Low-frequency and high-frequency changes in temperature and effective humidity during the Holocene in south-central Sweden: implications for atmospheric and oceanic forcings of climate

2005 ◽  
Vol 25 (2-3) ◽  
pp. 285-297 ◽  
Author(s):  
H. Seppä ◽  
D. Hammarlund ◽  
K. Antonsson
Author(s):  
M. T. Postek ◽  
A. E. Vladar

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.


1991 ◽  
Vol 56 (2) ◽  
pp. 315-332 ◽  
Author(s):  
Janet D. Orcutt

Recent studies have shown a relation between low- and high-frequency environmental variability and aspects of culture. This paper uses low-frequency alluvial and hydrological changes on the Colorado Plateaus and high-frequency changes in moisture availability for the northern Rio Grande between A.D. 1150 and A.D. 1600 to derive expectations for changes in settlement organization on the Pajarito Plateau. The expectations are evaluated using data on the distribution of population and field houses in elevation zones. Changes in population size and aggregation also are reviewed. Low-frequency processes especially appear to have played a role in settlement change until A.D. 1450. After this date, settlement does not conform to expectations. Reasons for this are suggested, including a poor understanding of low- frequency processes, conflict, and human-induced environmental degradation.


We have been interested in three questions in relation to the problem which is under discussion to-day: the impedance changes, the pH changes and the protein changes during muscle contraction and relaxation. (a) Impedance changes With high-frequency current, we were not able to find any change in the conductivity of the muscle cell (Dubuisson 1935, 1936, 1937 a ). This confirms the earlier discoveries of MacClendon (1929) and Hartree (1933). At low frequency, changes were found due to modifications of some interfaces in the muscle cell. There is first of all a very fast decrease of impedance ( a wave) which occurs before the contraction and which is synchronous with the action potential (figure 8). Some years later, K. S. Cole (1938) found the same phenomenon in nerve.


2021 ◽  
Author(s):  
Reed W. Spencer ◽  
John A. Bomidi ◽  
Xu Huang

Abstract This paper reports the development of and the results of high frequency torsional oscillation (HFTO) tests performed on full-sized PDC drill bits and single cutters in a drilling laboratory. The research team used a pressurized laboratory drilling rig to test different drill bit designs in new and worn conditions. These tests were performed in different rock types, at different revolution per minute (RPM), weight on bit (WOB) and depth of cut (DOC) values. High frequency drill stem torque (5120 Hz) and in-bit tangential acceleration (1400 Hz) data were recorded, along with all other drilling parameters. Spectrograms of torque data were plotted to identify frequency changes in time. The torque data was filtered to remove the low frequency behavior and focus on the HFTO behavior. The high frequency torque signal correlates well with in-bit tangential accelerations. Root mean square (RMS) values of this filtered torque signal were calculated and plotted vs average WOB, depth of cut, and torque values. Sharp and worn bit geometry, were dull graded on a per cutter basis and were input to a 3D drilling modeling software and correlated with test data in order to determine the DOC at which wear flats or cutting faces engage the rock and cause changes in HFTO behavior. The main results from this research are 1) a lab test and data analysis were developed that can measure a drill bit's propensity to initiate HFTO vibrations in the BHA, 2) HFTO RMS high-pass filtered torque values generally increase with DOC, 3) bits in the new state show more HFTO behavior if cutter design is more aggressive, and 4) wear flat engagement causes high HFTO behavior.


Author(s):  
G. Y. Fan ◽  
J. M. Cowley

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.


1992 ◽  
Vol 1 (4) ◽  
pp. 52-55 ◽  
Author(s):  
Gail L. MacLean ◽  
Andrew Stuart ◽  
Robert Stenstrom

Differences in real ear sound pressure levels (SPLs) with three portable stereo system (PSS) earphones (supraaural [Sony Model MDR-44], semiaural [Sony Model MDR-A15L], and insert [Sony Model MDR-E225]) were investigated. Twelve adult men served as subjects. Frequency response, high frequency average (HFA) output, peak output, peak output frequency, and overall RMS output for each PSS earphone were obtained with a probe tube microphone system (Fonix 6500 Hearing Aid Test System). Results indicated a significant difference in mean RMS outputs with nonsignificant differences in mean HFA outputs, peak outputs, and peak output frequencies among PSS earphones. Differences in mean overall RMS outputs were attributed to differences in low-frequency effects that were observed among the frequency responses of the three PSS earphones. It is suggested that one cannot assume equivalent real ear SPLs, with equivalent inputs, among different styles of PSS earphones.


1971 ◽  
Vol 36 (4) ◽  
pp. 527-537 ◽  
Author(s):  
Norman P. Erber

Two types of special hearing aid have been developed recently to improve the reception of speech by profoundly deaf children. In a different way, each special system provides greater low-frequency acoustic stimulation to deaf ears than does a conventional hearing aid. One of the devices extends the low-frequency limit of amplification; the other shifts high-frequency energy to a lower frequency range. In general, previous evaluations of these special hearing aids have obtained inconsistent or inconclusive results. This paper reviews most of the published research on the use of special hearing aids by deaf children, summarizes several unpublished studies, and suggests a set of guidelines for future evaluations of special and conventional amplification systems.


2016 ◽  
Vol 17 (1) ◽  
pp. 66
Author(s):  
Maria Lina Silva Leite
Keyword(s):  

O objetivo deste estudo foi avaliar os efeitos do Método Pilates sobre a variabilidade da frequência cardíaca, na flexibilidade e nas variáveis antropométricas em indivíduos sedentários. O presente estudo contou com 14 voluntárias do sexo feminino, na faixa etária entre 40 e 55 anos, que realizaram 20 sessões de exercícios do Método Pilates, duas vezes por semana, com duração de 45 minutos cada sessão, dividida em três fases: repouso, exercício e recuperação. As variáveis estudadas foram: os dados antropométricos, flexibilidade avaliada utilizando o teste de sentar-e-alcançar com o Banco de Wells, e intervalos R-R usando um cardiotacômetro. O processamento dos sinais da frequência cardíaca foi efetuado em ambiente MatLab 6.1®, utilizando a TWC. Os dados coletados foram submetidos ao teste de normalidade de Shapiro Wilk e foi utilizado o teste de Wilcoxon e Anova One Way (α = 0,05). Nos resultados, observou-se que não houve diferenças significativas entre os valores antropométricos e de frequência cardíaca, porém houve aumento da flexibilidade com o treinamento. Comparando a primeira e a vigésima sessão com relação aos parâmetros low frequency (LF), high frequency (HF), e relação LF/HF, não houve diferença na fase de repouso e foram constatadas diferenças significativas de LF (p = 0,04) e HF (p = 0,04) na fase de exercício e diferença significativa de LF/HF (p = 0,05) na fase de recuperação. Comparando os parâmetros nos períodos de repouso, exercícios e recuperação durante a primeira sessão e durante a vigésima sessão, não houve diferença significativa nos parâmetros LF, HF e LF/HF. Pode-se concluir que, em relação à flexibilidade, foi observada uma melhora significativa, enquanto a análise da frequência cardíaca caracterizou a intensidade do exercício de 50% da capacidade funcional das voluntárias. Em relação aos parâmetros LF, HF e LF/HF foram observados um aumento da variabilidade da frequência cardíaca, provavelmente produto da atividade do Método Pilates. A Transformada Wavelet (TWC) mostrou-se um Método adequado para as análises da variabilidade da frequência cardíaca.Palavras-chave: frequência cardíaca, Transformada Wavelet, Pilates.


1998 ◽  
Vol 2 ◽  
pp. 115-122
Author(s):  
Donatas Švitra ◽  
Jolanta Janutėnienė

In the practice of processing of metals by cutting it is necessary to overcome the vibration of the cutting tool, the processed detail and units of the machine tool. These vibrations in many cases are an obstacle to increase the productivity and quality of treatment of details on metal-cutting machine tools. Vibration at cutting of metals is a very diverse phenomenon due to both it’s nature and the form of oscillatory motion. The most general classification of vibrations at cutting is a division them into forced vibration and autovibrations. The most difficult to remove and poorly investigated are the autovibrations, i.e. vibrations arising at the absence of external periodic forces. The autovibrations, stipulated by the process of cutting on metalcutting machine are of two types: the low-frequency autovibrations and high-frequency autovibrations. When the low-frequency autovibration there appear, the cutting process ought to be terminated and the cause of the vibrations eliminated. Otherwise, there is a danger of a break of both machine and tool. In the case of high-frequency vibration the machine operates apparently quiently, but the processed surface feature small-sized roughness. The frequency of autovibrations can reach 5000 Hz and more.


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