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Hangzhou, China

Liu P.,Shanghai Shanshan Technology Co. | Liu P.,Zhejinag University | Wang N.,Shanghai Ninth Peoples Hospital | Hao Y.,Shanghai Ninth Peoples Hospital | And 4 more authors.
Medical Principles and Practice | Year: 2014

Objective: To investigate the effect of entangled titanium fibre balls (ETFBs) combined with nano strontium hydroxyapatite (nano-Sr-HAP) on the repair of bone defects in vivo. Materials and Methods: Twenty-four 6-month-old, specific pathogen-free, male Sprague-Dawley rats were used. Drill defects were created in bilateral femoral condyles. ETFBs combined with nano-Sr-HAP were selected randomly from 72 samples and implanted into the femoral bone defects of left legs, which served as the experimental group, while ETFBs without nano-Sr-HAP were implanted into right legs for comparison. The bone defects on both sides were X-rayed. The anteroposterior positions and histological procedures and evaluations of each sample were performed at 1, 2, 4 and 8 weeks post-surgery. Results: Histological results showed that the ETBs allowed new bone to grow within their structure. Additionally, an increase in new bone was seen on the nano-Sr-HAP side compared to the control side. The results of histomorphometric analysis confirmed that the new bone formation on the left side gradually increased with time. There was a statistical increase in new bone at 2, 4 and 8 weeks, and the differences between the two sides were statistically significant at weeks 4 and 8 (p < 0.05 for all comparisons). Conclusion: The results showed that ETFBs possess a unique 3-dimensional interconnective porous structure and have excellent biocompatibility, cell affinity and osteoconductivity, which makes them useful as scaffold materials for repairing bone defects. On the other hand, nano-Sr-HAP improved the bone defect-repairing capacity of the ETFBs, which showed osteoinductive properties. © 2014 S. Karger AG, Basel. Source


Qu W.-W.,Zhejinag University | Shi X.,Zhejinag University | Dong H.-Y.,Zhejinag University | Feng P.-J.,Hanzhong Aircraft Company | And 2 more authors.
Zhejiang Daxue Xuebao (Gongxue Ban)/Journal of Zhejiang University (Engineering Science) | Year: 2014

Kinematic modeling and simulation of percussive impact riveting are presented to improve the quality of riveting process. Kinematic model of rivet gun is setup to determine the output speed and frequency of hammer under different input pneumatic pressure, ranging from 0.2 MPa to 0.6 MPa; Process of percussive impact riveting is simulated in ABAQUS, and by setting different speed of hammer (acquired in the kinematic model), the corresponding riveting time is acquired when the driven rivet head dimension is acceptable. Finally, riveting tests are carried out for model validation donghuiyue, Deviation between the simulation and experimental results is under 15%, which shows the effectiveness of the proposed method. All above end up with an conclusion that input pressure and riveting time has a great influence on riveting process. Source


Tu Z.-B.,Zhejinag University | Huang M.-F.,Zhejinag University | Lou W.-J.,Zhejinag University
Zhejiang Daxue Xuebao (Gongxue Ban)/Journal of Zhejiang University (Engineering Science) | Year: 2016

To estimate the extreme load effects on a bridge tower-basement system under the joint actions of wind and wave precisely, an improved approach based on statistical extrapolation aiming to calculate the extreme load effects under the joint actions of several environmental variables was proposed. In this approach, the distribution function of peak load effects was extrapolated by the joint distribution property of environmental variables and dynamic properties of structures, and the extreme load effect was taken as the peak load effect associated with a given exceedance probability. The extreme load effects on a bridge tower-basement system due to the joint actions of wind and wave were computed by the proposed method, and the coupling effects of wind and wave were studied numerically. It is demonstrated that the proposed method is effective and adequate to predict the extreme load effects on structures under the joint stochastic actions of wind and wave for structural design purpose. © 2016, Zhejiang University Press. All right reserved. Source


Bi Y.-B.,Zhejinag University | Li Y.-C.,Zhejinag University | Gu J.-W.,Zhejinag University | Guo Y.-J.,Zhejinag University | And 3 more authors.
Zhejiang Daxue Xuebao (Gongxue Ban)/Journal of Zhejiang University (Engineering Science) | Year: 2014

A robotic automatic drilling system which integrates the technology of laser measurement, computer control, off-line programming and robotics is established in order to realize automatic flexible drilling with high efficiency and good quality in the field of aircraft assembly. In drilling process, the normal vector of the aircraft surface can be obtained through the 3D model, but there is deviation between the 3D model and the real surface of part. To improve the holes' quality, a surface-normal adjustment system based on four laser displacement sensors is developed. The sensor' origin point position and laser direction are obtained by calibration. Then with the measured values of laser displacement sensors, the surface-normal vector is calculated. The attitude of the robot is changed to make sure the drilling direction is close to the surface-normal direction. The drilling test results show that the system can increase the drilling efficiency and assembly quality of the aircraft components immensely. The efficiency of drilling can achieve 6 holes per minute, and the surface-normal accuracy is better than 0.5°. Source

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