Showing papers on "Calibration curve published in 1969"

Correction for temperature loading and high gas pressure effects for the constant-temperature hot-wire anemometer

Abstract: An improved method of calculating the calibration curve for the constanttemperature hot-wire anemometer operating with high wire temperatures is described. Experimental results at high pressure and gas temperature conditions are also included.

Photographic Emulsion Calibration with the Use of a Digital Computer

Abstract: A computer program, written in FORTRAN IV, has been developed for the calibration of photographic emulsions using the two-step method of Churchill. Innovations in this program are: (1) the proportional weighting of all points used in the construction of the preliminary curve to their precision of determination; (2) the examination of the preliminary curve of best fit with the rejection of spurious values; and (3) an automatic increase of the degree of the equation used if a random scatter of points about the preliminary curve has not been found. A table relating relative intensities to percent transmittance is printed and a data card containing the coefficients of the emulsion calibration curve is punched.

Statistical treatment of rain gauge calibration data

Abstract: This paper describes the statistical treatment of the calibration data of the capacitance gauges used for measurement of rain rates in the rain gauge network set up in a 160 square kilometer area surrounding Crawford Hill, Holmdel, New Jersey. The expression R = αe−βf, where R is the rain rate in millimeters per hour, f is the frequency of the rain gauge oscillator, and α and β are fitted coefficients, allows calibration curves to be developed for all 99 of the devices in the system with an overall equivalent standard error of 7.3 millimeters per hour. This paper discusses the distribution of parameters and residuals and gives a refinement which corrects for a fitting bias.

Calibration of the High-Volume Air Sampler

Abstract: The use of either a variable voltage transformer (Variac) for regulating the fan speed or resistances has been widely accepted for varying the air flow through a high-volume sampler during calibration Calibration data for the Staplex high-volume sampler demonstrate that significant differences exist between the calibration results obtained by the two metheds Calibration curves obtained with a bellows-type dry gas meter and a rotating vane anemometer clearly illustrate that resistances should be used as the standard procedure for varying the flow rate during calibration of the Staplex high-volume sampler A simplified calibration procedure utilizing a rotating vane anemometer at the sampler inlet is described

Installation and field calibration of neutron‐scatter equipment for hydrologic research in heterogeneous and stony soils

Abstract: The commonly used methods of access tube installation and neutron depth probe calibration were impractical in the stony soils of an agricultural watershed in eastern Pennsylvania. Modification of a portable power-driven drilling machine made it possible to drill straight boreholes to a depth of 24 feet through the soil and the underlying shale beds. Backfilling oversize holes around the access tubes with fine soil material gave satisfactory results. Reasonable correspondence was found between calibration curves from heterogeneous, stony sites and more precise data obtained at a site with alluvial, stone-free soil derived from the stony residual soils upstream. The field calibration curves were roughly parallel to the calibration curve supplied by the manufacturer of the probe but were displaced upward by approximately 4000 counts per minute. Use of the factory calibration curve would be adequate for determining relative changes in soil moisture content but would result in serious error if used for calculating the absolute moisture content.

Non-destructive measurement of carrier concentration in epitaxial gallium arsenide

Abstract: Infra-red reflection measurements have been performed on specimens of n-type epitaxial gallium arsenide in the spectral range 10-200 cm−1 From measurements of the wavelength position of the plasma absorption edge the carrier concentration in these samples has been determined, using a calibration curve produced by measurements on bulk single-crystal samples of known concentration - between 1015 and 1017 carriers/cm3

Evaluation of nuclear methods of determining surface in situ soil water content and density

Abstract: : Laboratory tests were conducted to evaluate the accuracy and reliability of measuring surface in situ soil water content and density by the backscatter and direct transmission nuclear methods using a single nuclear device and scaler. The nuclear device functioned as a surface backscatter moisture and density meter or as a direct transmission density probe. To determine the accuracy of the nuclear measurements, it was necessary to know the actual density and water content of the test soil. Boxes were fabricated to exact dimensions, filled with uniformly compacted soil, and weighed, and actual average soil density values were calculated. Five soil types were tested to approximate a full range of possible construction materials. Each soil type was tested at eight different densities and water contents. To obtain comparative results, soil densities of each sample were determined by two accepted conventional methods (sand-cone and water-balloon) for determining density in the field. Test results indicated that in situ densities determined by the direct transmission nuclear method using the factory calibration curve furnished with the device were as accurate as densities obtained by the sand-cone and water-balloon methods. The direct transmission nuclear method using a WES-developed calibration curve provided slightly more accurate density measurements than either conventional method. A test procedure for determining surface layer density and water content of soil by nuclear methods is presented in Appendix A.

Alternating Current Polarographic Determination of Dissolved Oxygen in Gasoline

Abstract: In view of the well known fact that dissolved oxygen plays a very important role in petroleum refinery, the present investigation was undertaken to establish a rapid and accurate method for the determination of dissolved oxygen in gasoline . In 1924 Heyrovsky first reported that dissolved oxygen is reduced at the dropping mercury electrode to produce two waves3) . The first wave results from reduction to hydrogen peroxide :O2+2H++2e→H2O2(acid medium)O2+H2O2+2e→HO2-+OH-(neutral or alkaline medium).The second wave corresponds to the reduction of the hydrogen peroxide either to water or hydroxyl ion, depending on the pH:H2O2+2erarr;2H2O(acid medium)HO2-→3OH-(alkaline medium).The diffusion currents are normally well-defined and show a linear dependence on oxygen concentration. However, three main difficulties are encountered in the application of a.c, polarography to the determination of oxygen in gasoline: the limited solubility of gasoline in aqueous or semi-aqueous electrolyte system, the exclusion of atmospheric oxygen in handling sample and the accurate calibration of calibration curve. The first difficulty was resolved by adopting a supporting electrolyte of sodium hydroxide in absolute alcohol and the second by the disign of a special polarographic cell. Two ways of accurate calibration were investigated: by using water of known dissolved oxygen content directly as a calibration standard, and by using air-saturated alcoholic electrolyte as a secondary standard, the dissolved oxygen content being determined polarographically using water as a primary standard .

Hydrocarbon Type Analysis in Petroleum Fraction by High Resolution Mass Spectrometry

Abstract: In this work, the type-analysis of hydrocarbons in petroleum fractions was carried out by means of high resolution mass spectrometer (Mattauch-Herzog type, Nihon Densi JMS-01 SG). The following conclusions were obtained:(1) The calibration curve, which represents the relationships between the intensity of the spectral lines and the concentration of the associated components, was linear by adopting both the two-step method and the Seidel function.(2) To get good results in the hydrocarbon type-analysis, sensitivity of the component must be corrected for the equipment and the measurement conditions, instead of using those reported by Gallegos et al.(3) The obtained results of the type-analysis with the middle-distillate-fractions were in good agreement with those obtained by use of G.C., U.V. and N.M.R..

原子吸光分析法による有害性金属の定量(第3報) : 長吸収管を用いた微量鉛の定量

Abstract: A rapid and convenient method for the determination of microamount of lead in foods and pharmaceuticals by atomic absorption spectrophotometry was described. The absorption tube 50 cm in length was used to improve the analytical sensitibity for lead. The samples were decomposed by the oxygen bomb method, and the combustion products were dissolved in 0.1 N nitric acid. pH of the solution was adjusted to 9-10, and the lead chelated with APDC (ammonium pyrrolidine dithiocarbamate) was extracted into chloroform. The chloroform solution was sprayed into the absorption tube by a mixture of air and hydrogen, and the absorption of lead was measured at 2833 A. Experimental conditions such as analytical lines, extraction of APDC-Pb complex into chloroform and the influence of coexsisting elements, were examined and the optimal conditions for the determination of lead were established. The linearity of calibration curve for lead was maintained in the range from 0.05 to 1.2 μg/ml. In the recovery test, mean value of recovery of lead added to glucose at levels between 5 and 15 μg was 93.0%. The analytical results obtained by present method for lead contained in polished rice, green tea and P. V. P. (polyvinylpyrrolidone) agreed well with those found by other methods including polarography.

Fluorometer Calibration Curves and Nomographs

Abstract: The relationship of rhodamine B dye fluorescence to water temperature is confirmed, and a procedure for calibrating a fluorometer for time-of-travel dye studies is described. Calibration nomographs for the four aperture settings designed into fluorometers are developed from experimentally derived temperature-fluorescence curves. The use of the nomographs expedites and simplifies field work and eliminates the need for standard dye solutions for determining unknown dye concentrations in streams when extreme accuracy is not warranted.

A new method for the fluorometric determination of micro quantities of citrate

Abstract: An extremely sensitive fluorometric procedure has been developed for the micro determination of citrate in various types of samples, based on the quenching effect of citrate on the fluorescence at 450 nm of the tungstate-flavanol complex. The calibration curve is linear in the 0 to 200 ppb range of citrate. With a slight modification of the method, citrate may be analyzed in the 0 to 5 ppm concentration range.

Cuantificación de cationes metálicos en agua con LIBS por deposición sobre una superficie de acero rayada con lápiz HB

Abstract: The use of laser-induced breakdown spectroscopy (LIBS) together with a pencil lead substrate for the quantitative analysis of salts dissolved in liquids provides is introduced as a very efficient and sensitive analytical method In this work we have compared five substrates over which aqueous solutions of salts were left to dry, and then submitted for analysis with LIBS The comparison was based in analytical parameters such as the sensitivity and linearity of each substrate We found that from these, the surfaces of graphite and a steel surface scratched with pencil HB gave the best results The concentration of the salt (cation) in the solution was made to correspond to the areas ofspecific peaks for each corresponding atom In this work, we used a method introduced by Jijon et al [1] for data handling This spectra selection method produces better linearity in calibration curves and much smaller errors that translate into correlation coefficients closer to 1, in this work correlations index up to 098 were determined We introduced an experimental setup with mirrors to study the self-absorption effect, showing in this work the lost of linearity in the peak areas at high concentrations We observed an indentation in the center of the Cs and K peaks, and the lost of signal LIBS of the spectrum of each peak analyzed with mirrors In the last part of this work, we applied the methodology for quantification introduced to quantification of arsenic dissolved in water, as a real life application for concentrations until 1000 ppm The non linear calibration curve for the whole range in this case was fitted to an exponential function with 0993 of correlation index The detection limit calculated for the arsenic in water was 32 ppm and this result is very satisfactory compared with those reported on literature for LIBS

Spektrochemische Bestimmung Der Spurenelemente in CaO - Matrixen

Abstract: An analytical method based on emission spectrography is described for the determination of the following trace elements: Ba, Co, Cr, Mn, Ni, Sc, Ti and V in CaO-matrix. The calibration curves have been constructed using the least squares method and the data treated statistically. Finally, the limits of detection, 1imits of guarantee for purity, and the precision of the method have been calculated.