Table of Content

26 April 2014, Volume 20 Issue 2

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Speical Paper

A Model Structured in Classes for the Study of Student Population Evolution

PEREIRA Edgar1, ROSA Cecilia2, SILVA Jacques3

2014, 20(2):  127-137.  doi:10.3969/j.issn.1007-2861.2014.01.020

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This paper presents an application of a metapopulation model structured in classes for the study of population evolution of a network of schools. The global dynamics are considered in two parts, the local, where the evolution for each grade in a cycle is ac-counted, and the metapopulation or the movement of students between schools. Simulation of the model is presented.

A Pair of Mixed Generalized Sylvester Matrix Equations

HE Zhuo-heng, WANG Qing-wen

2014, 20(2):  138-156.  doi:10.3969/j.issn.1007-2861.2014.01.021

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In this paper, some necessary and sufficient solvability conditions for the system of mixed generalized Sylvester matrix equations A₁X − Y B₁ = C1, A₂Y − ZB₂ = C₂ are derived, and an expression of the general solution to this system is given when it is solvable. Admissible ranks of the solution, and admissible ranks and inertias of the Hermitian part of the solution are investigated, respectively. As an application of the above system, solvability conditions and the general Hermitian solution to the generalized Sylvester matrix equation are obtained. Moreover, we provide an algorithm and an example to illustrate our results.

Communication and Information Engineering

Personalized Modeling of Head-Related Transfer Function Based on RBF Neural Network

HUANG Qing-hua, LI Lin, LAI Shi-cun

2014, 20(2):  157-164.  doi:10.3969/j.issn.1007-2861.2013.07.019

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A nonlinear personalized model is established to predict individual head-related transfer function (HRTF). Principal component analysis (PCA) is applied to obtain individual weights as the outputs of the model. Some important anthropometric parameters are selected according to the Laplacian score and correlation analyses between all measured parameters and the individual weights. They act as the inputs to the model. Constructing a radial basis function (RBF) neural network to learn the nonlinear model, the individual HRTF can be predicted according to the measured anthropometric parameters. Simulation results show that the proposed method outperforms the partial least squares regression (PLSR) method in predicting individual HRTF.

Multi-sensor Data Fusion Algorithm for High Accuracy Arc Fault Detection

XU Qin-le1, ZHANG Jin-yi,1,2,3, XU De-zheng1, LI Ruo-han2, ZHANG Jing-jing2

2014, 20(2):  165-173.  doi:10.3969/j.issn.1007-2861.2013.07.018

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Since physical characteristics of arc fault are complex and there are loads with waveforms similar to arc fault in circuits, misjudgment of traditional arc fault detection methods is high. To improve the arc fault detection accuracy, a multi-sensor data fusion algorithm that includes an adaptive weighted fusion algorithm and a neural network fusion algorithm is proposed. Date is acquired with a temperature sensor, an acoustic sensor and a light sensor. The adaptive weighted fusion algorithm can overcome uncertain of single sensor, extract the arc fault characteristics of homogeneous sensors, and provide accurate test sample date for neural network fusion, making the probability of identifying arc fault more accurately by automatically adjusting the weights for all kinds of heterogeneous sensors. Experimental results show that the algorithm can effectively extract the arc fault characteristics and improve identification accuracy up to 98%, meeting the high accuracy arc fault detection requirement.

Tri-band Bandpass Filter Using Short and Open Stub-Loaded Resonator

LI Hao, XIAO Zhong-yin, CHU Jun-jun, LIU Yang, XU Xiao-xue, MA Quan-wen

2014, 20(2):  174-179.  doi:10.3969/j.issn.1007-2861.2013.07.004

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A tri-band bandpass filter has been designed using open-loop resonator with open and short stubs. The filter can control each center frequency independently. An odd-even mode analysis is performed on the resonator. The center frequencies of the first and third passbands are obtained with the even mode, and determined by the electrical length and impedance ratio of the stubs. The center frequency of the second passband is obtained with the odd mode and determined by the electrical length and impedance of the open-loop. The filter has triple passband center frequencies of 1.57 GHz for GPS, 2.4 GHz for WLAN, and 3.5GHz for WIMAX, with 3dB fractional bandwidths of 2.5%, 4.7%, and 2.0% , respectively. Measurement results are in general agreement with EM simulation results.

Computer Engineering and Science

MPI Programming Based on Ternary Optical Computer in Supercomputer

ZHANG Qian1,2, JIN Yi1,2, SONG Kai1,2,3, GAO Huan1,2

2014, 20(2):  180-189.  doi:10.3969/j.issn.1007-2861.2013.07.001

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An MPI method is proposed to make the ternary optical computer (TOC) node cooperate with other general compute nodes in a cluster supercomputer in an MPI program. The TOC nodes work as servers, running a process to wait for connections. Any MPI process running on CPU works as a client side, using a series of expand instructions with the prefix of SHDX to contact the TOC node. After the TOC node gets contact with the MPI process on the CPU nodes, MPI process sends an operation request and data to the TOC in a connection. Then, TOC exerts the advantages of its reconfigurable processor and high data-bit-width to process the data and sends the results back to the MPI process. This method realizes using TOC on the instruction level. At present, there can be at most 10 TOC nodes in a supercomputer system, and each TOC node opens 8 ports. Future versions may break these restrictions. Experimental results show feasibility and practicality of the method.

Document Clustering Method Based on Association Link Network

HE Xiang, LUO Xiang-feng

2014, 20(2):  190-198.  doi:10.3969/j.issn.1007-2861.2013.07.003

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This paper proposes a document clustering method with adaptive divisions based on association link network. Instead of explicitly offering the number of cluster centers in the traditional document clustering algorithms, categories were acquired auto- matically by detecting the community structure in association link network. Simultane- ously, with the consideration of the high-dimension and sparse word vectors that result in low similarities between the documents, the relationships were mapped between words in association link network to the relationships between the documents. Through the experimental comparisons with other clustering methods, it was found that the proposed clustering method not only obtains a high aggregation accuracy, but also are good at adap- tively discovering the number of cluster centers and distinguishing categories of topics.

Mathematics.Physics and Chemistry

Effect of Multiple Boundary Constraints on Vibration Characteristics of Triple-Walled Carbon Nanotubes

WU Bing-jie, PENG Xiang-wu, LIU Liang, WANG Qing-zhan, GUO Xing-ming

2014, 20(2):  199-206.  doi:10.3969/j.issn.1007-2861.2013.07.012

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Vibration characteristics of triple-walled carbon nanotubes (TWCNTs) with multiple boundary constraints are studied. TWCNTs are modeled as a coupling Euler beam system in which the inner, middle and outer tubes are simulated as 3 single beam, respec- tively. They are coupled through van der Waals interaction. Besides, different boundary conditions are imposed on the three beams. The effect of FFC multiple boundary con- straints on the vibration characteristics of TWCNTs are analyzed. The results show that FFC multiple boundary constraints can reduce resonant frequencies of TWCNTS, espe- cially on the lower modes. Meanwhile, it is also found that this effect will be weakened with the increase of the length of TWCNTs.

Optimal Design of Centrifugal Pumps with Gap Drainage Blades

SUN Tao, CHEN Hong-xun, ZHU Bing, ZHANG Wei-yong

2014, 20(2):  207-213.  doi:10.3969/j.issn.1007-2861.2013.07.008

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The impact of gap drainage blades’ position on the hydraulic performance of a low specific speed centrifugal pump is studied. A fully automatic integrated optimization platform is used, which includes blades parametric design, meshing, computational fluid dynamics (CFD) calculations and post-processing. The hydraulic efficiency maximization of a centrifugal pump impeller is taken as the objective function. Design of experiments (DOE) and sequential quadratic programming (SQP) are used for optimal design. The comparison between the optimal impeller and the original impeller shows that the jam effect has been reduced, and the head improved. Specifically, efficiency of the optimal impeller is higher than the original after the condition 0.6Q, and the maximum efficiency point is improved by 2%. The results indicate feasibility of the design method.

Spectral Characteristics of the Liquid Falling Film Along the Inclined Sinusoidal Wall at Low Reynolds Number

HUANG Xiao-long, HU Guo-hui

2014, 20(2):  214-220.  doi:10.3969/j.issn.1007-2861.2013.07.009

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Unsteady film flow along an inclined corrugated wall behaves a variety of complex features. By utilizing volume of fluid (VOF) method to capture the evolution of free surfaces, the liquid falling film along the inclined sinusoidal wall for the different applied frequencies of the periodic disturbance is simulated numerically to study the spatial evolution of the waves. Results obtained indicate that the evolution of the surface wave is dominated by the interaction of the traveling wave induced by the disturbance applied at the inlet and static wave determined by the wall structure. With the application of synchrosqueezing wavelet transforms, the spatial frequency spectrum of the surface wave is analyzed, and the influences of the wall structure on the wave numbers of traveling waves are studied, as well as the dynamical behavior of both traveling wave and static wave.

Optimization of Ligands in Nickel-Catalyzed Cross-Coupling of Alkyl Halides

XU Hai-liang1, ZHANG Yu-wei2, WANG Shu-lin1, LIANG Shuo1, TONG Wei-qi1

2014, 20(2):  221-227.  doi:10.3969/j.issn.1007-2861.2013.07.006

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Construction of C(sp³)—C(sp³) bonds through direct nickel-catalyzed reductive cross-coupling of two structurally similar alkyl halides remains a challenge in organic synthesis. In the previous studies, under catalytic Ni(cod)2 in the presence of stoichiometric amount of Zn as reductant, two different alkyl halides can efficiently undergo coupling to give desired alkyl-alkyl products. However, one of the reactants has to be largely excessive. In order to improve coupling efficiency, this reaction by using 1 mol of (4-CI)-H-Pybox and 2 mol of Ni(cod)₂ as model reactants was optimized. After screening a variety of tridentate and bidentate ligands, it was determined that the ligand remained optimal. However, bidentate ligand also gave moderate results in the presence of pyridine. This result may become important in future optimization.

Civil Engineering

Experimental Study on Electro-Osmosic Consolidation of Soft Clay under Preloading and Variable Voltage

LIU Fei-yu , ZHANG Le , WANG Jun , ZHANG Bin

2014, 20(2):  228-238.  doi:10.3969/j.issn.1007-2861.2013.07.005

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A series of tests were conducted to investigate the consolidation mechanism and effect of the combined application of electro-osmosis drainage and preloading. Test results for consolidation with variable voltage gradient, consolidation with variable loads and consolidation with constant preloading loads were presented and discussed. Current, soil flow, soil moisture content, displacement, soil conductivity, soil pH and other indicators were monitored during the tests. The effect of preloading loads and voltage gradient on electro-osmosis drainage was explored and the corresponding relationship between the preloading loads and the voltage gradient was established. The test results indicate that, compared to improved electro-osmosis voltage, increasing preloading loads can increase soil flow significantly. Preloading loads can increase soil flow at the cathode outfall. The effect of soil treatment with 40 kPa preloading loads is roughly equal to that of electro-osmotic consolidation with 0.5 V/cm voltage gradient. The effect of electro-osmotic consolidation with 1 V/cm voltage gradient is roughly equal to that of preloading with 50∼60 kPa loads.Compared to the effect of electro-osmosis drainage or preloading, the combined application of preloading and electro-osmosis drainage can significantly improve the effect of soil treatment.

Numerical Study on Statically Pressured Pile and Its Masking Effect of Driven Pile

QIN Shi-wei, MO Long, ZHOU Yan-kun

2014, 20(2):  239-249.  doi:10.3969/j.issn.1007-2861.2013.07.010

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This paper compares the analytical and numerical solutions of the cavity expansion theory based on calculations using the 3D finite difference software FLAC3D. By simulating pile-soil friction using the displacement penetration method, comparison of the result of applied nodal force is in good agreement with the literature. Based on the simulation method, calculation and analysis of the  static pressure single pile, double pile driving process, and impact on the displacement of the pile driving from driven pile, the following conclusions can be reached: The horizontal displacement on the surface is bigger. The
reason is constraintting the radial displacement when the pile body move downward at a constant speed which is in order to prevent the circular hole necking. After pile driving, the depth range of more than 1/8 pile length is the main deformation area, so the horizontal displacement is bigger. The upper soil subsidence is bigger than the lower region. The largest settlement appears below the surface by 1/8−1/4 of the pile length. Pile driving process makes the pile a bit tilt. Due to the impact of the pile driving reaming, the soil uplifts along the driven pile because of the pile barrier. This is the substance of the masking effect, achieving the purpose of reducing horizontal displacement by changing the distribution of soil displacement.

Soil-Water Characteristics of Huai-an Expensive Soil

WU Yi-gao, SUN De-an

2014, 20(2):  250-260.  doi:10.3969/j.issn.1007-2861.2013.07.007

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To investigate soil-water characteristic curve (SWCC) of Huai-an expanded soil, three different suction control or measurement methods are used. These are the pressure plate method for low suction, the filter paper method, and the vapor equilibrium technique for high suction. SWCC shows obvious hysteresis features during drying and wetting circle in the low suction range. When the suction is greater than 100 MPa, the hysteresis effect of SWCC disappears, and the drying and wetting curves are almost the same. Test data of SWCC, obtained using the filter paper method, are between the main drying and wetting
SWCCs. The tendency of SWCC in the high suction by the vapor equilibrium method shows that the water content is almost zero when the suction is close to 1 000 MPa. Based on the result of expanded soils by using filter paper, when SWCC is expressed with degree of saturation and suction relation, SWCC with higher dry density is on the upper side in the relatively low suction range, and the dry density has no effect on SWCC in the relatively high suction range.