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This paper presents one syntactic foam with excellent mechanical properties and prominent hydrostatic pressure performance for 11000 meters deep-sea. The properties of the syntactic foam are studied on the basis of relevant standards. The compressive strength, compressive modulus and shear strength of syntactic foams are about 100MPa, 1300MPa and 40MPa separately in atmosphere environment. The water...
Underwater absorption, scattering and turbulence processes will introduce attenuation and fading to light propagation and then degrade the performance of underwater wireless optical communications (UWOC). In this paper, we consider UWOC multiple-input single-output (MISO) links over which a single detector is illuminated by a uniform circular array (UCA) of an arbitrary number of light sources. We...
Due to the dramatic effect of scattering caused by underwater medium, blur commonly occurs in underwater images. Moreover, colors are frequently attenuated in underwater situations, in response to the effect that water selectively absorbs light of different wavelengths. Thus, this color loss becomes one of the key features of underwater images. Most present blur/sharpness evaluation algorithms, which...
In recent years, ultraviolet-visible spectroscopy has been widely used for measurements of water quality in seawater, because full spectrum contains large amounts of information. NO3 can be detected in 220–230 nm, and chemical oxygen demand (COD) and total organic carbon (TOC) can be detected in 280–290 nm. In visible spectrum, water color, turbidity and total suspended solids (TSS) can be measured...
With recent advances and interests in underwater wireless optical communications (UWOC), a proper understanding of optical propagation in underwater environment is more essential. In this paper, we study the channel model taking absorption, scattering and turbulence into account. Then we consider average (ergodic) channel capacity of UWOC links under weak turbulence. The fading coefficient of weak...
Underwater images are degraded mainly by light scattering and color distortion. Light scattering occurs because the light is reflected and deflected multiple times by the suspended particles in the water before reaching the camera. Color distortion is caused due to the absorption degrees vary according to the light wavelength. At last, the underwater images are dominated by a bluish tone. In this...
The characteristics of pigments in phytoplankton in surface water, e.g., composition, spectral absorption and specific absorption, were examined based on in situ data collected during a field cruise in Qinghai Lake in August 2003. This study identified two pigments of chlorophyll (Chl), two pigments of photosynthetic carotenoids (PSC), and seven pigments of photoprotective carotenoids (PPC) in the...
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