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101.
Turbulence and turbulent flux events in a small estuary 总被引:2,自引:0,他引:2
Relatively little systematic research has been conducted on the turbulence characteristics of small estuaries. In the present study, detailed measurements were conducted in a small subtropical estuary with a focus on turbulent flux events. Acoustic Doppler velocimeters were installed in the mid-estuary at fixed locations and sampled simultaneously and continuously for 50 h. A turbulent flux event analysis was performed for the entire data sets extending the technique of Narasimha et al. (Phil Trans R Soc Ser A 365:841–858, 2007) to the unsteady open channel flow motion and to turbulent sub-events. Turbulent bursting events were defined in terms of the instantaneous turbulent flux. The data showed close results for all ADV units. The very-large majority of turbulent events lasted between 0.04 and 0.3 s with an average of 1 to 4 turbulent events observed per second. A number of turbulent bursting events consisted of consecutive turbulent sub-events, with between 1 and 3 sub-events per main event on average. For all ADV systems, the number of events, event duration and event amplitude showed some tidal trends, with basic differences between high- and low-water periods. A comparison between the present estuary data and the atmospheric boundary layer results of Narasimha et al. (Phil Trans R Soc Ser A 365:841–858, 2007) showed a number of similarities and demonstrated the significance of turbulent events in environmental flows. A burstiness index of 0.85 was found for the present data. 相似文献
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Hubert Trzaska 《The Environmentalist》2005,25(2-4):181-185
Summary The paper discusses several aspects of the practical application of the SAR. It is shown that the unit is an ideal solution
for basic research and laboratory experiments. SAR is directly nonmeasurable unit. Although methods and devices based upon
indirect SAR measurements may widen our knowledge about EM energy distribution and absorption within a body. It is shown that
for practical applications the temperature SAR measurement methods are not sensitive enough while methods based upon E(H) measurement are less accurate than traditional approaches. As a result of assumption SAR = 4 W/kg as a basic restriction
the present protection standards are illogical and nonrealiazable. A return to traditional units (E, H, S) in the standards
and surveying metrology is suggested. 相似文献
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Jacqueline S. Hubert Robert M. Candelaria Bernard Rosenblum Howard G. Applegate 《Journal of the Air & Waste Management Association (1995)》2013,63(3):259-261
In an era when the cost of compliance with state and federal environmental laws is rapidly rising, sometimes entities, such as operators of waste sites, are unable to pay these and other operating costs and are forced to file for bankruptcy. Citing Midlantic Nat'l Bank v. N.J. Dep't of Envtl. Protection and state environmental laws, bankruptcy trustees may be suing PRPs in bankruptcy courts to share the costs to clean up debtors' waste sites. This article suggests strategies by which PRPs can avoid litigating such lawsuits in the bankruptcy courts and instead resolve them before state and/or federal forums—where they properly belong. 相似文献
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In an open channel, a change from a supercritical to subcritical flow is a strong dissipative process called a hydraulic jump. Herein some new measurements of free-surface fluctuations of the impingement perimeter and integral turbulent time and length scales in the roller are presented with a focus on turbulence in hydraulic jumps with a marked roller. The observations highlighted the fluctuating nature of the impingement perimeter in terms of both longitudinal and transverse locations. The results showed further the close link between the production and detachment of large eddies in jump shear layer, and the longitudinal fluctuations of the jump toe. They highlighted the importance of the impingement perimeter as the origin of the developing shear layer and a source of vorticity. The air–water flow measurements emphasised the intense flow aeration. The turbulent velocity distributions presented a shape similar to a wall jet solution with a marked shear layer downstream of the impingement point. The integral turbulent length scale distributions exhibited a monotonic increase with increasing vertical elevation within 0.2 < Lz/d1 < 0.8 in the shear layer, where Lz is the integral turbulent length scale and d1 the inflow depth, while the integral turbulent time scales were about two orders of magnitude smaller than the period of impingement position longitudinal oscillations. 相似文献