Interchange Flow Research Articles

Interchange flow control with dynamic obstacles optimized using genetic algorithms—a concept of virtual walls

Interchange flow control with dynamic obstacles optimized using genetic algorithms—a concept of virtual walls

Advancements in Adult and Neonatal Breathing Simulation Using the xPULMTM Electro-mechanical Lung Simulator

Abstract Simulation is essential for healthcare professionals, students, and researchers, providing a safe environment for skill development and improved patient care. This paper presents enhancements to the xPULMTMelectro-mechanical lung simulator, enabling simulation of adult and neonatal breathing patterns. Hardware improvements include interchangeable flow sensors and additional temperature, humidity, volatile organic compounds (VOCs), and pressure sensors. The software redesign separates control and processing elements, enhancing performance. Measured parameters demonstrate expanded capabilities, such as increased airflow range and higher sampling frequency. Airtightness measurements show improved chamber sealing. Future developments aim to simulate neonatal breathing patterns and optimise software for high-frequency measurements. The enhanced xPULMTM simulator provides a realistic platform for simulating lung mechanics, benefiting respiratory medicine research and education.

Generation and Evolution of Two Opposite Types of Mesoscale Plasma Sheet Bubbles

AbstractPrevious observations showed that there are two major types of mesoscale plasma sheet bubbles (plasma with relatively lower total entropy than ambient plasma): the type‐1 has density lower and temperature higher than ambient plasma, and the type‐2 has the opposite differences. We first show, from statistical analysis of observations, that both the type‐1 and type‐2 bubbles can be possibly generated locally by magnetic reconnection in the magnetotail. We then conduct simulations based on the Rice Convection Model to show that the density and temperature characteristics of a bubble can affect the bubble's evolution and associated magnetic field and flow perturbations through magnetic drift and precipitation. For both types, the bubble extends azimuthally as it moves inward, and Bz is enhanced near the bubble's earthward front. The flow perturbations within the bubble consist of two interchange flow vortices with a fast earthward‐flow channel near the center and return flows on the two sides. The low entropy of a bubble is contributed by the reduction in the higher energy ions in the type‐2 bubble but in the lower energy ions in the type‐1 bubble. Duskward magnetic drift of the bubble's depleted high‐energy ions allows the type‐2 bubble and the Bz enhancement to expand azimuthally wider toward dusk than does the type‐1 bubble. The electrons within the type‐2 bubble produce weaker ionospheric conductance, in particular on the dawnside of the bubble because these electrons drift toward dawn, which results in stronger flows within the dawnside flow vortex, as compared to the type‐1 bubble.

BioSCOOP - Biobank Sample Communication Protocol. New approach for the transfer of information between biobanks.

Dynamic development of biobanking industry (both business and science) resulted in an increased number of IT systems for samples and data management. The most difficult and complicated case for the biobanking community was cooperation between institutions, equipped with different IT systems, in the field of scientific research, mainly data interchange and information flow. Tools available on the market relate mainly to the biobank or collection level. Efficient and universal protocols including the detailed information about the donor and the sample are still very limited. Here, we have developed BioSCOOP, a communication protocol in the form of a well documented JSON API. The main aim of this study was to harmonize and standardize the rules of communication between biobanks on the level of information about the donor together with information about the sample. The purpose was to create a communication protocol for two applications: to transfer the information between different biobanks and to allow the searching and presentation of the sample and data sets.

Profit maximization of hybrid system under availability based tariff in deregulated environment

This paper proposes an idea for the profit maximization of hybrid system. Wind plant and pumped storage hydro plant acts as a hybrid system. Profit calculation is mainly based on frequency. Contract is signed between hybrid system and grid. Deviations from contract make unscheduled interchange flow between hybrid system and grid. Load scheduling is implemented in the utility connected load to maximize their profit and to minimize unscheduled interchange flow. The effect of load scheduling on the profit of hybrid system for different wind power is analyzed and compared with the case without load scheduling.

Uncertainty analysis of gas flow measurements using clearance-sealed piston provers in the range from 0.0012 g min−1 to 60 g min−1

This paper deals with an uncertainty analysis of gas flow measurements using a compact, high-speed, clearance-sealed realization of a piston prover. A detailed methodology for the uncertainty analysis, covering the components due to the gas density, dimensional and time measurements, the leakage flow, the density correction factor and the repeatability, is presented. The paper also deals with the selection of the isothermal and adiabatic measurement models, the treatment of the leakage flow and discusses the need for averaging multiple consecutive readings of the piston prover. The analysis is prepared for the flow range (50 000:1) covered by the three interchangeable flow cells. The results show that using the adiabatic measurement model and averaging the multiple readings, the estimated expanded measurement uncertainty of the gas mass flow rate is less than 0.15% in the flow range above 0.012 g min−1, whereas it increases for lower mass flow rates due to the leakage flow related effects. At the upper end of the measuring range, using the adiabatic instead of the isothermal measurement model, as well as averaging multiple readings, proves important.

Scenario-based stochastic optimal operation of wind, photovoltaic, pump-storage hybrid system in frequency- based pricing

This paper proposes the operating strategy of a micro grid connected wind farm, photovoltaic and pump-storage hybrid system. The strategy consists of two stages. In the first stage, the optimal hourly contractual agreement is determined. The second stage corresponds to maximizing its profit by adapting energy management strategy of wind and photovoltaic in coordination with optimum operating schedule of storage device under frequency based pricing for a day ahead electricity market. The pump-storage hydro plant is utilized to minimize unscheduled interchange flow and maximize the system benefit by participating in frequency control based on energy price. Because of uncertainties in power generation of renewable sources and market prices, generation scheduling is modeled by a stochastic optimization problem. Uncertainties of parameters are modeled by scenario generation and scenario reduction method. A powerful optimization algorithm is proposed using by General Algebraic Modeling System (GAMS)/CPLEX. In order to verify the efficiency of the method, the algorithm is applied to various scenarios with different wind and photovoltaic power productions in a day ahead electricity market. The numerical results demonstrate the effectiveness of the proposed approach.

Vulnerability Analysis of Urban Rail Transit Networks: A Case Study of Shanghai, China

Rail transit is developing rapidly in major cities of China and has become a key component of urban transport. Nevertheless, the security and reliability in operation are significant issues that cannot be neglected. In this paper, the network and station vulnerabilities of the urban rail transit system were analyzed based on complex network and graph theories. A vulnerability evaluation model was proposed by accounting metro interchange and passenger flow and further validated by a case study of Shanghai Metro with full-scale network and real-world traffic data. It is identified that the urban rail transit network is rather robust to random attacks, but is vulnerable to the largest degree node-based attacks and the highest betweenness node-based attacks. Metro stations with a large node degree are more important in maintaining the network size, while stations with a high node betweenness are critical to network efficiency and origin-destination (OD) connectivity. The most crucial stations in maintaining network serviceability do not necessarily have the highest passenger throughput or the largest structural connectivity. A comprehensive evaluation model as proposed is therefore essential to assess station vulnerability, so that attention can be placed on appropriate nodes within the metro system. The findings of this research are of both theoretical and practical significance for urban rail transit network design and performance evaluation.

Io torus plasma transport under interchange instability and flow shears

The radial transport of plasma in the Io torus has been considered to be controlled by interchange instability, whereas the time scale (≈20–80 days) estimated from matching physical chemistry models to spectral observations was much larger than the scale (≤1 day) expected from the process. Previous studies using a magnetospheric convection model suggested that a corotation lag associated with mass ejection from Io can suppress the plasma transport. However, essential processes of fluid dynamics, vortex formation and nonlinear mode interactions were not taken into account but have a critical role in transport and structure development due to plasma instabilities. We performed nonlinear simulations of interchange instability in the Io torus with a reduced magnetohydrodynamic model in two-dimensional dipole magnetic field coordinates. If a single azimuthal perturbation in density is initially given, pure finger-like patterns develop over ≈1 day but are stabilized due to a strong gradient of magnetic fields. If the initial torus density increases, vortex patterns are spontaneously formed through a nonlinear mode coupling, resulting in a collapse of the fingers. In the case of a multiple perturbation, a merging of vortices appears and the torus plasma expands radially to ≈8RJ. The radial transport time scale at the saturation stage of convection energies is estimated to be ≈3 days in this case, while it is ≈72 days in the single perturbation case. By including effects of the corotation lag, a radially striated structure is produced within 5.5−7RJ, but the radial transport is still fast, ≈2 days. We conclude that the radial transport could be controlled by the nonlinear effects of fluids and discuss implications for the ribbon-like structures inside the torus as well as a contribution of the corotation lag.

De lo local a lo regional en el Pacifico Sur Colombiano, 1780 – 1930

El artículo analiza las estrategias, los dispositivos y las instituciones creadas por los colectivos humanos asentados en la región Pacifico Sur Colombiano entre 1780 y 1930. El texto ofrece una explicación sobre el porqué de su adaptación, transformación y flujo de intercambios, y cómo lograron una dinámica propia que en la actualidad ofrece una identidad subregional en el ámbito nacional. El autor toma como núcleo y perspectiva de análisis lo regional, cuya contextualización inicial se da a partir de la dinámica histórico-demográfico-social de sus habitantes, en su mayoría población esclava, seguida de hombres libres y aborígenes. Finalmente, analiza en gruesas líneas procesales y generales la relación región-economía, región-Estado, región-mercado y región-ciudad del objeto de estudio a partir del marco cronológico propuesto. Palabras Clave: Pacifico Sur Colombiano, diáspora africana, región, población.From the regional to the local in the Colombian South Pacific, 1780-1930 AbstractThe article analyzes the strategies, the mechanisms and the institutions created by the human groups settled in the Colombian Pacific South between 1780 and 1930. The text offers an explanation of the why of its adaptation, transformation, and interchange flow, and how they achieved their own dynamic which currently constitutes a sub-regional identity in the national sphere. The author takes regional matters as his nucleus and analytical perspective. The initial contextualization of these matters is given from the historical-demographic-social dynamic of its inhabitants, of which a majority was slaves, followed by free men, and aborigines. Finally, the author analyzes with broad procedural and general strokes, the region-economy, region-state, region-markets, and region-city relationships of the object of the study from the chronological framework proposed. Keywords: Colombian South Pacific, African diaspora, region, settlement.

Oscillatory Mixing for Crystallization of High Crystal Perfection Pharmaceuticals

In-situ Atomic Force Microscopy and Laser Optical Microscopy studies on a fixed single crystal growth, showed that the change of the direction of solution and its relative velocity with respect to the faces of growing crystal, are critical parameters for the minimization of the interfacial instabilities and, in turn, to the structural quality of a crystal. These findings were applied and tested in oscillatory baffled batch crystallizer (OBBC) precipitation experiments, in which, apart from hydrodynamics, all external conditions such as initial supersaturation, crystallization temperature and power density were kept constant. The physical properties (size distribution, surface characteristics, micro-strain content) of the precipitates were characterized by laser light scattering, scanning electron microscopy (SEM), and powder X-ray diffraction, respectively. The analysis of obtained results shows clearly that particles precipitated in OBBC are of significantly higher quality than those produced in conventional mixing using impeller driven batch crystallizer (IDBC). A computational fluid dynamics (CFD) software package, Fluent 5, was used to model dynamical fluid patterns in IDBC and OBBC. The modelling helped to get better appreciation for being able to precipitate particles of considerably higher perfection in OBBC than in IDBC. Also, it accounts for a high degree of equivalency of hydrodynamic conditions that a particle experiences when it grows in OBBC compared to those of a fixed crystal with interchangeable flow direction.

Making interchangeable flow sections for gas-pumping plant

Making interchangeable flow sections for gas-pumping plant

Overall solids movement and solids residence time distribution in a CFB-riser

The residence time distribution (RTD) of solids is essential for the design of CFB reactors where conversion proceeds with time. The residence time distribution for the solids is measured at different working conditions. The resulting average residence times are correlated as function of gas velocity and solids circulation rate and are compared with literature data. In order to predict the RTD of the solids, the solids/gas flow is firstly described by a plug flow with dispersion. A fitting procedure gave experimental Péclet numbers, which were correlated as function of gas velocity and solids circulation rate. A more fundamental approach based on the core/annulus flow structure is thereafter used to predict the residence time. The riser is divided in a dilute core with particles flowing upward and a denser film moving slowly downward along the wall. Particle interchange between the two regions is described by a convective interchange flow. The model is used to predict experimental RTD-curves. The interchange flux between core and annulus corresponds well with radial fluxes reported in literature. Although the RTD is qualitatively well described, experimental curves show a higher dispersion than the calculated ones. To improve the core/annulus approach, further research is necessary.

Panel on transmission impacts related to siting locations of nonutility generation: NUG siting affects the interchange flow exposure to bottlenecks

This discussion addresses the site specific impact that a generator can have upon Florida Power Corporation's (FPC) ability to sustain interchange power transactions. Florida, being a peninsula, has an electrical interface to the north which is both reasonably well defined and predictable. The author discusses the operating criteria of the electrical interface, general siting concepts, NUG siting in FPC's area and its impact on FPC. The author concludes that: generator location can affect the ability to use the transmission system to transfer power; that effect can be measured; incremental transfer improvements in Florida are expensive; all proposed users of these improvements should bear the incremental cost; rate-payers are entitled to the most economical purchases; and utility stockholders should not bear adverse burden of a NUG generator connection. >

High-performance modular spectrophotometric flow cell

A high-performance modular flow cell is described, which can be used in photometric or spectrophotometric detector systems for analytical and preparative scale low-pressure liquid chromatography, flow injection and related techniques. The basic design is that of an inner absorption cell unit sandwiched between two rugged supports. The novel aspects of this sandwiched cell are the wide range of interchangeable flow cell units of different dimensions that can be used, and the way in which the fluid flow occurs, essentially eliminating problems with gas bubbles and giving rapid cell clearance. The cell is compact and its versatility is enhanced by using optical fibre bundles to transmit the light beam to the optical path of the cell and then from there to the detector.

Magnetospheric interchange motions

We describe flux tube interchange motion in a corotating magnetosphere, adopting a Hamiltonian formulation that yields a very general criterion for instability. We derive expressions for field‐aligned currents that reveal the effect of ionospheric conductivity on interchange motion and we calculate instability growth rates. The absence of net current into the ionosphere demonstrates the bipolar nature of interchange flow patterns. We point out that the convection shielding phenomenon in the terrestrial magnetosphere is a direct consequence of the interchange stability of the system. We conclude the paper with an extended analysis of the nature of interchange motion in the Jovian system. We argue that centrifugally driven interchange drives convection and does not give rise to diffusion of Io torus plasma. Neither a large‐scale convection nor other forms of unstable interchange overturning appear adequate to explain the plasma distributions detected at Jupiter.

A keyhole model in penetration welding with a laser

Discusses the interaction of conditions in the liquid metal surrounding the keyhole which is formed when a laser is used as the source of power for welding, with conditions in the vapor itself. The transfer of power and matter across the interface is considered, and a simple model set up for the energy interchange and vapor flow in the keyhole itself. The principal processes are identified. The model is then used to calculate keyhole shapes, and the variation with depth of the related quantities is found.

Shock absorbing wheel hub

Disclosed is a shock absorbing wheel hub for attachment to the axle of a vehicle. The hub has a central flange portion and an annular rim. The rim has a pair of spaced mounting surfaces formed on the periphery thereof for attaching a pair of pneumatic tires with inclined road-engaging treads. A flange is formed on the rim between the mounting surfaces and extends radially outward between the tires. A cylindrical contact surface is formed on the exterior of the flange and carries a tread thereon. The central flange is provided with bores for attachment to the lug bolts of a vehicle axle. Circumferentially spaced resilient spokes extend radially from the central flange and are connected to the hub. A pair of inflation check valves are attached to the rim to communicate respectively with the interior of each pneumatic tire. A flow passage is provided in the rim interconnecting the pneumatic tires for allowing air flow therebetween. An interchangeable flow restricter is mounted in the rim for controlling the flow of air between the two tires. In another embodiment, the spokes have semispherical bearing surfaces formed thereon resiliently held in receptacles formed in the rim. In yet another embodiment, the road-engaging surfaces of the tires are curved from side to side.

Ionosphere‐magnetosphere coupling: 1. Thermal plasma

The past four years have seen a continued increasing interest in the basic processes which connect the thermal plasma population of the ionosphere with that of the outer magnetosphere. Measurement techniques have improved, and we are now able to observe the dynamics of the ionization in these regions as well as their detailed morphology. Although the specific reasons for the formation of the light ion trough and its connection with the plasmapause still elude us, we are beginning to grasp the nature of the many interchange flow processes which seem to play a basic role in the shaping of the well‐known plasmapause and light ion trough features.The thermal plasma population of the magnetosphere has also grown in importance. In addition to attracting the interest of scientists studying the ionosphere and plasmasphere the distribution of thermal plasma has also been found to affect the energetic particle population of the magnetosphere. This interaction between the hot and cold plasma has drawn the attention of workers studying the energetic particles of the radiation belts, the ring current, and the plasma sheet and has further emphasized the tight coupling within the magnetosphere‐ionosphere system.

A lock exchange flow

In this paper the interchange flow between two reservoirs connected by a contraction and containing fluid of different densities is considered. The effect of the boundary layers on the floor and walls of the contraction on the depth of flow in the contraction is discussed for the case of single layer flowing from one reservoir to the other. Next the theory for a denser layer plunging under a stationary layer is developed. In this case there is a discontinuity at the point of intersection of the surfaces of the flowing and the stationary fluids and there are three possible flow régimes depending on whether this discontinuity occurs at, downstream of, or upstream of the contraction.Finally, the case where there is an interchange flow with fluid flowing from each reservoir into the other is introduced. This latter theory parallels that developed by Wood (1968) for the case of two layers flowing from one reservoir through a contraction into another reservoir and as in this case there are two points of control, one at the position of minimum width and one (the virtual point of control) away from this position of minimum width.Experiments are described for a single layer flowing through the contraction and the results of these are used to obtain an indication of the accuracy that could be expected from the experiments with the more complicated exchange flow. The experiments with the exchange flow verified the major elements of the theory.