Study on ship's stability loss in surf-riding based on CFD
Based on Computational Fluid Dynamics, ship's righting arms of different heeling angles were calculated to study ship's stability loss in following sea. First, based on the wave-generation method of defining inlet boundary conditions, the numerical wave tank was constructed for ship's movement in surf-riding. Second, one slender ship's flow filed in calm water was numerically simulated, and the righting arms of different heeling angles were calculated. Third, the slender ship was set to navigate in surf-riding with wave crest at the midship section, and the flow field was simulated to get the righting arms of different heeling angles. The simulation results indicate that the righting arm in calm water show good agreement with experiment data; the stability loss is more serious when the wave amplitude is bigger; and ship wave's effect cannot be neglected in calculating ship's stability loss in surf-riding when ship speed is high.
NONLINEAR PREDICTION OF VERTICAL MOTIONS OF A FISHING VESSEL IN HEAD SEA
Several years ago the authors developed a practical method for calculating vertical motions and wave loads of a high-speed craft which travels in regular head sea, and verified its validity by comparing the computed motions and wave loads with the results of model tests. In order to clarify further its validity, the method is applied herein to compute the vertical modions of a fishing vessel, and the computed motions are compared with the results of experiments conducted by Bales and others at the David W. Taylor Naval Ship Research and Development Center (DTNSRDC). Also, the vertical motions and ship-to-wave relative motions predicted by the method are compared with the numerical results of conventional linear strip theory computations performed at DTNSRDC. As a result, it is found that the present method, which in principle is based on the conventional Ordinary Strip Method synthesis but modified to be able to evaluate nonlinear hydrodynamic impact forces as well as dynamic lift in waves, can be applied to estimate vertical motions and ship-to-wave relative motions of fishing vessels travelling in head sea with enough accuracy for practical use.
An injectable and thermosensitive hydrogel: Promoting periodontal regeneration by controlled-release of aspirin and erythropoietin.
Periodontitis is an inflammatory disease induced by complex interactions between host immune system and plaque microorganism. Alveolar bone resorption caused by periodontitis is considered to be one of the main reasons for tooth loss in adults. To terminate the alveolar bone resorption, simultaneous anti-inflammation and periodontium regeneration is required, which has not appeared in the existing methods. In this study, chitosan (CS), β-sodium glycerophosphate (β-GP), and gelatin were used to prepare an injectable and thermosensitive hydrogel, which could continuously release aspirin and erythropoietin (EPO) to exert pharmacological effects of anti-inflammation and tissue regeneration, respectively. The releasing profile showed that aspirin and EPO could be continuously released from the hydrogels, which exhibited no toxicity both in vitro and in vivo, for at least 21 days. Immunohistochemistry staining and micro-CT analyses indicated that administration of CS/β-GP/gelatin hydrogels loaded with aspirin/EPO could terminate the inflammation and recover the height of the alveolar bone, which is further confirmed by histological observations. Our results suggested that CS/β-GP/gelatin hydrogels are easily prepared as drug-loading vectors with excellent biocompatibility, and the CS/β-GP/gelatin hydrogels loaded with aspirin/EPO are quite effective in anti-inflammation and periodontium regeneration, which provides a great potential candidate for periodontitis treatment in the dental clinic. Statement of Significance To terminate the alveolar bone resorption caused by periodontitis, simultaneous anti-inflammation and periodontium regeneration is required, which has not appeared in the existing methods. Here, (1) the chitosan (CS)/β-sodium glycerophosphate/gelatin hydrogels loaded with aspirin/erythropoietin (EPO) can form at body temperature in 5 min with excellent biocompatibility in vitro and in vivo; (2) The faster release of aspirin than EPO in the early stage is beneficial for anti-inflammation and provides a microenvironment for ensuring the regeneration function of EPO in the following step. In vivo experiments revealed that the hydrogels are effective in the control of inflammation and regeneration of the periodontium. These results indicate that our synthesized hydrogels have a great potential in the future clinical application.