Elliptical Areas Research Articles

Three-dimensional shakedown analysis of ballasted railway structures under moving surface loads with different load distributions

Shakedown of ballasted railway structures was analyzed based on Melan's shakedown theorem, in which the wheel/rail contact was approximated by Hertz (circular and elliptical contact areas), uniform and trapezoidal load distributions, separately. The shakedown solutions incorporating to the three-dimensional finite element model calculated shakedown multiplier by means of a self-equilibrated critical residual stress field. The shakedown multiplier for multi-layered ballasted railway structure was determined as the minimum one among all layers. The results showed that elliptical Hertz and uniform load yielded the largest and smallest shakedown limits, respectively, with the maximum difference of approximately 64%. The shakedown limits always occurred at ballast layer for relatively small frictional coefficient, whilst occurred at rail for low rail's yield stress with large frictional coefficient. As expected, the shakedown limits decreased as the ballast stiffness and thickness increased, especially for relatively small frictional coefficient; while increased with raising rail's yield stress. The material properties and thickness should therefore be optimally designed so as to provide a maximum resistance to the structure failure and reduce the material costs.

The bark anatomy of Ningxiaites specialis from the Permian of China

Bark is an important functional structure in woody plants. However, fossil tree axes are commonly decorticated. The development of bark during the evolutionary history of fossil plants thus remains poorly understood. Here, we describe exceptionally well-preserved extraxylary tissues of the Lopingian (Late Permian) conifer Ningxiaites specialis Feng, including vascular cambium and bark, from the Sunjiagou Formation (Changhsingian) of northern China. The vascular cambium bears one or two layers of cambial cells. The bark comprises secondary phloem and periderm. The secondary phloem consists of rays, axial parenchyma and sieve cells. The rays of the secondary phloem are uniseriate and continuous from the rays of the xylem. They are more frequently present in the inner zone of the secondary phloem. Axial parenchyma cells are vertically aligned and appear more regularly distributed in the outer zone of the secondary phloem. Elliptical or subcircular sieve areas are placed on the radial walls of the sieve cells. The periderm located outside the secondary phloem is composed of imbricate flattened cork cells. The cork cells show suberised cell walls and are generally filled with dark contents. Remains of the secondary phloem present between layers of periderm indicate the formation of rhytidome-type bark. This is the first detailed report of the bark anatomy of a conifer from the upper Palaeozoic of Cathaysia, and shed light on the early diversity of bark structure during the evolutionary history of conifers.

A cooperative waiting strategy based on elliptical areas for the Dynamic Pickup and Delivery Problem with Time Windows

SummaryThe purpose of this paper to present a cooperative scheduling algorithm for solving the Dynamic Pickup and Delivery Problem with Time Windows (DPDPTW). The idea behind cooperative waiting strategies is to calculate simultaneously the waiting times for all nodes in the solution. Classical non‐cooperative scheduling algorithms perform the scheduling for each route independently of the scheduling of the other routes. We present the Cooperative Scheduling Problem (CSP) based on the elliptical areas generated by vehicles waiting at their nodes. The CSP is solved by means of a genetic algorithm and is evaluated by using a set of benchmarks based on real‐life data found in the literature. Initially, two waiting strategies are presented: Wait‐Early‐Time scheduling and Balanced‐Departure scheduling. Extensive empirical simulations have been carried out by analyzing the degree of dynamism and the average waiting time, a new concept defined to take into account the gap between the time windows of pickup and delivery nodes. Copyright © 2016 John Wiley & Sons, Ltd.

Analysis of Soccer Players' Positional Variability During the 2012 UEFA European Championship: A Case Study.

The purpose of this study was to analyse players’ positional variability during the 2012 UEFA European Championship by applying principal component analysis (PCA) to data gathered from heat maps posted on the UEFA website. We analysed the teams that reached the finals and semi-finals of the competition. The players’ 2D coordinates from each match were obtained by applying an image-processing algorithm to the heat maps. With all the players’ 2D coordinates for each match, we applied PCA to identify the directions of greatest variability. Then, two orthogonal segments were centred on each player’s mean position for all matches. The segments’ directions were driven by the eigenvectors of the PCA, and the length of each segment was defined as one standard deviation around the mean. Finally, an ellipse was circumscribed around both segments. To represent player variability, segment lengths and elliptical areas were analysed. The results demonstrate that Portugal exhibited the lowest variability, followed by Germany, Spain and Italy. Additionally, a graphical representation of every player’s ellipse provided insight into the teams’ organisational features throughout the competition. The presented study provides important information regarding soccer teams’ tactical strategy in high-level championships that allows coaches to better control team organisation on the pitch.

Ещё раз об автоматической расшифровке рентгеновских снимков сварных швов

Introduction. This article is dedicated to a possible approach to automatic inspection of welded joints X-Ray images. This problem is very urgent but there is no established practice of the automated X-Ray images inspection and image objects recognition. The purpose of the article was to highlight the tasks included in the X-Ray interpretation process that can be automated, and to offer possible solutions. 
 Method. Analysis and interpretation of images were made using "X-Vizor" software by “Newcom-NDT”.
 Results. Studies have shown that the straight and elliptical seam areas could be recognized automatically. It provides the possibility for a signal-noise ratio to be automatically measured. Wire image quality indicators and grooving gages also could be recognized automatically in approximately 80% cases. So it is possible to automatically calculate the sensitivity of the inspection. It is also achievable to automatically determine the basic spatial resolution using duplex wire image quality indicator. But the task of automation of defect recognition is still not solved. The possible alternative was offered. It is semi automation of defects recognition and analysis. This procedure needs the human to take part in image interpretation process. 
 Conclusion. The conclusion is that the total automation of digital X-Ray image interpretation of welded joints is now unavailable. Nevertheless using automation algorithms in all parts of interpretation process where it is possible can highly increase the performance of the inspection and its reliability.

Bed Net Durability Assessments: Exploring a Composite Measure of Net Damage.

BackgroundThe durability of Long Lasting Insecticidal Nets (LLINs) in field conditions is of great importance for malaria prevention and control efforts; however, the physical integrity of the net fabric is not well understood making it challenging to determine overall effectiveness of nets as they age. The 2011 World Health Organization Pesticide Evaluation Scheme (WHOPES) guidelines provide a simple, standardized method using a proportional hole index (PHI) for assessing net damage with the intent to provide national malaria control programs with guidelines to assess the useful life of LLINS and estimate the rate of replacement.MethodsWe evaluated the utility of the PHI measure using 409 LLINs collected over three years in Nampula Province, Mozambique following a mass distribution campaign in 2008. For each LLIN the diameter and distance from the bottom of the net were recorded for every hole. Holes were classified into four size categories and a PHI was calculated following WHOPES guidelines. We investigate how the size, shape, and location of holes influence the PHI. The areas of the WHOPES defined categories were compared to circular and elliptical areas based on approximate shape and actual measured axes of each hole and the PHI was compared to cumulative damaged surface area of the LLIN.ResultsThe damaged area of small, medium, large, and extra-large holes was overestimated using the WHOPES categories compared to elliptical areas using the actual measured axes. Similar results were found when comparing to circular areas except for extra-large holes which were underestimated. (Wilcoxon signed rank test of differences p< 0.0001 for all sizes). Approximating holes as circular overestimated hole surface area by 1.5 to 2 times or more. There was a significant difference in the mean number of holes < 0.5 cm by brand and there were more holes of all sizes on the bottom of nets than the top. For a range of hypothetical PHI thresholds used to designate a “failed LLIN”, roughly 75 to 80% of failed LLINs were detected by considering large and extra-large holes alone, but sensitivity varied by brand.ConclusionsFuture studies may refine the PHI to better approximate overall damaged surface area. Furthermore, research is needed to identify whether or not appropriate PHI thresholds can be used to deem a net no longer protective. Once a cutoff is selected, simpler methods of determining the effective lifespan of LLINs can help guide replacement strategies for malaria control programs.

Static postural control assessment during pregnancy

&lt;p&gt;The hormonal and anatomic changes during pregnancy affect the musculoskeletal system and may lead to instability of static postural control and increased risk of falls. The aim of this study was to analyze changes in static postural control during the three trimesters of pregnancy, using variables derived from the center of pressure. This is a descriptive study in which posturographic tests were applied in four still standing positions, for three trials, with a combination of different visual conditions (eyes open - EO/eyes closed - EC) and support base configurations on 20 non-pregnant women (C) and 13 pregnant women during the gestational period (G1, G2 and G3). For static postural control assessment, a force plate (Bertec®) was used, and the variables analyzed were statokinesigram area, displacement amplitude, displacement velocity and sway frequency. The results demonstrate that, early in pregnancy, the woman's body seems to already change postural control, probably due to increased mobility of the sacroiliac joint and pubic symphysis caused by hormonal factors, and during the trimesters there is a decrease in postural stability, observed as an increase in the elliptical areas, amplitudes of center of pressure displacement and velocity of center of pressure displacement.&lt;/p&gt;

Static postural control assessment during pregnancy

The hormonal and anatomic changes during pregnancy affect the musculoskeletal system and may lead to instability of static postural control and increased risk of falls. The aim of this study was to analyze changes in static postural control during the three trimesters of pregnancy, using variables derived from the center of pressure. This is a descriptive study in which posturographic tests were applied in four still standing positions, for three trials, with a combination of different visual conditions (eyes open - EO/eyes closed - EC) and support base configurations on 20 non-pregnant women (C) and 13 pregnant women during the gestational period (G1, G2 and G3). For static postural control assessment, a force plate (Bertec®) was used, and the variables analyzed were statokinesigram area, displacement amplitude, displacement velocity and sway frequency. The results demonstrate that, early in pregnancy, the woman's body seems to already change postural control, probably due to increased mobility of the sacroiliac joint and pubic symphysis caused by hormonal factors, and during the trimesters there is a decrease in postural stability, observed as an increase in the elliptical areas, amplitudes of center of pressure displacement and velocity of center of pressure displacement.

Tidal volume monitoring by electrical impedance tomography (EIT) using different regions of interest (ROI): Calibration equations

A set of calibration equations was previously obtained to transform the lung impedance changes obtained by electrical impedance tomography (EIT), using all frame's elements, into a measurable volume signal. In order to study the goodness of the use of regions of interest (ROI) for lung ventilation monitoring, we considered 6 different ROI to obtain a calibration equation for each area. Our aim was to compare the results, determined by these areas, and those obtained by using all EIT image elements. Two ROI's were defined by those pixels with an impedance change higher than 30% and 70% of the maximum change value. These areas were called P30 and P70, respectively. Two other ROI were defined by bounding two areas by mouse, resembling P30 and P70 regions, which were called M30 and M70, respectively. The remainder was defined by two elliptical areas with an eccentricity of 0.8, and 25 and 32 pixels of mayor axis (E25p and E32p, respectively). Twenty healthy males and 24 chronic obstructive pulmonary disease (COPD) patients were considered. For small region (P30 and M30) we obtained a large dispersion in volume measurement, concluding that small regions are not suitable for monitoring the tidal changes in lung volume even for healthy subjects. The results obtained by the remainder areas, and by using EIT image were similar. Even a slight improvement in data dispersion was obtained by using some ROI. These optimal results, for healthy people, were those corresponding to P70 and M70 (volume dispersion improved from 12% with the whole EIT image to 9% using ROI), and for COPD patients improves volume dispersion from 32% using the whole EIT image to 27% by using E25p. Using not so small ROI, it is possible to estimate the total lung ventilation.

Identification of potential locations for well placement in developed coalbed methane reservoirs

This study investigates well placement in developed coalbed methane (CBM) reservoirs. A workflow is developed to find potential locations for well placement within the reservoir. It consists of a reservoir simulator and statistical analysis. The application of this workflow is to reduce the need to perform computationally expensive simulations in large reservoirs to obtain potential locations for drilling an additional well. The workflow is also used to study the role of dominant reservoir properties in finding potential locations for well placement. The effects of permeability anisotropy, gas and water relative permeabilities, sorption time, and water content in well placement are discussed.Results demonstrate that permeability anisotropy results in the formation of elliptical drainage areas around the wells. When drainage patterns are orthogonal to the direction of placement of wells, the drainage area of the reservoir is large and penetrated into distant locations. This leads to a non-uniform drainage area and extends well placement options to distant locations. Comparison between well placement in two scenarios with different gas and water relative permeabilities shows that potential locations tend to be on a border region between existing wells and virgin area when water mobility is restricted by water relative permeabilities. This region has the advantage of having higher pressure and gas content compared to locations among existing wells. In this study, changing the sorption time does not affect the well placement within the reservoir. Except at very early times, gas production from presented reservoir models is mainly controlled by Darcy flow in cleat system (permeability-dominated) rather than diffusion process in coal matrix.

The soft-tissue attachment scars in Late Jurassic ammonites from Central Russia

Soft-tissue attachment scars of two genera and four species of Late Jurassic craspeditid ammonites from the Russian Platform are described. A previously suggested relationship between lateral attachment scars and ammonoid hyponome is confirmed, however, a new interpretation is proposed for dorsal attachment scars: they could have been areas not only for attachment of the dorsal (nuchal) retractors, but also of the cephalic retractors. The new type of the soft-tissue attachment—anterior lateral sinuses, located between the lateral attachment scars and the aperture of the ammonite body chamber is described. Enclosed elliptical or subtriangular areas in apertural parts of the anterior lateral sinuses were found for the first time. Their presence and location suggest that this structure could have been used for attaching the funnel-locking apparatus, similar to those of coleoids. A transformation of shape and position of lateral attachment scars through the evolution of the Late Jurassic craspeditid lineage s...

Sono-myography and Sono-myoelastography of the Tender Points of Women with Fibromyalgia

Sono-myography and sono-myoelastography have been found useful in the investigation of myofascial trigger points. The objective of this study was to use the same techniques to investigate the morphology, stiffness and blood flow of tender points in women with fibromyalgia and to compare the results with those for samples from healthy patients. Algometry tests indicated significant differences between groups (p<0.001). Elliptical and hypoechoic areas were observed in the ultrasound images of the upper trapezius in both groups. No differences between groups were found in the number of hypoechoic areas (p=0.167, t=1.008); blood flow also did not differ between the groups. Larger hypoechoic areas were found in the fibromyalgia group (p=0.139, t=1.317). Sono-myoelastography did not reveal greater stiffness in these areas compared with the rest of the muscle. These results lead us to believe that sono-myoelastography and sono-myography, used in the diagnosis of myofascial trigger points, may not be able to discriminate tender points.

Lateral self-assembly of 18.5-kDa myelin basic protein (MBP) charge component-C1 on membranes

Myelin basic protein (MBP), particularly the classic 18.5-kDa isoform, is a major structural protein of the myelin sheath of the central nervous system. It is an intrinsically disordered, peripheral membrane protein that shows structural polymorphism in combination with several overlapping interaction sites. Here, double electron–electron resonance (DEER) spectroscopy, in combination with a simplified, semi-quantitative analysis based on Monte Carlo simulations, is used to determine the distance distribution of murine 18.5-kDa MBP, unmodified charge component-C1, on large unilamellar vesicles of a lipid composition mimicking the cytoplasmic leaflet of myelin. Three singly spin-labeled MBP variants and a mixture of singly-labeled MBP variants are used. The MBPs, each bearing only one spin label, exhibit average intermolecular distances that are significantly shorter than the distances expected when assuming a random distribution at the employed lipid-to-protein ratios, indicating self-assembly on the membrane. The distribution of elliptical pervaded areas (hard ellipses) on a two-dimensional surface can serve as a model of the nonspecific self-assembly process. The corresponding pair correlation functions g(r) are determined from Monte Carlo simulations with variation of various parameters such as the ellipses' aspect ratios. Comparing the g(r) values with the DEER-derived distance distributions, the pervaded volume is best characterized by a nearly elliptical projection onto the membrane, with an aspect ratio of approximately 1.5, and with the longer semi-axis of approximately 1.4nm. The approach of using local information from DEER with low-resolution models derived from Monte Carlo simulations can be applied to study the lateral self-assembly properties of other protein complexes on membranes.

Lamb wave interactions through dispersion 2D filters

Acoustic surface waves are widely used to sense and map the properties of the propagation media. In order to characterise local space-time waves, methods such as Gabor analysis are powerful. Nevertheless, knowing which wave is observed, extracting its full bandwidth contribution from the others and to map it in the signal domain is also of great interest. In the Fourier domain, the acoustic energy of a wave is concentrated along the wave-number frequency (k-ω) dispersion curve, a way to extract one wave from others is to filter the signals by mean of k-ω band-pass area that keeps only the selected surface wave. The objective of the present paper is to propose 2D Finite Impulse Response (FIR) filters based on an arbitrary area shape designed to extract selected waves. FIR filtering is based on convolving the impulse response of the filter with the signals. Impulse responses derived from using k-ω elliptical areas (E-FIR) are presented. The E-FIR filters are successfully tested on three experimental space-time signals corresponding to the propagation of Lamb waves measured by standard transducers on a cylindrical shell, by laser Doppler on a plate and generated by a circular pulse and observed by shearography on a rectangular plate.

Spatiotemporal Analysis of Macroscopic Patterns of Urbanization and Traffic Safety

This study provides a preliminary investigation into the relationship between urbanization and traffic collisions by analyzing the spatial patterns in Sacramento County, California, from 1998 to 2008 through use of urban land classifications and traffic collision data. The ArcGIS directional distribution tool was used to create standard deviational ellipses to investigate the distributional trend of urban land and traffic collisions over time. Statistical outputs representing changes of geographical centroids, elliptical areas, and standard distances (long and short axes) were then compared. Collisions were also divided into subsets by severity level to account for inherent differences in the spatial distribution of different types of collisions. The results provided insight into the macroscopic spatial patterns of urban land and traffic safety and their relationships. The limitations of the method and the need for further research were discussed. The approach in this study would be useful for other metropolitan areas with similarly changing development patterns and can be helpful in guiding future research that compares these two phenomena.

Intercomparison Study of Cloud-to-Ground Lightning Flashes Observed by KARITLDS and KLDN at South Korea

Abstract Concern regarding lightning activity as a precursor of severe weather is increasing. Atmospheric electricity, including lightning phenomena, is one of most serious threats to successful space launch operations. The objective of this study was to evaluate the performance of two different lightning detection networks using a time–range correlation method. Understanding lightning detection network performance enables the weather forecaster to support decisions made regarding space launch operations. The relative detection efficiency (ReDE), observation ratio, ellipse area for 50% probability of location, number of sensors reporting (NSR), time difference, and distance, as parameters that predict system performance, were calculated with the time-range correlation method using cloud-to-ground (CG) flash data from the Korea Aerospace Research Institute Total Lightning Detection System (KARITLDS) and from the Korean Meteorology Administration Lightning Detection Network (KLDN). In this study, 15 thunderstorms were selected from 2008–09 data. A total of 41 192 and 28 976 CG flashes were recorded by KARITLDS and KLDN, respectively. In all, 19 044 CG flashes were correlated as being the same flash. The observation ratios, ReDEKARITLDS, and ReDEKLDN were calculated as 1.42, 0.66, and 0.46, respectively. Eighty percent of CG flashes detected by the KARITLDS (KLDN) had elliptical areas less than 5 km2 (12 km2), where the elliptical areas were defined as having a 50% probability of containing the CG flash. Two regions showing a high observation ratio were due to high KARITLDS detection efficiency and to the blocking of electromagnetic wave propagation by Mount Hanla at 1950 m above sea level.

Elastic-Plastic Microcontact Model for Elliptical Contact Areas and Its Application to a Treillis Point in Overhead Electrical Conductors

Aeolian vibrations represent a threat to the integrity of electrical transmission lines. The fretting fatigue of conductors is thus a major concern. The modelization of the contact conditions at critical points is an important tool in assessing the life of conductors. Treillis points around the last point of contact between the conductor and the pieces of equipment are such critical points. We observe a fully plastic contact condition at these points. Finite element results for the contact between an ellipsoid and a rigid plane and between two wires at different angles are compared with an elastic-plastic microcontact model for elliptical contact areas. These numerical results are then compared with experimental ones for the contact between two wires of a conductor (ACSR Bersfort), showing a very similar relationship between the contact force and the observed contact area. We have a good correlation between the microcontact model and the finite elements ones in the fully plastic contact regime on both the contact area and the contact force for a given interference between bodies. The use of the elastic-plastic microcontact model for elliptical contacts presented in this paper proves to be a strong tool in getting a better understanding of the mechanical behavior at those critical points.

3D Face Recognition Using Simulated Annealing and the Surface Interpenetration Measure

This paper presents a novel automatic framework to perform 3D face recognition. The proposed method uses a Simulated Annealing-based approach (SA) for range image registration with the Surface Interpenetration Measure (SIM), as similarity measure, in order to match two face images. The authentication score is obtained by combining the SIM values corresponding to the matching of four different face regions: circular and elliptical areas around the nose, forehead, and the entire face region. Then, a modified SA approach is proposed taking advantage of invariant face regions to better handle facial expressions. Comprehensive experiments were performed on the FRGC v2 database, the largest available database of 3D face images composed of 4,007 images with different facial expressions. The experiments simulated both verification and identification systems and the results compared to those reported by state-of-the-art works. By using all of the images in the database, a verification rate of 96.5 percent was achieved at a False Acceptance Rate (FAR) of 0.1 percent. In the identification scenario, a rank-one accuracy of 98.4 percent was achieved. To the best of our knowledge, this is the highest rank-one score ever achieved for the FRGC v2 database when compared to results published in the literature.

Detecting Mitoses in Time-Lapse Images of Embryonic Epithelia Using Intensity Analysis

Although the frequency and orientation of mitoses can significantly affect the mechanics of early embryo development, these data have not been available due to a shortage of suitable automated techniques. Fluorescence imaging, though popular, requires biochemical intervention and is not always possible or desirable. Here, a new technique that takes advantage of a localized intensity change that occurs in bright field images is used to identify mitoses. The algorithm involves mapping a deformable, sub-cellular triangular mesh from one time-lapse image to the next so that corresponding regions can be identified. Triangles in the mesh that undergo darkening of a sufficient degree over a period consistent with mitosis are flagged. Mitoses are assumed to occur along the short axis of elliptical areas fit to suitably sized clusters of flagged triangles. The algorithm is less complex than previous approaches and it has strong discrimination characteristics. When applied to 15 image sets from neurulation-stage axolotl (Ambystoma mexicanum) embryos, it was able to correctly detect 86% of the manually identified mitoses, had less than 5% false positives and produced average angular errors of only 15 degrees . The new algorithm is simpler to implement than those previously available, is substantially more accurate, and provides data that is important for understanding the mechanics of morphogenetic movements.

Evidence of fungal activity in silicified gymnosperm wood from the Eocene of southern Patagonia (Argentina)

Evidence of fungal activity expressed as typical decay patterns is described from silicified podocarpaceous wood from the Eocene of Patagonia, Argentina. Decay features consist of tracheids of the secondary xylem that are degraded, resulting in thin-celled, lignin-free, translucent, circular to elliptical areas, some of which have cells devoid of all cell wall components including lignin, hemicellulose, and cellulose, and other areas that show only partial simultaneous decay of all cell wall layers. These patterns conform to the white rot and its variant white pocket rot decay patterns produced by basidiomycetes and ascomycetes in gymnosperm and angiosperm wood in modern terrestrial ecosystems. Coagulated opaque bodies in the lumen of some cells and enlarged secondary walls may represent host reactions to infection or remains of metabolic products of fungal enzymatic activity. Similar decay patterns and reaction features have been described from fossil woods ranging in age from the Devonian to the present. This record expands the fossil record of wood rot fungi and underscores their importance as drivers of biological cycles in ancient terrestrial ecosystems.