Post-processing Results Research Articles

The ultraconvergence of derivative for bicubic finite element

It is for the first time that we obtained the O ( h 6 ) convergence of the derivatives for bicubic finite element by a new recovery technique proposed in Meng and Zhu [L.X. Meng, Q.D. Zhu, The ultraconvergence derivative recovery technique for odd-degree elements – a computer-based test result, Natur. Sci. J. 25 (2) (2003) 117–121]. This numerical postprocessing result is theoretically justified by using projection interpolant and the theory of discrete Green’s function in this paper.

PLOTREP: a web tool for defragmentation and visual analysis of dispersed genomic repeats

Identification of dispersed or interspersed repeats, most of which are derived from transposons, retrotransposons or retrovirus-like elements, is an important step in genome annotation. Software tools that compare genomic sequences with precompiled repeat reference libraries using sensitive similarity-based methods provide reliable means of finding the positions of fragments homologous to known repeats. However, their output is often incomplete and fragmented owing to the mutations (nucleotide substitutions, deletions or insertions) that can result in considerable divergence from the reference sequence. Merging these fragments to identify the whole region that represents an ancient copy of a mobile element is challenging, particularly if the element is large and suffered multiple deletions or insertions. Here we report PLOTREP, a tool designed to post-process results obtained by sequence similarity search and merge fragments belonging to the same copy of a repeat. The software allows rapid visual inspection of the results using a dot-plot like graphical output. The web implementation of PLOTREP is available at .

On the use of the Theory of Critical Distances and the Modified Wöhler Curve Method to estimate fretting fatigue strength of cylindrical contacts

This paper summarises an attempt to propose a methodology suitable for estimating high-cycle fatigue strength of cylindrical contacts under a partial slip regime. In particular, Taylor’s point method, usually applied to predict fatigue limits of notched components, was used in conjunction with the Modified Wöhler Curve Method allowing us to formulate a novel fretting fatigue prediction methodology. The devised procedure takes as its starting point the idea that to correctly estimate fatigue damage under fretting fatigue two different aspects must be taken into account: stress gradients and degree of multiaxiality of the stress field damaging the fatigue process zone. The first problem was addressed by using the Theory of Critical Distances, whereas the latter by using an appropriate multiaxial fatigue criterion. In order to check the accuracy of the proposed methodology, a number of tests on cylindrical contacts were selected from the technical literature for two high strength alloys commonly used in the aerospace industry, namely Al4%Cu and Ti–6Al–4V. The performed analyses showed a sound agreement between estimations and experimental data. In particular, the proposed method correctly predicted failures in the medium-cycle fatigue regime, allowing the high-cycle fatigue estimations to fall within an error interval of about ±20%. This result is very interesting, especially by the light of the fact that such an approach is based on the use of linear-elastic stresses, making it suitable for being used in situations of practical interest by post-processing linear-elastic finite element results.

On the use of the modified Wöhler Curve Method to estimate notch fatigue limits*

Abstract This paper takes a closer look at the use of the Modified Wöhler Curve Method (re-interpreted in terms of the Theory of Critical Distances) to predict the high-cycle fatigue strength of notched components subjected to fatigue loading. This method takes as its starting point the assumption that fatigue damage depends on all the physical phenomena taking place within the fatigue process zone (the so-called structural volume). The material volume controlling all the fatigue processes has a size which does not depend on the degree of multiaxiality of the stress field damaging critical sites, but its size is different for different materials. Assuming that crack initiation in the high-cycle fatigue regime is Mode II governed, the Modified Wöhler Curve Method must be applied by considering the linear-elastic stress state at the centre of the structural volume. The main advantage of this method is that it is based on the use of linear-elastic stresses: this aspect makes it suitable for being used to post-processing results from linear-elastic Finite-Element models. Finally, accuracy and reliability of the proposed method was checked by using data taken from technical literature: the Modified Wöhler Curve Method proved to be a useful tool for assessing mechanical components in situations of practical interest.

Local and structural multiaxial stress states in weldedjoints under fatigue loading

A cylindrical stiffener on a plate and a tube through a hollowed plate, both circularly welded, were tested under uniaxial fatigue loading. Their fatigue cracking behaviour was seen to be really complex due to the fact that crack initiation sites changed their position as the number of cycles to failure increased. To investigate this anomalous behaviour, an accurate numerical investigation was carried out to study the distribution of both local and structural linear elastic stresses along the weld toe circumferences. The numerical results proved that the weld beads were subjected to complex stress states, even though the applied nominal load was uniaxial. By the light of this evidence, the fatigue behaviour of the investigated welded joints was then re-interpreted from a multiaxial fatigue point of view by applying the Modified Wöhler Curve Method in terms of hot-spot stresses. The proposed approach was seen to be successful allowing us to estimate both crack initiation sites and fatigue lifetime with a high precision level. This fact is very interesting because it strongly supports the idea that our method can be used to assess real welded components subjected to multiaxial fatigue loading by simply post-processing linear-elastic finite-element results.

Quantum transport in ultra-scaled double-gate MOSFETs: A Wigner function-based Monte Carlo approach

Source-to-drain current including tunneling in deca-nanometer double-gate MOSFETs is studied using a Monte Carlo approach for the Wigner transport equation. This approach allows the effect of scattering to be included. The subband structure is calculated by means of post-processing results from the device simulator Minimos-NT, and the contribution of the lowest subband is determined by the quantum transport simulation. Intersubband coupling elements are explicitly calculated and proven to be small in double-gate MOSFETs. The simulation results clearly show an increasing tunneling component of the drain current with decreasing gate length. For long gate length the semi-classical result is recovered.

Forecasting wave height probabilities with numerical weather prediction models

Operational weather forecasts now allow two week probabilistic forecasts of wave height. This paper discusses methods for generating such forecasts from numerical model output from the European Centre for Medium Range Weather Forecasting Ensemble Prediction System. The ECMWF system produces Monte Carlo style forecasts of wave statistics out to a lead time of 10 days. This ensemble of forecasts is designed to reflect uncertainty in current global weather conditions. In this paper a method for post-processing the ensemble forecasts of wave statistics is described and demonstrated using the significant wave height forecasts for four locations of interest to the offshore industry. The post-processing results in ensemble forecasts which have improved reliability, and which are better predictors of the expected error in the forecast.

Wigner Function-Based Simulation of Quantum Transport in Scaled DG-MOSFETs Using a Monte Carlo Method

Source-to-drain tunneling in deca-nanometer double-gate MOSFETs is studied using a Monte Carlo solver for the Wigner transport equation. This approach allows the effect of scattering to be included. The subband structure is calculated by means of post-processing results from the device simulator Minimos-NT, and the contribution of the lowest subband is determined by the quantum transport simulation. By separating the potential profile into a smooth classical component and a rapidly varying quantum component the numerical stability of the Monte Carlo method is improved. The results clearly show an increasing tunneling component of the drain current with decreasing gate length. For longer gate lengths the semi-classical result is approached.

MDCT-imaging of peripheral arterial disease

With the design and development of advanced computed tomography (CT) techniques and applications, like the newest generation of 16-detector-row CTs, CT angiography of the lower limb becomes a feasible tool for imaging peripheral vascular disease. Due to several advantages, compared with conventional digital subtraction angiography (DSA), including minimal invasiveness, CT angiography competes against diagnostic DSA in several clinical situations. 16-DCT offers the possibility to acquire thin slices from the diaphragm to the ankle in less than 40 sec. Easily, a data set of 800 to 1200 transverse slices may be created. To use transverse reconstructions alone to read these volumetric data sets is not appropriate. Powerful post-processing tools for volumetric analysis are required so that routine interpretation can be performed as efficiently and accurately as transverse section review. Because of its widespread availability and applicability, CT angiography of the lower extremities may be applied to patients in a pre- or post-procedural situation and also serves as a first line modality in patients with acute onset of clinical symptoms. Although multidetector CT arteriography is rapidly achieving clinical acceptance, further studies need to be performed to fully evaluate the clinical value of this method of peripheral arterial imaging. This article reviews the current status of multidetector CT peripheral arteriography, including indications, technical details, image post-processing, radiation exposure, and clinical results.

Software components retrieval through mediators and web search

Component Based Development (CBD) aims at constructing software through the integration, using interfaces and contracts, between pre-existing components. The main goal of this work is to provide access to component that can be published at the Web, retrieved, and reused in all phases of an application development within a given domain. We present an architecture for software components reuse by using a mediation layer that integrates the semantics of Web components with previously registered components from a virtual library of components. In our architecture, components are described through XML documents and published by local repositories or remote servers. The innovative aspect of our proposal is the combination of mediators and software agents for reusable component retrieval within a Domain Engineering context. Mediators can represent application domain as well as integrate the description of domain related components. Queries can be issued to the mediation layer and processed by the GOA Object Server, which presents the query results as a list of suggested components along with its repository link in XML. Software agents are responsible for web component discovery and filtering. Techniques such as user models (profiles), and recommendations are used for presenting a ranked list of links. Finally, resulting links from mediators and web post-processed results are combined and presented to the user.

The sperm-recovering efficiency (SRE), a method to quantify the efficiency of sperm preparation techniques

Objective: To propose the SRE, an equation that includes concentration, motility, morphology and final sperm percentage to determine and compare the efficiency of Sperm Preparation Techniques (SPT). Design: A theoretical and deductive analysis. Materials/Methods: None. Results: One important step in ART is the processing of sperm samples to separate motile progressive (A and B) and morphologically normal sperms from seminal plasma and other undesired components. The different SPT search for a final high motile progressive (MP) and morphologically normal (MN) sperm concentration. We propose to integrate these parameters in an equation, SRE, to produce a unique # to compare these results. The equation is: SRE = SRI x FSF, where SRI is the Sperm Recovering Index and FSF is the Final Sperm Fraction. Thus, the efficiency of a SPT is given for the final concentration of MP and MN sperms (SRI) and the % of these sperms in the final sample (FSF). Consider the terms showed in the table, thus, the SRI is given for [CfxVfx(%A+%B)fx%Nf]/[CixVpx(%A+%B)ix%Ni]. The result is a # between 0 and 1. 0 represents a SPT with no MP and MN sperms recovered in the final sample and 1 represent a final sample in which all MP and MN sperms are recovered. The FSF is determined as a relation between the final concentration of MP and MN sperms regarding to the final sperm concentration as [CfxVfx(%A+%B)fx%Nf]/[Cf xVf]. The result is a # between 0 and 1, where 1 means that the final sample is constituted 100% for MP and MN sperms, and 0 means that this final sample does not have any MP and MN sperm. Thus SRE = FSF x SRI represent the components for a complete sample evaluation after SPT. The maximum value for SRE is 1, which means that the SPT recovered the whole MP and MN sperms present in the initial sample and these sperms represent the whole final sperm population. The minimum value for SRE is 0, which means that the SPT recovers no MP or MN sperm. Exist a threshold value, the SRE-basal that is a minimum value expected after any processing technique. The SREb = SRIbxFSFb = {[Ci x Vi x (%A+%B) i x %Ni]/[Ci x Vi x (%A+%B) i x %Ni]} x {[Ci x Vi x (%A+%B)ix %Ni/Ci x Vi]}. The initial and final values for all terms of this equation are the same, because we expect to have after the SPT at least the same sperms found in the initial sample. Thus SRIb is 1 and FSFb acquires a value that is particular for each sample and depends of its initial parameters. Values of SRE below the SRIb means that the SPT made worse the sample respect to the initial one, in terms of MP and MN sperm concentration and/or final sperm proportion. Values above the SREb means an improvement respect to the initial values. There exists a Delta-SRE (ΔSRE) = SRE-SREb, which represents a variation regarding to the basal value and permits a quantification of post-processing result indicating how much the sample changed respect to the basal value. Tabled 1TermsDescriptionCiinitial sperm concentrationVpvolume of sample prepared(%A + %B)iinitial % of sperms A and B%Niinitial % of MN spermsCffinal sperm concentrationVffinal sperm volume(%A + %B)ffinal % of sperms A and B%Nffinal normal sperm % Open table in a new tab Conclusions: The SRE is a useful measure to quantify the sperm processing techniques results, which could make more feasible its interpretation and analysis, generating a better comprehension of the process entailed in the SPT and promoting the development of better technique and mediums with this purpose. Supported by: None.

Multi parametric assay for detection of the cause for increased radiation sensitivity in 15 different lymphoblastoid cell lines

Purpose: Excessive radiation sensitivity (RS) may be the result of misrepair or incomplete post repair processing in the different repair steps. It seems therefore unlikely that one single test should be able to detect all individuals with increased RS. The purpose of this study was to investigate 15 patient derived cell lines by 4 different tests in order to identify typical patterns associated with the various causes of increased RS. The 4 tests should examine defects in important mechanisms for the development of elevated radiosensitivity, therefore the tests were applied to analyze DNA-dsb-repair, apoptosis, cell cycle control and chromosomal aberrations.

Towards an operational near real-time precipitable water vapor estimation

We are presenting the results of a stable procedure for near real-time (NRT) processing developed at the analysis center of Geodetic Observatory Pecný (AC GOP). The procedure was tested routinely during more than one year. The GOP NRT tropospheric products based on 48 h predicted orbits are available two hours later after the last measured data. Since the estimated accuracy for precipitable water vapor is 1 mm, this product can be considered as the support for a numerical weather prediction. In addition, the post-processed results (Post), based on the rapid orbits, were produced with the delay of two days. Results of different strategies are presented, NRT solutions compared to the post-processed solutions and both are validated by radiosonde data.

Near real-time water vapor estimation in a German GPS network-first results from the ground program of the HGF GASP project

For the ground-based part of the GPS Atmosphere Sounding Project (GASP) the near real-time monitoring of integrated water vapor with a delay of 1.5 hours was demonstrated for 35 sites and the data retrieval for 46 sites is already in progress. Comparisons to post-processed results as well as validation with independent techniques and models show that an accuracy of 1–2 mm in the precipitable water vapor could be achieved. To make this possible also software for Ultra Rapid orbit predictions (10–20 cm accuracy) and interpolation within surface meteorological data from synoptic networks (0.3hPa accuracy) were developed.

Extraction of welds from radiographic images using fuzzy classifiers

This paper presents a methodology for extracting welds (linear or curved) from digitized radiographic images. The methodology consists of three major steps: feature extraction, pattern classification, and post-processing. Each weld image is processed line by line to extract three features for each object in the line image. These features are the width, the mean square error (MSE) between the object and its Gaussian, and the peak intensity (gray level). The fuzzy K-NN and fuzzy c-means algorithms are used as the pattern classifiers to recognize each object as weld or non-weld. Their performances are compared. The post-processing operation is applied to remove noises generated due to false alarms and to connect discontinuous weld lines due to misclassifications. The difficulties involved in post-processing results obtained by the fuzzy K-NN and fuzzy c-means algorithms are discussed. It is shown that both classifiers can successfully extract welds. However, the fuzzy K-NN classifier is concluded to be better because it gives fewer false alarms, and thus easier weld extraction.

Internal structure of flux transfer events produced by the onset of merging at a single X line

We present a new, higher‐order, two‐dimensional, magnetohydrodynamic model for the detailed internal structure of bubbles produced by the onset of merging along a single subsolar X line. The key feature of the model is to implement a nonlinear filter to postprocess results provided by the pseudospectral element method. The devised nonlinear filter (1) eliminates only the high‐frequency oscillations, (2) retains conservation laws, and (3) enforces a total variation diminished criterion to guarantee the elimination of spurious oscillations near discontinuities. For realistic parameters, the model predicts that satellites which remain in the magnetosheath will observe asymmetric bipolar magnetic field signatures normal to the magnetopause, magnetic field strength increases, density and temperature decreases, and velocities opposite the motion of the events. Satellites in the magnetosheath which enter the events observe asymmetric bipolar signatures normal to the magnetopause, magnetic field strength decreases, densities intermediate between those in the magnetosheath and magneto‐sphere, temperature increases, and velocities in the direction of event motion. Satellites initially located just outside the the magnetopause observe greatly depressed densities and enhanced temperatures (but no significant bipolar signatures normal to the magnetopause) followed by velocity jets of magnetosheath‐like plasma on northward magnetospheric magnetic field lines. Satellites in the magnetosphere which enter the events observe depressed magnetic field strengths, enhanced densities and temperatures, and accelerated flows surrounding a core region of accelerated magnetosheath‐like plasma. Neither they nor satellites which remain in the magnetosphere observe any significant bipolar signatures normal to the nominal magnetopause.

Intelligent Process Monitoring of Multilayer Ceramic Actuators Using High Temperature Optical Fiber Displacement Sensors

The Fiber & Electro-Optics Research Center (FEORC) has developed a sensing technique for the intelligent processing of a multilayer ceramic actuator (MCA) elements manufactured by the AVX Corporation in Conway, South Carolina. Presented are the results of the fiber optic strain sensor used to monitor the burnout of organic binders from a green actuator sam ple. The results establish the operation of the short gage length, low finesse Fabry-Perot interferometric strain sensor as a tool for intelligent processing of such ceramic actuator elements. Also pre sented is the method of sensor operation, and post-processing results using the same sensor for tracking actuator performance and hysteresis.

Direct 75 milliarcsecond images from the Multiple Mirror Telescope with adaptive optics

We report results from an adaptive optics system designed to provide imaging at the diffraction limit of resolution in the near-infrared at the Multiple Mirror Telescope (MMT). For the present experiment, the aperture consisted of five of the six primary mirrors of the MMT, operating as a coherently phased array. The largest components of the atmospherically induced wave-front aberration are the fluctuations in mean phase between the segments. These errors were derived in real time from the Fourier transform of short-exposure stellar images at 2.2 microns and corrected at an image of the telescope pupil with piston motion from a segmented adaptive mirror. At a correction rate of 43 Hz, this level of adaptive control resulted in an integrated image with a clear diffraction-limited component of 0.075 arcsec FWHM. This stabilized component is present directly in the light arriving at the detector and is not the result of postprocessing. We discuss future improvements to our adaptive wave-front control and its application to astronomical observations.

Machaerocereus eruca cactus isolectins. Purification and characterization

Four isolectins from the cactus Machaerocereus eruca (ME-C2, D2,E2,F2) have been isolated and purified by hydrophobic and affinity chromatography on a red blood cell stroma column; in their native form there were differences in the molecular weights, whereas in their monomeric form they all showed a repetitive subunit of 35 kDa. The glycan portion of the isolectin which is composed of glucose, galactose, rhamnose, xylose and mannose, represented 20, 24, 26 and 30% of their weight, for ME-C2, D2, E2 and F2, respectively. All four isolectins were closely related in amino acid composition, although the less hydrophobic isolectin contained more glycine and threonine than the more hydrophobic fraction. Hapten inhibition assays indicated that the isolectins possess specificity for d-galactose, N- acetyl- d-galactosamine and galactose-containing glycoproteins and glycopeptides. All the isolectins were capable of suppressing the murine humoral immune response to particulated antigens, although no mitogenic activity in murine lymphocytes was found. The differences found in their physicochemical properties, glycan portion, ability to bind to a hydrophobic gel and amino acid composition suggest that either they are the products ofrelated but distinct genes or the result of different post translational protein processing.