Can(Plan)+: Extending the Operational Semantics of the BDI Architecture to deal with Uncertain Information

The BDI architecture, where agents are modelled based on their beliefs, desires and intentions, provides a practical approach to develop large scale systems. However, it is not well suited to model complex Supervisory Control And Data Acquisition (SCADA) systems pervaded by uncertainty. In this paper we address this issue by extending the operational semantics of Can(Plan) into Can(Plan)+. We start by modelling the beliefs of an agent as a set of epistemic states where each state, possibly using a different representation, models part of the agent's beliefs. These epistemic states are stratified to make them commensurable and to reason about the uncertain beliefs of the agent. The syntax and semantics of a BDI agent are extended accordingly and we identify fragments with computationally efficient semantics. Finally, we examine how primitive actions are affected by uncertainty and we define an appropriate form of lookahead planning.

Very high speed 17 Gbps SHACAL encryption architecture

Very high speed and low area hardware architectures of the SHACAL-1 encryption algorithm are presented in this paper. The SHACAL algorithm was a submission to the New European Schemes for Signatures, Integrity and Encryption (NESSIE) project and it is based on the SHA-1 hash algorithm. To date, there have been no performance metrics published on hardware implementations of this algorithm. A fully pipelined SHACAL-1 encryption architecture is described in this paper and when implemented on a Virtex-II X2V4000 FPGA device, it runs at a throughput of 17 Gbps. A fully pipelined decryption architecture achieves a speed of 13 Gbps when implemented on the same device. In addition, iterative architectures of the algorithm are presented. The SHACAL-1 decryption algorithm is derived and also presented in this paper, since it was not provided in the submission to NESSIE. © Springer-Verlag Berlin Heidelberg 2003.

OpenFlow Multi-Table Lookup Architecture for Multi-Gigabit Software Defined Networking (SDN)

The proposed multi-table lookup architecture provides SDN-based, high-performance packet classification in an OpenFlow v1.1+ SDN switch. The objective of the demonstration is to show the functionality of the architecture deployed on the NetFPGA SUME Platform.

Network Connectivity Proxy: Architecture, Implementation, and Performance Analysis

Several studies in the last decade have pointed out that many devices, such as computers, are often left powered on even when idle, just to make them available and reachable on the network, leading to large energy waste. The concept of network connectivity proxy (NCP) has been proposed as an effective means to improve energy efficiency. It impersonates the presence of networked devices that are temporally unavailable, by carrying out background networking routines on their behalf. Hence, idle devices could be put into low-power states and save energy. Several architectural alternatives and the applicability of this concept to different protocols and applications have been investigated. However, there is no clear understanding of the limitations and issues of this approach in current networking scenarios. This paper extends the knowledge about the NCP by defining an extended set of tasks that the NCP can carry out, by introducing a suitable communication interface to control NCP operation, and by designing, implementing, and evaluating a functional prototype.

State architecture: subsidiarity, devolution, federalism and independence

This chapter examines the current ‘architecture’ of the British state, in particular the way in which governmental power is distributed among the nations of the United Kingdom. The theme of this chapter will be to show how the continuing (and, as James Bryce argued, inevitable) tension between centripetal and centrifugal forces can be usefully applied to power relations between the various nations of the United Kingdom, and between these nations and Europe, providing a basis for analyzing how these nations are drawn or impelled by some forces towards a centralized unitary polity, whilst at the same time other forces tend towards dispersion of power. The resulting pattern might be analyzed along a spectrum from centralization to independence, with subsidiarity, devolution and federalism being seen as weigh stations along the way, but given how complex the variations in the distribution of power between these nations and the centre have become over time, the construction of any static architectural blueprint of the British state is bound to be misleading. Indeed, the architectural metaphor, with its implications of stability might usefully be rethought.

Architecture as Pedagogy: Alive and Kicking

This workshop draws on an emerging collaborative body of research by Lovett, Morrow and McClean that aims to understand architecture and its processes as a form of pedagogical practice: a civic pedagogy.

Architectural education can be valued not only as a process that delivers architecture-specific skills and knowledges, but also as a process that transforms people into critically active contributors to society. We are keen to examine how and where those skills are developed in architectural education and trace their existence and/or application within practice. We intend to examine whether some architectural and spatial practices are intrinsically pedagogical in their nature and how the level of involvement of clients, users and communities can mimic the project-based learning of architectural education – in particularly in the context of ‘live project learning’

1. This workshop begins with a brief discussion paper from Morrow that sets out the arguments behind why and how architecture can be understood as pedagogy. It will do so by presenting firstly the relationship between architectural practice and pedagogy, drawing out both contemporary and historical examples of architecture and architects acting pedagogically. It will also consider some other forms of creative practice that explicitly frame themselves pedagogically, and focus on participatory approaches in architectural practice that overlap with inclusive and live pedagogies, concluding with a draft and tentative abstracted pedagogical framework for architectural practice.

2. Lovett will examine practices of architectural operation that have a pedagogical approach, or which recognise within themselves an educational subtext/current. He is most interested in a 'liveness' beyond the 'Architectural Education' of university institutions. The presentation will question the scope for both spatial empowerment / agency and a greater understanding and awareness of the value of good design when operating as architects with participant-clients younger than 18, older than 25 or across varied parts of society. Positing that the learning might be greatest when there are no prescribed 'Learning Outcomes' and that such work might depend on risk-taking and playfulness, the presentation will be a curated showcase drawing on his own ongoing work.

Both brief presentations will inform the basis of the workshop’s discussion which hopes to draw on participants views and expereinces to enrich the research process. The intention is that the overall workshop will lead to a call for contributors and respondents to a forthcoming publication on ‘Architecture as Pedagogy’.

Fast Byzantine Leader Election in Dynamic Networks

We study the fundamental Byzantine leader election problem in dynamic networks where the topology can change from round to round and nodes can also experience heavy {\em churn} (i.e., nodes can join and leave the network continuously over time). We assume the full information model where the Byzantine nodes have complete knowledge about the entire state of the network at every round (including random choices made by all the nodes), have unbounded computational power and can deviate arbitrarily from the protocol. The churn is controlled by an adversary that has complete knowledge and control over which nodes join and leave and at what times and also may rewire the topology in every round and has unlimited computational power, but is oblivious to the random choices made by the algorithm. Our main contribution is an $O(\log^3 n)$ round algorithm that achieves Byzantine leader election under the presence of up to $O({n}^{1/2 - \epsilon})$ Byzantine nodes (for a small constant $\epsilon > 0$) and a churn of up to \\$O(\sqrt{n}/\poly\log(n))$ nodes per round (where $n$ is the stable network size).The algorithm elects a leader with probability at least $1-n^{-\Omega(1)}$ and guarantees that it is an honest node with probability at least $1-n^{-\Omega(1)}$; assuming the algorithm succeeds, the leader's identity will be known to a $1-o(1)$ fraction of the honest nodes. Our algorithm is fully-distributed, lightweight, and is simple to implement. It is also scalable, as it runs in polylogarithmic (in $n$) time and requires nodes to send and receive messages of only polylogarithmic size per round.To the best of our knowledge, our algorithm is the first scalable solution for Byzantine leader election in a dynamic network with a high rate of churn; our protocol can also be used to solve Byzantine agreement in a straightforward way.We also show how to implement an (almost-everywhere) public coin with constant bias in a dynamic network with Byzantine nodes and provide a mechanism for enabling honest nodes to store information reliably in the network, which might be of independent interest.

Investigation of thermal resistance and bridging in examples of contemporary and vernacular solid wall architecture

Contemporary architecture has tended to increase envelope insulation levels in an unceasing effort to reduce U-values. Traditional masonry architecture in contrast was devoid of insulation, except for the inherent insulative nature of vernacular materials. Also the consistency of the outer membrane of the building skin diminished any impact due to bridging. In contemporary highly insulated walls bridges are numerous due to the necessity to bind inner and outer structural skins through insulation layers. This paper examines thermal bridging in an example of contemporary façade design and compares it with an example of traditional vernacular architecture currently being researched which is characterized by a lack of bridging elements. Focus is given to heavy weight materials of high thermal mass, which appropriately for passive architecture help moderate fluctuations in internal temperature. In an extensive experimental study samples of highly insulated precast concrete sandwich panels and lime rendered masonry walls are tested in a guarded hot-box. The building construction methods are compared for static and dynamic thermal transmittance, via heat flux and surface temperature differential measurements. Focus is given to the differential heat loss due to the thermal bridging in the sandwich panels and its associated impact on overall heat loss relative to traditional masonry construction.