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Flow hysteresis in a channel with a supercritical flow in the vicinity of a spindleshaped bridge foundation (SSBF) with a change in flow rate has been investigated in a laboratory for the first time. Two spindle-shaped bridge foundations with diameters of 9 and 6.5 cm, which are placed at distances of 1.5 and 1 meter from the gate, have been used. The critical depth ranges between 0.027 and 0.0528 meters, and the used flow rates range from 250 to 600 liters/min. The flow regimes in the vicinity of the bridge foundations are classified based on the relative depths and Froude numbers created in sections B and C according based on the Froude number at the vena contracta. Sections B and C are near the bridge foundation and the flow passing through the center of the bridge foundation, respectively. The increase and subsequent decrease in velocity leads to different flow states. In some cases, two different behaviors can be seen from the flow with similar laboratory conditions. Hysteresis manifests in the range of Froude number 2.697~5.0. As the bridge foundations approach the valve, the hysteresis area becomes wider. Changes in the flow regime under the same conditions, called hysteresis, should be considered in designs. Also, with hysteresis, the relative residual energy and the downstream Froude number increased by 57.36% and 72.31%, respectively. [ABSTRACT FROM AUTHOR]

Flow hysteresis in a channel with a supercritical flow in the vicinity of a spindle-shaped bridge foundation (SSBF) with a change in flow rate has been investigated in a laboratory for the first time. Two spindle-shaped bridge foundations with diameters of 9 and 6.5 cm, which are placed at distances of 1.5 and 1 meter from the gate, have been used. The critical depth ranges between 0.027 and 0.0528 meters, and the used flow rates range from 250 to 600 liters/min. The flow regimes in the vicinity of the bridge foundations are classified based on the relative depths and Froude numbers created in sections B and C according based on the Froude number at the vena contracta. Sections B and C are near the bridge foundation and the flow passing through the center of the bridge foundation, respectively. The increase and subsequent decrease in velocity leads to different flow states. In some cases, two different behaviors can be seen from the flow with similar laboratory conditions. Hysteresis manifests in the range of Froude number 2.697~5.0. As the bridge foundations approach the valve, the hysteresis area becomes wider. Changes in the flow regime under the same conditions, called hysteresis, should be considered in designs. Also, with hysteresis, the relative residual energy and the downstream Froude number increased by 57.36% and 72.31%, respectively.

Assessing changes of the mass balance in the Antarctic ice sheet in the context of global warming is a key focus in polar study. This study analyzed the spatiotemporal variation in the Antarctic ice sheet's mass balance, both as a whole and by individual basins, from 2003 to 2016 and from 2018 to 2022 using GRACE RL06 data published by the Center for Space Research (CSR) and ERA-5 meteorological data. It explored the lagged relationships between mass balance and precipitation, net surface solar radiation, and temperature, and applied the random forest method to examine the relative contributions of these factors to the ice sheet's mass balance within a nonlinear framework. The results showed that the mass loss rates of the Antarctic ice sheet during the study periods were −123.3 ± 6.2 Gt/a and −24.8 ± 52.1 Gt/a. The region with the greatest mass loss was the Amundsen Sea in West Antarctica (−488.8 ± 5.3 Gt/a and −447.9 ± 14.7 Gt/a), while Queen Maud Land experienced the most significant mass accumulation (44.9 ± 1.0 Gt/a and 30.0 ± 3.2 Gt/a). The main factors contributing to surface ablation of the Antarctic ice sheet are rising temperatures and increased surface net solar radiation, each showing a lag effect of 1 month and 2 months, respectively. Precipitation also affects the loss of the ice sheet to some extent. Over time, the contribution of precipitation to the changes in the ice sheet's mass balance increases. [ABSTRACT FROM AUTHOR]

A back-contact perovskite solar cell (BC-PSC) has been simulated. The J–V curves were calculated with different degrees of the interfacial recombination, and the characteristics of basic physical phenomena inside the device, including carrier concentration distribution, ion concentration distribution, electric potential change, and carrier recombination rate, have also been investigated. It was found that the effect of the perovskite layer's upper surface (US) interfacial recombination on the hysteresis phenomenon is greater than that of the perovskite layer's lower surface (LS) interfacial recombination. In addition, it has been found that the inverted hysteresis phenomenon occurs in the BC-PSC with the LS interfacial recombination. Moreover, the hysteresis loops corresponding to the US interfacial recombination of the perovskite layer were close to the short-circuit current side, and the hysteresis loops corresponding to the LS interfacial recombination of the perovskite layer were close to the open-circuit voltage side. These results indicate that both of the US and LS interface recombinations in the BC-PSC play a crucial role in the hysteresis phenomenon. [ABSTRACT FROM AUTHOR]

In recent years, hard-magnetic soft (HMS) structures have emerged with meritorious properties for potential applications in many fields, such as soft robotics, wearable devices, and stretchable electronics. Developments in reliable computationally efficient dynamic models of HMS structures, however, are vital not only to gain a better understanding of their magneto-mechanical behaviors but also to design effective control algorithms. This study proposes a time-dependent computationally efficient magneto-viscoelastic model of a cantilever HMS structure subject to an external magnetic field. The Kelvin–Voigt internal energy dissipation model is utilized to accurately capture the nonlinear time-dependent response behavior of the HMS beam subject to large magnitudes of the magnetic field at different frequencies. The Galerkin modal decomposition scheme and Bogacki–Shampine method are used to discretize and solve the proposed model. A 2D finite element (FE) model is further developed to assess the effectiveness of the proposed nonlinear model in terms of computational efficacy and accuracy. Moreover, A hardware-in-the-loop framework is developed to experimentally characterize the deflection responses of the HMS beam to steady as well as harmonically varying magnetic fields. The nonlinear deflection responses of the proposed magneto-viscoelastic model subject to magnetic flux density up to 30 mT showed very good agreements with the measured data and the FE model, while the response saturation occurred under a field exceeding 15 mT . The measured and model responses were further analyzed to obtain time-histories, phase-plane, and hysteretic response characteristics of the structure considering different magnitudes ( 5 - 30 mT ) and frequencies ( 0.25 - 1 Hz ) of harmonic as well complex harmonic variations in the magnetic field. The simulation results from the developed model aligned well with the experimental findings across all considered excitations. Moreover, the computation time varied from approximately 3.2 to 31 s, depending on the number of generalized coordinates used in the modal decomposition. The computation time of the FE model on the same computing platform was in excess of 4700s. [ABSTRACT FROM AUTHOR]

Due to the hysteresis characteristics of electrowetting display, the luminance of the same driving voltage is different in the voltage rising stage and the voltage falling stage. In this paper, a gray distortion correction method for hysteresis characteristics of electrowetting display is proposed. Firstly, by measuring the influence of hysteresis characteristics on the photoelectric curve under different voltage ranges, the hysteresis curve model of electrowetting display was established by fitting the measured data. Based on this, the driving voltage mapping relationship of the same gray scale in different scenes is constructed, and finally the effect of reducing the luminance difference is achieved to reduce the gray distortion. Experimental results show that the proposed scheme can effectively reduce the degree of distortion, and the maximum gray‐scale relative luminance difference is reduced from 20.07% to 0.01%, and the reduction ratio is 99.93%. The relative luminance difference was reduced by 10.84% on average, and the reduction ratio was 80.98%. The oil aperture ratio distortion is reduced from 5.67% to 0.13%, and the reduction ratio is 97.7%. [ABSTRACT FROM AUTHOR]

Assessing changes of the mass balance in the Antarctic ice sheet in the context of global warming is a key focus in polar study. This study analyzed the spatiotemporal variation in the Antarctic ice sheet’s mass balance, both as a whole and by individual basins, from 2003 to 2016 and from 2018 to 2022 using GRACE RL06 data published by the Center for Space Research (CSR) and ERA-5 meteorological data. It explored the lagged relationships between mass balance and precipitation, net surface solar radiation, and temperature, and applied the random forest method to examine the relative contributions of these factors to the ice sheet’s mass balance within a nonlinear framework. The results showed that the mass loss rates of the Antarctic ice sheet during the study periods were −123.3 ± 6.2 Gt/a and −24.8 ± 52.1 Gt/a. The region with the greatest mass loss was the Amundsen Sea in West Antarctica (−488.8 ± 5.3 Gt/a and −447.9 ± 14.7 Gt/a), while Queen Maud Land experienced the most significant mass accumulation (44.9 ± 1.0 Gt/a and 30.0 ± 3.2 Gt/a). The main factors contributing to surface ablation of the Antarctic ice sheet are rising temperatures and increased surface net solar radiation, each showing a lag effect of 1 month and 2 months, respectively. Precipitation also affects the loss of the ice sheet to some extent. Over time, the contribution of precipitation to the changes in the ice sheet’s mass balance increases.

To broaden the stable operating range of hypersonic aircrafts, this work examined the mechanisms of the hysteresis phenomenon for hypersonic inlets under acceleration/deceleration process conditions. Guided by unsteady flowfield simulations on two typical 2D hypersonic inlets with different critical unstart modes of hard unstart and soft unstart, two dominant characteristics of the hysteresis phenomenon during the acceleration/deceleration processes were identified. The first characteristic is that, at the same free-stream Mach number in the hysteresis range, the main separation bubble at the cowl-lip station or the internal contraction section of the inlet during the acceleration process is considerably larger than that induced by the cowl shock wave/boundary layer interaction (SWBLI) during the deceleration process. The second characteristic is that the self-starting Mach number during the acceleration process exceeds the unstart Mach number during the deceleration process. Two mechanisms are proposed to explain such hysteresis. First, in the unstarting flowfield at relatively high incoming Mach numbers, the large-scale separation bubble under the unstarted state stems from the self-coupled SWBLI, instead of the throat blockage or the isolated SWBLI, the dimensionless pressure rise through the self-coupled SWBLI during acceleration is much larger than that of the isolated SWBLI during deceleration. Second, the transition between the unstarted state and the started state in the hysteresis range is, in essence, the conversion between the self-coupled SWBLI and the isolated one. [ABSTRACT FROM AUTHOR]

[Display omitted] • T. obliquus can be cultivated using only nutrients derived from refinery wastes. • The periodic change of IO ratio would cause the hysteresis phenomenon of CA activity. • The new system boasts a lipid productivity 3.08 times that in the single environment. The pollution and transformation of refineries are receiving increasing attention. The carbonic anhydrase in Tetradesmus obliquus was found exhibiting a hysteresis phenomenon in response to periodic changes in the composition of external carbon sources, with a surge in inorganic carbon concentration stressing the carbonic anhydrase activity to increase by 6–9 times. On this basis, a novel three-stage culture system of T. obliquus was proposed, which mainly uses refinery waste as the nutrients. By controlling the nutrient content in the environment, especially the composition of carbon sources, microalgae could sequentially complete rapid biomass accumulation, efficient inorganic carbon assimilation, and oil production. Compared to a single-environment culture system, the biomass yield increased by 1.34 times, the oil content increased by more than 6%, and the oil productivity increased by 2.08 times. Above findings may lay a partial theoretical foundation for the future evolution of traditional refineries towards "fossil–algal-biomass" hybrid refineries. [ABSTRACT FROM AUTHOR]

Perovskite solar cells are an important development direction for future solar photovoltaic technology, with advantages such as low cost and high efficiency. However, they commonly suffer from hysteresis effects, which severely impacts the efficiency and lifespan of the cells. This paper analyzes the mechanism of hysteresis effects and the characteristics of the J-V curve of the cells. From a circuit perspective, this paper proposes a circuit modeling method for the J-V characteristics of hysteresis effects in perovskite photovoltaic cells. By utilizing the dynamic properties of nonlinear capacitors, the hysteresis model of perovskite photovoltaic cells is constructed, and the general expression of the model is derived. This model can simulate common hysteresis curves of different perovskite photovoltaic cells under various conditions. Simulation analysis of parameters' effects on hysteresis effects is conducted using the model. Experimental validation confirms that the circuit model accurately replicates the hysteresis effects observed in individual cells. By finely adjusting parameters, the model can efficiently generate a wide array of hysteresis effects, offering exceptional precision and versatility. This capability facilitates the precise simulation of hysteresis phenomena observed in perovskite photovoltaic cells. • A circuit model simulates the hysteresis effect in perovskite PV cells using nonlinear capacitors, with a general expression derived. • Several types of hysteresis effects can be simulated by adjusting the parameters of this model. • Through the simulation and experimental verification of the model, it is proved that the model has a wide range of application and high accuracy. [ABSTRACT FROM AUTHOR]

A facile post-treatment method named defection-stripping and balanced carrier extraction strategy was used to induce p to n-type transition at CsPbI 2.85 Br 0.15 surface. A high efficiency of over 20.30% and ultra-low hysteresis at record level were achieved in inverted inorganic perovskite solar cells. [Display omitted] • Defection-stripping strategy was used to induce p to n-type transition. • Aminoguanidine hydrochloride (AH) achieves the dual function of surface reconstruction and in-situ passivation. • Inverted devices achieve above 20.30% efficiency and ultra-low hysteresis. Inorganic perovskite solar cells (IPSCs) generally face severe hysteresis phenomenon, which limits their application in tandem solar cells (TSCs). Here we introduced a defect-stripping and balanced carrier extraction strategy to mitigate the hysteresis phenomenon. By applying dynamical spins of aminoguanidine hydrochloride (AH) to the upper surface of the inorganic perovskite, the AH material was distributed in a gradient near the surface, leading to a more appropriate level matching between CsPbI 2.85 Br 0.15 and the PC 61 BM as well as reduced non-radiative recombination. However, the modification material penetrates into the interior of the inorganic perovskite and enhances the effective extraction of electrons, leading to non-equilibrium carrier extraction. The power conversion efficiency (PCE) is then further increased to 20.30% by increasing the concentration of the NiO x hole transport layer (HTL), achieving a record ultra-low hysteresis. [ABSTRACT FROM AUTHOR]

In this paper the problem of vibration reduction is considered. Generally, mechanical vibrations occurring during the operation of a system are undesirable and may have a negative effect on its reliability. A finite element model of a single active blade is developed using the Abaqus software. This structure consists of a multi-layer glass-epoxy composite beam with an embedded macro fiber composite (MFC) piezoelectric actuator. For vibration control the use of a positive position feedback (PPF) controller is proposed. To include the PPF controller in the Abaqus software, a special subroutine is created. The developed control algorithm code makes it possible to solve an additional differential equation by the fourth order Runge- Kutta method. A numerical dynamic analysis is performed by the implicit procedure. The beam responses with and without controller activation are compared. The control subsystem model also includes the hysteresis phenomenon of the piezoelectric actuator. Numerical findings regarding the PPF controller’s effectiveness are verified experimentally. [ABSTRACT FROM AUTHOR]

The main purpose of this paper is to analyze the impact of hysteresis of a piezoelectric subsystem on the nonlinear beam dynamics with active vibration control. The investigated model considers geometric and inertia nonlinearities of the beam (plant), nonlinear coupling of the controller, and hysteresis of the piezoelectric actuator. The developed numerical model of the electromechanical system allows a comparison of responses given by a simplified model and a model with a complete description of the piezoelectric subsystem, including hysteresis. Obtained results provide information about the effect of hysteresis on the beam and controller dynamics. Quantitative and qualitative changes due to considering the effect of hysteresis are presented in the paper. [ABSTRACT FROM AUTHOR]

Hysteresis phenomenon is a distinctive approach to describe the natural behavior of the magnetic materials and magnetic cores. This article proposes a phenomenological approach for core quality assessment and condition monitoring of magnetic cores with grain-oriented electrical steels. The developed technique is based on the hysteresis phenomenon and interpreting the most distinctive parameters of the measured dynamic hysteresis loops. In this study, artificial short circuits were introduced between the laminations of stacks of two, three, and four Epstein size strips of Fe–3 wt % Si grain-oriented steel. The results showed that condition monitoring of the magnetic cores can be effectively performed by measuring and analyzing the hysteresis loops. [ABSTRACT FROM AUTHOR]

In this paper, a new 4D hyperchaotic nonlinear dynamical system with two positive Lyapunov exponents is presented. Exhaustive dynamic analyses of the novel hyperchaotic model using several dynamical studies are described. The dynamics of the system considered are first investigated analytically and numerically to explore phenomena and the selection of hyperchaotic behavior utilized for designing image cryptosystem. Since the proposed hyperchaotic model has rich dynamics, it displays hidden attractors. It emerges from this dynamic the existence of a single unstable equilibrium point giving rise to self-excited attractors, hysteresis phenomenon, and hyperchaotic behavior strongly recommended for securing information by its character. Furthermore, the feasibility and synchronization of the proposed system are also presented by developing, respectively, Raspberry surveys and an adaptive synchronization approach of two identical hyperchaotic systems. By employing the hyperchaotic behavior of the 4D map, an image encryption scheme is proposed as well. It is one round of a pixel-based permutation and a bit-wise diffusion phase. The secret key of the 4D map is derived from the SHA-256 value of the input image. It acts as the signature of the input image. Hence, the secret key exhibits high sensitivity to single-bit alteration in the image, which makes the cryptosystem robust against chosen/known-plaintext attacks. Performance analyses prove that the proposed cryptosystem provides the best in terms of the performance/complexity trade-off, as compared to some recently published algorithms.

Numerous car-following models have been developed since the 1950s. However, there still exist many traffic phenomena that cannot be demonstrated using the existing models. Therefore, this research proposed a new car-following model, the Asymmetric car-following (ACF) model based on the understanding of driver’s asymmetric behavior, which can explain complex traffic phenomena. We established the asymmetric car-following (ACF) rule under the vehicle’s safety constraints using eight parameters that indicate the driver’s characteristics and vehicle’s performances. To evaluate the ACF model, we performed the simulation for car-following pairs and conducted a comparison analysis with the existing models: Newell, Gipps, GM, and IDM. As a result, the proposed ACF model showed good fitness with the empirical trajectory and the apparent asymmetric behavior compared to others. For further investigation in the congested traffic stream, we simulated a group of vehicles by adding an error term to represent the driver’s unexpected behavior. The simulation showed growth, propagation, and dissipation of the stop-and-go traffic. These results proved that the ACF model has the strength to elaborate on various traffic phenomena, such as traffic hysteresis and stop-and-go traffic. [ABSTRACT FROM AUTHOR]

The research work presented is originated with the intent of studying driving behavior, especially in a lateral direction under the influence of construction work activities under prevailing heterogeneous traffic conditions. Initially, a midblock road section is selected, and then macroscopic traffic characteristics were evaluated. Later, Mumbai metro-rail construction work was started on the same road section. As a result, it was planned to study the variation in traffic-flow characteristics for road sections with-and-without construction work zone at microscopic as well as macroscopic levels. For this purpose, video graphic surveys were conducted, and macroscopic characteristics were evaluated for both study sections (with-and-without construction work zone). The results showed that at given flow levels, the stream speeds were dropped from 70 to 50 kph, followed by a drop in efficiency in terms of per-lane capacity. To sense this impact more deeply, vehicular trajectory data were developed over road sections at three different traffic-flow levels. The driving behavior is investigated using different variables, such as longitudinal following behavior, following times, lateral amplitude, and lateral placement, followed by lateral direction correlation analysis. From the investigation, the results show that the following-hysteresis plots for vehicles are found to be slender in a construction work-zone, revealing the conservative approach in driving behavior. Furthermore, following-time analysis also supports the same interpretation. Given the smaller size of vehicles, the vehicle tends to possess extra lateral freedom and hence is responsible for the seeping phenomenon through a porous media in the traffic stream. As an impact of reduced road width, capacity (per-lane) values are found to be higher in the base section than the section having a construction work zone. Further, based on the conceptualized framework, safety in the traffic stream over the study sections was evaluated. Finally, the importance of cautioning drivers the construction work activity in advance was well revealed from the safety analysis of this work. [ABSTRACT FROM AUTHOR]

Highlights • Thermal behavior of micro-encapsulated PCM wallboard. • Effect of heating rate, volume fraction and sample mass on the DSC curves. • Apparent hysteresis phenomenon during phase change process. Abstract An axisymmetric physical model based on the porous medium approach was performed to quantify the thermal gradients inside a building material containing microencapsulated phase change material (PCM) in the differential scanning calorimeter cells. The conservation equations are solved numerically using finite difference method. The general expressions of the specific enthalpy, the apparent heat capacity and the equivalent heat capacity are exposed. The influence of various parameters like the heating/cooling rate, the volume fraction of the PCM and the sample masse on the thermal behavior of these materials is investigated and discussed. Despite the small dimensions of the differential scanning calorimeter samples, important temperature gradients were observed during the phase change process of the PCM. [ABSTRACT FROM AUTHOR]

• The effects of hysteresis were highlighted at several scales. • A new hysteresis implementation method was proposed and validated using a bi-climatic chamber. • Considering the hysteresis phenomenon improved the accuracy of prediction of the developed numerical model. • Significant deviations in relative humidity and heat flux were observed in the habitable ambience between simulation cases. Experimental measurements of sorption isotherms show a difference between the water contents in the adsorption phase and the desorption one. This is mainly due to the hysteresis phenomenon. Not considering this phenomenon in hygrothermal behaviour models impacts the reliability of the latter. In this paper, we have studied the effects of hysteresis on the hygrothermal behaviour at the building scale. For this purpose, a new implementation method of a hysteresis model was proposed and validated at the material and wall scales using a bi-climatic chamber which controlled the indoor and outdoor climate conditions. Then, the effect of the hysteresis phenomenon at the building scale was evaluated following a COMSOL/TRNSYS co-simulation approach to consider the gains and losses in the hydric fluxes going through walls. The results showed significant differences in terms of the relative humidity of the living environment. However, no difference was noticed in the temperature variations. On the other hand, the total heat fluxes were also affected by the hysteresis phenomenon due to latent heat parts, that were driven by variations in relative humidity. The maximum gain and loss discrepancies (with and without hysteresis) in total heat fluxes of 1121 kJ/h and 1086 kJ/h, respectively, were obtained during the first week of February (winter period). The results also revealed that these discrepancies are sensitive to the number of persons in the living environment. [ABSTRACT FROM AUTHOR]

Inter-tube flow pattern of horizontal tube falling film dominates the flow state of thin film around the tube and influences heat transfer. An observation experiment was performed to investigate the inter-tube flow characteristics of horizontal tube falling film focusing on 19 and 25.4 mm-diameter Al-brass tubes with the Reynolds number ranging from 64.4 to 598. The flow pattern images were captured by a high-definition camera and a high-speed camera with backlight method. Flow patterns were characterized and their transitions were classified. Phenomena occurred in flow pattern transition were discussed with the variation of Reynolds number, tube spacing, and tube diameter. The results show that the critical transition Reynolds number increases with tube spacing. Special flow patterns were observed and classified when the tube spacing was undersize. The hysteresis in horizontal tube falling film flow were discussed in detailed. [ABSTRACT FROM AUTHOR]

This paper presents a dynamic modeling and microscopic vibration suppression for a flexible macro-micro manipulator dedicated to high-speed operation. The manipulator system mainly consists of a macro motion stage and a flexible micromanipulator bonded with one macro-fiber-composite actuator. Based on Hamilton's principle and the Bouc–Wen hysteresis equation, the nonlinear dynamic model is obtained. Then, a hybrid control scheme is proposed to simultaneously suppress the elastic vibration during and after the motor motion. In particular, the hybrid control strategy is composed of a trajectory planning approach and an adaptive variable structure control. Moreover, two optimization indices regarding the comprehensive torques and synthesized vibrations are designed, and the optimal trajectories are acquired using a genetic algorithm. Furthermore, a nonlinear fuzzy regulator is used to adjust the switching gain in the variable structure control. Thus, a fuzzy variable structure control with nonlinear adaptive control law is achieved. A series of experiments are performed to verify the effectiveness and feasibility of the established system model and hybrid control strategy. The excited vibration during the motor motion and the residual vibration after the motor motion are decreased. Meanwhile, the settling time is shortened. Both the manipulation stability and operation efficiency of the manipulator are improved by the proposed hybrid strategy. [ABSTRACT FROM AUTHOR]

To design a kind of aerospace vehicle, the drag and heat flux reduction are the most important factors. In the current study, the counterflowing jet, one of the effective drag and heat flux reduction concepts, is investigated numerically by the two-dimensional axisymmetric Reynolds-averaged Navier-Stokes equations coupled with the SST k-ω turbulence model. An axisymmetric numerical simulation mode of the counterflowing jet on the supersonic vehicle nose-tip is established, and the numerical method employed is validated by the experimental schlieren images and experimental data in the open literature. A pulsed counterflowing jet scheme is proposed, and it uses a sinusoidal function to control the total and static pressures of the counterflowing jet. The obtained results show that the long penetration mode does not exist in the whole turnaround, even in a relatively small range of the jet total and static pressures, and this is different from the phenomenon obtained under the steady condition in the open literature. At the same time, it is observed that the variation of the physical parameters, such as the Stanton number induced by the pulsed jet, has an obvious periodicity and hysteresis phenomenon. [ABSTRACT FROM AUTHOR]

Accurate description of absolute adsorption/desorption behavior for hydrocarbons on shale is of critical importance to the understanding of the fundamental mechanisms governing the storage, transport, and recovery of shale gas or shale gas condensate in shale reservoirs. By applying a thermogravimetric method, we first measure the excess adsorption/desorption isotherms of pure CH 4 and n -C 4 H 10 on shale samples over the temperature range of 303.15–393.15 K. The maximum test pressures considered for CH 4 and n -C 4 H 10 are 50 bar and 2 bar, respectively. Grand Canonical Monte Carlo (GCMC) simulations are then applied to calculate the density of the adsorption phase by considering the fluid-pore surface interactions. We use such calculated density of the adsorption phase to calibrate the excess adsorption/desorption isotherms, which enables us to eventually obtain the absolute adsorption/desorption isotherms. Such approach for estimating the density of the adsorption phase is essentially different from the commonly used approaches in which the density of the adsorption phase is considered to be independent of temperature, pressure, and pore size. The adsorption/desorption test results show that both CH 4 and n -C 4 H 10 exhibit more adsorption as temperature decreases or pressure increases. Their adsorption/desorption isotherms exhibit hysteresis phenomenon and this phenomenon weakens as temperature increases. Comparatively, the hysteresis behavior observed for n -C 4 H 10 is more obvious than that for CH 4 . Compared with CH 4 , n -C 4 H 10 has higher adsorption capacity under the same condition , indicating its higher affinity towards the shale with organic matters. As for the conventional approaches, the density calculated from the van der Waals constant b or the liquid hydrocarbon density can be used to reasonably well evaluate the absolute adsorption isotherms of n -C 4 H 10 on shale, but tends to underestimate the absolute adsorption of CH 4 on shale. GCMC simulations show that the density of the adsorption phase is strongly correlated with system pressure, temperature, and pore size. Compared to the conventional approaches, GCMC simulations can better capture the in-situ density of adsorption phase; on the basis of the in-situ density of adsorption phase, we can then achieve more accurate determination of the absolute adsorption isotherms of a given hydrocarbon on shale. This study raises the imperativeness of leveraging more sophisticated simulation tools (such as GCMC) for more accurate determination of absolute adsorption isotherms. [ABSTRACT FROM AUTHOR]

The analysis of nonlinear characteristics and control of mode transition process is the crucial issue to enhance the stability and reliability of the dual-mode scramjet engine. In the current study, the mode transition processes in both strut-based combustor and cavity-strut based combustor are numerically studied, and the influence of the cavity on the transition process is analyzed in detail. The simulations are conducted by means of the Reynolds averaged Navier-Stokes (RANS) equations coupled with the renormalization group (RNG) k-ε turbulence model and the single-step chemical reaction mechanism, and this numerical approach is proved to be valid by comparing the predicted results with the available experimental shadowgraphs in the open literature. During the mode transition process, an obvious nonlinear property is observed, namely the unevenly variations of pressure along the combustor. The hysteresis phenomenon is more obvious upstream of the flow field. For the cavity-strut configuration, the whole flow field is more inclined to the supersonic state during the transition process, and it is uneasy to convert to the ramjet mode. In the scram-to-ram transition process, the process would be more stable, and the hysteresis effect would be reduced in the ram-to-scram transition process. [ABSTRACT FROM AUTHOR]

The battery power capability is intimately correlated with the climbing, braking and accelerating performance of the electric vehicles. Accurate power capability prediction can not only guarantee the safety but also regulate driving behavior and optimize battery energy usage. However, the nonlinearity of the battery model is very complex especially for the lithium iron phosphate batteries. Besides, the hysteresis loop in the open-circuit voltage curve is easy to cause large error in model prediction. In this work, a multi-parameter constraints dynamic estimation method is proposed to predict the battery continuous period power capability. A high-fidelity battery model which considers the battery polarization and hysteresis phenomenon is presented to approximate the high nonlinearity of the lithium iron phosphate battery. Explicit analyses of power capability with multiple constraints are elaborated, specifically the state-of-energy is considered in power capability assessment. Furthermore, to solve the problem of nonlinear system state estimation, and suppress noise interference, the UKF based state observer is employed for power capability prediction. The performance of the proposed methodology is demonstrated by experiments under different dynamic characterization schedules. The charge and discharge power capabilities of the lithium iron phosphate batteries are quantitatively assessed under different time scales and temperatures. [ABSTRACT FROM AUTHOR]

To select the optimal ammonia–water nanofluids and apply to ammonia–water absorption refrigeration systems (AARS), this paper investigated the influence of heating on viscosity, thermal conductivity and absorbance of binary nanofluids. The hysteresis phenomenon was observed after heating at high temperature which is rarely reported in the literature. Experimental results show that most of nanofluids' thermal conductivity increased by about 3–12% after heating. However, their viscosities increased by as much as 15% to 25% except the γ-TiO 2 ammonia–water nanofluid, which was reduced by 2% to 7%. This study also shows that the trend of viscosity is consistent with the absorbance. Due to fact that the thermal conductivity of γ-TiO 2 /NH 3 –H 2 O mixture increased after heating, while the viscosity decreased, even if the concentration of the base liquid is 12.5% or 25%, therefore it is the optimal choice for practical research in AARS at present. [ABSTRACT FROM AUTHOR]

The most commonly used models in geomagnetic‐induced currents (GICs) studies neglect the hysteresis phenomenon. In relation to this, the authors present an approach to integrate the hysteresis phenomenon to the finite‐element model (2D‐FEM) for the effects of the GIC which considers the current, as an input quantity. These currents are obtained by a dynamic electromagnetic model that the authors developed, and are compared with the results obtained by experimentation. This is the first time that this phenomenon has been shown in three‐phase transformers with load. They also provide other practical responses in relation to other papers in which their studies concern the imbalance GIC bias on the asymmetric three‐phase transformers with no‐load while the majority of the transformers operate on load. [ABSTRACT FROM AUTHOR]

The origin of two different hysteresis pheno- mena observed in a few cells of 3-D NAND flash memory with a tube-type poly-Si body was analyzed. To identify the origin, we analyzed the capture and emission property of charges in two different trap sites by measuring devices at various temperature conditions and using fast I–V measurement. It was found that the clockwise hysteresis property is originated from the traps in the tunneling oxide butted to tube-type poly-Si body and the counter-clockwise hysteresis property is originated from the traps in the high- k blocking dielectric. Although the number of abnormal cells with a large hysteresis is much smaller than that of the normal cells, it is confirmed by pulse measurement that these abnormal cells can produce large threshold voltage variations. [ABSTRACT FROM AUTHOR]

From current study the flow states of hypersonic inlet are classified into two types: start and unstart. Between start and unstart exists the double solution region, which forms the classical double solution theory of air inlet. However, because the shock in hypersonic inlet strongly interferes and interconnects with the boundary layer, it is very hard for the classical double solution theory to explain all flow phenomena. Profound study was done to improve understanding of hypersonic inlet and 4 distinct types of flow mode which disrelated with overrating were discovered from experiments, supplemented with CFD calculations. They are flow mode of start, large separation on body (LSB), small separation on body (SSB), and dual-separation on both body and lip (DSBL). The study also found that there is hysteresis phenomenon between the four types of flow mode and that their pairwise combinations produce six types of double solution region. Furthermore, according to the historical status and different entry paths, the study found out three types of triple solution region: "start + LSB + DSBL", "LSB + SSB + DSBL", and "start + SSB + DSBL". The study results not only greatly enrich the theory of hypersonic inlet, but also have great significance in guiding engineering practice of air inlet. [ABSTRACT FROM AUTHOR]

Piezoelectric cantilever actuators are widely used in micro/nano-positioning applications due to their relatively accurate response and large operating bandwidth. One of the main obstacles in the way of implementing high-accuracy position tracking in high frequencies is the piezoelectric hysteresis phenomenon. It is known from previous research that piezoelectric materials exhibit a rate-dependent hysteresis loop. The purpose of this article is to obtain a novel hysteresis model that can accurately describe the output of the piezoelectric actuator. This is done by introducing a hysteresis model in the form of an actuated linear dynamic system. This model provides the ability to capture both rate-dependence and magnitude characteristics of the system, and it is simple and easy to implement in real-time. As a result, the proposed method accurately predicts the position of the piezo-actuated beam in a wide range of input frequencies and amplitudes. To demonstrate its effectiveness, the proposed hysteresis model is used along with a robust control loop to track the position of a piezo-actuated beam plant. It is shown using experimental results that utilizing this model leads to accurate position control in a wide range of frequencies. [ABSTRACT FROM AUTHOR]

Although molecular electronics is in its infancy, many significant advances have been reported in this field and, at present, it is necessary to study different types of materials that are potentially useful in molecular electronics and its properties. Experimental and theoretical studies have shown that almost all nanoscale devices such as molecular devices usually exhibit hysteresis characteristic due to various phenomena such as electron energy discreteness, electron tunneling, Coulomb blockade effects, etc. Some efforts have been made for modeling molecular electronics; however, not all of them support the hysteresis behavior. To the best of the authors’ knowledge, this paper for the first time proposes a general model for modeling the hysteresis behavior in molecular electronics. The proposed model is a HSPICE compatible circuit model and one of its main features is the ability to model both dc and ac behaviors of molecular electronic materials. The model can accept all amplitudes in the definite range, is continuous in the whole range and its parameters have minimum complexity resulting in maximum simplicity in terms of parameter extraction. Correct operation of the proposed circuit model and its accuracy are investigated by applying it to some hysteresis graphs reported in the literature, and the results are shown in this paper. [ABSTRACT FROM PUBLISHER]

Unbonded flexible pipes have complex structural forms and numerous structural parameters. There are different degrees of contact and slip between the structural layers under bending loads, which brings challenges to the structural design and bending characteristics analysis of flexible pipes. In this paper, according to the law of energy conservation and deformation geometry theory, the mechanical equilibrium equation of each layer of unbonded flexible riser under bending load is established and the contact condition between layers is introduced in the first step. According to the slip state of the spiral strip, the response of the flexible riser under bending load was divided into three stages: no slip, partial slip and complete slip. The expressions of bending moment and bending stiffness were derived. The influence of structural parameters of tensile armor layer of unbonded flexible pipes on its bending performance under bending load is studied by using MATLAB software to compile the corresponding calculation program. The results show that the increase of friction coefficient between layers of tensile armor will improve the bending resistance of flexible pipes. The increase of helix angle will reduce the bending stiffness of flexible pipes in the initial stage. The increase of the number of spiral strips will increase the bending stiffness of flexible pipes in the initial stage. In the process of structural design of flexible pipes, the influence of the above structural parameters on the bending characteristics of flexible pipes should be taken into account. • Write a numerical calculation program combined with the mechanical property theory of unbonded flexible pipe section. • Develop a parametric modeling calculation software to accurately calculate the mechanical characteristics of the pipe's section under bending load. Carry out sensitivity analysis on the cross section parameters of the pipe and summarize the rule changes. [ABSTRACT FROM AUTHOR]

Present numerical study attempts to investigate the hysteresis phenomena and different flow patterns of the power-law fluids past two unconfined square prisms arranged in tandem configuration. The convective heat transfer from the bodies is also studied. The gap spacing between the cylinders varies from 1 d to 8 d , where d is the length of each prism side. The simulations are performed for different power-law indexes ( n = 0.7 , 1 a n d 1.6 ) a t R e = 100 , 150 ( P e = 70 , 105 ) . It is observed that the flow patterns of the power-law fluids depend on the gap spacing between prisms. When the gap spacing is varied from 1 d to 8 d , three major flow regimes (single slender body, reattach and co-shedding) are found for the selected power-law indexes at R e = 100 and 150 . Similar to the Newtonian fluid ( n = 1 ) , the hysteresis with two different flow patterns is observed for shear-thinning ( n < 1 ) and shear-thickening ( n > 1 ) fluids in a certain range of the gap lengths, where the hysteresis limit depends on the fluids type and Reynolds number. [ABSTRACT FROM AUTHOR]

This article verifies the hysteresis phenomenon in heat-voltage curves of polypyrrole-coated electrospun nanofibrous and regular fibrous mats. A third-order polynomial model fits the heat-voltage data better than a second-order polynomial model. It was also observed that the hysteresis loop area of nanofibrous and regular fibrous mats increases with decreasing fiber diameter. Moreover, the curvature of the hysteresis loops is significantly affected by the fiber diameter. In fact, the slope of the curvatures increases with decreasing fiber diameter. [ABSTRACT FROM AUTHOR]

Experimental investigations on the dependence of the stability threshold on different operating procedures have been carried out in a uniform diameter rectangular loop with orifice plates. The investigations revealed that there is no unique stability threshold for the different operating procedures with orifice confirming the existence of a hysteresis region just as in the loop without orifice. The hysteresis region can be further categorized into unconditionally stable, conditionally stable and unconditionally unstable regions even with the orifice plates. The stability region is found to increase with the introduction of the orifices. The predicted dimensionless steady state flow rate with orifice is found to be in good agreement with the data. One dimensional linear stability analysis accounting for the effective length of the orifices and elbows have been used to predict the stability map. The 1-D analysis can qualitatively predict the stabilizing effect of the orifice plates. However, the stable experimental data is not well characterized by the stability map predicted by the 1-D linear stability analysis which is attributed to the 3-D nature of the flow, the heat losses and the wall thermal inertia which are neglected in the 1-D analysis. • Dependence of the stability threshold on different operating procedures have been discussed. • The 1-D analysis qualitatively predicted the stabilizing effect of the orifice plates. • The existence of the hysteresis phenomenon is confirmed even with orifice. [ABSTRACT FROM AUTHOR]

Series coupled natural circulation system with the last loop being an open-air loop finds application as an infinite mission time passive decay heat removal system in nuclear power plants and solar thermal systems. Hence the stability behavior of series coupled rectangular loops with horizontal heater and horizontal cooler orientation was experimentally studied. The loop was subjected to various operating procedures viz., start up from rest, power raising from a stable steady state and power step down from an unstable state to witness that the stability threshold was not a unique value, thus confirming the existence of a hysteresis phenomenon. The stability threshold enhancement of the system with orifice plates was maximum for the lowest orifice diameter. The coupled system was chosen with an unstable first loop and the instability was found to transmit from loop#1 to the subsequent loops. However, the oscillation amplitude was highly attenuated and seemed to be nearly stable in the 2nd and 3rd loop without any flow reversals even when the first loop was unstable with chaotic bidirectional pulsing. In case of bi-directional pulsing in loop#1, the heat exchanger between the first two loops operated alternatively in co-current and counter-current mode with no change in the flow direction of loop#2. A delay in the flow initiation was found for start-up from rest, which increased from the first loop to the last loop and decreased with the increase in power input. Further, the numerical simulation with the one-dimensional model reproduced the oscillatory behavior in loop#1, with the predicted stability threshold being considerably lower compared to the experiments. The attenuation of the oscillations in the loop#2 as observed in the experiments could be reproduced. Predicted transients showed practically no oscillations in loop#3 corroborating the experimental observations. The attenuation of the oscillations in loop#2 and the absence of oscillations in loop#3 were attributed to the damping caused by the wall and also due to the higher Lt/D ratio in loop#2 and a vertical air flow channel in loop#3 respectively. The phase plots indicated a near periodic oscillation compared to the highly chaotic pattern in the experiments, presumably due to the higher power at which instability was observed in the experiments. The deviations were also due to the secondary flows being generated in the large diameter loop as the simulation was based on 1D along with the heat loss being neglected. • Stability behavior of coupled natural circulation loop is demonstrated with three loops in series. • Stability threshold dependence on orifice plate and operating procedure is discussed with experiments and numerical studies. • Attenuation of oscillation amplitude is seen across subsequent loops in series. [ABSTRACT FROM AUTHOR]

The effects of temperature and low-volume concentration on the dynamic viscosity of the Al2O3/water and Al2O3/ethylene glycol/water nanofluids are investigated. Nanofluids were prepared and characterised. Data were collected for temperatures ranging from 25 to 80°C. The presence of aggregated Al2O3 nanoparticles in the fluid, with average diameter of 109 nm which is ∼8 times the primary diameter (13 nm) of Al2O3 nanoparticles was witnessed. Furthermore, only at temperature below 40°C water-based alumina nanofluid at 0·05% v/v showed Newtonian behaviour. On the other hand, Al2O3/ethylene glycol/water mixture exhibited Newtonian behaviour. Results clearly showed the presence of a critical temperature, beyond which the particle suspension properties were noticed to be radically changed, which results in activating the hysteresis phenomenon. The hysteresis phenomenon on viscosity measurement, which is believed to be the first observed for ethylene glycol/water-based nanofluids, has raised serious concerns regarding the use of nanofluids for heat transfer enhancement. [ABSTRACT FROM AUTHOR]

In this paper, artificial neural network (ANN) was applied to model and study the signature of hysteresis phenomena in hydrological processes for the Eel River watershed located in California. Because of the nonlinear and stochastic nature of hysteresis phenomena, it is reasonable to expect ANN to develop a model that efficiently considers hysteretic loops. In this study, hysteretic loops were studied from different aspects such as forms, classification, and effective factors of creation. In rainfall-runoff modeling, counterclockwise loops were mostly observed, whereas in the runoff-sediment process, clockwise loops prevailed. Random or eight-shaped loops were expected in runoff hydrographs with several peaks. A direct relationship was detected between the width of the loops and the area of the subbasin. Larger areas led to wider hysteretic loops. The results showed that ANN efficiently considers hysteresis signs when modeling hydrological processes and can lead to appropriate performance. [ABSTRACT FROM AUTHOR]

In this study, the unstart/restart process of a hypersonic inlet caused by the angle of attack (AOA) is experimentally performed at a Mach number of 5.0, and the unsteady flow characteristics during the test are investigated. The flow characteristics are simultaneously recorded using high-frequency pressure measurement and high-speed schlieren imaging. The results show that the inlet enters the unstarting state at AOA = 8.4° but restarts at AOA = 0.3°, exhibiting an obvious hysteresis phenomenon. During the unstart process, the forebody shock gradually approaches the body and then impinges on the inside of the cowl with the increasing angle of attack, indicating that the inlet works under an overrated mode. As the angle of attack increases further, the airflow chokes, and a high-pressure zone is first formed in the exit of the duct. Then, the high-pressure signal propagates upstream in the duct, leading to the emergence of an inlet unstart. When the inlet enters the unstarted pattern, a typical local unstarted flow field is formed. Low-amplitude oscillations occur in the internal contraction region, but further propagation to the isolator is weak. During the restart process, when the angle of attack decreases from 3.2° to 0.3°, two kinds of big buzz patterns, namely, intermittent high-amplitude oscillation and periodic high-amplitude oscillation, appear successively. The intermittent high-amplitude oscillation is characterized by the intermittent occurrence of a high-amplitude oscillation after the low-amplitude oscillations for a random length of time. In the periodic high-amplitude oscillation, the separation bubble is repeatedly disgorged and swallowed, resulting in a dominant fluctuation frequency in the entire duct. Furthermore, as the angle of attack decreases, the dominant frequency gradually rises from 280 Hz to 339 Hz. This work provides new insights into the flow evolutions and unsteady behaviors of hypersonic inlet unstart/restart owing to the AOA and provides potential applications on the detection and prediction of hypersonic inlet unstart/restart. [ABSTRACT FROM AUTHOR]

The flow in a planar overexpanded nozzle with a slope discontinuity is studied numerically by means of two- (2D) and three-dimensional (3D) Reynolds-averaged Navier-Stokes simulations and is compared to experimental results. The nozzle pressure ratios (NPR) vary from 1.6 to 10. A good agreement is found between experimental and numerical results and two configurations are observed: under a certain critical NPR, the flow is shown to be asymmetrical with respect to the nozzle axis, while it is perfectly symmetrical for higher NPRs. The value of the critical NPR is found to be very dependent on the turbulence model. Finally, an hysteresis phenomenon is evidenced since the NPR at which the change of flow configuration occurs is different whether the NPR is increasing or decreasing in the nozzle. [ABSTRACT FROM AUTHOR]

Highlights: [•] Study of current voltage curves of OTFTs with hysteresis and contact phenomena. [•] Compact model for the output characteristics of OTFTs. [•] Parameter extraction method including contact effects and hysteresis. [•] Charge density in the intrinsic channel and the contact and their threshold voltage. [•] Determination of the variation of trapped charge during voltage cycling. [Copyright &y& Elsevier]

In this paper, a new 4D hyperchaotic nonlinear dynamical system with two positive Lyapunov exponents is presented. Exhaustive dynamic analyses of the novel hyperchaotic model using several dynamical studies are described. The dynamics of the system considered are first investigated analytically and numerically to explore phenomena and the selection of hyperchaotic behavior utilized for designing image cryptosystem. Since the proposed hyperchaotic model has rich dynamics, it displays hidden attractors. It emerges from this dynamic the existence of a single unstable equilibrium point giving rise to self-excited attractors, hysteresis phenomenon, and hyperchaotic behavior strongly recommended for securing information by its character. Furthermore, the feasibility and synchronization of the proposed system are also presented by developing, respectively, Raspberry surveys and an adaptive synchronization approach of two identical hyperchaotic systems. By employing the hyperchaotic behavior of the 4D map, an image encryption scheme is proposed as well. It is one round of a pixel-based permutation and a bit-wise diffusion phase. The secret key of the 4D map is derived from the SHA-256 value of the input image. It acts as the signature of the input image. Hence, the secret key exhibits high sensitivity to single-bit alteration in the image, which makes the cryptosystem robust against chosen/known-plaintext attacks. Performance analyses prove that the proposed cryptosystem provides the best in terms of the performance/complexity trade-off, as compared to some recently published algorithms. [ABSTRACT FROM AUTHOR]

Abstract: We study stable equilibria of liquid crystals in the flow being at rest and the stable dynamic states for nematic liquid crystals under weak shear flow for the Doi model [M. Doi, S.F. Edwards, The Theory of Polymer Dynamics, Oxford University Press, 1986]. It is first theoretically proven that there is a hysteresis phenomenon in the flow being at rest when the non-dimensional potential intensity among particles changes. Furthermore, in the weak shear flow, we show that there exist many stable dynamic states: flow aligning, tumbing, log-rolling and kayaking, which depend on the initial concentrated orientation of liquid crystal particles. The results are consistent with those of numerical simulation [M.G. Forest, Q. Wang, R. Zhou, The weak shear kinetic phase diagram for nematic polymers, Rheol. Acta 43 (2004) 17–37; M.G. Forest, R. Zhou, Q.Wang, Full-tensor alignment criteria for sheared nematic polymers, J. Rheol. 47 (2003) 105–127] and experimental discoveries [W.R. Burghardt, Molecular orientation and rheology in sheared lyotropic liquid crystalline polymers, Macromol. Chem. Phys. 199 (1998) 471–488; Ch. Gähwiller, Temperature dependence of flow alignment in nematic liquid crystals, Phys. Rev. Lett. 28 (1972) 1554–1556]. Theoretical analysis is reported the first time that the Kayaking state does not circulate around a fixed direction but the asymmetric axis will periodically change. [Copyright &y& Elsevier]

Abstract: A bifurcation behaviour of flows driven by opposing buoyancy in two vertically connected open cavities was found and investigated using flow visualization experiments, theoretical analysis and computational fluid dynamics simulations. In the theoretical analysis, the fluid in each cavity was assumed to be fully mixed. It was found that two stable fixed points exist for a certain range of strength ratios of the heat source/sink. Hysteresis phenomenon was found between the two stable steady flows. The simple theoretical analysis suggests that two Hopf bifurcations also occur. Both computational fluid dynamics simulations and flow visualization confirm the existence of two stable solutions. [Copyright &y& Elsevier]