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EXPERIMENTAL RESEARCh OF CYLINDER TO BED hEAT TRANSFER IN AGITATED FLUIDIZED BEDS

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journal of hydrodynamics 2000年第4期12卷 36-40页

作者： Ma, j.h. Dep. of Air-condition Eng. Shandong Inst. of Archit. and Eng. Jinan 250014 China

Cylinder-to-bed heat transfer in agitated fluidized beds was studied experimentally. In the experiments, the aluminum particles were used as bed material, the diameter of those ranged from 0.5 mm to 2 mm. The effects of gas velocity, particles size, and agitator rotary speed on heat transfer were studied. From the experimental results, we have come to the following conclusion: (1) there are optimal ranges for airflow velocity and rotary speed to get optimal heat transfer coefficient; (2) the cylinder-to-bed heat transfer is greatly affected by gas velocity, rotary speed and particles sizes, and the effect of rotary speed on heat transfer is similar to that of gas velocity; (3) higher heat transfer coefficient is obtained with smaller particles.

关键词： Fluidized beds heat transfer Mass transfer Two phase flow

Ab initio STUDIES ON MAGNETISM OF 3d TRANSITION METAL DIMERS

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Acta Metallurgica Sinica(English Letters) 2007年第5期20卷 341-346页

作者： j.h. Gu Z.L. Zhu School of Physical Engineering and Material Physics Laboratory Zhengzhou University Zhengzhou 450052 China

Ab initio calculations with the self-consistent full-potential linearized augmented-plane-wave method （FLAPW）, under generalized gradient approximation, have been carried out to describe the electronic and magnetic properties of 3d transition metal dimers. It predicted the antiferromagneticity of Cr2 and ferromagneticity of other species. The Mn2 dimer was shown to be ferromagnetic coupling with a local magnetic moment of 5μB. retaining the value of its free atom state. The V2 and Ni2 exhibited low spin-polarization with local magnetic moment of only 1μB per atom. On the other hand, Fe2 and Co2 were highly spin-polarized with local magnetic moments of 3 and 2μB.

关键词： magnetism 3d transition metal dimer ab initio calculation

Electromagnetoelastic behaviors of functionally graded piezoelectric solid cylinder and sphere

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Acta Mechanica Sinica 2007年第1期23卷 55-63页

作者： h. L. Dai Y.M. Fu j.h. Yang Department of Engineering Mechanics Hunan University Changsha 410082 China

Analytical studies on electromagnetoelastic behaviors are presented for the functionally graded piezoelectric material （FGPM） solid cylinder and sphere placed in a uniform magnetic field and subjected to the external pressure and electric loading. When the mechanical, electric and magnetic properties of the material obey an identical power law in the radial direction, the exact displacements, stresses, electric potentials and perturbations of magnetic field vector in the FGPM solid cylinder and sphere are obtained by using the infinitesimal theory of electromagnetoelasticity. Numerical examples also show the significant influence of material inhomogeneity. It is interesting to note that selecting a specific value of inhomogeneity parameter β can optimize the electromagnetoelastic responses, which will be of particular importance in modern engineering designs.

关键词： Functionally graded piezoelectric material (FGPM) Electromagnetoelastic Solid cylinder Solid sphere Perturbation of magnetic field vector

DRYING OF GRANULAR MATERIALS IN AGITATED FLUIDIZED BED

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journal of hydrodynamics 2001年第2期13卷 29-31页

作者： Ma, j.h. Liu, h. Feng, D.Z. Dept. of Air-Condition Eng. Shandong Inst. of Civil Eng. Jinan 250014 China

An experimental study of the drying characteristics of an agitated fluidized bed dryer is presented and discussed. In the study, the citric acid particles were used as bed material with the diameters ranging from 0.2 mm to 1.3 mm. The variables affecting apparently the drying rate were found to be the mass flow rate, the inlet air temperature, the rotary speed of agitating mechanism and the particles feed rate. Comparing with other variables considered, mass flow rate was found to have the least important influence on the drying rate. The agitated fluidized bed dryer is suitable to drying agglomerating or sticky materials.

关键词： Dryers (equipment) Drying Experiments Mass transfer

STUDY ON PTA CLAD (Cr,Fe)_7C_3/γ-Fe CERAMAL COMPOSITE COATING

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Acta Metallurgica Sinica(English Letters) 2005年第6期18卷 695-700页

作者： j.B. Liu j.h. huang L.M. Wang Department of Mechanical and Electronic Engineering Weifang University Weifang 261061 China School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China

A wear resistant （Cr, Fe）7C3/γ-Fe ceramalcomposite coating wasfabricatedon substrate of a 0.45% C carbon steel by plasma transferred arc （PTA） cladding process using the Fe-Cr-C elemental powder blends. The microstructure, microhardness and dry sliding wear resistance of the coating were evaluated. Results indicate that the plasma transferred arc clad ceramal composite coating has a rapidly solidified microstructure consisting of blocky primary （Cr, Fe）7C3 and the interblocky （ Cr, Fe）7C3/γ-Fe eutectics and is metallurgically bonded to the 0.45%C carbon steel substrate. The ceramal composite coating has high hardness and excellent wear resistance under dry sliding wear test condition.

关键词： plasma transferred arc ( PTA ) cladding ( Cr Fe )7C3/γ-Fe coating,microstructure wear

Computational Analysis of a Variable Ejector Flow

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journal of Thermal Science 2006年第2期15卷 140-144页

作者： h.D. KIM j.h. LEE T. SETOGUChI S.MATSUO School of Mechanical Engineering Andong National University 388 Songchun-dong Andong 760-749 Korea Department of Mechanical Engineering Saga University 1 Honjo Saga 840-8502 Japan

The present study addresses a variable ejector which can improve the ejector efficiency and control the re-circulation ratio under a fixed operating pressure ratio. The variable ejector is a facility to obtain specific recirculation ratio under a given operating pressure ratio by varying the ejector throat area ratio. The numerical simulations are carried out to provide an understanding of the flow characteristics inside the variable ejector. The sonic and supersonic nozzles are adopted as primary driving nozzles in the ejector system, and a movable cone cylinder, inserted into a conventional ejector-diffuser system, is used to change the ejector throat area ratio. The numerical simulations are based on a fully implicit finite volume scheme of the compressible, Reynolds-Averaged Navier-Stokes equations. The results show that the variable ejector can control the recirculation ratio at a fixed operating pressure ratio.

关键词： variable ejector ejector throat area ratio re-circulation ratio

NUMERICAL MODELING OF DONGZhUANG RESERVOIR ON jING RIVER

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journal of hydrodynamics 2001年第2期13卷 68-71页

作者： Yang, M. Zhang, h.Y. Zhang, j.h. Zhang, h.W. Dept. 5 Beijing Univ. of Aero. and Astron. Beijing 100084 China

The Dongzhuang Reservoir will be constructed on the jing River, which is laden with the highest sediment concentration in the world. The sediment problem is a key challenge for the reservoir design and management. This paper presents essential data, details of sediment scour and siltation calculated by the numerical modeling based on new fundamental equations. Calculated results prove that the reservoir could preserve long-term storage capacity with the operation was offered by the design department.

关键词： Flow of fluids Mathematical models Sediments Storage (materials)

Study on Ship Automatic Berthing System with Mooring Lines

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China Ocean Engineering 2017年第1期31卷 19-29页

作者： K.U.Yang j.G.hur M.S.Choi D.j.Yeo j.h.byun Department of Power System Engineering Chonnam National UniversityYeosu 550-749Korea College of Fisheries and Ocean Science Chonnam National UniversityYeosu 550-749Korea Departrnent of Maritime Police Science Chonnam National UniversityYeosu 550-749Korea

This study describes an automatic berthing system with mooring lines. It is designed to be berthed by using mooring device on the upper deck of a ship. It is to berth once maintaining parallel with the quay by controlling both forward and aft breast lines. Berthing method is used through length adjustment of mooring lines connected between ship and quay by controlling the angular velocity and the torque of hydraulic motor in mooring device. The study is conducted under three changing conditions of draft, such as even-keel, rise of the gravity center and trim to stern. Variables affecting berthing stability are determined based on the control performance of each condition. Bond graphs method is used to model the system. Controller is designed as PID control method of reference-model algorithm. The control program is composed of synchronous control system based on the equations derived with the numerical analysis. The tank test is conducted to verify the usefulness of the control program.

关键词： hydraulic maintain affecting berth torque adjustment draft attitude gravity verify

Carbide Formation Process in Directionally Solidified MAR-M247 LC Superalloy

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journal of Materials Science & Technology 1999年第1期15卷 48-52页

作者： Chen, jian huang, Baiyun Lee, j.h. Choe, S.j. Lee, Y.T. Cent S Univ Technol Powder Met Res Inst Changsha 410083 Peoples R China Changwon Natl Univ Dept Met & Mat Sci Changwon 641773 South Korea Korea Inst Machinery & Mat Changwon 641010 South Korea

Carbide nucleation, growth and trapping behavior in directionally solidified MAR-M247 LC alloy and the corresponding mechanism have been investigated. Carbide forming element enrichment controls the carbide nucleation and the carbide growth behavior. If the carbide forming element enrichment and the nucleation sites are suitable, carbide nucleation can occur both above and below the liquids temperature. heterogeneous carbide nucleation is the preferred nucleation mechanism at low carbide forming element enrichment. Carbide growth occurs mainly at inter-secondary gamma dendrite arm area and lower part of the mushy zone. The carbides are subsequently trapped at these positions after growing to a certain size. Some carbides are only partially trapped by the solid-liquid interface and the carbide growth accelerates after being partially trapped. A critical growth rate exists between 2 multiplied by 10** minus **6 m/s and 5 multiplied by 10** minus **6 m/s. The carbide volume fraction decreases in the directionally solidified part at slow growth rate which is caused by the lack of suitable growth site and the low trapping ability of the solid-liquid interface. (Edited author abstract) 16 Refs.

关键词： Nickel alloys