Search

The research on the gas axial flow regulating valve is one of the key tasks for the localization of critical valves in natural gas pipelines. With the main purpose of improving the design of the sleeve of the gas axial flow regulating valve, numerical simulation calculations are conducted on the internal flow passage of the gas axial flow control valve by using fluid simulation software. According to the existing design of the valve sleeve, the design scheme of the valve sleeve is improved by changing the diameter of the throttle hole of the valve sleeve. After improving the valve sleeve, eight simulations have been performed at different openings to analyze the velocity field, pressure distribution, and variations in aerodynamic noise within the flow passage at two design schemes. A comparison is also made between two valves for their respective flow fields and noise characteristics which use two different sleeve designs. The simulation results indicate that appropriately increasing the throttle aperture can improve the flow performance of a gas axial flow regulating valve, reducing noise levels to below 100 dB at medium and small openings. [ABSTRACT FROM AUTHOR]

AbstractIn this paper, a semi-analytical elasto-plastic (SAEP) model is proposed to simulate wheel motion on soft soil using a Modified Cam Clay (MCC) constitutive model. The focus is on enhancing computational efficiency by integrating the MCC model into the framework. The MCC-based model outperforms the Drucker-Prager with Cap hardening (DPC)-based model in terms of reduced computation time, stability, and convergence. Simulations with a 30% slip ratio show a significant reduction in solution time compared to the DPC-based model. For slip ratios of 50% and 90%, the computation time decreases even further. Overall, the MCC-based model demonstrates over 100 times reduction in the solution time compared to the DPC-based model, particularly with high slip ratios. Indeed, the DPC-based model was found to be highly sensitive to high values of slip ratios, whereas the MCC-based model is not. In comparison with existing methods in the literature, the proposed formulation is superior in terms of significantly reduced solution time and improved numerical stability, making it ideal for advanced applications where fast solutions are crucial. [ABSTRACT FROM AUTHOR]

The Particle Image Velocity method was used to investigate the velocity fields when the liquid layer height changed from 0.6 to 5.1 mm. The loss of stability of the velocity field during local heating is realized at the Bond number (Bo) 0.01–0.02, which is 10–20 times lower than the critical value of Bo(cr) compared to heat exchange at a uniform wall temperature. The Marangoni flow depends both on the height and the layer diameter. The critical height of the layer 2–2.5 mm leads to a sharp change in the flow pattern. [ABSTRACT FROM AUTHOR]

Conical diffusers are widely used in technical devices (gasifiers, turbines, combustion chambers) and technological processes (ejectors, mixers, renewable energy). The perfection of flow gas dynamics in a conical diffuser affects the intensity of heat and mass transfer processes, the quality of mixing/separation of working media and the flow characteristics of technical devices. These parameters largely determine the efficiency and productivity of the final product. This article presents an analysis of experimental data on the gas-dynamic characteristics of stationary air flows in a vertical, conical, flat diffuser under different initial boundary conditions. An experimental setup was created, measuring instruments were selected, and an automated data collection system was developed. Basic data on the gas dynamics of air flows were obtained using the thermal anemometry method. Experimental data on instantaneous values of air flow velocity in a diffuser for initial velocities from 0.4 m/s to 2.22 m/s are presented. These data were the basis for calculating and obtaining velocity fields and turbulence intensity fields of the air flow in a vertical diffuser. It is shown that the value of the initial flow velocity at the diffuser inlet has a significant effect on the gas-dynamic characteristics. In addition, a spectral analysis of the change in air flow velocity both by height and along the diffuser axis was performed. The obtained data may be useful for refining engineering calculations, verifying mathematical models, searching for technical solutions and deepening knowledge about the features of gas dynamics of air flows in vertical diffusers. [ABSTRACT FROM AUTHOR]

According to GJB1179A-2012 "Quality Requirements for Low Speed and High Speed Wind Tunnel Flow Fields", the velocity field calibration is a key item in the wind tunnel flow field calibration and an important basis for evaluating whether wind tunnels have the ability to conduct model tests. Center line probe is a universal calibration instrument used for velocity field calibration in the subsonic and transonic wind tunnels. In order to reduce the disturbance of the center line probe on the flow field and generate an undisturbed flow field in the test section, it is generally required that the blockage degree should not exceed 0.5%, and the head cone is located in the contraction section of the wind tunnel. In recent years, with the construction of large-scale transonic wind tunnels of over 2 meters in China, traditional center line probe design schemes face certain difficulties in the manufacturing, installation and calibration. In response to this issue, the aerodynamic shape and installation position of the head of the center line probe is optimized, achieving the weakening of the intensity and disturbance range of the conical shock wave at the head of the probe, and exerting the wave attenuation ability of the acceleration zone in the test section. A non-interference flow field consistent with traditional long center line probe is generated in the test section, greatly shortening the length of the probe. The present study provides a feasible technical solution for the design of center line probe for velocity field calibration in large-scale transonic wind tunnels.

In the evaporation crystallization unit of wet flue gas desulfurization process, the medium inside the pipeline is mainly a liquid-solid two-phase fluid. Improper equipment layout and pipeline design can easily cause solid particle precipitation and deposition, resulting in certain erosion and wear on pipelines, elbows, etc. Starting from engineering practice, this article systematically reviews the layout and pipeline design of the main equipment of an evaporative crystallization system in a certain device. A fluid flow model ( CFD) is used to simulate and analyze the erosion of elbows with different curvature radii that affect the long-term operation of the device. The distribution of fluid velocity field, pressure distribution, particle motion path, and erosion rate inside the pipeline are studied. It is proved that using 3D, 6D and other curvature radius elbows can effectively reduce the erosion and wear of solid particles on the pipeline in the fluid, ensuring the long-term operation of the device. [ABSTRACT FROM AUTHOR]

Pneumatic spring dampers are extensively utilized within hydraulic systems, and the flow characteristics of the internal oil play a crucial role in determining noise and vibration levels. To validate the mechanical structure's reliability, the shock absorber was simplified and the fluid domain was extracted using a CFD method. The velocity field and pressure field under different conditions were then simulated and analyzed. A finite element model of the flow field was established, and its accuracy was verified by comparing simulation results of gas side pressure with experimental results. According to the working principle of the oil-gas spring, dynamic active surfaces in contact with the main piston and dynamic driven surfaces in contact with the floating piston were defined, determining moving conditions for dynamic grids. The results indicate that as the diameter of flow channels increases, there is a decrease in average pressure drop within the oil chamber (i.e., pressure loss within the flow field). Additionally, as bend angle increases, average pressure drop decreases. However, optimization effects become less significant beyond a certain bend angle [ABSTRACT FROM AUTHOR]

The local distributions of both the temperature and pressure have a great influence on the rheological characteristics of the drilling fluid, thereby affecting its flow law in a wellbore. Along these lines, in this work, the rheology of water-based drilling fluid samples under high-temperature (30°C–210°C) and high-pressure (34.5 MPa–172.4 MPa) (HTHP) conditions was systematically analyzed. The constitutive model of the variation of the apparent viscosity of the drilling fluid with the temperature and pressure was successfully established. The analysis revealed that, among the Bingham model, the Power law model, the Herschel-Bulkley (H-B) model, and the Casson model, the H-B model can accurately describe the rheology of the drilling fluid under HTHP conditions. Therefore, the H-B model was used to perform numerical simulations of the flow law of the water-based drilling fluid in the wellbore. The simulation results demonstrated that the drilling fluid viscosity decreased as the depth of the wellbore increased, and was mainly influenced by the temperature. The maximum viscosity inside the drill pipe was mainly concentrated in the middle region, and that of the fluid when flowing in the annulus was mainly concentrated on the side near the outer wall of the annulus. This work provides valuable insights for setting the key parameters of the drilling fluid and wellbore cleaning in the drilling operation of a 1×104 m deep well. [ABSTRACT FROM AUTHOR]

The blast furnace smelting of vanadium–titanium ore plays a crucial role in the efficient utilization of vanadium-titanium resources. In this research, a detailed numerical simulation study of the temperature, velocity, and concentration fields during the smelting process in a vanadium–titanium blast furnace was conducted. The actual production data from a 1750 m3 vanadium–titanium blast furnace was utilized, combined with softening and dripping parameters and material balance calculations, to develop a two-dimensional blast furnace model. This model was employed to analyze the effects of varying smelting intensities on the internal operating conditions of the furnace. The study found that as smelting intensity increased, significant changes occurred in the temperature fields and CO concentration fields within the furnace, thereby affecting the reduction efficiency of the burdens. Additionally, this research also shows that increasing the proportion of Baima pellets in the furnace will lead to the expansion of the soft melting zone and the upward movement of the soft melting zone. This investigation not only revealed the variations in the internal physical fields of the blast furnace under different operating conditions but also provided theoretical foundations and references for optimizing the design and operation of vanadium–titanium blast furnaces. By comparing the velocity field under different smelting intensities, it was found that the difference was small, which was mainly related to the expansion behavior of the pellets. These findings provide an important scientific basis for further improving the efficiency of blast furnace smelting and reducing costs. [ABSTRACT FROM AUTHOR]

In this research, the deformation pattern of Alborz is investigated using a combination of data from the new permanent GPS networks that belong to State Organization for Registration of Deeds and Properties (SHAMIM) and Tehran Municipality (SAMT), the new temporary IASBS_NCC network and the permanent and temporary stations of the National Cartographic Organization. The addition of the 27 new GPS stations has improved the obtained velocity field, which shows that the active deformation happens across the entire width of Alborz from south to north by several faults and active fault zones. Contrary to the common belief about the strain partitioning in the Alborz Mountains between the strike-slip faults in the southern flank of the Alborz and along the compressional south-dipping Khazar fault in the northern flank of the Alborz, the new velocity field indicates a spread of strike-slip and compressional movements along different faults across the width of the Alborz. In previous works, due to the lack of GPS stations between the Khazar fault and other active faults in the northern flank of the Alborz (e.g. North Alborz fault), all the observed deformation in the northern flank of the Alborz has been associated with the Khazar fault. In the improved velocity field, the presence of a new GPS vector between the North Alborz and the Khazar fault in the eastern part of the Alborz indicates a dominant role of the North Alborz fault in the strain accommodation once compared to the Khazar fault. Like the previous works, the new velocity field shows a lower total strain for the western Alborz, which is consistent with the lower observed seismicity in the western Alborz. The new velocity field indicates an active extensional system in the western Alborz in a longitude range of 49o to 50.5o around the Tarom Valley. The extensional system might be related to the counterclock wise rotation of the South Caspian Basin relative to Eurasia. The improved velocity field shows a noticeable strike-slip motion of 2 mm/yr at the northern edge of Central Iran which could be related to the Aran-Torud fault zone and Attari fault. There is also a shortening rate of ~2 mm/yr between the northern edge of Central Iran and the Eastern Alborz which could be related to the salt tectonic within the Great Kavir fault. The improved velocity field shows a right-lateral strike-slip motion of ~1 mm/yr across the Indes and Kushk-Nosrat faults. Despite the observed large seismic activity and a geological slip rate of 2 mm/yr for the eastern part of the Mosha fault, both strike-slip and compressional slip rates along the Mosha fault are less than 1 mm/yr. Within a radius of ~50 km from the center of Tehran metropolitan area, there is no noticeable rate of strike-slip or compressional movement and the strain rate is around the error limit or less than 1 mm/yr. The low strain rate implies a very long earthquake return period for large earthquakes in Tehran metropolitan area. [ABSTRACT FROM AUTHOR]

(Objective) Improved cold chain transportation equipment and analyzed the impact of active and passive dual modes on the environmental distribution characteristics inside cold chain containers. (Methods) An active and passive dual-mode refrigerated container (temperature control range is --1-10 °C) was proposed, which integrated refrigeration unit, fiber air supply pipe and phase-change cold storage plate. The system operated in passive cooling mode, and switched to active cooling mode when the air temperature inside the box was greater than 10 °C. (Results) The results showed that the velocity distribution in the active and passive dual mode box was uniform, and the air flow could reach all parts of the box. The temperature distribution in the active release mode was uniform, the temperature gradient in the box was small, and the maximum temperature difference was only 0.3 °C. The temperature gradient in the passive release mode was slightly larger and the temperature non-uniformity was higher than the active release mode. Compared with the passive refrigeration mode alone, the active and passive dual mode could effectively ensure the long-term transportation of the temperature zone below 10 °C, which was conducive to the refrigerated transportation of most fresh goods. (Conclusion) The design of active and passive dual-mode cold chain container has great potential for energy optimization, uniform flow field, stable temperature and strong practical value. [ABSTRACT FROM AUTHOR]

This study investigates the hydrodynamic behavior and mass transfer performance in water electrolysis within an alkaline solution (30% wt KOH). By using a glass electrolyzer with vertical stainless steel 304 electrodes spaced 20 mm apart, the research employs an optical flow method to analyze the velocity field of hydrogen bubbles. Image sequences captured by a CCD camera with a pixel resolution of 67.2 μm facilitate this analysis. The study focuses on the effect of current density, ranging from 33 to 650 A/m2. Experimental results demonstrate that the velocity distribution in most areas of the electrolyzer is primarily influenced by two asymmetric flow patterns caused by the buoyancy of hydrogen and oxygen bubble layers. Regions with lower depths exhibit increased velocity and vorticity fields, resulting in greater motion within the electrolyte. Conversely, at higher current densities, the average velocity decreases due to the expansion of dynamic areas. These complex flow structures significantly affect bubble dynamics, causing velocity fluctuations between the electrodes. The findings offer valuable insights into hydrogen bubbles' dynamics and transport phenomena within the electrolyzer, enhancing the understanding of bubble behavior in alkaline water electrolysis. • Hydrogen generation in electrolysis has been experimentally studied. • Experimental analysis of the velocity field and main characteristics of the flow field. • Velocity fluctuations and recirculation occur in electrolyte regions, influencing bubble dispersion and dynamics. • Current density significantly impacts bubble generation, dispersion, and dynamics. [ABSTRACT FROM AUTHOR]

The author has presented results of numerical modeling of the influence of the angle of attack of a thin width-limited plate with a short chord on the velocity field of the internal region of a turbulent boundary layer (TBL) and skin friction. The computations were performed by the large eddy simulation (LES) method at the Reynolds number Reθ = 540 calculated from the velocity on the channel axis and the momentum thickness. Changes in the average and pulsation characteristics of the three-dimensional velocity field under the impact of the wake of the plate and of tip vortices as functions of the angle of attack of the plate in the range ±1° have been analyzed. It has been shown that a determining influence on the formation of the velocity field is exerted by the tip vortices whose vorticity is opposite with the positive and negative angles of attack. The mean value of the skin-friction coefficient decreases by 6% at the positive angle of attack and by 14% at the negative angle with respect to the value of this coefficient in an unperturbed TBL. [ABSTRACT FROM AUTHOR]

The investigation of the couple stress fluid flow behaviour between two parallel plates under sudden stoppage of the pressure gradient is considered. Initially, a flow of couple stress fluid is developed between the two parallel plates under a constant pressure gradient. Suddenly, the applied pressure gradient is stopped, and the resulting unsteady flow is studied. This type of flow is known as run-up flow in the literature. Now the flow is expected to come to rest in a long time. Usually, these types of problems are solved by using the Laplace transform technique. There are difficulties in obtaining the inverse Laplace transform; hence, many researchers adopt numerical inversions of Laplace transforms. In this paper, the problem is solved by using the separation of variables method. This method is easier than the transform method. The velocity field is analytically obtained by applying the usual no-slip condition and hyper-stick conditions on the plates, and hence the volumetric flow rate is derived at subsequent times. The steady state solution before the withdrawal of the pressure gradient is matched with the initial condition on time. The rest time, i.e. the time taken by the fluid to come to rest after the pressure gradient is withdrawn is calculated. The graphs for the velocity field at different times and different couple stress parameters are drawn. In the special case when a couple stress parameter approaches infinity, couple stress fluid becomes a viscous fluid. Our results are in good agreement with this special case. [ABSTRACT FROM AUTHOR]

This study explores the use of natural convection heating in mobile homes by embedding panels in the walls that utilize hot water to supply thermal energy. It implemented natural convection heating with the thermal energy supplied by hot water by embedding natural convection panels in the walls of a natural convection heating system for mobile homes. The size of the natural convection heating system for mobile homes is 1800 mm wide, 1100 mm long, and 2100 mm high. The results of three-dimensional temperature and velocity fields inside the mobile home in this study showed uniform three-dimensional temperature and velocity fields resulting from the natural convection heat transfer inside the mobile home, and the temperature fields were shown to be well-being temperature fields beneficial to health. It was verified that heating is achieved by natural convection heat transfer, which is beneficial to health. In mobile home heating, the experimental natural convection heat transfer value and the theoretical natural convection heat transfer value of the air for heating matched relatively well in the entire range of the experiment. In addition, as the mass flow rate of hot water increased, the air temperature inside the mobile home rose. Therefore, as the hot water flow rate increased, the heating performance of the mobile home improved. [ABSTRACT FROM AUTHOR]

Copyright of Chemical Engineering (China) / Huaxue Gongcheng is the property of Hualu Engineering Science & Technology Co Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Velocity fields measured in the vicinity of the perforated leading edge of a turbine nozzle vane using the particle image visualization technique are presented. Noncontact measurements were performed in a plane segment consisting of three nozzle vanes and having an optically transparent inlet section offering visual access to the region of the leading edge of the central vane for a high-speed camera and to the laser sheet. The experimental investigations were performed at a fixed incoming flow velocity of 33 m/s, and the relative air flowrate through the cooling holes varied from 1.6 to 6.4%. The cooling film flow near the leading edge was visualized for three models of vanes differing in the air supply method to the holes, hole diameter, and number. Supply of the coolant to the cooling holes from one cavity resulted in a high degree of nonuniformity in the distribution of the film over the leading edge, which was caused by a high blowing ratio for the jets injected through holes located closer to the suction side. The experimental results have revealed that separate supply of cooling air to the holes on the pressure side, leading edge, and suction size minimizes sensitivity of the formed film thickness to the relative flow rate of the coolant and provides a more uniform distribution of the coolant over the vane surface in a wide range of the blowing ratio for the jets that varies from 0.5 to 2.5. Visualization has demonstrated extensive unsteadiness of the film flow along the vane airfoil. In this case, the cooling jet fed through the central hole oscillates, thereby leading to periodic formation of a film on either the pressure side or the suction side. [ABSTRACT FROM AUTHOR]

The cap geometry and formation mechanism play a key role in influencing the hole-making quality on the bore exit side and must be the focus of research in orbital drilling of aeronautical metal materials. For a "bowl shape" cap geometry formed in orbital drilling process, the corresponding undeformed cap periphery geometry, generated by the cap periphery cutting edges, is simulated and given the parametric description. Especially, the cap periphery is simplified as a simply supported annular plate under uniform load with arbitrary loading radius based on the characteristics of the cap periphery shape and mechanical analysis of processing. Then its unified plastic limit analysis is developed. The ultimate load, stress field, and plastic deformation at the periphery of the cap are derived from the unified strength theory. Furthermore, the numerical solutions are obtained in terms of the Tresca yield, Huber–von Mises, and twin-shear yield criteria. The conclusions enabled an in-depth understanding of the cap periphery formation mechanism in the orbital drilling of holes from the unified plastic limit analysis perspective. [ABSTRACT FROM AUTHOR]

In quasi-two-dimensional conditions, different invasion patterns can be observed when a fluid displaces another fluid with a higher viscosity. The transition from interfacial instability to fracture during gas invasion remained poorly understood, and classification criteria for different invasion patterns demanded further improvement. In this study, single-point compressed gas injection experiments were conducted in magnesium lithium phyllosilicate (MLPS) suspensions in a rectangular Hele-Shaw cell. Interestingly, with the increase of the injection pressure and the decrease of the concentration of MLPS suspension, the gas invasion pattern underwent a transition from viscous elastic fracture, elastic fracture, elastic viscous fingering to viscous fingering, in which viscous elastic fracture was observed for the first times. We detailly discuss the characteristics and occurrence conditions of each invasion pattern. Furthermore, by analyzing the velocity field of each invasion pattern, it is found that the relationship between the velocity direction around the gas and the gas growth direction varies with different invasion patterns. A simple and effective quantitative indicator is constructed to distinguish the different invasion patterns. Following the identification of invasion patterns, a further investigation was conducted into the relationship between invasion patterns and experimental conditions. By utilizing the relationships among injection conditions and material rheological properties, two dimensionless numbers, Bingham number and Weissenberg number, are conducted, which have an impact on the various invasion patterns and invasion process. A unified phase diagram based on the Bingham number and Weissenberg number was also proposed to incorporate the possible gas invasion patterns in the MLPS suspension. [ABSTRACT FROM AUTHOR]

We present average ground‐surface velocities and strain rates for the 1.7 million km2 area of Iran, from the joint inversion of InSAR‐derived displacements and GNSS data. We generate interferograms from 7 years of Sentinel‐1 radar acquisitions, correct for tropospheric noise using the GACOS system, estimate average velocities using LiCSBAS time‐series analysis, tie this into a Eurasia‐fixed reference frame, and perform a decomposition to estimate East and Vertical velocities at 500 m spacing. Our InSAR‐GNSS velocity fields reveal predominantly diffuse crustal deformation, with localized interseismic strain accumulation along the North Tabriz, Main Kopet Dagh, Main Recent, Sharoud, and Doruneh faults. We observe signals associated with recent groundwater subsidence, co‐ and postseismic deformation, active salt diaprism, and sediment motion. We derive high‐resolution strain rate estimates on a country‐ and fault‐scale, and discuss the difficulties of mapping diffuse strain rates in areas with abundant non‐tectonic and anthropogenic signals. Plain Language Summary: Across the entire country of Iran, the ongoing convergence of the Arabian and Eurasian tectonic plates at about two cm every year is deforming the Earth's crust, producing earthquakes in this process of continental collision. Accurate measurements of how the ground is moving today are critical to understanding both the county‐scale deformation, and the local‐scale earthquake hazard, where the crust is deforming quickly and building up strain that is likely to be released in future major earthquakes. We combine multiple series of satellite radar images with GPS velocities to estimate East and vertical ground motion across all of Iran, at a higher level of detail than previous GPS‐only studies have been able to capture. Our velocity fields show a complex mix of ground motion signals, from crustal deformation on a country‐scale, to rapid land subsidence caused by the extraction of groundwater from aquifers. Some of the major faults are clearly building up strain for future earthquakes, but other regions are deforming much more diffusely, making it difficult to ascertain the locations of any future seismic hazard and ground shaking. Key Points: We generate high‐resolution East and vertical velocity fields for Iran using Sentinel‐1 InSAR and GNSS observationsRegional deformation is diffuse, with interseismic strain localized onto the Doruneh, Main Kopet Dagh, North Tabriz, and Sharoud faultsIran contains a wealth of time‐varying, short‐wavelength signals associated with groundwater extraction, salt diaprism, and sediment motion [ABSTRACT FROM AUTHOR]

Copyright of Journal of Geodesy & Geodynamics (1671-5942) is the property of Editorial Board Journal of Geodesy & Geodynamics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Robot-assisted rehabilitation is a crucial approach to restoring motor function in the limb. However, the current training trajectory lacks sufficient theoretical or practical support, and the monotony of single-mode training is a concern. Tai Chi Pushing Hands, a beneficial and effective daily exercise, has been shown to improve balance function, psychological state, and motor function of the upper extremities in patients recovering from stroke. To address these issues, we propose a new active rehabilitation training that incorporates Tai Chi Pushing Hands movements and yin-yang balance principles. The training trajectory and direction are encoded by the velocity field and consist of two processes: yang (push) and yin (return). During yang, the limb actively pushes the robot to move, while during yin, the limb actively follows the robot’s movement. To provide necessary assistance, an admittance controller with self-adaptive parameters is designed. In addition, we introduce two indexes, the ‘Intention Angle’ (ϖ) and the time ratio (Γ), to evaluate motion perception performance. Our experiment was conducted on a 4-degree-of-freedom upper limb rehabilitation robot platform, and the subjects were separated into a familiar group and an unfamiliar group. The experiment results show that the training could be completed well no matter whether the subject is familiar with Tai Chi Pushing Hands or not. The parameters and the movement of the robot can be adjusted based on the interactive force to adapt to the ability of the subject.

The virus transmission chain of Covid-19 has a resulted in a significant, global impact on social and working life. Covid-19 vaccines require protective refrigerated conditions during delivery and storage. Warehousing and transportation of these vaccines need to be properly controlled to maintain the product quality and efficacy. Logistics companies developed large-scale refrigerated warehouses as storage relay stations. The heat convection between two rooms of the large-scale, low-temperature warehouses with different temperatures for example (5 °C, -15 °C) should be prevented to improve efficiency. In this study, an innovative flow isolation device (FID) was designed in Taipei Tech to block the storage areas, preventing heat convection. This device can maintain a constant low-temperature in warehouses used for vaccine storage. The axial flow fan draws air from the protected zones (5 °C, -15 °C) into the device. A perforated plate stabilizes the flow rate and maintains a uniform flow direction, creating a flow barrier created between two rooms. This flow can significantly block the heat convection induced by two warehouses with different temperatures. The computational fluid dynamics (CFD) software Ansys Fluent is used to simulate the effect of the FID on the prevention of the heat convection between two rooms. Different case studies were simulated at different machine sizes and supply air flow speeds. The simulated flow patterns and velocity fields are used to evaluate the highest isolation efficiency. The findings show that the FID device can effectively maintain the low temperature of the warehouse. Moreover, the FID helps to avoid heat loss and maintain thermal comfort in working areas, reducing the risk of hypothermia.

The paper considers the problems of macroparameter control in a linear dynamic system. In the authors’ previous paper, such problems in controlling nonlinear systems were investigated. Variations of the considered functionals and necessary optimality conditions were obtained. This paper focuses on the trajectory beam control in the linear case. In this case, the problem of beam control can be reduced to the problem of the individual trajectory control. The developed approach may be of interest in the study of charged particle dynamics in accelerating and focusing structures, as well as in the construction of the velocity field in automatic image processing.

Conical diffusers are widely used in technical devices (gasifiers, turbines, combustion chambers) and technological processes (ejectors, mixers, renewable energy). The perfection of flow gas dynamics in a conical diffuser affects the intensity of heat and mass transfer processes, the quality of mixing/separation of working media and the flow characteristics of technical devices. These parameters largely determine the efficiency and productivity of the final product. This article presents an analysis of experimental data on the gas-dynamic characteristics of stationary air flows in a vertical, conical, flat diffuser under different initial boundary conditions. An experimental setup was created, measuring instruments were selected, and an automated data collection system was developed. Basic data on the gas dynamics of air flows were obtained using the thermal anemometry method. Experimental data on instantaneous values of air flow velocity in a diffuser for initial velocities from 0.4 m/s to 2.22 m/s are presented. These data were the basis for calculating and obtaining velocity fields and turbulence intensity fields of the air flow in a vertical diffuser. It is shown that the value of the initial flow velocity at the diffuser inlet has a significant effect on the gas-dynamic characteristics. In addition, a spectral analysis of the change in air flow velocity both by height and along the diffuser axis was performed. The obtained data may be useful for refining engineering calculations, verifying mathematical models, searching for technical solutions and deepening knowledge about the features of gas dynamics of air flows in vertical diffusers.

The nature of a new isoscalar octupole resonance found within a kinetic model based on the Vlasov equation for finite Fermi systems with moving surfaces is studied. It is shown that this octupole resonance is due to dynamic effects of the nuclear surface, like the low-energy isoscalar dipole resonance (vortex dipole mode) observed in heavy nuclei. It is found that the velocity field associated with the new octupole resonance has a vortex character in the surface region of the nuclear liquid and, moreover, the vortex motion of nucleons is fragmented into three areas near the nuclear surface. At the same time, the velocity field associated with the high-energy octupole resonance found within our kinetic model displays an octupole deformation form and includes a compression within the nuclear fluid, which is consistent with the corresponding quantum calculations in the random phase approximation. [ABSTRACT FROM AUTHOR]

The Earth's crust is exposed by tectonic processes and is not static over time. Modelling of the Earth's surface velocities is of utmost importance for research in geodesy, geophysics, structural geology, and other geosciences. It may support positioning, navigation, seismic risk, and volcano notification services, for example. Space geodetic techniques can be used to provide high-quality velocities in a network of geodetic sites. Velocity field modelling should, however, expand the velocities from a discrete set of points to any location in-between. This paper presents four new methods for the Earth's surface velocity interpolation. Contrary to the widely used approach dividing the velocity field to the horizontal and vertical components, a full 3D interpolation approach is proposed based on the Delaunay triangulation and the n-simplex interpolation. The use of a combination of all three components is advantageous for geophysical interpretation. The proposed interpolation approach is entirely local but enables global modelling, which does not suffer from map projection distortions and singularities at the poles. Various global and regional position/velocity datasets are used to evaluate the performance of the proposed velocity interpolation methods. The latter provide practically the same results when applied to regional velocity field modelling. However, the so-called continuous piecewise quasi-radial 3D velocity field interpolation method is recommended for its favourable properties. It introduces an ellipsoidal Earth model, appropriately considers vertical/up and horizontal velocity components, tends to radial symmetry, and provides continuity for the interpolated velocity components as well as for the estimated uncertainties. [ABSTRACT FROM AUTHOR]

In order to solve the problem of uneven distribution of air conditioning temperature and air velocity in the ward, it is easy to produce the uncomfortable feeling of cold and hot and wind blowing. Taking the standard double room general ward of a newly built hospital as the research object, a mathematical model was established, and CFD software was used to numerically simulate the temperature field and velocity field of the air in the ward, optimize the location of the air outlet, and put forward the suggestion of the optimal installation location of the hospital bed. The results show that when the fan coiler air supply outlet is close to the west wall and the fresh air outlet is far away from the west wall, the inhomogeneity of the distribution of the temperature field and velocity field in the ward is reduced, and at this time, the temperature and velocity distribution of the air in the ward is more uniform, so that the patients' overall feeling in the ward is more comfortable, and at this time, the installation position of the air outlet is more reasonable; and it is determined that the optimal placement of the beds in the room is at the locations of x = 2 m, y = 2.5 m and x = 2 m, y = 4.5 m, and at this time the two beds are at the same time, which is more reasonable. When y = 4.5 m, the temperature difference between the two beds is less than 0.5 K, the wind speed difference is not more than 0.08 m/s, and the velocity gradient direction is the same. [ABSTRACT FROM AUTHOR]

In this article, we address the problem of estimating fluid flows between two adjacent images containing fluid and non-fluid objects. Typically, traditional optical flow estimation methods lack accuracy, because of the highly deformable nature of fluid, the lack of definitive features, and the motion differences between fluid and non-fluid objects. Our approach captures fluid motions using an affine motion model for each small patch of an image. To obtain robust patch matches, we propose a best-buddies similarity-based method to address the lack of definitive features but many similar features in fluid phenomena. A dense set of affine motion models was then obtained by performing nearest-neighbor interpolation. Finally, dense fluid flow was recovered by applying the affine transformation to each patch and was improved by minimizing a variational energy function. Our method was validated using different types of fluid images. Experimental results show that the proposed method achieves the best performance. [ABSTRACT FROM AUTHOR]

The realization of online prediction in rolling production line is an innovative breakthrough in key rolling technology. The deformation behavior of metal clad plate in the deformation zone under different roll diameters is modeled and analyzed in this paper based on the flow function method. The volume flow through the unit section at the rolling inlet is maximum. The maximum volume flow of carbon steel layer occurs at the near bonding surface. The maximum volume flow of stainless steel layer occurs near the top surface. The strong shear effect caused by the velocity break mainly occurs on the side of the carbon steel layer, which plays a decisive role in the composite of metal plate. Meanwhile, the position of the maximum shear stress has a tendency to move towards the outlet of the deformation zone with the increase of the reduction rate, contained within the rolling zone. According to the flow function field, the velocity field model of the clad plate in the rolling deformation zone is established. Based on the upper bound method, the layer thickness and every power proportion can be obtained by the principle of minimum energy. Further, the equivalent strain model of the element is established based on the velocity field and strain rate field models. The accuracy of the model is verified by rolling simulation, experiments and microscopic characterization under different working conditions. The model can provide theoretical guidance and technical support for the online prediction and control of deformation behavior in the rolling process.

This paper deals with problems of program control of a trajectory beam. We investigate formulations that arise when considering problems of charged particle beams control, as well as, for example, in image processing. In applied problems, it is often necessary to investigate the problem of the gravity center control of some set or changing the density distribution of particles according to some given one. The functionals proposed in the paper can be effectively used for the velocity field constructing in various image processing, in particular, medical diagnostic images. In this paper, the problem of constructing a velocity field is considered as a control and optimization problem, and, unlike the previous works of the authors, macroparameters characterizing the objects under study are used in optimization. In the article, variations of the studied functionals are obtained and the necessary optimality conditions are given.

Accurate prediction of deformation behavior of metal plate in deformation zone is the key point for rolling cladding process. At present, there is a lack of accurate analytical model about the deformation of metal plate in deformation zone. Therefore, an analytical model of the deformation characteristics in deformation zone for the two-layered metal clad plate produced by asymmetric rolling is established according to the practical requirements. Firstly, the stream function field model of the clad plate in the deformation zone is founded by using the stream function method. Based on the stream function field, the velocity field model of the clad plate in the deformation zone is established, and the precision of the velocity field model is demonstrated by the comparison between the finite element and the model analytical results. Based on upper bound theory, the layer thickness of the clad plate after rolling and the ratio of deformation power, friction power and shear power to the total power were calculated by minimizing the total rolling power. Finally, based on the thickness of clad plate after rolling and velocity field model, an analytical model is established to calculate the equivalent strain of the clad plate in the deformation zone. The accuracy of the analytical model is tested by the rolling cladding experiments and the finite element simulations. The results indicate that the analytical model has high precision and which makes it useful to predict the deformation behavior in the clad plate rolling process.

Copyright of Journal of Chongqing University of Technology (Natural Science) is the property of Chongqing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper presents the algorithms and results of calculations of the dynamics of a surface layer of a fluid under the action of currents that have emerged from a depth. Several approaches to model the velocity field in a horizontal flow round a fixed underwater obstacle are investigated. Formulas for calculating the velocity field on the free surface of an ideal homogeneous fluid are proposed. A computer program is developed that makes it possible to simulate the interaction of a stratified fluid flow with an underwater obstacle. The possibility of using asymptotic formulas for the far-field approximation to calculate the velocity field in a uniformly stratified fluid is studied. [ABSTRACT FROM AUTHOR]

The asymmetric phenomenon of the rolling process will cause rolling clad plate bending, and the inability to quantify accurately the bending curvature will reduce production efficiency and increase production costs in industrial production. Therefore, this paper establishes a curvature theoretical model of double-layer metal on the basis of the stream function method, which has high accuracy and can be used for predicting the plate curvature after asynchronous rolling. The stream function field, velocity field, and strain rate field model are established based on the geometric relationship of the rolling deformation zone. The total power model is represented by the five-node Gauss quadrature algorithm according to the complex forming process, and then, the real kinematic parameters are obtained by optimizing the total power. The theoretical model of plate curvature caused by linear strain difference and shear strain difference is calculated based on the kinematic parameters optimized from the total power in the final. This paper creatively proposes a method of integrating the positive strain rate and shear strain rate with time to obtain the strain after rolling, which avoids the error caused by the slab method linearizing the non-uniform distribution of shear stress along the vertical, and the nonlinear problems caused by yield criterion in solving the compressive stress. The article analyzes the accuracy of the velocity model and obtains the variation law of total power with reduction ratio and the variation law of curvature with velocity ratio and layer thickness ratio, and some methods to reduce outlet curvature are also proposed. The maximum, minimum, and average relative errors are 12.02%, 0.66%, and 4.95% by comparing theoretical results with experiments, which verifies the accuracy of the analytic model. The calculating time is less than 5 s, which is of great significance for the setting and optimization of rolling process parameters and online prediction. [ABSTRACT FROM AUTHOR]

The centrally symmetric problem of determining the velocity field in a continuous elastoplastic medium during a camouflet explosion has been solved assuming that the motion is non-oscillatory nature and that the medium in the plastic and elastic regions is incompressible. The solution was found using the camouflet equation — the relation for determining the pressure on the contact surface of the expanding explosion cavity. The solution can be used to estimate the dimensions of the expansion and plastic deformation regions and the impact of explosive disturbances on objects. [ABSTRACT FROM AUTHOR]

Copyright of Journal of China University of Petroleum is the property of China University of Petroleum and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The calculations of thermohydrodynamic parameters using a mathematical model of a plane swirling flow are compared with experimental data obtained in a vortex chamber and a Ranque vortex tube. It is shown that the proposed generalized solution is in good agreement with experiment and describes a stable flow core in the plane of the vortex cross section. In terms of application, the proposed solution can serve as the basis for engineering methods for the preliminary calculation of vortex apparatuses. [ABSTRACT FROM AUTHOR]