Showing papers on "Pressure measurement published in 2008"

The transpiration of water at negative pressures in a synthetic tree

Abstract: Plant scientists believe that transpiration-the motion of water from the soil, through a vascular plant, and into the air-occurs by a passive, wicking mechanism. This mechanism is described by the cohesion-tension theory: loss of water by evaporation reduces the pressure of the liquid water within the leaf relative to atmospheric pressure; this reduced pressure pulls liquid water out of the soil and up the xylem to maintain hydration. Strikingly, the absolute pressure of the water within the xylem is often negative, such that the liquid is under tension and is thermodynamically metastable with respect to the vapour phase. Qualitatively, this mechanism is the same as that which drives fluid through the synthetic wicks that are key elements in technologies for heat transfer, fuel cells and portable chemical systems. Quantitatively, the differences in pressure generated in plants to drive flow can be more than a hundredfold larger than those generated in synthetic wicks. Here we present the design and operation of a microfluidic system formed in a synthetic hydrogel. This synthetic 'tree' captures the main attributes of transpiration in plants: transduction of subsaturation in the vapour phase of water into negative pressures in the liquid phase, stabilization and flow of liquid water at large negative pressures (-1.0 MPa or lower), continuous heat transfer with the evaporation of liquid water at negative pressure, and continuous extraction of liquid water from subsaturated sources. This development opens the opportunity for technological uses of water under tension and for new experimental studies of the liquid state of water.

Ruby under pressure

Abstract: The ruby luminescence method is widely used for pressure measurement in the diamond anvil cell and other optically transparent pressure cells. With this application in mind, we briefly review the ground-state physical properties of corundum (α-Al2O3) with some emphasis on its behavior under high pressure, survey the effects of temperature and stress on the R-line luminescence of ruby (Cr-doped corundum), and address the recent efforts towards an improved calibration of the R-line shift under hydrostatic pressures beyond the 50 GPa mark.

The near pressure field of co-axial subsonic jets

Abstract: Results are presented from pressure measurements performed in the irrotational near field of unbounded co-axial jets. Measurements were made for a variety of velocity and temperature ratios, and configurations both with and without serrations on the secondary nozzle lip. The principal objective of the study is to better understand the near pressure field of the jet, what it can tell us regarding the underlying turbulence structure, and in particular how it can be related to the source mechanisms of the flow.A preliminary analysis of the axial, temporal and azimuthal structure of the pressure field shows it to be highly organized, with axial spatial modes (obtained by proper orthogonal decomposition) which resemble Fourier modes. The effects of serrations on the pressure fluctuations comprise a global reduction in level, a change in the axial energy distribution, and a modification of the evolution of the characteristic time scales.A further analysis in frequency–wavenumber space is then performed, and a filtering operation is used to separate the convective and propagative footprints of the pressure field. This operation reveals two distinct signatures in the propagating component of the field: a low-frequency component which radiates at small angles to the flow axis and is characterized by extensive axial coherence, and a less-coherent high-frequency component which primarily radiates in sideline directions. The serrations are found to reduce the energy of the axially coherent propagating component, but its structure remains fundamentally unchanged; the high-frequency component is found to be enhanced. A further effect of the serrations involves a relative increase of the mean-square pressure level of the acoustic component – integrated over the measurement domain – with respect to the hydrodynamic component. The effect of increasing the velocity and temperature of the primary jet involves a relative increase in the acoustic component of the near field, while the hydrodynamic component remains relatively unchanged: this shows that the additional acoustic energy is generated by the mixing region which is produced by the interaction of the inner and the outer shear layers, whereas the hydrodynamic component of the near field is primarily driven by the outer shear layer.

Accuracy of mean arterial pressure and blood pressure measurements in predicting pre-eclampsia: systematic review and meta-analysis

Abstract: Objective To determine the accuracy of using systolic and diastolic blood pressure, mean arterial pressure, and increase of blood pressure to predict pre-eclampsia. Design Systematic review with meta-analysis of data on test accuracy. Data sources Medline, Embase, Cochrane Library, Medion, checking reference lists of included articles and reviews, contact with authors. Review methods Without language restrictions, two reviewers independently selected the articles in which the accuracy of blood pressure measurement during pregnancy was evaluated to predict pre-eclampsia. Data were extracted on study characteristics, quality, and results to construct 2×2 tables. Summary receiver operating characteristic curves and likelihood ratios were generated for the various levels and their thresholds. Results 34 studies, testing 60 599 women (3341 cases of pre-eclampsia), were included. In women at low risk for pre-eclampsia, the areas under the summary receiver operating characteristic curves for blood pressure measurement in the second trimester were 0.68 (95% confidence interval 0.64 to 0.72) for systolic blood pressure, 0.66 (0.59 to 0.72) for diastolic blood pressure, and 0.76 (0.70 to 0.82) for mean arterial pressure. Findings for the first trimester showed a similar pattern. Second trimester mean arterial pressure of 90 mm Hg or more showed a positive likelihood ratio of 3.5 (95% confidence interval 2.0 to 5.0) and a negative likelihood ratio of 0.46 (0.16 to 0.75). In women deemed to be at high risk, a diastolic blood pressure of 75 mm Hg or more at 13 to 20 weeks’ gestation best predicted pre-eclampsia: positive likelihood ratio 2.8 (1.8 to 3.6), negative likelihood ratio 0.39 (0.18 to 0.71). Additional subgroup analyses did not show improved predictive accuracy. Conclusion When blood pressure is measured in the first or second trimester of pregnancy, the mean arterial pressure is a better predictor for pre-eclampsia than systolic blood pressure, diastolic blood pressure, or an increase of blood pressure.

Textile Pressure Sensor Made of Flexible Plastic Optical Fibers.

Abstract: In this paper we report the successful development of pressure sensitive textile prototypes based on flexible optical fibers technology. Our approach is based on thermoplastic silicone fibers, which can be integrated into woven textiles. As soon as pressure at a certain area of the textile is applied to these fibers they change their cross section reversibly, due to their elastomeric character, and a simultaneous change in transmitted light intensity can be detected. We have successfully manufactured two different woven samples with fibers of 0.51 and 0.98 mm diameter in warp and weft direction, forming a pressure sensitive matrix. Determining their physical behavior when a force is applied shows that pressure measurements are feasible. Their usable working range is between 0 and 30 N. Small drifts in the range of 0.2 to 4.6%, over 25 load cycles, could be measured. Finally, a sensor array of 2 x 2 optical fibers was tested for sensitivity, spatial resolution and light coupling between fibers at intersections.

A Dual Luminescent Sensor Material for Simultaneous Imaging of Pressure and Temperature on Surfaces

Abstract: A novel kind of composite material for simultaneous luminescent determination of air pressure and temperature is presented. The dual sensor consists of a fluorinated platinum porphyrin complex (PtTFPP) as an oxygen-sensitive probe, and of the highly temperature-sensitive europium complex Eu(tta)3(dpbt) as temperature probe. Both are incorporated into different polymer microparticles to control response characteristics and to avoid interferences. Encapsulation of PtTFPP in poly(styrene-co-acrylonitrile) (PSAN) results in a broad dynamic range from 0.05 to 2.00 bar for pressure measurements. The europium complex was incorporated into poly(vinyl chloride) to reduce the cross sensitivity towards oxygen. This system represents a new class of luminescent sensor system, where the signals are separated via the different luminescence lifetimes of the indicators. It is possible to monitor the emission of the temperature-sensitive probe by means of time-resolved fluorescence imaging without interferences, because the luminescence lifetime of the temperature indicator is tenfold longer than that of the oxygen indicator. The temperature image can then be used to compensate cross sensitivity of the pressure indicator towards temperature. In combination with an appropriate time-resolved measurement technique, this material enables simultaneous imaging of pressure (or oxygen partial pressure) and temperature distributions on surfaces. It is distinguished from other approaches of dual pressure and temperature sensitive paints because it avoids the need of signal separation by application of different cameras or by use of different optical filters or light sources.

System and method for gas flow verification

Abstract: A gas flow rate verification apparatus is provided for shared use in a multiple tool semiconductor processing platform. The gas flow rate verification apparatus is defined to measure a pressure rate of rise and temperature within a test volume for determination of a corresponding gas flow rate. The apparatus includes first and second volumes, wherein the second volume is larger than the first volume. The apparatus also includes first and second pressure measurement devices, wherein the second pressure measurement device is capable of measuring higher pressures. Based on the target gas flow rate to be measured, either the first or second volume can be selected as the test volume, and either the first or second pressure measurement device can be selected to measure the pressure in the test volume. Configurability of the apparatus enables accurate measurement of gas flow rates over a broad range and in an time efficient manner.

Experimental Study of a Dual-Mode Scramjet Isolator

Abstract: A constant-area isolator was fabricated and tested in conjunction with a Mach 2 hydrogen-air combustor operating at a simulated Mach 5 flight enthalpy. Predicted isolator performance was validated through pressure measurements obtained via low-frequency pressure taps. The maximum pressure ratio measured in the combustor approached the design limit of 4.5. Scramjet operability, the range of equivalence ratios over which combustion was sustained without shock-inlet interaction, was improved to 0.06-0.32, as opposed to 0.32-0.37 without the isolator. For a given change in fuel equivalence ratio, the location of the shock train was easier to control with the isolator modification. Shock-train location repeatability was found to vary somewhat with equivalence ratio. Small fluctuations in the time-resolved pressure history indicated that the shock train was relatively temporally steady for a given equivalence ratio. High-frequency pressure measurements were within a 95% confidence interval of low-frequency pressure measurements. High-frequency results indicated that an increase in pressure and large pressure fluctuations occurred near the leading edge of the shock train. Power spectral analyses also indicated that there is significant variation in the frequency content of the pressure signal upstream and downstream of the shock-train leading edge. These results suggest that methods of shock-train leading-edge detection may be developed using pressure-time history characteristics other than the pressure magnitude.

Pressure-induced Magnetic Transition in a Single Crystal of YbCo2Zn20

Abstract: We have measured the electrical resistivity of a single crystal of YbCo 2 Zn 20 at pressures up to 2.37 GPa and at temperatures from 50 mK to 300 K. Above a critical pressure P c (∼1 GPa), we have found a resistivity anomaly at T M (∼0.15 K at 1 GPa) that increases with the pressure. At the ambient pressure, the system shows a nonmagnetic ground state described by the Fermi-liquid model. The T 2 coefficient of the electrical resistivity A strongly increases with the pressure upon approaching P c . However, in the vicinity of P c , the temperature dependence of the resistivity deviates from the Fermi-liquid description. These observations suggest that the application of hydrostatic pressure induces a magnetically ordered state for P ≥ P c and T ≤ T M .

Compression of single-crystal magnesium oxide to 118 GPa and a ruby pressure gauge for helium pressure media

Abstract: The pressure-volume equation of state (EoS) of single-crystal MgO has been studied in diamondanvil cells loaded with helium to 118 GPa and in a non-hydrostatic KCl pressure medium to 87 GPa using monochromatic synchrotron X-ray diffraction. A third-order Birch-Murnaghan fit to the nonhydrostatic P-V data (KCl medium) yields typical results for the initial volume, V0 = 74.698(7) A 3

Effects of Inlet Pressure and Octane Numbers on Combustion and Emissions of a Homogeneous Charge Compression Ignition (HCCI) Engine

Abstract: The influence of inlet pressure ( P in) and octane numbers on combustion and emissions of a homogeneous charge compression ignition (HCCI) engine was experimentally investigated. The tests were carried out in a modified four-cylinder direct injection diesel engine. Four fuels with different research octane number (RON) were used during the experiments: 90-RON, 93-RON, and 97-RON primary reference fuel (PRF) blend and a commercial gasoline, 94.1-RON(G). The inlet pressure conditions were set to give 0.1, 0.15, and 0.2 MPa of absolute pressure. The results indicate that, with the increase of inlet pressure, the start of combustion (SOC) advances and the cylinder pressure increases. The effects of the PRF octane number on SOC are weakened as the inlet pressure increased. However, the difference of SOC between gasoline and PRF is enlarged with the increase of the inlet pressure. The successful HCCI operating range is extended to the upper and lower load as the inlet pressure increased. The maximum achievable ...

An Improved Performance Poly-Si Pirani Vacuum Gauge Using Heat-Distributing Structural Supports

Abstract: A new micro-Pirani vacuum gauge that employs a ladder-shaped structure with two parallel bridges and crosslinks in between has been designed and fabricated. This design enhances the physical performance of the gauge by increasing structural rigidity, thus allowing for longer beams and a wider selection of materials, and by allowing for better heat distribution across the sensor - therefore improving the full-scale range of sensor response. Furthermore, this Pirani gauge can be fabricated in a one-, two-, or three-mask process without postprocessing steps such as KOH etching. In a CMOS-compatible process, poly-Si 4 times 2 times 250-mum and 4 times 2 times 1000-mum Pirani gauges with the ladder structure were fabricated and tested with pressure ranges from 10-3 to 50 torr (0.133 to 1 times 103 Pa) and 5 times 10-2 to 760 torr (6.67 to 1.01 times 105-Pa atmospheric pressure) and with resolutions of approximately 10-3 and 5 times 10-2 (0.133 to 6.67 Pa), respectively. Constant temperature circuitry and thermoelectric temperature stabilization would further extend the range of operation and the resolution of these devices. Furthermore, these sensors operate at very low powers ranging from 300 to 600 muW depending on their geometry and pressure measurement range.

External mechanical pressure sensor for gastric band pressure measurements

Abstract: A merely exemplary external pressure sensing system comprises a connecting member and a pressure sensor. The connecting member is operable to connect to a syringe barrel and a needle. The connecting member comprises a conduit permitting communication of fluid from the syringe barrel to the needle when the connecting member is connected to the syringe barrel and the needle. The pressure sensor is in communication with the conduit. The pressure sensor is configured to sense pressure of fluid within the connecting member. The connecting member is configured to permit the pressure sensor to sense the pressure of the fluid while the fluid is communicated from the barrel to the needle. The pressure sensor is configured to provide a visual indication of sensed pressure. The visual indication may be provided by a variety of components, including but not limited to a diaphragm, a disc, a needle, or a slider.

In-Vitro and In-Vivo Trans-Scalp Evaluation of an Intracranial Pressure Implant at 2.4 GHz

Abstract: Elevation of intracranial pressure is one of the most important issues in neurosurgery and neurology in clinical practice. The prevalent techniques for measuring intracranial pressure require equipments that are wired, restricted to a hospital environment, and cause patient discomfort. A novel method for measuring the intracranial pressure is described. A wireless completely implantable device, operating at an industrial-scientific-medical band of 2.4 GHz, has been developed and tested. In-vitro and in-vivo evaluations are described to demonstrate the feasibility of microwave pressure monitoring through scalp, device integrity over a long period of time, and repeatability of pressure measurements. A distinction between an epidural and sub-dural pressure monitoring techniques is also described. Histo-pathological results obtained upon a long-term device implantation favor the utilization of the sub-dural pressure monitoring method. On the other hand, in-vivo studies illustrate a maximum pressure reading error of 0.8 mm middot Hg obtained for a sub-dural device with a capacitive microelectromechanical system sensor compared to 2 mm middot Hg obtained for an epidural device with a piezoresistive sensor.

Shock Train Leading-Edge Detection in a Dual-Mode Scramjet

Abstract: Time-resolved pressure measurements in a dual-mode scramjet isolator were examined to investigate the potential for using the measurements for shock train leading-edge detection. Changes in the pressure magnitude, standard deviation levels, and frequency content were observed as the shock train advanced upstream past each pressure measurement station. Three detection criteria were defined and examined: 1) 150% of the normalized pressure magnitude upstream of combustion influences, 2) 150% of the normalized pressure standard deviation level upstream of combustion influences, and 3) the maximum value of the normalized pressure standard deviation. Another method of shock train leading-edge detection involved the examination of the frequency content of the pressure signal using power spectra analysis. Results indicated that the second detection criterion provided the earliest method of shock train detection as the shock train moved upstream, followed by the first and third criteria. Also, the frequency content of the pressure signals significantly changed near the shock train leading edge. However, a comparison of this method to the three criteria first examined showed that it did not provide earlier shock train detection.

Fabrication and Characterization of a Wafer-Level MEMS Vacuum Package With Vertical Feedthroughs

Abstract: This paper reports a MEMS vacuum package with vertical feedthroughs formed in a glass substrate all at the wafer level. This approach satisfies requirements for MEMS vacuum packages, including small size, vacuum/hermetic capability, sealed and low parasitic feedthroughs, wafer-level processing, compatibility with most MEMS processes, and low cost. It also enables flip-chip solder attachment to a PC board. The package has an integrated micro-Pirani gauge on a glass substrate for in situ monitoring, a silicon cap, and vertical feedthroughs through the glass. The integrated Pirani gauge has 0.6 milli-torr resolution at 0.1 torr and 0.2 torr resolution at 100 torr. Using the Pirani gauge, the fabricated vacuum package is characterized. The package has maintained ~33 torr base pressure with plusmn1.5 torr uncertainty for more than four months without a getter. The long-term measured pressure uncertainty is from the measurement setup and environment, and can be improved using a getter inside the package. [2007-0160]

Multiplexed Fiber-Optic Pressure and Temperature Sensor System for Down-Hole Measurement

Abstract: A fiber Fabry-Perot (F-P) interferometer and a fiber Bragg grating (FBG) based pressure and temperature multiplexing sensor system is presented. This system is designed for high-temperature oil well down-hole permanent monitoring of pressure and temperature. Connecting a FBG temperature sensor and a F-P pressure sensor in series in the sensor head, the sensor system combines the advantages of simple structure of FBG for temperature sensing and high accuracy and low-temperature cross-sensitivity of F-P pressure sensor. Experimental results showed that the temperature measurement accuracy of 0.5degC and the long-term drift of the air gap of the F-P pressure sensor at 300degC is less than 0.1% within 300 h time span. This indicates that a long-term pressure measured accuracy of 0.03 MPa has been achieved in pressure gauge range of 0-30 MPa and in temperature variation range between 18degC to 300degC.

Cuffless Blood Pressure Monitoring Using Hydrostatic Pressure Changes

Abstract: This paper presents a new principle for noninvasive blood pressure measurements through a modified volume-oscillometric technique that eliminates an inflatable pressure cuff, and instead takes advantage of natural hydrostatic pressure changes caused by raising and lowering the subject's arm. This new methodology provides the distinct advantage of using an absolute gauge pressure reference for measurements, and does not necessarily require additional actuation.

Compression of single-crystal magnesium oxide to 118 GPa and a ruby pressure gauge for helium pressure media

Abstract: The pressure-volume equation of state (EoS) of single-crystal MgO has been studied in diamondanvil cells loaded with helium to 118 GPa and in a non-hydrostatic KCl pressure medium to 87 GPa using monochromatic synchrotron X-ray diffraction. A third-order Birch-Murnaghan fit to the nonhydrostatic P-V data (KCl medium) yields typical results for the initial volume, V0 = 74.698(7) A 3

Pressure control for vacuum processing system

Abstract: A pressure control system includes a digital communication network between a pressure sensor and a pressure controller. The digital communication network is configured to communicate signals between the pressure sensor and the pressure controller. The pressure sensor is configured to measure pressure within a vacuum chamber in a processing tool. The pressure controller is responsive to pressure measurements made by the pressure sensor and communicated to the pressure controller through the digital communication network, to control the pressure within the vacuum chamber so as to maintain the pressure in the vacuum chamber at a pressure set point received from the tool.

Flexible capacitive sensors for high resolution pressure measurement

Abstract: Thin, flexible, robust capacitive pressure sensors have been the subject of research in many fields where axial strain sensing with high spatial resolution and pressure resolution is desirable for small loads, such as tactile robotics and biomechanics. Simple capacitive pressure sensors have been designed and implemented on flexible substrates in general agreement with performance predicted by an analytical model. Two designs are demonstrated for comparison. The first design uses standard flex circuit technology, and the second design uses photolithography techniques to fabricate capacitive sensors with higher spatial and higher pressure resolution. Sensor arrays of varying sensor size and spacing are tested with applied loads from 0 to 1 MPa. Pressure resolution and linearity of the sensors are significantly improved with the miniaturized, custom fabricated sensor array compared to standard flexible circuit technology.

Shear force and pressure measurement in wearable textiles

Abstract: The invention refers to a sensor arrangement comprising at least one capacitance sensor for detecting a pressure and a shear force, wherein the capacitance sensor is integrated into a wearable textile, a method for measuring a shear force and a pressure by such a sensor arrangement, wherein the shear force and pressure is exerted on a skin of a person lying in a bed or sitting in a chair and to combinations and uses of the method. This described textile sensors allow for a simultaneous measurement of shear stress and pressure in anti decubitus textiles. This enhances risk assessment with regard to the development of bedsore ulcer.

Reinforced piezoresistive pressure sensor for ocean depth measurements

Abstract: Depth/pressure measurements in the ocean are of utmost importance to better understand the ocean processes, for maritime security and for tsunami wave detection. In this work, a reinforced piezoresistive pressure sensor with double diaphragms and Wheatstone bridges is proposed to achieve higher sensitivity, wider operating range and temperature compensation in ocean depth measurements. The reinforced design showed higher sensitivity (by 10–15%) and wider operating pressure capability (by 2–2.2 times) compared to the conventional single diaphragm piezoresistive design. The reinforced sensor design was validated by measuring the performance of a two-element pressure sensor, which showed sensitivity between 0.13 and 0.74 mV/(V psi) and a full scale span increased by approximately two times.

Biaxial Testing of Sheet Materials at High Strain Rates Using Viscoelastic Bars

Abstract: A dynamic bulge testing technique is developed to perform biaxial tests on metals at high strain rates. The main component of the dynamic testing device is a movable bulge cell which is directly mounted on the measuring end of the input bar of a conventional split Hopkinson pressure bar system. The input bar is used to apply and measure the bulging pressure. The experimental system is analyzed in detail and the measurement accuracy is discussed. It is found that bars made of low impedance materials must be used to achieve a satisfactory pressure measurement accuracy. A series of dynamic experiments is performed on aluminum 6111-T4 sheets using viscoelastic nylon bars to demonstrate the capabilities of the proposed experimental technique. The parameters of the rate-dependent Hollomon–Cowper–Symonds J2 plasticity model of the aluminum are determined using an inverse analysis method in conjunction with finite element simulations.

Closed loop control of exhaust system fluid dosing

Abstract: An exhaust line fuel injection system and associated methods of operation and control are disclosed. The fuel passes through a regulating valve connected to a pressurized fuel source and an outlet connected to an exhaust system fuel supply line. The exhaust system fuel supply line is connected to a nozzle, which generally comprises a check-valve and is configured to inject the fuel into the exhaust line. Using a pressure measuring device, an indication of the exhaust system fuel supply line pressure is obtained. A controller provides control over the flow regulating valve using feedback from the pressure indication and a predetermined relationship between the flow rate through the nozzle and one of the exhaust system fuel supply line pressure and the pressure drop across the nozzle. The method can be implemented with a single pressure measuring device. The same pressure measurements, especially their frequency spectrum, can be used to detect system faults.

Statistical structure of the fluctuating wall pressure and its in-plane gradients at high Reynolds number

Abstract: The fluctuating wall pressure and its gradients in the plane of the surface were measured beneath the turbulent boundary layer that forms over the salt playa of Utah's west desert. Measurements were acquired under the condition of near-neutral thermal stability to best mimic the canonical zero-pressure-gradient boundary-layer flow. The Reynolds number (based on surface-layer thickness, δ, and the friction velocity, uτ) was estimated to be 1 × 106 ± 2 × 105. The equivalent sandgrain surface roughness was estimated to be in the range 15≤ks+≤85. Pressure measurements acquired simultaneously from an array of up to ten microphones were analysed. A compact array of four microphones was used to estimate the instantaneous streamwise and spanwise gradients of the surface pressure. Owing to the large length scales and low flow speeds, attaining accurate pressure statistics in the present flow required sensors capable of measuring unusually low frequencies. The effects of imperfect spatial and temporal resolution on the present measurements were also explored. Relative to pressure, pressure gradients exhibit an enhanced sensitivity to spatial resolution. Their accurate measurement does not, however, require fully capturing the low frequencies that are inherent and significant in the pressure itself. The present pressure spectra convincingly exhibit over three decades of approximately −1 slope. Comparisons with low-Reynolds-number data support previous predictions that the inner normalized wall pressure variance increases logarithmically with Reynolds number. The wall pressure autocorrelation exhibits its first zero-crossing at an advected length that is between one tenth and one fifth of the surface-layer thickness. Under any of the normalizations investigated, the present surface vorticity flux intensity values are difficult to reconcile with low-Reynolds-number data trends. Inner variables, however, do yield normalized flux intensity values that are of the same order of magnitude at low and high Reynolds number. Spectra reveal that even at high Reynolds number, the primary contributions to the pressure gradient intensities occur over a relatively narrow frequency range. This frequency range is shown to be consistent with the scale of the sublayer pocket motions. In accord with low-Reynolds-number data, the streamwise pressure gradient signals at high Reynolds number are also characterized by statistically significant pairings of opposing sign fluctuations.

Automatic blood pressure measurement: the oscillometric waveform shape is a potential contributor to differences between oscillometric and auscultatory pressure measurements

Abstract: ObjectiveTo explore the differences between oscillometric and auscultatory measurements.MethodFrom a simulator evaluation of a non-invasive blood pressure (NIBP) device regenerating 242 oscillometric blood pressure waveforms from 124 subjects, 10 waveforms were selected based on the differences betw