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701.
Lawrence J.H. Schulze Edward Stanton Anupam Patel Maurizio Cheli 《International journal of occupational safety and ergonomics》2013,19(1-2):31-40
Hand cranks are used in a variety of industries to actuate valves and in other gear-operated applications. In order to evaluate these types of operations and their compatibility with operator strength capabilities, a rotational dynamometer was used to measure torque production capability of operators using a hand crank at different heights and angles (with respect to the coronal plane). The tests were conducted for both clockwise and counterclockwise rotations using the dominant arm of each test participant. A total of 18 tests were completed by each of five male right-handed test participants. A 0° declination angle, counterclockwise operation, and both 40.65 cm and 60.96 cm heights were found to be associated with the greatest torque production capabilities. 相似文献
702.
Lawrence J.H. Schulze David Goldstein Anupam Patel Edward Stanton James Woods 《International journal of occupational safety and ergonomics》2013,19(3-4):109-118
Opening and closing valves in industrial facilities often requires operators to use bars and wrenches as levers (cheaters) in order to overcome initial actuation forces. In order to determine more appropriate operational specifications, the maximum torque production capability was measured when 12 male participants used 4 different valve handwheels at 3 different heights and 2 different angles (in relationship to the coronal plane). The results indicate that the participants produced significantly greater torque when the largest of the 4 wheels (40.6 cm diameter) was used than when the medium (22.9 cm), small (20.3 cm), and handled (17.8 cm) handwheels were used. Although the main effect of heights was found to be statistically significant, post-hoc analyses between the heights found them to be, essentially, equal. In addition, the vertical and horizontal wheel orientations were not found to be different. The results are applicable to all industries where handwheels are used and applicable to valve manufacturers for designing operational torque specifications below the values found in this study. 相似文献
703.
Al-Atta Ammar Sher Farooq Hazafa Abu Zafar Ayesha Iqbal Hafiz M. N. Karahmet Emina Lester Edward 《Environmental science and pollution research international》2022,29(41):61896-61904
Environmental Science and Pollution Research - During the past few decades, the treatment of hazardous waste and toxic phenolic compounds has become a major issue in the pharmaceutical, gas/oil,... 相似文献
704.
Urbanization often alters catchment storm responses, with a broad range of potentially significant environmental and engineering consequences. At a practical, site-specific management level, efficient and effective assessment and control of such downstream impacts requires a technical capability to rapidly identify development-induced storm hydrograph changes. The method should also speak specifically to alteration of internal watershed dynamics, require few resources to implement, and provide results that are intuitively accessible to all watershed stakeholders. In this short paper, we propose a potential method which might satisfy these criteria. Our emphasis lies upon the integration of existing concepts to provide tools for pragmatic, relatively low-cost environmental monitoring and management. The procedure involves calibration of rainfall-runoff time-series models in each of several successive time windows, which sample varying degrees of watershed urbanization. As implemented here, only precipitation and stream discharge or stage data are required. The readily generated unit impulse response functions of these time-series models might then provide a mathematically formal, yet visually based and intuitive, representation of changes in watershed storm response. Nominally, the empirical response functions capture such changes as soon as they occur, and the assessments of storm hydrograph alteration are independent of variability in meteorological forcing. We provide a preliminary example of how the technique may be applied using a low-order linear ARX model. The technique may offer a fresh perspective on such watershed management issues, and potentially also several advantages over existing approaches. Substantial further testing is required before attempting to apply the concept as a practical environmental management technique; some possible directions for additional work are suggested. 相似文献
705.
Modeling and interpreting bioavailability of organic contaminant mixtures in subsurface environments
Bioavailability often controls the fate of organic contaminants in surface and subsurface aquatic environments. Bioavailability can be limited by sorption, mass transfer, and intrinsic biodegradation potential and can be further altered by the presence of other compounds. This paper reviews current perspectives on the processes influencing subsurface contaminant bioavailability, how these processes are modeled, and how the relative role of the various processes can be assessed through bioavailability indices. Although these processes are increasingly well understood, the use of sophisticated models and indices often are precluded by an inability to estimate the many parameters that are associated with complex models. Nonetheless, the proper representation of sorption, mass transfer, biodegradation, and co-solute effects can be critical in predicting bio-attenuation. The influence of these processes on contaminant fate is illustrated with numerical simulations for the simultaneous degradation of toluene (growth substrate) and trichloroethylene (nongrowth cometabolite) in hypothetical, aerobic, solid-water systems. The results show how the relative impacts on contaminant fate of the model's various component processes depends upon system conditions, including co-solute concentrations. Slow biodegradation rates increase the inhibition effects of a cometabolite and suppress the rate enhancement effects of a growth substrate. Irrespective of co-solute effects, contaminant fate is less sensitive to biodegradation processes in systems with strong sorption and slow desorption rates. Bioavailability indices can be used to relate these findings and to help identify appropriate modeling simplifications. In general, however, there remains a need to redefine such indices in order that bioavailability concepts can be better incorporated into site characterization, remediation design, and regulatory oversight. 相似文献
706.
Degradation of chlorophenols in aqueous media using UV XeBr excilamp in a flow-through reactor 总被引:1,自引:0,他引:1
2-Chlorophenol (2-CP), 4-chlorophenol (4-CP) and 2,4-dichlorophenol (2,4-DCP) at initial concentrations of 10, 20, 50 and 100mg l(-1) were degraded in aqueous media by direct UV photolysis using dielectric barrier discharge XeBr( *) excilamp (283nm) in a flow-through photoreactor. The pseudo-first order rate constants were highest and half-life times were lowest for 4-CP. The rates of photolysis under the experimental conditions increased in the order: 2-CP<2,4-DCP<4-CP. The intermediates of photolysis were identified by GC-MS and HPLC. The evolution of hydroquinone and p-benzoquinone as major intermediates of 4-CP photolysis was monitored. 相似文献
707.
Significance of dredging on sediment denitrification in Meiliang Bay, China: A year long simulation study 总被引:10,自引:1,他引:10
Jicheng Zhong Chengxin Fan Lu Zhang Edward Hall Shiming Ding Bao Li Guofeng Liu 《环境科学学报(英文版)》2010,22(1):68-75
An experiment for studying the effects of sediment dredging on denitrification in sediments was carried out through a one-year incubation of undredged (control) and dredged cores in laboratory. Dredging the upper 30 cm of sediment can significantly affect physico-chemical characteristics of sediments. Less degradation of organic matter in the dredged sediments was found during the experiment. Denitrification rates in the sediments were estimated by the acetylene blockage technique, and ranged from 21.6 to 102.7 nmol N2/(g dry weight (dw)·hr) for the undredged sediment and from 6.9 to 26.9 nmol N2/(g dw·hr) for dredged sediments. The denitrification rates in the undredged sediments were markedly higher (p0.05) than those in the dredged sediments throughout the incubation, with the exception of February 2006. The importance of various environmental factors on denitrification was assessed, which indicated that denitrification was regulated by temperature. Nitrate was probably the key factor limiting denitrification in both undredged and dredged sediments. Organic carbon played some role in determining the denitrification rates in the dredged sediments, but not in the undredged sediments. Sediment dredging influenced the mineralization of organic matter and denitrification in the sediment; and therefore changed the pattern of inherent cycling of nitrogen. 相似文献
708.
Chiou-Shuang Yan An-Min Chung Edward C Koziara Andrew G Verzilli 《Journal of Environmental Economics and Management》1975,2(1):60-68
The purpose of this study was to ascertain, through the use of an input-output model, the impact of air pollution control costs on income groups in the Philadelphia Region. The range of increases in consumption expenditure was found to be fairly narrow, with the middle-income group bearing the largest increase (2.9%) and the highest and lowest groups slightly lower increases (about 2%). This finding lends support to the proposition that all income groups would probably share the costs of control equally, which leads to a slightly regressive effect on income distribution. The sharing of the region's air quality costs by other areas was also analyzed. 相似文献
709.
Tax-exempt financing of industrial pollution control equipment has increased rapidly in recent months. This method of subsidizing pollution abatement is known to be highly inefficient. If tax-exempt industrial revenue bonds were replaced by a more efficient subsidy the net financial benefits to polluting industries could probably be about doubled without any extra cost to American taxpayers. Increased utilization of an inefficient subsidy device and the international energy crisis make this a propitious time for tax experts and economists to re-examine the question, should industrial pollution control investments be subsidized? 相似文献
710.
Effects of Increasing Urbanization on the Ecological Integrity of Open Space Preserves 总被引:3,自引:0,他引:3
This article analyzes the effects of increasing urbanization on open space preserves within the metropolitan area of Phoenix,
Arizona, USA. Time series analysis is used in 10-year increments over 40 years to study urban landscape change. Three landscape
metrics—(1) matrix utility (measures intensity of adjacent land uses), (2) isolation (measures distances to other open space
patches), and (3) connectivity (measures physical links to other open space patches and corridors)—are used to assess changes
in landscape patterns and serve as indicators of urban ecological integrity of the open space preserves. Results show that
in the case of both open space preserves, general decline in indicators of urban ecological integrity was evident. The matrix
utility analysis demonstrated that increasing intensity of land uses adjacent to preserve is likely to increase edge effects,
reducing the habitat value of interior or core habitat areas. Isolation analysis showed that both preserves have experienced
increasing isolation from other open space elements over time. Also, connectivity analysis indicated that terrestrial connections
to other open space elements have also deteriorated. Conclusions of this research demonstrate that while preservation of natural
areas as open space is important in an urban context, intense development of surrounding areas reduces the urban ecological
integrity significantly. 相似文献