Transfer Model Research Articles

Radon over Kimberlite Pipes: Surface Field Experiments and Calculations of Vertical Diffusion (Arkhangelsk Diamondiferous Province, NW Russia)

We present the results of field and experimental studies to assess the influence on the formation of the radon field over the kimberlite pipes of the Arkhangelsk diamondiferous province. Measurements were made in the field to establish the radon radiation in the soil air and the gas permeability of soils in the area of the Chidvinskaya pipe. Experimental work was aimed at determining the radiation and physical parameters of the rocks occurring within the kimberlite field. Based on a set of field and experimental data, a model of the diffusion transfer of radon in the area of the Chidvinskaya pipe was calculated for three profiles, represented by the rocks of the pipe, sedimentary rocks of the exocontacts of the pipe, and host sandy and clay sedimentary rocks. The results of the calculations show that the rocks of the exocontacts of the pipe have the greatest potential for increased radon radiation. The calculated values of the radon radiation produced by these rocks exceeded 9000 Bq·m−3. The diatreme kimberlites produced the lowest radon radiation. We showed that the source of the increased values of radon radiation is the rocks of the pipe’s exocontacts. This fact will make it possible to use the emanation method as an additional one for the search for kimberlite pipes.

A change in the air temperature inside a 20-liter chamber when air is added from the receiver

Introduction. One of the reasons for the overestimation of the explosion hazard of dust inside a (20 ± 2)-liter chamber is the elevated initial temperature of the air suspension. The initial temperature is also raised by the process of filling the pre-emptied chamber with air from the receiver, used to distribute dust over the chamber. In this work, an increase in the air temperature inside an 18.7-liter chamber was identified in an experiment for the case of addition of air from the receiver.The methodology of an experiment. The air temperature in the chamber was measured at the time when the air from the receiver was added using a WR 5/20 thermoelectric converter (a thermocouple). The thermocouple junction was located at the distance of 70 mm from the inner wall of the chamber. The thermocouple signal was processed by an MCLab PRO programmable logic controller (the time resolution is 1 ms).Research results. The measuring instruments recorded an increase in the temperature of the thermocouple junction by +14 degrees. Due to the comparability of the inertia of the thermocouple (3 s) and the characteristic time of air cooling by the chamber walls (5 s), the measurement results underestimated the real value of a jump in the air temperature inside the chamber. Measurement results were refined using a simple model of heat transfer between the objects involved in the process (thermocouple junction – air – chamber wall) that entailed the exponential relaxation of the temperature difference over time. As a result, an estimated increase in the initial temperature inside the chamber of +30 degrees was identified.Results and discussion. The temperature jump by +30 degrees makes a noticeable contribution to the total jump in the initial temperature, which was previously tied solely to the burnout of the ignition source (+80 degrees).Conclusions. Given the known increase in the temperature inside the chamber caused by the burnout ofa standard ignition source (2 kJ), the real value of the initial temperature of the environment can reach 135 °C in the course of studying dust in a (20 ± 2)-liter chamber.

Computational Implementation of a Mixed-Dimensional Model of Heat Transfer in the Soil–Pipe System in Cryolithic Zone

Computational Implementation of a Mixed-Dimensional Model of Heat Transfer in the Soil–Pipe System in Cryolithic Zone

Thermal characteristics of longitudinal fin with Fourier and non-Fourier heat transfer by Fourier sine transforms

The quest for high-performance of heat transfer components on the basis of accommodating shapes, smaller weights, lower costs and little volume has significantly diverted the industries for the enhancement of heat dissipation with variable thermal properties of fins. This manuscript proposes the fractional modeling of Fourier and non-Fourier heat transfer of longitudinal fin via non-singular fractional approach. The configuration of longitudinal fin in terms of one dimension is developed for the mathematical model of parabolic and hyperbolic heat transfer equations. By considering the Fourier and non-Fourier heat transfer from longitudinal fin, the mathematical techniques of Fourier sine and Laplace transforms have been invoked. An analytic approach is tackled for handling the governing equation through special functions for the fractionalized parabolic and hyperbolic heat transfer equations in longitudinal fin. For the sake of comparative analysis of parabolic verses hyperbolic heat conduction of fin temperature, we depicted the distinct graphical illustrations; for instance, 2-dimensional graph, bar chart, contour graphs, heat graph, 3-dimensional graphs and column graphs on for the variants of different rheological impacts of longitudinal fin.

DNA/RNA heteroduplex oligonucleotide technology for regulating lymphocytes in vivo

Manipulating lymphocyte functions with gene silencing approaches is promising for treating autoimmunity, inflammation, and cancer. Although oligonucleotide therapy has been proven to be successful in treating several conditions, efficient in vivo delivery of oligonucleotide to lymphocyte populations remains a challenge. Here, we demonstrate that intravenous injection of a heteroduplex oligonucleotide (HDO), comprised of an antisense oligonucleotide (ASO) and its complementary RNA conjugated to α-tocopherol, silences lymphocyte endogenous gene expression with higher potency, efficacy, and longer retention time than ASOs. Importantly, reduction of Itga4 by HDO ameliorates symptoms in both adoptive transfer and active experimental autoimmune encephalomyelitis models. Our findings reveal the advantages of HDO with enhanced gene knockdown effect and different delivery mechanisms compared with ASO. Thus, regulation of lymphocyte functions by HDO is a potential therapeutic option for immune-mediated diseases.

Mathematical Model of Fluid Flow and Solute Transfer in a Permeable Channel with Slip Velocity at the Boundaries

Mathematical Model of Fluid Flow and Solute Transfer in a Permeable Channel with Slip Velocity at the Boundaries

Research on Low-Speed Driving Model of Ultrasonic Motor Based on Beat Traveling Wave Theory

This paper proposes a driving method, the superimposed pulse driving method, that can make an ultrasonic motor run at a low speed. Although this method solves the periodic oscillation of speed in a traditional low-speed driving motor, it still has a small periodic fluctuation, which affects the stability of the speed. To reduce the fluctuation rate of the motor speed, the structure model and driving model of the motor are established, based on the theory of a beat traveling wave, and the motion characteristics of the particle point are analyzed in this paper. The simulation curve of the motor speed is obtained according to the stator and rotor contact model and the transfer model. The research shows that the driving method introduced in this paper causes the stator surface to generate a traveling beat wave, and the driving end of the stator generates an intermittent reciprocating vibration and drives the rotor rotation, which is the mechanism of low-speed operation when the driving method is used to drive the motor, as well as the reason for the periodic fluctuation of the motor speed. To improve the speed stability, this paper controlled the output performance of the motor by changing the two control variables—prepressure and frequency difference—and concluded that the variation trend of the average speed and speed volatility were consistent with the variation trend of the motor’s average speed determinant and the speed volatility determinant, respectively, which is verified by the velocity measurement experiment and the vibration measurement experiment. These insights lay the theoretical foundation for the velocity adjustment and stability optimization and, finally, the application of the new driving method is prospected.

Modeling of Melt Flow and Heat Transfer in Stationary Gas Tungsten Arc Welding with Vertical and Tilted Torches.

A 3D numerical simulation was conducted to study the transient development of temperature distribution in stationary gas tungsten arc welding with filler wire. Heat transfer to the filler wire and the workpiece was investigated with vertical (90°) and titled (70°) torches. Heat flux, current flux, and gas drag force were calculated from the steady-state simulation of the arc. The temperature in the filler wire was determined at three different time intervals: 0.12 s, 0.24 s, and 0.36 s. The filler wire was assumed not to deform during this short time, and was therefore simulated as solid. The temperature in the workpiece was calculated at the same intervals using heat flux, current flux, gas drag force, Marangoni convection, and buoyancy. It should be noted that heat transfer to the filler wire was faster with the titled torch compared to the vertical torch. Heat flux to the workpiece was asymmetrical with both the vertical and tilted torches when the filler wire was fully inserted into the arc. It was found that the overall trends of temperature contours for both the arc and the workpiece were in good agreement. It was also observed that more heat was transferred to the filler wire with the 70° torch compared with the 90° torch. The melted volume of the filler wire (volume above 1750 °K) was 12 mm3 with the 70° torch, compared to 9.2 mm3 with the 90° torch.

Numerical modeling of open pit ventilation when varying the location of the dust and gas cloud

Research objective is to estimate the effect of bulk explosion location and the initial height of the dust and gas cloud on open-pit natural ventilation time and the level of air contamination of the upper edge of the open pit down the wind. Methods of research. Computer modeling of aerodynamics and gaseous component transfer in the 2D geometry is carried out with the COMSOL software. To calculate the aerodynamic characteristics, the approximation of the incompressible fluid with the standard k–ε turbulence model was carried out. Gaseous component distribution was modeled using the numerical solution to the convection-diffusion equation of contaminant transfer. Numerical experiments under the fixed initial concentration of the gaseous component and the speed of the incoming wind flow have been carried out for three locations of bulk explosions and six values of the initial height (from 70 to 420 m with a step of 70 m) of the dust and gas cloud. Research results and analysis. Spatial distributions of the model’s aerodynamic characteristics and contaminants gaseous component when reaching the maximum permissible concentration in the modeled area have been obtained. The estimated time of the open-pit natural ventilation and the dynamics of the open-pit upper edge air contamination dynamics down the wind have been analyzed. The complex and diversified nature of open pit ventilation for various locations of bulk explosions has been recorded. The undulating character of contaminant loss has been predicted (with different heights of peaks) conditioned by the presence of vortex formation in the open pit. Conclusion and scope of results. For the recirculation scheme of ventilation, the situations with the bulk explosion locations shifted to the windward edge of the open pit are the longest. It has been shown that the reduction in the dust and gas cloud lift does not always ensure the reduction in the contamination level at the upper edge of the open pit down the wind.

A forest-fire model for technology risk transfer

Based on the transmission characteristics of networks and the systematization of technical risks in national major science and technology projects, the risk transmission mechanism of national major science and technology projects is deeply discussed herein. Firstly, the system of systems (SoS) engineering process model of national major science and technology projects is constructed, including two levels and three stages. Secondly, the hierarchical structure of national major science and technology projects is analyzed, and the risks are divided into different levels, such as SoS, system, subsystem, equipment, module, and components. Finally, we describe the risk transfer mechanism using the forest-fire model and outline a risk control strategy. The results show that the findings are helpful for recognizing the essence and transmission mechanism of technical risks of national major science and technology projects and for reducing the risk from the source. The research results can be applied to project management in the transportation field.

An Anti-Interference Control Method for an AGV-WPT System Based on UIO-SMC

During the wireless charging of an automated guided vehicle (AGV), the output voltage is unstable due to changes in parameters such as coil mutual inductance and load resistance caused by external interferences and internal mismatches of the system. In this paper, an integral sliding mode control method based on an unknown input observer (UIO) containing predictive equations is designed to build an inductor–capacitor–capacitor-series (LCC-S) topology model for wireless power transfer (WPT). The observer designed by this method can perceive changes in the secondary resistance parameter and the mutual inductance of the primary and secondary coils. The design with the prediction equation speeds up the convergence of the observer to the true value. The observer’s compensation of the control system avoids the occurrence of integral oversaturation. The experimental results show that, based on the UIO-SMC system output, voltage can be accurately controlled to meet the requirement for a given voltage. The effect of suppressing disturbance is better than with SMC and PI control. When the system parameter changes, it has better voltage anti-interference performance and stronger ripple suppression.

Investigation of Radiative-Conductive Heat Transfer by Noncontact Measurements. Identification of Mathematical Models of Heat Transfer for Nontransparent Materials

Investigation of Radiative-Conductive Heat Transfer by Noncontact Measurements. Identification of Mathematical Models of Heat Transfer for Nontransparent Materials

Numerical Simulation of a Periodic Quasi-Switching Mode of Flow around a Conical Dimple with a Slope Angle of 10 Degrees on the Wall of a Narrow Channel Using URANS

The applicability of the solution of the unsteady Reynolds-averaged Navier–Stokes equations (URANS) for the numerical simulation of the periodic quasi-switching regime of vortex generation and heat transfer in a deep conical dimple with a slope angle of 10∘ on the wall of a narrow channel is substantiated. To calculate the turbulent regime, the model of shear stress transfer by Menter 2003, modified taking into account the influence of the curvature of streamlines within the framework of the Rodi-Leshziner-Isaev approach, is used. At Reynolds number Re=104, the oscillation period of the transverse Rz and longitudinal forces Rx, as well as the total heat transfer Numm to the control section of the heated channel wall with a dimple, is set equal to 60, which corresponds to the Strouhal number St=0.0167. Computer visualization of swirling jet-vortex flows demonstrates focus-type sources on the side faces of the dimple. In the self-oscillating mode, a two-cell vortex system is formed with different intensities at the oscillation period Rz. Periodic changes in friction, Nusselt numbers and temperature are recorded in the longitudinal and transverse median sections of the dimple and reflect the oscillations of the vortex structure from left to right and from right to left. The formation of a fan jet is shown, which oscillates relative to the plane of longitudinal symmetry, causing a redistribution of power and thermal loads.

Multi-stage gas separation process for separation of carbon dioxide from methane: Modeling, simulation, and economic analysis

The emphasis of this study is the use and comparison of the rubbery and glassy membranes in the multi-stage gas separation process for separation of the CO2/CH4 mixtures. For analysis of the gas separation processes, reliable modeling and simulation of the process are essential. Thermodynamic models of lattice fluid (LF) and non-equilibrium lattice fluid (NELF) were used to model the gas sorption in the rubbery and glass membranes, respectively, and a transfer model was employed to model the gas diffusion. The developed model was integrated with the Aspen Custom Modeler (ACM) of Aspen Plus software to simulate various proposed gas separation processes. The performance of single-stage and multi-stage processes was evaluated in terms of the CH4 recovery, product purity, total capital investment, and total annual cost. It was found that the membranes with higher permeability had more suitable economic parameters than the membranes with high CO2/CH4 selectivity. The results showed that the CH4 recovery of 99% and product purity of 98% could not be achieved by the single-stage process. However, the desired separation criteria can be met via the multi-stage membrane processes with two or three membranes. The best configuration was chosen from different configurations by examining the economic parameters.

The role of apoptotic bone marrow cells in activation of liver regeneration

Objective: using an adoptive transfer model to study the cellular mechanisms involved in the formation of the initial stage of liver regeneration during intraperitoneal injection of a healthy recipient with apoptotic bone marrowderived mononuclear cells (BM-MNCs) from a donor after extended liver resection.Materials and methods. Male Wistar rats (n = 40) were used to create a model of adoptive transfer of apoptotic BM-MNCs (a-BM-MNCs) taken from the donor after extended liver resection to a healthy recipient. During the experiments, the animals were divided into five groups. Four experimental groups with intraperitoneal injection of the same doses to the recipient: freshly isolated BM-MNCs (group 1); BM-MNCs subjected to apoptosis for 48 hours by storage at t = 4–6 °C in phosphate-buffered saline (PBS) (group 2) or in a Custodiol HTK solution (group 3). In group 4, the animals were injected with PBS after storing BM-MNCs in it. The control animals were animals injected with saline (group 5). For selection of effective modes of apoptosis induction, BM-MNCs stained with 7AAD after incubation in solutions were analyzed by flow cytometry. Targeted transfer of regenerative signals to the recipient was assessed by the mitotic activity of hepatocytes in the liver and tubular epithelium in the kidneys, as well as by the intensity of microstructural changes in the liver 24, 48 and 72 hours after injection of the studied material.Results. BMC incubation in PBS and HTK for 48 hours at t = 4–6 °C provides the most effective accumulation of a-BM-MNCs in early apoptosis. It was shown that a-BM-MNCs retain the ability to target-focused transmission of regulatory signals to the liver supported by autophagy process during adoptive transfer. It was established that a-BM-MNCs (groups 2 and 3) in comparison to native BM-MNCs (group 1) at adoptive transfer increased the regenerative potential of the liver due to pronounced increase in the activity of autophagy processes and directed infiltration of immunomodulatory mononuclear cells in the liver.Conclusion. a-BM-MNCs create a stronger basis for development and implementation of a targeted and effective regeneration program by enhancing autophagy processes and immunomodulatory effect on mononuclear cells, which are regenerative signal carriers.

Digital Modeling of Heat Transfer during the Baking Process

Numerical modeling and analysis of the baking process are challenging biochemical processes occurring in bread. These changes result from mass engineering tasks, usually characterized by the complex chain of chemical, physical, and heat transfer processes impacting the baking at the same time primarily caused by a variation of two dominating factors: (i) the heat and (ii) the internal moisture content at different temperatures and during the time’s process. This study presents an analysis of the 1-D computational fluid dynamics model for simultaneous heat transfer within a cylindrical bread sample. The numerical simulations were performed using the finite difference model (FDM) and the finite element model (FEM). In the first case, the proposed numerical model considered radiation and convection during sample heating and described the sample’s simultaneous heat, water, and vapor diffusion mechanisms. The calculations indicated that the FDM was susceptible to the time step; consequently, the range of 10 s and 100 s yielded the only relevant results. In the second case, the FEM was used to describe the phenomena of transportation during baking. Results obtained by the FEM showed a large temperature gradient near the surface. The study showed the presence of some critical cases that are considered the most influential on the stages of bread production. The first critical value is the time when the baking temperature reaches 100° C. The second critical value is the time when the liquid water content in the baking medium reaches its peak. The boundary conditions were examined and illustrated by figures in the center and the surface of the bread.

Study on Customized Shuttle Transit Mode Responding to Spatiotemporal Inhomogeneous Demand in Super-Peak

Instantaneous mega-traffic flow has long been one of the major challenges in the management of mega-cities. It is difficult for the public transportation system to cope directly with transient mega-capacity flows, and the uneven spatiotemporal distribution of demand is the main cause. To this end, this paper proposed a customized shuttle bus transportation model based on the “boarding-transfer-alighting” framework, with the goal of minimizing operational costs and maximizing service quality to address mega-transit demand with uneven spatiotemporal distribution. The fleet application is constructed by a pickup and delivery problem with time window and transfer (PDPTWT) model, and a heuristic algorithm based on Tabu Search and ALNS is proposed to solve the large-scale computational problem. Numerical tests show that the proposed algorithm has the same accuracy as the commercial solution software, but has a higher speed. When the demand size is 10, the proposed algorithm can save 24,000 times of time. In addition, 6 reality-based cases are presented, and the results demonstrate that the designed option can save 9.93% of fleet cost, reduce 45.27% of vehicle waiting time, and 33.05% of passenger waiting time relative to other existing customized bus modes when encountering instantaneous passenger flows with time and space imbalance.

Experimental study of the nature of the 1− and 2− excited states in Be10 using the Be11(p,d) reaction in inverse kinematics

The nature of the 1− and 2− excited states in Be10 is studied using the Be11(p,d) transfer reaction in inverse kinematics at 10A MeV at TRIUMF ISAC-II, in particular to assess whether either of them can be considered as an excited halo state. The angular distributions for both states are extracted using deuteron-γ coincidences and analyzed using a transfer model taking into account one-step and two-step processes. A good fit of the angular distributions is obtained considering only the one-step process, whereby an inner p3/2 neutron of Be11 is removed, leaving the halo neutron intact. Higher-order processes however cannot be rejected. The small spectroscopic factors extracted suggest that the structure of both states is not uniquely halo-like, but rather display a more complex configuration mixing cluster and halo structures. Further insights are limited, as this experiment specifically probed the halo-like (but not cluster-like) Be11(1/2+)⊗(νp3/2)−1 configuration in both states.1 MoreReceived 7 May 2021Accepted 8 September 2021DOI:https://doi.org/10.1103/PhysRevC.104.044601©2021 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasSpectroscopic factors & electromagnetic momentsTransfer reactionsProperties6 ≤ A ≤ 19TechniquesRadioactive beamsNuclear Physics

4D-исследование вихревых движений жидкостей внутри глаза

The eye is a complex system of boundaries and fluids with different viscosities within the boundaries. At present, there are no experimental possibilities to thoroughly observe the dynamic 4D processes after one or another method of eye treatment is applied. The complexity of cumulative, i.e., focusing, and dissipative, i.e., scattering, convective and diffusion 4D fluxes of fluids in the eye requires 4D analytical and numerical models of fluid transfer in the human eyeball to be developed. The purpose of the study was to develop and then verify a numerical model of 4D cumulative-dissipative processes of fluid transfer in the eyeball. The study was the first to numerically evaluate the values of the characteristic time of the drug substance in the vitreous cavity until it is completely washed out, depending on the injection site; to visualize the paths of the vortex motion of the drug in the vitreous cavity; to determine the main parameters of the 4D fluid flows of the medicinal substance in the vitreous cavity, depending on the presence or absence of vitreous detachment from the wall of the posterior chamber of the eye. The results obtained are verified by the experimental data available to doctors. In the eye, as a partially open cumulative-dissipative system, Euler regions with high rates of cumulative flows and regions with low speeds or stagnant Lagrange flow zones are defined

Analysing the Contact Conduction Influence on the Heat Transfer Intensity in the Rectangular Steel Bars Bundle.

Bundles of steel bars, besides metal foams, are an example of cellular solids. Such bundles constitute a charge during the heat treatment of bars. The paper presents a mathematical model of transient heat transfer in a bundle of rectangular steel bars based on the energy balance method. The key element of this model is the procedure of determining the effective thermal conductivity using the electrical analogy. Different mechanisms of heat transfer occurring within the analysed medium (conduction in steel and contact conduction) are assigned corresponding thermal resistances. The discussed procedure involves expressing these resistances with the use of arithmetic relationships describing their changes in the temperature function. Thermal contact resistance has been described with the use of the relationships determined experimentally. As a result of the performed calculations, the influence of contact conduction between the adjacent bars and bundle arrangement on its heating time was established. The results of the calculations show that the heating time of bundles can be lowered by 5–40% as a result of a decrease in the thermal contact resistance. This effect depends on the bar size and bundle arrangement. From the practical point of view, the analysed problem is connected with the optimization of the heat treatment processes of steel bars.