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121.
We report on a quantitative comparison between the single-source and the dual-interfering-source configurations for the detection of fluorescent heterogeneities embedded in a piecewise highly scattering homogeneous fluorescent background. The study is based on simulations with analytical solutions of the frequency-domain fluorescent diffuse photon density waves and practical signal-to-noise ratio considerations. Results show that dual-interfering sources outperform single-source techniques for the detection of heterogeneities in terms of fluorophore concentration and lifetime contrast. To detect the same inhomogeneity, less concentration and lifetime contrast is required with dual-interfering sources. 相似文献
122.
Miguel A. Martínez Javier Sanchis Xavier Blasco 《Engineering Applications of Artificial Intelligence》2006,19(8):927-938
Trends in controller design point to the integration of several objectives to achieve new performances. Moreover, it is easy to set the controller design problem as an optimization problem. Therefore, future improvements are likely to be based on the adequate formulation and resolution of the multiobjective optimization problem. The multiobjective optimization strategy called physical programming provides controller designers with a flexible tool to express design preferences with a ‘physical’ meaning. For each objective (settling time, overshoot, disturbance rejection, etc.) preferences are established through categories such as desirable, tolerable, unacceptable, etc. to which numerical values are assigned. The problem is normalized and converted to a single-objective optimization problem but normally it results in a multimodal problem very difficult to solve. Genetic algorithms provide an adequate solution to this type of problems and open new possibilities in controller design and tuning. 相似文献
123.
Ricardo Toledo Ramon Baldrich Xavier Orriols Juan Sanchez Xavier Binefa 《Multimedia Tools and Applications》2006,31(2):119-144
Advertising activities are one of the main aspects of companies. Its global evaluation is an important index, not only within economic sectors, but also for public economic policies. The evaluation of the adverts is carried out by specialised companies, which deliver advertisement expenditure information. Their work consist in an exhaustive collection of adverts (e.g., all adverts from any media), and deliver information (integrated from every media) relevant for their clients. The delivered information can range from statistical data to bear witness of an advertisement campaign. Important quality indicators for the delivered information are the exhaustiveness, the delay of delivering and a correct identification of different versions of an advert. In this article, we present an advanced computer-aided system for collecting and delivering advertising information from magazines and daily press. The system provides computer-aided data validation and exploitation resources. Using computerised document image analysis and image database indexing and retrieval, the system is able to locate an advert in a page, extract relevant quality indicators and search the advert (or similar ones) in a database. This tool is configured as an intranet and offers resources for image data acquisition, storage/retrieval and advert quality indicators extraction, however, the key of the system is the underlying idea of incorporating computer-aided visual information management.The EU has funded the system construction within the program: European Take-up of essential Information Society Technologies, Integrated Machine Vision (EUTIST-IMV), task CV-AdControl. . 相似文献
124.
Intrinsic Statistics on Riemannian Manifolds: Basic Tools for Geometric Measurements 总被引:2,自引:0,他引:2
Xavier Pennec 《Journal of Mathematical Imaging and Vision》2006,25(1):127-154
In medical image analysis and high level computer vision, there is an intensive use of geometric features like orientations,
lines, and geometric transformations ranging from simple ones (orientations, lines, rigid body or affine transformations,
etc.) to very complex ones like curves, surfaces, or general diffeomorphic transformations. The measurement of such geometric
primitives is generally noisy in real applications and we need to use statistics either to reduce the uncertainty (estimation),
to compare observations, or to test hypotheses. Unfortunately, even simple geometric primitives often belong to manifolds
that are not vector spaces. In previous works [1, 2], we investigated invariance requirements to build some statistical tools
on transformation groups and homogeneous manifolds that avoids paradoxes. In this paper, we consider finite dimensional manifolds
with a Riemannian metric as the basic structure. Based on this metric, we develop the notions of mean value and covariance
matrix of a random element, normal law, Mahalanobis distance and χ2 law. We provide a new proof of the characterization of Riemannian centers of mass and an original gradient descent algorithm
to efficiently compute them. The notion of Normal law we propose is based on the maximization of the entropy knowing the mean
and covariance of the distribution. The resulting family of pdfs spans the whole range from uniform (on compact manifolds)
to the point mass distribution. Moreover, we were able to provide tractable approximations (with their limits) for small variances
which show that we can effectively implement and work with these definitions. 相似文献
125.
Soft errors are an important challenge in contemporary microprocessors. Particle hits on the components of a processor are expected to create an increasing number of transient errors with each new microprocessor generation. In this paper we propose simple mechanisms that effectively reduce the vulnerability to soft errors In a processor. Our designs are generally motivated by the fact that many of the produced and consumed values in the processors are narrow and their upper order bits are meaningless. Soft errors canted by any particle strike to these higher order bits can be avoided by simply identifying these narrow values. Alternatively soft errors can be detected or corrected on the narrow values by replicating the vulnerable portion of the value inside the storage space provided for the upper order bits of these operands. We offer a variety of schemes that make use of narrow values and analyze their efficiency in reducing soft error vulnerability of level-1 data cache of the processor 相似文献
126.
Volume-Surface Trees 总被引:2,自引:0,他引:2
Tamy Boubekeur Wolfgang Heidrich Xavier Granier Christophe Schlick 《Computer Graphics Forum》2006,25(3):399-406
Many algorithms in computer graphics improve their efficiency by using Hierarchical Space Subdivision Schemes (HS3), such as octrees, kD‐trees or BSP trees. Such HS3 usually provide an axis‐aligned subdivision of the 3D space embedding a scene or an object. However, the purely volume‐based behavior of these schemes often leads to strongly imbalanced surface clustering. In this article, we introduce the VS‐Tree, an alternative HS3 providing efficient and accurate surface‐based hierarchical clustering via a combination of a global 3D decomposition at coarse subdivision levels, and a local 2D decomposition at fine levels near the surface. First, we show how to efficiently construct VS‐Trees over meshes and point‐based surfaces, and analyze the improvement it offers for cluster‐based surface simplification methods. Then we propose a new surface reconstruction algorithm based on the volume‐surface classification of the VS‐Tree. This new algorithm is faster than state‐of‐the‐art reconstruction methods and provides a final semi‐regular mesh comparable to the output of remeshing algorithms. 相似文献
127.
The paper investigates the control of oscillating modes occurring in open-channels, due to the reflection of propagating waves on the boundaries. These modes are well represented by linearized Saint-Venant equations, a set of hyperbolic partial differential equations which describe the dynamics of one-dimensional open-channel flow around a given stationary regime. We use a distributed transfer function approach to compute a dynamic boundary controller that cancels the oscillating modes over all the canal pool. This result is recovered with a Riemann invariants approach in the case of a frictionless horizontal canal pool. The effect of a proportional boundary control on the poles of the transfer matrix is then characterized by a root locus, and we derive an asymptotic result for high frequencies closed-loop poles. 相似文献
128.
Tordoff Michael G.; Grijalva Carlos V.; Novin Donald; Butcher Larry L.; Walsh John H.; Pi-Sunyer F. Xavier; VanderWeele Dennis A. 《Canadian Metallurgical Quarterly》1984,98(6):1039
Two experiments with male Long-Evans rats examined sympathetic involvement in the lateral hypothalamic (LH) lesion syndrome. Ss were surgically or chemically sympathectomized and then given LH lesions. At 24 hrs postlesion, lesion-induced hyperglycemia but not hyperthermia was attenuated by splanchnicectomy and celiac ganglionectomy. Hyperthermia but not hyperglycemia was attenuated by adrenal demedullation, adrenalectomy, and daily neonatal guanethidine (50 mg/kg) treatment. Guanethidine-sympathectomized Ss also displayed lower basal temperatures, more perilesion chromatolysis, and more severe external symptoms than controls. No form of sympathectomy affected lesion-induced gastric pathology, plasma gastrin concentrations, or body weight loss, nor did any sympathectomy influence the recovery of ingestive behavior, daily food intake, the feeding response to 2-deoxy-dextro-glucose, or body weight maintenance in recovered LH-lesioned Ss. Results suggest that sympathetic hyperactivity contributed to some aspects of the acute LH syndrome: Hyperglycemia resulted from sympathetic outflow to the abdomen, whereas hyperthermia was determined by circulating catecholamines and extra-abdominal sympathetic innervation. Findings fail to support the hypothesis that chronic increases in sympathetic tone are responsible for the reduced food intake and body weight of the LH-lesioned Ss. (47 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
129.
130.
A suite of FORTRAN subroutines/functions to generate data using empirical formulas for physical sputtering of mono-atomic targets for any elemental incident ion (atom), chemical erosion of graphite, Radiation Enhanced Sublimation (RES) of graphite, the number and energy backscattering coefficients for any elemental incident ion (atom) on a compound target and thermal evaporation of graphite is presented. Since chemical erosion, RES and thermal evaporation depend on the surface temperature of graphite, a subroutine implementing the 1-D heat diffusion equation to determine the temperature of any plasma-facing graphite surface is implemented. As an example to illustrate the use of these subroutines/functions, a simple model for the erosion of a plasma-facing surface, consisting of a simple collisionless sheath model, a 1-dimensional steady state heat diffusion model and 0-dimensional steady state particle balance at the target is developed and a sample listing of the program is presented.