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.
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Soare, Andreia-Cristina, Victor David, and Serban C. Moldoveanu. "Variation with Temperature of Phase Ratio in Reversed Phase HPLC for a Methanol/Water Mobile Phase." Chromatographia 84, no. 6 (April 1, 2021): 581–87. http://dx.doi.org/10.1007/s10337-021-04038-7.
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Tanase, Tanase. "Regime Mixing Ratio in Vacuum Dilute Phase Pneumatic Conveying Systems." Acta Universitatis Cibiniensis. Series E: Food Technology 18, no. 1 (June 1, 2014): 33–46. http://dx.doi.org/10.2478/aucft-2014-0004.
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Abstract This paper analyses some aspects of regime mixing ratio (RMR) in Vacuum Dilute Phase Pneumatic Conveying Systems in order to measure the energy efficiency of these systems. RMR variation curve profile is determined and the proportionality between Theoretical Mixing Ratio (TMR) and RMR is evaluated. The equation of the Characteristic Curve of the Ventilator type APRG-902/C is given. The profile of the RMR variation curve by specific load of the pipe is determined.
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Fan, Sichen, Jun Ruan, Dandan Liu, Xinliang Wang, Fan Yang, Yong Guan, Hui Zhang, Junru Shi, Yang Bai, and Shougang Zhang. "Phase Variation Measurement in Mach–Zehnder Interferometric Switch." Measurement Science Review 21, no. 6 (October 26, 2021): 180–84. http://dx.doi.org/10.2478/msr-2021-0024.
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Abstract Phase variations of the interrogation field lead to frequency shifts in Ramsey-type atomic clocks. This paper reports the development of a 300 MHz Mach–Zehnder (MZ) switch that effectively suppresses phase-transient effects. Similar to MZ interferometers, this radio-frequency (RF) MZ switch comprises two arms that are power- and phase-matched with each other. By inserting a PIN diode RF switch in one arm, the other arm remains undisturbed, freeing it of the phase transient. Trigger phase fluctuation measurements are implemented by using a lock-in amplifier to extract the in-phase and quadrature (I/Q) demodulation data. The results show that the extinction ratio of the RF MZ switch phase fluctuations is <5 μrad, which is significantly lower than that of a PIN (50 μrad). When applied to a cesium fountain clock, the RF MZ switch produces a frequency shift better than 1.73 × 10−16.
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Kim, Young Ho, Byung Tae Ahn, Hyo Sub Kim, Sang Jin Han, Chu Sik Park, Ki Kwang Bae, and Jong Gyu Lee. "Variation in the Volume Ratio of HIX Phase/H2SO4 Phase for Improvement of Phase Separation Efficiency in the Bunsen Reaction Section." Advanced Materials Research 550-553 (July 2012): 435–38. http://dx.doi.org/10.4028/www.scientific.net/amr.550-553.435.
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The H2SO4 phase and HIx phase solution produced from Bunsen reaction section in SI (Sulfur-iodine) process were supplied to the phase separator for the continuous operation of SI process. However, the separation of Bunsen products in the phase separator is difficult because an excess of HIx phase solution existed in the phase separator than the H2SO4 phase solution. Therefore, the additional supply of H2SO4 to the phase separator as the phase separation method was considered for improvement of phase separation efficiency. In this work, the variations in volume ratio and composition of each phase solution were examined after the Bunsen product mixing on the HIx phase/H2SO4 phase volume ratio. As the results, the variation in composition of products increases with increase of the HIx phase/H2SO4 phase volume ratio after mixing. It was also found that the high variations in composition and volume ratio of Bunsen products by mixing in the presence of excess HIx phase. From the results, we concluded that the phase separation method, additional supply of H2SO4 phase solution to the phase separator, is effective in Bunsen product separation when the variation in composition is little.
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Janot-Pacheco, E., N. V. Leister, A. D. de Souza, S. Jankov, A. M. Hubert, and M. Floquet. "Phase Variation and NRP Modes in Southern Be Stars." International Astronomical Union Colloquium 175 (2000): 248–51. http://dx.doi.org/10.1017/s0252921100055937.
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Abstractζ Ophiuchi and η Centauri are hot, rapidly rotating, southern Be stars showing multi-mode nonradial pulsations (nrp). We use high resolution, high signal-to-noise ratio spectroscopic observations of these objects to test the Telting and Schrijvers’ method (TS) of mode degree l and azimuthal order | m | estimation. In this method, these quantum numbers are calculated from the blue-to-red phase difference of the corresponding main frequency and its first harmonic, respectively. The phase differences were obtained withe the help of the Clean and Cleanest algorithms. Quantum numbers calculated with TS are compatible with those obtained with the Fourier Doppler method within the estimated errors. In the absence of other tools, the TS method can thus be used to estimate l and | m | with reasonably accuracy.
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Korotenko, Valentin, Sergei Grachev, Nelly Kushakova, and Semyon Mulyavin. "Assessment of the Influence of Water Saturation and Capillary Pressure Gradients on Size Formation of Two-Phase Filtration Zone in Compressed Low-Permeable Reservoir." Journal of Mining Institute 245 (December 2, 2020): 569–81. http://dx.doi.org/10.31897/pmi.2020.5.9.
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The paper examines the influence of capillary pressure and water saturation ratio gradients on the size of the two-phase filtration zone during flooding of a low-permeable reservoir. Variations of water saturation ratio s in the zone of two-phase filtration are associated with the pressure variation of water injected into the reservoir; moreover the law of variation of water saturation ratio s(r, t) must correspond to the variation of injection pressure, i.e. it must be described by the same functions, as the functions of water pressure variation, but be subject to its own boundary conditions. The paper considers five options of s(r, t) dependency on time and coordinates.
In order to estimate the influence of formation and fluid compressibility, the authors examine Rapoport – Lis model for incompressible media with a violated lower limit for Darcy’s law application and a time-dependent radius of oil displacement by water. When the lower limit for Darcy’s law application is violated, the radius of the displacement front depends on the value of capillary pressure gradient and the assignment of s function.
It is shown that displacement front radii contain coefficients that carry information about physical properties of the reservoir and the displacement fluid. A comparison of two-phase filtration radii for incompressible and compressible reservoirs is performed.
The influence of capillary pressure gradient and functional dependencies of water saturation ratio on oil displacement in low-permeable reservoirs is assessed.
It is identified that capillary pressure gradient has practically no effect on the size of the two-phase filtration zone and the share of water in the arbitrary point of the formation, whereas the variation of water saturation ratio and reservoir compressibility exert a significant influence thereupon.
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Jouquand, Céline, Violette Ducruet, and Pierre Giampaoli. "Partition coefficients of aroma compounds in polysaccharide solutions by the phase ratio variation method." Food Chemistry 85, no. 3 (May 2004): 467–74. http://dx.doi.org/10.1016/j.foodchem.2003.07.023.
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Xu, Dong, Chunning Ji, Yuchuan Bai, and Xiaolong Song. "Three-dimensional numerical investigation on the influence of geometric shape on flow in river bends." Journal of Hydroinformatics 19, no. 5 (May 5, 2017): 666–85. http://dx.doi.org/10.2166/hydro.2017.074.
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To investigate the influences of river bend geometry on flow structures, three-dimensional simulations were carried out. The influence of aspect ratio, channel sinuousness and curvature ratio were investigated. Simulation results show that with an increasing of channel aspect ratios, the streamwise variation of flow velocities decreases significantly, which is not the case for the spanwise direction. Simulation results also reveal the significant influence of the curvature ratio on the redistribution of primary flows. The streamwise variation of free-surface and bottom-wall velocities was compared and the phase differences between them was identified, which was described as anti-phase and out-of-phase patterns. Deep-water channels with an aspect ratio of 0.15 show significant phase-lag of flow velocities compared with channel geometry, this newly observed phenomenon implies the shift of the peak scouring point in fluvial river meanders. For the first time to our knowledge, the streamwise and spanwise variation of primary and secondary flow strength, as well as their spatial derivatives, are quantitatively provided, which are valuable for theoretical studies. It is also found that the widely adopted assumption that the streamwise velocity component is one order magnitude larger than the spanwise, is only valid for river bends with small curvatures and aspect ratios.
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YANG, HO DONG, and YOOL KWON OH. "EFFECT OF ULTRASONIC VIBRATIONS ON ACCELERATING HEAT TRANSFER OF PCM." International Journal of Modern Physics B 20, no. 25n27 (October 30, 2006): 4341–46. http://dx.doi.org/10.1142/s021797920604132x.
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This study presents the effect on accelerating heat transfer of phase change material (PCM) when the ultrasonic vibrations were applied. Applying ultrasonic waves in a medium may cause the flow velocity of the medium to increase: an effect known as acoustic streaming. Hence, the objective of the present study was to investigate the melting process of a PCM from a heated vertical wall for the following: one without ultrasonic vibration (natural melting) and the other ultrasonic vibrations. The heat flow was measured in the absence of and in the presence of acoustic streaming. The streaming created by ultrasonic vibrations was visualized by a particle image velocimetry (PIV) and a thermal infrared camera. The experimental results revealed that acoustic streaming could accelerate the melting process as much as 2.5 times. Also, total consumed electricity was saved about 2.3 ~ 2.8 Wh , compared to the rate of natural melting. Moreover, we investigate the relationship between acoustic pressure variations and enhancement of heat transfer applying for coupled finite element-boundary element method (Coupled FE-BEM) as a numerical analysis. From the result study, as the acoustic pressure increases, the higher enhancement ratio of heat transfer is obtained. In the end, acoustic pressure variations are related to the acceleration of heat transfer by ultrasonic vibrations.
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Abrahamson, Norman A., and Bruce A. Bolt. "The spatial variation of the phasing of seismic strong ground motion." Bulletin of the Seismological Society of America 75, no. 5 (October 1, 1985): 1247–64. http://dx.doi.org/10.1785/bssa0750051247.
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Abstract The amount and significance of observed spatial variations of the phasing of seismic strong ground motion are explored using synchronized accelerograms from a surface array of digital strong motion accelerometers. A dynamic response ratio is defined for a discrete linear structural system in order to measure the effect of spatial variations of the ground motion on the response of large structures with multiple seismic wave inputs. The response with differential phasing may differ significantly to that with traditional rigid base inputs. Measurements show that phase shifts in the ground motion recorded across the SMART 1 array in Taiwan can produce up to a 25 per cent reduction in the inphase response spectrum at 5 Hz for a structure spanning a distance of 200 m. The out-of-phase dynamic response ratio is 0.20 to 0.40 for a flexible structure with a period of 1 sec and a support spacing of 200 m. In order to analyze more fully the effect of multi-support input motions, the concept of a seismic phase response spectrum is developed to complement the usual Housner (amplitude) response spectrum. An efficient estimation algorithm is outlined using complex demodulation. Seismological phase response spectra would seem to have wide application for engineering design.
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K. Mishra, Rajendra, Om Prakash Gupta, Sudhir Trivedi, and Prakash Dubey. "RELATIVE STUDY OF COMPRESSION RATIO VARIATION WITH PRESSURE FOR NANOMATERIALS USING EOS." International Journal of Advanced Research 10, no. 12 (December 31, 2022): 1203–9. http://dx.doi.org/10.21474/ijar01/15958.
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A basic thermodynamical study of various nanomaterials has been done. Different Equation of states [EOS] (Tait, Shanker & Suzuki) have been applied and compared with the experimental result. An derived equation using thermodynamical approximation is used to investigate the isothermal compression and pressure dependency of bulk modulus of nanomaterials i.e. TiO2(rutile phase), MgO, CuO, 3C-SiC, Zr0.1Ti0.9O2, e-Fe, Rb3C60, Ge(13 nm).The acquired results are found to be in excellent accord with known experimental data, demonstrating the validity of the formulation utilized in this work.
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Kapelner, Adam, Abba Krieger, and William J. Blanford. "Optimal experimental designs for estimating Henry's law constants via the method of phase ratio variation." Journal of Chromatography A 1468 (October 2016): 183–91. http://dx.doi.org/10.1016/j.chroma.2016.08.049.
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Wang, Dongqi, Daiyin Yin, and Junda Wang. "Physicochemical Properties and its Variation Law of Microemulsion Phase When Microemulsion Flooding." E3S Web of Conferences 252 (2021): 02066. http://dx.doi.org/10.1051/e3sconf/202125202066.
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The composition change of microemulsion system in microemulsion flooding will inevitably cause the change of phase behavior. Microemulsion with different phase types directly affects its performance and displacement efficiency of microemulsion flooding. Therefore, in order to accurately describe this change, this paper, starting from the composition of microemulsion, gives the physicochemical properties characterization methods of microemulsion phase density, viscosity and interfacial tension, and simulates the change of physicochemical properties of microemulsion phase caused by microemulsion entering the high water-oil ratio zone in the process of flooding. The research results are of great significance for screening microemulsion systems and determining the displacement efficiency.
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Borgekov, Daryn B., Artem L. Kozlovskiy, Rafael I. Shakirzyanov, Ainash T. Zhumazhanova, Maxim V. Zdorovets, and Dmitriy I. Shlimas. "Properties of Perovskite-like Lanthanum Strontium Ferrite Ceramics with Variation in Lanthanum Concentration." Crystals 12, no. 12 (December 9, 2022): 1792. http://dx.doi.org/10.3390/cryst12121792.
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The purpose of this work is to study the effect of lanthanum (La) concentration on the phase formation, conductivity, and thermophysical properties of perovskite-like strontium ferrite ceramics. At the same time, the key difference from similar studies is the study of the possibility of obtaining two-phase composite ceramics, the presence of various phases in which will lead to a change in the structural, strength, and conductive properties. To obtain two-phase composite ceramics by mechanochemical solid-phase synthesis, the method of the component molar ratio variation was used, which, when mixed, makes it possible to obtain a different ratio of elements and, as a result, to vary the phase composition of the ceramics. Scanning electron microscopy, X-ray phase analysis, and impedance spectroscopy were used as research methods, the combination of which made it possible to comprehensively study the properties of the synthesized ceramics. Analysis of phase changes depending on lanthanum concentration change can be written as follows: (La0.3Sr0.7)2FeO4/LaSr2Fe3O8 → (La0.3Sr0.7)2FeO4/LaSr2Fe3O8/Sr2Fe2O5 → (La0.3Sr0.7)2FeO4/Sr2Fe2O5. Results of impedance spectroscopy showed that with an increase in lanthanum concentration from 0.10 to 0.25 mol in the synthesized ceramics, the value of the dielectric permittivity increases significantly from 40.72 to 231.69, the dielectric loss tangent increases from 1.07 to 1.29 at a frequency of 10,000 Hz, and electrical resistivity decreases from 1.29 × 108 to 2.37 × 107 Ω∙cm.
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Verma, Shaily, Prashant Khuraiya, and Rajni Soni. "A comparative study of parasympathetic function tests during different phases of menstrual cycle in young healthy females." International Journal of Research in Medical Sciences 6, no. 4 (March 28, 2018): 1197. http://dx.doi.org/10.18203/2320-6012.ijrms20180967.
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Background: The hormonal fluctuations that occur during normal menstrual cycle has profound influence on autonomic functions. This influence on autonomic nervous system may affect cardiovagal control. The aim of the study is to find out the variation of Parasympathetic function tests during different phases of menstrual cycle in young healthy females.Methods: The present study was carried out on 50 healthy female subjects with normal menstrual cycles between the ages of 18 to 25 years. Various non-invasive parasympathetic function tests during different phases of menstrual cycle were performed that include Resting heart rate (RHR), Heart rate variation during deep breathing (E:I Ratio), Heart rate response to standing (30:15 Ratio), Heart rate response to Valsalva maneuver (Valsalva Ratio). The results were analysed using ANOVA and student’s paired-t tests.Results: During the menstrual cycle, we found varied heart rate response with higher values towards the luteal phase, when compared to the follicular phase and the menstrual phase. There was a statistically significant difference in the heart rate parameters like resting heart rate, 30:15 ratio, valsalva ratio and E:I ratio during the three phases of menstrual cycle.Conclusions: The study concludes that there was statistically significant heart rate variability during three phases of the menstrual cycle, as observed by the increased sympathetic discharge in the luteal phase compared to the increased parasympathetic discharge in the follicular phase. The results of our study have emphasized the complexity of the relationship between ovarian steroids and various hemodynamic regulatory systems.
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Ke, Yi-En, and Yung-I. Chen. "Effects of Nitrogen Flow Ratio on Structures, Bonding Characteristics, and Mechanical Properties of ZrNx Films." Coatings 10, no. 5 (May 14, 2020): 476. http://dx.doi.org/10.3390/coatings10050476.
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ZrNx (x = 0.67–1.38) films were fabricated through direct current magnetron sputtering by a varying nitrogen flow ratio [N2/(Ar + N2)] ranging from 0.4 to 1.0. The structural variation, bonding characteristics, and mechanical properties of the ZrNx films were investigated. The results indicated that the structure of the films prepared using a nitrogen flow ratio of 0.4 exhibited a crystalline cubic ZrN phase. The phase gradually changed to a mixture of crystalline ZrN and orthorhombic Zr3N4 followed by a Zr3N4 dominant phase as the N2 flow ratio increased up to >0.5 and >0.85, respectively. The bonding characteristics of the ZrNx films comprising Zr–N bonds of ZrN and Zr3N4 compounds were examined by X-ray photoelectron spectroscopy and were well correlated with the structural variation. With the formation of orthorhombic Zr3N4, the nanoindentation hardness and Young’s modulus levels of the ZrNx (x = 0.92–1.38) films exhibited insignificant variations ranging from 18.3 to 19.0 GPa and from 210 to 234 GPa, respectively.
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Puspitasari, Dewi, Indarto, Purnomo, and Khasani. "Kerosene-Water Flow Pattern in T-Junction Vertical Diameter Ratio 0.5 (Variation of Inclination Branch)." Applied Mechanics and Materials 493 (January 2014): 306–12. http://dx.doi.org/10.4028/www.scientific.net/amm.493.306.
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The separation is one of the important processes in exploration and production oil technology. Phase separation across T-junction with orientation vertical up branch is simplicity method to achieve maximum efficiency, but useful information is rather limited. This paper is presented only for inlet flow pattern and T-junction flow pattern of kerosene water mixture with inlet diameter 36 mm and branch diameter 19 mm (diameter ratio 0.5) on the variation inclination branch are 30o, 60oand 90o. Regulating flow by closing valve at downstream was done to obtain three flow resistance in the downstream. The flow pattern obtained in this study were : stratified (ST), three-layer-13 (3L-13) , three layer-2 (3L-2), and three layer-3 (3L-3). The results of the phase separation is best achieved under conditions inlet flow pattern stratified (ST) and T-junction three layer-3 (3L-3) flow pattern, angle 90°and downstream resistance 6471 Pa.Keywords: phase separation, T-junction, flow patterns, downstream resistance.
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Itahashi, Syuichi, Keiya Yumimoto, Itsushi Uno, Hiroshi Hayami, Shin-ichi Fujita, Yuepeng Pan, and Yuesi Wang. "A 15-year record (2001–2015) of the ratio of nitrate to non-sea-salt sulfate in precipitation over East Asia." Atmospheric Chemistry and Physics 18, no. 4 (February 28, 2018): 2835–52. http://dx.doi.org/10.5194/acp-18-2835-2018.
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Abstract. Acidifying species in precipitation can have severe impacts on ecosystems. The chemical composition of precipitation is directly related to the amount of precipitation; accordingly, it is difficult to identify long-term variation in chemical concentrations. The ratio of the nitrate (NO3−) to non-sea-salt sulfate (nss-SO42−) concentration in precipitation on an equivalent basis (hereinafter, Ratio) is a useful index to investigate the relative contributions of these acidifying species. To identify the long-term record of acidifying species in precipitation over East Asia, the region with the highest emissions worldwide, we compiled ground-based observations of the chemical composition of precipitation over China, Korea, and Japan from 2001 to 2015 based on the Acid Deposition Monitoring Network in East Asia (EANET). The spatial coverage was limited, but additional monitoring data for Japan, southern China, and northern China around Beijing were utilized. The period of analysis was divided into three phases: Phase I (2001–2005), Phase II (2006–2010), and Phase III (2011–2015). The behaviors of NO3− and nss-SO42− concentrations and hence the Ratio in precipitation were related to these precursors. The anthropogenic NOx and SO2 emissions and the NOx ∕ SO2 emission ratio were analyzed. Further, satellite observations of the NO2 and SO2 column density to capture the variation in emissions were applied. We found that the long-term trend in the NO3− concentration in precipitation was not related to the variation in NOx emission and the NO2 column. In comparison, the nss-SO42− concentration in precipitation over China, Korea, and Japan was partially connected to the changes in SO2 emissions from China, but the trends were not significant. The long-term trends of Ratio over China, Korea, and Japan were nearly flat during Phase I, increased significantly during Phase II, and were essentially flat again during Phase III. This variation in Ratio in East Asia clearly corresponded to the NOx ∕ SO2 emission ratio and the NO2 ∕ SO2 column ratio in China. The initial flat trend during Phase I was due to increases in both NOx and SO2 emissions in China, the significantly increasing trend during Phase II was triggered by the increase in NOx emissions and decrease in SO2 emissions in China, and the return to a flat trend during Phase III was caused by declines in both NOx and SO2 emissions in China. These results suggest that emissions in China had a significant impact not only on China but also on downwind precipitation chemistry during the 15-year period of 2001–2015. In terms of wet deposition, the NO3− wet deposition over China, Korea, and Japan did not change dramatically, but the nss-SO42− wet deposition declined over China, Korea, and Japan from Phase II to III. These declines were caused by a strong decrease in the nss-SO42− concentration in precipitation accompanied by a reduction in SO2 emission from China, which counteracted the increase in precipitation. These findings indicated that the acidity of precipitation shifted from sulfur to nitrogen.
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PATRA, B. K., C. P. SINGH, and F. C. KHANNA. "ISENTROPIC QUARK HADRON PHASE BOUNDARY AND STRANGENESS ENHANCEMENT." International Journal of Modern Physics A 15, no. 22 (September 10, 2000): 3563–75. http://dx.doi.org/10.1142/s0217751x00001312.
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We develop a phenomenological equation of state for the quark–gluon plasma containing nf flavors when the entropy per baryon ratio remains continuous across the phase boundary and thus derive a generalized expression for the temperature and baryon chemical potential dependent bag constant. The phase boundaries are obtained for an isentropic quark–hadron phase transition after using Gibbs' criteria and the transition to an ideal QGP from the solution of the condition B(μ,T)=0. The variation of critical temperature Tc with nf and the temperature variation of the quantity (ε-4P)/T4 which measures the interaction present in QGP are obtained and compared with the results from lattice calculations. Finally we obtain the strange particle ratios on the two phase boundaries which will be useful in identifying deconfined and/or ideal QGP formation in the heavy-ion experiments.
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Marcos, J. C., L. P. Fonseca, M. T. Ramalho, and J. M. S. Cabral. "Variation of penicillin acylase partition coefficient with phase volume ratio in poly(ethylene glycol)–sodium citrate aqueous two-phase systems." Journal of Chromatography B: Biomedical Sciences and Applications 711, no. 1-2 (June 1998): 295–99. http://dx.doi.org/10.1016/s0378-4347(97)00633-6.
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Yao, Yao Chun, Takayuki Watanabe, and Kazuyuki Yatsuda. "Discharge Behavior Characterization of 12-Phase AC Arc and its Application." Advanced Materials Research 479-481 (February 2012): 615–18. http://dx.doi.org/10.4028/www.scientific.net/amr.479-481.615.
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A stable 12-phase AC arc was successfully developed and applied in the field of glass in-flight melting, and the arc discharge behavior was characterized by image analysis. The effects of sheath gas flow rate on arc discharge and melting behavior of granulated glass raw material were investigated. Results show that different sheath gas flow rates lead to various arc discharge and high-temperature region. The fluctuation of luminance area ratio and coefficient of variation reflects the change of arc discharge behavior. As the sheath gas flow rate increases, the ratio of luminance area decreases and the center temperature of arc increases. The vitrification degree of glass raw material is mostly dependent on the center temperature of arc, higher center temperature and more vitrification degree.,A stable 12-phase AC arc was successfully developed and applied in the field of glass in-flight melting, and the arc discharge behavior was characterized by image analysis. The effects of sheath gas flow rate on arc discharge and melting behavior of granulated glass raw material were investigated. Results show that different sheath gas flow rates lead to various arc discharge and high-temperature region. The fluctuation of luminance area ratio and coefficient of variation reflects the change of arc discharge behavior. As the sheath gas flow rate increases, the ratio of luminance area decreases and the center temperature of arc increases. The vitrification degree of glass raw material is mostly dependent on the center temperature of arc, higher center temperature and more vitrification degree.
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Wang, A., D. Leparoux, O. Abraham, and M. Le Feuvre. "Frequency derivative of Rayleigh wave phase velocity for fundamental mode dispersion inversion: parametric study and experimental application." Geophysical Journal International 224, no. 1 (September 4, 2020): 649–68. http://dx.doi.org/10.1093/gji/ggaa417.
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SUMMARY Monitoring the small variations of a medium is increasingly important in subsurface geophysics due to climate change. Classical seismic surface wave dispersion methods are limited to quantitative estimations of these small variations when the variation ratio is smaller than 10 per cent, especially in the case of variations in deep media. Based on these findings, we propose to study the contributions of the Rayleigh wave phase velocity derivative with respect to frequency. More precisely, in the first step of assessing its feasibility, we analyse the effects of the phase velocity derivative on the inversion of the fundamental mode in the simple case of a two-layer model. The behaviour of the phase velocity derivative is first analysed qualitatively: the dispersion curves of phase velocity, group velocity and the phase velocity derivative are calculated theoretically for several series of media with small variations. It is shown that the phase velocity derivatives are more sensitive to variations of a medium. The sensitivity curves are then calculated for the phase velocity, the group velocity and the phase velocity derivative to perform quantitative analyses. Compared to the phase and group velocities, the phase velocity derivative is sensitive to variations of the shallow layer and the deep layer shear wave velocity in the same wavelength (frequency) range. Numerical data are used and processed to obtain dispersion curves to test the feasibility of the phase velocity derivative in the inversion. The inversion results of the phase velocity derivative are compared with those of phase and group velocities and show improved estimations for small variations (variation ratio less than 5 per cent) of deep layer shear wave velocities. The study is focused on laboratory experiments using two reduced-scale resin-epoxy models. The differences of these two-layer models are in the deep layer in which the variation ratio is estimated as 16.4 ± 1.1 per cent for the phase velocity inversion and 17.1 ± 0.3 per cent for the phase velocity derivative. The latter is closer to the reference value 17 per cent, with a smaller error.
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Tromelin, Anne, Charfedinne Ayed, Samuel Lubbers, Sandy Pagès-Hélary, Isabelle Andriot, and Elisabeth Guichard. "Proposed alternative phase ratio variation method for the calculation of liquid–vapour partition coefficients of volatiles." Journal of Chromatography A 1263 (November 2012): 158–68. http://dx.doi.org/10.1016/j.chroma.2012.09.039.
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Kuznetsov, Sergey V. "Abnormality of the longitudinal Pochhammer–Chree waves in the vicinity of C2 phase speed." Journal of Vibration and Control 24, no. 23 (March 14, 2018): 5642–49. http://dx.doi.org/10.1177/1077546318763205.
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The exact solutions of the linear Pochhammer–Chree equation for propagating harmonic waves in a cylindrical rod are analyzed. Spectral analysis of the matrix dispersion equation for longitudinal axially symmetric modes is performed and analytical expressions for displacement fields are obtained. The variation of wave polarization on the free surface due to the variation of Poisson’s ratio and circular frequency is analyzed. It is observed that at the phase speed coinciding with the bulk shear speed all the components of the displacement field vanish, meaning that no longitudinal axisymmetric Pochhammer–Chree waves can propagate at this phase speed.
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Yang, Xiao Bin, Zhuo Zhuang, and Xue Feng Yao. "Investigation into the Dynamic Fracture Properties of Large Scale Functionally Graded Materials." Key Engineering Materials 324-325 (November 2006): 239–42. http://dx.doi.org/10.4028/www.scientific.net/kem.324-325.239.
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A crack propagation perpendicular to gradient in a large scale functionally gradient materials, which has (1) a linear variation of Young’s modulus with a constant mass density and Poisson’s ratio, and (2) a exponential variation of Young’s modulus with a constant mass density and Poisson’s ratio, is modelled by finite element methods. Based on the experimental result of large scale functionally gradient materials, the dynamic propagation process of the FGMs is modelled and the dynamic parameters, like the energy release rate and crack tip opening angle, are calculated through a generation phase.
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Sutarno, Sutarno, and Yateman Arryanto. "PHASE TRANSFORMATION IN THE FORMATION OF FAUJASITE FROM FLY ASH." Indonesian Journal of Chemistry 5, no. 3 (June 15, 2010): 278–82. http://dx.doi.org/10.22146/ijc.21804.
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Faujasite was hydrothermally synthesized from fly ash at 100oC in alkaline solution by reflux with 5M HCl and fusion with NaOH pretreatments. Phase transformation in the formation of faujasite was performed by variation of NaOH/fly ash weight ratios and hydrothermal times. The solid products were characterized by X-ray diffraction method. Results showed that faujasite was formed through dissolution of fly ash components such as quartz, mullite and amorphous aluminosilicates followed by crystallization to form faujasite. Arranging the NaOH/fly ash weight ratio as well as hydrothermal time can selectively form faujasite. Faujasite with crystallinity of 97.06%, Si/Al ratio of 2.68, and specific surface area of 452.93 m2/g was successfully formed using NaOH/fly ash weight ratio of 1.2 for hydrothermal time of 72 hours. In more concentrated alkaline solution as well as for longer hydrothermal time, faujasite was completely transformed into hydroxysodalite as the final product. Keywords: fly ash, faujasite, and phase transformation.
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Chen, Zhou, Siyuan Chen, Xijun Ye, and Yunlai Zhou. "A Study on a Mechanism of Lateral Pedestrian-Footbridge Interaction." Applied Sciences 9, no. 23 (December 3, 2019): 5257. http://dx.doi.org/10.3390/app9235257.
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Based on the pedestrian lateral force hybrid Van der Pol/Rayleigh model, this study investigates the interaction dynamic model of a pedestrian-flexible footbridge lateral coupling system. A multi scale method is adopted to decouple the equation. The paper also studies the nonlinear dynamic response of the pedestrian-footbridge coupling system as well as the relationship between the lateral displacement of pedestrians and flexible footbridges, and the lateral interaction of the two variables. The results show that with the same frequency tuning parameters, when the mass ratio of pedestrians and footbridges is very small, the larger the mass ratio is, the larger the lateral response amplitude of pedestrians becomes. Conversely, when the mass ratio of pedestrians and footbridges is much larger, the larger the mass ratio is, the smaller the response amplitude becomes. When the natural frequency of a footbridge is larger, its Phase Angle becomes larger. As the lateral amplitude of pedestrians increases, the Phase Angle approaches zero. Moreover, regarding the variation of the Phase Angle between the interaction force and footbridge lateral vibration speed based on the lateral relative displacement of pedestrians, of which the variation range is (0, π ), as the pedestrians’ lateral amplitude increases, the Phase Angle approaches − π / 2 . The dynamic load coefficient varies linearly with the lateral amplitude of pedestrian vibrations.
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SONG, XIAOYUN, YAN LI, and SHUSUO LI. "EFFECT OF NI/TI RATIO ON THE MICROSTRUCTURE AND MECHANICAL PROPERTIES OF MO-DOPED NITIAL INTERMETALLICS." International Journal of Modern Physics B 24, no. 15n16 (June 30, 2010): 2694–99. http://dx.doi.org/10.1142/s0217979210065489.
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The microstructures and mechanical properties of Ni 50- x Ti 43+ x Al 6 Mo 1 ( x = 0.5, 1, 1.5, 3.5, 5.5 and 7 at. %) alloys have been investigated by X-ray diffraction (XRD), scanning electron microscope (SEM) and compressive tests. We found that the variation of Ni / Ti ratio is the predominant reason for affecting the yield stress. The yield stress at room temperature of Ni -rich and Ti -rich alloys was higher than that of the equi-atomic alloy due to the strong solid solution hardening caused by the variation of Ni / Ti ratio. The size and volume fraction of Ti 2 Ni phase decreased with increasing Ni / Ti ratio. The yield stress at 600°C and 700°C increased with the increasing volume fraction of Ti 2 Ni phase due to the precipitation hardening effect. The precipitation hardening effect was weakened with increasing temperature. For the Ti -rich alloy deformed at 800°C, the yield stress deceased with the increasing of Ni / Ti ratio due to the reduced strength and unfavorable distribution of Ti 2 Ni .
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Fan, Kai Min, Li Yang, Jing Tang, Qing Qiang Sun, and Xiao Tao Zu. "First-Principles Study of the Elastic Properties of Hexagonal Phase ScAx (A=H, He)." Advanced Materials Research 690-693 (May 2013): 1723–27. http://dx.doi.org/10.4028/www.scientific.net/amr.690-693.1723.
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First-principles calculations are performed to investigate the Young’s modulus, bulk modulus, shear modulus and Poisson’s ratio of hexagonal phase ScAx(A=H, He), where x=0, 0.0313, 0.125 and 0.25, represent the ratio of interstitial atoms A (A=H, He) to Sc atoms. The influences of hydrogen concentrations and helium concentrations on elastic modulus and Poisson’s ratio of ScAx(A=H, He) have been studied. The results indicate that hydrogen and helium have different effects on the elastic modulus of hexagonal phase scandium. The change mechanism of the Poisson’s ratio with the variation of the x ranging from 0 to 0.25 has also been studied in hexagonal phase ScAx(A=H, He). In addition, the changes in the charge densities of ScAxdue to the presence of hydrogen and helium have been calculated.
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Aşçı, Bürge, Şule Dinç Zor, and Özlem Aksu Dönmez. "Development and Validation of HPLC Method for the Simultaneous Determination of Five Food Additives and Caffeine in Soft Drinks." International Journal of Analytical Chemistry 2016 (2016): 1–8. http://dx.doi.org/10.1155/2016/2879406.
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Box-Behnken design was applied to optimize high performance liquid chromatography (HPLC) conditions for the simultaneous determination of potassium sorbate, sodium benzoate, carmoisine, allura red, ponceau 4R, and caffeine in commercial soft drinks. The experimental variables chosen were pH (6.0–7.0), flow rate (1.0–1.4 mL/min), and mobile phase ratio (85–95% acetate buffer). Resolution values of all peak pairs were used as a response. Stationary phase was Inertsil OctaDecylSilane- (ODS-) 3V reverse phase column (250 × 4.6 mm, 5 μm) dimensions. The detection was performed at 230 nm. Optimal values were found 6.0 pH, 1.0 mL/min flow rate, and 95% mobile phase ratio for the method which was validated by calculating the linearity (r2>0.9962), accuracy (recoveries ≥ 95.75%), precision (intraday variation ≤ 1.923%, interday variation ≤ 1.950%), limits of detection (LODs), and limits of quantification (LOQs) parameters. LODs and LOQs for analytes were in the range of 0.10–0.19 μg/mL and 0.33–0.63 μg/mL, respectively. The proposed method was applied successfully for the simultaneous determination of the mixtures of five food additives and caffeine in soft drinks.
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Liu, Yinghui, Dong Zhen, Huibo Zhang, Hao Zhang, Zhanqun Shi, and Fengshou Gu. "Vibration Response of the Planetary Gears with a Float Sun Gear and Influences of the Dynamic Parameters." Shock and Vibration 2020 (August 4, 2020): 1–17. http://dx.doi.org/10.1155/2020/8886066.
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Planetary gearboxes are widely used in mechanical transmission systems due to their large transmission ratio and high transmission efficiency. In a planetary gearbox, the sun gear is usually set to float to balance the sharing of loads among planet gears. However, this floating set will result in the variation of pressure angle, overlap ratio, and meshing phase in the meshing progress and when gear faults occur, the variation will be enlarged. In the previous studies, these parameters were reduced to constant. To study the influence of the dynamic parameters on the vibration response of planetary gearboxes under different operating conditions, a new lumped-parameter model containing the time-varying pressure angle (TVPA), time-varying overlap ratio (TVOR), and time-varying meshing phase (TVMP) is established. Based on this model, the vibration response mechanism of the sun gear is analyzed. Moreover, the comparison with the previous model is made and the rule of phase modulation caused by these dynamic parameters is revealed. By comparing the dynamic responses under different loads and rotation speeds, the phase modulation is studied in detail. Finally, the sun gear fault is introduced, and the phase modulation is analyzed in different fault degrees. This study can provide theoretical reference for the condition monitoring and fault diagnosis of planetary gearbox based on vibration analysis.
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Rai, Sachin, Navin Chaurasiya, and Pramod K. Yadawa. "Elastic, Mechanical and Thermophysical properties of Single-Phase Quaternary ScTiZrHf High-Entropy Alloy." Physics and Chemistry of Solid State 22, no. 4 (November 19, 2021): 687–96. http://dx.doi.org/10.15330/pcss.22.4.687-696.
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Consequent to the interaction potential model, the high-order elastic constants at high entropy alloys in single-phase quaternary ScTiZrHf have been calculated at different temperatures. Elastic constants of second order (SOECs) helps to determine other ultrasonic parameters. With the help of SOECs other elastic moduli, bulk modulus, shear modulus, Young’s modulus, Pugh’s ratio, elastic stiffness constants and Poisson’s ratio are estimated at room temperature for elastic and mechanical characterization. The other ultrasonic parameters are calculated at room temperature for elastic and mechanical characterization. The temperature variation of ultrasonic velocities along the crystal's z-axis is evaluated using SOECs. The temperature variation of the average debye velocity and the thermal relaxation time (τ) are also estimated along this orientation axis. The ultrasonic properties correlated with elastic, thermal and mechanical properties which is temperature dependent is also discussed. The ultrasonic attenuation due to phonon – phonon (p-p) interactions is also calculated at different temperatures. In the study of ultrasonic attenuation such as a function of temperature, thermal conductivity appears to be main contributor and p- p interactions are the responsible reason of attenuation and found that the mechanical properties of the high entropy alloy ScTiZrHf are superior at room temperature.
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Kolgjini, Blerina, Gustaaf Schoukens, and Paul Kiekens. "Three-Phase Characterization of Uniaxially Stretched Linear Low-Density Polyethylene." International Journal of Polymer Science 2011 (2011): 1–7. http://dx.doi.org/10.1155/2011/731708.
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This study comprises a detailed morphological study of cold-drawn polyethylene monofilaments by Raman spectroscopy, differential scanning calorimetry (DSC) and X-ray measurements. The structure of the three-phase morphology of the linear low-density polyethylene monofilaments was investigated by combining these measurements. It was found that the most important structure variation was found in the intermediate or rigid amorphous phase, whereby the amounts of crystalline and amorphous phases were nearly constant and almost independent of the cold-draw ratio. The intermediate third phase contains gauche and transmolecules, and the amount of transmolecules was increased with the cold-draw ratio and was directly related to this cold-draw ratio. It was found that the two peaks in the Raman spectra, respectively, at 1303 and 1295 cm-1, can be correlated to the amount of gauche and transmolecules in the polyethylene monofilaments. A good and new insight into the three-phase morphology was obtained by combining the DSC and X-ray measurements with the amounts of trans- and gauche molecules from the Raman spectra analysis.
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EL-Shamy, E. F., Emad K. El-Shewy, and Noura F. Abdo. "On the Higher-Order Phase Shift Contributions in Opposite Polarities Dust Plasmas." Zeitschrift für Naturforschung A 74, no. 6 (June 26, 2019): 489–97. http://dx.doi.org/10.1515/zna-2018-0386.
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AbstractThe collision of dressed dust acoustic solitons (DDASs) and the analytical higher-order phase shift are studied in a dusty plasma system that contains cold negative and positive dusty fluids and Maxwellian distributed for ions as well as electrons. The extended Poincaré–Lighthill–Kuo method is applied in order to obtain the nonlinear Korteweg–de Vries and phase shift equations, which admit the variation in soliton profiles and trajectories, respectively. Influences of the higher-order correction and the plasma fluid parameters such as charged dust grains concentration, negative-to-positive dust grain mass ratio, ion-to-negative dust grain number density ratio, and ion-to-electron temperature ratio on the characteristics of DDASs and their phase shifts are discussed. The comparisons between first- and higher-order contributions in rarefactive and compressive profiles are also taken into account. Furthermore, the present consideration may be utilised to mesosphere and magnetosphere.
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Joshi, Dilip S. "Latitudinal variation in locomotor activity rhythm in adult Drosophila ananassae." Canadian Journal of Zoology 77, no. 6 (October 10, 1999): 865–70. http://dx.doi.org/10.1139/z99-051.
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The parameters of the circadian rhythm of adult locomotor activity in strains of Drosophila ananassae originating between 6° and 34°N were variable and latitude-dependent. Two representative southern strains became active before sunrise, but one representative northern strain began activity after sunrise in nature. During entrainment to a 12 h light (L) : 12 h dark (D) cycle in the laboratory, the southern strains showed two peaks of activity, at the beginning and end of photophase, whereas the northern strains showed a single uninterrupted activity peak starting about 3 h after the lights-on. Among the strains, the phase angle difference (Ψ) during entrainment to 12 h L : 12 h D varied by about 5 h, the period of free-running rhythm(τ) in constant darkness by 3 h, the duration of the activity phase (α) by 7 h, and the duration of the resting phase (ρ) by 10 h. Lower latitude was correlated with an early Ψ (r = 0.977), a short τ (r = 0.975), a prolonged α (r = -0.995), a short ρ (r = 0.995) and a large α/ρ ratio (r = -0.963).
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Bai, Xu-Fang, Wei Xin, and Eerdunchaolu. "The influences of the dispersion and impurity on the properties of the Gaussian confining potential qubit with magnetic field." International Journal of Modern Physics B 33, no. 27 (October 30, 2019): 1950322. http://dx.doi.org/10.1142/s0217979219503223.
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The influences of the dispersion, the impurity and the electron–phonon coupling (EPC) on the properties of the Gaussian confining (GC) potential qubit with magnetic field were studied by Pekar-type variation method. Results show that the decoherence time will increase with increasing the dielectric constant (DC) ratio, the dispersion coefficient and the EPC strength, respectively. The phase rotation quality factor increases with increasing the dielectric constant ratio, the dispersion coefficient and EPC strength, respectively. The magnetic field has a regulatory effect on the decoherence time and the phase rotation quality factor.
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Ilyashenko, Alla V., and Sergey V. Kuznetsov. "Polarization of the Longitudinal Pochhammer–Chree Waves." Mechanics and Mechanical Engineering 22, no. 4 (September 2, 2020): 1329–36. http://dx.doi.org/10.2478/mme-2018-0103.
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AbstractThe exact solutions of the linear Pochhammer – Chree equation for propagating harmonic waves in a cylindrical rod, are analyzed. Spectral analysis of the matrix dispersion equation for longitudinal axially symmetric modes is performed. Analytical expressions for displacement fields are obtained. Variation of wave polarization on the free surface due to variation of Poisson’s ratio and circular frequency is analyzed. It is observed that at the phase speed coinciding with the bulk shear wave speed all the components of the displacement field vanish, meaning that no longitudinal axisymmetric Pochhammer – Chree wave can propagate at this phase speed.
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Huddleston, J. G., R. Wang, J. A. Flanagan, S. O'Brien, and A. Lyddiatt. "Variation of protein partition coefficients with volume ratio in poly(ethylene glycol)-salt aqueous two-phase systems." Journal of Chromatography A 668, no. 1 (May 1994): 3–11. http://dx.doi.org/10.1016/0021-9673(94)80086-3.
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Hu, Hui-Chao, Xin-Sheng Chai, and Donald Barnes. "Determination of solid–liquid partition coefficient of volatile compounds by solid phase ratio variation based headspace analysis." Fluid Phase Equilibria 380 (October 2014): 76–81. http://dx.doi.org/10.1016/j.fluid.2014.07.040.
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Kingsley, Robert A., Eric H. Weening, A. Marijke Keestra, and Andreas J. Bäumler. "Population Heterogeneity of Salmonella enterica Serotype Typhimurium Resulting from Phase Variation of the lpf Operon In Vitro and In Vivo." Journal of Bacteriology 184, no. 9 (May 1, 2002): 2352–59. http://dx.doi.org/10.1128/jb.184.9.2352-2359.2002.
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ABSTRACT The lpf fimbrial operon oscillates between phase ON and phase OFF expression states, thereby generating heterogeneity within S. enterica serotype Typhimurium populations with regard to expression of long polar fimbrial antigens. To determine whether the proportion of lpf phase variants changes with growth conditions, the lpf phase ON content of cultures was determined after in vitro and in vivo passage. After passage in Luria-Bertani (LB) broth for 120 generations, 96% of cells in a serotype Typhimurium culture carried the lpf operon in the phase ON expression state, regardless of the phase ON/OFF ratio in the inoculum. In contrast, a culture passaged on LB agar plates for 500 generations contained approximately 2% lpf phase ON cells. Differences in the lpf phase ON content of cultures passaged in broth and on plates were not caused by an outgrowth of lpf phase ON or lpf phase OFF cells, since deletion of lpf biosynthesis genes did not alter the phase ON/OFF ratio attained after passage. Instead, growth in LB broth resulted in a eightfold increase in the phase OFF-to-ON transition frequency and a decrease of the lpf phase ON-to-OFF transition frequency by a factor of 150 compared to growth on LB agar plates. After infection of naïve CBA/J mice with an lpf phase ON culture of serotype Typhimurium, the proportion of lpf phase ON cells continuously decreased over time, regardless of whether the strain carried intact fimbrial biosynthesis genes. These data suggest that elaboration of fimbriae does not have a major influence on the population heterogeneity produced by phase variation of the lpf operon in naïve mice.