Diffusion of Comets from Parabolic into Nearly Parabolic Orbits

1972 ◽  
Vol 45 ◽  
pp. 347-351 ◽  
Author(s):  
K. A. Shtejns
Keyword(s):  
Standard Deviation ◽  
Diffusion Theory ◽  
Semimajor Axis ◽  
Random Perturbations ◽  
Distribution Law ◽  
Mean Values ◽  
Mean Lifetime ◽  
The Mean ◽  
Parabolic Orbits ◽  
Good Agreement

It is assumed that the accumulation of small, independent, random perturbations in the reciprocal semimajor axis of the orbit of a comet follows a normal distribution law whose standard deviation is a function of the inclination and perihelion distance and that for nongravitational forces it is a function of perihelion distances only; it is also assumed that secular accelerations do not change into decelerations, and vice versa. The standard deviations given by diffusion theory are in good agreement with the mean values of nongravitational impulses obtained from calculations from short overlapping arcs. The mean lifetime of a comet is found to be one hundred revolutions. To explain why many more near-parabolic comets are actually discovered than are theoretically expected the existence of comets of very short lifetimes must be accepted.

scholarly journals Choice of positive distribution law for nuclear data

2018 ◽  
Vol 4 ◽  
pp. 38
Author(s):  
Sébastien Lahaye
Keyword(s):  
Standard Deviation ◽  
Nuclear Data ◽  
Mean Value ◽  
Distribution Law ◽  
Mean Values ◽  
Relative Standard ◽  
Distribution Laws ◽  
The Mean ◽  
Standard Deviations ◽  
Truncated Gaussian

Nuclear data evaluation files in the ENDF6 format provide mean values and associated uncertainties for physical quantities relevant in nuclear physics. Uncertainties are denoted as Δ in the format description, and are commonly understood as standard deviations. Uncertainties can be completed by covariance matrices. The evaluations do not provide any indication on the probability density function to be used when sampling. Three constraints must be observed: the mean value, the standard deviation and the positivity of the physical quantity. MENDEL code generally uses positively truncated Gaussian distribution laws for small relative standard deviations and a lognormal law for larger uncertainty levels (>50%). Indeed, the use of truncated Gaussian laws can modify the mean and standard deviation value. In this paper, we will make explicit the error in the mean value and the standard deviation when using different types of distribution laws. We also employ the principle of maximum entropy as a criterion to choose among the truncated Gaussian, the fitted Gaussian and the lognormal distribution. Remarkably, the difference in terms of entropy between the candidate distribution laws is a function of the relative standard deviation only. The obtained results provide therefore general guidance for the choice among these distributions.

Collaborative Comparison of Dumas and Kjeldahl Methods for Nitrogen in Feeds

1967 ◽  
Vol 50 (1) ◽  
pp. 38-41
Author(s):  
Melvin E Ebeling
Keyword(s):  
Standard Deviation ◽  
Collaborative Study ◽  
Mean Values ◽  
Nitrogen Determination ◽  
Kjeldahl Method ◽  
The Mean ◽  
Organic Standards ◽  
Good Agreement

Abstract A collaborative study to compare the Dumas and Kjeldahl methods for nitrogen determination in agricultural feed materials has been completed. The Dumas method used the Nitrogen Analyzer II, Coleman Model 29A. The mean values of the six feed materials studied showed good agreement between the two methods. Standard deviation ranged from ±0.18 to ±0.39 for the Dumas method and from ±0.06 to ±0.40 for the Kjeldahl method. For two organic standard materials studied, the Dumas method gave better accuracy. Standard deviation for both methods on these organic standards was poorer than for the feed materials, and further study is recommended.

Temperature Dependences in the O + OH → O2 + H Reaction. Quasiclassical Trajectory Calculation

1993 ◽  
Vol 58 (2) ◽  
pp. 234-243 ◽  
Author(s):  
Viliam Klimo ◽  
Martina Bittererová ◽  
Stanislav Biskupič ◽  
Ján Urban ◽  
Miroslav Micov
Keyword(s):  
Temperature Dependence ◽  
Energy Surface ◽  
Analytical Form ◽  
Mean Values ◽  
Quantum Numbers ◽  
Mean Lifetime ◽  
Temperature Dependences ◽  
Quasiclassical Trajectory Calculation ◽  
The Mean ◽  
Combustion Processes

The reaction O + OH → O2 + H in conditions of combustion of hydrocarbons and polymers was modelled by using the method of quasiclassical trajectories. The potential energy surface was determined by the multiconfiguration interaction method and fitted with the analytical form of the extended LEPS function. Attention was paid to the mean values of the vibrational and rotational quantum numbers of O2 molecules and their temperature dependence. The temperature dependence of the mean lifetime of the OOH collision complex was also examined. The calculated rate constants were analyzed and compared with the experimental data over the temperature region of the combustion processes.

Report of Ad Hoc Committee on Vitamin D Methodology, AOAC

1975 ◽  
Vol 58 (2) ◽  
pp. 330-332
Author(s):  
Forrest W Quackenbush ◽  
Daniel Banes ◽  
Philip H Derse
Keyword(s):  
Maleic Anhydride ◽  
Chemical Method ◽  
Ad Hoc ◽  
Collaborative Study ◽  
Mean Values ◽  
Biological Tests ◽  
Aoac Official ◽  
The Mean ◽  
Biological Methods ◽  
Good Agreement

Abstract In a collaborative study 6 samples of vitamin D3 resins were analyzed chemically by 9 laboratories and tested biologically by 3 laboratories to determine whether there exists a discrepancy between chemical and biological methods of measuring potency of these materials. The chemical methods employed saponification with and without subsequent maleic anhydride treatment. The biological method was the AOAC official final action rat assay, 39.149–39.162. The results showed good agreement between laboratories in the chemical analysis and relatively poor agreement in the biological tests. However, based upon the mean values as reported by the different laboratories, the chemical method employing saponification alone consistently overestimated biopotency, whereas the chemical method including maleic anhydride treatment gave results which averaged much closer to the mean biopotency values. There was no evidence that maleic anhydride treatment reduced values significantly below biopotency values.

Insight into neutron focusing: the out-of-focus condition

2013 ◽  
Vol 46 (5) ◽  
pp. 1361-1371 ◽  
Author(s):  
B. Hammouda ◽  
D. F. R. Mildner ◽  
A. Brûlet ◽  
S. Desert
Keyword(s):  
Standard Deviation ◽  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Neutron Wavelength ◽  
Focus Condition ◽  
The Mean ◽  
The Individual ◽  
Multiple Holes ◽  
Good Agreement

Neutron focusing leads to significant gains in flux-on-sample in small-angle neutron scattering and very small angle neutron scattering instruments. Understanding the out-of-focus condition is necessary for less than optimal conditions such as for short instruments and low neutron wavelengths. Neutron focusing is investigated using a three-pronged approach. The three methods are analytical calculations, resolution measurements and computer simulations. A source aperture containing a single small-size hole and a sample aperture containing multiple holes are used to produce multiple spots on the high-resolution neutron detector. Lens focusing elongates off-axis spots in the radial direction. The standard deviation for the size of each spot is estimated using these three approaches. Varying parameters include the neutron wavelength, the number of focusing lenses and the location of holes on the sample aperture. Enough agreement for the standard deviation of the individual neutron beams was found between the calculations and the measurements to give confidence in this approach. Good agreement was found between the standard deviations obtained from calculations and simulations as well. Excellent agreement was found for the mean location of these individual spots.

scholarly journals Fourth ventricle computed tomography indexes: standardisation and characteristics in neurocysticercosis

2002 ◽  
Vol 60 (2A) ◽  
pp. 211-218 ◽  
Author(s):  
Svetlana Agapejev
Keyword(s):  
Computed Tomography ◽  
Standard Deviation ◽  
Fourth Ventricle ◽  
Control Group ◽  
Mean Values ◽  
Lateral Ventricles ◽  
The Mean ◽  
Ventricular Shunting

OBJECTIVES: to propose standardisation of fourth ventricle dimensions and to study its characteristics in neurocysticercosis. METHOD: a control group (CG) constituted by 114 individuals with normal CT, and 80 patients with neurocysticercosis composed the group with neurocysticercosis (GN). Measures of the inner cranial diameter (Cr), fronto-polar distance between both lateral ventricles (FP), antero-posterior (AP) and latero-lateral (LL) fourth ventricle width based the standardisation of six indexes. RESULTS: AP/Cr, AP/LL and AP/FP were the more discriminative indexes, presenting in CG the mean values of 0.063, 0.267 and 0.582, respectively. The indexes in GN had values statistically higher than in CG. From GN, 51patients had increased indexes values above 2 standard deviation of the CG mean. AP/Ll was > or = 1 in 95% of patients with ventricular shunting and in 88% with depression. It also occurred in 73% patients with satisfactory follow-up and in everybody who died. CONCLUSION: AP/Cr, AP/LL and AP/FP may represent fourth ventricle dimensions.

scholarly journals Comparison of Four Radiographic Angular Measures of Lumbar Lordosis

2018 ◽  
Vol 09 (03) ◽  
pp. 298-304 ◽  
Author(s):  
Francis Osita Okpala
Keyword(s):  
Standard Deviation ◽  
Lumbar Lordosis ◽  
Joint Angle ◽  
Mean Values ◽  
Normal Individuals ◽  
Wide Range ◽  
Normal Mean ◽  
The Mean ◽  
Range Of Values

ABSTRACT Background: Several attempts (radiographic and nonradiographic) have been made to measure the lumbar lordosis (LL), but the results differ substantially as investigators have used different parameters. Radiography is the gold standard, and the methods include lumbosacral angle (LSA), lumbosacral joint angle (LSJA), Cobb angle, and tangential radiologic assessment of LL (TRALL) angle. The traditional method, the Cobb technique, has a wide range of normal mean values, with a large standard deviation. Using a more reliable radiographic angle will hopefully simply and standardize LL measurement in the diagnosis, treatment, and follow-up of patients. Aim: To compare in normal individuals with fully developed LL the LSA, LSJA, TRALL, and Cobb angles, by determining (a) if any correlation exists between them and (b) the most reliable measures of LL, based on, least (i) number of measurement lines, (ii) range of values, (iii) mean, (iv) standard deviation, and (v) variance. Materials and Methods: The four angles were retrospectively measured in each supine lateral lumbosacral radiograph of 100 males and 100 females, aged 15 years and above. Data were analyzed with IBM SPSS Statistics 23.0 (NY, USA); P < 0.05 was considered statistically significant. Results: No correlation existed between the mean values of the four angles, and in each angle, there was no male-versus-female correlation. LSJA had the best reliability criteria for LL measurement. Conclusion: The mean LSA, LSJA, TRALL, and Cobb angles have no significant Pearson's correlation, and of the four angular measures of LL, LSJA was the most reliable.

Statistical Analysis of Homogeneous Systems of Polar Coordinates

1975 ◽  
Vol 26 ◽  
pp. 469
Author(s):  
E. Proverbio ◽  
S. Uras
Keyword(s):  
Statistical Analysis ◽  
Standard Deviation ◽  
Polar Coordinates ◽  
Mean Values ◽  
Homogeneous Systems ◽  
The Mean

AbstractIn 1972, Proverbio and Quesada compiled a list of seven homogeneous systems of polar coordinates expressed in tenths of years adopted by different authors. In the paper, the authors try to determine the internal correlation of the different systems of coordinates so as to represent the precision of each series for different frequency ranges. The analysis of the standard deviation of the raw residuals of the differences between the coordinates of each series and the mean values from the smoothed curve of the residuals provided further information about the accuracy of the same series of polar coordinates.

Statistical analysis of wind resource and energy potential assessment of Quaidabad site, Sindh Pakistan

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Zahid Hussain Hulio ◽  
Gm Yousufzai ◽  
Wei Jiang
Keyword(s):  
Standard Deviation ◽  
Wind Speed ◽  
Energy Density ◽  
Wind Shear ◽  
Economic Assessment ◽  
Energy Potential ◽  
Content Type ◽  
Mean Values ◽  
The Mean ◽  
Wind Resource

Purpose Pakistan is an energy starving country that needs continuous supply of energy to keep up its economic speed. The aim of this paper is to assess the wind resource and energy potential of Quaidabad site for minimizing the dependence on fuels and improving the environment. Design/methodology/approach The Quaidabad site wind shear coefficient and turbulence intensity factor are investigated. The two-parameter k and c Weibull distribution function is used to analyze the wind speed of site. The standard deviation of the site is also assessed for a period of a year. The wind power density and energy density are assessed for a period of a year. The economic assessment of energy/kWh is investigated for selection of appropriate wind turbine. Findings The mean wind shear coefficient was observed to be 0.2719, 0.2191 and 0.1698 at 20, 40 and 60 m, respectively, for a period of a year. The mean wind speed is found to be 2.961, 3.563, 3.907 and 4.099 m/s at 20, 40, 60 and 80 m, respectively. The mean values of k parameters were observed to be 1.563, 2.092, 2.434 and 2.576 at 20, 40, 60 and 80 m, respectively, for a period of a year. The mean values of c m/s parameter were found to be 3.341, 4.020, 4.408 and 4.625 m/s at 20, 40, 60 and 80 m, respectively, for a period of a year. The major portion of values of standard deviation was found to be in between 0.1 and 2.00 at 20, 40, 60 and 80 m. The wind power density (W/m2) sum total values were observed to be 351, 597, 792 and 923 W/m2 at 20, 40, 60 and 80 m, respectively, for a period of a year. The mean coefficient of variation was found to be 0.161, 0.130, 0.115 and 0.105 at 20, 40, 60 and 80 m, respectively. The sum total energy density was observed to be 1,157, 2,156, 2,970 and 3,778 kWh/m2 at 20, 40, 60 and 80 m, respectively. The economic assessment is showing that wind turbine E has the minimum cost US$0.049/kWh. Originality/value The Quaidabad site is suitable for installing the utility wind turbines for energy generation at the lowest cost.

Variability of resting respiratory drive and timing in healthy subjects

1988 ◽  
Vol 65 (1) ◽  
pp. 309-317 ◽  
Author(s):  
M. J. Tobin ◽  
M. J. Mador ◽  
S. M. Guenther ◽  
R. F. Lodato ◽  
M. A. Sackner
Keyword(s):  
Standard Deviation ◽  
Healthy Subjects ◽  
Breathing Pattern ◽  
Respiratory Drive ◽  
Inspiratory Time ◽  
Mean Values ◽  
Coefficients Of Variation ◽  
The Mean ◽  
Older Subjects ◽  
Young Subjects

Studies of breathing pattern have focused primarily on changes in the mean values of the breathing pattern components, whereas there has been minimal investigation of breath-to-breath variability, which should provide information on the constancy with which respiration is controlled. In this study we examined the variability of breathing pattern both on a breath-to-breath and day-to-day basis by calculating the coefficient of variation (i.e., the standard deviation expressed as a percentage of the mean). By examining breath-to-breath data, we found that the coefficients of variation of tidal volume (VT) and fractional inspiratory time (TI/TT, an index of timing) obtained with an inductive plethysmograph and spirometer were within 1% of each other. Examination of breath-to-breath variability in breathing pattern over a 15-min period in 65 subjects revealed large coefficients of variation, indicating the need to base calculations on a relatively large number of breaths. Less breath-to-breath variability was observed in respiratory frequency [f, 20.8 +/- 11.5% (SD)] and TI/TT (17.9 +/- 6.5%) than in VT (33 +/- 14.9%) and mean inspiratory flow (VT/TI, an index of drive; 31.6 +/- 12.6%; P less than 0.0001). Older subjects (60-81 yr) displayed greater breath-to-breath variability than young subjects (21-50 yr). Use of a mouthpiece did not affect the degree of variability.(ABSTRACT TRUNCATED AT 250 WORDS)

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