Progress in laser technology has led to very compact but nevertheless powerful laser sources. In the visible and near infrared spectral region, lasers of any wavelength can be purchased. Continuous wave laser sources pose an especially serious threat to the human eye and electro-optical sensors due to their high proliferation and easy availability. The manifold of available wavelengths cannot b...

the strong ground motions recorded during the 2002 avaj earthquake have been used to estimates wave attenuation, qβ, and spectral decay parameter, κ, for the avaj region. qβ for shear wave is estimatedas a function of frequency in the range of 0.6- 18 hz. the results show that qβ increases with frequency in theform of qβ=62.7 f 0.9. our estimates are within the estimated range for different par...

This study determined some spectral characteristics and relationship between Landsat spectral reflectance and soil surface color in the arid region of Iran (Kashan). The study carried out in the kashan area that covers 90000 ha. Consisting of mountain, hills and flood plain. Enhanced Thematic Mapper (ETM+) data collected on July 2002 were used for this research. The color composite images produ...

this study determined some spectral characteristics and relationship between landsat spectral reflectance and soil surface color in the arid region of iran (kashan). the study carried out in the kashan area that covers 90000 ha. consisting of mountain, hills and flood plain. enhanced thematic mapper (etm+) data collected on july 2002 were used for this research. the color composite images produ...

amplitudes of seismic waves decrease with distance according to anelastic properties of the earth and geometrical spreading. the attenuation of ground-motion amplitudes in the frequency domain is an important problem in engineering seismology. it is of particular practical interest in the regions such as zagros (iran). the zagros fold- thrust belt, as a part of alpine- himalayan orogenic belt i...

Evanescent wave spectroscopy using thin optically transparent electrodes and multiple reflections allows unique observations of the electrochemical interphase since the region of solution sampled is typically 100 nm from the electrode in the visible spectral region. This technique is found to be highly sensitive to the presence of absorbing adsorbed species

Significantly enhanced absorption at the defect mode can be obtained at surfacenormal direction in a dielectric single-defect photonic-crystal-slab, with an absorption enhancement factor greater than 4,000. Complete absorption suppression within the photonic bandgap region can also be observed in defect-free photonic crystal cavities. High spectral selectivity and tunability is feasible with de...

We measured the ensemble-averaged spectral correlation functions and statistical distributions of spectral spacing and intensity for lasing modes in weakly scattering systems, and compared them to those of the amplified spontaneous-emission spikes. Their dramatic differences illustrate distinct physical mechanisms. Our numerical simulation revealed that even without reabsorption the number of p...