Table of Content

30 October 2015, Volume 21 Issue 5

Previous Issue    Next Issue

Metallurgical Materials

Measurement of Jones-Mueller matrix for cascaded optical system

LEI Jun-ping, WANG Chun-hua, YU Qing-yang, DU Yan-xia, ZHANG Bin

2015, 21(5):  525-535.  doi:10.3969/j.issn.1007-2861.2014.05.014

Asbtract ( 1028 )   PDF (11732KB) ( 446 )  

References | Related Articles | Metrics

Based on system estimation, a method for measuring Jones-Mueller matrices of optical fiber systems using optical fiber wave-plates is proposed, and studied theoretically and experimentally. The measurement system uses optical fiber wave-plates that match the fiber system naturally. The method is feasible but with drawbacks of environmental sensitivity. To overcome the problem, a method for calibrating the retardance of waveplates is proposed and realized based on the property of similar matrices. Adjustment of rotation of optical fiber wave-plate is also achieved using system optimization. Both retardance calibration and rotation adjustment are verified experimentally. Significant improvement in the reduction of system error has been shown. The spectra of Mueller matrices of two segments of fiber in tandem are measured in the region of 1 520~1 620 nm using the proposed method.

Inter-carrier interference self-cancellation for MIMO-OFDMsystems in high-speed train environment

WANG Jun-hua, JIAO Wu-chen, FANG Yong

2015, 21(5):  536-546.  doi:10.3969/j.issn.1007-2861.2014.05.016

Asbtract ( 1078 )   PDF (6987KB) ( 367 )  

References | Related Articles | Metrics

Wireless communication channels for high-speed train (HST) systems are nonstationary and time-varying. A joint algorithm of inter-carrier interference (ICI) selfcancellation and zero forcing (ZF) equalization is proposed for multiple-input multipleoutput orthogonal frequency division multiplexing (MIMO-OFDM) systems used in the HST environment. At the receiver, cyclic prefix (CP) and linear weight average, and combing the subsequences extracted from each OFDM symbol are used to achieve ICI selfcancellation. The new OFDM symbol with ICI reduced is equalized by ZF equalization. The transmitted signal is then obtained by hard decision. Simulation results show that ICI can be effectively reduced by using CP, and the carrier-to-interference ratio (CIR) is raised. Besides, the proposed algorithm outperforms the ZF equalization method in terms of bit error rate (BER), and therefore ensures better quality of communications.

9-axis MEMS-IMU real-time data fusion algorithm for attitude estimation

ZHANG Jin-yi1,2,3, XU De-zheng2, LI Ruo-han1,CHEN Xing-xiu1, XU Qin-le2

2015, 21(5):  547-559.  doi:10.3969/j.issn.1007-2861.2014.01.037

Asbtract ( 2359 )   PDF (13294KB) ( 1268 )  

References | Related Articles | Metrics

To meet urgent application demands in indoor location and motion tracking, studies on low-cost high-resolution and real-time micro-electro-mechanical system-inertial measurement unit (MEMS-IMU) have attracted much attention. This paper presents a quaternion-based data fusion algorithm for real-time attitude estimation, including factored quaternion algorithm (FQA) for static attitude estimation, and Kalman filtering fordata fusion. A singularity avoidance method, axis-exchanged compensation, is proposed to modify the FQA, allowing the algorithm to track at all attitudes. An R-adapted module is designed to adjust the Kalman gain, which effectively restrains noise due to dynamic nonlinear acceleration, and improves attitude estimation accuracy. Experimental results show that the R-adapted Kalman filter can accurately estimate attitudes in real-time. Additionally, FQA with an axis-exchanged method has good performance in estimating attitudes of singularity points, and the computational efficiency is higher than a previous method by 50%.

Allocation scheme of short training sequence based on OFDM-PON

CHEN Xi, XU Chao-xing, JIANG Yuan, LI Ying-chun

2015, 21(5):  560-569.  doi:10.3969/j.issn.1007-2861.2014.03.014

Asbtract ( 1007 )   PDF (15413KB) ( 1834 )  

References | Related Articles | Metrics

A short training sequences for orthogonal frequency division multiplexingpassive optical network (OFDM-PON) symbol synchronization is proposed. By adjusting the subcarrier allocation scheme of short training sequence in a wireless local area networks (WLAN), the mean of short training sequence signal in time domain is made from non-zero to zero, overcoming interference of receiving data demodulation caused by the wrong trail of the non-zero mean short training sequence in the time-domain. Simulation and experiments on data demodulation show that the improved method can effectively reduce training sequence interference errors caused by tailing.

Design and implementation of FPGA 10 Gbit/s reliable interconnect communication based on IP protocol

SONG Yu-fei, ZHANG Jun-jie, WANG Kai, LI Jia-qi, XUE Zi-wei, ZHENG Yue

2015, 21(5):  570-578.  doi:10.3969/j.issn.1007-2861.2014.05.015

Asbtract ( 895 )   PDF (11057KB) ( 347 )  

References | Related Articles | Metrics

In recent years, cloud computing and big data processing have been rapidly developed. Since field programmable gate array (FPGA) has the unique parallel processing ability, it is widely used in big data processing. As the performance of communication network directly affects the performance of big data processing, this paper presents a high speed and reliable communication system based on IP protocol for FPGA communications. The system uses a three-pointer ring buffer pool and a method of parallel number management to achieve data transmission at a line-speed of 10 Gbit/s. By implementing hardware timeout retransmission mechanism, the system can guarantee reliable communications. A self-defined reliable IP protocol is used in the system, which has a small overhead and a good system expansion. Tests on the FPGA hardware platform show that the real data transfer speed can reach 9.33 Gbit/s.

Modes and fields for a chiral negative refraction parallel-plate waveguide under PMC boundary

MA Quan-wen, XIAO Zhong-yin, XU Xiao-xue, XU Wen-jie, MA Xiao-long, LIU De-jun, WANG Zi-hua

2015, 21(5):  579-587.  doi:10.3969/j.issn.1007-2861.2014.03.013

Asbtract ( 1170 )   PDF (5813KB) ( 386 )  

References | Related Articles | Metrics

The mode characteristics and magnetic distributions of a chiral negative refraction parallel-plate waveguide under perfect magnetic conductor (PMC) boundary are studied theoretically. With boundary conditions of PMC, dispersion relations and electromagnetic fields are obtained. Using the dispersion curves, if the chirality parameter κ >1, curves become concave-down in some regions and the refractive index of left circularly polarized (LCP) wave is negative. It imply that chiral medium can realize negative refraction. The cutoff frequency is no longer the conventionally defined frequency when propagation constant is zero. According to the relations between propagation constant β and wavenumbers k₊ and k₋, the dispersion curves are divided into three regions. Amplitudes of magnetic field components on the first-order even mode and first-order odd mode are plotted respectively. Chatacteristics of the magnetic field components are discussed and compared with the conventional chiral slab waveguide. It is shown that H_y and H_z are zero at x/d = ±0.5. It indicates that they satisfy the PMC boundary conditions and,due to the existence of magnetic current, H_x is not zero at the interface.

Inverse kinematics analysis of modular manipulator by separating attitude from position

LEI Jing-tao, DAI Wen-jie

2015, 21(5):  588-597.  doi:10.3969/j.issn.1007-2861.2014.02.015

Asbtract ( 1141 )   PDF (5581KB) ( 675 )  

References | Related Articles | Metrics

The kinematics for a 7-DOF (degrees of freedom) redundant manipulator is analyzed. The Denavit-Hartenberg (D-H) method is used to analyze forward kinematics. Position and attitude of the end-effector with respect to the base are obtained. Attitude is separated from position in analyzing inverse kinematics. For the position inverse kinematics, angular-displacement of the former four joints is obtained under a constraint condition. For the attitude inverse kinematics, the Euler angles are used to describe attitude of the end-effector with respect to the base. This way, the calculation is reduced. For the modular 7-DOF manipulator produced by SCHUNK, kinematics is analyzed and verified by virtual prototyping simulation.

Direct torque control of permanent magnet synchronous motor based on space vector modulation control

YANG Ying, HAN Bing, CHEN Xin, TU Xiao-wei

2015, 21(5):  598-605.  doi:10.3969/j.issn.1007-2861.2014.04.004

Asbtract ( 1293 )   PDF (2083KB) ( 786 )  

References | Related Articles | Metrics

To obtain the reference voltage vector is a key to the direct torque control (DTC) of permanent magnet synchronous motor (PMSM) based on the space vector modulation (SVM). From the control effect of the voltage vector on electromagnetic torque, the analysis shows that the limited number of voltage vectors is a primary cause of large ripple in the torque and flux of a DTC system. A robust DTC method of PMSM based on SVM is proposed. Amplitude and phase angle of the reference voltage vector is calculated according to the flux phase position, errors in the torque and flux, which is insensitive to motor parameters. Simulation and experimental results show that the improved DTC method based on SVM with a simple structure has strong robustness and can greatly improve the DTC performance.

Deformation analysis of model test of sand foundation reinforced with high-strength geocell

ZHENG Chao-yi1, ZHANG Meng-xi1, JIANG Sheng-wei2, HAN Xiao1, SUN Zhou1

2015, 21(5):  606-616.  doi:10.3969/j.issn.1007-2861.2014.02.021

Asbtract ( 1318 )   PDF (7298KB) ( 305 )  

References | Related Articles | Metrics

High-strength geocell’s strength is about 10 times higher than ordinary geocell with the new screw joint of U shape. The foundation placed with geocell is called a structural layer. By analyzing the pressure-settlement (p-s) curves based on a series of model tests of pure sand foundation and geocell reinforcement foundation with different weld spacing, the test shows that geocell reinforcement can increase bearing capacity and reduce the settlement. Within a certain range, the effect of reinforcement increases with the decrease of the weld spacing. The theory of Winkler model is used in the settlement calculation of sand foundation reinforced with high-strength geocell to get a solution of finite-length beam on elastic foundation, accurately confirming parameters with the measured data from the experiment. The method of deformation analysis of structure layer reinforced with high-strength geocell and the relevant parameters of high-strength geocell are summarized by comparison of experimental and computational results.

Dynamical response of nearly saturated soil with deeply buried circular tunnel under axisymmetrical blasting load

WU Chuan-xia, ZHANG Min, YANG Xiao

2015, 21(5):  617-630.  doi:10.3969/j.issn.1007-2861.2014.02.005

Asbtract ( 1136 )   PDF (16754KB) ( 274 )  

References | Related Articles | Metrics

Considering the non-complete connection between nearly saturated soil and elastic lining of a tunnel, the dynamical responses of nearly saturated elastic soil with a deeply buried circle tunnel subject to an axisymmetrical blasting load are investigated based on the Biot model and elasticity. Analytical solutions of dynamical responses of nearly saturated soil and elastic lining coupled system in the Laplace transform space are derived with the potential function and Laplace transform. The time-history responses of the coupled system are obtained with a numerical Crump method of the inverse Laplace transform. The dynamical responses of nearly saturated soil with different tunnel lining models are analyzed. It is shown that the soil responses of nearly saturated soil and a shell lining system are minimal, while the soil responses of nearly saturated soil without lining are maximal. Influence of the degree of saturation on displacement and stress of the soil is weak, but has evident influence on pore water pressure. Furthermore, the magnitudes of radial displacement and circumferential stress increase as stiffness of the interface increases.

Initial state determination and static analysis of composite cable and steel/aluminum structures

ZHANG Li

2015, 21(5):  631-639.  doi:10.3969/j.issn.1007-2861.2014.05.009

Asbtract ( 1019 )   PDF (1039KB) ( 330 )  

References | Related Articles | Metrics

Composite cable and steel/aluminum structure is a new system. It is in a selfstress and stable self-equilibrated state, comprising a continuous set of tension members
(cables) and a discontinuous set of compression components (steel pipes or alloy tubes). Starting from an initial specified geometry and topology, the initial self-stress is determined using a dynamic relaxation method. The behavior of the structure is analyzed for safely resisting the self-weight and applied static load using the Newton-Raphson method. To understand its mechanical property, steel pipes and alloy tubes are used as compression members respectively in the two kinds of composite structures. Application of the process is shown with a numerical example. It is concluded that that improvement in engineering application of the composite cable and steel/aluminum structure has been achieved.

Layout of monitoring points in water supply network based on information maximization criterion

CHEN Ling-li, ZHUANG Wei-tan, HE Xin

2015, 21(5):  640-647.  doi:10.3969/j.issn.1007-2861.2014.04.009

Asbtract ( 1150 )   PDF (847KB) ( 383 )  

References | Related Articles | Metrics

The objective of system monitoring is mainly for diagnoses or forecasting. Monitoring points should be highly sensitive, and their outputs should have low correlation to avoid information redundant, therefore the obtained information is more useful in reliable diagnoses or forecasts. To maximize usefulness of the monitoring information, an effective independence method, a maximization criterion of Fisher information matrix, and correlation coefficients are used to determine the monitoring points based on the sensitivity analysis of water supply network. Finally, a water supply network is analyzed, and schemes of the three methods compared with that of the traditional cluster analysis method. It is shown that the monitoring points and their corresponding monitoring areas can be determined using the method of monitoring point locating based on correlation coefficients. The method is more simple, stable and efficient, so it is better than other methods.

Effect of B content on structure and mechanical properties of (Fe, Ni)₃V alloy

HOU Xi-bei, CHEN Ye-xin

2015, 21(5):  648-656.  doi:10.3969/j.issn.1007-2861.2014.03.002

Asbtract ( 1138 )   PDF (5338KB) ( 354 )  

References | Related Articles | Metrics

The mechanical properties and fracture mode of disordered and ordered (Fe, Ni)₃V alloys with different boron contents in vacuum at the ambient temperature are studied. The results show that the grain size decreases continuously, and tensile strength and elongation increase with the increase of the boron content in the disordered and ordered (Fe, Ni)₃V alloys. The effect of boron content on the mechanical properties of the ordered (Fe, Ni)₃V alloy is significantly larger than that of the disordered (Fe, Ni)₃V alloy. It is deduced by the fracture surface morphology varying with the boron content in the ordered (Fe, Ni)₃V alloy that the change of the fracture mode is attributed to the segregation of boron on the grain boundary, thereby increasing strength of the grain boundary. Increases of the mechanical properties of the disordered (Fe, Ni)₃V alloy come from the effect of the grain size decrease. The increases of the mechanical properties of the ordered (Fe, Ni)₃V alloy are attributed to the joint effect of ordered strengthening, decreasing the grain size and improving the property of the grain boundary by boron atom.

Coplanar-grid electrode design of HgI₂ detector with finite element simulation and optimization

LU Shu-yi, LI Dong-mei, YANG Wei-guang, HUANG Lu, JIN Jing, WANG Chen, CHEN Yang, SHI Wei-min

2015, 21(5):  657-662.  doi:10.3969/j.issn.1007-2861.2014.05.007

Asbtract ( 1214 )   PDF (7549KB) ( 250 )  

References | Related Articles | Metrics

Polycrystalline mercuric iodide films are developed as new detectors in room temperature X-ray imaging. In this paper, 8 different electrode patterns are designed by varying the widths of grid and gap. Finite element analysis is used to simulate the potential distribution of the coplanar-grid detectors. The electrode design of pattern E, with width of grid 150 μm and width of gap 500 μm, is the best. The influence of edge effects resulting from the unsymmetrical electrodes on the potential distribution is discussed. The geometry of electrodes for coplanar-grid detectors is optimized by widening the second grids near edges as shown in pattern N.

Transformation and retained austenite of two kinds of bainite plastic mold steel

LI Na, MIN Yong-an, ZHANG Zheng, WU Xiao-chun

2015, 21(5):  663-670.  doi:10.3969/j.issn.1007-2861.2014.01.033

Asbtract ( 951 )   PDF (5899KB) ( 335 )  

References | Related Articles | Metrics

FT600 and FT600mod steels are two similar non-quenched plastic mold steels with difference in the content of Si and Mn. Both FT600 and FT600mod were cooled by
continuous and isothermal treatments after austenitizing respectively, and then separately tempered at 350, 580, and 700 °C. Evolution of microstructures and retained austenite of the two bainitic steels after the heat treatments are studied based on the microstructure characterization, content measurement, and Rockwell hardness and dilatometric analysis experiments. It is found that the content of the retained austenite of continuous cooling sample of FT600mod, different from FT600 by decreasing Si and increasing Mn, is decreasing dramatically. The changed amounts of retained austenite of FT600 sample vary after different tempering treatments. FT600mod steels are more stable and more suitable for the non-quenched treatment.