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Flow Expansion and Deflection Downstream of a Symmetric Multi-Gate Sluice Structure
Yuejun Chen,James Yang,Jianzhong Yu,Zongfu Fu,Qingsheng Chen 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.2
A sluice structure with multiple gates is often followed by an enlarging channel downstream. Experiments are conducted for different enlargement ratios in cross-section and Froude numbers at the gates. A large-scale PIV system is adopted to capture the surface flow field for examination of the flow features. The study shows that, despite the centrally placed sluice structure with symmetric outflow, a hydraulic jump occurs and the main flow downstream exhibits, in terms of expansion and deflection, a high degree of asymmetry and formation of large circulation zones. The degree of deflection increases significantly along the longitudinal direction for all the enlargement ratios except the smallest. The toe of the hydraulic jump is controlled at the upper edge of the sloping surface downstream of the gates. In light of outflow width, Froude number and enlargement ratio, the flow is classified into three regions. Immediately downstream, the effect of outflow width gradually decreases with increasing Froude number. Further downstream, the degree of deflection augments with increasing enlargement ratio, with circulation zones. At a given cross-section, the degree of expansion is positively related to the enlargement ratio. The study is expected to provide guidance for examination of similar issues of flow pattern and erosion protection design.
Manifold-ranking Based Image Retrieval Using Natural Neighbor
Qingsheng Zhu,Zhi Chen,Cheng Zhang 보안공학연구지원센터 2016 International Journal of Database Theory and Appli Vol.9 No.8
The manifold-ranking based method is widely used in semi-supervised learning, and its performance is closely related to the structure of the constructed graph. In this paper, we propose a novel graph structure named natural neighbor graph and an algorithm to construct it. We apply the new graph structure into the framework of manifold-ranking based image retrieval. The greatest superiority over k-NN based method is that the free parameter k need not to be explicitly specified any more. We have shown that the manifold ranking algorithm based on our proposed graph structure performs better than k-NN graph. Experiments demonstrate that the proposed algorithm outperforms the state-of-the-art algorithms.
Field Load Testing Study of Vertical Bearing Behavior of a Large Diameter Belled Cast-in-Place Pile
Guangyun Gao,Meng Gao,Qingsheng Chen,Jun Yang 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.5
To investigate the vertical bearing behavior of manually excavated large diameter belled concrete piles (LDBCPs), field loading tests were performed on a total of 16 LDBCPs, ranging from 0.8 to 3.5 m in base diameter from 6.1 to 18.0 m in embedment length. The end bearing stratum is sand and gravel. The influence of pile dimensions (i.e., size of enlarged base D, embedment length L, and length-to-diameter ratio L/D) on the vertical bearing behavior of a belled pile is presented and discussed. Comparison is also made of the vertical bearing behavior of a belled pile and of a conventional straight pile under otherwise similar conditions. The results indicate that: 1) The vertical bearing capacity of a belled pile is significantly greater than that of a conventional straight pile provided the debris at the bottom of a belled pile is properly removed; 2) over 65% of the vertical bearing capacity for a belled pile is attributed to the tip resistance (Qe); 3) compared to the contribution of pile length L, increasing enlarged base D is a more effective way to increase the vertical ultimate bearing capacity of a belled pile (Qu); 4) the optimum length-to-enlarged base ratio (L/D) for belled piles to achieve maximum vertical bearing capacity is around 3.2.
Hand-eye Calibration of Dual Mechanical Arms of Explosive Ordnance Disposal Robot
Jianfeng Jiang,Xiao Luo,Qingsheng Luo,Lijun Qiao,Yuhan Chen 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.7
The explosive ordnance disposal (EOD) robot works in a special environment, which requires dual robotic arms to work together for removing the bomb. Therefore, the coordinate calibration accuracy is the prerequisite for realizing the coordinated movement and visual positioning of the dual robotic arms. A basic problem encountered in the collaborative work of the dual robotic arms system is to determine the homogeneous transformation matrix of the frame, including: hand-eye, base-base, and gripper-camera. We formulate the hand-eye calibration problem of the dual robotic arm as the matrix equation AXB = YCZD. 1) An improved closed solution for singlerobotic arm hand-eye calibration is proposed. This closed solution of the single-robotic arm is used to quickly obtain the initial estimate of the iterative method to improve the efficiency and accuracy of the iteration. 2) The iterative solution of dual robotic arms hand-eye calibration based on the rotation vector is proposed. 3) In addition, a motion trajectory plan of the mechanical gripper is proposed to guide the operator to select the appropriate robot posture during the calibration process. In order to show the feasibility and superiority of the proposed method, a real EOD robot experiment is carried out. The comparison results from experiments show that the proposed simultaneous calibration method has higher accuracy and efficiency.
Haiyan Wang,Fenglan Zhang,Jin Cao,Qingsheng Zhang,Zhirong Chen 한국식품과학회 2013 Food Science and Biotechnology Vol.22 No.2
Proteolysis of grass carp sarcoplasmic, myofibrillar,and stromal proteins by 5 commercial proteases were studied. Sarcoplasmic and myofibrillar protein could be well hydrolyzed by Alcalase 2.4 L to reach high protein recoveries (PR) (71.86±2.46 and 80.77±3.05%, respectively),while the maximum PR for stromal protein was only 42.83±2.84%. However, stromal hydrolysates, containing mostly 6-10 kDa fraction, exhibited higher ·OH scavenging activities due to its high content of antioxidant-assisting amino acids. Alcalase 2.4 L and pancreatin 6.0, which produced hydrolysates with relative high degree of hydrolysis (DH), were used for further hydrolysis of whole grass carp protein with the assistance of response surface methodology (RSM). The results showed that serine proteases (Alcalase 2.4 L and pancreatin 6.0) could produce sarcoplasmic, myofibrillar, or stromal hydrolysates with relatively high PR, DH, and strong ·OH scavenging activity, which may be used to prepare antioxidant hydrolysates from grass carp.