Processes In Loops Research Articles

A study of pump-driven heat pipe loop and heat pump loop under the same heat transfer environment based on entransy theory

Both pump-driven heat pipe loops and heat pump loops can operate in heat transfer environments where the temperature of the heat source is higher than that of the heat sink. To investigate the fundamental utilization of input work during heat transfer processes in two distinct loops, this study employed the theory of entransy to conduct an in-depth analysis of the heat transfer processes in pump-driven heat pipe loops and heat pump loops. The research initially explored these loops’ limiting conditions for cyclic heat transfer. Subsequently, the concept of antransy was introduced to elucidate the substantial role of input work in the heat transfer processes. By the antransy, this paper further analyzed the practical utilization degree of input work, providing theoretical insights for optimizing heat transfer systems. The results indicate that the form of loops and the heat transfer conditions influence the magnitude of input work. Precisely, the input work in the loops compensates for the entransy loss that occurs when the working fluid exchanges heat with the environment. More input work does not necessarily translate into more substantial heat transfer. Furthermore, the utilization degree of input work in different loops depends on factors such as the heat transfer environment, the amount of heat transferred, and the heat capacity of the working fluid. The concept of antransy effectively assesses the efficient utilization of input work in these loops. By analyzing the antransy generated in the system, we can better understand how efficiently the input work is utilized in the heat transfer process. The research findings have enriched the field of entransy theory, providing new insights and perspectives into this area of study. Moreover, the results can promote and offer fresh ideas for optimizing cyclic heat transfer systems.

Fine Structures of Type-IV Solar Radio Bursts Associated with Stationary and Moving Sources

Various types of fine structure in the continuum emission of type-IV radio bursts are considered asapplied to different types of radiation sources, both stationary and moving. In the case of stationary sources,the origin of the fine structure is associated both with processes in individual magnetic loops (quasi-periodicacceleration and magnetohydrodynamic waves), and with large-scale processes associated with the propagationof magnetohydrodynamic disturbances, the formation of loop arcades, and processes of discrete accelerationof particles synchronous with them, causing the pulsating nature of radio emissions. For the case of amoving source, the generation mechanism largely depends on the magnetic structure of the source (anexpanding magnetic arc or an isolated plasma cloud). In this case, the connection with coronal mass ejectionsand shock waves is also important. Secondary pulsations are explained by a magnetohydrodynamic fluctuationsource in the form of a magnetic loop or cloud. The absence of other fine structures in the continuum ofmoving type-IV bursts may be due to the critical angle of the loss cone for the excitation of whistlers

Parkinsonism Is Associated with Altered SMA-Basal Ganglia Structural and Functional Connectivity in Frontotemporal Degeneration.

Patients with frontotemporal degeneration (FTD) often manifest parkinsonism, which likely results from cortical and subcortical degeneration of brain structures involved in motor control. We used a multimodal magnetic resonance imaging (MRI) approach to investigate possible structural and/or functional alterations in FTD patients with and without parkinsonism (Park+ and Park-). Thirty FTD patients (12 Park+, 18 Park-) and 30 healthy controls were enrolled and underwent 3T MRI scanning. MRI analyses included: (1) surface-based morphometry; (2) basal ganglia and thalamic volumetry; (3) diffusion-based probabilistic tractography of fiber tracts connecting the supplementary motor area (SMA) and primary motor cortex (M1) to the putamen, globus pallidus, and thalamus; and (4) resting-state functional connectivity (RSFC) between the aforementioned regions. Patients in Park+ and Park- groups showed comparable patterns of cortical thinning in frontotemporal regions and reduced thalamic volume with respect to controls. Only Park+ patients showed reduced putaminal volume and reduced fractional anisotropy of the fibers connecting the SMA to the globus pallidus, putamen, and thalamus, with respect to controls. Park+ patients also showed decreased RSFC between the SMA and putamen with respect to both Park- patients and controls. The present findings support the hypothesis that FTD patients with parkinsonism are characterized by neurodegenerative processes in specific corticobasal ganglia-thalamocortical motor loops.

MATHEMATICAL AND COMPUTER MODELLING REGULATORIKA OF HIERARCHICAL MOLECULAR-GENETIC SYSTEMS

The progress achieved in biology during the last century has led to development of mathematical and computer modelling of functioning regulatory mechanisms (regulatorika) in molecular-genetic processes in living systems. In this work we consider one of the possible methods for mathematical and computer mod- elling of molecular-genetic systems regulatorika. The corresponding equations (in the class of delay functional-differential equations) are developed, using the approaches by B.Goodwin, Bl. Sendov, M. Eigen, B.A. Ratner, and taking into account of tempo- rary relations, presence of multifunctional feedback and cooperative nature of processes in cell's regulatory loops. Results on the regulatorika for uniform molecular-genetic systems, as well as the problem of the origin and development of hierarchical molecular- genetic systems are considered. Results of using the considered method for analyzing cell's molecular-genetic systems in the presence of the alien genes (on the example of hepatic cell infections by hepatitis B virus) are given. 1 Introduction The analysis of main protein-ferments participating in the specific func- tioning of cells in a multicellular organism shows, that each cell contains different complex of protein molecules, though all cells have the same set of chromosomes and, consequently, identical genetic information (1, 2, 3). It happens because in eukaryotic cells there is mech- anism of hierarchical organizations of molecular-genetic system, regulating genes activity: which groups of genes at the moment must be active and which genes should be in the inactive condition. Existence of biochemical properties and processes, inherent all cells of the organism (syntheses of energy proteins, amino acid, to maintain and build membrane, etc) shows that there are universal groups of genes functioning in all cells regardless of specialization. Remaining part of genes consists of groups of general genes (its operation depends on activity conditions in universal groups of genes), containing information on general functions characteristic for many, but not all cells and groups of specific genes (its functioning depends on activity conditions of universal and general genes groups), keeping information on strictly specific functions of concrete cells (4). Under such approach, the whole cell genome of multicellular organism works as evolutionary established hierarchical system of universal, general and specific genes groups (Figure 1). Hierarchical organization of molecular-genetic systems is of the utmost importance in regulatorika of intracellular processes and cellular functions. Their account makes it possible to carry out studying mechanisms of origin, existence and development of living systems when quantitatively analyzing activity patterns of molecular-genetic systems. In this work we develop the mathematical modelling of genes activity (section 2), possible equations of molecular-genetic systems regulatorika (sections 3,4) and certain problems concerning the mathematical and computer modelling of hierarchical molecular-genetic systems (sections

High-density Off-limb Flare Loops Observed by SDO

Abstract The density distribution of flare loops and the mechanisms of their emission in the continuum are still open questions. On 2017 September 10, a prominent loop system appeared during the gradual phase of an X8.2 flare (SOL2017-09-10), visible in all passbands of SDO/AIA and in the white-light continuum of SDO/HMI. We investigate its electron density by taking into account all radiation processes in the flare loops, i.e., the Thomson continuum, hydrogen Paschen and Brackett recombination continua, as well as free–free continuum emission. We derive a quadratic function of the electron density for a given temperature and effective loop thickness. By absolutely calibrating SDO/HMI intensities, we convert the measured intensities into electron density at each pixel in the loops. For a grid of plausible temperatures between cool (6000 K) and hot (106 K) structures, the electron density is computed for representative effective thicknesses between 200 and 20,000 km. We obtain a relatively high maximum electron density, about 1013 cm−3. At such high electron densities, the Thomson continuum is negligible and therefore one would not expect a significant polarization degree in dense loops. We conclude that the Paschen and Brackett recombination continua are dominant in cool flare loops, while the free–free continuum emission is dominant for warmer and hot loops.

Determination of the Heat-Exchange Characteristics of Low-Pressure Heat-Exchangers for Lead and Lead-Bismuth Cooled Loops

Heat removal during transient processes in nuclear power installations and bench loops cooled by lead and lead-bismuth coolant is studied. It is shown that low-pressure heat-exchange equipment is effective. The studies were conducted in a non-isothermal loop with circulating of lead coolant at 450–500°C, average speed in the narrow section of the gap in longitudinal flow over the heat-exchange surface 0.1–1.05 m/sec, Peclet number 300–3300, and the oxygen thermodynamic activity in lead 1–10–3. The processes occurring in a non-isothermal liquid-metal loop with an experimental heat-exchange section model the dependence of the heat-exchange characteristics on impurity mass transfer in the loop.

Control loops of a supply servo drive

The electric motor in a supply drive is analyzed. The model employed takes account of the motor’s electrical and mechanical parameters and permits reproduction of the processes in the control loops of supply drives.

THEn-DISTRIBUTION OF ELECTRONS AND DOUBLE LAYERS IN THE ELECTRON-BEAM-RETURN-CURRENT SYSTEM OF SOLAR FLARES

We investigate processes in the electron-beam-return-current system in the impulsive phase of solar flares to answer a question about the formation of the n-electron distribution detected in this phase of solar flares. An evolution of the electron-beam-return-current system with an initial local density depression is studied using a three-dimensional electromagnetic particle-in-cell model. In the system the strong double layer is formed. Its electric field potential increases with the electron beam flux. In this electric field potential, the electrons of background plasma are strongly accelerated and propagate in the return-current direction. The high-energy part of their distribution at the high-potential side of the strong double layer resembles that of the n-distribution. Thus, the detection of the n-distributions, where a form of the high-energy part of the distribution is the most important, can indicate the presence of strong double layers in solar flares. The similarity between processes in solar flare loops and those in the downward current region of the terrestrial aurora, where the double layers were observed by FAST satellite, supports this idea.

Interplay between the antiferromagnetic spin configuration and the exchange bias effect in [Pt/Co]8/CoO/Co3Pt trilayers

The exchange bias effect in [Pt/Co]${}_{8}/$CoO/Co${}_{3}$Pt trilayers was studied. The individual reversal of the ferromagnetic layers was analyzed for two cooling configurations in which the magnetic moments were aligned parallel or antiparallel to each other. The exchange bias fields of the ferromagnetic films can be set independently for each configuration, depending on their respective initial magnetization orientations. Still, magnetic coupling between both the [Pt/Co]${}_{8}$ and the Co${}_{3}$Pt layers is unambiguously observed below the blocking temperature of the antiferromagnetic CoO. This phenomenon is studied by looking at isolated magnetic reversal processes in minor loops and is explained by temporary modifications of the CoO bulk spin structure. Specifically, we suggest that the frozen part of the antiferromagnetic grains is responsible for the coupling.

HCLL and HCPB Coolant Purification System: Preliminary Measurement and Instrumentation Plan

The Coolant Purification System (CPS) together with the Tritium Extraction System (TES) and Helium Cooling System (HCS) are the principal auxiliary circuits of HCLL and HCPB TBMs to be tested in ITER. Among them, CPS is used to extract tritium from the cooling primary circuit as well as to guarantee the removal of gas impurities which could interact with structural material. Based on considerations in terms of safety, tritium accountancy and process control, instrumentation philosophy requires real-time tritium monitoring (which might be not very accurate) to control the processes in both TBM helium loops and special tritium accountancy procedure with regard to the interface with other sub-systems of the Tritium Plant. Furthermore, in addition to chemical speciation of the flow, the control of the process requires the measurement of other parameters such as flow rates, pressures and temperatures. For each monitored parameter, this paper describes the most suitable technologies, including a review of advantages, drawbacks and possible ways of improvement.

The activity of late-type stars: the Sun among stars with cyclic activity

The coronal and chromospheric emission of several hundred late-type stars whose activity was recently detected are analyzed. This confirms the previous conclusion for stars of HK project that there exist three groups of objects: active red M dwarfs, G-K stars with cyclic activity, and stars exhibiting high but irregular activity. The X-ray fluxes, EUV-spectra, and X-ray cycles can be used to study the main property of stellar coronas—the gradual increase in the number of high-temperature (T ≥ 10 MK) regions in the transition from the Sun to cyclically active K dwarfs and more rapidly rotating F and G stars with irregular activity. The level of X-ray emission is closely related to the spottedness of the stellar surface. The correlation between the chromospheric and coronal emission is weak when the cycles are well-defined, but becomes strong when the activity is less regular. Unexpectedly, stars whose chromospheric activity is even lower than that of the Sun are fairly numerous. Common and particular features of solar activity among the activity of other cyclically active stars are discussed. Our analysis suggests a new view of the problem of heating stellar coronas: the coronas of stars with pronounced cycles are probably heated by quasistationary processes in loops, while prolonged nonstationary coronal events are responsible for heating the coronas of F and G stars with high but irregular activity.

Collisional transport in axisymmetric plasma columns with strong longitudinal flows: application to solar loops

In this work we analyze the transport processes in solar loops considering a collisional plasma and high longitudinal plasma flow. The general theory of the neoclassical transport in toroidal configurations with a noncircular cross-section is applied to explain the transport processes in some kinds of solar loops, modeling the solar loop as a toroidal plasma column. The plasma is assumed to be in the collisional regime and to have particle longitudinal flow along the solar loop axis. The poloidal velocity and the radial fluxes of the particles and the ion heat flux are derived in this article. It is shown that the particle poloidal velocity can be measured giving rise to the possibility of having additional connections between the plasma macroscopic parameters, which are very important for the solar loops diagnostic. It is also shown that the particle and heat fluxes are on the ''classical'' level, within the factor of an order of magnitude. We hope that such an approach (together with other theories) can help to explain the transport processes in solar loops, whose shapes are similar to toroidal configurations.

A system model for ISO 9000 standards

A system model for ISO 9000 series of standards is proposed. It is based on the principles of system thinking. The author points out in the paper two system cycles that should be practised to make the system model visible: a system cycle on structure consisting of three tiers; and a system cycle on processes in links and loops spanning the structure. The system cycle on structure represents a long‐term performance management system, whereas the system cycle on processes in links and loops represents a short‐term performance management system. What keeps the quality management system going is the perennial and collective commitment.

Fault Detection in a Multivariable Chemical Process by Monitoring Process Dynamics

A fault detection method is described which is based on monitoring quantities that describe the dynamic characteristics of processes in individual control loops. These quantities are derived from discrete-time, input-output process models estimated from sampled process data. The models are widely applicable and do not require modelling from first principles. The approach is investigated applied to detecting faults in a simulated continuous stirred tank reactor under digital computer control. Results illustrate the potential of the method for fault detection in the presence of unmodelled dynamics and random disturbances, and for enhancing the data available to improve fault diagnosis.

Solar flares: The gradual phase

One has to distinguish between two kinds of the gradual phase of flares: (1) a gradual phase during which no energy is released so that we see only cooling after the impulsive phase (a confined flare), and (2) a gradual phase during which energy release continues (a dynamic flare). The simplest case of (1) is a single-loop flare which might provide an excellent opportunity for the study of cooling processes in coronal loops. But most confined flares are far more complicated: they may consist of sets of unresolved elementary loops, of conglomerates of loops, or they form arcades the components of which may be excited sequentially. Accelerated particles as well as hot and cold plasma can be ejected from the flare site (coronal ‘tongues’, flaring arches, sprays, bright and dark surges) and these ejecta may cool more slowly than the source flare itself. However, the most important flares on the Sun are flares of type (2) in which a magnetic field opening is followed by subsequent reconnection of fieldlines that may continue for many hours after the impulsive phase. Therefore, the main attention in this review is paid to the gradual phase of this category of long-decay flares. The following items are discussed in particular: The wide energy range of dynamic flares: from eruptions of quiescent filaments to most powerful cosmic-ray flares. Energy release at the reconnection site and modelling of the reconnection process. The ‘post-flare’ loops: evidence for reconnection; observations at different wavelengths; energy deposit in the chromosphere, chromospheric ablation, and velocity fields; loops in emission; shrinking loops; magnetic modelling. The gradual phase in X-rays and on radio waves. Post-flare X-ray arches: observations, interpretation, and modelling; relation to metric radio events and mass ejections, multiple-ribbon flares and anomalous events, hybrid events, possible relations between confined and dynamic flares.

Solar Flares: The Gradual Phase

AbstractOne has to distinguish between two kinds of the gradual phase of flares: (1) a gradual phase during which no energy is released so that we see only cooling after the impulsive phase (a confined flare), and (2) a gradual phase during which energy release continues (a dynamic flare).The simplest case of (1) is a single-loop flare which might provide an excellent opportunity for the study of cooling processes in coronal loops. But most confined flares are far more complicated: they may consist of sets of unresolved elementary loops, of conglomerates of loops, or they form arcades the components of which may be excited sequentially. Accelerated particles as well as hot and cold plasma can be ejected from the flare site (coronal ‘tongues', flaring arches, sprays, bright and dark surges) and these éjecta may cool more slowly than the source flare itself.However, the most important flares on the Sun are flares of type (2) in which a magnetic field opening is followed by subsequent reconnection of fieldlines that may continue for many hours after the impulsive phase. Therefore, the main attention in this review is paid to the gradual phase of this category oflong-decay flares. The following items are discussed in particular: The wide energy range of dynamic flares: from eruptions of quiescent filaments to most powerful cosmic-ray flares. Energy release at the reconnection site and modelling of the reconnection process. The ‘post-flare’ loops: evidence for reconnection; observations at different wavelengths; energy deposit in the chromosphere, chromospheric ablation, and velocity fields; loops in emission; shrinking loops; magnetic modelling. The gradual phase in X-rays and on radio waves. Post-flare X-ray arches: observations, interpretation, and modelling; relation to metric radio events and mass ejections, multiple-ribbon flares and anomalous events, hybrid events, possible relations between confined and dynamic flares.

Analysis of transient processes in nuclear-reactor loops

An algorithm is presented which may play a significant role for real nuclear-reactor loops in multivariant calculations by its economy. The TRANS7 algorithm has been developed for the solution of this problem; the TRANS7 algorithm performs the numerical integration of the thermohydraulic equations of one- and two-phase flows and the heattransfer equations in the fuel elements. A mathematical model is presented which is closed by empirical relations for slipping and friction in the two-phase flow and for heating of the water in the nonequilibrium-boiling zone. The thermophysical properties of water and steam are calculated using a bundle of programs and introlduced in the computer memory in tabular form, which is suitable for interpolation with respect to the pressure and heat ontent. When considering a group of experiments, the TRANS7 algorithm gives completely satisfactory agreement of the theoretical and experimental data.

Transient heat transfer and fluid mechanics of a recirculating pressurized water loop during blowdown and cold water injection

AbstractMathematical models, in the form of computer codes, are used to evaluate the performance of process and safety systems of CANDU nuclear reactors during normal operation and postulated accident conditions. To validate the models, predictions are made of the transient heat transfer and fluid mechanics processes in pressurized water loops following simulated pipe ruptures. These loops have the essential geometric and physical characteristics of a CANDU reactor primary heat transport system. Comparisons with data from loops of different scales over the conditions of interest (blowdown and cold water injection) are used to illustrate that the models predict the trends in the experiments adequately when the assumptions inherent in the model (e. g. equal steam and water velocities) are valid. To improve accuracy in cases where these assumptions do not apply, a more sophisticated representation of two‐phase flow is required.

Computer-aided design of closed-loop control systems

A method is described whereby linear, single-input, single-output control systems can be designed by a computer-aided design process in which the Nyquist diagram of the system is displayed automatically on a cathode ray oscilloscope coupled to the computer. The designer communicates with the computer using his intuitive understanding of the design process coupled with the rapid computation and display offered by the computer. The method allows the rapid design of the compensating devices required to control high order processes in feedback loops. The article includes a numerical example in which the parameters of a typical pneumatic three-term controllers are computed to match a process plant having five simple lags.