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Sample records for dynamic pressure measurements

  1. High Temperature Dynamic Pressure Measurements Using Silicon Carbide Pressure Sensors

    Science.gov (United States)

    Okojie, Robert S.; Meredith, Roger D.; Chang, Clarence T.; Savrun, Ender

    2014-01-01

    Un-cooled, MEMS-based silicon carbide (SiC) static pressure sensors were used for the first time to measure pressure perturbations at temperatures as high as 600 C during laboratory characterization, and subsequently evaluated in a combustor rig operated under various engine conditions to extract the frequencies that are associated with thermoacoustic instabilities. One SiC sensor was placed directly in the flow stream of the combustor rig while a benchmark commercial water-cooled piezoceramic dynamic pressure transducer was co-located axially but kept some distance away from the hot flow stream. In the combustor rig test, the SiC sensor detected thermoacoustic instabilities across a range of engine operating conditions, amplitude magnitude as low as 0.5 psi at 585 C, in good agreement with the benchmark piezoceramic sensor. The SiC sensor experienced low signal to noise ratio at higher temperature, primarily due to the fact that it was a static sensor with low sensitivity.

  2. Dynamic tire pressure sensor for measuring ground vibration.

    Science.gov (United States)

    Wang, Qi; McDaniel, James Gregory; Wang, Ming L

    2012-11-07

    This work presents a convenient and non-contact acoustic sensing approach for measuring ground vibration. This approach, which uses an instantaneous dynamic tire pressure sensor (DTPS), possesses the capability to replace the accelerometer or directional microphone currently being used for inspecting pavement conditions. By measuring dynamic pressure changes inside the tire, ground vibration can be amplified and isolated from environmental noise. In this work, verifications of the DTPS concept of sensing inside the tire have been carried out. In addition, comparisons between a DTPS, ground-mounted accelerometer, and directional microphone are made. A data analysis algorithm has been developed and optimized to reconstruct ground acceleration from DTPS data. Numerical and experimental studies of this DTPS reveal a strong potential for measuring ground vibration caused by a moving vehicle. A calibration of transfer function between dynamic tire pressure change and ground acceleration may be needed for different tire system or for more accurate application.

  3. Dynamic material strength measurement utilizing magnetically applied pressure-shear

    Directory of Open Access Journals (Sweden)

    Alexander C.S.

    2012-08-01

    Full Text Available Magnetically applied pressure-shear (MAPS is a recently developed technique used to measure dynamic material strength developed at Sandia National Laboratories utilizing magneto-hydrodynamic (MHD drive pulsed power systems. MHD drive platforms generate high pressures by passing a large current through a pair of parallel plate conductors which, in essence, form a single turn magnet coil. Lorentz forces resulting from the interaction of the self-generated magnetic field and the drive current repel the plates and result in a high pressure ramp wave propagating in the conductors. This is the principle by which the Sandia Z Machine operates for dynamic material testing. MAPS relies on the addition of a second, external magnetic field applied orthogonally to both the drive current and the self-generated magnetic field. The interaction of the drive current and this external field results in a shear wave being induced directly in the conductors. Thus both longitudinal and shear stresses are generated. These stresses are coupled to a sample material of interest where shear strength is probed by determining the maximum transmissible shear stress in the state defined by the longitudinal compression. Both longitudinal and transverse velocities are measured via a specialized velocity interferometer system for any reflector (VISAR. Pressure and shear strength of the sample are calculated directly from the VISAR data. Results of tests on several materials at modest pressures (∼10GPa will be presented and discussed.

  4. Dynamic surface pressure measurements on a square cylinder with pressure sensitive paint

    Energy Technology Data Exchange (ETDEWEB)

    McGraw, C.M.; Khalil, G.; Callis, J.B. [University of Washington, Department of Chemistry, Seattle, WA (United States); Bell, J.H. [Ames Research Center, National Aeronautics and Space Administration, Moffett Field, CA (United States)

    2006-02-01

    The dynamic and static surface pressure on a square cylinder during vortex shedding was measured with pressure sensitive paints (PSPs) at three angles of incidence and a Reynolds number of 8.9 x 10{sup 4}. Oscillations in the phosphorescence intensity of the PSP that occurred at the vortex shedding frequency were observed. From these phosphorescent oscillations, the time-dependent changes in pressure distribution were calculated. This work extends PSP's useful range to dynamic systems where oscillating pressure changes are on the order of 230 Pa and occur at frequencies in the range of 95-125 Hz. (orig.)

  5. A new dynamic method for measuring hydrogen partial pressure in molten aluminum alloy

    Directory of Open Access Journals (Sweden)

    Sun Qian

    2011-02-01

    Full Text Available Hydrogen partial pressure is an important parameter to calculate hydrogen concentration levels in molten aluminum alloy. A new dynamic method for measuring hydrogen partial pressure in molten aluminum alloy is studied. Dynamic and rapid measurement is realized through changing the volume of the vacuum chamber and calculating the pressure difference ΔP between the theoretical and measured pressures in the vacuum chamber. Positive ΔP indicates hydrogen transmits from melt to vacuum chamber and negative ΔP means the reverse. When ΔP is equal to zero, hydrogen transmitted from both sides reached a state of dynamical equilibrium and the pressure in the vacuum chamber is equal to the hydrogen partial pressure in the molten aluminum alloy. Compared with other existing measuring methods, the new method can significantly shorten the testing time and reduce measuring cost.

  6. A data base and analysis program for shuttle main engine dynamic pressure measurements

    Science.gov (United States)

    Coffin, T.

    1986-01-01

    A dynamic pressure data base management system is described for measurements obtained from space shuttle main engine (SSME) hot firing tests. The data were provided in terms of engine power level and rms pressure time histories, and power spectra of the dynamic pressure measurements at selected times during each test. Test measurements and engine locations are defined along with a discussion of data acquisition and reduction procedures. A description of the data base management analysis system is provided and subroutines developed for obtaining selected measurement means, variances, ranges and other statistics of interest are discussed. A summary of pressure spectra obtained at SSME rated power level is provided for reference. Application of the singular value decomposition technique to spectrum interpolation is discussed and isoplots of interpolated spectra are presented to indicate measurement trends with engine power level. Program listings of the data base management and spectrum interpolation software are given. Appendices are included to document all data base measurements.

  7. Towards a standard for the dynamic measurement of pressure based on laser absorption spectroscopy

    Science.gov (United States)

    Douglass, K. O.; Olson, D. A.

    2016-06-01

    We describe an approach for creating a standard for the dynamic measurement of pressure based on the measurement of fundamental quantum properties of molecular systems. From the linewidth and intensities of ro-vibrational transitions we plan on making an accurate determination of pressure and temperature. The goal is to achieve an absolute uncertainty for time-varying pressure of 5% with a measurement rate of 100 kHz, which will in the future serve as a method for the traceable calibration of pressure sensors used in transient processes. To illustrate this concept we have used wavelength modulation spectroscopy (WMS), due to inherent advantages over direct absorption spectroscopy, to perform rapid measurements of carbon dioxide in order to determine the pressure. The system records the full lineshape profile of a single ro-vibrational transition of CO2 at a repetition rate of 4 kHz and with a systematic measurement uncertainty of 12% for the linewidth measurement. A series of pressures were measured at a rate of 400 Hz (10 averages) and from these measurements the linewidth was determined with a relative uncertainty of about 0.5% on average. The pressures measured using WMS have an average difference of 0.6% from the absolute pressure measured with a capacitance diaphragm sensor.

  8. Towards a standard for the dynamic measurement of pressure based on laser absorption spectroscopy.

    Science.gov (United States)

    Douglass, K O; Olson, D A

    2016-06-01

    We describe an approach for creating a standard for the dynamic measurement of pressure based on the measurement of fundamental quantum properties of molecular systems. From the linewidth and intensities of ro-vibrational transitions we plan on making an accurate determination of pressure and temperature. The goal is to achieve an absolute uncertainty for time-varying pressure of 5 % with a measurement rate of 100 kHz, which will in the future serve as a method for the traceable calibration of pressure sensors used in transient processes. To illustrate this concept we have used wavelength modulation spectroscopy (WMS), due to inherent advantages over direct absorption spectroscopy, to perform rapid measurements of carbon dioxide in order to determine the pressure. The system records the full lineshape profile of a single ro-vibrational transition of CO2 at a repetition rate of 4 kHz and with a systematic measurement uncertainty of 12 % for the linewidth measurement. A series of pressures were measured at a rate of 400 Hz (10 averages) and from these measurements the linewidth was determined with a relative uncertainty of about 0.5 % on average. The pressures measured using WMS have an average difference of 0.6 % from the absolute pressure measured with a capacitance diaphragm sensor.

  9. Implications of Dynamic Pressure Transducer Mounting Variations on Measurements in Pyrotechnic Test Apparatus

    Science.gov (United States)

    Dibbern, Andreas; Crisafulli, Jeffrey; Hagopia, Michael; McDougle, Stephen H.; Saulsberry, Regor L.

    2009-01-01

    Accurate dynamic pressure measurements are often difficult to make within small pyrotechnic devices, and transducer mounting difficulties can cause data anomalies that lead to erroneous conclusions. Delayed initial pressure response followed by data ringing has been observed when using miniaturized pressure transducer mounting adapters required to interface transducers to small test chambers. This delayed pressure response and ringing, combined with a high data acquisition rate, has complicated data analysis. This paper compares the output signal characteristics from different pressure transducer mounting options, where the passage distance from the transducer face to the pyrotechnic chamber is varied in length and diameter. By analyzing the data and understating the associated system dynamics, a more realistic understanding of the actual dynamic pressure variations is achieved. Three pressure transducer mounting configurations (elongated, standard, and face/flush mount) were simultaneously tested using NASA standard initiators in closed volume pressure bombs. This paper also presents results of these pressure transducer mounting configurations as a result of a larger NASA Engineering and Safety Center pyrovalve test project. Results from these tests indicate the improved performance of using face/flush mounted pressure transducers in this application. This type of mounting improved initial pressure measurement response time by approximately 19 s over standard adapter mounting, eliminating most of the lag time; provided a near step-function type initial pressure increase; and greatly reduced data ringing in high data acquisition rate systems. The paper goes on to discuss other issues associated with the firing and instrumentation that are important for the tester to understand.

  10. Dynamic calibration of piezoelectric transducers for ballistic high-pressure measurement

    Directory of Open Access Journals (Sweden)

    Elkarous Lamine

    2016-01-01

    Full Text Available The development of a dynamic calibration standard for high-amplitude pressure piezoelectric transducers implies the implementation of a system which can provide reference pressure values with known characteristics and uncertainty. The reference pressure must be issued by a sensor, as a part of a measuring chain, with a guaranteed traceability to an international standard. However, this operation has not been completely addressed yet until today and is still calling further investigations. In this paper, we introduce an experimental study carried out in order to contribute to current efforts for the establishment of a reference dynamic calibration method. A suitable practical calibration method based on the calculation of the reference pressure by measurement of the displacement of the piston in contact with an oil-filled cylindrical chamber is presented. This measurement was achieved thanks to a high speed camera and an accelerometer. Both measurements are then compared. In the first way, pressure was generated by impacting the piston with a free falling weight and, in the second way, with strikers of known weights and accelerated to the impact velocities with an air gun. The aim of the experimental setup is to work out a system which may generate known hydraulic pressure pulses with high-accuracy and known uncertainty. Moreover, physical models were also introduced to consolidate the experimental study. The change of striker’s velocities and masses allows tuning the reference pressure pulses with different shapes and, therefore, permits to sweep a wide range of magnitudes and frequencies.

  11. [Validation of the Tekscan system for statistic and dynamic pressure measurements of the human femorotibial joint].

    Science.gov (United States)

    Wirz, D; Becker, R; Li, S Feng; Friederich, N F; Müller, W

    2002-01-01

    In vitro dynamic pressure measurements in the healthy and pathologically altered knee joint help to improve our understanding of the loading pattern on femorotibial surfaces. The aim of the study was to evaluate a piezoresistive pressure measuring system. A human cadaveric knee was mounted in a material-testing machine (Bionix 858) using a specially designed knee-holding device. Axial loading of the knee, flexed at 20o, at 500 N, 1000N and 1500 N was then carried out. For the static investigations, the piezoresistive measuring system (Tekscan), was compared with the FUJI measuring system. In addition, dynamic measurements were also performed with the Tekscan System. With the exception of the lateral compartment at a load of 1500 N, no differences in maximum pressures were observed between the two systems. Nor were there any differences with regard to contact surfaces, either in the medial or lateral compartment (p > 0.05). However, the reproducibility of the data was significantly higher with the Tekscan System (p Tekscan System proved to be more reliable than the FUJI System, and permits simultaneous measurements in both compartments. The Tekscan System is suitable for dynamic measurement of the femorotibial joint, and permits measurements to be made under more physiological conditions.

  12. Development of a Piezoelectric Polymer Film Pressure Transducer for Low Frequency and Dynamic Pressure Measurement

    Science.gov (United States)

    1990-12-01

    34pyro-", "piezo-" means "to press" in the Greek language and the piezoelectric effect is caused by applying pressure to the material. In 1881, the...LINKING THE BASIC * 180 ’CALL COMMANDS TO THE QUATECH MACHINE LANGUAGE 1 9 0 200 ADC.SETUP=&H3:SETCTM=&H6 210 SETC0=&H9 220 INADC12.B=&HC:SEGADDR...H3CA)+256*PEEK(&H3CB) 270 DEF SEG=CSEG2 280 GOSUB 330 ’QUATECH BOARD SETUP 290 GOSUB 860 ’DATA FILE SETUP 300 GOSUB 1010 ’ AQUIRE DATA 310 320 END 330

  13. Dynamic multi-planar EPI of the urinary bladder during voiding with simultaneous detrusor pressure measurement.

    Science.gov (United States)

    Simmons, A; Williams, S C; Craggs, M; Andrew, C; Gregory, L; Allin, M; Mundy, A; Leaker, B

    1997-01-01

    Magnetic resonance imaging gives high quality images of the urinary bladder with excellent contrast. We report here the first application of dynamic, multi-slice, echo planar imaging to a study of urinary bladder emptying. Changes in urinary bladder volumes and rates of urine expulsion from the bladder have been measured simultaneously with bladder pressure. The method shows promise for clinical applications involving compromised bladder function, for reappraising bladder contraction strength-volume relationships, and for investigating the rate of change of length, three-dimensional shape, and wall tension in different parts of the bladder during micturition.

  14. Shock tube investigation of dynamic response of pressure transducers for validation of rotor performance measurements

    Science.gov (United States)

    Bershader, Daniel

    1988-01-01

    For some time now, NASA has had a program under way to aid in the validation of rotor performance and acoustics codes associated with the UH-60 rotary-wing aircraft; and to correlate results of such studies with those obtained from investigations of other selected aircraft rotor performance. A central feature of these studies concerns the dynamic measurement of surface pressure at various locations up to frequencies of 25 KHz. For this purpose, fast-response gauges of the Kulite type are employed. The latter need to be buried in the rotor; they record surface pressures which are transmitted by a pipette connected to the gauge. The other end of the pipette is cut flush with the surface. In certain locations, the pipette configuration includes a rather sharp right-angle bend. The natural question has arisen in this connection: In what way are the pipettes modifying the signals received at the rotor surface and subsequently transmitted to the sensitive Kulite transducer element. The basic details and results of the program performed and recently completed in the High Pressure Shock Tube Laboratory of the Department of Aeronautics and Astronautics at Stanford University are given.

  15. Blood pressure measurement

    Science.gov (United States)

    Diastolic blood pressure; Systolic blood pressure; Blood pressure reading; Measuring blood pressure ... or your health care provider will wrap the blood pressure cuff snugly around your upper arm. The lower ...

  16. Dynamic high pressure measurements using a Fiber Bragg Grating probe and an arrayed waveguide grating spectrometer

    Science.gov (United States)

    Barbarin, Y.; Lefrançois, A.; Magne, S.; Woirin, K.; Sinatti, F.; Osmont, A.; Luc, J.

    2016-08-01

    High pressure shock profiles are monitored using a long Fiber Bragg Grating (FBG). Such thin probe, with a diameter of typically 150 μm, can be inserted directly into targets for shock plate experiments. The shocked FBG's portion is stressed under compression, which increases its optical group index and shortens its grating period. Placed along the 2D symmetrical axis of the cylindrical target, the second effect is stronger and the reflected spectrum shifts towards the shorter wavelengths. The dynamic evolution of FBG spectra is recorded with a customized Arrayed Waveguide Grating (AWG) spectrometer covering the C+L band. The AWG provides 40 channels of 200-GHz spacing with a special flattop design. The output channels are fiber-connected to photoreceivers (bandwidth: DC - 400 MHz or 10 kHz - 2 GHz). The experimental setup was a symmetric impact, completed in a 110-mm diameter single-stage gas gun with Aluminum (6061T6) impactors and targets. The FBG's central wavelength was 1605 nm to cover the pressure range of 0 - 8 GPa. The FBG was 50-mm long as well as the target's thickness. The 20-mm thick impactor maintains a shock within the target over a distance of 30 mm. For the impact at 522 m/s, the sustained pressure of 3.6 GPa, which resulted in a Bragg shift of (26.2 +/- 1.5) nm, is measured and retrieved with respectively thin-film gauges and the hydrodynamic code Ouranos. The shock sensitivity of the FBG is about 7 nm/GPa, but it decreases with the pressure level. The overall spectra evolution is in good agreement with the numerical simulations.

  17. A data base and analysis program for shuttle main engine dynamic pressure measurements. Appendix B: Data base plots for SSME tests 901-290 through 901-414

    Science.gov (United States)

    Coffin, T.

    1986-01-01

    A dynamic pressure data base and data base management system developed to characterize the Space Shuttle Main Engine (SSME) dynamic pressure environment is described. The data base represents dynamic pressure measurements obtained during single engine hot firing tesets of the SSME. Software is provided to permit statistical evaluation of selected measurements under specified operating conditions. An interpolation scheme is also included to estimate spectral trends with SSME power level. Flow dynamic environments in high performance rocket engines are discussed.

  18. A data base and analysis program for shuttle main engine dynamic pressure measurements. Appendix C: Data base plots for SSME tests 902-214 through 902-314

    Science.gov (United States)

    Coffin, T.

    1986-01-01

    A dynamic pressure data base and data base management system developed to characterize the Space Shuttle Main Engine (SSME) dynamic pressure environment is reported. The data base represents dynamic pressure measurements obtained during single engine hot firing tests of the SSME. Software is provided to permit statistical evaluation of selected measurements under specified operating conditions. An interpolation scheme is included to estimate spectral trends with SSME power level. Flow Dynamic Environments in High Performance Rocket Engines are described.

  19. [Dynamic measurement of pressure distribution with flexible measuring mats--an innovative measuring procedure in sports orthopedics and traumatology. Development--use--value].

    Science.gov (United States)

    Schaff, P; Hauser, W

    1987-12-01

    The results of this study provide the basis for an on-target use of measurement of pressure distribution with flexible mats in sports orthopaedics and traumatology and adjacent overlapping fields. Dynamic measurement of pressure distribution using a flexible mat as a capacitor can yield valuable additional information not available so far in this form, on the static and dynamic stress acting on the human locomotor system. In the future this method can be used to prevent injuries and to optimise performance in many disciplines of sport and will make a significant contribution to optimised treatment concepts with pressure-adjusted shoes or insoles, as well as to the control of functional surgery results in traumatology. The fundamentals are presented via a detailed description of the development, standardization and testing of this innovative measuring method. The questions of applicability, practicability and information supplied are discussed on the basis of extensive studies on reproducibility, on the amount of time and technical effort required for each measurement, and on a critical comparison with other methods. For the two fields of application presented here it was possible to standardize the working procedure enabling a largely problem-free application in practice. The first useful results were obtained in sports orthopaedics (alpine ski boots and sportshoe design). By applying the measuring of pressure distribution in alpine ski sports the influence the construction of ski boots on the stress exercised on the human leg could be objectively quantified in man for the first time. Marked differences were found between models where the heel can be turned down on entering, to conventionally fastened ski boots. This, as well as the results on the influence temperature, height of shaft and shaft stability or rigidity on the pressure distribution along the tibia, provide the basis for a new guideline for the testing of ski boots. A new method was developed for the

  20. A data base and analysis program for shuttle main engine dynamic pressure measurements. Appendix F: Data base plots for SSME tests 750-120 through 750-200

    Science.gov (United States)

    Coffin, T.

    1986-01-01

    A dynamic pressure data base and data base management system developed to characterize the Space Shuttle Main Engine (SSME) dynamic pressure environment is presented. The data base represents dynamic pressure measurements obtained during single engine hot firing tests of the SSME. Software is provided to permit statistical evaluation of selected measurements under specified operating conditions. An interpolation scheme is also included to estimate spectral trends with SSME power level.

  1. Turbine exhaust pressure measurements

    Energy Technology Data Exchange (ETDEWEB)

    Burns, J.M. [Stone & Webster Engineering Corp., Boston, MA (United States); Hernandez, E. [Community Energy Alternatives Inc., Ridgewood, NJ (United States)

    1996-05-01

    This paper discusses the dynamic operating environment in the turbine-condenser steam space and the two sensors, basket tips and guideplates, that have been approved by ASME test codes for measurement of the static pressure within that exhaust region. It defines the rigorous geometry and construction requirements of these sensors in order that they be acceptable for guarantee/acceptance testing. The paper also offers a practical alternative to the classical ASME PTC 6 (Turbine Test Code) basket tip design that is easier to fabricate in the typical utility machine shop. The alternative design makes it less expensive, much faster to construct, and facilitates the drainage of any accumulated condensate. Comparative field tests by PSE&G`s Research and Testing Laboratory conducted in 1995 at the 300 MW Mercer Generating Station, Unit 1 will be described which demonstrate the modified basket tip pressure measurements are statistically indistinguishable from those of the PTC 6 design. Noting that basket tip turbine exhaust static pressure sensors are recommended by all the major U.S. turbine manufacturers, the paper also presents the limited available history of the empirical basket tip and the lack of any documented calibration history related to the accuracy of the guideplate. Finally, based on the success of this one basket tip variation, the paper concludes that other even more suitable designs could be developed by further research.

  2. Phase Synchronization of Pressure-Flow Fluctuations: A measure of cerebral autoregulation dynamics

    CERN Document Server

    Chen, Z; Ivanov, P C; Novák, V; Stanley, H E

    2006-01-01

    We employ a synchronization method to investigate the relationship between the blood flow velocities (BFV) in the middle cerebral arteries (MCA) and beat-to-beat blood pressure (BP) recorded from a finger in healthy and post-stroke subjects during four different physiologic conditions: supine, head-up tilt, hyperventilation and CO$_2$ rebreathing in upright position. To evaluate whether instantaneous BP changes are synchronized with changes in the BFV, we compare dynamical patterns in the instantaneous phases of these signals, obtained from the Hilbert transform, as a function of time. We find that in post-stroke subjects the instantaneous phase increments of BP and BFV exhibit well pronounced patterns that remain stable in time for all four physiologic conditions, while in healthy subjects these patterns are different, less pronounced and more variable. Further, we show that the instantaneous phase increments of BP and BFV are cross-correlated even within a single heartbeat cycle. The maximum correlation str...

  3. Global surface pressure measurements of static and dynamic stall on a wind turbine airfoil at low Reynolds number

    Science.gov (United States)

    Disotell, Kevin J.; Nikoueeyan, Pourya; Naughton, Jonathan W.; Gregory, James W.

    2016-05-01

    Recognizing the need for global surface measurement techniques to characterize the time-varying, three-dimensional loading encountered on rotating wind turbine blades, fast-responding pressure-sensitive paint (PSP) has been evaluated for resolving unsteady aerodynamic effects in incompressible flow. Results of a study aimed at demonstrating the laser-based, single-shot PSP technique on a low Reynolds number wind turbine airfoil in static and dynamic stall are reported. PSP was applied to the suction side of a Delft DU97-W-300 airfoil (maximum thickness-to-chord ratio of 30 %) at a chord Reynolds number of 225,000 in the University of Wyoming open-return wind tunnel. Static and dynamic stall behaviors are presented using instantaneous and phase-averaged global pressure maps. In particular, a three-dimensional pressure topology driven by a stall cell pattern is detected near the maximum lift condition on the steady airfoil. Trends in the PSP-measured pressure topology on the steady airfoil were confirmed using surface oil visualization. The dynamic stall case was characterized by a sinusoidal pitching motion with mean angle of 15.7°, amplitude of 11.2°, and reduced frequency of 0.106 based on semichord. PSP images were acquired at selected phase positions, capturing the breakdown of nominally two-dimensional flow near lift stall, development of post-stall suction near the trailing edge, and a highly three-dimensional topology as the flow reattaches. Structural patterns in the surface pressure topologies are considered from the analysis of the individual PSP snapshots, enabled by a laser-based excitation system that achieves sufficient signal-to-noise ratio in the single-shot images. The PSP results are found to be in general agreement with observations about the steady and unsteady stall characteristics expected for the airfoil.

  4. Micro-Structured Sapphire Fiber Sensors for Simultaneous Measurements of High-T and Dynamic Gas Pressure in Harsh Environments

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Hai [Clemson Univ., SC (United States); Tsai, Hai-Lung [Missouri Univ. of Science and Technology, Rolla, MO (United States); Dong, Junhang [Univ. of Cincinnati, OH (United States)

    2014-09-30

    This is the final report for the program “Micro-Structured Sapphire Fiber Sensors for Simultaneous Measurements of High Temperature and Dynamic Gas Pressure in Harsh Environments”, funded by NETL, and performed by Missouri University of Science and Technology, Clemson University and University of Cincinnati from October 1, 2009 to September 30, 2014. Securing a sustainable energy economy by developing affordable and clean energy from coal and other fossil fuels is a central element to the mission of The U.S. Department of Energy’s (DOE) National Energy Technology Laboratory (NETL). To further this mission, NETL funds research and development of novel sensor technologies that can function under the extreme operating conditions often found in advanced power systems. The main objective of this research program is to conduct fundamental and applied research that will lead to successful development and demonstration of robust, multiplexed, microstructured silica and single-crystal sapphire fiber sensors to be deployed into the hot zones of advanced power and fuel systems for simultaneous measurements of high temperature and gas pressure. The specific objectives of this research program include: 1) Design, fabrication and demonstration of multiplexed, robust silica and sapphire fiber temperature and dynamic gas pressure sensors that can survive and maintain fully operational in high-temperature harsh environments. 2) Development and demonstration of a novel method to demodulate the multiplexed interferograms for simultaneous measurements of temperature and gas pressure in harsh environments. 3) Development and demonstration of novel sapphire fiber cladding and low numerical aperture (NA) excitation techniques to assure high signal integrity and sensor robustness.

  5. 测压管路动态特性实测技术研究%Study on measurement technology of dynamics characteristics of typical tubes for pressure measurements

    Institute of Scientific and Technical Information of China (English)

    余世策; 韩新刚; 冀晓华; 屠荣伟; 蒋建群

    2012-01-01

    利用声音振动发生原理研制了多功能声音振动发生装置,开发了测压管路动态特性的实测技术,并对风洞试验中典型测压管路的频响特性进行了实测.采用正弦压力波对不同的测压管路进行激励,采用多点联合扫描技术提高采样频率,得到完整的正弦波动曲线.实验研究结果表明,该实验技术可以得到高频的动态压力信号和准确的频响特性曲线,为误差修正提供了依据.%By using independently developed sound vibration generating device, the measurement technology of dynamics characteristics of typical tubes for pressure measurements was developed, and the frequency response characteristics of typical tubes for fluctuating wind pressure measurements were measured. By using principle of sound vibrations, a multi-function sound vibration generating device was developed. Different pipes were excited by sine pressure waves, multi-point scanning technology was used to improve the sampling frequency for getting full curves of sine waves. Experimental results show that the experimental technique developed can be ' used to obtain high-frequency dynamic pressure signals and accurate frequency response curve for providing a basis for the error correction.

  6. A low-power tool for measuring acceleration, pressure, and temperature (APT) with wide dynamic range and bandwidth

    Science.gov (United States)

    Heesemann, Martin; Davis, Earl E.; Paros, Jerome; Johnson, Greg; Meldrum, Robert; Scherwath, Martin; Mihaly, Steven

    2017-04-01

    We present a new tool that facilitates the study of inter-related geodetic, geodynamic, seismic, and oceanographic phenomena. It incorporates a temperature compensated tri-axial accelerometer developed by Quartz Seismic Sensors, Inc., a pressure sensor built by Paroscientific Inc., and a low-power, high-precision frequency counter developed by Bennest Enterprises Ltd. and built by RBR, Ltd. The sensors are housed in a 7 cm o.d. titanium pressure case designed for use to full ocean depths (withstands more than 20 km of water pressure). Sampling intervals are programmable from 0.08 s to 1 hr; standard memory can store up to 130 million samples; total power consumption is roughly 115 mW when operating continuously and proportionately lower when operating intermittently (e.g., 2 mW average at 1 sample per min). Serial and USB communications protocols allow a variety of autonomous and cable-connection options. Measurement precision of the order of 10-8 of full scale (e.g., pressure equivalent to 4000 m water depth, acceleration = +/- 3 g) allows observations of pressure and acceleration variations of 0.4 Pa and 0.3 μm s-2. Long-term variations in vertical acceleration are sensitive to displacement through the gravity gradient down to a level of roughly 2 cm, and variations in horizontal acceleration are sensitive to tilt down to a level of 0.03 μrad. With the large dynamic ranges, high sensitivities and broad bandwidth (6 Hz to DC), ground motion associated with microseisms, strong and weak seismic ground motion, tidal loading, and slow and rapid geodynamic deformation - all normally studied using disparate instruments - can be observed with a single tool. Installation in the marine environment is accomplished by pushing the tool roughly 1 m vertically below the seafloor with a submersible or remotely operated vehicle, with no profile remaining above the seafloor to cause current-induced noise. The weight of the tool is designed to match the sediment it displaces to

  7. [Measurement of arterial pressure].

    Science.gov (United States)

    Rorive, G

    1998-03-01

    The casual determination of blood pressure remains the basis of the diagnosis of arterial hypertension and the criteria for usefulness of drug therapy. The reference values usually in use concern determinations by the doctor in very well defined conditions, rest, size of the bladder, etc.... The poor reproductibility of the determinations made by the doctor in casual conditions has produced a large interest for new approaches: autodetermination by the patient at home, and ambulatory blood pressure determinations using automatic devices. These new approaches have their own reference values, specific indications and limitations.

  8. Dynamic pressures in porous media

    Science.gov (United States)

    Balcerak, Ernie

    2012-12-01

    Understanding the relationship between fluid pressures and water content (saturation) in soils or other porous media can be important in a wide range of practical areas, including oil recovery, infiltration and flooding during extreme weather events, and environmental remediation. The relationship between fluid pressures and saturation in porous media has been reported to be dynamic—to depend on the flow rate as saturation changes. However, previous studies designed to understand the dynamic component of this relationship have been highly contradictory. To learn more, Hou et al. conducted experiments to quantify the relationship between pressure and rate of saturation change using a small-volume system with highly characterized fluid selective microsensors. Their analyses corrected for two often-overlooked experimental artifacts: gas pressure gradients and sensor response rate. When the researchers applied these corrections, they found that the dependence of pressure on the rate of saturation change may be much less significant than previously thought. (Water Resources Research, doi:10.1029/2012WR012434, 2012)

  9. Blade Tip Pressure Measurements Using Pressure Sensitive Paint

    Science.gov (United States)

    Wong, Oliver D.; Watkins, Anthony Neal; Goodman, Kyle Z.; Crafton, James; Forlines, Alan; Goss, Larry; Gregory, James W.; Juliano, Thomas J.

    2012-01-01

    This paper discusses the application of pressure sensitive paint using laser-based excitation for measurement of the upper surface pressure distribution on the tips of rotor blades in hover and simulated forward flight. The testing was conducted in the Rotor Test Cell and the 14- by 22-ft Subsonic Tunnel at the NASA Langley Research Center on the General Rotor Model System (GRMS) test stand. The Mach-scaled rotor contained three chordwise rows of dynamic pressure transducers for comparison with PSP measurements. The rotor had an 11 ft 1 in. diameter, 5.45 in. main chord and a swept, tapered tip. Three thrust conditions were examined in hover, C(sub T) = 0.004, 0.006 and 0.008. In forward flight, an additional thrust condition, C(sub T) = 0.010 was also examined. All four thrust conditions in forward flight were conducted at an advance ratio of 0.35.

  10. High pressure rinsing parameters measurements

    Energy Technology Data Exchange (ETDEWEB)

    Cavaliere, E. [INFN Milano - LASA, Via F.lli Cervi 201, I-20090 Segrate (MI) (Italy); Fusetti, M. [INFN Milano - LASA, Via F.lli Cervi 201, I-20090 Segrate (MI) (Italy); Michelato, P. [INFN Milano - LASA, Via F.lli Cervi 201, I-20090 Segrate (MI) (Italy); Pagani, C. [INFN Milano - LASA, Via F.lli Cervi 201, I-20090 Segrate (MI) (Italy)]. E-mail: carlo.pagani@mi.infn.it; Pierini, P. [INFN Milano - LASA, Via F.lli Cervi 201, I-20090 Segrate (MI) (Italy); Paulon, R. [INFN Milano - LASA, Via F.lli Cervi 201, I-20090 Segrate (MI) (Italy); Sertore, D. [INFN Milano - LASA, Via F.lli Cervi 201, I-20090 Segrate (MI) (Italy)

    2006-07-15

    High pressure rinsing with ultra pure water jet is an essential step in the high field superconducting cavity production process. In this paper, we illustrate the experimental characterization of a HPR system, in terms of specific power and energy deposition on the cavity surfaces and on the damage threshold for niobium. These measurements are used to tentatively derive general rules for the optimization of the free process parameters (nozzle geometry, speeds and water pressure)

  11. Side abutment pressure distribution by field measurement

    Institute of Scientific and Technical Information of China (English)

    WANG Lian-guo; SONG Yang; HE Xing-hua; ZHANG Jian

    2008-01-01

    Given the 7123 working face in the Qidong Coal Mine of the Wanbei Mining Group, nine dynamic roof monitors were installed in the crossheading to measure the amount and velocity of roof convergence in different positions and at different times and three steel bored stress sensors were installed in the return airway to measure rock stress at depth. On the basis of this arrangement, the rule of change of the distribution of the side abutment pressure with the advance of the working face and movement of overlying strata was studied. The rule of change and the stability of rock stress at depth were measured. Secondly, the affected area and stability time of the side abutment pressure were also studied. The results show that: 1) During working, the face advanced distance was from 157 m to 99 m, the process was not effected by mining induced pressure. When the distance was 82 m, the position of peak stress was 5 m away from the coal wall. When the distance was 37 m, the position of peak stress away from the coal wall was about 15 m to 20 m and finally reached a steady state; 2) the time and the range of the peak of side rock pressure obtained from stress sensors were consistent with the results from the dynamic roof monitors; 3) the position of the peak pressure was 25 m away from the coal wall.

  12. Development of a Dynamic Biomechanical Model for Load Carriage: Phase 4, Part C3: Dynamic Assessment of Pressure Measurement Systems for Use in Human Load Carriage

    Science.gov (United States)

    2005-08-01

    technology by Tekscan , Inc., a capacitance-based technology by Novel, Inc., and XSENSOR® Technology Inc., and a piezoresistive technology by Vista...Vista Medical Inc), a pneumatic pressure sensor (Talley Pressure Monitor 3), and a Tekscan ‘seat’ 2056 sensor array. The abstract, however, neglected to...coefficients of variance for linearity ranging from 1.9%-9.9% using a Flexiforce system; a low pressure detection sensor by Tekscan Inc. As well

  13. Correcting for response lag in unsteady pressure measurements in water

    Energy Technology Data Exchange (ETDEWEB)

    Conger, R.N. [John Graham Associates, Seattle, WA (United States); Ramaprian, B.R. [Washington State Univ., Pullman, WA (United States). Dept. of Mechanical and Materials Engineering

    1993-12-01

    There is not much information available on the use of diaphragm-type pressure transducers for the measurements of unsteady pressures in liquids. A procedure for measuring the dynamic response of a pressure transducer in such applications and correcting for its inadequate response is discussed in this report. An example of the successful use of this method to determine unsteady surface pressures on a pitching airfoil in a water channel is presented.

  14. Sting Interference Effects as Determined by Measurements of Dynamic Stability Derivatives, Surface Pressure, and Base Pressure for Mach Numbers 2 through 8

    Science.gov (United States)

    1980-10-01

    essentially proportional to the heat flux imposed on the constantan foil. Gardon gage wall temperature measurements were made with iron-constantan...can- figura tion was influenced by the presence of the sting. 4. The free-flight drag data for the blunt configuration was 15 percent higher than

  15. Validation of computational fluid dynamics calculation using Rossendorf coolant mixing model flow measurements in primary loop of coolant in a pressurized water reactor model

    Energy Technology Data Exchange (ETDEWEB)

    Farkas, Istvan; Hutli, Ezddin; Faekas, Tatiana; Takacs, Antal; Guba, Attila; Toth, Ivan [Dept. of Thermohydraulics, Centre for Energy Research, Hungarian Academy of Sciences, Budapest (Hungary)

    2016-08-15

    The aim of this work is to simulate the thermohydraulic consequences of a main steam line break and to compare the obtained results with Rossendorf Coolant Mixing Model (ROCOM) 1.1 experimental results. The objective is to utilize data from steady-state mixing experiments and computational fluid dynamics (CFD) calculations to determine the flow distribution and the effect of thermal mixing phenomena in the primary loops for the improvement of normal operation conditions and structural integrity assessment of pressurized water reactors. The numerical model of ROCOM was developed using the FLUENT code. The positions of the inlet and outlet boundary conditions and the distribution of detailed velocity/turbulence parameters were determined by preliminary calculations. The temperature fields of transient calculation were averaged in time and compared with time-averaged experimental data. The perforated barrel under the core inlet homogenizes the flow, and therefore, a uniform temperature distribution is formed in the pressure vessel bottom. The calculated and measured values of lowest temperature were equal. The inlet temperature is an essential parameter for safety assessment. The calculation predicts precisely the experimental results at the core inlet central region. CFD results showed a good agreement (both qualitatively and quantitatively) with experimental results.

  16. Dynamics via measurability

    Directory of Open Access Journals (Sweden)

    2006-01-01

    Full Text Available Generators f for σ -algebras can be used to view the dynamics of an invertible measurable transformation T in terms of the range values of f ∘ T . Such generators are the norm rather than the exception. Related measurable and quantitative methods of estimating a function from the behavior of ergodic averages are also discussed.

  17. Noncontact Monitoring of Respiration by Dynamic Air-Pressure Sensor.

    Science.gov (United States)

    Takarada, Tohru; Asada, Tetsunosuke; Sumi, Yoshihisa; Higuchi, Yoshinori

    2015-01-01

    We have previously reported that a dynamic air-pressure sensor system allows respiratory status to be visually monitored for patients in minimally clothed condition. The dynamic air-pressure sensor measures vital information using changes in air pressure. To utilize this device in the field, we must clarify the influence of clothing conditions on measurement. The present study evaluated use of the dynamic air-pressure sensor system as a respiratory monitor that can reliably detect change in breathing patterns irrespective of clothing. Twelve healthy volunteers reclined on a dental chair positioned horizontally with the sensor pad for measuring air-pressure signals corresponding to respiration placed on the seat back of the dental chair in the central lumbar region. Respiratory measurements were taken under 2 conditions: (a) thinly clothed (subject lying directly on the sensor pad); and (b) thickly clothed (subject lying on the sensor pad covered with a pressure-reducing sheet). Air-pressure signals were recorded and time integration values for air pressure during each expiration were calculated. This information was compared with expiratory tidal volume measured simultaneously by a respirometer connected to the subject via face mask. The dynamic air-pressure sensor was able to receive the signal corresponding to respiration regardless of clothing conditions. A strong correlation was identified between expiratory tidal volume and time integration values for air pressure during each expiration for all subjects under both clothing conditions (0.840-0.988 for the thinly clothed condition and 0.867-0.992 for the thickly clothed condition). These results show that the dynamic air-pressure sensor is useful for monitoring respiratory physiology irrespective of clothing.

  18. Oxygen Escape from Venus During High Dynamic Pressure ICMEs

    Science.gov (United States)

    McEnulty, Tess; Luhmann, J. G.; Brain, D. A.; Fedorov, A.; Jian, L. K.; Russell, C. T.; Zhang, T.; Möstl, C.; Futaana, Y.; de Pater, I.

    2013-10-01

    Previous studies using data from Pioneer Venus suggested that oxygen ion escape flux may be enhanced by orders of magnitude during Interplanetary Coronal Mass Ejections. However, this large enhancement has been ambiguous in Venus Express ion data - with some analyses showing no flux enhancement or a small enhancement (within 2 times undisturbed cases). One possible explanation is that high escape flux may be due to high dynamic pressure in the solar wind, and the dynamic pressure has been lower during the VEX time period. So, we focus on ICMEs with the largest dynamic pressure and with VEX sampling of the escaping ions during the sheath of the ICMEs (during which the highest dynamic pressures in the solar wind occur). We will show the characteristics of these large events measured by VEX, and compare them to the largest ICMEs measured by PVO. We will then discuss estimates of the oxygen ion escape flux during these events.

  19. Theoretical research on aggregative dynamic pressure damper

    Institute of Scientific and Technical Information of China (English)

    HU Jun-hua; CAO Shu-ping; LUO Xiao-hui; NIU Zi-hua; XIN Ji-song

    2009-01-01

    To broaden the frequency width and increase the damping coefficient of a dynamic pressure damper, we designed an aggregative dynamic pressure damper (ADPD). Combined with the advantages of traditional dynamic pressure dampers (TDPD), ADPD can not only increase the damping coefficient in wide frequency range for valve control system, but also absorb partial pressure pulsations and impacts in the low and high frequency fields. Based on the theoretical research and the analysis compared with TDPD, we concluded that the ADPD was superior to the TDPD in the middle high frequency field, and the main parameters influencing the performance of the damper were the damping stiffness, orifice flow coefficient, pre-charge pressure, and the volume of the damper accumulator.

  20. A cross-sectional study to compare intraocular pressure measurement by sequential use of Goldman applanation tonometry, dynamic contour tonometry, ocular response analyzer, and Corvis ST

    Directory of Open Access Journals (Sweden)

    Sushma Tejwani

    2015-01-01

    Full Text Available Objective: To study the correlation and effect of sequential measurement of intraocular pressure (IOP with Goldmann applanation tonometer (GAT, ocular response analyzer (ORA, dynamic contour tonometer (DCT, and Corvis ST. Setting and Design: Observational cross-sectional series from the comprehensive clinic of a tertiary eye care center seen during December 2012. Methods: One hundred and twenty-five study eyes of 125 patients with normal IOP and biomechanical properties underwent IOP measurement on GAT, DCT, ORA, and Corvis ST; in four different sequences. Patients with high refractive errors, recent surgeries, glaucoma, and corneal disorders were excluded so as to rule out patients with evident altered corneal biomechanics. Statistical Analysis: Linear regression and Bland-Altman using MedCalc software. Results: Multivariate analysis of variance with repeated measures showed no influence of sequence of device use on IOP (P = 0.85. Linear regression r 2 between GAT and Corvis ST, Corvis ST and Goldmann-correlated IOP (IOPg, and DCT and Corvis ST were 0.37 (P = 0.675, 0.63 (P = 0.607, and 0.19 (P = 0.708, respectively. The Bland-Altman agreement of Corvis ST with GAT, corneal compensated IOP, and IOPg was 2 mmHg (−5.0 to + 10.3, −0.5 mmHg (−8.1 to 7.1, and 0.5 mmHg (−6.2 to 7.1, respectively. Intraclass correlation coefficient for repeatability ranged from 0.81 to 0.96. Conclusions: Correlation between Corvis ST and ORA was found to be good and not so with GAT. However, agreement between the devices was statistically insignificant, and no influence of sequence was observed.

  1. Pressures Detector Calibration and Measurement

    CERN Document Server

    AUTHOR|(CDS)2156315

    2016-01-01

    This is report of my first and second projects (of 3) in NA61. I did data taking and analysis in order to do calibration of pressure detectors and verified it. I analyzed the data by ROOT software using the C ++ programming language. The first part of my project was determination of calibration factor of pressure sensors. Based on that result, I examined the relation between pressure drop, gas flow rate of in paper filter and its diameter.

  2. Effect of accelerated corneal crosslinking combined with transepithelial photorefractive keratectomy on dynamic corneal response parameters and biomechanically corrected intraocular pressure measured with a dynamic Scheimpflug analyzer in healthy myopic patients.

    Science.gov (United States)

    Lee, Hun; Roberts, Cynthia J; Ambrósio, Renato; Elsheikh, Ahmed; Kang, David Sung Yong; Kim, Tae-Im

    2017-07-01

    To evaluate the effect of accelerated corneal crosslinking (CXL) combined with transepithelial photorefractive keratectomy (PRK) on changes in new dynamic corneal response parameters and the biomechanically corrected intraocular pressure (IOP) measured using a dynamic Scheimpflug analyzer (Corvis ST). Yonsei University College of Medicine and Eyereum Eye Clinic, Seoul, South Korea. Retrospective case series. Medical records of eyes of healthy myopic patients having transepithelial PRK or transepithelial PRK with CXL were examined. Main outcome variables were the biomechanically corrected IOP and new dynamic corneal response parameters including the deformation amplitude ratio at 1.0 mm (DAR1) and at 2.0 mm (DAR2), stiffness at first applanation and at highest concavity, and the integrated inverse radius preoperatively and 6 months postoperatively. The study comprised 69 eyes (69 patients); 35 had transepithelial PRK and 34, transepithelial PRK with CXL. The DAR1, DAR2, and integrated inverse radius significantly increased, while stiffness at first applanation and at highest concavity decreased postoperatively in both groups. Changes in the DAR2 and integrated inverse radius in the transepithelial PRK group were significantly larger than in the transepithelial PRK with CXL group without and with analysis of covariance with the spherical equivalent change or corneal thickness change as a covariate. No significant differences in the biomechanically corrected IOP occurred preoperatively or postoperatively in either group. Results indicate that prophylactic CXL combined with transepithelial PRK has a role in reducing the change in corneal biomechanical properties. The dynamic Scheimpflug analyzer showed stable biomechanically corrected IOP measurements preoperatively and postoperatively. Copyright © 2017 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  3. Dynamic interface pressure distributions of two transtibial prosthetic socket concepts.

    Science.gov (United States)

    Dumbleton, Tim; Buis, Arjan W P; McFadyen, Angus; McHugh, Brendan F; McKay, Geoff; Murray, Kevin D; Sexton, Sandra

    2009-01-01

    In this study, we investigated and compared the dynamic interface pressure distribution of hands-off and hands-on transtibial prosthetic systems by means of pressure mapping. Of the 48 established unilateral amputees recruited, half (n = 24) had been wearing pressure-cast prostheses (IceCast Compact) and the other half (n = 24) had been wearing hand-cast sockets of the patellar tendon bearing design. We measured the dynamic pressure profile of more than 90% of the area within each prosthetic socket by means of four Tekscan F-Scan socket transducer arrays. We compared the interface pressure between socket concepts. We found that the distribution of dynamic pressure at the limb-socket interface was similar for the two intervention (socket prescription) groups. However, a significant difference was found in the magnitude of the interface pressure between the two socket concepts; the interface pressures recorded in the hands-off sockets were higher than those seen in the hands-on concept. Despite the differences in interface pressure, the level of satisfaction with the sockets was similar between subject groups. The sockets instrumented for this study had been in daily use for at least 6 months, with no residual-limb health problems.

  4. Spatial resolution in plantar pressure measurement revisited.

    Science.gov (United States)

    Pataky, Todd C

    2012-08-09

    Plantar pressures are typically measured using sensors of finite area, so the accuracy with which one can measure true maximum pressure is dependent on sensor size. Measurement accuracy has been modeled previously for one patient's metatarsals (Lord, 1997), but has not been modeled either for general subjects or for other parts of the foot. The purposes of this study were (i) to determine whether Lord's (1997) model is also valid for heel and hallux pressures, and (ii) to examine how sensor size relates to measurement accuracy in the context of four factors common to many measurement settings: pressure pulse size, foot positioning, pressure change quantification, and gross pressure redistribution. Lord's (1997) model was first generalized and was then validated using 10 healthy walking subjects, with relatively low RMSE values on the order of 20 kPa. Next, postural data were used to show that gross pressure redistributions can be accurately quantified (ppressure measurement tasks.

  5. Vapor pressure measured with inflatable plastic bag

    Science.gov (United States)

    1965-01-01

    Deflated plastic bag in a vacuum chamber measures initial low vapor pressures of materials. The bag captures the test sample vapors and visual observation of the vapor-inflated bag under increasing external pressures yields pertinent data.

  6. A microwave pressure sounder. [for remote measurement of atmospheric pressure

    Science.gov (United States)

    Peckham, G. E.; Flower, D. A.

    1981-01-01

    A technique for the remote measurement of atmospheric surface pressure will be described. Such measurements could be made from a satellite in polar orbit and would cover many areas for which conventional meteorological data are not available. An active microwave instrument is used to measure the strength of return echoes from the ocean surface at a number of frequencies near the 60 GHz oxygen absorption band. Factors which affect the accuracy with which surface pressure can be deduced from these measurements will be discussed and an instrument designed to test the method by making measurements from an aircraft will be described.

  7. Foot Plantar Pressure Measurement System: A Review

    Directory of Open Access Journals (Sweden)

    Yufridin Wahab

    2012-07-01

    Full Text Available Foot plantar pressure is the pressure field that acts between the foot and the support surface during everyday locomotor activities. Information derived from such pressure measures is important in gait and posture research for diagnosing lower limb problems, footwear design, sport biomechanics, injury prevention and other applications. This paper reviews foot plantar sensors characteristics as reported in the literature in addition to foot plantar pressure measurement systems applied to a variety of research problems. Strengths and limitations of current systems are discussed and a wireless foot plantar pressure system is proposed suitable for measuring high pressure distributions under the foot with high accuracy and reliability. The novel system is based on highly linear pressure sensors with no hysteresis.

  8. Optical Pressure Measurements of Explosions

    Science.gov (United States)

    2013-09-01

    Explosive Shocks in Air, 2nd ed.; Springer-Verlag: Berlin , Germany, 1985. 7. Anderson, J. D. Hypersonic and High Temperature Gas Dynamics, 2nd Ed...PDF) RDRL CIO LA T LANDFRIED RDRL WML M ZOLTOSKI RDRL WML A F DE LUCIA W OBERLE RDRL WML B J GOTTFRIED J CIEZAK

  9. On output measurements via radiation pressure

    DEFF Research Database (Denmark)

    Leeman, S.; Healey, A.J.; Forsberg, F.;

    1990-01-01

    It is shown, by simple physical argument, that measurements of intensity with a radiation pressure balance should not agree with those based on calorimetric techniques. The conclusion is ultimately a consequence of the circumstance that radiation pressure measurements relate to wave momentum, whi...

  10. Dynamic active earth pressure on retaining structures

    Indian Academy of Sciences (India)

    Deepankar Choudhury; Santiram Chatterjee

    2006-12-01

    Earth-retaining structures constitute an important topic of research in civil engineering, more so under earthquake conditions. For the analysis and design of retaining walls in earthquake-prone zones, accurate estimation of dynamic earth pressures is very important. Conventional methods either use pseudo-static approaches of analysis even for dynamic cases or a simple single-degree of freedom model for the retaining wall–soil system. In this paper, a simplified two-degree of freedom mass–spring–dashpot (2-DOF) dynamic model has been proposed to estimate the active earth pressure at the back of the retaining walls for translation modes of wall movement under seismic conditions. The horizontal zone of influence on dynamic earth force on the wall is estimated. Results in terms of displacement, velocity and acceleration-time history are presented for some typical cases, which show the final movement of the wall in terms of wall height, which is required for the design. The non-dimensional design chart proposed in the present study can be used to compute the total dynamic earth force on the wall under different input ground motion and backfill conditions. Finally, the results obtained have been compared with those of the available Scott model and the merits of the present results have been discussed.

  11. Micro packaged MEMS pressure sensor for intracranial pressure measurement

    Science.gov (United States)

    Xiong, Liu; Yan, Yao; Jiahao, Ma; Yanhang, Zhang; Qian, Wang; Zhaohua, Zhang; Tianling, Ren

    2015-06-01

    This paper presents a micro packaged MEMS pressure sensor for intracranial pressure measurement which belongs to BioMEMS. It can be used in lumbar puncture surgery to measure intracranial pressure. Miniaturization is key for lumbar puncture surgery because the sensor must be small enough to allow it be placed in the reagent chamber of the lumbar puncture needle. The size of the sensor is decided by the size of the sensor chip and package. Our sensor chip is based on silicon piezoresistive effect and the size is 400 × 400 μm2. It is much smaller than the reported polymer intracranial pressure sensors such as liquid crystal polymer sensors. In terms of package, the traditional dual in-line package obviously could not match the size need, the minimal size of recently reported MEMS-based intracranial pressure sensors after packaging is 10 × 10 mm2. In this work, we are the first to introduce a quad flat no-lead package as the package form of piezoresistive intracranial pressure sensors, the whole size of the sensor is minimized to only 3 × 3 mm2. Considering the liquid measurement environment, the sensor is gummed and waterproof performance is tested; the sensitivity of the sensor is 0.9 × 10-2 mV/kPa. Project supported by the National Natural Science Foundation of China (Nos. 61025021, 61434001), and the ‘Thousands Talents’ Program for Pioneer Researchers and Its Innovation Team, China.

  12. Dynamic temperature measurements with embedded optical sensors.

    Energy Technology Data Exchange (ETDEWEB)

    Dolan, Daniel H.,; Seagle, Christopher T; Ao, Tommy

    2013-10-01

    This report summarizes LDRD project number 151365, \\Dynamic Temperature Measurements with Embedded Optical Sensors". The purpose of this project was to develop an optical sensor capable of detecting modest temperature states (<1000 K) with nanosecond time resolution, a recurring diagnostic need in dynamic compression experiments at the Sandia Z machine. Gold sensors were selected because the visible re ectance spectrum of gold varies strongly with temperature. A variety of static and dynamic measurements were performed to assess re ectance changes at di erent temperatures and pressures. Using a minimal optical model for gold, a plausible connection between static calibrations and dynamic measurements was found. With re nements to the model and diagnostic upgrades, embedded gold sensors seem capable of detecting minor (<50 K) temperature changes under dynamic compression.

  13. Measuring Viscosities of Gases at Atmospheric Pressure

    Science.gov (United States)

    Singh, Jag J.; Mall, Gerald H.; Hoshang, Chegini

    1987-01-01

    Variant of general capillary method for measuring viscosities of unknown gases based on use of thermal mass-flowmeter section for direct measurement of pressure drops. In technique, flowmeter serves dual role, providing data for determining volume flow rates and serving as well-characterized capillary-tube section for measurement of differential pressures across it. New method simple, sensitive, and adaptable for absolute or relative viscosity measurements of low-pressure gases. Suited for very complex hydrocarbon mixtures where limitations of classical theory and compositional errors make theoretical calculations less reliable.

  14. Beam Loss Diagnostics Based on Pressure Measurements

    CERN Document Server

    Weinrich, U

    2003-01-01

    The GSI is operating a heavy ion synchrotron, which is currently undergoing an upgrade towards higher beam intensities. It was discovered that beam losses induce a significant pressure increase in the vacuum system. In order to detect the time constants of the pressure increase and decrease, fast total pressure measurements were put into operation. With the recently installed partial pressure diagnostics it is also possible to follow up which types of molecules are released. The presentation will focus on the different techniques applied as well as on some measurement results. The potential and difficulties of this diagnostic tool will also be discussed.

  15. Finger and Palm Dynamic Pressure Monitoring for Basketball Shooting

    Directory of Open Access Journals (Sweden)

    Chiao-Fang Hung

    2017-01-01

    Full Text Available This study verified general inferences on the finger and palm pressure distribution of a basketball player in the moment before that player shoots a basketball through a scientific qualitative testing method. We mounted the sensor on the hands of college basketball players and monitored the dynamic pressure of each player’s hand while the player threw a basketball. The dynamic pressure distribution of the fingers and palm of a basketball player throwing a ball can be verified. According to the experimental results, college basketball players typically use the index finger to control the direction and power of force in the moment before shooting a basketball. This study successfully used a scientific qualitative test method to monitor the dynamic pressure of the fingers and palms of basketball players and verified the general inference that a typical basketball player mainly uses the index finger to control the direction and power of force in the moment before throwing a ball. In the future, this study, measuring the dynamic pressure distribution of the fingers and palm, can be applied to simulate hand manipulation in many biomedical and robotic applications.

  16. Error Propagation Dynamics of PIV-based Pressure Field Calculations: How well does the pressure Poisson solver perform inherently?

    Science.gov (United States)

    Pan, Zhao; Whitehead, Jared; Thomson, Scott; Truscott, Tadd

    2016-08-01

    Obtaining pressure field data from particle image velocimetry (PIV) is an attractive technique in fluid dynamics due to its noninvasive nature. The application of this technique generally involves integrating the pressure gradient or solving the pressure Poisson equation using a velocity field measured with PIV. However, very little research has been done to investigate the dynamics of error propagation from PIV-based velocity measurements to the pressure field calculation. Rather than measure the error through experiment, we investigate the dynamics of the error propagation by examining the Poisson equation directly. We analytically quantify the error bound in the pressure field, and are able to illustrate the mathematical roots of why and how the Poisson equation based pressure calculation propagates error from the PIV data. The results show that the error depends on the shape and type of boundary conditions, the dimensions of the flow domain, and the flow type.

  17. Error Propagation Dynamics of PIV-based Pressure Field Calculations: How well does the pressure Poisson solver perform inherently?

    CERN Document Server

    Pan, Zhao; Thomson, Scott; Truscott, Tadd

    2016-01-01

    Obtaining pressure field data from particle image velocimetry (PIV) is an attractive technique in fluid dynamics due to its noninvasive nature. The application of this technique generally involves integrating the pressure gradient or solving the pressure Poisson equation using a velocity field measured with PIV. However, very little research has been done to investigate the dynamics of error propagation from PIV-based velocity measurements to the pressure field calculation. Rather than measure the error through experiment, we investigate the dynamics of the error propagation by examining the Poisson equation directly. We analytically quantify the error bound in the pressure field, and are able to illustrate the mathematical roots of why and how the Poisson equation based pressure calculation propagates error from the PIV data. The results show that the error depends on the shape and type of boundary conditions, the dimensions of the flow domain, and the flow type.

  18. Error propagation dynamics of PIV-based pressure field calculations: How well does the pressure Poisson solver perform inherently?

    Science.gov (United States)

    Pan, Zhao; Whitehead, Jared; Thomson, Scott; Truscott, Tadd

    2016-08-01

    Obtaining pressure field data from particle image velocimetry (PIV) is an attractive technique in fluid dynamics due to its noninvasive nature. The application of this technique generally involves integrating the pressure gradient or solving the pressure Poisson equation using a velocity field measured with PIV. However, very little research has been done to investigate the dynamics of error propagation from PIV-based velocity measurements to the pressure field calculation. Rather than measure the error through experiment, we investigate the dynamics of the error propagation by examining the Poisson equation directly. We analytically quantify the error bound in the pressure field, and are able to illustrate the mathematical roots of why and how the Poisson equation based pressure calculation propagates error from the PIV data. The results show that the error depends on the shape and type of boundary conditions, the dimensions of the flow domain, and the flow type.

  19. Water dynamics and retrogradation of ultrahigh pressurized wheat starch.

    Science.gov (United States)

    Doona, Christopher J; Feeherry, Florence E; Baik, Moo-Yeol

    2006-09-06

    The water dynamics and retrogradation kinetics behavior of gelatinized wheat starch by either ultrahigh pressure (UHP) processing or heat are investigated. Wheat starch completely gelatinized in the condition of 90, 000 psi at 25 degrees C for 30 min (pressurized gel) or 100 degrees C for 30 min (heated gel). The physical properties of the wheat starches were characterized in terms of proton relaxation times (T2 times) measured using time-domain nuclear magnetic resonance spectroscopy and evaluated using commercially available continuous distribution modeling software. Different T2 distributions in both micro- and millisecond ranges between pressurized and heated wheat starch gels suggest distinctively different water dynamics between pressurized and heated wheat starch gels. Smaller water self-diffusion coefficients were observed for pressurized wheat starch gels and are indicative of more restricted translational proton mobility than is observed with heated wheat starch gels. The physical characteristics associated with changes taking place during retrogradation were evaluated using melting curves obtained with differential scanning calorimetry. Less retrogradation was observed in pressurized wheat starch, and it may be related to a smaller quantity of freezable water in pressurized wheat starch. Starches comprise a major constituent of many foods proposed for commercial potential using UHP, and the present results furnish insight into the effect of UHP on starch gelatinization and the mechanism of retrogradation during storage.

  20. Ambulatory blood pressure measuring devices.

    Science.gov (United States)

    Krönig, B

    1996-01-01

    During the last 6 years ABPM has become a widely used method in the diagnosis and treatment of hypertensive patients as well as in correlating the disease to prognosis. Up to January 1995, the international market offered 43 devices from 31 manufacturers. In Germany there are 18 devices available on the market from 10 different manufactures. Mainly, two different techniques are applied, ausculation and oscillometry, each having some advantages and disadvantages: The oscillometric technique may be preferable in patients with hyperkinetic circulation (e.g., pregnancy), with ausculatory gap and when surrounding noises are interfering, whereas the auscultatory technique, being the original method, has some advantages in patients with dysrhythmias and atrial fibrillation, as well as in dynamic (bicycle) exercise. The auscultatory method may be optimized by using ECG-, respectively oscillometric gating. The future development, which has already been realized in seven international recorders, offers the opportunity of either using auscultatory and/or oscillometric techniques during the same recording. To estimate the "true" sleeping interval more precisely a "day-night-button" at the recorder side is helpful. Furthermore, an uniform computer printout of the mean values of day- and night-time intervals, together with the widely approved limits of normotension should be achieved; last, but not least, an important factor for the widespread use of ABPM in general practice, as well as in the hospital, will be the prices of the recorders. Which have been reduced to about DM 3000-6000 in Germany (January 1996).

  1. Material deformation dynamics at ultrahigh pressures and strain rates

    Science.gov (United States)

    Remington, B. A.; Park, H. S.; Maddox, B. R.; May, M. J.; Pollaine, S. M.; Prisbrey, S. T.; Rudd, R. E.; Hawreliak, J. A.; Perry, T. S.; Comley, A. J.; Wark, J. S.; Meyers, M. A.

    2010-11-01

    Solid-state dynamics experiments at extreme pressures, up to 10 Mbar, and strain rates (1.e6 -1.e8 1/s) are being developed for the NIF laser. The experimental methods are being developed on the Omega laser facility. VISAR measurements establish the ramped, high-pressure conditions. Recovery experiments offer a look at the residual microstructure. Dynamic diffraction measurements allow phase, shear stress (strength), and possibly twin volume fraction and dislocation density to be inferred. Constitutive models for material strength at these conditions by comparing 2D simulations with experiments measuring the Rayleigh-Taylor instability evolution in solid-state samples of vanadium and tantalum. The material deformation likely falls into the phonon drag regime. We estimate of the (microscopic) phonon drag coefficient, by relating to the (macroscopic) effective lattice viscosity.

  2. The high pressure structure and equation of state of 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) up to 20 GPa: X-ray diffraction measurements and first principles molecular dynamics simulations

    Energy Technology Data Exchange (ETDEWEB)

    Stavrou, Elissaios, E-mail: stavrou1@llnl.gov; Riad Manaa, M., E-mail: manaa1@llnl.gov; Zaug, Joseph M.; Kuo, I-Feng W.; Pagoria, Philip F.; Crowhurst, Jonathan C.; Armstrong, Michael R. [Lawrence Livermore National Laboratory, Physical and Life Sciences Directorate, P.O. Box 808 L-350, Livermore, California 94550 (United States); Kalkan, Bora [Advanced Light Source, Lawrence Berkeley Laboratory, Berkeley, California 94720 (United States); Advanced Materials Research Laboratory, Department of Physics Engineering, Hacettepe University 06800, Beytepe, Ankara (Turkey)

    2015-10-14

    Recent theoretical studies of 2,6-diamino-3,5-dinitropyrazine-1-oxide (C{sub 4}H{sub 4}N{sub 6}O{sub 5} Lawrence Livermore Molecule No. 105, LLM-105) report unreacted high pressure equations of state that include several structural phase transitions, between 8 and 50 GPa, while one published experimental study reports equation of state (EOS) data up to a pressure of 6 GPa with no observed transition. Here we report the results of a synchrotron-based X-ray diffraction study and also ambient temperature isobaric-isothermal atomistic molecular dynamics simulations of LLM-105 up to 20 GPa. We find that the ambient pressure phase remains stable up to 20 GPa; there is no indication of a pressure induced phase transition. We do find a prominent decrease in b-axis compressibility starting at approximately 13 GPa and attribute the stiffening to a critical length where inter-sheet distance becomes similar to the intermolecular distance within individual sheets. The ambient temperature isothermal equation of state was determined through refinements of measured X-ray diffraction patterns. The pressure-volume data were fit using various EOS models to yield bulk moduli with corresponding pressure derivatives. We find very good agreement between the experimental and theoretically derived EOS.

  3. The high pressure structure and equation of state of 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) up to 20 GPa: X-ray diffraction measurements and first principles molecular dynamics simulations.

    Science.gov (United States)

    Stavrou, Elissaios; Riad Manaa, M; Zaug, Joseph M; Kuo, I-Feng W; Pagoria, Philip F; Kalkan, Bora; Crowhurst, Jonathan C; Armstrong, Michael R

    2015-10-14

    Recent theoretical studies of 2,6-diamino-3,5-dinitropyrazine-1-oxide (C4H4N6O5 Lawrence Livermore Molecule No. 105, LLM-105) report unreacted high pressure equations of state that include several structural phase transitions, between 8 and 50 GPa, while one published experimental study reports equation of state (EOS) data up to a pressure of 6 GPa with no observed transition. Here we report the results of a synchrotron-based X-ray diffraction study and also ambient temperature isobaric-isothermal atomistic molecular dynamics simulations of LLM-105 up to 20 GPa. We find that the ambient pressure phase remains stable up to 20 GPa; there is no indication of a pressure induced phase transition. We do find a prominent decrease in b-axis compressibility starting at approximately 13 GPa and attribute the stiffening to a critical length where inter-sheet distance becomes similar to the intermolecular distance within individual sheets. The ambient temperature isothermal equation of state was determined through refinements of measured X-ray diffraction patterns. The pressure-volume data were fit using various EOS models to yield bulk moduli with corresponding pressure derivatives. We find very good agreement between the experimental and theoretically derived EOS.

  4. Measuring Dynamic Transfer Functions of Cavitating Pumps

    Science.gov (United States)

    Baun, Daniel

    2007-01-01

    A water-flow test facility has been built to enable measurement of dynamic transfer functions (DTFs) of cavitating pumps and of inducers in such pumps. Originally, the facility was intended for use in an investigation of the effects of cavitation in a rocket-engine low-pressure oxygen turbopump. The facility can also be used to measure DTFs of cavitating pumps in general

  5. Centrifugal pump inlet pressure site affects measurement.

    Science.gov (United States)

    Augustin, Simon; Horton, Alison; Butt, Warwick; Bennett, Martin; Horton, Stephen

    2010-09-01

    During extracorporeal life support (ECLS), blood is exposed to a myriad of unphysiological factors that can affect outcome. One aspect of this is the sub-atmospheric pressure generated by the ECLS pump and imparted to blood elements along the pump inlet line. This pressure can be measured on the inlet line close to the pump head by adding a connector, or at the venous cannula connection site. We compared the two measurement sites located at both points; between the venous cannula-inlet tubing and inlet tubing-pump, with a range of cannulae and flows. We also investigated the effects on inlet pressure from pump afterload and increasing inlet tubing length.

  6. Measuring Pressure Drop Under Non Ideal Conditions

    Directory of Open Access Journals (Sweden)

    Austin M

    2014-12-01

    Full Text Available The method of measurement of the pressure drop (PD of cigarette filter rods and the draw resistance of cigarettes is defined in ISO 6565-2002 (1. This standard defines the calibration and use of a transfer standard to calibrate the measuring instrument and also defines the measurement procedure for cigarette and filter samples. The procedure described in the standard assumes that the measurement conditions are constant and that the sample is in equilibrium with the measurement environment.

  7. Dynamic Mode Decomposition of Fast Pressure Sensitive Paint Data

    Directory of Open Access Journals (Sweden)

    Mohd Y. Ali

    2016-06-01

    Full Text Available Fast-response pressure sensitive paint (PSP is used in this work to measure and analyze the acoustic pressure field in a rectangular cavity. The high spatial resolution and fast frequency response of PSP effectively captures the spatial and temporal detail of surface pressure resulting in the acoustic pressure field. In this work, a high-speed camera is used to generate a continuous time record of the acoustic pressure fluctuations with PSP. Since the level of the acoustic pressure is near the resolution limit of the sensor system, advanced analysis techniques are used to extract the spatial modes of the pressure field. Both dynamic mode decomposition (DMD and proper orthogonal decomposition (POD are compared with phase averaging for data analysis. While all three techniques effectively extract the pressure field and reduce the impact of sensor noise, DMD and POD are more robust techniques that can be applied to aperiodic or multi-frequency signals. Furthermore, DMD is better than POD at suppressing noise in particular regions of the spectrum and at effectively separating spectral energy when multiple acoustic excitation frequencies are present.

  8. Pressure measurements in magnetic-fusion devices

    Energy Technology Data Exchange (ETDEWEB)

    Dylla, H.F.

    1981-11-01

    Accurate pressure measurements are important in magnetic fusion devices for: (1) plasma diagnostic measurements of particle balance and ion temperature; (2) discharge cleaning optimization; (3) vacuum system performance; and (4) tritium accountability. This paper reviews the application, required accuracy, and suitable instrumentation for these measurements. Demonstrated uses of ionization-type and capacitance-diaphragm gauges for various pressure and gas-flow measurements in tokamaks are presented, with specific reference to the effects of magnetic fields on gauge performance and the problems associated with gauge calibration.

  9. Pancreas tumor interstitial pressure catheter measurement

    Science.gov (United States)

    Nieskoski, Michael D.; Gunn, Jason; Marra, Kayla; Trembly, B. Stuart; Pogue, Brian W.

    2016-03-01

    This paper highlights the methodology in measuring interstitial pressure in pancreatic adenocarcinoma tumors. A Millar Mikrotip pressure catheter (SPR-671) was used in this study and a system was built to amplify and filter the output signal for data collection. The Millar pressure catheter was calibrated prior to each experiment in a water column at 37°C, range of 0 to 60 inH2O (112 mmHg), resulting in a calibration factor of 33 mV / 1 inH2O. The interstitial pressures measured in two orthotopically grown pancreatic adenocarcinoma tumor were 57 mmHg and 48 mmHg, respectively. Verteporfin uptake into the pancreatic adenocarcinoma tumor was measured using a probe-based experimental dosimeter.

  10. New pressure cell for ultrasonic measurements

    Science.gov (United States)

    Kepa, Michal; Huxley, Andrew; Kamenev, Konstantin

    2013-06-01

    Ultrasonic interferometry at high pressure remains a technical challenge as the small sample space requires the application of very high-frequency ultrasound. Here we present the design of a new cell developed specifically for ultrasonic measurements of single crystals at low temperatures (2K) and high pressures (5GPa). The design allows greater sample space (compared to a conventional diamond anvil cell) and simultaneous measurement of ultrasonic attenuation and velocities. Coupling the fine transducers to spherical sapphire anvils reduces background and enables different polarizations of the ultrasonic wave to be measured at the same pressure and temperature conditions. The results are used to deduce the elastic, electronic and magnetic properties of a crystal. The finite element analysis of the cell together with the pressure calibration curves and test data taken on UGe2 are presented.

  11. Working meeting on blood pressure measurement: suggestions for measuring blood pressure to use in populations surveys.

    Science.gov (United States)

    2003-11-01

    As part of the Pan American Hypertension Initiative (PAHI), the Pan American Health Organization and the National Heart, Lung, and Blood Institute of the National Institutes of Health of the United States of America conducted a working meeting to discuss blood pressure (BP) measurement methods used in various hypertension prevalence surveys and clinical trials, with the objective of developing a BP measurement protocol for use in hypertension prevalence surveys in the Americas. No such common protocol has existed in the Americas, so it has been difficult to compare hypertension prevention and intervention strategies. This piece describes a proposed standard method for measuring blood pressure for use in population surveys in the Region of the Americas. The piece covers: considerations for developing a common blood pressure measurement protocol, critical issues in measuring blood pressure in national surveys, minimum procedures for blood pressure measurement during surveillance, and quality assessment of blood pressure.

  12. Pressure Gradient Estimation Based on Ultrasonic Blood Flow Measurement

    Science.gov (United States)

    Nitta, Naotaka; Homma, Kazuhiro; Shiina, Tsuyoshi

    2006-05-01

    Mechanical load to the blood vessel wall, such as shear stress and pressure, which occurs in blood flow dynamics, contribute greatly to plaque rupture in arteriosclerosis and to biochemical activation of endothelial cells. Therefore, noninvasive estimations of these mechanical loads are able to provide useful information for the prevention of vascular diseases. Although the pressure is the dominant component of mechanical load, for practical purposes, the pressure gradient is also often important. So far, we have investigated the estimation of the kinematic viscosity coefficient using a combination of the Navier-Stokes equations and ultrasonic velocity measurement. In this paper, a method for pressure gradient estimation using the estimated kinematic viscosity coefficient is proposed. The validity of the proposed method was investigated on the basis of the analysis with the data obtained by computer simulation and a flow phantom experiment. These results revealed that the proposed method can provide a valid estimation of the pressure gradient.

  13. Material dynamics under extreme conditions of pressure and strain rate

    Energy Technology Data Exchange (ETDEWEB)

    Remington, B A; Allen, P; Bringa, E; Hawreliak, J; Ho, D; Lorenz, K T; Lorenzana, H; Meyers, M A; Pollaine, S W; Rosolankova, K; Sadik, B; Schneider, M S; Swift, D; Wark, J; Yaakobi, B

    2005-09-06

    Solid state experiments at extreme pressures (10-100 GPa) and strain rates ({approx}10{sup 6}-10{sup 8}s{sup -1}) are being developed on high-energy laser facilities, and offer the possibility for exploring new regimes of materials science. These extreme solid-state conditions can be accessed with either shock loading or with a quasi-isentropic ramped pressure drive. Velocity interferometer measurements establish the high pressure conditions. Constitutive models for solid-state strength under these conditions are tested by comparing 2D continuum simulations with experiments measuring perturbation growth due to the Rayleigh-Taylor instability in solid-state samples. Lattice compression, phase, and temperature are deduced from extended x-ray absorption fine structure (EXAFS) measurements, from which the shock-induced {alpha}-{omega} phase transition in Ti and the {alpha}-{var_epsilon} phase transition in Fe are inferred to occur on sub-nanosec time scales. Time resolved lattice response and phase can also be measured with dynamic x-ray diffraction measurements, where the elastic-plastic (1D-3D) lattice relaxation in shocked Cu is shown to occur promptly (< 1 ns). Subsequent large-scale molecular dynamics (MD) simulations elucidate the microscopic dynamics that underlie the 3D lattice relaxation. Deformation mechanisms are identified by examining the residual microstructure in recovered samples. The slip-twinning threshold in single-crystal Cu shocked along the [001] direction is shown to occur at shock strengths of {approx}20 GPa, whereas the corresponding transition for Cu shocked along the [134] direction occurs at higher shock strengths. This slip-twinning threshold also depends on the stacking fault energy (SFE), being lower for low SFE materials. Designs have been developed for achieving much higher pressures, P > 1000 GPa, in the solid state on the National Ignition Facility (NIF) laser.

  14. In-shoe plantar pressure measurement and analysis system based on fabric pressure sensing array.

    Science.gov (United States)

    Shu, Lin; Hua, Tao; Wang, Yangyong; Qiao Li, Qiao; Feng, David Dagan; Tao, Xiaoming

    2010-05-01

    Spatial and temporal plantar pressure distributions are important and useful measures in footwear evaluation, athletic training, clinical gait analysis, and pathology foot diagnosis. However, present plantar pressure measurement and analysis systems are more or less uncomfortable to wear and expensive. This paper presents an in-shoe plantar pressure measurement and analysis system based on a textile fabric sensor array, which is soft, light, and has a high-pressure sensitivity and a long service life. The sensors are connected with a soft polymeric board through conductive yarns and integrated into an insole. A stable data acquisition system interfaces with the insole, wirelessly transmits the acquired data to remote receiver through Bluetooth path. Three configuration modes are incorporated to gain connection with desktop, laptop, or smart phone, which can be configured to comfortably work in research laboratories, clinics, sport ground, and other outdoor environments. A real-time display and analysis software is presented to calculate parameters such as mean pressure, peak pressure, center of pressure (COP), and shift speed of COP. Experimental results show that this system has stable performance in both static and dynamic measurements.

  15. Detecting deterministic nature of pressure measurements from a turbulent combustor

    Science.gov (United States)

    Tony, J.; Gopalakrishnan, E. A.; Sreelekha, E.; Sujith, R. I.

    2015-12-01

    Identifying nonlinear structures in a time series, acquired from real-world systems, is essential to characterize the dynamics of the system under study. A single time series alone might be available in most experimental situations. In addition to this, conventional techniques such as power spectral analysis might not be sufficient to characterize a time series if it is acquired from a complex system such as a thermoacoustic system. In this study, we analyze the unsteady pressure signal acquired from a turbulent combustor with bluff-body and swirler as flame holding devices. The fractal features in the unsteady pressure signal are identified using the singularity spectrum. Further, we employ surrogate methods, with translational error and permutation entropy as discriminating statistics, to test for determinism visible in the observed time series. In addition to this, permutation spectrum test could prove to be a robust technique to characterize the dynamical nature of the pressure time series acquired from experiments. Further, measures such as correlation dimension and correlation entropy are adopted to qualitatively detect noise contamination in the pressure measurements acquired during the state of combustion noise. These ensemble of measures is necessary to identify the features of a time series acquired from a system as complex as a turbulent combustor. Using these measures, we show that the pressure fluctuations during combustion noise has the features of a high-dimensional chaotic data contaminated with white and colored noise.

  16. Untethered photonic sensor for wall pressure measurement.

    Science.gov (United States)

    Manzo, Maurizio; Ioppolo, Tindaro

    2015-05-15

    In this Letter, we study a novel untethered photonic wall pressure sensor that uses as sensing element a dome-shaped micro-scale laser. Since the sensor does not require any optical or electrical cabling, it allows measurements where cabling tends to be problematic. The micro-laser is made by a mixture of Trimethylolpropane Tri(3-mercaptopropionate), commercial name THIOCURE and Polyethylene (glycol) Diacrylate (PEGDA) mixed with a solution of rhodamine 6G. Two different volume ratios between the THIOCURE and the PEGDA are studied, since different ratios lead to different mechanical properties. In addition, two different sensor configurations are presented: (i) sensor coupled to a membrane, that allows differential wall pressure measurement and (ii) sensor without membrane that allows absolute wall pressure measurement. The sensitivity plots are presented in the paper for both sensor configurations and polymer ratios.

  17. Correction of static pressure on a research aircraft in accelerated flight using differential pressure measurements

    Directory of Open Access Journals (Sweden)

    A. R. Rodi

    2012-11-01

    Full Text Available A method is described that estimates the error in the static pressure measurement on an aircraft from differential pressure measurements on the hemispherical surface of a Rosemount model 858AJ air velocity probe mounted on a boom ahead of the aircraft. The theoretical predictions for how the pressure should vary over the surface of the hemisphere, involving an unknown sensitivity parameter, leads to a set of equations that can be solved for the unknowns – angle of attack, angle of sideslip, dynamic pressure and the error in static pressure – if the sensitivity factor can be determined. The sensitivity factor was determined on the University of Wyoming King Air research aircraft by comparisons with the error measured with a carefully designed sonde towed on connecting tubing behind the aircraft – a trailing cone – and the result was shown to have a precision of about ±10 Pa over a wide range of conditions, including various altitudes, power settings, and gear and flap extensions. Under accelerated flight conditions, geometric altitude data from a combined Global Navigation Satellite System (GNSS and inertial measurement unit (IMU system are used to estimate acceleration effects on the error, and the algorithm is shown to predict corrections to a precision of better than ±20 Pa under those conditions. Some limiting factors affecting the precision of static pressure measurement on a research aircraft are discussed.

  18. CFD modeling of the IRIS pressurizer dynamic

    Energy Technology Data Exchange (ETDEWEB)

    Sanz, Ronny R.; Montesinos, Maria E.; Garcia, Carlos; Bueno, Elizabeth D.; Mazaira, Leorlen R., E-mail: rsanz@instec.cu, E-mail: mmontesi@instec.cu, E-mail: cgh@instec.cu, E-mail: leored1984@gmail.com [Instituto Superior de Tecnologias y Ciencias Aplicadas (InSTEC), La Habana (Cuba); Bezerra, Jair L.; Lira, Carlos A.B. Oliveira, E-mail: jair.lima@ufpe.br, E-mail: cabol@ufpe.br [Universida Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Energia Nuclear

    2015-07-01

    Integral layout of nuclear reactor IRIS makes possible the elimination of the spray system, which is usually used to mitigate in-surge transient and also help to Boron homogenization. The study of transients with deficiencies in the Boron homogenization in this technology is very important, because they can cause disturbances in the reactor power and insert a strong reactivity in the core. The detailed knowledge of the behavior of multiphase multicomponent flows is challenging due to the complex phenomena and interactions at the interface. In this context, the CFD modeling is employed in the design of equipment in the nuclear industry as it allows predicting accidents or predicting their performance in dissimilar applications. The aim of the present research is to model the IRIS pressurizer's dynamic using the commercial CFD code CFX. A symmetric tri dimensional model equivalent to 1/8 of the total geometry was adopted to reduce mesh size and minimize processing time. The model considers the coexistence of four phases and also takes into account the heat losses. The relationships for interfacial mass, energy, and momentum transport are programmed and incorporated into CFX. Moreover, two subdomains and several additional variables are defined to monitoring the boron dilution sequences and condensation-evaporation rates in different control volumes. For transient states a non - equilibrium stratification in the pressurizer is considered. This paper discusses the model developed and the behavior of the system for representative transients sequences. The results of analyzed transients of IRIS can be applied to the design of pressurizer internal structures and components. (author)

  19. Molecular Dynamics Simulations of a Pressure-induced Glass Transition

    CERN Document Server

    Shumway, S L; Jonsson, H; Shumway, Shelly L.; Clarke, Andrew S.

    1994-01-01

    We simulate the compression of a two-component Lennard-Jones liquid at a variety of constant temperatures using a molecular dynamics algorithm in an isobaric-isothermal ensemble. The viscosity of the liquid increases with pressure, undergoing a broadened transition into a structurally arrested, amorphous state. This transition, like the more familiar one induced by cooling, is correlated with a significant increase in icosahedral ordering. In fact, the structure of the final state, as measured by an analysis of the bonding, is essentially the same in the glassy, frozen state whether produced by squeezing or by cooling under pressure. We have computed an effective hard-sphere packing fraction at the transition, defining the transition pressure or temperature by a cutoff in the diffusion constant, analogous to the traditional laboratory definition of the glass transition by an arbitrary, low cutoff in viscosity. The packing fraction at this transition point is not constant, but is consistently higher for runs c...

  20. Confounders of auscultatory blood pressure measurement.

    Science.gov (United States)

    Baker, R H; Ende, J

    1995-04-01

    The appropriate use of any test requires the clinician to appreciate that test's limitations. By recognizing the potential confounders of the auscultatory assessment of blood pressure, the clinician minimizes the likelihood of enacting therapeutic decisions based on inaccurate data. When approaching the treatment of a hypertensive patient, several points should be kept in mind. First, the measurement of persistent and severe hypertension in a patient receiving treatment who describes symptoms of orthostatic hypotension with apparently adequate standing blood pressure or who lacks corroborating retinal, echocardiographic, or electrocardiographic signs of hypertension should raise the concern of pseudohypertension or a white-coat response. Similarly, when one finds a normal or near-normal systolic blood pressure in a patient with a clinical picture consistent with severe hypertension, one should make a directed effort to look for an unrecognized auscultatory gap. Second, marked discrepancies in measurements as obtained by different operators or in different settings should raise concern of the white-coat response or methodologic errors by one operator, such as undercuffing, excessive pressure on the head of the stethoscope, rapid deflation of the cuff, or use of different arms. In treating hypertension in even the minimally obese patient, a special point must be made that an adequate size cuff be used for all blood pressure determinations. Third, when blood pressure is determined with the patient in any but the satndardized back-and-arm-supported seated position described above, the clinician should acknowledge the possibility that the position may alter the patient's classification. Fourth, the diagnosis and management of hypertension requires multiple measurements of blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

  1. PPOOLEX experiments on dynamic loading with pressure feedback

    Energy Technology Data Exchange (ETDEWEB)

    Puustinen, M.; Laine, J.; Raesaenen, A. (Lappeenranta Univ. of Technology, Nuclear Safety Research Unit (Finland))

    2011-01-15

    This report summarizes the results of the dynamic loading experiments (DYN series) carried out with the scaled down, two compartment PPOOLEX test facility designed and constructed at LUT. Steam was blown into the dry well compartment and from there through the DN200 vertical blowdown pipe to the condensation pool filled with sub-cooled water. The main purpose of the experiments was to study dynamic loads caused by different condensation modes. Particularly, the effect of counterpressure on loads due to pressure oscillations induced by chugging was of interest. Before the experiments the condensation pool was filled with isothermal water so that the blowdown pipe outlet was submerged by 1.03-1.11 m. The initial temperature of the pool water varied from 11 deg. C to 63 deg. C, the steam flow rate from 290 g/s to 1220 g/s and the temperature of incoming steam from 132 deg. C to 182 deg. C. Non-condensables were pushed from the dry well into the gas space of the wet well with a short discharge of steam before the recorded period of the experiments. As a result of this procedure, the system pressure was at an elevated level in the beginning of the actual experiments. An increased counterpressure was used in the last experiment of the series. The diminishing effect of increased system pressure on chugging intensity and on measured loads is evident from the results of the last experiment. The highest pressure pulses both inside the blowdown pipe and in the condensation pool were about half of those measured with a lower system pressure but otherwise with similar test parameters. The experiments on dynamic loading gave expected results. The loads experienced by pool structures depended strongly on the steam mass flow rate, pool water temperature and system pressure. The DYN experiments indicated that chugging and condensation within the blowdown pipe cause significant dynamic loads in case of strongly sub-cooled pool water. The level of pool water temperature is decisive

  2. PPOOLEX experiments on dynamic loading with pressure feedback

    Energy Technology Data Exchange (ETDEWEB)

    Puustinen, M.; Laine, J.; Raesaenen, A. (Lappeenranta Univ. of Technology, Nuclear Safety Research Unit (Finland))

    2011-01-15

    This report summarizes the results of the dynamic loading experiments (DYN series) carried out with the scaled down, two compartment PPOOLEX test facility designed and constructed at LUT. Steam was blown into the dry well compartment and from there through the DN200 vertical blowdown pipe to the condensation pool filled with sub-cooled water. The main purpose of the experiments was to study dynamic loads caused by different condensation modes. Particularly, the effect of counterpressure on loads due to pressure oscillations induced by chugging was of interest. Before the experiments the condensation pool was filled with isothermal water so that the blowdown pipe outlet was submerged by 1.03-1.11 m. The initial temperature of the pool water varied from 11 deg. C to 63 deg. C, the steam flow rate from 290 g/s to 1220 g/s and the temperature of incoming steam from 132 deg. C to 182 deg. C. Non-condensables were pushed from the dry well into the gas space of the wet well with a short discharge of steam before the recorded period of the experiments. As a result of this procedure, the system pressure was at an elevated level in the beginning of the actual experiments. An increased counterpressure was used in the last experiment of the series. The diminishing effect of increased system pressure on chugging intensity and on measured loads is evident from the results of the last experiment. The highest pressure pulses both inside the blowdown pipe and in the condensation pool were about half of those measured with a lower system pressure but otherwise with similar test parameters. The experiments on dynamic loading gave expected results. The loads experienced by pool structures depended strongly on the steam mass flow rate, pool water temperature and system pressure. The DYN experiments indicated that chugging and condensation within the blowdown pipe cause significant dynamic loads in case of strongly sub-cooled pool water. The level of pool water temperature is decisive

  3. A System for Unsteady Pressure Measurements Revisited

    NARCIS (Netherlands)

    Tijdeman, H.; Spiering, R.M.E.J.

    2003-01-01

    An overview is presented of some recent developments in the field of the design of effective sound absorbers. The first part deals with the application of socalled coupled tubes. For this purpose use is made of a system originally applied for unsteady pressure measurements on oscillating wind tunnel

  4. Miniature optical fiber pressure microsensors for in vivo measurement of intramuscular pressure

    Science.gov (United States)

    Cottler, P. S.; Blevins, D.; Averett, J.; Wavering, T. A.; Morrow, D. A.; Shin, A. Y.; Kaufman, K. R.

    2007-02-01

    An innovative fiber optic pressure microsensor has been developed that is based upon on Luna Innovations' patented extrinsic Fabry-Perot interferometric (EFPI) technique. The basic physics governing the operation of these sensors makes them relatively tolerant or immune to the effects of high-temperature, high-EMI, and highly-corrosive environments. Luna's pressure microsensor is extremely small, with an outer diameter of only 200 microns and a length of less than 1mm. The pressure microsensor has a high sensitivity that allows for sub-mmHg resolution over a dynamic range of 0-300 mmHg. The combination of these features makes this pressure microsensor ideal for medical applications where small size, high sensitivity and accuracy, EMI immunity, biocompatibility, and survivability (e.g. sterilizable - steam, ethylene oxide) are important. One example medical application of the pressure microsensor has been to adapt the microsensor for measurement of intramuscular pressure in vivo during active and passive muscle activation. Clinically it is difficult to study the in vivo mechanical properties of individual skeletal muscles for a variety of reasons. Initial experiments have demonstrated a correlation between intramuscular pressure and force. Such measurements can be a useful diagnostic tool for clinicians assessing muscular deficits in patients.

  5. Wavenumber-frequency Spectra of Pressure Fluctuations Measured via Fast Response Pressure Sensitive Paint

    Science.gov (United States)

    Panda, J.; Roozeboom, N. H.; Ross, J. C.

    2016-01-01

    The recent advancement in fast-response Pressure-Sensitive Paint (PSP) allows time-resolved measurements of unsteady pressure fluctuations from a dense grid of spatial points on a wind tunnel model. This capability allows for direct calculations of the wavenumber-frequency (k-?) spectrum of pressure fluctuations. Such data, useful for the vibro-acoustics analysis of aerospace vehicles, are difficult to obtain otherwise. For the present work, time histories of pressure fluctuations on a flat plate subjected to vortex shedding from a rectangular bluff-body were measured using PSP. The light intensity levels in the photographic images were then converted to instantaneous pressure histories by applying calibration constants, which were calculated from a few dynamic pressure sensors placed at selective points on the plate. Fourier transform of the time-histories from a large number of spatial points provided k-? spectra for pressure fluctuations. The data provides first glimpse into the possibility of creating detailed forcing functions for vibro-acoustics analysis of aerospace vehicles, albeit for a limited frequency range.

  6. Pore Pressure Measurements Inside Rubble Mound Breakwaters

    DEFF Research Database (Denmark)

    Helgason, Einar; Burcharth, H. F.; Grüne, Joachim

    2004-01-01

    The present paper presents pore pressure measurements from large scale model tests performed at the Large Wave Channel, Hannover, Germany and small scale model test performed at the Hydraulic & Coastal Engineering Laboratory, Aalborg University, Denmark. Information on pore pressure attenuation......, and compared to a damping model presented by Burcharth et al. (1999). Reasonable agreement is found when considering the difference in the grading and uniformity of the model core materials. Comparison between results obtained from small and large scale model tests showed no clear evidence of scale effects....

  7. Change in blood pressure in recovery phase after combined (static & dynamic) exercise

    OpenAIRE

    桑村, 由美; 志内, 哲也; 野村, 千景; 幸田, 貴美子; 小原, 繁

    1997-01-01

    It is well known that systolic blood pressure (SBP) elevate but diastolic blood pressure (DBP) do not elevate during dynamic exercise and in statlc isometrlc exercise DBP show respectable elevation. However,changes in SBP and DBP in recovery phase after exercise is unclear.In this study we measured SBP and DBP by auscultatory recording method during recovery phase for 10 minutes. Resting blood pressure was determined immediately before exercise. The exercise was a dynamic (p...

  8. A combination of thermal methods to assess coronary pressure and flow dynamics with a pressure-sensing guide wire.

    Science.gov (United States)

    van der Horst, Arjen; Van't Veer, Marcel; van der Sligte, Robin A M; Rutten, Marcel C M; Pijls, Nico H J; van de Vosse, Frans N

    2013-03-01

    Measurement of coronary pressure and absolute flow dynamics have shown great potential in discerning different types of coronary circulatory disease. In the present study, the feasibility of assessing pressure and flow dynamics with a combination of two thermal methods, developed in combination with a pressure-sensor-tipped guide wire, was evaluated in an in vitro coronary model. A continuous infusion thermodilution method was employed to determine the average flow, whereas a thermal anemometric method was utilized to assess the pressure and flow dynamics, simultaneously. In the latter method, the electrical power supplied to an element, kept at constant temperature above ambient temperature, was used as a measure for the shear rate. It was found that, using a single calibration function, the method was able to assess coronary pressure and flow dynamics for different flow amplitudes, heart rates, and different pressure wires. However, due to the fact that the thermal anemometric method cannot detect local shear rate reversal, the method was unable to reliably measure flow dynamics close to zero. Nevertheless, the combined methodology was able to reliably assess diastolic hemodynamics. The diastolic peak flow and average diastolic resistance could be determined with a small relative error of (8 ± 7)% and (7 ± 5)%, respectively.

  9. How to measure intraocular pressure: applanation tonometry

    Directory of Open Access Journals (Sweden)

    Nick Astbury

    2012-01-01

    Full Text Available Unless there is a contraindication (e.g. trauma or corneal ulcer, all adults attending an eye unit should have their intraocular pressure (IOP measured. Many people with glaucoma have no symptoms and do not know they have the condition. All children who have had cataract surgery should also have their IOP measured at every follow-up visit, if possible. Finding glaucoma early allows treatment to be given which will preserve sight. Although elevated IOP is not the only sign of glaucoma, measuring it is simple and quick to do. Applanation tonometry, using a Goldmann tonometer at a slit lamp, is the preferred method (the ‘gold standard’.

  10. Oscillometric blood pressure measurement: progress and problems.

    Science.gov (United States)

    van Montfrans, G A

    2001-12-01

    Oscillometric blood pressure measurement has become very popular, but although a number of devices have now passed both the Association for the Advancement of Medical Instrumentation and British Hypertension Society criteria, complacency with the state of the technique is as yet premature. In individual subjects, a substantial number of readings may deviate more than a clinically relevant 5 mmHg in devices that have earned a British Hypertension Society grade A rating. The marketing of pressure-wave-simulating devices is a welcome development as monitors can now be tested for reproducibility; an intra-device standard deviation of less than 2 mmHg has been proposed as the limit. Authors suggest that these simulators are currently better suited to intra- than between-device testing since they are not yet fully confident that the simulated waveforms are indistinguishable from the man-made pressure waves. Simulators should, however, be incorporated into our standard validation protocols in order eventually to obviate the human, fallible, factor in the validation protocols. The currently employed maximal amplitude algorithm has many drawbacks as the parameter identification points for systolic and diastolic pressure depend on many factors, for example pulse pressure, heart rate and arterial stiffness. These errors have now been demonstrated in clinical studies. Modern pattern recognition algorithms are being constructed but have not yet produced convincing results. As repeatedly stated, the development of a more robust and more widely applicable algorithm than the maximal amplitude approach should be allocated a high priority.

  11. Effect of change in large and fast solar wind dynamic pressure on geosynchronous magnetic field

    Institute of Scientific and Technical Information of China (English)

    Borodkova N L; Liu Jing-Bo; Huang Zhao-Hui; Zastenker G N; Wang Chi; Eiges P E

    2006-01-01

    We present a comparison of changes in large and sharp solar wind dynamic pressure, observed by several spacecraft,with fast disturbances in the magnetospheric magnetic field, measured by the geosynchronous satellites. More than 260 changes in solar wind pressure during the period 1996-2003 are selected for this study. Large statistics show that an increase (a decrease) in dynamic pressure always results in an increase (a decrease) in the magnitude of geosynchronous magnetic field. The amplitude of response to the geomagnetic field strongly depends on the location of observer relative to the noon meridian, the value of pressure before disturbance, and the change in amplitude of pressure.

  12. Robust pressure sensor for measurements in boundary layers of liquid fluids with medium total pressures

    Science.gov (United States)

    Beutel, T.; Ferreira, N.; Leester-Schädel, M.; Büttgenbach, S.

    2011-06-01

    In this work, the latest results of the design, fabrication and characterization of a new MEMS piezoresistive pressure sensor are presented. It is made of silicon using a boron diffusion process to create piezoresistors. Significant changes in the layout as well as in the micro-fabrication process have been made, e.g. anodic bonding of a Pyrex cover on the backside. These lead to a very precise pressure sensor, which is tailor made for high dynamic measurements in fluids with a total pressure up to 4 bar. This new piezoresistive pressure sensor has been developed in order to meet the special requirements of measurements in fluid mechanics, particularly with regard to the non-intrusive nature of the sensor. The sensor development, starting with the simulation of mechanical stresses within the diaphragm is described. These calculations have lead to an optimized placement of the piezoresistors in order to achieve a maximum sensitivity. The result of this work is a sensor which has well known properties. Important parameters including sensitivity, resonance frequency and maximum load are described precisely. These are necessary to enable new measurements in the boundary layer of fluids. The experiments and the initial results, e.g. its linearity and its dynamic capability are demonstrated in several figures.

  13. Unsteady Pressure and Velocity Measurements in Pumps

    Science.gov (United States)

    2006-11-01

    to reproduce the data with controlled experiments . For example, the rotor exit flow measured by means of a stationary high response probe will be...Turbomachinery by Means of High-Frequency Pressure Transducers. ASME, J. of Turbomachinery, Vol. 114, pp. 100-107. [3] Castorph, D. (1975): Messung ...Dreiß, A.; Kosyna, G. (1997): Experimental Investigations of Cavitation-States in a Radial Pump Impeller. JSME CENTENNIAL GRAND CONGRESS Proceedings of

  14. Structural Response Prediction: Full-field, Dynamic Pressure and Displacement Measurements of a Panel Excited by Shock Boundary-layer Interaction

    Science.gov (United States)

    2015-02-01

    house 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 61102F 6. AUTHOR(S) S. Michael Spottswood, Timothy J. Beberniss, and Thomas G. Eason (AFRL...International Symposium on Particle Image Velocimetry – PIV09, Melbourne , Victoria, Australia, August 25-28, 2009. 24 P.J. Schmid, “Dynamic mode

  15. Dynamic isolation technologies in negative pressure isolation wards

    CERN Document Server

    Xu, Zhonglin

    2017-01-01

    This book presents novel design principles and technologies for dynamic isolation based on experimental studies. These approaches have now become the local standard in Beijing and are currently being promoted for use nationwide. Further, the book provides details of measures and guidelines for the design process. Departing from the traditional understanding that isolation wards should be designed with high negative pressure, airtight doors and fresh air, it establishes the basis for designing biological clean rooms, including isolation wards, using a simple and convenient scientific approach. This book is intended for designers, engineers, researchers, hospital management staff and graduate students in heating ventilation air conditioning (HVAC), air cleaning technologies and related areas.

  16. High protein flexibility and reduced hydration water dynamics are key pressure adaptive strategies in prokaryotes

    KAUST Repository

    Martinez, N.

    2016-09-06

    Water and protein dynamics on a nanometer scale were measured by quasi-elastic neutron scattering in the piezophile archaeon Thermococcus barophilus and the closely related pressure-sensitive Thermococcus kodakarensis, at 0.1 and 40 MPa. We show that cells of the pressure sensitive organism exhibit higher intrinsic stability. Both the hydration water dynamics and the fast protein and lipid dynamics are reduced under pressure. In contrast, the proteome of T. barophilus is more pressure sensitive than that of T. kodakarensis. The diffusion coefficient of hydration water is reduced, while the fast protein and lipid dynamics are slightly enhanced with increasing pressure. These findings show that the coupling between hydration water and cellular constituents might not be simply a master-slave relationship. We propose that the high flexibility of the T. barophilus proteome associated with reduced hydration water may be the keys to the molecular adaptation of the cells to high hydrostatic pressure.

  17. High protein flexibility and reduced hydration water dynamics are key pressure adaptive strategies in prokaryotes

    Science.gov (United States)

    Martinez, N.; Michoud, G.; Cario, A.; Ollivier, J.; Franzetti, B.; Jebbar, M.; Oger, P.; Peters, J.

    2016-09-01

    Water and protein dynamics on a nanometer scale were measured by quasi-elastic neutron scattering in the piezophile archaeon Thermococcus barophilus and the closely related pressure-sensitive Thermococcus kodakarensis, at 0.1 and 40 MPa. We show that cells of the pressure sensitive organism exhibit higher intrinsic stability. Both the hydration water dynamics and the fast protein and lipid dynamics are reduced under pressure. In contrast, the proteome of T. barophilus is more pressure sensitive than that of T. kodakarensis. The diffusion coefficient of hydration water is reduced, while the fast protein and lipid dynamics are slightly enhanced with increasing pressure. These findings show that the coupling between hydration water and cellular constituents might not be simply a master-slave relationship. We propose that the high flexibility of the T. barophilus proteome associated with reduced hydration water may be the keys to the molecular adaptation of the cells to high hydrostatic pressure.

  18. Magnetospheric Cavity Modes Driven by Solar Wind Dynamic Pressure Fluctuations

    CERN Document Server

    Claudepierre, S G; Elkington, S R; Lotko, W; Hudson, M K; 10.1029/2009GL039045

    2010-01-01

    We present results from Lyon-Fedder-Mobarry (LFM) global, three-dimensional magnetohydrodynamic (MHD) simulations of the solar wind-magnetosphere interaction. We use these simulations to investigate the role that solar wind dynamic pressure fluctuations play in the generation of magnetospheric ultra-low frequency (ULF) pulsations. The simulations presented in this study are driven with idealized solar wind input conditions. In four of the simulations, we introduce monochromatic ULF fluctuations in the upstream solar wind dynamic pressure. In the fifth simulation, we introduce a continuum of ULF frequencies in the upstream solar wind dynamic pressure fluctuations. In this numerical experiment, the idealized nature of the solar wind driving conditions allows us to study the magnetospheric response to only a fluctuating upstream dynamic pressure, while holding all other solar wind driving parameters constant. The simulation results suggest that ULF fluctuations in the solar wind dynamic pressure can drive magnet...

  19. Dynamic measurement of forward scattering

    DEFF Research Database (Denmark)

    Appel-Hansen, Jørgen; Rusch, W.

    1975-01-01

    A dynamic method for the measurement of forward scattering in a radio anechoic chamber is described. The quantity determined is the induced-field-ratio (IFR) of conducting cylinders. The determination of the IFR is highly sensitive to 1) multiple scattering between the cylinder and the obpring...

  20. Dynamic High-Pressure Behavior of Hierarchical Heterogeneous Geological Materials

    Science.gov (United States)

    2016-04-01

    pressure -density Hugoniot plots for simulations using the ‘mix 5’ option, as will be presented later. The volume weighted option for mixed cells (refered...AFRL-AFOSR-VA-TR-2016-0150 Dynamic High- Pressure Behavior of Geological Materials Naresh Thadhani GEORGIA TECH RESEARCH CORPORATION Final Report 04...31-12-2015 4.  TITLE AND SUBTITLE Dynamic High- Pressure Behavior of Hierarchical Heterogeneous Geological Materials 5a.  CONTRACT NUMBER 5b.  GRANT

  1. Optic Fiber-Based Dynamic Pressure Sensor

    Institute of Scientific and Technical Information of China (English)

    Jiu-Lin Gan; Hai-Wen Cai; Jian-Xin Geng; Zheng-Qing Pan; Rong-Hui Qu; Zu-Jie Fang

    2008-01-01

    Weigh-in-Motion(WIM) technique is the process of measuring the dynamic tire forces of a moving vehicle and estimating the corresponding tire loads of the static vehicle. Compared with the static weigh station, WIM station is an efficient and cost effective choice that will minimize unneccessary stops and delay for truckers. The way to turn birefringence of single-mode fiber into a prime quality for a powerful and reliable sensor is shown. Preliminary results for the development of a weigh-in-motion (WIM) technique based on sagnac-loop sensor are presented. After a brief description of the sensor and its principle of operation, the theoretical model is developed. Then, a full characterization made in static conditions is presented.

  2. Dynamics and measurement of cavitation bubble

    Institute of Scientific and Technical Information of China (English)

    CHEN Weizhong; LIU Ya'nan; HUANG Wei; GAO Xianxian

    2006-01-01

    Based on the introduction of international progress, our investigations on acoustic cavitation have been reported. Firstly we considered the cavity's dynamics under the drive of the asymmetrical acoustic pressure. An aspheric dynamical model was proposed and a new stable and aspheric solution was found in numerical simulation of the theoretical framework of the aspheric model. Then, a dual Mie-scattering technique was developed to measure the cavity's aspheric pulsation. A significant asynchronous pulsation signal between two Mie-scattering channels was caught in the case of large cavity driven by low acoustic pressure. As a direct deduction, we observed an evidence of cavity's aspheric pulsation. Furthermore, we studied the dependency of the asynchronous pulsation signal on the various parameters, such as the amplitude and frequency of the driving acoustic pressure, and the surface tension, viscosity and gas concentration of the liquid. Finally, we introduced a new numeric imaging technique to measure the shapes of the periodic pulsation cavities. The time-resolution was in the order of 20 ns, one order of magnitude lower than that in the previous work, say, 200 ns.

  3. Tandem pressure measurements in a hostile environment

    Science.gov (United States)

    Higgins, P. B.

    1981-03-01

    Both carbon gages and quartz gages were calibrated with gas guns utilizing thin flyers. Experiments are described which compare the response of the two types of gages to a nonplaner stress pulse generated by the detonation of an explosive, silver acetylide-silver nitrate. It was concluded from 18 pairs of gages tested at three impulse levels that detonation of the explosive at no less than 100 points square cm would produce equal peak stress currents from the two types of gages within 25 percent. Impulse derived by integrating the pressure time profile from the carbon gages mounted on quartz gages did not agree with ballistic pendulum impulse data, possibly because of early cracking of quartz beneath the carbon gage. However, similar integration of the pressure profile of carbon gages mounted on flat aluminum, extrapolated for long times along a theoretical curve, gave an impulse practically equal to the directly measured impulse.

  4. Gait characteristics of children with spastic cerebral palsy assessed by dynamic plantar pressure measurement%动态足底压力检测痉挛型脑性瘫痪儿童步行时的特征

    Institute of Scientific and Technical Information of China (English)

    李海; 周安艳; 黄东锋; 丁建新; 江沁

    2007-01-01

    典型的双峰曲线,能得到典型足底压力双峰图的儿童,从其足底压力图中提取的各特征量数据能体现患儿步行时步态周期各时期的足底压力特征.%BACKGROUND:Pressure sensitive instrumented shoes are fast and easily used tools to measure ground reaction forces. Currently researches about the utilities of these systems in assessment of gait in children with neurological diseases have been started to run.OBJECTIVE: To find the gait characteristics of dynamic plantar pressure in children with spastic cerebral palsy. DESIGN: A cross-sectional study.SETTINGS: Department of Rehabilitation, Songgang People's Hospital; Department of Rehabilitation, Shenzhen Children's Hospital; Department of Rehabilitation Medicine, the First Affiliated Hospital of Sun Yat-sen University. PARTICIPANTS: ① Patient group: Twenty children with spastic cerebral palsy were selected from Shenzhen Children's Hospital from May 2004 to April 2005, including 9 boys and 11 girls, aged 26-66 months old, and they all could walk for more than 10 m independently. ② Normal control group: 52 healthy children with normal walking ability were enrolled, including 28 boys.and 24 girls, aged 35-76 months old.METHODS: Ultraflex gait analysis system was used to perform continuous plantar pressure tests of both groups of children. Diagram and data of dynamic plantar pressures in gait were recorded and analyzed with a computer. MAIN OUTCOME MEASURES: ① 10 sequential gait cycles were chosen from the continuous stable steps to calculate the average data with the software; ② Differences of the characteristic parameters of plantar pressure curve between the two groups.RESULTS: ① The curves of plantar pressure to time of testees in the normal control group were of the wave shapes with two peaks and one valley. Half of the CP children could not perform the two-peak shape pressure curve in the gait analysis. One kind of abnormal plantar pressure curve style was a wave shape

  5. Hybrid Optical Unobtrusive Blood Pressure Measurements

    Directory of Open Access Journals (Sweden)

    Guangfei Zhang

    2017-07-01

    Full Text Available Blood pressure (BP is critical in diagnosing certain cardiovascular diseases such as hypertension. Some previous studies have proved that BP can be estimated by pulse transit time (PTT calculated by a pair of photoplethysmography (PPG signals at two body sites. Currently, contact PPG (cPPG and imaging PPG (iPPG are two feasible ways to obtain PPG signals. In this study, we proposed a hybrid system (called the ICPPG system employing both methods that can be implemented on a wearable device, facilitating the measurement of BP in an inconspicuous way. The feasibility of the ICPPG system was validated on a dataset with 29 subjects. It has been proved that the ICPPG system is able to estimate PTT values. Moreover, the PTT measured by the new system shows a correlation on average with BP variations for most subjects, which could facilitate a new generation of BP measurement using wearable and mobile devices.

  6. Experimental investigation of dynamic effects in capillary pressure: Grain size dependency and upscaling

    Science.gov (United States)

    Camps-Roach, Geremy; O'Carroll, Denis M.; Newson, Timothy A.; Sakaki, Toshihiro; Illangasekare, Tissa H.

    2010-08-01

    The macroscopic flow equations used to predict two-phase flow typically utilizes a capillary pressure-saturation relationship determined under equilibrium conditions. Theoretical reasoning, experimental evidence, and numerical modeling results have indicated that when one fluid phase replaces another fluid, this relationship may not be unique but may depend on the rate at which the phase saturations change in response to changes in phase pressures. This nonuniqueness likely depends on a variety of factors including soil-fluid properties and possibly physical scale. To quantify this dependency experimentally, direct measurements of equilibrium and dynamic capillary pressure-saturation relationships were developed for two Ottawa sands with different grain sizes using a 20 cm long column. A number of replicate air-water experiments were conducted to facilitate statistical comparison of capillary pressure-saturation relationships. Water and air pressures and phase saturations were measured at three different vertical locations in the sand column under different desaturation rates (1) to measure local capillary pressure-saturation relationships (static and dynamic); (2) to quantify the dynamic coefficient τ, a measure of the magnitude of observed dynamic effects, as a function of water saturation for different grain sizes and desaturation rates; (3) to investigate the importance of grain size on measured dynamic effects; and (4) to assess the importance of sample scale on the magnitude of dynamic effects in capillary pressure. A comparison of the static and dynamic Pc-Sw relationships showed that at a given water saturation, capillary pressure measured under transient water drainage conditions is statistically larger than capillary pressure measured under equilibrium or static conditions, consistent with thermodynamic theory. The dynamic coefficient τ, used in the expression relating the static and dynamic capillary pressures to the desaturation rate was dependant on

  7. The correlations of ions density with geomagnetic activity and solar dynamic pressure in cusp region

    Institute of Scientific and Technical Information of China (English)

    GUO JianGuang; SHI JianKui; ZHANG TieLong; LIU ZhenXing; A. FAZAKERLEY; H. R(E)ME; Ⅰ. DANDOURAS; E. LUCEK

    2007-01-01

    A statistical study of the properties of ions (O+, He+ and H+) measured by the Cluster-Ⅱ in cusp region as a function of the solar wind dynamic pressure and geomagnetic index Kp respectively was made during the summer and fall of 2001 -2003. The main results are that: (1) O+ ion density responds in a significant way to geomagnetic index Kp, and He+ ion density is not correlated with geomagnetic index Kp,both of them have a significant positive correlation with solar wind dynamic pressure; (2) H+ ion density is also observed to increase with solar wind dynamic pressure, and not correlated with geomagnetic index Kp.

  8. Modeling plasma pressure anisotropy's effect on Saturn's global magnetospheric dynamics

    Science.gov (United States)

    Tilley, M.; Harnett, E. M.; Winglee, R.

    2014-12-01

    A 3D multi-fluid, multi-scale plasma model with a complete treatment of plasma pressure anisotropy is employed to study global magnetospheric dynamics at Saturn. Cassini has observed anisotropies in the Saturnian magnetosphere, and analyses have showed correlations between anisotropy and plasma convection, ring current structure and intensity, confinement of plasma to the equatorial plane, as well as mass transport to the outer magnetosphere. The energization and transport of plasma within Saturn's magnetosphere is impactful upon the induced magnetic environments and atmospheres of potentially habitable satellites such as Enceladus and Titan. Recent efforts to couple pressure anisotropy with 3D multi-fluid plasma modeling have shown a significant move towards matching observations for simulations of Earth's magnetosphere. Our approach is used to study the effects of plasma pressure anisotropy on global processes of the Saturnian magnetosphere such as identifying the effect of pressure anisotropy on the centrifugal interchange instability. Previous simulation results have not completely replicated all aspects of the structure and formation of the interchange 'fingers' measured by Cassini at Saturn. The related effects of anisotropy, in addition to those mentioned above, include contribution to formation of MHD waves (e.g. reduction of Alfvén wave speed) and formation of firehose and mirror instabilities. An accurate understanding of processes such as the interchange instability is required if a complete picture of mass and energy transport at Saturn is to be realized. The results presented here will detail how the inclusion of a full treatment of pressure anisotropy for idealized solar wind conditions modifies the interchange structure and shape of the tail current sheet. Simulation results are compared to observations made by Cassini.

  9. Constant pressure and temperature discrete-time Langevin molecular dynamics.

    Science.gov (United States)

    Grønbech-Jensen, Niels; Farago, Oded

    2014-11-21

    We present a new and improved method for simultaneous control of temperature and pressure in molecular dynamics simulations with periodic boundary conditions. The thermostat-barostat equations are built on our previously developed stochastic thermostat, which has been shown to provide correct statistical configurational sampling for any time step that yields stable trajectories. Here, we extend the method and develop a set of discrete-time equations of motion for both particle dynamics and system volume in order to seek pressure control that is insensitive to the choice of the numerical time step. The resulting method is simple, practical, and efficient. The method is demonstrated through direct numerical simulations of two characteristic model systems-a one-dimensional particle chain for which exact statistical results can be obtained and used as benchmarks, and a three-dimensional system of Lennard-Jones interacting particles simulated in both solid and liquid phases. The results, which are compared against the method of Kolb and Dünweg [J. Chem. Phys. 111, 4453 (1999)], show that the new method behaves according to the objective, namely that acquired statistical averages and fluctuations of configurational measures are accurate and robust against the chosen time step applied to the simulation.

  10. Pressure measurements on a pitching airfoil in a water channel

    Science.gov (United States)

    Conger, Rand N.; Ramaprian, B. R.

    1994-01-01

    Measurements of unsteady pressures over a symmetric NACA 0015 airfoil performing pitching maneuvers are reported. The tests were performed in an open-surface water channel specially constructed for this purpose. The design of the apparatus allowed the pressure measurements to be made to a very high degree of spatial and temporal resolution. Reynolds numbers in the range of 5.2 x 10(exp 4) to 2.2 x 10(exp 5) were studied. Although the results qualitatively agreed with earlier studies performed at similar Reynolds numbers, the magnitudes of pressure and aerodynamic forces measured were observed to be much larger than those measured in ealier pitchup studies. They were found, in fact, to be closer to those obtained in some recent high-Reynolds-number experiments. This interesting behavior, which was suspected to be caused by the relatively high freestream turbulence level in the water channel, was explored in some detail. In addition, several issues like the quasisteady and dynamic effects of the pitching process are discussed. The experimental data are all archived and are available for use as a database.

  11. Simulation Study of AC Contactor Dynamic Contacts Contact Pressure Based on ADAMS

    Directory of Open Access Journals (Sweden)

    Gu Yungao

    2015-01-01

    Full Text Available A multi-body dynamics simulation model of CJ20-25 AC contactor was established with Pro/E(Pro/Engineerin this paper. A coupling simulation with machine, electric, magnetic on the contactor has been achieved in this model. Dynamic parameters which were called use the secondary development technology of ADAMS. The dynamic contact pressure signal of an AC contactor was obtained with ADAMS’s own simultaneous solution such as electromagnetic suction, kinematics and dynamics equations. The simulation results and actual measurement of contactor contact pressure signals are very similar. However, the complexity of the measured contacts vibration is greater than the simulation results because the actual working condition is more complex. This result provides a theoretical foundation to the dynamic contacts contact pressure test.

  12. Polyunsaturation in lipid membranes: dynamic properties and lateral pressure profiles.

    Science.gov (United States)

    Ollila, Samuli; Hyvönen, Marja T; Vattulainen, Ilpo

    2007-03-29

    We elucidate the influence of unsaturation on single-component membrane properties, focusing on their dynamical aspects and lateral pressure profiles across the membrane. To this end, we employ atomistic molecular dynamics simulations to study five different membrane systems with varying degrees of unsaturation, starting from saturated membranes and systematically increasing the level of unsaturation, ending up with a bilayer of phospholipids containing the docosahexaenoic acid. For an increasing level of unsaturation, we find considerable effects on dynamical properties, such as accelerated dynamics of the phosphocholine head groups and glycerol backbones and speeded up rotational dynamics of the lipid molecules. The lateral pressure profile is found to be altered by the degree of unsaturation. For an increasing number of double bonds, the peak in the middle of the bilayer decreases. This is compensated for by changes in the membrane-water interface region in terms of increasing peak heights of the lateral pressure profile. Implications of the findings are briefly discussed.

  13. Pyrometric fuel particle measurements in pressurized reactors

    Energy Technology Data Exchange (ETDEWEB)

    Joutsenoja, T.; Stenberg, J.; Hernberg, R.; Aho, M.; Richard, J.-R.; Mallet, C.; Bonn, B. [Tampere University of Technology, Tampere (Finland). Dept. of Physics

    1998-12-31

    A fibre-optic two-colour pyrometric technique for fuel particle temperature and size measurement is modified and applied to three pressurised reactors of different type in Finland, Germany and France. A modification of the pyrometric method for simultaneous in situ measurement of the temperature and size of individual pulverised coal particles at the pressurised entrained flow reactor of VTT Energy in Jyvaskyla was developed and several series of measurements were made in order to study the effects of oxygen concentration (3-30 vol%) and pressure (0.2-1.0 MPa) on the particle temperature. The fuels used in the experiments were Westerholt, Polish and Gottelborn hvb coals. Gardanne lignite and Niederberg anthracite. The initial nominal fuel particle size varied in the experiments from 70 to 250 {mu}m and the gas temperature was typically 1173 K. For the anthracite also the effects of gas temperature (1073-1423 K) and CO{sub 2} concentration (6-80 vol%) were studied. In Orleans a fibre-optic pyrometric device was installed to a pressurised thermogravimetric reactor of CNRS and the two-colour temperatures of fuel samples were measured. The fuel in the experiments was pulverized Gottelborn char. The reliability of optical temperature measurement in this particular application was analysed. In Essen a fibre-optic pyrometric technique that is capable to measure bed and fuel particle temperatures was applied to an atmospheric fluidised bed reactor of DMT. The effects of oxygen concentration (3-8 vol%) and bed temperature (1123-1193 K) on the fuel particle temperature were studied. The fuels in these were Westerholt coal and char and EBV-coal. 17 refs., 21 figs., 3 tabs.

  14. Fluid-filled blood pressure measurement systems.

    Science.gov (United States)

    Li, J K; van Brummelen, A G; Noordergraaf, A

    1976-05-01

    The performance of catheter-manometer systems for the measurement of pulsatile pressure has been evaluated by both experimental techniques and theoretical considerations. The former approach has shown, on occasion, multiple maxima in the amplitude response. The latter has been approached in a variety of ways, ranging from extreme lumping to application of transmission line theory while employing different configurations in the system's representation. Multiple maxima have also been seen, The present paper identifies the sources of the differences found and compares the relative merits of various theoretical approaches. It introduces the compliance of the system as a figure of merit and provides a simple first-order approximation formula for evaluation of the quality of a system. Damping and impedance matching to improve the system's frequency response were studied. It was found that they were not needed in a very stiff or a very compliant system, nor should one worry about the representation of such a system.

  15. Evaluating road surface conditions using dynamic tire pressure sensor

    Science.gov (United States)

    Zhao, Yubo; Wu, H. Felix; McDaniel, J. Gregory; Wang, Ming L.

    2014-03-01

    In order to best prioritize road maintenance, the level of deterioration must be known for all roads in a city's network. Pavement Condition Index (PCI) and International Roughness Index (IRI) are two standard methods for obtaining this information. However, IRI is substantially easier to measure. Significant time and money could be saved if a method were developed to estimate PCI from IRI. This research introduces a new method to estimate IRI and correlate IRI with PCI. A vehicle-mounted dynamic tire pressure sensor (DTPS) system is used. The DTPS measures the signals generated from the tire/road interaction while driving. The tire/road interaction excites surface waves that travel through the road. DTPS, which is mounted on the tire's valve stem, measures tire/road interaction by analyzing the pressure change inside the tire due to the road vibration, road geometry and tire wall vibration. The road conditions are sensible to sensors in a similar way to human beings in a car. When driving on a smooth road, tire pressure stays almost constant and there are minimal changes in the DTPS data. When driving on a rough road, DTPS data changes drastically. IRI is estimated from the reconstructed road profile using DTPS data. In order to correlate IRI with PCI, field tests were conducted on roads with known PCI values in the city of Brockton, MA. Results show a high correlation between the estimated IRI values and the known PCI values, which suggests that DTPS-based IRI can provide accurate predictions of PCI.

  16. Definition of Measure-theoretic Pressure Using Spanning Sets

    Institute of Scientific and Technical Information of China (English)

    Lian Fa HE; Jin Feng LV; Li Na ZHOU

    2004-01-01

    We introduce a new definition of measure-theoretic pressure for ergodic measures of continuous maps on a compact metric space. This definition is similar to those of topological pressure involving spanning sets. As an application, for C1+α(α> 0) diffeomorphisms of a compact manifold, we study the relationship between the measure-theoretic pressure and the periodic points.

  17. Dynamics of inner ear pressure change caused by intracranial pressure manipulation in the guinea pig

    NARCIS (Netherlands)

    Thalen, EO; Wit, HP; Segenhout, JM; Albers, FWJ

    2001-01-01

    Previous studies have shown that pressure changes in the cerebrospinal fluid compartment are transmitted to the inner ear. The main route for pressure transfer is the cochlear aqueduct, about which little is known with regard to its dynamic properties. In the present study, sudden intracranial press

  18. Dynamics of inner ear pressure change caused by intracranial pressure manipulation in the guinea pig

    NARCIS (Netherlands)

    Thalen, EO; Wit, HP; Segenhout, JM; Albers, FWJ

    Previous studies have shown that pressure changes in the cerebrospinal fluid compartment are transmitted to the inner ear. The main route for pressure transfer is the cochlear aqueduct, about which little is known with regard to its dynamic properties. In the present study, sudden intracranial

  19. Nonlinear radiation pressure dynamics in an optomechanical crystal

    CERN Document Server

    Krause, Alex G; Ludwig, Max; Safavi-Naeini, Amir H; Chan, Jasper; Marquardt, Florian; Painter, Oskar

    2015-01-01

    Utilizing a silicon nanobeam optomechanical crystal, we investigate the attractor diagram arising from the radiation pressure interaction between a localized optical cavity at $\\lambda = 1552$nm and a mechanical resonance at $\\omega/2\\pi = 3.72$GHz. At a temperature of $T \\approx 10$K, highly nonlinear driving of mechanical motion is observed via continuous wave optical pumping. Introduction of a time-dependent (modulated) optical pump is used to steer the system towards an otherwise inaccessible dynamically stable attractor in which mechanical self-oscillation occurs for an optical pump red-detuned from the cavity resonance. An analytical model incorporating thermo-optic effects due to optical absorption heating is developed, and found to accurately predict the measured device behavior.

  20. Osmosis-based pressure generation: dynamics and application.

    Science.gov (United States)

    Bruhn, Brandon R; Schroeder, Thomas B H; Li, Suyi; Billeh, Yazan N; Wang, K W; Mayer, Michael

    2014-01-01

    This paper describes osmotically-driven pressure generation in a membrane-bound compartment while taking into account volume expansion, solute dilution, surface area to volume ratio, membrane hydraulic permeability, and changes in osmotic gradient, bulk modulus, and degree of membrane fouling. The emphasis lies on the dynamics of pressure generation; these dynamics have not previously been described in detail. Experimental results are compared to and supported by numerical simulations, which we make accessible as an open source tool. This approach reveals unintuitive results about the quantitative dependence of the speed of pressure generation on the relevant and interdependent parameters that will be encountered in most osmotically-driven pressure generators. For instance, restricting the volume expansion of a compartment allows it to generate its first 5 kPa of pressure seven times faster than without a restraint. In addition, this dynamics study shows that plants are near-ideal osmotic pressure generators, as they are composed of many small compartments with large surface area to volume ratios and strong cell wall reinforcements. Finally, we demonstrate two applications of an osmosis-based pressure generator: actuation of a soft robot and continuous volume delivery over long periods of time. Both applications do not need an external power source but rather take advantage of the energy released upon watering the pressure generators.

  1. Osmosis-based pressure generation: dynamics and application.

    Directory of Open Access Journals (Sweden)

    Brandon R Bruhn

    Full Text Available This paper describes osmotically-driven pressure generation in a membrane-bound compartment while taking into account volume expansion, solute dilution, surface area to volume ratio, membrane hydraulic permeability, and changes in osmotic gradient, bulk modulus, and degree of membrane fouling. The emphasis lies on the dynamics of pressure generation; these dynamics have not previously been described in detail. Experimental results are compared to and supported by numerical simulations, which we make accessible as an open source tool. This approach reveals unintuitive results about the quantitative dependence of the speed of pressure generation on the relevant and interdependent parameters that will be encountered in most osmotically-driven pressure generators. For instance, restricting the volume expansion of a compartment allows it to generate its first 5 kPa of pressure seven times faster than without a restraint. In addition, this dynamics study shows that plants are near-ideal osmotic pressure generators, as they are composed of many small compartments with large surface area to volume ratios and strong cell wall reinforcements. Finally, we demonstrate two applications of an osmosis-based pressure generator: actuation of a soft robot and continuous volume delivery over long periods of time. Both applications do not need an external power source but rather take advantage of the energy released upon watering the pressure generators.

  2. Prediction of Dynamic Wellbore Pressure in Gasified Fluid Drilling

    Institute of Scientific and Technical Information of China (English)

    Wang Zhiming; Ping Liqiu; Zou Ke

    2007-01-01

    The basis of designing gasified drilling is to understand the behavior of gas/liquid two-phase flow in the wellbore. The equations of mass and momentum conservation and equation of fluid flow in porous media were used to establish a dynamic model to predict weIlbore pressure according to the study results of Ansari and Beggs-Brill on gas-liquid two-phase flow. The dynamic model was solved by the finite difference approach combined with the mechanistic steady state model. The mechanistic dynamic model was numerically implemented into a FORTRAN 90 computer program and could simulate the coupled flow of fluid in wellbore and reservoir. The dynamic model revealed the effects of wellhead back pressure and injection rate of gas/liquid on bottomhole pressure. The model was validated against full-scale experimental data, and its 5.0% of average relative error could satisfy the accuracy requirements in engineering design.

  3. Evaluation of gastric pressures as an indirect method for measurement of intraabdominal pressures in the horse.

    Science.gov (United States)

    Munsterman, Amelia S; Hanson, Russell Reid

    2011-02-01

    To develop an indirect method for measurement of intraabdominal pressures in the standing horse using measurement of gastric pressures as a less invasive technique, and to compare this method with direct intraabdominal pressures obtained from the peritoneal cavity. Prospective, experimental study. University-based equine research facility. Ten healthy adult horses, 7 geldings and 3 mares. Gastric pressures were measured using a nasogastric tube with a U-tube manometry technique, while intraperitoneal pressures were measured with a peritoneal cannula. Measurements of intraabdominal pressure were obtained by both methods, simultaneously, and were evaluated using 5 increasing volumes of fluid infused into the stomach (0, 400, 1,000, 2,000, and 3,000 mL). Bias and agreement between the 2 methods were determined using Bland-Altman analysis and Lin's concordance correlation coefficients. Mean gastric pressure was 14.44 ± 4.69 cm H(2)O and ranged from 0 to 25.8 cm H(2)O. Intraperitoneal pressure measurements were generally subatmospheric, and ranged from -6.6 to 3.1 cm H(2) O (mean ± SD, -1.59 ± 2.09 cm H(2)O). Measurements of intraperitoneal pressures were repeatable; however, intra- and interindividual variance was significantly larger for measurements of gastric pressures. The mean and relative bias for comparison between the 2 techniques was 15.9 ± 5.3 cm H(2)O and 244.3 ± 199.2%, respectively. The Lin's concordance correlation coefficient between gastric and intraperitoneal pressures was -0.003 but this was not statistically significant (P=0.75). There was no statistical concordance between measurements of intraabdominal pressure using gastric and intraperitoneal pressure measurement, indicating that gastric pressures cannot be substituted for intraperitoneal pressure measurement. Direct measurement of intraperitoneal pressures may be a more consistent method for comparison of intraabdominal pressures between horses, due to less variability within and between

  4. Organic Electroluminescent Sensor for Pressure Measurement

    Directory of Open Access Journals (Sweden)

    Tomohide Niimi

    2012-10-01

    Full Text Available We have proposed a novel concept of a pressure sensor called electroluminescent pressure sensor (ELPS based on oxygen quenching of electroluminescence. The sensor was fabricated as an organic light-emitting device (OLED with phosphorescent dyes whose phosphorescence can be quenched by oxygenmolecules, and with a polymer electrode which permeates oxygen molecules. The sensor was a single-layer OLED with Platinum (II octaethylporphine (PtOEP doped into poly(vinylcarbazole (PVK as an oxygen sensitive emissive layer and poly(3,4-ethylenedioxythiophene mixed with poly(styrenesulfonate (PEDOT:PSS as an oxygen permeating polymer anode. The pressure sensitivity of the fabricated ELPS sample was equivalent to that of the sensor excited by an illumination light source. Moreover, the pressure sensitivity of the sensor is equivalent to that of conventional pressure-sensitive paint (PSP, which is an optical pressure sensor based on photoluminescence.

  5. Intramuscular Pressure Measurement During Locomotion in Humans

    Science.gov (United States)

    Ballard, Ricard E.

    1996-01-01

    To assess the usefulness of intramuscular pressure (IMP) measurement for studying muscle function during gait, IMP was recorded in the soleus and tibialis anterior muscles of ten volunteers during, treadmill walking, and running using transducer-tipped catheters. Soleus IMP exhibited single peaks during late-stance phase of walking (181 +/- 69 mmHg, mean +/- S.E.) and running (269 +/- 95 mmHg). Tibialis anterior IMP showed a biphasic response, with the largest peak (90 +/- 15 mmHg during walking and 151 +/- 25 mmHg during running) occurring shortly after heel strike. IMP magnitude increased with gait speed in both muscles. Linear regression of soleus IMP against ankle joint torque obtained by a dynamometer in two subjects produced linear relationships (r = 0.97). Application of these relationships to IMP data yielded estimated peak soleus moment contributions of 0.95-165 Nm/Kg during walking, and 1.43-2.70 Nm/Kg during running. IMP results from local muscle tissue deformations caused by muscle force development and thus, provides a direct, practical index of muscle function during locomotion in humans.

  6. Pressure Dynamic Characteristics of Pressure Controlled Ventilation System of a Lung Simulator

    Directory of Open Access Journals (Sweden)

    Yan Shi

    2014-01-01

    Full Text Available Mechanical ventilation is an important life support treatment of critically ill patients, and air pressure dynamics of human lung affect ventilation treatment effects. In this paper, in order to obtain the influences of seven key parameters of mechanical ventilation system on the pressure dynamics of human lung, firstly, mechanical ventilation system was considered as a pure pneumatic system, and then its mathematical model was set up. Furthermore, to verify the mathematical model, a prototype mechanical ventilation system of a lung simulator was proposed for experimental study. Last, simulation and experimental studies on the air flow dynamic of the mechanical ventilation system were done, and then the pressure dynamic characteristics of the mechanical system were obtained. The study can be referred to in the pulmonary diagnostics, treatment, and design of various medical devices or diagnostic systems.

  7. Intraglottal velocity and pressure measurements in a hemilarynx model.

    Science.gov (United States)

    Oren, Liran; Gutmark, Ephraim; Khosla, Sid

    2015-02-01

    Determining the mechanisms of self-sustained oscillation of the vocal folds requires characterization of the pressures produced by intraglottal aerodynamics. Because most of the intraglottal aerodynamic forces cannot be measured in a tissue model of the larynx, current understanding of vocal fold vibration mechanism is derived from mechanical, analytical, and computational models. Previous studies have computed intraglottal pressures from measured intraglottal velocity fields and intraglottal geometry; however, this technique for determining pressures is not yet validated. In this study, intraglottal pressure measurements taken in a hemilarynx model are compared with pressure values that are computed from simultaneous velocity measurements. The results showed that significant negative pressure formed near the superior aspect of the folds during closing, which agrees with previous measurements in other hemilarynx models. Intraglottal velocity measurements show that the flow near the superior aspect separates from the glottal wall during closing and may develop into a vortex, which further augments the magnitude of negative pressure. Intraglottal pressure distributions, computed by solving the pressure Poisson equation, showed good agreement with pressure measurements. The match between the pressure computations and its measurements validates the current technique, which was previously used to estimate intraglottal pressure distribution in a full larynx model.

  8. Retention curves measured using pressure plate and pressure membrane apparatus

    DEFF Research Database (Denmark)

    Hansen, Morten Hjorslev

    This report presents a proposal for a test method for the measurement of the retention curve, especially in the high moisture content range, and the pore size distribution of building materials. The test method includes the measurement of apparent density, solid density, and open porosity. The re...

  9. Turbulent pressure fluctuations measured during CHATS

    Science.gov (United States)

    Steven P. Oncley; William J. Massman; Edward G. Patton

    2008-01-01

    Fast-response pressure fluctuations were included in the Canopy Horizontal Array of Turbulence Study (CHATS) at several heights within and just above the canopy in a walnut orchard. Two independent systems were intercompared and then separated. We present an evaluation of turbulence statistics - including the pressure transport term in the turbulence kinetic energy...

  10. Direct measurements of the pressure distribution along the contact area during droplet impact

    Science.gov (United States)

    Nguyen, Thanh-Vinh; Matsumoto, Kiyoshi; Shimoyama, Isao

    2016-11-01

    We report direct measurements of the pressure distribution on the contact area during the impact of a droplet on a micropillar array. The measurements were realized using an array of MEMS-based force sensors fabricated underneath the micropillars. We show that immediately after the droplet hits the surface, the pressure becomes maximum at the center of the contact area and this maximum pressure value is more than 10 times larger than the dynamic pressure. This result emphasizes the effect of water-hammer-type pressure during the early stage of the impact. Furthermore, our measurement results demonstrate that the critical pressure associated with Cassie-Wenzel transition agrees well with the maximum capillary pressure of the micropillar array.

  11. [An integrated system of blood pressure measurement with bluetooth communication].

    Science.gov (United States)

    Wang, Wei; Wang, Jing; Sun, Hongyang; Xu, Zuyang; Chai, Xinyu

    2012-07-01

    The development of the integrated blood pressure system with bluetooth communication function is introduced. Experimental results show that the system can complete blood pressure measurement and data transmission wireless effectively, which can be used in m-Health in future.

  12. Pressure measurements on a rectangular wing with a NACA0012 airfoil during conventional flutter

    Science.gov (United States)

    Rivera, Jose A., Jr.; Dansberry, Bryan E.; Durham, Michael H.; Bennett, Robert M.; Silva, Walter A.

    1992-01-01

    The Structural Dynamics Division at NASA LaRC has started a wind tunnel activity referred to as the Benchmark Models Program. The primary objective of the program is to acquire measured dynamic instability and corresponding pressure data that will be useful for developing and evaluating aeroelastic type CFD codes currently in use or under development. The program is a multi-year activity that will involve testing of several different models to investigate various aeroelastic phenomena. The first model consisted of a rigid semispan wing having a rectangular planform and a NACA 0012 airfoil shape which was mounted on a flexible two degree-of-freedom mount system. Two wind-tunnel tests were conducted with the first model. Several dynamic instability boundaries were investigated such as a conventional flutter boundary, a transonic plunge instability region near Mach = 0.90, and stall flutter. In addition, wing surface unsteady pressure data were acquired along two model chords located at the 60 to 95-percent span stations during these instabilities. At this time, only the pressure data for the conventional flutter boundary is presented. The conventional flutter boundary and the wing surface unsteady pressure measurements obtained at the conventional flutter boundary test conditions in pressure coefficient form are presented. Wing surface steady pressure measurements obtained with the model mount system rigidized are also presented. These steady pressure data were acquired at essentially the same dynamic pressure at which conventional flutter had been encountered with the mount system flexible.

  13. Auscultatory versus oscillometric measurement of blood pressure in octogenarians

    DEFF Research Database (Denmark)

    Rosholm, Jens-Ulrik; Pedersen, Sidsel Arnspang; Matzen, Lars;

    2012-01-01

    Auscultatory measurement using a sphygmomanometer has been the predominant method for clinical estimation of blood pressure, but it is now rapidly being replaced by oscillometric measurement.......Auscultatory measurement using a sphygmomanometer has been the predominant method for clinical estimation of blood pressure, but it is now rapidly being replaced by oscillometric measurement....

  14. Indirect blood pressure measurement: a need to reassess.

    Science.gov (United States)

    Anderson, F D; Cunningham, S G; Maloney, J P

    1993-07-01

    Indirect blood pressure measurement is the assessment tool used most frequently in epidemiological studies and hypertension management in the population at large. To review indirect blood pressure measurement within the context of nursing practice. Nurses are not following recommended American Heart Association measurement guidelines. A national program of certification in indirect blood pressure measurement, similar to that of basic and advanced cardiac life support, is needed. An initial approach to evaluating present practice is also suggested.

  15. [Plantar pressure measurement in children and youths during sports activities].

    Science.gov (United States)

    Lampe, R; Mitternacht, J; Gerdesmeyer, L; Gradinger, R

    2005-01-01

    The aim of this study was to consider whether changes occur in the foot area while under repeated physical stress and if they are age related. In addition it interests what consequences this might have in regard to proper shoe wear. The subjects for this study consisted of 15 children and youths aged between 4 and 16 years. The plantar pressure distribution and vertical ground reaction forces were measured before and after physical exercise. The subjects first ran a given distance wearing sport shoes, had a rest and then ran the same distance barefoot. The results showed marked age related differences after exercise. The pressure values were increased in all of the youths in the middle foot region. In comparison young children always exhibited an unbound gait pattern without any dynamic foot roll during heel strike or toe-off. The forefoot had ground contact from the beginning of the stance phase. To compensate for the lack of dynamic foot roll it is recommended that children wear a shoe with a soft sole and with sufficient space for toe movement. The sports shoe for youths should grip the heel and support the longitudinal arch to prevent an incorrect weight distribution.

  16. Noninvasive Measurement of Central Vascular Pressures With Arterial Tonometry: Clinical Revival of the Pulse Pressure Waveform?

    Science.gov (United States)

    Nelson, Matthew R.; Stepanek, Jan; Cevette, Michael; Covalciuc, Michael; Hurst, R. Todd; Tajik, A. Jamil

    2010-01-01

    The arterial pulse has historically been an essential source of information in the clinical assessment of health. With current sphygmomanometric and oscillometric devices, only the peak and trough of the peripheral arterial pulse waveform are clinically used. Several limitations exist with peripheral blood pressure. First, central aortic pressure is a better predictor of cardiovascular outcome than peripheral pressure. Second, peripherally obtained blood pressure does not accurately reflect central pressure because of pressure amplification. Lastly, antihypertensive medications have differing effects on central pressures despite similar reductions in brachial blood pressure. Applanation tonometry can overcome the limitations of peripheral pressure by determining the shape of the aortic waveform from the radial artery. Waveform analysis not only indicates central systolic and diastolic pressure but also determines the influence of pulse wave reflection on the central pressure waveform. It can serve as a useful adjunct to brachial blood pressure measurements in initiating and monitoring hypertensive treatment, in observing the hemodynamic effects of atherosclerotic risk factors, and in predicting cardiovascular outcomes and events. Radial artery applanation tonometry is a noninvasive, reproducible, and affordable technology that can be used in conjunction with peripherally obtained blood pressure to guide patient management. Keywords for the PubMed search were applanation tonometry, radial artery, central pressure, cardiovascular risk, blood pressure, and arterial pulse. Articles published from January 1, 1995, to July 1, 2009, were included in the review if they measured central pressure using radial artery applanation tonometry. PMID:20435839

  17. Blood pressure and anthropometric measurements in healthy ...

    African Journals Online (AJOL)

    Institute of Child Health, University of Benin Teaching Hospital, Benin City, Nigeria ... Blood pressures were higher in private school pupils compared with public school pupils of the ... or risks of screening and treating such underlying causes of.

  18. Application backwards characteristics analysis method to dynamic response of metals under high pressure

    Directory of Open Access Journals (Sweden)

    Pan Hao

    2015-01-01

    Full Text Available Dynamic yield strength of metals/alloys depends on loading pressure and rates sensitively. With the development of laser interferometer measurement system, extracting strength information from window/free surface velocity profiles in shock and ramp loading experiments is becoming an important method to investigate materials’ dynamic response under high pressure and high strain rates. Backwards characteristics analysis method (BCAM can analyze the velocity profiles more reasonable because it accounts for bending of the incoming characteristics due to impedance mismatch between the sample and window. Synthetic analyses of reverse impact experiment and graded-density impactor loading-releasing experiment suggest that BCAM can give more accurate results including sound speed-particle velocity and yield strength at high pressure than incremental impedance matching method. We use BCAM to analyze velocity profiles of Sn in shock-release experiments and obtain its shear modulus and yield strength at different shock pressure and investigate its phase transition and dynamic unloading response.

  19. A stochastic model for the indicated pressure process and the dynamics of the internal combustion engine

    Energy Technology Data Exchange (ETDEWEB)

    Rizzoni, G. (Michigan Univ., Ann Arbor, MI (USA). Dept. of Electrical Engineering and Computer Science)

    1989-08-01

    In-cylinder gas pressure has long been recognized as a fundamental measure of performance in the internal combustion engine. Among the issues that have been the subject of research in recent years is the study of the effects cyclic combustion variability has on the cycle-to-cycle and cylinder-to-cylinder fluctuations in combustion pressures. Some of the research problems pertaining to cyclic combustion variability are to reformulate from a perspective markedly different from the fluid dynamic and thermodynamic models which traditionally characterize this research: a system viewpoint is embraced to construct a stochastic model for the indicated pressure process and the dynamics of the internal combustion engine. First a deterministic model for the dynamics of the engine is described; then a stochastic model is proposed for the cylinder pressure process. The deterministic model and the stochastic representation are then tied together in a Kalman filter model. Experimental results are discussed to validate the models.

  20. [Measurement of blood pressure variability and the clinical value].

    Science.gov (United States)

    Kékes, Ede; Kiss, István

    2014-10-19

    Authors have collected and analyzed literature data on blood pressure variability. They present the methods of blood pressure variability measurement, clinical value and relationships with target organ damages and risk of presence of cardiovascular events. They collect data about the prognostic value of blood pressure variability and the effects of different antihypertensive drugs on blood pressure variability. They underline that in addition to reduction of blood pressure to target value, it is essential to influence blood pressure fluctuation and decrease blood pressure variability, because blood pressure fluctuation presents a major threat for the hypertensive subjects. Data from national studies are also presented. They welcome that measurement of blood pressure variability has been included in international guidelines.

  1. Ionic conductivity measurements of zirconia under pressure using impedance spectroscopy

    CERN Document Server

    Takebe, H; Ohtaka, O; Fukui, H; Yoshiasa, A; Yamanaka, T; Ota, K; Kikegawa, T

    2002-01-01

    We have set up an electrical conductivity measurement system under high-pressure and high-temperature conditions with a multi-anvil high-pressure apparatus using an AC complex impedance method. With this system, we have successfully measured the electrical conductivity of stabilized ZrO sub 2 (Y sub 2 O sub 3 -ZrO sub 2 solid solution) under pressures up to 5 GPa in the temperature range from 300 to 1200 K. The electrical conductivities obtained under pressure are compatible with those of previous results measured at ambient pressure.

  2. Calibrating airborne measurements of airspeed, pressure and temperature using a Doppler laser air-motion sensor

    Directory of Open Access Journals (Sweden)

    W. A. Cooper

    2014-09-01

    Full Text Available A new laser air-motion sensor measures the true airspeed with a standard uncertainty of less than 0.1 m s−1 and so reduces uncertainty in the measured component of the relative wind along the longitudinal axis of the aircraft to about the same level. The calculated pressure expected from that airspeed at the inlet of a pitot tube then provides a basis for calibrating the measurements of dynamic and static pressure, reducing standard uncertainty in those measurements to less than 0.3 hPa and the precision applicable to steady flight conditions to about 0.1 hPa. These improved measurements of pressure, combined with high-resolution measurements of geometric altitude from the global positioning system, then indicate (via integrations of the hydrostatic equation during climbs and descents that the offset and uncertainty in temperature measurement for one research aircraft are +0.3 ± 0.3 °C. For airspeed, pressure and temperature, these are significant reductions in uncertainty vs. those obtained from calibrations using standard techniques. Finally, it is shown that although the initial calibration of the measured static and dynamic pressures requires a measured temperature, once calibrated these measured pressures and the measurement of airspeed from the new laser air-motion sensor provide a measurement of temperature that does not depend on any other temperature sensor.

  3. Modeling the pressure inactivation dynamics of Escherichia coli

    Directory of Open Access Journals (Sweden)

    Yamamoto K.

    2005-01-01

    Full Text Available Escherichia coli, as a model microorganism, was treated in phosphate-buffered saline under high hydrostatic pressure between 100 and 300 MPa, and the inactivation dynamics was investigated from the viewpoint of predictive microbiology. Inactivation data were curve fitted by typical predictive models: logistic, Gompertz and Weibull functions. Weibull function described the inactivation curve the best. Two parameters of Weibull function were calculated for each holding pressure and their dependence on holding pressure was obtained by interpolation. With the interpolated parameters, inactivation curves were simulated and compared with the experimental data sets.

  4. A Direct Two-Dimensional Pressure Formulation in Molecular Dynamics

    CERN Document Server

    YD, Sumith

    2016-01-01

    Two-dimensional (2D) pressure field estimation in molecular dynamics (MD) simulations has been done using three-dimensional (3D) pressure field calculations followed by averaging, which is computationally expensive due to 3D convolutions. In this work, we develop a direct 2D pressure field estimation method which is much faster than 3D methods without losing accuracy. The method is validated with MD simulations on two systems: a liquid film and a cylindrical drop of argon suspended in surrounding vapor.

  5. Dynamics of High Pressure Reacting Shear Flows

    Science.gov (United States)

    2015-10-02

    amplitude measurement described by Alenius (2014) • 1000-2000 sampled used Time average image subtracted from data Amplitude of mode at t = 0 Accounts for...and harmonics • Single modes can reconstruct convective processes (POD requires two modes) • Less efficient at reconstructing signal energy compared...Imaginary Receptivity mainly in the fundamental, some coherence at harmonics . DISTRIBUTION A: Approved for public release; distribution unlimited 22 Max

  6. Molecular dynamics study of helium bubble pressure in titanium

    Institute of Scientific and Technical Information of China (English)

    Zhang Bao-Ling; Wang Jun; Hou Qing

    2011-01-01

    In this paper, the pressure state of the helium bubble in titanium is simulated by a molecular dynamics (MD) method. First, the possible helium/vacancy ratio is determined according to therelation between the bubble pressure and helium/vacancy ratio; then the dependences of the helium bubble pressure on the bubble radius at different temperatures are studied. It is shown that the product of the bubble pressure and the radius is approximately a constant, a result justifying the pressure-radius relation predicted by thermodynamics-based theory for gas bubble. Furthermore, a state equation of the helium bubble is established based on the MD calculations. Comparison between the results obtained by the state equation and corresponding experimental data shows that the state equation can describe reasonably the state of helium bubble and thus could be used for Monte Carlo simulations of the evolution of helium bubble in metals.

  7. Irrigation dynamic pressure-assisted hydrodissection during cataract surgery

    Directory of Open Access Journals (Sweden)

    Masuda Y

    2017-02-01

    Full Text Available Yoichiro Masuda,1 Hisaharu Iwaki,2 Noriko Kato,1 Genichiro Takahashi,1 Kotaro Oki,3 Hiroshi Tsuneoka4 1Department of Ophthalmology, The Jikei University, Katsushika Medical Center, 2Iwaki Eye Clinic, 3Oki Eye Surgery Center, 4Department of Ophthalmology, The Jikei University, School of Medicine, Tokyo, Japan Abstract: The irrigation dynamic pressure-assisted hydrodissection technique (irrigation-hydro [iH] does not require performing manual hydrodissection using a syringe and cannula to achieve cortical-capsular cleavage during cataract surgery. Since the iH technique uses the phaco tip to intentionally vacuum the intraocular fluid in order to induce the irrigation dynamic pressure for cortical-capsular cleavage, there is a reduction in the intraocular pressure (IOP from the bottle-height-dependent hydrostatic pressure. Thus, since the peak irrigation pressure derived from the phaco tip sleeve will be limited by the height of the irrigation fluid bottle, this is advantageous in helping to avoid excessively high IOP during cortical-capsular hydrodissection. Using this technique, we were able to effectively perform phacoemulsification without complications in 607 of 609 cataract eyes. Our findings show that utilization of the iH technique would be of benefit to patients, as it prevents high-pressure hydrodissection-related complications, such as capsular block syndrome and tears in the anterior hyaloid membrane during cataract surgery. Keywords: cataract surgery, hydrodissection, irrigation pressure, hydrodissection-related complication, capsular block syndrome, anterior hyaloid membrane tear, FLACS

  8. Conversion of Dynamic High Pressures from Air to Water for a Spherical TNT Charge

    Directory of Open Access Journals (Sweden)

    A. K. Sharma

    1996-01-01

    Full Text Available A numerical method has been applied to convert the dynamic high pressures from air-to-water for a spherical TNT charge. Standard equation of scaling law in air for TNT has been utilised to make the necessary conversions. The investigations have been made by taking into consideration the ambient pressure values for the two media. The calculations have been performed under the scaled distances to get better results. Experimental measurements using indigenous blast pressure gauge have been undertaken by detonating spherical charges of TNT under the same scaled distances in water to check the correctness of results and direct application of this method. A fairly close agreement between the theoretically computed and the experimental values of the dynamic high pressures shows the practical utility of this approach in that it enables an estimate of the experimental shock wave pressures, without conducting underwater experiments.

  9. Measurement of unsteady surface pressure on rotor blades of fans by pressure-sensitive paint

    Science.gov (United States)

    Yokoyama, Hiroshi; Miura, Kouhei; Iida, Akiyoshi

    2017-01-01

    To clarify the unsteady pressure distributions on the rotor blades of an axial fan, a pressure-sensitive paint (PSP) technique was used. To capture the image of the rotating fan as a static image, an optical derotator method with a dove prism was adopted. It was confirmed by preliminary experiments with a resonator and a speaker that the pressure fluctuations with 347 Hz can be measured by the present PSP. The measured mean pressure distributions were compared with the predicted results based on large-eddy simulations. The measured instantaneous surface pressure is instrumental to identify acoustic source of fan noise in the design stage.

  10. Measurement of improved pressure dependence of superconducting transition temperature

    Science.gov (United States)

    Karmakar, S.

    2013-06-01

    We describe a technique for making electrical transport measurements in a diamond anvil cell at liquid helium temperature having in situ pressure measurement option, permitting accurate pressure determination at any low temperature during the resistance measurement scan. In general, for four-probe resistivity measurements on a polycrystalline sample, four fine gold wires are kept in contact with the sample with the help of the compression from the soft solid (usually alkali halides such as NaCl, KCl, etc.) acting as a pressure-transmitting medium. The actual pressure on the sample is underestimated if not measured from a ruby sphere placed adjacent to the sample and at that very low temperature. Here, we demonstrate the technique with a quasi-four-probe resistance measurement on an Fe-based superconductor in the temperature range 1.2-300 K and pressures up to 8 GPa to find an improved pressure dependence of the superconducting transition temperature.

  11. [Reproducibility of arterial pressure measured in the ELSA-Brasil with 24-hour pressure monitoring].

    Science.gov (United States)

    Nascimento, Larissa Rangel; Molina, Maria del Carmen Bisi; Faria, Carolina Perim; Cunha, Roberto de Sá; Mill, José Geraldo

    2013-06-01

    To determine the reproducibility of casual arterial pressure measurement and to confirm pressure diagnosis by monitoring of participants in the ELSA-Brasil (Estudo Longitudinal de Saúde do Adulto - Brazilian Longitudinal Study for Adult Health). Casual blood pressure was measured with an oscilometric device. A sub-sample of participants (N = 255) from Espírito Santo state (Southeastern Brazil) was reevaluated using the same methodology following one to ten weeks and, in addition, underwent arterial blood pressure monitoring. Diagnosis of hypertension used cut off points of 140/90 mmHg for casual pressure and 130/80 mmHg for arterial blood pressure monitoring. White coat hypertension was defined as the presence of hypertension in casual blood pressure and normal arterial blood pressure monitoring, and converse findings characterized masked hypertension. Data are from 230 participants that on the two occasions were free from antihypertensive medication (N1 = 153) or under the same antihypertensive regimen (N2 = 77). Normotension was confirmed by arterial blood pressure monitoring in 120 out of 134 participants of the N1 group. In N2, blood pressure control was confirmed by arterial blood pressure monitoring in 43 of 54 participants with controlled hypertension per casual blood pressure. Overall diagnostic concordance between casual blood pressure and arterial blood pressure monitoring was 78% (kappa = 0.44). In the N1 group, six subjects (4%) presented white coat hypertension, and 23 subjects (25%) presented with masked hypertension. Diagnostic concordance between casual blood pressure and arterial blood pressure monitoring was moderate. The rigorous standardization of casual blood pressure measurement adopted in the ELSA-Brasil study was able to reduce white coat hypertension. The high frequency of masked hypertension may suggest that pressure values obtained by arterial blood pressure monitoring indicate an elevated degree of stress at work.

  12. Experimental research on influence of emulsifier on crystallization quantity of emulsion explosives under dynamic pressure

    Institute of Scientific and Technical Information of China (English)

    HUANG Wen-yao; YAN Shi-long; WU Hong-bo; YUAN Sheng-fang

    2011-01-01

    Dynamic pressure was applied on emulsion explosive by using an underwater explosion measuring apparatus, and the crystallization quantity was measured by dissolution method after emulsion explosive was pressed; the influence of emulsi fier content and type was analyzed. The experimental results show that emulsifier content and type have an important effect on crystallization quantity of emulsion explosive. The crystallization quantity will reduce with Span-80 content from 2% to 4%, so the demulsification and crystallization will decrease if the emulsifier content improves appropriately and the dynamic pressure resistance will increase. For emulsion explosive emulsified by T-152 and Span-80, the crystallization quantity with T-152 is less than that of Span-80 under the same dynamic pressure. This shows that the emulsifying effect of T-152 is better than Span-80.

  13. Correlation of intraluminal esophageal pressure with the dynamic extension of tracheoesophageal voice in total laryngectomees

    Directory of Open Access Journals (Sweden)

    Nathália Reis

    2013-05-01

    Full Text Available PURPOSE: To evaluate and correlate the amplitude of esophageal contractions triggered by swallowing water with dynamic extension and habitual, strong and weak sound intensity in total laryngectomees wearing a tracheoesophageal prosthesis. METHODS: Thirty total laryngectomees using tracheoesophageal voice with a phonatory prosthesis were evaluated by measuring the amplitude of contractions in the proximal, middle and distal esophagus and the pressure of the pharyngoesophageal transition by manometry. In order to measure vocal intensity the subject was asked to emit phonation of the vowel /a/ at habitual, strong and weak intensity which was captured with a sound pressure meter. Dynamic extension was calculated by subtracting strong intensity from weak intensity. RESULTS: A positive correlation was observed between contraction amplitude and dynamic extension in the proximal (rho: 0.45; p=0.01 and distal (rho: 0.41; p=0.02 esophagus There was no correlation with other parameters.. Total laryngectomees wearing a phonatory prosthesis with a dynamic extension above 21 dBNPS had greater contraction amplitude than laryngectomees with a dynamic extension below this value. CONCLUSIONS: There was a positive correlation between pressure amplitude in the proximal and distal esophagus and increased dynamic extension. The individuals with normal dynamic extension had greater contraction amplitude in the proximal esophagus than individuals with dynamic extension lower than the expected values for age.

  14. Acoustic sensor for remote measuring of pressure

    Directory of Open Access Journals (Sweden)

    Kataev V. F.

    2008-04-01

    Full Text Available The paper deals with sensors based on delay lines on surface acoustic waves (SAW, having a receiving-emitting and a reflective interdigital transducers (IDT. The dependence of the reflection coefficient of SAW on type and intensity of the load was studied. The authors propose a composite delay line in which the phase of the reflection coefficient depends on the pressure. Pressure leads to a shift of the reflective IDT relative to the transceiver, because they are located on different substrates. The paper also presents functional diagrams of the interrogator.

  15. Linear servo-controlled pressure generator for forced oscillation measurements.

    Science.gov (United States)

    de Melo, P L; Werneck, M M; Giannella-Neto, A

    1998-01-01

    In respiratory input impedance measurements, the low-frequency range contains important clinical and physiological information. However, the patient's spontaneous ventilation can contaminate the data in this range, leading to unreliable results. Unbiased estimators are a good alternative to overcome this problem, provided that the generator is considered linear. This condition is not fulfilled by most existing generators as they are based on loudspeakers, which have strong nonlinearities. The present work aims to contribute to the solution of this problem, and describes a pressure generator that minimises the nonlinearities by an optical sensor placed in a position feedback loop. The static evaluation shows a high linearity for the optical system. The well known frequency response of pressure transducers is used in the dynamic evaluation of the instrument. The analysis of the generator shows that the use of position feedback improved the frequency response. The total harmonic distortion (THD) measurement shows that closed loop resulted in an effective decrease in the nonlinearities. The reduction of THD achieved by the servo-controlled generator can contribute to the practical implementation of the unbiased estimators, increasing the reliability of the impedance data, especially in the low-frequency range. This system is compared with conventional generators and with another servo-controlled system.

  16. Compressibility measurements of gases using externally heated pressure vessels.

    Science.gov (United States)

    Presnall, D. C.

    1971-01-01

    Most of the data collected under conditions of high temperature and pressure have been determined using a thick-walled bomb of carefully measured and fixed volume which is externally heated by an electric furnace or a thermostatically controlled bath. There are numerous variations on the basic method depending on the pressure-temperature range of interest, and the particular gas or gas mixture being studied. The construction and calibration of the apparatus is discussed, giving attention to the pressure vessel, the volume of the bomb, the measurement of pressure, the control and measurement of temperature, and the measurement of the amount and composition of gas in the bomb.

  17. Two methods for absolute calibration of dynamic pressure transducers

    Science.gov (United States)

    Swift, G. W.; Migliori, A.; Garrett, S. L.; Wheatley, J. C.

    1982-12-01

    Two techniques are described for absolute calibration of a dynamic pressure transducer from 0 to 400 Hz in 1-MPa helium gas. One technique is based on a comparison to a mercury manometer; the other is based on the principle of reciprocity. The two techniques agree within the instrumental uncertainties of 1%.

  18. Blood pressure measurement: lessons learned from our ancestors.

    Science.gov (United States)

    Karamanou, Marianna; Papaioannou, Theodore G; Tsoucalas, Gregory; Tousoulis, Dimitris; Stefanadis, Christodoulos; Androutsos, George

    2015-01-01

    The profound observations of William Harvey (1578-1657), in blood circulation and the progress of physical science laid the foundation for the development of the Iatrophysical School that contributed to the evolution of clinical sphygmomanometry. The pioneer work of Reverend Stephen Hales (1677-1761) demonstrated the dynamics of the vascular system. One century later the French physician Jean-Léonard-Marie Poiseuille (1797-1867) invented a U-tube mercury manometer and in 1860 the physiologist Etienne- Jules Marey (1830-1904) devised the first portable sphygmograph for recording the pulse wave. The non-invasive techniques of blood pressure measurement were completed by Scipione Riva-Rocci (1896-1937) sphygmomanometer and the description of "Korotkov sounds" by the Russian surgeon Nikolai- Sergeyevich Korotkov (1874-1920).

  19. Pressure and Magnetics Measurements of Single and Merged Jets

    Science.gov (United States)

    Messer, S.; Case, A.; Brockington, S.; Bomgardner, R.; Witherspoon, F. D.

    2010-11-01

    We present pressure and magnetic data from both a single full scale coaxial gun and from the merging of jets from several minirailguns. The magnetic probes measure all three components of field, and include an array of probes inside the coaxial gun. Magnetic measurements beyond the muzzle of the gun show the scale of currents trapped in the plasma plume. The pressure probe measures adiabatic stagnation pressure and shows how this quantity decreases with distance from the gun as well as the changes in stagnation pressure through the merge process. Stagnation pressure is influenced by density, temperature, and velocity, and serves as a check on spectroscopic and interferometer measurements. Unlike optical measurements, stagnation pressure is taken at a definite location. These guns are early prototypes of guns to be installed on the Plasma Liner eXperiment at LANL. The jet-merging results are reviewed in the context of what is expected for PLX.

  20. Validation of an Endoscopic Fibre-Optic Pressure Sensor for Noninvasive Measurement of Variceal Pressure

    Directory of Open Access Journals (Sweden)

    Bin Sun

    2016-01-01

    Full Text Available In this study, the authors have developed endoscopic fibre-optic pressure sensor to detect variceal pressure and presented the validation of in vivo and in vitro studies, because the HVPG requires catheterization of hepatic veins, which is invasive and inconvenient. Compared with HVPG, it is better to measure directly the variceal pressure without puncturing the varices in a noninvasive way.

  1. Richtmyer-Meshkov unstable dynamics influenced by pressure fluctuations

    Science.gov (United States)

    Bhowmick, A. K.; Abarzhi, S. I.

    2016-11-01

    We theoretically study the effect of pressure fluctuations on the Richtmyer-Meshkov (RM) unstable interface in approximation of ideal incompressible immiscible fluids and two-dimensional flow. Pressure fluctuations are treated as an effective acceleration directed from the heavy to light fluid with inverse square time dependence. The group theory approach is applied to analyze large-scale coherent dynamics, solve the complete set of the governing equations, and find regular asymptotic solutions describing RM bubbles. A strong effect is found, for the first time to our knowledge, of pressure fluctuations on the interface morphology and dynamics. In the linear regime, a nearly flat bubble gets more curved, and its velocity increases for strong pressure fluctuations and decreases otherwise. In the nonlinear regime, solutions form a one-parameter family parameterized by the bubble front curvature. For the fastest stable solution in the family, the RM bubble is curved for strong pressure fluctuations and is flattened otherwise. The flow is characterized by the intense motion of the fluids in the vicinity of the interface, effectively no motion away from the interface, and presence of shear at the interface leading to formation of smaller scale vortical structures. Our theoretical results agree with and explain existing experiments and simulations and identify new qualitative and quantitative characteristics to evaluate the strength of pressure fluctuations in experiments and simulations.

  2. Tyre pressure monitoring using a dynamical model-based estimator

    Science.gov (United States)

    Reina, Giulio; Gentile, Angelo; Messina, Arcangelo

    2015-04-01

    In the last few years, various control systems have been investigated in the automotive field with the aim of increasing the level of safety and stability, avoid roll-over, and customise handling characteristics. One critical issue connected with their integration is the lack of state and parameter information. As an example, vehicle handling depends to a large extent on tyre inflation pressure. When inflation pressure drops, handling and comfort performance generally deteriorate. In addition, it results in an increase in fuel consumption and in a decrease in lifetime. Therefore, it is important to keep tyres within the normal inflation pressure range. This paper introduces a model-based approach to estimate online tyre inflation pressure. First, basic vertical dynamic modelling of the vehicle is discussed. Then, a parameter estimation framework for dynamic analysis is presented. Several important vehicle parameters including tyre inflation pressure can be estimated using the estimated states. This method aims to work during normal driving using information from standard sensors only. On the one hand, the driver is informed about the inflation pressure and he is warned for sudden changes. On the other hand, accurate estimation of the vehicle states is available as possible input to onboard control systems.

  3. Computational Fluid Dynamics Analysis of High Injection Pressure Blended Biodiesel

    Science.gov (United States)

    Khalid, Amir; Jaat, Norrizam; Faisal Hushim, Mohd; Manshoor, Bukhari; Zaman, Izzuddin; Sapit, Azwan; Razali, Azahari

    2017-08-01

    Biodiesel have great potential for substitution with petrol fuel for the purpose of achieving clean energy production and emission reduction. Among the methods that can control the combustion properties, controlling of the fuel injection conditions is one of the successful methods. The purpose of this study is to investigate the effect of high injection pressure of biodiesel blends on spray characteristics using Computational Fluid Dynamics (CFD). Injection pressure was observed at 220 MPa, 250 MPa and 280 MPa. The ambient temperature was kept held at 1050 K and ambient pressure 8 MPa in order to simulate the effect of boost pressure or turbo charger during combustion process. Computational Fluid Dynamics were used to investigate the spray characteristics of biodiesel blends such as spray penetration length, spray angle and mixture formation of fuel-air mixing. The results shows that increases of injection pressure, wider spray angle is produced by biodiesel blends and diesel fuel. The injection pressure strongly affects the mixture formation, characteristics of fuel spray, longer spray penetration length thus promotes the fuel and air mixing.

  4. Irrigation dynamic pressure-assisted hydrodissection during cataract surgery.

    Science.gov (United States)

    Masuda, Yoichiro; Iwaki, Hisaharu; Kato, Noriko; Takahashi, Genichiro; Oki, Kotaro; Tsuneoka, Hiroshi

    2017-01-01

    The irrigation dynamic pressure-assisted hydrodissection technique (irrigation-hydro [iH]) does not require performing manual hydrodissection using a syringe and cannula to achieve cortical-capsular cleavage during cataract surgery. Since the iH technique uses the phaco tip to intentionally vacuum the intraocular fluid in order to induce the irrigation dynamic pressure for cortical-capsular cleavage, there is a reduction in the intraocular pressure (IOP) from the bottle-height-dependent hydrostatic pressure. Thus, since the peak irrigation pressure derived from the phaco tip sleeve will be limited by the height of the irrigation fluid bottle, this is advantageous in helping to avoid excessively high IOP during cortical-capsular hydrodissection. Using this technique, we were able to effectively perform phacoemulsification without complications in 607 of 609 cataract eyes. Our findings show that utilization of the iH technique would be of benefit to patients, as it prevents high-pressure hydrodissection-related complications, such as capsular block syndrome and tears in the anterior hyaloid membrane during cataract surgery.

  5. Irrigation dynamic pressure-assisted hydrodissection during cataract surgery

    Science.gov (United States)

    Masuda, Yoichiro; Iwaki, Hisaharu; Kato, Noriko; Takahashi, Genichiro; Oki, Kotaro; Tsuneoka, Hiroshi

    2017-01-01

    The irrigation dynamic pressure-assisted hydrodissection technique (irrigation-hydro [iH]) does not require performing manual hydrodissection using a syringe and cannula to achieve cortical-capsular cleavage during cataract surgery. Since the iH technique uses the phaco tip to intentionally vacuum the intraocular fluid in order to induce the irrigation dynamic pressure for cortical-capsular cleavage, there is a reduction in the intraocular pressure (IOP) from the bottle-height-dependent hydrostatic pressure. Thus, since the peak irrigation pressure derived from the phaco tip sleeve will be limited by the height of the irrigation fluid bottle, this is advantageous in helping to avoid excessively high IOP during cortical-capsular hydrodissection. Using this technique, we were able to effectively perform phacoemulsification without complications in 607 of 609 cataract eyes. Our findings show that utilization of the iH technique would be of benefit to patients, as it prevents high-pressure hydrodissection-related complications, such as capsular block syndrome and tears in the anterior hyaloid membrane during cataract surgery. PMID:28243054

  6. Reliability of blood pressure measurement and cardiovascular risk prediction

    OpenAIRE

    van der Hoeven, N.V.

    2016-01-01

    High blood pressure is one of the leading risk factors for cardiovascular disease, but difficult to reliably assess because there are many factors which can influence blood pressure including stress, exercise or illness. The first part of this thesis focuses on possible ways to improve the reliability of blood pressure measurement for proper cardiovascular risk prediction, both in and out of the doctor’s office. We show that it is possible to obtain a reliable blood pressure without the use o...

  7. A method enabling simultaneous pressure and temperature measurement using a single piezoresistive MEMS pressure sensor

    Science.gov (United States)

    Frantlović, Miloš; Jokić, Ivana; Lazić, Žarko; Smiljanić, Milče; Obradov, Marko; Vukelić, Branko; Jakšić, Zoran; Stanković, Srđan

    2016-12-01

    In this paper we present a high-performance, simple and low-cost method for simultaneous measurement of pressure and temperature using a single piezoresistive MEMS pressure sensor. The proposed measurement method utilizes the parasitic temperature sensitivity of the sensing element for both pressure measurement correction and temperature measurement. A parametric mathematical model of the sensor was established and its parameters were calculated using the obtained characterization data. Based on the model, a real-time sensor correction for both pressure and temperature measurements was implemented in a target measurement system. The proposed method was verified experimentally on a group of typical industrial-grade piezoresistive sensors. The obtained results indicate that the method enables the pressure measurement performance to exceed that of typical digital industrial pressure transmitters, achieving at the same time the temperature measurement performance comparable to industrial-grade platinum resistance temperature sensors. The presented work is directly applicable in industrial instrumentation, where it can add temperature measurement capability to the existing pressure measurement instruments, requiring little or no additional hardware, and without adverse effects on pressure measurement performance.

  8. Embedded optical probes for simultaneous pressure and temperature measurement of materials in extreme conditions

    Science.gov (United States)

    Sandberg, R. L.; Rodriguez, G.; Gibson, L. L.; Dattelbaum, D. M.; Stevens, G. D.; Grover, M.; Lalone, B. M.; Udd, E.

    2014-05-01

    We present recent efforts at Los Alamos National Laboratory (LANL) to develop sensors for simultaneous, in situ pressure and temperature measurements under dynamic conditions by using an all-optical fiber-based approach. While similar tests have been done previously in deflagration-to-detonation tests (DDT), where pressure and temperature were measured to 82 kbar and 400°C simultaneously, here we demonstrate the use of embedded fiber grating sensors to obtain high temporal resolution, in situ pressure measurements in inert materials. We present two experimental demonstrations of pressure measurements: (1) under precise shock loading from a gas-gun driven plate impact and (2) under high explosive driven shock in a water filled vessel. The system capitalizes on existing telecom components and fast transient digitizing recording technology. It operates as a relatively inexpensive embedded probe (single-mode 1550 nm fiber-based Bragg grating) that provides a continuous fast pressure record during shock and/or detonation. By applying well-controlled shock wave pressure profiles to these inert materials, we study the dynamic pressure response of embedded fiber Bragg gratings to extract pressure amplitude of the shock wave and compare our results with particle velocity wave profiles measured simultaneously.

  9. Design and Development of a Pressure Transducer for High Hydrostatic Pressure Measurements up to 200 MPa

    Science.gov (United States)

    Kumar, Anuj; Yadav, Sanjay; Agarwal, Ravinder

    2016-06-01

    A number of pressure transducers, based on strain gauge, capacitance/inductance type, frequency resonators, are commercially available and are being used for sensing and producing an electrical output proportional to applied pressure. These sensors have their own advantages and limitations due to operational ease, measurement uncertainty and the costs. Strain gauge type transducers are now well established devices for accurate and precise measurement of pressure within measurement uncertainty up to 0.1 % of full scale. In the present research work, an indigenous strain gauge pressure transducer has been designed, developed, tested and calibrated for pressure measurement up to 200 MPa. The measurement uncertainty estimated using the pressure transducer was found better than 0.1 % of full scale. This transducer was developed using four foil type strain gauges, bonded, two in axial direction while other two in radial direction, to the controlled stress zones of a tubular maraging steel active cylinder working also as diaphragm. The strain gages were then connected to a Wheatstone bridge arrangement to measure stress generated strains. The pressure was applied through matching connector designed in the same tubular transducer active element. The threaded unique design in a single piece through collar, ferule and tubing arrangement provides leak proof pressure connections with external devices without using additional seals. The calibration and performance checking of the pressure transducer was carried out using dead weight type national pressure standard using the internationally accepted calibration procedure.

  10. Design and Development of a Pressure Transducer for High Hydrostatic Pressure Measurements up to 200 MPa

    Science.gov (United States)

    Kumar, Anuj; Yadav, Sanjay; Agarwal, Ravinder

    2017-08-01

    A number of pressure transducers, based on strain gauge, capacitance/inductance type, frequency resonators, are commercially available and are being used for sensing and producing an electrical output proportional to applied pressure. These sensors have their own advantages and limitations due to operational ease, measurement uncertainty and the costs. Strain gauge type transducers are now well established devices for accurate and precise measurement of pressure within measurement uncertainty up to 0.1 % of full scale. In the present research work, an indigenous strain gauge pressure transducer has been designed, developed, tested and calibrated for pressure measurement up to 200 MPa. The measurement uncertainty estimated using the pressure transducer was found better than 0.1 % of full scale. This transducer was developed using four foil type strain gauges, bonded, two in axial direction while other two in radial direction, to the controlled stress zones of a tubular maraging steel active cylinder working also as diaphragm. The strain gages were then connected to a Wheatstone bridge arrangement to measure stress generated strains. The pressure was applied through matching connector designed in the same tubular transducer active element. The threaded unique design in a single piece through collar, ferule and tubing arrangement provides leak proof pressure connections with external devices without using additional seals. The calibration and performance checking of the pressure transducer was carried out using dead weight type national pressure standard using the internationally accepted calibration procedure.

  11. High Speed Pressure Sensitive Paint for Dynamic Testing

    Science.gov (United States)

    Pena, Carolina; Chism, Kyle; Hubner, Paul

    2016-11-01

    Pressure sensitive paint (PSP) allows engineers to obtain accurate, high-spatial-resolution measurements of pressure fields over a structure. The pressure is directly related to the luminescence emitted by the paint due to oxygen quenching. Fast PSP has a higher surface area due to its porosity compared to conventional PSP, which enables faster diffusion and measurements to be acquired three orders of magnitude faster than with conventional PSP. A fast time response is needed when testing vibrating structures due to fluid-structure interaction. The goal of this summer project was to set-up, test and analyze the pressure field of an impinging air jet on a vibrating cantilever beam using Fast PSP. Software routines were developed for the processing of the emission images, videos of a static beam coated with Fast PSP were acquired with the air jet on and off, and the intensities of these two cases were ratioed and calibrated to pressure. Going forward, unsteady pressures on a vibrating beam will be measured and presented. Eventually, the long-term goal is to integrate luminescent pressure and strain measurement techniques, simultaneously using Fast PSP and a luminescent photoelastic coating on vibrating structures. Funding from NSF REU site Grant EEC 1358991 is greatly appreciated.

  12. Dynamic effects of high-pressure pulsed water jet in low-permeability coal seams

    Institute of Scientific and Technical Information of China (English)

    LI Xiao-hong; ZHOU Dong-ping; LU Yi-yu; KANG Yong; ZHAO Yu; WANG Xiao-chuan

    2009-01-01

    Mine gas extraction in China is difficult due to the characteristics such as mi-cro-porosity, low-permeability and high adsorption of coal seams. The pulsed mechanism of a high-pressure pulsed water jet was studied through theoretical analysis, experiment and field measurement. The results show that high-pressure pulsed water jet has three dynamic properties. What's more, the three dynamic effects can be found in low-perme-ability coal seams. A new pulsed water jet with 200-1 000 Hz oscillation frequency and peak pressure 2.5 times than average pressure was introduced. During bubble collapsing, sound vibration and instantaneous high pressures over 100 MPa enhanced the cutting ability of the high-pressure jet. Through high-pressure pulsed water jet drilling and slotting, the exposure area of coal bodies was greatly enlarged and pressure of the coal seams rapidly decreased. Therefore, the permeability of coal seams was improved and gas ab-sorption rate also decreased. Application results show that gas adsorption rate decreased by 30%-40% and the penetrability coefficient increased 100 times. This proves that high-pressure pulsed water is more efficient than other conventional methods.

  13. A blood pressure measurement method based on synergetics theory

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    <正>The principle for blood pressure measurement using pulse transit time is introduced in this paper.And the math model of synergetics theory is studied in detail.The synergetics theory is applied in the analysis of blood pressure measurement data.The simulation results show that the application of synergetics theory is helpful to judge the normal blood pressure,and the accuracy is up to 80%.

  14. Identification of an average temperature and a dynamical pressure in a multitemperature mixture of fluids.

    Science.gov (United States)

    Gouin, Henri; Ruggeri, Tommaso

    2008-07-01

    We present a classical approach to a mixture of compressible fluids when each constituent has its own temperature. The introduction of an average temperature together with the entropy principle dictates the classical Fick law for diffusion and also novel constitutive equations associated with the difference of temperatures between the components. The constitutive equations fit with results recently obtained through a Maxwellian iteration procedure in extended thermodynamics theory of multitemperature mixtures. The differences of temperatures between the constituents imply the existence of a dynamical pressure even if the fluids have a zero bulk viscosity. The nonequilibrium dynamical pressure can be measured and may be convenient in several physical situations, such as, for example, in cosmological circumstances where--as many authors assert--a dynamical pressure played a major role in the evolution of the early universe.

  15. Modern gas-based temperature and pressure measurements

    CERN Document Server

    Pavese, Franco

    2013-01-01

    This 2nd edition volume of Modern Gas-Based Temperature and Pressure Measurements follows the first publication in 1992. It collects a much larger set of information, reference data, and bibliography in temperature and pressure metrology of gaseous substances, including the physical-chemical issues related to gaseous substances. The book provides solutions to practical applications where gases are used in different thermodynamic conditions. Modern Gas-Based Temperature and Pressure Measurements, 2nd edition is the only comprehensive survey of methods for pressure measurement in gaseous media used in the medium-to-low pressure range closely connected with thermometry. It assembles current information on thermometry and manometry that involve the use of gaseous substances which are likely to be valid methods for the future. As such, it is an important resource for the researcher. This edition is updated through the very latest scientific and technical developments of gas-based temperature and pressure measurem...

  16. [Mobile phone platform for wireless monitoring of human dynamic plantar pressure].

    Science.gov (United States)

    Wang, Hao; Han, Meng; Liu, Jing

    2010-11-01

    This paper constructed a plantar pressure sensing system based on Bluetooth communication of mobile phone with embedded Windows Mobile system. With the MCU (Microprocessor Control Unit) and Bluetooth module, the pressure sensor and the data acquisition circuit was designed and integrated, with software developed under Visual Studio 2008 environment. The real-time monitoring of human dynamic plantar pressure signal, and transferring, displaying and storing the recorded data on a mobile phone were achieved. This method offers an important measure to acquire human gait information via a pervasive and low cost way.

  17. Measuring elevated intracranial pressure through noninvasive methods

    DEFF Research Database (Denmark)

    Kristiansson, Helena; Nissborg, Emelie; Bartek, Jiri;

    2013-01-01

    . This article is a review of the current literature on noninvasive methods for measuring and evaluating elevated ICP. The main focus is on studies that compare noninvasively measured ICP with invasively measured ICP. The aim is to provide an overview of the current state of the most common noninvasive...... is associated with certain risks. Intraparenchymal ICP monitoring methods are considered to be a safer alternative but can, in certain conditions, be imprecise due to zero drift and still require an invasive procedure. An accurate noninvasive method to measure elevated ICP would therefore be desirable...

  18. Dynamic damper pressure fluctuation in the pumping systems

    Directory of Open Access Journals (Sweden)

    O.V. Korolyov

    2016-05-01

    Full Text Available Inertial part of any devices and equipment (e.g., pumps, hung or mounted on the resilient frame and being under the influence of the disturbing force that works at a constant frequency, may be subject to fluctuations, especially near of the resonance area. For elimination these fluctuations, you can resort to the use of a dynamic damper. Aim: The aim of the work is an analytical study of various dynamic dampers to reduce pressure fluctuation problems in pumping systems. Materials and Methods: A comparative analysis of efficiency of functioning was carried out for two types of dynamic dampers - hydraulic and mechanical. Results: The technique for calculating of dynamic damper of fluid pressure fluctuations in the hydraulic and mechanical pumps is presented. Algorithms of calculations are reported to engineering applications and implemented in the production process. The calculations show that the use of dynamic mechanical dampers is expedient at high frequency pumps, and, with increasing frequency of the pump by 6 times, winning in the dimensions of the damper in 3.5 times.

  19. DYNAMICAL BEHAVIOR OF VISCOELASTIC CYLINDRICAL SHELLS UNDER AXIAL PRESSURES

    Institute of Scientific and Technical Information of China (English)

    程昌钧; 张能辉

    2001-01-01

    The hypotheses of the Kármán-Donnell theory of thin shells with large deflections and the Boltzmann laws for isotropic linear, viscoelastic materials, the constitutive equations of shallow shells are first derived. Then the governing equations for the deflection equations of elastic thin plates. Introducing proper assumptions, an approximate theory for viscoelastic cylindrical shells under axial pressures can be obtained. Finally, the dynamical behavior is studied in detail by using several numerical methods. Dynamical properties,such as, hyperchaos , chaos, strange attractor, limit cycle etc., are discovered.

  20. Pressure effects on dynamics behavior of multiwall boron nitride nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Talebian, Taha [Faculty of Engineering, Neyshabur Branch, Islamic Azad University, Neyshabur (Iran, Islamic Republic of)

    2016-01-15

    The dynamic behavior of Multiwall boron nitride nanotubes (MWBNNTs) is investigated by employing multiple elastic shells model. The influences of van der Waals interactions on layers are shown as nonlinear functions of the interlayer distance of MWBNNTs. Governing equations are solved by using the developed finite element method and by employing time history diagrams. The radial wave speed from the outermost layer to the innermost layer is computed. The effects of geometrical factors such as diameter-to-thickness ratio on dynamic behavior of MWBNNTs are determined. The magnification aspects of MWBNNTs are computed, and the effects of surrounding pressures on wave speed and magnification aspect of MWBNNTs are discussed.

  1. Analysis of dynamic foot pressure distribution and ground reaction forces

    Science.gov (United States)

    Ong, F. R.; Wong, T. S.

    2005-04-01

    The purpose of this study was to assess the relationship between forces derived from in-shoe pressure distribution and GRFs during normal gait. The relationship served to demonstrate the accuracy and reliability of the in-shoe pressure sensor. The in-shoe pressure distribution from Tekscan F-Scan system outputs vertical forces and Centre of Force (COF), while the Kistler force plate gives ground reaction forces (GRFs) in terms of Fz, Fx and Fy, as well as vertical torque, Tz. The two systems were synchronized for pressure and GRFs measurements. Data was collected from four volunteers through three trials for both left and right foot under barefoot condition with the in-shoe sensor. The forces derived from pressure distribution correlated well with the vertical GRFs, and the correlation coefficient (r2) was in the range of 0.93 to 0.99. This is a result of extended calibration, which improves pressure measurement to give better accuracy and reliability. The COF from in-shoe sensor generally matched well with the force plate COP. As for the maximum vertical torque at the forefoot during toe-off, there was no relationship with the pressure distribution. However, the maximum torque was shown to give an indication of the rotational angle of the foot.

  2. Blood pressure self-measurement in the obstetric waiting room

    DEFF Research Database (Denmark)

    Wagner, Stefan; Kamper, Christina H.; Toftegaard, Thomas Skjødeberg

    2013-01-01

    a reliable blood pressure reading. Results: We found that the patients did not adhere to given instructions when performing blood pressure self-measurement in the waiting room. None of the 81 patients adhered to all six inves- tigated recommendations, while around a quarter adhered to five out of six......Background: Pregnant diabetic patients are often required to self- measure their blood pressure in the waiting room before consulta- tion. Currently used blood pressure devices do not guarantee valid measurements when used unsupervised. This could lead to misdi- agnosis and treatment error. The aim...... of this study was to investigate current use of blood pressure self-measurement in the waiting room in order to identify challenges that could influence the resulting data quality. Also, we wanted to investigate the potential for addressing these challenges with e-health and telemedicine technology. Subjects...

  3. High-pressure dynamics of hydrated protein in bioprotective trehalose environment

    Science.gov (United States)

    Diallo, S. O.; Zhang, Q.; O'Neill, H.; Mamontov, E.

    2014-10-01

    We present a pressure-dependence study of the dynamics of lysozyme protein powder immersed in deuterated α ,α -trehalose environment via quasielastic neutron scattering (QENS). The goal is to assess the baroprotective benefits of trehalose on biomolecules by comparing the findings with those of a trehalose-free reference study. While the mean-square displacement of the trehalose-free protein (hydrated to dD2O≃ 40 w%) as a whole, is reduced by increasing pressure, the actual observable relaxation dynamics in the picoseconds to nanoseconds time range remains largely unaffected by pressure—up to the maximum investigated pressure of 2.78(2) Kbar. Our observation is independent of whether or not the protein is mixed with the deuterated sugar. This suggests that the hydrated protein's conformational states at atmospheric pressure remain unaltered by hydrostatic pressures, below 2.78 Kbar. We also found the QENS response to be totally recoverable after ambient pressure conditions are restored. Small-angle neutron diffraction measurements confirm that the protein-protein correlation remains undisturbed. We observe, however, a clear narrowing of the QENS response as the temperature is decreased from 290 to 230 K in both cases, which we parametrize using the Kohlrausch-Williams-Watts stretched exponential model. Only the fraction of protons that are immobile on the accessible time window of the instrument, referred to as the elastic incoherent structure factor, is observably sensitive to pressure, increasing only marginally but systematically with increasing pressure.

  4. High pressure differential conductance measurements of (Pb,Sn)Se

    Science.gov (United States)

    Paul, Tiffany; Vangennep, Derrick; Jackson, Daniel; Biswas, Amlan; Hamlin, James

    Topological transitions have been recognized as a new type of quantum phase transition. Recently, a number of papers have reported scanning tunneling microscope (STM) measurements of the Landau level spectra of topologically non-trivial materials. Such measurements can offer substantial insight into the nature of the transition between topologically distinct phases. Although applied pressure represents an attractive means to drive a topological quantum phase transition, STM measurements can not be performed under high pressure conditions. In this talk, I will discuss our recent attempts to observe Landau level spectra in compressed (Pb,Sn)Se using differential conductance measurements. Acknowledgements: TAP supported by REU NSF DMR-1461019. Pressure cell development and measurements at high magnetic fields supported by the National High Magnetic Field Laboratory User Collaboration Grants Program. Synthesis, characterization, and high pressure measurements supported by NSF DMR-1453752.

  5. Combined NMR moisture, temperature and pressure measurements during heating

    Directory of Open Access Journals (Sweden)

    Pel L.

    2013-09-01

    Full Text Available For model validation, quantitative measurements of the evolution of moisture, temperature, and pressure distributions in time are needed. For this purpose, we have developed an NMR setup to measure the moisture transport in heated building materials. The measured combined moisture content and temperature profiles give a unique insight in the moisture transport and dehydration kinetics inside concrete during fire. These measurements give the first quantitative proof for the build-up of a moisture peak due to the vapor pressure build-up. In this study we have also combined for the first time the measurement of the moisture and temperature profiles with the measurement of the pressure at one position, which show that the pressure build up is directly related to the moisture profiles.

  6. Subharmonic contrast microbubble signals for noninvasive pressure estimation under static and dynamic flow conditions.

    Science.gov (United States)

    Halldorsdottir, Valgerdur G; Dave, Jaydev K; Leodore, Lauren M; Eisenbrey, John R; Park, Suhyun; Hall, Anne L; Thomenius, Kai; Forsberg, Flemming

    2011-07-01

    Our group has proposed the concept of subharmonic aided pressure estimation (SHAPE) utilizing microbubble-based ultrasound contrast agent signals for the noninvasive estimation of hydrostatic blood pressures. An experimental system for in vitro SHAPE was constructed based on two single-element transducers assembled confocally at a 60 degree angle to each other. Changes in the first, second and subharmonic amplitudes of five different ultrasound contrast agents were measured in vitro at static hydrostatic pressures from 0-186 mmHg, acoustic pressures from 0.35-0.60 MPa peak-to-peak and frequencies of 2.5-6.6 MHz. The most sensitive agent and optimal parameters for SHAPE were determined using linear regression analysis and implemented on a Logiq 9 scanner (GE Healthcare, Milwaukee, WI). This implementation of SHAPE was then tested under dynamic-flow conditions and compared to pressure-catheter measurements. Over the pressure range studied, the first and second harmonic amplitudes reduced approximately 2 dB for all contrast agents. Over the same pressure range, the subharmonic amplitudes decreased by 9-14 dB and excellent linear regressions were achieved with the hydrostatic pressure variations (r = 0.98, p scanner was modified to implement SHAPE on a convex transducer with a frequency range from 1.5-4.5 MHz and acoustic pressures from 0-3.34 MPa. Results matched the pressure catheter (r2 = 0.87). In conclusion, subharmonic contrast signals are a good indicator of hydrostatic pressure. Out of the five ultrasound contrast agents tested, Sonazoid was the most sensitive for subharmonic pressure estimation. Real-time SHAPE has been implemented on a commercial scanner and offers the possibility of allowing pressures in the heart and elsewhere to be obtained noninvasively.

  7. Brain tissue pressure measurements in perinatal and adult rabbits.

    Science.gov (United States)

    Hornig, G W; Lorenzo, A V; Zavala, L M; Welch, K

    1987-12-01

    Brain tissue pressure (BTP) in pre- and post-natal anesthetized rabbits, held in a stereotactic head holder, was measured with a fluid filled 23 gauge open-ended cannula connected distally to a pressure transducer. By advancing the cannula step wise through a hole in the cranium it was possible to sequentially measure pressure from the cranial subarachnoid space, cortex, ventricle and basal ganglia. Separate cannulas and transducers were used to measure CSFP from the cisterna magna and arterial and/or venous pressure. Pressure recordings obtained when the tip of the BTP cannula was located in the cranial subarachnoid space or ventricle exhibited respiratory and blood pressure pulsations equivalent to and in phase with CSF pulsations recorded from the cisterna magna. When the tip was advanced into brain parenchymal sites such pulsations were suppressed or non-detectable unless communication with a CSF compartment had been established inadvertently. Although CSF pressures in the three spinal fluid compartments were equivalent, in most animals BTP was higher than CSFP. However, after momentary venting of the system BTP equilibrated at a pressure below that of CSFP. We speculate that venting of the low compliance system (1.20 x 10(-5) ml/mmHg) relieves the isometric pressure build-up due to insertion of the cannula into brain parenchyma. Under these conditions, and at all ages examined, BTP in the rabbit is consistently lower than CSFP and, as with CSFP, it increases as the animal matures.

  8. TREATMENT OF HYPERTENSION USING TELEMEDICAL HOME BLOOD PRESSURE MEASUREMENTS

    DEFF Research Database (Denmark)

    Hoffmann-Petersen, N; Lauritzen, T; Bech, J N

    2015-01-01

    of the measurements and subsequent communication by telephone or E-mail. In the control group, patients received usual care. Primary outcome was reduction in daytime ambulatory blood pressure measurements (ABPM) from baseline to 3 months' follow-up. RESULTS: In both groups, daytime ABPM decreased significantly....../181), p = 0.34. Blood pressure reduction in the TBPM group varied with the different practices. CONCLUSIONS: No further reduction in ABPM or number of patients reaching blood pressure targets was observed when electronic transmission of TBPM was applied in the treatment of hypertension by GPs. Thus......OBJECTIVE: Telemonitoring of home blood pressure measurements (TBPM) is a new and promising supplement to diagnosis, control and treatment of hypertension. We wanted to compare the outcome of antihypertensive treatment based on TBPM and conventional monitoring of blood pressure. DESIGN AND METHOD...

  9. Pico gauges for minimally invasive intracellular hydrostatic pressure measurements

    DEFF Research Database (Denmark)

    Knoblauch, Jan; Mullendore, Daniel L.; Jensen, Kaare Hartvig

    2014-01-01

    in the tip of microcapillaries, which we call pico gauges. The production of pico gauges can be accomplished with standard laboratory equipment, and measurements are comparably easy to conduct. Example pressure measurements are performed on cells that are difficult or impossible to measure with other methods.......Intracellular pressure has a multitude of functions in cells surrounded by a cell wall or similar matrix in all kingdoms of life. The functions include cell growth, nastic movements, and penetration of tissue by parasites. The precise measurement of intracellular pressure in the majority of cells......, however, remains difficult or impossible due to their small size and/or sensitivity to manipulation. Here, we report on a method that allows precise measurements in basically any cell type over all ranges of pressure. It is based on the compression of nanoliter and picoliter volumes of oil entrapped...

  10. Pico gauges for minimally invasive intracellular hydrostatic pressure measurements.

    Science.gov (United States)

    Knoblauch, Jan; Mullendore, Daniel L; Jensen, Kaare H; Knoblauch, Michael

    2014-11-01

    Intracellular pressure has a multitude of functions in cells surrounded by a cell wall or similar matrix in all kingdoms of life. The functions include cell growth, nastic movements, and penetration of tissue by parasites. The precise measurement of intracellular pressure in the majority of cells, however, remains difficult or impossible due to their small size and/or sensitivity to manipulation. Here, we report on a method that allows precise measurements in basically any cell type over all ranges of pressure. It is based on the compression of nanoliter and picoliter volumes of oil entrapped in the tip of microcapillaries, which we call pico gauges. The production of pico gauges can be accomplished with standard laboratory equipment, and measurements are comparably easy to conduct. Example pressure measurements are performed on cells that are difficult or impossible to measure with other methods.

  11. Dynamic Inertia Measurement Method Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Critically important inertia measurements are complex and expensive to obtain due to the extensive fixturing and custom instrumentation of conventional...

  12. Irrigation dynamics associated with positive pressure, apical negative pressure and passive ultrasonic irrigations: a computational fluid dynamics analysis.

    Science.gov (United States)

    Chen, José Enrique; Nurbakhsh, Babak; Layton, Gillian; Bussmann, Markus; Kishen, Anil

    2014-08-01

    Complexities in root canal anatomy and surface adherent biofilm structures remain as challenges in endodontic disinfection. The ability of an irrigant to penetrate into the apical region of a canal, along with its interaction with the root canal walls, will aid in endodontic disinfection. The aim of this study was to qualitatively examine the irrigation dynamics of syringe irrigation with different needle tip designs (open-ended and closed-ended), apical negative pressure irrigation with the EndoVac® system, and passive ultrasonic-assisted irrigation, using a computational fluid dynamics model. Syringe-based irrigation with a side-vented needle showed a higher wall shear stress than the open-ended but was localised to a small region of the canal wall. The apical negative pressure mode of irrigation generated the lowest wall shear stress, while the passive-ultrasonic irrigation group showed the highest wall shear stress along with the greatest magnitude of velocity.

  13. Dynamic CT in patients with normal pressure hydrocephalus

    Energy Technology Data Exchange (ETDEWEB)

    Horibe, Kunio; Akagi, Katsuhito; Go, Junto; Kohmura, Eiji; Yamazaki, Mami

    1984-11-01

    In order to elucidate the cerebral circulation before and after shunt in patients with normal pressure hydrocephalus(NPH), a comparative study of 12 cases was performed using dynamic CT. In the effective shunt group, blood flow in the frontal gray matter and PVL was improved. The improvement in PVL was particularly marked. On the other hand, in the non-effective group, blood flow in the frontal gray matter was reduced compared with that before operation. In regard to predicting the effectiveness of the shunt from the features of preoperative dynamic CT study in NPH, it is suggested that blood flow in the frontal gray matter was lower in the effective shunt group than in the non-effective group. This cerebral circulation study using dynamic CT, which can be easily manipulated, is non-invasive, and is thought to be a useful method when highly reproducible parameters are chosen. (Author).

  14. Molecular dynamics study of helium bubble pressure in titanium

    Science.gov (United States)

    Zhang, Bao-Ling; Wang, Jun; Hou, Qing

    2011-03-01

    In this paper, the pressure state of the helium bubble in titanium is simulated by a molecular dynamics (MD) method. First, the possible helium/vacancy ratio is determined according to therelation between the bubble pressure and helium/vacancy ratio; then the dependences of the helium bubble pressure on the bubble radius at different temperatures are studied. It is shown that the product of the bubble pressure and the radius is approximately a constant, a result justifying the pressure-radius relation predicted by thermodynamics-based theory for gas bubble. Furthermore, a state equation of the helium bubble is established based on the MD calculations. Comparison between the results obtained by the state equation and corresponding experimental data shows that the state equation can describe reasonably the state of helium bubble and thus could be used for Monte Carlo simulations of the evolution of helium bubble in metals. Project supported by the National Natural Science Foundation of China (Grant No. 10775101) and National Magnetic Confinement Fusion Program of China (Grant No. 2009GB106004).

  15. Noninvasive microbubble-based pressure measurements: a simulation study

    NARCIS (Netherlands)

    Postema, Michiel; Bouakaz, Ayache; Jong, de Nico

    2004-01-01

    This paper describes a noninvasive method to measure local hydrostatic pressures in fluid filled cavities. The method is based on the disappearance time of a gas bubble, as the disappearance time is related to the hydrostatic pressure. When a bubble shrinks, its response to ultrasound changes. From

  16. Perilymphatic pressure measurement in patients with Meniere's disease

    NARCIS (Netherlands)

    Mateijsen, DJM; Rosingh, HJ; Wit, HP; Albers, FWJ

    2001-01-01

    The MMS-10 Tympanic Displacement Analyser is a new device for measuring perilymphatic pressure in humans. This instrument was used in 70 patients with Meniere's disease (44 affected ears) and a group of 50 young normal hearing subjects. No significant differences in perilymphatic pressure measuremen

  17. Definition-consistent measurement of exchange market pressure

    NARCIS (Netherlands)

    Klaassen, F.; Jager, H.

    2011-01-01

    Currencies can be under severe pressure, but in a managed exchange rate regime that is not fully visible via the change in the exchange rate. The literature has proposed a way to measure such exchange market pressure (EMP) indirectly, by adding interest rate changes and forex interventions to the

  18. Definition-consistent measurement of exchange market pressure

    NARCIS (Netherlands)

    Klaassen, F.; Jager, H.

    2011-01-01

    Currencies can be under severe pressure, but in a managed exchange rate regime that is not fully visible via the change in the exchange rate. The literature has proposed a way to measure such exchange market pressure (EMP) indirectly, by adding interest rate changes and forex interventions to the ex

  19. Perilymphatic pressure measurement in patients with Meniere's disease

    NARCIS (Netherlands)

    Mateijsen, DJM; Rosingh, HJ; Wit, HP; Albers, FWJ

    The MMS-10 Tympanic Displacement Analyser is a new device for measuring perilymphatic pressure in humans. This instrument was used in 70 patients with Meniere's disease (44 affected ears) and a group of 50 young normal hearing subjects. No significant differences in perilymphatic pressure

  20. Dynamic contact angle measurements on superhydrophobic surfaces

    Science.gov (United States)

    Kim, Jeong-Hyun; Kavehpour, H. Pirouz; Rothstein, Jonathan P.

    2015-03-01

    In this paper, the dynamic advancing and receding contact angles of a series of aqueous solutions were measured on a number of hydrophobic and superhydrophobic surfaces using a modified Wilhelmy plate technique. Superhydrophobic surfaces are hydrophobic surfaces with micron or nanometer sized surface roughness. These surfaces have very large static advancing contact angles and little static contact angle hysteresis. In this study, the dynamic advancing and dynamic receding contact angles on superhydrophobic surfaces were measured as a function of plate velocity and capillary number. The dynamic contact angles measured on a smooth hydrophobic Teflon surface were found to obey the scaling with capillary number predicted by the Cox-Voinov-Tanner law, θD3 ∝ Ca. The response of the dynamic contact angle on the superhydrophobic surfaces, however, did not follow the same scaling law. The advancing contact angle was found to remain constant at θA = 160∘, independent of capillary number. The dynamic receding contact angle measurements on superhydrophobic surfaces were found to decrease with increasing capillary number; however, the presence of slip on the superhydrophobic surface was found to result in a shift in the onset of dynamic contact angle variation to larger capillary numbers. In addition, a much weaker dependence of the dynamic contact angle on capillary number was observed for some of the superhydrophobic surfaces tested.

  1. Molecular dynamics of water at high temperatures and pressures

    Science.gov (United States)

    Brodholt, John; Wood, Bernard

    1990-09-01

    There are currently no precise P-V-T data for water at pressures above 8.9 kbars and temperatures above 900°C. Many petrological processes in the lower crust and upper mantle take place under more extreme conditions, however and petrologists commonly rely on empirical equations of state such as the modified Redlich-Kwong equation (MRK) to extrapolate the low pressure data. In this study we have taken an alternative approach and attempted to simulate the P-V-T properties of water using molecular dynamics. The TIP4P intermolecular potential for H 2O ( JORGENSEN et al., 1983) has had considerable success predicting the properties of water at low temperatures and pressures up to 10 kbar ( MADURA et al., 1988). We have extended its application by making molecular dynamics (MD) simulations at a density of 1.0 g/cc from 300 to 2300 K and 0.5 to 40 kbars. The results agree with the P-V-T data of BURNHAM et al. (1969) (up to 10 kbars) with an average error of under 2%. This is a much better concordance than is obtained with any of the currently used versions of MRK. At 300 kbars and 2000 K the MD simulations predict densities within 8% of those obtained in the shock wave experiments of KORMER (1968). This is a very good agreement given the fact that water ionizes to some extent at high pressures ( MITCHELL and NELLIS, 1982) and we have made no provisions for this effect. We conclude that molecular dynamics simulations provide the possibility of estimating P-V-T properties in the upper mantle P-T regime with very good accuracy.

  2. Signal transforms in dynamic measurements

    CERN Document Server

    Layer, Edward

    2015-01-01

    This book is devoted to the analysis of measurement signals which requires specific mathematical operations like Convolution, Deconvolution, Laplace, Fourier, Hilbert, Wavelet or Z transform which are all presented in the present book. The different problems refer to the modulation of signals, filtration of disturbance as well as to the orthogonal signals and their use in digital form for the measurement of current, voltage, power and frequency are also widely discussed. All the topics covered in this book are presented in detail and illustrated by means of examples in MathCad and LabVIEW. This book provides a useful source for researchers, scientists and engineers who in their daily work are required to deal with problems of measurement and signal processing and can also be helpful to undergraduate students of electrical engineering.    

  3. Automatic noninvasive measurement of systolic blood pressure using photoplethysmography

    Directory of Open Access Journals (Sweden)

    Glik Zehava

    2009-10-01

    Full Text Available Abstract Background Automatic measurement of arterial blood pressure is important, but the available commercial automatic blood pressure meters, mostly based on oscillometry, are of low accuracy. Methods In this study, we present a cuff-based technique for automatic measurement of systolic blood pressure, based on photoplethysmographic signals measured simultaneously in fingers of both hands. After inflating the pressure cuff to a level above systolic blood pressure in a relatively slow rate, it is slowly deflated. The cuff pressure for which the photoplethysmographic signal reappeared during the deflation of the pressure-cuff was taken as the systolic blood pressure. The algorithm for the detection of the photoplethysmographic signal involves: (1 determination of the time-segments in which the photoplethysmographic signal distal to the cuff is expected to appear, utilizing the photoplethysmographic signal in the free hand, and (2 discrimination between random fluctuations and photoplethysmographic pattern. The detected pulses in the time-segments were identified as photoplethysmographic pulses if they met two criteria, based on the pulse waveform and on the correlation between the signal in each segment and the signal in the two neighboring segments. Results Comparison of the photoplethysmographic-based automatic technique to sphygmomanometry, the reference standard, shows that the standard deviation of their differences was 3.7 mmHg. For subjects with systolic blood pressure above 130 mmHg the standard deviation was even lower, 2.9 mmHg. These values are much lower than the 8 mmHg value imposed by AAMI standard for automatic blood pressure meters. Conclusion The photoplethysmographic-based technique for automatic measurement of systolic blood pressure, and the algorithm which was presented in this study, seems to be accurate.

  4. Software Development for JSA Dynamic Parameter Measurement

    Institute of Scientific and Technical Information of China (English)

    LUO; Huang-da

    2013-01-01

    We have developed a series of experiment measurement system for Jordan sub-critical assembly.The dynamic parameter measurement system is used for measuring the prompt neutron decaying constant,a physics parameter of reactor character.It mainly consists of a 3He neutron detector in the reactor core,

  5. Transport measurements under pressure in III-IV layered semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Segura, A.; Errandonea, D.; Martinez-Garcia, D. [ICMUV, Universitat de Valencia, Ed. Investigacio, 46100 Burjassot (Spain); Manjon, F.J. [Dpto. de Fisica Aplicada, Univ. Politecnica de Valencia, Cno. de Vera s/n, 46022 Valencia (Spain); Chevy, A. [Physique des Milieux Condenses, Universite Pierre et Marie Curie, 75252 Paris Cedex 05 (France); Tobias, G.; Ordejon, P.; Canadell, E. [Institut de Ciencia dels Materials de Barcelona, CSIC, Campus de la UAB, 08193 Bellaterra (Barcelona) (Spain)

    2007-01-15

    This paper reports on Hall effect, resistivity and thermopower effect measurements under high pressure up to 12 GPa in p-type {gamma}-indium selenide (InSe) and {epsilon}-gallium selenide (GaSe). The paper focuses on two applications of transport measurements under pressure: electronic structure and phase transition studies. As concerns the electronic structure, we investigate the origin of the striking differences between the pressure behaviour of transport parameters in both layered compounds. While the hole concentration and mobility increase moderately and monotonously in {epsilon}-GaSe up to 10 GPa, a large increase of the hole concentration at near 0.8 GPa and a large continuous increase of the hole mobility, which doubled its ambient pressure value by 3.2 GPa, is observed in {gamma}-InSe. Based on electronic structure calculations the difference is found to arise from the pressure evolution of the valence band maximum. While the shape of the valence band maximum is virtually pressure-insensitive in {epsilon}-GaSe, it changes dramatically in {gamma}-InSe, with the emergence of a ring-shaped subsidiary maximum that becomes the absolute valence-band maximum as pressure increases. Transport measurements as a function of pressure and temperature are also used to investigate the phase diagram of InSe and, in particular, the transition to the rock-salt polymorph. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  6. Oil Pressure Signal Attenuation Resistance Monitoring System Design Based on Content Networking Dynamic Measurement%基于物联网压力动态测量中油井信号抗衰减监测系统设计

    Institute of Scientific and Technical Information of China (English)

    韦抒

    2013-01-01

      针对传统的油井开采过程中压力变化动态性较强,区域较为广阔,当面对井喷、井漏风险的井下情况时,压力波会随着距离的传递发生明显地衰减,系统检测存在局限性与不确定性的问题,本文提出一种基于物联网压力动态监控的油井意外风险检测系统,详细分析了油井生产中的各种相关数据产生与处理,以无线传感网络为基础搭建物联网硬件平台,使用信息增益比,作为软件设计中决策树属性分裂的衡量指标,对冗余属性进行了合理地约束。实验证明,这种方法能够将传统油井危险情况预测的准确率大幅度提高,对实际的油井生产提供有效指导。%  Based on the traditional oil well drilling pressure changes in the process of dynamic, strong regional relatively broad, when faced with underground blowout, the risk of well leakage, pressure wave will happen with the distance relay obvious attenuation, system testing limitations and uncertainty. Therefore proposed based on content networking pressure dynamic monitoring of the oil wells risks incident detection system, a detailed analysis of the oil well production all sorts of relevant data and processing, based on wireless sensor network structures networking hardware platform, the use of in-formation gain than for decision tree attributes in the software design of indexes, the redundant attributes of the reason-able restraint. Experiments show that this method can be traditional oil wells of dangerous situation prediction accuracy greatly raised, provide effective guidance for actual production of oil wells.

  7. Method and Apparatus for Measuring Surface Air Pressure

    Science.gov (United States)

    Lin, Bing (Inventor); Hu, Yongxiang (Inventor)

    2014-01-01

    The present invention is directed to an apparatus and method for remotely measuring surface air pressure. In one embodiment, the method of the present invention utilizes the steps of transmitting a signal having multiple frequencies into the atmosphere, measuring the transmitted/reflected signal to determine the relative received power level of each frequency and then determining the surface air pressure based upon the attenuation of the transmitted frequencies.

  8. Quantitative analysis of sensor for pressure waveform measurement

    Directory of Open Access Journals (Sweden)

    Tyan Chu-Chang

    2010-01-01

    Full Text Available Abstract Background Arterial pressure waveforms contain important diagnostic and physiological information since their contour depends on a healthy cardiovascular system 1. A sensor was placed at the measured artery and some contact pressure was used to measure the pressure waveform. However, where is the location of the sensor just about enough to detect a complete pressure waveform for the diagnosis? How much contact pressure is needed over the pulse point? These two problems still remain unresolved. Method In this study, we propose a quantitative analysis to evaluate the pressure waveform for locating the position and applying the appropriate force between the sensor and the radial artery. The two-axis mechanism and the modified sensor have been designed to estimate the radial arterial width and detect the contact pressure. The template matching method was used to analyze the pressure waveform. In the X-axis scan, we found that the arterial diameter changed waveform (ADCW and the pressure waveform would change from small to large and then back to small again when the sensor was moved across the radial artery. In the Z-axis scan, we also found that the ADCW and the pressure waveform would change from small to large and then back to small again when the applied contact pressure continuously increased. Results In the X-axis scan, the template correlation coefficients of the left and right boundaries of the radial arterial width were 0.987 ± 0.016 and 0.978 ± 0.028, respectively. In the Z-axis scan, when the excessive contact pressure was more than 100 mm Hg, the template correlation was below 0.983. In applying force, when using the maximum amplitude as the criteria level, the lower contact pressure (r = 0.988 ± 0.004 was better than the higher contact pressure (r = 0.976 ± 0.012. Conclusions Although, the optimal detective position has to be close to the middle of the radial arterial, the pressure waveform also has a good completeness with

  9. Compression-tracking photoacoustic perfusion and microvascular pressure measurements

    Science.gov (United States)

    Choi, Min; Zemp, Roger

    2017-03-01

    We propose a method to measure blood pressure of small vessels non-invasively and in-vivo: by combining PA imaging with compression US. Using this method, we have shown pressure-lumen area tracking, as well as estimation of the internal vessel pressure, located 2 mm deep in tissue. Additionally, reperfusion can be tracked by measuring the total PA signal within a region of interest (ROI) after compression has been released. The ROI is updated using cross-correlation based displacement tracking1. The change in subcutaneous perfusion rates can be seen when the temperature of the hand of a human subject drops below the normal.

  10. A note on measurement of sound pressure with intensity probes

    DEFF Research Database (Denmark)

    Juhl, Peter; Jacobsen, Finn

    2004-01-01

    be improved under a variety of realistic sound field conditions by applying a different weighting of the two pressure signals from the probe. The improved intensity probe can measure the sound pressure more accurately at high frequencies than an ordinary sound intensity probe or an ordinary sound level meter......The effect of scattering and diffraction on measurement of sound pressure with "two-microphone" sound intensity probes is examined using an axisymmetric boundary element model of the probe. Whereas it has been shown a few years ago that the sound intensity estimated with a two-microphone probe...

  11. On the Dynamics of Bohmian Measures

    KAUST Repository

    Markowich, Peter A.

    2012-05-08

    The present work is devoted to the study of dynamical features of Bohmian measures, recently introduced by the authors. We rigorously prove that for sufficiently smooth wave functions the corresponding Bohmian measure furnishes a distributional solution of a nonlinear Vlasov-type equation. Moreover, we study the associated defect measures appearing in the classical limit. In one space dimension, this yields a new connection between mono-kinetic Wigner and Bohmian measures. In addition, we shall study the dynamics of Bohmian measures associated to so-called semi-classical wave packets. For these type of wave functions, we prove local in-measure convergence of a rescaled sequence of Bohmian trajectories towards the classical Hamiltonian flow on phase space. Finally, we construct an example of wave functions whose limiting Bohmian measure is not mono-kinetic but nevertheless equals the associated Wigner measure. © 2012 Springer-Verlag.

  12. Use of Tekscan K-Scan Sensors for Retropatellar Pressure Measurement Avoiding Errors during Implantation and the Effects of Shear Forces on the Measurement Precision

    OpenAIRE

    Wilharm, A; Ch. Hurschler; Dermitas, T; Bohnsack, M.

    2013-01-01

    Pressure-sensitive K-Scan 4000 sensors (Tekscan, USA) provide new possibilities for the dynamic measurement of force and pressure in biomechanical investigations. We examined the sensors to determine in particular whether they are also suitable for reliable measurements of retropatellar forces and pressures. Insertion approaches were also investigated and a lateral parapatellar arthrotomy supplemented by parapatellar sutures proved to be the most reliable method. The ten human cadaver knees w...

  13. High dynamic range charge measurements

    Energy Technology Data Exchange (ETDEWEB)

    De Geronimo, Gianluigi

    2012-09-04

    A charge amplifier for use in radiation sensing includes an amplifier, at least one switch, and at least one capacitor. The switch selectively couples the input of the switch to one of at least two voltages. The capacitor is electrically coupled in series between the input of the amplifier and the input of the switch. The capacitor is electrically coupled to the input of the amplifier without a switch coupled therebetween. A method of measuring charge in radiation sensing includes selectively diverting charge from an input of an amplifier to an input of at least one capacitor by selectively coupling an output of the at least one capacitor to one of at least two voltages. The input of the at least one capacitor is operatively coupled to the input of the amplifier without a switch coupled therebetween. The method also includes calculating a total charge based on a sum of the amplified charge and the diverted charge.

  14. Measuring the local pressure amplitude in microchannel acoustophoresis

    DEFF Research Database (Denmark)

    Barnkob, Rune; Augustsson, Per; Laurell, Thomas

    2010-01-01

    A new method is reported on how to measure the local pressure amplitude and the Q factor of ultrasound resonances in microfluidic chips designed for acoustophoresis of particle suspensions. The method relies on tracking individual polystyrene tracer microbeads in straight water-filled silicon...... of the microbeads. From the curve fits we obtain the acoustic energy density, and hence the pressure amplitude as well as the acoustophoretic force. By plotting the obtained energy densities as a function of applied frequency, we obtain Lorentzian line shapes, from which the resonance frequency and the Q factor...... for each resonance peak are derived. Typical measurements yield acoustic energy densities of the order of 10 J/m3, pressure amplitudes of 0.2 MPa, and Q factors around 500. The observed half wavelength of the transverse acoustic pressure wave is equal within 2% to the measured width w = 377 m...

  15. Validation of NIS 500 MPa hydraulic pressure measurement

    Directory of Open Access Journals (Sweden)

    Eltawil Alaaeldin A.

    2017-01-01

    Full Text Available 500 MPa pressure is considered as the common maximum pressure in most of the National Metrology Institutes worldwide; however, validation of the uncertainty in that range required a lot of work. NIS when recognized on, 2008 guaranteed big uncertainty value above 200 MPa due to the absence of international comparison at that time. This paper summarizes the results of a validation of 500 MPa range of hydraulic gauge pressure measurements carried out at NIS. The study covers the calibration through direct comparison and through using of a pressure sensor. The paper summarized the technical work carried out at the results of measurements and the effect of these results on NIS Calibration Measurements Capability. The validation also includes the comparison between the obtained results and pervious calibration of the same piston-cylinder assembly that calibrated against the NIST primary standard.

  16. MEASUREMENT OF FRICTIONAL PRESSURE DIFFERENTIALS DURING A VENTILATION SURVEY

    Energy Technology Data Exchange (ETDEWEB)

    B.S. Prosser, PE; I.M. Loomis, PE, PhD

    2003-11-03

    During the course of a ventilation survey, both airflow quantity and frictional pressure losses are measured and quantified. The measurement of airflow has been extensively studied as the vast majority of ventilation standards/regulations are tied to airflow quantity or velocity. However, during the conduct of a ventilation survey, measurement of airflow only represents half of the necessary parameters required to directly calculate the airway resistance. The measurement of frictional pressure loss is an often misunderstood and misapplied part of the ventilation survey. This paper compares the two basic methods of frictional pressure drop measurements; the barometer and the gauge and tube. Personal experiences with each method will be detailed along with the authors' opinions regarding the applicability and conditions favoring each method.

  17. Can a Pressure Standard be Based on Capacitance Measurements?

    Science.gov (United States)

    Moldover, Michael R

    1998-01-01

    We consider the feasibility of basing a pressure standard on measurements of the dielectric constant ϵ and the thermodynamic temperature T of helium near 0 °C. The pressure p of the helium would be calculated from fundamental constants, quantum mechanics, and statistical mechanics. At present, the relative standard uncertainty of the pressure ur(p) would exceed 20 × 10(-6), the relative uncertainty of the value of the molar polarizability of helium Aϵ calculated ab initio. If the relativistic corrections to Aϵ were calculated as accurately as the classical value is now known, a capacitance-based pressure standard might attain ur(p) < 6 × 10(-6) for pressures near 1 MPa, a result of considerable interest for pressure metrology. One obtains p by eliminating the density from the virial expansions for p and ϵ - 1. If ϵ - 1 were measured with a very stable, 0.5 pF toroidal cross capacitor, the small capacitance and the small values of ϵ - 1 would require state-of-the-art capacitance measurements to achieve a useful pressure standard.

  18. Dynamic response of nuclear fuel assembly excited by pressure pulsations

    Directory of Open Access Journals (Sweden)

    Zeman V.

    2012-12-01

    Full Text Available The paper deals with dynamic load calculation of the hexagonal type nuclear fuel assembly caused by spatial motion of the support plates in the reactor core. The support plate motion is excited by pressure pulsations generated by main circulation pumps in the coolant loops of the primary circuit of the nuclear power plant. Slightly different pumps revolutions generate the beat vibrations which causes an amplification of fuel assembly component dynamic deformations and fuel rods coating abrasion. The cyclic and central symmetry of the fuel assembly makes it possible the system decomposition into six identical revolved fuel rod segments which are linked with central tube and skeleton by several spacer grids in horizontal planes.The modal synthesis method with condensation of the fuel rod segments is used for calculation of the normal and friction forces transmitted between fuel rods and spacer grids cells.

  19. Correction of static pressure on a research aircraft in accelerated flight using differential pressure measurements

    Directory of Open Access Journals (Sweden)

    A. R. Rodi

    2012-05-01

    Full Text Available Geometric altitude data from a combined Global Navigation Satellite System (GNSS and inertial measurement unit (IMU system on the University of Wyoming King Air research aircraft are used to estimate acceleration effects on static pressure measurement. Using data collected during periods of accelerated flight, comparison of measured pressure with that derived from GNSS/IMU geometric altitude show that errors exceeding 150 Pa can occur which is significant in airspeed and atmospheric air motion determination. A method is developed to predict static pressure errors from analysis of differential pressure measurements from a Rosemount model 858 differential pressure air velocity probe. The method was evaluated with a carefully designed probe towed on connecting tubing behind the aircraft – a "trailing cone" – in steady flight, and shown to have a precision of about ±10 Pa over a wide range of conditions including various altitudes, power settings, and gear and flap extensions. Under accelerated flight conditions, compared to the GNSS/IMU data, this algorithm predicts corrections to a precision of better than ±20 Pa. Some limiting factors affecting the precision of static pressure measurement on a research aircraft are examined.

  20. Improved method of measuring pressure coupled response for composite solid propellants

    Science.gov (United States)

    Su, Wanxing; Wang, Ningfei; Li, Junwei; Zhao, Yandong; Yan, Mi

    2014-04-01

    Pressure coupled response is one of the main causes of combustion instability in the solid rocket motor. It is also a characteristic parameter for predicting the stability. The pressure coupled response function is usually measured by different methods to evaluate the performance of new propellant. Based on T-burner and "burning surface doubled and secondary attenuation", an improved method for measuring the pressure coupled response of composite propellant is introduced in this article. A computational fluid dynamics (CFD) study has also been conducted to validate the method and to understand the pressure oscillation phenomenon in T-burner. Three rounds of tests were carried out on the same batch of aluminized AP/HTPB composite solid propellant. The experimental results show that the sample propellant had a high response function under the conditions of high pressure (~11.5 MPa) and low frequency (~140 Hz). The numerically predicted oscillation frequency and amplitude are consistent with the experimental results. One practical solid rocket motor using this sample propellant was found to experience pressure oscillation at the end of burning. This confirms that the sample propellant is prone to combustion instability. Finally, acoustic pressure distribution and phase difference in T-burner were analyzed. Both the experimental and numerical results are found to be associated with similar acoustic pressure distribution. And the phase difference analysis showed that the pressure oscillations at the head end of the T-burner are 180° out of phase from those in the aft end of the T-burner.

  1. Dynamic Diamond Anvil Cell (dDAC): A novel device for studying the dynamic-pressure properties of materials

    Energy Technology Data Exchange (ETDEWEB)

    Evans, W J; Yoo, C; Lee, G W; Cynn, H; Lipp, M J; Visbeck, K

    2007-02-23

    We have developed a unique device, a dynamic diamond anvil cell (dDAC), which repetitively applies a time-dependent load/pressure profile to a sample. This capability allows studies of the kinetics of phase transitions and metastable phases at compression (strain) rates of up to 500 GPa/sec ({approx}0.16 s{sup -1} for a metal). Our approach adapts electromechanical piezoelectric actuators to a conventional diamond anvil cell design, which enables precise specification and control of a time-dependent applied load/pressure. Existing DAC instrumentation and experimental techniques are easily adapted to the dDAC to measure the properties of a sample under the varying load/pressure conditions. This capability addresses the sparsely studied regime of dynamic phenomena between static research (diamond anvil cells and large volume presses) and dynamic shock-driven experiments (gas guns, explosive and laser shock). We present an overview of a variety of experimental measurements that can be made with this device.

  2. A method of measuring dynamic strain under electromagnetic forming conditions.

    Science.gov (United States)

    Chen, Jinling; Xi, Xuekui; Wang, Sijun; Lu, Jun; Guo, Chenglong; Wang, Wenquan; Liu, Enke; Wang, Wenhong; Liu, Lin; Wu, Guangheng

    2016-04-01

    Dynamic strain measurement is rather important for the characterization of mechanical behaviors in electromagnetic forming process, but it has been hindered by high strain rate and serious electromagnetic interference for years. In this work, a simple and effective strain measuring technique for physical and mechanical behavior studies in the electromagnetic forming process has been developed. High resolution (∼5 ppm) of strain curves of a budging aluminum tube in pulsed electromagnetic field has been successfully measured using this technique. The measured strain rate is about 10(5) s(-1), which depends on the discharging conditions, nearly one order of magnitude of higher than that under conventional split Hopkins pressure bar loading conditions (∼10(4) s(-1)). It has been found that the dynamic fracture toughness of an aluminum alloy is significantly enhanced during the electromagnetic forming, which explains why the formability is much larger under electromagnetic forging conditions in comparison with conventional forging processes.

  3. Pressure-produced ionization of nonideal plasma in a megabar range of dynamic pressures

    NARCIS (Netherlands)

    Fortov, VE; Ternovoi, VY; Zhernokletov, MV; Mochalov, MA; Mikhailov, AL; Filimonov, AS; Pyalling, AA; Mintsev, VB; Gryaznov, VK; Iosilevskii, IL

    2003-01-01

    The low-frequency electrical conductivity of strongly nonideal hydrogen, helium, and xenon plasmas was measured in the megabar range of pressures. The plasmas in question were generated by the method of multiple shock compression in planar and cylindrical geometries, whereby it was possible to reduc

  4. Relaxation dynamics of lysozyme in solution under pressure: Combining molecular dynamics simulations and quasielastic neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Calandrini, V. [Centre de Biophysique Moleculaire, Rue Charles Sadron, 45071 Orleans (France); Synchrotron Soleil, L' Orme de Merisiers, B.P. 48, 91192 Gif-sur-Yvette (France); Hamon, V. [Centre de Biophysique Moleculaire, Rue Charles Sadron, 45071 Orleans (France); Hinsen, K. [Centre de Biophysique Moleculaire, Rue Charles Sadron, 45071 Orleans (France); Synchrotron Soleil, L' Orme de Merisiers, B.P. 48, 91192 Gif-sur-Yvette (France); Calligari, P. [Centre de Biophysique Moleculaire, Rue Charles Sadron, 45071 Orleans (France); Institut Laue-Langevin, 6 Rue Jules Horowitz, B.P. 156, 38042 Grenoble (France); Laboratoire Leon Brillouin, CEA Saclay, 91191 Gif-sur-Yvette (France); Bellissent-Funel, M.-C. [Laboratoire Leon Brillouin, CEA Saclay, 91191 Gif-sur-Yvette (France); Kneller, G.R. [Centre de Biophysique Moleculaire, Rue Charles Sadron, 45071 Orleans (France); Synchrotron Soleil, L' Orme de Merisiers, B.P. 48, 91192 Gif-sur-Yvette (France)], E-mail: kneller@cnrs-orleans.fr

    2008-04-18

    This paper presents a study of the influence of non-denaturing hydrostatic pressure on the relaxation dynamics of lysozyme in solution, which combines molecular dynamics simulations and quasielastic neutron scattering experiments. We compare results obtained at ambient pressure and at 3 kbar. Experiments have been performed at pD 4.6 and at a protein concentration of 60 mg/ml. For both pressures we checked the monodispersity of the protein solution by small angle neutron scattering. To interpret the simulation results and the experimental data, we adopt the fractional Ornstein-Uhlenbeck process as a model for the internal relaxation dynamics of the protein. On the experimental side, global protein motions are accounted for by the model of free translational diffusion, neglecting the much slower rotational diffusion. We find that the protein dynamics in the observed time window from about 1 to 100 ps is slowed down under pressure, while its fractal characteristics is preserved, and that the amplitudes of the motions are reduced by about 20%. The slowing down of the relaxation is reduced with increasing q-values, where more localized motions are seen.

  5. Dynamic Acousto-Elasticity: Pressure and Frequency Dependences in Berea Sandstone.

    Science.gov (United States)

    Riviere, J. V.; Pimienta, L.; Latour, S.; Fortin, J.; Schubnel, A.; Johnson, P. A.

    2014-12-01

    Nonlinear elasticity is studied at the laboratory scale with the goal of understanding observations at earth scales, for instance during strong ground motion, tidal forcing and earthquake slip processes. Here we report frequency and pressure dependences on elasticity when applying dynamic acousto-elasticity (DAE) of rock samples, analogous to quasi-static acousto-elasticity. DAE allows one to obtain the elastic behavior over the entire dynamic cycle, detailing the full nonlinear behavior under tension and compression, including hysteresis and memory effects. We perform DAE on a sample of Berea sandstone subject to 0.5MPa uniaxial load, with sinusoidal oscillating strain amplitudes ranging from 10-6 to 10-5 and at frequencies from 0.1 to 260Hz. In addition, the confining pressure is increased stepwise from 0 to 30MPa. We compare results to previous measurements made at lower (mHz) and higher (kHz) frequencies. Nonlinear elastic parameters corresponding to conditioning effects, third order elastic constants and fourth order elastic constants are quantitatively compared over the pressure and frequency ranges. We observe that the decrease in modulus due to conditioning increases with frequency, suggesting a frequency and/or strain-rate dependence that should be included in nonlinear elastic models of rocks. In agreement with previous measurements, nonlinear elastic effects also decrease with confining pressure, suggesting that nonlinear elastic sources such as micro-cracks, soft bonds and dislocations are turned off as the pressure increases.

  6. [Measuring pressure distribution on the human tibia in ski boots].

    Science.gov (United States)

    Schaff, P; Hauser, W

    1987-09-01

    Pressure distribution inside shoes is of great importance for orthopaedic and biomechanical inquiries. Especially in sports, safety and comfort depend essentially on this quantity, which also determines whether a shoe is well suited for a certain discipline. Therefore, the measurement of pressure distribution allows detailed and objective statements about these factors. Using a set of newly developed thin and highly flexible measuring mats and the corresponding electronic equipment, such statements have become possible. First results with this method were obtained in alpine skiing. 8 different types of ski boots (sizes 5 and 8) worn by 14 subjects were tested on different foreward leans and temperatures using 7-point measuring mats (2 cm2/point) fixed between the boot shaft and the front of the lower leg of each leg. Additional measurements on three different types of boots using a 3 x 24-point mat (1 cm2/point) for the lower leg, as well as measurements underneath the foot with a 14-point (2 cm2/point) and a 80-point (1 cm2/point) mat were performed. A complementary determination of the force at the heel element of a ski binding and a registration of muscular activity (EMG) helped in the interpretation of the results. Some field research using telemetry completed our study. Considerable variations between different boots were found in value and location of pressure maxima. Traditional boots show high pressure values over the instep at foreward leans of 35 degrees and a rise of pressure underneath the forefoot while fixing the buckles, whereas minimal pressure over the instep, no compression of the forefoot and a pressure maximum near the upper end of the shaft are observed in rear entry boots. The force at the heel-important for binding release-varies widely between different boots at the same foreward lean. There was no asymmetry between the pressure distributions of right and left. The pressure distributions for different subjects measured in the same boot were

  7. Foldable micro coils for a transponder system measuring intraocular pressure

    Energy Technology Data Exchange (ETDEWEB)

    Ullerich, S.; Schnakenberg, U. [Technische Hochschule Aachen (Germany). Inst. of Materials in Electrical Engineering 1; Mokwa, W. [Technische Hochschule Aachen (Germany). Inst. of Materials in Electrical Engineering 1]|[Fraunhofer Inst. of Microelectronic Circuits and Systems, Duisburg (Germany); Boegel, G. vom [Fraunhofer Inst. of Microelectronic Circuits and Systems, Duisburg (Germany)

    2001-07-01

    A foldable transponder system consisting of a chip and a micro coil for measuring intraocular pressure continuously is presented. The system will be integrated in the haptic of a soft artificial intraocular lens. Calculations of planar micro coils with 6 mm and 10.3 mm in diameter show the limits for planar coils with an outer diameter of 6 mm. For the realisation of the transponder system a 20 {mu}m thick coil with an outer diameter of 10.3 mm, an inner diameter of 7.7 mm, 16 turns and a gap of 20 {mu}m between the windings was selected. Measurements show a good agreement between calculated and measured values. Wireless pressure measurements were carried out showing a linear behaviour of the output signal with respect to the applied pressure. (orig.)

  8. Cardiac MR Elastography: Comparison with left ventricular pressure measurement

    Directory of Open Access Journals (Sweden)

    Samani Abbas

    2009-11-01

    Full Text Available Abstract Purpose of study To compare magnetic resonance elastography (MRE with ventricular pressure changes in an animal model. Methods Three pigs of different cardiac physiology (weight, 25 to 53 kg; heart rate, 61 to 93 bpm; left ventricular [LV] end-diastolic volume, 35 to 70 ml were subjected to invasive LV pressure measurement by catheter and noninvasive cardiac MRE. Cardiac MRE was performed in a short-axis view of the heart and applying a 48.3-Hz shear-wave stimulus. Relative changes in LV-shear wave amplitudes during the cardiac cycle were analyzed. Correlation coefficients between wave amplitudes and LV pressure as well as between wave amplitudes and LV diameter were determined. Results A relationship between MRE and LV pressure was observed in all three animals (R2 ≥ 0.76. No correlation was observed between MRE and LV diameter (R2 ≤ 0.15. Instead, shear wave amplitudes decreased 102 ± 58 ms earlier than LV diameters at systole and amplitudes increased 175 ± 40 ms before LV dilatation at diastole. Amplitude ratios between diastole and systole ranged from 2.0 to 2.8, corresponding to LV pressure differences of 60 to 73 mmHg. Conclusion Externally induced shear waves provide information reflecting intraventricular pressure changes which, if substantiated in further experiments, has potential to make cardiac MRE a unique noninvasive imaging modality for measuring pressure-volume function of the heart.

  9. Blood-Pressure Measuring System Gives Accurate Graphic Output

    Science.gov (United States)

    1965-01-01

    The problem: To develop an instrument that will provide an external (indirect) measurement of arterial blood pressure in the form of an easily interpreted graphic trace that can be correlated with standard clinical blood-pressure measurements. From sphygmograms produced by conventional sphygmographs, it is very difficult to differentiate the systolic and diastolic blood-pressure pulses and to correlate these indices with the standard clinical values. It is nearly impossible to determine these indices when the subject is under physical or emotional stress. The solution: An electronic blood-pressure system, basically similar to conventional ausculatory sphygmomanometers, employing a standard occluding cuff, a gas-pressure source, and a gas-pressure regulator and valve. An electrical output transducer senses cuff pressure, and a microphone positioned on the brachial artery under the occluding cuff monitors the Korotkoff sounds from this artery. The output signals present the conventional systolic and diastolic indices in a clear, graphical display. The complete system also includes an electronic timer and cycle-control circuit.

  10. Bubble cloud dynamics in a high-pressure spherical resonator

    Science.gov (United States)

    Anderson, Phillip Andrew

    A bubble cloud is a population of bubbles confined to a region within a fluid. Bubble clouds play a large role in a variety of naturally occurring phenomena and man-made applications (e.g., ocean noise, cavitation damage, sonoluminescence, ultrasonic cleaning, drug delivery, lithotripsy). It is important, therefore, to understand the behavior of bubble clouds so that their effects may be enhanced or diminished as desired. This work explores and characterizes the properties of bubble clouds nucleated inside a high-pressure spherical acoustic resonator, in connection with recent interest in acoustic inertial confinement fusion (acoustic ICF). A laser system was developed to repeatably nucleate a cloud of bubbles inside the resonator. The resulting events were then observed, primarily with schlieren imaging methods. Preliminary studies of the bubble cloud dynamics showed the sensitivity of the initial cloud to nucleation parameters including the phase of nucleation, the laser energy, and the acoustic power. After many acoustic cycles, some bubble clouds are observed to evolve into a tight cluster. The formation of these clusters correlates with initial bubble distributions which have a large cloud interaction parameter, β. Cluster dynamics are seen to be largely driven by reconverging shock waves from previous collapses reflected from the resonator's interior surface. Initial expansion of the cluster boundary is on the order of 8 mm/µs and the maximum radius approaches 3 mm. Shock pressures are estimated to be > 10 GPa at a radius of 100 µm using weak shock theory.

  11. Measuring air pressure with a polymeric gas sensor

    Directory of Open Access Journals (Sweden)

    Juliana R. Cordeiro

    2010-01-01

    Full Text Available In this communication we describe the application of a conductive polymer gas sensor as an air pressure sensor. The device consists of a thin doped poly(4'-hexyloxy-2,5-biphenylene ethylene (PHBPE film deposited on an interdigitated metallic electrode. The sensor is cheap, easy to fabricate, lasts for several months, and is suitable for measuring air pressures in the range between 100 and 700 mmHg.

  12. Riemann problem for the zero-pressure flow in gas dynamics

    Institute of Scientific and Technical Information of China (English)

    李杰权; 荔炜

    2001-01-01

    The Riemann problem for zero-pressure flow in gas dynamics in one dimension and two dimensions is investigated. Through studying the generalized Rankine-Hugoniot conditions of delta-shock waves, the one-dimensional Riemann solution is proposed which exhibits four different structures when the initial density involves Dirac measure. For the two-dimensional case, the Riemann solution with two pieces of initial constant states separated at a smooth curve is obtained.

  13. Quantum molecular dynamics simulations of beryllium at high pressures

    Science.gov (United States)

    Desjarlais, Michael; Knudson, Marcus

    2008-03-01

    The phase boundaries and high pressure melt properties of beryllium have been the subject of several recent experimental and theoretical studies. The interest is motivated in part by the use of beryllium as an ablator material in inertial confinement fusion capsule designs. In this work, the high pressure melt curve, Hugoniot crossings, sound speeds, and phase boundaries of beryllium are explored with DFT based quantum molecular dynamics calculations. The entropy differences between the various phases of beryllium are extracted in the vicinity of the melt curve and agree favorably with earlier theoretical work on normal melting. High velocity flyer plate experiments with beryllium targets on Sandia's Z machine have generated high quality data for the Hugoniot, bulk sound speeds, and longitudinal sound speeds. This data provides a tight constraint on the pressure for the onset of shock melting of beryllium and intriguing information on the solid phase prior to melt. The results of the QMD calculations and the experimental results will be compared, and implications for the HCP and BCC phase boundaries of beryllium will be presented.

  14. Combustion dynamics of low vapour pressure nanofuel droplets

    Science.gov (United States)

    Pandey, Khushboo; Chattopadhyay, Kamanio; Basu, Saptarshi

    2017-07-01

    Multiscale combustion dynamics, shape oscillations, secondary atomization, and precipitate formation have been elucidated for low vapour pressure nanofuel [n-dodecane seeded with alumina nanoparticles (NPs)] droplets. Dilute nanoparticle loading rates (0.1%-1%) have been considered. Contrary to our previous studies of ethanol-water blend (high vapour pressure fuel), pure dodecane droplets do not exhibit internal boiling after ignition. However, variation in surface tension due to temperature causes shape deformations for pure dodecane droplets. In the case of nanofuels, intense heat release from the enveloping flame leads to the formation of micron-size aggregates (of alumina NPS) which serve as nucleation sites promoting heterogeneous boiling. Three boiling regimes (A, B, and C) have been identified with varying bubble dynamics. We have deciphered key mechanisms responsible for the growth, transport, and rupture of the bubbles. Bubble rupture causes ejections of liquid droplets termed as secondary atomization. Ejection of small bubbles (mode 1) resembles the classical vapour bubble collapse mechanism near a flat free surface. However, large bubbles induce severe shape deformations as well as bulk oscillations. Rupture of large bubbles results in high speed liquid jet formation which undergoes Rayleigh-Plateau tip break-up. Both modes contribute towards direct fuel transfer from the droplet surface to flame envelope bypassing diffusion limitations. Combustion lifetime of nanofuel droplets consequently has two stages: stage I (where bubble dynamics are dominant) and stage II (formation of gelatinous mass due to continuous fuel depletion; NP agglomeration). In the present work, variation of flame dynamics and spatio-temporal heat release (HR) have been analysed using high speed OH* chemiluminescence imaging. Fluctuations in droplet shape and flame heat release are found to be well correlated. Droplet flame is bifurcated in two zones (I and II). Flame response is

  15. Hugoniot measurements at near Gbar pressures at the NIF

    Science.gov (United States)

    Kritcher, Andrea; Swift, Damian; Doeppner, Tilo; Collins, Gilbert; Bachmann, Benjamin; Nilsen, Joe; Chapman, Dave; Correa, Alfredo; Sterne, Phil; Benedict, Lorin; Gaffney, Jim; Kraus, Dominik; Falcone, Roger; Glenzer, Siegfried; Rothman, Steve

    2015-11-01

    Laboratory measurements of the Equation of State (EOS) of matter at high pressure are of great importance in the understanding and accurate modeling of matter at extreme conditions. For example, at hundreds of Mbars - Gbar pressures atomic shell effects may come into play, which can change the predicted compressibility at given pressure due to pressure and temperature ionization. In this work we present measurements of the strong shock hugoniot, at pressures up to 720 Mbar for CH and 630 Mbar for High Density Carbon (HDC, or diamond) at the National Ignition Facility (NIF). Spherically convergent shocks are launched into solid CH or diamond samples, using a hohlraum radiation drive. X-ray radiography is applied to measure the shock speed and infer the mass density profile, enabling determining of the shock pressure and Hugoniot equation of state. This work was performed under the auspices of the U.S. Department of Energy by University of California Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48. Supported by LDRD 08-ERI-003.

  16. Blood pressure monitor with a position sensor for wrist placement to eliminate hydrostatic pressure effect on blood pressure measurement.

    Science.gov (United States)

    Sato, Hironori; Koshimizu, Hiroshi; Yamashita, Shingo; Ogura, Toshihiko

    2013-01-01

    Accurate measurement of blood pressure at wrist requires the heart and wrist to be kept at the same level to avoid the effects of hydrostatic pressure. Although a blood pressure monitor with a position sensor that guides appropriate forearm angle without use of a chair and desk has already been proposed, a similar functioning device for measuring upper arm blood pressure with a chair and desk is needed. In this study, a calculation model was first used to explore design of such a system. The findings were then implemented into design of a new blood pressure monitor. Results of various methods were compared. The calculation model of the wrist level from arthrosis angles and interarticulars lengths was developed and considered using published anthropometric dimensions. It is compared with 33 volunteer persons' experimental results. The calculated difference of level was -4.1 to 7.9 (cm) with a fixed chair and desk. The experimental result was -3.0 to 5.5 (cm) at left wrist and -2.1 to 6.3(cm) at right wrist. The absolute difference level equals ±4.8 (mmHg) of blood pressure readings according to the calculated result. This meets the AAMI requirements for a blood pressure monitor. In the conclusion, the calculation model is able to effectively evaluate the difference between the heart and wrist level. Improving the method for maintaining wrist to heart level will improve wrist blood pressure measurement accuracy when also sitting in the chair at a desk. The leading angle of user's forearm using a position sensor is shown to work for this purpose.

  17. Moving Model Test of High-Speed Train Aerodynamic Drag Based on Stagnation Pressure Measurements.

    Science.gov (United States)

    Yang, Mingzhi; Du, Juntao; Li, Zhiwei; Huang, Sha; Zhou, Dan

    2017-01-01

    A moving model test method based on stagnation pressure measurements is proposed to measure the train aerodynamic drag coefficient. Because the front tip of a high-speed train has a high pressure area and because a stagnation point occurs in the center of this region, the pressure of the stagnation point is equal to the dynamic pressure of the sensor tube based on the obtained train velocity. The first derivation of the train velocity is taken to calculate the acceleration of the train model ejected by the moving model system without additional power. According to Newton's second law, the aerodynamic drag coefficient can be resolved through many tests at different train speeds selected within a relatively narrow range. Comparisons are conducted with wind tunnel tests and numerical simulations, and good agreement is obtained, with differences of less than 6.1%. Therefore, the moving model test method proposed in this paper is feasible and reliable.

  18. A pressure and shear sensor system for stress measurement at lower limb residuum/socket interface.

    Science.gov (United States)

    Laszczak, P; McGrath, M; Tang, J; Gao, J; Jiang, L; Bader, D L; Moser, D; Zahedi, S

    2016-07-01

    A sensor system for measurement of pressure and shear at the lower limb residuum/socket interface is described. The system comprises of a flexible sensor unit and a data acquisition unit with wireless data transmission capability. Static and dynamic performance of the sensor system was characterised using a mechanical test machine. The static calibration results suggest that the developed sensor system presents high linearity (linearity error ≤ 3.8%) and resolution (0.9 kPa for pressure and 0.2 kPa for shear). Dynamic characterisation of the sensor system shows hysteresis error of approximately 15% for pressure and 8% for shear. Subsequently, a pilot amputee walking test was conducted. Three sensors were placed at the residuum/socket interface of a knee disarticulation amputee and simultaneous measurements were obtained during pilot amputee walking test. The pressure and shear peak values as well as their temporal profiles are presented and discussed. In particular, peak pressure and shear of approximately 58 kPa and 27 kPa, respectively, were recorded. Their temporal profiles also provide dynamic coupling information at this critical residuum/socket interface. These preliminary amputee test results suggest strong potential of the developed sensor system for exploitation as an assistive technology to facilitate socket design, socket fit and effective monitoring of lower limb residuum health.

  19. High Pressure Burn Rate Measurements on an Ammonium Perchlorate Propellant

    Energy Technology Data Exchange (ETDEWEB)

    Glascoe, E A; Tan, N

    2010-04-21

    High pressure deflagration rate measurements of a unique ammonium perchlorate (AP) based propellant are required to design the base burn motor for a Raytheon weapon system. The results of these deflagration rate measurements will be key in assessing safety and performance of the system. In particular, the system may experience transient pressures on the order of 100's of MPa (10's kPSI). Previous studies on similar AP based materials demonstrate that low pressure (e.g. P < 10 MPa or 1500 PSI) burn rates can be quite different than the elevated pressure deflagration rate measurements (see References and HPP results discussed herein), hence elevated pressure measurements are necessary in order understand the deflagration behavior under relevant conditions. Previous work on explosives have shown that at 100's of MPa some explosives will transition from a laminar burn mechanism to a convective burn mechanism in a process termed deconsolidative burning. The resulting burn rates that are orders-of-magnitude faster than the laminar burn rates. Materials that transition to the deconsolidative-convective burn mechanism at elevated pressures have been shown to be considerably more violent in confined heating experiments (i.e. cook-off scenarios). The mechanisms of propellant and explosive deflagration are extremely complex and include both chemical, and mechanical processes, hence predicting the behavior and rate of a novel material or formulation is difficult if not impossible. In this work, the AP/HTPB based material, TAL-1503 (B-2049), was burned in a constant volume apparatus in argon up to 300 MPa (ca. 44 kPSI). The burn rate and pressure were measured in-situ and used to calculate a pressure dependent burn rate. In general, the material appears to burn in a laminar fashion at these elevated pressures. The experiment was reproduced multiple times and the burn rate law using the best data is B = (0.6 {+-} 0.1) x P{sup (1.05{+-}0.02)} where B is the burn

  20. Bioinspired dynamic inclination measurement using inertial sensors.

    Science.gov (United States)

    Vikas, Vishesh; Crane, Carl

    2015-04-16

    Biologically, the vestibular feedback is critical to the ability of human body to balance in different conditions. This balancing ability inspires analysis of the reference equilibrium position in dynamic environments. The research proposes and experimentally validates the concept of equilibrium for the human body modeled as an inverted pendulum, which is instrumental in explaining why we align the body along the surface normal when standing on a surface but not on an incline, and tend to lean backward or forward on non-static surfaces e.g. accelerating or decelerating bus. This equilibrium position--the dynamic equilibrium axis--is dependent only on the acceleration of surface of contact (e.g. gravity) and acts as the reference to the orientation measurements. The research also draws design inspiration from the two human ears--symmetry and plurality of inertial sensors. The vestibular dynamic inclinometer and planar vestibular dynamic inclinometer consist of multiple (two or four) symmetrically placed accelerometers and a gyroscope. The sensors measure the angular acceleration and absolute orientation, not the change in orientation, from the reference equilibrium position and are successful in separating gravity from motion for objects moving on ground. The measurement algorithm is an analytical solution that is not time-recursive, independent of body dynamics and devoid of integration errors. The experimental results for the two sensor combinations validate the theoretically (kinematics) derived analytical solution of the measurement algorithm.

  1. System for water level measurement based on pressure transducer

    Science.gov (United States)

    Paczesny, Daniel; Marzecki, Michał; Woyke, Michał; Tarapata, Grzegorz

    2016-09-01

    The paper reports system for water level measurement, which is designed to be used for measuring liquid levels in the tanks of an autonomous industrial cleaning robot. The selected method of measurement utilized by the designed system is based on pressure measurement. Such system is insensitive on vibrations, foams presence and liquid impurities. The influences of variable pressure on the measurements were eliminated by utilizing the differential method and as well as the system design. The system is capable of measuring water level in tanks up to 400 mm of height with accuracy of about 2,5%. The system was tested in a container during filling and emptying with various liquids. Performed tests exhibited the linearity of the sensor characteristic and the lack of hysteresis. Obtained sensitivity of the sensor prototype was approximately 6,2 mV/mm H2O.

  2. Dynamic Properties of Impulse Measuring Systems

    DEFF Research Database (Denmark)

    Pedersen, A.; Lausen, P.

    1971-01-01

    After some basic considerations the dynamic properties of the measuring system are subjected to a general examination based on a number of responses, characteristic of the system. It is demonstrated that an impulse circuit has an internal impedance different from zero, for which reason the intera......After some basic considerations the dynamic properties of the measuring system are subjected to a general examination based on a number of responses, characteristic of the system. It is demonstrated that an impulse circuit has an internal impedance different from zero, for which reason...

  3. Innovations in plantar pressure and foot temperature measurements in diabetes.

    Science.gov (United States)

    Bus, S A

    2016-01-01

    Plantar pressure and temperature measurements in the diabetic foot primarily contribute to identifying abnormal values that increase risk for foot ulceration, and they are becoming increasingly more integrated in clinical practice and daily life of the patient. While plantar pressure measurements have long been present, only recently evidence shows their importance in ulcer prevention, as a data-driven approach to therapeutic footwear provision. The long-term monitoring of plantar pressures with the option to provide feedback, when alarming pressure levels occur, is a promising development in this area, although more technical and clinical validation is required. Shear is considered important in ulcer aetiology but is technically difficult to measure. Innovative research is underway to assess if foot temperature can act as a useful surrogate for shear. Because the skin heats up before it breaks down, frequent monitoring of foot temperature can identify these warning signals. This approach has shown to be effective in preventing foot ulcers. Innovation in diagnostic methods for foot temperature monitoring and evidence on cost effectiveness will likely facilitate implementation. Finally, monitoring of adherence to offloading treatment using temperature-based sensors has proven to be a feasible and relevant method with a wide range of possible research and patient care applications. These innovations in plantar pressure and temperature measurements illustrate an important transfer in diabetic foot care from subjective to objective evaluation of the high-risk patient. They demonstrate clinical value and a large potential in helping to reduce the patient and economic burden of diabetic foot disease.

  4. A Computer Controlled Precision High Pressure Measuring System

    Science.gov (United States)

    Sadana, S.; Yadav, S.; Jha, N.; Gupta, V. K.; Agarwal, R.; Bandyopadhyay, A. K.; Saxena, T. K.

    2011-01-01

    A microcontroller (AT89C51) based electronics has been designed and developed for high precision calibrator based on Digiquartz pressure transducer (DQPT) for the measurement of high hydrostatic pressure up to 275 MPa. The input signal from DQPT is converted into a square wave form and multiplied through frequency multiplier circuit over 10 times to input frequency. This input frequency is multiplied by a factor of ten using phased lock loop. Octal buffer is used to store the calculated frequency, which in turn is fed to microcontroller AT89C51 interfaced with a liquid crystal display for the display of frequency as well as corresponding pressure in user friendly units. The electronics developed is interfaced with a computer using RS232 for automatic data acquisition, computation and storage. The data is acquired by programming in Visual Basic 6.0. This system is interfaced with the PC to make it a computer controlled system. The system is capable of measuring the frequency up to 4 MHz with a resolution of 0.01 Hz and the pressure up to 275 MPa with a resolution of 0.001 MPa within measurement uncertainty of 0.025%. The details on the hardware of the pressure measuring system, associated electronics, software and calibration are discussed in this paper.

  5. Noninvasive blood pressure measurement scheme based on optical fiber sensor

    Science.gov (United States)

    Liu, Xianxuan; Yuan, Xueguang; Zhang, Yangan

    2016-10-01

    Optical fiber sensing has many advantages, such as volume small, light quality, low loss, strong in anti-jamming. Since the invention of the optical fiber sensing technology in 1977, optical fiber sensing technology has been applied in the military, national defense, aerospace, industrial, medical and other fields in recent years, and made a great contribution to parameter measurement in the environment under the limited condition .With the rapid development of computer, network system, the intelligent optical fiber sensing technology, the sensor technology, the combination of computer and communication technology , the detection, diagnosis and analysis can be automatically and efficiently completed. In this work, we proposed a noninvasive blood pressure detection and analysis scheme which uses optical fiber sensor. Optical fiber sensing system mainly includes the light source, optical fiber, optical detector, optical modulator, the signal processing module and so on. wavelength optical signals were led into the optical fiber sensor and the signals reflected by the human body surface were detected. By comparing actual testing data with the data got by traditional way to measure the blood pressure we can establish models for predicting the blood pressure and achieve noninvasive blood pressure measurement by using spectrum analysis technology. Blood pressure measurement method based on optical fiber sensing system is faster and more convenient than traditional way, and it can get accurate analysis results in a shorter period of time than before, so it can efficiently reduce the time cost and manpower cost.

  6. Full Dynamic-Range Pressure Sensor Matrix Based on Optical and Electrical Dual-Mode Sensing.

    Science.gov (United States)

    Wang, Xiandi; Que, Miaoling; Chen, Mengxiao; Han, Xun; Li, Xiaoyi; Pan, Caofeng; Wang, Zhong Lin

    2017-01-06

    Pressure sensor matrix (PSM) with full dynamic range can accurately detect and spatially map pressure profile. A 100 × 100 large-scale PSM gives both electrical and optical signals by itself without applying an external power. The device represents a major step toward digital imaging and visible display of pressure distribution covers a large dynamic range.

  7. Pressure-Sensitive Paint Measurements of Transient Shock Phenomena

    Directory of Open Access Journals (Sweden)

    Konstantinos Kontis

    2013-04-01

    Full Text Available Measurements of the global pressure field created by shock wave diffraction have been captured optically using a porous pressure-sensitive paint. The pressure field created by a diffracting shock wave shows large increases and decreases in pressure and can be reasonably accurately captured using CFD. The substrate, a thin-layer chromatography (TLC plate, has been dipped in a luminophore solution. TLC plates are readily available and easy to prepare. Illumination comes from two high-intensity broadband Xenon arc light sources with short-pass filters. The sample is imaged at 100 kHz using a Vision Research Phantom V710 in conjunction with a pair of long and short pass filters, creating a band. The PSP results are compared with numerical simulations of the flow using the commercial CFD package Fluent as part of ANSYS 13 for two Mach numbers.

  8. The wettability of water treatment filter media measured by dynamic osmotic pressure%基于动态渗透压力法的水处理滤料的润湿性研究

    Institute of Scientific and Technical Information of China (English)

    董会平; 何应东

    2012-01-01

    Filtration is a typical tertiary treatment method for oil-bearing water, The kinds of filter media and its surface nature have an important influence on treatment result in the filtration unit operation. The wettability of filter media is the most important influence factor. The lipophilic and hydrophilic properties of anthracite, activated zeolite, bauxite ceramic, magnetite and zeolite were studied by using dynamic osmotic Pressure method, which is based on the principle of Washburn equation. When filter media size distribution are 20~ 30 meshes and 30 40 meshes, using dynamic osmotic pressure method to study wettability of the filter media is feasible and the experiment results is precise and credible. When the particle size distribution are between 20meshes and 30 meshes, the LHR values of anthracite, activated zeolite, bauxite ceramic, magnetite and zeolite are 2.51,1.77,1.75,1.32 and 1.26 respectively, when the particle size distribution are between 30meshes and 40 meshes, the LHR values of activated zeolite, bauxite ceramic and magnetite are 2.28,2.27 and 0.86 respectively.%过滤是一种常用的含油废水深度处理方法,在过滤单元操作中,滤料的品种对处理效果有重要影响,其中滤料的润湿性是最重要的影响因素之一。本论文以Washburn方程为原理,用动态渗透压力法研究了无烟煤、活化沸石、铝矾土陶瓷、磁铁矿及沸石5中滤料的亲油亲水润湿性,当滤料粒径范围分别在20~30目和30~40目之间时,实验结果较为准确可靠。结果表明粒径范围在20~30目时,用动态渗透压力法测得的无烟煤、活化沸石、铝矾土陶瓷、磁铁矿及沸石滤料的LHR值依次为2.21、1.77、1.75、1.32和1.26;粒径范围在30~40目时,用动态渗透压力法测得的活化沸石、铝矾土陶瓷及磁铁矿滤料的LHR值依次为2.28、2.27和0.86。

  9. Comparison of model measured runner blade pressure fluctuations with unsteady flow analysis predictions

    Science.gov (United States)

    Magnoli, M. V.

    2016-11-01

    An accurate prediction of pressure fluctuations in Francis turbines has become more and more important over the last years, due to the continuously increasing requirements of wide operating range capability. Depending on the machine operator, Francis turbines are operated at full load, part load, deep part load and speed-no-load. Each of these operating conditions is associated with different flow phenomena and pressure fluctuation levels. The better understanding of the pressure fluctuation phenomena and the more accurate prediction of their amplitude along the hydraulic surfaces can significantly contribute to improve the hydraulic and mechanical design of Francis turbines, their hydraulic stability and their reliability. With the objective to acquire a deeper knowledge about the pressure fluctuation characteristics in Francis turbines and to improve the accuracy of numerical simulation methods used for the prediction of the dynamic fluid flow through the turbine, pressure fluctuations were experimentally measured in a mid specific speed model machine. The turbine runner of a model machine with specific speed around nq,opt = 60 min-1, was instrumented with dynamic pressure transducers at the runner blades. The model machine shaft was equipped with a telemetry system able to transmit the measured pressure values to the data acquisition system. The transient pressure signal was measured at multiple locations on the blade and at several operating conditions. The stored time signal was also evaluated in terms of characteristic amplitude and dominating frequency. The dynamic fluid flow through the hydraulic turbine was numerically simulated with computational fluid dynamics (CFD) for selected operating points. Among others, operating points at full load, part load and deep part load were calculated. For the fluid flow numerical simulations more advanced turbulence models were used, such as the detached eddy simulation (DES) and scale adaptive simulation (SAS). At the

  10. Measuring Surface Pressure on Rotating Compressor Blades Using Pressure Sensitive Paint

    Directory of Open Access Journals (Sweden)

    Markus Pastuhoff

    2016-03-01

    Full Text Available Pressure sensitive paint (PSP was used to measure pressure on the blades of a radial compressor with a 51 mm inlet diameter rotating at speeds up to 50 krpm using the so called lifetime method. A diode laser with a scanning-mirror system was used to illuminate the paint and the luminescent lifetime was registered using a photo multiplier. With the described technique the surface-pressure fields were acquired for eight points in the compressor map, useful for general understanding of the flow field and for CFD validation. The PSP was of so called fast type, which makes it possible to observe pressure variations with frequencies up to several kHz. Through frequency spectrum analysis we were able to detect the pulsating flow frequency when the compressor was driven to surge.

  11. Numerical Investigation of Dynamic Effects on Unsteady Flow Measurements Using a Two-Dimensional Probe

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The dynamic effects in measurements of unsteady flow when using a probe with quasi-steady calibration curves has been investigated in this paper by numerical simulation of the compressible flow around a fixed two-dimensional 3-hole probe. The unsteady velocity and pressure distributions, as well as the hole-pressures, are calculated for high frequency flow variations. The measurement errors caused by the dynamic effects indicate that considerable measurement errors may occur for high frequency flow fluctuation, e.g., 2000Hz, especially, when the flow around the probe head approaches separation. This work shows how numerical simulation can be used to investigate and correct for the dynamic effects.

  12. A novel approach to office blood pressure measurement: 30-minute office blood pressure vs daytime ambulatory blood pressure

    NARCIS (Netherlands)

    Wel, M.C. van der; Buunk, I.E.; Weel, C. van; Thien, Th.; Bakx, J.C.

    2011-01-01

    PURPOSE: Current office blood pressure measurement (OBPM) is often not executed according to guidelines and cannot prevent the white-coat effect. Serial, automated, oscillometric OBPM has the potential to overcome both these problems. We therefore developed a 30-minute OBPM method that we compared

  13. Whole-body mathematical model for simulating intracranial pressure dynamics

    Science.gov (United States)

    Lakin, William D. (Inventor); Penar, Paul L. (Inventor); Stevens, Scott A. (Inventor); Tranmer, Bruce I. (Inventor)

    2007-01-01

    A whole-body mathematical model (10) for simulating intracranial pressure dynamics. In one embodiment, model (10) includes 17 interacting compartments, of which nine lie entirely outside of intracranial vault (14). Compartments (F) and (T) are defined to distinguish ventricular from extraventricular CSF. The vasculature of the intracranial system within cranial vault (14) is also subdivided into five compartments (A, C, P, V, and S, respectively) representing the intracranial arteries, capillaries, choroid plexus, veins, and venous sinus. The body's extracranial systemic vasculature is divided into six compartments (I, J, O, Z, D, and X, respectively) representing the arteries, capillaries, and veins of the central body and the lower body. Compartments (G) and (B) include tissue and the associated interstitial fluid in the intracranial and lower regions. Compartment (Y) is a composite involving the tissues, organs, and pulmonary circulation of the central body and compartment (M) represents the external environment.

  14. Manifestation of constrained dynamics in a low pressure spark

    CERN Document Server

    Auluck, S K H

    2013-01-01

    Some features of neutron emission from dense plasma focus suggest that the participating deuterons have energy in the range of 105 eV and have a directionality of toroidal motion. Theoretical models of these devices assume that the plasma evolves through a purely irrotational flow and thus fail to predict such solenoidal flow on the scale of the plasma dimensions. Predictions of a relaxation theory are consistent with experimental data [S K H Auluck, Physics of Plasmas,18, 032508 (2011)], but the assumptions upon which it is based are not compatible with known features of these devices. There is thus no satisfactory theoretical construct which provides the necessity for solenoidal flow in these devices. This paper proposes such theoretical construct, namely, the principle of constrained dynamics, and describes an experiment which provides support for this idea. The experiment consisted of low inductance, self-breaking spark discharge in helium at a pressure ~100 hPa between two pointed electrodes separated by...

  15. Study of dynamic pressure roadway supporting scheme under condition of thick composite roof

    Institute of Scientific and Technical Information of China (English)

    Wei-Jun WANG; Li-Qiang LUO; Wei-Jian YU; Hai WU; Yan-Si QU

    2013-01-01

    This paper analyzed the strata behaviors of solid-coal roadway,gob-side entry driving and deformation law of surrounding rock in depth under high stress and thick composite roof based on the dynamic pressure roadway as engineering background in Fengcheng mining area,Jiangxi province.The results,both field measurement andnumerical simulation show that gob-side entry driving results the deformation of coal roadway main wall,however,entity-coal roadway driving results deformation of main roof and floor.The maintenance state of gob-side entry driving is better than entity-coal roadway,this situation is relevant to thick composite roof layered and easy collapse characteristics.At the same time,this paper put forward and proved proper dynamic pressure roadway supporting scheme under the surrounding rock condition and stress environment.

  16. Molecular dynamics study for the melting curve of MgO at high pressure

    Institute of Scientific and Technical Information of China (English)

    Liu Zi-Jiang; Cheng Xin-Lu; Zhang Hong; Cai Ling-Cang

    2004-01-01

    Shell-model molecular dynamics method is used to study the melting temperatures of MgO at elevated temperatures and high pressures using interaction potentials. Equations of state for MgO simulated by molecular dynamics are in good agreement with available experimental data. The pressure dependence of the melting curve of MgO has been calculated. The surface melting and superheating are considered in the correction of experimental data and the calculated values, respectively. The results of corrections are compared with those of previous work. The corrected melting temperature of MgO is consistent with corrected experimental measurements. The melting temperature of MgO up to 140GPa is calculated.

  17. Dynamic characteristics of bubbling fluidization through recurrence rate analysis of pressure fluctuations

    Institute of Scientific and Technical Information of China (English)

    Hossein Sedighikamal; Reza Zarghami

    2013-01-01

    Pressure fluctuations signals of a lab-scale fluidized bed (15 cm inner diameter and 2 m height) at different superficial gas velocities were measured.Recurrence plot (RP) and recurrence rate (RR),and the simplest variable of recurrence quantification analysis (RQA) were used to analyze the pressure signals.Different patterns observed in RP reflect different dynamic behavior of the system under study.It was also found that the variance of RR (σ2RR) could reveal the peak dominant frequencies (PDF) of different dynamic systems:completely periodic,completely stochastic,Lorenz system,and fluidized bed.The results were compared with power spectral density.Additionally,the diagram of σ2RR provides a new technique for prediction of transition velocity from bubbling to turbulent fluidization regime.

  18. Dynamic hyperinflation: is it worth measuring?

    Science.gov (United States)

    Calverley, Peter M A

    2006-05-01

    A reduced exercise capacity is an important determinant of health status and an independent prognostic marker in patients with chronic obstructive pulmonary disease. The inability to increase expiratory flow at the resting end-expiratory lung volume in the face of expiratory-flow limitation means that end-expiratory lung volume must increase if gas exchange is to be maintained near normal values. This phenomenon is usually referred to as dynamic hyperinflation. The change in operating lung volumes during exercise is related to the intensity of breathlessness. Treatments such as bronchodilators that increase inspiratory capacity or supplemental oxygen, which reduces ventilatory demand, decrease the degree of dynamic hyperinflation at any external workload. However, dynamic hyperinflation is not seen universally in patients with chronic obstructive pulmonary disease as some adopt different breathing patterns when they exercise, or respond to inhaled bronchodilators by changing their pattern of abdominal muscle activation, a behavior that can be counterproductive. Finally, dynamic hyperinflation can be reduced when, for example, breathing oxygen after exercise without changes in dyspnea, as other factors are more important determinants of this symptom in these circumstances. Dynamic hyperinflation can be reliably measured from the inspiratory capacity maneuver in many laboratories. Although knowledge about this variable gives great insight into the mechanisms of therapy, its routine measurement cannot currently be recommended as it does not appear to add additional clinical data beyond those available in present laboratory exercise testing protocols.

  19. Dynamic CT study of normal-pressure hydrocephalus

    Energy Technology Data Exchange (ETDEWEB)

    Tamaki, Norihiko; Kojima, Noriaki; Shirakuni, Takayuki; Matsumoto, Satoshi

    1984-08-01

    A dynamic CT study was performed in 14 patients with presumed normal-pressure hydrocephalus, of which diagnosis had been made by clinical symptomatology, CT findings, the results of the continuous monitoring of intracranial pressure, and CT cisternographic findings. It is demonstrated by serial CT scans that the cerebral arteries and arterioles were initially filled with contrast media, which were followed by the symmetrical and homogeneous staining of the cortical gray matter and basal ganglia, the diencephalia, and then the white matter. The venous system was stained in the late phase. The contrast media was finally cleared out from the intracranial space. Thus, the staining of the cerebral vessels and brain parenchym showed a uniform pattern in all cases. Functional CT images revealed that the patients with normal-pressure hydrocephalus who responded well to the shunt procedure had areas of prolonged mean circulation time scattered diffusely not only in the paraventricular structures, but also in the cortical gray matter of all the cerebral hemispheres. Following the shunt procedure, the hemodynamic conditions improved in almost all the areas mentioned above, but especially in the frontal and temporal gray matters and the paraventricular structures. In the patients who did not benefit from the shunt operation, however, there was no special abnormality of hemodynamic distribution. The analysis of the mean circulation time in the region of interest demonstrated that a significant improvement in cerebral hemodynamics was noted in the regions of the frontal and temporal gray matters, the periventricular white matter, and the caudate nucleus in patients who benefitted from the shunt operation. In patients who did not improve after the ventriculo-peritoneal shunt, however, there was no statistically significant difference between pre- and post-shunt mean circulation times. (J.P.N.).

  20. Heart rate variability and blood pressure during dynamic and static exercise at similar heart rate levels.

    Science.gov (United States)

    Weippert, Matthias; Behrens, Kristin; Rieger, Annika; Stoll, Regina; Kreuzfeld, Steffi

    2013-01-01

    Aim was to elucidate autonomic responses to dynamic and static (isometric) exercise of the lower limbs eliciting the same moderate heart rate (HR) response. 23 males performed two kinds of voluntary exercise in a supine position at similar heart rates: static exercise (SE) of the lower limbs (static leg press) and dynamic exercise (DE) of the lower limbs (cycling). Subjective effort, systolic (SBP) and diastolic blood pressure (DBP), mean arterial pressure (MAP), rate pressure product (RPP) and the time between consecutive heart beats (RR-intervals) were measured. Time-domain (SDNN, RMSSD), frequency-domain (power in the low and high frequency band (LFP, HFP)) and geometric measures (SD1, SD2) as well as non-linear measures of regularity (approximate entropy (ApEn), sample entropy (SampEn) and correlation dimension D2) were calculated. Although HR was similar during both exercise conditions (88±10 bpm), subjective effort, SBP, DBP, MAP and RPP were significantly enhanced during SE. HRV indicators representing overall variability (SDNN, SD 2) and vagal modulated variability (RMSSD, HFP, SD 1) were increased. LFP, thought to be modulated by both autonomic branches, tended to be higher during SE. ApEn and SampEn were decreased whereas D2 was enhanced during SE. It can be concluded that autonomic control processes during SE and DE were qualitatively different despite similar heart rate levels. The differences were reflected by blood pressure and HRV indices. HRV-measures indicated a stronger vagal cardiac activity during SE, while blood pressure response indicated a stronger sympathetic efferent activity to the vessels. The elevated vagal cardiac activity during SE might be a response mechanism, compensating a possible co-activation of sympathetic cardiac efferents, as HR and LF/HF was similar and LFP tended to be higher. However, this conclusion must be drawn cautiously as there is no HRV-marker reflecting "pure" sympathetic cardiac activity.

  1. Nocturnal blood pressure and intraocular pressure measurement in glaucoma patients and healthy controls.

    Science.gov (United States)

    Follmann, P; Palotás, C; Süveges, I; Petrovits, A

    Daytime and nocturnal intraocular pressure (IOP) values and systemic blood pressure (BP) values were compared in 60 non-glaucomatous controls, 54 glaucoma patients with normal visual field, and 46 glaucoma patients with visual field loss. The daytime IOP was measured with a Goldmann applanation tonometer and the nocturnal IOP with a Bio-Rad-Tono-Pen 2. The BP was measured with either a mercury manometer or with a Meditech ABPM-02 Ambulatory Blood Pressure Monitor, which took BP readings at 60 minute intervals. A tendency towards increasing IOP and decreasing BP was detected in the non-glaucomatous controls, within normal limits, and pathological changes of IOP and BP were observed with a significantly high occurrence (5% > P > 2%; Pearson's chi 2-test) in the glaucoma group with visual field loss.

  2. Model-free measurement of exchange market pressure

    NARCIS (Netherlands)

    F.J.G.M. Klaassen; H. Jager

    2006-01-01

    If there is exchange market pressure (EMP), monetary authorities can use the interest rate and official interventions to offset this depreciation tendency, or they can let the exchange rate change. We introduce a new approach to derive how these three variables should be combined to measure EMP. Thi

  3. Pitfalls in blood pressure measurement in daily practice

    NARCIS (Netherlands)

    Houweling, ST; Kleefstra, N; Lutgers, HL; Groenier, KH; Meyboom-de Jong, B; Bilo, HJG

    2006-01-01

    Background. Accurate blood pressure (BP) readings and correctly interpreting the obtained values are of great importance. However, there is considerable variation in the different BP measuring methods suggested in guidelines and used in hypertension trials. Objective. To compare the different method

  4. Combination of phlebography and sanguinous measurement of venous blood pressure

    Energy Technology Data Exchange (ETDEWEB)

    Weber, J.

    1988-07-01

    Phlebographic visualisation offers the highest spatial resolution of all imaging methods both in respect of veins of the leg and pelvis and of the abdomen. Phlebography offers optimal conditions for assessing morphological changes at the veins and in their direct neighbourhood. No quantitative information is available via phlebography if haemodynamics are disturbed; qualitative information is yielded merely to a restricted extent (by assessing flow velocity and collaterals). Direct sanguinous measurement of venous blood pressure is particularly suitable for the quantitative and qualitative assessment of disturbed haemodynamic conditions; in this respect it stands out among the function tests based on the employment of apparatures. If it is combined with phlebography, it is possible not only to optimise the diagnostic yield in the hands of one investigator, but also to reduce the invasiveness of both methods to one single puncture, since the puncture needle is at the same time also an instrument to measure the pressure. The article points out the possibilities and limitations of combining a) ascending phlebography of the leg and pelvis with peripheral venous pressure measurement (phlebodynamometry) and b) visualisation of the veins of the pelvis and vena cava inferior with central sanguinous venous pressure measurement (CP). Indicatious and technical execution are described.

  5. Measuring occupational stress: development of the pressure management indicator.

    Science.gov (United States)

    Williams, S; Cooper, C L

    1998-10-01

    The study of occupational stress is hindered by the lack of compact and comprehensive standardized measurement tools. The Pressure Management Indicator (PMI) is a 120-item self-report questionnaire developed from the Occupational Stress Indicator (OSI). The PMI is more reliable, more comprehensive, and shorter than the OSI. It provides an integrated measure of the major dimensions of occupational stress. The outcome scales measure job satisfaction, organizational satisfaction, organizational security, organizational commitment, anxiety--depression, resilience, worry, physical symptoms, and exhaustion. The stressor scales cover pressure from workload, relationships, career development, managerial responsibility, personal responsibility, home demands, and daily hassles. The moderator variables measure drive, impatience, control, decision latitude, and the coping strategies of problem focus, life work balance, and social support.

  6. The dynamic properties of shock-waves formed during laser ablation at sub-atmospheric pressures

    Science.gov (United States)

    Kapitan, D.; Coutts, D. W.

    2002-01-01

    The Sedov-Taylor-von Neumann (STN) theory has been shown to accurately describe the dynamic properties of shock-waves generated during pulsed-laser ablation of solid aluminium targets at visible wavelengths (510/578 nm) with 40 ns pulses with energies up to 3.5 mJ. A ballistic pendulum is used to measure the integrated recoil pressure in various inert atmospheres (He, Ne, Ar, Kr, Xe, N2, CO2, SF6) with pressures of 10-2 - 103 mbar. This recoil momentum is found to scale linearly with the background gas pressure P1 and with the square root of the molecular weight M1. More interestingly, the scaling with the ratio of heat capacities γ is verified to be a monotonically increasing function dependent on the form factor of the shock-wave. The validity of a modified STN theory which accounts for the piston mass is assessed.

  7. Evaluation of the sensing block method for dynamic force measurement

    Science.gov (United States)

    Zhang, Qinghui; Chen, Hao; Li, Wenzhao; Song, Li

    2017-01-01

    Sensing block method was proposed for the dynamic force measurement by Tanimura et al. in 1994. Comparing with the Split Hopkinson pressure bar (SHPB) technique, it can provide a much longer measuring time for the dynamic properties test of materials. However, the signals recorded by sensing block are always accompanied with additional oscillations. Tanimura et al. discussed the effect of force rising edge on the test results, whereas more research is still needed. In this paper, some more dominant factors have been extracted through dimensional analysis. The finite element simulation has been performed to assess these factors. Base on the analysis and simulation, some valuable results are obtained and some criterions proposed in this paper can be applied in design or selection of the sensing block.

  8. Gas Pressure Measurements on Space Shuttle Mission-39.

    Science.gov (United States)

    2007-11-02

    there have been numerous in-situ experiments designed to measure the gaseous contamination near the Shuttle [Green et al., 1985; Erlers et al., 1984...engines [ Erlers , 1984; Machuzak et al., 1993; Hunton, 19941. Engine-related pressure spikes were investigated by Narcisi et al. [19831, Wulf and von Zahn...Government Printing Office, Washington D.C., 1976. Erlers , H.K.F., S. Jacobs, L. Leger, and E. Miller (1984) Space Shuttle contamination measurements from

  9. Assessment of pressure field calculations from particle image velocimetry measurements

    Science.gov (United States)

    Charonko, John J.; King, Cameron V.; Smith, Barton L.; Vlachos, Pavlos P.

    2010-10-01

    This paper explores the challenges associated with the determination of in-field pressure from DPIV (digital particle image velocimetry)-measured planar velocity fields for time-dependent incompressible flows. Several methods that have been previously explored in the literature are compared, including direct integration of the pressure gradients and solution of different forms of the pressure Poisson equations. Their dependence on grid resolution, sampling rate, velocity measurement error levels and off-axis recording was quantified using artificial data of two ideal sample flow fields—a decaying vortex flow and pulsatile flow between two parallel plates, and real DPIV and pressure data from oscillating flow through a diffuser. The need for special attention to mitigate the velocity error propagation in the pressure estimation is also addressed using a physics-preserving approach based on proper orthogonal decomposition (POD). The results demonstrate that there is no unique or optimum method for estimating the pressure field and the resulting error will depend highly on the type of the flow. However, the virtual boundary, omni-directional pressure integration scheme first proposed by Liu and Katz (2006 Exp. Fluids 41 227-40) performed consistently well in both synthetic and experimental flows. Estimated errors can vary from less than 1% to over 100% with respect to the expected value, though in contrast to more traditional smoothing algorithms, the newly proposed POD-based filtering approach can reduce errors for a given set of conditions by an order of magnitude or more. This analysis offers valuable insight that allows optimizing the choice of methods and parameters based on the flow under consideration.

  10. A lidar system for measuring atmospheric pressure and temperature profiles

    Science.gov (United States)

    Schwemmer, Geary K.; Dombrowski, Mark; Korb, C. Laurence; Milrod, Jeffry; Walden, Harvey

    1987-01-01

    The design and operation of a differential absorption lidar system capable of remotely measuring the vertical structure of tropospheric pressure and temperature are described. The measurements are based on the absorption by atmospheric oxygen of the spectrally narrowband output of two pulsed alexandrite lasers. Detailed laser output spectral characteristics, which are critical to successful lidar measurements, are presented. Spectral linewidths of 0.026 and 0.018 per cm for the lasers were measured with over 99.99 percent of the energy contained in three longitudinal modes.

  11. Correlation Measure Equivalence in Dynamic Causal Structures

    CERN Document Server

    Gyongyosi, Laszlo

    2016-01-01

    We prove an equivalence transformation between the correlation measure functions of the causally-unbiased quantum gravity space and the causally-biased standard space. The theory of quantum gravity fuses the dynamic (nonfixed) causal structure of general relativity and the quantum uncertainty of quantum mechanics. In a quantum gravity space, the events are causally nonseparable and all time bias vanishes, which makes it no possible to use the standard causally-biased entropy and the correlation measure functions. Since a corrected causally-unbiased entropy function leads to an undefined, obscure mathematical structure, in our approach the correction is made in the data representation of the causally-unbiased space. We prove that the standard causally-biased entropy function with a data correction can be used to identify correlations in dynamic causal structures. As a corollary, all mathematical properties of the causally-biased correlation measure functions are preserved in the causally-unbiased space. The eq...

  12. Delocalization of Electrons in Strong Insulators at High Dynamic Pressures

    Directory of Open Access Journals (Sweden)

    William J. Nellis

    2011-06-01

    Full Text Available Systematics of material responses to shock flows at high dynamic pressures are discussed. Dissipation in shock flows drives structural and electronic transitions or crossovers, such as used to synthesize metallic liquid hydrogen and most probably Al2O3 metallic glass. The term “metal” here means electrical conduction in a degenerate system, which occurs by band overlap in degenerate condensed matter, rather than by thermal ionization in a non-degenerate plasma. Since H2 and probably disordered Al2O3 become poor metals with minimum metallic conductivity (MMC virtually all insulators with intermediate strengths do so as well under dynamic compression. That is, the magnitude of strength determines the split between thermal energy and disorder, which determines material response. These crossovers occur via a transition from insulators with electrons localized in chemical bonds to poor metals with electron energy bands. For example, radial extents of outermost electrons of Al and O atoms are 7 a0 and 4 a0, respectively, much greater than 1.7 a0 needed for onset of hybridization at 300 GPa. All such insulators are Mott insulators, provided the term “correlated electrons” includes chemical bonds.

  13. Evaluation of automated blood pressure measurements during exercise testing.

    Science.gov (United States)

    Hossack, K F; Gross, B W; Ritterman, J B; Kusumi, F; Bruce, R A

    1982-11-01

    Measurements of systolic (SBP) and diastolic (DBP) blood pressure were made at rest and during symptom-limited exercise with an automated blood pressure measuring device (EBPM). Comparisons were made between the EBPM readings and those made with mercury manometer. Correlations were high (SBP r = 0.92, DBP r = 0.80) when readings were made in the same arm, but were less satisfactory when the cuffs were on different arms (SBP r = 0.80, DBP r = 0.46). The correlation between two mercury manometer readings was SBP r = 0.90, and DBP r = 0.75. Comparison between EBPM and intra-arterial measurements were similar (SBP r = 0.74, DBP r = 0.79) to comparison between mercury manometer and intra-arterial measurements (SBP r = 0.81, DBP r = 0.61). The EBPM detected SBP at consistently higher levels than did physicians, which may be an advantage in the noisy environment of an exercise test. There was a definite tendency for physicians to record blood pressure to the nearest 10 mm Hg, whereas the frequency distribution curve for EBPM measurements was smoother. The EBPM operated satisfactorily at rest and during maximal exercise and gave as reliable measurements as a physician using a mercury manometer and, in the small number of available cases, detected exertional hypotension more often than the physician.

  14. Dynamic High Pressure Study of Chemistry and Physics of Molecular Materials

    Science.gov (United States)

    Jezowski, Sebastian Ryszard

    Both temperature and pressure control and influence the packing of molecules in crystalline phases. Our molecular simulations indicate that at ambient pressure, the cubic polymorph of tetracyanoethylene, TCNE, is the energetically stable form up to ˜ 160 K. The observed transition from the cubic to the monoclinic polymorph occurs however only at temperatures above ˜ 318 K due to the large transition barrier. The temperature-induced phase transition in TCNE studied with high-resolution IR spectroscopy is explained in terms of the increased vibrational entropy in the crystals of the monoclinic polymorph. Based upon the inverted design of the Merril-Bassett Diamond Anvil Cell, an improved, second generation dynamic Diamond Anvil Cell was developed. Based on the fluorescence of ruby crystals, we were able to demonstrate that the pressure variation range can be further increased at least up to 7 kbar and that the dynamic pressure compression of up to 1400 GPa/s can be achieved. A new class of mechanophoric system, bis-anthracene, BA, and its photoisomer, PI, is shown to respond reversibly to a mild, static pressure induced by a Diamond Anvil Cell as well as to shear deformation based on absorption spectroscopic measurements. The forward reaction occurs upon illumination with light while the back-reaction may be accelerated upon heating or mechanical stress, coupled to a rehybridization on four equivalent carbon atoms. It is an intriguing result as high pressure stabilizes the photodimerized species in related systems. Our molecular volume simulations ruled out significant differences in the volumes between bis-anthracene and its photoisomer. Kinetic absorption measurements at several different pressures reveal a negative volume of activation in the exothermic back-reaction at room temperature. Through a series of temperature-dependent kinetic measurements it is shown that the barrier of activation for the back-reaction is reduced by more than an order of magnitude at

  15. Adjustable Sample Holder With Pressure Contacts for Photoconductivity Measurement

    Directory of Open Access Journals (Sweden)

    Sanjeev Kumar

    2011-07-01

    Full Text Available A sample holder is designed to hold and apply pressure contacts on the electrodes of the photoconducting material to study the photoresponse transient. The sample holder is assembled on an aluminium base plate. The needle pointed probes are constrained to move under the spring action to provide the pressure contacts. One of the probes is provided with the facility of ± x directional movement to provide contacts on the samples having different spacing between the electrodes. The setup is simple in design and could find applications for the electrical measurements like dc conductivity and photoconductivity of semiconducting samples and can easily be assembled with scarp materials available in laboratories.

  16. Piston cylinder cell for high pressure ultrasonic pulse echo measurements

    Science.gov (United States)

    Kepa, M. W.; Ridley, C. J.; Kamenev, K. V.; Huxley, A. D.

    2016-08-01

    Ultrasonic techniques such as pulse echo, vibrating reed, or resonant ultrasound spectroscopy are powerful probes not only for studying elasticity but also for investigating electronic and magnetic properties. Here, we report on the design of a high pressure ultrasonic pulse echo apparatus, based on a piston cylinder cell, with a simplified electronic setup that operates with a single coaxial cable and requires sample lengths of mm only. The design allows simultaneous measurements of ultrasonic velocities and attenuation coefficients up to a pressure of 1.5 GPa. We illustrate the performance of the cell by probing the phase diagram of a single crystal of the ferromagnetic superconductor UGe2.

  17. [Piezoresistive sensors for medical applications exemplified by a probe for measure pressure in the rectum].

    Science.gov (United States)

    Blechschmidt-Trapp, R A; Hohlfeld, O; Müller, R; Werthschützky, R

    2002-03-01

    We described a pressure sensor probe suitable for assessing dynamic rectal pressure profiles. It comprises 10 piezoresistive sensors mounted in low-temperature co-fired ceramic. To protect against corrosion, the sensors are coated with a biocompatible silicone elastomer. The ceramic measures 4.5 x 5.5 x 1.4 mm. The entire probe has a diameter of 9 mm and a length of 20 cm. A healthy test subject was submitted to rectal manometry. The experimental data and analysis of linearity, hysteresis errors, temperature dependence and reproducibility are discussed. The sensor probe extends classical anorectal manometry, in particular with regard to the diagnosis of rectal motility disorders.

  18. Dynamic measurement of temperature using neutron resonance spectroscopy (NRS)

    Energy Technology Data Exchange (ETDEWEB)

    Funk, D.J.; Asay, B.W.; Bennett, B.I.; Bowman, J.D.; Boat, R.M.; Dickson, P.M.; Henson, B.F.; Hull, L.M.; Idar, D.J.; Laabs, G.W.; London, R.K.; Mace, J.L.; Morgan, G.L.; Murk, D.M.; Rabie, R.L.; Ragan, C.E.; Stacy, H.L.; Yuan, V.W. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    1998-07-01

    Accurate temperature measurements in dynamic systems have been pursued for decades and have usually relied on optical techniques. These approaches are generally hampered by insufficient information regarding the emissivity of the system under study. We are developing NRS techniques to measure temperature in dynamic systems and overcome these limitations. Many neutron resonances have narrow intrinsic Breit-Wigner widths such that the resonance is substantially broadened by the atomic motion even at room temperature. Thus, accurate measurement of the Doppler contribution allows one to infer the material temperature, and for the conditions achieved using standard high explosives, the probe itself is not perturbed by the high temperature and pressure. Experiments are conducted using a pulsed spallation source at LANSCE with time-of-flight measurement of the neutron spectra. In initial experiments, we have demonstrated that measurements with ten percent accuracy are possible. We have fielded dynamic tests, most of which were neutron-flux limited. An overview of the approach and the status of our experimental campaign are discussed. {copyright} {ital 1998 American Institute of Physics.}

  19. Effects of environmental parameters and irrigation on the turgor pressure of banana plants measured using the non-invasive, online monitoring leaf patch clamp pressure probe.

    Science.gov (United States)

    Zimmermann, U; Rüger, S; Shapira, O; Westhoff, M; Wegner, L H; Reuss, R; Gessner, P; Zimmermann, G; Israeli, Y; Zhou, A; Schwartz, A; Bamberg, E; Zimmermann, D

    2010-05-01

    Turgor pressure provides a sensitive indicator for irrigation scheduling. Leaf turgor pressure of Musa acuminate was measured by using the so-called leaf patch clamp pressure probe, i.e. by application of an external, magnetically generated and constantly retained clamp pressure to a leaf patch and determination of the attenuated output pressure P(p) that is highly correlated with the turgor pressure. Real-time recording of P(p) values was made using wireless telemetric transmitters, which send the data to a receiver base station where data are logged and transferred to a GPRS modem linked to an Internet server. Probes functioned over several months under field and laboratory conditions without damage to the leaf patch. Measurements showed that the magnetic-based probe could monitor very sensitively changes in turgor pressure induced by changes in microclimate (temperature, relative humidity, irradiation and wind) and irrigation. Irrigation effects could clearly be distinguished from environmental effects. Interestingly, oscillations in stomatal aperture, which occurred frequently below turgor pressures of 100 kPa towards noon at high transpiration or at high wind speed, were reflected in the P(p) values. The period of pressure oscillations was comparable with the period of oscillations in transpiration and photosynthesis. Multiple probe readings on individual leaves and/or on several leaves over the entire height of the plants further emphasised the great impact of this non-invasive turgor pressure sensor system for elucidating the dynamics of short- and long-distance water transport in higher plants.

  20. On the Dynamic Measurements of Hydraulic Characteristics

    Science.gov (United States)

    Hasmatuchi, Vlad; Bosioc, Alin; Münch-Alligné, Cécile

    2016-11-01

    The present work introduces the implementation and validation of a faster method to measure experimentally the efficiency characteristics of hydraulic turbomachines at a model scale on a test rig. The case study is represented by a laboratory prototype of an in-line axial microturbine for water supply networks. The 2.65 kW one-stage variable speed turbine, composed by one upstream 5-blade runner followed by one counter-rotating downstream 7-blade runner, has been installed on the HES-SO Valais/Wallis universal test rig dedicated to assess performances of small hydraulic machinery following the IEC standard recommendations. In addition to the existing acquisition/control system of the test rig used to measure the 3D hill-chart of a turbine by classical static point-by-point method, a second digitizer has been added to acquire synchronized dynamic signals of the employed sensors. The optimal acceleration/deceleration ramps of the electrical drives have been previously identified in order to cope with the purpose of a reduced measurement time while avoiding errors and hysteresis on the acquired hydraulic characteristics. Finally, the comparison between the turbine efficiency hill-charts obtained by dynamic and static point-by-point methods shows a very good agreement in terms of precision and repeatability. Moreover, the applied dynamic method reduces significantly (by a factor of up to ten) the time necessary to measure the efficiency characteristics on model testing.

  1. Cryogenic tunnel measurement of total temperature and pressure

    Science.gov (United States)

    Ng, W.-F.; Rosson, J. C.

    1986-01-01

    A newly developed, 3-mm-diam, dual hot-wire aspirating probe was used to measure the time-resolved stagnation temperature and pressure in a transonic cryogenic wind tunnel. Measurements were taken in the freestream of the settling chamber and test section. Data were also obtained in the unsteady wake shed from an airfoil oscillating at 5 Hz. The investigation revealed the presence of large fluctuations in the settling chamber occuring at the blade passing frequency of the driving fan of the tunnel. These fluctuations decrease at the test section. The rms value of the fluctuating stagnation pressure decreased from 17.5 percent in the settling chamber to 3.7 percent in the test section. Fluctuating stagnation temperature decreased from 12.3 percent to 8.4 percent. Measurements in the wake of the oscillating airfoil showed a fluctuating stagnation temperature of as much as 42 K in rms value.

  2. Sound field separation with sound pressure and particle velocity measurements

    DEFF Research Database (Denmark)

    Fernandez Grande, Efren; Jacobsen, Finn; Leclère, Quentin

    2012-01-01

    separation techniques make it possible to distinguish between outgoing and incoming waves from the two sides, and thus NAH can be applied. In this paper, a separation method based on the measurement of the particle velocity in two layers and another method based on the measurement of the pressure...... and the velocity in a single layer are proposed. The two methods use an equivalent source formulation with separate transfer matrices for the outgoing and incoming waves, so that the sound from the two sides of the array can be modeled independently. A weighting scheme is proposed to account for the distance...... pressure-velocity method, although it requires an additional measurement surface. On the whole, the separation methods can be useful when the disturbance of the incoming field is significant. Otherwise the direct reconstruction is more accurate and straightforward. © 2012 Acoustical Society of America....

  3. Interpretation of Strain Measurements on Nuclear Pressure Vessels

    DEFF Research Database (Denmark)

    Andersen, Svend Ib Smidt; Engbæk, Preben

    1980-01-01

    Selected results from strain measurements on four nuclear pressure vessels are presented and discussed. The measurements were made in several different regions of the vessels: transition zones in vessel heads, flanges and bottom parts, nozzles, internal vessel structure and flange bolts. The resu......Selected results from strain measurements on four nuclear pressure vessels are presented and discussed. The measurements were made in several different regions of the vessels: transition zones in vessel heads, flanges and bottom parts, nozzles, internal vessel structure and flange bolts....... The results presented are based on data obtained by approximately 700 strain-gauges, and a comprehensive knowledge of the quality obtained by such measurements is established. It is shown that a thorough control procedure before and after the test as well as a detailed knowledge of the behaviour of the signal...... with a negligible zeroshift. However, deviations from linear behaviour are observed in several cases. This nonlinearity can be explained by friction (flange connections) or by gaps (concentrical nozzles) in certain regions, whereas local plastic deformations during the first pressure loadings of the vessel seem...

  4. Interferometer for measuring dynamic corneal topography

    Science.gov (United States)

    Micali, Jason Daniel

    The cornea is the anterior most surface of the eye and plays a critical role in vision. A thin fluid layer, the tear film, coats the outer surface of the cornea and serves to protect, nourish, and lubricate the cornea. At the same time, the tear film is responsible for creating a smooth continuous surface where the majority of refraction takes place in the eye. A significant component of vision quality is determined by the shape of the cornea and stability of the tear film. It is desirable to possess an instrument that can measure the corneal shape and tear film surface with the same accuracy and resolution that is currently performed on common optical elements. A dual interferometer system for measuring the dynamic corneal topography is designed, built, and verified. The completed system is validated by testing on human subjects. The system consists of two co-aligned polarization splitting Twyman-Green interferometers designed to measure phase instantaneously. The primary interferometer measures the surface of the tear film while the secondary interferometer simultaneously tracks the absolute position of the cornea. Eye motion, ocular variation, and a dynamic tear film surface will result in a non-null configuration of the surface with respect to the interferometer system. A non-null test results in significant interferometer induced errors that add to the measured phase. New algorithms are developed to recover the absolute surface topography of the tear film and corneal surface from the simultaneous interferometer measurements. The results are high-resolution and high-accuracy surface topography measurements of the in vivo cornea that are captured at standard camera frame rates. This dissertation will cover the development and construction of an interferometer system for measuring the dynamic corneal topography of the human eye. The discussion starts with the completion of an interferometer for measuring the tear film. The tear film interferometer is part of an

  5. Ambient-pressure thermodynamic measurements on UGe{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Hardy, Frederic; Loehneysen, Hilbert von [Forschungszentrum Karlsruhe (Germany). Institut fuer Festkoerperphysik; Physikalisches Institut, Universitaet Karlsruhe (Germany); Meingast, Christoph [Forschungszentrum Karlsruhe (Germany). Institut fuer Festkoerperphysik; Flouquet, Jacques; Huxley, Andrew [SPSMS-DRFMC, CEA-Grenoble (France); Lashley, Jason [Materials Science Division and Technology Division, LANL, Los Alamos, New Mexico (United States); Fisher, Robert A.; Phillips, Norman E. [Materials Science Division, LBNL, Berkeley, California (United States)

    2008-07-01

    The pairing interaction leading to the formation of the Cooper pairs remains unidentified in the ferromagnetic superconductor UGe{sub 2}. Nevertheless, there is strong experimental evidence that superconductivity is not mediated by the magnetic fluctuations that drive T{sub Curie}(p) to zero; it rather appears closely related to another phase boundary T{sub x}(p) that occurs at lower pressure. Theoretical works suggested that this additional phase boundary could arise either from a coupling between SDW and CDW orderings or from a peak in the electronic density of states. Although the existence of this anomaly is experimentally incontestable between 0.6 and 1.2 GPa, the situation at ambient pressure remains ambiguous. We discuss the aforementioned scenarios in the light of recent high-resolution thermal expansion and calorimetric measurements realized under high magnetic fields at ambient pressure.

  6. Ambient-pressure thermodynamic measurements on UGe2

    Science.gov (United States)

    Hardy, F.; Meingast, C.; von Loehneysen, H.; Flouquet, J.; Huxley, A.; Lashley, J.; Fisher, R. A.; Phillips, N. E.

    2008-03-01

    The pairing interaction leading to the formation of the Cooper pairs remains unidentified in the ferromagnetic superconductor UGe2. Nevertheless, there is strong experimental evidence that superconductivity is not mediated by the magnetic fluctuations that drive TCurie (p) to zero; it rather appears closely related to another phase boundary Tx (p) that occurs at lower pressure. Theoretical works suggested that this additional phase boundary could arise either from a coupling between SDW and CDW orderings or from a peak in the electronic density of states. Although the existence of this anomaly is experimentally incontestable between 0.6 and 1.2 GPa, the situation at ambient pressure remains ambiguous. We discuss the aforementioned scenarios in the light of recent high-resolution thermal expansion and calorimetric measurements realized under high magnetic fields at ambient pressure.

  7. Application of PIV-based pressure measurements to the study of aquatic propulsion

    Science.gov (United States)

    Lucas, Kelsey; Dabiri, John; Lauder, George

    2015-11-01

    Although it is relatively straightforward to image how fluid moves around a swimmer, translation of these motions to mechanisms that generate forces for propulsion is more difficult. This process is greatly facilitated by a recently developed technique for non-invasive pressure measurements that generate 2D pressure fields. Here, we explore how accurate a purely pressure-based calculation of propulsive forces can be. By comparing these calculations to forces and torques measured directly using a sensor on a robotic flapping foil system, we characterize the effects of motion frequency and out-of-plane flows on the calculation's accuracy. We then apply this calculation to study the dynamics of fish-like swimming of a foil model with non-uniform flexural stiffness, and to those of a freely swimming fish.

  8. Measurement of Dynamic Light Scattering Intensity in Gels

    CERN Document Server

    Rochas, Cyrille

    2015-01-01

    In the scientific literature little attention has been given to the use of dynamic light scattering (DLS) as a tool for extracting the thermodynamic information contained in the absolute intensity of light scattered by gels. In this article we show that DLS yields reliable measurements of the intensity of light scattered by the thermodynamic fluctuations, not only in aqueous polymer solutions, but also in hydrogels. In hydrogels, light scattered by osmotic fluctuations is heterodyned by that from static or slowly varying inhomogeneities. The two components are separable owing to their different time scales, giving good experimental agreement with macroscopic measurements of the osmotic pressure. DLS measurements in gels are, however, tributary to depolarised light scattering from the network as well as to multiple light scattering. The paper examines these effects, as well as the instrumental corrections required to determine the osmotic modulus. For guest polymers trapped in a hydrogel the measured intensity...

  9. Measurement of thermoelectric, galvanomagnetic, and thermomagnetic effects at ultrahigh pressure

    Science.gov (United States)

    Ovsyannikov, Sergey V.; Shchennikov, Vladimir V.

    2003-04-01

    Lead chalcogenides are successfully applied at sensors of infrared radiation, thermoelectrical devices, thermogenerator, photoresistances, photodiodes, lasers, tensometers etc. Under high pressures above 2.5 - 6 GPa lead chaclogenides are known to suffer phase transitions, but up to now the thermoelectric properties of these materials at high pressure were unknown. In recent papers it was shown that heterophase state of material, which is being forming in the vicinity of semiconductor-metal phase transformations may be considered as a model of layer fabricated systems. As the most properties being dependent on the concentration and configuration of phases inclusions these materials may be used in engineering. For example, semiconductor-metal phase transitions induced by nanosecond heating and cooling of small regions of the memory cell are known to be using for nonvolatile memory develop. Recently the new technique of thermomagnetic measurements allowing to test a micro-samples of semiconductors have been developed at high pressure up to 30 GPa. The technique was applied for determination of scattering mechanisms and mobilities of charge carriers of direct-gap semiconductors Te, Se at ultrahigh pressure up to 30 GPa. The above measurements seems to be perspective for implementation to microelectronic manufacturing and MEMS technologies, for example, in modeling, quality control or testing of integrated circuit (IC). In present paper the thermo- and galvanomagnetic properties of micro-samples ~ 200×200×20 mkm of lead chalcogenides (PbS, PbSe, PbTe) at high pressure are investigated. The data of transverse magnetoresistance (MR) and also transverse and longitudinal Nernst-Ettingshausen (N-E) effects of lead chalcogenides both for initial and new phases, and also for heterophase states in the vicinity of phase transformations at high pressure are presented. One may suppose that the effects observed will find an interesting applications in thermosense industry. The

  10. Dynamic Electrochemical Measurement of Chloride Ions.

    Science.gov (United States)

    Abbas, Yawar; de Graaf, Derk B; Olthuis, Wouter; van den Berg, Albert

    2016-02-05

    This protocol describes the dynamic measurement of chloride ions using the transition time of a silver silver chloride (Ag/AgCl) electrode. Silver silver chloride electrode is used extensively for potentiometric measurement of chloride ions concentration in electrolyte. In this measurement, long-term and continuous monitoring is limited due to the inherent drift and the requirement of a stable reference electrode. We utilized the chronopotentiometric approach to minimize drift and avoid the use of a conventional reference electrode. A galvanostatic pulse is applied to an Ag/AgCl electrode which initiates a faradic reaction depleting the Cl- ions near the electrode surface. The transition time, which is the time to completely deplete the ions near the electrode surface, is a function of the ion concentration, given by the Nernst equation. The square root of the transition time is in linear relation to the chloride ion concentration. Drift of the response over two weeks is negligible (59 µM/day) when measuring 1 mM [Cl-]using a current pulse of 10 Am(-2). This is a dynamic measurement where the moment of transition time determines the response and thus is independent of the absolute potential. Any metal wire can be used as a pseudo-reference electrode, making this approach feasible for long-term measurement inside concrete structures.

  11. A new cable truss support system for coal roadways affected by dynamic pressure

    Institute of Scientific and Technical Information of China (English)

    Hong Yan; Fulian He

    2012-01-01

    The support of coal roadways is seriously affected by intense dynamic pressures.This can lead to problems with large deformation of the roof and the two side walls of coal roadways.Rapid convergence of the walls and roof,a high damage rate to the bolts and cables,or even abrupt roof collapse or rib spalling can occur during the service period of these coal roadways.Analyzing the main support measures used in China leads to a proposed new cable truss supporting system.Thorough study of the entire structure shows the superiority of this design for roadways suffering under dynamic pressure.A corresponding mechanical model of the rock surrounding the cable truss system is described in this paper and formulas for calculating pre-tightening forces of the truss cable,and the minimum anchoring forces,were deduced.The new support system was applied to a typical roadway affected by intensive dynamic pressure that is located in the Xinyuan Coal Mine.The results show that the largest subsidence of the roof was 97 mm,the convergence of the two sides was less than 248 mm,and the average depth of the loose,fractured layer was only 6.12 mm.This proves that the new support system is feasible and effective.

  12. Body mass index and blood pressure measurement during pregnancy.

    LENUS (Irish Health Repository)

    Hogan, Jennifer L

    2012-02-01

    OBJECTIVE: The accurate measurement of blood pressure requires the use of a large cuff in subjects with a high mid-arm circumference (MAC). This prospective study examined the need for a large cuff during pregnancy and its correlation with maternal obesity. METHODS: Maternal body mass index (BMI), fat mass, and MAC were measured. RESULTS: Of 179 women studied, 15.6% were obese. With a BMI of level 1 obesity, 44% needed a large cuff and with a BMI of level 2 obesity 100% needed a large cuff. CONCLUSION: All women booking for antenatal care should have their MAC measured to avoid the overdiagnosis of pregnancy hypertension.

  13. The effect of a dynamic PCL brace on patellofemoral compartment pressures in PCL-and PCL/PLC-deficient knees.

    Science.gov (United States)

    Welch, Tyler; Keller, Thomas; Maldonado, Ruben; Metzger, Melodie; Mohr, Karen; Kvitne, Ronald

    2017-12-01

    The natural history of posterior cruciate ligament (PCL) deficiency includes the development of arthrosis in the patellofemoral joint (PFJ). The purpose of this biomechanical study was to evaluate the hypothesis that dynamic bracing reduces PFJ pressures in PCL- and combined PCL/posterolateral corner (PLC)-deficient knees. Controlled Laboratory Study. Eight fresh frozen cadaveric knees with intact cruciate and collateral ligaments were included. PFJ pressures and force were measured using a pressure mapping system via a lateral arthrotomy at knee flexion angles of 30°, 60°, 90°, and 120° in intact, PCL-deficient, and PCL/PLC-deficient knees under a combined quadriceps/hamstrings load of 400 N/200 N. Testing was then repeated in PCL- and PCL/PLC-deficient knees after application of a dynamic PCL brace. Application of a dynamic PCL brace led to a reduction in peak PFJ pressures in PCL-deficient knees. In addition, the brace led to a significant reduction in peak pressures in PCL/PLC-deficient knees at 60°, 90°, and 120° of flexion. Application of the dynamic brace also led to a reduction in total PFJ force across all flexion angles for both PCL- and PCL/PLC-deficient knees. Dynamic bracing reduces PFJ pressures in PCL- and combined PCL/PLC-deficient knees, particularly at high degrees of knee flexion.

  14. Applications of laser based measurements to combustion related fluid dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Klingmann, J.

    1998-12-01

    This thesis is concerned with laser based techniques for the measurement of fluid dynamical properties and their application to combusting flow fields or flow fields related to combustion. As an introduction, the theory of turbulent flow and combustion is shortly presented. An overview of laser based measuring techniques is given. Next, seven papers are included. The main topic of papers 1 and 2 is the measurements of swirling pipe flows with sudden axi-symmetric expansions. These flow fields are related to the flow fields of gas turbine combustors. Measurements and computations using commercial software are compared. Papers 3 and 7 deal with a laser Doppler anemometry based method for the measurement of the turbulent dissipation rate and its application to an axi-symmetric free jet, respectively. The measurements rely on two-point measurements with high spatial resolution. Also three-component one-point measurements are used to obtain the triple velocity correlations. Together these measurements are sufficient to present the energy balance, if pressure effects are neglected. Papers 4, 5 and 6 are concerned with the turbulent flame speed under premixed conditions. Papers 4 and 5 present flame speed measurements from a stationary burner using methane and Danish natural gas. Particle image velocimetry and one- and two-point Laser Doppler anemometry is used to measure flame speed and turbulent quantities, including integral length scales. Paper 7 presents measurements of flame speed and turbulence parameters in a spark ignition engine. Here heat release analyses from pressure measurements are combined with one- and two-point laser Doppler anemometry to analyze influence of turbulence on flame propagation 50 refs, 25 figs

  15. Towards a shock tube method for the dynamic calibration of pressure sensors.

    Science.gov (United States)

    Downes, Stephen; Knott, Andy; Robinson, Ian

    2014-08-28

    In theory, shock tubes provide a pressure change with a very fast rise time and calculable amplitude. This pressure step could provide the basis for the calibration of pressure transducers used in highly dynamic applications. However, conventional metal shock tubes can be expensive, unwieldy and difficult to modify. We describe the development of a 1.4 MPa (maximum pressure) shock tube made from unplasticized polyvinyl chloride pressure tubing which provides a low-cost, light and easily modifiable basis for establishing a method for determining the dynamic characteristics of pressure sensors.

  16. Effect of temperature and pressure on the dynamics of nanoconfined propane

    Energy Technology Data Exchange (ETDEWEB)

    Gautam, Siddharth, E-mail: gautam.25@osu.edu; Liu, Tingting, E-mail: gautam.25@osu.edu; Welch, Susan; Cole, David [School of Earth Sciences, The Ohio State University, 275 Mendenhall Laboratory, 125 S Oval Mall, Columbus, OH 43210 (United States); Rother, Gernot [Geochemistry and Interfacial Science Group, Chemical Science Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Jalarvo, Niina [Jülich Center for Neutron Sciences (JCNS-1), Forschungszentrum Jülich Outstation at Spallation Neutron Source(SNS), Chemical and Engineering Materials Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Mamontov, Eugene [Spallation Neutron Source (SNS), Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

    2014-04-24

    We report the effect of temperature and pressure on the dynamical properties of propane confined in nanoporous silica aerogel studied using quasielastic neutron scattering (QENS). Our results demonstrate that the effect of a change in the pressure dominates over the effect of temperature variation on the dynamics of propane nano-confined in silica aerogel. At low pressures, most of the propane molecules are strongly bound to the pore walls, only a small fraction is mobile. As the pressure is increased, the fraction of mobile molecules increases. A change in the mechanism of motion, from continuous diffusion at low pressures to jump diffusion at higher pressures has also been observed.

  17. Compressive Sensing Based Machine Learning Strategy For Characterizing The Flow Around A Cylinder With Limited Pressure Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Bright, Ido; Lin, Guang; Kutz, Nathan

    2013-12-05

    Compressive sensing is used to determine the flow characteristics around a cylinder (Reynolds number and pressure/flow field) from a sparse number of pressure measurements on the cylinder. Using a supervised machine learning strategy, library elements encoding the dimensionally reduced dynamics are computed for various Reynolds numbers. Convex L1 optimization is then used with a limited number of pressure measurements on the cylinder to reconstruct, or decode, the full pressure field and the resulting flow field around the cylinder. Aside from the highly turbulent regime (large Reynolds number) where only the Reynolds number can be identified, accurate reconstruction of the pressure field and Reynolds number is achieved. The proposed data-driven strategy thus achieves encoding of the fluid dynamics using the L2 norm, and robust decoding (flow field reconstruction) using the sparsity promoting L1 norm.

  18. Molecular Dynamics Simulation of Water Nanodroplets on Silica Surfaces at High Air Pressures

    DEFF Research Database (Denmark)

    Zambrano, Harvey A; Jaffe, Richard Lawrence; Walther, Jens Honore

    2010-01-01

    e.g., nanobubbles. In the present work we study the role of air on the wetting of hydrophilic systems. We conduct molecular dynamics simulations of a water nanodroplet on an amorphous silica surface at different air pressures. The interaction potentials describing the silica, water, and air...... not been reached. Contact angle measurements of droplets on solid surfaces offer useful quantitative measurements of the physiochemical properties of the solid-liquid interface. For hydrophobic systems the properties the solid- liquid interface are now known to be strongly influenced by the presence of air...... are obtained from the literature. The silica surface is modeled by a large 32 ⨯ 32 ⨯ 2 nm amorphous SiO2 structure consisting of 180000 atoms. The water consists of 18000 water molecules surrounded by N2 and O2 air molecules corresponding to air pressures of 0 bar (vacuum), 50 bar, 100 bar and 200 bar. We...

  19. The measured temperature and pressure of EDC37 detonation products

    Science.gov (United States)

    Ferguson, J. W.; Richley, J. C.; Sutton, B. D.; Price, E.; Ota, T. A.

    2017-01-01

    We present the experimentally determined temperature and pressure of the detonation products of EDC37; a HMX based conventional high explosive. These measurements were performed on a series of cylinder tests. The temperature measurements were undertaken at the end of the cylinder with optical fibres observing the bare explosive through a LiF window. The temperature of the products was measured for approximately 2 µs using single colour pyrometry, multicolour pyrometry and also using time integrated optical emission spectroscopy with the results from all three methods being broadly consistent. The peak temperature was found to be ≈ 3600 K dropping to ≈ 2400 K at the end of the measurement window. The spectroscopy was time integrated and showed that the emission spectra can be approximated using a grey body curve between 520 - 800 nm with no emission or absorption lines being observed. The pressure was obtained using an analytical method which requires the velocity of the expanding cylinder wall and the velocity of detonation. The pressure drops from an initial CJ value of ≈ 38 GPa to ≈ 4 GPa after 2 µs.

  20. Surface Pressure Measurements of Atmospheric Tides Using Smartphones

    Science.gov (United States)

    Price, Colin; Maor, Ron

    2017-04-01

    Similar to the oceans, the atmosphere also has tides that are measured in variations of atmospheric pressure. However, unlike the gravitational tides in the oceans, the atmospheric tides are caused primarily in the troposphere and stratosphere when the atmosphere is periodically heated by the sun, due to tropospheric absorption by water vapor and stratospheric absorption by ozone. Due to the forcing being always on the day side of the globe, the tides migrate around the globe following the sun (migrating tides) with a dominant periodicity of 12 hours (and less so at 24 hours). In recent years smartphones have been equipped with sensitive, cheap and reliable pressure sensors that can easily detect these atmospheric tides. By 2020 it is expected that there will be more than 6 billion smartphones globally, each measuring continuously atmospheric pressure at 1Hz temporal resolution. In this presentation we will present some control experiments we have performed with smartphones to monitor atmospheric tides, while also using random pressure data from more than 50,000 daily users via the WeatherSignal application. We conclude that smartphones are a useful tool for studying atmospheric tides on local and global scales.

  1. Staging of liver fibrosis or cirrhosis: The role of hepaticvenous pressure gradient measurement

    Institute of Scientific and Technical Information of China (English)

    Ki Tae Suk; Dong Joon Kim

    2015-01-01

    Liver fibrosis is a common histological change ofchronic liver injury and it is closely related with portalhypertension which is hemodynamic complication ofchronic liver disease. Currently, liver fibrosis has beenknown as a reversible dynamic process in previousliteratures. Although liver biopsy is a gold standardfor assessing the stage of liver fibrosis, it may notcompletely represent the stage of liver fibrosis becauseof sampling error or semi-quantative measurement.Recent evidences suggested that histologic, clinical,hemodynamic, and biologic features are closelyassociated in patients with chronic liver disease. Hepaticvenous pressure gradient (HVPG) measurement has beenknown as a modality to evaluate the portal pressure.The HVPG measurement has been used clinicallyfor fibrosis diagnosis, risk stratification, preoperativescreening for liver resection, monitoring the efficacy ofmedical treatments, and assessing the prognosis of liverfibrosis. Therefore, the HVPG measurement can be usedto monitor areas the chronic liver disease but also otherimportant areas of chronic liver disease.

  2. Optofluidic Temperature and Pressure Measurements with Fiber Bragg Gratings Embedded in Microfluidic Devices

    CERN Document Server

    Cooksey, Gregory A

    2016-01-01

    The integration of photonic sensors into microfluidic devices provides opportunities for dynamic measurement of chemical and physical properties of fluids in very small volumes. We previously reported on the use of commercially available Fiber Bragg Gratings (FBGs) and on-chip silicon waveguides for temperature sensing. In this report, we demonstrate the integration of FBGs into easy-to-fabricate microfluidic devices and report on their sensitivity for temperature and pressure measurement in microliter volumes. These sensors present new routes to measurement in microfluidic applications such as small-volume calorimetry and microflow metrology.

  3. Skin perfusion pressure on the legs measured as the external pressure required for skin reddening after blanching

    DEFF Research Database (Denmark)

    Holstein, P; Nielsen, P.E.; Lund, P

    1980-01-01

    Hg (SD 8.7). As compared to the intra-arterial blood pressure the BTEP was found to lie close to the mean blood pressure in normal subjects as well as in hypertensive subjects. The present data indicate that the skin perfusion pressure on the legs can be measured by the rapid photo-electric technique......The skin perfusion on the calf was measured photo-electrically and by isotope washout technique using external counter pressure by a blood pressure cuff. By the photocell the skin blanching threshold external pressure (BTEP) was recorded on histamine flared red skin. By isotope washout technique...... the skin blood flow cessation external pressure (FCEP) was recorded using intra-dermal [131I-]-antipyrine mixed with histamine in estimating the skin blood flow. The external pressure was measured with an airfilled plastic cushion connected to a mercury manometer. Over a wide range of pressures as obtained...

  4. Unsteady pressure measurements of decelerated swirling flow in a discharge cone at lower runner speeds

    Science.gov (United States)

    Bosioc, A. I.; Muntean, S.; Tanasa, C.; Susan-Resiga, R.; Vékás, L.

    2014-03-01

    The decelerated swirling flow in the draft tube cone of hydraulic turbines (especially turbines with fixed blades) is responsible for self-induced instabilities which generates pressure pulsations that hinder the turbine operation. An experimental test rig was developed in order to investigate the flow instabilities. A new method was implemented to slow down the runner using a magneto rheological brake in order to be extended the flow regimes investigated. As a result, the experimental investigations are performed for 7 operating regimes in order to quantify the flow behaviour from part load operation to overload operation. The unsteady pressure measurements are carried out on 4 levels in the cone. The unsteady pressure measurements on the cone wall consist in quantifying of three aspects: i) the pressure recovery coefficient obtained based on mean pressure provides the energetic assessment on the draft tube cone; ii) the unsteady quantities (dominant amplitude and frequency) are determined revealing the dynamic behaviour; iii) the plunging and rotating components of the pressure pulsation. As a result, this new method helps us to investigate in detail the flow instability for different operating regimes and allows investigating various flow control solutions.

  5. Pre-measurement rest time affects magnitude and reliability of toe pressure measurements.

    Science.gov (United States)

    Chuter, Vivienne Helaine; Casey, Sarah Louise

    2015-06-01

    Toe pressures are used to evaluate lower extremity healing capacity and screen for peripheral arterial disease (PAD). Although toe pressures are commonly used clinically both as an independent measure and in the calculation of the toe-brachial index, the effect of pre-measurement rest duration on the magnitude and reliability of toe pressures is unknown. This study investigated the effect of pre-measurement rest duration on toe pressures. Seventy community-based participants meeting guidelines for PAD screening were recruited. Systolic toe pressures either at the left or right hallux were manually measured using photoplethysmography following 5, 10 and 15 min of rest in a supine horizontal position. Testing was repeated 7-10 days later. A significant drop in toe pressure (3.86 mmHg) occurred between 5 and 10 min (p = 0.001). No significant change occurred between 10 and 15 min. Reliability after 5 min was excellent (intra-class correlation coefficient, ICC = 0.80, 95% CI 0.68-0.89), increasing slightly at 10 and 15 min (ICC = 0.86, 95% CI 0.77-0.92 and ICC = 0.82, 95% CI 0.69-0.89). Toe pressures stabilize after 10 min of rest in a supine horizontal position. Longer periods of pre-measurement rest did not improve reliability significantly.

  6. Indications for portal pressure measurement in chronic liver disease

    DEFF Research Database (Denmark)

    Hobolth, Lise; Bendtsen, Flemming; Møller, Søren

    2012-01-01

    Portal hypertension leads to development of serious complications such as esophageal varices, ascites, renal and cardiovascular dysfunction. The importance of the degree of portal hypertension has been substantiated within recent years. Measurement of the portal pressure is simple and safe...... of HVPG should therefore be considered as a part of the general characterization of patients with portal hypertension in departments assessing and treating this condition....

  7. Measurements and modeling of VLLE at elevated pressures

    DEFF Research Database (Denmark)

    Laursen, Torben

    and pure component calibration. Samples from the different liquid phases in the high-pressure cell is taken using a moveable needle. The systems investigated have been a combination of the components: CO2, N2, di-methyl ether (DME), water, methanol, ethanol and 1-propanol. 41 isotherms have been measured...... containing CO2, while the model has some problems with systems containing N2....

  8. Quality of blood pressure measurement in community health centres.

    Science.gov (United States)

    Sandoya-Olivera, Edgardo; Ferreira-Umpiérrez, Augusto; Machado-González, Federico

    To determine the quality of the blood pressure measurements performed during routine care in community health centres. An observational, cross-sectional study was conducted in 5 private and public health centres in Maldonado, Uruguay, in July-August 2015. The observations were made during the measurements performed by health personnel, using the requirements established by the American Heart Association. An analysis was made on 36 variables that were grouped in categories related to environment, equipment, interrogation, patient, and observer. Statistical analysis was performed using Chi(2) test or Fisher test. Statistical significance was considered to be less than 5% (p<.05). The measurements were made by a registered nurse or nurse in 71% of cases, physician in 20%, and student nurse in 9%. An aneroid sphygmomanometer was used in 89%, and mercury 11%. Satisfactory results were found in variables related to environment (93%), equipment (99%), and patient attitude (82%), and intermediate in the attitudes of the operator (64%), and poor in relation to the interrogation (18%), with the mean of correct variables per measurement being 69%. The main flaws in the procedure were the operator. The measurement of blood pressure is a manoeuvre that healthcare professionals perform thousands of times a year. If the measurement is used for the diagnosis and/or chronic management of arterial hypertension, not systematically applying the established recommendations leads to an inappropriate care of a very significant number of patients. Copyright © 2017 Elsevier España, S.L.U. All rights reserved.

  9. Measurement of viscosity of gaseous mixtures at atmospheric pressure

    Science.gov (United States)

    Singh, J. J.; Mall, G. H.; Chegini, H.

    1986-01-01

    Coefficients of viscosity of various types of gas mixtures, including simulated natural-gas samples, have been measured at atmospheric pressure and room temperature using a modified capillary tube method. Pressure drops across the straight capillary tube section of a thermal mass flowmeter were measured for small, well-defined, volume flow rates for the test gases and for standard air. In this configuration, the flowmeter provides the volumetric flow rates as well as a well-characterized capillary section for differential pressure measurements across it. The coefficients of viscosity of the test gases were calculated using the reported value of 185.6 micro P for the viscosity of air. The coefficients of viscosity for the test mixtures were also calculated using Wilke's approximation of the Chapman-Enskog (C-E) theory. The experimental and calculated values for binary mixtures are in agreement within the reported accuracy of Wilke's approximation of the C-E theory. However, the agreement for multicomponent mixtures is less satisfactory, possible because of the limitations of Wilkes's approximation of the classical dilute-gas state model.

  10. Accuracy of the Omron RX-M, an automated blood pressure measuring device, measuring blood pressure at the wrist, according to a modified British Hypertension Society protocol.

    NARCIS (Netherlands)

    Braam, R.L.; Aslan, B.; Thien, Th.

    2004-01-01

    OBJECTIVE: To determine the accuracy of the Omron RX-M, a device measuring blood pressure oscillometrically at the wrist. METHODS: In 89 subjects (mean age 55+/-14 years) blood pressure measurements at the wrist with the Omron RX-M were compared to sequential blood pressure measurements with a

  11. Geometry optimization for micro-pressure sensor considering dynamic interference.

    Science.gov (United States)

    Yu, Zhongliang; Zhao, Yulong; Li, Lili; Tian, Bian; Li, Cun

    2014-09-01

    Presented is the geometry optimization for piezoresistive absolute micro-pressure sensor. A figure of merit called the performance factor (PF) is defined as a quantitative index to describe the comprehensive performances of a sensor including sensitivity, resonant frequency, and acceleration interference. Three geometries are proposed through introducing islands and sensitive beams into typical flat diaphragm. The stress distributions of sensitive elements are analyzed by finite element method. Multivariate fittings based on ANSYS simulation results are performed to establish the equations about surface stress, deflection, and resonant frequency. Optimization by MATLAB is carried out to determine the dimensions of the geometries. Convex corner undercutting is evaluated. Each PF of the three geometries with the determined dimensions is calculated and compared. Silicon bulk micromachining is utilized to fabricate the prototypes of the sensors. The outputs of the sensors under both static and dynamic conditions are tested. Experimental results demonstrate the rationality of the defined performance factor and reveal that the geometry with quad islands presents the highest PF of 210.947 Hz(1/4). The favorable overall performances enable the sensor more suitable for altimetry.

  12. Dynamic Sublimation Pressure and the Catastrophic Breakup of Comet ISON

    CERN Document Server

    Steckloff, Jordan K; Bowling, Timothy; Melosh, H Jay; Minton, David; Lisse, Carey M; Battams, Karl

    2015-01-01

    Previously proposed mechanisms have difficulty explaining the disruption of Comet C/2012 S1 (ISON) as it approached the Sun. We describe a novel cometary disruption mechanism whereby comet nuclei fragment and disperse through dynamic sublimation pressure, which induces differential stresses within the interior of the nucleus. When these differential stresses exceed its material strength, the nucleus breaks into fragments. We model the sublimation process thermodynamically and propose that it is responsible for the disruption of Comet ISON. We estimate the bulk unconfined crushing strength of Comet ISON's nucleus and the resulting fragments to be 0.5 Pa and 1-9 Pa respectively, assuming typical Jupiter Family Comet (JFC) albedos. However, if Comet ISON has an albedo similar to Pluto, this strength estimate drops to 0.2 Pa for the intact nucleus and 0.6-4 Pa for its fragments. Regardless of assumed albedo, these are similar to previous strength estimates of JFCs. This suggests that, if Comet ISON is representat...

  13. Laser-Based Dynamic Compression of Geological Materials to Ultrahigh Pressures

    Science.gov (United States)

    Duffy, T. S.

    2015-12-01

    Laser-based dynamic compression provides new opportunities to study the structures and properties of geological materials to ultrahigh pressure conditions reaching 1 terapascal and beyond. By controlling the shape and duration of the incident laser pulse, either shock or ramp (shockless) loading can be produced. Samples can be compressed for ~10s of nanoseconds on spatial scales of ~1 millimeter. Diagnostics include velocity interferometry from which the stress-density response of the material can be determined and X-ray diffraction from which lattice-level structural information is obtained. Our experiments are being carried out at a suite of facilities including the Omega Laser (U. of Rochester), Linear Coherent Light Source (LCLS), and National Ignition Facility (Livermore). Using ramp compression we have constrained pressure-density states in a variety of materials including iron, magnesium oxide, and carbon. X-ray diffraction has been used as a diagnostic to probe the B1-B2 phase transition in MgO under both ramp and shock loading to multi-megabar pressures. We have also examined this same phase transition at more modest pressures on sodium chloride at the LCLS, observing both the B1-B2 transition upon compression and its back transformation upon release. X-ray diffraction measurements have also been used to study the melting curves and high-pressure phase stability of transition metals and alloys, including compositions relevant to the cores of Earth and super-Earth planets.

  14. Optical dynamic deformation measurements at translucent materials.

    Science.gov (United States)

    Philipp, Katrin; Koukourakis, Nektarios; Kuschmierz, Robert; Leithold, Christoph; Fischer, Andreas; Czarske, Jürgen

    2015-02-15

    Due to their high stiffness-to-weight ratio, glass fiber-reinforced polymers are an attractive material for rotors, e.g., in the aerospace industry. A fundamental understanding of the material behavior requires non-contact, in-situ dynamic deformation measurements. The high surface speeds and particularly the translucence of the material limit the usability of conventional optical measurement techniques. We demonstrate that the laser Doppler distance sensor provides a powerful and reliable tool for monitoring radial expansion at fast rotating translucent materials. We find that backscattering in material volume does not lead to secondary signals as surface scattering results in degradation of the measurement volume inside the translucent medium. This ensures that the acquired signal contains information of the rotor surface only, as long as the sample surface is rough enough. Dynamic deformation measurements of fast-rotating fiber-reinforced polymer composite rotors with surface speeds of more than 300 m/s underline the potential of the laser Doppler sensor.

  15. A Study of the Fluid-Dynamic Pressure Fields on Compressor Reed Valves.

    Science.gov (United States)

    1985-12-01

    nigher *A pressures. The total pressure ol the reservoir wnicn suppiieo the air was measured on either a lovi-incn mercury manometer or a3 -v)-incn... mercury manometer . This was the same manometer which was used to measure the total pressure of the reservoir. A pressure tap ran from this total

  16. Propagation of radiosonde pressure sensor errors to ozonesonde measurements

    Directory of Open Access Journals (Sweden)

    R. M. Stauffer

    2013-08-01

    Full Text Available Several previous studies highlight pressure (or equivalently, pressure altitude discrepancies between the radiosonde pressure sensor and that derived from a GPS flown with the radiosonde. The offsets vary during the ascent both in absolute and percent pressure differences. To investigate this, a total of 501 radiosonde/ozonesonde launches from the Southern Hemisphere subtropics to northern mid-latitudes are considered, with launches between 2006–2013 from both historical and campaign-based intensive stations. Three types of electrochemical concentration cell (ECC ozonesonde manufacturers (Science Pump Corporation; SPC and ENSCI/Droplet Measurement Technologies; DMT and five series of radiosondes from two manufacturers (International Met Systems: iMet, iMet-P, iMet-S, and Vaisala: RS80 and RS92 are analyzed to determine the magnitude of the pressure offset and the effects these offsets have on the calculation of ECC ozone (O3 mixing ratio profiles (O3MR from the ozonesonde-measured partial pressure. Approximately half of all offsets are > ±0.7 hPa in the free troposphere, with nearly a quarter > ±1.0 hPa at 26 km, where the 1.0 hPa error represents ~5% of the total atmospheric pressure. Pressure offsets have negligible effects on O3MR below 20 km (98% of launches lie within ±5% O3MR error at 20 km. Ozone mixing ratio errors in the 7–15 hPa layer (29–32 km, a region critical for detection of long-term O3 trends, can approach greater than ±10% (>25% of launches that reach 30 km exceed this threshold. Comparisons of total column O3 yield average differences of +1.6 DU (−1.1 to +4.9 DU 10th to 90th percentiles when the O3 is integrated to burst with addition of the McPeters and Labow (2012 above-burst O3 column climatology. Total column differences are reduced to an average of +0.1 DU (−1.1 to +2.2 DU when the O3 profile is integrated to 10 hPa with subsequent addition of the O3 climatology above 10 hPa. The RS92 radiosondes are clearly

  17. Rapid, optical measurement of the atmospheric pressure on a fast research aircraft using open-path TDLAS

    Directory of Open Access Journals (Sweden)

    B. Buchholz

    2014-05-01

    Full Text Available Because of the high travel speed, the complex flow dynamics around an aircraft and the complex dependency of the fluid dynamics on numerous airborne parameters, it is quite difficult to obtain accurate pressure values at a specific instrument location of an aircraft's fuselage. Complex simulations using computational fluid dynamics (CFD models can in theory computationally "transfer" pressure values from one location to another. However, for long flight patterns, this process is inconvenient and cumbersome. Furthermore these CFD transfer models require a local experimental validation, which is rarely available. In this paper, we describe an integrated approach for a spectroscopic, calibration-free, in-flight pressure determination in an open-path White cell on an aircraft fuselage using ambient, atmospheric water vapour as the "sensor species". The presented measurements are realized with the HAI (Hygrometer for Atmospheric Investigations instrument, built for multiphase water detection via calibration-free TDLAS (tunable diode laser absorption spectroscopy. The pressure determination is based on raw data used for H2O concentration measurement, but with a different post-flight evaluation method, and can therefore be conducted at deferred time intervals on any desired flight track. The spectroscopic pressure is compared in-flight with the static ambient pressure of the aircraft avionic system and a micro-mechanical pressure sensor, located next to the open-path cell, over a pressure range from 150 hPa to 800 hPa, and a water vapour concentration range of more than three orders of magnitude. The correlation between the micro-mechanical pressure sensor measurements and the spectroscopic pressure measurements show an average deviation from linearity of only 0.14% and a small offset of 9.5 hPa. For the spectroscopic pressure evaluation we derive measurement uncertainties under laboratory conditions of 3.2% and 5.1% during in flight operation on the

  18. Rapid, optical measurement of the atmospheric pressure on a fast research aircraft using open-path TDLAS

    Science.gov (United States)

    Buchholz, B.; Afchine, A.; Ebert, V.

    2014-11-01

    Because of the high travel speed, the complex flow dynamics around an aircraft, and the complex dependency of the fluid dynamics on numerous airborne parameters, it is quite difficult to obtain accurate pressure values at a specific instrument location of an aircraft's fuselage. Complex simulations using computational fluid dynamics (CFD) models can in theory computationally "transfer" pressure values from one location to another. However, for long flight patterns, this process is inconvenient and cumbersome. Furthermore, these CFD transfer models require a local experimental validation, which is rarely available. In this paper, we describe an integrated approach for a spectroscopic, calibration-free, in-flight pressure determination in an open-path White cell on an aircraft fuselage using ambient, atmospheric water vapour as the "sensor species". The presented measurements are realised with the HAI (Hygrometer for Atmospheric Investigations) instrument, built for multiphase water detection via calibration-free TDLAS (tunable diode laser absorption spectroscopy). The pressure determination is based on raw data used for H2O concentration measurement, but with a different post-flight evaluation method, and can therefore be conducted at deferred time intervals on any desired flight track. The spectroscopic pressure is compared in-flight with the static ambient pressure of the aircraft avionic system and a micro-mechanical pressure sensor, located next to the open-path cell, over a pressure range from 150 to 800 hPa, and a water vapour concentration range of more than 3 orders of magnitude. The correlation between the micro-mechanical pressure sensor measurements and the spectroscopic pressure measurements shows an average deviation from linearity of only 0.14% and a small offset of 9.5 hPa. For the spectroscopic pressure evaluation we derive measurement uncertainties under laboratory conditions of 3.2 and 5.1% during in-flight operation on the HALO airplane. Under

  19. Effect of temperature, pressure, and cosolvents on structural and dynamic properties of the hydration shell of SNase: a molecular dynamics computer simulation study.

    Science.gov (United States)

    Smolin, Nikolai; Winter, Roland

    2008-01-24

    It is now generally agreed that the hydration water and solvational properties play a crucial role in determining the dynamics and hence the functionality of proteins. We present molecular dynamics computer simulation studies on staphylococcal nuclease (SNase) at various temperatures and pressures as well as in different cosolvent solutions containing various concentrations of urea and glycerol. The aim is to provide a molecular level understanding of how different types of cosolvents (chaotropic and kosmotropic) as well as temperature and high hydrostatic pressure modify the structure and dynamics of the hydration water. Taken together, these three intrinsic thermodynamic variables, temperature, pressure, and chemical potential (or activity) of the solvent, are able to influence the stability and function of the protein by protein-solvent dynamic coupling in different ways. A detailed analysis of the structural and dynamical properties of the water and cosolvents at the protein surface (density profile, coordination numbers, hydrogen-bond distribution, average H-bond lifetimes (water-protein and water-water), and average residence time of water in the hydration shell) was carried out, and differences in the structural and dynamical properties of the hydration water in the presence of the different cosolvents and at temperatures between 300 and 400 K and pressures up to 5000 bar are discussed. Furthermore, the results obtained help understand various thermodynamic properties measured for the protein.

  20. Can pyrene probes be used to measure lateral pressure profiles of lipid membranes? Perspective through atomistic simulations

    DEFF Research Database (Denmark)

    Franova, M. D.; Vattulainen, I.; Ollila, O. H. S.

    2014-01-01

    The lateral pressure profile of lipid bilayers has gained a lot of attention, since changes in the pressure profile have been suggested to shift the membrane protein conformational equilibrium. This relation has been mostly studied with theoretical methods, especially with molecular dynamics...... determinant of the excimer/monomer fluorescence ratio. Thus, the results do not support the usage of di-pyr-PC molecules to measure the shape of the lateral pressure profile. We yet discuss how the probes could potentially be exploited to gain qualitative insight of the changes in pressure profile when lipid...... simulations, since established methods to measure the lateral pressure profile experimentally have not been available. The only experiments that have attempted to gauge the lateral pressure profile have been done by using di-pyrenyl-phosphatidylcholine (di-pyr-PC) probes. In these experiments, the excimer...

  1. A user's guide to intra-abdominal pressure measurement.

    LENUS (Irish Health Repository)

    Sugrue, Michael

    2015-01-01

    The intra-abdominal pressure (IAP) measurement is a key to diagnosing and managing critically ill medical and surgical patients. There are an increasing number of techniques that allow us to measure the IAP at the bedside. This paper reviews these techniques. IAP should be measured at end-expiration, with the patient in the supine position and ensuring that there is no abdominal muscle activity. The intravesicular IAP measurement is convenient and considered the gold standard. The level where the mid-axillary line crosses the iliac crest is the recommended zero reference for the transvesicular IAP measurement; moreover, marking this level on the patient increases reproducibility. Protocols for IAP measurement should be developed for each ICU based on the locally available tools and equipment. IAP measurement techniques are safe, reproducible and accurate and do not increase the risk of urinary tract infection. Continuous IAP measurement may offer benefits in specific situations in the future. In conclusion, the IAP measurement is a reliable and essential adjunct to the management of patients at risk of intra-abdominal hypertension.

  2. Feasibility of hydroxyl concentration measurements by laser-saturated fluorescence in high-pressure flames

    Science.gov (United States)

    Carter, Campbell D.; King, Galen B.; Laurendeau, Normand M.; Salmon, J. Thaddeus

    1987-01-01

    The effect of pressure on the laser-saturated fluorescence method for measuring OH concentration in high-pressure flames is studied using calculations for the burned-gas region of a stoichiometric H2-O2 flame at 2000 K. A numerical model of the excitation dynamics of OH is developed to explore the validity of the balanced cross-rate model at higher pressures. It is shown that depopulation of the laser-coupled levels is sensitive to collisions which depopulate v-double-prime (VDP) = 0 and to rate coefficients for rotational transfer in the ground state which are smaller than those in the excited state. In particular, it is shown that the depopulation of VDP = 0, and hence the laser-coupled levels, depends on the probability of electronic quenching to vibrational levels for which VDP is greater than 0 and vibrational relaxation to VDP = 0.

  3. In situ electrical conductivity measurements of H2O under static pressure up to 28 GPa

    Science.gov (United States)

    Liu, Bao; Gao, Yang; Han, Yonghao; Ma, Yanzhang; Gao, Chunxiao

    2016-08-01

    The in situ electrical conductivity measurements on water in both solid state and liquid state were performed under pressure up to 28 GPa and temperature from 77 K to 300 K using a microcircuit fabricated on a diamond anvil cell (DAC). Water chemically ionization mainly contributes to electrical conduction in liquid state, which is in accord with the results obtained under dynamic pressure. Energy band theory of liquid water was used to understand effect of static pressure on electrical conduction of water. The electric conductivity of H2O decreased discontinuously by four orders of magnitude at 0.7-0.96 GPa, indicating water frozen at this P-T condition. Correspondingly, the conduction of H2O in solid state is determined by arrangement and bending of H-bond in ice VI and ice VII. Based on Jaccard theory, we have concluded that the charge carriers of ice are already existing ions and Bjerrum defects.

  4. Dynamic Foot Pressure as a Countermeasure to Muscle Atrophy

    Science.gov (United States)

    Kyparos, A.; Layne, C. S.; Martinez, D. A.; Clarke, M. S. F.; Feeback, D. L.

    2002-01-01

    Mechanical unloading of skeletal muscle (SKM) as a consequence of space flight or ground-based analogues, such as human bedrest and rodent hindlimb suspension (HLS) models, induces SKM atrophy particularly affecting the anti-gravity musculature of the lower limbs. In the context of manned space flight, the subsequent loss of muscle strength and functionality will pose operational implications jeopardizing mission success. Exercise, currently the primary muscle degradation countermeasure, has not proven completely effective in preventing muscle atrophy. It is therefore imperative that some other forms of in- flight countermeasure be also developed to supplement the prescribed exercise regimen the astronauts follow during spaceflight. Previous work in both humans and rats has shown that mechanical stimulation of the soles of the feet increases neuromuscular activation in the lower limb musculature and that such stimulation results in the limited prevention of atrophy in the soleus muscle of unloaded rats. This study was designed to investigate the effect of cutaneous mechanoreceptor stimulation on hindlimb unloading- induced SKM atrophy in rats. It was hypothesized that mechanical stimulation of the plantar surface of the rat foot during hindlimb suspension (HLS), utilizing a novel stimulation paradigm known as Dynamic Foot Pressure (DFP), would attenuate unloading-induced SKM atrophy. Mature adult male Wistar rats were randomly assigned to four groups of 10 rats each as follows: sedentary controls (Ctrl), hindlimb suspended only (HLS), hindlimb suspended wearing an inflatable boot (HLS-IFL) and hindlimb suspended rats wearing a non-inflatable boot (HLS-NIFL). The stimulation of mechanoreceptors was achieved by applying pressure to the plantar surface of the foot during the 10-day period of HLS using a custom-built boot. The anti-atrophic effects of DFP application was quantified directly by morphological (muscle wet weight, myofiber cross-sectional area

  5. Measurement of cricoid pressure force during simulated Sellick's manoeuvre.

    Science.gov (United States)

    Andruszkiewicz, Paweł; Zawadka, Mateusz; Kosińska, Anna; Walczak-Wieteska, Paulina; Majerowicz, Kalina

    2017-09-27

    Cricoid pressure is a standard anaesthetic procedure used to reduce the risk of aspiration of gastric contents during the induction of general anaesthesia. However, for several years its validity has been questioned. There still remains the question of whether we perform it correctly. The aim of the study was an evaluation of the theoretical knowledge of Sellick's manoeuvre, as well an assessment of practical skill related with it when simulated on a model of the upper airway. The study was performed on a cohort of anaesthetists and anaesthetic nurses working in various hospitals in the Warsaw area. Measurements were taken on an upper airway model placed on an electronic kitchen scale. Participants were asked to perform Sellick's manoeuvre in the way they do it in their clinical practice. The test was done twice. Both the position and pressures applied on the model were documented. Knowledge concerning current recommendations of cricoid force was noted. 206 subjects participated in the study. Only 49% (n = 101) properly identified cricoid cartilage during their application of Sellick's manoeuvre. Application of the correct pressure on the model of the airway was noted in 16.5% (n = 34) during the first attempt and in 20.4% (n = 42) during the second attempt. The median force applied during simulated Sellick's manoeuvrewas 36 N (IQR: 26-55) in the first attempt, and 38 (IQR 25-55) in the second attempt. Sellick's manoeuvre was performed incorrectly in many cases. Half of the participants of our study applied the pressure in the wrong place while the majority of them used an inappropriate amount of force. Thus, the application of cricoid pressure in patients should be preceded with simulation training.

  6. Effect of the shape of mouth pressure variation on dynamic oscillation threshold of a clarinet model

    CERN Document Server

    Bergeot, Baptiste; Vergez, Christophe

    2014-01-01

    Simple models of clarinet instruments based on iterated maps have been used in the past to successfully estimate the threshold of oscillation of this instrument as a function of a constant blowing pressure. However, when the blowing pressure gradually increases through time, the oscillations appear at a much higher value, called dynamic oscillation threshold, than what is predicted in the static case. This is known as bifurcation delay, a phenomenon studied in [1,2] for a clarinet model. In particular the dynamic oscillation threshold is predicted analytically when the blowing pressure is linearly increased. However, the mouth pressure cannot grow indefinitely. During a note attack, after an increasing phase, the musician stabilizes the mouth pressure. In the present work, the analytical prediction of the dynamic oscillation threshold is extended to a situations in which the mouth pressure approaches a steady state pressure according to an exponential time profile. The predictions still show a good agreement ...

  7. Ab-initio molecular dynamics simulation on nano-system under external pressure

    Institute of Scientific and Technical Information of China (English)

    JI; Min; SUN; Deyan; GONG; Xingao

    2004-01-01

    A new constant-pressure molecular dynamics (MD) method is developed to simulate the dynamic behavior and structure transition of finite system under external pressure. In this method, no artificial parameter is introduced and the computation overheads are very small. As an application, a hard-soft transition of single wall carbon nanotube (SWCNT) under external pressure is found, which is in agreement with the experiments.

  8. A batch fabricated capacitive pressure sensor with an integrated Guyton capsule for interstitial fluid pressure measurement

    Science.gov (United States)

    Maleki, Teimour; Fogle, Benjamin; Ziaie, Babak

    2011-05-01

    In this paper, we present the design, fabrication and test of a batch fabricated capacitive pressure sensor with an integrated Guyton capsule for interstitial fluid pressure measurement. The sensor is composed of 12 µm thick single crystalline silicon membrane and a 3 µm gap, hermetically sealed through silicon-glass anodic bonding. A novel batch scale method for creating electrical feed-throughs inside the sealed capacitor chamber is developed. The Guyton capsule consists of an array of 10 µm diameter access holes etched onto a silicon back-plate separated from the silicon sensing membrane by a gap of 5 µm. The presence of the Guyton capsule (i.e. plates with access holes plus the gap separating them from the sensing membrane) allows for the ingress of interstitial fluid inside the 5 µm gap following the implantation, thus, providing an accurate measurement of interstitial fluid pressure. The fabricated sensor is 3 × 2 × 0.42 mm3 in dimensions and has a maximum sensitivity of 10 fF mmHg-1.

  9. HIGH TEMPERATURE HIGH PRESSURE THERMODYNAMIC MEASUREMENTS FOR COAL MODEL COMPOUNDS

    Energy Technology Data Exchange (ETDEWEB)

    Vinayak N. Kabadi

    2000-05-01

    The flow VLE apparatus designed and built for a previous project was upgraded and recalibrated for data measurements for this project. The modifications include better and more accurate sampling technique, addition of a digital recorder to monitor temperature and pressure inside the VLE cell, and a new technique for remote sensing of the liquid level in the cell. VLE data measurements for three binary systems, tetralin-quinoline, benzene--ethylbenzene and ethylbenzene--quinoline, have been completed. The temperature ranges of data measurements were 325 C to 370 C for the first system, 180 C to 300 C for the second system, and 225 C to 380 C for the third system. The smoothed data were found to be fairly well behaved when subjected to thermodynamic consistency tests. SETARAM C-80 calorimeter was used for incremental enthalpy and heat capacity measurements for benzene--ethylbenzene binary liquid mixtures. Data were measured from 30 C to 285 C for liquid mixtures covering the entire composition range. An apparatus has been designed for simultaneous measurement of excess volume and incremental enthalpy of liquid mixtures at temperatures from 30 C to 300 C. The apparatus has been tested and is ready for data measurements. A flow apparatus for measurement of heat of mixing of liquid mixtures at high temperatures has also been designed, and is currently being tested and calibrated.

  10. Nonlinear fractal dynamics of human colonic pressure activity based upon the box-counting method.

    Science.gov (United States)

    Yan, Rongguo; Guo, Xudong

    2013-01-01

    The computational fractal dimension of human colonic pressure activity acquired by a telemetric capsule robot under normal physiological conditions was studied using the box-counting method. The fractal dimension is a numeric value that quantifies to measure how rough the signal is from nonlinear dynamics, rather than its amplitude or other linear statistical features. The colonic pressure activities from the healthy subject during three typical periods were analysed. The results showed that the activity might be fractal with a non-integer fractal dimension after it being integrated over time using the cumsum method, which was never revealed before. Moreover, the activity (after it being integrated) acquired soon after wakening up was the roughest (also the most complex one) with the largest fractal dimension, closely followed by that acquired during sleep with that acquired long time after awakening up (in the daytime) ranking third with the smallest fractal dimension. Fractal estimation might provide a new method to learn the nonlinear dynamics of human gastrointestinal pressure recordings.

  11. High Pressure Sensing and Dynamics Using High Speed Fiber Bragg Grating Interrogation Systems

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, G. [LANL; Sandberg, R. L. [LANL; Lalone, B. M. [NSTec; Marshall, B. R. [NSTec; Grover, M. [NSTec; Stevens, G. D. [NSTec; Udd, E. [Columbia Gorge Research

    2014-06-01

    Fiber Bragg gratings (FBGs) are developing into useful sensing tools for measuring high pressure dynamics in extreme environments under shock loading conditions. Approaches using traditional diode array coupled FBG interrogation systems are often limited to readout speeds in the sub-MHz range. For shock wave physics, required detection speeds approaching 100 MHz are desired. We explore the use of two types of FBG sensing systems that are aimed at applying this technology as embedded high pressure probes for transient shock events. Both approaches measure time resolved spectral shifts in the return light from short (few mm long) uniform FBGs at 1550 nm. In the first approach, we use a fiber coupled spectrometer to demultiplex spectral channels into an array (up to 12) of single element InGaAs photoreceivers. By monitoring the detectors during a shock impact event with high speed recording, we are able to track the pressure induced spectral shifting in FBG down to a time resolution of 20 ns. In the second approach, developed at the Special Technologies Lab, a coherent mode-locked fiber laser is used to illuminate the FBG sensor. After the sensor, wavelength-to-time mapping is accomplished with a chromatic dispersive element, and entire spectra are sampled using a single detector at the modelocked laser repetition rate of 50 MHz. By sampling with a 12 GHz InGaAs detector, direct wavelength mapping in time is recorded, and the pressure induced FBG spectral shift is sampled at 50 MHz. Here, the sensing systems are used to monitor the spectral shifts of FBGs that are immersed into liquid water and shock compressed using explosives. In this configuration, the gratings survive to pressures approaching 50 kbar. We describe both approaches and present the measured spectral shifts from the shock experiments.

  12. Fabrication and Structural Design of Micro Pressure Sensors for Tire Pressure Measurement Systems (TPMS).

    Science.gov (United States)

    Tian, Bian; Zhao, Yulong; Jiang, Zhuangde; Zhang, Ling; Liao, Nansheng; Liu, Yuanhao; Meng, Chao

    2009-01-01

    In this paper we describe the design and testing of a micro piezoresistive pressure sensor for a Tire Pressure Measurement System (TPMS) which has the advantages of a minimized structure, high sensitivity, linearity and accuracy. Through analysis of the stress distribution of the diaphragm using the ANSYS software, a model of the structure was established. The fabrication on a single silicon substrate utilizes the technologies of anisotropic chemical etching and packaging through glass anodic bonding. The performance of this type of piezoresistive sensor, including size, sensitivity, and long-term stability, were investigated. The results indicate that the accuracy is 0.5% FS, therefore this design meets the requirements for a TPMS, and not only has a smaller size and simplicity of preparation, but also has high sensitivity and accuracy.

  13. Fabrication and Structural Design of Micro Pressure Sensors for Tire Pressure Measurement Systems (TPMS

    Directory of Open Access Journals (Sweden)

    Bian Tian

    2009-02-01

    Full Text Available In this paper we describe the design and testing of a micro piezoresistive pressure sensor for a Tire Pressure Measurement System (TPMS which has the advantages of a minimized structure, high sensitivity, linearity and accuracy. Through analysis of the stress distribution of the diaphragm using the ANSYS software, a model of the structure was established. The fabrication on a single silicon substrate utilizes the technologies of anisotropic chemical etching and packaging through glass anodic bonding. The performance of this type of piezoresistive sensor, including size, sensitivity, and long-term stability, were investigated. The results indicate that the accuracy is 0.5% FS, therefore this design meets the requirements for a TPMS, and not only has a smaller size and simplicity of preparation, but also has high sensitivity and accuracy.

  14. Response of transonic diffuser flows to abrupt increases of back pressure: Wall pressure measurements

    Science.gov (United States)

    Bogar, T. J.; Sajben, M.

    1986-10-01

    The propagation of compression pulses in a supercritically operated transonic diffuser was investigated by use of pressure measurements along the top wall of the model. The pulses were generated at the downstream end of the diffuser by the abrupt injection of a secondary flow of air. Two types of waves were observed: (1) an upstream-traveling acoustic wave and (2) a downstream-traveling convective wave which resulted from the impingement of the acoustic wave on the shock. Wave speeds were determined for a range of diffuser pressure ratios including separated, strong-shock flows and fully attached, weak-shock flows. Streamwise distributions of initial and reflected pulse amplitudes were determined for one weak and one strong-shock case over a 3-to-1 range of initial pulse strengths.

  15. Unsteady surface pressure measurements on a slender delta wing undergoing limit cycle wing rock

    Science.gov (United States)

    Arena, Andrew S., Jr.; Nelson, Robert C.

    1991-01-01

    An experimental investigation of slender wing limit cycle motion known as wing rock was investigated using two unique experimental systems. Dynamic roll moment measurements and visualization data on the leading edge vortices were obtained using a free to roll apparatus that incorporates an airbearing spindle. In addition, both static and unsteady surface pressure data was measured on the top and bottom surfaces of the model. To obtain the unsteady surface pressure data a new computer controller drive system was developed to accurately reproduce the free to roll time history motions. The data from these experiments include, roll angle time histories, vortex trajectory data on the position of the vortices relative to the model's surface, and surface pressure measurements as a function of roll angle when the model is stationary or undergoing a wing rock motion. The roll time history data was numerically differentiated to determine the dynamic roll moment coefficient. An analysis of these data revealed that the primary mechanism for the limit cycle behavior was a time lag in the position of the vortices normal to the wing surface.

  16. Patients' experiences and opinions of home blood pressure measurement.

    Science.gov (United States)

    Rickerby, J; Woodward, J

    2003-07-01

    Regular measurement of the blood pressure (BP) is necessary to monitor the treatment of hypertension, and self-measurement is one technique of obtaining such measurements. The aim of this study was to investigate the experiences of individuals who have carried out home BP measurement. A qualitative method using semistructured interviews was used with 13 subjects. These were adults with hypertension who had previous experience of measuring their own BP, and were recruited to the study from one UK general medical practice. Interviews were recorded and transcribed, and data from the interviews have been analysed using phenomenological principles and identifying 'meaning units.' The findings suggest that participants were willing to carry out home measurements and several were pleased to have been asked to be more involved in their own management. All found the technique straightforward. Most noted marked variability in the day-to-day BP measurements. Several exhibited the 'white coat' phenomenon (spuriously raised BP in certain settings only). Some participants showed considerable know-ledge of hypertension and its consequences. They reported being aware of their own BP level and whether this was within acceptable limits. They also reported being willing to take further measurements, and to consider adjusting their treatment in the light of these measurements. Other participants showed less knowledge and enthusiasm, and considered the management of hypertension to be the doctor's job. The findings suggest that for some individuals home BP measurement is acceptable. They also help to explain why, for some individuals, it is not. Using the findings, a number of changes to current practice could be made, which might make home measurements more acceptable and easier to perform. As a result, a new proforma for use in everyday practice has been designed. The study shows that there is considerable scope for sharing BP measurement and management decisions in hypertension with

  17. Relationship between muscle stress and intramuscular pressure during dynamic muscle contractions.

    Science.gov (United States)

    Ward, Samuel R; Davis, Jennifer; Kaufman, Kenton R; Lieber, Richard L

    2007-09-01

    Intramuscular pressure (IMP) has been used to estimate muscle stress indirectly. However, the ability of this technique to estimate muscle stress under dynamic conditions is poorly characterized. Therefore, the purpose of this study was to determine the extent to which IMP is a valid surrogate for muscle stress during dynamic contractions. IMP and muscle stress were compared under steady-state isotonic conditions and during complex dynamic length changes. During concentric contractions the shape of the IMP-velocity curve mimicked the basic shape of the force-velocity curve but with much higher variability. For eccentric contractions, a precipitous drop in IMP was observed despite increased muscle stress. The dissociation between muscle stress and IMP during dynamic contractions was partially explained by sensor movement. When the muscle was not moving, IMP explained 89% +/- 5% of the variance in muscle force. However, when transducer movement occurred the linear relationship between IMP and stress was no longer observed. These findings demonstrate the difficulty in interpreting IMP under dynamic conditions when sensor movement occurs. They also illustrate the need to control transducer movement if muscle stress is to be inferred from IMP measurements such as might be desired during clinical gait testing.

  18. Dynamics of linear maps of idempotent measures

    CERN Document Server

    Rozikov, U A

    2012-01-01

    We describe all linear operators which maps $n-1$-dimensional simplex of idempotent measures to itself. Such operators divided to two classes: the first class contains all $n\\times n$-matrices with non-negative entries which has at least one zero-row; the second class contains all $n\\times n$-matrices with non-negative entries which in each row and in each column has exactly one non-zero entry. These matrices play a role of the stochastic matrices in case of idempotent matrices. For both classes of linear maps we find fixed points. We also study the dynamical systems generated by the linear maps of the set of idempotent measures.

  19. Atomic Quadrupole Moment Measurement Using Dynamic Decoupling.

    Science.gov (United States)

    Shaniv, R; Akerman, N; Ozeri, R

    2016-04-01

    We present a method that uses dynamic decoupling of a multilevel quantum probe to distinguish small frequency shifts that depend on m_{j}^{2}, where m_{j}^{2} is the angular momentum of level |j⟩ along the quantization axis, from large noisy shifts that are linear in m_{j}, such as those due to magnetic field noise. Using this method we measured the electric-quadrupole moment of the 4D_{5/2} level in ^{88}Sr^{+} to be 2.973_{-0.033}^{+0.026}ea_{0}^{2}. Our measurement improves the uncertainty of this value by an order of magnitude and thus helps mitigate an important systematic uncertainty in ^{88}Sr^{+} based optical atomic clocks and verifies complicated many-body quantum calculations.

  20. Urethral pressure reflectometry. A method for simultaneous measurements of pressure and cross-sectional area in the female urethra

    DEFF Research Database (Denmark)

    Klarskov, Niels

    2012-01-01

    A novel technique for simultaneous measurements of pressure and cross-sectional area (CA) in the female urethra, denoted Urethral Pressure Reflectometry (UPR), was devised. A very thin and highly flexible polyurethane-bag was placed in the urethra. A pump applied increasing and decreasing pressur...

  1. Noninvasive Intracranial Volume and Pressure Measurements Using Ultrasound

    Science.gov (United States)

    Hargens, A. R.

    1998-01-01

    Prevention of secondary brain injuries following head can be accomplished most easily when intracranial pressure (ICP) is monitored. However, current measurement techniques are invasive and thus not practical in the combat environment. The Pulsed Phase Lock Loop (PPLL) devise, which was developed and patented, uses a unique, noninvasive ultrasonic phase comparison method to measure slight changes in cranial volume which occur with changes in ICP. Year one studies involved instrument improvements and measurement of altered intracranial distance with altered ICP in fresh cadavera. Our software was improved to facilitate future studies of normal subjects and trauma patients. Our bench studies proved that PPLL output correlated highly with changes in path length across a model cranium. Cadaveric studies demonstrated excellent compact, noninvasive devise for monitoring changes in intracranial distance may aid in the early detection of elevated ICP, decreasing risk of secondary brain injury and infection, and returning head-injured patients to duty.

  2. Measuring mitotic spindle dynamics in budding yeast

    Science.gov (United States)

    Plumb, Kemp

    In order to carry out its life cycle and produce viable progeny through cell division, a cell must successfully coordinate and execute a number of complex processes with high fidelity, in an environment dominated by thermal noise. One important example of such a process is the assembly and positioning of the mitotic spindle prior to chromosome segregation. The mitotic spindle is a modular structure composed of two spindle pole bodies, separated in space and spanned by filamentous proteins called microtubules, along which the genetic material of the cell is held. The spindle is responsible for alignment and subsequent segregation of chromosomes into two equal parts; proper spindle positioning and timing ensure that genetic material is appropriately divided amongst mother and daughter cells. In this thesis, I describe fluorescence confocal microscopy and automated image analysis algorithms, which I have used to observe and analyze the real space dynamics of the mitotic spindle in budding yeast. The software can locate structures in three spatial dimensions and track their movement in time. By selecting fluorescent proteins which specifically label the spindle poles and cell periphery, mitotic spindle dynamics have been measured in a coordinate system relevant to the cell division. I describe how I have characterised the accuracy and precision of the algorithms by simulating fluorescence data for both spindle poles and the budding yeast cell surface. In this thesis I also describe the construction of a microfluidic apparatus that allows for the measurement of long time-scale dynamics of individual cells and the development of a cell population. The tools developed in this thesis work will facilitate in-depth quantitative analysis of the non-equilibrium processes in living cells.

  3. Dynamic Runner Forces and Pressure Fluctuations on the Draft Tube Wall of a Model Pump-Turbine

    Science.gov (United States)

    Kirschner, O.; Ruprecht, A.; Göde, E.; Riedelbauch, S.

    2016-11-01

    When Francis-turbines and pump-turbines operate at off-design conditions, typically a vortex rope develops. The vortex rope causes pressure oscillations leading to fluctuations of the forces affecting the runner. The presence of dynamic runner forces over a long period of time might damage the bearings and possibly the runner. In this experimental investigation, the fluctuating part of the runner forces and the pressure oscillations on the draft tube wall were measured on a model pump-turbine with a simplified straight cone draft tube in different operating conditions. The investigation focuses on the correlation of the pressure fluctuations frequency measured at the draft tube wall with the frequency of the fluctuating forces on the runner. The comparison between pressure fluctuations and dynamic forces shows a significant correlation in all operating points. For the comparison of different components in the spatial directions of the forces, the pressure fluctuations were separated in a synchronous part and a rotating part for operating points with higher amplitudes. The rotating pressure fluctuations correlate with the radial forces especially in the operating points with a rotating vortex rope. At frequencies with higher amplitudes in the pressure fluctuations caused by the vortex rope movement, there are also higher amplitudes in the radial forces at the same frequencies.

  4. Step Prediction During Perturbed Standing Using Center Of Pressure Measurements

    Directory of Open Access Journals (Sweden)

    Milos R. Popovic

    2007-04-01

    Full Text Available The development of a sensor that can measure balance during quiet standing and predict stepping response in the event of perturbation has many clinically relevant applica- tions, including closed-loop control of a neuroprothesis for standing. This study investigated the feasibility of an algorithm that can predict in real-time when an able-bodied individual who is quietly standing will have to make a step to compensate for an external perturbation. Anterior and posterior perturbations were performed on 16 able-bodied subjects using a pul- ley system with a dropped weight. A linear relationship was found between the peak center of pressure (COP velocity and the peak COP displacement caused by the perturbation. This result suggests that one can predict when a person will have to make a step based on COP velocity measurements alone. Another important feature of this finding is that the peak COP velocity occurs considerably before the peak COP displacement. As a result, one can predict if a subject will have to make a step in response to a perturbation sufficiently ahead of the time when the subject is actually forced to make the step. The proposed instability detection algorithm will be implemented in a sensor system using insole sheets in shoes with minitur- ized pressure sensors by which the COPv can be continuously measured. The sensor system will be integrated in a closed-loop feedback system with a neuroprosthesis for standing in the near future.

  5. Simulations of piezoelectric pressure sensor for radial artery pulse measurement

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, Abhay B. [Department of Electronic Science, University of Pune, Pune 411 007 (India); Kalange, Ashok E. [Department of Electronic Science, University of Pune, Pune 411 007 (India); Tuljaram Chaturchand College, Baramati 413 102 (India); Bodas, Dhananjay, E-mail: dhananjay.bodas@gmail.co [Center for Nanobio Sciences, Agharkar Research Institute, Pune 411 004 (India); Gangal, S.A. [Department of Electronic Science, University of Pune, Pune 411 007 (India)

    2010-04-15

    A radial artery pulse is used to diagnose human body constitution (Prakruti) in Ayurveda. A system consisting of piezoelectric sensor (22 mm x 12 mm), data acquisition card and LabView software was used to record the pulse data. The pulse obtained from the sensor was noisy, even though signal processing was done. Moreover due to large sized senor accurate measurements were not possible. Hence, a need was felt to develop a sensor of the size of the order of finger tip with a resonant frequency of the order of 1 Hz. A micromachined pressure sensor based on piezoelectric sensing mechanism was designed and simulated using CoventorWare. Simulations were carried out by varying dimensions of the sensor to optimize the resonant frequency, stresses and voltage generated as a function of applied pressure. All simulations were done with pressure ranging of 1-30 kPa, which is the range used by Ayurvedic practitioners for diagnosis. Preliminary work on fabrication of such a sensor was carried out successfully.

  6. A Procedure for Measuring Microplastics using Pressurized Fluid Extraction.

    Science.gov (United States)

    Fuller, Stephen; Gautam, Anil

    2016-06-07

    A method based on pressurized fluid extraction (PFE) was developed for measuring microplastics in environmental samples. This method can address some limitations of the current microplastic methods and provide laboratories with a simple analytical method for quantifying common microplastics in a range of environmental samples. The method was initially developed by recovering 101% to 111% of spiked plastics on glass beads and was then applied to a composted municipal waste sample with spike recoveries ranging from 85% to 94%. The results from municipal waste samples and soil samples collected from an industrial area demonstrated that the method is a promising alternative for determining the concentration and identity of microplastics in environmental samples.

  7. How to measure intraocular pressure: Schiötz tonometry

    Directory of Open Access Journals (Sweden)

    Sue Stevens

    2008-06-01

    Full Text Available If glaucoma is diagnosed early, treatment can then be given that may preserve vision. Although raised intraocular pressure (IOP is not the only sign of glaucoma, the IOP should be checked routinely on all adults attending eye care facilities. Applanation tonometry (as described in Issue 64, December 2007 is the most accurate method to measure IOP, but Schiötz tonometry is also a useful screening test. If Schiötz tonometry reveals a high IOP, this result should be checked and confirmed by applanation tonometry and the patient referred to the senior clinician at the eye clinic.

  8. Real-time measurement of phloem turgor pressure in Hevea brasiliensis with a modified cell pressure probe

    OpenAIRE

    An, Feng; Cahill, David; Rookes, James; Lin, Weifu; Kong, Lingxue

    2014-01-01

    Background Although the pressure flow theory is widely accepted for the transport of photoassimilates in phloem sieve elements, it still requires strong experimental validation. One reason for that is the lack of a precise method for measuring the real-time phloem turgor pressure from the sink tissues, especially in tree trunks. Results Taking the merits of Hevea brasiliensis, a novel phloem turgor pressure probe based on the state of the art cell pressure probe was developed. Our field measu...

  9. Medical students and measuring blood pressure: Results from the American Medical Association Blood Pressure Check Challenge.

    Science.gov (United States)

    Rakotz, Michael K; Townsend, Raymond R; Yang, Jianing; Alpert, Bruce S; Heneghan, Kathleen A; Wynia, Matthew; Wozniak, Gregory D

    2017-06-01

    Blood pressure (BP) measurement is the most common procedure performed in clinical practice. Accurate BP measurement is critical if patient care is to be delivered with the highest quality, as stressed in published guidelines. Physician training in BP measurement is often limited to a brief demonstration during medical school without retraining in residency, fellowship, or clinical practice to maintain skills. One hundred fifty-nine students from medical schools in 37 states attending the American Medical Association's House of Delegates Meeting in June 2015 were assessed on an 11-element skillset on BP measurement. Only one student demonstrated proficiency on all 11 skills. The mean number of elements performed properly was 4.1. The findings suggest that changes in medical school curriculum emphasizing BP measurement are needed for medical students to become, and remain, proficient in BP measurement. Measuring BP correctly should be taught and reinforced throughout medical school, residency, and the entire career of clinicians. © 2017 American Medical Association. Journal of Clinical Hypertension published by Wiley Periodicals, Inc.

  10. High pressure studies on structural and secondary relaxation dynamics in silyl derivative of D-glucose

    Science.gov (United States)

    Minecka, Aldona; Kamińska, Ewa; Tarnacka, Magdalena; Dzienia, Andrzej; Madejczyk, Olga; Waliłko, Patrycja; Kasprzycka, Anna; Kamiński, Kamil; Paluch, Marian

    2017-08-01

    In this paper, broadband dielectric spectroscopy was applied to investigate molecular dynamics of 1,2,3,4,6-penta-O-(trimethylsilyl)-D-glucopyranose (S-GLU) at ambient and elevated pressures. Our studies showed that apart from the structural relaxation, one well resolved asymmetric secondary process (initially labeled as β) is observed in the spectra measured at p = 0.1 MPa. Analysis with the use of the coupling model and criterion proposed by Ngai and Capaccioli indicated that the β-process in S-GLU is probably a Johari-Goldstein relaxation of intermolecular origin. Further high pressure experiments demonstrated that there are in fact two secondary processes contributing to the β-relaxation. Therefore, one can postulate that the coupling model is a necessary, but not sufficient criterion to identify the true nature of the given secondary relaxation process. The role of pressure experiments in better understanding of the molecular origin of local mobility seems to be much more important. Interestingly, our research also revealed that the structural relaxation in S-GLU is very sensitive to compression. It was reflected in an extremely high pressure coefficient of the glass transition temperature (dTg/dp = 412 K/GPa). According to the literature data, such a high value of dTg/dp has not been obtained so far for any H-bonded, van der Waals, or polymeric glass-formers.

  11. Testing substellar models with dynamical mass measurements

    Directory of Open Access Journals (Sweden)

    Liu M.C.

    2011-07-01

    Full Text Available We have been using Keck laser guide star adaptive optics to monitor the orbits of ultracool binaries, providing dynamical masses at lower luminosities and temperatures than previously available and enabling strong tests of theoretical models. We have identified three specific problems with theory: (1 We find that model color–magnitude diagrams cannot be reliably used to infer masses as they do not accurately reproduce the colors of ultracool dwarfs of known mass. (2 Effective temperatures inferred from evolutionary model radii are typically inconsistent with temperatures derived from fitting atmospheric models to observed spectra by 100–300 K. (3 For the only known pair of field brown dwarfs with a precise mass (3% and age determination (≈25%, the measured luminosities are ~2–3× higher than predicted by model cooling rates (i.e., masses inferred from Lbol and age are 20–30% larger than measured. To make progress in understanding the observed discrepancies, more mass measurements spanning a wide range of luminosity, temperature, and age are needed, along with more accurate age determinations (e.g., via asteroseismology for primary stars with brown dwarf binary companions. Also, resolved optical and infrared spectroscopy are needed to measure lithium depletion and to characterize the atmospheres of binary components in order to better assess model deficiencies.

  12. Wall pressure measurements of flooding in vertical countercurrent annular air–water flow

    Energy Technology Data Exchange (ETDEWEB)

    Choutapalli, I., Vierow, K.

    2010-01-01

    An experimental study of flooding in countercurrent air-water annular flow in a large diameter vertical tube using wall pressure measurements is described in this paper. Axial pressure profiles along the length of the test section were measured up to and after flooding using fast response pressure transducers for three representative liquid flow rates representing a wide range of liquid Reynolds numbers (ReL = 4Γ/μ; Γ is the liquid mass flow rate per unit perimeter; μ is the dynamic viscosity) from 3341 to 19,048. The results show that flooding in large diameter tubes cannot be initiated near the air outlet and is only initiated near the air inlet. Fourier analysis of the wall pressure measurements shows that up to the point of flooding, there is no dominant wave frequency but rather a band of frequencies encompassing both the low frequency and the broad band that are responsible for flooding. The data indicates that flooding in large diameter vertical tubes may be caused by the constructive superposition of a plurality of waves rather than the action of a single large-amplitude wave.

  13. Dynamic neurotransmitter interactions measured with PET

    Energy Technology Data Exchange (ETDEWEB)

    Schiffer, W.K.; Dewey, S.L.

    2001-04-02

    Positron emission tomography (PET) has become a valuable interdisciplinary tool for understanding physiological, biochemical and pharmacological functions at a molecular level in living humans, whether in a healthy or diseased state. The utility of tracing chemical activity through the body transcends the fields of cardiology, oncology, neurology and psychiatry. In this, PET techniques span radiochemistry and radiopharmaceutical development to instrumentation, image analysis, anatomy and modeling. PET has made substantial contributions in each of these fields by providing a,venue for mapping dynamic functions of healthy and unhealthy human anatomy. As diverse as the disciplines it bridges, PET has provided insight into an equally significant variety of psychiatric disorders. Using the unique quantitative ability of PET, researchers are now better able to non-invasively characterize normally occurring neurotransmitter interactions in the brain. With the knowledge that these interactions provide the fundamental basis for brain response, many investigators have recently focused their efforts on an examination of the communication between these chemicals in both healthy volunteers and individuals suffering from diseases classically defined as neurotransmitter specific in nature. In addition, PET can measure the biochemical dynamics of acute and sustained drug abuse. Thus, PET studies of neurotransmitter interactions enable investigators to describe a multitude of specific functional interactions in the human brain. This information can then be applied to understanding side effects that occur in response to acute and chronic drug therapy, and to designing new drugs that target multiple systems as opposed to single receptor types. Knowledge derived from PET studies can be applied to drug discovery, research and development (for review, see (Fowler et al., 1999) and (Burns et al., 1999)). Here, we will cover the most substantial contributions of PET to understanding

  14. The study of measuring technology on the dynamic mechanical properties of welded joint with high strain rate

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In this paper, to meet the needs of studying work of dynamic mechanical properties of welded joint, the dynamic mechanical properties of welded joint were measured by means of SHPB(Split Hopkinson Pressure Bar).The dynamic mechanical property's curves of every part of welded joint were obtained. For studying the dynamic behavior of mechanical heterogeneity of welded joint, important data were offered. The method of test creates a new way of studying dynamic mechanical properties of welded joint.

  15. Novel Method for Processing the Dynamic Calibration Signal of Pressure Sensor

    Directory of Open Access Journals (Sweden)

    Zhongyu Wang

    2015-07-01

    Full Text Available Dynamic calibration is one of the important ways to acquire the dynamic performance parameters of a pressure sensor. This research focuses on the processing method for the output of calibrated pressure sensor, and mainly attempts to solve the problem of extracting the true information of step response under strong interference noise. A dynamic calibration system based on a shock tube is established to excite the time-domain response signal of a calibrated pressure sensor. A key processing on difference modeling is applied for the obtained signal, and several generating sequences are established. A fusion process for the generating sequences is then undertaken, and the true information of the step response of the calibrated pressure sensor can be obtained. Finally, by implementing the common QR decomposition method to deal with the true information, a dynamic model characterizing the dynamic performance of the calibrated pressure sensor is established. A typical pressure sensor was used to perform calibration tests and a frequency-domain experiment for the sensor was also conducted. Results show that the proposed method could effectively filter strong interference noise in the output of the sensor and the corresponding dynamic model could effectively characterize the dynamic performance of the pressure sensor.

  16. Novel Method for Processing the Dynamic Calibration Signal of Pressure Sensor.

    Science.gov (United States)

    Wang, Zhongyu; Li, Qiang; Wang, Zhuoran; Yan, Hu

    2015-07-21

    Dynamic calibration is one of the important ways to acquire the dynamic performance parameters of a pressure sensor. This research focuses on the processing method for the output of calibrated pressure sensor, and mainly attempts to solve the problem of extracting the true information of step response under strong interference noise. A dynamic calibration system based on a shock tube is established to excite the time-domain response signal of a calibrated pressure sensor. A key processing on difference modeling is applied for the obtained signal, and several generating sequences are established. A fusion process for the generating sequences is then undertaken, and the true information of the step response of the calibrated pressure sensor can be obtained. Finally, by implementing the common QR decomposition method to deal with the true information, a dynamic model characterizing the dynamic performance of the calibrated pressure sensor is established. A typical pressure sensor was used to perform calibration tests and a frequency-domain experiment for the sensor was also conducted. Results show that the proposed method could effectively filter strong interference noise in the output of the sensor and the corresponding dynamic model could effectively characterize the dynamic performance of the pressure sensor.

  17. Measurement component technology. Volume 1: Cryogenic pressure measurement technology, high pressure flange seals, hydrogen embrittlement of pressure transducer material, close coupled versus remote transducer installation and temperature compensation of pressure transducers

    Science.gov (United States)

    Hayakawa, K. K.; Udell, D. R.; Iwata, M. M.; Lytle, C. F.; Chrisco, R. M.; Greenough, C. S.; Walling, J. A.

    1972-01-01

    The results are presented of an investigation into the availability and performance capability of measurement components in the area of cryogenic temperature, pressure, flow and liquid detection components and high temperature strain gages. In addition, technical subjects allied to the components were researched and discussed. These selected areas of investigation were: (1) high pressure flange seals, (2) hydrogen embrittlement of pressure transducer diaphragms, (3) The effects of close-coupled versus remote transducer installation on pressure measurement, (4) temperature transducer configuration effects on measurements, and (5) techniques in temperature compensation of strain gage pressure transducers. The purpose of the program was to investigate the latest design and application techniques in measurement component technology and to document this information along with recommendations for upgrading measurement component designs for future S-2 derivative applications. Recommendations are provided for upgrading existing state-of-the-art in component design, where required, to satisfy performance requirements of S-2 derivative vehicles.

  18. Derivation of a measure of systolic blood pressure mutability: a novel information theory-based metric from ambulatory blood pressure tests.

    Science.gov (United States)

    Contreras, Danitza J; Vogel, Eugenio E; Saravia, Gonzalo; Stockins, Benjamin

    2016-03-01

    We provide ambulatory blood pressure (BP) exams with tools based on information theory to quantify fluctuations thus increasing the capture of dynamic test components. Data from 515 ambulatory 24-hour BP exams were considered. Average age was 54 years, 54% were women, and 53% were under BP treatment. The average systolic pressure (SP) was 127 ± 8 mm Hg. A data compressor (wlzip) designed to recognize meaningful information is invoked to measure mutability which is a form of dynamical variability. For patients with the same average SP, different mutability values are obtained which reflects the differences in dynamical variability. In unadjusted linear regression models, mutability had low association with the mean systolic BP (R(2) = 0.056; P information toward diagnosis.

  19. Dynamic and quasi-static measurements of C-4 and primasheet P1000 explosives

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Geoffrey W [Los Alamos National Laboratory; Thompson, Darla G [Los Alamos National Laboratory; De Luca, Racci [Los Alamos National Laboratory; Rae, Philip J [Los Alamos National Laboratory; Cady, Carl M [Los Alamos National Laboratory; Todd, Steven N [SNL

    2010-01-01

    We have measured dynamic and quasi-static mechanical properties of C-4 and Primasheet P1000 explosive materials to provide input data for modeling efforts. Primasheet P1000 is a pentaerythritol tetranitrate-based rubberized explosive. C-4 is a RDX-based moldable explosive. Dynamic measurements included acoustic and split-Hopkinson pressure bar tests. Quasi-static testing was done in compression on load frames and on a dynamic mechanical analyzer. Split-Hopkinson and quasi-static tests were done at five temperatures from -50 C to 50 C. Acoustic velocities were measured at, above, and below room temperature.

  20. Quantitative Thermochemical Measurements in High-Pressure Gaseous Combustion

    Science.gov (United States)

    Kojima, Jun J.; Fischer, David G.

    2012-01-01

    We present our strategic experiment and thermochemical analyses on combustion flow using a subframe burst gating (SBG) Raman spectroscopy. This unconventional laser diagnostic technique has promising ability to enhance accuracy of the quantitative scalar measurements in a point-wise single-shot fashion. In the presentation, we briefly describe an experimental methodology that generates transferable calibration standard for the routine implementation of the diagnostics in hydrocarbon flames. The diagnostic technology was applied to simultaneous measurements of temperature and chemical species in a swirl-stabilized turbulent flame with gaseous methane fuel at elevated pressure (17 atm). Statistical analyses of the space-/time-resolved thermochemical data provide insights into the nature of the mixing process and it impact on the subsequent combustion process in the model combustor.

  1. Measurement of Episcleral Venous Pressure in Normal Chinese People

    Institute of Scientific and Technical Information of China (English)

    Yimin Zhong; Dawei Peng

    2000-01-01

    Purpose: To measure episcleral venous pressure (EVP) in normal Chinese people.Methods: EVP was measured in 110 eyes of 74 subjects distributed in seven age groups from 10 to 80 years using episcleral venomanometer (EV-310). The differences in EVP values were analyzed with age and either eye.Results: EVP values of the 110 eyes appeared as normal distribution. The value x ± SD was (9. 11 ± 1.22) mmHg, and the 95% normal value range was 6. 73 mmHg~11.50mmHg. No statistically significant difference of EVP was found in the seven age groups.And there was no statistically significant difference of EVP between the right and left eyes.Conclusions: The value x ± SD of EVP in Chinese normal eyes is 9. 11 mmHg ± 1.22mmHg. The normal value of EVP does not vary with age and either eye.

  2. Development and application of optical fibre strain and pressure sensors for in-flight measurements

    Science.gov (United States)

    Lawson, N. J.; Correia, R.; James, S. W.; Partridge, M.; Staines, S. E.; Gautrey, J. E.; Garry, K. P.; Holt, J. C.; Tatam, R. P.

    2016-10-01

    Fibre optic based sensors are becoming increasingly viable as replacements for traditional flight test sensors. Here we present laboratory, wind tunnel and flight test results of fibre Bragg gratings (FBG) used to measure surface strain and an extrinsic fibre Fabry-Perot interferometric (EFFPI) sensor used to measure unsteady pressure. The calibrated full scale resolution and bandwidth of the FBG and EFFPI sensors were shown to be 0.29% at 2.5 kHz up to 600 μɛ and 0.15% at up to 10 kHz respectively up to 400 Pa. The wind tunnel tests, completed on a 30% scale model, allowed the EFFPI sensor to be developed before incorporation with the FBG system into a Bulldog aerobatic light aircraft. The aircraft was modified and certified based on Certification Standards 23 (CS-23) and flight tested with steady and dynamic manoeuvres. Aerobatic dynamic manoeuvres were performed in flight including a spin over a g-range  -1g to  +4g and demonstrated both the FBG and the EFFPI instruments to have sufficient resolution to analyse the wing strain and fuselage unsteady pressure characteristics. The steady manoeuvres from the EFFPI sensor matched the wind tunnel data to within experimental error while comparisons of the flight test and wind tunnel EFFPI results with a Kulite pressure sensor showed significant discrepancies between the two sets of data, greater than experimental error. This issue is discussed further in the paper.

  3. Dynamical analysis of high-pressure supercritical carbon dioxide jet in well drilling

    Institute of Scientific and Technical Information of China (English)

    DU Yu-kun; WANG Rui-he; NI Hong-jian; HUANG Zhi-yuan; LI Mu-kun

    2013-01-01

    This paper presents the design of an experimental setup and mathematical and physical models to determine the dynamical characteristics of the high-pressure supercritical carbon dioxide (SC-CO2) jet with a highly potential applications in the well drilling.The effects of three major factors on the wellbore dynamical characteristics of the high-pressure SC-CO2 jet,i.e.,the nozzle diameter,the standoff distance and the jet pressure are determined.It is indicated that the pressure of CO2 reduces severely in the SC-CO2 jet impact process.It is also found that the bottom-hole pressure and the temperature increase as the nozzle diameter increases but decrease with the increase of the standoff distance.The higher the jet pressure at the wellbore inlet is,the higher the pressure and the lower the temperature at the bottom-hole will be.

  4. Can foot anthropometric measurements predict dynamic plantar surface contact area?

    Directory of Open Access Journals (Sweden)

    Collins Natalie

    2009-10-01

    Full Text Available Abstract Background Previous studies have suggested that increased plantar surface area, associated with pes planus, is a risk factor for the development of lower extremity overuse injuries. The intent of this study was to determine if a single or combination of foot anthropometric measures could be used to predict plantar surface area. Methods Six foot measurements were collected on 155 subjects (97 females, 58 males, mean age 24.5 ± 3.5 years. The measurements as well as one ratio were entered into a stepwise regression analysis to determine the optimal set of measurements associated with total plantar contact area either including or excluding the toe region. The predicted values were used to calculate plantar surface area and were compared to the actual values obtained dynamically using a pressure sensor platform. Results A three variable model was found to describe the relationship between the foot measures/ratio and total plantar contact area (R2 = 0.77, p R2 = 0.76, p Conclusion The results of this study indicate that the clinician can use a combination of simple, reliable, and time efficient foot anthropometric measurements to explain over 75% of the plantar surface contact area, either including or excluding the toe region.

  5. Laser-Shock Experiments: Calorimetry Measurements to TPa Pressures

    Science.gov (United States)

    Jeanloz, R.

    2012-12-01

    Laser-driven shock experiments are more like calorimetry measurements, characterized by determinations of Hugoniot temperature (TH) as a function of shock velocity (US), rather than the equation-of-state measurements afforded by mechanical-impact experiments. This is because particle velocity (up) is often not accessible to direct measurement in laser-shock experiments, so must be inferred with reference to a material having a well-determined, independently calibrated Hugoniot equation of state (up is obtained from the impact velocity in traditional shock experiments, and the combination of US and up yields the pressure-density equation of state for the sample). Application of a Mie-Grüneisen model shows that the isochoric specific heat for a given phase is: CV = (US - c0)2 {s2US (dTH/dUS) + γ0 c0 s (TH/US)}-1 with US = c0 + s up, and γ0 is the zero-pressure Grüneisen parameter (γ/V = constant is assumed here). This result is a generalization to TH-US variables of the Walsh and Christian (1955) formula for the temperature rise along the Hugoniot of a given phase (identified here with a US - up relation that is locally linear); it can be analytically integrated to give TH(US) in terms of an average value of CV, if no phase transition takes place. Analysis of the TH-US slopes obtained from laser-shock measurements on MgO yields specific-heat values ranging from 1.02 (± 0.05) kJ/kg/K at 320-345 GPa and TH = 7700-9000 K to 1.50 (± 0.05) kJ/kg/K at 350-380 GPa and TH = 8700-9500 K. A fit to the absolute values of TH(US) in this pressure-temperature range gives CV = 1.26 (± 0.10) kJ/kg/K, in good accord with the Dulong-Petit value CV = 1.24 kJ/kg/K.

  6. Blood pressure measurement in children: which method? which is the gold standard.

    Science.gov (United States)

    Vidal, Enrico; Murer, Luisa; Matteucci, Maria Chiara

    2013-01-01

    The burden of hypertension has become increasingly prevalent in children. Hypertension that begins in childhood can carry on into adulthood, therefore early detection, accurate diagnosis and effective therapy of high blood pressure may improve long-term outcomes of children and adolescents. As far as pediatric hypertension is concerned, doubts still persist about the right instruments, modalities and standards of reference that should be used in routine practice. Due to the dynamic process of growth and development, many physiological parameters undergo intensive change with age. Therefore, in children, the definition of hypertension can not rely on a single blood pressure level but should be based on age- and height-specific percentiles. In this review, we introduce the nephrologist to the correct definition of high blood pressure in children. Moreover, we specifically address the main characteristics of different modalities for blood pressure measurement in children, focusing on practical aspects. The latest international guidelines and appropriate standards of reference for office, ambulatory and home blood pressure data collection are presented. As clinicians are being faced with a greater number of children with hypertension, they should be aware of these peculiarities.

  7. Urethral pressure reflectometry. A method for simultaneous measurements of pressure and cross-sectional area in the female urethra

    DEFF Research Database (Denmark)

    Klarskov, Niels

    2012-01-01

    per second. The examinations were performed with the women supine relaxing, supine squeezing, and standing relaxing. The examination provided measures of the opening pressure (the pressure exactly needed to open the urethra), the closing pressure (the pressure where the urethra closes again after......A novel technique for simultaneous measurements of pressure and cross-sectional area (CA) in the female urethra, denoted Urethral Pressure Reflectometry (UPR), was devised. A very thin and highly flexible polyurethane-bag was placed in the urethra. A pump applied increasing and decreasing pressures...... the hysteresis were decreased in stress urinary incontinent (SUI) women compared to continent women. Thus the parameters seem to be relevant regarding SUI. UPR examination was performed before and after urethral bulking and from these examinations a mechanism of action of the bulking procedure was proposed...

  8. Direct intra-abdominal pressure monitoring via piezoresistive pressure measurement: a technical note

    Directory of Open Access Journals (Sweden)

    Dembinski Rolf

    2009-04-01

    Full Text Available Abstract Background Piezoresistive pressure measurement technique (PRM has previously been applied for direct IAP measurement in a porcine model using two different devices. Aim of this clinical study was to assess both devices regarding complications, reliability and agreement with IVP in patients undergoing elective abdominal surgery. Methods A prospective cohort study was performed in 20 patients randomly scheduled to receive PRM either by a Coach®-probe or an Accurate++®-probe (both MIPM, Mammendorf, Germany. Probes were placed on the greater omentum and passed through the abdominal wall paralleling routine drainages. PRM was compared with IVP measurement by t-testing and by calculating mean difference as well as limits of agreement (LA. Results There were no probe related complications. Due to technical limitations, data could be collected in 3/10 patients with Coach® and in 7/10 patients with Accurate++®. Analysis was carried out only for Accurate++®. Mean values did not differ to mean IVP values. Mean difference to IVP was 0.1 ± 2.8 mmHg (LA: -5.5 to 5.6 mmHg. Conclusion Direct IAP measurement was clinically uneventful. Although results of Accurate++® were comparable to IVP, the device might be too fragile for IAP measurements in the clinical setting. Local ethical committee trial registration: EK2024

  9. Direct intra-abdominal pressure monitoring via piezoresistive pressure measurement: a technical note

    Science.gov (United States)

    Otto, Jens; Kaemmer, Daniel; Binnebösel, Marcel; Jansen, Marc; Dembinski, Rolf; Schumpelick, Volker; Schachtrupp, Alexander

    2009-01-01

    Background Piezoresistive pressure measurement technique (PRM) has previously been applied for direct IAP measurement in a porcine model using two different devices. Aim of this clinical study was to assess both devices regarding complications, reliability and agreement with IVP in patients undergoing elective abdominal surgery. Methods A prospective cohort study was performed in 20 patients randomly scheduled to receive PRM either by a Coach®-probe or an Accurate++®-probe (both MIPM, Mammendorf, Germany). Probes were placed on the greater omentum and passed through the abdominal wall paralleling routine drainages. PRM was compared with IVP measurement by t-testing and by calculating mean difference as well as limits of agreement (LA). Results There were no probe related complications. Due to technical limitations, data could be collected in 3/10 patients with Coach® and in 7/10 patients with Accurate++®. Analysis was carried out only for Accurate++®. Mean values did not differ to mean IVP values. Mean difference to IVP was 0.1 ± 2.8 mmHg (LA: -5.5 to 5.6 mmHg). Conclusion Direct IAP measurement was clinically uneventful. Although results of Accurate++® were comparable to IVP, the device might be too fragile for IAP measurements in the clinical setting. Local ethical committee trial registration: EK2024 PMID:19383161

  10. Context-aware patient guidance during blood pressure self-measurement

    DEFF Research Database (Denmark)

    Sandager, Puk; Lindahl, Camilla; Schlütter, Jacob Mørup

    2013-01-01

    The importance of accurate measurement of blood pressure in the screening and management of hypertension during pregnancy is well established. Blood pressure levels can be measured manually by healthcare staff or by using a blood pressure self-measurement device, either at home or in the clinic...... the blood pressure self-measurement process. Preliminary results indicate that such active and context-aware guidance leads to more reliable measurements by inhibiting non-adherent patient behavior...

  11. The value of pressure ulcer risk assessment and interface pressure measurements in patients: A nursing perspective

    NARCIS (Netherlands)

    J.T.M. Weststrate

    2005-01-01

    textabstractPressure sores in an intensive care unit 35 and related variables: a descriptive study Prevalence of pressure ulcers, risk factors 47 and the use of pressure-relieving mattresses in ICU patients The clinical relevance of the Waterlow 61 Pressure Sore Risk Scale in the ICU The r

  12. In situ impedance measurement of microwave atmospheric pressure plasma

    Science.gov (United States)

    Lee, S. T.; Nam, W. J.; Lee, J. K.; Yun, G. S.

    2017-04-01

    The impedance of atmospheric pressure argon plasma jets driven by microwave frequency is determined in situ by a novel ‘two frequency method’. In the conventional method of reflection coefficient ({{S}}11) measurement, the frequency of the driving microwave power is scanned, which inevitably affects the plasma characters and leads to uncertainty in the estimated plasma impedance. In our proposed method, the frequency-scanning signal additional to the driving power is used to measure {{S}}11 over a wide frequency range, which enables accurate determination of the plasma impedance based on an equivalent circuit model. The measured resistance and reactance of the plasma increase with the driving power in agreement with the transmission line theory. Based on this in situ measurement of the plasma impedance, the net power coupled to the plasma has been determined. The overall power efficiency remains approximately unchanged around 45% for different input power levels owing to the competing effects between the impedance mismatch and the volume change of the plasma.

  13. Measuring static and dynamic contact angles using a liquid needle

    Science.gov (United States)

    Sanedrin, Raymond; Jin, Ming; Frese, Daniel; Scheithauer, Carsten; Willers, Thomas

    2016-11-01

    The optical determination of static and advancing contact angle is made on drops applied or extended, respectively, onto a substrate through the use of thin solid needles. Although this method has been used extensively, this method of dosing can be time consuming, cumbersome and if not meticulously performed can lead to erroneous contact angle results. Herein, we present an alternative way of applying drops onto substrates using a small liquid jet, which is produced by a liquid pressure dosing system acting as a "liquid needle." A comparative static contact angle study on 14 different surfaces with two different liquids were performed utilizing two different ways of dosing: the conventional solid and a novel liquid needle based technique. We found, for all but one sample, that the obtained results were highly comparable. Observed differences can be explained by the characteristics of either way of dosing. In addition, we used the liquid pressure based dosing system for optical advancing contact angle measurement on two different samples. The liquid needle based method facilitates the expansion of a drop from 0.1 to 22 μL within less than 1.2 seconds, which provided constant contact angle versus drop base diameter curves. The obtained results were highly comparable with dynamic Wilhelmy contact angle measurements.

  14. Solar wind dynamic pressure and electric field as the main factors controlling Saturn's aurorae.

    Science.gov (United States)

    Crary, F J; Clarke, J T; Dougherty, M K; Hanlon, P G; Hansen, K C; Steinberg, J T; Barraclough, B L; Coates, A J; Gérard, J-C; Grodent, D; Kurth, W S; Mitchell, D G; Rymer, A M; Young, D T

    2005-02-17

    The interaction of the solar wind with Earth's magnetosphere gives rise to the bright polar aurorae and to geomagnetic storms, but the relation between the solar wind and the dynamics of the outer planets' magnetospheres is poorly understood. Jupiter's magnetospheric dynamics and aurorae are dominated by processes internal to the jovian system, whereas Saturn's magnetosphere has generally been considered to have both internal and solar-wind-driven processes. This hypothesis, however, is tentative because of limited simultaneous solar wind and magnetospheric measurements. Here we report solar wind measurements, immediately upstream of Saturn, over a one-month period. When combined with simultaneous ultraviolet imaging we find that, unlike Jupiter, Saturn's aurorae respond strongly to solar wind conditions. But in contrast to Earth, the main controlling factor appears to be solar wind dynamic pressure and electric field, with the orientation of the interplanetary magnetic field playing a much more limited role. Saturn's magnetosphere is, therefore, strongly driven by the solar wind, but the solar wind conditions that drive it differ from those that drive the Earth's magnetosphere.

  15. Circulatory effects of expiratory flow-limited exercise, dynamic hyperinflation and expiratory muscle pressure

    Directory of Open Access Journals (Sweden)

    P. T. Macklem

    2006-12-01

    Full Text Available This article reviews recent research in normal subjects exercising with and without expiratory flow limitation at 1 L·s–1 imposed by a Starling resistor in the expiratory line, and in patients with chronic obstructive pulmonary disease (COPD, using optoelectronic plethysmography to measure respiratory kinematics, combined with mouth, pleural and abdominal pressure measurements, to assess work of breathing and respiratory muscle performance. In normal subjects, flow-limited exercise resulted in the following: 1 Impaired exercise performance due to intolerable dyspnoea; 2 hypercapnia; 3 excessive respiratory muscle recruitment; 4 blood shifts from trunk to extremities; 5 a 10% reduction in cardiac output and a 5% reduction in arterial oxygen saturation, decreasing energy supplies to working respiratory and locomotor muscles. In both normal subjects and in COPD patients, dynamic hyperinflation did not always occur. Those patients that hyperinflated had worse lung function and less work of breathing, but better exercise performance than the others, in whom expiratory muscle recruitment prevented dynamic hyperinflation at the cost of increased work of breathing and excessive oxygen cost of breathing. This established an early competition between respiratory and locomotor muscles for available energy supplies. Dynamic hyperinflation is a better exercise strategy in chronic obstructive pulmonary disease than expiratory muscle recruitment, but the benefit it confers is small.

  16. Argon metastable dynamics in a filamentary jet micro-discharge at atmospheric pressure

    CERN Document Server

    Niermann, B; Kuschel, T; Benedikt, J; Böke, M; Winter, J

    2011-01-01

    Space and time resolved concentrations of Ar ($^{3}P_2$) metastable atoms at the exit of an atmospheric pressure radio-frequency micro-plasma jet were measured using tunable diode laser absorption spectroscopy. The discharge features a coaxial geometry with a hollow capillary as an inner electrode and a ceramic tube with metal ring as outer electrode. Absorption profiles of metastable atoms as well as optical emission measurements reveal the dynamics and the filamentary structure of the discharge. The average spatial distribution of Ar metastables is characterized with and without a target in front of the jet, showing that the target potential and therewith the electric field distribution substantially changes the filaments' expansion. Together with the detailed analysis of the ignition phase and the discharge's behavior under pulsed operation, the results give an insight into the excitation and de-excitation mechanisms.

  17. Experimental measurement of the thermal stability criteria for low pressure methanol synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Berty, J.M.; Lenczyk, J.P.; Shah, S.M.

    1982-11-01

    The mathematical basis was derived for the experimental measurement of the ''Slope Condition'' and of the ''Dynamic Condition'' of the thermal stability criteria in a laboratory-scale internal recycle reactor. This work also resulted in clearer interpretations and simpler expressions for the two stability criteria. The method was experimentally demonstrated on the example of the low pressure methanol synthesis. Only seven experiments were needed to evaluate the stability criteria of this reaction for which the kinetics is unknown.

  18. Stress Rupture Life Reliability Measures for Composite Overwrapped Pressure Vessels

    Science.gov (United States)

    Murthy, Pappu L. N.; Thesken, John C.; Phoenix, S. Leigh; Grimes-Ledesma, Lorie

    2007-01-01

    Composite Overwrapped Pressure Vessels (COPVs) are often used for storing pressurant gases onboard spacecraft. Kevlar (DuPont), glass, carbon and other more recent fibers have all been used as overwraps. Due to the fact that overwraps are subjected to sustained loads for an extended period during a mission, stress rupture failure is a major concern. It is therefore important to ascertain the reliability of these vessels by analysis, since the testing of each flight design cannot be completed on a practical time scale. The present paper examines specifically a Weibull statistics based stress rupture model and considers the various uncertainties associated with the model parameters. The paper also examines several reliability estimate measures that would be of use for the purpose of recertification and for qualifying flight worthiness of these vessels. Specifically, deterministic values for a point estimate, mean estimate and 90/95 percent confidence estimates of the reliability are all examined for a typical flight quality vessel under constant stress. The mean and the 90/95 percent confidence estimates are computed using Monte-Carlo simulation techniques by assuming distribution statistics of model parameters based also on simulation and on the available data, especially the sample sizes represented in the data. The data for the stress rupture model are obtained from the Lawrence Livermore National Laboratories (LLNL) stress rupture testing program, carried out for the past 35 years. Deterministic as well as probabilistic sensitivities are examined.

  19. Dynamic arterial elastance predicts mean arterial pressure decrease associated with decreasing norepinephrine dosage in septic shock.

    Science.gov (United States)

    Guinot, Pierre-Grégoire; Bernard, Eugénie; Levrard, Mélanie; Dupont, Hervé; Lorne, Emmanuel

    2015-01-19

    Gradual reduction of the dosage of norepinephrine (NE) in patients with septic shock is usually left to the physician's discretion. No hemodynamic indicator predictive of the possibility of decreasing the NE dosage is currently available at the bedside. The respiratory pulse pressure variation/respiratory stroke volume variation (dynamic arterial elastance (Eadyn)) ratio has been proposed as an indicator of vascular tone. The purpose of this study was to determine whether Eadyn can be used to predict the decrease in arterial pressure when decreasing the NE dosage in resuscitated sepsis patients. A prospective study was carried out in a university hospital intensive care unit. All consecutive patients with septic shock monitored by PICCO2 for whom the intensive care physician planned to decrease the NE dosage were enrolled. Measurements of hemodynamic and PICCO2 variables were obtained before/after decreasing the NE dosage. Responders were defined by a >15% decrease in mean arterial pressure (MAP). In total, 35 patients were included. MAP decreased by >15% after decreasing the NE dosage in 37% of patients (n = 13). Clinical characteristics appeared to be similar between responders and nonresponders. Eadyn was lower in responders than in nonresponders (0.75 (0.69 to 0.85) versus 1 (0. 83 to 1.22), P decrease in arterial pressure, with an area under the receiver-operating characteristic curve of 0.87 (95% confidence interval (95% CI): 0.72 to 0.96; P decrease in arterial pressure in response to NE dose reduction. Eadyn may constitute an easy-to-use functional approach to arterial-tone assessment, which may be helpful to identify patients likely to benefit from NE dose reduction.

  20. Effect of Nasal Obstruction on Continuous Positive Airway Pressure Treatment: Computational Fluid Dynamics Analyses.

    Directory of Open Access Journals (Sweden)

    Tadashi Wakayama

    Full Text Available Nasal obstruction is a common problem in continuous positive airway pressure (CPAP therapy for obstructive sleep apnea and limits treatment compliance. The purpose of this study is to model the effects of nasal obstruction on airflow parameters under CPAP using computational fluid dynamics (CFD, and to clarify quantitatively the relation between airflow velocity and pressure loss coefficient in subjects with and without nasal obstruction.We conducted an observational cross-sectional study of 16 Japanese adult subjects, of whom 9 had nasal obstruction and 7 did not (control group. Three-dimensional reconstructed models of the nasal cavity and nasopharynx with a CPAP mask fitted to the nostrils were created from each subject's CT scans. The digital models were meshed with tetrahedral cells and stereolithography formats were created. CPAP airflow simulations were conducted using CFD software. Airflow streamlines and velocity contours in the nasal cavities and nasopharynx were compared between groups. Simulation models were confirmed to agree with actual measurements of nasal flow rate and with pressure and flow rate in the CPAP machine.Under 10 cmH2O CPAP, average maximum airflow velocity during inspiration was 17.6 ± 5.6 m/s in the nasal obstruction group but only 11.8 ± 1.4 m/s in the control group. The average pressure drop in the nasopharynx relative to inlet static pressure was 2.44 ± 1.41 cmH2O in the nasal obstruction group but only 1.17 ± 0.29 cmH2O in the control group. The nasal obstruction and control groups were clearly separated by a velocity threshold of 13.5 m/s, and pressure loss coefficient threshold of approximately 10.0. In contrast, there was no significant difference in expiratory pressure in the nasopharynx between the groups.This is the first CFD analysis of the effect of nasal obstruction on CPAP treatment. A strong correlation between the inspiratory pressure loss coefficient and maximum airflow velocity was found.

  1. Prediction of the dynamic oscillation threshold in a clarinet model with a linearly increasing blowing pressure

    CERN Document Server

    Bergeot, Baptiste; Vergez, Christophe; Gazengel, Bruno

    2012-01-01

    Reed instruments are modeled as self-sustained oscillators driven by the pressure inside the mouth of the musician. A set of nonlinear equations connects the control parameters (mouth pressure, lip force) to the system output, hereby considered as the mouthpiece pressure. Clarinets can then be studied as dynamical systems, their steady behavior being dictated uniquely by the values of the control parameters. Considering the resonator as a lossless straight cylinder is a dramatic yet common simplification that allows for simulations using nonlinear iterative maps. In this paper, we investigate analytically the effect of a time-varying blowing pressure on the behavior of this simplified clarinet model. When the control parameter varies, results from the so-called dynamic bifurcation theory are required to properly analyze the system. This study highlights the phenomenon of bifurcation delay and defines a new quantity, the dynamic oscillation threshold. A theoretical estimation of the dynamic oscillation thresho...

  2. Molecular dynamics of liquid SiO2 under high pressure

    Science.gov (United States)

    Rustad, James R.; Yuen, David A.; Spera, Frank J.

    1990-01-01

    The molecular dynamics of pure SiO2 liquids was investigated up to pressures of 20 GPa at 4000 K using 252, 498, 864, and 1371 particles. The results obtained suggest that the pressure-induced maxima in the self-diffusion coefficients of both oxygen and silicon are dependent on the system size. In the case of larger systems, the maximum decreases and shifts to lower pressures. Changes in the velocity autocorrelation function with increasing pressure are described. The populations of anomalously coordinated silicon and oxygen are then discussed as a function of pressure and system size.

  3. Molecular dynamics of liquid SiO2 under high pressure

    Science.gov (United States)

    Rustad, James R.; Yuen, David A.; Spera, Frank J.

    1990-01-01

    The molecular dynamics of pure SiO2 liquids was investigated up to pressures of 20 GPa at 4000 K using 252, 498, 864, and 1371 particles. The results obtained suggest that the pressure-induced maxima in the self-diffusion coefficients of both oxygen and silicon are dependent on the system size. In the case of larger systems, the maximum decreases and shifts to lower pressures. Changes in the velocity autocorrelation function with increasing pressure are described. The populations of anomalously coordinated silicon and oxygen are then discussed as a function of pressure and system size.

  4. Systems and methods for pressure and temperature measurement

    Energy Technology Data Exchange (ETDEWEB)

    Challener, William Albert; Airey, Li

    2016-12-06

    A measurement system in one embodiment includes an acquisition module and a determination module. The acquisition module is configured to acquire resonant frequency information corresponding to a sensor disposed in a remote location from the acquisition module. The resonant frequency information includes first resonant frequency information for a first resonant frequency of the sensor corresponding to environmental conditions of the remote location, and also includes second resonant frequency information for a different, second resonant frequency of the sensor corresponding to the environmental conditions of the remote location. The determination module is configured to use the first resonant frequency information and the second resonant frequency information to determine the temperature and the pressure at the remote location.

  5. Radiation pressure efficiency measurements of nanoparticle coated microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Soo Y. [National Research Council, Research Associateship Programs, 500 Fifth Street NW (Keck 568), Washington, D.C. 20001 (United States); Taylor, Joseph D.; Ladouceur, Harold D.; Hart, Sean J.; Terray, Alex, E-mail: terray@nrl.navy.mil [Naval Research Laboratory, Chemistry Division, Bioanalytical Chemistry, Code 6112, 4555 Overlook Avenue S.W., Washington, D.C. 20375 (United States)

    2013-12-02

    Experimental measurements of the radiation pressure efficiency (Q{sub pr}) for several microparticles have been compared to theoretical calculations extrapolated from the Bohren-Huffman code for Mie scattering of coated particles. An increased shift of the Q{sub pr} parameter was observed for 2 μm SiO{sub 2} core particles coated with nanoparticles of higher refractive indices. Coatings of 14 nm melamine particles were found to increase the Q{sub pr} parameter 135 times over similar coatings using SiO{sub 2} particles of the same size. While a coating of 100 nm polystyrene particles also showed a significant increase, they did not agree well with theoretical values. It is hypothesized that other factors such as increased scatter, drag, and finite coating coverage are no longer negligible for coatings using nanoparticles in this size regime.

  6. Radiation pressure efficiency measurements of nanoparticle coated microspheres

    Science.gov (United States)

    Kim, Soo Y.; Taylor, Joseph D.; Ladouceur, Harold D.; Hart, Sean J.; Terray, Alex

    2013-12-01

    Experimental measurements of the radiation pressure efficiency (Qpr) for several microparticles have been compared to theoretical calculations extrapolated from the Bohren-Huffman code for Mie scattering of coated particles. An increased shift of the Qpr parameter was observed for 2 μm SiO2 core particles coated with nanoparticles of higher refractive indices. Coatings of 14 nm melamine particles were found to increase the Qpr parameter 135 times over similar coatings using SiO2 particles of the same size. While a coating of 100 nm polystyrene particles also showed a significant increase, they did not agree well with theoretical values. It is hypothesized that other factors such as increased scatter, drag, and finite coating coverage are no longer negligible for coatings using nanoparticles in this size regime.

  7. In situ viscosity measurements of albite melt under high pressure

    CERN Document Server

    Funakoshi, K I; Terasaki, H

    2002-01-01

    The viscosities of albite (NaAlSi sub 3 O sub 8) melt under high pressures have been measured using an x-ray radiography falling sphere method with synchrotron radiation. This method has enabled us to determine the precise sinking velocity directly. Recent experiments of albite melt showed the presence of a viscosity minimum around 5 GPa (Poe et al 1997 Science 276 1245, Mori et al 2000 Earth Planet. Sci. Lett. 175 87). We present the results for albite melt up to 5.2 GPa at 1600 and 1700 deg. C. The viscosity minimum is clearly observed to be around 4.5 GPa, and it might be explained not by the change of the compression mechanism in albite melt but by change of the phase itself.

  8. Modelling the Dynamic Interaction Power System Lamp - Application to High Pressure Mercury Gas Discharge Lamps

    Directory of Open Access Journals (Sweden)

    ZIANE, M.

    2007-11-01

    Full Text Available The aim of this paper is to study the dynamic behaviour of a plant constituted by an electrical power system and a gas discharge lamp, this latter, increasingly used in street lighting, remains a nonlinear load element. Various approaches are used to represent it, one is the approximation of the discharge represented by a hot "channel", which verifies the assumption of local thermodynamic equilibrium [LTE] or the polynomial form of the conductance variation. A calculation procedure, based on "channel" approximation of the high pressure mercury (HPM gas-discharge lamp, is developed to determine the physical and electric magnitudes, which characterize the dynamic behavior of the couple "lamp-electrical power system". The evolution of the lamp properties when principal parameters of the discharge (pressure of mercury, voltage supply, frequency are varying were studied and analyzed. We show the concordance between simulation, calculations and measurements for electric, energetic or irradiative characteristics. The model reproduces well the evolution of properties of the supply when principal parameters of the discharge vary.

  9. Non-Invasive Measurement of Pulsatile Intracranial Pressures Using Ultrasound

    Science.gov (United States)

    Ueno, Toshiaki; Ballard, Richard E.; Shuer, Lawrence M.; Cantrell, John H.; Cantrell, John H.; Hargens, Alan R.

    1997-01-01

    Early detection of elevated intracranial pressure (ICP) will aid clinical decision-making for head trauma, brain tumor and other cerebrovascular diseases. Conventional methods, however, require surgical procedures which take time and are accompanied by increased risk of infection. Accordingly we have developed and refined a new ultrasound device to measure skull movements which are known to occur in conjunction with altered ICP. The principle of this device is based upon pulse phase locked loop (PPLL), which enables us to detect changes in distance on the order of microns between an ultrasound transducer on one side of the skull and the opposite inner surface of the cranium. The present study was designed to verify this measurement technique in cadavera. Transcranial distance was increased in steps of 10 mmHg from zero to 50 mmHg by saline infusion into the lateral ventricle of two cadavera. In separate experiments, pulsations of ICP with the amplitudes of zero to 2 mmHg were generated by rhythmic injections of saline using a syringe. When the ICP was stepwise increased from zero to 50 mmHg, transcranial distance increased in proportion with the ICP increase (y=12 x - 76, r=0.938), where y is changes in transcranial distance in microns and x is ICP in mmHg. In the data recorded while ICP pulsations were generated, fast Fourier transform analysis demonstrated that cranial pulsations were clearly associated with ICP pulsations. The results indicate that changes in transcranial distance is linearly correlated with those in ICP, and also that the PPLL device has sufficient sensitivity to detect transcranial pulsations which occur in association with the cardiac cycle. By analyzing the magnitude of cranial pulsations, we may be able to estimate the pressure-volume index in the cranium. As a result, estimates of intracranial compliance may be possible by using the PPLL device. Further studies are necessary in normal subjects and patients.

  10. Non-Invasive Measurement of Pulsatile Intracranial Pressures Using Ultrasound

    Science.gov (United States)

    Ueno, Toshiaki; Ballard, Richard E.; Shuer, Lawrence M.; Cantrell, John H.; Cantrell, John H.; Hargens, Alan R.

    1997-01-01

    Early detection of elevated intracranial pressure (ICP) will aid clinical decision-making for head trauma, brain tumor and other cerebrovascular diseases. Conventional methods, however, require surgical procedures which take time and are accompanied by increased risk of infection. Accordingly we have developed and refined a new ultrasound device to measure skull movements which are known to occur in conjunction with altered ICP. The principle of this device is based upon pulse phase locked loop (PPLL), which enables us to detect changes in distance on the order of microns between an ultrasound transducer on one side of the skull and the opposite inner surface of the cranium. The present study was designed to verify this measurement technique in cadavera. Transcranial distance was increased in steps of 10 mmHg from zero to 50 mmHg by saline infusion into the lateral ventricle of two cadavera. In separate experiments, pulsations of ICP with the amplitudes of zero to 2 mmHg were generated by rhythmic injections of saline using a syringe. When the ICP was stepwise increased from zero to 50 mmHg, transcranial distance increased in proportion with the ICP increase (y=12 x - 76, r=0.938), where y is changes in transcranial distance in microns and x is ICP in mmHg. In the data recorded while ICP pulsations were generated, fast Fourier transform analysis demonstrated that cranial pulsations were clearly associated with ICP pulsations. The results indicate that changes in transcranial distance is linearly correlated with those in ICP, and also that the PPLL device has sufficient sensitivity to detect transcranial pulsations which occur in association with the cardiac cycle. By analyzing the magnitude of cranial pulsations, we may be able to estimate the pressure-volume index in the cranium. As a result, estimates of intracranial compliance may be possible by using the PPLL device. Further studies are necessary in normal subjects and patients.

  11. Wind tunnel unsteady pressure measurements using a differential optical fiber Fabry-Perot pressure sensor

    Science.gov (United States)

    Correia, Ricardo; Staines, Stephen E.; James, Stephen W.; Lawson, Nicholas; Garry, Kevin; Tatam, Ralph P.

    2014-05-01

    A differential extrinsic optical fiber Fabry-Perot based pressure sensor has been developed and benchmarked against a conventional piezoresistive Kulite pressure sensor. The sensors were placed on the fuselage of a 1:10/3 sub-scale model of a Scottish aviation Bulldog, which was placed in a wind-tunnel. Pressure tappings that surrounded the sensors aided the mapping of pressure distribution around this section of the fuselage. The results obtained from the fibre optic pressure sensor are in good agreement with those obtained from the Kulite and from the pressure tappings.

  12. Anisotropic pressure molecular dynamics for atomic fluid systems

    Energy Technology Data Exchange (ETDEWEB)

    Romero-Bastida, M [Facultad de Ciencias, Universidad Autonoma del Estado de Morelos, Avenida Universidad 1001, Chamilpa, Cuernavaca, Morelos 62209 (Mexico); Lopez-Rendon, R [Departamento de QuImica, Universidad Autonoma Metropolitana-Iztapalapa, Av San Rafael Atlixco 186, 09340 Mexico DF (Mexico)

    2007-07-20

    The MTK equations (Martyna G J, Tobias D J and Klein M L 1994 J. Chem. Phys. 101 4177-89), which simulate the constant-pressure, constant-temperature NPT ensemble, have been modified to simulate an anisotropic pressure along a single coordinate axis, thus rendering the NP{sub zz}T ensemble. The necessary theory of non-Hamiltonian systems is briefly reviewed in order to analytically prove that the proposed equations indeed sample the desired ensemble. A previously derived geometric integrator for the MTK equations is modified to take into account the anisotropic pressure and volume fluctuations. We choose a Lennard-Jones fluid as an illustrative example. The density distribution function, as well as various thermodynamic and interfacial properties of the model system in a liquid-vapour coexistence state, was computed to test the robustness of the proposed equations of motion to simulate the NP{sub zz}T ensemble.

  13. Development and characterization of a multilayer matrix textile sensor for interface pressure measurements

    Science.gov (United States)

    Baldoli, Ilaria; Maselli, Martina; Cecchi, Francesca; Laschi, Cecilia

    2017-10-01

    Matrix textile sensors hold great potential for measuring pressure distribution in applications of modern daily lives, mainly regarding the biomedical field, but also robotics, automotive systems, and wearable and consumer electronics. However, an experimental analysis of their metrological properties is lacking in the literature, thus compromising their widespread acceptance. In the present work, we report the characterization of an 8 × 8 textile sensor assembled by sandwiching a piezoresistive fabric sheet between two outer fabric layers embedding conductive rows and columns. The location of the applied pressure can be identified by detecting the position where the change of resistances occurs between the external conductive paths. The sensor structure, its electrical circuit and characteristics are described in detail, after studying both the integration levels of the hierarchical structure and the composition of the piezoresistive fabric sheet. The pressure measurement range and the calibration curve were studied by tuning circuital parameters. Repeatability, time drift, temperature dependence, signal-to-noise ratio and dynamic response were analyzed. Novel tests were employed to consider the sensor sensitivity to stretch, shear force and surface curvature. A special analysis was taken over hysteresis and dynamic accuracy, focusing on a possible compensating solution. Results indicated that the system provides overall good quality performances with the main drawback of a limited dynamic accuracy, typical of piezoresistive sensing elements. Nevertheless, the use of textiles allows the realization of lightweight, wearable, washable, thin and stretchable sensors. In addition fabric sensors are robust, cheap, easy-to-use and employable to cover large area three dimensional surfaces. The wide characterization reported here could provide precious insights and guidelines to help researchers and users in taking advantages from all of these benefits, supporting them in

  14. Static and dynamic tensile behaviour of aluminium processed by high pressure torsion

    NARCIS (Netherlands)

    Verleysen, P.; Oelbrandt, W.; Naghdy, S.; Kestens, L.

    2015-01-01

    High pressure torsion (HPT) is a severe plastic deformation technique in which a small, disk-like sample is subjected to a torsional deformation under a high hydrostatic pressure. In present study, the static and dynamic tensile behaviour of commercially pure aluminium (99.6 wt%) processed by HPT is

  15. Comparison of Iterative Methods for Computing the Pressure Field in a Dynamic Network Model

    DEFF Research Database (Denmark)

    Mogensen, Kristian; Stenby, Erling Halfdan; Banerjee, Srilekha

    1999-01-01

    In dynamic network models, the pressure map (the pressure in the pores) must be evaluated at each time step. This calculation involves the solution of a large number of nonlinear algebraic systems of equations and accounts for more than 80 of the total CPU-time. Each nonlinear system requires...

  16. [Instrumentation for blood pressure measurements: historical aspects, concepts and sources of error].

    Science.gov (United States)

    de Araujo, T L; Arcuri, E A; Martins, E

    1998-04-01

    According to the International Council of Nurses the measurement of blood pressure is the procedure most performed by nurses in all the world. The aim of this study is to analyse the polemical aspects of instruments used in blood pressure measurement. Considering the analyses of the literature and the American Heart Association Recommendations, the main source of errors when measuring blood pressure are discussed.

  17. Pressure measurement in HV circuit-breaker; Mesure de pression dans un disjoncteur H.T.

    Energy Technology Data Exchange (ETDEWEB)

    Mottet, C. [Schneider Electric, Groupe appareillage, Lab. d' Essai A1, 75 - Paris (France)

    2002-06-01

    Electric arc pressure measurement in an HV circuit-breaker is fraught with difficulties concerning insulation, equi-potentiality, electromagnetic interference, corrosiveness of SF{sub 6} gas, and pressure and temperature rise. None of the many measurement methods attempted to data has proved wholly satisfactory. This article sets out an optical solution that does overcome the difficulties involved in measuring arc pressure. (author)

  18. MEASUREMENT-TO-MEASUREMENT BLOOD PRESSURE VARIABILITY IS RELATED TO COGNITIVE PERFORMANCE: THE MAINE-SYRACUSE STUDY

    Science.gov (United States)

    Crichton, Georgina E.; Elias, Merrill F.; Dore, Gregory A.; Torres, Rachael V.; Robbins, Michael A.

    2014-01-01

    The objective was to investigate the association between variability in blood pressure and cognitive function for sitting, standing and reclining blood pressure values, and variability derived from all 15 measures. In previous studies only sitting blood pressure values have been examined, and only a few cognitive measures have been employed. A secondary objective was to examine associations between blood pressure variability and cognitive performance in hypertensive individuals stratified by treatment success. Cross-sectional analyses were performed on 972 participants of the Maine Syracuse Study for whom 15 serial blood pressure clinic measures (5 sitting, 5 recumbant and 5 standing) were obtained, prior to testing of cognitive performance. Using all 15 measures, higher variability in systolic and diastolic blood pressure was associated with poorer performance on multiple measures of cognitive performance, independent of demographic factors, cardiovascular risk factors, and pulse pressure. When sitting, reclining and standing systolic blood pressure values were compared, only variability in standing blood pressure was related to measures of cognitive performance. However, for diastolic blood pressure, variability in all three positions was related to cognitive performance. Mean blood pressure values were weaker predictors of cognition. Furthermore, higher overall variability in both systolic and diastolic blood pressure was associated with poorer cognitive performance in unsuccessfully treated hypertensive individuals (with blood pressure ≥140/90 mmHg), but these associations were not evident in those with controlled hypertension. PMID:25156168

  19. Intramuscular compartment pressure measurement in chronic exertional compartment syndrome: new and improved diagnostic criteria.

    Science.gov (United States)

    Roscoe, David; Roberts, Andrew J; Hulse, David

    2015-02-01

    Patients with chronic exertional compartment syndrome (CECS) have pain during exercise that subsides with rest. Diagnosis is usually confirmed by intramuscular compartment pressure (IMCP) measurement. Controversy exists regarding the accuracy of existing diagnostic criteria. (1) To compare dynamic IMCP measurement and anthropometric factors between patients with CECS and asymptomatic controls and (2) to establish the diagnostic utility of dynamic IMCP measurement. Cohort study (diagnosis); Level of evidence, 2. A total of 40 men aged 21 to 40 years were included in the study: 20 with symptoms of CECS of the anterior compartment and 20 asymptomatic controls. Diagnoses other than CECS were excluded with rigorous inclusion criteria and magnetic resonance imaging. The IMCP was measured continuously before, during, and after participants exercised on a treadmill, wearing identical footwear and carrying a 15-kg load. Pain experienced by study subjects increased incrementally as the study progressed (P compartment IMCP is elevated immediately upon standing at rest in subjects with CECS. In patients with symptoms consistent with CECS, diagnostic utility of IMCP measurement is improved when measured continuously during exercise. A cutoff of 105 mm Hg in phase 2 provides better diagnostic accuracy than do the Pedowitz criteria of 30 mm Hg and 20 mm Hg at 1 and 5 minutes after exercise, respectively. © 2014 The Author(s).

  20. Time-averaged second-order pressure and velocity measurements in a pressurized oscillating flow prime mover

    Energy Technology Data Exchange (ETDEWEB)

    Paridaens, Richard [DynFluid, Arts et Metiers, 151 boulevard de l' Hopital, Paris (France); Kouidri, Smaine [LIMSI-CNRS, Orsay Cedex (France)

    2016-11-15

    Nonlinear phenomena in oscillating flow devices cause the appearance of a relatively minor secondary flow known as acoustic streaming, which is superimposed on the primary oscillating flow. Knowledge of control parameters, such as the time-averaged second-order velocity and pressure, would elucidate the non-linear phenomena responsible for this part of the decrease in the system's energetic efficiency. This paper focuses on the characterization of a travelling wave oscillating flow engine by measuring the time-averaged second order pressure and velocity. Laser Doppler velocimetry technique was used to measure the time-averaged second-order velocity. As streaming is a second-order phenomenon, its measurement requires specific settings especially in a pressurized device. Difficulties in obtaining the proper settings are highlighted in this study. The experiments were performed for mean pressures varying from 10 bars to 22 bars. Non-linear effect does not constantly increase with pressure.

  1. Quantitative Imaging of Turbulent Mixing Dynamics in High-Pressure Fuel Injection to Enable Predictive Simulations of Engine Combustion

    Energy Technology Data Exchange (ETDEWEB)

    Frank, Jonathan H. [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Reacting Flows Dept.; Pickett, Lyle M. [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Engine Combustion Dept.; Bisson, Scott E. [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Remote Sensing and Energetic Materials Dept.; Patterson, Brian D. [Sandia National Lab. (SNL-CA), Livermore, CA (United States). combustion Chemistry Dept.; Ruggles, Adam J. [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Reacting Flows Dept.; Skeen, Scott A. [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Engine Combustion Dept.; Manin, Julien Luc [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Engine Combustion Dept.; Huang, Erxiong [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Reacting Flows Dept.; Cicone, Dave J. [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Engine Combustion Dept.; Sphicas, Panos [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Engine Combustion Dept.

    2015-09-01

    In this LDRD project, we developed a capability for quantitative high - speed imaging measurements of high - pressure fuel injection dynamics to advance understanding of turbulent mixing in transcritical flows, ignition, and flame stabilization mechanisms, and to provide e ssential validation data for developing predictive tools for engine combustion simulations. Advanced, fuel - efficient engine technologies rely on fuel injection into a high - pressure, high - temperature environment for mixture preparation and com bustion. Howe ver, the dynamics of fuel injection are not well understood and pose significant experimental and modeling challenges. To address the need for quantitative high - speed measurements, we developed a Nd:YAG laser that provides a 5ms burst of pulses at 100 kHz o n a robust mobile platform . Using this laser, we demonstrated s patially and temporally resolved Rayleigh scattering imaging and particle image velocimetry measurements of turbulent mixing in high - pressure gas - phase flows and vaporizing sprays . Quantitativ e interpretation of high - pressure measurements was advanced by reducing and correcting interferences and imaging artifacts.

  2. Endoscopic PIV measurements in a low pressure turbine rig

    Energy Technology Data Exchange (ETDEWEB)

    Kegalj, Martin; Schiffer, Heinz-Peter [Technische Universitaet Darmstadt (Germany). Department of Gas Turbines and Aerospace Propulsion

    2009-10-15

    Particle-Image-Velocimetry (PIV) is a useful way to acquire information about the flow in turbomachinery. Several premises have to be fulfilled to achieve high-quality data, for example, optical access, low vibrations and low reflections. However, not all test facilities comply with these requirements. If there is no optical access to the test area, measurements cannot be performed. The use of borescopic optics is a possible solution to this issue, as the access required is very small. Several different techniques can be used to measure the three components of the velocity vector, one of which is Stereo-PIV. These techniques require either large optical access from several viewing angles or highly complex setups. Orthogonal light sheet orientations in combination with borescopic optics using Planar-PIV can deliver sufficient information about the flow. This study will show the feasibility of such an approach in an enclosed test area, such as the interblade space in a Low-Pressure-Turbine-Rig. The results from PIV will be compared with data collected with conventional techniques, such as the Five-Hole-Probe and the 2-component Hot-Wire-Anemometry. An analysis of time- and phase-averaged data will be performed. (orig.)

  3. Comparison of automated oscillometric versus auscultatory blood pressure measurement.

    Science.gov (United States)

    Landgraf, Johanna; Wishner, Stanley H; Kloner, Robert A

    2010-08-01

    Most clinical offices rely on automated oscillometric devices to measure blood pressure (BP), but the accuracy of this technique versus auscultatory determination using a mercury manometer is controversial. To assess the accuracy of automated oscillometric readings, BP was measured from the same site and cuff, in 337 consecutive patients seen in a routine cardiology office, using a simultaneous connection to an automated oscillometric and a mercury manometer technique. The mean systolic BP (133 +/- 20 mm Hg) and diastolic BP (72 +/- 11 mm Hg) were significantly greater using the mercury manometer than the automated oscillometric technique (systolic 131 +/- 18 and diastolic 70 +/- 12 mm Hg, p mercury manometer) in systolic BP were seen in 22% of all patients. Discrepancies in diastolic BP were seen in 20% of all patients. The mean of the discrepancy between the 2 techniques was 1.95 +/- 5 mm Hg (range 1 to 26) for systolic BP and 1.3 +/- 4 mm Hg (range 1 to 25) for diastolic BP. The discrepancies were greater in patients >65 years. In conclusion, the mercury manometer technique resulted in consistently greater BP values than oscillometric devices. These findings have important clinical implications, including the concept that patients whose BP appears to be under control using the oscillometric technique might not be at their goal BP and might have been undertreated.

  4. The dynamic scale display digital pressure gauge%动态刻度显示数字压力表

    Institute of Scientific and Technical Information of China (English)

    王浩

    2014-01-01

    The dynamic scale display digital pressure gauge provides an intuitive dynamic pressure scale display, which not only uses the same digital pressure gauge and general digital display pressure values, and can be used LED string light off analog disc mechanical pressure gauge pointer indicates the instant value of the pressure, with the LED lights steady visual analog display measuring signal set upper limit, lower limit value.%针对现有数字压力表在显示方面的不足,开发设计了一种能够同时具有两种显示方式的动态刻度显示数字压力表。它不仅能够和一般数字压力表一样采用数码管显示压力值,而且可以用LED灯串模拟圆盘式机械压力表指针指示即时压力值,用常亮LED灯直观地模拟显示设定测量信号的上限值、下限值。

  5. Thomson Scattering Measurements of Plasma Dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Holl, A; Redmer, R; Tschentscher, T; Toleikis, S; Forster, E; Cao, L; Glenzer, S H; Neumayer, P

    2006-03-29

    The authors propose to investigate the dynamics of plasmas in the warm dense matter (WDM) regime on ultra-short time scales. Accessible plasma conditions are in the density range of n = 10{sup 20} - 10{sup 23} cm{sup -3} and at moderate temperatures of T = 1 - 20 eV. These plasmas are of importance for laboratory astrophysics, high energy density science and inertial confinement fusion. They are characterized by a coupling parameter of {Lambda} {approx}> 1, where electromagnetic interactions are of the same order as the kinetic energy. The high density of the plasma makes it opaque to radiation in the visible range and, as a consequence, UV up to x-ray radiation can be used to probe such systems. Therefore a wide range in the temperature-density plane of WDM is presently unexplored and only the VUV-FEL opens for the first time the opportunity for its detailed investigation. In equilibrium, the macroscopic state of the plasma is completely characterized by its density and temperature. In pump-probe experiments however, the plasma is initially in a nonequilibrium state and relaxes towards equilibrium within the relaxation time {tau}{sub R}. For t > {tau}{sub R}, the plasma is in an equilibrium state and expands hydrodynamically on a time scale {tau}{sub H}. The proposed experiment measures the time-resolved Thomson scattering signal with the VUV-FEL radiation characterizing the plasma in equilibrium and nonequilibrium states. Both regimes are extremely interesting and will provide new insight into the following phenomena: (1) details of nonequilibrium correlations, (2) relaxation phenomena, (3) hydrodynamic expansion, (4) recombination kinetics. The time-resolved Thomson scattering signal is obtained in a pump-probe experiment by varying the delay between pump and probe. The final stage of the relaxation process (t {approx} {tau}{sub R}) is of special interest since the plasma components (electrons and ion species) can be assumed to be in quasi-equilibrium. This

  6. Evaluation on Uncertainty of Measurement Result of Pressure Transmitter Field Verification

    Institute of Scientific and Technical Information of China (English)

    CHEN; Ping

    2015-01-01

    Calibration data of pressure instrument,pressure transmitter and pressure measurement control system with field pressure calibrator on the site of production and work can represent actual situation of the production and work,reduce and avoid the error on account of the difference of

  7. Transonic Dynamics Tunnel Force and Pressure Data Acquired on the HSR Rigid Semispan Model

    Science.gov (United States)

    Schuster, David M.; Rausch, Russ D.

    1999-01-01

    This report describes the aerodynamic data acquired on the High Speed Research Rigid Semispan Model (HSR-RSM) during NASA Langley Transonic Dynamics Tunnel (TDT) Test 520 conducted from 18 March to 4 April, 1996. The purpose of this test was to assess the aerodynamic character of a rigid high speed civil transport wing. The wing was fitted with a single trailing edge control surface which was both steadily deflected and oscillated during the test to investigate the response of the aerodynamic data to steady and unsteady control motion. Angle-of-attack and control surface deflection polars at subsonic, transonic and low-supersonic Mach numbers were obtained in the tunnel?s heavy gas configuration. Unsteady pressure and steady loads data were acquired on the wing, while steady pressures were measured on the fuselage. These data were reduced using a variety of methods, programs and computer systems. The reduced data was ultimately compiled onto a CD-ROM volume which was distributed to HSR industry team members in July, 1996. This report documents the methods used to acquire and reduce the data, and provides an assessment of the quality, repeatability, and overall character of the aerodynamic data measured during this test.

  8. Pressure Measurements on a Deforming Surface in Response to an Underwater Explosion in a Water-Filled Aluminum Tube

    Directory of Open Access Journals (Sweden)

    G. Chambers

    2001-01-01

    Full Text Available Experiments have been conducted to benchmark DYSMAS computer code calculations for the dynamic interaction of water with cylindrical structures. Small explosive charges were suspended using hypodermic needle tubing inside Al tubes filled with distilled water. Pressures were measured during shock loading by tourmaline crystal, carbon resistor and ytterbium foil gages bonded to the tube using a variety of adhesives. Comparable calculated and measured pressures were obtained for the explosive charges used, with some gages surviving long enough to record results after cavitation with the tube wall.

  9. Evaluation of pancreatic tissue fluid pressure measurements intraoperatively and by sonographically guided fine-needle puncture

    DEFF Research Database (Denmark)

    Ebbehøj, N; Borly, L; Bülow, J;

    1990-01-01

    pressure measurements via direct puncture. Furthermore, no significant difference was seen between pancreatic duct and tissue fluid pressure. The technical evaluation was performed by repeated pressure measurements in human pancreatic autopsy specimens and living rats in a pressure chamber at various...... external pressure levels. The basic calibration of the method evaluated by means of this pressure chamber study showed sufficient precision and accuracy of the needle technique for clinical and investigative purposes. In conclusion, our results suggest that pancreatic tissue fluid pressure can be reliably......The aim of the present study was to evaluate the needle method for pancreatic tissue fluid pressure measurements. Clinical evaluation was performed in 24 patients with chronic pancreatitis, comparing repeated pressure measurements via sonographically guided fine-needle puncture and intraoperative...

  10. Dynamic Compression Enhances Pressure-to-Pain Threshold in Elite Athlete Recovery: Exploratory Study.

    Science.gov (United States)

    Sands, William A; McNeal, Jeni R; Murray, Steven R; Stone, Michael H

    2015-05-01

    Athlete recovery-adaptation is crucial to the progress and performance of highly trained athletes. The purpose of this study was to assess peristaltic pulse dynamic compression (PPDC) in reducing short-term pressure-to-pain threshold (PPT) among Olympic Training Center athletes after morning training. Muscular tenderness and stiffness are common symptoms of fatigue and exercise-induced muscle microtrauma and edema. Twenty-four highly trained athletes (men = 12 and women = 12) volunteered to participate in this study. The athletes were randomly assigned to experimental (n = 12) and control (n = 12) groups. Pressure-to-pain threshold measurements were conducted with a manual algometer on 3 lower extremity muscles. Experimental group athletes underwent PPDC on both legs through computer-controlled circumferential inflated leggings that used a peristaltic-like pressure pattern from feet to groin. Pressures in each cell were set to factory defaults. Treatment time was 15 minutes. The control group performed the same procedures except that the inflation pump to the leggings was off. The experimental timeline included a morning training session, followed by a PPT pretest, treatment application (PPDC or control), an immediate post-test (PPT), and a delayed post-test (PPT) after the afternoon practice session. Difference score results showed that the experimental group's PPT threshold improved after PPDC treatment immediately and persisted the remainder of the day after afternoon practice. The control group showed no statistical change. We conclude that PPDC is a promising means of accelerating and enhancing recovery after the normal aggressive training that occurs in Olympic and aspiring Olympic athletes.

  11. Dynamic Pressure of Seabed around Buried Pipelines in Shallow Water

    OpenAIRE

    Changjing Fu; Guoying Li; Tianlong Zhao; Donghai Guan

    2015-01-01

    Due to the obvious nonlinear effect caused by the shallow waves, the nonlinear wave loads have a great influence on the buried pipelines in shallow water. In order to ensure their stability, the forces on the pipelines that resulted from nonlinear waves should be considered thoroughly. Based on the Biot consolidation theory and the first-order approximate cnoidal wave theory, analytical solutions of the pore water pressure around the buried pipelines in shallow water caused by waves are first...

  12. Analysis of pressure wave dynamics in fuel rail system

    Directory of Open Access Journals (Sweden)

    B Alzahabi

    2008-09-01

    Full Text Available A model of an amplified common rail fuel system is simulated in Matlab toanalyze the wave mechanics in the rail. The injectors are modeled as asystem of linear and non-linear ODE’s consisting of masses, a helical spring,compressibility effects from fluid volumes, and hydraulic flow throughorifices. The injector simulation then predicts the rate of oil consumption,which is then input into the rail model.The rail is modeled in three sections which are coupled together. The pointswhere the coupling occurs are the locations where the current firinginjector and the pump supply are connected to the rail. This allows themodel to control the pressure and velocity (as boundary conditions atthese points. The rail model is based on the 1D, undamped wave equation,in a non-dimensional form [1] (in the position variable, x. The Reduction ofOrder method was used to solve the wave equation with the Matlabfunction PDEPE.The model was run with two different sets of initial conditions - nominal(constant pressure and zero velocity, and worst case using a simplifiedrepresentation of the pressure and velocity distribution at start of injection.This was done to determine the effect of rail waves at the start of injection,on the output of the model. The variation in fuel delivery, due to the variationin rail pressure, was then evaluated at three operating conditions - Idle,Peak Torque (PT and High Speed Light Load (HSLL. The simulation outputis then compared to analytical solutions of two forms of simplifiedgeometry, using the product method to solve the system [1.

  13. Analysis and numerical simulation of dynamic effect on rock under high pressure water jet

    Institute of Scientific and Technical Information of China (English)

    LI Xiao-hong; SI Hu; WANG Dan-dan

    2008-01-01

    Based on continuum mechanics and rock dynamics, analyzed the micro-structure damage of rock and the impulsive effect under high pressure water jet and developed the dynamic model. Further, on the assumption of that rock was homogeneous and isotropic, a computational model was established based on nonlinear finite element and Arbitrary Lagrangian-Eulerian(ALE) method. The dynamic effect impacted on rock under high pressure water jet was simulated by the dynamic contact method. The propagation of stress wave in rock was numerically simulated at different impacting velocity. The results show that the propagation velocity of stress wave is proportional to the impacting velocity of high pressure water jet. The faster the impacting velocity is, the quicker the comedown of stress wave.

  14. Measurements of turbulent pressures of flow in a water-conveying pipe containing a simulation fuel bundle

    Energy Technology Data Exchange (ETDEWEB)

    Abbasian, F.; Cao, J.; Yu, S.D. [Ryerson Univ., Dept. of Mechanical and Industrial Engineering, Toronto, Ontario (Canada)

    2008-07-01

    A test apparatus was set up to investigate the turbulent flows and flow induced vibrations in a fluid-conveying pipe containing a CANDU 43-element simulation fuel bundle. The fuel bundle is immersed in test pipe of 4-inch in diameter. A centrifugal pump circulates fresh water with a maximum velocity of 9 m/s at full pump power. The pressure fluctuation near the inner surface of the flow channel was measured at various locations using a pressure transducer and a data acquisition system. It was found that the turbulence away from the test section containing the simulation fuel bundle is largely caused by the pipe flow of high Reynolds number; the turbulence near and inside the bundle structures is the result of pipe flow and fluid-solid interactions. The measurements of pressures near the fuel bundle structure showed that the power spectral density (PSD) of pressure fluctuation has a frequency range of 1-300 Hz, and a normalized maximum pressure range of 0.04 to 0.05 times dynamic pressure. The effects of bundle angular alignments and subchannels on the pressure spectra, Strouhal number range, and streamwise pressure drop are also investigated in this paper. Results presented in this paper are useful in validating the computational models for flow-induced fluid forces that cause the fuel bundle structure to rock and fret. (author)

  15. Evaluation of pancreatic tissue fluid pressure measurements intraoperatively and by sonographically guided fine-needle puncture

    DEFF Research Database (Denmark)

    Ebbehøj, N; Borly, L; Bülow, J;

    1990-01-01

    The aim of the present study was to evaluate the needle method for pancreatic tissue fluid pressure measurements. Clinical evaluation was performed in 24 patients with chronic pancreatitis, comparing repeated pressure measurements via sonographically guided fine-needle puncture and intraoperative...... pressure measurements by direct puncture of pancreatic tissue and duct. In patients with chronic pancreatitis we found small week-to-week variations in sonographically guided percutaneous pressure measurements and good agreement between preoperative percutaneous pressure measurements and intraoperative...... external pressure levels. The basic calibration of the method evaluated by means of this pressure chamber study showed sufficient precision and accuracy of the needle technique for clinical and investigative purposes. In conclusion, our results suggest that pancreatic tissue fluid pressure can be reliably...

  16. Grip pressure measurements during activities of daily life

    Science.gov (United States)

    Sanford, Joe; Young, Carolyn; Popa, Dan; Bugnariu, Nicoleta; Patterson, Rita

    2014-06-01

    Research has expanded human-machine communication methods past direct programming and standard hand- held joystick control. Individual force sensors have been used as a simple means of providing environmental information to a robot and research has shown that more advanced sensitive skins can be viable input devices. These touch sensitive surfaces allow for additional modes of interaction between machines in open, undefined environments. These interactions include object detection for navigation and safety but can also be used for recognition of users command gestures by their machine partner. Key to successful implementation of these gestures is the understanding of varied strategies used for communication and interaction and the development of performance limits. Data of dominant hand grip forces was collected using a Tekscan Grip VersaTek Pressure Measurement System during opening of a door. Analysis of data from 10 male and female subjects is presented. The results of qualitative and quantitative analysis of these data show variability in hand configurations between users. Average data over the cohort is reported. These data will be used in future work to provide human metrology constraints and limits for use in simulation and design of new, physical human-robot interaction systems.

  17. Measurement of Threshold Pressure Gradient of Microchannels by Static Method

    Institute of Scientific and Technical Information of China (English)

    SONG Fu-Quan; JIANG Ren-Jie; BIAN Shu-Li

    2007-01-01

    The development of oil fields and laboratory experiment present the threshold pressure gradient (TPG) of liquid flow in low permeability porous media, which is called the micro-size effect in porous media. Some micro-size effects in micro-electro-mechanism systems (MEMS) are not always in agreement with each other. We propose an experiment setup to measure the TPG of microchannels by static method in the microchannels with the diameter ranging from 20-320 μm. The results present the existence of TPG in microchannel, and show an effect that the TPG of microchannel increases with decreasing hydrodynamic diameter. The relation between TPG and diameter is in agreement with single-log normalization. Additionally, the influence of errors in the experiment shows the data of experiment are valid. Finally, the mechanism of micro-size effects is discussed by revealing the facial force between liquid and solid and theory of boundary liquid, but the explanation is still not good, and needs further study.

  18. Measurement-to-measurement blood pressure variability is related to cognitive performance: the Maine Syracuse study.

    Science.gov (United States)

    Crichton, Georgina E; Elias, Merrill F; Dore, Gregory A; Torres, Rachael V; Robbins, Michael A

    2014-11-01

    The objective was to investigate the association between variability in blood pressure (BP) and cognitive function for sitting, standing, and reclining BP values and variability derived from all 15 measures. In previous studies, only sitting BP values have been examined, and only a few cognitive measures have been used. A secondary objective was to examine associations between BP variability and cognitive performance in hypertensive individuals stratified by treatment success. Cross-sectional analyses were performed on 972 participants of the Maine Syracuse Study for whom 15 serial BP clinic measures (5 sitting, 5 recumbent, and 5 standing) were obtained before testing of cognitive performance. Using all 15 measures, higher variability in systolic and diastolic BP was associated with poorer performance on multiple measures of cognitive performance, independent of demographic factors, cardiovascular risk factors, and pulse pressure. When sitting, reclining, and standing systolic BP values were compared, only variability in standing BP was related to measures of cognitive performance. However, for diastolic BP, variability in all 3 positions was related to cognitive performance. Mean BP values were weaker predictors of cognition. Furthermore, higher overall variability in both systolic and diastolic BP was associated with poorer cognitive performance in unsuccessfully treated hypertensive individuals (with BP ≥140/90 mm Hg), but these associations were not evident in those with controlled hypertension. © 2014 American Heart Association, Inc.

  19. The importance of measuring dynamic visual acuity

    National Research Council Canada - National Science Library

    Muzdalo, Natasa Vujko

    2013-01-01

    .... Beside good eyesight, drivers also have to have good reflexes and short reaction span. The aim of this study was to compare dynamic and static visual acuity in order to observe how they vary among individuals...

  20. Effects of a solar wind dynamic pressure increase in the magnetosphere and in the ionosphere

    Directory of Open Access Journals (Sweden)

    L. Juusola

    2010-10-01

    Full Text Available On 17 July 2005, an earthward bound north-south oriented magnetic cloud and its sheath were observed by the ACE, SoHO, and Wind solar wind monitors. A steplike increase of the solar wind dynamic pressure during northward interplanetary magnetic field conditions was related to the leading edge of the sheath. A timing analysis between the three spacecraft revealed that this front was not aligned with the GSE y-axis, but had a normal (−0.58,0.82,0. Hence, the first contact with the magnetosphere occurred on the dawnside rather than at the subsolar point. Fortunately, Cluster, Double Star 1, and Geotail happened to be distributed close to the magnetopause in this region, which made it possible to closely monitor the motion of the magnetopause. After the pressure front had impacted the magnetosphere, the magnetopause was perceived first to move inward and then immediately to correct the overshoot by slightly expanding again such that it ended up between the Cluster constellation with Double Star 1 inside the magnetosphere and Geotail in the magnetosheath. Coinciding with the inward and subsequent outward motion, the ground-based magnetic field at low latitudes was observed to first strengthen and then weaken. As the magnetopause position stabilised, so did the ground-based magnetic field intensity, settling at a level slightly higher than before the pressure increase. Altogether the magnetopause was moving for about 15 min after its first contact with the front. The high latitude ionospheric signature consisted of two parts: a shorter (few minutes and less intense preliminary part comprised a decrease of AL and a negative variation of PC. A longer (about ten minutes and more intense main part of the signature comprised an increase of AU and a positive variation of PC. Measurements from several ground-based magnetometer networks (210 MM CPMN, CANMOS, CARISMA, GIMA, IMAGE, MACCS, SuperMAG, THEMIS, TGO were used to obtain information on the

  1. Prehospital endotracheal intubation; need for routine cuff pressure measurement?

    NARCIS (Netherlands)

    Peters, J.H.; Hoogerwerf, N.

    2013-01-01

    In endotracheal intubation, a secured airway includes an insufflated cuff distal to the vocal cords. High cuff pressures may lead to major complications occurring after a short period of time. Cuff pressures are not routinely checked after intubation in the prehospital setting, dealing with a vulner

  2. Reliability of blood pressure measurement and cardiovascular risk prediction

    NARCIS (Netherlands)

    van der Hoeven, N.V.

    2016-01-01

    High blood pressure is one of the leading risk factors for cardiovascular disease, but difficult to reliably assess because there are many factors which can influence blood pressure including stress, exercise or illness. The first part of this thesis focuses on possible ways to improve the reliabili

  3. Atmospheric pressure changes and unexplained variability in INR measurements.

    Science.gov (United States)

    Ernst, Michael E; Shaw, Robert F; Ernst, Erika J; Alexander, Bruce; Kaboli, Peter J

    2009-06-01

    Changes in atmospheric pressure may influence hepatic blood flow and drug metabolism. Anecdotal experience suggests international normalized ratio (INR) variability may be temporally related to significant atmospheric pressure changes. We investigated this potential association in a large sample of patients with multiple INRs. This is a retrospective review of outpatient anticoagulation records from the Iowa City Veteran's Affairs Medical Center and affiliated outpatient clinics from October 1999 to July 2007. All patients, receiving at least one prescription for warfarin and INR at least 30 days or more from the date of the first warfarin prescription, were identified. INRs during periods of hospitalization and vitamin K use were excluded. Proximity analysis using geocoding of ZIP codes of identified patients to the nearest National Oceanic and Atmospheric Administration station was performed to assign atmospheric pressure with INR. Spearman's Rho and Pearson's correlation were used to evaluate atmospheric pressure and INR. Unique patients (1441) with 45 187 INRs were analyzed. When limited to nontherapeutic INRs following a previously therapeutic INR (1121 unique patients/5256 INRs), a small but clinically insignificant association between delta INR and delta atmospheric pressure was observed (r = -0.025; P = 0.038), but not for actual INR and atmospheric pressure (P = 0.06). Delta atmospheric pressure demonstrated greater variation during fall/winter months compared with spring/summer (0.23 vs. 0.15 inHg; P atmospheric pressure changes and INR variability. These findings refute the anecdotal experience seen in our anticoagulation clinic.

  4. Reliability of blood pressure measurement and cardiovascular risk prediction

    NARCIS (Netherlands)

    van der Hoeven, N.V.

    2016-01-01

    High blood pressure is one of the leading risk factors for cardiovascular disease, but difficult to reliably assess because there are many factors which can influence blood pressure including stress, exercise or illness. The first part of this thesis focuses on possible ways to improve the

  5. Central venous pulse pressure analysis using an R-synchronized pressure measurement system.

    Science.gov (United States)

    Fujita, Yoshihisa; Hayashi, Daisuke; Wada, Shinya; Yoshioka, Naoki; Yasukawa, Takeshi; Pestel, Gunther

    2006-12-01

    The information derived from central venous catheters is underused. We developed an EKG-R synchronization and averaging system to obtained distinct CVP waveforms and analyzed components of these. Twenty-five paralyzed surgical patients undergoing CVP monitoring under mechanical ventilation were studied. CVP and EKG signals were analyzed employing our system, the mean CVP and CVP at end-diastole during expiration were compared, and CVP waveform components were measured using this system. CVP waveforms were clearly visualized in all patients. They showed the a peak to be 1.8+/- 0.7 mmHg, which was the highest of three peaks, and the x trough to be lower than the y trough (-1.6+/- 0.7 mmHg and -0.9+/- 0.5 mmHg, respectively), with a mean pulse pressure of 3.4 mmHg. The difference between the mean CVP and CVP at end-diastole during expiration was 0.58+/- 0.81 mmHg. The mean CVP can be used as an index of right ventricular preload in patients under mechanical ventilation with regular sinus rhythm. Our newly developed system is useful for clinical monitoring and for education in circulatory physiology.

  6. An Elastic Tube Gage for Measuring Static and Dynamic Pressures

    Science.gov (United States)

    1948-05-01

    f^pm the free ends by means of ä spring-clip With rubberrpadded jaws*. Before the Wire is wound, the tube Is coated with cement; after the winding...Compounds such as beeswax or ceresin wax were first employed for waterproofing, but their brittleness at low temperatures was found to be ob- jectionable...Engineering Company,- New Castle, Delaware, is given in the following: 1. Apply one coat of primer, with a brush or ä spray gun, and allow It to dry one-half

  7. A comparison of blood pressure measurements in newborns.

    LENUS (Irish Health Repository)

    O'Shea, Joyce

    2012-02-01

    Blood pressure monitoring is an essential component of neonatal intensive care. We compared invasive and noninvasive (Dinamap, Marquette, and Dash) recordings in newborns and also noninvasive values obtained from upper and lower limbs. Infants\\' blood pressure was recorded every 6 hours for 72 hours using three noninvasive devices and compared with invasive readings taken simultaneously. Twenty-five babies were enrolled in the study, with birth weights of 560 to 4500 g and gestation 24 + 1 to 40 + 5 weeks. Three hundred thirty-two recordings were obtained. Comparison between invasive and noninvasive readings revealed that all three noninvasive monitors overread mean blood pressure. There was no significant difference between the cuff recordings obtained from the upper or lower limbs. All three noninvasive devices overestimated mean blood pressure values compared with invasive monitoring. Clinicians may be falsely reassured by noninvasive monitoring. Mean blood pressure values obtained from the upper and lower limb are similar.

  8. Challenges in blood pressure measurement in patients treated with maintenance hemodialysis.

    Science.gov (United States)

    Roberts, Matthew A; Pilmore, Helen L; Tonkin, Andrew M; Garg, Amit X; Pascoe, Elaine M; Badve, Sunil V; Cass, Alan; Ierino, Francesco L; Hawley, Carmel M

    2012-09-01

    The association between blood pressure and cardiovascular outcomes in patients undergoing hemodialysis remains controversial. This may relate in part to the technique and device used and the timing of the blood pressure measurement in relation to the hemodialysis procedure. Emerging evidence indicates that standardized hemodialysis unit blood pressure measurements or measurements obtained at home, either by the patient or using an ambulatory blood pressure monitor, may offer advantages over routine hemodialysis unit blood pressure measurements for determining cardiovascular risk and treatment. This review discusses the available evidence and implications for clinicians and clinical trials.

  9. Direct field measurement of the dynamic amplification in a bridge

    Science.gov (United States)

    Carey, Ciarán; OBrien, Eugene J.; Malekjafarian, Abdollah; Lydon, Myra; Taylor, Su

    2017-02-01

    In this paper, the level of dynamics, as described by the Assessment Dynamic Ratio (ADR), is measured directly through a field test on a bridge in the United Kingdom. The bridge was instrumented using fiber optic strain sensors and piezo-polymer weigh-in-motion sensors were installed in the pavement on the approach road. Field measurements of static and static-plus-dynamic strains were taken over 45 days. The results show that, while dynamic amplification is large for many loading events, these tend not to be the critical events. ADR, the allowance that should be made for dynamics in an assessment of safety, is small.

  10. Level of Mercury Manometer With Respect to Heart: Does it Affect Blood Pressure Measurement?

    Science.gov (United States)

    Kapoor, Raj; Roy, V K; Manna, S; Bhattacharjee, M

    2015-01-01

    Measurement of blood pressure is an integral part of clinical examination. Over the years various types of instruments have been used to measure blood pressure but till date the mercury sphygmomanometer is regarded as the gold standard. However, there is a myth prevalent among health professionals regarding the level of the manometer in relation to heart at the time of measuring of blood pressure. Many professionals insist that it has to be placed at the level of the heart. We argue that the limb from which pressure is measured must be at the heart level rather than the manometer. We conducted a study in which we measured the blood pressure in adults by placing the manometer at three different levels with respect to the heart. The values of blood pressure obtained at all levels were similar and did not show any statistically significant difference. We therefore conclude that the level of sphygmomanometer per se does not affect blood pressure measurement.

  11. Quasi-elastic neutron scattering study on water and polymer dynamics in thermo/pressure sensitive polymer solutions.

    Science.gov (United States)

    Osaka, Noboru; Shibayama, Mitsuhiro; Kikuchi, Tatsuya; Yamamuro, Osamu

    2009-10-01

    Dynamics of water and poly(N-isopropylacrylamide) (PNIPA) in concentrated aqueous solutions, where the majority of water molecules are attached to polymer chains, has been investigated with use of incoherent quasi-elastic neutron scattering (QENS) and dynamic light scattering (DLS) measurements as functions of temperature, T, and hydrostatic pressure, P. It was observed by QENS that the self-diffusion coefficient, D(water), of water in PNIPA/H(2)O solutions increased by P at temperatures below the lower critical solution temperature (LCST) of PNIPA aqueous solutions. However, above the LCST, D(water) decreased by P, as is often reported in non-hydrogen bonding solutions. In isobaric heating runs, therefore, the jump in D(water) at LCST decreased with increasing pressure. On the other hand, the mean-square displacement, , of the local vibrational motion of PNIPA in PNIPA/D(2)O solutions, where the incoherent scattering signal of PNIPA was predominantly observed, was reduced due to the aggregation behavior of PNIPA by pressurizing, which was also confirmed by using DLS. The jump in at the LCST became gradual by pressurizing, which was consistent with the changes of the dynamics of water obtained in PNIPA/H(2)O solutions.

  12. Dynamic response of vaporizing droplet to pressure oscillation

    Science.gov (United States)

    Yuan, Lei; Shen, Chibing; Zhang, Xinqiao

    2017-02-01

    Combustion instability is a major challenge in the development of the liquid propellant engines, and droplet vaporization is viewed as a potential mechanism for driving instabilities. Based on the previous work, an unsteady droplet heating and vaporization model was developed. The model and numerical method are validated by experimental data available in literature, and then the oscillatory vaporization of n-Heptane droplet exposed to unsteady harmonic nitrogen atmosphere was numerically investigated over a wide range of amplitudes and frequencies. Also, temperature variations inside the droplet were demonstrated under oscillation environments. It was found that the thermal wave is attenuated with significantly reduced wave intensities as it penetrates deep into droplet from the ambient gas. Droplet surface temperature exhibits smaller fluctuation than that of the ambient gas, and it exhibits a time lag with regard to the pressure variation. Furthermore, the mechanism leading to phase lag of vaporization rate with respect to pressure oscillation was unraveled. Results show that this phase lag varies during the droplet lifetime and it is strongly influenced by oscillation frequency, indicating droplet vaporization is only capable of driving combustion instability in some certain frequency domains. Instead, the amplitude of the oscillation does not have very significant effects. It is noteworthy that thermal inertia of the droplet also plays a considerable role in determining the phase lag.

  13. Performance evaluation of Honeywell silicon piezoresistive pressure transducers for oceanographic and limnological measurements

    Digital Repository Service at National Institute of Oceanography (India)

    VijayKumar, K.; Joseph, A.; Desai, R.G.P.; Prabhudesai, S.; Nagvekar, S.; Damodaran, V.

    and limnological measurements, have been carried out at four differing temperatures (10 degrees, 20 degrees, 30 degrees, and 40 degrees C) to evaluate their suitability for such applications. The full-scale pressure range of these shallow water absolute pressure...

  14. The Correlation between Systolic Blood Pressure Measured by Return to Flow Versus Systolic Blood Pressure Measured by Arterial Catheter in the Adult Anesthetized Patient.

    Science.gov (United States)

    1986-12-01

    a U-tube and mercury manometer for other research, he did not use it to measure arterial blood pressure (30). It was almost a century 34 N N 35 later...use of this mercury manometer decreased the size of the measuring apparatus more than 27 times (30). Carl Ludwig made an important contribution to...direct measurement of blood pressure in 1847 when he added a i graphic recording device to the mercury manometer . This eliminated observer error and

  15. Thirty-minute compared to standardised office blood pressure measurement in general practice.

    NARCIS (Netherlands)

    Scherpbier-de Haan, N.D.; Wel, M. van der; Schoenmakers, G.; Boudewijns, S.; Peer, P.G.M.; Weel, C. van; Thien, Th.; Bakx, J.C.

    2011-01-01

    Background Although blood pressure measurement is one of the most frequently performed measurements in clinical practice, there are concerns about its reliability. Serial, automated oscillometric blood pressure measurement has the potential to reduce measurement bias and white-coat effect' Aim To

  16. Evaluation of Dynamic Soil-Structure Interaction and Dynamic Seismic Soil Pressures Acting on It Subjected to Strong Earthquake Motions

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In order to clarify the damage mechanism of the subway structure, the dynamic soil-structure interaction and the dynamic forces acting on the structure, a series of shaking table tests and simulation analyses were performed. The seismic response of the structure and the dynamic forces acting on the structure due to sinusoidal and random waves were investigated with special attention to the dynamic soil-structure interaction. The result shows that the compression seismic soil pressures and extension seismic soil pressures simultaneously act on the sidewalls, and big shear stress also acts on the ceiling slab due to horizontal excitation. The seismic soil pressure could be approximated to hyperbola curve, and reached a peak value with increase of the shear strain of the model ground. In addition, a slide and exfoliation phenomenon between the structure and the surrounding ground was simulated, using the nonlinear analyses. The foundation is provided for amending the calculation method of seismic soil pressure and improving the anti-earthquake designing level of underground structure.

  17. Peripheral arterial volume distensibility: significant differences with age and blood pressure measured using an applied external pressure.

    Science.gov (United States)

    Zheng, Dingchang; Murray, Alan

    2011-05-01

    A new arterial distensibility measurement technique was assessed in 100 healthy normotensive subjects. Arterial transmural pressures on the whole right arm were reduced with a 50 cm long cuff inflated to 10, 20, 30 and 40 mmHg. The electrocardiogram, and finger and ear photoplethysmograms were recorded simultaneously. Arm pulse propagation time, pulse wave velocity (PWV) and arterial volume distensibility were determined. With a 40 mmHg reduction in transmural pressure, arm pulse propagation time increased from 61 to 83 ms, PWV decreased from 12 to 8 m s(-1) and arterial distensibility increased from 0.102% to 0.232% per mmHg (all P pressures, arterial distensibility was significantly related to resting mean arterial pressure (MAP), diastolic blood pressure (DBP) and age, and for systolic blood pressure at 30 and 40 mmHg (all P pressure, arterial distensibility fell by 54% for a MAP increase from 75 to 105 mmHg, 57% for a DBP increase from 60 to 90 mmHg and 47% for an age increase from 20 to 70 years. These changes were more than double than those without cuff pressure. Our technique showed that systemic volume distensibility of the peripheral arm artery reduced with age, with a greater effect at higher external and lower transmural pressures.

  18. COMPUTATIONAL FLUID DYNAMICS RESEARCH ON PRESSURE LOSS OF CROSS-FLOW PERFORATED MUFFLER

    Institute of Scientific and Technical Information of China (English)

    HU Xiaodong; ZHOU Yiqi; FANG Jianhua; MAN Xiliang; ZHAO Zhengxu

    2007-01-01

    The pressure loss of cross-flow perforated muffler has been computed with the procedure of physical modeling, simulation and data processing. Three-dimensional computational fluid dynamics (CFD) has been used to investigate the relations of porosities, flow velocity and diameter of the holes with the pressure loss. Accordingly, some preliminary results have been obtained that pressure loss increases with porosity descent as nearly a hyperbolic trend, rising flow velocity of the input makes the pressure loss increasing with parabola trend, diameter of holes affects little about pressure loss of the muffler. Otherwise, the holes on the perforated pipes make the air flow gently and meanly,which decreases the air impact to the wall and pipes in the muffler. A practical perforated muffler is used to illustrate the available of this method for pressure loss computation, and the comparison shows that the computation results with the method of CFD has reference value for muffler design.

  19. Indication for shunt operation of normal pressure hydrocephalus. Combined assessment of infusion test and dynamic CT scan

    Energy Technology Data Exchange (ETDEWEB)

    Jinnai, Takahiro; Nagao, Seigo [Kagawa Medical Univ., Miki (Japan); Kuyama, Hideyuki

    2000-03-01

    Normal pressure hydrocephalus (NPH) is one of the diseases that causes a neuro-surgically treatable form of dementia. Although patients with NPH can be treated with shunt operation, reliable indications for the surgery are not yet established. In this study, 20 NPH patients diagnosed by clinical symptoms were subjected to combined assessment by infusion test and dynamic CT scan, a useful diagnostic tool to select a shunt responsive cases. Patients were evaluated by measuring sequential changes in the density of the periventricular lucency (PVL) using dynamic CT scan and continuous lumbar subdural pressure monitoring during an infusion manometric test at a rate of 0.8 ml/min for 30 min. The average lumbar subdural pressure during infusion manometric test in the shunt responsive group was 18.4{+-}5.8 mmHg, which was significantly higher than that in the shunt non-responsive group which was 10.0{+-}4.0 mmHg (p<0.01). The relative changes in PVL density in the dynamic CT was also significantly higher in the shunt responsive group (0.99{+-}0.61 HU) compared to the shunt non-responsive group (0.15{+-}0.32) (p<0.01). Dynamic CT scan with infusion manometric test is useful in the selection of patients with NPH who are likely to respond to shunt surgery. (author)

  20. Method for Standardizing Sonic-Boom Model Pressure Signatures Measured at Several Wind-Tunnel Facilities

    Science.gov (United States)

    Mack, Robert J.

    2007-01-01

    Low-boom model pressure signatures are often measured at two or more wind-tunnel facilities. Preliminary measurements are made at small separation distances in a wind tunnel close at hand, and a second set of pressure signatures is measured at larger separation distances in a wind-tunnel facility with a larger test section. In this report, a method for correcting and standardizing the wind-tunnel-measured pressure signatures obtained in different wind tunnel facilities is presented and discussed.

  1. High speed high dynamic range high accuracy measurement system

    Energy Technology Data Exchange (ETDEWEB)

    Deibele, Craig E.; Curry, Douglas E.; Dickson, Richard W.; Xie, Zaipeng

    2016-11-29

    A measuring system includes an input that emulates a bandpass filter with no signal reflections. A directional coupler connected to the input passes the filtered input to electrically isolated measuring circuits. Each of the measuring circuits includes an amplifier that amplifies the signal through logarithmic functions. The output of the measuring system is an accurate high dynamic range measurement.

  2. Measurement of Dynamic Resistance in Resistance Spot Welding

    DEFF Research Database (Denmark)

    Wu, Pei; Zhang, Wenqi; Bay, Niels

    Through years, the dynamic resistance across the electrodes has been used for weld quality estimation and contact resistance measurement. However, the previous methods of determining the dynamic resistance were mostly based on measuring the voltage and current on the secondary side...... of the transformer in resistance welding machines, implying defects from induction noise and interference with the leads connected to the electrodes for measuring the voltage. In this study, the dynamic resistance is determined by measuring the voltage on the primary side and the current on the secondary side......, as another application, the proposed method is used to measure the faying surface contact resistance....

  3. Measurement of Dynamic Resistance in Resistance Spot Welding

    DEFF Research Database (Denmark)

    Wu, Pei; Zhang, Wenqi; Bay, Niels

    Through years, the dynamic resistance across the electrodes has been used for weld quality estimation and contact resistance measurement. However, the previous methods of determining the dynamic resistance were mostly based on measuring the voltage and current on the secondary side...... of the transformer in resistance welding machines, implying defects from induction noise and interference with the leads connected to the electrodes for measuring the voltage. In this study, the dynamic resistance is determined by measuring the voltage on the primary side and the current on the secondary side......, as another application, the proposed method is used to measure the faying surface contact resistance....

  4. Turgor pressure: direct manometric measurement in single cells of Nitella.

    Science.gov (United States)

    Green, P B; Stanton, F W

    1967-03-31

    A small capillary, fused at one end, serves as a micromanometer when the open end is inserted into a large Nitella cell. The cell's ability to compress the gas reveals its turgor pressure directly-save for a small correction due to capillarity. The method gives a lower limit to turgor pressure for the same cell in the normal state. The common method, incipient plasmolysis, gives an upper limit. On Nitella axillaris cells the two methods limit the turgor pressure at 5.1 to 5.7 atmospheres. The manometric method is also applicable to growing cells, where osmotic equilibrium is not present.

  5. Role of Repeat Muscle Compartment Pressure Measurements in Chronic Exertional Compartment Syndrome of the Lower Leg

    Science.gov (United States)

    van Zantvoort, Aniek P. M.; de Bruijn, Johan A.; Winkes, Michiel B.; Hoogeveen, Adwin R.; Teijink, Joep A. W.; Scheltinga, Marc R.

    2017-01-01

    Background: The diagnostic gold standard for diagnosing chronic exertional compartment syndrome (CECS) is a dynamic intracompartmental pressure (ICP) measurement of the muscle. The potential role of a repeat ICP (re-ICP) measurement in patients with persistent lower leg symptoms after surgical decompression or with ongoing symptoms after an earlier normal ICP is unknown. Purpose: To study whether re-ICP measurements in patients with persistent CECS-like symptoms of the lower leg may contribute to the diagnosis of CECS after both surgical decompression and a previously normal ICP measurement. Study Design: Case series; Level of evidence, 4. Methods: Charts of patients who underwent re-ICP measurement of lower leg compartments (anterior [ant], deep posterior [dp], and/or lateral [lat] compartments) between 2001 and 2013 were retrospectively studied. CECS was diagnosed on the basis of generally accepted cutoff pressures for newly onset CECS (Pedowitz criteria: ICP at rest ≥15 mmHg, ≥30 mmHg after 1 minute, or ≥20 mmHg 5 minutes after a provocative test). Factors predicting recurrent CECS after surgery or after a previously normal ICP measurement were analyzed. Results: A total of 1714 ICP measurements were taken in 1513 patients with suspected CECS over a 13-year observation period. In all, 201 (12%) tests were re-ICP measurements for persistent lower leg symptoms. Based on the proposed ICP cutoff values, CECS recurrence was diagnosed in 16 of 62 previously operated compartments (recurrence rate, 26%; 53 patients [64% female]; median age, 24 years; age range, 15-78 years). Recurrence rates were not different among the 3 lower leg CECS compartments (ant-CECS, 17%; dp-CECS, 33%; lat-CECS, 30%; χ2 = 1.928, P = .381). Sex (χ2 = 0.058, P = .810), age (U = 378, z = 1.840, P = .066), bilaterality (χ2 = 0.019, P = .889), and prefasciotomy ICP did not predict recurrence. Re-ICP measurements evaluating 20 compartments with previously normal ICP measurements (15

  6. Role of Repeat Muscle Compartment Pressure Measurements in Chronic Exertional Compartment Syndrome of the Lower Leg.

    Science.gov (United States)

    van Zantvoort, Aniek P M; de Bruijn, Johan A; Winkes, Michiel B; Hoogeveen, Adwin R; Teijink, Joep A W; Scheltinga, Marc R

    2017-06-01

    The diagnostic gold standard for diagnosing chronic exertional compartment syndrome (CECS) is a dynamic intracompartmental pressure (ICP) measurement of the muscle. The potential role of a repeat ICP (re-ICP) measurement in patients with persistent lower leg symptoms after surgical decompression or with ongoing symptoms after an earlier normal ICP is unknown. To study whether re-ICP measurements in patients with persistent CECS-like symptoms of the lower leg may contribute to the diagnosis of CECS after both surgical decompression and a previously normal ICP measurement. Case series; Level of evidence, 4. Charts of patients who underwent re-ICP measurement of lower leg compartments (anterior [ant], deep posterior [dp], and/or lateral [lat] compartments) between 2001 and 2013 were retrospectively studied. CECS was diagnosed on the basis of generally accepted cutoff pressures for newly onset CECS (Pedowitz criteria: ICP at rest ≥15 mmHg, ≥30 mmHg after 1 minute, or ≥20 mmHg 5 minutes after a provocative test). Factors predicting recurrent CECS after surgery or after a previously normal ICP measurement were analyzed. A total of 1714 ICP measurements were taken in 1513 patients with suspected CECS over a 13-year observation period. In all, 201 (12%) tests were re-ICP measurements for persistent lower leg symptoms. Based on the proposed ICP cutoff values, CECS recurrence was diagnosed in 16 of 62 previously operated compartments (recurrence rate, 26%; 53 patients [64% female]; median age, 24 years; age range, 15-78 years). Recurrence rates were not different among the 3 lower leg CECS compartments (ant-CECS, 17%; dp-CECS, 33%; lat-CECS, 30%; χ(2) = 1.928, P = .381). Sex (χ(2) = 0.058, P = .810), age (U = 378, z = 1.840, P = .066), bilaterality (χ(2) = 0.019, P = .889), and prefasciotomy ICP did not predict recurrence. Re-ICP measurements evaluating 20 compartments with previously normal ICP measurements (15 patients [53% female]; mean age, 31 ± 10 years

  7. High-speed visualization and radiated pressure measurement of a laser-induced gas bubble in glycerin-water solutions

    Science.gov (United States)

    Nakajima, Takehiro; Kondo, Tomoki; Ando, Keita

    2016-11-01

    We study the dynamics of a spherical gaseous bubble created by focusing a nanosecond laser pulse at 532 nm into a large volume of glycerin-water solutions. Free oscillation of the bubble and shock wave emission from the bubble dynamics are recorded by a high-speed camera together with a pulse laser stroboscope; concurrently, pressure radiated from the oscillating bubble is measured by a hydrophone. The bubble achieves a mechanical equilibrium after free oscillation is damped out; the equilibrium state stays for a while, unlike vapor bubbles. We speculate that the bubble content is mainly gases originally dissolved in the liquid (i.e., air). The bubble dynamics we observed are compared to Rayleigh-Plesset-type calculations that account for diffusive effects; the (unknown) initial pressure just after laser focusing is tuned to obtain agreement between the experiment and the calculation. Moreover, viscous effects on the shock propagation are examined with the aid of compressible Navier-Stokes simulation.

  8. Blood pressure measurement in hemodialysis: The importance of the measurement technique.

    Science.gov (United States)

    Kubrusly, M; de Oliveira, Claudia Maria Costa; Silva, R P; Pinheiro, M A; Rocha, M B C; Magalhães, R M

    2016-03-01

    Systemic arterial hypertension contributes to the high cardiovascular morbidity in hemodialysis (HD) patients, but the accuracy of blood pressure (BP) measurement in this population has not been well studied. To evaluate the agreement between BP measurement using the routine measurement technique (usual method) and the technique recommended by the VII Joint (standard method). This cross-sectional study enrolled 124 patients in a single center who had undergone dialysis for more than three months and were 18 years of age or older. The BP was verified at the start of dialysis by the nursing team (usual method) and by the researchers (standard method). The agreement between the systolic and diastolic BP (SBP and DBP) measurements was tested by the Bland-Altman analysis. A difference in BP measurement higher than ±5 mm Hg was considered clinically significant. The studied group had a mean age of 53.2 years. The average difference between routine and standard BP measurement was -6 mm Hg for SBP (limits of agreement: -40.1-28 mm Hg; P measured by both methods was observed in 69.4% of the patients for SBP and in 61.3% for DBP. The disagreement between the results of different BP measurement methods in HD patients was significant and the BP was underestimated using the usual BP method. BP measurement standardization should be encouraged to avoid errors in diagnosis and therapy.

  9. Local Dynamical Instabilities in Magnetized, Radiation Pressure Supported Accretion Disks

    CERN Document Server

    Blaes, Omer M; Blaes, Omer; Socrates, Aristotle

    2000-01-01

    We present a general linear dispersion relation which describes the coupled behavior of magnetorotational, photon bubble, and convective instabilities in weakly magnetized, differentially rotating accretion disks. We presume the accretion disks to be geometrically thin and supported vertically by radiation pressure. We fully incorporate the effects of a nonzero radiative diffusion length on the linear modes. In an equilibrium with purely vertical magnetic field, the vertical magnetorotational modes are completely unaffected by compressibility, stratification, and radiative diffusion. However, in the presence of azimuthal fields, which are expected in differentially rotating flows, the growth rate of all magnetorotational modes can be reduced substantially below the orbital frequency. This occurs if diffusion destroys radiation sound waves on the length scale of the instability, and the magnetic energy density of the azimuthal component exceeds the non-radiative thermal energy density. While sluggish in this c...

  10. Conversion of urodynamic pressures measured simultaneously by air-charged and water-filled catheter systems.

    Science.gov (United States)

    Awada, Hassan K; Fletter, Paul C; Zaszczurynski, Paul J; Cooper, Mitchell A; Damaser, Margot S

    2015-08-01

    The objective of this study was to compare the simultaneous responses of water-filled (WFC) and air-charged (ACC) catheters during simulated urodynamic pressures and develop an algorithm to convert peak pressures measured using an ACC to those measured by a WFC. Examples of cough leak point pressure and valsalva leak point pressure data (n = 4) were obtained from the literature, digitized, and modified in amplitude and duration to create a set of simulated data that ranged in amplitude from 15 to 220 cm H2 O (n = 25) and duration from 0.1 to 3.0 sec (n = 25) for each original signal. Simulated pressure signals were recorded simultaneously by WFCs, ACCs, and a reference transducer in a specially designed pressure chamber. Peak pressure and time to peak pressure were calculated for each simulated pressure signal and were used to develop an algorithm to convert peak pressures recorded with ACCs to corresponding peak pressures recorded with WFCs. The algorithm was validated with additional simulated urodynamic pressure signals and additional catheters that had not been utilized to develop the algorithm. ACCs significantly underestimated peak pressures of more rapidly changing pressures, as in coughs, compared to those measured by WFCs. The algorithm corrected 90% of peak pressures measured by ACCs to within 5% of those measured by WFCs when simultaneously exposed to the same pressure signals. The developed algorithm can be used to convert rapidly changing urodynamic pressures, such as cough leak point pressure, obtained using ACC systems to corresponding values expected from WFC systems. © 2014 Wiley Periodicals, Inc.

  11. Adaptation of a High-Pressure Liquid Chromatography System for the Measurement of Viscosity

    Directory of Open Access Journals (Sweden)

    Sonia Gregory

    2014-03-01

    Full Text Available The state-of-the-art instruments for the determination of viscosity of liquids typically require a significant amount of sample, and have relatively low throughput due to manual and sequential measurements. In this study, it was demonstrated that the pressure generated by the flow of viscous fluids through a capillary could be precisely measured employing high-pressure liquid chromatography systems (HPLC using glycerol solutions of moderate viscosity as a mobile phase, and correlated to the dynamic (absolute viscosity. The parameters allowing calculation of the viscosity of glycerol calibration standards as a function of temperature were established. The measurements were made with volumes as small as 10 μL, and the use of an autosampler permitted unattended analysis of a large number samples. The method appears to be particularly well suited for the development of viscous formulations of therapeutic, protein-based macromolecules, where the amount sample is typically limited and relatively wide ranges of conditions are considered in the optimization process. The utility of the methods was illustrated by application to the development of concentrated inactivated virus vaccines.

  12. Measurement fidelity in the presence of coherent dynamics or dissipation

    Science.gov (United States)

    You, Jian-Qiang; Ashhab, S.; Nori, Franco

    2011-03-01

    We analyze the problem of a charge qubit probed by a quantum point contact when the measurement is concurrent with Hamiltonian-induced coherent dynamics or dissipation. This additional dynamics changes the state of the qubit before the measurement is completed. As a result, the measurement fidelity is reduced. We calculate the reduction in measurement fidelity in these cases. References: S. Ashhab, J. Q. You, and F. Nori, New J. Phys. 11, 083017 (2009); Phys. Scr. T137, 014005 (2009).

  13. new method to evaluate relative efficiency measure in dynamic DEA

    OpenAIRE

    Maryam Reshadi

    2014-01-01

    As known in data envelopment analysis literature, TDT measure has been used to get the relative efficiency measure of decision making units. Then, the aim of this paper is to extend TDT measure into the dynamic framework of data envelopment analysis to get the dynamic relative efficiency measure by which units' productivity would be evaluated exactly on an assessment window. To do this, it is needed firstly to identify some factors named link factors bearing truly and exactly connectivity bet...

  14. Dielectric α-relaxation and ionic conductivity in propylene glycol and its oligomers measured at elevated pressure

    Science.gov (United States)

    Casalini, Riccardo; Roland, C. Michael

    2003-12-01

    Structural dynamics and volume were measured as a function of both temperature and pressure for a propylene glycol and its oligomers (PPG), and the results compared with previous data on higher molecular weight polypropylene glycols. PPG is of special interest because the terminal groups form hydrogen bonds; thus, by studying different molecular weights, the manner in which hydrogen bonding influences the dynamics in the supercooled regime can be systematically investigated. The fragility (Tg-normalized temperature dependence) of the dimer and trimer of PPG increases with pressure, similar to results for other H-bonded liquids, but different from van der Waals glass formers. This behavior is believed to be due to the effect of pressure in decreasing the extent of hydrogen bonding. From the combined temperature and volume dependences of the relaxation times, the relative degree to which thermal energy and volume govern the dynamics was quantified. With decreasing molecular weight, the relative contribution of thermal energy to the dynamics was found to strongly increase, reflecting the role of hydrogen bonding. By comparing the ionic conductivity and the dielectric relaxation times, a decoupling between rotational and translational motions was observed. Interestingly, this decoupling was independent of both pressure and molecular weight, indicating that hydrogen bonds have a negligible effect on the phenomenon.

  15. Unsteady pressure-sensitive paint measurement based on the heterodyne method using low frame rate camera.

    Science.gov (United States)

    Matsuda, Yu; Yorita, Daisuke; Egami, Yasuhiro; Kameya, Tomohiro; Kakihara, Noriaki; Yamaguchi, Hiroki; Asai, Keisuke; Niimi, Tomohide

    2013-10-01

    The pressure-sensitive paint technique based on the heterodyne method was proposed for the precise pressure measurement of unsteady flow fields. This measurement is realized by detecting the beat signal that results from interference between a modulating illumination light source and a pressure fluctuation. The beat signal is captured by a camera with a considerably lower frame rate than the frequency of the pressure fluctuation. By carefully adjusting the frequency of the light and the camera frame rate, the signal at the frequency of interest is detected, while the noise signals at other frequencies are eliminated. To demonstrate the proposed method, we measured the pressure fluctuations in a resonance tube at the fundamental, second, and third harmonics. The pressure fluctuation distributions were successfully obtained and were consistent with measurements from a pressure transducer. The proposed method is a useful technique for measuring unsteady phenomena.

  16. A new technique for measurements of the urethra pressure profile.

    Science.gov (United States)

    Asmussen, M; Ulmsten, U

    1976-01-01

    A new standardized technique for continuous recording of the urethral pressure profile simultaneously with intravesical pressure has been developed. The pressures were recorded using two micr-transducers enclosed in a thin Dacron catheter. The catheter moved with a constant speed through the urethra with the aid of a specially designed instrument. This instrument is described. Twenty-five healthy women were examined. The patients were divided into two groups: (A) 10 postmenopausal women, and (B) 15 fertile women. The results of the recordings showed that the functional length and the absolute length of the urethra could be reproduced with an error of less than 1 mm. The maximal pressure amplitude was significantly less in group A.

  17. An analog device to facilitate occlusion pressure measurements.

    Science.gov (United States)

    Delavault, E; Saumon, G

    1980-06-01

    The "oclusion pressure" technique is widely used to test the response of respiratory centers to CO2. The graphic treatment of the test necessitates a fast recording of the mouth pressure signal, thus using a great deal of paper and requiring a tedious interpretation. The device described here controls an electromagnetic valve closing it during expiration and opening it after a given time delay, following the onset of inspiration. During that time only, the mouth pressure signal goes through an analog switch, the highest signal value is then equal to the occlusion pressure. This device allows the use of a slow recorder without loss of information. In addition, it has the advantage of generating very short respiratory occlusions, thus sparing the subject being tested from interferences in subsequent respiratory cycles. It can be used as a pretreatment unit to be associated with a microprocessor.

  18. Fluid front displacement dynamics affecting pressure fluctuations and phase entrapment in porous media

    Science.gov (United States)

    Moebius, F.; Or, D.

    2012-04-01

    Many natural and engineering processes involve motion of fluid fronts in porous media, from infiltration and drainage in hydrology to reservoir management in petroleum engineering. Macroscopically smooth and continuous motion of displacement fronts involves numerous rapid interfacial jumps and local reconfigurations. Detailed observations of displacement processes in micromodels illustrate the wide array of fluid interfacial dynamics ranging from irregular jumping-pinning motions to gradual pore scale invasions. The pressure fluctuations associated with interfacial motions reflect not only pore geometry (as traditionally hypothesized) but there is a strong influence of boundary conditions (e.g., mean drainage rate). The time scales associated with waiting time distribution of individual invasion events and decay time of inertial oscillations (following a rapid interfacial jump) provide a means for distinguishing between displacement regimes. Direct observations using high-speed camera combined with concurrent pressure signal measurements were instrumental in clarifying influences of flow rates, pore size, and gravity on burst size distribution and waiting times. We compared our results with the early experimental and theoretical study on burst size and waiting time distribution during slow drainage processes of Måløy et al. [Måløy et al., 1992]. Results provide insights on critical invasion events that exert strong influence on macroscopic phenomena such as front morphology and residual phase entrapment behind leading to hysteresis. Måløy, K. J., L. Furuberg, J. Feder, and T. Jossang (1992), Dynamics of Slow Drainage in Porous-Media, Phys Rev Lett, 68(14), 2161-2164.

  19. Line Emission from Radiation-Pressurized HII Region II: Dynamics and Population Synthesis

    CERN Document Server

    Verdolini, Silvia; Krumholz, Mark R; Matzner, Christopher D; Tielens, Alexander G G M

    2013-01-01

    Optical and infrared emission lines from HII regions are an important diagnostic used to study galaxies, but interpretation of these lines requires significant modeling of both the internal structure and dynamical evolution of the emitting regions. Most of the models in common use today assume that HII region dynamics are dominated by the expansion of stellar wind bubbles, and have neglected the contribution of radiation pressure to the dynamics, and in some cases also to the internal structure. However, recent observations of nearby galaxies suggest that neither assumption is justified, motivating us to revisit the question of how HII region line emission depends on the physics of winds and radiation pressure. In a companion paper we construct models of single HII regions including and excluding radiation pressure and winds, and in this paper we describe a population synthesis code that uses these models to simulate galactic collections of HII regions with varying physical parameters. We show that the choice...

  20. Dynamic pressure model derived from an observation by Sakigake for Comet Halley on 31 December, 1985

    Science.gov (United States)

    Saito, Takao; Yumoto, Kiyohumi; Hirao, Kunio; Saito, Keiji; Nakagawa, Tomoko; Smith, Edward

    1986-01-01

    An outstanding disconnection event (DE)-like knot was observed on 31 Dec. 1985 in P/Halley's tail. Analysis of the Sakigake/IMF data reveals that comet Halley did not encounter the heliospheric neutral sheet on the day, demanding a new explanation of the DE-like event. During this event, the comet encountered a high-speed solar wind from a coronal hole tongue of the Sun. The event can be explained by a dynamic pressure model, according to which the DE-like plasmoid was caused by a sudden increase in the dynamic pressure of the solar wind. A simulation result is found to support this interpretation. The dynamic pressure model for a comet can be compared with the mechanism of a possible geotail disturbance during a spacecraft triggered auroral substorm.

  1. Early sepsis detection in critical care patients using multiscale blood pressure and heart rate dynamics.

    Science.gov (United States)

    Shashikumar, Supreeth P; Stanley, Matthew D; Sadiq, Ismail; Li, Qiao; Holder, Andre; Clifford, Gari D; Nemati, Shamim

    2017-08-16

    Sepsis remains a leading cause of morbidity and mortality among intensive care unit (ICU) patients. For each hour treatment initiation is delayed after diagnosis, sepsis-related mortality increases by approximately 8%. Therefore, maximizing effective care requires early recognition and initiation of treatment protocols. Antecedent signs and symptoms of sepsis can be subtle and unrecognizable (e.g., loss of autonomic regulation of vital signs), causing treatment delays and harm to the patient. In this work we investigated the utility of high-resolution blood pressure (BP) and heart rate (HR) times series dynamics for the early prediction of sepsis in patients from an urban, academic hospital, meeting the third international consensus definition of sepsis (sepsis-III) during their ICU admission. Using a multivariate modeling approach we found that HR and BP dynamics at multiple time-scales are independent predictors of sepsis, even after adjusting for commonly measured clinical values and patient demographics and comorbidities. Earlier recognition and diagnosis of sepsis has the potential to decrease sepsis-related morbidity and mortality through earlier initiation of treatment protocols. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Permeability and pressure measurements in Lesser Antilles submarine slides: Evidence for pressure-driven slow-slip failure

    Science.gov (United States)

    Hornbach, Matthew J.; Manga, Michael; Genecov, Michael; Valdez, Robert; Miller, Peter; Saffer, Demian; Adelstein, Esther; Lafuerza, Sara; Adachi, Tatsuya; Breitkreuz, Christoph; Jutzeler, Martin; Le Friant, Anne; Ishizuka, Osamu; Morgan, Sally; Slagle, Angela; Talling, Peter J.; Fraass, Andrew; Watt, Sebastian F. L.; Stroncik, Nicole A.; Aljahdali, Mohammed; Boudon, Georges; Fujinawa, Akihiko; Hatfield, Robert; Kataoka, Kyoko; Maeno, Fukashi; Martinez-Colon, Michael; McCanta, Molly; Palmer, Martin; Stinton, Adam; Subramanyam, K. S. V.; Tamura, Yoshihiko; Villemant, Benoît; Wall-Palmer, Deborah; Wang, Fei

    2015-12-01

    Recent studies hypothesize that some submarine slides fail via pressure-driven slow-slip deformation. To test this hypothesis, this study derives pore pressures in failed and adjacent unfailed deep marine sediments by integrating rock physics models, physical property measurements on recovered sediment core, and wireline logs. Two drill sites (U1394 and U1399) drilled through interpreted slide debris; a third (U1395) drilled into normal marine sediment. Near-hydrostatic fluid pressure exists in sediments at site U1395. In contrast, results at both sites U1394 and U1399 indicate elevated pore fluid pressures in some sediment. We suggest that high pore pressure at the base of a submarine slide deposit at site U1394 results from slide shearing. High pore pressure exists throughout much of site U1399, and Mohr circle analysis suggests that only slight changes in the stress regime will trigger motion. Consolidation tests and permeability measurements indicate moderately low (~10-16-10-17 m2) permeability and overconsolidation in fine-grained slide debris, implying that these sediments act as seals. Three mechanisms, in isolation or in combination, may produce the observed elevated pore fluid pressures at site U1399: (1) rapid sedimentation, (2) lateral fluid flow, and (3) shearing that causes sediments to contract, increasing pore pressure. Our preferred hypothesis is this third mechanism because it explains both elevated fluid pressure and sediment overconsolidation without requiring high sedimentation rates. Our combined analysis of subsurface pore pressures, drilling data, and regional seismic images indicates that slope failure offshore Martinique is perhaps an ongoing, creep-like process where small stress changes trigger motion.

  3. Application of nonlinear dynamic techniques to high pressure plasma jets

    Science.gov (United States)

    Ghorui, S.; Das, A. K.

    2010-02-01

    Arcs and arc plasmas have been known and used for welding, cutting, chemical synthesis and multitude of other industrial applications for more than hundred years. Though a copious source of heat, light and active species, plasma arc is inherently unstable, turbulent and difficult to control. During recent years, primarily driven by the need of new and energy efficient materials processing, various research groups around the world have been studying new and innovative ways of looking at the issues related to arc dynamics, arc stabilization, species non equilibrium, flow and heat transfer in a stabilized arc plasma device. In this context, experimental determination of nature of arc instabilities using tools of non-linear dynamics, theoretical model formulation, prediction of instability behavior under given operating conditions and possible control methods for the observed instabilities in arcs are reviewed. Space selective probing of the zones inside arc plasma devices without disturbing the system is probably the best way to identify the originating zone of instabilities inside such devices. Existence of extremely high temperature and inaccessibility to direct experimentations due to mechanical obstructions make this task extremely difficult. Probing instabilities in otherwise inaccessible inner regions of the torches, using binary gas mixture as plasma gas is a novel technique that primarily rests on a process known as demixing in arcs. Once a binary gas mixture enters the constricted plasma column, the demixing process sets in causing spatial variations for each of the constituent gases depending on the diffusion coefficients and the gradient of the existing temperature field. By varying concentrations of the constituent gases in the feeding line, it is possible to obtain spatial variations of the plasma composition in a desired manner, enabling spatial probing of the associated zones. Detailed compositional description of different zones inside the torch may be

  4. Pressure Measurement Techniques for Abdominal Hypertension: Conclusions from an Experimental Model

    Directory of Open Access Journals (Sweden)

    Sascha Santosh Chopra

    2015-01-01

    Full Text Available Introduction. Intra-abdominal pressure (IAP measurement is an indispensable tool for the diagnosis of abdominal hypertension. Different techniques have been described in the literature and applied in the clinical setting. Methods. A porcine model was created to simulate an abdominal compartment syndrome ranging from baseline IAP to 30 mmHg. Three different measurement techniques were applied, comprising telemetric piezoresistive probes at two different sites (epigastric and pelvic for direct pressure measurement and intragastric and intravesical probes for indirect measurement. Results. The mean difference between the invasive IAP measurements using telemetric pressure probes and the IVP measurements was −0.58 mmHg. The bias between the invasive IAP measurements and the IGP measurements was 3.8 mmHg. Compared to the realistic results of the intraperitoneal and intravesical measurements, the intragastric data showed a strong tendency towards decreased values. The hydrostatic character of the IAP was eliminated at high-pressure levels. Conclusion. We conclude that intragastric pressure measurement is potentially hazardous and might lead to inaccurately low intra-abdominal pressure values. This may result in missed diagnosis of elevated abdominal pressure or even ACS. The intravesical measurements showed the most accurate values during baseline pressure and both high-pressure plateaus.

  5. Dynamic Increase Factors for High Performance Concrete in Compression using Split Hopkinson Pressure Bar

    DEFF Research Database (Denmark)

    Riisgaard, Benjamin; Ngo, Tuan; Mendis, Priyan

    2007-01-01

    This paper provides dynamic increase factors (DIF) in compression for two different High Performance Concretes (HPC), 100 MPa and 160 MPa, respectively. In the experimental investigation 2 different Split Hopkinson Pressure Bars are used in order to test over a wide range of strain rates, 100 sec1...... to 700 sec-1. The results are compared with the CEB Model Code and the Spilt Hopkinson Pressure Bar technique is briefly de-scribed....

  6. Molecular Dynamical Simulation of Water/Ice Phase Transitions within Carbon Nanotubes under Various Pressures

    Institute of Scientific and Technical Information of China (English)

    YIN Bing; DONG Shun-Le

    2009-01-01

    A molecular dynamics simulation is performed for water confined within carbon nanotubes with diameters 11.00 (A) and 12.38 (A).Under pressures from 0.1 MPa to 500MPa the simulations are carried out by cooling from 300K to 240 K.Water molecules tend to transform from disordered to ordered with different configurations (square,pentagonal,hexagonal and hexagonal plus a chain).It is concluded that denser structures may appear under high pressures.

  7. Dynamics of apokamp-type atmospheric pressure plasma jets

    Science.gov (United States)

    Sosnin, Eduard A.; Panarin, Victor A.; Skakun, Victor S.; Baksht, Evgeny Kh.; Tarasenko, Victor F.

    2017-02-01

    The paper describes a new discharge source of atmospheric pressure plasma jets (APPJs) in air with no gas supply through the discharge region. In this discharge mode, plasma jets develop from the bending point of a bright current channel between two electrodes and are therefore termed an apokamp (from Greek `off' and `bend'). The apokamp can represent single plasma jets of length up 6 cm or several jets, and the temperature of such jets can range from more than 1000 °C at their base to 100-250 °C at their tip. Apokamps are formed at maximum applied voltage of positive polarity, provided that the second electrode is capacitively decoupled with ground. According to high-speed photography with time resolution from several nanoseconds to several tens of nanoseconds, the apokamp consists of a set of plasma bullets moving with a velocity of 100-220 km/s, which excludes the convective mechanism of plasma decay. Estimates on a 100-ns scale show that the near-electrode zones and the zones from which apokamps develop are close in temperature.

  8. Pilot study: Assessing repeatability of the EcoWalk platform resistive pressure sensors to measure plantar pressure during barefoot standing

    Science.gov (United States)

    Zequera, Martha; Perdomo, Oscar; Wilches, Carlos; Vizcaya, Pedro

    2013-06-01

    Plantar pressure provides useful information to assess the feet's condition. These systems have emerged as popular tools in clinical environment. These systems present errors and no compensation information is presented by the manufacturer, leading to uncertainty in the measurements. Ten healthy subjects, 5 females and 5 males, were recruited. Lateral load distribution, antero-posterior load distribution, average pressure, contact area, and force were recorded. The aims of this study were to assess repeatability of the EcoWalk system and identify the range of pressure values observed in the normal foot. The coefficient of repeatability was less than 4% for all parameters considered.

  9. MD1405: Demonstration of forced dynamic aperture measurements at injection

    CERN Document Server

    Carlier, Felix Simon; Persson, Tobias Hakan Bjorn; Tomas Garcia, Rogelio; CERN. Geneva. ATS Department

    2017-01-01

    Accurate measurements of dynamic aperture become more important for the LHC as it advances into increasingly nonlinear regimes of operations, as well as for the High Luminosity LHC where machine nonlinearities will have a significantly larger impact. Direct dynamic aperture measurements at top energy in the LHC are challenging, and conventional single kick methods are not viable. Dynamic aperture measurements under forced oscillation of AC dipoles have been proposed as s possible alternative observable. A first demonstration of forced DA measurements at injections energy is presented.

  10. new method to evaluate relative efficiency measure in dynamic DEA

    Directory of Open Access Journals (Sweden)

    Maryam Reshadi

    2014-10-01

    Full Text Available As known in data envelopment analysis literature, TDT measure has been used to get the relative efficiency measure of decision making units. Then, the aim of this paper is to extend TDT measure into the dynamic framework of data envelopment analysis to get the dynamic relative efficiency measure by which units' productivity would be evaluated exactly on an assessment window. To do this, it is needed firstly to identify some factors named link factors bearing truly and exactly connectivity between time periods of an assessment window to develop an accurate dynamic framework of data envelopment analysis.

  11. Measurement of pleural pressure swings with a fluid-filled esophageal catheter vs pulmonary artery occlusion pressure.

    Science.gov (United States)

    Verscheure, S; Massion, P B; Gottfried, S; Goldberg, P; Samy, L; Damas, P; Magder, S

    2017-02-01

    Pleural pressure measured with esophageal balloon catheters (Peso) can guide ventilator management and help with the interpretation of hemodynamic measurements, but these catheters are not readily available or easy to use. We tested the utility of an inexpensive, fluid-filled esophageal catheter (Peso) by comparing respiratory-induced changes in pulmonary artery occlusion (Ppao), central venous (CVP), and Peso pressures. We studied 30 patients undergoing elective cardiac surgery who had pulmonary artery and esophageal catheters in place. Proper placement was confirmed by chest compression with airway occlusion. Measurements were made during pressure-regulated volume control (VC) and pressure support (PS) ventilation. The fluid-filled esophageal catheter provided a high-quality signal. During VC and PS, change in Ppao (∆Ppao) was greater than ∆Peso (bias = -2 mm Hg) indicating an inspiratory increase in cardiac filling. During VC, ∆CVP bias was 0 indicating no change in right heart filling, but during PS, CVP fell less than Peso indicating an inspiratory increase in filling. Peso measurements detected activation of expiratory muscles, development of non-west zone 3 lung conditions during inspiration, and ventilator-triggered inspiratory efforts. A fluid-filled esophageal catheter provides a high-quality, easily accessible, and inexpensive measure of change in pleural pressure and provided insights into patient-ventilator interactions. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. Dynamic baroreflex control of blood pressure: influence of the heart vs. peripheral resistance.

    Science.gov (United States)

    Liu, Huang-Ku; Guild, Sarah-Jane; Ringwood, John V; Barrett, Carolyn J; Leonard, Bridget L; Nguang, Sing-Kiong; Navakatikyan, Michael A; Malpas, Simon C

    2002-08-01

    The aim in the present experiments was to assess the dynamic baroreflex control of blood pressure, to develop an accurate mathematical model that represented this relationship, and to assess the role of dynamic changes in heart rate and stroke volume in giving rise to components of this response. Patterned electrical stimulation [pseudo-random binary sequence (PRBS)] was applied to the aortic depressor nerve (ADN) to produce changes in blood pressure under open-loop conditions in anesthetized rabbits. The stimulus provided constant power over the frequency range 0-0.5 Hz and revealed that the composite systems represented by the central nervous system, sympathetic activity, and vascular resistance responded as a second-order low-pass filter (corner frequency approximately 0.047 Hz) with a time delay (1.01 s). The gain between ADN and mean arterial pressure was reasonably constant before the corner frequency and then decreased with increasing frequency of stimulus. Although the heart rate was altered in response to the PRBS stimuli, we found that removal of the heart's ability to contribute to blood pressure variability by vagotomy and beta(1)-receptor blockade did not significantly alter the frequency response. We conclude that the contribution of the heart to the dynamic regulation of blood pressure is negligible in the rabbit. The consequences of this finding are examined with respect to low-frequency oscillations in blood pressure.

  13. Oscillometric measurement of systolic and diastolic blood pressures validated in a physiologic mathematical model

    Directory of Open Access Journals (Sweden)

    Babbs Charles F

    2012-08-01

    Full Text Available Abstract Background The oscillometric method of measuring blood pressure with an automated cuff yields valid estimates of mean pressure but questionable estimates of systolic and diastolic pressures. Existing algorithms are sensitive to differences in pulse pressure and artery stiffness. Some are closely guarded trade secrets. Accurate extraction of systolic and diastolic pressures from the envelope of cuff pressure oscillations remains an open problem in biomedical engineering. Methods A new analysis of relevant anatomy, physiology and physics reveals the mechanisms underlying the production of cuff pressure oscillations as well as a way to extract systolic and diastolic pressures from the envelope of oscillations in any individual subject. Stiffness characteristics of the compressed artery segment can be extracted from the envelope shape to create an individualized mathematical model. The model is tested with a matrix of possible systolic and diastolic pressure values, and the minimum least squares difference between observed and predicted envelope functions indicates the best fit choices of systolic and diastolic pressure within the test matrix. Results The model reproduces realistic cuff pressure oscillations. The regression procedure extracts systolic and diastolic pressures accurately in the face of varying pulse pressure and arterial stiffness. The root mean squared error in extracted systolic and diastolic pressures over a range of challenging test scenarios is 0.3 mmHg. Conclusions A new algorithm based on physics and physiology allows accurate extraction of systolic and diastolic pressures from cuff pressure oscillations in a way that can be validated, criticized, and updated in the public domain.

  14. Dynamic Wave Pressures on Deeply Embedded Large Cylindrical Structures due to Random Waves

    Institute of Scientific and Technical Information of China (English)

    刘海笑; 唐云; 周锡礽

    2003-01-01

    The response of dynamic wave pressures on structures would be more complicated and bring about new phenomena under the dynamic interaction between soil and structure. In order to better understand the response characteristics on deeply embedded large cylindrical structures under random waves, and accordingly to offer valuable findings for engineering, the authors designed wave flume experiments to investigate comparatively dynamic wave pressures on a single and on continuous cylinders with two different embedment depths in response to two wave spectra.The time histories of the water surface elevation and the corresponding dynamic wave pressures exerted on the cylinder were analyzed in the frequency domain. By calculating the transfer function and spectral density for dynamic wave pressures along the height and around the circumference of the cylinder, experimental results of the single cylinder were compared with the theoretical results based on the linear diffraction theory, and detailed comparisons were also carried out between the single and continuous cylinders. Some new findings and the corresponding analysis are reported in present paper. The investigation on continuous cylinders will be used in particular for reference in engineering applications because information is scarce on studying such kind of problem both analytically and experimentally.

  15. Dynamic Shock Compression of Copper to Multi-Megabar Pressure

    Science.gov (United States)

    Haill, T. A.; Furnish, M. D.; Twyeffort, L. L.; Arrington, C. L.; Lemke, R. W.; Knudson, M. D.; Davis, J.-P.

    2015-11-01

    Copper is an important material for a variety of shock and high energy density applications and experiments. Copper is used as a standard reference material to determine the EOS properties of other materials. The high conductivity of copper makes it useful as an MHD driver layer in high current dynamic materials experiments on Sandia National Laboratories Z machine. Composite aluminum/copper flyer plates increase the dwell time in plate impact experiments by taking advantage of the slower wave speeds in copper. This presentation reports on recent efforts to reinstate a composite Al/Cu flyer capability on Z and to extend the range of equation-of-state shock compression data through the use of hyper-velocity composite flyers and symmetric planar impact with copper targets. We will present results from multi-dimensional ALEGRA MHD simulations, as well as experimental designs and methods of composite flyer fabrication. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, for the U.S. DOE's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  16. Simultaneous Infrared And Pressure Measurements Of Crossflow Instability Modes For HIFiRE 5 (POSTPRINT)

    Science.gov (United States)

    2017-07-01

    AFRL-RQ-WP-TP-2017-0099 SIMULTANEOUS INFRARED AND PRESSURE MEASUREMENTS OF CROSSFLOW INSTABILITY MODES FOR HIFiRE-5 (POSTPRINT) Matthew...Postprint 01 April 2015 – 01 January 2016 4. TITLE AND SUBTITLE SIMULTANEOUS INFRARED AND PRESSURE MEASUREMENTS OF CROSSFLOW INSTABILITY MODES FOR...elevated freestream noise levels. Simultaneous measurements were made using an infrared camera and 22 pressure sensors mounted flush with the model

  17. [Mobile Health: IEEE Standard for Wearable Cuffless Blood Pressure Measuring Devices].

    Science.gov (United States)

    Zhou, Xia; Wu, Wenli; Bao, Shudi

    2015-07-01

    IEEE Std 1708-2014 breaks through the traditional standards of cuff based blood pressure measuring devices and establishes a normative definition of wearable cuffless blood pressure measuring devices and the objective performance evaluation of this kind of devices. This study firstly introduces the background of the new standard. Then, the standard details will be described, and the impact of cuffless blood pressure measuring devices with the new standard on manufacturers and end users will be addressed.

  18. ON THE USEFULNESS OF FINGER BLOOD-PRESSURE MEASUREMENTS FOR STUDIES ON MENTAL WORKLOAD

    NARCIS (Netherlands)

    VELDMAN, JBP; RUDDEL, H; ROBBE, HWJ; Mulder, Lambertus; Mulder, Gysbertus

    1991-01-01

    Two experiments were conducted to explore the usefulness of the Penaz method for non-invasive, continuous finger blood pressure measurements during mental stress testing. In the first study, blood pressure was measured with the Penaz method, in the second it was measured intra-arterially. Two differ

  19. Non-invasive measurement of pressure gradients using ultrasound

    DEFF Research Database (Denmark)

    Olesen, Jacob Bjerring; Traberg, Marie Sand; Pihl, Michael Johannes

    2013-01-01

    A non-invasive method for estimating 2-D pressure gradients from ultrasound vector velocity data is presented. The method relies on in-plane vector velocity fields acquired using the Transverse Oscillation method. The pressure gradients are estimated by applying the Navier-Stokes equations...... Medical 2202 UltraView Pro Focus scanner. The results are validated through finite element simulations of the carotid flow model where the geometry is determined from MR images. This proof of concept study was conducted at nine ultrasound frames per second. Estimated pressure gradients along...... the longitudinal direction of the constriction varied from 0 kPa/m to 10 kPa/m with a normalized bias of -9.1% for the axial component and -7.9% for the lateral component. The relative standard deviation of the estimator, given in reference to the peak gradient, was 28.4% in the axial direction and 64...

  20. Screening blood pressure measurement in children: are we saving lives?

    Science.gov (United States)

    Brady, Tammy M; Redwine, Karen M; Flynn, Joseph T

    2014-06-01

    Blood Pressure screening in children and adolescents is currently recommended by several prominent medical organizations, including the American Heart Association, the National High Blood Pressure Education Program, the National Heart, Lung, and Blood Institute, the European Society of Hypertension, and the American Academy of Pediatrics. This practice was recently subject to intense scientific review by the U.S. Preventive Services Task Force. The conclusion of the Task Force was that "current evidence is insufficient to assess the balance of benefits and harms of screening for primary hypertension in asymptomatic children and adolescents." This commentary provides an alternate interpretation of current evidence for blood pressure screening in children and adolescents and highlights its importance as a part of routine medical care.

  1. A Comparison of Measured and Predicted Wave-Impact Pressures from Breaking and Non-breaking Waves

    CERN Document Server

    Fullerton, Anne M; Brewton, Susan; Brucker, Kyle A; O'Shea, Thomas T; Dommermuth, Douglas G

    2014-01-01

    Impact loads from waves on vessels and coastal structures are complex and may involve wave breaking, which has made these loads difficult to estimate numerically or empirically. Results from previous experiments have shown a wide range of forces and pressures measured from breaking and nonbreaking waves, with no clear trend between wave characteristics and the localized forces and pressures that they generate. In 2008, a canonical breaking wave impact data set was obtained at the Naval Surface Warfare Center, Carderock Division, by measuring the distribution of impact pressures of incident nonbreaking and breaking waves on one face of a cube. This experimental effort was sponsored by the Office of Naval Research (ONR), under the Dynamics of Interacting Platforms Program, Program Manager Dr. Ron Joslin. The effects of wave height, wavelength, face orientation, face angle, and submergence depth were investigated. Additionally, a limited number of runs were made at low forward speeds, ranging from about 0.5 to 2...

  2. Development of a pressure based vortex-shedding meter: measuring unsteady mass-flow in variable density gases

    Science.gov (United States)

    Ford, C. L.; Winroth, M.; Alfredsson, P. H.

    2016-08-01

    An entirely pressure-based vortex-shedding meter has been designed for use in practical time-dependent flows. The meter is capable of measuring mass-flow rate in variable density gases in spite of the fact that fluid temperature is not directly measured. Unlike other vortex meters, a pressure based meter is incredibly robust and may be used in industrial type flows; an environment wholly unsuitable for hot-wires for example. The meter has been tested in a number of static and dynamic flow cases, across a range of mass-flow rates and pressures. The accuracy of the meter is typically better than about 3% in a static flow and resolves the fluctuating mass-flow with an accuracy that is better than or equivalent to a hot-wire method.

  3. Risk evaluation on the basis of pressure rate measured by automatic pressure tracking adiabatic calorimeter.

    Science.gov (United States)

    Iwata, Yusaku; Koseki, Hiroshi

    2008-11-15

    An automatic pressure tracking adiabatic calorimeter (APTAC) had been employed to obtain the thermokinetic and the vapor pressure data during runaway reactions. The APTAC is an adiabatic calorimeter with a large-scale sample mass and low thermal inertia, and is an extremely useful tool for assessing thermal hazards of reactive chemicals. The data obtained by the APTAC are important information for the design of the safe industrial process. The thermodynamics parameters and the gas production were discussed on the basis of the experimental data of various concentrations and weights of di-tert-butyl peroxide (DTBP)/toluene solution for the purpose of investigating the properties of the APTAC data. The thermal decomposition of DTBP was studied on the basis of the temperature data and the pressure data obtained by the APTAC. The activation energy and the frequency factor of DTBP are nearly constant and the same as the literature values in the concentrations between 20 and 60 wt.%. The pressure rise due to gas production is important data for designing the relief vent of a reactor. The time history of the gas production was investigated with various weights and concentrations. The total gas production index, which had the vapor pressure correction, was 1.0 in the decomposition of DTBP.

  4. Static and dynamic stress analyses of the prototype high head Francis runner based on site measurement

    Science.gov (United States)

    Huang, X.; Oram, C.; Sick, M.

    2014-03-01

    More efforts are put on hydro-power to balance voltage and frequency within seconds for primary control in modern smart grids. This requires hydraulic turbines to run at off-design conditions. especially at low load or speed-no load. Besides. the tendency of increasing power output and decreasing weight of the turbine runners has also led to the high level vibration problem of the runners. especially high head Francis runners. Therefore. it is important to carry out the static and dynamic stress analyses of prototype high head Francis runners. This paper investigates the static and dynamic stresses on the prototype high head Francis runner based on site measurements and numerical simulations. The site measurements are performed with pressure transducers and strain gauges. Based on the measured results. computational fluid dynamics (CFD) simulations for the flow channel from stay vane to draft tube cone are performed. Static pressure distributions and dynamic pressure pulsations caused by rotor-stator interaction (RSI) are obtained under various operating conditions. With the CFD results. static and dynamic stresses on the runner at different operating points are calculated by means of the finite element method (FEM). The agreement between simulation and measurement is analysed with linear regression method. which indicates that the numerical result agrees well with that of measurement. Furthermore. the maximum static and dynamic stresses on the runner blade are obtained at various operating points. The relations of the maximum stresses and the power output are discussed in detail. The influences of the boundary conditions on the structural behaviour of the runner are also discussed.

  5. Theoretical study on the lattice dynamics and electron-phonon interaction of vanadium under high pressures

    CERN Document Server

    Suzuki, N

    2002-01-01

    First-principles calculations are performed for the lattice dynamics and electron-phonon interaction of the body-centred-cubic (bcc) phase of solid vanadium. A remarkable phonon anomaly is found, i.e. frequencies of the transverse mode around a quarter of the GAMMA-H line show softening with increasing pressure and become imaginary at pressures higher than approx 130 GPa. The superconducting transition temperatures T sub c of bcc vanadium estimated as a function of pressure increases at first linearly with pressure, and then the rate of increase of T sub c is abated around 80 GPa. This calculated pressure dependence of T sub c shows qualitatively the same behaviour as the experimental result.

  6. Análisis entre la recirculación medida por termodilución (BTM® y la presión venosa dinámica inicial como métodos para la detección de estenosis del acceso vascular protésico Analysis of recirculation measured by thermodilution (BTM® and initial dynamic venous pressure as methods for the detection of stenosis in prosthetic vascular access

    Directory of Open Access Journals (Sweden)

    Jorge Enrique Marín González

    2012-12-01

    aparición de eventos, se encontró relación significativa con la presión venosa dinámica inicial (pIntroduction: Vascular access problems represent the highest cause of morbility and mortality in haemodialysis patients. In turn, stenosis is the main cause of dysfunctions of the prosthetic vascular access, and when this problem is not detected in time, it may lead to thrombosis. There are a number of procedures for the detection of vascular access dysfunction, ranging from physical examination, pressure and flow measurements, and non-invasive and invasive imaging tests. Initial Dynamic Venous Pressure is a simple tool for monitoring vascular access. Aims: The aim of the study is to correlate initial dynamic venous pressure and recirculation as vascular access monitoring methods in haemodialysis patients. Material and methods: A prospective assessment of 21 patients with prostheses was carried out over 1 year. Clinical signs and objective measurement parameters were recorded such as recirculation by thermodilution, initial dynamic venous pressure with a blood flow of 200 ml/min, haemostasis time and KT/V by OCM, which were compared with the findings of the imaging tests. Measurements were taken monthly, with a total of 244. Results: PTFE prostheses represented 16.6% of the vascular accesses in our unit during the period of study. The average age was 63 years, and 57% of the patients studied were women. The mean dialysis time was 225 minutes with a Kt/V by OCM of 1.44. Of the clinical signs, the one with the highest incidence was the presence of pseudoaneurysms, in 42.8%. The mean recirculation was 10.46±2.68% and initial dynamic venous pressure 94.51±19.58 mmHg. A total of 21 events were recorded: 14 fistulographies + angioplasty, 4 thromboses with surgical repair, 2 fistulographies that did not require angioplasty and one thrombosis that was not recovered. When the recirculation and initial dynamic venous pressure measurements are compared with the appearance of

  7. Dynamics of phenotypic reversibility of bacterial cells with oscillating hydrostatic pressure

    Science.gov (United States)

    Nepal, Sudip; Kumar, Pradeep

    Bacterial cells encounter and respond to physiochemical fluctuations. The response depends on the extent and type of the stresses applied. The response of bacterial cells to the fluctuating stress is relatively unknown. Here, we have studied the response of wild type Escherichia coli (E. coli) under fluctuating hydrostatic pressures ranging from 1 atm to 500 atm. High pressure acts as a stress to E. coli since these bacteria are adapted to grow optimally at atmospheric pressure. Cell division of E. coli is inhibited at high pressures resulting in increase in the length of the cells. Cell-length is reversible in nature and bacterial cells revert back to normal size on a time scale that is proportional to the strength and time of continuous pressure applied upon relaxing the high pressure condition. We have studied the dynamics of cellular reversibility of E. coli under the conditions in which continuous pressure is applied and subsequently relaxed over different time scales. We have quantified the dynamics of cellular reversibility with different relaxation times. Furthermore, we propose a model to describe the reversibility of the bacterial cell with the relaxation time. Our theoretical model fits well to the experimental data. We further

  8. Measuring Vapor Pressure with an Isoteniscope: A Hands-on Introduction to Thermodynamic Concepts

    Science.gov (United States)

    Chen, Wenqian; Haslam, Andrew J.; Macey, Andrew; Shah, Umang V.; Brechtelsbauer, Clemens

    2016-01-01

    Characterization of the vapor pressure of a volatile liquid or azeotropic mixture, and its fluid phase diagram, can be achieved with an isoteniscope and an industrial grade digital pressure sensor using the experimental method reported in this study. We describe vapor-pressure measurements of acetone and n-hexane and their azeotrope, and how the…

  9. Lectures on dynamical models for quantum measurements

    NARCIS (Netherlands)

    Nieuwenhuizen, T.M.; Perarnau-llobet, M.; Balian, R.

    2014-01-01

    In textbooks, ideal quantum measurements are described in terms of the tested system only by the collapse postulate and Born's rule. This level of description offers a rather flexible position for the interpretation of quantum mechanics. Here we analyse an ideal measurement as a process of interacti

  10. Lectures on dynamical models for quantum measurements

    NARCIS (Netherlands)

    Nieuwenhuizen, T.M.; Perarnau-llobet, M.; Balian, R.

    2014-01-01

    In textbooks, ideal quantum measurements are described in terms of the tested system only by the collapse postulate and Born's rule. This level of description offers a rather flexible position for the interpretation of quantum mechanics. Here we analyse an ideal measurement as a process of

  11. Effects of Thermal Treatment on the Dynamic Mechanical Properties of Coal Measures Sandstone

    Science.gov (United States)

    Li, Ming; Mao, Xianbiao; Cao, Lili; Pu, Hai; Mao, Rongrong; Lu, Aihong

    2016-09-01

    Many projects such as the underground gasification of coal seams and coal-bed methane mining (exploitation) widely involve the dynamic problems of coal measures sandstone achieved via thermal treatment. This study examines the dynamic mechanical properties of coal measures sandstone after thermal treatment by means of an MTS653 high-temperature furnace and Split Hopkinson pressure bar test system. Experimental results indicate that 500 °C is a transition point for the dynamic mechanical parameters of coal measures sandstone. The dynamic elastic modulus and peak strength increase linearly from 25 to 500 °C while the dynamic peak strain decreases linearly over the same temperature range. The dynamic elastic modulus and peak strength drop quickly from 500 to 800 °C, with a significant increase in the dynamic peak strain over the same temperature range. The rock mechanics are closely linked to material composition and mesoscopic structure. Analysis by X-ray diffraction and scanning electron microscopy indicate that the molecules inside the sandstone increase in density due to the thermal expansion of the material particles, which effectively improves the deformation resistance and carrying capacity of the sandstone and reduces the likelihood of axial deformation. With heat treatment that exceeds 500 °C, the dynamic mechanical properties rapidly weaken due to the decomposition of kaolinite; additionally, hot cracking of the mineral particles within the materials arises from coal sandstone internal porosity, and other defects gradually appear.

  12. Practical compensation for nonlinear dynamic thrust measurement system

    Directory of Open Access Journals (Sweden)

    Chen Lin

    2015-04-01

    Full Text Available The real dynamic thrust measurement system usually tends to be nonlinear due to the complex characteristics of the rig, pipes connection, etc. For a real dynamic measuring system, the nonlinearity must be eliminated by some adequate methods. In this paper, a nonlinear model of dynamic thrust measurement system is established by using radial basis function neural network (RBF-NN, where a novel multi-step force generator is designed to stimulate the nonlinearity of the system, and a practical compensation method for the measurement system using left inverse model is proposed. Left inverse model can be considered as a perfect dynamic compensation of the dynamic thrust measurement system, and in practice, it can be approximated by RBF-NN based on least mean square (LMS algorithms. Different weights are set for producing the multi-step force, which is the ideal input signal of the nonlinear dynamic thrust measurement system. The validity of the compensation method depends on the engine’s performance and the tolerance error 0.5%, which is commonly demanded in engineering. Results from simulations and experiments show that the practical compensation using left inverse model based on RBF-NN in dynamic thrust measuring system can yield high tracking accuracy than the conventional methods.

  13. Lateral Pressure of RC Silos with Static and Dynamic Granular Materials

    Institute of Scientific and Technical Information of China (English)

    Lingkai Meng

    2015-01-01

    This paper aims at analyzing material⁃induced lateral pressure of RC cylinder silo in both static and dynamic condition using the finite element method (FEM).In the finite element software ABAQUS, concrete material is modeled by concrete damaged plasticity model, and stored materials in silo is modeled by the hypoplastic theory.In terms of numerical model, shell elements (S4R) and solid elements (C3D8) are applied for model silo wall and stored materials respectively. The interaction between silo wall and stored materials is simulated by Coulomb friction model and penalty contact constrain provided by ABAQUS.The numerical results are verified with the existing experimental data that are designed to ensure the validation of such numerical model using FEM and it obtains good agreements between numerical results and experimental data. Then the material parameters are analyzed in both static and dynamic condition.According to the analysis, it is clear that critical friction angle, initial void ratio and minimum void ratio have an obvious effect on static lateral pressure while all the material parameters affect dynamic lateral pressure at different levels. In addition, differences of silo wall between elastic and plastic state are analyzed in dynamic condition. The numerical results show that it contributes to increasing dynamic pressure when silo wall enters into the plastic state. Finally, this paper discusses the time⁃history lateral pressure at different heights along silo wall, and analytical results indicate that larger acceleration values play main roles in producing the maximum lateral pressure at higher part of the silo wall.

  14. [Multimedia application in mobile platform for teaching the measurement of central venous pressure].

    Science.gov (United States)

    Galvão, Elizabeth Correia Ferreira; Püschel, Vilanice Alves Araújo

    2012-10-01

    This study aimed to develop and assess an application software for the teaching of the procedure Manual Measurement of the Central Venous Pressure which can be used in mobile devices. The research was conducted in three phases (Survey of needs; Methodology for multimedia application development and evaluation of the multimedia application).The multimedia was the method chosen because it favors an encouraging and dynamic environment, as it integrates images and texts into an application software available for cell phones, constituting a mobile and autonomous means for learning. The research allowed to demonstrate the feasibility of the development from this pedagogical tool and open up prospects for believing that, in Nursing education, the technology available can uncover new ways of learning in a meaningful manner.

  15. Apparatus Measures Friction In Vacuum Or Pressurized Gas

    Science.gov (United States)

    Trevathan, Joseph R.

    1996-01-01

    Friction-testing apparatus in small test chamber contains special atmosphere, which could include vacuum or pressurized gas. Provides readings indicative of friction between pin specimen and plate specimen sliding under pin in reciprocating linear motion. Pin and plate specimens made of same or different material.

  16. Operation Manual: Pressure Momentum Method of Discharge Measurement.

    Science.gov (United States)

    1984-05-01

    Scale Factors .... ............... ... A3 Al Table Al Manometer Conversion Factors Water Temperature Inches Deflection/psid, B OF Mercury, Hg * Meriam , Me...differential pressure (psid): psid = B- Specific gravity of Meriam = 2.95. Table A2 Water Density* Temperature Density3 OF slugs/ft3 32 1.940 40 1.940 50

  17. Extraction of airfoil data using PIV and pressure measurements

    DEFF Research Database (Denmark)

    Yang, Hua; Shen, Wen Zhong; Sørensen, Jens Nørkær

    2011-01-01

    Velocimetry (PIV) flow fields at different rotor azimuth positions are examined for determining sectional airfoil data. The AOA is derived locally by determining the local circulation on the blade from pressure data and subtracting the induction of the bound circulation from the local velocity. The derived...

  18. Measures of blood pressure and cognition in dialysis patients

    Science.gov (United States)

    There are few reports on the relationship of blood pressure with cognitive function in maintenance dialysis patients. The Cognition and Dialysis Study is an ongoing investigation of cognitive function and its risk factors in six Boston area hemodialysis units. In this analysis, we evaluated the rela...

  19. Measuring Blast-Related Intracranial Pressure Within the Human Head

    Science.gov (United States)

    2010-08-01

    of the data from the s ensor placed in the parietal lobe. However sensor breakage was lower than expected for a first setup: the expertise used to...connected to s ensor location in the IC pressur e profiles, as it c an be noted in all th e figures presented that had diagram s with same exposure and

  20. Test of pressure transducer for measuring cotton-mass flow

    Science.gov (United States)

    In this study, a cotton harvester yield monitor was developed based on the relationship between air pressure and the mass of seed cotton conveyed. The sensor theory was verified by laboratory tests. The sensor was tested on a cotton picker with seed cotton at two moisture contents, 5.9% and 8.5% we...