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Type synthesis of 3T2R decoupled hybrid mechanisms with large bearing capacity
Sen Wang,Shihua Li,Haoran Li,Yajie Zhou,Yongjie Wang,Xinyu Wang 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.4
This paper proposes a new synthesis method of three translational and two rotational (3T2R) decoupled hybrid mechanism with large bearing capacity, based on the screw theory and the atlas method. According to the degree of freedom and decoupled characteristics of the 3T and 2R mechanisms, the decoupled conditions for the 3T and 2R parallel mechanisms are proposed. The optimal conditions for the motion/force transmission performance of the 3T decoupled parallel mechanisms with redundant actuation is presented. A redundant actuated limb construction method is proposed to improve the load capacity of the hybrid mechanism. Following the design steps of the fully decoupled hybrid mechanism, 3T2R hybrid mechanisms with large load capacity are obtained. Kinematics and statics analysis verify the correctness of the proposed synthesis method. The mechanism synthesized by this method has a good application prospect in large load occasion.
GENERALIZED WEYL'S THEOREM FOR FUNCTIONS OF OPERATORS AND COMPACT PERTURBATIONS
Zhou, Ting Ting,Li, Chun Guang,Zhu, Sen Korean Mathematical Society 2012 대한수학회보 Vol.49 No.5
Let $\mathcal{H}$ be a complex separable infinite dimensional Hilbert space. In this paper, a necessary and sufficient condition is given for an operator T on $\mathcal{H}$ to satisfy that $f(T)$ obeys generalized Weyl's theorem for each function $f$ analytic on some neighborhood of ${\sigma}(T)$. Also we investigate the stability of generalized Weyl's theorem under (small) compact perturbations.
Preparation and antifouling performance of PVDF-DCOIT composite hollow fiber membranes
Sen Qiao,Hongjie Cao,Yue Yang,Ruofei Jin,Jiti Zhou 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.3
Membrane fouling is the main bottleneck that hinders the applications of membrane bioreactors (MBRs). 4,5-Dichloro-2-n-octyl-4-isothiazolin-3-one (DCOIT), as an environmentally-acceptable antifouling biocide, was mixed with Polyvinylidene fluoride (PVDF) to fabricate hollow fiber membrane via non-solvent induced phase separation (NIPS), which was able to effectively improve the antifouling performance of the membranes in this work. Overall research of the prepared membrane revealed that membranes with 3 wt% DCOIT exhibited the optimum antifouling performance. With the addition of DCOIT, hydrophilicity and pure water flux of 3 wt% DCOIT membranes maintained remarkable improvement by 22.9% and 64.6% than that of membranes without DCOIT. Meanwhile, the surface morphologies of 3wt% DCOIT membranes were smoother than the control group in terms of SEM and AFM images, which was beneficial to alleviate membrane fouling. In antifouling experiments, the flux variation rate of membranes with 3 wt% DCOIT filtrated in bull serum albumin, sodium alginate and humic acid solution were 81.42%, 54.25%, 50.5%, while membrane without DCOIT were 64.6%, 24.72% and 29%, respectively. Similar results were obtained by filtrating anaerobic sludge for 24 h. The flux variations of 3 wt% DCOIT membranes were 59.4%, 47.8% and 46.0%, respectively in three stages. However, the flux variations of membranes without DCOIT were 44.8%, 36.7% and 19.8%, respectively, which showed better antifouling ability and higher flux recovery efficiency. The novel membranes would provide some theoretical basis and technical support for the rational combinations in elevating the overall antifouling properties of membranes.
A Novel Video Image Text Detection Method
( Lin Zhou ),( Xijian Ping ),( Haolin Gao ),( Sen Xu ) 한국인터넷정보학회 2012 KSII Transactions on Internet and Information Syst Vol.6 No.4
A novel and universal method of video image text detection is proposed. A coarse-to-fine text detection method is implemented. Firstly, the spectral clustering (SC) method is adopted to coarsely detect text regions based on the stationary wavelet transform (SWT). In order to make full use of the information, multi-parameters kernel function which combining the features similarity information and spatial adjacency information is employed in the SC method. Secondly, 28 dimension classifying features are proposed and support vector machine (SVM) is implemented to classify text regions with non-text regions. Experimental results on video images show the encouraging performance of the proposed algorithm and classifying features.
A Novel Video Image Text Detection Method
( Lin Zhou ),( Xijian Ping ),( Haolin Gao ),( Sen Xu ) 한국인터넷정보학회 2012 KSII Transactions on Internet and Information Syst Vol.6 No.3
A novel and universal method of video image text detection is proposed. A coarse-to-fine text detection method is implemented. Firstly, the spectral clustering (SC) method is adopted to coarsely detect text regions based on the stationary wavelet transform (SWT). In order to make full use of the information, multi-parameters kernel function which combining the features similarity information and spatial adjacency information is employed in the SC method. Secondly, 28 dimension classifying features are proposed and support vector machine (SVM) is implemented to classify text regions with non-text regions. Experimental results on video images show the encouraging performance of the proposed algorithm and classifying features.
Nondestructive Surface Threshold Definition for Remanufacturing Disassembly of Interference Fit
Dan Zhou,Sen Lan,Xin Gao,Haihong Huang,Guang-Fu Liu 한국정밀공학회 2018 International Journal of Precision Engineering and Vol.19 No.11
The disassembly of interference fit is a difficult process for remanufacturing engineering, which frequently causes multiple types of friction damage, such as scratches, furrow, and adhesion on the surface of parts. The form and size of surface damage directly affect the cost of remanufacturing repair. If the damage is less than a threshold, the part can be directly used for assembly without repairing. This condition represents a nondestructive disassembly, which is the goal of remanufacturing disassembly for interference fit. In this study, varying degrees of disassembly surface damage of interference fit are obtained by experiment and detected by TRIMOS-CL3 3D surface profilometer. Six surface evaluation parameters Sv, Sp, Sq, Str, Vmp, and Sa, are selected from ISO 25178 as indexes for entropy analysis to evaluate the damage comprehensively. According to the interface state, a comprehensive evaluation threshold of nondestructive disassembly is proposed. The rationality of the threshold is verified by the load-carrying capacity experiment of the interference fit.
Rong Wu,Sen Zhou,Minglong Liu,Haiqian An,Zhe Wang,Tianxi Liu 연세대학교의과대학 2022 Yonsei medical journal Vol.63 No.3
Purpose: Vascular calcification (VC) is a common complication of end-stage renal disease (ESRD). This study aimed to examinechanges in the expression of miR-21-5p in ESRD patients with VC and to explore its clinical value in predicting the occurrenceand progression of uremic VC. Materials and Methods: 120 ESRD patients were divided into patients without VC group (n=38) and patients with VC group(n=82). All patients were followed up for 2 years to evaluate VC progression. qRT-PCR was used to detect serum miR-21-5p levels. Receiver operating characteristic curves were constructed to assess diagnostic value. Kaplan-Meier and log-rank methods wereutilized to calculate associations between VC progression and risk factors. Results: Serum miR-21-5p levels were significantly higher in ESRD patients with VC than in those without VC and increased progressivelywith increasing disease severity. Serum miR-21-5p levels were able to distinguish patients with VC from those withoutVC, with an area under the curve value of 0.883, a sensitivity of 81.7%, and a specificity of 84.2%. After 2 years of follow-up, miR-21-5p expression had increased in patients with worse VC severity, compared with those with stable VC severity. Patients withhigh miR-21-5p levels were more likely to develop more severe VC, indicating an association between miR-21-5p and VC progression(log-rank p=0.002). Multivariable Cox regression analysis suggested that serum miR-21-5p is an independent predictive factorof VC progression in ESRD patients (hazard ratio=2.064, 95% confidence interval=1.225–3.478, p=0.006). Conclusion: miR-21-5p is overexpressed in the serum of ESRD patients with VC. Our results suggest that overexpression of miR-21-5p is closely associated with VC progression.