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30 September 2017, Volume 22 Issue 5 Previous Issue    Next Issue

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Theoretical Analysis of Er3+-Doped Telluride Glass Fiber Amplifier for 2.700 μm Laser Amplification YIN Jinpeng1 (尹金鹏), GAO Wenyuan1* (高文元), HAO Liping1 (郝丽萍), LIU Guishan1 (刘贵山), 2017, 22 (5):  513-516.  doi: 10.1007/s12204-017-1869-6 Abstract ( 542 )   The rate equations and power evolution equations of erbium-doped telluride glass fiber amplifier for both 1.530 and 2.700 μm lasers are solved numerically, the dependences of gain spectra on fiber length, dopant concentration and pump power are analyzed, and the gain of 2.700 μm laser is calculated and compared with the experimental result from reference. The numerical analysis shows that with 8 × 1024 ion/m3 erbium ion concentration, 5 m fiber length and 600 mW pump power, the gains at 1.530 and 2.700 μm may achieve 23dB or so. With larger power pump and higher dopant concentration, a net gain of 17 dB is obtained from the Er3+-doped telluride glass fiber amplifier for 110mW input signal. This fiber amplifier is promising for both 1.530 μm signal amplification and 2.700 μm laser amplification. References | Related Articles | Metrics

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Design of Car Battery Protection Device Based on Torsion Spring ZHANG Dongming1 (张东明), ZHANG Xiaoyun1* (张晓云), YANG Zhichun1 (杨智淳), YU Junwei2 (俞俊威) 2017, 22 (5):  517-522.  doi: 10.1007/s12204-017-1870-0 Abstract ( 545 )   In recent years, electric vehicles are developing rapidly in automotive industry. When involved in accidents, if the batteries of electric cars break, it is likely to cause a short circuit and start a fire. Aimed at this issue, a car battery protection device based on torsion spring has been designed. The car battery protection device can deform in a particular pattern in a collision accident. Impact energy of the accident is absorbed by the deformation, which can significantly reduce impact force on the batteries. Meanwhile, based on the principle of maximum energy absorption, some crucial parameters of the device can be determined. Furthermore, an impact simulation conducted on ANSYS software shows that maximum safety factors can be obtained when the material of car battery protection device is carbon steel. The analysis of “safe space” in the car battery protection device shows that the device can prevent battery damage effectively in general circumstances, which means the reliability of the device has been verified. Therefore, when applied to electric vehicles, the car battery protection device, which can prevent secondary accidents, significantly improves the vehicle security in accidents. References | Related Articles | Metrics

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Calculation of Strain Amplification Matrix for Strain Invariant Failure Theory Based on Representative Volume Element Models with Periodical Boundary Condition ZHAO Jian1* (赵剑), WANG Hai1 (汪海), LU Xinying1 (吕新颖), XIE Zonghong2 (谢宗蕻) 2017, 22 (5):  523-529.  doi: 10.1007/s12204-017-1871-z Abstract ( 625 )   Strain invariant failure theory (SIFT) is a micro-mechanics-based failure theory for multi-scale failure analysis of composite materials originally proposed by Gosse and Christensen. In this paper, the approach for obtaining strain amplification matrix which is a key step for the execution of SIFT is improved by adopting representative volume element (RVE) finite element models considering periodical boundary condition, based on which more actual deformation mode is reflected. The deformation modes and strain data at the characteristic points of the centroid cell of multi-cell RVE model are analyzed and taken as a reference. It can be concluded that more reasonable deformation mode and relationship between the micro-mechanical and macro-mechanical strain states are obtained by employing the new model. Finally, numerical examples are provided to illustrate the determination of strain amplification factors within the RVEs considering periodical boundary condition at the characteristic points. References | Related Articles | Metrics

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Electronic Structures and Magneto-Transport Properties of Co-Based Heusler Alloy Based Magneto-Resistance Junctions LI Yang (李杨) 2017, 22 (5):  530-535.  doi: 10.1007/s12204-017-1872-y Abstract ( 475 )   Abstract: A direct link between band structure and the ballistic transport property of full-Heusler alloys based Co2YZ/Al/Co2YZ trilayers (Y = Sc, Ti, V, Cr, Mn and Fe; Z = Al, Si and Ge) has been studied by firstprinciples calculations. It is found that the transport efficiency is determined primarily by three factors related to band structure: the shape of the band crossing Fermi energy EF, the distance d of the two intersection points of Co2YZ and Al at EF, and the absolute maximum of the energy lying in the EF-crossing band, |Emax|. The transmission coefficient distribution patterns imply that the affected factor of magneto-resistance (MR) ratio is attributed to the band features around EF. In general, an intuitively illustrated diagram is proposed to clarify the relationship between the probability of electron transition and the current magnitude. References | Related Articles | Metrics

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Effect of Orthogonal Stiffeners on the Stability of Axially Compressed Steel Jacking Pipe ZHEN Lianga (甑亮), CHEN Jinjiana* (陈锦剑), 2017, 22 (5):  536-540.  doi: 10.1007/s12204-017-1867-8 Abstract ( 445 )   Load conditions for steel pipe-jacking are complex during the construction stage. The stability of steel jacking pipe has been an increasingly important problem as jacking forces, pipe diameters and jacking distances increase. However, there are no standards for pipe reinforcement, for prevention of buckling, or for remedying pipe that buckles when being jacked axially. Past experience suggests that stiffeners can effectively reinforce the structure. This study analyzes the effect of different stiffeners on the stability of steel jacking pipe under axial compression using finite element analysis. The results suggest that the stability of steel jacking pipe can be significantly improved by using orthogonal stiffeners, in terms of engineering costs and construction space inside the pipe. Based on current engineering practice, the application of orthogonal stiffeners is discussed. This study provides a useful reference for the design and construction of steel jacking pipe. References | Related Articles | Metrics

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Effect of Modified Supplementary Cementitious Material on Performance of Mortar and Concrete in Marine Environment PAN Chonggen1* (潘崇根), LING Mingfeng1 (林明峰), WEI Dong1 (魏冬), 2017, 22 (5):  541-548.  doi: 10.1007/s12204-017-1873-x Abstract ( 448 )   This study aims to explore the durability issues regarding chloride ion corrosion of concrete structures, and further investigates the modified supplementary cementitious material (MSCM) which acts as a significant enhancer of performance of mortar and concrete. The composition of MSCM includes mineral slag powder, fly ash and inhibitor. The microstructure, sulfate erosion resistance and electric flux of high-performance concrete are tested with MSCM, and the results show that the pore structure of concrete is improved significantly along with excellent electrochemical performance. It is observed that the substantiality of concrete after being mixed with 18% (mass fraction) MSCM is enhanced effectively. The sulfate resistance coefficient of concrete is found to be greater than 1.2, and the electric flux of concrete is less than 600C. These results have demonstrated that the MSCM possesses an excellent electrochemical performance and a wide applicative prospect in marine environment. References | Related Articles | Metrics

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Correction of Wave Surge Forces to Improve Surf-Riding/Broaching Vulnerability Criterion Check Accuracy FENG Peiyuan1* (封培元), FAN Sheming1 (范佘明), MA Ning2 (马宁) 2017, 22 (5):  549-554.  doi: 10.1007/s12204-017-1874-9 Abstract ( 514 )   Surf-riding/broaching is one of the five stability failure modes to be included into the International Maritime Organization (IMO) second generation intact stability criteria (which are risk-based stability criteria) that can ensure the safety of ships in actual seaways more effectively. This study focuses on the influence of wave surge force prediction accuracy on surf-riding/broaching vulnerability criterion check result. Firstly, it is demonstrated that the wave surge force prediction method adopted in the current vulnerability criterion check procedure is not accurate and may lead to wrong conclusions. The experimental data from captive model test and the numerical result based on 3D panel method both indicate that the diffraction effect must be considered to correctly predict the wave surge forces. Besides, sophisticated methods are not suitable for Level 2 vulnerability criterion check due to their complexity. Therefore, an empirical formula for wave surge force correction based on sample ship calculation results is proposed. The proposed empirical correction formula can effectively improve the vulnerability criterion check accuracy and thus contribute to the design and safety of the ships which are vulnerable to this stability failure mode. References | Related Articles | Metrics

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Methods for Calculating Intervals of Reconstructed Results in Traffic Accidents with Different Types of Interval Traces ZOU Tiefang1,2* (邹铁方), LI Hua1,2 (李华), LI Yuelin1,2 (李岳林),CAI Ming3 (蔡铭), XIAO Jing1,2 (肖璟) 2017, 22 (5):  555-561.  Abstract ( 382 )   In order to obtain more effective uncertainty analysis methods for analyzing uncertainty of a reconstructed result in a traffic accident with different types of interval traces, three new methods are proposed. The first method is named as sub-interval perturbed method, it is used for calculating the binary interval of the reconstructed result in an accident with binary interval traces, and it can overcome the interval extension problem well. The second method is based on interval arithmetic and the first method, it is used for calculating the ternary interval of the accident reconstruction result in an accident with ternary interval traces, and the most probable value of the reconstructed result is a number. The basic idea of the third method is the same as that of the second method, it is used for calculating the ternary interval of the accident reconstruction result in an accident with mixed interval traces, and the most probable value of the reconstructed result is an interval. All methods are demonstrated and validated by numerical cases. The results show that all methods are feasible and practical. Finally, a true vehicle-motorcycle accident is given, in which the braking distance of vehicle, and the throw distances of driver and motorcycle are all binary interval traces. The accident is reconstructed by the software PC-Crash, and the interval of impact velocity is analyzed. The interval of the velocity is [55.7, 64.3] km/h. This interval result is more objective than a single number. References | Related Articles | Metrics

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Substructuring Technique for Dynamics Analysis of Flexible Beams with Large Deformation ZHANG Jianshu (张建书), RUI Xiaoting* (芮筱亭), LIU Feifei (刘飞飞), 2017, 22 (5):  562-569.  doi: 10.1007/s12204-017-1875-8 Abstract ( 449 )   In this paper, the substructuring technique is extended for the dynamics simulation of flexible beams with large deformation. The dynamics equation of a spatial straight beam undergoing large displacement and small deformation is deduced by using the Jourdain variation principle and the model synthesis method. The longitudinal shortening effect due to the transversal deformation is taken into consideration in the dynamics equation. In this way, the geometric stiffening effect, which is also called stress stiffening effect, is accounted for in the dynamics equation. The transfer equation of the flexible beam is obtained by assembling the dynamics equation and the kinematic relationship between the two connection points of the flexible beam. Treating a flexible beam with small deformation as a substructure, one can solve the dynamics of a flexible beam with large deformation by using the substructuring technique and the transfer matrix method. The dynamics simulation of a flexible beam with large deformation is carried out by using the proposed approach and the results are verified by comparing with those obtained from Abaqus software. References | Related Articles | Metrics

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Fatigue Sensitivity Analysis of Steel Catenary Riser near Touchdown Point WANG Kunpeng1* (王坤鹏), JI Chunyan1 (嵇春艳), XUE Hongxiang2 (薛鸿祥), TANG Wenyong2 (唐文勇) 2017, 22 (5):  570-576.  doi: 10.1007/s12204-017-1876-7 Abstract ( 416 )   By transforming the platform response obtained from coupled hydrodynamic analysis to the top motions of steel catenary riser (SCR), the nonlinear dynamic analysis of the SCR is carried out in Abaqus/Aqua. In this analysis, the SCR-seabed interaction is well taken into account by introducing the seabed trench model and hysteretic seabed model. The fatigue damage of the SCR near touchdown point (TDP) is calculated using rain-flow counting methodology, and the sensitivity of the fatigue damage to the seabed and wave parameters are investigated. The results indicate that as seabed stiffness increases, the fatigue life and its sensitivity to seabed stiffness decrease. Seabed trenching may benefit the fatigue life of the SCR and the trench position should be elaborated for realistic fatigue damage prediction. Due to the induced platform response, significant wave height and spectral peak period have significant effects on the fatigue damage, thus the short-term sea state bins should be carefully selected from the wave scatter diagram. References | Related Articles | Metrics

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Control Strategy Research of a Selective Catalytic Reduction System for Heavy-Duty Application WANG Tiantian1 (王天田), LIN Feng1* (林峰), HU Jie1 (胡杰),KE Yuqiang2 (柯于强), ZHANG Yueqiu3 (张岳秋) 2017, 22 (5):  577-588.  doi: 10.1007/s12204-017-1866-9 Abstract ( 480 )   An AdBlue dosing control strategy of the selective catalytic reduction (SCR) system is developed for a heavy-duty diesel (HDD) engine. The strategy includes a raw emission prediction model, an ammonia (NH3) coverage prediction model, a transient heat hysteresis correction algorithm, an NH3 leakage control model for transient operation conditions, and a feedback controller (FBC). FBC has been developed by using mathematical manipulation to change output signal of sensor based on cross-sensitivity of nitrogen oxide (NOx) sensor to NH3. The quantification of control parameters is based on experiments and Nyquist stability criterion. FBC is enabled in most test conditions to satisfy the stability requirements. NOx conversion (DeNOx) efficiency of SCR system is 82.4% in European steady-state cycle (ESC) test and 80.3% in European transient cycle (ETC) test, while the leakage of NH3 is under 10?5 volume fraction in average. References | Related Articles | Metrics

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A New Fractal Model of Elastic, Elastoplastic and Plastic Normal Contact Stiffness for Slow Sliding Interface Considering Dynamic Friction and Strain Hardening TIAN Hongliang (田红亮), CHEN Baojia* (陈保家), HE Kongde (何孔德), DONG Yuanfa (董元发), 2017, 22 (5):  589-601.  doi: 10.1007/s12204-017-1877-6 Abstract ( 400 )   The deflection properties of elastic stage, elastoplastic stage and plastic stage of elastomer were analyzed. Taking account of the kinetic friction force in friction interface and strain hardening in slow sliding interface, the elastic, elastoplastic and plastic normal contact stiffness model for harsh surface was established, which revised the Majumdar-Bhushan fractal model and made it more perfect. In the combination of macro and micro perspective, the effects of coarse surface fractal variables, kinetic friction force in the friction interface, material characters of the friction couples on the contact status and contact property were discussed by the study of digital analysis. Results imply that the normal contact stiffness improves with the increasing real contact area and normal contact load, and reduces with the augment of kinetic friction coefficient. When the kinetic friction coefficient is smaller than 0.3, the normal contact stiffness comprises a linear decrease with the increment of kinetic friction coefficient. When the kinetic friction coefficient is bigger than 0.3, the normal contact stiffness has an exponential decrease with the increasing kinetic friction coefficient. References | Related Articles | Metrics

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Exploration on Armored Equipment Materiel Support Grid Design YANG Xueqiang (杨学强), LI Wenjun* (李文俊), HUANG Jun (黄俊), HUANG Jing (黄静) 2017, 22 (5):  602-608.  doi: 10.1007/s12204-017-1850-4 Abstract ( 450 )   The core of grid technology is just to solve the problem of resource share and to eliminate information island and resource island. Thus, it is a perfect approach to apply the grid technology to armored equipment materiel support. Firstly, the military and function demands of armored equipment materiel support grid are analyzed. Besides, according to the function demand, the system structure of armored equipment materiel support grid is designed. Finally, the organizational structure of armored equipment materiel support grid is established in this paper based on actual armored equipment materiel support. References | Related Articles | Metrics

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Poisson Noise Removal Based on Nonlocal Total Variation with Euler’s Elastica Pre-processing LIU Hongyia* (刘红毅), ZHANG Zhengronga (张峥嵘), XIAO Liangb (肖亮), WEI Zhihuib (韦志辉) 2017, 22 (5):  609-614.  doi: 10.1007/s12204-017-1878-5 Abstract ( 492 )   An enhancement-based Poisson denoising method for photon-limited images is presented. The noisy image is firstly pre-processed for enhancing incomplete object information, and then it is denoised while preserving the restored structural details. A variational regularization model based on Euler’s elastica (EE) is proposed for image enhancement pre-processing. A nonlocal total variation (NLTV) regularization model is then employed in the second stage of image denoising. The above two optimization problems are solved by the alternating direction method of multipliers (ADMM). For Poissonian images with low image peak values, experiments demonstrate the validity and efficiency of the proposed method for both restoring geometric structure and removing noise. References | Related Articles | Metrics

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Range Profile Target Recognition Using Sparse Representation Based on Feature Space L ¨U Wentao1* (吕文涛), WANG Junfeng2 (王军锋), YU Wenxian2 (郁文贤), BAO Xiaomin1 (包晓敏) 2017, 22 (5):  615-623.  doi: 10.1007/s12204-017-1879-4 Abstract ( 446 )   A novel method is presented to improve the recognition rate of warhead in this paper. Firstly, a tool for electromagnetic calculation, like CST Microwave Studio, is used to simulate the frequency response of the electromagnetic scattering. Secondly, the echo and further the range profile are acquired from the frequency response by further processing. Thirdly, a set of discriminative features is extracted from the range profiles of the target. Fourthly, these features are used to construct a dictionary for the sparse representation classifier. Finally, the sample of the target can be classified by solving the sparsest coefficients. Since the reconstruction result is determined by a linear combination of the training samples, this method has a good robustness for the variable features. By formulating the problem within a feature-based sparse representation framework, the presented method combines the discriminative features of each sample during the sparse recovery process rather than in a postprocessing manner. Moreover, based on the feature representation space rather than a single feature or image pixel, the constructed dictionary exhibits both strong expressive and discriminative powers that can enhance the classification performance of the test sample. A series of test results based on the simulated data demonstrates the effectiveness of our method. References | Related Articles | Metrics

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Target Priority Determination Methods by Interval-Valued Intuitionistic Fuzzy Sets with Unknown Attribute Weights XU Gongguo1* (徐公国), DUAN Xiusheng1 (段修生), LU Hao2 (吕豪) 2017, 22 (5):  624-632.  doi: 10.1007/s12204-017-1880-y Abstract ( 508 )   The paper aims at the problem of multi-targets threat degree being hard to be evaluated accurately in complex air defense battlefield environments. Combined with multi-sensors information fusion and interval-valued intuitionistic fuzzy sets (IVIFS) theories, the target priority determination is studied. The score and accuracy functions of IVIFS are improved with thinking about the hesitating information in order to increase the rationality. Then, the influence factors of target priority and the nonlinear relationship between the influence factors and target priority are analyzed. Next, the algorithms for calculating the factor weights and sensor weights are given. Based on the theory of IVIFS and technique for order preference by similarity to an ideal solution (TOPSIS), two methods of target priority determination based on the IVIFS and TOPSIS are proposed. At last, an application example verifies the effectiveness and flexibility of the proposed algorithms. References | Related Articles | Metrics

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A Real-Time Collision-Free Path Planning of a Rust Removal Robot Using an Improved Neural Network SUN Ling (孙玲) 2017, 22 (5):  633-640.  doi: 10.1007/s12204-017-1881-x Abstract ( 507 )   In this paper, a real-time collision-free path planning of the rust removal robot in a ship environment is proposed, which is based on an improved biologically inspired neural network algorithm. This improved algorithm is based on the biologically inspired neural network and modified with obstacle detection sensors and kinematic state templates, and is implemented in a ship rust removal robot planning system for dynamic trajectory generation. The real-time optimal trajectory is generated by the biologically inspired neural network, and the moving obstacle detection process of a ship robot working on the wall is simulated with the obstacle detection sensors models. The local real-time trajectory can be re-planned by the updated local map information, where the obstacle detection sensors are used to inspect partial environment information and update the robot nearby information in real time in the original neural network algorithm. At the same time, the method of the kinematic state templates matching and searching is used to solve the pipes’ influence of the rust removal robot climbing on the wall, which can not only provide a smooth path, but also can judge the motion direction and turning angle of the robot. Comparison of the proposed approach with the simulation shows that the improved algorithm is capable of planning a real-time collision-free path with achieving the local environmental information and judging the rust removal robot’s motion direction and turning angle. This proposed algorithm can be good used in the ship rust removal robot. References | Related Articles | Metrics