Ellipse Model Research Articles

Embedded Spiral Patterns in the Cool Core of the Massive Cluster of Galaxies Abell 1835

Abstract We present the properties of an intracluster medium (ICM) in the cool core of the massive cluster of galaxies, Abell 1835, obtained with the data from the Chandra X-ray Observatory. We find distinctive spiral patterns with a radius of 70 kpc (or 18″) as a whole in the residual image of the X-ray surface brightness after the two-dimensional ellipse model of surface brightness is subtracted. The size is smaller by a factor of 2–4 than that of other clusters that are known to have a similar pattern. The spiral patterns consist of two arms. One of them appears as positive, and the other appears as negative excesses in the residual image. Their X-ray spectra show that the ICM temperatures in the positive- and negative-excess regions are keV and keV, respectively. In contrast, no significant difference is found in the abundance or pressure, the latter of which suggests that the ICM in the two regions of the spiral patterns is near or is in pressure equilibrium. The spatially resolved X-ray spectroscopy of the central region ( ), divided into 92 sub-regions indicates that Abell 1835 is a typical cool core cluster. We also find that the spiral patterns extend from the cool core out to the hotter surrounding ICM. The residual image reveals some lumpy substructures in the cool core. The line of sight component of the disturbance velocity that is responsible for the substructures is estimated to be lower than 600 km s−1. Abell 1835 may now be experiencing an off-axis minor merger.

Integrated finite element simulation and experiment verification of the large-sized straight welded pipe processing with JCOE technology

The integrated and continuous finite element simulations of the JCOE forming technology (progressive forming process of ‘J’ forming, ‘C’ forming and ‘O’ forming, reducing gap, welding and mechanical expanding) for large-sized straight welded pipe are implemented based on the MARC software. The simulation results of the JCO continuous model and simplified as ellipse model are compared with the production results, which indicates that the section contour and sticking state between the expander die and inner wall of the tube for continuous model are more close to the production results. The area in the suspended zone is in the tensile bending deformation state and the residual stress in the suspended zone is mainly concentrated in the outer layer. Taking the relative expander die radius (the ratio of expander die radius and the inner radius of finished welded pipe) and expanding ratio as variables, the expanding process of the JCO continuous model is simulated. The results indicate that, when the relative expander die radius is 1.05, the deformation of the pipe is uniform and the larger of the expanding ratio, the lower the residual stress when the expanding ratio is in the range 0.8–1.7.

A statistical study on the shape and position of the magnetotail neutral sheet

Abstract. We study the average shape and position of the magnetotail neutral sheet based on magnetic field data obtained by Cluster, Geotail, TC-1, and THEMIS from the years 1995 to 2013. All data in the aberrated GSM (geocentric solar magnetospheric) coordinate system are normalized to the same solar wind pressure 2 nPa and downtail distance X ∼ −20RE. Our results show characteristics of the neutral sheet, as follows. (1) The neutral sheet assumes a greater degree of curve in the YZ cross section when the dipole tilt increases, the Earth dipole tilt angle affects the neutral sheet configuration not only in the YZ cross section but also in the XY cross section, and the neutral sheet assumes a more significant degree of tilt in the XY cross section when the dipole tilt increases. (2) Counterclockwise twisting of the neutral sheet with 3.10° is observed, looking along the downtail direction, for the positive interplanetary magnetic field (IMF) BY with a value of 3 to 8 nT, and clockwise twisting of the neutral sheet with 3.37° for the negative IMF BY with a value of −8 to −3 nT, and a northward IMF can result in a greater twisting of the near-tail neutral sheet than southward. The above results can be a reference to the neutral sheet model. Our large database also shows that the displaced ellipse model is effective to study the average shape of the neutral sheet with proper parameters when the dipole tilt angle is larger (less) than 10° (−10° ).

An integrative modeling approach for the efficient estimation of cross sectional tibial stresses during locomotion

The purpose of this research was to utilize a series of models to estimate the stress in a cross section of the tibia, located 62% from the proximal end, during walking. Twenty-eight male, active duty soldiers walked on an instrumented treadmill while external force data and kinematics were recorded. A rigid body model was used to estimate joint moments and reaction forces. A musculoskeletal model was used to gather muscle length, muscle velocity, moment arm and orientation information. Optimization procedures were used to estimate muscle forces and finally internal bone forces and moments were applied to an inhomogeneous, subject specific bone model obtained from CT scans to estimate stress in the bone cross section. Validity was assessed by comparison to stresses calculated from strain gage data in the literature and sensitivity was investigated using two simplified versions of the bone model-a homogeneous model and an ellipse approximation. Peak compressive stress occurred on the posterior aspect of the cross section (−47.5±14.9MPa). Peak tensile stress occurred on the anterior aspect (27.0±11.7MPa) while the location of peak shear was variable between subjects (7.2±2.4MPa). Peak compressive, tensile and shear stresses were within 0.52MPa, 0.36MPa and 3.02MPa respectively of those calculated from the converted strain gage data. Peak values from a inhomogeneous model of the bone correlated well with homogeneous model (normal: 0.99; shear: 0.94) as did the normal ellipse model (r=0.89–0.96). However, the relationship between shear stress in the inhomogeneous model and ellipse model was less accurate (r=0.64). The procedures detailed in this paper provide a non-invasive and relatively quick method of estimating cross sectional stress that holds promise for assessing injury and osteogenic stimulus in bone during normal physical activity.

Thrust distribution characteristics of thrust systems of shield machines based on spatial force ellipse model in mixed ground

The objective of this research is to investigate force distribution characteristics for propelling system of tunneling machines in mixed ground. First, a mechanical model for pushing system in composite strata is constructed. Then, eccentricity trunk is determined using spatial force ellipse eccentricity to measure the degree of uniformity of forces applied on rear segments in a thrust system. Finally, the eccentricity trunk is used to the thrust system of a tunneling machine applied in engineering. Force distribution performance of various arrangements with equal quantities of jacks is discussed in detail. Results from virtual prototype simulation prove the numerical analytical results. A theoretical foundation and support is provided for the design of non-equidistant pushing system of tunneling machines under composite stratum.

Perturbed motion at small eccentricities

In the study of the motion of planets and moons, it is often necessary to have a simple approximate analytical motion model, which takes into account major perturbations and preserves almost the same accuracy at long time intervals. A precessing ellipse model is used for this purpose. In this paper, it is shown that for small eccentricities this model of the perturbed orbit does not correspond to body motion characteristics. There is perturbed circular motion with a constant zero mean anomaly. The corresponding solution satisfies the Lagrange equations with respect to Keplerian orbital elements. There are two families of solutions with libration and circulation changes in the mean anomaly close to this particular solution. The paper shows how the eccentricity and mean anomaly change in these solutions. Simple analytical models of the motion of the four closest moons of Jupiter consistent with available ephemerides are proposed, which in turn are obtained by the numerical integration of motion equations and are refined by observations.

Automatic Measurement of Venous Pressure Using B-Mode Ultrasound.

Central venous pressure (CVP) information is crucial in clinical situations, such as cardiac failure, intravascular volume overload, and sepsis. The measurement of CVP, however, requires the catheterization of vena cava through the subclavian or internal jugular veins, which is an impractical and costly procedure with related risk of complications. Peripheral venous pressure (PVP), which correlates with CVP under certain patient positioning, can be measured noninvasively using ultrasound via controlled compressions of a superficial vein. This paper presents an automatic system for acquiring such noninvasive measurements. Robust signal and image processing techniques developed for this purpose are introduced in this paper. The proposed standalone mobile platform collects images in real time from the display output of any ultrasound machine, meanwhile measuring the pressure on the skin underneath the ultrasound transducer via a liquid-filled pouch. The image and pressure data are synchronized through an automated temporal calibration procedure. During forearm compressions, blood vessels are detected and tracked in the images using robust geometric (ellipse) models, the parameters of which are used further in the model-based estimation of PVP. The proposed system was tested in 56 image sequences on 14 healthy volunteers, and was shown to achieve measurements with errors comparable to or lower than the interoperator variability of expert manual assessments.

Fast semi-automatic segmentation of focal liver lesions in contrast-enhanced ultrasound, based on a probabilistic model

Assessment of focal liver lesions (FLLs) in contrast-enhanced ultrasound requires the delineation of the FLL in at least one frame of the acquired data, which is currently performed manually by experienced radiologists. Such a task leads to subjective results, is time-consuming and prone to misinterpretation and human error. This paper describes an attempt to improve this clinical practice by proposing a novel fast two-step method to automate the FLL segmentation, initialised only by a single seed point. Firstly, rectangular force functions are used to improve the accuracy and computational efficiency of an active ellipse model for approximating the FLL shape. Then, a novel probabilistic boundary refinement method is used to iteratively classify boundary pixels rapidly. The proposed method allows for faster and easier assessment of FLLs, whilst requiring less interaction, but producing results comparably consistent with manual delineations, and hence increasing the confidence of radiologists when making a diagnosis. Quantitative evaluation based on real clinical data, from two different European countries reflecting true clinical practice, demonstrates the value of the proposed method.

Modelling animal movement using the Argos satellite telemetry location error ellipse

Summary The Argos satellite telemetry system is popular for studying the movement and space use of marine animals. The life histories of marine mammals, in particular, result in a relatively large proportion of inaccurate locations, thus making analysis methods that do not account for location measurement error inappropriate for these data. Using a new Kalman filtering algorithm, Argos now provides locations and estimated error ellipses associated with each satellite fix, but to our knowledge, the location error ellipse has yet to be incorporated into analyses of animal movement or space use. We first present an observation model utilizing the Argos error ellipse and then demonstrate how this observation model can be combined with a simple three‐dimensional movement model in a state‐space formulation to infer activity budgets and movement characteristics from location and dive data of two species of seal, the bearded seal (Erignathus barbatus) and the Hawaiian monk seal (Monachus schauinslandi). These example data sets are of variable quality and represent species that differ in both space use and latitudinal range relative to the polar orbits of Argos satellites. We also compare the results from our error ellipse model with those from an approximate (isotropic) error circle model. We found the error circle to be a crude approximation of the actual anisotropic error ellipse for the higher quality bearded seal data, but inferences from the lower quality Hawaiian monk seal data were more robust to the choice of observation model. In both examples, we found the theoretical bivariate normal distribution corresponding to the error ellipse often failed to adequately explain the most extreme location outliers. In practice, we suspect the inferential consequences of using traditional isotropic location quality classes or other crude approximations in lieu of the error ellipse will be largely case‐dependent. We support the Argos recommendation that practitioners wishing to more properly account for location measurement error utilize the error ellipse in analyses. However, the continued presence of outliers using the new algorithm suggests practitioners should consider using a fat‐tailed distribution derived from the error ellipse (e.g. bivariate t‐distribution) or filtering extreme outliers during data pre‐processing.

Mechanism Design and Manipulating Algorithm for Orientation Changing Module with Three Flexible Links

This paper presents mechanism and control algorithm for inch worm type in-pipe robot using three helical springs. Control algorithm is based on experiment result and length of three spring are derived from desired position of top module. A feasibility of proposed mechanism is verified by comparing between ellipse model and position of top module, and it shows that proposed mechanism can steer properly.

Experimental study on the dynamics of polarized strong optical injection in 1550 nm VCSELs.

We have experimentally analyzed the dynamics of polarized strong optical injection in 1550 nm vertical-cavity surface-emitting lasers (VCSELs). The locking ranges of optical injection-locked (OIL) VCSELs are experimentally measured in different states of polarized strong optical injection. Based on our novel ellipse model, the influence of the polarization state of strong injection light is quantitatively studied for the first time.

PENGGUNAAN MODEL STANDARD DEVIATIONAL ELLIPSE (SDE) PADA ANALISIS KASUS PENYAKIT DEMAM BERDARAH DENGUE DI KOTA BANJAR TAHUN 2013

Dengue Fever Disease is still regarded as an endemic disease in Banjar City. Information is still required to map dengue fever case distribution, mean center of case distribution, and the direction of dengue fever case dispersion in order to support the surveillance program in the relation to the vast area of the dengue fever disease control program. The objective of the research is to obtain information regarding the area of dengue fever disease distribution in Banjar City by utilizing the Standard Deviational Ellipse (SDE) model. The research is an observational study with Explanatory Spatial Data Analysis (ESDA). Data analysis uses SDE model with the scope of the entire sub district area in Banjar City. The data analyzed is dengue fever case from 2007-2013 periods, with the number of sample of 315 cases. Social demographic overview of dengue fever patients in Banjar City shows that most of the patients are within the productive age, with 39.7% within the school age and 45.7% are within the work age. Most of the dengue fever patients are men (58.1%). Distribution of dengue fever cases from the period of 2007 until 2012 mostly occur in 25-37.5 meters above sea level (MASL) (55.8%). The SDE models of dengue fever cases in Banjar City generally form dispersion patterns following the x-axis and clustered by physiographic boundaries. The SDE model can be used to discover dispersion patterns and directions of dengue fever cases, therefore, dengue fever disease control program can be conducted based on local-specific information, in order to support health decision. Keywords: model, mapping, Standard Deviational Ellipse, dengue fever, Banjar City

Study of Phase Function of the Biological Cell

In order to settle the influence of measuring results of cells with its shape-variety in the examination of biological cell, MCEM (modify co-central ellipse model) is adopted based on the theories of Rayleigh-Debye-Gans, and the changing tendency of scattering phase function of nucleated cells with different body factor, nuclear size and shooting angle are studied. These provide a useful theory foundation for improving the measurement and distinguishing of biological cell.

Video-Based Tracking, Learning, and Recognition Method for Multiple Moving Objects

This paper presents an extended Markov chain Monte Carlo (MCMC) method for tracking and an extended hidden Markov model (HMM) method for learning/recognizing multiple moving objects in videos with jittering backgrounds. A graphical user interface (GUI) with enhanced usability is also proposed. Previous MCMC and HMM-based methods are known to suffer performance impairments, degraded tracking and recognition accuracy, and higher computation costs when challenged with appearance and trajectory changes such as occlusion, interaction, and varying numbers of moving objects. This paper proposes a cost reduction method for the MCMC approach by taking moves, i.e., birth and death, out of the iteration loop of the Markov chain when different moving objects interact. For stable and robust tracking, an ellipse model with stochastic model parameters is used. Moreover, our HMM method integrates several different modules in order to cope with multiple discontinuous trajectories. The GUI proposed herein offers an auto-allocation module of symbols from images and a hand-drawing module for efficient trajectory learning and for interest trajectory addition. Experiments demonstrate the advantages of our method and GUI in tracking, learning, and recognizing spatiotemporal smooth and discontinuous trajectories.

Modeling the Relationship Between Neutron Counting Rates and Sunspot Numbers Using the Hysteresis Effect

Several studies show that temporal variations in the Galactic cosmic ray (GCR) intensity display a distinct 11-year periodicity due to solar modulation of the galactic cosmic rays in the heliosphere. The 11-year periodicity of GCRs is inversely proportional to, but out of phase with, the 11-year solar cycle, implying that there is a time lag between actual solar cycle and the GCR intensity, which is known as the hysteresis effect. In this study, we use the hysteresis effect to model the relationship between neutron counting rates (NCRs), an indicator of the GCR intensity, and sunspot numbers (SSNs) over the period that covers the last four solar cycles (20, 21, 22, and 23). Both linear and ellipse models were applied to SSNs during odd and even cycles in order to calculate temporal variations of NCRs. We find that ellipse modeling provides higher correlation coefficients for odd cycles compared to linear models, e.g. 0.97, 0.97, 0.92, and 0.97 compared to 0.69, 0.72, 0.53, and 0.68 for data from McMurdo, Swarthmore, South Pole, and Thule neutron monitors, respectively, during solar cycle 21 with overall improvement of 31 % for odd cycles. When combined to a continuous model, the better correlation observed for the odd cycles increases the overall correlation between observed and modeled NCRs. The new empirical model therefore provides a better representation of the relationship between NCRs and SSNs. A major goal of the ongoing research is to use the new non-linear empirical model to reconstruct SSNs on annual time scales prior to 1610, where we do not have observational records of SSNs, based on changes in NCRs reconstructed from 10Be in ice cores.

Segmentation-based heart sound feature extraction combined with classifier models for a VSD diagnosis system

In this paper, boundary curve models for the diagnostic features [T12,T11] and [FG,FW] are proposed to diagnose ventricular septal defects (VSD), which are generally divided into 3 types: small VSD (SVSD), moderate VSD (MVSD) and large VSD (LVSD). The VSD diagnosis is accomplished in three steps. First, in the time domain, the diagnostic features [T12,T11], which are the time intervals between two adjacent first heart sounds (S1) as well as the interval between S1 and the second heart sound (S2), are extracted from the envelope ET for the heart sound (HS); in the frequency domain, the envelope EF for every cardiac cycle sound that the HS is segmented into, based on a moving windowed Hilbert transform (MWHT), is proposed to extract the diagnostic features [FG,FW], which are the center of gravity and the frequency width of the frequency distribution. Second, to evaluate the detection ability of the proposed diagnostic features, a classification boundary method based on the support vector machines (SVM) technique is proposed to determine the classifiers to diagnose the VSD sounds. Furthermore, to simplify these classifiers and make them parameterizable, according to their shapes, the least squares method is employed to build ellipse models for fitting the classification boundary curves. Finally, the numerical results based on the ellipse models are introduced for diagnosis of the VSD. Moreover, to validate the usefulness of the proposed method for sounds besides VSD and normal sounds, aortic regurgitation (AR), atrial fibrillation (AF), aortic stenosis (AS) and mitral stenosis (MS) sounds are used as examples to be detected. As a result, the classification accuracies (CA) achieved is 98.4% for the detection of clinical VSD sounds from normal sounds and are 95.1%, 94.8% and 95.0%, respectively, for the detection of clinical SVSD, MVSD, and LVSD among VSD sounds.

Top-View-Based Guidance for Blind People Using Directional Ellipse Model

The guidance system proposed in this paper aims to complement the white cane by monitoring road conditions in a medium range for blind pedestrians in real time. The system prototype employs only one webcam fixed at the waist of user. One of the main difficulties of using a single camera in outdoor obstacle detection is the discrimination of obstacles from a complex background. To solve this problem, this paper re-formulates top-view mapping as an inhomogeneous re-sampling process, so that background edges are sub-sampled while obstacle edges are oversampled in the top-view domain. Morphology filters are then used to enhance obstacle edges as edge-blobs, which are further represented using a directional ellipse as a new model for obstacle classification. Based on the identified obstacles, safe walking area is estimated by tracking a polar edge-blob histogram. To transfer the information obtained from image domain to language domain, this paper proposes a verbal message generation scheme based on fuzzy logic. The efficiency of the system is confirmed by testing the system with visually impaired people on outdoor pedestrian paths.

LORENTZ SELF-FORCE OF AN ELLIPSE CURRENT LOOP MODEL

In this work, the Lorentz self-force of an ellipse current loop model is derived. We are motivated by the fact that it has been reported in the literature that coronal mass ejection morphology can resemble an ellipse in the field of view of coronagraph images. Deriving the Lorentz self-force using an ellipse geometry has the advantage of being able to be solved analytically, as opposed to other more complex geometries. The derived ellipse model is compared with the local curvature approximation, where the Lorentz self-force at the ellipse major/minor axis is compared with the Lorentz self-force of a torus with curvature equal to the local curvature at the ellipses major/minor axis. It is found that the local curvature approximation is valid for moderate values of eccentricity.

Simulation studies of statistical distributions of cell membrane capacities and an ellipse model to assess the frequency behaviour of biological tissues

The frequency behaviour of biological tissues is commonly described by a Cole model reflecting a single-cell bio-impedance model extended with an exponent α. However, for this parameter α there is no physical or biological substrate, which impedes an interpretation. The present study confirms by computer simulations of tissue models that the factual frequency behaviour can be explained by assuming a distribution of the electrical impedance properties of cells and of the capacitive coupling between cells. This behaviour is modelled mathematically by an ellipse. A mathematical procedure is presented to estimate this ellipse from experimental data by a least square method. A model parameter β is introduced, representing the ratio of the axes of the ellipse. A higher value of β means a larger variation in cell properties, which makes a patho-physiological interpretation of changes possible.

Stochastic vehicle handling prediction using a polynomial chaos approach

One fundamental difficulty in understanding the physics of the off-road traction and in predicting vehicle performance is the indeterminacy of certain important parameters on the interface between tyre and terrain/road surface, for instance, the slip ratio, the slip angle, the normal forces, and the friction coefficients. It is not possible to accurately capture the effect of such uncertainties on the tyre behaviour (resultant force and moments) using a deterministic model. In addition, current measuring techniques have certain limitations and sometimes non-negligible measurement errors could be a source of relatively rough approximations in estimating some important parameters involved in vehicle dynamics simulations and control algorithms. In this study, mathematical tools to quantify the impact of uncertainties in tyre-terrain interface on vehicle handling were employed. We treated the uncertainty in key parameters associated with the tyre-road interface using a polynomial chaos approach. Two of the most popular semi-empirical models for predicting the pneumatic tyres performance under steady-state and transient conditions, the Friction Ellipse Model (FEM) and the Magic Formula Model (MFM), were selected to be extended from the deterministic to a stochastic workframe, to account for the uncertainties in the tyre-terrain friction coefficient, the slip ratio, the slip angle, and the normal forces in the contact patch. The modelling approach presented in this paper was able to capture the stochastic nature of parameters of interest and to predict the response of the system under those uncertainties, in an effort to provide a better understanding and a more realistic prediction of the tyre-terrain interaction than a deterministic formulation. To illustrate the application of the stochastic tyre-road models on vehicle dynamics, they were simulated in conjunction with a bicycle-car model.