Academic literature on the topic 'Phase ratio variation (PRV)'
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Journal articles on the topic "Phase ratio variation (PRV)"
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Yuan, Junjun, Shanshi Zhou, Xiaogong Hu, Long Yang, Jianfeng Cao, Kai Li, and Min Liao. "Impact of Attitude Model, Phase Wind-Up and Phase Center Variation on Precise Orbit and Clock Offset Determination of GRACE-FO and CentiSpace-1." Remote Sensing 13, no. 13 (July 5, 2021): 2636. http://dx.doi.org/10.3390/rs13132636.
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Currently, low Earth orbit (LEO) satellites are attracting great attention in the navigation enhancement field because of their stronger navigation signal and faster elevation variation than medium Earth orbit (MEO) satellites. To meet the need for real-time and precise positioning, navigation and timing (PNT) services, the first and most difficult task is correcting errors in the process of precise LEO orbit and clock offset determination as much as possible. Launched in 29 September 2018, the CentiSpace-1 (CS01) satellite is the first experimental satellite of LEO-based navigation enhancement system constellations developed by Beijing Future Navigation Technology Co. Ltd. To analyze the impact of the attitude model, carrier phase wind-up (PWU) and phase center variation (PCV) on precise LEO orbit and clock offset in an LEO-based navigation system that needs extremely high precision, we not only select the CS01 satellite as a testing spacecraft, but also the Gravity Recovery and Climate Experiment Follow-On (GRACE-FO). First, the dual-frequency global positioning system (GPS) data are collected and the data quality is assessed by analyzing the performance of tracking GPS satellites, multipath errors and signal to noise ratio (SNR) variation. The analysis results show that the data quality of GRACE-FO is slightly better than CS01. With residual analysis and overlapping comparison, a further orbit quality improvement is possible when we further correct the errors of the attitude model, PWU and PCV in this paper. The final three-dimensional (3D) root mean square (RMS) of the overlapping orbit for GRACE-FO and CS01 is 2.08 cm and 1.72 cm, respectively. Meanwhile, errors of the attitude model, PWU and PCV can be absorbed partly in the clock offset and these errors can generate one nonnegligible effect, which can reach 0.02~0.05 ns. The experiment results indicate that processing the errors of the attitude model, PWU and PCV carefully can improve the consistency of precise LEO orbit and clock offset and raise the performance of an LEO-based navigation enhancement system.
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Yang, Ho Dong, and Yool Kwon Oh. "Experimental and Numerical Study on Enhanced Heat Transfer of Solid-Liquid PCM by Ultrasonic Wave." Key Engineering Materials 326-328 (December 2006): 1145–48. http://dx.doi.org/10.4028/www.scientific.net/kem.326-328.1145.
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The present study is investigated the causes of enhanced heat transfer during the melting process of solid-liquid PCM (Phase Change Material) using an ultrasonic vibration. Paraffin (noctadecane) was selected as a PCM and experimental studies were performed as following. Heat transfer coefficient and enhancement ratio of heat transfer was measured, acoustic streaming induced by ultrasonic waves observed using a PIV (Particle Image Velocimetry) and thermally oscillating flow phenomenon observed using an infrared thermal camera during the melting process. For the numerical study, a coupled FE-BEM (Finite Element-Boundary Element Method) was applied to investigate acoustic pressure occurred by acoustic streaming in a medium. And then, the profiles of pressure variation compared with the enhancement ratio of heat transfer. The results of this study revealed that ultrasonic vibrations accompanied the effects like acoustic streaming and thermally oscillating flow. Such effects are a prime mechanism in the overall melting process when ultrasonic vibrations are applied. Also, as the acoustic pressure occurred by acoustic streaming increases, the higher enhancement ratio of heat transfer is obtained.
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Huang, R. F., C. Y. Ho, and J. K. Chen. "Pulsatile Flow Patterns and Wall Shear Stresses in Arch of a Turn-Around Tube With/Without Stenosis." Journal of Mechanics 27, no. 1 (March 2011): 79–94. http://dx.doi.org/10.1017/jmech.2011.10.
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ABSTRACTThe temporal/spatial evolution processes of the flow pattern, velocity distribution, and wall shear stress of pulsatile water flows in the arch of 180o turn-around tubes with/without stenosis were experimentally studied by using the particle image velocimetry (PIV). Three transparent tubes made of glass were used: A tube without stenosis in the arch, a tube with a 25% stenosis at the inner wall of arch, and a tube with a 50% stenosis at the inner wall of arch. Here the percentage of stensis denoted the ratio between the stenosis height to inner diameter of arch in the diametral cross section across mid-arch of the central plane. The flow was provided by a pump which approximately simulated the pulsatile pressure waves of human heart beats. The systole to diastole time period ratio is set at 35%:65%. The Womersley parameter, Dean number, and time-averaged Reynolds number were 14, 2348, and 3500, respectively. In the arch of the turn-around tube without stenosis, no boundary layer separation was found during the systolic phase. The reverse flow and recirculation bubble appeared in the arch only during the diastolic phase. The inner wall of the arch experienced lower wall shear stress during the diastolic phase due to the formation of recirculation bubble and secondary flow. In the arch with stenosis, the boundary layer separated from the inner wall and formed a recirculation bubble downstream the stenosis during the systolic phase. Lower stenosis (25%) did not cause drastic variation of the wall shear stresses. At higher stenosis (50%), however, the wall shear stress around the inner wall downstream the stenosis became extraordinarily low, whereas the wall shear stress around the upstream region of the outer wall of the downstream branch of the tube became anomalously large.
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Hua, W., Z. M. Chen, C. Y. Jie, Y. Kondo, A. Hofzumahaus, N. Takegawa, K. D. Lu, et al. "Atmospheric hydrogen peroxide and organic hydroperoxides during PRIDE-PRD'06, China: their concentration, formation mechanism and contribution to secondary aerosols." Atmospheric Chemistry and Physics Discussions 8, no. 3 (June 3, 2008): 10481–530. http://dx.doi.org/10.5194/acpd-8-10481-2008.
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Abstract. Atmospheric hydrogen peroxide (H2O2) and organic hydroperoxides were measured from 18 to 30 July in 2006 during the PRIDE-PRD'06 campaign at Backgarden, a rural site located 48 km north of Guangzhou, a mega-city in southern China. A ground-based instrument was used as a scrubbing coil collector to sample ambient air, followed by on-site analysis by high-performance liquid chromatography (HPLC) coupled with post-column derivatization and fluorescence detection. The H2O2 mixing ratio over the 13 days ranged from below the detection limit to a maximum of 4.6 ppbv, with a mean (and standard deviation) of (1.26±1.24) ppbv during the daytime (08:00–20:00 LT). Methyl hydroperoxide (MHP), with a maximum of 0.8 ppbv and a mean (and standard deviation) of (0.28±0.10) ppbv during the daytime, was the dominant organic hydroperoxide. Other organic peroxides, including bis-hydroxymethyl hydroperoxide (BHMP), peroxyacetic acid (PAA), hydroxymethyl hydroperoxide (HMHP), 1-hydroxy-ethyl hydroperoxide (1-HEHP) and ethyl hydroperoxide (EHP), were detected occasionally. The concentration of H2O2 exhibited a pronounced diurnal variation on sunny days, with a peak mixing ratio in the afternoon (12:00–18:00 LT), but lacked an explicit diurnal cycle on cloudy days. Sometimes a second peak mixing ratio of H2O2 was observed during the evening, suggesting that H2O2 was produced by the ozonolysis of alkenes. The diurnal variation profile of MHP was, in general, consistent with that of H2O2. The estimation indicated that in the morning the H2O2 detected was formed mostly through local photochemical activity, with the rest probably attributable to vertical transport. It is notable that relatively high levels of H2O2 and MHP were found in polluted air. The unexpectedly high level of HO2 radicals detected in this region can account for the production of hydroperoxides, while the high level of NOx suppressed the formation of hydroperoxides significantly. High concentrations of hydroperoxides were detected in samples of rainwater collected in a heavy shower on 25 July when a typhoon passed through, indicating that a considerable mixing ratio of hydroperoxides, particularly MHP, resided above the upper boundary layer, which might be transported on a regional scale and further influence the redistribution of HOx and ROx radicals. It was found that hydroperoxides, in particular H2O2, play an important role in the formation of secondary sulfate in the aerosol phase, where the heterogeneous reaction might contribute substantially. A negative correlation between hydroperoxides and water-soluble organic compounds (WSOC), a considerable fraction of the secondary organic aerosol (SOA), was observed, providing field evidence for the importance of hydroperoxides in the formation of SOA found in previous laboratory studies. We suggest that hydroperoxides act as an important link between sulfate and organic aerosols, which needs further study and should be considered in current atmospheric models.
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Hua, W., Z. M. Chen, C. Y. Jie, Y. Kondo, A. Hofzumahaus, N. Takegawa, C. C. Chang, et al. "Atmospheric hydrogen peroxide and organic hydroperoxides during PRIDE-PRD'06, China: their concentration, formation mechanism and contribution to secondary aerosols." Atmospheric Chemistry and Physics 8, no. 22 (November 24, 2008): 6755–73. http://dx.doi.org/10.5194/acp-8-6755-2008.
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Abstract. Atmospheric hydrogen peroxide (H2O2) and organic hydroperoxides were measured from 18 to 30 July in 2006 during the PRIDE-PRD'06 campaign at Backgarden, a rural site located 48 km north of Guangzhou, a mega-city in southern China. A ground-based instrument was used as a scrubbing coil collector to sample ambient air, followed by on-site analysis by high-performance liquid chromatography (HPLC) coupled with post-column derivatization and fluorescence detection. The H2O2 mixing ratio over the 13 days ranged from below the detection limit to a maximum of 4.6 ppbv, with a mean (and standard deviation) of (1.26±1.24) ppbv during the daytime (08:00–20:00 LT). Methyl hydroperoxide (MHP), with a maximum of 0.8 ppbv and a mean (and standard deviation) of (0.28±0.10) ppbv during the daytime, was the dominant organic hydroperoxide. Other organic peroxides, including bis-hydroxymethyl hydroperoxide (BHMP), peroxyacetic acid (PAA), hydroxymethyl hydroperoxide (HMHP), 1-hydroxy-ethyl hydroperoxide (1-HEHP) and ethyl hydroperoxide (EHP), were detected occasionally. The concentration of H2O2 exhibited a pronounced diurnal variation on sunny days, with a peak mixing ratio in the afternoon (12:00–18:00 LT), but lacked an explicit diurnal cycle on cloudy days. Sometimes a second peak mixing ratio of H2O2 was observed during the evening, suggesting that H2O2 was produced by the ozonolysis of alkenes. The diurnal variation profile of MHP was, in general, consistent with that of H2O2. The estimation indicated that in the morning the H2O2 detected was formed mostly through local photochemical activity, with the rest probably attributable to vertical transport. It is notable that relatively high levels of H2O2 and MHP were found in polluted air. The unexpectedly high level of HO2 radicals detected in this region can account for the production of hydroperoxides, while the moderate level of NOx suppressed the formation of hydroperoxides. High concentrations of hydroperoxides were detected in samples of rainwater collected in a heavy shower on 25 July when a typhoon passed through, indicating that a considerable mixing ratio of hydroperoxides, particularly MHP, resided above the boundary layer, which might be transported on a regional scale and further influence the redistribution of HOx and ROx radicals. It was found that hydroperoxides, in particular H2O2, play an important role in the formation of secondary sulfate in the aerosol phase, where the heterogeneous reaction might contribute substantially. A negative correlation between hydroperoxides and water-soluble organic compounds (WSOC), a considerable fraction of the secondary organic aerosol (SOA), was observed, possibly providing field evidence for the importance of hydroperoxides in the formation of SOA found in previous laboratory studies. We suggest that hydroperoxides act as an important link between sulfate and organic aerosols, which needs further study and should be considered in current atmospheric models.
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Erdem-Eraslan, Lale, Lonneke A. Gravendeel, Johan de Rooi, Paul H. C. Eilers, Ahmed Idbaih, Wim G. M. Spliet, Wilfred F. A. den Dunnen, et al. "Intrinsic Molecular Subtypes of Glioma Are Prognostic and Predict Benefit From Adjuvant Procarbazine, Lomustine, and Vincristine Chemotherapy in Combination With Other Prognostic Factors in Anaplastic Oligodendroglial Brain Tumors: A Report From EORTC Study 26951." Journal of Clinical Oncology 31, no. 3 (January 20, 2013): 328–36. http://dx.doi.org/10.1200/jco.2012.44.1444.
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Purpose Intrinsic glioma subtypes (IGSs) are molecularly similar tumors that can be identified based on unsupervised gene expression analysis. Here, we have evaluated the clinical relevance of these subtypes within European Organisation for Research and Treatment of Cancer (EORTC) 26951, a randomized phase III clinical trial investigating adjuvant procarbazine, lomustine, and vincristine (PCV) chemotherapy in anaplastic oligodendroglial tumors. Our study includes gene expression profiles of formalin-fixed, paraffin-embedded (FFPE) clinical trial samples. Patients and Methods Gene expression profiling was performed in 140 samples, 47 fresh frozen samples and 93 FFPE samples, on HU133_Plus_2.0 and HuEx_1.0_st arrays, respectively. Results All previously identified six IGSs are present in EORTC 26951. This confirms that different molecular subtypes are present within a well-defined histologic subtype. Intrinsic subtypes are highly prognostic for overall survival (OS) and progression-free survival (PFS). They are prognostic for PFS independent of clinical (age, performance status, and tumor location), molecular (1p/19q loss of heterozygosity [LOH], IDH1 mutation, and MGMT methylation), and histologic parameters. Combining known molecular (1p/19q LOH, IDH1) prognostic parameters with intrinsic subtypes improves outcome prediction (proportion of explained variation, 30% v 23% for each individual group of factors). Specific genetic changes (IDH1, 1p/19q LOH, and EGFR amplification) segregate into different subtypes. We identified one subtype, IGS-9 (characterized by a high percentage of 1p/19q LOH and IDH1 mutations), that especially benefits from PCV chemotherapy. Median OS in this subtype was 5.5 years after radiotherapy (RT) alone versus 12.8 years after RT/PCV (P = .0349; hazard ratio, 2.18; 95% CI, 1.06 to 4.50). Conclusion Intrinsic subtypes are highly prognostic in EORTC 26951 and improve outcome prediction when combined with other prognostic factors. Tumors assigned to IGS-9 benefit from adjuvant PCV.
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Hoff, Michael, U. Harlander, and C. Egbers. "Experimental survey of linear and nonlinear inertial waves and wave instabilities in a spherical shell." Journal of Fluid Mechanics 789 (January 25, 2016): 589–616. http://dx.doi.org/10.1017/jfm.2015.743.
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We experimentally study linear and nonlinear inertial waves in a spherical shell with a radius ratio of ${\it\eta}=1/3$. The shell rotates with a mean angular velocity ${\it\Omega}_{0}$ around its vertical axis. This rotation is overlaid by a time-periodic libration of the inner sphere in the range $0<{\it\omega}_{lib}<2{\it\Omega}_{0}$ to excite inertial waves with a defined frequency. In the first part, we investigate linear inertial waves. The influence of the libration amplitude and the libration frequency on the waves and further the efficiency of the forcing to excite linear inertial waves will be discussed. For this, qualitative data from Kalliroscope visualisation in a meridional laser plane, as well as quantitative particle image velocimetry (PIV) data in a horizontal plane, have been analysed. A simple two-dimensional ray-tracing model is applied for the meridional plane to interpret the visualisations with respect to energy focusing and wave attractors. For sufficiently high/low libration amplitudes/frequencies, the Stewartson layer, a vertical shear layer tangential to the inner sphere’s equator, becomes unstable. This so-called ‘supercritical’ regime, where centrifugal and shear instabilities occur, allows for nonlinear wave coupling. PIV analyses in the horizontal laser plane in the corotating frame show low-frequency structures that correspond to Rossby-wave instabilities of the Stewartson layer. Some of these are travelling retrograde and are trapped near the Stewartson layer, others are travelling prograde filling the whole gap outside the Stewartson layer. Since libration can be viewed as a time-periodic variation of differential rotation, we assume that these two different structures are related to either the retrograde $(Ro_{d}<0)$ or the prograde $(Ro_{d}>0)$ phase of the libration cycle. The experimental results confirm theoretical, numerical as well as other experimental studies on Stewartson-layer instabilities.
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Sareen, A., J. Zhao, D. Lo Jacono, J. Sheridan, K. Hourigan, and M. C. Thompson. "Vortex-induced vibration of a rotating sphere." Journal of Fluid Mechanics 837 (December 20, 2017): 258–92. http://dx.doi.org/10.1017/jfm.2017.847.
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Vortex-induced vibration (VIV) of a sphere represents one of the most generic fundamental fluid–structure interaction problems. Since vortex-induced vibration can lead to structural failure, numerous studies have focused on understanding the underlying principles of VIV and its suppression. This paper reports on an experimental investigation of the effect of imposed axial rotation on the dynamics of vortex-induced vibration of a sphere that is free to oscillate in the cross-flow direction, by employing simultaneous displacement and force measurements. The VIV response was investigated over a wide range of reduced velocities (i.e. velocity normalised by the natural frequency of the system): $3\leqslant U^{\ast }\leqslant 18$, corresponding to a Reynolds number range of $5000<Re<30\,000$, while the rotation ratio, defined as the ratio between the sphere surface and inflow speeds, $\unicode[STIX]{x1D6FC}=|\unicode[STIX]{x1D714}|D/(2U)$, was varied in increments over the range of $0\leqslant \unicode[STIX]{x1D6FC}\leqslant 7.5$. It is found that the vibration amplitude exhibits a typical inverted bell-shaped variation with reduced velocity, similar to the classic VIV response for a non-rotating sphere but without the higher reduced velocity response tail. The vibration amplitude decreases monotonically and gradually as the imposed transverse rotation rate is increased up to $\unicode[STIX]{x1D6FC}=6$, beyond which the body vibration is significantly reduced. The synchronisation regime, defined as the reduced velocity range where large vibrations close to the natural frequency are observed, also becomes narrower as $\unicode[STIX]{x1D6FC}$ is increased, with the peak saturation amplitude observed at progressively lower reduced velocities. In addition, for small rotation rates, the peak amplitude decreases almost linearly with $\unicode[STIX]{x1D6FC}$. The imposed rotation not only reduces vibration amplitudes, but also makes the body vibrations less periodic. The frequency spectra revealed the occurrence of a broadband spectrum with an increase in the imposed rotation rate. Recurrence analysis of the structural vibration response demonstrated a transition from periodic to chaotic in a modified recurrence map complementing the appearance of broadband spectra at the onset of bifurcation. Despite considerable changes in flow structure, the vortex phase ($\unicode[STIX]{x1D719}_{vortex}$), defined as the phase between the vortex force and the body displacement, follows the same pattern as for the non-rotating case, with the $\unicode[STIX]{x1D719}_{vortex}$ increasing gradually from low values in Mode I of the sphere vibration to almost $180^{\circ }$ as the system undergoes a continuous transition to Mode II of the sphere vibration at higher reduced velocity. The total phase ($\unicode[STIX]{x1D719}_{total}$), defined as the phase between the transverse lift force and the body displacement, only increases from low values after the peak amplitude response in Mode II has been reached. It reaches its maximum value (${\sim}165^{\circ }$) close to the transition from the Mode II upper plateau to the lower plateau, reminiscent of the behaviour seen for the upper to lower branch transition for cylinder VIV. Hydrogen-bubble visualisations and particle image velocimetry (PIV) performed in the equatorial plane provided further insights into the flow dynamics near the sphere surface. The mean wake is found to be deflected towards the advancing side of the sphere, associated with an increase in the Magnus force. For higher rotation ratios, the near-wake rear recirculation zone is absent and the flow is highly vectored from the retreating side to the advancing side, giving rise to large-scale shedding. For a very high rotation ratio of $\unicode[STIX]{x1D6FC}=6$, for which vibrations are found to be suppressed, a one-sided large-scale shedding pattern is observed, similar to the shear-layer instability one-sided shedding observed previously for a rigidly mounted rotating sphere.
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Bourgeois, J. A., B. R. Noack, and R. J. Martinuzzi. "Generalized phase average with applications to sensor-based flow estimation of the wall-mounted square cylinder wake." Journal of Fluid Mechanics 736 (November 6, 2013): 316–50. http://dx.doi.org/10.1017/jfm.2013.494.
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AbstractWe experimentally investigate the three-dimensional wake behind a finite wall-mounted square cylinder at $\mathit{Re}= 12\hspace{0.167em} 000$ and aspect ratio of 4. Focus is placed on the base flow and oscillatory fluctuation. Time-resolved three-dimensional velocity fields are constructed from high-frame-rate particle image velocimetry (PIV) and simultaneously recorded surface pressure measurements. All three velocity components are resolved in a rectangular near-wake region by two orthogonal dense arrays of parallel PIV planes. A key enabler is a generalized phase average incorporating a slowly varying base flow, a variable oscillation amplitude and higher harmonics. These generalizations reduce the instantaneous residual 30 % below those of a traditional phase average. Moreover, the resolved variations reveal analytical constraints of the mean flow and oscillation levels, such as the mean-field paraboloid. The proposed methodology for generalized phase averaging and for construction of three-dimensional velocity fields from two-dimensional PIV data is applicable to a large class of turbulent flows with oscillatory dynamics.
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Li, Lixun, Baiyu Li, Huaming Chen, and Feixue Wang. "Phase Errors Simulation Analysis for GNSS Antenna in Multipath Environment." International Journal of Antennas and Propagation 2015 (2015): 1–8. http://dx.doi.org/10.1155/2015/962627.
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High-precision GNSS application requires the exact phase center calibration of antenna. Various methods are published to determine the locations of the phase center. In the outfield, when the phase errors that arose by multipath exceed the phase center variations (PCV) tolerance, the calibration values may be not useful. The objective of this paper is thus to evaluate the phase errors that arose by multipath signals. An improved model of antenna receiving signal is presented. The model consists of three main components: (1) an antenna model created by combination of right hand circular polarization (RHCP) and left hand circular polarization (LHCP), (2) a multipath signals model including amplitude, phase, and polarization, and (3) a ground reflection model applying to circular polarization signals. Based on the model, two kinds of novel up-to-down(U/D)ratios are presented. The performance of the model is assessed against the impact of up-to-down ratio of antenna on phase errors.
Dissertations / Theses on the topic "Phase ratio variation (PRV)"
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Sanderson, Jessica. "Defining the impact of flavour interactions in protein based food matrices." Thesis, 2016. http://hdl.handle.net/2440/119438.
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Flavour is widely accepted as a major determinant of consumer satisfaction, so factors that influence flavour quality are of great interest to both food scientists and the manufacturing industry globally. Volatile organic compounds (VOC) play an important role in characterising the unique flavour profile of foods. However non-volatile matrix solutes are capable of selectively binding these compounds and modifying their availability for perception during consumption. The impact of carbohydrates and lipids has been extensively studied which has led to a comprehensive understanding of the principles governing their interaction with flavour volatiles. Proteins, in comparison, remain poorly understood. This is due mainly to their structural diversity and resulting range of available binding mechanisms which can change in response to environmental conditions such as those encountered during food processing. Myofibrillar proteins are compositionally significant components of skeletal muscle tissue and play a critical role in defining the textural properties of processed meat products including burgers and sausages. To determine their influence on flavour, a series of model solutions were analysed and partition coefficients Kg-m calculated to enable changes in compound volatility to be measured. Eleven different flavour volatiles were evaluated, including a number of plant derived bioactive compounds not previously considered in binding studies. Partition coefficients were measured using static headspace-gas chromatography (SH-GC) methods partnered with indirect phase ratio variation (PRV) techniques. The retention effect of myofibrillar proteins was quantified by reporting the percentage change in Kg-m following the introduction of protein extract into the system. Myofibrillar proteins were obtained from a series of extractions of pork loin fillet with sodium phosphate buffer. The process yielded 58.6 mg/g of muscle which accounted for an approximate recovery rate of 60% of total available proteins. Subsequent instrumental analysis confirmed that at 35°C, a 2 mg/mL protein extract was capable of binding all volatile compounds, to various degrees, reducing their volatility, or headspace concentration, and therefore the availability of each compound for sensory perception. The greatest effect was recorded for isomers citral and neral, with 55.9% and 59.1% retention reported respectively, followed by ethyl hexanote which gave 36.7% retention. Thymol and carvacrol followed closely, with 28.6% and 33.7% retention respectively. Data collected throughout the study strongly indicates that myofibrillar proteins interact predominantly via weak reversible associations that are enhanced with increasing levels of flavour compound hydrophobicity. Both SH-GC and PRV are commonly utilised in flavour interaction investigations and are known to have areas of limitation that must be considered throughout application. During instrumental method development however, a significant obstacle was encountered which had not been documented previously. After considerable method development, it was concluded that mass spectrometer (MS) detectors are not suitable for use in PRV trials due to the repeated injection of headspace water vapour into the system. This damaged MS components and limited the ionisation of analytes required for their detection.Thesis (MPhil) -- University of Adelaide, School of Agriculture, Food & Wine, 2016
Book chapters on the topic "Phase ratio variation (PRV)"
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Tromelin, Anne, Samuel Lubbers, Isabelle Andriot, and Elisabeth Guichard. "Improvement of Partition Coefficients Determination of Aroma Compounds in Food Matrices by the Phase Ratio Variation Method." In Flavour Science, 401–6. Elsevier, 2014. http://dx.doi.org/10.1016/b978-0-12-398549-1.00075-1.
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Savary, Géraldine, Jean-Louis Doublier, and Nathalie Cayot. "Phase ratio variation method as an efficient way to determine the partition coefficients of various aroma compounds in mixture." In Flavour Science - Recent Advances and Trends, 461–64. Elsevier, 2006. http://dx.doi.org/10.1016/s0167-4501(06)80109-3.
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Tkach, Alexander, and Paula M. Vilarinho. "Nonstoichiometry Role on the Properties of Quantum-Paraelectric Ceramics." In Structure Processing Properties Relationships in Stoichiometric and Nonstoichiometric Oxides. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.89499.
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Among the lead-free perovskite-structure materials, strontium titanate (SrTiO3—ST) and potassium tantalate (KTaO3—KT), pure or modified, are of particular importance. They are both quantum paraelectrics with high dielectric permittivity and low losses that can find application in tunable microwave devices due to a dependence of the permittivity on the electric field. Factors as Sr/Ti and K/Ta ratio in ST and KT ceramics, respectively, can alter the defect chemistry of these materials and affect the microstructure. Therefore, if properly understood, cation stoichiometry variation may be intentionally used to tailor the electrical response of electroceramics. The scientific and technological importance of the stoichiometry variation in ST and KT ceramics is reviewed and compared in this chapter. The differences in crystallographic phase assemblage, grain size, and dielectric properties are described in detail. Although sharing crystal chemical similarities, the effect of the stoichiometry is markedly different. Even if the variation of Sr/Ti and K/Ta ratios did not change the quantum-paraelectric nature of ST and KT, Sr excess impedes the grain growth and decreases the dielectric permittivity in ST ceramics, while K excess promotes the grain growth and increases the dielectric permittivity in KT ceramics.
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"THE VARIATION OF MOLAR VOLUME, COMPRESSION FACTOR, MOLAR ENTROPY, MOLAR ENTHALPY, MOLAR ISOBARIC HEAT CAPACITY, SPEED OF SOUND, HEAT CAPACITY RATIO, FUGACITY/PRESSURE RATIO AND ISENTHALPIC JOULE-THOMSON COEFFICIENT WITH TEMPERATURE AND PRESSURE IN THE SINGLE-PHASE REGION." In Chlorine, 73–119. Elsevier, 1985. http://dx.doi.org/10.1016/b978-0-08-030713-8.50020-5.
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"Nutrients in Salmonid Ecosystems: Sustaining Production and Biodiversity." In Nutrients in Salmonid Ecosystems: Sustaining Production and Biodiversity, edited by Thomas C. Kline. American Fisheries Society, 2003. http://dx.doi.org/10.47886/9781888569445.ch16.
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<em>Abstract.</em>—The amount of nitrogen contributed by anadromous and semelparous Pacific salmon <em>Oncorhynchus </em>spp., marine-derived nitrogen (MDN), relative to other sources, was estimated for sockeye salmon <em>O. nerka </em>juveniles rearing in nursery lakes of the Karluk and Kvichak rivers (Alaska) from their nitrogen stable isotope abundance using an isotope mixing model (IMM). Because trophic level (TL) as well as MDN can lead to nitrogen-15 enrichment, it is critical to know, for the IMM, the TL of juvenile sockeye salmon (JSS) during their lacustrine life history phase. The initial a priori TL of 3.0 overestimated MDN. Regressing salmon escapement with stable isotope ratio and incorporating an updated herbivore isotope fractionation factor suggested that the TL of Kvichak JSS was 3.7. This TL value and the difference in carbon and nitrogen stable isotope ratios between JSS and net Zooplankton suggested that theTL of net Zooplankton was 2.6. Using TL = 2.6 for net Zooplankton and the difference in stable isotope ratios between Karluk JSS and net Zooplankton suggested that JSS TL was 4.3. These latter TL values suggested that the mean MDN for the Karluk system during the late 1980s and early 1990s was 67%, which was approximately half of that predicted using earlier fractionation and TL values. Sample isotopic variation and variation due to instrument error were minor in comparison to TL uncertainty involved in data modeling. Nonetheless, nitrogen stable isotope data provide a means for assessing MDN that can range significantly within and among systems.
Conference papers on the topic "Phase ratio variation (PRV)"
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Cerri, Giovanni, Laila Chennaoui, Ambra Giovannelli, and Mauro Miglioli. "Further Developments of a Variable Fuel Flow Automatic Mixing Valve for Prescribed Injection Ratio." In ASME Turbo Expo 2009: Power for Land, Sea, and Air. ASMEDC, 2009. http://dx.doi.org/10.1115/gt2009-59035.
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The production of an emulsion by emulsification plant without the addition of chemical additives always requires an injection device of the dispersed phase (water or ethanol) into the continuous phase (fuel oil). In this way, a preliminary mixture of immiscible liquids is produced at the right volume ratio. Such a mixture is processed downstream to have an emulsion with the dispersed phase drop mean diameters less than 4 μm. Since Gas Turbines have a variable fuel flow related to the delivered power, there is the necessity of maintaining a prescribed dispersed phase to continuous phase volumetric ratio when the fuel flow varies. This paper deals with an automatic device that is capable of producing the prescribed injection ratio of the dispersed phase into the fuel oil when the fuel oil flow rate changes. Such a device is developed to be coupled with an emulsification system that provides to break an immiscible part of fluid in a very small drops. The system is for feeding fuel into engines (S.I. Gasoline, Diesel, Gas Turbine combustors) operating at variable loadings i.e variable liquid fuel flow. The mixer (PMD, Pre-Mixer Device) has been presented at ASME Turbo Expo (Montreal 2007) for diesel #2 operating at 25°C with the viscosity being assumed as constant because of its variation is in a reduced range. In this paper, different fuels having different viscosities (diesel oil of different numbers, rapeseed oil, sunflower oil, etc) have been tested. The major modeling aspect concerns with the behavior of the annular orifice that produces a membrane displacement. A bibliographic analysis has been performed and the main results are reported in this paper. Since the architecture of the orifice, its geometry and the flow conditions were not reported in the bibliography, systematic experiments have been performed. Such experiments have been carried on for various liquids having various viscosities for different geometric arrangements and force acting on the membrane. The analysis of results led to formulate models to describe both the discharge flow and effective force coefficients. The paper gives a complete outlook of the experiments and of the above models. The viscosity dependent models have been introduced in to the PMD simulation code. Such models that take the influence of viscosity into account have been developed and some scale-up rules have been established. An amply description of the sizing and scale-up models is presented together with modifications to improve the prototype behavior operated with fluids having different viscosities. Experimental results concerning the influence of viscosity of the continuous phase are presented and widely discussed taking the model as reference.
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Kananithikorn, Nardthida, and Teenarat Songsaeng. "Pre-Drilled ECD Design by Using Fracture Pressure Model in Satun-Funan Fields, Pattani Basin, Gulf of Thailand." In International Petroleum Technology Conference. IPTC, 2021. http://dx.doi.org/10.2523/iptc-21368-ms.
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Abstract Lost circulation is the most common drilling issue for infill drilling projects in Satun-Funan Fields, South Pattani Basin, Gulf of Thailand (GOT). The depleted sand is possible to be a root cause in many wells based on observation from resistivity time-lapse separation in depleted sands or shale nearby. Therefore, the objective of this study is to estimate fracture pressure related to the depleted sand and design an appropriate Equivalent Circulating Density (ECD) threshold for each well to avoid or minimize lost circulation and well control complication during drilling a new well. This study model is using Eaton (1969) equation. There are 3 input parameters which are Poisson's Ratio and pre-drilled estimated depletion pressure and depth. With limitations of no actual fracturing data and limited sonic log, the maximum ECD while lost circulation reading from Pressure While Drilling (PWD) tool and formation pressure test data were used to back-calculate for Poisson's Ratio and identified a relationship with depth. From the total of 68 wells in the Satun and Funan areas, the interpreted Poisson's Ratio ranges from 0.36 to 0.44 and its linear trend is apparently increasing with depth. To minimize the variation of back calculated Poisson's Ratio the local data become an important key for model validation and maintain the similarity of subsurface factors. This interpreted Poisson's ratio trend will be used to calculate for fracture pressure by incorporating with estimated depletion pressure and depth that expect to encounter in each planned well. The lowest fracture pressure in a planned well is used to prepare pre-drilled ECD management plan and a real-time well monitoring plan. Additionally, the model can be adjusted during the operational phase based on the new drilled well result. This alternative model was applied in 4 trial drilling projects in 2019 and fully implement in 6 drilling projects in 2020. The lost circulation can be prevented with value creation from expected gain reserves section is $57M and cost avoidance from non-productive time due to lost circulation is $3.4M. With an effort, good communication and great collaboration among cross-functional teams, the model success rate increases by 12%. However, there are some unexpected lost events occurred even though the maximum ECD lower than expected fracture pressure. This suspect as a combination of limitations and uncertainties on key input parameters and drilling parameters. In the future, the model is planned to expand to other gas fields in the Pattani Basin which will move to more infill phase and have higher chance of getting lost circulation to maximize benefits as the success case in Satun and Funan fields.
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Ergin, F. Go¨khan, Bo Beltoft Watz, Kaspars Erglis, and Andrejs Cebers. "Poor-Contrast Particle Image Processing in Microscale Mixing." In ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2010. http://dx.doi.org/10.1115/esda2010-24900.
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Particle image velocimetry (PIV) often employs the cross-correlation function to identify average particle displacement in an interrogation window. The quality of correlation peak has a strong dependence on the signal-to-noise ratio (SNR), or contrast of the particle images. In fact, variable-contrast particle images are not uncommon in the PIV community: Strong light sheet intensity variations, wall reflections, multiple scattering in densely-seeded regions and two-phase flow applications are likely sources of local contrast variations. In this paper, we choose an image pair obtained in a micro-scale mixing experiment with severe local contrast gradients. In regions where image contrast is sufficiently poor, the noise peaks cast a shadow on the true correlation peak, producing erroneous velocity vectors. This work aims to demonstrate that two image pre-processing techniques — local contrast normalization and Difference of Gaussian (DoG) filter — improve the correlation results significantly in poor-contrast regions.
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Balusamy, Saravanan, and Simone Hochgreb. "Comparison of Acoustic Velocity Perturbation Measurements Using PIV vs. Two-Microphone Technique." In ASME 2013 Gas Turbine India Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/gtindia2013-3512.
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Understanding combustion instabilities requires accurate measurements of the acoustic velocity perturbation into injectors. This is often accomplished via the use of the two microphone technique, as this only requires two pressure transducers. However, measurements of the actual velocities emerging from the injectors are not often taken, leaving questions regarding the assumptions about the acoustic velocity. A comparison of velocity measured at downstream of the injector with that of two-microphone technique can show the accuracy and limitations of two-microphone technique. In this paper, velocity measurements are taken using both particle image velocimetry (PIV) and the two-microphone technique in a high pressure facility designed for aeroengine injector measurements. The flow is excited using an area modulation device installed on the choked end of the combustion chamber, with PIV measurements enabled by optical access downstream of the injector through a quartz tube and windows. Acoustic velocity perturbations at the injector are determined by considering the Fourier transformed pressure fluctuations for two microphones installed at a known distance upstream of the injector. PIV measurements are realized by seeding the air flow with micrometric water particles under 2.5 bar pressure at ambient temperature. Phase locked velocity fields are realized by synchronizing the acquisition of PIV images with the revolution of the acoustic modulator using the pressure signal measured at the face of injector. The mean velocity fluctuation is calculated as the difference between maximum and minimum velocities, normalized by the mean velocity of the unforced case. Those values are compared with the peak-to-peak velocity fluctuation amplitude calculated by the two-microphone technique. Although the ranges of velocity fluctuations for both techniques are similar, the variation of fluctuation with forcing frequencies diverges significantly with frequency. The differences can be attributed to several limitations associated with of both techniques, such as the quality of the signal, the signal/noise ratio, the accuracy of PIV measurements and the assumption of isentropic flow of the particle velocity from the plenum through the injector. We conclude that two-microphone methods can be used as a reference value for the velocity fluctuation in low order applications such as flame transfer functions, but not for drawing conclusions regarding the absolute velocity fluctuations in the injector.
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Hart, Adam, and Lawrence Ukeiley. "Unsteady Aerodynamics on a Low Aspect Ratio Flat Plate." In ASME 2010 3rd Joint US-European Fluids Engineering Summer Meeting collocated with 8th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2010. http://dx.doi.org/10.1115/fedsm-icnmm2010-30846.
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The study of biological flight has shown the potential of using unsteady fluid mechanism to enhance lift and drag capabilities in low Reynolds number flight regimes. To help further the knowledge of unsteady aerodynamic fluid phenomena, a low aspect ratio flat plate is subjected to a pitching motion superimposed on a plunging motion. Variations in this motion are introduced by adding a phase lag to the pitching cycle relative to the plunge cycle. Particle Image Velocimetery (PIV) is used to measure the instantaneous velocity fields over the upper surface of the flat plate at several points in the motion cycle. These vector fields are then averaged over approximately 420 ensembles to obtain the mean velocity field at the points in the cycle. Three vortex detection algorithms are implemented to identify the center of the vortex structures created off the leading edge and track their convection downstream. Experiments show that phase lags between 75° and 90° are more prone to create organized vortex structures and convect them in close proximity to the upper surface of this low aspect ratio flat plate.
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Young, Bruce A., Richard J. Olson, and Jennifer M. O’Brian. "Validation of Fatigue Models for ERW Seam Weld Cracking." In ASME 2017 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/pvp2017-65378.
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In response to the National Transportation Safety Board (NTSB) Recommendation P-09-1, the Department of Transportation (DOT) Pipeline and Hazardous Material Safety Administration (PHMSA) initiated a comprehensive study to identify actions that could be implemented by pipeline operators to significantly reduce longitudinal seam failures in electric resistance weld (ERW) pipe. As part of the project, Task 4 in Phase II was designed to validate existing failure prediction models and, where gaps exist, refine or develop these models needed to assess and quantify defect severity for cold welds, hook cracks, and selective seam weld corrosion (SSWC) (the primary ERW/Flash Weld seam threats) for failure subject to loadings that develop both during hydrotests and in service. These models would then be used to develop software to support integrity management of seam welds with enough flexibility to benefit from the experience gained during this project. The purpose of this paper is to review the models used for fatigue crack growth rate (FCGR) calculations. Both the Willenborg Model, which is used to incorporate the retardation of crack growth after an overload occurs (such as a hydrostatic test in a pipeline), and the Walker Model, which is used to account for variation in stress ratio during the operation of a structure (i.e. pressure cycles in a liquid pipeline), will be discussed. Laboratory fatigue crack growth rate test results on several grades of pipe will be used to generate the constants employed in these models. The reports generated during the course of the project are publicly available and are located on the following PHMSA website: http://primis.phmsa.dot.gov/matrix/PriHome.rdm?pri=390.
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Kim, H. S., J. H. Jung, E. C. Nho, I. D. Kim, T. W. Chun, and H. G. Kim. "Power loss analysis of 3-phase voltage disturbance generator with variation of series transformer turn-ratio." In 2014 IEEE International Conference on Industrial Technology (ICIT). IEEE, 2014. http://dx.doi.org/10.1109/icit.2014.6894901.
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Keith, Brian D., Dipan K. Basu, and Charles Stevens. "Aerodynamic Test Results of Controlled Pressure Ratio Engine (COPE) Dual Spool Air Turbine Rotating Rig." In ASME Turbo Expo 2000: Power for Land, Sea, and Air. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/2000-gt-0632.
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The Controlled Pressure Ratio Engine (COPE) is a fourth generation variable cycle engine combining the attributes of a high temperature turbojet (high dry specific thrust and low Max power SFC) with those of a turbofan (low specific thrust and low part power SFC). Variation in turbine flow function is achieved by the Controlled Area Turbine (CAT) Nozzle concept, which utilizes an innovative cam driven scheme to achieve desired flow function changes while minimizing loss in aerodynamic performance. The single stage high pressure turbine is coupled with a two stage vaneless counter-rotating low pressure turbine. The COPE Turbine System Aero/Heat Transfer Design Validation Program, jointly conducted by GE Aircraft Engines and Allison Advanced Development Company under the direction of the Air Force Research Laboratory at Wright-Patterson Air Force Base, has succeeded in demonstrating advanced turbine technologies that will be utilized on the XTE76, XTE77, and Joint Strike Fighter engines. The various phases of this program evaluated variable area nozzle performance, high pressure turbine performance under the influence of varying flow function, and dual spool testing of the vaneless, counter-rotating low pressure turbine. Evaluation of the three phases demonstrated the aerodynamic capability of these turbine technologies, meeting pre-test predictions in overall and component efficiencies.
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Berthold, Arne, and Frank Haucke. "Influence of Excitation Frequency, Phase-Shift and Duty Cycle on Cooling Ratio in a Dynamically Forced Impingement Jet Array." In ASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/gt2019-90695.
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Abstract The cooling ratio on a dynamically forced 7×7 impingement jet array is studied experimentally. The current study is focused on determining the influence of a phase-shift between every row of nozzles as well as the impact of a duty cycle variation on the cooling ratio. Both parameters are studied in dependency of the impingement distance (H/D = 2, 3, 5), the (nozzle-)Reynolds-number (ReD = 3200, 5200, 7200) and the excitation frequency (f = 0 Hz – 1000 Hz). For every set of parameters, the phase-shift between every row of nozzles is varied between Φ = 0% – 90% while the variation of the duty-cycle is performed between DC = 35% – 65%. During all investigations, the dimensionless distance between adjacent nozzles is fixed at x/D = y/D = 5 and liquid crystal thermography is used to acquire the wall temperatures, which are further processed to calculate the local Nusselt numbers. Generally, the implementation of an excitation frequency allows a case depending increase in cooling ratio of up to 52%. Further implementation of a phase-shift yields an additional frequency-depending improvement of the cooling ratio. In case of duty cycle variation, the best case revealed an additional 19% improvement in cooling ratio.
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Kim, Namwon, Estelle T. Evans, Steven A. Soper, Michael C. Murphy, and Dimitris E. Nikitopoulos. "Investigation of Two-Phase Flow in Rectangular Micro-Channels." In ASME 2008 Fluids Engineering Division Summer Meeting collocated with the Heat Transfer, Energy Sustainability, and 3rd Energy Nanotechnology Conferences. ASMEDC, 2008. http://dx.doi.org/10.1115/fedsm2008-55037.
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This study addresses air-water, two-phase flows in micro-channels fabricated on poly-methyl-methacrylate (PMMA) with walls that are partially non-wetting (typical static contact angle 65° in stock form) and not molecularly smooth. Two different types of chips were prepared: Micro-milled micro-channels of aspect ratios 1, 2 and 3 with fixed hydraulic diameter on PMMA and micro-channels of unity aspect ratio replicated using hot embossing of PMMA with a micro-milled brass mold insert. Flow-maps obtained using the same gas-liquid injection geometry and method for the three aspect ratio micro-channels are presented, and regime boundaries are compared with those found by other investigations. The results indicate that the bubbly flow regime boundary is shifted to higher liquid and/or lower gas superficial velocities for the higher aspect ratio channels, while transition to the Annular and Annular-Dry regimes remains the same to within experimental uncertainty. The emphasis of what is presented is on the Segmented flow regime. Regular and irregular Segmented flow regimes of three types are assessed on the basis of the statistical variation in the associated phase length scales from flow observations over a substantial channel length. Comparison between results of the two different injection geometries and micro-channel manufacturing techniques indicate that feedback effects are a significant but not the only cause of segmented flow irregularity. The variability in the size of the liquid plug separating gas bubbles in Segmented flow is found to be substantially higher than that of the bubbles even when the flow is regular (low variability of bubble size). The average bubble length associated with a part of Segmented flows, regular and irregular alike is shown to scale approximately with the capillary number to the 2/3 power (liquid volumetric flow ratio to the −2/3). Irregular Segmented flow is favored by higher liquid superficial velocities, lower liquid volumetric flow ratios and lower channel aspect ratios. Of the three aspect ratios examined, the microchannel with aspect-ratio 3 displayed the broadest window of regular Segmented flow. Two-phase flow pressure drop was measured for test channels of unity aspect ratio. Each flow regime identified on the basis of topological observations is associated with different trends of the pressure drop variation with respect to volumetric flow ratio.