Extrapolation Of Curve Research Articles

Investigation of the Curing Kinetics and Rheological Behavior of Multifunctional Epoxy Resin System

The curing reactivity and viscosity of AG-70 epoxy resin system with MNA as the curing agent and 2,4-EMI as the accelerator promoter were measured by using non-isothermal differential scanning calorimetry (DSC) and RS600 Rotational Rheometer, respectively. According to the DSC curves at different heating rates, the curing parameters such as the gelation temperature, the peak temperature and the treat temperature were obtained by using T-β curve extrapolation, the kinetic parameters of the curing reaction were determined by using Kissinger, Ozawa and Crane equation, including the apparent activation energy, the pre-exponential frequency and the curing reaction order. Then the kinetic model based on an nth order reaction equation was set up. The experimental data of the viscosity behavior were analyzed, and modified dual-Arrhenius viscosity model was established to predict the isothermal rheological behavior. The relationship between gel-time and temperature was also analyzed.

Endometrial thickness predicts endometrial hyperplasia in patients with polycystic ovary syndrome

Body mass index is predictive of sonographic endometrial stripe thickness, which in turn is predictive of endometrial hyperplasia in patients with polycystic ovary syndrome. For every 1-mm increase in endometrial stripe, the odds ratio of hyperplasia increased by 1.48 (95% confidence interval, 1.04-2.10).

TheN14(p,γ)O15reaction studied with a composite germanium detector

The rate of the carbon-nitrogen-oxygen (CNO) cycle of hydrogen burning is controlled by the 14N(p,gamma)15O reaction. The reaction proceeds by capture to the ground states and several excited states in O-15. In order to obtain a reliable extrapolation of the excitation curve to astrophysical energy, fits in the R-matrix framework are needed. In an energy range that sensitively tests such fits, new cross section data are reported here for the four major transitions in the 14N(p,gamma)15O reaction. The experiment has been performed at the Laboratory for Underground Nuclear Astrophysics (LUNA) 400 kV accelerator placed deep underground in the Gran Sasso facility in Italy. Using a composite germanium detector, summing corrections have been considerably reduced with respect to previous studies. The cross sections for capture to the ground state and to the 5181, 6172, and 6792 keV excited states in O-15 have been determined at 359, 380, and 399 keV beam energy. In addition, the branching ratios for the decay of the 278 keV resonance have been remeasured.

On the scaling law of the evolution of lap-shear strength with healing temperature at amorphous polymer−polymer interfaces and surface glass transition

The evolution of lap-shear strength (σ) with healing temperature Th at symmetric and asymmetric amorphous polymer−polymer interfaces formed of the samples with vitrified bulk has been investigated. It has been found that the square root of the lap-shear strength behaves with respect to healing temperature as σ1/2 ~ Th both at symmetric and asymmetric interfaces. Basing on this scaling law between σ and Th, the values of the surface glass transition temperature \( \left( {T_{\rm{g}}^{\rm{surface}}} \right) \) have been estimated for a number of amorphous polymers by the extrapolation of the experimental curves σ1/2 ~ Th for symmetric polymer−polymer interfaces and, in some cases, for asymmetric, both compatible and incompatible, polymer−polymer interfaces, to zero strength. A significant reduction in surface glass transition temperature \( T_{\rm{g}}^{\rm{surface}} \) with respect to the glass transition temperature of the polymer bulk \( \left( {T_{\rm{g}}^{\rm{bulk}}} \right) \), reported earlier, has been confirmed by the use of the new proposed approach. The quasi-equilibrium surface glass transition temperature \( T_{\rm{g}}^{\rm{surface}} \) of amorphous polystyrene (PS) has been predicted in the framework of an Arrhenius approach using the plot “logarithm of healing time − reciprocal surface glass transition temperature \( T_{\rm{g}}^{\rm{surface}}\prime \prime \) and the activation energy of the surface alpha-relaxation of PS has been calculated.

Extrapolating phosphorus production to estimate resource reserves

Various indicators of resource scarcity and methods for extrapolating resource availability are examined for phosphorus. These include resource lifetime, and trends in resource price, ore grade and discovery rates, and Hubbert curve extrapolation. Several of these indicate increasing scarcity of phosphate resources. Calculated resource lifetime is subject to a number of caveats such as unanticipated future changes in resource discovery, mining and beneficiation technology, population growth or per-capita demand. Thus it should be used only as a rough planning index or as a relative indicator of potential scarcity. This paper examines the uncertainty in one method for estimating available resources from historical production data. The confidence intervals for the parameters and predictions of the Hubbert curves are computed as they relate to the amount of information available. These show that Hubbert-type extrapolations are not robust for predicting the ultimately recoverable reserves or year of peak production of phosphate rock. Previous successes of the Hubbert curve are for cases in which there exist alternative resources, which is not the situation for phosphate. It is suggested that data other than historical production, such as population growth, identified resources and economic factors, should be included in making such forecasts.

Comparative RNA Quantification of HIV-1 Group M and Non-M With the Roche Cobas AmpliPrep/Cobas TaqMan HIV-1 v2.0 and Abbott Real-Time HIV-1 PCR Assays

A new version of the Roche Cobas AmpliPrep/Cobas TaqMan HIV-1 assay (CA/CTM v2.0) has been introduced to overcome the underquantification observed with the first version. We compared the Roche Cobas CA/CTM v2.0 and Abbott RealTime HIV-1 assays for HIV-1 group M and non-M viral load measurement. We found a good correlation (r = 0.96) between the 2 techniques for the 260 HIV-1 group M plasma samples tested. The Roche Cobas assay gave significantly higher values than the Abbott assay, and 51 samples (20%) yielded differences greater than 0.5 log10 copies per milliliter. Conversely, 2 samples were more than 0.5 log10 copies per milliliter higher with the Abbott assay than with the Roche Cobas assay. Among the 84 samples with undetectable viral load in the Abbott assay (detection limit 40 copies/mL), 17 (20%) were detectable with the CA/CTM v2.0 assay (detection limit 20 copies/mL), with values ranging from 41 to 897 copies per milliliter. Extrapolation of the Abbott curves led to 10/17 (59%) of these samples being quantifiable. HIV-1 groups O and P were similarly quantified by the two techniques. The results of the Roche Cobas CA/CTM v2.0 and Abbott RealTime HIV-1 assays correlate well. The new version of the CA/CTM assay shows improved sensitivity. Nevertheless, the 2 assays differ by more than 0.5 log₁₀ copies per milliliter for some samples.

A hydraulic study on the applicability of flood rating curves

Several hydrological studies have shown that river discharge records are affected by significant uncertainty. This uncertainty is expected to be very high for river flow data referred to flood events, when the stage–discharge rating curve is extrapolated far beyond the measurement range. This study examines the standard methodologies for the construction and extrapolation of rating curves to extreme flow depths and shows the need of proper approaches to reduce the uncertainty of flood discharge data. To this end, a comprehensive analysis is performed on a 16km reach of the River Po (Italy) where five hydraulic models (HEC-RAS) were built. The results of five topographical surveys conducted during the last 50 years are used as geometric input. The application demonstrates that hydraulically built stage–discharge curves for the five cases differ only for ordinary flows, so that a common rating curve for flood discharges can be derived. This result confirms the validity of statistical approaches to the estimation of the so-called ‘flood rating curve’, a unique stage–discharge curve based on data of contemporaneous annual maxima of stage and discharge values, which appears insensitive to marginal changes in river geometry.

Influence of Mg2+substitution on the magnetic and electrical properties of Li‐Zn ferrite thick films synthesized with PVA matrix

PurposeThe purpose of this paper is to investigate the effect of Mg2+substitution on the magnetic and electrical properties of Li0.35−x Mg2x Zn0.3 Fe2.35−xO4 thick films synthesized with polyvinyl alcohol (PVA) matrix.Design/methodology/approachThe nanoferrites Li0.35−x Mg2x Zn0.3 Fe2.35−xO4 (x=0, 0.07, 0.14, 0.21, 0.28 and 0.35) were synthesized by chemical technique using aqueous solution of PVA (the matrix) and thick films were fabricated by screen printing technique. The DC magnetic hysteresis measurements, AC magnetic susceptibility and DC electrical resistivity were measured as a function of temperature.FindingsThe lattice parameter of thick film Li0.35−x Mg2x Zn0.3 Fe2.35−xO4 (x=0, 0.07, 0.14, 0.21, 0.28 and 0.35) increases with the substitution of Mg2+ions for Li1+and Fe3+. The surface morphology of the thick films showed the grain size increasing with Mg2+substitution till x=0.21 and then decreasing for the higher concentrations of magnesium. The magnetic moment nB (μB) computed from the Ms obtained by extrapolation of the magnetization curve showed a gradual decrease with the composition till x=0.21, beyond which a sudden decrease was observed. The resistivity of the films at room temperature had variation with composition x, similar to that of magnetic moment. The activation energies ΔEF and ΔEP were found to vary with composition x of the ferrite system.Originality/valueThe paper reports, for the first time, the magnetic and electrical properties of fritless Li0.35−xMg2xZn0.3Fe2.35−xO4 thick films using PVA polymer matrix. Up to x=0.21 (Mg2+), grain size increases and Curie temperature decreases beyond which reverse effect takes place.

CT image construction of a totally deflated lung using deformable model extrapolation

A novel technique is proposed to construct CT image of a totally deflated lung from a free-breathing 4D-CT image sequence acquired preoperatively. Such a constructed CT image is very useful in performing tumor ablative procedures such as lung brachytherapy. Tumor ablative procedures are frequently performed while the lung is totally deflated. Deflating the lung during such procedures renders preoperative images ineffective for targeting the tumor. Furthermore, the problem cannot be solved using intraoperative ultrasound (U.S.) images because U.S. images are very sensitive to small residual amount of air remaining in the deflated lung. One possible solution to address these issues is to register high quality preoperative CT images of the deflated lung with their corresponding low quality intraoperative U.S. images. However, given that such preoperative images correspond to an inflated lung, such CT images need to be processed to construct CT images pertaining to the lung's deflated state. To obtain the CT images of deflated lung, we present a novel image construction technique using extrapolated deformable registration to predict the deformation the lung undergoes during full deflation. The proposed construction technique involves estimating the lung's air volume in each preoperative image automatically in order to track the respiration phase of each 4D-CT image throughout a respiratory cycle; i.e., the technique does not need any external marker to form a respiratory signal in the process of curve fitting and extrapolation. The extrapolated deformation field is then applied on a preoperative reference image in order to construct the totally deflated lung's CT image. The technique was evaluated experimentally using ex vivo porcine lung. The ex vivo lung experiments led to very encouraging results. In comparison with the CT image of the deflated lung we acquired for the purpose of validation, the constructed CT image was very similar. The intensity mean absolute difference between these two images was calculated to be at 1%. Tumor center as well as a number of anatomical fiducial markers were traced in different corresponding slices of the two images. The average misalignment obtained for the constructed CT image was (0.64, 0.39, 0.11) mm, which indicates a very desirable accuracy for lung brachytherapy applications. The image construction accuracy obtained in this research is suitable for intraoperative tasks; e.g., tumor localization and fusing with real time navigation data in lung brachytherapy. These applications involve image registration with intraoperative U.S. images in order to enhance their poor quality. The proposed technique is also useful for preoperative tasks such as planning of lung brachytherapy treatment.

Experimental study of the [formula omitted] reaction at high and low energies

The 14 N ( p , γ ) 15 O reaction controls the rate of the carbon–nitrogen–oxygen (CNO) cycle of stellar hydrogen burning. The reaction proceeds by capture to the ground state and several excited states in 15 O . Several studies of this reaction have recently been performed in the low energy range 150 < E p < 500 keV and only one set of data from an experiment performed in 1987 extends up to 3 MeV. In order to obtain a reliable extrapolation of the excitation curve to astrophysical energy, R-matrix fits need data covering the widest possible range of energy. In a first phase, the experimental investigation has been performed at the Laboratory for Underground Nuclear Astrophysics (LUNA) 400 kV accelerator in an energy range that sensitively tests such fits, placed deep underground in the Gran Sasso facility in Italy, using a composite germanium detector. In a second phase, the reaction has been studied at the high-current FZD Tandetron in Dresden (Germany), in the energy region from 0.6 to 2.5 MeV. The astrophysical motivation, setup, and data analysis are presented.

Prediction by the human visual system: Extrapolation of complex curves

Prediction by the human visual system: Extrapolation of complex curves

Extrapolation of rating curves by hydraulic modelling, with application to flood frequency analysis

This paper illustrates the importance of taking into account the potential errors in discharge estimation in the assessment of extreme floods. First, a summary of the main difficulties encountered in extrapolating rating curves for flood discharge is provided. Then a sensitivity analysis is carried out using a hydraulic modelling approach, applied to eight Mediterranean catchments, and yielding an envelope curve for the stage–discharge relationship, Q(H). To assess the influence of errors in the flood discharge on the uncertainty in estimating extreme floods, a Bayesian framework including a multiplicative error on the rating curve was applied. Its application on two catchments for which historical data are available for the period (1741–2004) shows that ignoring the rating curve errors may lead to an unduly optimistic reduction in the final uncertainty in estimation of flood discharge quantiles. Moreover, the quantile values are also affected by taking into account the rating curve errors. Citation Lang, M., Pobanz, K., Renard, B., Renouf, E. & Sauquet, E. (2010) Extrapolation of rating curves by hydraulic modelling, with application to flood frequency analysis. Hydrol. Sci. J. 55(6), 883–898.

Paleohydrologic bounds and extreme flood frequency of the Upper Arkansas River, Colorado, USA

The Upper Arkansas River basin has experienced notable large floods, including the event of 2–6 June 1921 that devastated the city of Pueblo, Colorado. We investigated flood and paleoflood hydrology at strategic sites to determine the frequency and geographic extent of extreme floods within the basin for a dam safety application. Streamgage, historical, and paleoflood data were utilized to develop frequency curves at sites near Salida, Cotopaxi, Parkdale, and Pueblo. Soil/stratigraphic descriptions, radiocarbon dating, and hydraulic modeling were used to estimate paleoflood nonexceedance bounds at the four sites, which ranged from 400 to 2200 YBP for late Holocene surfaces to late Pleistocene surfaces near Cotopaxi. Peak-flow data are from lower-magnitude snowmelt runoff in May and June in the upper basin and from high-magnitude rainfall runoff from June to August in the lower basin. Flood frequency curves reflect this transition near Parkdale from snowmelt to extreme rainfall-runoff. For similar return periods, paleoflood peak discharges increase from about 480 m 3/s upstream at Loma Linda to about 4250 m 3/s downstream near Pueblo. This increase is attributed to the larger rainfall component derived from lower elevations between Loma Linda and Pueblo. Return periods for design floods at Pueblo Dam exceeded 10,000 years based on paleoflood frequency curve extrapolations.

Metamodel predictions for long range speech intelligibility using parabolic equation calculations.

The Crank–Nicholson parabolic equation (CNPE) method was used to calculate speech intelligibility for long range propagation of voice messages. How intelligible a voice message will be at long range is very sensitive to atmospheric conditions and parameters such as source height and background noise levels. In order to identify this sensitivity, four independent variables were identified and varied throughout the study. These independent variables are the atmospheric refraction index, which takes into account both temperature and wind gradients within the atmosphere, ambient temperature, source height, and background noise level. CNPE computations were performed for 31 optimally chosen cases where all four of the independent variables were random variables and were inputted into a metamodel. This allows for curve fitting and extrapolation of the existing data to determine intermediate results for any operation scenario defined within the bounds of the current study. Upon doing this, it was determined that the atmospheric refraction index is the most sensitive variable. In addition, there is virtually no dependence on ambient surface temperature.

Curve Extrapolation and Data Analysis Using the Method of Hurwitz-Radon Matrices

Curve Extrapolation and Data Analysis Using the Method of Hurwitz-Radon MatricesData analysis needs suitable methods of curve extrapolation. The proposed method of Hurwitz-Radon Matrices (MHR) can be used in extrapolation and interpolation of curves in the plane. For example, quotations from the Stock Exchange, the market prices or currency rates form a curve. This paper presents the way of data anticipation and extrapolation via the MHR method and decision making: to buy or not, to sell or not. The proposed method is based on a family of Hurwitz-Radon (HR) matrices. The matrices are skew-symmetric and possess columns composed of orthogonal vectors. The operator of Hurwitz-Radon (OHR), built from these matrices, is described. Two-dimensional data are represented by the set of curve points. It is shown how to create the orthogonal and discrete OHR and how to use it in a process of data foreseeing and extrapolation. The MHR method interpolates and extrapolates the curve point by point without using any formula or function.

Monte Carlo simulation to positron emitter standardized by means of 4πβ-γ coincidence system—Application to 22Na

The present work describes the methodology for predicting the behavior of extrapolation curves obtained in radionuclide standardization by 4pibeta-gamma coincidence measurements, applied to (22)Na, developed at the Laboratório de Metrologia Nuclear of IPEN-CNEN/SP (LMN-Nuclear Metrology Laboratory). The LMN system consists of a proportional counter (PC) in 4pi geometry coupled to a single or a pair of NaI(Tl) scintillation crystals. Two standardization techniques were used: the Sum-Peak and the Nuclear-Peak methods. The theoretical response functions of each detector have been calculated using the MCNPX Monte Carlo code. The code ESQUEMA, developed at LMN, has been used for calculating the extrapolation curve in the 4pibeta-gamma coincidence experiment. Modifications were performed in order to include response tables for positrons and coincidences with annihilation photons. From the calibration results it was possible to extract both the activity value and the positron emission probability per decay. The latter was compared with results from the literature.

Standardisation of 124SB and 152EU using software coincidence counting system

Activities of the radionuclides (124)Sb and (152)Eu were determined by the efficiency extrapolation method applied to 4pi(PC)-gamma coincidence counting. The (124)Sb sources were prepared from a solution with the chemical form of 50 microg g(-1) SbCl(3) in 2 M HCl. To inhibit the volatility of antimony chlorides, the sources were slowly dried in a H(2)S atmosphere with relative humidity of 76% for about 48 h. This procedure increased the beta detection efficiency up to 0.98, which simplified the standardisation. In the (152)Eu standardisation, the optimal gamma-ray energy window setting to achieve a linear dependency and the correct slope of the extrapolation curve were derived by means of software coincidence counting system using offline evaluation of data with different coincidence parameter settings. The results obtained by the software coincidence counting system were compared with those obtained by the conventional coincidence method.

Standardization and measurement of gamma-ray probability per decay of 177Lu

The procedure followed by the Nuclear Metrology Laboratory (LMN), at the Nuclear and Energy Research Institute (IPEN), for the primary standardization of (177)Lu is described. This radionuclide is widely used in radiopharmacy due to its convenient half-life and emitted beta ray energies. The (177)Lu solution was supplied during an international comparison sponsored by BIPM in 2009 and the primary standardization has been accomplished by the 4pibeta-gamma coincidence method using a proportional counter in 4pi geometry coupled with two NaI(Tl) scintillation counters. The beta efficiency was varied by placing Collodion and aluminum absorbers over and under the radioactive source. The (177)Lu calibrated sources were also measured in a previously calibrated HPGe spectrometer, in order to obtain the emission probability per decay for the selected gamma-ray transitions. The experimental extrapolation curves were also compared with Monte Carlo simulations by means of code ESQUEMA developed at the LMN.

Determination of 198Au X-rays emission probabilities

This work describes the measurements of the K X-ray and gamma-ray emission probabilities per decay of (198)Au performed at the Nuclear Metrology Laboratory (LMN) at the IPEN, São Paulo. The radioactive sample was obtained by means of (197)Au(n, gamma)(198)Au reaction irradiating an Au foil in a thermal neutron flux near the core of the IPEN 3.5 MW research reactor. The activity of samples was determined in a 4pibeta-gamma coincidence system, setting the gamma window at the 411.80 keV total energy absorption peak. The same samples were measured in two different spectrometers: a HPGe planar spectrometer with Be window, suitable for measurements in the low energy range and a coaxial REGe spectrometer. Both spectrometers were previously calibrated in a well defined geometry by means of standard sources calibrated in a 4pibeta-gamma coincidence system. MCNP4C Monte Carlo code was used for simulating the REGe spectrometer calibration curve, and a new version of code ESQUEMA was adopted for simulating the detection processes in the coincidence system, in order to predict the efficiency extrapolation curve.

Primary standardization of 57Co

This work describes the method developed by the Nuclear Metrology Laboratory in IPEN, São Paulo, Brazil, for the standardization of a (57)Co radioactive solution. Cobalt-57 is a radionuclide used for calibrating gamma-ray and X-ray spectrometers, as well as a gamma reference source for dose calibrators used in nuclear medicine services. Two 4pibeta-gamma coincidence systems were used to perform the standardization, the first used a 4pi(PC) counter coupled to a pair of 76 mm x 76 mm NaI(Tl) scintillators for detecting gamma-rays, the other one used a HPGe spectrometer for gamma detection. The measurements were performed by selecting a gamma-ray window comprising the (122 keV+136 keV) total absorption energy peaks in the NaI(Tl) and selecting the total absorption peak of 122 keV in the germanium detector. The electronic system used the TAC method developed at LMN for registering the observed events. The methodology recently developed by the LMN for simulating all detection processes in a 4pibeta-gamma coincidence system, by means of the Monte Carlo technique, was applied and the behavior of extrapolation curve compared to experimental data. The final activity obtained by the Monte Carlo calculation agrees with the experimental results within the experimental uncertainty.