Order Polynomial Fit Research Articles

An approach for on-line signature authentication using Zernike moments

In this work, shape analysis of the acceleration plot, using lower order Zernike moments is performed for authentication of on-line signature. The on-line signature uses time functions of the signing process. The lower order Zernike moments represent the global shape of a pattern. The derived feature, acceleration vector is computed for the sample signature which comprises on-line pixels. The Zernike moment represent the shape of the acceleration plot. The summation value of a Zernike moment for a signature sample is obtained on normalized acceleration values. This type of substantiation decreases the influence of primary features with respect to translation, scaling and rotation at preprocessing stage. Zernike moments provide rotation invariance. In this investigation it was evident that the summation of magnitude of a Zernike moment for a genuine sample was less as compared to the summation of magnitude of a imposter sample. The number of derivatives of acceleration feature depends on the structural complexity of the signature sample. The computation of best order by polynomial fitting and reference template of a subject is discussed. The higher order derivatives of acceleration feature are considered. Signatures with higher order polynomial fitting and complex structure require higher order derivatives of acceleration. Each derivative better represents a portion of signature. The best result obtained is 4% of False Rejection Rate [FRR] and 2% of False Acceptance Rate [FAR].

DYNAMIC RECRYSTALLIZATION AND PRECIPITATION BEHAVIORS OF A KIND OF LOW CARBON V–MICROALLYED STEEL

By using thermo-mechanical simulator,OM and TEM,the dynamic recrystallization (DRX) and precipitation behaviors of a kind of low carbon V-microalloyed steel have been investigated at temperatures ranging from 900 to 1050℃and strain rates from 0.01 to 10 s~(-1).The activation energy (Qdef) for hot deformation of this kind of V-microalloyed steel was calculated to be 341.97 kJ/mol by regression analysis,while the apparent stress exponent(n) was calculated to be 4.24.The equation describing the hot working process was also obtained.The critical strain for DRX was accurately determined based on the P-J method and high order polynomial fitting between strain hardening rate and true stress,and mathematical models of critical strain and peak strain versus Z parameter were deduced.The dynamic precipitation behavior of V(C,N) particles at low strain rate was further investigated.The results show that with increasing the strain,the average size of V(C,N) particles increases and the size distribution of the precipitates become wide.The calculations of the driving force for recrystallization and pinning force show that once the dynamic recrystallization take place, the dynamic precipitation could not prevent dynamic recrystallization from occurring.

Calculation of transport cross sections for positrons in solid targets via improved expressions

Transport cross sections (TCS) for positron impinging on a number of selected atomic targets have been calculated in the energy range 1–4 keV. The calculations were performed by using a simplified correction of the approximate analytical expression of transport cross sections reported by Jablonski [A. Jablonski, Phys. Rev. B 58 (1998) 16470]. An argued parameter–obtained from both an exponential and polynomial fits–was then introduced. The agreement generally observed between our results and those previously reported in the literature is quite good, especially for positron energies greater than 2 keV. Furthermore, an attempt has been made for scaling the TCS with the atomic number of solid targets of interest. Such a scaling was found to be possible for both exponential and third order polynomial fits. The information gathered by the present study may be useful for the evaluation of parameters needed for quantitative low-energy positron annihilation spectroscopy.

New polynomial approach to myriad filter computation

The myriad filter is a robust filter which is very useful in suppressing impulsive noise. It belongs to the family of robust M-filters and is controlled with one parameter only. The myriad filter is defined as a running window filter whose output is the sample myriad of the elements in the window. The most popular approach to determination of myriad filter output is based on the fixed point method. However, in this case time of computation is relatively long, which limits on-line applications. In this paper, a faster method of the myriad filter computation is presented. It performs the second order polynomial fitting and the next x-coordinate of the parabola top is searched. The proposed method can operate on different types of impulsive noise, requires less computational time and is equally robust as the fixed point method or the branch-and-bound search method. The presented method is applied to process a chirp signal in impulsive environment. The obtained results are compared to the fixed-point algorithm and the branch-and-bound searching method.

Effect of Different Parameters on Clarification Efficiency of Mechanical Clarifier

Effects of parameters namely, height of agitator from lid (15, 16, 17 cm.), centrifugation speed (2500, 3000, 3500 RPM) and time of centrifugation (5, 10, 15 min.) on mechanical clarification of sugarcane juice were studied. Filtration was incorporated as a pretreatment which reduced the amount of impurities in the juice. Soluble solids, total solids, sediment obtained, optical density and percent transmittance were measured and used for determining the efficacy of mechanical clarification of sugarcane juice. Full factorial design was used for selecting the levels of parameters in the experiment. Full second order polynomial and best fit equations were developed to predict various responses and to study individual, square and interactive effects of parameters on the responses. The clarification efficiency ranged between 11.3-42.2% and Optical density varied between 1.52 and 0.92 for mechanical clarification of sugarcane juice. Minimum percent transmittance was 3 and maximum was 13. Minimum sediment per 20 ml. of juice due to centrifugal force was 0.989 g. and maximum was 2.358 g. for mechanical clarification. Centrifugation time had highly significant effect on clarification efficiency followed by centrifugation speed, and height of agitator in that order. However, centrifugation speed had significant effect on optical density and percent transmittance.

Long-term MST radar observations of vertical wave number spectra of gravity waves in the tropical troposphere over Gadanki (13.5° N, 79.2° E): comparison with model spectra

Abstract. The potential utility of Mesosphere-Stratosphere-Troposphere (MST) radar measurements of zonal, meridional and vertical winds for divulging the gravity wave vertical wave number spectra is discussed. The data collected during the years 1995–2004 are used to obtain the mean vertical wave number spectra of gravity wave kinetic energy in the tropical troposphere over Gadanki (13.5° N, 79.2° E). First, the climatology of 3-dimensional wind components is developed using ten years of radar observations, for the first time, over this latitude. This climatology brought out the salient features of background tropospheric winds over Gadanki. Further, using the second order polynomial fit as background, the day-to-day wind anomalies are estimated. These wind anomalies in the 4–14 km height regions are used to estimate the profiles of zonal, meridional and vertical kinetic energy per unit mass, which are then used to estimate the height profile of total kinetic energy. Finally, the height profiles of total kinetic energy are subjected to Fourier analysis to obtain the monthly mean vertical wave number spectra of gravity wave kinetic energy. The monthly mean vertical wave number spectra are then compared with a saturation spectrum predicted by gravity wave saturation theory. A slope of 5/3 is used for the model gravity wave spectrum estimation. In general, the agreement is good during all the months. However, it is noticed that the model spectrum overestimates the PSD at lower vertical wave numbers and underestimates it at higher vertical wave numbers, which is consistently observed during all the months. The observed discrepancies are attributed to the differences in the slopes of theoretical and observed gravity wave spectra. The slopes of the observed vertical wave number spectra are estimated and compared with the model spectrum slope, which are in good agreement. The estimated slopes of the observed monthly vertical wave number spectra are in the range of −2 to −2.8. The significance of the present study lies in using the ten years of data to estimate the monthly mean vertical wave number spectra of gravity waves, which will find their application in representing the realistic gravity wave characteristics in atmospheric models.

Predicting aphid (Lipaphis erysimi) growth in oilseed Brassica using near surface meteorological data from NOAA TOVS—a case study

Pest infestation in crops is highly influenced by agrometeorological parameters. Weather based early warning of pest infestation is being practised using statistical and dynamic simulation models on point scale. Satellite based inputs and epidemiological models can extend the application to areas with irregular and non‐existing ground observations. The present study describes the use of National Oceanic and Atmospheric Administration TIROS (Television and InfraRed Operational Satellites) Operational Vertical Sounder (TOVS) near surface air temperature at 1430 h Local Apparent Time (LAT) over India (0900 Universal Time Code) for modelling onset, build‐up and peak aphid (Lipaphis erysimi) infestation on Indian Mustard (Brassica juncea) crop over Bharatpur and Kalyani, falling in semi‐arid and sub‐humid regions, respectively. The daily cumulative TOVS air temperature from 1 October 2001 showed high correlation (R 2: 0.99) with observed datasets. Exponential relationships were found to be the best empirical fit between TOVS cumulative air temperature (CATTOVS) and crop age at aphid onset (R 2: 0.7–0.99) and peak infestation (R 2: 0.91–0.95) for two stations representing semi‐arid (Bharatpur) and sub‐humid (Kalyani) agroclimatic conditions. Second order polynomial fits were found (R 2: 0.81–0.85) at both the stations between peak aphid count and CATTOVS at peak. Estimates of intermediate linear aphid build‐up to peak, computed using location‐specific linear growth rate (LGR) showed a higher standard error (SE) of 20% of mean at Kalyani (0–99), compared to 8% at Bharatpur (4–58). The common prediction models on linear start and peak were developed using TOVS noon time specific humidity (SPH) weighted thermal units and sowing dates. The standard error (SE) of estimated intermediate aphid‐build‐up became less: 4.5% of observed mean counts for pooled datasets with a common model, irrespective of sowing dates. The correlation between estimates and observations was 71%. The common model will be useful for general application in the absence of availability of local models.

Labtermo: Methodologies for the calculation of the corrected temperature rise in isoperibol calorimetry

In isoperibol temperature-rise calorimetry, different approaches can lead to the corrected temperature rise. The description of the methodology, as well as an improvement in the approach to the accurate numerical calculation of the corrected temperature rise in isoperibol calorimetry, based on the comparison between the exponential functional description of the initial and final periods and an independent third order polynomial fitting, is presented. The latter is focused on the strategy of minimizing the result dependency on the definition of the main period of the reaction. Furthermore, the dedicated software application Labtermo is introduced.

Nonlinear dynamic analysis of an elastic beam isolator sliding on frictional supports

The dynamic behavior of an elastic beam free to slide on two frictional supports is studied under sinusoidal and random excitations. The beam force–deflection relationship, originally expressed in terms of elliptic functions, is approximated by a polynomial fit of eleventh order. The friction force is modeled in terms of the sliding velocity and the end slope angle. Under sinusoidal excitation, the equation of motion of the system is solved numerically and the solution is utilized to estimate the system transmissibility. It is found that when the excitation frequency is increased beyond resonance, the friction at the sliding supports improves the transmissibility. The dependence of the response on initial conditions establishes the basins of attraction for different values of friction coefficient and excitation parameters. The dependence of the safety integrity factor on excitation amplitude level and friction coefficient reveals that the friction extends the stable region. Under random excitation, the system response statistics are estimated from Monte Carlo simulation results for different values of friction coefficient and excitation power spectral density level. The friction is found to result in a significant reduction of the system response mean square.

Aspartame tablets—gamma dose response and usability for routine radiation processing dosimetry using spectrophotometry

Aspartame tablets were studied for gamma dose response, using spectrophotometric read-out method. The optimum concentration for ferrous ions was 2 × 10 - 4 mol dm - 3 and xylenol orange with 2.5 × 10 - 1 mol dm - 3 of sulphuric acid for the optimum acidity in FX solution. Wavelength of maximum absorbance is 548 nm. Post-irradiation stability is appreciable i.e. for not less than one month. Dose response is non-linear with third order polynomial fit, in the dose range of 1000–10000 Gy. This system of aspartame was further used for carrying out relative percentage dose profile measurement in Gamma Cell-220. Results obtained were inter-compared with that of a glutamine dosimeter, which showed that maximum difference between the values of aspartame and glutamine systems is within ± 10 % .

Investigation into the wavelength dependence of the aerosol optical depth in the Athens area

AbstractGround‐based solar spectral irradiance measurements obtained by a spectroradiometer have been used to retrieve the aerosol optical depth, τα, and the Ångström wavelength exponent, α. These measurements were obtained in the Athens centre in May 1995. Exponent α is frequently computed from spectral measurements both from ground‐based photometers and satellite remote sensing retrievals. Although the retrieval of α has been the subject of many studies worldwide, its spectral variation is typically not considered. In this study we analyse the spectral measurements of ln τα versus ln λ, where λ is the wavelength, at six selected wavelengths which cover the spectrum from 340 to 870 nm. It is obvious that there is significant curvature in the ln ta versus ln λ relationship, and the reasons for this are examined. It was found that this curvature depends on both atmospheric turbidity and aerosol optical properties, and a second order polynomial fit provides excellent agreement. The curvature of the polynomial equation becomes greater as the aerosol loading alters from high to low. The curvature is characterized by the second derivative of α, which can be utilized in conjunction with α to characterize the spectral dependence of aerosol optical depth, and can also be used as an indicator of the relative influence of fine‐versus coarse‐mode particles. Copyright © 2006 Royal Meteorological Society

Individual Pulses Behaviour of PSR B0950+08 at 111 MHz

We carried out an analysis of the behaviour of individual pulses of PSR B0950+08 based on our observations at a frequency 111.2 MHz. The intensity and phase distribution of pulses at different longitudes of the pulsar average profile was investigated. The intensity of individual pulses can exceed ten times the average profile amplitude. It was shown that the intensity distribution of weak pulses with longitude of their appearance differs strongly from the distribution of strong pulses. The flux density of the average pulse changes by a factor of up to 13 from day to day, due to interstellar scintillation. It was shown that the cumulative distribution function is described by a polynomial fit of the second order in log-log scale.

TU-EE-A1-06: Application of TG_43U1 Formalisms to Calculate Dose Distribution Around a 5 Cm Long RadioCoil Source

Purpose: To evaluate application of TG‐43U1 parameters for the determination of dose distribution around a 5cm long RadioCoilTM™ source. In addition TG‐43U1 recommended linear interpolation technique for 2D anisotropy function (F(r,θ) has been evaluated for elongated sources. Materials and Methods:Dosimetriccharacteristics of 5cm long RadioCoil™ brachytherapy source have been determined following TG‐43U1 recommendations using MCNP5 Monte Carlo code. In addition dose profiles along the longitudinal axis of the 5cm long source have been determined using MCNP5 simulation and theoretical technique. Monte Carlo calculated dose profiles were compared with theoretically values to evaluate accuracy of TG‐43U1 recommended formalisms for elongated brachytherapy sources. Results: TG‐43U1 recommended dosimetriccharacteristic were utilized to calculate dose distribution around an elongated brachytherapy source. Fifth order polynomial fit to the F(r,θ) was applied to extend F(r,θ) from 0° to 90° for the points falling on the source. Dose profiles at radial distances 0.5, 1.0, 1.5, and 2.0cm away from the central axis of the source has been determined using Monte Carlo simulation technique and TG‐43U1 recommended formalisms. Results of theoretically calculated dose profile were compared with Monte Carlo simulation data. Application of TG‐43U1 recommended minimal radial distances for 2D anisotropy function for dose calculation indicated that F(r,θ) for additional radial distances are required for good agreement between the two methodologies for calculating dose distribution. In addition, linear interpolation technique recommended by TG‐43U1 has also been investigated to extract F(r,θ) for the points falling in between the TG‐43U1 recommended radii. Conclusion: Results of these investigations indicate that TG‐43U1 formalisms can be extended for elongated brachytherapy sources, if F(r,θ) is tabulated for radial distances of 0.5 to 5.0cm with 0.5cm increment L/2 ± 0.2cm. Moreover, with the addition of recommended radial distances for 2D anisotropy functions, the linear interpolation technique more closely replicates Monte Carlo simulated data.

In vitro ultrasonic characterization of human cancellous femoral bone using transmission and backscatter measurements: Relationships to bone mineral density

Thirty-eight slices of pure trabecular bone 1-cm thickness were extracted from human proximal femurs. A pair of 1-MHz central frequency transducers was used to measure quantitative ultrasound (QUS) parameters in transmission [normalized broadband ultrasound attenuation (nBUA), speed of sound (SOS)] and in backscatter [broadband ultrasound backscatter (BUB)]. Bone mineral density (BMD) was measured using clinical x-ray quantitative computed tomography. Site-matched identical region of interest (ROIs) of 7 x 7 mm2 were positioned on QUS and QCT images. This procedure resulted in 605 ROIs for all the specimens data pooled together. The short-term precision of the technique expressed in terms of CV was found to be 2.3% for nBUA, 0.3% for SOS and 4.5% for BUB. Significant linear correlation between QUS and BMD were found for all the 605 ROIs pooled, with r2 values of 0.73, 0.77, and 0.58 for nBUA, SOS, and BUB, respectively (all p < 0.05). For the BUB, the best regression was obtained with a polynomial fit of second order (r2 = 0.63). An analysis of measurements errors was developed. It showed that the residual variability of SOS is almost completely predicted by measurements errors, which is not the case for BUA and BUB, suggesting a role for micro-architecture in the determination of BUA and BUB.

Discharge Rating Curve Extension – A New Approach

It is often necessary to have stage discharge curve extended (extrapolated) beyond the highest (and sometimes lowest) measured discharges, for river forecasting, flood control and water supply for agricultural/industrial uses. During the floods or high stages, the river may become inaccessible for discharge measurement. Rating curves are usually extended using log–log axes, which are reported to have a number of problems. This paper suggests the use of Support Vector Machine (SVM) in the extrapolation of rating curves, which works on the principle of linear regression on a higher dimensional feature space. SVM is applied to extend the rating curves developed at three gauging stations in Washington, namely Chehalis River at Dryad and Morse Creek at Four Seasons Ranch (for extension of high stages) and Bear Branch near Naselle (for extension of low stages). The results obtained are significantly better as compared with widely used logarithmic method and higher order polynomial fitting method. A comparison of SVM results with ANN (Artificial Neural Network) indicates that SVM is better suited for extrapolation.

Testing of a hot- and cold-wire probe to measure simultaneously the speed and temperature in supercritical CO2 flow

The use of hot-wire anemometry in carbon dioxide flow under supercritical conditions has been analyzed and implemented for the first time. A two-sensor probe to simultaneously measure streamwise velocity and temperature in this flow has been designed and constructed. A calibration and test flow loop that can provide supercritical state conditions above the critical point has been also designed, fabricated and tested. The temperature and velocity flow fields of the flow loop can be varied at constant pressure. It has been found that, above the pseudo-critical temperature, the velocity sensor response fits King’s cooling law with a high correlation coefficient. The dependence of the King’s law parameters on temperature can be accurately presented with second or higher order polynomial or exponential fits, depending on the extent of the temperature range. Below the pseudocritical temperature the data is scattered, and the variation with temperature of the King’s law parameters, determined from calibration, is irregular. The influence on this data scatter of the strong variation of the fluid properties near the critical point is analyzed, and a possibility to reduce it is proposed. The temperature sensor response both above and below the pseudocritical temperature is similar to the response under normal conditions. It is linear with a very high correlation coefficient between the calibration data and the fitted curve. It is also shown that the temperature response is not affected by variation of the flow’s speed.

Gamma and UV radiation effects on breakdown voltage of neon-filled tube

This paper presents the experimental data of breakdown voltage as a function of afterglow period and voltage increase rate for neon-filled tube at pressure of 6.6 mbar. The measurements and data acquisition of breakdown voltage were performed using a digital system. The influence of gamma radiation and ultraviolet radiation on breakdown voltage was analyzed. The values of static breakdown voltage for different values of exposed dose rates of gamma radiation were estimated on the basis of the experimental breakdown voltage data using a second order polynomial fit.

Impact of thermal dependence of elastic constants on surface stress measurements

The accuracy of surface stress data obtained by means of bending sample methods depends on the precise knowledge of the biaxial Youngs modulus E/1−ν which enters as a prefactor in the stress calculation formula of Stoney and describes the stiffness of the sample’s material against biaxial deformation. Room temperature values are commonly used for E/1−ν. However, E/1−ν is significantly temperature dependent. A second order polynomial fit of this dependence is presented for the benefit of future measurements as well as a correction curve for old data.

Theoretical and experimental determination of dosimetric characteristics for brachyseed ™ Pd-103, model Pd-1, source

Dosimetric characteristics of the BrachySeed™ Pd-103, Model Pd-1 source have been determined using both theoretical and experimental methods. Dose rate constant, radial dose function, and anisotropy functions of the source have been obtained following the TG-43 recommendations. Derivation of the dose rate constant was based on recent NIST WAFAC calibration performed in accordance with their 1999 Standard. Measurements were performed in Solid Water™ using LiF TLD chips. Theoretical simulation calculations were performed in both Solid Water™ and water phantom materials using MCNP4C2 Monte Carlo code using DLC-200 interaction data. The results of the Monte Carlo simulation indicated a dose rate constant of 0.65 cGy h −1 U −1 and 0.61 cGy h −1 U −1 in water and Solid Water™, respectively. The measured dose rate constant in Solid Water™ was found to be 0.63±7% cGy h −1 U −1, which is within the experimental uncertainty of the Monte-Carlo simulated results. The anisotropy functions of the source were calculated in both water and in Solid Water™ at the radial distances of 1 to 7 cm. Measurements were made in Solid Water™ at distances of 2, 3, 5, and 7 cm. The Monte-Carlo calculated anisotropy constant of the new source was found to be 0.98 in water. The tabulated data and 5th order polynomial fit coefficients for the radial dose function along with the dose rate constant and anisotropy functions are provided to support clinical use of this source.

An approach to the three-dimensional display of left ventricular function and viability using MRI.

Cardiac MRI was performed in human volunteers to determine the magnitude of the misregistration (MSR) of cardiac landmarks due to variability in the diaphragm position for repeated breath-holds. Seven normal volunteers underwent MR imaging of the left ventricle (LV) to evaluate the magnitude of the endocardial centroid MSR. The MSR for a mid-ventricle short-axis image was 3.01 +/- 1.68 mm through-plane and 4.16 +/- 1.62 mm in-plane. A second order polynomial fit through the LV centroid coordinates minimized the in-plane component of the MSR error. Short-axis cine images, corrected for MSR, provided high-resolution 2D data from which an accurate anatomical model of the LV was generated. Anatomical landmarks were used to register parametric maps of myocardial perfusion and viability to the three-dimensional (3D) model, with the corresponding parameters displayed as color-encoded values on the endo- and epicardial surfaces of the LV. Registration of regional wall motion, perfusion and viability to the 3D model was performed for three patients with a history of cardiovascular disease. The proposed 3D reconstruction technique allows visualization in 3D of the LV anatomy, in combination with parametric mapping of its functional status.