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1.
ABSTRACT: Land, water, labor, and capital are optimally allocated to crops on a farm, using a procedure that also relates to irrigation frequency and level of improvement in the irrigation system. The procedure is based on formulating outputs and expenditures as well as the functions of irrigation frequency-water and yield. The Generalized Geometric Programming is used to solve the objective function as nonlinear equations are involved.  相似文献   

2.
The general intervention model is applied to hydrologic and meteorologjc time series from the Canadian Arctic. The authors show how the model is able to account for environmental interventions, missing observations in the data, changes in data collection procedures, the effects of external inputs, as well as seasonality and autocorrelation. Methods for identifying transfer functions by making use of a physical understanding of the processes involved are demonstrated and sample applications of the general intervention model to Arctic data are shown.  相似文献   

3.
ABSTRACT. The problem of modeling and control of water pollution is considered. A general mathematical model, where the pollution effluent is discharged directly into the river, into the lake, or into a bypass pipe leading to an advanced Waste Water Treatment (AWT) plant, is developed. The Water Resource System (WRS) under consideration is decomposed into N subsystems. The pollution effluent input vector to each subsystem includes the water quantity and different water characteristics such as BOD, DO, pH, conductivity, temperature, algae, phosphates, nitrates, etc. Treatment cost functions and quality transition functions as well as system model constraints are introduced, where all functions can be nonlinear. A system Lagrangian is formed to incorporate the system constraints and coupling. The Lagrangian is decomposed into N independent subsystems, and a two level optimization methodology is introduced. Each subsystem is independently and separately minimized at the first level assuming known Lagrange multipliers. At the second level, the total Lagrangian is maximized with respect to the Lagrange multipliers using optimal values for effluent inputs from all subsystems obtained from the first level. Economic interpretation on the Lagrange multipliers reveals that they are merely prices imposed by the central authority (second level) for the pollution caused by the subsystems. Advantages of the multilevel approach are discussed.  相似文献   

4.
Agricultural water management is a complex decision-making problem involving multiple criteria of different nature as well as multiple decision agents with different interests. To handle this multiplicity of objectives and interests a pragmatic approach based on compromise programming is proposed in this paper. The methodology is applied to an agricultural water management problem in Tauste, Spain. Public, environmentalist and private decision makers are considered. The approach proposed reveals itself as a pragmatic alternative to other approaches based on aggregate utility functions with very sound theoretical underpinnings but with few possibilities of actually being put into practice.  相似文献   

5.
Structural changes in agriculture and urbanisation affect land management regimes and local landscape functions. Studying the new functions of land is as relevant as the owners' land management decisions, the replacement of farming with different activities and land uses may impact not only the local landscape's functions but also, in the long run, its structure and the environment. Drawing on a detailed case study in Tuscany based on qualitative interviews with landowners and on the understanding of the socio-economic context, this article analyses landowners' attitudes towards land property and farming in relation to individual motives as well as to local and supra-local contexts. Five relational typologies of landowners are identified: pure farmers, amenity farmers, land developers, land-with-house owners and house-with-land owners. Diverse trends – such as particular farmers’ attitudes towards land development, or the emerging role of non-professional farmers in land management – are found to raise challenges related to rural land planning and management.  相似文献   

6.
7.
三级SBR法除磷脱氮研究   总被引:2,自引:0,他引:2  
基于除磷脱氮的原理和环境要求提出三级SBR法的污水处理工艺。特点是将具有硝化、聚磷和去碳功能的细菌种群分别控制在三级反应器中以利于各类菌群能优势生长。与单级处理系统比较不仅提高效率并可以减少能耗,节约碳源。  相似文献   

8.
湖泊健康评价指标体系及评价方法初探   总被引:2,自引:0,他引:2  
李灿  李永  李嘉 《四川环境》2011,30(2):71-75
湖泊健康评价是进行湖泊监测和管理的基础。丰富了湖泊生态系统健康的概念,指出其应当考虑湖泊的各种服务功能。以湖泊生态系统健康概念为基础,构建了湖泊健康评价指标体系,给出16个综合评价指标及各指标评分方法。以四川大学明远湖为例,采用层次分析法(AHP)计算各指标权重,对其进行健康评价,得出健康综合指数为3.55,表明整个湖泊处于"较健康"状态,分析了影响湖泊健康状态的疾病因子及湖泊的生态修复方法。  相似文献   

9.
10.
We reviewed the scientific literature on non‐floodplain wetlands (NFWs), freshwater wetlands typically located distal to riparian and floodplain systems, to determine hydrological, physical, and chemical functioning and stream and river network connectivity. We assayed the literature for source, sink, lag, and transformation functions, as well as factors affecting connectivity. We determined NFWs are important landscape components, hydrologically, physically, and chemically affecting downstream aquatic systems. NFWs are hydrologic and chemical sources for other waters, hydrologically connecting across long distances and contributing compounds such as methylated mercury and dissolved organic matter. NFWs reduced flood peaks and maintained baseflows in stream and river networks through hydrologic lag and sink functions, and sequestered or assimilated substantial nutrient inputs through chemical sink and transformative functions. Landscape‐scale connectivity of NFWs affects water and material fluxes to downstream river networks, substantially modifying the characteristics and function of downstream waters. Many factors determine the effects of NFW hydrological, physical, and chemical functions on downstream systems, and additional research quantifying these factors and impacts is warranted. We conclude NFWs are hydrologically, chemically, and physically interconnected with stream and river networks though this connectivity varies in frequency, duration, magnitude, and timing.  相似文献   

11.
A groundwater hydraulic management model is used to identify the optimal strategy for allocating limited fresh-water supplies and containing wastes in a hypothetical aquifer affected by brine contamination from surface disposal ponds. The present cost of pumping from a network of potential supply and interception wells is minimized over a five-year planning period, subject to a set of hydraulic, institutional, and legal constraints. Hydraulic constraints are formulated using linear systems theory to describe drawdown and velocity variables as linear functions of supply and interception well discharge decision variables. Successful validation of the optimal management strategy suggests that the model formulation can feasibly be applied to define management options for locally contaminated aquifer systems which are used to fulfill fresh-water demands.  相似文献   

12.
Interbasin water transfer is often accomplished by tunnel systems discharging the water from subreservoirs into a main reservoir. Such a system involving an arbitrary number of reservoirs is considered and an iterative method is developed for the determination of all tunnel sizes giving minimum total cost of the system when the individual discharges from the subreservoirs and elevations of the water surfaces of all reservoirs are known. It is assumed that all tunnels are flowing full. Influence of average construction cost per unit volume as well as tunnel roughness and cross-sectional shape is taken into consideration. The corresponding computer program for the general case is presented. The method may also be adapted to pipe systems, open channel systems, or combined systems by introduction of the proper cost functions for these conduits.  相似文献   

13.
ABSTRACT: Generally a difference exists between the horizontal planar area of a watershed as measured on a map and the actual surface area. A technique is presented, utilizing a topographic map, for computing the difference in the two areas as well as yielding a prediction of the actual surface area. Spatial variations in the magnitude of the difference in the two areas for small local sites over the watershed are displayed on computer generated maps. The technique is also used to adjust various inventory variables on maps, such as vegetation density, to reflect actual surface coverage. This allows estimates to be made of the difference in using corrected versus uncorrected area related parameters in mathematical functions describing processes occurring in the atmosphere-surface boundary layer.  相似文献   

14.
The existing inexact optimization methods based on interval-parameter linear programming can hardly address problems where coefficients in objective functions are subject to dual uncertainties. In this study, a superiority–inferiority-based inexact fuzzy two-stage mixed-integer linear programming (SI-IFTMILP) model was developed for supporting municipal solid waste management under uncertainty. The developed SI-IFTMILP approach is capable of tackling dual uncertainties presented as fuzzy boundary intervals (FuBIs) in not only constraints, but also objective functions. Uncertainties expressed as a combination of intervals and random variables could also be explicitly reflected. An algorithm with high computational efficiency was provided to solve SI-IFTMILP. SI-IFTMILP was then applied to a long-term waste management case to demonstrate its applicability. Useful interval solutions were obtained. SI-IFTMILP could help generate dynamic facility-expansion and waste-allocation plans, as well as provide corrective actions when anticipated waste management plans are violated. It could also greatly reduce system-violation risk and enhance system robustness through examining two sets of penalties resulting from variations in fuzziness and randomness. Moreover, four possible alternative models were formulated to solve the same problem; solutions from them were then compared with those from SI-IFTMILP. The results indicate that SI-IFTMILP could provide more reliable solutions than the alternatives.  相似文献   

15.
The purpose of this paper is to conceptualize the hitherto separate domains of Cyberspace and International Relations into an integrated socio-technical system that we jointly call the cyber International Relations (Cyber-IR) system and to identify and analyze its emergent properties utilizing the methods common to science and engineering systems adapted here for the social sciences. Our work is an exploration in both theory and methodology. This paper (a) identifies the actors and functions in the core systems, Cyberspace, and IR, (b) disambiguates system boundary, (c) creates a design structure matrix (DSM), a matrix of the interdependencies among functions of actors, (d) analyzes DSM qualitatively to show multiple interdependent and heterogeneous Cyber-IR properties, and (e) analyzes quantitatively the differential importance of core functions as well as the impact of actor attributes on influence in Cyber-IR. This work forms a baseline for further understanding of the nature of the heterogeneous influences of the various actors and the various outcomes that could result from it.  相似文献   

16.
ABSTRACT: Mean monthly runoff from ungaged drainage basins that have significant snowpacks each year can be estimated quite well by assuming that the time duration between snowfall and snowmelt is the predominant factor in temporal runoff distribution. That time span is related to basin temperatures which are, in turn, functions of basin elevation and latitude. Regional hydrologic analyses of gaged basin data create regression equations for estimating runoff distribution by month. These equations then can be applied to ungaged basins. Basin latitude and mean elevation are two independent variables that can be used in estimating monthly runoff distributions.  相似文献   

17.
A notable feature of development aid since the 1960s has been a paradigm shift from centralised project planning and management to decentralised approaches. The transition from top-down to bottom-up elevates the concept of localism in project management for vulnerable groups. This change resonates well in community-based resource management schemes in privileging the locale in terms of generation of knowledge and how problems and remedies are enunciated. Localism conceptualised as devolving central-level government functions to non-state actors in social service delivery is contradictory and seems to negate state powers. This paper explores this trajectory to explicate the forms of localism and the contradictions from its multiple conceptualisations that influence energy access. Using qualitative methodology and interviews, it analyses renewable energy projects directed at poverty alleviation in rural communities in Nigeria while deploying a political ecology framework of power relations to highlight the dynamics of localism. While localism is touted as a constraint in the development process due to localism of action, the paper demonstrates its prospects and how scaling-up of operations may augur well for altering its conceptualisation and with far-reaching consequences for community sustainable energy projects.  相似文献   

18.
One key development in environmental software is the adoption of a common electronic language for exchanging EH&S data. The ANSIX12-based data management tools offer compatibility across platforms within the company as well as between different companies. The X12 syntax makes it easy for environmental managers to integrate functions more closely with either materials management or quality management systems.  相似文献   

19.
There is now an emerging sense of the scope and nature of response that can be implemented at building and neighbourhood scales to help adapt cities and urban areas to the changing climate. In comparison, the role of larger natural and semi-natural landscapes that surround and permeate cities is less well understood. Addressing this knowledge gap, this paper outlines two case studies that describe and map the flood risk management functions offered by green infrastructure landscapes situated within the Urban Mersey Basin in North West England. The case studies establish that areas potentially exposed to flooding can be located at some distance, and within different jurisdictions, from upstream areas where the flood hazard may be generated and could be moderated via functions provided by green infrastructure landscapes. This raises planning and governance challenges connected to supporting and enhancing flood risk management functions provided by green infrastructure landscapes.  相似文献   

20.
A chance-constrained linear programming model, which utilizes multiple linear decision rules and is useful for river basin planning, is used to evaluate the effects of risk and reliability on optimal reservoir design. Streamflow forecasts or predictions can be explicitly included in the linear program. The risk associated with the predictions is included in the model through the use of cumulative distribution functions (CDF) of streamflows which are conditioned on the predictions. A multiple-purpose reservoir on the Gunpowder River in Maryland is used to illustrate the effectiveness of the model. In order to provide the decision makers with complete and useful information, trade-off curves relating minimum reservoir capacity (a surrogate for dam costs), water supply and flood control targets, and the reliability of achieving the targets are developed. The trade-off curves may enhance the decision maker's ability to select the best dam capacity, considering technological and financial constraints as well as the trade-offs between targets, risks, and costs.  相似文献   

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