Experimental Determination of Corneal Elastic Constants and Their Use in Biomechanical Modeling

Corneal biomechanics aims to establish the physico-mathematical bases that allow for predicting the corneal response to physiological and pathological situations by creating models of tissue behavior. Determining the characteristic parameters of these models is a formidable challenge in the biomechanical modeling process. To contribute to corneal tissue characterization, an experimental set-up was designed, built and tested to study corneal behavior by applying changes in pressure. The elastic constants of porcine corneas were determined, and a Young’s modulus of 0.188 MPa and 26.22% hysteresis were obtained. A computational cornea model was developed to analyze the influence of different factors. Minor variations in the applied conditions were found for apical displacement and pachymetry, and the corneal behavior was reproduced. However, the optical power behavior was affected by variations in the applied conditions, and the experimentally obtained data could not be reproduced. Despite its importance, this parameter has not been analyzed in-depth by other studies, which shows that the quality of a biomechanical cornea model should not be evaluated only by apical displacement.

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A determination of the elastic constants of beta quartz

10.31274/rtd-180813-14218 ◽

1942 ◽

Author(s):

Erwin William Kammer

Keyword(s):

Elastic Constants

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Determination of Diffraction Elastic Constants of Gamma-Double-Prime in Polycrystalline Ni-Base Superalloys

SSRN Electronic Journal ◽

10.2139/ssrn.3458152 ◽

2019 ◽

Author(s):

R.Y. Zhang ◽

H.L. Qin ◽

Z.N. Bi ◽

J. Li ◽

S. Paul ◽

...

Keyword(s):

Elastic Constants

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Respirometry for determination of the influents SS-concentration

Water Science & Technology ◽

10.2166/wst.1996.0031 ◽

1996 ◽

Vol 33 (1) ◽

pp. 311-323 ◽

Cited By ~ 2

Author(s):

A. Witteborg ◽

A. van der Last ◽

R. Hamming ◽

I. Hemmers

Keyword(s):

Experimental Design ◽

Activated Sludge ◽

Substrate Concentration ◽

Full Scale ◽

Activated Sludge Process ◽

Respiration Rates ◽

On Line ◽

Large Measurement ◽

Set Up

A method is presented for determining influent readily biodegradable substrate concentration (SS). The method is based on three different respiration rates, which can be measured with a continuous respiration meter which is operated in a cyclic way. Within the respiration meter nitrification is inhibited through the addition of ATU. Simulations were used to develop the respirometry set-up and decide upon the experimental design. The method was tested as part of a large measurement programme executed at a full-scale plant. The proposed respirometry set-up has been shown to be suitable for a semi-on-line determination of an influent SS which is fully based on the IAWQ #1 vision of the activated sludge process. The YH and the KS play a major role in the principle, and should be measured directly from the process.

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Determination of trace concentrations of copper by FIA-FAAS after preconcentration on chelating sorbents

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19891785 ◽

1989 ◽

Vol 54 (7) ◽

pp. 1785-1794 ◽

Cited By ~ 7

Author(s):

Vlastimil Kubáň ◽

Josef Komárek ◽

Zbyněk Zdráhal

Keyword(s):

Sampling Frequency ◽

Copper Determination ◽

Flow Rates ◽

Sample Injection ◽

Injection Flow ◽

Chelating Sorbents ◽

Set Up ◽

Trace Concentrations ◽

Better Than

A FIA-FAAS apparatus containing a six-channel sorption equipment with five 3 x 26 mm microcolumns packed with Spheron Oxin 1 000, Ostsorb Oxin and Ostsorb DTTA was set up. Combined with sorption from 0.002M acetate buffer at pH 4.2 and desorption with 2M-HCl, copper can be determined at concentrations up to 100, 150 and 200 μg l-1, respectively. For sample and eluent flow rates of 5.0 and 4.0 ml min-1, respectively, and a sample injection time of 5 min, the limit of copper determination is LQ = 0.3 μg l-1, repeatability sr is better than 2% and recovery is R = 100 ± 2%. The enrichment factor is on the order of 102 and is a linear function of time (volume) of sample injection up to 5 min and of the sample injection flow rate up to 11 ml min-1 for Spheron Oxin 1 000 and Ostsorb DTTA. For times of sorption of 60 and 300 s, the sampling frequency is 70 and 35 samples/h, respectively. The parameters of the FIA-FAAS determination (acetylene-air flame) are comparable to or better than those achieved by ETA AAS. The method was applied to the determination of traces of copper in high-purity water.

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Extra-Column Effects in Determination of Rate Parameters by the Chromatographic Method

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19960844 ◽

1996 ◽

Vol 61 (6) ◽

pp. 844-855 ◽

Cited By ~ 7

Author(s):

Olga Šolcová ◽

Petr Schneider

Keyword(s):

Chromatographic Method ◽

Dynamic Method ◽

Axial Dispersion ◽

Transport Parameters ◽

Porous Particles ◽

Loop Detector ◽

Single Pellet ◽

Set Up ◽

Extra Column Effects

It was shown that the sampling loop, detector and connecting elements in the chromatographic set-up for determination of transport parameters by the dynamic method significantly influence the response peaks from columns packed with porous or nonporous particles. A method, based on the use of convolution theorem, was developed which can take these effects into account. The applicability of this method was demonstrated on the case of axial dispersion in a single-pellet-string column (SPSR) packed with nonporous particles. It is possible to handle also responses from columns packed with porous particles by a similar procedure.

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Influence of a Thermal Pad on Selected Parameters of Power LEDs

Energies ◽

10.3390/en13143732 ◽

2020 ◽

Vol 13 (14) ◽

pp. 3732

Author(s):

Krzysztof Górecki ◽

Przemysław Ptak ◽

Tomasz Torzewicz ◽

Marcin Janicki

Keyword(s):

Optical Properties ◽

Thermal Resistance ◽

Optical Power ◽

Junction Temperature ◽

Operating Parameters ◽

Cold Plate ◽

Optical Efficiency ◽

Forward Current ◽

Measurement Results ◽

Set Up

This paper is devoted to the analysis of the influence of thermal pads on electric, optical, and thermal parameters of power LEDs. Measurements of parameters, such as thermal resistance, optical efficiency, and optical power, were performed for selected types of power LEDs operating with a thermal pad and without it at different values of the diode forward current and temperature of the cold plate. First, the measurement set-up used in the paper is described in detail. Then, the measurement results obtained for both considered manners of power LED assembly are compared. Some characteristics that illustrate the influence of forward current and temperature of the cold plate on electric, thermal, and optical properties of the tested devices are presented and discussed. It is shown that the use of the thermal pad makes it possible to achieve more advantageous values of operating parameters of the considered semiconductor devices at lower values of their junction temperature, which guarantees an increase in their lifetime.

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