ALMA Imaging of a Galactic Molecular Outflow in NGC 4945

We present the ALMA detection of molecular outflowing gas in the central regions of NGC 4945, one of the nearest starbursts and also one of the nearest hosts of an active galactic nucleus (AGN). We detect four outflow plumes in CO J = 3 − 2 at ∼0.″3 resolution that appear to correspond to molecular gas located near the edges of the known ionized outflow cone and its (unobserved) counterpart behind the disk. The fastest and brightest of these plumes has emission reaching observed line-of-sight projected velocities of over 450 km s−1 beyond systemic, equivalent to an estimated physical outflow velocity v ≳ 600 km s−1 for the fastest emission. Most of these plumes have corresponding emission in HCN or HCO+ J = 4 − 3. We discuss a kinematic model for the outflow emission where the molecular gas has the geometry of the ionized gas cone and shares the rotation velocity of the galaxy when ejected. We use this model to explain the velocities we observe, constrain the physical speed of the ejected material, and account for the fraction of outflowing gas that is not detected due to confusion with the galaxy disk. We estimate a total molecular mass outflow rate M ̇ mol ∼ 20 M ⊙ yr−1 flowing through a surface within 100 pc of the disk midplane, likely driven by a combination of the central starburst and AGN.

FOCUS ON ARTIFICIAL INTELLIGENCE FOR PREDICTING THE OUTFLOW OF CLIENTS FROM ON-LINE EDUCATION SITES

The article examines the process of forecasting customer outflows, which is especially important for companies that use a business model based on subscription. It was found that the outflow rate is extremely important for companies with a subscription and transactional business model, which implies regular payments to the company (banks, telecom operators, SaaS-services, etc.). For this purpose, the types, the main reasons for the outflow of customers and the parameters defined to build a predictive model using machine learning algorithms were considered. The result was the hypothesis of the reasons for the outflow of customers from sites that provide training services based on courses that are presented on-line in the Internet space. To build a model of outflow forecasting, the behavioral characteristics of students, their motivation and the structure of the courses themselves were studied. Based on the collected large array of data, their change was analyzed by a large number of parameters and the relationships between the behavioral characteristics of students, course structures and their passage were identified. A variant of the forecasting model was built, for which the accuracy of its operation was increased and the results were integrated into the customer outflow prediction module. The final list of features included more than 100 parameters, which were divided into 6 blocks. As a result, a predictive model was created using the Weibull distribution, as client behavior can be considered as a kind of survival model. To estimate the probability of customer outflow, based on the considered hypotheses, a recurrent neural network with an LSTM layer was developed, where a negative logarithmic likelihood function was used as a loss function for the Weibull distribution. As a conclusion, it was proposed to introduce a stable proactive educational business, when decisions are made not only on the basis of feelings, but also on the basis of data, comes a clearer and more sound understanding of how to improve the educational product.

The Prospects of Abrasive Treatment of Tough-To-Machine Materials

In current conditions, great attention is paid to the quality of parts, which is in many ways determined by finishing operations of mechanical treatment, with surface grinding being the most widespread. Grinding process efficiency, abrasive tool wear intensity, machined surface quality and other features of grinding process depend on properties of the environment, where the cutting process takes place. Forced changing of conditions of this environment is one of the ways to control and optimize the grinding process, which can be reached due to finding new technological decisions. One of the most promising directions to solve this problem is the process of face grinding with discontinuous grinding tool and supply of cooling fluid or air in the cutting zone directly. Carried analysis of features of face grinding has shown that heat density can be decreased by the usage by grooved wheels with vortex air cooling or by supply of cooling-lubricant technological fluid. Obtained dependences of temperature field of part surface during grinding establish the influence of the length of working shoulders and grooves, vortex tubes number, outflow rate, temperature and flow rate of cold vortex flow of air. These data provide conscious control over the process of discontinuous face grinding by changing wheel grain size and grinding speed.

Numerical Analysis of Sand Bed Degrading and Sediment Transport Rate Under Tailings Dam Break

Dam-breaking accidents in tailings ponds may result in loss of tailings, damage to the downstream bridges and houses, flooding of farmland and roads, hazards to the local environment, and even loss of property and lives. Therefore, research on dam breaks in tailings reservoirs and prediction of subsequent impacts are of great significance. This paper describes theoretical and numerical analyses of the retrogressive erosion model and calculations of the sand bed surface profile and sediment transport rate following tailings dam break events. The calculation results show that the degrading rate of the bed surface in the reservoir area reaches a maximum when the breach is formed and then rapidly decreases to a stable value. Farther away from the breach, the peak degrading rate of the bed surface is lower. The time of the peak tailings outflow rate is related to the formation of the breach. A larger breach has a shorter formation time and a greater peak flow.

Gas-Kick Simulation in Oil-Based Drilling Fluids with Nonequilibrium Gas-Dissolution and -Evolution Effects

Summary The nonequilibrium dissolution and evolution characteristics of gas in oil-based drilling fluids (OBDFs) greatly affect the ratio of free gas to dissolved gas in the wellbore, thus influencing the prediction accuracy of the wellbore-pressure and surface responses. Previous equilibrium-state models can result in the incorrect estimation of the multiphase-flow parameters during a gas kick in OBDFs. Therefore, a nonequilibrium gas/liquid two-phase-flow model is developed for simulations of gas kicks in OBDFs. Nonequilibrium gas-kick behaviors in OBDFs are investigated using the proposed model, and it is concluded that there is a unique gas-dissolving stage in comparison to the equilibrium gas-kick conditions. In this stage, the pit gain decreases to a large extent, and this phenomenon can be misinterpreted by the drilling crew as a loss of circulation or a decrease in the gas-kick intensity. The drilling-fluid-outflow rate is not a reliable gas-kick indicator because of the lower increment in the drilling-fluid-outflow rate under both nonequilibrium and equilibrium gas-dissolution conditions. Neglecting the gas-evolution rate in OBDFs could lead to overestimations of the maximum pit gain and the drilling-fluid-outflow rate. More gas moves from the wellbore in the form of dissolved gas under noninstantaneous gas-evolution conditions. The results of this study provide a theoretical basis for the safe and efficient treatment of gas kicks in OBDFs.

A New Dam-Break Outflow-Rate Concept and Its Installation to a Hydro-Morphodynamics Simulation Model Based on FDM (An Example on Amagase Dam of Japan)

Dams are constructed to benefit humans; however, dam-break disasters are unpredictable and inevitable leading to economic and human life losses. The sequential catastrophe of a dam break directly depends on its outflow hydrograph and the extent of population centers that are located downstream of an affected dam. The population density of the cities located in the vicinity of dams has increased in recent times and since a dam break hydrograph relies on many uncertainties and complexities in devising a dam-break outflow hydrograph, more researches for the accurate estimation of a dam-break flood propagation, extent and topography change becomes valuable; therefore, in this paper, the authors propose a novel and simplified dam-break outflow rate equation that is applicable for sudden-partial dam breaks. The proposed equation is extensively affected by a dam-break shape. Therefore, the inference of a dam-break shape on a dam-break outflow rate is investigated in the current study by executing hydraulic experiments in a long, dry bed, frictionless and rectangular water channel connected to a finite water tank to acquire a mean break-shape factor. The proposed equation is further validated by regenerating the Malpasset dam-break hydrograph and comparing it to the existing methods and also by installing it on an existing 2D hydro-morphodynamics flood simulation model. Finally, Amagase Dam’s (arch-reaction dam in Japan) break simulation is executed as a case study. The results of the simulations revealed that the greater the height of a dam-break section, the more devastating its flood consequences would be.

Filtration and Backwashing Studies: Obafemi Awolowo University Waterworks as A Case Study

This research centres on the study of the filtration and backwashing operations of the filtration unit of the Opa Waterworks and a detailed laboratory study of the filtration and backwashing characteristics of the filter medium being used at the treatment plant. A detailed study of the filtration unit of Opa Waterworks was undertaken with particular emphasis placed on the estimation of the volume of water used during backwashing, the backwashing procedure and the average backwashing time. Specific properties of the filter medium used in the gravity filter such as porosity, density, equivalent density, specific gravity and unhindered settling velocity were investigated in the laboratory. The backwashing properties of the filter medium was also studied using the DSF (Dynamic Shape Factor) and Sphericity models and the predicted results obtained were compared to the actual laboratory results. Based on works carried out, the volume of wash-water required for the gravity filters was estimated as 14,200 litres (14.2 m3) which is about 3.12% of the total volume of the clear water tank, with an outflow rate of 0.01 m3/s. The accuracy of the Blake – Kozeny equation in predicting head loss across a filter bed using clean water runs was investigated and found to be reasonably accurate, and the prediction errors

Effect of extrusion on the rumen undegradable protein fraction of lupins

Lupins are highly degradable in the rumen, and do not provide enough bypass protein for high-producing ruminant animals. The effects of extrusion on dry matter (DM) and crude protein (CP) rumen degradability of Lupinus albus and Lupinus angustifolius were determined in situ. Samples of both types of lupin were extruded at maximum temperature, which reached 116 °C. Six Dohne Merino wethers fitted with rumen cannulas were used in this trial. Samples were incubated in the rumen at intervals of 0, 2, 4, 12, 36, and 48 hours. This procedure was repeated in two sheep per treatment and in three periods, giving a total of six observations for each variable. Extrusion lowered the soluble fraction of CP and increased the potential degradable fraction without affecting its rate of degradation. It also lowered the effective degradability of CP of both types of lupin by 28% at an outflow rate of 0.08% per hour. No differences were observed between types. Extrusion modified the ruminal degradation parameters and decreased effective rumen degradation, especially at faster outflow rates. Thus, the rumen undegradable protein (RUP) fraction of lupins was increased by extrusion and lupins could be used more efficiently in ruminant diets. This study showed that the benefits of extrusion could be reached at a relatively low temperature of 116 °C to reduce the possibility of heat damage.

Complex structure of a proto-brown dwarf

We present ALMA 12CO (2-1), 13CO (2-1), C18O (2-1) molecular line observations of a very young proto-brown dwarf system, ISO-OPH 200. We have conducted physical+chemical modelling of the complex internal structure for this system using the core collapse simulations for brown dwarf formation. The model at an age of ∼6000 yr can provide a good fit to the observed kinematics, spectra, and reproduce the complex structures seen in the moment maps. Results from modelling indicate that 12CO emission is tracing an extended (∼1000 au) molecular outflow and a bright shock knot, 13CO is tracing the outer (∼1000 au) envelope/pseudo-disc, and C18O is tracing the inner (∼500 au) pseudo-disc. The source size of ∼8.6 au measured in the 873μm image is comparable to the inner Keplerian disc size predicted by the model. A 3D model structure of ISO-OPH 200 suggests that this system is viewed partially through a wide outflow cavity resulting in a direct view of the outflow and a partial view of the envelope/pseudo-disc. We have argued that ISO-OPH 200 has been mis-classified as a Class Flat object due to the unusual orientation. The various signatures of this system, notably, the young ∼616 yr outflow dynamical age and high outflow rate (∼1 × 10−7 M⊙ yr−1), silicate absorption in the 10$\rm{\mu m}$ mid-infrared spectrum, pristine ISM-like dust in the envelope/disc, comparable sizes of the extended envelope and outflow, indicate that ISO-OPH 200 is an early Class 0 stage system formed in a star-like mechanism via gravitational collapse of a very low-mass core.