bluuebunny/crossref_metadata_2025 huggingface dataset:
Versatility and Unix semantics in namespace unification
Authors: Wright Charles P. , Dave Jay , Gupta Puja , Krishnan Harikesavan , Quigley David P. , Zadok Erez , Zubair Mohammad Nayyer
Published: July 2006

Administrators often prefer to keep related sets of files in different locations or media, as it is easier to maintain them separately. Users, however, prefer to see all files in one location for convenience. One solution that accommodates both needs is virtual namespace unification---providing a merged view of several directories without physically merging them. For example, namespace unification can merge the contents of several CD-ROM images without unpacking them, merge binary directories from different packages, merge views from several file servers, and more. Namespace unification can also enable snapshotting by marking some data sources read-only and then utilizing copy-on-write for the read-only sources. For example, an OS image may be contained on a read-only CD-ROM image---and the user's configuration, data, and programs could be stored in a separate read-write directory. With copy-on-write unification, the user need not be concerned about the two disparate file systems.It is difficult to maintain Unix semantics while offering a versatile namespace unification system. Past efforts to provide such unification often compromised on the set of features provided or Unix compatibility---resulting in an incomplete solution that users could not use.We designed and implemented a versatile namespace unification system called
Unionfs
. Unionfs maintains Unix semantics while offering advanced namespace unification features: dynamic insertion and removal of namespaces at any point in the merged view, mixing read-only and read-write components, efficient in-kernel duplicate elimination, NFS interoperability, and more. Since releasing our Linux implementation, it has been used by thousands of users and over a dozen Linux distributions, which helped us discover and solve many practical problems.
Point-based multiscale surface representation
Authors: Pauly Mark , Kobbelt Leif P. , Gross Markus
Published: July 2006

In this article we present a new multiscale surface representation based on point samples. Given an unstructured point cloud as input, our method first computes a series of point-based surface approximations at successively higher levels of smoothness, that is, coarser scales of detail, using geometric low-pass filtering. These point clouds are then encoded relative to each other by expressing each level as a scalar displacement of its predecessor. Low-pass filtering and encoding are combined in an efficient multilevel projection operator using local weighted least squares fitting.Our representation is motivated by the need for higher-level editing semantics which allow surface modifications at different scales. The user would be able to edit the surface at different approximation levels to perform coarse-scale edits on the whole model as well as very localized modifications on the surface detail. Additionally, the multiscale representation provides a separation in geometric scale which can be understood as a spectral decomposition of the surface geometry. Based on this observation, advanced geometric filtering methods can be implemented that mimic the effects of Fourier filters to achieve effects such as smoothing, enhancement, or band-bass filtering.
A tangent subdivision scheme
Authors: Vanraes Evelyne , Bultheel Adhemar
Published: July 2006

In this article, we propose a new subdivision scheme based on uniform Powell-Sabin spline subdivision. It belongs to the class of vector subdivision schemes; for each vertex, we have three control points that form a control triangle tangent to the surface instead of one control point. The main advantage of this scheme is that we can choose the values of the normals in the initial vertices which results in more design possibilities. At first sight, it is an approximating scheme because the control points change each iteration. However, the point where the control triangle is tangent to the surface remains the same. Therefore, it is an interpolating scheme. In the regular regions, we use the uniform Powell-Sabin rules, and we develop additional subdivision rules for the new vertices in the neighborhood of extraordinary vertices. The scheme yieldsC1continuous surfaces. We also do the convergence analysis based on the eigenproperties of the subdivision matrix and the properties of the characteristic map.
Accurate detection of symmetries in 3D shapes
Authors: Martinet Aurélien , Soler Cyril , Holzschuch Nicolas , Sillion François X.
Published: July 2006

We propose an automatic method for finding symmetries of 3D shapes, that is, isometric transforms which leave a shape globally unchanged. These symmetries are deterministically found through the use of an intermediate quantity: the generalized moments. By examining the extrema and spherical harmonic coefficients of these moments, we recover the parameters of the symmetries of the shape. The computation for large composite models is made efficient by using this information in an incremental algorithm capable of recovering the symmetries of a whole shape using the symmetries of its subparts. Applications of this work range from coherent remeshing of geometry with respect to the symmetries of a shape to geometric compression, intelligent mesh editing, and automatic instantiation.
Managerial IT unconsciousness
Authors: Avison David , Gregor Shirley , Wilson David
Published: July 2006

A poorly designed, carelessly implemented, irresponsibly managed system can lead to company failure, along with IT failure.
Semantics to energize the full services spectrum
Authors: Sheth Amit , Verma Kunal , Gomadam Karthik
Published: July 2006

Using an ontological approach to better exploit services at the technical and business levels.
Resource planning for business services
Authors: Dietrich Brenda
Published: July 2006

Over the past several decades mathematical models of supply chains have been developed and used for resource planning. Significant gains in supply chain efficiency have been attributed to the use of such models, together with the supporting IT infrastructure. Manufacturing resource planning (MRP), which automated the calculations of material requirements within manufacturing, evolved into enterprise resource planning (ERP), which monitors manufacturing enterprise processes and provides an information base for mathematically based advanced planning.
The evolution and discovery of services science in business schools
Authors: Bitner Mary Jo , Brown Stephen W.
Published: July 2006

The pioneering efforts of Arizona State University illustrate what can be accomplished when universities worldwide address the need to create comprehensive interdisciplinary curricula for services science.
Toy projects considered harmful
Authors: Martin Fred
Published: July 2006

It is valuable to improve upon the sample code we provide to students. But the deeper challenge is to create a context in which student programming matters.
Improving the performance of reduction to Hessenberg form
Authors: Quintana-Ortí Gregorio , Geijn Robert van de
Published: July 2006

In this article, a modification of the blocked algorithm for reduction to Hessenberg form is presented that improves performance by shifting more computation from less efficient matrix-vector operations to highly efficient matrix-matrix operations. Significant performance improvements are reported relative to the performance achieved by the current LAPACK implementation.
Simultaneous measurement of steering performance and perceived heading on a curving path
Authors: Kelly Jonathan W. , Beall Andrew C. , Loomis Jack M. , Smith Roy S. , Macuga Kristen L.
Published: July 2006

The ability to judge heading (direction of travel) has been the focus of much research, but a role for perceived heading in steering has not been firmly established. Subjects steered down a road consisting of straight and curved segments and made heading judgments along the way. Heading judgments while traversing curved road segments were biased in the direction of the curve by up to 5° and position errors on the same curved roads were highly correlated with heading biases. This correlation was revealed by the simultaneous measurement of steering performance and perceived heading.
Teaching proofs and algorithms in discrete mathematics with online visual logic puzzles
Authors: Cigas John , Hsin Wen-Jung
Published: July 2006

Visual logic puzzles provide a fertile environment for teaching multiple topics in discrete mathematics. Many puzzles can be solved by the repeated application of a small, finite set of strategies. Explicitly reasoning from a strategy to a new puzzle state illustrates theorems, proofs, and logic principles. These provide valuable, concrete examples, in addition to the algebraic proofs that make up most of the examples in textbooks. Creating specialized, pedagogical applets allows more automation of repetitive tasks as well as a framework for discussing and implementing algorithms for solving the puzzles. One such applet is presented here and several possible exercises using it are described.
Constructing contracts
Authors: Gegg-Harrison Timothy S.
Published: July 2006

Although computer scientists understand the importance of discrete mathematics to the foundations of their field, computer science (CS) students do not always see the relevance. Thus, it is important to find a way to show students its relevance. The concept of program correctness is generally taught as an activity independent of the programming process, hence many CS students perceive it as unnecessary, and even irrelevant. The concept of contracts, on the other hand, is generally taught as an integral part of the programming process. Most CS students have little difficulty understanding the need to establish contracts via preconditions and postconditions. In order to improve teaching program correctness concepts, we implemented ProVIDE, an enhanced integrated development environment (IDE). ProVIDE assists student programmers in contract construction. Rather than asking for both a precondition and postcondition for each of the student's methods, ProVIDE asks the student to simply supply a postcondition. ProVIDE then helps the student construct the appropriate precondition by leading him or her through an axiomatic proof of the method's correctness. Thus, the proof of of the method's correctness is a side-effect of the student's need to construct an appropriate precondition.
Realizing the promise of visualization in the theory of computing
Authors: Cogliati Joshua J. , Goosey Frances W. , Grinder Michael T. , Pascoe Bradley A. , ROSS Rockford J. , Williams Cheston J.
Published: July 2006

Progress on a hypertextbook on the theory of computing is presented. The hypertextbook is a novel teaching and learning resource built around web technologies that incorporates text, sound, pictures, illustrations, slide shows, video clips, and---most importantly---active learning models of the key concepts of the theory of computing into an integrated resource. Active learning models currently exist for finite state automata, regular expressions, regular grammars, the pumping lemma for regular languages, context- free grammars, LL(1) parsing, and program execution. The seamless interweaving of these components into a browser-ready whole will help realize the goal of integrating visualization aids into theory courses.
Guided visibility sampling
Authors: Wonka Peter , Wimmer Michael , Zhou Kaichi , Maierhofer Stefan , Hesina Gerd , Reshetov Alexander
Published: July 2006

This paper addresses the problem of computing the triangles visible from a region in space. The proposed aggressive visibility solution is based on stochastic ray shooting and can take any triangular model as input. We do not rely on connectivity information, volumetric occluders, or the availability of large occluders, and can therefore process any given input scene. The proposed algorithm is practically memoryless, thereby alleviating the large memory consumption problems prevalent in several previous algorithms. The strategy of our algorithm is to use ray mutations in ray space to cast rays that are likely to sample new triangles. Our algorithm improves the sampling efficiency of previous work by over two orders of magnitude.
Recursive Wang tiles for real-time blue noise
Authors: Kopf Johannes , Cohen-Or Daniel , Deussen Oliver , Lischinski Dani
Published: July 2006

Well distributed point sets play an important role in a variety of computer graphics contexts, such as anti-aliasing, global illumination, halftoning, non-photorealistic rendering, point-based modeling and rendering, and geometry processing. In this paper, we introduce a novel technique for rapidly generating large point sets possessing a blue noise Fourier spectrum and high visual quality. Our technique generates non-periodic point sets, distributed over arbitrarily large areas. The local density of a point set may be prescribed by an arbitrary target density function, without any preset bound on the maximum density. Our technique is deterministic and tile-based; thus, any local portion of a potentially infinite point set may be consistently regenerated as needed. The memory footprint of the technique is constant, and the cost to generate any local portion of the point set is proportional to the integral over the target density in that area. These properties make our technique highly suitable for a variety of real-time interactive applications, some of which are demonstrated in the paper.Our technique utilizes a set of carefully constructed
progressive
and
recursive
blue noise Wang tiles. The use of Wang tiles enables the generation of infinite non-periodic tilings. The progressive point sets inside each tile are able to produce spatially varying point densities. Recursion allows our technique to adaptively subdivide tiles only where high density is required, and makes it possible to zoom into point sets by an arbitrary amount, while maintaining a constant apparent density.
Image deformation using moving least squares
Authors: Schaefer Scott , McPhail Travis , Warren Joe
Published: July 2006

We provide an image deformation method based on Moving Least Squares using various classes of linear functions including affine, similarity and rigid transformations. These deformations are realistic and give the user the impression of manipulating real-world objects. We also allow the user to specify the deformations using either sets of points or line segments, the later useful for controlling curves and profiles present in the image. For each of these techniques, we provide simple closed-form solutions that yield fast deformations, which can be performed in real-time.
SmoothSketch
Authors: Karpenko Olga A. , Hughes John F.
Published: July 2006

We introduce SmoothSketch---a system for inferring plausible 3D free-form shapes from visible-contour sketches. In our system, a user's sketch need not be a simple closed curve as in Igarashi's Teddy [1999], but may have cusps and T-junctions, i.e., endpoints of hidden parts of the contour. We follow a process suggested by Williams [1994] for inferring a smooth solid shape from its visible contours: completion of hidden contours, topological shape reconstruction, and smoothly embedding the shape via relaxation. Our main contribution is a practical method to go from a contour drawing to a fairly smooth surface with that drawing as its visible contour. In doing so, we make several technical contributions: • extending Williams' and Mumford's work [Mumford 1994] on figural completion of hidden contours containing T-junctions to contours containing cusps as well, • characterizing a class of visible-contour drawings for which inflation can be proved possible, • finding a topological embedding of the combinatorial surface that Williams creates from the figural completion, and • creating a fairly smooth solid shape by smoothing the topological embedding using a mass-spring system.We handle many kinds of drawings (including objects with holes), and the generated shapes are plausible interpretations of the sketches. The method can be incorporated into any sketch-based free-form modeling interface like Teddy.
Point-sampled cell complexes
Authors: Adamson Anders , Alexa Marc
Published: July 2006

A piecewise smooth surface, possibly with boundaries, sharp edges, corners, or other features is defined by a set of samples. The basic idea is to model surface patches, curve segments and points explicitly, and then to glue them together based on explicit connectivity information. The geometry is defined as the set of stationary points of a projection operator, which is generalized to allow modeling curves with samples, and extended to account for the connectivity information. Additional tangent constraints can be used to model shapes with continuous tangents across edges and corners.
Backward compatible high dynamic range MPEG video compression
Authors: Mantiuk Rafał , Efremov Alexander , Myszkowski Karol , Seidel Hans-Peter
Published: July 2006

To embrace the imminent transition from traditional low-contrast video (LDR) content to superior high dynamic range (HDR) content, we propose a novel backward compatible HDR video compression (HDR MPEG) method. We introduce a compact reconstruction function that is used to decompose an HDR video stream into a residual stream and a standard LDR stream, which can be played on existing MPEG decoders, such as DVD players. The reconstruction function is finely tuned to the content of each HDR frame to achieve strong decorrelation between the LDR and residual streams, which minimizes the amount of redundant information. The size of the residual stream is further reduced by removing invisible details prior to compression using our HDR-enabled filter, which models luminance adaptation, contrast sensitivity, and visual masking based on the HDR content. Designed especially for DVD movie distribution, our HDR MPEG compression method features low storage requirements for HDR content resulting in a 30% size increase to an LDR video sequence. The proposed compression method does not impose restrictions or modify the appearance of the LDR or HDR video. This is important for backward compatibility of the LDR stream with current DVD appearance, and also enables independent fine tuning, tone mapping, and color grading of both streams.
Coded exposure photography
Authors: Raskar Ramesh , Agrawal Amit , Tumblin Jack
Published: July 2006

In a conventional single-exposure photograph, moving objects or moving cameras cause motion blur. The exposure time defines a temporal box filter that smears the moving object across the image by convolution. This box filter destroys important high-frequency spatial details so that deblurring via deconvolution becomes an ill-posed problem.Rather than leaving the shutter open for the entire exposure duration, we "flutter" the camera's shutter open and closed during the chosen exposure time with a binary pseudo-random sequence. The flutter changes the box filter to a broad-band filter that preserves high-frequency spatial details in the blurred image and the corresponding deconvolution becomes a well-posed problem. We demonstrate that manually-specified point spread functions are sufficient for several challenging cases of motion-blur removal including extremely large motions, textured backgrounds and partial occluders.
Efficient simulation of large bodies of water by coupling two and three dimensional techniques
Authors: Irving Geoffrey , Guendelman Eran , Losasso Frank , Fedkiw Ronald
Published: July 2006

We present a new method for the efficient simulation of large bodies of water, especially effective when three-dimensional surface effects are important. Similar to a traditional two-dimensional height field approach, most of the water volume is represented by tall cells which are assumed to have linear pressure profiles. In order to avoid the limitations typically associated with a height field approach, we simulate the entire top surface of the water volume with a state of the art, fully three-dimensional Navier-Stokes free surface solver. Our philosophy is to use the best available method near the interface (in the three-dimensional region) and to coarsen the mesh away from the interface for efficiency. We coarsen with tall, thin cells (as opposed to octrees or AMR), because they maintain good resolution horizontally allowing for accurate representation of bottom topography.
Generalized wavelet product integral for rendering dynamic glossy objects
Authors: Sun Weifeng , Mukherjee Amar
Published: July 2006

We consider real-time rendering of dynamic glossy objects with realistic shadows under distant all-frequency environment lighting. Previous PRT approaches pre-compute light transport for a fixed scene and cannot account for cast shadows on high-glossy objects occluded by dynamic neighbors. In this paper, we extend double/triple product integral to
generalized multi-function product integral
. We represent shading integral at each vertex as the product integral of multiple functions, involving the lighting, BRDF, local visibility and dynamic occlusions. Our main contribution is a new mathematical representation and analysis of multi-function product integral in the wavelet domain. We show that multi-function product integral in the primal corresponds to the summation of the product of basis coefficients and integral coefficients. We propose a novel
generalized Haar integral coefficient theorem
to evaluate arbitrary Haar integral coefficients. We present an efficient sub-linear algorithm to render dynamic glossy objects under time-variant all-frequency lighting and arbitrary view conditions in a few seconds on a commodity CPU, orders of magnitude faster than previous techniques. To further accelerate shadow computation, we propose a Just-in-time Radiance Transfer (JRT) technique. JRT is a new generalization to PRT for dynamic scenes. It is compact and flexible, and supports glossy materials. By pre-computing radiance transfer vectors at runtime, we demonstrate rendering dynamic view-dependent all-frequency shadows in real-time.
Precomputed acoustic transfer
Authors: James Doug L. , Barbič Jernej , Pai Dinesh K.
Published: July 2006

Simulating sounds produced by realistic vibrating objects is challenging because sound radiation involves complex diffraction and interreflection effects that are very perceptible and important. These wave phenomena are well understood, but have been largely ignored in computer graphics due to the high cost and complexity of computing them at audio rates.We describe a new algorithm for real-time synthesis of realistic sound radiation from rigid objects. We start by precomputing the linear vibration modes of an object, and then relate each mode to its sound pressure field, or acoustic transfer function, using standard methods from numerical acoustics. Each transfer function is then approximated to a specified accuracy using low-order multi-pole sources placed near the object. We provide a low-memory, multilevel, randomized algorithm for optimized source placement that is suitable for complex geometries. At runtime, we can simulate new interaction sounds by quickly summing contributions from each mode's equivalent multipole sources. We can efficiently simulate global effects such as interreflection and changes in sound due to listener location. The simulation costs can be dynamically traded-off for sound quality. We present several examples of sound generation from physically based animations.
Acquiring scattering properties of participating media by dilution
Authors: Narasimhan Srinivasa G. , Gupta Mohit , Donner Craig , Ramamoorthi Ravi , Nayar Shree K. , Jensen Henrik Wann
Published: July 2006

The visual world around us displays a rich set of volumetric effects due to participating media. The appearance of these media is governed by several physical properties such as particle densities, shapes and sizes, which must be input (directly or indirectly) to a rendering algorithm to generate realistic images. While there has been significant progress in developing rendering techniques (for instance, volumetric Monte Carlo methods and analytic approximations), there are very few methods that measure or estimate these properties for media that are of relevance to computer graphics. In this paper, we present a simple device and technique for robustly estimating the properties of a broad class of participating media that can be either (a) diluted in water such as juices, beverages, paints and cleaning supplies, or (b) dissolved in water such as powders and sugar/salt crystals, or (c) suspended in water such as impurities. The key idea is to dilute the concentrations of the media so that single scattering effects dominate and multiple scattering becomes negligible, leading to a simple and robust estimation algorithm. Furthermore, unlike previous approaches that require complicated or separate measurement setups for different types or properties of media, our method and setup can be used to measure media with a complete range of absorption and scattering properties from a single HDR photograph. Once the parameters of the diluted medium are estimated, a volumetric Monte Carlo technique may be used to create renderings of any medium concentration and with multiple scattering. We have measured the scattering parameters of forty commonly found materials, that can be immediately used by the computer graphics community. We can also create realistic images of combinations or mixtures of the original measured materials, thus giving the user a wide flexibility in making realistic images of participating media.
Simulating multiple scattering in hair using a photon mapping approach
Authors: Moon Jonathan T. , Marschner Stephen R.
Published: July 2006

Simulating multiple scattering correctly is important for accurate rendering of hair. However, a volume of hair is a difficult scene to simulate because scattering from an individual fiber is very structured and forward directed, and because the radiance distributions that arise from many such scattering events remain quite directional. For these reasons, previous methods cannot compute accurate images substantially faster than Monte Carlo path tracing.This paper proposes a new physically accurate method for rendering hair that is based on previous volumetric photon mapping methods. The first pass generates a photon map by tracing particles through the hair geometry, depositing them along paths rather than at scattering events. The second pass ray traces the hair, computing direct illumination and looking up indirect radiance in the photon map. Photons are stored and looked up in 5D position-direction space to allow for the very directional radiance distributions that occur in hair. Together with a new radiance caching method for fibers, our method simulates difficult scattering problems in hair efficiently and with low noise.The new algorithm is validated against path tracing and also compared with a photograph of light scattering in real hair.
Editing arbitrarily deforming surface animations
Authors: Kircher Scott , Garland Michael
Published: July 2006

Deforming surfaces, such as cloth, can be generated through physical simulation, morphing, and even video capture. Such data is currently very difficult to alter after the generation process is complete, and data generated for one purpose generally cannot be adapted to other uses. Such adaptation would be extremely useful, however. Being able to take cloth captured from a flapping flag and attach it to a character to make a cape, or enhance the wrinkles on a simulated garment, would greatly enhance the usability and re-usability of deforming surface data. In addition, it is often necessary to cleanup or "tweak" simulation results. Doing this by editing each frame individually is a very time consuming and tedious process. Extensive research has investigated how to edit and re-use skeletal motion capture data, but very little has addressed completely non-rigid deforming surfaces. We have developed a novel method that now makes it easy to edit such arbitrary deforming surfaces. Our system enables global signal processing, direct manipulation, multiresolution embossing, and constraint editing on arbitrarily deforming surfaces, such as simulated cloth, motion-captured cloth, morphs, and other animations. The foundation of our method is a novel time-varying multiresolution transform, which adapts to the changing geometry of the surface in a temporally coherent manner.
A fast multigrid algorithm for mesh deformation
Authors: Shi Lin , Yu Yizhou , Bell Nathan , Feng Wei-Wen
Published: July 2006

In this paper, we present a multigrid technique for efficiently deforming large surface and volume meshes. We show that a previous least-squares formulation for distortion minimization reduces to a Laplacian system on a general graph structure for which we derive an analytic expression. We then describe an efficient multigrid algorithm for solving the relevant equations. Here we develop novel prolongation and restriction operators used in the multigrid cycles. Combined with a simple but effective graph coarsening strategy, our algorithm can outperform other multigrid solvers and the factorization stage of direct solvers in both time and memory costs for large meshes. It is demonstrated that our solver can trade off accuracy for speed to achieve greater interactivity, which is attractive for manipulating large meshes. Our multigrid solver is particularly well suited for a mesh editing environment which does not permit extensive precomputation. Experimental evidence of these advantages is provided on a number of meshes with a wide range of size. With our mesh deformation solver, we also successfully demonstrate that visually appealing mesh animations can be generated from both motion capture data and a single base mesh even when they are inconsistent.
Locally adapted hierarchical basis preconditioning
Authors: Szeliski Richard
Published: July 2006

This paper develops locally adapted hierarchical basis functions for effectively preconditioning large optimization problems that arise in computer graphics applications such as tone mapping, gradient-domain blending, colorization, and scattered data interpolation. By looking at the local structure of the coefficient matrix and performing a recursive set of variable eliminations, combined with a simplification of the resulting coarse level problems, we obtain bases better suited for problems with inhomogeneous (spatially varying) data, smoothness, and boundary constraints. Our approach removes the need to heuristically adjust the optimal number of preconditioning levels, significantly outperforms previously proposed approaches, and also maps cleanly onto data-parallel architectures such as modern GPUs.
Resolving surface collisions through intersection contour minimization
Authors: Volino Pascal , Magnenat-Thalmann Nadia
Published: July 2006

Robust handling of collisions on non-oriented deformable surfaces requires advanced methods for recovering intersecting surfaces. We present a novel method that resolves intersections between two intersecting surface regions by inducing relative displacements which minimize the length of the intersection contour between them. This method, which does not rely on intersection regions, has a broader application field than existing methods, and its implementation is also much simpler, allowing integration into most existing collision response schemes. We demonstrate the efficiency of this method through examples in the context of cloth simulation.
Manga colorization
Authors: Qu Yingge , Wong Tien-Tsin , Heng Pheng-Ann
Published: July 2006

This paper proposes a novel colorization technique that propagates color over regions exhibiting pattern-continuity as well as intensity-continuity. The proposed method works effectively on colorizing black-and-white manga which contains intensive amount of strokes, hatching, halftoning and screening. Such fine details and discontinuities in intensity introduce many difficulties to intensity-based colorization methods. Once the user scribbles on the drawing, a local, statistical based pattern feature obtained with Gabor wavelet filters is applied to measure the pattern-continuity. The boundary is then propagated by the level set method that monitors the pattern-continuity. Regions with open boundaries or multiple disjointed regions with similar patterns can be sensibly segmented by a single scribble. With the segmented regions, various colorization techniques can be applied to replace colors, colorize with stroke preservation, or even convert pattern to shading. Several results are shown to demonstrate the effectiveness and convenience of the proposed method.
Accessorizing
Authors: O'Hanlon Charlene
Published: July 2006

The stand came with a batter paddle and a dough hook, both of which have been put to good use.
Untangling Enterprise Java
Authors: Richardson Chris
Published: July 2006

Separation of concerns is one of the oldest concepts in computer science. The term was coined by Dijkstra in 1974.1 It is important because it simplifies software, making it easier to develop and maintain. Separation of concerns is commonly achieved by decomposing an application into components. There are, however, crosscutting concerns, which span (or cut across) multiple components. These kinds of concerns cannot be handled by traditional forms of modularization and can make the application more complex and difficult to maintain.
AI Gets a Brain
Authors: Barr Jeff , Cabrera Luis Felipe
Published: July 2006

In the 50 years since John McCarthy coined the term artificial intelligence, much progress has been made toward identifying, understanding, and automating many classes of symbolic and computational problems that were once the exclusive domain of human intelligence. Much work remains in the field because humans still significantly outperform the most powerful computers at completing such simple tasks as identifying objects in photographs - something children can do even before they learn to speak.
The Network’s New Role
Authors: Anthias Taf , Sankar Krishna
Published: July 2006

Companies have always been challenged with integrating systems across organizational boundaries. With the advent of Internet-native systems, this integration has become essential for modern organizations, but it has also become more and more complex, especially as next-generation business systems depend on agile, flexible, interoperable, reliable, and secure cross-enterprise systems.
Reuse analysis of indirectly indexed arrays
Authors: Absar Javed , Catthoor Francky
Published: July 2006

We propose techniques for identifying and exploiting spatial and temporal reuse for indirectly indexed arrays. Indirectly indexed arrays are those arrays which are, typically, accessed inside multilevel loop nests and whose index expression includes not only loop iterators and constants but arrays as well. Existing techniques for improving locality are quite sophisticated in the case of directly indexed arrays. But, unfortunately, they are inadequate for handling indirectly indexed arrays. In this article we therefore extend the existing framework and techniques of directly indexed to indirectly indexed arrays. The concepts of reuse subspace, dependence vector, self, and group reuse are extended and applied in this new context. Also, lately scratch-pad memory has become an attractive alternative to data-cache, specially in the embedded multimedia community. This is because embedded systems are very sensitive to area and energy and the scratch-pad is smaller in area and consumes less energy on a per access basis compared to the cache of the same capacity. Several techniques have been proposed in the past for the efficient exploitation of the scratch-pad for directly indexed arrays. We extend these techniques by presenting a method for scratch-pad mapping of indirectly indexed arrays. This enables the scratch-pad to be used in a larger context than was possible before.
Handling inverted temperature dependence in static timing analysis
Authors: Dasdan Ali , Hom Ivan
Published: July 2006

In digital circuit design, it is typically assumed that cell delay increases with decreasing voltage and increasing temperature. This assumption is the basis of the cornering approach with cell libraries in static timing analysis (STA). However, this assumption breaks down at low supply voltages because cell delay can decrease with increasing temperature. This phenomenon is caused by a competition between mobility and threshold voltage to dominate cell delay. We refer to this phenomenon as the
inverted temperature dependence
(ITD). Due to ITD, it becomes very difficult to analytically determine the temperatures that maximize or minimize the delay of a cell or a path. As such, ITD has profound consequences for STA: (1) ITD essentially invalidates the approach of defining corners by independently varying voltage and temperature; (2) ITD makes it more difficult to find short paths, leading to difficulties in detecting hold time violations; and (3) the effect of ITD will worsen as supply voltages decrease and threshold voltage variations increase. This article analyzes the consequences of ITD in STA and proposes a proper handling of ITD in an industrial sign-off STA tool. To the best of our knowledge, this article is the first such work.
Computation and communication refinement for multiprocessor SoC design
Authors: Marculescu Radu , Ogras Umit Y. , Zamora Nicholas H.
Published: July 2006

Continuous advancements in semiconductor technology enable the design of complex systems-on-chips (SoCs) composed of tens or hundreds of IP cores. At the same time, the applications that need to run on such platforms have become increasingly complex and have tight power and performance requirements. Achieving a satisfactory design quality under these circumstances is only possible when both computation and communication refinement are performed efficiently, in an automated and synergistic manner. Consequently, formal and disciplined system-level design methodologies are in great demand for future multiprocessor design. This article provides a broad overview of some fundamental research issues and state-of-the-art solutions concerning both computation and communication aspects of system-level design. The methodology we advocate consists of developing abstract application and platform models, followed by application mapping onto the target platform, and then optimizing the overall system via performance analysis. In addition, a communication refinement step is critical for optimizing the communication infrastructure in this multiprocessor setup. Finally, simulation and prototyping can be used for accurate performance evaluation purposes.
Architecture description language (ADL)-driven software toolkit generation for architectural exploration of programmable SOCs
Authors: Mishra Prabhat , Shrivastava Aviral , Dutt Nikil
Published: July 2006

Advances in semiconductor technology permit increasingly complex applications to be realized using programmable systems-on-chips (SOCs). Furthermore, shrinking time-to-market demands, coupled with the need for product versioning through software modification of SOC platforms, have led to a significant increase in the software content of these SOCs. However, designer productivity is greatly hampered by the lack of automated software generation tools for the exploration and evaluation of different architectural configurations. Traditional hardware-software codesign flows do not support effective exploration and customization of the embedded processors used in programmable SOCs. The inherently application-specific nature of embedded processors and the stringent area, power, and performance constraints in embedded systems design critically require a fast and automated architecture exploration methodology. Architecture description language (ADL)-Driven design space exploration and software toolkit generation strategies present a viable solution to this problem, providing a systematic mechanism for a top-down design and validation of complex systems. The heart of this approach lies in the ability to automatically generate a software toolkit that includes an architecture-sensitive compiler, a cycle-accurate simulator, assembler, debugger, and verification/validation tools. This article illustrates a software toolkit generation methodology using the EXPRESSION ADL. Our exploration studies demonstrate the need for and usefulness of this approach, using as an example the problem of compiler-in-the-loop design space exploration of reduced instruction-set embedded processor architectures.
Can you see me now?
Authors: Benford Steve , Crabtree Andy , Flintham Martin , Drozd Adam , Anastasi Rob , Paxton Mark , Tandavanitj Nick , Adams Matt , Row-Farr Ju
Published: July 2006

We present a study of a mobile mixed reality game calledCan You See Me Now?in which online players are chased through a virtual model of a city by ‘runners’ (professional performers equipped with GPS and WiFi technologies) who have to run through the actual city streets in order to catch the players. We present an ethnographic study of the game as it toured through two different cities and draws upon video recordings of online players, runners, technical support crew, and also on system logs of text communication. Our study reveals the diverse ways in which online players experienced the uncertainties inherent in GPS and WiFi, including being mostly unaware of them, but sometimes seeing them as problems, or treating the as a designed feature of the game, and even occasionally exploiting them within gameplay. In contrast, the runners and technical crew were fully aware of these uncertainties and continually battled against them through an ongoing and distributed process of orchestration. As a result, we encourage designers to deal with such uncertainties as a fundamental characteristic of location-based experiences rather than treating them as exceptions or bugs that might be ironed out in the future. We argue that designers should explicitly consider four potential states of being of a mobile participant: connected and tracked, connected but not tracked, tracked but not connected, and neither connected nor tracked. We then introduce five strategies that might be used to deal with uncertainty in these different states for different kinds of participant: remove it, hide it, manage it, reveal it, and exploit it. Finally, we present proposals for new orchestration interfaces that reveal the ‘seams’ in the underlying technical infrastructure by visualizing the recent performance of GPS and WiFi and predicting the likely future performance of GPS.
The Standish report
Authors: Glass Robert L.
Published: July 2006

Reconsidering the relevancy of a frequently cited report on software project failures.
A machine-checked model for a Java-like language, virtual machine, and compiler
Authors: Klein Gerwin , Nipkow Tobias
Published: July 2006

We introduce Jinja, a Java-like programming language with a formal semantics designed to exhibit core features of the Java language architecture. Jinja is a compromise between the realism of the language and the tractability and clarity of its formal semantics. The following aspects are formalised: a big and a small step operational semantics for Jinja and a proof of their equivalence, a type system and a definite initialisation analysis, a type safety proof of the small step semantics, a virtual machine (JVM), its operational semantics and its type system, a type safety proof for the JVM; a bytecode verifier, that is, a data flow analyser for the JVM, a correctness proof of the bytecode verifier with respect to the type system, and a compiler and a proof that it preserves semantics and well-typedness. The emphasis of this work is not on particular language features but on providing a
unified
model of the source language, the virtual machine, and the compiler. The whole development has been carried out in the theorem prover Isabelle/HOL.
Modulation of Vascular Smooth Muscle Signaling by Reactive Oxygen Species
Authors: Lyle Alicia N. , Griendling Kathy K.
Published: July 2006

Modulation of signaling in vascular cells by reactive oxygen species (ROS) affects many aspects of cellular function, including growth, migration, and contraction. NADPH oxidases, important sources of ROS, regulate many growth-specific and migration-related signaling pathways. Identifying the precise intracellular targets of ROS enhances understanding of their role in cardiovascular physiology and pathophysiology.
Synaptic Plasticity In Vitro and In Silico: Insights into an Intracellular Signaling Maze
Authors: Ajay Sriram M. , Bhalla Upinder S.
Published: July 2006

Synaptic plasticity provides a record of neuronal activity and is a likely basis for memory. The early apparent simplicity of the process of synaptic plasticity has been lost in a flood of experimental data that now implicates some 200 signaling molecules in cellular memory. It is now clear that these signaling networks perform surprisingly sophisticated cellular decisions that weigh factors such as input patterns, location of stimulus, history of activity, and context. Computer models have followed experiments into this maze of molecular detail, often matching closely with their experimental counterparts, but perhaps losing simplicity in the process. Here, we suggest that the merger of models and experiment have begun to restore the earlier simplicity by outlining a few key functional roles for signaling networks in synaptic plasticity. In this review, we discuss the current state of understanding of synaptic plasticity in terms of models and experiments.
(De)constructing Mitochondria: What For?
Authors: Dimmer Kai S. , Scorrano Luca
Published: July 2006

Mitochondria are dynamic organelles, essential for cell life and death. The morphology of this organelle is determined by fusion and fission, controlled by a growing set of “mitochondria-shaping” proteins, which influence crucial signalling cascades, including apoptosis.