A Pulsed Diaphragm Piezoelectric Pump Using Centrifugal Force

2014 ◽  
Vol 915-916 ◽  
pp. 309-312
Author(s):  
Zhi Sen Deng ◽  
Yu Ting Ma
Keyword(s):  
Resonant Frequency ◽  
Centrifugal Force ◽  
High Frequency ◽  
Driving Force ◽  
Piezoelectric Materials ◽  
Tap Water ◽  
Low Frequency ◽  
Frequency Characteristics ◽  
Piezoelectric Pump ◽  
Input And Output

A pulsed diaphragm piezoelectric pump using centrifugal force is introduced in this paper. It utilizes centrifugal force in the swing motion of a vibrating tube as the driving force, and to input and output liquid continuously at first bending resonant frequency. The piezoelectric pump based on this principle is expected to effectively coordinate the high frequency characteristics of piezoelectric materials and low frequency characteristics of check valves. Resonant frequency of the pump is studied. A prototype pump was fabricated and tested. Experimental results show that the pump can hold and discharge very precise volume of liquid in every pulse, and can pump tap water at a flow rate of 6.12ml/min under a backpressure of 0.3kPa.

Transfer of Learning in Transformed Random-Dot Stereostimuli

Perception ◽  
1982 ◽  
Vol 11 (4) ◽  
pp. 409-414 ◽  
Author(s):  
Nigel R Long
Keyword(s):  
Spatial Frequency ◽  
High Frequency ◽  
Transfer Of Learning ◽  
Low Frequency ◽  
Frequency Characteristics ◽  
Frequency Transformations

The transfer of learning between normal and monocularly-transformed small-disparity, random-dot stereostimuli has been examined under extended viewing conditions. When the disparity value was constant, transfer of learning between normal and monocularly-transformed stereostimuli was disrupted by both low-frequency and high-frequency transformations. These results suggest that stereolearning is restricted to disparity units that are selective to the same spatial-frequency characteristics.

Tuned Damping of an Air-Mounted Isolation System

2004 ◽  
Author(s):  
Reza Kashani ◽  
Kazim Mirza
Keyword(s):  
Resonant Frequency ◽  
High Frequency ◽  
Low Frequency ◽  
Helmholtz Resonator ◽  
Isolation System ◽  
And Mathematics ◽  
High Level ◽  
Three Degree Of Freedom ◽  
Tuned Damper ◽  
Isolation Performance

Air mounts can provide the highest degree of isolation of any type vibration isolator. Soft-mounting, and thus high level of low-frequency isolation, with system natural frequency as low as 1 Hz can be achieved. Due to their construction, air mounts have negligible damping. Although, this almost undamped nature of air mounts enhances the high-frequency isolation, provisions should be made to address the lack of isolation resulting in excessive body displacements around the resonant frequencies, especially when the system is exposed to shock inputs. While the addition of viscous damping to the air mount is proposed in the literature but it is not recommended in most applications. This is because it deteriorates the mount’s high-frequency isolation performance. Instead, it would be highly desirable to add tuned damping to the mounted system at its resonant frequency (ies). The challenge in doing so, is realizing a damper tunable to a very low frequency and yet not be prohibitively large. A novel tuned damping mechanism is proposed in this paper. It adds damping to an air mount only at the resonant frequency (ies), via a bi-fluid Helmholtz resonator. In an illustrative example the mechanics and mathematics (modeling) of a one and three degree of freedom air mounted systems equipped with a tuned damper, as well as the tuning of such damper are discussed. The example also demonstrates the effectiveness of the air mount with the tuned damper.

Towards a constructional account of high and low frequency binominal quantifiers in Spanish

2012 ◽  
Vol 23 (2) ◽  
pp. 421-478 ◽  
Author(s):  
Katrien Verveckken,
Keyword(s):  
High Frequency ◽  
Driving Force ◽  
Language Change ◽  
Low Frequency ◽  
Corpus Analysis ◽  
Analogical Thinking ◽  
Semantic Clustering ◽  
The Individual ◽  
Present Case Study

AbstractThis paper aims to provide a clearer understanding of the widely discussed topic of grammaticalization of constructions. One unresolved problem concerns the identification of the relevant constructional level of language change, i.e., either the substantial level of specific occurrences or the schematic level of generalizations. Another issue addressed in many current analyses is the degree of schematicity of analogical forces.The present case study addresses these questions in the context of Spanish binominal quantifiers, basing its claims on synchronic and diachronic corpus analysis. The synchronic layering of uses in Present-Day Spanish—which encompasses quantifying and premodifying uses in addition to literal head uses—will be argued to reflect the outcome of grammaticalization. The synchronic as well as diachronic semantic clustering of binominal quantifiers and the prototype function of high-frequency montón de ‘heap of’ are hypothesized to result from the close interaction between analogical thinking and conceptual persistence. In line with the usage-based approach to language change, the dramatic increase in frequency observed for quantifying montón de will lead me to distinguish several constructional levels of change and to establish a schematic ‘N1 de N2’ pattern linked to quantity as a driving force. The strong collocational preferences characterizing the individual binominal constructions, the systematicity of the premodifying use and the tendency to reinforce conceptual elements of the original head use will be accounted for by considering the quantity assessment of the (schematic) binominal string as just one possible realization of co-extensiveness, in addition to quality assessment.

Finite Element Analysis of Piezoelectric Materials

2013 ◽  
Vol 860-863 ◽  
pp. 872-875
Author(s):  
Ai Guo Zhang ◽  
Tie Jun Yang ◽  
Jing Tao Du ◽  
Peng Lv ◽  
Xin Guang Li
Keyword(s):  
Finite Element ◽  
High Frequency ◽  
Piezoelectric Materials ◽  
Low Frequency ◽  
Signal Frequency ◽  
Affecting Factors ◽  
Element Analysis ◽  
Modeling And Analysis ◽  
Voltage Signal ◽  
Simulation Results

The ANSYS finite element techniques were used for modeling and analysis of piezoelectric materials. The single piezoelectric sheet model was presented. The basic characteristic of the piezoelectric materials were analyzed and the affecting factors of characteristics were derived. The high frequency simulation results showed that the displacement responses of piezoelectric materials were very large delay in boost and buck under the high frequency voltage signal, and that was adverse to the vibration control. The low frequency voltage simulation results showed that the displacement response frequency and voltage signal frequency were exactly the same. The model thickness greatly affected its stiffness and indirectly affected its output characteristics.

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.

Real Ear Sound Pressure Levels Developed by Three Portable Stereo System Earphones

1992 ◽  
Vol 1 (4) ◽  
pp. 52-55 ◽  
Author(s):  
Gail L. MacLean ◽  
Andrew Stuart ◽  
Robert Stenstrom
Keyword(s):  
High Frequency ◽  
Sound Pressure ◽  
Low Frequency ◽  
Test System ◽  
Output Frequency ◽  
Frequency Effects ◽  
Adult Men ◽  
Frequency Responses ◽  
Significant Difference ◽  
Sound Pressure Levels

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.

Evaluation of Special Hearing Aids for Deaf Children

1971 ◽  
Vol 36 (4) ◽  
pp. 527-537 ◽  
Author(s):  
Norman P. Erber
Keyword(s):  
Hearing Aids ◽  
High Frequency ◽  
Hearing Aid ◽  
Low Frequency ◽  
Acoustic Stimulation ◽  
Deaf Children ◽  
Frequency Range ◽  
Frequency Limit ◽  
Unpublished Studies ◽  
Published Research

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.

Efeitos do Método Pilates sobre a variabilidade da frequência cardíaca, flexibilidade e variáveis antropométricas em indivíduos sedentários

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

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.

Dynamics of the processes in metal machining

1998 ◽  
Vol 2 ◽  
pp. 115-122
Author(s):  
Donatas Švitra ◽  
Jolanta Janutėnienė
Keyword(s):  
High Frequency ◽  
Machine Tools ◽  
Metal Cutting ◽  
Cutting Tool ◽  
Low Frequency ◽  
Metal Cutting Machine ◽  
Cutting Machine ◽  
Metal Machining

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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