Existence Of Hysteresis Research Articles

Persistence in Self-Employment Rates before the Great Lockdown: The Case of the UK

A growing body of empirical literature—both on the micro and macro scale—is devoted to exploring the existence of hysteresis—or at least persistence—in self-employment, i.e., whether policy, economic or external shocks have transitory or persistent effects on the probability of survival, and in turn, on the natural rate of self-employment. In aggregate time series studies, the usual method to address this issue has been to look for unit roots by using alternative tests or by using unobservable components models. In this research, we performed a battery of tests and competing approaches to check the robustness of our results with UK self-employment time series. The UK is a suitable case for study because the recent evolution of the UK self-employment rate figures shows a steady growth since the beginning of the millennium. This long-term rise in UK self-employment has attracted the attention of scholars, at least, before the Great Lockdown. We find evidence of hysteresis, while business cycle output variations significantly affect self-employment rates. The article discusses the implications of the findings.

Effect of maturity on the moisture sorption isotherm of chili pepper (Mareko Fana variety)

The moisture sorption isotherm at three maturity levels of the Mareko Fana chili pepper variety (red, brown and green) has been studied in this paper. The sorption isotherm was determined based on the standard static gravimetric method using a glycerol-water mixture in a relative humidity range of 10–92% at three temperature levels and nonlinear regression analysis was used to select suitable sorption models. The Clasius - Clapeyron equation was implemented to determine the isosteric heat of sorption of the chili pepper using the experimental equilibrium moisture content at different sorption temperature levels. The results showed that the GAB model was well fitted for green chili pepper, while the OSWIN model described well the brown and red chili variant. There was a difference in net isosteric heat between the adsorption and desorption isotherm of chili pepper maturity. For green chili, the maximum value of the net isosteric heat was 18 kJ mol−1 and 20 kJ mol−1 for adsorption and desorption isotherms, respectively and it decreased exponentially as moisture content increased. The desorption heat was higher than the adsorption heat for each maturity of chili pepper which indicated the existence of hysteresis in the sorption process. In comparison to literature data reported for different chili varieties, Mareko Fana has a lower heat of sorption and monolayer moisture content.

Application of a Magnetic Resonance Imaging Method for Nondestructive, Three-Dimensional, High-Resolution Measurement of the Water Content of Wet Snow Samples

The infiltration of melted snow water and rainwater into snow can drastically change the form of snow layers. This process is an important factor affecting wet snow avalanches. Accordingly, numerous field surveys and cold room experiments have been conducted to investigate the distribution of water in snow. The common methods of water content measurement (calorimetric and dielectric methods) are implemented by disturbing snow samples to measure them. However, the resolutions obtained are of the order of several centimeters, which hinders the continuous measurement of the water content of a particular sample. Magnetic resonance imaging (MRI), which is typically used in the medical field, can be used to generate a high-resolution three-dimensional (3D) image of the water distribution in samples without destructing them. The luminance of images produced by MRI depends on the volumetric water content of the sample, with luminance increasing with volumetric liquid water content. Therefore, the volumetric liquid water content of the sample can be estimated from its luminance value. Considering this concept, we developed a method to measure the volumetric liquid water content of wet snow samples using MR images. To evaluate the developed method, we prepared several wet snow samples and measured their various volumetric liquid water contents using MRI (θMRI) and the calorimetric method (θcal). θMRI and θcal showed good correlation when compared, with values in the range 0.02–0.46. Therefore, our system can accurately and nondestructively measure water content. The developed method using MRI can measure 3D volumetric liquid water contents with a high resolution (2 mm). Using the developed method, we investigated the hysteresis of the water retention curve of snow based on the measurements of a wetting process (boundary wetting curve) and a drying process (boundary drying curve) of the water retention curve for each sample. Our results indicate the existence of hysteresis in the snow water retention curves and the possibility of modeling it by adopting contexts of soil physics.

Monte Carlo modeling of ferromagnetism of nano-graphene monolayer within Ising model

Abstract Ferromagnetism of nano-graphene layer within Ising model was studied. All results were obtained by using Monte Carlo simulation based on Metropolis algorithm. By applying external magnetic field at room temperature, a gradual transition between ferromagnetic and paramagnetic phases was obtained. This indicates to a potentiality of such a monolayer to be used as a magnetic field sensor. The existence of hysteresis, was established, which strongly depends on the type and magnitude of the interaction strength between the nearest neighbor lattice nodes (spins). Gradual two-step transition between ferromagnetic and paramagnetic phases near absolute zero temperature, was obtained. The results of numerical simulations are in agreement with the available experimental works of other authors.

Structural and magnetic characterization of spin canted mixed ferrite-cobaltites: LnFe0.5Co0.5O3 (Ln = Eu and Dy)

The mixed ferrite-cobaltites LnFe0.5Co0.5O3, with Ln = Eu & Dy have been prepared by a sol-gel method and the samples have been characterized using X-ray diffraction and electron microscopy. The magnetic investigations reveal that both samples ordered in canted antiferromagnetic structures near room temperature. The Dzyaloshinskii-Moriya or antisymmetric exchange interaction induces weak ferromagnetism due to canting of the antiferromagnetically ordered spins. In the case of Ln-Fe-Co orthoferrites, two magnetic sublattices (Ln3+-4f and Fe3+/Co3+-3d) generally align in opposite directions and interesting temperature dependent phenomena: e.g. uncompensated antiferromagnetic sublattices and spin-reorientations, are observed in the system. The existence of hysteresis at low temperature region has been explained in terms of the strength of magnetic interactions between Fe3+ and Co3+ ions with different A-site rare earth cations.

Structural and magnetic properties of frustrated GaxMn(3-x)O4(1.2 ≤ x ≤ 1.6) spinels

We report a systematic study of the structural and magnetic properties of frustrated compounds of GaxMn(3−x)O4 (1.2 ≤ x ≤ 1.6) prepared by solid-state reaction. Using Rietveld refinement of X-ray diffraction patterns and O'Neill-Navrotsky model, we demonstrate that the system GaxMn(3−x)O4 (1.2 ≤ x ≤ 1.6) is an inverse spinel with low inversion parameter, in which Ga3+ replaces Mn3+ cations located in B-sites. The inverse magnetic susceptibility, the shape of ZFC/FC magnetization curves at low temperatures, the existence of hysteresis in all compounds, the frustration parameter and the spontaneous magnetization analysis show that the compounds with x = 1.2–1.4 exhibit a non-collinear ferrimagnetic order and the compounds with x = 1.5–1.6 exhibit a frustrated non-collinear ferrimagnetic order. Spin wave stiffness parameters were determined for each composition using the fitting results of spontaneous magnetization curves. It is demonstrated that for the compounds x = 1.2–1.4 with a non-frustrated ferrimagnetic order, the change of spontaneous magnetization Ms(T) obeys to Bloch's law (T3/2). For x = 1.5–1.6, the compounds exhibit a frustrated ferrimagnetic order, and the Ms(T) shows a deviation from Bloch's law.

Consumption and hysteresis: the new, the old, and the challenge

Consumers are reluctant to change immediately their consumption patterns when confronted with budgetary changes, in spite of fluctuating economic conditions. Their reluctance evokes the notion of hysteresis used by economists to describe the persistent influence of past economic events. The importance of hysteresis in economic research represents a natural consequence of the development of economic sciences and of the pursuit of understanding economic systems’ evolution by taking into account their ‘memory’, their conscience of the past. The present paper represents an attempt to review some of the most relevant approaches to hysteresis in economics and to emphasise the impact of the phenomenon on macroeconomic consumption in Romania. The paper aims at reviewing the application of hysteresis to economic models, and subsequently at constructing a two-phase research on households’ individual final consumption in Romania during 1990 and 2016, employing both the unit root and the so-called ‘true’ approach to hysteresis. The research results indicated the existence of hysteresis at the macroeconomic consumption level, thus revealing several implications for economic policy, inaccessible through the standard economic models.

Hysteresis in the temperature dependence of the intensity of light scattering by boron oxide melt in the 300–450°C temperature range

It has been found that the temperature dependence of the intensity of the polarized V v and depolarized H v components of light scattering by a boron oxide melt in the range of 300–450°C is characterized by the existence of hysteresis: the specific feature of the change in the polarized V v component is the formation of a minimum, while the specific feature in the behavior of the depolarized H v component is associated with the appearance of a maximum in the sample heating mode; the cooling mode is accompanied by a monotonic change in the intensity of the light-scattering components. It has been found also that in the process of a low-temperature stabilization of the melt at 300°C, the polarized V v component after reaching its minimum values increases up to the initial level, while the depolarized H v component after passing its maximum decreases to the values smaller than the initial one. The characteristic time of the change in the intensity of the V v component at 300°C is determined; its value was found to be ~100 min. It has been shown that an insignificant change in the melt synthesis conditions affects the detected features of the intensity change in the range of 300–450°C.

Transition times between the extremum points of the current–voltage characteristic of a resonant tunneling diode with hysteresis

A numerical solution to the problem of transient processes in a resonant tunneling diode featuring a current–voltage characteristic with hysteresis is found for the first time in the context of a coherent model (based on the coupled Schrodinger and Poisson equations) taking into account the Fermi distribution of electrons. The transitions from the high-current to the low-current state and vice versa, which result from the existence of hysteresis and are of great practical importance for ultrafast switches based on resonant tunneling diodes, are studied in detail. It is shown that the transition times for such processes initiated by the application of a small voltage can significantly exceed the characteristic time ℏ/Γ (where G is the width of the resonance level). It is established for the first time that the transition time can be reduced and made as short as the characteristic time ℏ/Γ by applying a sufficiently high voltage. For the parameters of the resonant-tunnelingdiode structure considered in this study, the required voltage is about 0.01 V.

Elimination of the hysteresis effect of PAM actuator: modelling and experimental studies

2), judder-free and resistant to dirt and dust, therefore these actuators are widely used in industrial environment besides electric motors or hydraulic actuators. One of the most mentioned drawbacks of PAMs is the existence of hysteresis. In this paper two experiments related to hysteresis phenomena of PAMs are described. The goal is to present a precise static force model for the hysteresis loop in the force-contraction (force-relative displacement) curve and a LabVIEW based sliding mode controller for hysteresis independent accurate positioning. Using the approximation algorithm for the force produced by the Fluidic Muscle the correlation coefficient R of nearly 1 and 0,01 mm accuracy in positioning is reached.

Static Force Model-Based Stiffness Model for Pneumatic Muscle Actuators

Pneumatic muscle actuators (PMAs) differ from general pneumatic systems as they have no inner moved parts and there is no sliding on the surfaces. During action they reach high velocities, while the power/weight and power/volume rations reach high levels. The main drawbacks of PMAs are limited contraction (relative displacement), nonlinear and time variable behaviour, existence of hysteresis and step-jump pressure (to start radial diaphragm deformation) and also antagonistic connection of PMAs to generate two-direction motion. These make PMAs difficult to modelling and control. In this paper a new stiffness model and the variable-stiffness spring-like characteristics are described and tested using two Fluidic Muscles made by Festo Company. The muscles have the same diameter, but different length.

Investigating empirical implications of hysteresis in day-to-day travel time variability

Day-to-day travel time variability plays a significant role in travel time reliability. Nowadays, travelers not only seek to minimize their travel time on average, but also value its variation. The variation in the mean and the variance of travel time (across days, for the same departure time) has not been thoroughly investigated. A temporary decrease in capacity (e.g. congestion caused by an active bottleneck) leads to a quite significant difference in the variance of travel time for congestion onset and offset periods. This phenomenon results in hysteresis loops where the departure time periods in congestion offset exhibit a higher travel time variance than the ones in congestion onset with the same mean travel time. The aim of this paper is to identify empirical implications that yield to the hysteresis phenomenon in day-to-day travel times. First, empirical hysteresis loop observations are provided from two different freeway sites. Second, we investigate the potential link with the hysteresis observed in traffic networks on macroscopic fundamental diagram (MFD). Third, we build a piecewise linear function that models the evolution of travel time within the day. This allows us to decompose the problem into its components, e.g. start time of congestion, peak travel time, etc. These components, along with their probability distribution functions, are employed in a Monte Carlo simulation model to investigate their partial effects on the existence of hysteresis. Correlation among critical variables is the most influential factor in this phenomenon, which should be further investigated regarding traffic flow and traffic equilibrium principles.

Cooperativity in spin-crossover transition in metalorganic complexes: Interplay of magnetic and elastic interactions

It is of significant technological interest to have an understanding of cooperativity in spin-crossover phenomena observed in metalorganic polymeric complexes. Microscopic origin of this cooperativity has been discussed in literature primarily in terms of elastic interactions. Through Monte Carlo simulation of the model Hamiltonian we show that the superexchange interactions between localized magnetic moments at spin-crossover sites can play a crucial role in cooperativity, depending on the nature of the elastic interactions. While in the case of the effective elastic interaction of ferroelastic nature, inclusion of the above-mentioned exchange interaction produces quantitative changes in the hysteresis loop, for effective elastic interaction of antiferroelastic nature, the existence of hysteresis is found to be dictated entirely by the magnetic exchange interaction. Considering the example of a real material, namely Fe-triazole, employing the material-specific density functional theory calculation, we show the later scenario to be true for these systems. Our study should motivate further investigation on the role of magnetic exchanges in metalorganic polymers.

Analysis of bistability in molecular J aggregates under their resonant optical excitation taking into account multiparticle effects

Using a model of a homogeneous chain of molecules, we have analyzed bistability in resonantly excited J aggregates taking into account three-particle contributions to the exciton-exciton annihilation. These contributions, which have an interference nature, have previously been calculated in a work by B.N. Levinsky, L.A. Nesterov, B.D. Fainberg, and N.N. Rosanov (Opt. Spectrosc. 115 (3), 406 (2013)) in the course of derivation of equations of motion for J aggregates from first principles. Factorization of expectation values that correspond to these contributions leads to a closed system of equations in which not only pair, but also triple, interactions between molecules of the chain are taken into account. Numerical calculations have been performed, and their results have been compared with those obtained in calculations without taking into account three-particle contributions. We have shown that, on the whole, the inclusion of three-particle interference contributions in equations of motion leads to a restriction of the domain of existence of hysteresis. This, in turn, makes it possible to more reliably single out a real range of parameters in which nonlinear optical effects can considerably manifest themselves.

Relationship between mean and day-to-day variation in travel time in urban networks

The day-to-day reliability of transportation facilities significantly affects travel behavior. To better understand how travelers use these facilities, it is critical to understand and characterize this reliability for different facilities. Early work in this area assumed that the variance of day-to-day travel times (a measure of the inverse of reliability) increases proportionally with the mean travel time; i.e., as the mean travel time increases, travel time reliability decreases. However, recent empirical data for a single bottleneck facility and a small urban network suggest a more complex relationship that exhibits hysteresis. When this phenomenon is present, the variance in travel time is larger as the mean travel time decreases (congestion recovery) than as the mean travel time increases (congestion onset). This paper presents an elegant theoretical model to describe the variance of travel times across many days in an urban network. This formulation shows that the hysteresis behavior observed in empirical floating car data on urban networks should not be unexpected, and that it is linked to the hysteresis loops that often exist in the Macroscopic Fundamental Diagram of urban traffic. To verify the validity of this formulation, data from a micro-simulation of the City of Orlando, Florida, are used to derive an observed relationship with which to compare to theory. The simulated data are shown to match the theoretical predictions very well, and confirm the existence of hysteresis in the relationship between the mean and variance of travel times that is suggested by theory. These results can be used as a first step to more accurately represent travel time reliability in future models of traveler decision-making.

Measurement of heat flux in dense air-mist cooling: Part I – A novel steady-state technique

This work presents a technique for characterizing water air-mist cooling of surfaces at temperatures from 200–1200°C while subjected to intense spraying conditions, so that the heat flux could reach values in excess of 10MW/m2. In this new steady-state method, a local region of an air-mist/spray impinges upon the exposed surface of a hot Pt-disk (8mm ∅ by 2.5mm thickness) which is surrounded by an induction coil while both are embedded in a cast ceramic monolith. A digital controller adjusts the output power of a high-frequency generator to balance the induction heating of the Pt-specimen with the heat removed by the boiling of the spray droplets impinging on its active surface, in order to maintain the control temperature of the sample at the predetermined set-point. Measurement of the RMS current flowing through the coil to maintain this temperature, together with the solution of a two-dimensional axi-symmetric computational model of the electromagnetic field and heat conduction equations, enabled estimation of the heat extracted locally by the mist. A rigorous experimental procedure was performed to determine the boiling curves from 200°C to 1200°C and then back to 200°C. The curves for both trajectories revealed that strong boiling hysteresis occurred in the nucleate and transition boiling regimes and that this was almost absent in the stable film boiling regime. On the other hand, hysteresis was not present in thermal loops involving surface temperatures only between 600 and 1200°C. The existence of hysteresis, in a certain temperature interval, points out the importance of considering the thermal history of actual cooling processes when simulating them in the laboratory. The ability of the new technique to maintain the sample temperature for prolonged periods, e.g., hours, enables future studies to improve the understanding of boiling phenomena during intense heat-removal processes. In Part II of this article, the effects that the mist droplet size, droplet velocity and water impact density have on the heat extracted under steady-state conditions from a surface with large superheat are investigated for a wide variety of those characteristics.

Interpreting diel hysteresis between soil respiration and temperature

Increasing use of automated soil respiration chambers in recent years has demonstrated complex diel relationships between soil respiration and temperature that are not apparent from less frequent measurements. Soil surface flux is often lagged from soil temperature by several hours, which results in semielliptical hysteresis loops when surface flux is plotted as a function of soil temperature. Both biological and physical explanations have been suggested for hysteresis patterns, and there is currently no consensus on their causes or how such data should be analyzed to interpret the sensitivity of respiration to temperature. We used a one-dimensional soil CO2 and heat transport model based on physical first principles to demonstrate a theoretical basis for lags between surface flux and soil temperatures. Using numerical simulations, we demonstrated that diel phase lags between surface flux and soil temperature can result from heat and CO2 transport processes alone. While factors other than temperature that vary on a diel basis, such as carbon substrate supply and atmospheric CO2 concentration, can additionally alter lag times and hysteresis patterns to varying degrees, physical transport processes alone are sufficient to create hysteresis. Therefore, the existence of hysteresis does not necessarily indicate soil respiration is influenced by photosynthetic carbon supply. We also demonstrated how lags can cause errors in Q10 values calculated from regressions of surface flux and soil temperature measured at a single depth. Furthermore, synchronizing surface flux and soil temperature to account for transport-related lags generally does not improve Q10 estimation. In order to calculate the sensitivity of soil respiration to temperature, we suggest using approaches that account for the gradients in temperature and production existing within the soil. We conclude that consideration of heat and CO2 transport processes is a requirement to correctly interpret diel soil respiration patterns.

Modeling immune complex-mediated autoimmune inflammation

A number of autoimmune diseases are thought to feature a particular type of self-sustaining inflammation, caused by the deposition of immune complexes (IC) in the inflamed tissue and a consequent activation of local effector cells. The persistence of this inflammation is due to a positive feedback loop, where autoantigen particles released as part of the tissue damage caused by the inflammation stimulate autoreactive B cells, leading to the formation of further immune complexes and their subsequent deposition. We present a mathematical model for the exploration of IC-mediated autoimmune inflammation and its clinical implications. We characterize the possible differences between normal individuals and those susceptible to such inflammation, and show that both random perturbations and bifurcations can lead to disease onset. Our model explains how defects in the mechanisms responsible for cellular debris clearance contribute to the development of disease, in agreement with empirical evidence. Moreover, we show that parameters governing the dynamics of immune complexes, such as their clearance rate, have an even stronger effect in determining the behavior of the system. We demonstrate the existence of hysteresis, implying that once IC-mediated autoimmune inflammation is triggered, its long-term suppression may be difficult to achieve. Our results can serve to guide the development of novel therapies to autoimmune diseases involving this type of inflammation.

Anomalous Hall effect and perpendicular magnetic anisotropy in Sm 28Fe 72 and Sm 32Fe 68 thin films

Sm 28Fe 72 and Sm 32Fe 68 films of 100 nm thickness were grown using DC magnetron sputter deposition and their structure, magnetization, electrical and Hall resistance characteristics were investigated. An increase in electrical resistivity from 4.75×10 −6 to 5.62×10 −6 Ω m and from 2.26×10 −6 to 2.84×10 −6 Ω m for Sm 28Fe 72 and Sm 32Fe 68 films, respectively, with decrease in temperature from 300 to 40 K is attributed to the strain induced anisotropy that dominates at lower temperatures. The positive extraordinary Hall coefficients ( R S ) are observed for both films at 300 and 80 K. The existence of hysteresis indicates that Sm 28Fe 72 and Sm 32Fe 68 films possess perpendicular anisotropy at 300 K. Hysteresis loop becomes narrow at 80 K for both Sm 28Fe 72 and Sm 32Fe 68 films. Magnetization measurements at 300 K exhibiting small coercive field values of 31 and 49 Oe for Sm 28Fe 72 and Sm 32Fe 68 films, respectively, confirm the existence of perpendicular anisotropy at 300 K.

The incongruous observation of magnetic phase separation in La0.85Sr0.15CoO3 spin glass system

Phase separation (PS) in hole-doped cobaltites (La1−xSrxCoxO3) is drawing renewed interest recently. In particular, the magnetic behavior of La0.85Sr0.15CoO3 has been subjected to a controversial debate for the past several years; while some groups show evidence for magnetic PS, others show spin glass (SG) behavior. Here, an attempt is made to resolve the controversy related to “PS versus SG” behavior in this compound. We present the results of a comprehensive investigation of the dc magnetization, ac susceptibility, and the magnetotransport properties of La0.85Sr0.15CoO3 samples. We contemplate that the magnetic PS in La0.85Sr0.15CoO3 is neither intrinsic nor inherent, but it is a consequence of the preparation conditions. It is realized that a low temperature annealed (LTA) sample shows PS whereas the high temperature annealed (HTA) sample shows SG behavior. The Brillouin-like behavior of field cooled dc magnetization and apparently no frequency dependent peak shift in ac susceptibility for the LTA sample characterize it to be of ferromagneticlike whereas a kink in field cooled dc magnetization and a considerable amount (∼3 K) of frequency dependent peak shift in the ac susceptibility for the HTA sample characterize it to be of SG state. The magnetotransport properties show that the HTA sample is more semiconducting as compared to the LTA sample. This is interpreted in terms of the presence of isolated as well as coalescing metallic ferromagnetic clusters in the case of LTA sample. The magnetoresistance (MR) at 10 K for the HTA sample exhibits a huge value (∼65%) as compared to the LTA sample, and it monotonically decreases with the rise in temperature. Such a high value of MR in the case of HTA sample is strongly believed to be due to the spin dependent part of random potential distribution. Further, the slow decay of remnant magnetization with progress of time and the existence of hysteresis at higher temperatures (up to 200 K) in the case of LTA sample as compared to the HTA sample clearly unveil different magnetic states associated with them.