116,045 research outputs found

    Research priorities in land use and land-cover change for the Earth System and Integrated Assessment Modelling

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    This special issue has highlighted recent and innovative methods and results that integrate observations and modelling analyses of regional to global aspect of biophysical and biogeochemical interactions of land-cover change with the climate system. Both the Earth System and the Integrated Assessment modeling communities recognize the importance of an accurate representation of land use and land-cover change to understand and quantify the interactions and feedbacks with the climate and socio-economic systems, respectively. To date, cooperation between these communities has been limited. Based on common interests, this work discusses research priorities in representing land use and land-cover change for improved collaboration across modelling, observing and measurement communities. Major research topics in land use and land-cover change are those that help us better understand (1) the interaction of land use and land cover with the climate system (e.g. carbon cycle feedbacks), (2) the provision of goods and ecosystem services by terrestrial (natural and anthropogenic) land-cover types (e.g. food production), (3) land use and management decisions and (4) opportunities and limitations for managing climate change (for both mitigation and adaptation strategies

    An improved multi-agent simulation methodology for modelling and evaluating wireless communication systems resource allocation algorithms

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    Multi-Agent Systems (MAS) constitute a well known approach in modelling dynamical real world systems. Recently, this technology has been applied to Wireless Communication Systems (WCS), where efficient resource allocation is a primary goal, for modelling the physical entities involved, like Base Stations (BS), service providers and network operators. This paper presents a novel approach in applying MAS methodology to WCS resource allocation by modelling more abstract entities involved in WCS operation, and especially the concurrent network procedures (services). Due to the concurrent nature of a WCS, MAS technology presents a suitable modelling solution. Services such as new call admission, handoff, user movement and call termination are independent to one another and may occur at the same time for many different users in the network. Thus, the required network procedures for supporting the above services act autonomously, interact with the network environment (gather information such as interference conditions), take decisions (e.g. call establishment), etc, and can be modelled as agents. Based on this novel simulation approach, the agent cooperation in terms of negotiation and agreement becomes a critical issue. To this end, two negotiation strategies are presented and evaluated in this research effort and among them the distributed negotiation and communication scheme between network agents is presented to be highly efficient in terms of network performance. The multi-agent concept adapted to the concurrent nature of large scale WCS is, also, discussed in this paper

    "The fridge door is open" : temporal verification of a robotic assistant's behaviours

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    Robotic assistants are being designed to help, or work with, humans in a variety of situations from assistance within domestic situations, through medical care, to industrial settings. Whilst robots have been used in industry for some time they are often limited in terms of their range of movement or range of tasks. A new generation of robotic assistants have more freedom to move, and are able to autonomously make decisions and decide between alternatives. For people to adopt such robots they will have to be shown to be both safe and trustworthy. In this paper we focus on formal verification of a set of rules that have been developed to control the Care-O-bot, a robotic assistant located in a typical domestic environment. In particular, we apply model-checking, an automated and exhaustive algorithmic technique, to check whether formal temporal properties are satisfied on all the possible behaviours of the system. We prove a number of properties relating to robot behaviours, their priority and interruptibility, helping to support both safety and trustworthiness of robot behaviours

    Resourceful leadership: how directors of children’s services improve outcomes for children, full report

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    Leading for Outcomes is a unique study into senior leadership in children’s services in England, drawing on in-depth primary research with leaders in eight local authorities, and 22 directors of children’s services. The eight local authorities were selected on a range of factors but primarily to represent existing high performers or rapidly improving authorities in terms of outcomes. The research was commissioned by the National College in partnership with C4EO, and completed by a team comprising Deloitte, Navigate and the University of Oxford. The study was completed during 2010. The key concept the Leading for Outcomes research has uncovered is that of the resourceful leader1. This report sets out a definition of resourcefulness and the eight core behaviours of resourceful leaders. It then discusses resourcefulness within three specific contexts that emerged as part of the research: leading change, leading in a time of shock, and managing the corporate and political landscape

    Priority-based intersection management with kinodynamic constraints

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    We consider the problem of coordinating a collection of robots at an intersection area taking into account dynamical constraints due to actuator limitations. We adopt the coordination space approach, which is standard in multiple robot motion planning. Assuming the priorities between robots are assigned in advance and the existence of a collision-free trajectory respecting those priorities, we propose a provably safe trajectory planner satisfying kinodynamic constraints. The algorithm is shown to run in real time and to return safe (collision-free) trajectories. Simulation results on synthetic data illustrate the benefits of the approach.Comment: to be presented at ECC2014; 6 page

    Dynamic cyber-incident response

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    Permission to make digital or hard copies of this publication for internal use within NATO and for personal or educational use when for non-profi t or non-commercial purposes is granted providing that copies bear this notice and a full citation on the first page. Any other reproduction or transmission requires prior written permission by NATO CCD COE.Traditional cyber-incident response models have not changed significantly since the early days of the Computer Incident Response with even the most recent incident response life cycle model advocated by the US National Institute of Standards and Technology (Cichonski, Millar, Grance, & Scarfone, 2012) bearing a striking resemblance to the models proposed by early leaders in the field e.g. Carnegie-Mellon University (West-Brown, et al., 2003) and the SANS Institute (Northcutt, 2003). Whilst serving the purpose of producing coherent and effective response plans, these models appear to be created from the perspectives of Computer Security professionals with no referenced academic grounding. They attempt to defend against, halt and recover from a cyber-attack as quickly as possible. However, other actors inside an organisation may have priorities which conflict with these traditional approaches and may ultimately better serve the longer-term goals and objectives of an organisation

    Reconfigurable Decorated PT Nets with Inhibitor Arcs and Transition Priorities

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    In this paper we deal with additional control structures for decorated PT Nets. The main contribution are inhibitor arcs and priorities. The first ensure that a marking can inhibit the firing of a transition. Inhibitor arcs force that the transition may only fire when the place is empty. an order of transitions restrict the firing, so that an transition may fire only if it has the highest priority of all enabled transitions. This concept is shown to be compatible with reconfigurable Petri nets

    The integrated use of enterprise and system dynamics modelling techniques in support of business decisions

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    Enterprise modelling techniques support business process re-engineering by capturing existing processes and based on perceived outputs, support the design of future process models capable of meeting enterprise requirements. System dynamics modelling tools on the other hand are used extensively for policy analysis and modelling aspects of dynamics which impact on businesses. In this paper, the use of enterprise and system dynamics modelling techniques has been integrated to facilitate qualitative and quantitative reasoning about the structures and behaviours of processes and resource systems used by a Manufacturing Enterprise during the production of composite bearings. The case study testing reported has led to the specification of a new modelling methodology for analysing and managing dynamics and complexities in production systems. This methodology is based on a systematic transformation process, which synergises the use of a selection of public domain enterprise modelling, causal loop and continuous simulationmodelling techniques. The success of the modelling process defined relies on the creation of useful CIMOSA process models which are then converted to causal loops. The causal loop models are then structured and translated to equivalent dynamic simulation models using the proprietary continuous simulation modelling tool iThink
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