Unsteady Full Annulus Simulations of a Transonic Axial Compressor Stage

NASA Technical Reports Server (NTRS)

Herrick, Gregory P.; Hathaway, Michael D.; Chen, Jen-Ping

2009-01-01

Two recent research endeavors in turbomachinery at NASA Glenn Research Center have focused on compression system stall inception and compression system aerothermodynamic performance. Physical experiment and computational research are ongoing in support of these research objectives. TURBO, an unsteady, three-dimensional, Navier-Stokes computational fluid dynamics code commissioned and developed by NASA, has been utilized, enhanced, and validated in support of these endeavors. In the research which follows, TURBO is shown to accurately capture compression system flow range-from choke to stall inception-and also to accurately calculate fundamental aerothermodynamic performance parameters. Rigorous full-annulus calculations are performed to validate TURBO s ability to simulate the unstable, unsteady, chaotic stall inception process; as part of these efforts, full-annulus calculations are also performed at a condition approaching choke to further document TURBO s capabilities to compute aerothermodynamic performance data and support a NASA code assessment effort.

Project Turnover Deliverables for the SY Farm Enraf Annulus Leak Detectors

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

SCAIEF, C.C.

2000-09-19

This document identifies the deliverables that ensure the end user of the SY Farm Enraf Annulus Leak Detectors (ALD) has all the documentation and training required for operating and maintaining the new system. All deliverable items checked on the Acceptance For Beneficial Use (ABU) form have been completed and are available to the end user. This document was written as required by HNF-IP-0842, Volume IV section 3.12 Acceptance of Structures, Systems, and Components for Beneficial Use. This document applies to the deliverable documentation required to operate and maintain the SY Farm Enraf ALD System. Appendix A provides a copy ofmore » the ABU form as listed in the appendix of TWR-4092, Engineering Task Plan for the New SY Farm Annulus Leak Detectors. This document attests that all required deliverable items checked on the ABU have been completed and are available to the end user.« less

Extraordinary acoustic transmission through annuluses in air and its applications in acoustic beam splitter and concentrator

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

Ge, Yong; Liu, Shu-sen; Yuan, Shou-qi, E-mail: Shouqiy@ujs.edu.cn

We report an extraordinary acoustic transmission through two layer annuluses made of metal cylinders in air both numerically and experimentally. The effect arises from the enhancement and reconstruction of the incident source induced by different Mie-resonance modes of the annuluses. The proposed system takes advantages of the consistency in the waveform between the input and output waves, the high amplitude amplification of output waves, and the easy adjustment of structure. More interestingly, we investigate the applications of the extraordinary acoustic transmission in the acoustic beam splitter and acoustic concentrator. Our finding should have an impact on ultrasonic applications.

A multiscale structural investigation of the annulus-endplate anchorage system and its mechanisms of failure.

PubMed

Rodrigues, Samantha A; Thambyah, Ashvin; Broom, Neil D

2015-03-01

The annulus-endplate anchorage system performs a critical role in the disc, creating a strong structural link between the compliant annulus and the rigid vertebrae. Endplate failure is thought to be associated with disc herniation, a recent study indicating that this failure mode occurs more frequently than annular rupture. The aim was to investigate the structural principles governing annulus-endplate anchorage and the basis of its strength and mechanisms of failure. Loading experiments were performed on ovine lumbar motion segments designed to induce annulus-endplate failure, followed by macro- to micro- to fibril-level structural analyses. The study was funded by a doctoral scholarship from our institution. Samples were loaded to failure in three modes: torsion using intact motion segments, in-plane tension of the anterior annulus-endplate along one of the oblique fiber angles, and axial tension of the anterior annulus-endplate. The anterior region was chosen for its ease of access. Decalcification was used to investigate the mechanical influence of the mineralized component. Structural analysis was conducted on both the intact and failed samples using differential interference contrast optical microscopy and scanning electron microscopy. Two main modes of anchorage failure were observed--failure at the tidemark or at the cement line. Samples subjected to axial tension contained more tidemark failures compared with those subjected to torsion and in-plane tension. Samples decalcified before testing frequently contained damage at the cement line, this being more extensive than in fresh samples. Analysis of the intact samples at their anchorage sites revealed that annular subbundle fibrils penetrate beyond the cement line to a limited depth and appear to merge with those in the vertebral and cartilaginous endplates. Annulus-endplate anchorage is more vulnerable to failure in axial tension compared with both torsion and in-plane tension and is probably due to acute fiber bending at the soft-hard interface of the tidemark. This finding is consistent with evidence showing that flexion, which induces a similar pattern of axial tension, increases the risk of herniation involving endplate failure. The study also highlights the important strengthening role of calcification at this junction and provides new evidence of a fibril-based form of structural integration across the cement line. Copyright © 2015 Elsevier Inc. All rights reserved.

Discovery of the First Leaking Double-Shell Tank - Hanford Tank 241-AY-102

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

Harrington, Stephanie J.; Sams, Terry L.

Full text - Long Abstract. A routine video inspection of the annulus region of double-shell tank 241-A Y-102 in August of 2012 indicated the presence material in the annulus space between the primary and secondary liners. A comparison was made to previous inspections performed in 2006 and 2007. which indicated that a change had occurred. The material was observed at two locations on the floor of the annulus and one location at the top of the annulus region where the primary and secondary top knuckles meet (RPP-ASMT-53793). Subsequent inspections were performed. leading to additional material observed on the floor ofmore » the annulus space in a region that had not previously been inspected (WRPS-PER-2012-1363). The annulus Continuous Air Monitor (CAM) was still operational and was not indicating elevated radiation levels in the annulus region. When the camera from the inspections was recovered. it also did not indicate increased radiation above minimum contamination levels (WRPS-PER-2012-1363). A formal leak assessment team was established August 10, 2012 to review tank 241-AY-102 construction and operating histories and to determine whether the material observed in the annulus had resulted from a leak in the primary tank. The team consisted of individuals from Engineering. Base Operations and Environmental Protection. As this was a first-of-its-kind task. a method for obtaining a sample of the material in the annulus was needed. The consistency of the material was unknown.and the location of a majority of the material was not conducive to using the sampling devices that were currently available at Hanford. A subcontractor was tasked with the development fabrication.and testing of a sampling device that would be able to obtain multiple samples from the material on the annulus floor. as well as the material originating from a refractory air-slot near the floor of the annulus space. This sampler would need to be able to collect and dispense the material it collected into a sample jar retrieval device for transportation of the material to the 222-S laboratory on the Hanford site for analysis. The subcontractor agency fabricated a remote underground sampler by modifying off-the-shelf robotics and parts. Limited testing of the sampler was conducted using a mock-up of the tank annulus and one simulated material type -a salt block. The mock-up testing indicated that the sampler would be able to maneuver within the confined space and that the device worked with full functionality. A total of six weeks had passed from initiation to implementation of the new sampler in the 241-AY-102 tank annulus. Initial sample material was obtained from the annulus floor using the Off-Riser Sampler System that has been used at Hanford tor years to obtain material from the primary tanks. This could be used at the location near Riser 83 since the material was collected directly from the annulus floor and not from a location on the wall or behind a pipe, as was needed from the two locations near Riser 90. After obtaining a small sample of the material on the annulus floor.this sampler sustained terminal damage due to conduit pipes it had to transverse in order to collect and recover material from this location. Several issues were also encountered during deployment of the new sampler into the annulus near Riser 90. These included: Difficulty fitting the sampler down the 12-inch riser into the annulus due to a small tolerance in the size of the sampler; Failure of sampler components and functions during deployment including the camera. pneumatics.and bearing seals; Delays in the field due to supporting equipment issues including cables. cameras. and scaffolding; and, Low recovery of sample material obtained for analysis. The complications that occurred during deployment and use of the new sampler during the sampling event ultimately resulted in lower recovery of material from these locations in the annulus than was obtained using the Off-Riser Sampler System and limited the analyses that could be performed for determining the origin of the material. Following completion of the sample analyses and the assessment of its construction history and use. there was a consensus among the leak assessment team members that two of the three materials sampled from the annulus floor region were the result of waste leaking from a breach in the primary tank. The probable leak cause was identified as corrosion at high temperatures in a tank whose containment margins had been reduced due to construction difficulties (RPP-ASMT-53793). A formal Lessons Learned was created concerning designing equipment tor unique purposes under time constraints. This document was published in OPEXShare on May 20. 2013. It highlighted some of the issues that arose with the subcontractor sampler development and provided recommendations to prevent a recurrence should this task need to be performed again in the future. The document can be found at http://msa.hanford.gov/opex/lesson.cfm/2013/5/20/3481/AY-102-Annulus-Sampler-Designing-Equipment-for-Unique-Purposes-under-Time-Constraints/.« less

Annulus fibrosus of the mitral valve: reality or myth.

PubMed

Berdajs, Denis; Zünd, Gregor; Camenisch, Colette; Schurr, Ulrich; Turina, Marko I; Genoni, Michele

2007-01-01

Surgical repair of the mitral valve is in most cases limited to the posterior leaflet of the mitral valve and to the annulus fibrosus. The term annulus fibrosus is still used in anatomical and clinical terminology and is described as a cord like structure providing the attachment of the mitral vale. However, to date no evidence exists of a ring-or cord-like structure at this area. Herein, we describe the attachment of the mitral valve by using the macroscopical and microscopical techniques. The ventricular attachment of the posterior mitral valve leaflet was investigated in 10 human hearts. In dry dissected specimens, the intraventricular illumination was used to identify the attachment of the mitral valve to the left ventricular muscle. Using the histological techniques, we verified the position of the annulus fibrosus. The attachment of the posterior mitral valve leaflet is a band-like structure positioned between the left ventricular muscle and the left atrium. This fibrous band illustrates the morphological attachment of the mitral valve and, as thus, was interpreted as the annulus fibrosus of the mitral valve. Based on our data, no ring-like structure was found corresponding to the anatomical description of the annulus fibrosus, instead the band-like fibrous tissue was identified positioned between the mitral valve and the left ventricle. Histologicaly, we detected that this structure is part of the greater structural system that is directly connected to the membranous septum, to the left and right fibrous trigone and the attachment aortic root to the left ventricular muscle.

Nuclear reactor sealing system

DOEpatents

McEdwards, James A.

1983-01-01

A liquid metal-cooled nuclear reactor sealing system. The nuclear reactor includes a vessel sealed at its upper end by a closure head. The closure head comprises at least two components, one of which is rotatable; and the two components define an annulus therebetween. The sealing system includes at least a first and second inflatable seal disposed in series in an upper portion of the annulus. The system further includes a dip seal extending into a body of insulation located adjacent a bottom portion of the closure head. The dip seal comprises a trough formed by a lower portion of one of the components, and a seal blade pendently supported from the other component and extending downwardly into the trough. A body of liquid metal is contained in the trough which submerges a portion of the seal blade. The seal blade is provided with at least one aperture located above the body of liquid metal for providing fluid communication between the annulus intermediate the dip seal and the inflatable seals, and a body of cover gas located inside the vessel. There also is provided means for introducing a purge gas into the annulus intermediate the inflatable seals and the seal blade. The purge gas is introduced in an amount sufficient to substantially reduce diffusion of radioactive cover gas or sodium vapor up to the inflatable seals. The purge gas mixes with the cover gas in the reactor vessel where it can be withdrawn from the vessel for treatment and recycle to the vessel.

Scattering of circumferential waves in a cracked annulus

NASA Astrophysics Data System (ADS)

Valle, Christine; Qu, Jianmin; Jacobs, Laurence J.

2000-05-01

This paper considers guided waves propagating in the circumferential direction of an annulus with a radial crack, with the objective of developing an ultrasonic technique that can detect and characterize these cracks. Specifically, the finite element method is used to simulate the propagation and scattering of guided circumferential waves in a cracked annulus. This method fosters a better understanding of the wave fields, so that a transducer configuration used in the field can be optimized for crack detection/characterization. Both a point source (simulating laser generated ultrasound) and a distributed source (simulating a PZT transducer) are modeled and compared to corresponding experimental results. Animations (snapshots at different instants in time) of the strain energy field in the annulus are given for various combinations of load profiles, incident angles, and incident frequencies. Results of this paper provide the necessary design guidelines for developing nondestructive ultrasonic techniques for the detection/characterization of radial cracks in cylindrical pressure vessels, gas/oil pipes, and shaft/bearing systems.

Effects of a 3D segmental prosthetic system for tricuspid valve annulus remodelling on the right coronary artery: a human cadaveric coronary angiography study.

PubMed

Riki-Marishani, Mohsen; Gholoobi, Arash; Sazegar, Ghasem; Aazami, Mathias H; Hedjazi, Aria; Sajjadian, Maryam; Ebrahimi, Mahmoud; Aghaii-Zade Torabi, Ahmad

2017-09-01

A prosthetic system to repair secondary tricuspid valve regurgitation was developed. The conceptual engineering of the current device is based on 3D segmental remodelling of the tricuspid valve annulus in lieu of reductive annuloplasty. This study was designed to investigate the operational safety of the current prosthetic system with regard to the anatomical integrity of the right coronary artery (RCA) in fresh cadaveric human hearts. During the study period, from January to April 2016, the current prosthetic system was implanted on the tricuspid valve annulus in fresh cadaveric human hearts that met the study's inclusion criteria. The prepared specimens were investigated via selective coronary angiography of the RCA in the catheterization laboratory. The RCA angiographic anatomies were categorized as normal, distorted, kinked or occluded. Sixteen specimens underwent implantation of the current prosthetic system. The mean age of the cadaveric human hearts was 43.24 ± 15.79 years, with vehicle accident being the primary cause of death (59%). A dominant RCA was noticed in 62.5% of the specimens. None of the specimens displayed any injury, distortion, kinking or occlusion in the RCA due to the implantation of the prostheses. In light of the results of the present study, undertaken on fresh cadaveric human heart specimens, the current segmental prosthetic system for 3D remodelling of the tricuspid valve annulus seems to be safe vis-à-vis the anatomical integrity of the RCA. Further in vivo studies are needed to investigate the functional features of the current prosthetic system with a view to addressing the complex pathophysiology of secondary tricuspid valve regurgitation. © The Author 2017. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

Duct flow nonuniformities: Effect of struts in SSME HGM II(+)

NASA Technical Reports Server (NTRS)

Burke, Roger

1988-01-01

A numerical study, using the INS3D flow solver, of laminar and turbulent flow around a two dimensional strut, and three dimensional flow around a strut in an annulus is presented. A multi-block procedure was used to calculate two dimensional laminar flow around two struts in parallel, with each strut represented by one computational block. Single block calculations were performed for turbulent flow around a two dimensional strut, using a Baldwin-Lomax turbulence model to parameterize the turbulent shear stresses. A modified Baldwin-Lomax model was applied to the case of a three dimensional strut in an annulus. The results displayed the essential features of wing-body flows, including the presence of a horseshoe vortex system at the junction of the strut and the lower annulus surface. A similar system was observed at the upper annulus surface. The test geometries discussed were useful in developing the capability to perform multiblock calculations, and to simulate turbulent flow around obstructions located between curved walls. Both of these skills will be necessary to model the three dimensional flow in the strut assembly of the SSME. Work is now in progress on performing a three dimensional two block turbulent calculation of the flow in the turnaround duct (TAD) and strut/fuel bowl juncture region.

Core disruptive accident margin seal

DOEpatents

Garin, John; Belsick, James C.

1978-01-01

An apparatus for sealing the annulus defined between a substantially cylindrical rotatable first riser assembly and plug combination disposed in a substantially cylindrical second riser assembly and plug combination of a nuclear reactor system. The apparatus comprises a flexible member disposed between the first and second riser components and attached to a metal member which is attached to an actuating mechanism. When the actuating mechanism is not actuated, the flexible member does not contact the riser components thus allowing the free rotation of the riser components. When desired, the actuating mechanism causes the flexible member to contact the first and second riser components in a manner to block the annulus defined between the riser components, thereby sealing the annulus between the riser components.

The extent of aortic annulus calcification is a predictor of postprocedural eccentricity and paravalvular regurgitation: a pre- and postinterventional cardiac computed tomography angiography study.

PubMed

Bekeredjian, Raffi; Bodingbauer, Dorothea; Hofmann, Nina P; Greiner, Sebastian; Schuetz, Moritz; Geis, Nicolas A; Kauczor, Hans U; Bryant, Mark; Chorianopoulos, Emmanuel; Pleger, Sven T; Mereles, Derliz; Katus, Hugo A; Korosoglou, Grigorios

2015-03-01

To investigate if the extent of aortic valve calcification is associated with postprocedural prosthesis eccentricity and paravalvular regurgitation (PAR) in patients undergoing transcatheter aortic valve implantation (TAVI). Cardiac computed tomography angiography (CCTA) was performed before and 3 months after TAVI in 46 patients who received the self-expanding CoreValve and in 22 patients who underwent balloon-expandable Edwards Sapien XT implantation. Aortic annulus calcification was measured with CCTA prior to TAVI and prosthesis eccentricity was assessed with post-TAVI CCTA. Standard echocardiography was also performed in all patients at 3-month follow-up exam. Annulus eccentricity was reduced during TAVI using both implantation systems (from 0.23 ± 0.06 to 0.18 ± 0.07 using CoreValve and from 0.20 ± 0.07 to 0.05 ± 0.03 using Edwards Sapien XT; P<.001 for both). With Edwards Sapien XT, eccentricity reduction at the level of the aortic annulus was significantly higher compared with CoreValve (P<.001). Annulus eccentricity after CoreValve use was significantly related to absolute valve calcification and to valve calcification indexed to body surface area (BSA) (r = 0.48 and 0.50, respectively; P<.001 for both). Furthermore, a significant association was observed between aortic valve calcification and PAR (P<.01 by ANOVA) in patients who received CoreValve. Using ROC analysis, a cut-off value over 913 mm² aortic valve calcification predicted the occurrence of moderate or severe PAR with a sensitivity of 92% and a specificity of 63% (area under the curve = 0.75). Furthermore, multivariable analysis showed that aortic valve calcification was a robust predictor of postprocedural eccentricity and PAR, independent of the aortic annulus size and native valve eccentricity and of CoreValve prosthesis size (adjusted r = 0.46 and 0.50, respectively; P<.01 for both). Such associations were not present with the Edwards Sapien XT system. The extent of native aortic annulus calcification is predictive for postprocedural prosthesis eccentricity and PAR, which is an important marker for long-term mortality in patients undergoing TAVI. This observation applies for the CoreValve, but not for the Edwards Sapien XT valve.

GEOSIM: A numerical model for geophysical fluid flow simulation

NASA Technical Reports Server (NTRS)

Butler, Karen A.; Miller, Timothy L.; Lu, Huei-Iin

1991-01-01

A numerical model which simulates geophysical fluid flow in a wide range of problems is described in detail, and comparisons of some of the model's results are made with previous experimental and numerical studies. The model is based upon the Boussinesq Navier-Stokes equations in spherical coordinates, which can be reduced to a cylindrical system when latitudinal walls are used near the pole and the ratio of latitudinal length to the radius of the sphere is small. The equations are approximated by finite differences in the meridional plane and spectral decomposition in the azimuthal direction. The user can specify a variety of boundary and initial conditions, and there are five different spectral truncation options. The results of five validation cases are presented: (1) the transition between axisymmetric flow and baroclinic wave flow in the side heated annulus; (2) the steady baroclinic wave of the side heated annulus; (3) the wave amplitude vacillation of the side heated annulus; (4) transition to baroclinic wave flow in a bottom heated annulus; and (5) the Spacelab Geophysical Fluid Flow Cell (spherical) experiment.

Flow regimes in a shallow rotating cylindrical annulus with temperature gradients imposed on the horizontal boundaries

NASA Technical Reports Server (NTRS)

Hathaway, D. H.; Fowlis, W. W.

1986-01-01

Experimental flow regime diagrams are determined for a new rotating cylindrical annulus configuration which permits a measure of control over the internal vertical temperature gradient. The new annulus has radial temperature gradients imposed on plane horizontal thermally conducting endwalls (with the cylindrical sidewalls as insulators) and is considered to be more relevant to atmospheric dynamics studies than the classical cylindrical annulus. Observations have revealed that, in addition to the axisymmetric flow and nonaxisymmetric baroclinic wave flow which occur in the classical annulus, two additional nonaxisymmetric flow types occur in the new annulus: boundary-layer thermal convection and deep thermal convection. Flow regime diagrams for three different values of the imposed vertical temperature difference are presented, and explanations for the flow transitions are offered. The new annulus provides scientific backup for the proposed Atmospheric General Circulation Experiment for Spacelab. The apparatus diagram is included.

Mitral valve morphology assessed by three-dimensional transthoracic echocardiography in healthy dogs and dogs with myxomatous mitral valve disease.

PubMed

Menciotti, G; Borgarelli, M; Aherne, M; Wesselowski, S; Häggström, J; Ljungvall, I; Lahmers, S M; Abbott, J A

2017-04-01

To assess differences in morphology of the mitral valve (MV) between healthy dogs and dogs affected by myxomatous mitral valve disease (MMVD) using real-time transthoracic three-dimensional echocardiography (RT3DE). Thirty-four were normal dogs and 79 dogs were affected by MMVD. Real-time transthoracic three-dimensional echocardiography mitral datasets were digitally recorded and analyzed using dedicated software. The following variables were obtained and compared between healthy dogs and dogs with MMVD at different stages: antero-posterior annulus diameter, anterolateral-posteromedial annulus diameter, commissural diameter, annulus height, annulus circumference, annulus area, anterior leaflet length, anterior leaflet area, posterior leaflet length, posterior leaflet area, non-planar angle, annulus sphericity index, tenting height, tenting area, tenting volume, the ratio of annulus height and commissural diameter. Dogs with MMVD had a more circular MV annulus compared to healthy dogs as demonstrated by an increased annulus sphericity index (p=0.0179). Affected dogs had a less saddle-shaped MV manifest as a decreased annulus height to commissural width ratio (p=0.0004). Tenting height (p<0.0001), area (p<0.0001), and volume (p<0.0001) were less in affected dogs. Real-time transthoracic three-dimensional echocardiography analysis demonstrated that dogs affected by MMVD had a more circular and less saddle-shaped MV annulus, as well as reduced tenting height area and volume, compared to healthy dogs. Multiple variables differed between dogs at different stages of MMVD. Diagnostic and prognostic utility of these variables, and the significance of these changes in the pathogenesis and natural history of MMVD, require further attention. Copyright © 2017 Elsevier B.V. All rights reserved.

Radiation and viscous dissipation effect on square porous annulus

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

Badruddin, Irfan Anjum; Quadir, G. A.

The present study is carried out to investigate the effect of radiation and viscous dissipation in a square porous annulus subjected to outside hot T{sub h} and inside cold T{sub c} temperature. The square annulus has a hollow section of dimension D×D at the interior of annulus. The flow is assumed to obey Darcy law. The governing equations are non-dimensionalised and solved with the help of finite element method. Results are discussed with respect to viscous dissipation parameter, radiation parameter and size of the hollow section of annulus.

Potential risk for bacterial contamination in conventional reused ventilator systems and disposable closed ventilator-suction systems.

PubMed

Li, Ya-Chi; Lin, Hui-Ling; Liao, Fang-Chun; Wang, Sing-Siang; Chang, Hsiu-Chu; Hsu, Hung-Fu; Chen, Sue-Hsien; Wan, Gwo-Hwa

2018-01-01

Few studies have investigated the difference in bacterial contamination between conventional reused ventilator systems and disposable closed ventilator-suction systems. The aim of this study was to investigate the bacterial contamination rates of the reused and disposable ventilator systems, and the association between system disconnection and bacterial contamination of ventilator systems. The enrolled intubated and mechanically ventilated patients used a conventional reused ventilator system and a disposable closed ventilator-suction system, respectively, for a week; specimens were then collected from the ventilator circuit systems to evaluate human and environmental bacterial contamination. The sputum specimens from patients were also analyzed in this study. The detection rate of bacteria in the conventional reused ventilator system was substantially higher than that in the disposable ventilator system. The inspiratory and expiratory limbs of the disposable closed ventilator-suction system had higher bacterial concentrations than the conventional reused ventilator system. The bacterial concentration in the heated humidifier of the reused ventilator system was significantly higher than that in the disposable ventilator system. Positive associations existed among the bacterial concentrations at different locations in the reused and disposable ventilator systems, respectively. The predominant bacteria identified in the reused and disposable ventilator systems included Acinetobacter spp., Bacillus cereus, Elizabethkingia spp., Pseudomonas spp., and Stenotrophomonas (Xan) maltophilia. Both the reused and disposable ventilator systems had high bacterial contamination rates after one week of use. Disconnection of the ventilator systems should be avoided during system operation to decrease the risks of environmental pollution and human exposure, especially for the disposable ventilator system. ClinicalTrials.gov PRS / NCT03359148.

Mitral annulus size links ventricular dilatation to functional mitral regurgitation.

PubMed

Popović, Zoran B; Martin, Maureen; Fukamachi, Kiyotaka; Inoue, Masahiro; Kwan, Jun; Doi, Kazuyoshi; Qin, Jian Xin; Shiota, Takahiro; Garcia, Mario J; McCarthy, Patrick M; Thomas, James D

2005-09-01

We compared the impact of annulus size and valve deformation (tethering) on mitral regurgitation in the animal dilated cardiomyopathy model, and assessed if acute left ventricular volume changes affect mitral annulus dimensions. We performed 3-dimensional echocardiography in 30 open-chest dogs with pacing-induced cardiomyopathy. Mitral annulus area was calculated from its two orthogonal diameters, whereas valve tethering was quantified by valve tenting area measurement. Mitral valve regurgitant volume showed the highest correlation with annulus area (r = 0.64, P < .001), left atrial volume (r = 0.40, P < .01), and left ventricular end-diastolic volume (r = 0.37, P < .01). Regurgitant volume showed poorer correlation with valve tethering in both septolateral and intercommissural planes (r = 0.35 and r = 0.31, P < .05 for both). Annulus dimensions correlated with acute changes of left ventricular end-diastolic volume (r = 0.68, P = .002). Mitral annulus dilation is the strongest predictor of functional mitral regurgitation in this animal dilated cardiomyopathy model.

Bifurcation of Limit Cycles in a Near-Hamiltonian System with a Cusp of Order Two and a Saddle

NASA Astrophysics Data System (ADS)

Bakhshalizadeh, Ali; Zangeneh, Hamid R. Z.; Kazemi, Rasool

In this paper, the asymptotic expansion of first-order Melnikov function of a heteroclinic loop connecting a cusp of order two and a hyperbolic saddle for a planar near-Hamiltonian system is given. Next, we consider the limit cycle bifurcations of a hyper-elliptic Liénard system with this kind of heteroclinic loop and study the least upper bound of limit cycles bifurcated from the period annulus inside the heteroclinic loop, from the heteroclinic loop itself and the center. We find that at most three limit cycles can be bifurcated from the period annulus, also we present different distributions of bifurcated limit cycles.

Potential risk for bacterial contamination in conventional reused ventilator systems and disposable closed ventilator-suction systems

PubMed Central

Li, Ya-Chi; Lin, Hui-Ling; Liao, Fang-Chun; Wang, Sing-Siang; Chang, Hsiu-Chu; Hsu, Hung-Fu; Chen, Sue-Hsien

2018-01-01

Background Few studies have investigated the difference in bacterial contamination between conventional reused ventilator systems and disposable closed ventilator-suction systems. The aim of this study was to investigate the bacterial contamination rates of the reused and disposable ventilator systems, and the association between system disconnection and bacterial contamination of ventilator systems. Methods The enrolled intubated and mechanically ventilated patients used a conventional reused ventilator system and a disposable closed ventilator-suction system, respectively, for a week; specimens were then collected from the ventilator circuit systems to evaluate human and environmental bacterial contamination. The sputum specimens from patients were also analyzed in this study. Results The detection rate of bacteria in the conventional reused ventilator system was substantially higher than that in the disposable ventilator system. The inspiratory and expiratory limbs of the disposable closed ventilator-suction system had higher bacterial concentrations than the conventional reused ventilator system. The bacterial concentration in the heated humidifier of the reused ventilator system was significantly higher than that in the disposable ventilator system. Positive associations existed among the bacterial concentrations at different locations in the reused and disposable ventilator systems, respectively. The predominant bacteria identified in the reused and disposable ventilator systems included Acinetobacter spp., Bacillus cereus, Elizabethkingia spp., Pseudomonas spp., and Stenotrophomonas (Xan) maltophilia. Conclusions Both the reused and disposable ventilator systems had high bacterial contamination rates after one week of use. Disconnection of the ventilator systems should be avoided during system operation to decrease the risks of environmental pollution and human exposure, especially for the disposable ventilator system. Trial registration ClinicalTrials.gov PRS / NCT03359148 PMID:29547638

Two-phase/two-phase heat exchanger simulation analysis

NASA Technical Reports Server (NTRS)

Kim, Rhyn H.

1992-01-01

The capillary pumped loop (CPL) system is one of the most desirable devices to dissipate heat energy in the radiation environment of the Space Station providing a relatively easy control of the temperature. A condenser, a component of the CPL system, is linked with a buffer evaporator in the form of an annulus section of a double tube heat exchanger arrangement: the concentric core of the double tube is the condenser; the annulus section is used as a buffer between the conditioned space and the radiation surrounding but works as an evaporator. A CPL system with this type of condenser is modeled to simulate its function numerically. Preliminary results for temperature variations of the system are shown and more investigations are suggested for further improvement.

Difference in Energy Metabolism of Annulus Fibrosus and Nucleus Pulposus Cells of the Intervertebral Disc

PubMed Central

Salvatierra, Jessica Czamanski; Yuan, Tai Yi; Fernando, Hanan; Castillo, Andre; Gu, Wei Yong; Cheung, Herman S.; Huant, C.-Y. Charles

2011-01-01

Low back pain is associated with intervertebral disc degeneration. One of the main signs of degeneration is the inability to maintain extracellular matrix integrity. Extracellular matrix synthesis is closely related to production of adenosine triphosphate (i.e. energy) of the cells. The intervertebral disc is composed of two major anatomical regions: annulus fibrosus and nucleus pulposus, which are structurally and compositionally different, indicating that their cellular metabolisms may also be distinct. The objective of this study was to investigate energy metabolism of annulus fibrosus and nucleus pulposus cells with and without dynamic compression, and examine differences between the two cell types. Porcine annulus and nucleus tissues were harvested and enzymatically digested. Cells were isolated and embedded into agarose constructs. Dynamically loaded samples were subjected to a sinusoidal displacement at 2 Hz and 15% strain for 4 h. Energy metabolism of cells was analyzed by measuring adenosine triphosphate content and release, glucose consumption, and lactate/nitric oxide production. A comparison of those measurements between annulus and nucleus cells was conducted. Annulus and nucleus cells exhibited different metabolic pathways. Nucleus cells had higher adenosine triphosphate content with and without dynamic loading, while annulus cells had higher lactate production and glucose consumption. Compression increased adenosine triphosphate release from both cell types and increased energy production of annulus cells. Dynamic loading affected energy metabolism of intervertebral disc cells, with the effect being greater in annulus cells. PMID:21625336

Modeling mantle convection in the spherical annulus

NASA Astrophysics Data System (ADS)

Hernlund, John W.; Tackley, Paul J.

2008-12-01

Most methods for modeling mantle convection in a two-dimensional (2D) circular annular domain suffer from innate shortcomings in their ability to capture several characteristics of the spherical shell geometry of planetary mantles. While methods such as rescaling the inner and outer radius to reduce anomalous effects in a 2D polar cylindrical coordinate system have been introduced and widely implemented, such fixes may have other drawbacks that adversely affect the outcome of some kinds of mantle convection studies. Here we propose a new approach that we term the "spherical annulus," which is a 2D slice that bisects the spherical shell and is quantitatively formulated at the equator of a spherical polar coordinate system after neglecting terms in the governing equations related to variations in latitude. Spherical scaling is retained in this approximation since the Jacobian function remains proportional to the square of the radius. We present example calculations to show that the behavior of convection in the spherical annulus compares favorably against calculations performed in other 2D annular domains when measured relative to those in a fully three-dimensional (3D) spherical shell.

46 CFR 111.103-1 - Power ventilation systems except machinery space ventilation systems.

Code of Federal Regulations, 2010 CFR

2010-10-01

... (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Remote Stopping Systems § 111.103-1 Power ventilation systems except machinery space ventilation systems. Each power ventilation system must... 46 Shipping 4 2010-10-01 2010-10-01 false Power ventilation systems except machinery space...

46 CFR 111.103-1 - Power ventilation systems except machinery space ventilation systems.

Code of Federal Regulations, 2011 CFR

2011-10-01

... (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Remote Stopping Systems § 111.103-1 Power ventilation systems except machinery space ventilation systems. Each power ventilation system must... 46 Shipping 4 2011-10-01 2011-10-01 false Power ventilation systems except machinery space...

46 CFR 111.103-1 - Power ventilation systems except machinery space ventilation systems.

Code of Federal Regulations, 2014 CFR

2014-10-01

... (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Remote Stopping Systems § 111.103-1 Power ventilation systems except machinery space ventilation systems. Each power ventilation system must... 46 Shipping 4 2014-10-01 2014-10-01 false Power ventilation systems except machinery space...

46 CFR 111.103-1 - Power ventilation systems except machinery space ventilation systems.

Code of Federal Regulations, 2012 CFR

2012-10-01

... (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Remote Stopping Systems § 111.103-1 Power ventilation systems except machinery space ventilation systems. Each power ventilation system must... 46 Shipping 4 2012-10-01 2012-10-01 false Power ventilation systems except machinery space...

46 CFR 111.103-1 - Power ventilation systems except machinery space ventilation systems.

Code of Federal Regulations, 2013 CFR

2013-10-01

... (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Remote Stopping Systems § 111.103-1 Power ventilation systems except machinery space ventilation systems. Each power ventilation system must... 46 Shipping 4 2013-10-01 2013-10-01 false Power ventilation systems except machinery space...

Double-Shell Tank Visual Inspection Changes Resulting from the Tank 241-AY-102 Primary Tank Leak

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

Girardot, Crystal L.; Washenfelder, Dennis J.; Johnson, Jeremy M.

2013-11-14

As part of the Double-Shell Tank (DST) Integrity Program, remote visual inspections are utilized to perform qualitative in-service inspections of the DSTs in order to provide a general overview of the condition of the tanks. During routine visual inspections of tank 241-AY-102 (AY-102) in August 2012, anomalies were identified on the annulus floor which resulted in further evaluations. In October 2012, Washington River Protection Solutions, LLC determined that the primary tank of AY-102 was leaking. Following identification of the tank AY-102 probable leak cause, evaluations considered the adequacy of the existing annulus inspection frequency with respect to the circumstances ofmore » the tank AY-102 1eak and the advancing age of the DST structures. The evaluations concluded that the interval between annulus inspections should be shortened for all DSTs, and each annulus inspection should cover > 95 percent of annulus floor area, and the portion of the primary tank (i.e., dome, sidewall, lower knuckle, and insulating refractory) that is visible from the annulus inspection risers. In March 2013, enhanced visual inspections were performed for the six oldest tanks: 241-AY-101, 241-AZ-101,241-AZ-102, 241-SY-101, 241-SY-102, and 241-SY-103, and no evidence of leakage from the primary tank were observed. Prior to October 2012, the approach for conducting visual examinations of DSTs was to perform a video examination of each tank's interior and annulus regions approximately every five years (not to exceed seven years between inspections). Also, the annulus inspection only covered about 42 percent of the annulus floor.« less

Numerical investigation of heat transfer in annulus laminar flow of multi tubes-in-tube helical coil

NASA Astrophysics Data System (ADS)

Nada, S. A.; Elattar, H. F.; Fouda, A.; Refaey, H. A.

2018-03-01

In the present study, a CFD analysis using ANSYS-FLUENT 14.5 CFD package is used to investigate the characteristics of heat transfer of laminar flow in annulus formed by multi tubes in tube helically coiled heat exchanger. The numerical results are validated by comparison with previous experimental data and fair agreements were existed. The influences of the design and operation parameters such as heat flux, Reynolds numbers and annulus geometry on the heat transfer characteristics are investigated. Different annulus of different numbers of inner tubes, specifically 1, 2, 3, 4 and 5 tubes, are tested. The Results showed that for all the studied annulus, the heat flux has no effect on the Nusselt number and compactness parameter. The annulus formed by using five inner tubes showed the best heat transfer performance and compactness parameter. Correlation of predicting Nusselt number in terms of Reynolds number and number of inner tubes are presented.

A numerical study of natural convection in a vertical annulus filled with gallium in the presence of magnetic field

NASA Astrophysics Data System (ADS)

Afrand, Masoud; Toghraie, Davood; Karimipour, Arash; Wongwises, Somchai

2017-05-01

Presets work aims to investigate the natural convection inside a cylindrical annulus mold containing molten gallium under a horizontal magnetic field in three-dimensional coordinates. The modeling system is a vertical cylindrical annulus which is made by two co-axial cylinders of internal and external radii. The internal and external walls are maintained isothermal but in different temperatures. The upper and lower sides of annulus are also considered adiabatic while it is filled by an electrical conducting fluid. Three dimensional cylindrical coordinates as (r , θ , z) are used to respond the velocity components as (u , v , w) . The governing equations are steady, laminar and Newtonian using the Boussinesq approximation. Equations are nonlinear and they must be corresponded by applying the finite volume approach; so that the hybrid-scheme is applied to discretize equations. The results imply that magnetic field existence leads to generate the Lorentz force in opposite direction of the buoyancy forces. Moreover the Lorentz force and its corresponded electric field are more significant in both Hartmann layer and Roberts layer, respectively. The strong magnetic field is required to achieve better quality products in the casting process of a liquid metal with a higher Prandtl number.

ISSLS prize winner: microstructure and mechanical disruption of the lumbar disc annulus: part II: how the annulus fails under hydrostatic pressure.

PubMed

Veres, Samuel P; Robertson, Peter A; Broom, Neil D

2008-12-01

Mechanically induced annular disruption of lumbar intervertebral discs followed by microstructural investigation. To investigate the role that elevated nuclear pressures play in disrupting the lumbar intervertebral disc's annulus fibrosus. Compound mechanical loadings have been used to recreate clinically relevant annular disruptions in vitro. However, the role that individual loading parameters play in disrupting the lumbar disc's annulus remains unclear. The nuclei of ovine lumbar intervertebral discs were gradually pressurized by injecting a viscous radio-opaque gel via their inferior vertebrae. Pressurization was conducted until catastrophic failure of the disc occurred. Investigation of the resulting annular disruption was carried out using microcomputed tomography and differential interference contrast microscopy. Gel extrusion from the posterior annulus was the most common mode of disc failure. Unlike other aspects of the annular wall, the posterior region was unable to distribute hydrostatic pressures circumferentially. In each extrusion case, severe disruption of the posterior annulus occurred. Although intralamellar disruption occurred in the mid annulus, interlamellar disruption occurred in the outer posterior annulus. Radial ruptures between lamellae always occurred in the mid-axial plane. With respect to the annular wall, the posterior region is most susceptible to failure in the presence of high nuclear pressure, even when loaded in the neutral position. Weak interlamellar cohesion of the outer posterior lamellae may explain why the majority of herniations remain contained as protrusions within the outer annular wall.

Unexpected delayed complete atrioventricular block after Cardioband implantation.

PubMed

Sorini Dini, Carlotta; Landi, Daniele; Meucci, Francesco; Di Mario, Carlo

2018-03-06

The Cardioband system is a transcatheter direct annuloplasty device that is implanted in patients with severe symptomatic functional mitral regurgitation (MR) due to annulus dilatation and high surgical risk. This device covers the posterior two-thirds of the annulus, from the anterolateral to the posteromedial commissure, implanted in close proximity of the left circumflex artery, atrioventricular (AV) conduction system, and coronary sinus. We present the case of an 80-year-old-gentleman with prohibitive surgical risk, treated with Cardioband implantation for functional MR with an evident P1-P2 cleft and P2-P3 indentation, a relative contraindication to MitraClip implantation. We achieved procedural success with significative mitral annulus reduction (30% anteroposterior reduction from 37 to 26 mm) and MR reduction (from grade 4 to grade 1-2). A late onset Mobitz 2 AV block developed after 26 hr and evolved to complete AV block in the following day, requiring definitive biventricular pacemaker (PM). Less than 200 Cardioband implantations have been performed but, to our knowledge, this is the first reported AV block, possibly facilitated by the pre-existing bifascicular block, suggesting the opportunity of prolonged ECG monitoring after Cardioband like any other mechanical transcatheter structural intervention possibly affecting the AV conduction system. © 2018 Wiley Periodicals, Inc.

Shaft seal system

DOEpatents

Kapich, Davorin D.

1985-01-01

A shaft seal system is disclosed for isolating two regions of different fluid mediums through which a rotatable shaft extends. The seal system includes a seal housing through which the shaft extends and which defines an annular land and an annular labyrinth both of which face on the shaft so that each establishes a corresponding fluid sealing annulus. A collection cavity is formed in communication with the annular sealing spaces, and fluids compatible with the fluids in each of the two regions to be isolated are introduced, respectively, into the annular sealing spaces and collected in the collection cavity from which the fluid mixture is removed and passed to a separator which separates the fluids and returns them to their respective annular sealing spaces in a recycling manner. In the illustrated embodiment, the isolated fluid mediums comprise a liquid region and a gas region. Gas is removed from the gas region and passed through a purifier and a gas pump operative to introduce the purified gas through the labyrinth sealing annulus to the collection cavity. After passing to the separator, the separated gas is passed through a dryer from which the dried gas is caused to pass through the labyrinth sealing annulus into the collection cavity independently of the purified gas so as to insure isolation of the gas region in the event of sealing gas pump malfunction.

A new system for understanding modes of mechanical ventilation.

PubMed

Chatburn, R L; Primiano, F P

2001-06-01

Numerous ventilation modes and ventilation options have become available as new mechanical ventilators have reached the market. Ventilator manufacturers have no standardized terminology for ventilator modes and ventilation options, and ventilator operator's manuals do not help the clinician compare the modes of ventilators from different manufacturers. This article proposes a standardized system for classifying ventilation modes, based on general engineering principles and a small set of explicit definitions. Though there may be resistance by ventilator manufacturers to a standardized system of ventilation terminology, clinicians and health care equipment purchasers should adopt such a system in the interest of clear communication--the lack of which prevents clinicians from fully understanding the therapies they administer and could compromise the quality of patient care.

46 CFR 154.1200 - Mechanical ventilation system: General.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 5 2010-10-01 2010-10-01 false Mechanical ventilation system: General. 154.1200 Section... Equipment Cargo Area: Mechanical Ventilation System § 154.1200 Mechanical ventilation system: General. (a... cargo handling equipment must have a fixed, exhaust-type mechanical ventilation system. (b) The...

Interactive simulation system for artificial ventilation on the internet: virtual ventilator.

PubMed

Takeuchi, Akihiro; Abe, Tadashi; Hirose, Minoru; Kamioka, Koichi; Hamada, Atsushi; Ikeda, Noriaki

2004-12-01

To develop an interactive simulation system "virtual ventilator" that demonstrates the dynamics of pressure and flow in the respiratory system under the combination of spontaneous breathing, ventilation modes, and ventilator options. The simulation system was designed to be used by unexperienced health care professionals as a self-training tool. The system consists of a simulation controller and three modules: respiratory, spontaneous breath, and ventilator. The respiratory module models the respiratory system by three resistances representing the main airway, the right and left lungs, and two compliances also representing the right and left lungs. The spontaneous breath module generates inspiratory negative pressure produced by a patient. The ventilator module generates driving force of pressure or flow according to the combination of the ventilation mode and options. These forces are given to the respiratory module through the simulation controller. The simulation system was developed using HTML, VBScript (3000 lines, 100 kB) and ActiveX control (120 kB), and runs on Internet Explorer (5.5 or higher). The spontaneous breath is defined by a frequency, amplitude and inspiratory patterns in the spontaneous breath module. The user can construct a ventilation mode by setting a control variable, phase variables (trigger, limit, and cycle), and options. Available ventilation modes are: controlled mechanical ventilation (CMV), continuous positive airway pressure, synchronized intermittent mandatory ventilation (SIMV), pressure support ventilation (PSV), SIMV + PSV, pressure-controlled ventilation (PCV), pressure-regulated volume control (PRVC), proportional assisted ventilation, mandatory minute ventilation (MMV), bilevel positive airway pressure (BiPAP). The simulation system demonstrates in a graph and animation the airway pressure, flow, and volume of the respiratory system during mechanical ventilation both with and without spontaneous breathing. We developed a web application that demonstrated the respiratory mechanics and the basic theory of ventilation mode.

46 CFR 154.1205 - Mechanical ventilation system: Standards.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 5 2010-10-01 2010-10-01 false Mechanical ventilation system: Standards. 154.1205... Equipment Cargo Area: Mechanical Ventilation System § 154.1205 Mechanical ventilation system: Standards. (a) Each exhaust type mechanical ventilation system required under § 154.1200 (a) must have ducts for...

241-AZ Farm Annulus Extent of Condition Baseline Inspection

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

Engeman, Jason K.; Girardot, Crystal L.; Vazquez, Brandon J.

2013-05-15

This report provides the results of the comprehensive annulus visual inspection for tanks 241- AZ-101 and 241-AZ-102 performed in fiscal year 2013. The inspection established a baseline covering about 95 percent of the annulus floor for comparison with future inspections. Any changes in the condition are also included in this document.

Instantons in Script N = 2 magnetized D-brane worlds

NASA Astrophysics Data System (ADS)

Billò, Marco; Frau, Marialuisa; Pesando, Igor; Di Vecchia, Paolo; Lerda, Alberto; Marotta, Raffaele

2007-10-01

In a toroidal orbifold of type IIB string theory we study instanton effects in Script N = 2 super Yang-Mills theories engineered with systems of wrapped magnetized D9 branes and Euclidean D5 branes. We analyze the various open string sectors in this brane system and study the 1-loop amplitudes described by annulus diagrams with mixed boundary conditions, explaining their rôle in the stringy instanton calculus. We show in particular that the non-holomorphic terms in these annulus amplitudes precisely reconstruct the appropriate Kähler metric factors that are needed to write the instanton correlators in terms of purely holomorphic variables. We also explicitly derive the correct holomorphic structure of the instanton induced low energy effective action in the Coulomb branch.

Role of Inclined Magnetic Field and Copper Nanoparticles on Peristaltic Flow of Nanofluid through Inclined Annulus: Application of the Clot Model

NASA Astrophysics Data System (ADS)

Shahzadi, Iqra; Nadeem, S.

2017-06-01

A genuine neurotic condition is experienced when some blood constituents accumulate on the wall of the artery get withdrew from the wall, again join the circulatory system and coagulation occur. Role of copper nanoparticles and inclined magnetic field on the peristaltic flow of a nanofluid in an annular region of inclined annulus is investigated. We represent the clot model by considering the small artery as an annulus whose outer tube has a wave of sinusoidal nature and inner tube has a clot on its walls. Lubrication approach is used to simplify the problem. Close form solutions are determined for temperature and velocity profile. Impact of related parameters on pressure rise, pressure gradient, velocity and streamlines are interpreted graphically. Comparison among the pure blood and copper blood is presented and analyzed. One main finding of the considered analysis is that the inclusion of copper nanoparticles enlarges the amplitude of the velocity. Therefore, the considered study plays a dominant role in biomedical applications.

Biomechanical testing of a polymer-based biomaterial for the restoration of spinal stability after nucleotomy

PubMed Central

Hegewald, Aldemar A; Knecht, Sven; Baumgartner, Daniel; Gerber, Hans; Endres, Michaela; Kaps, Christian; Stüssi, Edgar; Thomé, Claudius

2009-01-01

Background Surgery for disc herniations can be complicated by two major problems: painful degeneration of the spinal segment and re-herniation. Therefore, we examined an absorbable poly-glycolic acid (PGA) biomaterial, which was lyophilized with hyaluronic acid (HA), for its utility to (a) re-establish spinal stability and to (b) seal annulus fibrosus defects. The biomechanical properties range of motion (ROM), neutral zone (NZ) and a potential annulus sealing capacity were investigated. Methods Seven bovine, lumbar spinal units were tested in vitro for ROM and NZ in three consecutive stages: (a) intact, (b) following nucleotomy and (c) after insertion of a PGA/HA nucleus-implant. For biomechanical testing, spinal units were mounted on a loading-simulator for spines. In three cycles, axial loading was applied in an excentric mode with 0.5 Nm steps until an applied moment of ± 7.5 Nm was achieved in flexion/extension. ROM and NZ were assessed. These tests were performed without and with annulus sealing by sewing a PGA/HA annulus-implant into the annulus defect. Results Spinal stability was significantly impaired after nucleotomy (p < 0.001). Intradiscal implantation of a PGA-HA nucleus-implant, however, restored spinal stability (p < 0.003). There was no statistical difference between the stability provided by the nucleus-implant and the intact stage regarding flexion/extension movements (p = 0.209). During the testing sequences, herniation of biomaterial through the annulus defect into the spinal canal regularly occurred, resulting in compression of neural elements. Sewing a PGA/HA annulus-implant into the annulus defect, however, effectively prevented herniation. Conclusion PGA/HA biomaterial seems to be well suited for cell-free and cell-based regenerative treatment strategies in spinal surgery. Its abilities to restore spinal stability and potentially close annulus defects open up new vistas for regenerative approaches to treat intervertebral disc degeneration and for preventing implant herniation. PMID:19604373

33 CFR 183.620 - Natural ventilation system.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Natural ventilation system. 183... (CONTINUED) BOATING SAFETY BOATS AND ASSOCIATED EQUIPMENT Ventilation § 183.620 Natural ventilation system. (a) Except for compartments open to the atmosphere, a natural ventilation system that meets the...

33 CFR 183.620 - Natural ventilation system.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Natural ventilation system. 183... (CONTINUED) BOATING SAFETY BOATS AND ASSOCIATED EQUIPMENT Ventilation § 183.620 Natural ventilation system. (a) Except for compartments open to the atmosphere, a natural ventilation system that meets the...

Effects of Mechanical Ventilation on Heart Geometry and Mitral Valve Leaflet Coaptation During Percutaneous Edge-to-Edge Mitral Valve Repair.

PubMed

Patzelt, Johannes; Zhang, Yingying; Seizer, Peter; Magunia, Harry; Henning, Andreas; Riemlova, Veronika; Patzelt, Tara A E; Hansen, Marc; Haap, Michael; Riessen, Reimer; Lausberg, Henning; Walker, Tobias; Reutershan, Joerg; Schlensak, Christian; Grasshoff, Christian; Simon, Dan I; Rosenberger, Peter; Schreieck, Juergen; Gawaz, Meinrad; Langer, Harald F

2016-01-25

This study sought to evaluate a ventilation maneuver to facilitate percutaneous edge-to-edge mitral valve repair (PMVR) and its effects on heart geometry. In patients with challenging anatomy, the application of PMVR is limited, potentially resulting in insufficient reduction of mitral regurgitation (MR) or clip detachment. Under general anesthesia, however, ventilation maneuvers can be used to facilitate PMVR. A total of 50 consecutive patients undergoing PMVR were included. During mechanical ventilation, different levels of positive end-expiratory pressure (PEEP) were applied, and parameters of heart geometry were assessed using transesophageal echocardiography. We found that increased PEEP results in elevated central venous pressure. Specifically, central venous pressure increased from 14.0 ± 6.5 mm Hg (PEEP 3 mm Hg) to 19.3 ± 5.9 mm Hg (PEEP 20 mm Hg; p < 0.001). As a consequence, the reduced pre-load resulted in reduction of the left ventricular end-systolic diameter from 43.8 ± 10.7 mm (PEEP 3 mm Hg) to 39.9 ± 11.0 mm (PEEP 20 mm Hg; p < 0.001), mitral valve annulus anterior-posterior diameter from 32.4 ± 4.3 mm (PEEP 3 mm Hg) to 30.5 ± 4.4 mm (PEEP 20 mm Hg; p < 0.001), and the medio-lateral diameter from 35.4 ± 4.2 mm to 34.1 ± 3.9 mm (p = 0.002). In parallel, we observed a significant increase in leaflet coaptation length from 3.0 ± 0.8 mm (PEEP 3 mm Hg) to 5.4 ± 1.1 mm (PEEP 20 mm Hg; p < 0.001). The increase in coaptation length was more pronounced in MR with functional or mixed genesis. Importantly, a coaptation length >4.9 mm at PEEP of 10 mm Hg resulted in a significant reduction of PMVR procedure time (152 ± 49 min to 116 ± 26 min; p = 0.05). In this study, we describe a novel ventilation maneuver improving mitral valve coaptation length during the PMVR procedure, which facilitates clip positioning. Our observations could help to improve PMVR therapy and could make nonsurgical candidates accessible to PMVR therapy, particularly in challenging cases with functional MR. Copyright © 2016 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Insulator for laser housing

DOEpatents

Duncan, D.B.

1992-12-29

The present invention provides a heat-resistant electrical insulator adapted for joining laser housing portions, which insulator comprises: an annulus; a channel in the annulus traversing the circumference and length of the housing; at least two ports, each communicating with the channel and an outer surface of the housing; and an attachment for securely attaching each end of the annulus to a laser housing member. 3 figs.

Insulator for laser housing

DOEpatents

Duncan, David B.

1992-01-01

The present invention provides a heat-resistant electrical insulator adapted for joining laser housing portions, which insulator comprises: an annulus; a channel in the annulus traversing the circumference and length of the housing; at least two ports, each communicating with the channel and an outer surface of the housing; and an attachment for securely attaching each end of the annulus to a laser housing member.

Core disruptive accident margin seal

DOEpatents

Golden, Martin P.

1979-01-01

Apparatus for sealing the annulus defined within a substantially cylindrical rotatable riser assembly and plug combination of a nuclear reactor closure head. The apparatus comprises an inflatable sealing mechanism disposed in one portion of the riser assembly near the annulus such that upon inflation the sealing mechanism is radially actuated against the other portion of the riser assembly thereby sealing the annulus. The apparatus further comprises a connecting mechanism which places one end of the sealing mechanism in fluid communication with the reactor cover gas so that overpressurization of the reactor cover gas will increase the radial actuation of the sealing mechanism thus enhancing sealing of the annulus.

The shape and motion of gas bubbles in a liquid flowing through a thin annulus

NASA Astrophysics Data System (ADS)

Lei, Qinghua; Xie, Zhihua; Pavlidis, Dimitrios; Salinas, Pablo; Veltin, Jeremy; Muggeridge, Ann; Pain, Christopher C.; Matar, Omar K.; Jackson, Matthew; Arland, Kristine; Gyllensten, Atle

2017-11-01

We study the shape and motion of gas bubbles in a liquid flowing through a horizontal or slightly-inclined thin annulus. Experimental data show that in the horizontal annulus, bubbles develop a unique ``tadpole'' shape with an elliptical cap and a highly-stretched tail, due to the confinement between the closely-spaced channel walls. As the annulus is inclined, the bubble tail tends to decrease in length, while the geometry of the cap remains almost invariant. To model the bubble evolution, the thin annulus is conceptualised as a ``Hele-Shaw'' cell in a curvilinear space. The three-dimensional flow within the cell is represented by a gap-averaged, two-dimensional model constrained by the same dimensionless quantities. The complex bubble dynamics are solved using a mixed control-volume finite-element method combined with interface-capturing and mesh adaptation techniques. A close match to the experimental data is achieved, both qualitatively and quantitatively, by the numerical simulations. The mechanism for the elliptical cap formation is interpreted based on an analogous irrotational flow field around a circular cylinder. The shape regimes of bubbles flowing through the thin annulus are further explored based on the simulation results. Funding from STATOIL gratefully acknowledged.

Numerical simulation of volume-controlled mechanical ventilated respiratory system with 2 different lungs.

PubMed

Shi, Yan; Zhang, Bolun; Cai, Maolin; Zhang, Xiaohua Douglas

2017-09-01

Mechanical ventilation is a key therapy for patients who cannot breathe adequately by themselves, and dynamics of mechanical ventilation system is of great significance for life support of patients. Recently, models of mechanical ventilated respiratory system with 1 lung are used to simulate the respiratory system of patients. However, humans have 2 lungs. When the respiratory characteristics of 2 lungs are different, a single-lung model cannot reflect real respiratory system. In this paper, to illustrate dynamic characteristics of mechanical ventilated respiratory system with 2 different lungs, we propose a mathematical model of mechanical ventilated respiratory system with 2 different lungs and conduct experiments to verify the model. Furthermore, we study the dynamics of mechanical ventilated respiratory system with 2 different lungs. This research study can be used for improving the efficiency and safety of volume-controlled mechanical ventilation system. Copyright © 2016 John Wiley & Sons, Ltd.

Simultaneous effects of single wall carbon nanotube and effective variable viscosity for peristaltic flow through annulus having permeable walls

NASA Astrophysics Data System (ADS)

Shahzadi, Iqra; Nadeem, S.; Rabiei, Faranak

The current article deals with the combine effects of single wall carbon nanotubes and effective viscosity for the peristaltic flow of nanofluid through annulus. The nature of the walls is assumed to be permeable. The present theoretical model can be considered as mathematical representation to the motion of conductive physiological fluids in the existence of the endoscope tube which has many biomedical applications such as drug delivery system. The outer tube has a wave of sinusoidal nature that is travelling along its walls while the inner tube is rigid and uniform. Lubrication approach is used for the considered analysis. An empirical relation for the effective variable viscosity of nanofluid is proposed here interestingly. The viscosity of nanofluid is the function of radial distance and the concentration of nanoparticles. Exact solution for the resulting system of equations is displayed for various quantities of interest. The outcomes show that the maximum velocity of SWCNT-blood nanofluid enhances for larger values of viscosity parameter. The pressure gradient in the more extensive part of the annulus is likewise found to increase as a function of variable viscosity parameter. The size of the trapped bolus is also influenced by variable viscosity parameter. The present examination also revealed that the carbon nanotubes have many applications related to biomedicine.

Histological observation of a gelatin sponge transplant loaded with bone marrow-derived mesenchymal stem cells combined with platelet-rich plasma in repairing an annulus defect

PubMed Central

Xu, Xiang; Hu, Jianzhong; Lu, Hongbin

2017-01-01

Objective To research the histological characteristics of a gelatin sponge transplant loaded with goat BMSCs (bone marrow-derived mesenchymal stem cells) combined with PRP (platelet-rich plasma) in repairing an annulus defect. Method BMSCs were separated from the iliac crest of goats, sub-cultured and identified after the third generation. Then, PRP was obtained using blood from the jugular vein of goats via two degrees of centrifugation. In the animal experiments, the goats were divided into the following three groups: a sham group, an injury group and a therapeutic group. In the sham group, we decompressed the lamina and exposed the annulus fibrosus. In the injury group, we exposed the annulus fibrosus after decompression of the lamina and created a 1 × 1 cm defect in the annulus using surgical instruments. In the therapeutic group, after decompression of the lamina, we exposed the annulus, created a 1 × 1 cm defect using surgical instruments, and placed a gelatin sponge combined with BMSCs and PRP into the defect for a combined method of repair. Three, six and twelve weeks after the surgery, the previously damaged or undamaged annulus tissue was removed from the three groups. Then, the above tissue was assayed using HE (hematoxylin-eosin) staining, Masson trichrome staining, AB-PAS (Alcian blue-periodic acid Schiff) staining, and type II collagen staining and observed by microscopy. Results From the HE staining, we observed that the number of repair cells gradually increased. Compared to the injury group, the cell density and gross morphology of cells in the therapeutic group were closer to those of the sham group. As observed by Masson trichrome gelatin staining, many of the fibroblast cells or tissues were under repair, and as time progressed, the number of fibroblast cells and amount of tissue gradually increased. The results of the AB-PAS staining suggest that chondrocytes participated in the repair of the annulus. The level of type II collagen gradually increased, as determined by immunohistochemical staining. Conclusion Our results demonstrate that a gelatin sponge transplant loaded with BMSCs and PRP can effectively repair annulus defects. PMID:28178294

Limit Cycle Bifurcations Near a Piecewise Smooth Generalized Homoclinic Loop with a Saddle-Fold Point

NASA Astrophysics Data System (ADS)

Liang, Feng; Wang, Dechang

In this paper, we suppose that a planar piecewise Hamiltonian system, with a straight line of separation, has a piecewise generalized homoclinic loop passing through a Saddle-Fold point, and assume that there exists a family of piecewise smooth periodic orbits near the loop. By studying the asymptotic expansion of the first order Melnikov function corresponding to the period annulus, we obtain the formulas of the first six coefficients in the expansion, based on which, we provide a lower bound for the maximal number of limit cycles bifurcated from the period annulus. As applications, two concrete systems are considered. Especially, the first one reveals that a quadratic piecewise Hamiltonian system can have five limit cycles near a generalized homoclinic loop under a quadratic piecewise smooth perturbation. Compared with the smooth case [Horozov & Iliev, 1994; Han et al., 1999], three more limit cycles are found.

Feedwater temperature control methods and systems

DOEpatents

Moen, Stephan Craig; Noonan, Jack Patrick; Saha, Pradip

2014-04-22

A system for controlling the power level of a natural circulation boiling water nuclear reactor (NCBWR) is disclosed. The system, in accordance with an example embodiment of the present invention, may include a controller configured to control a power output level of the NCBWR by controlling a heating subsystem to adjust a temperature of feedwater flowing into an annulus of the NCBWR. The heating subsystem may include a steam diversion line configured to receive steam generated by a core of the NCBWR and a steam bypass valve configured to receive commands from the controller to control a flow of the steam in the steam diversion line, wherein the steam received by the steam diversion line has not passed through a turbine. Additional embodiments of the invention may include a feedwater bypass valve for controlling an amount of flow of the feedwater through a heater bypass line to the annulus.

SY Tank Farm ventilation isolation option risk assessment report

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

Powers, T.B.; Morales, S.D.

The safety of the 241-SY Tank Farm ventilation system has been under extensive scrutiny due to safety concerns associated with tank 101-SY. Hydrogen and other gases are generated and trapped in the waste below the liquid surface. Periodically, these gases are released into the dome space and vented through the exhaust system. This attention to the ventilation system has resulted in the development of several alternative ventilation system designs. The ventilation system provides the primary means of mitigation of accidents associated with flammable gases. This report provides an assessment of various alternatives ventilation system designs.

Technology Solutions Case Study: Ventilation System Effectiveness and Tested Indoor Air Quality Impacts

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

A. Rudd and D. Bergey

Ventilation system effectiveness testing was conducted at two unoccupied, single-family, detached lab homes at the University of Texas - Tyler. Five ventilation system tests were conducted with various whole-building ventilation systems. Multizone fan pressurization testing characterized building and zone enclosure leakage. PFT testing showed multizone air change rates and interzonal airflow filtration. Indoor air recirculation by a central air distribution system can help improve the exhaust ventilation system by way of air mixing and filtration. In contrast, the supply and balanced ventilation systems showed that there is a significant benefit to drawing outside air from a known outside location, andmore » filtering and distributing that air. Compared to the Exhaust systems, the CFIS and ERV systems showed better ventilation air distribution and lower concentrations of particulates, formaldehyde and other VOCs.« less

Building America Case Study: Ventilation System Effectiveness and Tested Indoor Air Quality Impacts, Tyler, Texas

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

?Ventilation system effectiveness testing was conducted at two unoccupied, single-family, detached lab homes at the University of Texas - Tyler. Five ventilation system tests were conducted with various whole-building ventilation systems. Multizone fan pressurization testing characterized building and zone enclosure leakage. PFT testing showed multizone air change rates and interzonal airflow filtration. Indoor air recirculation by a central air distribution system can help improve the exhaust ventilation system by way of air mixing and filtration. In contrast, the supply and balanced ventilation systems showed that there is a significant benefit to drawing outside air from a known outside location, andmore » filtering and distributing that air. Compared to the Exhaust systems, the CFIS and ERV systems showed better ventilation air distribution and lower concentrations of particulates, formaldehyde and other VOCs. System improvement percentages were estimated based on four System Factor Categories: Balance, Distribution, Outside Air Source, and Recirculation Filtration. Recommended System Factors could be applied to reduce ventilation fan airflow rates relative to ASHRAE Standard 62.2 to save energy and reduce moisture control risk in humid climates. HVAC energy savings were predicted to be 8-10%, or $50-$75/year. Cumulative particle counts for six particle sizes, and formaldehyde and other Top 20 VOC concentrations were measured in multiple zones. The testing showed that single-point exhaust ventilation was inferior as a whole-house ventilation strategy.« less

Mobile communication devices causing interference in invasive and noninvasive ventilators.

PubMed

Dang, Bao P; Nel, Pierre R; Gjevre, John A

2007-06-01

The aim of this study was to assess if common mobile communication systems would cause significant interference on mechanical ventilation devices and at what distances would such interference occur. We tested all the invasive and noninvasive ventilatory devices used within our region. This consisted of 2 adult mechanical ventilators, 1 portable ventilator, 2 pediatric ventilators, and 2 noninvasive positive pressure ventilatory devices. We operated the mobile devices from the 2 cellular communication systems (digital) and 1 2-way radio system used in our province at varying distances from the ventilators and looked at any interference they created. We tested the 2-way radio system, which had a fixed operation power output of 3.0 watts, the Global Systems for Mobile Communication cellular system, which had a maximum power output of 2.0 watts and the Time Division Multiple Access cellular system, which had a maximum power output of 0.2 watts on our ventilators. The ventilators were ventilating a plastic lung at fixed settings. The mobile communication devices were tested at varying distances starting at zero meter from the ventilator and in all operation modes. The 2-way radio caused the most interference on some of the ventilators, but the maximum distance of interference was 1.0 m. The Global Systems for Mobile Communication system caused significant interference only at 0 m and minor interference at 0.5 m on only 1 ventilator. The Time Division Multiple Access system caused no interference at all. Significant interference consisted of a dramatic rise and fluctuation of the respiratory rate, pressure, and positive end-expiratory pressure of the ventilators with no normalization when the mobile device was removed. From our experiment on our ventilators with the communication systems used in our province, we conclude that mobile communication devices such as cellular phones and 2-way radios are safe and cause no interference unless operated at very close distances of less than 1 meter.

The chemokine, CXCL16, and its receptor, CXCR6, are constitutively expressed in human annulus fibrosus and expression of CXCL16 is up-regulated by exposure to IL-1ß in vitro.

PubMed

Gruber, H E; Marrero, E; Ingram, J A; Hoelscher, G L; Hanley, E N

2017-01-01

Chemokines are an important group of soluble molecules with specialized functions in inflammation. The roles of many specialized chemokines and their receptors remain poorly understood in the human intervertebral disc. We investigated CXCL16 and its receptor, CXCR6, to determine their immunolocalization in disc tissue and their presence following exposure of cultured human annulus fibrosus cells to proinflammatory cytokines. CXCL16 is a marker for inflammation; it also can induce hypoxia-inducible factor 1α (HIF-1α), which is a phenotypic marker of heathy nucleus pulposus tissue. We found CXCL16 and CXCR6 immunostaining in many cells of the annulus portion of the disc. Molecular studies showed that annulus fibrosus cells exposed to IL-1ß, but not TNF-α, exhibited significant up-regulation of CXCL16 expression vs. control cells. There was no significant difference in the percentage of annulus cells that exhibited immunolocalization of CXCL16 in grade I/II, grade III or grade IV/V specimens. The presence of CXCL16 and its receptor, CXCR6, in the annulus in vivo suggests the need for future research concerning the role of this chemokine in proinflammatory functions, HIF-1α expression and disc vascularization.

Analysis of radon reduction and ventilation systems in uranium mines in China.

PubMed

Hu, Peng-hua; Li, Xian-jie

2012-09-01

Mine ventilation is the most important way of reducing radon in uranium mines. At present, the radon and radon progeny levels in Chinese uranium mines where the cut and fill stoping method is used are 3-5 times higher than those in foreign uranium mines, as there is not much difference in the investments for ventilation protection between Chinese uranium mines and international advanced uranium mines with compaction methodology. In this paper, through the analysis of radon reduction and ventilation systems in Chinese uranium mines and the comparison of advantages and disadvantages between a variety of ventilation systems in terms of radon control, the authors try to illustrate the reasons for the higher radon and radon progeny levels in Chinese uranium mines and put forward some problems in three areas, namely the theory of radon control and ventilation systems, radon reduction ventilation measures and ventilation management. For these problems, this paper puts forward some proposals regarding some aspects, such as strengthening scrutiny, verifying and monitoring the practical situation, making clear ventilation plans, strictly following the mining sequence, promoting training of ventilation staff, enhancing ventilation system management, developing radon reduction ventilation technology, purchasing ventilation equipment as soon as possible in the future, and so on.

Creeping gaseous flows through elastic tube and annulus micro-configurations

NASA Astrophysics Data System (ADS)

Elbaz, Shai; Jacob, Hila; Gat, Amir

2016-11-01

Gaseous flows in elastic micro-configurations is relevant to biological systems (e.g. alveolar ducts in the lungs) as well as to applications such as gas actuated soft micro-robots. We here examine the effect of low-Mach-number compressibility on creeping gaseous axial flows through linearly elastic tube and annulus micro-configurations. For steady flows, the leading-order effects of elasticity on the pressure distribution and mass-flux are obtained. For transient flow in a tube with small deformations, elastic effects are shown to be negligible in leading order due to compressibility. We then examine transient flows in annular configurations where the deformation is significant compared with the gap between the inner and outer cylinders defining the annulus. Both compressibility and elasticity are obtained as dominant terms interacting with viscosity. For a sudden flux impulse, the governing non-linear leading order diffusion equation is initially approximated by a porous-medium-equation of order 2.5 for the pressure square. However, as the fluid expand and the pressure decreases, the governing equation degenerates to a porous-medium-equation of order 2 for the pressure.

Speckle tracking evaluation of right ventricular functions in children with sickle cell disease.

PubMed

Tolba, Osama Abd Rab Elrasol; El-Shanshory, Mohamed Ramadan; El-Gamasy, Mohamed Abd Elaziz; El-Shehaby, Walid Ahmed

2017-01-01

Cardiac dysfunction is a risk factor for death in patients with sickle cell disease (SCD). Aim of the work is to evaluate the right ventricular systolic and diastolic functions by tissue Doppler and speckling tracking imaging in children with SCD. Thirty children with SCD and thirty controls were subjected to clinical, laboratory evaluations, and echocardiographic study using GE Vivid 7 (GE Medical System, Horten, Norway with a 3.5-MHz multifrequency transducer) including; Two-dimensional and tissue Doppler echocardiographic study (lateral tricuspid valve annulus peak E' velocity, lateral tricuspid valve annulus peak A' velocity, E'/A' ratio, isovolumetric relaxation time, lateral tricuspid valve annulus S' and septal S' waves and peak longitudinal systolic strain [PLSS] and time to PLSS) were done in six right ventricular segments. There was a significant decrease in right ventricular systolic and diastolic function in patients group when compared to controls. Children with SCD have impaired right ventricular systolic and diastolic functions when compared to healthy children with early evaluation of the systolic dysfunction by speckle tracking imaging technique.

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

PubMed Central

Shi, Yan; Ren, Shuai; Cai, Maolin; Xu, Weiqing; Deng, Qiyou

2014-01-01

Mechanical ventilation is an important life support treatment of critically ill patients, and air pressure dynamics of human lung affect ventilation treatment effects. In this paper, in order to obtain the influences of seven key parameters of mechanical ventilation system on the pressure dynamics of human lung, firstly, mechanical ventilation system was considered as a pure pneumatic system, and then its mathematical model was set up. Furthermore, to verify the mathematical model, a prototype mechanical ventilation system of a lung simulator was proposed for experimental study. Last, simulation and experimental studies on the air flow dynamic of the mechanical ventilation system were done, and then the pressure dynamic characteristics of the mechanical system were obtained. The study can be referred to in the pulmonary diagnostics, treatment, and design of various medical devices or diagnostic systems. PMID:25197318

Observations of the north polar water ice annulus on Mars using THEMIS and TES

USGS Publications Warehouse

Wagstaff, K.L.; Titus, T.N.; Ivanov, A.B.; Castano, R.; Bandfield, J.L.

2008-01-01

The Martian seasonal CO2 ice caps advance and retreat each year. In the spring, as the CO2 cap gradually retreats, it leaves behind an extensive defrosting zone from the solid CO2 cap to the location where all CO2 frost has sublimated. We have been studying this phenomenon in the north polar region using data from the THermal EMission Imaging System (THEMIS), a visible and infra-red (IR) camera on the Mars Odyssey spacecraft, and the Thermal Emission Spectrometer (TES) on Mars Global Surveyor. Recently, we discovered that some THEMIS images of the CO2 defrosting zone contain evidence for a distinct defrosting phenomenon: some areas just south of the CO2 cap edge are too bright in visible wavelengths to be defrosted terrain, but too warm in the IR to be CO2 ice. We hypothesize that we are seeing evidence for a seasonal annulus of water ice (frost) that recedes with the seasonal CO2 cap, as predicted by previous workers. In this paper, we describe our observations with THEMIS and compare them to simultaneous observations by TES and OMEGA. All three instruments find that this phenomenon is distinct from the CO2 cap and most likely composed of water ice. We also find strong evidence that the annulus widens as it recedes. Finally, we show that this annulus can be detected in the raw THEMIS data as it is collected, enabling future long-term onboard monitoring. ?? 2007.

Ventilation System Effectiveness and Tested Indoor Air Quality Impacts

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

Rudd, Armin; Bergey, Daniel

In this project, Building America research team Building Science Corporation tested the effectiveness of ventilation systems at two unoccupied, single-family, detached lab homes at the University of Texas - Tyler. Five ventilation system tests were conducted with various whole-building ventilation systems. Multizone fan pressurization testing characterized building and zone enclosure leakage. PFT testing showed multizone air change rates and interzonal airflow. Cumulative particle counts for six particle sizes, and formaldehyde and other Top 20 VOC concentrations were measured in multiple zones. The testing showed that single-point exhaust ventilation was inferior as a whole-house ventilation strategy. This was because the sourcemore » of outside air was not direct from outside, the ventilation air was not distributed, and no provision existed for air filtration. Indoor air recirculation by a central air distribution system can help improve the exhaust ventilation system by way of air mixing and filtration. In contrast, the supply and balanced ventilation systems showed that there is a significant benefit to drawing outside air from a known outside location, and filtering and distributing that air. Compared to the exhaust systems, the CFIS and ERV systems showed better ventilation air distribution and lower concentrations of particulates, formaldehyde and other VOCs. System improvement percentages were estimated based on four system factor categories: balance, distribution, outside air source, and recirculation filtration. Recommended system factors could be applied to reduce ventilation fan airflow rates relative to ASHRAE Standard 62.2 to save energy and reduce moisture control risk in humid climates. HVAC energy savings were predicted to be 8-10%, or $50-$75/year.« less

Ventilation System Effectiveness and Tested Indoor Air Quality Impacts

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

Rudd, Armin; Bergey, Daniel

Ventilation system effectiveness testing was conducted at two unoccupied, single-family, detached lab homes at the University of Texas - Tyler. Five ventilation system tests were conducted with various whole-building ventilation systems. Multizone fan pressurization testing characterized building and zone enclosure leakage. PFT testing showed multizone air change rates and interzonal airflow. Cumulative particle counts for six particle sizes, and formaldehyde and other Top 20 VOC concentrations were measured in multiple zones. The testing showed that single-point exhaust ventilation was inferior as a whole-house ventilation strategy. It was inferior because the source of outside air was not direct from outside, themore » ventilation air was not distributed, and no provision existed for air filtration. Indoor air recirculation by a central air distribution system can help improve the exhaust ventilation system by way of air mixing and filtration. In contrast, the supply and balanced ventilation systems showed that there is a significant benefit to drawing outside air from a known outside location, and filtering and distributing that air. Compared to the Exhaust systems, the CFIS and ERV systems showed better ventilation air distribution and lower concentrations of particulates, formaldehyde and other VOCs. System improvement percentages were estimated based on four System Factor Categories: Balance, Distribution, Outside Air Source, and Recirculation Filtration. Recommended System Factors could be applied to reduce ventilation fan airflow rates relative to ASHRAE Standard 62.2 to save energy and reduce moisture control risk in humid climates. HVAC energy savings were predicted to be 8-10%, or $50-$75/year.« less

Analysis of the systems of ventilation of residential houses of Ukraine and Estonia

NASA Astrophysics Data System (ADS)

Savchenko, Olena; Zhelykh, Vasyl; Voll, Hendrik

2017-12-01

The most common ventilation system in residential buildings in Ukraine is natural ventilation. In recent years, due to increased tightness of structures, an increase in the content of synthetic finishing materials in them, the quality of microclimate parameters deteriorated. One of the measures to improve the parameters of indoor air in residential buildings is the use of mechanical inflow and exhaust ventilation system. In this article the regulatory documents concerning the design of ventilation systems in Ukraine and Estonia and the requirements for air exchange in residential buildings are considered. It is established that the existing normative documents in Ukraine are analogous to European norms, which allow design the system of ventilation of residential buildings according to European standards. However, the basis for the design of ventilation systems in Ukraine is the national standards, in which mechanical ventilation, unfortunately, is provided only for the design of high-rise buildings. To maintain acceptable microclimate parameters in residential buildings, it is advisable for designers to apply the requirements for designing ventilation systems in accordance with European standards.

Correlates of tricuspid regurgitation as determined by 3D echocardiography: pulmonary arterial pressure, ventricle geometry, annular dilatation, and papillary muscle displacement.

PubMed

Spinner, Erin M; Lerakis, Stamatios; Higginson, Jason; Pernetz, Maria; Howell, Sharon; Veledar, Emir; Yoganathan, Ajit P

2012-01-01

While it is understood that annular dilatation contributes to tricuspid regurgitation (TR), other factors are less clear. The geometry of the right ventricle (RV) and left ventricle (LV) may alter tricuspid annulus size and papillary muscle (PM) positions leading to TR. Three-dimensional echocardiographic images were obtained at Emory University Hospital using a GE Vivid 7 ultrasound system. End-diastolic area was used to classify ventricle geometry: control (n=21), isolated RV dilatation (n=17), isolated LV dilatation (n=13), and both RV and LV dilatation (n=13). GE EchoPAC was used to measure annulus area and position of the PM tips. Patients with RV dilatation had significant (P≤ 0.05) displacement of all PMs apically and the septal PM and posterior PM away from the center of the RV toward the LV. Patients with LV dilatation had significant (P≤0.05) apical displacement of the anterior PM. Pulmonary arterial pressure (r=0.66), annulus area (r=0.51), apical displacement of the anterior PM (r=0.26), posterior PM (r=0.49), and septal PM (r=0.40), lateral displacement of the septal PM (r=0.37) and posterior PM (r=0.40), and tenting area and height (r=0.54, 0.49), were significantly (P≤0.05) correlated to the grade of TR. Ventricle classification (r=0.46) and RV end-diastolic area (r=0.48) also were correlated with the grade of TR. A regression analysis found ventricle classification (P=0.001), pulmonary arterial pressure (P≤0.001) annulus area (P=0.027), and apical displacement of the anterior PM (P=0.061) to be associated with the grade of TR. Alterations in ventricular geometry can lead to TR by altering both tricuspid annulus size and PM position. Understanding these geometric interactions with the aim of correcting pathological alterations of the tricuspid valve apparatus may lead to more robust repairs.

Occupational exposure to nitrous oxide - the role of scavenging and ventilation systems in reducing the exposure level in operating rooms.

PubMed

Krajewski, Wojciech; Kucharska, Malgorzata; Wesolowski, Wiktor; Stetkiewicz, Jan; Wronska-Nofer, Teresa

2007-03-01

The aim of this study was to assess the level of occupational exposure to nitrous oxide (N(2)O) in operating rooms (ORs), as related to different ventilation and scavenging systems used to remove waste anaesthetic gases from the work environment. The monitoring of N(2)O in the air covered 35 ORs in 10 hospitals equipped with different systems for ventilation and anaesthetic scavenging. The examined systems included: natural ventilation with supplementary fresh air provided by a pressure ventilation system (up to 6 air changes/h); pressure and exhaust ventilation systems equipped with ventilation units supplying fresh air to and discharging contaminated air outside the working area (more than 10 air changes/h); complete air-conditioning system with laminar air flow (more than 15 air changes/h). The measurements were carried out during surgical procedures (general anaesthesia induced intravenously and maintained with inhaled N(2)O and sevofluran delivered through cuffed endotracheal tubes) with connected or disconnected air scavenging. Air was collected from the breathing zone of operating personnel continuously through the whole time of anaesthesia to Tedlar((R)) bags, and N(2)O concentrations in air samples were analyzed by adsorption gas chromatography/mass spectrometry. N(2)O levels in excess of the occupational exposure limit (OEL) value of 180mg/m(3) were registered in all ORs equipped with ventilation systems alone. The OEL value was exceeded several times in rooms with natural ventilation plus supplementary pressure ventilations and twice or less in those with pressure/exhaust ventilation systems or air conditioning. N(2)O levels below or within the OEL value were observed in rooms where the system of air conditioning or pressure/exhaust ventilation was combined with scavenging systems. Systems combining natural/pressure ventilation with scavenging were inadequate to maintain N(2)O concentration below the OEL value. Air conditioning and an efficient pressure/exhaust ventilation (above 12 air exchanges/h) together with efficient active scavenging systems are sufficient to sustain N(2)O exposure in ORs at levels below or within the OEL value of 180mg/m(3).

Nuclear reactor target assemblies, nuclear reactor configurations, and methods for producing isotopes, modifying materials within target material, and/or characterizing material within a target material

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

Toth, James J.; Wall, Donald; Wittman, Richard S.

Target assemblies are provided that can include a uranium-comprising annulus. The assemblies can include target material consisting essentially of non-uranium material within the volume of the annulus. Reactors are disclosed that can include one or more discrete zones configured to receive target material. At least one uranium-comprising annulus can be within one or more of the zones. Methods for producing isotopes within target material are also disclosed, with the methods including providing neutrons to target material within a uranium-comprising annulus. Methods for modifying materials within target material are disclosed as well as are methods for characterizing material within a targetmore » material.« less

An experimental system for coiled tubing partial underbalanced drilling (CT-PUBD) technique

NASA Astrophysics Data System (ADS)

Shi, H. Z.; Ji, Z. S.; Zhao, H. Q.; Chen, Z. L.; Zhang, H. Z.

2018-05-01

To improve the rate of penetration (ROP) in hard formations, a new high-speed drilling technique called Coiled Tubing Partial Underbalanced Drilling (CT-PUBD) is proposed. This method uses a rotary packer to realize an underbalanced condition near the bit by creating a micro-annulus and an overbalanced condition at the main part of the annulus. A new full-scale laboratory experimental system is designed and set up to study the hydraulic characteristics and drilling performance of this method. The system is composed of a drilling system, circulation system, and monitor system, including three key devices, namely, cuttings discharge device, rotary packer, and backflow device. The experimental results showed that the pressure loss increased linearly with the flow rate of the drilling fluid. The high drilling speed of CT-PUBD proved it a better drilling method than the conventional drilling. The experimental system may provide a fundamental basis for the research of CT-PUBD, and the results proved that this new method is feasible in enhancing ROP and guaranteeing the drilling safety.

46 CFR 153.312 - Ventilation system standards.

Code of Federal Regulations, 2013 CFR

2013-10-01

... CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Design and Equipment Cargo Handling Space Ventilation § 153.312 Ventilation system standards. A cargo handling space ventilation... (approx. 32.8 ft) from openings into or ventilation intakes for, accommodation or service spaces. (b) A...

46 CFR 153.312 - Ventilation system standards.

Code of Federal Regulations, 2012 CFR

2012-10-01

... CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Design and Equipment Cargo Handling Space Ventilation § 153.312 Ventilation system standards. A cargo handling space ventilation... (approx. 32.8 ft) from openings into or ventilation intakes for, accommodation or service spaces. (b) A...

46 CFR 153.312 - Ventilation system standards.

Code of Federal Regulations, 2011 CFR

2011-10-01

... CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Design and Equipment Cargo Handling Space Ventilation § 153.312 Ventilation system standards. A cargo handling space ventilation... (approx. 32.8 ft) from openings into or ventilation intakes for, accommodation or service spaces. (b) A...

46 CFR 153.312 - Ventilation system standards.

Code of Federal Regulations, 2014 CFR

2014-10-01

... CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Design and Equipment Cargo Handling Space Ventilation § 153.312 Ventilation system standards. A cargo handling space ventilation... (approx. 32.8 ft) from openings into or ventilation intakes for, accommodation or service spaces. (b) A...

46 CFR 153.312 - Ventilation system standards.

Code of Federal Regulations, 2010 CFR

2010-10-01

... CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Design and Equipment Cargo Handling Space Ventilation § 153.312 Ventilation system standards. A cargo handling space ventilation... (approx. 32.8 ft) from openings into or ventilation intakes for, accommodation or service spaces. (b) A...

Successful ablation of a right atrium-axillary ventricular accessory pathway associated with Wolff-Parkinson-White syndrome.

PubMed

Yuan, Yuan; Long, Deyong; Dong, Jianzeng; Tao, Ling; Ma, Changsheng

2017-12-01

We report a case of a patient with right axillary ventricular. Similar congenital anomaly of the right atrium was reported as "right appendage diverticulum or right atrial diverticulum." However, this independent chamber has its own annulus, synchronizes with the right ventricular, and generates large ventricular potential. Under the guidance of the CARTO mapping system (Biosense Webster, Diamond Bar, CA, USA), a right atrioventricular accessory pathway associated with type B Wolff-Parkinson-White syndrome was ablated successfully. This pathway was close to the annulus of the axillary ventricular. The patient remained free of arrhythmia at 1-year follow-up. © 2017 Wiley Periodicals, Inc.

Using a Ventilation Controller to Optimize Residential Passive Ventilation For Energy and Indoor Air Quality

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

Turner, William; Walker, Iain

One way to reduce the energy impact of providing residential ventilation is to use passive and hybrid systems. However, these passive and hybrid (sometimes called mixed-mode) systems must still meet chronic and acute health standards for ventilation. This study uses a computer simulation approach to examine the energy and indoor air quality (IAQ) implications of passive and hybrid ventilation systems, in 16 California climate zones. Both uncontrolled and flow controlled passive stacks are assessed. A new hybrid ventilation system is outlined that uses an intelligent ventilation controller to minimise energy use, while ensuring chronic and acute IAQ standards are met.more » ASHRAE Standard 62.2-2010 – the United States standard for residential ventilation - is used as the chronic standard, and exposure limits for PM 2.5, formaldehyde and NO 2 are used as the acute standards.The results show that controlled passive ventilation and hybrid ventilation can be used in homes to provide equivalent IAQ to continuous mechanical ventilation, for less use of energy.« less

Influence of the Quantity of Aortic Valve Calcium on the Agreement Between Automated 3-Dimensional Transesophageal Echocardiography and Multidetector Row Computed Tomography for Aortic Annulus Sizing.

PubMed

Podlesnikar, Tomaz; Prihadi, Edgard A; van Rosendael, Philippe J; Vollema, E Mara; van der Kley, Frank; de Weger, Arend; Ajmone Marsan, Nina; Naji, Franjo; Fras, Zlatko; Bax, Jeroen J; Delgado, Victoria

2018-01-01

Accurate aortic annulus sizing is key for selection of appropriate transcatheter aortic valve implantation (TAVI) prosthesis size. The present study compared novel automated 3-dimensional (3D) transesophageal echocardiography (TEE) software and multidetector row computed tomography (MDCT) for aortic annulus sizing and investigated the influence of the quantity of aortic valve calcium (AVC) on the selection of TAVI prosthesis size. A total of 83 patients with severe aortic stenosis undergoing TAVI were evaluated. Maximal and minimal aortic annulus diameter, perimeter, and area were measured. AVC was assessed with computed tomography. The low and high AVC burden groups were defined according to the median AVC score. Overall, 3D TEE measurements slightly underestimated the aortic annulus dimensions as compared with MDCT (mean differences between maximum, minimum diameter, perimeter, and area: -1.7 mm, 0.5 mm, -2.7 mm, and -13 mm 2 , respectively). The agreement between 3D TEE and MDCT on aortic annulus dimensions was superior among patients with low AVC burden (<3,025 arbitrary units) compared with patients with high AVC burden (≥3,025 arbitrary units). The interobserver variability was excellent for both methods. 3D TEE and MDCT led to the same prosthesis size selection in 88%, 95%, and 81% of patients in the total population, the low, and the high AVC burden group, respectively. In conclusion, the novel automated 3D TEE imaging software allows accurate and highly reproducible measurements of the aortic annulus dimensions and shows excellent agreement with MDCT to determine the TAVI prosthesis size, particularly in patients with low AVC burden. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

Cyanoacrylate medical glue application in intervertebral disc annulus defect repair: Mechanical and biocompatible evaluation.

PubMed

Kang, Ran; Li, Haisheng; Lysdahl, Helle; Quang Svend Le, Dang; Chen, Menglin; Xie, Lin; Bünger, Cody

2017-01-01

In an attempt to find an ideal closure method during annulus defect repair, we evaluate the use of medical glue by mechanical and biocompatible test. Cyanoacrylate medical glue was applied together with a multilayer microfiber/nanofiber polycaprolactone scaffold and suture in annulus repair. Continuous axial loading and fatigue mechanical test was performed. Furthermore, the in vitro response of mesenchymal stem cell (MSC) to the glue was evaluated by cell viability assay. The in vivo response of annulus tissue to the glue and scaffold was also studied in porcine lumbar spine; histological sections were evaluated after 3 months. Cyanoacrylate glue significantly improved the closure effect in the experimental group with failure load 2825.7 ± 941.6 N, compared to 774.1 ± 281.3 N in the control group without glue application (p < 0.01). The experimental group also withstood the fatigue test. No toxic effect was observed by in vitro cell culture and in vivo implantation. On the basis of this initial evaluation, the use of cyanoacrylate medical glue improves closure effect with no toxicity in annulus defect repair. This method of annulus repair merits further effectiveness study in vivo. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 14-20, 2017. © 2015 Wiley Periodicals, Inc.

76 FR 36548 - Circulatory System Devices Panel of the Medical Devices Advisory Committee; Notice of Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2011-06-22

...] Circulatory System Devices Panel of the Medical Devices Advisory Committee; Notice of Meeting AGENCY: Food and... of Committee: Circulatory System Devices Panel of the Medical Devices Advisory Committee. General... also comes with a sheath, introducer, loader, dilator, balloon (used to pre-dilate the native annulus...

77 FR 25183 - Circulatory System Devices Panel of the Medical Devices Advisory Committee; Notice of Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2012-04-27

...] Circulatory System Devices Panel of the Medical Devices Advisory Committee; Notice of Meeting AGENCY: Food and... of Committee: Circulatory System Devices Panel of the Medical Devices Advisory Committee. General..., introducer, loader, dilator, balloon (used to pre-dilate the native annulus) and a crimper. FDA intends to...

Variable flow control for a nuclear reactor control rod

DOEpatents

Carleton, Richard D.; Bhattacharyya, Ajay

1978-01-01

A variable flow control for a control rod assembly of a nuclear reactor that depends on turbulent friction though an annulus. The annulus is formed by a piston attached to the control rod drive shaft and a housing or sleeve fitted to the enclosure housing the control rod. As the nuclear fuel is burned up and the need exists for increased reactivity, the control rods are withdrawn, which increases the length of the annulus and decreases the rate of coolant flow through the control rod assembly.

46 CFR 111.103-3 - Machinery space ventilation.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 4 2013-10-01 2013-10-01 false Machinery space ventilation. 111.103-3 Section 111.103-3...-GENERAL REQUIREMENTS Remote Stopping Systems § 111.103-3 Machinery space ventilation. (a) Each machinery space ventilation system must have two controls to stop the ventilation, one of which may be the supply...

46 CFR 111.103-3 - Machinery space ventilation.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 4 2011-10-01 2011-10-01 false Machinery space ventilation. 111.103-3 Section 111.103-3...-GENERAL REQUIREMENTS Remote Stopping Systems § 111.103-3 Machinery space ventilation. (a) Each machinery space ventilation system must have two controls to stop the ventilation, one of which may be the supply...

46 CFR 111.103-3 - Machinery space ventilation.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 4 2012-10-01 2012-10-01 false Machinery space ventilation. 111.103-3 Section 111.103-3...-GENERAL REQUIREMENTS Remote Stopping Systems § 111.103-3 Machinery space ventilation. (a) Each machinery space ventilation system must have two controls to stop the ventilation, one of which may be the supply...

46 CFR 111.103-3 - Machinery space ventilation.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 4 2014-10-01 2014-10-01 false Machinery space ventilation. 111.103-3 Section 111.103-3...-GENERAL REQUIREMENTS Remote Stopping Systems § 111.103-3 Machinery space ventilation. (a) Each machinery space ventilation system must have two controls to stop the ventilation, one of which may be the supply...

46 CFR 111.103-3 - Machinery space ventilation.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 4 2010-10-01 2010-10-01 false Machinery space ventilation. 111.103-3 Section 111.103-3...-GENERAL REQUIREMENTS Remote Stopping Systems § 111.103-3 Machinery space ventilation. (a) Each machinery space ventilation system must have two controls to stop the ventilation, one of which may be the supply...

Saturation of SERCA's lipid annulus may protect against its thermal inactivation

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

Fajardo, Val Andrew; Center for Bone and Muscle Health, Brock University, St. Catharines, ON; Department of Health Sciences, Brock University, St. Catharines, ON

The sarco(endo)plasmic reticulum Ca{sup 2+}-ATPase (SERCA) pumps are integral membrane proteins that catalyze the active transport of Ca{sup 2+} into the sarcoplasmic reticulum, thereby eliciting muscle relaxation. SERCA pumps are highly susceptible to oxidative damage, and cytoprotection of SERCA dampens thermal inactivation and is a viable therapeutic strategy in combating diseases where SERCA activity is impaired, such as muscular dystrophy. Here, we sought to determine whether increasing the percent of saturated fatty acids (SFA) within SERCA's lipid annulus through diet could protect SERCA pumps from thermal inactivation. Female Wistar rats were fed either a semi-purified control diet (AIN93G, 7% soybeanmore » oil by weight) or a modified AIN93G diet containing high SFA (20% lard by weight) for 17 weeks. Soleus muscles were extracted and SERCA lipid annulus and activity under thermal stress were analyzed. Our results show that SERCA's lipid annulus is abundant with short-chain (12–14 carbon) fatty acids, which corresponds well with SERCA's predicted bilayer thickness of 21 Å. Under control-fed conditions, SERCA's lipid annulus was already highly saturated (79%), and high-fat feeding did not increase this any further. High-fat feeding did not mitigate the reductions in SERCA activity seen with thermal stress; however, correlational analyses revealed significant and strong associations between % SFA and thermal stability of SERCA activity with greater %SFA being associated with lower thermal inactivation and greater % polyunsaturation and unsaturation index being associated with increased thermal inactivation. Altogether, these findings show that SERCA's lipid annulus may influence its susceptibility to oxidative damage, which could have implications in muscular dystrophy and age-related muscle wasting. - Highlights: • SERCA's lipid annulus in rat soleus was measured after immunoconcentration. • Short fatty acid chains surround SERCA and may ensure optimal hydrophobic matching. • SERCA's annulus is highly saturated in control-fed and high-fat fed rats. • Greater saturation associates with small levels of thermal inactivation. • Greater unsaturation associates with large levels of thermal inactivation.« less

Tricuspid Annular Geometry: A Three-Dimensional Transesophageal Echocardiographic Study

PubMed Central

Mahmood, Feroze; Kim, Han; Chaudary, Bilal; Bergman, Remco; Matyal, Robina; Gerstle, Jeniffer; Gorman, Joseph H.; Gorman, Robert C.; Khabbaz, Kamal R.

2013-01-01

Objective To demonstrate the clinical feasibility of accurately measuring tricuspid annular area by 3-dimensional (3D) transesophageal echocardiography (TEE) and to assess the geometric differences based on the presence of tricuspid regurgitation (TR). Also, the shape of the tricuspid annulus was compared with previous descriptions in the literature. Design Prospective. Setting Tertiary care university hospital. Interventions Three-dimensional TEE. Participants Patients undergoing cardiac surgery. Measurements and Main Results Volumetric data sets from 20 patients were acquired by 3D TEE and prospectively analyzed. Comparisons in annular geometry were made between groups based on the presence of TR. The QLab (Philips Medical Systems, Andover, MA) software package was used to calculate tricuspid annular area by both linear elliptical dimensions and planimetry. Further analyses were performed in the 4D Cardio-View (TomTec Corporation GmBH, Munich, Germany) and MATLAB (Natick, MA) software environments to accurately assess annular shape. It was found that patients with greater TR had an eccentrically dilated annulus with a larger annular area. Also, the area as measured by the linear ellipse method was overestimated as compared to the planimetry method. Furthermore, the irregular saddle-shaped geometry of the tricuspid annulus was confirmed through the mathematic model developed by the authors. Conclusions Three-dimensional TEE can be used to measure the tricuspid annular area in a clinically feasible fashion, with an eccentric dilation seen in patients with TR. The tricuspid annulus shape is complex, with annular high and low points, and annular area calculation based on linear measurements significantly overestimates 3D planimetered area. PMID:23725682

Manual, semiautomated, and fully automated measurement of the aortic annulus for planning of transcatheter aortic valve replacement (TAVR/TAVI): analysis of interchangeability.

PubMed

Lou, Junyang; Obuchowski, Nancy A; Krishnaswamy, Amar; Popovic, Zoran; Flamm, Scott D; Kapadia, Samir R; Svensson, Lars G; Bolen, Michael A; Desai, Milind Y; Halliburton, Sandra S; Tuzcu, E Murat; Schoenhagen, Paul

2015-01-01

Preprocedural 3-dimensional CT imaging of the aortic annular plane plays a critical role for transcatheter aortic valve replacement (TAVR) planning; however, manual reconstructions are complex. Automated analysis software may improve reproducibility and agreement between readers but is incompletely validated. In 110 TAVR patients (mean age, 81 years; 37% female) undergoing preprocedural multidetector CT, automated reconstruction of the aortic annular plane and planimetry of the annulus was performed with a prototype of now commercially available software (syngo.CT Cardiac Function-Valve Pilot; Siemens Healthcare, Erlangen, Germany). Fully automated, semiautomated, and manual annulus measurements were compared. Intrareader and inter-reader agreement, intermodality agreement, and interchangeability were analyzed. Finally, the impact of these measurements on recommended valve size was evaluated. Semiautomated analysis required major correction in 5 patients (4.5%). In the remaining 95.5%, only minor correction was performed. Mean manual annulus area was significantly smaller than fully automated results (P < .001 for both readers) but similar to semiautomated measurements (5.0 vs 5.4 vs 4.9 cm(2), respectively). The frequency of concordant recommendations for valve size increased if manual analysis was replaced with the semiautomated method (60% agreement was improved to 82.4%; 95% confidence interval for the difference [69.1%-83.4%]). Semiautomated aortic annulus analysis, with minor correction by the user, provides reliable results in the context of TAVR annulus evaluation. Copyright © 2015 Society of Cardiovascular Computed Tomography. Published by Elsevier Inc. All rights reserved.

VENTILATION TECHNOLOGY SYSTEMS ANALYSIS

EPA Science Inventory

The report gives results of a project to develop a systems analysis of ventilation technology and provide a state-of-the-art assessment of ventilation and indoor air quality (IAQ) research needs. (NOTE: Ventilation technology is defined as the hardware necessary to bring outdoor ...

On the Use of Biaxial Properties in Modeling Annulus as a Holzapfel–Gasser–Ogden Material

PubMed Central

Momeni Shahraki, Narjes; Fatemi, Ali; Goel, Vijay K.; Agarwal, Anand

2015-01-01

Besides the biology, stresses and strains within the tissue greatly influence the location of damage initiation and mode of failure in an intervertebral disk. Finite element models of a functional spinal unit (FSU) that incorporate reasonably accurate geometry and appropriate material properties are suitable to investigate such issues. Different material models and techniques have been used to model the anisotropic annulus fibrosus, but the abilities of these models to predict damage initiation in the annulus and to explain clinically observed phenomena are unclear. In this study, a hyperelastic anisotropic material model for the annulus with two different sets of material constants, experimentally determined using uniaxial and biaxial loading conditions, were incorporated in a 3D finite element model of a ligamentous FSU. The purpose of the study was to highlight the biomechanical differences (e.g., intradiscal pressure, motion, forces, stresses, strains, etc.) due to the dissimilarity between the two sets of material properties (uniaxial and biaxial). Based on the analyses, the biaxial constants simulations resulted in better agreements with the in vitro and in vivo data, and thus are more suitable for future damage analysis and failure prediction of the annulus under complex multiaxial loading conditions. PMID:26090359

Multidimensional Mixing Behavior of Steam-Water Flow in a Downcomer Annulus During LBLOCA Reflood Phase with a Direct Vessel Injection Mode

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

Kwon, Tae-Soon; Yun, Byong-Jo; Euh, Dong-Jin

Multidimensional thermal-hydraulic behavior in the downcomer annulus of a pressurized water reactor (PWR) vessel with a direct vessel injection mode is presented based on the experimental observation in the MIDAS (multidimensional investigation in downcomer annulus simulation) steam-water test facility. From the steady-state test results to simulate the late reflood phase of a large-break loss-of-coolant accident (LBLOCA), isothermal lines show the multidimensional phenomena of a phasic interaction between steam and water in the downcomer annulus very well. MIDAS is a steam-water separate effect test facility, which is 1/4.93 linearly scaled down to a 1400-MW(electric) PWR type of a nuclear reactor, focusedmore » on understanding multidimensional thermal-hydraulic phenomena in a downcomer annulus with various types of safety injection during the refill or reflood phase of an LBLOCA. The initial and the boundary conditions are scaled from the pretest analysis based on the preliminary calculation using the TRAC code. The superheated steam with a superheating degree of 80 K at a given downcomer pressure of 180 kPa is injected equally through three intact cold legs into the downcomer.« less

Surface hydrogenation regulated wrinkling and torque capability of hydrogenated graphene annulus under circular shearing.

PubMed

Li, Yinfeng; Liu, Silin; Datta, Dibakar; Li, Zhonghua

2015-11-12

Wrinkles as intrinsic topological feature have been expected to affect the electrical and mechanical properties of atomically thin graphene. Molecular dynamics simulations are adopted to investigate the wrinkling characteristics in hydrogenated graphene annulus under circular shearing at the inner edge. The amplitude of wrinkles induced by in-plane rotation around the inner edge is sensitive to hydrogenation, and increases quadratically with hydrogen coverage. The effect of hydrogenation on mechanical properties is investigated by calculating the torque capability of annular graphene with varying hydrogen coverage and inner radius. Hydrogenation-enhanced wrinkles cause the aggregation of carbon atoms towards the inner edge and contribute to the critical torque strength of annulus. Based on detailed stress distribution contours, a shear-to-tension conversion mechanism is proposed for the contribution of wrinkles on torque capacity. As a result, the graphane annulus anomalously has similar torque capacity to pristine graphene annulus. The competition between hydrogenation caused bond strength deterioration and wrinkling induced local stress state conversion leads to a U-shaped evolution of torque strength relative to the increase of hydrogen coverage from 0 to 100%. Such hydrogenation tailored topological and mechanical characteristics provides an innovative mean to develop novel graphene-based devices.

Correlating heat and mass transfer coefficients for thermosolutal convection within a porous annulus of a circular shape: case of internal pollutants spreading

NASA Astrophysics Data System (ADS)

Ragui, Karim; Boutra, Abdelkader; Bennacer, Rachid; Labsi, Nabila; Benkahla, Youb Khaled

2018-07-01

The main purpose of our investigation is to show the impact of pertinent parameters; such Lewis and porous thermal Rayleigh numbers as well as the buoyancy and the aspect ratios; on the double-diffusive convection phenomena which occur within a porous annulus; found between a cold (and less concentric) outer circular cylinder and a hot (and concentric) inner one, to come out with global correlations which predict the mean transfer rates in such annulus. To do so, the physical model for the momentum conservation equation is made using the Brinkman extension of the classical Darcy equation. The set of coupled equations is solved using the finite volume method and the SIMPLER algorithm. Summarizing the numerical predictions, global correlations of overall transfer within the porous annulus as a function of the governing studied parameters are set forth which predict within ±2% the numerical results. These correlations may count as a complement to previous researches done in the case a Newtonian-fluid annulus. It is to note that the validity of the computing code used was ascertained by comparing our results with the experimental data and numerical ones already available in the literature.

Correlating heat and mass transfer coefficients for thermosolutal convection within a porous annulus of a circular shape: case of internal pollutants spreading

NASA Astrophysics Data System (ADS)

Ragui, Karim; Boutra, Abdelkader; Bennacer, Rachid; Labsi, Nabila; Benkahla, Youb Khaled

2018-02-01

The main purpose of our investigation is to show the impact of pertinent parameters; such Lewis and porous thermal Rayleigh numbers as well as the buoyancy and the aspect ratios; on the double-diffusive convection phenomena which occur within a porous annulus; found between a cold (and less concentric) outer circular cylinder and a hot (and concentric) inner one, to come out with global correlations which predict the mean transfer rates in such annulus. To do so, the physical model for the momentum conservation equation is made using the Brinkman extension of the classical Darcy equation. The set of coupled equations is solved using the finite volume method and the SIMPLER algorithm. Summarizing the numerical predictions, global correlations of overall transfer within the porous annulus as a function of the governing studied parameters are set forth which predict within ±2% the numerical results. These correlations may count as a complement to previous researches done in the case a Newtonian-fluid annulus. It is to note that the validity of the computing code used was ascertained by comparing our results with the experimental data and numerical ones already available in the literature.

Effects of types of ventilation system on indoor particle concentrations in residential buildings.

PubMed

Park, J S; Jee, N-Y; Jeong, J-W

2014-12-01

The objective of this study was to quantify the influence of ventilation systems on indoor particle concentrations in residential buildings. Fifteen occupied, single-family apartments were selected from three sites. The three sites have three different ventilation systems: unbalanced mechanical ventilation, balanced mechanical ventilation, and natural ventilation. Field measurements were conducted between April and June 2012, when outdoor air temperatures were comfortable. Number concentrations of particles, PM2.5 and CO2 , were continuously measured both outdoors and indoors. In the apartments with natural ventilation, I/O ratios of particle number concentrations ranged from 0.56 to 0.72 for submicron particles, and from 0.25 to 0.60 for particles larger than 1.0 μm. The daily average indoor particle concentration decreased to 50% below the outdoor level for submicron particles and 25% below the outdoor level for fine particles, when the apartments were mechanically ventilated. The two mechanical ventilation systems reduced the I/O ratios by 26% for submicron particles and 65% for fine particles compared with the natural ventilation. These results showed that mechanical ventilation can reduce exposure to outdoor particles in residential buildings. Results of this study confirm that mechanical ventilation with filtration can significantly reduce indoor particle levels compared with natural ventilation. The I/O ratios of particles substantially varied at the naturally ventilated apartments because of the influence of variable window opening conditions and unsteadiness of wind flow on the penetration of outdoor air particles. For better prediction of the exposure to outdoor particles in naturally ventilated residential buildings, it is important to understand the penetration of outdoor particles with variable window opening conditions. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

The papillary muscles as shock absorbers of the mitral valve complex. An experimental study.

PubMed

Joudinaud, Thomas M; Kegel, Corrine L; Flecher, Erwan M; Weber, Patricia A; Lansac, Emmanuel; Hvass, Ulrich; Duran, Carlos M G

2007-07-01

Although it is known that the papillary muscles ensure the continuity between the left ventricle (LV) and the mitral apparatus, their precise mechanism needs further study. We hypothesize that the papillary muscles function as shock absorbers to maintain a constant distance between their tips and the mitral annulus during the entire cardiac cycle. Sonomicrometry crystals were implanted in five sheep in the mitral annulus at the trigones (T1 and T2), mid anterior annulus (AA) mid posterior annulus (PA), base of the posterior lateral scallops (P1 and P2), tips of papillary muscles (M1 and M2), and LV apex. LV and aortic pressures were simultaneously recorded and used to define the different phases of the cardiac cycle. No significant distance changes were found during the cardiac cycle between each papillary muscle tip and their corresponding mitral hemi-annulus: M1-T1, (3.5+/-2%); M1-P1 (5+/-2%); M1-PA (5+/-3%); M2-T2 (2.7+/-2%); M2-P2 (6.1+/-3%); and M2-AA (4.2+/-3%); (p>0.05, ANOVA). Significant changes were observed in distances between each papillary muscle tip and the contralateral hemi-mitral annulus: M1-T2 (1.7+/-3%); M1-P2 (23+/-6%); M1-AA (6+/-3%); M2-T1 (8+/-3%); M2-P1 (10.5+/-6%); and M2-PA (12.6+/-8%); (p<0.05 ANOVA). The distance changes between LV apex and each papillary muscle tip were significantly different: apex-M1 (12.9+/-1%) and apex-M2 (10.5+/-1%) and different from the averaged distance change between the LV apex and each annulus crystal (8.3+/-1%) with p<0.05. The papillary muscles seem to be independent mechanisms designed to work as shock absorbers to maintain the basic mitral valve geometry constant during the cardiac cycle.

Noise suppression due to annulus shaping of an inverted-velocity-profile coaxial nozzle. [supersonic cruise aircraft

NASA Technical Reports Server (NTRS)

Goodykoontz, J.; Vonglahn, U.

1980-01-01

An inverted velocity profile coaxial nozzle for use with supersonic cruise aircraft produces less jet noise than an equivalent conical nozzle. Furthermore, decreasing the annulus height (increasing radius ratio with constant flow) results in further noise reduction benefits. The annulus shape (height) was varied by an eccentric mounting of the annular nozzle with respect to a conical core nozzle. Acoustic measurements were made in the flyover plane below the narrowest portion of the annulus and at 90 deg and 180 deg from this point. The model-scale spectra are scaled up to engine size (1.07 m diameter) and the perceived noise levels for the eccentric and baseline concentric inverted velocity profile coaxial nozzles are compared over a range of operating conditions. The implications of the acoustic benefits derived with the eccentric nozzle to practical applications are discussed.

Radial flow pulse jet mixer

DOEpatents

VanOsdol, John G.

2013-06-25

The disclosure provides a pulse jet mixing vessel for mixing a plurality of solid particles. The pulse jet mixing vessel is comprised of a sludge basin, a flow surface surrounding the sludge basin, and a downcoming flow annulus between the flow surface and an inner shroud. The pulse jet mixing vessel is additionally comprised of an upper vessel pressurization volume in fluid communication with the downcoming flow annulus, and an inner shroud surge volume separated from the downcoming flow annulus by the inner shroud. When the solid particles are resting on the sludge basin and a fluid such as water is atop the particles and extending into the downcoming flow annulus and the inner shroud surge volume, mixing occurs by pressurization of the upper vessel pressurization volume, generating an inward radial flow over the flow surface and an upwash jet at the center of the sludge basin.

Method of well testing

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

Ringgenberg, P.D.; Burris, W.J.

1988-06-28

A method is described of flow testing a formation in a wellbore, comprising: providing a testing string including at least one annulus pressure responsive tool bore closure valve; providing a packer and setting the packer in the wellbore to seal thereacross; running the testing string into the wellbore with the tool bore closure valve in an open position; stinging into the set packer with the bottom of the testing string; increasing pressure a first time in the wellbore annulus around the testing string and above the set packer without cycling the tool bore closure valve; reducing pressure in the wellboremore » annulus; closing the tool bore closure valve responsive to the pressure reduction; increasing pressure a second time in the wellbore annulus; reopening the tool bore closure valve responsive to the second increase; and flowing fluids from the formation through the reopened tool bore closure valve.« less

Software Configuration Management Plan for the B-Plant Canyon Ventilation Control System

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

MCDANIEL, K.S.

1999-08-31

Project W-059 installed a new B Plant Canyon Ventilation System. Monitoring and control of the system is implemented by the Canyon Ventilation Control System (CVCS). This Software Configuration Management Plan provides instructions for change control of the CVCS.

Anaesthesia ventilators.

PubMed

Jain, Rajnish K; Swaminathan, Srinivasan

2013-09-01

Anaesthesia ventilators are an integral part of all modern anaesthesia workstations. Automatic ventilators in the operating rooms, which were very simple with few modes of ventilation when introduced, have become very sophisticated with many advanced ventilation modes. Several systems of classification of anaesthesia ventilators exist based upon various parameters. Modern anaesthesia ventilators have either a double circuit, bellow design or a single circuit piston configuration. In the bellows ventilators, ascending bellows design is safer than descending bellows. Piston ventilators have the advantage of delivering accurate tidal volume. They work with electricity as their driving force and do not require a driving gas. To enable improved patient safety, several modifications were done in circle system with the different types of anaesthesia ventilators. Fresh gas decoupling is a modification done in piston ventilators and in descending bellows ventilator to reduce th incidence of ventilator induced volutrauma. In addition to the conventional volume control mode, modern anaesthesia ventilators also provide newer modes of ventilation such as synchronised intermittent mandatory ventilation, pressure-control ventilation and pressure-support ventilation (PSV). PSV mode is particularly useful for patients maintained on spontaneous respiration with laryngeal mask airway. Along with the innumerable benefits provided by these machines, there are various inherent hazards associated with the use of the ventilators in the operating room. To use these workstations safely, it is important for every Anaesthesiologist to have a basic understanding of the mechanics of these ventilators and breathing circuits.

Changes in Mitral Annular Geometry after Aortic Valve Replacement: A Three-Dimensional Transesophageal Echocardiographic Study

PubMed Central

Mahmood, Feroze; Warraich, Haider J.; Gorman, Joseph H.; Gorman, Robert C.; Chen, Tzong-Huei; Panzica, Peter; Maslow, Andrew; Khabbaz, Kamal

2014-01-01

Background and aim of the study Intraoperative real-time three-dimensional transesophageal echocardiography (RT-3D TEE) was used to examine the geometric changes that occur in the mitral annulus immediately after aortic valve replacement (AVR). Methods A total of 35 patients undergoing elective surgical AVR under cardiopulmonary bypass was enrolled in the study. Intraoperative RT-3D TEE was used prospectively to acquire volumetric echocardiographic datasets immediately before and after AVR. The 3D echocardiographic data were analyzed offline using TomTec® Mitral Valve Assessment software to assess changes in specific mitral annular geometric parameters. Results Datasets were successfully acquired and analyzed for all patients. A significant reduction was noted in the mitral annular area (-16.3%, p <0.001), circumference (-8.9% p <0.001) and the anteroposterior (-6.3%, p = 0.019) and anterolateral-posteromedial (-10.5%, p <0.001) diameters. A greater reduction was noted in the anterior annulus length compared to the posterior annulus length (10.5% versus 62%, p <0.05) after AVR. No significant change was seen in the non-planarity angle, coaptation depth, and closure line length. During the period of data acquisition before and after AVR, no significant change was noted in the central venous pressure or left ventricular end-diastolic diameter. Conclusion The mitral annulus undergoes significant geometric changes immediately after AVR Notably, a 16.3% reduction was observed in the mitral annular area. The anterior annulus underwent a greater reduction in length compared to the posterior annulus, which suggested the existence of a mechanical compression by the prosthetic valve. PMID:23409347

The Lawn Hill annulus: An Ordovician meteorite impact into water-saturated dolomite

NASA Astrophysics Data System (ADS)

Darlington, Vicki; Blenkinsop, Tom; Dirks, Paul; Salisbury, Jess; Tomkins, Andrew

2016-12-01

The Lawn Hill Impact Structure (LHIS) is located 250 km N of Mt Isa in NW Queensland, Australia, and is marked by a highly deformed dolomite annulus with an outer diameter of 18 km, overlying low metamorphic grade siltstone, sandstone, and shale, along the NE margin of the Georgina Basin. This study provides detailed field observations from sections of the Lawn Hill annulus and adjacent areas that demonstrate a clear link between the deformation of the dolomite and the Lawn Hill impact. 40Ar-39Ar dating of impact-related melt particles provides a time of impact in the Ordovician (472 ± 8 Ma) when the Georgina Basin was an active depocenter. The timing and stratigraphic thickness of the dolomite sequence in the annulus suggest that there was possibly up to 300 m of additional sedimentary rocks on top of the currently exposed Thorntonia Limestone at the time of impact. The exposed annulus is remarkably well preserved, with preservation attributed to postimpact sedimentation. The LHIS has an atypical crater morphology with no central uplift. The heterogeneous target materials at Lawn Hill were probably low-strength, porous, and water-saturated, with all three properties affecting the crater morphology. The water-saturated nature of the carbonate unit at the time of impact is thought to have influenced the highly brecciated nature of the annulus, and restricted melt production. The impact timing raises the possibility that the Lawn Hill structure may be a member of a group of impacts resulting from an asteroid breakup that occurred in the mid-Ordovician (470 ± 6 Ma).

Jet-front systems nearing strongly stratified region in differentially heated, rotating stratified annulus

NASA Astrophysics Data System (ADS)

Rolland, Joran; Achatz, Ulrich

2017-04-01

The differentially heated, rotating annulus configuration has been used for a long time as a model system of the earth troposphere. It can easily reproduce thermal wind and baroclinic waves in the laboratory. It has recently been shown numerically that provided the Rossby number, the rotation rate and the Brunt-Väisälä frequency were well chosen, this configuration also reproduces the spontaneous emission of gravity waves by jet front systems [1]. This offers a very practical configuration in which to study an important process of emission of atmospheric gravity waves. It has also been shown experimentally that this configuration can be modified in order to add the possibility for the emitted wave to reach a strongly stratified region [2]. It thus creates a system containing a model troposphere where gravity waves are spontaneously emitted and can propagate to a model stratosphere. For this matter a stratification was created using a salinity gradient in the experimental apparatus. Through double diffusion, this generates a strongly stratified layer in the middle of the flow (the model stratosphere) and two weakly stratified region in the top and bottom layers (the model troposphere). In this poster, we present simulations of this configuration displaying baroclinic waves in the top and bottom layers. We aim at creating jet front systems strong enough that gravity waves can be spontaneously emitted. This will thus offer the possibility of studying the wave characteristic and mechanisms in emission and propagation in details. References [1] S. Borchert, U. Achatz, M.D. Fruman, Spontaneous Gravity wave emission in the differentially heated annulus, J. Fluid Mech. 758, 287-311 (2014). [2] M. Vincze, I. Borcia, U. Harlander, P. Le Gal, Double-diffusive convection convection and baroclinic instability in a differentially heated and initially stratified rotating system: the barostrat instability, Fluid Dyn. Res. 48, 061414 (2016).

46 CFR 111.106-15 - Ventilation of hazardous locations.

Code of Federal Regulations, 2014 CFR

2014-10-01

... its operational controls outside the ventilated space, if the system is mechanical; and (3) Have a... opening. (c) The mechanical ventilation of enclosed flammable or combustible liquid cargo handling or.... The power ventilation system must be designed to remove vapors from the bottom of the space at points...

Downflow dryout in a heated ribbed vertical annulus with a cosine power profile (Results from test series ECS-2, WSR, and ECS-2cE)

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

Larson, T.K.; Anderson, J.L.; Condie, K.G.

Experiments designed to investigate surface dryout in a heated, ribbed annulus test section simulating one of the annular coolant channels of a Savannah River Plant production reactor Mark 22 fuel assembly have been conducted at the Idaho National Engineering Laboratory. The inner surface of the annulus was constructed of aluminum and was electrically heated to provide an axial cosine power profile and a flat azimuthal power shape. Data presented in this report are from the ECS-2, WSR, and ECS-2cE series of tests. These experiments were conducted to examine the onset of wall thermal excursion for a range of flow, inletmore » fluid temperature, and annulus outlet pressure. Hydraulic boundary conditions on the test section represent flowrates (0.1--1.4 1/s), inlet fluid temperatures (293--345 K), and outlet pressures (-18--139.7 cm of water relative to the bottom of the heated length (61--200 cm of water relative to the bottom of the lower plenum)) expected to occur during the Emergency Coolant System (ECS) phase of postulated Loss-of-Coolant Accident in a production reactor. The onset of thermal excursion based on the present data is consistent with data gathered in test rigs with flat axial power profiles. The data indicate that wall dryout is primarily a function of liquid superficial velocity. Air entrainment rate was observed to be a strong function of the boundary conditions (primarily flowrate and liquid temperature), but had a minor effect on the power at the onset of thermal excursion for the range of conditions examined. 14 refs., 33 figs., 13 tabs.« less

A composites-based hyperelastic constitutive model for soft tissue with application to the human annulus fibrosus

NASA Astrophysics Data System (ADS)

Guo, Z. Y.; Peng, X. Q.; Moran, B.

2006-09-01

This paper presents a composites-based hyperelastic constitutive model for soft tissue. Well organized soft tissue is treated as a composite in which the matrix material is embedded with a single family of aligned fibers. The fiber is modeled as a generalized neo-Hookean material in which the stiffness depends on fiber stretch. The deformation gradient is decomposed multiplicatively into two parts: a uniaxial deformation along the fiber direction and a subsequent shear deformation. This permits the fiber-matrix interaction caused by inhomogeneous deformation to be estimated by using effective properties from conventional composites theory based on small strain linear elasticity and suitably generalized to the present large deformation case. A transversely isotropic hyperelastic model is proposed to describe the mechanical behavior of fiber-reinforced soft tissue. This model is then applied to the human annulus fibrosus. Because of the layered anatomical structure of the annulus fibrosus, an orthotropic hyperelastic model of the annulus fibrosus is developed. Simulations show that the model reproduces the stress-strain response of the human annulus fibrosus accurately. We also show that the expression for the fiber-matrix shear interaction energy used in a previous phenomenological model is compatible with that derived in the present paper.

Mechanical Restoration and Failure Analyses of a Hydrogel and Scaffold Composite Strategy for Annulus Fibrosus Repair

PubMed Central

Long, Rose G; Bürki, Alexander; Zysset, Philippe; Eglin, David; Grijpma, Dirk W.; Blanquer, Sebastien BG; Hecht, Andrew C; Iatridis, James C

2015-01-01

Unrepaired defects in the annulus fibrosus of intervertebral discs are associated with degeneration and persistent back pain. A clinical need exists for a disc repair strategy that can seal annular defects, be easily delivered during surgical procedures, and restore biomechanics with low risk of herniation. Multiple annulus repair strategies were developed using poly(trimethylene carbonate) scaffolds optimized for cell delivery, polyurethane membranes designed to prevent herniation, and fibrin-genipin adhesive tuned to annulus fibrosus shear properties. This three-part study evaluated repair strategies for biomechanical restoration, herniation risk and failure mode in torsion, bending and compression at physiological and hyper-physiological loads using a bovine injury model. Fibrin-genipin hydrogel restored some torsional stiffness, bending ROM and disc height loss, with negligible herniation risk and failure was observed histologically at the fibrin-genipin mid-substance following rigorous loading. Scaffold-based repairs partially restored biomechanics, but had high herniation risk even when stabilized with sutured membranes and failure was observed histologically at the interface between scaffold and fibrin-genipin adhesive. Fibrin-genipin was the simplest annulus fibrosus repair solution evaluated that involved an easily deliverable adhesive that filled irregularly-shaped annular defects and partially restored disc biomechanics with low herniation risk, suggesting further evaluation for disc repair may be warranted. PMID:26577987

Replacing the nucleus pulposus of the intervertebral disk: prediction of suitable properties of a replacement material using finite element analysis.

PubMed

Meakin, J R

2001-03-01

An axisymmetric finite element model of a human lumbar disk was developed to investigate the properties required of an implant to replace the nucleus pulposus. In the intact disk, the nucleus was modeled as a fluid, and the annulus as an elastic solid. The Young's modulus of the annulus was determined empirically by matching model predictions to experimental results. The model was checked for sensitivity to the input parameter values and found to give reasonable behavior. The model predicted that removal of the nucleus would change the response of the annulus to compression. This prediction was consistent with experimental results, thus validating the model. Implants to fill the cavity produced by nucleus removal were modeled as elastic solids. The Poisson's ratio was fixed at 0.49, and the Young's modulus was varied from 0.5 to 100 MPa. Two sizes of implant were considered: full size (filling the cavity) and small size (smaller than the cavity). The model predicted that a full size implant would reverse the changes to annulus behavior, but a smaller implant would not. By comparing the stress distribution in the annulus, the ideal Young's modulus was predicted to be approximately 3 MPa. These predictions have implications for current nucleus implant designs. Copyright 2001 Kluwer Academic Publishers

Apodization of two-dimensional pupils with aberrations

NASA Astrophysics Data System (ADS)

Reddy, Andra Naresh Kumar; Hashemi, Mahdieh; Khonina, Svetlana Nikolaevna

2018-06-01

The technique proposed to enhance the resolution of the point spread function (PSF) of an optical system underneath defocussing and spherical aberrations. The method of approach is based on the amplitude and phase masking in a ring aperture for modifying the light intensity distribution in the Gaussian focal plane (YD = 0) and in the defocussed planes (YD= π and YD= 2π ). The width of the annulus modifies the distribution of the light intensity in the side lobes of the resultant PSF. In the presence of an asymmetry in the phase of the annulus, the Hanning amplitude apodizer [cos(π β ρ )] employed in the pupil function can modify the spatial distribution of light in the maximum defocussed plane ({Y}D = 2π ), results in PSF with improved resolution.

Core disruptive accident margin seal

DOEpatents

Garin, John

1978-01-01

An apparatus for sealing the annulus defined between a substantially cylindrical rotatable first riser assembly and plug combination disposed in a substantially cylindrical second riser assembly and plug combination of a nuclear reactor system. The apparatus comprises a flexible metal member having a first side attached to one of the riser components and a second side extending toward the other riser component and an actuating mechanism attached to the flexible metal member while extending to an accessible location. When the actuating mechanism is not activated, the flexible metal member does not contact the other riser component thus allowing the free rotation of the riser assembly and plug combination. When desired, the actuating mechanism causes the second side of the flexible metal member to contact the other riser component thereby sealing the annulus between the components.

46 CFR 153.310 - Ventilation system type.

Code of Federal Regulations, 2014 CFR

2014-10-01

... CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Design and Equipment Cargo Handling Space Ventilation § 153.310 Ventilation system type. A cargo handling space must have a permanent...

46 CFR 153.310 - Ventilation system type.

Code of Federal Regulations, 2010 CFR

2010-10-01

... CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Design and Equipment Cargo Handling Space Ventilation § 153.310 Ventilation system type. A cargo handling space must have a permanent...

46 CFR 153.310 - Ventilation system type.

Code of Federal Regulations, 2012 CFR

2012-10-01

... CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Design and Equipment Cargo Handling Space Ventilation § 153.310 Ventilation system type. A cargo handling space must have a permanent...

46 CFR 153.310 - Ventilation system type.

Code of Federal Regulations, 2011 CFR

2011-10-01

... CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Design and Equipment Cargo Handling Space Ventilation § 153.310 Ventilation system type. A cargo handling space must have a permanent...

46 CFR 153.310 - Ventilation system type.

Code of Federal Regulations, 2013 CFR

2013-10-01

... CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Design and Equipment Cargo Handling Space Ventilation § 153.310 Ventilation system type. A cargo handling space must have a permanent...

Improving indoor air quality through the use of continual multipoint monitoring of carbon dioxide and dew point.

PubMed

Bearg, D W

1998-09-01

This article summarizes an approach for improving the indoor air quality (IAQ) in a building by providing feedback on the performance of the ventilation system. The delivery of adequate quantities of ventilation to all building occupants is necessary for the achievement of good IAQ. Feedback on the performance includes information on the adequacy of ventilation provided, the effectiveness of the distribution of this air, the adequacy of the duration of operation of the ventilation system, and the identification of leakage into the return plenum, either of outdoor or supply air. Keeping track of ventilation system performance is important not only in terms of maintaining good IAQ, but also making sure that this system continues to perform as intended after changes in building use. Information on the performance of the ventilation system is achieved by means of an automated sampling system that draws air from multiple locations and delivers it to both a carbon dioxide monitor and dew point sensor. The use of single shared sensors facilitates calibration checks as well as helps to guarantee data integrity. This approach to monitoring a building's ventilation system offers the possibility of achieving sustainable performance of this important aspect of good IAQ.

Summary of human responses to ventilation.

PubMed

Seppänen, O A; Fisk, W J

2004-01-01

It is known that ventilation is necessary to remove indoor-generated pollutants from indoor air or dilute their concentration to acceptable levels. But as the limit values of all pollutants are not known the exact determination of required ventilation rates based on pollutant concentrations is seldom possible. The selection of ventilation rates has to be based also on epidemiological research, laboratory and field experiments and experience. The existing literature indicates that ventilation has a significant impact on several important human outcomes including: (1) communicable respiratory illnesses; (2) sick building syndrome symptoms; (3) task performance and productivity, and (4) perceived air quality (PAQ) among occupants or sensory panels (5) respiratory allergies and asthma. In many studies, prevalence of sick building syndrome symptoms has also been associated with characteristics of HVAC-systems. Often the prevalence of SBS symptoms is higher in air-conditioned buildings than in naturally ventilated buildings. The evidence suggests that better hygiene, commissioning, operation and maintenance of air handling systems may be particularly important for reducing the negative effects of HVAC systems. Ventilation may also have harmful effects on indoor air quality and climate if not properly designed, installed, maintained and operated. Ventilation may bring indoors harmful substances or deteriorate indoor environment. Ventilation interacts also with the building envelope and may deteriorate the structures of the building. Ventilation changes the pressure differences across the structures of building and may cause or prevent infiltration of pollutants from structures or adjacent spaces. Ventilation is also in many cases used to control the thermal environment or humidity in buildings. The paper summarises the current knowledge on positive and negative effects of ventilation on health and other human responses. The focus is on office-type working environment and residential buildings. The review shows that ventilation has various positive impacts on health and productivity of building occupants. Ventilation reduces the prevalence of airborne infectious diseases and thus the number of sick leave days. In office environment a ventilation rate up to 20-25 L/s per person seem to decrease the prevalence of SBS-symptoms. Air conditioning systems may increase the prevalence of SBS-symptoms relative to natural ventilation if not clean. In residential buildings the air change rate in cold climates should not be below app. 0.5 ach. Ventilation systems may cause pressure differences over the building envelope and bring harmful pollutants indoors.

Development of an Outdoor Temperature-Based Control Algorithm for Residential Mechanical Ventilation Control

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

Less, Brennan; Walker, Iain; Tang, Yihuan

2014-06-01

Smart ventilation systems use controls to ventilate more during those periods that provide either an energy or IAQ advantage (or both) and less during periods that provide a dis advantage. Using detailed building simulations, this study addresses one of the simplest and lowest cost types of smart controllers —outdoor temperature- based control. If the outdoor temperature falls below a certain cut- off, the fan is simply turned off. T he main principle of smart ventilation used in this study is to shift ventilation from time periods with large indoor -outdoor temperature differences, to periods where these differences are smaller, andmore » their energy impacts are expected to be less. Energy and IAQ performance are assessed relative to a base case of a continuously operated ventilation fan sized to comply with ASHRAE 62.2-2013 whole house ventilation requirements. In order to satisfy 62.2-2013, annual pollutant exposure must be equivalent between the temperature controlled and continuous fan cases. This requires ventilation to be greater than 62.2 requirements when the ventilation system operates. This is achieved by increasing the mechanical ventilation system air flow rates.« less

WASTE HANDLING BUILDING VENTILATION SYSTEM DESCRIPTION DOCUMENT

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

P.A. Kumar

2000-06-21

The Waste Handling Building Ventilation System provides heating, ventilation, and air conditioning (HVAC) for the contaminated, potentially contaminated, and uncontaminated areas of the Monitored Geologic Repository's (MGR) Waste Handling Building (WHB). In the uncontaminated areas, the non-confinement area ventilation system maintains the proper environmental conditions for equipment operation and personnel comfort. In the contaminated and potentially contaminated areas, in addition to maintaining the proper environmental conditions for equipment operation and personnel comfort, the contamination confinement area ventilation system directs potentially contaminated air away from personnel in the WHB and confines the contamination within high-efficiency particulate air (HEPA) filtration units. Themore » contamination confinement areas ventilation system creates airflow paths and pressure zones to minimize the potential for spreading contamination within the building. The contamination confinement ventilation system also protects the environment and the public by limiting airborne releases of radioactive or other hazardous contaminants from the WHB. The Waste Handling Building Ventilation System is designed to perform its safety functions under accident conditions and other Design Basis Events (DBEs) (such as earthquakes, tornadoes, fires, and loss of the primary electric power). Additional system design features (such as compartmentalization with independent subsystems) limit the potential for cross-contamination within the WHB. The system provides status of important system parameters and equipment operation, and provides audible and/or visual indication of off-normal conditions and equipment failures. The Waste Handling Building Ventilation System confines the radioactive and hazardous material within the building such that the release rates comply with regulatory limits. The system design, operations, and maintenance activities incorporate ALARA (as low as is reasonably achievable) principles to maintain personnel radiation doses to all occupational workers below regulatory limits and as low as is reasonably achievable. The Waste Handling Building Ventilation System interfaces with the Waste Handling Building System by being located within the WHB and by maintaining specific pressures, temperatures, and humidity within the building. The system also depends on the WHB for water supply. The system interfaces with the Site Radiological Monitoring System for continuous monitoring of the exhaust air; the Waste Handling Building Fire Protection System for detection of fire and smoke; the Waste Handling Building Electrical System for normal, emergency, and standby power; and the Monitored Geologic Repository Operations Monitoring and Control System for monitoring and control of the system.« less

Small aspect ratio Taylor-Couette flow: onset of a very-low-frequency three-torus state.

PubMed

Lopez, Juan M; Marques, Francisco

2003-09-01

The nonlinear dynamics of Taylor-Couette flow in a small aspect ratio annulus (where the length of the cylinders is half of the annular gap between them) is investigated by numerically solving the full three-dimensional Navier-Stokes equations. The system is invariant to arbitrary rotations about the annulus axis and to a reflection about the annulus half-height, so that the symmetry group is SO(2)xZ2. In this paper, we systematically investigate primary and subsequent bifurcations of the basic state, concentrating on a parameter regime where the basic state becomes unstable via Hopf bifurcations. We derive the four distinct cases for the symmetries of the bifurcated orbit, and numerically find two of these. In the parameter regime considered, we also locate the codimension-two double Hopf bifurcation where these two Hopf bifurcations coincide. Secondary Hopf bifurcations (Neimark-Sacker bifurcations), leading to modulated rotating waves, are subsequently found and a saddle-node-infinite-period bifurcation between a stable (node) and an unstable (saddle) modulated rotating wave is located, which gives rise to a very-low-frequency three-torus. This paper provides the computed example of such a state, along with a comprehensive bifurcation sequence leading to its onset.

Qualitative and quantitative assessment of collagen and elastin in annulus fibrosus of the physiologic and scoliotic intervertebral discs.

PubMed

Kobielarz, Magdalena; Szotek, Sylwia; Głowacki, Maciej; Dawidowicz, Joanna; Pezowicz, Celina

2016-09-01

The biophysical properties of the annulus fibrosus of the intervertebral disc are determined by collagen and elastin fibres. The progression of scoliosis is accompanied by a number of pathological changes concerning these structural proteins. This is a major cause of dysfunction of the intervertebral disc. The object of the study were annulus fibrosus samples excised from intervertebral discs of healthy subjects and patients treated surgically for scoliosis in the thoracolumbar or lumbar spine. The research material was subjected to structural analysis by light microscopy and quantitative analysis of the content of collagen types I, II, III and IV as well as elastin by immunoenzymatic test (ELISA). A statistical analysis was conducted to assess the impact of the sampling site (Mann-Whitney test, α=0.05) and scoliosis (Wilcoxon matched pairs test, α=0.05) on the obtained results. The microscopic studies conducted on scoliotic annulus fibrosus showed a significant architectural distortion of collagen and elastin fibres. Quantitative biochemical assays demonstrated region-dependent distribution of only collagen types I and II in the case of healthy intervertebral discs whereas in the case of scoliotic discs region-dependent distribution concerned all examined proteins of the extracellular matrix. Comparison of scoliotic and healthy annulus fibrosus revealed a significant decrease in the content of collagen type I and elastin as well as a slight increase in the proportion of collagen types III and IV. The content of collagen type II did not differ significantly between both groups. The observed anomalies are a manifestation of degenerative changes affecting annulus fibrosus of the intervertebral disc in patients suffering from scoliosis. Copyright © 2016 Elsevier Ltd. All rights reserved.

Primary limited lumbar discectomy with an annulus closure device: one-year clinical and radiographic results from a prospective, multi-center study.

PubMed

Lequin, Michiel B; Barth, Martin; Thomė, Claudius; Bouma, Gerrit J

2012-12-01

Discectomy as a treatment for herniated lumbar discs results in outcomes after surgery that are not uniformly positive. Surgeons face the dilemma between limited nucleus removal which is associated with a higher risk of recurrence, or more aggressive nucleus removal which may lead to disc height loss and persistent back-pain. annulus closure devices may allow for the benefits of limited nucleus removal without the increased risk of recurrence. This is an interim report of an ongoing 24-month post-marketing study of the Barricaid® annulus closure device, consisting of a flexible polymer mesh that blocks the defect, held in place by a titanium bone anchor. We prospectively enrolled 45 patients at four hospitals, and implanted the Barricaid® after a limited discectomy. annulus defect size and volume of removed nucleus were recorded. Reherniations were reported, pain and function were monitored and imaging was performed at regular intervals during 24 months of follow-up. At 12 months postsurgery, pain and function were significantly improved, comparing favorably to reported results from limited discectomy. Disc height has been well maintained. One reherniation has occurred (2.4%), which was associated with a misplaced device. No device fracture, subsidence or migration has been observed. The use of an annulus closure device may provide a reduction in reherniation rate for lumbar discectomy patients with large annulus defects who are at the greatest risk of recurrence. Using such a device should provide the surgeon increased confidence in minimizing nucleus removal, which, in turn, may preserve disc height and biomechanics, reducing degeneration and associated poor clinical outcomes in the long-term. A randomized multicenter study evaluating limited discectomy with and without the Barricaid® is currently underway, and will provide a higher level of evidence.

3D printing of the aortic annulus based on cardiovascular computed tomography: Preliminary experience in pre-procedural planning for aortic valve sizing.

PubMed

Faletti, Riccardo; Gatti, Marco; Cosentino, Aurelio; Bergamasco, Laura; Cura Stura, Erik; Garabello, Domenica; Pennisi, Giovanni; Salizzoni, Stefano; Veglia, Simona; Ottavio, Davini; Rinaldi, Mauro; Fonio, Paolo

2018-05-26

to determine reliability and reproducibility of measurements of aortic annulus in 3D models printed from cardiovascular computed tomography (CCT) images. Retrospective study on the records of 20 patients who underwent aortic valve replacement (AVR) with pre-surgery annulus assessment by CCT and intra-operative sizing by Hegar dilators (IOS). 3D models were fabricated by fused deposition modelling of thermoplastic polyurethane filaments. For each patient, two 3D models were independently segmented, modelled and printed by two blinded "manufacturers": a radiologist and a radiology technician. Two blinded cardiac surgeons performed the annulus diameter measurements by Hegar dilators on the two sets of models. Matched data from different measurements were analyzed with Wilcoxon test, Bland-Altmann plot and within-subject ANOVA. No significant differences were found among the measurements made by each cardiac surgeon on the same 3D model (p = 0.48) or on the 3D models printed by different manufacturers (p = 0.25); also, no intraobserver variability (p = 0.46). The annulus diameter measured on 3D models showed good agreement with the reference CCT measurement (p = 0.68) and IOH sizing (p = 0.11). Time and cost per model were: model creation ∼10-15 min; printing time ∼60 min; post-processing ∼5min; material cost ∼1€.
 CONCLUSION: 3D printing of aortic annulus can offer reliable, not expensive patient-specific information to be used in the pre-operative planning of AVR or transcatheter aortic valve implantation (TAVI). Copyright © 2018 Society of Cardiovascular Computed Tomography. Published by Elsevier Inc. All rights reserved.

Heating, Ventilation and Air-Conditioning Systems, Part of Indoor Air Quality Design Tools for Schools

EPA Pesticide Factsheets

The main purposes of a Heating, Ventilation, and Air-Conditioning system are to help maintain good indoor air quality through adequate ventilation with filtration and provide thermal comfort. HVAC systems are among the largest energy consumers in schools.

14 CFR 252.9 - Ventilation systems.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 4 2014-01-01 2014-01-01 false Ventilation systems. 252.9 Section 252.9 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF TRANSPORTATION (AVIATION PROCEEDINGS) ECONOMIC REGULATIONS SMOKING ABOARD AIRCRAFT § 252.9 Ventilation systems. Air carriers shall prohibit smoking whenever...

14 CFR 252.9 - Ventilation systems.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 4 2013-01-01 2013-01-01 false Ventilation systems. 252.9 Section 252.9 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF TRANSPORTATION (AVIATION PROCEEDINGS) ECONOMIC REGULATIONS SMOKING ABOARD AIRCRAFT § 252.9 Ventilation systems. Air carriers shall prohibit smoking whenever...

14 CFR 252.9 - Ventilation systems.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 4 2011-01-01 2011-01-01 false Ventilation systems. 252.9 Section 252.9 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF TRANSPORTATION (AVIATION PROCEEDINGS) ECONOMIC REGULATIONS SMOKING ABOARD AIRCRAFT § 252.9 Ventilation systems. Air carriers shall prohibit smoking whenever...

14 CFR 252.9 - Ventilation systems.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 4 2012-01-01 2012-01-01 false Ventilation systems. 252.9 Section 252.9 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF TRANSPORTATION (AVIATION PROCEEDINGS) ECONOMIC REGULATIONS SMOKING ABOARD AIRCRAFT § 252.9 Ventilation systems. Air carriers shall prohibit smoking whenever...

14 CFR 252.9 - Ventilation systems.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Ventilation systems. 252.9 Section 252.9 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF TRANSPORTATION (AVIATION PROCEEDINGS) ECONOMIC REGULATIONS SMOKING ABOARD AIRCRAFT § 252.9 Ventilation systems. Air carriers shall prohibit smoking whenever...

Design and calibration of a high-frequency oscillatory ventilator.

PubMed

Simon, B A; Mitzner, W

1991-02-01

High-frequency ventilation (HFV) is a modality of mechanical ventilation which presents difficult technical demands to the clinical or laboratory investigator. The essential features of an ideal HFV system are described, including wide frequency range, control of tidal volume and mean airway pressure, minimal dead space, and high effective internal impedance. The design and performance of a high-frequency oscillatory ventilation system is described which approaches these requirements. The ventilator utilizes a linear motor regulated by a closed loop controller and driving a novel frictionless double-diaphragm piston pump. Finally, the ventilator performance is tested using the impedance model of Venegas [1].

Labyrinth seal forces on a whirling rotor

NASA Technical Reports Server (NTRS)

Wright, D. V.

1983-01-01

An experimental investigation of air labyrinth seal forces on a subsynchronously whirling model rotor is described and test results are given for diverging, converging, and straight two-strip seals. The effects of pressure drop, provide basic experimental data needed in the development of design methods for predicting and preventing self-excited whirl of turbine rotors and other machines having labyrinth seals. The total dynamic seal forces on the whirling model rotor are measured accurately by means of an active damping and stiffness system that is adjusted to obtain neutral whirl stability of the model rotor system. In addition, the whirling pressure pattern in the seal annulus is measured for a few test conditions and the corresponding pressure forces on the rotor are compared with the total measured forces. This comparison shows that either radial and axial pressure gradients in the seal annulus or drag forces on the rotor are significant. Comparisons made between the measured seal forces and theoretical results show that present theory is inadequate.

ION GUN

DOEpatents

Dandl, R.A.

1961-10-24

An ion gun is described for the production of an electrically neutral ionized plasma. The ion gun comprises an anode and a cathode mounted in concentric relationship with a narrow annulus between. The facing surfaces of the rear portions of the anode and cathode are recessed to form an annular manifold. Positioned within this manifold is an annular intermediate electrode aligned with the an nulus between the anode and cathode. Gas is fed to the manifold and an arc discharge is established between the anode and cathode. The gas is then withdrawn from the manifold through the annulus between the anode and cathode by a pressure differential. The gas is then ionized by the arc discharge across the annulus. The ionized gas is withdrawn from the annulus by the combined effects of the pressure differential and a collimating magnetic field. In a 3000 gauss magnetic field, an arc voltage of 1800 volts, and an arc current of 0.2 amp, a plasma of about 3 x 10/sup 11/ particles/cc is obtained. (AEC)

In-line quincke tube muffler

NASA Astrophysics Data System (ADS)

Patrick, William P.; Bryant, Rebecca S.; Greenwald, Larry E.

2002-05-01

A unique low-pressure-drop muffler is described which has been designed to attenuate low frequency tonal noise in ducts. Flow through the muffler is divided into two noncommunicating paths in the cylindrical configuration which was designed, built, and tested. Half of the flow is ducted through a straight central annulus and the other half is ducted through a partitioned outer annulus which directs the flow in a spiral flow pattern around the inner annulus. Thus the outer flow has a longer path length and the sound within the outer annulus is phase-delayed relative to the inner flow causing destructive interference between the inner and outer waves with resulting strong attenuation at the tuned frequencies. A procedure will be described for designing a muffler (with flow) to produce high attenuation at the fundamental noise tone and all harmonics (up to the first cross mode). Results will be presented which show that the muffler achieved over 20 dB attenuation for the first five harmonics of the incident noise in a flowing duct.

Automatic detection of cardiac cycle and measurement of the mitral annulus diameter in 4D TEE images

NASA Astrophysics Data System (ADS)

Graser, Bastian; Hien, Maximilian; Rauch, Helmut; Meinzer, Hans-Peter; Heimann, Tobias

2012-02-01

Mitral regurgitation is a wide spread problem. For successful surgical treatment quantification of the mitral annulus, especially its diameter, is essential. Time resolved 3D transesophageal echocardiography (TEE) is suitable for this task. Yet, manual measurement in four dimensions is extremely time consuming, which confirms the need for automatic quantification methods. The method we propose is capable of automatically detecting the cardiac cycle (systole or diastole) for each time step and measuring the mitral annulus diameter. This is done using total variation noise filtering, the graph cut segmentation algorithm and morphological operators. An evaluation took place using expert measurements on 4D TEE data of 13 patients. The cardiac cycle was detected correctly on 78% of all images and the mitral annulus diameter was measured with an average error of 3.08 mm. Its full automatic processing makes the method easy to use in the clinical workflow and it provides the surgeon with helpful information.

Noise suppression due to annulus shaping of conventional coaxial nozzle

NASA Technical Reports Server (NTRS)

Vonglahn, U.; Goodykoontz, J.

1980-01-01

A method which shows that increasing the annulus width of a conventional coaxial nozzle with constant bypass velocity will lower the noise level is described. The method entails modifying a concentric coaxial nozzle to provide an eccentric outer stream annulus while maintaining approximately the same through flow as that for the original concentric bypass nozzle. Acoustical tests to determine the noise generating characteristics of the nozzle over a range of flow conditions are described. The tests involved sequentially analyzing the noise signals and digitally recording the 1/3 octave band sound pressure levels. The measurements were made in a plane passing through the minimum and maximum annulus width points, as well as at 90 degrees in this plane, by rotating the outer nozzle about its axis. Representative measured spectral data in the flyover plane for the concentric nozzle obtained at model scale are discussed. Representative spectra for several engine cycles are presented for both the eccentric and concentric nozzles at engine size.

CFD modelling of liquid-solid transport in the horizontal eccentric annuli

NASA Astrophysics Data System (ADS)

Sayindla, Sneha; Challabotla, Niranjan Reddy

2017-11-01

In oil and gas drilling operations, different types of drilling fluids are used to transport the solid cuttings in an annulus between drill pipe and well casing. The inner pipe is often eccentric and flow inside the annulus can be laminar or turbulent regime. In the present work, Eulerian-Eulerian granular multiphase CFD model is developed to systematically investigate the effect of the rheology of the drilling fluid type (Newtonian and non-Newtonian), drill pipe eccentricity and inner pipe rotation on the efficiency of cuttings transport. Both laminar and turbulent flow regimes were considered. Frictional pressure drop is computed and compared with the flow loop experimental results reported in the literature. The results confirm that the annular frictional pressure loss in a fully eccentric annulus are significantly lesser than the concentric annulus. Inner pipe rotation improve the efficiency of the cuttings transport in laminar flow regime. Cuttings transport velocity and concentration distribution were analysed to predict the different flow patterns such as stationary bed, moving bed, heterogeneous and homogeneous bed formation.

Inspiratory capacity at inflation hold in ventilated newborns: a surrogate measure for static compliance of the respiratory system.

PubMed

Hentschel, Roland; Semar, Nicole; Guttmann, Josef

2012-09-01

To study appropriateness of respiratory system compliance calculation using an inflation hold and compare it with ventilator readouts of pressure and tidal volume as well as with measurement of compliance of the respiratory system with the single-breath-single-occlusion technique gained with a standard lung function measurement. Prospective clinical trial. Level III neonatal unit of a university hospital. Sixty-seven newborns, born prematurely or at term, ventilated for a variety of pathologic conditions. A standardized sigh maneuver with a predefined peak inspiratory pressure of 30 cm H2O, termed inspiratory capacity at inflation hold, was applied. Using tidal volume, exhaled from inspiratory pause down to ambient pressure, as displayed by the ventilator, and predefined peak inspiratory pressure, compliance at inspiratory capacity at inflation hold conditions could be calculated as well as ratio of tidal volume and ventilator pressure using tidal volume and differential pressure at baseline ventilator settings: peak inspiratory pressure minus positive end-expiratory pressure. For the whole cohort, the equation for the regression between tidal volume at inspiratory capacity at inflation hold and compliance of the respiratory system was: compliance of the respiratory system = 0.052 * tidal volume at inspiratory capacity at inflation hold - 0.113, and compliance at inspiratory capacity at inflation hold conditions was closely related to the standard lung function measurement method of compliance of the respiratory system (R = 0.958). In contrast, ratio of tidal volume and ventilator pressure per kilogram calculated from the ventilator readouts and displayed against compliance of the respiratory system per kilogram yielded a broad scatter throughout the whole range of compliance; both were only weakly correlated (R = 0.309) and also the regression line was significantly different from the line of identity (p < .05). Peak inspiratory pressure at study entry did not affect the correlation between compliance at inspiratory capacity at inflation hold conditions and compliance of the respiratory system. After a standard sigh maneuver, inspiratory capacity at inflation hold and the derived quantity compliance at inspiratory capacity at inflation hold conditions can be regarded as a valid, accurate, and reliable surrogate measure for standard compliance of the respiratory system in contrast to ratio of tidal volume and ventilator pressure calculated from the ventilator readouts during ongoing mechanical ventilation at respective ventilator settings.

Long-term culture of bovine nucleus pulposus explants in a native environment.

PubMed

van Dijk, Bart G M; Potier, Esther; Ito, Keita

2013-04-01

Chronic low back pain is a disease with tremendous financial and social implications, and it is often caused by intervertebral disc degeneration. Regenerative therapies for disc repair are promising treatments, but they need to be tested in physiological models. To develop a physiological in vitro explant model that incorporates the native environment of the intervertebral disc, for example, hypoxia, low glucose, and high tissue osmolarity. Bovine nucleus pulposus (NP) explants were cultured for 42 days in conditions mimicking the native physiological environment. Two different approaches were used to balance the swelling pressure of the NP: raised medium osmolarity or an artificial annulus. Bovine NP explants were either cultured in media with osmolarity balanced at isotonic and hypertonic levels compared with the native tissue or cultured inside a fiber jacket used as an artificial annulus. Oxygen and glucose levels were set at either standard (21% O2 and 4.5 g/L glucose) or physiological (5% O2 and 1 g/L glucose) levels. Samples were analyzed at Day 0, 3, and 42 for tissue composition (water, sulfated glycosaminoglycans, DNA, and hydroxyproline contents and fixed charge density), tissue histology, cell viability, and cellular behavior with messenger RNA (mRNA) expression. Both the hypertonic culture and the artificial annulus approach maintained the tissue matrix composition for 42 days. At Day 3, mRNA expressions of aggrecan, collagen Type I, and collagen Type II in both hypertonic and artificial annulus cultures were not different from Day 0; however, at Day 42, the artificial annulus preserved the mRNA expression closer to Day 0. Gene expressions of matrix metalloprotease 13, tissue inhibitor of matrix metalloprotease 1, and tissue inhibitor of matrix metalloprotease 2 were downregulated under physiological O2 and glucose levels, whereas the other parameters analyzed were not affected. Although the hypertonic culture and the artificial annulus approach are both promising models to test regenerative therapies, the artificial annulus was better able to maintain a cellular behavior closer to the native tissue in longer term cultures. Copyright © 2013 Elsevier Inc. All rights reserved.

FABRICATION OF TUBE TYPE FUEL ELEMENT FOR NUCLEAR REACTORS

DOEpatents

Loeb, E.; Nicklas, J.H.

1959-02-01

A method of fabricating a nuclear reactor fuel element is given. It consists essentially of fixing two tubes in concentric relationship with respect to one another to provide an annulus therebetween, filling the annulus with a fissionablematerial-containing powder, compacting the powder material within the annulus and closing the ends thereof. The powder material is further compacted by swaging the inner surface of the inner tube to increase its diameter while maintaining the original size of the outer tube. This process results in reduced fabrication costs of powdered fissionable material type fuel elements and a substantial reduction in the peak core temperatures while materially enhancing the heat removal characteristics.

Ventilation planning at Energy West's Deer Creek mine

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

Tonc, L.; Prosser, B.; Gamble, G.

2009-08-15

In 2004 ventilation planning was initiated to exploit a remote area of Deer Creek mine's reserve (near Huntington, Utah), the Mill Fork Area, located under a mountain. A push-pull ventilation system was selected. This article details the design process of the ventilation system upgrade, the procurement process for the new fans, and the new fan startup testing. 5 figs., 1 photo.

Mine fire experiments and simulation with MFIRE

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

Laage, L.W.; Yang, Hang

1995-12-31

A major concern of mine fires is the heat generated ventilation disturbances which can move products of combustion (POC) through unexpected passageways. Fire emergency planning requires simulation of the interaction of the fire and ventilation system to predict the state of the ventilation system and the subsequent distribution of temperatures and POC. Several computer models were developed by the U.S. Bureau of Mines (USBM) to perform this simulation. The most recent, MFIRE, simulates a mine`s ventilation system and its response to altered ventilation parameters such as the development of new mine workings or changes in ventilation control structures, external influencemore » such as varying outside temperatures, and internal influences such as fires. Extensive output allows quantitative analysis of the effects of the proposed alteration to die ventilation system. This paper describes recent USBM research to validate MFIRE`s calculation of temperature distribution in an airway due to a mine fire, as temperatures are the most significant source of ventilation disturbances. Fire tests were conducted at the Waldo Mine near Magdalena, NM. From these experiments, temperature profiles were developed as functions of time and distance from the fire and compared with simulations from MFIRE.« less

On the Use of Windcatchers in Schools: Climate Change, Occupancy Patterns, and Adaptation Strategies

PubMed Central

Mumovic, D.

2009-01-01

Advanced naturally ventilated systems based on integration of basic natural ventilation strategies such as cross-ventilation and stack effect have been considered to be a key element of sustainable design. In this respect, there is a pressing need to explore the potential of such systems to achieve the recommended occupant comfort targets throughout their lifetime without relying on mechanical means. This study focuses on use of a windcatcher system in typical classrooms which are usually characterized by high and intermittent internal heat gains. The aims of this paper are 3-fold. First, to describe a series of field measurements that investigated the ventilation rates, indoor air quality, and thermal comfort in a newly constructed school located at an urban site in London. Secondly, to investigate the effect of changing climate and occupancy patterns on thermal comfort in selected classrooms, while taking into account adaptive potential of this specific ventilation strategy. Thirdly, to assess performance of the ventilation system using the newly introduced performance-based ventilation standards for school buildings. The results suggest that satisfactory occupant comfort levels could be achieved until the 2050s by a combination of advanced ventilation control settings and informed occupant behavior. PMID:27110216

77 FR 58421 - Model Safety Evaluation for Plant-Specific Adoption of Technical Specifications Task Force...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-09-20

... Ventilation System Surveillance Requirements To Operate for 10 Hours per Month,'' Using the Consolidated Line... currently require operating the ventilation system for at least 10 continuous hours with the heaters... Technical Specifications (TSs) Task Force (TSTF) Traveler TSTF-522, Revision 0, ``Revise Ventilation System...

40 CFR 147.3107 - Mechanical integrity.

Code of Federal Regulations, 2011 CFR

2011-07-01

... Oklahoma Indian Tribes § 147.3107 Mechanical integrity. (a) Monitoring of annulus pressure conducted pursuant to § 146.8(b)(1) shall be preceded by an initial pressure test. A positive gauge pressure on the casing/tubing annulus (filled with liquid) shall be maintained continuously. The pressure shall be...

40 CFR 147.3107 - Mechanical integrity.

Code of Federal Regulations, 2013 CFR

2013-07-01

... Oklahoma Indian Tribes § 147.3107 Mechanical integrity. (a) Monitoring of annulus pressure conducted pursuant to § 146.8(b)(1) shall be preceded by an initial pressure test. A positive gauge pressure on the casing/tubing annulus (filled with liquid) shall be maintained continuously. The pressure shall be...

40 CFR 147.3107 - Mechanical integrity.

Code of Federal Regulations, 2014 CFR

2014-07-01

... Oklahoma Indian Tribes § 147.3107 Mechanical integrity. (a) Monitoring of annulus pressure conducted pursuant to § 146.8(b)(1) shall be preceded by an initial pressure test. A positive gauge pressure on the casing/tubing annulus (filled with liquid) shall be maintained continuously. The pressure shall be...

40 CFR 147.3107 - Mechanical integrity.

Code of Federal Regulations, 2012 CFR

2012-07-01

... Oklahoma Indian Tribes § 147.3107 Mechanical integrity. (a) Monitoring of annulus pressure conducted pursuant to § 146.8(b)(1) shall be preceded by an initial pressure test. A positive gauge pressure on the casing/tubing annulus (filled with liquid) shall be maintained continuously. The pressure shall be...

46 CFR 108.437 - Pipe sizes and discharge rates for enclosed ventilation systems for rotating electrical equipment.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 4 2011-10-01 2011-10-01 false Pipe sizes and discharge rates for enclosed ventilation... Systems Fixed Carbon Dioxide Fire Extinguishing Systems § 108.437 Pipe sizes and discharge rates for enclosed ventilation systems for rotating electrical equipment. (a) The minimum pipe size for the initial...

Aortic annulus and ascending aorta: comparison of preoperative and periooperative measurement in patients with aortic stenosis.

PubMed

Smíd, Michal; Ferda, Jirí; Baxa, Jan; Cech, Jakub; Hájek, Tomás; Kreuzberg, Boris; Rokyta, Richard

2010-04-01

Precise determination of the aortic annulus size constitutes an integral part of the preoperative evaluation prior to aortic valve replacement. It enables the estimation of the size of prosthesis to be implanted. Knowledge of the size of the ascending aorta is required in the preoperative analysis and monitoring of its dilation enables the precise timing of the operation. Our goal was to compare the precision of measurement of the aortic annulus and ascending aorta using magnetic resonance (MR), multidetector-row computed tomography (MDCT), transthoracic echocardiography (TTE), and transoesophageal echocardiography (TEE) in patients with degenerative aortic stenosis. A total of 15 patients scheduled to have aortic valve replacement were enrolled into this prospective study. TTE was performed in all patients and was supplemented with TEE, CT and MR in the majority of patients. The values obtained were compared with perioperative measurements. For the measurement of aortic annulus, MR was found to be the most precise technique, followed by MDCT, TTE, and TEE. For the measurement of ascending aorta, MR again was found to be the most precise technique, followed by MDCT, TEE, and TTE. In our study, magnetic resonance was found to be the most precise technique for the measurement of aortic annulus and ascending aorta in patients with severe degenerative aortic stenosis. Copyright (c) 2010 Elsevier Ireland Ltd. All rights reserved.

The Effects of Physiological Biomechanical Loading on Intradiscal Pressure and Annulus Stress in Lumbar Spine: A Finite Element Analysis

PubMed Central

Zahari, Siti Nurfaezah; Rahim, Nor Raihanah Abdull; Kamarul, Tunku

2017-01-01

The present study was conducted to examine the effects of body weight on intradiscal pressure (IDP) and annulus stress of intervertebral discs at lumbar spine. Three-dimensional finite element model of osseoligamentous lumbar spine was developed subjected to follower load of 500 N, 800 N, and 1200 N which represent the loads for individuals who are normal and overweight with the pure moments at 7.5 Nm in flexion and extension motions. It was observed that the maximum IDP was 1.26 MPa at L1-L2 vertebral segment. However, the highest increment of IDP was found at L4-L5 segment where the IDP was increased to 30% in flexion and it was more severe at extension motion reaching to 80%. Furthermore, the maximum annulus stress also occurred at the L1-L2 segment with 3.9 MPa in extension motion. However, the highest increment was also found at L4-L5 where the annulus stress increased to 17% in extension motion. Based on these results, the increase of physiological loading could be an important factor to the increment of intradiscal pressure and annulus fibrosis stress at all intervertebral discs at the lumbar spine which may lead to early intervertebral disc damage. PMID:29065672

The Effects of Physiological Biomechanical Loading on Intradiscal Pressure and Annulus Stress in Lumbar Spine: A Finite Element Analysis.

PubMed

Zahari, Siti Nurfaezah; Latif, Mohd Juzaila Abd; Rahim, Nor Raihanah Abdull; Kadir, Mohammed Rafiq Abdul; Kamarul, Tunku

2017-01-01

The present study was conducted to examine the effects of body weight on intradiscal pressure (IDP) and annulus stress of intervertebral discs at lumbar spine. Three-dimensional finite element model of osseoligamentous lumbar spine was developed subjected to follower load of 500 N, 800 N, and 1200 N which represent the loads for individuals who are normal and overweight with the pure moments at 7.5 Nm in flexion and extension motions. It was observed that the maximum IDP was 1.26 MPa at L1-L2 vertebral segment. However, the highest increment of IDP was found at L4-L5 segment where the IDP was increased to 30% in flexion and it was more severe at extension motion reaching to 80%. Furthermore, the maximum annulus stress also occurred at the L1-L2 segment with 3.9 MPa in extension motion. However, the highest increment was also found at L4-L5 where the annulus stress increased to 17% in extension motion. Based on these results, the increase of physiological loading could be an important factor to the increment of intradiscal pressure and annulus fibrosis stress at all intervertebral discs at the lumbar spine which may lead to early intervertebral disc damage.

Numerical simulation and comparison of two ventilation methods for a restaurant - displacement vs mixed flow ventilation

NASA Astrophysics Data System (ADS)

Chitaru, George; Berville, Charles; Dogeanu, Angel

2018-02-01

This paper presents a comparison between a displacement ventilation method and a mixed flow ventilation method using computational fluid dynamics (CFD) approach. The paper analyses different aspects of the two systems, like the draft effect in certain areas, the air temperatureand velocity distribution in the occupied zone. The results highlighted that the displacement ventilation system presents an advantage for the current scenario, due to the increased buoyancy driven flows caused by the interior heat sources. For the displacement ventilation case the draft effect was less prone to appear in the occupied zone but the high heat emissions from the interior sources have increased the temperature gradient in the occupied zone. Both systems have been studied in similar conditions, concentrating only on the flow patterns for each case.

Short-term airing by natural ventilation - modeling and control strategies.

PubMed

Perino, M; Heiselberg, P

2009-10-01

The need to improve the energy efficiency of buildings requires new and more efficient ventilation systems. It has been demonstrated that innovative operating concepts that make use of natural ventilation seem to be more appreciated by occupants. This kind of system frequently integrates traditional mechanical ventilation components with natural ventilation devices, such as motorized windows and louvers. Among the various ventilation strategies that are currently available, buoyancy driven single-sided natural ventilation has proved to be very effective and can provide high air change rates for temperature and IAQ control. However, in order to promote a wider applications of these systems, an improvement in the knowledge of their working principles and the availability of new design and simulation tools is necessary. In this context, the paper analyses and presents the results of a research that was aimed at developing and validating numerical models for the analysis of buoyancy driven single-sided natural ventilation systems. Once validated, these models can be used to optimize control strategies in order to achieve satisfactory indoor comfort conditions and IAQ. Practical Implications Numerical and experimental analyses have proved that short-term airing by intermittent ventilation is an effective measure to satisfactorily control IAQ. Different control strategies have been investigated to optimize the capabilities of the systems. The proposed zonal model has provided good performances and could be adopted as a design tool, while CFD simulations can be profitably used for detailed studies of the pollutant concentration distribution in a room and to address local discomfort problems.

Inhibition of forkhead boxO-specific transcription prevents mechanical ventilation-induced diaphragm dysfunction.

PubMed

Smuder, Ashley J; Sollanek, Kurt J; Min, Kisuk; Nelson, W Bradley; Powers, Scott K

2015-05-01

Mechanical ventilation is a lifesaving measure for patients with respiratory failure. However, prolonged mechanical ventilation results in diaphragm weakness, which contributes to problems in weaning from the ventilator. Therefore, identifying the signaling pathways responsible for mechanical ventilation-induced diaphragm weakness is essential to developing effective countermeasures to combat this important problem. In this regard, the forkhead boxO family of transcription factors is activated in the diaphragm during mechanical ventilation, and forkhead boxO-specific transcription can lead to enhanced proteolysis and muscle protein breakdown. Currently, the role that forkhead boxO activation plays in the development of mechanical ventilation-induced diaphragm weakness remains unknown. This study tested the hypothesis that mechanical ventilation-induced increases in forkhead boxO signaling contribute to ventilator-induced diaphragm weakness. University research laboratory. Young adult female Sprague-Dawley rats. Cause and effect was determined by inhibiting the activation of forkhead boxO in the rat diaphragm through the use of a dominant-negative forkhead boxO adeno-associated virus vector delivered directly to the diaphragm. Our results demonstrate that prolonged (12 hr) mechanical ventilation results in a significant decrease in both diaphragm muscle fiber size and diaphragm-specific force production. However, mechanically ventilated animals treated with dominant-negative forkhead boxO showed a significant attenuation of both diaphragm atrophy and contractile dysfunction. In addition, inhibiting forkhead boxO transcription attenuated the mechanical ventilation-induced activation of the ubiquitin-proteasome system, the autophagy/lysosomal system, and caspase-3. Forkhead boxO is necessary for the activation of key proteolytic systems essential for mechanical ventilation-induced diaphragm atrophy and contractile dysfunction. Collectively, these results suggest that targeting forkhead boxO transcription could be a key therapeutic target to combat ventilator-induced diaphragm dysfunction.

Smart ventilation energy and indoor air quality performance in residential buildings: A review

DOE PAGES

Guyot, Gaelle; Sherman, Max H.; Walker, Iain S.

2017-12-30

To better address energy and indoor air quality issues, ventilation needs to become smarter. A key smart ventilation concept is to use controls to ventilate more at times it provides either an energy or indoor air quality (IAQ) advantage (or both) and less when it provides a disadvantage. A favorable context exists in many countries to include some of the existing smart ventilation strategies in codes and standards. As a result, demand-controlled ventilation (DCV) systems are widely and easily available on the market, with more than 20 DCV systems approved and available in countries such as Belgium, France and themore » Netherlands. This paper provides a literature review on smart ventilation used in residential buildings, based on energy and indoor air quality performance. This meta-analysis includes 38 studies of various smart ventilation systems with control based on CO 2, humidity, combined CO 2 and total volatile organic compounds (TVOC), occupancy, or outdoor temperature. In conclusion, these studies show that ventilation energy savings up to 60% can be obtained without compromising IAQ, even sometimes improving it. However, the meta-analysis included some less than favorable results, with 26% energy overconsumption in some cases.« less

Smart ventilation energy and indoor air quality performance in residential buildings: A review

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

Guyot, Gaelle; Sherman, Max H.; Walker, Iain S.

To better address energy and indoor air quality issues, ventilation needs to become smarter. A key smart ventilation concept is to use controls to ventilate more at times it provides either an energy or indoor air quality (IAQ) advantage (or both) and less when it provides a disadvantage. A favorable context exists in many countries to include some of the existing smart ventilation strategies in codes and standards. As a result, demand-controlled ventilation (DCV) systems are widely and easily available on the market, with more than 20 DCV systems approved and available in countries such as Belgium, France and themore » Netherlands. This paper provides a literature review on smart ventilation used in residential buildings, based on energy and indoor air quality performance. This meta-analysis includes 38 studies of various smart ventilation systems with control based on CO 2, humidity, combined CO 2 and total volatile organic compounds (TVOC), occupancy, or outdoor temperature. In conclusion, these studies show that ventilation energy savings up to 60% can be obtained without compromising IAQ, even sometimes improving it. However, the meta-analysis included some less than favorable results, with 26% energy overconsumption in some cases.« less

Outcomes management of mechanically ventilated patients: utilizing informatics technology.

PubMed

Smith, K R

1998-11-01

This article examines an informatics system developed for outcomes management of the mechanically ventilated adult population, focusing on weaning the patient from mechanical ventilation. The link between medical informatics and outcomes management is discussed, along with the development of methods, tools, and data sets for outcomes management of the mechanically ventilated adult population at an acute care academic institution. Pros and cons of this system are identified, and specific areas for improvement of future health care outcomes medical informatics systems are discussed.

B-Plant Canyon Ventilation Control System Description

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

MCDANIEL, K.S.

1999-08-31

Project W-059 installed a new B Plant Canyon Ventilation System. Monitoring and control of the system is implemented by the Canyon Ventilation Control System (CVCS). This document describes the CVCS system components which include a Programmable Logic Controller (PLC) coupled with an Operator Interface Unit (OIU) and application software. This document also includes an Alarm Index specifying the setpoints and technical basis for system analog and digital alarms.

[Cases and duration of mechanical ventilation in German hospitals : An analysis of DRG incentives and developments in respiratory medicine].

PubMed

Biermann, A; Geissler, A

2016-09-01

Diagnosis-related groups (DRGs) have been used to reimburse hospitals services in Germany since 2003/04. Like any other reimbursement system, DRGs offer specific incentives for hospitals that may lead to unintended consequences for patients. In the German context, specific procedures and their documentation are suspected to be primarily performed to increase hospital revenues. Mechanical ventilation of patients and particularly the duration of ventilation, which is an important variable for the DRG-classification, are often discussed to be among these procedures. The aim of this study was to examine incentives created by the German DRG-based payment system with regard to mechanical ventilation and to identify factors that explain the considerable increase of mechanically ventilated patients in recent years. Moreover, the assumption that hospitals perform mechanical ventilation in order to gain economic benefits was examined. In order to gain insights on the development of the number of mechanically ventilated patients, patient-level data provided by the German Federal Statistical Office and the German Institute for the Hospital Remuneration System were analyzed. The type of performed ventilation, the total number of ventilation hours, the age distribution, mortality and the DRG distribution for mechanical ventilation were calculated, using methods of descriptive and inferential statistics. Furthermore, changes in DRG-definitions and changes in respiratory medicine were compared for the years 2005-2012. Since the introduction of the DRG-based payment system in Germany, the hours of ventilation and the number of mechanically ventilated patients have substantially increased, while mortality has decreased. During the same period there has been a switch to less invasive ventilation methods. The age distribution has shifted to higher age-groups. A ventilation duration determined by DRG definitions could not be found. Due to advances in respiratory medicine, new ventilation methods have been introduced that are less prone to complications. This development has simultaneously improved survival rates. There was no evidence supporting the assumption that the duration of mechanical ventilation is influenced by the time intervals relevant for DRG grouping. However, presumably operational routines such as staff availability within early and late shifts of the hospital have a significant impact on the termination of mechanical ventilation.

HVEPS Scramjet-Driven MHD Power Demonstration Test Results (Preprint)

DTIC Science & Technology

2007-06-01

an outer annulus which provides the flow passage for the liquid NaK. Final fabrication and assembly of the seeding system was completed at UTRC as...ABSTRACT The Air Force sponsored Hypersonic Vehicle Electric Power System (HVEPS) program was a research program to develop scramjet driven...magnetohydrodynamic (MHD) power for an advanced high power, airborne electric power system . This program has been active for the past five years with various

Summarized Data of Test Space Heating, Ventilation and Air Conditioning Inspections from the Building Assessment Survey and Evaluation Study

EPA Pesticide Factsheets

Information on the characteristics of the heating, ventilation, and air conditioning (HVAC) system(s) in the entire BASE building including types of ventilation, equipment configurations, and operation and maintenance issues

Field evaluation of ventilation system performance in enclosed parking garages

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

Ayari, A.M.; Grot, D.A.; Krarti, M.

2000-07-01

This paper summarizes the results of a field study to determine the ventilation requirements and the contaminant levels in existing enclosed parking garages. The testing was conducted in seven parking garages with different sizes, traffic flow patterns, vehicle types, and locations. In particular, the study compares the actual ventilation rates measured using the tracer gas technique with the ventilation requirements of ANSI/ASHRAE Standard 62-1989. In addition, the field test evaluated the effectiveness of the existing ventilation systems in maintaining acceptable contaminant levels within enclosed parking garages.

Economic, Environmental and Health Implications of Enhanced Ventilation in Office Buildings.

PubMed

MacNaughton, Piers; Pegues, James; Satish, Usha; Santanam, Suresh; Spengler, John; Allen, Joseph

2015-11-18

Current building ventilation standards are based on acceptable minimums. Three decades of research demonstrates the human health benefits of increased ventilation above these minimums. Recent research also shows the benefits on human decision-making performance in office workers, which translates to increased productivity. However, adoption of enhanced ventilation strategies is lagging. We sought to evaluate two of the perceived potential barriers to more widespread adoption-Economic and environmental costs. We estimated the energy consumption and associated per building occupant costs for office buildings in seven U.S. cities, representing different climate zones for three ventilation scenarios (standard practice (20 cfm/person), 30% enhanced ventilation, and 40 cfm/person) and four different heating, ventilation and air conditioning (HVAC) system strategies (Variable Air Volume (VAV) with reheat and a Fan Coil Unit (FCU), both with and without an energy recovery ventilator). We also estimated emissions of greenhouse gases associated with this increased energy usage, and, for comparison, converted this to the equivalent number of vehicles using greenhouse gas equivalencies. Lastly, we paired results from our previous research on cognitive function and ventilation with labor statistics to estimate the economic benefit of increased productivity associated with increasing ventilation rates. Doubling the ventilation rate from the American Society of Heating, Refrigeration and Air-Conditioning Engineers minimum cost less than $40 per person per year in all climate zones investigated. Using an energy recovery ventilation system significantly reduced energy costs, and in some scenarios led to a net savings. At the highest ventilation rate, adding an ERV essentially neutralized the environmental impact of enhanced ventilation (0.03 additional cars on the road per building across all cities). The same change in ventilation improved the performance of workers by 8%, equivalent to a $6500 increase in employee productivity each year. Reduced absenteeism and improved health are also seen with enhanced ventilation. The health benefits associated with enhanced ventilation rates far exceed the per-person energy costs relative to salary costs. Environmental impacts can be mitigated at regional, building, and individual-level scales through the transition to renewable energy sources, adoption of energy efficient systems and ventilation strategies, and promotion of other sustainable policies.

Economic, Environmental and Health Implications of Enhanced Ventilation in Office Buildings

PubMed Central

MacNaughton, Piers; Pegues, James; Satish, Usha; Santanam, Suresh; Spengler, John; Allen, Joseph

2015-01-01

Introduction: Current building ventilation standards are based on acceptable minimums. Three decades of research demonstrates the human health benefits of increased ventilation above these minimums. Recent research also shows the benefits on human decision-making performance in office workers, which translates to increased productivity. However, adoption of enhanced ventilation strategies is lagging. We sought to evaluate two of the perceived potential barriers to more widespread adoption—Economic and environmental costs. Methods: We estimated the energy consumption and associated per building occupant costs for office buildings in seven U.S. cities, representing different climate zones for three ventilation scenarios (standard practice (20 cfm/person), 30% enhanced ventilation, and 40 cfm/person) and four different heating, ventilation and air conditioning (HVAC) system strategies (Variable Air Volume (VAV) with reheat and a Fan Coil Unit (FCU), both with and without an energy recovery ventilator). We also estimated emissions of greenhouse gases associated with this increased energy usage, and, for comparison, converted this to the equivalent number of vehicles using greenhouse gas equivalencies. Lastly, we paired results from our previous research on cognitive function and ventilation with labor statistics to estimate the economic benefit of increased productivity associated with increasing ventilation rates. Results: Doubling the ventilation rate from the American Society of Heating, Refrigeration and Air-Conditioning Engineers minimum cost less than $40 per person per year in all climate zones investigated. Using an energy recovery ventilation system significantly reduced energy costs, and in some scenarios led to a net savings. At the highest ventilation rate, adding an ERV essentially neutralized the environmental impact of enhanced ventilation (0.03 additional cars on the road per building across all cities). The same change in ventilation improved the performance of workers by 8%, equivalent to a $6500 increase in employee productivity each year. Reduced absenteeism and improved health are also seen with enhanced ventilation. Conclusions: The health benefits associated with enhanced ventilation rates far exceed the per-person energy costs relative to salary costs. Environmental impacts can be mitigated at regional, building, and individual-level scales through the transition to renewable energy sources, adoption of energy efficient systems and ventilation strategies, and promotion of other sustainable policies. PMID:26593933

Animal biocalorimeter and waste management system

NASA Technical Reports Server (NTRS)

Poppendiek, Heinz F. (Inventor); Trimailo, William R. (Inventor)

1995-01-01

A biocalorimeter and waste management system is provided for making metabolic heat release measurements of animals or humans in a calorimeter (enclosure) using ambient air as a low velocity source of ventilating air through the enclosure. A shroud forces ventilating air to pass over the enclosure from an end open to ambient air at the end of the enclosure opposite its ventilating air inlet end and closed around the inlet end of the enclosure in order to obviate the need for regulating ambient air temperature. Psychrometers for measuring dry- and wet-bulb temperature of ventilating air make it possible to account for the sensible and latent heat additions to the ventilating air. A waste removal system momentarily recirculates high velocity air in a closed circuit through the calorimeter wherein a sudden rise in moisture is detected in the ventilating air from the outlet.

Contaminants in ventilated filling boxes

NASA Astrophysics Data System (ADS)

Bolster, D. T.; Linden, P. F.

While energy efficiency is important, the adoption of energy-efficient ventilation systems still requires the provision of acceptable indoor air quality. Many low-energy systems, such as displacement or natural ventilation, rely on temperature stratification within the interior environment, always extracting the warmest air from the top of the room. Understanding buoyancy-driven convection in a confined ventilated space is key to understanding the flow that develops with many of these modern low-energy ventilation schemes. In this work we study the transport of an initially uniformly distributed passive contaminant in a displacement-ventilated space. Representing a heat source as an ideal sourced of buoyancy, analytical and numerical models are developed that allow us to compare the average efficiency of contaminant removal between traditional mixing and modern low-energy systems. A set of small-scale analogue laboratory experiments was also conducted to further validate our analytical and numerical solutions.We find that on average traditional and low-energy ventilation methods are similar with regard to pollutant flushing efficiency. This is because the concentration being extracted from the system at any given time is approximately the same for both systems. However, very different vertical concentration gradients exist. For the low-energy system, a peak in contaminant concentration occurs at the temperature interface that is established within the space. This interface is typically designed to sit at some intermediate height in the space. Since this peak does not coincide with the extraction point, displacement ventilation does not offer the same benefits for pollutant flushing as it does for buoyancy removal.

Characterizing a Co-Flow Nozzle for use in a Filtered Rayleigh Scattering System

DTIC Science & Technology

2006-06-01

61 Figure 31- Plot of centerline axial velocity and derivative along centerline of outer annulus while running... axial locations ................................................................................................. 64 Figure 34- Qualitative comparison...have axisymmetric annular flows centered on one another. These geometries are often found in combustors, turbofans , chemical processing and

Applied patent RFID systems for building reacting HEPA air ventilation system in hospital operation rooms.

PubMed

Lin, Jesun; Pai, Jar-Yuan; Chen, Chih-Cheng

2012-12-01

RFID technology, an automatic identification and data capture technology to provide identification, tracing, security and so on, was widely applied to healthcare industry in these years. Employing HEPA ventilation system in hospital is a way to ensure healthful indoor air quality to protect patients and healthcare workers against hospital-acquired infections. However, the system consumes lots of electricity which cost a lot. This study aims to apply the RFID technology to offer a unique medical staff and patient identification, and reacting HEPA air ventilation system in order to reduce the cost, save energy and prevent the prevalence of hospital-acquired infection. The system, reacting HEPA air ventilation system, contains RFID tags (for medical staffs and patients), sensor, and reacting system which receives the information regarding the number of medical staff and the status of the surgery, and controls the air volume of the HEPA air ventilation system accordingly. A pilot program was carried out in a unit of operation rooms of a medical center with 1,500 beds located in central Taiwan from Jan to Aug 2010. The results found the air ventilation system was able to function much more efficiently with less energy consumed. Furthermore, the indoor air quality could still keep qualified and hospital-acquired infection or other occupational diseases could be prevented.

Space station ventilation study

NASA Technical Reports Server (NTRS)

Colombo, G. V.; Allen, G. E.

1972-01-01

A ventilation system design and selection method which is applicable to any manned vehicle were developed. The method was used to generate design options for the NASA 33-foot diameter space station, all of which meet the ventilation system design requirements. System characteristics such as weight, volume, and power were normalized to dollar costs for each option. Total system costs for the various options ranged from a worst case $8 million to a group of four which were all approximately $2 million. A system design was then chosen from the $2 million group and is presented in detail. A ventilation system layout was designed for the MSFC space station mockup which provided comfortable, efficient ventilation of the mockup. A conditioned air distribution system design for the 14-foot diameter modular space station, using the same techniques, is also presented. The tradeoff study resulted in the selection of a system which costs $1.9 million, as compared to the alternate configuration which would have cost $2.6 million.

Liquid-metal dip seal with pneumatic spring

DOEpatents

Poindexter, Allan M.

1977-01-01

An improved liquid-metal dip seal for sealing the annulus between rotating plugs in the reactor vessel head of a liquid-metal fast-breeder nuclear reactor has two legs of differing widths communicating under a seal blade; the wide leg is also in communication with cover gas of the reactor and the narrow leg is also in communication with an isolated plug annulus above the seal. The annulus contains inert gas which acts as a pneumatic spring. Upon increasing cover gas pressure which depresses the level in the wide leg and greatly increases the level in the narrow leg, the pneumatic spring is compressed, and resists further level changes, thus preventing radioactive cover gas from bubbling through the seal.

Mild hypothermia attenuates changes in respiratory system mechanics and modifies cytokine concentration in bronchoalveolar lavage fluid during low lung volume ventilation.

PubMed

Dostál, P; Senkeřík, M; Pařízková, R; Bareš, D; Zivný, P; Zivná, H; Cerný, V

2010-01-01

Hypothermia was shown to attenuate ventilator-induced lung injury due to large tidal volumes. It is unclear if the protective effect of hypothermia is maintained under less injurious mechanical ventilation in animals without previous lung injury. Tracheostomized rats were randomly allocated to non-ventilated group (group C) or ventilated groups of normothermia (group N) and mild hypothermia (group H). After two hours of mechanical ventilation with inspiratory fraction of oxygen 1.0, respiratory rate 60 min(-1), tidal volume 10 ml x kg(-1), positive end-expiratory pressure (PEEP) 2 cm H2O or immediately after tracheostomy in non-ventilated animals inspiratory pressures were recorded, rats were sacrificed, pressure-volume (PV) curve of respiratory system constructed, bronchoalveolar lavage (BAL) fluid and aortic blood samples obtained. Group N animals exhibited a higher rise in peak inspiratory pressures in comparison to group H animals. Shift of the PV curve to right, higher total protein and interleukin-6 levels in BAL fluid were observed in normothermia animals in comparison with hypothermia animals and non-ventilated controls. Tumor necrosis factor-alpha was lower in the hypothermia group in comparison with normothermia and non-ventilated groups. Mild hypothermia attenuated changes in respiratory system mechanics and modified cytokine concentration in bronchoalveolar lavage fluid during low lung volume ventilation in animals without previous lung injury.

The Development of a Gas–Liquid Two-Phase Flow Sensor Applicable to CBM Wellbore Annulus

PubMed Central

Wu, Chuan; Wen, Guojun; Han, Lei; Wu, Xiaoming

2016-01-01

The measurement of wellbore annulus gas–liquid two-phase flow in CBM (coalbed methane) wells is of great significance for reasonably developing gas drainage and extraction processes, estimating CBM output, judging the operating conditions of CBM wells and analyzing stratum conditions. Hence, a specially designed sensor is urgently needed for real-time measurement of gas–liquid two-phase flow in CBM wellbore annulus. Existing flow sensors fail to meet the requirements of the operating conditions of CBM wellbore annulus due to such factors as an inapplicable measurement principle, larger size, poor sealability, high installation accuracy, and higher requirements for fluid media. Therefore, based on the principle of a target flowmeter, this paper designs a new two-phase flow sensor that can identify and automatically calibrate different flow patterns of two-phase flows. Upon the successful development of the new flow sensor, lab and field tests were carried out, and the results show that the newly designed sensor, with a measurement accuracy of ±2.5%, can adapt to the operating conditions of CBM wells and is reliable for long-term work. PMID:27869708

The Development of a Gas-Liquid Two-Phase Flow Sensor Applicable to CBM Wellbore Annulus.

PubMed

Wu, Chuan; Wen, Guojun; Han, Lei; Wu, Xiaoming

2016-11-18

The measurement of wellbore annulus gas-liquid two-phase flow in CBM (coalbed methane) wells is of great significance for reasonably developing gas drainage and extraction processes, estimating CBM output, judging the operating conditions of CBM wells and analyzing stratum conditions. Hence, a specially designed sensor is urgently needed for real-time measurement of gas-liquid two-phase flow in CBM wellbore annulus. Existing flow sensors fail to meet the requirements of the operating conditions of CBM wellbore annulus due to such factors as an inapplicable measurement principle, larger size, poor sealability, high installation accuracy, and higher requirements for fluid media. Therefore, based on the principle of a target flowmeter, this paper designs a new two-phase flow sensor that can identify and automatically calibrate different flow patterns of two-phase flows. Upon the successful development of the new flow sensor, lab and field tests were carried out, and the results show that the newly designed sensor, with a measurement accuracy of ±2.5%, can adapt to the operating conditions of CBM wells and is reliable for long-term work.

Demand controlled ventilating systems: Sensor market survey. Energy conservation in buildings and community systems programme, annex 18, December 1991

NASA Astrophysics Data System (ADS)

Raatschen, W.; Sjoegren, M.

The subject of indoor and outdoor air quality has generated a great deal of attention in many countries. Areas of concern include outgassing of building materials as well as occupant-generated pollutants such as carbon dioxide, moisture, and odors. Progress has also been made towards addressing issues relating to the air tightness of the building envelope. Indoor air quality studies indicate that better control of supply flow rates as well as the air distribution pattern within buildings are necessary. One method of maintaining good indoor air quality without extensive energy consumption is to control the ventilation rate according to the needs and demands of the occupants, or to preserve the building envelope. This is accomplished through the use of demand controlled ventilating (DCV) systems. The specific objective of Annex 18 is to develop guidelines for demand controlled ventilating systems based on state of the art analyses, case studies on ventilation effectiveness, and proposed ventilation rates for different users in domestic, office, and school buildings.

Equation Discovery for Model Identification in Respiratory Mechanics of the Mechanically Ventilated Human Lung

NASA Astrophysics Data System (ADS)

Ganzert, Steven; Guttmann, Josef; Steinmann, Daniel; Kramer, Stefan

Lung protective ventilation strategies reduce the risk of ventilator associated lung injury. To develop such strategies, knowledge about mechanical properties of the mechanically ventilated human lung is essential. This study was designed to develop an equation discovery system to identify mathematical models of the respiratory system in time-series data obtained from mechanically ventilated patients. Two techniques were combined: (i) the usage of declarative bias to reduce search space complexity and inherently providing the processing of background knowledge. (ii) A newly developed heuristic for traversing the hypothesis space with a greedy, randomized strategy analogical to the GSAT algorithm. In 96.8% of all runs the applied equation discovery system was capable to detect the well-established equation of motion model of the respiratory system in the provided data. We see the potential of this semi-automatic approach to detect more complex mathematical descriptions of the respiratory system from respiratory data.

Annular inhomogeneities with eigenstrain and interphase modeling

NASA Astrophysics Data System (ADS)

Markenscoff, Xanthippi; Dundurs, John

2014-03-01

Two and three-dimensional analytical solutions for an inhomogeneity annulus/ring (of arbitrary thickness) with eigenstrain are presented. The stresses in the core may become tensile (for dilatational eigenstrain in the annulus) depending on the relative shear moduli. For shear eigenstrain, an “interface rotation” and rotation jumps at the interphase also occur, consistent with the Frank-Bilby interface model. A Taylor series expansion for small thickness of the annulus is obtained to the second-order as to model thin interphases, with the limit agreeing with the Gurtin-Murdoch surface membrane, but also accounting for curvature effects.. The Eshelby “driving forces” on a boundary with eigenstrain are calculated, and for small, but finite, interphase thicknesses they account for the interaction of the two interfaces of the layer, and the next order term may induce instabilities, for some bimaterial combinations, if it becomes large enough to render the driving force zero. It is also proven that for 2-D inhomogeneities with eigenstrain the stresses have reduced material dependence for any geometry of the inhomogeneity. The case when the outer boundary of the inhomogeneity annulus with eigenstrain is a free surface is also analyzed and agrees with classical surface tension results in the limit, but, moreover, the thick free surface terms (next order in the expansion depending on the radius) are also obtained and may induce instabilities depending on the bimaterial combinations. Applications of inhomogeneity annuluses with eigenstrain are wide and include interphases in thermal barrier coatings and coated particles in electrically/thermally conductive adhesives.

Aortic annulus sizing using watershed transform and morphological approach for CT images

NASA Astrophysics Data System (ADS)

Mohammad, Norhasmira; Omar, Zaid; Sahrim, Mus'ab

2018-02-01

Aortic valve disease occurs due to calcification deposits on the area of leaflets within the human heart. It is progressive over time where it can affect the mechanism of the heart valve. To avoid the risk of surgery for vulnerable patients especially senior citizens, a new method has been introduced: Transcatheter Aortic Valve Implantation (TAVI), which places a synthetic catheter within the patient's valve. This entails a procedure of aortic annulus sizing, which requires manual measurement of the scanned images acquired from Computed Tomographic (CT) by experts. The step requires intensive efforts, though human error may still eventually lead to false measurement. In this research, image processing techniques are implemented onto cardiac CT images to achieve an automated and accurate measurement of the heart annulus. The image is first put through pre-processing for noise filtration and image enhancement. Then, a marker image is computed using the combination of opening and closing operations where the foreground image is marked as a feature while the background image is set to zero. Marker image is used to control the watershed transformation and also to prevent oversegmentation. This transformation has the advantage of fast computational and oversegmentation problems, which usually appear with the watershed transform can be solved with the introduction of marker image. Finally, the measurement of aortic annulus from the image data is obtained through morphological operations. Results affirm the approach's ability to achieve accurate annulus measurements compared to conventional techniques.

The geometrical effect of different annuloplasty rings on mitral valve annulus.

PubMed

Al-Maisary, Sameer; Graser, Bastian; Engelhardt, Sandy; Wolf, Ivo; Karck, Matthias; DE Simone, Raffaele

2017-06-01

Different types of mitral annuloplasty rings are commercially available. The aim of this study was to investigate the effect of implantation of six types of annuloplasty rings on the geometry and dynamics of the mitral valve. Three-dimensional echocardiography images of 42 patients were acquired to visualize the mitral valve annulus. Virtual representations of six commercially available annuloplasty rings were matched to anatomical mitral annuli of each patient according to anterolateral-posteromedial diameter. The virtual displacement of each annuloplasty ring after the implantation was measured and compared with the other rings. Patients with severe mitral regurgitation had significantly dilated annuli according to anterolateral-posteromedial diameter, anterior-posterior diameter and to annulus circumference. Anterior and posterior heights of the mitral annuli and non-planarity angle showed no significant differences among different patients with different degree of mitral regurgitation. The ratio of anterior-posterior to anterolateral-posteromedial diameter was almost identical in all groups with identical annular shapes. The implantation of the Carpentier-Edwards Classic Annuloplasty Ring™ led to maximal displacement of mitral annulus, followed by the IM-Ring™, without a statistical significance. In contrary, the implantation of a MyxoETlogix Ring™ was associated with minimal displacement of mitral annulus throughout the groups, but without statistical significance. The implantation of different ring types in patients with different annuli shapes and dimensions did not lead to any significant change in the configuration of mitral annuli after the virtual implantation of the tested annuloplasty rings.

46 CFR 194.20-5 - Ventilation.

Code of Federal Regulations, 2010 CFR

2010-10-01

... GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OCEANOGRAPHIC RESEARCH VESSELS HANDLING, USE, AND... Ventilation. (a) Chemical storerooms shall be equipped with a power ventilation system of exhaust type. The... based upon the volume of the compartment. (1) Power ventilation units shall have nonsparking impellers...

Protective garment ventilation system

NASA Technical Reports Server (NTRS)

Lang, R. (Inventor)

1970-01-01

A method and apparatus for ventilating a protective garment, space suit system, and/or pressure suits to maintain a comfortable and nontoxic atmosphere within is described. The direction of flow of a ventilating and purging gas in portions of the garment may be reversed in order to compensate for changes in environment and activity of the wearer. The entire flow of the ventilating gas can also be directed first to the helmet associated with the garment.

Carbon Dioxide Detection and Indoor Air Quality Control.

PubMed

Bonino, Steve

2016-04-01

When building ventilation is reduced, energy is saved because it is not necessary to heat or cool as much outside air. Reduced ventilation can result in higher levels of carbon dioxide, which may cause building occupants to experience symptoms. Heating or cooling for ventilation air can be enhanced by a DCV system, which can save energy while providing a comfortable environment. Carbon dioxide concentrations within a building are often used to indicate whether adequate fresh air is being supplied to the building. These DCV systems use carbon dioxide sensors in each space or in the return air and adjust the ventilation based on carbon dioxide concentration; the higher the concentration, the more people occupy the space relative to the ventilation rate. With a carbon dioxide sensor DCV system, the fresh air ventilation rate varies based on the number ofpeople in the space, saving energy while maintaining a safe and comfortable environment.

Atrial and ventricular function after cardioversion of atrial fibrillation.

PubMed Central

Xiong, C.; Sonnhag, C.; Nylander, E.; Wranne, B.

1995-01-01

OBJECTIVE--Previous studies on atrial recovery after cardioversion of atrial fibrillation have not taken into account new knowledge about the pathophysiology of transmitral and transtricuspid flow velocity patterns. It is possible to shed further light on this problem if atrioventricular inflow velocity, venous filling pattern, and atrioventricular annulus motion are recorded and interpreted together. DESIGN--Prospective examinations of mitral and tricuspid transvalvar flow velocities, superior caval and pulmonary venous filling, and mitral and tricuspid annulus motion were recorded using Doppler echocardiography. Examinations were performed before and 24 hours, 1 month, and 20 months after cardioversion. SETTING--Tertiary referral centre for cardiac disease with facilities for invasive and non-invasive investigation. PATIENTS--16 patients undergoing cardioversion of atrial fibrillation in whom sinus rhythm had persisted for 24 hours or more. RESULTS--Before conversion there was no identifiable A wave in transvalvar flow recordings. The total motion of the tricuspid and mitral annulus was subnormal and there was no identifiable atrial component. Venous flow patterns in general showed a low systolic velocity. After conversion, A waves and atrial components were seen in all patients and increased significantly (P < 0.01) with time. There was a similar time course for the amplitude of annulus atrial components, an increased systolic component of venous inflow, an increased A wave velocity, and a decreased E/A ratio of the transvalvar velocity curves. The ventricular component of annulus motion was unchanged. Changes in general occurred earlier on the right side than the left. CONCLUSIONS--This study indicates that, in addition to the previously known electromechanical dissociation of atrial recovery that exists after cardioversion of atrial fibrillation, there may also be a transient deterioration of ventricular function modulating the transvalvar inflow velocity recordings. Function on the right side generally becomes normal earlier than on the left. Integration of information from transvalvar inflow curves, annulus motion, and venous filling patterns gives additional insight into cardiac function. PMID:7547019

Implantation of personalized, biocompatible mitral annuloplasty rings: feasibility study in an animal model

PubMed Central

Sündermann, Simon H.; Gessat, Michael; Cesarovic, Nikola; Frauenfelder, Thomas; Biaggi, Patric; Bettex, Dominique; Falk, Volkmar; Jacobs, Stephan

2013-01-01

OBJECTIVES Implantation of an annuloplasty ring is an essential component of a durable mitral valve repair. Currently available off-the-shelf rings still do not cover all the variations in mitral annulus anatomy and pathology from subject to subject. Computed tomography (CT) and echo imaging allow for 3-D segmentation of the mitral valve and mitral annulus. The concept of tailored annuloplasty rings has been proposed although, to date, no surgically applicable implementation of patient-specific annuloplasty rings has been seen. The objective of this trial was to prove the concept of surgical implantation of a model-guided, personalized mitral annuloplasty ring, manufactured based on individual CT-scan models. METHODS ECG-gated CT angiography was performed in six healthy pigs under general anaesthesia. Based on the individual shape of the mitral annulus in systole, a customized solid ring with integrated suturing holes was designed and manufactured from a biocompatible titanium alloy by a rapid process using laser melting. The ring was implanted three days later and valve function was assessed by intraoperative echocardiography. The macroscopic annulus–annuloplasty match was assessed after heart explantation. RESULTS CT angiography provided good enough image quality in all animals to allow for segmentation of the mitral annulus. The individually tailored mitral rings were manufactured and successfully implanted in all pigs. In 50%, a perfect matching of the implanted ring and the mitral annulus was achieved. In one animal, a slight deviation of the ring shape from the circumference was seen postoperatively. The rings implanted in the first two animals were significantly oversized but the deviation did not affect valve competence. CONCLUSIONS CT image quality and accuracy of the dimensions of the mitral annulus were sufficient for digital modelling and rapid manufacturing of mitral rings. Implantation of individually tailored annuloplasty rings is feasible. PMID:23287589

A new system for continuous and remote monitoring of patients receiving home mechanical ventilation

NASA Astrophysics Data System (ADS)

Battista, L.

2016-09-01

Home mechanical ventilation is the treatment of patients with respiratory failure or insufficiency by means of a mechanical ventilator at a patient's home. In order to allow remote patient monitoring, several tele-monitoring systems have been introduced in the last few years. However, most of them usually do not allow real-time services, as they have their own proprietary communication protocol implemented and some ventilation parameters are not always measured. Moreover, they monitor only some breaths during the whole day, despite the fact that a patient's respiratory state may change continuously during the day. In order to reduce the above drawbacks, this work reports the development of a novel remote monitoring system for long-term, home-based ventilation therapy; the proposed system allows for continuous monitoring of the main physical quantities involved during home-care ventilation (e.g., differential pressure, volume, and air flow rate) and is developed in order to allow observations of different remote therapy units located in different places of a city, region, or country. The developed remote patient monitoring system is able to detect various clinical events (e.g., events of tube disconnection and sleep apnea events) and has been successfully tested by means of experimental tests carried out with pulmonary ventilators typically used to support sick patients.

A new system for continuous and remote monitoring of patients receiving home mechanical ventilation.

PubMed

Battista, L

2016-09-01

Home mechanical ventilation is the treatment of patients with respiratory failure or insufficiency by means of a mechanical ventilator at a patient's home. In order to allow remote patient monitoring, several tele-monitoring systems have been introduced in the last few years. However, most of them usually do not allow real-time services, as they have their own proprietary communication protocol implemented and some ventilation parameters are not always measured. Moreover, they monitor only some breaths during the whole day, despite the fact that a patient's respiratory state may change continuously during the day. In order to reduce the above drawbacks, this work reports the development of a novel remote monitoring system for long-term, home-based ventilation therapy; the proposed system allows for continuous monitoring of the main physical quantities involved during home-care ventilation (e.g., differential pressure, volume, and air flow rate) and is developed in order to allow observations of different remote therapy units located in different places of a city, region, or country. The developed remote patient monitoring system is able to detect various clinical events (e.g., events of tube disconnection and sleep apnea events) and has been successfully tested by means of experimental tests carried out with pulmonary ventilators typically used to support sick patients.

Aortic annulus and root characteristics in severe aortic stenosis due to bicuspid aortic valve and tricuspid aortic valves: implications for transcatheter aortic valve therapies.

PubMed

Philip, Femi; Faza, Nadine Nadar; Schoenhagen, Paul; Desai, Milind Y; Tuzcu, E Murat; Svensson, Lars G; Kapadia, Samir R

2015-08-01

Patients with severe aortic stenosis due to BAV are excluded from transcatheter aortic valve replacement (TAVR) due to concern for asymmetric expansion and valve dysfunction. We sought to characterize the aortic root and annulus in bicuspid aortic valve (BAV) and tricuspid aortic valves (TAV). We identified patients with severe AS who underwent multi-detector computed tomographic (MDCT) imaging prior to surgical aortic valve replacement (SAVR, n = 200) for BAV and TAVR (n = 200) for TAV from 2010 to 2013. The presence of a BAV was confirmed on surgical and pathological review. Annulus measurements of the basal ring (short- and long-axis, area-derived diameter), coronary ostia height, sinus area (SA), sino-tubular junction area (STJ), calcification and eccentricity index (EI, 1-short axis/long axis) were made. Patients with TAV were older (78.8 years vs. 57.8 years, P = 0.04) than those with BAV. The aortic annulus area (5.21 ± 2.1 cm(2) vs. 4.63 ± 2.0 cm(2) , P = 0.0001), sinus of Valsalva diameter (3.7 ± 0.9 cm vs. 3.1 ± 0.1 cm, P = 0.001) and ascending aorta diameter (3.5 ± 0.7 cm vs. 2.97 ± 0.6 cm, P = 0.001) were significantly larger with BAV. Bicuspid aortic annuli were significantly less elliptical (EI, 1.24 ± 0.1 vs. 1.29 ± 0.1, P = 0.006) and more circular (39% vs. 4%, P < 0.001) compared to the TAV annulus. There was more eccentric annular calcification in BAV vs. TAV (68% vs. 32%, P < 0.001). The mean distance from the aortic annulus to the left main coronary ostium was less than the right coronary ostium. Less than 10% of the BAV annuli would not fit a currently available valved stents. Bicuspid aortic valves have a larger annulus size, sinus of Valsalva and ascending aorta dimensions. In addition, the BAV aortic annuli appear circular and most will fit currently available commercial valved stents. © 2015 Wiley Periodicals, Inc.

Lamellar and fibre bundle mechanics of the annulus fibrosus in bovine intervertebral disc.

PubMed

Vergari, Claudio; Mansfield, Jessica; Meakin, Judith R; Winlove, Peter C

2016-06-01

The intervertebral disc is a multicomposite structure, with an outer fibrous ring, the annulus fibrosus, retaining a gel-like core, the nucleus pulposus. The disc presents complex mechanical behaviour, and it is of high importance for spine biomechanics. Advances in multiscale modelling and disc repair raised a need for new quantitative data on the finest details of annulus fibrosus mechanics. In this work we explored inter-lamella and inter-bundle behaviour of the outer annulus using micromechanical testing and second harmonic generation microscopy. Twenty-one intervertebral discs were dissected from cow tails; the nucleus and inner annulus were excised to leave a ring of outer annulus, which was tested in circumferential loading while imaging the tissue's collagen fibres network with sub-micron resolution. Custom software was developed to determine local tissue strains through image analysis. Inter-bundle linear and shear strains were 5.5 and 2.8 times higher than intra-bundle strains. Bundles tended to remain parallel while rotating under loading, with large slipping between them. Inter-lamella linear strain was almost 3 times the intra-lamella one, but no slipping was observed at the junction between lamellae. This study confirms that outer annulus straining is mainly due to bundles slipping and rotating. Further development of disc multiscale modelling and repair techniques should take into account this modular behaviour of the lamella, rather than considering it as a homogeneous fibre-reinforced matrix. The intervertebral disc is an organ tucked between each couple of vertebrae in the spine. It is composed by an outer fibrous layer retaining a gel-like core. This organ undergoes severe and repeated loading during everyday life activities, since it is the compliant component that gives the spine its flexibility. Its properties are affected by pathologies such as disc degeneration, a major cause of back pain. In this article we explored the micromechanical behaviour of the disc's outer layer using second harmonic generation, a technique which allowed us to visualize, with unprecedented detail, how bundles of collagen fibres slide relative to each other when loaded. Our results will help further the development of new multiscale numerical models and repairing techniques. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Posterior convex release and interbody fusion for thoracic scoliosis: technical note.

PubMed

Mac-Thiong, Jean-Marc; Asghar, Jahangir; Parent, Stefan; Shufflebarger, Harry L; Samdani, Amer; Labelle, Hubert

2016-09-01

Anterior release and fusion is sometimes required in pediatric patients with thoracic scoliosis. Typically, a formal anterior approach is performed through open thoracotomy or video-assisted thoracoscopic surgery. The authors recently developed a technique for anterior release and fusion in thoracic scoliosis referred to as "posterior convex release and interbody fusion" (PCRIF). This technique is performed via the posterior-only approach typically used for posterior instrumentation and fusion and thus avoids a formal anterior approach. In this article the authors describe the technique and its use in 9 patients-to prevent a crankshaft phenomenon in 3 patients and to optimize the correction in 6 patients with a severe thoracic curve showing poor reducibility. After Ponte osteotomies at the levels requiring anterior release and fusion, intervertebral discs are approached from the convex side of the scoliosis. The annulus on the convex side of the scoliosis is incised from the lateral border of the pedicle to the lateral annulus while visualizing and protecting the pleura and spinal cord. The annulus in contact with the pleura and the anterior longitudinal ligament are removed before completing the discectomies and preparing the endplates. The PCRIF was performed at 3 levels in 4 patients and at 4 levels in 5 patients. Mean correction of the main thoracic curve, blood loss, and length of stay were 74.9%, 1290 ml, and 7.6 days, respectively. No neurological deficit, implant failure, or pseudarthrosis was observed at the last follow-up. Two patients had pleural effusion postoperatively, with 1 of them requiring placement of a chest tube. One patient had pulmonary edema secondary to fluid overload, while another patient underwent reoperation for a deep wound infection 3 weeks after the initial surgery. The technique is primarily indicated in skeletally immature patients with open triradiate cartilage and/or severe scoliosis. It can be particularly useful if there is significant vertebral rotation because access to the disc and anterior longitudinal ligament from the convex side will become safer. The PCRIF is an alternative to the formal anterior approach and does not require repositioning between the anterior and posterior stages, which prolongs the surgery and can be associated with an increased complication rate. The procedure can be done in the presence of preexisting pulmonary morbidity such as pleural adhesions and decreased pulmonary function because it does not require mobilization of the lung or single-lung ventilation. However, PCRIF can still be associated with pulmonary complications such as a pleural effusion, and care should be taken to avoid iatrogenic injury to the pleura. Placement of a deep wound drain at the level of the PCRIF is strongly recommended if postoperative bleeding is anticipated, to decrease the risk of pleural effusion.

Tank Remote Repair System Conceptual Design

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

Kriikku, E.

2002-12-06

This document describes two conceptual designs for a Tank Remote Repair System to perform leak site repairs of double shell waste tank walls (Types I, II, III, and IIIA) from the annulus space. The first concept uses a magnetic wall crawler and an epoxy patch system and the second concept uses a magnetic wall crawler and a magnetic patch system. The recommended concept uses the magnetic patch system, since it is simpler to deliver, easier to apply, and has a higher probability of stopping an active leak.

Comfort parameters - Ventilation of a subway wagon

NASA Astrophysics Data System (ADS)

Petr, Pavlíček; Ladislav, Tříska

2017-09-01

Research and development of a ventilation system is being carried out as a part of project TA04030774 of the Technology Agency of the Czech Republic. Name of the project is "Research and Development of Mass-optimized Components for Rail Vehicles". Problems being solved are development and testing of a new concept for ventilation systems for public transport vehicles. The main improvements should be a reduction of the mass of the whole system, easy installation and reduction of the noise of the ventilation system. This article is focused on the comfort parameters in a subway wagon (measurement and evaluation carried out on a function sample in accordance with the regulations). The input to the project is a ventilator hybrid casing for a subway wagon, which was manufactured and tested during the Ministry of Industry and Trade project TIP FR-TI3/449.

40 CFR 98.323 - Calculating GHG emissions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... systems (metric tons CH4). CH4V = Quarterly CH4 liberated from each ventilation monitoring point (metric... vent holes are collected, you must calculate the quarterly CH4 liberated from the ventilation system... CH4 liberated from a ventilation monitoring point (metric tons CH4). V = Volumetric flow rate for the...

24 CFR 3280.710 - Venting, ventilation and combustion air.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 24 Housing and Urban Development 5 2010-04-01 2010-04-01 false Venting, ventilation and combustion... Fuel Burning Systems § 3280.710 Venting, ventilation and combustion air. (a) The venting as required by... appliance listing and the appliance manufacturer's instructions. (b) Venting and combustion air systems...

24 CFR 3280.710 - Venting, ventilation and combustion air.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 24 Housing and Urban Development 5 2014-04-01 2014-04-01 false Venting, ventilation and combustion... Fuel Burning Systems § 3280.710 Venting, ventilation and combustion air. (a) The venting as required by... appliance listing and the appliance manufacturer's instructions. (b) Venting and combustion air systems...

24 CFR 3280.710 - Venting, ventilation and combustion air.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 24 Housing and Urban Development 5 2012-04-01 2012-04-01 false Venting, ventilation and combustion... Fuel Burning Systems § 3280.710 Venting, ventilation and combustion air. (a) The venting as required by... appliance listing and the appliance manufacturer's instructions. (b) Venting and combustion air systems...

24 CFR 3280.710 - Venting, ventilation and combustion air.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 24 Housing and Urban Development 5 2011-04-01 2011-04-01 false Venting, ventilation and combustion... Fuel Burning Systems § 3280.710 Venting, ventilation and combustion air. (a) The venting as required by... appliance listing and the appliance manufacturer's instructions. (b) Venting and combustion air systems...

24 CFR 3280.710 - Venting, ventilation and combustion air.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 24 Housing and Urban Development 5 2013-04-01 2013-04-01 false Venting, ventilation and combustion... Fuel Burning Systems § 3280.710 Venting, ventilation and combustion air. (a) The venting as required by... appliance listing and the appliance manufacturer's instructions. (b) Venting and combustion air systems...

CFD Modeling of Swirl and Nonswirl Gas Injections into Liquid Baths Using Top Submerged Lances

NASA Astrophysics Data System (ADS)

Huda, Nazmul; Naser, J.; Brooks, G.; Reuter, M. A.; Matusewicz, R. W.

2010-02-01

Fluid flow phenomena in a cylindrical bath stirred by a top submerged lance (TSL) gas injection was investigated by using the computational fluid dynamic (CFD) modeling technique for an isothermal air-water system. The multiphase flow simulation, based on the Euler-Euler approach, elucidated the effect of swirl and nonswirl flow inside the bath. The effects of the lance submergence level and the air flow rate also were investigated. The simulation results for the velocity fields and the generation of turbulence in the bath were validated against existing experimental data from the previous water model experimental study by Morsi et al.[1] The model was extended to measure the degree of the splash generation for different liquid densities at certain heights above the free surface. The simulation results showed that the two-thirds lance submergence level provided better mixing and high liquid velocities for the generation of turbulence inside the water bath. However, it is also responsible for generating more splashes in the bath compared with the one-third lance submergence level. An approach generally used by heating, ventilation, and air conditioning (HVAC) system simulations was applied to predict the convective mixing phenomena. The simulation results for the air-water system showed that mean convective mixing for swirl flow is more than twice than that of nonswirl in close proximity to the lance. A semiempirical equation was proposed from the results of the present simulation to measure the vertical penetration distance of the air jet injected through the annulus of the lance in the cylindrical vessel of the model, which can be expressed as L_{va} = 0.275( {do - di } )Frm^{0.4745} . More work still needs to be done to predict the detail process kinetics in a real furnace by considering nonisothermal high-temperature systems with chemical reactions.

30 CFR 250.522 - When do I have to repeat casing diagnostic testing?

Code of Federal Regulations, 2011 CFR

2011-07-01

... term has expired, immediately. (b) your well, previously on gas lift, has been shut-in or returned to flowing status without gas lift for more than 180 days, immediately on the production casing (A annulus). The production casing (A annulus) of wells on active gas lift are exempt from diagnostic testing. (c...

Apodizer aperture for lasers

DOEpatents

Jorna, Siebe; Siebert, Larry D.; Brueckner, Keith A.

1976-11-09

An aperture attenuator for use with high power lasers which includes glass windows shaped and assembled to form an annulus chamber which is filled with a dye solution. The annulus chamber is shaped such that the section in alignment with the axis of the incident beam follows a curve which is represented by the equation y = (r - r.sub.o).sup.n.

Bounding the number of limit cycles of discontinuous differential systems by using Picard-Fuchs equations

NASA Astrophysics Data System (ADS)

Yang, Jihua; Zhao, Liqin

2018-05-01

In this paper, by using Picard-Fuchs equations and Chebyshev criterion, we study the upper bounds of the number of limit cycles given by the first order Melnikov function for discontinuous differential systems, which can bifurcate from the periodic orbits of quadratic reversible centers of genus one (r19): x ˙ = y - 12x2 + 16y2, y ˙ = - x - 16 xy, and (r20): x ˙ = y + 4x2, y ˙ = - x + 16 xy, and the periodic orbits of the quadratic isochronous centers (S1) : x ˙ = - y +x2 -y2, y ˙ = x + 2 xy, and (S2) : x ˙ = - y +x2, y ˙ = x + xy. The systems (r19) and (r20) are perturbed inside the class of polynomial differential systems of degree n and the system (S1) and (S2) are perturbed inside the class of quadratic polynomial differential systems. The discontinuity is the line y = 0. It is proved that the upper bounds of the number of limit cycles for systems (r19) and (r20) are respectively 4 n - 3 (n ≥ 4) and 4 n + 3 (n ≥ 3) counting the multiplicity, and the maximum numbers of limit cycles bifurcating from the period annuluses of the isochronous centers (S1) and (S2) are exactly 5 and 6 (counting the multiplicity) on each period annulus respectively.

Importance of Air Absorption During Mechanical Integrity Testing

NASA Astrophysics Data System (ADS)

Arnold, Fredric C.

1990-11-01

Wells used for injection of liquid industrial waste into deep saline aquifers are required to be periodically tested for mechanical integrity. A generally accepted method to demonstrate mechanical integrity is to pressurize the casing-tubing annulus and monitor any decline in pressure. If air is used to pressurize the annulus, uncertainty may exist in differentiating between absorption of air into water in the annulus and loss of pressure due to the absence of mechanical integrity. An analytical model of air absorbance has been derived and used to quantify the pressure decline due to dissolving and diffusion of the air in annular water. A parameteric study was made to determine when annular pressure decline due to absorption of air is significant.

Combined natural convection and non-gray radiation heat transfer in a horizontal annulus

NASA Astrophysics Data System (ADS)

Sun, Yujia; Zhang, Xiaobing; Howell, John R.

2018-02-01

Natural convection and non-gray radiation in an annulus containing a radiative participating gas is investigated. To determine the effect of non-gray radiation, the spectral line based weighted sum of gray gas is adopted to model the gas radiative properties. Case with only surface radiation (transparent medium) is also considered to see the relative contributions of surface radiation and gas radiation. The finite volume method is used to solve the mass, momentum, energy and radiative transfer equations. Comparisons between pure convection, case considering only surface radiation and case considering both gas radiation and surface radiation are made and the results show that radiation is not negligible and gas radiation becomes more important with increasing Rayleigh number (and the annulus size).

'Caput medusae': tension reduction on a dehiscent native annulus in valve implantation in an endocarditis case.

PubMed

Albes, Johannes M

2017-12-01

Interrupted pledget-armed braided sutures are widely used for valve implantation. In a 74-year-old woman with aortic valve endocarditis and shallow annular abscess, annulus dehiscence resulted after resection. As resistance was too high for sufficient primary approximation, a snug fit of the valve by means of circumferential application of curbed tourniquets resembling Medusa's head after suture placement was achieved. Closest possible approximation of the upper and lower part of the annulus with the prosthesis prior to final fixation was thus possible, so that application of too much tension on a single suture could be avoided. © The Author 2017. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

Evaluation of Mechanical Ventilator Use with Liquid Oxygen Systems

DTIC Science & Technology

2017-02-22

patients using long-term liquid oxygen differ from those on traditional treatment with oxygen concentrators and/or compressed gas cylinders? A...AFRL-SA-WP-SR-2017-0006 Evaluation of Mechanical Ventilator Use with Liquid Oxygen Systems Thomas Blakeman, MSc, RRT; Dario...To) August 2014 – September 2016 4. TITLE AND SUBTITLE Evaluation of Mechanical Ventilator Use with Liquid Oxygen Systems 5a. CONTRACT NUMBER

Energy Use Consequences of Ventilating a Net-Zero Energy House

PubMed Central

Ng, Lisa C.; Payne, W. Vance

2016-01-01

A Net-Zero Energy Residential Test Facility (NZERTF) has been constructed at the National Institute of Standards and Technology (NIST) in Gaithersburg, Maryland to demonstrate that a home similar in size, aesthetics, and amenities to those in the surrounding communities can achieve net-zero energy use over the course of a year while meeting the average electricity and water use needs of a family of four in the United States. The facility incorporates renewable energy and energy efficient technologies, including an air-to-air heat pump system, a solar photovoltaic system, a solar thermal domestic hot water system, and a heat recovery ventilation system sized to meet American Society of Heating, Refrigeration, and Air-Conditioning Engineers (ASHRAE) Standard 62.2-2010 ventilation requirements. The largest energy end use within the home was space conditioning, which included heat loss through the building envelope, ventilation air supplied by the heat recovery ventilator (HRV), and internal loads. While HRVs are often described as being able to save energy when compared to ventilating without heat recovery, there have been no studies using a full year of measured data that determine the thermal load and energy impacts of HRV-based ventilation on the central heating and cooling system. Over the course of a year, continuous operation of the HRV at the NZERTF resulted in an annual savings of 7 % in heat pump energy use compared with the hypothetical case of ventilating without heat recovery. The heat pump electrical use varied from an increase of 5 % in the cooling months to 36 % savings in the heating months compared with ventilation without heat recovery. The increase in the cooling months occurred when the outdoor temperature was lower than the indoor temperature, during which the availability of an economizer mode would have been beneficial. Nevertheless, the fan energy required to operate the selected HRV at the NZERTF paid for itself in the heat pump energy saved compared with ventilation without heat recovery. PMID:26903776

Energy Use Consequences of Ventilating a Net-Zero Energy House.

PubMed

Ng, Lisa C; Payne, W Vance

2016-03-05

A Net-Zero Energy Residential Test Facility (NZERTF) has been constructed at the National Institute of Standards and Technology (NIST) in Gaithersburg, Maryland to demonstrate that a home similar in size, aesthetics, and amenities to those in the surrounding communities can achieve net-zero energy use over the course of a year while meeting the average electricity and water use needs of a family of four in the United States. The facility incorporates renewable energy and energy efficient technologies, including an air-to-air heat pump system, a solar photovoltaic system, a solar thermal domestic hot water system, and a heat recovery ventilation system sized to meet American Society of Heating, Refrigeration, and Air-Conditioning Engineers (ASHRAE) Standard 62.2-2010 ventilation requirements. The largest energy end use within the home was space conditioning, which included heat loss through the building envelope, ventilation air supplied by the heat recovery ventilator (HRV), and internal loads. While HRVs are often described as being able to save energy when compared to ventilating without heat recovery, there have been no studies using a full year of measured data that determine the thermal load and energy impacts of HRV-based ventilation on the central heating and cooling system. Over the course of a year, continuous operation of the HRV at the NZERTF resulted in an annual savings of 7 % in heat pump energy use compared with the hypothetical case of ventilating without heat recovery. The heat pump electrical use varied from an increase of 5 % in the cooling months to 36 % savings in the heating months compared with ventilation without heat recovery. The increase in the cooling months occurred when the outdoor temperature was lower than the indoor temperature, during which the availability of an economizer mode would have been beneficial. Nevertheless, the fan energy required to operate the selected HRV at the NZERTF paid for itself in the heat pump energy saved compared with ventilation without heat recovery.

46 CFR 127.260 - Ventilation for accommodations.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 4 2010-10-01 2010-10-01 false Ventilation for accommodations. 127.260 Section 127.260... ARRANGEMENTS Particular Construction and Arrangements § 127.260 Ventilation for accommodations. (a) Each... vessel of 100 or more gross tons must be provided with a mechanical ventilation system unless the...

A perfluorochemical loss/restoration (L/R) system for tidal liquid ventilation.

PubMed

Libros, R; Philips, C M; Wolfson, M R; Shaffer, T H

2000-01-01

Tidal liquid ventilation is the transport of dissolved respiratory gases via volume exchange of perfluorochemical (PFC) liquid to and from the PFC-filled lung. All gas-liquid surface tension is eliminated, increasing compliance and providing lung protection due to lower inflation pressures. Tidal liquid ventilation is achieved by cycling fluid from a reservoir to and from the lung by a ventilator. Current approaches are microprocessor-based with feedback control. During inspiration, warmed oxygenated PFC liquid is pumped from a fluid reservoir/gas exchanger into the lung. PFC fluid is conserved by condensing (60-80% efficiency) vapor in the expired gas. A feedback-control system was developed to automatically replace PFC lost due to condenser inefficiency. This loss/restoration (L/R) system consists of a PFC-vapor thermal detector (+/- 2.5%), pneumatics, amplifiers, a gas flow detector (+/- 1%), a PFC pump (+/- 5%), and a controller. Gravimetric studies of perflubron loss from a flask due to evaporation were compared with experimental L/R results and found to be within +/- 1.4%. In addition, when L/R studies were conducted with a previously reported liquid ventilation system over a four-hour period, the L/R system maintained system perflubron volume to within +/- 1% of prime volume and 11.5% of replacement volume, and the difference between experimental PFC loss and that of the L/R system was 1.8 mL/hr. These studies suggest that the PFC L/R system may have significant economic (appropriate dosing for PFC loss) as well as physiologic (maintenance of PFC inventory in the lungs and liquid ventilator) impact on liquid ventilation procedures.

Temperature of gas delivered from ventilators.

PubMed

Chikata, Yusuke; Onodera, Mutsuo; Imanaka, Hideaki; Nishimura, Masaji

2013-01-01

Although heated humidifiers (HHs) are the most efficient humidifying device for mechanical ventilation, some HHs do not provide sufficient humidification when the inlet temperature to the water chamber is high. Because portable and home-care ventilators use turbines, blowers, pistons, or compressors to inhale in ambient air, they may have higher gas temperature than ventilators with piping systems. We carried out a bench study to investigate the temperature of gas delivered from portable and home-care ventilators, including the effects of distance from ventilator outlet, fraction of inspiratory oxygen (FIO2), and minute volume (MV). We evaluated five ventilators equipped with turbine, blower, piston, or compressor system. Ambient air temperature was adjusted to 24°C ± 0.5°C, and ventilation was set at FIO2 0.21, 0.6, and 1.0, at MV 5 and 10 L/min. We analyzed gas temperature at 0, 40, 80, and 120 cm from ventilator outlet and altered ventilator settings. While temperature varied according to ventilators, the outlet gas temperature of ventilators became stable after, at the most, 5 h. Gas temperature was 34.3°C ± 3.9°C at the ventilator outlet, 29.5°C ± 2.2°C after 40 cm, 25.4°C ± 1.2°C after 80 cm and 25.1°C ± 1.2°C after 120 cm (P < 0.01). FIO2 and MV did not affect gas temperature. Gas delivered from portable and home-care ventilator was not too hot to induce heated humidifier malfunctioning. Gas soon declined when passing through the limb.

Supply Ventilation and Prevention of Carbon Monoxide (II) Ingress into Building Premises

NASA Astrophysics Data System (ADS)

Litvinova, N. A.

2017-11-01

The article contains the relationships of carbon monoxide (II) concentration versus height-above-ground near buildings derived based on results of studies. The results of studies are crucial in preventing external pollutants ingress into a ventilation system. Being generated by external emission sources, such as motor vehicles and city heating plants, carbon monoxide (II) enters the premises during operation of a supply ventilation system. Fresh air nomographic charts were drawn to select the height of a fresh air intake into the ventilation system. Nomographic charts take into account external sources. The selected emission sources are located at various levels above ground relative to the building. The recommendations allow designing supply ventilation taking into account the quality of ambient air through the whole building height.

Mechanical ventilation in disaster situations: a new paradigm using the AGILITIES Score System.

PubMed

Wilkens, Eric P; Klein, Gary M

2010-01-01

The failure of life-critical systems such as mechanical ventilators in the wake of a pandemic or a disaster may result in death, and therefore, state and federal government agencies must have precautions in place to ensure availability, reliability, and predictability through comprehensive preparedness and response plans. All 50 state emergency preparedness response plans were extensively examined for the attention given to the critically injured and ill patient population during a pandemic or mass casualty event. Public health authorities of each state were contacted as well. Nine of 51 state plans (17.6 percent) included a plan or committee for mechanical ventilation triage and management in a pandemic influenza event. All 51 state plans relied on the Centers for Disease Control and Prevention Flu Surge 2.0 spreadsheet to provide estimates for their influenza planning. In the absence of more specific guidance, the authors have developed and provided guidelines recommended for ventilator triage and the implementation of the AGILITIES Score in the event of a pandemic, mass casualty event, or other catastrophic disaster. The authors present and describe the AGILITIES Score Ventilator Triage System and provide related guidelines to be adopted uniformly by government agencies and hospitals. This scoring system and the set ofguidelines are to be used iA disaster settings, such as Hurricane Katrina, and are based on three key factors: relative health, duration of time on mechanical ventilation, and patients' use of resources during a disaster. For any event requiring large numbers of ventilators for patients, the United States is woefully unprepared. The deficiencies in this aspect of preparedness include (1) lack of accountability for physical ventilators, (2) lack of understanding with which healthcare professionals can safely operate these ventilators, (3) lack of understanding from where additional ventilator resources exist, and (4) a triage strategy to provide ventilator support to those patients with the greatest chances of survival.

Tunnel Ventilation Control Using Reinforcement Learning Methodology

NASA Astrophysics Data System (ADS)

Chu, Baeksuk; Kim, Dongnam; Hong, Daehie; Park, Jooyoung; Chung, Jin Taek; Kim, Tae-Hyung

The main purpose of tunnel ventilation system is to maintain CO pollutant concentration and VI (visibility index) under an adequate level to provide drivers with comfortable and safe driving environment. Moreover, it is necessary to minimize power consumption used to operate ventilation system. To achieve the objectives, the control algorithm used in this research is reinforcement learning (RL) method. RL is a goal-directed learning of a mapping from situations to actions without relying on exemplary supervision or complete models of the environment. The goal of RL is to maximize a reward which is an evaluative feedback from the environment. In the process of constructing the reward of the tunnel ventilation system, two objectives listed above are included, that is, maintaining an adequate level of pollutants and minimizing power consumption. RL algorithm based on actor-critic architecture and gradient-following algorithm is adopted to the tunnel ventilation system. The simulations results performed with real data collected from existing tunnel ventilation system and real experimental verification are provided in this paper. It is confirmed that with the suggested controller, the pollutant level inside the tunnel was well maintained under allowable limit and the performance of energy consumption was improved compared to conventional control scheme.

Buildings operations and ETS exposure.

PubMed Central

Spengler, J D

1999-01-01

Mechanical systems are used in buildings to provide conditioned air, dissipate thermal loads, dilute contaminants, and maintain pressure differences. The characteristics of these systems and their operations h implications for the exposures of workers to environmental tobacco smoke (ETS) and for the control of these exposures. This review describes the general features of building ventilation systems and the efficacy of ventilation for controlling contaminant concentrations. Ventilation can reduce the concentration of ETS through dilution, but central heating, ventilating, and air conditioning (HVAC) can also move air throughout a building that has been contaminated by ETS. An understanding of HVAC systems is needed to develop models for exposures of workers to ETS. Images Figure 1 Figure 2 Figure 3 PMID:10375293

Bacterial burden in the operating room: impact of airflow systems.

PubMed

Hirsch, Tobias; Hubert, Helmine; Fischer, Sebastian; Lahmer, Armin; Lehnhardt, Marcus; Steinau, Hans-Ulrich; Steinstraesser, Lars; Seipp, Hans-Martin

2012-09-01

Wound infections present one of the most prevalent and frequent complications associated with surgical procedures. This study analyzes the impact of currently used ventilation systems in the operating room to reduce bacterial contamination during surgical procedures. Four ventilation systems (window-based ventilation, supported air nozzle canopy, low-turbulence displacement airflow, and low-turbulence displacement airflow with flow stabilizer) were analyzed. Two hundred seventy-seven surgical procedures in 6 operating rooms of 5 different hospitals were analyzed for this study. Window-based ventilation showed the highest intraoperative contamination (13.3 colony-forming units [CFU]/h) followed by supported air nozzle canopy (6.4 CFU/h; P = .001 vs window-based ventilation) and low-turbulence displacement airflow (3.4 and 0.8 CFU/h; P < .001 vs window-based ventilation and supported air nozzle canopy). The highest protection was provided by the low-turbulence displacement airflow with flow stabilizer (0.7 CFU/h), which showed a highly significant difference compared with the best supported air nozzle canopy theatre (3.9 CFU/h; P < .001). Furthermore, this system showed no increase of contamination in prolonged durations of surgical procedures. This study shows that intraoperative contamination can be significantly reduced by the use of adequate ventilation systems. Copyright © 2012 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Mosby, Inc. All rights reserved.

46 CFR 194.15-5 - Ventilation.

Code of Federal Regulations, 2011 CFR

2011-10-01

....15-5 Ventilation. (a) Operations, reactions or experiments which produce toxic, noxious or corrosive...) Ventilation of air conditioning systems serving the chemical laboratory shall be designed so that air cannot...

FiO2 delivered by a turbine portable ventilator with an oxygen concentrator in an Austere environment.

PubMed

Bordes, Julien; Erwan d'Aranda; Savoie, Pierre-Henry; Montcriol, Ambroise; Goutorbe, Philippe; Kaiser, Eric

2014-09-01

Management of critically ill patients in austere environments is a logistic challenge. Availability of oxygen cylinders for the mechanically ventilated patient may be difficult in such a context. A solution is to use a ventilator able to function with an oxygen concentrator. We tested the SeQual Integra™ (SeQual, San Diego, CA) 10-OM oxygen concentrator paired with the Pulmonetic System(®) LTV 1000 ventilator (Pulmonetic Systems, Minneapolis, MN) and evaluated the delivered fraction of inspired oxygen (FiO2) across a range of minute volumes and combinations of ventilator settings. Two LTV 1000 ventilators were tested. The ventilators were attached to a test lung and FiO2 was measured by a gas analyzer. Continuous-flow oxygen was generated by the OC from 0.5 L/min to 10 L/min and injected into the oxygen inlet port of the LTV 1000. Several combinations of ventilator settings were evaluated to determine the factors affecting the delivered FiO2. The LTV 1000 ventilator is a turbine ventilator that is able to deliver high FiO2 when functioning with an oxygen concentrator. However, modifications of the ventilator settings such as increase in minute ventilation affect delivered FiO2 even if oxygen flow is constant on the oxygen concentrator. The ability of an oxygen concentrator to deliver high FiO2 when used with a turbine ventilator makes this method of oxygen delivery a viable alternative to cylinders in austere environments when used with a turbine ventilator. However, FiO2 has to be monitored continuously because delivered FiO2 decreases when minute ventilation is increased. Copyright © 2014 Elsevier Inc. All rights reserved.

A concentrated parameter model for the human cardiovascular system including heart valve dynamics and atrioventricular interaction.

PubMed

Korakianitis, Theodosios; Shi, Yubing

2006-09-01

Numerical modeling of the human cardiovascular system has always been an active research direction since the 19th century. In the past, various simulation models of different complexities were proposed for different research purposes. In this paper, an improved numerical model to study the dynamic function of the human circulation system is proposed. In the development of the mathematical model, the heart chambers are described with a variable elastance model. The systemic and pulmonary loops are described based on the resistance-compliance-inertia concept by considering local effects of flow friction, elasticity of blood vessels and inertia of blood in different segments of the blood vessels. As an advancement from previous models, heart valve dynamics and atrioventricular interaction, including atrial contraction and motion of the annulus fibrosus, are specifically modeled. With these improvements the developed model can predict several important features that were missing in previous numerical models, including regurgitant flow on heart valve closure, the value of E/A velocity ratio in mitral flow, the motion of the annulus fibrosus (called the KG diaphragm pumping action), etc. These features have important clinical meaning and their changes are often related to cardiovascular diseases. Successful simulation of these features enhances the accuracy of simulations of cardiovascular dynamics, and helps in clinical studies of cardiac function.

The Effect of Surface Topography on the Nonlinear Dynamics of Rossby Waves

NASA Technical Reports Server (NTRS)

Abarzhi, S. I.; Desjardins, O.; Pitsch, H.

2003-01-01

Boussinesq convection in rotating systems attracts a sustained attention of the fluid dynamics community, because it has intricate non-linear dynamics (Cross & Hohenberg 1993) and plays an important role in geophysical and astrophysical applications, such as the motion of the liquid outer core of Earth, the Red Spot in Jupiter, the giant cells in the Sun etc. (Alridge et al. 1990). A fundamental distinction between the real geo- and astrophysical problems and the idealized laboratory studies is that natural systems are inhomogeneous (Alridge et al. 1990). Heterogeneities modulate the flow and influence significantly the dynamics of convective patterns (Alridge et al. 1990; Hide 1971). The effect of modulations on pattern formation and transition to turbulence in Boussinesq convection is far from being completely understood (Cross & Hohenberg 1993; Aranson & Kramer 2002). It is generally accepted that in the liquid outer core of the Earth the transport of the angular momentum and internal heat occurs via thermal Rossby waves (Zhang et al. 2001; Kuang & Bloxham 1999). These waves been visualized in laboratory experiments in rotating liquid-filled spheres and concentric spherical shells (Zhang et al. 2001; Kuang & Bloxham 1999). The basic dynamical features of Rossby waves have been reproduced in a cylindrical annulus, a system much simpler than the spherical ones (Busse & Or 1986; Or & Busse 1987). For convection in a cylindrical annulus, the fluid motion is two-dimensional, and gravity is replaced by a centrifugal force, (Busse & Or 1986; Or & Busse 1987). Hide (1971) has suggested that the momentum and heat transport in the core might be influenced significantly by so-called bumps, which are heterogeneities on the mantle-core boundary. To model the effect of surface topography on the transport of momentum and energy in the liquid outer core of the Earth, Bell & Soward (1996), Herrmann & Busse (1998) and Westerburg & Busse (2001) have studied the nonlinear dynamics of thermal Rossby waves in a cylindrical annulus with azimuthally modulated height.

Multidetector computed tomography sizing of aortic annulus prior to transcatheter aortic valve replacement (TAVR): Variability and impact of observer experience.

PubMed

Le Couteulx, S; Caudron, J; Dubourg, B; Cauchois, G; Dupré, M; Michelin, P; Durand, E; Eltchaninoff, H; Dacher, J-N

2018-05-01

To evaluate intra- and inter-observer variability of multidetector computed tomography (MDCT) sizing of the aortic annulus before transcatheter aortic valve replacement (TAVR) and the effect of observer experience, aortic valve calcification and image quality. MDCT examinations of 52 consecutive patients with tricuspid aortic valve (30 women, 22 men) with a mean age of 83±7 (SD) years (range: 64-93 years) were evaluated retrospectively. The maximum and minimum diameters, area and circumference of the aortic annulus were measured twice at diastole and systole with a standardized approach by three independent observers with different levels of experience (expert [observer 1]; resident with intensive 6 months practice [observer 2]; trained resident with starting experience [observer 3]). Observers were requested to recommend the valve prosthesis size. Calcification volume of the aortic valve and signal to noise ratio were evaluated. Intra- and inter-observer reproducibility was excellent for all aortic annulus dimensions, with an intraclass correlation coefficient ranging respectively from 0.84 to 0.98 and from 0.82 to 0.97. Agreement for selection of prosthesis size was almost perfect between the two most experienced observers (k=0.82) and substantial with the inexperienced observer (k=0.67). Aortic valve calcification did not influence intra-observer reproducibility. Image quality influenced reproducibility of the inexperienced observer. Intra- and inter-observer variability of aortic annulus sizing by MDCT is low. Nevertheless, the less experienced observer showed lower reliability suggesting a learning curve. Copyright © 2017. Published by Elsevier Masson SAS.

A Structurally and Functionally Biomimetic Biphasic Scaffold for Intervertebral Disc Tissue Engineering

PubMed Central

Choy, Andrew Tsz Hang; Chan, Barbara Pui

2015-01-01

Tissue engineering offers high hopes for the treatment of intervertebral disc (IVD) degeneration. Whereas scaffolds of the disc nucleus and annulus have been extensively studied, a truly biomimetic and mechanically functional biphasic scaffold using naturally occurring extracellular matrix is yet to be developed. Here, a biphasic scaffold was fabricated with collagen and glycosaminoglycans (GAGs), two of the most abundant extracellular matrix components in the IVD. Following fabrication, the scaffold was characterized and benchmarked against native disc. The biphasic scaffold was composed of a collagen-GAG co-precipitate making up the nucleus pulposus-like core, and this was encapsulated in multiple lamellae of photochemically crosslinked collagen membranes comprising the annulus fibrosus-like lamellae. On mechanical testing, the height of our engineered disc recovered by ~82-89% in an annulus-independent manner, when compared with the 99% recovery exhibited by native disc. The annulus-independent nature of disc height recovery suggests that the fluid replacement function of the engineered nucleus pulposus core might mimic this hitherto unique feature of native disc. Biphasic scaffolds comprised of 10 annulus fibrosus-like lamellae had the best overall mechanical performance among the various designs owing to their similarity to native disc in most aspects, including elastic compliance during creep and recovery, and viscous compliance during recovery. However, the dynamic mechanical performance (including dynamic stiffness and damping factor) of all the biphasic scaffolds was similar to that of the native discs. This study contributes to the rationalized design and development of a biomimetic and mechanically viable biphasic scaffold for IVD tissue engineering. PMID:26115332

Why do some intervertebral discs degenerate, when others (in the same spine) do not?

PubMed

Adams, Michael A; Lama, Polly; Zehra, Uruj; Dolan, Patricia

2015-03-01

This review suggests why some discs degenerate rather than age normally. Intervertebral discs are avascular pads of fibrocartilage that allow movement between vertebral bodies. Human discs have a low cell density and a limited ability to adapt to mechanical demands. With increasing age, the matrix becomes yellowed, fibrous, and brittle, but if disc structure remains intact, there is little impairment in function, and minimal ingrowth of blood vessels or nerves. Approximately half of old lumbar discs degenerate in the sense of becoming physically disrupted. The posterior annulus and lower lumbar discs are most affected, presumably because they are most heavily loaded. Age and genetic inheritance can weaken discs to such an extent that they are physically disrupted during everyday activities. Damage to the endplate or annulus typically decompresses the nucleus, concentrates stress within the annulus, and allows ingrowth of nerves and blood vessels. Matrix disruption progresses by mechanical and biological means. The site of initial damage leads to two disc degeneration "phenotypes": endplate-driven degeneration is common in the upper lumbar and thoracic spine, and annulus-driven degeneration is common at L4-S1. Discogenic back pain can be initiated by tissue disruption, and amplified by inflammation and infection. Healing is possible in the outer annulus only, where cell density is highest. We conclude that some discs degenerate because they are disrupted by excessive mechanical loading. This can occur without trauma if tissues are weakened by age and genetic inheritance. Moderate mechanical loading, in contrast, strengthens all spinal tissues, including discs. © 2014 Wiley Periodicals, Inc.

A technique of snaring method for fitting a prosthetic valve into the annulus.

PubMed

Nagasaka, Shigeo; Kawata, Tetsuji; Matsuta, Masahiro; Taniguchi, Shigeki

2005-01-01

Tourniquetting technique to fit a prosthetic valve (PV) into the annulus in valve replacement surgery has been previously reported. We modified the previously reported method and designed a simpler tying technique. We performed 11 aortic (AVR: including four cases for calcified aortic stenosis (AS) with a small annulus and one cases for infective endocarditis with intramuscular abscess cavity), eight mitral valve replacements (MVR), and one tricuspid valve replacement (TVR: for corrected transposition of the great arteries). A PV was implanted using 2-0 polyester mattress sutures with a pledget. Each of the two tourniquets held a suture at the bottom of the annulus and at the opposite position to fit a PV. The sutures between each snare were tied down from the bottom to the top. In MVR, after seating of a PV with two tourniquets, we could make sure that no native tissue of any preserved mitral apparatus disturbed PV leaflet motion. In calcific AS, a PV had a good fitting into the annulus because of tourniquets applied to unseated part during tying sutures. In AVR for infective endocarditis, mattress sutures supported by a Teflon pledget were placed to close the abscess cavity. After snaring on one of these sutures, we tied down the sutures, ensuring that they did not cut through the friable tissues. In TVR, we found that native leaflets interfered with PV motion after seating down the prosthesis and those leaflets were resected before tying down the sutures. Postoperative transesophageal echocardiography showed no paravalvular leakage in any patients and excellent PV functions.

Size-selective mortality of steelhead during freshwater and marine life stages related to freshwater growth in the Skagit River, Washington

USGS Publications Warehouse

Thompson, Jamie N.; Beauchamp, David A.

2014-01-01

We evaluated freshwater growth and survival from juvenile (ages 0–3) to smolt (ages 1–5) and adult stages in wild steelhead Oncorhynchus mykiss sampled in different precipitation zones of the Skagit River basin, Washington. Our objectives were to determine whether significant size-selective mortality (SSM) in steelhead could be detected between early and later freshwater stages and between each of these freshwater stages and returning adults and, if so, how SSM varied between these life stages and mixed and snow precipitation zones. Scale-based size-at-annulus comparisons indicated that steelhead in the snow zone were significantly larger at annulus 1 than those in the mixed rain–snow zone. Size at annuli 2 and 3 did not differ between precipitation zones, and we found no precipitation zone × life stage interaction effect on size at annulus. Significant freshwater and marine SSM was evident between the juvenile and adult samples at annulus 1 and between each life stage at annuli 2 and 3. Rapid growth between the final freshwater annulus and the smolt migration did not improve survival to adulthood; rather, it appears that survival in the marine environment may be driven by an overall higher growth rate set earlier in life, which results in a larger size at smolt migration. Efforts for recovery of threatened Puget Sound steelhead could benefit by considering that SSM between freshwater and marine life stages can be partially attributed to growth attained in freshwater habitats and by identifying those factors that limit growth during early life stages.

Particulate matter in animal rooms housing mice in microisolation caging.

PubMed

Langham, Gregory L; Hoyt, Robert F; Johnson, Thomas E

2006-11-01

Reactions to allergens created by laboratory animals are among the most frequently encountered occupational illnesses associated with research animals. Personnel are exposed to these allergens through airborne particulate matter. Although the use of microisolation caging systems can reduce particulate matter concentrations in rooms housing mice, the operating parameters of ventilated caging systems vary extensively. We compared room air in mouse rooms containing 5 different types of caging: 1) individually ventilated caging under positive pressure with filtered intake air and exhaust air returned to the room (VCR+), 2) individually ventilated caging under negative pressure with exhaust air returned to the room (VCR-), 3) individually ventilated caging under positive pressure with exhaust air returned to the heating, ventilation, and air-conditioning (HVAC) system, 4) individually ventilated caging under negative pressure with exhaust air returned to the HVAC system, and 5) static microisolation cages. We found that rooms under VCR conditions had fewer large particles than did those under other conditions, but the numbers of 0.3 microm particles did not differ significantly among systems. Static, positive or negative pressure applied to caging units as well as route of air exhaust were found to have little influence on the total number of particles in the atmosphere. Therefore, considering the heat load, odor, and overall particulate concentration in the room, placing individually ventilated caging under negative pressure with exhaust air returned to the HVAC system appears to be the optimal overall choice when using microisolation housing for rodents.

Particle transport in low-energy ventilation systems. Part 1: theory of steady states.

PubMed

Bolster, D T; Linden, P F

2009-04-01

Many modern low-energy ventilation schemes, such as displacement or natural ventilation, take advantage of temperature stratification in a space, extracting the warmest air from the top of the room. The adoption of these energy-efficient ventilation systems still requires the provision of acceptable indoor air quality. In this work we study the steady state transport of particulate contaminants in a displacement-ventilated space. Representing heat sources as ideal sources of buoyancy, analytical models are developed that allow us to compare the average efficiency of contaminant removal between traditional and modern low-energy systems. We found that on average traditional and low-energy systems are similar in overall pollutant removal efficiency, although quite different vertical distributions of contaminant can exist, thus affecting individual exposure. While the main focus of this work is on particles where the dominant mode of deposition is by gravitational settling, we also discuss additional deposition mechanisms and show that the qualitative observations we make carry over to cases where such mechanisms must be included. We illustrate that while average concentration of particles for traditional mixing systems and low energy displacement systems are similar, local concentrations can vary significantly with displacement systems. Depending on the source of the particles this can be better or worse in terms of occupant exposure and engineers should take due diligence accordingly when designing ventilation systems.

Characterization of natural ventilation in wastewater collection systems.

PubMed

Ward, Matthew; Corsi, Richard; Morton, Robert; Knapp, Tom; Apgar, Dirk; Quigley, Chris; Easter, Chris; Witherspoon, Jay; Pramanik, Amit; Parker, Wayne

2011-03-01

The purpose of the study was to characterize natural ventilation in full-scale gravity collection system components while measuring other parameters related to ventilation. Experiments were completed at four different locations in the wastewater collection systems of Los Angeles County Sanitation Districts, Los Angeles, California, and the King County Wastewater Treatment District, Seattle, Washington. The subject components were concrete gravity pipes ranging in diameter from 0.8 to 2.4 m (33 to 96 in.). Air velocity was measured in each pipe using a carbon-monoxide pulse tracer method. Air velocity was measured entering or exiting the components at vents using a standpipe and hotwire anemometer arrangement. Ambient wind speed, temperature, and relative humidity; headspace temperature and relative humidity; and wastewater flow and temperature were measured. The field experiments resulted in a large database of measured ventilation and related parameters characterizing ventilation in full-scale gravity sewers. Measured ventilation rates ranged from 23 to 840 L/s. The experimental data was used to evaluate existing ventilation models. Three models that were based upon empirical extrapolation, computational fluid dynamics, and thermodynamics, respectively, were evaluated based on predictive accuracy compared to the measured data. Strengths and weaknesses in each model were found and these observations were used to propose a concept for an improved ventilation model.

Scala tympani cochleostomy II: topography and histology.

PubMed

Adunka, Oliver F; Radeloff, Andreas; Gstoettner, Wolfgang K; Pillsbury, Harold C; Buchman, Craig A

2007-12-01

To assess intracochlear trauma using two different round window-related cochleostomy techniques in human temporal bones. Twenty-eight human temporal bones were included in this study. In 21 specimens, cochleostomies were initiated inferior to the round window (RW) annulus. In seven bones, cochleostomies were drilled anterior-inferior to the RW annulus. Limited cochlear implant electrode insertions were performed in 19 bones. In each specimen, promontory anatomy and cochleostomy drilling were photographically documented. Basal cochlear damage was assessed histologically and electrode insertion properties were documented in implanted bones. All implanted specimens showed clear scala tympani electrode placements regardless of cochleostomy technique. All 21 inferior cochleostomies were atraumatic. Anterior-inferior cochleostomies resulted in various degrees of intracochlear trauma in all seven bones. For atraumatic opening of the scala tympani using a cochleostomy approach, initiation of drilling should proceed from inferior to the round window annulus, with gradual progression toward the undersurface of the lumen. While cochleostomies initiated anterior-inferior to the round window annulus resulted in scala tympani opening, many of these bones displayed varying degrees of intracochlear trauma that may result in hearing loss. When intracochlear drilling is avoided, the anterior bony margin of the cochleostomy remains a significant intracochlear impediment to in-line electrode insertion.

Are we fully utilizing the functionalities of modern operating room ventilators?

PubMed

Liu, Shujie; Kacmarek, Robert M; Oto, Jun

2017-12-01

The modern operating room ventilators have become very sophisticated and many of their features are comparable with those of an ICU ventilator. To fully utilize the functionality of modern operating room ventilators, it is important for clinicians to understand in depth the working principle of these ventilators and their functionalities. Piston ventilators have the advantages of delivering accurate tidal volume and certain flow compensation functions. Turbine ventilators have great ability of flow compensation. Ventilation modes are mainly volume-based or pressure-based. Pressure-based ventilation modes provide better leak compensation than volume-based. The integration of advanced flow generation systems and ventilation modes of the modern operating room ventilators enables clinicians to provide both invasive and noninvasive ventilation in perioperative settings. Ventilator waveforms can be used for intraoperative neuromonitoring during cervical spine surgery. The increase in number of new features of modern operating room ventilators clearly creates the opportunity for clinicians to optimize ventilatory care. However, improving the quality of ventilator care relies on a complete understanding and correct use of these new features. VIDEO ABSTRACT: http://links.lww.com/COAN/A47.

Houses need to breathe--right?

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

Sherman, Max H.

2004-10-01

Houses need to breathe, but we can no longer leave the important functions associated with ventilation to be met accidentally. A designed ventilation system must be considered as much a part of a home as its heating system. Windows are a key part of that system because they allow a quick increase in ventilation for unusual events, but neither they nor a leaky building shell can be counted on to provide minimum levels.

Minimally Invasive Aortic Valve Replacement Following Root Enlargement on too Narrow Annulus to Perform Transcatheter Aortic Valve Implantation.

PubMed

Sakamoto, Kosuke; Totsugawa, Toshinori; Hiraoka, Arudo; Tamura, Kentaro; Yoshitaka, Hidenori; Sakaguchi, Taichi

2018-05-30

An 88-year-old woman was diagnosed with aortic stenosis and an aortic annulus that was too narrow to perform transcatheter aortic valve implantation. Surgery was performed through a 7-cm right mini-thoracotomy at the fourth intercostal space. A 19-mm aortic valve bioprosthesis was implanted after root enlargement. The fourth intercostal space was a suitable site for aortic root enlargement because of the shorter skin-to-root distance and the detailed exposure of the aortic valve after cutting the aortic wall. This study concluded that minimally-invasive aortic valve replacement following root enlargement can be an option for the treatment of elderly patients with aortic stenosis accompanied by an annulus that is too small to perform transcatheter aortic valve implantation.

Ventilating Air-Conditioner

NASA Technical Reports Server (NTRS)

Dinh, Khanh

1994-01-01

Air-conditioner provides ventilation designed to be used alone or incorporated into cooling or heating system operates efficiently only by recirculating stale air within building. Energy needed to operate overall ventilating cooling or heating system slightly greater than operating nonventilating cooling or heating system. Helps to preserve energy efficiency while satisfying need for increased forced ventilation to prevent accumulation of undesired gases like radon and formaldehyde. Provides fresh treated air to variety of confined spaces: hospital surgeries, laboratories, clean rooms, and printing shops and other places where solvents used. In mobile homes and portable classrooms, eliminates irritant chemicals exuded by carpets, panels, and other materials, ensuring healthy indoor environment for occupants.

Assessing Respiratory System Mechanical Function.

PubMed

Restrepo, Ruben D; Serrato, Diana M; Adasme, Rodrigo

2016-12-01

The main goals of assessing respiratory system mechanical function are to evaluate the lung function through a variety of methods and to detect early signs of abnormalities that could affect the patient's outcomes. In ventilated patients, it has become increasingly important to recognize whether respiratory function has improved or deteriorated, whether the ventilator settings match the patient's demand, and whether the selection of ventilator parameters follows a lung-protective strategy. Ventilator graphics, esophageal pressure, intra-abdominal pressure, and electric impedance tomography are some of the best-known monitoring tools to obtain measurements and adequately evaluate the respiratory system mechanical function. Copyright © 2016 Elsevier Inc. All rights reserved.

78 FR 51749 - Proposed Information Collection; Ventilation Plan and Main Fan Maintenance Record (Pertains to...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-08-21

... maintaining a safe and healthful working environment. A well planned mine ventilation system is necessary to assure a fresh air supply to miners at all working places, to control the amounts of harmful airborne... usually present harsh and hostile working environments. The ventilation system is the most vital life...

Clinical challenges in mechanical ventilation.

PubMed

Goligher, Ewan C; Ferguson, Niall D; Brochard, Laurent J

2016-04-30

Mechanical ventilation supports gas exchange and alleviates the work of breathing when the respiratory muscles are overwhelmed by an acute pulmonary or systemic insult. Although mechanical ventilation is not generally considered a treatment for acute respiratory failure per se, ventilator management warrants close attention because inappropriate ventilation can result in injury to the lungs or respiratory muscles and worsen morbidity and mortality. Key clinical challenges include averting intubation in patients with respiratory failure with non-invasive techniques for respiratory support; delivering lung-protective ventilation to prevent ventilator-induced lung injury; maintaining adequate gas exchange in severely hypoxaemic patients; avoiding the development of ventilator-induced diaphragm dysfunction; and diagnosing and treating the many pathophysiological mechanisms that impair liberation from mechanical ventilation. Personalisation of mechanical ventilation based on individual physiological characteristics and responses to therapy can further improve outcomes. Copyright © 2016 Elsevier Ltd. All rights reserved.

46 CFR 58.01-45 - Machinery space, ventilation.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 2 2011-10-01 2011-10-01 false Machinery space, ventilation. 58.01-45 Section 58.01-45... MACHINERY AND RELATED SYSTEMS General Requirements § 58.01-45 Machinery space, ventilation. Each machinery space must be ventilated to ensure that, when machinery or boilers are operating at full power in all...

46 CFR 58.01-45 - Machinery space, ventilation.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 2 2014-10-01 2014-10-01 false Machinery space, ventilation. 58.01-45 Section 58.01-45... MACHINERY AND RELATED SYSTEMS General Requirements § 58.01-45 Machinery space, ventilation. Each machinery space must be ventilated to ensure that, when machinery or boilers are operating at full power in all...

46 CFR 58.01-45 - Machinery space, ventilation.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 2 2012-10-01 2012-10-01 false Machinery space, ventilation. 58.01-45 Section 58.01-45... MACHINERY AND RELATED SYSTEMS General Requirements § 58.01-45 Machinery space, ventilation. Each machinery space must be ventilated to ensure that, when machinery or boilers are operating at full power in all...

46 CFR 58.01-45 - Machinery space, ventilation.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 2 2013-10-01 2013-10-01 false Machinery space, ventilation. 58.01-45 Section 58.01-45... MACHINERY AND RELATED SYSTEMS General Requirements § 58.01-45 Machinery space, ventilation. Each machinery space must be ventilated to ensure that, when machinery or boilers are operating at full power in all...

46 CFR 58.01-45 - Machinery space, ventilation.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 2 2010-10-01 2010-10-01 false Machinery space, ventilation. 58.01-45 Section 58.01-45... MACHINERY AND RELATED SYSTEMS General Requirements § 58.01-45 Machinery space, ventilation. Each machinery space must be ventilated to ensure that, when machinery or boilers are operating at full power in all...

46 CFR 177.600 - Ventilation of enclosed and partially enclosed spaces.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 7 2010-10-01 2010-10-01 false Ventilation of enclosed and partially enclosed spaces... enclosed and partially enclosed spaces. (a) An enclosed or partially enclosed space within a vessel must be adequately ventilated in a manner suitable for the purpose of the space. (b) A power ventilation system must...

46 CFR 116.600 - Ventilation of enclosed and partially enclosed spaces.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 4 2011-10-01 2011-10-01 false Ventilation of enclosed and partially enclosed spaces... spaces. (a) An enclosed or partially enclosed space within a vessel must be adequately ventilated in a manner suitable for the purpose of the space. (b) A power ventilation system must be capable of being...

46 CFR 116.600 - Ventilation of enclosed and partially enclosed spaces.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 4 2013-10-01 2013-10-01 false Ventilation of enclosed and partially enclosed spaces... spaces. (a) An enclosed or partially enclosed space within a vessel must be adequately ventilated in a manner suitable for the purpose of the space. (b) A power ventilation system must be capable of being...

46 CFR 116.600 - Ventilation of enclosed and partially enclosed spaces.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 4 2014-10-01 2014-10-01 false Ventilation of enclosed and partially enclosed spaces... spaces. (a) An enclosed or partially enclosed space within a vessel must be adequately ventilated in a manner suitable for the purpose of the space. (b) A power ventilation system must be capable of being...

46 CFR 177.600 - Ventilation of enclosed and partially enclosed spaces.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 7 2014-10-01 2014-10-01 false Ventilation of enclosed and partially enclosed spaces... enclosed and partially enclosed spaces. (a) An enclosed or partially enclosed space within a vessel must be adequately ventilated in a manner suitable for the purpose of the space. (b) A power ventilation system must...

46 CFR 177.600 - Ventilation of enclosed and partially enclosed spaces.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 7 2013-10-01 2013-10-01 false Ventilation of enclosed and partially enclosed spaces... enclosed and partially enclosed spaces. (a) An enclosed or partially enclosed space within a vessel must be adequately ventilated in a manner suitable for the purpose of the space. (b) A power ventilation system must...

46 CFR 116.600 - Ventilation of enclosed and partially enclosed spaces.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 4 2012-10-01 2012-10-01 false Ventilation of enclosed and partially enclosed spaces... spaces. (a) An enclosed or partially enclosed space within a vessel must be adequately ventilated in a manner suitable for the purpose of the space. (b) A power ventilation system must be capable of being...

46 CFR 116.600 - Ventilation of enclosed and partially enclosed spaces.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 4 2010-10-01 2010-10-01 false Ventilation of enclosed and partially enclosed spaces... spaces. (a) An enclosed or partially enclosed space within a vessel must be adequately ventilated in a manner suitable for the purpose of the space. (b) A power ventilation system must be capable of being...

46 CFR 177.600 - Ventilation of enclosed and partially enclosed spaces.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 7 2011-10-01 2011-10-01 false Ventilation of enclosed and partially enclosed spaces... enclosed and partially enclosed spaces. (a) An enclosed or partially enclosed space within a vessel must be adequately ventilated in a manner suitable for the purpose of the space. (b) A power ventilation system must...

46 CFR 177.600 - Ventilation of enclosed and partially enclosed spaces.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 7 2012-10-01 2012-10-01 false Ventilation of enclosed and partially enclosed spaces... enclosed and partially enclosed spaces. (a) An enclosed or partially enclosed space within a vessel must be adequately ventilated in a manner suitable for the purpose of the space. (b) A power ventilation system must...

Limiting ventilator-induced lung injury through individual electronic medical record surveillance.

PubMed

Herasevich, Vitaly; Tsapenko, Mykola; Kojicic, Marija; Ahmed, Adil; Kashyap, Rachul; Venkata, Chakradhar; Shahjehan, Khurram; Thakur, Sweta J; Pickering, Brian W; Zhang, Jiajie; Hubmayr, Rolf D; Gajic, Ognjen

2011-01-01

To improve the safety of ventilator care and decrease the risk of ventilator-induced lung injury, we designed and tested an electronic algorithm that incorporates patient characteristics and ventilator settings, allowing near-real-time notification of bedside providers about potentially injurious ventilator settings. Electronic medical records of consecutive patients who received invasive ventilation were screened in three Mayo Clinic Rochester intensive care units. The computer system alerted bedside providers via the text paging notification about potentially injurious ventilator settings. Alert criteria included a Pao2/Fio2 ratio of <300 mm Hg, free text search for the words "edema" or "bilateral + infiltrates" on the chest radiograph report, a tidal volume of >8 mL/kg predicted body weight (based on patient gender and height), a plateau pressure of >30 cm H2O, and a peak airway pressure of >35 cm H2O. Respiratory therapists answered a brief online satisfaction survey. Ventilator-induced lung injury risk was compared before and after the introduction of ventilator-induced lung injury alert. The prevalence of acute lung injury was 42% (n = 490) among 1,159 patients receiving >24 hrs of invasive ventilation. The system sent 111 alerts for 80 patients, with a positive predictive value of 59%. The exposure to potentially injurious ventilation decreased after the intervention from 40.6 ± 74.6 hrs to 26.9 ± 77.3 hrs (p = .004). Electronic medical record surveillance of mechanically ventilated patients accurately detects potentially injurious ventilator settings and is able to influence bedside practice at moderate costs. Its implementation is associated with decreased patient exposure to potentially injurious mechanical ventilation settings.

Hygiene guideline for the planning, installation, and operation of ventilation and air-conditioning systems in health-care settings - Guideline of the German Society for Hospital Hygiene (DGKH).

PubMed

Külpmann, Rüdiger; Christiansen, Bärbel; Kramer, Axel; Lüderitz, Peter; Pitten, Frank-Albert; Wille, Frank; Zastrow, Klaus-Dieter; Lemm, Friederike; Sommer, Regina; Halabi, Milo

2016-01-01

Since the publication of the first "Hospital Hygiene Guideline for the implementation and operation of air conditioning systems (HVAC systems) in hospitals" (http://www.krankenhaushygiene.de/informationen/fachinformationen/leitlinien/12) in 2002, it was necessary due to the increase in knowledge, new regulations, improved air-conditioning systems and advanced test methods to revise the guideline. Based on the description of the basic features of ventilation concepts, its hygienic test and the usage-based requirements for ventilation, the DGKH section "Ventilation and air conditioning technology" attempts to provide answers for the major air quality issues in the planning, design and the hygienically safe operation of HVAC systems in rooms of health care.

The School Advanced Ventilation Engineering Software (SAVES)

EPA Pesticide Factsheets

The School Advanced Ventilation Engineering Software (SAVES) package is a tool to help school designers assess the potential financial payback and indoor humidity control benefits of Energy Recovery Ventilation (ERV) systems for school applications.

Effects of ventilation behaviour on indoor heat load based on test reference years.

PubMed

Rosenfelder, Madeleine; Koppe, Christina; Pfafferott, Jens; Matzarakis, Andreas

2016-02-01

Since 2003, most European countries established heat health warning systems to alert the population to heat load. Heat health warning systems are based on predicted meteorological conditions outdoors. But the majority of the European population spends a substantial amount of time indoors, and indoor thermal conditions can differ substantially from outdoor conditions. The German Meteorological Service (Deutscher Wetterdienst, DWD) extended the existing heat health warning system (HHWS) with a thermal building simulation model to consider heat load indoors. In this study, the thermal building simulation model is used to simulate a standardized building representing a modern nursing home, because elderly and sick people are most sensitive to heat stress. Different types of natural ventilation were simulated. Based on current and future test reference years, changes in the future heat load indoors were analyzed. Results show differences between the various ventilation options and the possibility to minimize the thermal heat stress during summer by using an appropriate ventilation method. Nighttime ventilation for indoor thermal comfort is most important. A fully opened window at nighttime and the 2-h ventilation in the morning and evening are more sufficient to avoid heat stress than a tilted window at nighttime and the 1-h ventilation in the morning and the evening. Especially the ventilation in the morning seems to be effective to keep the heat load indoors low. Comparing the results for the current and the future test reference years, an increase of heat stress on all ventilation types can be recognized.

Effects of ventilation behaviour on indoor heat load based on test reference years

NASA Astrophysics Data System (ADS)

Rosenfelder, Madeleine; Koppe, Christina; Pfafferott, Jens; Matzarakis, Andreas

2016-02-01

Since 2003, most European countries established heat health warning systems to alert the population to heat load. Heat health warning systems are based on predicted meteorological conditions outdoors. But the majority of the European population spends a substantial amount of time indoors, and indoor thermal conditions can differ substantially from outdoor conditions. The German Meteorological Service (Deutscher Wetterdienst, DWD) extended the existing heat health warning system (HHWS) with a thermal building simulation model to consider heat load indoors. In this study, the thermal building simulation model is used to simulate a standardized building representing a modern nursing home, because elderly and sick people are most sensitive to heat stress. Different types of natural ventilation were simulated. Based on current and future test reference years, changes in the future heat load indoors were analyzed. Results show differences between the various ventilation options and the possibility to minimize the thermal heat stress during summer by using an appropriate ventilation method. Nighttime ventilation for indoor thermal comfort is most important. A fully opened window at nighttime and the 2-h ventilation in the morning and evening are more sufficient to avoid heat stress than a tilted window at nighttime and the 1-h ventilation in the morning and the evening. Especially the ventilation in the morning seems to be effective to keep the heat load indoors low. Comparing the results for the current and the future test reference years, an increase of heat stress on all ventilation types can be recognized.

Building Component Maintenance and Repair Data Base: Heating, Ventilating, and Air Conditioning (HVAC) Systems

DTIC Science & Technology

1991-05-01

Building Component Maintenance and Repair Data Base: Heating, Ventilating, and Air Conditioning (HVAC) Systems by Edgar S. Neely Robert D. Neathammer...Repair Data Base: Heating, Ventilating, and Air Conditioning (HVAC) Systems RDTE dated 1980EIMB 1984 - 1989 6. AUTHOR(S) Edgar S. Neely, Robert D...Laboratory (USACERL). The Principal Investigators were Dr. Edgar Neely and Mr. Robert Neathammer (USACERL-FS). The primary contractor for much of the

[Functional tricuspid regurgitation and its relation to the morphology of the tricuspid valve and annulus: pulsed doppler echocardiography and two-dimensional echocardiography].

PubMed

Mikami, T; Kudo, T; Sakurai, N; Sakamoto, S; Tanabe, Y; Yasuda, H

1983-06-01

The mechanism for the development of functional tricuspid regurgitation (TR) was studied by an ultrasonic method. Thirty-five examinations were performed in 31 patients who were expected to have functional TR, and the severity was classified into 4 grades according to the extension of the regurgitant signals by pulsed Doppler echocardiography. The satisfactory horizontal section of the tricuspid valve was obtained by two-dimensional echocardiography (2DE) to measure the tricuspid annular diameter and to observe systolic configuration of the tricuspid valve in 22 examinations. The tricuspid annular diameter was well correlated with the severity of TR, and "lack of coaptation" of the valve was recognized on 2DE in some cases of severe TR with the markedly dilated annulus, indicating that this dilatation was an important trigger of functional TR. Additionally, in the majority of patients with severe TR, "anterior displacement" of the tips of tricuspid leaflet(s) (6 mm or more from the tricuspid annulus towards the right ventricle) was observed, which was thought to be due to the chordal traction secondary to the right ventricular dilatation, and contributed to the development of functional TR by disturbing sufficient coaptation. In one particular case, severe TR was associated with " malaligned coaptation" caused by the anterior displacement confined to the septal leaflet, indicating that asymmetrical dilatation of the right ventricle and/or disorientation of chordae-valve system may contribute to TR.(ABSTRACT TRUNCATED AT 250 WORDS)

Altered lumbar spine structure, biochemistry and biomechanical properties in a canine model of mucopolysaccharidosis type VII

PubMed Central

Smith, Lachlan J; Martin, John T; Szczesny, Spencer E; Ponder, Katherine P; Haskins, Mark E; Elliott, Dawn M

2010-01-01

Mucopolysaccharidosis VII (MPS VII) is a lysosomal storage disorder characterized by a deficiency in β-glucuronidase activity, leading to systemic accumulation of poorly degraded glycosaminoglycans (GAG). Along with other morbidities, MPS VII is associated with paediatric spinal deformity. The objective of this study was to examine potential associations between abnormal lumbar spine matrix structure and composition in MPS VII, and spine segment and tissue-level mechanical properties, using a naturally occurring canine model with a similar clinical phenotype to the human form of the disorder. Segments from juvenile MPS VII and unaffected dogs were allocated to: radiography, gross morphology, histology, biochemistry, and mechanical testing. MPS VII spines had radiolucent lesions in the vertebral body epiphyses. Histologically, this corresponded to a GAG-rich cartilaginous region in place of bone, and elevated GAG staining was seen in the annulus fibrosus. Biochemically, MPS VII samples had elevated GAG in the outer annulus fibrosus and epiphyses, low calcium in the epiphyses, and high water content in all regions except the nucleus pulposus. MPS VII spine segments had higher range of motion and lower stiffness than controls. Endplate indentation stiffness and failure loads were significantly lower in MPS VII samples, while annulus fibrosus tensile mechanical properties were normal. Vertebral body lesions in MPS VII spines suggest a failure to convert cartilage to bone during development. Low stiffness in these regions likely contributes to mechanical weakness in motion segments and is a potential factor in the progression of spinal deformity. PMID:19918911

Operating and maintaining your heat recovery ventilator (HRV) -- Revised edition. Home heating and cooling series, Number 8

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

NONE

Heat recovery ventilators (HRVs) differ from other mechanical ventilation devices by their ability to exchange heat between supply and exhaust air streams, which reduces the cost of heating or cooling fresh air. This booklet discusses the need for mechanical ventilation in conventional and energy-efficient homes, an explains the components of a HRV system, how to operate and maintain the system, and how to solve operating problems. A maintenance chart and schedule and a HRV troubleshooting guide are included.

Theoretical flow regime diagrams for the AGCE

NASA Technical Reports Server (NTRS)

Fowlis, W. W.; Miller, T. L.; Roberts, G. O.; Kopecky, K. J.

1984-01-01

The major criterion for the design of the Atmospheric General Circulation Experiment is that it be possible to realize strong baroclinic instability in the apparatus. A spherical annulus configuration which allows only steady basic state flows was chosen for the first set of stability analyses. Baroclinic instability was found for this configuration and few results suggest a regime diagram very different from the cylindrical annulus regime diagram.

Restrictive annuloplasty to treat functional mitral regurgitation: optimize the restriction to improve the results?

PubMed

Totaro, Pasquale; Adragna, Nicola; Argano, Vincenzo

2008-03-01

Today, the 'gold standard' treatment of functional mitral regurgitation (MR) is the subject of much discussion. Although restrictive annuloplasty is currently considered the most reproducible technique, the means by which the degree of annular restriction is optimized remains problematic. The study was designed in order to identify whether the degree of restriction of the mitral annulus could influence early and midterm results following the treatment of functional MR using restrictive annuloplasty. A total of 32 consecutive patients with functional MR grade > or = 3+ was enrolled, among whom the mean anterior-posterior (AP) mitral annulus diameter was 39 +/- 3 mm. Restrictive mitral annuloplasty (combined with coronary artery bypass grafting) was performed in all patients using a Carpentier-Edwards Classic or Physio ring (size 26 or 28). The degree of AP annular restriction was calculated for each patient, and correlated with early and mid-term residual MR and left ventricular (LV) reverse remodeling (in terms of LV end-diastolic diameter (LVEDD) and LV end-diastolic volume (LVEDV) reduction). All surviving patients were examined at a one-year follow up. The mean AP mitral annulus restriction achieved was 48 +/- 4%. Intraoperatively, transesophageal echocardiography showed no residual MR in any patient. Before discharge from hospital, transthoracic echocardiography confirmed an absence of residual MR and showed significant LV reverse remodeling (LVEDV from 121 +/- 25 ml to 97 +/- 26 ml; LVEDD from 55 +/- 6 mm to 47 +/- 8 mm). A significant correlation (r = 0.57, p < 0.001) was identified between the degree of AP annulus restriction and LVEDV reduction. A cut-off of annular restriction of 40% (based on AP annulus measurement) correlated with a more significant reverse remodeling. The early postoperative data, with no recurrence of significant MR, was confirmed at a one-year follow up examination. A marked restriction of the AP mitral annulus diameter (> 40% of preoperative) appears to have a favorable influence on early postoperative LV reverse remodeling, and also allows for complete resolution of functional MR. In addition, 'no tolerance' of early residual MR seems to have a favorable influence on mid-term results, leading to a reduction in the one-year recurrence of significant MR.

Wide acceptance angle, high concentration ratio, optical collector

NASA Technical Reports Server (NTRS)

Kruer, Mark Arthur (Inventor)

1990-01-01

The invention is directed to an optical collector requiring a wide acceptance angle, and a high concentration ratio. The invention is particularly adapted for use in solar collectors of cassegrain design. The optical collector system includes a parabolic circular concave primary mirror and a hyperbolic circular convex secondary mirror. The primary mirror includes a circular hole located at its center wherein a solar collector is located. The mirrored surface of the secondary mirror has three distinct zones: a center circle, an on-axis annulus, and an off-axis section. The parabolic shape of the primary mirror is chosen so that the primary mirror reflects light entering the system on-axis onto the on-axis annulus. A substantial amount of light entering the system off-axis is reflected by the primary mirror onto either the off-axis section or onto the center circle. Subsequently, the off-axis sections reflect the off-axis light toward the solar collector. Thus, off-axis light is captured which would otherwise be lost to the system. The novelty of the system appears to lie in the configuration of the primary mirror which focuses off-axis light onto an annular portion of the secondary mirror to enable capture thereof. This feature results in wide acceptance angle and a high concentration ratio, and also compensates for the effects of non-specular reflection, and enables a cassegrain configuration to be used where such characteristics are required.

Electrosurgical Smoke: Ultrafine Particle Measurements and Work Environment Quality in Different Operating Theatres.

PubMed

Romano, Francesco; Gustén, Jan; De Antonellis, Stefano; Joppolo, Cesare M

2017-01-30

Air cleanliness in operating theatres (OTs) is an important factor for preserving the health of both the patient and the medical staff. Particle contamination in OTs depends mainly on the surgery process, ventilation principle, personnel clothing systems and working routines. In many open surgical operations, electrosurgical tools (ESTs) are used for tissue cauterization. ESTs generate a significant airborne contamination, as surgical smoke. Surgical smoke is a work environment quality problem. Ordinary surgical masks and OT ventilation systems are inadequate to control this problem. This research work is based on numerous monitoring campaigns of ultrafine particle concentrations in OTs, equipped with upward displacement ventilation or with a downward unidirectional airflow system. Measurements performed during ten real surgeries highlight that the use of ESTs generates a quite sharp and relevant increase of particle concentration in the surgical area as well within the entire OT area. The measured contamination level in the OTs are linked to surgical operation, ventilation principle, and ESTs used. A better knowledge of airborne contamination is crucial for limiting the personnel's exposure to surgical smoke. Research results highlight that downward unidirectional OTs can give better conditions for adequate ventilation and contaminant removal performances than OTs equipped with upward displacement ventilation systems.

Particle transport in low-energy ventilation systems. Part 2: Transients and experiments.

PubMed

Bolster, D T; Linden, P F

2009-04-01

Providing adequate indoor air quality while reducing energy consumption is a must for efficient ventilation system design. In this work, we study the transport of particulate contaminants in a displacement-ventilated space, using the idealized 'emptying filling box' model (P.F. Linden, G.F. Lane-serff and D.A. Smeed (1990) Emptying filling boxes: the fluid mechanics of natural ventilation, J. fluid Mech., 212, 309-335.). In this paper, we focused on transient contaminant transport by modeling three transient contamination scenarios, namely the so called 'step-up', 'step-down', and point source cases. Using analytical integral models and numerical models we studied the transient behavior of each of these three cases. We found that, on average, traditional and low-energy systems can be similar in overall pollutant removal efficiency, although quite different vertical gradients can exist. This plays an important role in estimating occupant exposure to contaminant. A series of laboratory experiments were conducted to validate the developed models. The results presented here illustrate that the source location plays a very important role in the distribution of contaminant concentration for spaces ventilated by low energy displacement-ventilation systems. With these results and the knowledge of typical contaminant sources for a given type of space practitioners can design or select more effective systems for the purpose at hand.

Procedures and Standards for Residential Ventilation System Commissioning: An Annotated Bibliography

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

Stratton, J. Chris; Wray, Craig P.

2013-04-01

Beginning with the 2008 version of Title 24, new homes in California must comply with ANSI/ASHRAE Standard 62.2-2007 requirements for residential ventilation. Where installed, the limited data available indicate that mechanical ventilation systems do not always perform optimally or even as many codes and forecasts predict. Commissioning such systems when they are installed or during subsequent building retrofits is a step towards eliminating deficiencies and optimizing the tradeoff between energy use and acceptable IAQ. Work funded by the California Energy Commission about a decade ago at Berkeley Lab documented procedures for residential commissioning, but did not focus on ventilation systems.more » Since then, standards and approaches for commissioning ventilation systems have been an active area of work in Europe. This report describes our efforts to collect new literature on commissioning procedures and to identify information that can be used to support the future development of residential-ventilation-specific procedures and standards. We recommend that a standardized commissioning process and a commissioning guide for practitioners be developed, along with a combined energy and IAQ benefit assessment standard and tool, and a diagnostic guide for estimating continuous pollutant emission rates of concern in residences (including a database that lists emission test data for commercially-available labeled products).« less

Effect of central ventilation and air conditioner system on the concentration and health risk from airborne polycyclic aromatic hydrocarbons.

PubMed

Lv, Jinze; Zhu, Lizhong

2013-03-01

Central ventilation and air conditioner systems are widely utilized nowadays in public places for air exchange and temperature control, which significantly influences the transfer of pollutants between indoors and outdoors. To study the effect of central ventilation and air conditioner systems on the concentration and health risk from airborne pollutants, a spatial and temporal survey was carried out using polycyclic aromatic hydrocarbons (PAHs) as agent pollutants. During the period when the central ventilation system operated without air conditioning (AC-off period), concentrations of 2-4 ring PAHs in the model supermarket were dominated by outdoor levels, due to the good linearity between indoor air and outdoor air (r(p) > 0.769, p < 0.05), and the slopes (1.2-4.54) indicated that ventilating like the model supermarket increased the potential health risks from low molecular weight PAHs. During the period when the central ventilation and air conditioner systems were working simultaneously (AC-on period), although the total levels of PAHs were increased, the concentrations and percentage of the particulate PAHs indoors declined significantly. The BaP equivalency (BaPeq) concentration indicated that utilization of air conditioning reduced the health risks from PAHs in the model supermarket.

Preoperational test report, recirculation ventilation systems

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

Clifton, F.T.

1997-11-11

This represents a preoperational test report for Recirculation Ventilation Systems, Project W-030. Project W-030 provides a ventilation upgrade for the four Aging Waste Facility tanks. The system provides vapor space cooling of tanks AY1O1, AY102, AZ1O1, AZ102 and supports the ability to exhaust air from each tank. Each system consists of a valved piping loop, a fan, condenser, and moisture separator; equipment is located inside each respective tank farm in its own hardened building. The tests verify correct system operation and correct indications displayed by the central Monitor and Control System.

Optimal ventilation of the anesthetized pediatric patient.

PubMed

Feldman, Jeffrey M

2015-01-01

Mechanical ventilation of the pediatric patient is challenging because small changes in delivered volume can be a significant fraction of the intended tidal volume. Anesthesia ventilators have traditionally been poorly suited to delivering small tidal volumes accurately, and pressure-controlled ventilation has become used commonly when caring for pediatric patients. Modern anesthesia ventilators are designed to deliver small volumes accurately to the patient's airway by compensating for the compliance of the breathing system and delivering tidal volume independent of fresh gas flow. These technology advances provide the opportunity to implement a lung-protective ventilation strategy in the operating room based upon control of tidal volume. This review will describe the capabilities of the modern anesthesia ventilator and the current understanding of lung-protective ventilation. An optimal approach to mechanical ventilation for the pediatric patient is described, emphasizing the importance of using bedside monitors to optimize the ventilation strategy for the individual patient.

Annular dynamics after mitral valve repair with different prosthetic rings: A real-time three-dimensional transesophageal echocardiography study.

PubMed

Nishi, Hiroyuki; Toda, Koichi; Miyagawa, Shigeru; Yoshikawa, Yasushi; Fukushima, Satsuki; Kawamura, Masashi; Yoshioka, Daisuke; Saito, Tetsuya; Ueno, Takayoshi; Kuratani, Toru; Sawa, Yoshiki

2016-09-01

We assessed the effects of different types of prosthetic rings on mitral annular dynamics using real-time three-dimensional echocardiography (RT3DE). RT3DE was performed in 44 patients, including patients undergoing mitral annuloplasty using the Cosgrove-Edwards flexible band (Group A, n = 10), the semi-rigid Sorin Memo 3D ring (Group B, n = 17), the semi-rigid Edwards Physio II ring (Group C, n = 7) and ten control subjects. Various annular diameters were measured throughout the cardiac cycle. We observed flexible anterior annulus motion in all of the groups except Group C. A flexible posterior annulus was only observed in Group B and the Control group. The mitral annular area changed during the cardiac cycle by 8.4 ± 3.2, 6.3 ± 2.0, 3.2 ± 1.3, and 11.6 ± 5.0 % in Group A, Group B, Group C, and the Control group, respectively. The dynamic diastolic to systolic change in mitral annular diameters was lost in Group C, while it was maintained in Group A, and to a good degree in Group B. In comparison to the Control group, the mitral annulus shape was more ellipsoid in Group B and Group C, and more circular in Group A. Although mitral regurgitation was well controlled by all of the types of rings that were utilized in the present study, we demonstrated that the annulus motion and annulus shape differed according to the type of prosthetic ring that was used, which might provide important information for the selection of an appropriate prosthetic ring.

Diagnostic Capability of Peripapillary Three-dimensional Retinal Nerve Fiber Layer Volume for Glaucoma Using Optical Coherence Tomography Volume Scans.

PubMed

Khoueir, Ziad; Jassim, Firas; Poon, Linda Yi-Chieh; Tsikata, Edem; Ben-David, Geulah S; Liu, Yingna; Shieh, Eric; Lee, Ramon; Guo, Rong; Papadogeorgou, Georgia; Braaf, Boy; Simavli, Huseyin; Que, Christian; Vakoc, Benjamin J; Bouma, Brett E; de Boer, Johannes F; Chen, Teresa C

2017-10-01

To determine the diagnostic capability of peripapillary 3-dimensional (3D) retinal nerve fiber layer (RNFL) volume measurements from spectral-domain optical coherence tomography (OCT) volume scans for open-angle glaucoma (OAG). Assessment of diagnostic accuracy. Setting: Academic clinical setting. Total of 180 patients (113 OAG and 67 normal subjects). One eye per subject was included. Peripapillary 3D RNFL volumes were calculated for global, quadrant, and sector regions, using 4 different-size annuli. Peripapillary 2D RNFL thickness circle scans were also obtained. Area under the receiver operating characteristic curve (AUROC) values, sensitivity, specificity, positive and negative predictive values, positive and negative likelihood ratios. Among all 2D and 3D RNFL parameters, best diagnostic capability was associated with inferior quadrant 3D RNFL volume of the smallest annulus (AUROC value 0.977). Otherwise, global 3D RNFL volume AUROC values were comparable to global 2D RNFL thickness AUROC values for all 4 annulus sizes (P values: .0593 to .6866). When comparing the 4 annulus sizes for global RNFL volume, the smallest annulus had the best AUROC values (P values: .0317 to .0380). The smallest-size annulus may have the best diagnostic potential, partly owing to having no areas excluded for being larger than the 6 × 6 mm 2 scanned region. Peripapillary 3D RNFL volume showed excellent diagnostic performance for detecting glaucoma. Peripapillary 3D RNFL volume parameters have the same or better diagnostic capability compared to peripapillary 2D RNFL thickness measurements, although differences were not statistically significant. Copyright © 2017 Elsevier Inc. All rights reserved.

An evaluation of the use of new Doppler methods for detecting longitudinal function abnormalities in a pacing-induced heart failure model

NASA Technical Reports Server (NTRS)

Tabata, Tomotsugu; Cardon, Lisa A.; Armstrong, Guy P.; Fukamach, Kiyotaka; Takagaki, Masami; Ochiai, Yoshie; McCarthy, Patrick M.; Thomas, James D.

2003-01-01

BACKGROUND: Doppler tissue echocardiography and color M-mode Doppler flow propagation velocity have proven useful in evaluating cross-sections of patients with left ventricular (LV) dysfunction, but experience with serial changes is limited. Purpose and methods: We tested their use by evaluating the temporal changes of LV function in a pacing-induced congestive heart failure model. Rapid ventricular pacing was initiated and maintained in 20 dogs for 4 weeks. Echocardiography was performed at baseline and weekly during brief pacing cessation. RESULTS: With rapid pacing, LV volume significantly increased and ejection fraction (57%-28%), stroke volume (37-18 mL), and mitral annulus systolic velocity (16.1-6.6 cm/s) by Doppler tissue echocardiography significantly decreased, with ejection fraction and mitral annulus systolic velocity closely correlated (r = 0.706, P <.0001). In contrast to the mitral inflow velocities, mitral annulus early diastolic velocity decreased steadily (12.3-7.3 cm/s) resulting in a dramatic decrease in mitral annulus early/late (1.22-0.57) diastolic velocity with no tendency toward pseudonormalization. The color M-mode Doppler flow propagation velocity also showed significant steady decrease (57-24 cm/s) throughout the pacing period. Multiple regression analysis chose mitral annulus systolic velocity (r = 0.895, P <.0001) and propagation velocity (r = 0.782, P <.0001) for the most important factor predicting LV systolic and diastolic function, respectively. CONCLUSIONS: Doppler tissue echocardiography and color M-mode Doppler flow could evaluate the serial deterioration in LV dysfunction throughout the pacing period. These were more useful in quantifying progressive LV dysfunction than conventional ehocardiographic techniques, and were probably relatively independent of preload. These techniques could be suitable for longitudinal evaluation in addition to the cross-sectional study.

3D echocardiographic analysis of aortic annulus for transcatheter aortic valve replacement using novel aortic valve quantification software: Comparison with computed tomography.

PubMed

Mediratta, Anuj; Addetia, Karima; Medvedofsky, Diego; Schneider, Robert J; Kruse, Eric; Shah, Atman P; Nathan, Sandeep; Paul, Jonathan D; Blair, John E; Ota, Takeyoshi; Balkhy, Husam H; Patel, Amit R; Mor-Avi, Victor; Lang, Roberto M

2017-05-01

With the increasing use of transcatheter aortic valve replacement (TAVR) in patients with aortic stenosis (AS), computed tomography (CT) remains the standard for annulus sizing. However, 3D transesophageal echocardiography (TEE) has been an alternative in patients with contraindications to CT. We sought to (1) test the feasibility, accuracy, and reproducibility of prototype 3DTEE analysis software (Philips) for aortic annular measurements and (2) compare the new approach to the existing echocardiographic techniques. We prospectively studied 52 patients who underwent gated contrast CT, procedural 3DTEE, and TAVR. 3DTEE images were analyzed using novel semi-automated software designed for 3D measurements of the aortic root, which uses multiplanar reconstruction, similar to CT analysis. Aortic annulus measurements included area, perimeter, and diameter calculations from these measurements. The results were compared to CT-derived values. Additionally, 3D echocardiographic measurements (3D planimetry and mitral valve analysis software adapted for the aortic valve) were also compared to the CT reference values. 3DTEE image quality was sufficient in 90% of patients for aortic annulus measurements using the new software, which were in good agreement with CT (r-values: .89-.91) and small (<4%) inter-modality nonsignificant biases. Repeated measurements showed <10% measurements variability. The new 3D analysis was the more accurate and reproducible of the existing echocardiographic techniques. Novel semi-automated 3DTEE analysis software can accurately measure aortic annulus in patients with severe AS undergoing TAVR, in better agreement with CT than the existing methodology. Accordingly, intra-procedural TEE could potentially replace CT in patients where CT carries significant risk. © 2017, Wiley Periodicals, Inc.

Long-Term Heating to Improve Receiver Performance

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

Glatzmaier, Greg C.; Cable, Robert; Newmarker, Marc

The buildup of hydrogen in the heat transfer fluid (HTF) that circulates through components of parabolic trough power plants decreases receiver thermal efficiency, and ultimately, it decreases plant performance and electricity output. The generation and occurrence of hydrogen in the HTF provides the driving force for hydrogen to permeate from the HTF through the absorber tube wall and into the receiver annulus. Getters adsorb hydrogen from the annulus volume until they saturate and are no longer able to maintain low hydrogen pressure. The increase in hydrogen pressure within the annulus significantly degrades thermal performance of the receiver and decreases overallmore » power-plant efficiency. NREL and Acciona Energy North America (Acciona) are developing a method to control the levels of dissolved hydrogen in the circulating HTF. The basic approach is to remove hydrogen from the expansion tanks of the HTF subsystem at a rate that maintains hydrogen in the circulating HTF to a target level. Full-plant steady-state models developed by the National Renewable Energy Laboratory (NREL) predict that if hydrogen is removed from the HTF within the expansion tanks, the HTF that circulates through the collector field remains essentially free of hydrogen until the HTF returns to the power block in the hot headers. One of the key findings of our modeling is the prediction that hydrogen will reverse-permeate out of the receiver annulus if dissolved hydrogen in the HTF is kept sufficiently low. To test this prediction, we performed extended heating of an in-service receiver that initially had high levels of hydrogen in its annulus. The heating was performed using NREL's receiver test stand. Results of our testing showed that receiver heat loss steadily decreased with daily heating, resulting in a corresponding improvement in receiver thermal efficiency.« less

The effect of postural changes (leg lifting) on tissue Doppler parameters in coronary artery disease.

PubMed

Pirat, Bahar; Yildirir, Aylin; Simşek, Vahide; Ozin, Bülent; Müderrisoğlu, Haldun

2008-03-01

We investigated the effect of increased preload through postural changes (leg lifting) on tissue Doppler parameters in patients with and without coronary artery disease (CAD). The study included 42 patients who were scheduled for coronary angiography. All the patients underwent standard two-dimensional, color Doppler and tissue Doppler echocardiography before coronary angiography. Tissue Doppler imaging was performed from septal and lateral mitral annuluses at baseline and during 45 degrees leg lifting followed by two-minute stabilization. Patients were grouped based on coronary angiography findings: those having stenosis greater than 70% were considered to have CAD and those with normal coronary arteries comprised the control group. Echocardiography measurements were compared between the two groups. Angiography showed normal coronary arteries or border irregularities in 22 patients and CAD in 20 patients. The two groups were similar with regard to demographic data and ejection fractions, except for male preponderance in the CAD group. Compared with the control group, patients with CAD exhibited a significantly lower isovolumic acceleration rate (IVA) at the lateral (p=0.007) and septal (p=0.03) mitral annuluses. In the control group, leg lifting resulted in increased systolic velocity (S) compared with baseline at the lateral (p=0.009) and septal (p=0.01) annuluses, whereas S wave augmentation was only significant at the septal annulus (p=0.009) in patients with CAD. No significant change was observed in IVA following leg lifting in both groups. Preload alteration induced by leg lifting resulted in similar changes in tissue Doppler parameters in patients with and without CAD, except for blunted augmentation of S wave at the lateral annulus in CAD. Detection of decreased IVA at baseline may be a useful finding for CAD.

In vitro and in silico investigations of disc nucleus replacement

PubMed Central

Reitmaier, Sandra; Shirazi-Adl, Aboulfazl; Bashkuev, Maxim; Wilke, Hans-Joachim; Gloria, Antonio; Schmidt, Hendrik

2012-01-01

Currently, numerous hydrogels are under examination as potential nucleus replacements. The clinical success, however, depends on how well the mechanical function of the host structure is restored. This study aimed to evaluate the extent to and mechanisms by which surgery for nucleus replacements influence the mechanical behaviour of the disc. The effects of an annulus defect with and without nucleus replacement on disc height and nucleus pressure were measured using 24 ovine motion segments. The following cases were considered: intact; annulus incision repaired by suture and glue; annulus incision with removal and re-implantation of nucleus tissue repaired by suture and glue or plug. To identify the likely mechanisms observed in vitro, a finite-element model of a human disc (L4–L5) was employed. Both studies were subjected to physiological cycles of compression and recovery. A repaired annulus defect did not influence the disc behaviour in vitro, whereas additional nucleus removal and replacement substantially decreased disc stiffness and nucleus pressure. Model predictions demonstrated the substantial effects of reductions in replaced nucleus water content, bulk modulus and osmotic potential on disc height loss and pressure, similar to measurements. In these events, the compression load transfer in the disc markedly altered by substantially increasing the load on the annulus when compared with the nucleus. The success of hydrogels for nucleus replacements is not only dependent on the implant material itself but also on the restoration of the environment perturbed during surgery. The substantial effects on the disc response of disruptions owing to nucleus replacements can be simulated by reduced nucleus water content, elastic modulus and osmotic potential. PMID:22337630

A new prototype of an electronic jet-ventilator and its humidification system

PubMed Central

Kraincuk, Paul; Kepka, Anton; Ihra, Gerald; Schabernig, Christa; Aloy, Alexander

1999-01-01

Background: Adequate humidification in long-term jet ventilation is a critical aspect in terms of clinical safety. Aim: To assess a prototype of an electronic jet-ventilator and its humidification system. Methods: Forty patients with respiratory insufficiency were randomly allocated to one of four groups. The criterion for inclusion in this study was respiratory insufficiency exhibiting a Murray score above 2. The four groups of patients were ventilated with three different respirators and four different humidification systems. Patients in groups A and B received superimposed high-frequency jet ventilation (SHFJV) by an electronic jet-ventilator either with (group A) or without (group B) an additional humidification system. Patients in group C received high-frequency percussive ventilation (HFPV) by a pneumatic high-frequency respirator, using a hot water humidifier for warming and moistening the inspiration gas. Patients in group D received conventional mechanical ventilation using a standard intensive care unit respirator with a standard humidification system. SHFJV and HFPV were used for a period of 100 h (4days). Results: A significantly low inspiration gas temperature was noted in patients in group B, initially (27.2 ± 2.5°C) and after 2 days (28.0 ± 1.6°C) (P < 0.05). The percentage of relative humidity of the inspiration gas in patients in group B was also initially significantly low (69.8 ± 4.1%; P < 0.05) but rose to an average of 98 ± 2.8% after 2 h. The average percentage across all four groups amounted to 98 ± 0.4% after 2 h. Inflammation of the tracheal mucosa was found in patients in group B and the mucosal injury score (MIS) was significantly higher than in all the other groups. Patients in groups A, C and D showed no severe evidence of airway damage, exhibiting adequate values of relative humidity and temperature of the inspired gas. Conclusion: The problems of humidification associated with jet ventilation can be fully prevented by using this new jet-ventilator. These data were sustained by nondeteriorating MIS values at the end of the 4-day study period in groups A, C and D. PMID:11056732

Enhancing Safety of Artificially Ventilated Patients Using Ambient Process Analysis.

PubMed

Lins, Christian; Gerka, Alexander; Lüpkes, Christian; Röhrig, Rainer; Hein, Andreas

2018-01-01

In this paper, we present an approach for enhancing the safety of artificially ventilated patients using ambient process analysis. We propose to use an analysis system consisting of low-cost ambient sensors such as power sensor, RGB-D sensor, passage detector, and matrix infrared temperature sensor to reduce risks for artificially ventilated patients in both home and clinical environments. We describe the system concept and our implementation and show how the system can contribute to patient safety.

Utilizing a Suited Manikin Test Apparatus and Spacesuit Ventilation Loop to Evaluate Carbon Dioxide Washout

NASA Technical Reports Server (NTRS)

Chullen, Cinda; Conger, Bruce; Korona, Adam; Kanne, Bryan; McMillin, Summer; Norcross, Jason; Jeng, Frank; Swickrath, Mike

2014-01-01

NASA is pursuing technology development of an Advanced Extravehicular Mobility Unit (AEMU) which is an integrated assembly made up of primarily a pressure garment system and a Portable Life Support System (PLSS). The PLSS is further composed of an oxygen subsystem, a ventilation subsystem, and a thermal subsystem. One of the key functions of the ventilation system is to remove and control the carbon dioxide delivered to the crewmember. Carbon dioxide washout is the mechanism by which CO2 levels are controlled within the spacesuit helmet to limit the concentration of CO2 inhaled by the crew member. CO2 washout performance is a critical parameter needed to ensure proper and robust designs that are insensitive to human variabilities in a spacesuit. A Suited Manikin Test Apparatus (SMTA) is being developed to augment testing of the PLSS ventilation loop in order to provide a lower cost and more controlled alternative to human testing. The CO2 removal function is performed by the regenerative Rapid Cycle Amine (RCA) within the PLSS ventilation loop and its performance is evaluated within the integrated SMTA and Ventilation Loop test system. This paper will provide a detailed description of the schematics, test configurations, and hardware components of this integrated system. Results and analysis of testing performed with this integrated system will be presented within this paper.

Variable versus conventional lung protective mechanical ventilation during open abdominal surgery: study protocol for a randomized controlled trial.

PubMed

Spieth, Peter M; Güldner, Andreas; Uhlig, Christopher; Bluth, Thomas; Kiss, Thomas; Schultz, Marcus J; Pelosi, Paolo; Koch, Thea; Gama de Abreu, Marcelo

2014-05-02

General anesthesia usually requires mechanical ventilation, which is traditionally accomplished with constant tidal volumes in volume- or pressure-controlled modes. Experimental studies suggest that the use of variable tidal volumes (variable ventilation) recruits lung tissue, improves pulmonary function and reduces systemic inflammatory response. However, it is currently not known whether patients undergoing open abdominal surgery might benefit from intraoperative variable ventilation. The PROtective VARiable ventilation trial ('PROVAR') is a single center, randomized controlled trial enrolling 50 patients who are planning for open abdominal surgery expected to last longer than 3 hours. PROVAR compares conventional (non-variable) lung protective ventilation (CV) with variable lung protective ventilation (VV) regarding pulmonary function and inflammatory response. The primary endpoint of the study is the forced vital capacity on the first postoperative day. Secondary endpoints include further lung function tests, plasma cytokine levels, spatial distribution of ventilation assessed by means of electrical impedance tomography and postoperative pulmonary complications. We hypothesize that VV improves lung function and reduces systemic inflammatory response compared to CV in patients receiving mechanical ventilation during general anesthesia for open abdominal surgery longer than 3 hours. PROVAR is the first randomized controlled trial aiming at intra- and postoperative effects of VV on lung function. This study may help to define the role of VV during general anesthesia requiring mechanical ventilation. Clinicaltrials.gov NCT01683578 (registered on September 3 3012).

A GIS-based approach: Influence of the ventilation layout to the environmental conditions in an underground mine.

PubMed

Bascompta, Marc; Castañón, Ana María; Sanmiquel, Lluís; Oliva, Josep

2016-11-01

Gases such as CO, CO2 or NOx are constantly generated by the equipment in any underground mine and the ventilation layout can play an important role in keeping low concentrations in the working faces. Hence, a method able to control the workplace environment is crucial. This paper proposes a geographical information system (GIS) for such goal. The system created provides the necessary tools to manage and analyse an underground environment, connecting pollutants and temperatures with the ventilation characteristics over time. Data concerning the ventilation system, in a case study, has been taken every month since 2009 and integrated into the management system, which has quantified the gasses concentration throughout the mine due to the characteristics and evolution of the ventilation layout. Three different zones concerning CO, CO2, NOx and effective temperature have been found as well as some variations among workplaces within the same zone that suggest local airflow recirculations. The system proposed could be a useful tool to improve the workplace conditions and efficiency levels. Copyright © 2016 Elsevier Ltd. All rights reserved.

HOW THE LEED VENTILATION CREDIT IMPACTS ENERGY CONSUMPTION OF GSHP SYSTEMS A CASE STUDY FOR PRIMARY SCHOOLS

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

Liu, Xiaobing

2011-01-01

This paper presents a study on the impacts of increased outdoor air (OA) ventilation on the performance of ground-source heat pump (GSHP) systems that heat and cool typical primary schools. Four locations Phoenix, Miami, Seattle, and Chicago are selected in this study to represent different climate zones in the United States. eQUEST, an integrated building and HVAC system energy analysis program, is used to simulate a typical primary school and the GSHP system at the four locations with minimum and 30% more than minimum OA ventilation. The simulation results show that, without an energy recovery ventilator, the 30% more OAmore » ventilation results in an 8.0 13.3% increase in total GSHP system energy consumption at the four locations. The peak heating and cooling loads increase by 20.2 30% and 14.9 18.4%, respectively, at the four locations. The load imbalance of the ground heat exchanger is increased in hot climates but reduced in mild and cold climates.« less

THE EFFECT OF A TWISTED MAGNETIC FIELD ON THE PERIOD RATIO P{sub 1}/P{sub 2} OF NONAXISYMMETRIC MAGNETOHYDRODYNAMIC WAVES

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

Karami, K.; Bahari, K., E-mail: KKarami@uok.ac.ir, E-mail: K.Bahari@razi.ac.ir

2012-10-01

We consider nonaxisymmetric magnetohydrodynamic (MHD) modes in a zero-beta cylindrical compressible thin magnetic flux tube modeled as a twisted core surrounded by a magnetically twisted annulus, with both embedded in a straight ambient external field. The dispersion relation is derived and solved analytically and numerically to obtain the frequencies of the nonaxisymmetric MHD waves. The main result is that the twisted magnetic annulus does affect the period ratio P{sub 1}/P{sub 2} of the kink modes. For the kink modes, the magnetic twist in the annulus region can achieve deviations from P{sub 1}/P{sub 2} = 2 of the same order ofmore » magnitude as in the observations. Furthermore, the effect of the internal twist on the fluting modes is investigated.« less

Ventilator-Related Adverse Events: A Taxonomy and Findings From 3 Incident Reporting Systems.

PubMed

Pham, Julius Cuong; Williams, Tamara L; Sparnon, Erin M; Cillie, Tam K; Scharen, Hilda F; Marella, William M

2016-05-01

In 2009, researchers from Johns Hopkins University's Armstrong Institute for Patient Safety and Quality; public agencies, including the FDA; and private partners, including the Emergency Care Research Institute and the University HealthSystem Consortium (UHC) Safety Intelligence Patient Safety Organization, sought to form a public-private partnership for the promotion of patient safety (P5S) to advance patient safety through voluntary partnerships. The study objective was to test the concept of the P5S to advance our understanding of safety issues related to ventilator events, to develop a common classification system for categorizing adverse events related to mechanical ventilators, and to perform a comparison of adverse events across different adverse event reporting systems. We performed a cross-sectional analysis of ventilator-related adverse events reported in 2012 from the following incident reporting systems: the Pennsylvania Patient Safety Authority's Patient Safety Reporting System, UHC's Safety Intelligence Patient Safety Organization database, and the FDA's Manufacturer and User Facility Device Experience database. Once each organization had its dataset of ventilator-related adverse events, reviewers read the narrative descriptions of each event and classified it according to the developed common taxonomy. A Pennsylvania Patient Safety Authority, FDA, and UHC search provided 252, 274, and 700 relevant reports, respectively. The 3 event types most commonly reported to the UHC and the Pennsylvania Patient Safety Authority's Patient Safety Reporting System databases were airway/breathing circuit issue, human factor issues, and ventilator malfunction events. The top 3 event types reported to the FDA were ventilator malfunction, power source issue, and alarm failure. Overall, we found that (1) through the development of a common taxonomy, adverse events from 3 reporting systems can be evaluated, (2) the types of events reported in each database were related to the purpose of the database and the source of the reports, resulting in significant differences in reported event categories across the 3 systems, and (3) a public-private collaboration for investigating ventilator-related adverse events under the P5S model is feasible. Copyright © 2016 by Daedalus Enterprises.

32 CFR 644.450 - Items excluded from usual restoration obligation.

Code of Federal Regulations, 2014 CFR

2014-07-01

..., ventilators, and metal ceilings. (8) Structural steel or iron. (9) Fire escapes. (10) Heating systems. (11) Plumbing systems. (12) Ventilating systems and air conditioning systems. (13) Power plants. (14) Electric wiring. (15) Lighting fixtures (or replacement). (16) Sprinkler systems. (f) Settling or subsidence. (g...

32 CFR 644.450 - Items excluded from usual restoration obligation.

Code of Federal Regulations, 2012 CFR

2012-07-01

..., ventilators, and metal ceilings. (8) Structural steel or iron. (9) Fire escapes. (10) Heating systems. (11) Plumbing systems. (12) Ventilating systems and air conditioning systems. (13) Power plants. (14) Electric wiring. (15) Lighting fixtures (or replacement). (16) Sprinkler systems. (f) Settling or subsidence. (g...

32 CFR 644.450 - Items excluded from usual restoration obligation.

Code of Federal Regulations, 2013 CFR

2013-07-01

..., ventilators, and metal ceilings. (8) Structural steel or iron. (9) Fire escapes. (10) Heating systems. (11) Plumbing systems. (12) Ventilating systems and air conditioning systems. (13) Power plants. (14) Electric wiring. (15) Lighting fixtures (or replacement). (16) Sprinkler systems. (f) Settling or subsidence. (g...

Ventilation Transport Trade Study for Future Space Suit Life Support Systems

NASA Technical Reports Server (NTRS)

Kempf, Robert; Vogel, Matthew; Paul, Heather L.

2008-01-01

A new and advanced portable life support system (PLSS) for space suit surface exploration will require a durable, compact, and energy efficient system to transport the ventilation stream through the space suit. Current space suits used by NASA circulate the ventilation stream via a ball-bearing supported centrifugal fan. As NASA enters the design phase for the next generation PLSS, it is necessary to evaluate available technologies to determine what improvements can be made in mass, volume, power, and reliability for a ventilation transport system. Several air movement devices already designed for commercial, military, and space applications are optimized in these areas and could be adapted for EVA use. This paper summarizes the efforts to identify and compare the latest fan and bearing technologies to determine candidates for the next generation PLSS.

Investigation of the Cognitive Structures of Prospective Preschool Teachers on the Concepts of Circle, Disk and Annulus with the Word Association Test

ERIC Educational Resources Information Center

Gok Colak, Feride; Tugluk, Mehmet Nur

2017-01-01

This study aimed to investigate the cognitive structures of prospective preschool teachers and to identify their misconceptions about the concepts of circle, disk and annulus. In the study, the Word Association Test was used as the data collection instrument. The study was conducted in the fall semester of the 2014-2015 academic year with the…

Localized strain measurements of the intervertebral disc annulus during biaxial tensile testing.

PubMed

Karakolis, Thomas; Callaghan, Jack P

2015-01-01

Both inter-lamellar and intra-lamellar failures of the annulus have been described as potential modes of disc herniation. Attempts to characterize initial lamellar failure of the annulus have involved tensile testing of small tissue samples. The purpose of this study was to evaluate a method of measuring local surface strains through image analysis of a tensile test conducted on an isolated sample of annular tissue in order to enhance future studies of intervertebral disc failure. An annulus tissue sample was biaxial strained to 10%. High-resolution images captured the tissue surface throughout testing. Three test conditions were evaluated: submerged, non-submerged and marker. Surface strains were calculated for the two non-marker conditions based on motion of virtual tracking points. Tracking algorithm parameters (grid resolution and template size) were varied to determine the effect on estimated strains. Accuracy of point tracking was assessed through a comparison of the non-marker conditions to a condition involving markers placed on tissue surface. Grid resolution had a larger effect on local strain than template size. Average local strain error ranged from 3% to 9.25% and 0.1% to 2.0%, for the non-submerged and submerged conditions, respectively. Local strain estimation has a relatively high potential for error. Submerging the tissue provided superior strain estimates.

Multiple pure tone noise prediction

NASA Astrophysics Data System (ADS)

Han, Fei; Sharma, Anupam; Paliath, Umesh; Shieh, Chingwei

2014-12-01

This paper presents a fully numerical method for predicting multiple pure tones, also known as “Buzzsaw” noise. It consists of three steps that account for noise source generation, nonlinear acoustic propagation with hard as well as lined walls inside the nacelle, and linear acoustic propagation outside the engine. Noise generation is modeled by steady, part-annulus computational fluid dynamics (CFD) simulations. A linear superposition algorithm is used to construct full-annulus shock/pressure pattern just upstream of the fan from part-annulus CFD results. Nonlinear wave propagation is carried out inside the duct using a pseudo-two-dimensional solution of Burgers' equation. Scattering from nacelle lip as well as radiation to farfield is performed using the commercial solver ACTRAN/TM. The proposed prediction process is verified by comparing against full-annulus CFD simulations as well as against static engine test data for a typical high bypass ratio aircraft engine with hardwall as well as lined inlets. Comparisons are drawn against nacelle unsteady pressure transducer measurements at two axial locations as well as against near- and far-field microphone array measurements outside the duct. This is the first fully numerical approach (no experimental or empirical input is required) to predict multiple pure tone noise generation, in-duct propagation and far-field radiation. It uses measured blade coordinates to calculate MPT noise.

Numerical investigation of the onset of centrifugal buoyancy in a rotating cavity

NASA Astrophysics Data System (ADS)

Pitz, Diogo B.; Marxen, Olaf; Chew, John

2016-11-01

Buoyancy-induced flows in a differentially heated rotating annulus present a multitude of dynamics when control parameters such as rotation rate, temperature difference and Prandtl number are varied. Whilst most of the work in this area has been motivated by applications involving geophysics, the problem of buoyancy-induced convection in rotating systems is also relevant in industrial applications such as the flow between rotating disks of turbomachinery internal air systems, in which buoyancy plays a major role and poses a challenge to accurately predict temperature distributions and heat transfer rates. In such applications the rotational speeds involved are very large, so that the centrifugal accelerations induced are much higher than gravity. In this work we perform direct numerical simulations and linear stability analysis of flow induced by centrifugal buoyancy in a sealed rotating annulus of finite gap with flat end-walls, using a canonical setup representative of an internal air system rotating cavity. The analysis focuses on the behaviour of small-amplitude disturbances added to the base flow, and how those affect the onset of Rossby waves and, ultimately, the transition to a fully turbulent state where convection columns no longer have a well-defined structure. Diogo B. Pitz acknowledges the financial support from the Capes foundation through the Science without Borders program.

Ventilation and infiltration in high-rise apartment buildings

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

Diamond, R.C.; Feustel, H.E.; Dickerhoff, D.J.

1996-03-01

Air flow, air leakage measurements and numerical simulations were made on a 13-story apartment building to characterize the ventilation rates for the individual apartments. Parametric simulations were performed for specific conditions, e.g., height, orientation, outside temperature and wind speed. Our analysis of the air flow simulations suggest that the ventilation to the individual units varies considerably. With the mechanical ventilation system disabled and no wind, units at the lower level of the building have adequate ventilation only on days with high temperature differences, while units on higher floors have no ventilation at all. Units facing the windward side will bemore » over-ventilated when the building experiences wind directions between west and north. At the same time, leeward apartments did not experience any fresh air-because, in these cases, air flows enter the apartments from the corridor and exit through the exhaust shafts and the cracks in the facade. Even with the mechanical ventilation system operating, we found wide variation in the air flows to the individual apartments. In addition to the specific case presented here, these findings have more general implications for energy retrofits and health and comfort of occupants in high-rise apartment buildings.« less

Highlighting the importance of transitional ventilation regimes in the management of Mediterranean show caves (Nerja-Pintada system, southern Spain).

PubMed

Liñán, C; Del Rosal, Y; Carrasco, F; Vadillo, I; Benavente, J; Ojeda, L

2018-08-01

This study shows the utilization of the air CO 2 exhaled by a very high number of visitors in the Nerja Cave as both a tracer and an additional tool to precisely evaluate the air circulation through the entire karst system, which includes non-touristic passages, originally free of anthropogenic CO 2 . The analysis of the temporal - spatial evolution of the CO 2 content and other monitoring data measured from January 2015 to December 2016 in the Nerja-Pintada system, including air microbiological controls, has allowed us to define a new general ventilation model, of great interest for the conservation of the subterranean environment. During the annual cycle four different ventilation regimes and two ventilation modes (UAF-mode and DAF-mode) exist which determine the significance of the anthropogenic impact within the caves. During the winter regime, the strong ventilation regime and the airflow directions from the lowest to the highest entrance (UAF-mode) contribute to the rapid elimination of anthropogenic CO 2 , and this affects the whole karstic system. During the summer regime the DAF-mode ventilation (with airflows from the highest to the lowest entrances) is activated. Although the number of visitors is maximum and the natural ventilation of the karstic system is the lowest of the annual cycle, the anthropogenic impact only affects the Tourist Galleries. The transitional ventilation regimes -spring and autumn- are the most complex of the annual cycle, with changing air-flow directions (from UAF-mode to DAF-mode and vice versa) at diurnal and poly diurnal scale, which conditions the range of the anthropogenic impact in each sector of the karst system. The activation of the DAF-mode has been observed when the temperature difference between the external and air cave is higher than 5°C. Copyright © 2018 Elsevier B.V. All rights reserved.

Improving Patient Safety with X-Ray and Anesthesia Machine Ventilator Synchronization: A Medical Device Interoperability Case Study

NASA Astrophysics Data System (ADS)

Arney, David; Goldman, Julian M.; Whitehead, Susan F.; Lee, Insup

When a x-ray image is needed during surgery, clinicians may stop the anesthesia machine ventilator while the exposure is made. If the ventilator is not restarted promptly, the patient may experience severe complications. This paper explores the interconnection of a ventilator and simulated x-ray into a prototype plug-and-play medical device system. This work assists ongoing interoperability framework development standards efforts to develop functional and non-functional requirements and illustrates the potential patient safety benefits of interoperable medical device systems by implementing a solution to a clinical use case requiring interoperability.

TH-E-BRF-02: 4D-CT Ventilation Image-Based IMRT Plans Are Dosimetrically Comparable to SPECT Ventilation Image-Based Plans

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

Kida, S; University of Tokyo Hospital, Bunkyo, Tokyo; Bal, M

Purpose: An emerging lung ventilation imaging method based on 4D-CT can be used in radiotherapy to selectively avoid irradiating highly-functional lung regions, which may reduce pulmonary toxicity. Efforts to validate 4DCT ventilation imaging have been focused on comparison with other imaging modalities including SPECT and xenon CT. The purpose of this study was to compare 4D-CT ventilation image-based functional IMRT plans with SPECT ventilation image-based plans as reference. Methods: 4D-CT and SPECT ventilation scans were acquired for five thoracic cancer patients in an IRB-approved prospective clinical trial. The ventilation images were created by quantitative analysis of regional volume changes (amore » surrogate for ventilation) using deformable image registration of the 4D-CT images. A pair of 4D-CT ventilation and SPECT ventilation image-based IMRT plans was created for each patient. Regional ventilation information was incorporated into lung dose-volume objectives for IMRT optimization by assigning different weights on a voxel-by-voxel basis. The objectives and constraints of the other structures in the plan were kept identical. The differences in the dose-volume metrics have been evaluated and tested by a paired t-test. SPECT ventilation was used to calculate the lung functional dose-volume metrics (i.e., mean dose, V20 and effective dose) for both 4D-CT ventilation image-based and SPECT ventilation image-based plans. Results: Overall there were no statistically significant differences in any dose-volume metrics between the 4D-CT and SPECT ventilation imagebased plans. For example, the average functional mean lung dose of the 4D-CT plans was 26.1±9.15 (Gy), which was comparable to 25.2±8.60 (Gy) of the SPECT plans (p = 0.89). For other critical organs and PTV, nonsignificant differences were found as well. Conclusion: This study has demonstrated that 4D-CT ventilation image-based functional IMRT plans are dosimetrically comparable to SPECT ventilation image-based plans, providing evidence to use 4D-CT ventilation imaging for clinical applications. Supported in part by Free to Breathe Young Investigator Research Grant and NIH/NCI R01 CA 093626. The authors thank Philips Radiation Oncology Systems for the Pinnacle3 treatment planning systems.« less

46 CFR 111.33-9 - Ventilation exhaust.

Code of Federal Regulations, 2010 CFR

2010-10-01

... REQUIREMENTS Power Semiconductor Rectifier Systems § 111.33-9 Ventilation exhaust. The exhaust of each forced-air semiconductor rectifier system must: (a) Terminate in a location other than a hazardous location...

Convection driven zonal flows and vortices in the major planets.

PubMed

Busse, F. H.

1994-06-01

The dynamical properties of convection in rotating cylindrical annuli and spherical shells are reviewed. Simple theoretical models and experimental simulations of planetary convection through the use of the centrifugal force in the laboratory are emphasized. The model of columnar convection in a cylindrical annulus not only serves as a guide to the dynamical properties of convection in rotating sphere; it also is of interest as a basic physical system that exhibits several dynamical properties in their most simple form. The generation of zonal mean flows is discussed in some detail and examples of recent numerical computations are presented. The exploration of the parameter space for the annulus model is not yet complete and the theoretical exploration of convection in rotating spheres is still in the beginning phase. Quantitative comparisons with the observations of the dynamics of planetary atmospheres will have to await the consideration in the models of the effects of magnetic fields and the deviations from the Boussinesq approximation.

Exact sum rules for inhomogeneous drums

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

Amore, Paolo, E-mail: paolo.amore@gmail.com

2013-09-15

We derive general expressions for the sum rules of the eigenvalues of drums of arbitrary shape and arbitrary density, obeying different boundary conditions. The formulas that we present are a generalization of the analogous formulas for one dimensional inhomogeneous systems that we have obtained in a previous paper. We also discuss the extension of these formulas to higher dimensions. We show that in the special case of a density depending only on one variable the sum rules of any integer order can be expressed in terms of a single series. As an application of our result we derive exact summore » rules for the homogeneous circular annulus with different boundary conditions, for a homogeneous circular sector and for a radially inhomogeneous circular annulus with Dirichlet boundary conditions. -- Highlights: •We derive an explicit expression for the sum rules of inhomogeneous drums. •We discuss the extension to higher dimensions. •We discuss the special case of an inhomogeneity only along one direction.« less

Adjustable Pitot Probe

NASA Technical Reports Server (NTRS)

Ashby, George C., Jr.; Robbins, W. Eugene; Horsley, Lewis A.

1991-01-01

Probe readily positionable in core of uniform flow in hypersonic wind tunnel. Formed of pair of mating cylindrical housings: transducer housing and pitot-tube housing. Pitot tube supported by adjustable wedge fairing attached to top of pitot-tube housing with semicircular foot. Probe adjusted both radially and circumferentially. In addition, pressure-sensing transducer cooled internally by water or other cooling fluid passing through annulus of cooling system.

Adaptive support ventilation: State of the art review

PubMed Central

Fernández, Jaime; Miguelena, Dayra; Mulett, Hernando; Godoy, Javier; Martinón-Torres, Federico

2013-01-01

Mechanical ventilation is one of the most commonly applied interventions in intensive care units. Despite its life-saving role, it can be a risky procedure for the patient if not applied appropriately. To decrease risks, new ventilator modes continue to be developed in an attempt to improve patient outcomes. Advances in ventilator modes include closed-loop systems that facilitate ventilator manipulation of variables based on measured respiratory parameters. Adaptive support ventilation (ASV) is a positive pressure mode of mechanical ventilation that is closed-loop controlled, and automatically adjust based on the patient's requirements. In order to deliver safe and appropriate patient care, clinicians need to achieve a thorough understanding of this mode, including its effects on underlying respiratory mechanics. This article will discuss ASV while emphasizing appropriate ventilator settings, their advantages and disadvantages, their particular effects on oxygenation and ventilation, and the monitoring priorities for clinicians. PMID:23833471

Assessment of the impact of dipped guideways on urban rail transit systems: Ventilation and safety requirements

NASA Technical Reports Server (NTRS)

1982-01-01

The ventilation and fire safety requirements for subway tunnels with dipped profiles between stations as compared to subway tunnels with level profiles were evaluated. This evaluation is based upon computer simulations of a train fire emergency condition. Each of the tunnel configurations evaluated was developed from characteristics that are representative of modern transit systems. The results of the study indicate that: (1) The level tunnel system required about 10% more station cooling than dipped tunnel systems in order to meet design requirements; and (2) The emergency ventilation requirements are greater with dipped tunnel systems than with level tunnel systems.

Disruption of biomineralization pathways in spinal tissues of a mouse model of diffuse idiopathic skeletal hyperostosis.

PubMed

Ii, Hisataka; Warraich, Sumeeta; Tenn, Neil; Quinonez, Diana; Holdsworth, David W; Hammond, James R; Dixon, S Jeffrey; Séguin, Cheryle A

2016-09-01

Equilibrative nucleoside transporter 1 (ENT1) mediates passage of adenosine across the plasma membrane. We reported previously that mice lacking ENT1 (ENT1(-/-)) exhibit progressive ectopic mineralization of spinal tissues resembling diffuse idiopathic skeletal hyperostosis (DISH) in humans. Here, we investigated mechanisms underlying aberrant mineralization in ENT1(-/-) mice. Micro-CT revealed ectopic mineralization of spinal tissues in both male and female ENT1(-/-) mice, involving the annulus fibrosus of the intervertebral discs (IVDs) of older mice. IVDs were isolated from wild-type and ENT1(-/-) mice at 2months of age (prior to disc mineralization), 4, and 6months of age (disc mineralization present) and processed for real-time PCR, cell isolation, or histology. Relative to the expression of ENTs in other tissues, ENT1 was the primary nucleoside transporter expressed in wild-type IVDs and mediated the functional uptake of [(3)H]2-chloroadenosine by annulus fibrosus cells. No differences in candidate gene expression were detected in IVDs from ENT1(-/-) and wild-type mice at 2 or 4months of age. However, at 6months of age, expression of genes that inhibit biomineralization Mgp, Enpp1, Ank, and Spp1 were reduced in IVDs from ENT1(-/-) mice. To assess whether changes detected in ENT1(-/-) mice were cell autonomous, annulus fibrosus cell cultures were established. Compared to wild-type cells, cells isolated from ENT1(-/-) IVDs at 2 or 6months of age demonstrated greater activity of alkaline phosphatase, a promoter of biomineralization. Cells from 2-month-old ENT1(-/-) mice also showed greater mineralization than wild-type. Interestingly, altered localization of alkaline phosphatase activity was detected in the inner annulus fibrosus of ENT1(-/-) mice in vivo. Alkaline phosphatase activity, together with the marked reduction in mineralization inhibitors, is consistent with the mineralization of IVDs seen in ENT1(-/-) mice at older ages. These findings establish that both cell-autonomous and systemic mechanisms contribute to ectopic mineralization in ENT1(-/-) mice. Copyright © 2016 Elsevier Inc. All rights reserved.

Comparison of exogenous surfactant therapy, mechanical ventilation with high end-expiratory pressure and partial liquid ventilation in a model of acute lung injury.

PubMed

Hartog, A; Vazquez de Anda, G F; Gommers, D; Kaisers, U; Verbrugge, S J; Schnabel, R; Lachmann, B

1999-01-01

We have compared three treatment strategies, that aim to prevent repetitive alveolar collapse, for their effect on gas exchange, lung mechanics, lung injury, protein transfer into the alveoli and surfactant system, in a model of acute lung injury. In adult rats, the lungs were ventilated mechanically with 100% oxygen and a PEEP of 6 cm H2O, and acute lung injury was induced by repeated lung lavage to obtain a PaO2 value < 13 kPa. Animals were then allocated randomly (n = 12 in each group) to receive exogenous surfactant therapy, ventilation with high PEEP (18 cm H2O), partial liquid ventilation or ventilation with low PEEP (8 cm H2O) (ventilated controls). Blood-gas values were measured hourly. At the end of the 4-h study, in six animals per group, pressure-volume curves were constructed and bronchoalveolar lavage (BAL) was performed, whereas in the remaining animals lung injury was assessed. In the ventilated control group, arterial oxygenation did not improve and protein concentration of BAL and conversion of active to non-active surfactant components increased significantly. In the three treatment groups, PaO2 increased rapidly to > 50 kPa and remained stable over the next 4 h. The protein concentration of BAL fluid increased significantly only in the partial liquid ventilation group. Conversion of active to non-active surfactant components increased significantly in the partial liquid ventilation group and in the group ventilated with high PEEP. In the surfactant group and partial liquid ventilation groups, less lung injury was found compared with the ventilated control group and the group ventilated with high PEEP. We conclude that although all three strategies improved PaO2 to > 50 kPa, the impact on protein transfer into the alveoli, surfactant system and lung injury differed markedly.

Passive continuous positive airway pressure ventilation during cardiopulmonary resuscitation: a randomized cross-over manikin simulation study.

PubMed

Winkler, Bernd E; Muellenbach, Ralf M; Wurmb, Thomas; Struck, Manuel F; Roewer, Norbert; Kranke, Peter

2017-02-01

While controlled ventilation is most frequently used during cardiopulmonary resuscitation (CPR), the application of continuous positive airway pressure (CPAP) and passive ventilation of the lung synchronously with chest compressions and decompressions might represent a promising alternative approach. One benefit of CPAP during CPR is the reduction of peak airway pressures and therefore a potential enhancement in haemodynamics. We therefore evaluated the tidal volumes and airway pressures achieved during CPAP-CPR. During CPR with the LUCAS™ 2 compression device, a manikin model was passively ventilated at CPAP levels of 5, 10, 20 and 30 hPa with the Boussignac tracheal tube and the ventilators Evita ® V500, Medumat ® Transport, Oxylator ® EMX, Oxylog ® 2000, Oxylog ® 3000, Primus ® and Servo ® -i as well as the Wenoll ® diver rescue system. Tidal volumes and airway pressures during CPAP-CPR were recorded and analyzed. Tidal volumes during CPAP-CPR were higher than during compression-only CPR without positive airway pressure. The passively generated tidal volumes increased with increasing CPAP levels and were significantly influenced by the ventilators used. During ventilation at 20 hPa CPAP via a tracheal tube, the mean tidal volumes ranged from 125 ml (Medumat ® ) to 309 ml (Wenoll ® ) and the peak airway pressures from 23 hPa (Primus ® ) to 49 hPa (Oxylog ® 3000). Transport ventilators generated lower tidal volumes than intensive care ventilators or closed-circuit systems. Peak airway pressures during CPAP-CPR were lower than those during controlled ventilation CPR reported in literature. High peak airway pressures are known to limit the applicability of ventilation via facemask or via supraglottic airway devices and may adversely affect haemodynamics. Hence, the application of ventilators generating high tidal volumes with low peak airway pressures appears desirable during CPAP-CPR. The limited CPAP-CPR capabilities of transport ventilators in our study might be prerequisite for future developments of transport ventilators.

[Disinfectants and main sanitary and preventive measures for protection of ventilation and air-conditioning systems from Legionella contamination].

PubMed

Gerasimov, V N; Golov, E A; Khramov, M V; Diatlov, I A

2008-01-01

The study was devoted to selection and assessment of disinfecting preparations for prevention of contamination by Legionella. Using system of criteria for quality assessment of disinfectants, seven newdomestic ones belonging to quaternary ammonium compounds class or to oxygen-containing preparations and designed for disinfecting of air-conditioning and ventilation systems were selected. Antibacterial and disinfecting activities of working solutions of disinfectants were tested in laboratory on the test-surfaces and test-objects of premises' air-conditioning and ventilation systems contaminated with Legionella. High antimicrobial and disinfecting activity of new preparations "Dezactiv-M", "ExtraDez", "Emital-Garant", "Aquasept Plus", "Samarovka", "Freesept", and "Ecobreeze Oxy" during their exposure on objects and materials contaminated with Legionella was shown. Main sanitary and preventive measures for defending of air-conditioning and ventilation systems from contamination by Legionella species were presented.

Methane emissions and airflow patterns along longwall faces and through bleeder ventilation systems

PubMed Central

Schatzel, Steven J.; Dougherty, Heather N.

2015-01-01

The National Institute for Occupational Safety and Health (NIOSH) conducted an investigation of longwall face and bleeder ventilation systems using tracer gas experiments and computer network ventilation. The condition of gateroad entries, along with the caved material’s permeability and porosity changes as the longwall face advances, determine the resistance of the airflow pathways within the longwall’s worked-out area of the bleeder system. A series of field evaluations were conducted on a four-panel longwall district. Tracer gas was released at the mouth of the longwall section or on the longwall face and sampled at various locations in the gateroads inby the shield line. Measurements of arrival times and concentrations defined airflow/gas movements for the active/completed panels and the bleeder system, providing real field data to delineate these pathways. Results showed a sustained ability of the bleeder system to ventilate the longwall tailgate corner as the panels retreated. PMID:26925166

Utilizing a Suited Manikin Test Apparatus and Space Suit Ventilation Loop to Evaluate Carbon Dioxide Washout

NASA Technical Reports Server (NTRS)

Chullen, Cinda; Conger, Bruce; Korona, Adam; Kanne, Bryan; McMillin, Summer; Paul, Thomas; Norcross, Jason; Alonso, Jesus Delgado; Swickrath, Mike

2015-01-01

NASA is pursuing technology development of an Advanced Extravehicular Mobility Unit (AEMU) which is an integrated assembly made up of primarily a pressure garment system and a portable life support subsystem (PLSS). The PLSS is further composed of an oxygen subsystem, a ventilation subsystem, and a thermal subsystem. One of the key functions of the ventilation system is to remove and control the carbon dioxide (CO2) delivered to the crewmember. Carbon dioxide washout is the mechanism by which CO2 levels are controlled within the space suit helmet to limit the concentration of CO2 inhaled by the crew member. CO2 washout performance is a critical parameter needed to ensure proper and robust designs that are insensitive to human variabilities in a space suit. A suited manikin test apparatus (SMTA) was developed to augment testing of the PLSS ventilation loop in order to provide a lower cost and more controlled alternative to human testing. The CO2 removal function is performed by the regenerative Rapid Cycle Amine (RCA) within the PLSS ventilation loop and its performance is evaluated within the integrated SMTA and Ventilation Loop test system. This paper will provide a detailed description of the schematics, test configurations, and hardware components of this integrated system. Results and analysis of testing performed with this integrated system will be presented within this paper.

Test Protocol for Room-to-Room Distribution of Outside Air by Residential Ventilation Systems

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

Barley, C. D.; Anderson, R.; Hendron, B.

2007-12-01

This test and analysis protocol has been developed as a practical approach for measuring outside air distribution in homes. It has been used successfully in field tests and has led to significant insights on ventilation design issues. Performance advantages of more sophisticated ventilation systems over simpler, less-costly designs have been verified, and specific problems, such as airflow short-circuiting, have been identified.

Electrosurgical Smoke: Ultrafine Particle Measurements and Work Environment Quality in Different Operating Theatres

PubMed Central

Romano, Francesco; Gustén, Jan; De Antonellis, Stefano; Joppolo, Cesare M.

2017-01-01

Air cleanliness in operating theatres (OTs) is an important factor for preserving the health of both the patient and the medical staff. Particle contamination in OTs depends mainly on the surgery process, ventilation principle, personnel clothing systems and working routines. In many open surgical operations, electrosurgical tools (ESTs) are used for tissue cauterization. ESTs generate a significant airborne contamination, as surgical smoke. Surgical smoke is a work environment quality problem. Ordinary surgical masks and OT ventilation systems are inadequate to control this problem. This research work is based on numerous monitoring campaigns of ultrafine particle concentrations in OTs, equipped with upward displacement ventilation or with a downward unidirectional airflow system. Measurements performed during ten real surgeries highlight that the use of ESTs generates a quite sharp and relevant increase of particle concentration in the surgical area as well within the entire OT area. The measured contamination level in the OTs are linked to surgical operation, ventilation principle, and ESTs used. A better knowledge of airborne contamination is crucial for limiting the personnel’s exposure to surgical smoke. Research results highlight that downward unidirectional OTs can give better conditions for adequate ventilation and contaminant removal performances than OTs equipped with upward displacement ventilation systems. PMID:28146089

VWPS: A Ventilator Weaning Prediction System with Artificial Intelligence

NASA Astrophysics Data System (ADS)

Chen, Austin H.; Chen, Guan-Ting

How to wean patients efficiently off mechanical ventilation continues to be a challenge for medical professionals. In this paper we have described a novel approach to the study of a ventilator weaning prediction system (VWPS). Firstly, we have developed and written three Artificial Neural Network (ANN) algorithms to predict a weaning successful rate based on the clinical data. Secondly, we have implemented two user-friendly weaning success rate prediction systems; the VWPS system and the BWAP system. Both systems could be used to help doctors objectively and effectively predict whether weaning is appropriate for patients based on the patients' clinical data. Our system utilizes the powerful processing abilities of MatLab. Thirdly, we have calculated the performance through measures such as sensitivity and accuracy for these three algorithms. The results show a very high sensitivity (around 80%) and accuracy (around 70%). To our knowledge, this is the first design approach of its kind to be used in the study of ventilator weaning success rate prediction.

The necessity of HVAC system for the registered architectural cultural heritage building

NASA Astrophysics Data System (ADS)

Popovici, Cătălin George; Hudişteanu, Sebastian Valeriu; Cherecheş, Nelu-Cristian

2018-02-01

This study is intended to highlight the role of the ventilation and air conditioning system for a theatre. It was chosen as a case study the "Vasile Alecsandri" National Theatre of Jassy. The paper also sought to make a comparison in three distinct scenarios for HVAC Main Hall system - ventilation and air conditioning system of the Main Hall doesn't work; only the ventilation system of the Main Hall works and ventilation and air conditioning system of the Main Hall works. For analysing the comfort parameters, the ANSYS-Fluent software was used to build a 2D model of the building and simulation of HVAC system functionality during winter season, in all three scenarios. For the studied scenarios, the external conditions of Jassy and the indoor conditions of the theatre, when the entire spectacle hall is occupied were considered. The main aspects evaluated for each case were the air temperature, air velocity and relative humidity. The results are presented comparatively as plots and spectra of the interest parameters.

Burbank performs the scheduled extensive cleanup of ventilation systems

NASA Image and Video Library

2012-02-22

ISS030-E-093414 (22 Feb. 2012) --- NASA astronaut Dan Burbank, Expedition 30 commander, performs the scheduled extensive cleanup of ventilation systems in the Columbus laboratory of the International Space Station.

7. DETAIL, VENTILATION SYSTEM; EAST FRONT OF QUARANTINE GREENHOUSE #3 ...

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

7. DETAIL, VENTILATION SYSTEM; EAST FRONT OF QUARANTINE GREENHOUSE #3 (BUILDING 31) - U.S. Plant Introduction Station, Quarantine Headhouses & Greenhouses, 11601 Old Pond Road, Glenn Dale, Prince George's County, MD

Injuries to the Aorta, Aortic Annulus, and Left Ventricle During Transcatheter Aortic Valve Replacement: Management and Outcomes.

PubMed

Langer, Nathaniel B; Hamid, Nadira B; Nazif, Tamim M; Khalique, Omar K; Vahl, Torsten P; White, Jonathon; Terre, Juan; Hastings, Ramin; Leung, Diana; Hahn, Rebecca T; Leon, Martin; Kodali, Susheel; George, Isaac

2017-01-01

The experience with transcatheter aortic valve replacement is increasing worldwide; however, the incidence of potentially catastrophic cardiac or aortic complications has not decreased. In most cases, significant injuries to the aorta, aortic valve annulus, and left ventricle require open surgical repair. However, the transcatheter aortic valve replacement patient presents a unique challenge as many patients are at high or prohibitive surgical risk and, therefore, an open surgical procedure may not be feasible or appropriate. Consequently, prevention of these potentially catastrophic injuries is vital, and practitioners need to understand when open surgical repair is required and when alternative management strategies can be used. The goal of this article is to provide an overview of current management and prevention strategies for major complications involving the aorta, aortic valve annulus, and left ventricle. © 2016 American Heart Association, Inc.

Should the annular tendon of the eye be named 'annulus of Zinn' or 'of Valsalva'?

PubMed

Zampieri, Fabio; Marrone, Daniela; Zanatta, Alberto

2015-02-01

The annular tendon is commonly named 'annulus of Zinn', from the German anatomist and botanist Johann Gottfried Zinn (1727-1759) who described this structure in his Descriptio anatomica oculi humani (Anatomical Description of the Human Eye, 1755). This structure, however, had been previously discovered not by Zinn, but by Antonio Maria Valsalva (1666-1723) some decades before the publication of Zinn, in his Dissertatio anatomica prima and Dissertatio anatomica altera (First and Second Anatomical Dissertations), inside Valsalva's Opera omnia published in 1740. We advance that this structure could be re-named such as 'annulus of Valsalva-Zinn' because Valsalva, even making a mistake in its functional interpretation, first described this anatomical structure. Likewise, Valsalva, with his discovery, advanced a revolutionary idea for that time on the usefulness of anatomy for clinic and pathology. © 2014 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Cues used by the black fly, Simulium annulus, for attraction to the common loon (Gavia immer).

PubMed

Weinandt, Meggin L; Meyer, Michael; Strand, Mac; Lindsay, Alec R

2012-12-01

The parasitic relationship between a black fly, Simulium annulus, and the common loon (Gavia immer) has been considered one of the most exclusive relationships between any host species and a black fly species. To test the host specificity of this blood-feeding insect, we made a series of bird decoy presentations to black flies on loon-inhabited lakes in northern Wisconsin, U.S.A. To examine the importance of chemical and visual cues for black fly detection of and attraction to hosts, we made decoy presentations with and without chemical cues. Flies attracted to the decoys were collected, identified to species, and quantified. Results showed that S. annulus had a strong preference for common loon visual and chemical cues, although visual cues from Canada geese (Branta canadensis) and mallards (Anas platyrynchos) did attract some flies in significantly smaller numbers. © 2012 The Society for Vector Ecology.

The effect of closed system suction on airway pressures when using the Servo 300 ventilator.

PubMed

Frengley, R W; Closey, D N; Sleigh, J W; Torrance, J M

2001-12-01

To measure airway pressures during closed system suctioning with the ventilator set to three differing modes of ventilation. Closed system suctioning was conducted in 16 patients following cardiac surgery. Suctioning was performed using a 14 French catheter with a vacuum level of -500 cmH2O through an 8.0 mm internal diameter endotracheal tube. The lungs were mechanically ventilated with a Servo 300 ventilator set to one of three ventilation modes: volume-control, pressure-control or CPAP/pressure support. Airway pressures were measured via a 4 French electronic pressure transducer in both proximal and distal airways. Following insertion of the suction catheter, end-expiratory pressure increased significantly (p < 0.001) in both pressure-control and volume-control ventilation. This increase was greatest (p = 0.018) in volume-control mode (2.7 +/- 1.7 cmH2O). On performing a five second suction, airway pressure decreased in all modes, however the lowest airway pressure in volume-control mode (-4.9 +/- 4.0 cmH2O) was significantly (p = 0.001) less than the lowest airway pressure recorded in either pressure-control (0.8 +/- 1.9 cmH2O) or CPAP/pressure support (0.4 +/- 2.8 cmH2O) modes. In CPAP/pressure support mode, 13 of the 16 patients experienced a positive pressure 'breath' at the end of suctioning with airway pressures rising to 21 +/- 1.6 cmH2O. Closed system suctioning in volume control ventilation may result in elevations of end-expiratory pressure following catheter insertion and subatmospheric airway pressures during suctioning. Pressure control ventilation produces less elevation of end-expiratory pressure following catheter insertion and is less likely to be associated with subatmospheric airway pressures during suctioning. CPAP/pressure support has no effect on end-expiratory pressure following catheter insertion and subatmospheric airway pressures are largely avoided during suctioning.

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

Poppiti, James; Nelson, Roger; MacMillan, Walter J.

The Waste Isolation Pilot Plant (WIPP) is a 655-meter deep mine near Carlsbad, New Mexico, used to dispose the nation’s defense transuranic waste. Limited airborne radioactivity was released from a container of radioactive waste in WIPP on 14 February, 2014. As designed, a mine ventilation filtration system prevented the large scale release of contamination from the underground. However, isolation dampers leaked, which allowed the release of low levels of contaminants after the event until they were sealed. None of the exposed individuals received any recordable dose. While surface contamination was limited, contamination in the ventilation system and portions of themore » underground was substantial. High efficiency particulate air (HEPA) filters in the operating ventilation system ensure continued containment during recovery and resumption of disposal operations. However, ventilation flow is restricted since the incident, with all exhaust air directed through the filters. Decontamination and natural fixation by the hygroscopic nature of the salt host rock has reduced the likelihood of further contamination spread. Contamination control and ventilation system operability are crucial for resumption of operations. This article provides an operational assessment and evaluation of these two key areas.« less

Short-term airing by natural ventilation - implication on IAQ and thermal comfort.

PubMed

Heiselberg, P; Perino, M

2010-04-01

The need to improve the energy efficiency of buildings requires new and more efficient ventilation systems. It has been demonstrated that innovative operating concepts that make use of natural ventilation seem to be more appreciated by occupants. Among the available ventilation strategies that are currently available, buoyancy driven, single-sided natural ventilation has proved to be very effective and can provide high air change rates for temperature and Indoor Air Quality (IAQ) control. However, to promote a wider distribution of these systems an improvement in the knowledge of their working principles is necessary. The present study analyses and presents the results of an experimental evaluation of airing performance in terms of ventilation characteristics, IAQ and thermal comfort. It includes investigations of the consequences of opening time, opening frequency, opening area and expected airflow rate, ventilation efficiency, thermal comfort and dynamic temperature conditions. A suitable laboratory test rig was developed to perform extensive experimental analyses of the phenomenon under controlled and repeatable conditions. The results showed that short-term window airing is very effective and can provide both acceptable IAQ and thermal comfort conditions in buildings. Practical Implications This study gives the necessary background and in-depth knowledge of the performance of window airing by single-sided natural ventilation necessary for the development of control strategies for window airing (length of opening period and opening frequency) for optimum IAQ and thermal comfort in naturally ventilated buildings.

Multifamily Individual Heating and Ventilation Systems, Lawrence, Massachusetts (Fact Sheet)

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

Not Available

The conversion of an older Massachusetts building into condominiums illustrates a safe, durable, and cost-effective solution for heating and ventilation systems that can potentially benefit millions of multifamily buildings. Merrimack Valley Habitat for Humanity (MVHfH) partnered with U.S. Department of Energy Building America team Building Science Corporation (BSC) to provide high performance affordable housing for 10 families in the retrofit of an existing mass masonry building (a former convent). The original ventilation design for the project was provided by a local engineer and consisted of a single large heat recovery ventilator (HRV) located in a mechanical room in the basementmore » with a centralized duct system providing supply air to the main living space and exhausting stale air from the single bathroom in each apartment. This design was deemed to be far too costly to install and operate for several reasons: the large central HRV was oversized and the specified flows to each apartment were much higher than the ASHRAE 62.2 rate; an extensive system of ductwork, smoke and fire dampers, and duct chases were specified; ductwork required a significant area of dropped ceilings; and the system lacked individual ventilation control in the apartments« less

Effect of scanline orientation on ventricular flow propagation: assessment using high frame-rate color Doppler echocardiography

NASA Technical Reports Server (NTRS)

Greenberg, N. L.; Castro, P. L.; Drinko, J.; Garcia, M. J.; Thomas, J. D.

2000-01-01

Color M-mode echocardiography has recently been utilized to describe diastolic flow propagation velocity (Vp) in the left ventricle. While increasing temporal resolution from 15 to 200 Hz, this M-mode technique requires the user to select a single scanline, potentially limiting quantification of Vp due to the complex three-dimensional inflow pattern. We previously performed computational fluid dynamics simulations to demonstrate the insignificance of the scanline orientation, however geometric complexity was limited. The purpose of this study was to utilize high frame-rate 2D color Doppler images to investigate the importance of scanline selection in patients for the quantification of Vp. 2D color Doppler images were digitally acquired at 50 frames/s in 6 subjects from the apical 4-chamber window (System 5, GE/Vingmed, Milwaukee, WI). Vp was determined for a set of scanlines positioned through 5 locations across the mitral annulus (from the anterior to posterior mitral annulus). An analysis of variance was performed to examine the differences in Vp as a function of scanline position. Vp was not effected by scanline position in sampled locations from the center of the mitral valve towards the posterior annulus. Although not statistically significant, there was a trend to slower propagation velocities on the anterior side of the valve (60.8 +/- 16.7 vs. 54.4 +/- 13.6 cm/s). This study clinically validates our previous numerical experiment showing that Vp is insensitive to small perturbations of the scanline through the mitral valve. However, further investigation is necessary to examine the impact of ventricular geometry in pathologies including dilated cardiomyopathy.

Innovative ventilation system for animal anatomy laboratory

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

Lacey, D.R.; Smith, D.C.

1997-04-01

A unique ventilation system was designed and built to reduce formaldehyde fumes in the large animal anatomy lab at the Vet Medical Center at Cornell University. The laboratory includes four rooms totaling 5,500 ft{sup 2}. The main room has 2,300 ft{sup 2} and houses the laboratory where up to 60 students dissect as many as 12 horses at a time. Other rooms are a cold storage locker, an animal preparation room and a smaller lab for specialized instruction. The large animal anatomy laboratory has a history of air quality complaints despite a fairly high ventilation rate of over 10 airmore » changes/hour. The horses are embalmed, creating a voluminous source of formaldehyde and phenol vapors. Budget constraints and increasingly stringent exposure limits for formaldehyde presented a great challenge to design a ventilation system that yields acceptable air quality. The design solution included two innovative elements: air-to-air heat recovery, and focused ventilation.« less

Change-over natural and mechanical ventilation system energy consumption in single-family buildings

NASA Astrophysics Data System (ADS)

Kostka, Maria; Szulgowska-Zgrzywa, Małgorzata

2017-11-01

The parameters of the outside air in Poland cause that in winter it is reasonable to use a mechanical ventilation equipped with a heat recovery exchanger. The time of spring, autumn, summer evenings and nights are often characterized by the parameters of the air, which allow for a natural ventilation and reduce the electricity consumption. The article presents the possibilities of energy consumption reduction for three energy standards of buildings located in Poland, ventilated by a change-over hybrid system. The analysis was prepared on the assumption that the air-to-water heat pump is the heat source for the buildings.

Building Assessment Survey and Evaluation (BASE) Study: Summarized Data - Test Space HVAC Characteristics

EPA Pesticide Factsheets

Information on the characteristics of the heating, ventilation, and air conditioning (HVAC) system(s) in the entire BASE building including types of ventilation, equipment configurations, and operation and maintenance issues

ACHP | News | ACHP Issues Program Comment for GSA on Select Repairs and

Science.gov Websites

to windows, lighting, roofing, and heating, ventilating, and air-conditioning (HVAC) systems within Upgrades Windows Lighting Roofing Heating, Ventilation, and Air Conditioning (HVAC) Systems Updated March

SUBSURFACE VOLATIZATION AND VENTILATION SYSTEM (SVVS) - INNOVATIVE TECHNOLOGY REPORT

EPA Science Inventory

This report summarizes the findings associated with a Demonstration Test of Environmental Improvement Technologies’ (EIT) Subsurface Volatilization and Ventilation System (SVVS) process. The technology was evaluated under the EPA Superfund Innovative Technology Evaluation (SITE) ...

Ventilation.

PubMed

Turner, W A; Bearg, D W; Brennan, T

1995-01-01

This chapter begins with an overview of the history of ventilation guidelines, which has led to the guidelines that are in effect today. Of particular interest is the most recent return in the past 5 years to ventilation rates that more closely reflect a mean or average of the range of guidelines that have existed over the past century. OSHA's and the EPA's recognition of the need to operate ventilation systems in buildings in an accountable manner is also of note. Of even more interest is the resurgence of the concept of minimum mixing and once-through ventilation air that has been pursued in parts of Northern Europe for the past 10 years, and in a school that is being designed with this concept in New Hampshire. In addition, the design concept of equipping office buildings with low pressure drop high efficiency particle filtration to remove fine particles from all of the air that is supplied to the occupants is being used increasingly in the U.S. This chapter also presents an overview of the various types of ventilation systems found in homes and commercial office buildings and the common indoor air quality problems that may be associated with them. It also offers an overview of common HVAC evaluation techniques that can be used to determine if a ventilation system is performing in a manner that makes sense for the use of the space and the needs of the occupants. Are the occupants receiving a reasonable supply of outdoor air? Is the air that they receive of reasonable quality? Are obvious pollutants being exhausted? Ventilation systems have become extremely complex and more difficult to run and maintain over the past 40 years. This trend will continue to drive the need for professionally maintained HVAC equipment that is serviced and run by individuals who are accountable for the quality of the air that the system delivers.

46 CFR 154.1205 - Mechanical ventilation system: Standards.

Code of Federal Regulations, 2013 CFR

2013-10-01

... operational controls outside the ventilated space. (g) No ventilation duct for a gas-dangerous space may pass... Section 154.1205 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and...

46 CFR 154.1205 - Mechanical ventilation system: Standards.

Code of Federal Regulations, 2014 CFR

2014-10-01

... operational controls outside the ventilated space. (g) No ventilation duct for a gas-dangerous space may pass... Section 154.1205 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and...

46 CFR 154.1205 - Mechanical ventilation system: Standards.

Code of Federal Regulations, 2012 CFR

2012-10-01

... operational controls outside the ventilated space. (g) No ventilation duct for a gas-dangerous space may pass... Section 154.1205 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and...

Respiratory mechanics in brain injury: A review.

PubMed

Koutsoukou, Antonia; Katsiari, Maria; Orfanos, Stylianos E; Kotanidou, Anastasia; Daganou, Maria; Kyriakopoulou, Magdalini; Koulouris, Nikolaos G; Rovina, Nikoletta

2016-02-04

Several clinical and experimental studies have shown that lung injury occurs shortly after brain damage. The responsible mechanisms involve neurogenic pulmonary edema, inflammation, the harmful action of neurotransmitters, or autonomic system dysfunction. Mechanical ventilation, an essential component of life support in brain-damaged patients (BD), may be an additional traumatic factor to the already injured or susceptible to injury lungs of these patients thus worsening lung injury, in case that non lung protective ventilator settings are applied. Measurement of respiratory mechanics in BD patients, as well as assessment of their evolution during mechanical ventilation, may lead to preclinical lung injury detection early enough, allowing thus the selection of the appropriate ventilator settings to avoid ventilator-induced lung injury. The aim of this review is to explore the mechanical properties of the respiratory system in BD patients along with the underlying mechanisms, and to translate the evidence of animal and clinical studies into therapeutic implications regarding the mechanical ventilation of these critically ill patients.

Effect of flashlight guidance on manual ventilation performance in cardiopulmonary resuscitation: A randomized controlled simulation study.

PubMed

Kim, Ji Hoon; Beom, Jin Ho; You, Je Sung; Cho, Junho; Min, In Kyung; Chung, Hyun Soo

2018-01-01

Several auditory-based feedback devices have been developed to improve the quality of ventilation performance during cardiopulmonary resuscitation (CPR), but their effectiveness has not been proven in actual CPR situations. In the present study, we investigated the effectiveness of visual flashlight guidance in maintaining high-quality ventilation performance. We conducted a simulation-based, randomized, parallel trial including 121 senior medical students. All participants were randomized to perform ventilation during 2 minutes of CPR with or without flashlight guidance. For each participant, we measured mean ventilation rate as a primary outcome and ventilation volume, inspiration velocity, and ventilation interval as secondary outcomes using a computerized device system. Mean ventilation rate did not significantly differ between flashlight guidance and control groups (P = 0.159), but participants in the flashlight guidance group exhibited significantly less variation in ventilation rate than participants in the control group (P<0.001). Ventilation interval was also more regular among participants in the flashlight guidance group. Our results demonstrate that flashlight guidance is effective in maintaining a constant ventilation rate and interval. If confirmed by further studies in clinical practice, flashlight guidance could be expected to improve the quality of ventilation performed during CPR.

Experimental research on the indoor temperature and humidity fields in radiant ceiling air-conditioning system under natural ventilation

NASA Astrophysics Data System (ADS)

Huang, Tao; Xiang, Yutong; Wang, Yonghong

2017-05-01

In this paper, the indoor temperature and humidity fields of the air in a metal ceiling radiant panel air conditioning system with fresh air under natural ventilation were researched. The temperature and humidity distributions at different height and different position were compared. Through the computation analysis of partial pressure of water vapor, the self-recovery characteristics of humidity after the natural ventilation was discussed.

Alternatives generation and analysis for double-shell tank primary ventilation systems emissions control and monitoring

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

SEDERBURG, J.P.

1999-09-30

This AGA addresses the question: ''What equipment upgrades, operational changes, and/or other actions are required relative to the DST tanks farms' ventilation systems to support retrieval, staging (including feed sampling), and delivery of tank waste to the Phase I private contractor?'' Issues and options for the various components within the ventilation subsystem affect each other. Recommended design requirements are presented and the preferred alternatives are detailed.

Study of Alternate Material for Pedal Ventilator Kits.

DTIC Science & Technology

1980-04-01

to fans with diameters of 36 inches or less, revealed that a shelter ventilation system of minimum cost would require three units with 36-inch...doorways, it was decided, with OCD approval, to develop pre-assembled one and two-operator bicycle ventilator kits utilizing a fan and ducting system of...polypropylene matrix. According to Ford Motor Company, an enthusiastic user, this material hybrid offers large potential savings in direct substitution for glass

Water spray ventilator system for continuous mining machines

DOEpatents

Page, Steven J.; Mal, Thomas

1995-01-01

The invention relates to a water spray ventilator system mounted on a continuous mining machine to streamline airflow and provide effective face ventilation of both respirable dust and methane in underground coal mines. This system has two side spray nozzles mounted one on each side of the mining machine and six spray nozzles disposed on a manifold mounted to the underside of the machine boom. The six spray nozzles are angularly and laterally oriented on the manifold so as to provide non-overlapping spray patterns along the length of the cutter drum.

International Space Station USOS Crew Quarters Ventilation and Acoustic Design Implementation

NASA Technical Reports Server (NTRS)

Broyan, James Lee, Jr.

2009-01-01

The International Space Station (ISS) United States Operational Segment (USOS) has four permanent rack sized ISS Crew Quarters (CQ) providing a private crewmember space. The CQ uses Node 2 cabin air for ventilation/thermal cooling, as opposed to conditioned ducted air from the ISS Temperature Humidity Control System or the ISS fluid cooling loop connections. Consequently, CQ can only increase the air flow rate to reduce the temperature delta between the cabin and the CQ interior. However, increasing airflow causes increased acoustic noise so efficient airflow distribution is an important design parameter. The CQ utilized a two fan push-pull configuration to ensure fresh air at the crewmember s head position and reduce acoustic exposure. The CQ interior needs to be below Noise Curve 40 (NC-40). The CQ ventilation ducts are open to the significantly louder Node 2 cabin aisle way which required significantly acoustic mitigation controls. The design implementation of the CQ ventilation system and acoustic mitigation are very inter-related and require consideration of crew comfort balanced with use of interior habitable volume, accommodation of fan failures, and possible crew uses that impact ventilation and acoustic performance. This paper illustrates the types of model analysis, assumptions, vehicle interactions, and trade-offs required for CQ ventilation and acoustics. Additionally, on-orbit ventilation system performance and initial crew feedback is presented. This approach is applicable to any private enclosed space that the crew will occupy.

Biomechanical Characterization of an Annulus Sparing Spinal Disc Prosthesis

PubMed Central

Buttermann, Glenn R.; Beaubien, Brian P.

2009-01-01

Background Context Current spine arthroplasty devices, require disruption of the annulus fibrosus for implantation. Preliminary studies of a unique annulus sparing intervertebral prosthetic disc (IPD), found that preservation of the annulus resulted in load sharing of the annulus with the prosthesis. Purpose Determine flexibility of the IPD versus fusion constructs in normal and degenerated human spines. Study design/Setting Biomechanical comparison of motion segments in the intact, fusion and mechanical nucleus replacement states for normal and degenerated states. Patient setting Thirty lumbar motion segments. Outcomes Measures Intervertebral height; motion segment range-of-motion (ROM), neutral zone (NZ), stiffness. Methods Motion segments had multi-directional flexibility testing to 7.5 Nm for intact discs, discs reconstructed using the IPD (n=12), or after anterior/posterior fusions (n=18). Interbody height and axial compression stiffness changes were determined for the reconstructed discs by applying axial compression to 1500 N. Analysis included stratifying results to normal mobile vs. rigid degenerated intact motion segments. Results The mean interbody height increase was 1.5 mm for IPD reconstructed discs. vs 3.0 mm for fused segments. Axial compression stiffness was 3.0 ± 0.9 kN/mm for intact compared to 1.2 ± 0.4 kN/mm for IPD reconstructed segments. Reconstructed disc ROM was 9.0° ± 3.7° in flexion-extension, 10.6° ± 3.4° in lateral bending and 2.8° ± 1.4° in axial torsion which was similar to intact values and significantly greater than respective fusion values (p<0.001). Mobile intact segments exhibited significantly greater rotation after fusion vs. their more rigid counterparts (p<0.05), however, intact motion was not related to motion after IPD reconstruction. The NZ and rotational stiffness followed similar trends. Differences in NZ between mobile and rigid intact specimens tended to decrease in the IPD reconstructed state. Conclusion The annulus sparing IPD generally reproduced the intact segment biomechanics in terms of ROM, NZ, and stiffness. Furthermore, the IPD reconstructed discs imparted stability by maintaining a small neutral zone. The IPD reconstructed discs were significantly less rigid than the fusion constructs and may be an attractive alternative for the treatment of DDD. PMID:19540816

Antibiotic therapy in ventilator-associated tracheobronchitis: a literature review.

PubMed

Alves, Abel Eduardo; Pereira, José Manuel

2018-03-01

The concept of ventilator-associated tracheobronchitis is controversial; its definition is not unanimously accepted and often overlaps with ventilator-associated pneumonia. Ventilator-associated tracheobronchitis has an incidence similar to that of ventilator-associated pneumonia, with a high prevalence of isolated multiresistant agents, resulting in an increase in the time of mechanical ventilation and hospitalization but without an impact on mortality. The performance of quantitative cultures may allow better diagnostic definition of tracheobronchitis associated with mechanical ventilation, possibly avoiding the overdiagnosis of this condition. One of the major difficulties in differentiating between ventilator-associated tracheobronchitis and ventilator-associated pneumonia is the exclusion of a pulmonary infiltrate by chest radiography; thoracic computed tomography, thoracic ultrasonography, or invasive specimen collection may also be required. The institution of systemic antibiotic therapy does not improve the clinical impact of ventilator-associated tracheobronchitis, particularly in reducing time of mechanical ventilation, hospitalization or mortality, despite the possible reduced progression to ventilator-associated pneumonia. However, there are doubts regarding the methodology used. Thus, considering the high prevalence of tracheobronchitis associated with mechanical ventilation, routine treatment of this condition would result in high antibiotic usage without clear benefits. However, we suggest the institution of antibiotic therapy in patients with tracheobronchitis associated with mechanical ventilation and septic shock and/or worsening of oxygenation, and other auxiliary diagnostic tests should be simultaneously performed to exclude ventilator-associated pneumonia. This review provides a better understanding of the differentiation between tracheobronchitis associated with mechanical ventilation and pneumonia associated with mechanical ventilation, which can significantly decrease the use of antibiotics in critically ventilated patients.

Surgical clothing systems in laminar airflow operating room: a numerical assessment.

PubMed

Sadrizadeh, Sasan; Holmberg, Sture

2014-01-01

This study compared two different laminar airflow distribution strategies - horizontal and vertical - and investigated the effectiveness of both ventilation systems in terms of reducing the sedimentation and distribution of bacteria-carrying particles. Three different staff clothing systems, which resulted in source strengths of 1.5, 4 and 5 CFU/s per person, were considered. The exploration was conducted numerically using a computational fluid dynamics technique. Active and passive air sampling methods were simulated in addition to recovery tests, and the results were compared. Model validation was performed through comparisons with measurement data from the published literature. The recovery test yielded a value of 8.1 min for the horizontal ventilation scenario and 11.9 min for the vertical ventilation system. Fewer particles were captured by the slit sampler and in sedimentation areas with the horizontal ventilation system. The simulated results revealed that under identical conditions in the examined operating room, the horizontal laminar ventilation system performed better than the vertical option. The internal constellation of lamps, the surgical team and objects could have a serious effect on the movement of infectious particles and therefore on postoperative surgical site infections. Copyright © 2014 King Saud Bin Abdulaziz University for Health Sciences. Published by Elsevier Ltd. All rights reserved.

Microclimate measuring and fluid‑dynamic simulation in an industrial broiler house: testing of an experimental ventilation system.

PubMed

Bianchi, Biagio; Giametta, Ferruccio; La Fianza, Giovanna; Gentile, Andrea; Catalano, Pasquale

2015-01-01

The environment in the broiler house is a combination of physical and biological factors generating a complex dynamic system of interactions between birds, husbandry system, light, temperature, and the aerial environment. Ventilation plays a key role in this scenario. It is pivotal to remove carbon dioxide and water vapor from the air of the hen house. Adequate ventilation rates provide the most effective method of controlling temperature within the hen house. They allow for controlling the relative humidity and can play a key role in alleviating the negative effects of high stocking density and of wet litter. In the present study the results of experimental tests performed in a breeding broiler farm are shown. In particular the efficiency of a semi transversal ventilation system was studied against the use of a pure transversal one. In order to verify the efficiency of the systems, fluid dynamic simulations were carried out using the software Comsol multiphysics. The results of this study show that a correct architectural and structural design of the building must be supported by a design of the ventilation system able to maintain the environmental parameters within the limits of the thermo‑neutral and welfare conditions and to achieve the highest levels of productivity.

29 CFR 1926.62 - Lead.

Code of Federal Regulations, 2013 CFR

2013-07-01

... annually to reflect the current status of the program. (3) Mechanical ventilation. When ventilation is used... potentially harmful effects of exposure to lead. (vii)(A) The employer shall ensure that the containers of... remove lead from any surface unless the compressed air is used in conjunction with a ventilation system...

29 CFR 1926.62 - Lead.

Code of Federal Regulations, 2012 CFR

2012-07-01

... annually to reflect the current status of the program. (3) Mechanical ventilation. When ventilation is used... potentially harmful effects of exposure to lead. (vii)(A) The employer shall ensure that the containers of... remove lead from any surface unless the compressed air is used in conjunction with a ventilation system...

29 CFR 1926.62 - Lead.

Code of Federal Regulations, 2010 CFR

2010-07-01

... annually to reflect the current status of the program. (3) Mechanical ventilation. When ventilation is used... potentially harmful effects of exposure to lead. (vii) The employer shall assure that the containers of... remove lead from any surface unless the compressed air is used in conjunction with a ventilation system...

29 CFR 1926.62 - Lead.

Code of Federal Regulations, 2014 CFR

2014-07-01

... annually to reflect the current status of the program. (3) Mechanical ventilation. When ventilation is used... potentially harmful effects of exposure to lead. (vii)(A) The employer shall ensure that the containers of... remove lead from any surface unless the compressed air is used in conjunction with a ventilation system...

29 CFR 1926.62 - Lead.

Code of Federal Regulations, 2011 CFR

2011-07-01

... annually to reflect the current status of the program. (3) Mechanical ventilation. When ventilation is used... potentially harmful effects of exposure to lead. (vii) The employer shall assure that the containers of... remove lead from any surface unless the compressed air is used in conjunction with a ventilation system...

Tricuspid regurgitation due to chest trauma: an unusual laceration around the annulus of the anterior leaflet.

PubMed

Ishii, K; Koga, Y; Maeda, M; Nakamura, K; Sekiya, R; Yonezawa, T; Onitsuka, T; Shibata, K

1988-01-01

A 70-year-old male with tricuspid regurgitation due to a blunt chest trauma inflicted 16 years previously underwent prosthetic valve replacement. At surgery, a tear, which produced tricuspid regurgitation, was found around the annulus of the anterior leaflet of the tricuspid valve. Since this area has not been reported as a location for heart trauma-producing tricuspid regurgitation, a possible mechanism of tricuspid regurgitation is discussed in this patient.

Assessment of Natural Ventilation System for a Typical Residential House in Poland

NASA Astrophysics Data System (ADS)

Antczak-Jarząbska, Romana; Krzaczek, Marek

2016-09-01

The paper presents the research results of field measurements campaign of natural ventilation performance and effectiveness in a residential building. The building is located in the microclimate whose parameters differ significantly in relation to a representative weather station. The measurement system recorded climate parameters and the physical variables characterizing the air flow in the rooms within 14 days of the winter season. The measurement results showed that in spite of proper design and construction of the ventilation system, unfavorable microclimatic conditions that differed from the predicted ones caused significant reduction in the efficiency of the ventilation system. Also, during some time periods, external climate conditions caused an opposite air flow direction in the vent inlets and outlets, leading to a significant deterioration of air quality and thermal comfort measured by CO2 concentration and PMV index in a residential area.

Annular dynamics of memo3D annuloplasty ring evaluated by 3D transesophageal echocardiography.

PubMed

Nishi, Hiroyuki; Toda, Koichi; Miyagawa, Shigeru; Yoshikawa, Yasushi; Fukushima, Satsuki; Yoshioka, Daisuke; Sawa, Yoshiki

2018-04-01

We assessed the mitral annular motion after mitral valve repair with the Sorin Memo 3D® (Sorin Group Italia S.r.L., Saluggia, Italy), which is a unique complete semirigid annuloplasty ring intended to restore the systolic profile of the mitral annulus while adapting to the physiologic dynamism of the annulus, using transesophageal real-time three-dimensional echocardiography. 17 patients (12 male; mean age 60.4 ± 14.9 years) who underwent mitral annuloplasty using the Memo 3D ring were investigated. Mitral annular motion was assessed using QLAB®version8 allowing for a full evaluation of the mitral annulus dynamics. The mitral annular dimensions were measured throughout the cardiac cycle using 4D MV assessment2® while saddle shape was assessed through sequential measurements by RealView®. Saddle shape configuration of the mitral annulus and posterior and anterior leaflet motion could be observed during systole and diastole. The mitral annular area changed during the cardiac cycle by 5.7 ± 1.8%.The circumference length and diameter also changed throughout the cardiac cycle. The annular height was significantly higher in mid-systole than in mid-diastole (p < 0.05). The Memo 3D ring maintained a physiological saddle-shape configuration throughout the cardiac cycle. Real-time three-dimensional echocardiography analysis confirmed the motion and flexibility of the Memo 3D ring upon implantation.

Inclusion of Regional Poroelastic Material Properties Better Predicts Biomechanical Behavior of Lumbar Discs Subjected to Dynamic Loading

PubMed Central

Williams, Jamie R.; Natarajan, Raghu N.; Andersson, Gunnar B.J.

2009-01-01

Understanding the relationship between repetitive lifting and the breakdown of disc tissue over several years of exposure is difficult to study in vivo and in vitro. The aim of this investigation was to develop a three-dimensional poroelastic finite element model of a lumbar motion segment that reflects the biological properties and behaviors of in vivo disc tissues including swelling pressure due to the proteoglycans and strain dependent permeability and porosity. It was hypothesized that when modeling the annulus, prescribing tissue specific material properties will not be adequate for studying the in vivo loading and unloading behavior of the disc. Rather, regional variations of these properties, which are known to exist within the annulus, must also be included. Finite element predictions were compared to in vivo measurements published by Tyrrell et al., (Tyrrell et al., 1985) of percent change in total stature for two loading protocols, short-term creep loading and standing recovery and short-term cyclic loading with standing recovery. The model in which the regional variations of material properties in the annulus had been included provided an overall better prediction of the in vivo behavior as compared to the model in which the annulus properties were assumed to be homogenous. This model will now be used to study the relationship between repetitive lifting and disc degeneration. PMID:17156786

Body surface area as a key determinant of aortic root and arch dimensions in a population-based study.

PubMed

Wang, Yan-Li; Wang, Qing-Ling; Wang, Liang; Wu, Ying-Biao; Wang, Zhi-Bin; Cameron, James; Liang, Yu-Lu

2013-02-01

The associations between the aortic dimensions (of the aortic sinus, aortic annulus and aortic arch) and physiological variables have not been established in the Chinese population. The present study examined the associations among physiological variables to determine the aortic root and arch dimensions echocardiographically. The diameters of the aortic sinus, annulus and arch were measured in 1,010 subjects via 2-D echocardiography with a 3.5-MHz transducer in a trans-thoracic position. The images of the aortic sinus and aortic annulus were obtained from a standard parasternal long-axis view. The maximum diameter of the valve orifice was measured at the end of systole. The aortic arch dimension was visualized in the long-axis using a suprasternal notch window and the maximum transverse diameter was measured. Epidata 3.0, Excel 2007 and SPSS version 17.0 were used to collect and analyze the data. A total of 1,010 subjects were enrolled. The mean age was 55.0±17.0 years (range of 18 to 90 years). The body surface area (BSA) was the best predictor of all the studied physiological variables and may be used to predict aortic sinus, annulus and arch dimensions independently (r=0.54, 0.37 and 0.39, respectively). Gender, blood pressure, age and BSA are significant predictors of the aortic dimensions. Of these, BSA was the best predictor.

High Resolution N-Body Simulations of Terrestrial Planet Growth

NASA Astrophysics Data System (ADS)

Clark Wallace, Spencer; Quinn, Thomas R.

2018-04-01

We investigate planetesimal accretion with a direct N-body simulation of an annulus at 1 AU around a 1 M_sun star. The planetesimal ring, which initially contains N = 106 bodies is evolved through the runaway growth stage into the phase of oligarchic growth. We find that the mass distribution of planetesimals develops a bump around 1022 g shortly after the oligarchs form. This feature is absent in previous lower resolution studies. We find that this bump marks a boundary between growth modes. Below the bump mass, planetesimals are packed tightly enough together to populate first order mean motion resonances with the oligarchs. These resonances act to heat the tightly packed, low mass planetesimals, inhibiting their growth. We examine the eccentricity evolution of a dynamically hot planetary embryo embedded in an annulus of planetesimals and find that dynamical friction acts more strongly on the embryo when the planetesimals are finely resolved. This effect disappears when the annulus is made narrow enough to exclude most of the mean motion resonances. Additionally, we find that the 1022 g bump is significantly less prominent when we follow planetesimal growth with a skinny annulus.This feature, which is reminiscent of the power law break seen in the size distribution of asteroid belt objects may be an important clue for constraining the initial size of planetesimals in planet formation models.

Aortic annulus eccentricity before and after transcatheter aortic valve implantation: Comparison of balloon-expandable and self-expanding prostheses.

PubMed

Schuhbaeck, Annika; Weingartner, Christina; Arnold, Martin; Schmid, Jasmin; Pflederer, Tobias; Marwan, Mohamed; Rixe, Johannes; Nef, Holger; Schneider, Christian; Lell, Michael; Uder, Michael; Ensminger, Stephan; Feyrer, Richard; Weyand, Michael; Achenbach, Stephan

2015-07-01

The geometry of the aortic annulus and implanted transcatheter aortic valve prosthesis might influence valve function. We investigated the influence of valve type and aortic valve calcification on post-implant geometry of catheter-based aortic valve prostheses. Eighty consecutive patients with severe aortic valve stenosis (mean age 82 ± 6 years) underwent computed tomography before and after TAVI. Aortic annulus diameters were determined. Influence of prosthesis type and degree of aortic valve calcification on post-implant eccentricity were analysed. Aortic annulus eccentricity was reduced in patients after TAVI (0.21 ± 0.06 vs. 0.08 ± 0.06, p<0.0001). Post-TAVI eccentricity was significantly lower in 65 patients following implantation of a balloon-expandable prosthesis as compared to 15 patients who received a self-expanding prosthesis (0.06 ± 0.05 vs. 0.15 ± 0.07, p<0.0001), even though the extent of aortic valve calcification was not different. After TAVI, patients with a higher calcium amount retained a significantly higher eccentricity compared to patients with lower amounts of calcium. Patients undergoing TAVI with a balloon-expandable prosthesis show a more circular shape of the implanted prosthesis as compared to patients with a self-expanding prosthesis. Eccentricity of the deployed prosthesis is affected by the extent of aortic valve calcification. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Characterization of interfacial waves in horizontal core-annular flow

NASA Astrophysics Data System (ADS)

Tripathi, Sumit; Bhattacharya, Amitabh; Singh, Ramesh; Tabor, Rico F.

2016-11-01

In this work, we characterize interfacial waves in horizontal core annular flow (CAF) of fuel-oil and water. Experimental studies on CAF were performed in an acrylic pipe of 15.5mm internal diameter, and the time evolution of the oil-water interface shape was recorded with a high speed camera for a range of different flow-rates of oil (Qo) and water (Qw). The power spectrum of the interface shape shows a range of notable features. First, there is negligible energy in wavenumbers larger than 2 π / a , where a is the thickness of the annulus. Second, for high Qo /Qw , there is no single dominant wavelength, as the flow in the confined annulus does not allow formation of a preferred mode. Third, for lower Qo /Qw , a dominant mode arises at a wavenumber of 2 π / a . We also observe that the power spectrum of the interface shape depends weakly on Qw, and strongly on Qo, perhaps because the net shear rate in the annulus appears to depend weakly on Qw as well. We also attempt to build a general empirical model for CAF by relating the interfacial stress (calculated via the mean pressure gradient) to the flow rate in the annulus, the annular thickness and the core velocity. Authors are thankful to Orica Mining Services (Australia) for the financial support.

Annulus Fibrosus Can Strip Hyaline Cartilage End Plate from Subchondral Bone: A Study of the Intervertebral Disk in Tension.

PubMed

Balkovec, Christian; Adams, Michael A; Dolan, Patricia; McGill, Stuart M

2015-10-01

Study Design Biomechanical study on cadaveric spines. Objective Spinal bending causes the annulus to pull vertically (axially) on the end plate, but failure mechanisms in response to this type of loading are poorly understood. Therefore, the objective of this study was to identify the weak point of the intervertebral disk in tension. Methods Cadaveric motion segments (aged 79 to 88 years) were dissected to create midsagittal blocks of tissue, with ∼10 mm of bone superior and inferior to the disk. From these blocks, 14 bone-disk-bone slices (average 4.8 mm thick) were cut in the frontal plane. Each slice was gripped by its bony ends and stretched to failure at 1 mm/s. Mode of failure was recorded using a digital camera. Results Of the 14 slices, 10 failed by the hyaline cartilage being peeled off the subchondral bone, with the failure starting opposite the lateral annulus and proceeding medially. Two slices failed by rupturing of the trabecular bone, and a further two failed in the annulus. Conclusions The hyaline cartilage-bone junction is the disk's weak link in tension. These findings provide a plausible mechanism for the appearance of bone and cartilage fragments in herniated material. Stripping cartilage from the bony end plate would result in the herniated mass containing relatively stiff cartilage that does not easily resorb.

Regenerative Blower for EVA Suit Ventilation Fan

NASA Technical Reports Server (NTRS)

Izenson, Michael G.; Chen, Weibo; Paul, Heather L.

2010-01-01

Portable life support systems in future space suits will include a ventilation subsystem driven by a dedicated fan. This ventilation fan must meet challenging requirements for pressure rise, flow rate, efficiency, size, safety, and reliability. This paper describes research and development that showed the feasibility of a regenerative blower that is uniquely suited to meet these requirements. We proved feasibility through component tests, blower tests, and design analysis. Based on the requirements for the Constellation Space Suit Element (CSSE) Portable Life Support System (PLSS) ventilation fan, we designed the critical elements of the blower. We measured the effects of key design parameters on blower performance using separate effects tests, and used the results of these tests to design a regenerative blower that will meet the ventilation fan requirements. We assembled a proof-of-concept blower and measured its performance at sub-atmospheric pressures that simulate a PLSS ventilation loop environment. Head/flow performance and maximum efficiency point data were used to specify the design and operating conditions for the ventilation fan. We identified materials for the blower that will enhance safety for operation in a lunar environment, and produced a solid model that illustrates the final design. The proof-of-concept blower produced the flow rate and pressure rise needed for the CSSE ventilation subsystem while running at 5400 rpm, consuming only 9 W of electric power using a non-optimized, commercial motor and controller and inefficient bearings. Scaling the test results to a complete design shows that a lightweight, compact, reliable, and low power regenerative blower can meet the performance requirements for future space suit life support systems.

Weaning from mechanical ventilation: why are we still looking for alternative methods?

PubMed

Frutos-Vivar, F; Esteban, A

2013-12-01

Most patients who require mechanical ventilation for longer than 24 hours, and who improve the condition leading to the indication of ventilatory support, can be weaned after passing a first spontaneous breathing test. The challenge is to improve the weaning of patients who fail that first test. We have methods that can be referred to as traditional, such as the T-tube, pressure support or synchronized intermittent mandatory ventilation (SIMV). In recent years, however, new applications of usual techniques as noninvasive ventilation, new ventilation methods such as automatic tube compensation (ATC), mandatory minute ventilation (MMV), adaptive support ventilation or automatic weaning systems based on pressure support have been described. Their possible role in weaning from mechanical ventilation among patients with difficult or prolonged weaning remains to be established. Copyright © 2012 Elsevier España, S.L. and SEMICYUC. All rights reserved.

Circuit compliance compensation in lung protective ventilation.

PubMed

Masselli, Grazia Maria Pia; Silvestri, Sergio; Sciuto, Salvatore Andrea; Cappa, Paolo

2006-01-01

Lung protective ventilation utilizes low tidal volumes to ventilate patients with severe lung pathologies. The compensation of breathing circuit effects, i.e. those induced by compressible volume of the circuit, results particularly critical in the calculation of the actual tidal volume delivered to patient's respiratory system which in turns is responsible of the level of permissive hypercapnia. The present work analyzes the applicability of the equation for circuit compressible volume compensation in the case of pressure and volume controlled lung protective ventilation. Experimental tests conducted in-vitro show that the actual tidal volume can be reliably estimated if the compliance of the breathing circuit is measured with the same parameters and ventilation technique that will be utilized in lung protective ventilation. Differences between volume and pressure controlled ventilation are also quantitatively assessed showing that pressure controlled ventilation allows a more reliable compensation of breathing circuit compressible volume.

No Sweat.

ERIC Educational Resources Information Center

Strickland, Gary

2001-01-01

Explains how changes in school design in the last 10 years have caused heating, ventilation, and cooling system (HVAC) designers to reexamine their choice of classroom unit ventilators (UV). The influence of indoor lighting systems, insulation, indoor air quality, energy code compliance, and HVAC system design on UV decision making are also…

Effect of mechanical ventilation on systemic oxygen extraction and lactic acidosis during early septic shock in rats.

PubMed

Griffel, M I; Astiz, M E; Rackow, E C; Weil, M H

1990-01-01

We studied the effect of mechanical ventilation on systemic oxygen extraction and lactic acidosis in peritonitis and shock in rats. Sepsis was induced by cecal ligation and perforation. After tracheostomy, rats were randomized to spontaneous breathing (S) or mechanical ventilation with paralysis (V). Five animals were studied in each group. The V animals were paralyzed with pancuronium bromide to eliminate respiratory effort. Mechanical ventilation consisted of controlled ventilation using a rodent respirator with periodic adjustment of minute ventilation to maintain PaCO2 and pH within normal range. Arterial and central venous blood gases and thermodilution cardiac output were measured at baseline before abdominal surgery, and sequentially at 0.5, 3.5, and 6 h after surgery. At 6 h, cardiac output was 193 +/- 30 ml/kg.min in S animals and 199 +/- 32 ml/kg.min in V animals (NS). The central venous oxygen saturation was 27.4 +/- 4.7% in S animals and 30.0 +/- 6.4% in V animals (NS). Systemic oxygen extraction was 70 +/- 5% in S animals and 67 +/- 6% in V animals (NS). Arterial lactate was 2.4 +/- 0.4 mmol/L in S animals and 2.2 +/- 0.5 mmol/L in V animals (NS). The S animals developed lethal hypotension at 6.6 +/- 0.4 h compared to 6.8 +/- 0.4 h in V animals (NS). These data suggest that mechanical ventilation does not decrease systemic oxygen extraction or ameliorate the development of lactic acidosis during septic shock.

Results from Carbon Dioxide Washout Testing Using a Suited Manikin Test Apparatus with a Space Suit Ventilation Test Loop

NASA Technical Reports Server (NTRS)

Chullen, Cinda; Conger, Bruce; McMillin, Summer; Vonau, Walt; Kanne, Bryan; Korona, Adam; Swickrath, Mike

2016-01-01

NASA is developing an advanced portable life support system (PLSS) to meet the needs of a new NASA advanced space suit. The PLSS is one of the most critical aspects of the space suit providing the necessary oxygen, ventilation, and thermal protection for an astronaut performing a spacewalk. The ventilation subsystem in the PLSS must provide sufficient carbon dioxide (CO2) removal and ensure that the CO2 is washed away from the oronasal region of the astronaut. CO2 washout is a term used to describe the mechanism by which CO2 levels are controlled within the helmet to limit the concentration of CO2 inhaled by the astronaut. Accumulation of CO2 in the helmet or throughout the ventilation loop could cause the suited astronaut to experience hypercapnia (excessive carbon dioxide in the blood). A suited manikin test apparatus (SMTA) integrated with a space suit ventilation test loop was designed, developed, and assembled at NASA in order to experimentally validate adequate CO2 removal throughout the PLSS ventilation subsystem and to quantify CO2 washout performance under various conditions. The test results from this integrated system will be used to validate analytical models and augment human testing. This paper presents the system integration of the PLSS ventilation test loop with the SMTA including the newly developed regenerative Rapid Cycle Amine component used for CO2 removal and tidal breathing capability to emulate the human. The testing and analytical results of the integrated system are presented along with future work.

Measure Guideline: Ventilation Guidance for Residential High-Performance New Construction - Multifamily

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

Lstiburek, Joseph

2017-01-01

The measure guideline provides ventilation guidance for residential high performance multifamily construction that incorporates the requirements of the ASHRAE 62.2 ventilation and indoor air quality standard. The measure guideline focus is on the decision criteria for weighing cost and performance of various ventilation systems. The measure guideline is intended for contractors, builders, developers, designers and building code officials. The guide may also be helpful to building owners wishing to learn more about ventilation strategies available for their buildings. The measure guideline includes specific design and installation instructions for the most cost effective and performance effective solutions for ventilation in multifamilymore » units that satisfies the requirements of ASHRAE 62.2-2016.« less

Measure Guideline: Ventilation Guidance for Residential High-Performance New Construction - Multifamily

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

Lstiburek, Joseph

The measure guideline provides ventilation guidance for residential high performance multifamily construction that incorporates the requirements of the ASHRAE 62.2 ventilation and indoor air quality standard. The measure guideline focus is on the decision criteria for weighing cost and performance of various ventilation systems. The measure guideline is intended for contractors, builders, developers, designers and building code officials. The guide may also be helpful to building owners wishing to learn more about ventilation strategies available for their buildings. The measure guideline includes specific design and installation instructions for the most cost effective and performance effective solutions for ventilation in multifamilymore » units that satisfies the requirements of ASHRAE 62.2-2016.« less

Low-Flow Extracorporeal Carbon Dioxide Removal Using the Hemolung Respiratory Dialysis System® to Facilitate Lung-Protective Mechanical Ventilation in Acute Respiratory Distress Syndrome.

PubMed

Akkanti, Bindu; Rajagopal, Keshava; Patel, Kirti P; Aravind, Sangeeta; Nunez-Centanu, Emmanuel; Hussain, Rahat; Shabari, Farshad Raissi; Hofstetter, Wayne L; Vaporciyan, Ara A; Banjac, Igor S; Kar, Biswajit; Gregoric, Igor D; Loyalka, Pranav

2017-06-01

Extracorporeal carbon dioxide removal (ECCO 2 R) permits reductions in alveolar ventilation requirements that the lungs would otherwise have to provide. This concept was applied to a case of hypercapnia refractory to high-level invasive mechanical ventilator support. We present a case of an 18-year-old man who developed post-pneumonectomy acute respiratory distress syndrome (ARDS) after resection of a mediastinal germ cell tumor involving the left lung hilum. Hypercapnia and hypoxemia persisted despite ventilator support even at traumatic levels. ECCO 2 R using a miniaturized system was instituted and provided effective carbon dioxide elimination. This facilitated establishment of lung-protective ventilator settings and lung function recovery. Extracorporeal lung support increasingly is being applied to treat ARDS. However, conventional extracorporeal membrane oxygenation (ECMO) generally involves using large cannulae capable of carrying high flow rates. A subset of patients with ARDS has mixed hypercapnia and hypoxemia despite high-level ventilator support. In the absence of profound hypoxemia, ECCO 2 R may be used to reduce ventilator support requirements to lung-protective levels, while avoiding risks associated with conventional ECMO.

The impact of particle filtration on indoor air quality in a classroom near a highway.

PubMed

van der Zee, S C; Strak, M; Dijkema, M B A; Brunekreef, B; Janssen, N A H

2017-03-01

A pilot study was performed to investigate whether the application of a new mechanical ventilation system with a fine F8 (MERV14) filter could improve indoor air quality in a high school near the Amsterdam ring road. PM10, PM2.5, and black carbon (BC) concentrations were measured continuously inside an occupied intervention classroom and outside the school during three sampling periods in the winter of 2013/2014. Initially, 3 weeks of baseline measurements were performed, with the existing ventilation system and normal ventilation habits. Next, an intervention study was performed. A new ventilation system was installed in the classroom, and measurements were performed during 8 school weeks, in alternating 2-week periods with and without the filter in the ventilation system under otherwise identical ventilation conditions. Indoor/outdoor ratios measured during the weeks with filter were compared with those measured without filter to evaluate the ability of the F8 filter to improve indoor air quality. During teaching hours, the filter reduced BC exposure by, on average, 36%. For PM10 and PM2.5, a reduction of 34% and 30% was found, respectively. This implies that application of a fine filter can reduce the exposure of schoolchildren to traffic exhaust at hot spot locations by about one-third. © 2016 The Authors. Indoor Air published by John Wiley & Sons Ltd.

[Monitorization of respiratory mechanics in the ventilated patient].

PubMed

García-Prieto, E; Amado-Rodríguez, L; Albaiceta, G M

2014-01-01

Monitoring during mechanical ventilation allows the measurement of different parameters of respiratory mechanics. Accurate interpretation of these data can be useful for characterizing the situation of the different components of the respiratory system, and for guiding ventilator settings. In this review, we describe the basic concepts of respiratory mechanics, their interpretation, and their potential use in fine-tuning mechanical ventilation. Copyright © 2013 Elsevier España, S.L. y SEMICYUC. All rights reserved.

The correlation of Acanthamoeba from the ventilation system with other environmental parameters in commercial buildings as possible indicator for indoor air quality.

PubMed

Ooi, Soo Shen; Mak, Joon Wah; Chen, Donald K F; Ambu, Stephen

2017-02-07

The free-living protozoan Acanthamoeba is an opportunistic pathogen that is ubiquitous in our environment. However, its role in affecting indoor air quality and ill-health of indoor occupants is relatively unknown. The present study investigated the presence of Acanthamoeba from the ventilation system and its correlation with other indoor air quality parameters, used in the industry code of practice and its potential as an indicator for indoor air quality. Indoor air quality assessments were carried out in nine commercial buildings with approval from the building management, and the parameters assessed were as recommended by the Department of Occupational Safety and Health. The presence of Acanthamoeba was determined through dust swabs from the ventilation system and indoor furniture. Logistic regression was performed to study the correlation between assessed parameters and occupants' complaints. A total of 107 sampling points were assessed and 40.2% of the supplying air diffuser and blowing fan and 15% of the furniture were positive for cysts. There was a significant correlation between Acanthamoeba detected from the ventilation system with ambient total fungus count (r=0.327; p=0.01) and respirable particulates (r=0.276; p=0.01). Occupants' sick building syndrome experience also correlated with the presence of Acanthamoeba in the ventilation system (r=0.361; p=0.01) and those detected on the furniture (r=0.290; p=0.01). Logistic regression showed that there was a five-fold probability of sick building syndrome among occupants when Acanthamoeba was detected in the ventilation system.

The correlation of Acanthamoeba from the ventilation system with other environmental parameters in commercial buildings as possible indicator for indoor air quality

PubMed Central

OOI, Soo Shen; MAK, Joon Wah; CHEN, Donald K.F.; AMBU, Stephen

2016-01-01

The free-living protozoan Acanthamoeba is an opportunistic pathogen that is ubiquitous in our environment. However, its role in affecting indoor air quality and ill-health of indoor occupants is relatively unknown. The present study investigated the presence of Acanthamoeba from the ventilation system and its correlation with other indoor air quality parameters, used in the industry code of practice and its potential as an indicator for indoor air quality. Indoor air quality assessments were carried out in nine commercial buildings with approval from the building management, and the parameters assessed were as recommended by the Department of Occupational Safety and Health. The presence of Acanthamoeba was determined through dust swabs from the ventilation system and indoor furniture. Logistic regression was performed to study the correlation between assessed parameters and occupants’ complaints. A total of 107 sampling points were assessed and 40.2% of the supplying air diffuser and blowing fan and 15% of the furniture were positive for cysts. There was a significant correlation between Acanthamoeba detected from the ventilation system with ambient total fungus count (r=0.327; p=0.01) and respirable particulates (r=0.276; p=0.01). Occupants’ sick building syndrome experience also correlated with the presence of Acanthamoeba in the ventilation system (r=0.361; p=0.01) and those detected on the furniture (r=0.290; p=0.01). Logistic regression showed that there was a five-fold probability of sick building syndrome among occupants when Acanthamoeba was detected in the ventilation system. PMID:27476379

Analysis on ventilation pressure of fire area in longitudinal ventilation of underground tunnel

NASA Astrophysics Data System (ADS)

Li, Jiaxin; Li, Yanfeng; Feng, Xiao; Li, Junmei

2018-03-01

In order to solve the problem of ventilation pressure loss in the fire area under the fire condition, the wind pressure loss model of the fire area is established based on the thermodynamic equilibrium relation. The semi-empirical calculation formula is obtained by using the model experiment and CFD simulation. The validity of the formula is verified. The results show that the ventilation pressure loss in the fire zone is proportional to the convective heat release rate at the critical velocity, which is inversely proportional to the upstream ventilation velocity and the tunnel cross-sectional area. The proposed formula is consistent with the law of the tunnel fire test fitting formula that results are close, in contrast, the advantage lies in a clear theoretical basis and ventilation velocity values. The resistance of road tunnel ventilation system is calculated accurately and reliably, and then an effective emergency ventilation operation program is developed. It is necessary to consider the fire zone ventilation pressure loss. The proposed ventilation pressure loss formula can be used for design calculation after thorough verification.

Effects of light ingress through ventilation fan apertures on selected blood variables of male broilers

USDA-ARS?s Scientific Manuscript database

Increasing broiler house size and ventilation capacity have resulted in increased light ingress through ventilation system component apertures. The effective photoperiod for broilers may create local increases in light intensity, which may also impact broiler’ body homeostasis. The objective of this...

30 CFR 75.326 - Mean entry air velocity.

Code of Federal Regulations, 2013 CFR

2013-07-01

... exhausting face ventilation systems, the mean entry air velocity shall be at least 60 feet per minute reaching each working face where coal is being cut, mined, drilled for blasting, or loaded, and to any... the inby end of the line curtain, ventilation tubing, or other face ventilation control devices. [61...

30 CFR 75.326 - Mean entry air velocity.

Code of Federal Regulations, 2011 CFR

2011-07-01

... exhausting face ventilation systems, the mean entry air velocity shall be at least 60 feet per minute reaching each working face where coal is being cut, mined, drilled for blasting, or loaded, and to any... the inby end of the line curtain, ventilation tubing, or other face ventilation control devices. [61...

30 CFR 75.326 - Mean entry air velocity.

Code of Federal Regulations, 2010 CFR

2010-07-01

... exhausting face ventilation systems, the mean entry air velocity shall be at least 60 feet per minute reaching each working face where coal is being cut, mined, drilled for blasting, or loaded, and to any... the inby end of the line curtain, ventilation tubing, or other face ventilation control devices. [61...

Effect of Ventilation Strategies on Residential Ozone Levels

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

Walker, Iain S.; Sherman, Max H.

Elevated outdoor ozone levels are associated with adverse health effects. Because people spend the vast majority of their time indoors, reduction in indoor levels of ozone of outdoor origin would lower population exposures and might also lead to a reduction in ozone-associated adverse health effects. In most buildings, indoor ozone levels are diminished with respect to outdoor levels to an extent that depends on surface reactions and on the degree to which ozone penetrates the building envelope. Ozone enters buildings from outdoors together with the airflows that are driven by natural and mechanical means, including deliberate ventilation used to reducemore » concentrations of indoor-generated pollutants. When assessing the effect of deliberate ventilation on occupant health one should consider not only the positive effects on removing pollutants of indoor origin but also the possibility that enhanced ventilation might increase indoor levels of pollutants originating outdoors. This study considers how changes in residential ventilation that are designed to comply with ASHRAE Standard 62.2 might influence indoor levels of ozone. Simulation results show that the building envelope can contribute significantly to filtration of ozone. Consequently, the use of exhaust ventilation systems is predicted to produce lower indoor ozone concentrations than would occur with balanced ventilation systems operating at the same air-­exchange rate. We also investigated a strategy for reducing exposure to ozone that would deliberately reduce ventilation rates during times of high outdoor ozone concentration while still meeting daily average ventilation requirements.« less

Energy and cost associated with ventilating office buildings in a tropical climate.

PubMed

Rim, Donghyun; Schiavon, Stefano; Nazaroff, William W

2015-01-01

Providing sufficient amounts of outdoor air to occupants is a critical building function for supporting occupant health, well-being and productivity. In tropical climates, high ventilation rates require substantial amounts of energy to cool and dehumidify supply air. This study evaluates the energy consumption and associated cost for thermally conditioning outdoor air provided for building ventilation in tropical climates, considering Singapore as an example locale. We investigated the influence on energy consumption and cost of the following factors: outdoor air temperature and humidity, ventilation rate (L/s per person), indoor air temperature and humidity, air conditioning system coefficient of performance (COP), and cost of electricity. Results show that dehumidification of outdoor air accounts for more than 80% of the energy needed for building ventilation in Singapore's tropical climate. Improved system performance and/or a small increase in the indoor temperature set point would permit relatively large ventilation rates (such as 25 L/s per person) at modest or no cost increment. Overall, even in a thermally demanding tropical climate, the energy cost associated with increasing ventilation rate up to 25 L/s per person is less than 1% of the wages of an office worker in an advanced economy like Singapore's. This result implies that the benefits of increasing outdoor air ventilation rate up to 25 L/s per person--which is suggested to provide for productivity increases, lower sick building syndrome symptom prevalence, and reduced sick leave--can be much larger than the incremental cost of ventilation.

Water supply rates for recirculating evaporative cooling systems in poultry housing

USDA-ARS?s Scientific Manuscript database

Evaporative cooling (EC) is an important tool to reduce heat stress in animal housing systems. Expansion of ventilation capacity in tunnel ventilated poultry facilities has resulted in increased water demand for EC systems. As water resources become more limited and costly, proper planning and des...

77 FR 16869 - Proposed Models for Plant-Specific Adoption of Technical Specifications Task Force Traveler TSTF...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-03-22

... Ventilation System Surveillance Requirements to Operate for 10 hours per Month.'' DATES: Comment period....1, which currently require operating the heaters in the respective systems for at least 10... Adoption of Technical Specifications Task Force Traveler TSTF-522, Revision 0, ``Revise Ventilation System...

Usefulness of Tricuspid Annular Diameter to Predict Late Right Sided Heart Failure in Patients With Left Ventricular Assist Device.

PubMed

Nakanishi, Koki; Homma, Shunichi; Han, Jiho; Takayama, Hiroo; Colombo, Paolo C; Yuzefpolskaya, Melana; Garan, Arthur R; Farr, Maryjane A; Kurlansky, Paul; Di Tullio, Marco R; Naka, Yoshifumi; Takeda, Koji

2018-07-01

Although late-onset right-sided heart failure is recognized as a clinical problem in the treatment of patients with left ventricular assist devices (LVADs), the mechanism and predictors are unknown. Tricuspid valve (TV) deformation leads to the restriction of the leaflet motion and decreased coaptation, resulting in a functional tricuspid regurgitation that may act as a surrogate marker of late right-sided heart failure. This study aimed to investigate the association of preoperative TV deformation (annulus dilatation and leaflet tethering) with late right-sided heart failure development after continuous-flow LVAD implantation. The study cohort consisted of 274 patients who underwent 2-dimensional echocardiography before LVAD implantation. TV annulus diameter and tethering distance were measured in an apical 4-chamber view. Late right-sided heart failure was defined as right-sided heart failure requiring readmission and medical and/or surgical treatment after initial LVAD implantation. During a mean follow-up of 25.1 ± 19.0 months after LVAD implantation, late right-sided heart failure occurred in 33 patients (12.0%). Multivariate Cox proportional hazard analysis demonstrated that TV annulus diameter (hazard ratio 1.221 per 1 mm, p <0.001) was significantly associated with late right-sided heart failure development, whereas leaflet tethering distance was not. The best cut-off value of the TV annular diameter was 41 mm (area under the curve 0.787). Kaplan-Meier analysis showed that patients with dilated TV annulus (TV annular diameter ≥41 mm) exhibited a significantly higher late right-sided heart failure occurrence than those without TV annular enlargement (log-rank p <0.001). In conclusion, preoperative TV annulus diameter, but not leaflet tethering distance, predicted the occurrence of late right-sided heart failure after LVAD implantation. Copyright © 2018 Elsevier Inc. All rights reserved.

Evaluation of a new 3-dimensional color Doppler flow method to quantify flow across the mitral valve and in the left ventricular outflow tract: an in vitro study.

PubMed

Kimura, Sumito; Streiff, Cole; Zhu, Meihua; Shimada, Eriko; Datta, Saurabh; Ashraf, Muhammad; Sahn, David J

2014-02-01

The aim of this study was to assess the accuracy, feasibility, and reproducibility of determining stroke volume from a novel 3-dimensional (3D) color Doppler flow quantification method for mitral valve (MV) inflow and left ventricular outflow tract (LVOT) outflow at different stroke volumes when compared with the actual flow rate in a pumped porcine cardiac model. Thirteen freshly harvested pig hearts were studied in a water tank. We inserted a latex balloon into each left ventricle from the MV annulus to the LVOT, which were passively pumped at different stroke volumes (30-80 mL) using a calibrated piston pump at increments of 10 mL. Four-dimensional flow volumes were obtained without electrocardiographic gating. The digital imaging data were analyzed offline using prototype software. Two hemispheric flow-sampling planes for color Doppler velocity measurements were placed at the MV annulus and LVOT. The software computed the flow volumes at the MV annulus and LVOT within the user-defined volume and cardiac cycle. This novel 3D Doppler flow quantification method detected incremental increases in MV inflow and LVOT outflow in close agreement with pumped stroke volumes (MV inflow, r = 0.96; LVOT outflow, r = 0.96; P < .01). Bland-Altman analysis demonstrated overestimation of both (MV inflow, 5.42 mL; LVOT outflow, 4.46 mL) with 95% of points within 95% limits of agreement. Interobserver variability values showed good agreement for all stroke volumes at both the MV annulus and LVOT. This study has shown that the 3D color Doppler flow quantification method we used is able to compute stroke volumes accurately at the MV annulus and LVOT in the same cardiac cycle without electrocardiographic gating. This method may be valuable for assessment of cardiac output in clinical studies.

Quantity and location of aortic valve complex calcification predicts severity and location of paravalvular regurgitation and frequency of post-dilation after balloon-expandable transcatheter aortic valve replacement.

PubMed

Khalique, Omar K; Hahn, Rebecca T; Gada, Hemal; Nazif, Tamim M; Vahl, Torsten P; George, Isaac; Kalesan, Bindu; Forster, Molly; Williams, Mathew B; Leon, Martin B; Einstein, Andrew J; Pulerwitz, Todd C; Pearson, Gregory D N; Kodali, Susheel K

2014-08-01

This study sought to determine the impact of quantity and location of aortic valve calcification (AVC) on paravalvular regurgitation (PVR) and rates of post-dilation (PD) immediately after transcatheter aortic valve replacement (TAVR). The impact of AVC in different locations within the aortic valve complex is incompletely understood. This study analyzed 150 patients with severe, symptomatic aortic stenosis who underwent TAVR. Total AVC volume scores were calculated from contrast-enhanced multidetector row computed tomography imaging. AVC was divided by leaflet sector and region (Leaflet, Annulus, left ventricular outflow tract [LVOT]), and a combination of LVOT and Annulus (AnnulusLVOT). Asymmetry was assessed. Receiver-operating characteristic analysis was performed with greater than or equal to mild PVR and PD as classification variables. Logistic regression was performed. Quantity of and asymmetry of AVC for all regions of the aortic valve complex predicted greater than or equal to mild PVR by receiver-operating characteristic analysis (area under the curve = 0.635 to 0.689), except Leaflet asymmetry. Receiver-operating characteristic analysis for PD was significant for quantity and asymmetry of AVC in all regions, with higher area under the curve values than for PVR (area under the curve = 0.648 to 0.741). On multivariable analysis, Leaflet and AnnulusLVOT calcification were independent predictors of both PVR and PD regardless of multidetector row computed tomography area cover index. Quantity and asymmetry of AVC in all regions of the aortic valve complex predict greater than or equal to mild PVR and performance of PD, with the exception of Leaflet asymmetry. Quantity of AnnulusLVOT and Leaflet calcification independently predict PVR and PD when taking into account multidetector row computed tomography area cover index. Copyright © 2014 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Optimal prosthesis sizing in transcatheter aortic valve implantation by exclusive use of three-dimensional transoesophageal echocardiography.

PubMed

Kretzschmar, Daniel; Lauten, Alexander; Goebel, Bjoern; Doenst, Torsten; Poerner, Tudor C; Ferrari, Markus; Figulla, Hans R; Hamadanchi, Ali

2016-03-01

The assessment of aortic annular size is critical, and inappropriate sizing is thought to be a main reason of paravalvular aortic regurgitation. Multidetector computed tomograph is associated with the risk of contrast nephropathy. For optimal evaluation of the complex structure of the aortic annulus, three-dimensional (3D)-methods should be used. We therefore sought to determine the value of 3D-transoesophageal echocardiography (3D-TEE) for appropriate sizing. Hundred and one patients (mean age 81·4 years) with symptomatic aortic valve stenosis (AS) and high surgical risk profile (mean log. EuroScore 28·8%) being scheduled for transcatheter aortic valve implantation (TAVI) were included. 2D- and 3D-TEE were performed before the procedure to evaluate the aortic annulus diameter. Maximum, minimum and mean (max diameter + min diameter/2) annulus diameters were 24·7, 23·1 and 23. 9 mm in 3D-TEE and compared to 22·6 mm in 2D-TEE (P<0·001; 0·07; <0·001). The interobserver variability for 3D-TEE was low with a mean difference of 0·18 mm compared to 2D-TEE with 0·59 mm. The application of 3D-TEE caused a change of prosthesis size selection in 40% of patients compared to 2D-TEE. In this study, we implanted three different types of catheter-mounted valves (Edwards-SAPIEN(™) XT valve, CoreValve(™) and JenaValve(™) ). Final angiography confirmed valve competence (mild insufficiency) in 91%, and there was no aortic regurgitation greater than moderate in the follow-up echocardiographic evaluation. Assessment of aortic annulus dimensions for TAVI size selection can safely be performed with 3D-TEE only. Based on our results with significantly higher annulus diameter compared to 2D-TEE, we recommend 3D-TEE to reduce prosthesis undersizing. © 2014 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

[Formaldehyde-reducing efficiency of a newly developed dissection-table-connected local ventilation system in the gross anatomy laboratory room].

PubMed

Shinoda, Koh; Oba, Jun

2010-03-01

In compliance with health and safety management guidelines against harmful formaldehyde (FA) levels in the gross anatomy laboratory, we newly developed a dissection-table-connected local ventilation system in 2006. The system was composed of (1) a simple plenum-chambered dissection table with low-cost filters, (2) a transparent vinyl flexible duct for easy mounting and removal, which connects the table and the exhaust pipe laid above the ceiling, and (3) an intake creating a downward-flow of air, which was installed on the ceiling just above each table. The dissection table was also designed as a separate-component system, of which the upper plate and marginal suction inlets can be taken apart for cleaning after dissection, and equipped with opening/closing side-windows for picking up materials dropped during dissection and a container underneath the table to receive exudate from the cadaver through a waste-fluid pipe. The local ventilation system dramatically reduced FA levels to 0.01-0.03 ppm in the gross anatomy laboratory room, resulting in no discomforting FA smell and irritating sensation while preserving the student's view of room and line of flow as well as solving the problems of high maintenance cost, sanitation issues inside the table, and working-inconvenience during dissection practice. Switching ventilation methods or power-modes, the current local ventilation system was demonstrated to be more than ten times efficient in FA reduction compared to the whole-room ventilation system and suggested that 11 m3/min/table in exhaust volume should decrease FA levels in both A- and B-measurements to less than 0.1 ppm in 1000 m3 space containing thirty-one 3.5%-FA-fixed cadavers.

Unsteady Reynolds-averaged Navier-Stokes simulations of inlet distortion in the fan system of a gas-turbine aero-engine

NASA Astrophysics Data System (ADS)

Spotts, Nathan

As modern trends in commercial aircraft design move toward high-bypass-ratio fan systems of increasing diameter with shorter, nonaxisymmetric nacelle geometries, inlet distortion is becoming common in all operating regimes. The distortion may induce aerodynamic instabilities within the fan system, leading to catastrophic damage to fan blades, should the surge margin be exceeded. Even in the absence of system instability, the heterogeneity of the flow affects aerodynamic performance significantly. Therefore, an understanding of fan-distortion interaction is critical to aircraft engine system design. This thesis research elucidates the complex fluid dynamics and fan-distortion interaction by means of computational fluid dynamics (CFD) modeling of a complete engine fan system; including rotor, stator, spinner, nacelle and nozzle; under conditions typical of those encountered by commercial aircraft. The CFD simulations, based on a Reynolds-averaged Navier-Stokes (RANS) approach, were unsteady, three-dimensional, and of a full-annulus geometry. A thorough, systematic validation has been performed for configurations from a single passage of a rotor to a full-annulus system by comparing the predicted flow characteristics and aerodynamic performance to those found in literature. The original contributions of this research include the integration of a complete engine fan system, based on the NASA rotor 67 transonic stage and representative of the propulsion systems in commercial aircraft, and a benchmark case for unsteady RANS simulations of distorted flow in such a geometry under realistic operating conditions. This study is unique in that the complex flow dynamics, resulting from fan-distortion interaction, were illustrated in a practical geometry under realistic operating conditions. For example, the compressive stage is shown to influence upstream static pressure distributions and thus suppress separation of flow on the nacelle. Knowledge of such flow physics is valuable for engine system design.

A Systems Approach to High Performance Buildings: A Computational Systems Engineering R&D Program to Increase DoD Energy Efficiency

DTIC Science & Technology

2012-02-01

for Low Energy Building Ventilation and Space Conditioning Systems...Building Energy Models ................... 162 APPENDIX D: Reduced-Order Modeling and Control Design for Low Energy Building Systems .... 172 D.1...Design for Low Energy Building Ventilation and Space Conditioning Systems This section focuses on the modeling and control of airflow in buildings

Universal fuel basket for use with an improved oxide reduction vessel and electrorefiner vessel

DOEpatents

Herrmann, Steven D.; Mariani, Robert D.

2002-01-01

A basket, for use in the reduction of UO.sub.2 to uranium metal and in the electrorefining of uranium metal, having a continuous annulus between inner and outer perforated cylindrical walls, with a screen adjacent to each wall. A substantially solid bottom and top plate enclose the continuous annulus defining a fuel bed. A plurality of scrapers are mounted adjacent to the outer wall extending longitudinally thereof, and there is a mechanism enabling the basket to be transported remotely.

Performance of transonic fan stage with weight flow per unit annulus area of 208 kilograms per second per square meter (42.6 (lb/sec)/sq ft)

NASA Technical Reports Server (NTRS)

Urasek, D. C.; Kovich, G.; Moore, R. D.

1973-01-01

Performance was obtained for a 50-cm-diameter compressor designed for a high weight flow per unit annulus area of 208 (kg/sec)/sq m. Peak efficiency values of 0.83 and 0.79 were obtained for the rotor and stage, respectively. The stall margin for the stage was 23 percent, based on equivalent weight flow and total-pressure ratio at peak efficiency and stall.

Horizontal baffle for nuclear reactors

DOEpatents

Rylatt, John A.

1978-01-01

A horizontal baffle disposed in the annulus defined between the core barrel and the thermal liner of a nuclear reactor thereby physically separating the outlet region of the core from the annular area below the horizontal baffle. The horizontal baffle prevents hot coolant that has passed through the reactor core from thermally damaging apparatus located in the annulus below the horizontal baffle by utilizing the thermally induced bowing of the horizontal baffle to enhance sealing while accommodating lateral motion of the baffle base plate.

46 CFR 105.25-7 - Ventilation systems for cargo tank or pumping system compartment.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 4 2010-10-01 2010-10-01 false Ventilation systems for cargo tank or pumping system compartment. 105.25-7 Section 105.25-7 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CARGO AND MISCELLANEOUS VESSELS COMMERCIAL FISHING VESSELS DISPENSING PETROLEUM PRODUCTS Additional Requirements-When Cargo Tanks Are Installed...

46 CFR 108.437 - Pipe sizes and discharge rates for enclosed ventilation systems for rotating electrical equipment.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 4 2010-10-01 2010-10-01 false Pipe sizes and discharge rates for enclosed ventilation systems for rotating electrical equipment. 108.437 Section 108.437 Shipping COAST GUARD, DEPARTMENT OF... Systems Fixed Carbon Dioxide Fire Extinguishing Systems § 108.437 Pipe sizes and discharge rates for...

SITE TECHNOLOGY CAPSULE: SUBSURFACE VOLATILIZATION AND VENTILATION SYSTEM (SVVS)

EPA Science Inventory

The Subsurface Volatilization and Ventilation System is an integrated technology used for attacking all phases of volatile organic compound (VOC) contamination in soil and groundwater. The SVVS technology promotes insitu remediation of soil and groundwater contaminated with or-ga...

Magnetic Resonance Imaging of Ventilation and Perfusion in the Lung

NASA Technical Reports Server (NTRS)

Prisk, Gordon Kim (Inventor); Hopkins, Susan Roberta (Inventor); Pereira De Sa, Rui Carlos (Inventor); Theilmann, Rebecca Jean (Inventor); Buxton, Richard Bruce (Inventor); Cronin, Matthew Vincent (Inventor)

2017-01-01

Methods, devices, and systems are disclosed for implementing a fully quantitative non-injectable contrast proton MRI technique to measure spatial ventilation-perfusion (VA/Q) matching and spatial distribution of ventilation and perfusion. In one aspect, a method using MRI to characterize ventilation and perfusion in a lung includes acquiring an MR image of the lung having MR data in a voxel and obtaining a breathing frequency parameter, determining a water density value, a specific ventilation value, and a perfusion value in at least one voxel of the MR image based on the MR data and using the water density value to determine an air content value, and determining a ventilation-perfusion ratio value that is the product of the specific ventilation value, the air content value, the inverse of the perfusion value, and the breathing frequency.

Symmetry-breaking Hopf bifurcations to 1-, 2-, and 3-tori in small-aspect-ratio counterrotating Taylor-Couette flow.

PubMed

Altmeyer, S; Do, Y; Marques, F; Lopez, J M

2012-10-01

The nonlinear dynamics of Taylor-Couette flow in a small-aspect-ratio wide-gap annulus in the counterrotating regime is investigated by solving the full three-dimensional Navier-Stokes equations. The system is invariant under arbitrary rotations about the axis, reflection about the annulus midplane, and time translations. A systematic investigation is presented both in terms of the flow physics elucidated from the numerical simulations and from a dynamical system perspective provided by equivariant normal form theory. The dynamics are primarily associated with the behavior of the jet of angular momentum that emerges from the inner cylinder boundary layer at about the midplane. The sequence of bifurcations as the differential rotation is increased consists of an axisymmetric Hopf bifurcation breaking the reflection symmetry of the basic state leading to an axisymmetric limit cycle with a half-period-flip spatiotemporal symmetry. This undergoes a Hopf bifurcation breaking axisymmetry, leading to quasiperiodic solutions evolving on a 2-torus that is setwise symmetric. These undergo a further Hopf bifurcation, introducing a third incommensurate frequency leading to a 3-torus that is also setwise symmetric. On the 3-torus, as the differential rotation is further increased, a saddle-node-invariant-circle bifurcation takes place, destroying the 3-torus and leaving a pair of symmetrically related 2-tori states on which all symmetries of the system have been broken.

Signal source optimization of visible light communication for communication equality

NASA Astrophysics Data System (ADS)

Yun, Liu; Wen, Shangsheng; Xie, Canyu; Chen, Yincong

2018-03-01

Square and circular light source layouts conventionally employed in visible light communication (VLC) systems suffer from communication blind spots and received signal nonuniformity as well as from large power fluctuations in the middle of the room. To address these shortcomings, we use the cross square and annulus layouts in conjunction with the cross-fertilize particle swarm optimization algorithm to improve VLC system performance. The distribution of the unit area received power (RPUA), the distribution of the signal-to-noise ratio (SNR), and the bit error rate (BER) performance were simulated and the rationality of the algorithm was compared. The results show that after optimization, the RPUA fluctuation value of the cross square layout decreases from 2.32 to 1.59 dB / m2, the SNR fluctuation value reduces from 8.5 to 4.2 dB, and the RPUA fluctuation value of the annulus layout decreases from 4.69 to 3.46 dB / m2, the SNR fluctuation value decreases from 13.3 to 8.8 dB. The RPUA value of cross-square layout fluctuates between -1.5 and -0.5 dB / m2, and the receiving area accounts for 93.4% in this range while in the case of the square layout, this area is only 86.7%. Therefore, it suggests that this scheme is reasonable for the equality of communication quality and system performance heightens greatly.

6. VIEW LOOKING SOUTHEAST AT VENTILATION EQUIPMENT IN SOUTH VENTILATION ...

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

6. VIEW LOOKING SOUTHEAST AT VENTILATION EQUIPMENT IN SOUTH VENTILATION HOUSE. THIS AIR CONDITIONING SYSTEM WAS INSTALLED BY PARKS-CRAMER COMPANY OF FITCHBURG, MASSACHUSETTS WHEN THE MILL WAS CONSTRUCTED IN 1923-24. ONE AIR WASHER AND FAN ROOM EXTERIOR IS VISIBLE ON THE RIGHT. THE DUCTS FROM BOTH FAN ROOMS (CURVED METAL STRUCTURES AT CENTER AND LEFT OF PHOTO) ARE CONNECTED TO A COMMON AIR SHAFT. - Stark Mill, 117 Corinth Road, Hogansville, Troup County, GA

In-depth survey report: Assisting furniture strippers in reducing the risk from methylene chloride stripping formulations at Los Angeles Stripping and Refinishing Center, Los Angeles, California

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

Estill, C.F.; Kovein, R.J.; Jones, J.H.

1999-03-26

The National Institute for Occupational Safety and Health (NIOSH) is currently conducting research on ventilation controls to reduce furniture stripping exposures to methylene chloride to the OSHA PEL of 25 ppm. Low cost ventilation systems were designed by NIOSH researchers along with Benny Bixenman of Benco Sales, Inc. (Forney, TX). The controls were constructed and installed by Benco Sales. This report compares the methylene chloride levels of one worker stripping furniture using the recently installed ventilation controls and using the existing controls. During the survey, two different chemical stripping solutions (a standard formulation and a low methylene chloride content formulation)more » were used and compared. This survey tested three control combinations: (1) new ventilation, low methylene chloride stripper, (2) new ventilation, standard stripping solution, and (3) old ventilation, standard stripping solution. During each test, sorbent tube sampling and real-time sampling were employed. Sorbent tube, data collected in the worker's breathing zone, ranged from 300 to 387 ppm. Real-time data showed breathing zone exposures to range from 211 to 383 ppm while stripping and 164 to 230 ppm while rinsing. Data were inconclusive to determine which ventilation system or stripping solution produced the lowest exposures. Recommendations are made in the report to improve the newly installed ventilation controls.« less

Full-Scale Schlieren Visualization of Commercial Kitchen Ventilation Aerodynamics

NASA Astrophysics Data System (ADS)

Miller, J. D.; Settles, G. S.

1996-11-01

The efficient removal of cooking effluents from commercial kitchens has been identified as the most pressing energy-related issue in the food service industry. A full-scale schlieren optical system with a 2.1x2.7m field-of-view, described at previous APS/DFD meetings, images the convective airflow associated with a typical gas-fired cooking griddle and ventilation hood. Previous attempts to visualize plumes from cooking equipment by smoke and neutrally-buoyant bubbles were not sufficiently keyed to thermal convection. Here, the point where the ventilation hood fails to capture the effluent plume is clearly visible, thus determining the boundary condition for a balanced ventilation system. Further, the strong influence of turbulent entrainment is seen in the behavior of the combustion products vented by the griddle and the interference caused by a makeup-air outlet located too close to the lip of the ventilation hood. Such applications of traditional fluid dynamics techniques and principles are believed to be important to the maturing of ventilation technology. (Research supported by EPRI and IFMA, Inc.)

Modeled Effectiveness of Ventilation with Contaminant Control Devices on Indoor Air Quality in a Swine Farrowing Facility

PubMed Central

Anthony, T. Renée; Altmaier, Ralph; Park, Jae Hong; Peters, Thomas M.

2016-01-01

Because adverse health effects experienced by swine farm workers in concentrated animal feeding operations (CAFOs) have been associated with exposure to dust and gases, efforts to reduce exposures are warranted, particularly in winter seasons when exposures increase due to decreased ventilation. Simulation of air quality and operating costs for ventilating swine CAFO, including treating and recirculating air through a farrowing room, was performed using mass and energy balance equations over a 90-day winter season. System operation required controlling heater operation to achieve room temperatures optimal to ensure animal health (20 to 22.5°C). Five air pollution control devices, four room ventilation rates, and five recirculation patterns were examined. Inhalable dust concentrations were easily reduced using standard industrial air pollution control devices, including a cyclone, filtration, and electrostatic precipitator. Operating ventilation systems at 0.94 m3 s−1 (2000 cfm) with 75 to 100% recirculation of treated air from cyclone, electrostatic precipitator, and shaker dust filtration system achieves adequate particle control with operating costs under $1.00 per pig produced ($0.22 to 0.54), although carbon dioxide (CO2) concentrations approach 2000 ppm using in-room ventilated gas fired heaters. In no simulation were CO2 concentrations below industry recommended concentrations (1540 ppm), but alternative heating devices could reduce CO2 to acceptable concentrations. While this investigation does not represent all production swine farrowing barns, which differ in characteristics including room dimensions and swine occupancy, the simulation model and ventilation optimization methods can be applied to other production sites. This work shows that ventilation may be a cost-effective control option in the swine industry to reduce exposures. PMID:24433305

Modeled effectiveness of ventilation with contaminant control devices on indoor air quality in a swine farrowing facility.

PubMed

Anthony, T Renée; Altmaier, Ralph; Park, Jae Hong; Peters, Thomas M

2014-01-01

Because adverse health effects experienced by swine farm workers in concentrated animal feeding operations (CAFOs) have been associated with exposure to dust and gases, efforts to reduce exposures are warranted, particularly in winter seasons when exposures increase due to decreased ventilation. Simulation of air quality and operating costs for ventilating swine CAFO, including treating and recirculating air through a farrowing room, was performed using mass and energy balance equations over a 90-day winter season. System operation required controlling heater operation to achieve room temperatures optimal to ensure animal health (20 to 22.5 °C). Five air pollution control devices, four room ventilation rates, and five recirculation patterns were examined. Inhalable dust concentrations were easily reduced using standard industrial air pollution control devices, including a cyclone, filtration, and electrostatic precipitator. Operating ventilation systems at 0.94 m3 s(-1) (2000 cfm) with 75 to 100% recirculation of treated air from cyclone, electrostatic precipitator, and shaker dust filtration system achieves adequate particle control with operating costs under $1.00 per pig produced ($0.22 to 0.54), although carbon dioxide (CO2) concentrations approach 2000 ppm using in-room ventilated gas fired heaters. In no simulation were CO2 concentrations below industry recommended concentrations (1540 ppm), but alternative heating devices could reduce CO2 to acceptable concentrations. While this investigation does not represent all production swine farrowing barns, which differ in characteristics including room dimensions and swine occupancy, the simulation model and ventilation optimization methods can be applied to other production sites. This work shows that ventilation may be a cost-effective control option in the swine industry to reduce exposures.

Ventilation, temperature, and HVAC characteristics in small and medium commercial buildings in California.

PubMed

Bennett, D H; Fisk, W; Apte, M G; Wu, X; Trout, A; Faulkner, D; Sullivan, D

2012-08-01

This field study of 37 small and medium commercial buildings throughout California obtained information on ventilation rate, temperature, and heating, ventilating, and air-conditioning (HVAC) system characteristics. The study included seven retail establishments; five restaurants; eight offices; two each of gas stations, hair salons, healthcare facilities, grocery stores, dental offices, and fitness centers; and five other buildings. Fourteen (38%) of the buildings either could not or did not provide outdoor air through the HVAC system. The air exchange rate averaged 1.6 (s.d. = 1.7) exchanges per hour and was similar between buildings with and without outdoor air supplied through the HVAC system, indicating that some buildings have significant leakage or ventilation through open windows and doors. Not all buildings had sufficient air exchange to meet ASHRAE 62.1 Standards, including buildings used for fitness centers, hair salons, offices, and retail establishments. The majority of the time, buildings were within the ASHRAE temperature comfort range. Offices were frequently overcooled in the summer. All of the buildings had filters, but over half the buildings had a filter with a minimum efficiency reporting value rating of 4 or lower, which are not very effective for removing fine particles. Most U.S. commercial buildings (96%) are small- to medium-sized, using nearly 18% of the country's energy, and sheltering a large population daily. Little is known about the ventilation systems in these buildings. This study found a wide variety of ventilation conditions, with many buildings failing to meet relevant ventilation standards. Regulators may want to consider implementing more complete building inspections at commissioning and point of sale. © 2012 John Wiley & Sons A/S.

Technology evaluation of heating, ventilation, and air conditioning for MIUS application

NASA Technical Reports Server (NTRS)

Gill, W. L.; Keough, M. B.; Rippey, J. O.

1974-01-01

Potential ways of providing heating, ventilation, and air conditioning for a building complex serviced by a modular integrated utility system (MIUS) are examined. Literature surveys were conducted to investigate both conventional and unusual systems to serve this purpose. The advantages and disadvantages of the systems most compatible with MIUS are discussed.

40 CFR 98.323 - Calculating GHG emissions.

Code of Federal Regulations, 2012 CFR

2012-07-01

...: ER12JY10.005 Where: CH4VTotal = Total quarterly CH4 liberated from ventilation systems (metric tons CH4... and degasification systems, calculated using Equation FF-6 of this section (metric tons). (e) For the... vent holes are collected, you must calculate the quarterly CH4 liberated from the ventilation system...

40 CFR 98.323 - Calculating GHG emissions.

Code of Federal Regulations, 2013 CFR

2013-07-01

...: ER12JY10.005 Where: CH4VTotal = Total quarterly CH4 liberated from ventilation systems (metric tons CH4... and degasification systems, calculated using Equation FF-6 of this section (metric tons). (e) For the... vent holes are collected, you must calculate the quarterly CH4 liberated from the ventilation system...

Are tidal volume measurements in neonatal pressure-controlled ventilation accurate?

PubMed

Chow, Lily C; Vanderhal, Andre; Raber, Jorge; Sola, Augusto

2002-09-01

Bedside pulmonary mechanics monitors (PMM) have become useful in ventilatory management in neonates. These monitors are used more frequently due to recent improvements in data-processing capabilities. PMM devices are often part of the ventilator or are separate units. The accuracy and reliability of these systems have not been carefully evaluated. We compared a single ventilatory parameter, tidal volume (V(t)), as measured by several systems. We looked at two freestanding PMMs: the Ventrak Respiratory Monitoring System (Novametrix, Wallingford, CT) and the Bicore CP-100 Neonatal Pulmonary Monitor (Allied Health Care Products, Riverside, CA), and three ventilators with built-in PMM: the VIP Bird Ventilator (Bird Products Corp., Palm Springs, CA), Siemens Servo 300A (Siemens-Elema AB, Solna, Sweden), and Drager Babylog 8000 (Drager, Inc., Chantilly, VA). A calibrated syringe (Hans Rudolph, Inc., Kansas City, MO) was used to deliver tidal volumes of 4, 10, and 20 mL to each ventilator system coupled with a freestanding PMM. After achieving steady state, six consecutive V(t) readings were taken simultaneously from the freestanding PMM and each ventilator. In a second portion of the bench study, we used pressure-control ventilation and measured exhaled tidal volume (V(te)) while ventilating a Bear Test Lung with the same three ventilators. We adjusted peak inspiratory pressure (PIP) under controlled conditions to achieve the three different targeted tidal volumes on the paired freestanding PMM. Again, six V(te) measurements were recorded for each tidal volume. Means and standard deviations were calculated.The percentage difference in measurement of V(t) delivered by calibrated syringe varied greatly, with the greatest discrepancy seen in the smallest tidal volumes, by up to 28%. In pressure control mode, V(te) as measured by the Siemens was significantly overestimated by 20-95%, with the biggest discrepancy at the smallest V(te), particularly when paired with the Bicore PMM. V(te), as measured by the VIP Bird and Drager paired with the Ventrak PMM, had a tendency to underestimate V(t) by up to 25% at the smallest V(te). However, when paired with the Bicore PMM, these same two ventilators read over target by up to 18%. Under controlled laboratory conditions, we demonstrated that true delivered V(te), as measured by the three ventilators and two freestanding PMM, differed markedly. In general, decreasing dynamic compliance of the tubing was not associated with greater inaccuracy in V(te) measurements. Copyright 2002 Wiley-Liss, Inc.

Semiempirical method of determining flow coefficients for pitot rake mass flow rate measurements

NASA Technical Reports Server (NTRS)

Trefny, C. J.

1985-01-01

Flow coefficients applicable to area-weighted pitot rake mass flow rate measurements are presented for fully developed, turbulent flow in an annulus. A turbulent velocity profile is generated semiempirically for a given annulus hub-to-tip radius ratio and integrated numerically to determine the ideal mass flow rate. The calculated velocities at each probe location are then summed, and the flow rate as indicated by the rake is obtained. The flow coefficient to be used with the particular rake geometry is subsequently obtained by dividing the ideal flow rate by the rake-indicated flow rate. Flow coefficients ranged from 0.903 for one probe placed at a radius dividing two equal areas to 0.984 for a 10-probe area-weighted rake. Flow coefficients were not a strong function of annulus hub-to-tip radius ratio for rakes with three or more probes. The semiempirical method used to generate the turbulent velocity profiles is described in detail.

Variations on Debris Disks. IV. An Improved Analytical Model for Collisional Cascades

NASA Astrophysics Data System (ADS)

Kenyon, Scott J.; Bromley, Benjamin C.

2017-04-01

We derive a new analytical model for the evolution of a collisional cascade in a thin annulus around a single central star. In this model, r max the size of the largest object changes with time, {r}\\max \\propto {t}-γ , with γ ≈ 0.1-0.2. Compared to standard models where r max is constant in time, this evolution results in a more rapid decline of M d , the total mass of solids in the annulus, and L d , the luminosity of small particles in the annulus: {M}d\\propto {t}-(γ +1) and {L}d\\propto {t}-(γ /2+1). We demonstrate that the analytical model provides an excellent match to a comprehensive suite of numerical coagulation simulations for annuli at 1 au and at 25 au. If the evolution of real debris disks follows the predictions of the analytical or numerical models, the observed luminosities for evolved stars require up to a factor of two more mass than predicted by previous analytical models.

Slow deformation of intervertebral discs.

PubMed

Broberg, K B

1993-01-01

Intervertebral discs exhibit pronounced time-dependent deformations when subjected to load variations. These deformations are caused by fluid flow to and from the disc and by viscoelastic deformation of annulus fibres. The fluid flow is caused by differences between mechanical and osmotic pressure. A mechanical model of lumbar disc functions allows one to calculate both the extent of fluid flow and its implications for disc height as well as the role played by viscoelastic deformation of annulus fibres. From such calculations changes in body height are estimated. Experimental results already documented in the literature offer bases for the determination of the parameters involved. Body height variations are studied, both those related to normal diurnal rhythmicity and those related to somewhat exceptional circumstances. The normal diurnal fluid flow is found to be about +/- 40% of the disc fluid content late in the evening. Viscoelastic deformation of annulus fibres contributes approximately one quarter of the height change obtained after several hours normal activity, but dominates during the first hour.

Experimental study using ER-YAG laser in discs: changes in glycosaminoglycan content and synthesis in discs

NASA Astrophysics Data System (ADS)

Maehara, Kazuyuki; Nakai, Sadaaki; Naga, Kumi; Nishimoto, Seiji

2004-09-01

Changes in discs after Er-Yag laser irradiation are scarcely reported. We made an experimental study using white rabbits and Er-Yag laser. Under general anesthesia, Er-Yag laser was irradiated into lumbar discs. Three or 8 weeks after irradiation, rabbits were sacrificed, and these discs were extracted. The quantitative analysis of the glycosaminoglycan content in the annulus fibrosus, and the incorporation of 35S-sulfate in chondroitin 4 sulfate were measured. The results showed, the increased incorporation of 35S-sulfate in chondroitin 4 sulfate and chondroitin 6 sulfates in groups of laser irradiation may indicate Er-Yag laser irradiation in nucleus pulposus, accelerated glycosaminoglycan production, in the annulus fibrosus. But no difference of unsaturated isomers of chondroitin 4 sulfate, and chondroitin 6 sulfate, and no difference of saturated isomer of keratan sulfate indicate, the influence of Er-Yag laser irradiation was not so high, as to bring the quantitative changes of matrix of annulus fibrosus in term of 8 weeks.

Combustor with multistage internal vortices

DOEpatents

Shang, Jer Yu; Harrington, R.E.

1987-05-01

A fluidized bed combustor is provided with a multistage arrangement of vortex generators in the freeboard area. The vortex generators are provided by nozzle means which extend into the interior of the freeboard for forming vortices within the freeboard areas to enhance the combustion of particulate material entrained in product gases ascending into the freeboard from the fluidized bed. Each of the nozzles are radially inwardly spaced from the combustor walls defining the freeboard to provide for the formation of an essentially vortex-free, vertically extending annulus about the vortices whereby the particulate material centrifuged from the vortices against the inner walls of the combustor is returned through the annulus to the fluidized bed. By adjusting the vortex pattern within the freeboard, a significant portion of the full cross-sectional area of the freeboard except for the peripheral annulus can be contacted with the turbulent vortical flow for removing the particulate material from the gaseous products and also for enhancing the combustion thereof within the freeboard. 2 figs.

Combustor with multistage internal vortices

DOEpatents

Shang, Jer Y.; Harrington, Richard E.

1989-01-01

A fluidized bed combustor is provided with a multistage arrangement of vortex generators in the freeboard area. The vortex generators are provided by nozzle means which extend into the interior of the freeboard for forming vortices within the freeboard area to enhance the combustion of particulate material entrained in product gases ascending into the freeboard from the fluidized bed. Each of the nozzles are radially inwardly spaced from the combustor walls defining the freeboard to provide for the formation of an essentially vortex-free, vertically extending annulus about the vortices whereby the particulate material centrifuged from the vortices against the inner walls of the combustor is returned through the annulus to the fluidized bed. By adjusting the vortex pattern within the freeboard, a significant portion of the full cross-sectional area of the freeboard except for the peripheral annulus can be contacted with the turbulent vortical flow for removing the particulate material from the gaseous products and also for enhancing the combustion thereof within the freeboard.

Space-charge-limited currents for cathodes with electric field enhanced geometry

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

Lai, Dingguo, E-mail: laidingguo@nint.ac.cn; Qiu, Mengtong; Xu, Qifu

This paper presents the approximate analytic solutions of current density for annulus and circle cathodes. The current densities of annulus and circle cathodes are derived approximately from first principles, which are in agreement with simulation results. The large scaling laws can predict current densities of high current vacuum diodes including annulus and circle cathodes in practical applications. In order to discuss the relationship between current density and electric field on cathode surface, the existing analytical solutions of currents for concentric cylinder and sphere diodes are fitted from existing solutions relating with electric field enhancement factors. It is found that themore » space-charge-limited current density for the cathode with electric-field enhanced geometry can be written in a general form of J = g(β{sub E}){sup 2}J{sub 0}, where J{sub 0} is the classical (1D) Child-Langmuir current density, β{sub E} is the electric field enhancement factor, and g is the geometrical correction factor depending on the cathode geometry.« less

A comparison of the clinical, haemodynamic and angiographic features in right ventricular endomyocardial fibrosis and Ebstein's anomaly of the tricuspid valve.

PubMed

Balakrishnan, K G; Sapru, R P; Sasidharan, K; Venkitachalam, C G

1982-01-01

The clinical, haemodynamic and angiographic features of 18 patients with right ventricular endomyocardial fibrosis (RVEMF) and 8 patients with Ebstein's anomaly of the tricuspid valve (EATV) have been compared. Diagnosis was confirmed by selective angiography. The position of the tricuspid annulus was identified from selective right ventricular angiograms and confirmed by selective right coronary angiography. In 83% of RVEMF patients the tricuspid annulus was displaced to the left of the spine. A false impression of displacement of the tricuspid leaflet can thus be created. However, a tricuspid leaflet displaced away from the tricuspid annulus was found only in patients with EATV. A considerable overlap exists between the wide spectrum of clinical presentations of the two conditions. Helpful distinguishing features that favour EATV were, the presence of a scratchy diastolic murmur and polyphasic QRS complexes in the ECG. Atrial fibrillation in the ECG, and myocardial calcification or pericardial effusion, whenever present, favour RVEMF.

Two-phase magnetoconvection flow of magnetite (Fe3O4) nanoparticles in a horizontal composite porous annulus

NASA Astrophysics Data System (ADS)

Abbas, Zaheer; Hasnain, Jafar

A numerical study is performed to examine the two-phase magnetoconvection and heat transfer phenomena of Fe3O4 -kerosene nanofluid flow in a horizontal composite porous annulus with an external magnetic field. The annulus is filled with immiscible fluids flowing between two concentric cylinders. The governing equations of the flow problem are obtained using Darcy-Brinkman model. Heat transfer is analyzed in the presence of viscous and Darcian dissipation terms. The shooting method is used as a tool to solve the obtained non-linear ordinary differential equations for the velocity and temperature profiles. The velocity and temperature distributions are analyzed and discussed under the influence of involved flow parameters with the aid of graphs. It is found that both velocity and temperature of fluid are decreased with ferroparticle volume fraction. In addition to that, it is also presented that the existence of magnetic field decreases the benefit of ferrofluids in heat transfer progression.

Phase retrieval in annulus sector domain by non-iterative methods

NASA Astrophysics Data System (ADS)

Wang, Xiao; Mao, Heng; Zhao, Da-zun

2008-03-01

Phase retrieval could be achieved by solving the intensity transport equation (ITE) under the paraxial approximation. For the case of uniform illumination, Neumann boundary condition is involved and it makes the solving process more complicated. The primary mirror is usually designed segmented in the telescope with large aperture, and the shape of a segmented piece is often like an annulus sector. Accordingly, It is necessary to analyze the phase retrieval in the annulus sector domain. Two non-iterative methods are considered for recovering the phase. The matrix method is based on the decomposition of the solution into a series of orthogonalized polynomials, while the frequency filtering method depends on the inverse computation process of ITE. By the simulation, it is found that both methods can eliminate the effect of Neumann boundary condition, save a lot of computation time and recover the distorted phase well. The wavefront error (WFE) RMS can be less than 0.05 wavelength, even when some noise is added.

Evaluation of manual and automatic manually triggered ventilation performance and ergonomics using a simulation model.

PubMed

Marjanovic, Nicolas; Le Floch, Soizig; Jaffrelot, Morgan; L'Her, Erwan

2014-05-01

In the absence of endotracheal intubation, the manual bag-valve-mask (BVM) is the most frequently used ventilation technique during resuscitation. The efficiency of other devices has been poorly studied. The bench-test study described here was designed to evaluate the effectiveness of an automatic, manually triggered system, and to compare it with manual BVM ventilation. A respiratory system bench model was assembled using a lung simulator connected to a manikin to simulate a patient with unprotected airways. Fifty health-care providers from different professional groups (emergency physicians, residents, advanced paramedics, nurses, and paramedics; n = 10 per group) evaluated manual BVM ventilation, and compared it with an automatic manually triggered device (EasyCPR). Three pathological situations were simulated (restrictive, obstructive, normal). Standard ventilation parameters were recorded; the ergonomics of the system were assessed by the health-care professionals using a standard numerical scale once the recordings were completed. The tidal volume fell within the standard range (400-600 mL) for 25.6% of breaths (0.6-45 breaths) using manual BVM ventilation, and for 28.6% of breaths (0.3-80 breaths) using the automatic manually triggered device (EasyCPR) (P < .0002). Peak inspiratory airway pressure was lower using the automatic manually triggered device (EasyCPR) (10.6 ± 5 vs 15.9 ± 10 cm H2O, P < .001). The ventilation rate fell consistently within the guidelines, in the case of the automatic manually triggered device (EasyCPR) only (10.3 ± 2 vs 17.6 ± 6, P < .001). Significant pulmonary overdistention was observed when using the manual BVM device during the normal and obstructive sequences. The nurses and paramedics considered the ergonomics of the automatic manually triggered device (EasyCPR) to be better than those of the manual device. The use of an automatic manually triggered device may improve ventilation efficiency and decrease the risk of pulmonary overdistention, while decreasing the ventilation rate.

Variable tidal volumes improve lung protective ventilation strategies in experimental lung injury.

PubMed

Spieth, Peter M; Carvalho, Alysson R; Pelosi, Paolo; Hoehn, Catharina; Meissner, Christoph; Kasper, Michael; Hübler, Matthias; von Neindorff, Matthias; Dassow, Constanze; Barrenschee, Martina; Uhlig, Stefan; Koch, Thea; de Abreu, Marcelo Gama

2009-04-15

Noisy ventilation with variable Vt may improve respiratory function in acute lung injury. To determine the impact of noisy ventilation on respiratory function and its biological effects on lung parenchyma compared with conventional protective mechanical ventilation strategies. In a porcine surfactant depletion model of lung injury, we randomly combined noisy ventilation with the ARDS Network protocol or the open lung approach (n = 9 per group). Respiratory mechanics, gas exchange, and distribution of pulmonary blood flow were measured at intervals over a 6-hour period. Postmortem, lung tissue was analyzed to determine histological damage, mechanical stress, and inflammation. We found that, at comparable minute ventilation, noisy ventilation (1) improved arterial oxygenation and reduced mean inspiratory peak airway pressure and elastance of the respiratory system compared with the ARDS Network protocol and the open lung approach, (2) redistributed pulmonary blood flow to caudal zones compared with the ARDS Network protocol and to peripheral ones compared with the open lung approach, (3) reduced histological damage in comparison to both protective ventilation strategies, and (4) did not increase lung inflammation or mechanical stress. Noisy ventilation with variable Vt and fixed respiratory frequency improves respiratory function and reduces histological damage compared with standard protective ventilation strategies.

Energy and Cost Associated with Ventilating Office Buildings in a Tropical Climate

PubMed Central

Rim, Donghyun; Schiavon, Stefano; Nazaroff, William W.

2015-01-01

Providing sufficient amounts of outdoor air to occupants is a critical building function for supporting occupant health, well-being and productivity. In tropical climates, high ventilation rates require substantial amounts of energy to cool and dehumidify supply air. This study evaluates the energy consumption and associated cost for thermally conditioning outdoor air provided for building ventilation in tropical climates, considering Singapore as an example locale. We investigated the influence on energy consumption and cost of the following factors: outdoor air temperature and humidity, ventilation rate (L/s per person), indoor air temperature and humidity, air conditioning system coefficient of performance (COP), and cost of electricity. Results show that dehumidification of outdoor air accounts for more than 80% of the energy needed for building ventilation in Singapore’s tropical climate. Improved system performance and/or a small increase in the indoor temperature set point would permit relatively large ventilation rates (such as 25 L/s per person) at modest or no cost increment. Overall, even in a thermally demanding tropical climate, the energy cost associated with increasing ventilation rate up to 25 L/s per person is less than 1% of the wages of an office worker in an advanced economy like Singapore’s. This result implies that the benefits of increasing outdoor air ventilation rate up to 25 L/s per person — which is suggested to provide for productivity increases, lower sick building syndrome symptom prevalence, and reduced sick leave — can be much larger than the incremental cost of ventilation. PMID:25822504

Contribution of the administrative database and the geographical information system to disaster preparedness and regionalization.

PubMed

Kuwabara, Kazuaki; Matsuda, Shinya; Fushimi, Kiyohide; Ishikawa, Koichi B; Horiguchi, Hiromasa; Fujimori, Kenji

2012-01-01

Public health emergencies like earthquakes and tsunamis underscore the need for an evidence-based approach to disaster preparedness. Using the Japanese administrative database and the geographical information system (GIS), the interruption of hospital-based mechanical ventilation administration by a hypothetical disaster in three areas of the southeastern mainland (Tokai, Tonankai, and Nankai) was simulated and the repercussions on ventilator care in the prefectures adjacent to the damaged prefectures was estimated. Using the database of 2010 including 3,181,847 hospitalized patients among 952 hospitals, the maximum daily ventilator capacity in each hospital was calculated and the number of patients who were administered ventilation on October xx was counted. Using GIS and patient zip code, the straight-line distances among the damaged hospitals, the hospitals in prefectures nearest to damaged prefectures, and ventilated patients' zip codes were measured. The authors simulated that ventilated patients were transferred to the closest hospitals outside damaged prefectures. The increase in the ventilator operating rates in three areas was aggregated. One hundred twenty-four and 236 patients were administered ventilation in the damaged hospitals and in the closest hospitals outside the damaged prefectures of Tokai, 92 and 561 of Tonankai, and 35 and 85 of Nankai, respectively. The increases in the ventilator operating rates among prefectures ranged from 1.04 to 26.33-fold in Tokai; 1.03 to 1.74-fold in Tonankai, and 1.00 to 2.67-fold in Nankai. Administrative databases and GIS can contribute to evidenced-based disaster preparedness and the determination of appropriate receiving hospitals with available medical resources.

Evidence of inadequate ventilation in portable classrooms: results of a pilot study in Los Angeles County.

PubMed

Shendell, D G; Winer, A M; Weker, R; Colome, S D

2004-06-01

The prevalence of prefabricated, portable classrooms (portables) for United States public schools has increased; in California, approximately one of three students learn inside portables. Limited research has been conducted on indoor air and environmental quality in American schools, and almost none in portables. Available reports and conference proceedings suggest problems from insufficient ventilation due to poor design, operation, and/or maintenance of heating, ventilation and air conditioning (HVAC) systems; most portables have one mechanical, wall-mounted HVAC system. A pilot assessment was conducted in Los Angeles County, including measurements of integrated ventilation rates based on a perfluorocarbon tracer gas technique and continuous monitoring of temperature (T) and relative humidity (RH). Measured ventilation rates were low [mean school day integrated average 0.8 per hour (range: 0.1-2.9 per hour)]. Compared with relevant standards, results suggested adequate ventilation and associated conditioning of indoor air for occupant comfort were not always provided to these classrooms. Future school studies should include integrated and continuous measurements of T, RH, and ventilation with appropriate tracer gas methods, and other airflow measures. Adequate ventilation has the potential to mitigate concentrations of chemical pollutants, particles, carbon dioxide, and odors in portable and traditional classrooms, which should lead to a reduction in reported health outcomes, e.g., symptoms of 'sick building syndrome', allergies, asthma. Investigations of school indoor air and environmental quality should include continuous temperature and relative humidity data with inexpensive instrumentation as indicators of thermal comfort, and techniques to measure ventilation rates.

Decommissioning of Active Ventilation Systems in a Nuclear R and D Facility to Prepare for Building Demolition (Whiteshell Laboratories Decommissioning Project, Canada) - 13073

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

Wilcox, Brian; May, Doug; Howlett, Don

2013-07-01

Whiteshell Laboratories (WL) is a nuclear research establishment owned by the Canadian government and operated by Atomic Energy of Canada Limited (AECL) since the early 1960's. WL is currently under a decommissioning license and the mandate is to remediate the nuclear legacy liabilities in a safe and cost effective manner. The WL Project is the first major nuclear decommissioning project in Canada. A major initiative underway is to decommission and demolish the main R and D Laboratory complex. The Building 300 R and D complex was constructed to accommodate laboratories and offices which were mainly used for research and developmentmore » associated with organic-cooled reactors, nuclear fuel waste management, reactor safety, advanced fuel cycles and other applications of nuclear energy. Building 300 is a three storey structure of approximately 16,000 m{sup 2}. In order to proceed with building demolition, the contaminated systems inside the building have to be characterized, removed, and the waste managed. There is a significant focus on volume reduction of radioactive waste for the WL project. The active ventilation system is one of the significant contaminated systems in Building 300 that requires decommissioning and removal. The active ventilation system was designed to manage hazardous fumes and radioactivity from ventilation devices (e.g., fume hoods, snorkels and glove boxes) and to prevent the escape of airborne hazardous material outside of the laboratory boundary in the event of an upset condition. The system includes over 200 ventilation devices and 32 active exhaust fan units and high efficiency particulate air (HEPA) filters. The strategy to remove the ventilation system was to work from the laboratory end back to the fan/filter system. Each ventilation duct was radiologically characterized. Fogging was used to minimize loose contamination. Sections of the duct were removed by various cutting methods and bagged for temporary storage prior to disposition. Maintenance of building heating, ventilation and air conditioning (HVAC) balancing was critical to ensure proper airflow and worker safety. Approximately 103 m{sup 3} of equipment and materials were recovered or generated by the project. Low level waste accounted for approximately 37.4 m{sup 3}. Where possible, ducting was free released for metal recycling. Contaminated ducts were compacted into B-1000 containers and stored in a Shielded Modular Above-Ground Storage Facility (SMAGS) on the WL site awaiting final disposition. The project is divided into three significant phases, with Phases 1 and 2 completed. Lessons learned during the execution of Phases 1 and 2 have been incorporated into the current ventilation removal. (authors)« less

Methods to reduce the CO(2) concentration of educational buildings utilizing internal ventilation by transferred air.

PubMed

Kalema, T; Viot, M

2014-02-01

The aim of this study is to develop internal ventilation by transferred air to achieve a good indoor climate with low energy consumption in educational buildings with constant air volume (CAV) ventilation. Both measurements of CO2 concentration and a multi-room calculation model are presented. The study analyzes how to use more efficiently the available spaces and the capacity of CAV ventilation systems in existing buildings and the impact this has on the indoor air quality and the energy consumption of the ventilation. The temperature differences can be used to create natural ventilation airflows between neighboring spaces. The behavior of temperature-driven airflows between rooms was studied and included in the calculation model. The effect of openings between neighboring spaces, such as doors or large apertures in the walls, on the CO2 concentration was studied in different classrooms. The air temperatures and CO2 concentrations were measured using a wireless, internet-based measurement system. The multi-room calculation model predicted the CO2 concentration in the rooms, which was then compared with the measured ones. Using transferred air between occupied and unoccupied spaces can noticeably reduce the total mechanical ventilation rates needed to keep a low CO2 concentration. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Proportional mechanical ventilation through PWM driven on/off solenoid valve.

PubMed

Sardellitti, I; Cecchini, S; Silvestri, S; Caldwell, D G

2010-01-01

Proportional strategies for artificial ventilation are the most recent form of synchronized partial ventilatory assistance and intra-breath control techniques available in clinical practice. Currently, the majority of commercial ventilators allowing proportional ventilation uses proportional valves to generate the flow rate pattern. This paper proposes on-off solenoid valves for proportional ventilation given their small size, low cost and short switching time, useful for supplying high frequency ventilation. A new system based on a novel fast switching driver circuit combined with on/off solenoid valve is developed. The average short response time typical of onoff solenoid valves was further reduced through the driving circuit for the implementation of PWM control. Experimental trials were conducted for identifying the dynamic response of the PWM driven on/off valve and for verifying its effectiveness in generating variable-shaped ventilatory flow rate patterns. The system was able to smoothly follow the reference flow rate patterns also changing in time intervals as short as 20 ms, achieving a flow rate resolution up to 1 L/min and repeatability in the order of 0.5 L/min. Preliminary results showed the feasibility of developing a stand alone portable device able to generate both proportional and high frequency ventilation by only using on-off solenoid valves.

Do submesoscale frontal processes ventilate the oxygen minimum zone off Peru?

NASA Astrophysics Data System (ADS)

Thomsen, S.; Kanzow, T.; Colas, F.; Echevin, V.; Krahmann, G.; Engel, A.

2016-08-01

The Peruvian upwelling system encompasses the most intense and shallowest oxygen minimum zone (OMZ) in the ocean. This system shows pronounced submesoscale activity like filaments and fronts. We carried out glider-based observations off Peru during austral summer 2013 to investigate whether submesoscale frontal processes ventilate the Peruvian OMZ. We present observational evidence for the subduction of highly oxygenated surface water in a submesoscale cold filament. The subduction event ventilates the oxycline but does not reach OMZ core waters. In a regional submesoscale-permitting model we study the pathways of newly upwelled water. About 50% of upwelled virtual floats are subducted below the mixed layer within 5 days emphasizing a hitherto unrecognized importance of subduction for the ventilation of the Peruvian oxycline.

Detonation propagation in annular arcs of condensed phase explosives

NASA Astrophysics Data System (ADS)

Ioannou, Eleftherios; Schoch, Stefan; Nikiforakis, Nikolaos; Michael, Louisa

2017-11-01

We present a numerical study of detonation propagation in unconfined explosive charges shaped as an annular arc (rib). Steady detonation in a straight charge propagates at constant speed, but when it enters an annular section, it goes through a transition phase and eventually reaches a new steady state of constant angular velocity. This study examines the speed of the detonation wave along the annular charge during the transition phase and at steady state, as well as its dependence on the dimensions of the annulus. The system is modeled using a recently proposed diffuse-interface formulation which allows for the representation of a two-phase explosive and of an additional inert material. The explosive considered is the polymer-bonded TATB-based LX-17 and is modeled using two Jones-Wilkins-Lee (JWL) equations of state and the ignition and growth reaction rate law. Results show that steady state speeds are in good agreement with experiment. In the transition phase, the evolution of outer detonation speed deviates from the exponential bounded growth function suggested by previous studies. We propose a new description of the transition phase which consists of two regimes. The first regime is caused by local effects at the outer edge of the annulus and leads to a dependence of the outer detonation speed on the angular position along the arc. The second regime is induced by effects originating from the inner edge of the annular charge and leads to the deceleration of the outer detonation until steady state is reached. The study concludes with a parametric study where the dependence of the steady state and the transition phase on the dimensions of the annulus is investigated.

A novel finite element model of the ovine lumbar intervertebral disc with anisotropic hyperelastic material properties

PubMed Central

Galbusera, Fabio; Jonas, René; Schlager, Benedikt; Wilke, Hans-Joachim; Villa, Tomaso

2017-01-01

The Ovine spine is an accepted model to investigate the biomechanical behaviour of the human lumbar one. Indeed, the use of animal models for in vitro studies is necessary to investigate the mechanical behaviour of biological tissue, but needs to be reduced for ethical and social reasons. The aim of this study was to create a finite element model of the lumbar intervertebral disc of the sheep that may help to refine the understanding of parallel in vitro experiments and that can be used to predict when mechanical failure occurs. Anisotropic hyperelastic material properties were assigned to the annulus fibrosus and factorial optimization analyses were performed to find out the optimal parameters of the ground substance and of the collagen fibers. For the ground substance of the annulus fibrosus the investigation was based on experimental data taken from the literature, while for the collagen fibers tensile tests on annulus specimens were conducted. Flexibility analysis in flexion-extension, lateral bending and axial rotation were conducted. Different material properties for the anterior, lateral and posterior regions of the annulus were found. The posterior part resulted the stiffest region in compression whereas the anterior one the stiffest region in tension. Since the flexibility outcomes were in a good agreement with the literature data, we considered this model suitable to be used in conjunction with in vitro and in vivo tests to investigate the mechanical behaviour of the ovine lumbar disc. PMID:28472100

Intercellular communication via gap junctions affected by mechanical load in the bovine annulus fibrosus.

PubMed

Desrochers, Jane; Duncan, Neil A

2014-01-01

Cells in the intervertebral disc, as in other connective tissues including tendon, ligament and bone, form interconnected cellular networks that are linked via functional gap junctions. These cellular networks may be necessary to affect a coordinated response to mechanical and environmental stimuli. Using confocal microscopy with fluorescence recovery after photobleaching methods, we explored the in situ strain environment of the outer annulus of an intact bovine disc and the effect of high-level flexion on gap junction signalling. The in situ strain environment in the extracellular matrix of the outer annulus under high flexion load was observed to be non-uniform with the extensive cellular processes remaining crimped sometimes at flexion angles greater than 25°. A significant transient disruption of intercellular communication via functional gap junctions was measured after 10 and 20 min under high flexion load. This study illustrates that in healthy annulus fibrosus tissue, high mechanical loads can impede the functioning of the gap junctions. Future studies will explore more complex loading conditions to determine whether losses in intercellular communication can be permanent and whether gap junctions in aged and degenerated tissues become more susceptible to load. The current research suggests that cellular structures such as gap junctions and intercellular networks, as well as other cell-cell and cell-matrix interconnections, need to be considered in computational models in order to fully understand how macroscale mechanical signals are transmitted across scales to the microscale and ultimately into a cellular biosynthetic response in collagenous tissues.

Control rod driveline and grapple

DOEpatents

Germer, John H.

1987-01-01

A control rod driveline and grapple is disclosed for placement between a control rod drive and a nuclear reactor control rod containing poison for parasitic neutron absorption required for reactor shutdown. The control rod is provided with an enlarged cylindrical handle which terminates in an upwardly extending rod to provide a grapple point for the driveline. The grapple mechanism includes a tension rod which receives the upwardly extending handle and is provided with a lower annular flange. A plurality of preferably six grapple segments surround and grip the control rod handle. Each grapple rod segment grips the flange on the tension rod at an interior upper annular indentation, bears against the enlarged cylindrical handle at an intermediate annulus and captures the upwardly flaring frustum shaped handle at a lower and complementary female segment. The tension rods and grapple segments are surrounded by and encased within a cylinder. The cylinder terminates immediately and outward extending annulus at the lower portion of the grapple segments. Excursion of the tension rod relative to the encasing cylinder causes rod release at the handle by permitting the grapple segments to pivot outwardly and about the annulus on the tension rod so as to open the lower defined frustum shaped annulus and drop the rod. Relative movement between the tension rod and cylinder can occur either due to electromagnetic release of the tension rod within defined limits of travel or differential thermal expansion as between the tension rod and cylinder as where the reactor exceeds design thermal limits.

Annulus formation on scales of four species of coregonids reared under artificial conditions

USGS Publications Warehouse

Hogman, Walter J.

1968-01-01

Scales from known-age coregonids reared in the laboratory were examined to determine when annuli formed and to learn possible factors of their formation. Scales were taken monthly from marked fish for periods up to 21 months. Scales were also examined from fish that died and from preserved specimens of young-of-the-year for each species. Two marks formed on almost all scales each calender year. The stronger formed during March-April and the weaker in October-November. Both marks had all the usual characteristics of an annulus but the spring mark was considered the annulus and the fall mark an accessory check. The annulus formed during a period of constant temperatures and of little change in growth or increasing growth. The accessory check formed during a period of declining temperatures (1-5 degrees F, or 0.6-2.8 degrees C, per month) and of little change in growth or declining growth. Most fish grew throughout the winter; the only exceptions were one bloater (Coregonus hoyi) and several of the largest lake whitefish (C. clupeaformis). Fish were always given all the food they would eat to eliminate availability of food as a factor of mark formation. The temperature of the water during the winter (50 ±. 0.3 F; 10.0 ±. 0.2 C) did not arrest metabolic activity. The growth rate was related more closely to day length than to other variables examined.

Modeling interlamellar interactions in angle-ply biologic laminates for annulus fibrosus tissue engineering

PubMed Central

Nerurkar, Nandan L.; Mauck, Robert L.

2012-01-01

Mechanical function of the annulus fibrosus of the intervertebral disc is dictated by the composition and microstructure of its highly ordered extracellular matrix. Recent work on engineered angle-ply laminates formed from mesenchymal stem cell (MSC)-seeded nanofibrous scaffolds indicates that the organization of collagen fibers into planes of alternating alignment may play an important role in annulus fibrosus tissue function. Specifically, these engineered tissues can resist tensile deformation through shearing of the interlamellar matrix as layers of collagen differentially reorient under load. In the present work, a hyperelastic constitutive model was developed to describe the role of interlamellar shearing in reinforcing the tensile response of biologic laminates, and was applied to experimental results from engineered annulus constructs formed from MSC-seeded nanofibrous scaffolds. By applying the constitutive model to uniaxial tensile stress–strain data for bilayers with three different fiber orientations, material parameters were generated that characterize the contributions of extrafibrillar matrix, fibers, and interlamellar shearing interactions. By 10 weeks of in vitro culture, interlamellar shearing accounted for nearly 50% of the total stress associated with uniaxial extension in the anatomic range of ply angle. The model successfully captured changes in function with extracellular matrix deposition through variations in the magnitude of model parameters with culture duration. This work illustrates the value of engineered tissues as tools to further our understanding of structure–function relations in native tissues and as a test-bed for the development of constitutive models to describe them. PMID:21287395

Modeling interlamellar interactions in angle-ply biologic laminates for annulus fibrosus tissue engineering.

PubMed

Nerurkar, Nandan L; Mauck, Robert L; Elliott, Dawn M

2011-12-01

Mechanical function of the annulus fibrosus of the intervertebral disc is dictated by the composition and microstructure of its highly ordered extracellular matrix. Recent work on engineered angle-ply laminates formed from mesenchymal stem cell (MSC)-seeded nanofibrous scaffolds indicates that the organization of collagen fibers into planes of alternating alignment may play an important role in annulus fibrosus tissue function. Specifically, these engineered tissues can resist tensile deformation through shearing of the interlamellar matrix as layers of collagen differentially reorient under load. In the present work, a hyperelastic constitutive model was developed to describe the role of interlamellar shearing in reinforcing the tensile response of biologic laminates, and was applied to experimental results from engineered annulus constructs formed from MSC-seeded nanofibrous scaffolds. By applying the constitutive model to uniaxial tensile stress-strain data for bilayers with three different fiber orientations, material parameters were generated that characterize the contributions of extrafibrillar matrix, fibers, and interlamellar shearing interactions. By 10 weeks of in vitro culture, interlamellar shearing accounted for nearly 50% of the total stress associated with uniaxial extension in the anatomic range of ply angle. The model successfully captured changes in function with extracellular matrix deposition through variations in the magnitude of model parameters with culture duration. This work illustrates the value of engineered tissues as tools to further our understanding of structure-function relations in native tissues and as a test-bed for the development of constitutive models to describe them.

Comparison of indoor air pollutants concentration in two Romanian classrooms

NASA Astrophysics Data System (ADS)

Vasile, Vasilica; Dima, Alina; Zorila, Elena; Istrate, Andrei; Catalina, Tiberiu

2018-02-01

This paper investigates the air pollutions in space ventilated in two High School classrooms. The analysis consists of comparison of one classroom with hybrid ventilation system and another one stander-by classroom with natural ventilation. Several studies regarding indoor air quality during the experimental campaign have been done for VOC, CO2, CO, other pollutants, keeping monitored for humidity and temperature. The experimental demonstrated that the highest value for CO2 in stander-by classroom is 2691 ppm and in classroom with hybrid ventilation is 1897 ppm, while values for CO are 1.1 / 1.1 ppm and VOC 0.14 / 0.06 ppm, better use hybrid ventilation.

The ventilation problem in schools: literature review

DOE PAGES

Fisk, W. J.

2017-07-06

Based on a review of literature published in refereed archival journals, ventilation rates in classrooms often fall far short of the minimum ventilation rates specified in standards. We report that there is compelling evidence, from both cross-sectional and intervention studies, of an association of increased student performance with increased ventilation rates. There is evidence that reduced respiratory health effects and reduced student absence are associated with increased ventilation rates. Increasing ventilation rates in schools imposes energy costs and can increase heating, ventilating, and air-conditioning system capital costs. The net annual costs, ranging from a few dollars to about 10 dollarsmore » per person, are less than 0.1% of typical public spending on elementary and secondary education in the United States. Finally, such expenditures seem like a small price to pay given the evidence of health and performance benefits.« less

The ventilation problem in schools: literature review

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

Fisk, W. J.

Based on a review of literature published in refereed archival journals, ventilation rates in classrooms often fall far short of the minimum ventilation rates specified in standards. We report that there is compelling evidence, from both cross-sectional and intervention studies, of an association of increased student performance with increased ventilation rates. There is evidence that reduced respiratory health effects and reduced student absence are associated with increased ventilation rates. Increasing ventilation rates in schools imposes energy costs and can increase heating, ventilating, and air-conditioning system capital costs. The net annual costs, ranging from a few dollars to about 10 dollarsmore » per person, are less than 0.1% of typical public spending on elementary and secondary education in the United States. Finally, such expenditures seem like a small price to pay given the evidence of health and performance benefits.« less

[Experimental study on the influence of natural and artificial ventilation on indoor radon concentration].

PubMed

Remetti, R; Gigante, G E

2010-01-01

The study presents the results of a campaign of measurements on the daily radon concentration using a Genitron Alpha Guard spectrometer. All the measurements have been intended to highlight the radon concentration variability during the 24 hours of the day and trying to find correlations with other ambient parameters such as temperature and pressure or local conditions such as the presence or not of a forced ventilation system. The main part of the measurements have been carried in the area of the Nuclear Measurement Laboratory of the Department of Basic and Applied Sciences for Engineering of "Sapienza" University of Rome. Results show a rapid rise of radon concentration in the night, when the artificial ventilation system was off and with door and windows closed. In the morning, after the opening of door and windows, the concentration falls down abruptly. With artificial ventilation system in function concentration never reaches significant values.

46 CFR 193.15-35 - Enclosure openings.

Code of Federal Regulations, 2010 CFR

2010-10-01

... EQUIPMENT Carbon Dioxide Extinguishing Systems, Details § 193.15-35 Enclosure openings. (a) Where mechanical ventilation is provided for spaces which are protected by carbon dioxide extinguishing systems provisions... to that space. (b) Where natural ventilation is provided for spaces protected by a carbon dioxide...

14 CFR 25.1121 - General.

Code of Federal Regulations, 2013 CFR

2013-01-01

... could be subjected to high temperatures from exhaust system parts, must be fireproof. All exhaust system... ventilated to prevent points of excessively high temperature. (g) Each exhaust shroud must be ventilated or insulated to avoid, during normal operation, a temperature high enough to ignite any flammable fluids or...

14 CFR 25.1121 - General.

Code of Federal Regulations, 2014 CFR

2014-01-01

... could be subjected to high temperatures from exhaust system parts, must be fireproof. All exhaust system... ventilated to prevent points of excessively high temperature. (g) Each exhaust shroud must be ventilated or insulated to avoid, during normal operation, a temperature high enough to ignite any flammable fluids or...

14 CFR 29.1121 - General.

Code of Federal Regulations, 2010 CFR

2010-01-01

... to high temperatures from exhaust system parts, must be fireproof. Each exhaust system component must... ventilated to prevent points of excessively high temperature. (g) Each exhaust shroud must be ventilated or insulated to avoid, during normal operation, a temperature high enough to ignite any flammable fluids or...

14 CFR 25.1121 - General.

Code of Federal Regulations, 2011 CFR

2011-01-01

... could be subjected to high temperatures from exhaust system parts, must be fireproof. All exhaust system... ventilated to prevent points of excessively high temperature. (g) Each exhaust shroud must be ventilated or insulated to avoid, during normal operation, a temperature high enough to ignite any flammable fluids or...

14 CFR 25.1121 - General.

Code of Federal Regulations, 2012 CFR

2012-01-01

... could be subjected to high temperatures from exhaust system parts, must be fireproof. All exhaust system... ventilated to prevent points of excessively high temperature. (g) Each exhaust shroud must be ventilated or insulated to avoid, during normal operation, a temperature high enough to ignite any flammable fluids or...

ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT: NEW CONDENSATOR, INC.--THE CONDENSATOR DIESEL ENGINE RETROFIT CRANKCASE VENTILATION SYSTEM

EPA Science Inventory

EPA's Environmental Technology Verification Program has tested New Condensator Inc.'s Condensator Diesel Engine Retrofit Crankcase Ventilation System. Brake specific fuel consumption (BSFC), the ratio of engine fuel consumption to the engine power output, was evaluated for engine...

46 CFR 193.15-35 - Enclosure openings.

Code of Federal Regulations, 2011 CFR

2011-10-01

... EQUIPMENT Carbon Dioxide Extinguishing Systems, Details § 193.15-35 Enclosure openings. (a) Where mechanical ventilation is provided for spaces which are protected by carbon dioxide extinguishing systems provisions... to that space. (b) Where natural ventilation is provided for spaces protected by a carbon dioxide...

Service bay area, pump room level, showing ventilation fans and ...

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

Service bay area, pump room level, showing ventilation fans and ducts association with evaporative-cooling system. Note battery bank at far right. View to the east - Wellton-Mohawk Irrigation System, Pumping Plant No. 3, South of Interstate 8, Wellton, Yuma County, AZ

Night ventilation control strategies in office buildings

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

Wang, Zhaojun; Yi, Lingli; Gao, Fusheng

2009-10-15

In moderate climates night ventilation is an effective and energy-efficient approach to improve the indoor thermal environment for office buildings during the summer months, especially for heavyweight construction. However, is night ventilation a suitable strategy for office buildings with lightweight construction located in cold climates? In order to answer this question, the whole energy-consumption analysis software EnergyPlus was used to simulate the indoor thermal environment and energy consumption in typical office buildings with night mechanical ventilation in three cities in northern China. The summer outdoor climate data was analyzed, and three typical design days were chosen. The most important factorsmore » influencing night ventilation performance such as ventilation rates, ventilation duration, building mass and climatic conditions were evaluated. When night ventilation operation time is closer to active cooling time, the efficiency of night ventilation is higher. With night ventilation rate of 10 ach, the mean radiant temperature of the indoor surface decreased by up to 3.9 C. The longer the duration of operation, the more efficient the night ventilation strategy becomes. The control strategies for three locations are given in the paper. Based on the optimized strategies, the operation consumption and fees are calculated. The results show that more energy is saved in office buildings cooled by a night ventilation system in northern China than ones that do not employ this strategy. (author)« less

Integration of a photocatalytic multi-tube reactor for indoor air purification in HVAC systems: a feasibility study.

PubMed

van Walsem, Jeroen; Roegiers, Jelle; Modde, Bart; Lenaerts, Silvia; Denys, Siegfried

2018-04-24

This work is focused on an in-depth experimental characterization of multi-tube reactors for indoor air purification integrated in ventilation systems. Glass tubes were selected as an excellent photocatalyst substrate to meet the challenging requirements of the operating conditions in a ventilation system in which high flow rates are typical. Glass tubes show a low-pressure drop which reduces the energy demand of the ventilator, and additionally, they provide a large exposed surface area to allow interaction between indoor air contaminants and the photocatalyst. Furthermore, the performance of a range of P25-loaded sol-gel coatings was investigated, based on their adhesion properties and photocatalytic activities. Moreover, the UV light transmission and photocatalytic reactor performance under various operating conditions were studied. These results provide vital insights for the further development and scaling up of multi-tube reactors in ventilation systems which can provide a better comfort, improved air quality in indoor environments, and reduced human exposure to harmful pollutants.

Chaotic micromixer utilizing electro-osmosis and induced charge electro-osmosis in eccentric annulus

NASA Astrophysics Data System (ADS)

Feng, Huicheng; Wong, Teck Neng; Che, Zhizhao; Marcos

2016-06-01

Efficient mixing is of significant importance in numerous chemical and biomedical applications but difficult to realize rapidly in microgeometries due to the lack of turbulence. We propose to enhance mixing by introducing Lagrangian chaos through electro-osmosis (EO) or induced charge electro-osmosis (ICEO) in an eccentric annulus. The analysis reveals that the created Lagrangian chaos can achieve a homogeneous mixing much more rapidly than either the pure EO or the pure ICEO. Our systematic investigations on the key parameters, ranging from the eccentricity, the alternating time period, the number of flow patterns in one time period, to the specific flow patterns utilized for the Lagrangian chaos creation, present that the Lagrangian chaos is considerably robust. The system can obtain a good mixing effect with wide ranges of eccentricity, alternating time period, and specific flow patterns utilized for the Lagrangian chaos creation as long as the number of flow patterns in one time period is two. As the electric field increases, the time consumption for homogenous mixing is reduced more remarkably for the Lagrangian chaos of the ICEO than that of the EO.

NASA National Combustion Code Simulations

NASA Technical Reports Server (NTRS)

Iannetti, Anthony; Davoudzadeh, Farhad

2001-01-01

A systematic effort is in progress to further validate the National Combustion Code (NCC) that has been developed at NASA Glenn Research Center (GRC) for comprehensive modeling and simulation of aerospace combustion systems. The validation efforts include numerical simulation of the gas-phase combustor experiments conducted at the Center for Turbulence Research (CTR), Stanford University, followed by comparison and evaluation of the computed results with the experimental data. Presently, at GRC, a numerical model of the experimental gaseous combustor is built to simulate the experimental model. The constructed numerical geometry includes the flow development sections for air annulus and fuel pipe, 24 channel air and fuel swirlers, hub, combustor, and tail pipe. Furthermore, a three-dimensional multi-block, multi-grid grid (1.6 million grid points, 3-levels of multi-grid) is generated. Computational simulation of the gaseous combustor flow field operating on methane fuel has started. The computational domain includes the whole flow regime starting from the fuel pipe and the air annulus, through the 12 air and 12 fuel channels, in the combustion region and through the tail pipe.

Glass Bubbles Insulation for Liquid Hydrogen Storage Tanks

NASA Astrophysics Data System (ADS)

Sass, J. P.; Cyr, W. W. St.; Barrett, T. M.; Baumgartner, R. G.; Lott, J. W.; Fesmire, J. E.

2010-04-01

A full-scale field application of glass bubbles insulation has been demonstrated in a 218,000 L liquid hydrogen storage tank. This work is the evolution of extensive materials testing, laboratory scale testing, and system studies leading to the use of glass bubbles insulation as a cost efficient and high performance alternative in cryogenic storage tanks of any size. The tank utilized is part of a rocket propulsion test complex at the NASA Stennis Space Center and is a 1960's vintage spherical double wall tank with an evacuated annulus. The original perlite that was removed from the annulus was in pristine condition and showed no signs of deterioration or compaction. Test results show a significant reduction in liquid hydrogen boiloff when compared to recent baseline data prior to removal of the perlite insulation. The data also validates the previous laboratory scale testing (1000 L) and full-scale numerical modeling (3,200,000 L) of boiloff in spherical cryogenic storage tanks. The performance of the tank will continue to be monitored during operation of the tank over the coming years.

Glass Bubbles Insulation for Liquid Hydrogen Storage Tanks

NASA Technical Reports Server (NTRS)

Sass, J. P.; SaintCyr, W. W.; Barrett, T. M.; Baumgartner, R. G.; Lott, J. W.; Fesmire, J. E.

2009-01-01

A full-scale field application of glass bubbles insulation has been demonstrated in a 218,000 L liquid hydrogen storage tank. This work is the evolution of extensive materials testing, laboratory scale testing, and system studies leading to the use of glass bubbles insulation as a cost efficient and high performance alternative in cryogenic storage tanks of any size. The tank utilized is part of a rocket propulsion test complex at the NASA Stennis Space Center and is a 1960's vintage spherical double wall tank with an evacuated annulus. The original perlite that was removed from the annulus was in pristine condition and showed no signs of deterioration or compaction. Test results show a significant reduction in liquid hydrogen boiloff when compared to recent baseline data prior to removal of the perlite insulation. The data also validates the previous laboratory scale testing (1000 L) and full-scale numerical modeling (3,200,000 L) of boiloff in spherical cryogenic storage tanks. The performance of the tank will continue to be monitored during operation of the tank over the coming years. KEYWORDS: Glass bubble, perlite, insulation, liquid hydrogen, storage tank.

Transport characteristics of expiratory droplets and droplet nuclei in indoor environments with different ventilation airflow patterns.

PubMed

Wan, M P; Chao, C Y H

2007-06-01

Expiratory droplets and droplet nuclei can be pathogen carriers for airborne diseases. Their transport characteristics were studied in detail in two idealized floor-supply-type ventilation flow patterns: Unidirectional-upward and single-side-floor, using a multiphase numerical model. The model was validated by running interferometric Mie imaging experiments using test droplets with nonvolatile content, which formed droplet nuclei, ultimately, in a class-100 clean-room chamber. By comparing the droplet dispersion and removal characteristics with data of two other ceiling-supply ventilation systems collected from a previous work, deviations from the perfectly mixed ventilation condition were found to exist in various cases to different extent. The unidirectional-upward system was found to be more efficient in removing the smallest droplet nuclei (formed from 1.5 mum droplets) by air extraction, but it became less effective for larger droplets and droplet nuclei. Instead, the single-side-floor system was shown to be more favorable in removing these large droplets and droplet nuclei. In the single-side-floor system, the lateral overall dispersion coefficients for the small droplets and nuclei (initial size

Advanced Hybrid Spacesuit Concept Featuring Integrated Open Loop and Closed Loop Ventilation Systems

NASA Technical Reports Server (NTRS)

Daniel, Brian A.; Fitzpatrick, Garret R.; Gohmert, Dustin M.; Ybarra, Rick M.; Dub, Mark O.

2013-01-01

A document discusses the design and prototype of an advanced spacesuit concept that integrates the capability to function seamlessly with multiple ventilation system approaches. Traditionally, spacesuits are designed to operate both dependently and independently of a host vehicle environment control and life support system (ECLSS). Spacesuits that operate independent of vehicle-provided ECLSS services must do so with equipment selfcontained within or on the spacesuit. Suits that are dependent on vehicle-provided consumables must remain physically connected to and integrated with the vehicle to operate properly. This innovation is the design and prototype of a hybrid spacesuit approach that configures the spacesuit to seamlessly interface and integrate with either type of vehicular systems, while still maintaining the ability to function completely independent of the vehicle. An existing Advanced Crew Escape Suit (ACES) was utilized as the platform from which to develop the innovation. The ACES was retrofitted with selected components and one-off items to achieve the objective. The ventilation system concept was developed and prototyped/retrofitted to an existing ACES. Components were selected to provide suit connectors, hoses/umbilicals, internal breathing system ducting/ conduits, etc. The concept utilizes a lowpressure- drop, high-flow ventilation system that serves as a conduit from the vehicle supply into the suit, up through a neck seal, into the breathing helmet cavity, back down through the neck seal, out of the suit, and returned to the vehicle. The concept also utilizes a modified demand-based breathing system configured to function seamlessly with the low-pressure-drop closed-loop ventilation system.

Using Coupled Energy, Airflow and IAQ Software (TRNSYS/CONTAM) to Evaluate Building Ventilation Strategies.

PubMed

Dols, W Stuart; Emmerich, Steven J; Polidoro, Brian J

2016-03-01

Building energy analysis tools are available in many forms that provide the ability to address a broad spectrum of energy-related issues in various combinations. Often these tools operate in isolation from one another, making it difficult to evaluate the interactions between related phenomena and interacting systems, forcing oversimplified assumptions to be made about various phenomena that could otherwise be addressed directly with another tool. One example of such interdependence is the interaction between heat transfer, inter-zone airflow and indoor contaminant transport. In order to better address these interdependencies, the National Institute of Standards and Technology (NIST) has developed an updated version of the multi-zone airflow and contaminant transport modelling tool, CONTAM, along with a set of utilities to enable coupling of the full CONTAM model with the TRNSYS simulation tool in a more seamless manner and with additional capabilities that were previously not available. This paper provides an overview of these new capabilities and applies them to simulating a medium-size office building. These simulations address the interaction between whole-building energy, airflow and contaminant transport in evaluating various ventilation strategies including natural and demand-controlled ventilation. CONTAM has been in practical use for many years allowing building designers, as well as IAQ and ventilation system analysts, to simulate the complex interactions between building physical layout and HVAC system configuration in determining building airflow and contaminant transport. It has been widely used to design and analyse smoke management systems and evaluate building performance in response to chemical, biological and radiological events. While CONTAM has been used to address design and performance of buildings implementing energy conserving ventilation systems, e.g., natural and hybrid, this new coupled simulation capability will enable users to apply the tool to couple CONTAM with existing energy analysis software to address the interaction between indoor air quality considerations and energy conservation measures in building design and analysis. This paper presents two practical case studies using the coupled modelling tool to evaluate IAQ performance of a CO 2 -based demand-controlled ventilation system under different levels of building envelope airtightness and the design and analysis of a natural ventilation system.

Using Coupled Energy, Airflow and IAQ Software (TRNSYS/CONTAM) to Evaluate Building Ventilation Strategies

PubMed Central

Dols, W. Stuart.; Emmerich, Steven J.; Polidoro, Brian J.

2016-01-01

Building energy analysis tools are available in many forms that provide the ability to address a broad spectrum of energy-related issues in various combinations. Often these tools operate in isolation from one another, making it difficult to evaluate the interactions between related phenomena and interacting systems, forcing oversimplified assumptions to be made about various phenomena that could otherwise be addressed directly with another tool. One example of such interdependence is the interaction between heat transfer, inter-zone airflow and indoor contaminant transport. In order to better address these interdependencies, the National Institute of Standards and Technology (NIST) has developed an updated version of the multi-zone airflow and contaminant transport modelling tool, CONTAM, along with a set of utilities to enable coupling of the full CONTAM model with the TRNSYS simulation tool in a more seamless manner and with additional capabilities that were previously not available. This paper provides an overview of these new capabilities and applies them to simulating a medium-size office building. These simulations address the interaction between whole-building energy, airflow and contaminant transport in evaluating various ventilation strategies including natural and demand-controlled ventilation. Practical Application CONTAM has been in practical use for many years allowing building designers, as well as IAQ and ventilation system analysts, to simulate the complex interactions between building physical layout and HVAC system configuration in determining building airflow and contaminant transport. It has been widely used to design and analyse smoke management systems and evaluate building performance in response to chemical, biological and radiological events. While CONTAM has been used to address design and performance of buildings implementing energy conserving ventilation systems, e.g., natural and hybrid, this new coupled simulation capability will enable users to apply the tool to couple CONTAM with existing energy analysis software to address the interaction between indoor air quality considerations and energy conservation measures in building design and analysis. This paper presents two practical case studies using the coupled modelling tool to evaluate IAQ performance of a CO2-based demand-controlled ventilation system under different levels of building envelope airtightness and the design and analysis of a natural ventilation system. PMID:27099405

Biomechanical influence of disk properties on the load transfer of healthy and degenerated disks using a poroelastic finite element model.

PubMed

Chagnon, Amélie; Aubin, Carl-Eric; Villemure, Isabelle

2010-11-01

Spine degeneration is a pathology that will affect 80% of the population. Since the intervertebral disks play an important role in transmitting loads through the spine, the aim of this study was to evaluate the biomechanical impact of disk properties on the load carried by healthy (Thompson grade I) and degenerated (Thompson grades III and IV) disks. A three-dimensional parametric poroelastic finite element model of the L4/L5 motion segment was developed. Grade I, grade II, and grade IV disks were modeled by altering the biomechanical properties of both the annulus and nucleus. Models were validated using published creep experiments, in which a constant compressive axial stress of 0.35 MPa was applied for 4 h. Pore pressure (PP) and effective stress (S(E)) were analyzed as a function of time following loading application (1 min, 5 min, 45 min, 125 min, and 245 min) and discal region along the midsagittal profile for each disk grade. A design of experiments was further implemented to analyze the influence of six disk parameters (disk height (H), fiber proportion (%F), drained Young's modulus (E(a),E(n)), and initial permeability (k(a),k(n)) of both the annulus and nucleus) on load-sharing for disk grades I and IV. Simulations of grade I, grade III, and grade IV disks agreed well with the available published experimental data. Disk height (H) had a significant influence (p<0.05) on the PP and S(E) during the entire loading history for both healthy and degenerated disk models. Young's modulus of the annulus (E(a)) significantly affected not only S(E) in the annular region for both disk grades in the initial creep response but also S(E) in the nucleus zone for degenerated disks with further creep response. The nucleus and annulus permeabilities had a significant influence on the PP distribution for both disk grades, but this effect occurred at earlier stages of loading for degenerated than for healthy disk models. This is the first study that investigates the biomechanical influence of both geometrical and material disk properties on the load transfer of healthy and degenerated disks. Disk height is a significant parameter for both healthy and degenerated disks during the entire loading. Changes in the annulus stiffness, as well as in the annulus and nucleus permeability, control load-sharing in different ways for healthy and degenerated disks.

Computer-aided evaluation of low-dose and low-contrast agent third-generation dual-source CT angiography prior to transcatheter aortic valve implantation (TAVI).

PubMed

Dankerl, Peter; Hammon, Matthias; Seuss, Hannes; Tröbs, Monique; Schuhbaeck, Annika; Hell, Michaela M; Cavallaro, Alexander; Achenbach, Stephan; Uder, Michael; Marwan, Mohamed

2017-05-01

To evaluate the performance of computer-aided evaluation software for a comprehensive workup of patients prior to transcatheter aortic valve implantation (TAVI) using low-contrast agent and low radiation dose third-generation dual-source CT angiography. We evaluated 30 consecutive patients scheduled for TAVI. All patients underwent ECG-triggered high-pitch dual-source CT angiography of the aortic root and aorta with a standardized contrast agent volume (30 ml Imeron350, flow rate 4 ml/s) and low-dose (100 kv/350 mAs) protocol. An expert (10 years of experience) manually evaluated aortic root and iliac access dimensions (distance between coronary ostia and aortic annulus, minimal/maximal diameters and area-derived diameter of the aortic annulus) and best CT-predicted fluoroscopic projection angle as the reference standard. Utilizing computer-aided software (syngo.via), the same pre-TAVI workup was performed and compared to the reference standard. Mean CTDI[Formula: see text] was 3.46 mGy and mean DLP 217.6 ± 12.1 mGy cm, corresponding to a mean effective dose of 3.7 ± 0.2 mSv. Computer-aided evaluation was successful in all but one patient. Compared to the reference standard, Bland-Altman analysis indicated very good agreement for the distances between aortic annulus and coronary ostia (RCA: mean difference 0.8 mm; 95 % CI 0.4-1.2 mm; LM: mean difference 0.9 mm; 95 % CI 0.5-1.3 mm); however, we demonstrated a systematic overestimation of annulus- derived diameter using the software (mean difference 44.4 mm[Formula: see text]; 95 % CI 30.4-58.3 mm[Formula: see text]). Based on respective annulus dimensions, the recommended prosthesis size (Edwards SAPIEN 3) matched in 26 out of the 29 patients (90 %). CT-derived fluoroscopic projection angles showed an excellent agreement for both methods. Out of 58 iliac arteries, 15 (25 %) arteries could not be segmented by the software. Preprocessing time of the software was 71 ± 11 s (range 51-96 s), and reading time with the software was 118 ± 31 s (range 68-201 s). In the workup of pre-TAVI CT angiography, computer-aided evaluation of low-contrast, low-dose examinations is feasible with good agreement and quick reading time. However, a systematic overestimation of the aortic annulus area is observed.

The effect of acute mechanical left ventricular unloading on ovine tricuspid annular size and geometry.

PubMed

Malinowski, Marcin; Wilton, Penny; Khaghani, Asghar; Brown, Michael; Langholz, David; Hooker, Victoria; Eberhart, Lenora; Hooker, Robert L; Timek, Tomasz A

2016-09-01

Left ventricular assist device (LVAD) implantation may alter right ventricular shape and function and lead to tricuspid regurgitation. This in turn has been reported to be a determinant of right ventricular (RV) failure after LVAD implantation, but the effect of mechanical left ventricular (LV) unloading on the tricuspid annulus is unknown. The aim of the study was to provide insight into the effect of LVAD support on tricuspid annular geometry and dynamics that may help to optimize LV unloading with the least deleterious effect on the right-sided geometry. In seven open-chest anaesthetized sheep, nine sonomicrometry crystals were implanted on the right ventricle. Additional nine crystals were implanted around the tricuspid annulus, with one crystal at each commissure defining three separate annular regions: anterior, posterior and septal. Left ventricular unloading was achieved by connecting a cannula in the left atrium and the aorta to a continuous-flow pump. The pump was used for 15 min at a full flow of 3.8 ± 0.3 l/min. Epicardial echocardiography was used to assess the degree of tricuspid insufficiency. Haemodynamic, echocardiographic and sonomicrometry data were collected before and during full unloading. Tricuspid annular area, and the regional and total perimeter were calculated from crystal coordinates, while 3D annular geometry was expressed as the orthogonal distance of each annular crystal to the least squares plane of all annular crystals. There was no significant tricuspid regurgitation observed either before or during LV unloading. Right ventricular free wall to septum diameter increased significantly at end-diastole during unloading from 23.6 ± 5.8 to 26.3 ± 6.5 mm (P = 0.009), but the right ventricular volume, tricuspid annular area and total perimeter did not change from baseline. However, the septal part of the annulus significantly decreased its maximal length (38.6 ± 8.1 to 37.9 ± 8.2 mm, P = 0.03). Annular contraction was not altered. The tricuspid annulus had a complex 3D saddle-shaped geometry that was unaffected during experimental conditions. In healthy sheep hearts, left ventricular unloading increased septal-free wall RV diameter and reduced the length of the septal annulus, without altering the motion or geometry of the tricuspid annulus. Acute left ventricular unloading alone in healthy sheep was not sufficient to significantly perturb tricuspid annular dynamics and result in tricuspid insufficiency. © The Author 2016. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

The Geometric Nature of the Flaschka Transformation

NASA Astrophysics Data System (ADS)

Bloch, Anthony M.; Gay-Balmaz, François; Ratiu, Tudor S.

2017-06-01

We show that the Flaschka map, originally introduced to analyze the dynamics of the integrable Toda lattice system, is the inverse of a momentum map. We discuss the geometrical setting of the map and apply it to the generalized Toda lattice systems on semisimple Lie algebras, the rigid body system on Toda orbits, and to coadjoint orbits of semidirect products groups. In addition, we develop an infinite-dimensional generalization for the group of area preserving diffeomorphisms of the annulus and apply it to the analysis of the dispersionless Toda lattice PDE and the solvable rigid body PDE.

The Influence of Internal Wall and Floor Covering Materials and Ventilation Type on Indoor Radon and Thoron Levels in Hospitals of Kermanshah, Iran.

PubMed

Pirsaheb, Meghdad; Najafi, Farid; Haghparast, Abbas; Hemati, Lida; Sharafi, Kiomars; Kurd, Nematullah

2016-10-01

Building materials and the ventilation rate of a building are two main factors influencing indoor radon and thoron levels (two radioactive gases which have the most important role in human natural radiation exposure within dwellings). This analytical descriptive study was intended to determine the relationship between indoor radon and thoron concentrations and the building materials used in interior surfaces, as well as between those concentrations and the type of ventilation system (natural or artificial). 102 measurements of radon and thoron levels were taken from different parts of three hospital buildings in the city of Kermanshah in the west of Iran, using an RTM-1688-2 radon meter. Information on the type of building material and ventilation system in the measurement location was collected and then analyzed using Stata 8 software and multivariate linear regression. In terms of radon and thoron emissions, travertine and plaster were found to be the most appropriate and inappropriate covering for walls, respectively. Furthermore, granite and travertine were discovered to be inappropriate materials for flooring, while plastic floor covering was found suitable. Natural ventilation performed better for radon, while artificial ventilation worked better for thoron. Internal building materials and ventilation type affect indoor radon and thoron concentrations. Therefore, the use of proper materials and adequate ventilation can reduce the potential human exposure to radon and thoron. This is of utmost importance, particularly in buildings with a high density of residents, including hospitals.

Influence of Applying Additional Forcing Fans for the Air Distribution in Ventilation Network

NASA Astrophysics Data System (ADS)

Szlązak, Nikodem; Obracaj, Dariusz; Korzec, Marek

2016-09-01

Mining progress in underground mines cause the ongoing movement of working areas. Consequently, it becomes necessary to adapt the ventilation network of a mine to direct airflow into newly-opened districts. For economic reasons, opening new fields is often achieved via underground workings. Length of primary intake and return routes increases and also increases the total resistance of a complex ventilation network. The development of a subsurface structure can make it necessary to change the air distribution in a ventilation network. Increasing airflow into newly-opened districts is necessary. In mines where extraction does not entail gas-related hazards, there is possibility of implementing a push-pull ventilation system in order to supplement airflows to newly developed mining fields. This is achieved by installing subsurface fan stations with forcing fans at the bottom of downcast shaft. In push-pull systems with multiple main fans, it is vital to select forcing fans with characteristic curves matching those of the existing exhaust fans to prevent undesirable mutual interaction. In complex ventilation networks it is necessary to calculate distribution of airflow (especially in networks with a large number of installed fans). In the article the influence of applying additional forcing fans for the air distribution in ventilation network for underground mine were considered. There are also analysed the extent of overpressure caused by the additional forcing fan in branches of the ventilation network (the operating range of additional forcing fan). Possibilities of increasing airflow rate in working areas were conducted.

46 CFR 154.1200 - Mechanical ventilation system: General.

Code of Federal Regulations, 2011 CFR

2011-10-01

... gas-safe space in the cargo area. (4) Each space that contains inert gas generators, except main...) Each cargo compressor room, pump room, gas-dangerous cargo control station, and space that contains... following must have a supply-type mechanical ventilation system: (1) Each space that contains electric...

Parametric instabilities of rotor-support systems with application to industrial ventilators

NASA Technical Reports Server (NTRS)

Parszewski, Z.; Krodkiemski, T.; Marynowski, K.

1980-01-01

Rotor support systems interaction with parametric excitation is considered for both unequal principal shaft stiffness (generators) and offset disc rotors (ventilators). Instability regions and types of instability are computed in the first case, and parametric resonances in the second case. Computed and experimental results are compared for laboratory machine models. A field case study of parametric vibrations in industrial ventilators is reported. Computed parametric resonances are confirmed in field measurements, and some industrial failures are explained. Also the dynamic influence and gyroscopic effect of supporting structures are shown and computed.

Natural ventilation systems to enhance sustainability in buildings: a review towards zero energy buildings in schools

NASA Astrophysics Data System (ADS)

Gil-Baez, Maite; Barrios-Padura, Ángela; Molina-Huelva, Marta; Chacartegui, Ricardo

2017-11-01

European regulations set the condition of Zero Energy Buildings for new buildings since 2020, with an intermediate milestone in 2018 for public buildings, in order to control greenhouse gases emissions control and climate change mitigation. Given that main fraction of energy consumption in buildings operation is due to HVAC systems, advances in its design and operation conditions are required. One key element for energy demand control is passive design of buildings. On this purpose, different recent studies and publications analyse natural ventilation systems potential to provide indoor air quality and comfort conditions minimizing electric power consumption. In these passive systems are of special relevance their capacities as passive cooling systems as well as air renovation systems, especially in high-density occupied spaces. With adequate designs, in warm/mild climates natural ventilation systems can be used along the whole year, maintaining indoor air quality and comfort conditions with small support of other heating/cooling systems. In this paper is analysed the state of the art of natural ventilation systems applied to high density occupied spaces with special focus on school buildings. The paper shows the potential and applicability of these systems for energy savings and discusses main criteria for their adequate integration in school building designs.

Code System to Calculate Tornado-Induced Flow Material Transport.

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

ANDRAE, R. W.

1999-11-18

Version: 00 TORAC models tornado-induced flows, pressures, and material transport within structures. Its use is directed toward nuclear fuel cycle facilities and their primary release pathway, the ventilation system. However, it is applicable to other structures and can model other airflow pathways within a facility. In a nuclear facility, this network system could include process cells, canyons, laboratory offices, corridors, and offgas systems. TORAC predicts flow through a network system that also includes ventilation system components such as filters, dampers, ducts, and blowers. These ventilation system components are connected to the rooms and corridors of the facility to form amore » complete network for moving air through the structure and, perhaps, maintaining pressure levels in certain areas. The material transport capability in TORAC is very basic and includes convection, depletion, entrainment, and filtration of material.« less

A dual closed-loop control system for mechanical ventilation.

PubMed

Tehrani, Fleur; Rogers, Mark; Lo, Takkin; Malinowski, Thomas; Afuwape, Samuel; Lum, Michael; Grundl, Brett; Terry, Michael

2004-04-01

Closed-loop mechanical ventilation has the potential to provide more effective ventilatory support to patients with less complexity than conventional ventilation. The purpose of this study was to investigate the effectiveness of an automatic technique for mechanical ventilation. Two closed-loop control systems for mechanical ventilation are combined in this study. In one of the control systems several physiological data are used to automatically adjust the frequency and tidal volume of breaths of a patient. This method, which is patented under US Patent number 4986268, uses the criterion of minimal respiratory work rate to provide the patient with a natural pattern of breathing. The inputs to the system include data representing CO2 and O2 levels of the patient as well as respiratory compliance and airway resistance. The I:E ratio is adjusted on the basis of the respiratory time constant to allow for effective emptying of the lungs in expiration and to avoid intrinsic positive end expiratory pressure (PEEP). This system is combined with another closed-loop control system for automatic adjustment of the inspired fraction of oxygen of the patient. This controller uses the feedback of arterial oxygen saturation of the patient and combines a rapid stepwise control procedure with a proportional-integral-derivative (PID) control algorithm to automatically adjust the oxygen concentration in the patient's inspired gas. The dual closed-loop control system has been examined by using mechanical lung studies, computer simulations and animal experiments. In the mechanical lung studies, the ventilation controller adjusted the breathing frequency and tidal volume in a clinically appropriate manner in response to changes in respiratory mechanics. The results of computer simulations and animal studies under induced disturbances showed that blood gases were returned to the normal physiologic range in less than 25 s by the control system. In the animal experiments understeady-state conditions, the maximum standard deviations of arterial oxygen saturation and the end-tidal partial pressure of CO2 were +/- 1.76% and +/- 1.78 mmHg, respectively. The controller maintained the arterial blood gases within normal limits under steady-state conditions and the transient response of the system was robust under various disturbances. The results of the study have showed that the proposed dual closed-loop technique has effectively controlled mechanical ventilation under different test conditions.

[Hygienic Inspections of Ventilation Systems Under Resting Conditions (According to DIN 1946-4:1999-03) - A Retrospective Assessment].

PubMed

Friedrich, Lena; Boeckelmann, Irina

2018-01-11

Hygienic and microbiologically sterile air quality is essential for successful guideline-based work in operating theatres. To ensure clean air and to reduce contamination during surgery, ventilation systems are indispensable. Ventilation systems should be especially designed to keep the number of particles and germs under statutory limits. Therefore, they must be operated to recognised standards of good practice and be periodically inspected and maintained. The objective of this study was to prove, through the analysis of observation outside surgery time (rest condition), the effects of ventilation systems on air quality in a medical facility. Measurements were taken in 34 operating theatres annually over a period of ten years outside surgery time (resting condition) but with the air ventilation system operating under full load. 29 operating theatres were provided with laminar air flow and five theatres with turbulent air flow systems. In each operating theatre, air cleanliness was analysed by measuring the amount of airborne particles and airborne germs. Measuring points were determined 10 mm beneath the supply-air ceiling in the centre of the operating theatre and at one position outside the supply-air ceiling. The number of airborne particles at the supply-air ceiling was between 0/m³ and 4,441/m³ of air and, as such, the limiting factor was never exceeded. However, airborne germ measurements of between 0 CFU/m³ and 200 CFU/m³ (CFU: colony forming units) demonstrated that the limiting factor for this criterion was exceeded in 10.9% of occasions. In general, the values in the middle of the room were higher than at the supply-air ceiling. There were significant differences (p < 0.001) between the values at the supply-air ceiling, the surgery table and the values outside the supply-air ceiling. The results show the positive impact of ventilation systems on the air cleanliness in operating theatres. However, laminar airflow systems seem to create cleaner air than conventional ventilation systems. The size of the supply-air ceiling plays an important role in the prevention of the contamination of the staff, the surgical field, the instrument table and the patient. However, the effect on surgical site infections has not been verified. Improved measuring methods should be considered. Georg Thieme Verlag KG Stuttgart · New York.

Thermionic converter temperature controller

DOEpatents

Shaner, Benjamin J [McMurray, PA; Wolf, Joseph H [Pittsburgh, PA; Johnson, Robert G. R. [Trafford, PA

2001-04-24

A method and apparatus for controlling the temperature of a thermionic reactor over a wide range of operating power, including a thermionic reactor having a plurality of integral cesium reservoirs, a honeycomb material disposed about the reactor which has a plurality of separated cavities, a solid sheath disposed about the honeycomb material and having an opening therein communicating with the honeycomb material and cavities thereof, and a shell disposed about the sheath for creating a coolant annulus therewith so that the coolant in the annulus may fill the cavities and permit nucleate boiling during the operation of the reactor.

Efficacy of identifying stocked crappies in a Tennessee reservoir through oxytetracycline marking

USGS Publications Warehouse

Isermann, D.A.; Bettoli, P.W.; Sammons, S.M.

1999-01-01

Oxytetracycline (OTC) immersion was used to identify black-nosed crappies, a morphological variation of black crappie Pomoxis nigromaculatus, stocked into Normandy Reservoir, Tennessee, during fall 1997. The technique effectively marked 97% of the treated fish. Analysis of one otolith per fish by one reader successfully identified 98% of marked and unmarked fish in a blind test. Marks were formed before annulus formation and were not obscured by annulus-related autofluorescence, suggesting that OTC can be effectively used late in the year (October and November) in Tennessee.

Technical Note: A proposal of air ventilation system design criteria for a clinical room in a heavy-ion medical facility.

PubMed

Kum, Oyeon

2018-06-01

An optimized air ventilation system design for a treatment room in Heavy-ion Medical Facility is an important issue in the aspects of nuclear safety because the activated air produced in a treatment room can directly affect the medical staff and the general public in the radiation-free area. Optimized design criteria of air ventilation system for a clinical room in 430 MeV/u carbon ion beam medical accelerator facility was performed by using a combination of MCNPX2.7.0 and CINDER'90 codes. Effective dose rate and its accumulated effective dose by inhalation and residual gamma were calculated for a normal treatment scenario (2 min irradiation for one fraction) as a function of decay time. Natural doses around the site were measured before construction and used as reference data. With no air ventilation system, the maximum effective dose rate was about 3 μSv/h (total dose of 90 mSv/y) and minimum 0.2 μSv/h (total dose of 6 mSv/y), which are over the legal limits for medical staff and for the general public. Although inhalation dose contribution was relatively small, it was considered seriously because of its long-lasting effects in the body. The integrated dose per year was 1.8 mSv/y in the radiation-free area with the 20-min rate of air ventilation system. An optimal air ventilation rate of 20 min is proposed for a clinical room, which also agrees with the best mechanical design value. © 2018 American Association of Physicists in Medicine.

Wii, Kinect, and Move. Heart Rate, Oxygen Consumption, Energy Expenditure, and Ventilation due to Different Physically Active Video Game Systems in College Students.

PubMed

Scheer, Krista S; Siebrant, Sarah M; Brown, Gregory A; Shaw, Brandon S; Shaw, Ina

Nintendo Wii, Sony Playstation Move , and Microsoft XBOX Kinect are home video gaming systems that involve player movement to control on-screen game play. Numerous investigations have demonstrated that playing Wii is moderate physical activity at best, but Move and Kinect have not been as thoroughly investigated. The purpose of this study was to compare heart rate, oxygen consumption, and ventilation while playing the games Wii Boxing, Kinect Boxing, and Move Gladiatorial Combat. Heart rate, oxygen consumption, and ventilation were measured at rest and during a graded exercise test in 10 males and 9 females (19.8 ± 0.33 y, 175.4 ± 2.0 cm, 80.2 ± 7.7 kg,). On another day, in a randomized order, the participants played Wii Boxing, K inect Boxing, and Move Gladiatorial Combat while heart rate, ventilation, and oxygen consumption were measured. There were no differences in heart rate (116.0 ± 18.3 vs. 119.3 ± 17.6 vs. 120.1 ± 17.6 beats/min), oxygen consumption (9.2 ± 3.0 vs. 10.6 ± 2.4 vs. 9.6 ± 2.4 ml/kg/min), or minute ventilation (18.9 ± 5.7 vs. 20.8 ± 8.0 vs. 19.7 ± 6.4 L/min) when playing Wii boxing, Kinect boxing, or Move Gladiatorial Combat (respectively). Playing Nintendo Wii Boxing, XBOX Kinect Boxing, and Sony PlayStation Move Gladiatorial Combat all increase heart rate, oxygen consumption, and ventilation above resting levels but there were no significant differences between gaming systems. Overall, playing a "physically active" home video game system does not meet the minimal threshold for moderate intensity physical activity, regardless of gaming system.

Wii, Kinect, and Move. Heart Rate, Oxygen Consumption, Energy Expenditure, and Ventilation due to Different Physically Active Video Game Systems in College Students

PubMed Central

SCHEER, KRISTA S.; SIEBRANT, SARAH M.; BROWN, GREGORY A.; SHAW, BRANDON S.; SHAW, INA

2014-01-01

Nintendo Wii, Sony Playstation Move, and Microsoft XBOX Kinect are home video gaming systems that involve player movement to control on-screen game play. Numerous investigations have demonstrated that playing Wii is moderate physical activity at best, but Move and Kinect have not been as thoroughly investigated. The purpose of this study was to compare heart rate, oxygen consumption, and ventilation while playing the games Wii Boxing, Kinect Boxing, and Move Gladiatorial Combat. Heart rate, oxygen consumption, and ventilation were measured at rest and during a graded exercise test in 10 males and 9 females (19.8 ± 0.33 y, 175.4 ± 2.0 cm, 80.2 ± 7.7 kg,). On another day, in a randomized order, the participants played Wii Boxing, Kinect Boxing, and Move Gladiatorial Combat while heart rate, ventilation, and oxygen consumption were measured. There were no differences in heart rate (116.0 ± 18.3 vs. 119.3 ± 17.6 vs. 120.1 ± 17.6 beats/min), oxygen consumption (9.2 ± 3.0 vs. 10.6 ± 2.4 vs. 9.6 ± 2.4 ml/kg/min), or minute ventilation (18.9 ± 5.7 vs. 20.8 ± 8.0 vs. 19.7 ± 6.4 L/min) when playing Wii boxing, Kinect boxing, or Move Gladiatorial Combat (respectively). Playing Nintendo Wii Boxing, XBOX Kinect Boxing, and Sony PlayStation Move Gladiatorial Combat all increase heart rate, oxygen consumption, and ventilation above resting levels but there were no significant differences between gaming systems. Overall, playing a “physically active” home video game system does not meet the minimal threshold for moderate intensity physical activity, regardless of gaming system. PMID:27182399

[Assessment of the air quality improment of cleaning and disinfection on central air-conditioning ventilation system].

PubMed

Liu, Hongliang; Zhang, Lei; Feng, Lihong; Wang, Fei; Xue, Zhiming

2009-09-01

To assess the effect of air quality of cleaning and disinfection on central air-conditioning ventilation systems. 102 air-conditioning ventilation systems in 46 public facilities were sampled and investigated based on Hygienic assessment criterion of cleaning and disinfection of public central air-conditioning systems. Median dust volume decreased from 41.8 g/m2 to 0.4 g/m2, and the percentage of pipes meeting the national standard for dust decreased from 17.3% (13/60) to 100% (62/62). In the dust, median aerobic bacterial count decreased from 14 cfu/cm2 to 1 cfu/cm2. Median aerobic fungus count decreased from 10 cfu/cm2 to 0 cfu/cm2. The percentage of pipes with bacterial and fungus counts meeting the national standard increased from 92.4% (171/185) and 82.2% (152/185) to 99.4% (165/166) and 100% (166/166), respectively. In the ventilation air, median aerobic bacterial count decreased from 756 cfu/m3 to 229 cfu/m3. Median aerobic fungus count decreased from 382 cfu/m3 to 120 cfu/m3. The percentage of pipes meeting the national standard for ventilation air increased from 33.3% (81/243) and 62.1% (151/243) to 79.8% (292/366) and 87.7% (242/276), respectively. But PM10 rose from 0.060 mg/m3 to 0.068 mg/m3, and the percentage of pipes meeting the national standard for PM10 increased from 74.2% (13/60) to 90.2% (46/51). The cleaning and disinfection of central air-conditioning ventilation systems could have a beneficial effect of air quality.

The effect of helium on ventilator performance: study of five ventilators and a bedside Pitot tube spirometer.

PubMed

Oppenheim-Eden, A; Cohen, Y; Weissman, C; Pizov, R

2001-08-01

To assess in vitro the performance of five mechanical ventilators-Siemens 300 and 900C (Siemens-Elma; Solna, Sweden), Puritan Bennett 7200 (Nellcor Puritan Bennett; Pleasanton, CA), Evita 4 (Dragerwerk; Lubeck, Germany), and Bear 1000 (Bear Medical Systems; Riverside CA)-and a bedside sidestream spirometer (Datex CS3 Respiratory Module; Datex-Ohmeda; Helsinki, Finland) during ventilation with helium-oxygen mixtures. In vitro study. ICUs of two university-affiliated hospitals. Each ventilator was connected to 100% helium through compressed air inlets and then tested at three to six different tidal volume (VT) settings using various helium-oxygen concentrations (fraction of inspired oxygen [FIO(2)] of 0.2 to 1.0). FIO(2) and VT were measured with the Datex CS3 spirometer, and VT was validated with a water-displacement spirometer. The Puritan Bennett 7200 ventilator did not function with helium. With the other four ventilators, delivered FIO(2) was lower than the set FIO(2). For the Siemens 300 and 900C ventilators, this difference could be explained by the lack of 21% oxygen when helium was connected to the air supply port, while for the other two ventilators, a nonlinear relation was found. The VT of the Siemens 300 ventilator was independent of helium concentration, while for the other three ventilators, delivered VT was greater than the set VT and was dependent on helium concentration. During ventilation with 80% helium and 20% oxygen, VT increased to 125% of set VT for the Siemens 900C ventilator, and more than doubled for the Evita 4 and Bear 1000 ventilators. Under the same conditions, the Datex CS3 spirometer underestimated the delivered VT by about 33%. At present, no mechanical ventilator is calibrated for use with helium. This investigation offers correction factors for four ventilators for ventilation with helium.

30 CFR 57.11059 - Respirable atmosphere for hoist operators underground.

Code of Federal Regulations, 2010 CFR

2010-07-01

... independent ventilation system shall convert, without contamination, to an approved and properly maintained 2... evacuation. Air for the enclosure's ventilation system shall be provided in one of the following ways: (1) Air coursed from the surface through a borehole into the hoist enclosure directly or through a metal...

A Qualitative Analogy for Respiratory Mechanics

ERIC Educational Resources Information Center

Baptista, Vander

2010-01-01

The geometric configuration and mechanical properties of the integral elements of the respiratory system, as well as the modus operandi of the interacting parts in the ventilation process, comprise a hard-to-visualize system, making the mechanics of pulmonary ventilation a confusing topic for students and a difficult task for the teacher. To…

Breathing Easy

EPA Pesticide Factsheets

This fact sheet provides practical information and guidance to auto refinish shops on proper ventilation of paint mixing rooms, including ventilation system basics and diagrams, risk reduction ideas, common mistakes, tips, and design considerations.

Comparison of freezing control strategies for residential air-to-air heat recovery ventilators

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

Phillips, E.G.; Bradley, L.C.; Chant, R.E.

1989-01-01

A comparison of the energy performance of defrost and frost control strategies for residential air-to-air heat recovery ventilators (HRV) has been carried out by using computer simulations for various climatic conditions. This paper discusses the results and conclusions from the comparisons and their implications for the heat recovery ventilator manufacturers and system designers.

End-expiratory lung volume and ventilation distribution with different continuous positive airway pressure systems in volunteers.

PubMed

Andersson, B; Lundin, S; Lindgren, S; Stenqvist, O; Odenstedt Hergès, H

2011-02-01

Continuous positive airway pressure (CPAP) has been shown to improve oxygenation and a number of different CPAP systems are available. The aim of this study was to assess lung volume and ventilation distribution using three different CPAP techniques. A high-flow CPAP system (HF-CPAP), an ejector-driven system (E-CPAP) and CPAP using a Servo 300 ventilator (V-CPAP) were randomly applied at 0, 5 and 10 cmH₂O in 14 volunteers. End-expiratory lung volume (EELV) was measured by N₂ dilution at baseline; changes in EELV and tidal volume distribution were assessed by electric impedance tomography. Higher end-expiratory and mean airway pressures were found using the E-CPAP vs. the HF-CPAP and the V-CPAP system (P<0.01). EELV increased markedly from baseline, 0 cmH₂O, with increased CPAP levels: 1110±380, 1620±520 and 1130±350 ml for HF-, E- and V-CPAP, respectively, at 10 cmH₂O. A larger fraction of the increase in EELV occurred for all systems in ventral compared with dorsal regions (P<0.01). In contrast, tidal ventilation was increasingly directed toward dorsal regions with increasing CPAP levels (P<0.01). The increase in EELV as well as the tidal volume redistribution were more pronounced with the E-CPAP system as compared with both the HF-CPAP and the V-CPAP systems (P<0.05) at 10 cmH₂O. EELV increased more in ventral regions with increasing CPAP levels, independent of systems, leading to a redistribution of tidal ventilation toward dorsal regions. Different CPAP systems resulted in different airway pressure profiles, which may result in different lung volume expansion and tidal volume distribution. © 2010 The Authors. Journal compilation © 2010 The Acta Anaesthesiologica Scandinavica Foundation.

Air quality and ventilation fan control based on aerosol measurement in the bi-directional undersea Bømlafjord tunnel.

PubMed

Indrehus, Oddny; Aralt, Tor Tybring

2005-04-01

Aerosol, NO and CO concentration, temperature, air humidity, air flow and number of running ventilation fans were measured by continuous analysers every minute for a whole week for six different one-week periods spread over ten months in 2001 and 2002 at measuring stations in the 7860 m long tunnel. The ventilation control system was mainly based on aerosol measurements taken by optical scatter sensors. The ventilation turned out to be satisfactory according to Norwegian air quality standards for road tunnels; however, there was some uncertainty concerning the NO2 levels. The air humidity and temperature inside the tunnel were highly influenced by the outside metrological conditions. Statistical models for NO concentration were developed and tested; correlations between predicted and measured NO were 0.81 for a partial least squares regression (PLS1) model based on CO and aerosol, and 0.77 for a linear regression model based only on aerosol. Hence, the ventilation control system should not solely be based on aerosol measurements. Since NO2 is the hazardous polluter, modelling NO2 concentration rather than NO should be preferred in any further optimising of the ventilation control.