Dynamic upper respiratory abnormalities in Thoroughbred racehorses in South Africa

Directory of Open Access Journals (Sweden)

Javier E. Mirazo

2014-11-01

Full Text Available Upper airway endoscopy at rest has been the diagnostic method of choice for equine upper respiratory tract (URT conditions. Development of high-speed treadmill endoscopy improved the sensitivity of URT endoscopy by allowing observation of the horse’s nasopharynx and larynx during exercise. However, treadmill exercise may not always accurately represent the horse’s normal exercise as track surface, rider, tack and environmental variables are altered. Recently, the development of dynamic overground endoscopy (DOE has addressed some of these shortcomings. A retrospective study was undertaken to describe the URT abnormalities detected during DOE in racehorses presenting with poor performance and/or abnormal respiratory noise. Patient records of Thoroughbred racehorses undergoing DOE from November 2011 to August 2012 were reviewed. Data collected included signalment, primary complaint, distance exercised, maximum speed and dynamic airway abnormalities detected. Fifty-two horses underwent DOE for investigation of poor performance and/or abnormal respiratory noise. The main abnormalities detected included axial deviation of the aryepiglottic folds (40%, vocal cord collapse (35%, abnormal arytenoid function (33% and dorsal displacement of the soft palate (25%. A total of 40 horses were diagnosed with one or more abnormalities of the URT (77%. Fifteen horses (29% had a single abnormality and 25 horses (48% had multiple abnormalities. This study showed that DOE is a useful technique for investigating dynamic disorders of the URT in racehorses in South Africa. The total number and type of dynamic pathological conditions were comparable with those identified in similar populations in other geographical locations.

[Effect of physical properties of respiratory gas on pneumotachographic measurement of ventilation in newborn infants].

Science.gov (United States)

Foitzik, B; Schmalisch, G; Wauer, R R

1994-04-01

The measurement of ventilation in neonates has a number of specific characteristics; in contrast to lung function testing in adults, the inspiratory gas for neonates is often conditioned. In pneumotachographs (PNT) based on Hagen-Poiseuille's law, changes in physical characteristics of respiratory gas (temperature, humidity, pressure and oxygen fraction [FiO2]) produce a volume change as calculated with the ideal gas equation p*V/T = const; in addition, the viscosity of the gas is also changed, thus leading to measuring errors. In clinical practice, the effect of viscosity on volume measurement is often ignored. The accuracy of these empirical laws was investigated in a size 0 Fleisch-PNT using a flow-through technique and variously processed respiratory gas. Spontaneous breathing was simulated with the aid of a calibration syringe (20 ml) and a rate of 30 min-1. The largest change in viscosity (11.6% at 22 degrees C and dry gas) is found with an increase in FiO2 (21...100%). A rise in temperature from 24 to 35 degrees C (dry air) produced an increase in viscosity of 5.2%. An increase of humidity (0...90%, 35 degrees C) decreased the viscosity by 3%. A partial compensation of these viscosity errors is thus possible. Pressure change (0...50 mbar, under ambient conditions) caused no measurable viscosity error. With the exception of temperature, the measurements have shown good agreement between the measured volume measuring errors and those calculated from viscosity changes. If the respiratory gas differs from ambient air (e.g. elevated FiO2) or if the PNT is calibrated under BTPS conditions, changes in viscosity must not be neglected when performing accurate ventilation measurements. On the basis of the well-known physical laws of Dalton, Thiesen and Sutherland, a numerical correction of adequate accuracy is possible.

Radial flow gas dynamic laser

International Nuclear Information System (INIS)

Damm, F.C.

1975-01-01

The unique gas dynamic laser provides outward radial supersonic flow from a toroidal shaped stacked array of a plurality of nozzles, through a diffuser having ring shaped and/or linear shaped vanes, and through a cavity which is cylindrical and concentric with the stacked array, with the resultant laser beam passing through the housing parallel to the central axis of the diffuser which is coincident with the axis of the gas dynamic laser. Therefore, greater beam extraction flexibility is attainable, because of fewer flow shock disturbances, as compared to the conventional unidirectional flow gas dynamic laser in which unidirectional supersonic flow sweeps through a rectangular cavity and is exhausted through a two-dimensional diffuser. (auth)

Extracting a respiratory signal from raw dynamic PET data that contain tracer kinetics.

Science.gov (United States)

Schleyer, P J; Thielemans, K; Marsden, P K

2014-08-07

Data driven gating (DDG) methods provide an alternative to hardware based respiratory gating for PET imaging. Several existing DDG approaches obtain a respiratory signal by observing the change in PET-counts within specific regions of acquired PET data. Currently, these methods do not allow for tracer kinetics which can interfere with the respiratory signal and introduce error. In this work, we produced a DDG method for dynamic PET studies that exhibit tracer kinetics. Our method is based on an existing approach that uses frequency-domain analysis to locate regions within raw PET data that are subject to respiratory motion. In the new approach, an optimised non-stationary short-time Fourier transform was used to create a time-varying 4D map of motion affected regions. Additional processing was required to ensure that the relationship between the sign of the respiratory signal and the physical direction of movement remained consistent for each temporal segment of the 4D map. The change in PET-counts within the 4D map during the PET acquisition was then used to generate a respiratory curve. Using 26 min dynamic cardiac NH3 PET acquisitions which included a hardware derived respiratory measurement, we show that tracer kinetics can severely degrade the respiratory signal generated by the original DDG method. In some cases, the transition of tracer from the liver to the lungs caused the respiratory signal to invert. The new approach successfully compensated for tracer kinetics and improved the correlation between the data-driven and hardware based signals. On average, good correlation was maintained throughout the PET acquisitions.

Extracting a respiratory signal from raw dynamic PET data that contain tracer kinetics

International Nuclear Information System (INIS)

Schleyer, P J; Thielemans, K; Marsden, P K

2014-01-01

Data driven gating (DDG) methods provide an alternative to hardware based respiratory gating for PET imaging. Several existing DDG approaches obtain a respiratory signal by observing the change in PET-counts within specific regions of acquired PET data. Currently, these methods do not allow for tracer kinetics which can interfere with the respiratory signal and introduce error. In this work, we produced a DDG method for dynamic PET studies that exhibit tracer kinetics. Our method is based on an existing approach that uses frequency-domain analysis to locate regions within raw PET data that are subject to respiratory motion. In the new approach, an optimised non-stationary short-time Fourier transform was used to create a time-varying 4D map of motion affected regions. Additional processing was required to ensure that the relationship between the sign of the respiratory signal and the physical direction of movement remained consistent for each temporal segment of the 4D map. The change in PET-counts within the 4D map during the PET acquisition was then used to generate a respiratory curve. Using 26 min dynamic cardiac NH 3 PET acquisitions which included a hardware derived respiratory measurement, we show that tracer kinetics can severely degrade the respiratory signal generated by the original DDG method. In some cases, the transition of tracer from the liver to the lungs caused the respiratory signal to invert. The new approach successfully compensated for tracer kinetics and improved the correlation between the data-driven and hardware based signals. On average, good correlation was maintained throughout the PET acquisitions. (paper)

Gas-controlled dynamic vacuum insulation with gas gate

Science.gov (United States)

Benson, D.K.; Potter, T.F.

1994-06-07

Disclosed is a dynamic vacuum insulation comprising sidewalls enclosing an evacuated chamber and gas control means for releasing hydrogen gas into a chamber to increase gas molecule conduction of heat across the chamber and retrieving hydrogen gas from the chamber. The gas control means includes a metal hydride that absorbs and retains hydrogen gas at cooler temperatures and releases hydrogen gas at hotter temperatures; a hydride heating means for selectively heating the metal hydride to temperatures high enough to release hydrogen gas from the metal hydride; and gate means positioned between the metal hydride and the chamber for selectively allowing hydrogen to flow or not to flow between said metal hydride and said chamber. 25 figs.

Event-by-Event Continuous Respiratory Motion Correction for Dynamic PET Imaging.

Science.gov (United States)

Yu, Yunhan; Chan, Chung; Ma, Tianyu; Liu, Yaqiang; Gallezot, Jean-Dominique; Naganawa, Mika; Kelada, Olivia J; Germino, Mary; Sinusas, Albert J; Carson, Richard E; Liu, Chi

2016-07-01

Existing respiratory motion-correction methods are applied only to static PET imaging. We have previously developed an event-by-event respiratory motion-correction method with correlations between internal organ motion and external respiratory signals (INTEX). This method is uniquely appropriate for dynamic imaging because it corrects motion for each time point. In this study, we applied INTEX to human dynamic PET studies with various tracers and investigated the impact on kinetic parameter estimation. The use of 3 tracers-a myocardial perfusion tracer, (82)Rb (n = 7); a pancreatic β-cell tracer, (18)F-FP(+)DTBZ (n = 4); and a tumor hypoxia tracer, (18)F-fluoromisonidazole ((18)F-FMISO) (n = 1)-was investigated in a study of 12 human subjects. Both rest and stress studies were performed for (82)Rb. The Anzai belt system was used to record respiratory motion. Three-dimensional internal organ motion in high temporal resolution was calculated by INTEX to guide event-by-event respiratory motion correction of target organs in each dynamic frame. Time-activity curves of regions of interest drawn based on end-expiration PET images were obtained. For (82)Rb studies, K1 was obtained with a 1-tissue model using a left-ventricle input function. Rest-stress myocardial blood flow (MBF) and coronary flow reserve (CFR) were determined. For (18)F-FP(+)DTBZ studies, the total volume of distribution was estimated with arterial input functions using the multilinear analysis 1 method. For the (18)F-FMISO study, the net uptake rate Ki was obtained with a 2-tissue irreversible model using a left-ventricle input function. All parameters were compared with the values derived without motion correction. With INTEX, K1 and MBF increased by 10% ± 12% and 15% ± 19%, respectively, for (82)Rb stress studies. CFR increased by 19% ± 21%. For studies with motion amplitudes greater than 8 mm (n = 3), K1, MBF, and CFR increased by 20% ± 12%, 30% ± 20%, and 34% ± 23%, respectively. For (82)Rb

Assessment of a volume-dependent dynamic respiratory system compliance in ALI/ARDS by pooling breathing cycles

International Nuclear Information System (INIS)

Zhao, Zhanqi; Möller, Knut; Guttmann, Josef

2012-01-01

New methods were developed to calculate the volume-dependent dynamic respiratory system compliance (C rs ) in mechanically ventilated patients. Due to noise in respiratory signals and different characteristics of the methods, their results can considerably differ. The aim of the study was to establish a practical procedure to validate the estimation of intratidal dynamic C rs . A total of 28 patients from intensive care units of eight German university hospitals with acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) were studied retrospectively. Dynamic volume-dependent C rs was determined during ongoing mechanical ventilation with the SLICE method, dynostatic algorithm and adaptive slice method. Conventional two-point compliance C 2P was calculated for comparison. A number of consecutive breathing cycles were pooled to reduce noise in the respiratory signals. C rs -volume curves produced with different methods converged when the number of pooling cycles increased (n ≥ 7). The mean volume-dependent C rs of 20 breaths was highly correlated with mean C 2P (C 2P,mean = 0.945 × C rs,mean − 0.053, r 2 = 0.968, p < 0.0001). The Bland–Altman analysis indicated that C 2P,mean was lower than C rs,mean (−2.4 ± 6.4 ml cm −1 H 2 O, mean bias ± 2 SD), but not significant according to the paired t-test (p > 0.05). Methods for analyzing dynamic respiratory mechanics are sensitive to noise and will converge to a unique solution when the number of pooled cycles increases. Under steady-state conditions, assessment of the volume-dependent C rs in ALI/ARDS patients can be validated by pooling respiratory data of consecutive breaths regardless of which method is applied. Confidence in dynamic C rs determination may be increased with the proposed pooling. (note)

Long-term effects of mustard gas on respiratory system of Iranian veterans after Iraq-Iran war: a review

Directory of Open Access Journals (Sweden)

Razavi Seyed Mansour

2013-06-01

Full Text Available 【Abstract】To review long-term respiratory effects of mustard gas on Iranian veterans having undergone Iraq-Iran war. Electronic databases of Scopus, Medline, ISI, IranMedex, and Irandoc sites were searched. We accepted articles published in scientific journals as a quality criterion. The main pathogenic factors are free radical mediators. Preva-lence of pulmonary involvement is approximately 42.5%. The most common complaints are cough and dyspnea. Major respiratory complications are chronic obstructive pulmo-nary disease, bronchiectasis, and asthma. Spirometry re-sults can reveal restrictive and obstructive pulmonary disease. Plain chest X-ray does not help in about 50% of lung diseases. High-resolution CT of the lung is the best modality for diagnostic assessment of parenchymal lung and bronchi. There is no definite curative treatment for mus-tard lung. The effective treatment regimens consist of oxy-gen administration, use of vaporized moist air, respiratory physiotherapy, administration of mucolytic agents, bronchodilators, corticosteroids, and long-acting beta-2 agonists, antioxidants, surfactant, magnesium ions, thera-peutic bronchoscopy, laser therapy, placement of respira-tory stents, early tracheostomy in laryngospasm, and ulti-mately lung transplantation. High-resolution CT of the lung is the most accurate modality for the evaluation of the lung parenchyma and bronchi. The treatment efficacy of patients exposed to mustard gas depends on patient conditions (acute or chronic, upper or lower respiratory tract involvement. There are various treatment protocols, but unfortunately none of them is definitely curable. Key words: Lung injury; Chemical warfare; Mustard gas

Respiratory motion artefacts in dynamic liver MRI: a comparison using gadoxetate disodium and gadobutrol

Energy Technology Data Exchange (ETDEWEB)

Luetkens, Julian A.; Kupczyk, Patrick A.; Doerner, Jonas; Willinek, Winfried A.; Schild, Hans H.; Kukuk, Guido M. [University of Bonn, Department of Radiology, Bonn (Germany); Fimmers, Rolf [University of Bonn, Department of Medical Biometry, Informatics, and Epidemiology, Bonn (Germany)

2015-11-15

Our aim was to retrospectively evaluate the occurrence of respiratory motion artefacts in patients undergoing dynamic liver magnetic resonance (MR) either with gadoxetate disodium or gadobutrol. Two hundred and thirty liver MR studies (115 with gadobutrol, 115 with gadoxetate disodium) were analysed. Respiratory motion artefacts on dynamic 3D T1-weighted MR images (pre-contrast, arterial, venous, and late-dynamic phase) were assessed using a five-point rating scale. Severe motion was defined as a score ≥ 4. Mean motion scores were compared with the Mann-Whitney-U-test. The chi-squared-test was used for dichotomous comparisons. Mean motion scores for gadoxetate disodium and gadobutrol showed no relevant differences for each phase of the dynamic contrast series (pre-contrast: 1.85 ± 0.70 vs. 1.88 ± 0.57, arterial: 1.85 ± 0.81 vs. 1.87 ± 0.74, venous: 1.82 ± 0.67 vs. 1.74 ± 0.64, late-dynamic: 1.75 ± 0.62 vs. 1.79 ± 0.63; p = 0.469, 0.557, 0.382 and 0.843, respectively). Severe motion artefacts had a similar incidence using gadoxetate disodium and gadobutrol (11/460 [2.4 %] vs. 7/460 [1.5 %]; p = 0.341). Gadoxetate disodium is associated with equivalent motion scores compared to gadobutrol in dynamic liver MRI. In addition, both contrast agents demonstrated a comparable and acceptable rate of severe respiratory motion artefacts. (orig.)

Modern problems of relaxation gas dynamics

International Nuclear Information System (INIS)

Losev, S.A.; Osipov, A.I.

1985-01-01

Some of the dynamical characteristics of relaxation processes are studied. Unfortunately, many dynamical characteristics of relaxation processes, necessary for the solution of important scientific and applied problems, are not known. These problems require further development of experimental methods of the study of nonequilibrium gas. It is known, that gas systems are shifted from the equilibrium by different methods: by acoustic and shock wav es, by means of gas expansion in nozzles and jets, by powerful radiations (laser, first of all), by electric discharges, in burning and combustion devices, etc. Non-equilibrium gas is produced in installations of continuum, impulse and periodic regime. Molecular beams, shock tubes (especially with nozzles), flow and jet installations, aerodynamical tubes, plasmatrons, vessels with a gas, influenced by the strong radiation, burners and combustion devices, where the study of non-euilibrium gas is helpful to solve the problems of the determination of kinetic equations and constants of physico-chemical kinetics

Gas dynamic laser device

International Nuclear Information System (INIS)

Born, G.

1975-01-01

The gas dynamic laser device is provided with an expansion chamber arranged between a heating chamber for the CO-gas and the resonance chamber. The expansion chamber is initially evacuated for producing a rarefaction wave. Between the heating chamber and the expansion chamber there are arranged rapid release means such as a valve or a diaphragm. Pressure recovering means are connected to the other side of the resonance chamber

Fifty Years of Research in ARDS. Gas Exchange in Acute Respiratory Distress Syndrome.

Science.gov (United States)

Radermacher, Peter; Maggiore, Salvatore Maurizio; Mercat, Alain

2017-10-15

Acute respiratory distress syndrome (ARDS) is characterized by severe impairment of gas exchange. Hypoxemia is mainly due to intrapulmonary shunt, whereas increased alveolar dead space explains the alteration of CO 2 clearance. Assessment of the severity of gas exchange impairment is a requisite for the characterization of the syndrome and the evaluation of its severity. Confounding factors linked to hemodynamic status can greatly influence the relationship between the severity of lung injury and the degree of hypoxemia and/or the effects of ventilator settings on gas exchange. Apart from situations of rescue treatment, targeting optimal gas exchange in ARDS has become less of a priority compared with prevention of injury. A complex question for clinicians is to understand when improvement in oxygenation and alveolar ventilation is related to a lower degree or risk of injury for the lungs. In this regard, a full understanding of gas exchange mechanism in ARDS is imperative for individualized symptomatic support of patients with ARDS.

Respiratory involvements among women exposed to the smoke of traditional biomass fuel and gas fuel in a district of Bangladesh.

Science.gov (United States)

Alim, Md Abdul; Sarker, Mohammad Abul Bashar; Selim, Shahjada; Karim, Md Rizwanul; Yoshida, Yoshitoku; Hamajima, Nobuyuki

2014-03-01

Burning of biomass fuel (cow-dung, crop residue, dried leaves, wood, etc.) in the kitchen releases smoke, which may impair the respiratory functions of women cooking there. This paper aimed to compare the respiratory symptoms between biomass fuel users and gas fuel users in Bangladesh. A cross-sectional survey was conducted through face-to-face interviews and chest examination of 224 adult women using biomass fuel in a rural village and 196 adult women using gas fuel in an urban area. The prevalence of respiratory involvement (at least one among nine symptoms and two diseases) was significantly higher among biomass users than among gas users (29.9 vs. 11.2 %). After adjustment for potential confounders by a logistic model, the odds ratio (OR) of the biomass users for the respiratory involvement was significantly higher (OR = 3.23, 95 % confidence interval 1.30-8.01). The biomass fuel use elevated symptoms/diseases significantly; the adjusted OR was 3.04 for morning cough, 7.41 for nasal allergy, and 5.94 for chronic bronchitis. The mean peak expiratory flow rate of biomass users (253.83 l/min) was significantly lower than that of gas users (282.37 l/min). The study shows significant association between biomass fuel use and respiratory involvement among rural women in Bangladesh, although the potential confounding of urban/rural residency could not be ruled out in the analysis. The use of smoke-free stoves and adequate ventilation along with health education to the rural population to increase awareness about the health effects of indoor biomass fuel use might have roles to prevent these involvements.

Respiratory system dynamical mechanical properties: modeling in time and frequency domain.

Science.gov (United States)

Carvalho, Alysson Roncally; Zin, Walter Araujo

2011-06-01

The mechanical properties of the respiratory system are important determinants of its function and can be severely compromised in disease. The assessment of respiratory system mechanical properties is thus essential in the management of some disorders as well as in the evaluation of respiratory system adaptations in response to an acute or chronic process. Most often, lungs and chest wall are treated as a linear dynamic system that can be expressed with differential equations, allowing determination of the system's parameters, which will reflect the mechanical properties. However, different models that encompass nonlinear characteristics and also multicompartments have been used in several approaches and most specifically in mechanically ventilated patients with acute lung injury. Additionally, the input impedance over a range of frequencies can be assessed with a convenient excitation method allowing the identification of the mechanical characteristics of the central and peripheral airways as well as lung periphery impedance. With the evolution of computational power, the airway pressure and flow can be recorded and stored for hours, and hence continuous monitoring of the respiratory system mechanical properties is already available in some mechanical ventilators. This review aims to describe some of the most frequently used models for the assessment of the respiratory system mechanical properties in both time and frequency domain.

Reduction of gas flow nonuniformity in gas turbine engines by means of gas-dynamic methods

Science.gov (United States)

Matveev, V.; Baturin, O.; Kolmakova, D.; Popov, G.

2017-08-01

Gas flow nonuniformity is one of the main sources of rotor blade vibrations in the gas turbine engines. Usually, the flow circumferential nonuniformity occurs near the annular frames, located in the flow channel of the engine. This leads to the increased dynamic stresses in blades and as a consequence to the blade damage. The goal of the research was to find an acceptable method of reducing the level of gas flow nonuniformity as the source of dynamic stresses in the rotor blades. Two different methods were investigated during this research. Thus, this study gives the ideas about methods of improving the flow structure in gas turbine engine. On the basis of existing conditions (under development or existing engine) it allows the selection of the most suitable method for reducing gas flow nonuniformity.

Chaotic dynamics of respiratory sounds

International Nuclear Information System (INIS)

Ahlstrom, C.; Johansson, A.; Hult, P.; Ask, P.

2006-01-01

There is a growing interest in nonlinear analysis of respiratory sounds (RS), but little has been done to justify the use of nonlinear tools on such data. The aim of this paper is to investigate the stationarity, linearity and chaotic dynamics of recorded RS. Two independent data sets from 8 + 8 healthy subjects were recorded and investigated. The first set consisted of lung sounds (LS) recorded with an electronic stethoscope and the other of tracheal sounds (TS) recorded with a contact accelerometer. Recurrence plot analysis revealed that both LS and TS are quasistationary, with the parts corresponding to inspiratory and expiratory flow plateaus being stationary. Surrogate data tests could not provide statistically sufficient evidence regarding the nonlinearity of the data. The null hypothesis could not be rejected in 4 out of 32 LS cases and in 15 out of 32 TS cases. However, the Lyapunov spectra, the correlation dimension (D 2 ) and the Kaplan-Yorke dimension (D KY ) all indicate chaotic behavior. The Lyapunov analysis showed that the sum of the exponents was negative in all cases and that the largest exponent was found to be positive. The results are partly ambiguous, but provide some evidence of chaotic dynamics of RS, both concerning LS and TS. The results motivate continuous use of nonlinear tools for analysing RS data

Chaotic dynamics of respiratory sounds

Energy Technology Data Exchange (ETDEWEB)

Ahlstrom, C. [Department of Biomedical Engineering, Linkoepings Universitet, IMT/LIU, Universitetssjukhuset, S-58185 Linkoeping (Sweden) and Biomedical Engineering, Orebro University Hospital, S-70185 Orebro (Sweden)]. E-mail: christer@imt.liu.se; Johansson, A. [Department of Biomedical Engineering, Linkoepings Universitet, IMT/LIU, Universitetssjukhuset, S-58185 Linkoeping (Sweden); Hult, P. [Department of Biomedical Engineering, Linkoepings Universitet, IMT/LIU, Universitetssjukhuset, S-58185 Linkoeping (Sweden); Biomedical Engineering, Orebro University Hospital, S-70185 Orebro (Sweden); Ask, P. [Department of Biomedical Engineering, Linkoepings Universitet, IMT/LIU, Universitetssjukhuset, S-58185 Linkoeping (Sweden); Biomedical Engineering, Orebro University Hospital, S-70185 Orebro (Sweden)

2006-09-15

There is a growing interest in nonlinear analysis of respiratory sounds (RS), but little has been done to justify the use of nonlinear tools on such data. The aim of this paper is to investigate the stationarity, linearity and chaotic dynamics of recorded RS. Two independent data sets from 8 + 8 healthy subjects were recorded and investigated. The first set consisted of lung sounds (LS) recorded with an electronic stethoscope and the other of tracheal sounds (TS) recorded with a contact accelerometer. Recurrence plot analysis revealed that both LS and TS are quasistationary, with the parts corresponding to inspiratory and expiratory flow plateaus being stationary. Surrogate data tests could not provide statistically sufficient evidence regarding the nonlinearity of the data. The null hypothesis could not be rejected in 4 out of 32 LS cases and in 15 out of 32 TS cases. However, the Lyapunov spectra, the correlation dimension (D {sub 2}) and the Kaplan-Yorke dimension (D {sub KY}) all indicate chaotic behavior. The Lyapunov analysis showed that the sum of the exponents was negative in all cases and that the largest exponent was found to be positive. The results are partly ambiguous, but provide some evidence of chaotic dynamics of RS, both concerning LS and TS. The results motivate continuous use of nonlinear tools for analysing RS data.

A dynamic population-based model for the development of work-related respiratory health effects among bakery workers.

NARCIS (Netherlands)

Warren, N.; Meijster, T.; Heederik, D.; Tielemans, E.

2009-01-01

OBJECTIVES: This paper presents a dynamic population-based model for the development of sensitisation and respiratory symptoms in bakery workers. The model simulates a population of individual workers longitudinally and tracks the development of work-related sensitisation and respiratory symptoms in

A dynamic population-based model for the development of work-related respiratory health effects among bakery workers

NARCIS (Netherlands)

Warren, N.; Meijster, T.; Heederik, D.; Tielemans, E.

2009-01-01

Objectives: This paper presents a dynamic population-based model for the development of sensitisation and respiratory symptoms in bakery workers. The model simulates a population of individual workers longitudinally and tracks the development of work-related sensitisation and respiratory symptoms in

Interaction between gas cooking and GSTM1 null genotype in bronchial responsiveness: results from the European Community Respiratory Health Survey.

NARCIS (Netherlands)

Amaral, A.F.S.; Ramasamy, A.; Castro-Giner, F.; Minelli, C.; Accordini, S.; Sorheim, I.C.; Pin, I.; Kogevinas, M.; Jögi, R.; Balding, D.J.; Norbäck, D.; Verlato, G.; Olivieri, M.; Probst-Hensch, N.; Janson, C.; Zock, J.P.; Heinrich, J.; Jarvis, D.L.

2014-01-01

Background: Increased bronchial responsiveness is characteristic of asthma. Gas cooking, which is a major indoor source of the highly oxidant nitrogen dioxide, has been associated with respiratory symptoms and reduced lung function. However, little is known about the effect of gas cooking on

Effects of Gas Dynamics on Rapidly Collapsing Bubbles

OpenAIRE

Bauman, Spenser; Fomitchev-Zamilov, Max

2013-01-01

The dynamics of rapidly collapsing bubbles are of great interest due to the high degree of energy focusing that occurs withing the bubble. Molecular dynamics provides a way to model the interior of the bubble and couple the gas dynamics with the equations governing the bubble wall. While much theoretical work has been done to understand how a bubble will respond to an external force, the internal dynamics of the gas system are usually simplified greatly in such treatments. This paper shows ho...

Computational modeling of intraocular gas dynamics

International Nuclear Information System (INIS)

Noohi, P; Abdekhodaie, M J; Cheng, Y L

2015-01-01

The purpose of this study was to develop a computational model to simulate the dynamics of intraocular gas behavior in pneumatic retinopexy (PR) procedure. The presented model predicted intraocular gas volume at any time and determined the tolerance angle within which a patient can maneuver and still gas completely covers the tear(s). Computational fluid dynamics calculations were conducted to describe PR procedure. The geometrical model was constructed based on the rabbit and human eye dimensions. SF_6 in the form of pure and diluted with air was considered as the injected gas. The presented results indicated that the composition of the injected gas affected the gas absorption rate and gas volume. After injection of pure SF_6, the bubble expanded to 2.3 times of its initial volume during the first 23 h, but when diluted SF_6 was used, no significant expansion was observed. Also, head positioning for the treatment of retinal tear influenced the rate of gas absorption. Moreover, the determined tolerance angle depended on the bubble and tear size. More bubble expansion and smaller retinal tear caused greater tolerance angle. For example, after 23 h, for the tear size of 2 mm the tolerance angle of using pure SF_6 is 1.4 times more than that of using diluted SF_6 with 80% air. Composition of the injected gas and conditions of the tear in PR may dramatically affect the gas absorption rate and gas volume. Quantifying these effects helps to predict the tolerance angle and improve treatment efficiency. (paper)

Elements of gas dynamics

CERN Document Server

Liepmann, H W

2001-01-01

The increasing importance of concepts from compressible fluid flow theory for aeronautical applications makes the republication of this first-rate text particularly timely. Intended mainly for aeronautics students, the text will also be helpful to practicing engineers and scientists who work on problems involving the aerodynamics of compressible fluids. Covering the general principles of gas dynamics to provide a working understanding of the essentials of gas flow, the contents of this book form the foundation for a study of the specialized literature and should give the necessary background

Transient dynamic crack propagation in gas pressurised pipelines

International Nuclear Information System (INIS)

Caldis, E.S.; Owen, D.R.J.; Taylor, C.

1983-01-01

The prime limitation of dynamic fracture analysis is the lack of a fundamental crack advance theory which can be easily and economically adopted for use with numerical models. The necessity for the inclusion of inertia effects in the solution of certain problem classes is now evident, but most transient dynamic fracture models considered to date include (of necessity) some intuitive/empirical parameters with a frequent need of a priori knowledge of experimental solutions. The particular problem considered in this study is Mode I transient dynamic crack propagation in gas pressurised pipelines. The steel pipe is modelled using thin shell Semiloof finite elements and its transient response is coupled to a one-dimensional finite element model of the compressible gas equations, incorporating a lateral gas flow parameter. The pipe is governed by the usual dynamic equilibrium equation which is discretised in the time domain by a central difference explicit algorithm. The compressible gas response is modelled by the Continuity and Momentum equations and time discretisation is performed by means of a fully backward difference scheme in time. (orig./GL)

A comparative meta-analysis of maximal aerobic metabolism of vertebrates: implications for respiratory and cardiovascular limits to gas exchange.

Science.gov (United States)

Hillman, Stanley S; Hancock, Thomas V; Hedrick, Michael S

2013-02-01

Maximal aerobic metabolic rates (MMR) in vertebrates are supported by increased conductive and diffusive fluxes of O(2) from the environment to the mitochondria necessitating concomitant increases in CO(2) efflux. A question that has received much attention has been which step, respiratory or cardiovascular, provides the principal rate limitation to gas flux at MMR? Limitation analyses have principally focused on O(2) fluxes, though the excess capacity of the lung for O(2) ventilation and diffusion remains unexplained except as a safety factor. Analyses of MMR normally rely upon allometry and temperature to define these factors, but cannot account for much of the variation and often have narrow phylogenetic breadth. The unique aspect of our comparative approach was to use an interclass meta-analysis to examine cardio-respiratory variables during the increase from resting metabolic rate to MMR among vertebrates from fish to mammals, independent of allometry and phylogeny. Common patterns at MMR indicate universal principles governing O(2) and CO(2) transport in vertebrate cardiovascular and respiratory systems, despite the varied modes of activities (swimming, running, flying), different cardio-respiratory architecture, and vastly different rates of metabolism (endothermy vs. ectothermy). Our meta-analysis supports previous studies indicating a cardiovascular limit to maximal O(2) transport and also implicates a respiratory system limit to maximal CO(2) efflux, especially in ectotherms. Thus, natural selection would operate on the respiratory system to enhance maximal CO(2) excretion and the cardiovascular system to enhance maximal O(2) uptake. This provides a possible evolutionary explanation for the conundrum of why the respiratory system appears functionally over-designed from an O(2) perspective, a unique insight from previous work focused solely on O(2) fluxes. The results suggest a common gas transport blueprint, or Bauplan, in the vertebrate clade.

Differential Effects of Endotracheal Suctioning on Gas Exchanges in Patients with Acute Respiratory Failure under Pressure-Controlled and Volume-Controlled Ventilation

Directory of Open Access Journals (Sweden)

Xiao-Wei Liu

2015-01-01

Full Text Available This study was conducted to evaluate the effects of open endotracheal suctioning on gas exchange and respiratory mechanics in ARF patients under the modes of PCV or VCV. Ninety-six ARF patients were treated with open endotracheal suctioning and their variations in respiratory mechanics and gas exchange after the suctions were compared. Under PCV mode, compared with the initial level of tidal volume (VT, ARF patients showed 30.0% and 27.8% decrease at 1 min and 10 min, respectively. Furthermore, the initial respiratory system compliance (Crs decreased by 29.6% and 28.5% at 1 min and 10 min, respectively. Under VCV mode, compared with the initial level, 38.6% and 37.5% increase in peak airway pressure (PAP were found at 1 min and 10 min, respectively. Under PCV mode, the initial PaO2 increased by 6.4% and 10.2 % at 3 min and 10 min, respectively, while 18.9% and 30.6% increase of the initial PaO2 were observed under VCV mode. Summarily, endotracheal suctioning may impair gas exchange and decrease lung compliance in ARF patients receiving mechanical ventilation under both PCV and VCV modes, but endotracheal suctioning effects on gas exchange were more severe and longer-lasting under PCV mode than VCV.

33 CFR 127.1209 - Respiratory protection.

Science.gov (United States)

2010-07-01

... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Respiratory protection. 127.1209... Waterfront Facilities Handling Liquefied Hazardous Gas Equipment § 127.1209 Respiratory protection. Each waterfront facility handling LHG must provide equipment for respiratory protection for each employee of the...

Cloud-particle galactic gas dynamics and star formation

International Nuclear Information System (INIS)

Roberts, W.W. Jr.

1983-01-01

Galactic gas dynamics, spiral structure, and star formation are discussed in the context of N-body computational studies based on a cloud-particle model of the interstellar medium. On the small scale, the interstellar medium appears to be cloud-dominated and supernova-perturbed. The cloud-particle model simulates cloud-cloud collisions, the formation of stellar associations, and supernova explosions as dominant local processes. On the large scale in response to a spiral galactic gravitational field, global density waves and galactic shocks develop with large-scale characteristics similar to those found in continuum gas dynamical studies. Both the system of gas clouds and the system of young stellar associations forming from the clouds share in the global spiral structure. However, with the attributes of neither assuming a continuum of gas (as in continuum gas dynamical studies) nor requiring a prescribed equation of state such as the isothermal condition so often employed, the cloud-particle picture retains much of the detail lost in earlier work: namely, the small-scale features and structures so important in understanding the local, turbulent state of the interstellar medium as well as the degree of raggedness often observed superposed on global spiral structure. (Auth.)

Systems of quasilinear equations and their applications to gas dynamics

CERN Document Server

Roždestvenskiĭ, B L; Schulenberger, J R

1983-01-01

This book is essentially a new edition, revised and augmented by results of the last decade, of the work of the same title published in 1968 by "Nauka." It is devoted to mathematical questions of gas dynamics. Topics covered include Foundations of the Theory of Systems of Quasilinear Equations of Hyperbolic Type in Two Independent Variables; Classical and Generalized Solutions of One-Dimensional Gas Dynamics; Difference Methods for Solving the Equations of Gas Dynamics; and Generalized Solutions of Systems of Quasilinear Equations of Hyperbolic Type.

Dynamic PET image reconstruction integrating temporal regularization associated with respiratory motion correction for applications in oncology

Science.gov (United States)

Merlin, Thibaut; Visvikis, Dimitris; Fernandez, Philippe; Lamare, Frédéric

2018-02-01

Respiratory motion reduces both the qualitative and quantitative accuracy of PET images in oncology. This impact is more significant for quantitative applications based on kinetic modeling, where dynamic acquisitions are associated with limited statistics due to the necessity of enhanced temporal resolution. The aim of this study is to address these drawbacks, by combining a respiratory motion correction approach with temporal regularization in a unique reconstruction algorithm for dynamic PET imaging. Elastic transformation parameters for the motion correction are estimated from the non-attenuation-corrected PET images. The derived displacement matrices are subsequently used in a list-mode based OSEM reconstruction algorithm integrating a temporal regularization between the 3D dynamic PET frames, based on temporal basis functions. These functions are simultaneously estimated at each iteration, along with their relative coefficients for each image voxel. Quantitative evaluation has been performed using dynamic FDG PET/CT acquisitions of lung cancer patients acquired on a GE DRX system. The performance of the proposed method is compared with that of a standard multi-frame OSEM reconstruction algorithm. The proposed method achieved substantial improvements in terms of noise reduction while accounting for loss of contrast due to respiratory motion. Results on simulated data showed that the proposed 4D algorithms led to bias reduction values up to 40% in both tumor and blood regions for similar standard deviation levels, in comparison with a standard 3D reconstruction. Patlak parameter estimations on reconstructed images with the proposed reconstruction methods resulted in 30% and 40% bias reduction in the tumor and lung region respectively for the Patlak slope, and a 30% bias reduction for the intercept in the tumor region (a similar Patlak intercept was achieved in the lung area). Incorporation of the respiratory motion correction using an elastic model along with a

Evaluation of exercise-respiratory system modifications and preliminary respiratory-circulatory system integration scheme

Science.gov (United States)

Gallagher, R. R.

1974-01-01

The respiratory control system, functioning as an independent system, is presented with modifications of the exercise subroutine. These modifications illustrate an improved control of ventilation rates and arterial and compartmental gas tensions. A very elementary approach to describing the interactions of the respiratory and circulatory system is presented.

Ideal gas approximation for a two-dimensional rarefied gas under Kawasaki dynamics

NARCIS (Netherlands)

Gaudillière, A.; Hollander, den W.Th.F.; Nardi, F.R.; Olivieri, E.; Scoppola, E.

2009-01-01

In this paper we consider a two-dimensional lattice gas under Kawasaki dynamics, i.e., particles hop around randomly subject to hard-core repulsion and nearest-neighbor attraction. We show that, at fixed temperature and in the limit as the particle density tends to zero, such a gas evolves in a way

The computer simulation of 3d gas dynamics in a gas centrifuge

Science.gov (United States)

Borman, V. D.; Bogovalov, S. V.; Borisevich, V. D.; Tronin, I. V.; Tronin, V. N.

2016-09-01

We argue on the basis of the results of 2D analysis of the gas flow in gas centrifuges that a reliable calculation of the circulation of the gas and gas content in the gas centrifuge is possible only in frameworks of 3D numerical simulation of gas dynamics in the gas centrifuge (hereafter GC). The group from National research nuclear university, MEPhI, has created a computer code for 3D simulation of the gas flow in GC. The results of the computer simulations of the gas flows in GC are presented. A model Iguassu centrifuge is explored for the simulations. A nonaxisymmetric gas flow is produced due to interaction of the hypersonic rotating flow with the scoops for extraction of the product and waste flows from the GC. The scoops produce shock waves penetrating into a working camera of the GC and form spiral waves there.

The computer simulation of 3d gas dynamics in a gas centrifuge

International Nuclear Information System (INIS)

Borman, V D; Bogovalov, S V; Borisevich, V D; Tronin, I V; Tronin, V N

2016-01-01

We argue on the basis of the results of 2D analysis of the gas flow in gas centrifuges that a reliable calculation of the circulation of the gas and gas content in the gas centrifuge is possible only in frameworks of 3D numerical simulation of gas dynamics in the gas centrifuge (hereafter GC). The group from National research nuclear university, MEPhI, has created a computer code for 3D simulation of the gas flow in GC. The results of the computer simulations of the gas flows in GC are presented. A model Iguassu centrifuge is explored for the simulations. A nonaxisymmetric gas flow is produced due to interaction of the hypersonic rotating flow with the scoops for extraction of the product and waste flows from the GC. The scoops produce shock waves penetrating into a working camera of the GC and form spiral waves there. (paper)

Research Summary 3-D Computational Fluid Dynamics (CFD) Model Of The Human Respiratory System

Science.gov (United States)

The U.S. EPA’s Office of Research and Development (ORD) has developed a 3-D computational fluid dynamics (CFD) model of the human respiratory system that allows for the simulation of particulate based contaminant deposition and clearance, while being adaptable for age, ethnicity,...

Spin dynamics in a two-dimensional quantum gas

DEFF Research Database (Denmark)

Pedersen, Poul Lindholm; Gajdacz, Miroslav; Deuretzbacher, Frank

2014-01-01

We have investigated spin dynamics in a two-dimensional quantum gas. Through spin-changing collisions, two clouds with opposite spin orientations are spontaneously created in a Bose-Einstein condensate. After ballistic expansion, both clouds acquire ring-shaped density distributions with superimp......We have investigated spin dynamics in a two-dimensional quantum gas. Through spin-changing collisions, two clouds with opposite spin orientations are spontaneously created in a Bose-Einstein condensate. After ballistic expansion, both clouds acquire ring-shaped density distributions...

Molecular dynamics of Middle East Respiratory Syndrome Coronavirus (MERS CoV) fusion heptad repeat trimers

KAUST Repository

Kandeel, Mahmoud; Al-Taher, Abdulla; Li, Huifang; Schwingenschlö gl, Udo; Alnazawi, Mohamed

2018-01-01

Structural studies related to Middle East Respiratory Syndrome Coronavirus (MERS CoV) infection process are so limited. In this study, molecular dynamics (MD) simulation was carried out to unravel changes in the MERS CoV heptad repeat domains (HRs

Respiratory analysis system and method

Science.gov (United States)

Liu, F. F. (Inventor)

1973-01-01

A system is described for monitoring the respiratory process in which the gas flow rate and the frequency of respiration and expiration cycles can be determined on a real time basis. A face mask is provided with one-way inlet and outlet valves where the gas flow is through independent flowmeters and through a mass spectrometer. The opening and closing of a valve operates an electrical switch, and the combination of the two switches produces a low frequency electrical signal of the respiratory inhalation and exhalation cycles. During the time a switch is operated, the corresponsing flowmeter produces electric pulses representative of the flow rate; the electrical pulses being at a higher frequency than that of the breathing cycle and combined with the low frequency signal. The high frequency pulses are supplied to conventional analyzer computer which also receives temperature and pressure inputs and computes mass flow rate and totalized mass flow of gas. From the mass spectrometer, components of the gas are separately computed as to flow rate. The electrical switches cause operation of up-down inputs of a reversible counter. The respective up and down cycles can be individually monitored and combined for various respiratory measurements.

Gas-Dynamic Methods to Reduce Gas Flow Nonuniformity from the Annular Frames of Gas Turbine Engines

Science.gov (United States)

Kolmakova, D.; Popov, G.

2018-01-01

Gas flow nonuniformity is one of the main sources of rotor blade vibrations in the gas turbine engines. Usually, the flow circumferential nonuniformity occurs near the annular frames, located in the flow channel of the engine. This leads to the increased dynamic stresses in blades and consequently to the blade damage. The goal of the research was to find an acceptable method of reducing the level of gas flow nonuniformity. Two different methods were investigated during this research. Thus, this study gives the ideas about methods of improving the flow structure in gas turbine engine. Based on existing conditions (under development or existing engine) it allows the selection of the most suitable method for reducing gas flow nonuniformity.

Reduction of motion artifacts for PET imaging by respiratory correlated dynamic scanning

International Nuclear Information System (INIS)

Chuang, K.-S.; Chen, T.-J.; Chang, C.-C.; Wu, J.; Chen, S.; Wu, L.-C.; Liu, R.-S.

2006-01-01

Organ motion caused by respiration is a major challenge in positron emission tomography (PET) imaging. This work proposes a technique to reduce smearing in PET imaging caused by respiratory motion. Dynamic scanning at 1 frame/s is used. A point source, used as a marker, is attached to the object's abdomen during the scan. The source position in the projection view moves with respiratory motion and can be used to represent the respiratory phase within the time interval in which each frame data are acquired. One hundred and twenty frames are obtained for each study. The range of the positions of the marker is divided into four groups, representing different respiratory phases. The frames in which the organ positions (phases) are the same summed to produce a static sub-sinogram. Each sub-sinogram then undergoes regular image reconstruction to yield a motion-free image. The technique is applied to one volunteer under both free and coached breathing conditions. A parameter called the volume reduction factor is adopted to evaluate the effectiveness of this motion-reduction technique. The preliminary results indicate that the proposed technique effectively reduces motion artifacts in the image. Coached breathing yields better results than free breathing condition. The advantages of this method are that (1) the scanning time remains the same; (2) free breathing is allowed during the acquisition of the image; and (3) no user intervention is required

Canadian natural gas market: dynamics and pricing

International Nuclear Information System (INIS)

2000-01-01

This publication by the National Energy Board is part of a continuing program of assessing applications for long-term natural gas export licences. The market-based procedure used by the Board is based on the premise that the marketplace will generally operate in a way that will ensure that Canadian requirements for natural gas will be met at fair market prices. The market--based procedure consists of a public hearing and a monitoring component. The monitoring component involves the on-going assessment of Canadian energy markets to provide analyses of major energy commodities on either an individual or integrated commodity basis. This report is the result of the most recent assessment . It identifies factors that affect natural gas prices and describes the functioning of regional markets in Canada. It provides an overview of the energy demand, including recent trends, reviews the North American gas supply and markets, the natural gas pricing dynamics in Canada, and a regional analysis of markets, prices and dynamics in British Columbia, Alberta, Saskatchewan, Manitoba, Ontario, Quebec and the Atlantic provinces. In general, demand growth outstripped growth in supply, but natural gas producers throughout North America have been responding to the current high price environment with aggressive drilling programs. The Board anticipates that in time, there will be a supply and demand response and accompanying relief in natural gas prices. A review of the annual weighted average border price paid for Alberta gas indicates that domestic gas users paid less than export customers until 1998, at which point the two prices converged, suggesting that Canadians have had access to natural gas at prices no less favourable than export customers. The influence of electronic trading systems such as NYMEX and AECO-C/NIT have had significant impact on the pricing of natural gas. These systems, by providing timely information to market participants. enables them to manage price

Gas dynamics in strong centrifugal fields

OpenAIRE

Bogovalov, S. V.; Kislov, V. A.; Tronin, I. V.

2017-01-01

Dynamics of waves generated by scopes in gas centrifuges (GC) for isotope separation is considered. The centrifugal acceleration in the GC reaches values of the order of $10^6$g. The centrifugal and Coriolis forces modify essentially the conventional sound waves. Three families of the waves with different polarisation and dispersion exist in these conditions. Dynamics of the flow in the model GC Iguasu is investigated numerically. Comparison of the results of the numerical modelling of the wa...

Dynamic pressure as a measure of gas turbine engine (GTE) performance

International Nuclear Information System (INIS)

Rinaldi, G; Stiharu, I; Packirisamy, M; Nerguizian, V; Landry, R Jr; Raskin, J-P

2010-01-01

Utilizing in situ dynamic pressure measurement is a promising novel approach with applications for both control and condition monitoring of gas turbine-based propulsion systems. The dynamic pressure created by rotating components within the engine presents a unique opportunity for controlling the operation of the engine and for evaluating the condition of a specific component through interpretation of the dynamic pressure signal. Preliminary bench-top experiments are conducted with dc axial fans for measuring fan RPM, blade condition, surge and dynamic temperature variation. Also, a method, based on standing wave physics, is presented for measuring the dynamic temperature simultaneously with the dynamic pressure. These tests are implemented in order to demonstrate the versatility of dynamic pressure-based diagnostics for monitoring several different parameters, and two physical quantities, dynamic pressure and dynamic temperature, with a single sensor. In this work, the development of a dynamic pressure sensor based on micro-electro-mechanical system technology for in situ gas turbine engine condition monitoring is presented. The dynamic pressure sensor performance is evaluated on two different gas turbine engines, one having a fan and the other without

Key factors of combustion from kinetics to gas dynamics

CERN Document Server

Rubtsov, Nikolai M

2017-01-01

This book summarizes the main advances in the mechanisms of combustion processes. It focuses on the analysis of kinetic mechanisms of gas combustion processes and experimental investigation into the interrelation of kinetics and gas dynamics in gas combustion. The book is complimentary to the one previously published, The Modes of Gaseous Combustion.

Automated respiratory support in newborn infants.

Science.gov (United States)

Claure, Nelson; Bancalari, Eduardo

2009-02-01

A considerable proportion of premature infants requires mechanical ventilatory support and supplemental oxygen. Due to their immaturity, exposure to these forms of respiratory support contributes to the development of lung injury, oxidative stress and abnormal retinal development. These conditions are associated with poor long-term respiratory and neurological outcome. Mechanically ventilated preterm infants present with frequent fluctuations in ventilation and gas exchange. Currently available ventilatory modes and manual adjustment to the ventilator or supplemental oxygen cannot effectively adapt to these recurrent fluctuations. Moreover, the respiratory support often exceeds the infant's real needs. Techniques that adapt the mechanical ventilatory support and supplemental oxygen to the changing needs of preterm infants are being developed in order to improve stability of gas exchange, to minimise respiratory support and to reduce personnel workload. This article describes the preliminary evidence on the application of these new techniques in preterm infants and animal models.

Gas-liquid reactor / separator: dynamics and operability characteristics

NARCIS (Netherlands)

Ranade, V.; Kuipers, J.A.M.; Versteeg, Geert

1999-01-01

A comprehensive mathematical model is developed to simulate gas¿liquid reactor in which both, reactants as well as products enter or leave the reactor in gas phase while the reactions take place in liquid phase. A case of first-order reaction (isothermal) was investigated in detail using the dynamic

Gas-Phase Molecular Dynamics: Theoretical Studies in Spectroscopy and Chemical Dynamics

Energy Technology Data Exchange (ETDEWEB)

Yu, H.G.; Muckerman, J.T.

2010-06-01

The goal of this program is the development and application of computational methods for studying chemical reaction dynamics and molecular spectroscopy in the gas phase. We are interested in developing rigorous quantum dynamics algorithms for small polyatomic systems and in implementing approximate approaches for complex ones. Particular focus is on the dynamics and kinetics of chemical reactions and on the rovibrational spectra of species involved in combustion processes. This research also explores the potential energy surfaces of these systems of interest using state-of-the-art quantum chemistry methods.

Diagnosis of tracheomalacia using tracheal dynamic respiratory-scan

International Nuclear Information System (INIS)

Matsui, Teruo; Watabe, Hideki; Ikeda, Sadao

1995-01-01

We performed tracheal-dynamic respiratory scan (T-DRS) in 54 cases which were thought to be tracheomalacia clinically. T-DRS was performed by TOSHIBA TCT-900S at the level of the aortic arch under the condition of 120 kV (140 kV), 100 mA, 5 mm of slice width for 20 seconds when the patient was directed to breath rapidly or slowly. In 19 cases, which underwent both T-DRS and bronchoscopy, could evaluate the results. Only one case was overestimated by T-DRS than bronchoscopic findings, while 9 cases were underestimated and 9 cases were equal. Though T-DRS tended to underestimate the degree of the stenosis of tracheomalacia than bronchoscopic finding. T-DRS can do more objective evaluation than bronchoscopy non-invasively and thought to be useful for the evaluation of tracheomalalcia. (author)

Rarefied gas dynamics - Vol. 2

International Nuclear Information System (INIS)

Belotserkovskii, O.M.; Kogan, M.N.; Kutateladze, S.S.; Rebrov, A.K.

1985-01-01

Volume 2 presents information on the following topics: analytical formulae for cross sections and rate constants of elementary processes in gases; effects of initial molecular states in high-energy scattering of molecular beams; cesium vapor jet target produced with a supersonic nozzle; electron beam diagnostics of high temperature rarefied gas flows; free jet as an object of nonequilibrium processes investigation; free jet expansion with a strong condensation effect; rotational relaxation in high temperature jets of nitrogen; laser induced fluorescence study of free jet expansions; homogeneous condensation of nitrogen in transonic flow; the microscopic theory of clustering and nucleation; diagnostics of clusters in molecular beams; experimental studies of water-aerosol explosive vaporization; laser probing of cluster formations and dissociation in molecular beams; free molecule drag on helium clusters; kinetic model of gas suspension; molecular diffusion through a fine-pored filter versus resonate IR-radiation intensity; and rarefied gas dynamics as related to controlled thermonuclear fusion

Free Piston Problem for Isentropic Gas Dynamics

OpenAIRE

Takeno, Shigeharu

1995-01-01

We consider the existence of the generalized solution for a free piston problem for isentropic gas dynamics. By the compensated compactness theory, we can show that an approximate solution converges to a generalized solution.

Gas dynamics in strong centrifugal fields

Energy Technology Data Exchange (ETDEWEB)

Bogovalov, S.V.; Kislov, V.A.; Tronin, I.V. [National research nuclear university “MEPhI”, Kashirskoje shosse, 31,115409, Moscow (Russian Federation)

2015-03-10

Dynamics of waves generated by scopes in gas centrifuges (GC) for isotope separation is considered. The centrifugal acceleration in the GC reaches values of the order of 106g. The centrifugal and Coriolis forces modify essentially the conventional sound waves. Three families of the waves with different polarisation and dispersion exist in these conditions. Dynamics of the flow in the model GC Iguasu is investigated numerically. Comparison of the results of the numerical modelling of the wave dynamics with the analytical predictions is performed. New phenomena of the resonances in the GC is found. The resonances occur for the waves polarized along the rotational axis having the smallest dumping due to the viscosity.

Impact of gas emboli and hyperbaric treatment on respiratory function of loggerhead sea turtles (Caretta caretta).

Science.gov (United States)

Portugues, Cyril; Crespo-Picazo, Jose Luis; García-Párraga, Daniel; Altimiras, Jordi; Lorenzo, Teresa; Borque-Espinosa, Alicia; Fahlman, Andreas

2018-01-01

Fisheries interactions are the most serious threats for sea turtle populations. Despite the existence of some rescue centres providing post-traumatic care and rehabilitation, adequate treatment is hampered by the lack of understanding of the problems incurred while turtles remain entrapped in fishing gears. Recently it was shown that bycaught loggerhead sea turtles ( Caretta caretta ) could experience formation of gas emboli (GE) and develop decompression sickness (DCS) after trawl and gillnet interaction. This condition could be reversed by hyperbaric O 2 treatment (HBOT). The goal of this study was to assess how GE alters respiratory function in bycaught turtles before recompression therapy and measure the improvement after this treatment. Specifically, we assessed the effect of DCS on breath duration, expiratory and inspiratory flow and tidal volume ( V T ), and the effectiveness of HBOT to improve these parameters. HBOT significantly increased respiratory flows by 32-45% while V T increased by 33-35% immediately after HBOT. Repeated lung function testing indicated a temporal increase in both respiratory flow and V T for all bycaught turtles, but the changes were smaller than those seen immediately following HBOT. The current study suggests that respiratory function is significantly compromised in bycaught turtles with GE and that HBOT effectively restores lung function. Lung function testing may provide a novel means to help diagnose the presence of GE, be used to assess treatment efficacy, and contribute to sea turtle conservation efforts.

Interaction between gas cooking and GSTM1 null genotype in bronchial responsiveness: results from the European Community Respiratory Health Survey

Science.gov (United States)

Amaral, André F S; Ramasamy, Adaikalavan; Castro-Giner, Francesc; Minelli, Cosetta; Accordini, Simone; Sørheim, Inga-Cecilie; Pin, Isabelle; Kogevinas, Manolis; Jõgi, Rain; Balding, David J; Norbäck, Dan; Verlato, Giuseppe; Olivieri, Mario; Probst-Hensch, Nicole; Janson, Christer; Zock, Jan-Paul; Heinrich, Joachim; Jarvis, Deborah L

2014-01-01

Background Increased bronchial responsiveness is characteristic of asthma. Gas cooking, which is a major indoor source of the highly oxidant nitrogen dioxide, has been associated with respiratory symptoms and reduced lung function. However, little is known about the effect of gas cooking on bronchial responsiveness and on how this relationship may be modified by variants in the genes GSTM1, GSTT1 and GSTP1, which influence antioxidant defences. Methods The study was performed in subjects with forced expiratory volume in one second at least 70% of predicted who took part in the multicentre European Community Respiratory Health Survey, had bronchial responsiveness assessed by methacholine challenge and had been genotyped for GSTM1, GSTT1 and GSTP1-rs1695. Information on the use of gas for cooking was obtained from interviewer-led questionnaires. Effect modification by genotype on the association between the use of gas for cooking and bronchial responsiveness was assessed within each participating country, and estimates combined using meta-analysis. Results Overall, gas cooking, as compared with cooking with electricity, was not associated with bronchial responsiveness (β=−0.08, 95% CI −0.40 to 0.25, p=0.648). However, GSTM1 significantly modified this effect (β for interaction=−0.75, 95% CI −1.16 to −0.33, p=4×10−4), with GSTM1 null subjects showing more responsiveness if they cooked with gas. No effect modification by GSTT1 or GSTP1-rs1695 genotypes was observed. Conclusions Increased bronchial responsiveness was associated with gas cooking among subjects with the GSTM1 null genotype. This may reflect the oxidant effects on the bronchi of exposure to nitrogen dioxide. PMID:24613990

Real-time prediction of respiratory motion based on a local dynamic model in an augmented space.

Science.gov (United States)

Hong, S-M; Jung, B-H; Ruan, D

2011-03-21

Motion-adaptive radiotherapy aims to deliver ablative radiation dose to the tumor target with minimal normal tissue exposure, by accounting for real-time target movement. In practice, prediction is usually necessary to compensate for system latency induced by measurement, communication and control. This work focuses on predicting respiratory motion, which is most dominant for thoracic and abdominal tumors. We develop and investigate the use of a local dynamic model in an augmented space, motivated by the observation that respiratory movement exhibits a locally circular pattern in a plane augmented with a delayed axis. By including the angular velocity as part of the system state, the proposed dynamic model effectively captures the natural evolution of respiratory motion. The first-order extended Kalman filter is used to propagate and update the state estimate. The target location is predicted by evaluating the local dynamic model equations at the required prediction length. This method is complementary to existing work in that (1) the local circular motion model characterizes 'turning', overcoming the limitation of linear motion models; (2) it uses a natural state representation including the local angular velocity and updates the state estimate systematically, offering explicit physical interpretations; (3) it relies on a parametric model and is much less data-satiate than the typical adaptive semiparametric or nonparametric method. We tested the performance of the proposed method with ten RPM traces, using the normalized root mean squared difference between the predicted value and the retrospective observation as the error metric. Its performance was compared with predictors based on the linear model, the interacting multiple linear models and the kernel density estimator for various combinations of prediction lengths and observation rates. The local dynamic model based approach provides the best performance for short to medium prediction lengths under relatively

Fluid dynamic computations of the flue-gas channel in an evaporative gas turbine

Energy Technology Data Exchange (ETDEWEB)

Engdar, Ulf

1999-12-01

A new pilot power plant, based on an advanced thermodynamic cycle, called Evaporative Gas Turbine (EvGT), has been erected at the department for Heat- and Power Engineering, Lund University. The pilot plant is a part of the Evaporative Gas Turbine project, a cooperation between universities and industry in Sweden. The fluid dynamics layout of the plant is not optimized and hence no pressure drop reduction modifications have been made on the plant. A pressure drop will decrease the efficiency of the plant. Temperature measurements have shown that there maybe is a temperature stratification of the flow on the flue-gas side downstream the recuperator. A temperature stratification will influence the measurements and heat exchangers. The objective of this thesis is to investigate pressure drops and temperature stratification in the flue-gas channel between the recuperator and the economizer at the present pilot plant. Further, suggest modifications that can reduce pressure drops and/or a temperature stratification of the flow. The way of dealing with these problems was to utilize computational fluid dynamics (CFD), which makes it possible to compute the flue-gas channel in detail. The CFD-computations were conducted with a commercial computer program, called Star-CD. The pressure drop was calculated as the sum of the static- and the dynamic- pressure drop. No information about the shape of the temperature stratification was available to investigate whether a stratification will sustain or vanish. Therefore, two different temperature profiles was applied at the outlet of the recuperator. To compare modifications with the present plant, concerning the temperature stratification, a temperature rms-value was utilized as a measure of the deviation from a flow with constant temperature over a cross-section. The computations show that the pressure drop in the flue-gas channel is small compared to the pressure drop over the recuperator. Therefore, no pressure drop reducing

Dynamics of the world gas trade

International Nuclear Information System (INIS)

Chabrelie, M.F.

2004-01-01

The increasing distances between gas producing and gas consuming areas have led to foresee a considerable development of the international exchanges with a rate of about 3.5% per year up to 2020. The fluxes should represent about 32% of the commercialized production. The maritime transport by methane tanker ship will be certainly the winner of this dynamics, allowing, thanks to its flexibility, to adjust the offer to the demand of a more and more global market. This is today the bet of an industry which, motivated by technological improvements and markets potentialities, invests massively in new infrastructures. (J.S.)

SU-E-J-190: Development of Abdominal Compression & Respiratory Guiding System Using Gas Pressure Sensor

International Nuclear Information System (INIS)

Kim, T; Kim, D; Kang, S; Cho, M; Kim, K; Shin, D; Suh, T; Kim, S

2015-01-01

Purpose: Abdominal compression is known to be effective but, often makes external-marker-based monitoring of breathing motion not feasible. In this study, we developed and evaluated a system that enables both abdominal compression and monitoring of residual abdominal motion simultaneously. The system can also provide visual-biofeedback capability. Methods: The system developed consists of a compression belt, an abdominal motion monitoring sensor (gas pressure sensor) and a visual biofeedback device. The compression belt was designed to be able to compress the frontal side of the abdomen. The pressure level of the belt is controlled by air volume and monitored in real time using the gas pressure sensor. The system displays not only the real-time monitoring curve but also a guiding respiration model (e.g., a breath hold or shallow breathing curve) simultaneously on the head mounted display to help patients keep their breathing pattern as consistent as possible. Three healthy volunteers were enrolled in this pilot study and respiratory signals (pressure variations) were obtained both with and without effective abdominal compression to investigate the feasibility of the developed system. Two guidance patterns, breath hold and shallow breathing, were tested. Results: All volunteers showed smaller abdominal motion with compression (about 40% amplitude reduction compared to without compression). However, the system was able to monitor residual abdominal motion for all volunteers. Even under abdominal compression, in addition, it was possible to make the subjects successfully follow the guide patterns using the visual biofeedback system. Conclusion: The developed abdominal compression & respiratory guiding system was feasible for residual abdominal motion management. It is considered that the system can be used for a respiratory motion involved radiation therapy while maintaining the merit of abdominal compression. This work was supported by the Radiation Technology R

SU-E-J-190: Development of Abdominal Compression & Respiratory Guiding System Using Gas Pressure Sensor

Energy Technology Data Exchange (ETDEWEB)

Kim, T; Kim, D; Kang, S; Cho, M; Kim, K; Shin, D; Suh, T [The Catholic University of Korea College of Medicine, Seoul (Korea, Republic of); Kim, S [Virginia Commonwealth University, Richmond, VA (United States)

2015-06-15

Purpose: Abdominal compression is known to be effective but, often makes external-marker-based monitoring of breathing motion not feasible. In this study, we developed and evaluated a system that enables both abdominal compression and monitoring of residual abdominal motion simultaneously. The system can also provide visual-biofeedback capability. Methods: The system developed consists of a compression belt, an abdominal motion monitoring sensor (gas pressure sensor) and a visual biofeedback device. The compression belt was designed to be able to compress the frontal side of the abdomen. The pressure level of the belt is controlled by air volume and monitored in real time using the gas pressure sensor. The system displays not only the real-time monitoring curve but also a guiding respiration model (e.g., a breath hold or shallow breathing curve) simultaneously on the head mounted display to help patients keep their breathing pattern as consistent as possible. Three healthy volunteers were enrolled in this pilot study and respiratory signals (pressure variations) were obtained both with and without effective abdominal compression to investigate the feasibility of the developed system. Two guidance patterns, breath hold and shallow breathing, were tested. Results: All volunteers showed smaller abdominal motion with compression (about 40% amplitude reduction compared to without compression). However, the system was able to monitor residual abdominal motion for all volunteers. Even under abdominal compression, in addition, it was possible to make the subjects successfully follow the guide patterns using the visual biofeedback system. Conclusion: The developed abdominal compression & respiratory guiding system was feasible for residual abdominal motion management. It is considered that the system can be used for a respiratory motion involved radiation therapy while maintaining the merit of abdominal compression. This work was supported by the Radiation Technology R

History of mechanical ventilation may affect respiratory mechanics evolution in acute respiratory distress syndrome.

Science.gov (United States)

Koutsoukou, Antonia; Perraki, Helen; Orfanos, Stylianos E; Koulouris, Nikolaos G; Tromaropoulos, Andreas; Sotiropoulou, Christina; Roussos, Charis

2009-12-01

The aim of this study was to investigate the effect of mechanical ventilation (MV) before acute respiratory distress syndrome (ARDS) on subsequent evolution of respiratory mechanics and blood gases in protectively ventilated patients with ARDS. Nineteen patients with ARDS were stratified into 2 groups according to ARDS onset relative to the onset of MV: In group A (n = 11), MV was applied at the onset of ARDS; in group B (n = 8), MV had been initiated before ARDS. Respiratory mechanics and arterial blood gas were assessed in early (protectively ventilated patients with ARDS, late alteration of respiratory mechanics occurs more commonly in patients who have been ventilated before ARDS onset, suggesting that the history of MV affects the subsequent progress of ARDS even when using protective ventilation.

The dynamics of carbon dioxide equilibration after alterations in the respiratory rate

International Nuclear Information System (INIS)

Buehler, Sarah; Jensen, Marie C; Gottlieb, Dominik; Eckle, Daniel; Szczyrba, Marc; Schumann, Stefan; Guttmann, Josef; Lozano-Zahonero, Sara; Moeller, Knut

2013-01-01

Manual or automated control of mechanical ventilation can be realized as an open or closed-loop system for which the regulation of the ventilation parameters ideally is tuned to the dynamics and equilibration time of the biological system. We investigated the dynamic, transient state and equilibration time (t eq ) of the CO 2 partial pressure (PCO 2 ) after changes in the respiratory rate (ΔRR). In 17 anaesthetized patients without known history of lung disease, respiratory rate was alternately increased and decreased and end-tidal CO 2 partial pressures (PetCO 2 ) were measured. Linear relations were found between ΔRR and PetCO 2 changes (ΔPetCO 2 = 0.3 − 1.1 · ΔRR) and between ΔRR and t eq for increasing and decreasing RR (t eq(hypervent) = 0.5 · |ΔRR|, t eq(hypovent) = 0.7 · |ΔRR|). Extrapolation of the transition between two PCO 2 steady-states allowed for the prediction of the new PCO 2 steady-state as early as 0.5 · t eq with an error <4 mmHg. At bedside or in automated ventilation systems, the linear dependencies between ΔRR and ΔPCO 2 and between ΔRR and t eq as well as early steady-state prediction of PCO 2 could be used as a guidance towards a timing and step size regulation of RR that is well adapted to the biological system. (paper)

Evaluation of a respiratory assist catheter that uses an impeller within a hollow fiber membrane bundle.

Science.gov (United States)

Mihelc, Kevin M; Frankowski, Brian J; Lieber, Samuel C; Moore, Nathan D; Hattler, Brack G; Federspiel, William J

2009-01-01

Respiratory assist using an intravenous catheter may be a potential treatment for patients suffering from acute or acute-on-chronic lung failure. The objective of this study was to evaluate a novel respiratory catheter that uses an impeller within the fiber bundle to enhance gas exchange efficiency, thus requiring a smaller fiber bundle and insertional size (25 Fr) and permitting simple percutaneous insertion. Bench testing of gas exchange in deionized water was used to evaluate eight impeller designs. The three best performing impeller designs were evaluated in acute studies in four calves (122 + or - 10 kg). Gas exchange increased significantly with increasing impeller rotation rate. The degree of enhancement varied with impeller geometry. The maximum gas exchange efficiency (exchange per unit surface area) for the catheter with the best performing impeller was 529 + or - 20 ml CO(2)/min/m(2) and 513 + or - 21 ml CO(2)/min/m(2) for bench and animal studies, respectively, at a rotation rate of 20,000 rpm. Absolute CO(2) exchange was 37 and 36 ml CO(2)/min, respectively. Active mixing by rotating impellers produced 70% higher gas exchange efficiency than pulsating balloon catheters. The sensitivity of gas exchange to impeller design suggests that further improvements can be made by computational fluid dynamics-based optimization of the impeller.

Dynamics of a massive piston in an ideal gas

International Nuclear Information System (INIS)

Chernov, N I; Lebowitz, J L; Sinai, Yakov G

2002-01-01

This survey is a study of a dynamical system consisting of a massive piston in a cubic container of large size L filled with an ideal gas. The piston has mass M∼L 2 and undergoes elastic collisions with N∼L 3 non-interacting gas particles of mass m=1. It is found that under suitable initial conditions there is a scaling regime with time and space scaled by L in which the motion of the piston and the one-particle distribution of the gas satisfy autonomous coupled equations (hydrodynamic equations) such that in the limit L→∞ the mechanical trajectory of the piston converges in probability to the solution of the hydrodynamic equations for a certain period of time. There is also a heuristic discussion of the dynamics of the system on longer intervals of time

How best to capture the respiratory consequences of prematurity?

Science.gov (United States)

Ciuffini, Francesca; Robertson, Colin F; Tingay, David G

2018-03-31

Chronic respiratory morbidity is a common complication of premature birth, generally defined by the presence of bronchopulmonary dysplasia, both clinically and in trials of respiratory therapies. However, recent data have highlighted that bronchopulmonary dysplasia does not correlate with chronic respiratory morbidity in older children born preterm. Longitudinally evaluating pulmonary morbidity from early life through to childhood provides a more rational method of defining the continuum of chronic respiratory morbidity of prematurity, and offers new insights into the efficacy of neonatal respiratory interventions. The changing nature of preterm lung disease suggests that a multimodal approach using dynamic lung function assessment will be needed to assess the efficacy of a neonatal respiratory therapy and predict the long-term respiratory consequences of premature birth. Our aim is to review the literature regarding the long-term respiratory outcomes of neonatal respiratory strategies, the difficulties of assessing dynamic lung function in infants, and potential new solutions. Copyright ©ERS 2018.

Adaptive SLICE method: an enhanced method to determine nonlinear dynamic respiratory system mechanics

International Nuclear Information System (INIS)

Zhao, Zhanqi; Möller, Knut; Guttmann, Josef

2012-01-01

The objective of this paper is to introduce and evaluate the adaptive SLICE method (ASM) for continuous determination of intratidal nonlinear dynamic compliance and resistance. The tidal volume is subdivided into a series of volume intervals called slices. For each slice, one compliance and one resistance are calculated by applying a least-squares-fit method. The volume window (width) covered by each slice is determined based on the confidence interval of the parameter estimation. The method was compared to the original SLICE method and evaluated using simulation and animal data. The ASM was also challenged with separate analysis of dynamic compliance during inspiration. If the signal-to-noise ratio (SNR) in the respiratory data decreased from +∞ to 10 dB, the relative errors of compliance increased from 0.1% to 22% for the ASM and from 0.2% to 227% for the SLICE method. Fewer differences were found in resistance. When the SNR was larger than 40 dB, the ASM delivered over 40 parameter estimates (42.2 ± 1.3). When analyzing the compliance during inspiration separately, the estimates calculated with the ASM were more stable. The adaptive determination of slice bounds results in consistent and reliable parameter values. Online analysis of nonlinear respiratory mechanics will profit from such an adaptive selection of interval size. (paper)

Gas-Phase Molecular Dynamics: Theoretical Studies In Spectroscopy and Chemical Dynamics

Energy Technology Data Exchange (ETDEWEB)

Yu H. G.; Muckerman, J.T.

2012-05-29

The main goal of this program is the development and application of computational methods for studying chemical reaction dynamics and molecular spectroscopy in the gas phase. We are interested in developing rigorous quantum dynamics algorithms for small polyatomic systems and in implementing approximate approaches for complex ones. Particular focus is on the dynamics and kinetics of chemical reactions and on the rovibrational spectra of species involved in combustion processes. This research also explores the potential energy surfaces of these systems of interest using state-of-the-art quantum chemistry methods, and extends them to understand some important properties of materials in condensed phases and interstellar medium as well as in combustion environments.

MO-F-CAMPUS-J-03: Sorting 2D Dynamic MR Images Using Internal Respiratory Signal for 4D MRI

International Nuclear Information System (INIS)

Wen, Z; Hui, C; Beddar, S; Stemkens, B; Tijssen, R; Berg, C van den

2015-01-01

Purpose: To develop a novel algorithm to extract internal respiratory signal (IRS) for sorting dynamic magnetic resonance (MR) images in order to achieve four-dimensional (4D) MR imaging. Methods: Dynamic MR images were obtained with the balanced steady state free precession by acquiring each two-dimensional sagittal slice repeatedly for more than one breathing cycle. To generate a robust IRS, we used 5 different representative internal respiratory surrogates in both the image space (body area) and the Fourier space (the first two low-frequency phase components in the anterior-posterior direction, and the first two low-frequency phase components in the superior-inferior direction). A clustering algorithm was then used to search for a group of similar individual internal signals, which was then used to formulate the final IRS. A phantom study and a volunteer study were performed to demonstrate the effectiveness of this algorithm. The IRS was compared to the signal from the respiratory bellows. Results: The IRS computed by our algorithm matched well with the bellows signal in both the phantom and the volunteer studies. On average, the normalized cross correlation between the IRS and the bellows signal was 0.97 in the phantom study and 0.87 in the volunteer study, respectively. The average difference between the end inspiration times in the IRS and bellows signal was 0.18 s in the phantom study and 0.14 s in the volunteer study, respectively. 4D images sorted based on the IRS showed minimal mismatched artifacts, and the motion of the anatomy was coherent with the respiratory phases. Conclusion: A novel algorithm was developed to generate IRS from dynamic MR images to achieve 4D MR imaging. The performance of the IRS was comparable to that of the bellows signal. It can be easily implemented into the clinic and potentially could replace the use of external respiratory surrogates. This research was partially funded by the the Center for Radiation Oncology Research from

Dynamics of gas in a rotating galaxy

International Nuclear Information System (INIS)

Mulder, W.A.

1985-01-01

This thesis contains a series of papers that deal with some aspects of the gas-dynamics in a disk galaxy. The dissertation is divided in three parts. In the first part, the three dimensional response to the rotating barred potential is studied. Here, the strongest simplication is made: the pressure is neglected. This turns the problem from a global into a local one and leaves the equations of motion for a star or test particle. What if the pressure term is included. It turned out that no efficient numerical methods for computing steady gas flows with strong shocks were available. The key assumption of the second part of this thesis is the existence of a stationary solution. In that case, significant short-cuts over time-dependent integration schemes must be attainable. The various steps that lead to an efficient numerical method are described. In the third part of this dissertation, a two-dimensional code was developed. Technical aspects of the computer program are described as well as the properties of the computed quasi-steady solution. An initial global gas dynamical model for our Galaxy is constructed from one of the solutions. Here the main problem is the determination of the position of the sun in the model. (Auth.)

The origin of the hot metal-poor gas in NGC 1291 - Testing the hypothesis of gas dynamics as the cause of the gas heating

NARCIS (Netherlands)

Perez, [No Value; Freeman, K

In this paper we test the idea that the low-metallicity hot gas in the centre of NGC 1291 is heated via a dynamical process. In this scenario, the gas from the outer gas-rich ring loses energy through bar-driven shocks and falls to the centre. Heating of the gas to X-ray temperatures comes from the

Dynamic safety assessment of natural gas stations using Bayesian network

Energy Technology Data Exchange (ETDEWEB)

Zarei, Esmaeil, E-mail: smlzarei65@gmail.com [Center of Excellence for Occupational Health Engineering, Research Center for Health Sciences, Faculty of Health, Hamadan University of Medical Sciences, Hamadan (Iran, Islamic Republic of); Azadeh, Ali [School of Industrial and Systems Engineering, Center of Excellence for Intelligent-Based Experimental Mechanic, College of Engineering, University of Tehran (Iran, Islamic Republic of); Khakzad, Nima [Safety and Security Science Section, Delft University of Technology, Delft (Netherlands); Aliabadi, Mostafa Mirzaei [Center of Excellence for Occupational Health Engineering, Research Center for Health Sciences, Faculty of Health, Hamadan University of Medical Sciences, Hamadan (Iran, Islamic Republic of); Mohammadfam, Iraj, E-mail: mohammadfam@umsha.ac.ir [Center of Excellence for Occupational Health Engineering, Research Center for Health Sciences, Faculty of Health, Hamadan University of Medical Sciences, Hamadan (Iran, Islamic Republic of)

2017-01-05

Graphical abstract: Dynamic cause-consequence analysis of the regulator system failure using BN. - Highlights: • A dynamic and comprehensive QRA (DCQRA) framework is proposed for safety assessment of CGSs. • Bow-tie diagram and Bayesian network are employed for accident scenario modeling. • Critical basic events and minimal cut sets are identified using probability updating. - Abstract: Pipelines are one of the most popular and effective ways of transporting hazardous materials, especially natural gas. However, the rapid development of gas pipelines and stations in urban areas has introduced a serious threat to public safety and assets. Although different methods have been developed for risk analysis of gas transportation systems, a comprehensive methodology for risk analysis is still lacking, especially in natural gas stations. The present work is aimed at developing a dynamic and comprehensive quantitative risk analysis (DCQRA) approach for accident scenario and risk modeling of natural gas stations. In this approach, a FMEA is used for hazard analysis while a Bow-tie diagram and Bayesian network are employed to model the worst-case accident scenario and to assess the risks. The results have indicated that the failure of the regulator system was the worst-case accident scenario with the human error as the most contributing factor. Thus, in risk management plan of natural gas stations, priority should be given to the most probable root events and main contribution factors, which have identified in the present study, in order to reduce the occurrence probability of the accident scenarios and thus alleviate the risks.

Dynamic safety assessment of natural gas stations using Bayesian network

International Nuclear Information System (INIS)

Zarei, Esmaeil; Azadeh, Ali; Khakzad, Nima; Aliabadi, Mostafa Mirzaei; Mohammadfam, Iraj

2017-01-01

Graphical abstract: Dynamic cause-consequence analysis of the regulator system failure using BN. - Highlights: • A dynamic and comprehensive QRA (DCQRA) framework is proposed for safety assessment of CGSs. • Bow-tie diagram and Bayesian network are employed for accident scenario modeling. • Critical basic events and minimal cut sets are identified using probability updating. - Abstract: Pipelines are one of the most popular and effective ways of transporting hazardous materials, especially natural gas. However, the rapid development of gas pipelines and stations in urban areas has introduced a serious threat to public safety and assets. Although different methods have been developed for risk analysis of gas transportation systems, a comprehensive methodology for risk analysis is still lacking, especially in natural gas stations. The present work is aimed at developing a dynamic and comprehensive quantitative risk analysis (DCQRA) approach for accident scenario and risk modeling of natural gas stations. In this approach, a FMEA is used for hazard analysis while a Bow-tie diagram and Bayesian network are employed to model the worst-case accident scenario and to assess the risks. The results have indicated that the failure of the regulator system was the worst-case accident scenario with the human error as the most contributing factor. Thus, in risk management plan of natural gas stations, priority should be given to the most probable root events and main contribution factors, which have identified in the present study, in order to reduce the occurrence probability of the accident scenarios and thus alleviate the risks.

Emergent dynamic structures and statistical law in spherical lattice gas automata

Science.gov (United States)

Yao, Zhenwei

2017-12-01

Various lattice gas automata have been proposed in the past decades to simulate physics and address a host of problems on collective dynamics arising in diverse fields. In this work, we employ the lattice gas model defined on the sphere to investigate the curvature-driven dynamic structures and analyze the statistical behaviors in equilibrium. Under the simple propagation and collision rules, we show that the uniform collective movement of the particles on the sphere is geometrically frustrated, leading to several nonequilibrium dynamic structures not found in the planar lattice, such as the emergent bubble and vortex structures. With the accumulation of the collision effect, the system ultimately reaches equilibrium in the sense that the distribution of the coarse-grained speed approaches the two-dimensional Maxwell-Boltzmann distribution despite the population fluctuations in the coarse-grained cells. The emergent regularity in the statistical behavior of the system is rationalized by mapping our system to a generalized random walk model. This work demonstrates the capability of the spherical lattice gas automaton in revealing the lattice-guided dynamic structures and simulating the equilibrium physics. It suggests the promising possibility of using lattice gas automata defined on various curved surfaces to explore geometrically driven nonequilibrium physics.

Emergent dynamic structures and statistical law in spherical lattice gas automata.

Science.gov (United States)

Yao, Zhenwei

2017-12-01

Various lattice gas automata have been proposed in the past decades to simulate physics and address a host of problems on collective dynamics arising in diverse fields. In this work, we employ the lattice gas model defined on the sphere to investigate the curvature-driven dynamic structures and analyze the statistical behaviors in equilibrium. Under the simple propagation and collision rules, we show that the uniform collective movement of the particles on the sphere is geometrically frustrated, leading to several nonequilibrium dynamic structures not found in the planar lattice, such as the emergent bubble and vortex structures. With the accumulation of the collision effect, the system ultimately reaches equilibrium in the sense that the distribution of the coarse-grained speed approaches the two-dimensional Maxwell-Boltzmann distribution despite the population fluctuations in the coarse-grained cells. The emergent regularity in the statistical behavior of the system is rationalized by mapping our system to a generalized random walk model. This work demonstrates the capability of the spherical lattice gas automaton in revealing the lattice-guided dynamic structures and simulating the equilibrium physics. It suggests the promising possibility of using lattice gas automata defined on various curved surfaces to explore geometrically driven nonequilibrium physics.

THE INFLUENCE OF AEROSOL GAS-DYNAMIC SUSPENSION CLEANING ON SURFACE OF THE AIRCRAFT PARTS

Directory of Open Access Journals (Sweden)

Vitaly D. Hizhko

2008-02-01

Full Text Available  The specificity of the surface microgeometry formation under the influence of aerosol gas-dynamic suspension flow was considered. The composition and character of metallic surface layer formation of aircraft parts was investigated. The possibility of surface material composition and properties adjustment changing aerosol gas-dynamic suspension flow parameters was determined. The hypothesis about the possibility of using aerosol gas-dynamic suspension flow to form corrosion-resistant coating on the detail metallic surfaces was set up.

Dynamic gating window for compensation of baseline shift in respiratory-gated radiation therapy

International Nuclear Information System (INIS)

Pepin, Eric W.; Wu Huanmei; Shirato, Hiroki

2011-01-01

Purpose: To analyze and evaluate the necessity and use of dynamic gating techniques for compensation of baseline shift during respiratory-gated radiation therapy of lung tumors. Methods: Motion tracking data from 30 lung tumors over 592 treatment fractions were analyzed for baseline shift. The finite state model (FSM) was used to identify the end-of-exhale (EOE) breathing phase throughout each treatment fraction. Using duty cycle as an evaluation metric, several methods of end-of-exhale dynamic gating were compared: An a posteriori ideal gating window, a predictive trend-line-based gating window, and a predictive weighted point-based gating window. These methods were evaluated for each of several gating window types: Superior/inferior (SI) gating, anterior/posterior beam, lateral beam, and 3D gating. Results: In the absence of dynamic gating techniques, SI gating gave a 39.6% duty cycle. The ideal SI gating window yielded a 41.5% duty cycle. The weight-based method of dynamic SI gating yielded a duty cycle of 36.2%. The trend-line-based method yielded a duty cycle of 34.0%. Conclusions: Dynamic gating was not broadly beneficial due to a breakdown of the FSM's ability to identify the EOE phase. When the EOE phase was well defined, dynamic gating showed an improvement over static-window gating.

Effects of gas periodic stimulation on key enzyme activity in gas double-dynamic solid state fermentation (GDD-SSF).

Science.gov (United States)

Chen, Hongzhang; Shao, Meixue; Li, Hongqiang

2014-03-05

The heat and mass transfer have been proved to be the important factors in air pressure pulsation for cellulase production. However, as process of enzyme secretion, the cellulase formation has not been studied in the view of microorganism metabolism and metabolic key enzyme activity under air pressure pulsation condition. Two fermentation methods in ATPase activity, cellulase productivity, weight lose rate and membrane permeability were systematically compared. Results indicated that gas double-dynamic solid state fermentation had no obviously effect on cell membrane permeability. However, the relation between ATPase activity and weight loss rate was linearly dependent with r=0.9784. Meanwhile, the results also implied that gas periodic stimulation had apparently strengthened microbial metabolism through increasing ATPase activity during gas double-dynamic solid state fermentation, resulting in motivating the production of cellulase by Trichoderma reesei YG3. Therefore, the increase of ATPase activity would be another crucial factor to strengthen fermentation process for cellulase production under gas double-dynamic solid state fermentation. Copyright © 2013 Elsevier Inc. All rights reserved.

Observation of Dynamical Super-Efimovian Expansion in a Unitary Fermi Gas

Science.gov (United States)

Deng, Shujin; Diao, Pengpeng; Li, Fang; Yu, Qianli; Yu, Shi; Wu, Haibin

2018-03-01

We report an observation of a dynamical super Efimovian expansion in a strongly interacting Fermi gas by engineering time dependent external harmonic trap frequencies. When the trap frequency is tailored as [1 /4 t2+1 /t2λ log2(t /t*)]1/2, where t* and λ are two controllable parameters, and the change is faster than a critical value, the expansion of such a quantum gas shows novel dynamics that share the same characteristics as the super Efimov effect. A clear double-log periodicity with discrete geometric scaling emerges for the cloud size in the expansion. The universality of such scaling dynamics is verified both in the noninteracting and in the unitarity limit of Fermi gas. Moreover, the measured energy scaling reveals that the potential and internal energy also show double-log periodicity with a π /2 phase difference, but the total energy is monotonically decreased. Observing super Efimovian evolution represents a paradigm in probing universal properties and allows us in a new way to study many-body nonequilibrium dynamics with experiments.

The effect of respiratory cycle and radiation beam-on timing on the dose distribution of free-breathing breast treatment using dynamic IMRT

International Nuclear Information System (INIS)

Ding Chuxiong; Li Xiang; Huq, M. Saiful; Saw, Cheng B.; Heron, Dwight E.; Yue, Ning J.

2007-01-01

In breast cancer treatment, intensity-modulated radiation therapy (IMRT) can be utilized to deliver more homogeneous dose to target tissues to minimize the cosmetic impact. We have investigated the effect of the respiratory cycle and radiation beam-on timing on the dose distribution in free-breathing dynamic breast IMRT treatment. Six patients with early stage cancer of the left breast were included in this study. A helical computed tomography (CT) scan was acquired for treatment planning. A four-dimensional computed tomography (4D CT) scan was obtained right after the helical CT scan with little or no setup uncertainty to simulate patient respiratory motion. After optimizing based on the helical CT scan, the sliding-window dynamic multileaf collimator (DMLC) leaf sequence was segmented into multiple sections that corresponded to various respiratory phases per respiratory cycle and radiation beam-on timing. The segmented DMLC leaf sections were grouped according to respiratory phases and superimposed over the radiation fields of corresponding 4D CT image set. Dose calculation was then performed for each phase of the 4D CT scan. The total dose distribution was computed by accumulating the contribution of dose from each phase to every voxel in the region of interest. This was tracked by a deformable registration program throughout all of the respiratory phases of the 4D CT scan. A dose heterogeneity index, defined as the ratio between (D 20 -D 80 ) and the prescription dose, was introduced to numerically illustrate the impact of respiratory motion on the dose distribution of treatment volume. A respiratory cycle range of 4-8 s and randomly distributed beam-on timing were assigned to simulate the patient respiratory motion during the free-breathing treatment. The results showed that the respiratory cycle period and radiation beam-on timing presented limited impact on the target dose coverage and slightly increased the target dose heterogeneity. This motion impact

Comparison of 133Xe gas dynamic SPECT and thin-section CT in patients with pulmonary emphysema

International Nuclear Information System (INIS)

Takahashi, Kazue; Satoh, Katashi; Ohkawa, Motoomi

2001-01-01

We assessed 133 Xe gas dynamic single photon emission computed tomography (SPECT) by comparing washout axial images with thin-section CT (TSCT) in patients with pulmonary emphysema. Twenty-three patients were studied. All patients were diagnosed as having pulmonary emphysema on the basis of TSCT. We compared TSCT of upper, middle and lower lung fields with 133 Xe gas dynamic SPECT axial images at the corresponding levels during the 3 to 4 minutes of washout phase. If the degree of 133 Xe gas retention or TSCT finding of ventral and dorsal parts was not the same, the images were divided into two parts. A total of 174 lesions in 23 cases were examined, but 3 lesions having no retention of 133 Xe gas at equilibrium phase were excluded. The results showed that: there were 37 lesions (21.6%) with equivalent severity on both images; there were 42 lesions (24.5%) with more severity on 133 Xe gas dynamic SPECT than on TSCT; and there were 92 lesions (53.8%) with more severity on TSCT than on 133 Xe gas dynamic SPECT. The severity on 133 Xe gas dynamic SPECT and TSCT was not always compatible. One of the reasons for the variable 133 Xe gas retention even when the lesion had the same severity on TSCT, may be bronchial stricture which cannot be seen on TSCT. By comparison of axial images of 133 Xe gas dynamic SPECT with CT images, we could recognize the areas of 133 Xe gas retention in detail. Results suggest that 133 Xe gas dynamic SPECT can be useful to identify ventilation impairment in pulmonary emphysema. (author)

The real gas dynamics of the fluids of high specific heat

International Nuclear Information System (INIS)

Meier, G.E.A.

1987-01-01

The gas dynamics of real fluids show several new effects beyond the gas dynamics of ideal substances. Many of these effects rely on phase changes in the flow fields and can be explained with the help of more complicated thermal and caloric state equations of the real fluids. Complete adiabatic liquefaction and evaporation are possible for those substances whose specific heat exceeds a limit of about twenty gas constants. These fluids consisting of great molecules have so much internal energy storage capacity in their numerous vibrational degrees of freedom that the heat of evaporation can be supplied or also stored in the case of condensation. So liquefaction shock waves, which transform a gas completely or partly into a liquid, are possible. The shock front becomes thereby the surface of a liquid. Partial liquefaction with droplet condensation occurs in weaker shock waves. On the other hand a superheated liquid with high specific heat can be changed into a gas or mixture state in expansion waves or flows. (orig.)

Incremental exercise test performance with and without a respiratory ...

African Journals Online (AJOL)

Incremental exercise test performance with and without a respiratory gas collection system. ... PROMOTING ACCESS TO AFRICAN RESEARCH ... Industrial- type mask wear is thought to impair exercise performance through increased respiratory dead space, flow ... EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT

[Smartphone application for blood gas interpretation].

Science.gov (United States)

Obiols, Julien; Bardo, Pascale; Garnier, Jean-Pierre; Brouard, Benoît

2013-01-01

Ninety four per cent of health professionals use their smartphone for business purposes and more than 50% has medical applications. The «Blood Gas» application was created to be part of this dynamic and participate to e-health development in France. The «Blood Gas» application facilitates interpretation of the results of blood gas analysis using an algorithm developed with reference to a medical bibliography. It can detect some complex or intricate acid-base disorders in evaluating the effectiveness of the secondary response. The application also studied the respiratory status of the patient by calculating the PaO2/FiO2 ratio and the alveol-arterial gradient. It also indicates the presence of a shunt effect. Finally, a specific module to calculate the SID (strong ion difference) depending on the model of Stewart can detect complex acid-base disorders.

A compartment model of alveolar-capillary oxygen diffusion with ventilation-perfusion gradient and dynamics of air transport through the respiratory tract.

Science.gov (United States)

Jaworski, Jacek; Redlarski, Grzegorz

2014-08-01

This paper presents a model of alveolar-capillary oxygen diffusion with dynamics of air transport through the respiratory tract. For this purpose electrical model representing the respiratory tract mechanics and differential equations representing oxygen membrane diffusion are combined. Relevant thermodynamic relations describing the mass of oxygen transported into the human body are proposed as the connection between these models, as well as the influence of ventilation-perfusion mismatch on the oxygen diffusion. The model is verified based on simulation results of varying exercise intensities and statistical calculations of the results obtained during various clinical trials. The benefit of the approach proposed is its application in simulation-based research aimed to generate quantitative data of normal and pathological conditions. Based on the model presented, taking into account many essential physiological processes and air transport dynamics, comprehensive and combined studies of the respiratory efficiency can be performed. The impact of physical exercise, precise changes in respiratory tract mechanics and alterations in breathing pattern can be analyzed together with the impact of various changes in alveolar-capillary oxygen diffusion. This may be useful in simulation of effects of many severe medical conditions and increased activity level. Copyright © 2014 Elsevier Ltd. All rights reserved.

Assessment of blood gas parameters and the degree of inflammation in noninvasive positive pressure ventilation combined with aminophylline treatment of COPD complicated with type II respiratory failure

Directory of Open Access Journals (Sweden)

Jin-Ru Zhang

2016-10-01

Full Text Available Objective: To analyze the effect of noninvasive positive pressure ventilation combined with aminophylline therapy on blood gas parameters and the degree of inflammation in patients with COPD and type II respiratory failure. Methods: A total of 80 patients with COPD and type Ⅱ respiratory failure were randomly divided into observation group and control group (n=40, control group received symptomatic treatment + aminophylline treatment, observation group received symptomatic treatment + aminophylline + noninvasive positive pressure ventilation treatment, and then differences in blood gas parameters, pulmonary function parameters, hemorheology parameters and inflammatory factor levels were compared between two groups of patients after treatment. Results: Radial artery pH and PO2 values of observation group after treatment were higher than those of control group while PCO2, Cl- and CO2CP values were lower than those of control group; pulmonary function parameters FVC, FEV1, FEF25-75, MMF, PEF and FRC values of observation group after treatment were higher than those of control group; whole blood viscosity (150 s- and 10 s-, plasma viscosity, fibrinogen, erythrocyte aggregation index and erythrocyte rigidity index values in peripheral venous blood of observation group after treatment were lower than those of control group; serum IL-17, IL-33, TREM-1, sICAM-1 and PGE2 levels of observation group after treatment were lower than those of control group. Conclusion: Noninvasive positive pressure ventilation combined with aminophylline can optimize the respiratory function of patients with COPD and type II respiratory failure and improve blood gas parameters and the degree of inflammation.

Imaging of respiratory muscles in neuromuscular disease: A review.

Science.gov (United States)

Harlaar, L; Ciet, P; van der Ploeg, A T; Brusse, E; van der Beek, N A M E; Wielopolski, P A; de Bruijne, M; Tiddens, H A W M; van Doorn, P A

2018-03-01

Respiratory muscle weakness frequently occurs in patients with neuromuscular disease. Measuring respiratory function with standard pulmonary function tests provides information about the contribution of all respiratory muscles, the lungs and airways. Imaging potentially enables the study of different respiratory muscles, including the diaphragm, separately. In this review, we provide an overview of imaging techniques used to study respiratory muscles in neuromuscular disease. We identified 26 studies which included a total of 573 patients with neuromuscular disease. Imaging of respiratory muscles was divided into static and dynamic techniques. Static techniques comprise chest radiography, B-mode (brightness mode) ultrasound, CT and MRI, and are used to assess the position and thickness of the diaphragm and the other respiratory muscles. Dynamic techniques include fluoroscopy, M-mode (motion mode) ultrasound and MRI, used to assess diaphragm motion in one or more directions. We discuss how these imaging techniques relate with spirometric values and whether these can be used to study the contribution of the different respiratory muscles in patients with neuromuscular disease. Copyright © 2017. Published by Elsevier B.V.

Ablation plume dynamics in a background gas

DEFF Research Database (Denmark)

Amoruso, Salvatore; Schou, Jørgen; Lunney, James G.

2010-01-01

The expansion of a plume in a background gas of pressure comparable to that used in pulsed laser deposition (PLD) has been analyzed in terms of the model of Predtechensky and Mayorov (PM). This approach gives a relatively clear and simple description of the essential hydrodynamics during the expa......The expansion of a plume in a background gas of pressure comparable to that used in pulsed laser deposition (PLD) has been analyzed in terms of the model of Predtechensky and Mayorov (PM). This approach gives a relatively clear and simple description of the essential hydrodynamics during...... the expansion. The model also leads to an insightful treatment of the stopping behavior in dimensionless units for plumes and background gases of different atomic/molecular masses. The energetics of the plume dynamics can also be treated with this model. Experimental time-of-flight data of silver ions in a neon...... background gas show a fair agreement with predictions from the PM-model. Finally we discuss the validity of the model, if the work done by the pressure of the background gas is neglected....

Lateral Dynamics of Flexible Rotors Supported by Controllable Gas Bearings Theory & Experiment

DEFF Research Database (Denmark)

Pierart Vásquez, Fabián Gonzalo; Santos, Ilmar

2015-01-01

Active gas bearings might represent a mechatronic answer to the growing industrial need for high performance turbomachinery. In this framework, the paper gives a theoretical and experimental contribution to the improvement of lateral dynamics of rotating machines. The work aims at demonstrating...... theoretically as well as experimentally the feasibility of applying active lubrication to gas journal bearings. The operation principle is to generate active forces by regulating the radial injection of a compressible lubricant (gas) by means of piezoelectric actuators mounted on the back of the bearing sleeve....... The active control principle is built using eddy-current sensor signals to detect the lateral motion of the rotor. A feedback law is used to couple the lateral dynamics of a flexible rotor-bearing system with the pneumatic and dynamic characteristics of a piezoelectric actuated valve system. A proportional...

Lattice gas simulations of dynamical geometry in two dimensions.

Science.gov (United States)

Klales, Anna; Cianci, Donato; Needell, Zachary; Meyer, David A; Love, Peter J

2010-10-01

We present a hydrodynamic lattice gas model for two-dimensional flows on curved surfaces with dynamical geometry. This model is an extension to two dimensions of the dynamical geometry lattice gas model previously studied in one dimension. We expand upon a variation of the two-dimensional flat space Frisch-Hasslacher-Pomeau (FHP) model created by Frisch [Phys. Rev. Lett. 56, 1505 (1986)] and independently by Wolfram, and modified by Boghosian [Philos. Trans. R. Soc. London, Ser. A 360, 333 (2002)]. We define a hydrodynamic lattice gas model on an arbitrary triangulation whose flat space limit is the FHP model. Rules that change the geometry are constructed using the Pachner moves, which alter the triangulation but not the topology. We present results on the growth of the number of triangles as a function of time. Simulations show that the number of triangles grows with time as t(1/3), in agreement with a mean-field prediction. We also present preliminary results on the distribution of curvature for a typical triangulation in these simulations.

Gas dynamics models for an oscillating gaseous core fission reactor

Energy Technology Data Exchange (ETDEWEB)

Kuijper, J.C.; Dam, H. van; Hoogenboom, J.E. (Interuniversitair Reactor Inst., Delft (Netherlands))

1991-01-01

Two one-dimensional models are developed for the investigation of the gas dynamical behaviour of the fuel gas in a cylindrical gaseous core fission reactor. By numerical and analytical calculations, it is shown that, for the case where a direct energy extraction mechanism (such as magneto-hydrodynamics (MHD)) is not present, increasing density oscillations occur in the gas. Also an estimate is made of the attainable direct energy conversion efficiency, for the case where a direct energy extraction mechanism is present. (author).

Exercising upper respiratory videoendoscopic evaluation of 100 nonracing performance horses with abnormal respiratory noise and/or poor performance.

Science.gov (United States)

Davidson, E J; Martin, B B; Boston, R C; Parente, E J

2011-01-01

Although well documented in racehorses, there is paucity in the literature regarding the prevalence of dynamic upper airway abnormalities in nonracing performance horses. To describe upper airway function of nonracing performance horses with abnormal respiratory noise and/or poor performance via exercising upper airway videoendoscopy. Medical records of nonracing performance horses admitted for exercising evaluation with a chief complaint of abnormal respiratory noise and/or poor performance were reviewed. All horses had video recordings of resting and exercising upper airway endoscopy. Relationships between horse demographics, resting endoscopic findings, treadmill intensity and implementation of head and neck flexion during exercise with exercising endoscopic findings were examined. Dynamic upper airway obstructions were observed in 72% of examinations. Head and neck flexion was necessary to obtain a diagnosis in 21 horses. Pharyngeal wall collapse was the most prevalent upper airway abnormality, observed in 31% of the examinations. Complex abnormalities were noted in 27% of the examinations. Resting laryngeal dysfunction was significantly associated with dynamic arytenoid collapse and the odds of detecting intermittent dorsal displacement of the soft palate (DDSP) during exercise in horses with resting DDSP was only 7.7%. Exercising endoscopic observations were different from the resting observations in 54% of examinations. Dynamic upper airway obstructions were common in nonracing performance horses with respiratory noise and/or poor performance. Resting endoscopy was only helpful in determining exercising abnormalities with recurrent laryngeal neuropathy. This study emphasises the importance of exercising endoscopic evaluation in nonracing performance horses with abnormal respiratory noise and/or poor performance for accurate assessment of dynamic upper airway function. © 2010 EVJ Ltd.

Model-based dynamic control and optimization of gas networks

Energy Technology Data Exchange (ETDEWEB)

Hofsten, Kai

2001-07-01

This work contributes to the research on control, optimization and simulation of gas transmission systems to support the dispatch personnel at gas control centres for the decision makings in the daily operation of the natural gas transportation systems. Different control and optimization strategies have been studied. The focus is on the operation of long distance natural gas transportation systems. Stationary optimization in conjunction with linear model predictive control using state space models is proposed for supply security, the control of quality parameters and minimization of transportation costs for networks offering transportation services. The result from the stationary optimization together with a reformulation of a simplified fluid flow model formulates a linear dynamic optimization model. This model is used in a finite time control and state constrained linear model predictive controller. The deviation from the control and the state reference determined from the stationary optimization is penalized quadratically. Because of the time varying status of infrastructure, the control space is also generally time varying. When the average load is expected to change considerably, a new stationary optimization is performed, giving a new state and control reference together with a new dynamic model that is used for both optimization and state estimation. Another proposed control strategy is a control and output constrained nonlinear model predictive controller for the operation of gas transmission systems. Here, the objective is also the security of the supply, quality control and minimization of transportation costs. An output vector is defined, which together with a control vector are both penalized quadratically from their respective references in the objective function. The nonlinear model predictive controller can be combined with a stationary optimization. At each sampling instant, a non convex nonlinear programming problem is solved giving a local minimum

SU-E-J-261: Statistical Analysis and Chaotic Dynamics of Respiratory Signal of Patients in BodyFix

Energy Technology Data Exchange (ETDEWEB)

Michalski, D; Huq, M; Bednarz, G; Lalonde, R; Yang, Y; Heron, D [University of Pittsburgh Medical Center, Pittsburgh, PA (United States)

2014-06-01

Purpose: To quantify respiratory signal of patients in BodyFix undergoing 4DCT scan with and without immobilization cover. Methods: 20 pairs of respiratory tracks recorded with RPM system during 4DCT scan were analyzed. Descriptive statistic was applied to selected parameters of exhale-inhale decomposition. Standardized signals were used with the delay method to build orbits in embedded space. Nonlinear behavior was tested with surrogate data. Sample entropy SE, Lempel-Ziv complexity LZC and the largest Lyapunov exponents LLE were compared. Results: Statistical tests show difference between scans for inspiration time and its variability, which is bigger for scans without cover. The same is for variability of the end of exhalation and inhalation. Other parameters fail to show the difference. For both scans respiratory signals show determinism and nonlinear stationarity. Statistical test on surrogate data reveals their nonlinearity. LLEs show signals chaotic nature and its correlation with breathing period and its embedding delay time. SE, LZC and LLE measure respiratory signal complexity. Nonlinear characteristics do not differ between scans. Conclusion: Contrary to expectation cover applied to patients in BodyFix appears to have limited effect on signal parameters. Analysis based on trajectories of delay vectors shows respiratory system nonlinear character and its sensitive dependence on initial conditions. Reproducibility of respiratory signal can be evaluated with measures of signal complexity and its predictability window. Longer respiratory period is conducive for signal reproducibility as shown by these gauges. Statistical independence of the exhale and inhale times is also supported by the magnitude of LLE. The nonlinear parameters seem more appropriate to gauge respiratory signal complexity since its deterministic chaotic nature. It contrasts with measures based on harmonic analysis that are blind for nonlinear features. Dynamics of breathing, so crucial for

SU-E-J-261: Statistical Analysis and Chaotic Dynamics of Respiratory Signal of Patients in BodyFix

International Nuclear Information System (INIS)

Michalski, D; Huq, M; Bednarz, G; Lalonde, R; Yang, Y; Heron, D

2014-01-01

Purpose: To quantify respiratory signal of patients in BodyFix undergoing 4DCT scan with and without immobilization cover. Methods: 20 pairs of respiratory tracks recorded with RPM system during 4DCT scan were analyzed. Descriptive statistic was applied to selected parameters of exhale-inhale decomposition. Standardized signals were used with the delay method to build orbits in embedded space. Nonlinear behavior was tested with surrogate data. Sample entropy SE, Lempel-Ziv complexity LZC and the largest Lyapunov exponents LLE were compared. Results: Statistical tests show difference between scans for inspiration time and its variability, which is bigger for scans without cover. The same is for variability of the end of exhalation and inhalation. Other parameters fail to show the difference. For both scans respiratory signals show determinism and nonlinear stationarity. Statistical test on surrogate data reveals their nonlinearity. LLEs show signals chaotic nature and its correlation with breathing period and its embedding delay time. SE, LZC and LLE measure respiratory signal complexity. Nonlinear characteristics do not differ between scans. Conclusion: Contrary to expectation cover applied to patients in BodyFix appears to have limited effect on signal parameters. Analysis based on trajectories of delay vectors shows respiratory system nonlinear character and its sensitive dependence on initial conditions. Reproducibility of respiratory signal can be evaluated with measures of signal complexity and its predictability window. Longer respiratory period is conducive for signal reproducibility as shown by these gauges. Statistical independence of the exhale and inhale times is also supported by the magnitude of LLE. The nonlinear parameters seem more appropriate to gauge respiratory signal complexity since its deterministic chaotic nature. It contrasts with measures based on harmonic analysis that are blind for nonlinear features. Dynamics of breathing, so crucial for

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

Science.gov (United States)

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.

Respiratory Disorders in Complicated Cervical Spine Injury

Directory of Open Access Journals (Sweden)

S. A. Pervukhin

2016-01-01

Full Text Available Objective. Evaluating the results of respiratory therapy in patients with complicated traumatic injury of the cervical spine.Materials and methods. A retrospective comparative analysis of the clinical course was carried out in 52 patients with complicated traumatic injury of the cervical spine: group A: complete spinal cord injury (ASIA A, 37 patients and group B: incomplete injury (ASIA B, 15 patients. The severity of patients' status on integral scales, parameters of the respiratory pattern and thoracopulmonary compliance, gas composition, and acidbase status of the blood were assessed. Data on patients who required prolonged mechanical ventilation, duration of mechanical ventilation, incidence of nosocomial pneumonia, duration of stay in the ICU, time of hospital treatment, and mortality were included in the analysis. Results. The average APACHE II and SOFA scores were higher in group A patients. The development of the acute respiratory failure required longterm mechanical ventilation (more than 48 hours in 91.4% of group A patients and in 53.3% of group B patients. Ventilatorassociated pneumonia complicated the disease in 81.3% of group A patients and 62.5% of group B patients and was accompanied by sepsis in 25% and 12.5% of cases, respectively. Statistically significant deterioration of biomechanical properties and gas exchange function of the lungs was observed in patients complicated with septic pneumonia.Conclusion. Patients with complicated ASIA A and ASIA B cervical spine injuries demonstrate the presence of respiratory failure of neurogenic origin. In addition, the infectious bronchopulmonary complications aggravated respiratory failure in patients with ASIA A injury in 70.3% versus 33.3% in patients with ASIA B. Developmentof pulmonogenic sepsis led to deterioration of the biomechanical and gas exchange functions of the lungs and increased the likelihood of unfavorable outcome of the disease in 77.8% of cases. The high

A brain-targeted ampakine compound protects against opioid-induced respiratory depression.

Science.gov (United States)

Dai, Wei; Xiao, Dian; Gao, Xiang; Zhou, Xin-Bo; Fang, Tong-Yu; Yong, Zheng; Su, Rui-Bin

2017-08-15

The use of opioid drugs for pain relief can induce life-threatening respiratory depression. Although naloxone effectively counteracts opioid-induced respiratory depression, it diminishes the efficacy of analgesia. Our studies indicate that ampakines, in particular, a brain-targeted compound XD-8-17C, are able to reverse respiratory depression without affecting analgesia at relatively low doses. Mice and rats were subcutaneously or intravenously injected with the opioid agonist TH-030418 to induce moderate or severe respiratory depression. XD-8-17C was intravenously administered before or after TH-030418. The effect of XD-8-17C on opioid-induced respiratory depression was evaluated in terms of the opioid-induced acute death rate, arterial blood gas analysis and pulmonary function tests. In addition, the hot-plate test was conducted to investigate whether XD-8-17C influenced opioid-induced analgesia. Pre-treatment with XD-8-17C significantly reduced opioid-induced acute death, and increased the median lethal dose of TH-030418 by 4.7-fold. Blood gas analysis and pulmonary function tests demonstrated that post-treatment with XD-8-17C alleviated respiratory depression, as indicated by restoration of arterial blood gas (pO 2 , sO 2 , cK + ) and lung function parameters (respiratory frequency, minute ventilation) to the normal range. The hot-plate test showed that XD-8-17C had no impact on the antinociceptive efficacy of morphine. The ability of XD-8-17C to reverse opioid-induced respiratory depression has the potential to increase the safety and convenience of opioid treatment. These findings contribute to the discovery of novel therapeutic agents that protect against opioid-induced respiratory depression without loss of analgesia. Copyright © 2017 Elsevier B.V. All rights reserved.

Modelling of gas-liquid reactors - stability and dynamic behaviour of gas-liquid mass transfer accompanied by irreversible reaction

NARCIS (Netherlands)

Elk, E.P. van; Borman, P.C.; Kuipers, J.A.M.; Versteeg, G.F.

1999-01-01

The dynamic behaviour and stability of single-phase reacting systems has been investigated thoroughly in the past and design rules for stable operation are available from literature. The dynamic behaviour of gas-liquid processes is considerably more complex and has received relatively little

Static and dynamic modelling of gas turbines in advanced cycles

Energy Technology Data Exchange (ETDEWEB)

Gustafsson, Jan-Olof

1998-12-01

Gas turbines have been in operation for at least 50 years. The engine is used for propulsion of aircraft and high speed ships. It is used for power production in remote locations and for peak load and emergency situations. Gas turbines have been used in combined cycles for 20 to 30 years. Highly efficient power plants based on gas turbines are a competitive option for the power industry today. The thermal efficiency of the simple cycle gas turbine has increased due to higher turbine inlet temperatures and improved compressor and expander designs. Equally important are the improved cycles in which the gas turbine operates. One example is the combined cycle that uses steam for turbine cooling. Steam is extracted from the bottoming cycle, then used as airfoil coolant in a closed loop and returned to the bottoming cycle. The Evaporative Gas Turbine (EvGT), also known as the Humid Air Turbine (HAT), is another advanced cycle. A mixture of air and water vapour is used as working media. Air from the compressor outlet is humidified and then preheated in a recuperator prior to combustion. The static and dynamic performance is changed when the gas turbine is introduced in an evaporative cycle. The cycle is gaining in popularity, but so far it has not been demonstrated. A Swedish joint program to develop the cycle has been in operation since 1993. As part of the program, a small pilot plant is being erected at the Lund Institute of Technology (LTH). The plant is based on a 600 kW gas turbine, and demonstration of the EvGT cycle started autumn 1998 and will continue, in the present phase, for one year. This thesis presents static and dynamic models for traditional gas turbine components, such as, the compressor, combustor, expander and recuperator. A static model for the humidifier is presented, based on common knowledge for atmospheric humidification. All models were developed for the pilot plant at LTH with the objective to support evaluation of the process and individual

The AgI/II family adhesin AspA is required for respiratory infection by Streptococcus pyogenes.

Directory of Open Access Journals (Sweden)

Linda Franklin

Full Text Available Streptococcus pyogenes (GAS is a human pathogen that causes pharyngitis and invasive diseases such as toxic shock syndrome and sepsis. The upper respiratory tract is the primary reservoir from which GAS can infect new hosts and cause disease. The factors involved in colonisation are incompletely known however. Previous evidence in oral streptococci has shown that the AgI/II family proteins are involved. We hypothesized that the AspA member of this family might be involved in GAS colonization. We describe a novel mouse model of GAS colonization of the nasopharynx and lower respiratory tract to elucidate these interactions. We used two clinical M serotypes expressing AspA, and their aspA gene deletant isogenic mutants in experiments using adherence assays to respiratory epithelium, macrophage phagocytosis and neutrophil killing assays and in vivo models of respiratory tract colonisation and infection. We demonstrated the requirement for AspA in colonization of the respiratory tract. AspA mutants were cleared from the respiratory tract and were deficient in adherence to epithelial cells, and susceptible to phagocytosis. Expression of AspA in the surrogate host Lactococcus lactis protected bacteria from phagocytosis. Our results suggest that AspA has an essential role in respiratory infection, and may function as a novel anti-phagocytic factor.

Membrane humidification--a new method for humidification of respiratory gases in ventilator treatment of neonates.

Science.gov (United States)

Hanssler, L; Tennhoff, W; Roll, C

1992-01-01

A humidifier system for neonatology that functions according to the 'membrane humidification' principle was subjected to a performance test in our laboratory. Humidification and heating of the respiratory gases took place in a module consisting of a net of hollow fibres placed inside the incubator. In 18 measurement combinations flow, respiratory gas temperature, and incubator temperature were varied. At respiratory gas temperatures within the range of 33-37 degrees C the minimum international standard for the absolute air humidity in the respiratory gas was achieved or exceeded in all measurements. No controlled clinical tests regarding the importance and long term effects of different temperatures and different humidity levels in the inspiratory air are yet available for the ventilation treatment of neonates. PMID:1444554

MERGER SIGNATURES IN THE DYNAMICS OF STAR-FORMING GAS

International Nuclear Information System (INIS)

Hung, Chao-Ling; Sanders, D. B.; Hayward, Christopher C.; Smith, Howard A.; Ashby, Matthew L. N.; Martínez-Galarza, Juan R.; Zezas, Andreas; Lanz, Lauranne

2016-01-01

The recent advent of integral field spectrographs and millimeter interferometers has revealed the internal dynamics of many hundreds of star-forming galaxies. Spatially resolved kinematics have been used to determine the dynamical status of star-forming galaxies with ambiguous morphologies, and constrain the importance of galaxy interactions during the assembly of galaxies. However, measuring the importance of interactions or galaxy merger rates requires knowledge of the systematics in kinematic diagnostics and the visible time with merger indicators. We analyze the dynamics of star-forming gas in a set of binary merger hydrodynamic simulations with stellar mass ratios of 1:1 and 1:4. We find that the evolution of kinematic asymmetries traced by star-forming gas mirrors morphological asymmetries derived from mock optical images, in which both merger indicators show the largest deviation from isolated disks during strong interaction phases. Based on a series of simulations with various initial disk orientations, orbital parameters, gas fractions, and mass ratios, we find that the merger signatures are visible for ∼0.2–0.4 Gyr with kinematic merger indicators but can be approximately twice as long for equal-mass mergers of massive gas-rich disk galaxies designed to be analogs of z ∼ 2–3 submillimeter galaxies. Merger signatures are most apparent after the second passage and before the black holes coalescence, but in some cases they persist up to several hundred Myr after coalescence. About 20%–60% of the simulated galaxies are not identified as mergers during the strong interaction phase, implying that galaxies undergoing violent merging process do not necessarily exhibit highly asymmetric kinematics in their star-forming gas. The lack of identifiable merger signatures in this population can lead to an underestimation of merger abundances in star-forming galaxies, and including them in samples of star-forming disks may bias the measurements of disk

Online investigation of respiratory quotients in Pinus sylvestris and Picea abies during drought and shading by means of cavity-enhanced Raman multi-gas spectrometry.

Science.gov (United States)

Hanf, Stefan; Fischer, Sarah; Hartmann, Henrik; Keiner, Robert; Trumbore, Susan; Popp, Jürgen; Frosch, Torsten

2015-07-07

Photosynthesis and respiration are major components of the plant carbon balance. During stress, like drought, carbohydrate supply from photosynthesis is reduced and the Krebs cycle respiration must be fueled with other stored carbon compounds. However, the dynamics of storage use are still unknown. The respiratory quotient (RQ, CO2 released per O2 consumed during respiration) is an excellent indicator of the nature of the respiration substrate. In plant science, however, online RQ measurements have been challenging or even impossible so far due to very small gas exchange fluxes during respiration. Here we apply cavity-enhanced multi-gas Raman spectrometry (CERS) for online in situ RQ measurements in drought-tolerant pine (Pinus sylvestris [L.]) and drought-intolerant spruce (Picea abies [L. H. Karst]). Two different treatments, drought and shading, were applied to reduce photosynthesis and force dependency on stored substrates. Changes in respiration rates and RQ values were continuously monitored over periods of several days with low levels of variance. The results show that both species switched from COH-dominated respiration (RQ = 1.0) to a mixture of substrates during shading (RQ = 0.77-0.81), while during drought only pine did so (RQ = 0.75). The gas phase measurements were complemented by concentration measurements of non-structural carbohydrates and lipids. These first results suggest a physiological explanation for greater drought tolerance in pine. CERS was proven as powerful technique for non-consumptive and precise real-time monitoring of respiration rates and respirational quotients for the investigation of plant metabolism under drought stress conditions that are predicted to increase with future climate change.

SMART phones and the acute respiratory patient.

LENUS (Irish Health Repository)

Gleeson, L

2012-05-01

Definition of Respiratory Failure using PaO2 alone is confounded when patients are commenced on oxygen therapy prior to arterial blood gas (ABG) measurement. Furthermore, classification of Respiratory Failure as Type 1 or Type 2 using PaCO2 alone can give an inaccurate account of events as both types can co-exist. 100 consecutive presentations of acute respiratory distress were assessed initially using PaO2, and subsequently PaO2\\/FiO2 ratio, to diagnose Respiratory Failure. Respiratory Failure cases were classified as Type 1 or Type 2 initially using PaCO2, and subsequently alveolar-arterial (A-a) gradient. Any resultant change in management was documented. Of 100 presentations, an additional 16 cases were diagnosed as Respiratory Failure using PaO2\\/FiO2 ratio in place of PaO2 alone (p = 0.0338). Of 57 cases of Respiratory Failure, 22 cases classified as Type 2 using PaCO2 alone were reclassified as Type 1 using A-a gradient (p < 0.001). Of these 22 cases, management changed in 18.

Vacuum sealing with a spiral grooved gas dynamic seal

International Nuclear Information System (INIS)

Sawada, Tadashi

1979-01-01

Gas dynamic seals with rectangular spiral grooves are studied theoretically taking the effects of sidewalls of the grooves and the effects of gas compressibility into account, and slip boundary conditions are employed. The results are compared with the existing experimental data and the validity of the theory is confirmed over a wide pressure range except for the extremely low pressures. Suggestions are made regarding the choice of the geometrical dimensions, i.e., aspect ratio, helix angle, clearance parameter and groove width ratio. (author)

Measuring the impact of air pollution on respiratory infection risk in China

International Nuclear Information System (INIS)

Tang, Sanyi; Yan, Qinling; Shi, Wei; Wang, Xia; Sun, Xiaodan; Yu, Pengbo; Wu, Jianhong; Xiao, Yanni

2018-01-01

China is now experiencing major public health challenges caused by air pollution. Few studies have quantified the dynamics of air pollution and its impact on the risk of respiratory infection. We conducted an integrated data analysis to quantify the association among air quality index (AQI), meteorological variables and respiratory infection risk in Shaanxi province of China in the period of November 15th, 2010 to November 14th, 2016. Our analysis illustrated a statistically significantly positive correlation between the number of influenza-like illness (ILI) cases and AQI, and the respiratory infection risk has increased progressively with increased AQI with a time lag of 0–3 days. We also developed mathematical models for the AQI trend and respiratory infection dynamics, incorporating AQI-dependent incidence and AQI-based behaviour change interventions. Our combined data and modelling analysis estimated the basic reproduction number for the respiratory infection during the studying period to be 2.4076, higher than the basic reproduction number of the 2009 pandemic influenza in the same province. Our modelling-based simulations concluded that, in terms of respiratory infection risk reduction, the persistent control of emission in the China's blue-sky programme is much more effective than substantial social-economic interventions implemented only during the smog days. - Highlights: • Quantify the dynamics of air pollution, evaluate impact on respiratory infection. • Present a novel methodology through integrating statistic and dynamic models. • The respiratory infection risk has increased with increased air quality index. • Persistent control of emission in China's blue-sky program is much more effective. - This study presented a novel methodology to quantify the dynamics of air pollution and evaluate its impact of on the risk of respiratory infection, and hence to suggest interventions for China's blue-sky programme.

Effects on Pulmonary Vascular Mechanics of Two Different Lung-Protective Ventilation Strategies in an Experimental Model of Acute Respiratory Distress Syndrome.

Science.gov (United States)

Santos, Arnoldo; Gomez-Peñalver, Eva; Monge-Garcia, M Ignacio; Retamal, Jaime; Borges, João Batista; Tusman, Gerardo; Hedenstierna, Goran; Larsson, Anders; Suarez-Sipmann, Fernando

2017-11-01

To compare the effects of two lung-protective ventilation strategies on pulmonary vascular mechanics in early acute respiratory distress syndrome. Experimental study. University animal research laboratory. Twelve pigs (30.8 ± 2.5 kg). Acute respiratory distress syndrome was induced by repeated lung lavages and injurious mechanical ventilation. Thereafter, animals were randomized to 4 hours ventilation according to the Acute Respiratory Distress Syndrome Network protocol or to an open lung approach strategy. Pressure and flow sensors placed at the pulmonary artery trunk allowed continuous assessment of pulmonary artery resistance, effective elastance, compliance, and reflected pressure waves. Respiratory mechanics and gas exchange data were collected. Acute respiratory distress syndrome led to pulmonary vascular mechanics deterioration. Four hours after randomization, pulmonary vascular mechanics was similar in Acute Respiratory Distress Syndrome Network and open lung approach: resistance (578 ± 252 vs 626 ± 153 dyn.s/cm; p = 0.714), effective elastance, (0.63 ± 0.22 vs 0.58 ± 0.17 mm Hg/mL; p = 0.710), compliance (1.19 ± 0.8 vs 1.50 ± 0.27 mL/mm Hg; p = 0.437), and reflection index (0.36 ± 0.04 vs 0.34 ± 0.09; p = 0.680). Open lung approach as compared to Acute Respiratory Distress Syndrome Network was associated with improved dynamic respiratory compliance (17.3 ± 2.6 vs 10.5 ± 1.3 mL/cm H2O; p mechanics similarly. The use of higher positive end-expiratory pressures in the open lung approach strategy did not worsen pulmonary vascular mechanics, improved lung mechanics, and gas exchange but at the expense of a lower cardiac index.

Respiratory physiology during early life.

Science.gov (United States)

Stocks, J

1999-08-01

Despite the rapid adaptation to extrauterine life, the respiratory system of an infant is not simply a miniaturized version of that of an adult, since the rapid somatic growth that occurs during the first year of life is accompanied by major developmental changes in respiratory physiology. The highly compliant chest wall of the infant results in relatively low transpulmonary pressures at end expiration with increased tendency of the small peripheral airways to close during tidal breathing. This not only impairs gas exchange and ventilation-perfusion balance, particularly in dependent parts of the lung, but, together with the small absolute size of the airways, renders the infant and young child particularly susceptible to airway obstruction. Premature airways are highly compliant structures compared with those of mature newborns or adults. This increased compliance can cause airway collapse, resulting in increased airways resistance, flow limitation, poor gas exchange and increased work of breathing. Although there is clear evidence that airway reactivity is present from birth, its role in wheezing lower respiratory tract illnesses in young infants may be overshadowed by pre-existing abnormalities of airway geometry and lung mechanics, or by pathological changes such as airway oedema and mucus hypersecretion. Attempts to assess age-related changes in airway reactivity or response to aerosol therapy in the very young is confounded by changes in breathing patterns and the fact that infants are preferential nose breathers. There is increasing evidence that pre-existing abnormalities of respiratory function, associated with adverse events during foetal life (including maternal smoking during pregnancy), and familial predisposition to wheezing are important determinants of wheezing illnesses during the first years of life. This emphasizes the need to identify and minimize any factors that threaten the normal development of the lung during this critical period if

Dynamics and control of a gas-fired furnace

NARCIS (Netherlands)

Roffel, B.; Rijnsdorp, J.E.

1974-01-01

A non-linear model has been developed for a gas-fired furnace in which oil is heated. The model is applicable from minimum to maximum heat load of the furnace. The dynamics of the model have been compared to experimental results, which were obtained for a pilot-scale furnace. They are in good

Modeling and dynamic control simulation of unitary gas engine heat pump

International Nuclear Information System (INIS)

Zhao Yang; Haibo Zhao; Zheng Fang

2007-01-01

Based on the dynamic model of the gas engine heat pump (GEHP) system, an intelligent control simulation is presented to research the dynamic characteristics of the system in the heating operation. The GEHP system simulation model consists of eight models for its components including a natural gas engine, a compressor, a condenser, an expansion valve, an evaporator, a cylinder jacket heat exchanger, an exhaust gas heat exchanger and an auxiliary heater. The intelligent control model is composed of the prediction controller model and the combined controller model. The Runge-Kutta Fehlberg fourth-fifth order algorithms are used to solve the differential equations. The results show that the model is very effective in analyzing the effects of the control system, and the steady state accuracy of the intelligent control scheme is higher than that of the fuzzy controller

Respiratory trace feature analysis for the prediction of respiratory-gated PET quantification

Science.gov (United States)

Wang, Shouyi; Bowen, Stephen R.; Chaovalitwongse, W. Art; Sandison, George A.; Grabowski, Thomas J.; Kinahan, Paul E.

2014-02-01

The benefits of respiratory gating in quantitative PET/CT vary tremendously between individual patients. Respiratory pattern is among many patient-specific characteristics that are thought to play an important role in gating-induced imaging improvements. However, the quantitative relationship between patient-specific characteristics of respiratory pattern and improvements in quantitative accuracy from respiratory-gated PET/CT has not been well established. If such a relationship could be estimated, then patient-specific respiratory patterns could be used to prospectively select appropriate motion compensation during image acquisition on a per-patient basis. This study was undertaken to develop a novel statistical model that predicts quantitative changes in PET/CT imaging due to respiratory gating. Free-breathing static FDG-PET images without gating and respiratory-gated FDG-PET images were collected from 22 lung and liver cancer patients on a PET/CT scanner. PET imaging quality was quantified with peak standardized uptake value (SUVpeak) over lesions of interest. Relative differences in SUVpeak between static and gated PET images were calculated to indicate quantitative imaging changes due to gating. A comprehensive multidimensional extraction of the morphological and statistical characteristics of respiratory patterns was conducted, resulting in 16 features that characterize representative patterns of a single respiratory trace. The six most informative features were subsequently extracted using a stepwise feature selection approach. The multiple-regression model was trained and tested based on a leave-one-subject-out cross-validation. The predicted quantitative improvements in PET imaging achieved an accuracy higher than 90% using a criterion with a dynamic error-tolerance range for SUVpeak values. The results of this study suggest that our prediction framework could be applied to determine which patients would likely benefit from respiratory motion compensation

Respiratory trace feature analysis for the prediction of respiratory-gated PET quantification

International Nuclear Information System (INIS)

Wang, Shouyi; Chaovalitwongse, W Art; Bowen, Stephen R; Kinahan, Paul E; Sandison, George A; Grabowski, Thomas J

2014-01-01

The benefits of respiratory gating in quantitative PET/CT vary tremendously between individual patients. Respiratory pattern is among many patient-specific characteristics that are thought to play an important role in gating-induced imaging improvements. However, the quantitative relationship between patient-specific characteristics of respiratory pattern and improvements in quantitative accuracy from respiratory-gated PET/CT has not been well established. If such a relationship could be estimated, then patient-specific respiratory patterns could be used to prospectively select appropriate motion compensation during image acquisition on a per-patient basis. This study was undertaken to develop a novel statistical model that predicts quantitative changes in PET/CT imaging due to respiratory gating. Free-breathing static FDG-PET images without gating and respiratory-gated FDG-PET images were collected from 22 lung and liver cancer patients on a PET/CT scanner. PET imaging quality was quantified with peak standardized uptake value (SUV peak ) over lesions of interest. Relative differences in SUV peak between static and gated PET images were calculated to indicate quantitative imaging changes due to gating. A comprehensive multidimensional extraction of the morphological and statistical characteristics of respiratory patterns was conducted, resulting in 16 features that characterize representative patterns of a single respiratory trace. The six most informative features were subsequently extracted using a stepwise feature selection approach. The multiple-regression model was trained and tested based on a leave-one-subject-out cross-validation. The predicted quantitative improvements in PET imaging achieved an accuracy higher than 90% using a criterion with a dynamic error-tolerance range for SUV peak values. The results of this study suggest that our prediction framework could be applied to determine which patients would likely benefit from respiratory motion

Prolonged lateral steep position impairs respiratory mechanics during continuous lateral rotation therapy in respiratory failure.

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Schellongowski, Peter; Losert, Heidrun; Locker, Gottfried J; Laczika, Klaus; Frass, Michael; Holzinger, Ulrike; Bojic, Andja; Staudinger, Thomas

2007-04-01

To establish whether prolonged lateral steep position during continuous rotation therapy leads to improvement on pulmonary gas exchange, respiratory mechanics and hemodynamics. Prospective observational study. Intensive care unit of a university hospital. Twelve consecutive patients suffering from acute lung injury or adult respiratory distress syndrome undergoing continuous rotation therapy. Blood gas analysis, static lung compliance, blood pressure, cardiac index and pulmonary shunt fraction were measured in supine as well as in left and right lateral steep position at 62 degrees during continuous rotation therapy (phase I). Rotation was then stopped for 30 min with the patients in supine position, left and right lateral steep position, and the same measurements were performed every 10 min (phase II). Phase I and II revealed no significant changes in PaO(2)/FiO(2) ratio, mean arterial blood pressure, pulmonary shunt fraction, or cardiac index. Significantly lower static compliance was observed in lateral steep position than in supine position (pposition than in left and right lateral steep position (ppositioning impairs the compliance of the respiratory system. Prolonged lateral steep position does not lead to benefits with respect to oxygenation or hemodynamics. Individual response to the different positions is unpredictable. The pauses in "extreme" positions should be as short as possible.

Effect of respiratory motion on internal radiation dosimetry

Energy Technology Data Exchange (ETDEWEB)

Xie, Tianwu [Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, Geneva 4 CH-1211 (Switzerland); Zaidi, Habib, E-mail: habib.zaidi@hcuge.ch [Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, Geneva 4 CH-1211 (Switzerland); Geneva Neuroscience Center, Geneva University, Geneva CH-1205 (Switzerland); Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen 9700 RB (Netherlands)

2014-11-01

Purpose: Estimation of the radiation dose to internal organs is essential for the assessment of radiation risks and benefits to patients undergoing diagnostic and therapeutic nuclear medicine procedures including PET. Respiratory motion induces notable internal organ displacement, which influences the absorbed dose for external exposure to radiation. However, to their knowledge, the effect of respiratory motion on internal radiation dosimetry has never been reported before. Methods: Thirteen computational models representing the adult male at different respiratory phases corresponding to the normal respiratory cycle were generated from the 4D dynamic XCAT phantom. Monte Carlo calculations were performed using the MCNP transport code to estimate the specific absorbed fractions (SAFs) of monoenergetic photons/electrons, the S-values of common positron-emitting radionuclides (C-11, N-13, O-15, F-18, Cu-64, Ga-68, Rb-82, Y-86, and I-124), and the absorbed dose of {sup 18}F-fluorodeoxyglucose ({sup 18}F-FDG) in 28 target regions for both the static (average of dynamic frames) and dynamic phantoms. Results: The self-absorbed dose for most organs/tissues is only slightly influenced by respiratory motion. However, for the lung, the self-absorbed SAF is about 11.5% higher at the peak exhale phase than the peak inhale phase for photon energies above 50 keV. The cross-absorbed dose is obviously affected by respiratory motion for many combinations of source-target pairs. The cross-absorbed S-values for the heart contents irradiating the lung are about 7.5% higher in the peak exhale phase than the peak inhale phase for different positron-emitting radionuclides. For {sup 18}F-FDG, organ absorbed doses are less influenced by respiratory motion. Conclusions: Respiration-induced volume variations of the lungs and the repositioning of internal organs affect the self-absorbed dose of the lungs and cross-absorbed dose between organs in internal radiation dosimetry. The dynamic

Nonlinear dynamics of a soliton gas: Modified Korteweg–de Vries equation framework

Energy Technology Data Exchange (ETDEWEB)

Shurgalina, E.G., E-mail: eshurgalina@mail.ru [Department of Nonlinear Geophysical Processes, Institute of Applied Physics of the Russian Academy of Sciences, Nizhny Novgorod (Russian Federation); Pelinovsky, E.N. [Department of Nonlinear Geophysical Processes, Institute of Applied Physics of the Russian Academy of Sciences, Nizhny Novgorod (Russian Federation); Department of Applied Mathematics, Nizhny Novgorod State Technical University, Nizhny Novgorod (Russian Federation)

2016-05-27

Dynamics of random multi-soliton fields within the framework of the modified Korteweg–de Vries equation is considered. Statistical characteristics of a soliton gas (distribution functions and moments) are calculated. It is demonstrated that the results sufficiently depend on the soliton gas properties, i.e., whether it is unipolar or bipolar. It is shown that the properties of a unipolar gas are qualitatively similar to the properties of a KdV gas [Dutykh and Pelinovsky (2014) [1

Using respiratory rate and thoracic movement to assess respiratory insufficiency in amyotrophic lateral sclerosis: a preliminary study

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Siirala Waltteri

2012-12-01

Full Text Available Abstract Background Hypoventilation due to respiratory insufficiency is the most common cause of death in amyotrophic lateral sclerosis (ALS and non-invasive ventilation (NIV can be used as a palliative treatment. The current guidelines recommend performing spirometry, and recording nocturnal oxyhemoglobin saturation and arterial blood gas analysis to assess the severity of the hypoventilation. We examined whether the respiratory rate and thoracic movement were reliable preliminary clinical signs in the development of respiratory insufficiency in patients with ALS. Methods We measured the respiratory rate and thoracic movement, performed respiratory function tests and blood gas analysis, and recorded subjective hypoventilation symptoms in 42 ALS patients over a 7-year period. We recommended NIV if the patient presented with hypoventilation matching the current guidelines. We divided patients retrospectively into two groups: those to whom NIV was recommended within 6 months of the diagnosis (Group 1 and those to whom NIV was recommended 6 months after the diagnosis (Group 2. We used the Mann Whitney U test for comparisons between the two groups. Results The mean partial pressure of arterial carbon dioxide in the morning in Group 1 was 6.3 (95% confidence interval 5.6–6.9 kPa and in Group 2 5.3 (5.0–5.6 kPa (p = 0.007. The mean respiratory rate at the time of diagnosis in Group 1 was 21 (18–24 breaths per minute and 16 (14–18 breaths per minute in Group 2 (p = 0.005. The mean thoracic movement was 2.9 (2.2–3.6 cm in Group 1 and 4.0 (3.4–4.8 cm in Group 2 (p = 0.01. We observed no other differences between the groups. Conclusions Patients who received NIV within six months of the diagnosis of ALS had higher respiratory rates and smaller thoracic movement compared with patients who received NIV later. Further studies with larger numbers of patients are needed to establish if these measurements can be used as a marker of hypoventilation

Using respiratory rate and thoracic movement to assess respiratory insufficiency in amyotrophic lateral sclerosis: a preliminary study.

Science.gov (United States)

Siirala, Waltteri; Saaresranta, Tarja; Vuori, Arno; Salanterä, Sanna; Olkkola, Klaus T; Aantaa, Riku

2012-12-27

Hypoventilation due to respiratory insufficiency is the most common cause of death in amyotrophic lateral sclerosis (ALS) and non-invasive ventilation (NIV) can be used as a palliative treatment. The current guidelines recommend performing spirometry, and recording nocturnal oxyhemoglobin saturation and arterial blood gas analysis to assess the severity of the hypoventilation. We examined whether the respiratory rate and thoracic movement were reliable preliminary clinical signs in the development of respiratory insufficiency in patients with ALS. We measured the respiratory rate and thoracic movement, performed respiratory function tests and blood gas analysis, and recorded subjective hypoventilation symptoms in 42 ALS patients over a 7-year period. We recommended NIV if the patient presented with hypoventilation matching the current guidelines. We divided patients retrospectively into two groups: those to whom NIV was recommended within 6 months of the diagnosis (Group 1) and those to whom NIV was recommended 6 months after the diagnosis (Group 2). We used the Mann Whitney U test for comparisons between the two groups. The mean partial pressure of arterial carbon dioxide in the morning in Group 1 was 6.3 (95% confidence interval 5.6-6.9) kPa and in Group 2 5.3 (5.0-5.6) kPa (p = 0.007). The mean respiratory rate at the time of diagnosis in Group 1 was 21 (18-24) breaths per minute and 16 (14-18) breaths per minute in Group 2 (p = 0.005). The mean thoracic movement was 2.9 (2.2-3.6) cm in Group 1 and 4.0 (3.4-4.8) cm in Group 2 (p = 0.01). We observed no other differences between the groups. Patients who received NIV within six months of the diagnosis of ALS had higher respiratory rates and smaller thoracic movement compared with patients who received NIV later. Further studies with larger numbers of patients are needed to establish if these measurements can be used as a marker of hypoventilation in ALS.

A System Dynamics Analysis of Investment, Technology and Policy that Affect Natural Gas Exploration and Exploitation in China

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Jianzhong Xiao

2017-01-01

Full Text Available Natural gas has an increasing role in Chinese energy transformation. We present a system dynamics model of the natural gas industry in China. A new system dynamics model for natural gas companies based on reserve exploration and well construction as well as investment dynamics is proposed. The contribution of the paper is to analyze the influence of technology, investment and policy factors on the natural gas industry. We found that the dynamics of the main variables, including gas policy, cost of investment, accounting depreciation and exploitation technology, are sensitive to the sustainable development of resources. The simulations and results presented here will be helpful for government to reform policies, and for upstream companies to make decisions.

X-ray picture of the respiratory distress syndrome (shock lung)

International Nuclear Information System (INIS)

Sharov, B.K.; Ana'ev, V.M.; Kiseleva, M.N.

1993-01-01

X-Ray picture of the respiratory distress syndrome (shock lung) in 78 patients exposed to high temperature as a result of gas condensate explosion is analyzed. X-ray and morphologic fundings in these patients are compared to those in 13 similar patients in whom acute respiratory failure developed because of other causes. Morphologic basis of the4 majority of x-ray signs of acute respiratory distress has been investigated. A relationship between respiratory distress syndrome development and changes in the heart size has been revealed, which may serve the prediction criterion

Interring Gas Dynamic Analysis of Piston in a Diesel Engine considering the Thermal Effect

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Wanyou Li

2015-01-01

Full Text Available Understanding the interaction between ring dynamics and gas transport in ring pack systems is crucial and needs to be imperatively studied. The present work features detailed interring gas dynamics of piston ring pack behavior in internal combustion engines. The model is developed for a ring pack with four rings. The dynamics of ring pack are simulated. Due to the fact that small changes in geometry of the grooves and lands would have a significant impact on the interring gas dynamics, the thermal deformation of piston has been considered during the ring pack motion analysis in this study. In order to get the temperature distribution of piston head more quickly and accurately, an efficient method utilizing the concept of inverse heat conduction is presented. Moreover, a sensitive analysis based on the analysis of partial regression coefficients is presented to investigate the effect of groove parameters on blowby.

Respiratory muscle function and exercise limitation in patients with chronic obstructive pulmonary disease: a review.

Science.gov (United States)

Charususin, Noppawan; Dacha, Sauwaluk; Gosselink, Rik; Decramer, Marc; Von Leupoldt, Andreas; Reijnders, Thomas; Louvaris, Zafeiris; Langer, Daniel

2018-01-01

Respiratory muscle dysfunction is common and contributes to dyspnea and exercise limitation in patients with chronic obstructive pulmonary disease (COPD). Improving dynamic function of respiratory muscles during exercise might help to reduce symptoms and improve exercise capacity. Areas covered: The aims of this review are to 1) summarize physiological mechanisms linking respiratory muscle dysfunction to dyspnea and exercise limitation; 2) provide an overview of available therapeutic approaches to better maintain load-capacity balance of respiratory muscles during exercise; and 3) to summarize current knowledge on potential mechanisms explaining effects of interventions aimed at optimizing dynamic respiratory muscle function with a special focus on inspiratory muscle training. Expert commentary: Several mechanisms which are potentially linking improvements in dynamic respiratory muscle function to symptomatic and functional benefits have not been studied so far in COPD patients. Examples of underexplored areas include the study of neural processes related to the relief of acute dyspnea and the competition between respiratory and peripheral muscles for limited energy supplies during exercise. Novel methodologies are available to non-invasively study these mechanisms. Better insights into the consequences of dynamic respiratory muscle dysfunction will hopefully contribute to further refine and individualize therapeutic approaches in patients with COPD.

Price dynamics of natural gas and the regional methanol markets

International Nuclear Information System (INIS)

Masih, A. Mansur M.; Albinali, Khaled; DeMello, Lurion

2010-01-01

A 'methanol economy' based mainly on natural gas as a feedstock has a lot of potential to cope with the current and ongoing concerns for energy security along with the reduction of CO-2 emissions. It is, therefore, important to examine the price dynamics of methanol in order to ascertain whether the price of methanol is mainly natural-gas-cost driven or demand driven in the context of different regions. This paper is the first attempt to investigate the following: (1) is the natural gas price significantly related to the regional methanol prices in the Far East, United States and Europe? (2) who drives the regional methanol prices? The paper is motivated by the recent and growing debate on the lead-lag relationship between natural gas and methanol prices. Our findings, based on the most recently developed 'long-run structural modelling' and subject to the limitations of the study, tend to suggest: (1) natural gas price is cointegrated with the regional methanol prices, (2) our within-sample error-correction model results tend to indicate that natural gas was driving the methanol prices in Europe and the United States but not in the Far East. These results are consistent, during most of the period under review (1998.5-2007.3), with the surge in demand for methanol throughout the Far East, particularly in China, Taiwan and South Korea, which appears to have played a relatively more dominant role in the Far East compared to that in Europe and the United States within the framework of the dynamic interactions of input and product prices. However, during the post-sample forecast period as evidenced in our variance decompositions analysis, the emergence of natural gas as the main driver of methanol prices in all three continents is consistent with the recent surge in natural gas price fueled mainly, among others, by the strong hedging activities in the natural gas futures/options as well as refining tightness (similar to those that were happening in the crude oil markets

Effects of vertical positioning on gas exchange and lung volumes in acute respiratory distress syndrome.

Science.gov (United States)

Richard, Jean-Christophe M; Maggiore, Salvatore Maurizio; Mancebo, Jordi; Lemaire, François; Jonson, Bjorn; Brochard, Laurent

2006-10-01

Supine position may contribute to the loss of aerated lung volume in patients with acute respiratory distress syndrome (ARDS). We hypothesized that verticalization increases lung volume and improves gas exchange by reducing the pressure surrounding lung bases. Prospective observational physiological study in a medical ICU. In 16 patients with ARDS we measured arterial blood gases, pressure-volume curves of the respiratory system recorded from positive-end expiratory pressure (PEEP), and changes in lung volume in supine and vertical positions (trunk elevated at 45 degrees and legs down at 45 degrees ). Vertical positioning increased PaO(2) significantly from 94+/-33 to 142+/-49 mmHg, with an increase higher than 40% in 11 responders. The volume at 20 cmH(2)O measured on the PV curve from PEEP increased using the vertical position only in responders (233+/-146 vs. -8+/-9 1ml in nonresponders); this change was correlated to oxygenation change (rho=0.55). End-expiratory lung volume variation from supine to vertical and 1 h later back to supine, measured in 12 patients showed a significant increase during the 1-h upright period in responders (n=7) but not in nonresponders (n=5; 215+/-220 vs. 10+/-22 ml), suggesting a time-dependent recruitment. Vertical positioning is a simple technique that may improve oxygenation and lung recruitment in ARDS patients.

A versatile hydraulically operated respiratory servo system for ventilation and lung function testing.

Science.gov (United States)

Meyer, M; Slama, H

1983-09-01

A description is given of the design and performance of a microcomputer-controlled respiratory servo system that incorporates the characteristics of a mechanical ventilator and also allows the performance of a multitude of test procedures required for assessment of pulmonary function in paralyzed animals. The device consists of a hydraulically operated cylinder-piston assembly and solenoid valves that direct inspiratory and expiratory gas flow and also enable switching to different test gas sources. The system operates as a volume-flow-preset ventilator but may be switched to other operational cycling modes. Gas flow rates may be constant or variable. The system operates as an assister-controller and, combined with a gas analyzer, can function as a "demand" ventilator allowing for set-point control of end-tidal PCO2 and PO2. Complex breathing maneuvers for a variety of single- and multiple-breath lung function tests are automatically performed. Because of the flexibility in selection and timing of respiratory parameters, the system is particularly suitable for respiratory gas studies.

Effect of waveforms of inspired gas tension on the respiratory oscillations of carotid body discharge.

Science.gov (United States)

Kumar, P; Nye, P C; Torrance, R W

1991-07-01

The responses of carotid body chemoreceptor discharge to repeated ramps (20- to 60-s forcing cycle durations) of inspired gas tensions were studied in spontaneously breathing and in artificially ventilated pentobarbitone-anesthetized cats. In all animals the mean intensity of chemoreceptor discharge followed the frequency of the forcing cycle, and superimposed on this were oscillations at the frequency of ventilation (breath-by-breath oscillations). The amplitude of the breath-by-breath oscillations in discharge was often large, and it waxed and waned with the forcing cycle. It was greatest when the mean level of discharge was falling and smallest near the peak of mean discharge. No qualitative differences were observed between PO2-alone forcing in constant normocapnia and PCO2-alone forcing in constant hypoxia. The variation in the amplitudes of breath-by-breath oscillations was shown to be due primarily to variations in the amplitudes of the downslope component of the discharge oscillation. Variations in the upslope component of individual oscillations were small. The factors responsible for the breath-by-breath oscillations are discussed, and it is concluded that the shape of the waveform of arterial gas tensions that stimulate the peripheral chemoreceptors departs markedly from that of a line joining end-tidal gas tensions. This causes breath-by-breath oscillations of discharge to be very large after an "off" stimulus. Reflex studies involving the forcing of respiratory gases should therefore include consideration of these effects.

The articulation of Mexico into the dynamics of competition of the North American natural gas market

International Nuclear Information System (INIS)

Elizalde Baltierra, A.

2002-07-01

Deregulation is at the origin of the new dynamics of competition in the natural gas industry. The United States and Canada were the pioneer countries to suffer these changes. In fact, their natural gas markets today function in a very similar way: i) the private sector takes a place as large as possible, and ii)competition is developed within the three segments of the gas value, especially at the upstream level (emergence of hubs, spot and financial markets,...). In Mexico, its downstream gas activities (transportation, storage and distribution) were liberalized in 1995 in order to attract private investments and to develop the gas sector that has historically been operated under State control. Gas upstream operations remain reserved by the Constitution to the national oil company Petroleos Mexicanos (PEMEX). This thesis develops an evaluation framework of the articulation of Mexico into the dynamics of competition of the North American natural gas market, based on the structure-conduct-performance paradigm. In the first part, all North American's natural gas industries base conditions are analyzed. We examine in the second part, the deregulation and articulation of the dynamics of competition of the American and Canadian gas industries. Finally, in the third part we analyze the main elements of the articulation of Mexico into the dynamics of competition of United States and Canada's gas industries. Furthermore, we evaluate the impact of three of these elements (the economic growth, the electric power generation sector and eventually opening to private investments of gas upstream activities) on the adjustment of gas supply and demand in Mexico to the year 2020. (author)

Shale Gas in Poland: an Analysis of Tax Mechanisms and Dynamic Interactions

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Dawid Walentek

2016-12-01

Full Text Available This is a preliminary research into possible taxation mechanisms for firms that will be operating in the shale gas industry in Poland and potential market interactions between the incumbents and the entrants. The study places focus on the level of welfare and it includes a static and a dynamic analysis. The result of the former is that the lump sum tax is the first best of all considered tax mechanisms for the Polish shale gas from the welfare perspective. The second best option for taxation is a combination of the current CIT rate and a windfall profit tax. In respect to the dynamic analysis, the results suggest that Gazprom can remain the market leader in Poland even if the shale gas producers start to operate, due to the sequential character of the competition in the Polish natural gas market. Counterintuitively, it will not come at the expenses of the consumers in Poland and it can bring potential welfare gains

On the Gas Dynamics of Inert-Gas-Assisted Laser Cutting of Steel Plate

Science.gov (United States)

Brandt, A. D.; Settles, G. S.; Scroggs, S. D.

1996-11-01

Laser beam cutting of sheet metal requires an assist gas to blow away the molten material. Since the assist-gas dynamics influences the quality and speed of the cut, the orientation of the gas nozzle with respect to the kerf is also expected to be important. A 1 kW cw CO2 laser with nitrogen assist gas was used to cut mild steel sheet of 1 to 4 mm thickness, using a sonic coaxial nozzle as a baseline. Off-axis nozzles were oriented from 20 deg to 60 deg from normal with exit Mach numbers from 1 to 2.4. Results showed maximum cutting speed at a 40 deg nozzle orientation. Shadowgrams of a geometrically-similar model kerf then revealed a separated shock wave-boundary layer interaction within the kerf for the (untilted) coaxial nozzle case. This was alleviated, resulting in a uniform supersonic flow throughout the kerf and consequent higher cutting speeds, by tilting the nozzle between 20 deg and 45 deg from the normal. This result did not depend upon the exit Mach number of the nozzle. (Research supported by NSF Grant DMI-9400119.)

Effect of respiratory function training on respiratory function of patients with severe cerebrovascular disease

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Ming GUO

2017-07-01

Full Text Available Objective To investigate the effect of respiratory function training on respiratory function and conscious state of patients with severe cerebrovascular disease (SCVD.  Methods A total of 27 patients with SCVD were divided into control group (N = 17 and observation group (N = 10. Control group received routine drug and rehabilitation treatment, and observation group was added respiratory function training based on routine treatment. The respiratory rate, tidal volume (TV, heart rate, blood pressure and artery oxygen saturation (SaO2 of patients were monitored by breathing machine before and after 4-week treatment. Meanwhile, arterial blood gas analysis was used to detect arterial partial pressure of oxygen (PaO2, oxygenation index, partial pressure of carbon dioxide (PaCO2 and pH value. At the same time, Glasgow Coma Scale (GCS was used to evaluate the conscious state of patients.  Results All patients successfully completed 4-week rehabilitation training, without asphyxia, arrhythmia or other adverse events. Compared with before training, the respiratory rate (P = 0.006 and pH value (P = 0.010 were significantly decreased, while SaO2 (P = 0.001, oxygenation index (P = 0.000 and GCS scores (P = 0.004, 0.017 were significantly increased in both groups of patients after training. There was no statistically significant difference between 2 groups on respiratory function indexes and GCS scores after training (P > 0.05, for all. Conclusions Respiratory function training did not significantly improve the respiratory function and conscious state of patients with SCVD, yet to be further studied. Randomized controlled clinical trials with larger, layered samples and long-term prognosis observation are needed. Examination method of respiratory function of SCVD patients is also a topic to be explored.  DOI: 10.3969/j.issn.1672-6731.2017.04.007

A Dynamic Model of the Combined Electricity and Natural Gas Markets

DEFF Research Database (Denmark)

Jenkins, Sandra; Annaswamy, Anuradha M.; Hansen, Jacob

2015-01-01

With the shale gas revolution, coal retirements, environmental regulations, and increasing renewable energy resources, the interdependency of natural gas and electricity has grown significantly. Interdependency challenges, such as mismatched market schedules and disparate market operations, require...... quantitative modeling in order to garner insights into the effectiveness of various solutions. In this paper, a quantitative model with a dynamic market mechanism is proposed to evaluate the effects of the fuel uncertainty of natural gas-fired power plants on Social Welfare. The results of the model show...

Dynamical heterogeneity in a glass-forming ideal gas.

Science.gov (United States)

Charbonneau, Patrick; Das, Chinmay; Frenkel, Daan

2008-07-01

We conduct a numerical study of the dynamical behavior of a system of three-dimensional "crosses," particles that consist of three mutually perpendicular line segments of length sigma rigidly joined at their midpoints. In an earlier study [W. van Ketel, Phys. Rev. Lett. 94, 135703 (2005)] we showed that this model has the structural properties of an ideal gas, yet the dynamical properties of a strong glass former. In the present paper we report an extensive study of the dynamical heterogeneities that appear in this system in the regime where glassy behavior sets in. On the one hand, we find that the propensity of a particle to diffuse is determined by the structure of its local environment. The local density around mobile particles is significantly less than the average density, but there is little clustering of mobile particles, and the clusters observed tend to be small. On the other hand, dynamical susceptibility results indicate that a large dynamical length scale develops even at moderate densities. This suggests that propensity and other mobility measures are an incomplete measure of the dynamical length scales in this system.

The promising gas-dynamic schemes of vacuum deposition from the supersonic gas mixture flows

International Nuclear Information System (INIS)

Maltsev, R V; Rebrov, A K

2008-01-01

Gas jet deposition (GJD) becomes promising method of thin film and nanoparticle deposition. This paper is focused on elaboration of new methods of GJD based on different gas dynamic schemes of flow formation and interaction with substrate. Using direct statistical simulation method, the analysis was performed for: a) interaction of the jet from the sonic nozzle with a substrate; b) fan flow in the result of interaction of two opposite jets; c) convergent flow from the ring nozzle, directional to the axis; d) interaction of the jet after convergent flow with the substrate; e) fan flow in the result of interaction of two opposite jets after convergent expansion

Effect of adjuvant noninvasive positive pressure ventilation on blood gas parameters, cardiac function and inflammatory state in patients with COPD and type II respiratory failure

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You-Ming Zhu1

2017-03-01

Full Text Available Objective: T o analyze the effect of adjuvant noninvasive positive pressure ventilation on blood gas parameters, cardiac function and inflammatory state in patients with chronic obstructive pulmonary disease (COPD and type II respiratory failure. Methods: 90 patients with COPD and type II respiratory failure were randomly divided into observation group and control group (n=45. Control group received conventional therapy, observation group received conventional therapy + adjuvant noninvasive positive pressure ventilation, and differences in blood gas parameters, cardiac function, inflammatory state, etc., were compared between two groups of patients 2 weeks after treatment. Results: Arterial blood gas parameters pH and alveolar-arterial partial pressure of oxygen [P(A-aO2] levels of observation group were higher than those of control group while, potassium ion (K+, chloride ion (Cl﹣ and carbon dioxide combining power (CO2CP levels were lower than those of control group 2 weeks after treatment; echocardiography parameters Doppler-derived tricuspid lateral annular systolic velocity (DTIS and pulmonary arterial velocity (PAV levels were lower than those of control group (P＜0.05 while pulmonary artery accelerating time (PAACT, left ventricular enddiastolic dimension (LVDd and right atrioventricular tricuspid annular plane systolic excursion (TAPSE levels were higher than those of control group (P＜0.05; serum cardiac function indexes adiponectin (APN, Copeptin, N-terminal pro-B-type natriuretic peptide (NT-proBNP, cystatin C (CysC, growth differentiation factor-15 (GDF-15 and heart type fatty acid binding protein (H-FABP content were lower than those of control group (P＜0.05; serum inflammatory factors hypersensitive C-reactive protein (hs-CRP, tumor necrosis factor-α (TNF-α, interleukin-1β (IL-1β, IL-8, IL-10, and transforming growth factor-β1 (TGF-β1 content were lower than those of control group (P＜0.05. Conclusions: Adjuvant

Respiratory diseases and their effects on respiratory function and exercise capacity.

Science.gov (United States)

Van Erck-Westergren, E; Franklin, S H; Bayly, W M

2013-05-01

Given that aerobic metabolism is the predominant energy pathway for most sports, the respiratory system can be a rate-limiting factor in the exercise capacity of fit and healthy horses. Consequently, respiratory diseases, even in mild forms, are potentially deleterious to any athletic performance. The functional impairment associated with a respiratory condition depends on the degree of severity of the disease and the equestrian discipline involved. Respiratory abnormalities generally result in an increase in respiratory impedance and work of breathing and a reduced level of ventilation that can be detected objectively by deterioration in breathing mechanics and arterial blood gas tensions and/or lactataemia. The overall prevalence of airway diseases is comparatively high in equine athletes and may affect the upper airways, lower airways or both. Diseases of the airways have been associated with a wide variety of anatomical and/or inflammatory conditions. In some instances, the diagnosis is challenging because conditions can be subclinical in horses at rest and become clinically relevant only during exercise. In such cases, an exercise test may be warranted in the evaluation of the patient. The design of the exercise test is critical to inducing the clinical signs of the problem and establishing an accurate diagnosis. Additional diagnostic techniques, such as airway sampling, can be valuable in the diagnosis of subclinical lower airway problems that have the capacity to impair performance. As all these techniques become more widely used in practice, they should inevitably enhance veterinarians' diagnostic capabilities and improve their assessment of treatment effectiveness and the long-term management of equine athletes. © 2013 EVJ Ltd.

The role of the dynamic pressure in stationary heat conduction of a rarefied polyatomic gas

Energy Technology Data Exchange (ETDEWEB)

Arima, Takashi, E-mail: arima@kanagawa-u.ac.jp [Department of Mechanical Engineering, Faculty of Engineering, Kanagawa University, Yokohama 221-8686 (Japan); Barbera, Elvira, E-mail: ebarbera@unime.it [Department of Mathematics and Computer Science, University of Messina, V.le F. D' Alcontres 31, 98166 Messina (Italy); Brini, Francesca, E-mail: francesca.brini@unibo.it [Department of Mathematics, University of Bologna, via Saragozza 8, 40123 Bologna (Italy); Sugiyama, Masaru, E-mail: sugiyama@nitech.ac.jp [Graduate School of Engineering, Nagoya Institute of Technology, Nagoya 466-8555 (Japan)

2014-07-18

The effect of the dynamic pressure (non-equilibrium pressure) on stationary heat conduction in a rarefied polyatomic gas at rest is elucidated by the theory of extended thermodynamics. It is shown that this effect is observable in a non-polytropic gas. Numerical studies are presented for a para-hydrogen gas as a typical example. - Highlights: • Heat transfer problem in polyatomic rarefied gases is studied in different domains. • Non-zero dynamic pressure is predicted in non-polytropic gases. • The effect of dynamic pressure can be observed indirectly in an experiment. • The case of para-hydrogen is analyzed as an example. • Navier–Stokes, Fourier, and Extended Thermodynamics predictions are compared.

Cardio-respiratory interactions and relocation of heartbeats within the respiratory cycle during spontaneous and paced breathing

International Nuclear Information System (INIS)

Lopes, T C; Beda, A; Granja-Filho, P C N; Jandre, F C; Giannella-Neto, A

2011-01-01

The capability of respiratory sinus arrhythmia (RSA) to generate privileged locations for the occurrence of R-peaks within the respiratory cycle has been questioned in recent works, challenging the hypothesis that RSA might play a role in improving pulmonary gas exchange. We assessed such a capability submitting healthy humans to spontaneous and paced breathing (SB and PB) protocols, estimating the fraction of beats occurring during inspiration, at low, medium, and high respiratory volumes, and during the first and second half of inspiration and expiration. Then, the same fractions were computed assuming a random uniform distribution of heartbeats, and the differences were compared. The results found are as follows: (1) during PB at 6 rpm, heartbeats redistribute toward inspiration; (2) during SB and PB at 12 rpm, heartbeats tend to cluster when respiratory volume is high; (3) since such redistributions are limited in magnitude, it is possible that its physiological relevance is marginal, for instance, in terms of within-cycle variations in lung perfusion; (4) two groups of subjects with considerably different levels of RSA showed similar redistribution of heartbeats, suggesting that this phenomenon might be an underlying effect of the overall cardio-respiratory interactions, and not directly of RSA

Frequency of respiratory virus infections and next-generation analysis of influenza A/H1N1pdm09 dynamics in the lower respiratory tract of patients admitted to the ICU.

Directory of Open Access Journals (Sweden)

Antonio Piralla

Full Text Available Recent molecular diagnostic methods have significantly improved the diagnosis of viral pneumonia in intensive care units (ICUs. It has been observed that 222G/N changes in the HA gene of H1N1pdm09 are associated with increased lower respiratory tract (LRT replication and worse clinical outcome. In the present study, the frequency of respiratory viruses was assessed in respiratory samples from 88 patients admitted to 16 ICUs during the 2014-2015 winter-spring season in Lombardy. Sixty-nine out of 88 (78.4% patients were positive for a respiratory viral infection at admission. Of these, 57/69 (82.6% were positive for influenza A (41 A/H1N1pdm09 and 15 A/H3N2, 8/69 (11.6% for HRV, 2/69 (2.9% for RSV and 2/69 (2.9% for influenza B. Phylogenetic analysis of influenza A/H1N1pdm09 strains from 28/41 ICU-patients and 21 patients with mild respiratory syndrome not requiring hospitalization, showed the clear predominance of subgroup 6B strains. The median influenza A load in LRT samples of ICU patients was higher than that observed in the upper respiratory tract (URT (p<0.05. Overall, a greater number of H1N1pdm09 virus variants were observed using next generation sequencing on partial HA sequences (codons 180-286 in clinical samples from the LRT as compared to URT. In addition, 222G/N/A mutations were observed in 30% of LRT samples from ICU patients. Finally, intra-host evolution analysis showed the presence of different dynamics of viral population in LRT of patients hospitalized in ICU with a severe influenza infection.

Dynamic Gas Flow Effects on the ESD of Aerospace Vehicle Surfaces

Science.gov (United States)

Hogue, Michael D.; Kapat, Jayanta; Ahmed, Kareem; Cox, Rachel E.; Wilson, Jennifer G.; Calle, Luz M.; Mulligan, Jaysen

2016-01-01

The purpose of this work is to develop a dynamic version of Paschen's Law that takes into account the flow of ambient gas past aerospace vehicle surfaces. However, the classic Paschen's Law does not take into account the flow of gas of an aerospace vehicle, whose surfaces may be triboelectrically charged by dust or ice crystal impingement, traversing the atmosphere. The basic hypothesis of this work is that the number of electron-ion pairs created per unit distance by the electric field between the electrodes is mitigated by the electron-ion pairs removed per unit distance by the flow of gas. The revised Paschen equation must be a function of the mean velocity, v(sub xm), of the ambient gas and reduces to the classical version of Paschen's law when the gas mean velocity, v(sub xm) = 0. New formulations of Paschen's Law, taking into account Mach number and dynamic pressure, derived by the authors, will be discussed. These equations will be evaluated by wind tunnel experimentation later this year. Based on the results of this work, it is hoped that the safety of aerospace vehicles will be enhanced with a redefinition of electrostatic launch commit criteria. It is also possible that new products, such as new anti-static coatings, may be formulated from this data.

Respiratory health and lung function in Chinese restaurant kitchen workers.

Science.gov (United States)

Wong, Tze Wai; Wong, Andromeda H S; Lee, Frank S C; Qiu, Hong

2011-10-01

To measure air pollutant concentrations in Chinese restaurant kitchens using different stove types and assess their influence on workers' respiratory health. 393 kitchen workers from 53 Chinese restaurants were surveyed over 16 months: 115 workers from 21 restaurants using only electric stoves and 278 workers from 32 restaurants using only gas stoves. Workers were interviewed about their respiratory symptoms and had their lung function tested. Concentrations of nitric oxide (NO), nitrogen dioxide (NO(2)), carbon monoxide (CO), carbon dioxide (CO(2)), methane (CH(4)), non-methane hydrocarbons (NMHC), total volatile organic compounds (TVOC) and fine particulate matter (PM(2.5)) were measured using portable monitors and air-bag sampling. Temperature and noise levels were assessed. Median concentrations of NO, NO(2) and CO were 7.4, 1.5 and 1.6 times higher in gas-fuelled kitchens than in electric ones and average concentrations of PM(2.5) and TVOC were 81% and 78% higher, respectively. Differences were smaller for CH(4) and NMHC. Electricity-run kitchens were 4.5°C cooler and 9 dBA less noisy than gas-fuelled ones. Workers using electric cookers had significantly better lung function than their gas-using counterparts and their mean FEV(1) and FVC values were 5.4% and 3.8% higher, respectively, after adjustment for confounders. Wheeze, phlegm, cough and sore throat were more prevalent in workers using gas. The adjusted OR for having phlegm regularly was significantly higher. The poorer lung function and higher prevalence of respiratory symptoms among workers in gas-fuelled kitchens compared to those in electricity-powered kitchens may be associated with exposure to higher concentrations of toxic air pollutants generated during gas cooking.

Evaluation of exercise-respiratory system modifications and integration schemes for physiological systems

Science.gov (United States)

Gallagher, R. R.

1974-01-01

Exercise subroutine modifications are implemented in an exercise-respiratory system model yielding improvement of system response to exercise forcings. A more physiologically desirable respiratory ventilation rate in addition to an improved regulation of arterial gas tensions and cerebral blood flow is observed. A respiratory frequency expression is proposed which would be appropriate as an interfacing element of the respiratory-pulsatile cardiovascular system. Presentation of a circulatory-respiratory system integration scheme along with its computer program listing is given. The integrated system responds to exercise stimulation for both nonstressed and stressed physiological states. Other integration possibilities are discussed with respect to the respiratory, pulsatile cardiovascular, thermoregulatory, and the long-term circulatory systems.

A Computation Fluid Dynamic Model for Gas Lift Process Simulation in a Vertical Oil Well

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Kadivar Arash

2017-03-01

Full Text Available Continuous gas-lift in a typical oil well was simulated using computational fluid dynamic (CFD technique. A multi fluid model based on the momentum transfer between liquid and gas bubbles was employed to simulate two-phase flow in a vertical pipe. The accuracy of the model was investigated through comparison of numerical predictions with experimental data. The model then was used to study the dynamic behaviour of the two-phase flow around injection point in details. The predictions by the model were compared with other empirical correlations, as well. To obtain an optimum condition of gas-lift, the influence of the effective parameters including the quantity of injected gas, tubing diameter and bubble size distribution were investigated. The results revealed that increasing tubing diameter, the injected gas rate and decreasing bubble diameter improve gas-lift performance.

Minimum concentrations of NO/sub 2/ causing acute effects on the respiratory gas exchange and airway-resistance in patients with chronic bronchitis

Energy Technology Data Exchange (ETDEWEB)

von Nieding, G; Wagner, M; Krekeler, H; Smidt, U; Muysers, K

1971-01-01

Nitrogen dioxide-air mixtures containing 0.5 to 5.0 ppM NO/sub 2/ were inhaled by 88 patients with chronic bronchitis over a 15-minute period for a total of 30 breaths during studies investigating the effects of the gas on airway resistance and respiratory gas exchange. End-expiratory oxygen pressures remained nearly constant during inhalation of 4 or 5 ppM NO/sub 2/, though significant decreases in arterial oxygen pressure accompanied by increases in end-expiratory-arterial oxygen pressure difference occurred. Inhalation of 2 ppM NO/sub 2/ did not decrease arterial oxygen pressure. Airway resistances increased significantly down to 1.5 ppM NO/sub 2/ concentrations. Lower concentrations caused no significant effects.

Respiratory effort from the photoplethysmogram.

Science.gov (United States)

Addison, Paul S

2017-03-01

The potential for a simple, non-invasive measure of respiratory effort based on the pulse oximeter signal - the photoplethysmogram or 'pleth' - was investigated in a pilot study. Several parameters were developed based on a variety of manifestations of respiratory effort in the signal, including modulation changes in amplitude, baseline, frequency and pulse transit times, as well as distinct baseline signal shifts. Thirteen candidate parameters were investigated using data from healthy volunteers. Each volunteer underwent a series of controlled respiratory effort maneuvers at various set flow resistances and respiratory rates. Six oximeter probes were tested at various body sites. In all, over three thousand pleth-based effort-airway pressure (EP) curves were generated across the various airway constrictions, respiratory efforts, respiratory rates, subjects, probe sites, and the candidate parameters considered. Regression analysis was performed to determine the existence of positive monotonic relationships between the respiratory effort parameters and resulting airway pressures. Six of the candidate parameters investigated exhibited a distinct positive relationship (poximeter probe and an ECG (P2E-Effort) and the other using two pulse oximeter probes placed at different peripheral body sites (P2-Effort); and baseline shifts in heart rate, (BL-HR-Effort). In conclusion, a clear monotonic relationship was found between several pleth-based parameters and imposed respiratory loadings at the mouth across a range of respiratory rates and flow constrictions. The results suggest that the pleth may provide a measure of changing upper airway dynamics indicative of the effort to breathe. Copyright © 2017 The Author. Published by Elsevier Ltd.. All rights reserved.

Influence of a Gas Exchange Correction Procedure on Resting Metabolic Rate and Respiratory Quotient in Humans.

Science.gov (United States)

Galgani, Jose E; Castro-Sepulveda, Mauricio A

2017-11-01

The aim of this study was to determine the influence of a gas exchange correction protocol on resting metabolic rate (RMR) and respiratory quotient (RQ), assessed by a Vmax Encore 29n metabolic cart (SensorMedics Co., Yorba Linda, California) in overnight fasted and fed humans, and to assess the predictive power of body size for corrected and uncorrected RMR. Healthy participants (23 M/29 F; 34 ± 9 years old; 26.3 ± 3.7 kg/m 2 ) ingested two 3-hour-apart glucose loads (75 g). Indirect calorimetry was conducted before and hourly over a 6-hour period. Immediately after indirect calorimetry assessment, gas exchange was simulated through high-precision mass-flow regulators, which permitted the correction of RMR and RQ values. Uncorrected and corrected RMR and RQ were directly related at each time over the 6-hour period. However, uncorrected versus corrected RMR was 6.9% ± 0.5% higher (128 ± 7 kcal/d; P exchange in humans over a 6-hour period is feasible and provides information of improved accuracy. © 2017 The Obesity Society.

Liquid gating elastomeric porous system with dynamically controllable gas/liquid transport.

Science.gov (United States)

Sheng, Zhizhi; Wang, Honglong; Tang, Yongliang; Wang, Miao; Huang, Lizhi; Min, Lingli; Meng, Haiqiang; Chen, Songyue; Jiang, Lei; Hou, Xu

2018-02-01

The development of membrane technology is central to fields ranging from resource harvesting to medicine, but the existing designs are unable to handle the complex sorting of multiphase substances required for many systems. Especially, the dynamic multiphase transport and separation under a steady-state applied pressure have great benefits for membrane science, but have not been realized at present. Moreover, the incorporation of precisely dynamic control with avoidance of contamination of membranes remains elusive. We show a versatile strategy for creating elastomeric microporous membrane-based systems that can finely control and dynamically modulate the sorting of a wide range of gases and liquids under a steady-state applied pressure, nearly eliminate fouling, and can be easily applied over many size scales, pressures, and environments. Experiments and theoretical calculation demonstrate the stability of our system and the tunability of the critical pressure. Dynamic transport of gas and liquid can be achieved through our gating interfacial design and the controllable pores' deformation without changing the applied pressure. Therefore, we believe that this system will bring new opportunities for many applications, such as gas-involved chemical reactions, fuel cells, multiphase separation, multiphase flow, multiphase microreactors, colloidal particle synthesis, and sizing nano/microparticles.

The effect of gas dynamics on semi-analytic modelling of cluster galaxies

Science.gov (United States)

Saro, A.; De Lucia, G.; Dolag, K.; Borgani, S.

2008-12-01

We study the degree to which non-radiative gas dynamics affect the merger histories of haloes along with subsequent predictions from a semi-analytic model (SAM) of galaxy formation. To this aim, we use a sample of dark matter only and non-radiative smooth particle hydrodynamics (SPH) simulations of four massive clusters. The presence of gas-dynamical processes (e.g. ram pressure from the hot intra-cluster atmosphere) makes haloes more fragile in the runs which include gas. This results in a 25 per cent decrease in the total number of subhaloes at z = 0. The impact on the galaxy population predicted by SAMs is complicated by the presence of `orphan' galaxies, i.e. galaxies whose parent substructures are reduced below the resolution limit of the simulation. In the model employed in our study, these galaxies survive (unaffected by the tidal stripping process) for a residual merging time that is computed using a variation of the Chandrasekhar formula. Due to ram-pressure stripping, haloes in gas simulations tend to be less massive than their counterparts in the dark matter simulations. The resulting merging times for satellite galaxies are then longer in these simulations. On the other hand, the presence of gas influences the orbits of haloes making them on average more circular and therefore reducing the estimated merging times with respect to the dark matter only simulation. This effect is particularly significant for the most massive satellites and is (at least in part) responsible for the fact that brightest cluster galaxies in runs with gas have stellar masses which are about 25 per cent larger than those obtained from dark matter only simulations. Our results show that gas dynamics has only a marginal impact on the statistical properties of the galaxy population, but that its impact on the orbits and merging times of haloes strongly influences the assembly of the most massive galaxies.

North American natural gas supply dynamics: A focus on U.S. supply

International Nuclear Information System (INIS)

George, R.

1999-01-01

This paper discusses US natural gas supply dynamics in the context of the North American gas marketplace. Supply fundamentals are examined, methodology is briefly presented, regional supply outlooks are discussed. Assumptions, drivers and issues are highlighted. The analysis and outlook indicate that the sizeable North American resource base can be economically developed to supply growing US natural gas requirements. The major incremental supply sources are likely to come from deepwater Gulf of Mexico, Rocky Mountain regions, onshore Texas and imports from Canada. Given this outlook, major business and investment opportunities exist for the gas upstream and midstream sectors despite some short-term challenges

Vectorization of a Monte Carlo simulation scheme for nonequilibrium gas dynamics

Science.gov (United States)

Boyd, Iain D.

1991-01-01

Significant improvement has been obtained in the numerical performance of a Monte Carlo scheme for the analysis of nonequilibrium gas dynamics through an implementation of the algorithm which takes advantage of vector hardware, as presently demonstrated through application to three different problems. These are (1) a 1D standing-shock wave; (2) the flow of an expanding gas through an axisymmetric nozzle; and (3) the hypersonic flow of Ar gas over a 3D wedge. Problem (3) is illustrative of the greatly increased number of molecules which the simulation may involve, thanks to improved algorithm performance.

Dynamics of a hot (T∼107 K) gas cloud with volume energy losses

International Nuclear Information System (INIS)

Suchkov, A.A.; Berman, V.G.; Mishurov, Yu.N.

1987-01-01

The dynamics of a hot (T=10 6 -5x10 7 K) gas cloud with volume energy losses is investigated by numerical integration of gas dynamics equations. The dynamics is governed by a spherically symmetric gravitational field of the cloud and additional ''hidden'' mass. The cloud mass is taken in the range M 0 =10 10 -10 12 M sun , its radius R 0 =50-200 kpc, the ''hidden'' mass M ν =10 11 -3x10 13 M sun . The results show that in such sytems a structure can develop in the form of a dense compact nucleus with a radius R s 0 , and an extended rarefied hot envelope with a radius R X ∼ R 0 . Among the models involved are those where the gas cloud is either entirely blown up or entirely collapses; in some models, after the phase of initial expansion, part of the gas mass returns back into the system to form a nucleus and an envelope, and the other part leaves the system. The results are discussed in connection with the formation and early evolution of galaxies, the history of star formation and chemical evolution of galaxies, the origin of hot gas in galaxies and clusters of galaxies. It is suggested that in the real history of galaxies, formation of the nucleus and envelope corresponds to formation of galactic stellar component and X-ray halo

Hemodynamics and Gas Exchange Effects of Inhaled Nitrous Oxide in Patients with Acute Respiratory Distress Syndrome

Directory of Open Access Journals (Sweden)

V. N. Poptsov

2006-01-01

Full Text Available Inhaled nitrous oxide (iNO therapy aimed at improving pulmonary oxygenizing function and at decreasing artificial ventilation (AV load has been used in foreign clinical practice in the past decade. The study was undertaken to evaluate the hemodynamic and gas exchange effects of iNO in acute respiratory distress syndrome (ARDS that developed after car-diosurgical operations. Fifty-eight (43 males and 15 females patients aged 21 to 76 (55.2±2.4 years were examined. The study has demonstrated that in 48.3% of cases, the early stage of ARDS is attended by the increased tone pulmonary vessels due to impaired NO-dependent vasodilatation. In these patients, iNO therapy is an effective therapeutic method for correcting hemodynamic disorders and lung oxygenizing function.

DYNAMICAL EVOLUTION OF AGN HOST GALAXIES-GAS IN/OUT-FLOW RATES IN SEVEN NUGA GALAXIES

International Nuclear Information System (INIS)

Haan, Sebastian; Schinnerer, Eva; Rix, Hans-Walter; Emsellem, Eric; GarcIa-Burillo, Santiago; Combes, Francoise; Mundell, Carole G.

2009-01-01

To examine the role of the host galaxy structure in fueling nuclear activity, we estimated gas flow rates from several kpc down to the inner few 10 pc for seven nearby spiral galaxies, selected from the NUclei of GAlaxies sample. We calculated gravitational torques from near-infrared images and determined gas in/out-flow rates as a function of radius and location within the galactic disks, based on high angular resolution interferometric observations of molecular (CO using Plateau de Bure interferometer) and atomic (H I using the Very Large Array) gas. The results are compared with kinematic evidence for radial gas flows and the dynamical state of the galaxies (via resonances) derived from several different methods. We show that gravitational torques are very efficient at transporting gas from the outer disk all the way into the galaxies centers at ∼100 pc; previously assumed dynamical barriers to gas transport, such as the corotation resonance of stellar bars, seem to be overcome by gravitational torque induced gas flows from other nonaxisymmetric structures. The resulting rates of gas mass inflow range from 0.01 to 50 M sun yr -1 and are larger for the galaxy center than for the outer disk. Our gas flow maps show the action of nested bars within larger bars for three galaxies. Noncircular streaming motions found in the kinematic maps are larger in the center than in the outer disk and appear to correlate only loosely with the in/out-flow rates as a function of radius. We demonstrate that spiral gas disks are very dynamic systems that undergo strong radial evolution on timescales of a few rotation periods (e.g., 5 x 10 8 yrs at a radius of 5 kpc), due to the effectiveness of gravitational torques in redistributing the cold galactic gas.

Bifurcation and nonlinear dynamic analysis of a flexible rotor supported by relative short gas journal bearings

International Nuclear Information System (INIS)

Wang, C.-C.; Jang, M.-J.; Yeh, Y.-L.

2007-01-01

This paper studies the bifurcation and nonlinear behaviors of a flexible rotor supported by relative short gas film bearings. A time-dependent mathematical model for gas journal bearings is presented. The finite difference method with successive over relation method is employed to solve the Reynolds' equation. The system state trajectory, Poincare maps, power spectra, and bifurcation diagrams are used to analyze the dynamic behavior of the rotor and journal center in the horizontal and vertical directions under different operating conditions. The analysis reveals a complex dynamic behavior comprising periodic and subharmonic response of the rotor and journal center. This paper shows how the dynamic behavior of this type of system varies with changes in rotor mass and rotational velocity. The results of this study contribute to a further understanding of the nonlinear dynamics of gas film rotor-bearing systems

Use of dynamic CT in acute respiratory distress syndrome (ARDS) with comparison of positive and negative pressure ventilation

Energy Technology Data Exchange (ETDEWEB)

Helm, Emma; Babyn, Paul [Hospital for Sick Children, Department of Diagnostic Imaging, Toronto (Canada); Talakoub, Omid; Alirezaie, Javad [Ryerson University, Department of Electrical and Computer Engineering, Toronto, ON (Canada); Grasso, Francesco; Engelberts, Doreen; Kavanagh, Brian P. [Hospital for Sick Children and the University of Toronto, Departments of Anesthesia and Critical Care Medicine and the Program in Pulmonary and Experimental Medicine, Toronto (Canada)

2009-01-15

Negative pressure ventilation via an external device ('iron lung') has the potential to provide better oxygenation with reduced barotrauma in patients with ARDS. This study was designed to see if oxygenation differences between positive and negative ventilation could be explained by CT. Six anaesthetized rabbits had ARDS induced by repeated saline lavage. Rabbits were ventilated with positive pressure ventilation (PPV) and negative pressure ventilation (NPV) in turn. Dynamic CT images were acquired over the respiratory cycle. A computer-aided method was used to segment the lung and calculate the range of CT densities within each slice. Volumes of ventilated lung and atelectatic lung were measured over the respiratory cycle. NPV was associated with an increased percentage of ventilated lung and decreased percentage of atelectatic lung. The most significant differences in ventilation and atelectasis were seen at mid-inspiration and mid-expiration (ventilated lung NPV=61%, ventilated lung PPV=47%, p<0.001; atelectatic lung NPV=10%, atelectatic lung PPV 19%, p<0.001). Aeration differences were not significant at end-inspiration. Dynamic CT can show differences in lung aeration between positive and negative ventilation in ARDS. These differences would not be appreciated if only static breath-hold CT was used. (orig.)

Study on the dynamics of charged particles in a rarefied gas of thermonuclear reactor injector

International Nuclear Information System (INIS)

Afanas'ev, P.N.; Svistunov, Yu.A.; Sidorov, V.P.; Udovichenko, S.Yu.

1987-01-01

The motion of an ion beam directly beyond the source is considered in the assumption of homogeneous density of rarefied gas along the injector. Using numerical simulation the dynamics of fast particles in plasma electric field, created by the beam as a result of gas neutral atom ionization, is investigated. It is shown that stationary ambipolar electric field of ''plasma lens'' can affect considerably the beam transverse dynamics

The dynamics of the world gas trade

International Nuclear Information System (INIS)

Chabrelie, M.F.

2003-01-01

The steadily growing distances between the world's gas rich regions and consumer zones foreshadow a powerful expansion of the international trade, at an annual rate of around 3.5% by 2020. Flows could then account for about 32% of marketed production. Trade by LNG tanker is very likely to emerge as the winner of this dynamic, with the flexibility it procures exploited to adjust supply to the demand of a more global market. This is today's gamble of an industry which, driven by technological improvements and market potential, is investing massively in new infrastructures

Can we Replace Arterial Blood Gas Analysis by Pulse Oximetry in Neonates with Respiratory Distress Syndrome, who are Treated According to INSURE Protocol?

Directory of Open Access Journals (Sweden)

Pedram Niknafs

2015-05-01

Full Text Available Neonates with respiratory distress syndrome (RDS, who are treated according to INSURE protocol; require arterial blood gas (ABG analysis to decide on appropriate management. We conducted this study to investigate the validity of pulse oximetry instead of frequent ABG analysis in the evaluation of these patients. From a total of 193 blood samples obtained from 30 neonates <1500 grams with RDS, 7.2% were found to have one or more of the followings: acidosis, hypercapnia, or hypoxemia. We found that pulse oximetry in the detection of hyperoxemia had a good validity to appropriately manage patients without blood gas analysis. However, the validity of pulse oximetry was not good enough to detect acidosis, hypercapnia, and hypoxemia.

High resolution kinetic beam schemes in generalized coordinates for ideal quantum gas dynamics

International Nuclear Information System (INIS)

Shi, Yu-Hsin; Huang, J.C.; Yang, J.Y.

2007-01-01

A class of high resolution kinetic beam schemes in multiple space dimensions in general coordinates system for the ideal quantum gas is presented for the computation of quantum gas dynamical flows. The kinetic Boltzmann equation approach is adopted and the local equilibrium quantum statistics distribution is assumed. High-order accurate methods using essentially non-oscillatory interpolation concept are constructed. Computations of shock wave diffraction by a circular cylinder in an ideal quantum gas are conducted to illustrate the present method. The present method provides a viable means to explore various practical ideal quantum gas flows

Dynamical evolution of stars and gas of young embedded stellar sub-clusters

Science.gov (United States)

Sills, Alison; Rieder, Steven; Scora, Jennifer; McCloskey, Jessica; Jaffa, Sarah

2018-03-01

We present simulations of the dynamical evolution of young embedded star clusters. Our initial conditions are directly derived from X-ray, infrared, and radio observations of local systems, and our models evolve both gas and stars simultaneously. Our regions begin with both clustered and extended distributions of stars, and a gas distribution which can include a filamentary structure in addition to gas surrounding the stellar subclusters. We find that the regions become spherical, monolithic, and smooth quite quickly, and that the dynamical evolution is dominated by the gravitational interactions between the stars. In the absence of stellar feedback, the gas moves gently out of the centre of our regions but does not have a significant impact on the motions of the stars at the earliest stages of cluster formation. Our models at later times are consistent with observations of similar regions in the local neighbourhood. We conclude that the evolution of young proto-star clusters is relatively insensitive to reasonable choices of initial conditions. Models with more realism, such as an initial population of binary and multiple stars and ongoing star formation, are the next step needed to confirm these findings.

High temperature gas dynamics an introduction for physicists and engineers

CERN Document Server

Bose, Tarit K

2014-01-01

High Temperature Gas Dynamics is a primer for scientists, engineers, and students who would like to have a basic understanding of the physics and the behavior of high-temperature gases. It is a valuable tool for astrophysicists as well. The first chapters treat the basic principles of quantum and statistical mechanics and how to derive thermophysical properties from them. Special topics are included that are rarely found in other textbooks, such as the thermophysical and transport properties of multi-temperature gases and a novel method to compute radiative transfer. Furthermore, collision processes between different particles are discussed. Separate chapters deal with the production of high-temperature gases and with electrical emission in plasmas, as well as related diagnostic techniques.This new edition adds over 100 pages and includes the following updates: several sections on radiative properties of high temperature gases and various radiation models, a section on shocks in magneto-gas-dynamics, a sectio...

Impacts of ocean acidification on respiratory gas exchange and acid-base balance in a marine teleost, Opsanus beta.

Science.gov (United States)

Esbaugh, Andrew J; Heuer, Rachael; Grosell, Martin

2012-10-01

The oceanic carbonate system is changing rapidly due to rising atmospheric CO(2), with current levels expected to rise to between 750 and 1,000 μatm by 2100, and over 1,900 μatm by year 2300. The effects of elevated CO(2) on marine calcifying organisms have been extensively studied; however, effects of imminent CO(2) levels on teleost acid-base and respiratory physiology have yet to be examined. Examination of these physiological processes, using a paired experimental design, showed that 24 h exposure to 1,000 and 1,900 μatm CO(2) resulted in a characteristic compensated respiratory acidosis response in the gulf toadfish (Opsanus beta). Time course experiments showed the onset of acidosis occurred after 15 min of exposure to 1,900 and 1,000 μatm CO(2), with full compensation by 2 and 4 h, respectively. 1,900-μatm exposure also resulted in significantly increased intracellular white muscle pH after 24 h. No effect of 1,900 μatm was observed on branchial acid flux; however, exposure to hypercapnia and HCO(3)(-) free seawater compromised compensation. This suggests branchial HCO(3)(-) uptake rather than acid extrusion is part of the compensatory response to low-level hypercapnia. Exposure to 1,900 μatm resulted in downregulation in branchial carbonic anhydrase and slc4a2 expression, as well as decreased Na(+)/K(+) ATPase activity after 24 h of exposure. Infusion of bovine carbonic anhydrase had no effect on blood acid-base status during 1,900 μatm exposures, but eliminated the respiratory impacts of 1,000 μatm CO(2). The results of the current study clearly show that predicted near-future CO(2) levels impact respiratory gas transport and acid-base balance. While the full physiological impacts of increased blood HCO(3)(-) are not known, it seems likely that chronically elevated blood HCO(3)(-) levels could compromise several physiological systems and furthermore may explain recent reports of increased otolith growth during exposure to elevated CO(2).

Transient hypoxic respiratory failure in a patient with severe hypophosphatemia.

Science.gov (United States)

Oud, Lavi

2009-03-01

Respiratory failure in severely hypophosphatemic patients has been attributed to respiratory muscle weakness, leading to ventilatory failure. While frequently documenting hypercarbic respiratory failure, previous reports of hypophosphatemia-related respiratory failure in patients otherwise free of pulmonary or airway disease often did not provide sufficient information on gas exchange and pulmonary function, precluding inference on alternative or additional sources of respiratory dysfunction in this population. We report a case of acute hypoxic respiratory failure in a 26 year-old bulimic woman with severe hypophosphatemia. The patient presented with acute onset of dyspnea, paresthesias, limb shaking, and severe hyperventilation. SpO2 was 74%, requiring administration of 100% O2, with normal chest radiograph. Serum phosphate was <0.3 mmol/liter (1.0 mg/dL). Further evaluation did not support pulmonary, vascular, neurogenic or external exposure-related causes of hypoxic respiratory failure, which rapidly resolved with parenteral correction of hypophosphatemia. To date, hypoxic respiratory failure has not been reported in association with hypophosphatemia. Increased awareness and further investigations can help elucidate the mechanisms of hypophosphatemia-associated hypoxemia.

Flow-pattern identification and nonlinear dynamics of gas-liquid two-phase flow in complex networks.

Science.gov (United States)

Gao, Zhongke; Jin, Ningde

2009-06-01

The identification of flow pattern is a basic and important issue in multiphase systems. Because of the complexity of phase interaction in gas-liquid two-phase flow, it is difficult to discern its flow pattern objectively. In this paper, we make a systematic study on the vertical upward gas-liquid two-phase flow using complex network. Three unique network construction methods are proposed to build three types of networks, i.e., flow pattern complex network (FPCN), fluid dynamic complex network (FDCN), and fluid structure complex network (FSCN). Through detecting the community structure of FPCN by the community-detection algorithm based on K -mean clustering, useful and interesting results are found which can be used for identifying five vertical upward gas-liquid two-phase flow patterns. To investigate the dynamic characteristics of gas-liquid two-phase flow, we construct 50 FDCNs under different flow conditions, and find that the power-law exponent and the network information entropy, which are sensitive to the flow pattern transition, can both characterize the nonlinear dynamics of gas-liquid two-phase flow. Furthermore, we construct FSCN and demonstrate how network statistic can be used to reveal the fluid structure of gas-liquid two-phase flow. In this paper, from a different perspective, we not only introduce complex network theory to the study of gas-liquid two-phase flow but also indicate that complex network may be a powerful tool for exploring nonlinear time series in practice.

Respiratory guiding system for respiratory motion management in respiratory gated radiotherapy

International Nuclear Information System (INIS)

Kang, Seong Hee; Kim, Dong Su; Kim, Tae Ho; Suh, Tae Suk

2013-01-01

Respiratory guiding systems have been shown to improve the respiratory regularity. This, in turn, improves the efficiency of synchronized moving aperture radiation therapy, and it reduces the artifacts caused by irregular breathing in imaging techniques such as four-dimensional computed tomography (4D CT), which is used for treatment planning in RGRT. We have previously developed a respiratory guiding system that incorporates an individual-specific guiding waveform, which is easy to follow for each volunteer, to improve the respiratory regularity. The present study evaluates the application of this system to improve the respiratory regularity for respiratory-gated radiation therapy (RGRT). In this study, we evaluated the effectiveness of an in-house-developed respiratory guiding system incorporating an individual specific guiding waveform to improve the respiratory regularity for RGRT. Most volunteers showed significantly less residual motion at each phase during guided breathing owing to the improvement in respiratory regularity. Therefore, the respiratory guiding system can clearly reduce the residual, or respiratory, motion in each phase. From the result, the CTV and the PTV margins during RGRT can be reduced by using the respiratory guiding system, which reduces the residual motions, thus improving the accuracy of RGRT

Fluctuations and Noise in Stochastic Spread of Respiratory Infection Epidemics in Social Networks

Science.gov (United States)

Yulmetyev, Renat; Emelyanova, Natalya; Demin, Sergey; Gafarov, Fail; Hänggi, Peter; Yulmetyeva, Dinara

2003-05-01

For the analysis of epidemic and disease dynamics complexity, it is necessary to understand the basic principles and notions of its spreading in long-time memory media. Here we considering the problem from a theoretical and practical viewpoint, presenting the quantitative evidence confirming the existence of stochastic long-range memory and robust chaos in a real time series of respiratory infections of human upper respiratory track. In this work we present a new statistical method of analyzing the spread of grippe and acute respiratory track infections epidemic process of human upper respiratory track by means of the theory of discrete non-Markov stochastic processes. We use the results of our recent theory (Phys. Rev. E 65, 046107 (2002)) for the study of statistical effects of memory in real data series, describing the epidemic dynamics of human acute respiratory track infections and grippe. The obtained results testify to an opportunity of the strict quantitative description of the regular and stochastic components in epidemic dynamics of social networks with a view to time discreteness and effects of statistical memory.

Type 2 diabetes affects sleep quality by disrupting the respiratory function.

Science.gov (United States)

Colbay, Gulcan; Cetin, Mustafa; Colbay, Mehmet; Berker, Dilek; Guler, Serdar

2015-09-01

The effects of diabetes on the respiratory system were investigated with arterial blood gas, sleep quality index and respiratory functions tests. Fifty-three patients with type II diabetes and 41 healthy cases were included. Their biochemical data, demographic characteristics, anthropometric measurements and echocardiographic findings were collected from polyclinic records. Respiratory function tests were performed for all subjects and Pittsburgh Sleep Quality Index questionnaire was conducted. Aforementioned data were compared between these two groups. The age, body weight and body mass index were similar but oxygen pressure, oxygen saturation, forced vital capacity (FVC; %), and sleep quality were decreased in patients with diabetes. Sleep quality was correlated with the presence of diabetes and hypertension, duration of diabetes, fasting and postprandial blood glucose levels, homeostasis model of assessment-insulin resistance, Glycosylated hemoglobin levels, and FVC. Half of the diabetic patients exhibited respiratory failure during sleep. Especially diabetic patients with autonomic neuropathy, experienced a more severe and prolonged decrease in oxygen saturation. Blood gas, respiratory functions and sleep quality, which need to be evaluated as a whole, were affected in patients with diabetes. Assessment of sleep and its quality requires special attention in patients with diabetes. © 2014 Ruijin Hospital, Shanghai Jiaotong University School of Medicine and Wiley Publishing Asia Pty Ltd.

Gas phase collision dynamics by means of pulse-radiolysis methods

International Nuclear Information System (INIS)

Hatano, Yoshihiko

1989-01-01

After a brief survey of recent advances in gas-phase collision dynamics studies using pulse radiolysis methods, the following two topics in our research programs are presented with emphasis on the superior advantages of the pulse radiolysis methods over the various methods of gas-phase collision dynamics, such as beam methods, swarm methods and flow methods. One of the topics is electron attachment to van der Waals molecules. The attachment rates of thermal electrons to O 2 and other molecules in dense gases have been measured in wide ranges of both gas temperatures and pressures, from which experimental evidence has been obtained for electron attachment to van der Waals molecules. The results have been compared with theories and discussed in terms of the effect of van der Waals interaction on the electron attachment resonance. The obtained conclusions have been related with investigations of electron attachment, solvation and localization in the condensed phase. The other is Penning ionization and its related processes. The rate constants for the de-excitation of He(2 1 P), He(2 3 S), Ne( 3 P 0 ), Ne( 3 P 1 ), Ne( 3 P 2 ), Ar( 1 P 1 ), Ar( 3 P 1 ), by atoms and molecules have been measured in the temperature range from 100 to 300 K, thus obtaining the collisional energy dependence of the de-excitation cross sections. The results are compared in detail with theories classified according to the excited rare gas atoms in the metastable and resonance states. (author)

The Characteristics of Middle Eastern Respiratory Syndrome Coronavirus Transmission Dynamics in South Korea.

Science.gov (United States)

Kim, Yunhwan; Lee, Sunmi; Chu, Chaeshin; Choe, Seoyun; Hong, Saeme; Shin, Youngseo

2016-02-01

The outbreak of Middle Eastern respiratory syndrome coronavirus (MERS-CoV) was one of the major events in South Korea in 2015. In particular, this study pays attention to formulating a mathematical model for MERS transmission dynamics and estimating transmission rates. Incidence data of MERS-CoV from the government authority was analyzed for the first aim and a mathematical model was built and analyzed for the second aim of the study. A mathematical model for MERS-CoV transmission dynamics is used to estimate the transmission rates in two periods due to the implementation of intensive interventions. Using the estimates of the transmission rates, the basic reproduction number was estimated in two periods. Due to the superspreader, the basic reproduction number was very large in the first period; however, the basic reproduction number of the second period has reduced significantly after intensive interventions. It turned out to be the intensive isolation and quarantine interventions that were the most critical factors that prevented the spread of the MERS outbreak. The results are expected to be useful to devise more efficient intervention strategies in the future.

Application of advanced data reduction methods to gas turbine dynamic analysis

International Nuclear Information System (INIS)

Juhl, P.B.

1978-01-01

This paper discusses the application of advanced data reduction methods to the evaluation of dynamic data from gas turbines and turbine components. The use of the Fast Fourier Transform and of real-time spectrum analyzers is discussed. The use of power spectral density and probability density functions for analyzing random data is discussed. Examples of the application of these modern techniques to gas turbine testing are presented. The use of the computer to automate the data reduction procedures is discussed. (orig.) [de

Exhaust Gas Temperature Measurements in Diagnostics of Turbocharged Marine Internal Combustion Engines Part II Dynamic Measurements

Directory of Open Access Journals (Sweden)

Korczewski Zbigniew

2016-01-01

Full Text Available The second part of the article describes the technology of marine engine diagnostics making use of dynamic measurements of the exhaust gas temperature. Little-known achievements of Prof. S. Rutkowski of the Naval College in Gdynia (now: Polish Naval Academy in this area are presented. A novel approach is proposed which consists in the use of the measured exhaust gas temperature dynamics for qualitative and quantitative assessment of the enthalpy flux of successive pressure pulses of the exhaust gas supplying the marine engine turbocompressor. General design assumptions are presented for the measuring and diagnostic system which makes use of a sheathed thermocouple installed in the engine exhaust gas manifold. The corrected thermal inertia of the thermocouple enables to reproduce a real time-history of exhaust gas temperature changes.

A gas dynamic and thermochemical model of steam/sodium microleak phenomena

International Nuclear Information System (INIS)

Perkins, R.; Airey, R.; Daniels, L.C.

1985-06-01

Conflicting findings have been reported by 3 UK laboratories for the blockage or rapid escalation of steam/sodium microleaks. In an earlier paper it was shown that this discrepancy could be resolved through the influence on the steam flow of the geometry of the leak paths; the geometry being dependent upon the method of manufacture. The application of gas dynamics and thermochemical methods could account for the rapid escalation of some leaks in terms of the presence of shock waves in the gas flow within the leak path. In this paper the gas dynamic and thermochemical theories are re-stated and a series of leak experiments conducted to test the validity of the theory is described. The theory predicts that for some leaks of variable area of cross-section the blockage/escalation behaviour is determined by small changes in the sodium-side pressure; this effect was found and is discussed as a validation of the theory. Other aspects of leak phenomena are discussed and conclusions are drawn with emphasis on implications for further programmes of leak study and for leaks in LMFBR steam generators in service. (author)

Dynamic gas flow during plasma operation in TMX-U

International Nuclear Information System (INIS)

Pickles, W.L.; Carter, M.R.; Clower, C.A.; Drake, R.P.; Hunt, A.L.; Simonen, T.C.; Turner, W.C.

1982-01-01

Control of the neutral density outside of the plasma radius is essential for proper operation of the various plasma configurations in TMX-U. TMX-U excess-beam, stream-gun, gas-box, and beam-reflux gases are pumped internally in regions defined by 73 0 Ti-gettered liners and warm Ti-gettered plasma liners. The array of fast and slow ion gauges - a large TMX-U diagnostic - has been used to measure the dynamic pressure in many of the liner-defined regions on three time scales. The natural divertor action, or plasma pump effect, of mirror plasmas has been measured using the ion gauge diagnostics on a fast time scale during operation of TMX-U with ECRH start-up. Routine operation of TMX-U is enhanced by the ability to verify the effectiveness of gettering and to locate leaks using pressure data collected on the two slow time scales. A computer code, DYNAVAC 6, which treats TMX-U as a set of conductance-coupled regions with pumping and sources in each region, has been used to successfully model the overall gas dynamics during all phases of TMX-U operation

Dynamic Regression Model for Evaluating the Association Between Atmospheric Conditions and Deaths due to Respiratory Diseases in São Paulo, Brazil

Directory of Open Access Journals (Sweden)

Ana Carla dos Santos Gomes

Full Text Available Abstract The article reports the modeling of mortality due to respiratory diseases emanating from atmospheric conditions, capturing significant associations and verifying the ability of stochastic modeling to predict deaths arising from the relationship between weather conditions and air pollution. The statistical methods used in the analysis were cross-correlation and pre-whitening, in addition to dynamic regression modeling combining the dynamics of time series and the effect of explanatory variables. The results show there are significant associations between mortality and sulfur dioxide, air temperature, atmospheric pressure, relative humidity, and autoregressive structure. The cross-correlations captured significant lags between atmospheric variables and deaths, of two months for SO2 and relative humidity, eleven months for PM10, seven months for O3, and eight months for air temperature and the cross-correlation without lag with NO2. With CO variables, precipitation and atmospheric pressure, cross-correlations were not detected. Stochastic modeling showed that deaths due to respiratory diseases can be predicted from the combination of meteorological and air pollution variables, especially considering the existing trend and seasonality.

CFD heat transfer simulation of the human upper respiratory tract for oronasal breathing condition

Directory of Open Access Journals (Sweden)

Kambiz Farahmand

2012-01-01

Full Text Available Injuries due to inhalation of hot gas are commonly encountered when dealing with fire and combustible material, which is harmful and threatens human life. In the literature, various studies have been conducted to investigate heat and mass transfer characteristics in the human respiratory tract (HRT. This study focuses on assessing the injury taking place in the upper human respiratory tract and identifying acute tissue damage, based on level of exposure. A three-dimensional heat transfer simulation is performed using Computational Fluid Dynamics (CFD software to study the temperature profile through the upper HRT consisting of the nasal cavity, oral cavity, trachea, and the first two generations of bronchi. The model developed is for the simultaneous oronasal breathing during the inspiration phase with a high volumetric flow rate of 90 liters/minute and the inspired air temperature of 100 degrees Celsius. The geometric model depicting the upper HRT is generated based on the data available and literature cited. The results of the simulation give the temperature distribution along the center and the surface tissue of the respiratory tract. This temperature distribution will help to assess the level of damage induced in the upper respiratory tract and appropriate treatment for the damage. A comparison of nasal breathing, oral breathing, and oronasal breathing is performed. Temperature distribution can be utilized in the design of the respirator systems where inlet temperature is regulated favoring the human body conditions.

Dynamic design of gas sorption J-T refrigerator

International Nuclear Information System (INIS)

Chan, C.K.

1986-01-01

A long-life Joule-Thomson refrigerator which is heat powered, involves no sealing, and has few mechanical parts and is desirable for longterm sensor cooling in space. In the gas-sorption J-T refrigerator, cooling is achieved by gas sorption (either adsorption or absorption) processes. Currently, a modular, single-stage refrigerator is being designed and built to be operated at 20 K. The design was analyzed using a dynamic model, which is described here. The model includes the kinetics of the compressors and the heat switches, the heat transfer of the pre-coolers and the heat exchangers, the on/off ratio of the check valves, and the impedance of the J-T valve. The cooling power, the cycle time, and the operating conditions were obtained in terms of the power input, the heat sink temperature, and the J-T impedance

Dynamic design of gas sorption J-T refrigerator

Science.gov (United States)

Chan, C. K.

1986-01-01

A long-life Joule-Thomson refrigerator which is heat powered, involves no sealing, and has few mechanical parts is desirable for long-term sensor cooling in space. In the gas-sorption J-T refrigerator, cooling is achieved by gas sorption (either adsorption or absorption) processes. Currently, a modular, single-stage refrigerator is being designed and built to be operated at 20 K. The design was analyzed using a dynamic model, which is described here. The model includes the kinetics of the compressors and the heat switches, the heat transfer of the pre-coolers and the heat exchangers, the on/off ratio of the check valves, and the impedance of the J-T valve. The cooling power, the cycle time, and the operating conditions were obtained in terms of the power input, the heat sink temperature, and the J-T impedance.

Respiratory function in the prune-belly syndrome.

OpenAIRE

Crompton, C H; MacLusky, I B; Geary, D F

1993-01-01

Respiratory function was evaluated in 11 patients with prune-belly syndrome. Nine had evidence of gas trapping and six of restrictive lung disease. These abnormalities of lung function appear to be secondary to the musculoskeletal disorder associated with prune-belly syndrome rather than parenchymal lung disease.

Dynamic modeling of gas turbines in integrated gasification fuel cell systems

Science.gov (United States)

Maclay, James Davenport

2009-12-01

Solid oxide fuel cell-gas turbine (SOFC-GT) hybrid systems for use in integrated gasification fuel cell (IGFC) systems operating on coal will stretch existing fossil fuel reserves, generate power with less environmental impact, while having a cost of electricity advantage over most competing technologies. However, the dynamic performance of a SOFC-GT in IGFC applications has not been previously studied in detail. Of particular importance is how the turbo-machinery will be designed, controlled and operated in such applications; this is the focus of the current work. Perturbation and dynamic response analyses using numerical SimulinkRTM models indicate that compressor surge is the predominant concern for safe dynamic turbo-machinery operation while shaft over-speed and excessive turbine inlet temperatures are secondary concerns. Fuel cell temperature gradients and anode-cathode differential pressures were found to be the greatest concerns for safe dynamic fuel cell operation. Two control strategies were compared, that of constant gas turbine shaft speed and constant fuel cell temperature, utilizing a variable speed gas turbine. Neither control strategy could eliminate all vulnerabilities during dynamic operation. Constant fuel cell temperature control ensures safe fuel cell operation, while constant speed control does not. However, compressor surge is more likely with constant fuel cell temperature control than with constant speed control. Design strategies that provide greater surge margin while utilizing constant fuel cell temperature control include increasing turbine design mass flow and decreasing turbine design inlet pressure, increasing compressor design pressure ratio and decreasing compressor design mass flow, decreasing plenum volume, decreasing shaft moment of inertia, decreasing fuel cell pressure drop, maintaining constant compressor inlet air temperature. However, these strategies in some cases incur an efficiency penalty. A broad comparison of cycles

Impact of respiratory motion correction and spatial resolution on lesion detection in PET: a simulation study based on real MR dynamic data

Science.gov (United States)

Polycarpou, Irene; Tsoumpas, Charalampos; King, Andrew P.; Marsden, Paul K.

2014-02-01

The aim of this study is to investigate the impact of respiratory motion correction and spatial resolution on lesion detectability in PET as a function of lesion size and tracer uptake. Real respiratory signals describing different breathing types are combined with a motion model formed from real dynamic MR data to simulate multiple dynamic PET datasets acquired from a continuously moving subject. Lung and liver lesions were simulated with diameters ranging from 6 to 12 mm and lesion to background ratio ranging from 3:1 to 6:1. Projection data for 6 and 3 mm PET scanner resolution were generated using analytic simulations and reconstructed without and with motion correction. Motion correction was achieved using motion compensated image reconstruction. The detectability performance was quantified by a receiver operating characteristic (ROC) analysis obtained using a channelized Hotelling observer and the area under the ROC curve (AUC) was calculated as the figure of merit. The results indicate that respiratory motion limits the detectability of lung and liver lesions, depending on the variation of the breathing cycle length and amplitude. Patients with large quiescent periods had a greater AUC than patients with regular breathing cycles and patients with long-term variability in respiratory cycle or higher motion amplitude. In addition, small (less than 10 mm diameter) or low contrast (3:1) lesions showed the greatest improvement in AUC as a result of applying motion correction. In particular, after applying motion correction the AUC is improved by up to 42% with current PET resolution (i.e. 6 mm) and up to 51% for higher PET resolution (i.e. 3 mm). Finally, the benefit of increasing the scanner resolution is small unless motion correction is applied. This investigation indicates high impact of respiratory motion correction on lesion detectability in PET and highlights the importance of motion correction in order to benefit from the increased resolution of future

Impact of respiratory motion correction and spatial resolution on lesion detection in PET: a simulation study based on real MR dynamic data

International Nuclear Information System (INIS)

Polycarpou, Irene; Tsoumpas, Charalampos; King, Andrew P; Marsden, Paul K

2014-01-01

The aim of this study is to investigate the impact of respiratory motion correction and spatial resolution on lesion detectability in PET as a function of lesion size and tracer uptake. Real respiratory signals describing different breathing types are combined with a motion model formed from real dynamic MR data to simulate multiple dynamic PET datasets acquired from a continuously moving subject. Lung and liver lesions were simulated with diameters ranging from 6 to 12 mm and lesion to background ratio ranging from 3:1 to 6:1. Projection data for 6 and 3 mm PET scanner resolution were generated using analytic simulations and reconstructed without and with motion correction. Motion correction was achieved using motion compensated image reconstruction. The detectability performance was quantified by a receiver operating characteristic (ROC) analysis obtained using a channelized Hotelling observer and the area under the ROC curve (AUC) was calculated as the figure of merit. The results indicate that respiratory motion limits the detectability of lung and liver lesions, depending on the variation of the breathing cycle length and amplitude. Patients with large quiescent periods had a greater AUC than patients with regular breathing cycles and patients with long-term variability in respiratory cycle or higher motion amplitude. In addition, small (less than 10 mm diameter) or low contrast (3:1) lesions showed the greatest improvement in AUC as a result of applying motion correction. In particular, after applying motion correction the AUC is improved by up to 42% with current PET resolution (i.e. 6 mm) and up to 51% for higher PET resolution (i.e. 3 mm). Finally, the benefit of increasing the scanner resolution is small unless motion correction is applied. This investigation indicates high impact of respiratory motion correction on lesion detectability in PET and highlights the importance of motion correction in order to benefit from the increased resolution of future

MULTI-CRITERIA EVALUATION OF THE EXPANSION OF NATURAL GAS DISTRIBUTION NETWORK BY THE URBAN DYNAMICS

Directory of Open Access Journals (Sweden)

Vanessa M. Massara

2010-01-01

Full Text Available The objective of this work is to analyze the expansion of the infrastructure of natural gas distribution, identifying priorities from large metropolis using the energy planning based on urban design tools like urban dynamics and techniques like AHP (analytic hierarchy process. The methodology proposed uses matrices considering the relations between the concept of urban dynamics, quality of life and the possibilities of natural gas displacing other energy forms. The matrices are made up of information about social and urban development, costs of establishing the infrastructure and projections of the consumption potential in various sectors. Relating the consumption to urban development parameters and the real estate future of the areas in study, the methodology allows indicating for each district, the viability of implementing a gas network. As conclusion, the model presents the integration between the cities profile and the natural gas use, by means of a growth natural gas on districts of São Paulo City as a specific case study.

A new technique in constructing closed-form solutions for nonlinear PDEs appearing in fluid mechanics and gas dynamics

Directory of Open Access Journals (Sweden)

Panayotounakos D. E.

1996-01-01

Full Text Available We develop a new unique technique in constructing closed-form solutions for several nonlinear partial differential systems appearing in fluid mechanics and gas dynamics. The obtained solutions include fewer arbitrary functions than needed for general solutions, fact that permits us to specify them according to the initial state, or the geometry, of each specific problem under consideration. In order to apply the before mentioned technique we construct closed-form solutions concerning the gas-dynamic equations with constant pressure, the dynamic equations of an ideal gas in isentropic flow, and the two-dimensional incompressible boundary layer flow.

REM sleep estimation only using respiratory dynamics

International Nuclear Information System (INIS)

Chung, Gih Sung; Choi, Byung Hoon; Lee, Jeong Su; Lee, Jin-Seong; Jeong, Do-Un; Park, Kwang Suk

2009-01-01

Polysomnography (PSG) is currently considered the gold standard for assessing sleep quality. However, the numerous sensors that must be attached to the subject can disturb sleep and limit monitoring to within hospitals and sleep clinics. If data could be obtained without such constraints, sleep monitoring would be more convenient and could be extended to ordinary homes. During rapid-eye-movement (REM) sleep, respiration rate and variability are known to be greater than in other sleep stages. Hence, we calculated the average rate and variability of respiration in an epoch (30 s) by applying appropriate smoothing algorithms. Increased and irregular respiratory patterns during REM sleep were extracted using adaptive and linear thresholds. When both parameters simultaneously showed higher values than the thresholds, the epochs were assumed to belong to REM sleep. Thermocouples and piezoelectric-type belts were used to acquire respiratory signals. Thirteen healthy adults and nine obstructive sleep apnea (OSA) patients participated in this study. Kappa statistics showed a substantial agreement (κ > 0.60) between the standard and respiration-based methods. One-way ANOVA analysis showed no significant difference between the techniques for total REM sleep. This approach can also be applied to the non-intrusive measurement of respiration signals, making it possible to automatically detect REM sleep without disturbing the subject

Dynamic Optimal Energy Flow in the Integrated Natural Gas and Electrical Power Systems

DEFF Research Database (Denmark)

Fang, Jiakun; Zeng, Qing; Ai, Xiaomeng

2018-01-01

. Simulation on the test case illustrates the success of the modelling and the beneficial roles of the power-to-gas are analyzed. The proposed model can be used in the decision support for both planning and operation of the coordinated natural gas and electrical power systems.......This work focuses on the optimal operation of the integrated gas and electrical power system with bi-directional energy conversion. Considering the different response times of the gas and power systems, the transient gas flow and steady- state power flow are combined to formulate the dynamic...... optimal energy flow in the integrated gas and power systems. With proper assumptions and simplifications, the problem is transformed into a single stage linear programming. And only a single stage linear programming is needed to obtain the optimal operation strategy for both gas and power systems...

Respiratory function in the prune-belly syndrome.

Science.gov (United States)

Crompton, C H; MacLusky, I B; Geary, D F

1993-01-01

Respiratory function was evaluated in 11 patients with prune-belly syndrome. Nine had evidence of gas trapping and six of restrictive lung disease. These abnormalities of lung function appear to be secondary to the musculoskeletal disorder associated with prune-belly syndrome rather than parenchymal lung disease. PMID:8503677

Gas Exchange and Mechanical Properties of the Lung in Miners with Severe Concomitant Injury

Directory of Open Access Journals (Sweden)

V. V. Moroz

2007-01-01

Full Text Available Objective: to study the specific features of pulmonary gas exchange and mechanical properties in various manifestations of respiratory failure in miners with severe concomitant injury, who have a service length of 10 years or more, in order to optimize respiratory support.Subjects and methods. Pulmonary gas exchange and mechanical properties were studied over time in the presence of respiratory failure (acute lung injury/acute respiratory distress syndrome in 34 miners and 36 victims (a control group with severe concomitant injury who had no underground service length. Both groups were matched in age, severity and nature of traumatic lesions and surgical interventions. Pulmonary gas exchange and mechanical properties were evaluated by the following indices: oxygen fraction in an inspired gas mixture; hemoglobin saturation and partial arterial blood oxygen and carbon dioxide tension with the alveolar-arterial gradient being calculated by the oxygen level; oxygenation index; intrapulmonary shunting; statistical compliance and airways resistance.Results. The studies demonstrated that the miners, as compared with the controls, had more pronounced gas exchange changes within 5—7 post-traumatic days; later on (days 7—9 the above differences were undetectable. Impaired pulmonary mechanical properties in the miners persisted throughout the study while in the control group, their recovery started just on day 3. The course of respiratory failure in the miners was attributable to the baseline external respiratory function. Their respiratory support was performed during 14.5±1.4 days versus 9.5±1.9 days in the controls. In the miners, the mean bed-days at an intensive care unit were 18.5±2.2 whereas in the controls those were 12.3±2.1.Conclusion. More significant impairments of pulmonary gas exchange and mechanical properties are seen in the miners due to the background changes in external respiratory function in the development of respiratory

Hybrid Approximate Dynamic Programming Approach for Dynamic Optimal Energy Flow in the Integrated Gas and Power Systems

DEFF Research Database (Denmark)

Shuai, Hang; Ai, Xiaomeng; Wen, Jinyu

2017-01-01

This paper proposes a hybrid approximate dynamic programming (ADP) approach for the multiple time-period optimal power flow in integrated gas and power systems. ADP successively solves Bellman's equation to make decisions according to the current state of the system. So, the updated near future...

Comparison of molecular dynamics and kinetic modeling of gas-surface interactions

NARCIS (Netherlands)

Frezzotti, A.; Gaastra - Nedea, S.V.; Markvoort, A.J.; Spijker, P.; Gibelli, L.

2008-01-01

The interaction of a dilute monatomic gas with a solid surface is studied byMolecular Dynamics (MD) simulations and by numerical solutions of a recently proposed kinetic model. Following previous investigations, the heat transport between parallel walls and Couette flow have been adopted as test

Price dynamics in the market for Liquid Petroleum Gas transport

International Nuclear Information System (INIS)

Adland, Roar; Jia Haiying; Lu Jing

2008-01-01

The purpose of this paper is to investigate the dynamics of the spot freight rate in the Liquid Petroleum Gas (LPG) shipping market. The spot freight rate process is nonparametrically specified so that the model allows for maximal flexibility in fitting the data. The model is estimated using data for the Very Large Gas Carrier (VLGC) sector and the estimation results are compared to those of crude oil tankers available in the literature. The empirical results suggest that the LPG spot freight rate can be appropriately described by a simple linear stochastic model and does not exhibit the non-linearity found in other bulk shipping sectors

Quench dynamics of the interacting Bose gas in one dimension.

Science.gov (United States)

Iyer, Deepak; Andrei, Natan

2012-09-14

We obtain an exact expression for the time evolution of the interacting Bose gas following a quench from a generic initial state using the Yudson representation for integrable systems. We study the time evolution of the density and noise correlation for a small number of bosons and their asymptotic behavior for any number. We show that for any value of the coupling, as long as it is repulsive, the system asymptotes towards a strongly repulsive gas, while for any value of an attractive coupling the long time behavior is dominated by the maximal bound state. This occurs independently of the initial state and can be viewed as an emerging "dynamic universality."

Phylogeny and population dynamics of respiratory syncytial virus (Rsv) A and B.

Science.gov (United States)

Martinelli, Marianna; Frati, Elena Rosanna; Zappa, Alessandra; Ebranati, Erika; Bianchi, Silvia; Pariani, Elena; Amendola, Antonella; Zehender, Gianguglielmo; Tanzi, Elisabetta

2014-08-30

Respiratory syncytial virus (RSV) is a major cause of lower respiratory tract infections in infants and young children. RSV is characterised by high variability, especially in the G glycoprotein, which may play a significant role in RSV pathogenicity by allowing immune evasion. To reconstruct the origin and phylodynamic history of RSV, we evaluated the genetic diversity and evolutionary dynamics of RSV A and RSV B isolated from children under 3 years old infected in Italy from 2006 to 2012. Phylogenetic analysis revealed that most of the RSV A sequences clustered with the NA1 genotype, and RSV B sequences were included in the Buenos Aires genotype. The mean evolutionary rates for RSV A and RSV B were estimated to be 2.1 × 10(-3) substitutions (subs)/site/year and 3.03 × 10(-3) subs/site/year, respectively. The time of most recent common ancestor for the tree root went back to the 1940s (95% highest posterior density-HPD: 1927-1951) for RSV A and the 1950s (95%HPD: 1951-1960) for RSV B. The RSV A Bayesian skyline plot (BSP) showed a decrease in transmission events ending in about 2005, when a sharp growth restored the original viral population size. RSV B BSP showed a similar trend. Site-specific selection analysis identified 10 codons under positive selection in RSV A sequences and only one site in RSV B sequences. Although RSV remains difficult to control due to its antigenic diversity, it is important to monitor changes in its coding sequences, to permit the identification of future epidemic strains and to implement vaccine and therapy strategies. Copyright © 2014 Elsevier B.V. All rights reserved.

Dynamic respiratory gated 18FDG-PET of lung tumors - a feasibility study

International Nuclear Information System (INIS)

Skjei Knudtsen, Ingerid; Skretting, Arne; Roedal, Jan; Brustugun, Odd Terje; Helland, Aaslaug; Malinen, Eirik

2011-01-01

Background. 18 FDG-PET/CT imaging is well established for diagnosis and staging of lung tumors. However, more detailed information regarding the distribution of FDG within the tumor, also as a function of time after injection may be relevant. In this study we explore the feasibility of a combined dynamic and respiratory gated (DR) PET protocol. Material and methods. A DR FDG-PET protocol for a Siemens Biograph 16 PET/CT scanner was set up, allowing data acquisition from the time of FDG injection. Breath-hold (BH) respiratory gating was performed at four intervals over a total acquisition time of 50 minutes. Thus, the PET protocol provides both motion-free images and a spatiotemporal characterization of the glucose distribution in lung tumors. Software tools were developed in-house for tentative tumor segmentation and for extracting standard uptake values (SUVs) voxel by voxel, tumor volumes and SUV gradients in all directions. Results. Four pilot patients have been investigated with the DR PET protocol. The procedure was well tolerated by the patients. The BH images appeared sharper, and SUV max /SUV mean was higher, compared to free breathing (FB) images. Also, SUV gradients in the periphery of the tumor in the BH images were in general greater than or equal to the gradients in the FB PET images. Conclusion. The DR FDG-PET protocol is feasible and the BH images have a superior quality compared to the FB images. The protocol may also provide information of relevance for radiotherapy planning and follow-up. A patient trial is needed for assessing the clinical value of the imaging protocol

Diatomic infrared gas-dynamic laser

International Nuclear Information System (INIS)

Mckenzie, R.L.

1971-01-01

A laser is provided which utilizes the infrared vibration rotation transitions of a diatomic gas such as carbon monoxide. The laser action is produced by an active diatomic gas such as carbon monoxide mixed with a vibrationally resonant pumping gas such as nitrogen. In addition, a noble gas such as argon may be employed as a third gas in the mixture. The gas mixture contains from 1 to 80 vol percent of the active gas based on the pumping gas, and the third gas, if used, can constitute up to 90 percent of the total gas volume. A number of significantly different wavelengths can be produced by the laser. A single laser may contain several optical resonators at different locations, so that the desired wave length can be selected at will

Afferent Neural Feedback Overrides the Modulating Effects of Arousal, Hypercapnia and Hypoxemia on Neonatal Cardio-respiratory Control.

Science.gov (United States)

Lumb, Kathleen J; Schneider, Jennifer M; Ibrahim, Thowfique; Rigaux, Anita; Hasan, Shabih U

2018-04-20

Evidence at whole animal, organ-system, and cellular and molecular levels suggests that afferent volume feedback is critical for establishment of adequate ventilation at birth. Due to the irreversible nature of vagal ablation studies to date, it was difficult to quantify the roles of afferent volume input, arousal and changes in blood gas tensions on neonatal respiratory control. During reversible perineural vagal block, profound apneas, and hypoxemia and hypercarbia were observed necessitating termination of perineural blockade. Respiratory depression and apneas were independent of the sleep states. We demonstrate that profound apneas and life-threatening respiratory failure in vagally denervated animals do not result from lack of arousal or hypoxemia. Change in sleep state and concomitant respiratory depression result from lack of afferent volume feedback, which appears to be critical for the maintenance of normal breathing patterns and adequate gas exchange during the early postnatal period. Afferent volume feedback plays a vital role in neonatal respiratory control. Mechanisms for the profound respiratory depression and life-threatening apneas observed in vagally denervated neonatal animals remain unclear. We investigated the roles of sleep states, hypoxic-hypercapnia and afferent volume feedback on respiratory depression using reversible perineural vagal block during early postnatal period. Seven lambs were instrumented during the first 48h of life to record/analyze sleep states, diaphragmatic electromyograph, arterial blood gas tensions, systemic arterial blood pressure and rectal temperature. Perineural cuffs were placed around the vagi to attain reversible blockade. Post-operatively, during the awake state, both vagi were blocked using 2% xylocaine for up to 30 minutes. Compared with baseline values, pHa, PaO 2 and SaO 2 decreased and PaCO 2 increased during perineural blockade (P Respiratory depression and apneas were independent of sleep states. This

Different Techniques of Respiratory Support Do Not Significantly Affect Gas Exchange during Cardiopulmonary Resuscitation in a Newborn Piglet Model.

Science.gov (United States)

Mendler, Marc R; Maurer, Miriam; Hassan, Mohammad A; Huang, Li; Waitz, Markus; Mayer, Benjamin; Hummler, Helmut D

2015-01-01

There are no evidence-based recommendations on the use of different techniques of respiratory support and chest compressions (CC) during neonatal cardiopulmonary resuscitation (CPR). We studied the short-term effects of different ventilatory support strategies along with CC representing clinical practice on gas exchange [arterial oxygen saturation (SaO2), arterial partial pressure of oxygen (PaO2) and arterial partial pressure of carbon dioxide (PaCO2)], hemodynamics and cerebral oxygenation. We hypothesized that in newborn piglets with cardiac arrest, use of a T-piece resuscitator (TPR) providing positive end-expiratory pressure (PEEP) improves gas exchange as measured by SaO2 during CPR as compared to using a self-inflating bag (SIB) without PEEP. Furthermore, we explored the effects of a mechanical ventilator without synchrony to CC. Thirty newborn piglets with asystole were randomized into three groups and resuscitated for 20 min [fraction of inspired oxygen (FiO2) = 0.21 for 10 min and 1.0 thereafter]. Group 1 received ventilation using a TPR [peak inspiratory pressure (PIP)/PEEP of 20/5 cm H2O, rate 30/min] with inflations interposed between CC (3:1 ratio). Group 2 received ventilation using a SIB (PIP of 20 cm H2O without PEEP, rate 30/min) with inflations interposed between CC (3:1 ratio). Group 3 received ventilation using a mechanical ventilator (PIP/PEEP of 20/5 cm H2O, rate 30/min). CC were applied with a rate of 120/min without synchrony to inflations. We found no significant differences in SaO2 between the three groups. However, there was a trend toward a higher SaO2 [TPR: 28.0% (22.3-40.0); SIB: 23.7% (13.4-52.3); ventilator: 44.1% (39.2-54.3); median (interquartile range)] and a lower PaCO2 [TPR: 95.6 mm Hg (82.1-113.6); SIB: 100.8 mm Hg (83.0-108.0); ventilator: 74.1 mm Hg (68.5-83.1); median (interquartile range)] in the mechanical ventilator group. We found no significant effect on gas exchange using different respiratory support strategies

Exploratory investigation of the HIPPO gas-jet target fluid dynamic properties

Energy Technology Data Exchange (ETDEWEB)

Meisel, Zach, E-mail: zmeisel@nd.edu [Department of Physics, Joint Institute for Nuclear Astrophysics, University of Notre Dame, Notre Dame, IN 46556 (United States); Shi, Ke; Jemcov, Aleksandar [Hessert Laboratory for Aerospace Research, Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN 46556 (United States); Couder, Manoel [Department of Physics, Joint Institute for Nuclear Astrophysics, University of Notre Dame, Notre Dame, IN 46556 (United States)

2016-08-21

In order to optimize the performance of gas-jet targets for future nuclear reaction measurements, a detailed understanding of the dependence of the gas-jet properties on experiment design parameters is required. Common methods of gas-jet characterization rely on measuring the effective thickness using nuclear elastic scattering and energy loss techniques; however, these tests are time intensive and limit the range of design modifications which can be explored to improve the properties of the jet as a nuclear reaction target. Thus, a more rapid jet-characterization method is desired. We performed the first steps towards characterizing the gas-jet density distribution of the HIPPO gas-jet target at the University of Notre Dame's Nuclear Science Laboratory by reproducing results from {sup 20}Ne(α,α){sup 20}Ne elastic scattering measurements with computational fluid dynamics (CFD) simulations performed with the state-of-the-art CFD software ANSYS Fluent. We find a strong sensitivity to experimental design parameters of the gas-jet target, such as the jet nozzle geometry and ambient pressure of the target chamber. We argue that improved predictive power will require moving to three-dimensional simulations and additional benchmarking with experimental data.

FIRST OPERATING RESULTS OF A DYNAMIC GAS BEARING TURBINE IN AN INDUSTRIAL HYDROGEN LIQUEFIER

International Nuclear Information System (INIS)

Bischoff, S.; Decker, L.

2010-01-01

Hydrogen has been brought into focus of industry and public since fossil fuels are depleting and costs are increasing dramatically. Beside these issues new high-tech processes in the industry are in need for hydrogen at ultra pure quality. To achieve these requirements and for efficient transportation, hydrogen is liquefied in industrial plants. Linde Gas has commissioned a new 5.5 TPD Hydrogen liquefier in Leuna, Germany, which has been engineered and supplied by Linde Kryotechnik. One of the four expansion turbines installed in the liquefaction process is equipped with dynamic gas bearings. Several design features and operational characteristics of this application will be discussed. The presentation will include results of efficiency and operational reliability that have been determined from performance tests. The advantages of the Linde dynamic gas bearing turbine for future use in hydrogen liquefaction plants will be shown.

The use of Rheum palmatum L. In the treatment of acute respiratory ...

African Journals Online (AJOL)

The use of Rheum palmatum L. In the treatment of acute respiratory distress syndrome: a meta-analysis of randomized, controlled trials. ... If the lung ventilation dysfunction is caused by inflammatory exudate or secretions obstruction of the small airway ventilation, blood gas partial pressure is increased and intestinal gas ...

Respiratory system. Part 2: Gaseous exchange.

Science.gov (United States)

McLafferty, Ella; Johnstone, Carolyn; Hendry, Charles; Farley, Alistair

This article, which isthe last in the life sciences series and the second of two articles on the respiratory system, describes gaseous exchange in the lungs, transport of oxygen and carbon dioxide, and internal and external respiration. The article concludes with a brief consideration of two conditions that affect gas exchange and transport: carbon monoxide poisoning and chronic obstructive pulmonary disease.

Lattice gas simulations of dynamical geometry in one dimension.

Science.gov (United States)

Love, Peter J; Boghosian, Bruce M; Meyer, David A

2004-08-15

We present numerical results obtained using a lattice gas model with dynamical geometry. The (irreversible) macroscopic behaviour of the geometry (size) of the lattice is discussed in terms of a simple scaling theory and obtained numerically. The emergence of irreversible behaviour from the reversible microscopic lattice gas rules is discussed in terms of the constraint that the macroscopic evolution be reproducible. The average size of the lattice exhibits power-law growth with exponent at late times. The deviation of the macroscopic behaviour from reproducibility for particular initial conditions ('rogue states') is investigated as a function of system size. The number of such 'rogue states' is observed to decrease with increasing system size. Two mean-field analyses of the macroscopic behaviour are also presented. Copyright 2004 The Royal Society

The dynamic characteristics of HTGR (High Temperature Gas Cooled Reactor) system, (2)

International Nuclear Information System (INIS)

Kudo, Kazuhiko; Ohta, Masao; Kawasaki, Hidenori

1979-01-01

The dynamic characteristics of a HTGR plant, which has two cooling loops, was investigated. The analytical model consists of the core with fuel sleeves, coolant channels and blocks, the upper and lower reflectors, the high and low temperature plenums, two double wall pipings, two intermediate heat exchangers and the secondary system. The key plant parameters for calculation were as follows: the core outlet gas temperature 1000 deg C, the reactor thermal output 50 MW, the flow rate of primary coolant gas 7.96 kg/sec-loop and the pressure of primary coolant gas 40 kg/cm 2 at the rated operating condition. The calculating parameters were fixed as follows: the time interval for core characteristic analysis 0.1 sec, the time interval for thermal characteristic analysis 5.0 sec, the number of division of fuel channels 130, and the number of division of an intermediate heat exchanger 200. The assumptions for making the model were evaluated especially for the power distribution in the core and the heat transmission coefficients in the core, the double wall piping and the intermediate heat exchangers. Concerning the analytical results, the self-control to the outer disturbance of reactivity and the plant dynamic behavior due to the change of flow rate of primary and secondary coolants, and the change of gas temperature of secondary coolant at the inlet of intermediate heat exchangers, are presented. (Nakai, Y.)

Modeling the Gas Dynamics Environment in a Subscale Solid Rocket Test Motor

Science.gov (United States)

Eaton, Andrew M.; Ewing, Mark E.; Bailey, Kirk M.; McCool, Alex (Technical Monitor)

2001-01-01

Subscale test motors are often used for the evaluation of solid rocket motor component materials such as internal insulation. These motors are useful for characterizing insulation performance behavior, screening insulation material candidates and obtaining material thermal and ablative property design data. One of the primary challenges associated with using subscale motors however, is the uncertainty involved when extrapolating the results to full-scale motor conditions. These uncertainties are related to differences in such phenomena as turbulent flow behavior and boundary layer development, propellant particle interactions with the wall, insulation off-gas mixing and thermochemical reactions with the bulk flow, radiation levels, material response to the local environment, and other anomalous flow conditions. In addition to the need for better understanding of physical mechanisms, there is also a need to better understand how to best simulate these phenomena using numerical modeling approaches such as computational fluid dynamics (CFD). To better understand and model interactions between major phenomena in a subscale test motor, a numerical study of the internal flow environment of a representative motor was performed. Simulation of the environment included not only gas dynamics, but two-phase flow modeling of entrained alumina particles like those found in an aluminized propellant, and offgassing from wall surfaces similar to an ablating insulation material. This work represents a starting point for establishing the internal environment of a subscale test motor using comprehensive modeling techniques, and lays the groundwork for improving the understanding of the applicability of subscale test data to full-scale motors. It was found that grid resolution, and inclusion of phenomena in addition to gas dynamics, such as two-phase and multi-component gas composition are all important factors that can effect the overall flow field predictions.

Modeling beam-front dynamics at low gas pressures

International Nuclear Information System (INIS)

Briggs, R.J.; Yu, S.

1982-01-01

The dynamics of space charge neutralization at the front of an intense self-focused electron beam pulse exhibits important differences in different gas pressure regimes. At very low pressures, the beam front is in the so-called ion-focused regime (IFR) where all secondary electrons are expelled from the beam region by the radial electric field without causing significant additional ionization. We estimate the upper pressure boundary of this regime by considering the distance scale length for cascade (avalanche) ionization. Data from the FX-25 diode experiments indicate a critical transition pressure (P/sub c/) that agrees with this estimate and with its scaling among various gas types. Normal mobility-limited treatments (local conductivity models) of the secondary electrons at the beam front are not justified until the gas pressure is 10 to 50 times higher than P/sub c/, due to runaway of these secondary electrons in the strong space-charge electric field at the lower pressures. The main conclusion of this study is that a non-local phase space (Boltzmann) treatment of the secondary electrons is required to accurately describe these different beam front regimes and the transitions between them; such a code model is currently under development

Dynamics of polynomial Chaplygin gas warm inflation

Energy Technology Data Exchange (ETDEWEB)

Jawad, Abdul [COMSATS Institute of Information Technology, Department of Mathematics, Lahore (Pakistan); Chaudhary, Shahid [Sharif College of Engineering and Technology, Department of Mathematics, Lahore (Pakistan); Videla, Nelson [Pontificia Universidad Catolica de Valparaiso, Instituto de Fisica, Valparaiso (Chile)

2017-11-15

In the present work, we study the consequences of a recently proposed polynomial inflationary potential in the context of the generalized, modified, and generalized cosmic Chaplygin gas models. In addition, we consider dissipative effects by coupling the inflation field to radiation, i.e., the inflationary dynamics is studied in the warm inflation scenario. We take into account a general parametrization of the dissipative coefficient Γ for describing the decay of the inflaton field into radiation. By studying the background and perturbative dynamics in the weak and strong dissipative regimes of warm inflation separately for the positive and negative quadratic and quartic potentials, we obtain expressions for the most relevant inflationary observables as the scalar power spectrum, the scalar spectral, and the tensor-to-scalar ratio. We construct the trajectories in the n{sub s}-r plane for several expressions of the dissipative coefficient and compare with the two-dimensional marginalized contours for (n{sub s}, r) from the latest Planck data. We find that our results are in agreement with WMAP9 and Planck 2015 data. (orig.)

Gas gun dynamics

International Nuclear Information System (INIS)

Denny, Mark

2013-01-01

The mechanics and thermodynamics of one- and two-stage gas guns are developed. Very high projectile muzzle speed can be obtained by the two-stage version. The physics of simple gas guns, such as air rifles, is accessible to undergraduates and the same level of presentation is used here to understand more complex designs. Numerical solutions to the equations of motion are shown, along with insightful analytic approximations. (paper)

Effects of Gas Rarefaction on Dynamic Characteristics of Micro Spiral-Grooved Thrust Bearing.

Science.gov (United States)

Liu, Ren; Wang, Xiao-Li; Zhang, Xiao-Qing

2012-04-01

The effects of gas-rarefaction on dynamic characteristics of micro spiral-grooved-thrust-bearing are studied. The Reynolds equation is modified by the first order slip model, and the corresponding perturbation equations are then obtained on the basis of the linear small perturbation method. In the converted spiral-curve-coordinates system, the finite-volume-method (FVM) is employed to discrete the surface domain of micro bearing. The results show, compared with the continuum-flow model, that under the slip-flow regime, the decrease in the pressure and stiffness become obvious with the increasing of the compressibility number. Moreover, with the decrease of the relative gas-film-thickness, the deviations of dynamic coefficients between slip-flow-model and continuum-flow-model are increasing.

Dynamic behaviour of high-pressure natural-gas flow in pipelines

International Nuclear Information System (INIS)

Gato, L.M.C.; Henriques, J.C.C.

2005-01-01

The aim of the present study is the numerical modelling of the dynamic behaviour of high-pressure natural-gas flow in pipelines. The numerical simulation was performed by solving the conservation equations, for one-dimensional compressible flow, using the Runge-Kutta discontinuous Galerkin method, with third-order approximation in space and time. The boundary conditions were imposed using a new weak formulation based on the characteristic variables. The occurrence of pressure oscillations in natural-gas pipelines was studied as a result of the compression wave originated by the rapid closure of downstream shut-off valves. The effect of the partial reflection of pressure waves was also analyzed in the transition between pipes of different cross-sectional areas

Dynamic behaviour of high-pressure natural-gas flow in pipelines

Energy Technology Data Exchange (ETDEWEB)

Gato, L.M.C. [Department of Mechanical Engineering, Instituto Superior Tecnico, Technical University of Lisbon, Av. Rovisco Pais, 1049-001 Lisbon (Portugal)]. E-mail: lgato@mail.ist.utl.pt; Henriques, J.C.C. [Department of Mechanical Engineering, Instituto Superior Tecnico, Technical University of Lisbon, Av. Rovisco Pais, 1049-001 Lisbon (Portugal)]. E-mail: jcch@mail.ist.utl.pt

2005-10-01

The aim of the present study is the numerical modelling of the dynamic behaviour of high-pressure natural-gas flow in pipelines. The numerical simulation was performed by solving the conservation equations, for one-dimensional compressible flow, using the Runge-Kutta discontinuous Galerkin method, with third-order approximation in space and time. The boundary conditions were imposed using a new weak formulation based on the characteristic variables. The occurrence of pressure oscillations in natural-gas pipelines was studied as a result of the compression wave originated by the rapid closure of downstream shut-off valves. The effect of the partial reflection of pressure waves was also analyzed in the transition between pipes of different cross-sectional areas.

Collective dynamics in noble-gas and other very simple classical fluids

Directory of Open Access Journals (Sweden)

U.Bafile

2008-03-01

Full Text Available Rare gases and their liquids are the simplest systems to study for accurate investigations of the collective dynamics of fluid matter. Much work has been done using different spectroscopic techniques, molecular-dynamics simulations, and theoretical developments, in order to gain insight into the microscopic processes involved, in particular, in the propagation of acoustic excitations in gases and liquids. Here we briefly review the interpretation schemes currently applied to the characterization of such excitations, and recall a few results obtained from the analysis of rare-gas fluids and other very simple systems.

Robust Design of SAW Gas Sensors by Taguchi Dynamic Method

Directory of Open Access Journals (Sweden)

Hsun-Heng Tsai

2009-02-01

Full Text Available This paper adopts Taguchi’s signal-to-noise ratio analysis to optimize the dynamic characteristics of a SAW gas sensor system whose output response is linearly related to the input signal. The goal of the present dynamic characteristics study is to increase the sensitivity of the measurement system while simultaneously reducing its variability. A time- and cost-efficient finite element analysis method is utilized to investigate the effects of the deposited mass upon the resonant frequency output of the SAW biosensor. The results show that the proposed methodology not only reduces the design cost but also promotes the performance of the sensors.

Response Functions for the Two-Dimensional Ultracold Fermi Gas: Dynamical BCS Theory and Beyond

Science.gov (United States)

Vitali, Ettore; Shi, Hao; Qin, Mingpu; Zhang, Shiwei

2017-12-01

Response functions are central objects in physics. They provide crucial information about the behavior of physical systems, and they can be directly compared with scattering experiments involving particles such as neutrons or photons. Calculations of such functions starting from the many-body Hamiltonian of a physical system are challenging and extremely valuable. In this paper, we focus on the two-dimensional (2D) ultracold Fermi atomic gas which has been realized experimentally. We present an application of the dynamical BCS theory to obtain response functions for different regimes of interaction strengths in the 2D gas with zero-range attractive interaction. We also discuss auxiliary-field quantum Monte Carlo (AFQMC) methods for the calculation of imaginary time correlations in these dilute Fermi gas systems. Illustrative results are given and comparisons are made between AFQMC and dynamical BCS theory results to assess the accuracy of the latter.

Evolution of collision numbers for a chaotic gas dynamics.

Science.gov (United States)

Vidgop, Alexander Jonathan; Fouxon, Itzhak

2011-11-01

We put forward a conjecture of recurrence for a gas of hard spheres that collide elastically in a finite volume. The dynamics consists of a sequence of instantaneous binary collisions. We study how the numbers of collisions of different pairs of particles grow as functions of time. We observe that these numbers can be represented as a time integral of a function on the phase space. Assuming the results of the ergodic theory apply, we describe the evolution of the numbers by an effective Langevin dynamics. We use the facts that hold for these dynamics with probability one, in order to establish properties of a single trajectory of the system. We find that for any triplet of particles there will be an infinite sequence of moments of time, when the numbers of collisions of all three different pairs of the triplet will be equal. Moreover, any value of difference of collision numbers of pairs in the triplet will repeat indefinitely. On the other hand, for larger numbers of pairs there is but a finite number of repetitions. Thus the ergodic theory produces a limitation on the dynamics.

Parametric study on ship’s exhaust-gas behavior using computational fluid dynamics

Directory of Open Access Journals (Sweden)

Sunho Park

2017-01-01

Full Text Available The influence of design parameters related to a ship’s exhaust-gas behavior was investigated using computational fluid dynamics (CFD for an 8,000 TEU container carrier. To verify the numerical methods, the results were studied by comparing with experimental results. Several test conditions, i.e. various load conditions of ship, wind angle, deckhouse breadth, radar mast height, and exhaust-pipe height and shape were considered for a ship’s exhaust gas flow around the 8,000 TEU container carrier. The influence of the design parameters on contamination by the exhaust gas was quantified, after which the principal parameters to avoid contamination were selected. Finally, the design guideline of yP/H = 2 was suggested to avoid the contamination from the ship’s exhaust gas using the CFD results, model tests, and sea trials.

Respiratory challenge MRI: Practical aspects

Directory of Open Access Journals (Sweden)

Fiona C. Moreton

2016-01-01

Full Text Available Respiratory challenge MRI is the modification of arterial oxygen (PaO2 and/or carbon dioxide (PaCO2 concentration to induce a change in cerebral function or metabolism which is then measured by MRI. Alterations in arterial gas concentrations can lead to profound changes in cerebral haemodynamics which can be studied using a variety of MRI sequences. Whilst such experiments may provide a wealth of information, conducting them can be complex and challenging. In this paper we review the rationale for respiratory challenge MRI including the effects of oxygen and carbon dioxide on the cerebral circulation. We also discuss the planning, equipment, monitoring and techniques that have been used to undertake these experiments. We finally propose some recommendations in this evolving area for conducting these experiments to enhance data quality and comparison between techniques.

Modelling dynamic liquid-gas systems: Extensions to the volume-of-fluid solver

CSIR Research Space (South Africa)

Heyns, Johan A

2013-06-01

Full Text Available This study presents the extension of the volume-of-fluid solver, interFoam, for improved accuracy and efficiency when modelling dynamic liquid-gas systems. Examples of these include the transportation of liquids, such as in the case of fuel carried...

Transmission of severe acute respiratory syndrome in dynamical small-world networks

Science.gov (United States)

Masuda, Naoki; Konno, Norio; Aihara, Kazuyuki

2004-03-01

The outbreak of severe acute respiratory syndrome (SARS) is still threatening the world because of a possible resurgence. In the current situation that effective medical treatments such as antiviral drugs are not discovered yet, dynamical features of the epidemics should be clarified for establishing strategies for tracing, quarantine, isolation, and regulating social behavior of the public at appropriate costs. Here we propose a network model for SARS epidemics and discuss why superspreaders emerged and why SARS spread especially in hospitals, which were key factors of the recent outbreak. We suggest that superspreaders are biologically contagious patients, and they may amplify the spreads by going to potentially contagious places such as hospitals. To avoid mass transmission in hospitals, it may be a good measure to treat suspected cases without hospitalizing them. Finally, we indicate that SARS probably propagates in small-world networks associated with human contacts and that the biological nature of individuals and social group properties are factors more important than the heterogeneous rates of social contacts among individuals. This is in marked contrast with epidemics of sexually transmitted diseases or computer viruses to which scale-free network models often apply.

Dynamic Stability Study of Static Gas Bearing for Small Cryogenic Turbo-Expander

International Nuclear Information System (INIS)

Wang Xuemin; Zhuang Ming; Zhang Qiyong; Li Shanshan; Fu Bao

2011-01-01

An experimental method is presented to analyze the dynamic stability of the gas bearing for small cryogenic turbo-expanders. The rotation imbalance response and the shape of the rotor orbit were obtained for different speeds up to 110,000 rpm, and the critical speed of the rotor-bearing system was determined by a Bode diagram. An FFT signal analytical method was applied to identify the resonance frequency, and the waterfall plot was presented. During the whole process of speeding up to the designed speed of 110,000 rpm, the rotor-bearing works stably with no whirl instability, which is validated in a waterfall plot. Also, the tested rotor-bearing model was analyzed theoretically. It was proved that the experimental results were highly consistent with those of theoretical calculations. Thus the experimental method proposed here to analyze the dynamic stability of the gas bearing is feasible. (fusion engineering)

42 CFR 84.117 - Gas mask containers; minimum requirements.

Science.gov (United States)

2010-10-01

... 42 Public Health 1 2010-10-01 2010-10-01 false Gas mask containers; minimum requirements. 84.117... SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY PROTECTIVE DEVICES Gas Masks § 84.117 Gas mask containers; minimum requirements. (a) Gas masks shall be equipped with a substantial...

Quantum quench dynamics of the attractive one-dimensional Bose gas via the coordinate Bethe ansatz

Directory of Open Access Journals (Sweden)

Jan C. Zill, Tod M. Wright, Karen V. Kheruntsyan, Thomas Gasenzer, Matthew J. Davis

2018-02-01

Full Text Available We use the coordinate Bethe ansatz to study the Lieb-Liniger model of a one-dimensional gas of bosons on a finite-sized ring interacting via an attractive delta-function potential. We calculate zero-temperature correlation functions for seven particles in the vicinity of the crossover to a localized solitonic state and study the dynamics of a system of four particles quenched to attractive interactions from the ideal-gas ground state. We determine the time evolution of correlation functions, as well as their temporal averages, and discuss the role of bound states in shaping the postquench correlations and relaxation dynamics.

The development and application of dynamic operational risk assessment in oil/gas and chemical process industry

International Nuclear Information System (INIS)

Yang Xiaole; Mannan, M. Sam

2010-01-01

A methodology of dynamic operational risk assessment (DORA) is proposed for operational risk analysis in oil/gas and chemical industries. The methodology is introduced comprehensively starting from the conceptual framework design to mathematical modeling and to decision making based on cost-benefit analysis. The probabilistic modeling part of DORA integrates stochastic modeling and process dynamics modeling to evaluate operational risk. The stochastic system-state trajectory is modeled according to the abnormal behavior or failure of each component. For each of the possible system-state trajectories, a process dynamics evaluation is carried out to check whether process variables, e.g., level, flow rate, temperature, pressure, or chemical concentration, remain in their desirable regions. Component testing/inspection intervals and repair times are critical parameters to define the system-state configuration, and play an important role for evaluating the probability of operational failure. This methodology not only provides a framework to evaluate the dynamic operational risk in oil/gas and chemical industries, but also guides the process design and further optimization. To illustrate the probabilistic study, we present a case-study of a level control in an oil/gas separator at an offshore plant.

Dynamics of exciplex formation in rare gas media

International Nuclear Information System (INIS)

Rojas-Lorenzo, German; Rubayo-Soneira, Jesus; Alberti, Sebastian Fernandez

2009-01-01

A hopping-surface algorithm has been used to simulate the dynamics induced in rare gas matrices due to the photoexcitation ( 1 S 0 → 3 P 1 ) of atomic mercury embedded in them. Especially, the study of the dynamics of an exciplex formation in a model system consisting of solid xenon doped with atomic mercury. The process starts upon the photoexcitation of the Hg atom to its 3 P 1 electronic excited state. Diatomics-in-Molecule approach has been used for constructing the adiabatic potential surfaces. In all trajectories we show that a triatomic Xe-Hg * -Xe complex is formed, but in two conformations: bent and linear. The mechanisms leading to the formation of one or the other are identified. Mainly, are noted the thermal fluctuations of the Hg impurity and the shape of the potential surfaces. Furthermore, we show that non-radiative intrastate relaxation occurs via a conical intersection between the excited state surfaces. The simulated spectra are in very good agreement with the experimental data.

Gas flow characteristics of a time modulated APPJ: the effect of gas heating on flow dynamics

International Nuclear Information System (INIS)

Zhang, S; Sobota, A; Van Veldhuizen, E M; Bruggeman, P J

2015-01-01

This work investigates the flow dynamics of a radio-frequency (RF) non-equilibrium argon atmospheric pressure plasma jet. The RF power is at a frequency of 50 Hz or 20 kHz. Combined flow pattern visualizations (obtained by shadowgraphy) and gas temperature distributions (obtained by Rayleigh scattering) are used to study the formation of transient vortex structures in initial flow field shortly after the plasma is switched on and off in the case of 50 Hz modulation. The transient vortex structures correlate well with observed temperature differences. Experimental results of the fast modulated (20 kHz) plasma jet that does not induce changes of the gas temperature are also presented. The latter result suggests that momentum transfer by ions does not have dominant effect on the flow pattern close to the tube. It is argued that the increased gas temperature and corresponding gas velocity increase at the tube exit due to the plasma heating increases the admixing of surrounding air and reduces the effective potential core length. With increasing plasma power a reduction of the effective potential core length is observed with a minimum length for 5.6 W after which the length extends again. Possible mechanisms related to viscosity effects and ionic momentum transfer are discussed. (paper)

Gas dynamic virtual nozzle for generation of microscopic droplet streams

Energy Technology Data Exchange (ETDEWEB)

DePonte, D P; Weierstall, U; Schmidt, K; Warner, J; Starodub, D; Spence, J C H; Doak, R B [Department of Physics, Arizona State University, Tempe, AZ 85287-1504 (United States)], E-mail: dandeponte@gmail.com

2008-10-07

As shown by Ganan-Calvo (1998 Phys. Rev. Lett. 80 285-8), a free liquid jet can be compressed in diameter through gas dynamic forces exerted by a coaxially co-flowing gas, obviating the need for a solid nozzle to form a microscopic liquid jet and thereby alleviating the clogging problems that plague conventional droplet sources of small diameter. We describe in this paper a novel form of droplet beam source based on this principle. The source is miniature, robust, dependable, easily fabricated, essentially immune to clogging and eminently suitable for delivery of microscopic liquid droplets, including hydrated biological samples, into vacuum for analysis using vacuum instrumentation. Monodisperse, single-file droplet streams are generated by triggering the device with a piezoelectric actuator.

A time-dependent dusty gas dynamic model of axisymmetric cometary jets

International Nuclear Information System (INIS)

Korosmezey, A.; Gombosi, T.I.

1990-01-01

The present time-dependent, axisymmetric dusty gas dynamical model of inner cometary atmospheres solves the coupled and time-dependent equations of continuity, momentum, and energy for a gas-dust mixture between the surface of the nucleus and 100 km, using an axisymmetric 40 x 40 grid structure. A novel numerical method employing a second-order accurate Godunov-type scheme with dimensional splitting is used to solve the time-dependent pde system. It is established that a subsolar dust spike not predicted by previous calculations is generated by narrow axisymmetric jets, together with a jet cone whose opening angle depends on the jet length. 28 refs

A dynamic model of gas flow in a non-uniform pipe

International Nuclear Information System (INIS)

Mensah, S.; Lepp, R.M.

1979-08-01

A gas-line model, based on the analysis of compressible flow with friction, has been developed to describe the dynamics of gas flow in a non-uniform line, i.e. one comprising segments of different lengths and diameters. Acoustic wave analysis was used in a novel way, by considering the line as a cascaded connection of uniform pipes separated by discontinuities. The transmission matrix representing this non-uniform line is the product of the matrices for each element in the system. To facilitate implementation of the theoretical model on a hybrid computer, modal approximatons to its transfer functions were derived. Both models were validated against experimental data. (author)

Respiratory Therapy for Acute Lung Lesion, by Using Biphasic Positive Pressure Ventilation

Directory of Open Access Journals (Sweden)

Yu. V. Marchenkov

2005-01-01

Full Text Available Objective. To comparatively study the efficiency of respiratory support in patients with acute lung lesion, by applying BIPAP, SIMV, and aIPPV.Subjects. Twenty-six patients with acute lung lesion whose pattern included acute respiratory distress syndrome (n=16, pneumonia (и=6, and pneumonitis (n=4 were examined. The severity of disease was 18 to 21 APACHE II scale score.Results. The use of BIPAP leads to a better adaptation of a patient to respiratory support, to a reduction in the number of used myorelaxants and sedatives, and to improvement of gas exchange in the lung and diminishes the negative impact of artificial ventilation on hemodynamics. As compared with other types of assisted ventilation, BIPAP accelerates transfer from total respiratory support to spontaneous breathing.

Pathophysiology of spontaneous venous gas embolism

Science.gov (United States)

Lambertsen, C. J.; Albertine, K. H.; Pisarello, J. B.; Flores, N. D.

1991-01-01

The use of controllable degrees and durations of continuous isobaric counterdiffusion venous gas embolism to investigate effects of venous gas embolism upon blood, cardiovascular, and respiratory gas exchange function, as well as pathological effects upon the lung and its microcirculation is discussed. Use of N2O/He counterdiffusion permitted performance of the pathophysiologic and pulmonary microstructural effects at one ATA without hyperbaric or hypobaric exposures.

Model-based respiratory motion compensation for emission tomography image reconstruction

International Nuclear Information System (INIS)

Reyes, M; Malandain, G; Koulibaly, P M; Gonzalez-Ballester, M A; Darcourt, J

2007-01-01

In emission tomography imaging, respiratory motion causes artifacts in lungs and cardiac reconstructed images, which lead to misinterpretations, imprecise diagnosis, impairing of fusion with other modalities, etc. Solutions like respiratory gating, correlated dynamic PET techniques, list-mode data based techniques and others have been tested, which lead to improvements over the spatial activity distribution in lungs lesions, but which have the disadvantages of requiring additional instrumentation or the need of discarding part of the projection data used for reconstruction. The objective of this study is to incorporate respiratory motion compensation directly into the image reconstruction process, without any additional acquisition protocol consideration. To this end, we propose an extension to the maximum likelihood expectation maximization (MLEM) algorithm that includes a respiratory motion model, which takes into account the displacements and volume deformations produced by the respiratory motion during the data acquisition process. We present results from synthetic simulations incorporating real respiratory motion as well as from phantom and patient data

Anisotropic relaxation dynamics in a dipolar Fermi gas driven out of equilibrium

DEFF Research Database (Denmark)

Aikawa, K.; Frisch, A.; Mark, M.

2014-01-01

We report on the observation of a large anisotropy in the rethermalization dynamics of an ultracold dipolar Fermi gas driven out of equilibrium. Our system consists of an ultracold sample of strongly magnetic $^{167}$Er fermions, spin-polarized in the lowest Zeeman sublevel. In this system, elastic...

Gas dynamics considerations in a non-invasive profile monitor for charged particle beams

CERN Document Server

Tzoganis, Vasilis; Welsch, Carsten P

2014-01-01

A non-invasive, gas jet-based, beam profile monitor has been developed in the QUASAR Group at the Cockcroft Institute, UK. This allows on-line measurement of the 2-dimensional transverse profile of particle beams with negligible disturbance to either primary beam or accelerator vacuum. The monitor is suitable for use with beams across a wide range of energies and intensities. In this setup a nozzle-skimmer system shapes a thin supersonic gas jet into a curtain. However, the small dimensions of the gas inlet nozzle and subsequent skimmers were shown to be the cause of many operational problems. In this paper, the dynamics of gas jet formation transport and shaping is discussed before an image-processing based alignment technique is introduced. Furthermore, experimental results obtained with a 5 keV electron beam are discussed and the effects of gas stagnation pressure on the acquired beam are presented.

Gas cooking, kitchen ventilation, and asthma, allergic symptoms and sensitization in young children - the PIAMA study

NARCIS (Netherlands)

Willers, SM; Brunekreef, B; Oldenwening, M; Smit, HA; Kerkhof, M; Gerritsen, J; De Jongste, JC; De Vries, H.

Background: Several studies reported inconsistent associations between using gas for cooking and respiratory symptoms or lung function in children. Kitchen ventilation characteristics may modify the relationship between gas cooking and respiratory health. The aim of this study was to investigate the

The effect of gas double-dynamic on mass distribution in solid-state fermentation.

Science.gov (United States)

Chen, Hong-Zhang; Zhao, Zhi-Min; Li, Hong-Qiang

2014-05-10

The mass distribution regularity in substrate of solid-state fermentation (SSF) has rarely been reported due to the heterogeneity of solid medium and the lack of suitable instrument and method, which limited the comprehensive analysis and enhancement of the SSF performance. In this work, the distributions of water, biomass, and fermentation product in different medium depths of SSF were determined using near-infrared spectroscopy (NIRS) and the developed models. Based on the mass distribution regularity, the effects of gas double-dynamic on heat transfer, microbial growth and metabolism, and product distribution gradient were systematically investigated. Results indicated that the maximum temperature of substrate and the maximum carbon dioxide evolution rate (CER) were 39.5°C and 2.48mg/(hg) under static aeration solid-state fermentation (SASSF) and 33.9°C and 5.38mg/(hg) under gas double-dynamic solid-state fermentation (GDSSF), respectively, with the environmental temperature for fermentation of 30±1°C. The fermentation production (cellulase activity) ratios of the upper, middle, and lower levels were 1:0.90:0.78 at seventh day under SASSF and 1:0.95:0.89 at fifth day under GDSSF. Therefore, combined with NIRS analysis, gas double-dynamic could effectively strengthen the solid-state fermentation performance due to the enhancement of heat transfer, the stimulation of microbial metabolism and the increase of the homogeneity of fermentation products. Copyright © 2014 Elsevier Inc. All rights reserved.

Mathematical modelling of a human external respiratory system

Science.gov (United States)

1977-01-01

A closed system of algebraic and common differential equations solved by computer is investigated. It includes equations which describe the activity pattern of the respiratory center, the phrenic nerve, the thrust produced by the diaphragm as a function of the lung volume and discharge frequency of the phrenic nerve, as well as certain relations of the lung stretch receptors and chemoreceptors on various lung and blood characteristics, equations for lung biomechanics, pulmonary blood flow, alveolar gas exchange and capillary blood composition equations to determine various air and blood flow and gas exchange parameters, and various gas mixing and arterial and venous blood composition equations, to determine other blood, air and gas mixing characteristics. Data are presented by means of graphs and tables, and some advantages of this model over others are demonstrated by test results.

[Aging of the respiratory system: anatomical changes and physiological consequences].

Science.gov (United States)

Ketata, W; Rekik, W K; Ayadi, H; Kammoun, S

2012-10-01

The respiratory system undergoes progressive involution with age, resulting in anatomical and functional changes that are exerted on all levels. The rib cage stiffens and respiratory muscles weaken. Distal bronchioles have reduced diameter and tend to be collapsed. Mobilized lung volumes decrease with age while residual volume increases. Gas exchanges are modified with a linear decrease of PaO(2) up to the age of 70 years and a decreased diffusing capacity of carbon monoxide. Ventilatory responses to hypercapnia, hypoxia and exercise decrease in the elderly. Knowledge of changes in the respiratory system related to advancing age is a medical issue of great importance in order to distinguish the effects of aging from those of diseases. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

Evaluation of respiratory pattern during respiratory-gated radiotherapy

International Nuclear Information System (INIS)

Dobashi, Suguru; Mori, Shinichiro

2014-01-01

The respiratory cycle is not strictly regular, and generally varies in amplitude and period from one cycle to the next. We evaluated the characteristics of respiratory patterns acquired during respiratory gating treatment in more than 300 patients. A total 331 patients treated with respiratory-gated carbon-ion beam therapy were selected from a group of patients with thoracic and abdominal conditions. Respiratory data were acquired for a total of 3,171 fractions using an external respiratory sensing monitor and evaluated for respiratory cycle, duty cycle, magnitude of baseline drift, and intrafractional/interfractional peak inhalation/exhalation positional variation. Results for the treated anatomical sites and patient positioning were compared. Mean ± SD respiratory cycle averaged over all patients was 4.1 ± 1.3 s. Mean ± SD duty cycle averaged over all patients was 36.5 ± 7.3 %. Two types of baseline drift were seen, the first decremental and the second incremental. For respiratory peak variation, the mean intrafractional variation in peak-inhalation position relative to the amplitude in the first respiratory cycle (15.5 ± 9.3 %) was significantly larger than that in exhalation (7.5 ± 4.6 %). Interfractional variations in inhalation (17.2 ± 18.5 %) were also significantly greater than those in exhalation (9.4 ± 10.0 %). Statistically significant differences were observed between patients in the supine position and those in the prone position in mean respiratory cycle, duty cycle, and intra-/interfractional variations. We quantified the characteristics of the respiratory curve based on a large number of respiratory data obtained during treatment. These results might be useful in improving the accuracy of respiratory-gated treatment.

A system dynamic model for production and consumption policy in Iran oil and gas sector

International Nuclear Information System (INIS)

Kiani, Behdad; Ali Pourfakhraei, Mohammad

2010-01-01

A system dynamic model is presented, which considers the feedback between supply and demand and oil revenue of the existing system in Iran considering different sectors of the economy. Also the export of the oil surplus and the injection of the gas surplus into the oil reservoirs are seen in the model by establishing a balance between supply and demand. In this model the counter-effects and existing system feedbacks between supply and demand and oil revenue can be seen considering different sectors of the economy. As a result, the effects of oil and gas policies in different scenarios for different sectors of Iran's economy together with the counter-effects of energy consumption and oil revenue are examined. Three scenarios, which show the worst, base and ideal cases, are considered to find future trends of major variables such as seasonal gas consumption in power plants, seasonal injected gas in oil reservoirs, economic growth in the industrial sector, oil consumption in the transportation sector, industrial gas consumption and exported gas. For example, it is shown that the exported gas will reach between 500 and 620 million cubic-meter per day in different scenarios and export revenues can reach up to $500 billion by 2025. - Research Highlights: →A system dynamic model analyzing the feedback between supply, demand and oil revenue is built. →The export of the oil surplus and the injection of the gas surplus into oil reservoirs are modeled. →Effects of oil and gas policies in different scenarios are examined for Iran's economy. →Counter-effects of energy consumption and oil revenue are examined. →Exported gas will reach between 500 and 620 million cubic-meter per day in different scenarios. →Export revenues can reach up to $500 billion by 2025.

Impact of domestic air pollution from cooking fuel on respiratory allergies in children in India

Energy Technology Data Exchange (ETDEWEB)

Kumar, R.; Nagar, J.K.; Raj, N.; Kumar, P.; Kushwah, A.S.; Meena, M.; Gaur, S.N. [University of Delhi, Delhi (India)

2008-12-15

This study undertaken in India was aimed at identifying the effects of the indoor air pollutants SO{sub 2}, NO{sub 2} and total suspended particulate matter (SPM) generated from fuel used for cooking on respiratory allergy in children in Delhi. A total of 3,456 children were examined (59.2% male and 40.8% female). Among these, 31.2% of the children's families were using biomass fuels for cooking and 68.8% were using liquefied petroleum gas. Levels of indoor SO{sub 2}, NO{sub 2} and SPM, measured using a Handy Air Sampler (Low Volume Sampler), were 4.60 {+-} 5.66 {mu}g/m{sup 3}, 30.70 {+-} 23.95 {mu}g/m{sup 3} and 705 {+-} 441.6 {mu}g/m{sup 3}, respectively. The mean level of indoor SO{sub 2} was significantly higher (p = 0.016) for families using biomass fuels (coal, wood, cow dung cakes and kerosene) for cooking as compared to families using LP gas. The mean level of indoor NO{sub 2} for families using biomass fuels for cooking was significantly higher in I.T.O. (p = 0.003) and Janakpuri (p = 0.007), while indoor SPM was significantly higher in Ashok Vihar (p = 0.039) and I.T.O. (p = 0.001), when compared to families using LP gas. Diagnoses of asthma, rhinitis and upper respiratory tract infection (URTI) were made in 7.7%, 26.1% and 22.1% of children, respectively. Respiratory allergies in children, which included asthma, rhinitis and URTI, could be associated with both types of fuels (liquefied petroleum gas (LPG) and biomass) used for cooking in the different study areas. This study suggests that biomass fuels increased the concentrations of indoor air pollutants that cause asthma, rhinitis and URTI in children. LP gas smoke was also associated with respiratory allergy.

Experimental investigation of the dynamics in a strongly interacting Fermi gas : collective modes and rotational properties

International Nuclear Information System (INIS)

Riedl, S.

2009-01-01

This thesis explores the dynamics in an ultracold strongly interacting Fermi gas. Therefore we perform measurements on collective excitation modes and rotational properties of the gas. The strongly interacting gas is realized using an optically trapped Fermi gas of 6 Li atoms, where the interactions can be tuned using a broad Feshbach resonance. Our measurements allow to test the equation of state of the gas, study the transition from hydrodynamic to collisionless behavior, reveal almost ideal hydrodynamic behavior in the nonsuperfluid phase, investigate the lifetime of angular momentum, and show superfluidity through the quenching of the moment of inertia. (author)

Gas dynamic lasers

International Nuclear Information System (INIS)

Hill, R.J.; Jewell, N.T.

1975-01-01

In a high powered laser system it is proposed that combustion gases be bled off from a gas turbine engine and their composition adjusted by burning extra fuel in the bleed gases or adding extra substances. Suitable aerodynamic expansion produces a population inversion resulting in laser action in the CO 2 species. Alternatively, bleed gases may be taken from the high pressure compressor of the gas turbine engine and an appropriate fuel burned therein. If required, other adjustments may also be made to the composition and the resulting gaseous mixture subjected to aerodynamic expansion to induce laser action as before. (auth)

Plasma excitation processes in flue gas simulated with Monte Carlo electron dynamics

Energy Technology Data Exchange (ETDEWEB)

Tas, M.A.; Veldhuizen, E.M. van; Rutgers, W.R. [Eindhoven University of Technology (Netherlands). Div. of Electrical Energy Systems

1997-06-07

The excitation of gas molecules in flue gas by electron impact is calculated with a Monte Carlo (MC) algorithm for electron dynamics in partially ionized gases. The MC algorithm is straightforward for any mixture of molecules for which cross sections are available. Electron drift is simulated in the first case for homogeneous electric fields and in the second case for secondary electrons which are produced by electron-beam irradiation. The electron energy distribution function {epsilon}-bar{sub {theta}}, V-bar{sub d}, {lambda}-bar, the energy branching and the rate of excitation are calculated for standard gas mixtures of Ar-N{sub 2}, O{sub 2} and H{sub 2}O. These fundamental process parameters are needed for the study of reactions to remove NO{sub x} from flue gas. The calculated results indicate that the production of highly excited molecules in the high electric field of a streamer corona discharge has an efficiency similar to that of electron-beam irradiation. (author)

Quantum versus classical statistical dynamics of an ultracold Bose gas

International Nuclear Information System (INIS)

Berges, Juergen; Gasenzer, Thomas

2007-01-01

We investigate the conditions under which quantum fluctuations are relevant for the quantitative interpretation of experiments with ultracold Bose gases. This requires to go beyond the description in terms of the Gross-Pitaevskii and Hartree-Fock-Bogoliubov mean-field theories, which can be obtained as classical (statistical) field-theory approximations of the quantum many-body problem. We employ functional-integral techniques based on the two-particle irreducible (2PI) effective action. The role of quantum fluctuations is studied within the nonperturbative 2PI 1/N expansion to next-to-leading order. At this accuracy level memory integrals enter the dynamic equations, which differ for quantum and classical statistical descriptions. This can be used to obtain a classicality condition for the many-body dynamics. We exemplify this condition by studying the nonequilibrium evolution of a one-dimensional Bose gas of sodium atoms, and discuss some distinctive properties of quantum versus classical statistical dynamics

Hibernation and gas exchange.

Science.gov (United States)

Milsom, William K; Jackson, Donald C

2011-01-01

Hibernation in endotherms and ectotherms is characterized by an energy-conserving metabolic depression due to low body temperatures and poorly understood temperature-independent mechanisms. Rates of gas exchange are correspondly reduced. In hibernating mammals, ventilation falls even more than metabolic rate leading to a relative respiratory acidosis that may contribute to metabolic depression. Breathing in some mammals becomes episodic and in some small mammals significant apneic gas exchange may occur by passive diffusion via airways or skin. In ectothermic vertebrates, extrapulmonary gas exchange predominates and in reptiles and amphibians hibernating underwater accounts for all gas exchange. In aerated water diffusive exchange permits amphibians and many species of turtles to remain fully aerobic, but hypoxic conditions can challenge many of these animals. Oxygen uptake into blood in both endotherms and ectotherms is enhanced by increased affinity of hemoglobin for O₂ at low temperature. Regulation of gas exchange in hibernating mammals is predominately linked to CO₂/pH, and in episodic breathers, control is principally directed at the duration of the apneic period. Control in submerged hibernating ectotherms is poorly understood, although skin-diffusing capacity may increase under hypoxic conditions. In aerated water blood pH of frogs and turtles either adheres to alphastat regulation (pH ∼8.0) or may even exhibit respiratory alkalosis. Arousal in hibernating mammals leads to restoration of euthermic temperature, metabolic rate, and gas exchange and occurs periodically even as ambient temperatures remain low, whereas body temperature, metabolic rate, and gas exchange of hibernating ectotherms are tightly linked to ambient temperature. © 2011 American Physiological Society.

Numerical studies of neon gas-puff Z-pinch dynamic processes

International Nuclear Information System (INIS)

Ning Cheng; Yang Zhenhua; Ding Ning

2003-01-01

Dynamic processes of neon gas-puff Z-pinch are studied numerically in this paper. A high temperature plasma with a high density can be generated in the process. Based on some physical analysis and assumption, a set of equations of one-dimensional Lagrangian radiation magneto-hydrodynamic (MHD) and its code are developed to solve the problem. Spatio-temporal distributions of plasma parameters in the processes are obtained, and their dynamic variations show that the major results are self-consistent. The duration for the plasma pinched to centre, as well as the width and the total energy of the x-ray pulse caused by the Z-pinch are in reasonable agreement with experimental results of GAMBLE-II. A zipping effect is also clearly shown in the simulation

The diversity of the effects of sulfur mustard gas inhalation on respiratory system 10 years after a single, heavy exposure: analysis of 197 cases.

Science.gov (United States)

Emad, A; Rezaian, G R

1997-09-01

To find out the late pulmonary sequelae of sulfur mustard gas inhalation in 197 veterans, 10 years after their exposure. Cross-sectional clinical study. University hospital. One hundred ninety-seven veterans with a single, heavy exposure to sulfur mustard gas in 1986 and 86 nonexposed veterans as their control group. Pulmonary function tests, carbon monoxide diffusion capacity, bronchoscopy, and high-resolution CT of the chest were performed in all patients. Transbronchial lung biopsy was done in 24 suspected cases of pulmonary fibrosis. Asthma was diagnosed in 21 (10.65%), chronic bronchitis in 116 (58.88%), bronchiectasis in 17 (8.62%), airway narrowing due to searing or granulation tissue in 19 (9.64%), and pulmonary fibrosis in 24 (12.18%) cases. None of these were found among the control group except for a single case of chronic bronchitis. Although the respiratory symptoms of an acute sulfur mustard gas inhalation are usually transient and nonspecific, it can lead to the development of a series of chronic destructive pulmonary sequelae in such cases.

Investigation of interface boundary occurring during cold gas-dynamic spraying of metallic particles

CERN Document Server

Bolesta, A V; Sharafutdinov, M R; Tolochko, B P

2001-01-01

An interface boundary occurring during cold gas dynamic spraying of aluminum particles on a nickel substrate has been studied by the method of X-ray grazing diffraction. Presence of boundary phase of the intermetallic compound Ni sub 3 Al was found.

The Experimental Study of Dynamics of Scaled Gas-Filled Bubble Collapse in Liquid

Science.gov (United States)

Pavlenko, Alexander

2011-06-01

The article provides results of analyzing special features of the single-bubble sonoluminescence, developing the special apparatus to investigate this phenomenon on a larger-scale basis. Certain very important effects of high energy density physics, i.e. liquid compressibility, shock-wave formation under the collapse of the gas cavity in liquid, shock-wave focusing in the gas-filled cavity, occurrence of hot dense plasma in the focusing area, and high-temperature radiation yield are observed in this phenomenon. Specificity of the process is conditioned by the ``ideal'' preparation and sphericity of the gas-and-liquid contact boundary what makes the collapse process efficient due to the reduced influence of hydrodynamic instabilities. Results of experimental investigations; results of developing the facilities, description of methods used to register parameters of facilities and the system under consideration; analytical estimates how gas-filled bubbles evolve in liquid with the regard for scale effects; results of preliminary 1-D gas dynamic calculations of the gas bubble evolution are presented. The work supported by ISTC Project #2116.

Discontinuous gas exchange, water loss, and metabolism in Protaetia cretica (Cetoniinae, Scarabaeidae).

Science.gov (United States)

Matthews, Philip G D; White, Craig R

2012-01-01

Insects are at high risk of desiccation because of their small size, high surface-area-to-volume ratio, and air-filled tracheal system that ramifies throughout their bodies to transport O(2) and CO(2) to and from respiring cells. Although the tracheal system offers a high-conductance pathway for the movement of respiratory gases, it has the unintended consequence of allowing respiratory transpiration to the atmosphere. When resting, many species exchange respiratory gases discontinuously, and an early hypothesis for the origin of these discontinuous gas exchange cycles (DGCs) is that they serve to reduce respiratory water loss. In this study, we test this "hygric" hypothesis by comparing rates of CO(2) exchange and water loss among flower beetles Protaetia cretica (Cetoniinae, Scarabaeidae) breathing either continuously or discontinuously. We show that, consistent with the expectations of the hygric hypothesis, rates of total water loss are higher during continuous gas exchange than during discontinuous gas exchange and that the ratio of respiratory water loss to CO(2) exchange is lower during discontinuous gas exchange. This conclusion is in agreement with other studies of beetles and cockroaches that also support the hygric hypothesis. However, this result does not exclude other adaptive hypotheses supported by work on ants and moth pupae. This ambiguity may arise because there are multiple independent evolutionary origins of DGCs and no single adaptive function underlying their genesis. Alternatively, the observed reduction in water loss during DGCs may be a side effect of a nonadaptive gas exchange pattern that is elicited during periods of inactivity.

Topological phase transition in the quench dynamics of a one-dimensional Fermi gas

OpenAIRE

Wang, Pei; Yi, Wei; Xianlong, Gao

2014-01-01

We study the quench dynamics of a one-dimensional ultracold Fermi gas in an optical lattice potential with synthetic spin-orbit coupling. At equilibrium, the ground state of the system can undergo a topological phase transition and become a topological superfluid with Majorana edge states. As the interaction is quenched near the topological phase boundary, we identify an interesting dynamical phase transition of the quenched state in the long-time limit, characterized by an abrupt change of t...

Set-Up and Validation of a Dynamic Solid/Gas Bioreactor

KAUST Repository

Lloyd-Randol, Jennifer D.

2012-05-01

The limited availability of fossil resourses mandates the development of new energy vectors, which is one of the Grand Challenges of the 21st Century [1]. Biocatalytic energy conversion is a promising solution to meet the increased energy demand of industrialized societies. Applications of biocatalysis in the gas-phase are so far limited to production of fine chemicals and pharmaceuticals. However, this technology has the potential for large scale biocatalytic applications [2], e.g. for the formation of novel energy carriers. The so-called solid/gas biocatalysis is defined as the application of a biocatalyst immobilized on solid-phase support acting on gaseous substrates [3]. This process combines the advantages of bio-catalysis (green chemistry, mild reaction conditions, high specicity & selectivity) and heterogeneous dynamic gas-phase processes (low diffusion limitation, high conversion, simple scale-up). This work presents the modifications of a PID Microactivity Reference reactor in order to make it suitable for solid/gas biocatalysis. The reactor design requirements are based on previously published laboratory scale solid/gas systems with a feed of saturated vapors [4]. These vapors are produced in saturation flasks, which were designed and optimized during this project. Other modifications included relocation of the gas mixing chamber, redesigning the location and heating mechanism for the reactor tube, and heating of the outlet gas line. The modified reactor system was verified based on the Candida antarctica lipase B catalyzed transesterication of ethyl acetate with 1-hexanol to hexyl acetate and ethanol and results were compared to liquid-phase model reactions. Products were analyzed on line by a gas chromatograph with a flame ionization detector. C. antarc- tica physisorbed on silica particles produced a 50% conversion of hexanol at 40 C in the gas-phase. A commercial immobilized lipase from Iris Biotech produced 99% and 97% conversions of hexanol in

Nonlinear dynamics of cycle-to-cycle combustion variations in a lean-burn natural gas engine

Energy Technology Data Exchange (ETDEWEB)

Li Guoxiu [School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044 (China)], E-mail: gxli@bjtu.edu.cn; Yao Baofeng [School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044 (China)

2008-04-15

Temporal dynamics of the combustion process in a lean-burn natural gas engine was studied by the analysis of time series of consecutive experimental in-cylinder pressure data in this work. Methods borrowed to the nonlinear dynamical system theory were applied to analyze the in-cylinder pressure time series under operating conditions with different equivalence ratio. Phase spaces were reconstructed from the in-cylinder pressure time series and Poincare section calculated from each phase space. Poincare sections show that the in-cylinder combustion process involves chaotic behavior. Furthermore, return maps plotted from time series of indicated mean effective pressure show that both nonlinear deterministic components and stochastic components are involved in the dynamics of cycle-to-cycle combustion variations in the lean burn natural gas engine. There is a transition from stochastic behavior to noisy nonlinear determinism as equivalence ratio decreases from near stoichiometric to very lean conditions.

Nonlinear dynamics of cycle-to-cycle combustion variations in a lean-burn natural gas engine

International Nuclear Information System (INIS)

Li Guoxiu; Yao Baofeng

2008-01-01

Temporal dynamics of the combustion process in a lean-burn natural gas engine was studied by the analysis of time series of consecutive experimental in-cylinder pressure data in this work. Methods borrowed to the nonlinear dynamical system theory were applied to analyze the in-cylinder pressure time series under operating conditions with different equivalence ratio. Phase spaces were reconstructed from the in-cylinder pressure time series and Poincare section calculated from each phase space. Poincare sections show that the in-cylinder combustion process involves chaotic behavior. Furthermore, return maps plotted from time series of indicated mean effective pressure show that both nonlinear deterministic components and stochastic components are involved in the dynamics of cycle-to-cycle combustion variations in the lean burn natural gas engine. There is a transition from stochastic behavior to noisy nonlinear determinism as equivalence ratio decreases from near stoichiometric to very lean conditions

Economics and ethics of paediatric respiratory extra corporeal life support.

Science.gov (United States)

Callaghan, M; Doyle, Y; O'Hare, B; Healy, M; Nölke, L

2013-09-01

Extra corporeal membrane oxygenation (ECMO) is a form of life support, which facilitates gas exchange outside the body via an oxygenator and a centrifugal pumping system. A paediatric cardiac ECMO programme was established in 2005 at Our Lady's Children's Hospital, Crumlin (OLCHC) and to date 75 patients have received ECMO, the majority being post operative cardiac patients. The outcome data compares favourably with international figures. ECMO has been most successful in the treatment of newborn infants with life threatening respiratory failure from conditions such as meconium aspiration, respiratory distress syndrome and respiratory infections. There is no formal paediatric respiratory ECMO programme at OLCHC, or anywhere else in Ireland. Currently, neonates requiring respiratory ECMO are transferred to centres in Sweden or the UK at an average cost of 133,000 Euros/infant, funded by the Health Service Executive E112 treatment abroad scheme. There is considerable morbidity associated with the transfer of critically ill infants, as well as significant psycho-social impact on families. OLCHC is not funded to provide respiratory ECMO, although the equipment and expertise required are similar to cardiac ECMO and are currently in place. The average cost of an ECMO run at OLCHC is 65,000 Euros. There is now a strong argument for a fully funded single national cardiac and respiratory paediatric ECMO centre, similar to that for adult patients.

STUDY OF GAS SEPARATION PROCESS BY DYNAMIC ADSORPTION IN FIXED BED

Directory of Open Access Journals (Sweden)

Ioan Solomon

2010-10-01

Full Text Available An experimental study of mass transfer at gas separation by dynamic adsorption in fixed bed of impregnated silica gel is presented in this work. By means of a mathematical model based on constants and coefficient easy to evaluate, the distributions of adsorbate concentration in gas and solid phases were determined as a function of time and throughout the height of the fixed bed, under isothermal conditions.With this aim, water vapors from air were adsorbed in a fixed bed of impregnated silica gel. The values of the volumetric mass transfer coefficient, Kv, were determined experimentally at several values of air superficial velocity, an air relative humidity of 69�20at 38 °C. The influence of the gas flow velocity and initial water concentration in adsorbent on the distribution of water concentration in both phases was established as a function of time and throughout the height of the fixed bed. The results obtained allow one to determination of the local adsorption rate.

Protein structural dynamics at the gas/water interface examined by hydrogen exchange mass spectrometry.

Science.gov (United States)

Xiao, Yiming; Konermann, Lars

2015-08-01

Gas/water interfaces (such as air bubbles or foam) are detrimental to the stability of proteins, often causing aggregation. This represents a potential problem for industrial processes, for example, the production and handling of protein drugs. Proteins possess surfactant-like properties, resulting in a high affinity for gas/water interfaces. The tendency of previously buried nonpolar residues to maximize contact with the gas phase can cause significant structural distortion. Most earlier studies in this area employed spectroscopic tools that could only provide limited information. Here we use hydrogen/deuterium exchange (HDX) mass spectrometry (MS) for probing the conformational dynamics of the model protein myoglobin (Mb) in the presence of N(2) bubbles. HDX/MS relies on the principle that unfolded and/or highly dynamic regions undergo faster deuteration than tightly folded segments. In bubble-free solution Mb displays EX2 behavior, reflecting the occurrence of short-lived excursions to partially unfolded conformers. A dramatically different behavior is seen in the presence of N(2) bubbles; EX2 dynamics still take place, but in addition the protein shows EX1 behavior. The latter results from interconversion of the native state with conformers that are globally unfolded and long-lived. These unfolded species likely correspond to Mb that is adsorbed to the surface of gas bubbles. N(2) sparging also induces aggregation. To explain the observed behavior we propose a simple model, that is, "semi-unfolded" ↔ "native" ↔ "globally unfolded" → "aggregated". This model quantitatively reproduces the experimentally observed kinetics. To the best of our knowledge, the current study marks the first exploration of surface denaturation phenomena by HDX/MS. © 2015 The Protein Society.

Automotive exhaust gas conversion: from elementary step kinetics to prediction of emission dynamics

NARCIS (Netherlands)

Hoebink, J.H.B.J.; Harmsen, J.M.A.; Balenovic, M.; Backx, A.C.P.M.; Schouten, J.C.

2001-01-01

Elementary step based kinetics show a high added value to describe the performance of catalytic exhaust gas converters under dynamic conditions, as demonstrated with a Euro test cycle. Combination of such kinetic models for individual global reactions covers the mutual interactions via common

Future evolution of the liberalised European gas market: Simulation results with a dynamic model

Energy Technology Data Exchange (ETDEWEB)

Lise, Wietze [IBS Research and Consultancy, Aga Han, Agahamami Cadessi 1/6, Cihangir, 34433 Beyoglu, Istanbul (Turkey); Energy Markets and International Environmental Policy group, ECN Policy Studies, Energy Research Centre of the Netherlands, Amsterdam (Netherlands); Hobbs, Benjamin F. [Department of Geography and Environmental Engineering, The Johns Hopkins University, Ames Hall 313, 3400 North Charles Street, Baltimore, MD 21218 (United States)

2008-07-15

Strategic behaviour by gas producers is likely to affect future gas prices and investments in the European Union (EU). To analyse this issue, a computational game theoretic model is presented that is based on a recursive-dynamic formulation. This model addresses interactions among demand, supply, pipeline and liquefied natural gas (LNG) transport, storage and investments in the natural gas market over the period 2005-2030. Three market scenarios are formulated to study the impact of producer market power. In addition, tradeoffs among investments in pipelines, LNG liquefaction and regasification facilities, and storage are explored. The model runs indicate that LNG can effectively compete with pipelines in the near future. Further, significant decreases in Cournot prices between 2005 and 2010 indicate that near-term investments in EU gas transport capacity are likely to diminish market power by making markets more accessible. (author)

Future evolution of the liberalised European gas market: Simulation results with a dynamic model

International Nuclear Information System (INIS)

Lise, Wietze; Hobbs, Benjamin F.

2008-01-01

Strategic behaviour by gas producers is likely to affect future gas prices and investments in the European Union (EU). To analyse this issue, a computational game theoretic model is presented that is based on a recursive-dynamic formulation. This model addresses interactions among demand, supply, pipeline and liquefied natural gas (LNG) transport, storage and investments in the natural gas market over the period 2005-2030. Three market scenarios are formulated to study the impact of producer market power. In addition, tradeoffs among investments in pipelines, LNG liquefaction and regasification facilities, and storage are explored. The model runs indicate that LNG can effectively compete with pipelines in the near future. Further, significant decreases in Cournot prices between 2005 and 2010 indicate that near-term investments in EU gas transport capacity are likely to diminish market power by making markets more accessible. (author)

Dynamics of exciplex formation in rare gas media

Energy Technology Data Exchange (ETDEWEB)

Rojas-Lorenzo, German, E-mail: grojas37@gmail.com [Departamento de Fisica General y Matematicas, Instituto Superior de Tecnologias y Ciencias Aplicadas, La Habana (Cuba)] [Instituto de Fisica Fundamental, Consejo Superior de Investigaciones Cientificas, Serrano 123, 28006 Madrid (Spain); Rubayo-Soneira, Jesus [Departamento de Fisica General y Matematicas, Instituto Superior de Tecnologias y Ciencias Aplicadas, La Habana (Cuba); Alberti, Sebastian Fernandez [Centro de Estudios e Investigaciones, Universidad Nacional de Quilmes, Roque Saenz Pena 180, Bernal B1876BXD (Argentina)

2009-07-30

A hopping-surface algorithm has been used to simulate the dynamics induced in rare gas matrices due to the photoexcitation ({sup 1}S{sub 0} {yields} {sup 3}P{sub 1}) of atomic mercury embedded in them. Especially, the study of the dynamics of an exciplex formation in a model system consisting of solid xenon doped with atomic mercury. The process starts upon the photoexcitation of the Hg atom to its {sup 3}P{sub 1} electronic excited state. Diatomics-in-Molecule approach has been used for constructing the adiabatic potential surfaces. In all trajectories we show that a triatomic Xe-Hg{sup *}-Xe complex is formed, but in two conformations: bent and linear. The mechanisms leading to the formation of one or the other are identified. Mainly, are noted the thermal fluctuations of the Hg impurity and the shape of the potential surfaces. Furthermore, we show that non-radiative intrastate relaxation occurs via a conical intersection between the excited state surfaces. The simulated spectra are in very good agreement with the experimental data.

Dynamic performance of power generation systems for off-shore oil and gas platforms

DEFF Research Database (Denmark)

Pierobon, Leonardo; Breuhaus, Peter; Haglind, Fredrik

2014-01-01

%) arises on the prediction of the rotational speed of the high pressure shaft, while the largest deviation (average relative error ~20%) occurs in the evaluation of the pressure at the outlet of the low pressure turbine. As waste heat recovery units (e.g. organic Rankine cycles) are likely...... to be implemented in future off-shore platforms, the proposed model may serve in the design phase for a preliminary assessment of the dynamic response of the power generation system and to evaluate if requirements such as minimum and maximum frequency during transient operation and the recovery time are satisfied......On off-shore oil and gas platforms two or more gas turbines typically support the electrical demand on site by operating as a stand-alone (island) power system. As reliability and availability are major concerns during operation, the dynamic performance of the power generation system becomes...

Respiratory Changes in Response to Cognitive Load: A Systematic Review.

Science.gov (United States)

Grassmann, Mariel; Vlemincx, Elke; von Leupoldt, Andreas; Mittelstädt, Justin M; Van den Bergh, Omer

2016-01-01

When people focus attention or carry out a demanding task, their breathing changes. But which parameters of respiration vary exactly and can respiration reliably be used as an index of cognitive load? These questions are addressed in the present systematic review of empirical studies investigating respiratory behavior in response to cognitive load. Most reviewed studies were restricted to time and volume parameters while less established, yet meaningful parameters such as respiratory variability have rarely been investigated. The available results show that respiratory behavior generally reflects cognitive processing and that distinct parameters differ in sensitivity: While mentally demanding episodes are clearly marked by faster breathing and higher minute ventilation, respiratory amplitude appears to remain rather stable. The present findings further indicate that total variability in respiratory rate is not systematically affected by cognitive load whereas the correlated fraction decreases. In addition, we found that cognitive load may lead to overbreathing as indicated by decreased end-tidal CO2 but is also accompanied by elevated oxygen consumption and CO2 release. However, additional research is needed to validate the findings on respiratory variability and gas exchange measures. We conclude by outlining recommendations for future research to increase the current understanding of respiration under cognitive load.

Dynamic Contraction of the Positive Column of a Self-Sustained Glow Discharge in Molecular Gas Flow

Science.gov (United States)

Shneider, Mikhail

2014-10-01

Contraction of the gas discharge, when current contracts from a significant volume of weakly ionized plasma into a thin arc channel, was attracted attention of scientists for more than a century. Studies of the contraction (also called constriction) mechanisms, besides carrying interesting science, are of practical importance, especially when contraction should be prevented. A set of time-dependent two-dimensional equations for the non-equilibrium weakly-ionized nitrogen/ air plasma is formulated. The process is described by a set of time-dependent continuity equations for the electrons, positive and negative ions; gas and vibrational temperature; by taking into account the convective heat and plasma losses by the transverse flux. Transition from the uniform to contracted state was analyzed. It was shown that such transition experiences a hysteresis, and that the critical current of the transition increases when the pressure (gas density) drops. Possible coexistence of the contracted and uniform state of the plasma in the discharge where the current flows along the density gradient of the background gas was discussed. In this talk the problems related to the dynamic contraction of the current channel inside a quasineutral positive column of a self-sustained glow discharge in molecular gas in a rectangular duct with convection cooling will be discussed. Study presented in this talk was stimulated by the fact that there are large number of experiments on the dynamic contraction of a glow discharge in nitrogen and air flows and a many of possible applications. Similar processes play a role in the powerful gas-discharge lasers. In addition, the problem of dynamic contraction in the large volume of non-equilibrium weakly ionized plasma is closely related to the problem of streamer to leader transitions in lightning and blue jets.

Study of Influencing Factors of Dynamic Measurements Based on SnO2 Gas Sensor

Directory of Open Access Journals (Sweden)

Jinhuai Liu

2004-08-01

Full Text Available Abstract: The gas-sensing behaviour based on a dynamic measurement method of a single SnO2 gas sensor was investigated by comparison with the static measurement. The influencing factors of nonlinear response such as modulation temperature, duty ratio, heating waveform (rectangular, sinusoidal, saw-tooth, pulse, etc. were also studied. Experimental data showed that temperature was the most essential factor because the changes of frequency and heating waveform could result in the changes of temperature essentially.

Dosimetry of the respiratory tract

International Nuclear Information System (INIS)

Roy, M.

1996-01-01

A new dosimetric model of the human respiratory tract has been recently recommended by the International Commission on Radiological Protection, in ICRP Publication 66. This model was intended to update the previous lung model of the Task Group on Lung Dynamics that was adopted by ICRP in Publication 30. With this aim, extensive reviews of the available knowledge were made for anatomy and physiology of the respiratory tract and for deposition, clearance and biological effects of inhaled radionuclides. Finally, expanded dosimetry requirements resulted in a widely different approach from the former model. The main features of the new model are the followings: instead of calculating the average dose to the total mass of blood filled lung, the model takes account of differences in radiosensitivity of the venous respiratory tract tissues. It applies not only to adult workers but also to all members of the population, and provides reference values for children aged 3 months, 1, 5, 10, and 15 years, and adults. Deposition modelling of airborne gases and aerosols associates age dependent breathing rates, airway dimensions and physical activity, to particle size, density and chemical form of inhaled material. Clearance results of competition between mechanical transport clearance and absorption to blood. At each step of the calculation, adjustment guidance is provided to account for use of exact values of particle sizes and specific dissolution rates of inhaled material in order to calculate their own parameter of retention in the airways, and to assess accurately doses to the respiratory tract. Possible influence of smoking, of respiratory tract diseases and of eventual exposure to airborne toxicants is also addressed. (author)

Gas dynamics an introduction with examples from astrophysics and geophysics

CERN Document Server

Achterberg, Abraham

2016-01-01

This book lays the foundations of gas- and fluid dynamics. The basic equations are developed from first principles, building on the (assumed) knowledge of Classical Mechanics. This leads to the discussion of the mathematical properties of flows, conservation laws, perturbation analysis, waves and shocks. Most of the discussion centers on ideal (frictionless) fluids and gases. Viscous flows are discussed when considering flows around obstacles and shocks. Many of the examples used to illustrate various processes come from astrophysics and geophysical phenomena.

Investigating parameters participating in the infant respiratory control system attractor.

Science.gov (United States)

Terrill, Philip I; Wilson, Stephen J; Suresh, Sadasivam; Cooper, David M; Dakin, Carolyn

2008-01-01

Theoretically, any participating parameter in a non-linear system represents the dynamics of the whole system. Taken's time delay embedding theory provides the fundamental basis for allowing non-linear analysis to be performed on physiological, time-series data. In practice, only one measurable parameter is required to be measured to convey an accurate representation of the system dynamics. In this paper, the infant respiratory control system is represented using three variables-a digitally sampled respiratory inductive plethysmography waveform, and the derived parameters tidal volume and inter-breath interval time series data. For 14 healthy infants, these data streams were analysed using recurrence plot analysis across one night of sleep. The measured attractor size of these variables followed the same qualitative trends across the nights study. Results suggest that the attractor size measures of the derived IBI and tidal volume are representative surrogates for the raw respiratory waveform. The extent to which the relative attractor sizes of IBI and tidal volume remain constant through changing sleep state could potentially be used to quantify pathology, or maturation of breathing control.

On a non-local gas dynamics like integrable hierarchy

International Nuclear Information System (INIS)

Brunelli, Jose Carlos; Das, Ashok

2004-01-01

We study a new hierarchy of equations derived from the system of isentropic gas dynamics equations where the pressure is a non-local function of the density. We show that the hierarchy of equations is integrable. We construct the two compatible Hamiltonian structures and show that the first structure has three distinct Casimirs while the second has one. The existence of Casimirs allows us to extend the flows to local ones. We construct an infinite series of commuting local Hamiltonians as well as three infinite series (related to the three Casimirs) of non-local charges. We discuss the zero curvature formulation of the system where we obtain a simple expression for the non-local conserved charges, which also clarifies the existence of the three series from a Lie algebraic point of view. We point out that the non-local hierarchy of Hunter-Zheng equations can be obtained from our non-local flows when the dynamical variables are properly constrained. (author)

Acute respiratory alkalosis occurring after endoscopic third ventriculostomy -A case report-.

Science.gov (United States)

Sung, Hui-Jin; Sohn, Ju-Tae; Kim, Jae-Gak; Shin, Il-Woo; Ok, Seong-Ho; Lee, Heon-Keun; Chung, Young-Kyun

2010-12-01

An endoscopic third ventriculostomy was performed in a 55-year-old man with an obstructive hydrocephalus due to aqueductal stenosis. The vital signs and laboratory studies upon admission were within the normal limits. Anesthesia was maintained with nitrous oxide in oxygen and 6% desflurane. The patient received irrigation with approximately 3,000 ml normal saline during the procedure. Anesthesia and operation were uneventful. However, he developed postoperative hyperventilation in the recovery room, and arterial blood gas analysis revealed acute respiratory alkalosis. We report a rare respiratory alkalosis that occurred after an endoscopic third ventriculostomy.

Computational Models and Emergent Properties of Respiratory Neural Networks

Science.gov (United States)

Lindsey, Bruce G.; Rybak, Ilya A.; Smith, Jeffrey C.

2012-01-01

Computational models of the neural control system for breathing in mammals provide a theoretical and computational framework bringing together experimental data obtained from different animal preparations under various experimental conditions. Many of these models were developed in parallel and iteratively with experimental studies and provided predictions guiding new experiments. This data-driven modeling approach has advanced our understanding of respiratory network architecture and neural mechanisms underlying generation of the respiratory rhythm and pattern, including their functional reorganization under different physiological conditions. Models reviewed here vary in neurobiological details and computational complexity and span multiple spatiotemporal scales of respiratory control mechanisms. Recent models describe interacting populations of respiratory neurons spatially distributed within the Bötzinger and pre-Bötzinger complexes and rostral ventrolateral medulla that contain core circuits of the respiratory central pattern generator (CPG). Network interactions within these circuits along with intrinsic rhythmogenic properties of neurons form a hierarchy of multiple rhythm generation mechanisms. The functional expression of these mechanisms is controlled by input drives from other brainstem components, including the retrotrapezoid nucleus and pons, which regulate the dynamic behavior of the core circuitry. The emerging view is that the brainstem respiratory network has rhythmogenic capabilities at multiple levels of circuit organization. This allows flexible, state-dependent expression of different neural pattern-generation mechanisms under various physiological conditions, enabling a wide repertoire of respiratory behaviors. Some models consider control of the respiratory CPG by pulmonary feedback and network reconfiguration during defensive behaviors such as cough. Future directions in modeling of the respiratory CPG are considered. PMID:23687564

Respiratory Mechanics and Gas Exchange: The Effect of Surfactants

Science.gov (United States)

Jbaily, Abdulrahman; Szeri, Andrew J.

2017-11-01

The purpose of the lung is to exchange gases, primarily oxygen and carbon dioxide, between the atmosphere and the circulatory system. To enable this exchange, the airways in the lungs terminate in some 300 million alveoli that provide adequate surface area for transport. During breathing, work must be done to stretch various tissues to accommodate a greater volume of gas. Considerable work must also be done to expand the liquid lining (hypophase) that coats the interior surfaces of the alveoli. This is enabled by a surface active lipo-protein complex, known as pulmonary surfactant, that modifies the surface tension at the hypophase-air interface. Surfactants also serve as physical barriers that modify the rate of gas transfer across interfaces. We develop a mathematical model to study the action of pulmonary surfactant and its determinative contributions to breathing. The model is used to explore the influence of surfactants on alveolar mechanics and on gas exchange: it relates the work of respiration at the level of the alveolus to the gas exchange rate through the changing influence of pulmonary surfactant over the breathing cycle. This work is motivated by a need to develop improved surfactant replacement therapies to treat serious medical conditions.

3-D Model of the Human Respiratory System

Science.gov (United States)

The U.S. EPA’s Office of Research and Development (ORD) has developed a 3-D computational fluid dynamics (CFD) model of the human respiratory system that allows for the simulation of particulate based contaminant deposition and clearance, while being adaptable for age, ethnicity,...

Sources of Indoor Air Pollution and Respiratory Health in Preschool Children

International Nuclear Information System (INIS)

Leonarte, V.F.; Ballester, F.; Leonarte, V.F.; Ballester, F.; Tenias, J.M.; Tenias, J.M.

2010-01-01

We carried out bibliographic searches in Pub Med and Embase.com for the period from 1996 to 2008 with the aim of reviewing the scientific literature on the relationship between various sources of indoor air pollution and the respiratory health of children under the age of five. Those studies that included adjusted correlation measurements for the most important confounding variables and which had an adequate population size were considered to be more relevant. The results concerning the relationship between gas energy sources and children's respiratory health were heterogeneous. Indoor air pollution from biomass combustion in the poorest countries was found to be an important risk factor for lower respiratory tract infections. Solvents involved in redecorating, DY work, painting, and so forth, were found to be related to an increased risk for general respiratory problems. The distribution of papers depending on the pollution source showed a clear relationship with life-style and the level of development.

Sources of Indoor Air Pollution and Respiratory Health in Preschool Children

Directory of Open Access Journals (Sweden)

Virginia Fuentes-Leonarte

2009-01-01

Full Text Available We carried out bibliographic searches in PubMed and Embase.com for the period from 1996 to 2008 with the aim of reviewing the scientific literature on the relationship between various sources of indoor air pollution and the respiratory health of children under the age of five. Those studies that included adjusted correlation measurements for the most important confounding variables and which had an adequate population size were considered to be more relevant. The results concerning the relationship between gas energy sources and children's respiratory health were heterogeneous. Indoor air pollution from biomass combustion in the poorest countries was found to be an important risk factor for lower respiratory tract infections. Solvents involved in redecorating, DYI work, painting, and so forth, were found to be related to an increased risk for general respiratory problems. The distribution of papers depending on the pollution source showed a clear relationship with life-style and the level of development.

Evaluation of the new respiratory gating system

Science.gov (United States)

Shi, Chengyu; Tang, Xiaoli; Chan, Maria

2018-01-01

Objective The newly released Respiratory Gating for Scanners (RGSC; Varian Medical Systems, Palo Alto, CA, USA) system has limited existing quality assurance (QA) protocols and pertinent publications. Herein, we report our experiences of the RGSC system acceptance and QA. Methods The RGSC system integration was tested with peripheral equipment, spatial reproducibility, and dynamic localization accuracy for regular and irregular breathing patterns, respectively. A QUASAR Respiratory Motion Phantom and a mathematical fitting method were used for data acquisition and analysis. Results The results showed that the RGSC system could accurately measure regular motion periods of 3–10 s. For irregular breathing patterns, differences from the existing Real-time Position Management (RPM; Varian Medical Systems, Palo Alto, CA) system were observed. For dynamic localization measurements, the RGSC system showed 76% agreement with the programmed test data within ±5% tolerance in terms of fitting period. As s comparison, the RPM system showed 66% agreement within ±5% tolerance, and 65% for the RGSC versus RPM measurements. Conclusions New functions and positioning accuracy improve the RGSC system’s ability to achieve higher dynamic treatment precision. A 4D phantom is helpful for the QA tests. Further investigation is required for the whole RGSC system performance QA. PMID:29722356

Computational fluid dynamics modeling of Bacillus anthracis spore deposition in rabbit and human respiratory airways

Energy Technology Data Exchange (ETDEWEB)

Kabilan, S.; Suffield, S. R.; Recknagle, K. P.; Jacob, R. E.; Einstein, D. R.; Kuprat, A. P.; Carson, J. P.; Colby, S. M.; Saunders, J. H.; Hines, S. A.; Teeguarden, J. G.; Straub, T. M.; Moe, M.; Taft, S. C.; Corley, R. A.

2016-09-01

Three-dimensional computational fluid dynamics and Lagrangian particle deposition models were developed to compare the deposition of aerosolized Bacillus anthracis spores in the respiratory airways of a human with that of the rabbit, a species commonly used in the study of anthrax disease. The respiratory airway geometries for each species were derived respectively from computed tomography (CT) and µCT images. Both models encompassed airways that extended from the external nose to the lung with a total of 272 outlets in the human model and 2878 outlets in the rabbit model. All simulations of spore deposition were conducted under transient, inhalation–exhalation breathing conditions using average species-specific minute volumes. Two different exposure scenarios were modeled in the rabbit based upon experimental inhalation studies. For comparison, human simulations were conducted at the highest exposure concentration used during the rabbit experimental exposures. Results demonstrated that regional spore deposition patterns were sensitive to airway geometry and ventilation profiles. Due to the complex airway geometries in the rabbit nose, higher spore deposition efficiency was predicted in the nasal sinus compared to the human at the same air concentration of anthrax spores. In contrast, higher spore deposition was predicted in the lower conducting airways of the human compared to the rabbit lung due to differences in airway branching pattern. This information can be used to refine published and ongoing biokinetic models of inhalation anthrax spore exposures, which currently estimate deposited spore concentrations based solely upon exposure concentrations and inhaled doses that do not factor in species-specific anatomy and physiology for deposition.

Computational Fluid Dynamics Modeling of Bacillus anthracis Spore Deposition in Rabbit and Human Respiratory Airways

Energy Technology Data Exchange (ETDEWEB)

Kabilan, Senthil; Suffield, Sarah R.; Recknagle, Kurtis P.; Jacob, Rick E.; Einstein, Daniel R.; Kuprat, Andrew P.; Carson, James P.; Colby, Sean M.; Saunders, James H.; Hines, Stephanie; Teeguarden, Justin G.; Straub, Tim M.; Moe, M.; Taft, Sarah; Corley, Richard A.

2016-09-30

Three-dimensional computational fluid dynamics and Lagrangian particle deposition models were developed to compare the deposition of aerosolized Bacillus anthracis spores in the respiratory airways of a human with that of the rabbit, a species commonly used in the study of anthrax disease. The respiratory airway geometries for each species were derived from computed tomography (CT) or µCT images. Both models encompassed airways that extended from the external nose to the lung with a total of 272 outlets in the human model and 2878 outlets in the rabbit model. All simulations of spore deposition were conducted under transient, inhalation-exhalation breathing conditions using average species-specific minute volumes. The highest exposure concentration was modeled in the rabbit based upon prior acute inhalation studies. For comparison, human simulation was also conducted at the same concentration. Results demonstrated that regional spore deposition patterns were sensitive to airway geometry and ventilation profiles. Due to the complex airway geometries in the rabbit nose, higher spore deposition efficiency was predicted in the upper conducting airways compared to the human at the same air concentration of anthrax spores. As a result, higher particle deposition was predicted in the conducting airways and deep lung of the human compared to the rabbit lung due to differences in airway branching pattern. This information can be used to refine published and ongoing biokinetic models of inhalation anthrax spore exposures, which currently estimate deposited spore concentrations based solely upon exposure concentrations and inhaled doses that do not factor in species-specific anatomy and physiology.

Uncertainty in microscale gas damping: Implications on dynamics of capacitive MEMS switches

International Nuclear Information System (INIS)

Alexeenko, Alina; Chigullapalli, Sruti; Zeng Juan; Guo Xiaohui; Kovacs, Andrew; Peroulis, Dimitrios

2011-01-01

Effects of uncertainties in gas damping models, geometry and mechanical properties on the dynamics of micro-electro-mechanical systems (MEMS) capacitive switch are studied. A sample of typical capacitive switches has been fabricated and characterized at Purdue University. High-fidelity simulations of gas damping on planar microbeams are developed and verified under relevant conditions. This and other gas damping models are then applied to study the dynamics of a single closing event for switches with experimentally measured properties. It has been demonstrated that although all damping models considered predict similar damping quality factor and agree well for predictions of closing time, the models differ by a factor of two and more in predicting the impact velocity and acceleration at contact. Implications of parameter uncertainties on the key reliability-related parameters such as the pull-in voltage, closing time and impact velocity are discussed. A notable effect of uncertainty is that the nominal switch, i.e. the switch with the average properties, does not actuate at the mean actuation voltage. Additionally, the device-to-device variability leads to significant differences in dynamics. For example, the mean impact velocity for switches actuated under the 90%-actuation voltage (about 150 V), i.e. the voltage required to actuate 90% of the sample, is about 129 cm/s and increases to 173 cm/s for the 99%-actuation voltage (of about 173 V). Response surfaces of impact velocity and closing time to five input variables were constructed using the Smolyak sparse grid algorithm. The sensitivity analysis showed that impact velocity is most sensitive to the damping coefficient whereas the closing time is most affected by the geometric parameters such as gap and beam thickness. - Highlights: → We examine stochastic non-linear response of a microsystem switch subject to multiple input uncertainties. → Sample devices have been fabricated and device

Large-scale gas dynamical processes affecting the origin and evolution of gaseous galactic halos

Science.gov (United States)

Shapiro, Paul R.

1991-01-01

Observations of galactic halo gas are consistent with an interpretation in terms of the galactic fountain model in which supernova heated gas in the galactic disk escapes into the halo, radiatively cools and forms clouds which fall back to the disk. The results of a new study of several large-scale gas dynamical effects which are expected to occur in such a model for the origin and evolution of galactic halo gas will be summarized, including the following: (1) nonequilibrium absorption line and emission spectrum diagnostics for radiatively cooling halo gas in our own galaxy, as well the implications of such absorption line diagnostics for the origin of quasar absorption lines in galactic halo clouds of high redshift galaxies; (2) numerical MHD simulations and analytical analysis of large-scale explosions ad superbubbles in the galactic disk and halo; (3) numerical MHD simulations of halo cloud formation by thermal instability, with and without magnetic field; and (4) the effect of the galactic fountain on the galactic dynamo.

Insights into the dynamics of in situ gas hydrate formation and dissociation at the Bush Hill gas hydrate field, Gulf of Mexico

Energy Technology Data Exchange (ETDEWEB)

Solomon, Evan A.; Kastner, Miriam; Robertson, Gretchen; Jannasch, Hans; Weinstein, Yishai

2005-07-01

Four newly designed flux meters called the MOSQUITO (Multiple Orifice Sampler and Quantitative Injection Tracer Observer), capable of measuring fluid flow rates and sampling pore fluid chemistry simultaneously, and two temperature loggers were deployed for 430 days adjacent to the Bush Hill hydrate mound in the northern Gulf of Mexico (GC 185). The main objective of the deployment was to understand how chemistry, temperature, and subsurface hydrology dynamically influence the growth and dissociation of the gas hydrate mound. The flux meters were deployed in a mussel field, in bacterial mats, in a tubeworm field, and at a background site approximately 100 m southwest of the hydrate mound. Results from the longterm chemical monitoring suggest that this system is not in dynamic equilibrium. Gas hydrate actively formed within the mussel field adjacent to the most active gas vent, in the tubeworm field, and at the background site. The hydrology is variable with upward flow rates ranging from 1-90 cm/yr and downward flow rates from 3-130 cm/yr. Two distinct hydrologic pulsing events were sampled across the three mound sites, which advect a fluid from depth that further stabilizes the gas hydrate deposit. The hydrogeochemistry at Bush Hill seems to be influenced by multiple mechanisms such as active formation of gas hydrate, fluid influx and outflux due to active venting of CH4 at transient methane seeps at and near the mound, local salt tectonics, and density driven convection. The fluxes of fluid, solutes, and methane may have a significant impact on the seafloor biochemical environment and the water column chemistry at Bush Hill. (Author)

Gas-Dynamic Designing of the Exhaust System for the Air Brake

Science.gov (United States)

Novikova, Yu; Goriachkin, E.; Volkov, A.

2018-01-01

Each gas turbine engine is tested some times during the life-cycle. The test equipment includes the air brake that utilizes the power produced by the gas turbine engine. In actual conditions, the outlet pressure of the air brake does not change and is equal to atmospheric pressure. For this reason, for the air brake work it is necessary to design the special exhaust system. Mission of the exhaust system is to provide the required level of backpressure at the outlet of the air brake. The backpressure is required for the required power utilization by the air brake (the air brake operation in the required points on the performance curves). The paper is described the development of the gas dynamic canal, designing outlet guide vane and the creation of a unified exhaust system for the air brake. Using a unified exhaust system involves moving the operating point to the performance curve further away from the calculated point. However, the applying of one exhaust system instead of two will significantly reduce the cash and time costs.

Furnace draft dynamics analysis after a flue gas desulphurization system incorporation

Energy Technology Data Exchange (ETDEWEB)

Zazo, J.F.L. [Tecnatom, S.A. (Spain)

2007-07-01

Due to environmental regulations some utilities are modifying coal-fired power groups by installing a flue gas desulfurisation system (FGDS) in order to remove SO{sub 2} from a gas stream. These studies have been ordered by 'Endesa Generacion' for the following power plant groups: C.T. Teruel Grs. 1-3, C.T. Litoral Gr. 2, C.T. Compostilla Gr. 3, C.T. Alucdia Grs. 1-2, C.T. Compostilla Grs. 4-5 (on-going); and C.T. Los Barrios (on-going). The pictures that appear in this abstract correspond to Compostilla Gr.4 and Los Barrios projects. In both cases FGDS installation implies a new booster fan and heat exchanger keeping former Induced Draft Fans (IDFs). The main goal for these projects is to analyze the new flue-gas dynamic, in order to: detect risk situations to equipment, particularly to boiler integrity, test control system strategies and interlocks, select parameters to valves and control system to minimize pressure transients, and test operation strategies. 14 figs.

Integrated transport code system for a multicomponent plasma in a gas dynamic trap

International Nuclear Information System (INIS)

Anikeev, A.V.; Karpushov, A.N.; Noak, K.; Strogalova, S.L.

2000-01-01

This report is focused on the development of the theoretical and numerical models of multicomponent high-β plasma confinement and transport in the gas-dynamic trap (GDT). In order to simulate the plasma behavior in the GDT as well as that in the GDT-based neutron source the Integrated Transport Code System is developed from existing stand-alone codes calculating the target plasma, the fast ions and the neutral gas in the GDT. The code system considers the full dependence of the transport phenomena on space, time, energy and angle variables as well as the interactions between the particle fields [ru

Argon concentration time-series as a tool to study gas dynamics in the hyporheic zone.

Science.gov (United States)

Mächler, Lars; Brennwald, Matthias S; Kipfer, Rolf

2013-07-02

The oxygen dynamics in the hyporheic zone of a peri-alpine river (Thur, Switzerland), were studied through recording and analyzing the concentration time-series of dissolved argon, oxygen, carbon dioxide, and temperature during low flow conditions, for a period of one week. The argon concentration time-series was used to investigate the physical gas dynamics in the hyporheic zone. Differences in the transport behavior of heat and gas were determined by comparing the diel temperature evolution of groundwater to the measured concentration of dissolved argon. These differences were most likely caused by vertical heat transport which influenced the local groundwater temperature. The argon concentration time-series were also used to estimate travel times by cross correlating argon concentrations in the groundwater with argon concentrations in the river. The information gained from quantifying the physical gas transport was used to estimate the oxygen turnover in groundwater after water recharge. The resulting oxygen turnover showed strong diel variations, which correlated with the water temperature during groundwater recharge. Hence, the variation in the consumption rate was most likely caused by the temperature dependence of microbial activity.

Evaluation and reduction of respiratory motion artifacts in small animal SPECT with GATE

International Nuclear Information System (INIS)

Lee, C.-L.; Park, S.-J.; Kim, H.-J.

2015-01-01

The degradation of image quality caused by respiration is a major impediment to accurate lesion detection in single photon emission computed tomography (SPECT) imaging. This study was performed to evaluate the effects of lung motion on image quantification. A small animal SPECT system with NaI(Tl) was modeled in the Geant4 application for tomographic emission (GATE) simulation for a lung lesion using a 4D mouse whole-body phantom. SPECT images were obtained using 120 projection views acquired from 0 o to 360 o with a 3 o step. Slices were reconstructed using ordered subsets expectation maximization (OS-EM) without attenuation correction with five iterations and four subsets. Image quality was compared between the static mode without respiratory motion, and dynamic mode with respiratory motion in terms of spatial resolution was measured by the full width at half maximum (FWHM), signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR). The FWHM of the non-gated image and the respiratory gated image were also compared. Spatial resolution improved as activity increased and lesion diameter decreased in the static and dynamic modes. The SNR and CNR increased significantly as lesion activity increased and lesion diameter decreased. Our results show that respiratory motion leads to reduced contrast and quantitative accuracy and that image quantification depends on both the amplitude and the pattern of the respiratory motion. We verified that respiratory motion can have a major effect on the accuracy of measurement of lung lesions and that respiratory gating can reduce activity smearing on SPECT images

Dynamics of gas cell coalescence during baking expansion of leavened dough.

Science.gov (United States)

Miś, Antoni; Nawrocka, Agnieszka; Lamorski, Krzysztof; Dziki, Dariusz

2018-01-01

The investigation of the dynamics of gas cell coalescence, i.e. a phenomenon that deteriorates the homogeneity of the cellular structure of bread crumb, was carried out performing simultaneously measurements of the dough volume, pressure, and viscosity. It was demonstrated that, during the baking expansion of chemically leavened wheat flour dough, the maximum growth rate of the gas cell radius determined from the ratio of pressure exerted by the expanded dough to its viscosity was on average four-fold lower than that calculated from volume changes in the gas phase of the dough. Such a high discrepancy was interpreted as a result of the course of coalescence, and a formula for determination of its rate was developed. The coalescence rate in the initial baking expansion phase had negative values, indicating nucleation of newly formed gas cells, which increased the number of gas cells even by 8%. In the next baking expansion phase, the coalescence rate started to exhibit positive values, reflecting dominance of the coalescence phenomenon over nucleation. The maximum coalescence rates indicate that, during the period of the most intensive dough expansion, the number of gas cells decreased by 2-3% within one second. At the end of the formation of bread crumb, the number of the gas cells declined by 55-67% in comparison with the initial value. The correctness of the results was positively verified using X-ray micro-computed tomography. The developed method can be a useful tool for more profound exploration of the coalescence phenomenon at various stages of evolution of the cellular structure and its determinants, which may contribute to future development of more effective methods for improving the texture and sensory quality of bread crumb. Copyright © 2017 Elsevier Ltd. All rights reserved.

Molecular theory of mass transfer kinetics and dynamics at gas-water interface

International Nuclear Information System (INIS)

Morita, Akihiro; Garrett, Bruce C

2008-01-01

The mass transfer mechanism across gas-water interface is studied with molecular dynamics (MD) simulation. The MD results provide a robust and qualitatively consistent picture to previous studies about microscopic aspects of mass transfer, including interface structure, free energy profiles for the uptake, scattering dynamics and energy relaxation of impinging molecules. These MD results are quantitatively compared with experimental uptake measurements, and we find that the apparent inconsistency between MD and experiment could be partly resolved by precise decomposition of the observed kinetics into elemental steps. Remaining issues and future perspectives toward constructing a comprehensive multi-scale description of interfacial mass transfer are summarized.

Respiratory acidosis

Science.gov (United States)

Ventilatory failure; Respiratory failure; Acidosis - respiratory ... Causes of respiratory acidosis include: Diseases of the airways (such as asthma and COPD ) Diseases of the lung tissue (such as ...

Neuromuscular disease and respiratory physiology in children: putting lung function into perspective.

Science.gov (United States)

Fauroux, Brigitte; Khirani, Sonia

2014-08-01

Neuromuscular diseases represent a heterogeneous group of disorders of the muscle, nerve or neuromuscular junction. The respiratory muscles are rarely spared in neuromuscular diseases even if the type of muscle involvement, severity and time course greatly varies among the different diseases. Diagnosis of respiratory muscle weakness is crucial because of the importance of respiratory morbidity and mortality. Presently, routine respiratory evaluation is based on non-invasive volitional tests, such as the measurement of lung volumes, spirometry and the maximal static pressures, which may be difficult or impossible to obtain in some young children. Other tools or parameters are thus needed to assess the respiratory muscle weakness and its consequences in young children. The measurement of oesogastric pressures can be helpful as they allow the diagnosis and quantification of paradoxical breathing, as well as the assessment of the strength of the inspiratory and expiratory muscles by means of the oesophageal pressure during a maximal sniff and of the gastric pressure during a maximal cough. Sleep assessment should also be part of the respiratory evaluation of children with neuromuscular disease with at least the recording of nocturnal gas exchange if polysomnography is not possible or unavailable. This improvement in the assessment of respiratory muscle performance may increase our understanding of the respiratory pathophysiology of the different neuromuscular diseases, improve patient care, and guide research and innovative therapies by identifying and validating respiratory parameters. © 2014 Asian Pacific Society of Respirology.

Fundamental structural aspects and features in the bioengineering of the gas exchangers: comparative perspectives.

Science.gov (United States)

Maina, J N

2002-01-01

Over its life, an organism's survival and success are determined by the inventory of vital adaptations that its progenitors have creatively appropriated, devised and harnessed along the evolutionary pathway. Such conserved attributes provide the armamentarium necessary for withstanding the adverse effects of natural selection. Refinements of the designs of the respiratory organs have been critical for survival and phylogenetic advancement of animal life. Gas exchangers have changed in direct response to the respiratory needs of whole organisms in different environmental states and conditions. Nowhere else is the dictum that in biology 'there are no rules but only necessities' more manifest than in the evolutionary biology of the gas exchangers. The constructions have been continually fashioned and refined to meet specific needs. Solutions to common respiratory needs have been typified by profound structural convergence. Over the evolutionary continuum, as shifts in environmental situations occurred, infinitely many designs should theoretically have emerged. Moreover, without specific selective pressures and preference for certain designs, considering that there are only two naturally occurring respirable fluid media (air and water), air-lungs, water-lungs, air-gills and water-gills would have formed to similar extents. Factors such as body size, phylogenetic level of development, respiratory medium utilized and habitats occupied have permutatively prescribed the design of the gas exchangers. The construction of the modern gas exchangers has eventuated through painstaking cost-benefit analysis. Trade-offs and compromises have decreed only a limited number of structurally feasible and functionally competent outcomes. The morphological congruity (analogy) of the gas exchangers indicates that similar selective pressures have compelled the designs. Solutions to metabolic demands for molecular O2 have only differed in details. Passive physical diffusion, for example, is

Endotracheal Use of Perfluorane in Patients with Acute Respiratory Distress Syndrome Under Artificial Ventilation

Directory of Open Access Journals (Sweden)

V. V. Moroz

2005-01-01

Full Text Available The paper presents the results of a comparative study of different routes of intrapulmonary administration of perfluorane under artificial ventilation in patients with acute respiratory distress syndrome of various genesis. It shows the advantages and disadvantages of these routes, their impact on gas exchange, pulmonary biomechanical properties, cardiac hemodynamics, the transport and uptake of oxygen, the duration of respiratory support, and the length of stay in an intensive care unit.

Effect of differences in gas-dynamic behaviour on the separation performance of ultracentrifuges connected in parallel

International Nuclear Information System (INIS)

Portoghese, C.C.P.; Buchmann, J.H.

1996-01-01

This paper is concerned with the degradation of separation factors occurred when groups of ultracentrifuges having different gas-dynamic behaviour are connected in parallel arrangements. Differences in the gas-dynamic behavior were traduced in terms of different tails pressures for the same operational conditions, that are feed flow rate, product pressure and cut number. A mathematical model describing the ratio of the tails flow rates as a function of the tails pressure ratios and the feed flow rate was developed using experimental data collected from a pair of different ultracentrifuges connected in parallel. The optimization of model parameters was made using Marquardt's algorithm. The model developed was used to simulate the separation factors degradation in some parallel arrangements containing more than two centrifuges. Te obtained results were compared with experimental data collected from different groups of ultracentrifuges. It was observed that the calculated results were in good agreement with experimental data. This mathematical model, which parameters were determined in a two-centrifuges parallel arrangement, is useful to simulate the effect of quantified gas-dynamic differences in the separation factors of groups containing any number of different ultracentrifuges and, consequently, to analyze cascade losses due to this kind of occurrence. (author)

Respiratory impairment and the aging lung: a novel paradigm for assessing pulmonary function.

Science.gov (United States)

Vaz Fragoso, Carlos A; Gill, Thomas M

2012-03-01

Older persons have an increased risk of developing respiratory impairment because the aging lung is likely to have experienced exposures to environmental toxins as well as reductions in physiological capacity. Systematic review of risk factors and measures of pulmonary function that are most often considered when defining respiratory impairment in aging populations. Across the adult life span, there are frequent exposures to environmental toxins, including tobacco smoke, respiratory infections, air pollution, and occupational dusts. Concurrently, there are reductions in physiological capacity that may adversely affect ventilatory control, respiratory muscle strength, respiratory mechanics, and gas exchange. Recent work has provided a strong rationale for defining respiratory impairment as an age-adjusted reduction in spirometric measures of pulmonary function that are independently associated with adverse health outcomes. Specifically, establishing respiratory impairment based on spirometric Z-scores has been shown to be strongly associated with respiratory symptoms, frailty, and mortality. Alternatively, respiratory impairment may be defined by the peak expiratory flow, as measured by a peak flow meter. The peak expiratory flow, when expressed as a Z-score, has been shown to be strongly associated with disability and mortality. However, because it has a reduced diagnostic accuracy, peak expiratory flow should only define respiratory impairment when spirometry is not readily available or an older person cannot adequately perform spirometry. Aging is associated with an increased risk of developing respiratory impairment, which is best defined by spirometric Z-scores. Alternatively, in selected cases, respiratory impairment may be defined by peak expiratory flow, also expressed as a Z-score.

Obstructive sleep apnea in Down syndrome: Benefits of surgery and noninvasive respiratory support.

Science.gov (United States)

Dudoignon, Benjamin; Amaddeo, Alessandro; Frapin, Annick; Thierry, Briac; de Sanctis, Livio; Arroyo, Jorge Olmo; Khirani, Sonia; Fauroux, Brigitte

2017-08-01

Children with Down syndrome are at increased risk of obstructive sleep apnea (OSA). The aim of the study was to describe the management of OSA in a large cohort of children with Down syndrome. A retrospective analysis of sleep studies and consequent management was performed for all consecutive Down syndrome patients evaluated between September 2013 and April 2016. The data of 57 patients were analyzed: 51/53 had an interpretable overnight polygraphy and 4 the recording of nocturnal gas exchange. Mean age at baseline sleep study was 6.2 ± 5.9 years. Eighteen patients (32%) had prior upper airway surgery. Mean apnea-hypopnea index (AHI) was 14 ± 16 events/hr with 41 of the 51 (80%) patients having OSA with an AHI >1 event/hr and 20 patients (39%) having an AHI ≥10 events/hr. Consequently, eight patients (14%) had upper airway surgery. OSA improved in all patients except two who needed noninvasive respiratory support. Nineteen (33%) patients required noninvasive respiratory support. Mean age at noninvasive respiratory support initiation was 7 ± 7 years. On 11 patients with objective adherence data available, mean compliance at 2 ± 1 years of treatment was excellent with an average use per night of 8 hr46 ± 3 hr59 and 9 patients using the noninvasive respiratory support >4 hr/night. Noninvasive respiratory support was associated with an improvement of nocturnal gas exchange. The prevalence of OSA is high in Down syndrome. Upper airway surgery is not always able to correct OSA. Noninvasive respiratory support represents then an effective treatment for OSA and good compliance may be achieved in a majority of patients. © 2017 Wiley Periodicals, Inc.

Hydrodynamic performance of a single-use aerated stirred bioreactor in animal cell culture: applications of tomography, dynamic gas disengagement (DGD), and CFD.

Science.gov (United States)

Kazemzadeh, Argang; Elias, Cynthia; Tamer, Melih; Ein-Mozaffari, Farhad

2018-05-01

The hydrodynamics of gas-liquid two-phase flow in a single-use bioreactor were investigated in detail both experimentally and numerically. Electrical resistance tomography (ERT) and dynamic gas disengagement (DGD) combined with computational fluid dynamics (CFD) were employed to assess the effect of the volumetric gas flow rate and impeller speed on the gas-liquid flow field, local and global gas holdup values, and Sauter mean bubble diameter. From the results obtained from DGD coupled with ERT, the bubble sizes were determined. The experimental data indicated that the total gas holdup values increased with increasing both the rotational speed of impeller and volumetric gas flow rate. Moreover, the analysis of the flow field generated inside the aerated stirred bioreactor was conducted using CFD results. Overall, a more uniform distribution of the gas holdup was obtained at impeller speeds ≥ 100 rpm for volumetric gas flow rates ≥ 1.6 × 10 -5  m 3 /s.

Shock structure in continuum models of gas dynamics: stability and bifurcation analysis

International Nuclear Information System (INIS)

Simić, Srboljub S

2009-01-01

The problem of shock structure in gas dynamics is analysed through a comparative study of two continuum models: the parabolic Navier–Stokes–Fourier model and the hyperbolic system of 13 moments equations modeling viscous, heat-conducting monatomic gases within the context of extended thermodynamics. When dissipative phenomena are neglected these models both reduce to classical Euler's equations of gas dynamics. The shock profile solution, assumed in the form of a planar travelling wave, reduces the problem to a system of ordinary differential equations, and equilibrium states appear to be stationary points of the system. It is shown that in both models an upstream equilibrium state suffers an exchange of stability when the shock speed crosses the critical value which coincides with the highest characteristic speed of the Euler's system. At the same time a downstream equilibrium state could be seen as a steady bifurcating solution, while the shock profile represents a heteroclinic orbit connecting the two stationary points. Using centre manifold reduction it is demonstrated that both models, although mathematically different, obey the same transcritical bifurcation pattern in the neighbourhood of the bifurcation point corresponding to the critical value of shock speed, the speed of sound

Real-time system for respiratory-cardiac gating in positron tomography

International Nuclear Information System (INIS)

Klein, G.J.; Reutter, B.W.; Ho, M.H.; Huesman, R.H.; Reed, J.H.

1998-01-01

A Macintosh-based signal processing system has been developed to support simultaneous respiratory and cardiac gating on the ECAT EXACT HR PET scanner. Using the Lab-View real-time software environment, the system reads analog inputs from a pneumatic respiratory bellows and an EGG monitor to compute an appropriate histogram memory location for the PET data. Respiratory state is determined by the bellows signal amplitude; cardiac state is based on the time since the last R-wave. These two states are used in a 2D lookup table to determine a combined respiratory-cardiac state. A 4-bit address encoding the selected histogram is directed from the system to the ECAT scanner, which dynamically switches the destination of tomograph events as respiratory-cardiac state changes. to Test the switching efficiency of the combined Macintosh/ECAT system, a rotating emission phantom was built. Acquisitions with 25 msec states while the phantom was rotating at 240 rpm demonstrate the system could effectively stop motion at this rate, with approximately 5 msec switching time between states

Gas-surface interactions using accommodation coefficients for a dilute and a dense gas in a micro/nano-channel : heat flux predictions using combined molecular dynamics and Monte Carlo techniques

NARCIS (Netherlands)

Gaastra - Nedea, S.V.; Steenhoven, van A.A.; Markvoort, A.J.; Spijker, P.; Giordano, D.

2014-01-01

The influence of gas-surface interactions of a dilute gas confined between two parallel walls on the heat flux predictions is investigated using a combined Monte Carlo (MC) and molecular dynamics (MD) approach. The accommodation coefficients are computed from the temperature of incident and

The Mexican energy sector: integrated dynamic analysis of the natural gas/refining system

International Nuclear Information System (INIS)

Barnes-Regueiro, Francisco; Leach, Matthew; Ruth, Matthias

2002-01-01

Environmental regulations in Mexico could dramatically increase demand for natural gas in the following years. This increase could lead to gas price shocks and a counter-intuitive increase in carbon emissions. The effect would be accentuated if Mexico lacks the funds required to carry on with investments in gas development and processing capacity. With the use of a dynamic computer model, this study addresses responses of the Mexican oil and gas industries to perturbations such as: changes in regulatory and environmental policies; changes in institutional arrangements such as those arising from market liberalization; and lack of availability of investment funds. The study also assesses how regulatory policies can be designed to minimize the economic inefficiencies arising from the business cycle disruptions that some perturbations may cause. In addition, this study investigates how investment responses will shape the Mexican energy sector in the future, particularly with respect to both the relative importance of different fuels for power generation and heating purposes and the nature of competition in the Mexican natural gas market. Furthermore, this study explores the direct consequences of these responses on the level of carbon emissions. (Author)

Correlation between arterial blood gas analysis and peripheral blood gas analysis in acid-base unbalance state

Directory of Open Access Journals (Sweden)

Hyun Lee Kim

2012-06-01

Full Text Available Acid-base unbalance is most common problem in severe ill patient, especially in condition of abnormal renal function state. Acid-base unbalances are respiratory acidosis, respiratory alkalosis, metabolic acidosis, and metabolic alkalosis. Metabolic acidosis is frequently appeared in clinical state. Arterial blood gas analysis is considered as a basic test to the intensive care unit patient and emergency state. Recently some researches were done, comparing with arterial blood gas analysis and venous blood gas analysis. Because of venous blood sampling is safer than arterial blood gas analysis, and beside not so different among them for detecting pH, pCO2, HCO3, except pO2 measuring. This research was done in emergency room, and for explaining no different between arterial blood gas analysis and peripheral blood gas analysis result in acid-base unbalance state patient. Especially in kidney functions decreased state. : The study was done from March, 2010 to January, 2011. The object was 89 peoples who came to emergency room for treating internal medicine problem. (Women 53, average age: 66.7±12.1 Then compare between arterial blood gas analysis and peripheral blood gas analysis. Result: The mean arterial minus venous difference for pH, pCO2, and bicarbonate was −0.0170, 2.6528, and 0.6124. Bland-Altman plot was done for predicting agreement of two groups, and the scale was pH −2.95 to 4.17, pCO2 −4.45 to 9.76, bicarbonate −2.95 to 4.16, in 95% relative. Conclusion: The peripheral blood gas pH, pCO2, bicarbonate level is almost same as arterial blood gas analysis results. And enough to measuring acid-base unbalance state, in absent of arterial blood testing.

New Iterative Method for Fractional Gas Dynamics and Coupled Burger’s Equations

Directory of Open Access Journals (Sweden)

Mohamed S. Al-luhaibi

2015-01-01

Full Text Available This paper presents the approximate analytical solutions to solve the nonlinear gas dynamics and coupled Burger’s equations with fractional time derivative. By using initial values, the explicit solutions of the equations are solved by using a reliable algorithm. Numerical results show that the new iterative method is easy to implement and accurate when applied to time-fractional partial differential equations.

Simple gas chromatographic system for analysis of microbial respiratory gases

Science.gov (United States)

Carle, G. C.

1972-01-01

Dual column ambient temperature system, consisting of pair of capillary columns, microbead thermistor detector and micro gas-sampling valve, is used in remote life-detection equipment for space experiments. Performance outweighs advantage gained by utilizing single-column systems to reduce weight, conserve carrier gas and operate at lower power levels.

Vorticity and symplecticity in multi-symplectic, Lagrangian gas dynamics

Science.gov (United States)

Webb, G. M.; Anco, S. C.

2016-02-01

The Lagrangian, multi-dimensional, ideal, compressible gas dynamic equations are written in a multi-symplectic form, in which the Lagrangian fluid labels, m i (the Lagrangian mass coordinates) and time t are the independent variables, and in which the Eulerian position of the fluid element {x}={x}({m},t) and the entropy S=S({m},t) are the dependent variables. Constraints in the variational principle are incorporated by means of Lagrange multipliers. The constraints are: the entropy advection equation S t = 0, the Lagrangian map equation {{x}}t={u} where {u} is the fluid velocity, and the mass continuity equation which has the form J=τ where J={det}({x}{ij}) is the Jacobian of the Lagrangian map in which {x}{ij}=\\partial {x}i/\\partial {m}j and τ =1/ρ is the specific volume of the gas. The internal energy per unit volume of the gas \\varepsilon =\\varepsilon (ρ ,S) corresponds to a non-barotropic gas. The Lagrangian is used to define multi-momenta, and to develop de Donder-Weyl Hamiltonian equations. The de Donder-Weyl equations are cast in a multi-symplectic form. The pullback conservation laws and the symplecticity conservation laws are obtained. One class of symplecticity conservation laws give rise to vorticity and potential vorticity type conservation laws, and another class of symplecticity laws are related to derivatives of the Lagrangian energy conservation law with respect to the Lagrangian mass coordinates m i . We show that the vorticity-symplecticity laws can be derived by a Lie dragging method, and also by using Noether’s second theorem and a fluid relabelling symmetry which is a divergence symmetry of the action. We obtain the Cartan-Poincaré form describing the equations and we discuss a set of differential forms representing the equation system.

Dynamical analysis of an n‑H‑T cosmological quintessence real gas model with a general equation of state

Science.gov (United States)

Ivanov, Rossen I.; Prodanov, Emil M.

2018-01-01

The cosmological dynamics of a quintessence model based on real gas with general equation of state is presented within the framework of a three-dimensional dynamical system describing the time evolution of the number density, the Hubble parameter and the temperature. Two global first integrals are found and examples for gas with virial expansion and van der Waals gas are presented. The van der Waals system is completely integrable. In addition to the unbounded trajectories, stemming from the presence of the conserved quantities, stable periodic solutions (closed orbits) also exist under certain conditions and these represent models of a cyclic Universe. The cyclic solutions exhibit regions characterized by inflation and deflation, while the open trajectories are characterized by inflation in a “fly-by” near an unstable critical point.

Differential oxygen dynamics in two diverse Dunning prostate R3327 rat tumor sublines (MAT-Lu and HI) with respect to growth and respiratory challenge

International Nuclear Information System (INIS)

Zhao Dawen; Constantinescu, Anca; Hahn, Eric W.; Mason, Ralph P.

2002-01-01

Purpose: Since hypoxia may influence tumor response to therapy and prognosis, we have compared oxygenation of tumors known to exhibit differential growth rate and tissue differentiation. Methods and Materials: Regional tumor oxygen tension was measured using 19 F nuclear magnetic resonance echo planar imaging relaxometry of hexafluorobenzene, which provided dynamic maps with respect to respiratory intervention. Investigations used two Dunning prostate R3327 rat tumor sublines: the fast growing, highly metastatic MAT-Lu and the moderately well-differentiated, slower growing HI. Results: Both sublines showed significantly higher oxygen tension in smaller tumors ( 3 ) than in larger tumors (>3.5 cm 3 ). Pooled data showed that MAT-Lu tumors exhibited greater hypoxia compared with the size-matched HI tumors (p 2 for tumors of both sublines (p 2 , while those in the MAT-Lu tumors showed little response to respiratory intervention. Conclusions: These results concur with hypotheses that hypoxia is related to tumor growth rate and degree of differentiation. Under baseline conditions, the differences were subtle. However, response to respiratory intervention revealed highly significant differences, which, if held valid in the clinic, could have prognostic value

Respiratory alkalosis

Science.gov (United States)

Alkalosis - respiratory ... leads to shortness of breath can also cause respiratory alkalosis (such as pulmonary embolism and asthma). ... Treatment is aimed at the condition that causes respiratory alkalosis. Breathing into a paper bag -- or using ...

Incremental exercise test performance with and without a respiratory ...

African Journals Online (AJOL)

2008-11-08

Nov 8, 2008 ... Pulmonary gas exchange and ventilation were analysed with ... dioxide production (VCO2), minute ventilation (VE), respiratory rate. (fR) and .... Protective masks typically have a dead space of 150 - 500 ml and flow resistance of 8.0. - 10.0 cm H2O∙l-1∙s-1 compared with 70 - 150 ml dead space and 0.6 -.

Molecular dynamics simulations of classical sound absorption in a monatomic gas

Science.gov (United States)

Ayub, M.; Zander, A. C.; Huang, D. M.; Cazzolato, B. S.; Howard, C. Q.

2018-05-01

Sound wave propagation in argon gas is simulated using molecular dynamics (MD) in order to determine the attenuation of acoustic energy due to classical (viscous and thermal) losses at high frequencies. In addition, a method is described to estimate attenuation of acoustic energy using the thermodynamic concept of exergy. The results are compared against standing wave theory and the predictions of the theory of continuum mechanics. Acoustic energy losses are studied by evaluating various attenuation parameters and by comparing the changes in behavior at three different frequencies. This study demonstrates acoustic absorption effects in a gas simulated in a thermostatted molecular simulation and quantifies the classical losses in terms of the sound attenuation constant. The approach can be extended to further understanding of acoustic loss mechanisms in the presence of nanoscale porous materials in the simulation domain.

Thermal fluid dynamic behavior of coolant helium gas in a typical reactor VHTGR channel of prismatic core

International Nuclear Information System (INIS)

Belo, Allan Cavalcante

2016-01-01

The current studies about the thermal fluid dynamic behavior of the VHTGR core reactors of 4 th generation are commonly developed in 3-D analysis in CFD (computational fluid dynamics), which often requires considerable time and complex mathematical calculations for carrying out these analysis. The purpose of this project is to achieve thermal fluid dynamic analysis of flow of gas helium refrigerant in a typical channel of VHTGR prismatic core reactor evaluating magnitudes of interest such as temperature, pressure and fluid velocity and temperature distribution in the wall of the coolant channel from the development of a computer code in MATLAB considering the flow on one-dimensional channel, thereby significantly reducing the processing time of calculations. The model uses three different references to the physical properties of helium: expressions given by the KTA (German committee of nuclear safety standards), the computational tool REFPROP and a set of constant values for the entire channel. With the use of these three references it is possible to simulate the flow treating the gas both compressible and incompressible. The results showed very close values for the interest quantities and revealed that there are no significant differences in the use of different references used in the project. Another important conclusion to be observed is the independence of helium in the gas compressibility effects on thermal fluid dynamic behavior. The study also indicated that the gas undergoes no severe effects due to high temperature variations in the channel, since this goes in the channel at 914 K and exits at approximately 1263 K, which shows the excellent use of helium as a refrigerant fluid in reactor channels VHTGR. The comparison of results obtained in this work with others in the literature served to confirm the effectiveness of the one-dimensional consideration of method of gas flow in the coolant channel to replace the models made in 3-D for the pressure range and

Dynamic performance of a combined gas turbine and air bottoming cycle plant for off-shore applications

DEFF Research Database (Denmark)

Benato, Alberto; Pierobon, Leonardo; Haglind, Fredrik

2014-01-01

and a combined gas turbine coupled with an air bottoming cycle plant. The case study is the Draugen off-shore oil and gas platform, located in the North Sea, Norway. The normal electricity demand is 19 MW, currently covered by two gas turbines generating each 50% of the power demand, while the third turbine......When the Norwegian government introduced the CO2 tax for hydrocarbon fuels, the challenge became to improve the performance of off-shore power systems. An oil and gas platform typically operates on an island (stand-alone system) and the power demand is covered by two or more gas turbines. In order...... to improve the plant performance, a bottoming cycle unit can be added to the gas turbine topping module, thus constituting a combined cycle plant. This paper aims at developing and testing the numerical model simulating the part-load and dynamic behavior of a novel power system, composed of two gas turbines...

Gas Price Formation, Structure and Dynamics

Energy Technology Data Exchange (ETDEWEB)

Davoust, R.

2008-07-01

Our study, focused on gas prices in importing economies, describes wholesale prices and retail prices, their evolution for the last one or two decades, the economic mechanisms of price formation. While an international market for oil has developed thanks to moderate storage and transportation charges, these costs are much higher in the case of natural gas, which involves that this energy is still traded inside continental markets. There are three regional gas markets around the world: North America (the United States, importing mainly from Canada and Mexico), Europe (importing mainly from Russia, Algeria and Norway) and Asia (Japan, Korea, Taiwan, China and India, importing mainly from Indonesia, Malaysia and Australia). A market for gas has also developed in South America, but it will not be covered by our paper. In Europe and the US, due to large domestic resources and strong grids, natural gas is purchased mostly through pipelines. In Northeast Asia, there is a lack of such infrastructures, so imported gas takes mainly the form of Liquefied Natural Gas (LNG), shipped on maritime tankers. Currently, the LNG market is divided into two zones: the Atlantic Basin (Europe and US) and the Pacific Basin (Asia and the Western Coast of America). For the past few years, the Middle East and Africa have tended to be crucial suppliers for both LNG zones. Gas price formation varies deeply between regional markets, depending on several structural factors (regulation, contracting practises, existence of a spot market, liquidity, share of imports). Empirically, the degree of market opening (which corresponds to the seniority in the liberalization process) seems to be the primary determinant of pricing patterns. North America has the most liberalized and well-performing natural gas industry in the world. Gas pricing is highly competitive and is based on supply/demand balances. Spot and futures markets are developed. The British gas sector is also deregulated and thus follows a

Gas Price Formation, Structure and Dynamics

International Nuclear Information System (INIS)

Davoust, R.

2008-01-01

Our study, focused on gas prices in importing economies, describes wholesale prices and retail prices, their evolution for the last one or two decades, the economic mechanisms of price formation. While an international market for oil has developed thanks to moderate storage and transportation charges, these costs are much higher in the case of natural gas, which involves that this energy is still traded inside continental markets. There are three regional gas markets around the world: North America (the United States, importing mainly from Canada and Mexico), Europe (importing mainly from Russia, Algeria and Norway) and Asia (Japan, Korea, Taiwan, China and India, importing mainly from Indonesia, Malaysia and Australia). A market for gas has also developed in South America, but it will not be covered by our paper. In Europe and the US, due to large domestic resources and strong grids, natural gas is purchased mostly through pipelines. In Northeast Asia, there is a lack of such infrastructures, so imported gas takes mainly the form of Liquefied Natural Gas (LNG), shipped on maritime tankers. Currently, the LNG market is divided into two zones: the Atlantic Basin (Europe and US) and the Pacific Basin (Asia and the Western Coast of America). For the past few years, the Middle East and Africa have tended to be crucial suppliers for both LNG zones. Gas price formation varies deeply between regional markets, depending on several structural factors (regulation, contracting practises, existence of a spot market, liquidity, share of imports). Empirically, the degree of market opening (which corresponds to the seniority in the liberalization process) seems to be the primary determinant of pricing patterns. North America has the most liberalized and well-performing natural gas industry in the world. Gas pricing is highly competitive and is based on supply/demand balances. Spot and futures markets are developed. The British gas sector is also deregulated and thus follows a

Evaluation of an optoacoustic based gas analysing device

Science.gov (United States)

Markmann, Janine; Lange, Birgit; Theisen-Kunde, Dirk; Danicke, Veit; Mayorov, Fedor; Eckert, Sebastian; Kettmann, Pascal; Brinkmann, Ralf

2017-07-01

The relative occurrence of volatile organic compounds in the human respiratory gas is disease-specific (ppb range). A prototype of a gas analysing device using two tuneable laser systems, an OPO-laser (2.5 to 10 μm) and a CO2-laser (9 to 11 μm), and an optoacoustic measurement cell was developed to detect concentrations in the ppb range. The sensitivity and resolution of the system was determined by test gas measurements, measuring ethylene and sulfur hexafluoride with the CO2-laser and butane with the OPO-laser. System sensitivity found to be 13 ppb for sulfur hexafluoride, 17 ppb for ethylene and Respiratory gas samples of 8 healthy volunteers were investigated by irradiation with 17 laser lines of the CO2-laser. Several of those lines overlap with strong absorption bands of ammonia. As it is known that ammonia concentration increases by age a separation of people 35 was striven for. To evaluate the data the first seven gas samples were used to train a discriminant analysis algorithm. The eighth subject was then assigned correctly to the group >35 years with the age of 49 years.

Dynamic structure factor of the normal Fermi gas from the collisionless to the hydrodynamic regime

International Nuclear Information System (INIS)

Watabe, Shohei; Nikuni, Tetsuro

2010-01-01

The dynamic structure factor of a normal Fermi gas is investigated by using the moment method for the Boltzmann equation. We determine the spectral function at finite temperatures over the full range of crossover from the collisionless regime to the hydrodynamic regime. We find that the Brillouin peak in the dynamic structure factor exhibits a smooth crossover from zero to first sound as functions of temperature and interaction strength. The dynamic structure factor obtained using the moment method also exhibits a definite Rayleigh peak (ω∼0), which is a characteristic of the hydrodynamic regime. We compare the dynamic structure factor obtained by the moment method with that obtained from the hydrodynamic equations.

Constant flow ventilation as a novel approach to elimination of respiratory artifact in MR imaging

International Nuclear Information System (INIS)

Shtern, F.; Kersh, R.; Lee, A.; Venegas, J.; Brady, T.J.

1988-01-01

This pilot study was performed to evaluate constant flow ventilation (CFV) as a method of respiratory artifact suppression in magnetic resonance (MR) imaging. In contrast to currently used methods of respiratory artifact suppression, CFV is able to provide adequate ventilation in the absence of any chest wall motion and thus obviates the need for respiratory gating. High-velocity jets of fresh gas delivered through two narrow (2-mm) intrabronchial cannulas promote gas exchange through airway turbulence and enhanced molecular diffusion. One mongrel dog (8.5 kg) was anesthetized with pentobarbital (35 mg/kg). For CFV, endobronchial cannulas were inserted with the aid of bronchoscopy and connected to a flow meter (flow rate, 500 mL/sec). Intrathoracic pressure was monitored via a pressure transducer connected to an air-filled intraesophageal balloon. Conventional ventilation (CV), with a tidal volume of 85 mL and ten breaths per minute, was provided through a cuffed endotracheal tube. After establishment of adequate ventilation (carbon dioxide pressure, 39), muscle paralysis was induced by succinylcholine at 0.1 mg/kg. T2-weighted [1,500/50 (repetition time msec/echo time msec), two excitations] gradient-echo and spin-echo images were obtained at 0.6T with both CV and CFV. MR images with CFV were free of respiratory motion artifact, which was present on all MR images with CV. This pilot study indicates that implementation of CFV results in elimination of respiratory motion artifact

Gas-particle interactions in dense gas-fluidised beds

NARCIS (Netherlands)

Li, J.; Kuipers, J.A.M.

2003-01-01

The occurrence of heterogeneous flow structures in gas-particle flows seriously affects gas¿solid contacting and transport processes in dense gas-fluidized beds. A computational study, using a discrete particle method based on Molecular Dynamics techniques, has been carried out to explore the

Fluctuations in non-ideal pion gas with dynamically fixed particle number

Science.gov (United States)

Kolomeitsev, E. E.; Voskresensky, D. N.

2018-05-01

We consider a non-ideal hot pion gas with the dynamically fixed number of particles in the model with the λϕ4 interaction. The effective Lagrangian for the description of such a system is obtained after dropping the terms responsible for the change of the total particle number. Reactions π+π- ↔π0π0, which determine the isospin balance of the medium, are permitted. Within the self-consistent Hartree approximation we compute the effective pion mass, thermodynamic characteristics of the system and the variance of the particle number at temperatures above the critical point of the induced Bose-Einstein condensation when the pion chemical potential reaches the value of the effective pion mass. We analyze conditions for the condensate formation in the process of thermalization of an initially non-equilibrium pion gas. The normalized variance of the particle number increases with a temperature decrease but remains finite in the critical point of the Bose-Einstein condensation. This is due to the non-perturbative account of the interaction and is in contrast to the ideal-gas case. In the kinetic regime of the condensate formation the variance is shown to stay finite also.

Instantaneous Respiratory Estimation from Thoracic Impedance by Empirical Mode Decomposition.

Science.gov (United States)

Wang, Fu-Tai; Chan, Hsiao-Lung; Wang, Chun-Li; Jian, Hung-Ming; Lin, Sheng-Hsiung

2015-07-07

Impedance plethysmography provides a way to measure respiratory activity by sensing the change of thoracic impedance caused by inspiration and expiration. This measurement imposes little pressure on the body and uses the human body as the sensor, thereby reducing the need for adjustments as body position changes and making it suitable for long-term or ambulatory monitoring. The empirical mode decomposition (EMD) can decompose a signal into several intrinsic mode functions (IMFs) that disclose nonstationary components as well as stationary components and, similarly, capture respiratory episodes from thoracic impedance. However, upper-body movements usually produce motion artifacts that are not easily removed by digital filtering. Moreover, large motion artifacts disable the EMD to decompose respiratory components. In this paper, motion artifacts are detected and replaced by the data mirrored from the prior and the posterior before EMD processing. A novel intrinsic respiratory reconstruction index that considers both global and local properties of IMFs is proposed to define respiration-related IMFs for respiration reconstruction and instantaneous respiratory estimation. Based on the experiments performing a series of static and dynamic physical activates, our results showed the proposed method had higher cross correlations between respiratory frequencies estimated from thoracic impedance and those from oronasal airflow based on small window size compared to the Fourier transform-based method.

Life-threatening hypokalemia following rapid correction of respiratory acidosis.

Science.gov (United States)

Hammond, Kendra; You, David; Collins, Eileen G; Leehey, David J; Laghi, Franco

2013-01-01

A 56-year-old woman with a history of paraplegia and chronic pain due to neuromyelitis optica (Devic's syndrome) was admitted to a spinal cord injury unit for management of a sacral decubitus ulcer. During the hospitalization, she required emergency transfer to the intensive care unit (ICU) because of progressive deterioration of respiratory muscle function, severe respiratory acidosis, obtundation and hypotension. Upon transfer to the ICU, arterial blood gas revealed severe acute-on-chronic respiratory acidosis (pH 7.00, PCO2 120 mm Hg, PO2 211 mm Hg). The patient was immediately intubated and mechanically ventilated. Intravenous fluid boluses of normal saline (10.5 L in about 24 h) and vasopressors were started with rapid correction of hypotension. In addition, she was given hydrocortisone. Within 40 min of initiation of mechanical ventilation, there was improvement in acute respiratory acidosis. Sixteen hours later, however, the patient developed life-threatening hypokalemia (K(+) of 2.1 mEq/L) and hypomagnesemia (Mg of 1.4 mg/dL). Despite aggressive potassium supplementation, hypokalemia continued to worsen over the next several hours (K(+) of 1.7 mEq/L). Urine studies revealed renal potassium wasting. We reason that the recalcitrant life-threatening hypokalemia was caused by several mechanisms including total body potassium depletion (chronic respiratory acidosis), a shift of potassium from the extracellular to intracellular space (rapid correction of respiratory acidosis with mechanical ventilation), increased sodium delivery to the distal nephron (normal saline resuscitation), hyperaldosteronism (secondary to hypotension plus administration of hydrocortisone) and hypomagnesemia. We conclude that rapid correction of respiratory acidosis, especially in the setting of hypotension, can lead to life-threatening hypokalemia. Serum potassium levels must be monitored closely in these patients, as failure to do so can lead to potentially lethal consequences

Slow quench dynamics of a one-dimensional Bose gas confined to an optical lattice.

Science.gov (United States)

Bernier, Jean-Sébastien; Roux, Guillaume; Kollath, Corinna

2011-05-20

We analyze the effect of a linear time variation of the interaction strength on a trapped one-dimensional Bose gas confined to an optical lattice. The evolution of different observables such as the experimentally accessible on site particle distribution are studied as a function of the ramp time by using time-dependent numerical techniques. We find that the dynamics of a trapped system typically displays two regimes: For long ramp times, the dynamics is governed by density redistribution, while at short ramp times, local dynamics dominates as the evolution is identical to that of an homogeneous system. In the homogeneous limit, we also discuss the nontrivial scaling of the energy absorbed with the ramp time.

A paradigm for modeling and computation of gas dynamics

Science.gov (United States)

Xu, Kun; Liu, Chang

2017-02-01

In the continuum flow regime, the Navier-Stokes (NS) equations are usually used for the description of gas dynamics. On the other hand, the Boltzmann equation is applied for the rarefied flow. These two equations are based on distinguishable modeling scales for flow physics. Fortunately, due to the scale separation, i.e., the hydrodynamic and kinetic ones, both the Navier-Stokes equations and the Boltzmann equation are applicable in their respective domains. However, in real science and engineering applications, they may not have such a distinctive scale separation. For example, around a hypersonic flying vehicle, the flow physics at different regions may correspond to different regimes, where the local Knudsen number can be changed significantly in several orders of magnitude. With a variation of flow physics, theoretically a continuous governing equation from the kinetic Boltzmann modeling to the hydrodynamic Navier-Stokes dynamics should be used for its efficient description. However, due to the difficulties of a direct modeling of flow physics in the scale between the kinetic and hydrodynamic ones, there is basically no reliable theory or valid governing equations to cover the whole transition regime, except resolving flow physics always down to the mean free path scale, such as the direct Boltzmann solver and the Direct Simulation Monte Carlo (DSMC) method. In fact, it is an unresolved problem about the exact scale for the validity of the NS equations, especially in the small Reynolds number cases. The computational fluid dynamics (CFD) is usually based on the numerical solution of partial differential equations (PDEs), and it targets on the recovering of the exact solution of the PDEs as mesh size and time step converging to zero. This methodology can be hardly applied to solve the multiple scale problem efficiently because there is no such a complete PDE for flow physics through a continuous variation of scales. For the non-equilibrium flow study, the direct

Imaging and dosimetric errors in 4D PET/CT-guided radiotherapy from patient-specific respiratory patterns: a dynamic motion phantom end-to-end study.

Science.gov (United States)

Bowen, S R; Nyflot, M J; Herrmann, C; Groh, C M; Meyer, J; Wollenweber, S D; Stearns, C W; Kinahan, P E; Sandison, G A

2015-05-07

of errors was comparable during PET/CT imaging and treatment delivery without motion compensation. Errors were moderately mitigated during PET/CT imaging and significantly mitigated during RT delivery with motion compensation. This dynamic motion phantom end-to-end workflow provides a method for quality assurance of 4D PET/CT-guided radiotherapy, including evaluation of respiratory motion compensation methods during imaging and treatment delivery.

Imaging and dosimetric errors in 4D PET/CT-guided radiotherapy from patient-specific respiratory patterns: a dynamic motion phantom end-to-end study

International Nuclear Information System (INIS)

Bowen, S R; Nyflot, M J; Meyer, J; Sandison, G A; Herrmann, C; Groh, C M; Wollenweber, S D; Stearns, C W; Kinahan, P E

2015-01-01

planning, and RT delivery under a dose painting paradigm is feasible within an integrated respiratory motion phantom workflow. For a limited set of cases, the magnitude of errors was comparable during PET/CT imaging and treatment delivery without motion compensation. Errors were moderately mitigated during PET/CT imaging and significantly mitigated during RT delivery with motion compensation. This dynamic motion phantom end-to-end workflow provides a method for quality assurance of 4D PET/CT-guided radiotherapy, including evaluation of respiratory motion compensation methods during imaging and treatment delivery. (paper)

Alfalfa discovery of the nearby gas-rich dwarf galaxy LEO P. V. Neutral gas dynamics and kinematics

International Nuclear Information System (INIS)

Bernstein-Cooper, Elijah Z.; Pardy, Stephen A.; Cannon, John M.

2014-01-01

We present new H I spectral line imaging of the extremely metal-poor, star-forming dwarf irregular galaxy Leo P. Our H I images probe the global neutral gas properties and the local conditions of the interstellar medium (ISM). The H I morphology is slightly elongated along the optical major axis. We do not find obvious signatures of interaction or infalling gas at large spatial scales. The neutral gas disk shows obvious rotation, although the velocity dispersion is comparable to the rotation velocity. The rotation amplitude is estimated to be V c =15 ± 5 km s –1 . Within the H I radius probed by these observations, the mass ratio of gas to stars is roughly 2:1, while the ratio of the total mass to the baryonic mass is ≳15:1. We use this information to place Leo P on the baryonic Tully-Fisher relation, testing the baryonic content of cosmic structures in a sparsely populated portion of parameter space that has hitherto been occupied primarily by dwarf spheroidal galaxies. We detect the signature of two temperature components in the neutral ISM of Leo P; the cold and warm components have characteristic velocity widths of 4.2 ± 0.9 km s –1 and 10.1 ± 1.2 km s –1 , corresponding to kinetic temperature upper limits of ∼1100 K and ∼6200 K, respectively. The cold H I component is unresolved at a physical resolution of 200 pc. The highest H I surface densities are observed in close physical proximity to the single H II region. A comparison of the neutral gas properties of Leo P with other extremely metal-deficient (XMD) galaxies reveals that Leo P has the lowest neutral gas mass of any known XMD, and that the dynamical mass of Leo P is more than two orders of magnitude smaller than any known XMD with comparable metallicity.

Alfalfa discovery of the nearby gas-rich dwarf galaxy LEO P. V. Neutral gas dynamics and kinematics

Energy Technology Data Exchange (ETDEWEB)

Bernstein-Cooper, Elijah Z.; Pardy, Stephen A. [Department of Astronomy, University of Wisconsin, 475 N Charter Street, Madison, WI 53706 (United States); Cannon, John M., E-mail: ezbc@astro.wisc.edu, E-mail: spardy@astro.wisc.edu, E-mail: jcannon@macalester.edu [Department of Physics and Astronomy, Macalester College, 1600 Grand Avenue, Saint Paul, MN 55105 (United States); and others

2014-08-01

We present new H I spectral line imaging of the extremely metal-poor, star-forming dwarf irregular galaxy Leo P. Our H I images probe the global neutral gas properties and the local conditions of the interstellar medium (ISM). The H I morphology is slightly elongated along the optical major axis. We do not find obvious signatures of interaction or infalling gas at large spatial scales. The neutral gas disk shows obvious rotation, although the velocity dispersion is comparable to the rotation velocity. The rotation amplitude is estimated to be V {sub c} =15 ± 5 km s{sup –1}. Within the H I radius probed by these observations, the mass ratio of gas to stars is roughly 2:1, while the ratio of the total mass to the baryonic mass is ≳15:1. We use this information to place Leo P on the baryonic Tully-Fisher relation, testing the baryonic content of cosmic structures in a sparsely populated portion of parameter space that has hitherto been occupied primarily by dwarf spheroidal galaxies. We detect the signature of two temperature components in the neutral ISM of Leo P; the cold and warm components have characteristic velocity widths of 4.2 ± 0.9 km s{sup –1} and 10.1 ± 1.2 km s{sup –1}, corresponding to kinetic temperature upper limits of ∼1100 K and ∼6200 K, respectively. The cold H I component is unresolved at a physical resolution of 200 pc. The highest H I surface densities are observed in close physical proximity to the single H II region. A comparison of the neutral gas properties of Leo P with other extremely metal-deficient (XMD) galaxies reveals that Leo P has the lowest neutral gas mass of any known XMD, and that the dynamical mass of Leo P is more than two orders of magnitude smaller than any known XMD with comparable metallicity.

Extraction of the respiratory signal from small-animal CT projections for a retrospective gating method

Energy Technology Data Exchange (ETDEWEB)

ChavarrIas, C; Vaquero, J J; Sisniega, A; RodrIguez-Ruano, A; Soto-Montenegro, M L; GarcIa-Barreno, P; Desco, M [Unidad de Medicina y CirugIa Experimental, Hospital General Universitario Gregorio Maranon, Anexo PsiquiatrIa, 1 Planta. C/Ibiza, 43. Madrid 28007 (Spain)

2008-09-07

We propose a retrospective respiratory gating algorithm to generate dynamic CT studies. To this end, we compared three different methods of extracting the respiratory signal from the projections of small-animal cone-beam computed tomography (CBCT) scanners. Given a set of frames acquired from a certain axial angle, subtraction of their average image from each individual frame produces a set of difference images. Pixels in these images have positive or negative values (according to the respiratory phase) in those areas where there is lung movement. The respiratory signals were extracted by analysing the shape of the histogram of these difference images: we calculated the first four central and non-central moments. However, only odd-order moments produced the desired breathing signal, as the even-order moments lacked information about the phase. Each of these curves was compared to a reference signal recorded by means of a pneumatic pillow. Given the similar correlation coefficients yielded by all of them, we selected the mean to implement our retrospective protocol. Respiratory phase bins were separated, reconstructed independently and included in a dynamic sequence, suitable for cine playback. We validated our method in five adult rat studies by comparing profiles drawn across the diaphragm dome, with and without retrospective respiratory gating. Results showed a sharper transition in the gated reconstruction, with an average slope improvement of 60.7%.

Extraction of the respiratory signal from small-animal CT projections for a retrospective gating method

International Nuclear Information System (INIS)

ChavarrIas, C; Vaquero, J J; Sisniega, A; RodrIguez-Ruano, A; Soto-Montenegro, M L; GarcIa-Barreno, P; Desco, M

2008-01-01

We propose a retrospective respiratory gating algorithm to generate dynamic CT studies. To this end, we compared three different methods of extracting the respiratory signal from the projections of small-animal cone-beam computed tomography (CBCT) scanners. Given a set of frames acquired from a certain axial angle, subtraction of their average image from each individual frame produces a set of difference images. Pixels in these images have positive or negative values (according to the respiratory phase) in those areas where there is lung movement. The respiratory signals were extracted by analysing the shape of the histogram of these difference images: we calculated the first four central and non-central moments. However, only odd-order moments produced the desired breathing signal, as the even-order moments lacked information about the phase. Each of these curves was compared to a reference signal recorded by means of a pneumatic pillow. Given the similar correlation coefficients yielded by all of them, we selected the mean to implement our retrospective protocol. Respiratory phase bins were separated, reconstructed independently and included in a dynamic sequence, suitable for cine playback. We validated our method in five adult rat studies by comparing profiles drawn across the diaphragm dome, with and without retrospective respiratory gating. Results showed a sharper transition in the gated reconstruction, with an average slope improvement of 60.7%

Respiratory

Science.gov (United States)

The words "respiratory" and "respiration" refer to the lungs and breathing. ... Boron WF. Organization of the respiratory system. In: Boron WF, Boulpaep EL, eds. Medical Physiology . 3rd ed. Philadelphia, PA: Elsevier; 2017:chap 26.

Effect of metabolic alkalosis on respiratory function in patients with chronic obstructive lung disease.

Science.gov (United States)

Bear, R.; Goldstein, M.; Phillipson, E.; Ho, M.; Hammeke, M.; Feldman, R.; Handelsman, S.; Halperin, M.

1977-01-01

Eleven instances of a mixed acid-base disorder consisting of chronic respiratory acidosis and metabolic alkalosis were recognized in eight patients with chronic obstructive lung disease and carbon dioxide retention. Correction of the metabolic alkalosis led to substantial improvement in blood gas values and clinical symptoms. Patients with mixed chronic respiratory acidosis and metabolic alkalosis constitute a common subgroup of patients with chronic obstructive lung disease and carbon dioxide retention; these patients benefit from correction of the metabolic alkalosis. PMID:21028

The respiratory microbiome and respiratory infections

NARCIS (Netherlands)

Unger, Stefan A.; Bogaert, Debby

2017-01-01

Despite advances over the past ten years lower respiratory tract infections still comprise around a fifth of all deaths worldwide in children under five years of age with the majority in low- and middle-income countries. Known risk factors for severe respiratory infections and poor chronic

Fuel cell-gas turbine hybrid system design part II: Dynamics and control

Science.gov (United States)

McLarty, Dustin; Brouwer, Jack; Samuelsen, Scott

2014-05-01

Fuel cell gas turbine hybrid systems have achieved ultra-high efficiency and ultra-low emissions at small scales, but have yet to demonstrate effective dynamic responsiveness or base-load cost savings. Fuel cell systems and hybrid prototypes have not utilized controls to address thermal cycling during load following operation, and have thus been relegated to the less valuable base-load and peak shaving power market. Additionally, pressurized hybrid topping cycles have exhibited increased stall/surge characteristics particularly during off-design operation. This paper evaluates additional control actuators with simple control methods capable of mitigating spatial temperature variation and stall/surge risk during load following operation of hybrid fuel cell systems. The novel use of detailed, spatially resolved, physical fuel cell and turbine models in an integrated system simulation enables the development and evaluation of these additional control methods. It is shown that the hybrid system can achieve greater dynamic response over a larger operating envelope than either individual sub-system; the fuel cell or gas turbine. Results indicate that a combined feed-forward, P-I and cascade control strategy is capable of handling moderate perturbations and achieving a 2:1 (MCFC) or 4:1 (SOFC) turndown ratio while retaining >65% fuel-to-electricity efficiency, while maintaining an acceptable stack temperature profile and stall/surge margin.

Dynamic Modeling Strategy for Flow Regime Transition in Gas-Liquid Two-Phase Flows

Directory of Open Access Journals (Sweden)

Xia Wang

2012-12-01

Full Text Available In modeling gas-liquid two-phase flows, the concept of flow regimes has been widely used to characterize the global interfacial structure of the flows. Nearly all constitutive relations that provide closures to the interfacial transfers in two-phase flow models, such as the two-fluid model, are flow regime dependent. Current nuclear reactor safety analysis codes, such as RELAP5, classify flow regimes using flow regime maps or transition criteria that were developed for steady-state, fully-developed flows. As two-phase flows are dynamic in nature, it is important to model the flow regime transitions dynamically to more accurately predict the two-phase flows. The present work aims to develop a dynamic modeling strategy to determine flow regimes in gas-liquid two-phase flows through introduction of interfacial area transport equations (IATEs within the framework of a two-fluid model. The IATE is a transport equation that models the interfacial area concentration by considering the creation of the interfacial area, fluid particle (bubble or liquid droplet disintegration, boiling and evaporation, and the destruction of the interfacial area, fluid particle coalescence and condensation. For flow regimes beyond bubbly flows, a two-group IATE has been proposed, in which bubbles are divided into two groups based on their size and shapes, namely group-1 and group-2 bubbles. A preliminary approach to dynamically identify the flow regimes is discussed, in which discriminators are based on the predicted information, such as the void fraction and interfacial area concentration. The flow regime predicted with this method shows good agreement with the experimental observations.

Demand for seasonal gas storage in northwest Europe until 2030. Simulation results with a dynamic model

International Nuclear Information System (INIS)

De Joode, J.; Oezdemir, Oe.

2010-01-01

The fact that depletion of indigenous gas production increases gas import dependency is widely known and accepted. However, there is considerable less attention for the implications of indigenous resource depletion for the provision of seasonal flexibility. The traditionally largest source of seasonal flexibility in Europe is indigenous gas production, mainly based in the Netherlands and the United Kingdom. With the depletion of indigenous sources the market increasingly needs to rely on other sources for seasonal flexibility, such as gas storage facilities. We investigate the future need for gas storage as a source for seasonal flexibility provision using a dynamic gas market model (GASTALE) in which different potential sources for seasonal flexibility - gas production, imports via pipeline, LNG imports and storage facilities - compete with each other in a market-based environment. The inclusion of seasonal flexibility properties in a gas market model allows a more complex analysis of seasonal flexibility issues than previously documented in literature. This is demonstrated in an analysis of the future demand for gas storage in northwestern Europe until 2030. Our results indicate that there is substantial need for additional gas storage facilities and thus supports current project proposals for new investment in gas storage facilities. (author)

Behavior and dynamics of bubble breakup in gas pipeline leaks and accidental subsea oil well blowouts.

Science.gov (United States)

Wang, Binbin; Socolofsky, Scott A; Lai, Chris C K; Adams, E Eric; Boufadel, Michel C

2018-06-01

Subsea oil well blowouts and pipeline leaks release oil and gas to the environment through vigorous jets. Predicting the breakup of the released fluids in oil droplets and gas bubbles is critical to predict the fate of petroleum compounds in the marine water column. To predict the gas bubble size in oil well blowouts and pipeline leaks, we observed and quantified the flow behavior and breakup process of gas for a wide range of orifice diameters and flow rates. Flow behavior at the orifice transitions from pulsing flow to continuous discharge as the jet crosses the sonic point. Breakup dynamics transition from laminar to turbulent at a critical value of the Weber number. Very strong pure gas jets and most gas/liquid co-flowing jets exhibit atomization breakup. Bubble sizes in the atomization regime scale with the jet-to-plume transition length scale and follow -3/5 power-law scaling for a mixture Weber number. Copyright © 2018 Elsevier Ltd. All rights reserved.

The effect of induced hypothermia on respiratory parameters in mechanically ventilated patients

NARCIS (Netherlands)

Aslami, Hamid; Binnekade, Jan M.; Horn, Janneke; Huissoon, Sandra; Juffermans, Nicole P.

2010-01-01

Aim: Mild hypothermia is increasingly applied in the intensive care unit. Knowledge on the effects of hypothermia on respiratory parameters during mechanical ventilation is limited. In this retrospective study, we describe the effect of hypothermia on gas exchange in patients cooled for 24 h after a

Optimization of a retrospective technique for respiratory-gated high speed micro-CT of free-breathing rodents

International Nuclear Information System (INIS)

Ford, Nancy L; Wheatley, Andrew R; Holdsworth, David W; Drangova, Maria

2007-01-01

The objective of this study was to develop a technique for dynamic respiratory imaging using retrospectively gated high-speed micro-CT imaging of free-breathing mice. Free-breathing C57Bl6 mice were scanned using a dynamic micro-CT scanner, comprising a flat-panel detector mounted on a slip-ring gantry. Projection images were acquired over ten complete gantry rotations in 50 s, while monitoring the respiratory motion in synchrony with projection-image acquisition. Projection images belonging to a selected respiratory phase were retrospectively identified and used for 3D reconstruction. The effect of using fewer gantry rotations-which influences both image quality and the ability to quantify respiratory function-was evaluated. Images reconstructed using unique projections from six or more gantry rotations produced acceptable images for quantitative analysis of lung volume, CT density, functional residual capacity and tidal volume. The functional residual capacity (0.15 ± 0.03 mL) and tidal volumes (0.08 ± 0.03 mL) measured in this study agree with previously reported measurements made using prospectively gated micro-CT and at higher resolution (150 μm versus 90 μm voxel spacing). Retrospectively gated micro-CT imaging of free-breathing mice enables quantitative dynamic measurement of morphological and functional parameters in the mouse models of respiratory disease, with scan times as short as 30 s, based on the acquisition of projection images over six gantry rotations

Optimization of a retrospective technique for respiratory-gated high speed micro-CT of free-breathing rodents

Energy Technology Data Exchange (ETDEWEB)

Ford, Nancy L [Department of Physics, Ryerson University, 350 Victoria Street, Toronto, Ontario M5B 2K3 (Canada); Wheatley, Andrew R [Imaging Research Laboratories, Robarts Research Institute, 100 Perth Drive, PO Box 5015, London, Ontario N6A 5K8 (Canada); Holdsworth, David W [Imaging Research Laboratories, Robarts Research Institute, 100 Perth Drive, PO Box 5015, London, Ontario N6A 5K8 (Canada); Drangova, Maria [Imaging Research Laboratories, Robarts Research Institute, 100 Perth Drive, PO Box 5015, London, Ontario N6A 5K8 (Canada)

2007-09-21

The objective of this study was to develop a technique for dynamic respiratory imaging using retrospectively gated high-speed micro-CT imaging of free-breathing mice. Free-breathing C57Bl6 mice were scanned using a dynamic micro-CT scanner, comprising a flat-panel detector mounted on a slip-ring gantry. Projection images were acquired over ten complete gantry rotations in 50 s, while monitoring the respiratory motion in synchrony with projection-image acquisition. Projection images belonging to a selected respiratory phase were retrospectively identified and used for 3D reconstruction. The effect of using fewer gantry rotations-which influences both image quality and the ability to quantify respiratory function-was evaluated. Images reconstructed using unique projections from six or more gantry rotations produced acceptable images for quantitative analysis of lung volume, CT density, functional residual capacity and tidal volume. The functional residual capacity (0.15 {+-} 0.03 mL) and tidal volumes (0.08 {+-} 0.03 mL) measured in this study agree with previously reported measurements made using prospectively gated micro-CT and at higher resolution (150 {mu}m versus 90 {mu}m voxel spacing). Retrospectively gated micro-CT imaging of free-breathing mice enables quantitative dynamic measurement of morphological and functional parameters in the mouse models of respiratory disease, with scan times as short as 30 s, based on the acquisition of projection images over six gantry rotations.

Is recurrent respiratory infection associated with allergic respiratory disease?

Science.gov (United States)

de Oliveira, Tiago Bittencourt; Klering, Everton Andrei; da Veiga, Ana Beatriz Gorini

2018-03-13

Respiratory infections cause high morbidity and mortality worldwide. This study aims to estimate the relationship between allergic respiratory diseases with the occurrence of recurrent respiratory infection (RRI) in children and adolescents. The International Study of Asthma and Allergies in Childhood questionnaire and a questionnaire that provides data on the history of respiratory infections and the use of antibiotics were used to obtain data from patients. The relationship between the presence of asthma or allergic rhinitis and the occurrence of respiratory infections in childhood was analyzed. We interviewed the caregivers of 531 children aged 0 to 15 years. The average age of participants was 7.43 years, with females accounting for 52.2%. This study found significant relationship between: presence of asthma or allergic rhinitis with RRI, with prevalence ratio (PR) of 2.47 (1.51-4.02) and 1.61 (1.34-1.93), respectively; respiratory allergies with use of antibiotics for respiratory problems, with PR of 5.32 (2.17-13.0) for asthma and of 1.64 (1.29-2.09) for allergic rhinitis; asthma and allergic rhinitis with diseases of the lower respiratory airways, with PR of 7.82 (4.63-13.21) and 1.65 (1.38-1.96), respectively. In contrast, no relationship between upper respiratory airway diseases and asthma and allergic rhinitis was observed, with PR of 0.71 (0.35-1.48) and 1.30 (0.87-1.95), respectively. RRI is associated with previous atopic diseases, and these conditions should be considered when treating children.

Plant accident dynamics of high-temperature reactors with direct gas turbine cycle

International Nuclear Information System (INIS)

Waloch, M.L.

1977-01-01

In the paper submitted, a one-dimensional accident simulation model for high-temperature reactors with direct-cycle gas turbine (single-cycle facilities) is described. The paper assesses the sudden failure of a gas duct caused by the double-ended break of one out of several parallel pipes before and behind the reactor for a non-integrated plant, leading to major loads in the reactor region, as well as the complete loss of vanes of the compressor for an integrated plant. The results of the calculations show especially high loads for the break of a hot-gas pipe immediately behind the flow restrictors of the reactor outlet, because of prolonged effects of pressure gradients in the reactor region and the maximum core differential pressure. A plant accident dynamics calculation therefore allows to find a compromise between the requirements of stable compressor operation, on the one hand, and small loads in the reactor in the course of an accident, on the other, by establishing in a co-ordinated manner the narrowing ratio of the flow restrictors. (GL) [de

Dynamic modeling of fixed-bed adsorption of flue gas using a variable mass transfer model

International Nuclear Information System (INIS)

Park, Jehun; Lee, Jae W.

2016-01-01

This study introduces a dynamic mass transfer model for the fixed-bed adsorption of a flue gas. The derivation of the variable mass transfer coefficient is based on pore diffusion theory and it is a function of effective porosity, temperature, and pressure as well as the adsorbate composition. Adsorption experiments were done at four different pressures (1.8, 5, 10 and 20 bars) and three different temperatures (30, 50 and 70 .deg. C) with zeolite 13X as the adsorbent. To explain the equilibrium adsorption capacity, the Langmuir-Freundlich isotherm model was adopted, and the parameters of the isotherm equation were fitted to the experimental data for a wide range of pressures and temperatures. Then, dynamic simulations were performed using the system equations for material and energy balance with the equilibrium adsorption isotherm data. The optimal mass transfer and heat transfer coefficients were determined after iterative calculations. As a result, the dynamic variable mass transfer model can estimate the adsorption rate for a wide range of concentrations and precisely simulate the fixed-bed adsorption process of a flue gas mixture of carbon dioxide and nitrogen.

SLOWLY ROTATING GAS-RICH GALAXIES IN MODIFIED NEWTONIAN DYNAMICS (MOND)

International Nuclear Information System (INIS)

Sánchez-Salcedo, F. J.; Martínez-García, E. E.; Hidalgo-Gámez, A. M.

2013-01-01

We have carried out a search for gas-rich dwarf galaxies that have lower rotation velocities in their outskirts than MOdified Newtonian Dynamics (MOND) predicts, so that the amplitude of their rotation curves cannot be fitted by arbitrarily increasing the mass-to-light ratio of the stellar component or by assuming additional undetected matter. With presently available data, the gas-rich galaxies UGC 4173, Holmberg II, ESO 245-G05, NGC 4861, and ESO 364-G029 deviate most from MOND predictions and, thereby, provide a sample of promising targets in testing the MOND framework. In the case of Holmberg II and NGC 4861, we find that their rotation curves are probably inconsistent with MOND, unless their inclinations and distances differ significantly from the nominal ones. The galaxy ESO 364-G029 is a promising target because its baryonic mass and rotation curve are similar to Holmberg II but presents a higher inclination. Deeper photometric and H I observations of ESO 364-G029, together with further decreasing systematic uncertainties, may provide a strong test to MOND.

Climate change and respiratory disease: European Respiratory Society position statement.

Science.gov (United States)

Ayres, J G; Forsberg, B; Annesi-Maesano, I; Dey, R; Ebi, K L; Helms, P J; Medina-Ramón, M; Windt, M; Forastiere, F

2009-08-01

Climate change will affect individuals with pre-existing respiratory disease, but the extent of the effect remains unclear. The present position statement was developed on behalf of the European Respiratory Society in order to identify areas of concern arising from climate change for individuals with respiratory disease, healthcare workers in the respiratory sector and policy makers. The statement was developed following a 2-day workshop held in Leuven (Belgium) in March 2008. Key areas of concern for the respiratory community arising from climate change are discussed and recommendations made to address gaps in knowledge. The most important recommendation was the development of more accurate predictive models for predicting the impact of climate change on respiratory health. Respiratory healthcare workers also have an advocatory role in persuading governments and the European Union to maintain awareness and appropriate actions with respect to climate change, and these areas are also discussed in the position statement.

The dynamics of the Frustrated Ising Lattice Gas

International Nuclear Information System (INIS)

Arenzon, J.J.; Stariolo, D.A.; Ricci-Tersenghi, F.

2000-04-01

The dynamical properties of a three dimensional model glass, the Frustrated Ising Lattice Gas (FILG) are studied by Monte Carlo simulations. We present results of compression experiments, where the chemical potential is either slowly or abruptly changed, as well as simulations at constant density. One-time quantities like density and two-times ones as correlations, responses and mean square displacements are measured, and the departure from equilibrium clearly characterized. The aging scenario, particularly in the case of the density autocorrelations, is reminiscent of spin glass phenomenology with violations of the fluctuation-dissipation theorem, typical of systems with one replica symmetry breaking. The FILG, as a valid on-lattice model of structural glasses, can be described with tools developed in spin glass theory and, being a finite dimensional model, can open the way for a systematic study of activated processes in glasses. (author)

The physiological challenges of the 1952 Copenhagen poliomyelitis epidemic and a renaissance in clinical respiratory physiology

Science.gov (United States)

West, John B.

2005-01-01

The 1952 Copenhagen poliomyelitis epidemic provided extraordinary challenges in applied physiology. Over 300 patients developed respiratory paralysis within a few weeks, and the ventilator facilities at the infectious disease hospital were completely overwhelmed. The heroic solution was to call upon 200 medical students to provide round-the-clock manual ventilation using a rubber bag attached to a tracheostomy tube. Some patients were ventilated in this way for several weeks. A second challenge was to understand the gas exchange and acid-base status of these patients. At the onset of the epidemic, the only measurement routinely available in the hospital was the carbon dioxide concentration in the blood, and the high values were initially misinterpreted as a mysterious “alkalosis.” However, pH measurements were quickly instituted, the PCO2 was shown to be high, and modern clinical respiratory acid-base physiology was born. Taking a broader view, the problems highlighted by the epidemic underscored the gap between recent advances made by physiologists and their application to the clinical environment. However, the 1950s ushered in a renaissance in clinical respiratory physiology. In 1950 the coverage of respiratory physiology in textbooks was often woefully inadequate, but the decade saw major advances in topics such as mechanics and gas exchange. An important development was the translation of the new knowledge from departments of physiology to the clinical setting. In many respects, this period was therefore the beginning of modern clinical respiratory physiology. PMID:16020437

Investigación de un brote respiratorio agudo por exposición a cloro gas en una piscina pública Investigation of an outbreak of acute respiratory illness due to exposure to chlorine gas in a public swimming pool

Directory of Open Access Journals (Sweden)

Diego Almagro Nievas

2008-06-01

Full Text Available Se diseñó un estudio de casos y controles para investigar el accidente químico ocurrido en una piscina pública en el verano de 2005 y describir los factores ambientales responsables, analizar el efecto del cloro gas y valorar la evolución clínica y funcional del aparato respiratorio. Las intervenciones fueron las siguientes: inspecciones ambientales, encuesta epidemiológica (variables sociodemográficas, ubicación en el momento del accidente, olor percibido y seguimiento clínico y espirométrico de la función respiratoria. Se encuestaron 65 casos y 48 controles. El suceso se produjo al mezclar accidentalmente ácido clorhídrico e hipoclorito sódico, lo que generó cloro gas. Los síntomas predominantes fueron tos y disnea. El riesgo de enfermar en niños era 10 veces mayor si tenían una enfermedad respiratoria previa y 4 veces superior si estaban a una distancia inferior a 40 m del lugar del accidente. Todos los casos evolucionaron hacia la curación, excepto uno que tenía antecedentes asmáticos.A case-control study was designed to investigate a chemical accident that occurred in a swimming-pool in the summer of 2005. The aim was to describe the environmental factors involved in the accident, to assess the effect of chlorine gas on the respiratory system, and to perform a clinical and spirometric follow-up. The following interventions were carried out: environmental inspection, epidemiologic survey (including sociodemographic variables, location at the time of the accident, perception of an abnormal smell, and clinical and spirometric outcomes to assess respiratory function. Sixty-five cases and 48 controls were identified and interviewed. The accident was produced by accidental admixture of hydrochloric acid with sodium hypochlorite resulting in chlorine gas release. The main clinical symptoms were dyspnea and cough. The risk of becoming ill was 10-fold higher in children with a previous lung disease and was 4-fold higher when

Partnering for optimal respiratory home care: physicians working with respiratory therapists to optimally meet respiratory home care needs.

Science.gov (United States)

Spratt, G; Petty, T L

2001-05-01

The need for respiratory care services continues to increase, reimbursement for those services has decreased, and cost-containment measures have increased the frequency of home health care. Respiratory therapists are well qualified to provide home respiratory care, reduce misallocation of respiratory services, assess patient respiratory status, identify problems and needs, evaluate the effect of the home setting, educate the patient on proper equipment use, monitor patient response to and complications of therapy, monitor equipment functioning, monitor for appropriate infection control procedures, make recommendations for changes to therapy regimen, and adjust therapy under the direction of the physician. Teamwork benefits all parties and offers cost and time savings, improved data collection and communication, higher job satisfaction, and better patient monitoring, education, and quality of life. Respiratory therapists are positioned to optimize treatment efficacy, maximize patient compliance, and minimize hospitalizations among patients receiving respiratory home care.

Gas and heat dynamics of a micro-scaled atmospheric pressure plasma reference jet

International Nuclear Information System (INIS)

Kelly, Seán; Golda, Judith; Schulz-von der Gathen, Volker; Turner, Miles M

2015-01-01

Gas and heat dynamics of the ‘Cooperation on Science and Technology (COST) Reference Microplasma Jet’ (COST-jet), a European lead reference device for low temperature atmospheric pressure plasma application, are investigated. Of particular interest to many biomedical application scenarios, the temperature characteristics of a surface impacted by the jet are revealed. Schlieren imaging, thermocouple measurements, infrared thermal imaging and numerical modelling are employed. Temperature spatial profiles in the gas domain reveal heating primarily of the helium fraction of the gas mixture. Thermocouple and model temporal data show a bounded exponential temperature growth described by a single characteristic time parameter to reach  ∼63% or (1-1/e) fraction of the temperature increase. Peak temperatures occurred in the gas domain where the carrier jet exits the COST-jet, with values ranging from ambient temperatures to in excess of 100 °C in ‘α-mode’ operation. In a horizontal orientation of the COST-jet a curved trajectory of the helium effluent at low gas flows results from buoyant forces. Gas mixture profiles reveal significant containment of the helium concentrations for a surface placed in close proximity to the COST-jet. Surface heating of a quartz plate follows a similar bounded exponential temporal temperature growth as device heating. Spatial profiles of surface heating are found to correlate strongly to the impacting effluent where peak temperatures occur in regions of maximum surface helium concentration. (paper)

Gas and heat dynamics of a micro-scaled atmospheric pressure plasma reference jet

Science.gov (United States)

Kelly, Seán; Golda, Judith; Turner, Miles M.; Schulz-von der Gathen, Volker

2015-11-01

Gas and heat dynamics of the ‘Cooperation on Science and Technology (COST) Reference Microplasma Jet’ (COST-jet), a European lead reference device for low temperature atmospheric pressure plasma application, are investigated. Of particular interest to many biomedical application scenarios, the temperature characteristics of a surface impacted by the jet are revealed. Schlieren imaging, thermocouple measurements, infrared thermal imaging and numerical modelling are employed. Temperature spatial profiles in the gas domain reveal heating primarily of the helium fraction of the gas mixture. Thermocouple and model temporal data show a bounded exponential temperature growth described by a single characteristic time parameter to reach  ∼63% or (1-1/e) fraction of the temperature increase. Peak temperatures occurred in the gas domain where the carrier jet exits the COST-jet, with values ranging from ambient temperatures to in excess of 100 °C in ‘α-mode’ operation. In a horizontal orientation of the COST-jet a curved trajectory of the helium effluent at low gas flows results from buoyant forces. Gas mixture profiles reveal significant containment of the helium concentrations for a surface placed in close proximity to the COST-jet. Surface heating of a quartz plate follows a similar bounded exponential temporal temperature growth as device heating. Spatial profiles of surface heating are found to correlate strongly to the impacting effluent where peak temperatures occur in regions of maximum surface helium concentration.

Veno-venous extracorporeal CO2 removal for the treatment of severe respiratory acidosis: pathophysiological and technical considerations.

Science.gov (United States)

Karagiannidis, Christian; Kampe, Kristin Aufm; Sipmann, Fernando Suarez; Larsson, Anders; Hedenstierna, Goran; Windisch, Wolfram; Mueller, Thomas

2014-06-17

While non-invasive ventilation aimed at avoiding intubation has become the modality of choice to treat mild to moderate acute respiratory acidosis, many severely acidotic patients (pH respiratory acidosis was only feasible when blood flow rates of 750 to 1000 mL/minute (19Fr catheter) were used. Maximal CO2-elimination was 146.1 ± 22.6 mL/minute, while pH increased from 7.13 ± 0.08 to 7.41 ± 0.07 (blood flow of 1000 mL/minute; sweep gas flow 16 L/minute). Accordingly, a sweep gas flow of 8 L/minute resulted in a maximal CO2-elimination rate of 138.0 ± 16.9 mL/minute. The 14.5Fr catheter allowed a maximum CO2 elimination rate of 77.9 mL/minute, which did not result in the normalization of pH. Veno-venous ECCO2R may serve as a treatment option for severe respiratory acidosis. In this porcine model, ECCO2R was most effective when using blood flow rates ranging between 750 and 1000 mL/minute, while an increase in sweep gas flow from 8 to 16 L/minute had less impact on ECCO2R in this setting.

Quantification of cardiorespiratory interactions based on joint symbolic dynamics.

Science.gov (United States)

Kabir, Muammar M; Saint, David A; Nalivaiko, Eugene; Abbott, Derek; Voss, Andreas; Baumert, Mathias

2011-10-01

Cardiac and respiratory rhythms are highly nonlinear and nonstationary. As a result traditional time-domain techniques are often inadequate to characterize their complex dynamics. In this article, we introduce a novel technique to investigate the interactions between R-R intervals and respiratory phases based on their joint symbolic dynamics. To evaluate the technique, electrocardiograms (ECG) and respiratory signals were recorded in 13 healthy subjects in different body postures during spontaneous and controlled breathing. Herein, the R-R time series were extracted from ECG and respiratory phases were obtained from abdomen impedance belts using the Hilbert transform. Both time series were transformed into ternary symbol vectors based on the changes between two successive R-R intervals or respiratory phases. Subsequently, words of different symbol lengths were formed and the correspondence between the two series of words was determined to quantify the interaction between cardiac and respiratory cycles. To validate our results, respiratory sinus arrhythmia (RSA) was further studied using the phase-averaged characterization of the RSA pattern. The percentage of similarity of the sequence of symbols, between the respective words of the two series determined by joint symbolic dynamics, was significantly reduced in the upright position compared to the supine position (26.4 ± 4.7 vs. 20.5 ± 5.4%, p cardiorespiratory interaction that is highly sensitive to the effects of orthostatic challenge.

Instantaneous Respiratory Estimation from Thoracic Impedance by Empirical Mode Decomposition

Directory of Open Access Journals (Sweden)

Fu-Tai Wang

2015-07-01

Full Text Available Impedance plethysmography provides a way to measure respiratory activity by sensing the change of thoracic impedance caused by inspiration and expiration. This measurement imposes little pressure on the body and uses the human body as the sensor, thereby reducing the need for adjustments as body position changes and making it suitable for long-term or ambulatory monitoring. The empirical mode decomposition (EMD can decompose a signal into several intrinsic mode functions (IMFs that disclose nonstationary components as well as stationary components and, similarly, capture respiratory episodes from thoracic impedance. However, upper-body movements usually produce motion artifacts that are not easily removed by digital filtering. Moreover, large motion artifacts disable the EMD to decompose respiratory components. In this paper, motion artifacts are detected and replaced by the data mirrored from the prior and the posterior before EMD processing. A novel intrinsic respiratory reconstruction index that considers both global and local properties of IMFs is proposed to define respiration-related IMFs for respiration reconstruction and instantaneous respiratory estimation. Based on the experiments performing a series of static and dynamic physical activates, our results showed the proposed method had higher cross correlations between respiratory frequencies estimated from thoracic impedance and those from oronasal airflow based on small window size compared to the Fourier transform-based method.

Gas dynamic design of the pipe line compressor with 90% efficiency. Model test approval

Science.gov (United States)

Galerkin, Y.; Rekstin, A.; Soldatova, K.

2015-08-01

Gas dynamic design of the pipe line compressor 32 MW was made for PAO SMPO (Sumy, Ukraine). The technical specification requires compressor efficiency of 90%. The customer offered favorable scheme - single-stage design with console impeller and axial inlet. The authors used the standard optimization methodology of 2D impellers. The original methodology of internal scroll profiling was used to minimize efficiency losses. Radically improved 5th version of the Universal modeling method computer programs was used for precise calculation of expected performances. The customer fulfilled model tests in a 1:2 scale. Tests confirmed the calculated parameters at the design point (maximum efficiency of 90%) and in the whole range of flow rates. As far as the authors know none of compressors have achieved such efficiency. The principles and methods of gas-dynamic design are presented below. The data of the 32 MW compressor presented by the customer in their report at the 16th International Compressor conference (September 2014, Saint- Petersburg) and later transferred to the authors.

Inverse problem and uncertainty quantification: application to compressible gas dynamics

International Nuclear Information System (INIS)

Birolleau, Alexandre

2014-01-01

This thesis deals with uncertainty propagation and the resolution of inverse problems together with their respective acceleration via Polynomial Chaos. The object of this work is to present a state of the art and a numerical analysis of this stochastic spectral method, in order to understand its pros and cons when tackling the probabilistic study of hydrodynamical instabilities in Richtmyer-Meshkov shock tube experiments. The first chapter is introductory and allows understanding the stakes of being able to accurately take into account uncertainties in compressible gas dynamics simulations. The second chapter is both an illustrative state of the art on generalized Polynomial Chaos and a full numerical analysis of the method keeping in mind the final application on hydrodynamical problems developing shocks and discontinuous solutions. In this chapter, we introduce a new method, naming iterative generalized Polynomial Chaos, which ensures a gain with respect to generalized Polynomial Chaos, especially with non smooth solutions. Chapter three is closely related to an accepted publication in Communication in Computational Physics. It deals with stochastic inverse problems and introduces bayesian inference. It also emphasizes the possibility of accelerating the bayesian inference thanks to iterative generalized Polynomial Chaos described in the previous chapter. Theoretical convergence is established and illustrated on several test-cases. The last chapter consists in the application of the above materials to a complex and ambitious compressible gas dynamics problem (Richtmyer-Meshkov shock tube configuration) together with a deepened study of the physico-numerical phenomenon at stake. Finally, in the appendix, we also present some interesting research paths we quickly tackled during this thesis. (author) [fr

Solvation of ions in the gas-phase: a molecular dynamics simulation

Science.gov (United States)

Cabarcos, Orlando M.; Lisy, James M.

1996-07-01

Molecular dynamics simulations have been performed on the collision between a cesium ion and a cluster of twenty methanol molecules. This process, generating a solvated ion, was studied over a range (1 to 25 eV) of eight collision energies. Preliminary analysis of this gas phase solvation has included the distribution of final ion cluster sizes, fragmentation patterns, solvation timescales and energetics. Two distinct patterns have emerged: a ballistic penetration of the neutral cluster at the higher collision energies and an evaporative evolution of the cluster ion at lower collision energies.

Molecular dynamics study of the influence of wall-gas interactions on heat flow in nanochannels

NARCIS (Netherlands)

Markvoort, Albert. J.; Hilbers, P.A.J.; Nedea, S.V.

2005-01-01

Especially at the nanometer scale interfaces play an important role. The effect of the wettability on the solid-liquid interface has already been studied with molecular dynamics. In this paper we study the dependence of wetting on the solid-gas interface for different density gases and investigate

Respiratory function in voluntary participating Patagonia sea lions in sternal recumbency

Directory of Open Access Journals (Sweden)

Andreas Fahlman

2016-11-01

Full Text Available We measured esophageal pressures (n=4, respiratory flow rates (n=5, and expired O2 and CO2 (n=4 in five adult Patagonia sea lions (Otaria flavescens, body mass range 94.3-286.0 kg during voluntary breaths while laying down. The data were used to estimate the dynamic specific lung compliance (sCL, cmH2O-1, the O2 consumption rate (VO2 and CO2 production rates (VCO2 during rest. Our results indicate that the resting tidal volume in Patagonia sea lions is approximately 47-73% of the estimated total lung capacity. The esophageal pressures indicated that expiration is passive during voluntary breaths. The average sCL of dolphins was 0.41±0.11 cmH2O−1, which is similar to those measured in anesthetized sea lions and awake cetaceans, and significantly higher as compared with humans (0.08 cmH2O−1. The average estimated and using breath-by-breath respirometry were 1.023 ± 0.327 L O2 min-1 (range: 0.695-1.514 L O2 min−1 and 0.777 ± 0.318 L CO2 min-1, (range: 0.510-1.235 L CO2 min-1, respectively, which is similar to previously published metabolic measurements from California and Steller sea lions using conventional flow-through respirometry. Our data provide end-tidal gas composition and provide novel data for respiratory physiology in pinnpeds, which may be important for clinical medicine and conservation efforts.

Accidental phosgene gas exposure: A review with background study of 10 cases

Directory of Open Access Journals (Sweden)

Arvind Kumar Vaish

2013-01-01

Full Text Available Here, authors present a review on clinical presentation and management of exposure of phosgene gas after reviewing the literature by searching with keywords phosgene exposure on Google, Cochrane, Embase and PubMed with a background of experience gained from 10 patients who were admitted to our institute after an accidental phosgene exposure in February 2011 nearby a city in India. Phosgene is a highly toxic gas, occupational workers may have accidental exposure. The gas can also be generated inadvertently during fire involving plastics and other chemicals and solvents containing chlorine, which is of concern to emergency responders. Phosgene inhalation may cause initially symptoms of respiratory tract irritation, patients feel fine thereafter, and then die of choking a day later because of build up of fluid in the lungs (delayed onset non-cardiogenic pulmonary edema. Phosgene exposure is associated with significant morbidity and mortality. Patients with a history of exposure should be admitted to the hospital for a minimum of 24 h for observation because of the potential for delayed onset respiratory failure and acute respiratory distress syndrome.

Insufficiency of Medical Care for Patients with Acute Respiratory Failure

Directory of Open Access Journals (Sweden)

A. V. Dats

2017-01-01

Full Text Available The purpose of the research: to analyze insufficiency of medical care for patients with acute respiratory failure in the ICU.Materials and methods. It was a retrospective study of 160 patients' medical records (age from 15 to 84 years with acute respiratory failure (ARF hospitalized in the ICUs of 24 regional and municipal hospitals of the Irkutsk Oblast. Medical records were provided by the Territorial Fund of Compulsory Medical Insurance of citizens of Irkutsk region.The results. The basic defects in conducting mechanical ventilation were associated with improper lung function evaluation, microbiological tests of sputum and radiology. ARF was not diagnosed in 32 of 160 ICU patients (20%. In 23% of cases the causes of ARF were not diagnosed. The greatest part of the defects in the treatment of patients with acute respiratory failure was found during the treatment of hypoxemia: no recovery of the respiratory tract patency, no prescription of oxygen for hypoxemia, no mechanical ventilation for persistent hypoxemia on the background of maximum oxygen supply and late switching to mechanical ventilation at the stage of hypoxic cardiac arrest.Conclusions. The use of pulse oximetry alone in the absence of arterial blood gas analysis in 98% of patients with acute respiratory failure and failure to perform the lung X-ray and/or MSCT imaging in 21% of patients were accompanied by a high level of undiagnosed acute respiratory distress syndrome (78%, lung contusion (60%, pulmonary embolism (40%, cardiogenic pulmonary edema (33%, and nosocomial pneumonia (28%. Defects of treatment of patients with ARF in 46% of cases were caused by inadequate management of hypoxemia associated with the recovery of the respiratory tract patency, prescription of oxygen, and mechanical ventilation. 

Imaging and dosimetric errors in 4D PET/CT-guided radiotherapy from patient-specific respiratory patterns: a dynamic motion phantom end-to-end study

Science.gov (United States)

Bowen, S R; Nyflot, M J; Hermann, C; Groh, C; Meyer, J; Wollenweber, S D; Stearns, C W; Kinahan, P E; Sandison, G A

2015-01-01

magnitude of errors was comparable during PET/CT imaging and treatment delivery without motion compensation. Errors were moderately mitigated during PET/CT imaging and significantly mitigated during RT delivery with motion compensation. This dynamic motion phantom end-to-end workflow provides a method for quality assurance of 4D PET/CT-guided radiotherapy, including evaluation of respiratory motion compensation methods during imaging and treatment delivery. PMID:25884892

Gas dynamic improvement of the axial compressor design for reduction of the flow non-uniformity level

Science.gov (United States)

Matveev, V. N.; Baturin, O. V.; Kolmakova, D. A.; Popov, G. M.

2017-01-01

Circumferential nonuniformity of gas flow is one of the main problems in the gas turbine engine. Usually, the flow circumferential nonuniformity appears near the annular frame located in the flow passage of the engine. The presence of circumferential nonuniformity leads to the increased dynamic stresses in the blade rows and the blade damage. The goal of this research was to find the ways of the flow non-uniformity reduction, which would not require a fundamental changing of the engine design. A new method for reducing the circumferential nonuniformity of the gas flow was proposed that allows the prediction of the pressure peak values of the rotor blades without computationally expensive CFD calculations.

Shock dynamics of weak imploding cylindrical and spherical shock waves with non-ideal gas effects

International Nuclear Information System (INIS)

Anand, R K

2013-01-01

The author (Anand 2012 Astrophys. Space Sci. 342 377–88) recently obtained jump relations across a shock front in non-ideal gas flow taking into consideration the equation of state for a non-ideal gas as given by Landau and Lifshitz. In this paper an analytical solution for one-dimensional adiabatic flow behind weak converging shock waves propagating in a non-ideal gas is obtained by using Whitham's (1974 Linear and Nonlinear Waves (New York: Wiley)) geometrical shock dynamics approach. The effects of an increase in (i) the propagation distance from the centre of convergence, (ii) the non-idealness parameter and (iii) the adiabatic index of the gas, on the shock velocity, pressure, density, particle velocity, adiabatic compressibility and the change in entropy across the shock front, are analyzed. The results provided a clear picture of whether and how the non-idealness parameter and the adiabatic index affect the flow field behind the imploding shock front. (paper)

The sensitivity and dynamic response of field ionization gas sensor based on ZnO nanorods

International Nuclear Information System (INIS)

Min Jiahua; Liang Xiaoyan; Wang Bin; Wang Linjun; Zhao Yue; Shi Weimin; Xia Yiben

2011-01-01

Field ionization gas sensors based on ZnO nanorods (50–300 nm in diameter, and 3–8 μm in length) with and without a buffer layer were fabricated, and the influence of the orientation of nano-ZnO on the ionization response of devices was discussed, including the sensitivity and dynamic response of the ZnO nanorods with preferential orientation. The results indicated that ZnO nanorods as sensor anode could dramatically decrease the breakdown voltage. The XRD and SEM images illustrated that nano-ZnO with a ZnO buffer layer displayed high c-axis orientation, which helps to significantly reduce the breakdown voltage. Device A based on ZnO nanorods with a ZnO buffer layer could distinguish toluene and acetone. The dynamic responses of device A to the NO x compounds presented the sensitivity of 0.045 ± 0.007 ppm/pA and the response speed within 17–40 s, and indicated a linear relationship between NO x concentration and current response at low NO x concentrations. In addition, the dynamic responses to benzene, isopropyl alcohol, ethanol, and methanol reveals that the device has higher sensitivity to gas with larger static polarizability and lower ionization energy.

Theoretical study of inspiratory flow waveforms during mechanical ventilation on pulmonary blood flow and gas exchange.

Science.gov (United States)

Niranjan, S C; Bidani, A; Ghorbel, F; Zwischenberger, J B; Clark, J W

1999-08-01

A lumped two-compartment mathematical model of respiratory mechanics incorporating gas exchange and pulmonary circulation is utilized to analyze the effects of square, descending and ascending inspiratory flow waveforms during mechanical ventilation. The effects on alveolar volume variation, alveolar pressure, airway pressure, gas exchange rate, and expired gas species concentration are evaluated. Advantages in ventilation employing a certain inspiratory flow profile are offset by corresponding reduction in perfusion rates, leading to marginal effects on net gas exchange rates. The descending profile provides better CO2 exchange, whereas the ascending profile is more advantageous for O2 exchange. Regional disparities in airway/lung properties create maldistribution of ventilation and a concomitant inequality in regional alveolar gas composition and gas exchange rates. When minute ventilation is maintained constant, for identical time constant disparities, inequalities in compliance yield pronounced effects on net gas exchange rates at low frequencies, whereas the adverse effects of inequalities in resistance are more pronounced at higher frequencies. Reduction in expiratory air flow (via increased airway resistance) reduces the magnitude of upstroke slope of capnogram and oxigram time courses without significantly affecting end-tidal expired gas compositions, whereas alterations in mechanical factors that result in increased gas exchanges rates yield increases in CO2 and decreases in O2 end-tidal composition values. The model provides a template for assessing the dynamics of cardiopulmonary interactions during mechanical ventilation by combining concurrent descriptions of ventilation, capillary perfusion, and gas exchange. Copyright 1999 Academic Press.

Gas exchange and heart rate in the harbour porpoise, Phocoena phocoena

DEFF Research Database (Denmark)

Reed, J.Z.; Chambers, C.; Hunter, C.J.

2000-01-01

a comparatively high minute rate of gas exchange. Oxygen consumption under these experimental conditions (247 +/- 13.8 ml O-2. min(-1)) was 1.9- fold higher than predicted by standard scaling relations. These data together with an estimate of the total oxygen stores predicted an aerobic dive limit of 5.4 min......The respiratory physiology, heart rates and metabolic rates of two captive juvenile male harbour porpoises (both 28 kg) were measured using a rapid-response respiratory gas analysis system in the laboratory. Breath-hold durations in the laboratory (12 +/- 0.3 s, mean +/- SEM) were shorter than...... field observations. although a few breath-holds of over 40 s were recorded. The mean percentage time spent submerged was 89 +/- 0.4%. Relative to similarly-sized terrestrial mammals, the respiratory frequency was low (4.9 +/- 0.19 breaths min(-1)) but with high tidal volumes (1.1 +/- 0.01 l), enabling...

Changes in blood lactate and respiratory gas exchange measures in sports with discontinuous load profiles.

Science.gov (United States)

Smekal, Gerhard; von Duvillard, Serge P; Pokan, Rochus; Tschan, Harald; Baron, Ramon; Hofmann, Peter; Wonisch, Manfred; Bachl, Norbert

2003-06-01

This study compares two different sport events (orienteering = OTC; tennis = TEC) with discontinuous load profiles and different activity/recovery patterns by means of blood lactate (LA), heart rate (HR), and respiratory gas exchange measures (RGME) determined via a portable respiratory system. During the TEC, 20 tennis-ranked male subjects [age: 26.0 (3.7) years; height: 181.0 (5.7) cm; weight: 73.2 (6.8) kg; maximal oxygen consumption (VO(2)max): 57.3 (5.1) ml.kg(-1).min(-1)] played ten matches of 50 min. During the OTC, 11 male members of the Austrian National Team [age: 23.5 (3.9) years; height: 183.6 (6.8) cm; weight: 72.4 (3.9) kg; VO(2)max: 67.9 (3.8) ml.kg(-1).min(-1)] performed a simulated OTC (six sections; average length: 10.090 m). In both studies data from the maximal treadmill tests (TT) were used as reference values for the comparison of energy expenditure of OTC and TEC. During TEC, the average VO(2) was considerably lower [29.1 (5.6) ml(.)kg(-1.)min(-1)] or 51.1 (10.9)% of VO(2)max and 64.8.0 (13.3)% of VO(2) determined at the individual anaerobic threshold (IAT) on the TT. The short high-intensity periods (activity/recovery = 1/6) did not result in higher LA levels [average LA of games: 2.07 (0.9) mmol.l(-1)]. The highest average VO(2 )value for a whole game was 47.8 ml.kg(-1.)min(-1) and may provide a reference for energy demands required to sustain high-intensity periods of tennis predominantly via aerobic mechanism of energy delivery. During OTC, we found an average VO(2) of 56.4 (4.5) ml.kg(-1).min(-1) or 83.0 (3.8)% of VO(2)max and 94.6 (5.2)% of VO(2) at IAT. In contrast to TEC, LA were relatively high [5.16 (1.5) mmol.l(-1)) although the average VO(2) was significantly lower than VO(2) at IAT. Our data suggest that portable RGEM provides valuable information concerning the energy expenditure in sports that cannot be interpreted from LA or HR measures alone. Portable RGEM systems provide valuable assessment of under- or over-estimation of

Respiratory mechanics and plasma levels of tumor necrosis factor alpha and interleukin 6 are affected by gas humidification during mechanical ventilation in dogs.

Science.gov (United States)

Hernández-Jiménez, Claudia; García-Torrentera, Rogelio; Olmos-Zúñiga, J Raúl; Jasso-Victoria, Rogelio; Gaxiola-Gaxiola, Miguel O; Baltazares-Lipp, Matilde; Gutiérrez-González, Luis H

2014-01-01

The use of dry gases during mechanical ventilation has been associated with the risk of serious airway complications. The goal of the present study was to quantify the plasma levels of TNF-alpha and IL-6 and to determine the radiological, hemodynamic, gasometric, and microscopic changes in lung mechanics in dogs subjected to short-term mechanical ventilation with and without humidification of the inhaled gas. The experiment was conducted for 24 hours in 10 dogs divided into two groups: Group I (n = 5), mechanical ventilation with dry oxygen dispensation, and Group II (n = 5), mechanical ventilation with oxygen dispensation using a moisture chamber. Variance analysis was used. No changes in physiological, hemodynamic, or gasometric, and radiographic constants were observed. Plasma TNF-alpha levels increased in group I, reaching a maximum 24 hours after mechanical ventilation was initiated (ANOVA p = 0.77). This increase was correlated to changes in mechanical ventilation. Plasma IL-6 levels decreased at 12 hours and increased again towards the end of the study (ANOVA p>0.05). Both groups exhibited a decrease in lung compliance and functional residual capacity values, but this was more pronounced in group I. Pplat increased in group I (ANOVA p = 0.02). Inhalation of dry gas caused histological lesions in the entire respiratory tract, including pulmonary parenchyma, to a greater extent than humidified gas. Humidification of inspired gases can attenuate damage associated with mechanical ventilation.

Respiratory mechanics and plasma levels of tumor necrosis factor alpha and interleukin 6 are affected by gas humidification during mechanical ventilation in dogs.

Directory of Open Access Journals (Sweden)

Claudia Hernández-Jiménez

Full Text Available The use of dry gases during mechanical ventilation has been associated with the risk of serious airway complications. The goal of the present study was to quantify the plasma levels of TNF-alpha and IL-6 and to determine the radiological, hemodynamic, gasometric, and microscopic changes in lung mechanics in dogs subjected to short-term mechanical ventilation with and without humidification of the inhaled gas. The experiment was conducted for 24 hours in 10 dogs divided into two groups: Group I (n = 5, mechanical ventilation with dry oxygen dispensation, and Group II (n = 5, mechanical ventilation with oxygen dispensation using a moisture chamber. Variance analysis was used. No changes in physiological, hemodynamic, or gasometric, and radiographic constants were observed. Plasma TNF-alpha levels increased in group I, reaching a maximum 24 hours after mechanical ventilation was initiated (ANOVA p = 0.77. This increase was correlated to changes in mechanical ventilation. Plasma IL-6 levels decreased at 12 hours and increased again towards the end of the study (ANOVA p>0.05. Both groups exhibited a decrease in lung compliance and functional residual capacity values, but this was more pronounced in group I. Pplat increased in group I (ANOVA p = 0.02. Inhalation of dry gas caused histological lesions in the entire respiratory tract, including pulmonary parenchyma, to a greater extent than humidified gas. Humidification of inspired gases can attenuate damage associated with mechanical ventilation.

Determination of dynamic variations in the optical properties of graphene oxide in response to gas exposure based on thin-film interference.

Science.gov (United States)

Tabassum, Shawana; Dong, Liang; Kumar, Ratnesh

2018-03-05

We present an effective yet simple approach to study the dynamic variations in optical properties (such as the refractive index (RI)) of graphene oxide (GO) when exposed to gases in the visible spectral region, using the thin-film interference method. The dynamic variations in the complex refractive index of GO in response to exposure to a gas is an important factor affecting the performance of GO-based gas sensors. In contrast to the conventional ellipsometry, this method alleviates the need of selecting a dispersion model from among a list of model choices, which is limiting if an applicable model is not known a priori. In addition, the method used is computationally simpler, and does not need to employ any functional approximations. Further advantage over ellipsometry is that no bulky optics is required, and as a result it can be easily integrated into the sensing system, thereby allowing the reliable, simple, and dynamic evaluation of the optical performance of any GO-based gas sensor. In addition, the derived values of the dynamically changing RI values of the GO layer obtained from the method we have employed are corroborated by comparing with the values obtained from ellipsometry.

Respiratory mechanics

CERN Document Server

Wilson, Theodore A

2016-01-01

This book thoroughly covers each subfield of respiratory mechanics: pulmonary mechanics, the respiratory pump, and flow. It presents the current understanding of the field and serves as a guide to the scientific literature from the golden age of respiratory mechanics, 1960 - 2010. Specific topics covered include the contributions of surface tension and tissue forces to lung recoil, the gravitational deformation of the lung, and the interdependence forces that act on pulmonary airways and blood vessels. The geometry and kinematics of the ribs is also covered in detail, as well as the respiratory action of the external and internal intercostal muscles, the mechanics of the diaphragm, and the quantitative compartmental models of the chest wall is also described. Additionally, flow in the airways is covered thoroughly, including the wave-speed and viscous expiratory flow-limiting mechanisms; convection, diffusion and the stationary front; and the distribution of ventilation. This is an ideal book for respiratory ...

Respiratory signal analysis of liver cancer patients with respiratory-gated radiation therapy

International Nuclear Information System (INIS)

Kang, Dong Im; Jung, Sang Hoon; Kim, Chul Jong; Park, Hee Chul; Choi, Byung Ki

2015-01-01

External markers respiratory movement measuring device (RPM; Real-time Position Management, Varian Medical System, USA) Liver Cancer Radiation Therapy Respiratory gated with respiratory signal with irradiation time and the actual research by analyzing the respiratory phase with the breathing motion measurement device respiratory tuning evaluate the accuracy of radiation therapy May-September 2014 Novalis Tx. (Varian Medical System, USA) and liver cancer radiotherapy using respiratory gated RPM (Duty Cycle 20%, Gating window 40%-60%) of 16 patients who underwent total when recording the analyzed respiratory movement. After the breathing motion of the external markers recorded on the RPM was reconstructed by breathing through the acts phase analysis, for Beam-on Time and Duty Cycle recorded by using the reconstructed phase breathing breathing with RPM gated the prediction accuracy of the radiation treatment analysis and analyzed the correlation between prediction accuracy and Duty Cycle in accordance with the reproducibility of the respiratory movement. Treatment of 16 patients with respiratory cycle during the actual treatment plan was analyzed with an average difference -0.03 seconds (range -0.50 seconds to 0.09 seconds) could not be confirmed statistically significant difference between the two breathing (p = 0.472). The average respiratory period when treatment is 4.02 sec (0.71 sec), the average value of the respiratory cycle of the treatment was characterized by a standard deviation 7.43% (range 2.57 to 19.20%). Duty Cycle is that the actual average 16.05% (range 13.78 to 17.41%), average 56.05 got through the acts of the show and then analyzed% (range 39.23 to 75.10%) is planned in respiratory research phase (40% to 60%) in was confirmed. The investigation on the correlation between the ratio Duty Cycle and planned respiratory phase and the standard deviation of the respiratory cycle was analyzed in each -0.156 (p = 0.282) and -0.385 (p = 0.070). This study is

Incidence of respiratory viruses in Peruvian children with acute respiratory infections.

Science.gov (United States)

del Valle Mendoza, Juana; Cornejo-Tapia, Angela; Weilg, Pablo; Verne, Eduardo; Nazario-Fuertes, Ronald; Ugarte, Claudia; del Valle, Luis J; Pumarola, Tomás

2015-06-01

Acute respiratory infections are responsible for high morbi-mortality in Peruvian children. However, the etiological agents are poorly identified. This study, conducted during the pandemic outbreak of H1N1 influenza in 2009, aims to determine the main etiological agents responsible for acute respiratory infections in children from Lima, Peru. Nasopharyngeal swabs collected from 717 children with acute respiratory infections between January 2009 and December 2010 were analyzed by multiplex RT-PCR for 13 respiratory viruses: influenza A, B, and C virus; parainfluenza virus (PIV) 1, 2, 3, and 4; and human respiratory syncytial virus (RSV) A and B, among others. Samples were also tested with direct fluorescent-antibodies (DFA) for six respiratory viruses. RT-PCR and DFA detected respiratory viruses in 240 (33.5%) and 85 (11.9%) cases, respectively. The most common etiological agents were RSV-A (15.3%), followed by influenza A (4.6%), PIV-1 (3.6%), and PIV-2 (1.8%). The viruses identified by DFA corresponded to RSV (5.9%) and influenza A (1.8%). Therefore, respiratory syncytial viruses (RSV) were found to be the most common etiology of acute respiratory infections. The authors suggest that active surveillance be conducted to identify the causative agents and improve clinical management, especially in the context of possible circulation of pandemic viruses. © 2015 Wiley Periodicals, Inc.

The microbiota of the respiratory tract : Gatekeeper to respiratory health

NARCIS (Netherlands)

Man, Wing Ho; De Steenhuijsen Piters, Wouter A.A.; Bogaert, Debby

2017-01-01

The respiratory tract is a complex organ system that is responsible for the exchange of oxygen and carbon dioxide. The human respiratory tract spans from the nostrils to the lung alveoli and is inhabited by niche-specific communities of bacteria. The microbiota of the respiratory tract probably acts

Interactions of Delta Shock Waves for Zero-Pressure Gas Dynamics with Energy Conservation Law

OpenAIRE

Wei Cai; Yanyan Zhang

2016-01-01

We study the interactions of delta shock waves and vacuum states for the system of conservation laws of mass, momentum, and energy in zero-pressure gas dynamics. The Riemann problems with initial data of three piecewise constant states are solved case by case, and four different configurations of Riemann solutions are constructed. Furthermore, the numerical simulations completely coinciding with theoretical analysis are shown.

Reactive molecular dynamic simulations on the gas separation performance of porous graphene membrane.

Science.gov (United States)

Esfandiarpoor, Somaye; Fazli, Mostafa; Ganji, Masoud Darvish

2017-11-29

The separation of gases molecules with similar diameter and shape is an important area of research. For example, the major challenge to set up sweeping carbon dioxide capture and storage (CCS) in power plants is the energy requisite to separate the CO 2 from flue gas. Porous graphene has been proposed as superior material for highly selective membranes for gas separation. Here we design some models of porous graphene with different sizes and shape as well as employ double layers porous graphene for efficient CO 2 /H 2 separation. The selectivity and permeability of gas molecules through various nanopores were investigated by using the reactive molecular dynamics simulation which considers the bond forming/breaking mechanism for all atoms. Furthermore, it uses a geometry-dependent charge calculation scheme that accounts appropriately for polarization effect which can play an important role in interacting systems. It was found that H-modified porous graphene membrane with pore diameter (short side) of about 3.75 Å has excellent selectivity for CO 2 /H 2 separation. The mechanism of gas penetration through the sub-nanometer pore was presented for the first time. The accuracy of MD simulation results validated by valuable DFT method. The present findings show that reactive MD simulation can propose an economical means of separating gases mixture.

Gas Dynamics in Planetary Nebulae: From Macro-structures to FLIERs

Science.gov (United States)

Perinotto, Mario

2000-10-01

Purpose of this paper is to clarify how Planetary Nebulae (PNe) are very interesting laboratories to study cosmic gas dynamics. I first recall the history of PNe which are generated from low and intermediate mass stars through successive mass loss processes starting in the Reg Giant phase of evolution and continuing also after the termination of the pulsed AGB phase, where most of the nebular mass is believed to be ejected. The correponding stellar winds are the ingredients of the nebula. Their initial properties and subsequent mutual interactions, under the action of the evolving stellar radiation field, are responsible for the properties of the nebula. The observed structures of PNe are considered in detail. Larger scale macroscopic structures (MACS) are examined separately from quite smaller scale microscopic structures (MICS). The formation of MACS, at least in cases of round to moderately elliptical PNe, is shown to be reasonably well understood in terms of existing hydrodynamical models. Considering the kinematical behaviour, MICS can be separated into FLIERs (Fast Low Ionization Emitting Regions) and SLOWERs (slowly moving). Attention is focussed on FLIERs and on the proposed mechanisms to interpret them. Recent observations with the Hubble Space Telescope have provided us with a wealth of detailed (subarcsec) information on the nebular structures. The inner structure of FLIERs is here illustrated to consist of substructures of various shapes with an high degree of individually from object to object, also within the same PN. These new data call for deeper thoretical efforts to solve the problems of cosmic gas dynamics, posed by their observed properties. An ample account is given of the most relevant original works, in an effort to allow the non specialist reader to quickly become acquainted with the status of art in the various aspects of the subject.

Dynamical Behavior of Multi-Robot Systems Using Lattice Gas Automata

Energy Technology Data Exchange (ETDEWEB)

Cameron, S.M.; Robinett, R.; Stantz, K.M.; Trahan, M.W.; Wagner, J.S.

1999-03-11

Recent attention has been given to the deployment of an adaptable sensor array realized by multi-robotic systems. Our group has been studying the collective behavior of autonomous, multi-agent systems and their applications in the area of remote-sensing and emerging threats. To accomplish such tasks, an interdisciplinary research effort at Sandia National Laboratories are conducting tests in the fields of sensor technology, robotics, and multi-robotic and multi-agents architectures. Our goal is to coordinate a constellation of point sensors that optimizes spatial coverage and multivariate signal analysis using unmanned robotic vehicles (e.g., RATLERs, Robotic All-ten-sin Lunar Exploration Rover-class vehicles). Overall design methodology is to evolve complex collective behaviors realized through simple interaction (kinetic) physics and artificial intelligence to enable real-time operational responses to emerging threats. This paper focuses on our recent work understanding the dynamics of many-body systems using the physics-based hydrodynamic model of lattice gas automata. Three design features are investigated. One, for single-speed robots, a hexagonal nearest-neighbor interaction topology is necessary to preserve standard hydrodynamic flow. Two, adaptability, defined by the swarm's deformation rate, can be controlled through the hydrodynamic viscosity term, which, in turn, is defined by the local robotic interaction rules. Three, due to the inherent non-linearity of the dynamical equations describing large ensembles, development of stability criteria ensuring convergence to equilibrium states is developed by scaling information flow rates relative to a swarm's hydrodynamic flow rate. An initial test case simulates a swarm of twenty-five robots that maneuvers past an obstacle while following a moving target. A genetic algorithm optimizes applied nearest-neighbor forces in each of five spatial regions distributed over the simulation domain. Armed with

Respiratory Home Health Care

Science.gov (United States)

... Us Home > Healthy Living > Living With Lung Disease > Respiratory Home Health Care Font: Aerosol Delivery Oxygen Resources ... Teenagers Living With Lung Disease Articles written by Respiratory Experts Respiratory Home Health Care Respiratory care at ...

The method of the gas-dynamic centrifugal compressor stage characteristics recalculation for variable rotor rotational speeds and the rotation angle of inlet guide vanes blades if the kinematic and dynamic similitude conditions are not met

Science.gov (United States)

Vanyashov, A. D.; Karabanova, V. V.

2017-08-01

A mathematical description of the method for obtaining gas-dynamic characteristics of a centrifugal compressor stage is proposed, taking into account the control action by varying the rotor speed and the angle of rotation of the guide vanes relative to the "basic" characteristic, if the kinematic and dynamic similitude conditions are not met. The formulas of the correction terms for the non-dimensional coefficients of specific work, consumption and efficiency are obtained. A comparative analysis of the calculated gas-dynamic characteristics of a high-pressure centrifugal stage with experimental data is performed.

Proximity to natural gas wells and reported health status: results of a household survey in Washington County, Pennsylvania.

Science.gov (United States)

Rabinowitz, Peter M; Slizovskiy, Ilya B; Lamers, Vanessa; Trufan, Sally J; Holford, Theodore R; Dziura, James D; Peduzzi, Peter N; Kane, Michael J; Reif, John S; Weiss, Theresa R; Stowe, Meredith H

2015-01-01

Little is known about the environmental and public health impact of unconventional natural gas extraction activities, including hydraulic fracturing, that occur near residential areas. Our aim was to assess the relationship between household proximity to natural gas wells and reported health symptoms. We conducted a hypothesis-generating health symptom survey of 492 persons in 180 randomly selected households with ground-fed wells in an area of active natural gas drilling. Gas well proximity for each household was compared with the prevalence and frequency of reported dermal, respiratory, gastrointestinal, cardiovascular, and neurological symptoms. The number of reported health symptoms per person was higher among residents living 2 km from the nearest gas well (mean ± SD, 1.60 ± 2.14; p = 0.0002). In a model that adjusted for age, sex, household education, smoking, awareness of environmental risk, work type, and animals in house, reported skin conditions were more common in households 2 km from the nearest gas well (odds ratio = 4.1; 95% CI: 1.4, 12.3; p = 0.01). Upper respiratory symptoms were also more frequently reported in persons living in households gas wells (39%) compared with households 1-2 km or > 2 km from the nearest well (31 and 18%, respectively) (p = 0.004). No equivalent correlation was found between well proximity and other reported groups of respiratory, neurological, cardiovascular, or gastrointestinal conditions. Although these results should be viewed as hypothesis generating, and the population studied was limited to households with a ground-fed water supply, proximity of natural gas wells may be associated with the prevalence of health symptoms including dermal and respiratory conditions in residents living near natural gas extraction activities. Further study of these associations, including the role of specific air and water exposures, is warranted.

Dynamic simulation of a furnace of steam reforming of natural gas

International Nuclear Information System (INIS)

Acuna, A; Fuentes, C; Smith, C A

1999-01-01

Steam reforming of natural gas is a very important industrial process in refineries and ammonia and methanol plants. Hydrogen is produced by reforming methane with steam. This hydrogen is essential in the hydro-treating process in the refineries thus, it is important to supervise and control the performance of the hydrogen plant. Mathematical models of refineries and chemical plants are used to simulate the behavior of the process units. However, the models especially of reactors like reformers are not very reliable. This paper presents a dynamic model of a furnace-reactor. The simulation results are validated with industrial data

Effects of Increased Respiratory Resistance on Maximal O2 Uptake and Anaerobic Threshold during Incremental Exercise Tests

OpenAIRE

ÖZÇELİK, Oğuz

2014-01-01

This study was undertaken to assess whether maximal O2 uptake (VO2max) can be used as an index of measuring aerobic capacity under the condition of increased respiratory resistance. Seven male subjects performed two incremental exercise tests on a cycle ergometer on different days: one control (C) and one breathing through an 8 mm bore diameter respiratory resistance (R). Ventilatory and gas exchange responses were measured with a turbine volume transducer and mass spectrometry, and processed...

The Respiratory Impedance in an Asymmetric Model of the Lung Structure

Directory of Open Access Journals (Sweden)

Robin De Keyser

2011-01-01

Full Text Available This paper presents a model of the respiratory tree as a recurrent, but asymmetric, structure. The intrinsic properties posed by such a system lead to a multi-fractal structure, i.e. a non-integer order model of the total impedance. The fractional order behavior of the asymmetric tree simulated as a dynamic system is assessed by means of Bode plots, on a wide range of frequencies. The results indicate than in a specific frequency range, both the symmetric
and asymmetric representation of the respiratory tree lead to similar values in the impedance.

Modelling the Dynamic Interaction Power System Lamp - Application to High Pressure Mercury Gas Discharge Lamps

Directory of Open Access Journals (Sweden)

ZIANE, M.

2007-11-01

Full Text Available The aim of this paper is to study the dynamic behaviour of a plant constituted by an electrical power system and a gas discharge lamp, this latter, increasingly used in street lighting, remains a nonlinear load element. Various approaches are used to represent it, one is the approximation of the discharge represented by a hot "channel", which verifies the assumption of local thermodynamic equilibrium [LTE] or the polynomial form of the conductance variation. A calculation procedure, based on "channel" approximation of the high pressure mercury (HPM gas-discharge lamp, is developed to determine the physical and electric magnitudes, which characterize the dynamic behavior of the couple "lamp-electrical power system". The evolution of the lamp properties when principal parameters of the discharge (pressure of mercury, voltage supply, frequency are varying were studied and analyzed. We show the concordance between simulation, calculations and measurements for electric, energetic or irradiative characteristics. The model reproduces well the evolution of properties of the supply when principal parameters of the discharge vary.

Interactions of Delta Shock Waves for Zero-Pressure Gas Dynamics with Energy Conservation Law

Directory of Open Access Journals (Sweden)

Wei Cai

2016-01-01

Full Text Available We study the interactions of delta shock waves and vacuum states for the system of conservation laws of mass, momentum, and energy in zero-pressure gas dynamics. The Riemann problems with initial data of three piecewise constant states are solved case by case, and four different configurations of Riemann solutions are constructed. Furthermore, the numerical simulations completely coinciding with theoretical analysis are shown.

Sigh rate and respiratory variability during mental load and sustained attention.

Science.gov (United States)

Vlemincx, Elke; Taelman, Joachim; De Peuter, Steven; Van Diest, Ilse; Van den Bergh, Omer

2011-01-01

Spontaneous breathing consists of substantial correlated variability: Parameters characterizing a breath are correlated with parameters characterizing previous and future breaths. On the basis of dynamic system theory, negative emotion states are predicted to reduce correlated variability whereas sustained attention is expected to reduce total respiratory variability. Both are predicted to evoke sighing. To test this, respiratory variability and sighing were assessed during a baseline, stressful mental arithmetic task, nonstressful sustained attention task, and recovery in between tasks. For respiration rate (excluding sighs), reduced total variability was found during the attention task, whereas correlated variation was reduced during mental load. Sigh rate increased during mental load and during recovery from the attention task. It is concluded that mental load and task-related attention show specific patterns in respiratory variability and sigh rate. Copyright © 2010 Society for Psychophysiological Research.

ERS/ATS workshop report on respiratory health effects of household air pollution.

Science.gov (United States)

Sood, Akshay; Assad, Nour A; Barnes, Peter J; Churg, Andrew; Gordon, Stephen B; Harrod, Kevin S; Irshad, Hammad; Kurmi, Om P; Martin, William J; Meek, Paula; Mortimer, Kevin; Noonan, Curtis W; Perez-Padilla, Rogelio; Smith, Kirk R; Tesfaigzi, Yohannes; Ward, Tony; Balmes, John

2018-01-01

Exposure to household air pollution (HAP) from solid fuel combustion affects almost half of the world population. Adverse respiratory outcomes such as respiratory infections, impaired lung growth and chronic obstructive pulmonary disease have been linked to HAP exposure. Solid fuel smoke is a heterogeneous mixture of various gases and particulates. Cell culture and animal studies with controlled exposure conditions and genetic homogeneity provide important insights into HAP mechanisms. Impaired bacterial phagocytosis in exposed human alveolar macrophages possibly mediates several HAP-related health effects. Lung pathological findings in HAP-exposed individuals demonstrate greater small airways fibrosis and less emphysema compared with cigarette smokers. Field studies using questionnaires, air pollution monitoring and/or biomarkers are needed to better establish human risks. Some, but not all, studies suggest that improving cookstove efficiency or venting emissions may be associated with reduced respiratory symptoms, lung function decline in women and severe pneumonia in children. Current studies focus on fuel switching, stove technology replacements or upgrades and air filter devices. Several governments have initiated major programmes to accelerate the upgrade from solid fuels to clean fuels, particularly liquid petroleum gas, which provides research opportunities for the respiratory health community. Copyright ©ERS 2018.

Non-invasive and non-intrusive gas flow measurement based on the dynamic thermal characteristics of a pipeline

Science.gov (United States)

Fan, Zichuan; Cai, Maolin; Xu, Weiqing

2012-10-01

This paper proposes a non-intrusive and non-invasive method for measuring the gas flow rate in pneumatic industry. A heater unit is fixed on the partial circumference of the external wall of a pipeline and emits specific thermal pulses in a predetermined mode. Two sensors attached to the external wall detect the upstream temperature, and the gas flow can be measured according to the relationship between the flow rate and the dynamic thermal characteristics of the pipeline. To determine the preferable relationship, the temperature field model of the measurement system is built. Then, based on the measurement modes and the corresponding simulations, the objective functions for the gas flow specified on different dynamic thermal characteristics are established. Additionally, the minimum measurement time of the method, named reference time scale, is proposed. Further, robustness tests of the measurement method are derived by considering the influences of multiple factors on the objective functions. The experiments confirm that this method does not need to open the pipeline and disturb the flow regime in order to obtain the data; this method also avoids the typical time-consuming and complex operations, resists ambient temperature disturbance and achieves approximately acceptable results.

Non-invasive and non-intrusive gas flow measurement based on the dynamic thermal characteristics of a pipeline

International Nuclear Information System (INIS)

Fan, Zichuan; Cai, Maolin; Xu, Weiqing

2012-01-01

This paper proposes a non-intrusive and non-invasive method for measuring the gas flow rate in pneumatic industry. A heater unit is fixed on the partial circumference of the external wall of a pipeline and emits specific thermal pulses in a predetermined mode. Two sensors attached to the external wall detect the upstream temperature, and the gas flow can be measured according to the relationship between the flow rate and the dynamic thermal characteristics of the pipeline. To determine the preferable relationship, the temperature field model of the measurement system is built. Then, based on the measurement modes and the corresponding simulations, the objective functions for the gas flow specified on different dynamic thermal characteristics are established. Additionally, the minimum measurement time of the method, named reference time scale, is proposed. Further, robustness tests of the measurement method are derived by considering the influences of multiple factors on the objective functions. The experiments confirm that this method does not need to open the pipeline and disturb the flow regime in order to obtain the data; this method also avoids the typical time-consuming and complex operations, resists ambient temperature disturbance and achieves approximately acceptable results. (paper)

Quantitative Analysis of Bioactive Compounds from Aromatic Plants by Means of Dynamic Headspace Extraction and Multiple Headspace Extraction-Gas Chromatography-Mass Spectrometry

NARCIS (Netherlands)

Omar, Jone; Olivares, Maitane; Alonso, Ibone; Vallejo, Asier; Aizpurua-Olaizola, Oier; Etxebarria, Nestor

2016-01-01

Seven monoterpenes in 4 aromatic plants (sage, cardamom, lavender, and rosemary) were quantified in liquid extracts and directly in solid samples by means of dynamic headspace-gas chromatography-mass spectrometry (DHS-GC-MS) and multiple headspace extraction-gas chromatography-mass spectrometry

Respiratory Failure

Science.gov (United States)

Respiratory failure happens when not enough oxygen passes from your lungs into your blood. Your body's organs, ... brain, need oxygen-rich blood to work well. Respiratory failure also can happen if your lungs can' ...

Respiratory system

Science.gov (United States)

Bartlett, R. G., Jr.

1973-01-01

The general anatomy and function of the human respiratory system is summarized. Breathing movements, control of breathing, lung volumes and capacities, mechanical relations, and factors relevant to respiratory support and equipment design are discussed.

CFD model of a spinning pipe gas lens

CSIR Research Space (South Africa)

Snedden, Glen C

2006-07-01

Full Text Available Slides on: Spinning Pipe Gas Lens; Focal Length; Refractive Index; Gas Dynamics; Guess at the gas dynamics; Density Profile; Flow Profile; Rosby Waves; Rayleigh–Taylor Instabilities...

Locomotor-Respiratory Coupling in Wheelchair Racing Athletes: A Pilot Study.

Science.gov (United States)

Perret, Claudio; Wenger, Martin; Leicht, Christof A; Goosey-Tolfrey, Victoria L

2016-01-01

In wheelchair racing, respiratory muscles of the rib cage are concomitantly involved in non-ventilatory functions during wheelchair propulsion. However, the relationship between locomotor-respiratory coupling (LRC: the ratio between push and breathing frequency), respiratory parameters and work efficiency is unknown. Therefore, the aim of the present study was to investigate the LRC in wheelchair racers over different race distances. Eight trained and experienced wheelchair racers completed three time-trials over the distances of 400, 800, and 5000 m on a training roller in randomized order. During the time trials, ventilatory and gas exchange variables as well as push frequency were continuously registered to determine possible LRC strategies. Four different coupling ratios were identified, namely 1:1; 2:1, 3:1 as well as a 1:1/2:1 alternating type, respectively. The 2:1 coupling was the most dominant type. The 1:1/2:1 alternating coupling type was found predominantly during the 400 m time-trial. Longer race distances tended to result in an increased coupling ratio (e.g., from 1:1 toward 2:1), and an increase in coupling ratio toward a more efficient respiration was found over the 5000 m distance. A significant correlation (r = 0.80, p respiratory frequency and the respiratory equivalent for oxygen was found for the 400 m and the 800 m time-trials. These findings suggest that a higher coupling ratio indicates enhanced breathing work efficiency with a concomitant deeper and slower respiration during wheelchair racing. Thus, the selection of an appropriate LRC strategy may help to optimize wheelchair racing performance.

Topological phase transition in the quench dynamics of a one-dimensional Fermi gas with spin–orbit coupling

International Nuclear Information System (INIS)

Wang, Pei; Yi, Wei; Xianlong, Gao

2015-01-01

We study the quench dynamics of a one-dimensional ultracold Fermi gas with synthetic spin-orbit coupling. At equilibrium, the ground state of the system can undergo a topological phase transition and become a topological superfluid with Majorana edge states. As the interaction is quenched near the topological phase boundary, we identify an interesting dynamical phase transition of the quenched state in the long-time limit, characterized by an abrupt change of the pairing gap at a critical quenched interaction strength. We further demonstrate the topological nature of this dynamical phase transition from edge-state analysis of the quenched states. Our findings provide interesting clues for the understanding of topological phase transitions in dynamical processes, and can be useful for the dynamical detection of Majorana edge states in corresponding systems. (paper)

Topological phase transition in the quench dynamics of a one-dimensional Fermi gas with spin-orbit coupling

Science.gov (United States)

Wang, Pei; Yi, Wei; Xianlong, Gao

2015-01-01

We study the quench dynamics of a one-dimensional ultracold Fermi gas with synthetic spin-orbit coupling. At equilibrium, the ground state of the system can undergo a topological phase transition and become a topological superfluid with Majorana edge states. As the interaction is quenched near the topological phase boundary, we identify an interesting dynamical phase transition of the quenched state in the long-time limit, characterized by an abrupt change of the pairing gap at a critical quenched interaction strength. We further demonstrate the topological nature of this dynamical phase transition from edge-state analysis of the quenched states. Our findings provide interesting clues for the understanding of topological phase transitions in dynamical processes, and can be useful for the dynamical detection of Majorana edge states in corresponding systems.

The effect of gas cooking on bronchial hyperresponsiveness and the role of immunoglobulin E

NARCIS (Netherlands)

Kerkhof, M; de Monchy, JGR; Rijken, B; Schouten, JP

1999-01-01

Some studies have shown an association between gas cooking and respiratory symptoms. This study investigated whether gas cooking affects bronchial responsiveness and whether particular subjects are more sensitive to this effect. Multiple linear regression analysis was performed with the

Statistical mechanical model of gas adsorption in porous crystals with dynamic moieties.

Science.gov (United States)

Simon, Cory M; Braun, Efrem; Carraro, Carlo; Smit, Berend

2017-01-17

Some nanoporous, crystalline materials possess dynamic constituents, for example, rotatable moieties. These moieties can undergo a conformation change in response to the adsorption of guest molecules, which qualitatively impacts adsorption behavior. We pose and solve a statistical mechanical model of gas adsorption in a porous crystal whose cages share a common ligand that can adopt two distinct rotational conformations. Guest molecules incentivize the ligands to adopt a different rotational configuration than maintained in the empty host. Our model captures inflections, steps, and hysteresis that can arise in the adsorption isotherm as a signature of the rotating ligands. The insights disclosed by our simple model contribute a more intimate understanding of the response and consequence of rotating ligands integrated into porous materials to harness them for gas storage and separations, chemical sensing, drug delivery, catalysis, and nanoscale devices. Particularly, our model reveals design strategies to exploit these moving constituents and engineer improved adsorbents with intrinsic thermal management for pressure-swing adsorption processes.

Gas dynamic laser having shutter doors

International Nuclear Information System (INIS)

Olinger, J.B. Jr.; Wahl, R.L.

1975-01-01

A gas dynamic laser is shown wherein gases containing constituents necessary to obtain a lasing action are passed through a nozzle array and directed into a lasing cavity and through a diffuser to an exit. An opening is located on each side of said lasing cavity with a shutter box outside of said cavity having a shutter door for opening or closing said opening. A mirror box is located behind each shutter box and contains a mirror. These mirrors are aligned with the openings in the lasing cavity with each door positioned between an opening and a mirror. Another outlet opening is positioned downstream of the first opening which provides an outlet opening for a laser beam. A shutter box is located around this opening and also houses a shutter door for opening and closing said opening. The mirror box which extends behind this shutter box includes opening means for permitting the output beam to pass through an aerodynamic window to atmosphere. Actuating means are provided for rapidly opening and closing said shutter doors. Bearing means including recirculating balls are located on the top and bottom of each shutter door to ride in tracks at an angle to the sealing surface on the laser device. Vacuum means are provided to reduce the pressure in the shutter box and mirror box independently of the pressure in the lasing cavity

Steady-state and dynamic analysis of a jet engine, gas lubricated shaft seal

Science.gov (United States)

Shapiro, W.; Colsher, R.

1974-01-01

Dynamic response of a gas-lubricated, jet-engine main shaft seal was analytically established as a function of collar misalignment and secondary seal friction. Response was obtained by a forward integration-in-time (time-transient) scheme, which traces a time history of seal motions in all its degrees of freedom. Results were summarized in the form of a seal tracking map which indicated regions of acceptable collar misalignments and secondary seal friction. Methodology, results and interpretations are comprehensively described.

Dynamics of gas-phase transient species studied by dissociative photodetachment of molecular anions

OpenAIRE

Lu, Zhou

2007-01-01

Gas-phase transient species, such as the CH₃CO₂ and HOCO free radicals, play important roles in combustion and environment chemistry. In this thesis work, the dynamics of these two radicals were studied by dissociative photodetachment (DPD) of the negative ions, CH₃CO₂-С and HOCO⁻, respectively. The experiments were carried out with a fast-ion-beam photoelectron-photofragment coincidence (PPC) spectrometer. Mass-selected molecular anions in a fast ion beam were intercepted by a linearly polar...

Effects of Gas Rarefaction on Dynamic Characteristics of Micro Spiral-Grooved Thrust Bearing

OpenAIRE

Liu, Ren; Wang, Xiao-Li; Zhang, Xiao-Qing

2012-01-01

The effects of gas-rarefaction on dynamic characteristics of micro spiral-grooved-thrust-bearing are studied. The Reynolds equation is modified by the first order slip model, and the corresponding perturbation equations are then obtained on the basis of the linear small perturbation method. In the converted spiral-curve-coordinates system, the finite-volume-method (FVM) is employed to discrete the surface domain of micro bearing. The results show, compared with the continuum-flow model, that ...

Respiratory Viruses in Febrile Neutropenic Patients with Respiratory Symptoms

Directory of Open Access Journals (Sweden)

Mohsen Meidani

2018-01-01

Full Text Available Background: Respiratory infections are a frequent cause of fever in neutropenic patients, whereas respiratory viral infections are not frequently considered as a diagnosis, which causes high morbidity and mortality in these patients. Materials and Methods: This prospective study was performed on 36 patients with neutropenia who admitted to hospital were eligible for inclusion with fever (single temperature of >38.3°C or a sustained temperature of >38°C for more than 1 h, upper and lower respiratory symptoms. Sampling was performed from the throat of the patient by the sterile swab. All materials were analyzed by quantitative real-time multiplex polymerase chain reaction covering the following viruses; influenza, parainfluenza virus (PIV, rhinovirus (RV, human metapneumovirus, and respiratory syncytial virus (RSV. Results: RV was the most frequently detected virus and then RSV was the most. PIV was not present in any of the tested samples. Furthermore, no substantial differences in the distribution of specific viral species were observed based on age, sex, neutropenia duration, hematological disorder, and respiratory tract symptoms and signs (P > 0.05. Conclusion: Our prospective study supports the hypothesis that respiratory viruses play an important role in the development of neutropenic fever, and thus has the potential to individualize infection treatment and to reduce the extensive use of antibiotics in immunocompromised patients with neutropenia.

Middle East Respiratory Syndrome

Centers for Disease Control (CDC) Podcasts

2014-07-07

This podcast discusses Middle East Respiratory Syndrome, or MERS, a viral respiratory illness caused by Middle East Respiratory Syndrome Coronavirus—MERS-CoV.  Created: 7/7/2014 by National Center for Immunization and Respiratory Diseases (NCIRD).   Date Released: 7/7/2014.

Optimization behavior of brainstem respiratory neurons. A cerebral neural network model.

Science.gov (United States)

Poon, C S

1991-01-01

A recent model of respiratory control suggested that the steady-state respiratory responses to CO2 and exercise may be governed by an optimal control law in the brainstem respiratory neurons. It was not certain, however, whether such complex optimization behavior could be accomplished by a realistic biological neural network. To test this hypothesis, we developed a hybrid computer-neural model in which the dynamics of the lung, brain and other tissue compartments were simulated on a digital computer. Mimicking the "controller" was a human subject who pedalled on a bicycle with varying speed (analog of ventilatory output) with a view to minimize an analog signal of the total cost of breathing (chemical and mechanical) which was computed interactively and displayed on an oscilloscope. In this manner, the visuomotor cortex served as a proxy (homolog) of the brainstem respiratory neurons in the model. Results in 4 subjects showed a linear steady-state ventilatory CO2 response to arterial PCO2 during simulated CO2 inhalation and a nearly isocapnic steady-state response during simulated exercise. Thus, neural optimization is a plausible mechanism for respiratory control during exercise and can be achieved by a neural network with cognitive computational ability without the need for an exercise stimulus.

Fundamental study on repairing technique for cracked or damaged parts of structures by cold gas dynamic spray technique

International Nuclear Information System (INIS)

Ogawa, Kazuhiro; Amao, Satoshi; Ichikawa, Yuji; Shoji, Tetsuo

2008-01-01

This study proposes an innovative technique for repairing of cracked or damaged parts of structures, such as nuclear or thermal power plants, by means of cold gas dynamic spray (CS) technique. In the case of generation of cracks etc. in the structure, the cracks can be repaired by welding. However, the welding spends considerable time on repair, and also needs special skills. The CS technique is known as a new technique not only for coatings but also for thick depositions. It has many advantages, i.e. dense deposition, high deposition rate and low oxidation. Therefore, it has a possibility to apply the CS technique instead of welding to repair the cracks etc. In this study, the cold gas dynamic spray technique as a new repairing technique for some structures is introduced. (author)

Respiratory Manifestations of Hypothyroidism: A Systematic Review.

Science.gov (United States)

Sorensen, Jesper Roed; Winther, Kristian Hillert; Bonnema, Steen Joop; Godballe, Christian; Hegedüs, Laszlo

2016-11-01

Hypothyroidism has been associated with increased pulmonary morbidity and overall mortality. A systematic review was conducted to identify the prevalence and underlying mechanisms of respiratory problems among patients with thyroid insufficiency. PubMed and EMBASE databases were searched for relevant literature from January 1950 through January 2015 with the following study eligibility criteria: English-language publications; adult subclinical or overt hypothyroid patients; intervention, observational, or retrospective studies; and respiratory manifestations. The Preferred Reporting Items for Systematic reviews and Meta-Analyses statement was followed, and Cochrane's risk of bias tool was used. A total of 1699 papers were screened by two independent authors for relevant titles. Of 109 relevant abstracts, 28 papers underwent full-text analyses, of which 22 were included in the review. Possible mechanisms explaining respiratory problems at multiple physiological levels were identified, such as the ventilator control system, diaphragmatic muscle function, pulmonary gas exchange, goiter caused upper airway obstruction, decreased capacity for energy transduction, and reduced glycolytic activity. Obstructive sleep apnea syndrome was found among 30% of newly diagnosed patients with overt hypothyroidism, and demonstrated reversibility following treatment. The evidence for or against a direct effect on pulmonary function was ambiguous. However, each of the above-mentioned areas was only dealt with in a limited number of studies. Therefore, it is not possible to draw any strong conclusions on any of these themes. Moreover, most studies were hampered by considerable risk of bias due for example to small numbers of patients, lack of control groups, randomization and blinding, and differences in body mass index, sex, and age between subjects and controls. Mechanistic data linking hypothyroidism and respiratory function are at best limited. This area of research is therefore

Experimental Combustion Dynamics Behavior of a Multi-Element Lean Direct Injection (LDI) Gas Turbine Combustor

Science.gov (United States)

Acosta, Waldo A.; Chang, Clarence T.

2016-01-01

An experimental investigation of the combustion dynamic characteristics of a research multi-element lean direct injection (LDI) combustor under simulated gas turbine conditions was conducted. The objective was to gain a better understanding of the physical phenomena inside a pressurized flametube combustion chamber under acoustically isolated conditions. A nine-point swirl venturi lean direct injection (SV-LDI) geometry was evaluated at inlet pressures up to 2,413 kPa and non-vitiated air temperatures up to 867 K. The equivalence ratio was varied to obtain adiabatic flame temperatures between 1388 K and 1905 K. Dynamic pressure measurements were taken upstream of the SV-LDI, in the combustion zone and downstream of the exit nozzle. The measurements showed that combustion dynamics were fairly small when the fuel was distributed uniformly and mostly due to fluid dynamics effects. Dynamic pressure fluctuations larger than 40 kPa at low frequencies were measured at 653 K inlet temperature and 1117 kPa inlet pressure when fuel was shifted and the pilot fuel injector equivalence ratio was increased to 0.72.

Human herpesviruses respiratory infections in patients with acute respiratory distress (ARDS).

Science.gov (United States)

Bonizzoli, Manuela; Arvia, Rosaria; di Valvasone, Simona; Liotta, Francesco; Zakrzewska, Krystyna; Azzi, Alberta; Peris, Adriano

2016-08-01

Acute respiratory distress syndrome (ARDS) is today a leading cause of hospitalization in intensive care unit (ICU). ARDS and pneumonia are closely related to critically ill patients; however, the etiologic agent is not always identified. The presence of human herpes simplex virus 1, human cytomegalovirus and Epstein-Barr virus in respiratory samples of critically ill patients is increasingly reported even without canonical immunosuppression. The main aim of this study was to better understand the significance of herpesviruses finding in lower respiratory tract of ARDS patients hospitalized in ICU. The presence of this group of herpesviruses, in addition to the research of influenza viruses and other common respiratory viruses, was investigated in respiratory samples from 54 patients hospitalized in ICU, without a known microbiological causative agent. Moreover, the immunophenotype of each patient was analyzed. Herpesviruses DNA presence in the lower respiratory tract seemed not attributable to an impaired immunophenotype, whereas a significant correlation was observed between herpesviruses positivity and influenza virus infection. A higher ICU mortality was significantly related to the presence of herpesvirus infection in the lower respiratory tract as well as to impaired immunophenotype, as patients with poor outcome showed severe lymphopenia, affecting in particular T (CD3+) cells, since the first days of ICU hospitalization. In conclusion, these results indicate that herpesviruses lower respiratory tract infection, which occurs more frequently following influenza virus infection, can be a negative prognostic marker. An independent risk factor for ICU patients with ARDS is an impaired immunophenotype.

Contrasting dynamics of leaf potential and gas exchange during progressive drought cycles and recovery in Amorpha fruticosa and Robinia pseudoacacia.

Science.gov (United States)

Yan, Weiming; Zheng, Shuxia; Zhong, Yangquanwei; Shangguan, Zhouping

2017-06-30

Leaf gas exchange is closely associated with water relations; however, less attention has been given to this relationship over successive drought events. Dynamic changes in gas exchange and water potential in the seedlings of two woody species, Amorpha fruticosa and Robinia pseudoacacia, were monitored during recurrent drought. The pre-dawn leaf water potential declined in parallel with gas exchange in both species, and sharp declines in gas exchange occurred with decreasing water potential. A significant correlation between pre-dawn water potential and gas exchange was observed in both species and showed a right shift in R. pseudoacacia in the second drought. The results suggested that stomatal closure in early drought was mediated mainly by elevated foliar abscisic acid (ABA) in R. pseudoacacia, while a shift from ABA-regulated to leaf-water-potential-driven stomatal closure was observed in A. fruticosa. After re-watering, the pre-dawn water potential recovered quickly, whereas stomatal conductance did not fully recover from drought in R. pseudoacacia, which affected the ability to tightly control transpiration post-drought. The dynamics of recovery from drought suggest that stomatal behavior post-drought may be restricted mainly by hydraulic factors, but non-hydraulic factors may also be involved in R. pseudoacacia.

Comparison of objective methods to classify the pattern of respiratory sinus arrhythmia during mechanical ventilation and paced spontaneous breathing

International Nuclear Information System (INIS)

Carvalho, N C; Beda, A; Granja-Filho, P; Jandre, F C; Giannella-Neto, A; De Abreu, M G; Spieth, P M

2009-01-01

Respiratory sinus arrhythmia (RSA) is a fluctuation of heart period that occurs during a respiratory cycle. It has been suggested that inspiratory heart period acceleration and expiratory deceleration during spontaneous ventilation (henceforth named positive RSA) improve the efficiency of gas exchange compared to the absence or the inversion of such a pattern (negative RSA). During mechanical ventilation (MV), for which maximizing the efficiency of gas exchange is of critical importance, the pattern of RSA is still the object of debate. In order to gain a better insight into this matter, we compared five different methods of RSA classification using the data of five mechanically ventilated piglets. The comparison was repeated using the data of 15 volunteers undergoing a protocol of paced spontaneous breathing, which is expected to result in a positive RSA pattern. The results showed that the agreement between the employed methods is limited, suggesting that the lack of a consensus about the RSA pattern during MV is, at least in part, of methodological origin. However, independently of the method used, the pattern of RSA within the respiratory cycle was not consistent among the subjects and conditions of MV considered. Also, the outcomes showed that even during paced spontaneous breathing a negative RSA pattern might be present, when a low respiratory frequency is imposed

Respiratory diagnostic possibilities during closed circuit anesthesia.

Science.gov (United States)

Verkaaik, A P; Erdmann, W

1990-01-01

An automatic feed back controlled totally closed circuit system (Physioflex) has been developed for quantitative practice of inhalation anesthesia and ventilation. In the circuit system the gas is moved unidirectionally around by a blower at 70 l/min. In the system four membrane chambers are integrated for ventilation. Besides end-expiratory feed back control of inhalation anesthetics, and inspiratory closed loop control of oxygen, the system offers on-line registration of flow, volume and respiratory pressures as well as a capnogram and oxygen consumption. Alveolar ventilation and static compliance can easily be derived. On-line registration of oxygen consumption has proven to be of value for determination of any impairment of tissue oxygen supply when the oxygen delivery has dropped to critical values. Obstruction of the upper or lower airways are immediately detected and differentiated. Disregulations of metabolism, e.g. in malignant hyperthermia, are seen in a pre-crisis phase (increase of oxygen consumption and of CO2 production), and therapy can be started extremely early and before a disastrous condition has developed. Registration of compliance is only one of the continuously available parameters that guarantee a better and adequate control of lung function (e.g. atalectasis is early detected). The newly developed sophisticated anesthesia device enlarges tremendously the monitoring and respiratory diagnostic possibilities of artificial ventilation, gives new insights in the (patho)physiology and detects disturbances of respiratory parameters and metabolism in an early stage.

Fundamentals of gas particle flow

CERN Document Server

Rudinger, G

1980-01-01

Fundamentals of Gas-Particle Flow is an edited, updated, and expanded version of a number of lectures presented on the "Gas-Solid Suspensions” course organized by the von Karman Institute for Fluid Dynamics. Materials presented in this book are mostly analytical in nature, but some experimental techniques are included. The book focuses on relaxation processes, including the viscous drag of single particles, drag in gas-particles flow, gas-particle heat transfer, equilibrium, and frozen flow. It also discusses the dynamics of single particles, such as particles in an arbitrary flow, in a r

Molecular mechanism of adsorption/desorption hysteresis: dynamics of shale gas in nanopores

Science.gov (United States)

Chen, Jie; Wang, FengChao; Liu, He; Wu, HengAn

2017-01-01

Understanding the adsorption and desorption behavior of methane has received considerable attention since it is one of the crucial aspects of the exploitation of shale gas. Unexpectedly, obvious hysteresis is observed from the ideally reversible physical sorption of methane in some experiments. However, the underlying mechanism still remains an open problem. In this study, Monte Carlo (MC) and molecular dynamics (MD) simulations are carried out to explore the molecular mechanisms of adsorption/desorption hysteresis. First, a detailed analysis about the capillary condensation of methane in micropores is presented. The influence of pore width, surface strength, and temperature on the hysteresis loop is further investigated. It is found that a disappearance of hysteresis occurs above a temperature threshold. Combined with the phase diagram of methane, we explicitly point out that capillary condensation is inapplicable for the hysteresis of shale gas under normal temperature conditions. Second, a new mechanism, variation of pore throat size, is proposed and studied. For methane to pass through the throat, a certain energy is required due to the repulsive interaction. The required energy increases with shrinkage of the throat, such that the originally adsorbed methane cannot escape through the narrowed throat. These trapped methane molecules account for the hysteresis. Furthermore, the hysteresis loop is found to increase with the increasing pressure and decreasing temperature. We suggest that the variation of pore throat size can explain the adsorption/desorption hysteresis of shale gas. Our conclusions and findings are of great significance for guiding the efficient exploitation of shale gas.

Molecular dynamics of Middle East Respiratory Syndrome Coronavirus (MERS CoV) fusion heptad repeat trimers