Definite Critical Value Research Articles

Charged Quasinormal Modes and Dynamical Property of Black Hole with Global Monopole in de Sitter Spacetime

According to the basic rules of finite difference method,we calculate massive charged scalar field quasinormal modes of Reissner-Nordstrom-de Sitter Black Hole with a global monopole, which shows that when electronic quantity of scalar field e is comparatively small, all the factors including angular quantum number, the mass of scalar field, the size of horizon and the breaking scale will influence the frequency spectrum of quasinormal modes. When e is more than some definite critical value, second-order transition will appear and after that the curve of frequency spectrum rises, the black hole is no longer steady, which means when e is greater than some definite critical value, the structure of black hole can be changed. While the size of angular quantum number and breaking scale will influence the happening time of second-order transition. When breaking scale is less than some definite critical value, the second-order transition can be vanished.

INTERACTION BETWEEN THE 30° PARTIAL DISLOCATION AND HEX-VACANCY IN SILICON

The molecular dynamics (MD) method is used to investigate the interaction between the 30° partial dislocation and hex-vacancy (V6) in Si . The interaction processes are described in detail and compared with the prior results of mono-vacancy (V1) and di-vacancy (V2). It is found that dislocations are pinned by V6when the shear stresses are smaller than a definite critical value τc. It illustrates that the encountered two segments beside vacant sites parallel each other or annihilate. Moreover, it is shown that the critical shear stress τcis mainly determined by both the migration barrier of kink and the volume of vacancy. Although V6cannot make dislocations move faster due to the present small models, it may lower the dislocation density in certain conditions due to the pinning effect.

How diffraction affects the propagation of ultrashort optical pulses in isotropic insulators

The "averaged Lagrangian method" is used along with the paraxial and aberration-free approximations to investigate how diffraction affects the propagation of ultrashort optical pulses in an isotropic insulator. It is shown that diffraction is capable of compensating the self-focusing phenomenon if the number of vibrations contained in a pulse exceeds a definite critical value. © 2004 Optical Society of America

Coalescence of oil drops on the skeleton of a porous medium in filtering a water-oil mixture

Two mathematical models of filtration coalescence of oil drops when a water-oil mixture moves through a porous material are proposed. In the first model, coalescence is interpreted as the process of sorption, i.e., the accumulation of the oil phase on the pore surface up to a definite critical value above which the larger drops involved by a filtration flow stall. The second model assumes that the motion of the sorbed oil and the entire mixture obeys the generalized Darcy laws.

A new method for film deposition in the discharge of target metal vapour

A new method for generation of a discharge in its own metal vapour of an r.f.-excited electrode is described. The method is based on the r.f. plasma jet (RPJ) system utilizing a small size r.f. nozzle in which a hollow cathode-type discharge is generated. The nozzle outlet (target) is sputtered and/or evaporated by the ion bombardment from the jet discharge. The power density at the nozzle outlet reaches the order of hundreds of watts per square centimetre even at reasonably low r.f. power supply levels (above 100 W). A dense plasma containing a large amount of the nozzle metal ions can be generated inside the nozzle. Depending on the nozzle material, at a definite critical value of the r.f. power the discharge character can change to a particular kind of arc (RPJ arc) in which metal ejection inside the self-heated nozzle is sufficient to generate a sustained discharge without any auxiliary gas. Experiments indicate that the generation of the RPJ arc can be considered as a combination of a distributed discharge (diffuse) arc and a high voltage arc. Optical emission spectra from an Mg RPJ generated plasma exhibit only Mg emission lines and Mg film growth rate reaches values above 4 μm min −1. Conditions for generation of self-sustained discharges in Ti and Cu nozzles are also discussed. The effect of the nozzle geometry on the generation of stable self-sustained discharges for deposition of thin films is explained. In most cases an enhanced thermionic electron emission from the metallic surface contributes to a positive feedback to maintain the dense metal vapour plasma discharge. Deposition of Ti films in a plasma containing Ti vapours, Ti + ions and low partial pressure of Ar at regimes close to the RPJ arc is described.

The Fine Particles Residence in a Powder-Particle Fluidized Bed.

Residence time distribution of fine particles in a powder-particle fluidized bed was measured by using batch feeding of the fine particles. The effects of the initial fine particle concentration and the size of fine particles on the residence time distribution and on the amount of fine particles remaing in the bed were described. When the initial fine particles concentration was greater than a definite critical value, the initial elutriation rate of fine particles remained constant and equal to a certain limit value. For particles as small as 1 μm, almost all fine partices remained in the bed after 1h operation.

Asymptotic theory of the occurrence of recirculation zones in an axisymmetric wake under the influence of an adverse pressure gradient

An integrodifferential equation is obtained which describes the process of formation of recirculation zones near the axis of a thin axisymmetric wake in an incompressible fluid. The equation contains a parameter which characterizes the degree of influence of an adverse pressure gradient. It is shown that for values of the parameter less than a definite critical value there exist two different steady solutions, and for values exceeding the critical one there are no steady solutions.

Influence of the branching of isocyanate prepolymers on their rheological properties

It is shown that changes in the viscosity properties of isocyanate prepolymers during their high temperature synthesis are due to allophanate formation. The increasing degree of prepolymer branching leads, at a definite critical value, to a marked increase in the initial viscosity owing to the formation of a structural network.

The effects of oligomycin on energy metabolism and cation transport in slices of rat liver Inhibition of oxidative phosphorylation as the primary action

1. In slices of rat liver, oligomycin inhibited the net transport of Na + and K + by a maximum of 30% and endogenous respiration by 25%. These effects were not increased by a number of modifications in the incubation conditions. 2. Mitochondria isolated from the slices after incubation showed respiratory control ratios that were somewhat less than in mitochondria from fresh liver, but state 3 respiration retained normal sensitivity to oligomycin. 3. Low concentrations of oligomycin or cyanide reduced respiration and ATP levels of the slices but did not affect ion transport unless these levels fell below a definite critical value. In contrast, ouabain and atractyloside each caused substantial degrees of transport inhibition at ATP levels which were in excess of the critical value. 4. High concentrations of cyanide and oligomycin reduced ATP contents maximally by 90% and 65%, respectively. Studies of lactate production, and of the effects of arsenite on respiration and ATP levels, suggested that substrate-level phosphorylation in the citric-acid cycle was the major source of the oligomycin-resistant ATP synthesis. 5. The results suggest that oligomycin acts in the liver slices primarily as an inhibitor of oxidative phosphorylation, and that this is the cause of the partial inhibition of ion transport. The oligomycin-resistant ion-transporting activity is consistent with the persisting level of ATP synthesis.

Static displacements and shear instability of solid solution crystal lattice

The well-known phenomenological Hume-Rothery criterion of solubility in substitutional solid solutions is grounded within the scope of the microscopic theory (selfconsistent pseudoharmonic approximation). The shear instability is shown to arise when the static displacements exceed a definite critical value

TIG溶接用タングステン電極の性質

In this paper, the author intends to determine the current capacity and consumption of tungsten electrode in TIG arc welding for the purpose of establishing the standard (JIS) of the electrode.From this work, the following conclusions are obtained :(1) The current capacity of pure tungsten electrode under DCSP depends on Joule's heat and consequently on the stick-out length of electrode, and is formulated by experiment as Im=220× (α/le×102)3/4, where a is the cross section of electrode in cm2 and le is the stick-out length of. electrode in cm. The current capacity of thoriated tungsten in argon shielded DCSP arc is rather a little less than that of pure tungsten.(2) The DCRP current capacity has not a definite critical value, but is determined from a practial standpoint.(3) The failure of electrode due to over current in the AC TIG arc occurs in two ways ; that is, of S.P. type in smaller diameter electrode and of R.P. type in larger diameter electrode. The AC capacity depends largely on the amount of DC component, and their relation is given by Im=Im0/(1-αPd), where Im0 is the maximum allowable current in the case of balanced AC, Pd is the ratio of DC component to effective value of AC component and a is a theoretically given coefficient. The AC capacity of thoriated tungsten is considerably larger than that of pure tungsten.(4) From careful measurements using water-cooled Cu anode or aluminum plate as a work piece and preventing start spattering, the electrode consumption under DCSP steady arc is found to be a few mg/30 min. and seems to be caused through pure evaporation. The electrode consumption for AC arc under the same condition is 2 to 3 times the value mentioned above.(5) For, the arc when using steel plate as base electrode, the consumption is nearly 10 times that for DCSP arc with water cooled Cu anode, and especially in the case of the AC arc successive spattering sometimes accompanies.(6) At the start of DCSP arc, the spattering of electrode is caused when applying nearly maximum allowable current suddenly to pure, tungsten which was once used. Start spattering is not caused by (a) thoriated tungsten (b) pure, virgin tungsten, (c) arc starting with smaller current.(7) The start spattering is found to occur succeedingly for about 1/4sec. following the arc ignition, and seems to be caused by the cavity formed at the tip of electrode and the thermal shock.

Photometric Study of Bacteriophage Action

Krueger and Northrop were the first to undertake the study of bacteriophage action from a quantitative point of view. Based on extremely elaborate technical procedures, involving frequent and separate enumeration of bacteria and of bacteriophage throughout each experiment, they concluded that production of phage was proportional to a power of bacterial growth and that lysis set in almost explosively at the moment when phage/bacteria ratio attained a definite critical value. It would appear that according to their result the time required for lysis of a given bacterial concentration is proportional to the dilution of phage. Other conditions being constant, the strength of any 2 phages can be compared by noting the relative length of time necessary for reduction of a constant concentration of bacteria to an arbitrary end point. The present paper is not intended to add anything new to the mechanism of bacteriophage action, but rather to present an accurate though considerably simpler device for attacking the problem from the same viewpoint. The apparatus used is a Pulfrich photometer which works on the principle of the Tyndall phenomenon, so that for a given bacterium, the number of organisms per cc. can be read off directly and quickly and is expressed in terms of percentage of a given standard. Very minute particles, namely, phage or protein particles, liberated during the process of dissolution of bacteria present a very weak Tyndall phenomenon and do not, therefore, affect the readings. Provided the bacterial suspension is not so thick as to interfere with penetration of light, the accuracy of readings obtained approached ±0.5% of the given standard, disregarding slight variations in the size and thickness of the tubes used. The phage used throughout the experiment is from d'Herelle's laboratory and has been in our stock since 1927.

LVI.Theory of collision of spheres of soft metals

Abstract Beginning with the fact that when two spheres of soft metal collide, permanent deformation is produced when the velocity of approach exceeds a definite critical value ; and with the aid of the assumption that over the permanently deformed region the pressure remains constant at all points, a theory of collision is worked out. This theory is found capable of accounting for the variation with the velocity of approach v, of 1. (a) The duration of contact t of the spheres,2. (b) the diameters d of the permanent deformations, and3. (c) the coefficient of restitution e. The detailed character of the experimental results is explained. At high speeds of approach, the duration of contact and the quantity e 2 v 2 are linear functions of 1/v and of v respectively; while it appears that a definite quantity of energy is required per unit mass of the material apparently removed during deformation. A latent heat of deformation for a number of substances is calculated. Finally, the influence of viscous resistance and of time-effects, such as the elastic after-effect etc., is considered.