Volume 32,Issue 4,2009 Table of Contents

1 The effect of Ce addition on Ascast microstructures of AZ31 magnesium alloy

PAN Fusheng , PENG Jiaxing , YANG Mingbo

2009, 32(4):363-366. DOI: 10.11835/j.issn.1000-582X.2009.04.001

[Abstract](7554) [HTML](0) [PDF 2.36 M](1261)

Abstract:
Various opinions still exist regarding the grain refinement of magnesium alloys resulting from Ce addition. We investigate effect of Ce addition on the ascast microstructures of AZ31 magnesium alloy. The research results indicate that adding from 0.5 wt% to 1.5 wt% Ce to AZ31 magnesium alloy does not effectively refine the alloy grains; instead, the opposite effect results, causing obvious grain coarsening. The coarsening trend is related to the amount of Ce. After adding 0.5 wt% Ce to AZ31 magnesium alloy, the average alloy grain size increases from 60 μm to 164 μm. Furthermore, increasing the amount of Ce added from 0.5 wt% to 1.5 wt% causes the average grain size to decrease gradually. The average grain size of AZ31 magnesium alloy with and additional 1.5 wt% Ce still exceeds that of the AZ31 magnesium alloy without additional Ce, however.

2 Microstructures and tensile properties of commercial AZ31B magnesium alloy sheets

HUANG Guangshengb , LI Hongchengb , ZHANG Leib , SONG Bob

2009, 32(4):367-370. DOI: 10.11835/j.issn.1000-582X.2009.04.002

[Abstract](1846) [HTML](0) [PDF 3.66 M](1214)

Abstract:
Uniaxial loading tests are performed on 0.8 mm thick sheets of commercial AZ31B magnesium alloy in the temperature range from room temperature to 400 ℃. The microstructures and tensile properties are studied. The results reveal that there are few twins in the deformation microstructures created when deformation occurres in temperatures ranging from room temperature to 100 ℃, and dynamic recrystallization take place at deformation temperatures exceeding 200 ℃. Commercial AZ31B magnesium alloy sheets have a preferable strength and ductility at room temperature. The ductility of the sheets is improved as the deformation temperature increases. Some characteristics of low temperature superplasticity or high strain rate superplasticity exist.

3 Optimization of a webbased query system for a magnesium alloy database

TANG Aitaob , HUANG Sia , WANG Jingfengb , LIU Bina

2009, 32(4):371-375. DOI: 10.11835/j.issn.1000-582X.2009.04.003

[Abstract](2127) [HTML](0) [PDF 1.21 M](1515)

Abstract:
Based on an existing magnesium alloy database, a query system is optimized by considering the design characteristics, and an integrated query system for this magnesium alloy database is developed to meet the demands of more users. The result shows that the new system improves the query efficiency of the magnesium alloy database, especially for queries concerning phase diagrams and the structure of magnesium alloys. This means that the new system provides users a more powerful and useful magnesium alloy database.

4 Intellectual prediction of a permeability index for blast furnaces

LIANG Dong , BAI Chenguang , WEN Liangyin , WANG Feng , LV Xuewei , ZHANG Shengfu

2009, 32(4):376-380. DOI: 10.11835/j.issn.1000-582X.2009.04.004

[Abstract](1639) [HTML](0) [PDF 1.36 M](1879)

Abstract:
The permeability index for blast furnaces is an important monitoring parameter in their operation. Proper trend prediction of the permeability index is important for good operation. Support vector machines (SVM) combined with wavelet analysis are adopted to build a forecasting model. Four historic values of a permeability index are analyzed by a wavelet analysis via seven levels. Based on eight wavelet analyzed values and combined with operating parameters, eight submodels are built using the least square support vector machines method. The prediction components are reconstructed to obtain a forecast. The details of modeling, validation and result analyses are presented.

5 A mathematical description of the liquid flows inside blast furnaces

WANG Chengshan , XIAO Xingguo , WANG Wenzhong

2009, 32(4):381-386. DOI: 10.11835/j.issn.1000-582X.2009.04.005

[Abstract](1316) [HTML](0) [PDF 1.52 M](1221)

Abstract:
The knowledge of liquid flows in blast furnaces may play an important role in controlling the blast furnace process. Appropriate assumptions are given to represent the main characteristics of the liquid flow in blast furnaces, such as liquid streams being composed of unwetting liquid droplets, inertial force having little effect on the liquid flows, and mass exchange existing along the direction perpendicular to liquid flow. A mathematical model is built to predict the distribution of the liquid flow rate and the liquid flow range in packed beds. The scale of the numerical grid used to solve this model may not necessarily be reduced to the particle level. The predicted results of this model accord well with the observed data. This model is an alternative theory for the simulation of blast furnaces

6 Threedimensional temperature field visualization reconstruction of charge coupled device radiation image

ZHANG Xinglan , OUYANG Qi , HUANG Jiping

2009, 32(4):387-391. DOI: 10.11835/j.issn.1000-582X.2009.04.006

[Abstract](2708) [HTML](0) [PDF 1.87 M](1644)

Abstract:
Aiming at the questions of raceway section twodimension temperature distribution from twodimensional image accumulated by threedimensional radiation space and threedimensional temperature reconstruction error caused by limited charge coupled device (CCD) sensors for a sudden spread combustion chamber, the twodimension rectangle interpolation virtual CCD sensor installation algorithm is provided as a new technology for solving the difficulties of installing more CCD sensors and filtered back projection reconstruction error caused by limited projection numbers. The radiation intensity projection data got from flame image collected from the installed CCD sensors and computed virtual CCD sensors is interpolated for filtered back projection to computer intensity distribution and calibrated bicolor method is used to calculation temperature in raceway depth direction. The results of experiments on a minitype coal gas furnace and practice test showed that the algorithm is accurate and credible and realized the online monitoring for sudden spread combustion chamber raceway depth direction. At the same time, the useful information is provided for further studying combustion working state for the sudden spread combustion chamber.

7 Failure analysis of upsetbending equipment for a heavy crankshaft with continuous grain flow

XU Wujiao , WANG Kaiqing , ZHOU Jie , HU Fengtao

2009, 32(4):396-401. DOI: 10.11835/j.issn.1000-582X.2009.04.007

[Abstract](2028) [HTML](0) [PDF 4.10 M](1408)

Abstract:
A failure investigation is conducted on the upsetbending equipment of a heavy crankshaft with continuous grain flow which is broken in the first use after the crankshaft flange is modified to deform in the die cavity. The forging process of the heavy crankshaft is simulated using the DEFORM3D software, through which the forming load and die filling are calculated. Using the IDears software, the structural strength calculation for the upsetbending equipment is performed. The stress field and displacement in the equipment are obtained. The failure analysis of the die base is accomplished. The analysis results show that the practical crack location and orientation in the die base are consistent with those in the structural strength calculation.

8 Contact analysis of a newstyle planetary reducer with a double crank and internal gear board

ZHU Caichao , LUO Zhaoxia , NING Jie , LIU Weihui

2009, 32(4):402-407. DOI: 10.11835/j.issn.1000-582X.2009.04.008

[Abstract](2399) [HTML](0) [PDF 1.64 M](2216)

Abstract:
To address the problems of low carrying capacity and short life of bearings in current ring reducers, a new type of ring reducer is proposed which consists of a twostepped transmission. One is a planetary transmission, and the other is an Ntype planetary transmission with a low tooth number difference. Based on the analysis of structural features, the transmission principle, and a transmission load situation, a contact finite element model of the new type of ring reducer is set up, and the stress value and the actual pairs of meshing teeth are derived by calculation. Based on gear modification research theory, the second stage transmission gear pairs of the new reducer are modified on its teeth profiles. Results demonstrate that the load capacity of transmission gear pairs have been enhanced greatly.

9 Dynamic analysis and optimization of gear trains in a megawatt level wind turbine

QIN Datong , GU Xiguo , WANG Jianhong , LIU Jianguo

2009, 32(4):408-414. DOI: 10.11835/j.issn.1000-582X.2009.04.009

[Abstract](9168) [HTML](0) [PDF 1.13 M](8680)

Abstract:
Through coupling vibration analysis of the transmission system of a 1.5 MW wind turbine gearbox, a torsional vibration model of a gear drive system in wind turbines is established. The fourthorder RungeKutta integration method is applied to calculate the dynamic response of a gear system caused by wind loads, timevarying meshing stiffness, and system damping. The harmonic balance method is used to find the analytic solution. Based on the solution, a mathematical model for optimum gear system design is established. The model aims at minimizing the vibration acceleration of the planet gear and the total mass of the gear transmission system. The optimization toolbox in MATLAB program is adopted to obtain the optimal solution. A calculated example shows that the primary natural frequency of the gear system has been raised, the dynamic properties of the gear train have been improved remarkably, and the total mass of the gear train has been decreased.

10 The cooling structure of NiMH batteries in hybridelectric vehicles

YANG Yalian , ZHANG Xin , LI Longjian , QIN Datong , HU Minghui

2009, 32(4):415-419. DOI: 10.11835/j.issn.1000-582X.2009.04.010

[Abstract](2359) [HTML](0) [PDF 2.57 M](1644)

Abstract:
Focusing on NiMH batteries used in hybridelectric vehicles (HEV), a simulation analysis of the flow and temperature fields of the cooling structure in existing batteries is carried out using computational fluid dynamics software. The results show that the temperature uniformity is poor. The uniformity of the flow and the temperature fields is improved by adjusting the baffle and battery positions, changing the tilt angle and the distance between the batteries, inserting wind plates and a coating insulation layer. The coating insulation layer achieves the best effect. Further simulation shows that the coating insulation layer method has the best effects. The results provide the design basis for thermal management program of NiMH batteries in HEV.

11 Design and analysis of structural parameters for capillary oil film bearing

JIANG Guiyun , WANG Yongqin , YAN Xinchun , WANG Qing

2009, 32(4):420-424. DOI: 10.11835/j.issn.1000-582X.2009.04.011

[Abstract](2621) [HTML](0) [PDF 1.15 M](2155)

Abstract:
Structural parameters, such as the structure of recesses, the number of recesses, and throttle parameters, play decisive roles in determining the carrying capacity and rigidity of oil film bearings. These parameters are analyzed, and a state design is presented for a hydrostatic cavity and pat bearing, a hybrid bearing with an eccentric oil wedge, and ladder recesses. The mutual relationships between oil film bearing structural parameters and carrying capacity are calculated by combining numerical methods using MATLAB software programming. The results show that hybrid bearings with ladder recesses have superior carrying capacity compared to bearings with other structural forms.

12 Optimal decision of multiprocess routes in make to order discrete manufacturing enterprises

CHEN Xiaohui , JIA Nianlong , DUAN Ying , DING Xuan

2009, 32(4):425-429. DOI: 10.11835/j.issn.1000-582X.2009.04.012

[Abstract](1889) [HTML](0) [PDF 1.04 M](382)

Abstract:
To ensure more efficient planning and scheduling in discrete manufacturing enterprises, a planning and scheduling framework is studied in light of actual capacity states. An evaluation index system having synthetic consideration of capacity states, cost and time is built. A multiprocess route decision in a dynamic capacity condition is studied in detail. Taking gear shaft manufacturing as an application example, elimination et choix traduisant is realité (ELECTRE Ⅲ) is adopted to select the optimal process route. The same sorting results are attained using a descending and ascending distillation method.

13 Simulation and analysis of allterrain vehicle ride comfort

XU Zhongming , CUI Jinyu , ZHANG Zhifei , MU Xiaojing

2009, 32(4):430-433. DOI: 10.11835/j.issn.1000-582X.2009.04.013

[Abstract](1768) [HTML](0) [PDF 1.16 M](460)

Abstract:
A multirigidbody dynamic model of an allterrain vehicle (ATV) is established in MSC.ADAMS. The model takes into consideration the body, suspension, frame and the steering system. According to the method of superposition of harmonic wave, a Grade B road file is created in ADAMS for the riding comfort test. The engine excitation is analyzed. The infliction for engine excitation to ADAMS is achieved. The ATV ride comfort simulation is carried out with the excitation of the engine, and the seat vibration is evaluated using an evaluation method programmed via MATLAB. It has laid a good foundation for further analysis.

14 Stability analysis method for perilous rock by fracture mechanics

CHEN Hongkai  , XIAN Xuefu , TANG Hongmei

2009, 32(4):434-437. DOI: 10.11835/j.issn.1000-582X.2009.04.014

[Abstract](1657) [HTML](0) [PDF 1.06 M](566)

Abstract:
Perilous rock is a type of geological disaster in mountainous areas. Research concerning perilous rock ruptures focuses on the expanding of control fissures in perilous rock under load action. Taking the control fissure in perilous rock as one crevice in a sample, a method employing fracture mechanics is established to calculate the union fracture strength factor along the rupture orientation at the terminus of a control fissure in perilous rock. The union fracture strength factor is a function of both the firstand secondtype fracture strength factors. We define the ratio between the fracture tendency of rock and the union fracture strength factor as the stability coefficient of perilous rock. Further, it simplifies the rupture mechanism of sliding, falling, and toppling perilous rock as pressureshear and tensionshear ruptures. We establish methods for calculating the firstand secondtype fracture strength factors. The applications show that the stability status identified by the method is more reasonable and sensitive.

15 Analysis of a steel tubular column filled with equidistant fiber reinforced polymerringstiffening concrete

YANG Youf , CHEN Yuan

2009, 32(4):438-442. DOI: 10.11835/j.issn.1000-582X.2009.04.015

[Abstract](1838) [HTML](0) [PDF 1.25 M](550)

Abstract:
Based on theory of cylinders subjected to uniform internal pressure, the mechanical performance of a steel tubular column filled with equidistant fiber reinforced polymer (FRP)ringstiffening concrete is investigated. The solutions for the stress and displacement are regarded as the superposition of elementary and improved solutions. The elementary solutions are found by using twodimensional elastic theory. The improved solutions are found by using the Love displacement function method. Considering the conditions of the displacement continuum of the FRP ring and the steel tube exterior, a more accurate solution for an equidistantly FRPringstiffened cylinder subjected to a uniform internal pressure is obtained. Several numerical calculations are also carried out. The results indicate the solutions possess good convergence.

16 A simulation experiment of the thermal response of steel structures in fires

LIU Chao , CHEN Jie , ZHANG Hualing , LI Ming

2009, 32(4):443-446. DOI: 10.11835/j.issn.1000-582X.2009.04.016

[Abstract](1730) [HTML](0) [PDF 1.85 M](498)

Abstract:
A standard indoor temperature rising curve is simulated by using a 10 kW electrical furnace. DN20 seamless steel tubes are horizontally placed on top of the electrical furnace. The distances between the bottom of the steel tubes and the mouth of electrical furnace are 0.5 cm, 5 cm, 10 cm and 15 cm, respectively. Experiments regarding the thermal response of an unshielded steel tube, a steel tube with an external fire retardant coating, and a concretefilled steel tube are carried out. When the temperature of lowest point of the bottom of the unshielded steel tube is 400 ℃, the temperature of corresponding points of the steel tube with an external fire retardant coating and the concretefilled steel tube are 215 ℃ and 200 ℃, respectively. It is concluded that the steel tube fireresistance limit exceeds 2 hours when the exterior of a steel tube is coated with fire retardant or if steel tubes are filled with concrete because these modifications improve their thermal insulation and decalescence.

17 Hybrid fieldnetwork simulation of temperature in a building fire

WANG Houhua , XIONG Jie , HU Yang

2009, 32(4):447-452. DOI: 10.11835/j.issn.1000-582X.2009.04.017

[Abstract](1720) [HTML](0) [PDF 6.19 M](378)

Abstract:
A connecting platform between the field model and network model has been constructed, based on a multifunctional building model. The field model is used to simulate the fire smoke in certain special compartments (the fire room and specific largespace rooms), while the network model is used to simulate the uniform compartments. When combining the simulation results of the field model and network model as the interface boundary conditions for the each other, a hybrid field and network model is presented. The hybrid fieldnetwork model can provide more detailed physical information of the fire smoke properties under a specific fire scenario for the specially confined compartments. In addition, the hybrid model can predict the fire smoke flow properties in the building accurately.

18 An electromagnetic interference design of a high speed image acquisition system on DM642

GAO Chao , LI Jianzhong , GUO Yongcai

2009, 32(4):453-457. DOI: 10.11835/j.issn.1000-582X.2009.04.018

[Abstract](1742) [HTML](0) [PDF 2.67 M](457)

Abstract:
A novel design is presented to defend against electromagnetic interference (EMI) in a high speed data acquisition system. Problems that affect signal integrity (SI) in high speed image acquisition systems, such as reflection, crosstalk and groundbounce, are deeply analyzed in a manner consistent with transmission line theory. The results can theoretically inform EMI design of important networks, including system power, ground, clocks, high speed wires and decoupling capacitors. Experiments simulating print circuit board(PCB) reflection and EMI on high speed signal wires between DM642 and SDRAM are conducted. The power and ground should be placed separately in different layers. The clock lines passing through holes should be as few as possible. The signal lines should be as close to the same length as possible. The results show that amplitude of the signal overshoot is less than 0.7 V and the EMI amplitude is within the federal communications commission(FCC) standard.

19 Performance analysis and comparison of IEEE 802.11 distributed coordination function and improved schemes

SONG Jun , HUANG Jian , JIN Yanhua

2009, 32(4):458-462. DOI: 10.11835/j.issn.1000-582X.2009.04.019

[Abstract](1708) [HTML](0) [PDF 2.47 M](412)

Abstract:
To improve the media access control mechanism and enhance the performance of largescale wireless LANs, the distributed coordination function of IEEE802.11 standard and two typical improved schemes are studied extensively. Compared with the distributed coordination function, the fast collision resolution mechanism greatly enhances the throughput, but deteriorates the delay jitter and fairness of wireless LANs. The new selfadaptive distributed coordination function markedly improves the delay jitter and fairness performance, while enhancing the throughput of wireless LANs to a certain degree. Hence, with further improvement, the new selfadaptive distributed coordination function is more suitable for largescale wireless LANs for multimedia information transmission.

20 Synthetic aperture radar raw signal generation and image simulation of typical targets

XIA Weijie , ZHOU Jianjiang

2009, 32(4):463-467. DOI: 10.11835/j.issn.1000-582X.2009.04.020

[Abstract](2372) [HTML](0) [PDF 1.60 M](408)

Abstract:
Synthetic aperture radar (SAR) raw signal generation and SAR image simulation of typical targets are very significant for the validation of SAR imaging algorithms, the interpretation of SAR images, and automatic target recognition of SAR images. Based on analysis of the existing SAR raw signal generation and SAR image simulation methods, a new method for SAR raw signal generation and SAR image simulation is proposed. This method combined the curved surface pixel method (CSPM) and the twodimensional FFT (2DFFT) based SAR raw signal generation model. CSPM is used to calculate the target reflectivity, while the 2DFFT method is employed to obtain the raw signal. The simulations are carried out, and the effectiveness of this method is validated by the results of simulating some typical targets.

21 Coupling design for highpower millimeter wave in the overmoded waveguides mode

CHENG Liwei  , NIU Xinjian

2009, 32(4):468-471. DOI: 10.11835/j.issn.1000-582X.2009.04.021

[Abstract](2280) [HTML](0) [PDF 1014.96 K](545)

Abstract:
Based on the mode coupling theory, the design of the geometric configuration for an TM01TE11,TE01TM11,TE0nTE01 and TE01TE11 overmoded circular waveguide mode converter with different phase rematch and structure is given to obtain more acceptable geometry parameters. The regulation of the radius of the circular waveguides, the curvature and frequency of bent circular waveguides, and the bandwidth also are obtained. With the results, a compact, efficient and wideband circular waveguide mode converter can be designed.

22 An improved session initiation protocol signaling compression algorithm based on lempel ziv storer szymanski and Huffman

YING Qian , YING Jun

2009, 32(4):472-475. DOI: 10.11835/j.issn.1000-582X.2009.04.022

[Abstract](2160) [HTML](0) [PDF 1.93 M](1641)

Abstract:
Session initiation protocol(SIP) has been chosen as the call/session control protocol in IP multimedia subsystem(IMS). However, large SIP messages create a bottleneck for SIP application in IP multimedia subsystem(IMS) in wireless applications. Based on the SigComp, and by comparing various compression algorithms, lempel ziv storer szymanski(LZSS) is selected as the basic algorithm to compress SIP in accordance with the characteristics of messages in SIP protocol. To further improve the compression ratio, a new algorithm is proposed based on LZSS and Huffman. The performance of the compression algorithm is analyzed via simulation.

23 The optimal energy efficiency of wireless networks nodes based on solar cells

TAN Chunlu , LIU Yong , LI Xiuzhen , ZHONG Yuanchang

2009, 32(4):476-480. DOI: 10.11835/j.issn.1000-582X.2009.04.023

[Abstract](1658) [HTML](0) [PDF 1.02 M](1698)

Abstract:
To improve the energy efficiency of solar cells in wireless sensor networks nodes, the energy relationship between solar cells and the wireless sensor networks nodes is studied. An adaptive algorithm is adopted to ensure the wireless sensor networks work normally at different sunlight intensities. An energy model is designed that reveals the energy relationship between the output power of the solar cells and the power of nodes working normally at a standard sunlight intensity. The experimental results show that the model represents the adaptive energy relationship between the solar cells and the nodes, ensures that the nodes work stably in a long term, and extends the lifecycle of the sensor networks as long as possible. The model has important guiding significance for wireless sensor networks designation.

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