On the Length of Two-Dimensional Contractions

1966 ◽  
Vol 70 (666) ◽  
pp. 673-675 ◽  
Author(s):  
W. T. F. Lau
Keyword(s):  
Mean Value ◽  
List Type ◽  
Two Dimensional ◽  
Type Number ◽  
Asymptotic Value ◽  
Centre Line ◽  
Boundary Slope

In a recent paper, Gibbings has made an interesting comparison of the length of two-dimensional contractions based on three criteria, namely:(1)the rapidity with which the boundary slope approaches its zero value;(2)the rapidity with which the centre-line velocity approaches its asymptotic value; and(3)the degree of uniformity of the velocity expressed as a percentage of its mean value.

On the Effective “Length” of Two-Dimensional Contracting Ducts

1966 ◽  
Vol 70 (666) ◽  
pp. 676-676 ◽  
Author(s):  
J. C. Gibbings
Keyword(s):  
Effective Length ◽  
Two Dimensional ◽  
Asymptotic Value ◽  
Points Of Interest ◽  
Centre Line ◽  
Boundary Slope

The note by W. T. F. Lau upon the effective “length” of two-dimensional contracting ducts has raised further points of interest.Lau's paper presents three different criteria which can control a contraction length. Of these three, the second and third, that respectively are based upon the approach of the centre-line velocity to its asymptotic value and upon the approach of the flow to uniformity, were compared in ref. 1. The first criterion that is based upon the approach of the boundary slope to zero is not in general identical with the second.

A process with chain dependent growth rate

1970 ◽  
Vol 7 (03) ◽  
pp. 699-711 ◽  
Author(s):  
Julian Keilson ◽  
S. Subba Rao
Keyword(s):  
Growth Rate ◽  
Markov Chain ◽  
Continuous Time ◽  
List Type ◽  
Two Dimensional ◽  
Type Number ◽  
Finite Markov Chains ◽  
Dependent Growth ◽  
Irreducible Markov Chain ◽  
Independent Poisson Process

Additive processes on finite Markov chains have been investigated by Miller ([8], [9]), Keilson and Wishart ([2], [3], [4]) and by Fukushima and Hitsuda [1]. These papers study a two-dimensional Markov Process {X(t),R(t)} whose state space isR1× {1, 2, ···,R} characterized by the following properties:(i)R(t) is an irreducible Markov chain on states 1,2, …,R governed by atransition probability matrixBo= {brs}.(ii)X(t) is a sumof random increments dependent on the chain, i.e., if the ith transition takes the chain from state r to state s, then the incrementhas the distribution(iii)Nt, is t in discrete time while in the continuous time case Nt, might be an independent Poisson process.

A process with chain dependent growth rate

1970 ◽  
Vol 7 (3) ◽  
pp. 699-711 ◽  
Author(s):  
Julian Keilson ◽  
S. Subba Rao
Keyword(s):  
Growth Rate ◽  
Markov Chain ◽  
Continuous Time ◽  
List Type ◽  
Two Dimensional ◽  
Type Number ◽  
Finite Markov Chains ◽  
Dependent Growth ◽  
Irreducible Markov Chain ◽  
Independent Poisson Process

Additive processes on finite Markov chains have been investigated by Miller ([8], [9]), Keilson and Wishart ([2], [3], [4]) and by Fukushima and Hitsuda [1]. These papers study a two-dimensional Markov Process {X(t), R(t)} whose state space is R1 × {1, 2, ···, R} characterized by the following properties: (i)R(t) is an irreducible Markov chain on states 1,2, …,R governed by atransition probability matrix Bo = {brs}.(ii)X(t) is a sum of random increments dependent on the chain, i.e., if the ith transition takes the chain from state r to state s, then the increment has the distribution (iii)Nt, is t in discrete time while in the continuous time case Nt, might be an independent Poisson process.

scholarly journals Quantitative Two-Dimensional Classifications of Low Dispersion Objective Prism Spectra

1978 ◽  
Vol 80 ◽  
pp. 29-32
Author(s):  
Th. Schmidt-Kaler
Keyword(s):  
List Type ◽  
Spectral Features ◽  
Two Dimensional ◽  
Type Number ◽  
Comparison Spectrum ◽  
Stellar Spectra ◽  
Quantitative Measurements ◽  
Light Losses ◽  
Objective Prism ◽  
Low Dispersion

The objective prism (or grating) is the most efficient stellar spectrograph since it suffers no light losses at a slit and - compared to a slit spectrograph - only small losses in the camera optics. However, objective prism spectra have two principal disadvantages:(1)the spectral resolution (and consequently the sharpness of spectral features) depends on the seeing, which may vary from plate to plate.(2)quantitative measurements are difficult because of the difficulty in obtaining an exact photographic calibration; no comparison spectrum can be placed near the stellar spectra.

Solar Corona Investigation by the Coronal Line Photometer at Lomnický Peak

1994 ◽  
Vol 144 ◽  
pp. 431-434
Author(s):  
M. Minarovjech ◽  
M. Rybanský
Keyword(s):  
Solar Corona ◽  
Time Resolution ◽  
Active Regions ◽  
High Time ◽  
High Time Resolution ◽  
List Type ◽  
Type Number ◽  
Coronal Line ◽  
Global Cycle

AbstractThis paper deals with a possibility to use the ground-based method of observation in order to solve basic problems connected with the solar corona research. Namely:1.heating of the solar corona2.course of the global cycle in the corona3.rotation of the solar corona and development of active regions.There is stressed a possibility of high-time resolution of the coronal line photometer at Lomnický Peak coronal station, and use of the latter to obtain crucial observations.

The LDE-Type Flare Occurrence (1969-1993)

1994 ◽  
Vol 144 ◽  
pp. 279-282
Author(s):  
A. Antalová
Keyword(s):  
Time Series ◽  
Fourier Analysis ◽  
Sunspot Cycle ◽  
List Type ◽  
Type Number ◽  
Solar Cycles ◽  
Type Iv ◽  
Long Duration ◽  
Cycle Maximum ◽  
Flare Index

AbstractThe occurrence of LDE-type flares in the last three cycles has been investigated. The Fourier analysis spectrum was calculated for the time series of the LDE-type flare occurrence during the 20-th, the 21-st and the rising part of the 22-nd cycle. LDE-type flares (Long Duration Events in SXR) are associated with the interplanetary protons (SEP and STIP as well), energized coronal archs and radio type IV emission. Generally, in all the cycles considered, LDE-type flares mainly originated during a 6-year interval of the respective cycle (2 years before and 4 years after the sunspot cycle maximum). The following significant periodicities were found:• in the 20-th cycle: 1.4, 2.1, 2.9, 4.0, 10.7 and 54.2 of month,• in the 21-st cycle: 1.2, 1.6, 2.8, 4.9, 7.8 and 44.5 of month,• in the 22-nd cycle, till March 1992: 1.4, 1.8, 2.4, 7.2, 8.7, 11.8 and 29.1 of month,• in all interval (1969-1992):a)the longer periodicities: 232.1, 121.1 (the dominant at 10.1 of year), 80.7, 61.9 and 25.6 of month,b)the shorter periodicities: 4.7, 5.0, 6.8, 7.9, 9.1, 15.8 and 20.4 of month.Fourier analysis of the LDE-type flare index (FI) yields significant peaks at 2.3 - 2.9 months and 4.2 - 4.9 months. These short periodicities correspond remarkably in the all three last solar cycles. The larger periodicities are different in respective cycles.

Discussion following the presentation by F. Deubner

1977 ◽  
Vol 36 ◽  
pp. 69-74
Keyword(s):  
List Type ◽  
The Sun ◽  
Type Number ◽  
Harmonic Motion ◽  
Locally Excited ◽  
Long Period ◽  
Coherent Wave ◽  
Short Period ◽  
Global Modes

The discussion was separated into 3 different topics according to the separation made by the reviewer between the different periods of waves observed in the sun :1) global modes (long period oscillations) with predominantly radial harmonic motion.2) modes with large coherent - wave systems but not necessarily global excitation (300 s oscillation).3) locally excited - short period waves.

Prominences and Solar Activity

1979 ◽  
Vol 44 ◽  
pp. 357-372
Author(s):  
Z. Švestka
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
List Type ◽  
Type Number ◽  
Flare Loops ◽  
Filament Activation

The following subjects were discussed:(1)Filament activation(2)Post-flare loops.(3)Surges and sprays.(4)Coronal transients.(5)Disk vs. limb observations.(6)Solar cycle variations of prominence occurrence.(7)Active prominences patrol service.Of all these items, (1) and (2) were discussed in most detail and we also pay most attention to them in this report. Items (3) and (4) did not bring anything new when compared with the earlier invited presentations given by RUST and ZIRIN and therefore, we omit them.

A New System For Optomanual Semiautomatic Quantitative Image Analysis

1977 ◽  
Vol 35 ◽  
pp. 210-211
Author(s):  
H.P. Rohr
Keyword(s):  
Image Analysis ◽  
Volume Density ◽  
List Type ◽  
Distribution Analysis ◽  
Type Number ◽  
Point Counting ◽  
Human Eye ◽  
Quantitative Image ◽  
Point Density ◽  
Electronic Counting

Today, in image analysis the broadest possible rationalization and economization have become desirable. Basically, there are two approaches for image analysis: The image analysis through the so-called scanning methods which are usually performed without the human eye and the systems of optical semiautomatic analysis completely relying on the human eye.The new MOP AM 01 opto-manual system (fig.) represents one of the very promising approaches in this field. The instrument consists of an electronic counting and storing unit, which incorporates a microprocessor and a keyboard for choice of measuring parameters, well designed for easy use.Using the MOP AM 01 there are three possibilities of image analysis:the manual point counting,the opto-manual point counting andthe measurement of absolute areas and/or length (size distribution analysis included).To determine a point density for the calculation of the corresponding volume density the intercepts lying within the structure are scanned with the light pen.

Hydration Chamber for Jeolco 200 Kv Microscope

1970 ◽  
Vol 28 ◽  
pp. 542-543
Author(s):  
V. R. Matricardi ◽  
G. G. Hausner ◽  
D. F. Parsons
Keyword(s):  
Electron Microscope ◽  
Water Vapor ◽  
Vapor Pressure ◽  
Pressure Gradient ◽  
Room Temperature ◽  
List Type ◽  
Type Number ◽  
Equilibrium Vapor Pressure

In order to observe room temperature hydrated specimens in an electron microscope, the following conditions should be satisfied: The specimen should be surrounded by water vapor as close as possible to the equilibrium vapor pressure corresponding to the temperature of the specimen.The specimen grid should be inserted, focused and photo graphed in the shortest possible time in order to minimize dehydration.The full area of the specimen grid should be visible in order to minimize the number of changes of specimen required.There should be no pressure gradient across the grid so that specimens can be straddled across holes.Leakage of water vapor to the column should be minimized.

Sign in / Sign up

Export Citation Format

Share Document