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31.
Packing material formulation for odorous emission biofiltration 总被引:1,自引:0,他引:1
In biological gas treatment, like biofiltration of volatile organic compounds or odorous substances, the microbial nutritional needs could be a key factor of the process. The aim of this work is to propose a new packing material able to provide the lacking nutrients. In the first part of this study, two kinds of material composed of calcium carbonate, an organic binder and two different nitrogen sources, ammonium phosphate and urea phosphate (UP), were compared. The new supports present bulk densities between 0.88 and 1.15g cm(-3), moisture retention capacities close to 50% and 70%, and water cohesion capacities greater than six months for the material with 20% binder. In the second part, oxygen consumption measurements in liquid experiments show that these packing materials could enhance bacterial growth compared to pine bark or pozzolan and have no inhibitory effect. The biodegradation of different substrates (sodium sulfide and ammonia) and the support colonization by the biomass were evaluated. Finally, UP 20 was chosen and tested in a hydrogen sulfide or ammoniac biofiltration process. This showed that, for H2S concentrations greater than 100mg m(-3), UP 20 has a real advantage over pine bark or pozzolan. 相似文献
32.
Daniel P. Cartamil Chugey A. Sepulveda Nicholas C. Wegner Scott A. Aalbers Andres Baquero Jeffrey B. Graham 《Marine Biology》2011,158(4):935-944
The common thresher shark (Alopias vulpinus) is a secondary target species of the California drift gillnet fishery (CA-DGN) and supports a growing recreational fishery
in California waters. This study used archival tags to examine the movement patterns and habitat preferences of common threshers
of the size range captured in the CA-DGN (>120 cm fork length). Depth and temperature-logging archival tags were deployed
on 57 subadult and adult common threshers in the Southern California Bight. Tags from five individuals (8.8%) were recovered,
and 154 days of data were successfully obtained from four of these. By night, shark movements were primarily limited to waters
above the thermocline, which ranged in depth from 15 to 20 m. Sharks were significantly deeper by day, and daytime vertical
distribution consisted of two distinct modes: a ‘shallow mode’ (wherein sharks occupied only the upper 20 m of the water column)
and a ‘deep mode’ (characterized by frequent vertical excursions below the thermocline). This modal switch is interpreted
as relating to regional differences in abundance of surface-oriented prey and prey in deeper water. Maximum dive depth was
320 m, greatest dive duration was 712 min, minimum temperature experienced during a dive was 9.1°C, and dive descent rate
was significantly greater than ascent rate. Sharks inhabited waters corresponding to a sea surface temperature range of 16
to 21°C. The nocturnal depth distribution of common threshers has implications for management of drift gillnet deployment
depths in the CA-DGN. 相似文献
33.
采用分布式混合试验系统模拟四层钢结构框架在强震下的倒塌行为。变形集中的首层作为试验对象,而上部结构作为数值子结构。各子结构通过协调器满足界面上的平衡和协调条件,并被协调器的输入输出接口封装起来。采用柔性的试验方案,可以在当前有限控制精度的限制下,灵活地处理边界条件。试验结果与日本E-D efense振动台足尺试验结果进行了对比,得到了类似的倒塌机制,证明混合试验有能力进行结构倒塌模拟,而误差主要来自于模型简化。 相似文献
34.
This article argues that climate change, seen as a socially constructed anticipation of natural disasters and a future-risk that plays out in present politics, is enabling the emergence of new modes of governance in cities of the global south. The article focuses on the process by which the city of Esmeraldas, Ecuador, developed a Climate Change Adaptation and Mitigation Strategy. Within the context of climate change adaptation, Esmeraldas mobilised new discourses, stakeholders, and planning mechanisms to address pre-existing urban planning and development limitations. This discursively enabled the municipality's ongoing governance project by leveraging resources, creating consensus, and informing practice. Climate change adaptation thus became an important mechanism for engaging with local priorities, particularly those of the most vulnerable populations, and for bridging the gap between the formal world of policymaking and the reality of life in the city, which is more often structured by informality. 相似文献
35.
Edgar Hernandez-Andrade Jesus Andres Benavides Serralde Rogelio Cruz-Martinez 《黑龙江环境通报》2012,32(2):103-112
Assessment of the fetal cerebral circulation provides important information on the hemodynamic changes associated with chronic hypoxia and intrauterine growth restriction. Despite the incorporation of new US parameters, the landmark for the fetal brain hemodynamic evaluation is still the middle cerebral artery. However, new vascular territories, such as the anterior and posterior cerebral arteries, might provide additional information on the onset of the brain sparing effect. The fractional moving blood volume estimation and three-dimensional power Doppler ultrasound indices are new techniques that seem to be promising in indentifying cases at earlier stages of vascular deterioration; still, they are not available for clinical application and more information is needed on the reproducibility and advantages of three-dimensional power Doppler ultrasound blood flow indices. In the past, the brain sparing effect was considered as a protective mechanism; however, recent information challenges this concept. There is growing evidence of an association between brain sparing effect and increased risk of abnormal neurodevelopment after birth. Even in mild late-onset intrauterine growth restriction affected fetuses with normal umbilical artery blood flow, increased cerebral blood perfusion can be associated with a substantial risk of abnormal neuroadaptation and neurodevelopment during childhood. © 2012 John Wiley & Sons, Ltd. 相似文献
36.
37.
Andres Gartmann Mathias D. Müller Eberhard Parlow Roland Vogt 《Environmental Fluid Mechanics》2012,12(2):185-200
Studying urban air-transport phenomena is highly complex, because of the heterogenous flow patterns that can arise. The main
reason for these is the variable topology of urban areas, however, there is a large number of influencing variables such as
meteorological conditions (e.g., wind situation, temperature) and anthropogenic factors such as traffic emissions. During
a one-year CO2 measurement campaign in the city of Basel, Switzerland, steep CO2 gradients were measured around a large building. The concentration differences showed a strong dependency on the local flow
regimes. Analysis of the field data alone did not provide a complete explanation for the mechanisms underlying the observed
phenomena. The key numerical parameters were defined and the influence of turbulent kinetic energy dependency on the time
interval for the Reynolds decomposition was studied. A Reynolds-Average Navier-Stokes Computational Fluid Dynamics (CFD) approach
was applied in the study area and the CO2 concentrations were simulated for six significant meteorological situations and compared to the measured data. Two flow regimes
dependent on the wind situation, which either enhanced or suppressed the concentration of CO2 in the street canyon, were identified. The enhancement of CO2 in the street canyon led to a large difference in CO2 concentration between the backyard- and street-sides of a building forming the one wall of the canyon. The specific characteristics
of the flow patterns led to the identification of the processes determining the observed differences in CO2 concentrations. The combined analysis of measurement and modeling showed the importance of reliable field measurements and
CFD simulations with a high spatial resolution to assess transport mechanisms in urban areas. 相似文献
38.
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40.
Andres R. Garcia-Martin Frederick N. Scatena Glenn S. Warner Daniel L. Civco 《Journal of the American Water Resources Association》1996,32(6):1259-1271
ABSTRACT: Statistical analysis of watershed parameters derived using a Geographical Information system (GIS) was done to develop equations for estimating the 7d–10yr, 30d–10yr, and 7d–2yr low flow for watersheds in humid montane regions of Puerto Rico. Digital elevation models and land use, geology, soils, and stream network coverages were used to evaluate 21 geomorphic, 10 stream channel, 9 relief, 7 geology, 4 climate, and 2 soil parameters for each watershed. To assess which parameters should be used for further investigation, a correlation analysis was used to determine the independence and collinearity among these parameters and their relationship with low flows. Multiple regression analyses using the selected parameters were then performed to develop the statistical models of low flows. The final models were selected in the basis of the Mallow Cp statistic, the adjusted R2, the Press statistic, the degree of collinearity, and an analysis of the residuals. In the final models, drainage density, the ratio of length of tributaries to the length of the main channel, the percent of drainage area with northeast aspect, and the average weighted slope of the drainage were the most significant parameters. The final models had adjusted standard errors of 58.7 percent, 59.2 percent, and 48.6 percent for the 7d–10yr, 30d–10yr, and 7d–2yr low flows respectively. For comparison, the best model based on watershed parameters that can be easily measured without a GIS had an adjusted standard error of 82.8 percent. 相似文献