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401.
Akshay A. Gowardhan Michael J. Brown Eric R. Pardyjak 《Environmental Fluid Mechanics》2010,10(3):311-328
This work describes and evaluates a pressure solver that has been incorporated into a fast response three-dimensional building-resolving
diagnostic wind modeling system. The solver computes the three-dimensional pressure field around buildings and on exterior
walls in terms of a coefficient of pressure by solving a simplified pressure Poisson equation (that neglects turbulence stresses
in the Navier-Stokes) for incompressible flow. The input to the solver is the three-dimensional mean wind field obtained from
a fast response empirical-diagnostic urban wind model. The present study is an evaluation of the pressure solver using wind-tunnel
data for flow normal to and at a 45° angle to an isolated cubical building. Results for the normal incident wind angle case
indicate that the model satisfactorily reproduces the general spatial patterns and the magnitude of the pressure difference
around much of the cube. Details of the flow field that are not satisfactorily predicted include the spatial distribution
of pressure on the roof and the lower half of the front side of the building and the magnitude along the sidewalls where pressures
are over predicted. The results for the 45° case show reasonable agreement between the model and experiments on the front
and the back walls, but over predict pressures on the leading edge of the rooftop. Regions with poor pressure predictions
appear to be a result of unsatisfactory mean wind modeling. 相似文献
402.
Jorge M. Mendes Patrícia Cortés de Zea Bermudez José Pereira K. F. Turkman M. J. P. Vasconcelos 《Environmental and Ecological Statistics》2010,17(1):1-28
In Portugal, due to the combination of climatological and ecological factors, large wildfires are a constant threat and due
to their economic impact, a big policy issue. In order to organize efficient fire fighting capacity and resource management,
correct quantification of the risk of large wildfires are needed. In this paper, we quantify the regional risk of large wildfire
sizes, by fitting a Generalized Pareto distribution to excesses over a suitably chosen high threshold. Spatio-temporal variations
are introduced into the model through model parameters with suitably chosen link functions. The inference on these models
are carried using Bayesian Hierarchical Models and Markov chain Monte Carlo methods. 相似文献
403.
Ryoko Fujiyoshi Yukihide Haraki Takashi Sumiyoshi Hikaru Amano Ivan Kobal Janja Vaupotič 《Environmental geochemistry and health》2010,32(1):73-82
Radon (222Rn) and carbon dioxide were monitored simultaneously in soil air under a cool-temperate deciduous stand on the campus of Hokkaido
University, Sapporo, Japan. Both 222Rn and CO2 concentrations in soil air varied with atmospheric (soil) temperature in three seasons, except for winter when the temperature
in soil air remained constant at 2–3°C at depth of 80 cm. In winter, the gaseous components were influenced by low-pressure
region passing through the observation site when the ground surface was covered with snow of ~1 m thickness. Carbon isotopic
analyses of CO2 suggested that CO2 in soil air may result from mixing of atmospheric air and soil components of different origins, i.e. CO2 from contemporary soil organic matter and old carbon from deeper source, to varying degrees, depending on seasonal meteorological
and thus biological conditions. 相似文献
404.
Vittorio Barale 《Journal of Coastal Conservation》2010,14(4):317-326
The ecosystem approach requires that all elements of an ecosystem, and their mutual interactions, be taken into consideration
in any management effort. The selection of suitable geographical units, where this approach can be taken, requires the assessment
of ecological provinces, characterized by a coherent set of environmental traits. The marine side of coastal zones, where
the interaction between atmosphere, land and sea is not bounded by evident geographic markers, represents a critical factor
in this assessment. A coastal province can be defined by physical setting, but also by its bio-geo-chemical features, ideally
on the basis of synoptic remote sensing data, collected at space/time scales not accessible by other means. Classifications
based on indicators such as temperature, wind speed and chlorophyll-like pigments, demonstrate the identification of potential
ecological provinces in the Mediterranean Sea. The results suggest remote sensing as the ideal tool to set up the basis for
an ecosystem approach to the management of each province. 相似文献
405.
Marco Ghisalberti 《Environmental Fluid Mechanics》2010,10(3):329-343
Obstructed shear flows (i.e. those over permeable media) are common in the environment. An archetypal example, flow over a
submerged vegetation canopy, is investigated here. Like any flow through complex geometry, canopy flows are characterised
by strong spatial gradients. The focus of this experimental study is the three-dimensionality of aquatic canopy flow, in particular
that of the coherent interfacial vortices that govern mixing into and out of the canopy. It is shown here that the vortices
have a finite lateral scale that is comparable to their vertical scale; both are of the order of the drag length scale of
the canopy, (C
D
a)−1, where a is the frontal area density and C
D
is a bulk drag coefficient. The finite lateral extent of the vortices generates strong lateral hydrodynamic gradients, both
instantaneously and in the long-term. The instantaneous gradients, which can contribute greatly to the dispersion of dissolved
and particulate species, are far more pronounced. Finally, the potential for canopies to generate differential roughness secondary
circulation is examined. In the consideration of vertical scalar transport, this circulation can be of the same order as turbulent
diffusion. 相似文献
406.
Persistence models for mark-recapture 总被引:1,自引:0,他引:1
The stable of models available for analyzing mark-recapture data (Otis et al. Wild Momogr 66:135, 1978) includes those having
behavioral characteristics, time variation, heterogeneity, along with combinations of those characteristics. This paper proposes
use of a series of models based on the persistence model of Ramsey and Usner (Biometrics 59:331–339, 2003). We show that persistence
can be modeled in combination with behavior and with time variation. We apply the persistence model to situations in which
capture occasions are not equally-spaced in time. Two case studies illustrate the use of these extended persistence models. 相似文献
407.
Arsenic (As) contamination has become a serious environmental problem in many countries. We have performed batch-type leaching
experiments on mine tailing soils collected from three abandoned mine areas in South Korea with the objective of evaluating
the effect of indigenous bacterial activity on As mobilization. The analysis of physicochemical properties and mineralogical
compositions of the samples indicated that the secondary minerals or phases formed as a result of the oxidation or alteration
of primary minerals were associated with the labile and bioleachable fractions of As. Compared to simulated abiotic processes
using sterilization, the indigenous bacteria activated using a carbon source were able to enhance the dissolution of As under
both aerobic and anaerobic conditions. The bacterial dissolution of iron (Fe) and manganese (Mn) was found to occur simultaneously
with the dissolution of As, suggesting that the main bacterial mechanism was via the dissimilatory reduction of Fe(III),
Mn(IV), and As(V). An anaerobic environment was more favorable for the prominent dissolution of As in the tailing soils. These
results indicate that the mobilization of As can be enhanced in the oxygen-depleted part of the tailing dump, particularly
with the infiltration of organic substrates. The difference in the degree of As lixiviation between the three tailing soils
was found to be related to the bioavailability of As as well as the original biomass in the tailing soils. 相似文献
408.
Climate change associated with sea level rise (SLR) is one of the major environmental concerns of today. This paper presents
an assessment of the impacts of sea level rise on the coastal zone of Kanyakumari District in Tamilnadu, India. Digital Elevation
Model (DEM) combined with overlay techniques in GIS are used in determining the inundation zones along the coastal region.
The analysis evaluated the impact on coastal fishing villages, landuse, tourist spots and sensitive areas under threat. The
vulnerability of the coastal areas in Kanyakumari to inundation was quantified, based on the projected sea level rise scenarios
of 0.5 and 1 m. Our findings reveal that approximately 13 km2 of the land area of Kanyakumari would be permanently inundated due to SLR. This would result in loss of land, alteration
of the coastal zone and affects coastal ecosystem. From the study, the mitigation measures (engineering measures) and Coastal
Zone Management practices that can be taken to protect human life and property from sea level rise are suggested. 相似文献
409.
Kazuharu Yoshizuka Syouhei Nishihama Hideki Sato 《Environmental geochemistry and health》2010,32(4):297-302
The objective of this study was to survey the cation and anion contents of geothermal waters to gather fundamental information on geographical variations. Sixteen sites in hot spring areas on the island of Kyushu in Japan were studied. The study focused on the arsenic content of the samples. Very high arsenic concentrations (more than 0.1 mg/l) were detected in most of the geothermal waters sampled. High contents of boron and fluoride (more than 1.0 mg/l) were also detected in some samples. Arsenic removal was performed on a laboratory scale using columns packed with a magnetite-type adsorbent. The reduction of arsenic contamination to a concentration of less than 0.01 mg/l could be achieved in the early stages of adsorption (bed volume = 200). 相似文献
410.
Anthropogenic influence on surface water quality of the Nhue and Day sub-river systems in Vietnam 总被引:2,自引:0,他引:2
Pham Thi Minh Hanh Suthipong Sthiannopkao Kyoung-Woong Kim Dang The Ba Nguyen Quang Hung 《Environmental geochemistry and health》2010,32(3):227-236
In order to investigate the temporal and spatial variations of 14 physical and chemical surface water parameters in the Nhue
and Day sub-river systems of Vietnam, surface water samples were taken from 43 sampling sites during the dry and rainy seasons
in 2007. The results were statistically examined by Mann–Whitney U-test and hierarchical cluster analysis. The results show that water quality of the Day River was significantly improved during
the rainy season while this was not the case of the Nhue River. However, the river water did not meet the Vietnamese surface
water quality standards for dissolved oxygen (DO), biological oxygen demand (BOD5), chemical oxygen demand (COD), nutrients, total coliform, and fecal coliform. This implies that the health of local communities
using untreated river water for drinking purposes as well as irrigation of vegetables may be at risk. Forty-three sampling
sites were grouped into four main clusters on the basis of water quality characteristics with particular reference to geographic
location and land use and revealed the contamination levels from anthropogenic sources. 相似文献