected. The results of the coupling method in an unsteady state showed an apparent deviation from the existing data, while the results in the steady state were highly consistent with the existing data. The difference in the results in the unsteady state was caused primarily by structural deformation that cannot be predicted by the 1D method. Thus, in order to obtain the unsteady state performance of a secondary air system more accurately and efficiently, the 1D-3D-Structure coupled method should be used.

关键词： Secondary air system Unsteady 1D-3D-structure Coupling Gas turbine

Experimental investigation on the yield behavior of metal foam under shear-compression combined loading

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2021年第7期64卷 1412-1422页

作者： LUO Geng XUE Pu li yulong School of Automobile Chang’an UniversityXi’an710064China School of Aeronautics Northwestern Polytechnical UniversityXi’an710072China Joint International Research Laboratory of Impact Dynamics and its Engineering Applications Northwestern Polytechnical UniversityXi’an710072China

Metal foams are typically subjected to quasi-static or dynamic shear-compression combined loading in applications such as energy absorbers and structure protectors. The yield behavior of a metal foam under dynamic and quasi-static shear-compression combined loadings is investigated in this study. First, quasi-static and dynamic compression-shear combined tests at different loading angles are conducted using a universal testing machine and a rotatable Hopkinson bar system, respectively. Shear deformation reduces the plateau stress as the loading angle increases. Subsequently, the yield modes of the metal foam under combined loadings are investigated. Only one yield band occurs under a combined loading with large loading angles(mode I),whereas several yield bands occur under a combined loading with small loading angles(mode II). Finally, the yield surface plot of metal foam indicates significant enhancement in terms of normal stress and shear stress under dynamic loading. Quasi-static and dynamic phenomenological yield criteria for a shear-normal stress space are established to provide a brief and precise prediction of the behavior of metal foam under quasi-static and dynamic combined loadings.

关键词： metal foam yield behavior shear-compression combined loading yield mode yield criterion

A NOVEL APPROACH TO TESTING THE DYNAMIC SHEAR RESPONSE OF Ti-6Al-4V

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Solida Sinica 2012年第3期25卷 299-311页

作者： Yazhou Guo yulong li School of Aeronautics Northwestern Polytechnical UniversityXi'an 710072China

Modifications were made on the traditional split Hopkinson pressure bar （SHPB） system to conduct dynamic shear tests. The shear response of Ti-6A1-4V was acquired at a shear strain rate of 104 s-1 by using this modified apparatus. The geometry as well as the clamping mode of the double-notch specimen was optimized by commercial FEM software ABAQUS, and the feasibility of the experiment set-up was validated. A shear stress calibration coeff^cient of γT = 1.03 and a shear strain calibration coefficient of γT- = 0.50 were *** have employed high- speed photography to record the deformation process, especially the initiation and propagation of adiabatic shear band （ASB）, during the dynamic shear test. The frames show that the time duration from ASB initiation to its completion is less than 2 μs, from which we can estimate that the propagation speed of ASB within Ti-6A1-4V is more than 1250 m/s under such loading conditions. The temperature rise within ASB is also estimated to be △T2 ≈ 1460 ℃ based on energy balance. Such high temperature has led to softening of the material within the ASBs, and has intensified the shear localization and finally resulted in fracture of the material.

关键词： dynamic shear adiabatic shear band ASB double notch SHPB Ti-6A1-4V

New imaging methods for monitoring dopaminergic neurotransmission

在线全文

学校读者我要写书评

暂无评论

Science China(life Sciences) 2022年第4期65卷 838-841页

作者： Yizhou Zhuo yulong li State Key Laboratory of Membrane Biology Peking University School of Life SciencesBeijing100871China PKU-IDG/McGovern Institute for Brain Research Beijing100871China PKU-THU Center for life Sciences Academy for Advanced Interdisciplinary StudiesPeking UniversityBeijing100871China

Dopamine is a crucial monoamine neuromodulator,which is primarily synthesized in the ventral midbrain in the central nervous system and activates G protein-coupled dopamine receptors to modulate the neuronal circuit d... 详细信息

关键词： dynamics dopamine Dopamine

Analysis of an Evaporator-condenser-separated Mechanical Vapor Compression System

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2013年第2期22卷 152-158页

作者： Wu Hong li yulong Chen Jiang School of Jet propulsion Beihang University

An evaporator-condenser-separated mechanical vapor compression (MVC) system was presented. The better effect of descaling and antiscaling was obtained by the new system. This study focused on the method of thermodynamic analysis, and the energy and exergy flow diagrams were established by using the first and second law of thermodynamics analysis. The results show that the energy utilization rate is very high and the specific power consumption is low. Exergy analysis indicates that the exergy efficiency is low, and the largest exergy loss occurs within the evaporator-condenser and the compressor.

关键词： Mechanical vapor compression Sewage treatment Thermodynamic Exergy

Micro gas turbine:Developments,applications,and key technologies on components

在线全文

学校读者我要写书评

暂无评论

Propulsion and Power Research 2023年第1期12卷 1-43页

作者： Jingqi li yulong li National Key Laboratory of Science and Technology on Aero Engines Aero-thermodynamics&Collaborative Innovation Center for Advanced Aero-Engine School of Energy and Power EngineeringBeihang UniversityBeijing 100191China

Owing to their precedent characteristics,micro gas turbines(MGTs)have been favored as popular power machinery in plenty of energy systems such as distributed energy systems,range extenders,solar power generations,fuel cell systems and individual power *** specific features essentially include but are not limited to strong fuel adaptability,low emissions,flexible structure,and easy *** the past 20 years,various types of MGTs have been *** and forward-looking technologies have been employed in the design and production of MGTs and their *** them,fully radial flow structures,gas lubricated bearings and efficient recuperators are typical approaches to enhance the overall performance and compactness,however,the exploitation of ceramic based materials and intelligent algorithms in component design can also assist in improving the *** applications of MGTs have been expanded to many fields,and the research on related components has also made new *** to the time frame,there is no systematic summary of the latest relevant research,so it is essential to have a comprehensive understanding of the applications of MGTs and their pertinent *** paper aims to present a comprehensive review on MGTs,covering the development status,applications,factors of performance and representative explorations of their *** investigations regarding the characteristics of commercial MGTs are also *** in distributed energy,range extenders,solar generations,and fuel cell systems are distinctly *** research work on compressors,turbines,combustors,recuperators,and rotor systems are reviewed and *** technologies and methods associated with materials,manufacturing,and cycles beneficial to the future development of MGTs are also explained and discussed in some detail.

关键词： Distributed generation Micro gas turbines(MGTs) Compressor Turbine Optimization

Selective Laser Melting of Ti Composites: Latest Developments

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

材料导报 2019年第5期33卷 729-730页

作者： DONG Yangping li yulong YAN Ming Shenzhen Key Laboratory for Additive Manufacturing of High-performance Materials Department of Materials Science and Engineering Southern University of Science and Technology Mechanical & Electrical Engineering School Nanchang University

Ti and Ti alloys are wonderful metal materials,showing excellent corrosion resistance,high specific strength and outstanding biocompatibility[1-2].They have been widely used in a variety of industries,including aerospace engineering,biomedical enginee-ring,off-shore drilling,automobile industry and even jewelry industry[1-2].To further improve their performance for satisfying the ever increasing challenging demands,Ti-based metal matrix composite becomes a cutting-edge research direction[3-4].However,intrinsic properties of most Ti materials,such as low thermal conductivity,high chemical reactivity and hexagonal close packed crystal structure,make their machining rather difficult and also push up the cost of using Ti *** reinforcement phases of Ti are often hard-and-refractory ceramic particles,it is even harder to fabricate Ti composite using conventional fabrication methods[1-4].

关键词： Titanium matrix composite The laser Aerospace engineering

Numerical Investigation of Jet Impingement Cooling with Supercritical Pressure Carbon Dioxide in a Multi-Layer Cold Plate during High Heat Flux

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2023年第1期32卷 237-253页

作者： WEN Yaming li yulong li Jingqi YU Xin-Gang National Key Laboratory of Science and Technology on Aero Engines Aero-Thermodynamics&Collaborative Innovation Center for Advanced Aero-Engine School of Energy and Power EngineeringBeihang UniversityBeijing 100191China Beijing Institute of Spacecraft System Engineering Beijing 100094China

Jet impingement cooling with supercritical pressure carbon dioxide in a multi-layer cold plate during the heat flux of 400 W/cm_(2) is investigated *** generation and distribution of pseudocritical fluid with the high specific heat of supercritical pressure carbon dioxide and the mechanism of the heat transfer enhancement led by the high specific heat are *** a given nozzle diameter,the effects of the geometric parameters of a multi-layer cold plate such as the relative nozzle-to-plate distance,relative plate thickness,and relative upper fluid thickness on the average heat transfer coefficient are *** results show that the target surface is cooled effectively with supercritical pressure carbon dioxide jet impingement *** the radial distance is less than 6 mm,the maximum wall temperature is 368 K,which is 30 K lower than the maximum junction temperature for a silicon-based insulated gate bipolar transistor,a typical electronic power *** is a pseudocritical fluid layer near the target surface,where specific heat reaches above 34 kJ/(kg·K)*** drastic rise of the specific heat leads to obvious heat transfer *** a certain range,the local heat transfer coefficient and the specific heat are linearly correlated and Stanton number remains constant over this *** heat transfer coefficient is at a maximum when the relative nozzle-to-plate distance is *** the relative plate thickness increases from 0.5 to 3.5 or the relative upper fluid thickness increases from 0.5 to 2.5,the average heat transfer coefficient decreases monotonically.

关键词： high heat flux jet impingement cooling supercritical pressure carbon dioxide heat transfer enhancement

Spine maturation and pruning during development: Cadherin/Catenin complexes come to help

在线全文

学校读者我要写书评

暂无评论

Science China(life Sciences) 2015年第9期58卷 929-930页

作者： QIAN Cheng li yulong State Key Laboratory of Membrane Biology Peking University School of Life Sciences PKU-IDG/Mc Govern Institute for Brain Researchand Peking-Tsinghua Center for Life Sciences School of life Sciences PTN Joint Graduate Program Tsinghua University

Structural and functional alterations of synaptic connections underlay experience-dependent neuronal plasticity and are crucial for many brain functions, including learning and memory. Their defects, on the other hand, have been asso- ciated with neurological disorders such as autism. Although the molecular mechanism underlying long-term functional alterations of synaptic connections, including LTP and LTD, are becoming increasingly clear, the molecular mechanism for structural plasticity, such as spine pruning, remains largely unknown, especially in vivo.

关键词：蛋白复合物钙粘蛋白开发过程修剪神经可塑性成熟脊柱神经系统疾病