Unwanted Edge Research Articles

Normalizing Basis Functions: Approximate Stationary Models for Large Spatial Data

ABSTRACTIn geostatistics, traditional spatial models often rely on the Gaussian process (GP) to fit stationary covariances to data. It is well known that this approach becomes computationally infeasible when dealing with large data volumes, necessitating the use of approximate methods. A powerful class of methods approximate the GP as a sum of basis functions with random coefficients. Although this technique offers computational efficiency, it does not inherently guarantee a stationary covariance. To mitigate this issue, the basis functions can be ‘normalized’ to maintain a constant marginal variance, avoiding unwanted artefacts and edge effects. This allows for the fitting of nearly stationary models to large, potentially non‐stationary datasets, providing a rigorous base to extend to more complex problems. Unfortunately, the process of normalizing these basis functions is computationally demanding. To address this, we introduce two fast and accurate algorithms to the normalization step, allowing for efficient prediction on fine grids. The practical value of these algorithms is showcased in the context of a spatial analysis on a large dataset, where significant computational speedups are achieved. While implementation and testing are done specifically within the LatticeKrig framework, these algorithms can be adapted to other basis function methods operating on regular grids.

An Approach for the Reduction of Unwanted Edges in Contour Detection Based on Local Filtering

In this paper, an approach for the reduction of unwanted edges in contour detection based on local filtering is presented. Our approach can be used as a preprocessing step before contour detection. Also our approach is useful for object recognition based on feature extraction tasks, because many contour detection methods can’t delete all unwanted edges carefully. Our method consists of a computational algorithm that has 7 steps. Including smoothing, edge detection, smoothing, decreasing of pixels, thresholding, local filtering, and mask creation respectively. We use smoothing for adhering neighbor edge pixels and weakening alone edge pixels. So we can amplify the correct edge pixels and attenuate unwanted edge pixels by smoothing the edge image. In local filtering, we use a proposed casual template that determines noisy regions and correct regions and therefore can create a mask matrix that its elements related to mentioned regions. Finally we can use the "mask matrix" for improving contours by using a “And” operator and we ensure final contour that has a few context effect.

Smoothing of inter-layer edge artifacts in depth-map computer-generated holograms.

In the depth-map computer-generated hologram (CGH), inter-layer edge artifacts are observed in the discontinuous edges of section-wise depth-map objects. CGH synthesis, utilizing the hybrid smoothing method of silhouette masking and edge-apodization, alleviates unwanted inter-layer edge artifacts. The proposed method achieves improved de-artifact filtering that generates holographic images closer to the ground truth image of the depth-map object unattainable by the conventional CGH synthesis method.

Classical-to-topological transmission line couplers

Recent advances in topologically robust waveguiding for electromagnetic systems have presented opportunities for improving practical photonic and microwave devices. To bring this rich area of physics within the reach of application, it is critical for such systems to be interfaced with classical, continuous waveguiding, and transmission line technology. This Letter presents a compact, highly efficient transition from a classical metallic transmission line to a topologically nontrivial line wave emulating the quantum spin Hall effect. A zero-gap antipodal slot line is used as the starting transmission line, which is then coupled to the topological metasurface via a field matching procedure. Additional modifications to the interface between the two structures to eliminate unwanted edge coupling improve transmission further. A simulated loss analysis isolates the effect of the transitions from the rest of the structure, showing a loss contribution of only 2.1% per classical-to-topological conversion. Using the transition, a quantitative characterization of the robustness of common topologically protected devices is presented. This design lays the foundation to integrate topologically robust metasurface transmission lines to traditional systems, opening the door to future uses of such structures in systems.

WITHDRAWN: Development and optimization of cold rolled slitting machine process

Slitting machine is universally handled for trimming the unwanted edge part of broad sheet metal stock. A problem of camber formation at the time of cutting is quite common in cold rolling slitting machine. When the strip passes through skin pass operation, burr is formed due to friction which will result in bad surface finish and also when thrust force do not match with the pulling force results into camber covering edges of strips. The study focuses on the effects of cutting boundaries on specific strengths such as shear strength and thin line profile. Advancement in the cutting parameter is incorporated to eliminate the camber formation during the slitting operation. The study focuses on the effects of cutting boundaries on specific strengths such as shear strength and thin line profile. The scarp winding mechanism is developed considering the ergonomics of the workplace. The carrying of cutter discs consequently is found to be terribly little in comparison thereupon existing slitting methodology. Optimization of slitting process line is done by using Taguchi Method. Moreover, the paper provides a detailed CAD modeling and optimization for slitting operation which will enhance the operational parameters of the slitting machine.

SAR Image Edge Detection Robust to Isolated Strong Scatterers Using Anisotropic Morphological Directional Ratio Test

Edge detection via anisotropic average directional ratio (AADR) for synthetic aperture radar (SAR) images produces unwanted and fragmentized edge pixels due to the speckle noise and sporadic highlight pixels from isolated strong scatterers in real scenes. In this paper, a novel robust edge detector is developed for SAR images. Anisotropic morphological directional ratio (AMDR) is proposed to describe the intensity variation in SAR images by combining rotated biwindows and the weighted median filter (WMF). Then, multiplicative spatial and directional matched filters are presented to improve edge localization and direction estimation of the AMDR. Based on the enhanced AMDR, the edge strength map (ESM) and the edge direction map (EDM) are embedded into the route of Canny detector to extract thin edges. Moreover, an edge remedy processing is given to improve the connectivity of edges near junctions. Finally, performance comparison is conducted with the existing AADR-based detectors on synthetic and real SAR images using the receiver-operating-characteristic (ROC) curves, which shows that the proposed AMDR-based detector possesses evidently more robust ability to counteract sporadic isolated highlight pixels in SAR images than the existing AADR-based detectors do. Moreover, in the case without sporadic isolated highlight pixels, its performance is also comparable with those of existing competitive AADR-based ones.

Combining sparse representation and local rank constraint for single image super resolution

Sparse representation based reconstruction methods are efficient for single image super resolution. They generally consist of the code stage and the linear combination stage. However, the simple linear combination has not considered the image edge constraint information of image, and hence the classical sparse representation based methods reconstruct the image with the unwanted edge artifacts and the unsharp edges. In this paper, considering that the local rank is able to extract better edge information than other edge operator, we propose a new single image super resolution method by combining the sparse representation and the local rank constraint information. In our method, we first learn the local rank of the HR image via the traditional sparse representation model, and then use it as the edge constraint to restrict the image edges during the linear combination stage to reconstruct the HR image. Furthermore, we propose a nonlocal and global optimization model to further improve the HR image quality. Compared with many state-of-art methods, extensive experimental results validate that the proposed method can obtain the less edge artifacts and sharper edges.

Wear on overlay welded HCWI vs. quenched and tempered low alloyed carbon steels evaluated with granite in a laboratory drum test machine

This present test evaluates wear resistance of overlay welded High Chromium White Iron (HCWI) in comparison with quenched and tempered low alloyed carbon steels within a hardness range between 400 and 700HBW. The HCWI overlay material had a carbon content in the range of 3–5% and a chromium content of 20–25%. The wear performance was evaluated by the use of two different sizes of granite rocks. This test was undertaken in a laboratory drum machine, which aimed to resemble typical conditions expected within raw material flows in mines and quarries. The secondary aim of the investigation was to further evaluate the material selection process by comparing ore, residuals and aggregates from real-world mining sites with the respective wear resistant materials being employed. The drum machine used had a diameter of 800mm and a width of 100mm. The drum rotated on a horizontal axle, which lifted the aggregate to a certain height, thus creating a sliding motion. Each test evaluated 34 samples, attached at the inner side of the drum shell. The samples were installed inside a depressed holder to protect against unwanted edge wear. The holders were specifically designed to fit hard materials such as HCWI. The HCWI overlay material was ground flat at the top and cracks were sealed with epoxy. The experimental results demonstrated how different size of abrasives resulted in significantly different wear responses on the tested materials and that the developed test method can provide valuable information in the selection of wear resistant material.

AN INNOVATIVE MORPHOLOGICAL APPROACH FOR NOISE REMOVAL CUM EDGE DETECTION FOR DIGITIZED PAINTINGS

The older paintings suffer from breaks in the substrate, the paint, or the varnish. When we digitized these paintings, they can be modified using mathematical algorithms and cracks are eliminated so as to maintain the quality. The field of computer vision is concerned with extracting features and information from images in order to make analysis of images easier, so that more and more information can be extracted. The primary goal of this study is to use novel approach for noise removal cum unwanted edge from digitized paintings. The method used for both noise removal and edge detection is mathematical morphology. On the basis of set theory, mathematical morphology is used for image processing, analyzing and comprehending. It is a powerful tool in the geometric morphological analysis and description. The results exhibit that the new method overcomes the deficiency of conventional methods and efficiently removes the noise and detects the edges for digitized paintings.

A new efficient method for topographic distortion correction, analytical continuation, vertical derivatives and using equivalent source technique: Application to field data

In general, potential field data are noisy due to the surveys in rugged topography. Standard reduction techniques are not fully adequate to eliminate this problem. Most of the interpretation techniques require the observations measured on the horizontal surface. Furthermore, upward and downward continuations, and vertical derivatives can improve the ambiguity in the potential field data. In present, there are methods for the application of the analytical continuations and derivatives, but these are not successful enough due to technical restrictions and unwanted edge effects. In this paper, an easy and efficient technique known as the equivalent source is applied to the observations made over the rugged topography. The presented method is tested on synthetic example using an anomaly of a sphere located below the synthetic topography. At first, our method is applied only to obtain a topographic distortion corrected map by moving forward windowed parts of the area. Afterwards, analytic continuations of the topographic distortion corrected map are obtained. Finally, a vertical derivative map is obtained from the analytic continuations of the topographic distortion corrected map. Amplitudes are controlled along profiles on top of theoretical and calculated spheres. A good correlation can be observed from the amplitude values. This method is also applied to the field data. The second vertical derivative map is produced from the topographic distortion corrected and 5 km upward continued gravity map of the region. We note that by the interpretations identified faults in these map are in good agreement with the faults shown in the structural map of the region.

Interactive focus maps using least-squares optimization

We present a new algorithm that enlarges a focus region in a given network map without removing non-focus (i.e., context) network parts from the map or changing the map’s size. In cartography, this problem is usually tackled with fish-eye projections, which, however, introduce severe distortion. Our new algorithm minimizes distortion and, with respect to this objective, produces results of similar quality compared to an existing algorithm. In contrast to the existing algorithm, the new algorithm achieves real-time performance that allows its application in interactive systems. We target applications where a user sets a focus by brushing parts of the network or the focus region is defined as the neighborhood of a moving user.A crucial feature of the algorithm is its capability of avoiding unwanted edge crossings. Basically, we first solve a least-squares optimization problem without constraints for avoiding edge crossings. The solution we find is then used to identify a small set of constraints needed for a crossing-free solution and, beyond this, allows us to start an animation enlarging the focus region before the final, crossing-free solution is found. Moreover, memorizing the non-crossing constraints from an initial run of the algorithm allows us to achieve a better runtime on any further run – assuming that the focus region does not move too much between two consecutive runs. As we show with experiments on real-world data, this enables response times well below 1 second.

The removal of unwanted edge contours from gravity datasets

Gravity data is widely used in the search for mineral deposits, and can be collected using ground, borehole, airborne, shipborne and satellite platforms. The boundaries between rocks with differing densities result in boundaries in their corresponding gravity anomalies. These boundaries, or edges, can be located using techniques based on horizontal derivatives of the data. Edge contours that do not relate to the current interpretation project can be considered as noise, and high resolution data can possess a proliferation of such edges, making interpretation difficult. While smoothing can be applied to reduce the number of edges, it has the disadvantage that the remaining edge locations are shifted and the shape of the edge contours is altered. Three methods are discussed here for the removal of unwanted edge contours. The first method removes edges which are not present in the data after its upward continuation to a user-selected height. The second method removes edges whose amplitude is below a given threshold, and the final method removes the smallest edge contours.

Implementation of edge-preserving regularization for frequency-domain diffuse optical tomography

In this study, we first propose the use of edge-preserving regularization in optimizing an ill-conditioned problem in the reconstruction procedure for diffuse optical tomography to prevent unwanted edge smoothing, which usually degrades the attributes of images for distinguishing tumors from background tissues when using Tikhonov regularization. In the edge-preserving regularization method presented here, a potential function with edge-preserving properties is introduced as a regularized term in an objective function. With the minimization of this proposed objective function, an iterative method to solve this optimization problem is presented in which half-quadratic regularization is introduced to simplify the minimization task. Both numerical and experimental data are employed to justify the proposed technique. The reconstruction results indicate that edge-preserving regularization provides a superior performance over Tikhonov regularization.

Band optimization of two-dimensional photonic crystal surface-emitting laser

The three-dimensional (3D) plane wave expansion method with supercell approximationhas been employed to investigate in detail the band structure of the two-dimensionalphotonic crystal (PhC) surface-emitting laser with square lattice. The symmetricpoint band structure has been calculated to obtain the optimized structures ofPhC surface-emitting lasers. There exists a range of parameter pairs, includingperiods and area-filling factors of the PhC, which can create an in-plane stopband at the high frequency side of the monopole mode at the second order of theΓ-point(Γ2- 1) in each structure. This in-plane stop band isolatesΓ2- 1 from the unwanted band edge modes, inhibits the spontaneous emission at the high frequency sideof Γ2- 1, makes the device achieve single band edge mode lasing oscillation and improves theperformance of the PhC surface-emitting laser. The resonant spectra, quality factors andoutput efficiencies have been calculated by the 3D finite-difference time-domain method toverify the band optimization, which provides important guidelines for device design andfabrication.

Comparative evaluation of motor unit architecture models

We present a statistical evaluation and comparison of the simulation outcomes of nine different motor unit architecture modeling approaches, which derive from combinations of four motor unit territory placement algorithms with two innervation pattern algorithms (one of the combinations allows for a double approach). We test how well the outcomes of these models agree with well-established physiological principles. Our results show that algorithms based on independent and uniformly distributed territory placement always lead to an unwanted edge effect consisting in a decay of the number of overlapping motor unit territories toward the edge of the muscle cross section. This edge effect interferes with the properties of the simulated motor units. On the other hand, controlled placement of motor units, so as to minimize the spatial variance of muscle fiber density (MFD), can result in simulated motor units which better reflect the empirical evidence currently available about motor unit architecture.

Suppression of edge cracking in layered ceramic composites by edge coating

A strategy is proposed to reduce surface tensile stresses that develop in ceramic microlaminate structures. As a specific example, surface stresses, which can lead to unwanted edge cracking, appear within a thin alumina/mullite layer bounded by thicker alumina layers after fabrication at some elevated temperature and subsequent cooling. A stress analysis is performed using the finite element method on a geometry in which the (edge) surface of the ceramic sandwich structure has been coated with an overlayer of the alumina/mullite material with thickness proportional to the initial buried layer thickness. These analyses show there is a critical thickness of the overlayer at which the surface tensile stresses can be reduced to zero. Stress concentration factors are calculated numerically for cracks propagating through this structure, and thus the resistance to surface cracking is quantified.

Computer modeling of in terferograms of flowing plasma and determination of the phase shift

Interferograms of the flowing gas contain information about the phase shift between the object and the reference beams. The determination of the phase shift is the first step in getting information about the inner distribution of the density in cylindrically symmetric discharges. Slightly modified Takeda method based on the Fourier transformation is applied to determine the phase information from the interferogram. The least squares spline approximation is used for approximation and smoothing intensity profiles. At the same time, cubic splines with their end-knots conditions naturally realize “hanning windows” eliminating unwanted edge effects. For the purpose of numerical testing of the method, we developed a code that for a density given in advance reconstructs the corresponding interferogram.

An Incident-Beam Monitor for Use in Protein Crystallography at a Synchrotron Source

A compact incident-beam monitor has been developed for use in synchrotron protein crystallography at the National Synchrotron Light Source beamline X8C. Incident-beam intensity is monitored by measurement of the radiation scattered from a thin polymer film into a PIN diode. For improved statistical accuracy, the scattering film can be replaced by a thin metal foil. Fluorescent radiation emitted by the metal foil increases the beam-monitoring signal up to 50 times relative to that produced by scattering alone. With this design, the forward-scattered radiation is restricted to an area not larger than the beam stop, minimizing excessive background radiation. Support materials have been optimized so that no unwanted edge effects are present between 6 and 19.5 keV, making the detector useful for monitoring incident-beam intensities over the wide range of absorption edges often associated with multiwavelength anomalous diffraction (MAD) experiments. Accurate incident-beam monitoring also simplifies optimization of the X-ray beam through the diffractometer collimation after each new electron orbit is established in the synchrotron.

Aperture tapering in a coherent optical correlator

Sharp edges located in an optical correlator input beam cause unwanted edge effects. A 1-D analysis is used to demonstrate this effect and how edge tapers can reduce this effect. Then an aperture made on film approximating the best taper is used to reduce the spurious signals in a matched filter correlator.