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28 February 2013, Volume 18 Issue 1 Previous IssueNext Issue
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Analysis of the Pencil of Conics with Double Complex Contact and Its Application to Camera Calibration CAI Shen1* (蔡棽), WANG Chen-hao1 (王宸昊), YAN Yan1,2 (阎炎), LIU Yun-cai1 (刘允才) 2013, 18 (1): 1-006. doi:10.1007/s12204-013-1361-x Abstract( 1497) PDF(533KB) ( 406) In this paper, we introduce a novel class of coplanar conics, the pencil of which can doubly contact to calibrate camera and estimate pose. We first analyze the properties of con-axes and con-eccentricity ellipses, which consist of a natural extending pattern of concentric circles. Then the general case that two ellipses have two repeated complex intersection points is presented. This degenerate configuration results in a one-parameter family of homographies which map the planar pattern to its image. Although it is unable to compute the complete homography, an indirect 3-degree polynomial or 5-degree polynomial constraint on intrinsic parameters from one image can also be used for camera calibration and pose estimation under the minimal conditions. Furthermore, this nonlinear problem can be treated as a polynomial optimization problem (POP) and the global optimization solution can be also obtained by using SparsePOP (a sparse semidefinite programming relaxation of POPs). Finally, the experiments with simulated data and real images are shown to verify the correctness and robustness of the proposed technique. References|Related Articles|Metrics

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Detecting Shifted Double JPEG Compression Tampering Utilizing Both Intra-Block and Inter-Block Correlations ZHANG Yu-jina (张玉金), LI Sheng-honga* (李生红), WANG Shi-linb (王士林) 2013, 18 (1): 7-16. doi:10.1007/s12204-013-1362-9 Abstract( 1933) PDF(983KB) ( 510) Copy-paste forgery is a very common type of forgery in JPEG images. The tampered patch has always suffered from JPEG compression twice with inconsistent block segmentation. This phenomenon in JPEG image forgeries is called the shifted double JPEG (SDJPEG) compression. Detection of SDJPEG compressed image patches can make crucial contribution to detect and locate the tampered region. However, the existing SDJPEG compression tampering detection methods cannot achieve satisfactory results especially when the tampered region is small. In this paper, an effective SDJPEG compression tampering detection method utilizing both intra-block and inter-block correlations is proposed. Statistical artifacts are left by the SDJPEG compression among the magnitudes of JPEG quantized discrete cosine transform (DCT) coefficients. Firstly, difference 2D arrays, which describe the differences between the magnitudes of neighboring JPEG quantized DCT coefficients on the intrablock and inter-block, are used to enhance the SDJPEG compression artifacts. Then, the thresholding technique is used to deal with these difference 2D arrays for reducing computational cost. After that, co-occurrence matrix is used to model these difference 2D arrays so as to take advantage of second-order statistics. All elements of these co-occurrence matrices are served as features for SDJPEG compression tampering detection. Finally, support vector machine (SVM) classifier is employed to distinguish the SDJPEG compressed image patches from the single JPEG compressed image patches using the developed feature set. Experimental results demonstrate the efficiency of the proposed method. References|Related Articles|Metrics

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Adaptive Robust Control for an Active Heave Compensation System LI Jia-wang1* (李家旺), WANG Xu-yang2 (王旭阳), GE Tong2 (葛彤) 2013, 18 (1): 17-24. doi:10.1007/s12204-013-1363-8 Abstract( 1781) PDF(417KB) ( 376) Active heave compensation systems are usually employed in offshore and deep-sea operations to reduce the adverse impact of unexpected vessel’s vertical motion on the response of underwater instruments. This paper presents a control strategy for an active heave compensation system consisting of an electro-hydraulic system driven by a double rod actuator, which is subjected to parametric uncertainties and unmeasured environmental disturbances. Adaptive observer and discontinuous projection type updating law with bounded adaption rate are presented firstly to estimate the uncertain system parameters. Then a similar estimation algorithm is designed by using a multiple delayed version of the system to enhance the performance of parameter observation. A reduced order observer is also introduced to estimate unknown wave disturbances. Using the obtained uncertainty information, the resulting control development and stability analysis are implemented based on the Lyapunov’s direct method and back-stepping technique. The proposed controller guarantees the heave compensation error convergent to a bounded neighborhood around the origin. Simulations illustrate the effectiveness of the proposed control system. References|Related Articles|Metrics

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Performance Analysis of Single Relay Selection in Cooperative Communication over Nakagami-m Fading Channels ZHU Yun1* (朱赟), LIN Ru-dan2 (林如丹), XU You-yun3,4 (徐友云)，CAI Chun-xiao3 (蔡春晓), TANG Yu-chun5 (唐玉春) 2013, 18 (1): 25-28. doi:10.1007/s12204-013-1364-7 Abstract( 1225) PDF(234KB) ( 404) We derive closed-form expressions for outage probability and symbol error rate (SER) of opportunistic relaying (OR) and selection cooperation (SC). For the amplify-and-forward relay selection scheme, comparison between two selection strategies over independent non-identically distributed Nakagami-m fading channels via analytical and simulation results is given in terms of the outage probability and SER. Simulation results show that OR performs better than SC. References|Related Articles|Metrics

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Process Passing Calculus, Revisited YIN Qiang* (尹强), LONG Huan (龙环) 2013, 18 (1): 29-36. doi:10.1007/s12204-013-1365-6 Abstract( 1578) PDF(442KB) ( 414) In the context of process calculi, higher order π calculus (Λ calculus) is prominent and popular due to its ability to transfer processes. Motivated by the attempt to study the process theory in an integrated way, we give a system study of Λ calculus with respect to the model independent framework. We show the coincidence of the context bisimulation to the absolute equality. We also build a subbisimilarity relation from Λ calculus to the π calculus. References|Related Articles|Metrics

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Direct Algorithms for Steady-State Solution of Long Slender Marine Structures WANG Sheng-wei (王盛炜), XU Xue-song* (徐雪松), LIAN Lian (连琏) 2013, 18 (1): 37-43. doi:10.1007/s12204-013-1366-5 Abstract( 1358) PDF(560KB) ( 395) The steady state solution of long slender marine structures simply indicates the steady motion response to the excitation at top of the structure. It is very crucial especially for deep towing systems to find out how the towed body and towing cable work under certain towing speed. This paper has presented a direct algorithm using Runge-Kutta method for steady-state solution of long slender cylindrical structures and compared to the time iteration calculation; the direct algorithm spends much less time than the time-iteration scheme. Therefore, the direct algorithm proposed in this paper is quite efficient in providing credible reference for marine engineering applications. References|Related Articles|Metrics

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Identification of Hydrodynamic Forces on a Flexible Pipe Near Plane Boundary Subjected to Vortex-Induced Vibrations LI Xiao-chao1,2* (李小超), WANG Yong-xue3 (王永学), WANG Guo-yu3 (王国玉)，JIANG Mei-rong3 (蒋梅荣), HE Xu4 (何旭) 2013, 18 (1): 44-53. doi:10.1007/s12204-013-1367-4 Abstract( 1286) PDF(1874KB) ( 403) Formally, use of system identification techniques to estimate the forces acting on the beam may give information on hydrodynamic forces due to vortex-induced vibrations (VIVs), but no results from such attempts for submarine pipeline spans have been reported. In this study, a pipe model with a mass ratio (mass/displaced mass) of 2.62 is tested in a current tank. The gap ratios (gap to pipe diameter ratio) at the pipe ends are 2.0, 4.0, 6.0 and 8.0. The response of the model is measured using optical fiber strain gauges. A modal approach linked to a finite element method is used to estimate the hydrodynamic forces from measurement. The hydrodynamic force at the dominant response frequency is the major concern, and the lift force and added mass coefficients are calculated. Response calculations are performed using force coefficients from the inverse force analysis and the calculated results are in accordance with the experimental data. References|Related Articles|Metrics

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symptotic Calculation of Wave Period Statistics in Non-Gaussian Mixed Sea WANG Ying-guanga,b* (王迎光), XIA Yi-qinga (夏一青) 2013, 18 (1): 54-60. doi:10.1007/s12204-013-1368-3 Abstract( 1574) PDF(388KB) ( 397) This article concerns the calculation of the wave period probability densities in non-Gaussian mixed sea states. The calculations are carried out by incorporating a second order nonlinear wave model into an asymptotic analysis method which is a novel approach to the calculation of wave period probability densities. Since all of the calculations are performed in the probability domain, the approach avoids long time-domain simulations. The accuracy and efficiency of the asymptotic analysis method for calculating the wave period probability densities are validated by comparing the results predicted using the method with those predicted by using the Monte-Carlo simulation (MCS) method. References|Related Articles|Metrics

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Fabrication and Compressive Properties of Expanded Polystyrene Foamed Concrete: Experimental Research and Modeling WU Zhen (吴震), CHEN Bing* (陈兵), LIU Ning (刘宁) 2013, 18 (1): 61-69. doi:10.1007/s12204-013-1369-2 Abstract( 1500) PDF(1687KB) ( 569) As the construction of high-rise building becomes popular, improvement and innovation are required to expand the product line of lightweight concrete. In this paper, two ways of fabricating lightweight concrete were combined to make a new kind of super lightweight concrete. Normal aggregate is replaced with expanded polystyrene (EPS) granule, while foam is introduced to facilitate fabrication process. As a result, super lightweight concrete denoted as EPS foamed concrete is fabricated, whose bulk density is less than 500 kg/m3. Compressive properties of EPS foamed concrete with bulk density 300—500 kg/m3 were investigated by stress-strain curve. It’s demonstrated that the compressive strength ranges from 0.7 to 2.5MPa, which is higher than that of similar products. Furthermore, low elastic module and high residual to ultimate strength ratio ensure its excellent deformation and energy absorption capacity. At last, numerical analysis was performed to interpret the inherent variation of elastic modulus and failure mechanism of this material. The results show that EPS foamed concrete is a kind of super lightweight, easy to fabricate material with excellent compressive property and profound utilization potential. References|Related Articles|Metrics

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Risk-Identification-Based Hybrid Method for Estimating the System Reliability of Existing Jacket Platforms Under Fire XU Ji-xiang* (许继祥), ZHAO Jin-cheng (赵金城), DUAN Hai-juan (段海娟) 2013, 18 (1): 70-75. doi:10.1007/s12204-013-1370-9 Abstract( 1382) PDF(822KB) ( 400) This paper proposes a risk-identification-based hybrid method for estimating the system reliability of steel jacket structures under fire. The proposed method starts with risk identification; according to the results of hazard identification and Dow’s fire and explosion index (F&EI) methodology, the most dangerous hazard sources are determined. In term of each equipment layout in steel jacket structures, fire load is imposed and elasto-plastic analysis is performed. According to the deformed state of steel jacket structures, the weakest failure mode of steel jacket structures is identified. In order to know the effect on ultimate bearing capacity of the offshore structural system, a series of elasto-plastic analyses are performed in which single failure element contained in the weakest failure mode is removed from the whole offshore platform structural system. Finally, the failure function of the steel jacket structure is generated and the failure probability of the steel jacket structure system is estimated under fire by genetic algorithm via MATLAB program. References|Related Articles|Metrics

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New Unified Failure Model on Evenly Distributed Reinforced Concrete Members with Box Section LUO Hua-xun* (骆华勋), LIU Xi-la (刘西拉) 2013, 18 (1): 76-83. doi:10.1007/s12204-012-1293-x Abstract( 1417) PDF(930KB) ( 398) It is urgently needed to describe the structural collapse process under extreme conditions to survive people. For reinforced concrete structures it is still a difficulty to describe the failure of reinforced concrete members under complex internal force combination, such as under axial forces, bending moment, shear forces, and torsion working together. In this paper, based on the traditional Nielsen model, a new unified failure model on reinforcement evenly distributed concrete members with box section under combined forces is introduced. The advantages of the proposed new model are to consider the dowel actions of reinforcements and reasonably to consider of the shear carrying capacity of concrete, especially when compression stress of concrete is in a high value. Finally, the theoretical results of the new model are compared with a series of experimental results of box section members. The comparison has verified that the new model is more accurate and feasible for the design and calculation of box section members. References|Related Articles|Metrics

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Power Management of Parallel Hybrid Electric Power Train LI Wen1,2* (李雯), ZHANG Cheng-ning1 (张承宁) 2013, 18 (1): 84-91. doi:10.1007/s12204-012-1337-2 Abstract( 1256) PDF(970KB) ( 422) This paper presents an integrated and detailed procedure to improve the power management feature implemented in the integrated starter-generator (ISG) parallel hybrid electric vehicle. First, the configuration of the single-shaft ISG hybrid vehicle model established in MATLAB-Simulink environment is given. The vehicle model then is validated by comparing the experimental measurements and the simulation predictions of the traditional vehicle. The baseline rule based control strategy and the optimal control strategy using the dynamic programming (DP) algorithm are introduced. Finally, a suboptimal control strategy which employs the new control rules extracted from the optimal control strategy is designed with the remarkable fuel consumption performance. Key words: parallel hybrid vehicle| rule based| dynamic programming| power management References|Related Articles|Metrics

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Experimental Study on Flow Structure of a Swirling Non-Premixed Syngas Flame GE Bing* (葛冰), ZANG Shu-sheng (臧述升), GUO Pei-qing (郭培卿) 2013, 18 (1): 92-100. doi:10.1007/s12204-012-1294-9 Abstract( 1268) PDF(4879KB) ( 401) Abstract: The development of integrated gasification combined cycle (IGCC) systems provides cost-effective and environmentally sound options for meeting the future coal-utilizing power generation needs in the world. The combustion of gasified coal fuel significantly influences overall performance of IGCC power generation. Experiments are performed to investigate the characteristics of syngas swirling flame using the particle image velocimetry (PIV) in this paper. With the increase of CO/H2 molar ratio, the distance between the nozzle and the fuel vortex in flame increases at first, and then reduces slowly; maximum of the axial mean velocity increases continuously, but the axial mean velocity peaks on the side of centerline change little. The experiment indicates that with the increase of fuel to air velocity ratio, the fuel vortex grows up at first, and then becomes thinner; the distance from the fuel vortex to the nozzle reduces at first, and then increases; inner boundary of the recirculating zone increases. Furthermore, difference between the methane swirling flow field and the syngas swirling one is analyzed in this paper. It can establish the benchmarks for the development and validation of combustion numerical simulation by the data from this experiment. References|Related Articles|Metrics

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Modeling, Identification and Simulation of DC Resistance Spot Welding Process for Aluminum Alloy 5182 GONG Liang1* (贡亮), XI Yan2 (席艳), Ma Zhe-ren1 (马喆人), LIU Cheng-liang1 (刘成良) 2013, 18 (1): 101-104. doi:10.1007/s12204-013-1371-8 Abstract( 1725) PDF(376KB) ( 401) Currently the aluminum alloy resistance spot welding (AA-RSW) has been extensively used for light weight automotive body-in-white manufacturing. However the aluminum alloys such as AA5182 have inferior weldability for forming the joint due to their high reflectiveness to heat and light. Therefore it is necessary to further develop the high performance control strategy and the set-up of a new welding schedule. The welding process identification is the essential issue where the difficulty arises from the fact that the AA-RSWis a nonlinear time-varying uncertain process which couples the thermal, electrical, mechanical and metallurgical dynamics. To understand this complicated physical phenomenon a novel dual-phase M-series pseudo-random electrical pattern is adopted to excite the AA-RSW electrical-thermal process and the thermal response is recorded according to the welding power outputs. Based on the experimental information, the transfer function of an AA-RSW electricalthermal mechanism is identified, and the optimum model order and parameters are determined. Subsequently a control-oriented DC AA-RSWmodel is established to explore the welding power control algorithm. The simulated results of the control model show agreement with the experimental data, which validates its feasibility for the corresponding welding control. References|Related Articles|Metrics

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Phase Transitions Relating to the Pozzolanic Activity of Electrolytic Manganese Residue During Calcination LIU Xiao-minga,b* (刘晓明), LI Yua,b (李宇), ZHANG Ling-lingc (张玲玲)，CANG Da-qianga,b (苍大强), ZHOU Si-xunb (周思汛) 2013, 18 (1): 105-110. doi:10.1007/s12204-013-1372-7 Abstract( 1215) PDF(1016KB) ( 375) Electrolytic manganese residue (EMR) is generated from electrolytic manganese metal (EMM) industry, and its disposal is currently a serious problem in China. The EMR were calcined in the interval 100—900℃ to enhance their pozzolanic activity and characterized by the differential thermal analysis-thermogravimetry (TGDTA), X-ray diffraction (XRD), infra-red (IR) and chemical analysis techniques with the aim to correlate phase transitions and structural features with the pozzolanic activity of calcined EMR. From the phase analysis and compressive strength results, it is found that the EMR calcined within 700—800℃ had the best pozzolanic activity due to the decomposition of poorly-crystallized CaSO4 under the reducing ambient created by the decomposition of (NH4)2SO4. The appearance of reactive CaO mainly contributes to the good pozzolanic activity of EMR calcined within 700—800℃. The crystallinity of Mn3O4 increases leading an unfavourable effect on the pozzolanic behaviour of EMR calcined at 900℃. The developed pozzolanic material containing 30% (mass fraction) EMR possesses compressive strength properties at a level similar to 42.5# normal Portland cement, in the range of 41.5—50.5MPa. Besides, leaching results show that EMR blend cement pastes have excellent effect on the solidification of heavy metals. References|Related Articles|Metrics

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Direct Electrochemical Extraction of Ti5Si3 from Ti/Si-Containing Metal Oxide Compounds in Molten CaCl2 ZOU Xing-li1 (邹星礼), LU Xiong-gang1* (鲁雄刚), XIAO Wei1 (肖玮), ZHOU Zhong-fu1,2 (周忠福), ZHONG Qing-dong1 (钟庆东), DING Wei-zhong1 (丁伟中) 2013, 18 (1): 111-117. doi:10.1007/s12204-013-1373-6 Abstract( 1626) PDF(1090KB) ( 380) Direct electrochemical extraction of Ti5Si3 from pressed cathode pellets comprising of powdered Ti/Sicontaining metal oxide compounds was investigated by using molten salt electro-deoxidation technology. Three groups of mixtures including TiO2 mixed with SiO2, Ti-bearing blast furnace slag (TBFS) mixed with TiO2, and TBFS mixed with high-titanium slag (HTS) were prepared at the same stoichiometric ratio (Ti : Si = 5 : 3) corresponding to the target composition of Ti5Si3, and used as the starting materials in this experiment, respectively. The pressed porous cylindrical pellet of the Ti/Si-containing compounds served as a cathode, and two different anode systems, i.e., the inert solid oxide oxygen-ion-conducting membrane (SOM) based anode system and graphite-based anode system were used contrastively. The electrochemical experiment was carried out at 900—1 050℃ and 3.0—4.0 V in molten CaCl2 electrolyte. The results show that the oxide components were electro-deoxidized effectively and Ti5Si3 could be directly extracted from these complex Ti/Si-containing metal oxide compounds. References|Related Articles|Metrics

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Research on the Dynamic Performance of Low-Yield-Strength Shear Panel Damper for Bridge Application ZHANG Chao-feng1,2* (张超锋), ZHANG Zhi-sheng2 (张志胜), AOKI Tetsuhiko3 (青木徹彦), ZHANG Min4 (帐目) 2013, 18 (1): 118-128. doi:10.1007/s12204-013-1374-5 Abstract( 1631) PDF(1593KB) ( 366) This study seeks to develop a scientific understanding of the effects of dynamic loading history on the low-yield-strength shear panel damper (LYSPD) mechanical properties and fatigue performance. The LYSPD model is supposed as perfect elastic-plastic without strength deterioration. By adjusting the damper strength with the above supposition in the DYMO software, the serial earthquake response waves of the LYSPD under different soil conditions are obtained firstly. Subsequently, several waves, the most prone to damage at each soil condition, are selected as dynamic loading waves to verify the LYSPD dynamic performances experimentally. The test results suggest that the dynamic loading histories have no influence on the LYSPD strength or the supposed model while they affect the fatigue performance. The applicability and accuracy of three fatigue evaluation methods, cumulative plastic shear strain, cumulative energy absorption and Miner rule, are also compared according to the test results. References|Related Articles|Metrics