Dependence Of Rate Research Articles

Heat removal and ventilation limitations of the solar chimney attached with a built enclosure: Correlations of thermal Rayleigh numbers, port arrangements and discrete heating elements

For energy efficient ventilation and low carbon design, solar chimney has been extensively applied on buildings. In the present work, three representative solar chimneys were introduced, i.e., Model 1 with top-horizontal outlet, Model 2 with upper-vertical outlet and Model 3 with middle-vertical outlet. Updraft ventilation from the built enclosure to the outlet and heat transfer from the absorber to the fluid by heat convection were numerically and theoretically investigated, and their limitations and correlations with governing parameters were also discussed. Streamlines and heatlines were used to visualize transport paths of air and heat respectively. Reverse flow could not be observed in the solar chimney channels of Model 2 and Model 3; Therefore, total volume flow rate induced by the solar chimneys Model 2 and Model 3 and convection heat transfer rate of the absorber increases positively with thermal Rayleigh numbers (Ra). Model 2 chimney produces greater thermal buoyancy than that by Model 3, and its air flow rate is higher than that of Model 3. Generally, volume flow rate induced in Model 1 is higher than those of Model 2 and Model 3 as Ra is no more than 2.5 × 106, and simultaneously, convection heat transfer rate Nusselt number (Nu) is also greater than those of Model 2 and Model 3. When Ra exceeded 2.5 × 106, reverse air flow was intensified further, Nu of Model 1 started to decline. The three models with discrete heat sources could induce more air from indoor than that respective model without discrete heat sources. The maximum increment rate is obtained by the Model 1 solar chimney with discrete heat sources, then Model 2 and the least done by Model 3. Their power relationships between Nu and Ra, V*and Ra are regressed respectively. The dependence of volume flow rate on broad thermal Rayleigh numbers covering all the three flow regimes showed that there were linear correlations between discrete numerical volume flow rates and the scaling predictions, except in Model 1 for high Ra (exceeding critical value 9.0 × 105), where volume flow rate was remarkably reduced due to reverse air flow. This research could provide useful theoretical information for applying small sized vertical solar chimneys attached to the building sidewall to effectively reduce built energy consumption.

Stability of Supersonic Boundary Layer with Internal Heat Supply and Injection of Homogeneous Gas through a Porous Wall

The influence of the Mach number and Reynolds number on the stability of the boundary layer with internal heat supply and homogeneous gas injection through the porous wall is studied. At a fixed Mach numbers, the dependence of perturbation amplification rate on the distance to the plate leading edge is not monotonic. As the Reynolds number increases, the phase velocity tends to the velocity at the inflection generalizing point. Two-dimensional waves are the most growing in the boundary layer. With increasing Mach number and a fixed distance from the plate, edge there is a strong stabilization of the boundary layer. At M=4 the amplification rate maximum decreases in comparison with the corresponding value at M=0 by more than an magnitude order, and the length of the stable boundary layer increases by a factor of 2. At the same time, a frequency at the neutral curve critical point decreases by a factor of about three. It has been establishing that both in the absence of gas injection through a porous wall and in its presence, the internal heat supply has a stabilizing effect on the boundary layer. Within the adopted model of heat supply at M=3 the degree of amplification decreases by about one and a half times in comparison with the case without internal heating of the boundary layer

Dynamical analysis of a chemostat model for 4-chlorophenol and sodium salicylate mixture biodegradation

We consider a mathematical continuous-time model for biodegradation of 4-chlorophenol and sodium salicylate mixture by the microbial strain Pseudomonas putida in a chemostat. The model is described by a system of three nonlinear ordinary differential equations and is proposed for the first time in the paper [Y.-H. Lin, B.-H. Ho, Biodegradation kinetics of phenol and 4-chlorophenol in the presence of sodium salicylate in batch and chemostat systems, Processes, 10:694, 2022], where the model is only quantitatively verified. This paper provides a detailed analysis of the system dynamics. Some important basic properties of the model solutions like existence, uniqueness and uniform boundedness of positive solutions are established. Computation of equilibrium points and study of their local asymptotic stability and bifurcations in dependence of the dilution rate as a key model parameter are also presented. Thereby, particular intervals for the dilution rate are found, where one or three interior (with positive components) equilibrium points do exist and possess different types of local asymptotic stability/instability. Hopf bifurcations are detected leading to the occurrence of stable limit cycles around some interior equilibrium points. A transcritical bifurcation also exists and implies stability exchange between an interior and the boundary (washout) equilibrium. The results are illustrated by lots of numerical examples.

The neural control of movement: a century of in vivo motor unit recordings is the legacy of Adrian and Bronk.

In two papers dated 1928 to 1929 in The Journal of Physiology, Edgar Adrian and Detlev Bronk described recordings from motor nerve and muscle fibres. The recordings from motor nerve fibres required progressive dissection of the nerve until a few fibres remained, from which isolated single fibre activity could be detected. The muscle fibre recordings were performed in humans during voluntary contractions with an intramuscular electrode - the concentric needle electrode - that they describe for the first time in the second paper. They recognised that muscle fibres would respond to each impulse sent by the innervating motor neurone and that therefore muscle fibre recordings provided information on the times of activation of the motor nerve fibres which were as accurate as a direct record from the nerve. These observations and the description of the concentric needle electrode opened the era of motor unit recordings in humans, which have continued for almost a century and have provided a comprehensive view of the neural control of movement at the motor unit level. Despite important advances in technology, many of the principles of motor unit behaviour that would be investigated in the subsequent decades were canvassed in the two papers by Adrian and Bronk. For example, they described the concomitant motor neurones' recruitment and rate coding for force modulation, synchronisation of motor unit discharges, and the dependence of discharge rate on motor unit recruitment threshold. Here, we summarise their observations and discuss the impact of their work. We highlight the advent of the concentric needle, and its subsequent influence on motor control research.

Non-equilibrium thermodynamic modelling of cooling path dependent phase evolution of Li2SiO3 from Li2O-SiO2 melt by considering mixed kinetic phenomena and time-dependent concentration fields

Efficient recovery of Li2SiO3 or other Li compounds from slag streams generating from pyrometallurgical treatment of lithium ion batteries (LIBs) requires fundamental understanding of the kinetics that govern slag solidification. In this work, a non-equilibrium thermodynamic model that incorporates mixed internal kinetics of diffusion and interface mobility, influenced by external cooling paths, is developed to investigate for the first time, the dependence of the phase evolution rate of Li2SiO3 from Li2O-SiO2 melt, on the available driving forces and time-dependent concentration fields. Experiments with different thermal profiles were performed for inverse identification of the kinetic coefficients. It turned out that different cooling rates (1.5Kmin−1, 5Kmin−1 and 10Kmin−1) depict an initial dominance of thermodynamic driving force superseded by kinetic forces in subsequent phase evolution. A certain interface velocity maximum is exhibited during phase formation, where the magnitude decreases progressively from 5.5 × 10−7ms−1 to 3.9 × 10−7ms−1 to 2.1 × 10−7ms−1 with a decrease of the cooling rates.

CALCULATION OF DISSOLVED POLLUTANTS MASS FLOW ACCORDING TO THE DATA OF THEIR CONCENTRATION SPATIAL DISTRIBUTION IN THE SITES OF SMALL PLAINT RIVERS

The paper presents the general solution of the stationary advection-diffusion equa- tion in the integral form for establishing the relationship between the concentration and the total mass flow rate of the pollutant on the plot of the catchment area. The resulting equation was used to solve the inverse problem of estimating the pollutant mass flow rate based on the arbitrary test functions. The unknown dependence of the total mass flow rate on the coordi- nate was represented as a polynomial. The coefficients of polynomials were determined by the least squares method. It was found that the increase in the degree of the polynomial ensures convergence to the exact solution over the entire interval under study. Such a representation describes test functions with high accuracy. When considering randomized concentration dis- tributions, it was established that an increase in the degree of the polynomial leads, on the contrary, to a deviation from the exact solution. These problems were eliminated with the use of the Lasso regularization method, which provides stable solutions to the inverse problem with a minor deviation from the test functions.

Influence of Surface Waves on Liquid-to-Gas Mass Transfer in Molten Silicon

Abstract The paper focuses on the numerical analysis of the mass transfer of impurities from the wavy surface of molten silicon to the gas phase. The mathematical model is described herein, with the modelling of a wavy silicon melt surface being done with the moving mesh technique. The model employs assumptions about the mass transfer process on the surface, namely, that it can be modelled with effective diffusion across the interface. The assumption is verified against limited experimental data for a stationary melt surface, and reasonable agreement is obtained. Thereafter, numerical studies are undertaken for a wavy melt surface. The dependence of impurity removal rate on the wave amplitude, wavelength and frequency is analysed. It is shown that the waves on the surface of the liquid increase the mass transfer rate in a certain parameter range. Finally, results are analysed to find an explanation for this increase and to determine technological factors that impact it. Surface enlargement due to waves and altered flow patterns near the silicon melt are determined as potential reasons for the improved impurity removal rate. A dimensionless criterion for the minimal wave amplitude required to obtain improved impurity removal is found and discussed.

R-modes as a new probe of dark matter in neutron stars

In this work, we perform the first systematic investigation of effects of the presence of dark matter on r-mode oscillations in neutron stars (NSs). Using a self-interacting dark matter (DM) model based on the neutron decay anomaly and a hadronic model obtained from the posterior distribution of a recent Bayesian analysis, we impose constraints on the DM self-interaction strength using recent multimessenger astrophysical observations. We also put new constraints on the DM fraction for this model of DM. The constrained DM interaction strength is then used to estimate DM self-interaction cross section and shear viscosity resulting from DM, which is found to be several orders of magnitude smaller than shear viscosity due to hadronic matter. Assuming chemical equilibrium among DM fermions and neutrons, we estimate the bulk viscosity resulting from the dark decay of neutrons considering different scenarios for the temperature dependence of the reaction rate and investigate the effect on the r-mode instability window. We conclude that DM shear and bulk viscosity may significantly modify the r-mode instability window compared with the minimal hadronic viscosities, depending on the temperature dependence of the process. We also found that for the window to be compatible with the X-ray and pulsar observational data, the rate for the dark decay process must be fast.

ASSESSMENT OF THE INFLUENCE OF CONTAMINATION OF THE BOTTOMHOLE ZONE OF THE FORMATION ON THE PERFORMANCE CHARACTERISTICS OF PRODUCTION WELLS

The reasons for the decrease in productivity of gas wells are characterized. The structure of the formation colmatation parameter is revealed. For the conditions of a model well, using mathematical dependencies, the influence of different values of the radii of the contaminated zone at the bottomhole formation zone, the multiplicity of the permeability coefficient of the contaminated formation zone and different degrees of reduction in reservoir pressure from the initial value on the productivity of gas wells was studied. The research results are presented in the form of graphical dependences of gas flow rate for the initial value of reservoir pressure on the permeability coefficient of the contaminated zone for different radii of the contaminated zone, on the radius of the contaminated zone for different values of the permeability coefficient of the contaminated zone, pressure along the radius of the contaminated zone 0.25, on the radius of the zone pollution of varying degrees of reduction in reservoir pressure according to the multiplicity of the permeability coefficient of the contaminated zone 2. According to the results of studies, with an increase in the multiplicity of the permeability coefficient of the contaminated zone, we will obtain a significant decrease in the gas flow rate, and the gas flow rate, the greater the value of the reservoir pressure. Zone contamination at high values of reservoir pressure has a significant impact on the reduction in gas production. Using the method of statistical processing of calculated data, the average optimal value of the contaminated zone radius was established to be equal to 0.25 for all values of the permeability coefficient of the contaminated zone and the average optimal value of the permeability coefficient of the contaminated zone to be 1.97.

ASSESSMENT OF THE ACTUAL TEMPERATURE CONDITIONS IN THE CHAMBERS FOR PLACING FANS

Purpose. Assessment of the actual temperature conditions in the chambers of gas suction installations in the mining and geological conditions of the “Pokrovske” Mine Administration. Method. Analysis and generalisation of the results of observations of the actual temperature regime in the fan chambers of the component installations. Results. An analytical comparison of the actual temperature regime in the chambers of gas suction units with the permissible one according to sanitary and hygienic standards was carried out. The rational parameters of the temperature regime are determined, which can be considered “conditionally” acceptable in the chambers of gas suction units, are determined in the mining and geological conditions of the “Pokrovske” Mine Administration. Scientific novelty The substantiation of the necessary physical parameters of the air entering the chambers of gas suction installations, for their ventilation, to ensure sanitary and hygienic standards for temperature has been carried out. The dependence of the air flow rate entering the chambers of ventilation gas suction units on its maximum allowable value , according to sanitary and hygienic standards, has been established.. Practical significance. It has been established that in order to ensure the standard temperature regime in the chambers of gas suction units in the mining and geological conditions of the “Pokrovske” Mine Administration, it is not advisable to use refrigeration units. This will reduce the economic costs of ensuring the standard temperature regime. Key words: recommendations, methane, goaf, temperature, ventilation.

Assessing Memory in Convection Schemes Using Idealized Tests

AbstractTwo assumptions commonly applied in convection schemes—the diagnostic and quasi‐equilibrium assumptions—imply that convective activity (e.g., convective precipitation) is controlled only by the large‐scale (macrostate) environment at the time. In contrast, numerical experiments indicate a “memory” or dependence of convection also on its own previous activity whereby subgrid‐scale (microstate) structures boost but are also boosted by convection. In this study we investigated this memory by comparing single‐column model behavior in two idealized tests previously executed by a cloud‐resolving model (CRM). Conventional convection schemes that employ the diagnostic assumption fail to reproduce the CRM behavior. The memory‐capable org and Laboratoire de Météorologie Dynamique Zoom cold pool schemes partially capture the behavior, but fail to fully exhibit the strong reinforcing feedbacks implied by the CRM. Analysis of this failure suggests that it is because the CRM supports a linear (or superlinear) dependence of the subgrid structure growth rate on the precipitation rate, while the org scheme assumes a sublinear dependence. Among varying versions of the org scheme, the growth rate of the org variable representing subgrid structure is strongly associated with memory strength. These results demonstrate the importance of parameterizing convective memory, and the ability of idealized tests to reveal shortcomings of convection schemes and constrain model structural assumptions.

Relaxation of the trapped magnetic flux in a mesoscopic HTS with artificial pinning in the form of submicron holes

Vortex relaxation has been studied in a microsized HTS with various distributions of artificial pinning in the form of submicro-holes. It has been shown that, in some cases, for a superconductor with dimensions up to several micrometers, the time dependences of the trapped magnetic field do not correspond with the collective creep model. The dependences of the trapped-field relaxation rate and vortex activation energy on the magnetizing field (up to 0.5 T) and temperature (up to 50 K) have been obtained. It has been shown that the presence of submicro-holes slightly increases the relaxation rate, mainly due to the decrease in the number of random nanosized pinning centers.

Explosive dynamics of double tearing mode in Tokamak

Using the CLT code, the resistivity dependence of the reconnection rate during the explosive phase at various separations of two rational surfaces of m/n = 3/1 double tearing mode is investigated quantitatively. Our study focuses on the explosive reconnection process where the exchange of island positions takes place and no secondary island forms. The negative dependence of explosive reconnection rate on resistivity in low resistivity and the systematic study of the effect of the separation on the resistivity dependence in high resistivity have been studied for the first time. The negative dependence is qualitatively different from the results in some relative studies where it usually exhibits a positive dependence on the resistivity or is independent of the resistivity. The negative dependence in two regions with a low resistivity, with a high resistivity and a large separation is caused by different reasons: one is the thickness of the current sheet, and the other is the separation.

A numerical model for the transport and drying of solutions in thin porous media — Coffee-stain effect and solute ring formation

We have developed a comprehensive numerical model for the transport and drying of solutions in thin porous media that consist of permeable fibers such as paper. We explicitly account for the gas-phase transport dynamics. Moreover, we introduce an empirical relation for the concentration- and molecular-weight dependence of the pore-fiber transport rate of the solutes. These two key elements enable us for the first time to realistically model two important phenomena relevant to inkjet printing technology. The first is the equivalent of the coffee-stain effect for dilute solutions in porous media. The second is the formation of solute rings for concentrated aqueous mixtures of compounds with a molecular weight significantly above that of water. Whereas the first is governed by spatially non-uniform solvent evaporation, the second case is dominated by solvent-mediated pore-fiber transport. We achieved a good qualitative agreement with the available experimental data.

High‐Temperature Creep Behavior of Selective‐Laser‐Melting‐Fabricated Lattice Structures Inspired from Euplectella Aspergillum

In this study, the lattice‐like arrangement of Euplectella aspergillum is used to derive bionic grid‐stiffened structures in the form of thin tubes. The bionic tubes are 3D printed with AlSi10Mg alloy using a selective laser melting process. High‐temperature creep behavior at 250 °C and stress (0.3–0.7) times yield strength of the tubes is studied under uniaxial constant compressive load. The effect of the stress level, temperature, and tube design on the creep performance and deformation behavior is studied. The creep performance of bioinspired tubes is compared with honeycomb lattice tubes. In the results, the dependence of creep life and creep rate on the design of the bionic tubes is shown. E. aspergillum–based thin tubes show higher creep life and lower creep rate as compared to honeycomb‐based tubes at all stress levels. Also, the creep curves of lattice structures based thin tubes are different than the solid material, especially in the primary and tertiary regions. The fractography analysis shows higher creep life in E. aspergillum–inspired thin tubes is due to the improvement in ductility at high temperature. The stress exponent value in the Mukherjee–Bird–Dorn equation shows that the mechanism of creep is diffusion. Herein, in the results, it is shown that the bioinspiration and additive manufacturing provide an opportunity to design and fabricate advanced iso‐grids structures.

Modelling cowpea beans [formula omitted]-galactosidase inactivation dependence on temperature and moisture content

Hydrothermal treatment improves the digestibility of pulses through the coupled phenomena of enzymatic degradation and diffusion of galacto-oligosaccharides, despite the thermal inactivation of α-galactosidase at mild temperatures. To better understand the key process parameters that influence the balance between enzyme activity and its inactivation, the kinetics of α-galactosidase inactivation were investigated in a cowpea-water system at a broad range of temperatures (45 °C ≤T≤ 60 °C), moisture contents (0.16 g/g dry basis, d.b. ≤W≤ 0.85 g/g d.b.) and treatment times (5 min ≤t≤ 7.5 h). For moisture contents ranging from 0.25 to 0.85 g/g d.b., the higher the temperature the faster the inactivation of α-galactosidase; while for 0.16 g/g d.b., the relative enzymatic inactivation was not temperature-dependent. A first-order model was successfully fitted to the experimental data, whereas the temperature dependence of inactivation rate followed the Arrhenius model. The influence of moisture content on the enzymatic inactivation rate was remarkable. The inactivation rate constant at excess water (0.85 g/g d.b.) was five times higher than the samples at limited water (0.35 g/g d.b.) condition. The results showed moisture-dependent α-galactosidase inactivation kinetics mainly at mild temperatures (55 and 60 °C), with implications for the representation of diffusion-reaction phenomena during hydrothermal processing of pulses.

Refractive index dependence of the radiative rate of a magnetic dipole transition for a nanoparticle system

The emission spectra of Cs2NaEuCl6 nanoparticles (NPs) synthesized by the hot injection method are interpreted. Dispersion of the NPs in alkane solvents experimentally enables the magnetic dipole radiative rate in vacuum for the 5D0 - 7F1 channel to be determined as 14.7 ± 0.1 s−1, in agreement with the calculated value.

The Galactic Interstellar Object Population: A Framework for Prediction and Inference

The Milky Way is thought to host a huge population of interstellar objects (ISOs), numbering approximately 1015 pc−3 around the Sun, which are formed and shaped by a diverse set of processes ranging from planet formation to Galactic dynamics. We define a novel framework, first to predict the properties of this Galactic ISO population by combining models of processes across planetary and Galactic scales, and second to make inferences about the processes being modeled, by comparing the predicted population to what is observed. We predict the spatial and compositional distribution of the Galaxy’s population of ISOs by modeling the Galactic stellar population with data from the APOGEE survey and combining this with a protoplanetary disk chemistry model. Selecting the ISO water mass fraction as an example observable quantity, we evaluate its distribution both at the position of the Sun and averaged over the Galactic disk; our prediction for the solar neighborhood is compatible with the inferred water mass fraction of 2I/Borisov. We show that the well-studied Galactic stellar metallicity gradient has a corresponding ISO compositional gradient. We also demonstrate the inference part of the framework by using the current observed ISO composition distribution to constrain the parent star metallicity dependence of the ISO production rate. This constraint, and other inferences made with this framework, will improve dramatically as the Vera C. Rubin Observatory Legacy Survey of Space and Time progresses and more ISOs are observed. Finally, we explore generalizations of this framework to other Galactic populations, such as that of exoplanets.

Chronic kidney disease in patients with chronic heart failure infected with human immunodeficiency virus

Chronic kidney disease (CKD) is the most common manifestation of target organ damage in chronic heart failure (CHF). The aim of the study was to determine the risk factors associated with the course of CKD in patients with CHF infected with the human immunodeficiency virus (HIV). According to the results obtained, the prevalence of CKD among HIV-infected patients with CHF is 58.82%, which is 4 times more common than in patients with HIV infection without CHF. The dependence of glomerular filtration rate (GFR) on three main factors that reflect damage to the heart muscle – blood plasma NT-proBNP concentration, left ventricular ejection fraction (LVEF%) and left ventricular myocardial mass index (LVMI) was proved, which together, being included in the regression model, determine 42.2% of the variance of GFR values and are decisive in the development of CKD in patients with CHF on the background of HIV infection. The concentration of NT-proBNP in the blood plasma of patients with CHF equal to or greater than 683.65 pg/ml can be considered as a diagnostic criterion for the development of CKD in HIV-infected people with a sensitivity of the method of 75.0% and a specificity of 75.4%, respectively. In addition, risk factors for the development of CKD in patients with CHF and HIV infection are smoking, alcohol and drug use, a history of chronic and acute forms of coronary artery disease, atrial fibrillation, ventricular arrhythmias, diabetes mellitus, chronic viral hepatitis C, anemia and thrombocytopenia. Patients with CHF and CKD have a more rigid arterial wall – there is a significant excess of the stiffness indices of the aorta and peripheral arteries. Long-term use of antiplatelet agents, NRTIs, NNRTIs, and protease PIs may aggravate the course of CHF in HIV-infected people with CKD manifestations.

Flux exchange between fracture and matrix dictates late-time tracer tailing

Understanding and quantifying the solute tailing process in fractured rocks is critical for various subsurface applications but remains challenging. Particularly, the effects of flux exchange between fracture and matrix on the tailing process are considered to be important but have not been explicitly investigated. To fill this knowledge gap, we estimate the power-law scaling of late-time tracer tailing, n, based on three dimensional direct numerical simulations that consider both solute diffusion and advection across fracture-matrix interface. The dependence of solute decay rate n on fracture-matrix interaction is elucidated by simulating cases over a wide range of matrix permeability (km). In the case with matrix diffusion but without advection between fracture and matrix, we find that matrix diffusion significantly enhances tracer tailing. Then, the consideration of advection does not show significant effect on n up to the matrix permeability km of 10−12 m2. When k is greater than 10−12 m2, n declines rapidly down to 1.0 at k = 10−9 m2. We finally demonstrate that the upscaled model of continuous time random work can capture the late-time tailing behavior. This study provides a mechanistic explanation for the heavy tailing process commonly observed in fractured rocks.