Physical analysis of the fleece of sheep for biological purposes. II. Estimation of the number and mean diameter of wool fibres from a cast of their cross-section

1951 ◽  
Vol 2 (2) ◽  
pp. 195 ◽  
Author(s):  
LT Wilson
Keyword(s):  
Cross Section ◽  
Unit Area ◽  
Physical Analysis ◽  
Mean Diameter ◽  
The Mean ◽  
The Cross ◽  
Limits Of Error

A technique has been developed for making a cast of the cross-section of a bundle of wool fibres under defined packing conditions. By counting the fibre impressions per unit area in representative portions of the cast, both the total number of fibres and the mean diameter can be rapidly calculated within fairly close limits of error.

A measurement of the ionization cross-section of Ne + to Ne 2+ by electron impact

1963 ◽  
Vol 274 (1359) ◽  
pp. 546-551 ◽  
Keyword(s):  
Electron Energy ◽  
Cross Section ◽  
Ionization Cross Section ◽  
Incident Electron Energy ◽  
Ionization Cross ◽  
Maximum Value ◽  
Beam Method ◽  
The Cross ◽  
Semi Empirical ◽  
Limits Of Error

The crossed-beam method described by the authors in 1961 was used to measure the cross-section of Ne + in the reaction Ne + + e → Ne 2+ + 2 e . The cross-section increases linearly with electron energy near the threshold and attains a maximum value of 3·13 x 10 -17 cm 2 at 200 eV. The errors in the measurements were estimated to be less than ± 10% and the highest incident electron energy used was 1000 eV. A semi-empirical formula proposed by Drawin in 1961 describes the measured cross-section within the above limits of error when the two adjustable parameters take the values ξf 1 = 5·25 and f 2 = 0·70.

The determination of the cross sections for the reactions 27 Al( n , α ) and 56 Fe( n , p ) for 14 MeV neutrons by an absolute method

1966 ◽  
Vol 292 (1429) ◽  
pp. 180-192 ◽  
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Standard Error ◽  
Particle Method ◽  
Systematic Errors ◽  
Aluminium Foil ◽  
The Mean ◽  
The Cross ◽  
Experimental Values

Measurements of the cross sections for the reactions 27 Al( n , α ) 24 Na and 56 Fe( n, p ) 56 Mn for neutrons of energy 13.5 ± 0.1 MeV have been made by a radioactivation method. The neutron flux was determined by a variant of the 'associated particle’ method, in which the α -particles produced concurrently with the neutrons from the D + T reaction were estimated in terms of the volume of helium which accumulated when they were brought to rest in an aluminium foil. Cross section values obtained at 13.5 MeV were: for 27 Al( n , α ): 118.1 ± 6.0 mb : for 56 Fe( n, p ): 106.7 ± 4.7 mb. The errors quoted include both the standard error on the mean of the experimental values and an estimate of possible residual systematic errors. The excitation functions for both reactions in the energy region 13.5 to 14.8 MeV have also been investigated, in order to provide secondary cross section values over this range of energies. At 14.8 MeV the values found were: 27 Al( n , α )103.6 ± 5.5 mb; 56 Fe( n, p )96.7 ± 4.5 mb.

scholarly journals Monte Carlo Simulation of the Formation of Snowflakes

2005 ◽  
Vol 62 (5) ◽  
pp. 1529-1544 ◽  
Author(s):  
Ken-ichi Maruyama ◽  
Yasushi Fujiyoshi
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Standard Deviation ◽  
Cross Section ◽  
Collision Cross Section ◽  
Initial Distribution ◽  
Sphere Model ◽  
Aggregate Model ◽  
Mean Diameter ◽  
The Mean

Abstract A stochastic microphysical model of snow aggregation that combines a simple aggregation model with a Monte Carlo method was developed. Explicit treatment of the shape of individual snowflakes in the new model facilitates examination of the structure of snowflakes and the relationships between the parameters of the generated snowflakes, such as mass versus diameter, in addition to comparisons with observations. In this study, complexities in the shape of snowflakes are successfully simulated, and the understanding of the evolution of their size distribution is advanced. The mean diameter of snow particles evolves more rapidly in the aggregate model than in the sphere model. However, growth rates of the aggregates greatly depend on the collision section of particles in aggregation. The mean mass of snowflakes in the aggregate model grows more slowly than the mass in the sphere model when the sum of the particle cross section is used as the collision cross section. The mean mass grows more quickly when a circle is used whose radius is the sum of the radii of two particles. Sensitivity experiments showed that aggregation also depends on the mean and standard deviation of the initial distribution, and on the density of constituent particles.

Preparation of Ni-P-Al2O3 Composite Film on Mild Steel with High Resistance to Corrosion and Wear

2013 ◽  
Vol 750 ◽  
pp. 31-35
Author(s):  
Rong Guang Wang ◽  
Hiroki Sawada ◽  
Nan Wang ◽  
Jian Nie
Keyword(s):  
Mild Steel ◽  
Composite Film ◽  
Cross Section ◽  
Corrosion And Wear ◽  
Al2o3 Composite ◽  
Plating Method ◽  
Mean Diameter ◽  
The Mean ◽  
Plating Solution ◽  
Electroless Plating Method

The Ni-P-Al2O3 composite film was coated on mild steel of SS400 with electroless plating method. In this process, different sizes of Al2O3 particles and different blended amounts of Al2O3 particles into the plating solution were applied. From the surface and cross section observation, it is known that the Al2O3 particles were uniformly dispersed in the Ni-P alloy. The highest corrosion resistance and the highest wear resistance of the Ni-P-Al2O3 composite film were obtained when adding Al2O3 particles with the mean diameter of 0.05μm into the plating solution at the blended amount of 1.0g/L.

The initial dispersion of contaminant in Poiseuille flow and the smoothing of the snout

1976 ◽  
Vol 77 (3) ◽  
pp. 593-602 ◽  
Author(s):  
P. C. Chatwin
Keyword(s):  
Cross Section ◽  
Poiseuille Flow ◽  
Molecular Diffusion ◽  
Lateral Diffusion ◽  
Longitudinal Diffusion ◽  
Molecular Diffusivity ◽  
Discharge Velocity ◽  
Smoothing Process ◽  
The Mean ◽  
The Cross

In Poiseuille flow in a circular tube passive contaminant initially spread uniformly over the cross-section would be pulled out in a paraboloidal snout in the absence of any diffusive mechanism, and there would be a discontinuity in $\overline{C}$, the mean concentration over the cross-section, associated with the contaminant at the front of the snout. In reality molecular diffusion smooths out this snout in two ways: direct longitudinal diffusion and the interaction between lateral diffusion and advection. The effect of these two mechanisms is discussed, and determined for small values of κt/a2, where t is the time since injection, κ is the molecular diffusivity and a is the tube radius. For such values, important in many applications, the tube walls play no part in the smoothing process. It is shown that for $\kappa t/a^2 < 0.25(\overline{u}a/\kappa)^{-\frac{2}{3}}$, where $\overline{u}$ is the discharge velocity, the effect of longitudinal diffusion dominates over that of the interaction, which is, in turn, dominant for $\kappa t/a^2 > 2.5(\overline{u}a/\kappa)^{-\frac{2}{3}}$, when $\overline{C}$ is close to the form described by Lighthill (1966).

On the dispersion of a solute in a fluid flowing through a tube

1956 ◽  
Vol 235 (1200) ◽  
pp. 67-77 ◽  
Keyword(s):  
Diffusion Coefficient ◽  
Cross Section ◽  
Molecular Diffusion ◽  
Simultaneous Action ◽  
Mean Velocity ◽  
Molecular Diffusion Coefficient ◽  
Rate Of Growth ◽  
The Mean ◽  
The Cross ◽  
Dimension Characteristic

Sir Geoffrey Taylor has recently discussed the dispersion of a solute under the simultaneous action of molecular diffusion and variation of the velocity of the solvent. A new basis for his analysis is presented here which removes the restrictions imposed on some of the para­meters at the expense of describing the distribution of solute in terms of its moments in the direction of flow. It is shown that the rate of growth of the variance is proportional to the sum of the molecular diffusion coefficient, D , and the Taylor diffusion coefficient Ka 2 U 2 / D , where U is the mean velocity and a is a dimension characteristic of the cross-section of the tube. An expression for k is given in the most general case, and it is shown that a finite distribution of solute tends to become normally distributed.

scholarly journals The angular distribution of protons projected by fast neutrons

1937 ◽  
Vol 163 (913) ◽  
pp. 265-281 ◽  
Keyword(s):  
Angular Distribution ◽  
Binding Energy ◽  
Cross Section ◽  
Direct Evidence ◽  
Fast Neutrons ◽  
Proton Scattering ◽  
Potential Well ◽  
The Mean ◽  
The Cross ◽  
Square Hole

The nature of the interaction between neutron and proton has assumed great importance in modern nuclear theory, since it is now generally assumed that these two particles form the fundamental constituents of all nuclei. Little direct evidence exists, however, as to the nature of this interaction. The stable existence of the deuteron shows that the force between neutron and proton is attractive, and for purposes of calculation a “square hole” potential well has generally been assumed. With this model some success has been obtained* in correlating the magnitudes of a number of experimentally measurable quantities such as ( a ) the binding energy of the deuteron, ( b ) the total cross-section for neutron-proton scattering (Tuve and Hafstad 1936; Amaldi and Fermi 1936 a ), ( c ) the cross-section for photo­ electric disintegration of the deuteron (Chadwick and Goldhaber 1935), and ( d ) the cross-section for capture of neutrons by protons (Amaldi and Fermi 1936 b ). The interaction is not completely derivable from the above data, since the values of these quantities depend mainly upon r 2 V , where r is the mean radius and V is the depth of the potential hole.

scholarly journals On the viscous flow in metals, and allied phenomena

1910 ◽  
Vol 84 (567) ◽  
pp. 1-12 ◽  
Keyword(s):  
Viscous Flow ◽  
Cross Section ◽  
Elastic Limit ◽  
Unit Area ◽  
Lead Wire ◽  
Automatic Method ◽  
The Wire ◽  
The Law ◽  
The Cross ◽  
Hyperbolic Weight

It has been observed that for a lead wire, loaded well beyond the elastic limit, the extension after some time becomes proportional to the time, or the flow becomes viscous in character. The rate of this viscous flow varies with the load, and the following work was undertaken to investigate the law of this variation, and the phenomenon in general. Methods of Experiment. The Hyperbolic Weight . The experiments were all done on wires of the metal, and the preliminary observations were all made on lead. To suspend the wires, they were soldered into stout brass hooks. In the first rough experiments the extension registered itself on a clockwork-driven drum; these experiments showed that the rate of extension for a given load became constant for a time, but finally increased, and continued increasing. This is due to two causes: (1) As the wire stretches, the length of wire being experimented on at any moment increases. (2) As the wire stretches, the cross-section diminishes, and thus the load per unit area or stress increases. This is by far the more disturbing cause, since, as shown later, the rate increases much more rapidly with the stress than would be given by a linear law. To obviate this difficulty an automatic method of keeping the stress constant was devised.

A HREM study of the interfaces between TiO2 precipitates and the Al2O3 matrix in star sapphire

1992 ◽  
Vol 50 (1) ◽  
pp. 228-229
Author(s):  
S.Q. Xiao ◽  
A. H. Heuer ◽  
P. Pirouz
Keyword(s):  
Cross Section ◽  
Lattice Mismatch ◽  
Misfit Dislocations ◽  
Regular Array ◽  
Lattice Constants ◽  
Small Precipitate ◽  
S Matrix ◽  
The Matrix ◽  
The Mean ◽  
The Cross

The asterism, or star effect, present in star sapphire (Ti-doped A12O3) single crystals is known to arise from the needle-like rutile(r) (TiO2) precipitates in the sapphire(s) matrix. The specific orientation relationship between the precipitates and the matrix is {100}r//{0003}s and <011>r//<1010>s . In this work we report a HREM study of the rutile/sapphire interface.The cross-section perpendicular to the needle axis of a very small precipitate, which is coherent, or has just one misfit dislocation at its interface, is a rhombus; the precipitate/matrix interface (habit plane) is {111}r{1123}s. As the coherency break down and misfit dislocations are introduced into the interface, the shape of the cross-section becomes nearly square; the two orthogonal interfaces are {100}r//0003}s and {011}r//{1120}s. Larger precipitates show rectangular interfaces elongated along the {100}r//{0003}s interface (Fig.l). A regular array of misfit dislocations with Burger vector b = 1/3<0001>S are present at the {011}r//{1120}s interface, the mean distance between every two adjacent 1/3<0001>S misfit dislocations being 8.7 nm which compensates exactly the 5.9% lattice mismatch estimated from the lattice constants of these two structures. Similarly, a regular array of misfit dislocations with Burgers vector b = 1/3<1010>S at the {100}r//{0003}s interface compensates the 4.5% lattice mismatch at that interface.

Observations of nutritional and seasonal changes in the fleeces of some masham sheep

1956 ◽  
Vol 47 (2) ◽  
pp. 129-144 ◽  
Author(s):  
M. L. Byder
Keyword(s):  
Body Weight ◽  
Seasonal Changes ◽  
Unit Area ◽  
Sampling Time ◽  
Seasonal Fluctuations ◽  
Wool Production ◽  
Mean Diameter ◽  
The Mean ◽  
Poor Nutrition ◽  
Skin Samples

1. An experiment was carried out in summer when sheep do not normally shed their wool fibres to see if a poor diet would induce fibre shedding. Observations were then continued for a year to follow seasonal variations in the fleece.2. The two experimental sheep lost about a quarter of their body weight during the nutrition experiment. Measurement of areas tattooed in the skin showed that there was a reduction of about 5% in these areas.3. Histologieal observations of skin samples showed that there was very little fibre shedding during the nutrition experiment. This suggests that poor nutrition alone will not cause sheep to shed their fibres. More fibre shedding took place during the winter even though the sheep were well fed, suggesting a seasonal stimulus for shedding.4. ‘Brushes’ which are normally formed when fibres shed in primary follicles were also seen in secondary follicles.5. Observations were made during the nutrition experiment of the blood vessels in the skin and glycogen in the outer root sheaths of the follicles. No changes were seen in either the numbers of vessels, or the amount of glycogen present.6. The weight of wool produced per unit area per day was determined at each sampling time during the whole year. The experimental sheep behaved differently from the controls in their wool production during the nutrition experiment. Thereafter all sheep behaved the same, and seasonal fluctuations in wool production were found.7. The mean length and mean diameter of the wool produced was determined at each sampling time throughout the year.

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