A CASE STUDY ON HARBOR OSCILLATIONS BY INFRAGRAVITY WAVES

In this study, the minimization of harbor oscillation using permeable breakwater was applied to the actual harbor and investigated a reduction effect by computer simulation in order to take into account the water quality problems and measures of harbor oscillation by infragravity waves at the same time. The study site is Mukho harbor located at east coast of Korea. The infragravity waves which obtained by analyzing the field data for five years focused on the distribution between wave periods of 40s and 70s and wave heights in less than 0.1m was 94percent of analyzing data. The target wave periods for minimization of harbor oscillation was 68s. The most effective method of minimization of harbor oscillation by infragravity waves was to install a detached permeable breakwater with transmission coefficient of 0.3 on the outside harbor and replace some area of the vertical wall with wave energy dissipating structure to achieve a reflectivity of 0.9 or less in a harbor. The reduction rate of amplitude shown in 27.4percent in this method.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/oDzrehaXlY8

A Microwave Three-Dimensional Imaging Method Based on Optimal Wave Spectrum Reconstruction

Limited by the Shannon–Nyquist sampling law, the number of antenna elements and echo signal data of the traditional microwave three-dimensional (3D) imaging system are extremely high. Compressed sensing imaging methods based on sparse representation of target scene can reduce the data sampling rate, but the dictionary matrix of these methods takes a lot of memory, and the imaging has poor quality for continuously distributed targets. For the above problems, a microwave 3D imaging method based on optimal wave spectrum reconstruction and optimization with target reflectance gradient is proposed in this paper. Based on the analysis of the spatial distribution characteristics of the target echo in the frequency domain, this method constructs an orthogonal projection reconstruction model for the wavefront to realize the optimal reconstruction of the target wave spectrum. Then, the inverse Fourier transform of the optimal target wave spectrum is optimized according to the law of the target reflectance gradient distribution. The proposed method has the advantages of less memory space and less computation time. What is more, the method has a better imaging quality for the continuously distributed target. The computer simulation experiment and microwave anechoic chamber measurement experiment verify the effectiveness of the proposed method.

Breakup of spatiotemporal pattern under electromagnetic radiation

Stable wave propagation is important for heart health, however, the electromagnetic radiation could affect normal signal propagation of heart, even make a sudden cardiac arrest. In this paper, the effect of electromagnetic radiation on the propagation of stable target wave generated by linear feedback control is studied in detail. It is confirmed that there are different transitions of electrical activities in cardiac tissue, which are transitions from target wave to spiral wave, some isolated islands of pattern waves coexisted, broken pattern and even the quiescent state, are generated when the electromagnetic field is imposed on the cardiac tissue in three ways. Furthermore, it is interesting to find there are different real affected regions, in which the electrical activities of nodes are destroyed, when the radiation signal is imposed on the cardiac tissue in different ways. It is also found the kinds of dynamical behaviors in the media are dependent on the real affected region. These results state that electromagnetic radiation could change the electrical activities, even destroy and suppress the wave propagation of wave source, and the ways of electromagnetic radiation imposed on the media are also important.

Numerical Manoeuvrable Tank on Wave Based Moving Domain

The maneuvering motion simulation of ship in waves needs large space, the simulation based static domain requires a large amount of mesh. On the contrary, the moving domain can reduce the grid amount and improve the simulation speed. This paper studies the establishment of numerical wave tank based moving domain. The wave-generation method of defining inlet boundary conditions is proposed. The level set method is used to solve the free surface. The URANS equation is solved by finite difference method and the projection algorithm. For the wave-generation method of defining inlet boundary conditions, the velocity inlet direction is always fixed because the direction of incident wave is always fixed. Specifically, the yaw should be turned off avoid the disturbance of wave in the y direction. Comparing the simulated wave with the target wave, the numerical results show that the simulated value is coincident with the theoretical value in the moving domain, and there are no obvious signs of dissipation over time. The established moving domain can produce a continuous and qualified wave, which provides a theoretical basis for the study of maneuvering simulation of ship in waves.