Antenna array has been used in many fields such as radar, sonar, electron reconnaissance and seismic data processing. The direction-of-arrival(DOA-) estimation of signals impinging on an array of sensors is a fundamental problem in array processing [1–5]. Angle estimation and frequency estimation [6, 7] are two key problems in the signal processing field. The problem of joint DOA and frequency ...

In order to reconstruct the viewable surface of an object completely, multiple views of the same object have to be used and integrated into a common coordinate system. One of the major problems of the 3d surface reconstruction using a turntable, is the varying resolution in the direction to the camera, due to the varying distance of object points to the rotational axis of the turntable. To guar...

Surface roughness amplifies the water-repellency of hydrophobic materials. If the roughness geometry is, on average, isotropic then the shape of a sessile drop is almost spherical and the apparent contact angle of the drop on the rough surface is nearly uniform along the contact line. If the roughness geometry is not isotropic, e.g., parallel grooves, then the apparent contact angle is no longe...

in the traditional hole drilling method the in-plane stresses are studied in detail and the interlaminar stresses are not taken seriously. the interlaminar stresses on the free edge of composite materials are important and can cause matrix cracking and delamination. inserting holes in composite laminates causes free edges and it can induce interlaminar shear and normal stresses. in this researc...