periodic noises are unwished and spurious signals that create repetitive pattern on images and decreased the visual quality. firstly, this paper investigates various methods for reducing the effects of the periodic noise in digital images. then an adaptive optimum notch filter is proposed. in the proposed method, the regions of noise frequencies are determined by analyzing the spectral of noisy...

One of the greatest challenges for the production of petroleum in deepwater is flow assurance. In fact, knowledge about the transient cool down behavior of the produced fluid is necessary to prevent the formation of hydrates and solid deposits during shutdown periods, which could result in a pipeline blockage and could result in large financial losses. In a typical subsea petroleum production s...

In chemical, biological, radiological, and nuclear protective clothing, a layer of activated carbon material in between two textile layers provides protection against hazardous gases. A cylinder in cross flow, sheathed by such material, is generally used to experimentally test the garment properties. This is, however, complicated and predictive models are needed. We present a computational flui...

We report here several particle membrane filters (8 × 8 mm) with circular, hexagonal and rectangular through holes. By varying hole dimensions from 6 to 12 μm, opening factors from 4 to 45 % are achieved. In order to improve the filter robustness, a composite silicon nitride/Parylene membrane technology is developed. More importantly, fluid dynamic performance of the filters is also studied by ...

in this paper, a novel decision based median (dbm) filter for enhancing mr images has been proposed. the method is based on eliminating impulse noise from mr images. a median-based method to remove impulse noise from digital mr images has been developed. each pixel is leveled from black to white like gray-level. the method is adjusted in order to decide whether the median operation can be appli...

In this paper, we proposed a novel structure for designing all optical filter based on photonic crystal structure. In designing the proposed filter, we simply employed a point defect localized between input and output waveguides as wavelength selecting part of the filter. The initial form of this filter is capable of selecting optical waves at =1560 nm, the transmission efficiency of the filte...

abstract in order to investigate the removal of copper, nickel, zinc and chromium from industrial waste water by a sand–soil–organic matter filter column, this experiment was conducted at a completely randomized design with sixteen treatments and four replications. p.v.c tubes (columns) with 66.5 cm height and 10 cm diameter were chosen and filled from down to top by coarse gravel (15 cm), sand...

Myocardial perfusion SPECT imaging with Tc99m-sestamibi is the most accurate non-invasive means of detecting coronary artery disease and assessing the severity of perfusion abnormalities in the patients with coronary stenosis. Though simple and straight forward the results produced by the technique is very much affected by the details being used. One of the main problems with the test, wh...

Multi-fluid models have recently been proposed as an approach to improving the representation of convection in weather and climate models. This is attractive framework it fundamentally dynamical, removing some assumptions mass-flux schemes which are invalid at current model resolutions. However, still not understood how best close multi-fluid equations for atmospheric convection. In this paper ...