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    20 December 2015, Volume 20 Issue 6 Previous Issue    Next Issue

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    Research article
    Compliant Assembly Modeling and Deformation Analysis Considering Macro Residual Stress in Engineering Component
    Li-na ZHANG, Hua WANG, Shu-hui LI
    2015, 20 (6):  641-648.  doi: 10.1007/s12204-015-1671-2
    Abstract ( 231 )   HTML ( 787 )  

    Based on the manufacturing history chain, a component’s macro residual stress is introduced to the subsequent assembly model. In the simulated method, the simulation cost is saved via mapping the bulk stress profile directly to the component compared to our previous study. It thus facilitates the finite element analysis (FEA) which takes the component location in blank and the thickness of blank as two influence parameters. The methodology is proved to be feasible by the validation experiment designed for a typical assembly structure from the aerospace industry. The results show that the bulk stress originating from material preparation affects the downstream large-scale assembly deformation. The investigation of this research helps systematically to improve compliant assembly precision.

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    A Wireless Video Capsule Endoscopy System: Design and Realization
    Bing-quan ZHU, Guo-zheng YAN, Gang LIU, Wen-ming XU
    2015, 20 (6):  649-653.  doi: 10.1007/s12204-015-1672-1
    Abstract ( 240 )   HTML ( 531 )  

    Wireless capsule endoscopy (CE), an image inspection technique, has been an important advancement in the diagnosis of gastrointestinal (GI) tract diseases. A video capsule endoscopy (VCE) system is analyzed in this study. A complementary metal oxide semiconductor (CMOS) analog image sensor is adopted, and other illumination, communication and energy modules are designed for functional realization. Measuring only ?11 mm×25 mm, the VCE has a total power consumption of 52.5 mW, which enables it to work continuously for 8 h. The in vivo experiment on a living pig indicates that a clear video with high frame rate of 30 f/s can be obtained.

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    Price-Based Power Control Algorithm in Cognitive Radio Networks Based on Monotone Optimization
    Zheng-qiang WANG, Ling-ge2 JIANG, Chen HE
    2015, 20 (6):  654-659.  doi: 10.1007/s12204-015-1673-0
    Abstract ( 239 )   HTML ( 567 )  

    This paper considers a price-based power control problem in the cognitive radio networks (CRNs). The primary user (PU) can admit secondary users (SUs) to access if their interference powers are all under the interference power constraint. In order to access the spectrum, the SUs need to pay for their interference power. The PU first decides the price for each SU to maximize its revenue. Then, each SU controls its transmit power to maximize its revenue based on a non-cooperative game. The interaction between the PU and the SUs is modeled as a Stackelberg game. Using the backward induction, a revenue function of the PU is expressed as a non-convex function of the transmit power of the SUs. To find the optimal price for the PU, we rewrite the revenue maximization problem of the PU as a monotone optimization by variable substitution. Based on the monotone optimization, a novel price-based power control algorithm is proposed. Simulation results show the convergence and the effectiveness of the proposed algorithm compared to the non-uniform pricing algorithm.

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    A Generalized Two-Level Bregman Method with Dictionary Updating for Non-Convex Magnetic Resonance Imaging Reconstruction
    Ming-hui ZHANG, Xiao-yang HE, Shen-yuan DU, Qie-gen* LIU
    2015, 20 (6):  660-669.  doi: 10.1007/s12204-015-1674-z
    Abstract ( 204 )   HTML ( 220 )  

    In recent years, it has shown that a generalized thresholding algorithm is useful for inverse problems with sparsity constraints. The generalized thresholding minimizes the non-convex p-norm based function with p<1, and it penalizes small coefficients over a wider range meanwhile applies less bias to the larger coefficients. In this work, on the basis of two-level Bregman method with dictionary updating (TBMDU), we use the modified thresholding to minimize the non-convex function and propose the generalized TBMDU (GTBMDU) algorithm. The experimental results on magnetic resonance (MR) image simulations and real MR data, under a variety of sampling trajectories and acceleration factors, consistently demonstrate that the proposed algorithm can efficiently reconstruct the MR images and present advantages over the previous soft thresholding approaches.

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    Admission Control Scheme for Handover Service in High-Speed Train Communication System
    Yi-sheng ZHAO, Hong JI, Zhong-hui CHEN
    2015, 20 (6):  670-675.  doi: 10.1007/s12204-015-1675-y
    Abstract ( 234 )   HTML ( 215 )  

    Admission control in high-speed train communication system is quite different from admission control in traditional cellular networks. Conventional admission control strategies cannot be directly applied to this special communication scenario. In this paper, the problem of admission control for handover service is investigated in high-speed train communication environment. An admission control scheme considering bit error rate (BER) and bandwidth borrowing strategy is proposed. On the basis of admission control decision rule taking BER into account, a part of bandwidth obtained by compressing variable rate service in the networks is provided for handover services. The admission control scheme can admit handover services as more as possible while it guarantees the lowest data rate of different services in the networks. Simulation results show that the proposed admission control scheme has a better performance than existing admission control schemes.

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    Outage Performance of Amplify-and-Forward Multiple-Input Multiple-Output Relay Networks with Outdated Channel State Information and Co-channel Interference
    Yin-jie SU, Ling-ge JIANG, Chen HE
    2015, 20 (6):  676-682.  doi: 10.1007/s12204-015-1676-x
    Abstract ( 197 )   HTML ( 218 )  

    In this paper, we investigate the outage performance of a dual-hop amplify-and-forward (AF) multiple-input multiple-output (MIMO) relay network, considering beamforming transmission with outdated channel state information (CSI) and an arbitrary number of co-channel interferers at both the relay and the destination. The exact closed-form expression for the outage probability is derived, and the asymptotic behavior of the outage probability is also presented to provide further insights into the system performance. Our results show that the system suffers a diversity gain loss caused by the outdated CSI, and the interference only degrade the coding gain of the system. Moreover, increasing antennas can achieve more performance gains, however, the gains decrease as the delay of the CSI increases.

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    Elasto-Plastic Modeling of Soft Soil Considering Degradation of Stiffness
    Hao ZHANG, Qiu-shi CHEN, Jin-jian CHEN, Jian-hua WANG
    2015, 20 (6):  683-689.  doi: 10.1007/s12204-015-1677-9
    Abstract ( 180 )   HTML ( 218 )  

    The stiffness has a large influence on the behavior of soils. Its value is affected by some of the soils properties, such as the over consolidated ratio (OCR), the effective normal stress, and the plasticity index etc. In this paper, the numerical modeling of soft soils was carried out using an improved elasto-plastic S-clay1 model accounting for degradation of stiffness. The relation between the stiffness and the shear strain was established based on a large number of experimental data. The effects of strain-dependent stiffness of normally consolidated soils and over consolidated soils on the stress-strain behavior were studied through a comparison of the simulations with the experimental results of undrained triaxial compression tests. The results show that the behaviors of soils can be well predicted with the improved constitutive model, particularly before the peak stress.

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    Numerical Simulation of Drawdown and Land Deformation in Pumping-Recovery Tests Performed on a Circular Excavation
    Kai-yong HUANG, Xiang-lian ZHOU, Jian-hua WANG
    2015, 20 (6):  690-695.  doi: 10.1007/s12204-015-1678-8
    Abstract ( 203 )   HTML ( 243 )  

    A mathematical model, which not only fully couples fluid flow and solid skeleton deformation in unsaturated porous elastic media but also considers deformable diaphragm walls, is formulated in axially symmetric cylindrical coordinates for drawdown and land deformation. Based on this model, pumping-recovery tests in various conditions are numerically simulated to reveal the effects of elastic modulus of soil $E$ and initial saturated hydraulic conductivity $K_{\rm sat0} $ on hydraulic head and land deformation. The heterogeneity with respect to $E$ and $K_{\rm sat0} $ is separately taken into account. Large elastic modulus of soil contributes to both dewatering process and deformation control. Either large or small initial saturated hydraulic conductivity may cause relatively high groundwater table, while the larger one leads to smaller displacements.

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    Application of Back Analysis on Laterally Loaded Single Pile
    Feng WU, Jing-hai GONG, Kun FU
    2015, 20 (6):  696-702.  doi: 10.1007/s12204-015-1679-7
    Abstract ( 207 )   HTML ( 269 )  

    In views of the limitations of the existing methods for calculating the pile foundation capacity, a back analysis approach of the $m$-value is introduced. In order to consider the sensitivity of pile behavior to the $m$-value, the relationships between the applied horizontal loads at pile head and the corresponding $m$-value along with the pile stiffness changes are studied. Based on statistics data from the extensive in-situ tests, the back analysis results suggest an exponential expression for the $m$-value in various soil conditions and horizontal displacements at pile head. This method is capable of providing an accurate $m$-value in calculating the pile responses under lateral loads.

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    Experimental Investigation into Low-Velocity Water Entry of Cylinder Structure
    Wen-hua CHU, Feng FENG, Jian ZHANG
    2015, 20 (6):  703-712.  doi: 10.1007/s12204-015-1680-1
    Abstract ( 245 )   HTML ( 262 )  

    The process of low-velocity water entry is utilized on a large scale for the military and engineering purposes. However, there are rarely systematic experimental investigations into the low-velocity water entry of cylinder structure for reference. In order to obtain typical phenomena and relevant laws, we design a set of experimental facilities with adjustable parameters and better repeatability to study this process with a high-speed photography system. The influences of cylinder radius, initial velocity and entry angle on the process of low-velocity water entry are tested. Results show that six typical phases exist in this process: structure submersion, necking, cavity formation, cavity abscission, spray at the free surface and jet formation. Three factors mentioned above are key parameters and influence the process in different degrees, and some laws obtained in this paper have a reasonable agreement with the theoretical results. Our results provide references for the relevant numerical researches and engineering applications.

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    Study on the Characteristic of a Forced Pitching Supercavitating Vehicle
    Zhan-cheng PAN, Chuan-jing LU, Ying CHEN
    2015, 20 (6):  713-720.  doi: 10.1007/s12204-015-1681-0
    Abstract ( 217 )   HTML ( 211 )  

    During the cruising of a supercavitating vehicle, the relative motion between the supercavity and the vehicle has a significant effect on the stability of the supercavity and the trajectory of the vehicle. In this paper, periodically forced pitching of a supercavitating vehicle is investigated numerically by a dynamic mesh method. The simulated result of the flow field around a pitching ventilated supercavitating vehicle in a water tunnel is compared with the experimental result. The evolution of the cavity morphology, the pressure distribution and the hydrodynamics of the vehicle are in good agreement with the experimental data. The effect of different pitching amplitudes and frequencies is studied. Also, the effect of the tunnel wall and the bracing structure is analyzed.

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    Nonlinear Pitch Control of an Underwater Glider Based on Adaptive Backstepping Approach
    Jun-liang CAO, Bao-heng YAO, Lian LIAN
    2015, 20 (6):  729-734.  doi: 10.1007/s12204-015-1683-y
    Abstract ( 230 )   HTML ( 214 )  

    Underwater gliders are highly efficient and long-ranged autonomous underwater vehicles. The typical dynamic modeling in the vertical plane is of multi-input multi-output (MIMO), which is underactuated while easily affected by the ambient environment. To resolve the problems of MIMO, the dynamic model is transformed into a single-input single-output (SISO) system with two dubious parameters, and an adaptive backstepping controller is designed and applied in this paper. A Lyapunov function has been established with the total energy of the system converged in the controller. Contrast result of simulation has demonstrated that the derived nonlinear controller has higher tracking precision and faster response than the proportional-integral-derivative (PID) control method, which indicates its excellent capability to deal with the controlling problems of underwater gliders.

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    Free Vibration Analysis of Cylindrical and Rectangular Sandwich Panels with a Functionally Graded Core
    Hua-dong LI, Xi ZHU, Zhi-yuan MEI, Ying-jun ZHANG
    2015, 20 (6):  735-742.  doi: 10.1007/s12204-015-1684-x
    Abstract ( 229 )   HTML ( 412 )  

    Based on the Reissner assumptions, the free vibration analysis of simply supported cylindrical and rectangular sandwich panels with isotropic face sheets and a functionally graded core is concerned. Firstly, the expressions of the displacements, stresses and internal forces are presented according to the constitutive relations and stress states of the core and face sheets. Then, the dynamic stability and compatibility equations are given for cylindrical sandwich panels with functionally graded core, elastic modulus and density in which vary continuously in the thickness direction. Finally, the proposed solutions are validated by comparing the results of degenerate example with classical solutions, and a numerical analysis is performed on the example of simply supported cylindrical and rectangular sandwich panels. The elastic modulus and density of the functionally graded core are assumed to be graded by a power law distribution of volume fractions of the constituents, and the Poisson ratio is held constant. The effects of the distribution of functionally graded core's properties, the thickness-side ratios and ratio of radius $(R)$ to length $(l)$ $\kappa =R/l$ are also examined.

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    Fairness-Embedded Governmental Coordination by Dominated Retailer in Heterogeneous Circumstance
    Guang-hua HAN, Xu-jin PU, Geng-xi DAI
    2015, 20 (6):  743-751.  doi: 10.1007/s12204-015-1685-9
    Abstract ( 184 )   HTML ( 298 )  

    Market demand is positively affected by the investments in marketing and quality improvement. In a retailer dominated supply chain, the manufacturer takes charge of product quality improvement and the retailer focuses on marketing. The investments on cooperative marketing and product quality improvement in supply chains are known to be heterogeneous investment, where the manufacturer (he) is fairness sensitive and the retailer (she) is fairness insensitive. Due to the manufacturer's conservative investment resulting from this sensitivity of fairness, the retailer shares a proportion of the manufacturer's investment to increase his investment. It is found that the manufacturer's fairness negatively affects his investment and the manufacturer sometimes tends to be a ‘free rider' under decentralized decision patterns, which lead to a poor supply chain performance. This study also proves that both the manufacturer and the retailer are motivated to cooperate under centralized patterns, where the retailer's objective is additional expected profit and the manufacturer's objective is enlarging his utility. Based on the comparison of equilibrium solutions in decentralized and centralized patterns, this study suggests the range of cost-sharing proportion for supply chain coordination. The example shows the effectiveness of the provided supply chain coordination.

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    Optimal Last Stock of Substitutive Service Parts
    Lin QUAN, Qi-cai LI
    2015, 20 (6):  752-757.  doi: 10.1007/s12204-015-1686-8
    Abstract ( 237 )   HTML ( 387 )  

    This paper focuses on the last stock problem of substitutive service parts, which is a hot problem in practice. Considering that a firm faces two types of service parts with a certain substitution coefficient, we study the optimization problem of minimizing the total expected cost. Using the non-linear programming theory and method, we find the optimal preserved quantities for the optimization problem. The relation between the product substitution characteristic and the total cost of service parts is analyzed. And an example is given to show the application of our model.

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    Research on Modeling Approach of Brain Function Network Based on Anatomical Distance
    Yan-li YANG, Hao GUO, Jun-jie CHEN, Hai-fang LI
    2015, 20 (6):  758-762.  doi: 10.1007/s12204-015-1687-7
    Abstract ( 199 )   HTML ( 407 )  

    The number of common neighbor between nodes is applied to the modeling of resting-state brain function network in order to analyze the effect of anatomical distance on the modeling of resting-state brain function network. Three models based on anatomical distance, the number of common neighbor, or anatomical distance and the number of common neighbor are designed. Basing on residuals creates the evaluation criteria for selecting the optimal brain function model network in each class model. The model is selected to simulate the human real brain function network by comparison with real data functional magnetic resonance imaging (fMRI) network. Finally, the result shows that the best model only is based on anatomical distance.

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