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30 April 2014, Volume 19 Issue 2 Previous Issue    Next Issue

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Limit Analysis for Reinforced Concrete Rectangular Members Under Bending, Shear and Torsion CHEN Xia* (陈 溪), LIU Xi-lab (刘西拉) 2014, 19 (2):  129-138.  doi: 10.1007/s12204-014-1481-y Abstract ( 809 )   The ultimate strength of reinforced concrete (RC) rectangular members subjected to combined bending, shear and torsion is obtained from the limit analysis proposed in the present paper. Based on a warped failure surface determined by external loads, and a reasonable assumed stress distribution balancing external loads but not violating the yield condition, the bending-shear-torsion interaction can be derived from equilibrium conditions. According to the definition of lower-bound theorem in limit analysis, the calculated ultimate loads will be carried safely by the structure. The present method is a simple approach to obtain carrying capacities for RC elements under complex external loads. After comparing with the test results, a good agreement has been observed. The present method can be extended to explain the failure mechanism of RC members subjected to axial loads, and it is possible to develop a simple unified theory of RC members for engineering. References | Related Articles | Metrics

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Effects of Temperature Variations on Safety of Reinforced Concrete Structures During Construction HUANG Ke-feng* (黄科锋), LIU Xi-la (刘西拉) 2014, 19 (2):  139-145.  doi: 10.1007/s12204-014-1482-x Abstract ( 586 )   Since 1960s, many research works on the reinforced concrete structure have been published and some concise and practical calculation methods for safety control during construction have been achieved. The reinforced concrete structure during construction is a time-dependent structure which consists of a partly completed structure and a formwork-shore system. Experience shows that the most critical condition of the time-dependent structure may happen when the formwork-shore system is partly removed or reset and accidents may occur. In the present paper, effect of ambient temperature variation between day and night is considered, new structural models for reinforced concrete frames, slab-column systems and shear wall structures are proposed, and a new software named Safety Analysis During Construction Considering Temperature (SACT) is also introduced. Compared with on-site measurements, the software SACT is validated for application on construction site. References | Related Articles | Metrics

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Dynamic Model of Underwater Snake-Like Robot Using Kane’s Method YANG Ke (杨 柯), WANG Xu-yang* (王旭阳), GE Tong (葛 彤), WU Chao (吴 超) 2014, 19 (2):  146-154.  doi: 10.1007/s12204-014-1483-9 Abstract ( 823 )   In this paper, a dynamic model for an underwater snake-like robot is developed based on Kane’s dynamic equations. This methodology allows construction of the dynamic model simply and incrementally. The partial velocity is deduced. The forces which contribute to dynamics are determined by Kane’s approach. The generalized active forces and the generalized inertia forces are deduced. The model developed in this paper includes inertia force, inertia moment, gravity, control torques, and three major hydrodynamic forces: added mass, profile drag and buoyancy. The equations of hydrodynamic forces are deduced. Kane’s method provides a direct approach for incorporating external environmental forces into the model. The dynamic model developed in this paper is obtained in a closed form which is well suited for control purposes. It is also computationally efficient and has physical insight into what forces really influence the system dynamics. The simulation result shows that the proposed method is feasible. References | Related Articles | Metrics

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Multiobjective Particle Swarm Optimization Without the Personal Best WANG Ying-lin1,2 (王英林), XU He-ming2* (徐鹤鸣) 2014, 19 (2):  155-159.  doi: 10.1007/s12204-014-1484-8 Abstract ( 842 )   The personal best is an interesting topic, but little work has focused on whether it is still efficient for multiobjective particle swarm optimization. In dealing with single objective optimization problems, a single global best exists, so the personal best provides optimal diversity to prevent premature convergence. But in multiobjective optimization problems, the diversity provided by the personal best is less optimal, whereas the global archive contains a series of global bests, thus provides optimal diversity. If the algorithm excluding the personal best provides sufficient randomness, the personal best becomes worthless. Therefore we propose no personal best strategy that no longer uses the personal best when the global archive exceeds the population size. Experimental results validate the efficiency of our strategy. References | Related Articles | Metrics

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A Dynamic Model of an Underwater Quadruped Walking Robot Using Kane’s Method YANG Ke (杨 柯), WANG Xu-yang* (王旭阳), GE Tong (葛 彤), WU Chao (吴 超) 2014, 19 (2):  160-168.  doi: 10.1007/s12204-014-1485-7 Abstract ( 836 )   In this paper, the kinematics and dynamics of an underwater quadruped walking robot were derived based on Kane dynamic equations. This methodology allows construction of the dynamic model simply and incrementally. The velocity and angular velocity components of an underwater quadruped walking robot were served as the generalized velocities. The forces which contribute to dynamics of an underwater quadruped walking robot were determined by Kane’s approach. The equations of hydrodynamic forces of an underwater quadruped walking robot were deduced. Hydrodynamic coefficients were determined by experiments. The dynamic model was established by obtaining the generalized active forces and the generalized inertia forces. Numerical simulations of the walking behavior on underwater flat ground were implemented to verify the dynamic model of an underwater quadruped walking robot. Simulation results show that the dynamic model is correct. References | Related Articles | Metrics

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A Standard Cell-Based Leakage Power Analysis Attack Countermeasure Using Symmetric Dual-Rail Logic ZHU Nian-hao* (朱念好), ZHOU Yu-jie (周玉洁), LIU Hong-ming (刘红明) 2014, 19 (2):  169-172.  doi: 10.1007/s12204-014-1486-6 Abstract ( 758 )   Leakage power analysis (LPA) attacks aim at finding the secret key of a cryptographic device from measurements of its static (leakage) power. This novel power analysis attacks take advantage of the dependence of the leakage power of complementary metal oxide semiconductor (CMOS) integrated circuits on the data they process. This paper proposes symmetric dual-rail logic (SDRL), a standard cell LPA attack countermeasure that theoretically resists the LPA attacks. The technique combines standard building blocks to make new compound standard cells, which are close to constant leakage power consumption. Experiment results show SDRL is a promising approach to implement an LPA-resistant crypto processor. References | Related Articles | Metrics

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Pragmatic Physical Layer Abstraction Method Based on Bit-LLR-Wise Exponential Effective SNR Mapping for Bit Interleaved Coded Orthogonal Frequency Division Multiplexing System LI Meng-shi* (李孟实), YU Hui (俞 晖), LUO Han-wen (罗汉文), XU You-yun (徐友云) 2014, 19 (2):  173-180.  doi: 10.1007/s12204-014-1487-5 Abstract ( 733 )   In this paper, we analyze the physical layer abstraction for bit interleaved coded orthogonal frequency division multiplexing (BIC-OFDM) system from a parallel bit channel perspective. By combining the exponential effective SNR (signal-to-noise ratio) mapping (EESM) with the maximum a posteriori (MAP) algorithm, a bit LLR (log-likelihood ratio) wise EESM (BL-EESM) method is proposed. This method can abstract the link performance with high accuracy, especially for the case when channel estimation is imperfect. Afterward, the BL-EESM method is simplified by utilizing the non-linear quantization idea, which can reduce the times of exponential operation by two orders of magnitude at wide system bandwidth, yet shows little loss in accuracy. Our proposal can be applied to both system level simulations to save the time consumption and to practical terminals to facilitate the adaptive modulation and coding (AMC) procedure, bringing about throughput improvement at low hardware cost. References | Related Articles | Metrics

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Target Tracking in Standoff Jammer Using Unscented Kalman Filter and Particle Fiter with Negative Information HOU Jing* (侯 静), JING Zhan-rong (景占荣), YANG Yan (羊 彦) 2014, 19 (2):  181-189.  doi: 10.1007/s12204-014-1488-4 Abstract ( 666 )   To handle the problem of target tracking in the presence of standoff jamming (SOJ), a Gaussian sum unscented Kalman filter (GSUKF) and a Gaussian sum particle filter (GSPF) using negative information (scans or dwells with no measurements) are implemented separately in this paper. The Gaussian sum likelihood which is derived from a sensor model accounting for both the positive and the negative information is used. GSUKF is implemented by fusing the state estimate of two or three UKF filters with proper weights which are explicitly derived in this paper. Other than GSUKF, the Gaussian sum likelihood is directly used in the weight update of the GSPF. Their performances are evaluated by comparison with the Gaussian sum extended Kalman filter (GSEKF) implementation. Simulation results show that GSPF outperforms the other filters in terms of track loss and track accuracy at the cost of large computation complexity. GSUKF and GSEKF have comparable performance; the superiority of one over another is scenario dependent. References | Related Articles | Metrics

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Research on Function Based Method for Bio-Inspiration Knowledge Modeling and Transformation GU Chao-chen (谷朝臣), HU Jie* (胡 洁), PENG Ying-hong (彭颖红) 2014, 19 (2):  190-198.  doi: 10.1007/s12204-014-1489-3 Abstract ( 673 )   Biological inspirations are good design mimicry resources. This paper proposes a function based approach for modeling and transformation of bio-inspiration design knowledge. A general functional modeling method for biological domain and engineering domain design knowledge is introduced. Functional similarity based bio-inspiration transformation between biological domain and engineering domain is proposed. The biological function topology transfer and analog solution recomposition are also discussed in this paper. References | Related Articles | Metrics

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PSCAD Based Multi-infeed HVDC System Simulation Validated by a Recorded Fault ZHANG Xiao-hu* (张啸虎), BAI Jia-lin (白加林), CHEN Chen (陈 陈) 2014, 19 (2):  199-204.  doi: 10.1007/s12204-014-1490-x Abstract ( 695 )   More and more high voltage direct current (HVDC) converters are being located in a load area in the Yangtze River Delta Region in China. It’s large transmission capacity and intensive placement are hardly seen in other countries. Accurate and reliable study tools and methods are extremely needed for power system engineers and researchers to deal with such problems which were never met before and otherwhere. A novel approach on electromagnetic modeling of alternating current / direct current (AC/DC) system is proposed and simulation is carried out to replay a real AC 3-phase to ground fault on a multi-infeed high voltage direct current (MIHVDC) system. AC system is specially simplified. Dynamic models and real parameters are adopted in main AC/DC equipments concerned and retained. Modeling and simulation are based on the power system computer aided design/electro-magnetic transient in direct current (PSCAD/EMTDC) system software package. Comparisons between simulation results and the records from the fault recorders are studied including both AC and DC quantities. References | Related Articles | Metrics

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Containership Structural Design and Optimization Based on Knowledge-Based Engineering and Gaussian Process CUI Jin-ju (崔进举), WANG De-yu* (王德禹), VLAHOPOULOS Nickolas 2014, 19 (2):  205-218.  doi: 10.1007/s12204-014-1491-9 Abstract ( 633 )   Knowledge-based engineering (KBE) has made success in automobile and molding design industry, and it is introduced into the ship structural design in this paper. From the implementation of KBE, the deterministic design solutions for both rules design method (RDM) and interpolation design method (IDM) are generated. The corresponding finite element model is generated. Gaussian process (GP) is then employed to build the surrogate model for finite element analysis, in order to increase efficiency and maintain accuracy at the same time, and the multi-modal adaptive importance sampling method is adopted to calculate the corresponding structural reliability. An example is given to validate the proposed method. Finally, the reliabilities of the structures’ strength caused by uncertainty lying in water corrosion, static and wave moments are calculated, and the ship structures are optimized to resist the water corrosion by multi-island genetic algorithm. Deterministic design results from the RDM and IDM are compared with each separate robust design result. The proposed method shows great efficiency and accuracy. References | Related Articles | Metrics

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Scaling Analysis of Thermal-Hydraulics for Steam Generator Passive Heat Removal System ZHOU Yuan1,2* (周 源), LIN Meng1 (林 萌), CHEN Jin-bo1 (陈金波), WANG Han-lin1 (王汉林) 2014, 19 (2):  219-225.  doi: 10.1007/s12204-014-1492-8 Abstract ( 696 )   Steam generator passive heat removal system (SG-PHRS) is used as a passively safe mode to provide decay heat removal in some advanced pressurized water reactors. Due to the structure characteristics of steam generator (SG), there are two natural circulation loops coupling in SG-PHRS in case of a safety-related event. The existing natural circulation scaling criteria could be used to simulate the natural circulation inside SG. Two-phase natural circulation loop is studied carefully, and the dominant effects of SG on behaviors of natural circulation in passive heat removal system are presented. Based on the understanding of SG-PHRS operation, system pressure transient scaling and two-phase natural circulation scaling are analyzed by establishing the relevant continuity, integral momentum and energy equations in one-dimensional area-averaged forms. With modified equations, similarity criteria for SG-PHRS are obtained for engineering application. In addition, equal height simulation and reduced height simulation are studied. References | Related Articles | Metrics

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Research on Numerical Wave Tank Based on the Improved Moving-Particle Semi-Implicit Method with Large Eddy Simulation YU Qiana (余 谦), ZHANG Huai-xina,b* (张怀新), SUN Xue-yaoa (孙学尧) 2014, 19 (2):  226-232.  doi: 10.1007/s12204-014-1493-7 Abstract ( 477 )   Moving-particle semi-implicit (MPS) method is a new mesh-free numerical method based on Lagrangian particle. In this paper, MPS method is applied to the study on numerical wave tank. For the purpose of simulating numerical wave, we combine the MPS method with large eddy simulation (LES) which can simulate the turbulence in the flow. The intense pressure fluctuation is a significant shortcoming in MPS method. So, we improve the original MPS method by using a new pressure Poisson equation to ease the pressure fluctuation. Divergencefree condition representing fluid incompressible is used to calculate pressure smoothly. Then, area-time average technique is used to deal with the calculation. With these improvements, the modified MPS-LES method is applied to the simulation of numerical wave. As a contrast, we also use the original MPS-LES method to simulate the wave in a numerical wave tank. The result shows that the new method is better than the original MPS-LES method. References | Related Articles | Metrics

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Rigid-Liquid-Flexible Dynamic Formulation for a Two-Dimensional Tank Undergoing Translational and Rotational Motion FAN Wei (樊 伟), LIU Jin-yang* (刘锦阳) 2014, 19 (2):  233-240.  doi: 10.1007/s12204-014-1494-6 Abstract ( 553 )   Considering rigid-liquid-flexible coupling effect, dynamic formulation for a two-dimensional rectangular tank with liquid sloshing connected to a flexible beam is proposed. Differing from the traditional formulation which considered either the rotational motion or the translational motion of the tank, this formulation can be applied for rigid-liquid-flexible coupling dynamic analysis of tank undergoing translational and rotational motion based on the theorem of momentum and the theorem of moment of momentum. Furthermore, stiffening terms are included in the dynamics equations of the flexible beam. Firstly, the dynamic equations of the rigid-liquid coupling system and the flexible beam are derived, respectively, and then by introducing the Lagrange-multipliers, the rigid-liquid-flexible coupling equations can be combined with acceleration constraint equations. Finally, the mix differential-algebraic equations are solved to investigate the rigid-liquid-flexible coupling dynamic performance of the system. References | Related Articles | Metrics

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Mathematical Approach for Fleet Planning Under Complicated Circumstances YANG Qiu-ping1* (杨秋平), ZHANG Hao2 (张 皞), SANG Hui-yun2 (桑惠云), XIE Xin-lian2 (谢新连) 2014, 19 (2):  241-250.  doi: 10.1007/s12204-014-1495-5 Abstract ( 461 )   In order to facilitate the scientific management of large-sized shipping companies, fleet planning under complicated circumstances has been studied. Based on multiple influencing factors such as the techno-economic status of ships, the investment capacity of company, the possible purchase of new ships, the buying/selling of second-hand vessels and the chartering/renting of ships, a mixed-integer programming model for fleet planning has been established. A large-sized shipping company is utilized to make an empirical study, and Benders decomposition algorithm is employed to test the applicability of the proposed model. The result shows that the model is capable for multi-route, multi-ship and large-scaled fleet planning and thus helpful to support the decision making of large-sized shipping companies. References | Related Articles | Metrics

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Research on Newly Urbanized Towns and Districts in China LIU Xin-jing (刘新静), YU Wei* (于 炜), WANG Xiao-jing* (王晓静), SHENG Rong (盛 蓉)，ZHANG Shu-cheng (张书成), LIU Shi-lin (刘士林) 2014, 19 (2):  251-256.  doi: 10.1007/s12204-014-1496-4 Abstract ( 505 )   Since the last decade the central government endeavors to promote large scale of urbanization in China. Lots of new urban towns and districts are taking shape. Outline of the 12th Five-year Plan released by the central government points out that the new towns and districts are to be regulated. But few researches are considering the new towns and districts especially in the spatial distributive pattern and status in China. Given this situation this paper, after sorting out the world-wide research and development of new urban towns and districts, gives definitions of broad and narrow meanings. Based on the broad meaning definition, the database of new towns and districts in China is established. This paper then conducts a preliminary analysis of the new towns and districts. Then the two-step work plan and the advices are also proposed to further improve the research and practice of its kind in China. References | Related Articles | Metrics