Cuff-Free Blood Pressure Estimation Using Pulse Transit Time and Heart Rate.

PubMed

Wang, Ruiping; Jia, Wenyan; Mao, Zhi-Hong; Sclabassi, Robert J; Sun, Mingui

2014-10-01

It has been reported that the pulse transit time (PTT), the interval between the peak of the R-wave in electrocardiogram (ECG) and the fingertip photoplethysmogram (PPG), is related to arterial stiffness, and can be used to estimate the systolic blood pressure (SBP) and diastolic blood pressure (DBP). This phenomenon has been used as the basis to design portable systems for continuously cuff-less blood pressure measurement, benefiting numerous people with heart conditions. However, the PTT-based blood pressure estimation may not be sufficiently accurate because the regulation of blood pressure within the human body is a complex, multivariate physiological process. Considering the negative feedback mechanism in the blood pressure control, we introduce the heart rate (HR) and the blood pressure estimate in the previous step to obtain the current estimate. We validate this method using a clinical database. Our results show that the PTT, HR and previous estimate reduce the estimated error significantly when compared to the conventional PTT estimation approach (p<0.05).

Analysis of Flame Extinguishment and Height in Low Frequency Acoustically Excited Methane Jet Diffusion Flame

NASA Astrophysics Data System (ADS)

Zong, Ruowen; Kang, Ruxue; Liu, Chen; Zhang, Zhiyang; Zhi, Youran

2018-01-01

The exploration of microgravity conditions in space is increasing and existing fire extinguishing technology is often inadequate for fire safety in this special environment. As a result, improving the efficiency of portable extinguishers is of growing importance. In this work, a visual study of the effects on methane jet diffusion flames by low frequency sound waves is conducted to assess the extinguishing ability of sound waves. With a small-scale sound wave extinguishing bench, the extinguishing ability of certain frequencies of sound waves are identified, and the response of the flame height is observed and analyzed. Results show that the flame structure changes with disturbance due to low frequency sound waves of 60-100 Hz, and quenches at effective frequencies in the range of 60-90 Hz. In this range, 60 Hz is considered to be the quick extinguishing frequency, while 70-90 Hz is the stable extinguishing frequency range. For a fixed frequency, the flame height decreases with sound pressure level (SPL). The flame height exhibits the greatest sensitivity to the 60 Hz acoustic waves, and the least to the 100 Hz acoustic waves. The flame height decreases almost identically with disturbance by 70-90 Hz acoustic waves.

Analysis of Flame Extinguishment and Height in Low Frequency Acoustically Excited Methane Jet Diffusion Flame

NASA Astrophysics Data System (ADS)

Zong, Ruowen; Kang, Ruxue; Liu, Chen; Zhang, Zhiyang; Zhi, Youran

2018-05-01

The exploration of microgravity conditions in space is increasing and existing fire extinguishing technology is often inadequate for fire safety in this special environment. As a result, improving the efficiency of portable extinguishers is of growing importance. In this work, a visual study of the effects on methane jet diffusion flames by low frequency sound waves is conducted to assess the extinguishing ability of sound waves. With a small-scale sound wave extinguishing bench, the extinguishing ability of certain frequencies of sound waves are identified, and the response of the flame height is observed and analyzed. Results show that the flame structure changes with disturbance due to low frequency sound waves of 60-100 Hz, and quenches at effective frequencies in the range of 60-90 Hz. In this range, 60 Hz is considered to be the quick extinguishing frequency, while 70-90 Hz is the stable extinguishing frequency range. For a fixed frequency, the flame height decreases with sound pressure level (SPL). The flame height exhibits the greatest sensitivity to the 60 Hz acoustic waves, and the least to the 100 Hz acoustic waves. The flame height decreases almost identically with disturbance by 70-90 Hz acoustic waves.

Measurement of Blood Pressure Using an Arterial Pulsimeter Equipped with a Hall Device

PubMed Central

Lee, Sang-Suk; Nam, Dong-Hyun; Hong, You-Sik; Lee, Woo-Beom; Son, Il-Ho; Kim, Keun-Ho; Choi, Jong-Gu

2011-01-01

To measure precise blood pressure (BP) and pulse rate without using a cuff, we have developed an arterial pulsimeter consisting of a small, portable apparatus incorporating a Hall device. Regression analysis of the pulse wave measured during testing of the arterial pulsimeter was conducted using two equations of the BP algorithm. The estimated values of BP obtained by the cuffless arterial pulsimeter over 5 s were compared with values obtained using electronic or liquid mercury BP meters. The standard deviation between the estimated values and the measured values for systolic and diastolic BP were 8.3 and 4.9, respectively, which are close to the range of values of the BP International Standard. Detailed analysis of the pulse wave measured by the cuffless radial artery pulsimeter by detecting changes in the magnetic field can be used to develop a new diagnostic algorithm for BP, which can be applied to new medical apparatus such as the radial artery pulsimeter. PMID:22319381

A portable pressure pump for microfluidic lab-on-a-chip systems using a porous polydimethylsiloxane (PDMS) sponge.

PubMed

Cha, Kyoung Je; Kim, Dong Sung

2011-10-01

In this paper, we propose a novel portable and disposable pressure pump using a porous polydimethylsiloxane (PDMS) sponge and demonstrate its application to a microfluidic lab-on-a-chip. The porous PDMS sponge was simply fabricated by a sugar leaching technique based on capillary suction of pre-cured PDMS into lumps of sugar, thereby enabling us to achieve the porous PDMS sponge composed of interconnected micropores. To indicate the characteristics of the porous PDMS sponge and pump, we measured the average porosities of them whose values were 0.64 and 0.34, respectively. A stress-strain relationship of the fabricated portable pressure pump represented a linear behavior in the compressive strain range of 0 to 20%. Within this range, a pumping volume of the pressure pump could be linearly controlled by the compressed strain. Finally, the fabricated porous PDMS pump was successfully demonstrated as a portable pressure pump for a disposable microfluidic lab-on-a-chip for efficient detection of agglutination. The proposed portable pressure pump can be potentially applicable to various disposable microfluidic lab-on-a-chip systems.

Portable fixture facilitates pressure testing of instrumentation fittings

NASA Technical Reports Server (NTRS)

Olson, G. A.

1967-01-01

Portable fixture facilitates pressure testing to detect possible leaks in instrumentation fittings mounted on tank bulkheads. It uses a vacuum cup which seals a pressure regulator adapter around one side of the fitting to be pressure tested. Leakage is detected with a gas sniffer.

A novel technique for bedside anorectal manometry in humans.

PubMed

Bharucha, A E; Stroetz, R; Feuerhak, K; Szarka, L A; Zinsmeister, A R

2015-10-01

Currently, anorectal manometry (ARM), which is used to diagnose defecatory disorders and identify anal weakness in fecal incontinence (FI) is generally conducted in specialized laboratories. Our aims were to compare anorectal functions measured with high-resolution manometry (HRM) and a novel portable manometry device. Anal pressures at rest, during squeeze, and simulated evacuation, and rectal sensation were evaluated with portable and HRM in 20 healthy women, 19 women with constipation, and 11 with FI. The relationship between anal pressures measured with portable and HRM was assessed by the concordance correlation coefficient (CCC), Bland Altman test, and paired t-tests. Anal pressures at rest (CCC 0.45; 95% CI: 0.29, 0.58) and during squeeze (CCC 0.60; 95% CI: 0.46, 0.72) measured with portable and HRM were correlated and inversely associated with the risk of FI. During simulated evacuation, the CCC for rectal pressure (0.62; 95% CI: 0.43, 0.76) was greater than that for anal pressure (CCC 0.22; 95% CI: 0.04, 0.39) and the rectoanal gradient (CCC 0.22; 95% CI: 0.02, 0.41). Rectal sensory thresholds for first sensation, the desire to defecate, and urgency measured by portable and HRM were also significantly correlated between techniques. For several parameters, differences between portable and HRM were statistically significant and the Bland Altman test was positive. Anorectal pressures and rectal sensation can be conveniently measured by portable manometry and are significantly correlated with high-resolution manometry. © 2015 John Wiley & Sons Ltd.

Seismic anisotropy and its precursory change before eruptions at Piton de la Fournaise volcano, La Réunion

NASA Astrophysics Data System (ADS)

Savage, M. K.; Ferrazzini, V.; Peltier, A.; Rivemale, E.; Mayor, J.; Schmid, A.; Brenguier, F.; Massin, F.; Got, J.-L.; Battaglia, J.; DiMuro, A.; Staudacher, T.; Rivet, D.; Taisne, B.; Shelley, A.

2015-05-01

The Piton de la Fournaise volcano exhibits frequent eruptions preceded by seismic swarms and is a good target to test hypotheses about magmatically induced variations in seismic wave properties. We use a permanent station network and a portable broadband network to compare seismic anisotropy measured via shear wave splitting with geodetic displacements, ratios of compressional to shear velocity (Vp/Vs), earthquake focal mechanisms, and ambient noise correlation analysis of surface wave velocities and to examine velocity and stress changes from 2000 through 2012. Fast directions align radially to the central cone and parallel to surface cracks and fissures, suggesting stress-controlled cracks. High Vp/Vs ratios under the summit compared with low ratios under the flank suggest spatial variations in the proportion of fluid-filled versus gas-filled cracks. Secular variations of fast directions (ϕ) and delay times (dt) between split shear waves are interpreted to sense changing crack densities and pressure. Delay times tend to increase while surface wave velocity decreases before eruptions. Rotations of ϕ may be caused by changes in either stress direction or fluid pressure. These changes usually correlate with GPS baseline changes. Changes in shear wave splitting measurements made on multiplets yield several populations with characteristic delay times, measured incoming polarizations, and fast directions, which change their proportion as a function of time. An eruption sequence on 14 October 2010 yielded over 2000 shear wave splitting measurements in a 14 h period, allowing high time resolution measurements to characterize the sequence. Stress directions from a propagating dike model qualitatively fit the temporal change in splitting.

49 CFR 178.255-12 - Pressure test.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 49 Transportation 3 2013-10-01 2013-10-01 false Pressure test. 178.255-12 Section 178.255-12... Portable Tanks § 178.255-12 Pressure test. (a) Each completed portable tank prior to application of lining... the test, and applying a pressure of 60 psig. The tank shall be capable of holding the prescribed...

49 CFR 178.274 - Specifications for UN portable tanks.

Code of Federal Regulations, 2010 CFR

2010-10-01

... and 178.277, as applicable. Design type means a portable tank or series of portable tanks made of... the top of the shell during the hydraulic pressure test equal to not less than 1.5 times the design... be designed and constructed to withstand a hydraulic test pressure of not less than 1.5 times the...

49 CFR 178.274 - Specifications for UN portable tanks.

Code of Federal Regulations, 2013 CFR

2013-10-01

... and 178.277, as applicable. Design type means a portable tank or series of portable tanks made of... the top of the shell during the hydraulic pressure test equal to not less than 1.5 times the design... be designed and constructed to withstand a hydraulic test pressure of not less than 1.5 times the...

29 CFR 1915.172 - Portable air receivers and other unfired pressure vessels.

Code of Federal Regulations, 2010 CFR

2010-07-01

..., 1963. They shall be subjected to a hydrostatic pressure test of one and one-half times the working... quarterly by a competent person. They shall be subjected yearly to a hydrostatic pressure test of one and... 29 Labor 7 2010-07-01 2010-07-01 false Portable air receivers and other unfired pressure vessels...

49 CFR 178.255-12 - Pressure test.

Code of Federal Regulations, 2010 CFR

2010-10-01

... Specifications for Portable Tanks § 178.255-12 Pressure test. (a) Each completed portable tank prior to application of lining shall be tested before being put into transportation service by completely filling the...

Portable device for detection of petit mal epilepsy

NASA Technical Reports Server (NTRS)

Smith, R. G.; Houge, J. C.; Webster, J. G.

1979-01-01

A portable device that analyzes the electroencephalogram to determine if petit mal epilepsy waveforms are present is developed and tested. Clinicians should find it useful in diagnosing seizure activity of their patients. The micropower, battery-operated, portable device indicates a seizure has occurred if three criteria are satisfied: (1) frequencies of 2.5-7 Hz, (2) large-amplitude waves, and (3) minimum number of waves per second. Levels and counts are adjustable, thus insuring high reliability against noise artifacts and permitting each subject to be individually fitted. The device has shown promise in giving the patient a possible mechanism of seizure control or suppression.

Onsite Portable Alarm System - Its Merit and Application

NASA Astrophysics Data System (ADS)

Saita, J.; Sato, T.; Nakamura, Y.

2007-12-01

Recently an existence of the earthquake early warning system (EEWS) becomes popular. In general, the EEWS will be installed in a fixed observation site and it may consist of several separated components such as a sensing portion, A/D converter, an information processing potion and so on. The processed information for warning may be transmitted to network via fixed communication line, and therefore this kind of alarm system is called as Network Alarm System. On the other hand, after the severe earthquake damage, it is very important to save the disaster victims immediately. These rescue staffs are also under the risk of aftershocks and need a local alarm not depending on the network, so this kind of alarm can be called as Onsite Alarm. But the common early warning system is too complex to set onsite temporary, and even if possible to install, the alarm is too late to receive at the epicentral area. However, the new generation earthquake early warning system FREQL can issue the P wave alarm by minimum 0.2 seconds after P wave detection. And FREQL is characterized as the unique all-in-one seismometer with power unit. At the time of the 2004 Niigata-Ken-Chuetsu earthquake, a land slide attacked a car just passing. A hyper rescue team of Tokyo Fire Department pulled the survivor, one baby, from the land slide area. During their activity the rescue team was exposed to the risk of secondary hazards caused by the aftershocks. It was clear that it is necessary to use a portable warning system to issue the onsite P wave alarm. Because FREQL was originally developed as portable equipment, Tokyo Fire Department asked us to modify it to the portable equipment with the loud sound and the light signal. In this moment, this portable FREQL has equipped in nation wide. When the hyper rescue team of Tokyo Fire Department was sent to Pakistan as a task force for rescue work of the 2005 Pakistan earthquake, the portable FREQL was used as important onsite portable warning system and P wave alarms was actually issued by three times during the rescue work. Although this is one example for the actual application of portable onsite alarm, it is possible to apply the other field as the construction field. In this presentation, Portable Onsite Alarm is discussed from views of its necessity and application.

The Impact of a Deepwater Wave on a Wall with Finite Vertical Extent

NASA Astrophysics Data System (ADS)

Wang, An; Duncan, James H.

2016-11-01

The impact of a dispersively focused 2D plunging breaker (average wave frequency 1.15 Hz) on a 2D wall that is 45 cm high and 30 cm thick is studied experimentally. The temporal evolution of the water surface profile upstream of the wall is measured with a cinematic LIF technique using frame rates up to 4,500 Hz. Impact pressures on the wall are measured simultaneously at sample rates up to 900 kHz. The wall is located horizontally 6.41 m from the wave maker in all cases and the submergence of the bottom surface of the wall is varied. It is found that the impact behavior varies dramatically with the wall submergence. When the bottom is submerged by 13.3 cm, a flip-through impact occurs. In this case, the impact evolves without wave breaking and a vertical jet is formed. When the wall is submerged by less than 4.5 cm, small-amplitude components in the wave packet interact with the bottom of the wall before the main crest arrives. Ripples reflected during this interaction modify the behavior of the incoming breaker significantly. When the bottom of the wall is located sufficiently high above the mean water level, the first interaction occurs when the undisturbed wave crest collides with the wall. The highest pressures are observed in this case. The support of the Office of Naval Research is gratefully acknowledged.

Portable Fluorescence Imaging System for Hypersonic Flow Facilities

NASA Technical Reports Server (NTRS)

Wilkes, J. A.; Alderfer, D. W.; Jones, S. B.; Danehy, P. M.

2003-01-01

A portable fluorescence imaging system has been developed for use in NASA Langley s hypersonic wind tunnels. The system has been applied to a small-scale free jet flow. Two-dimensional images were taken of the flow out of a nozzle into a low-pressure test section using the portable planar laser-induced fluorescence system. Images were taken from the center of the jet at various test section pressures, showing the formation of a barrel shock at low pressures, transitioning to a turbulent jet at high pressures. A spanwise scan through the jet at constant pressure reveals the three-dimensional structure of the flow. Future capabilities of the system for making measurements in large-scale hypersonic wind tunnel facilities are discussed.

3D Numerical Simulation of the Wave and Current Loads on a Truss Foundation of the Offshore Wind Turbine During the Extreme Typhoon Event

NASA Astrophysics Data System (ADS)

Lin, C. W.; Wu, T. R.; Chuang, M. H.; Tsai, Y. L.

2015-12-01

The wind in Taiwan Strait is strong and stable which offers an opportunity to build offshore wind farms. However, frequently visited typhoons and strong ocean current require more attentions on the wave force and local scour around the foundation of the turbine piles. In this paper, we introduce an in-house, multi-phase CFD model, Splash3D, for solving the flow field with breaking wave, strong turbulent, and scour phenomena. Splash3D solves Navier-Stokes Equation with Large-Eddy Simulation (LES) for the fluid domain, and uses volume of fluid (VOF) with piecewise linear interface reconstruction (PLIC) method to describe the break free-surface. The waves were generated inside the computational domain by internal wave maker with a mass-source function. This function is designed to adequately simulate the wave condition under observed extreme events based on JONSWAP spectrum and dispersion relationship. Dirichlet velocity boundary condition is assigned at the upper stream boundary to induce the ocean current. At the downstream face, the sponge-layer method combined with pressure Dirichlet boundary condition is specified for dissipating waves and conducting current out of the domain. Numerical pressure gauges are uniformly set on the structure surface to obtain the force distribution on the structure. As for the local scour around the foundation, we developed Discontinuous Bi-viscous Model (DBM) for the development of the scour hole. Model validations were presented as well. The force distribution under observed irregular wave condition was extracted by the irregular-surface force extraction (ISFE) method, which provides a fast and elegant way to integrate the force acting on the surface of irregular structure. From the Simulation results, we found that the total force is mainly induced by the impinging waves, and the force from the ocean current is about 2 order of magnitude smaller than the wave force. We also found the dynamic pressure, wave height, and the projection area of the structure are the main factors to the total force. Detailed results and discussion are presented as well.

New Global Art Connection: Paying Tribute to the Wave-Makers (1910-2010)

ERIC Educational Resources Information Center

Kan, Koon Hwee

2013-01-01

This paper highlights "Wave-Makers (1910--2010)", a collaborative timeline redesign project, which involves interactive and advanced web-based technology to connect and complement arts curricula at two higher education institutions, one located in China and another in the United States. Through in-depth research, video-conferencing,…

Portable tester for determining gas content within a core sample

DOEpatents

Garcia, Jr., Fred; Schatzel, Steven J.

1998-01-01

A portable tester is provided for reading and displaying the pressure of a gas released from a rock core sample stored within a sealed container and for taking a sample of the released pressurized gas for chemical analysis thereof for subsequent use in a modified direct method test which determines the volume of gas and specific type of gas contained within the core sample. The portable tester includes a pair of low and high range electrical pressure transducers for detecting a gas pressure; a pair of low and high range display units for displaying the pressure of the detected gas- a selector valve connected to the low and high range pressure transducers, a selector knob for selecting gas flow to one of the flow paths; control valve having an inlet connection to the sealed container, and outlets connected to: a sample gas canister, a second outlet port connected to the selector valve means for reading the pressure of the gas from the sealed container to either the low range or high range pressure transducers, and a connection for venting gas contained within the sealed container to the atmosphere. A battery is electrically connected to and supplies the power for operating the unit. The pressure transducers, display units, selector and control valve means and the battery is mounted to and housed within a protective casing for portable transport and use.

Portable tester for determining gas content within a core sample

DOEpatents

Garcia, F. Jr.; Schatzel, S.J.

1998-04-21

A portable tester is provided for reading and displaying the pressure of a gas released from a rock core sample stored within a sealed container and for taking a sample of the released pressurized gas for chemical analysis thereof for subsequent use in a modified direct method test which determines the volume of gas and specific type of gas contained within the core sample. The portable tester includes a pair of low and high range electrical pressure transducers for detecting a gas pressure; a pair of low and high range display units for displaying the pressure of the detected gas; a selector valve connected to the low and high range pressure transducers and a selector knob for selecting gas flow to one of the flow paths; control valve having an inlet connection to the sealed container; and outlets connected to: a sample gas canister, a second outlet port connected to the selector valve means for reading the pressure of the gas from the sealed container to either the low range or high range pressure transducers, and a connection for venting gas contained within the sealed container to the atmosphere. A battery is electrically connected to and supplies the power for operating the unit. The pressure transducers, display units, selector and control valve means and the battery is mounted to and housed within a protective casing for portable transport and use. 5 figs.

Transducer Modules for Dry-Coupled Ultrasonic Inspection of Aircraft Structures

NASA Astrophysics Data System (ADS)

Komsky, Igor N.

2004-02-01

Several types of transducer modules have been developed at Northwestern University to overcome the problems that are associated with the application of liquid or gel couplants. The modules deploy polymer films to transmit the ultrasound through a dry interface. These films are very flexible, so even with a low pressure they can be adapted to the irregular inspection surfaces. The dry-coupled transducer modules may be used for transmission and reception of both longitudinal and transverse ultrasonic waves in the MHz frequency range. The prototype modules have been integrated with the portable ultrasonic inspection units and tested on a number of aircraft structures.

Design and implementation of a smartphone-based portable ultrasound pulsed-wave Doppler device for blood flow measurement.

PubMed

Huang, Chih-Chung; Lee, Po-Yang; Chen, Pay-Yu; Liu, Ting-Yu

2012-01-01

Blood flow measurement using Doppler ultrasound has become a useful tool for diagnosing cardiovascular diseases and as a physiological monitor. Recently, pocket-sized ultrasound scanners have been introduced for portable diagnosis. The present paper reports the implementation of a portable ultrasound pulsed-wave (PW) Doppler flowmeter using a smartphone. A 10-MHz ultrasonic surface transducer was designed for the dynamic monitoring of blood flow velocity. The directional baseband Doppler shift signals were obtained using a portable analog circuit system. After hardware processing, the Doppler signals were fed directly to a smartphone for Doppler spectrogram analysis and display in real time. To the best of our knowledge, this is the first report of the use of this system for medical ultrasound Doppler signal processing. A Couette flow phantom, consisting of two parallel disks with a 2-mm gap, was used to evaluate and calibrate the device. Doppler spectrograms of porcine blood flow were measured using this stand-alone portable device under the pulsatile condition. Subsequently, in vivo portable system verification was performed by measuring the arterial blood flow of a rat and comparing the results with the measurement from a commercial ultrasound duplex scanner. All of the results demonstrated the potential for using a smartphone as a novel embedded system for portable medical ultrasound applications. © 2012 IEEE

Pressure reducing capacity of felt: a feasibility study using a new portable system with thin sensors.

PubMed

Deschamps, Kevin; Messier, Benjamin

2015-03-01

Pressure redistribution and off-loading is a vital component in the management of the foot in diabetes. In the present study, a new portable system encompassing thin piezoresistors was tested for clinical utility and efficacy with respect to a commonly used pressure relieving dressing for the foot in diabetes. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Fiber optic diffraction grating maker

DOEpatents

Deason, V.A.; Ward, M.B.

1991-05-21

A compact and portable diffraction grating maker is comprised of a laser beam, optical and fiber optics devices coupling the beam to one or more evanescent beam splitters, and collimating lenses or mirrors directing the split beam at an appropriate photosensitive material. The collimating optics, the output ends of the fiber optic coupler and the photosensitive plate holder are all mounted on an articulated framework so that the angle of intersection of the beams can be altered at will without disturbing the spatial filter, collimation or beam quality, and assuring that the beams will always intersect at the position of the plate. 4 figures.

Fiber optic diffraction grating maker

DOEpatents

Deason, Vance A.; Ward, Michael B.

1991-01-01

A compact and portable diffraction grating maker comprised of a laser beam, optical and fiber optics devices coupling the beam to one or more evanescent beam splitters, and collimating lenses or mirrors directing the split beam at an appropriate photosensitive material. The collimating optics, the output ends of the fiber optic coupler and the photosensitive plate holder are all mounted on an articulated framework so that the angle of intersection of the beams can be altered at will without disturbing the spatial filter, collimation or beam quality, and assuring that the beams will always intersect at the position of the plate.

Portable Ultrasonic Guided Wave Inspection with MACRO Fiber Composite Actuators

NASA Astrophysics Data System (ADS)

Haig, A.; Mudge, P.; Catton, P.; Balachandran, W.

2010-02-01

The development of portable ultrasonic guided wave transducer arrays that utilize Macro Fiber Composite actuators (MFCs) is described. Portable inspection equipment can make use of ultrasonic guided waves to rapidly screen large areas of many types of engineering structures for defects. The defect finding performance combined with the difficulty of application determines how much the engineering industry makes use of this non-destructive, non-disruptive technology. The developments with MFCs have the potential to make considerable improvements in both these aspects. MFCs are highly efficient because they use interdigital electrodes to facilitate the extensional, d33 displacement mode. Their fiber composite design allows them to be thin, lightweight, flexible and durable. The flexibility affords them conformance with curved surfaces, which can facilitate good mechanical coupling. The suitability of a given transducer for Long Range Ultrasonic Testing is governed by the nature and amplitude of the displacement that it excites/senses in the contact area of the target structure. This nature is explored for MFCs through directional sensitivity analysis and empirical testing. Housing methods that facilitate non-permanent coupling techniques are discussed. Finally, arrangements of arrays of MFCs for the guided wave inspection of plates and pipes are considered and some broad design criteria are given.

Robust boundary treatment for open-channel flows in divergence-free incompressible SPH

NASA Astrophysics Data System (ADS)

Pahar, Gourabananda; Dhar, Anirban

2017-03-01

A robust Incompressible Smoothed Particle Hydrodynamics (ISPH) framework is developed to simulate specified inflow and outflow boundary conditions for open-channel flow. Being purely divergence-free, the framework offers smoothed and structured pressure distribution. An implicit treatment of Pressure Poison Equation and Dirichlet boundary condition is applied on free-surface to minimize error in velocity-divergence. Beyond inflow and outflow threshold, multiple layers of dummy particles are created according to specified boundary condition. Inflow boundary acts as a soluble wave-maker. Fluid particles beyond outflow threshold are removed and replaced with dummy particles with specified boundary velocity. The framework is validated against different cases of open channel flow with different boundary conditions. The model can efficiently capture flow evolution and vortex generation for random geometry and variable boundary conditions.

S-Wave Velocity Models Under the Saudi Arabian Portable Broadband Deployment: Evidence for Lithospheric Erosion Beneath the Arabian Shield

NASA Astrophysics Data System (ADS)

Julià, J.; Ammon, C. J.; Herrmann, R. B.

2002-12-01

Models of crustal evolution strongly rely on our knowledge on the mineralogical composition of subsurface rocks, as well as pressure and temperature conditions. Direct sampling of subsurface rocks is often not possible, so that constraints have to be placed from indirect estimates of rock properties. Detailed seismic imaging of subsurface rocks has the potential for providing such constraints, and probe the extent at depth of surface geologic observations. In this study, we provide detailed S-wave velocity profiles for the crust and uppermost mantle beneath the Saudi Arabian Portable Broadband Deployment stations. Seismic velocities have been estimated from the joint inversion of receiver functions and fundamental mode group velocities. Receiver functions are sensitive to S-wave velocity contrasts and vertical travel times, and surface-wave dispersion is sensitive to vertical S-wave velocity averages, so that their combination bridge resolution gaps associated with each individual data set. Our resulting models correlate well with surface geology observations in the Arabian Shield and characterize its terranes at depth: the Asir terrane consists of a 10-km thick upper crust of 3.3~km/s overlying a lower crust with shear-wave velocities of 3.7-3.8 km/s; the Afif terrane is made of a 20-km thick upper crust with average velocity of 3.6 km/s and a lower crust with a shear-velocity of about 3.8~km/s; the Nabitah mobile belt has a gradational, 15-km thick upper crust up to 3.6 km/s overlying a gradational lower crust with velocities up to 4.0 km/s. The crust-mantle transition is sharper in terranes of continental affinity and more gradational beneath terranes of oceanic affinity. In the uppermost mantle, our models suggest a thin lid between up to 50-60 km depth overlying a low velocity zone beneath station TAIF, located close to a region of upwelling mantle material. Temperatures in the lid are estimated to be about 1000 C, which are in good agreement with independent xenolith data, and suggest that the lithosphere could be eroded to a thickness as little as 50~km under this station.

75 FR 10318 - Briggs & Stratton Power Products Group, LLC., Home Power Division, a Subsidiary of Briggs...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-03-05

... portable generators, home stand-by generators and pressure washers. New findings show that worker... portable generators, home stand-by generators and pressure washers. The amended notice applicable to TA-W... 1974, as amended. Signed in Washington, DC, this 22nd day of February 2010. Elliott S. Kushner...

A linear motor and compact cylinder-piston driver for left ventricular bypass.

PubMed

Qian, K X

1990-01-01

A simple, portable, reliable and noise-free pneumatic driver has been developed. It consists of a linear motor attached to a cylinder piston, in one unit. The motor coil is directly wound on the cylinder, and the permanent magnet is fixed to the piston. As a continuous voltage square wave is applied to the coil, the cylinder reciprocates on the piston periodically, producing air pressure and vacuum alternately. In conjunction with a locally made diaphragm pump, the driver was tested in vitro and in vivo. Results demonstrated that the device could drive the diaphragm pump and so support the circulation of an experimental animal. The driver weighs 12 kg. For 200 mmHg air pressure and -80 mmHg vacuum the power consumed is 30 W. Its noise is about 30 dB, less than that of an artificial valve and pump.

High-pressure portable pneumatic drive unit.

PubMed

Hete, B F; Savage, M; Batur, C; Smith, W A; Golding, L A; Nosé, Y

1989-12-01

The left ventricular assist device (LVAD) of the Cleveland Clinic Foundation (CCF) is a single-chamber assist pump, driven by a high-pressure pneumatic cylinder. A low-cost, portable driver that will allow cardiac care patients, with a high-pressure pneumatic ventricle assist, more freedom of movement has been developed. The compact and light-weight configuration can provide periods of 2 h of freedom from a fixed position driver and does not use exotic technology.

Communicating Wave Energy: An Active Learning Experience for Students

ERIC Educational Resources Information Center

Huynh, Trongnghia; Hou, Gene; Wang, Jin

2016-01-01

We have conducted an education project to communicate the wave energy concept to high school students. A virtual reality system that combines both hardware and software is developed in this project to simulate the buoy-wave interaction. This first-of-its-kind wave energy unit is portable and physics-based, allowing students to conduct a number of…

Second harmonic generation: Effects of the multiple reflections of the fundamental and the second harmonic waves on the Maker fringes

NASA Astrophysics Data System (ADS)

Tellier, Gildas; Boisrobert, Christian

2007-11-01

The Maker fringes technique is commonly used for the determination of nonlinear optical coefficients. In this article, we present a new formulation of Maker fringes in parallel-surface samples, using boundary conditions taking into account the anisotropy of the crystal, the refractive-index dispersion, and the reflections of the fundamental and the second harmonic waves inside the material. Complete expressions for the generated second harmonic intensity are given for birefringent crystals for the case of no pump depletion. A comparison between theory and experimental results is made, showing the accuracy of our theoretical expressions.

Portable Tandem Mass Spectrometer Analyzer

DTIC Science & Technology

1991-07-01

The planned instrument was to be small enough to be portable in small vehicles and was to be able to use either an atmospheric pressure ion source or a...conventional electron impact/chemical ionization ion source. In order to accomplish these developments an atmospheric pressure ionization source was...developed for a compact, commercially available tandem quadrupole mass spectrometer. This ion source could be readily exchanged with the conventional

DOE Office of Scientific and Technical Information (OSTI.GOV)

Evans, Leland B.; Cannon, Daniel C.; Hobbs, Jacob A.

Loki-Infect 3 is a desktop application intended for use by community-level decision makers. It allows rapid construction of small-scale studies of emerging or hypothetical infectious diseases in their communities and evaluation of the potential effectiveness of various containment strategies. It was designed with an emphasis on modularity, portability, and ease of use. Our goal is to make this program freely available to community workers across the world.

Rapid prototyping of solar-powered, battery-operated, atmospheric-pressure, sugar-cube size microplasma on hybrid, 3D chips for elemental analysis of liquid microsamples using a portable optical emission spectrometer

NASA Astrophysics Data System (ADS)

Zhang, X.; Karanassios, V.

2012-06-01

A solar-powered, battery-operated, atmospheric-pressure, self-igniting microplasma the size of a sugar-cube developed on a hybrid, 3d-chip is described. Rapid prototyping of the 3d-chip; some fundamental aspects and a brief characterization of its background spectral emission using a portable, fiber-optic spectrometer are discussed.

Portable digital pressure indicator for calibrating magnetic tape recorders

NASA Technical Reports Server (NTRS)

Mccormick, Royce F.; Leighty, Bradley D.

1989-01-01

The design of a portable Digital Pressure Indicator (DPI) to be used for calibrating the pressure systems on Langley's magnetic tape recorders is described. High-speed magnetic tape recorders require pressure (0 to 20 psig) for providing an air cushion across the tape guides and a slight vacuum (30 inch H2O) for maintaining the proper number of tape loops in the advance and feed chamber. The DPI is a hand-held device that can be quickly coupled to a magnetic tape recorder and includes a two-position switch for selecting either measured pressure or vacuum, to be displayed digitally in engineering units (psig or inches H2O). The DPI is currently in use in Langley's Analysis and Computation Division.

Development of High Precision Metal Micro-Electro-Mechanical-Systems Column for Portable Surface Acoustic Wave Gas Chromatograph

NASA Astrophysics Data System (ADS)

Iwaya, Takamitsu; Akao, Shingo; Sakamoto, Toshihiro; Tsuji, Toshihiro; Nakaso, Noritaka; Yamanaka, Kazushi

2012-07-01

In the field of environmental measurement and security, a portable gas chromatograph (GC) is required for the on-site analysis of multiple hazardous gases. Although the gas separation column has been downsized using micro-electro-mechanical-systems (MEMS) technology, an MEMS column made of silicon and glass still does not have sufficient robustness and a sufficiently low fabrication cost for a portable GC. In this study, we fabricated a robust and inexpensive high-precision metal MEMS column by combining diffusion-bonded etched stainless-steel plates with alignment evaluation using acoustic microscopy. The separation performance was evaluated using a desktop GC with a flame ionization detector and we achieved the high separation performance comparable to the best silicon MEMS column fabricated using a dynamic coating method. As an application, we fabricated a palm-size surface acoustic wave (SAW) GC combining this column with a ball SAW sensor and succeeded in separating and detecting a mixture of volatile organic compounds.

Compact portable diffraction moire interferometer

DOEpatents

Deason, Vance A.; Ward, Michael B.

1989-01-01

A compact and portable moire interferometer used to determine surface deformations of an object. The improved interferometer is comprised of a laser beam, optical and fiber optics devices coupling the beam to one or more evanescent wave splitters, and collimating lenses directing the split beam at one or more specimen gratings. Observation means including film and video cameras may be used to view and record the resultant fringe patterns.

Peristaltic pump-based low range pressure sensor calibration system

NASA Astrophysics Data System (ADS)

Vinayakumar, K. B.; Naveen Kumar, G.; Nayak, M. M.; Dinesh, N. S.; Rajanna, K.

2015-11-01

Peristaltic pumps were normally used to pump liquids in several chemical and biological applications. In the present study, a peristaltic pump was used to pressurize the chamber (positive as well negative pressures) using atmospheric air. In the present paper, we discuss the development and performance study of an automatic pressurization system to calibrate low range (millibar) pressure sensors. The system includes a peristaltic pump, calibrated pressure sensor (master sensor), pressure chamber, and the control electronics. An in-house developed peristaltic pump was used to pressurize the chamber. A closed loop control system has been developed to detect and adjust the pressure leaks in the chamber. The complete system has been integrated into a portable product. The system performance has been studied for a step response and steady state errors. The system is portable, free from oil contaminants, and consumes less power compared to existing pressure calibration systems. The veracity of the system was verified by calibrating an unknown diaphragm based pressure sensor and the results obtained were satisfactory.

Peristaltic pump-based low range pressure sensor calibration system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vinayakumar, K. B.; Department of Electronic Systems Engineering, Indian Institute of Science, Bangalore 5600012; Naveen Kumar, G.

2015-11-15

Peristaltic pumps were normally used to pump liquids in several chemical and biological applications. In the present study, a peristaltic pump was used to pressurize the chamber (positive as well negative pressures) using atmospheric air. In the present paper, we discuss the development and performance study of an automatic pressurization system to calibrate low range (millibar) pressure sensors. The system includes a peristaltic pump, calibrated pressure sensor (master sensor), pressure chamber, and the control electronics. An in-house developed peristaltic pump was used to pressurize the chamber. A closed loop control system has been developed to detect and adjust the pressuremore » leaks in the chamber. The complete system has been integrated into a portable product. The system performance has been studied for a step response and steady state errors. The system is portable, free from oil contaminants, and consumes less power compared to existing pressure calibration systems. The veracity of the system was verified by calibrating an unknown diaphragm based pressure sensor and the results obtained were satisfactory.« less

Portable Cathode-Air Vapor-Feed Electrochemical Medical Oxygen Concentrator (OC)

NASA Technical Reports Server (NTRS)

Balasubramanian, Ashwin

2015-01-01

Missions on the International Space Station and future space exploration will present significant challenges to crew health care capabilities, particularly in the efficient utilization of onboard oxygen resources. Exploration vehicles will require lightweight, compact, and portable oxygen concentrators that can provide medical-grade oxygen from the ambient cabin air. Current pressure-swing adsorption OCs are heavy and bulky, require significant start-up periods, operate in narrow temperature ranges, and require a liquid water feed. Lynntech, Inc., has developed an electrochemical OC that operates with a cathode-air vapor feed, eliminating the need for a bulky onboard water supply. Lynntech's OC is smaller and lighter than conventional pressure-swing OCs, is capable of instant start-up, and operates over a temperature range of 5-80 C. Accomplished through a unique nanocomposite proton exchange membrane and catalyst technology, the unit delivers 4 standard liters per minute of humidified oxygen at 60 percent concentration. The technology enables both ambient-pressure operating devices for portable applications and pressurized (up to 3,600 psi) OC devices for stationary applications.

Compact portable diffraction moire interferometer

DOEpatents

Deason, V.A.; Ward, M.B.

1988-05-23

A compact and portable moire interferometer used to determine surface deformations of an object. The improved interferometer is comprised of a laser beam, optical and fiber optics devices coupling the beam to one or more evanescent wave splitters, and collimating lenses directing the split beam at one or more specimen gratings. Observations means including film and video cameras may be used to view and record the resultant fringe patterns. 7 figs.

Global climate change: impact of heat waves under different definitions on daily mortality in Wuhan, China.

PubMed

Zhang, Yunquan; Feng, Renjie; Wu, Ran; Zhong, Peirong; Tan, Xiaodong; Wu, Kai; Ma, Lu

2017-01-01

There was no consistent definition for heat wave worldwide, while a limited number of studies have compared the mortality effect of heat wave as defined differently. This paper aimed to provide epidemiological evidence for policy makers to determine the most appropriate definition for local heat wave warning systems. We developed 45 heat wave definitions (HWs) combining temperature indicators and temperature thresholds with durations. We then assessed the impact of heat waves under various definitions on non-accidental mortality in hot season (May-September) in Wuhan, China during 2003-2010. Heat waves defined by HW14 (daily mean temperature ≥ 99.0th percentile and duration ≥ 3 days) had the best predictive ability in assessing the mortality effects of heat wave with the relative risk of 1.63 (95% CI : 1.43, 1.89) for total mortality. The group-specific mortality risk using official heat wave definition of Chinese Meteorological Administration was much smaller than that using HW14. We also found that women, and the elderly (age ≥ 65) were more susceptible to heat wave effects which were stronger and longer lasting. These findings suggest that region specific heat wave definitions are crucial and necessary for developing efficient local heat warning systems and for providing evidence for policy makers to protect the vulnerable population.

Classical and Non-Classical Regimes of the Limited-Fetch Wave Growth and Localized Structures on the Surface of Water

DTIC Science & Technology

2013-09-30

specifying the wave-maker driving signal . The short intense envelope solitons possess vertical asymmetry similar to regular Stokes waves with the same...presented in [P1], [P2]. 2. Physical model of sea wave period from altimeter data We use the asymptotic theory of wind wave growth proposed in [R6...relationship can be used for processing altimeter data assuming the wave field to be stationary and spatially inhomogeneous. It is consistent with

Portable Planetariums Teach Science

NASA Technical Reports Server (NTRS)

2015-01-01

With the Internet proving to be the wave of the future, in the 1990s Johnson Space Center awarded grants to Rice University in Houston for developing the world's first Internet-accessible museum kiosk. Further grants were awarded to the school for creating educational software for use in homes and schools, leading to the creation of Museums Teaching Planet Earth Inc. The company has gone on to develop and sell portable planetariums and accompanying educational shows.

Miniaturised electrically actuated high pressure injection valve for portable capillary liquid chromatography.

PubMed

Li, Yan; Pace, Kirsten; Nesterenko, Pavel N; Paull, Brett; Stanley, Roger; Macka, Mirek

2018-04-01

A miniaturised high pressure 6-port injection valve has been designed and evaluated for its performance in order to facilitate the development of portable capillary high performance liquid chromatography (HPLC). The electrically actuated valve features a very small size (65 × 19 × 19mm) and light weight (33g), and therefore can be easily integrated in a miniaturised modular capillary LC system suited for portable field analysis. The internal volume of the injection valve was determined as 98 nL. The novel conical shape of the stator and rotor and the spring-loaded rotor performed well up to 32MPa (4641psi), the maximum operating pressure investigated. Suitability for application was demonstrated using a miniaturised capillary LC system applied to the chromatographic separation of a mixture of biogenic amines and common cations. The RSD (relative standard deviation) values of retention times and peak areas of 6 successive runs were 0.5-0.7% and 1.8-2.8% for the separation of biogenic amines, respectively, and 0.1-0.2% and 2.1-3.0% for the separation of cations, respectively. This performance was comparable with bench-top HPLC systems thus demonstrating the applicability of the valve for use in portable and miniaturised capillary HPLC systems. Copyright © 2017 Elsevier B.V. All rights reserved.

An Experimental Study Comparing Droplet Production by a Strong Plunging and a Weak Spilling Breaking Water Waves

NASA Astrophysics Data System (ADS)

Erinin, Martin; Wang, Dan; Towle, David; Liu, Xinan; Duncan, James

2017-11-01

In this study, the production of droplets by two mechanically generated breaking water waves is investigated in a wave tank. A strong plunging breaker and weak spilling breaker are generated repeatedly with a programmable wave maker by using two dispersively focused wave packets with the same wave maker motion profile shape (average frequency 1.15 Hz) and two overall amplitude factors. The profile histories of the breaking wave crests along the center plane of the tank are measured using cinematic laser-induced fluorescence. The droplets are measured using a high speed (650 Hz) cinematic digital in-line holographic system positioned at various locations along a horizontal plane that is 1 cm above the maximum wave crest height. The measurement plane covers the entire region in the tank where the wave breaks. The holographic system is used to obtain the droplet diameters (d, for d >100 microns) and the three components of the droplet velocities. From these measurements and counting only the droplets that are moving up, the spatio-temporal distribution of droplet generation by the two breaking waves is obtained. The main features of the droplet generation are correlated with the features and phases of the breaking process. The support of the National Science Foundation under Grant OCE0751853 from the Division of Ocean Sciences is gratefully acknowledged.

Capabilities of the Large-Scale Sediment Transport Facility

DTIC Science & Technology

2016-04-01

experiments in wave /current environments. INTRODUCTION: The LSTF (Figure 1) is a large-scale laboratory facility capable of simulating conditions...comparable to low- wave energy coasts. The facility was constructed to address deficiencies in existing methods for calculating longshore sediment...transport. The LSTF consists of a 30 m wide, 50 m long, 1.4 m deep basin. Waves are generated by four digitally controlled wave makers capable of producing

Performance evaluation of the Puritan-Bennett Crew-member portable protective breathing device as prescribed by portions of FAA Action Notice A-8150.2.

DOT National Transportation Integrated Search

1989-05-01

This study was undertaken, on request, to evaluate the performance of the Puritan-Bennett portable crew protective breathing device for contaminant leaks. O2, CO2 levels, inhalation/exhalation pressure, and inhalation temperature. Tests were conducte...

Portable medical status and treatment system

NASA Technical Reports Server (NTRS)

1981-01-01

A portable medical status and treatment system is discussed. The vital signs monitor includes electrocardiogram, respiration, temperature, blood pressure, alarm, and power subsystems, which are described. A DC defibrillator module, a radio module, and their packaging are also described. These subsystems were evaluated and the results and recommendations are presented.

40 CFR Appendix I to Part 204 - Appendix I to Part 204

Code of Federal Regulations, 2014 CFR

2014-07-01

... plane composition: Operating speed as tested: Beginning of test rpm End of test rpm Air pressure... acceptance not permitted for this number of batches. Table IV—Recommended Format for Portable Air Compressor... capacity: cfm (m3/in). Configuration identification: Category identification: Portable air compressor...

40 CFR Appendix I to Part 204 - Appendix I to Part 204

Code of Federal Regulations, 2013 CFR

2013-07-01

... plane composition: Operating speed as tested: Beginning of test rpm End of test rpm Air pressure... acceptance not permitted for this number of batches. Table IV—Recommended Format for Portable Air Compressor... capacity: cfm (m3/in). Configuration identification: Category identification: Portable air compressor...

40 CFR Appendix I to Part 204 - Appendix I to Part 204

Code of Federal Regulations, 2012 CFR

2012-07-01

... plane composition: Operating speed as tested: Beginning of test rpm End of test rpm Air pressure... acceptance not permitted for this number of batches. Table IV—Recommended Format for Portable Air Compressor... capacity: cfm (m3/in). Configuration identification: Category identification: Portable air compressor...

A Portable Double-Slit Quantum Eraser with Individual Photons

ERIC Educational Resources Information Center

Dimitrova, T. L.; Weis, A.

2011-01-01

The double-slit experiment has played an important role in physics, from supporting the wave theory of light, via the discussions of the wave-particle duality of light (and matter) to the foundations of modern quantum optics. Today it keeps playing an active role in the context of quantum optics experiments involving single photons. In this paper,…

[Research on a non-invasive pulse wave detection and analysis system].

PubMed

Li, Ting; Yu, Gang

2008-10-01

A novel non-invasive pulse wave detection and analysis system has been developed, including the software and the hardware. Bi-channel signals can be acquired, stored and shown on the screen dynamically at the same time. Pulse wave can be reshown and printed after pulse wave analysis and pulse wave velocity analysis. This system embraces a computer which is designed for fast data saving, analyzing and processing, and a portable data sampling machine which is based on a singlechip. Experimental results have shown that the system is stable and easy to use, and the parameters are calculated accurately.

Adapter assembly prevents damage to tubing during high pressure tests

NASA Technical Reports Server (NTRS)

Stinett, L. L.

1965-01-01

Portable adapter assembly prevents damage to tubing and injury to personnel when pressurizing a system or during high pressure tests. The assembly is capable of withstanding high pressure. It is securely attached to the tubing stub end and may be removed without brazing, cutting or cleaning the tube.

The reservoir-wave approach to characterize pulmonary vascular-right ventricular interactions in humans.

PubMed

Ghimire, Anukul; Andersen, Mads J; Burrowes, Lindsay M; Bouwmeester, J Christopher; Grant, Andrew D; Belenkie, Israel; Fine, Nowell M; Borlaug, Barry A; Tyberg, John V

2016-12-01

Using the reservoir-wave approach (RWA) we previously characterized pulmonary vasculature mechanics in a normal canine model. We found reflected backward-traveling waves that decrease pressure and increase flow in the proximal pulmonary artery (PA). These waves decrease right ventricular (RV) afterload and facilitate RV ejection. With pathological alterations to the pulmonary vasculature, these waves may change and impact RV performance. Our objective in this study was to characterize PA wave reflection and the alterations in RV performance in cardiac patients, using the RWA. PA pressure, Doppler-flow velocity, and pulmonary arterial wedge pressure were measured in 11 patients with exertional dyspnea. The RWA was employed to analyze PA pressure and flow; wave intensity analysis characterized PA waves. Wave-related pressure was partitioned into two components: pressures due to forward-traveling and to backward-traveling waves. RV performance was assessed by examining the work done in raising reservoir pressure and that associated with the wave components of systolic PA pressure. Wave-related work, the mostly nonrecoverable energy expended by the RV to eject blood, tended to vary directly with mean PA pressure. Where PA pressures were lower, there were pressure-decreasing/flow-increasing backward waves that aided RV ejection. Where PA pressures were higher, there were pressure-increasing/flow-decreasing backward waves that impeded RV ejection. Pressure-increasing/flow-decreasing backward waves were responsible for systolic notches in the Doppler flow velocity profiles in patients with the highest PA pressure. Pulmonary hypertension is characterized by reflected waves that impede RV ejection and an increase in wave-related work. The RWA may facilitate the development of therapeutic strategies. Copyright © 2016 the American Physiological Society.

[Experimental research on the electromagnetic radiation immunity of a kind of portable monitor].

PubMed

Yuan, Jun; Xiao, Dongping; Jian, Xin

2010-11-01

The paper is focused on a kind of portable monitor that is widely used in military hospitals. In order to study the electromagnetic radiation immunity of the monitor, the experiments of electromagnetic radiation caused by radio frequency continuous wave in reverberation chamber and by ultra wide band (UWB) electromagnetic pulse have been done. The study results show that UWB electromagnetic pulse interferes observably the operating state of the monitor. It should be paid high attention to take protective measures. The monitor tested has some electromagnetic immunity ability for radio frequency continuous wave radiation. The frequent abnormal phenomena are baseline drift and waveform distortion. The electromagnetic sensitivity of the monitor is related to the frequency of interference source. The monitor tested is most sensitive to the frequency of 390 MHz.

Thermal Index Evaluation of Local SAR in MRI-Based Head Models of Adult and Children for Portable Telephones

NASA Astrophysics Data System (ADS)

Fujiwara, Osamu; Miyamoto, Kayoko; Wang, Jianqing

Biological hazards due to radio-frequency (RF) waves result mainly from the temperature rise in tissue. It should be, therefore, clarified to what extent the RF waves of portable telephones increase the temperature-rise in human brain that includes the central part governing the body-temperature regulation function. In this paper, we calculated both the specific absorption rate (SAR) and the resultant temperature-rise for 900 MHz and 2 GHz portable telephones using the finite-difference time-domain (FDTD) method for three typical use positions, i.e., the vertical position, cheek position and tilt position. As a result, we found that there was an increase for median and 1% value of the cumulative distribution of temperature-rise in children’s brains for any use positions of the portable telephones compared to that in the adult’s brain, and also that the increasing trend in children’s brains for temperature-rise is identical to the temperature-rise trend in children’s hypothalamus. In addition, we found that the ten-gram averaged peak SAR among the adult and children heads had the same trend as that of the 0.1% value of the relatively cumulative distribution of temperature-rise, which shows that the ten-gram averaged peak SAR reflects only the localized temperature-rise in the brain surface.

Nocturnal Air Seiches in the Arizona Meteor Crater

NASA Astrophysics Data System (ADS)

Muschinski, A.; Fritts, D. C.; Zhong, S.; Oncley, S. P.

2011-12-01

The Arizona Meteor Crater near Winslow, AZ is 170 m deep, has a diameter of 1.2 km, and it has a nearly circular shape. The motivation of the Meteor Crater Experiment (METCRAX), conducted in October 2006, was to use the Meteor Crater as a natural laboratory to study atmospheric phenomena that are typical for small basins. Among other observations, high-resolution wind, temperature and pressure measurements were collected with sonics and microbarometers, respectively, during the entire month. The sensors were mounted between 0.5 m and 8.5 m AGL on seven portable towers, five of which were located within the crater and two on the crater rim. Here we report observations of nocturnal air seiches, that is, standing gravity waves associated with the time-harmonic sloshing of the cold-air pool that forms at the bottom of the crater due to radiative cooling at night. We present time series, spectra, and spectrograms of temperature, wind and pressure fluctuations that characterize those air seiches. Typical seiche periods were 15 min. We compare the observations with the time-harmonic solutions of the shallow-water equation and with numerical simulations.

Motion Tolerant Unfocused Imaging of Physiological Waveforms for Blood Pressure Waveform Estimation Using Ultrasound.

PubMed

Seo, Joohyun; Pietrangelo, Sabino J; Sodini, Charles G; Lee, Hae-Seung

2018-05-01

This paper details unfocused imaging using single-element ultrasound transducers for motion tolerant arterial blood pressure (ABP) waveform estimation. The ABP waveform is estimated based on pulse wave velocity and arterial pulsation through Doppler and M-mode ultrasound. This paper discusses approaches to mitigate the effect of increased clutter due to unfocused imaging on blood flow and diameter waveform estimation. An intensity reduction model (IRM) estimator is described to track the change of diameter, which outperforms a complex cross-correlation model (C3M) estimator in low contrast environments. An adaptive clutter filtering approach is also presented, which reduces the increased Doppler angle estimation error due to unfocused imaging. Experimental results in a flow phantom demonstrate that flow velocity and diameter waveforms can be reliably measured with wide lateral offsets of the transducer position. The distension waveform estimated from human carotid M-mode imaging using the IRM estimator shows physiological baseline fluctuations and 0.6-mm pulsatile diameter change on average, which is within the expected physiological range. These results show the feasibility of this low cost and portable ABP waveform estimation device.

Use of a portable, single-use negative pressure wound therapy device in home care patients with low to moderately exuding wounds: a case series.

PubMed

Hurd, Theresa; Trueman, Paul; Rossington, Alan

2014-03-01

Negative pressure wound therapy (NPWT) is widely used in the management of acute and chronic wounds. The purpose of this 8-week study was to evaluate outcomes of using a new canisterless, portable, single-use NPWT system in patients with wounds treated in a Canadian community healthcare setting. The device is designed to provide negative pressure at 80±20 mm Hg, 24 hours a day of continuous usage, for a maximum wear time of 7 days. Data on wound outcomes, including exudate levels, wound appearance, and wound area, were collected weekly by a Registered Nurse as part of routine practice. When treatment was discontinued, patients and nurses were asked to rate their satisfaction with the device. Data from patients who had used a conventional NPWT device to manage their wounds were retrospectively abstracted from their medical records. In the prospective study, conducted between October 2011 and July 2012, 326 patients (median age=61 years; range 17-91 years) with wounds of mixed etiology (53 pressure ulcers, 21 venous leg ulcers, 16 diabetic foot ulcers, and 15 traumatic and 221 surgical wounds) were treated for a maximum of 8 weeks with the portable NPWT device. The majority of patients (228 out of 326; 68%) achieved complete wound closure within 8 weeks of treatment. The Kaplan-Meier estimate of median time to healing of all wounds was 9 weeks. The majority of patients (318 patients, 97%) reported they were pleased or satisfied with the dressing performance. Nurses indicated satisfaction with the dressing performance for all but two patients (99%). The majority (89%) of patients managed with conventional NPWT (n=539) had an open surgical wound with moderate or high levels of exudate. Healing rates in the portable and conventional NPWT group were similar (10% to 11% per week). Portable, single-use NPWT has the potential to deliver good wound outcomes in community care settings and simplify the use of negative pressure for nurses and patients. Additional research is needed to evaluate treatment efficacy and cost effectiveness.

49 CFR 180.605 - Requirements for periodic testing, inspection and repair of portable tanks.

Code of Federal Regulations, 2012 CFR

2012-10-01

... repair of portable tanks. 180.605 Section 180.605 Transportation Other Regulations Relating to... leakage or cracks near areas of stress concentration due to cooling metal shrinkage in welding operations, sharp fillets, reversal of stresses, or otherwise. No field welding may be done except to non-pressure...

49 CFR 180.605 - Requirements for periodic testing, inspection and repair of portable tanks.

Code of Federal Regulations, 2014 CFR

2014-10-01

... repair of portable tanks. 180.605 Section 180.605 Transportation Other Regulations Relating to... leakage or cracks near areas of stress concentration due to cooling metal shrinkage in welding operations, sharp fillets, reversal of stresses, or otherwise. No field welding may be done except to non-pressure...

49 CFR 180.605 - Requirements for periodic testing, inspection and repair of portable tanks.

Code of Federal Regulations, 2011 CFR

2011-10-01

... repair of portable tanks. 180.605 Section 180.605 Transportation Other Regulations Relating to... leakage or cracks near areas of stress concentration due to cooling metal shrinkage in welding operations, sharp fillets, reversal of stresses, or otherwise. No field welding may be done except to non-pressure...

49 CFR 180.605 - Requirements for periodic testing, inspection and repair of portable tanks.

Code of Federal Regulations, 2013 CFR

2013-10-01

... repair of portable tanks. 180.605 Section 180.605 Transportation Other Regulations Relating to... leakage or cracks near areas of stress concentration due to cooling metal shrinkage in welding operations, sharp fillets, reversal of stresses, or otherwise. No field welding may be done except to non-pressure...

Sound absorption characteristics of tree bark and forest floor

Treesearch

G. Reethof; O. H. McDaniel; G. M. Heisler

1977-01-01

Results of basic research on absorption of sound by tree bark and forest floors are presented. Amount of sound absorption by tree bark was determined by laboratory experiments with bark samples in a standing-wave tube. A modified portable standing-wave tube was used to measure absorption of sound by forest floors with different moisture contents, with and without leaf...

29 CFR 1915.173 - Drums and containers.

Code of Federal Regulations, 2012 CFR

2012-07-01

...-pass to prevent rupture of the system and the escape of such hazardous liquids or gases. (c) Pressure... pressure vessels, drums and containers of 30 gallon capacity or over containing flammable or toxic liquids... (CONTINUED) OCCUPATIONAL SAFETY AND HEALTH STANDARDS FOR SHIPYARD EMPLOYMENT Portable, Unfired Pressure...

29 CFR 1915.173 - Drums and containers.

Code of Federal Regulations, 2014 CFR

2014-07-01

...-pass to prevent rupture of the system and the escape of such hazardous liquids or gases. (c) Pressure... pressure vessels, drums and containers of 30 gallon capacity or over containing flammable or toxic liquids... (CONTINUED) OCCUPATIONAL SAFETY AND HEALTH STANDARDS FOR SHIPYARD EMPLOYMENT Portable, Unfired Pressure...

29 CFR 1915.173 - Drums and containers.

Code of Federal Regulations, 2011 CFR

2011-07-01

...-pass to prevent rupture of the system and the escape of such hazardous liquids or gases. (c) Pressure... pressure vessels, drums and containers of 30 gallon capacity or over containing flammable or toxic liquids... (CONTINUED) OCCUPATIONAL SAFETY AND HEALTH STANDARDS FOR SHIPYARD EMPLOYMENT Portable, Unfired Pressure...

29 CFR 1915.173 - Drums and containers.

Code of Federal Regulations, 2013 CFR

2013-07-01

...-pass to prevent rupture of the system and the escape of such hazardous liquids or gases. (c) Pressure... pressure vessels, drums and containers of 30 gallon capacity or over containing flammable or toxic liquids... (CONTINUED) OCCUPATIONAL SAFETY AND HEALTH STANDARDS FOR SHIPYARD EMPLOYMENT Portable, Unfired Pressure...

Portable vibro-acoustic testing system for in situ microstructure characterization and metrology

NASA Astrophysics Data System (ADS)

Smith, James A.; Nichol, Corrie I.; Zuck, Larry D.; Fatemi, Mostafa

2018-04-01

There is a need in research reactors like the one at INL to inspect irradiated materials and structures. The goal of this work is to develop a portable scanning infrastructure for a material characterization technique called vibro-acoustography (VA) that has been developed by the Idaho National laboratory for nuclear applications to characterize fuel, cladding materials, and structures. The proposed VA technology is based on ultrasound and acoustic waves; however, it provides information beyond what is available from the traditional ultrasound techniques and can expand the knowledge on nuclear material characterization and microstructure evolution. This paper will report on the development of a portable scanning system that will be set up to characterize materials and components in open water reactors and canals in situ. We will show some initial laboratory results of images generated by vibro-acoustics of surrogate fuel plates and graphite structures and discuss the design of the portable system.

Development of a portable therapeutic and high intensity ultrasound system for military, medical, and research use

PubMed Central

Lewis, George K.; Olbricht, William L.

2008-01-01

We have developed a portable high power ultrasound system with a very low output impedance amplifier circuit (less than 0.3 Ω) that can transfer more than 90% of the energy from a battery supply to the ultrasound transducer. The system can deliver therapeutic acoustical energy waves at lower voltages than those in conventional ultrasound systems because energy losses owing to a mismatched impedance are eliminated. The system can produce acoustic power outputs over the therapeutic range (greater then 50 W) from a PZT-4, 1.54 MHz, and 0.75 in diameter piezoelectric ceramic. It is lightweight, portable, and powered by a rechargeable battery. The portable therapeutic ultrasound unit has the potential to replace “plug-in” medical systems and rf amplifiers used in research. The system is capable of field service on its internal battery, making it especially useful for military, ambulatory, and remote medical applications. PMID:19045903

Astronaut Carl Walz test portable foot restraint in aft cargo bay

NASA Image and Video Library

1993-09-16

STS051-98-021 (16 Sept. 1993) --- In the Space Shuttle Discovery's aft cargo bay, astronaut Carl E. Walz gets his turn on the Portable Foot Restraint (PFR). Astronauts Walz, waving to his crew mates inside Discovery's cabin, and James H. Newman each put in some time evaluating the PFR, one of the pieces of gear to be used on the Hubble Space Telescope (HST) STS-61 servicing mission (scheduled later this year) and other Shuttle missions.

Observations of tornadoes and wall clouds with a portable FM-CW Doppler radar: 1989--1990 results

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bluestein, H.B.; Unruh, W.P.

1990-01-01

The purpose of this paper is to report on our progress using a portable, 1 W,FM (frequency modulated)-CW (continuous wave) Doppler radar developed at the Los Alamos National Laboratory (LANL), to make measurements of the wind field in tornadoes and wall clouds along with simultaneous visual documentation. Results using a CW version of the radar in 1987--1988 are given in Bluestein and Unruh (1989). 18 refs., 2 figs., 1 tab.

Fast Acceleration of 2D Wave Propagation Simulations Using Modern Computational Accelerators

PubMed Central

Wang, Wei; Xu, Lifan; Cavazos, John; Huang, Howie H.; Kay, Matthew

2014-01-01

Recent developments in modern computational accelerators like Graphics Processing Units (GPUs) and coprocessors provide great opportunities for making scientific applications run faster than ever before. However, efficient parallelization of scientific code using new programming tools like CUDA requires a high level of expertise that is not available to many scientists. This, plus the fact that parallelized code is usually not portable to different architectures, creates major challenges for exploiting the full capabilities of modern computational accelerators. In this work, we sought to overcome these challenges by studying how to achieve both automated parallelization using OpenACC and enhanced portability using OpenCL. We applied our parallelization schemes using GPUs as well as Intel Many Integrated Core (MIC) coprocessor to reduce the run time of wave propagation simulations. We used a well-established 2D cardiac action potential model as a specific case-study. To the best of our knowledge, we are the first to study auto-parallelization of 2D cardiac wave propagation simulations using OpenACC. Our results identify several approaches that provide substantial speedups. The OpenACC-generated GPU code achieved more than speedup above the sequential implementation and required the addition of only a few OpenACC pragmas to the code. An OpenCL implementation provided speedups on GPUs of at least faster than the sequential implementation and faster than a parallelized OpenMP implementation. An implementation of OpenMP on Intel MIC coprocessor provided speedups of with only a few code changes to the sequential implementation. We highlight that OpenACC provides an automatic, efficient, and portable approach to achieve parallelization of 2D cardiac wave simulations on GPUs. Our approach of using OpenACC, OpenCL, and OpenMP to parallelize this particular model on modern computational accelerators should be applicable to other computational models of wave propagation in multi-dimensional media. PMID:24497950

Design of In Situ Poled Ce(3+)-Doped Electrospun PVDF/Graphene Composite Nanofibers for Fabrication of Nanopressure Sensor and Ultrasensitive Acoustic Nanogenerator.

PubMed

Garain, Samiran; Jana, Santanu; Sinha, Tridib Kumar; Mandal, Dipankar

2016-02-01

We report an efficient, low-cost in situ poled fabrication strategy to construct a large area, highly sensitive, flexible pressure sensor by electrospun Ce(3+) doped PVDF/graphene composite nanofibers. The entire device fabrication process is scalable and enabling to large-area integration. It can able to detect imparting pressure as low as 2 Pa with high level of sensitivity. Furthermore, Ce(3+)-doped PVDF/graphene nanofiber based ultrasensitive pressure sensors can also be used as an effective nanogenerator as it generating an output voltage of 11 V with a current density ∼6 nA/cm(2) upon repetitive application of mechanical stress that could lit up 10 blue light emitting diodes (LEDs) instantaneously. Furthermore, to use it in environmental random vibrations (such as wind flow, water fall, transportation of vehicles, etc.), nanogenerator is integrated with musical vibration that exhibits to power up three blue LEDs instantly that promises as an ultrasensitive acoustic nanogenerator (ANG). The superior sensing properties in conjunction with mechanical flexibility, integrability, and robustness of nanofibers enabled real-time monitoring of sound waves as well as detection of different type of musical vibrations. Thus, ANG promises to use as an ultrasensitive pressure sensor, mechanical energy harvester, and effective power source for portable electronic and wearable devices.

Patients' choice of portable folding chairs to reduce symptoms of orthostatic hypotension

NASA Technical Reports Server (NTRS)

Smit, A. A.; Wieling, W.; Opfer-Gehrking, T. L.; van Emmerik-Levelt, H. M.; Low, P. A.

1999-01-01

Patients with neurogenic orthostatic hypotension may use portable folding chairs to prevent or reduce symptoms of low blood pressure. However, a concomitant movement disorder may limit the use of these chairs in daily living. In this prospective study, 13 patients with orthostatic hypotension, balance disturbance associated with motor disability, or both examined three commercially available portable folding chairs. A questionnaire was used to document the characteristics in chair design that were relevant for satisfactory use to these patients. Armrests, seat width, and an adjustable sitting height were found to be important features of a portable folding chair. One chair was selected by 11 of 13 patients to fit most needs.

49 CFR 173.5b - Portable and mobile refrigeration systems.

Code of Federal Regulations, 2011 CFR

2011-10-01

... operations. These refrigeration systems are used at field sites to cool (pre-cool) produce before the produce... pressure vessel must be designed, manufactured, and maintained in accordance with applicable requirements... initial pressure test performed after manufacture. Additional pressure tests must be performed after any...

49 CFR 173.5b - Portable and mobile refrigeration systems.

Code of Federal Regulations, 2014 CFR

2014-10-01

... operations. These refrigeration systems are used at field sites to cool (pre-cool) produce before the produce... pressure vessel must be designed, manufactured, and maintained in accordance with applicable requirements... initial pressure test performed after manufacture. Additional pressure tests must be performed after any...

49 CFR 178.277 - Requirements for the design, construction, inspection and testing of portable tanks intended for...

Code of Federal Regulations, 2011 CFR

2011-10-01

... design pressure in the ASME Code, Section VIII (IBR, see § 171.7 of this subchapter). Holding time is the... 49 Transportation 3 2011-10-01 2011-10-01 false Requirements for the design, construction... FOR PACKAGINGS Specifications for Portable Tanks § 178.277 Requirements for the design, construction...

49 CFR 178.277 - Requirements for the design, construction, inspection and testing of portable tanks intended for...

Code of Federal Regulations, 2012 CFR

2012-10-01

... design pressure in the ASME Code, Section VIII (IBR, see § 171.7 of this subchapter). Holding time is the... 49 Transportation 3 2012-10-01 2012-10-01 false Requirements for the design, construction... FOR PACKAGINGS Specifications for Portable Tanks § 178.277 Requirements for the design, construction...

49 CFR 178.277 - Requirements for the design, construction, inspection and testing of portable tanks intended for...

Code of Federal Regulations, 2014 CFR

2014-10-01

... design pressure in the ASME Code, Section VIII (IBR, see § 171.7 of this subchapter). Holding time is the... 49 Transportation 3 2014-10-01 2014-10-01 false Requirements for the design, construction... FOR PACKAGINGS Specifications for Portable Tanks § 178.277 Requirements for the design, construction...

49 CFR 178.277 - Requirements for the design, construction, inspection and testing of portable tanks intended for...

Code of Federal Regulations, 2010 CFR

2010-10-01

... design pressure in the ASME Code, Section VIII (IBR, see § 171.7 of this subchapter). Holding time is the... 49 Transportation 2 2010-10-01 2010-10-01 false Requirements for the design, construction... FOR PACKAGINGS Specifications for Portable Tanks § 178.277 Requirements for the design, construction...

49 CFR 178.277 - Requirements for the design, construction, inspection and testing of portable tanks intended for...

Code of Federal Regulations, 2013 CFR

2013-10-01

... design pressure in the ASME Code, Section VIII (IBR, see § 171.7 of this subchapter). Holding time is the... 49 Transportation 3 2013-10-01 2013-10-01 false Requirements for the design, construction... FOR PACKAGINGS Specifications for Portable Tanks § 178.277 Requirements for the design, construction...

Sensitization of a stray-field NMR to vibrations: a potential for MR elastometry with a portable NMR sensor.

PubMed

Mastikhin, Igor; Barnhill, Marie

2014-11-01

An NMR signal from a sample in a constant stray field of a portable NMR sensor is sensitized to vibrations. The CPMG sequence is synchronized to vibrations so that the constant gradient becomes an "effective" square-wave gradient, leading to the vibration-induced phase accumulation. The integrating nature of the spot measurement, combined with the phase distribution due to a non-uniform gradient and/or a wave field, leads to a destructive interference, the drop in the signal intensity and changes in the echo train shape. Vibrations with amplitudes as small as 140 nm were reliably detected with the permanent gradient of 12.4 T/m. The signal intensity depends on the phase offset between the vibrations and the pulse sequence. This approach opens the way for performing elastometry and micro-rheology measurements with portable NMR devices beyond the walls of a laboratory. Even without synchronization, if a vibration frequency is comparable to 1/2TE of the CPMG sequence, the signal can be severely affected, making it important for potential industrial applications of stray-field NMR. Copyright © 2014 Elsevier Inc. All rights reserved.

Testing Composites

NASA Technical Reports Server (NTRS)

1981-01-01

A device for testing composites for strength characteristics has been developed by Acoustic Emission Technology Corporation. Called the Model 206AU, the system is lightweight and portable. It is comprised of three sections. The "pulser" section injects ultrasonic waves into the material under test. A receiver picks up the simulated stress waves as they pass through the material and relays the signals to the acoustic emission section, where they are electronically analyzed.

Hand-held instrument should relieve hematoma pressure

NASA Technical Reports Server (NTRS)

Raggio, L. J.; Robertson, T. L.

1967-01-01

Portable instrument relieves hematomas beneath fingernails and toenails without surgery. This device simplifies the operative procedure with an instant variable heating tip, adjustable depth settings and interchangeable tip sizes for cauterizing small areas and relieving pressurized clots.

Bench Evaluation of Four Portable Oxygen Concentrators Under Different Conditions Representing Altitudes of 2438, 4200, and 8000 m.

PubMed

Bunel, Vincent; Shoukri, Amr; Choin, Frederic; Roblin, Serge; Smith, Cindy; Similowski, Thomas; Morélot-Panzini, Capucine; Gonzalez, Jesus

2016-12-01

Bunel, Vincent, Amr Shoukri, Frederic Choin, Serge Roblin, Cindy Smith, Thomas Similowski, Capucine Morélot-Panzini, and Jésus Gonzalez. Bench evaluation of four portable oxygen concentrators under different conditions representing altitudes of 2438, 4200, and 8000 m. High Alt Med Biol. 17:370-374, 2016.-Air travel is responsible for a reduction of the partial pressure of oxygen (O 2 ) as a result of the decreased barometric pressure. This hypobaric hypoxia can be dangerous for passengers with respiratory diseases, requiring initiation or intensification of oxygen therapy during the flight. In-flight oxygen therapy can be provided by portable oxygen concentrators, which are less expensive and more practical than oxygen cylinders, but no study has evaluated their capacity to concentrate oxygen under simulated flight conditions. We tested four portable oxygen concentrators during a bench test study. The O 2 concentrations (FO 2 ) produced were measured under three different conditions: in room air at sea level, under hypoxia due to a reduction of the partial pressure of O 2 (normobaric hypoxia, which can be performed routinely), and under hypoxia due to a reduction of atmospheric pressure (hypobaric hypoxia, using a chamber manufactured by Airbus Defence and Space). The FO 2 obtained under conditions of hypobaric hypoxia (chamber) was lower than that measured in room air (0.92 [0.89-0.92] vs. 0.93 [0.92-0.94], p = 0.029), but only one portable oxygen concentrator was unable to maintain an FO 2 ≥ 0.90 (0.89 [0.89-0.89]). In contrast, under conditions of normobaric hypoxia (tent) simulating an altitude of 2438 m, none of the apparatuses tested was able to achieve an FO 2 greater than 0.76. (0.75 [0.75-0.76] vs. 0.93 [0.92-0.94], p = 0.029). Almost all portable oxygen concentrators were able to generate a sufficient quantity of O 2 at simulated altitudes of 2438 m and can therefore be used in the aircraft cabin. Unfortunately, verification of the reliability and efficacy of these devices in a patient would require a nonroutinely available technology, and no preflight test can currently be performed by using simple techniques such as hypobaric hypoxia.

Genesis of the characteristic pulmonary venous pressure waveform as described by the reservoir-wave model

PubMed Central

Bouwmeester, J Christopher; Belenkie, Israel; Shrive, Nigel G; Tyberg, John V

2014-01-01

Conventional haemodynamic analysis of pulmonary venous and left atrial (LA) pressure waveforms yields substantial forward and backward waves throughout the cardiac cycle; the reservoir wave model provides an alternative analysis with minimal waves during diastole. Pressure and flow in a single pulmonary vein (PV) and the main pulmonary artery (PA) were measured in anaesthetized dogs and the effects of hypoxia and nitric oxide, volume loading, and positive-end expiratory pressure (PEEP) were observed. The reservoir wave model was used to determine the reservoir contribution to PV pressure and flow. Subtracting reservoir pressure and flow resulted in ‘excess’ quantities which were treated as wave-related. Wave intensity analysis of excess pressure and flow quantified the contributions of waves originating upstream (from the PA) and downstream (from the LA and/or left ventricle (LV)). Major features of the characteristic PV waveform are caused by sequential LA and LV contraction and relaxation creating backward compression (i.e. pressure-increasing) waves followed by decompression (i.e. pressure-decreasing) waves. Mitral valve opening is linked to a backwards decompression wave (i.e. diastolic suction). During late systole and early diastole, forward waves originating in the PA are significant. These waves were attenuated less with volume loading and delayed with PEEP. The reservoir wave model shows that the forward and backward waves are negligible during LV diastasis and that the changes in pressure and flow can be accounted for by the discharge of upstream reservoirs. In sharp contrast, conventional analysis posits forward and backward waves such that much of the energy of the forward wave is opposed by the backward wave. PMID:25015922

Advanced User Interface Capabilities for Application on Portable Computers

DTIC Science & Technology

1992-02-01

0 060 iI 1 ........ ... r: switch_ e( pressure , switch ) r6 : pilot- valvecircuit(A, pilot valve) pilot_ valve_ circuit(B, pilot valve) r7...shutoff_valvecircwt(A, shutoff valve) shutoff_valve circuit(B, shutoff valve) r: pressure_ switch_ circuit(A, pressure switch ) pressure_ switch circuit(B... pressure switch ) r: indicator(A, pilot valve) indicator(B, pilot valve) indicator(A, shutoff valve) indicator(B, shutoff valve) indicator(A, pressure

Baffling or Baffled: Improve Your Acoustics.

ERIC Educational Resources Information Center

Abdoo, Frank B.

1981-01-01

Presents techniques for evaluating the acoustics (reverberation time, and standing waves and resonance phenomena) of a band performance room. Gives instructions for building and placing inexpensive baffles (free-standing, portable sound barriers) to correct room defects. (SJL)

Wave Engine Topping Cycle Assessment

NASA Technical Reports Server (NTRS)

Welch, Gerard E.

1996-01-01

The performance benefits derived by topping a gas turbine engine with a wave engine are assessed. The wave engine is a wave rotor that produces shaft power by exploiting gas dynamic energy exchange and flow turning. The wave engine is added to the baseline turboshaft engine while keeping high-pressure-turbine inlet conditions, compressor pressure ratio, engine mass flow rate, and cooling flow fractions fixed. Related work has focused on topping with pressure-exchangers (i.e., wave rotors that provide pressure gain with zero net shaft power output); however, more energy can be added to a wave-engine-topped cycle leading to greater engine specific-power-enhancement The energy addition occurs at a lower pressure in the wave-engine-topped cycle; thus the specific-fuel-consumption-enhancement effected by ideal wave engine topping is slightly lower than that effected by ideal pressure-exchanger topping. At a component level, however, flow turning affords the wave engine a degree-of-freedom relative to the pressure-exchanger that enables a more efficient match with the baseline engine. In some cases, therefore, the SFC-enhancement by wave engine topping is greater than that by pressure-exchanger topping. An ideal wave-rotor-characteristic is used to identify key wave engine design parameters and to contrast the wave engine and pressure-exchanger topping approaches. An aerodynamic design procedure is described in which wave engine design-point performance levels are computed using a one-dimensional wave rotor model. Wave engines using various wave cycles are considered including two-port cycles with on-rotor combustion (valved-combustors) and reverse-flow and through-flow four-port cycles with heat addition in conventional burners. A through-flow wave cycle design with symmetric blading is used to assess engine performance benefits. The wave-engine-topped turboshaft engine produces 16% more power than does a pressure-exchanger-topped engine under the specified topping constraints. Positive and negative aspects of wave engine topping in gas turbine engines are identified.

Portable Hyperbaric Chamber

NASA Technical Reports Server (NTRS)

Schneider, William C. (Inventor); Locke, James P. (Inventor); DeLaFuente, Horacio (Inventor)

2001-01-01

A portable, collapsible hyperbaric chamber was developed. A toroidal inflatable skeleton provides initial structural support for the chamber, allowing the attendant and/or patient to enter the chamber. Oval hatches mate against bulkhead rings, and the hyperbaric chamber is pressurized. The hatches seal against an o-ring, and the internal pressure of the chamber provides the required pressure against the hatch to maintain an airtight seal. In the preferred embodiment, the hyperbaric chamber has an airlock to allow the attendant to enter and exit the patient chamber during treatment. Visual communication is provided through portholes in the patient and/or airlock chamber. Life monitoring and support systems are in communication with the interior of the hyperbaric chamber and/or airlock chamber through conduits and/or sealed feed-through connectors into the hyperbaric chamber.

Experimental system for the control of surgically induced infections

NASA Technical Reports Server (NTRS)

Tevebaugh, M. D.

1971-01-01

The development tests to be performed on the experimental system are described in detail. The test equipment, conditions, and procedures are given. The portable clean room tests include assembly, collapsability, portability, and storage; laminar flow rate; static pressure; air flow pattern; and electrostatic buildup. The other tests are on the ventilation system, human factors evaluation, electrical subsystem, and material compatibility.

Portable power supply options for positive airway pressure devices.

PubMed

Riaz, Muhammad; Certal, Victor; Camacho, Macario

2015-01-01

Patients with obstructive sleep apnea (OSA) often face the challenge of how to power their positive airway pressure (PAP) devices when alternating current power supplies are not available in remote areas with lack of electricity or frequent power outages. This article elucidates portable power supply options for PAP devices with the aim to increase alternative power source awareness among medical providers. A search of scientific databases (Medline, Scopus, Web of Science, Google Scholar, and the Cochrane Library) was carried out on the topic of alternative portable power supply options for treatment of OSA. Scientific databases listed above yielded only limited results. Most articles were found via Google search. These articles were reviewed for alternative power supply options for OSA patients when alternating current is not available. The power supply options in this article include lead-acid batteries (starter, marine and deep-cycle batteries), lithium ion batteries, solar kits, battery packs, backup power systems, portable generators, and travel-size PAP devices. There are several options to power PAP devices with direct current when alternating current is not available. Knowledgeable primary care physicians especially in rural and remote areas can help OSA patients improve PAP compliance in order to mitigate morbidity and long-term complications of OSA.

Mapping of Crustal Anisotropy in the New Madrid Seismic Zone with Shear Wave Splitting

NASA Astrophysics Data System (ADS)

Martin, P.; Arroucau, P.; Vlahovic, G.

2013-12-01

Crustal anisotropy in the New Madrid seismic zone (NMSZ) is investigated by analyzing shear wave splitting measurements from local earthquake data. For the initial data set, the Center for Earthquake Research and Information (CERI) provided over 3000 events, along with 900 seismograms recorded by the Portable Array for Numerical Data Acquisition (PANDA) network. Data reduction led to a final data set of 168 and 43 useable events from the CERI and PANDA data, respectively. From this, 186 pairs of measurements were produced from the CERI data set as well as 49 from the PANDA data set, by means of the automated shear wave splitting measurement program MFAST. Results from this study identified two dominant fast polarization directions, striking NE-SW and WNW-ESE. These are interpreted to be due to stress aligned microcracks in the upper crust. The NE-SW polarization direction is consistent with the maximum horizontal stress orientation of the region and has previously been observed in the NMSZ, while the WNW-ESE polarization direction has not. Path normalized time delays from this study range from 1-33 ms/km for the CERI network data, and 2-31 ms/km for the PANDA data, giving a range of estimated differential shear wave anisotropy between 1% and 8%, with the majority of large path normalized time delays (>20 ms/km) located along the Reelfoot fault segment. The estimated differential shear wave anisotropy values from this study are higher than those previously determined in the region, and are attributed to high crack densities and high pore fluid pressures, which agree with previous results from local earthquake tomography and microseismic swarm analysis in the NMSZ.

Determining soil hydrologic characteristics on a remote forest watershed by continuous monitoring of soil water pressures, rainfall and runoff.

Treesearch

L.R. Ahuja; S. A. El-Swaify

1979-01-01

Continuous monitoring of soil-water pressures, rainfall and runoff under natural conditions was tested as a technique for determining soil hydrologic characteristics of a remote forest watershed plot. A completely battery-powered (and thus portable) pressure transducer–scanner–recorder system was assembled for monitoring of soil-water pressures in...

Digital Health: Tracking Physiomes and Activity Using Wearable Biosensors Reveals Useful Health-Related Information

PubMed Central

Zhou, Gao; Zhou, Wenyu; Schüssler-Fiorenza Rose, Sophia Miryam; Perelman, Dalia; Colbert, Elizabeth; Runge, Ryan; Rego, Shannon; Sonecha, Ria; Datta, Somalee; McLaughlin, Tracey; Snyder, Michael P.

2017-01-01

A new wave of portable biosensors allows frequent measurement of health-related physiology. We investigated the use of these devices to monitor human physiological changes during various activities and their role in managing health and diagnosing and analyzing disease. By recording over 250,000 daily measurements for up to 43 individuals, we found personalized circadian differences in physiological parameters, replicating previous physiological findings. Interestingly, we found striking changes in particular environments, such as airline flights (decreased peripheral capillary oxygen saturation [SpO2] and increased radiation exposure). These events are associated with physiological macro-phenotypes such as fatigue, providing a strong association between reduced pressure/oxygen and fatigue on high-altitude flights. Importantly, we combined biosensor information with frequent medical measurements and made two important observations: First, wearable devices were useful in identification of early signs of Lyme disease and inflammatory responses; we used this information to develop a personalized, activity-based normalization framework to identify abnormal physiological signals from longitudinal data for facile disease detection. Second, wearables distinguish physiological differences between insulin-sensitive and -resistant individuals. Overall, these results indicate that portable biosensors provide useful information for monitoring personal activities and physiology and are likely to play an important role in managing health and enabling affordable health care access to groups traditionally limited by socioeconomic class or remote geography. PMID:28081144

Bolt Stress Monitor

NASA Technical Reports Server (NTRS)

1978-01-01

In photo, an engineer is using a new Ultrasonic Bolt Stress Monitor developed by NASA's Langley Research Center to determine whether a bolt is properly tightened. A highly accurate device, the monitor is an important tool in construction of such structures as pressure vessels, bridges and power plants, wherein precise measurement of the stress on a tightened bolt is critical. Overtightened or undertightened bolts can fail and cause serious industrial accidents or costly equipment break-downs. There are a number of methods for measuring bolt stress. Most widely used and least costly is the torque wrench, which is inherently inaccurate; it does not take into account the friction between nut and bolt, which has an influence on stress. At the other end of the spectrum, there are accurate stress-measuring systems, but they are expensive and not portable. The battery-powered Langley monitor fills a need; it is inexpensive, lightweight, portable and extremely accurate because it is not subject to friction error. Sound waves are transmitted to the bolt and a return signal is received. As the bolt is tightened, it undergoes changes in resonance due to stress, in the manner that a violin string changes tone when it is tightened. The monitor measures the changes in resonance and provides a reading of real stress on the bolt. The device, patented by NASA, has aroused wide interest and a number of firms have applied for licenses to produce it for the commercial market.

Orthogonal P-wave morphology is affected by intra-atrial pressures.

PubMed

Petersson, Richard; Smith, J Gustav; Larsson, David A; Reitan, Öyvind; Carlson, Jonas; Platonov, Pyotr; Holmqvist, Fredrik

2017-12-06

It has previously been shown that the morphology of the P-wave neither depends on atrial size in healthy subjects with physiologically enlarged atria nor on the physiological anatomical variation in transverse orientation of the left atrium. The present study aimed to investigate if different pressures in the left and right atrium are associated with different P-wave morphologies. 38 patients with isolated, increased left atrial pressure, 51 patients with isolated, increased right atrial pressure and 76 patients with biatrially increased pressure were studied. All had undergone right heart catheterization and had 12-lead electrocardiographic recordings, which were transformed into vectorcardiograms for detailed P-wave morphology analysis. Normal P-wave morphology (type 1) was more common in patients with isolated increased pressure in the right atrium while abnormal P-wave morphology (type 2) was more common in the groups with increased left atrial pressure (P = 0.032). Moreover, patients with increased left atrial pressure, either isolated or in conjunction with increased right atrial pressure, had significantly more often a P-wave morphology with a positive deflection in the sagittal plane (P = 0.004). Isolated elevated right atrial pressure was associated with normal P-wave morphology while left-sided atrial pressure elevation, either isolated or in combination with right atrial pressure elevation, was associated with abnormal P-wave morphology.

Space Suit Portable Life Support System Rapid Cycle Amine Repackaging and Sub-Scale Test Results

NASA Technical Reports Server (NTRS)

Paul, Heather L.; Rivera, Fatonia L.

2010-01-01

NASA is developing technologies to meet requirements for an extravehicular activity (EVA) Portable Life Support System (PLSS) for exploration. The PLSS Ventilation Subsystem transports clean, conditioned oxygen to the pressure garment for space suit pressurization and human consumption, and recycles the ventilation gas, removing carbon dioxide, humidity, and trace contaminants. This paper provides an overview of the development efforts conducted at the NASA Johnson Space Center to redesign the Rapid Cycle Amine (RCA) canister and valve assembly into a radial flow, cylindrical package for carbon dioxide and humidity control of the PLSS ventilation loop. Future work is also discussed.

Portable wastewater flow meter

DOEpatents

Hunter, Robert M.

1999-02-02

A portable wastewater flow meter particularly adapted for temporary use at a single location in measuring the rate of liquid flow in a circular entrance conduit of a sewer manhole both under free flow and submerged, open channel conditions and under fill pipe, surcharged conditions, comprising an apparatus having a cylindrical external surface and an inner surface that constricts the flow through the apparatus in such a manner that a relationship exists between (1) the difference between the static pressure head of liquid flowing through the entrance of the apparatus and the static pressure head of liquid flowing through the constriction, and (2) the rate of liquid flow through the apparatus.

Portable wastewater flow meter

DOEpatents

Hunter, Robert M.

1990-01-01

A portable wastewater flow meter particularly adapted for temporary use at a single location in measuring the rate of liquid flow in a circular entrance conduit of a sewer manhole both under free flow and submerged, open channel conditions and under full pipe, surcharged conditions, comprising an apparatus having a cylindrical external surface and an inner surface that constricts the flow through the apparatus in such a manner that a relationship exists between (1) the difference between the static pressure head of liquid flowing through the entrance of the apparatus and the static pressure head of liquid flowing through the constriction, and (2) the rate of liquid flow through the apparatus.

A portable 12-wavelength parallel near-infrared spectral tomography (NIRST) system for efficient characterization of breast cancer during neoadjuvant chemotherapy

NASA Astrophysics Data System (ADS)

Zhao, Yan; Burger, William R.; Zhou, Mingwei; Pogue, Brian W.; Paulsen, Keith D.; Jiang, Shudong

2017-02-01

A portable, 12-wavelength hybrid frequency domain (FD) and continuous wave (CW) near-infrared spectral tomography (NIRST) system was developed for efficient characterization of breast cancer in a clinical oncology setting. Two sets of three FD and three CW measurements were acquired simultaneously. The imaging time was reduced from 90 to 55 seconds with a new gain adjustment scheme of the optical detector. The study of integrating this system into the workflow of clinical oncology practice is ongoing.

46 CFR 64.5 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-10-01

... SYSTEMS General § 64.5 Definitions. As used in this part: (a) Marine portable tank or MPT means a liquid... consisting of the absolute vapor pressure of the product at 122 °F added to the dynamic pressure, based on... maximum allowable working pressure. (f) Dynamic loading conditions means the following: (1) A loading in...

[Determination of fat, protein and DM in raw milk by portable short-wave near infrared spectrometer].

PubMed

Li, Xiao-yun; Wang, Jia-hua; Huang, Ya-wei; Han, Dong-hai

2011-03-01

Near infrared diffuse reflectance spectroscopy calibrations of fat, protein and DM in raw milk were studied with partial least-squares (PLS) regression using portable short-wave near infrared spectrometer. The results indicated that good calibrations of fat and DM were found, the correlation coefficients were all 0.98, the RMSEC were 0.187 and 0.217, RMSEP were 0.187 and 0.296, the RPDs were 5.02 and 3.20 respectively; the calibration of protein needed to be improved but can be used for practice, the correlation coefficient was 0.95, RMSEC was 0.105, RMSEP was 0.120, and RPD was 2.60. Furthermore, the measuring accuracy was improved by analyzing the correction relation of fat and DM in raw milk This study will probably provide a new on-site method for nondestructive and rapid measurement of milk.

Magnetostrictive Alternator

NASA Technical Reports Server (NTRS)

Bruder, Geoffrey A. (Inventor); Dyson, Jr., Rodger W. (Inventor)

2018-01-01

A magnetostrictive alternator configured to convert pressure waves into electrical energy is provided. It should be appreciated that the magnetostrictive alternator may be combined in some embodiments with a Stirling engine to produce electrical power. The Stirling engine creates the oscillating pressure wave and the magnetostrictive alternator converts the pressure wave into electricity. In some embodiments, the magnetostrictive alternator may include aerogel material and magnetostrictive material. The aerogel material may be configured to convert a higher amplitude pressure wave into a lower amplitude pressure wave. The magnetostrictive material may be configured to generate an oscillating magnetic field when the magnetostrictive material is compressed by the lower amplitude pressure wave.

Cold cathode vacuum gauging system

DOEpatents

Denny, Edward C.

2004-03-09

A vacuum gauging system of the cold cathode type is provided for measuring the pressure of a plurality of separate vacuum systems, such as in a gas centrifuge cascade. Each casing is fitted with a gauge tube assembly which communicates with the vacuum system in the centrifuge casing. Each gauge tube contains an anode which may be in the form of a slender rod or wire hoop and a cathode which may be formed by the wall of the gauge tube. The tube is provided with an insulated high voltage connector to the anode which has a terminal for external connection outside the vacuum casing. The tube extends from the casing so that a portable magnet assembly may be inserted about the tube to provide a magnetic field in the area between the anode and cathode necessary for pressure measurements in a cold cathode-type vacuum gauge arrangement. The portable magnetic assembly is provided with a connector which engages the external high voltage terminal for providing power to the anode within in the gauge tube. Measurement is made in the same manner as the prior cold cathode gauges in that the current through the anode to the cathode is measured as an indication of the pressure. By providing the portable magnetic assembly, a considerable savings in cost, installation, and maintenance of vacuum gauges for pressure measurement in a gas centrifuge cascade is realizable.

Portable Dew Point Mass Spectrometry System for Real-Time Gas and Moisture Analysis

NASA Technical Reports Server (NTRS)

Arkin, C.; Gillespie, Stacey; Ratzel, Christopher

2010-01-01

A portable instrument incorporates both mass spectrometry and dew point measurement to provide real-time, quantitative gas measurements of helium, nitrogen, oxygen, argon, and carbon dioxide, along with real-time, quantitative moisture analysis. The Portable Dew Point Mass Spectrometry (PDP-MS) system comprises a single quadrupole mass spectrometer and a high vacuum system consisting of a turbopump and a diaphragm-backing pump. A capacitive membrane dew point sensor was placed upstream of the MS, but still within the pressure-flow control pneumatic region. Pressure-flow control was achieved with an upstream precision metering valve, a capacitance diaphragm gauge, and a downstream mass flow controller. User configurable LabVIEW software was developed to provide real-time concentration data for the MS, dew point monitor, and sample delivery system pressure control, pressure and flow monitoring, and recording. The system has been designed to include in situ, NIST-traceable calibration. Certain sample tubing retains sufficient water that even if the sample is dry, the sample tube will desorb water to an amount resulting in moisture concentration errors up to 500 ppm for as long as 10 minutes. It was determined that Bev-A-Line IV was the best sample line to use. As a result of this issue, it is prudent to add a high-level humidity sensor to PDP-MS so such events can be prevented in the future.

Wave Shape and Impact Pressure Measurements at a Rock Coast Cliff

NASA Astrophysics Data System (ADS)

Varley, S. J.; Rosser, N. J.; Brain, M.; Vann Jones, E. C.

2016-02-01

Rock coast research focuses largely on wave behaviour across beaches and shore platforms but rarely considers direct wave interaction with cliffs. Hydraulic action is one of the most important drivers of erosion along rock coasts. The magnitude of wave impact pressure has been shown by numerical and laboratory studies to be related to the wave shape. In deep water, a structure is only subjected to the hydrostatic pressure due to the oscillating clapotis. Dynamic pressures, related to the wave celerity, are exerted in shallower water when the wave is breaking at the point of impact; very high magnitude, short duration shock pressures are theorised to occur when the approaching wavefront is vertical. As such, wave shape may directly influence the potential of the impact to weaken rock and cause erosion. Measurements of impact pressure at coastal cliffs are limited, and the occurrence and influence of this phenomenon is currently poorly constrained. To address this, we have undertaken a field monitoring study on the magnitude and vertical distribution of wave impact pressures at the rocky, macro-tidal coastline of Staithes, North Yorkshire, UK. A series of piezo-resistive pressure transducers and a camera were installed at the base of the cliff during low tide. Transducers were deployed vertically up the cliff face and aligned shore-normal to capture the variation in static and dynamic pressure with height during a full spring tidal cycle. Five minute bursts of 5 kHz pressure readings and 4 Hz wave imaging were sampled every 30 minutes for six hours during high tide. Pressure measurements were then compensated for temperature and combined with wave imaging to produce a pressure time series and qualitative wave shape category for each wave impact. Results indicate the presence of a non-linear relationship between pressure impact magnitude, the occurrence of shock pressures, wave shape and tidal stage, and suggest that breaker type on impact (and controls thereof) may be fundamental in dictating the effectiveness of hydraulic action in eroding rock coast cliffs. Our findings demonstrate the sensitivity of wave loading to changes in water depth and, hence, projected sea-level rise. This research leads directly into a wider project investigating the role of wave shape as a key control on marine forcing of erosion.

Development Specification for RV-346/348 Positive Pressure Relief Valves (PPRV)

NASA Technical Reports Server (NTRS)

Ralston, Russell L.

2017-01-01

This specification establishes the requirements for design, performance, safety, testing, and manufacture of the RV-346 and RV-348, Positive Pressure Relief Valve (PPRV) as part of the Advanced Extravehicular Mobility Unit (EMU)(AEMU) Portable Life Support System (PLSS). The RV-346 serves as the Positive Pressure Relief Valve (PPRV), and the RV-348 serves as the Secondary Positive Pressure Relief Valve (SPPRV).

11. RW Meyer Sugar Mill: 18761889. Locomotive=type, firetube, portable boiler, ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

11. RW Meyer Sugar Mill: 1876-1889. Locomotive=type, fire-tube, portable boiler, model No. 1, Manufactured by Ames Iron Works, Oswego, New York, 1879. 120 lbs./sq. in. working pressure, 66 sq. ft. heating surface in tubes. View: the boiler provided steam for steam engine which in turn powered the centrifugals. View shows front fire box, end of boiler. Below fire-box,used for removing ashes, is a door. Circular openings at the rear of the fire-box are where fire-tubes connected with furnace. Column to right of fire-box carried pressure and water level gauges. Fluted chimney-type structure is steam-port, safety valve, and whistle. Weights originally sat on the arm extending from the top of the port and controlled the boiler pressure. - R. W. Meyer Sugar Mill, State Route 47, Kualapuu, Maui County, HI

Portable monitoring for the diagnosis of obstructive sleep apnea.

PubMed

Collop, Nancy A

2008-11-01

The demand for expedient diagnosis of suspected obstructive sleep apnea (OSA) has increased due to improved awareness of sleep disorders. Polysomnography (PSG) is the current preferred diagnostic modality but is relatively inconvenient, expensive and inefficient. Portable monitoring has been developed and is widely used in countries outside the United States as an alternative approach. A portable monitor records fewer physiologic variables but is typically unattended and can be performed in the home. Numerous portable monitor studies have been performed over the past two to three decades. The US government and medical societies have extensively reviewed this literature several times in an attempt to determine if portable monitoring should be more broadly used for diagnosing OSA. In March 2008, the US Centers for Medicare and Medicaid Services released a statement allowing the use of portable monitoring to diagnose OSA and prescribe continuous positive airway pressure. This has potentially opened the door for more widespread use of these devices. This review will focus on the literature that has examined portable monitoring as a diagnostic tool for OSA. It is anticipated that portable monitoring as a diagnostic modality for OSA will be used more frequently in the United States following the Centers for Medicare and Medicaid Services ruling. Physicians and others considering the use of portable monitors should thoroughly understand the advantages and limitations of this technology.

29 CFR 1910.157 - Portable fire extinguishers.

Code of Federal Regulations, 2012 CFR

2012-07-01

... extinguisher to rupture the cartridge or to initiate an uncontrollable pressure generating chemical reaction to... stored pressure dry chemical extinguishers that require a 12-year hydrostatic test are emptied and subjected to applicable maintenance procedures every 6 years. Dry chemical extinguishers having non...

29 CFR 1910.157 - Portable fire extinguishers.

Code of Federal Regulations, 2013 CFR

2013-07-01

... extinguisher to rupture the cartridge or to initiate an uncontrollable pressure generating chemical reaction to... stored pressure dry chemical extinguishers that require a 12-year hydrostatic test are emptied and subjected to applicable maintenance procedures every 6 years. Dry chemical extinguishers having non...

29 CFR 1910.157 - Portable fire extinguishers.

Code of Federal Regulations, 2014 CFR

2014-07-01

... extinguisher to rupture the cartridge or to initiate an uncontrollable pressure generating chemical reaction to... stored pressure dry chemical extinguishers that require a 12-year hydrostatic test are emptied and subjected to applicable maintenance procedures every 6 years. Dry chemical extinguishers having non...

29 CFR 1910.157 - Portable fire extinguishers.

Code of Federal Regulations, 2011 CFR

2011-07-01

... extinguisher to rupture the cartridge or to initiate an uncontrollable pressure generating chemical reaction to... stored pressure dry chemical extinguishers that require a 12-year hydrostatic test are emptied and subjected to applicable maintenance procedures every 6 years. Dry chemical extinguishers having non...

Measurement of the Length of Installed Rock Bolt Based on Stress Wave Reflection by Using a Giant Magnetostrictive (GMS) Actuator and a PZT Sensor.

PubMed

Luo, Mingzhang; Li, Weijie; Wang, Bo; Fu, Qingqing; Song, Gangbing

2017-02-23

Rock bolts, as a type of reinforcing element, are widely adopted in underground excavations and civil engineering structures. Given the importance of rock bolts, the research outlined in this paper attempts to develop a portable non-destructive evaluation method for assessing the length of installed rock bolts for inspection purposes. Traditionally, piezoelectric elements or hammer impacts were used to perform non-destructive evaluation of rock bolts. However, such methods suffered from many major issues, such as the weak energy generated and the requirement for permanent installation for piezoelectric elements, and the inconsistency of wave generation for hammer impact. In this paper, we proposed a portable device for the non-destructive evaluation of rock bolt conditions based on a giant magnetostrictive (GMS) actuator. The GMS actuator generates enough energy to ensure multiple reflections of the stress waves along the rock bolt and a lead zirconate titantate (PZT) sensor is used to detect the reflected waves. A new integrated procedure that involves correlation analysis, wavelet denoising, and Hilbert transform was proposed to process the multiple reflection signals to determine the length of an installed rock bolt. The experimental results from a lab test and field tests showed that, by analyzing the instant phase of the periodic reflections of the stress wave generated by the GMS transducer, the length of an embedded rock bolt can be accurately determined.

Measurement of the Length of Installed Rock Bolt Based on Stress Wave Reflection by Using a Giant Magnetostrictive (GMS) Actuator and a PZT Sensor

PubMed Central

Luo, Mingzhang; Li, Weijie; Wang, Bo; Fu, Qingqing; Song, Gangbing

2017-01-01

Rock bolts, as a type of reinforcing element, are widely adopted in underground excavations and civil engineering structures. Given the importance of rock bolts, the research outlined in this paper attempts to develop a portable non-destructive evaluation method for assessing the length of installed rock bolts for inspection purposes. Traditionally, piezoelectric elements or hammer impacts were used to perform non-destructive evaluation of rock bolts. However, such methods suffered from many major issues, such as the weak energy generated and the requirement for permanent installation for piezoelectric elements, and the inconsistency of wave generation for hammer impact. In this paper, we proposed a portable device for the non-destructive evaluation of rock bolt conditions based on a giant magnetostrictive (GMS) actuator. The GMS actuator generates enough energy to ensure multiple reflections of the stress waves along the rock bolt and a lead zirconate titantate (PZT) sensor is used to detect the reflected waves. A new integrated procedure that involves correlation analysis, wavelet denoising, and Hilbert transform was proposed to process the multiple reflection signals to determine the length of an installed rock bolt. The experimental results from a lab test and field tests showed that, by analyzing the instant phase of the periodic reflections of the stress wave generated by the GMS transducer, the length of an embedded rock bolt can be accurately determined. PMID:28241503

Predicting S-wave velocities for unconsolidated sediments at low effective pressure

USGS Publications Warehouse

Lee, Myung W.

2010-01-01

Accurate S-wave velocities for shallow sediments are important in performing a reliable elastic inversion for gas hydrate-bearing sediments and in evaluating velocity models for predicting S-wave velocities, but few S-wave velocities are measured at low effective pressure. Predicting S-wave velocities by using conventional methods based on the Biot-Gassmann theory appears to be inaccurate for laboratory-measured velocities at effective pressures less than about 4-5 megapascals (MPa). Measured laboratory and well log velocities show two distinct trends for S-wave velocities with respect to P-wave velocity: one for the S-wave velocity less than about 0.6 kilometer per second (km/s) which approximately corresponds to effective pressure of about 4-5 MPa, and the other for S-wave velocities greater than 0.6 km/s. To accurately predict S-wave velocities at low effective pressure less than about 4-5 MPa, a pressure-dependent parameter that relates the consolidation parameter to shear modulus of the sediments at low effective pressure is proposed. The proposed method in predicting S-wave velocity at low effective pressure worked well for velocities of water-saturated sands measured in the laboratory. However, this method underestimates the well-log S-wave velocities measured in the Gulf of Mexico, whereas the conventional method performs well for the well log velocities. The P-wave velocity dispersion due to fluid in the pore spaces, which is more pronounced at high frequency with low effective pressures less than about 4 MPa, is probably a cause for this discrepancy.

Miniaturized optical wavelength sensors

NASA Astrophysics Data System (ADS)

Kung, Helen Ling-Ning

Recently semiconductor processing technology has been applied to the miniaturization of optical wavelength sensors. Compact sensors enable new applications such as integrated diode-laser wavelength monitors and frequency lockers, portable chemical and biological detection, and portable and adaptive hyperspectral imaging arrays. Small sensing systems have trade-offs between resolution, operating range, throughput, multiplexing and complexity. We have developed a new wavelength sensing architecture that balances these parameters for applications involving hyperspectral imaging spectrometer arrays. In this thesis we discuss and demonstrate two new wavelength-sensing architectures whose single-pixel designs can easily be extended into spectrometer arrays. The first class of devices is based on sampling a standing wave. These devices are based on measuring the wavelength-dependent period of optical standing waves formed by the interference of forward and reflected waves at a mirror. We fabricated two different devices based on this principle. The first device is a wavelength monitor, which measures the wavelength and power of a monochromatic source. The second device is a spectrometer that can also act as a selective spectral coherence sensor. The spectrometer contains a large displacement piston-motion MEMS mirror and a thin GaAs photodiode flip-chip bonded to a quartz substrate. The performance of this spectrometer is similar to that of a Michelson in resolution, operating range, throughput and multiplexing but with the added advantages of fewer components and one-dimensional architecture. The second class of devices is based on the Talbot self-imaging effect. The Talbot effect occurs when a periodic object is illuminated with a spatially coherent wave. Periodically spaced self-images are formed behind the object. The spacing of the self-images is proportional to wavelength of the incident light. We discuss and demonstrate how this effect can be used for spectroscopy. In the conclusion we compare these two new miniaturized spectrometer architectures to existing miniaturized spectrometers. We believe that the combination of miniaturized wavelength sensors and smart processing should facilitate the development real-time, adaptive and portable sensing systems.

Note: A portable, light-emitting diode-based ruby fluorescence spectrometer for high-pressure calibration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feng Yejun

2011-04-15

Ruby (Al{sub 2}O{sub 3}, with {approx}0.5 wt. % Cr doping) is one of the most widely used manometers at the giga-Pascal scale. Traditionally, its fluorescence is excited with intense laser sources. Here, I present a simple, robust, and portable design that employs light-emitting diodes (LEDs) instead. This LED-based system is safer in comparison with laser-based ones.

Investigation of scaling characteristics for defining design environments due to transient ground winds and near-field, nonlinear acoustic fields

NASA Technical Reports Server (NTRS)

Shih, C. C.

1973-01-01

In order to establish a foundation of scaling laws for the highly nonlinear waves associated with the launch vehicle, the basic knowledge of the relationships among the paramaters pertinent to the energy dissipation process associated with the propagation of nonlinear pressure waves in thermoviscous media is required. The problem of interest is to experimentally investigate the temporal and spacial velocity profiles of fluid flow in a 3-inch open-end pipe of various lengths, produced by the propagation of nonlinear pressure waves for various diaphragm burst pressures of a pressure wave generator. As a result, temporal and spacial characteristics of wave propagation for a parametric set of nonlinear pressure waves in the pipe containing air under atmospheric conditions were determined. Velocity measurements at five sections along the pipes of up to 210 ft. in length were made with hot-film anemometers for five pressure waves produced by a piston. The piston was derived with diaphragm burst pressures at 20, 40, 60, 80 and 100 psi in the driver chamber of the pressure wave generator.

Relevance of a Managerial Decision-Model to Educational Administration.

ERIC Educational Resources Information Center

Lundin, Edward.; Welty, Gordon

The rational model of classical economic theory assumes that the decision maker has complete information on alternatives and consequences, and that he chooses the alternative that maximizes expected utility. This model does not allow for constraints placed on the decision maker resulting from lack of information, organizational pressures,…

Pulmonary artery wave propagation and reservoir function in conscious man: impact of pulmonary vascular disease, respiration and dynamic stress tests.

PubMed

Su, Junjing; Manisty, Charlotte; Simonsen, Ulf; Howard, Luke S; Parker, Kim H; Hughes, Alun D

2017-10-15

Wave travel plays an important role in cardiovascular physiology. However, many aspects of pulmonary arterial wave behaviour remain unclear. Wave intensity and reservoir-excess pressure analyses were applied in the pulmonary artery in subjects with and without pulmonary hypertension during spontaneous respiration and dynamic stress tests. Arterial wave energy decreased during expiration and Valsalva manoeuvre due to decreased ventricular preload. Wave energy also decreased during handgrip exercise due to increased heart rate. In pulmonary hypertension patients, the asymptotic pressure at which the microvascular flow ceases, the reservoir pressure related to arterial compliance and the excess pressure caused by waves increased. The reservoir and excess pressures decreased during Valsalva manoeuvre but remained unchanged during handgrip exercise. This study provides insights into the influence of pulmonary vascular disease, spontaneous respiration and dynamic stress tests on pulmonary artery wave propagation and reservoir function. Detailed haemodynamic analysis may provide novel insights into the pulmonary circulation. Therefore, wave intensity and reservoir-excess pressure analyses were applied in the pulmonary artery to characterize changes in wave propagation and reservoir function during spontaneous respiration and dynamic stress tests. Right heart catheterization was performed using a pressure and Doppler flow sensor tipped guidewire to obtain simultaneous pressure and flow velocity measurements in the pulmonary artery in control subjects and patients with pulmonary arterial hypertension (PAH) at rest. In controls, recordings were also obtained during Valsalva manoeuvre and handgrip exercise. The asymptotic pressure at which the flow through the microcirculation ceases, the reservoir pressure related to arterial compliance and the excess pressure caused by arterial waves increased in PAH patients compared to controls. The systolic and diastolic rate constants also increased, while the diastolic time constant decreased. The forward compression wave energy decreased by ∼8% in controls and ∼6% in PAH patients during expiration compared to inspiration, while the wave speed remained unchanged throughout the respiratory cycle. Wave energy decreased during Valsalva manoeuvre (by ∼45%) and handgrip exercise (by ∼27%) with unaffected wave speed. Moreover, the reservoir and excess pressures decreased during Valsalva manoeuvre but remained unaltered during handgrip exercise. In conclusion, reservoir-excess pressure analysis applied to the pulmonary artery revealed distinctive differences between controls and PAH patients. Variations in the ventricular preload and afterload influence pulmonary arterial wave propagation as demonstrated by changes in wave energy during spontaneous respiration and dynamic stress tests. © 2017 The Authors. The Journal of Physiology © 2017 The Physiological Society.

Modified ACES Portable Life Support Integration, Design, and Testing for Exploration Missions

NASA Technical Reports Server (NTRS)

Kelly, Cody

2014-01-01

NASA's next generation of exploration missions provide a unique challenge to designers of EVA life support equipment, especially in a fiscally-constrained environment. In order to take the next steps of manned space exploration, NASA is currently evaluating the use of the Modified ACES (MACES) suit in conjunction with the Advanced Portable Life Support System (PLSS) currently under development. This paper will detail the analysis and integration of the PLSS thermal and ventilation subsystems into the MACES pressure garment, design of prototype hardware, and hardware-in-the-loop testing during the spring 2014 timeframe. Prototype hardware was designed with a minimal impact philosophy in order to mitigate design constraints becoming levied on either the advanced PLSS or MACES subsystems. Among challenges faced by engineers were incorporation of life support thermal water systems into the pressure garment cavity, operational concept definition between vehicle/portable life support system hardware, and structural attachment mechanisms while still enabling maximum EVA efficiency from a crew member's perspective. Analysis was completed in late summer 2013 to 'bound' hardware development, with iterative analysis cycles throughout the hardware development process. The design effort will cumulate in the first ever manned integration of NASA's advanced PLSS system with a pressure garment originally intended primarily for use in a contingency survival scenario.

Portable fiber optic coupled Doppler interferometer system for detonation and shock wave diagnostics

NASA Technical Reports Server (NTRS)

Fleming, Kevin J.

1993-01-01

Testing and analysis of shock wave characteristics such as detonators and ground shock propagation frequently require a method of measuring velocity and displacement of the surface of interest. One method of measurement is Doppler interferometry. The VISAR (Velocity Interferometer System for Any Reflector) uses Doppler interferometry and has gained wide acceptance as the preferred tool for shock measurement. An important asset of VISAR is that it measures velocity and displacement nonintrusively.

Acceptance test report for portable exhauster POR-007/Skid E

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kriskovich, J.R.

1998-07-24

This document describes Acceptance Testing performed on Portable Exhauster POR-007/Skid E. It includes measurements of bearing vibration levels, pressure decay testing, programmable logic controller interlocks, high vacuum, flow and pressure control functional testing. The purpose of Acceptance testing documented by this report was to demonstrate compliance of the exhausters with the performance criteria established within HNF-0490, Rev. 1 following a repair and upgrade effort at Hanford. In addition, data obtained during this testing is required for the resolution of outstanding Non-conformance Reports (NCR), and finally, to demonstrate the functionality of the associated software for the pressure control and high vacuummore » exhauster operating modes provided for by W-320. Additional testing not required by the ATP was also performed to assist in the disposition and close out of receiving inspection report and for application design information (system curve). Results of this testing are also captured within this document.« less

Seismogram offers insight into Oklahoma City bombing

NASA Astrophysics Data System (ADS)

Holzer, Thomas L.; Fletcher, Joe B.; Fuis, Gary S.; Ryberg, Trond; Brocher, Thomas M.; Dietel, Christopher M.

The terrorist bombing of the Alfred P. Murrah Federal Building in Oklahoma City on April 19, 1995, generated seismic waves that were recorded on two permanent seismographs about 7 and 26 km away from the bombing. The seismogram recorded at 26 km shows two low-frequency wave trains, discrete sets of oscillatory signals, that begin about 10 s apart. Public release of this record prompted speculation that each wave train was caused by a different energy source. On May 23, 1995, the U.S. Geological Survey monitored the demolition of the bomb-ravaged Federal Building with portable seismographs (Figure 1). Two wave trains were picked up again. The recordings indicate that the wave trains during both the bombing and demolition represent seismic waves traveling at different velocities. We conclude that the two wave trains recorded during the bombing are consistent with a single impulsive energy source.

Laboratory study of spectral waves over a muddy bottom

NASA Astrophysics Data System (ADS)

Maxeiner, E.; Dalrymple, R. A.

2010-12-01

The attenuation of water waves propagating over a muddy ocean floor has been studied extensively both analytically and experimentally over the past 30 years. Possible mechanisms for this include surface wave interactions with the bottom, surface wave interactions with waves formed at the water/mud interface (lutocline) and shear instability at the water/mud interface. Typically these studies have focused on monochromatic waves. Observations of wave attenuation in the field, however, are subject to a spectrum of wave frequencies and sizes. A few field studies (Sheremet and Stone, 2003; Elgar and Raubenheimer, 2008) have explored the possible effects that a wide spectrum of wave frequencies may have on wave damping mechanisms. In this study, the wave attenuation exhibited by a sea spectrum over a muddy bottom is studied experimentally in a laboratory for the first time. Using an 18 m-long wave tank at the Coastal Engineering Laboratory at Johns Hopkins University, a piston-style wave maker is used to create both monochromatic and spectral waves. A 10 m-long section of the tank floor incorporates a recessed layer of kaolinite clay which subsequently mixes with the overlying water in the presence of waves. Testing consists of three phases. First, a series of monochromatic wave trains are produced over a range of wave frequencies and in a range of water depths to assess the damping behavior with respect to a variety of parameters such as wave frequency, wave height and water depth. Damping is assessed by comparing wave height at various longitudinal locations in the tank. Second, “wave beats” are created by superimposing waves of two frequencies to create a longer envelope. Third, the wave maker is used to generate a representative random sea condition, based on the Pierson-Moskowitz sea spectrum. For this type of testing, damping is assessed by measuring wave energy flux over a period of time at various longitudinal locations in the tank. Spectral analysis is also performed at these locations to track changing spectral energy, as previous studies have hypothesized mechanisms of energy transfer between waves of different frequencies. This study is part of a Multidisciplinary University Research Initiative (MURI), which includes on computational, laboratory and field studies of wave damping in nearshore areas of the Gulf of Mexico along the coast of Louisiana.

49 CFR 178.275 - Specification for UN Portable Tanks intended for the transportation of liquid and solid hazardous...

Code of Federal Regulations, 2012 CFR

2012-10-01

... external heat. Fusible elements must not be utilized on portable tanks with a test pressure which exceeds 2... conductance of the insulation, in kW m −2 K −1, at 38 °C (100 °F); and t = actual temperature of the hazardous... given in this paragraph (i)(2)(i)(A) for insulated shells may only be used if the insulation is in...

49 CFR 178.275 - Specification for UN Portable Tanks intended for the transportation of liquid and solid hazardous...

Code of Federal Regulations, 2014 CFR

2014-10-01

... external heat. Fusible elements must not be utilized on portable tanks with a test pressure which exceeds 2... conductance of the insulation, in kW m −2 K −1, at 38 °C (100 °F); and t = actual temperature of the hazardous... given in this paragraph (i)(2)(i)(A) for insulated shells may only be used if the insulation is in...

49 CFR 178.275 - Specification for UN Portable Tanks intended for the transportation of liquid and solid hazardous...

Code of Federal Regulations, 2013 CFR

2013-10-01

... external heat. Fusible elements must not be utilized on portable tanks with a test pressure which exceeds 2... conductance of the insulation, in kW m −2 K −1, at 38 °C (100 °F); and t = actual temperature of the hazardous... given in this paragraph (i)(2)(i)(A) for insulated shells may only be used if the insulation is in...

49 CFR 178.275 - Specification for UN Portable Tanks intended for the transportation of liquid and solid hazardous...

Code of Federal Regulations, 2011 CFR

2011-10-01

... external heat. Fusible elements must not be utilized on portable tanks with a test pressure which exceeds 2... conductance of the insulation, in kW m −2 K −1, at 38 °C (100 °F); and t = actual temperature of the hazardous... given in this paragraph (i)(2)(i)(A) for insulated shells may only be used if the insulation is in...

49 CFR 178.275 - Specification for UN Portable Tanks intended for the transportation of liquid and solid hazardous...

Code of Federal Regulations, 2010 CFR

2010-10-01

... external heat. Fusible elements must not be utilized on portable tanks with a test pressure which exceeds 2... conductance of the insulation, in kW m −2 K −1, at 38 °C (100 °F); and t = actual temperature of the hazardous... given in this paragraph (i)(2)(i)(A) for insulated shells may only be used if the insulation is in...

Use of a Portable Stimulator to Treat GWI

DTIC Science & Technology

2016-10-01

equilibrium in veterans during stochastic noise electrical stim. Electrical Stimulation Time (sec) 0 5 10 15 20 m A -1.0 -0.5 0.0 0.5 1.0 Center of Pressure...AD______________ AWARD NUMBER: W81XWH-14-1-0598 TITLE: Use of a Portable Stimulator to Treat GWI PRINCIPAL INVESTIGATOR: Jorge M... time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this

Prompt Disappearance and Emergence of Radiation Belt Magnetosonic Waves Induced by Solar Wind Dynamic Pressure Variations

NASA Astrophysics Data System (ADS)

Liu, Nigang; Su, Zhenpeng; Zheng, Huinan; Wang, Yuming; Wang, Shui

2018-01-01

Magnetosonic waves are highly oblique whistler mode emissions transferring energy from the ring current protons to the radiation belt electrons in the inner magnetosphere. Here we present the first report of prompt disappearance and emergence of magnetosonic waves induced by the solar wind dynamic pressure variations. The solar wind dynamic pressure reduction caused the magnetosphere expansion, adiabatically decelerated the ring current protons for the Bernstein mode instability, and produced the prompt disappearance of magnetosonic waves. On the contrary, because of the adiabatic acceleration of the ring current protons by the solar wind dynamic pressure enhancement, magnetosonic waves emerged suddenly. In the absence of impulsive injections of hot protons, magnetosonic waves were observable even only during the time period with the enhanced solar wind dynamic pressure. Our results demonstrate that the solar wind dynamic pressure is an essential parameter for modeling of magnetosonic waves and their effect on the radiation belt electrons.

Diffraction of a plane wave by a three-dimensional corner

NASA Technical Reports Server (NTRS)

Ting, L.; Kung, F.

1971-01-01

By the superposition of the conical solution for the diffraction of a plane pulse by a three dimensional corner, the solution for a general incident plane wave is constructed. A numerical program is presented for the computation of the pressure distribution on the surface due to an incident plane wave of any wave form and at any incident angle. Numerical examples are presented to show the pressure signature at several points on the surface due to incident wave with a front shock wave, two shock waves in succession, or a compression wave with same peak pressure. The examples show that when the distance of a point on the surface from the edges or the vertex is comparable to the distance for the front pressure raise to reach the maximum, the peak pressure at that point can be much less than that given by a regular reflection, because the diffracted wave front arrives at that point prior to the arrival of the peak incident wave.

Does Migration Limit the Effect of Health Insurance on Hypertension Management in China?

PubMed

Fang, Hai; Jin, Yinzi; Zhao, Miaomiao; Zhang, Huyang; A Rizzo, John; Zhang, Donglan; Hou, Zhiyuan

2017-10-20

Background: In China, rapid urbanization has caused migration from rural to urban areas, and raised the prevalence of hypertension. However, public health insurance is not portable from one place to another, and migration may limit the effectiveness of this non-portable health insurance on healthcare. Our study aims to investigate whether migration limits the effectiveness of health insurance on hypertension management in China. Methods: Data were obtained from the national baseline survey of the China Health and Retirement Longitudinal Study in 2011, including 4926 hypertensive respondents with public health insurance. Outcome measures included use of primary care, hypertension awareness, medication use, blood pressure monitoring, physician advice, and blood pressure control. Multivariate logistic regressions were estimated to examine whether the effects of rural health insurance on hypertension management differed between those who migrated to urban areas and those who did not migrate and lived in rural areas. Results: Among hypertensive respondents, 60.7% were aware of their hypertensive status. Compared to rural residents, the non-portable feature of rural health insurance significantly reduced rural-to-urban migrants' probabilities of using primary care by 7.8 percentage points, hypertension awareness by 8.8 percentage points, and receiving physician advice by 18.3 percentage points. Conclusions: In China, migration to urban areas limited the effectiveness of rural health insurance on hypertension management due to its non-portable nature. It is critical to improve the portability of rural health insurance, and to extend urban health insurance and primary care coverage to rural-to-urban migrants to achieve better chronic disease management.

Does Migration Limit the Effect of Health Insurance on Hypertension Management in China?

PubMed Central

Fang, Hai; Jin, Yinzi; Zhang, Huyang; A. Rizzo, John; Zhang, Donglan; Hou, Zhiyuan

2017-01-01

Background: In China, rapid urbanization has caused migration from rural to urban areas, and raised the prevalence of hypertension. However, public health insurance is not portable from one place to another, and migration may limit the effectiveness of this non-portable health insurance on healthcare. Our study aims to investigate whether migration limits the effectiveness of health insurance on hypertension management in China. Methods: Data were obtained from the national baseline survey of the China Health and Retirement Longitudinal Study in 2011, including 4926 hypertensive respondents with public health insurance. Outcome measures included use of primary care, hypertension awareness, medication use, blood pressure monitoring, physician advice, and blood pressure control. Multivariate logistic regressions were estimated to examine whether the effects of rural health insurance on hypertension management differed between those who migrated to urban areas and those who did not migrate and lived in rural areas. Results: Among hypertensive respondents, 60.7% were aware of their hypertensive status. Compared to rural residents, the non-portable feature of rural health insurance significantly reduced rural-to-urban migrants’ probabilities of using primary care by 7.8 percentage points, hypertension awareness by 8.8 percentage points, and receiving physician advice by 18.3 percentage points. Conclusions: In China, migration to urban areas limited the effectiveness of rural health insurance on hypertension management due to its non-portable nature. It is critical to improve the portability of rural health insurance, and to extend urban health insurance and primary care coverage to rural-to-urban migrants to achieve better chronic disease management. PMID:29053607

Wave reflections in the pulmonary arteries analysed with the reservoir–wave model

PubMed Central

Bouwmeester, J Christopher; Belenkie, Israel; Shrive, Nigel G; Tyberg, John V

2014-01-01

Conventional haemodynamic analysis of pressure and flow in the pulmonary circulation yields incident and reflected waves throughout the cardiac cycle, even during diastole. The reservoir–wave model provides an alternative haemodynamic analysis consistent with minimal wave activity during diastole. Pressure and flow in the main pulmonary artery were measured in anaesthetized dogs and the effects of hypoxia and nitric oxide, volume loading and positive end-expiratory pressure were observed. The reservoir–wave model was used to determine the reservoir contribution to pressure and flow and once subtracted, resulted in ‘excess’ quantities, which were treated as wave-related. Wave intensity analysis quantified the contributions of waves originating upstream (forward-going waves) and downstream (backward-going waves). In the pulmonary artery, negative reflections of incident waves created by the right ventricle were observed. Overall, the distance from the pulmonary artery valve to this reflection site was calculated to be 5.7 ± 0.2 cm. During 100% O2 ventilation, the strength of these reflections increased 10% with volume loading and decreased 4% with 10 cmH2O positive end-expiratory pressure. In the pulmonary arterial circulation, negative reflections arise from the junction of lobar arteries from the left and right pulmonary arteries. This mechanism serves to reduce peak systolic pressure, while increasing blood flow. PMID:24756638

Acute effects of ultrafiltration on aortic mechanical properties determined by measurement of pulse wave velocity and pulse propagation time in hemodialysis patients

PubMed Central

Yıldız, Banu Şahin; Şahin, Alparslan; Aladağ, Nazire Başkurt; Arslan, Gülgün; Kaptanoğulları, Hakan; Akın, İbrahim; Yıldız, Mustafa

2015-01-01

Objective: The effects of acute hemodialysis session on pulse wave velocity are conflicting. The aim of the current study was to assess the acute effects of ultrafiltration on the aortic mechanical properties using carotid-femoral (aortic) pulse wave velocity and pulse propagation time. Methods: A total of 26 (12 women, 14 men) consecutive patients on maintenance hemodialysis (mean dialysis duration: 40.7±25.6 (4-70) months) and 29 healthy subjects (13 women, 16 men) were included in this study. Baseline blood pressure, carotid-femoral (aortic) pulse wave velocity, and pulse propagation time were measured using a Complior Colson device (Createch Industrie, France) before and immediately after the end of the dialysis session. Results: While systolic blood pressure, diastolic blood pressure, mean blood pressure, pulse pressure, and pulse wave velocity were significantly higher in patients on hemodialysis than in healthy subjects, pulse propagation time was significantly higher in healthy subjects. Although body weight, systolic blood pressure, diastolic blood pressure, mean blood pressure, pulse pressure, and pulse wave velocity were significantly decreased, heart rate and pulse propagation time were significantly increased after ultrafiltration. There was a significant positive correlation between pulse wave velocity and age, body height, waist circumference, systolic blood pressure, diastolic blood pressure, mean blood pressure, pulse pressure, and heart rate. Conclusion: Although hemodialysis treatment may chronically worsen aortic mechanical properties, ultrafiltration during hemodialysis may significantly improve aortic pulse wave velocity, which is inversely related to aortic distensibility and pulse propagation time. PMID:25413228

Acoustically and Electrokinetically Driven Transport in Microfluidic Devices

NASA Astrophysics Data System (ADS)

Sayar, Ersin

Electrokinetically driven flows are widely employed as a primary method for liquid pumping in micro-electromechanical systems. Mixing of analytes and reagents is limited in microfluidic devices due to the low Reynolds number of the flows. Acoustic excitations have recently been suggested to promote mixing in the microscale flow systems. Electrokinetic flows through straight microchannels were investigated using the Poisson-Boltzmann and Nernst-Planck models. The acoustic wave/fluid flow interactions in a microchannel were investigated via the development of two and three-dimensional dynamic predictive models for flows with field couplings of the electrical, mechanical and fluid flow quantities. The effectiveness and applicability of electrokinetic augmentation in flexural plate wave micropumps for enhanced capabilities were explored. The proposed concept can be exploited to integrate micropumps into complex microfluidic chips improving the portability of micro-total-analysis systems along with the capabilities of actively controlling acoustics and electrokinetics for micro-mixer applications. Acoustically excited flows in microchannels consisting of flexural plate wave devices and thin film resonators were considered. Compressible flow fields were considered to accommodate the acoustic excitations produced by a vibrating wall. The velocity and pressure profiles for different parameters including frequency, channel height, wave amplitude and length were investigated. Coupled electrokinetics and acoustics cases were investigated while the electric field intensity of the electrokinetic body forces and actuation frequency of acoustic excitations were varied. Multifield analysis of a piezoelectrically actuated valveless micropump was also presented. The effect of voltage and frequency on membrane deflection and flow rate were investigated. Detailed fluid/solid deformation coupled simulations of piezoelectric valveless micropump have been conducted to predict the generated time averaged flow rates. Developed coupled solid and fluid mechanics models can be utilized to integrate flow-through sensors with microfluidic chips.

Plateau Waves of Intracranial Pressure and Multimodal Brain Monitoring.

PubMed

Dias, Celeste; Maia, Isabel; Cerejo, Antonio; Smielewski, Peter; Paiva, José-Artur; Czosnyka, Marek

2016-01-01

The aim of this study was to describe multimodal brain monitoring characteristics during plateau waves of intracranial pressure (ICP) in patients with head injury, using ICM+ software for continuous recording. Plateau waves consist of an abrupt elevation of ICP above 40 mmHg for 5-20 min. This is a prospective observational study of patients with head injury who were admitted to a neurocritical care unit and who developed plateau waves. We analyzed 59 plateau waves that occurred in 8 of 18 patients (44 %). At the top of plateau waves arterial blood pressure remained almost constant, but cerebral perfusion pressure, cerebral blood flow, brain tissue oxygenation, and cerebral oximetry decreased. After plateau waves, patients with a previously better autoregulation status developed hyperemia, demonstrated by an increase in cerebral blood flow and brain oxygenation. Pressure and oxygen cerebrovascular reactivity indexes (pressure reactivity index and ORxshort) increased significantly during the plateau wave as a sign of disruption of autoregulation. Bedside multimodal brain monitoring is important to characterize increases in ICP and give differential diagnoses of plateau waves, as management of this phenomenon differs from that of regular ICP.

Portable evanescent wave fiber biosensor for highly sensitive detection of Shigella

NASA Astrophysics Data System (ADS)

Xiao, Rui; Rong, Zhen; Long, Feng; Liu, Qiqi

2014-11-01

A portable evanescent wave fiber biosensor was developed to achieve the rapid and highly sensitive detection of Shigella. In this study, a DNA probe was covalently immobilized onto fiber-optic biosensors that can hybridize with a fluorescently labeled complementary DNA. The sensitivity of detection for synthesized oligonucleotides can reach 10-10 M. The surface of the sensor can be regenerated with 0.5% sodium dodecyl sulfate solution (pH 1.9) for over 30 times without significant deterioration of performance. The total analysis time for a single sample, including the time for measurement and surface regeneration, was less than 6 min. We employed real-time polymerase chain reaction (PCR) and compared the results of both methods to investigate the actual Shigella DNA detection capability of the fiber-optic biosensor. The fiber-optic biosensor could detect as low as 102 colony-forming unit/mL Shigella. This finding was comparable with that by real-time PCR, which suggests that this method is a potential alternative to existing detection methods.

Investigations of High Pressure Acoustic Waves in Resonators with Seal-Like Features

NASA Technical Reports Server (NTRS)

Daniels, Christopher C.; Steinetz, Bruce M.; Finkbeiner, Joshua R.; Li, Xiao-Fan; Raman, Ganesh

2004-01-01

1) Standing waves with maximum pressures of 188 kPa have been produced in resonators containing ambient pressure air; 2) Addition of structures inside the resonator shifts the fundamental frequency and decreases the amplitude of the generated pressure waves; 3) Addition of holes to the resonator does reduce the magnitude of the acoustic waves produced, but their addition does not prohibit the generation of large magnitude non-linear standing waves; 4) The feasibility of reducing leakage using non-linear acoustics has been confirmed.

NASA Tech Briefs, October 2012

NASA Technical Reports Server (NTRS)

2012-01-01

Topics discussed include: Detection of Chemical Precursors of Explosives; Detecting Methane From Leaking Pipelines and as Greenhouse Gas in the Atmosphere; Onboard Sensor Data Qualification in Human-Rated Launch Vehicles; Rugged, Portable, Real-Time Optical Gaseous Analyzer for Hydrogen Fluoride; A Probabilistic Mass Estimation Algorithm for a Novel 7-Channel Capacitive Sample Verification Sensor; Low-Power Architecture for an Optical Life Gas Analyzer; Online Cable Tester and Rerouter; A Three-Frequency Feed for Millimeter-Wave Radiometry; Capacitance Probe Resonator for Multichannel Electrometer; Inverted Three-Junction Tandem Thermophotovoltaic Modules; Fabrication of Single Crystal MgO Capsules; Inflatable Hangar for Assembly of Large Structures in Space; Mars Aqueous Processing System; Hybrid Filter Membrane; Design for the Structure and the Mechanics of Moballs; Pressure Dome for High-Pressure Electrolyzer; Cascading Tesla Oscillating Flow Diode for Stirling Engine Gas Bearings; Compact, Low-Force, Low-Noise Linear Actuator; Ultra-Compact Motor Controller; Extreme Ionizing-Radiation-Resistant Bacterium; Wideband Single-Crystal Transducer for Bone Characterization; Fluorescence-Activated Cell Sorting of Live Versus Dead Bacterial Cells and Spores; Nonhazardous Urine Pretreatment Method; Laser-Ranging Transponders for Science Investigations of the Moon and Mars; Ka-Band Waveguide Three-Way Serial Combiner for MMIC Amplifiers; Structural Health Monitoring with Fiber Bragg Grating and Piezo Arrays; Low-Gain Circularly Polarized Antenna with Torus-Shaped Pattern; Stereo and IMU- Assisted Visual Odometry for Small Robots; Global Swath and Gridded Data Tiling; GOES-R: Satellite Insight; Aquarius iPhone Application; Monitoring of International Space Station Telemetry Using Shewhart Control Charts; Theory of a Traveling Wave Feed for a Planar Slot Array Antenna; Time Manager Software for a Flight Processor; Simulation of Oxygen Disintegration and Mixing With Hydrogen or Helium at Supercritical Pressure; A Superfluid Pulse Tube Refrigerator Without Moving Parts for Sub-Kelvin Cooling; Sapphire Viewports for a Venus Probe; The Mobile Chamber; Electric Propulsion Induced Secondary Mass Spectroscopy; and Radiation-Tolerant DC-DC Converters.

Engineering studies of vectorcardiographs in blood pressure measuring systems, appendix 2

NASA Technical Reports Server (NTRS)

Mark, R. G.

1975-01-01

The development of a cardiovascular monitoring system to noninvasively monitor the blood pressure and heart rate using pulse wave velocity was described. The following topics were covered: (1) pulse wave velocity as a measure of arterial blood pressure, (2) diastolic blood pressure and pulse wave velocity in humans, (3) transducer development for blood pressure measuring device, and (4) cardiovascular monitoring system. It was found, in experiments on dogs, that the pulse wave velocity is linearly related to diastolic blood pressure over a wide range of blood pressure and in the presence of many physiological perturbations. A similar relationship was observed in normal, young human males over a moderate range of pressures. Past methods for monitoring blood pressure and a new method based on pulse wave velocity determination were described. Two systems were tested: a Doppler ultrasonic transducer and a photoelectric plethysmograph. A cardiovascular monitoring system was described, including operating instructions.

R&D 100 Winner 2010: Acoustic Wave Biosensors

ScienceCinema

Larson, Richard; Branch, Darren; Edwards, Thayne

2018-01-16

The acoustic wave biosensor is innovative device that is a handheld, battery-powered, portable detection system capable of multiplex identification of a wide range of medically relevant pathogens and their biomolecular signatures — viruses, bacteria, proteins, and DNA — at clinically relevant levels. This detection occurs within minutes — not hours — at the point of care, whether that care is in a physician's office, a hospital bed, or at the scene of a biodefense or biomedical emergency.

TECHNICAL NOTE: Portable audio electronics for impedance-based measurements in microfluidics

NASA Astrophysics Data System (ADS)

Wood, Paul; Sinton, David

2010-08-01

We demonstrate the use of audio electronics-based signals to perform on-chip electrochemical measurements. Cell phones and portable music players are examples of consumer electronics that are easily operated and are ubiquitous worldwide. Audio output (play) and input (record) signals are voltage based and contain frequency and amplitude information. A cell phone, laptop soundcard and two compact audio players are compared with respect to frequency response; the laptop soundcard provides the most uniform frequency response, while the cell phone performance is found to be insufficient. The audio signals in the common portable music players and laptop soundcard operate in the range of 20 Hz to 20 kHz and are found to be applicable, as voltage input and output signals, to impedance-based electrochemical measurements in microfluidic systems. Validated impedance-based measurements of concentration (0.1-50 mM), flow rate (2-120 µL min-1) and particle detection (32 µm diameter) are demonstrated. The prevailing, lossless, wave audio file format is found to be suitable for data transmission to and from external sources, such as a centralized lab, and the cost of all hardware (in addition to audio devices) is ~10 USD. The utility demonstrated here, in combination with the ubiquitous nature of portable audio electronics, presents new opportunities for impedance-based measurements in portable microfluidic systems.

Cloud-point detection using a portable thickness shear mode crystal resonator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mansure, A.J.; Spates, J.J.; Germer, J.W.

1997-08-01

The Thickness Shear Mode (TSM) crystal resonator monitors the crude oil by propagating a shear wave into the oil. The coupling of the shear wave and the crystal vibrations is a function of the viscosity of the oil. By driving the crystal with circuitry that incorporates feedback, it is possible to determine the change from Newtonian to non-Newtonian viscosity at the cloud point. A portable prototype TSM Cloud Point Detector (CPD) has performed flawlessly during field and lab tests proving the technique is less subjective or operator dependent than the ASTM standard. The TSM CPD, in contrast to standard viscositymore » techniques, makes the measurement in a closed container capable of maintaining up to 100 psi. The closed container minimizes losses of low molecular weight volatiles, allowing samples (25 ml) to be retested with the addition of chemicals. By cycling/thermal soaking the sample, the effects of thermal history can be investigated and eliminated as a source of confusion. The CPD is portable, suitable for shipping the field offices for use by personnel without special training or experience in cloud point measurements. As such, it can make cloud point data available without the delays and inconvenience of sending samples to special labs. The crystal resonator technology can be adapted to in-line monitoring of cloud point and deposition detection.« less

Demonstration of a portable near-infrared CH4 detection sensor based on tunable diode laser absorption spectroscopy

NASA Astrophysics Data System (ADS)

Zheng, Chuan-Tao; Huang, Jian-Qiang; Ye, Wei-Lin; Lv, Mo; Dang, Jing-Min; Cao, Tian-Shu; Chen, Chen; Wang, Yi-Ding

2013-11-01

A portable near-infrared (NIR) CH4 detection sensor based on a distributed feedback (DFB) laser modulated at 1.654 μm is experimentally demonstrated. Intelligent temperature controller with an accuracy of -0.07 to +0.09 °C as well as a scan and modulation module generating saw-wave and cosine-wave signals are developed to drive the DFB laser, and a cost effective lock-in amplifier used to extract the second harmonic signal is integrated. Thorough experiments are carried out to obtain detection performances, including detection range, accuracy, stability and the minimum detection limit (MDL). Measurement results show that the absolute detection error relative to the standard value is less than 7% within the range of 0-100%, and the MDL is estimated to be about 11 ppm under an absorption length of 0.2 m and a noise level of 2 mVpp. Twenty-four hours monitoring on two gas samples (0.1% and 20%) indicates that the absolute errors are less than 7% and 2.5%, respectively, suggesting good long term stability. The sensor reveals competitive characteristics compared with other reported portable or handheld sensors. The developed sensor can also be used for the detection of other gases by adopting other DFB lasers with different center-wavelength using the same hardware and slightly modified software.

The aortic reservoir-wave as a paradigm for arterial haemodynamics: insights from three-dimensional fluid-structure interaction simulations in a model of aortic coarctation.

PubMed

Segers, Patrick; Taelman, Liesbeth; Degroote, Joris; Bols, Joris; Vierendeels, Jan

2015-03-01

The reservoir-wave paradigm considers aortic pressure as the superposition of a 'reservoir pressure', directly related to changes in reservoir volume, and an 'excess' component ascribed to wave dynamics. The change in reservoir pressure is assumed to be proportional to the difference between aortic inflow and outflow (i.e. aortic volume changes), an assumption that is virtually impossible to validate in vivo. The aim of this study is therefore to apply the reservoir-wave paradigm to aortic pressure and flow waves obtained from three-dimensional fluid-structure interaction simulations in a model of a normal aorta, aortic coarctation (narrowed descending aorta) and stented coarctation (stiff segment in descending aorta). We found no unequivocal relation between the intraaortic volume and the reservoir pressure for any of the simulated cases. When plotted in a pressure-volume diagram, hysteresis loops are found that are looped in a clockwise way indicating that the reservoir pressure is lower than the pressure associated with the change in volume. The reservoir-wave analysis leads to very high excess pressures, especially for the coarctation models, but to surprisingly little changes of the reservoir component despite the impediment of the buffer capacity of the aorta. With the observation that reservoir pressure is not related to the volume in the aortic reservoir in systole, an intrinsic assumption in the wave-reservoir concept is invalidated and, consequently, also the assumption that the excess pressure is the component of pressure that can be attributed to wave travel and reflection.

Comparison of two ways of altering carpal tunnel pressure with ultrasound surface wave elastography.

PubMed

Cheng, Yu-Shiuan; Zhou, Boran; Kubo, Kazutoshi; An, Kai-Nan; Moran, Steven L; Amadio, Peter C; Zhang, Xiaoming; Zhao, Chunfeng

2018-06-06

Higher carpal tunnel pressure is related to the development of carpal tunnel syndrome. Currently, the measurement of carpal tunnel pressure is invasive and therefore, a noninvasive technique is needed. We previously demonstrated that speed of wave propagation through a tendon in the carpal tunnel measured by ultrasound elastography could be used as an indicator of carpal tunnel pressure in a cadaveric model, in which a balloon had to be inserted into the carpal tunnel to adjust the carpal tunnel pressure. However, the method for adjusting the carpal tunnel pressure in the cadaveric model is not applicable for the in vivo model. The objective of this study was to utilize a different technique to adjust carpal tunnel pressure via pressing the palm and to validate it with ultrasound surface wave elastography in a human cadaveric model. The outcome was also compared with a previous balloon insertion technique. Results showed that wave speed of intra-carpal tunnel tendon and the ratio of wave speed of intra-and outer-carpal tunnel tendons increased linearly with carpal tunnel pressure. Moreover, wave speed of intra carpal tunnel tendon via both ways of altering carpal tunnel pressure showed similar results with high correlation. Therefore, it was concluded that the technique of pressing the palm can be used to adjust carpal tunnel pressure, and pressure changes can be detected via ultrasound surface wave elastography in an ex vivo model. Future studies will utilize this technique in vivo to validate the usefulness of ultrasound surface wave elastography for measuring carpal tunnel pressure. Copyright © 2018 Elsevier Ltd. All rights reserved.

A Comparison between Oceanographic Parameters and Seafloor Pressures; Measured, Theoretical and Modelled, and Terrestrial Seismic Data

NASA Astrophysics Data System (ADS)

Donne, Sarah; Bean, Christopher; Craig, David; Dias, Frederic; Christodoulides, Paul

2016-04-01

Microseisms are continuous seismic vibrations which propagate mainly as surface Rayleigh and Love waves. They are generated by the Earth's oceans and there are two main types; primary and secondary microseisms. Primary microseisms are generated through the interaction of travelling surface gravity ocean waves with the seafloor in shallow waters relative to the wavelength of the ocean wave. Secondary microseisms, on the other hand are generated when two opposing wave trains interact and a non-linear second order effect produces a pressure fluctuation which is depth independent. The conditions necessary to produce secondary microseisms are presented in Longuet-Higgins (1950) through the interaction of two travelling waves with the same wave period and which interact at an angle of 180 degrees. Equivalent surface pressure density (p2l) is modelled using the numerical ocean wave model Wavewatch III and this term is considered as the microseism source term. This work presents an investigation of the theoretical second order pressures generated through the interaction of travelling waves with varying wave amplitude, period and angle of incidence. Predicted seafloor pressures calculated off the Southwest coast of Ireland are compared with terrestrially recorded microseism records, measured seafloor pressures and oceanographic parameters. The work presented in this study suggests that a broad set of sea states can generate second order seafloor pressures that are consistent with seafloor pressure measurements. Local seismic arrays throughout Ireland allow us to investigate the temporal covariance of these seafloor pressures with microseism source locations.

Winds, waves and shorelines from ancient martian seas

NASA Astrophysics Data System (ADS)

Banfield, Don; Donelan, Mark; Cavaleri, Luigi

2015-04-01

We consider under what environmental conditions water waves (and thus eventually shorelines) should be expected to be produced on hypothetical ancient martian seas and lakes. For winds and atmospheric pressures that are too small, no waves should be expected, and thus no shorelines. If the winds and atmospheric pressure are above some threshold, then waves can be formed, and shorelines are possible. We establish these criteria separating conditions under which waves will or will not form on an ancient martian open body of water. We consider not only atmospheric pressure and wind, but also temperature and salinity, but find these latter effects to be secondary. The normal criterion for the onset of water waves under terrestrial conditions is extended to recognize the greater atmospheric viscous boundary layer depth for low atmospheric pressures. We used terrestrial wave models to predict the wave environment expected for reasonable ranges of atmospheric pressure and wind for end-member cases of ocean salinity. These models were modified only to reflect the different fluids considered at Mars, the different martian surface gravity, and the varying atmospheric pressure, wind and fetch. The models were favorably validated against one another, and also against experiments conducted in a wave tank in a pressure controlled wind tunnel (NASA Ames MARSWIT). We conclude that if wave-cut shorelines can be confirmed on Mars, this can constrain the range of possible atmospheric pressures and wind speeds that could have existed when the open water was present on Mars.

Generation of intermittent gravitocapillary waves via parametric forcing

NASA Astrophysics Data System (ADS)

Castillo, Gustavo; Falcón, Claudio

2018-04-01

We report on the generation of an intermittent wave field driven by a horizontally moving wave maker interacting with Faraday waves. The spectrum of the local gravitocapillary surface wave fluctuations displays a power law in frequency for a wide range of forcing parameters. We compute the probability density function of the local surface height increments, which show that they change strongly across time scales. The structure functions of these increments are shown to display power laws as a function of the time lag, with exponents that are nonlinear functions of the order of the structure function. We argue that the origin of this scale-invariant intermittent spectrum is the Faraday wave pattern breakup due to its advection by the propagating gravity waves. Finally, some interpretations are proposed to explain the appearance of this intermittent spectrum.

Modeling of wave-coherent pressures in the turbulent boundary layer above water waves

NASA Technical Reports Server (NTRS)

Papadimitrakis, Yiannis ALEX.

1988-01-01

The behavior of air pressure fluctuations induced by progressive water waves generated mechanically in a laboratory tank was simulated by solving a modified Orr-Sommerfeld equation in a transformed Eulerian wave-following frame of reference. Solution is obtained by modeling the mean and wave-coherent turbulent Reynolds stresses, the behavior of which in the turbulent boundary layer above the waves was simulated using a turbulent kinetic energy-dissipation model, properly modified to account for free-surface proximity and favorable pressure gradient effects. The distribution of both the wave-coherent turbulent Reynolds stress and pressure amplitudes and their corresponding phase lags was found to agree reasonably well with available laboratory data.

Linear and nonlinear 2D finite element analysis of sloshing modes and pressures in rectangular tanks subject to horizontal harmonic motions

NASA Astrophysics Data System (ADS)

Virella, Juan C.; Prato, Carlos A.; Godoy, Luis A.

2008-05-01

The influence of nonlinear wave theory on the sloshing natural periods and their modal pressure distributions are investigated for rectangular tanks under the assumption of two-dimensional behavior. Natural periods and mode shapes are computed and compared for both linear wave theory (LWT) and nonlinear wave theory (NLWT) models, using the finite element package ABAQUS. Linear wave theory is implemented in an acoustic model, whereas a plane strain problem with large displacements is used in NLWT. Pressure distributions acting on the tank walls are obtained for the first three sloshing modes using both linear and nonlinear wave theory. It is found that the nonlinearity does not have significant effects on the natural sloshing periods. For the sloshing pressures on the tank walls, different distributions were found using linear and nonlinear wave theory models. However, in all cases studied, the linear wave theory conservatively estimated the magnitude of the pressure distribution, whereas larger pressures resultant heights were obtained when using the nonlinear theory. It is concluded that the nonlinearity of the surface wave does not have major effects in the pressure distribution on the walls for rectangular tanks.

Comparison of three portable instruments to measure compression pressure.

PubMed

Partsch, H; Mosti, G

2010-10-01

Measurement of interface pressure between the skin and a compression device has gained practical importance not only for characterizing the efficacy of different compression products in physiological and clinical studies but also for the training of medical staff. A newly developed portable pneumatic pressure transducer (Picopress®) was compared with two established systems (Kikuhime® and SIGaT tester®) measuring linearity, variability and accuracy on a cylindrical model using a stepwise inflated sphygmomanometer as the reference. In addition the variation coefficients were measured by applying the transducers repeatedly under a blood pressure cuff on the distal lower leg of a healthy human subject with stepwise inflation. In the pressure range between 10 and 80 mmHg all three devices showed a linear association compared with the sphygmomanometer values (Pearson r>0.99). The best reproducibility (variation coefficients between 1.05-7.4%) and the highest degree of accuracy demonstrated by Bland-Altman plots was achieved with the Picopress® transducer. Repeated measurements of pressure in a human leg revealed average variation coefficients for the three devices of 4.17% (Kikuhime®), 8.52% (SIGaT®) and 2.79% (Picopress®). The results suggest that the Picopress® transducer, which also allows dynamic pressure tracing in connection with a software program and which may be left under a bandage for several days, is a reliable instrument for measuring the pressure under a compression device.

Development Specification for the Portable Life Support System (PLSS) Thermal Loop Pump

NASA Technical Reports Server (NTRS)

Anchondo, Ian; Campbell, Colin

2017-01-01

The AEMU Thermal Loop Pump Development Specification establishes the requirements for design, performance, and testing of the Water Pump as part of the Thermal System of the Advanced Portable Life Support System (PLSS). It is envisioned that the Thermal Loop Pump is a positive displacement pump that provides a repeatable volume of flow against a given range of back-pressures provided by the various applications. The intention is to operate the pump at a fixed speed for the given application. The primary system is made up of two identical and redundant pumps of which only one is in operation at given time. The Auxiliary Loop Pump is an identical pump design to the primary pumps but is operated at half the flow rate. Inlet positive pressure to the pumps is provided by the upstream Flexible Supply Assembly (FSA-431 and FSA-531) which are physically located inside the suit volume and pressurized by suit pressure. An integrated relief valve, placed in parallel to the pump's inlet and outlet protects the pump and loop from over-pressurization. An integrated course filter is placed upstream of the pump's inlet to provide filtration and prevent potential debris from damaging the pump.

A midsummer-night's shock wave

NASA Astrophysics Data System (ADS)

Hargather, Michael; Liebner, Thomas; Settles, Gary

2007-11-01

The aerial pyrotechnic shells used in professional display fireworks explode a bursting charge at altitude in order to disperse the ``stars'' of the display. The shock wave from the bursting charge is heard on the ground as a loud report, though it has by then typically decayed to a mere sound wave. However, viewers seated near the standard safety borders can still be subjected to weak shock waves. These have been visualized using a large, portable, retro-reflective ``Edgerton'' shadowgraph technique and a high-speed digital video camera. Images recorded at 10,000 frames per second show essentially-planar shock waves from 10- and 15-cm firework shells impinging on viewers during the 2007 Central Pennsylvania July 4th Festival. The shock speed is not measurably above Mach 1, but we nonetheless conclude that, if one can sense a shock-like overpressure, then the wave motion is strong enough to be observed by density-sensitive optics.

Evaluating The Relation of Trace Fracture Inclination and Sound Pressure Level and Time-of-flight QUS Parameters Using Computational Simulation

NASA Astrophysics Data System (ADS)

Rosa, P. T.; Fontes-Pereira, A. J.; Matusin, D. P.; von Krüger, M. A.; Pereira, W. C. A.

Bone healing is a complex process that stars after the occurrence of a fracture to restore bone optimal conditions. The gold standards for bone status evaluation are the dual energy X-ray absorptiometry and the computerized tomography. Ultrasound-based technologies have some advantages as compared to X-ray technologies: nonionizing radiation, portability and lower cost among others. Quantitative ultrasound (QUS) has been proposed in literature as a new tool to follow up the fracture healing process. QUS relates the ultrasound propagation with the bone tissue condition (normal or pathological), so, a change in wave propagation may indicate a variation in tissue properties. The most used QUS parameters are time-of-flight (TOF) and sound pressure level (SPL) of the first arriving signal (FAS). In this work, the FAS is the well known lateral wave. The aim of this work is to evaluate the relation of the TOF and SPL of the FAS and fracture inclination trace in two stages of bone healing using computational simulations. Four fracture geometries were used: normal and oblique with 30, 45 and 60 degrees. The TOF average values were 63.23 μs, 63.14 μs, 63.03 μs 62.94 μs for normal, 30, 45 and 60 degrees respectively and average SPL values were -3.83 dB -4.32 dB, -4.78 dB, -6.19 dB for normal, 30, 45 and 60 degrees respectively. The results show an inverse pattern between the amplitude and time-of-flight. These values seem to be sensible to fracture inclination trace, and in future, can be used to characterize it.

Characterization of a Setup to test the Impact of High-Amplitude Pressure Waves on Living Cells

PubMed Central

Schmidt, Mischa; Kahlert, Ulf; Wessolleck, Johanna; Maciaczyk, Donata; Merkt, Benjamin; Maciaczyk, Jaroslaw; Osterholz, Jens; Nikkhah, Guido; Steinhauser, Martin O.

2014-01-01

The impact of pressure waves on cells may provide several possible applications in biology and medicine including the direct killing of tumors, drug delivery or gene transfection. In this study we characterize the physical properties of mechanical pressure waves generated by a nanosecond laser pulse in a setup with well-defined cell culture conditions. To systematically characterize the system on the relevant length and time scales (micrometers and nanoseconds) we use photon Doppler velocimetry (PDV) and obtain velocity profiles of the cell culture vessel at the passage of the pressure wave. These profiles serve as input for numerical pressure wave simulations that help to further quantify the pressure conditions on the cellular length scale. On the biological level we demonstrate killing of glioblastoma cells and quantify experimentally the pressure threshold for cell destruction. PMID:24458018

Fluid-structure interaction dynamic simulation of spring-loaded pressure relief valves under seismic wave

NASA Astrophysics Data System (ADS)

Lv, Dongwei; Zhang, Jian; Yu, Xinhai

2018-05-01

In this paper, a fluid-structure interaction dynamic simulation method of spring-loaded pressure relief valve was established. The dynamic performances of the fluid regions and the stress and strain of the structure regions were calculated at the same time by accurately setting up the contact pairs between the solid parts and the coupling surfaces between the fluid regions and the structure regions. A two way fluid-structure interaction dynamic simulation of a simplified pressure relief valve model was carried out. The influence of vertical sinusoidal seismic waves on the performance of the pressure relief valve was preliminarily investigated by loading sine waves. Under vertical seismic waves, the pressure relief valve will flutter, and the reseating pressure was affected by the amplitude and frequency of the seismic waves. This simulation method of the pressure relief valve under vertical seismic waves can provide effective means for investigating the seismic performances of the valves, and make up for the shortcomings of the experiment.

Relationship between orientation to a blast and pressure wave propagation inside the rat brain.

PubMed

Chavko, Mikulas; Watanabe, Tomas; Adeeb, Saleena; Lankasky, Jason; Ahlers, Stephen T; McCarron, Richard M

2011-01-30

Exposure to a blast wave generated during an explosion may result in brain damage and related neurological impairments. Several mechanisms by which the primary blast wave can damage the brain have been proposed, including: (1) a direct effect of the shock wave on the brain causing tissue damage by skull flexure and propagation of stress and shear forces; and (2) an indirect transfer of kinetic energy from the blast, through large blood vessels and cerebrospinal fluid (CSF), to the central nervous system. To address a basic question related to the mechanisms of blast brain injury, pressure was measured inside the brains of rats exposed to a low level of blast (~35kPa), while positioned in three different orientations with respect to the primary blast wave; head facing blast, right side exposed to blast and head facing away from blast. Data show different patterns and durations of the pressure traces inside the brain, depending on the rat orientation to blast. Frontal exposures (head facing blast) resulted in pressure traces of higher amplitude and longer duration, suggesting direct transmission and reflection of the pressure inside the brain (dynamic pressure transfer). The pattern of the pressure wave inside the brain in the head facing away from blast exposures assumes contribution of the static pressure, similar to hydrodynamic pressure to the pressure wave inside the brain. Published by Elsevier B.V.

Piezoresistive method for a laser induced shock wave detection on solids

NASA Astrophysics Data System (ADS)

Gonzalez-Romero, R.; Garcia-Torales, G.; Gomez Rosas, G.; Strojnik, M.

2017-08-01

A laser shock wave is a mechanical high-pressure impulse with a duration of a few nanoseconds induced by a high power laser pulse. We performed wave pressure measurements in order to build and check mathematical models. They are used for wave applications in material science, health, and defense, to list a few. Piezoresistive methods have been shown to be highly sensitive, linear, and highly appropriate for practical implementation, compared with piezoelectric methods employed in shock wave pressure measurements. In this work, we develop a novel method to obtain the sensitivity of a piezoresistive measurement system. The results shows that it is possible to use a mechanical method to measure pressure of a laser induced shock wave in nanosecond range. Experimental pressure measurements are presented.

A Non-Intrusive Pressure Sensor by Detecting Multiple Longitudinal Waves

PubMed Central

Zhou, Hongliang; Lin, Weibin; Ge, Xiaocheng; Zhou, Jian

2016-01-01

Pressure vessels are widely used in industrial fields, and some of them are safety-critical components in the system—for example, those which contain flammable or explosive material. Therefore, the pressure of these vessels becomes one of the critical measurements for operational management. In the paper, we introduce a new approach to the design of non-intrusive pressure sensors, based on ultrasonic waves. The model of this sensor is built based upon the travel-time change of the critically refracted longitudinal wave (LCR wave) and the reflected longitudinal waves with the pressure. To evaluate the model, experiments are carried out to compare the proposed model with other existing models. The results show that the proposed model can improve the accuracy compared to models based on a single wave. PMID:27527183

Calculation Of Pneumatic Attenuation In Pressure Sensors

NASA Technical Reports Server (NTRS)

Whitmore, Stephen A.

1991-01-01

Errors caused by attenuation of air-pressure waves in narrow tubes calculated by method based on fundamental equations of flow. Changes in ambient pressure transmitted along narrow tube to sensor. Attenuation of high-frequency components of pressure wave calculated from wave equation derived from Navier-Stokes equations of viscous flow in tube. Developed to understand and compensate for frictional attenuation in narrow tubes used to connect aircraft pressure sensors with pressure taps on affected surfaces.

Forward and Backward Pressure Waveform Morphology in Hypertension

PubMed Central

Li, Ye; Gu, Haotian; Fok, Henry; Alastruey, Jordi

2017-01-01

We tested the hypothesis that increased pulse wave reflection and altered backward waveform morphology contribute to increased pulse pressure in subjects with higher pulse pressure compared with lower pulse pressure and to actions of vasoactive drugs to increase pulse pressure. We examined the relationship of backward to forward wave morphology in 158 subjects who were evaluated for hypertension (including some normotensive subjects) divided into 3 groups by central pulse pressure: group 1, 33±6.5 mm Hg; group 2, 45±4.1 mm Hg; and group 3, 64±12.9 mm Hg (means±SD) and in healthy normotensive subjects during administration of inotropic and vasomotor drugs. Aortic pressure and flow in the aortic root were estimated by carotid tonometry and Doppler sonography, respectively. Morphology of the backward wave relative to the forward wave was similar in subjects in the lowest and highest tertiles of pulse pressure. Similar results were seen with the inotropic, vasopressor and vasodilator drugs, dobutamine, norepinephrine, and phentolamine, with the backward wave maintaining a constant ratio to the forward wave. However, nitroglycerin, a drug with a specific action to dilate muscular conduit arteries, reduced the amplitude of the backward wave relative to the forward wave from 0.26±0.018 at baseline to 0.19±0.019 during nitroglycerin 30 μg/min IV (P<0.01). These results are best explained by an approximately constant amount of reflection of the forward wave from the peripheral vasculature. The amount of reflection can be modified by dilation of peripheral muscular conduit arteries but contributes little to increased pulse pressure in hypertension. PMID:27920128

77 FR 53159 - Passenger Use of Portable Electronic Devices on Board Aircraft

Federal Register 2010, 2011, 2012, 2013, 2014

2012-08-31

... to navigation systems such as very high frequency (VHF) Omni Range (VOR) navigation systems. \\1\\ 14... navigation, communication, and surveillance radio receivers that may be susceptible at certain frequencies to... space by electromagnetic waves on specific radio frequencies that are used to communicate information...

Laboratory tests of short intense envelope solitons

NASA Astrophysics Data System (ADS)

Slunyaev, A.; Clauss, G. F.; Klein, M.; Onorato, M.

2012-04-01

Stability of short intense nonlinear wave groups propagating over deep water is tested in laboratory runs which are performed in the facility of the Technical University of Berlin. The strongly nonlinear simulation of quasi-steady nonlinear wave groups within the framework of the Euler equations is used to generate the surface elevation time series at a border of the water tank. Besides, the exact analytic solution of the nonlinear Schrodinger equation is used for this purpose. The time series is then transformed to a wave maker signal with use of a designed transfer algorithm. Wave group propagation along the tank was recorded by 4 distant gauges and by an array of 6 densely situated gauges. This setup allows to consider the wave evolution from 10 to 85 m from the wave maker, and to obtain the wave envelope shape directly from the instrumental data. In the experiments wave groups were characterized by the steepness values up to kAcr < 0.32 and kAtr < 0.24, where k is the mean wavenumber, Acr is the crest amplitude, and Atr is the trough amplitude; and the maximum local wave slope was up to 0.34. Wave breaking phenomenon was not observed in the experiments. Different mean wave numbers and wave groups of different intensities were considered. In some cases the wave groups exhibit noticeable radiation in the course of propagation, though the groups are not dispersed fully. The effect of finite water depth is found to be significant on the wave group stability. Intense wave groups have shorter time of adjustment, what in some sense may help them to manifest their individuality clearer. The experimental tests confirm recent numerical simulations of fully nonlinear equations, where very steep stable single and interacting nonlinear wave groups were reported [1-3]. The quasi-stationary wave groups observed in numerical and laboratory experiments are strongly nonlinear analogues of the nonlinear Schrodinger envelope solitons. The results emphasize the importance of long-living nonlinear wave groups in dynamics of intense sea waves. [1] V.E. Zakharov, A.I. Dyachenko, A.O. Prokofiev, Eur. J. Mech. B / Fluids 25, 677 (2006). [2] A.I. Dyachenko, V.E. Zakharov, JETP Lett. 88, 307 (2008). [3] A.V. Slunyaev, JETP 109, 676 (2009).

Similar Pressures, Different Contexts: Public Attitudes toward Government Intervention for Health Care in 21 Nations

ERIC Educational Resources Information Center

Kikuzawa, Saeko; Olafsdottir, Sigrun; Pescosolido, Bernice A.

2008-01-01

Health care systems worldwide are experiencing similar pressures such as rising cost, aging populations, and increased burden of disease. While policy makers in all countries face these challenges, their responses must consider local pressures, particularly the implicit social contract between the state, medicine, and insurers. We argue that…

The effects of pressure, temperature, and pore water on velocities in Westerly granite. [for seismic wave propagation

NASA Technical Reports Server (NTRS)

Spencer, J. W., Jr.; Nur, A. M.

1976-01-01

A description is presented of an experimental assembly which has been developed to conduct concurrent measurements of compressional and shear wave velocities in rocks at high temperatures and confining pressures and with independent control of the pore pressure. The apparatus was used in studies of the joint effects of temperature, external confining pressure, and internal pore water on sonic velocities in Westerly granite. It was found that at a given temperature, confining pressure has a larger accelerating effect on compressional waves in dry rock, whereas at a given confining pressure, temperature has a larger retarding effect on shear waves.

Exploring microdischarges for portable sensing applications.

PubMed

Gianchandani, Y B; Wright, S A; Eun, C K; Wilson, C G; Mitra, B

2009-10-01

This paper describes the use of microdischarges as transducing elements in sensors and detectors. Chemical and physical sensing of gases, chemical sensing of liquids, and radiation detection are described. These applications are explored from the perspective of their use in portable microsystems, with emphasis on compactness, power consumption, the ability to operate at or near atmospheric pressure (to reduce pumping challenges), and the ability to operate in an air ambient (to reduce the need for reservoirs of carrier gases). Manufacturing methods and performance results are described for selected examples.

Mode Identification of High-Amplitude Pressure Waves in Liquid Rocket Engines

NASA Astrophysics Data System (ADS)

EBRAHIMI, R.; MAZAHERI, K.; GHAFOURIAN, A.

2000-01-01

Identification of existing instability modes from experimental pressure measurements of rocket engines is difficult, specially when steep waves are present. Actual pressure waves are often non-linear and include steep shocks followed by gradual expansions. It is generally believed that interaction of these non-linear waves is difficult to analyze. A method of mode identification is introduced. After presumption of constituent modes, they are superposed by using a standard finite difference scheme for solution of the classical wave equation. Waves are numerically produced at each end of the combustion tube with different wavelengths, amplitudes, and phases with respect to each other. Pressure amplitude histories and phase diagrams along the tube are computed. To determine the validity of the presented method for steep non-linear waves, the Euler equations are numerically solved for non-linear waves, and negligible interactions between these waves are observed. To show the applicability of this method, other's experimental results in which modes were identified are used. Results indicate that this simple method can be used in analyzing complicated pressure signal measurements.

[Research and development of portable hypertension therapeutic apparatus based on biofeedback mechanism].

PubMed

Huang, Rong; He, Hongmei; Pi, Xitian; Diao, Ziji; Zhao, Suwen

2014-06-01

Non-drug treatment of hypertension has become a research hotspot, which might overcome the heavy economic burden and side effects of drug treatment for the patients. Because of the good treatment effect and convenient operation, a new treatment based on slow breathing training is increasingly becoming a kind of physical therapy for hypertension. This paper explains the principle of hypertension treatment based on slow breathing training method, and introduces the overall structure of the portable blood pressure controlling instrument, including breathing detection circuit, the core control module, audio module, memory module and man-machine interaction module. We give a brief introduction to the instrument and the software in this paper. The prototype testing results showed that the treatment had a significant effect on controlling the blood pressure.

Study on Pressure Wave Propagation in a Liquid Containing Spherical Bubbles in a Rectangular Duct

NASA Astrophysics Data System (ADS)

Kawahara, Junya; Watanabe, Masao; Kobayashi, Kazumichi

2015-12-01

Pressure wave propagation in a liquid containing several bubbles is numerically investigated. We simulate liner plane wave propagation in a liquid containing 10 spherical bubbles in a rectangular duct with the equation of motion for N spherical bubbles. The sound pressures of the reflected waves from the rigid walls are calculated by using the method of images. The result shows that the phase velocity of the pressure wave propagating in the liquid containing 10 spherical bubbles in the duct agrees well with the low-frequency speed of sound in a homogeneous bubbly liquid.

Toe pressure determination by audiophotoplethysmography.

PubMed

Fronek, A; Blazek, V; Curran, B

1994-08-01

The purpose of this study was to evaluate the performance of audiophotoplethysmography as a modality to measure toe pressure without the requirement of a recorder. A portable photoplethysmograph with an audio output was used to determine toe pressures, and the results were compared with those obtained by a commercial photoplethysmograph with a recorder. Thirty-one measurements in control subjects and 62 measurements in patients with arterial occlusive disease were performed. The average toe pressure recorded with oscillography with standard photoplethysmography was 103.5 mm Hg +/- 14.7 SD and 95.9 mm Hg +/- 13.4 SD with audio-photoplethysmography. In the patient group the pressure recorded with a commercial photoplethysmograph was 65.3 mm Hg +/- 34.9 SD compared with 61.6 mm Hg +/- 34.8 SD obtained with audio-photoplethysmography. The difference in both groups was insignificant, and the correlation between both methods was very good. A portable hand-held photoplethysmograph equipped with an audio output was used to measure toe pressure in control subjects and in patients with arterial occlusive disease. The results have been compared with the oscillometric method by a standard commercial photoplethysmograph connected to a recorder. The correlation was very good in the control and patient groups, and the difference between both methods was below the level of statistical significance. The fact that no recorder is needed may help in introducing toe pressure measurement into everyday office diagnostic practice.

Corotating pressure waves without streams in the solar wind

NASA Technical Reports Server (NTRS)

Burlaga, L. F.

1983-01-01

Voyager 1 and 2 magnetic field and plasma data are presented which demonstrate the existence of large scale, corotating, non-linear pressure waves between 2 AU and 4 AU that are not accompanied by fast streams. The pressure waves are presumed to be generated by corotating streams near the Sun. For two of the three pressure waves that are discussed, the absence of a stream is probably a real, physical effect, viz., a consequence of deceleration of the stream by the associated compression wave. For the third pressure wave, the apparent absence of a stream may be a geometrical effect; it is likely that the stream was at latitudes just above those of the spacecraft, while the associated shocks and compression wave extended over a broader range of latitudes so that they could be observed by the spacecraft. It is suggested that the development of large-scale non-linear pressure waves at the expense of the kinetic energy of streams produces a qualitative change in the solar wind in the outer heliosphere. Within a few AU the quasi-stationary solar wind structure is determined by corotating streams whose structure is determined by the boundary conditions near the Sun.

Observations of height-dependent pressure-perturbation structure of a strong mesoscale gravity wave

NASA Technical Reports Server (NTRS)

Starr, David O'C.; Korb, C. L.; Schwemmer, Geary K.; Weng, Chi Y.

1992-01-01

Airborne observations using a downward-looking, dual-frequency, near-infrared, differential absorption lidar system provide the first measurements of the height-dependent pressure-perturbation field associated with a strong mesoscale gravity wave. A pressure-perturbation amplitude of 3.5 mb was measured within the lowest 1.6 km of the atmosphere over a 52-km flight line. Corresponding vertical displacements of 250-500 m were inferred from lidar-observed displacement of aerosol layers. Accounting for probable wave orientation, a horizontal wavelength of about 40 km was estimated. Satellite observations reveal wave structure of a comparable scale in concurrent cirrus cloud fields over an extended area. Smaller-scale waves were also observed. Local meteorological soundings are analyzed to confirm the existence of a suitable wave duct. Potential wave-generation mechanisms are examined and discussed. The large pressure-perturbation wave is attributed to rapid amplification or possible wave breaking of a gravity wave as it propagated offshore and interacted with a very stable marine boundary layer capped by a strong shear layer.

EVOLUTION of the Pressure Wave Supercharger Concept

NASA Astrophysics Data System (ADS)

Costiuc, Iuliana; Chiru, Anghel

2017-10-01

Born more than a century ago, the concept of exploiting the pressure wave phenomenon has evolved with rather small steps, experiencing an accelerated progress over the past decades. This paper aims an overview on the researchers’ results over time regarding the pressure wave technology and its applications, pointing out on the internal combustion engine’s supercharging application. This review complements the past reports on the subject, presenting the evolution of the concept and technology, as well as the researcher’s efforts on solving the specific shortcomings of this pressure wave technology. Undoubtedly, the pressure wave rotors have been a research goal over the years. At first, most of the researches were experimental and the theoretical calculations required to improve the technology were too arduous. Recently, new computer software dedicated to accurate simulation of the processes governing the wave rotor operation, altogether with modern experimental measurement instruments and well-developed diagnostic techniques have opened wide possibilities to innovate the pressure wave supercharging technology. This paper also highlights the challenges that specialists still have to overcome and aspects to become future preoccupations and research directions.

Forward and Backward Pressure Waveform Morphology in Hypertension.

PubMed

Li, Ye; Gu, Haotian; Fok, Henry; Alastruey, Jordi; Chowienczyk, Philip

2017-02-01

We tested the hypothesis that increased pulse wave reflection and altered backward waveform morphology contribute to increased pulse pressure in subjects with higher pulse pressure compared with lower pulse pressure and to actions of vasoactive drugs to increase pulse pressure. We examined the relationship of backward to forward wave morphology in 158 subjects who were evaluated for hypertension (including some normotensive subjects) divided into 3 groups by central pulse pressure: group 1, 33±6.5 mm Hg; group 2, 45±4.1 mm Hg; and group 3, 64±12.9 mm Hg (means±SD) and in healthy normotensive subjects during administration of inotropic and vasomotor drugs. Aortic pressure and flow in the aortic root were estimated by carotid tonometry and Doppler sonography, respectively. Morphology of the backward wave relative to the forward wave was similar in subjects in the lowest and highest tertiles of pulse pressure. Similar results were seen with the inotropic, vasopressor and vasodilator drugs, dobutamine, norepinephrine, and phentolamine, with the backward wave maintaining a constant ratio to the forward wave. However, nitroglycerin, a drug with a specific action to dilate muscular conduit arteries, reduced the amplitude of the backward wave relative to the forward wave from 0.26±0.018 at baseline to 0.19±0.019 during nitroglycerin 30 μg/min IV (P<0.01). These results are best explained by an approximately constant amount of reflection of the forward wave from the peripheral vasculature. The amount of reflection can be modified by dilation of peripheral muscular conduit arteries but contributes little to increased pulse pressure in hypertension. © 2016 The Authors.

Influence of flow and pressure on wave propagation in the canine aorta.

NASA Technical Reports Server (NTRS)

Histand, M. B.; Anliker, M.

1973-01-01

Data on wave speed acquired from 20 anesthetized dogs showed that the thoracic aorta was essentially nondispersive for small artificially generated pressure waves traveling in the downstream or the upstream direction and having frequencies between 40 and 120 Hz. The amplitude of these waves decayed exponentially with the distance traveled. Theoretical studies are cited which have shown that changes in wave speed due to variations in pressure and flow produce marked nonlinear effects in hemodynamics.

Novel wave power analysis linking pressure-flow waves, wave potential, and the forward and backward components of hydraulic power.

PubMed

Mynard, Jonathan P; Smolich, Joseph J

2016-04-15

Wave intensity analysis provides detailed insights into factors influencing hemodynamics. However, wave intensity is not a conserved quantity, so it is sensitive to diameter variations and is not distributed among branches of a junction. Moreover, the fundamental relation between waves and hydraulic power is unclear. We, therefore, propose an alternative to wave intensity called "wave power," calculated via incremental changes in pressure and flow (dPdQ) and a novel time-domain separation of hydraulic pressure power and kinetic power into forward and backward wave-related components (ΠP±and ΠQ±). Wave power has several useful properties:1) it is obtained directly from flow measurements, without requiring further calculation of velocity;2) it is a quasi-conserved quantity that may be used to study the relative distribution of waves at junctions; and3) it has the units of power (Watts). We also uncover a simple relationship between wave power and changes in ΠP±and show that wave reflection reduces transmitted power. Absolute values of ΠP±represent wave potential, a recently introduced concept that unifies steady and pulsatile aspects of hemodynamics. We show that wave potential represents the hydraulic energy potential stored in a compliant pressurized vessel, with spatial gradients producing waves that transfer this energy. These techniques and principles are verified numerically and also experimentally with pressure/flow measurements in all branches of a central bifurcation in sheep, under a wide range of hemodynamic conditions. The proposed "wave power analysis," encompassing wave power, wave potential, and wave separation of hydraulic power provides a potent time-domain approach for analyzing hemodynamics. Copyright © 2016 the American Physiological Society.

An Investigation Into the Range of Sea State Conditions Necessary for the Generation of Seafloor Pressures and Secondary Microseisms in the Northeast Atlantic, West of Ireland

NASA Astrophysics Data System (ADS)

Donne, S. E.; Bean, C. J.; Dias, F.; Christodoulides, P.

2016-12-01

Ocean generated microseisms propagate mainly as Rayleigh and Love waves and are a result of the mechanical coupling between the ocean and the solid earth. There are two types of microseism, primary and secondary. Primary microseisms are generated when a travelling ocean wave enters shallow water or coastal regions and the associated pressure profile, which decays exponentially with depth, is non zero at the seafloor. Secondary microseisms on the other hand are generated by the second order non linear effect associated with a standing wave, through ocean wave- wave interactions. Secondary microseisms can therefore be generated in any water depth. The conditions required to generate secondary microseisms through wave- wave interactions are presented in Longuet-Higgins (1950) through the interaction of two travelling waves with the same wave period at an angle of 180 degrees. Equivalent surface pressure density (p2l) is modelled within the numerical ocean wave model, Wavewatch III and is the microseism source term. This work investigates the theoretical pressures associated with the interaction of two travelling waves with varying wave periods and wave amplitude at a range of incident angles. Theoretical seafloor pressures are calculated off the Southwest coast of Ireland and are compared with terrestrially recorded microseism data as well as oceanographic parameters and measured seafloor pressures. The results indicate that a broad range of sea state conditions can generate second order pressures at the seafloor which are consistent with measured seafloor measurements in the same location. While secondary microseism amplitudes may be used to infer ocean wave parameters this work has implications for doing so and these will be presented. Local seismic arrays in Ireland allow us to monitor and track the spatiotemporal evolution of these microseism source regions.

Pneumatic pressure wave generator provides economical, simple testing of pressure transducers

NASA Technical Reports Server (NTRS)

Gaal, A. E.; Weldon, T. P.

1967-01-01

Testing device utilizes the change in pressure about a bias or reference pressure level produced by displacement of a center-driven piston in a closed cylinder. Closely controlled pneumatic pressure waves allow testing under dynamic conditions.

The detection of organophosphonates by polymer films on a surface acoustic wave device and a micromirror fiber optic sensor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hughes, R.C.; Ricco, A.J.; Butler, M.A.

There is a need for sensitive detection of organophosphonates by, inexpensive, portable instruments. Two kinds of chemical sensors, based on surface acoustic wave (SAW) devices and fiber optic micromirrors, show promise for such sensing systems. Chemically sensitive coatings are required for detection and data for thin films of the polymer polysiloxane are reported for both kinds of physical transducers. Both kinds of sensor are shown to be capable of detecting concentrations of diisopropylmethylphosphonate (DIMP) down to 1 ppM.

Measurement of beam profiles by terahertz sensor card with cholesteric liquid crystals.

PubMed

Tadokoro, Yuzuru; Nishikawa, Tomohiro; Kang, Boyoung; Takano, Keisuke; Hangyo, Masanori; Nakajima, Makoto

2015-10-01

We demonstrate a sensor card with cholesteric liquid crystals (CLCs) for terahertz (THz) waves generated from a nonlinear crystal pumped by a table-top laser. A beam profile of the THz waves is successfully visualized as color change by the sensor card without additional electronic devices, power supplies, and connecting cables. Above the power density of 4.3  mW/cm2, the approximate beam diameter of the THz waves is measured using the hue image that is digitalized from the picture of the sensor card. The sensor card is low in cost, portable, and suitable for various situations such as THz imaging and alignment of THz systems.

Pressure wave propagation in fluid-filled co-axial elastic tubes. Part 1: Basic theory.

PubMed

Berkouk, K; Carpenter, P W; Lucey, A D

2003-12-01

Our work is motivated by ideas about the pathogenesis of syringomyelia. This is a serious disease characterized by the appearance of longitudinal cavities within the spinal cord. Its causes are unknown, but pressure propagation is probably implicated. We have developed an inviscid theory for the propagation of pressure waves in co-axial, fluid-filled, elastic tubes. This is intended as a simple model of the intraspinal cerebrospinal-fluid system. Our approach is based on the classic theory for the propagation of longitudinal waves in single, fluid-filled, elastic tubes. We show that for small-amplitude waves the governing equations reduce to the classic wave equation. The wave speed is found to be a strong function of the ratio of the tubes' cross-sectional areas. It is found that the leading edge of a transmural pressure pulse tends to generate compressive waves with converging wave fronts. Consequently, the leading edge of the pressure pulse steepens to form a shock-like elastic jump. A weakly nonlinear theory is developed for such an elastic jump.

Laser-driven Mach waves for gigabar-range shock experiments

NASA Astrophysics Data System (ADS)

Swift, Damian; Lazicki, Amy; Coppari, Federica; Saunders, Alison; Nilsen, Joseph

2017-10-01

Mach reflection offers possibilities for generating planar, supported shocks at higher pressures than are practical even with laser ablation. We have studied the formation of Mach waves by algebraic solution and hydrocode simulation for drive pressures at much than reported previously, and for realistic equations of state. We predict that Mach reflection continues to occur as the drive pressure increases, and the pressure enhancement increases monotonically with drive pressure even though the ``enhancement spike'' characteristic of low-pressure Mach waves disappears. The growth angle also increases monotonically with pressure, so a higher drive pressure seems always to be an advantage. However, there are conditions where the Mach wave is perturbed by reflections. We have performed trial experiments at the Omega facility, using a laser-heated halfraum to induce a Mach wave in a polystyrene cone. Pulse length and energy limitations meant that the drive was not maintained long enough to fully support the shock, but the results indicated a Mach wave of 25-30 TPa from a drive pressure of 5-6 TPa, consistent with simulations. A similar configuration should be tested at the NIF, and a Z-pinch driven configuration may be possible. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Laser-driven Mach waves for gigabar-range shock experiments

NASA Astrophysics Data System (ADS)

Swift, Damian; Jenei, Amy; Coppari, Federica; Saunders, Alison; Nilsen, Joseph

2017-06-01

Mach reflection offers possibilities for generating planar, supported shocks at higher pressures than are practical even with laser ablation. We have studied the formation of Mach waves by algebraic solution and hydrocode simulation for drive pressures at much than reported previously, and for realistic equations of state. We predict that Mach reflection continues to occur as the drive pressure increases, and the pressure enhancement increases monotonically with drive pressure even though the ``enhancement spike'' characteristic of low-pressure Mach waves disappears. The growth angle also increases monotonically with pressure, so a higher drive pressure seems always to be an advantage. However, there are conditions where the Mach wave is perturbed by reflections. We have performed trial experiments at the Omega facility, using a laser-heated halfraum to induce a Mach wave in a polystyrene cone. Pulse length and energy limitations meant that the drive was not maintained long enough to fully support the shock, but the results indicated a Mach wave of 25-30 TPa from a drive pressure of 5-6 TPa, consistent with simulations. A similar configuration should perform well at the NIF, and a Z-pinch driven configuration may be possible. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

A wireless handheld probe with spectrally constrained evolution strategies for diffuse optical imaging of tissue

NASA Astrophysics Data System (ADS)

Flexman, M. L.; Kim, H. K.; Stoll, R.; Khalil, M. A.; Fong, C. J.; Hielscher, A. H.

2012-03-01

We present a low-cost, portable, wireless diffuse optical imaging device. The handheld device is fast, portable, and can be applied to a wide range of both static and dynamic imaging applications including breast cancer, functional brain imaging, and peripheral artery disease. The continuous-wave probe has four near-infrared wavelengths and uses digital detection techniques to perform measurements at 2.3 Hz. Using a multispectral evolution algorithm for chromophore reconstruction, we can measure absolute oxygenated and deoxygenated hemoglobin concentration as well as scattering in tissue. Performance of the device is demonstrated using a series of liquid phantoms comprised of Intralipid®, ink, and dye.

Portable Unit for Metabolic Analysis

NASA Technical Reports Server (NTRS)

Dietrich, Daniel L.; Pitch, Nancy D.; Lewis, Mark E.; Juergens, Jeffrey R.; Lichter, Michael J.; Stuk, Peter M.; Diedrick, Dale M.; Valentine, Russell W.; Pettegrew, Richard D.

2007-01-01

The Portable Unit for Metabolic Analysis (PUMA) is an instrument that measures several quantities indicative of human metabolic function. Specifically, this instrument makes time-resolved measurements of temperature, pressure, flow, and the partial pressures of oxygen and carbon dioxide in breath during both inhalation and exhalation. Portable instruments for measuring these quantities have been commercially available, but the response times of those instruments are too long to enable temporal resolution of phenomena on the time scales of human respiration cycles. In contrast, the response time of the PUMA is significantly shorter than characteristic times of human respiration phenomena, making it possible to analyze varying metabolic parameters, not only on sequential breath cycles but also at successive phases of inhalation and exhalation within the same breath cycle. In operation, the PUMA is positioned to sample breath near the subject s mouth. Commercial off-the-shelf sensors are used for three of the measurements: a miniature pressure transducer for pressure, a thermistor for temperature, and an ultrasonic sensor for flow. Sensors developed at Glenn Research Center are used for measuring the partial pressures of oxygen and carbon dioxide: The carbon dioxide sensor exploits the relatively strong absorption of infrared light by carbon dioxide. Light from an infrared source passes through the stream of inhaled or exhaled gas and is focused on an infrared- sensitive photodetector. The oxygen sensor exploits the effect of oxygen in quenching the fluorescence of ruthenium-doped organic molecules in a dye on the tip of an optical fiber. A blue laser diode is used to excite the fluorescence, and the optical fiber carries the fluorescent light to a photodiode, the temporal variation of the output of which bears a known relationship with the rate of quenching of fluorescence and, hence, with the partial pressure of oxygen. The outputs of the sensors are digitized, preprocessed by a small onboard computer, and then sent wirelessly to a desktop computer, where the collected data are analyzed and displayed. In addition to the raw data on temperature, pressure, flow, and mole fractions of oxygen and carbon dioxide, the display can include volumetric oxygen consumption, volumetric carbon dioxide production, respiratory equivalent ratio, and volumetric flow rate of exhaled gas.

Breaking phase focused wave group loads on offshore wind turbine monopiles

NASA Astrophysics Data System (ADS)

Ghadirian, A.; Bredmose, H.; Dixen, M.

2016-09-01

The current method for calculating extreme wave loads on offshore wind turbine structures is based on engineering models for non-breaking regular waves. The present article has the aim of validating previously developed models at DTU, namely the OceanWave3D potential flow wave model and a coupled OceanWave3D-OpenFOAM solver, against measurements of focused wave group impacts on a monopile. The focused 2D and 3D wave groups are reproduced and the free surface elevation and the in-line forces are compared to the experimental results. In addition, the pressure distribution on the monopile is examined at the time of maximum force and discussed in terms of shape and magnitude. Relative pressure time series are also compared between the simulations and experiments and detailed pressure fields for a 2D and 3D impact are discussed in terms of impact type. In general a good match for free surface elevation, in-line force and wave-induced pressures is found.

Portable vibration exciter

NASA Technical Reports Server (NTRS)

Beecher, L. C.; Williams, F. T.

1970-01-01

Gas-driven vibration exciter produces a sinusoidal excitation function controllable in frequency and in amplitude. It allows direct vibration testing of components under normal loads, removing the possibility of component damage due to high static pressure.

A Portable Airborne Scanning Lidar System for Ocean and Coastal Applications

DTIC Science & Technology

2009-06-26

available online at http://www.ndbc.noaa.gov/) and Hs by the Coastal Data Information Program ( CDIP ) Station 100 (available online at http...storm events (Fig. 9). Significant wave height (Hs) for Novem- ber and December 2008, measured by CDIP station 043, located 2.7 km offshore of the

Short-wave infrared reflectance investigation of sites of paleobiological interest: applications for Mars exploration.

PubMed

Brown, Adrian; Walter, Malcolm; Cudahy, Thomas

2004-01-01

Rover missions to the rocky bodies of the Solar System and especially to Mars require lightweight, portable instruments that use minimal power, require no sample preparation, and provide suitably diagnostic mineralogical information to an Earth-based exploration team. Short-wave infrared (SWIR) spectroscopic instruments such as the Portable Infrared Mineral Analyser (PIMA, Integrated Spectronics Pty Ltd., Baulkham Hills, NSW, Australia) fulfill all these requirements. We describe an investigation of a possible Mars analogue site using a PIMA instrument. A survey was carried out on the Strelley Pool Chert, an outcrop of stromatolitic, silicified Archean carbonate and clastic succession in the Pilbara Craton, interpreted as being modified by hydrothermal processes. The results of this study demonstrate the capability of SWIR techniques to add significantly to the geological interpretation of such hydrothermally altered outcrops. Minerals identified include dolomite, white micas such as illite-muscovite, and chlorite. In addition, the detection of pyrophyllite in a bleached and altered unit directly beneath the succession suggests acidic, sulfur-rich hydrothermal activity may have interacted with the silicified sediments of the Strelley Pool Chert.

Portable concealed weapon detection using millimeter-wave FMCW radar imaging

NASA Astrophysics Data System (ADS)

Johnson, Michael A.; Chang, Yu-Wen

2001-02-01

Unobtrusive detection of concealed weapons on persons or in abandoned bags would provide law enforcement a powerful tool to focus resources and increase traffic throughput in high- risk situations. We have developed a fast image scanning 94 GHz radar system that is suitable for portable operation and remote viewing of radar data. This system includes a novel fast image-scanning antenna that allows for the acquisition of medium resolution 3D millimeter wave images of stationary targets with frame times on order of one second. The 3D radar data allows for potential isolation of concealed weapons from body and environmental clutter such as nearby furniture or other people. The radar is an active system so image quality is not affected indoors, emitted power is however very low so there are no health concerns for operator or targets. The low power operation is still sufficient to penetrate heavy clothing or material. Small system size allows for easy transport and rapid deployment of the system as well as an easy migration path to future hand held systems.

On the pressure field of nonlinear standing water waves

NASA Technical Reports Server (NTRS)

Schwartz, L. W.

1980-01-01

The pressure field produced by two dimensional nonlinear time and space periodic standing waves was calculated as a series expansion in the wave height. The high order series was summed by the use of Pade approximants. Calculations included the pressure variation at great depth, which was considered to be a likely cause of microseismic activity, and the pressure distribution on a vertical barrier or breakwater.

Ophthalmodynamometry for ICP prediction and pilot test on Mt. Everest.

PubMed

Querfurth, Henry W; Lieberman, Philip; Arms, Steve; Mundell, Steve; Bennett, Michael; van Horne, Craig

2010-11-01

A recent development in non-invasive techniques to predict intracranial pressure (ICP) termed venous ophthalmodynamometry (vODM) has made measurements in absolute units possible. However, there has been little progress to show utility in the clinic or field. One important application would be to predict changes in actual ICP during adaptive responses to physiologic stress such as hypoxia. A causal relationship between raised intracranial pressure and acute mountain sickness (AMS) is suspected. Several MRI studies report that modest physiologic increases in cerebral volume, from swelling, normally accompany subacute ascent to simulated high altitudes. 1) Validate and calibrate an advanced, portable vODM instrument on intensive patients with raised intracranial pressure and 2) make pilot, non-invasive ICP estimations of normal subjects at increasing altitudes. The vODM was calibrated against actual ICP in 12 neurosurgical patients, most affected with acute hydrocephalus and monitored using ventriculostomy/pressure transducers. The operator was blinded to the transducer read-out. A clinical field test was then conducted on a variable data set of 42 volunteer trekkers and climbers scaling Mt. Everest, Nepal. Mean ICPs were estimated at several altitudes on the ascent both across and within subjects. Portable vODM measurements increased directly and linearly with ICP resulting in good predictability (r = 0.85). We also found that estimated ICP increases normally with altitude (10 ± 3 mm Hg; sea level to 20 ± 2 mm Hg; 6553 m) and that AMS symptoms did not correlate with raised ICP. vODM technology has potential to reliably estimate absolute ICP and is portable. Physiologic increases in ICP and mild-mod AMS are separate responses to high altitude, possibly reflecting swelling and vasoactive instability, respectively.

Instruments and attachments for electronystagmography

NASA Technical Reports Server (NTRS)

Mironenko, Y. T.; Vilenskiy, A. A.

1980-01-01

A portable set of instruments and devices was developed which makes it possible to record spontaneous nystagmus with open and closed eyes. Rotational, caloric, position, and pressure nystagmus under any conditions may also be recorded.

9. RW Meyer Sugar Mill: 18761889. Locomotivetype, firetube, portable boiler, ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

9. RW Meyer Sugar Mill: 1876-1889. Locomotive-type, fire-tube, portable boiler, No. 1 model. Manufactured by Ames Iron Works, Oswego, New York, 1879. 120 lbs/sq. inch working pressure, 66 sq. ft. heating surface in tubes. View: from side. The boiler provided steam for steam engine which in turn powered the mill's centrifugals. The section on the left side included the firebox with its surrounding water-legs. The fluted chimney-type structure is the steam port, safety valve, and whistle. Column projecting from side was part of steam pressure and water gauge. Pipe running above boiler carried steam to the engine. Pipe running below boiler provided the boiler feed-water. Cylindrical section included 22 fire-tube surrounded by water. The far right ... - R. W. Meyer Sugar Mill, State Route 47, Kualapuu, Maui County, HI

Six components observations of local earthquakes during the 2016 Central Italy seismic sequence

NASA Astrophysics Data System (ADS)

Simonelli, A.; Bernauer, F.; Chow, B.; Braun, T.; Wassermann, J. M.; Igel, H.

2017-12-01

For many years the seismological community has looked for a reliable, sensitive, broadband three-component portable rotational sensor. In this preliminary study, we show the possibility of measuring and extracting relevant seismological information from local earthquakes. We employ portable three-component rotational sensors, insensitive to translations, which operate on optical interferometry principles (Sagnac effect). Multiple sensors recording redundantly add significance to the measurements.During the Central Italy seismic sequence in November 2016, we deployed two portable fiber-optic gyroscopes (BlueSeis3A from iXBlue and LCG demonstrator from LITEF) and a broadband seismometer in Colfiorito, Italy. We present here the six-component observations, with analysis of rotational (three redundant components) and translational (three components) ground motions, generated by earthquakes at local distances. For each seismic event, we compare coherence between rotational sensors and estimate a back azimuth consistent with theoretical values. We also estimate Love and Rayleigh wave phase velocities in the 5 to 10 Hz frequency range.

Methods and apparatus for moving and separating materials exhibiting different physical properties

DOEpatents

Peterson, Stephen C.; Brimhall, Owen D.; McLaughlin, Thomas J.; Baker, Charles D.; Sparks, Sam L.

1991-01-01

Methods and apparatus for controlling the movement of materials having different physical properties when one of the materials is a fluid. The invention does not rely on flocculation, sedimentation, centrifugation, the buoyancy of the materials, or any other gravity dependent characteristic, in order to achieve its desired results. The methods of the present invention provide that a first acoustic wave is propagated through a vessel containing the materials. A second acoustic wave, at a frequency different than the first acoustic wave, is also propagated through the vessel so that the two acoustic waves are superimposed upon each other. The superimposition of the two waves creates a beat frequency wave. The beat frequency wave comprises pressure gradients dividing regions of maximum and minimum pressure. The pressure gradients and the regions of maximum and minimum pressure move through space and time at a group velocity. The moving pressure gradients and regions of maximum and minimum pressure act upon the materials so as to move one of the materials towards a predetermined location in the vessel. The present invention provides that the materials may be controllably moved toward a location, aggregated at a particular location, or physically separated from each other.

Methods and apparatus for moving and separating materials exhibiting different physical properties

DOEpatents

Peterson, Stephen C.; Brimhall, Owen D.; McLaughlin, Thomas J.; Baker, Charles D.; Sparks, Sam L.

1988-01-01

Methods and apparatus for controlling the movement of materials having different physical properties when one of the materials is a fluid. The invention does not rely on flocculation, sedimentation, centrifugation, the buoyancy of the materials, or any other gravity dependent characteristic, in order to achieve its desired results. The methods of the present invention provide that a first acoustic wave is progpagated through a vessel containing the materials. A second acoustic wave, at a frequency different than the first acoustic wave, is also propagated through the vessel so that the two acoustic waves are superimposed upon each other. The superimposition of the two waves creates a beat frequency wave. The beat frequency wave comprises pressure gradients dividing regions of maximum and minimum pressure. The pressure gradients and the regions of maximum and minimum pressure move through space and time at a group velocity. The moving pressure gradients and regions of maximum and minimum pressure act upon the marterials so as to move one of the materials towards a predetermined location in the vessel. The present invention provides that the materials may be controllably moved toward a location, aggreated at a particular location, or physically separated from each other.

Development of UV Optical Measurements of Nitric Oxide and Hydroxyl Radical at the Exit of High Pressure Gas Turbine Combustors

NASA Technical Reports Server (NTRS)

Liscinsky, D. S.; Knight, B. A.; Shirley, J. A.

1998-01-01

Measurements of nitric oxide (NO) and hydroxyl radical (OR) have been made in a laboratory flat flame at pressures up to 30 atm using line-of-sight resonant absorption. Data are reported at equivalence ratios of 0.98 and 1.3 and pressures of 1, 5, 10, 20 and 30 atm. The performance of the in-situ LTV absorption technique with assessed at these elevated pressures by comparing the measured absorption with those predicted by detailed theoretical spectroscopic models for NO and OH. Previous to this experiment the resonant models had not been verified at pressures greater than two atmospheres. Agreement within 25% was found between the measurements and predictions with only slight modification of the existing models for both NO and OH to account for line center shifting and pressure broadening. Continuum interference of hot oxygen (O2) on the NO absorption spectra was not significant in the interpretation of the data. The optical methods used in this study are distinct from laser-based diagnostics such as laser induced fluorescence and, hence, have the potential to provide independent verification of the laser-based measurements. The methodology is also of sufficient simplicity to be hardened into a portable optical measurement system that can be deployed in gas turbine engine test cells. A miniature fiber optic couple portable instrument is described.

Analysis of Measured and Simulated Supraglottal Acoustic Waves.

PubMed

Fraile, Rubén; Evdokimova, Vera V; Evgrafova, Karina V; Godino-Llorente, Juan I; Skrelin, Pavel A

2016-09-01

To date, although much attention has been paid to the estimation and modeling of the voice source (ie, the glottal airflow volume velocity), the measurement and characterization of the supraglottal pressure wave have been much less studied. Some previous results have unveiled that the supraglottal pressure wave has some spectral resonances similar to those of the voice pressure wave. This makes the supraglottal wave partially intelligible. Although the explanation for such effect seems to be clearly related to the reflected pressure wave traveling upstream along the vocal tract, the influence that nonlinear source-filter interaction has on it is not as clear. This article provides an insight into this issue by comparing the acoustic analyses of measured and simulated supraglottal and voice waves. Simulations have been performed using a high-dimensional discrete vocal fold model. Results of such comparative analysis indicate that spectral resonances in the supraglottal wave are mainly caused by the regressive pressure wave that travels upstream along the vocal tract and not by source-tract interaction. On the contrary and according to simulation results, source-tract interaction has a role in the loss of intelligibility that happens in the supraglottal wave with respect to the voice wave. This loss of intelligibility mainly corresponds to spectral differences for frequencies above 1500 Hz. Copyright © 2016 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

Maps and geospatial data for the Shorty’s Island and Myrtle Bend substrate enhancement pilot projects, Kootenai River near Bonners Ferry, Idaho, 2014

USGS Publications Warehouse

Fosness, Ryan L.

2014-01-01

This report presents the methods used to develop georeferenced portable document format maps and geospatial data that describe spawning locations and physical habitat characteristics (including egg mat locations, bathymetry, surficial sediment facies, and streamflow velocity) within the substrate enhancement pilot project study area. The results are presented as two maps illustrating the physical habitat characteristics along with proposed habitat enhancement areas, aerial imagery, and hydrography. The results of this study will assist researchers, policy makers, and management agencies in deciding the spatial location and extent of the substrate enhancement pilot project.

Space weather effects on lower ionosphere: First investigation from Bharati station during 34th Indian scientific expedition to Antarctica

NASA Astrophysics Data System (ADS)

Guha, Anirban; Saha, Kumarjit; De, Barin Kumar; Subrahmanyam, Kandula Venkata; Shreedevi, P. R.

2017-04-01

We investigate the solar flare effects on the D-region of the ionosphere with the help of VLF (Very Low Frequency) radio waves using a portable E-field system from Antarctica during the summer period of 34th Indian scientific expedition. Two GPS time synchronized VLF receivers, one located at Bharati, Antarctica (geographical latitude 69.40°S, longitude 76.18°E) and another located at Tripura, India (geographical latitude 23.84°N, longitude 91.28°E) were operated simultaneously to infer common mode changes in the lower ionosphere for a number of solar flares events. The two systems constantly monitored the carrier amplitude and phase of the MSK (Minimum Shift Keying) modulated navy transmitter located in Australia (Callsign: NWC, 19.8 kHz, geographical latitude 21.88°S, longitude 114.13°E), around 5.6 Mm great circle distance from the two receivers. The results are interpreted in terms of Earth-ionosphere wave-guide characteristics. A Long Wave Propagation Capability (LWPC) model study is also performed to infer the changes in the daytime electron density in polar D-region ionosphere during the solar flares. The exponential fit of the modeled electron density change with average X-ray flux change shows an excellent correlation (R2 value 0.95). The exponential fit is utilized to infer the daytime electron density change in the polar ionosphere during solar flare events. The analyses indicate that small solar flares of class 'C' can be very effectively detected with the portable antenna system even if the receiver is located in polar coastal region compared to equatorial region. The expedition results also demonstrate the feasibility of using portable VLF receivers from the coastal stations for monitoring the polar lower ionosphere from Antarctica and open up new opportunities for long term exploration.

Development Of A Numerical Tow Tank With Wave Generation To Supplement Experimental Efforts

DTIC Science & Technology

2017-12-01

vehicles CAD computer aided design CFD computational fluid dynamics FVM finite volume method IO information operations ISR intelligence, surveillance, and...deliver a product that I am truly proud of. xv THIS PAGE INTENTIONALLY LEFT BLANK xvi CHAPTER 1: Introduction 1.1 Importance of Tow Tank Testing Modern...wedge installation. 1 In 2016, NPS student Ensign Ryan Tran adapted an existing vertical plunging wedge wave maker design used at the U.S. Naval

The Timer-Logger-Communicator for Continuous, Mobile Measurement of Wheelchair Pressure Reliefs

PubMed Central

Grip, Jeffrey C.; Merbitz, Charles T.

1985-01-01

A recently developed device which provides continuous, direct monitoring of the pressure-relief performance of persons confined to wheelchairs is reported. A custom portable computer records the data, which is transferred for analysis to an Apple IIe. The mobile computer can also signal the patient to relieve pressure based on preset criteria and the patient's performance. Teaching lift-offs to prevent ischial pressure sores is the object. Data collected with the device are used clinically and for research. Examples of such data are presented. The benefits of the device are reviewed.

Experimental study on the pressure and pulse wave propagation in viscoelastic vessel tubes-effects of liquid viscosity and tube stiffness.

PubMed

Ikenaga, Yuki; Nishi, Shohei; Komagata, Yuka; Saito, Masashi; Lagrée, Pierre-Yves; Asada, Takaaki; Matsukawa, Mami

2013-11-01

A pulse wave is the displacement wave which arises because of ejection of blood from the heart and reflection at vascular bed and distal point. The investigation of pressure waves leads to understanding the propagation characteristics of a pulse wave. To investigate the pulse wave behavior, an experimental study was performed using an artificial polymer tube and viscous liquid. A polyurethane tube and glycerin solution were used to simulate a blood vessel and blood, respectively. In the case of the 40 wt% glycerin solution, which corresponds to the viscosity of ordinary blood, the attenuation coefficient of a pressure wave in the tube decreased from 4.3 to 1.6 dB/m because of the tube stiffness (Young's modulus: 60 to 200 kPa). When the viscosity of liquid increased from approximately 4 to 10 mPa·s (the range of human blood viscosity) in the stiff tube, the attenuation coefficient of the pressure wave changed from 1.6 to 3.2 dB/m. The hardening of the blood vessel caused by aging and the increase of blood viscosity caused by illness possibly have opposite effects on the intravascular pressure wave. The effect of the viscosity of a liquid on the amplitude of a pressure wave was then considered using a phantom simulating human blood vessels. As a result, in the typical range of blood viscosity, the amplitude ratio of the waves obtained by the experiments with water and glycerin solution became 1:0.83. In comparison with clinical data, this value is much smaller than that seen from blood vessel hardening. Thus, it can be concluded that the blood viscosity seldom affects the attenuation of a pulse wave.

Compressional ULF waves in the outer magnetosphere. 2: A case study of Pc 5 type wave activity

NASA Technical Reports Server (NTRS)

Zhu, Xiaoming; Kivelson, Margaret G.

1994-01-01

In previously published work (Zhu and Kivelson, 1991) the spatial distribution of compressional magnetic pulsations of period 2 - 20 min in the outer magnetosphere was described. In this companion paper, we study some specific compressional events within our data set, seeking to determine the structure of the waves and identifying the wave generation mechanism. We use both the magnetic field and three-dimensional plasma data observed by the International Sun-Earth Explorer (ISEE) 1 and/or 2 spacecraft to characterize eight compressional ultra low frequency (ULF) wave events with frequencies below 8 mHz in the outer magnetosphere. High time resolution plasma data for the event of July 24, 1978, made possible a detailed analysis of the waves. Wave properties specific to the event of July 24, 1978, can be summarized as follows: (1) Partial plasma pressures in the different energy ranges responded to the magnetic field pressure differently. In the low-energy range they oscillated in phase with the magnetic pressure, while oscillations in higher-energy ranges were out-of-phase; (2) Perpendicular wavelengths for the event were determined to be 60,000 and 30,000 km in the radial and azimuthal directions, respectively. Wave properties common to all events can be summarized as follows: (1) Compressional Pc 5 wave activity is correlated with Beta, the ratio of the plasma pressure to the magnetic pressure; the absolute magnitude of the plasma pressure plays a minor role for the wave activity; (2) The magnetic equator is a node of the compressional perturbation of the magnetic field; (3) The criterion for the mirror mode instability is often satisfied near the equator in the outer magnetosphere when the compressional waves are present. We believe these waves are generated by internal magnetohydrodynamic (MHD) instabilities.

Particle image velocimetry investigation of a finite amplitude pressure wave

NASA Astrophysics Data System (ADS)

Thornhill, D.; Currie, T.; Fleck, R.; Chatfield, G.

2006-03-01

Particle image velocimetry is used to study the motion of gas within a duct subject to the passage of a finite amplitude pressure wave. The wave is representative of the pressure waves found in the exhaust systems of internal combustion engines. Gas particles are accelerated from stationary to 150 m/s and then back to stationary in 8 ms. It is demonstrated that gas particles at the head of the wave travel at the same velocity across the duct cross section at a given point in time. Towards the tail of the wave viscous effects are plainly evident causing the flow profile to tend towards parabolic. However, the instantaneous mean particle velocity across the section is shown to match well with the velocity calculated from a corresponding measured pressure history using 1D gas dynamic theory. The measured pressure history at a point in the duct was acquired using a high speed pressure transducer of the type typically used for engine research in intake and exhaust systems. It is demonstrated that these are unable to follow the rapid changes in pressure accurately and that they are prone to resonate under certain circumstances.

Novel device (AirWave) to assess endotracheal tube migration: a pilot study.

PubMed

Nacheli, Gustavo Cumbo; Sharma, Manish; Wang, Xiaofeng; Gupta, Amit; Guzman, Jorge A; Tonelli, Adriano R

2013-08-01

Little is known about endotracheal tube (ETT) migration during routine care among critically ill patients. AirWave is a novel device that uses sonar waves to measure ETT migration and obstructions in real time. The aim of the present study is to assess the accuracy of the AirWave to evaluate ETT migration. In addition, we determined the degree of variation in ETT position and tested whether more pronounced migration occurs in specific clinical scenarios. After institutional review board approval, we included mechanically ventilated patients from February 2012 to May 2012. A chest radiography (CXR) was obtained at baseline and 24 hours when clinically indicated. The ETT distance at the lips was recorded at baseline and every 4 hours. The AirWave system continuously recorded ETT position changes from baseline, and luminal obstructions. A total of 42 patients (age: 61 [SD ±13] years, men: 52%) were recruited. A total of 19 patients had measurements of ETT migration at 24 hours by the 3 methodologies used in this study. The mean (SD) of the ETT migration at 24 hours was +0.04 (1.2), -0.42 (0.7) and +0.34 (1.81) cm when measured by portable CXR, ETT distance at the teeth and AirWave device, respectively. Bland-Altman analysis of tube migration at 24 hours comparing the AirWave with CXR readings showed a bias of 0.1 cm with 95% limit of agreement of -3.8 and +4.3 cm. Comparison of tube migration at 24 hours determined by AirWave with ETT distance at the lips revealed a bias of -0.4 with 95% limit of agreement -3.7 to +3 cm, similar to the values observed between CXR and ETT distance at the lips (bias of -0.3 cm, 95% limit of agreement of -3.4 to +2.8 cm). Factors associated with ETT migration at 24 hours were ETT size and initial measurement from ETT tip to carina by portable CXR. AirWave detected in eight patients some degree of ETT obstruction (30% ± 9.6%) that resolved with prompt ETT catheter suction. The AirWave may provide useful information regarding ETT migration and obstruction in real time. Copyright © 2013 Elsevier Inc. All rights reserved.

Wave data processing toolbox manual

USGS Publications Warehouse

Sullivan, Charlene M.; Warner, John C.; Martini, Marinna A.; Lightsom, Frances S.; Voulgaris, George; Work, Paul

2006-01-01

Researchers routinely deploy oceanographic equipment in estuaries, coastal nearshore environments, and shelf settings. These deployments usually include tripod-mounted instruments to measure a suite of physical parameters such as currents, waves, and pressure. Instruments such as the RD Instruments Acoustic Doppler Current Profiler (ADCP(tm)), the Sontek Argonaut, and the Nortek Aquadopp(tm) Profiler (AP) can measure these parameters. The data from these instruments must be processed using proprietary software unique to each instrument to convert measurements to real physical values. These processed files are then available for dissemination and scientific evaluation. For example, the proprietary processing program used to process data from the RD Instruments ADCP for wave information is called WavesMon. Depending on the length of the deployment, WavesMon will typically produce thousands of processed data files. These files are difficult to archive and further analysis of the data becomes cumbersome. More imperative is that these files alone do not include sufficient information pertinent to that deployment (metadata), which could hinder future scientific interpretation. This open-file report describes a toolbox developed to compile, archive, and disseminate the processed wave measurement data from an RD Instruments ADCP, a Sontek Argonaut, or a Nortek AP. This toolbox will be referred to as the Wave Data Processing Toolbox. The Wave Data Processing Toolbox congregates the processed files output from the proprietary software into two NetCDF files: one file contains the statistics of the burst data and the other file contains the raw burst data (additional details described below). One important advantage of this toolbox is that it converts the data into NetCDF format. Data in NetCDF format is easy to disseminate, is portable to any computer platform, and is viewable with public-domain freely-available software. Another important advantage is that a metadata structure is embedded with the data to document pertinent information regarding the deployment and the parameters used to process the data. Using this format ensures that the relevant information about how the data was collected and converted to physical units is maintained with the actual data. EPIC-standard variable names have been utilized where appropriate. These standards, developed by the NOAA Pacific Marine Environmental Laboratory (PMEL) (http://www.pmel.noaa.gov/epic/), provide a universal vernacular allowing researchers to share data without translation.

Spatial patterns of fasting and fed antropyloric pressure waves in humans.

PubMed Central

Sun, W M; Hebbard, G S; Malbert, C H; Jones, K L; Doran, S; Horowitz, M; Dent, J

1997-01-01

1. Gastric mechanics were investigated by categorizing the temporal and spatial patterning of pressure waves associated with individual gastric contractions. 2. In twelve healthy volunteers, intraluminal pressures were monitored from nine side hole recording points spaced at 1.5 cm intervals along the antrum, pylorus and duodenum. 3. Pressure wave sequences that occurred during phase II fasting contractions (n = 221) and after food (n = 778) were evaluated. 4. The most common pattern of pressure wave onset along the antrum was a variable combination of antegrade, synchronous and retrograde propagation between side hole pairs. This variable pattern accounted for 42% of sequences after food, and 34% during fasting (P < 0.05). Other common pressure wave sequence patterns were: purely antegrade-29% after food and 42% during fasting (P < 0.05); purely synchronous-23% fed and 17% fasting; and purely retrograde-6% fed and 8% fasting. The length of sequences was shorter after food (P < 0.05). Some sequences 'skipped' individual recording points. 5. The spatial patterning of gastric pressure wave sequences is diverse, and may explain the differing mechanical outcomes among individual gastric contractions. 6. Better understanding of gastric mechanics may be gained from temporally precise correlations of luminal flows and pressures and gastric wall motion during individual gastric contraction sequences. PMID:9306286

Plant moisture stress: a portable freezing-point meter compared with the psychrometer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cary, J.W.; Fisher, H.D.

A small portable instrument for measuring the freezing-point depression of plant tissue has been developed for field use. The instrument is easy to operate and can be constructed from materials costing less than $100. Moisture stress measurements made with the freezing-point meter on a variety of plants were compared with vapor pressure psychrometer measurements. Variation between duplicates in the freezing point averaged 1.2 bars, but differences between stress measurements made with the psychrometer and freezing-point instrument averaged 2.6 bars. 11 references, 5 figures, 2 tables.

Plateau Waves of Intracranial Pressure and Partial Pressure of Cerebral Oxygen.

PubMed

Lang, Erhard W; Kasprowicz, Magdalena; Smielewski, Peter; Pickard, John; Czosnyka, Marek

2016-01-01

This study investigates 55 intracranial pressure (ICP) plateau waves recorded in 20 patients after severe traumatic brain injury (TBI) with a focus on a moving correlation coefficient between mean arterial pressure (ABP) and ICP, called PRx, which serves as a marker of cerebrovascular reactivity, and a moving correlation coefficient between ABP and cerebral partial pressure of oxygen (pbtO2), called ORx, which serves as a marker for cerebral oxygen reactivity. ICP and ICPamplitude increased significantly during the plateau waves, whereas CPP and pbtO2 decreased significantly. ABP, ABP amplitude, and heart rate remained unchanged. In 73 % of plateau waves PRx increased during the wave. ORx showed an increase during and a decrease after the plateau waves, which was not statistically significant. Our data show profound cerebral vasoparalysis on top of the wave and, to a lesser extent, impairment of cerebral oxygen reactivity. The different behavior of the indices may be due to the different latencies of the cerebral blood flow and oxygen level control mechanisms. While cerebrovascular reactivity is a rapidly reacting mechanism, cerebral oxygen reactivity is slower.

On propagation of axisymmetric waves in pressurized functionally graded elastomeric hollow cylinders

NASA Astrophysics Data System (ADS)

Wu, Bin; Su, Yipin; Liu, Dongying; Chen, Weiqiu; Zhang, Chuanzeng

2018-05-01

Soft materials can be designed with a functionally graded (FG) property for specific applications. Such material inhomogeneity can also be found in many soft biological tissues whose functionality is only partly understood to date. In this paper, we analyze the axisymmetric guided wave propagation in a pressurized FG elastomeric hollow cylinder. The cylinder is subjected to a combined action of axial pre-stretch and pressure difference applied to the inner and outer cylindrical surfaces. We consider both torsional waves and longitudinal waves propagating in the FG cylinder made of incompressible isotropic elastomer, which is characterized by the Mooney-Rivlin strain energy function but with the material parameters varying with the radial coordinate in an affine way. The pressure difference generates an inhomogeneous deformation field in the FG cylinder, which dramatically complicates the superimposed wave problem described by the small-on-large theory. A particularly efficient approach is hence employed which combines the state-space formalism for the incremental wave motion with the approximate laminate or multi-layer technique. Dispersion relations for the two types of axisymmetric guided waves are then derived analytically. The accuracy and convergence of the proposed approach is validated numerically. The effects of the pressure difference, material gradient, and axial pre-stretch on both the torsional and the longitudinal wave propagation characteristics are discussed in detail through numerical examples. It is found that the frequency of axisymmetric waves depends nonlinearly on the pressure difference and the material gradient, and an increase in the material gradient enhances the capability of the pressure difference to adjust the wave behavior in the FG cylinder. This work provides a theoretical guidance for characterizing FG soft materials by in-situ ultrasonic nondestructive evaluation and for designing tunable waveguides via material tailoring along with an adjustment of the pre-stretch and pressure difference.

Cardiac output in idiopathic normal pressure hydrocephalus: association with arterial blood pressure and intracranial pressure wave amplitudes and outcome of shunt surgery

PubMed Central

2011-01-01

Background In patients with idiopathic normal pressure hydrocephalus (iNPH) responding to shunt surgery, we have consistently found elevated intracranial pressure (ICP) wave amplitudes during diagnostic ICP monitoring prior to surgery. It remains unknown why ICP wave amplitudes are increased in these patients. Since iNPH is accompanied by a high incidence of vascular co-morbidity, a possible explanation is that there is reduced vascular compliance accompanied by elevated arterial blood pressure (ABP) wave amplitudes and even altered cardiac output (CO). To investigate this possibility, the present study was undertaken to continuously monitor CO to determine if it is correlated to ABP and ICP wave amplitudes and the outcome of shunting in iNPH patients. It was specifically addressed whether the increased ICP wave amplitudes seen in iNPH shunt responders were accompanied by elevated CO and/or ABP wave amplitude levels. Methods Prospective iNPH patients (29) were clinically graded using an NPH grading scale. Continuous overnight minimally-invasive monitoring of CO and ABP was done simultaneously with ICP monitoring; the CO, ABP, and ICP parameters were parsed into 6-second time windows. Patients were assessed for shunt surgery on clinical grade, Evan's index, and ICP wave amplitude. Follow-up clinical grading was performed 12 months after surgery. Results ICP wave amplitudes but not CO or ABP wave amplitude, showed good correlation with the response to shunt treatment. The patients with high ICP wave amplitude did not have accompanying high levels of CO or ABP wave amplitude. Correlation analysis between CO and ICP wave amplitudes in individual patients showed different profiles [significantly positive in 10 (35%) and significantly negative in 16 (55%) of 29 recordings]. This depended on whether there was also a correlation between ABP and ICP wave amplitudes and on the average level of ICP wave amplitude. Conclusions These results gave no evidence that the increased levels of ICP wave amplitudes seen in iNPH shunt responders prior to surgery were accompanied by elevated levels of ABP wave amplitudes or elevated CO. In the individual patients the correlation between CO and ICP wave amplitude was partly related to an association between ABP and ICP wave amplitudes which can be indicative of the state of cerebrovascular pressure regulation, and partly related to the ICP wave amplitude which can be indicative of the intracranial compliance. PMID:21349148

Experimental observation of standing interfacial waves induced by surface waves in muddy water

NASA Astrophysics Data System (ADS)

Maxeiner, Eric; Dalrymple, Robert A.

2011-09-01

A striking feature has been observed in a laboratory wave tank with a thin layer of clear water overlying a layer of mud. A piston-type wave maker is used to generate long monochromatic surface waves in a tank with a layer of kaolinite clay at the bottom. The wave action on the mud causes the clay particles to rise from the bottom into the water column, forming a lutocline. As the lutocline approaches the water surface, a set of standing interfacial waves form on the lutocline. The interfacial wave directions are oriented nearly orthogonal to the surface wave direction. The interfacial waves, which sometimes cover the entire length and width of the tank, are also temporally subharmonic as the phase of the interfacial wave alternates with each passing surface wave crest. These interfacial waves are the result of a resonant three-wave interaction involving the surface wave train and the two interfacial wave trains. The interfacial waves are only present when the lutocline is about 3 cm of the water surface and they can be sufficiently nonlinear as to exhibit superharmonics and a breaking-type of instability.

49 CFR 178.274 - Specifications for UN portable tanks.

Code of Federal Regulations, 2014 CFR

2014-10-01

... welding of pressure vessels. When the manufacturing process or the materials make it necessary, the shells... strength of the tubing, such as may happen when cutting threads. Brazed joints are not authorized for...

49 CFR 178.274 - Specifications for UN portable tanks.

Code of Federal Regulations, 2012 CFR

2012-10-01

... welding of pressure vessels. When the manufacturing process or the materials make it necessary, the shells... strength of the tubing, such as may happen when cutting threads. Brazed joints are not authorized for...

Characterization and Performance of a Liquid Hydrocarbon-Fueled Pulse Detonation Rocket Engine

DTIC Science & Technology

2001-12-01

head wall pressure (P3) and the two sensors at the end of the tube provided indication of detonation wave passage (Wave1 and Wave2 ). These data...wave speed using the time of passage at Wave1 and Wave2 and the user-defined value of the distance between each sensor (this distance varied slightly...for each tube extension). A detonation velocity of zero was returned for any event in which neither Wave1 or Wave2 sensed a pressure rise of

Effect of pressurization on helical guided wave energy velocity in fluid-filled pipes.

PubMed

Dubuc, Brennan; Ebrahimkhanlou, Arvin; Salamone, Salvatore

2017-03-01

The effect of pressurization stresses on helical guided waves in a thin-walled fluid-filled pipe is studied by modeling leaky Lamb waves in a stressed plate bordered by fluid. Fluid pressurization produces hoop and longitudinal stresses in a thin-walled pipe, which corresponds to biaxial in-plane stress in a plate waveguide model. The effect of stress on guided wave propagation is accounted for through nonlinear elasticity and finite deformation theory. Emphasis is placed on the stress dependence of the energy velocity of the guided wave modes. For this purpose, an expression for the energy velocity of leaky Lamb waves in a stressed plate is derived. Theoretical results are presented for the mode, frequency, and directional dependent variations in energy velocity with respect to stress. An experimental setup is designed for measuring variations in helical wave energy velocity in a thin-walled water-filled steel pipe at different levels of pressure. Good agreement is achieved between the experimental variations in energy velocity for the helical guided waves and the theoretical leaky Lamb wave solutions. Copyright © 2016 Elsevier B.V. All rights reserved.

Investigation of wave phenomena on a blunt airfoil with straight and serrated trailing edges

NASA Astrophysics Data System (ADS)

Nies, Juliane M.; Gageik, Manuel A.; Klioutchnikov, Igor; Olivier, Herbert

2015-07-01

An investigation of pressure waves in compressible subsonic and transonic flow around a generic airfoil is performed in a modified shock tube. New comprehensive results are presented on pressure waves in compressible flow. For the first time, the influence of trailing edge serration will be examined in terms of the reduction in pressure wave amplitude. A generic airfoil is tested in two main configurations, one with blunt trailing edges and the other one with serrated trailing edges in a Mach number range from 0.6 to 0.8 and at chord Reynolds numbers of 1 × 106 < Re c < 5 ×106. The flow of the blunt trailing edge is characterized by a regular vortex street in the wake creating a regular pattern of upstream-moving pressure waves along the airfoil. The observed pressure waves lead to strong pressure fluctuations within the local flow field. A reduction in the trailing edge thickness leads to a proportional increase in the frequency of the vortex street in the wake as well as the frequency of the waves deduced from constant Strouhal number. By serrating the trailing edge, the formation of vortices in the wake is disturbed. Therefore, also the upstream-moving waves are influenced and reduced in their strength resulting in a steadier flow. An increasing length of the saw tooth enhances the three dimensionality of the structures in the wake and causes a strong decrease in the wave amplitude.

Stress wave riveting. [of aircraft metal skin

NASA Technical Reports Server (NTRS)

Leftheris, B. P.

1972-01-01

The stress wave riveter deforms the rivet material by a high amplitude stress wave. Thus, the entire rivet is set in motion radially. The rivet expands rapidly and impacts the hole surface before the rivet tail begins to form. Unlike the oversqueezed rivets, therefore, it sets up uniform interference without distortion in the skins. Furthermore, the radial velocity is so high (over 200 in./sec) that upon impact with the hole surface it deforms the surface plastically. This is especially effective in aluminum skins. Thus the SWR combines the advantages of plastically deforming the hole and the economic advantage of a relatively nonprecision hole and inexpensive rivets like those used in oversqueezing. The additional advantage SWR offers is that it is a portable tool.

Increased aortic wave reflection contributes to higher systolic blood pressure in adolescents born preterm.

PubMed

Kowalski, Remi R; Beare, Richard; Mynard, Jonathan P; Cheong, Jeanie L Y; Doyle, Lex W; Smolich, Joseph J; Cheung, Michael M H

2018-03-29

To evaluate the wave reflection characteristics in the aortic arch and common carotid artery of ex-preterm adolescents and assess their relationship to central blood pressure in a cohort followed prospectively since birth. Central blood pressures, pulse wave velocity, augmentation index, microvascular reactive hyperemia, arterial distensibility, compliance and stiffness index, and also aortic and carotid wave intensity were measured in 18-year-olds born extremely preterm at below 28 weeks' gestation (n = 76) and term-born controls (n = 42). Compared with controls, ex-preterm adolescents had higher central systolic (111 ± 11 vs. 105 ± 10 mmHg; P < 0.001) and diastolic blood pressures (73 ± 7 vs. 67 ± 7 mmHg; P < 0.001). Although conventional measures of arterial function and biomechanics such as pulse wave velocity and augmentation index were no different between groups, wave intensity analysis revealed elevated backward compression wave area (-0.39 ± 0.21 vs. -0.29 ± 0.17 W/m/s × 10; P = 0.03), backward compression wave pressure change (9.0 ± 3.5 vs. 6.6 ± 2.5 mmHg; P = 0.001) and reflection index (0.44 ± 0.15 vs. 0.32 ± 0.08; P < 0.001) in the aorta of ex-preterm adolescents compared with controls. These changes were less pronounced in the carotid artery. On multivariable analysis, forward and backward compression wave areas were the only biomechanical variables associated with central systolic pressure. Ex-preterm adolescents demonstrate elevated wave reflection indices in the aortic arch, which correlate with central systolic pressure. Wave intensity analysis may provide a sensitive novel marker of evolving vascular dysfunction in ex-preterm survivors.

The stability of arterial blood gases during transportation of patients using the RespirTech PRO.

PubMed

Romano, M; Raabe, O G; Walby, W; Albertson, T E

2000-05-01

The transportation of critically ill patients requiring mechanical ventilation is recognized as a high-risk and expensive procedure. Approaches have included using manual bag-type valve resuscitators and expensive portable transport ventilators. This study evaluated the effectiveness of the inexpensive portable RespirTech PRO (RTP) gas-powered automatic resuscitator during intrahospital transport of critically ill mechanically ventilated patients. Twenty medical intensive care patients on stable mechanical ventilator settings had arterial blood gas and vital sign determination before routine transport out of the intensive care unit (ICU). Repeat measurements were made during transport approximately 30 minutes after being placed on the RTP portable pressure-cycled automatic resuscitator using an FiO2 of 100%. During use of the RTP for transport, there were no statistically significant variations observed in mean arterial blood pressure [82 +/- 11 SD (range 65 to 112) mm Hg before transport versus 85 +/- 14 SD (range 59 to 110) mm Hg during transport], heart rate [94 +/- 16 SD (range 74 to 127) beats/min) before versus 96 +/- 17 SD (range 69 to 132) beats/min during], arterial pH [7.41 +/- 0.07 SD (range 7.31 to 7.58) before versus 7.42 +/- 0.05 SD (range 7.37 to 7.52) during], and PaCO2 [43 +/- 10 SD (range 26 to 65) mm Hg before versus 43 +/- 10 SD (range 27 to 61 mm Hg) during]. Because the FiO2 before transport was 63 +/- 26 SD (range 30% to 100%) versus 100% during transport using the RTP, the mean PaO2 was significantly increased from 124 +/- 86 SD (range 57 to 367) mm Hg before transport to 297 +/- 168 SD (range 65 to 537) mm Hg during (P< .001). No transportation associated clinical adverse events were noted. Several previous investigations have shown that portable ventilators are safe and effective in intrahospital transport of mechanically ventilated patients. This study showed that the portable pressure-cycled RTP also allows safe transportation of mechanically ventilated ICU patients. By analogy, the RTP is potentially useful as an automatic resuscitator for emergency medical care. This RTP is a disposable resuscitator/ventilator device that provides an inexpensive alternative for transporting ventilator-dependent patients.

Arterial Wave Reflection and Aortic Valve Calcification in an Elderly Community-Based Cohort

PubMed Central

Sera, Fusako; Russo, Cesare; Iwata, Shinichi; Jin, Zhezhen; Rundek, Tatjana; Elkind, Mitchell S.V.; Homma, Shunichi; Sacco, Ralph L.; Di Tullio, Marco R.

2015-01-01

Background Aortic valve calcification (AVC) without stenosis is common in the elderly, is associated with cardiovascular morbidity and mortality, and may progress to aortic valve stenosis. Arterial stiffness and pulse wave reflection are important components of proximal aortic hemodynamics, but their relationship with AVC is not established. Methods To investigate the relationship of arterial wave reflection and stiffness with AVC, pulse wave analysis and AVC evaluation by echocardiography were performed in 867 participants from the Cardiovascular Abnormalities and Brain Lesions (CABL) study. Participants were divided into 4 categories based on the severity and extent of AVC: 1) none or mild focal AVC; 2) mild diffuse AVC; 3) moderate-severe focal AVC; and 4) moderate-severe diffuse AVC. Central blood pressures and pulse pressure, total arterial compliance, augmentation index, and time to wave reflection were assessed using applanation tonometry. Results Indicators of arterial stiffness and wave reflection were significantly associated with AVC severity, except for central systolic and diastolic pressures and time to reflection. After adjustment for pertinent covariates (age, sex, race/ethnicity, and eGFR), only augmentation pressure (P = .02) and augmentation index (P = .002) were associated with the severity of AVC. Multivariable logistic regression analysis revealed that augmentation pressure (odds ratio per mmHg = 1.14; 95% confidence interval, 1.02–1.27; P = .02) and augmentation index (odds ratio per percentage point = 1.07; 95% confidence interval, 1.01–1.13; P = .02) were associated with an increase risk of moderate-severe diffuse AVC, even when central blood pressure value was included in the same model. Conclusions Arterial wave reflection is associated with AVC severity, independent of blood pressure values. Increased contribution of wave reflection to central blood pressure could be involved in the process leading to AVC. PMID:25600036

Arterial wave reflection and subclinical atherosclerosis in rheumatoid arthritis.

PubMed

Gunter, Sule; Robinson, Chanel; Woodiwiss, Angela J; Norton, Gavin R; Hsu, Hon-Chun; Solomon, Ahmed; Tsang, Linda; Millen, Aletta M E; Dessein, Patrick H

2018-01-01

Atherosclerotic cardiovascular disease risk is increased in rheumatoid arthritis (RA). Wave reflection occurs at arterial branching points, which are particularly prone to atherosclerosis. We explored the relationship of wave reflection with atherosclerosis in RA. One hundred and sixty three RA patients (110 white, 31 Asian, 17 black and 5 of mixed ancestry) without cardiovascular disease participated. Arterial stiffness, wave reflection, pressure pulsatility, plaque in the extracranial carotid artery tree and the mean of the left and right common carotid arteries intima-thickness were determined. Associations were identified in multivariable regression models. One SD increase in reflected wave pressure (OR (95% CI) = 2.54 (1.41-4.44), p=0.001), reflection magnitude (OR (95% CI) = 1.84 (1.17-2.89), p=0.008), central pulse pressure (OR (95% CI) = 1.89 (1.12-3.22), p=0.02) and peripheral pulse pressure (OR (95% CI) = 2.09 (1.23-3.57), p=0.007) were associated with plaque. The association of wave reflection with plaque was independent of arterial stiffness and pressure pulsatility, and was present in both hypertensive and normotensive RA patients. In receiver operator characteristic curve analysis, the optimal cutoff value for reflected wave pressure in predicting plaque presence was 25 mmHg with a sensitivity, specificity, positive predictive value and negative predictive value of 45.2%, 89.3%, 78.6% and 66.2%, respectively; a reflected wave pressure of >25 mmHg was associated with plaque in univariate and adjusted analysis (p<0.0001 for both). Arterial function was not independently related to carotid intima-media thickness. Consideration and therapeutic targeting of wave reflection may improve cardiovascular disease prevention in RA.

Numerical modeling and characterization of blast waves for application in blast-induced mild traumatic brain injury research

NASA Astrophysics Data System (ADS)

Phillips, Michael G.

Human exposure to blast waves, including blast-induced traumatic brain injury, is a developing field in medical research. Experiments with explosives have many disadvantages including safety, cost, and required area for trials. Shock tubes provide an alternative method to produce free field blast wave profiles. A compressed nitrogen shock tube experiment instrumented with static and reflective pressure taps is modeled using a numerical simulation. The geometry of the numerical model is simplified and blast wave characteristics are derived based upon static and pressure profiles. The pressure profiles are analyzed along the shock tube centerline and radially away from the tube axis. The blast wave parameters found from the pressure profiles provide guidelines for spatial location of a specimen. The location could be based on multiple parameters and provides a distribution of anticipated pressure profiles experience by the specimen.

Fundamental Studies of Transient, Atmospheric-Pressure, Small-Scale Plasmas

DTIC Science & Technology

2017-01-23

e.g. plasma brush) were explored for surface decontamination against pathogenic bacteria and biofilms , as well as for treatment of cervical cancer , in...pressure plasma jets and jet arrays (e.g. plasma brush) were explored for surface decontamination against pathogenic bacteria and biofilms , as well as...for treatment of cervical cancer , in vitro. 4) Other studies involving portable nanosecond pulsed power generation based gas switches or

Near-infrared reflectance of zunyite: implications for field mapping and remote-sensing detection of hydrothermally altered high alumina rocks.

USGS Publications Warehouse

Crowley, J.K.

1984-01-01

Several hydroxyl-bearing minerals have diagnostic absorption bands in the 2.0-2.4 mu m wave length range, and can be identified with an orbital radiometer and with high-resolution airborne and field portable spectrometers. Among such minerals, zunyite, 143Al13Si5O20(OH,F)18Cl, has distinctive spectral absorption characteristics and is notably restricted to, and thus an indicator mineral of, advanced argillic alteration. Although seldom noted because it visually resembles quartz, zunyite is probably not as rare as generally believed. Laboratory measurements and general considerations underlie suggestions favouring the feasibility of detecting zunyite, alone and in mixtures with other Al-OH minerals, using field portable spectrometers.-G.J.N.

Design and Implementation of an Electronic Front-End Based on Square Wave Excitation for Ultrasonic Torsional Guided Wave Viscosity Sensor

PubMed Central

Rabani, Amir

2016-01-01

The market for process instruments generally requires low cost devices that are robust, small in size, portable, and usable in-plant. Ultrasonic torsional guided wave sensors have received much attention by researchers for measurement of viscosity and/or density of fluids in recent years. The supporting electronic systems for these sensors providing many different settings of sine-wave signals are bulky and expensive. In contrast, a system based on bursts of square waves instead of sine waves would have a considerable advantage in that respect and could be built using simple integrated circuits at a cost that is orders of magnitude lower than for a windowed sine wave device. This paper explores the possibility of using square wave bursts as the driving signal source for the ultrasonic torsional guided wave viscosity sensor. A simple design of a compact and fully automatic analogue square wave front-end for the sensor is also proposed. The successful operation of the system is demonstrated by using the sensor for measuring the viscosity in a representative fluid. This work provides the basis for design and manufacture of low cost compact standalone ultrasonic guided wave sensors and enlightens the possibility of using coded excitation techniques utilising square wave sequences in such applications. PMID:27754324

Design and Implementation of an Electronic Front-End Based on Square Wave Excitation for Ultrasonic Torsional Guided Wave Viscosity Sensor.

PubMed

Rabani, Amir

2016-10-12

The market for process instruments generally requires low cost devices that are robust, small in size, portable, and usable in-plant. Ultrasonic torsional guided wave sensors have received much attention by researchers for measurement of viscosity and/or density of fluids in recent years. The supporting electronic systems for these sensors providing many different settings of sine-wave signals are bulky and expensive. In contrast, a system based on bursts of square waves instead of sine waves would have a considerable advantage in that respect and could be built using simple integrated circuits at a cost that is orders of magnitude lower than for a windowed sine wave device. This paper explores the possibility of using square wave bursts as the driving signal source for the ultrasonic torsional guided wave viscosity sensor. A simple design of a compact and fully automatic analogue square wave front-end for the sensor is also proposed. The successful operation of the system is demonstrated by using the sensor for measuring the viscosity in a representative fluid. This work provides the basis for design and manufacture of low cost compact standalone ultrasonic guided wave sensors and enlightens the possibility of using coded excitation techniques utilising square wave sequences in such applications.

Development of a piezopolymer pressure sensor for a portable fetal heart rate monitor

NASA Technical Reports Server (NTRS)

Zuckerwar, A. J.; Pretlow, R. A.; Stoughton, J. W.; Baker, D. A.

1993-01-01

A piezopolymer pressure sensor has been developed for service in a portable fetal heart rate monitor, which will permit an expectant mother to perform the fetal nonstress test, a standard predelivery test, in her home. Several sensors are mounted in an array on a belt worn by the mother. The sensor design conforms to the distinctive features of the fetal heart tone, namely, the acoustic signature, frequency spectrum, signal amplitude, and localization. The components of a sensor serve to fulfill five functions: signal detection, acceleration cancellation, acoustical isolation, electrical shielding, and electrical isolation of the mother. A theoretical analysis of the sensor response yields a numerical value for the sensor sensitivity, which is compared to experiment in an in vitro sensor calibration. Finally, an in vivo test on patients within the last six weeks of term reveals that nonstress test recordings from the acoustic monitor compare well with those obtained from conventional ultrasound.

Wave height estimates from pressure and velocity data at an intermediate depth in the presence of uniform currents

NASA Astrophysics Data System (ADS)

Basu, Biswajit

2017-12-01

Bounds on estimates of wave heights (valid for large amplitudes) from pressure and flow measurements at an arbitrary intermediate depth have been provided. Two-dimensional irrotational steady water waves over a flat bed with a finite depth in the presence of underlying uniform currents have been considered in the analysis. Five different upper bounds based on a combination of pressure and velocity field measurements have been derived, though there is only one available lower bound on the wave height in the case of the speed of current greater than or less than the wave speed. This article is part of the theme issue 'Nonlinear water waves'.

Pressure-gradient-driven nearshore circulation on a beach influenced by a large inlet-tidal shoal system

USGS Publications Warehouse

Shi, F.; Hanes, D.M.; Kirby, J.T.; Erikson, L.; Barnard, P.; Eshleman, J.

2011-01-01

The nearshore circulation induced by a focused pattern of surface gravity waves is studied at a beach adjacent to a major inlet with a large ebb tidal shoal. Using a coupled wave and wave-averaged nearshore circulation model, it is found that the nearshore circulation is significantly affected by the heterogeneous wave patterns caused by wave refraction over the ebb tidal shoal. The model is used to predict waves and currents during field experiments conducted near the mouth of San Francisco Bay and nearby Ocean Beach. The field measurements indicate strong spatial variations in current magnitude and direction and in wave height and direction along Ocean Beach and across the ebb tidal shoal. Numerical simulations suggest that wave refraction over the ebb tidal shoal causes wave focusing toward a narrow region at Ocean Beach. Due to the resulting spatial variation in nearshore wave height, wave-induced setup exhibits a strong alongshore nonuniformity, resulting in a dramatic change in the pressure field compared to a simulation with only tidal forcing. The analysis of momentum balances inside the surf zone shows that, under wave conditions with intensive wave focusing, the alongshore pressure gradient associated with alongshore nonuniform wave setup can be a dominant force driving circulation, inducing heterogeneous alongshore currents. Pressure-gradient- forced alongshore currents can exhibit flow reversals and flow convergence or divergence, in contrast to the uniform alongshore currents typically caused by tides or homogeneous waves.

The Physical Effects of Detonation in a Closed Cylindrical Chamber

NASA Technical Reports Server (NTRS)

Draper, C S

1935-01-01

Detonation in the internal-combustion engine is studied as a physical process. It is shown that detonation is accompanied by pressure waves within the cylinder charge. Sound theory is applied to the calculation of resonant pressure-wave frequencies. Apparatus is described for direct measurement of pressure-wave frequencies. Frequencies determined from two engines of different cylinder sizes are shown to agree with the values calculated from sound theory. An outline of the theoretically possible modes of vibration in a right circular cylinder with flat ends is included. An appendix by John P. Elting gives a method of calculating pressure in the sound wave following detonation.

Design of a Continuous Blood Pressure Measurement System Based on Pulse Wave and ECG Signals.

PubMed

Li, Jian-Qiang; Li, Rui; Chen, Zhuang-Zhuang; Deng, Gen-Qiang; Wang, Huihui; Mavromoustakis, Constandinos X; Song, Houbing; Ming, Zhong

2018-01-01

With increasingly fierce competition for jobs, the pressures on people have risen in recent years, leading to lifestyle and diet disorders that result in significantly higher risks of cardiovascular disease. Hypertension is one of the common chronic cardiovascular diseases; however, mainstream blood pressure measurement devices are relatively heavy. When multiple measurements are required, the user experience and the measurement results may be unsatisfactory. In this paper, we describe the design of a signal collection module that collects pulse waves and electrocardiograph (ECG) signals. The collected signals are input into a signal processing module to filter the noise and amplify the useful physiological signals. Then, we use a wavelet transform to eliminate baseline drift noise and detect the feature points of the pulse waves and ECG signals. We propose the concept of detecting the wave shape associated with an instance, an approach that minimizes the impact of atypical pulse waves on blood pressure measurements. Finally, we propose an improved method for measuring blood pressure based on pulse wave velocity that improves the accuracy of blood pressure measurements by 58%. Moreover, the results meet the american medical instrument promotion association standards, which demonstrate the feasibility of our measurement system.

Design of a Continuous Blood Pressure Measurement System Based on Pulse Wave and ECG Signals

PubMed Central

Li, Jian-Qiang; Li, Rui; Chen, Zhuang-Zhuang; Deng, Gen-Qiang; Wang, Huihui; Mavromoustakis, Constandinos X.; Ming, Zhong

2018-01-01

With increasingly fierce competition for jobs, the pressures on people have risen in recent years, leading to lifestyle and diet disorders that result in significantly higher risks of cardiovascular disease. Hypertension is one of the common chronic cardiovascular diseases; however, mainstream blood pressure measurement devices are relatively heavy. When multiple measurements are required, the user experience and the measurement results may be unsatisfactory. In this paper, we describe the design of a signal collection module that collects pulse waves and electrocardiograph (ECG) signals. The collected signals are input into a signal processing module to filter the noise and amplify the useful physiological signals. Then, we use a wavelet transform to eliminate baseline drift noise and detect the feature points of the pulse waves and ECG signals. We propose the concept of detecting the wave shape associated with an instance, an approach that minimizes the impact of atypical pulse waves on blood pressure measurements. Finally, we propose an improved method for measuring blood pressure based on pulse wave velocity that improves the accuracy of blood pressure measurements by 58%. Moreover, the results meet the american medical instrument promotion association standards, which demonstrate the feasibility of our measurement system. PMID:29541556

One-dimensional pressure transfer models for acoustic-electric transmission channels

NASA Astrophysics Data System (ADS)

Wilt, K. R.; Lawry, T. J.; Scarton, H. A.; Saulnier, G. J.

2015-09-01

A method for modeling piezoelectric-based ultrasonic acoustic-electric power and data transmission channels is presented. These channels employ piezoelectric disk transducers to convey signals across a series of physical layers using ultrasonic waves. This model decomposes the mechanical pathway of the signal into individual ultrasonic propagation layers which are generally independent of the layer's adjacent domains. Each layer is represented by a two-by-two traveling pressure wave transfer matrix which relates the forward and reverse pressure waves on one side of the layer to the pressure waves on the opposite face, where each face is assumed to be in contact with a domain of arbitrary reference acoustic impedance. A rigorous implementation of ultrasonic beam spreading is introduced and implemented within applicable domains. Compatible pressure-wave models for piezoelectric transducers are given, which relate the electric voltage and current interface of the transducer to the pressure waves on one mechanical interface while also allowing for passive acoustic loading of the secondary mechanical interface. It is also shown that the piezoelectric model's electrical interface is compatible with transmission line parameters (ABCD-parameters), allowing for connection of electronic components and networks. The model is shown to be capable of reproducing the behavior of realistic physical channels.

Relationships between 24-h blood pressure variability and 24-h central arterial pressure, pulse wave velocity and augmentation index in hypertensive patients.

PubMed

Omboni, Stefano; Posokhov, Igor N; Rogoza, Anatoly N

2017-04-01

Twenty-four-h blood pressure variability (BPV) predicts cardiovascular complications in hypertension, but its association with pulse wave indices (central arterial pressure, pulse wave velocity (PWV) and augmentation index (AIx)) is poorly understood. In the present study, we assessed the degree of the effect of 24-h BPV on 24-h pulse wave indices. Brachial blood pressure was measured non-invasively over the 24 h with an electronic, oscillometric, automated device (BPLab) in 661 uncomplicated treated or untreated hypertensive patients. Digitalized oscillometric waveforms were analyzed with a validated algorithm to obtain pulse wave indices. Twenty-four-h BPV was calculated as the unweighted (SDu) or weighted s.d. (SDw) of the mean blood pressure or as the average real variability (ARV). Twenty-four-h systolic BPV showed a direct and significant relationship with the central arterial systolic pressure (r=0.28 SDu, r=0.40 SDw, r=0.34 ARV), PWV (r=0.10 SDu, r=0.21 SDw, r=0.19 ARV) and AIx (r=0.17 SDu, r=0.27 SDw, r=0.23 ARV). After adjustment for age, sex, body mass index, antihypertensive treatment and 24-h systolic blood pressure, the relationship lost some power but was still significant for all measures, except for the AIx. Pulse wave indices were higher in patients with high BPV than in those with low BPV: after adjustment, these differences were abolished for the AIx. The diastolic BPV showed a weak association with the pulse wave indices. In conclusion, in hypertensive patients, 24-h systolic BPV is moderately and independently associated with 24-h central arterial pressure and stiffness.

Multiheterodyne spectroscopy using interband cascade lasers

NASA Astrophysics Data System (ADS)

Sterczewski, Lukasz A.; Westberg, Jonas; Patrick, Charles Link; Kim, Chul Soo; Kim, Mijin; Canedy, Chadwick L.; Bewley, William W.; Merritt, Charles D.; Vurgaftman, Igor; Meyer, Jerry R.; Wysocki, Gerard

2018-01-01

While midinfrared radiation can be used to identify and quantify numerous chemical species, contemporary broadband midinfrared spectroscopic systems are often hindered by large footprints, moving parts, and high power consumption. In this work, we demonstrate multiheterodyne spectroscopy (MHS) using interband cascade lasers, which combines broadband spectral coverage with high spectral resolution and energy-efficient operation. The lasers generate up to 30 mW of continuous-wave optical power while consuming <0.5 W of electrical power. A computational phase and timing correction algorithm is used to obtain kHz linewidths of the multiheterodyne beat notes and up to 30 dB improvement in signal-to-noise ratio. The versatility of the multiheterodyne technique is demonstrated by performing both rapidly swept absorption and dispersion spectroscopic assessments of low-pressure ethylene (C2H4) acquired by extracting a single beat note from the multiheterodyne signal, as well as broadband MHS of methane (CH4) acquired with all available beat notes with microsecond temporal resolution and an instantaneous optical bandwidth of ˜240 GHz. The technology shows excellent potential for portable and high-resolution solid-state spectroscopic chemical sensors operating in the midinfrared.

Focusing of shock waves induced by optical breakdown in water

PubMed Central

Sankin, Georgy N.; Zhou, Yufeng; Zhong, Pei

2008-01-01

The focusing of laser-generated shock waves by a truncated ellipsoidal reflector was experimentally and numerically investigated. Pressure waveform and distribution around the first (F1) and second foci (F2) of the ellipsoidal reflector were measured. A neodymium doped yttrium aluminum garnet laser of 1046 nm wavelength and 5 ns pulse duration was used to create an optical breakdown at F1, which generates a spherically diverging shock wave with a peak pressure of 2.1–5.9 MPa at 1.1 mm stand-off distance and a pulse width at half maximum of 36–65 ns. Upon reflection, a converging shock wave is produced which, upon arriving at F2, has a leading compressive wave with a peak pressure of 26 MPa and a zero-crossing pulse duration of 0.1 μs, followed by a trailing tensile wave of −3.3 MPa peak pressure and 0.2 μs pulse duration. The −6 dB beam size of the focused shock wave field is 1.6×0.2 mm2 along and transverse to the shock wave propagation direction. Formation of elongated plasmas at high laser energy levels limits the increase in the peak pressure at F2. General features in the waveform profile of the converging shock wave are in qualitative agreement with numerical simulations based on the Hamilton model. PMID:18537359

Kinematics and dynamics of green water on a fixed platform in a large wave basin in focusing wave and random wave conditions

NASA Astrophysics Data System (ADS)

Chuang, Wei-Liang; Chang, Kuang-An; Mercier, Richard

2018-06-01

Green water kinematics and dynamics due to wave impingements on a simplified geometry, fixed platform were experimentally investigated in a large, deep-water wave basin. Both plane focusing waves and random waves were employed in the generation of green water. The focusing wave condition was designed to create two consecutive plunging breaking waves with one impinging on the frontal vertical wall of the fixed platform, referred as wall impingement, and the other directly impinging on the deck surface, referred as deck impingement. The random wave condition was generated using the JONSWAP spectrum with a significant wave height approximately equal to the freeboard. A total of 179 green water events were collected in the random wave condition. By examining the green water events in random waves, three different flow types are categorized: collapse of overtopping wave, fall of bulk water, and breaking wave crest. The aerated flow velocity was measured using bubble image velocimetry, while the void fraction was measured using fiber optic reflectometry. For the plane focusing wave condition, measurements of impact pressure were synchronized with the flow velocity and void fraction measurements. The relationship between the peak pressures and the pressure rise times is examined. For the high-intensity impact in the deck impingement events, the peak pressures are observed to be proportional to the aeration levels. The maximum horizontal velocities in the green water events in random waves are well represented by the lognormal distribution. Ritter's solution is shown to quantitatively describe the green water velocity distributions under both the focusing wave condition and the random wave condition. A prediction equation for green water velocity distribution under random waves is proposed.

Pressures, flow, and brain oxygenation during plateau waves of intracranial pressure.

PubMed

Dias, Celeste; Maia, Isabel; Cerejo, António; Varsos, Georgios; Smielewski, Peter; Paiva, José-Artur; Czosnyka, Marek

2014-08-01

Plateau waves are common in traumatic brain injury. They constitute abrupt increases of intracranial pressure (ICP) above 40 mmHg associated with a decrease in cerebral perfusion pressure (CPP). The aim of this study was to describe plateau waves characteristics with multimodal brain monitoring in head injured patients admitted in neurocritical care. Prospective observational study in 18 multiple trauma patients with head injury admitted to Neurocritical Care Unit of Hospital Sao Joao in Porto. Multimodal systemic and brain monitoring of primary variables [heart rate, arterial blood pressure, ICP, CPP, pulse amplitude, end tidal CO₂, brain temperature, brain tissue oxygenation pressure, cerebral oximetry (CO) with transcutaneous near-infrared spectroscopy and cerebral blood flow (CBF)] and secondary variables related to cerebral compensatory reserve and cerebrovascular reactivity were supported by dedicated software ICM+ ( www.neurosurg.cam.ac.uk/icmplus) . The compiled data were analyzed in patients who developed plateau waves. In this study we identified 59 plateau waves that occurred in 44% of the patients (8/18). During plateau waves CBF, cerebrovascular resistance, CO, and brain tissue oxygenation decreased. The duration and magnitude of plateau waves were greater in patients with working cerebrovascular reactivity. After the end of plateau wave, a hyperemic response was recorded in 64% of cases with increase in CBF and brain oxygenation. The magnitude of hyperemia was associated with better autoregulation status and low oxygenation levels at baseline. Multimodal brain monitoring facilitates identification and understanding of intrinsic vascular brain phenomenon, such as plateau waves, and may help the adequate management of acute head injury at bed side.

Pressure-wave energy relationship during IABP counterpulsation in a mock circulation: changes with angle and assisting frequency.

PubMed

Biglino, Giovanni; Kolyva, Christina; Khir, Ashraf W

2012-01-01

Despite decades of successful clinical use of the intra aortic balloon pump (IABP), certain aspects of its operation are not yet fully understood. This work aims to investigate in vitro the mechanism underlying balloon inflation and deflation with varying assisting frequency and operating angle with respect to the horizontal, by studying the corresponding pressure and wave energy changes. A mock circulatory system (MCS), with physiological distribution of peripheral resistance and compliance, presented a controllable test bed. We used Wave Intensity Analysis (WIA) to identify balloon-generated waves and quantify their energy. Conventional hemodynamic parameters were also calculated. Tests were repeated at varying operating angles (0°-45°), resembling the semi-recumbent position in the ICU, and at different assisting frequencies (1:1, 1:2, 1:3). Two balloons (25 cc and 40 cc in volume) were tested. The main waves associated with counterpulsation were identified as a backward compression wave associated with balloon inflation and a backward expansion wave associated with balloon deflation. Results showed that the IABP inflation and deflation benefits are reduced with increasing angle, in terms of the size of the inflation and deflation waves as well as in terms of diastolic pressure augmentation and end-diastolic pressure reduction. Both WIA findings and pressure parameters indicated 1:1 as the most effective mode of pumping. This study shows that, in vitro, a greater benefit of counterpulsation can be achieved in the horizontal position at 1:1 assisting frequency, with a good correlation between wave and pressure results.

Probability Analysis of the Wave-Slamming Pressure Values of the Horizontal Deck with Elastic Support

NASA Astrophysics Data System (ADS)

Zuo, Weiguang; Liu, Ming; Fan, Tianhui; Wang, Pengtao

2018-06-01

This paper presents the probability distribution of the slamming pressure from an experimental study of regular wave slamming on an elastically supported horizontal deck. The time series of the slamming pressure during the wave impact were first obtained through statistical analyses on experimental data. The exceeding probability distribution of the maximum slamming pressure peak and distribution parameters were analyzed, and the results show that the exceeding probability distribution of the maximum slamming pressure peak accords with the three-parameter Weibull distribution. Furthermore, the range and relationships of the distribution parameters were studied. The sum of the location parameter D and the scale parameter L was approximately equal to 1.0, and the exceeding probability was more than 36.79% when the random peak was equal to the sample average during the wave impact. The variation of the distribution parameters and slamming pressure under different model conditions were comprehensively presented, and the parameter values of the Weibull distribution of wave-slamming pressure peaks were different due to different test models. The parameter values were found to decrease due to the increased stiffness of the elastic support. The damage criterion of the structure model caused by the wave impact was initially discussed, and the structure model was destroyed when the average slamming time was greater than a certain value during the duration of the wave impact. The conclusions of the experimental study were then described.

Refrigeration system having standing wave compressor

DOEpatents

Lucas, Timothy S.

1992-01-01

A compression-evaporation refrigeration system, wherein gaseous compression of the refrigerant is provided by a standing wave compressor. The standing wave compressor is modified so as to provide a separate subcooling system for the refrigerant, so that efficiency losses due to flashing are reduced. Subcooling occurs when heat exchange is provided between the refrigerant and a heat pumping surface, which is exposed to the standing acoustic wave within the standing wave compressor. A variable capacity and variable discharge pressure for the standing wave compressor is provided. A control circuit simultaneously varies the capacity and discharge pressure in response to changing operating conditions, thereby maintaining the minimum discharge pressure needed for condensation to occur at any time. Thus, the power consumption of the standing wave compressor is reduced and system efficiency is improved.

On the Exit Boundary Condition for One-Dimensional Calculations of Pulsed Detonation Engine Performance

NASA Technical Reports Server (NTRS)

Wilson, Jack; Paxson, Daniel E.

2002-01-01

In one-dimensional calculations of pulsed detonation engine (PDE) performance, the exit boundary condition is frequently taken to be a constant static pressure. In reality, for an isolated detonation tube, after the detonation wave arrives at the exit plane, there will be a region of high pressure, which will gradually return to ambient pressure as an almost spherical shock wave expands away from the exit, and weakens. Initially, the flow is supersonic, unaffected by external pressure, but later becomes subsonic. Previous authors have accounted for this situation either by assuming the subsonic pressure decay to be a relaxation phenomenon, or by running a two-dimensional calculation first, including a domain external to the detonation tube, and using the resulting exit pressure temporal distribution as the boundary condition for one-dimensional calculations. These calculations show that the increased pressure does affect the PDE performance. In the present work, a simple model of the exit process is used to estimate the pressure decay time. The planar shock wave emerging from the tube is assumed to transform into a spherical shock wave. The initial strength of the spherical shock wave is determined from comparison with experimental results. Its subsequent propagation, and resulting pressure at the tube exit, is given by a numerical blast wave calculation. The model agrees reasonably well with other, limited, results. Finally, the model was used as the exit boundary condition for a one-dimensional calculation of PDE performance to obtain the thrust wall pressure for a hydrogen-air detonation in tubes of length to diameter ratio (L/D) of 4, and 10, as well as for the original, constant pressure boundary condition. The modified boundary condition had no performance impact for values of L/D > 10, and moderate impact for L/D = 4.

Solitary waves: a possible mechanism for rapid fluid transport in low permeability porous media

NASA Astrophysics Data System (ADS)

Appold, Martin; Joshi, Ajit

2014-05-01

Elastic porous media in which the rate of fluid pressure generation is high relative to the rate of fluid pressure diffusion and whose permeabilities are a sensitive function of effective stress may generate solitary waves manifest as discrete pulses of elevated pore pressure and porosity that can travel at velocities that are orders of magnitude greater than the velocities of the pore fluids in the background Darcian flow regime. Solitary waves may thus be important vehicles for fluid transport through porous media whose permeabilities are otherwise too low to allow significant rates of flow. Solitary waves have been hypothesized for diverse geologic settings and processes, including magmatic hydrothermal ore formation, magma transport, fault slip in accretionary wedges and at transform plate boundaries, and primary hydrocarbon migration in sedimentary basins. The present study has focused on solitary waves as agents of oil and methane transport through numerical simulation of their origin and behavior. The results show solitary waves to have limited capacity for transporting oil for several reasons: (1) the rate of fluid pressure generation by typical mechanisms like compaction disequilibrium and hydrocarbon formation is too low to allow solitary waves to form unless permeability is exceptionally low (10-24 to 10-25 m2), (2) solitary waves are only able to ascend no more than 1-2 km before dissipating to ambient pressure and porosity values, (3) the waves are too small and the frequency of their formation is too low to account for the amount of oil observed in the reservoirs that they have been hypothesized to feed. Solitary waves have been found to be more effective at transporting methane because of its lower density and viscosity compared to oil, provided that a mechanism for rapid pressure generation exists and permeabilities are very low. If those conditions exist, then solitary waves can ascend over two kilometers at rates on the order of 100's of meters per year compared to millimeters per year for solitary waves transporting oil.

Laboratory modeling of edge wave generation over a plane beach by breaking waves

NASA Astrophysics Data System (ADS)

Abcha, Nizar; Ezersky, Alexander; Pelinovsky, Efim

2015-04-01

Edge waves play an important role in coastal hydrodynamics: in sediment transport, in formation of coastline structure and coastal bottom topography. Investigation of physical mechanisms leading to the edge waves generation allows us to determine their effect on the characteristics of spatially periodic patterns like crescent submarine bars and cusps observed in the coastal zone. In the present paper we investigate parametric excitation of edge wave with frequency two times less than the frequency of surface wave propagating perpendicular to the beach. Such mechanism of edge wave generation has been studied previously in a large number of papers using the assumption of non-breaking waves. This assumption was used in theoretical calculations and such conditions were created in laboratory experiments. In the natural conditions, the wave breaking is typical when edge waves are generated at sea beach. We study features of such processes in laboratory experiments. Experiments were performed in the wave flume of the Laboratory of Continental and Coast Morphodynamics (M2C), Caen. The flume is equipment with a wave maker controlled by computer. To model a plane beach, a PVC plate is placed at small angle to the horizontal bottom. Several resistive probes were used to measure characteristics of waves: one of them was used to measure free surface displacement near the wave maker and two probes were glued on the inclined plate. These probes allowed us to measure run-up due to parametrically excited edge waves. Run-up height is determined by processing a movie shot by high-speed camera. Sub-harmonic generation of standing edge waves is observed for definite control parameters: edge waves represent themselves a spatial mode with wavelength equal to double width of the flume; the frequency of edge wave is equal to half of surface wave frequency. Appearance of sub-harmonic mode instability is studied using probes and movie processing. The dependence of edge wave exponential growth rate index on the amplitude of surface wave is found. On the plane of parameters (amplitude - frequency) of surface wave we have found a region corresponding parametric instability leading to excitation of edge waves. It is shown that for small super criticalities, the amplitude of edge wave grows with amplitude of surface wave. For large amplitude of surface wave, wave breaking appears and parametric instability is suppressed. Such suppression of instability is caused by increasing of turbulent viscosity in near shore zone. It was shown that parametric excitation of edge wave can increase significantly (up to two times) the maximal run-up. Theoretical model is developed to explain suppression of instability due to turbulent viscosity. This theoretical model is based on nonlinear mode amplitude equation including terms responsible for parametric forcing, frequency detuning, nonlinear detuning, linear and nonlinear edge wave damping. Dependence of coefficients on turbulent viscosity is discussed.

Power and Thermal Technologies for Air and Space-Scientific Research Program. Delivery Order 0017: Study of Microchip Power Module Materials Using Mini-Channel Heat Exchanger

DTIC Science & Technology

2009-12-01

pressure transducers were calibrated (designated INLET and EXIT) using a portable pressure calibrator ( Druck , DPI 610). The unit has an accuracy of 0.025...of full scale (fs) with macro and micro pressure adjustment capabilities. The Druck pressure range was 14.7-300 psia. The transducers (Omega PX303...050A5V) had a range of 0-50 psig with an output voltage of 0.5-5 VDC. The inlet and exit transducers were calibrated separately using the Druck

Portable FAIMS: Applications and Future Perspectives.

PubMed

Costanzo, Michael T; Boock, Jared J; Kemperman, Robin H J; Wei, Michael S; Beekman, Christopher R; Yost, Richard A

2017-11-01

Miniaturized mass spectrometry (MMS) is optimal for a wide variety of applications that benefit from field-portable instrumentation. Like MMS, field asymmetric ion mobility spectrometry (FAIMS) has proven capable of providing in situ analysis, allowing researchers to bring the lab to the sample. FAIMS compliments MMS very well, but has the added benefit of operating at atmospheric pressure, unlike MS. This distinct advantage makes FAIMS uniquely suited for portability. Since its inception, FAIMS has been envisioned as a field-portable device, as it affords less expense and greater simplicity than many similar methods. Ideally, these are simple, robust devices that may be operated by non-professional personnel, yet still provide adequate data when in the field. While reducing the size and complexity tends to bring with it a loss of performance and accuracy, this is made up for by the incredibly high throughput and overall convenience of the instrument. Moreover, the FAIMS device used in the field can be brought back to the lab, and coupled to a conventional mass spectrometer to provide any necessary method development and compound validation. This work discusses the various considerations, uses, and applications for portable FAIMS instrumentation, and how the future of each applicable field may benefit from the development and acceptance of such a device.

On the use of volumetric strain meters to infer additional characteristics of short-period seismic radiation

USGS Publications Warehouse

Borcherdt, R.D.; Johnston, M.J.S.; Glassmoyer, G.

1989-01-01

Volumetric strain meters (Sacks-Evertson design) are installed at 15 sites along the San Andreas fault system, to monitor long-term strain changes for earthquake prediction. Deployment of portable broadband, high-resolution digital recorders (GEOS) at several of the sites extends the detection band for volumetric strain to periods shorter than 5 ?? 10-2 sec and permits the simultaneous observation of seismic radiation fields using conventional short-period pendulum seismometers. Recordings of local and regional earthquakes indicate that dilatometers respond to P energy but not direct shear energy and that straingrams can be used to resolve superimposed reflect P and S waves for inference of wave characteristics not permitted by either sensor alone. Simultaneous measurements of incident P- and S-wave amplitudes are used to introduce a technique for single-station estimates of wave field inhomogeneity, free-surface reflection coefficients and local material P velocity. -from Authors

Simulating electron wave dynamics in graphene superlattices exploiting parallel processing advantages

NASA Astrophysics Data System (ADS)

Rodrigues, Manuel J.; Fernandes, David E.; Silveirinha, Mário G.; Falcão, Gabriel

2018-01-01

This work introduces a parallel computing framework to characterize the propagation of electron waves in graphene-based nanostructures. The electron wave dynamics is modeled using both "microscopic" and effective medium formalisms and the numerical solution of the two-dimensional massless Dirac equation is determined using a Finite-Difference Time-Domain scheme. The propagation of electron waves in graphene superlattices with localized scattering centers is studied, and the role of the symmetry of the microscopic potential in the electron velocity is discussed. The computational methodologies target the parallel capabilities of heterogeneous multi-core CPU and multi-GPU environments and are built with the OpenCL parallel programming framework which provides a portable, vendor agnostic and high throughput-performance solution. The proposed heterogeneous multi-GPU implementation achieves speedup ratios up to 75x when compared to multi-thread and multi-core CPU execution, reducing simulation times from several hours to a couple of minutes.

Left atrial strain: a new parameter for assessment of left ventricular filling pressure.

PubMed

Cameli, Matteo; Mandoli, Giulia Elena; Loiacono, Ferdinando; Dini, Frank Lloyd; Henein, Michael; Mondillo, Sergio

2016-01-01

In order to obtain accurate diagnosis, treatment and prognostication in many cardiac conditions, there is a need for assessment of left ventricular (LV) filling pressure. While systole depends on ejection function of LV, diastole and its disturbances influence filling function and pressures. The commonest condition that represents the latter is heart failure with preserved ejection fraction in which LV ejection is maintained, but diastole is disturbed and hence filling pressures are raised. Significant diastolic dysfunction results in raised LV end-diastolic pressure, mean left atrial (LA) pressure and pulmonary capillary wedge pressure, all referred to as LV filling pressures. Left and right heart catheterization has traditionally been used as the gold standard investigation for assessing these pressures. More recently, Doppler echocardiography has taken over such application because of its noninvasive nature and for being patient friendly. A number of indices are used to achieve accurate assessment of filling pressures including: LV pulsed-wave filling velocities (E/A ratio, E wave deceleration time), pulmonary venous flow (S wave and D wave), tissue Doppler imaging (E' wave and E/E' ratio) and LA volume index. LA longitudinal strain derived from speckle tracking echocardiography (STE) is also sensitive in estimating intracavitary pressures. It is angle-independent, thus overcomes Doppler limitations and provides highly reproducible measures of LA deformation. This review examines the application of various Doppler echocardiographic techniques in assessing LV filling pressures, in particular the emerging role of STE in assessing LA pressures in various conditions, e.g., HF, arterial hypertension and atrial fibrillation.

Crustal structure of Australia from ambient seismic noise tomography

NASA Astrophysics Data System (ADS)

Saygin, Erdinc; Kennett, B. L. N.

2012-01-01

Surface wave tomography for Australian crustal structure has been carried out using group velocity measurements in the period range 1-32 s extracted from stacked correlations of ambient noise between station pairs. Both Rayleigh wave and Love wave group velocity maps are constructed for each period using the vertical and transverse component of the Green's function estimates from the ambient noise. The full suite of portable broadband deployments and permanent stations on the continent have been used with over 250 stations in all and up to 7500 paths. The permanent stations provide a useful link between the various shorter-term portable deployments. At each period the group velocity maps are constructed with a fully nonlinear tomographic inversion exploiting a subspace technique and the Fast Marching Method for wavefront tracking. For Rayleigh waves the continental coverage is good enough to allow the construction of a 3D shear wavespeed model in a two stage approach. Local group dispersion information is collated for a distribution of points across the continent and inverted for a 1D SV wavespeed profile using a Neighbourhood Algorithm method. The resulting set of 1D models are then interpolated to produce the final 3D wavespeed model. The group velocity maps show the strong influence of thick sediments at shorter periods, and distinct fast zones associated with cratonic regions. Below the sediments the 3D shear wavespeed model displays significant heterogeneity with only moderate correlation with surface tectonic features. For example, there is no evident expression of the Tasman Line marking the eastern edge of Precambrian outcrop. The large number of available inter-station paths extracted from the ambient noise analysis provide detailed shear wavespeed information for crustal structure across the Australian continent for the first time, including regions where there was no prior sampling because of difficult logistics.

[P wave dispersion increased in childhood depending on blood pressure, weight, height, and cardiac structure and function].

PubMed

Chávez-González, Elibet; González-Rodríguez, Emilio; Llanes-Camacho, María Del Carmen; Garí-Llanes, Merlin; García-Nóbrega, Yosvany; García-Sáez, Julieta

2014-01-01

Increased P wave dispersion are identified as a predictor of atrial fibrillation. There are associations between hypertension, P wave dispersion, constitutional and echocardiographic variables. These relationships have been scarcely studied in pediatrics. The aim of this study was to determine the relationship between P wave dispersion, blood pressure, echocardiographic and constitutional variables, and determine the most influential variables on P wave dispersion increases in pediatrics. In the frame of the PROCDEC II project, children from 8 to 11 years old, without known heart conditions were studied. Arterial blood pressure was measured in all the children; a 12-lead surface electrocardiogram and an echocardiogram were done as well. Left ventricular mass index mean values for normotensive (25.91±5.96g/m(2.7)) and hypertensive (30.34±8.48g/m(2.7)) showed significant differences P=.000. When we add prehypertensive and hypertensive there are 50.38% with normal left ventricular mass index and P wave dispersion was increased versus 13.36% of normotensive. Multiple regression demonstrated that the mean blood pressure, duration of A wave of mitral inflow, weight and height have a value of r=0.88 as related to P wave dispersion. P wave dispersion is increased in pre- and hypertensive children compared to normotensive. There are pre- and hypertensive patients with normal left ventricular mass index and increased P wave dispersion. Mean arterial pressure, duration of the A wave of mitral inflow, weight and height are the variables with the highest influence on increased P wave dispersion. Copyright © 2013 Instituto Nacional de Cardiología Ignacio Chávez. Published by Masson Doyma México S.A. All rights reserved.

Novel wave intensity analysis of arterial pulse wave propagation accounting for peripheral reflections

PubMed Central

Alastruey, Jordi; Hunt, Anthony A E; Weinberg, Peter D

2014-01-01

We present a novel analysis of arterial pulse wave propagation that combines traditional wave intensity analysis with identification of Windkessel pressures to account for the effect on the pressure waveform of peripheral wave reflections. Using haemodynamic data measured in vivo in the rabbit or generated numerically in models of human compliant vessels, we show that traditional wave intensity analysis identifies the timing, direction and magnitude of the predominant waves that shape aortic pressure and flow waveforms in systole, but fails to identify the effect of peripheral reflections. These reflections persist for several cardiac cycles and make up most of the pressure waveform, especially in diastole and early systole. Ignoring peripheral reflections leads to an erroneous indication of a reflection-free period in early systole and additional error in the estimates of (i) pulse wave velocity at the ascending aorta given by the PU–loop method (9.5% error) and (ii) transit time to a dominant reflection site calculated from the wave intensity profile (27% error). These errors decreased to 1.3% and 10%, respectively, when accounting for peripheral reflections. Using our new analysis, we investigate the effect of vessel compliance and peripheral resistance on wave intensity, peripheral reflections and reflections originating in previous cardiac cycles. PMID:24132888

A new approximation for pore pressure accumulation in marine sediment due to water waves

NASA Astrophysics Data System (ADS)

Jeng, D.-S.; Seymour, B. R.; Li, J.

2007-01-01

The residual mechanism of wave-induced pore water pressure accumulation in marine sediments is re-examined. An analytical approximation is derived using a linear relation for pore pressure generation in cyclic loading, and mistakes in previous solutions (Int. J. Numer. Anal. Methods Geomech. 2001; 25:885-907; J. Offshore Mech. Arctic Eng. (ASME) 1989; 111(1):1-11) are corrected. A numerical scheme is then employed to solve the case with a non-linear relation for pore pressure generation. Both analytical and numerical solutions are verified with experimental data (Laboratory and field investigation of wave-sediment interaction. Joseph H. Defrees Hydraulics Laboratory, School of Civil and Environmental Engineering, Cornell University, Ithaca, NY, 1983), and provide a better prediction of pore pressure accumulation than the previous solution (J. Offshore Mech. Arctic Eng. (ASME) 1989; 111(1):1-11). The parametric study concludes that the pore pressure accumulation and use of full non-linear relation of pore pressure become more important under the following conditions: (1) large wave amplitude, (2) longer wave period, (3) shallow water, (4) shallow soil and (5) softer soils with a low consolidation coefficient. Copyright

Comments on the possibility of cavitation in liquid metal targets for pulsed spallation neutron sources

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carpenter J.M.

When short pulses of protons strike the volume of a liquid target, the rapid heating produces a pressurized region which relaxes as the pressure wave propagates outward. Skala and Bauer have modeled the effects of the pressure wave impinging on the container walls of a liquid mercury target under ESS conditions. They find that high pressures and high wall stresses result if the medium is uniform, nearly incompressible liquid. The pressure and the stresses are much reduced if the liquid contains bubbles of helium, due to their high compressibility. However, according to the calculation, the pressure still reaches an atmospheremore » or so at the surface, which reflects the compressive wave as a rarefaction wave of the same magnitude. Even such modest underpressures can lead to the growth of bubbles (cavitation) at or near the surface, which can collapse violently and erode the container surface. It is necessary to avoid this. Leighton provides a wide ranging discussion of pressure waves in bubbly media, which may provide insights into the nature and control of cavitation phenomena. The paper surveys some of the relevant information from that source.« less

The Need for Non-Lethal Weapons in Major Combat Operations

DTIC Science & Technology

2008-04-23

and sent out a shock wave similar to a sonic boom that in theory could have downed a B-17 bomber. Its effects 4 were disabling, rather than...malodorants and toxic incapacitating agents) Mechanical technologies (including nets and barriers) Acoustic technologies (such as infra - and...oxide AUDIBLE INFRASONIC ULTRASONIC BARRIERS Caltrops Tire spikes and strips ENTANGLEMENTS Portable vehicle arresting barrier Running

Fighting The Network: Manet Management In Support Of Littoral Operations

DTIC Science & Technology

2016-03-01

Solomon , 2015). DL widens the scope of naval Surface Action Groups (SAG) operations, introducing the concept of Adaptive Force Package (AFP...be implemented in littoral tactical networks. CENETIX research utilizes three Wave Relay radio models for experimentation : the Man-Portable Unit...enable seamless continuity in the transfer of research knowledge to subsequent testing and CONOPS development. CENETIX field experimentation

Air Revitalization Using Superoxides

NASA Technical Reports Server (NTRS)

Wydeven, Theodore; Wood, Peter C.; Spitze, L. A.

1988-01-01

Pellets made from powder mixtures of potassium superoxide, KO2, and calcium superoxide, Ca(O2)2, proven markedly superior to pellets of pure KO2 for adding O2 to and removing CO2 from atmospheric-pressure flow of humidified CO2 in He. Superoxides used extensively to supply O2 and scrub CO2 in variety of ambient-pressure life-support applications, including portable self-contained breathing apparatuses, spacecraft, and undersea submersible craft.

White coat hypertension is more risky than prehypertension: important role of arterial wave reflections.

PubMed

Sung, Shih-Hsien; Cheng, Hao-Min; Wang, Kang-Ling; Yu, Wen-Chung; Chuang, Shao-Yuan; Ting, Chih-Tai; Lakatta, Edward G; Yin, Frank C P; Chou, Pesus; Chen, Chen-Huan

2013-06-01

Arterial aging may link cardiovascular risk to white coat hypertension (WCH). The aims of the present study were to investigate the role of arterial aging in the white coat effect, defined as the difference between office and 24-hour ambulatory systolic blood pressures, and to compare WCH with prehypertension (PH) with respect to target organ damage and long-term cardiovascular mortality. A total of 1257 never-been-treated volunteer subjects from a community-based survey were studied. WCH and PH were defined by office and 24-hour ambulatory blood pressures. Left ventricular mass index, carotid intima-media thickness, estimated glomerular filtration rate, carotid-femoral pulse wave velocity, carotid augmentation index, amplitude of the reflection pressure wave, and 15-year cardiovascular mortality were determined. Subjects with WCH were significantly older and had greater body mass index, blood pressure values, intima-media thickness, carotid-femoral pulse wave velocity, augmentation index, amplitude of the backward pressure wave, and a lower estimated glomerular filtration rate than PH. Amplitude of the backward pressure wave was the most important independent correlate of the white coat effect in multivariate analysis (model r(2)=0.451; partial r(2)/model r(2)=90.5%). WCH had significantly greater cardiovascular mortality than PH (hazard ratio, 2.94; 95% confidence interval, 1.09-7.91), after accounting for age, sex, body mass index, smoking, fasting plasma glucose, and total cholesterol/high-density lipoprotein-cholesterol ratio. Further adjustment of the model for amplitude of the backward pressure wave eliminated the statistical significance of the WCH effect. In conclusion, the white coat effect is mainly caused by arterial aging. WCH carries higher risk for cardiovascular mortality than PH, probably via enhanced wave reflections that accompany arterial aging.

Propagation of Pressure Waves, Caused by a Thermal Shock, in Liquid Metals Containing Gas Bubbles

NASA Astrophysics Data System (ADS)

Okita, Kohei; Takagi, Shu; Matsumoto, Yoichiro

The propagation of pressure waves caused by a thermal shock in liquid mercury containing micro gas bubbles has been simulated numerically. In the present study, we clarify the influences of the introduced bubble size and void fraction on the absorption of thermal expansion of liquid mercury and attenuation of pressure waves. The mass, momentum and energy conservation equations for both bubbly mixture and gas inside each bubble are solved, in which the bubble dynamics is represented by the Keller equation. The results show that when the initial void fraction is larger than the rate of the thermal expansion of liquid mercury, the pressure rise caused by the thermal expansion decreases with decreasing the bubble radius, because of the increase of the natural frequency of bubbly mixture. On the other hand, as the bubble radius increases, the peak of pressure waves which propagate at the sound speed of mixture decreases gradually due to the dispersion effect of mixture. When the natural frequency of the mixture with large bubbles is lower than that of the thremal shock, the peak pressure at the wall increases because the pressure waves propagate through the mixture at the sound speed of liquid mercury. The comparison of the results with and without heat transfer through the gas liquid interface shows that the pressure waves are attenuated greatly by the thermal damping effect with the decrease of the void fraction which enhances the nonlinearity of bubble oscillation.

Cavitation-based hydro-fracturing simulator

DOEpatents

Wang, Jy-An John; Wang, Hong; Ren, Fei; Cox, Thomas S.

2016-11-22

An apparatus 300 for simulating a pulsed pressure induced cavitation technique (PPCT) from a pressurized working fluid (F) provides laboratory research and development for enhanced geothermal systems (EGS), oil, and gas wells. A pump 304 is configured to deliver a pressurized working fluid (F) to a control valve 306, which produces a pulsed pressure wave in a test chamber 308. The pulsed pressure wave parameters are defined by the pump 304 pressure and control valve 306 cycle rate. When a working fluid (F) and a rock specimen 312 are included in the apparatus, the pulsed pressure wave causes cavitation to occur at the surface of the specimen 312, thus initiating an extensive network of fracturing surfaces and micro fissures, which are examined by researchers.

Cavitation clouds created by shock scattering from bubbles during histotripsy

PubMed Central

Maxwell, Adam D.; Wang, Tzu-Yin; Cain, Charles A.; Fowlkes, J. Brian; Sapozhnikov, Oleg A.; Bailey, Michael R.; Xu, Zhen

2011-01-01

Histotripsy is a therapy that focuses short-duration, high-amplitude pulses of ultrasound to incite a localized cavitation cloud that mechanically breaks down tissue. To investigate the mechanism of cloud formation, high-speed photography was used to observe clouds generated during single histotripsy pulses. Pulses of 5−20 cycles duration were applied to a transparent tissue phantom by a 1-MHz spherically focused transducer. Clouds initiated from single cavitation bubbles that formed during the initial cycles of the pulse, and grew along the acoustic axis opposite the propagation direction. Based on these observations, we hypothesized that clouds form as a result of large negative pressure generated by the backscattering of shockwaves from a single bubble. The positive-pressure phase of the wave inverts upon scattering and superimposes on the incident negative-pressure phase to create this negative pressure and cavitation. The process repeats with each cycle of the incident wave, and the bubble cloud elongates toward the transducer. Finite-amplitude propagation distorts the incident wave such that the peak-positive pressure is much greater than the peak-negative pressure, which exaggerates the effect. The hypothesis was tested with two modified incident waves that maintained negative pressure but reduced the positive pressure amplitude. These waves suppressed cloud formation which supported the hypothesis. PMID:21973343

Observations of wave-induced pore pressure gradients and bed level response on a surf zone sandbar

NASA Astrophysics Data System (ADS)

Anderson, Dylan; Cox, Dan; Mieras, Ryan; Puleo, Jack A.; Hsu, Tian-Jian

2017-06-01

Horizontal and vertical pressure gradients may be important physical mechanisms contributing to onshore sediment transport beneath steep, near-breaking waves in the surf zone. A barred beach was constructed in a large-scale laboratory wave flume with a fixed profile containing a mobile sediment layer on the crest of the sandbar. Horizontal and vertical pore pressure gradients were obtained by finite differences of measurements from an array of pressure transducers buried within the upper several centimeters of the bed. Colocated observations of erosion depth were made during asymmetric wave trials with wave heights between 0.10 and 0.98 m, consistently resulting in onshore sheet flow sediment transport. The pore pressure gradient vector within the bed exhibited temporal rotations during each wave cycle, directed predominantly upward under the trough and then rapidly rotating onshore and downward as the wavefront passed. The magnitude of the pore pressure gradient during each phase of rotation was correlated with local wave steepness and relative depth. Momentary bed failures as deep as 20 grain diameters were coincident with sharp increases in the onshore-directed pore pressure gradients, but occurred at horizontal pressure gradients less than theoretical critical values for initiation of the motion for compact beds. An expression combining the effects of both horizontal and vertical pore pressure gradients with bed shear stress and soil stability is used to determine that failure of the bed is initiated at nonnegligible values of both forces.