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31.
Abstract

This paper analyzes the transformation of river basin management in South Africa by focusing on the political processes involved in the creation of new water management bodies and irrigation infrastructure in the Lower Komati sub-basin. Institutional reform is described and analyzed in terms of the collaboration theory of Gray (1985). Attention is paid to the absence of mutual collaboration in the water domain through the analysis of three phases that are characteristic of collaborative management: problem setting, direction setting, and structuring. The perceptions and strategies of stakeholders in the change process are informed by the skewed access to land and water, the protracted struggle for redress of historical inequities, the quest for autonomy in water management by commercial farmers, and large political power differentials. This has resulted in differential access to decision making and political influence and in the materialization of these skewed relations in water control technology. The reluctance of stakeholders to explicitly recognize their interdependence and the role of the state as the convener of the change process has hampered the emergence of a shared appreciation of the problems in the water domain. Despite efforts by government to move towards equitable and inclusive water management, little redress of past inequities has taken place, and the majority of small farmers are uninformed and excluded from the change process. This suggests that the proposed Catchment Management Agency will not be representative nor attain equitable water management unless a well-conceived redistribution of water entitlements and land rights is carried out as part of an encompassing program to strengthen political democracy.  相似文献   
32.
A valuation scenario was designed using a contingent-valuation approach and presented to decision makers in business firms in Kenya’s Lake Naivasha basin to test how applicable a water fund might be as a potential financing mechanism for a payment for water-related ecosystem services scheme. The findings indicate that measuring a firm’s willingness to invest in ecosystem services could help determine whether a firm would invest and engage with other stakeholders to pool their investments in ecosystem services. Linking the institutional decision-making behaviour of a firm and its willingness to invest in a water fund is the novelty of this article.  相似文献   
33.
Flood Risk Management in Flanders: Past Developments and Future Challenges   总被引:1,自引:1,他引:0  
This paper presents the state of the art of flood risk management in Flanders, a low-lying region in the northern part of Belgium which is vulnerable to flooding. Possible flood hazard sources are not only the many rivers which pass through the Flemish inland, but also the North Sea, which is sensitive to the predicted sea level rise and which can affect large parts of the Flemish coastal area. Due to the expected increase in flood risks in the 21st century, the Flemish government has changed its flood management strategy from a flood control approach to a risk-based approach. Instead of focusing on protection against a certain water level, the objective now is to assure protection against the consequences of a flood, while considering its probability. In the first part, attention is given to the reasoning and functioning of the risk-based approach. Recent improvements to the approach are discussed, as well as the GIS-implementation of the entire model. The functioning of the approach is subsequently demonstrated in two case studies. The second part of the paper discusses future challenges for the flood risk management in Flanders. The driving force behind these challenges is the European Directive on the assessment and management of flood risks, which entered into force in 2007. The Flemish implementation of the directive is discussed and situated in the European landscape. Finally, attention is given to the communication of flood risks to the general public, since the “availability” of flood risk management plans is among the requirements of the EU Floods Directive.  相似文献   
34.
Carbon fibre/epoxy rings are used as radial reinforcement for polymer bearing elements with nominal diameter 250 mm functioning under 150 MPa. Full-scale static and dynamic testing revealed no catastrophic failure for loading to 400 MPa, although there was circumferential splitting of carbon fibres at the machined top edge causing counterface wear under sliding. A combined numerical–experimental analysis was applied for design improvement with a representative small-scale qualification test on the real ring geometry, inducing additional stress concentrations compared to ASTM standards. Full-scale modelling revealed high radial–axial shear stresses (33 MPa) in non-hydrostatically loaded zones, while it increased towards 104 MPa under hydrostatic load conditions. The former is the most critical and should be simulated either on a small-scale unidirectional compression test or on a representative short beam shear test, respectively, measuring the radial–axial or radial–tangential shear strength. A relation between both small-scale states of stress was experimentally and numerically studied, experiencing that the composite ring has lower radial–tangential shear stress compared to radial–axial shear stress as a different hydrostatic stress state is observed in the bulk of the composite ring. As a compressive test is however more difficult to perform than a short-beam-shear test, a representative design criterion for shear fracture is determined from failure at 27 kN normal load in a short-beam-shear test. Finally, fracture is avoided by optimising the cross-sectional geometry of the composite reinforcing ring and close control of the processing parameters.  相似文献   
35.
A back propagation (BP) neural network (NN) method has been developed to predict the stability of RNA/DNA duplex. Calculated Tm of hybrid formation with the present parameters fits the experimental values within reasonable errors (AD=1.2887 K, SEP=1.782, R2=0.9673 for NN1; AD=2.1388 K, SEP=3.506, R2=0.8889 for NN2). And it has the advantage that the determinations of thermodynamic parameters (TP) are not needed.  相似文献   
36.
Physarum polycephalum, a true slime mould, is a primitive, unicellular organism that creates networks to transport nutrients while foraging. The design of these natural networks proved to be advanced, e.g. the slime mould was able to find the shortest path through a maze. The underlying principles of this design have been mathematically modelled in literature. As in real life the slime mould can design fault tolerant networks, its principles can be applied to the design of man-made networks. In this paper, an existing model and algorithm are adapted and extended with stimulation and migration mechanisms which encourage formation of alternative paths, optimize edge positioning and allow for automated design. The extended model can then be used to better design fault tolerant networks. The extended algorithm is applied to several national and international network configurations. Results show that the extensions allow the model to capture the fault tolerance requirements more accurately. The resulting extended algorithm overcomes weaknesses in geometric graph design and can be used to design fault tolerant networks such as telecommunication networks with varying fault tolerance requirements.  相似文献   
37.
In this paper, we discuss the resource–constrained project scheduling problem with discounted cash flows. We introduce a new schedule construction technique which moves sets of activities to improve the project net present value and consists of two steps. In particular, the inclusion of individual activities into sets, which are then moved together, is crucial in both steps. The first step groups the activities based on the predecessors and successors in the project network, and adds these activities to a set based on their finish time and cash flow. The second step on the contrary does so based on the neighbouring activities in the schedule, which may but need not include precedence related activities. The proposed scheduling method is implemented in a genetic algorithm metaheuristic and we employ a penalty function to improve the algorithm’s feasibility with respect to a tight deadline. All steps of the proposed solution methodology are tested in detail and an extensive computational experiment shows that our results are competitive with existing work.  相似文献   
38.
Severe traffic congestion and growing ecological consciousness have led to the rise of alternative transportation systems. Ride sharing is one such alternative in which drivers and passengers with similar time schedules and travel plans are matched. For this service to be effective, a large number of users are required to increase the probability of finding suitable travel partners. The present paper proposes a late acceptance metaheuristic to decide which users act as drivers and to construct their routes. The underlying optimization model allows passengers to walk to/from alternative pickup/drop‐off locations so as to further exploit user flexibility. A computational study quantifies the impact of different types of participant flexibility on CO2 emissions. These insights can inform and support policymakers in organizing effective ride‐sharing systems.  相似文献   
39.
In this paper the Virtual Private Ad Hoc Networking (VPAN) platform is introduced as an integrated networking solution for many applications that require secure transparent continuous connectivity using heterogeneous devices and network technologies. This is done by creating a virtual logical self-organizing network on top of existing network technologies reducing complexity and maintaining session continuity right from the start. One of the most interesting applications relies in the field of emergency communication with its specific needs which will be discussed in this paper and matched in detail against the architecture and features of the VPAN platform. The concept and dynamics are demonstrated and evaluated with measurements done on real hardware.  相似文献   
40.
Due to license restrictions and installation issues, it is often not feasible to experiment with software without making substantial investments. Especially in the case of legacy tools, it turns out that even free software is often too costly (i.e., time-consuming) to be installed for evaluating the quality of a research contribution. After organizing a series of events related to software modeling, we have constructed (and started to use) SHARE, a system for sharing practically any type of software artifact to reviewers and to other participants who have very limited time available. The system relies on cloud-computing technologies to provide online access to interactive environments containing all the tools, documentation, input and output models to reproduce alleged research results. The system also enables one to clone such an environment and add additional models or tools in order to extend a contribution or pinpoint a problem. In retrospect, we observe that the approach is not limited to software modeling and SHARE is in fact gaining acceptance in other fields already.  相似文献   
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