An Algorithm for Vein Matching Based on Log-polar Transform

Wei Yan,Jianbin Xie,Peiqin Li,Tong Liu,Xiaoguang Guo 한국산학기술학회 2013 SmartCR Vol.3 No.5

This article discusses a new algorithm for vein matching based on log-polar transform to address problems that occur with the changing of finger position and from differences between imaging devices for current vein matching algorithms. The new algorithm first extracts the feature area, which contains enough characteristics for image matching, depending on the structure of the finger vein ridge alignment. It then calculates the degree of similarity between the log-polar transform results of the model image feature areas and the sample image, and finally analyzes the result by the degree of similarity and the relationship of relative positions between feature areas. Experiments show that the algorithm is robust for rotating and zooming images of the finger vein.

Level Set Based Path Planning Using a Novel Path Optimization Algorithm for Robots

Xiaoguang Zhang,Wei Zhang,Hui Li,Mingqin Liu,류성기 한국정밀공학회 2018 International Journal of Precision Engineering and Vol.19 No.9

In order to decrease the path length and control the minimum distance between the path and the obstacles when the level set based path planning algorithm is adopted , a new path optimization algorithm named elastic particle is proposed in this paper. Firstly, the iteration expression of optimization algorithm is deduced by active contour theory. Secondly, to ensure the convergence of algorithm, the relation among each item in the algorithm expression is analyzed and its convergence condition is determined. At last, level set algorithm is improved so that the smoothness of the initial path and the convergence speed of the algorithm are improved. In addition, a method named the nearest boundary distance is put forward to accelerate the operation speed of the algorithm. What’s more, memory pool and binary sort tree are adopted in the code to further reduce the running time of this algorithm. The optimal values of the algorithm parameters are analyzed via the simulation experiment,and its result demonstrates that the new algorithm has greatly optimized the path of algorithm-level set and guaranteed fast running speed and high reliability.

Leakage Flux Adjustment and Flux Field Optimization for Coreless Axial Flux Permanent Magnet Synchronous Machine Based on U-shaped Iron

Wang Xiaoguang,Yin Hao,Liu Cheng,Li Xiaofeng,Zhang Guoguang,Liu Yi,Xu Wei 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.5

The rotor leakage flux will cause a lot of eddy current losses in the windings of coreless axial flux permanent magnet synchronous machine (CAFPMSM). This article presents a rotor leakage flux adjustment method for the CAFPMSM based on U-shaped iron, which can also achieve the optimization of the rotor flux field. The U-shaped iron can reduce the leakage flux crosses the winding and improve the spatial harmonic distribution of the air gap field at the same time. Firstly, the basic topology and its operating principle are investigated by using an equivalent magnetic circuit model. And then, the characteristics of the flux field distribution in the winding area are analyzed, and the parameters of the U-shaped iron on the leakage flux path regulation are elaborated and optimized by the three-dimensional finite-element method (3D FEM) analysis. Finally, the comprehensive experimental results show that the leakage flux path of the rotor passes through the U-shaped magnetically conductive block rather than through the windings, the total harmonic distortion (THD) of the air gap flux density waveform can be significantly decreased, and the THD of the back EMF and the eddy current losses are lower than before.

Screening of Candida utilis and medium optimization for co-production of S-adenosylmethionine and glutathione

Gongyuan Wei,Na Shao,Dahui Wang,Qianpeng Zhang,Xiaoguang Ge,Min Nie 한국화학공학회 2010 Korean Journal of Chemical Engineering Vol.27 No.6

An effective S-adenosylmethionine and glutathione enriching yeast mutant of Candida utilis CCTCC M 209298 was first screened from plates containing 0.5 g/L of DL-ethionine by complex mutagenesis with UV and γ-ray in this study. Medium components optimization for enhanced co-production of S-adenosylmethionine and glutathione by C. utilis CCTCC M 209298 was further carried out using response surface methodology. The significant factors influencing S-adenosylmethionine and glutathione co-production were selected by Plackett-Burman design as sucrose, KH2PO4 and L-methionine, and Box-Behnken design was applied for further optimization studies. Based on these approaches, the optimized concentrations on medium components for higher co-production of S-adenosylmethionine and glutathione were sucrose 35.4 g/L, (NH4)2SO4 10 g/L, KH2PO4 12.3 g/L, MgSO4·7H2O, 0.05 g/L, CaCl20.05 g/L and L-methionine 4.6 g/L. The medium optimization by response surface methodology led to a total production of 589.3 mg/L on S-adenosylmethionine and glutathione, which was 2.4-fold increased compared with the medium without optimization.

A novel strategy on the high-cell-density cultivation of Candida utilis for the enhanced production of glutathione

Gongyuan Wei,Min Nie,Na Shao,Xiaoguang Ge 한국화학공학회 2010 Korean Journal of Chemical Engineering Vol.27 No.4

Efficient glutathione production by high-cell-density cultivation of Candida utilis was investigated. A series of batch glutathione fermentations were carried out and the optimal initial glucose concentration was found to be about 26 g/L. Then, fed-batch fermentation under diverse feeding strategies was used to enhance glutathione production with a total glucose concentration of 150 g/L. Constant glucose feeding strategy cannot meet the requirement of cells at the late period of feeding, while exponential glucose feeding strategy cannot satisfy the needs of cells at the beginning of feeding. Based on the results above, a polynomial glucose feeding strategy was developed to provide enough glucose for cells along with the cultivation, under which both the cell and glutathione productivity were satisfactorily improved. Furthermore, fed-batch fermentation under this strategy with a total glucose concentration of 200 g/L was successfully performed, the dry cell weight and glutathione concentration reached 91.2 g/L and 825 mg/L, respectively.

Influence of the Billet Volume Distribution on Macro Deformation and Microstructure Response in Transitional Region of Ti-Alloy Multi-rib Component Under Isothermal Local Loading

Ke Wei,Qing Ma,Haibing Tang,Xiaoguang Fan,Jian Zhang 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.22 No.12

The folding, die underfilling, rib shifting and average grain size of primary equiaxed were investigated using five different unequal thickness billets in transitional region of Ti-alloy multi-rib component under isothermal local loading and compared with integral loading. In terms of the macro deformation, the results show that the material transfers from the second-loading zone into the first-loading zone and the die underfilling decreases with the initial volume of the first-loading zone increasing, which reduces the risk of folding and rib shifting. However, that folding and rib shifting did not appear during the integral loading. Nevertheless, when the initial volume of the first-loading zone reaches a certain value, the die underfilling is aggravated both in local and integral loading. With respect to the microstructure, as the initial volume of the first-loading zone increases, the average grain size is decreased after the first-loading step, but increased after the second-loading step with consideration of one single loading step, which lead to the grain size being barely influenced by different billet volume distribution under both loading steps.

Improved synthesis of isomaltooligosaccharides using immobilized a-glucosidase in organic–aqueous media

Jun Wang,Wei Li,Dandan Niu,Suren Singh,Fuping Lu,Xiaoguang Liu 한국식품과학회 2017 Food Science and Biotechnology Vol.26 No.3

a-Glucosidase was immobilized onto an epoxyactivated resin (Eupergit C) to catalyze maltose into isomaltooligosaccharides (IMO), and then the effects of organic–aqueous media on the enzymatic properties of immobilized a-glucosidase were examined. An immobilization efficiency of 79.61% was obtained under the condition of pH 6.0, ionic strength of 2.0 M, and 30 mg of protein/g of resin. The butyl acetate-aqueous biphasic system was found to significantly improve the catalytic activity of the immobilized enzyme and the yield of IMO. The highest yield of IMO (50.83%, w/w) was obtained at pH 4.5 and 55 C in a butyl acetate/buffer system (25:75, v/v). In addition, the immobilized enzyme particles were distributed into the organic phase after the completion of transglycosylation, which facilitates the separation and recycling use of the immobilized enzyme. Immobilized aglucosidase retains a robust reusability in this continuous operation model. The present findings are of potential in improving the IMO manufacturing process.

Structural analysis and testing of a miniature flexible joint under pressure and vector loading

Junxue Ren,Xiaoguang Zhang,Jingxian Yang,Chao Wang,Yu Liu,Wei Yang 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.9

The structural characteristics of a miniature tactical motor flexible joint subjected to pressure and vector loading were investigated usingfinite element analysis and bench test. Three-dimensional non-linear finite element analysis was conducted using ANSYS Code Version11.0. The axial deflection, vectoring torque, and stress distributions in elastomeric and reinforcement rings were presented. Thepredicted values were consistent with the test data. Results indicate that the axial compressive stiffness increased gradually and nonlinearlywith pressure, while the angular stiffness remained nearly constant in the vectoring angle range from 0° to 6°. Under pressureloading, the elastomeric shear stress was negative, high at both sides, and low at the center of the cross-section, while the reinforcementhoop stress was compressive at the inner radius and tensile at the outer radius. The compressive stress was also high. The flexible jointexhibited higher stress level with altered stress distribution when subjected to additional vector loading. Existing empirical formulas forreinforcement hoop compressive stress were determined to be not applicable to the miniature flexible joint, which significantly overestimatedthe stress caused by pressure and underestimated the stress caused by vectoring.

Cerebrospinal Fluid Leakage after Surgeries on the Thoracic Spine: A Review of 362 Cases

Panpan Hu,Miao Yu,Xiaoguang Liu,Zhongjun Liu,Liang Jiang, Feng Wei,Zhongqiang Chen 대한척추외과학회 2016 Asian Spine Journal Vol.10 No.3

Study Design: A retrospective clinical review. Purpose: To describe the incidence of cerebrospinal fluid leakage (CSFL) after thoracic decompression and examine the CSFL predisposing clinical factors. Overview of Literature: CSFL is a common complication following thoracic decompression but has not been sufficiently addressed in former studies. Methods: A cohort of 362 cases of thoracic decompression from February of 2005 to June of 2013 was examined. The case medical records were reviewed and the occurrence of CSFL and the related clinical parameters were noted. The incidence of CSFL for the entire cohort and each surgical approach were described. Besides, the relationship between CSFL and other clinical parameters were assessed, of which odds ratio values of all CSFL-associated parameters were calculated using multivariate logistic regression analysis. Results: The incidence of CSFL for the entire cohort was 32.3%. Different surgical approaches had different incidences of CSFL, and circumferential decompression had the highest incidence. Though many different clinical parameters were related to the occurrences of CSFL, being older than 52 years, having ossification of the posterior longitudinal ligament or having longer operative segments than 3 vertebrae were significant risk factors for CSFL (p <0.05). Besides, surgeries on the mid-thoracic spine had an increased risk of CSFL (p <0.05). Conclusions: From our analysis, CSFL was a common complication after thoracic decompression with the incidence of up to 32.3%. This study identified the predisposing clinical factors, and spinal surgeons should be aware of these risk factors to reduce its incidence.

Dynamic performance of 6.5 kV SiC MOSFET body diodes and anti‑parallel Schottky barrier diodes

Yujie Du,Xinling Tang,Xiaoguang Wei,Shuai Sun,Fei Yang,Zhibin Zhao 전력전자학회 2023 JOURNAL OF POWER ELECTRONICS Vol.23 No.6

For a silicon carbide (SiC) metal–oxide–semiconductor fi eld-eff ect transistor (MOSFET), both the body diode of the MOSFET and an anti-parallel diode can function as a freewheeling diode that carries reverse current. Selecting a suitable freewheeling method is particularly important to fully exploit the performance of high-voltage SiC MOSFET devices. In this study, based on the 6.5 kV SiC MOSFET and the Schottky barrier diode (SBD) developed by our research group, the dynamic characteristics of the MOSFET body diode, the SBD, and the parallel connection of the two are investigated. In addition, the influence of capacitive current on the dynamic characteristics is analyzed by establishing an equivalent circuit model. Test results show that when compared with the body diode, the SBD has an extremely low reverse recovery current, a lower capacitive current, and better reverse recovery temperature stability. Thus, the SBD is regarded as the most suitable freewheeling diode for the 6.5 kV SiC MOSFET. Finally, a package solution for the 6.5 kV SiC MOSFET and SBD is proposed.