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15 December 2019, Volume 24 Issue 6 Previous Issue    Next Issue

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Synthesis and Applications of Porous Glass ZHU Benbi (朱本必), ZHANG Zhijian (张志坚), ZHANG Wang (张旺), WU Yu (吴昱), ZHANG Jianzhong (章建忠), IMRAN Zada, ZHANG Di (张荻) 2019, 24 (6):  681-698.  doi: 10.1007/s12204-019-2131-1 Abstract ( 480 )   PDF (13343KB) ( 132 )   Porous materials have received significant attention for catalyst, electrochemical energy storage, sensing and compound capture. Large surface area and connected inner channel make porous materials outstanding in the applications of catalyst, batteries and biomedicine. Glass is a traditional material and has the advantages of high stability and other physical properties. By combining the advantages of porous materials and glass, porous glass has been researched widely and applied to many leading-edge fields, such as batteries and sensors. This review presents common methods for synthesizing porous glass, including phase separation process (PSP), direct leaching process (DLP) of acid, sintering and so on. Three main steps for fabrication of each process are concluded. The recent applications are support, capturer and matter transport, and they are highlighted in this review. Future directions for preparing these materials are also discussed. References | Related Articles | Metrics

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Transfer Learning Based on Joint Feature Matching and Adversarial Networks ZHONG Haowen (钟昊文), WANG Chao (王超), TUO Hongya (庹红娅), HU Jian (胡健), QIAO Lingfeng (乔凌峰), JING Zhongliang (敬忠良) 2019, 24 (6):  699-705.  doi: 10.1007/s12204-019-2132-0 Abstract ( 547 )   PDF (2094KB) ( 104 )   Domain adaptation and adversarial networks are two main approaches for transfer learning. Domain adaptation methods match the mean values of source and target domains, which requires a very large batch size during training. However, adversarial networks are usually unstable when training. In this paper, we propose a joint method of feature matching and adversarial networks to reduce domain discrepancy and mine domaininvariant features from the local and global aspects. At the same time, our method improves the stability of training. Moreover, the method is embedded into a unified convolutional neural network that can be easily optimized by gradient descent. Experimental results show that our joint method can yield the state-of-the-art results on three common public datasets. References | Related Articles | Metrics

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Mode Tracking Scheme Among Remeshed Models for Structural Optimization LIU Jun (刘俊), DING Ziqi (丁子祈), LU Qi (陆麒), HAN Xianhong (韩先洪) 2019, 24 (6):  706-715.  doi: 10.1007/s12204-019-2133-z Abstract ( 507 )   PDF (1798KB) ( 84 )   Mode tracking is required in the structural optimization when the frequencies of certain specified modes must be maintained within a suitable range. A simple tracking method employing the mode number is invalid or misleading when local modes appear or disappear during mesh updating. In this work, a mode tracking scheme combining the nearest neighbor method (NNM) with the modal assurance criterion (MAC) is proposed. Several NNM algorithms are compared, and the k-dimensional tree (kd-tree) NNM is used to transform eigenvectors (mode shapes) from different scales to identical one. A threshold determination method is implemented for the MAC to assess the similarities in all the calculated modes. On the basis of the mode tracking scheme, specified modes can be tracked between different finite element method (FEM) models which have different meshes and optimized shapes. The effectiveness is verified through an example of shape optimization using an electric motor structure. References | Related Articles | Metrics

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Neural Firing Mechanism Underlying Two-Electrode Discrimination by 3D Transcutaneous Electrical Nerve Stimulation Computational Model YE Shuan (叶栓), ZHU Kaihua (祝凯华), LI Peng (李鹏), SUI Xiaohong (隋晓红) 2019, 24 (6):  716-722.  doi: 10.1007/s12204-019-2134-y Abstract ( 453 )   PDF (2777KB) ( 96 )   Transcutaneous electrical nerve stimulation (TENS) has been widely used for sensory feedback which is a key consideration of improving the performance of prosthetic hands. Two-electrode discriminability is the key to realize high-spatial-resolution TENS, but the neural firing mechanism is not clear yet. The goal of this research is to investigate the neural firing patterns under two-electrode stimulation and to reveal the potential mechanisms. A three-dimensional (3D) model is established by incorporating Aβ fiber neuron clusters into a layered forearm structure. The diameters of the stimulating electrodes are selected as 5, 7, 9 and 12 mm, and the two-electrode discrimination distance (TEDD) is quantified. It is found that a distant TEDD is obtained for a relatively large electrode size, and 7mm is suggested to be the optimal diameter of stimulating electrodes. The present study reveals the neural firing patterns under two-electrode stimulation by the 3D TENS model. In order to discriminate individual electrodes under simultaneous stimulation, no crosstalk of activated Aβ fibers exists between two electrodes. This research can further guide the optimization of the electrode-array floorplan. References | Related Articles | Metrics

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Reduction of Brain Injury After Stroke in Hyperglycemic Rats via Fasudil Pretreatment LIU Jianyu (刘健宇), MU Zhihao (木志浩), WANG Liping (王丽萍), WEN Ruoxue (闻若雪), WANG Yongting (王永亭), YANG Guoyuan (杨国源), ZHANG Zhijun (张志君) 2019, 24 (6):  723-731.  doi: 10.1007/s12204-019-2127-x Abstract ( 350 )   PDF (4777KB) ( 90 )   Diabetes is usually associated with cerebrovascular disease, especially stroke. In practice, fasudil is widely accepted to be applied for the treatment of vascular disease. This article demonstrates the study concentrating on the effects of fasudil pretreatment on the prognosis of diabetic stroke. 250—300 g Sprague- Dawley rats were randomly divided into three groups, non-diabetic stroke group, diabetic stroke group, and fasudil pretreatment group. The rats of diabetes group were treated with intraperitoneal injection of streptozotocin (60 mg/kg), in the meantime the same dose of citrate buffer was injected into those of the control group. The rats of the fasudil group received daily fasudil intraperitoneal injection at 10 mg/kg for three consecutive weeks. After four weeks, all the rats of the experimental group were treated with middle cerebral artery occlusion for 90 min. After sacrifice, the fresh brain samples were collected for following experiments, including infarct volume, edema volume, blood-brain barrier (BBB), which were detected by immunohistochemistry. Inflammatory factors were examined by real-time polymerase chain reaction (RT-PCR) using tissue Ribonucleic Acid (RNA). The concentration of blood glucose is 15 mmol/L or more, which proved that the diabetes model was a success. Fasudil pretreatment decreases the percentage of stroke mortality of diabetes from 43.75% to 31.25%, while the infarction volume decreases from 52.95% ± 12.7% to 45.97% ± 6.7%. Gap formation of tight junction and Immunoglobulin G (IgG) leakage were reduced (P < 0.05), and the expression of inflammatory factors decreases (P < 0.05) in fasudil pretreatment after diabetic stroke. Diabetes aggravates the mortality of cerebral ischemic rats. Prolonged fasudil pretreatment can reduce mortality of diabetic stroke, decrease cerebral infarction volume and undermine inflammatory factors expression, and protect the BBB. References | Related Articles | Metrics

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Experimental Investigation into the Effect of Roll Amplitude on Roll Damping ZHANG Xiaohui (张晓慧), GU Xiechong (顾解忡), MA Ning (马宁), WANG Yifan (王一凡), WU Zeren (吴泽仁) 2019, 24 (6):  732-738.  doi: 10.1007/s12204-019-2120-4 Abstract ( 421 )   PDF (4947KB) ( 84 )   An in-house large eddy simulation (LES) code has been developed in the previous study. In order to validate the code for simulation of roll motion, effect of roll amplitude on forced roll damping is experimentally investigated in a circulating water channel at Shanghai Jiao Tong University (SJTU). KRISO very large crude carrier 2 (KVLCC2) is taken as a target ship, and a model with a scale of 1 : 128.77 is manufactured. Tests are carried out for the ship model at shallow draft with frequencies around its natural roll frequency, where natural roll frequency is attained via free roll decay. Six forced roll tests with roll amplitudes ranging from 1? to 4? are performed experimentally, and three forced roll motions are simulated with the in-house LES code for middle section of the ship model. Discrepancies between the computed roll damping coefficients and the ones from forced roll tests are quite small. By means of particle image velocimetry (PIV), velocity fields in the vicinity of the ship model, and generation and evolution of vortices near the ship bilge are measured in detail. It is shown that roll amplitude has a significant effect on the vortex behavior, and therefore on the magnitude of roll damping coefficient. Further experimental and numerical investigation into roll motions with large amplitudes is planned. References | Related Articles | Metrics

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Zero-Inflated Exponential Distribution of Casualty Rate in Ship Collision HUANG Daozheng (黄道正), HU Hao (胡昊), LI Yizhou (李逸舟) 2019, 24 (6):  739-744.  doi: 10.1007/s12204-019-2121-3 Abstract ( 338 )   PDF (214KB) ( 78 )   There are two weaknesses in current researches into human casualty of ship collision. One is that the range of injuries or fatalities is restricted to the maximum number of casualties in a particular sample, which may not cover all the possible numbers of casualties in the future. International Maritime Organization (IMO) employed the injured or dead percentage of all the persons on board to represent casualties, but it only provided several discrete values to quantify human losses in different scenarios. The other is that the assumption that the distributions of the injuries or fatalities follow certain distribution, such as negative binomial and Poisson distributions is left to be statistically tested. Firstly, this study considers casualty rate, including injury and fatality rates, as random variables; the interval of the variables are from 0 to 1. Then, the distributions of the variables are investigated using historical data. From historical data, we can find that there are many zeros. Zeroinflated models are proved to be effective in processing data with inflated zeros. Furthermore, the probability density of the variables decreases rapidly as the casualty rate becomes larger. Thus, zero-inflated exponential distribution is assumed to fit the data. The parameters of zero-inflated exponential distribution are calibrated by maximum likelihood estimation (MLE) method. Finally, the assumption is tested by chi-square test. The zeroinflated exponential distribution can be used to generate human losses as a part of consequences in the simulation of ship collision risk. References | Related Articles | Metrics

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Dynamic Effect Research of Cable-Lead-In Rod on Towed System WANG Fei (王飞), TU Weimin (涂卫民), DENG Deheng (邓德衡), WU Xiaofeng (吴小峰) 2019, 24 (6):  745-753.  doi: 10.1007/s12204-019-2135-x Abstract ( 381 )   PDF (312KB) ( 84 )   This paper aims to research the cable-lead-in rod effect on a towed system through mathematical modeling and numerical simulations. The rod dynamics, as a key part of this study, is modeled using the combination of cable node governing equations and kinematic constraint conditions. As the first attempt to analyze such a problem, the rod is simply treated as an elastic cable segment so as to be incorporated into the dynamics of the cable, and a set of algorithm is then proposed based on the kinematic constraint conditions to fully describe its motions. Meanwhile, the cable and the underwater vehicle are modeled by the traditional lumped mass method and the 6 degree-of-freedom maneuverability equations for submarines respectively; the coupling boundary conditions besides the rod dynamics are also given to form the whole system’s model. Several numerical cases are performed to investigate the rod effect on the system in different maneuver situations. Some meaningful conclusions are drawn through comparative analysis. References | Related Articles | Metrics

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Theoretical Modelling of Cascaded Er3+-Doped, Tm3+-Doped and Nd3+-Doped Fibers for 0.4 to 2.0 μm Emission Spectra NKONDE Sampa, JIANG Chun (姜淳) 2019, 24 (6):  754-762.  doi: 10.1007/s12204-019-2122-2 Abstract ( 314 )   PDF (355KB) ( 79 )   We present a cascaded system designed with Er3+-doped, Tm3+-doped and Nd3+-doped fibers to realize amplified spontaneous emission (ASE) spectra covering 0.4—2.0 μm. The system is excited with a pump laser emitting 808 nm photons with 500mW pump power. The emission spectra of the cascaded system covering 0.4—2.0 μm are realized with the Er3+, Tm3+ and Nd3+ ion doping densities optimized to 8 × 1019, 2 × 1020 and 8 × 1020 ion/m3, respectively, and the fiber length optimized to 1 m. Numerical methods reveal that the peak ASE power for the cascaded system can reach 20.9mW. A minimum ASE power of 4.39mW is attainable. Using numerical calculations and analytical techniques, we provide a detailed insight into optimized Er3+-doped, Tm3+- doped and Nd3+-doped fiber lengths and their doping concentrations for ASE power spectra covering 0.4—2.0 μm. We believe that the cascaded system can potentially provide significant applications in various optical fields which include but not limited to wavelength-division multiplexing, various optical communications and other salient medical imaging processes. References | Related Articles | Metrics

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Optimization of Numerical Control Program and Machining Simulation Based on VERICUT ZHOU Feng (周峰), ZHANG Zixu (张紫旭), WU Chang (武畅), TIAN Xin (田鑫), LIU Haotian (刘昊天), HE Weidong (何卫东) 2019, 24 (6):  763-768.  doi: 10.1007/s12204-019-2109-z Abstract ( 483 )   PDF (236KB) ( 84 )   In the machining process of large-scale complex curved surface, workers will encounter problems such as empty stroke of tool, collision interference, and overcut or undercut of the workpieces. This paper presents a method for generating the optimized tool path, compiling and checking the numerical control (NC) program. Taking the bogie frame as an example, the tool paths of all machining surface are optimized by the dynamic programming algorithm, Creo software is utilized to compile the optimized computerized numerical control (CNC) machining program, and VERICUT software is employed to simulate the machining process, optimize the amount of cutting and inspect the machining quality. The method saves the machining time, guarantees the correctness of NC program, and the overall machining efficiency is improved. The method lays a good theoretical and practical foundation for integration of the similar platform. References | Related Articles | Metrics

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Recognition Algorithm and Risk Assessment of Airport Hotspots XIA Zhenghong (夏正洪), ZHENG Bo (郑波), WAN Jian (万健), ZHU Xinping (朱新平) 2019, 24 (6):  769-774.  doi: 10.1007/s12204-019-2110-6 Abstract ( 405 )   PDF (399KB) ( 80 )   The hotspot recognition algorithm is proposed based on a potential collision in order to study the aircraft taxi conflicts in large airports. The spatial and temporal distribution characteristics of hotspots are analyzed based on the risk assessment model of hotspot constructed in this paper. Firstly, approaches for monitoring of the aerodrome movement were compared. The hotspot recognition algorithm taken into account of whether aircrafts’ taxi track has spatial and temporal overlap based on the aerodrome surveillance radar (ASR) data was presented, by identifying the hotspots through analyzing whether the aircrafts’ time of entering and exiting the same taxiway is overlap or not, and the heading difference and distance of the two aircrafts satisfy the specified threshold constraint condition. Then, the ASR data were divided into several parts, and then airport hotspots were recognized and the spatial and temporal distribution characteristics were analyzed. The risk assessment model of airport safety hotspots was constructed which is taken into account of the conflict probability and its severity consequence. Finally, based on the risk grade assessment criteria and hotspots’ risk value, the risk grade ranking of hotspot in one airport of China was evaluated and designated. According to the result, the spatial and temporal distribution characteristics of airport hotspots were varied with the variation of airport traffic flow and operational mode of runway, which shows that the hotspots have the characteristics of dynamic periodicity and diurnal variation. And the risk assessment results were consistent with experts’ opinions and actual operation condition, which verified the rationality of the hotspot recognition algorithm, risk assessment model as well as the risk grade ranking criteria. References | Related Articles | Metrics

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Preliminary Application of Scale Transformation Stochastic Resonance in Dual-Sequence Frequency Hopping System LIU Guangkai (刘广凯), SUN Huixian (孙慧贤), QUAN Houde (全厚德), CUI Peizhang (崔佩璋), ZHU Shilei (朱世磊), CHI Kuo (池阔) 2019, 24 (6):  775-781.  doi: 10.1007/s12204-019-2136-9 Abstract ( 374 )   PDF (1282KB) ( 80 )   Aiming at the detection failure of strong noise interference in the dual channel of the dual-sequence frequency hopping (DSFH), the scale transformation stochastic resonance (STSR) is applied for the first time, and the output signal to noise ratio (SNR) is raised effectively, at the same time, the symbol reception is completed for DSFH at low input SNR. Firstly, the radio frequency (RF) and intermediate frequency (IF) signals are analyzed based on the super-heterodyne reception of DSFH; secondly, the equations of probability density function (PDF), output power spectrum and SNR of the STSR output are derived for the IF signal; finally, the algorithm of the optimal matching STSR is proposed with the optimal matching parameters. The simulation results show that the algorithm can effectively solve the detection failure, as the global output SNR of DSFH is strongly improved that the output SNR can reach ?17.72 dB when the input SNR is ?20 dB after the processing of the optimal matching STSR. References | Related Articles | Metrics

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Composite Feedforward Compensation for Force Ripple in Permanent Magnet Linear Synchronous Motors YANG Chunyu (杨春雨), CHE Zhiyuan (车志远), ZHOU Linna (周林娜) 2019, 24 (6):  782-788.  doi: 10.1007/s12204-019-2111-5 Abstract ( 392 )   PDF (266KB) ( 91 )   This paper presents a method for compensating the force ripple in permanent magnet linear synchronous motors (PMLSMs) by adopting a composite feedforward compensation scheme. Firstly, the vector control system of PMLSMs is described, and various force disturbances influencing the electromagnetic thrust are analyzed. As a result, the mathematical model of the whole system considering the force ripple is established. Then, a novel composite feedforward compensation scheme is proposed, which consists of a recursive least squares (RLS) parameter identification component and two feedforward compensation loops corresponding to the reference position trajectory and the force ripple, respectively. Finally, the effectiveness and advantages of the proposed composite feedforward compensation are demonstrated by simulation. The main incentive of this paper is the combination with the composite feedforward compensation loop corresponding to the reference position trajectory to improve the compensation effect of force ripple in PMLSMs. References | Related Articles | Metrics

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Temperature Drop Model Based on Discrete Element Method for Simulating Damage of Bio-Cemented Sand by Cold Wave DUAN Yu (段宇), KIM Cholgyong (金哲景), XU Guobin (徐国宾) 2019, 24 (6):  789-798.  doi: 10.1007/s12204-019-2123-1 Abstract ( 324 )   PDF (4204KB) ( 118 )   The microbially cemented sand (MCS) material is a new building material with a broad research prospect, although the nationwide cold wave affects the mechanical properties of the material in the practical application. The microstructure of MCS is obtained by computed tomography (CT) and scanning electron microscope (SEM); the thermodynamic mathematical model is established by considering the particle shapes and bonding state based on direct element method (DEM). By studying the damage of temperature drop amplitude and cooling duration to MCS material under the effect of cold wave, the following conclusions are drawn. For a given temperature drop range, an increased cooling time can aggravate the material damage. In addition, a rapid drop in temperature can cause serious damage to the material. The cracks generated by the temperature stress propagate in the direction of the weaker component of the material. The DEM model can be better used to analyze the damage of the MCS structure induced by cold wave. References | Related Articles | Metrics

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Correction Method for Calculating Critical Plane Position of Geometric Discontinuity Steel Structure Under Multiaxial Loading LI Bin (李斌), WANG Xiuli (王秀丽), LIU Jianhui (刘俭辉), LANG Shanshan (郎珊珊) 2019, 24 (6):  799-804.  doi: 10.1007/s12204-019-2128-9 Abstract ( 469 )   PDF (527KB) ( 77 )   Critical plane method is one of the most promising approaches to predict the fatigue life when the structure is subjected to the multiaxial loading. The stress-strain status and the critical plane position for smooth specimens are calculated using theoretical approaches when the loading mode is a continuous function. However, because of the existence of stress concentration and the characteristic of multiaxial non-proportion, it is difficult to calculate the stress-strain status and the critical plane position of geometric discontinuity structure by theory method. In this paper, a new numerical simulation method is proposed to determine the critical plane of geometric discontinuity structure under multiaxial loading. Firstly, the strain status of dangerous point is analyzed by finite element method. Secondly, the maximum shear strain amplitude of arbitrary plane is calculated using coordinate transformation principle. Finally, the plane which has the maximum shear strain amplitude is defined as the critical plane. The critical plane positions are analyzed when loading mode and notch parameters are different. Meanwhile, the relationship between notch depth and associated parameters on critical plane as well as that between loading amplitude and associated parameters on critical plane are given quantitatively. References | Related Articles | Metrics

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Imprecise Probability Method with the Power-Normal Model for Accelerated Life Testing YIN Yichao(殷毅超), HUANG Hongzhong (黄洪钟), LIU Zheng (刘征) 2019, 24 (6):  805-810.  doi: 10.1007/s12204-019-2126-y Abstract ( 491 )   PDF (726KB) ( 87 )   We present a new nonparametric predictive inference (NPI) method using a power-normal model for accelerated life testing (ALT). Combined with the accelerating link function and imprecise probability theory, the proposed method is a feasible way to predict the life of the product using ALT failure data. To validate the method, we run a series of simulations and conduct accelerated life tests with real products. The NPI lower and upper survival functions show the robustness of our method for life prediction. This is a continuous research, and some progresses have been made by updating the link function between different stress levels. We also explain how to renew and apply our model. Moreover, discussions have been made about the performance. References | Related Articles | Metrics