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71.
Visual and auditory alerts are increasingly important and have many applications, particularly in the presentation of hazard information in transportation and many industrial systems. This paper is concerned with the factors that govern the relative effectiveness of alerting signals involving various combinations of visual and auditory signals. The visual variables were colour, flash rate, and flash mode, combined with or without an auditory alarm. It was found that the subjects associated different levels of hazard with different alerting light colours, flash rates, flashing modes, and with combinations of auditory and visual alerts. A red flashing light was perceived as the most effective hazard warning colour, with yellow and blue warning lights indicative of less hazardous situations. The faster the flash rate, the greater is the hazard perceived. A flash rate of 60 fpm (flashes per minute) was not as effective as the rates of 180 and 240 fpm, and 240 fpm was the most effective. This implies that hazard warning signal should flash at well above 60 fpm. Having a breakup in the flashing pattern so as to provide a double or triple flash mode also increases the effectiveness of the signal. There were significant interactions between the alert variables used. The difference in perceived hazard levels for the colours blue and yellow were statistically non significant, but blue was more effective in conveying hazard message than yellow at the high flash rates. When accompanied with auditory alarms, blue and yellow were perceived to convey the same perception level of hazard as red without auditory alarms. The effect of colour on perceived hazard was also found to vary with flash mode. As compared to either visual signal alone or a visual signal with other types of acoustic alarms, a siren type of auditory alarm was found more effective for eliciting perception of hazards. There was evidence that presenting alerting signal in triple-flash mode and at high flash rate could be annoying and might not help improving hazard awareness. 相似文献
72.
Annie J. Morris Joseph J. Donovan Michael Strager 《Environmental Modeling and Assessment》2009,14(1):73-84
Streamflow values are commonly synthesized for locations where flow measurement stations are lacking or where only intermittent
measurements are available. In an Appalachian Mountains dataset comprised of 29 watersheds, the most appropriate among geomorphic,
geologic, and hydrogeologic datasets were selected for use in prediction of streamflow at watershed scale. A statistical model
was developed using principal components analysis (PCA) and cluster analysis (CA) for. Using CA on variables derived from
the PCA, an optimum set of variables was derived for predicting streamflow. Results indicate there are two categories of watersheds
in the study area. The first is strongly correlated with climatic variables (precipitation, temperature, elevation, and groundwater
recharge). The second is strongly correlated with two geomorphic variables (watershed slope and percentage of forested area).
The spatial distribution of cluster classifications shows that watersheds dominated by the climatic component are located
along the Allegheny Front while watersheds dominated by the geomorphic component are located in the Allegheny Plateau and
Valley and Ridge physiographic provinces. These variations between the Allegheny Plateau and Valley and Ridge physiographic
provinces suggest that, to accurately model streamflow, modeling needs be done based on natural physiographic boundaries rather
than political boundaries. In this physiographic setting, elevation seems to be a major control. 相似文献
73.
Meta-analysis of environmental contamination by phthalates 总被引:1,自引:0,他引:1
Alexandre Bergé Mathieu Cladière Johnny Gasperi Annie Coursimault Bruno Tassin Régis Moilleron 《Environmental science and pollution research international》2013,20(11):8057-8076
Phthalate acid esters (PAE), commonly named phthalates, are toxics classified as endocrine-disrupting compounds; they are primarily used as additives to improve the flexibility in polyvinyl chloride. Many studies have reported the occurrence of phthalates in different environmental matrices; however, none of these studies has yet established a complete overview for those compounds in the water cycle within an urban environment. This review summarizes PAE concentrations for all environmental media throughout the water cycle, from atmosphere to receiving waters. Once the occurrences of compounds have been evaluated for each environmental compartment (urban wastewater, wastewater treatment plants, atmosphere, and the natural environment), we reviewed data in order to identify the fate of PAE in the environment and establish whether geographical and historical trends exist. Indeed, geographical and historical trends appear between Europe and other countries such as USA/Canada and China, however they remain location dependent. This study aimed at identifying both the correlations existing between environmental compartments and the processes influencing the fate and transport of these contaminants into the environment. In Europe, the concentrations measured in waterways today represent the background level of contamination, which provides evidence of a past diffuse pollution. In contrast, an increasing trend has actually been observed for developing countries, especially for China. 相似文献
74.
George A. Allen Jung-a Annie Oh Petros Koutrakis Costas Sioutas 《Journal of the Air & Waste Management Association (1995)》2013,63(9):133-141
ABSTRACT Several recent studies have shown associations between ambient concentrations of particle mass (PM) and rates of morbidity and mortality in the general population. These studies have raised the issue of quality of coarse mass (CM, PM between 2.5 and 10 µm) data used for these purposes. CM data may have precision three or more times worse than the associated PM 2.5 or PM10 data, depending on the measurement method, PM 2.5 to PM 10 ratios, and CM concentrations. CM is measured either as the difference between collocated PM10 and PM2.5 samplers or more directly with a dichotomous (virtual impactor) sampler. CM precision for the difference method is degraded due to the increased errors inherent with using the difference between two independent measurements, as well as the high PM2.5 to PM10 ratios (and low CM concentrations) typical of the eastern United States. The dichotomous sampler (dichot) makes a more direct measurement of CM, but there is a potential for significant postexposure loss of particles from unoiled CM dichot filters, as well as uncertainties in the dichot’s CM channel enrichment factor. Compared to the dichot, low-volume inertial impactor samplers such as the Harvard Impactor (HI) or PM2.5 Federal Reference Method (FRM) are simpler to operate and maintain, provide sharper cut points, and do not require oiled filters to prevent loss of CM from the filter during transport. With the recent interest in CM spatial and temporal variability with respect to PM health effects, we have developed modifications to the HI PM method to provide measurements of 24-hour PM with estimated CM precision of better than 5% CV and r2 higher than 0.95, primarily by lowering field blank variability and increasing gravimetric analytical precision. These high-precision PM techniques are not limited to the HI sampler; they can also be applied to the PM2.5 FRM sampler. The measurement methods described here can be applied to future PM studies to avoid the potential problems with exposure assessment caused by CM measurements that have poor precision. 相似文献
75.
PROBLEM: This paper addresses the effects of driver factors and sign design features on the comprehensibility of traffic signs. METHODS: A survey was designed to capture subjects' personal particulars, ratings on sign features, and comprehension scores, and then administered to 109 Hong Kong full driving license holders. RESULTS: Years with driving license and education level were significant predictors of sign comprehensibility. Contrary to expectation, the driver factors of age group, years of active driving, hours of driving, last time driving, driving frequency, and non-local driving experience had no effect on comprehension performance. Sign familiarity was correlated with comprehension score for licensed drivers, whereas sign concreteness, simplicity, and meaningfulness were not. IMPACT ON INDUSTRY: The results of this study provide useful guidelines for designing more user-friendly traffic signs in the future. It identified particular driver groups who lacked good understanding of traffic signs, and this information may assist the relevant organizations to better allocate traffic training resources, and better target future studies of traffic sign comprehension. 相似文献
76.
Annie‐Claude Parent François Anctil Véronique Cantin Marie‐Amélie Boucher 《Journal of the American Water Resources Association》2008,44(3):679-688
Abstract: Snowmelt largely affects runoff in watersheds in Nordic countries. Neural networks (NN) are particularly attractive for streamflow forecasting whereas they rely at least on daily streamflow and precipitation observations. The selection of pertinent model inputs is a major concern in NNs implementation. This study investigates performance of auxiliary NN inputs that allow short‐term streamflow forecasting without resorting to a deterministic snowmelt routine. A case study is presented for the Rivière des Anglais watershed (700 km2) located in Southern Québec, Canada. Streamflow (Q), precipitations (rain R and snow S, or total P), temperature (T) and snow lying (A) observations, combined with climatic and snowmelt proxy data, including snowmelt flow (QSM) obtained from a deterministic model, were tested. NN implemented with antecedent Q and R produced the largest gains in performance. Introducing increments of A and T to the NNs further improved the performance. Long‐term averages, seasonal data, and QSM failed to improve the networks. 相似文献
77.
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The present study examined the mode and timing of reproduction of poorly understood deep-water octocorals and the environmental
factors that may influence their reproductive patterns. Data on reproductive characteristics of the octocoral Drifa glomerata (Alcyonacea: Nephtheidae) collected between 2004 and 2007 at ca. 100–330 m depth off Newfoundland and Labrador (eastern Canada)
were compared among years, months and depth ranges. No male gonad was ever observed during the study. The ratio of fertile
colonies possessing large pinkish polyps with oocytes/planulae was >50% throughout the year. The number of brooded planula
larvae within a single fertile polyp varied between 1 and 10 for a total of approximately 40–3,000 in a whole colony. The
size of oocytes and/or planulae was consistently greater in the polyps than in the branchlets, indicating that the development
pathway of oocytes to planulae is from the branchlets to the polyps. Although larval production seemed to persist year round,
the onset of major planulation events occurred in December–January of two consecutive years, when large mature planulae were
released in correlation with the first increase of photoperiod and maximum temperature at 150 m. A second peak in planulation
between April and early June followed the phytoplankton bloom. Seasonal trends were more apparent in colonies from <200 m,
and the planula index varied among sampling depths and years. Larval release in a live colony under laboratory conditions
occurred between January and June 2008, closely following predictions based on field samples. 相似文献