Stochastic simulation and analysis of the operation of computing systems with structural redundancy

One way to increase the reliable and robust operation of large-scale computing systems is to introduce a reserve (a structural redundancy system) to them. A model for the analysis of the operation of distributed computing systems is proposed. The results of analytical and simulation modeling are presented. Flows of events with a Weibull distribution (shape parameter values of 1 and 0.78) are considered..     

Using the model of a mixture of a uniform distribution and a von Mises distribution for segmentation of anisotropic images

An algorithm is proposed for segmenting anisotropic image based on estimates of the local orientation of textures obtained using a gradient structural tensor. A mixture of a uniform distribution and a von Mises distribution is used as the estimate model. An estimation algorithm for the unknown parameters of the mixture based on trigonometric moments is obtained. Examples are given demonstrating the effectiveness of the segmentation algorithm in identifying textures with one dominant direction.     

针对不均匀光照高反光 注塑工件图像的缺陷定位和分割

光照不均匀的现象在高反光注塑工件检测过程中十分常见,对于缺陷的定位和提取造成了很大影响.为了解决注塑工件图像中普遍存在的光照不均匀问题,提高缺陷提取的成功率,提出了一种基于行像素灰度校正的不均匀光照图像增强算法,使用二次定位的阈值图像分割方法对柱状注塑工件进行了缺陷定位和分割.建立新的行像素灰度校正系数模型,对图像的每...     

Generalized expressions of second and third order for the evaluation of standard measurement uncertainty

The Guide to the Expression of Uncertainty in Measurement (GUM) requires the use of a first-order Taylor series expansion for propagating uncertainties. However, when the measurement function is strongly non-linear the use of this linear approximation may be inadequate and therefore higher order terms from the Taylor series cannot be neglected. The present paper aims to derive generalized expressions of second and third order for the evaluation of the estimate of a measurand and its associated standard uncertainty. A case study is given to illustrate an application of the proposed methods and the results obtained with the GUM method are compared to the corresponding ones when applying the method proposed in GUM Supplement 1.     

Estimating the efficiency of two algorithms for segmentation of digital radiation images of test objects

A mathematical model that describes digital radiation images of test objects is presented. Two algorithms are given for automatic segmentation of digital images distorted by additive noises. The efficiency of the algorithms is estimated based on mathematical modeling.     

Segmentation and tracking of live cells in phase-contrast images using directional gradient vector flow for snakes

Cell shape is an important characteristic of the physiological state of a cell and is used as a primary read-out of cell behaviour in various assays. Automated accurate segmentation of cells in microscopy images is hence of large practical importance in cell biology. We report a simple algorithm for automated cell segmentation in high-magnification phase-contrast images, which takes advantage of the characteristic directionality of the local image intensity gradient at cellular boundaries due to the 'halo-effect'. We employ a two-step algorithm in which a gradient vector flow (GVF) field is first used to direct active contours to an approximate cell boundary. A directional GVF (DGVF) field is then calculated by considering only edges for which the image intensity gradient is directed outwards with respect to the approximate cell contour. Subsequently, the DGVF field is used to refine the cell contour, by directing active contours to edges with the desired gradient directionality. This method allows us to accurately segment cells in an image series, as well as follow the dynamics of cell shape over time in an automated fashion.     

Comparison of structural and hemostatic properties of the poly-N-acetyl glucosamine Syvek Patch with products containing chitosan

Polysaccharides are becoming increasingly developed as therapeutics and medical products, as the new field of Glycomics expands. Glycosaminoglycans that contain N-acetyl glucosamine constituents have been the focus of research leading to medical devices. A new hemostatic bandage, the Syvek Patch, has been introduced in the recent past for the control of bleeding at vascular access sites in interventional cardiology and radiology procedures. This product consists of poly-N-acetyl glucosamine (pGlcNAc) isolated in a unique fiber crystalline structural form from the large-scale culture and processing of a marine diatom. The Syvek pGlcNAc fiber material has chemical, physical, and biological properties that result in its favorable performance as a hemostat. Two new products, the Clo-Sur PAD and ChitoSeal, have recently become available also as patch hemostats. These two products both use chitosan, another N-acetyl glucosamine containing glycosaminoglycan, as their active ingredient. Structural, chemical, and biological comparisons of Syvek pGlcNAc and chitosan reveal a number of important differences. Syvek pGlcNAc fibers contain approximately 50 fully acetylated, high molecular weight pGlcNAc molecules in a crystalline, three-dimensional beta structure array, and are insoluble. Chitosan is a low molecular weight mixed amorphous cationic polymer with no regular structure as a solid, and is water-soluble taking on a random coil configuration when in solution. These structural dissimilarities result in differences in the hemostatic properties of the two materials. Syvek pGlcNAc is able to significantly reduce the in vitro fibrin clot formation time of platelet-rich plasma samples and has the ability to cause aggregation of red blood cells in vitro. Chitosan is no better than gauze or other controls in these in vitro assays. The Syvek Patch is able to control the bleeding and cause hemostasis in a coagulopathic swine spleen-bleeding animal model 100% of the time, whereas Clo-Sur PAD was completely unsuccessful (0%) and ChitoSeal (25%) was worse than a gauze pad control (50%) in the same model. Syvek pGlcNAc fibers have structural and chemical properties that provide a unique basis for their ability to interact with blood components to cause hemostasis. Chitosan does not have the same properties and capabilities.     

Adaptive striping watershed segmentation method for processing microscopic images of overlapping irregular‐shaped and multicentre particles

Oversegmentation is a major drawback of the morphological watershed algorithm. Here, we study and reveal that the oversegmentation is not only because of the irregular shapes of the particle images, which people are familiar with, but also because of some particles, such as ellipses, with more than one centre. A new parameter, the striping level, is introduced and the criterion for striping parameter is built to help find the right markers prior to segmentation. An adaptive striping watershed algorithm is established by applying a procedure, called the marker searching algorithm, to find the markers, which can effectively suppress the oversegmentation. The effectiveness of the proposed method is validated by analysing some typical particle images including the images of gold nanorod ensembles.     

Using the Hilbert transform for 3D visualization of differential interference contrast microscope images

Differential interference contrast (DIC) is frequently used in conventional 2D biological microscopy. Our recent investigations into producing a 3D DIC microscope (in both conventional and confocal modes) have uncovered a fundamental difficulty: namely that the phase gradient images of DIC microscopy cannot be visualized using standard digital image processing and reconstruction techniques, as commonly used elsewhere in microscopy. We discuss two approaches to the problem of preparing gradient images for 3D visualization: integration and the Hilbert transform. After applying the Hilbert transform, the dataset can then be visualized in 3D using standard techniques. We find that the Hilbert transform provides a rapid qualitative pre-processing technique for 3D visualization for a wide range of biological specimens in DIC microscopy, including chromosomes, which we use in this study.     

An analytical approach for analysis and optimisation of slider bearings with infinite width parallel textures

This paper introduces an analytical approach to study the textured surfaces in hydrodynamic lubrication regime. For this purpose, a method of integrating the Reynolds equation for slider bearings with surface discontinuities is presented. By introducing appropriate dimensionless parameters, analytical relations for various texture profiles in both indented and projected forms are delivered. These relations express the nature of mathematical dependence between textured bearing performance measures and geometrical/operational parameters. An optimisation procedure is employed to achieve the optimum texturing parameters promoting maximum load capacity, load capacity to lubricant flow rate ratio and minimum friction coefficient for asymmetric partially textured slider bearings.     

Model for the structural damping of vibrations with residual deformations

A model for the frequency-independent energy dissipation in dynamic modes of a general form, including nonstationary and wave processes, is suggested. It assumes that residual deformations can appear and allows weak and strong damping to be taken into account. A procedure for determining its parameters on the basis of experimental data is described. The influence of model parameters and cycle asymmetry on the shape of the hysteresis loop and the absorption coefficient is considered. The propagation of longitudinal vibrations along a rod is analyzed.     

Synthesis of gradient algorithms with the minimum systematic error for estimating directional fields

A method is proposed for constructing noise-resistant mask differentiating filters minimizing systematic errors in estimating directional fields by a gradient algorithm. A comparative analysis of the accuracy of gradient algorithms was performed by computer modeling It is shown that a decrease in the systematic error leads to a considerable increase in the accuracy of directional field estimation     

Search for man-made objects with the use of their structural features

The most essential constraints of conventional technologies of processing multispectral data of remote sensing of the Earth in solving the problem of searching for man-made objects are analyzed. Several methods using structural features of images of man-made objects are modeled and studied. The efficiency of approaches based on classification of fragments with the use of the Harris detectors is demonstrated.     

The coincidence counting technique for orders of magnitude background reduction in data obtained with the magnetic recoil spectrometer at OMEGA and the NIF

A magnetic recoil spectrometer (MRS) has been built and successfully used at OMEGA for measurements of down-scattered neutrons (DS-n), from which an areal density in both warm-capsule and cryogenic-DT implosions have been inferred. Another MRS is currently being commissioned on the National Ignition Facility (NIF) for diagnosing low-yield tritium-hydrogen-deuterium implosions and high-yield DT implosions. As CR-39 detectors are used in the MRS, the principal sources of background are neutron-induced tracks and intrinsic tracks (defects in the CR-39). The coincidence counting technique was developed to reduce these types of background tracks to the required level for the DS-n measurements at OMEGA and the NIF. Using this technique, it has been demonstrated that the number of background tracks is reduced by a couple of orders of magnitude, which exceeds the requirement for the DS-n measurements at both facilities.     

A four-probe method for joint measurements of components of the tensors of the conductivity and the Hall coefficient of anisotropic semiconductor films

Theoretical models of the potential distribution in rectangular semiconductor samples that characterize the features of passage of an electric current in anisotropic media were obtained. A method for joint measurements of components of the tensors of the electric conductivity and Hall coefficient of anisotropic semiconductor films was proposed.     

New type of polarization signature for radar images of the Earth cover with fractal properties

A new type of the polarization signature is proposed for estimating the anisotropy of spatial inhomogeneities of the Earth cover with the use of polarimetric radar images taken from space. The case of radar imaging of a pine forest in a decimeter band of wavelengths at different azimuthal angles is considered.     

Using a corrected least-squares procedure and accounting for structural parameters when analyzing the correlation between the impact strength of low-alloyed steels and their coercive force

The use of a corrected least-squares procedure that takes the error of impact-strength estimation into account, as well as several structure parameters, such as the equiaxial grain size number, Widmanstätten ferrite grain size number, and bainite percentage, allowed us to substantially improve the constraint equations between the impact strength and coercive force for a group of specimens. These specimens were sampled from no. 60 flange beams made of 09Г2 steel and exhibited no preliminary correlation between these parameters.     

A generalized mathematical model for the production and digitization of radiographic images

A generalized mathematical model has been developed for the production of a radiographic shadow image of a tested object followed by its conversion into a digital image using a specialized optical scanner. The model takes the staged transformation of the radiographic shadow image of the tested object into account.     

Superresolution in surveillance systems with an antenna array for synthesis of images of the Earth surface

A method that ensures superresolution in terms of angular coordinates in surveillance systems with a flat antenna array during synthesis of radio-location and radio-thermal-location images of the Earth surface with the help of an airborne station in the real beam mode is proposed. This method is based on reconstruction of reflection and emission fields.