• Title/Summary/Keyword: Complex modulus

Search Result 235, Processing Time 0.023 seconds

Characteristic wave detection in ECG using complex-valued Continuous Wavelet Transforms

  • Berdakh, Abibullaev;Seo, Hee-Don
    • Journal of Biomedical Engineering Research
    • /
    • v.29 no.4
    • /
    • pp.278-285
    • /
    • 2008
  • In this study the complex-valued continuous wavelet transform (CWT) has been applied in detection of Electrocardiograms (ECG) as response to various signal classification methods such as Fourier transforms and other tools of time frequency analysis. Experiments have shown that CWT may serve as a detector of non-stationary signal changes as ECG. The tested signal is corrupted by short time events. We applied CWT to detect short-time event and the result image representation of the signal has showed us that one can easily find the discontinuity at the time scale representation. Analysis of ECG signal using complex-valued continuous wavelet transform is the first step to detect possible changes and alternans. In the second step, modulus and phase must be thoroughly examined. Thus, short time events in the ECG signal, and other important characteristic points such as frequency overlapping, wave onsets/offsets extrema and discontinuities even inflection points are found to be detectable. We have proved that the complex-valued CWT can be used as a powerful detector in ECG signal analysis.

A Study on the Ge Substituted LAS Ceramics Using Metla Alkoxide (금속알콕사이드를 이용한 LAS계 내열세라믹스의 제조시 Ge 성분의 치환에 관한 연구)

  • 장성중;김형태;이응상
    • Journal of the Korean Ceramic Society
    • /
    • v.32 no.11
    • /
    • pp.1233-1240
    • /
    • 1995
  • LAS system, which is difficult to be sintered, was densified by using the powder synthesized from metal alkoxides. Sinterability, thermal and mechanical properties were improved through synthesizing the complex oxide powder from the addition of Ge as an alkoxide. As a result, the synthesizing and sintering temperature of the LAS system lowered by about 10$0^{\circ}C$ and its modulus of rupture (MOR) increased twice higher compared to the sample from the oxide by the direct method.

  • PDF

Amino Silane, Vinyl Silane, TESPD, ZS(TESPD/Zinc Complex) Effects on Carbon Black/Clay Filled Chlorobutyl Rubber(CIIR) Compounds Part II: Effects on Soft Clay/Carbon Black Filled Compounds

  • Kim, Kwang-Jea
    • Carbon letters
    • /
    • v.10 no.2
    • /
    • pp.109-113
    • /
    • 2009
  • Various silanes, amino silane, vinyl silane, TESPD, and ZS (TESPD/zinc soap complex), are added into chlorinated isobutylene-isoprene copolymer (CIIR)/soft clay/carbon black (CB). The vulcanization characteristics, the processability, and the mechanical properties are measured. In soft clay/CB filled CIIR system, there are no significant changes in Mooney viscosity among compounds. Vinyl silane added compound shows a low extrusion torque. All the silane added compounds shows an increased modulus. The mechanical properties are significantly increased when the S2 is added into CIIR/soft clay/CB compounds.

Experimental Investigation Into the Dynamic Characteristics of Flexible Matrix Composite Driveshafts (유연복합재 구동축의 동특성에 관한 실험 분석)

  • Shin Eung-Soo
    • Transactions of the Korean Society of Machine Tool Engineers
    • /
    • v.15 no.2
    • /
    • pp.93-98
    • /
    • 2006
  • This study provides a comprehensive experimental study on the dynamic characteristics of a flexible matrix composite(FMC) driveshaft. A primary objective is to verify the analytic results of the FMC drivetrain based on the equivalent complex modulus approach and the classical lamination theory. A test rig has been constructed, which consists of a FMC shaft, a foundation beam, bearings, external dampers and a driving motor. The frequency response functions and transient responses are obtained from the external excitation and the spin-up testings. It turns out that the analytic results are in good agreement with the experimental ones.

Visocoelasticity of Electrorhedlogical Fluid from Vertical Oscillation Rheometer (수직진동 rheometer를 이용한 전도유체의 점탄성 연구)

  • Kim, Sang-Guk;Kim, Dong-Chan;Choe, Yeong-Jin;Jo, Min-Seong
    • Korean Journal of Materials Research
    • /
    • v.6 no.11
    • /
    • pp.1067-1073
    • /
    • 1996
  • 본 연구에서는 직접 제작된 전도유체(electrorheological fluid)용 수직진동 rhemeter 기기상의 구조 해석 및 실험을 실시하였다. 수직진동 rheomether는 간단하게 제작이 가능하고, 고전압 발생장치를 연결하므로 전동유체의 점탄성 특성을 비교적 쉽게 측정할 수 있다. Rheometer의 구조적 변수와 측정된 힘, 변형 등을 이용하여 복소 점도(complex viscosity), 복소 전단 변형률(complex shear modulus), loss tangent 등의 선형 점탄성 물질 함수를 직접 계산할 수 있으며, corn starch를 polybutene/kerosene에 분산시킨 전동유체를 이용하여 전기장하의 점탄성을 측정하였다.

  • PDF

Experimental Investigation into the Dynamic Characteristics of Flexible Matrix Composite Driveshafts (유연복합재 구동축의 동특성에 관한 실험 분석)

  • Shin, Eung-Soo;Lim, Byung-Soo
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2005.11a
    • /
    • pp.123-126
    • /
    • 2005
  • This study provides a comprehensive experimental study on the dynamic characteristics of a flexible matrix composite(FMC) driveshaft. A primary objective is to verify the analytic results of the FMC drivetrain based on the equivalent complex modulus approach and the classical lamination theory. A testrig has been constructed, which consists of a FMC shaft, a foundation beam, bearings, external dampers and a driving motor. The frequency response functions and transient responses are obtained from the external excitation and the spinup testings. It turns out that the analytic results are in good agreement with the experimental ones.

  • PDF

Nonlinear free vibration analysis of moderately thick viscoelastic plates with various geometrical properties

  • Nasrin Jafari;Mojtaba Azhari
    • Steel and Composite Structures
    • /
    • v.48 no.3
    • /
    • pp.293-303
    • /
    • 2023
  • In this paper, geometrically nonlinear free vibration analysis of Mindlin viscoelastic plates with various geometrical and material properties is studied based on the Von-Karman assumptions. A novel solution is proposed in which the nonlinear frequencies of time-dependent plates are predicted according to the nonlinear frequencies of plates not dependent on time. This method greatly reduces the cost of calculations. The viscoelastic properties obey the Boltzmann integral law with constant bulk modulus. The SHPC meshfree method is employed for spatial discretization. The Laplace transformation is used to convert equations from the time domain to the Laplace domain and vice versa. Solving the nonlinear complex eigenvalue problem in the Laplace-Carson domain numerically, the nonlinear frequencies, the nonlinear viscous damping frequencies, and the nonlinear damping ratios are verified and calculated for rectangular, skew, trapezoidal and circular plates with different boundary conditions and different material properties.

INEQUALITIES FOR COMPLEX POLYNOMIAL WITH RESTRICTED ZEROS

  • Istayan Das;Robinson Soraisam;Mayanglambam Singhajit Singh;Nirmal Kumar Singha;Barchand Chanam
    • Nonlinear Functional Analysis and Applications
    • /
    • v.28 no.4
    • /
    • pp.943-956
    • /
    • 2023
  • Let p(z) be a polynomial of degree n and for any complex number 𝛽, let D𝛽p(z) = np(z) + (𝛽 - z)p'(z) denote the polar derivative of the polynomial with respect to 𝛽. In this paper, we consider the class of polynomial $$p(z)=(z-z_0)^s \left(a_0+\sum\limits_{{\nu}=0}^{n-s}a_{\nu}z^{\nu}\right)$$ of degree n having a zero of order s at z0, |z0| < 1 and the remaining n - s zeros are outside |z| < k, k ≥ 1 and establish upper bound estimates for the maximum of |D𝛽p(z)| as well as |p(Rz) - p(rz)|, R ≥ r ≥ 1 on the unit disk.

Preparation and Stabilization of an O/W Emulsion Using Liquid Crystalline Phases (액정상을 이용한 O/W형 에멀젼의 제조 및 제형 안정화에 관한 연구)

  • An, Bong-Jeun;Lee, Jin-Tae;Lee, In-Chol;Kwak, Jae-Hoon;Park, Jung-Mi;Park, Chan-Ik
    • Journal of the Korean Applied Science and Technology
    • /
    • v.21 no.1
    • /
    • pp.31-36
    • /
    • 2004
  • Liquid crystalline phases were formed from acylglutamate; polyglyceryl-10 myristate and glycerine mixture and they were used as a base material for preparing an O/W emulsion. When an oil phase is added into the liquid crystalline phases, it was inserted into the dispersed liquid crystal droplets rather than stayed outside the liquid crystals, which can be known by the fact that the size of liquid crystal droplets increases with the increasing oil phase content. Along with the increase in the droplet size, the complex modulus increases from 100 to 350 pascals and the loss angle decreases from 60 to 24 degrees, from which it can be known that the increase in the internal phase volume results in the increase in the elastic property of oil in liquid crystalline-phases (O/LC). When the water phase was lastly added into the O/LC phase, the emulsification occurred to form a O/W emulsion and the averaged particle size of the O/W emulsion changes from 22.5nm to 538nm with the addition of water phase. The results from the droplet size measurements and stability tests under accelerated conditions such as high temperature show that the obtained O/W emulsion is very consistent with time.