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1.
Drawing on survey data collected from chief administrative officers (CAOs) from the largest US cities, this paper analyzes the role of CAO risk perception. Several major questions are asked. How valid are the perceptions of CAOs regarding the level of risks posed to their cities by natural disasters? Do differences in perceptions vary based upon how threatened CAOs say they feel? Do differences in management activities, public procedures, and political concerns result as a consequence of how threatened CAOs say they feel? Do perceptions of threat align with objective vulnerability characteristics? The findings show that there is misperception of risk among CAOs. Risk perceptions influence perceptions as well as management activities, public procedures, and political concerns. 相似文献
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This practice and experience paper describes a robust C++ implementation of several non‐linear solid three‐dimensional deformable object strategies commonly employed in computer graphics, named the Vega finite element method (FEM) simulation library. Deformable models supported include co‐rotational linear FEM elasticity, Saint–Venant Kirchhoff FEM model, mass–spring system and invertible FEM models: neo‐Hookean, Saint–Venant Kirchhoff and Mooney–Rivlin. We provide several timestepping schemes, including implicit Newmark and backward Euler integrators, and explicit central differences. The implementation of material models is separated from integration, which makes it possible to employ our code not only for simulation, but also for deformable object control and shape modelling. We extensively compare the different material models and timestepping schemes. We provide practical experience and insight gained while using our code in several computer animation and simulation research projects. 相似文献
3.
Paul Centore 《Journal of the Society for Information Display》2012,20(4):214-220
Abstract— A control sequence gives the intensities of the primaries for a pixel of a display device. The display gamut, i.e., the set of all the colors that a display can produce, is a zonohedral subset of CIE XYZ space and contains both boundary and interior colors. Displays with four primaries or more exhibit metamerism, in which different control sequences produce colors that appear identical to an observer. This paper shows mathematically that, provided no three primaries are linearly dependent, metamerism can only occur for interior colors. When there are four or more primaries, metamers can always be found for interior colors. A color on the gamut boundary, by contrast, is only produced by a unique control sequence. The proof used for displays can be extended to object‐color solids, to show that optimal colors, which are on the boundary of an object‐color solid, have unique reflectance functions. 相似文献
4.
We describe the design and implementation of system architecture to support object introspection in C++. In this system, information is collected by parsing class declarations, and is used to build a supporting environment for object introspection. Our approach is non‐intrusive because it requires no changes in the original class declarations and libraries; hence, binary compatibility between objects before and after the addition of introspective capability is ensured. This is critical if one wants to integrate third‐party class libraries, which are often supplied as black boxes and allow no modification, into highly dynamic applications. We present two applications: the first is automatic I/O support for C++ objects, and the other is interactive exercise of dynamically loaded C++ class libraries. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
5.
The Demand for Post‐Katrina Disaster Aid: SBA Disaster Loans and Small Businesses in Mississippi
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Following Hurricane Katrina, the United States government provided billions of dollars in loans to repair the damage caused by the hurricane. However, the specifics surrounding demand for these loans and the process of application and approval for Small Business Administration (SBA) loans have yet to be fully examined. We analyse the demand of small businesses for such loans and delve into the factors which are associated with success in obtaining loan funds following disaster. Results indicate several factors are important in all of the stages of the loan process: the income of the business, whether the business had insurance or received money in an insurance claim and the gender of the business owner. 相似文献
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A rigorous validation for the use of a set of linear time‐invariant models as a surrogate in the design of controllers for uncertain nonlinear systems, which are invertible as one‐to‐one operators, such as used in the nonlinear quantitative feedback theory (NLQFT) design methodology has been given by Baños and Bailey. This paper presents a similar validation but weakens the requirement on the invertibility of the nonlinear plant by application of Kakutani's fixed‐point theorem and an incremental gain constraint on the plant within its operational envelope. The set of linear time‐invariant models to be used for design is shown to be an extension (termed here the linear time‐invariant extension—LTIE) of the nonlinear plant restricted to the desired output operating space. A new non‐parametric approach to the modelling of the LTIE is proposed which is based on Fourier transforms of the plant I/O data and which accordingly may be based solely on experimental testing without the need for an explicit parametric plant model. This new approach thus extends the application of robust linear controller design methods (including those of NLQFT) to nonlinear plants with set‐valued (multi‐valued) inverses such as those containing backlash and also to plants for which explicit parametric models are difficult to obtain. The method is illustrated by application of the non‐parametric approach to an NLQFT tracking controller design for a mechanical backlashed servomechanism problem. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
8.
The stabilization of feedforward nonlinear systems subject to hard‐input nonlinearities is a challenging problem due to the presence of input uncertainties. This paper deals with adaptive control of a class of feedforward nonlinear systems driven by unknown dead‐zone inputs. The unknown dead‐zone input nonlinearity is assumed to be either symmetric or non‐symmetric. The control design is based on the combination of the invariant‐manifold stabilization technique with the classical adaptive and robust compensation methods. Simulation results showed that the presence of the dead‐zone inputs in the system dynamics can be handled even for arbitrary large dead‐zone parameters. 相似文献
9.
Edward Boje 《国际强度与非线性控制杂志
》2002,12(4):303-320
》2002,12(4):303-320
This paper discusses multivariable quantitative feedback design through the use of controllers with off‐diagonal elements. Controller design for multivariable plants with significant uncertainty is simpler and potentially less conservative if some sort of dominance is achieved (by reducing the interaction effect of off‐diagonal plant elements) before a diagonal (decentralized) controller design is attempted. Traditional approaches for achieving dominance are not applicable when plant uncertainty must be considered. This paper discusses parallel and series implementations and for the latter, a pseudo‐Gauss elimination approach to the design has been developed. The interaction is measured using the Perron–Frobenius root of an interaction matrix. In some applications, it is possible to trade off individual plant cases against each other in order to reduce to the worst‐case interaction over the entire plant set. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
10.
William Benjamin Andrew Wood Polk S.V.N. Vishwanathan Karthik Ramani 《Computer Graphics Forum》2011,30(7):2097-2106
Segmenting three dimensional objects using properties of heat diffusion on meshes aim to produce salient results. The few existing algorithms based on heat diffusion do not use the full knowledge that can be gained from heat diffusion and are sensitive to varying kinds of perturbations. Our simple algorithm, Heat Walk, converts the implicit information in the heat kernel to explicit knowledge about the pathways for maximum heat flow capacity. We develop a two stage strategy for segmentation. In the first stage we quickly identify regions which are dominated by heat accumulators by employing a greedy algorithm. The second stage partitions out dissipative regions from the previously discovered accumulative regions by using a KL‐divergence based criterion. The resulting algorithm is both independent of human intervention and fast because of the globally aware directed walk along the maximal heat flow capacity. Extensive experimental evidence shows the method is robust to a variety of noise factors including topological short circuits, surface holes, pose variations, variations in tessellation, missing features, scaling, as well as normal and shot noise. Comparison with the Princeton Segmentation Benchmark (PSB) shows that our method is comparable with state of the art segmentation methods and has additional advantages of being robust and self contained. Based upon theoretical insight the convergence and stability of the Heat Walk is shown. 相似文献
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Multidimensional scaling is a must‐have tool for visual data miners, projecting multidimensional data onto a two‐dimensional plane. However, what we see is not necessarily what we think about. In many cases, end‐users do not take care of scaling the projection space with respect to the multidimensional space. Anyway, when using non‐linear mappings, scaling is not even possible. Yet, without scaling geometrical structures which might appear do not make more sense than considering a random map. Without scaling, we shall not make inference from the display back to the multidimensional space. No clusters, no trends, no outliers, there is nothing to infer without first quantifying the mapping quality. Several methods to qualify mappings have been devised. Here, we propose CheckViz, a new method belonging to the framework of Verity Visualization. We define a two‐dimensional perceptually uniform colour coding which allows visualizing tears and false neighbourhoods, the two elementary and complementary types of geometrical mapping distortions, straight onto the map at the location where they occur. As examples shall demonstrate, this visualization method is essential to help users make sense out of the mappings and to prevent them from over interpretations. It could be applied to check other mappings as well. 相似文献
13.
Perceptions of learning effectiveness in M‐learning: scale development and student awareness
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The purpose of this study is to develop a multi‐dimensional scale to measure students' awareness of key competencies for M‐learning and to test its reliability and validity. The Key Competencies of Mobile Learning Scale (KCMLS) was determined via confirmatory factor analysis to have four dimensions: team collaboration, creative thinking, critical thinking and problem solving, and communication. The research subjects are 815 students from the elementary school that participate in M‐learning programme in Taiwan. The research results show that students have better self‐awareness in team collaboration and creative thinking, but have worse self‐awareness in critical thinking and problem solving. This study also found that there was no significant difference between genders in the KCMLS, but students who study in the schools that committed in M‐learning longer have higher awareness in all dimensions than students who study in the schools that committed to M‐learning in fewer years. 相似文献
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In projector applications, the actual display effect is primarily dependent on two aspects: projector performance parameters (intrinsic properties), and projector placement (extrinsic properties). Many studies have been conducted on the impact of the original resolution, illumination, and contrast ratio on projection performance. However, few studies have focused on the influence of extrinsic properties, including the position and orientation of the projector on the projection effect. In this paper, three projection performance evaluation criteria—projection resolution, resolution difference, and projection distance difference—are proposed in terms of extrinsic properties. Based on these evaluation criteria, a projection performance evaluation function was constructed. Through this function, as well as optimization employing the multi‐start and Monte Carlo methods, projector pose parameters corresponding to optimal projection effects can be obtained. Evaluations demonstrated that the proposed projection performance evaluation criteria could correctly describe the impacts of projector placement on projection effects. Projection systems arranged according to the projector pose optimization methods achieved good performance on screens in difference shapes with different numbers of projectors, where the resolution and display improved with no change of projector hardware parameters. The optimal projector poses calculated using these optimization methods can provide theoretical guidance for practical projector placement. 相似文献
15.
Merja Rapeli 《突发事故与危机管理杂志》2017,25(4):389-398
Local actors are crucial in disaster risk management; thus, their capacities should be assessed periodically. In this study, local social services’ preparedness plans were assessed using Emergency Management Program Measurement and quantitative document analysis. The specific aim was to study how social service areas of various sizes were prepared for disasters in Finland. The results showed that disaster risk management capacity varied significantly between large and small service areas. Larger areas were better prepared for supporting management, and had better procedures to activate their response, modern public information and deeper cooperation with the private sector and the civil society. The differences might derive from the fact that large areas have more resources allocated to disaster risk management. 相似文献
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This paper presents an online personalised non‐photorealistic rendering (NPR) technique for 3D models generated from interactively sketched input. This technique has been integrated into a sketch‐based modelling system. It lets users interact with computers by drawing naturally, without specifying the number, order, or direction of strokes. After sketches are interpreted as 3D objects, they can be rendered with personalised drawing styles so that the reconstructed 3D model can be presented in a sketchy style similar in appearance to what have been drawn for the 3D model. This technique captures the user's drawing style without using template or prior knowledge of the sketching style. The personalised rendering style can be applied to both visible and initially invisible geometry. The rendering strokes are intelligently selected from the input sketches and mapped to edges of the 3D object. In addition, non‐geometric information such as surface textures can be added to the recognised object in different sketching modes. This will integrate sketch‐based incremental 3D modelling and NPR into conceptual design. 相似文献
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本文介绍在无法通过局域网传递数据的管理信息系统中,结合实际经验,对安全性、稳定性、可操作性综合考虑,介绍一种通过Email传递信息的代替方法。 相似文献
19.
Iasson Karafyllis 《国际强度与非线性控制杂志
》2006,16(4):191-214
》2006,16(4):191-214
In this paper the notions of non‐uniform in time robust global asymptotic output stability (RGAOS) and input‐to‐output stability (IOS) for discrete‐time systems are studied. Characterizations as well as links between these notions are provided. Particularly, it is shown that a discrete‐time system with continuous dynamics satisfies the non‐uniform in time IOS property if and only if the corresponding unforced system is non‐uniformly in time RGAOS. Necessary and sufficient conditions for the solvability of the robust output feedback stabilization (ROFS) problem are also given. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
20.
Boris Porfiriev 《突发事故与危机管理杂志》2005,13(4):145-152
In recent years the EU has been increasingly involved in development and implementation of crisis policy as a component of its development and security policy. This process is seriously complicated by the EU architects, who had never conceived it as a crisis management institute. Therefore they failed to design built‐in organisational capacities into the Union to mitigate and respond to crises. In addition, the EU‐agreed overarching concept of crisis as such and EU crisis in particular is missing. Both issues remain a primary question on research and policy agendas. Provided below are some of the author's considerations and comments on these issues. It is argued that, despite the existing divergence in crisis interpretations in the EU, coherent conceptualisation is possible and approaches to this are introduced. Practical implications of generic crisis conceptualisation for EU crisis management policy are analysed. Within this context three major lessons from international experience, including that from the USA and Russia, are emphasised. These concern the issues of organisational flexibility, learning from earlier major crises and comprehensive training of crisis decision units critical for efficient crisis management policy. 相似文献