Table of Content

30 October 2012, Volume 18 Issue 5

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DNA Elastic Nonlinearities: Remarkable Combination of  High Compliance and High Rigidity

XIAO Heng

2012, 18(5):  441-447.  doi:10.3969/j.issn.1007-2861.2012.05.001

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DNA molecules perform biological functions via large elastic deformations and conformational changes in their interactions with the cellular machinery. Accordingly, adequate characterization of DNA elasticity is instrumental to an in-depth understanding of DNA functions. Because of their profound complexity, however, nonlinear features inherent in DNA elasticity remains to be uncovered in a direct and full sense, and a unified and explicit characterization over the entire stretch range is still unavailable. This paper suggests that DNA elastic nonlinearities may be understood by combining linear springs with high compliance and high rigidity. This finding uncovers the inherent geometrical feature in profound nonlinearities of DNA elasticity, and leads to a unified and explicit force-extension formula up to breaking. This formula reveals for the first time a complete set of characteristic constants for DNA elasticity and is shown to provide a unified characterization for both double- and single-stranded DNA molecules. Results are presented in a straightforward and broad sense independent of any substructural details.

Road Network Structural Reliability Based on Mobility Reliability

XU Xu,FU Rong

2012, 18(5):  448-453.  doi:10.3969/j.issn.1007-2861.2012.05.002

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Based on traditional study of road structural reliability, this paper introduces a method for the calculation of road network reliability to provide a way of studying road network structural reliability. Meanwhile, in view of recent studies on reliability and mobility reliability, this paper analyzes the effect of traffic flow assignment during traffic congestion on road network reliability.

Fast Inpainting Algorithm for Kinect Depth Map

WANG Kui1,AN Ping1,2,ZHANG Zhao-yang1,2,CHENG Hao1,LI He-jian1

2012, 18(5):  454-458.  doi:10.3969/j.issn.1007-2861.2012.05.003

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Depth extraction is a key step in 3D video system based on texture plus depth. Real application systems require high efficiency and fast depth extraction. This paper presents a fast inpainting algorithm for Kinect depth map. This paper clips and aligns the origin color and depth images captured by Kinect, and partially fill holes in the clipped depth image using a background based method. Then this paper uses a fast inpainting algorithm based on color match to fill the remaining holes in the depth image to obtain a better depth image. Experimental results show that the proposed algorithm can efficiently repair errors in the original depth map such as holes caused by occlusion. Finally we obtain a smooth depth map with clear edges. The processing speed can reach 25~30 frame/s by using an ordinary desktop computer to realize real-time depth map extraction.

Dual-Band Bandpass Filter Using Stub-Loaded Multiple Stepped-Impedance Resonators

HUANG Chun-yan,XIAO Zhong-yin,KOU Xin,CHU Jun-jun,LI Hao

2012, 18(5):  459-463.  doi:10.3969/j.issn.1007-2861.2012.05.004

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A novel dual-band filter using stub-loaded multiple stepped-impedance resonators is proposed. This filter can control each center frequency independently. In order to get more degrees of freedom, the microstrip filter uses a multiple stepped-impedance structure. Due to symmetry of the structure, the traditional even-odd mode analysis can be used. A dual-band filter can easily be obtained by adjusting the impedance ratio and electrical length. The dual-band filter with 3 dB relative bandwidths of 6% and 2.6% can be applied to 2.44 GHz (WLAN) and 3.50 GHz (WiMAX), respectively. Simulation results agree well with measurements.

Improved VIE Rainfall Retrieval Algorithm Based on SAR Measurements

ZHENG He,XIE Ya-nan,WAN Zhi-long,LIU Wen-yuan

2012, 18(5):  464-469.  doi:10.3969/j.issn.1007-2861.2012.05.005

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This paper proposes a new type of rainfall retrieval algorithm, which improves the method using the Volterra integral equation (VIE). The proposed algorithm makes pre-analysis on the data received by synthetic aperture radar to get information such as the rainfall start point and the scope of the rain. The VIE retrieval algorithm is then applied in a short distance to get information of the rain distribution. Further analysis is then made on the information obtained in the previous step to find parameters such as shape of the rain and the rain rate. According to the most commonly studied rainfall distributions that are symmetric, the rainfall distribution is obtained. Simulation results show that the proposed algorithm is effective and efficient, with high accuracy.

Localization of RSSI-Based Indoor WSN Nodes

JIN Yan-liang,XUE Yong,ZHANG Yong

2012, 18(5):  470-474.  doi:10.3969/j.issn.1007-2861.2012.05.006

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This paper analyzes several conditions of received signal strength indication (RSSI) indoor node localization based on experiments. An RSSI indoor propagation model is established using an indoor wireless communication model and the measured data. Different positioning precision of the unknown nodes in different locations are compared. The particle swarm optimization (PSO) algorithm is used to optimize the locating results. Experimental results show that the PSO algorithm has good performance. The influence of different number of beacon nodes is analyzed for the node positioning accuracy. The experiment shows that the beacon node number affects the positioning accuracy to a certain extent. When there are too many beacon nodes, reliable ones should be chosen as to ensure the localization precision.

Design of Wideband Dual-Band Dual-Polarized Single-Layer Perforated SAR Antenna

MENG Zi-rui,ZHONG Shun-shi,SUN Zhu,SHEN Wen-hui

2012, 18(5):  475-479.  doi:10.3969/j.issn.1007-2861.2012.05.007

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A novel L/C dual-band dual-polarized shared-aperture antenna with a single-layer perforated structure is proposed for synthetic aperture radar (SAR) applications. The aim is to broaden the impedance bandwidth in the lower L-band of the L/C shared-aperture SAR antenna. The antenna element has been simulated, fabricated and measured. The measurements show that the bandwidths, defined as reflection coefficient being less than or equal to -10 dB, is increased to 13.7% in the lower L-band, while that of the higher C-band reaches 17.0%. Experimental results have verified this design.

Tree Ordering According to Minimal Energies

WANG Wen-huan,XU Wei-wei

2012, 18(5):  480-483.  doi:10.3969/j.issn.1007-2861.2012.05.008

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Let T_n be a set of trees with n vertices. The increasing orders in terms of the minimal energies of the trees in T_n had been considered and two conjectures were proposed. The first one is the comparison of the energies of two graphs in T_n. The other is about the trees with the 10th to 12th minimal energies for n≥7 117 599. This paper proves that the two conjectures are true, and obtain the first 12 trees within T_n for n≥7 117 599.

Half-Discrete Hilbert Inequality with a Single Parameter

YANG Bi-cheng

2012, 18(5):  484-488.  doi:10.3969/j.issn.1007-2861.2012.05.009

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Using the weight coefficient method and parameterization, a half-discrete Hilbert inequality with a best constant factor and a parameter λ∈(0,4］ is given. Its best extension with multi-parameters and equivalent forms are also considered.

Analysis and Application of Thermal Lattice Boltzmann Method

CHEN Jie,QIAN Yue-hong

2012, 18(5):  489-495.  doi:10.3969/j.issn.1007-2861.2012.05.010

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Lattice Boltzmann method (LBM) is a mesoscale computational method based on the gas kinetic theory. For solving Fourier-Navier-Stokes equations, the thermal lattice model has attracted much research attention. This paper compares several thermal lattice models in terms of accuracy, stability and computational efficiency. The thermal flow in pore-scale porous is also studied using different thermal lattice models.

Existence of Solutions to a Dynamic Boundary Value Problem

WANG Yuan-di,SHI Ben-lei

2012, 18(5):  496-499.  doi:10.3969/j.issn.1007-2861.2012.05.011

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A dynamic boundary value problem of parabolic equation is investigated. Existence of classic solutions is proved by combining the Sobolev-Slobodeckij space theory and fixed point theorem.

Simulation System of a Production Line Based on Quest

ZHANG Xiao-guang,LIN Cai-xing,ZHAO Cui-lian

2012, 18(5):  500-505.  doi:10.3969/j.issn.1007-2861.2012.05.012

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With the development of computer simulation technology, digital production line logistics system receives increasingly more attention. Bottlenecks in a production line can be found in logistics simulation to avoid risk in the investment and construction. Logistics simulation is performed with the software Quest to achieve system optimization. The aim of simulation is to find bottlenecks in a production line and identify causes of the problem. The system configuration is optimized to meet certain optimization goals. Statistical parameters before and after configuration are compared to obtain an optimal solution.

Binocular Vision-Based Humanoid Manipulator Control for Service Robot

XU Yu-lin,YANG Yong-huan,LI Xin,CHEN Wan-mi,CHAO Yan-kai

2012, 18(5):  506-512.  doi:10.3969/j.issn.1007-2861.2012.05.013

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Inverse kinematics, object localization and manipulation are essential for service robots with manipulators to achieve various human-like tasks. Binocular vision is employed to interact with the environment in which the service robot works. This paper presents an approach for binocular based humanoid manipulation in a service robot system. An inverse kinematic solver is proposed to find all joint angles for a given position of the effectors on the manipulator. The target object is recognized according to segmented colors, and the 3D position computed using the stereo vision system. Having obtained the target position, the manipulator performs a blind grasp. Experimental results show effectiveness of the proposed methods.

Data Link Layer Design and Implementation Based on SPI Bus for Dual-Processor Communication

SUN Bin,HU Yue-li,WANG Kun

2012, 18(5):  513-518.  doi:10.3969/j.issn.1007-2861.2012.05.014

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This paper proposes a data link layer design method for dual-processor communication based on serial peripheral interface (SPI) bus. Advantages of the two-way SPI bus in this design include using less pins (only one line more than the SPI bus) and perfect data link layer protocol control. These can ensure transparent data transfer between the two processors. An automotive body bus controller with a display unit was used as an application. It uses ARM9 and S12 as dual-processors to achieve two-way communication. Implementation and application of the method are described. Experiments show that the protocol is effective in engineering practices, and provides a reference to other SPI applications.

Influence of Considering 3D Thermal Effects on Dynamic Characteristics of Tilting Pad Thrust Bearing

HE Jia-meng,WANG Xiao-jing,QI Gao-an,HUANG Min

2012, 18(5):  519-524.  doi:10.3969/j.issn.1007-2861.2012.05.015

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The dynamic characteristics of the line-supported tilting pad thrust bearing are studied by taking thermal effects into account. The generalized Reynolds equation, the complete 3D energy equation, the heat conduction equation of the pad, and the temperature viscosity relation are established to derive the stiffness and damping coefficient of the oil film on the tilting pad. It is shown that the thermal effects have significant influence on the dynamic characteristics of tilting thrust pads. Compared to the line-supported tilting pad without including the thermal effect, stiffness and damping coefficient of the oil film including the thermal effect increases so that it becomes closer to the actual operating conditions. With the increase of load and inlet temperature and the decrease of angular velocity, stiffness and the damping coefficient of the oil film will increase.

Analytical Solution of Harmonic Vibration of Saturated Soil and Lining System with Deeply Embedded Circular Tunnel

YANG Xiao,WEN Min-jie

2012, 18(5):  525-530.  doi:10.3969/j.issn.1007-2861.2012.05.016

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The dynamic behavior of harmonic vibrations of saturated viscoelastic soil and lining system with a deeply embedded circular tunnel is investigated in the frequency domain. Based on elasticity and the theory of porous medium, steady-state dynamic responses of the lining and saturated viscoelastic soil are given. Analytical expressions of displacement, stress and pore water pressure for steady-state vibration of the saturated soil and a lining system subject to a uniform harmonic load on the lining boundary are obtained under boundary conditions of the lining and continuity conditions on the interface between the saturated soil and the lining. Influence of the physical and geometric parameters on the dynamic characteristics of the system is examined. It is shown that permeability of pore water has a great influence on the system’s dynamic behavior. The responses to an impermeable system is much greater than those to a permeable system. Furthermore, for an impermeable system, the lining’s thickness has a remarkable influence on the system behavior, while influences of the interaction coefficient between soil skeleton and pore water, and the soil’s Poisson ratio on the system behavior are unnoticeable.

Mesomechanical Simulation of Push-Shear Tests on Coal Waste with Particle Flow Code

DUAN Wei1,2,ZHANG Meng-xi1

2012, 18(5):  531-538.  doi:10.3969/j.issn.1007-2861.2012.05.017

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Based on two dimensional particle flow code (PFC^2D), a horizontal push-shear test model of coal waste is established to simulate the push-shear tests that gangue have different compactness before and after improvement reflected by different gradation and porosity. The pushing force-displacement curves of the coal waste specimens are reproduced and verified by the PFC^2D model, and the difference in the curves is analyzed. The law of particle mobilization in push-shear tests is verified from the perspective of mesomechanics. The results show that the contact force in the model will transmit along the slip surface. Distribution of contact force after improvement presents inverted crescent-type. Furthermore, the angle between the direction of contact force and the horizontal in the model after improvement becomes larger, and the contact force concentrates in a narrower area. The slip surface is also determined in push-shear tests by means of the displacement vector chart.

Two-Dimensional FEM Analysis of Near Field Influence of Buffer Material Parameters on High Level Radioactive Nuclear Waste Repository

QIN Ai-fang,ZHAO Fei,ZHAO Xiao-long

2012, 18(5):  539-544.  doi:10.3969/j.issn.1007-2861.2012.05.018

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The FEBEX in-situ test for geological disposal of high-level radioactive nuclear waste is used as a calculation model. By changing the initial permeability, the initial suction and the air entry value, variation of saturation, and suction under the coupled thermo-hydro-mechanical (THM) action are analyzed using a Code-Bright program after the closure of nuclear waste repository. By analyzing sensitivity of the three parameters on these traits, valuable reference is presented for the selection of buffer materials of the nuclear waste repository.

Experimental of Bending Behavior of Circular Timber Beams Strengthened with CFRP Sheets

OUYANG Yu,LI You

2012, 18(5):  545-550.  doi:10.3969/j.issn.1007-2861.2012.05.019

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In practice, most wood beams to be repaired have already been damaged or degraded. It is necessary to study the structural performances of damaged wood beams reinforced by carbon fiber reinforced polymer (CFRP) sheets. Based on static tests of 8 damaged circular timber beams strengthened with CFRP sheets, bending behaviors are studied, including failure characteristics, ultimate bearing capacity, rigidity, and strain of timber section. The results show that CFRP sheets have a good strengthening effect for timber beams. The loading capacity of a timber beam reinforced by CFRP is effectively enhanced. The results are useful to practical design.