High-Frequency Periodic Patterns Driven by Non-Radiative Fields Coupled with Marangoni Convection Instabilities on Laser-Excited Surfaces

2019 ◽  
Author(s):  
Anton Rudenko ◽  
Anthony Abou-Saleh ◽  
Florent Pigeon ◽  
Cyril Mauclair ◽  
Florence Garrelie, Prof. ◽  
...  
Keyword(s):  
High Frequency ◽  
Marangoni Convection ◽  
Periodic Patterns

scholarly journals High-frequency periodic patterns driven by non-radiative fields coupled with Marangoni convection instabilities on laser-excited metal surfaces

2020 ◽  
Vol 194 ◽  
pp. 93-105 ◽  
Author(s):  
A. Rudenko ◽  
A. Abou-Saleh ◽  
F. Pigeon ◽  
C. Mauclair ◽  
F. Garrelie ◽  
...  
Keyword(s):  
High Frequency ◽  
Metal Surfaces ◽  
Marangoni Convection ◽  
Periodic Patterns

scholarly journals Reducing the Bias of the Smoothed Log Periodogram Regression for Financial High-Frequency Data

Econometrics ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 40
Author(s):  
Erhard Reschenhofer ◽  
Manveer K. Mangat
Keyword(s):  
Simulation Study ◽  
High Frequency ◽  
Mean Squared Error ◽  
Estimation Methods ◽  
High Frequency Data ◽  
Frequency Data ◽  
Periodic Patterns ◽  
Typical Sample ◽  
Squared Error ◽  
Proper Interpretation

For typical sample sizes occurring in economic and financial applications, the squared bias of estimators for the memory parameter is small relative to the variance. Smoothing is therefore a suitable way to improve the performance in terms of the mean squared error. However, in an analysis of financial high-frequency data, where the estimates are obtained separately for each day and then combined by averaging, the variance decreases with the sample size but the bias remains fixed. This paper proposes a method of smoothing that does not entail an increase in the bias. This method is based on the simultaneous examination of different partitions of the data. An extensive simulation study is carried out to compare it with conventional estimation methods. In this study, the new method outperforms its unsmoothed competitors with respect to the variance and its smoothed competitors with respect to the bias. Using the results of the simulation study for the proper interpretation of the empirical results obtained from a financial high-frequency dataset, we conclude that significant long-range dependencies are present only in the intraday volatility but not in the intraday returns. Finally, the robustness of these findings against daily and weekly periodic patterns is established.

Modeling High-Frequency Tire Tread Vibration as a Group of Traveling Bending Waves

2012 ◽  
Author(s):  
Masao Ishihama ◽  
Takayuki Kagaya
Keyword(s):  
High Frequency ◽  
Road Traffic ◽  
Traffic Noise ◽  
Propagation Speed ◽  
Road Surface ◽  
High Frequency Component ◽  
Road Traffic Noise ◽  
Periodic Patterns ◽  
Bending Vibration ◽  
Bending Waves

Tire noise is one of the major causes of road traffic noise. The high-frequency component dominates tire radiation noise, which is caused by tire tread bending vibration excited by rough road surface textures. As a result of such complicated phenomena, including very complicated tread vibration modes in the high-frequency range, heavy damping, and non-periodic patterns of the road surface texture, the modal analysis approach may appear to have a low potential for analyzing this problem. Based on the above considerations, we attempted to model the tread vibration phenomenon as a group of traveling bending waves excited at an array of pavement chippings. By setting the tread shoulders as reflecting lines, the interference effect of diagonally propagating direct and reflected waves is clarified. The vibration propagation speed and decay rate were estimated through shaker tests. The shape of the probability distribution function of the chippings intervals affects the traveling wave patterns. These observations will help engineers to develop less noisy tires.

scholarly journals Methodology of registration and reporting of electroencephalogram in unconsciousness patients

2019 ◽  
Vol 3 (29) ◽  
pp. 17-24
Author(s):  
M. V. Sinkin ◽  
E. A. Baranova ◽  
I. G. Komoltsev
Keyword(s):  
High Frequency ◽  
Unique Feature ◽  
Frequency Of Occurrence ◽  
Clinical Use ◽  
Rater Agreement ◽  
Impaired Consciousness ◽  
Periodic Patterns ◽  
Secondary Brain Damage ◽  
Recovery Of Consciousness ◽  
Recording Electrodes

A unique feature of electroencephalography (EEG) in patients with primary and secondary brain damage, accompanied by impaired consciousness, is the possibility of reducing the number of recording electrodes and the high frequency of occurrence of stereotypical combinations of graphoelements (special patterns). In EEG reporting in these patients, it is possible to use the special classification developed in 2013, which designates them as “rhythmic and periodic patterns” (RPP). Its implementation significantly increases the degree of inter-rater agreement, and clinical use allows not only to diagnose non-convulsive epileptic status accurately but to predict its occurrence at the preclinical stage and to assess the likelihood of recovery of consciousness in patients with coma. The review outlines the features of EEG recording in unconsciousness patients and describes the reporting methodology of rhythmic and periodic EEG patterns.

The Microstructure of Steatite (Protoenstatite)

1985 ◽  
Vol 43 ◽  
pp. 236-237
Author(s):  
W. E. Lee ◽  
A. H. Heuer
Keyword(s):  
High Frequency ◽  
Glass Ceramics ◽  
Magnesium Silicate ◽  
Beam Current ◽  
Glassy Matrix ◽  
Angle Of Incidence ◽  
X Ray ◽  
Mechanical And Electrical Properties ◽  
Argon Ions ◽  
High Temperature Polymorph

IntroductionTraditional steatite ceramics, made by firing (vitrifying) hydrous magnesium silicate, have long been used as insulators for high frequency applications due to their excellent mechanical and electrical properties. Early x-ray and optical analysis of steatites showed that they were composed largely of protoenstatite (MgSiO3) in a glassy matrix. Recent studies of enstatite-containing glass ceramics have revived interest in the polymorphism of enstatite. Three polymorphs exist, two with orthorhombic and one with monoclinic symmetry (ortho, proto and clino enstatite, respectively). Steatite ceramics are of particular interest a they contain the normally unstable high-temperature polymorph, protoenstatite.Experimental3mm diameter discs cut from steatite rods (∼10” long and 0.5” dia.) were ground, polished, dimpled, and ion-thinned to electron transparency using 6KV Argon ions at a beam current of 1 x 10-3 A and a 12° angle of incidence. The discs were coated with carbon prior to TEM examination to minimize charging effects.

Simulations of high-resolution images of amorphous silicon films

1986 ◽  
Vol 44 ◽  
pp. 544-545
Author(s):  
G. Y. Fan ◽  
J. M. Cowley
Keyword(s):  
Electron Microscope ◽  
High Frequency ◽  
Fourier Transformation ◽  
Amorphous Materials ◽  
Low Frequency ◽  
Chromatic Aberration ◽  
Structure Information ◽  
Frequency Components ◽  
High Resolution Images ◽  
Spatial Frequency Spectrum

It is well known that the structure information on the specimen is not always faithfully transferred through the electron microscope. Firstly, the spatial frequency spectrum is modulated by the transfer function (TF) at the focal plane. Secondly, the spectrum suffers high frequency cut-off by the aperture (or effectively damping terms such as chromatic aberration). While these do not have essential effect on imaging crystal periodicity as long as the low order Bragg spots are inside the aperture, although the contrast may be reversed, they may change the appearance of images of amorphous materials completely. Because the spectrum of amorphous materials is continuous, modulation of it emphasizes some components while weakening others. Especially the cut-off of high frequency components, which contribute to amorphous image just as strongly as low frequency components can have a fundamental effect. This can be illustrated through computer simulation. Imaging of a whitenoise object with an electron microscope without TF limitation gives Fig. 1a, which is obtained by Fourier transformation of a constant amplitude combined with random phases generated by computer.

SEM image sharpness analysis

1996 ◽  
Vol 54 ◽  
pp. 142-143
Author(s):  
M. T. Postek ◽  
A. E. Vladar
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Quantitative Information ◽  
Primary Electron ◽  
Image Sharpness ◽  
Critical Dimensions ◽  
Sem Image ◽  
Frequency Changes ◽  
Electron Microscopes ◽  
Scanning Electron

Fully automated or semi-automated scanning electron microscopes (SEM) are now commonly used in semiconductor production and other forms of manufacturing. The industry requires that an automated instrument must be routinely capable of 5 nm resolution (or better) at 1.0 kV accelerating voltage for the measurement of nominal 0.25-0.35 micrometer semiconductor critical dimensions. Testing and proving that the instrument is performing at this level on a day-by-day basis is an industry need and concern which has been the object of a study at NIST and the fundamentals and results are discussed in this paper.In scanning electron microscopy, two of the most important instrument parameters are the size and shape of the primary electron beam and any image taken in a scanning electron microscope is the result of the sample and electron probe interaction. The low frequency changes in the video signal, collected from the sample, contains information about the larger features and the high frequency changes carry information of finer details. The sharper the image, the larger the number of high frequency components making up that image. Fast Fourier Transform (FFT) analysis of an SEM image can be employed to provide qualitiative and ultimately quantitative information regarding the SEM image quality.

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