We present a tool for querying a set of points for geometric shapes. This tool was developed as part of a larger project studying the architecture of 13th century French churches. We present a query language for speci...
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We present a tool for querying a set of points for geometric shapes. This tool was developed as part of a larger project studying the architecture of 13th century French churches. We present a query language for specifying shapes. We describe an implementation of the tool that optimizes and executes shape queries. We describe the performance of the tool, and show examples of how it can be used to analyze building floorplans. The tool is available for, download over the internet.
The paper considers the large-time behaviour of Positive solutions of the equation partial derivative(u + u(p))/partial derivative t = partial derivative 2u/partial derivative x2 - partial derivative u/partial derivat...
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The paper considers the large-time behaviour of Positive solutions of the equation partial derivative(u + u(p))/partial derivative t = partial derivative 2u/partial derivative x2 - partial derivative u/partial derivative x, p > 0 with - infinity < x < infinity and t greater-than-or-equal-to 0, for pulse-type initial data. In suitably scaled variables this equation models the one-dimensional flow of a solute through a porous medium with the solute undergoing absorption by the solid matrix of the medium. With the total mass both absorbed and in solution invariant, it is shown that the asymptotic solution depends crucially on the value of p. For p > 2 the solution approaches the symmetric solution of the linear heat equation centred on x = t, while for p = 2 this becomes asymmetric due to the effect of nonlinearity. For 1 < p < 2 convection dominates at large time and the solution approaches the form of an asymmetric pulse moving at unit speed along the positive x-axis. Diffusion effects are confined to regions near the leading and trailing edges of the pulse. For 0 < p < 1 the pulse is still convection-dominated but it no longer moves under a simple translation. Again diffusion only becomes important near the leading and trailing edges. It is shown that for p greater-than-or-equal-to 2 the asymptotic solutions are uniformly valid in x but for 0 < p < 2 convection-dominated outer solutions have to be supplemented by diffusion boundary layers. In this latter case uniformly-valid composite solutions can be constructed. Finally our asymptotic analyses for the various values of p are compared with numerical solutions of the initial-value problem.
A tutorial and diagnostic visual tool is used to compute a set of strange attractors for a double oscillator. The tool provides a visual environment to detect chaotic behaviour from a time series. Here, computation an...
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A tutorial and diagnostic visual tool is used to compute a set of strange attractors for a double oscillator. The tool provides a visual environment to detect chaotic behaviour from a time series. Here, computation and visualization are coupled together in a single environment. Common techniques to detect chaos involve the visualization of phase portraits and Poincare maps, apart from the computation of fractal dimension, Lyapunov exponents and Fast Fourier Transforms (FFT). Results from these computations must be viewed graphically before a decision about the chaotic behaviour of a system can be made. In many cases, the use of a single technique may not always guarantee conclusive evidence that a system's behaviour is chaotic. A few numerical integration schemes are built into the environment to generate a time series. The environment is demonstrated first with the use of the Duffing oscillator and the chaotic behaviour of a double oscillator is then presented, which provides an interesting set of strange attractors. (C) 1997 Elsevier Science Ltd.
The design of an autonomous robot architecture is analyzed in light of the cognitive psychological, neuroscientific, and ethological studies that influenced its development. Motor schema-based navigation and its relat...
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The design of an autonomous robot architecture is analyzed in light of the cognitive psychological, neuroscientific, and ethological studies that influenced its development. Motor schema-based navigation and its relationship to models of detour behavior in amphibians is described. Application of the action-perception cycle in the context of action-oriented perception is discussed, with particular emphasis on the role of expectations as focus-of-attention mechanisms. The process of homeostatic control as a means of dynamically modifying motor behavior based on internal sensing is also described. These approaches are substantiated throughout with simulation studies and actual mobile robot experiments.< >
作者：
CLARKE, JHOcean Mapping Group
Department of Surveying Engineering University of New Brunswick Fredericton NB Canada
While the average seafloor backscatter strength within a narrow range of grazing angles can be used as a firstorder classification tool, this technique often fails to distinguish seafloors of known differing geologica...
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While the average seafloor backscatter strength within a narrow range of grazing angles can be used as a firstorder classification tool, this technique often fails to distinguish seafloors of known differing geological character. In order to resolve such ambiguities, it is necessary to examine the variation in backscatter strength as a function of grazing angle. For this purpose, a series of multiply overlapping GLORIA sidescan sonar images (6.5 kHz) have been obtained in water depths ranging from 1000 to 2500 m. To constrain the placement of acoustic backscatter measurements and to measure the true impinging angle of the incident wave, the corresponding seafloor was simultaneously surveyed using the Seabeam multibeam system. As a result of the multiple overlap, the angular response of seafloor backscatter strength may be derived for regions much smaller than the swath width. By using the derived angular response of seafloor backscatter strength in regions for which sediment samples exist, an empirical seafloor classification scheme is proposed based on the shape, variance, and magnitude of the angular response. Because of the observed variability in the shape of the angular response with differing seafloor types, routine normalization of single-pass swath data to an equivalent single grazing angle image cannot be achieved. As a result, for the case of single-pass surveys, confident seafloor classification may only be possible for regions approaching the scale of the swath width.
The purpose of this work is to provide a parallel programming environment for symbolic applications suited to run on Distributed Memory Parallel Systems (DMPS). This paper describes the implementation of such an envir...
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The purpose of this work is to provide a parallel programming environment for symbolic applications suited to run on Distributed Memory Parallel Systems (DMPS). This paper describes the implementation of such an environment that is based on Sabot's Paralation model (in particular its LISP implementation, Paralation LISP). In our opinion, the clear distinction between the communication and computation aspects in the Paralation model allows a clearer and easier exploitation of the opportunities of parallelism in symbolic applications. Furthermore, the simple semantics of its parallel constructs seem well suited to run on a community of loosely coupled LISP interpreters. We chose to implement the Paralation model constructs on the top of the Parallel Virtual Machine (PVM) package because this tool allows one to have a cheap virtual distributed memory parallel machine simply by using some LAN interconnected powerful workstations. (C) 1997 Elsevier Science Limited.
The problem of estimating the parameters of complex-valued sinusoidal signals (cisoids, for short) from data corrupted by colored noise occurs in many signal processing applications, We present a simple formula for th...
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The problem of estimating the parameters of complex-valued sinusoidal signals (cisoids, for short) from data corrupted by colored noise occurs in many signal processing applications, We present a simple formula for the asymptotic (large-sample) Cramer-Rao bound (CRB) matrix associated with this problem. The maximum likelihood method (MLM), which estimates both the signal and noise parameters, attains the performance corresponding to the asymptotic CRB, as the sample length increases. More interestingly, we show that a computationally much simpler nonlinear least-squares method (NLSM), which estimates the signal parameters only, achieves the same performance in large samples.
In this paper, we examine ''program adjustment'', a formal and practical approach to developing correct concurrent programs, by automatically adjusting an imperfect program to satisfy given constraints...
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In this paper, we examine ''program adjustment'', a formal and practical approach to developing correct concurrent programs, by automatically adjusting an imperfect program to satisfy given constraints. A concurrent program is modeled by a finite state process, and program adjustment to satisfy temporal logic constraints is formalized as the synthesis of an arbiter process which partially serializes target (i.e., imperfect) processes to remove harmful nondeterministic behaviors. Compositional adjustment is also proposed for large-scale compound target processes, using process equivalence theory. We have developed a computer-aided programming environment on the parallel computer Multi-PSI, called MENDELS ZONE, that adopts this compositional adjustment. Adjusted programs can be compiled into the kernel language (KL1) and executed on Multi-PSI.
In this paper, a framework for maintaining control of and analyzing object-oriented system specifications of real-time systems by using a set of metrics covering technical, cognitive, and process-oriented views is pre...
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In this paper, a framework for maintaining control of and analyzing object-oriented system specifications of real-time systems by using a set of metrics covering technical, cognitive, and process-oriented views is presented. The indicators defined can be used for monitoring the evolution of system quality and for effort prediction. The use of metrics for the estimation of reusability, verifiability, and testability is analyzed. The metric framework is integrated in a CASE tool named TOOMS, which is based on TROL, a dual object-oriented language with both descriptive and operational capabilities. TOOMS allows one to describe the system at different levels of structural abstractions and at different levels of specification detail, such as many other languages and models for teal-time systems (e.g., OSDL, ObjectTime, ObjectChart). According to this, the metrics proposed are capable of producing estimations at each level of system specification, thus allowing incremental specification/metrication. The metric framework must be regarded as a support for controlling the process of software development in order to guarantee the final quality.
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