An Efficient Optimization Design Framework for Low-Resistance Shape of Bionic Amphibious Robot

To realize the low-resistance shape optimization design of amphibious robots,an efficient optimization design framework is proposed to improve the geometric deformation flexibility and optimization efficiency.In the proposed framework,the free-form deformation parametric model of the flat slender body is established and an analytical calculation method for the height constraints is derived.CFD method is introduced to carry out the high-precision resistance calculation and a constrained Kriging-based optimization method is built to improve the optimization efficiency by circularly infilling the new sample points which satisfying the constraints.Finally,the shape of an amphibious robot example is optimized to get the low-resistance shape and the results demonstrate that the presented optimization design framework has the advantages of simplicity,flexibility and high efficiency.

Single Mode Simulation Calculation of Oscillating Buoy Wave Energy Converter with A Slider

This paper presents an oscillating slider wave energy device which is based on a seabed anchoring and uses eagle beak as the absorber.The self-compiled program uses the boundary element theory based on the simple Green’s function to solve the wave forces and hydrodynamic parameters.And the equation of motion,the oscillation of the float and the capture width ratio are obtained by the modal method.The influences of the shape of the eagle beak,the angle of the slider and the wave heading on the capture ability of the device are investigated.According to the calculation results and the wave resources in the sea area,the optimal shape of the eagle beak and external damping can be selected to maximize the wave energy capture capability.

Influence of explosive density on small scale internal blast experiments

To study the internal blast load, a lot of small scale internal blast experiments have been conducted. For those experiments, the influence of explosive density generally was not taken into account while it was simple to have slight density differences in application. To analyze the influence of explosive density on small scale internal blast experiments, the finite element code LS-DYNA was employed and the numerical model was established. The numerical model was validated against published experimental data and the result shows a good agreement. We found that that both the peak overpressure and impulse increase with the density of charge. Empirical equations were fitted using the calculation results to evaluate the influence of explosive density on the peak overpressures and impulses.

Inundation Calculation of the Coastal Narrow Plain Strip Impacted by Upstream Reservoir Flood Discharge in Rainy and Extreme Flood Conditions

In the context of current climate change, an abnormality of flooding is a common form of disaster in Vietnam. Hanh Stream reservoir has occurred great flood in 1986, 2010. In the future, the risk of flooding is possible to happen again. In view of management of the risk of natural disasters： large flooding situation downstream is one of the most dangerous risks for the reservoir. Due to downstream of Hanh Stream reservoir is a narrow coastal plains, quick infrastructure development, especially interwoven road and railway systems, so that flood drainage ability will be affected greatly. The consciousness of risks that may be occurred in the future in order to propose preventive measures and proactive response to minimize damages always is the requirement for all projects. The hydrodynamic calculation, flooding maps, emergency plan to prevent flooding downstream of Hanh Stream reservoir is also needed. The article is raised the issue of requirements to calculate coastal narrow delta strip flooding in the Central of Vietnam when impacted by the upstream reservoir of flood discharge in terms of extreme heavy rain and flooding and presented computational methods of Mike software package for case flooded plain of Cam Ranh Bay in downstream reservoirs of Hanh Stream, Khanh Hoa Province, Vietnam.

CALCULATION OF THE HYDRODYNAMIC CHARACTERISTICS OF A OWC WAVE ENERGY ABSORBER

This paper deals with the hydrodynamic response to waves of a 3-D OWC(oscillating water column)wave energy absorber with converging channel.The theoretical solutions are presented by means of three-dimensional GREEN function method.In the calculation,the flow field is divided into two subregions:an inside field and an outside one.In the outside field the solution is represented by oscillating sources distributed on the outer surface of the chamber of the absorber,while the solution of the inside field is expressed by Rakine source-distribution on the inner surface of the chamber.Both solutions are matched on the artificial interface.The calculated.values seem to agree reasonably well with experimental results.