253,440 research outputs found
A Geometric Algebra Co-Processor for Color Edge Detection
No full textThis paper describes advancement in color edge detection, using a dedicated Geometric Algebra (GA) co-processor implemented on an Application Specific Integrated Circuit (ASIC). GA provides a rich set of geometric operations, giving the advantage that many signal and image processing operations become straightforward and the algorithms intuitive to design. The use of GA allows images to be represented with the three R, G, B color channels defined as a single entity, rather than separate quantities. A novel custom ASIC is proposed and fabricated that directly targets GA operations and results in significant performance improvement for color edge detection. Use of the hardware described in this paper also shows that the convolution operation with the rotor masks within GA belongs to a class of linear vector filters and can be applied to image or speech signals. The contribution of the proposed approach has been demonstrated by implementing three different types of edge detection schemes on the proposed hardware. The overall performance gains using the proposed GA Co-Processor over existing software approaches are more than 3.2× faster than GAIGEN and more than 2800× faster than GABLE. The performance of the fabricated GA co-processor is approximately an order of magnitude faster than previously published results for hardware implementations
Edge detection filter based on Mumford-Shah green function
No full textIn this paper, we propose an edge detection algorithm based on the Green function associated with Mumford-Shah (M-S) segmentation model. This Green function has a singularity at its center. A regularization method is therefore proposed here to obtain an edge detection filter known here as Bessel filter. This filter is robust in the presence of noise and its implementation is simple. It is demonstrated here that this filter detects edges particularly in the case of curved boundaries and sharp corners, more accurately than popular filters in the recent literature. A mathematical argument is also provided to prove that the gradient magnitude of the convolved image with this filter has local maxima in discontinuities of the original image. The Bessel filter enjoys better overall performance (the product of the detection performance and localization indices) in Canny-like criteria than the state of art filters in the literature. Quantitative and qualitative evaluations of the edge detection algorithms investigated in this paper on synthetic and real world benchmark images confirm the theoretical results presented here, indicating the superiority of the Bessel filter over the popular edge detection filters. The numerical complexity of the algorithm proposed here is as low as any convolution-based edge detection algorithm
The relationship between the (VO2)-O-. Slow component, muscle metabolites and performance during very-heavy exhaustive exercise
No full textThis study examined the relationship between the V O(2) response, particularly the slow component (SC), muscle metabolite changes and performance during very-heavy exhaustive exercise. Sixteen active females performed a graded exercise test to determine V O(2peak) and the lactate threshold followed 48h later by a constant-load cycle test to exhaustion (ET) at 85% V O(2peak) intensity. Muscle biopsies and capillary blood samples were obtained before and after the ET to determine changes in muscle ATP, pH, lactate and phosphocreatine and also plasma pH and lactate. Breath-by-breath data from the ET were smoothed using 5-s averages and fit to a three-component exponential model. The mean time to exhaustion (t(exh)) during the ET was 16.8 (+/-6.4) min. Results showed no correlation between the SC and t(exh) or any muscle metabolite changes (p>0.05). Significant correlations (p<0.05) were evident between t(exh) and tau; tau(0) (r=-0.54), tau(1) (r=-0.65), change in (Delta) pH(b) (r=-0.60), Delta[La(-)](b) (r=-0.58) and [La(-)](b post) (r=-0.64). Significant correlations (p<0.05) were also evident between tau(1) and [La(-)](b post) (r=0.54). Furthermore, a negative value resulted when the accumulated oxygen deficit was calculated for the entire duration of the ET. Results showed no association between the amplitude of the SC and t(ext) or to changes in muscle/blood metabolites, suggesting that the SC is not a determinant of high-intensity exercise tolerance. Furthermore, it is possible that a reduced perturbation of anaerobic energy sources, as a result of a faster tau(1), may have contributed to a longer t(exh)
Edge detection by landing honeybees: behavioural analysis and model simulations of the underlying mechanism
Get PDFKern R, Egelhaaf M, Srinivasan MV. Edge detection by landing honeybees: behavioural analysis and model simulations of the underlying mechanism. Vision Research. 1997;37(15):2103-2117
Financial Constraints: Routine Versus Cutting Edge R&D Investment
Get PDFWe analyze financial constraints for R&D, where we account for heterogeneity among investments which has been neglected in previous literature. According to economic theory, investments should be distinguished by their degree of uncertainty, e.g. routine R&D versus cutting-edge R&D. Financial constraints should be more binding for cutting-edge R&D than for routine R&D. Using panel data we find that R&D spending of firms devoting a significant fraction of R&D to cutting-edge projects is curtailed by credit constraints while routine R&D investments are not. This has important policy implications with respect to the distribution of R&D subsidies in the economy. --R&D,Financial Constraints,Panel Data
Direct numerical simulation of turbulent flow past a trailing edge and the associated noise generation
No full textDirect numerical simulations (DNS) are conducted of turbulent flow passing an infinitely thin trailing edge (TE). The objective is to investigate the turbulent flow field in the vicinity of the TE and the associated broadband noise generation. To generate a turbulent boundary layer a short distance from the inflow boundary, high amplitude lifted streaks and disturbances that can be associated with coherent outer layer vortices are introduced at the inflow boundary. A rapid increase in skin friction and a decrease in boundary layer thickness and pressure fluctuations is observed at the trailing edge. It is demonstrated that the behaviour of the hydrodynamic field in the vicinity of the TE can be predicted with reasonable accuracy using triple deck theory if the eddy viscosity is accounted for. Point spectra of surface pressure difference are shown to vary considerably towards the trailing edge, with a significant reduction of amplitude occurring in the low frequency range.The acoustic pressure obtained from the DNS is compared with predictions from two- and three-dimensional acoustic analogies and the classical trailing edge theory of Amiet. For low frequencies, two dimensional theory succeeds in predicting the acoustic pressure in the far field with reasonable accuracy due to a significant spanwise coherence of the surface pressure difference and predominantly two dimensional sound radiation. For higher frequencies, however, the full three dimensional theory is required for an accurate prediction of the acoustic far field. DNS data are used to test some of the key assumptions invoked by Amiet for the derivation of the classical trailing edge theory. Even though most of the approximations are shown to be reasonable, they collectively lead to a deviation from the DNS results, in particular for higher frequencies. Moreover, because the three dimensional acoustic analogy does not provide significantly improved results, it is suggested that some of the discrepancies can be attributed to the approach of evaluating the far field sound using a Kirchhoff-type integration of the surface pressure difference
Calculation of inducted currents using edge elements and T-T0 formulation
No full textThe paper discusses methods of calculating induced currents in multiply connected regions containing solid conductors. In particular, the formulation based on edge elements using the electric vector potential has been considered. The equations are explained using the language of circuit theory. It is observed that the edge values of T0 represent the loop currents in the loops surrounding the ‘holes’. It is also shown that the iterative solution may be accelerated by over specifying the number of loop currents in the loops around the ‘holes’
Three-dimensional edge waves in plates
No full textThis paper describes the propagation of three-dimensional symmetric waves localized near the traction-free edge of a semi-infinite elastic plate with either traction-free or fixed faces. For both types of boundary conditions, we present a variational proof of the existence of the low-order edge waves. In addition, for a plate with traction-free faces and zero Poisson ratio, the fundamental edge wave is described by a simple explicit formula, and the first-order edge wave is proved to exist. Qualitative variational predictions are compared with numerical results, which are obtained using expansions in three-dimensional Rayleigh–Lamb and shear modes. It is also demonstrated numerically that for any non-zero Poisson ratio in a plate with traction-free faces, the eigenfrequencies related to the first-order wave are complex valued
Grouping puts figure-ground assignment in context by constraining propagation of edge assignment.
Get PDFFigure-ground organization involves the assignment of edges to a figural shape on one or the other side of each dividing edge. Established visual cues for edge assignment primarily concern relatively local rather than contextual factors. In the present article, we show that an assignment for a locally unbiased edge can be affected by an assignment of a remote contextual edge that has its own locally biased assignment. We find that such propagation of edge assignment from the biased remote context occurs only when the biased and unbiased edges are grouped. This new principle, whereby grouping constrains the propagation of figural edge assignment, emerges from both subjective reports and an objective short-term edge-matching task. It generalizes from moving displays involving grouping by common fate and collinearity, to static displays with grouping by similarity of edge-contrast polarity, or apparent occlusion. Our results identify a new contextual influence on edge assignment. They also identify a new mechanistic relation between grouping and figure-ground processes, whereby grouping between remote elements can constrain the propagation of edge assignment between those elements. Supplemental materials for this article may be downloaded from http://app.psychonomic-journals.org/content/supplemental
Effects of high-intensity interval training on the VO2 response during severe exercise
No full textThis study examined the effect of high-intensity interval training on the VO2 response during severe, constant-load exercise. Prior to, and following training, 10 females (V O2 peak 37.4+/-6.0 mL kg-1 min-1) performed a graded exercise test to determine VO2 peak and lactate threshold (LT) and a 6 min cycle test (CT) at the pre-training VO2 peak intensity. Training involved high-intensity intervals (2 min work, 1 min rest) performed 3x week for 8 weeks. Breath-by-breath data from 0 to 6 min during the CT were smoothed using 5s averages and fit to a bi-exponential model starting from 20s. Training resulted in significant improvements in VO2 max (2.34+/-0.37-2.78+/-0.30 L min-1), power at VO2 max (170+/-26-204+/-25 W) and power at LT (113+/-17-136+/-20 W) (p0.05) in the time constants of either phase or the amplitude of the slow component (318+/-67-380+/-48 mL; p=0.15). In conjunction, accumulated oxygen deficit (AOD) (43.7+/-9.8-17.2+/-2.8 mL O2 eq kg-1) and anaerobic contribution to the CT (19.4+/-4.4-7.2+/-1.2\%) were significantly reduced. In contrast to previous moderate-intensity research, a high-intensity interval training program increased A1 and VO2 EE for the same absolute exercise intensity, decreasing the AOD during a severe-intensity CT
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