scholarly journals Extragalactic Magnetism with SOFIA (Legacy Program) - II: A Magnetically Driven Flow in the Starburst Ring of NGC 1097*

2021 ◽  
Vol 923 (2) ◽  
pp. 150
Author(s):  
Enrique Lopez-Rodriguez ◽  
Rainer Beck ◽  
Susan E. Clark ◽  
Annie Hughes ◽  
Alejandro S. Borlaff ◽  
...  
Keyword(s):  
Gas Flow ◽  
Decomposition Analysis ◽  
Radial Component ◽  
Host Galaxy ◽  
Gas Flows ◽  
Disk Galaxies ◽  
Field Orientation ◽  
Gas Streams ◽  
Central Engine ◽  
Nuclear Ring

Abstract Galactic bars are frequent in disk galaxies and they may support the transfer of matter toward the central engine of active nuclei. The barred galaxy NGC 1097 has magnetic forces controlling the gas flow at several kpc scales, which suggest that magnetic fields (B-fields) are dynamically important along the bar and nuclear ring. However, the effect of the B-field on the gas flows in the central kpc scale has not been characterized. Using thermal polarized emission at 89 μm with HAWC+/SOFIA, here, we measure that the polarized flux is spatially located at the contact regions of the outer bar with the starburst ring. The linear polarization decomposition analysis shows that the 89 μm and radio (3.5 and 6.2 cm) polarization traces two different modes, m, of the B-field: a constant B-field orientation and dominated by m = 0 at 89 μm, and a spiral B-field dominated by m = 2 at radio. We show that the B-field at 89 μm is concentrated in the warmest region of a shock driven by the galactic-bar dynamics in the contact regions between the outer bar with the starburst ring. Radio polarization traces a superposition of the spiral B-field outside and within the starburst ring. According to Faraday rotation measures between 3.5 and 6.2 cm, the radial component of the B-field along the contact regions points toward the galaxy's center on both sides. We conclude that gas streams outside and within the starburst ring follow the B-field, which feeds the black hole with matter from the host galaxy.

Co-Current and Countercurrent Migration of Gas Kicks in “Horizontal” Wells

1999 ◽  
Vol 121 (2) ◽  
pp. 96-101 ◽  
Author(s):  
H. Baca ◽  
J. Smith ◽  
A. T. Bourgoyne ◽  
D. E. Nikitopoulos
Keyword(s):  
Test Section ◽  
Gas Flow ◽  
Gas Injection ◽  
Horizontal Wells ◽  
Gas Flows ◽  
Countercurrent Flow ◽  
Drilling Operations ◽  
Operating Window ◽  
Annular Pipes ◽  
Injection Rates

Results from experiments conducted in downward liquid-gas flows in inclined, eccentric annular pipes, with water and air as the working fluids, are presented. The gas was injected in the middle of the test section length. The operating window, in terms of liquid and gas superficial velocities, within which countercurrent gas flow occurs at two low-dip angles, has been determined experimentally. The countercurrent flow observed was in the slug regime, while the co-current one was stratified. Countercurrent flow fraction and void fraction measurements were carried out at various liquid superficial velocities and gas injection rates and correlated to visual observations through a full-scale transparent test section. Our results indicate that countercurrent flow can be easily generated at small downward dip angles, within the practical range of liquid superficial velocity for drilling operations. Such flow is also favored by low gas injection rates.

scholarly journals Accretion and Outflow in Active Galaxies

2009 ◽  
Vol 5 (S267) ◽  
pp. 273-282
Author(s):  
Andrew King
Keyword(s):  
Black Hole ◽  
Large Scale ◽  
Host Galaxy ◽  
Small Scale ◽  
Gas Flows ◽  
Inverse Compton ◽  
The Galaxy ◽  
Black Hole Growth ◽  
Lower Excitation ◽  
Hole Growth

AbstractI review accretion and outflow in active galactic nuclei. Accreti4on appears to occur in a series of very small-scale, chaotic events, whose gas flows have no correlation with the large-scale structure of the galaxy or with each other. The accreting gas has extremely low specific angular momentum and probably represents only a small fraction of the gas involved in a galaxy merger, which may be the underlying driver.Eddington accretion episodes in AGN must be common in order for the supermassive black holes to grow. I show that they produce winds with velocities v ~ 0.1c and ionization parameters implying the presence of resonance lines of helium-like and hydrogen-like iron. The wind creates a strong cooling shock as it interacts with the interstellar medium of the host galaxy, and this cooling region may be observable in an inverse Compton continuum and lower-excitation emission lines associated with lower velocities. The shell of matter swept up by the shocked wind stalls unless the black hole mass has reached the value Mσ implied by the M–σ relation. Once this mass is reached, further black hole growth is prevented. If the shocked gas did not cool as asserted above, the resulting (“energy-driven”) outflow would imply a far smaller SMBH mass than actually observed. Minor accretion events with small gas fractions can produce galaxy-wide outflows, including fossil outflows in galaxies where there is little current AGN activity.

scholarly journals Linking the central engine to the jet properties in radio loud AGN

2014 ◽  
Vol 10 (S313) ◽  
pp. 329-330
Author(s):  
A. Olguín-Iglesias ◽  
J. León-Tavares ◽  
V. Chavushyan ◽  
E. Valtaoja ◽  
C. Añorve ◽  
...  
Keyword(s):  
Black Hole ◽  
Host Galaxy ◽  
Base Line ◽  
Black Hole Mass ◽  
Host Galaxies ◽  
Optical Telescope ◽  
Central Engine ◽  
Early Results ◽  
Relativistic Jet ◽  
Line Array

AbstractWe explore the connection between the black hole mass and its relativistic jet for a sample of radio-loud AGN (z < 1), in which the relativistic jet parameters are well estimated by means of long term monitoring with the 14m Metsähovi millimeter wave telescope and the Very Long Base-line Array (VLBA). NIR host galaxy images taken with the NOTCam on the Nordic Optical Telescope (NOT) and retrieved from the 2MASS all-sky survey allowed us to perform a detailed surface brightness decomposition of the host galaxies in our sample and to estimate reliable black hole masses via their bulge luminosities. We present early results on the correlations between black hole mass and the relativistic jet parameters. Our preliminary results suggest that the more massive the black hole is, the faster and the more luminous jet it produces.

scholarly journals Potential of using inert gas flows for controlling the quality of as-grown silicon single crystal

2020 ◽  
Vol 6 (1) ◽  
pp. 1-7
Author(s):  
Tatyana V. Kritskaya ◽  
Vladimir N. Zhuravlev ◽  
Vladimir S. Berdnikov
Keyword(s):  
Single Crystal ◽  
Carbon Content ◽  
Single Crystals ◽  
Gas Flow ◽  
Thermal Stresses ◽  
Crystal Surface ◽  
Gas Flows ◽  
Reaction Products ◽  
Crystal Silicon ◽  
Argon Gas

We have improved the well-known Czochralski single crystal silicon growth method by using two argon gas flows. One flow is the main one (15–20 nl/min) and is directed from top to bottom along the growing single crystal. This flow entrains reaction products of melt and quartz crucible (mainly SiO), removes them from the growth chamber through a port in the bottom of the chamber and provides for the growth of dislocation-free single crystals from large weight charge. Similar processes are well known and have been generally used since the 1970s world over. The second additional gas flow (1.5–2 nl/min) is directed at a 45 arc deg angle to the melt surface in the form of jets emitted from circularly arranged nozzles. This second gas flow initiates the formation of a turbulent melt flow region which separates the crystallization front from oxygen-rich convective flows and accelerates carbon evaporation from the melt. It has been confirmed that oxygen evaporated from the melt (in the form of SiO) acts as transport agent for nonvolatile carbon. Commercial process implementation has shown that carbon content in as-grown single crystals can be reduced to below the carbon content in the charge. Single crystals grown with two argon gas flows have also proven to have highly macro- and micro-homogeneous oxygen distributions, with much greater lengths of single crystal portions in which the oxygen concentration is constant and below the preset limit. Carbon contents of 5–10 times lower than carbon content in the charge can be achieved with low argon gas consumption per one growth process (15–20 nl/min vs 50–80 nl/min for conventional processes). The use of an additional argon gas flow with a 10 times lower flowrate than that of the main flow does not distort the pattern of main (axial) flow circumvention around single crystal surface, does not hamper the “dislocation-free growth” of crystals and does not increase the density of microdefects. This suggests that the new method does not change temperature gradients and does not produce thermal shocks that may generate thermal stresses in single crystals.

scholarly journals Transformation of a mathematical model of gas flow distribution to solve the problems of gas supply system development

2020 ◽  
Vol 219 ◽  
pp. 02001
Author(s):  
Nikolay Ilkevich ◽  
Tatyana Dzyubina ◽  
Zhanna Kalinina
Keyword(s):  
Mathematical Model ◽  
Gas Flow ◽  
System Development ◽  
Flow Distribution ◽  
Supply System ◽  
Economic Environment ◽  
Gas Flows ◽  
Supply Systems ◽  
New Criteria ◽  
Gas Supply

This paper proposes taking into account new properties of gas supply systems in a mathematical model of flow distribution in comparison with the traditional formulation. The approach suggests introducing an arc coefficient, which allows for changes in the magnitude of gas flow passing along the arc, a vector of an increase in the arc throughput, and lower constraints on the gas flow along the arc. We also propose considering a new economic environment, namely, new criteria for optimizing the flow distribution and setting fictitious gas prices for consumers. These criteria enable us to take account of the priority gas supply to a definite group of consumers. As an example, the calculation of gas flows for the aggregated Unified Gas Supply System (UGSS) for 2030 is considered. This calculation takes into account the arc coefficients and the increase in the throughput of arcs.

scholarly journals Cost-effectiveness of Basal Flow Sevoflurane Anaesthesia Using the Komesaroff Vaporizer inside the Circle System

2005 ◽  
Vol 33 (5) ◽  
pp. 609-615 ◽  
Author(s):  
S. P. Nandalan ◽  
R. J. Eltringham ◽  
Q. W. Fan
Keyword(s):  
Gas Flow ◽  
Low Flow ◽  
Gas Flows ◽  
Physical Status ◽  
Mechanically Ventilated ◽  
Sevoflurane Anaesthesia ◽  
Inspiratory Limb ◽  
Low Flow Anaesthesia ◽  
Induction Of Anaesthesia ◽  
Basal Flow

After ethics committee approval, 51 consenting ASA physical status 1 or 2 adult patients were given basal flow sevoflurane anaesthesia using fresh gas flows of 150 to 300 ml.min-1 oxygen. A Komesaroff vaporizer was placed on the inspiratory limb of the circle system. Basal flows were introduced immediately following intravenous induction of anaesthesia. The vaporizer was set to deliver the maximum concentration until the inspired sevoflurane concentration (FSI) reached 3%. The dial was then adjusted to maintain the FSI at 3%. After every 60 minutes, the circuit was washed out with 100% oxygen at a flow rate of 10 l.min-1 for one minute. The FSI reached 3% after an average of 8.5 (3.8) [mean (SD)] minutes. The trends in FSI and the expired sevoflurane concentrations were significantly different (P<0.05) between the mechanically ventilated patients (n=21) and the spontaneously ventilating patients (n=30) and demonstrated a more gradual build-up in the former group. The consumption of sevoflurane was found to be 9.2 (2.8) ml.h-1. This represented a 52.5% cost saving over the clinical application of the Mapleson's ideal fresh gas flow sequence for low-flow anaesthesia.

Highly optimized CO2 capture by inexpensive nanoporous covalent organic polymers and their amine composites

2015 ◽  
Vol 183 ◽  
pp. 401-412 ◽  
Author(s):  
Hasmukh A. Patel ◽  
Cafer T. Yavuz
Keyword(s):  
Flue Gas ◽  
Gas Flow ◽  
Low Cost ◽  
High Specific Surface Area ◽  
Organic Polymers ◽  
Mixed Gas ◽  
Gas Streams ◽  
Promising Application ◽  
Adsorption Of Co ◽  
Adsorption Desorption

Carbon dioxide (CO2) storage and utilization requires effective capture strategies that limit energy penalties. Polyethylenimine (PEI)-impregnated covalent organic polymers (COPs) with a high CO2 adsorption capacity are successfully prepared in this study. A low cost COP with a high specific surface area is suitable for PEI loading to achieve high CO2 adsorption, and the optimal PEI loading is 36 wt%. Though the adsorbed amount of CO2 on amine impregnated COPs slightly decreased with increasing adsorption temperature, CO2/N2 selectivity is significantly improved at higher temperatures. The adsorption of CO2 on the sorbent is very fast, and a sorption equilibrium (10% wt) was achieved within 5 min at 313 K under the flow of simulated flue gas streams. The CO2 capture efficiency of this sorbent is not affected under repetitive adsorption–desorption cycles. The highest CO2 capture capacity of 75 mg g−1 at 0.15 bar is achieved under dry CO2 capture however it is enhanced to 100 mg g−1 in the mixed gas flow containing humid 15% CO2. Sorbents were found to be thermally stable up to at least 200 °C. TGA and FTIR studies confirmed the loading of PEIs on COPs. This sorbent with high and fast CO2 sorption exhibits a very promising application in direct CO2 capture from flue gas.

DSMC Simulation of Rarefied Gas Flow Over a Wall Mounted Cube

2019 ◽  
Author(s):  
Deepak Nabapure ◽  
Ram Chandra Murthy
Keyword(s):  
Gas Flow ◽  
Rarefied Gas ◽  
Flow Behavior ◽  
Direct Simulation Monte Carlo ◽  
Temperature Fields ◽  
Gas Flows ◽  
Rarefied Gas Flows ◽  
Dsmc Simulation ◽  
Recirculation Length ◽  
Velocity Pressure

Abstract The present study investigates the flow behavior of the rarefied gas over a wall-mounted cube. The problem is studied for different cube heights (h) of 9mm and 18mm in the slip and transition regimes. The Direct Simulation Monte Carlo (DSMC) method is employed to evaluate the properties such as velocity, pressure and temperature fields. The Reynolds number (Re) ranges from 403 to 807, and the Knudsen number (Kn) is in the range from 0.05 to 0.103. A typical shock wave is formed in front of the cube. The recirculation length of the vortices normalized with respect to the respective cube heights for Kn = 0.05 and Kn = 0.103 are about 1.11 and 1.95 respectively. Similarly, the center of the vortices is located at about 3.33 and 6.11 times the respective cube heights upstream, for Kn = 0.05 and Kn = 0.103. The local temperature and pressure variations observed upstream of the cube are two orders higher in magnitude and are primarily attributed to strong compressibility effects. The present study paves the way for benchmarking, and forms a basis for understanding the rarefied gas flows over complex geometries.

scholarly journals A survey of the choice of general anaesthetic agents in Australia and New Zealand

2019 ◽  
Vol 47 (3) ◽  
pp. 235-241 ◽  
Author(s):  
Forbes McGain ◽  
Jason R Bishop ◽  
Laura M Elliot-Jones ◽  
David A Story ◽  
Georgina LL Imberger
Keyword(s):  
Nitrous Oxide ◽  
New Zealand ◽  
Gas Flow ◽  
General Anaesthetic ◽  
Gas Flows ◽  
Environmental Costs ◽  
Flow Rates ◽  
Intravenous Anaesthesia ◽  
Anaesthetic Agents ◽  
End Tidal

Strategies to reduce the adverse environmental costs of anaesthesia include choice of agent and fresh gas flows. The current preferences of Australian and New Zealand anaesthetists are unknown. We conducted a survey of Australian and New Zealand anaesthetists to determine the use of volatiles, nitrous oxide and intravenous anaesthesia, lowest fresh gas flow rates, automated end-tidal volatile control, and the rationales for these choices. The survey was answered by 359/1000 (36%), although not all questions and multiple responses within single questions were answered by all respondents. Sevoflurane was preferred by 246/342 (72%, 95% confidence interval (CI) 67%–77%), followed by propofol, 54/340 (16%, 95% CI 12%–20%), desflurane 39/339 (12%, 95% CI 8%–16%) and isoflurane 3/338(1%, 95% CI 0–3%). When asked about all anaesthetics, low-risk clinical profile was the most common reason given for using sevoflurane (129/301 (43%, 95% CI 37%–49%)), reduced postoperative nausea for propofol (297/318 (93%, 95% CI 90%–96%)) and faster induction/awakening times for desflurane (46/313 (79%, 95% CI 74%–83%)). Two-thirds (226/340 (66%, 95% CI 61%–71%)) of respondents used nitrous oxide in 0–20% of general anaesthetics. Low fresh gas flow rates for sevoflurane were used by 310/333 (93%, 95% CI 90%–95%) and for 262/268 (98%, 95% CI 95%–99%) for desflurane. Automated end-tidal control was used by 196/333 (59%, 95% CI 53%–64%). The majority of respondents (>70%) preferred sevoflurane at low flows. These data allow anaesthetists to consider further whether changes are required to the choices of anaesthetic agents for environmental, financial, or any other reasons.

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