Multi-node protection of landscape connectivity: habitat availability and topological reachability

The selection of reserves for biodiversity conservation involves the evaluation of multiple criteria, ranging from representativeness of ecological features to anthropogenic interests and spatial configuration. Among the principal spatial attributes to be considered, connectivity has received particular emphasis in response to the escalating threat of habitat loss and fragmentation. Connectivity is an intrinsic property of networks. Consequently, we have observed the gradual development of the concept of reserve networks, enlisting also tools from the mathematical branch of network theory. Here, we first outline three key aspects of reserve selection for connectivity conservation based on network analysis. 1) It may be based on the application of topological indices, which take into consideration only the geographical position of the habitat patches, or area-weighted indices, which add a premium to larger patches. 2) It may be done through single-node analysis, where the relative importance of patches is evaluated individually, or with the more efficient multi-node analysis, where we search for the optimal group of patches that best complement each other in the role of maintaining connectivity. 3) The goal of the selection may be to avoid fragmentation of the population into isolated portions, or to ensure that reachability is maintained to all habitat patches, including peripheral sites. In previous studies, we had introduced multi-node analysis to the prioritization of reserves, using fragmentation and reachability indices, but these were limited to topology only. Here, we present an improved approach where multi-node prioritization is performed with area-weighted fragmentation. We apply it to 20 bird species in Catalonia, Spain. In comparison with single-node and/or topological fragmentation, we observed here a decentralization of the selected reserve sets: they included not only the main core population, but also secondary clusters of well-connected habitat. This may potentially bring two added advantages to the reserve network: spreading of risk, and inclusion of a wider variety of local genetic profiles. We propose combining this approach with topological reachability, to account for peripheral populations and maximize accessibility to the entire network

Reserve Site Selection in a Limited-Entry Fishery

Marine reserves are gaining attention around the world as a tool to both conserve ocean resources and improve the productivity of fisheries. Using simulation analysis, we investigate in a limited-entry fishery comprising nine subpopulations the inherent bioeconomic trade-offs associated with cost-effective designs of marine reserve networks—that is, the trade-offs between the degree of connectedness of a site and the biological and economic heterogeneity. We find in many cases that closing two low-value patches can result in larger biological gains and lower costs than closing one high-value patch. We also simulate biological productivity effects after creation of a reserve and find that under special conditions, aggregate sustainable rents are maximized with the closing of a portion of the fishable habitat. Finally, we find that the biological gains of implementing a more rationalized management system can outweigh the gains from closing multiple subpopulations under open access.fisheries; limited-entry; marine reserves; marine reserve networks

An Evolutionary Computational Approach for the Problem of Unit Commitment and Economic Dispatch in Microgrids under Several Operation Modes

In the last decades, new types of generation technologies have emerged and have been gradually integrated into the existing power systems, moving their classical architectures to distributed systems. Despite the positive features associated to this paradigm, new problems arise such as coordination and uncertainty. In this framework, microgrids constitute an effective solution to deal with the coordination and operation of these distributed energy resources. This paper proposes a Genetic Algorithm (GA) to address the combined problem of Unit Commitment (UC) and Economic Dispatch (ED). With this end, a model of a microgrid is introduced together with all the control variables and physical constraints. To optimally operate the microgrid, three operation modes are introduced. The first two attend to optimize economical and environmental factors, while the last operation mode considers the errors induced by the uncertainties in the demand forecasting. Therefore, it achieves a robust design that guarantees the power supply for different confidence levels. Finally, the algorithm was applied to an example scenario to illustrate its performance. The achieved simulation results demonstrate the validity of the proposed approach.Ministerio de Ciencia, Innovación y Universidades TEC2016-80242-PMinisterio de Economía y Competitividad PCIN-2015-043Universidad de Sevilla Programa propio de I+D+

MPA network design based on graph network theory and emergent properties of larval dispersal

Despite the recognised effectiveness of networks of Marine Protected Areas (MPAs) as a biodiversity conservation instrument, nowadays MPA network design frequently disregards the importance of connectivity patterns. In the case of sedentary marine populations, connectivity stems not only from the stochastic nature of the physical environment that affects early-life stages dispersal, but also from the spawning stock attributes that affect the reproductive output (e.g., passive eggs and larvae) and its survivorship. Early-life stages are virtually impossible to track in the ocean. Therefore, numerical ocean current simulations coupled to egg and larval Lagrangian transport models remain the most common approach for the assessment of marine larval connectivity. Inferred larval connectivity may be different depending on the type of connectivity considered; consequently, the prioritisation of sites for marine populations' conservation might also differ. Here, we introduce a framework for evaluating and designing MPA networks based on the identification of connectivity hotspots using graph theoretic analysis. We use as a case of study a network of open-access areas and MPAs, off Mallorca Island (Spain), and test its effectiveness for the protection of the painted comber Serranus scriba. Outputs from network analysis are used to: (1) identify critical areas for improving overall larval connectivity; (2) assess the impact of species' biological parameters in network connectivity; and (3) explore alternative MPA configurations to improve average network connectivity. Results demonstrate the potential of graph theory to identify non-trivial egg/larval dispersal patterns and emerging collective properties of the MPA network which are relevant for increasing protection efficiency.Comment: 8 figures, 3 tables, 1 Supplementary material (including 4 table; 3 figures and supplementary methods

FedRR: a federated resource reservation algorithm for multimedia services

The Internet is rapidly evolving towards a multimedia service delivery platform. However, existing Internet-based content delivery approaches have several disadvantages, such as the lack of Quality of Service (QoS) guarantees. Future Internet research has presented several promising ideas to solve the issues related to the current Internet, such as federations across network domains and end-to-end QoS reservations. This paper presents an architecture for the delivery of multimedia content across the Internet, based on these novel principles. It facilitates the collaboration between the stakeholders involved in the content delivery process, allowing them to set up loosely-coupled federations. More specifically, the Federated Resource Reservation (FedRR) algorithm is proposed. It identifies suitable federation partners, selects end-to-end paths between content providers and their customers, and optimally configures intermediary network and infrastructure resources in order to satisfy the requested QoS requirements and minimize delivery costs

Incentive Design and Market Evolution of Mobile User-Provided Networks

An operator-assisted user-provided network (UPN) has the potential to achieve a low cost ubiquitous Internet connectivity, without significantly increasing the network infrastructure investment. In this paper, we consider such a network where the network operator encourages some of her subscribers to operate as mobile Wi-Fi hotspots (hosts), providing Internet connectivity for other subscribers (clients). We formulate the interaction between the operator and mobile users as a two-stage game. In Stage I, the operator determines the usage-based pricing and quota-based incentive mechanism for the data usage. In Stage II, the mobile users make their decisions about whether to be a host, or a client, or not a subscriber at all. We characterize how the users' membership choices will affect each other's payoffs in Stage II, and how the operator optimizes her decision in Stage I to maximize her profit. Our theoretical and numerical results show that the operator's maximum profit increases with the user density under the proposed hybrid pricing mechanism, and the profit gain can be up to 50\% in a dense network comparing with a pricing-only approach with no incentives.Comment: This manuscript serves as the online technical report of the article published in IEEE Workshop on Smart Data Pricing (SDP), 201