scholarly journals A Study on an Empirical Formula for Amplification Factor Based on Fundamental Peak Frequency and Amplitude of Microtremor H/V

2019 ◽  
Vol 19 (7) ◽  
pp. 7_41-7_55
Author(s):  
Hayato NISHIKAWA ◽  
Tatsuya NOGUCHI ◽  
Masakatsu MIYAJIMA ◽  
Takao KAGAWA
Keyword(s):  
Empirical Formula ◽  
Amplification Factor ◽  
Peak Frequency

Approximate Analytical Expressions of the Fundamental Peak Frequency and the Amplification Factor of S-wave Transfer Function in a Viscoelastic Layered Model

2018 ◽  
Vol 176 (4) ◽  
pp. 1433-1443
Author(s):  
Tran Thanh Tuan ◽  
Pham Chi Vinh ◽  
Abdelkrim Aoudia ◽  
Truong Thi Thuy Dung ◽  
Daniel Manu-Marfo
Keyword(s):  
Transfer Function ◽  
Amplification Factor ◽  
Peak Frequency ◽  
S Wave ◽  
Layered Model ◽  
Analytical Expressions

The growth of duration-limited wind waves

1978 ◽  
Vol 85 (4) ◽  
pp. 705-730 ◽  
Author(s):  
Hisashi Mitsuyasu ◽  
Kunio Rikiishi
Keyword(s):  
Growth Rate ◽  
Exponential Growth ◽  
Empirical Formula ◽  
Wind Wave ◽  
Wind Waves ◽  
Wave Spectrum ◽  
Peak Frequency ◽  
Spectral Peak ◽  
Spectral Energy ◽  
Wave Spectra

Laboratory measurements have been made of the one-dimensional spectra of the duration-limited wind waves which are generated when a wind abruptly begins to blow over a water surface, maintaining a constant speed during the succeeding period of time. The duration dependences of the wave energy E and the spectral peak frequency fm determined from the measured spectra are slightly different from those inferred from the fetch dependences of these quantities. The normalized spectra of the duration-limited wind waves are also slightly different from those of fetch-limited wind waves: the concentration of the normalized spectral energy near the spectral peak frequency is smaller, in many cases, for the duration-limited wind waves than for fetch-limited wind waves. The exponential growth rates β of the duration-limited wind-wave spectra are generally larger than those of fetch-limited wind-wave spectra. Furthermore, both for the duration-limited wind waves and for fetch-limited wind waves the exponential growth rate has a behaviour which is different from the empirical formula of Snyder & Cox (1966). A new empirical formula for the growth rate of the wave spectrum is proposed, from which the empirical formula of Snyder & Cox (1966) can be derived as a special case. Agreement between the new empirical formula and the experimental results is satisfactory for fetch-limited wave spectra, but is confined to the qualitative features for the duration-limited wave spectra.

Influence of free convection on the diffusion current to a sphere in a laminar forced flow regime

1985 ◽  
Vol 50 (12) ◽  
pp. 2697-2714
Author(s):  
Arnošt Kimla ◽  
Jiří Míčka
Keyword(s):  
Asymptotic Expansion ◽  
Free Convection ◽  
Boundary Value Problem ◽  
Concentration Gradient ◽  
Empirical Formula ◽  
Convective Diffusion ◽  
Forced Flow ◽  
Diffusion Current ◽  
Wide Range ◽  
Free And Forced Convection

The formulation and solution of a boundary value problem is presented, describing the influence of the free convective diffusion on the forced one to a sphere for a wide range of Rayleigh, Ra, and Peclet, Pe, numbers. It is assumed that both the free and forced convection are oriented in the same sense. Numerical results obtained by the method of finite differences were approximated by an empirical formula based on an analytically derived asymptotic expansion for Pe → ∞. The concentration gradient at the surface and the total diffusion current calculated from the empirical formula agree with those obtained from the numerical solution within the limits of the estimated errors.

scholarly journals A MEMS µ-Preconcentrator Employing a Carbon Molecular Sieve Membrane for Highly Volatile Organic Compound Sampling

Chemosensors ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 104
Author(s):  
Hung-Yang Kuo ◽  
Wei-Riu Cheng ◽  
Tzu-Heng Wu ◽  
Horn-Jiunn Sheen ◽  
Chih-Chia Wang ◽  
...  
Keyword(s):  
Organic Compound ◽  
Organic Compounds ◽  
Volatile Organic Compound ◽  
Molecular Sieve ◽  
Amplification Factor ◽  
Microfluidic Channel ◽  
Carbon Molecular Sieve ◽  
Volatile Organic ◽  
Chromatographic Peaks ◽  
Gaseous Toluene

This paper presents the synthesis and evaluation of a carbon molecular sieve membrane (CMSM) grown inside a MEMS-fabricated μ-preconcentrator for sampling highly volatile organic compounds. An array of µ-pillars measuring 100 µm in diameter and 250 µm in height were fabricated inside a microfluidic channel to increase the attaching surface for the CMSM. The surface area of the CMSM was measured as high as 899 m2/g. A GC peak amplification factor >2 × 104 was demonstrated with gaseous ethyl acetate. Up to 1.4 L of gaseous ethanol at the 100 ppb level could be concentrated without exceeding the capacity of this microchip device. Sharp desorption chromatographic peaks (<3.5 s) were obtained while using this device directly as a GC injector. Less volatile compounds such as gaseous toluene, m-xylene, and mesitylene appeared to be adsorbed strongly on CMSM, showing a memory effect. Sampling parameters such as sample volatilities, sampling capacities, and compound residual issues were empirically determined and discussed.

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