The refraction of a localized narrow beam is significantly different from that of a plane wave. As the beam width decreases to be in the order of the wavelength, the refraction behavior deviates noticeably from Snel’s law, and when the width of a light beam is smaller than about one fifth of the wavelength of the incident light, finite-difference time-domain simulations demonstrate that refract...

ABSTRACT A likelihood ratio test is proposed for moving target detection in an ultra wide frequency band and wide antenna beam (wide band) SAR system. The developed method combines time domain fast backprojection SAR processing methods with moving target detection. It saves computational load when all relative speeds can be tested using the same clutter suppressed sub-aperture beams. The propos...

An experiment has been carried out at the Brookhaven Accelerator Test Facility to investigate the effect of a surface-roughness wakefield in narrow beam tubes with artificially created bumps. The measurements show that the synchronous modes decay significantly due to the randomization of the roughness pattern. It is pointed out that this decay mechanism has not been investigated in the previous...

Aged oxide-defined narrow-stripe lasers sometimes exhibit beam narrowing in both the near-field and far-field light distributions, accompanied by the development of sustained pulsations. The beam narrowing is found to correlate with the presence of a darkened area under the stripe viewed by cathodoluminescence imaging. We propose an explanation based on a thermal waveguiding effect resulting fr...

Abstract We propose and analyze a scheme to generate enhanced narrow-band terahertz (THz) radiation through down-conversion of the frequency of optical lasers using laser-modulated electron beams. In the scheme the electron beam is first energy modulated by two lasers with wave numbers k1 and k2, respectively. After passing through a dispersion section, the energy modulation is converted to den...

breeding programs strategies depends on genetical mechanism of selection traits. in the present research, generation mean analysis with joint scaling test was performed to determine the gene action. f1, f2 and f3 generations, derived from roushan and kavir cross along with their parents were sown in a partial lattice design with two replications under stress condition at the research field of s...

The substorm-related acceleration and flux increases of energetic oxygen ions are studied on the basis of test particle orbits in the fields obtained from an MHD simulation of plasmoid formation and ejection and the collapse (dipolarization) of the inner tail. The simulated fluxes show large anisotropies and nongyrotropic effects, phase bunching, and spatially and temporally localized beams. Th...

An inherent element of research and applications in photonics is a beam of light. In magnonics, which is the magnetic counterpart of photonics, where spin waves are used instead of electromagnetic waves to transmit and process information, the lack of a beam source limits exploration. Here, we present an approach enabling generation of narrow spin wave beams in thin homogeneous nanosized ferrom...