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The purpose of this study is to evaluate the effect of one abrasive cleaner, one non-abrasive cleaner and one non-abrasive alcohol-based cleaner on the lens parameter stability of the NOVALENS. Twenty-four lenses, all NOVALENS material of identical design, were cleaned 100 times each. Eight lenses were cleaned with MiraFlow (CIBA Vision), eight lenses with Optic-Free Daily Cleaner and eight lenses with the Gas Permeable Daily Cleaner (PBH). The base curve radius, center thickness and power were verified immediately before, immediately after and (per manufacturer's recommendation) 4 hours after cleaning at baseline, 25, 50, 75 and 100 cleanings. Lens toricity of approximately 0.50D was found with all three cleaners after 100 cleanings. No change in lens power or center thickness was found. It was concluded that extreme care must be taken in handling the NOVALENS due to the potential of induced warpage. 相似文献
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John E. Beard
Malcolm E. Wright
Michael MailanderMark Miller
《Mechanism and Machine Theory》1992,27(6):635-644The design of a specialized agricultural harvesting machine required the use of a path generation mechanism that was compact, accurate, inexpensive to manufacture and difficult attempts involved the use of a cam and follower, but they were expensive to manufacture and difficult to operate. This paper discusses an alternative method of using a coupled, open loop, two-link mechanism to generate a polygon-like closed path (pseudo-polygon) with an integer number of curved sides and apexes. A complete development of the path and path curvaturei equations are presented. The influence of the design variables on the coupler shape (flatness of each side) is shown in equation and design chart form. An example of a successful application of this design method applied to a plant cutting mechanism is presented. 相似文献
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Capital cost correlations are given for oil-water separators, equalization basins, primary clarifiers, clarifiers and clarifier mechanisms, reverse osmosis unit, ultrafiltration units, gravity filters and miroscreens. Data are included for raw sewage, intermediate and recirculation pumping stations and for preliminary treatment (or bar screens, grit removal, overflow and bypass chamber and Parshall flume), for grit removal, comminution and gas stripping. The correlations are accurate to ± 30%, expressed in Canadian dollars and adjusted to a Marshall and Swift value of 1000. Details as to what components are included in the cost are given. Data are given for the labour and material costs to create a working process module. For inflation indices, a critique of the Engineering News Record, EPA small city, Marshall and Swift, Chemical Engineering and Southam inflation indices suggested that the Marshall and Swift index is most appropriate for the construction and process equipment studied here. Concerning the currency exchange, for the equipment and processes in this study, equipment costs the same whether expressed directly in US or Canadian dollars. To put the current data into perspective, several hundred sources of cost data were analyzed. The major correlations are compared, on a consistent basis, with current data. 相似文献
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