Ultraviolet waves, because of their short wavelength, have a high energy and considerable damaging effects on surfaces. Protection against ultraviolet radiations is one of the finishing treatments done on surfaces exposed to sunlight. The importance of this issue in relation to human health, due to complications such as skin burns and cancer, is doubled. Up t...

In this paper, the optical properties of one dimensional fractal structures are investigated. We consider six typical fractal photonic structures: the symmetric dual cantor-like fractal structure, the asymmetric dual cantor-like fractal structure, the single cantor-like fractal structure, the symmetric dual golden-section fractal structure, the asymmetric dual golden-section fractal structure a...

this research is carried out to design and manufacturing of lathe vibration tool and their tests. firstly, one-dimensional vibration tool is designed and made of the bending vibration mode. one-dimensional vibration tool with half piezoelectric rings is considered to excite the bending mode of tool. structure of vibration tool is designed in abaqus software about 20 khz and then is made with re...

[1] For simplicity, a constant gravitational acceleration (~g) is assumed in many general circulation models (GCMs). To estimate the influence of the altitudinal variation of the ~g on the thermosphere simulation, two runs have been made under the solar maximum condition using the non-hydrostatic Global Ionosphere Thermosphere Model (GITM), including one with a constant ~g (8.7 m/s) and the oth...

In this paper we present a nonlinear programming solution to one of the most challenging problems in trajectory optimization. Unlike most aerospace trajectory optimization problems the ascent phase of a hypersonic vehicle has to undergo large changes in altitude and associated aerodynamic conditions. As a result, its aerodynamic characteristics, as well as its propulsion parameters, undergo dra...

To investigate the influence of hypoxia during the early stage of incubation on embryonic developmentand hatching events, and consequently on incidence of ascites in broiler chickens, one thousand fertile eggswere incubated in two commercial incubators. Half the eggs were incubated in a low altitude incubator untilhatched. The second half were incubated in a high altitude incubator until day 10...

This paper describes CHEM2D-H2O, a new parameterization of H2O photochemical production and loss based on the CHEM2D photochemical-transport model of the middle atmosphere. This parameterization accounts for the altitude, latitude, and seasonal variations in the photochemical sources and sinks of water vapor over the pressure region from 100–0.001 hPa (∼16–90 km altitude). A series of free-runn...

This study documents differences in fish assemblages for 32 freshwater streams located between 258 and 2242 m a.s.l. on the eastern slopes of the central range of the Colombian Andes. A total of 2049 fishes belonging to 62 species, 34 genera and 16 families were collected. Species richness declined rapidly with altitude; nearly 90% of the species were recorded between 250 and 1250 m a.s.l. Thre...