Poly(vinyl alcohol)/Hydroxylapatite (PVA/HA) composite hydrogel was prepared with poly(vinyl alcohol) and hydroxylapatite
as raw materials, using the method of repeated freezing and thawing. The morphologies of PVA/HA composite hydrogel were observed
by means of high-accuracy 3D profiler and scanning electron microscope (SEM). The compressive elastic modulus and the stress
relaxation characteristics of PVA/HA composite hydrogel were measured using the flat-head cylinder indenter. The friction
and wear tests between PVA/HA composite hydrogel and bovine knee articular cartilage were performed on the micro-tribometer.
The worn morphologies of PVA/HA composite hydrogel were observed with environmental scanning electron microscope (ESEM). The
results showed that PVA/HA composite hydrogel has the cross-link network microstructure which is similar to that of the natural
bovine knee articular cartilages. With the increase of freezing-thawing cycles and the HA content, the degree of cross-link
and the crystallization of PVA/HA composite hydrogel both increase, the elastic modulus increases evidently, the rate of stress
relaxation is improved and the value of balance stress decreases. The friction coefficient decreases with the increase of
the freezing-thawing cycles and the HA content. The more the freezing-thawing cycles are, the earlier the friction coefficient
reaches the stable balance value. The friction deformation depth between PVA/HA composite hydrogel and bovine knee articular
cartilage is inversely proportional to freezing-thawing cycles and the HA content. The main wear mechanisms of PVA/HA composite
hydrogel are plastic flowing and adhesive flaking. The wear severity degree decreases with the increase of freezing-thawing
cycles and the HA content.
Supported by Key Program of the National Natural Science Foundation of China (Grant No. 50535050), Program for New Century
Excellent Talents in University (Grant No. NCET-06-0479) and Natural Science Foundation of Jiangsu Province (Grant No. BK2005403) 相似文献
Cu–dinitro–diamino phthalocyanine was synthesized and converted to the diazonium salt. Polyacrylamide bonded CuPc(NO2)2 [PAA–CuPc(NO2)2] (I) was synthesized by hot polymerization of acrylamide and this diazonium salt. Polymer(I) is water soluble and contains about 7 mol % CuPc(NO2)2 rings, which are covalently bonded to PAA. Polymer(I) shows good photoconductivity, which is much better than that of the corresponding phthalocyanine monomers. By doping with iodine (I2), the photosensitivity of polymer(I) is increased, which through fluorescence analysis is explained by the fact that a charge–transfer complex (CTC) of polymer(I) with I2 is formed. The influence of interface layer (IFL) and charge–transportation material (CTM) on the photoconductivity of polymer(I) were also studied. 相似文献
Information Systems Frontiers - System logs that trace system states and record valuable events comprise a significant component of any computer system in our daily life. Each log contains... 相似文献
Palmprint recognition and palm vein recognition are two emerging biometrics technologies. In the past two decades, many traditional methods have been proposed for palmprint recognition and palm vein recognition, and have achieved impressive results. However, the research on deep learning-based palmprint recognition and palm vein recognition is still very preliminary. In this paper, in order to investigate the problem of deep learning based 2D and 3D palmprint recognition and palm vein recognition in-depth, we conduct performance evaluation of seventeen representative and classic convolutional neural networks (CNNs) on one 3D palmprint database, five 2D palmprint databases and two palm vein databases. A lot of experiments have been carried out in the conditions of different network structures, different learning rates, and different numbers of network layers. We have also conducted experiments on both separate data mode and mixed data mode. Experimental results show that these classic CNNs can achieve promising recognition results, and the recognition performance of recently proposed CNNs is better. Particularly, among classic CNNs, one of the recently proposed classic CNNs, i.e., EfficientNet achieves the best recognition accuracy. However, the recognition performance of classic CNNs is still slightly worse than that of some traditional recognition methods.
International Journal of Control, Automation and Systems - An underwater gliding snake-like robot (UGSR) combines the advantages of an underwater glider (UG) and an underwater snake-like robot... 相似文献
An appropriate acquisition configuration in terms of signal quality can optimize the acquisition performance. In view of this, a new approach of acquisition assisted by the control voltage of automatic gain control(AGC) is proposed. This approach judges the signal power according to the AGC control voltage and switches the working modes correspondingly and adaptively. Non-coherent accumulation times and the detection threshold are reconfigured according to the working mode. Theoretical derivation and verification by simulation in typical situations are provided, and the algorithm is shown to be superior in terms of the mean acquisition time, especially in strong signal scenarios compared with the conventional algorithm. 相似文献
Based on some assumptions, the dynamic analysis model of anchorage system is established. The dynamic governing equation is expressed as finite difference format and programmed by using MATLAB language. Compared with theoretical method, the finite difference method has been verified to be feasible by a case study. It is found that under seismic loading, the dynamic response of anchorage system is synchronously fluctuated with the seismic vibration. The change of displacement amplitude of material points is slight, and comparatively speaking, the displacement amplitude of the outside point is a little larger than that of the inside point, which shows amplification effect of surface. While the axial force amplitude transforms considerably from the inside to the outside. It increases first and reaches the peak value in the intersection between the anchoring section and free section, then decreases slowly in the free section. When considering damping effect of anchorage system, the finite difference method can reflect the time attenuation characteristic better, and the calculating result would be safer and more reasonable than the dynamic steady-state theoretical method. What is more, the finite difference method can be applied to the dynamic response analysis of harmonic and seismic random vibration for all kinds of anchor, and hence has a broad application prospect. 相似文献