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991.
The workplace has become the locus of many stress management and stress reduction interventions. However, little attention has focused on how worksite factors affect the implementation and impact of such interventions. In this paper, we investigate the effect of new versus traditional industrial relations practices on the impact of a worksite stress reduction program in a manufacturing setting. More specifically, a participatory action research (PAR) stress project is described and evaluated in two different labor–management relations contexts. One organization is characterized by the emerging ’new‘ industrial relations system where labor–management relations incorporate elements of joint problem-solving. The other organization has a more traditional approach where labor–management relations are formally adversarial. Results indicate that the labor–management relations context did influence the impact of the stress project. Involvement in the PAR stress project enhanced employee participation in decision-making in both contexts. However, involvement in the stress project enhanced employees' perceptions of the climate for participation only in the organization with more cooperative industrial relations. Increases in coworker support and decreases in depressive symptoms were associated with involvement in the PAR stress project in the organization with more adversarial industrial relations.  相似文献   
992.
993.
994.
Where natural drainage is inadequate for keeping the water table below the root zone of the crops being grown, drains are often employed to control water table levels. Such drains are commonly installed in parallel lines at depths and spacings adapted to the needs of the area. Formulas used for determining drain spacings are generally based upon Dupuit-Forchheimer concepts. These developments postulate a saturated, permeable aquifer underlying the irrigated area and an impermeable barrier underlying the aquifer. The basic differential equation expresses the requirement that the flow out through the sides of a vertical column of infinitesmal cross sectional area must be supplied by a corresponding drop of the water table at the top of the column. If variations of transmissivity due to variations of water table level are taken into account the second order differential equation obtained is nonlinear. To avoid the mathematical difficulties posed by this nonlinearity it is customary to neglect the effects of changes of transmissivity due to changes of water table levels. This imposes a restriction that the formulas derived from these linearized differential equations suffer a loss of accuracy if the change of water table levels becomes a considerable portion of the initial saturated depth. Offsetting these difficulties is the tactical advantage that the linearized differential equations are of types long studied in older developments concerned with conduction of heat in solids. The advantages conferred by the possibilities for exploiting the results of investigations in the older discipline are many. An alternative approach is based upon a requirement that there can be no accumulation of water in any elementary cubical volume located in the zone of complete saturation below the water table. The differential equation obtained on this basis, if the aquifer is homogeneous and isotropic, is the one which bears the name of Laplace. It will be the purpose of this paper to explore the possibilities afforded by this approach for evaluating the flow to parallel drains and to compare the results with those obtainable by the Dupuit-Forchheimer method.  相似文献   
995.
Many important groundwater aquifers cross state and national boundaries. The flow of water in these aquifers is not influenced by the boundaries but may be materially influenced by mans activities on one or both sides of a boundary. Interstate and international problems may develop because of excessive groundwater lowering on one side of a boundary affecting water users on the opposite side of the line. Similarly, intensive groundwater development along a surface stream may influence the amount of surface water that flows across a boundary. A third type of problem may develop when pumping on one side of the boundary induces poor quality water into an aquifer on the other side of the boundary. Several specific interstate and international aquifer problems are briefly described.  相似文献   
996.
ABSTRACT. The ability to replicate storms on a rainfall simulator over an iconic watershed model permits the study of the effectiveness of dams of different sizes and locations in reducing flood peaks. This study empirically confirms that, when storms uniformly and completely cover the watershed, large dams are nearly twice as effective as a network of small and medium dams in reducing the flood.  相似文献   
997.
Since the publication of Rachel Carson's Silent Spring in 1962 there has been a rapidly growing public concern over widespread contamination of the environment with hazardous wastes. In recent years scientific findings on the ecological effects of various hazardous substances have posed several important questions. What exactly are hazardous wastes? Can these substances be disposed of in a technically feasible, economical, and safe way with assurance that they have been permanently eliminated from the ecosystem? What compositional alterations or movements of the hazardous wastes occur in water, soil, or air systems? What effect will these wastes have on the water, soil, or air systems? What effect will these wastes have on the water, soil, or air properties? Consequently, a University of Louisville study has developed a relevant definition of hazardous wastes for the Environmental Engineering profession together with priority of concern rating systems to delineate the degree of environmental impact imposed on a total ecosystem by a hazardous waste and the feasibility of disposing of hazardous substances at specific landfill sites. It is felt that refinements of the priority of concern rating systems offered here may provide a sound basis from which procedural decisions may be structured to establish future national hazardous waste disposal sites.  相似文献   
998.
ABSTRACT. Theoretical and practical results are summarized for a study to determine optimal water resource allocation in a proposed water conservancy district. The area of this district, which covers several river basins, contains a large number of existing and proposed facilities such as reservoirs and diversions. The operation of all of these facilities was to be determined along with the sizing of the proposed facilities in order to optimize given objective functions. Related efforts in optimal river basin utilization were surveyed, and linear programming was selected as an expedient optimization technique. The problem is formulated by identifying time stages which together constitute a repetitive cycle such as a year. With these stages, it is possible to associate operational and capacity variables with network components, which are branches and nodes. Objective functions are assembled for the component variables. Constraint equations are written in terms of the variables to reflect network nodal continuity, capacity restrictions, and adjudications such as water rights. A numerical example is considered in which the existing and proposed facilities are aggregated to produce a small, tractable number of facilities. This paper examines the example results and suggests future improvements for models of this type.  相似文献   
999.
ABSTRACT There are several possible ways in which wastewater from municipalities may be reclaimed and reused so as to minimize the need for imported water in North Central Texas. The rationale for reuse is enhanced by the fact that new water quality requirements in the Trinity River system will necessitate a very high degree of treatment at municipal sewage plants, just for discharge to surface streams. The largest potential market for municipal effluent is the steam-electric power industry. Within the next decade the generating capacity for electric power in North Central Texas will have to be more than doubled to meet increasing demand. Adequate supplies of condenser cooling water for such expansion will be difficult to obtain and assure. New large power stations might advantageously be located adjacent to municipal wastewater treatment plants, to utilize effluent as make-up water for cooling towers. Experience elsewhere has shown that well-treated wastewater can be used for cooling tower make-up with a minimum of trouble, with a considerable saving in overall cost, and with conservation of pristine water for other uses.  相似文献   
1000.
Three fundamental concepts linking drainage basin characteristics, stream behavior, and management of watersheds are deduced from field data and observations. An electrical analogy of a watershed clarifies definitions and broadens understanding of this complex natural resource. The three basic principles deal with (1) the interrelationships of watershed morphology, constitution, and appearance; (2) the nature of the control man can exert over runoff-influencing forces, and (3) the efficiency of watershed management efforts. Recognition of these principles can assist educators, managers, planners and researchers to more fully inform students and to more effectively guide and evaluate management decisions.  相似文献   
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