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    29 August 2015, Volume 20 Issue 4 Previous Issue    Next Issue

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    Sensitivity Analysis of Wave Slamming Load with Respect to Wind Load for Semi-Submersible Platform Design
    HUO Fa-li1,2* (霍发力), ZHANG Hui-xin1 (张会新), SUO Jian2 (索 健),YANG De-qing1 (杨德庆), CUI Jin2 (崔 锦)
    2015, 20 (4):  385-394.  doi: 10.1007/s12204-015-1619-6
    Abstract ( 683 )  
    A design of offshore floating structure is mainly based on the extreme response analysis due to the forces experienced. The extreme response can induce the negative air gap response and potential impact to the deck bottom of floating structure. It is important to predict the slamming load in order to check the strength of local structures which withstand the wave slamming. In recent years, studies of the effects of wind load on air gap response and slamming load are ignored. When the platform suffers the extreme wave, the wind is also harsh. Moreover, the wind load can affect the motion response of the platform. The wind load cannot be simulated easily by model test in towing tank whereas it can be simulated accurately in wind tunnel test. Though the model test results are not accurate enough for air gap and slamming load evaluation due to the loss of wind effect, they can be used as a good basis for tuning the radiation damping and viscous drag in numerical simulation. This paper aims at presenting the sensitivity analysis results of wave slamming load with respect to the wind load for the design of semi-submersible platform. As an example of semi-submersible drilling platform design, the wind tunnel test has been carried out, and the sea-keeping model test is also performed in towing tank, while the wind load effect is ignored. According to the model test results, a numerical model is tuned and validated by ANSYS AQWA. Sensitivity analysis studies of the relative velocity between water particle and platform surface and the wave slamming load with respect to the wind load are performed in time domain by the tuned numerical model. Five simulation cases about the presented platform are simulated based on the results of wind tunnel tests and sea-keeping tests. The sensitivity analysis results are valuable for the floating platform design.
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    Analysis on Deepwater Mooring System of Sandglass-Type FDPSO
    YAO Yu-xin (姚宇鑫), WANG Wen-hua (王文华), HUANG Yi* (黄 一), YE Mao-sheng (叶茂生)
    2015, 20 (4):  395-402.  doi: 10.1007/s12204-015-1578-y
    Abstract ( 535 )  
    In order to solve the performance limitations of traditional ship-type and cylindrical FDPSO (floating drilling production, storage and offloading unit), we present a new FDPSO with a sandglass-type floating body. Based on the hydrodynamic performance of the newly developed floating model, a suitable analysis method for its deepwater mooring system has been proposed. Furthermore, by studying the effects of different mooring parameters on the motion performance of FDPSO, we achieve some useful conclusions and principles to design the mooring scheme in deep sea which has been validated to satisfy the Det Norshke Veritas (DNV) requirements. The study of this paper is expected to provide a reasonable and feasible reference and design solution for the deep sea positions of the new sandglass-type FDPSO.
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    Relay Selection and Power Allocation in Amplify-and-Forward Cognitive Radio Networks: A Special Spectrum Sharing Scheme
    ZHAO Da-qian* (赵大骞), PEI Er-rong (裴二荣), ZHANG Zhi-zhong (张治中)
    2015, 20 (4):  403-407.  doi: 10.1007/s12204-015-1642-7
    Abstract ( 504 )  
    In this paper, we present a special spectrum sharing scheme that is a joint optimization of relay selection and power allocation at the secondary transmitter, where the primary user is incapable of supporting its target signal-to-noise ratio (SNR). Specifically, the selected secondary transmitter assists the primary user with achieving its target SNR via two-phase cooperative amplify-and-forward relaying. By searching for the candidate secondary transmitters which have already satisfied the primary user’s target SNR, we can select the optimal secondary transmitter. This optimal secondary transmitter not only satisfies the primary user’s target SNR, but also maximizes the throughput of the secondary user. We study this joint optimization problem such that the secondary user’s throughput is maximized under the constraint that satisfies the primary user’s target SNR. Numerical results show that our scheme can maximize the throughput of the secondary user, and can obtain the win-win solution for the primary and secondary systems.
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    Simulation of Adaptive Control Strategy for Electrical Discharge Machining Process
    YANG Qing-zhao (杨青照), ZHOU Ming* (周明), TIAN Hong-sen (田洪森),ZHANG Hui-sheng (张惠生), XU Dong-hui(许东晖)
    2015, 20 (4):  408-414.  doi: 10.1007/s12204-014-1577-4
    Abstract ( 447 )  
    Electrode down-time is an important factor affecting the efficiency and stability of electrical discharge machining (EDM) process. In the research, a way of simulating the regulation of the electrode down-time in an EDM adaptive control system has been studied. All the simulations are performed on Matlab. The simulation results demonstrate that this adaptive controller by regulating electrode down-time can direct the gap state to follow the specified reference gap state with or without disturbances. Finally, the adaptive control scheme is also validated by experiments. The significance of the simulation of an EDM adaptive control system lies on the fact that it provides a convenient way to guide the actual production and provides a new study method for the research of EDM control strategy with no regard of experimental conditions.
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    Precision Improvement of the Discrete Calculation Method for Sound Radiation Research
    LUO Zhi (罗智), HAO Zhi-yong* (郝志勇), ZHENG Xu (郑 旭)
    2015, 20 (4):  415-419.  doi: 10.1007/s12204-015-1616-9
    Abstract ( 487 )  
    Sound radiation of thin plates is a common problem in engineering. Hashimoto proposed the discrete calculation method (DCM) to deal with the problem. The calculation of the radiation impedance of the rectangular element is more cumbersome than that of the circular one, so the discrete rectangular radiation element is approximated by the circular one. However, error is also introduced. The formula developed by Sha has been employed to get self- and mutual-radiation impedances of rectangular radiation element. Numerical study was performed to verify error introduced by the approximation Hashimoto adopted. Experimental researches on sound radiation of a 2mm-thick and a 4mm-thick magnesium alloy plates were also carried out to evaluate the errors introduced by the approximation. The experimental results indicate that the circular approximation Hashimoto adopted overestimates the sound radiation efficiency. The maximum error levels of the radiation efficiencies of the 2mm-thick and 4mm-thick magnesium alloy plates are up to 0.15 and 0.12, respectively. The effect of element aspect ratio on the sound radiation efficiency is also remarkable.
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    Coast-Down Modeling of Canned Motor Based on Torque Behavior Study
    XUE Ya-bo (薛亚波), YAO Zhen-qiang1,2* (姚振强), CHENG De1 (成 德), SHEN Hong1,2 (沈 洪), LI Meng-chao3 (李孟超)
    2015, 20 (4):  420-426.  doi: 10.1007/s12204-015-1643-6
    Abstract ( 544 )  
    The coast-down behavior is specially designed to satisfy the certain flow requirements in a special kind of canned motor pump when it is used in primary reactor coolant system. However, coast-down models once used are not suitable for designing ultra-large canned motor pumps with flywheels, in which case rotor’s fluid resistance of canned motor is modeled by an empirical constant. When the size of canned motor increases, the error of empirical relationship becomes remarkable. In thrall to material’s density and strength, flow resistance of coast-down behavior should be dynamically modeled accurately to reduce the demands of materials. In this paper, an improved analytical model is proposed to study barbell-like canned motor’s coast-down characteristic based on basic torque behavior researches in Taylor-Couette flow and hydraulic coupler, where bearing’s resistance is ignored. This model takes geometric and kinematic parameters into consideration. In addition, the influence of pressure and temperature is coupled into this coast-down model by using Reolands’ viscosity relationship. Based on this model, coast-down behavior is studied and parameters sensitivity analysis is conducted from design view point. Parameters sensitivity analysis indicates that the density and distribution of materials have more remarkable influence on coast-down behavior compared with working condition and geometric parameters.
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    Dynamic Fault Diagnosis Using the Improved Linear Evidence Updating Strategy
    SHANG Qun-li1 (尚群立), ZHANG Zhen2 (张 镇), XU Xiao-bin2* (徐晓滨)
    2015, 20 (4):  427-436.  doi: 10.1007/s12204-015-1644-5
    Abstract ( 419 )  
    The majority of the existing fault diagnosis methods using Dempster-Shafer (DS) evidence theory (DST) all provide the “static” fused results by combining several pieces of diagnosis evidence, which only reflect the current running status of monitored equipment. This paper presents the dynamic diagnosis strategy by using recursively the improved linear evidence updating rule. Its updated result can synthesize the diagnosis evidence collected at historical, current and future time steps by dynamically adjusting the proposed smoothing linear combination weights. The diagnosis examples of machine rotor show that the proposed method can provide more reliable and accurate results than the diagnosis methods based on the classical updating strategies.
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    Large Thinned Array Design Based on Multi-objective Cross Entropy Algorithm
    BIAN Li1* (边 莉), BIAN Chen-yuan1 (边晨源), WANG Shu-min2 (王书民)
    2015, 20 (4):  437-442.  doi: 10.1007/s12204-015-1645-4
    Abstract ( 479 )  
    To consider multi-objective optimization problem with the number of feed array elements and sidelobe level of large antenna array, multi-objective cross entropy (CE) algorithm is proposed by combining fuzzy c-mean clustering algorithm with traditional cross entropy algorithm, and specific program flow of the algorithm is given. Using the algorithm, large thinned array (200 elements) given sidelobe level (?10, ?19 and ?30 dB) problem is solved successfully. Compared with the traditional statistical algorithms, the optimization results of the algorithm validate that the number of feed array elements reduces by 51%, 11% and 6% respectively. In addition, compared with the particle swarm optimization (PSO) algorithm, the number of feed array elements from the algorithm is more similar, but the algorithm is more efficient.
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    Influence of the Unit Y-Shaped Microchannel Geometry on the Capillary Flow
    LIU Wang-yu* (刘旺玉), CHEN Wei (陈 伟), PENG Yi (彭 毅), LUO Yuan-qiang (罗远强)
    2015, 20 (4):  443-448.  doi: 10.1007/s12204-015-1646-3
    Abstract ( 471 )  
    Fractal networks are widely applied in the field of heat and mass transfer. As one of the important parts of the fractal network, Y-shaped structure definitely has a significant impact on the performance of the whole network. In this paper, the analytical relationship between Y-shaped microchannel geometry and its capillary flow time is established through theoretical analysis with mass continuity equation and Navier-Stokes (N-S) equations. The result reveals that the capillary flow time increases with the increase of the topology length and bifurcation angle of the Y-shaped microchannel, but decreases with the increase of the channel width.
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    Residual Life Prediction Based on Nonlinear Fatigue Damage Accumulation Model
    GAO Hui-ying (高会英), ZUO Fang-jun (左芳君), LU Zhi-qiang (吕志强),ZHU Shun-peng (朱顺鹏), HUANG Hong-zhong* (黄洪钟)
    2015, 20 (4):  449-453.  doi: 10.1007/s12204-015-1647-2
    Abstract ( 531 )  
    When a nonlinear fatigue damage accumulation model based on damage curve approach is used to get better residual life prediction results, it is necessary to solve the problem caused by the uncertain exponent of the model. Considering the effects of load interaction, the assumption that there is a linear dependence between the exponent ratio and the loading ratio is established to predict fatigue residual life of materials. Three experimental data sets are used to validate the rightness of the proposition. The comparisons of experimental data and predictions show that the predictions based on the proposed proposition are in good accordance with the experimental results as long as the parameters that represent the linear correlativity are set an appropriate value. Meanwhile, the accuracy of the proposition is approximated to that of an existing model. Therefore, the proposition proposed in this paper is reasonable for residual life prediction.
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    Estimation of Reliability Derived from Binomial Distribution in Zero-Failure Data
    HAN Ming (韩明)
    2015, 20 (4):  454-457.  doi: 10.1007/s12204-015-1648-1
    Abstract ( 592 )  
    This paper introduces a new method, E-Bayesian estimation method, to estimate the reliability in zero-failure data. The definition of E-Bayesian estimation of the reliability is given. Based on the definition, the formulas of E-Bayesian estimation and hierarchical Bayesian estimation of the reliability are provided, and property of the E-Bayesian estimation, i.e. relation between E-Bayesian estimation and hierarchical Bayesian estimation, is discussed. Calculations performed on practical problems show that the proposed new method is feasible and easy to operate.
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    Quantify Measuring Method for Combat Unit Mission Focusing on Unsuccess Prevention
    LI Dan (李 丹), FENG Qiang* (冯 强), WANG Zi-li (王自力), REN Yi (任 羿)
    2015, 20 (4):  458-463.  doi: 10.1007/s12204-015-1649-0
    Abstract ( 415 )  
    To describe the self-adaptive character of combat unit (CU), which may not be able to give precise explanation by conventional mission measurement, we present a measurement method orienting to unsuccess prevention for CU mission. Firstly, the task characteristics of multi-phase and multi-level of CU are explained. On this basis, a hierarchical measuring system including measure of capability deviation, relating to basic task unsuccess and composite task is given by quantifying the disturbance. Based on unified measurement, the basic task unsuccess according to presumable domain from required domain is quantified, and the composite task unsuccess is also quantified. Finally, a case of capability deviation measurement and its impact on overall unsuccess are presented for check.
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    Risk Assessment of Contractor Support Based on Improved Risk Matrix Method
    ZHANG Fu-yuan* (张福元), LI Dong-yang (李东阳), GENG Bin (耿 斌), LIU Zhan-ling (刘占岭)
    2015, 20 (4):  464-467.  doi: 10.1007/s12204-015-1650-7
    Abstract ( 636 )  
    For the current situation that the application of risk matrix method may result in too many risk ties which will block risk management and decision making, and based on the brief introduction of risk matrix method, this paper subdivides the risk levels, gives an improved risk matrix method, conducts risk assessment of contractor support using the improved risk matrix method, and determines the risk rates and the acceptable level.
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    Effect of Nose Shape on Semi-Armor-Piercing Warhead Penetration Performance
    SHI Quan (石 全), XIONG Fei* (熊 飞), LIU Feng (刘 锋), CHEN Cai (陈 材)
    2015, 20 (4):  468-471.  doi: 10.1007/s12204-015-1651-6
    Abstract ( 590 )  
    The numerical simulations of different head shape semi-armor-piercing warheads penetrating thin steel target are done using the finite element software ANSYS/LS-DYNA, and the whole process of different nose shape semi-armor-piercing warheads vertically penetrating the thin steel plate is compared. Besides, the influence of impact angle on penetration performance of three different nose shape projectiles is researched. The analysis results indicate that the nose shape has a significant influence on semi-armor-piercing warhead penetration performance. The effect of impact angle on the three kinds of projectiles’ residual kinetic energy and deflection is different. The research results provide references for designing of warhead and battlefield damage assessment.
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    A Novel Model of Failure Rate Prediction for Circular Electrical Connectors
    SUN Bo1* (孙 博), YE Tian-yuan1 (叶田园), FANG Yuan2 (方 园)
    2015, 20 (4):  472-476.  doi: 10.1007/s12204-015-1652-5
    Abstract ( 467 )  
    The reliability of electrical connectors has critical impact on electronic systems. It is usually characterized by failure rate prediction value according to standard MIL-HDBK-217 (or GJB-299C in Chinese) in engineering practice. Given to their limitations and mislead results, a new failure rate prediction models needs to be presented. The presented model aims at the mechanism of increase of film thickness which leads to the increase of contact resistance. The estimated failure rate value can be given at different environmental conditions, and some of the factors affecting the reliability are taken into account. Accelerated degradation test (ADT) was conducted on GJB599III series electrical connector. The failure rate prediction model can be simply formed and convenient to calculate the expression of failure rate changing with time at various temperature and vibration conditions. This model gives an objective assessment in short time, which makes it convenient to be applied to the engineering.
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    Simulation on Reliability Enhancement Testing Technology of Ramming System
    HU Hui-bin1,2* (胡慧斌), CAO Li-jun1 (曹立军), CHEN Shu-xiao2 (陈树肖), MA Ji-sheng1 (马吉胜)
    2015, 20 (4):  477-481.  doi: 10.1007/s12204-015-1653-4
    Abstract ( 446 )  
    Ramming system is the key device to guarantee the firing speed of self-propelled gun. Based on traditional reliability enhancement testing method, a new kind of reliability enhancement testing simulation method of ramming system is put forward firstly. In CAD software Pro/E and dynamic simulation software ADAMS, the virtual prototype of ramming system is established. In EASY5 software, the corresponding hydraulic system and control system models are built. The reliability enhancement testing virtual environment of ramming system is developed using the mechanical-electrical-hydraulic co-simulation technology. Based on the load spectra provided by virtual prototype, and the stress distribution provided by finite element analysis and material’s S-N curve (S is fatigue strength, N is fatigue life), a model of fatigue enhancement coefficient is established through the failure mechanism analysis. The simulation processes and simulation results show the feasibility of reliability enhancement testing based on virtual prototype, and provide sufficient theory reference for structure improvement and optimization of ramming system.
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    Binary Logic State Transition Oriented Formal General Reliability Model
    ZHOU Yi-zhou (周一舟), REN Yi (任 羿), LIU Lin-lin* (刘林林),MA Zheng (马 政), WANG Zi-li (王自力)
    2015, 20 (4):  482-488.  doi: 10.1007/s12204-015-1654-3
    Abstract ( 643 )  
    There were various conventional modeling techniques with varied semantics for system reliability assessment, such as fault trees (FT), Markov process (MP), and Petri nets. However, it is strenuous to construct and to maintain models utilizing these formalisms throughout the life cycle of system under development. This paper proposes a unified formal modeling language to build a general reliability model. The method eliminates the gap between the actual system and reliability model and shows details of the system clearly. Furthermore, the model could be transformed into FT and MP through specific rules defined by a formal language to assess system-level reliability.
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    Data-Driven Process Monitoring and Fault Tolerant Control in Wind Energy Conversion System with Hydraulic Pitch System
    WANG Kai1,2 (王 凯), LUO Hao1* (罗 浩), KRUEGER M1,DING S X1, YANG Xu3* (杨 旭), JEDSADA S4
    2015, 20 (4):  489-494.  doi: 10.1007/s12204-015-1655-2
    Abstract ( 521 )  
    Wind energy is one of the widely applied renewable energies in the world. Wind turbine as the main wind energy converter at present has very complex technical system containing a huge number of components, actuators and sensors. However, despite of the hardware redundancy, sensor faults have often affected the wind turbine normal operation and thus caused energy generation loss. In this paper, aiming at the wind turbine hydraulic pitch system, data-driven design of process monitoring (PM) and diagnosis has been realized in the wind turbine benchmark. Fault tolerant control (FTC) strategies focused on sensor faults have also been presented here, where with the implementation of soft sensor the sensor fault can be handled and the performance of the system is improved. The performance of this method is demonstrated with the wind turbine benchmark provided by MathWorks.
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    An Interval Algorithm of Maintenance Windows Under Uncertain Parameters
    WEN Liang1,2* (温 亮), WU Su1 (吴 甦), JIA Xi-sheng2 (贾希胜)
    2015, 20 (4):  495-499.  doi: 10.1007/s12204-015-1656-1
    Abstract ( 472 )  
    For improving the method of finding maintenance windows under uncertain parameters, an algorithm of maintenance window under uncertainties is presented using interval analysis and sensitivity analysis. Age replacement model is selected to demonstrate how to use this new algorithm. Considered the uncertainties, the optimal maintenance interval of preventive maintenance is not only a single value, but a possible range. The requirement from maintenance engineers is also considered, the maintenance window is made as a symmetrical interval format, like (100 ± 10) day. Comparing with the methods using in the literatures, the new algorithm is without requirement of distribution assumption of uncertain parameter values and computer simulation.
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    Reliability Analysis for the Competing Failure with Probabilistic Failure Threshold Value and Its Application to the k-out-of-n Systems
    YUAN Rong1,2 (袁 容), LI Hai-qing2* (李海庆), HE Li-ping2 (何俐萍), GAO Hui-ying2 (高会英)
    2015, 20 (4):  500-507.  doi: 10.1007/s12204-015-1657-0
    Abstract ( 581 )  
    A method for reliability analysis of the competing failure with the probabilistic failure threshold value not the fixed threshold value is presented, which involves the random shocks and the degradation is independent and dependent respectively. Specifically, for the dependent condition, the effect due to the random shocks on the degradation is considered with a damage factor. In addition, the dependent competing failure model is applied to the reliability analysis of the k-out-of-n systems. Finally, two studied cases are presented to illustrate the proposed method, and the results show the proposed method is reasonable.
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    Systematic Safety Analysis Method for Power Generating Equipment
    ZHANG Wei1* (张 伟), HOU Yue-min1,2 (侯悦民)
    2015, 20 (4):  508-512.  doi: 10.1007/s12204-015-1658-z
    Abstract ( 402 )  
    A systematic safety analysis method is presented to guide the whole analysis process starting with safety analysis requirement and ending with technical and economical evaluation of the knowledge model and the arrangement of sensors. The method consists of five phases, including data acquisition on factual evidence and collecting design, manufacturing, and installation data of equipment; establishing knowledge model; measurable analysis and selection of sensors as well cost evaluation; knowledge description; and overall evaluation. The proposed method is used for safety analysis of hydraulic power generating units and the analysis results validate the method very well.
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