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03 August 2017, Volume 22 Issue 4 Previous Issue    Next Issue

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Investigation of Springback Behavior and Process Control for Stamping of Ring-Shaped Workpiece HE Junyi (何俊艺), WANG He (王贺), PENG Linfa (彭林法),YI Peiyun* (易培云), LAI Xinmin (来新民), LIN Zhongqin (林忠钦) 2017, 22 (4):  385-394.  doi: 10.1007/s12204-017-1851-3 Abstract ( 486 )   Abstract: Due to the elastic deformation of metal stamping, springback is a serious problem to cause shape deviation and thus reduce precision. The springback behavior of ring-shaped workpiece is investigated in this paper and an auxiliary boss device is proposed to control the springback deformation. A finite element model is developed. The characteristic parameters including boss height, boss angle and boss gap are discussed systematically. It can be concluded that the gap has a positive linear correlation with springback percentage, and the boss angle has an optimal interval of 30°—60° to reduce springback. When the boss height increases, the springback decreases, but the effect weakens when the boss height is larger than 1.0 mm. Then, a response surface analysis is conducted with Design Expert 8.0.5 software and an optimal parameter process window (i.e., boss height from 2.1 to 3.0 mm, boss angle from 53°to 60°and the gap from 0 to 1.2 mm) is obtained. Finally, a set of molds are fabricated and the stamping experiments are conducted. The springback behavior is well controlled. The springback percentage can be decreased from 33% to 6% by using the auxiliary boss device of ring-shaped workpiece. References | Related Articles | Metrics

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Effect of Carbon Nanotube Concentration on Cooling Behaviors of Oil-Based Nanofluids During the Immersion Quenching CHEN Si* (陈斯), ZENG Xiaoshu (曾效舒), YUAN Qiuhong (袁秋红) 2017, 22 (4):  395-401.  doi: 10.1007/s12204-017-1852-2 Abstract ( 461 )   Abstract: Oil-based nanofluids including 0.75%—1.75% (mass fraction) carbon nanotubes (CNTs) without any surfactants have been synthesized by a two-step process. The probes machined from 45# steel with 22mm diameter and 50mm length are quenched in the as-synthesized CNT nanofluids for testing the cooling behaviors of the nanofluids. The laser diffraction particle size analyzer, scanning electronic microscope (SEM), X-ray diffractometer and transmission electron microscope (TEM) are used to characterize the quality and distribution of CNTs in the nanofluids. The wettability and viscosity of 30# oil and oil-based CNT nanofluids are measured by a goniometer at 15 °C and a rotational type viscometer at 40 °C, respectively. The results show that the cooling efficiency of the oil-based CNT nanofluids is better than that of 30# oil. Moreover, the cooling rate of the naonofluids increases with the further increase of the CNT concentration. When the mass fraction of CNTs increases to 1.75%, the cooling rate of the naonofluids reaches a maximum at 760 °C and it is increased by 77.8% as compared to that of base oil. The improved cooling rate of oil by CNTs is mainly due to the uniform distribution and excellent thermal conductivity of CNTs. References | Related Articles | Metrics

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Gain and Emission Spectrum Characteristics of 465 nm Laser Diode Pumped Tm3+-Doped Telluride Glass Fibers ABDALLA Saadelnour, JIANG Chun* (姜淳) 2017, 22 (4):  402-405.  doi: 10.1007/s12204-017-1853-1 Abstract ( 445 )   Abstract: Gain and emission spectrum characteristics of Tm3+-doped telluride glass fibers pumped with 465 nm lasers are analyzed. The rate and power propagation equation groups of the fibers are solved numerically and the effects of the fiber parameters including active ion concentration, length and pump power on the gain spectra and amplified spontaneous emission (ASE) spectra are analyzed. The results show that with a pump parameter of 465 nm/200 mW, a doping concentration of 2.5×1025 ion/m3 and a fiber length of 16 m, the gain and ASE spectra can cover from 1.100 to 1.900 μm, and the gain and ASE power peaks can reach 52 dB and 8 mW, respectively. References | Related Articles | Metrics

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Gain and Noise Figure Analysis of Er3+-Doped YAG Transparent Ceramic Microchip Amplifier YIN Jinpeng (尹金鹏), GAO Wenyuan* (高文元), LIU Guishan (刘贵山),HAO Hongshun (郝洪顺), YAN Shuang (闫爽), JIANG Chun* (姜淳) 2017, 22 (4):  406-410.  doi: 10.1007/s12204-017-1854-0 Abstract ( 471 )   Abstract: The rate equations and the power evolution equations based on excited state absorption (ESA) and cooperative upconversion (CUC) of high concentration erbium-doped yttrium aluminum garnet (YAG) transparent ceramic waveguide amplifier are set up to analyze the effects of the pump power, active ion concentration and waveguide length on the amplifier gain and noise figure (NF). The numerical analysis predicts that with a pump power of 100 mW, an active ion concentration of 1.0×1026 ion/m3 and a waveguide length of 3 cm, a small-signal gain of 30 dB and an NF of 5 dB can be achieved in the micro-chip amplifier. References | Related Articles | Metrics

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Absolute Quantum Efficiency Calibration of Analog Detectors with Twin Photon Current GAO Dongyang1,2 (高冬阳), XIA Maopeng1 (夏茂鹏), LI Jianjun1 (李健军),HU Youbo1 (胡友勃), ZHENG Xiaobing1,2* (郑小兵) 2017, 22 (4):  411-416.  doi: 10.1007/s12204-017-1855-z Abstract ( 380 )   Abstract: Correlated photon is exploited as a tool for absolute quantum efficiency calibration of photon detectors working in the photon-counting regime. We extend the method from photon-counting regime to the absolute calibration of analog regime photon detectors. A revised calibration module is proposed based on balance detection and fluctuation restrictions conditions applied to analog photon detectors. An absolute calibration experimental system is established. This method shows a relative standard uncertainty of 2.1% and a relative deviation of 1% compared with those of the typical photomultiplier quantum efficiency. References | Related Articles | Metrics

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Numerical Analysis of the Soil Compaction Degree Under Multi-Location Tamping WANG Wei1,2 (王威), DOU Jinzhong2 (窦锦钟), CHEN Jinjian2 (陈锦剑), WANG Jianhua2* (王建华) 2017, 22 (4):  417-433.  doi: 10.1007/s12204-017-1856-y Abstract ( 453 )   Abstract: Dynamic compaction (DC) is an efficient soil improvement technique. The previous numerical studies mainly focus on the soil response of single location tamping, but ignore the soil compaction degree under multilocation tamping. In this study, a numerical investigation of multi-location tamping in granular soils is carried out using three-dimensional (3D) finite element model (FEM). The behaviors of the granular soils are described by means of the viscoplastic cap model. The constitutive relationship of the soils is implemented into LS-DYNA and is integrated with 3D FEM for numerical investigation. Then utilizing the field data from the previous studies, we investigate the soil compaction degree at different stages by a case of two basic patterns, and discuss the cause of soil response. Lastly, we evaluate the effect of construction parameters on soil compaction. The simulation results show that the previous tamping affects the soil compaction degree beneath the adjacent tamping location, and the effect is greater near the side of previous location. Meanwhile, the soil compaction degree around the existing tamping crater weakens due to the adjacent tamping. Moreover, the rational selection of DC construction parameters can improve the soil compaction degree, and some hints on the effect of soil compaction are given. References | Related Articles | Metrics

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Investigation on Maneuverability of a Twin-Screw Ship Driven by One Screw LIU Xiaojian* (刘小健), FAN Sheming (范佘民) 2017, 22 (4):  434-439.  doi: 10.1007/s12204-017-1857-x Abstract ( 500 )   Abstract: It is possible for a twin-screw ship that one screw failure occurs during navigation, and the maneuverability in this case should be noticed by ship designers and operators. It is of great significance to evaluate the related risk. Firstly, a mathematical model for the twin-screw ship maneuvering motion with one failed screw is developed based on the maneuvering model group (MMG) equations, and verified by the model test results. Secondly, the maneuvering motions of a twin-screw liquefied natural gas (LNG) ship with one free rotating failure screw or with one locked failure screw are simulated and compared by using the mathematical model. It is shown that the numerical modeling results are in agreement with the model test results. Compared with those of normal navigation, the port turning ability of the ship with one failed port screw is better, but the starboard turning ability and yaw checking ability become worse. The maneuverability of the ship with locked failure screw is better than that with free failure screw, although the ship speed drops obviously. References | Related Articles | Metrics

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Warship Spare Parts Configuration Optimization for Stock Control: Investigating the Gap Between Qualitative and Quantitative Constraints JIN Jiashan (金家善), CAI Zhiming* (蔡芝明), CHEN Yanqiao (陈砚桥) 2017, 22 (4):  440-448.  doi: 10.1007/s12204-017-1858-9 Abstract ( 458 )   Abstract: This paper investigates the gap between qualitative and quantitative constraints in spare parts stock control, with specific reference to warship spare parts support projects. A critical literature review of theoretical contributions about qualitative or quantitative factors for warship spare parts warehouse management is firstly provided, which allows to analyze the reasons for this qualitative-quantitative gap by addressing the limitations of spare parts models developed in the literature. Therefore a model including cloud model, marginal analysis and Lagrange multiplier method (CML) for study is proposed in this paper to bridge the gap. The model is used to solve the mix-constraints (both qualitative and quantitative constraints are considered) problem in a logic decision diagram particularly at the different decision nodes of the diagram. Finally, verifying test results show that the algorithm is feasible and its optimal support project meets the needs of engineering practices. References | Related Articles | Metrics

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Unified Approach for Vibration Analyses of Annular Sector and Annular Plates with General Boundary Conditions SHI Xianjie (石先杰), LI Chunli* (李春丽), WEI Fayuan (魏发远) 2017, 22 (4):  449-458.  doi: 10.1007/s12204-017-1848-y Abstract ( 423 )   Abstract: This paper presents a unified approach for predicting the free and forced (steady-state and transient) vibration analyses of annular sector and annular plates with various combinations of classical and non-classical boundary supports. In spite of the types of the boundary restraints and the shapes of the plates, the admissible displacement function is described as a modified trigonometric series expansion, and four sine terms are introduced to overcome all the relevant discontinuities or jumps of elastic boundary conditions. Mathematically, the unification of various boundary value problems for annular sector and annular plates is physically realized by setting a set of coupling springs to ensure appropriate continuity conditions along the radial edges of concern. Numerous examples are presented for the free vibration analyses of annular sector and annular plates with different boundary restraints. With regard to the forced vibration analysis, annular sector and annular plates with different external excitations are examined. The accuracy, convergence and numerical robustness of the current approach are extensively demonstrated and verified through numerical examples which involve plates with various shapes and boundary conditions. References | Related Articles | Metrics

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Periodic Topology Optimization of Crane Boom Based on Improved Soft Kill Option Method WU Qinglong (吴青龙), ZHOU Qicai* (周奇才), ZHANG Richeng (张日成), XIONG Xiaolei (熊肖磊) 2017, 22 (4):  459-465.  doi: 10.1007/s12204-017-1859-8 Abstract ( 513 )   Abstract: An improved soft kill option (SKO) method is proposed to achieve the optimization design of tower crane boom. For a better optimization performance, a parabolic weight coefficient is suggested and the displacement constraint is taken into consideration. In order to eliminate the numerical instability phenomena like checkerboard and mesh dependence, element temperature filter function is added into SKO method. Through the optimization data comparison of rectangular cantilever plate, it is verified that the improved SKO method can achieve a better result with more uniform stress and higher efficiency. Based on the dimension and load parameters of QTZ63 tower crane boom, an optimization model is established, and a periodic SKO method is put forward to optimize this model. The optimization result of the crane boom can provide a new thought for tower crane boom design. References | Related Articles | Metrics

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Fault Diagnosis for Wind Turbine Based on Improved Extreme Learning Machine WU Bin1* (吴斌), XI Lifeng2 (奚立峰), FAN Sixia1 (范思遐), ZHAN Jian1 (占健) 2017, 22 (4):  466-473.  doi: 10.1007/s12204-017-1849-x Abstract ( 633 )   Abstract: A fault diagnosis method based on improved extreme learning machine (IELM) is proposed to solve the weakness (weak generalization ability, low diagnostic rate) of traditional fault diagnosis with feedforward neural network algorithm. This method fuses signal feature vectors, extracts six parameters as the principal component analysis (PCA) variables, and calculates correlation coefficient matrix among the variables. The weight values of control parameters in the extreme learning model are dynamically adjusted according to the test samples’ constantly changing. Consequently, the weight fixed drawback in the original model can be remedied. A fault simulation experiment platform for wind turbine drive system is built, eight kinds of fault modes are diagnosed by the improved extreme learning model, and the result is compared with that of other machine learning methods. The experiment indicates that the method can enhance the accuracy and generalization ability of diagnosis, and increase the computing speed. It is convenient for engineering application. References | Related Articles | Metrics

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Solving Service Selection Problem Based on a Novel Multi-Objective Artificial Bees Colony Algorithm HUANG Liping1,2* (黄丽萍), ZHANG Bin2 (张斌), YUAN Xun3 (苑勋),ZHANG Changsheng2 (张长胜), GAO Yan2 (高岩) 2017, 22 (4):  474-480.  doi: 10.1007/s12204-017-1860-2 Abstract ( 541 )   Abstract: Service computing is a new paradigm and has been widely used in many fields. The multi-objective service selection is a basic problem in service computing and it is non-deterministic polynomial (NP)-hard. This paper proposes a novel multi-objective artificial bees colony (n-MOABC) algorithm to solve service selection problem. A composite service instance is a food source in the algorithm. The fitness of a food source is related to the quality of service (QoS) attributes of a composite service instance. The search strategy of the bees are based on dominance. If a food source has not been updated in successive maximum trial (Max Trial) times, it will be abandoned. In experiment phase, a parallel approach is used based on map-reduce framework for n-MOABC algorithm. The performance of the algorithm has been tested on a variety of data sets. The computational results demonstrate the effectiveness of our approach in comparison to a novel bi-ant colony optimization (NBACO) algorithm and co-evolution algorithm. References | Related Articles | Metrics

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Rigid Sensor Allocation and Placement Technique for Reducing the Number of Sensors in Thermal Monitoring LI Xin* (李鑫), ZHOU Wei (周巍), JIANG Wen (蒋雯) 2017, 22 (4):  481-492.  doi: 10.1007/s12204-017-1861-1 Abstract ( 532 )   Abstract: Using embedded thermal sensors, dynamic thermal management (DTM) techniques measure runtime thermal behavior of high-performance microprocessors so as to prevent thermal runaway situations. The number of placed sensors should be minimized, while guaranteeing accurate tracking of hot spots and full thermal characterization. In this paper, we propose a rigid sensor allocation and placement technique for determining the minimal number of thermal sensors and the optimal locations while satisfying an expected accuracy of hot spot temperature error based on dual clustering. We analyze the false alarm rates of hot spots using the proposed methods in noise-free, with noise and sensor calibration scenarios, respectively. Experimental results confirm that our proposed methods are capable of accurately characterizing the temperatures of microprocessors. References | Related Articles | Metrics

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Design and Implementation of a Data-Driven Dynamical Reconfigurable Cell Array SHAN Rui1* (山蕊), LI Tao2 (李涛), JIANG Lin3 (蒋林),DENG Junyong3 (邓军勇), SHEN Xubang1 (沈绪榜) 2017, 22 (4):  493-503.  doi: 10.1007/s12204-017-1862-0 Abstract ( 537 )   Abstract: The nature of dataflow computation demands the heavy flow of tokens amongst computation nodes. Traditional reduced instruction-set computer (RISC) processors are not suitable for such style computation. Devices that use long wire buses are not suitable for dataflow either. Reconfigurable computing devices (RCDs) consist of data transfer wires and computing resources. With minor modifications, reconfigurable cells can be adopted to perform dataflow computation. A reconfigurable cell array (RCA) is presented in this paper and it is suitable for dataflow computation. This cell array has a dynamic reconfigurable storage model. The distinctive features of the architecture include dataflow reconfigurable cells and reconfigurable storage. Dataflow applications can be mapped easily and effectively onto the cells. Reconfigurable storage is mainly used to manage data access and transmission. Furthermore, computation and data management are separated. Meanwhile, dynamical reconfiguration is accomplished, when some clusters of cells work in configuration mode and other clusters work in computation mode. The dataflow graphs of some algorithms are mapped onto our architecture, and the performance results are compared with those of CPU and GPU. References | Related Articles | Metrics

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Long-Term Tracking Based on Spatio-Temporal Context LU Jiahui (陆佳辉), CHEN Yimin* (陈一民), ZOU Yibo (邹一波), ZOU Guozhi (邹国志) 2017, 22 (4):  504-512.  doi: 10.1007/s12204-017-1863-z Abstract ( 658 )   Abstract: Aiming at the problem that the fast tracking algorithm using spatio-temporal context (STC) will inevitably lead to drift and even lose the target in long-term tracking, a new algorithm based on spatio-temporal context that integrates long-term tracking with detecting is proposed in this paper. We track the target by the fast tracking algorithm, and the cascaded search strategy is introduced to the detecting part to relocate the target if the fast tracking fails. To a large extent, the proposed algorithm effectively improves the accuracy and stability of long-term tracking. Extensive experimental results on benchmark datasets show that the proposed algorithm can accurately track and relocate the target though the target is partially or completely occluded or reappears after being out of the scene. References | Related Articles | Metrics