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Management Scheme (management + scheme)
Kinds of Management Scheme Selected AbstractsA Risk-Cost Optimized Maintenance Strategy for Corrosion-Affected Concrete StructuresCOMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 5 2007Chun-Qing Li It is also observed that some severely deteriorated concrete structures survive for many years without maintenance. This raises the question of why and how to maintain corrosion-affected concrete structures, in particular in the climate of an increasing scarcity of resources. The present article attempts to formulate a maintenance strategy based on risk-cost optimization of a structure during its whole service life. A time-dependent reliability method is employed to determine the probability of exceeding a limit state at each phase of the service life. To facilitate practical application of the formulated maintenance strategy, an algorithm is developed and programmed in a user-friendly manner with a worked example. A merit of the proposed maintenance strategy is that models used in risk assessment for corrosion-affected concrete structures are related to some of the design criteria used by practitioners. It is found in the article that there exists an optimal number of maintenances for cracking and delamination that returns the minimum total cost for the structure in its whole life. The maintenance strategy presented in the article can help structural engineers, operators, and asset managers develop a cost-effective management scheme for corrosion-affected concrete structures. [source] The termination of the last major phase of aeolian sand movement, coastal dunefields, DenmarkEARTH SURFACE PROCESSES AND LANDFORMS, Issue 7 2006Lars B. Clemmensen Abstract Optically stimulated luminescence (OSL) dating of sand samples from stabilized (or inactive) coastal dunes in Denmark provides information on the age of the termination phase of the last major aeolian activity period. A total of 26 sand samples were taken from four different coastal dunefields around the North Sea, Skagerrak and Kattegat coasts of Denmark. The OSL dates indicate that the last major phase of aeolian activity terminated between ad 1860 and 1905. Most of the dunes examined in this study were active around 1820, during a period documented to have been very stormy. A dune management scheme started around 1792, and this no doubt was a major cause of dunefield stabilization, but an overall decline of storminess, particularly spring and summer storminess, around the end of the 19th century must also have contributed to the increasing inactivity of coastal dunes. The new OSL dates on aeolian sand movement agree well with historical data and data from topographic maps on dune movement. This agreement supports the observation from earlier work that OSL dating of recent aeolian sand movement is accurate over the last few decades to centuries. Copyright © 2005 John Wiley & Sons, Ltd. [source] Adaptive routing algorithms and buffer management in multihop metropolitan area networksEUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 3 2002Paolo Giacomazzi The present study is devoted to multihop Metropolitan Area Network architectures characterized by some buffer capacity at the nodes and routing algorithm slightly more complex than those already present in the literature. A new adaptive routing algorithm and a new buffer management scheme are presented, and their performance are compared to that of the best algorithms known in the literature. Both the new proposals exhibit significant improvements in throughput and delay with respect to the older ones, for various MAN topologies, sizes and buffer dimensions. These results, which in some cases are very close to the theoretical optimum, are achieved with an implementation complexity well within the limits of present day technology. [source] Unstructured grid generation using LiDAR data for urban flood inundation modellingHYDROLOGICAL PROCESSES, Issue 11 2010Ryota Tsubaki Abstract Inundation disasters, caused by sudden water level rise or rapid flow, occur frequently in various parts of the world. Such catastrophes strike not only in thinly populated flood plains or farmland but also in highly populated villages or urban areas. Inundation of the populated areas causes severe damage to the economy, injury, and loss of life; therefore, a proper management scheme for the disaster has to be developed. To predict and manage such adversity, an understanding of the dynamic processes of inundation flow is necessary because risk estimation is performed based on inundation flow information. In this study, we developed a comprehensive method to conduct detailed inundation flow simulations for a populated area with quite complex topographical features using LiDAR (Light Detection and Ranging) data. Detailed geospatial information including the location and shape of each building was extracted from the LiDAR data and used for the grid generation. The developed approach can distinguish buildings from vegetation and treat them differently in the flow model. With this method, a fine unstructured grid can be generated representing the complicated urban land features precisely without exhausting labour for data preparation. The accuracy of the generated grid with different grid spacing and grid type is discussed and the optimal range of grid spacing for direct representation of urban topography is investigated. The developed method is applied to the estimation of inundation flows, which occurred in the basin of the Shin-minato River. A detailed inundation flow structure is represented by the flow model, and the flow characteristics with respect to topographic features are discussed. Copyright © 2010 John Wiley & Sons, Ltd. [source] A study of lightning riskIEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING, Issue 5 2008Takatoshi Shindo Senior Member Abstract It is important to establish a lightning risk management scheme for rational insulation design. In this paper, lightning risk assessment is carried out for a customer facility and a wind turbine blade. The calculated values of lightning risk agree with field experiences. © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source] A novel key management scheme for dynamic multicast communicationsINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 1 2009Chin-Chen Chang Abstract Secure multicasting allows the sender to deliver an identical secret to an arbitrary set of recipients through an insecure broadcasting channel, whereas the unintended recipients cannot obtain the secret. A practical approach for securing multicast communications is to apply a session key to encrypt the transmitted data. However, the challenges of secure multicast are to manage the session keys possessed by a dynamic group of recipients and to reduce the overhead of computation and transmission when the membership is changed. In this paper, we propose a new key management scheme for dynamic multicast communication, which is based on privacy homomorphism and Chinese remainder theorem. Our scheme can efficiently and securely deliver an identical message to multiple recipients. In particular, the complexity of the key update process in our scheme is O(1). Copyright © 2008 John Wiley & Sons, Ltd. [source] A study on a receiver-based management scheme of access link resources for QoS-controllable TCP connectionsINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 7 2006Kazuhiro Azuma Abstract Although the bandwidth of access networks is rapidly increasing with the latest techniques such as DSL and FTTH, the access link bandwidth remains a bottleneck, especially when users activate multiple network applications simultaneously. Furthermore, since the throughput of a standard TCP connection is dependent on various network parameters, including round-trip time and packet loss ratio, the access link bandwidth is not shared among the network applications according to the user's demands. In this thesis, we present a new management scheme of access link resources for effective utilization of the access link bandwidth and control of the TCP connection's throughput. Our proposed scheme adjusts the total amount of the receive socket buffer assigned to TCP connections to avoid congestion at the access network, and assigns it to each TCP connection according to characteristics in consideration of QoS. The control objectives of our scheme are (1) to protect short-lived TCP connections from the bandwidth occupation by long-lived TCP connections, and (2) to differentiate the throughput of the long-lived TCP connections according to the upper-layer application's demands. One of the results obtained from the simulation experiments is that our proposed scheme can reduce the delay of short-lived document transfer perceived by the receiver host by up to about 90%, while a high utilization of access link bandwidth is maintained. Copyright © 2006 John Wiley & Sons, Ltd. [source] A proactive management algorithm for self-healing mobile ad hoc networksINTERNATIONAL JOURNAL OF NETWORK MANAGEMENT, Issue 3 2008Adel F. Iskander The ability to proactively manage mobile ad hoc networks (MANETs) is critical for supporting complex services such as quality of service, security and access control in these networks. This paper focuses on the problem of managing highly dynamic and resource-constrained MANET environments through the proposal of a novel proactive management algorithm (PMA) for self-healing MANETs. PMA is based on an effective integration of autonomous, predictive and adaptive distributed management strategies. Proactive management is achieved through the distributed analysis of the current performance of the mobile nodes utilizing an optimistic discrete event simulation method, which is used to predict the mobile nodes' future status, and execution a proactive fault-tolerant management scheme. PMA takes advantage of distributed parallel processing, flexibility and intelligence of active packets to minimize the management overhead, while adapting to the highly dynamic and resource-constrained nature of MANETs. The performance of the proposed architecture is validated through analytical performance analysis and comparative simulation with the Active Virtual Network Management Protocol. The simulation results demonstrate that PMA not only significantly reduces management control overhead, but also improves both the performance and the stability of MANETs. Copyright © 2007 John Wiley & Sons, Ltd. [source] A dynamic key management solution to access hierarchyINTERNATIONAL JOURNAL OF NETWORK MANAGEMENT, Issue 6 2007Xukai Zou Hierarchical access control (HAC) has been a fundamental problem in computer and network systems. Since Akl and Taylor proposed the first HAC scheme based on number theory in 1983, cryptographic key management techniques for HAC have appeared as a new and promising class of solutions to the HAC problem. Many cryptographic HAC schemes have been proposed in the past two decades. One common feature associated with these schemes is that they basically limited dynamic operations at the node level. In this paper, by introducing the innovative concept of ,access polynomial' and representing a key value as the sum of two polynomials in a finite field, we propose a new key management scheme for dynamic access hierarchy. The newly proposed scheme supports full dynamics at both the node level and user level in a uniform yet efficient manner. Furthermore, the new scheme allows access hierarchy to be a random structure and can be flexibly adapted to many other access models such as ,transfer down' and ,depth-limited transfer'. Copyright © 2007 John Wiley & Sons, Ltd. [source] A heterogeneous-network aided public-key management scheme for mobile ad hoc networksINTERNATIONAL JOURNAL OF NETWORK MANAGEMENT, Issue 1 2007Yuh-Min Tseng A mobile ad hoc network does not require fixed infrastructure to construct connections among nodes. Due to the particular characteristics of mobile ad hoc networks, most existing secure protocols in wired networks do not meet the security requirements for mobile ad hoc networks. Most secure protocols in mobile ad hoc networks, such as secure routing, key agreement and secure group communication protocols, assume that all nodes must have pre-shared a secret, or pre-obtained public-key certificates before joining the network. However, this assumption has a practical weakness for some emergency applications, because some nodes without pre-obtained certificates will be unable to join the network. In this paper, a heterogeneous-network aided public-key management scheme for mobile ad hoc networks is proposed to remedy this weakness. Several heterogeneous networks (such as satellite, unmanned aerial vehicle, or cellular networks) provide wider service areas and ubiquitous connectivity. We adopt these wide-covered heterogeneous networks to design a secure certificate distribution scheme that allows a mobile node without a pre-obtained certificate to instantly get a certificate using the communication channel constructed by these wide-covered heterogeneous networks. Therefore, this scheme enhances the security infrastructure of public key management for mobile ad hoc networks. Copyright © 2006 John Wiley & Sons, Ltd. [source] Reducing signaling traffic in wireless ATM networks through handoff scheme improvementINTERNATIONAL JOURNAL OF NETWORK MANAGEMENT, Issue 5 2002Professor Anna Ha We propose a new handoff call management scheme which reduces signaling traffic in wireless ATM networks and improves the efficiency of the virtual channel. Chaining followed by a make-break algorithm is a suitable handoff scheme for various situations. In the chaining part of the scheme, a chain routing algorithm is studied and compared with the hop-limiting scheme. When the algorithm is implemented in our scheme, it improves the performance of the existing scheme in call drop rates so as to reduce the signaling traffic in wireless ATM networks. Copyright © 2002 John Wiley & Sons, Ltd. [source] Service differentiation using a multi-level RED mechanismINTERNATIONAL JOURNAL OF NETWORK MANAGEMENT, Issue 2 2002Dr. James Aweya This paper describes a multi-level active queue management scheme that combines packet classification and random early detection (RED) capabilities to provide differentiated performance characteristics for different classes of service. The proposed RED scheme uses a simple control-theoretic algorithm to randomly discard packets with a load-dependent probability when a buffer in a router gets congested. Copyright © 2002 John Wiley & Sons, Ltd. [source] Development of mobile broadband interactive satellite access system for Ku/Ka bandINTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 2 2006Yun-Jeong Song Abstract It is difficult to implement the broadband satellite Internet and broadcasting service for mobile environment. The paper presents the design and implementation of a mobile broadband satellite access system. In case of the system design, mobile terminal service is considered a critical factor than fixed terminal services, such as resource management, antenna tracking, weak signal recovery. In the paper, mobile broadband interactive satellite access technology system (MoBISAT) is presented. The system network, which is composed of a star network, consists of time division multiplexing-based forward link and multi-frequency time division multiple access-based return link. The MoBISAT provides both Ku-band satellite TV and Ka-band high-speed Internet base on DVB-S/DVB-RCS standards to the passengers and crews for land, maritime and air vehicles. The key factors of hub and mobile terminal are addressed for the design and implementation of the MoBISAT. Especially, the design and implementation of the return link demodulation method, resource management scheme and mobile terminal structure including mobile antenna are described. Copyright © 2006 John Wiley & Sons, Ltd. [source] Pattern and sustainability of the bushmeat trade in the Haut Niger National Park, Republic of GuineaAFRICAN JOURNAL OF ECOLOGY, Issue 4 2009David Brugiere Abstract To document the bushmeat trade in the buffer zone of the Haut Niger National Park (HNNP), Republic of Guinea, we monitored the number of carcasses offered for sale in 16 villages over a one year period in 2001. Overall, we counted a total of 9134 carcasses from 27 species. This represents a biomass harvest of about 170,000 kg, a figure that could reach 335,100 kg when game consumed by hunters (i.e. not sold) and markets not sampled are taken into account. Ungulates (eleven species) and rodents (four species) accounted for 53.5% and 24.8% of the carcasses counted respectively (80.8% and 11.4% of the total biomass, respectively). The number of carcasses counted in villages bordering a heavily trafficked road was significantly higher than in more rural villages, thus highlighting the stimulating effect of roads on the bushmeat trade. Compared with existing data collected in 1995, the proportion of ungulates counted in the Mansira Moribaya village in 2001 increased significantly while that of rodents decreased significantly. The harvest of duiker species at Mansira Moribaya was in excess of the maximum sustainable harvest. These results of this study were used to establish a sustainable wildlife management scheme in the HNNP. Résumé Pour documenter le commerce de viande de brousse dans la zone tampon du Parc National du Haut Niger, en République de Guinée, nous avons contrôlé le nombre de carcasses proposées à la vente pendant une année (2001) dans 16 villages. En tout, nous avons compté 9 134 carcasses appartenant à 27 espèces. Cela représente un prélèvement de biomasse d'environ 170.000 kg, un chiffre qui pourrait même atteindre 335.100 kg si l'on tient compte de la viande consommée par les chasseurs (c.-à-d. pas vendue) et des marchés qui n'ont pas été repris dans notre échantillon. Les ongulés (11 espèces) et les rongeurs (quatre espèces) représentaient 53,5% et 24,8% des carcasses comptées et comptaient respectivement pour 80,8% et 11,4% de la biomasse totale. Le nombre de carcasses comptées dans les villages longeant une route très fréquentée était significativement plus élevé que dans des villages plus ruraux, ce qui met en évidence l'effet dynamisant des routes sur le commerce de viande de brousse. Comparée aux données existantes récoltées en 1995, la proportion d'ongulés comptés dans le village de Mansira Moribaya en 2001 a augmenté significativement alors que celui des rongeurs a diminué significativement. Le prélèvement des espèces de céphalophes à Mansira Moribaya dépassait le prélèvement maximum soutenable. Les résultats de cette étude ont servi àétablir un programme de gestion durable de la faune sauvage dans le Parc National du Haut Niger. [source] The Use of Extant Non-Indigenous Tortoises as a Restoration Tool to Replace Extinct Ecosystem EngineersRESTORATION ECOLOGY, Issue 1 2010Christine J. Griffiths We argue that the introduction of non-native extant tortoises as ecological replacements for extinct giant tortoises is a realistic restoration management scheme, which is easy to implement. We discuss how the recent extinctions of endemic giant Cylindraspis tortoises on the Mascarene Islands have left a legacy of ecosystem dysfunction threatening the remnants of native biota, focusing on the island of Mauritius because this is where most has been inferred about plant,tortoise interactions. There is a pressing need to restore and preserve several Mauritian habitats and plant communities that suffer from ecosystem dysfunction. We discuss ongoing restoration efforts on the Mauritian offshore Round Island, which provide a case study highlighting how tortoise substitutes are being used in an experimental and hypothesis-driven conservation and restoration project. The immediate conservation concern was to prevent the extinction and further degradation of Round Island's threatened flora and fauna. In the long term, the introduction of tortoises to Round Island will lead to valuable management and restoration insights for subsequent larger-scale mainland restoration projects. This case study further highlights the feasibility, versatility and low-risk nature of using tortoises in restoration programs, with particular reference to their introduction to island ecosystems. Overall, the use of extant tortoises as replacements for extinct ones is a good example of how conservation and restoration biology concepts applied at a smaller scale can be microcosms for more grandiose schemes and addresses more immediate conservation priorities than large-scale ecosystem rewilding projects. [source] Clearing the cervical spine in unconscious polytrauma victims, balancing risks and effective screeningANAESTHESIA, Issue 5 2004C. G. T. Morris Summary Cervical spine injury occurs in 5,10% of cases of blunt polytrauma. A missed or delayed diagnosis of cervical spine injury may be associated with permanent neurological sequelae. However, there is no consensus about the ideal evaluation and management of the potentially injured cervical spine and, despite the publication of numerous clinical guidelines, this issue remains controversial. In addition, many studies are limited in their application to the obtunded or unconscious trauma victim. This review will provide the clinician managing unconscious trauma victims with an assessment of the actual performance of clinical examination and imaging modalities in detecting cervical spine and isolated ligamentous injury, a review of existing guidelines in light of the available evidence, relative risk estimates and a proposed management scheme. [source] Mass flowering crops enhance pollinator densities at a landscape scaleECOLOGY LETTERS, Issue 11 2003Catrin Westphal Abstract To counteract the decline of pollinators in Europe, conservation strategies traditionally focus on enhancing the local availability of semi-natural habitats, as supported by the European Union's Common Agriculture Policy. In contrast, we show that densities of bumblebees, an important pollinator group in agroecosystems, were not determined by the proportion of semi-natural habitats in agricultural landscapes. Instead, bumblebee densities were positively related to the availability of highly rewarding mass flowering crops (i.e. oilseed rape) in the landscape. In addition, mass flowering crops were only effective determinants of bumblebee densities when grown extensively at the landscape scale, but not at smaller local scales. Therefore, future conservation measures should consider the importance of mass flowering crops and the need for management schemes at landscape level to sustain vital pollination services in agroecosystems. [source] Comparison of air quality management strategies of PM10, SO2, and NOx by an industrial source complex model in BeijingENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 1 2007Gaoxiang Ying Abstract The primary air pollutants in the Beijing urban area are fine particulate matter (PM10), sulfur dioxide (SO2), and nitrogen oxides (NOx). Using suitable emission factors for point, area, and line sources from 20 categories of industrial, commercial, domestic and traffic, total yearly mean emissions were estimated at 103.3 kton of PM10, 209.9 kton of SO2, and 225.4 kton of NOx in 1999. To abate this elevated air pollution, three air quality management schemes are adopted. After the implementation, the annual mean ground-level concentrations of air pollutants are predicted by an industrial source complex short term (ISCST3) dispersion model and compared by the geographic information system (GIS). The ISCST3 dispersion model is used by inputting emission inventory and meteorological data with 1 h temporal and 1 km × 1 km spatial resolution. The model validity is verified by its agreement with monitoring data from Beijing's Environmental Protection Bureau. Results indicate that the levels of PM10, SO2, and NOx in Beijing are improved gradually because of the adoption of these three control schemes. The predicted annual mean concentrations decreased from 90.63 to 67.28 ,g/m3 for PM10, 57.94 to 31.77 ,g/m3 for SO2, and 119.97 to 73.83 ,g/m3 for NOx, respectively. © 2007 American Institute of Chemical Engineers Environ Prog 26:33,42, 2007. [source] A life cycle assessment of mechanical and feedstock recycling options for management of plastic packaging wastesENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 2 2005Floriana Perugini Abstract Life cycle assessment (LCA) methodology is generally considered one of the best environmental management tools that can be used to compare alternative eco-performances of recycling or disposal systems. It considers the environment as a whole, including indirect releases, energy and material consumption, emissions in the environment, and waste disposal and follows each activity from the extraction of raw materials to the return of wastes to the ground (cradle-to-grave approach). The study refers to the whole Italian system for recycling of household plastic packaging wastes. The aim was to quantify the overall environmental performances of mechanical recycling of plastic containers in Italy and to compare them with those of conventional options of landfilling or incineration and of a couple of innovative processes of feedstock recycling, low-temperature fluidized bed pyrolysis, and high-pressure hydrogenation. The results confirm that recycling scenarios are always preferable to those of nonrecycling. They also highlight the good environmental performance of new plastic waste management schemes that couple feedstock and mechanical recycling processes. © 2005 American Institute of Chemical Engineers Environ Prog, 2005 [source] The carrying capacity of ecosystemsGLOBAL ECOLOGY, Issue 6 2004Pablo Del Monte-Luna ABSTRACT We analyse the concept of carrying capacity (CC), from populations to the biosphere, and offer a definition suitable for any level. For communities and ecosystems, the CC evokes density-dependence assumptions analogous to those of population dynamics. At the biosphere level, human CC is uncertain and dynamic, leading to apprehensive rather than practical conclusions. The term CC is widely used among ecological disciplines but remains vague and elusive. We propose the following definition: the CC is ,the limit of growth or development of each and all hierarchical levels of biological integration, beginning with the population, and shaped by processes and interdependent relationships between finite resources and the consumers of those resources'. The restrictions of the concept relate to the hierarchical approach. Emergent properties arise at each level, and environmental heterogeneity restrains the measurement and application of the CC. Because the CC entails a myriad of interrelated, ever-changing biotic and abiotic factors, it must not be assumed constant, if we are to derive more effective and realistic management schemes. At the ecosystem level, stability and resilience are dynamic components of the CC. Historical processes that help shape global biodiversity (e.g. continental drift, glaciations) are likely drivers of large-scale changes in the earth's CC. Finally, world population growth and consumption of resources by humanity will necessitate modifications to the paradigm of sustainable development, and demand a clear and fundamental understanding of how CC operates across all biological levels. [source] Seedling recruitment dynamics of forage and weed species under continuous and rotational sheep grazing in a temperate New Zealand pastureGRASS & FORAGE SCIENCE, Issue 2 2005G. R. Edwards Abstract Understanding the grazing conditions under which plant populations are limited by seed availability (seed limitation) is important for devising management schemes that aim to manipulate the establishment of weed and forage species. Seeds of three weed species (Cirsium arvense, C. vulgare and Rumex obtusifolius) and five forage species (Lolium perenne, Lotus uliginosus syn. L. pedunculatus, Paspalum dilatatum, Plantago lanceolata and Trifolium repens) were broadcast sown into L. perenne,T. repens pastures in Manawatu, New Zealand and five sheep-grazing and two slug-grazing (with and without molluscicide) treatments were imposed in a split-plot design. Of the five sheep-grazing treatments, four compared continuous grazing with rotational grazing at intervals of 12, 24 and 36 d in spring, with all four grazed under a common rotation for the remainder of the year. The fifth treatment was continuous grazing all year. Seed sowing increased seedling emergence of C. vulgare, L. perenne, P. lanceolata, R. obtusifolius and T. repens under all sheep- and slug-grazing treatments, with differences in seedling densities persisting for at least 21 months. Seed sowing did not increase seedling densities of C. arvense, L. uliginosus or P. dilatatum. The effects of sheep-grazing management on seedling emergence and survival were uncoupled. For the five seed-limited species, seedling emergence was greater on pastures that were rotationally grazed during spring compared with those that were continuously grazed. However, seedling survival was lower in pastures grazed rotationally during summer, autumn and winter, so that after 21 months seedling numbers were greater on plots that were continuously grazed all year. Exclusion of slugs increased seedling recruitment of T. repens but had no impact on the other species. As weed and forage species responded in a similar way to sheep-grazing management (increased under continuous, decreased under rotational), it is unlikely that the goals of reducing weed invasions and enhancing forage species establishment could be carried out concurrently in established pastures with the same management. [source] An overview of the field and modelling studies on the effects of forest devastation on flooding and environmental issuesHYDROLOGICAL PROCESSES, Issue 5 2010Yuichi Onda Abstract Intensive field observations as well as monitoring of discharge, water quality, and soil erosion have been conducted in forest plantations in order to identify the effects of forest cover and management practices on runoff generation, sediment transport, and downstream environmental issues. Five experimental catchments, each with rather uniform lithology, were established in both managed and unmanaged plantations of Japanese cypress and cedar, as well as broadleaf forests. Field monitoring was conducted from sub-plots (e.g. splash cups) to small hillslope plots (0·5 × 2 m) to large hillslope-scale plots to first order streams (0·1,4 ha) and finally to larger catchments (>4 ha) in a nested structure. Remote sensing techniques were employed to identify broad scale forest stand and soil surface conditions. As part of this integrated study, these field-based monitoring and remote sensing techniques provide information for modelling runoff generation and developing adaptive management schemes with respect to catchment-scale water resources. Copyright © 2010 John Wiley & Sons, Ltd. [source] Analytical approach to the optimal adaptation rate of reconfigurable radio networksINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 7 2008R. Fraile Abstract Flexible radio resource management schemes are nowadays used within a wide range of systems. However, the optimal selection for their adaptation rate is still an open research issue. This paper presents an analytical approach to such problem, which consists in a combined analysis of the dynamics of the session-arrival process and the estimation of the mean traffic load from network measurements. From this study, it is concluded that both aspects pose an upper limit on the optimal system adaptation rate, being the most restrictive the one depending on the mean traffic load estimation. A specific procedure for deriving such limit on adaptation rate is provided. It is shown that the derived value directly depends on the mean service duration. The application of the whole analysis is illustrated with an example based on a set of measurements from a live network. Copyright © 2008 John Wiley & Sons, Ltd. [source] Town centre management schemes in the UK: marketing and performance indicatorsINTERNATIONAL JOURNAL OF NONPROFIT & VOLUNTARY SECTOR MARKETING, Issue 4 2004Sophie Hogg While town centre management (TCM) has proved to be a successful strategy to maintain, improve and regenerate town centres through local partnership, there has been relatively little attention drawn to the marketing of TCM schemes. This paper explores the issues surrounding the use of key performance indicators (KPIs) for the marketing of TCM schemes in the context of wider place marketing activities undertaken by towns and cities. Drawing on evidence from a questionnaire survey of town centre managers, it is posited that they might usefully employ carefully selected KPI data to maintain and attract private investment to TCM schemes from internal and external town centre stakeholders. The paper then introduces a typology for the use of KPI marketing in town centre management. Copyright © 2004 Henry Stewart Publications [source] Simulation analyses of weighted fair bandwidth-on-demand (WFBoD) process for broadband multimedia geostationary satellite systemsINTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 4 2005Güray Açar Abstract Advanced resource management schemes are required for broadband multimedia satellite networks to provide efficient and fair resource allocation while delivering guaranteed quality of service (QoS) to a potentially very large number of users. Such resource management schemes must provide well-defined service segregation to the different traffic flows of the satellite network, and they must be integrated with some connection admission control (CAC) process at least for the flows requiring QoS guarantees. Weighted fair bandwidth-on-demand (WFBoD) is a resource management process for broadband multimedia geostationary (GEO) satellite systems that provides fair and efficient resource allocation coupled with a well-defined MAC-level QoS framework (compatible with ATM and IP QoS frameworks) and a multi-level service segregation to a large number of users with diverse characteristics. WFBoD is also integrated with the CAC process. In this paper, we analyse via extensive simulations the WFBoD process in a bent-pipe satellite network. Our results show that WFBoD can be used to provide guaranteed QoS for both non-real-time and real-time variable bit rate (VBR) flows. Our results also show how to choose the main parameters of the WFBoD process depending on the system parameters and on the traffic characteristics of the flows. Copyright © 2005 John Wiley & Sons, Ltd. [source] Alpha and beta diversity of arthropods and plants in organically and conventionally managed wheat fieldsJOURNAL OF APPLIED ECOLOGY, Issue 4 2007YANN CLOUGH Summary 1Most studies in applied ecology use measures of ,-diversity measures, i.e. the mean diversity on a site, to compare biodiversity effects of different management schemes. The total or ,-diversity within a region, however, need not be correlated with the mean ,-diversity within any site of the region. Thus, analyses of ,-diversity alone may misrepresent the contributions of other diversity components (,) to total diversity (,). 2We apply a biodiversity-partitioning approach to species richness from a comparison between paired organic and conventional wheat fields in 21 sites from three regions in Germany, where we recorded plants, bees, carabids, staphylinids and spiders in the centre and edge of the fields. 3Relative values of ,- and ,-diversity depended on taxon. Both between-site and between-region ,-diversity were very high (in total 60,85%). ,-Diversity and between-site ,-diversity was larger on the edge than in the centre of fields for all taxa. 4,-Diversity, between-site ,-diversity of plants and bees and between-region ,-diversity of bees were higher in organic than in conventional fields, providing local as well as larger-scale species richness benefits. ,-Diversity did not differ between management types for the epigaeic arthropods. Lower between-site ,-diversity was found for spiders in organic fields than in conventional fields, resulting in higher total species richness in conventionally managed wheat. 5Similarity in composition of landscapes surrounding the study fields was correlated with similarity in species composition for epigaeic arthropods in conventional fields. For this group of organisms the variability of landscapes in the sample contributed to increasing ,-diversity. 6Synthesis and applications.,-Diversity accounts for the major part of species richness in agro-ecosystems. Implementing an agri-environment scheme such as organic agriculture may result in either an additional increase of total diversity, as could be shown for plants and bees, or in a decrease in total diversity as was the case for the spiders. Therefore, ,-diversity needs to be included in the evaluation of different management schemes for conservation. For plant and bees it is recommended to implement agri-environment schemes in contrasting landscapes and in different regions to maximize total species richness benefits. [source] Can management compensate for atmospheric nutrient deposition in heathland ecosystems?JOURNAL OF APPLIED ECOLOGY, Issue 4 2006WERNER HÄRDTLE Summary 1Atmospheric nutrient deposition has contributed to widespread changes in heathlands throughout Europe. As a consequence, management is now being considered as a potential tool with which to compensate for increased nutrient loads. Currently, only limited information is available on the extent to which management measures could compensate for atmospheric nutrient deposition. We hypothesized that low-intensity management measures are not sufficient to counterbalance current nutrient inputs, particularly of nitrogen (N). 2In order to improve heathland management schemes, we evaluated the effectiveness of different management measures in reducing the impact of ongoing atmospheric nutrient loads. We compared the effects of mowing, prescribed burning (low-intensity management) and sod-cutting (high-intensity management) on heathland nutrient budgets [N, calcium (Ca), potassium (K), magnesium (Mg) and phosphorus (P)] in the Lueneburg Heath nature reserve (north-west Germany). Nutrient balances were calculated by analysing the present-day input, the output as a result of the removal of biomass/humus horizons, and changes in leaching rates. 3Nutrient losses by increased leaching following management measures were negligible compared with nutrient losses caused by the removal of above-ground biomass or humus horizons. The total quantities of nutrients removed by sod-cutting were equivalent to between 37 and 176 years of atmospheric input (for N, 89 years). 4In contrast, the quantities of N removed by mowing and prescribed burning were equivalent to only 5 years of atmospheric input. Thus, heathlands subjected to such treatments will accumulate N in the long term. In addition, output,input ratios for phosphorus (P) exceeded those for N in the mowing and sod-cutting experiments. It is therefore likely that heathlands currently (co-) limited by N will shift to being more P-limited in the long term. This will promote species that are well adapted to P-limited sites (e.g. Molinia caerulea). 5Synthesis and applications. This study shows that low-intensity management cannot compensate for atmospheric N loads in the long term. Consequently, high-intensity management measures are an indispensable tool in preserving a long-term balanced N budget in heathlands. In order to maintain a diverse structure, managers need to combine low- and high-intensity management measures. Prescribed burning proved to be the best means of avoiding an increasing P shortage, because this measure causes very low P outputs. [source] Ecological relevance of temporal stability in regional fish catchesJOURNAL OF FISH BIOLOGY, Issue 5 2003H. Hinz The concept of habitat selection based on ,Ideal Free Distribution' theory suggests that areas of high suitability may attract larger quantities of fishes than less suitable or unsuitable areas. Catch data were used from groundfish surveys to identify areas of consistently high densities of whiting Merlangius merlangus, cod Gadus morhua and haddock Melanogrammus aeglefinus in the Irish Sea and plaice Pleuronectes platessa, sole Solea solea, lemon sole Microstomus kitt in the English Channel over a period of 10 and 9 years respectively. A method was introduced to delineate areas of the seabed that held consistently high numbers of fishes objectively from large datasets. These areas may constitute important habitat characteristics which may merit further scientific investigations in respect to ,Essential Fish Habitats'(EFH). In addition, the number of stations with consistently high abundances of fishes and the number of stations where no fishes were caught gave an indication of the site specificity of the fish species analysed. For the gadoids, whiting was found to be less site specific than cod and haddock, while for the flatfishes, plaice and sole were less site specific than lemon sole. The findings are discussed in the context of previously published studies on dietary specializm. The site specificity of demersal fishes has implications for the siting process for marine protected areas as fish species with a strong habitat affinity can be expected to benefit more from such management schemes. [source] | ||||||||||||||||