Study on the Breakwater Caisson as Oscillating Water Column Facility

The Oscillating Water Column(OWC) wave energy convertor with the advantage of its simple geometrical construction and excellent stability is widely employed.Recently,perforated breakwaters have been often used as they can effectively reduce the wave reflection from and wave forces acting on the structures.Considering the similarity between the compartment of perforated caisson and the air chamber of OWC wave energy convertor,a new perforated caisson of breakwater is designed in this paper.The ordinary caisson is modified by installing facilities similar to the air chamber of OWC converter,but here they are utilized to dissipate the wave energy inside the caisson.Such an arrangement improves the stability of the caisson and reduces the construction cost by using the compartment of perforated caisson like using an air chamber.This innovation has both academic significance and important engineering value.For a new type of caisson,reliability analysis of the structure is necessary.Linear potential flow theory is applied to calculate the horizontal wave force acting on the caisson.The calculated results are compared with experimental data,showing the feasibility of the method.The Importance Sampling Procedure(ISP) is used to analyse the reliability of this caisson breakwater.

Numerical Analysis of the Flow Field in a Sloshing Tank with a Horizontal Perforated Plate

Liquid sloshing is a type of free surface flow inside a partially filled water tank.Sloshing exerts a significant effect on the safety of liquid transport systems;in particular,it may cause large hydrodynamic loads when the frequency of the tank motion is close to the natural frequency of the tank.Perforated plates have recently been used to suppress the violent movement of liquids in a sloshing tank at resonant conditions.In this study,a numerical model based on OpenF OAM(Open Source Field Operation and Manipulation),an open source computed fluid dynamic code,is used to investigate resonant sloshing in a swaying tank with a submerged horizontal perforated plate.The numerical results of the free surface elevations are first verified using experimental data,and then the flow characteristics around the perforated plate and the fluid velocity distribution in the entire tank are examined using numerical examples.The results clearly show differences in sloshing motions under first-order and third-order resonant frequencies.This study provides a better understanding of the energy dissipation mechanism of a horizontal perforated plate in a swaying tank.

Modulating a Solar Parabolic Dish to Produce Boiled Water

A two-meter parabolic solar concentration dish has been modulated to produce boiled water over 100℃ for various purposes of central heating services. For an effective performance, the system required both continuous exposure of the dish to sunlight during the day time as well as to an electric control circuit （tracking system）. The amount of the potable water was dependent particularly on the accurate centering of the system which could increase upon preheating. This system has therefore been possible to heat up water at home via increasing the temperature in hot tank by both covering the hot water tank and isolating it from the surroundings using insulators. Applications of a successful parabolic solar concentration has also been designed to provide desalinated water for domestic usage which operates with temperatures higher than other types of the solar radiation for the future.

高级轿车维修

盛夏即将到来，在酪署中，汽车抛锚给我们带来的种种苦恼令人心有余悸，这当中，水箱开名优算是最让人头痛的一件事了，许多人有一种错觉，认为高档车设计制造精良，不可能出现水温高的问题，其实恰恰相反，现代轿车发展的方向是小排量，大功率，并且，越是紧凑合的发动机，温度水平越高，因此，某一个小环节上出问题就可能导致整个系统的故障。