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M. Sapigni M. Berti E. Bethaz A. Busillo G. Cardone 《International Journal of Rock Mechanics and Mining Sciences》2002,39(6):771-788
Three tunnels for hydraulic purposes were excavated by tunnel-boring machines (TBM) in mostly hard metamorphic rocks in Northern Italy. A total of 14 km of tunnel was surveyed almost continually, yielding over 700 sets of data featuring rock mass characteristics and TBM performance. The empirical relations between rock mass rating and penetration rate clearly show that TBM performance reaches a maximum in the rock mass rating (RMR) range 40–70 while slower penetration is experienced in both too bad and too good rock masses. However, as different rocks gives different penetrations for the same RMR, the use of Bieniawski's classification for predictive purpose is only possible provided one uses a normalized RMR index with reference to the basic factors affecting TBM tunneling. Comparison of actual penetrations with those predicted by the Innaurato and Barton models shows poor agreement, thus highlighting the difficulties involved in TBM performance prediction. 相似文献
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An objective function for optimization-based smoothing is proposed for both linear and quadratic triangular and quadrilateral elements. Unlike currently published objective functions that are used to perform smoothing or untangling separately, this objective function can be used to untangle and smooth a mesh in a single process. The objective function is designed in such a way that it is easy and straightforward to be extended to higher order elements. The objective function has higher order continuous derivatives that make it suitable for optimization techniques. It has been shown empirically that the proposed function only has one minimum. With the integration of the proposed new objective function into our optimization-based smoothing algorithm, our combined Laplacian/optimization smoothing scheme provides us with satisfactory high quality meshes. 相似文献
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Knowledge of how invasive species use invaded habitats can aid in developing management practices to exclude them. Swan Lake, a 1100‐ha Illinois River (USA) backwater, was rehabilitated to restore ecosystem functions, but may provide valuable habitat for invasive bigheaded carps [bighead carp (Hypophthalmichthys nobilis) and silver carp (H. molitrix)]. Use (residency and passages) of Swan Lake by invasive bigheaded carps was monitored using acoustic telemetry (n = 50 individuals/species) to evaluate the use of a large, restored habitat from 2004 to 2005. Passages (entrances/exits) by bigheaded carps were highest in winter, and residency was highest in the summer. Bighead carp backwater use was associated with the differences in temperature between the main channel and backwater, and passages primarily occurred between 18:00 h and midnight. Silver carp backwater use was positively correlated with water level and main channel discharge, and fewer passages occurred between 12:00 h and 18:00 h than during any other time of day. Harvest occurring during summer or high main channel discharge could reduce backwater abundances while maintenance of low water levels could reduce overall backwater use. Conclusions from this study regarding the timing of bigheaded carps' use of backwater habitats are critical to integrated pest management plans to control invasive species. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
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Marzia Simoni Patrizia Biavati Laura Carrozzi Giovanni Viegi Paolo Paoletti Gino Matteucci Gian Luigi Ziliani Edmondo Ioannilli Tristano Sapigni 《Indoor air》1998,8(2):70-79
Abstract A total of 140 homes in the Po River Delta area of North Italy (near Venice) were monitored during summer and winter to measure the concentration of nitrogen dioxide (NO2), and respirable suspended particulate matter (RSP, ≤ 2.5 μm). In this paper, the findings on home characteristics, daily activity pattern of occupants, and residential indoor air quality are described. Our study confirms that people spend the greater part of their daily lives indoors (84%), especially at home (64%). The concentration of monitored pollutants was greater in winter than in summer. The highest levels of NO2 were found in the kitchens. Significantly higher indoor NO2 levels were found in the houses with gas-furnace heating and/or with gas water heater located inside the home. RSP was significantly higher in homes where tobacco smoking took place, and was significantly related to the number of cigarettes smoked. A significant relationship between NO2 indoor concentrations and RSP values in both seasons was found. 相似文献
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