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08 October 2019, Volume 24 Issue 5 Previous Issue    Next Issue

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Negative Refraction at a Lossy Interface and a Bold Hypothesis via Complex Frequency YIN Cheng (殷澄), KAN Xuefen (阚雪芬), SHAN Minglei (单鸣雷), CAO Zhuangqi (曹庄琪), WANG Xianping (王贤平) 2019, 24 (5):  545-550.  doi: 10.1007/s12204-019-2099-x Abstract ( 505 )   PDF (314KB) ( 138 )   We investigate the negative refraction effect at a planar interface of a highly absorptive material, where the direct experimental verification is difficult because of the loss-induced skin depth effect. An apparent contradiction occurs when we try to determine the group velocity direction by the method of equifrequency contours (EFCs) in detail. This contradiction forbids any physical solution to be found for negative refraction. We conclude that this paradox is mainly caused by the definition of complex wavevector k which is conventionally adopted in the case of complex permittivity. The complex wavevector may result in ambiguously defined optical path, which limits the application of the classical Snell's law. We propose a bold suggestion that the complex wavevector k should be replaced by a complex frequency ω. Therefore, the optical path can always be defined as real. The proposed hypothesis is capable of resolving the contradiction about the loss-induced negative refraction, and the obtained theoretical prediction fits well with the reported experimental results. References | Related Articles | Metrics

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Multi-Image Restoration Method Combined with Total Generalized Variation and lp-Norm Regularizations REN Xuanguang (任炫光), PAN Han (潘汉), JING Zhongliang (敬忠良), GAO Lei (高磊) 2019, 24 (5):  551-558.  doi: 10.1007/s12204-019-2113-3 Abstract ( 523 )   PDF (2413KB) ( 133 )   Image restoration is an important part of various applications, such as computer vision, robotics and remote sensing. However, recovering the underlying structures of the latent image contained in multi-image is a challenging problem because of the need to develop robust and fast algorithms. In this paper, a novel problem formulation for multi-image restoration problem is proposed. This novel formulation is composed of multi-data fidelity terms and a composite regularizer. The proposed regularizer consists of total generalized variation (TGV) and lp-norm. This multi-regularization method can simultaneously exploit the consistence of image pixels and promote the sparsity of natural signals. To deal with the resulting problem, we derive and implement the solution using alternating direction method of multipliers (ADMM). The effectiveness of our method is illustrated through extensive experiments on multi-image denoising and inpainting. Numerical results show that the proposed method is more efficient than competing algorithms, achieving better restoration performance. References | Related Articles | Metrics

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Slamming and Green Water Loads on Bow-Flare Ship in Regular Head Waves Investigated by Hydroelasticity Theory and Experiment JIAO Jialong (焦甲龙), ZHAO Yulin (赵玉麟), CHEN Chaohe (陈超核), LI Xiaochen (李晓晨) 2019, 24 (5):  559-570.  doi: 10.1007/s12204-019-2114-2 Abstract ( 615 )   PDF (1890KB) ( 124 )   With the development of ships towards large scale, high speed and light weight, ship hydroelastic responses and slamming strength issues are becoming increasingly important. In this paper, a time-domain nonlinear hydroelasticity theory is developed to predict ship motion and load responses in harsh regular waves. Hydrostatic restoring force, wave excitation force and radiation force are calculated on the instantaneously wetted body surface to consider the nonlinear effects caused by large amplitude motions of ship in steep waves. A twodimensional (2D) generalized Wagner model and a one-dimensional (1D) dam-breaking model are used to estimate the impact loads caused by bow flare slamming and green water on deck, respectively; the impact loads are coupled with the hydroelastic equation in time-domain. Moreover, segmented model tests are carried out in a towing tank to investigate the wave and slamming loads acting on the hull sailing in harsh regular head waves and also validate the numerical results. References | Related Articles | Metrics

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Research and Implementation of Beidou-3 Satellite Multi-Band Signal Acquisition and Tracking Method CHEN Shuhao (陈树浩), MAO Xuchu (茅旭初) 2019, 24 (5):  571-578.  doi: 10.1007/s12204-019-2115-1 Abstract ( 507 )   PDF (1156KB) ( 128 )   A new acquisition and tracking method is proposed for signal processing under the new signal system structure of Beidou-3 navigation satellite system (BDS-3). By starting with the analysis of the characteristics and signal structure of the new signal, the local replica of the ranging code and the study of the characteristics of the ranging code are completed, which proves that the method in this paper can be used in the subsequent acquisition and tracking process. The fast Fourier transformation (FFT) search based on longer coherence time and the adaptive phase-frequency switching carrier tracking loop are proposed for signals in different modulation modes. The actual signal of Beidou-3 satellite is sampled by local experiment, and the acquisition and tracking of the Beidou-3 satellite multi-band signal is finally completed. The tracking results verify the feasibility of the proposed acquisition and tracking method. References | Related Articles | Metrics

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Lasing Frequency Up-Conversion by Using Thermal Population NKONDE Sampa, JIANG Chun (姜淳) 2019, 24 (5):  579-583.  doi: 10.1007/s12204-019-2116-0 Abstract ( 379 )   We theoretically demonstrate a model which can be used to analyze frequency up-conversion of a laser wavelength by using thermal population. The proposed model uses a rate equation model of ytterbium-doped fiber with thermal population effect. The rate and power propagation equations are set up and numerically analyzed to elucidate the dependence of frequency up-conversion efficiency and thermal-optical conversion efficiency on ambient thermal power. The analytical techniques and numerical results show that using pump laser at 1 000 nm, the wavelength can be converted into 900 nm with an up-conversion quantum efficiency of about 99.97% and a cooling efficiency of about 11.1%. This theoretical model is a promising candidate for vast applications in energyefficient laser and energy-utilizing field. References | Related Articles | Metrics

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Conceptual Design of Screening System for Congenital Heart Disease YU Qin (余秦), CUI Yanping (崔燕萍), ZHAO Pengjun (赵鹏军), ZHANG Zhinan (张执南) 2019, 24 (5):  584-590.  doi: 10.1007/s12204-019-2117-z Abstract ( 449 )   PDF (1946KB) ( 107 )   Congenital heart disease (CHD), one of the main causes of infant mortality, should be screened as early as possible. However, the current screening method, auscultation, strongly depends on the doctors’ experience, and the contradiction between limited medical resource and growth of population becomes sharp. This study presents a systematic approach for the conceptual design of a novel screening system. Research and interview are carried out to determine user requirements. Quality function deployment (QFD) with consideration of related products, patent and research is implemented to find out the key user requirements of existing screening device and the order of design descriptors. With the key requirements confirmed, several concepts which focus on satisfying the key requirements are brought out. The final concept of the screening system is chosen by the application of Pugh decision matrix. The implementation of the conceptual design shows that the designed system satisfies the user requirements well. References | Related Articles | Metrics

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Spray Characteristics with High-Speed Tomographic Particle Image Velocimetry Under Non-Flash and Flash Boiling Conditions XU Hongchang (徐宏昌), LIU Shuangzhai (刘双寨), PAN Haoxing (潘浩星) 2019, 24 (5):  591-596.  doi: 10.1007/s12204-019-2118-y Abstract ( 448 )   PDF (6187KB) ( 115 )   Compared with port fuel injection engines, direct injection (DI) gasoline engine is becoming the mainstream of gasoline engines because of its higher fuel economy and excellent transient response. It has been proven that fuel spray characteristics in DI engines are crucial to the performance and emission quality of the engine. Flash boiling spray has great potential to achieve high fuel economy and low emission by dramatically improving the fuel atomization and vaporization and it has different spray-air interaction behavior as compared with non-flash boiling one, while its mechanism is more complex as compared with subcooled spray. We investigate the time-resolved spatial velocity field of the spray using 2-camera high-speed 3D3C (3-dimension 3-component) tomographic particle image velocimetry (PIV) diagnostic technique. A 10mm thick laser sheet is used to illuminate the fuel spray. Characteristics of both non-flash and flash boiling sprays are studied. A single-hole injector is mounted within a heat exchanger so that different fuel temperature can be accessed. In the experiment, n-pentane is used as the fuel. For the non-flash boiling spray, the velocity field of the liquid spray is mostly consistent to the injection direction. With the increase of the degree of superheat (DoS), the overall velocity scale decreases especially at the spray tip. Meanwhile, larger swirls occur at the lower part of the flash boiling spray, which means stronger spray-air interaction occurs at a higher DoS. References | Related Articles | Metrics

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Distributed Power Control Considering Different Behavioural Responses of Electric Vehicle Drivers in Photovoltaic Charging Station ZHANG Yuanxing (张元星), JIANG Bing (江冰), YAN Huaguang (闫华光), LI Taoyong (李涛永), ZHANG Jing(张晶), LIU Yongxiang (刘永相), XIAO Yuhu (肖宇华) 2019, 24 (5):  597-604.  doi: 10.1007/s12204-019-2100-8 Abstract ( 481 )   PDF (306KB) ( 113 )   A distributed energy management in a photovoltaic charging station (PV-CS) is proposed on the basis of different behavioural responses of electric vehicle (EV) drivers. On the basis of the provider or the consumer of the power, charging station and EVs have been modeled as independent players with different preferences. Because of the selfish behaviour of the individuals and their hierarchies, the power distribution problem is modeled as a noncooperative Stackelberg game. Moreover, Karush-Kuhn-Tucker (KKT) conditions and the most socially stable equilibrium are adopted to solve the problem in hand. The consensus network, a learning-based algorithm, is utilized to let the EVs communicate and update their own charging power in a distributed fashion. Simulation analysis is supported to show the static and dynamic responses as well as the effectiveness and workability of the proposed charging power management. For the sake of showing the responses of EV drivers, different behavioural responses of EVs’ drivers to the discount on the charging price offered by the station are introduced. The simulation results show the effectiveness of the proposed energy management. References | Related Articles | Metrics

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Design of Micropipette System with High Precision for Small Enzyme Immunoassay Analyzer SHANG Zhiwu (尚志武), ZHOU Xiangping (周湘平), LI Cheng (李成), ZHOU Xinyu (周昕宇) 2019, 24 (5):  605-615.  doi: 10.1007/s12204-019-2104-4 Abstract ( 511 )   PDF (1062KB) ( 108 )   A small auto micropipette system is developed to improve the reliability and accuracy of the automatic enzyme immunoassay analyzer’s microscale pipetting system. A sophisticated injection mechanism is designed by the means of dislocation parallel distribution of the screw and injector piston rod. It possesses the function of pipetting, taking and removing the pipette tips. In the control system, STM32 controller is used, controlling the single-axis S-type acceleration/deceleration algorithm and multi-threaded coordinated motion. The acceleration/ deceleration curves are analyzed and optimized by using the method of segmentation; a minimum injection rate of 1 μL and a step rate of 0.05μL are realized. The method of digital image processing is used to detect the amount of pipetting in micro-pipetting quantitatively. The liquid area is extracted by background contrast method, and the liquid volume in the tip is obtained by combining the geometric characteristics of the disposable tip, when the pipetting capacity is not qualified to carry out specific guidance on the pipetting system, and avoid the blocking needle, bubble and other abnormal pipetting phenomenon on the impact of pipetting accuracy. The experimental results show that the combination of the automatic sampling system and the image flow detection system can effectively improve the precision and reliability of the micro-pipetting system. Finally, the injection accuracy of the system at the test points with 10, 50 and 100 μL liquid volumes reaches 1.8%, 1.28% and 1.15% respectively. References | Related Articles | Metrics

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Low Speed Bearing Fault Diagnosis Based on EMD-CIIT Histogram Entropy and KFCM Clustering ZHANG Ke (张珂), LIN Tianran (林天然), JIN Xia (金霞) 2019, 24 (5):  616-621.  doi: 10.1007/s12204-019-2108-0 Abstract ( 497 )   PDF (687KB) ( 115 )   In view of weak defect signals and large acoustic emission (AE) data in low speed bearing condition monitoring, we propose a bearing fault diagnosis technique based on a combination of empirical mode decomposition (EMD), clear iterative interval threshold (CIIT) and the kernel-based fuzzy c-means (KFCM) eigenvalue extraction. In this technique, we use EMD-CIIT and EMD to complete the noise removal and to extract the intrinsic mode functions (IMFs). Then we select the first three IMFs and calculate their histogram entropies as the main fault features. These features are used for bearing fault classification using KFCM technique. The result shows that the combined EMD-CIIT and KFCM algorithm can accurately identify various bearing faults based on AE signals acquired from a low speed bearing test rig. References | Related Articles | Metrics

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Reliability Evaluation Method Based on Double Beta Prior Distribution for the Pyrotechnic Device CHENG Li (程立), YANG Yuanyuan (杨媛媛), MU Huina (穆慧娜), YANG Xiaoyu (杨小玉), LI Li (李立), WEN Yuquan (温玉全) 2019, 24 (5):  622-627.  doi: 10.1007/s12204-019-2102-6 Abstract ( 514 )   PDF (196KB) ( 104 )   On the basis of the Bayesian principle, a method of selecting the double beta distribution as a priori distribution is proposed for the system reliability evaluation when the available field test samples are small for pyrotechnic device. Under the condition of different field and historical data, the mean square error (MSE) and coverage ratio (CR) of the reliability evaluation are compared by numerical simulation when the conjugate distribution and uniform distribution are selected as the priori distribution. Finally, the rationality and engineering applicability of the proposed method are verified through an example of the reliability evaluation of a typical pyrotechnic device. References | Related Articles | Metrics

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Robust Optimization Design of Metro Handrails LI Yonghua (李永华), ZHANG Xiaodan (张晓丹), ZHI Pengpeng (智鹏鹏) 2019, 24 (5):  628-631.  doi: 10.1007/s12204-019-2119-x Abstract ( 494 )   PDF (326KB) ( 105 )   This paper presents the robust design and response surface method (RSM) based on finite element analysis for the optimization design of metro handrails. The response surface can be created for each output parameter. Sequential quadratic programming is used for the optimization of metro handrails. Taguchi design is employed to investigate the sensitive controlling factors for the strength and mass of metro handrails, by taking the material density, the column and cross bar thickness as controlling factors, and the acceleration, the elastic modulus and the fluctuation of material density as uncontrollable factors. Then, the best combination of controlling factors is found. The results by different methods show that the method of Taguchi design can improve the robustness of the structural performance and reduce the mass. References | Related Articles | Metrics

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Torsion Failure Analysis of Galvanized Steel Wires for Transmission and Distribution Lines Based on ANSYS Numerical Simulation WANG Man (王曼), ZHANG Xiaomin (张晓敏), LONG Peng (龙鹏), JIANG Yu (蒋渝) 2019, 24 (5):  632-639.  doi: 10.1007/s12204-019-2112-4 Abstract ( 443 )   PDF (10919KB) ( 111 )   This study provides a detailed failure analysis of galvanized steel wires (3mm in diameter) for a 35 kV transmission and distribution line, which was carried out by combining the conventional material analysis methods with the finite element method (FEM). It is found that the failed material had good plasticity (5% in elongation), and under the soft torsion loading condition (0.75 in stress state soft coefficient), the ductile fracture should occur on the material. Additionally, the theoretical number of torsions calculated by the FEM was 26.2 times, while the actual number of torsions achieved by the test was only 2.2 times and the local fracture surface exhibited brittle fracture characteristics. The results showed that the local torsion brittle fracture of the material with good plasticity was caused by triaxial stress in the torsion condition, which led to the formation of cavity in the pulling stress area in the material’s center, and the finite element calculation results indicated that the stress state soft coefficient at the cavity was distributed between 0.31 and 0.38, and the stress concentration at the cavity was more than twice the normal value. Besides, the Widmanstatten structure formed as the improper hot working process is the corresponding structural reason. References | Related Articles | Metrics

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Experiment on Seismic Performance of Frame-Masonry Horizontal Hybrid Structure Based on Shaking Table Test ZHENG Guochen (郑国琛), XU Hangli (许航莉), WU Yingxiong (吴应雄) 2019, 24 (5):  640-646.  doi: 10.1007/s12204-019-2082-6 Abstract ( 424 )   PDF (1250KB) ( 121 )   Frame-masonry horizontal hybrid structure is a new type of self-built residence in the rural areas of Fujian Province in recent years. A shaking table test for 1/2 scale model is carried out on the basis of one representative rural structure, and the dynamic characteristics and seismic responses of this experimental model are measured. As a supplement, the finite element model of the prototype structure is built by ANSYS software, and simulation and test results are contrasted and analyzed. The results show that according to this structure, the beam-column joint of the frame part has stress concentration and the destruction pattern of the masonry part is similar to brick-masonry structure. There are obvious differences in lateral stiffness of each floor and direction, and the mass center does not coincide with the stiffness center, which can lead to excessive torsion and story drift of this structure under earthquakes of a certain intensity. Because of poor construction quality, unfavorable structural measures and irrational structural system in present rural areas, there is a potential safety threat with this type of structures in highly seismic region. Some suggestions for strengthening and retrofitting frame-masonry horizontal hybrid structures are pointed out. References | Related Articles | Metrics

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Wall Thinning Characteristics of Ti-3Al-2.5V Tube in Numerical Control Bending Process HUANG Tao (皇涛), WANG Kun (王锟), ZHAN Mei (詹梅), GUO Junqing (郭俊卿), CHEN Xuewen (陈学文), CHEN Fuxiao (陈拂晓), SONG Kexing (宋克兴) 2019, 24 (5):  647-653.  doi: 10.1007/s12204-019-2079-1 Abstract ( 476 )   PDF (656KB) ( 114 )   A finite element (FE) model for the numerical control (NC) bending of Ti-3Al-2.5V titanium alloy seamless tube is established, considering the variation in the contractile strain ratio (CSR) and elastic modulus (E). The wall thinning characteristics of Ti-3Al-2.5V tube under different geometric and process conditions were investigated. The results showed that the CSR-E variation can change the wall thickness, but has no remarkable effect on the change characteristics. The reasonable parameter ranges are as follows: a bending-radius range not less than 1.5 times the outer diameter, a bend angle up to 180?, and a mandrel extension of 0—3mm. The friction coefficient between the pressure die and the tube should be in the range of 0.20—0.35, and between the bending die and the tube should be in the range of 0.05—0.15. As long as the performance meets the requirements, the relative push-assistant speed should be as small as possible. References | Related Articles | Metrics

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Monocular Dynamic Machine Vision-Based Pearl Shape Detection WANG Yuzong (王毓综), DENG Fei (邓飞), ZHAO Daxu (赵大旭), YE Jiaying (叶佳英), WANG Peixin (王佩欣), SHOU Guozhong (寿国忠) 2019, 24 (5):  654-662.  doi: 10.1007/s12204-019-2103-5 Abstract ( 441 )   PDF (5541KB) ( 109 )   In terms of the requirement of automatically sorting pearls, the pearl contour feature extraction and shape recognition algorithm are studied in this paper to reckon with the rapid identification of pearls shape online, and a monocular dynamic machine vision-based pearl shape detection device is designed. Through blowing, the pearl is suspended in a funnel shaped container and flipped rapidly in the device. The entire surface image of the pearl to be measured can be promptly grasped by the camera placed right above the funnel. The results of illumination experiments conducted from different angles indicate that the image contour acquired by the medium angle illumination is better extracted. The pearl shape test indicates that the method is incorporated with the inflatable suspension device to classify the pearls into seven types according to the national standard, and additionally the average error rate is confined under 5.38%. The shape characteristic of the pearl can be detected promptly and reliably, and accordingly the high-speed automatic sorting can be satisfied. References | Related Articles | Metrics

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Magnetic Tile Surface Defect Detection Based on Texture Feature Clustering LI Dan (李丹), NIU Zhongbin (牛中彬), PENG Dongxu (彭冬旭) 2019, 24 (5):  663-670.  doi: 10.1007/s12204-019-2101-7 Abstract ( 507 )   PDF (3195KB) ( 112 )   In the field of magnetic tile surface detection, artificial detection efficiency is low, and the traditional image segmentation algorithm cannot show good performance when the gray scale of the magnetic tile itself is small, or the image is affected by uneven illumination. In view of these questions, this paper puts forward a new clustering segmentation algorithm based on texture feature. This algorithm uses Gabor function spectra to represent magnetic tile surface texture and then uses a user-defined local product coefficient to modify Gabor energy spectra to get the center number of fuzzy C-means (FCM) clustering. Moreover, the user-defined Gabor energy spectra image is segmented by clustering algorithm. Finally, it extracts the magnetic tile surface defects according to the changes of regional gray characteristics. Experiments show that the algorithm effectively overcomes the noise interference and makes a good performance on accuracy and robustness, which can effectively detect crack, damage, pit and other defects on the magnetic tile surface. References | Related Articles | Metrics

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Intercept Mode Suitable for the Space-Based Kinetic Energy Interceptor DUAN Junhong (端军红), LIU Yuefeng (刘跃峰), WAN Kaifang (万开方) 2019, 24 (5):  671-680.  doi: 10.1007/s12204-019-2105-3 Abstract ( 560 )   PDF (346KB) ( 104 )   The intercept mode of space-based kinetic energy interceptor (KEI) is an essential problem to be solved in the concept design of KEI and is closely related to the KEI’s detailed designing and practical applications. However, this problem has not yet been investigated systematically and comprehensively. A suitable intercept mode for the KEI is proposed in this research. The intercept mode consists of three basic elements: the specific operation procedure, general scheme for the intercept trajectory, and mathematical model of the intercept mode. Numerical example is provided to demonstrate the feasibility and effectiveness of the intercept mode. The intercept mode proposed in this research is capable of achieving a rapid intercept, and is applicable to the universal space interception. References | Related Articles | Metrics