Condensed state spaces for symmetrical Coloured Petri Nets

This paper deals with state spaces. A state space is a directed graph with a node for each reachable state and an arc for each possible state change. We describe how symmetries of the modelled system can be exploited to obtain much more succinct state space analysis. The symmetries induce equivalence classes of states and equivalence classes of state changes. It is then possible to construct a condensed state space where each node represents an equivalence class of states while each arc represents an equivalence class of state changes. Such a condensed state space is often much smaller than the full state space and it is also much faster to construct. Nevertheless, it is possible to use the condensed state space to verify the same kind of behavioural properties as the full state space. hence, we do not lose analytic power.We define state spaces and condensed state spaces for a language called Coloured Petri Nets (CP-nets). This language is in widespread use for the modelling and analysis of concurrent systems. However, our techniques are general and they can be used for many other kinds of labelled transition systems. The paper does not assume that the reader is familiar with CP-nets (or Petri nets in general)—although such knowledge will, of course, be a help. The first four sections of the paper introduce the basic concepts of CP-nets. The next three sections deal with state spaces, condensed state spaces and computer tools for state space analysis. Finally, there is a short conclusion.     

Restricted overlapping balancing domain decomposition methods and restricted coarse problems for the Helmholtz problem

Overlapping balancing domain decomposition methods and their combination with restricted additive Schwarz methods are proposed for the Helmholtz equation. These new methods also extend previous work on non-overlapping balancing domain decomposition methods toward simplifying their coarse problems and local solvers. They also extend restricted Schwarz methods, originally designed to overlapping domain decomposition and Dirichlet local solvers, to the case of non-overlapping domain decomposition and/or Neumann and Sommerfeld local solvers. Finally, we introduce coarse spaces based on partitions of unity and planes waves, and show how oblique projection coarse problems can be designed from restricted additive Schwarz methods. Numerical tests are presented.     

Daily impact of climate on the pattern of urban family life : Indigenous courtyard houses of Baghdad regions of the hot-dry climates Part I: Daily shifts or daily movements in summer

During the day, there are considerable variations in the climatic factors prevailing in these regions. This is especially so during the 24-hour daily cycle of the long, hot and dry summer (mid-May to midOctober). Such climatic conditions have had a considerable impact on the daily living pattern of family life in the same season, particularly in the urban areas. During the same 24-hour cycle, they have compelled the inhabitants to shift their living activities both vertically in section and horizontally in plan; they do this in pursuit of more acceptable, if not, desirable internal thermal environmental ambience.     

Optimal control and geodesic flows

In this paper we analyze and generalize, from the point of view of the maximum principle, a class of nonlinear optimal control problems originally introduced in Brockett (1994). The optimal control problems discussed here lie on the adjoint orbits of compact Lie groups or on Grassmann manifolds and the structure of the equations that arise depends on the metric used - the so-called normal metric. We consider some special cases of the general problem and their meaning from the point of view of Riemannian geometry and Hamiltonian mechanics.     

Organisational spaces and intelligent machines: A metaphorical approach to ethics

This paper tackles the main changes that have taken place in the mechanical worldview of simple, self-regulating and intelligent machines, and studies their repercussions at the ethical and organisational level. These views of machines agree with the scientific, human-relations and postmodern proposals in organisation theory, in that they are in fact reflections on human nature which depend on metaphorical devices within which the machine metaphor is central.If we were only to govern our actions by the reflection of the inert world's irrevocable laws in our own consciousness, we would be completely unmoral, or to put it better, amoral; Good and Bad would lack meaning for us... A. Caso A System is an imaginary machine... A. Smith     

推广的Kantorovi多项式的L_p保持Lipschitz条件性

本文研究推广的Kantorovi多项式P_n~*(f, x)在L_p[0,1]空间中的保持Lipschitz条件性质。     

ReSpecT Nets: Towards an Analysis Methodology for ReSpecT Specifications

A key feature for infrastructures providing coordination services is the ability to define the behaviour of coordination abstractions according to the requirements identified at design-time. We take as a representative for this scenario the logic-based language ReSpecT (Reaction Specification Tuples), used to program the reactive behaviour of tuple centres. ReSpecT specifications are at the core of the engineering methodology underlying the TuCSoN infrastructure, and are therefore the “conceptual place” where formal methods can be fruitfully applied to guarantee relevant system properties.In this paper we introduce ReSpecT nets, a formalism that can be used to describe reactive behaviours that can succeed and fail, and that allows for an encoding to Petri nets with inhibitor arcs. ReSpecT nets are introduced to give a core model to a fragment of the ReSpecT language, and to pave the way for devising an analysis methodology including formal verification of safety and liveness properties. In particular, we provide a semantics to ReSpecT specifications through a mapping to ReSpecT nets. The potential of this approach for the analysis of ReSpecT specifications is discussed, presenting initial results for the analysis of safety properties.     

Approximation of Löwdin orthogonalization to a spectrally efficient orthogonal overlapping PPM design for UWB impulse radio

In this paper we consider the design of spectrally efficient time-limited pulses for ultra-wideband (UWB) systems using an overlapping pulse position modulation scheme. For this we investigate an orthogonalization method, which was developed in 1950 by Löwdin [1] and [2]. Our objective is to obtain a set of N orthogonal (Löwdin) pulses, which remain time-limited and spectrally efficient for UWB systems, from a set of N equidistant translates of a time-limited optimal spectral designed UWB pulse. We derive an approximate Löwdin orthogonalization (ALO) by using circulant approximations for the Gram matrix to obtain a practical filter implementation as a tapped-delay-line [7]. We show that the centered ALO and Löwdin pulses converge pointwise to the same square-root Nyquist pulse as N tends to infinity. The set of translates of the square-root Nyquist pulse forms an orthonormal basis for the shift-invariant-space generated by the initial spectral optimal pulse. The ALO transformation provides a closed-form approximation of the Löwdin transformation, which can be implemented in an analog fashion without the need of analog to digital conversions. Furthermore, we investigate the interplay between the optimization and the orthogonalization procedure by using methods from the theory of shift-invariant-spaces. Finally we relate our results to wavelet and frame theory.     

多层次构成的新加坡公共空间

新加坡城市的历史不到200年,自1972年以来,这座城市经历了由不同优先级和城市议程造成的重大变革。现状的城市结构可以解析为不同的城市图层,由政府谨慎地规划设计和管理整个城市的公共空间由不同的图层交叠构成,对这些公共空间的图层进行总结并分析其动因,力求提供一个理解新加坡城市结构的独特视角。     

Variation and Distribution: Forest Patterns as a Model for Urban Morphologies

What can we learn from the spatial logic of collections of trees in the rainforest? Evan Greenberg of the EmTech programme at the Architectural Association (AA) School of Architecture in London and George Jeronimidis of the Centre for Biomimetics at the University of Reading combine forces to analyse the rainforest's morphology and its potential as an urban model. They suggest how the sectional height differentiation of trees could present a new way of thinking about urban organisation, accommodating varied microclimates, programmes and the city's infrastructural flows.