198 research outputs found

    Conceptual models of urban environmental information systems - toward improved information provision

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    Cities are the hub of European society - for over a millennium, they are the locus of social, political and economic development. As the core of intensive and creative human activity, they are also the place where the environmental externalities that accompany rapid development are most visible. The environmental consequences of urban development have been recognised long ago, as in the case of London, where in 1388 legislation was introduced to control pollutant emissions (Lowenthal, 1990). Similar historical environmental regulations can be demonstrated for many cities in Europe. However, while for most of history those who govern the city (be it the sovereign, city elders or local government) where responsible for the control, mitigation and management of the common environment in the city, the last 30 years are a period of profound change. This is due to the trend toward improved participation in environmental decision making . a more inclusive and open approach to decisions that deal with the city commons. This change did not occurre overnight but rather gradually. For example, in the United Kingdom, it was the Town and Country Planning Act of 1947 which introduced public scrutiny to changes in the urban form (Rydin, 1998), or the development of public involvement in environmental impact assessment of urban projects as developed in many countries throughout the developed world during the 1970s and 1980s (Gilpin 1995). These changes accelerate within the last three decades, and especially since the publication of .Our Common Future. (WCED and Brundtland 1987), the acceptance of the .Sustainable Development. principles and the Rio conference. A quiet (mini) revolution happened in Europe not long ago, toward the end of 1998 when the members of the United Nations Economic Commission for Europe (UN/ECE) signed the .Convention on Access to Information, Public Participation in Decision Making and Access to Justice in Environmental Matters. - the Aarhus Convention (UN/ECE 1998). The convention is expected to come into force by the end of 2001, and calls the governments and public authorities to open up access to environmental information as a means to improve public participation in environmental decision making and awareness of environmental issues (UN/ECE, 1998). However, these declarations on the value and importance of environmental information do not match our level of understanding on the role of environmental information in decision making processes, and especially on the role of information in improving awareness and participation. Therefore, it is useful to take a step back, and to try and evaluate how environmental information and access to it and its use support public involvement in such processes. This paper is aimed to offer a framework that can assist us in the analytical process of understanding environmental information use. It focuses on public access and assumes that environmental information will be delivered to the public through the Internet. Such assumption is based on the current trend within public authorities is to use Information and Communication Technology (ICT) as a major delivery medium and it seems that it will become more so in the near future (OECD 2000). The framework which this paper presents, is based on Soft Systems Methodology (SSM) study which unpacked some of the core issues relating to public access and use of environmental information (Haklay, 2001). Although the aim here is not to discuss the merits of SSM, but to focus on the conceptual models, some introduction to the techniques that are used here is needed. Therefore, the following section opens with introduction to SSM and its techniques. The core of the paper is dedicated to the development of conceptual models. After presenting the conceptual models, some conclusions about these models and their applications are drown

    Multi-disciplinary optimization of aeroservoelastic systems

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    New methods were developed for efficient aeroservoelastic analysis and optimization. The main target was to develop a method for investigating large structural variations using a single set of modal coordinates. This task was accomplished by basing the structural modal coordinates on normal modes calculated with a set of fictitious masses loading the locations of anticipated structural changes. The following subject areas are covered: (1) modal coordinates for aeroelastic analysis with large local structural variations; and (2) time simulation of flutter with large stiffness changes

    On the lower bound of the discrepancy of (t; s) sequences: I

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    We find the exact lower bound of the discrepancy of shifted Niedereiter's sequences.Comment: Minor change

    Multi-disciplinary optimization of aeroservoelastic systems

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    Efficient analytical and computational tools for simultaneous optimal design of the structural and control components of aeroservoelastic systems are presented. The optimization objective is to achieve aircraft performance requirements and sufficient flutter and control stability margins with a minimal weight penalty and without violating the design constraints. Analytical sensitivity derivatives facilitate an efficient optimization process which allows a relatively large number of design variables. Standard finite element and unsteady aerodynamic routines are used to construct a modal data base. Minimum State aerodynamic approximations and dynamic residualization methods are used to construct a high accuracy, low order aeroservoelastic model. Sensitivity derivatives of flutter dynamic pressure, control stability margins and control effectiveness with respect to structural and control design variables are presented. The performance requirements are utilized by equality constraints which affect the sensitivity derivatives. A gradient-based optimization algorithm is used to minimize an overall cost function. A realistic numerical example of a composite wing with four controls is used to demonstrate the modeling technique, the optimization process, and their accuracy and efficiency

    On the lower bound of the discrepancy of Halton's sequence

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    Let (Hs(n))n1 (H_s(n))_{n \geq 1} be an ss-dimensional Halton's sequence. Let DND_N be the discrepancy of the sequence (Hs(n))n=1N (H_s(n))_{n = 1}^{N} . It is known that NDN=O(lnsN)ND_N =O(\ln^s N) as NN \to \infty . In this paper we prove that this estimate is exact: \overline{\lim}_{ N \to \infty} N \ln^{-s}(N) D_N >0. $

    A Jewish and (Declining) Democratic State? Constitutional Retrogression in Israel

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    This Article describes and analyzes an increasing trend of contemporary democratic hybridization and constitutional retrogression in Israel. We seek to reconstruct the Israeli case as a state of affairs where a strong leadership, coupled with rising political elites, are leading to a wide-ranging political risk to the constitutional liberal-democracy, to an erosion of its democratic institutions, and to an incremental democratic backslide. This Article contributes to the evolving recent literature in comparative constitutional law on the constitutional implications of democratic retrogression by characterizing the Israeli case as one that might be categorized as constitutional retrogression. This, as we argue, carries greater normative and descriptive implications. Descriptively, our analysis sheds new light on Israeli constitutionalism in general and on the constitutional revolution in particular. Instead of regarding the Israeli constitution-making as a western liberal-democratic success story, we argue it is closer to that which is termed in the literature the “Global South.” Normatively, the understanding that the Israeli constitutional order is much more fragile than its prevailing image, prospective constitutional adjudication (and scholarship) should put greater emphasis on Israel’s “institutional constitution”—the constitutional set of norms that protects the democratic rules of the game, elections, separation of powers, representation, etc. Our overall argument is that there is a danger and an ongoing, systematic deterioration of the Israeli constitutional model, which requires a systemic political and juristic respons

    Aeroservoelastic modeling and applications using minimum-state approximations of the unsteady aerodynamics

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    Various control analysis, design, and simulation techniques for aeroelastic applications require the equations of motion to be cast in a linear time-invariant state-space form. Unsteady aerodynamics forces have to be approximated as rational functions of the Laplace variable in order to put them in this framework. For the minimum-state method, the number of denominator roots in the rational approximation. Results are shown of applying various approximation enhancements (including optimization, frequency dependent weighting of the tabular data, and constraint selection) with the minimum-state formulation to the active flexible wing wind-tunnel model. The results demonstrate that good models can be developed which have an order of magnitude fewer augmenting aerodynamic equations more than traditional approaches. This reduction facilitates the design of lower order control systems, analysis of control system performance, and near real-time simulation of aeroservoelastic phenomena
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