New Method For Calibration Research Articles

A new method for calibration of personal neutron track dosimeters

The calibration method discussed in this paper is based on a conceptual relationship between personal dose equivalent and neutron-induced alpha particle tracks and/or neutron-induced recoiled tracks on the polycarbonate detector when used as a part of polymeric personal albedo neutron dosimeter. The relationship represents personal dose equivalent as a function of track density of the second-order polynomial form. The parameters of the calibration relationship were optimized by fitting low detectable track density up to highest possible track density of which a significant part consisted of non-resolvable overlapped tracks, as seen by a scanning system. Our personal albedo neutron dosimeter was irradiated on a standard rectangular cubic water phantom using 252Cf and 241Am-Be reference neutron sources and the effect of scattered neutrons on the detector response was corrected by employing an analytical method, which is discussed in this paper.

High pressure thermal expansion of gases: measurements and calibration

A set-up based on transitiometric principles has been designed for direct measurements of high pressure cubic expansion coefficient of gases. A new method of calibration was presented for pressure-controlled calorimeters working with open mass calorimetric vessels. The new method is based on heat capacity standards and thus is a complementary to the previous methods based on thermal expansion standards. The calibrations performed with the new method using a number of heat capacity standards demonstrated that the calibration constant of correctly designed calorimetric vessels does not depend on pressure. The results of test measurements with nitrogen performed accordingly to the thermodynamic foundations of the method are in satisfactory agreement with the literature data.

A new method of calibration for the empirical loglikelihood ratio

The Chi-square calibration for the empirical loglikelihood ratio refers to the method of approximating quantiles of the finite sample distribution of the empirical loglikelihood ratio with that of the limiting Chi-square distribution. Empirical likelihood ratio confidence regions are usually computed with the Chi-square calibration. Such Chi-square calibrated confidence regions can have a serious undercoverage problem. This paper examines the undercoverage problem from a finite sample standpoint and proposes a method of calibration which approximates the finite sample distributions with a new family of distributions. The new distributions is another family of sampling distributions arising from the normal distributions and is derived through a simple finite sample similarity between the empirical and parametric likelihoods. The new method of calibration is as easy to use as the Chi-square calibration. It corrects the undercoverage problem of the Chi-square calibration and is consistently more accurate.

A new method of calibration for the empirical loglikelihood ratio

The Chi-square calibration for the empirical loglikelihood ratio refers to the method of approximating quantiles of the finite sample distribution of the empirical loglikelihood ratio with that of the limiting Chi-square distribution. Empirical likelihood ratio confidence regions are usually computed with the Chi-square calibration. Such Chi-square calibrated confidence regions can have a serious undercoverage problem. This paper examines the undercoverage problem from a finite sample standpoint and proposes a method of calibration which approximates the finite sample distributions with a new family of distributions. The new distributions is another family of sampling distributions arising from the normal distributions and is derived through a simple finite sample similarity between the empirical and parametric likelihoods. The new method of calibration is as easy to use as the Chi-square calibration. It corrects the undercoverage problem of the Chi-square calibration and is consistently more accurate.

Calibration of positron emission tomograph detector modules using new neural method

A new method for calibration of positron emission tomography detector modules is proposed. A purposely-modified version of the standard neural self-organising map is adopted. Experimental results to assess accuracy and efficiency of the proposed method are included.

A New Method for Thread Calibration on Coordinate Measuring Machines

This paper presents a new method for the calibration of thread gauges on coordinate measuring machines. The procedure involves scanning of thread profiles using a needle-like probe, achieving traceability by substitution of different thread portions with corresponding paths on a calibrated sphere. The feasibility of applying the method to calibrate a parallel thread gauge with respect to all the relevant thread parameters was demonstrated experimentally using a precision CMM. Application of the comparator approach as described in ISO DTS 15530-3 gave measuring uncertainties comparable to the values from usual calibration methods on dedicated equipment, e.g. a measuring uncertainty of 1.8 μm was achieved for measurement of the pitch, and 2-2.5 μm for diameter measurements.

Calibration of chiral compounds with self-internal standard. Application to calibration of propranolol hydrochloride in capillary zone electrophoresis

A new method of calibration designed for chiral compounds named: Calibration with Self-internal Standard, is suggested. Here, the second enantiomer serves as the internal standard, the total concentration of both enantiomers is known and kept constant. The method is an alternative to the commonly used calibration with an internal standard being a chemically different compound. The applicability of the method is demonstrated on the calibration of propranolol hydrochloride in capillary zone electrophoresis. Statistical characteristics of the method are compared to calibration without an internal standard and with L-tryptophan as internal standard.

Comparison of two methods of therapy level calibration at 60Co gamma beams

The accuracy and traceability of the calibration of radiotherapy dosimeters is of great concern to those involved in the delivery of radiotherapy. It has been proposed that calibration should be carried out directly in terms of absorbed dose to water, instead of using the conventional and widely applied quantity of air kerma. In this study, the faithfulness in disseminating standards of both air kerma and absorbed dose to water were evaluated, through comparison of both types of calibration for three types of commonly used radiotherapy dosimeters at 60Co gamma beams at a few secondary and primary standard dosimetry laboratories (SSDLs and PSDLs). A supplementary aim was to demonstrate the impact which the change in the method of calibration would have on clinical dose measurements at the reference point. Within the estimated uncertainties, both the air kerma and absorbed dose to water calibration factors obtained at different laboratories were regarded as consistent. As might be expected, between the SSDLs traceable to the same PSDL the observed differences were smaller (less than 0.5%) than between PSDLs or SSDLs traceable to different PSDLs (up to 1.5%). This can mainly be attributed to the reported differences between the primary standards. The calibration factors obtained by the two methods differed by up to about 1.5% depending on the primary standards involved and on the parameters of calculation used for 60Co gamma radiation. It is concluded that this discrepancy should be settled before the new method of calibration at 60Co gamma beams in terms of absorbed dose to water is taken into routine use.

Balloon-borne far-infrared Fabry–Perot spectrometer for astrophysical observations

The balloon-borne cryogenic far-infrared spectrometer (FIS) described in this paper is a liquid-helium cooled direct-detection spectrometer which covers the wavelength range from 140 μm to 220 μm. The spectral resolution R is about 2000. FIS is based on two scanning Fabry–Perot interferometers (SFPs) whose reflector gaps can be varied continuously over more than 200 μm by the magnetic force of superconducting coils. FIS has been developed to measure far-infrared emission lines from star-forming regions. The most prominent among these are the 157 μm [CII] line and the 205 μm [NII] line. In order to perform the calibration of FIS during the flight preparation at the balloon-launch facility of CNES in Aire sur l'Adour (France), we have devised a new method of calibration of FIS which is performed exclusively with the help of an evacuable absorption cell. In-flight tests in the stratosphere have confirmed that all components of the instrument work. This test permitted us to estimate the system noise equivalent power (NEP sys). It is in the expected range of about 10 −14 W/Hz 1/2 at the wavelength of 157 μm and of about 2×10 −14 W/Hz 1/2 at 205 μm wavelength.

Heat Transfer Committee Best Paper of 1995 Award: Distribution of Film-Cooling Effectiveness on a Turbine Endwall Measured Using the Ammonia and Diazo Technique

The distribution of adiabatic film-cooling effectiveness on the endwall of a large-scale low-speed linear turbine cascade has been measured using a new technique. This technique is based on an established surface-flow visualization technique, and makes use of the reaction between ammonia gas and a diazo surface coating. A new method of calibration has been developed to relate the result of the reaction to surface concentration of coolant. Using the analogy that exists between heat and mass transfer, the distribution of film-cooling effectiveness can then be determined. The complete representation of the film-cooling effectiveness distribution provided by the technique reveals the interaction between the coolant ejected from the endwall and the secondary flow in the turbine blade passage. Over- and undercooled regions on the endwall are identified, illustrating the need to take these interactions into account in the design process. Modifications to the cooling configuration examined in this paper are proposed as a result of the application of the ammonia and diazo technique.

New method of calibration for glow discharge optical emission spectrometry

In glow discharge optical emission spectrometry (GD-OES), approximation of matrix independent emission yields has frequently been used, in which the emission intensity of an atomic line is proportional to the product of the concentration of the corresponding element and the sputtering rate of the sample. If calibration data obtained with GD-OES for several elements are available, it is possible with this approximation to determine the sputtering rates for calibration samples by the procedure described, termed multi-element calibration. An example of multi-element calibration is presented for high-speed tool steels. Possible consequences for the quantification of GD-OES analyses are discussed.

Development of a new method for calibration of pneumotachograph according to flow rate--evaluation of a computer-controlled-system for assessing respiratory gas exchange using this method

1) We evaluated the method for calibrating the pneumotachograph according to flow rate by the software on personal computer. Flow volume was detected using the approximated equation (y = 1.294x2 + 0.989x + 35.824, r = 0.976, p less than 0.01) from various mean flow rate and integration of output voltage. The error between syringe volume (21) and the estimated value on the equation was 10 +/- 8 ml (0.48 +/- 0.42%). 2) Using the method described in 1), we developed computer-controlled-system for assessing respiratory gas exchange by mixing chamber method. To evaluate the accuracy of the system as compared with the Douglas Bag method, we measured the gas parameters of the both methods for two male subjects at rest(3 and 5min) and steady state exercise (3 min., 60-240watt). The error between the both methods were within +/- 5% in ventilation(VE), mixed expired O2 (FEO2) and CO2 (FECO2) concentration, and were within +/- 8% in O2 uptake(VO2) and CO2 production (VCO2). There were high positive correlation (r greater than 0.99, p less than 0.01) between the both methods in the all parameters. These results indicate that the system in this study would be practical use, that VE can be measured in only one pneumotachograph, even if the range of flow rate was wide(e.g. from rest to heavy exercise).

Study on the concentration effects in GPC: 5. A new method for calibration on universal calibration curves with polydispersed polymers

A new method for calibration of universal calibration curves with polydispersed polymers is presented. It is based on a model theory of concentration effects in GPC for polydispersed polymers. A general correlation between the peak hydrodynamic volumes and the elution volumes for polydispersed polymers was established. The chromatograms of polystyrene (PS), polydocylmethacrylate (PDCMA) and polytridecylmethacrylate (PTDMA) of different molecular weights and their distribution in THF solvent were studied. These experimental data were treated with the general relation and the universal calibration curves for mono- and polydispersed polymers were constructed. It is found that the two universal calibration curves with mono- and polydispersed polymers are in excellent agreement.

Prediction of Future Observations in Growth Curve Models

The problem of predicting a future measurement on an individual given the past measurements is discussed under nonparametric and parametric growth models. The efficiencies of different methods of prediction are assessed by cross-validation or leave-one-out technique in each of three data sets and the results are compared. Under nonparametric models, direct and inverse regression methods of prediction are described and their relative advantages and disadvantages are discussed. Under parametric models polynomial and factor analytic type growth curves are considered. Bayesian and empirical Bayesian methods are used to deal with unknown parameters. A general finding is that much of the information for forecasting is contained in the immediate past few observations or a few summary statistics based on past data. A number of data reduction methods are suggested and analyses based on them are described. The usefulness of the leave-one-out technique in model selection is demonstrated. A new method of calibration is introduced to improve prediction.

HFS and isotope shift in the atomic spectrum of205Pb

The hfs of205Pb in the 283.3-nm resonance line and its isotope shift (IS) have been measured in absorption with the use of dispersive spectroscopy. A new method for calibration and analysis, when internal standards are not available is described. The results are: hfs interaction constantsA=70.3(5)×10−3 cm−1,B=−0.6(1.1)×10−3 cm−1,205Pb-208Pb IS=−123.9(2.0)×10−3 cm−1. The derived nuclear magnetic dipole moment,μ=0.704(5)μ N is in good agreement with values calculated with a nuclear configuration mixing model.

Measurement of residual-stress distribution by the incremental hole-drilling method

The hole-drilling method is widely used for the measurement of residual stresses in mechanical components. Recent developments have shown that strains measured on the surface during an incremental drilling can be related to residual-stress distribution. Researches, internationally, have proposed different methods of calibration which lead to results of varying degrees of accuracy. The present paper discusses the different approaches used. A new method of calibration is proposed and it is shown how the finite element analysis can be used for the determination of the correlation coefficients. The variation of the strains measured on the surface for each increment is due, firstly to the residual stresses in the layer and secondly, to the change of the hole geometry. Most authors do not consider the latter aspect, but the presently reported results show that this causes a significant error in the experimental data. The finite-element method has been used for the computation of the coefficients for all types of strain-gauge rosettes when the hole diameter is pre-determinated. Another problem of the hole-drilling method is the selection of the drilling tool. Two systems have been studied: the use of a ultra high-speed air-turbine and the use of a conventional milling machine. The incremental hole drilling method has been applied to both shot-peened and water-quenched test specimens, and results have been successfully compared with those of the bending deflection and the X-ray method.

Evaluation of a calibration marker scheme for open tubular column gas chromatography with on-column injection and electron-capture detection

A new method of calibration for open tubular column gas chromatography with electron-capture detection is proposed. A homologous series of n-alkyl bromides is added to each sample analyzed to provide simultaneously a retention index scale and a method of solute calibration. The detector response to equimolar amounts of n-alkyl bromides is constant, permitting a calibration curve to be generated for each sample by adding a series of n-alkyl bromides arranged in increasing stepwise molar concentrations. Each solute is then treatd as if it were an imaginary n-alkyl bromide of some concentration obtained from the experiment and converted to an actual concentration from the relationship between the solute and n-alkyl bromide calibration curves, stored in the computer memory. It is shown that for the complete chromatographic system, temperature-programmed retention indices can be reproduced with an average standard deviation of ca. 0.35 index units and that the relative error for the calibration melthod is similar to that obtained by daily solute calibration. The advantages of the new method are that it combines the operation of solute identification by retention index values and multiple solute calibration into a single method, capable of automation. Compared to standard calibration procedures, it is less time-consuming and subject to fewer operator errors.

A new calibration method for tritium autoradiographs

A new method for calibration of tritium autoradiographs was developed to facilitate and speed up the procedure. In this method xylene solutions of tritiated poly- n-butylmethacrylate standard pipetted onto object slides are used as reference. The method was compared by means of analysis of variance to a more laborious conventional procedure in which sections of solid methacrylate are used. No difference was observed in the accuracy of the two methods.

A variable angle method of calibration for X-probes applied to wall-bounded turbulent shear flow

A variable angle calibration technique for hot wire and hot film X-probes incorporating a new method of interpolation is described here along with measurements in a fully developed turbulent channel flow. Results based on the new method of calibration include the mean velocity profile, Reynolds stress, and probability density distributions for fluctuating velocity components u and υ and for the flow angle. Also skewness and flatness factors for u and υ are given. Measurement data were also evaluated using the conventional method. A comparison of both techniques shows that the new method does not yield appreciable differences in statistical flow analyses but is more accurate in measuring rare flow events associated with large flow angles. An extended version of the new method of calibration allowing three dimensional measurements in turbulent flow will be discussed.

Physical state of airborne p, p'-diphenylmethane diisocyanate (MDI) and its measurement.

The current exposure standard of 0.02 ppm ceiling for MDI by definition refers to a gaseous species. The standard method, recommended by NIOSH, for measuring MDI in air, is also based on the the assumption that MDI is in the gas phase. Investigations in our Unit indicate that a major portion of airborne MDI, in working environments during spraying operations, is present as an aerosol. In view of this finding, the standard method would underestimate the MDI concentration and describing the airborne MDI concentration in "ppm" or "volume/volume unit" in invalid. A new method for calibration of the continuous reading monitors to measure airborne MDI concentration in mg/m3 unit is described.