Outflow Rate Research Articles

Ionised gas kinematics in MaNGA AGN

Context.Feedback from active galactic nuclei (AGNs) in general seems to play an important role in the evolution of galaxies, although the impact of AGN winds on their host galaxies is still unknown in the absence of a detailed analysis.Aims.We aim to analyse the kinematics of a sample of 170 AGN host galaxies as compared to those of a matched control sample of non-active galaxies from the MaNGA survey in order to characterise and estimate the extents of the narrow-line region (NLR) and of the kinematically disturbed region (KDR) by the AGN.Methods.We defined the observed NLR radius (rNLR, o) as the farthest distance from the nucleus within which both [O III]/Hβand [N II]/Hαratios fall in the AGN region of the BPT diagram, and the Hαequivalent width was required to be larger than 3.0 Å. The extent of the KDR (rKDR, o) is defined as the distance from the nucleus within which the AGN host galaxies show a more disturbed gas kinematics than the control galaxies.Results.The AGN [O III]λ5007 luminosity ranges from 1039to 1041erg s−1, and the kinematics derived from the [O III] line profiles reveal that, on average, the most luminous AGNs (L[O III] > 3.8 × 1040erg s−1) possess higher residual differences between the gaseous and stellar velocities and velocitie dispersions than their control galaxies in all the radial bins. Spatially resolved NLRs and KDRs were found in 55 and 46 AGN host galaxies, with corrected radii 0.2 < rKDR, c < 2.3 kpc and 0.4 < rNLR, c < 10.1 kpc and a relation between the two given by logrKDR, c = (0.53 ± 0.12) logrNLR, c + (1.07 ± 0.22), respectively. On average, the extension of the KDR corresponds to about 30% of that of the NLR. Assuming that the KDR is due to an AGN outflow, we have estimated ionised gas mass outflow rates that range between 10−5and ∼1M⊙yr−1, and kinetic powers that range from 1034to 1040erg s−1.Conclusions.Comparing the power of the AGN ionised outflows with the AGN luminosities, they are always below the 0.05LAGNmodel threshold for having an important feedback effect on their respective host galaxies. The mass outflow rates (and power) of our AGN sample correlate with their luminosities, populating the lowest AGN luminosity range of the correlations previously found for more powerful sources.

Structure of the super-Eddington outflow and its impact on the cosmological scale

Abstract It is one of the biggest issues in black hole (BH) astrophysics how to evaluate BH feedback to its environments precisely. Aiming at studying the unique gas dynamics of super-Eddington flow around supermassive black hole (SMBH) seeds at high redshift, we carried out axisymmetric two-dimensional radiation hydrodynamic simulations using a nested simulation-box method. Here we divide the simulation box into an inner zone at (2–3 × 103)rSch (with rSch being the Schwarzschild radius) and an outer zone at (2 × 103–3 × 106)rSch, with smooth connection of the physical quantities, such as gas density, velocity, and radiation energy. We start the calculation by injecting mass through the outer boundary of the inner zone at a constant rate of $\dot{M}_{\rm {inj}}=10^3L_{\rm {Edd}}/c^2$, where LEdd is the Eddington luminosity and c is the speed of light. A powerful outflow is generated in the innermost region and it propagates from the inner zone to the outer zone. The outflows are characterized by a velocity of 0.02c (0.7c) and density of 10−17 (10−19) g cm−3 for near the edge-on (face-on) direction. The outflow is gradually accelerated as it travels by accepting radiation-pressure force. The final mass outflow rate at the outermost boundary is $\dot{M}_{\rm {out}}\sim 0.3 \times \dot{M}_{\rm {inj}}$. By extrapolating the outflow structure to a further larger scale, we find that the momentum and energy fluxes at r ∼ 0.1 pc are ∼10–100 LEdd/c and ∼0.1–10 LEdd, respectively. Moreover, we find that the impacts are highly anisotropic, in the sense that larger impacts occur towards the face-on direction than in the edge-on direction. These results indicate that the BH feedback will work more efficiently on the interstellar medium than assumed in the cosmological simulations.

Functionalization of halloysite nanotubes via grafting of polyhedral oligomeric silsesquioxane (POSS) nanoparticles for paclitaxel drug delivery

To get high loading capacity and sustained release behavior of paclitaxel (PTX) anticancer drug, halloysite (Hal) nanotubes were functionalized with octa-aminopropyl polyhedral oligomeric silsesquioxane hydrochloride salt nanoparticles (OAPOSS NPs) as novel drug delivery system. The novel nanocarrier, OAPOSS-g-Hal, was characterized using different methods. The in-vitro release experiments showed that PTX outflow rate from OAPOSS-g-Hal at pH 5.2 was higher than pH 7.4. The release kinetics of PTX were studied using Higuchi and Korsmeyer-Peppas models. Moreover, the cytotoxicity effect of the samples against cancer cells was studied using thiazolyl blue tetrazolium bromide assay (MTT). All the above results showed that OAPOSS-g-Hal had a great potential to be a novel drug delivery system.

The Impact of Vapor Blockage on the Outflow Rate of Screen Channel Liquid Acquisition Devices.

The outflow rate of screen channel liquid acquisition devices (LADs) is a key indicator of the liquid acquisition capacity, but would be decreased when a portion of its screen is blocked by the vapor. So far, the quantitative research about the consequent loss of outflow rate seems not enough, though it is important and inevitable. In this paper, a modified model by introducing an “available rate” to describe the blocked degree is established to analyze and compare the cases with and without vapor blockage. We found that the loss of outflow rate is mainly decided by the total area of the blocked screen, while the distribution of blockage position barely has any effects. Besides, a “characteristic curve” is proposed to describe the robustness of LAD against blockage (i.e., loss rate of outflow velocity versus total area of the blocked screen). Higher driving pressure, coarser mesh of screen, and higher ratio of length to height of the channel would bring about greater robustness.

Measurements of basal d-glucose transport through GLUT1 across the intact plasma membrane of isolated segments from single fast- and slow-twitch skeletal muscle fibres ofrat.

AimTo develop a method for direct measurement of the fluorescent d‐glucose analogue 2‐NBDG transport across the plasma membrane of single skeletal muscle fibres and derive the theoretical framework for determining the kinetic parameters for d‐glucose transport under basal conditions.MethodsA novel method is described for measuring free 2‐NBDG transport across plasma membrane of single rat muscle fibres at rest. The 2‐NBDG uptake was >90% suppressed by 100 µM cytochalasin B in both fast‐twitch and slow‐twitch fibres, indicating that the 2‐NBDG transport is GLUT‐mediated. Fibres were identified as fast‐twitch or slow‐twitch based on the differential sensitivity of their contractile apparatus to Sr2+.ResultsThe time course of 2‐NBDG uptake in the presence of 50 µM 2‐NBDG follows a one‐phase exponential plateau curve and is faster in fast‐twitch (rate constant 0.053 ± 0.0024 s‐1) than in slow‐twitch fibres (rate constant 0.031 ± 0.0021 s‐1). The rate constants were markedly reduced in the presence of 20 mM d‐glucose to 0.0082 ± 0.0004 s‐1 and 0.0056 ± 0.0002 s‐1 in fast‐twitch and slow‐twitch fibres respectively. 2‐NBDG transport was asymmetric, consistent with GLUT1 being the major functional GLUT isoform transporting 2‐NBDG in muscle fibres at rest. The parameters describing the transport kinetics for both 2‐NBDG and d‐glucose (dissociation constants, Michaelis–Menten constants, maximal rates of uptake and outflow) were calculated from the measurements made with 2‐NBDG.ConclusionFree 2‐NBDG and d‐glucose transport across the plasma membrane of single rat muscle fibres at rest is fast, conclusively showing that the rate‐limiting step in d‐glucose uptake in skeletal muscle is not necessarily the GLUT‐mediated transport of d‐glucose.

Pressure performance for a thin-walled ring and turbulent-jet orifice modeled elastic squeeze film damper

This paper explores an analytical model for Elastic Ring Squeeze Film Damper (ERSFD) with thin-walled ring and turbulent-jet orifices, and uncovers its Oil Film Pressure Performance (OFPP). Firstly, the ring deformation is addressed by using the Fourier series expansion approach and the orifice outflow rate is characterized with the Prandtl boundary layer theory. Secondly, applying finite difference scheme, the influence of elastic ring flexibility, orifice diameter, and attitude angle on the OFPP is analyzed. Finally, Outer chamber pressure was measured experimentally at different rotor speeds. The results indicate that the outer chamber pressure coats an individual load-carrying region and spreads symmetrically pertaining to the attitude angle. Its amplitude drops as the elastic ring flexibility decreases but boosts with the reduction of the orifice diameter. For inner chamber pressure, the orifice diameter effects a similar trend to the outer cavity, but exhibits more stable distribution regarding the attitude angle. Minimizing the elastic ring flexibility causes an increase in amplitude. The model is validated by the test results giving that the outer chamber pressure shifts synchronously and periodically with the variation of the attitude angle, while the pressure amplitude increases slightly at higher rotor speeds.

The CGM–GRB Study. II. Outflow–Galaxy Connection at z ∼ 2–6

Abstract We use a sample of 27 gamma-ray bursts (GRBs) at redshift z = 2–6 to probe the outflows in their respective host galaxies (log(M */M ⊙) ∼ 9–11) and search for possible relations between the outflow properties and those of the host galaxies, such as M *, the star formation rate (SFR), and the specific SFR (sSFR). First, we consider three outflow properties: outflow column density (N out), maximum outflow velocity (V max), and normalized maximum velocity (V norm = V max/V circ,halo, where V circ,halo is the halo circular velocity). We observe clear trends of N out and V max with increasing SFR in high-ion-traced outflows, with a stronger (>3σ) V max–SFR correlation. We find that the estimated mass outflow rate and momentum flux of the high-ion outflows scale with SFR and can be supported by the momentum imparted by star formation (supernovae and stellar winds). The kinematic correlations of high-ion-traced outflows with SFR are similar to those observed for star-forming galaxies at low redshifts. The correlations with SFR are weaker in low-ion outflows. This, along with the lower detection fraction in low-ion outflows, indicates that the outflow is primarily high-ion dominated. We also observe a strong (>3σ) trend of normalized velocity (V norm) decreasing with halo mass and increasing with sSFR, suggesting that outflows from low-mass halos and high-sSFR galaxies are most likely to escape and enrich the outer circumgalactic medium (CGM) and intergalactic medium with metals. By comparing the CGM–GRB stacks with those of starbursts at z ∼ 2 and z ∼ 0.1, we find that over a broad redshift range, the outflow strength strongly depends on the main-sequence offset at the respective redshifts, rather than simply the SFR.

Do disability benefits hinder work resumption after recovery?

While a large share of Disability Insurance recipients in OECD countries are expected to recover, outflow rates from temporary disability schemes are typically negligible. We estimate the disincentive effects of disability benefits on the response to a (mental) health improvement using administrative data on all Dutch disability benefit applicants. We compare those below the DI eligibility threshold with those above and find that disincentives significantly reduce work resumption after health improves. Approximately half of the response to recovery is offset by benefits. Estimates from a structural labor supply model suggest that disincentives are substantially larger when the worker’s earnings capacity is fully restored.

Cool outflows in MaNGA: a systematic study and comparison to the warm phase

ABSTRACT This paper investigates the neutral gas phase of galactic winds via the Na i Dλλ5890, 5895Å feature within z ∼ 0.04 MaNGA galaxies and directly compares their incidence and strength to the ionized winds detected within the same parent sample. We find evidence for neutral outflows in 127 galaxies (∼5 per cent of the analysed line-emitting sample). ${\rm Na\, \small {\rm I}\ D}$ winds are preferentially seen in galaxies with dustier central regions and both wind phases are more often found in systems with elevated star formation rate (SFR) surface densities, especially when there has been a recent upturn in the star formation activity according to the $\rm SFR_{5 \, Myr}/SFR_{800 \, Myr}$ parameter. We find the ionized outflow kinematics to be in line with what we measure in the neutral phase. This demonstrates that, despite their small contributions to the total outflow mass budget, there is value to collecting empirical measurements of the ionized wind phase to provide information on bulk motion in the outflow. Depending on dust corrections applied to the ionized gas diagnostics, the neutral phase has ∼1.2−1.8 dex higher mass outflow rates ($\dot{M}_{\rm out}$), on average, compared to the ionized phase. We quantify scaling relations between $\dot{M}_{\rm out}$ and the strengths of the physical wind drivers (SFR, LAGN). Using a radial–azimuthal stacking method, and by considering inclination dependencies, we find results consistent with biconical outflows orthogonal to the disc plane. Our work complements other multiphase outflow studies in the literature that consider smaller samples, more extreme objects, or proceed via stacking of larger samples.

The launching of cosmic ray-driven outflows

ABSTRACT Cosmic rays (CRs) are thought to be an important feedback mechanism in star-forming galaxies. They can provide an important source of pressure support and possibly drive outflows. We perform multidimensional CR magnetohydrodynamic simulations including transport by streaming and diffusion to investigate wind launching from an initially hydrostatic atmosphere by CRs. We estimate a characteristic Eddington limit on the CR flux for which the CR force exceeds gravity and compare it to simulated systems. Scaling our results to conditions in star-forming galaxies, we find that CRs are likely to contribute to driving outflows for a broad range of star formation environments. We quantify the momentum and energy transfer between CRs and gas, along with the associated mass outflow rates under different assumptions about the relative importance of streaming and diffusion for transport. In simulations with streaming, we observe the growth and saturation of the CR acoustic instability, but the CRs and gas remain well coupled, with CR momentum transferred efficiently to the gas even when this instability is present. Higher CR fluxes transfer more energy to the gas and drive stronger outflows. When streaming is present, most of the transferred energy takes the form of Alfvén wave heating of the gas, raising its pressure and internal energy, with a lower fractional contribution to the kinetic energy of the outflow. We also consider runs with radiative cooling, which modifies gas temperature and pressure profiles but does not seem to have a large impact on the mass outflow for super-Eddington CR fluxes.

BASS XXXI: Outflow scaling relations in low redshift X-ray AGN host galaxies with MUSE

ABSTRACT Ionized gas kinematics provide crucial evidence of the impact that active galactic nuclei (AGNs) have in regulating star formation in their host galaxies. Although the presence of outflows in AGN host galaxies has been firmly established, the calculation of outflow properties such as mass outflow rates and kinetic energy remains challenging. We present the [O iii]λ5007 ionized gas outflow properties of 22 z<0.1 X-ray AGN, derived from the BAT AGN Spectroscopic Survey using MUSE/VLT. With an average spatial resolution of 1 arcsec (0.1–1.2 kpc), the observations resolve the ionized gas clouds down to sub-kiloparsec scales. Resolved maps show that the [O iii] velocity dispersion is, on average, higher in regions ionized by the AGN, compared to star formation. We calculate the instantaneous outflow rates in individual MUSE spaxels by constructing resolved mass outflow rate maps, incorporating variable outflow density and velocity. We compare the instantaneous values with time-averaged outflow rates by placing mock fibres and slits on the MUSE field-of-view, a method often used in the literature. The instantaneous outflow rates (0.2–275 M⊙ yr−1) tend to be two orders of magnitude higher than the time-averaged outflow rates (0.001–40 M⊙ yr−1). The outflow rates correlate with the AGN bolometric luminosity (Lbol ∼ 1042.71–1045.62 erg s−1) but we find no correlations with black hole mass (106.1–108.9 M⊙), Eddington ratio (0.002–1.1), and radio luminosity (1021–1026 W Hz−1). We find the median coupling between the kinetic energy and Lbol to be 1 per cent, consistent with the theoretical predictions for an AGN-driven outflow.

Дослідження впливу вертикальних коливань штанги обприскувача на рівномірність обприскування

At the present stage of development of technologies for growing agricultural crops, the technological operation of spraying remains relevant. This method performs chemical protection of plants and their nutrition as well. Bar sprayers are still the main machines. The final result - crop yield depends on the technical efficiency of spraying. Other factors that need to be maintained in chemical protection include compliance with the rate of outflow per unit target area. Based on this, the factors that affect the technical efficiency of spraying were analyzed. Among them, the influence of the position of the rod on compliance with the rate of outflow of the working solution per unit area is highlighted. To realize the purpose of the work, which is to find the allowable amplitude of oscillation of the rod, an analysis of a number of literature sources was done. From there, the link between the height of the rod above the treatment object and the pour rate is established. Based on the obtained criteria, a model is constructed, which connects the height of the bar installation above the cultivated area and the quantitative flow through the spraying device per unit of processing area. The implementation of the model is a numerical experiment, which allowed to obtain the percentage numerical values of the uneven coverage of the processing area. Such results were obtained for models that simulate spraying of areas with continuous application of the working solution and treatment of row crops. According to calculations, the following results were obtained. When continuous application of the working solution and the use of sprays with a spray angle , the minimum installation height of the bar above the workpiece must be ≥0,15 m; for sprayers with – height ≥0,15 m. When processing row crops with rows of 0,45 m and the width of the effective area of spraying 0,15 m, we will have: for sprays the minimum optimum height of installation of a bar is 0,6 m – amplitude ±0,045 m; for sprayers with – 0,43 m ±0,04 m. When processing row crops with rows of 0,7 m and an effective spraying area of 0,3 m, we will have: for sprays the minimum optimum height of installation of a bar is 0,6 m – amplitude ± 0,08 m; for sprayers with – 0,6 m.

Computational Study of Anastomosis Angle of Arteriovenous Fistula for Hemodialysis

Arteriovenous fistula (AVF) is the endorsed method of vascular access for hemodialysis in end-stage renal disease (ESRD). However, more than 60% of AVF fail to mature for hemodialysis. Intimal hyperplasia leads to stenosis is the primary cause of fistula failure. Wall shear stress (WSS) is one of the important parameters that enact a crucial role in building of intimal hyperplasia. The prime purpose of this research work is to investigate the effect of anastomosis angle on WSS, pressure drop, venous outflow rate and identify the optimal angle of anastomosis of AVF, so that it helps to standardize the surgical technique. In this research work, three-dimensional idealized geometries of end-to-side type AVF for the four different angles of anastomosis are created. Numerical simulation performed using incompressible, Newtonian blood to calculate the WSS, blood flow rate at the distal end of the vein and pressure drop across the anastomosis for the three arterial inflow 350, 500 and 900 ml/min. For all three arterial inflow, the WSS is high at 75° compared to other angles and it is less at 60°. The WSS at 45° and 90° are moderate. The venous outflow is increasing with the increase in arterial inflow condition for all anastomosis angles except for 45°. The outflow rate at distal venous end is highest, 344.85 ml/min at 45° for 500 ml/min arterial inflow. Pressure drop high at 45° and lowest at 90°. The intensity of disturbed flow and recirculation zone was observed at the area of anastomosis and it is high at 75°. From the results and observations, it can be concluded that 45° angle is the best choice for the anastomosis of AVF. This finding will standardize the surgical technique and subsequently, it will help to mature the AVF early and for a long time.

Nutritive value of mixed napier grass (Pennisetum purpureum)- Leucaena (Leucaena leucocephala) silage for ruminants

The objectives of the study were to determine the chemical composition, ruminal degradability, and apparent digestibility of mixed Napier (Pennisetum purpureum) (PP) -Leucaena (Leucaena leucocephala) (LL) silages. Freshly cut Napier and Leucaena were harvested and mixed at 70:30; 50:50; 30:70 ensiled for six weeks. The chemical composition of the fresh forages and the silages were determined using the AOAC (1990) procedures. Dry matter (DM) and crude protein (CP) ruminal degradability were determined by nylon bag technique using three rumen cannulated Bonsmara steers for periods of 0, 6, 12, 24, 48, 72, 96 and 120 hours. DM and CP ruminal degradability kinetics were described by fitting the data on the model P= a+b (1-e−ct) using the neway computer program where a is the rapidly degradable fraction, b is the slowly degradable fraction and c is the outflow rate. Hay supplemented with 25% mixed PP: LL silages was fed to three castrated male Pedi sheep to evaluate apparent digestibility coefficient and N retention. The fresh cut PP had more CP, Fat, and ash, with less OM. Leucaena was richer in most nutrients than Napier. The study indicated the 50:50 silage was the optimal mix to maximize the overall nutritive value. The DM and CP disappearance constants a, b and c were similar for all silages. PP: LL mixing ratio did not affect the DM and CP degradability kinetics of the silages. There was no effect on total dietary intake, apparent digestibility and N retention.

Modeling temporal changes in salinity and fluoride concentration of Lake Ulungur in Xinjiang, China

为研究乌伦古湖矿化度和氟化物浓度与各水量因子间的定量关系，本研究以水量平衡和物质平衡为基础，把影响湖水水质的原因分为降雨、蒸发、河流补给、地下水补给以及地下水流出5个水量因子，定量分析湖水矿化度和氟化物浓度与各水量因子之间的关系，并且预测了湖水矿化度和氟化物浓度的动态变化.结果表明，地下水输出流量决定了湖水中矿化度和氟化物浓度，地下水输出流量越大，湖水中的矿化度和氟化物浓度越小.2010年至今乌伦古湖水位的升高导致了地下水输出流量增大，乌伦古湖内的矿化度和氟化物浓度均呈缓慢下降趋势，模型预测新的稳态下湖水中矿化度为1.68 g/L，氟化物浓度为1.70 mg/L，在地下水输出流量不变的情况下达到新的稳态所需时间大约为50 a.;In order to evaluate the quantitative relationship between salinity and fluoride concentration and their control factors in Lake Ulungur in Xinjiang, China, this study develops a model for predicting stable state and dynamic water salinity based on water mass balance and solute balance. The input parameters are rainfall, evaporation, river recharge, groundwater recharge, groundwater outflow, and their associated salinity. The concentration of fluoride can also be modeled following the same approach, which provides another constraint on input parameters. The results show that the groundwater outflow significantly affects the salinity and fluoride concentration in lake water, with increasing outflow leading to lower salinity and fluoride concentration in Lake Ulungur. The rise of lake water level leads to increased outflow of groundwater in Lake Ulungur between 2010 and 2020, and the salinity and fluoride concentration in lake water decreased slowly. Our model predicts that the salinity of the Lake Ulungur in the new stable state is 1.68 g/L, and the concentration of fluoride is 1.70 mg/L, but it will take roughly 50 years to reach the new stable state given that the outflow rate remains constant.

Driving Galactic Outflows with Magnetic Fields at Low and High Redshift

Abstract Although galactic outflows play a key role in our understanding of the evolution of galaxies, the exact mechanism by which galactic outflows are driven is still far from being understood and, therefore, our understanding of associated feedback mechanisms that control the evolution of galaxies is still plagued by many enigmas. In this work, we present a simple toy model that can provide insight on how non-axisymmetric instabilities in galaxies (bars, spiral arms, warps) can lead to local exponential magnetic field growth by radial flows beyond the equipartition value by at least two orders of magnitude on a timescale of a few 100 Myr. Our predictions show that the process can lead to galactic outflows in barred spiral galaxies with a mass-loading factor η ≈ 0.1, in agreement with our numerical simulations. Moreover, our outflow mechanism could contribute to an understanding of the large fraction of barred spiral galaxies that show signs of galactic outflows in the chang-es survey. Extending our model shows the importance of such processes in high-redshift galaxies by assuming equipartition between magnetic energy and turbulent energy. Simple estimates for the star formation rate in our model together with cross correlated masses from the star-forming main sequence at redshifts z ∼ 2 allow us to estimate the outflow rate and mass-loading factors by non-axisymmetric instabilities and a subsequent radial inflow dynamo, giving mass-loading factors of η ≈ 0.1 for galaxies in the range of M ⋆ = 109–1012 M ⊙, in good agreement with recent results of sinfoni and kmos 3D.

The validity of a decentralised simulation-based system for the resolution of Road traffic congestion

Intelligent transport systems are cheaper and easier to implement than other forms of solutions to road traffic congestion. Intelligent Transport Systems (ITS) allow information about road traffic to be collected and transmitted to the Traffic Controllers to respond to traffic congestion appropriately. This research study aims to design and test a simulation-based intelligent transport system for predicting traffic flow patterns. The simulation-based system proposed has a decentralised configuration. Road sections are isolated digitally in a decentralised structure and fed relevant information to predict future traffic states and transmit predicted information to other road sections. Two models of control configuration are created based on the same road network, the first is a decentralised model, and the second is a centralised model (no isolated road sections) to be used as a data source for the decentralised model. The simulated system used decentralised model configurations to predict traffic patterns at road intersections. Due to the lack of actual traffic data, a centralised model serves as the digital twin for the designed decentralised model. The two models were simulated using Anylogic Personal Learning Edition 8.5.2. simulation software, and after testing and result extraction, it was discovered that the decentralised model configuration was not valid for representing the non-uniformity of actual-world traffic patterns. The decentralised model had too few similar inflow and outflow rates to the centralised model in both the complex and straightforward road network cases. However, the decentralised model scored 89% in vehicle population density compared to the centralised model in the simple road network case but could not replicate the good result when the road network becomes complex.

Simulation of the Dispersion of Carbon Dioxide During Accidental Releases from Gas Processing Facilities

Carbon capture and storage (CCS) from oil facilities is an important and effective way to reduce the concentration of carbon dioxide in the atmosphere. Consequently, gas-processing facilities will be dealing with a tremendous quantity of CO2 with high pressure. Therefore, the aim of this study is to simulate the dispersal of CO2 gas leakage from high-pressure pipelines of the gas-processing facilities. The modeling of CO2 leakage from pipelines at CCS process has been problematic because of the lack of appropriate source term models that handle the complex behavior of CO2 correctly during release. In this study, OLGA 7 simulator was utilized for predicting outflow rates and duration of ruptured CO2 pipelines at different leakage scenarios (leakage sizes). OLGA 7 simulator was selected due to its capabilities in simulating gas pipeline leak scenarios in various designs and operating conditions such as Operation Pressure, Isolation valve spacing (IVS), and Emergency response time (ERT). The results of the OLGA 7 simulator provide appropriate source conditions for the selected dispersion models. Gaussian atmospheric dispersion model was chosen to simulate the CO2 gas dispersion behavior within the platform; it is very effective and simple. The effect of operating and design parameters (Operation Pressure, Isolation valve spacing (IVS), and Emergency response time (ERT) on the dispersion behaviors of the released gas in different leak scenarios was studied. The results showed that the emergency response time has the greatest effect on the mass of the accumulated leak (kg) and thus on the level of gas concentrations, and this effect is more pronounced for large leakage sizes. Also, the results showed that the emergency response time had no effect on levels of distance gas concentrations, but it had a significant effect on the duration of the leaking.

Porewater exchange drives nutrient cycling and export in a mangrove-salt marsh ecotone

Coastal wetlands regulate nutrient fluxes from the continents to the oceans. Salt marshes are rapidly encroaching into mudflat area in mangrove wetlands, shaping a mangrove-salt marsh ecotone, with unknown implications to coastal biogeochemical cycles. Here, we hypothesized that nitrogen and phosphorus cycling varied in mangrove and salt marsh, having significant implication on coastal waters. We investigated a tidal creek with a marked mangrove-salt marsh gradient in China using high-frequency time-series sampling of dissolved nutrients and observations of porewater exchange rate across the sediment–water interface over a spring-neap tidal cycle. The nitrogen transformation rates and microbiological activities were also investigated to explain the variability in nitrogen concentrations. The mangrove had net groundwater outflow rates of 3.6–4.3 mm d-1 while the salt marsh had net infiltration of surface water with rates of 0.5–2.9 mm d-1. Salt marsh had less capacity for ammonium (NH4-N) production (mineralization and dissimilatory nitrate reduction to ammonium DNRA) than mangrove. Denitrification dominated nitrogen removal reaching 97% and 83% in mangrove and salt marsh, respectively. Microbe distributions were consistent with nitrogen transformations with larger nirS and nrfA abundances for denitrification and DNRA in the mangrove than salt marsh. The mangrove had a net export of NH4-N but a net import of NOx-N (sum of nitrate and nitrite) and dissolved inorganic phosphorus (DIP) during the monitoring period. In contrast, the salt marsh had lower efflux of nutrient than influx leading to a net nutrient import during the monitoring period. Porewater released from the mangrove had a large DIN:DIP mole ratio (706 ± 236) due to high NH4-N concentrations, while NH4-N in the salt marsh were lower than in the mangrove. Overall, this study revealed that mangrove-salt marsh ecotone will push the native mangrove wetlands from being a source towards a sink of NH4-N to coastal waters by decreasing porewater exchange, modifying the nutrients stoichiometry, and ultimately alleviating the potential of N-associated eutrophication in nearby coastal waters.

Моделирование формирования газового факела оптимальной конфигурации в цементной вращающейся печи

The aim of the work is to study the influence of the conditions of diffusion combustion of natural gas on the efficiency of heat transfer in a cement rotary kiln. The effectiveness of the thermal operation modes of a cement rotary kiln has been evaluated. The mechanism of the influence of the fuel outflow rate from the burner nozzle and the burner inclination on the parameters of diffusion combustion and heat transfer from the standpoint of rational fuel combustion is determined. It has been established that in furnaces of large diameter, the small length of the flame causes overheating of the clinker in the sintering zone of the furnace. The torch becomes too sensitive to the angle of inclination of the burner, so the regulation of combustion is difficult. For furnaces of large diameter, it is preferable to work with a long flame with a uniform temperature distribution along the length. But at the same time, a buoyant force arises, which presses the torch to the top of the furnace. This impairs mixing with air and leads to under burning of the fuel.