Streamwise Versus Spanwise Spacing of Obstacle Arrays: Parametrization of the Effects on Drag and Turbulence     

Andres Simón-Moral  Jose Luis Santiago  E. Scott Krayenhoff  Alberto Martilli 《Boundary-Layer Meteorology》2014,151(3):579-596

A Reynolds-averaged Navier–Stokes model is used to investigate the evolution of the sectional drag coefficient and turbulent length scales with the layouts of aligned arrays of cubes. Results show that the sectional drag coefficient is determined by the non-dimensional streamwise distance (sheltering parameter), and the non-dimensional spanwise distance (channelling parameter) between obstacles. This is different than previous approaches that consider only plan area density $(\lambda _\mathrm{p})$ . On the other hand, turbulent length scales behave similarly to the staggered case (e. g. they are function of $\lambda _\mathrm{p}$ only). Analytical formulae are proposed for the length scales and for the sectional drag coefficient as a function of sheltering and channelling parameters, and implemented in a column model. This approach demonstrates good skill in the prediction of vertical profiles of the spatially-averaged horizontal wind speed.  相似文献   

Fighting for a future: an actor-oriented planning approach to landscape preservation in Galicia     

Paul Swagemakers  Damian Copena Rodríguez  María Dolores Domínguez García  Xavier Simón Fernández 《Geografisk tidskrift / udgivet af Bestyrelsen for Det Kongelige danske geografiske selskab》2013,113(2):109-118

Modification and channelization of streams and rivers have been conducted extensively throughout the world during the past century. Subsequently, much effort has been directed at re-creating the lost habitats and thereby improving living conditions for aquatic organisms. However, as restoration methods are plentiful, it is difficult to determine which one to use to get the anticipated result. The aim of this study was to compare two commonly used methods in small Danish streams to improve the physical condition: re-meandering and passive restoration through cease of maintenance. Our investigation included measurement of the physical conditions in 29 stream reaches covering four different groups: (1) re-meandered streams, (2) LDC streams (the least disturbed streams available), (3) passively restored streams (>10?years stop of maintenance) and (4) channelized and non-restored streams. The in-stream habitats were compared through analysis of the measured physical parameters and by applying a habitat model. We found that re-meandering is a more effective way of re-creating near-natural physical conditions in small streams compared to passive restoration. This is probably due to the limited energy in small streams which restricts re-shaping of the stream channel. However, based on habitat suitability modelling, the change to the physical condition did not translate into improved habitat suitability for young of the year brown trout highlighting the value of using several methods when evaluating restoration success.  相似文献   

Effects of Antimicrobial Air Filters on the Viability and Culturability of Airborne Bacteria          下载免费PDF全文

Gi Byoung Hwang  Bo Mi Kwon  Seung Jae Lee  Byung Uk Lee  Kyoung Mi Sim  Gwi‐Nam Bae  Jae Hee Jung 《洁净——土壤、空气、水》2016,44(10):1268-1277

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Microbiological and physicochemical analysis of the coastal waters of southern Brazil     

Moresco V  Viancelli A  Nascimento MA  Souza DS  Ramos AP  Garcia LA  Simões CM  Barardi CR 《Marine pollution bulletin》2012,64(1):40-48

The aim of this study was to assess the impact of sewage discharge on coastal waters by evaluating the influence of physicochemical parameters on the presence of enteric microorganisms in seawater samples collected from 11 beaches in Florianopolis, Santa Catarina, Brazil, over a one-year period (August 2009 to July 2010). Samples were assessed for the presence of human adenoviruses (HAdV), polyomavirus (JCPyV), hepatitis A virus (HAV), and noroviruses (HuNoV GI and GII). Escherichia coli and physicochemical parameters (salinity, temperature, pH and dissolved oxygen) were also evaluated. From the 132 samples analyzed, 55% were positive for HAdV, 51.5% for HAV, 7.5% for HuNoV GI, 4.5% for HuNoV GII, and 3% for JCPyV. E. coli levels ranged from 8 to 1325 CFU/100mL at all sites. The overall results highlight the problem of sewage discharge into coastal waters and confirm that there is no correlation between viral presence and bacterial contamination.  相似文献   

Water exchanges between a multi-inlet lagoon and the ocean: the role of forcing mechanisms     

João Pedro Farinha Fabião  Marta Filipa Gomes Rodrigues  André Bustorff Fortunato  José Manuel Quintela de Brito Jacob  Alexandra Maria Francisco Cravo 《Ocean Dynamics》2016,66(2):173-194

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An assessment of the latent and sensible heat flux on the simulated regional climate over Southwestern South Atlantic Ocean     

Michelle Simões Reboita  Rosmeri Porfírio da Rocha  Tércio Ambrizzi  Ernesto Caetano 《Climate Dynamics》2010,34(6):873-889

A Regional Climate Model (RegCM3) 10-year (1990–1999) simulation over southwestern South Atlantic Ocean (SAO) is evaluated to assess the mean climatology and the simulation errors of turbulent fluxes over the sea. Moreover, the relationship between these fluxes and the rainfall over some cyclogenetic areas is also analyzed. The RegCM3 results are validated using some reanalyses datasets (ERA40, R2, GPCP and WHOI). The summer and winter spatial patterns of latent and sensible heat fluxes simulated by the RegCM3 are in agreement with the reanalyses (WHOI, R2 and ERA40). They show large latent heat fluxes exchange in the subtropical SAO and at higher latitudes in the warm waters of Brazil Current. In particular, the magnitude of RegCM3 latent heat fluxes is similar to the WHOI, which is probably related to two factors: (a) small specific humidity bias, and (b) the RegCM3 flux algorithm. In contrast, the RegCM3 presents large overestimation of sensible heat flux, though it simulates well their spatial pattern. This simulation error is associated with the RegCM3 underestimation of the 2-m air temperature. In southwestern SAO, in three known cyclogenetic areas, the reanalyses and the RegCM3 show the existence of different physical mechanisms that control the annual cycles of latent/sensible heating and rainfall. It is shown that over the eastern coast of Uruguay (35°–43°S) and the southeastern coast of Argentina (44°–52°S) the sea-air moisture and heat exchange play an important role to control the annual cycle of precipitation. This does not happen on the south/southeastern coast of Brazil.  相似文献   

South Atlantic Ocean cyclogenesis climatology simulated by regional climate model (RegCM3)     

Michelle Simões Reboita  Rosmeri Porfírio da Rocha  Tércio Ambrizzi  Shigetoshi Sugahara 《Climate Dynamics》2010,35(7-8):1331-1347

A detailed climatology of the cyclogenesis over the Southern Atlantic Ocean (SAO) from 1990 to 1999 and how it is simulated by the RegCM3 (Regional Climate Model) is presented here. The simulation used as initial and boundary conditions the National Centers for Environmental Prediction—Department of Energy (NCEP/DOE) reanalysis. The cyclones were identified with an automatic scheme that searches for cyclonic relative vorticity (ζ₁₀) obtained from a 10-m height wind field. All the systems with ζ₁₀ ≤ ?1.5 × 10^?5 s^?1 and lifetime equal or larger than 24 h were considered in the climatology. Over SAO, in 10 years were detected 2,760 and 2,787 cyclogeneses in the simulation and NCEP, respectively, with an annual mean of 276.0 ± 11.2 and 278.7 ± 11.1. This result suggests that the RegCM3 has a good skill to simulate the cyclogenesis climatology. However, the larger model underestimations (?9.8%) are found for the initially stronger systems (ζ₁₀ ≤ ?2.5 × 10^?5 s^?1). It was noted that over the SAO the annual cycle of the cyclogenesis depends of its initial intensity. Considering the systems initiate with ζ₁₀ ≤ ?1.5 × 10^?5 s^?1, the annual cycle is not well defined and the higher frequency occurs in the autumn (summer) in the NCEP (RegCM3). The stronger systems (ζ₁₀ ≤ ?2.5 × 10^?5 s^?1) have a well-characterized high frequency of cyclogenesis during the winter in both NCEP and RegCM3. This work confirms the existence of three cyclogenetic regions in the west sector of the SAO, near the South America east coast and shows that RegCM3 is able to reproduce the main features of these cyclogenetic areas.  相似文献   

Fragility curves for old masonry building types in Lisbon     

Ana Simões  Jelena Milošević  Helena Meireles  Rita Bento  Serena Cattari  Sergio Lagomarsino 《Bulletin of Earthquake Engineering》2015,13(10):3083-3105

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Relative equilibrium solutions in the four body problem     

Carles Simó 《Celestial Mechanics and Dynamical Astronomy》1978,18(2):165-184

Beyond the casen=3 little was known about relative equilibrium solutions of then-body problem up to recent years. Palmore's work provides in the general case much useful information. In the casen=4 he gives the totality of solutions when the four masses are equal and studies some degeneracies. We present here a survey of solutions for arbitrary masses, discussing the manifolds of degeneracy. The ordering of restricted potentials allows a counting of the number of bifurcation sets and different invariant manifolds. An analysis of linear stability is done in the restricted and general cases. As a result, values of the masses ensuring linear stability are given.  相似文献   

Effects of nutrients on crude oil biodegradation in the upper intertidal zone   总被引：10，自引：0，他引：10  

Oh YS  Sim DS  Kim SJ 《Marine pollution bulletin》2001,42(12):1367-1372

To enhance biodegradation, nutrients in the form of slow-release fertilizer (SRF) were applied to oil-contaminated microcosms (3%, v/v) which simulated intertidal environmental systems. Although nutrient concentrations in the interstitial water were not proportional to those in amended SRF, microbial activity, growth of oil-degrading microorganisms, and oil-degradation rate were closely related to the concentration of nutrients in the interstitial water. Adding nutrients at higher dose (microcosm I, 144.4 mg C/kg sand/day, versus microcosm II, 8.5 mg C/kg sand/day) had a positive effect on oil degradation rate, which was especially obvious during the early phase of treatment. Use of pristane, phytane, and nor-hopane as biomarkers enabled the detection of significant treatment differences in hydrocarbon biodegradation, which were not reliable enough when the data were normalized to sand mass.  相似文献