This paper investigates, experimentally and numerically, the shear velocity distribution along a single transverse dune and along two closely spaced dunes, analyzing the flow effects of one dune upon the other. The paper focuses on two-dimensional models simulating transverse sand dunes. The shape of the two pile geometries studied is described by sinusoidal curves, one having a maximum slope of $32^{\circ }$ and the other $27.6^{\circ }$, with leeward flow separation. The tests were carried out for two undisturbed wind speeds and the experimental data obtained through wind-tunnel modeling encompass flow visualization and shear-velocity results. A generally good agreement is observed between the experimental measurements and computational results. From the inquiry between shear velocity distributions and published eroded contours for the same geometries, it appears the Bagnold’s approach is insufficient in the prediction of threshold conditions in wake flows formed in the dune’s leeward side. 相似文献
Journal of Polymers and the Environment - Biodegradability is a key feature for the application of polymeric devices in medicine. This study reports an experimental and theoretical study of the... 相似文献
Wastes with residual heating value, according to the trend of the world legislation, could be thermally reused. The present study is conducted to verify the possibility of thermal valorisation of a waste, denominated fluff, by injection in blast furnace. The fluff, arising from the automobile shredder operations, is a waste characterised by a high organic matrix and is potentially dangerous due to the heavy metals, oils filter and halogenated plastics content. The first step of the work is the chemical, physical and toxicological characterisation of this material. Then the fluff injection in a blast furnace tuyere is theoretically analysed with a mathematical model. Finally, experimental trials are conducted in a pilot plant, simulating the most important part of the blast furnace: the raceway, in order to analyse process and industrial aspects. In view of an industrial application a first economical evaluation is carried out on the basis of model and experimental results. 相似文献
The coastline of the state of Rio Grande do Sul (Brazil) is used annually as a migratory route by a number of seabird species.
Thirteen surveys were carried out between July 1997 and July 1998 to obtain information on the diet of Puffinus gravis, Puffinus griseus, and Puffinus puffinus along the coast of Rio Grande do Sul. Sampling efforts focused on dead beach-cast specimens. One hundred twenty-one stomach
content analyses were performed on P. gravis from a total of 238 specimens; 17 stomach content analyses were performed on P. griseus from a total of 54 specimens; and 25 stomach content analyses were performed on 25 P. puffinus from a total of 61 dead specimens. Cephalopods were the main prey found in the stomachs of the three species and were present
in 96% of the P. gravis stomachs. The following cephalopods were observed: Ommastrephidae, Gonatus antarcticus, Gonatus sp., Lycoteuthis lorigera, Lycoteuthis sp., Histioteuthis sp., Cycloteuthis sp., Loligo plei, Loligo sanpaulensis, Sepiidae, and Argonauta nodosa. The latter was the most abundant species in the three species of Puffinus. The following fish were identified from otoliths: Porichthys porosissimus, Ctenosciaena gracilicirrhus, Paralonchurus brasiliensis, Cynoscion guatucupa, and Trichiurus lepturus. There was also a high incidence of synthetic materials such as plastic, polyethylene and rubber. 相似文献
The objective of this study was to evaluate pesticide poisonings in the southern region of Brazil between years 1999 and 2014. Data were collected from the database Sinitox. Intoxications and deaths were evaluated according to the distribution by gender (female and male), age group (≤14, 15–59 and ≥60 years), area of occurrence (urban and rural), circumstance (accident, occupational and suicide attempt) and evolution of the cases over time (cure, unconfirmed cure, death and sequelae). In the evaluated period, 21,305 cases of intoxication were registered. The results show that males between the ages of 15 and 59 years are more affected; and there is a greater representativeness in the urban area. These results are related to the application of agrochemicals being carried out by individuals between 15 and 59 years of age. The great correlation of urban area possibly occurs in function of the air currents brought from the field and as a result, population has been more affected and the consumption of contaminated food. It was observed that women handling pesticides more cautiously, in this way the accidents with male gender are more frequent, however, many women use the product intentionally to provoke suicide. 相似文献
The increasing concern regarding the preservation of soil quality suggests the adoption of quality reference values as a first step in environmental monitoring actions. In this context, the objective of this study was to establish soil quality reference values for Al, Zn, Mn, Cd, Fe, Pb, Ni, Cr, and Cu and to correlate several soil properties with the occurrence of these elements in the hillslope region of Rio de Janeiro State. Sixty-two samples were collected at depths of 0–20 and 20–40 cm and analyzed using the USEPA method 3051A. After clustering analysis, the samples were separated into three groups. Classification functions were obtained based on the variables pH - Mg - Fe - Mn, i.e., the variables that were best related to heavy metal content. We determined to establish the quality reference values for the 75th percentile of the three groups. The relief forms of the area, which facilitate the transport of soil fine-particle fractions and accumulation in lowlands, were revealed to be one of most important factors in understanding the distribution of soil heavy metals. 相似文献
Objective: Although most research on drugs and driving has focused on the use of alcohol and cannabis, research that has been conducted on cigarette smoking and collisions has found that smokers have an increased collision involvement. Studies dating from 1967 through 2013 have shown a crude relative risk of about 1.5 among smokers compared to nonsmokers. In Canada, the association between smoking and collisions has not been recently investigated. Studies that have examined the association between smoking and collisions often did not control for all confounding factors, such as alcohol use and driving exposure, which have been associated with increased collision rates. Additionally, a number of these studies were examined in countries and at times when prevalence of smoking was much higher than is currently the case in Canada. The purpose of this research is to examine the association between self-reported current smoking and past-year collision involvement, controlling for confounding factors, in a large representative sample of adult drivers in Ontario, Canada, from 2002 and 2014.
Method: Data are based on the Centre for Addiction and Mental Health (CAMH) Monitor, an ongoing, rolling telephone survey of Ontario adults that provides epidemiological surveillance of indicators related to alcohol, tobacco, and other drug use, as well as physical and mental health. The survey uses random-digit-dialing methods via Computer-Assisted Telephone Interview, with response rates over 50%.
Results: Prevalence of self-reported collision involvement within the past year for 2002–2014 was 8.6% among those who currently smoke compared to 6.5% of nonsmokers. Logistic regression analysis, controlling for the potential confounding effects of sociodemographics, driving exposure measures, drinking frequency, and hazardous alcohol use, found that the overall odds for collision involvement in the preceding year among current smokers for 2002–2014 was 1.27 (95% confidence interval [CI], 1.06–1.53) times that of nonsmokers.
Conclusions: These findings indicate that despite a substantial reduction in overall prevalence of smoking in Canada, smokers still have a significantly increased odds of collision involvement, even when controlling for alcohol and exposure. Additionally, the results are consistent with the increased odds/risks of motor vehicle collisions found in other countries. 相似文献