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Haruki Kawamura - One of the best experts on this subject based on the ideXlab platform.
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Pressure calibration of diamond anvil raman gauge to 410 gpa
Journal of Physics: Conference Series, 2010Co-Authors: Yuichi Akahama, Haruki KawamuraAbstract:The first-order Raman band of diamond anvils has been investigated at Pressure up to 410 GPa in order to develop an optical Pressure Determination method. The high-frequency edge of the band was calibrated by the Pressure scale of the equation of state of Pt. A unique relationship between the edge-frequency and the sample Pressure was confirmed up to the highest Pressure, while the edge frequency reaches to 1907 cm−1 at 410 GPa. Usefulness of the diamond anvil Raman gauge as a laboratory-based Pressure Determination method in the multimegabar Pressure range has been discussed.
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Pressure calibration of diamond anvil raman gauge to 310gpa
Journal of Applied Physics, 2006Co-Authors: Yuichi Akahama, Haruki KawamuraAbstract:In order to develop an optical method for Pressure Determination in the multimegabar region, the first-order Raman spectra of diamond anvils were investigated at Pressures up to 310GPa. The high-frequency edge of the Raman band, which corresponds to the Raman shift of the anvil culet due to the normal stress, was calibrated against the sample Pressure derived from the equation of state of Pt. The obtained Pressure dependence of the edge frequency demonstrates the reliability of this diamond anvil Raman gauge. Up to the maximum Pressure of this study, the relation between Raman frequency and normal stress at the diamond anvil culet is formally similar to the equation of state of a hydrostatically compressed isotropic elastic body having a bulk modulus of K0=547(11)GPa and a Pressure derivative of the bulk modulus K0′=3.75(20).
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Pressure calibration of diamond anvil raman gauge to 310 gpa
Journal of Applied Physics, 2006Co-Authors: Yuichi Akahama, Haruki KawamuraAbstract:In order to develop an optical method for Pressure Determination in the multimegabar region, the first-order Raman spectra of diamond anvils were investigated at Pressures up to 310GPa. The high-frequency edge of the Raman band, which corresponds to the Raman shift of the anvil culet due to the normal stress, was calibrated against the sample Pressure derived from the equation of state of Pt. The obtained Pressure dependence of the edge frequency demonstrates the reliability of this diamond anvil Raman gauge. Up to the maximum Pressure of this study, the relation between Raman frequency and normal stress at the diamond anvil culet is formally similar to the equation of state of a hydrostatically compressed isotropic elastic body having a bulk modulus of K0=547(11)GPa and a Pressure derivative of the bulk modulus K0′=3.75(20).
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high Pressure raman spectroscopy of diamond anvils to 250gpa method for Pressure Determination in the multimegabar Pressure range
Journal of Applied Physics, 2004Co-Authors: Yuichi Akahama, Haruki KawamuraAbstract:The first-order Raman spectra of diamond anvils used in a gasketed high-Pressure cell have been measured at Pressure up to 250GPa. The high-frequency edge of the Raman band, which corresponds to the Raman shift of the culet face, is represented by a function of Pressure in the sample chamber up to 250GPa. The dependence is almost independent on loading conditions. The application of the Pressure dependence for Pressure Determination up to the multimegabars Pressure region is proposed.
Yuichi Akahama - One of the best experts on this subject based on the ideXlab platform.
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Pressure calibration of diamond anvil raman gauge to 410 gpa
Journal of Physics: Conference Series, 2010Co-Authors: Yuichi Akahama, Haruki KawamuraAbstract:The first-order Raman band of diamond anvils has been investigated at Pressure up to 410 GPa in order to develop an optical Pressure Determination method. The high-frequency edge of the band was calibrated by the Pressure scale of the equation of state of Pt. A unique relationship between the edge-frequency and the sample Pressure was confirmed up to the highest Pressure, while the edge frequency reaches to 1907 cm−1 at 410 GPa. Usefulness of the diamond anvil Raman gauge as a laboratory-based Pressure Determination method in the multimegabar Pressure range has been discussed.
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Pressure calibration of diamond anvil raman gauge to 310gpa
Journal of Applied Physics, 2006Co-Authors: Yuichi Akahama, Haruki KawamuraAbstract:In order to develop an optical method for Pressure Determination in the multimegabar region, the first-order Raman spectra of diamond anvils were investigated at Pressures up to 310GPa. The high-frequency edge of the Raman band, which corresponds to the Raman shift of the anvil culet due to the normal stress, was calibrated against the sample Pressure derived from the equation of state of Pt. The obtained Pressure dependence of the edge frequency demonstrates the reliability of this diamond anvil Raman gauge. Up to the maximum Pressure of this study, the relation between Raman frequency and normal stress at the diamond anvil culet is formally similar to the equation of state of a hydrostatically compressed isotropic elastic body having a bulk modulus of K0=547(11)GPa and a Pressure derivative of the bulk modulus K0′=3.75(20).
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Pressure calibration of diamond anvil raman gauge to 310 gpa
Journal of Applied Physics, 2006Co-Authors: Yuichi Akahama, Haruki KawamuraAbstract:In order to develop an optical method for Pressure Determination in the multimegabar region, the first-order Raman spectra of diamond anvils were investigated at Pressures up to 310GPa. The high-frequency edge of the Raman band, which corresponds to the Raman shift of the anvil culet due to the normal stress, was calibrated against the sample Pressure derived from the equation of state of Pt. The obtained Pressure dependence of the edge frequency demonstrates the reliability of this diamond anvil Raman gauge. Up to the maximum Pressure of this study, the relation between Raman frequency and normal stress at the diamond anvil culet is formally similar to the equation of state of a hydrostatically compressed isotropic elastic body having a bulk modulus of K0=547(11)GPa and a Pressure derivative of the bulk modulus K0′=3.75(20).
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high Pressure raman spectroscopy of diamond anvils to 250gpa method for Pressure Determination in the multimegabar Pressure range
Journal of Applied Physics, 2004Co-Authors: Yuichi Akahama, Haruki KawamuraAbstract:The first-order Raman spectra of diamond anvils used in a gasketed high-Pressure cell have been measured at Pressure up to 250GPa. The high-frequency edge of the Raman band, which corresponds to the Raman shift of the culet face, is represented by a function of Pressure in the sample chamber up to 250GPa. The dependence is almost independent on loading conditions. The application of the Pressure dependence for Pressure Determination up to the multimegabars Pressure region is proposed.
Jean Talandier - One of the best experts on this subject based on the ideXlab platform.
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Assessment of Swelling Pressure Determination Methods with Intact Callovo-Oxfordian Claystone
Rock Mechanics and Rock Engineering, 2020Co-Authors: Feng Zhang, Nathalie Conil, Yu-jun Cui, Jean TalandierAbstract:There are several methods for the Determination of soil swelling Pressure. In this study, such common methods were assessed using intact Callovo-Oxfordian (COx) claystone samples extracted in the direction perpendicular to the bedding plane, in the French Underground Research Laboratory in Bure. Higher swelling Pressure was found with the swell-consolidation method, the swelling Pressures determined by other methods being comparable. The swelling line that defined the swelling limit was lower than the consolidation curve, confirming the limitation of the swell-consolidation method in determining soil swelling Pressure. Moreover, the swelling Pressure corresponding to the in situ void ratio was expected to be 12 MPa–14 MPa, while the value corresponding to the sample void ratio after sampling was estimated between 0.3 and 1.9 MPa, much lower than the expected one. This large difference might be attributed to the claystone rebound due to unloading and claystone damage due to sampling. It could be also due to the natural material variability in terms of mineralogy and dry density. Further studies are, thus, needed for clarifying this point.
Michael Gaihede - One of the best experts on this subject based on the ideXlab platform.
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accuracy of tympanometric middle ear Pressure Determination the role of direction and rate of Pressure change with a fast modern tympanometer
Otology & Neurotology, 2005Co-Authors: Anette G Therkildsen, Michael GaihedeAbstract:HYPOTHESIS Modern tympanometers run at higher rates of Pressure change than older tympanometers, which increases the inaccuracy of determining the middle ear Pressure. BACKGROUND Tympanometric middle ear Pressure may be susceptible to both the direction as well as the rate of Pressure change, which is reflected by two different Pressure peaks in a bidirectional recording. The resulting peak Pressure difference results in an inaccuracy, which can amount to 25 daPa in older instruments with slower rates of Pressure change. However, modern instruments often apply much faster rates, which may increase the peak Pressure difference and thus the inaccuracy of middle ear Pressure. METHODS Middle ear Pressure was measured for a negative and positive direction of Pressure change at four different rates (50, 100, 200, and 400 daPa/s) in 38 normal adults. The peak Pressure difference was calculated by the middle ear Pressure determined in positive minus negative direction. RESULTS The mean peak Pressure differences ranged between 10 and 12 daPa (standard deviation = 8-11) in the four groups and were independent of the rate of Pressure change (p = 0.321). CONCLUSION The peak Pressure differences found by the current tympanometer were consistently small for all rates of Pressure change and were thus independent of the rate. This means that high rates can be used without decreasing accuracy, and the mean error is only 5 to 6 daPa, corresponding to the intrinsic hysteresis of the middle ear system.
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accuracy of tympanometric middle ear Pressure Determination in secretory otitis media dose dependent overestimation related to the viscosity and amount of middle ear fluid
Otology & Neurotology, 2005Co-Authors: Michael Gaihede, Mads Bramstoft, Lene T Thomsen, Aksel FoghAbstract:Hypothesis:Tympanometric measurements of middle ear Pressure in children with secretory otitis media are overestimated in a dose-response manner because of increased hysteresis explained by the viscosity and amount of middle ear fluid.Background:Tympanometric middle ear Pressure is important in eval
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middle ear volume and Pressure effects on tympanometric middle ear Pressure Determination model experiments with special reference to secretory otitis media
Auris Nasus Larynx, 2000Co-Authors: Michael GaihedeAbstract:Objective: Middle ear Pressure (Pm) measured by tympanometry has revealed high negative values in patients with secretory otitis media (SOM) in contrast to direct measurement. This may be explained by errors in tympanometry caused by volume displacement of the tympanic membrane (TM) affecting the volume of the middle ear (Vm) and the Pm according to Boyle’s Law. Such errors are susceptible to the size of Vm. Methods: A realistic middle ear model based on previous clinical studies of normal Pressure-volume relations of the middle ear system (MES) was constructed. In this model non-linear behaviour and hysteresis of the MES was imitated and Pm as well as Vm could be controlled. Results: Tympanometrically estimated Pm decreased on average 38 daPa, when Vm was changed from 21 to 1 cm3. The decrease was most pronounced, when Vm became smaller than 5 cm3. Moreover, tympanometry showed a linear numerical overestimation of Pm by a factor 2.31 compared with model Pm. Conclusion: A curve fit was derived describing the tympanometric Pm as a function of Vm. This demonstrated that tympanometric Pm approached −∞ daPa, when middle ear volume approached 0 cm3, which indicates that negative tympanometric recordings and B curves can be found in ears with normal Pm entirely due to very small Vm’s. This explains the discrepancy between direct and tympanometric measurements of Pm in SOM, since the effusion replaces the air filled expandable volume resulting in a very small ‘functional’ Vm. Numerical overestimation of Pm by tympanometry was explained by hysteresis, which reflected the viscoelastic properties of the MES. These results question the significance of negative Pm’s as a pathogenetic factor in SOM.
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tympanometric hysteresis effect and errors in middle ear Pressure Determination a preliminary study in children with secretory otitis media
Acta Oto-laryngologica, 2000Co-Authors: Michael Gaihede, Mads Bramstoft, Karin Lambertsen, Audrius Kamarauskas, Aksel FoghAbstract:Previous tympanometric studies on middle ear Pressure (MEP) have revealed the hysteresis effect, which is illustrated in bidirectional tympanometries by the different peak Pressures for either direction. This leads to an error in Determination of MEP, which has been reported to be 10-25 daPa in normal ears, but experimental data have suggested that this error may be increased in ears with secretory otitis media (SOM). This was investigated in a group of 18 children with SOM by bidirectional tympanometries. The peak Pressure difference (PPD) was calculated and found to be 75 daPa in the group of SOM, which was significantly larger than in normal ears (mean=3 daPa) ( p <0.001). The maximum PPD in the SOM group was 205 daPa, indicating an error in MEP Determination of more than 100 daPa. Hysteresis is related to the viscous properties of the middle ear system, and the increased hysteresis in SOM ears can be explained by the additional viscosity of the middle ear effusion. In order to improve the accuracy of ...
B. W. Van Oudheusden - One of the best experts on this subject based on the ideXlab platform.
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PIV-based Pressure measurement
Measurement Science and Technology, 2013Co-Authors: B. W. Van OudheusdenAbstract:The topic of this article is a review of the approach to extract Pressure fields from flow velocity field data, typically obtained with particle image velocimetry (PIV), by combining the experimental data with the governing equations. Although the basic working principles on which this procedure relies have been known for quite some time, the recent expansion of PIV capabilities has greatly increased its practical potential, up to the extent that nowadays a time-resolved volumetric Pressure Determination has become feasible. This has led to a novel diagnostic methodology for determining the instantaneous flow field Pressure in a non-intrusive way, which is rapidly finding acceptance in an increasing variety of application areas. The current review describes the operating principles, illustrating how the flow-governing equations, in particular the equation of momentum, are employed to compute the Pressure from the material acceleration of the flow. Accuracy aspects are discussed in relation to the most dominating experimental influences, notably the accuracy of the velocity source data, the temporal and spatial resolution and the method invoked to estimate the material derivative. In view of its nature of an emerging technique, recently published dedicated validation studies will be given specific attention. Different application areas are addressed, including turbulent flows, aeroacoustics, unsteady wing aerodynamics and other aeronautical applications. © 2013 IOP Publishing Ltd.
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instantaneous planar Pressure field Determination around a square section cylinder based on time resolved stereo piv
Proceedings of the 14th International Symposium on Applications of Laser Techniques to Fluid Mechanics Lisbon Posrtugal 07-10 July 2008 paper No. 1259, 2008Co-Authors: R. Kat, B. W. Van Oudheusden, F ScaranoAbstract:This paper describes the Determination of instantaneous planar Pressure fields from TR-PIV on a stationary square-section cylinder, with the face normal to the flow, for ReD=9,500, where D is the chord. The results from this planar Pressure imaging (PPI) are compared with mean and fluctuating surface Pressure data obtained with a Pressure orifice and a surface-mounted microphone in two locations: at the lower surface and at the base of the model. The results for the lower surface of the model show agreement in both mean and fluctuating Pressure compared with the Pressure orifice and microphone data, and with previous studies. The results for the base show agreement for the mean Pressure and give a good prospect for instantaneous planar Pressure Determination.