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A multi-platform offshore wind farm is receiving the worldwide attention for the sake of maximizing the wind power capacity and the dynamic stability at sea. But, its wind power efficiency is inherently affected by the interference of wake disturbed by the rotating blades, so its layout should be appropriately designed to minimize such wake interference. In this context, the purpose of this paper is to introduce a layout optimization for multi-platform offshore wind farm consisted of 2.5MW spar-type floating wind turbines. The layout is characterized by the arrangement type of wind turbines, the spacing between wind turbines and the orientation of wind farm to the wind direction, but the current study is concerned with the spacing for a square-type wind farm oriented with the specific angle. The design variable and the objective function are defined by the platform length and the total material volume of the wind farm. The maximum torque loss and overlapping section area are taken as the constraints, and their meta-models expressed in terms of the design variable are approximated using the existing experimental data and the geometry interpretation of wake flow.

Functionally graded material (FGM) has a continuous and functional distribution of volume fractions of constituent particles, which leads to superior thermo-mechanical performance to classical laminated composite materials. Since the thermo-mechanical characteristics of an FGM depend on the volume fraction distribution, it is important to tailor appropriate volume fraction distribution that satisfies the desired performance requirements under given loading and boundary conditions. Even though numerical optimization technique may serve as an excellent material tailoring tool, the capacity of current manufacturing techniques of FGM may not yield the target volume fraction. To deal with uncertainty in the manufacturing process, a reliability-based design optimization (RBDO) for FGM composite is proposed. In RBDO, a finite number of volume fractions of homogenized FGM layers and material properties are considered as random variables, with statistical information such as mean, standard deviation, and statistical distributions. Design of experiments and response surface models are used to obtain explicit forms of thermal stresses for RBDO formulation. It is observed through the numerical experiment that the RBDO finds the optimized volume fraction distribution with high reliability, such that the graded layers do not fail in the presence of manufacturing uncertainty.

A dual ported frequency doubling cavity can be used to generate twin beams in the harmonic output with strong quantum correlations, even in the framework of a plane wave model. For a singly resonant cavity, the steady state solution of the fundamental field has to be self-consistent after propagating one round trip.

A new type diffractive spatial optical modulator has been developed for laser projection display. It has inherent advantages such as fast response time and high-performance light modulation characteristics. Also, it is suitable for embedded mobile projection display module because of its compact optical volume (les 20 cc) and low power consumption (les 2.0 W).

Radar stereo mapping or radargrammetry using high resolution spaceborne SAR data may be used to obtain terrain elevation maps. In the mapping context, SAR systems have an added advantage of being ranging devices. The geometric relationship of a terrain point with respect to the SAR is intrinsically encoded in the image by its position on the image. Indeed, the pixel coordinates specifies the distance r of the satellite from the imaged point p and the azimuth position of the satellite at that instant. The authors present some preliminary assessment on the quality of elevation data generated from a stereo-pair of Radarsat images. They first compare the range values of control points, whose ground coordinates are accurately known, with the calculated values. This gives a measure of the inherent inaccuracies in the satellite's position vector which are obtained from the orbit ephemeris information provided with the SAR data. They show that the the values obtained warrants some adjustments in the satellite's orbit. To this end, they model the two-body Keplerian orbit with a cubic polynomial. The parameters characterising the orbit are initially estimated from the ephemeris information. Using suitable ground control points these parameters are further refined using a least-squares adjustment technique. The coordinates of arbitrary points are then evaluated using the standard radargrammetric equations and compared with values obtained from a DEM of the test site.