نتایج جستجو برای: double sand lenses
تعداد نتایج: 282103 فیلتر نتایج به سال:
A method has been developed whereby refractive microlenses can be produced in poly (methyl methacrylate) by excimer laser irradiation at λ = 248 nm. The lenses are formed by a combined photochemical and thermal process. The lenses are formed as depressions in the substrate material (negative focal length), which makes replication necessary in order to obtain lenses with a positive focal length....
[1] The 26 December 2004 tsunami caused widespread destruction and contamination of coastal aquifers across southern Asia. Seawater filled domestic open dug wells and also entered the aquifers via direct infiltration during the first flooding waves and later as ponded seawater infiltrated through the permeable sands that are typical of coastal aquifers. In Sri Lanka alone, it is estimated that ...
in civil engineering concrete is a material combined of hydraulic cement, sand, gravel and water. gravel and sand compose 60 to 70 percent of concrete. these aggregates support compression force of concrete. cement paste acts as glue to stick grain together. in bushehr factories producing aggregates do not operate according to astm standards, so that fineness modulus (fm) of the produced sands ...
OBJECTIVES To determine if a plano lens could be the test lens for all prescription (Rx) lenses and to investigate why Rx lenses pop out of safety eyewear. DESIGN Plano and Rx polycarbonate lenses (n = 641) with varying thickness and edge geometry, mounted on steel lens holders, and Rx safety eyewear (n = 128) placed on headforms were impacted with test objects of varying diameter and hardnes...
PURPOSE To investigate the efficacies of different concentrations of N-acetylcysteine (NAC) in preventing hyperoxia-induced lens opacification and changes to biochemical parameters in organ-cultured rabbit lenses. METHODS Thirty-six lenses from adult rabbits were divided into the control group (group A), the hyperoxia-exposed group (group B), and the hyperoxia-exposed, NAC-treated groups: 5 m...
Young animals compensate for defocus imposed by positive or negative spectacle lenses by adjusting the elongation rate of their vitreous chambers, thus matching the length of the eye with the focal length of the eye's optics combined with the spectacle lenses. The ability to compensate for either negative or positive lenses could rely on the ability to distinguish between myopic and hyperopic b...
This experiment compared the effects of sand and straw bedding in free stalls on resting time, cleanliness, hock injuries, and hoof health of dairy cows and tested whether cow preferences for a bedding material depended on the familiarity with the material. A total of 52 dairy cows were kept either on straw bedded concrete stalls or sand stalls for at least 21 wk. The lying behavior was observe...
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