scholarly journals Long-Term Evolution of Starspot and Chromospheric Activity and Short-Term Light Variability of HK Lacertae

1989 ◽  
Vol 104 (2) ◽  
pp. 135-138
Author(s):  
Katalin Olah
Keyword(s):  
Cycle Length ◽  
Periodic Variation ◽  
Short Term ◽  
Long Period ◽  
Chromospheric Activity ◽  
Term Evolution ◽  
Ubv Photometry ◽  
Light Variability ◽  
Photospheric Temperature

AbstractOn the basis of 11 years of UBV photometry the light and color variability of the long-period RS CVn binary HK Lac (KOIII) is discussed. From the U-B data, which reflect the chromospheric activity, a quasi-periodic variation with the cycle length of about 5.5 years is suspected. Less evidently, a 2.7 years long overall spot coverage cycle is seen from the V(max) data.No cyclic variation is found from the B-V data representing the photospheric temperature conditions, although there is an indication that the star was the reddest around 1985, when the chromospheric activity was in maximum.At that time, in late 1985, we observed the star on 6 nights in UBV color in order to detect short-term variability. Fluctuations up to 0.03 magn. on time scales of 20-30 minutes were likely present. The mplitude is the highest in U colour.

A dynamic and robust image processing based method for measuring the yarn diameter and its variation

2014 ◽  
Vol 84 (18) ◽  
pp. 1948-1960 ◽  
Author(s):  
Mohamed Eldessouki ◽  
Sayed Ibrahim ◽  
Jiři Militky
Keyword(s):  
High Speed ◽  
Dynamic Change ◽  
Effective Property ◽  
Periodic Variation ◽  
Short Term ◽  
Reasonable Time ◽  
Yarn Diameter ◽  
Fabric Structure ◽  
Robust Image

The yarn diameter is an effective property in determining fabric structure and processing settings. There are different systems of measuring the yarn diameter; among them is the image analysis of the yarn’s microscopic images. This method is considered to be more precise than other methods, but it is “static” in nature as it measures the property at scattered intervals and does not reflect the continuous variation of the yarn diameter. The goal of the current work is to measure the yarn diameter and its variation over a long length of yarn at fixed intervals to consider the “dynamic” change in the property. To achieve this goal, a high-speed camera (HSC) with a proper magnification was used to capture the images of the yarn and a new robust algorithm was developed to analyze the massive amount of yarn pictures in a reasonable time. The collected data for the yarn diameter were analyzed and compared to the results of the commercial Uster Evenness Tester IV. The results of the HSC were very comparable to the results of Uster and they were able to detect the short-term, the long-term, and the periodic variation of the yarn diameter.

Searching for the cycle period in chromospherically active stars

2019 ◽  
Vol 15 (S354) ◽  
pp. 120-122
Author(s):  
F. Villegas ◽  
R. E. Mennickent ◽  
J. Garcés
Keyword(s):  
Cycle Length ◽  
Variable Star ◽  
Line Emission ◽  
Cycle Period ◽  
Stellar Rotation ◽  
Convective Flows ◽  
Chromospheric Activity ◽  
Magnetic Cycles ◽  
First Time

AbstractThe detection and analysis of line emission of the CaII, H(396.8nm) and K(393.3nm) have confirmed the chromospheric activity of some single and binaries stars. This activity is associated to the presence of magnetic fields which in turn are produced by internal convective flows along with stellar rotation producing a long-term photometric cycle length related to the apparition and vanishing of superficial stellar spots. We present a photometric study of stars of the type RS CVn, Rotationally variable Star and BY Dra, that have shown evidence of chromospheric activity. The analysis of these measurements has allowed us to delimit periods of rotation. In addition, we have detected and measured the cycle length in some cases. It allows us to complement previous investigations and in some cases to determine for the first time the presence of a long photometric cycle, contributing to complement the link between rotation and magnetic cycles.

scholarly journals Spectral evolution of weakly nonlinear random waves: kinetic description versus direct numerical simulations

2018 ◽  
Vol 844 ◽  
pp. 766-795 ◽  
Author(s):  
Sergei Y. Annenkov ◽  
Victor I. Shrira
Keyword(s):  
Time Scale ◽  
Kinetic Equations ◽  
Wave Spectra ◽  
Kinetic Description ◽  
Spectral Evolution ◽  
Short Term ◽  
Weakly Nonlinear ◽  
Term Evolution ◽  
Integral Characteristics

Kinetic equations are widely used in many branches of science to describe the evolution of random wave spectra. To examine the validity of these equations, we study numerically the long-term evolution of water wave spectra without wind input using three different models. The first model is the classical kinetic (Hasselmann) equation (KE). The second model is the generalised kinetic equation (gKE), derived employing the same statistical closure as the KE but without the assumption of quasistationarity. The third model, which we refer to as the DNS-ZE, is a direct numerical simulation algorithm based on the Zakharov integrodifferential equation, which plays the role of the primitive equation for a weakly nonlinear wave field. It does not employ any statistical assumptions. We perform a comparison of the spectral evolution of the same initial distributions without forcing, with/without a statistical closure and with/without the quasistationarity assumption. For the initial conditions, we choose two narrow-banded spectra with the same frequency distribution and different degrees of directionality. The short-term evolution ($O(10^{2})$ wave periods) of both spectra has been previously thoroughly studied experimentally and numerically using a variety of approaches. Our DNS-ZE results are validated both with existing short-term DNS by other methods and with available laboratory observations of higher-order moment (kurtosis) evolution. All three models demonstrate very close evolution of integral characteristics of the spectra, approaching with time the theoretical asymptotes of the self-similar stage of evolution. Both kinetic equations give almost identical spectral evolution, unless the spectrum is initially too narrow in angle. However, there are major differences between the DNS-ZE and gKE/KE predictions. First, the rate of angular broadening of initially narrow angular distributions is much larger for the gKE and KE than for the DNS-ZE, although the angular width does appear to tend to the same universal value at large times. Second, the shapes of the frequency spectra differ substantially (even when the nonlinearity is decreased), the DNS-ZE spectra being wider than the KE/gKE ones and having much lower spectral peaks. Third, the maximal rates of change of the spectra obtained with the DNS-ZE scale as the fourth power of nonlinearity, which corresponds to the dynamical time scale of evolution, rather than the sixth power of nonlinearity typical of the kinetic time scale exhibited by the KE. The gKE predictions fall in between. While the long-term DNS show excellent agreement with the KE predictions for integral characteristics of evolving wave spectra, the striking systematic discrepancies for a number of specific spectral characteristics call for revision of the fundamentals of the wave kinetic description.

scholarly journals Long-term evolution is surprisingly predictable in lattice proteins

2013 ◽  
Vol 10 (82) ◽  
pp. 20130026 ◽  
Author(s):  
Michael E. Palmer ◽  
Arnav Moudgil ◽  
Marcus W. Feldman
Keyword(s):  
Natural Selection ◽  
Basins Of Attraction ◽  
Long Term Outcomes ◽  
Short Term ◽  
Term Selection ◽  
Term Evolution ◽  
Evolutionary Success ◽  
Lattice Proteins

It has long been debated whether natural selection acts primarily upon individual organisms, or whether it also commonly acts upon higher-level entities such as lineages. Two arguments against the effectiveness of long-term selection on lineages have been (i) that long-term evolutionary outcomes will not be sufficiently predictable to support a meaningful long-term fitness and (ii) that short-term selection on organisms will almost always overpower long-term selection. Here, we use a computational model of protein folding and binding called ‘lattice proteins’. We quantify the long-term evolutionary success of lineages with two metrics called the k -fitness and k -survivability. We show that long-term outcomes are surprisingly predictable in this model: only a small fraction of the possible outcomes are ever realized in multiple replicates. Furthermore, the long-term fitness of a lineage depends only partly on its short-term fitness; other factors are also important, including the ‘evolvability’ of a lineage—its capacity to produce adaptive variation. In a system with a distinct short-term and long-term fitness, evolution need not be ‘short-sighted’: lineages may be selected for their long-term properties, sometimes in opposition to short-term selection. Similar evolutionary basins of attraction have been observed in vivo , suggesting that natural biological lineages will also have a predictive long-term fitness.

Reliability and reproducibility of a clinical application of a simple technique for repeated circumferential leg measurements

2010 ◽  
Vol 26 (1) ◽  
pp. 14-19 ◽  
Author(s):  
A te Slaa ◽  
P Mulder ◽  
D Dolmans ◽  
P Castenmiller ◽  
G Ho ◽  
...  
Keyword(s):  
Simple Technique ◽  
Correlation Coefficients ◽  
Repeated Measurements ◽  
Medium Term ◽  
Short Term ◽  
Intra Class Correlation ◽  
Long Period ◽  
Simple Instrument ◽  
Reproducible Method

Objective The aim of this study is to determine the reliability and reproducibility of repeated tape measurements to assess the leg circumference during a long period. Methods A tape measure is a simple instrument that is applicable in the presence of oedema. Measurements were performed by four observers on 11 volunteers. Four measurements were done in the first week (short term), a fifth measurement at two weeks (medium term) and a sixth measurement was done at 12 weeks (long term). Results The short-, medium- and long-term intra-class correlation coefficients for repeated measurements were 0.90, 0.89 and 0.78, respectively. The short-term and long-term reproducibility indices equalled 4.4% and 6.5%. If only a single observer would be involved, the short-term intra-class correlation coefficients would improve to 0.94 (reproducibility index 3.3%). Conclusion Tape measurements have been proved to be a reliable and reproducible method to asses the lower limb circumference.

A Study on the Demonstration Experiment of the Solar Hot Water Heater for Dwellings

2005 ◽  
Vol 297-300 ◽  
pp. 2320-2326
Author(s):  
Dong Jo Yang ◽  
Jae Yeol Kim ◽  
Jae Ho Han
Keyword(s):  
Hot Water ◽  
Monitoring Systems ◽  
Short Term ◽  
Water Heater ◽  
Long Period ◽  
Water Heaters ◽  
Extensive Analysis ◽  
Demonstration Experiment ◽  
Routine Procedures

The main purpose of this investigation was to evaluate the performance of the solar hot water heater for dwellings in a long period of time. In order to evaluate the performance, there were 11 solar hot water heaters located in Gwangju Chosun University examined for their performance in 30 month period as a long term. The specific monitoring systems of each heater were constructed for the demonstrational research and the data base associated to each monitoring systems were assembled for an extensive analysis for variety of data obtained. The demonstrational experiments were conducted through following the routine procedures of 4 specific tests (the replicated drainage test, the daily drain test, the daily agitation test, the short-term test). The performance evaluation was based on the performances in insulating and solar collecting and the experimental routines and the performance experiments had incorporated the consumers’ use and need of the product. The ultimate goals of this investigation were to achieve consumers’ trust on the products and to promote the extensive distributions of the solar hot water heaters. The demonstrational research of this investigation was to evaluate the performance of the solar hot water heater for the residents for a long period of time. This research will be continued extensively.

scholarly journals Growth and business cycle in Argentina. A long-run approach, 1870–2015

2020 ◽  
Vol 28 (84) ◽  
pp. 197-220
Author(s):  
María Dolores Gadea ◽  
Isabel Sanz-Villarroya
Keyword(s):  
Long Term Evolution ◽  
Growth Potential ◽  
Short Term ◽  
Content Type ◽  
Developed Economies ◽  
Term Evolution ◽  
Long Run ◽  
High Volatility ◽  
The Moment

Purpose The purpose of this study is to focus deeply on the short term to explain the relative long-term evolution of the Argentinian economy in the long and the short term. Design/methodology/approach The study of the long-term evolution of the Argentine economy and identifying the moment in which it began to lose ground compared to other developed economies, such as Australia and Canada, constitutes the central axis of the historiography of this country. However, an additional problem presented by the Argentine economy is its high volatility. For this reason, the long term should be influenced by the short term, an issue that requires a more detailed study of the cyclical behavior and a deep analysis of the relationship between the long and the short term. Findings The results obtained point to a cyclical development that influences the long-term evolution and, therefore, explains Argentina’s convergence process with Australia and Canada. Frequent deep busts and short booms characterize the Argentine cycle, offsetting its long-term growth potential. Originality/value Although the long term has been profusely studied in Argentina, the short term has not been analyzed to the same extent, which is surprising given the extreme volatility of this economy (Prebisch, 1950). The studies performed on economic cycles have always been partial, disconnected from the long term and carried out without much technical rigor.

scholarly journals Variability in Protoplanetary Nebulae. VIII. A New Sample of Southern Hemisphere Objects

2021 ◽  
Vol 162 (6) ◽  
pp. 248
Author(s):  
Bruce J. Hrivnak ◽  
Gary Henson ◽  
Todd C. Hillwig ◽  
Wenxian Lu ◽  
Matthew T. Bremer ◽  
...  
Keyword(s):  
Southern Hemisphere ◽  
Light Curves ◽  
Spectral Energy ◽  
Energy Distributions ◽  
Term Study ◽  
Long Period ◽  
Protoplanetary Nebulae ◽  
Long Term Study ◽  
Light Variability

Abstract As part of our continuing study of light variability in protoplanetary nebulae (PPNe), we present the results from a long-term study of nine southern hemisphere objects. We have monitored their light variations over a nine-year interval from 2010 to 2018. These were supplemented by data from the ASAS-SN and ASAS-3 surveys, leading to combined light curves from 2000 to 2020. Pulsation periods were found in seven of the objects, although the three shortest must be regarded as tentative. The periods range from 24 to 73 days. When compared with the results of previous studies of the light variations in PPNe, we find that they show the same trends of shorter period and smaller light variations with higher temperatures. Luminosities were calculated based on the spectral energy distributions, reddening, and Gaia distances, and these confirm the identification of all but one as post-AGB objects. Three of the stars possess long-period variations of 5–19 yr. These are most likely due to the periodic obscuration of the star by a disk, suggesting the presence of a binary companion and a circumbinary disk.

Sign in / Sign up

Export Citation Format

Share Document