Hysteretic Effects Research Articles

The current hysteresis effect of tower-like MoS2 nanocrystalline film for field emission and memristor applications

In this work, we investigate the hysteresis effect of the current-voltage characteristic for the magnetron sputtered molybdenum disulfide (MoS2) nanocrystalline films. The field emission hysteresis of MoS2 cold cathode is studied by sweeping mode with voltage upward/downward, the vacuum pressure has a remarkable effect on the hysteresis of the emission current and overall the hysteresis becomes more prominent as pressure rises. Besides, we also demonstrate the current-voltage behaviors of MoS2 film using thermal evaporated Al dot as top electrode and copper foil substrate as bottom electrode. The Al/MoS2/Cu configuration device presents an obvious current hysteretic effect and the current increases with the increase of the voltage sweeping times. The possible mechanism of the hysteresis has been proposed herein and also investigations provide a great promise for the development of magnetron sputtered MoS2 nanocrystalline films in applications such as field emitters and memristor devices.

Application of analytical model in the prediction of dynamic responses and fatigue damage of flexible risers: Part II – Dynamic analysis of flexible risers in large-scale domain using a direct moment correction method

In recent years, the dynamic responses of flexible risers have been the focus of many researchers. Most flexible risers undergo a substantial level of irregular motion from environmental loadings, which involves a continuous slip of helical wires. The slip of helical wires especially leads to a hysteretic effect by reducing the bending stiffness, making it hard to predict the dynamic responses of flexible risers. The current study, as an extension to Part I, presents a new large-scale dynamic analysis method for flexible risers. The suggested method creates a large-scale model for the dynamic analysis that considers a geometric and bending nonlinearity of flexible risers. The kinematics of each beam element is formulated based on a Green-Lagrangian strain and the interaction with the seabed, providing a realistic analysis of flexible risers. In particular, the current study introduces a direct moment correction method that modifies the internal force vector using an improved analytical model. The improved analytical model is assigned at each node of the large-scale model and estimates an accurate bending hysteresis curve considering the effect of shear deformation and varying tension. The suggested method corrects the bending moment and shear force of all beam elements based on the bending hysteresis curves obtained from the improved analytical model, by which a complex bending behavior of flexible risers is reflected in a large-scale domain. As a result, this study achieves a more accurate prediction of the dynamic responses and fatigue damage of flexible risers. A new dynamic analysis program, called OPFLEX, is developed herein based on the suggested analysis method. Using the developed program, the current study conducts several numerical investigations to identify the effect of the shear deformation and varying tension. Consequently, it is confirmed that the shear deformation of internal layers reduces the fatigue damage of helical wires by delaying the increase of internal stress. It is also identified that the effect of varying tension deteriorates the fatigue life of flexible risers through a continuous change of contact pressure during bending.

Regulation of the order–disorder phase transition in a Cs2NaFeCl6 double perovskite towards reversible thermochromic application

Multifunctional lead-free double perovskites demonstrate remarkable potential towards applications in various fields. Herein, an environmentally-friendly, low-cost, high-throughput Cs2NaFeCl6 single crystal with exceedingly high thermal stability is designed and grown. It obtains a cubic lattice system in the temperature range of 80–500 K, accompanied by a completely reversible chromatic variation ranging from yellow to black. Importantly, the intriguing thermochromism is proved to own extremely high reproducibility (over 1000 cycles) without a hysteretic effect, originating from its structural flexibility that including (i) the noteworthy distortion/deformation of [NaCl6]5− and [FeCl6]3− octahedra; (ii) order–disorder arrangement transition of [NaCl6]5− and [FeCl6]3− octahedra as the function of temperature. This study paves the way towards a new class of smart windows and camouflage coatings with an unprecedented colour range based on a Cs2NaFeCl6 perovskite.

An evolutionary analysis of new energy and industry policy tools in China based on large-scale policy topic modeling.

This study investigates the evolution of provincial new energy policies and industries of China using a topic modeling approach. To this end, six out of 31 provinces in China are first selected as research samples, central and provincial new energy policies in the period of 2010 to 2019 are collected to establish a text corpus with 23, 674 documents. Then, the policy corpus is fed to two different topic models, one is the Latent Dirichlet Allocation for modeling static policy topics, another is the Dynamic Topic Model for extracting topics over time. Finally, the obtained topics are mapped into policy tools for comparisons. The dynamic policy topics are further analyzed with the panel data from provincial new energy industries. The results show that the provincial new energy policies moved to different tracks after about 2014 due to the regional conditions such as the economy and CO2 emission intensity. Underdeveloped provinces tend to use environment-oriented tools to regulate and control CO2 emissions, while developed regions employ the more balanced policy mix for improving new energy vehicles and other industries. Widespread hysteretic effects are revealed during the correlation analysis of the policy topics and new energy capacity.

Evidence of Orbital Ferromagnetism in Twisted Bilayer Graphene Aligned to Hexagonal Boron Nitride.

We have previously reported ferromagnetism evinced by a large hysteretic anomalous Hall effect in twisted bilayer graphene (tBLG). Subsequent measurements of a quantized Hall resistance and small longitudinal resistance confirmed that this magnetic state is a Chern insulator. Here, we report that when tilting the sample in an external magnetic field, the ferromagnetism is highly anisotropic. Because spin-orbit coupling is weak in graphene, such anisotropy is unlikely to come from spin but rather favors theories in which the ferromagnetism is orbital. We know of no other case in which ferromagnetism has a purely orbital origin. For an applied in-plane field larger than 5 T, the out-of-plane magnetization is destroyed, suggesting a transition to a new phase.

Negative capacitance effects in ferroelectric heterostructures: A theoretical perspective

In a heterogeneous system, ferroelectric materials can exhibit negative capacitance (NC) behavior given that the overall capacitance of the system remains positive. Such NC effects may lead to differential amplification in local potential and can provide an enhanced charge and capacitance response for the whole system compared to their constituents. Such intriguing implications of NC phenomena have prompted the design and exploration of many ferroelectric-based electronic devices to not only achieve an improved performance but potentially also overcome some fundamental limits of standard transistors. However, the microscopic physical origin as well as the true nature of the NC effect, and direct experimental evidence remain elusive and debatable. To that end, in this article, we provide a comprehensive theoretical perspective on the current understanding of the underlying physical mechanism of the NC effect in the ferroelectric material. Based upon the fundamental physics of ferroelectric material, we discuss different assumptions, conditions, and distinct features of the quasi-static NC effect in the single-domain and multi-domain scenarios. While the quasi-static and hysteresis-free NC effect was initially propounded in the context of a single-domain scenario, we highlight that similar effects can be observed in multi-domain FEs with soft domain-wall (DW) displacement. Furthermore, to obtain the soft-DW, the gradient energy coefficient of the FE material is required to be higher as well as the ferroelectric thickness is required to be lower than some critical values. If those requirements are not met, then the DW becomes hard and their displacement would lead to hysteretic NC effects, which are adiabatically irreversible. In addition to the quasi-static NC, we discuss different mechanisms that can potentially lead to the transient NC effects. Furthermore, we discuss different existing experimental results by correlating their distinct features with different types of NC attributes and provide guidelines for new experiments that can potentially provide new insights on unveiling the real origin of NC phenomena.

Estimating the Daily NO2 Concentration with High Spatial Resolution in the Beijing–Tianjin–Hebei Region Using an Ensemble Learning Model

Nitrogen dioxide (NO2) is an important pollutant related to human activities, which has short-term and long-term effects on human health. An ensemble learning model was constructed and applied to estimate daily NO2 concentrations in the Beijing–Tianjin–Hebei region between 2010 and 2016. A variety of predictive variables included satellite-based troposphere NO2 vertical column concentration, meteorology, elevation, gross domestic product (GDP), population, land-use variables, and road network. The ensemble learning model achieved two things: a 0.01° × 0.01° grid resolution and the estimation of historical data for the years 2010–2013. The ensemble model showed good performance, whereby the R2 of tenfold cross-validation was 0.72 and the R2 of test validation was 0.71. Meteorological hysteretic effects were incorporated into the model, where the one-day lagged boundary layer height contributed the most. The annual NO2 estimation showed little change from 2010 to 2016. The seasonal NO2 estimation from highest to lowest occurred in winter, autumn, spring, and summer. In the annual maps and seasonal maps, the NO2 estimations in the northwest region were lower than those in the southeast region, and there was a heavily polluted band in the south of the Taihang Mountains. In coastal areas, the annual NO2 estimations were higher than the NO2 monitored values. The drawback of the model is underestimation at high values and overestimation at low values. This study indicates that the ensemble learning model has excellent performance in the simulation of NO2 with high spatial and temporal resolution. Furthermore, the research framework in this study can be a generally applied for drawing implications for other regions, especially for other cities in China.

Role of cation-mediated recombination in perovskite solar cells

The origin of the hysteresis in the current–voltage (J–V) characteristics in perovskite solar cells (PSCs) is one of the most debated topics of recent years. Hysteretic effects are connected with the slow redistribution of ionic defects during the voltage sweep. Existing literature focuses on the potential screening due to accumulated ions, solely, while neglecting the possibility of charge trapping and subsequent recombination via ions. We investigate the role of cation-mediated recombination of ions using time-dependent drift–diffusion simulations in MAPbI3 PSCs. Slow-moving cations are considered as traps for the electrons. Trapped electrons can subsequently recombine non-radiatively with holes. We analyze the role of the cation-mediated trapping and its parameters (capture coefficient, cation energy, ion mobility) as well as the scan rate on the device performance. For shallow cation energies, a decrease in open-circuit voltage and slight enhancement in hysteresis is observed. Deep cation energies lead to a substantial deterioration of device performance and large hysteresis enhancement. The presented study emphasizes the importance of considering the interaction of ions with charge carriers beyond the simple electrostatic models to improve our understanding of PSCs.

Numerical study on the oxidation reaction characteristics of coal under temperature-programmed conditions

To understand the oxidation reaction of coal and predict and control generation and development of coal fires, a one-step global dynamic model of the chemical reaction between coal and oxygen considering multi-material actions was established. A volume-averaged oxygen consumption rate (OCR) to evaluate the characteristics of the oxidation reaction of coal was proposed. The results demonstrate that, in the reaction between coal and oxygen, the dominant effects of temperature and oxygen concentration on the reaction rate of coal oxidation also change. There is a certain time-lag between changes of the temperature during coal oxidation and combustion and the reaction rate: the changes of temperature parameters fail to reflect the instantaneous reaction rate in real time. By changing the volume fraction of oxygen and the programmed heating rate, it is found that increasing the volume fraction of oxygen and the heating rate both can promote the reaction between coal and oxygen and reduce the hysteretic effects of heating in the reaction under external heating. Therefore, controlling the temperature storage conditions is beneficial to preventing the oxidation reaction of coal in its early stage, while changing the oxygen supply conditions can control the development of coal spontaneous combustion in its later stage.

Modeling of wedge-pin joint for the dynamic analysis of a planar temporary demountable structure

In order to understand deeply the dynamic behavior of a Temporary Demountable Structure (TDS), a 2-D analytical model of the Wedge-Pin Joint (WPJ) is established. This model takes into account of the semi-rigidness of the vertical contact and the sliding between beam and column based on the frictional shear-slip mechanism. The analytical WPJ model is validated by comparing with the dynamic responses of the TDS modeled with that obtained from the finite element model under harmonic load. Furthermore, a thorough dynamic analysis of the TDS subjected to a bipedal walking force is conducted. Results show that the hysteretic effect of the WPJs can be induced in the system. It is strongly affected by the amplitude of excitation, and a larger excitation does not mean a stronger hysteresis. This can be interpreted by that large horizontal contact force for joints resulted from strong excitation in horizontal direction yields high friction, which enhances the clamping effects in vertical and then weakens the hysteretic effect of WPJs. In addition, the vertical slip for joint is limited to a small value due to a relative small acceleration, this small vertical slip leads to a small of hysteretic loop. Finally, it is also found that the semi-rigidness of WPJs can apparently increase the deformation and acceleration of the system in both horizontal and vertical directions. This research provides for the first time an analytical model of WPJs of TDS, which will be beneficial to the future research of human-TDS interaction.

Bayesian model identification of higher-order frequency response functions for structures assembled by bolted joints

This paper proposes a procedure to identify a stochastic Bouc-Wen model for describing the dynamics of a structure assembled by bolted joints considering vibration data. The proposed identification approach is expressed into a Bayesian framework to take into account the data fluctuations related to uncertainties in the measurement process. The calibration of the model parameters uses the analytical expressions of the higher-order frequency response functions (FRFs) for approximating experimental measurements. The Metropolis-Hastings algorithm is employed for approximating posterior distributions. Once calibrated, the applicability of the probabilistic Bouc-Wen model is evaluated, and its dynamical behavior is compared with experimental measurements from the bolted structure. The results show that the stochastic version of the Bouc-Wen model can predict with adequate agreement, including hysteretic effects, the output of the jointed structure considering several excitation amplitudes.

Employment hysteresis: an argument for avoiding front-loaded fiscal consolidations in the eurozone

The austerity policies applied by the eurozone peripheral governments under the Troika financial assistance programmes have contributed to a sharp reduction in aggregate demand, regardless of the unconventional measures undertaken by the European Central Bank (ECB). The ECB decreased the interest rate on the main refinancing operations to zero and has been buying assets from banks on a massive scale under the Expanded Asset Purchase Programme. The fact that these extraordinary measures have not been enough to promote a strong recovery shifts the focus back onto fiscal policy. The value of impact fiscal multipliers and the size of hysteretic effects are key factors for assessing the effects of fiscal policy. There is widespread evidence that public expenditure multipliers are greater than one, especially when the economy is depressed. However, less is known about the importance of hysteresis effects. Using the linear play hysteresis operator, we find that hysteresis effects are important in the eurozone peripheral countries. Large fiscal impact multipliers combined with the presence of hysteresis implies that front-loaded austerity depresses the economy in the short run, and these effects may persist in the long run.

Permeability Alteration of Carbonate Reservoir Rock Under Cyclic Geomechanical Treatment

The paper presents integral analysis of data obtained on carbonate reservoir rocks of Bashkir and Tournai formations (Republic of Tatarstan, Russia) under specially designed experimental studies for measuring rock permeability alteration under changes of pore pressure with constant triaxial outer (geostatic) stresses. Characteristic hysteretic effects of permeability alteration under cyclic changes of pore pressure are revealed and related to the reservoir and mechanical properties of rock samples, as well as different fluid saturation. It is shown that cyclic geomechanical treatment can promote significant improvements of flow characteristics of a carbonate rock material.

Efficient energy storage and uvioresistant perovskite solar cells through insulating Y2O2S-based long-lasting phosphor layer

Perovskite solar cells (PSCs) attract widespread attention owing to its extremely high power conversion efficiency (PCE) and low-price fabrication processing. However, the high-power output is merely limited under sunlight illumination and nearly zero at a dark atmosphere, which may potentially hinder the commercial development and outdoor applications. In this work, we introduce an efficient and stable long-lasting phosphor layer, Y2O2S: Eu3+, Ti4+, Mg2+ enabling PSCs to achieve energy-storage function owing to its persistent photoelectric conversion. When sunlight illumination is turned off, the modified devices can still keep current output for 2 h. Besides, the modified devices demonstrate a considerable improvement of PCE, suppressed hysteretic effects, and highly prolonged light stability. The optimized PCE of 20.9% is obtained through elevated light-harvesting, optimized bandgap alignment, and depressed charge recombination provided by the YOS layer. The modified PSCs maintain 83% of their original PCE after aging in UV light for 100 h and retain 78% of their original PCE after 90 days in the oxygen and humid condition. This work represents a novel strategy on obtaining energy storage and uvioresistant PSCs.

Hysteretic effects of meteorological conditions and their interactions on particulate matter in Chinese cities

Particulate matter (PM) has become the main air pollutant in most cities of in China, which greatly threatens the human health. Numerous studies have reported that PM concentrations could be accurately predicted from previous days’ meteorological conditions. However, the hysteretic or lagged effects of meteorological factors on PM concentrations are not clear. In this study, the GeoDetector q statistic method was used to quantify the hysteretic influences of meteorological conditions and their interactions on concentrations of PM2.5 (particles < 2.5 μm in aerodynamic diameter) and PM10 (particles < 10 μm in aerodynamic diameter) and the ratio of PM2.5 to PM10 (PM2.5/PM10) at multiple spatial and temporal scales in China. We found that the temperature, precipitation, and relative humidity had primary impacts on PM2.5 concentrations, PM10 concentrations, and the PM2.5/PM10 ratios, respectively, at both national and annual time scales. At the seasonal time scale, precipitation and relative humidity had hysteretic effects on PM concentrations in spring and summer, respectively. Moreover, precipitation and wind speed were dominant hysteretic factors in autumn and winter, respectively. At the regional scale, the dominant hysteretic effects of meteorological factors showed large variations across all regional subdivisions. The interactions between any two meteorological factors had an enhanced hysteretic effect on PM concentrations compared to a single factor. These findings could help us to develop scientific measures to reduce the emissions of air pollution and improve the performance of air pollution prediction models.

Experimental Control of Macrophage Pro-Inflammatory Dynamics Using Predictive Models.

Macrophage activity is a major component of the healthy response to infection and injury that consists of tightly regulated early pro-inflammatory activation followed by anti-inflammatory and regenerative activity. In numerous diseases, however, macrophage polarization becomes dysregulated and can not only impair recovery, but can promote further injury and pathogenesis, e.g., after trauma or in diabetic ulcers. Dysregulated macrophages may either fail to polarize or become chronically polarized, resulting in increased production of cytotoxic factors, diminished capacity to clear pathogens, or failure to promote tissue regeneration. In these cases, a method of predicting and dynamically controlling macrophage polarization will enable a new strategy for treating diverse inflammatory diseases. In this work, we developed a model-predictive control framework to temporally regulate macrophage polarization. Using RAW 264.7 macrophages as a model system, we enabled temporal control by identifying transfer function models relating the polarization marker iNOS to exogenous pro- and anti-inflammatory stimuli. These stimuli-to-iNOS response models were identified using linear autoregressive with exogenous input terms (ARX) equations and were coupled with non-linear elements to account for experimentally identified supra-additive and hysteretic effects. Using this model architecture, we were able to reproduce experimentally observed temporal iNOS dynamics induced by lipopolysaccharides (LPS) and interferon gamma (IFN-γ). Moreover, the identified model enabled the design of time-varying input trajectories to experimentally sustain the duration and magnitude of iNOS expression. By designing transfer function models with the intent to predict cell behavior, we were able to predict and experimentally obtain temporal regulation of iNOS expression using LPS and IFN-γ from both naïve and non-naïve initial states. Moreover, our data driven models revealed decaying magnitude of iNOS response to LPS stimulation over time that could be recovered using combined treatment with both LPS and IFN-γ. Given the importance of dynamic tissue macrophage polarization and overall inflammatory regulation to a broad number of diseases, the temporal control methodology presented here will have numerous applications for regulating immune activity dynamics in chronic inflammatory diseases.

Sliding mode observer based hysteresis compensation control for piezoelectric stacks

Piezoelectric stacks (PS) are wildly used as actuator mechanism for precise instrument in practical engineering. Nevertheless, hysteretic effect that is carried by the piezoelectric materials can degrade the control performance dramatically. For the purpose of improving the control precision, the problem of hysteresis compensation control for PS system is investigated in this paper. First, in order to compensate the hysteretic effect, two kinds of observers are proposed. The design of the observers has considered external disturbance and the creep effect in PS system. By utilizing Lyapunov function and linear matrix inequalities (LMI) technique, the observers can asymptotically estimate the hysteretic output with [Formula: see text] performance. Second, a hysteresis-compensation based back-stepping controller is established. The design of the controller has considered the observation error, and it has a certain robustness. At last, numerical and experimental simulations are carried out to verify the effectiveness of the proposed methods.

Removal of ochratoxin A from liquid media using novel low-cost biosorbents.

Ground shells of almonds (ALM), hazelnuts (HAZ), walnuts (WAL), and chestnuts (CHE), coconut fiber (COC), spent coffee grounds (COF), and clementine peel (CLE) were used to remove ochratoxin A (OTA) from both water and an ethanol/water mixture (14:86, v/v). Other very efficient adsorbents like wood biochar (BC) and hydrochar (HC) and a humic acid (HA) were also adopted as a comparison. In batch experiments, sorption of OTA from water followed the trend BC (100% removed) > HA > CLE > COC > HC > COF > ALM > HAZ > CHE > WAL (8% removed), whereas sorption of OTA from ethanol/water mixture (14:86, v/v) onto only the raw materials was COC (54% removed) > CLE > HAZ > ALM > COF > CHE > WAL (0.4% removed). The desorption of the toxin from all materials in water was rather low. Afterwards, sorption kinetics and isotherms of OTA onto CLE, COC, and COF were performed. The three materials adsorbed OTA in about 2 h according to a pseudo-second-order kinetic model, thus indicating the occurrence of a chemisorption mechanism. Equilibrium sorption data of OTA onto CLE followed preferentially the Freundlich model, whereas those on COC and COF fitted well both Freundlich and Langmuir isotherms (r > 0.996). The values of Freundlich sorption constants, KFads, for CLE, COC, and COF were 313, 202, and 98 L kg-1, respectively. OTA desorption from each of the three materials showed hysteretic effects. Overall findings of this work suggest that raw plant wastes could be effectively used as biosorbents to abate the level of OTA in liquid media.

Interest rate bands of inaction and play-hysteresis in domestic investment – Evidence for the Euro Area

The interest rate is an important monetary policy tool to steer investment to safeguard price stability. Knowledge about the exact shape of the interest rate-investment nexus is thus decisive for the European Central Bank’s efficacy. This is especially so in the currently observed low interest rate environment. We first present a theoretical framework of the hysteretic impact of changes in the interest rate on macroeconomic investment under certainty and under uncertainty to investigate whether uncertainty over future interest rates in the Euro area hampers monetary policy transmission. In this non-linear model, strong reactions in investment activity occur as soon as changes of the interest rate exceed a zone of inaction, that we call ‘play’ area. Second, we apply an algorithm describing path-dependent play-hysteresis to estimate investment hysteresis using data on domestic investment and interest rates on corporate loans for 5 countries of the Euro area in the period ranging from 2001Q1 to 2018Q1. We find hysteretic effects of interest rate changes on investment in most countries. However, their shape and magnitude differ widely across countries which poses a challenge for a unified monetary policy. By introducing uncertainty into the regressions, the results do not change much which may be due to the interest rate implicitly incorporating uncertainty effects in investment decisions, e.g. by risk premia.

Nonlinear multi-scale dynamics modeling of piezoceramic energy harvesters with ferroelectric and ferroelastic hysteresis

Hysteretic nonlinearities significantly affect the behavior of devices based on piezoelectric materials. The topic has been widely addressed in the actuation framework, as modeling nonlinear effects is crucial for the dynamic control of piezoelectric actuators. Far less studies, however, discuss the role of hysteresis in the dynamic response of piezoelectric energy harvesters, usually adopting phenomenological modeling approaches. In this work, a physics-based model is employed to reproduce—through a probabilistic thermodynamic approach—the process behind hysteresis in piezoceramic transducers, i.e., the switching of dipoles in crystal domains. A multi-scale approach is then adopted in order to comprise hysteretic effects in the dynamic response of a piezoelectric energy harvester, modeled as a SDOF system. Effects of hysteretic nonlinearities on the device behavior are investigated by means of simulations, and a detailed discussion on the role of material parameters is reported. Moreover, a comparison between predictions of two models—with and without hysteresis—is presented.