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Improving the performance of a thermoelectric power system using a flat-plate heat pipe

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Chinese Journal of Chemical Engineering 2019年第1期27卷 44-53页

作者： Suchen Wu Yiwen Ding Chengbin Zhang Dehao xu Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education School of Energy and EnvironmentSoutheast University Nanjing ACME Electronics Cooling Service Inc.

A gravitational flat-plate heat pipe is designed and fabricated in this paper to serve as a heat spreader to diffuse the local heat source to the hot side of the thermoelectric power *** on this, an experimental test for the thermoelectric power generation system is conducted to study the influences of the heat spreader on the temperature uniformity and power generation performance when exposing to a local heat *** addition,the effects of the heating power, inclination angle, and local heat source size on the power generation performance of the thermoelectric power module using a flat-plate heat pipe as a heat spreader are examined and compared with that using a metal *** results indicate that the gravitational flat-plate heat pipe has considerable advantages over the metal plate in the temperature *** superiority of temperature uniformity in the improvement of power generation performance for the thermoelectric power system using a heat pipe is ***, the heat pipe shows good adaptability to placement mode and the local heat source size, which is beneficial to the application in the thermoelectric power generation.

关键词： Thermoelectric Heat pipe Heat spreader Power generation

Nonlinear Dynamic Characteristics of the Vectored Thruster AUV in Complex Sea Conditions

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Chinese Journal of Mechanical Engineering 2011年第6期24卷 935-946页

作者： GAO Fudong PAN Cunyun xu Xiaojun ZHANG Xiang College of Mechatronic Engineering and Automation National University of Defense TechnologyChangsha 410073China

The mobility of the vectored thruster AUV in different environment is the important premise of control system design. The new type of autonomous underwater vehicle (AUV) equipped with rudders and vectored thrusters which are combined to control the course is studied. Firstly, Euler angles representation and quaternion method are applied to establish six-DOF kinematic model respectively, then Newton second law and Lagrangian approach are used to deduce the vectored thruster AUV’s nonlinear dynamic equations with six degrees of freedom (DOF) respectively in complex sea conditions based on the random wave theory according to the structural and kinetic characteristics of the vectored thruster AUV in this paper. The kinematic models and dynamic models based on different theories have the same expression and conclusion, which shows that the kinematic models and dynamic models of the vectored thruster AUV are accurate. The Runge-Kutta arithmetic is used to solve the dynamic equations, which not only can simulate the motions such as cruise and hover but also can describe the vehicle’s low-frequency and high-frequency motion. The results of computation show that the mobility of the vectored thruster AUV in interference-free environment and the integrated signals including low-frequency motion signal and high-frequency motion signal in environmental disturbance accord with practical situation, which not only solve the problem of especial singularities when the pitch angle θ = ±90° but also clears up the difficulties of computation and display of the coupled nonlinear motion equations in complex sea conditions. Moreover, the high maneuverability of the vectored thruster AUV equipped with rudders and vectored thrusters is validated, which lays a foundation for the control system design.

关键词： complex sea conditions vectored thruster autonomous underwater vehicle nonlinear dynamic characteristics

Dynamic recrystallization behavior of GH4169G alloy during hot compressive deformation

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Journal of Materials Science & Technology 2019年第9期35卷 1851-1859页

作者： Dan Jia Wenru Sun Dongsheng xu Fang Liu University of Chinese Academy of Sciences Beijing100049China Institute of Metal Research Chinese Academy of SciencesShenyang110016China

The microstructure evolutions and nucleation mechanisms of GH4169G alloy were studied by optical microscope, electron backscatter diffraction (EBSD) and transmission electron microscope (TEM). The hot compression tests were performed different imposed reductions in the range of true strain from 0.12 to 1.2 at the temperatures of 930 °-1050 ° with strain rates of 0.01 s^-1-l s^-1. It is found that cumulative and local misorientation increase firstly and then decrease when the strain is increased due to the progress of dynamic recrystallization (DRX). The low angle boundaries (LAGBs) rapidly develop to high angle boundaries (HAGBs) at relatively high deformation temperature or the low strain rate. There are three DRX mechanisms observed for GH4169 G alloy during hot deformation. Discontinuous dynamic recrystallization (DDRX) as the dominant mechanism for GH4169 G alloy is characterized by typical necklace structures and bulged-original boundaries. Besides, different deformation bands with dislocation cells formed in deformed matrix at low temperature and large strain, which indicates that continuous dynamic recrystallization (CDRX) contributed to the DRX process. The twin boundaries lost their coherent characteristics and provide sites for nucleation, which also accelerates the nucleation of DRX.

关键词： GH4169G alloy Dynamic recrystallization Nucleation mechanism

Recent advances in “living”/controlled radical polymerization of phosphorus-containing monomers and their potential applications

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Science China Chemistry 2015年第11期58卷 1633-1640页

作者： Tianchi xu Lifen Zhang Zhenping Cheng Xiulin Zhu Suzhou Key Laboratory of Macromolecular Design and Precision Synthesis Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application Department of Polymer Science and Engineering College of Chemistry Chemical Engineering and Materials ScienceSoochow University

Special research attention has been paid to phosphorus-containing materials and their corresponding applications. This mini review considers recent publications devoted to the "living"/controlled radical(co)polymerization of phosphorus-containing monomers. In addition, different properties of the polymers involved in the phosphonate group in various chemical environments are demonstrated, and their potential applications are briefly discussed.

关键词： living radical polymerization nitroxide-mediated polymerization (NMP) atom transfer radical polymerization (ATRP) reversible addition-fragmentation chain transfer (RAFT) phosphorus-containing monomer

Reliability Evaluation of IEEE 802.11p-Based Vehicle-to-Vehicle Communication in an Urban Expressway

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Tsinghua Science and Technology 2015年第4期20卷 417-428页

作者： Yizhi Wang Jianming Hu Yi Zhang Chao xu Department of Automation Tsinghua National Laboratory for Information Science and Technology (TNList) Tsinghua University Jiangsu Province Collaborative Innovation Center of Modern Urban Traffic Technologies

IEEE 802.11p/DSRC （Dedicated Short Range Communication） is considered to be a promising wireless communication standard for enhancing transportation safety and efficiency. However, IEEE 802.11p-based Vehicle- to-Vehicle （V2V） communication is still unreliable because of the complicating factors of high vehicle speed and complex radio environments. In this paper, we performed a data-based evaluation of V2V communication reliability, using real-world measurements in a typical urban expressway in Beijing. With respect to the characteristics of the urban expressway and our experimental data, we found road slope and traffic density to be the major environmental factors having a significant impact on the V2V communication＇s Line-Of-Sight （LOS） conditions. On the basis of these two factors, we propose a fuzzy classification method for the LOS conditions, and separate the real- time communication environments into different LOS cases. For each LOS case, we quantify the metrics as received signal strength indication, packet delivery rate, and communication latency. The results reveal that the communication reliability in urban expressways is very unstable because of the changing LOS conditions. This study provides a useful reference for the IEEE 802.11 p-based cooperative systems in urban expressways.

关键词： IEEE 802.11p V2V communication empirical measurement urban expressway line-of-sight condition

An elastic model for bioinspired design of carbon nanotube bundles

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Acta Mechanica Sinica 2015年第2期31卷 205-215页

作者： Xiaoyu Sun Zuoqi Zhang Yuanjie xu Yongwei Zhang School of Civil Engineering Wuhan University Institute of High Performance Computing A*STARSingapore 138632Singapore

Collagen fibers provide a good example of making strong micro-or mesoscale fibers from nanoscale tropocollagen molecules through a staggered and crosslinked organization in a bottom-up *** the architectural features of collagen fibers has been shown to be a promising approach to develop carbon nanotube（CNT）fibers of high *** the present work,an elastic model is developed to describe the load transfer and failure propagation within the bioinspired CNT bundles,and to establish the relations of the mechanical properties of the bundles with a number of geometrical and physical parameters such as the CNT aspect ratio and longitudinal gap,interface cross-link density,and the functionalizationinduced degradation in CNTs,*** the model,the stress distributions along the CNT-CNT interface as well as in every individual CNT are well captured,and the failure propagation along the interface and its effects on the mechanical properties of the CNT bundles are *** work may provide useful guidelines for the design of novel CNT fibers in practice.

关键词： Carbon nanotube fiber Collagen-mimic design Staggered pattern Interface modification

Changes in groundwater levels and the response of natural vegetation to transfer of water to the lower reaches of the Tarim River

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Journal of Environmental Sciences 2007年第10期19卷 1199-1207页

作者： xu Hai-liang YE Mao LI Ji-mei Xinfiang Institute of Ecology and Geography Research Chinese Academic of Science Urumqi 830011 China School of Geography Sciences and Touristy Xinfiang Normal University Urumqi 830054 China

Restoration and reconstruction of the degraded Tarim River ecosystem is an important challenge. A goal of an ecological water conveyance project is to protect and restore the natural vegetation in the lower reaches of Tadm River by transferring water from Bosten Lake, through the river channel, to the lower reaches. This study describes the changes in groundwater depth during the water transfer and the respondence of riparian vegetation to alterations in groundwater levels. The results indicate that groundwater depth along the Tarim River channel has a significant spatial-temporal component. Groundwater levels closest to the river channel show the most immediate and pronounced changes as a response to water transfer while those further away respond more slowly, although the observed change appears to be longer in duration. With a rise in the groundwater level, natural vegetation responded with higher growth rates, biomass and biodiversity. These favorable changes show that it is feasible to protect and restore the degraded natural vegetation by raising the groundwater depth. Plant communities are likely to reflect the hysteresis phenomenon, requiting higher water levels to initiate and stimulate desired growth than what may be needed to maintain the plant community. Because different species have different ecologies, including different root depths and densities and water needs, their response to increasing water availability will be spatially and temporally heterogenous. The response of vegetation is also influenced by microtopography and watering style. This paper discusses strategies for the protection and restoration of the degraded vegetation in the lower reaches of the Tarim River and provides information to complement ongoing theoretical research into ecological restoration in add or semi-arid ecosystems.

关键词： the lower reaches of Tarim River ecological watering conveyance groundwater depth ecological response natural vegetation

Cathodic reduction process of Al-Cu-Y alloy in fluoride-oxide eutectic system via molten salt electrolysis

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Journal of Rare Earths 2018年第3期36卷 324-330页

作者： xu Wang Chunfa Liao Yunfen Jiao Hao Tang School of Metallurgy and Chemical Engineering Jiangxi University of Science and Technology

Al-Cu-Y alloys were prepared by molten salt electrolysis in fluoride-oxide system composed of electrolyte（Na3 AlF6-AlF3-LiF-MgF2） and oxide（Al2 O3-CuO-Y2 O3）. Cathodic reduction process of Al2 O3,CuO and Y2 O3 were analyzed by cyclic voltammetry and chronoamperometry. Components and phase composition of alloy samples prepared by potentiostatic electrolysis were characterized by scanning electron microscopy and energy dispersive spectroscopy. The results show that the Al-Cu-Y alloy can be prepared in the AIF3-NaF-5 wt%LiF-5 wt%MgF2（NaF/AlF3 = 2.2, molecular ratio） eutectic system with mixed oxide（Al2 O3-CuO-Y2 O3） through 2 h at the conditions of a temperature of 1208 K, cell voltage3.0 V, cathode current density 0.7 A/cm^2. Al（Ⅲ） and Cu（Ⅱ） ions can be reduced to zero valence Al（0） and Cu（0） directly on carbonaceous electrode surface by instantaneous nucleation, respectively, the reduction process is controlled by diffusion. The reduction potential of Y（Ⅲ） ions is close to the active ions of fluoride melts, but strengthened phase AI3 Y can be formed through electrochemical reduction and alloyed process with active Al（Ⅲ） and Cu（Ⅱ） ions, meanwhile, the Al2 Cu and Al3 Y phases are distributed at the grain boundary of Al matrix.

关键词： Fluoride-oxide eutectic Al-Cu-Y alloy Molten salt electrolysis Cyclic voltammetry Electrode process Rare earths

Blade bowing effects on radial equilibrium of inlet flow in axial compressor cascades

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Chinese Journal of Aeronautics 2017年第5期30卷 1651-1659页

作者： Han xu Hao CHANG Donghai JIN Xingmin GUI School of Energy and Power Engineering Beihang University Beijing 100083 China AECC Shenyang Engine Research Institute Shenyang 110015 China

The circumferentially averaged equation of the inlet flow radial equilibrium in axial compressor was deduced. It indicates that the blade inlet radial pressure gradient is closely related to the radial component of the circumferential fluctuation（CF） source item. Several simplified cascades with/without aerodynamic loading were numerically studied to investigate the effects of blade bowing on the inlet flow radial equilibrium. A data reduction program was conducted to obtain the CF source from three-dimensional（3D） simulation results. Flow parameters at the passage inlet were focused on and each term in the radial equilibrium equation was discussed quantitatively. Results indicate that the inviscid blade force is the inducement of the inlet CF due to geometrical asymmetry. Blade bowing induces variation of the inlet CF, thus changes the radial pressure gradient and leads to flow migration before leading edge（LE） in the cascades. Positive bowing drives the inlet flow to migrate from end walls to mid-span and negative bowing turns it to the reverse direction to build a new equilibrium. In addition, comparative studies indicate that the inlet Mach number and blade loading can efficiently impact the effectiveness of blade bowing on radial equilibrium in compressor design.

关键词： Axial compressor Bowing Cascade Circumferential fluctuation Inlet flow Radial equilibrium