Search

Marine foundation species are critical for the structure and functioning of ecosystems and constitute the pillar of trophic chains while also providing a variety of ecosystem services. In recent decades, many foundation species have declined in abundance, sometimes threatening their current geographical distribution. Kelps (Laminariales) are the primary foundation species in temperate coastal systems worldwide. Kelp ecosystems are notoriously variable, challenging the identification of key factors controlling their dynamics. Identification of these drivers is key to predicting the fate of kelp ecosystems under climatic change and to informing management and conservation decisions such as restoration. Here, we used in situ data from long-term monitoring programs across 1350 km of coast spanning multiple biogeographic regions in the state of California (USA) to identify the major regional drivers of density of two dominant canopy-forming kelp species and to elucidate the spatial and temporal scales over which they operate. We used generalized additive mixed models to identify the key drivers of density of two dominant kelp species (Nereocystis luetkeana and Macrocystis pyrifera) across four ecological regions of the state of California (north, central, southwest, and southeast) and for the past two decades (2004-2021). The dominant drivers of kelp density varied among regions and species but always included some combination of nitrate availability, wave energy and exposure, density of purple sea urchins, and temperature as the most important predictors. These variables explained 63% of the variability of bull kelp in the northern and central regions, and 45% and 51.4% of the variability in giant kelp for the central/southwest and southeast regions, respectively. These large-scale analyses infer that a combination of lower nutrient availability, changes in wave energy and exposure, and increases in temperature and purple sea urchin counts have contributed to the decline of kelp observed in the last decade. Understanding the drivers of kelp dynamics can be used to identify regional patterns of historical stability and periods of significant change, ultimately informing resource management and conservation decisions such as site selection for kelp protection and restoration.

In a sequential posture selection task, we reuse former motor plans to reduce cognitive planning cost. The resulting persistence in the former posture, termed motor hysteresis, can serve as a proxy for the percentage of motor plan reuse (PoR). A recent study showed a significant drop in PoR if participants were asked to skip every second drawer in a sequential drawer opening task. In the current study, we sought to disentangle four confounded factors that were potentially responsible for this drop in PoR: a change of (1) spatial distance, (2) digit distance, (3) number of drawers, or (4) context (presence of skipped drawers). To this end, two groups of participants were tested in a series of sequential drawer tasks, where each of the four potential influencing factors was varied independently. PoR was calculated as the dependent variable. Participants displayed a hysteresis effect in all ordered tasks, but the PoR was only reduced by an increase in spatial distance. The three remaining factors had no significant effect. This finding indicates that motor planning is only affected by local (spatial) parameters of the task, but not by context factors (digits, skipped drawers) or global parameters such as the number of drawers. [ABSTRACT FROM AUTHOR]

The total harmonic distortion (THD) of grid current and leakage current are significant for transformerless inverters, as they impact power quality, efficiency, and compliance with grid codes. Monitoring and minimizing these currents ensure safe and reliable grid integration of photovoltaic (PV) systems while reducing electromagnetic interference. Therefore, in this paper, the analysis THD of grid current and leakage current is described. The bipolar pulse width modulation (BPWM) technology provides a stable common-mode voltage (200 V), fewer leakage currents (< 30 mA), and better system efficiency, compared to the unipolar pulse width modulation (UPWM) technique. To ensure the inverter complies with the IEC 61000-3-2 class C (THDi < 5%), the current control strategy should be considered during the design of the transformerless inverter. Therefore, this paper presents an implementation and evaluation of the bipolar hysteresis current control (BHCC) technique. In comparison to the BPWM technique, the BHCC technique delivers lower leakage current (0.007274 A), reduced grid current harmonic distortion (1.81%), and increased efficiency. [ABSTRACT FROM AUTHOR]

Co3Sn2S2, a ferromagnetic Weyl semi-metal with Co atoms on a kagome lattice, has generated much recent attention. Experiments have identified a temperature scale below the Curie temperature. Here, we find that this magnet keeps a memory, when not exposed to a magnetic field sufficiently large to erase it. We identify the driver of this memory effect as a small secondary population of spins, whose coercive field is significantly larger than that of the majority spins. The shape of the magnetization hysteresis curve has a threshold magnetic field set by the demagnetizing factor. These two field scales set the hitherto unidentified temperature scale, which is not a thermodynamic phase transition, but a crossing point between meta-stable boundaries. Global magnetization is well-defined, even when it is non-uniform, but drastic variations in local magnetization point to a coarse energy landscape, with the thermodynamic limit not achieved at micrometer length scales. [ABSTRACT FROM AUTHOR]

The core subunits of the KV7.2, KV7.3, and KV7.5 channels, encoded by the KCNQ2, KCNQ3, and KCNQ5 genes, are expressed across various cell types and play a key role in generating the M-type K+ current (IK(M)). This current is characterized by an activation threshold at low voltages and displays slow activation and deactivation kinetics. Variations in the amplitude and gating kinetics of IK(M) can significantly influence membrane excitability. Notably, IK(M) demonstrates distinct voltage-dependent hysteresis when subjected to prolonged isosceles-triangular ramp pulses. In this review, we explore various small-molecule modulators that can either inhibit or enhance the amplitude of IK(M), along with their perturbations on its gating kinetics and voltage-dependent hysteresis. The inhibitors of IK(M) highlighted here include bisoprolol, brivaracetam, cannabidiol, nalbuphine, phenobarbital, and remdesivir. Conversely, compounds such as flupirtine, kynurenic acid, naringenin, QO-58, and solifenacin have been shown to enhance IK(M). These modulators show potential as pharmacological or therapeutic strategies for treating certain disorders linked to gain-of-function or loss-of-function mutations in M-type K+ (KV7x or KCNQx) channels. [ABSTRACT FROM AUTHOR]

In this work, we analyze the thermodynamic principles underlying modern data storage systems, including Random Access Memory (RAM), hard disk drive (HDD), flash memory, magnetic RAM (MRAM), ferroelectric RAM (FeRAM), and phase-change RAM (PCRAM), as well as other less well-known data storage mechanisms. The analysis is conducted in the context of data storage and processing in relation to Landauer's principle, with special emphasis on hysteresis. Analogous to how heat engines are characterized by thermodynamic cycles, data storage systems are examined in terms of the hysteresis loop of their fundamental data unit. We explore the role of heat in data storage systems. Afterward, we introduce the concept of temperature gradient memory (TeGraM) along with a detailed layout of a realizable device. Experimental results demonstrating this technology are also presented. [ABSTRACT FROM AUTHOR]

Nowadays, owing to declining birthrates and an aging population, patients and the elderly requiring rehabilitation are not getting enough physical activity. In addressing this issue, devices for rehabilitating them have been researched and developed. However, rehabilitation devices are almost exclusively used for patients who can get up, rather than those who are bedridden. In this study, we aim to develop a rehabilitation device that can provide passive exercise for bedridden patients. The ankle joint was selected as the target joint because the patients who have undergone surgery for cerebrovascular disease remain bedridden, and early recovery in the acute stage is highly desirable. We proposed and tested a fan-shaped pneumatic soft actuator (FPSA) that can expand and bend stably at angles when supply pressure is applied as an actuator for a rehabilitation device to encourage patient exercise. However, the previous FPSA's movement deviates from the arch of the foot owing to increased supply pressure. In the ideal case, FPSA should push the arch of the foot in an arc motion. This study proposes and tests the FPSA that can operate a bending motion to provide passive exercise to the ankle joint using tensile springs and a winding mechanism powered by a servo motor. The proposed FPSA has a significant advantage of exhibiting no hysteresis in its pressure-displacement characteristics. The configuration and static analytical model of the improved FPSA are described. [ABSTRACT FROM AUTHOR]

This paper proposes two position control methods for a double air chambers pneumatic artificial muscle (W-PAM) developed to improve the hysteresis characteristics of the rubber-less artificial muscle and confirms their characteristics and usefulness. The proposed control methods are the external pressure-regulated position feedback control and the internal pressure-regulated position feedback control. Of the two air chambers in the W-PAM, the air chamber regulated by the feedback control is different. The steady-state characteristic and frequency characteristics of these controls were compared, and it was experimentally confirmed that the adjusted position feedback control is superior in terms of position control performance. On the other hand, we confirmed that external pressure-regulated position feedback control can express passive stiffness, which is an important characteristic of pneumatic artificial muscles. These results indicate that the W-PAM is a useful actuator for human coexistence systems, because it can express both positional control performance and softness by using different control methods depending on the application. [ABSTRACT FROM AUTHOR]

Monitoring creatinine levels in urine helps to recognize kidney dysfunction. In this research, we developed a photocurable membrane for the detection of serum creatinine. Using a system based on field-effect transistors, we carried out creatinine quantification in synthetic urine. The device was able to cover values between 3 and 27 mmol L−1. The current sensitivity was 0.8529 (mA)1/2 mmol−1 L with 91.8% linearity, with the LOD and LOQ being 5.3 and 17.5 mmol L−1, respectively. The voltage sensitivity was 0.71 mV mmol−1 L with a linearity of 96.2%, with the LOD and LOQ being 4.2 and 14.0 mmol L−1, respectively. These data were obtained under flow conditions. The system performed very well during the measurements, with a hysteresis of about 1.1%. Up to 90 days after manufacture, the sensor still maintained more than 70% of its initial response. Even when used periodically during the first week and then stored unused at −18 °C, it was able to maintain 96.7% of its initial response. The device used in the flow setup only had a useful life of three days due to membrane saturation, which was not reversible. In the interference test, the membrane was also shown to respond to the urea molecule, but in a different response window, which allowed us to discriminate urea in synthetic urine. EGFETs can be used to identify variations in the creatinine concentration in urine and can help in therapeutic decision-making. [ABSTRACT FROM AUTHOR]

The AC conductivity, complex impedance, and power loss (Pcv) in the Ta2O5-doped Mn-Zn ferrites have been comprehensively investigated. In the high-frequency range, AC conductivity increases remarkably with increasing frequency. It has been found that the traditional loss separation method underestimates eddy current loss (Pev) and overestimates residual loss (Prv) due to no consideration of the frequency influence on the conductivity. Based on the analysis of AC conductivity, the generation mechanism of Pev in the high-frequency range has been clarified and the loss separation method has been modified. The loss separation method could be more accurate to guide the development of low-Pcv Mn-Zn ferrites for high-frequency applications. The Ta2O5 addition effectively reduces all three parts of the loss, hysteresis loss (Phv), Pev , and Prv, and the Mn-Zn ferrite with low Pcv in the frequency range of 1–3 MHz has been developed. The optimal sample shows Pcv at 30 °C as low as 15, 65, and 359 kW/m3 at 1 MHz/30 mT, 2 MHz/30 mT, and 3 MHz/30 mT, respectively. The mechanism of Ta2O5 addition influence on Phv and Prv has also been clarified. [ABSTRACT FROM AUTHOR]

Oil palms (Elaeis guineensis Jacq.) are increasingly cultivated throughout the humid tropics and are reported to have high transpiration rates. A potential contribution of stem water storage to transpiration has been discussed in previous studies. We assessed the water-use characteristics of oil palms at different horizontal and vertical positions in the plant by using three sap flux techniques, i.e., thermal dissipation probes, the heat ratio method and heat field deformation sensors. In a radial profile of the stem, sap flux densities were low at the outer margin, increased to 2.5 cm under the bark and remained relatively high to the innermost measured depth at 7.5 cm. In a vertical profile of the stem and with further sensors in leaf petioles, we found only small time lags in sap flux densities. Time lags along the flow path are often used for analyzing the contribution of water storage to transpiration. Thus, the small observed time differences in our study would leave only little room for the contribution of water storage to transpiration. However, water storage might still contribute to transpiration in ways that are not detected by time lag analysis. Such mechanisms may be explored in future studies. [ABSTRACT FROM AUTHOR]

This study presents an experimental analysis of a turbocharger with semi-floating ring bearings, focusing on hysteresis in subsynchronous vibrations. Four automotive oils (SAE 0W-20, SAE 0W-30, SAE 5W-30, SAE 5W-40) were tested across six oil inlet temperatures from 20 °C to 120 °C during ramp-up and ramp-down cycles to examine the effects of lubricant viscosity and temperature on rotor dynamics. Hysteresis and bifurcation points were observed at distinct rotational speeds in both directions, with subsynchronous components providing insights into rotor–lubrication interactions. This study applies the concept of hysteresis loop width for turbocharger rotors, highlighting its nonlinear dependence on oil temperature, an unexpected and unexplained phenomenon. Additionally, the results suggest that vibration sensors could provide real-time feedback on oil supply conditions, offering potential enhancements for turbochargers and other rotating machinery. [ABSTRACT FROM AUTHOR]

This paper investigated the hysteresis performance of multi-story Y-shaped eccentrically bare braced steel frames with block slit dampers (BSDs). After validating existing models through finite element (FE) analysis, an FE model of Y-shaped eccentrically bare braced steel frames (YEBFs) with BSD (BSD-YEBFs) was established. The influences of different types of BSDs on the hysteresis performance of YEBFs were subsequently analysed, as were the seismic performances of YEBFs with BSD (BSDF) and traditional Y-shaped eccentrically bare braced steel frames (TEBF) under cyclic loading, including the stress failure mode, hysteresis curve, stiffness, strength, and energy dissipation capacity. The results showed that: (1) compared with those of BASE-Y, the ductility coefficients of YEBFs with one level BSD (BSD-1) and two level BSD (BSD-2) increased by 59.57% and 39.47%, respectively, and the lateral bearing capacity decreased by 3.26% and 2.78%, respectively. (2) Compared with those of TEBF, the yield bearing capacity and ultimate bearing capacity of BSDF increased by 3.13% and 11.12%, respectively, and the ductility coefficient increased by 56.7%. Moreover, BSDF possesses higher initial stiffness and more sustained energy dissipation capabilities. [ABSTRACT FROM AUTHOR]

Hysteretic nonlinear elasticity is often observed in consolidated granular media, including concrete, mortar, sandstones, or rocks. Nonlinearity is frequently quantified using Nonlinear Resonant Ultrasonic Spectroscopy (NRUS), which provides tools to define nonlinear parameters for both fast and slow dynamic effects, often observed when analyzing the propagation velocity dependence on strain in such materials. The dependence of these parameters on temperature was studied with the aim of using NRUS to quantify the induced thermal damage; thus, experiments were performed spanning a wide temperature range. However, since most of these materials are used in construction (concrete and sandstone, mostly), it is of interest to understand how sensitive the measured nonlinear parameters are to small environmental temperature fluctuations. In this paper, the dependence on temperature of elastic parameters is investigated, both linear (wave velocity and damping) and nonlinear (the slope and hysteresis of the curves describing the strain dependence of wave velocity and residual conditioning effect on wave velocity), separating the slow from the fast dynamic properties of nonlinearity. The observations reported here denote a different behavior for concrete and Berea sandstone. [ABSTRACT FROM AUTHOR]

This article considers a model of a wind power generation system. It is assumed that the wind torque is transmitted to the generator via a gear. At the same time, the gear itself can have backlash with stochastic parameters. This kind of nonlinearity simulates an inevitable aging and wear of the mechanical parts of wind power generation systems over time. The purpose of the study was to identify a control system that would allow for establishing and maintaining the stability of the desired characteristics. The control system is formalized in the form of a second-order linear system. Numerical experiments demonstrated that the suggested control system is robust to stochastic perturbations resulting from both external and internal factors. [ABSTRACT FROM AUTHOR]

The special band structure of bilayer MoS2 makes it show strong nonlinear optical characteristics in the visible band, which provides a new way to develop visible nonlinear devices. In this paper, we present a theoretical analysis of the optical bistability (OB) in a silver–Bragg reflector structure by embedding bilayer MoS2 at the visible band. The nonlinear OB phenomenon is achieved due to the nonlinear conductivity of the bilayer MoS2 and the excitation of the optical Tamm state at the interface between the silver and the Bragg reflector. It is found that the hysteresis behavior and the threshold width of the OB can be effectively tuned by varying the incident light wavelength. In addition, the optical bistable behavior of the structure can be adjusted by varying the position of the MoS2 inset in the defect layer, the incident angle, and the structural parameters of the spacer layer. We believe the above results can provide a new paradigm for the construction of controllable bistable devices. [ABSTRACT FROM AUTHOR]

Far-from-equilibrium systems can form memories of previous deformations or driving. In systems from sheared glassy materials to buckling beams to crumpled sheets, this behavior is dominated by return-point memory, in which revisiting a past extremum of driving restores the system to a previous state. Cyclic driving with both positive and negative strains forms multiple nested memories, as in a single-dial combination lock, while asymmetric driving (only positive strain) cannot. We study this case in a general model of hysteresis that considers discrete elements called hysterons. We show how two hysterons with a frustrated interaction can violate return-point memory, realizing multiple memories of asymmetric driving. This reveals a general principle for designing systems that store sequences of cyclic driving, whether symmetric or asymmetric. In disordered systems, asymmetric driving is a sensitive tool for the direct measurement of frustration. [ABSTRACT FROM AUTHOR]

Sap flow methods are widely used to estimate water use through transpiration in orchards. This study reports for the first time on pecan tree sap flow properties observed in a micro-irrigated orchard in the southeastern US in 2022 and 2023. This new information regarding sap flow properties of Southeastern pecan trees sheds some insight on how pecan water use responds to environmental conditions. The daily peak in the sap flow density occurs either before or after the peak in diurnal solar radiation. The latter peaks before that of air temperature and vapor pressure deficit while the peaks of air temperature and vapor pressure deficit occur later than that of solar radiation. Seasonally, the largest sap flow density occurred during both the growth stage of early nut sizing in May-July and the growth stage of nut sizing and early kernel filling in July-August. The sap flow density in 2022 was higher than that in 2023 mainly due to higher vapor pressure deficit that year. While a single anticlockwise loop of hysteresis occurred in the sap flow diurnally varying with solar radiation in 2023, a twin loop of hysteresis of sap flow to solar radiation was observed in 2022. The twin loop happened since the sap flow peak occurred earlier than that of solar radiation, possibly attributed to high morning vapor pressure deficit that year. A single clockwise loop hysteresis was present in both years in the response of sap flow to air temperature and vapor pressure deficit. The hysteretic strength of the sub-diurnal sap flow density against the vapor pressure deficit for the Southeastern pecan is quantified using a hysteresis index. The index is correlated positively with vapor pressure deficit. This suggests that the drier the air, the greater difference for pecan tree sap flow (or transpiration) in the afternoon to be smaller than that in the morning at the same vapor pressure deficit. [ABSTRACT FROM AUTHOR]

This paper addresses the mechanical characteristics of a passive earth pressure problem taking into account water retention curve (SWRC) hysteresis. Both hydraulic (drying and wetting cycles) and mechanical hysteresis were considered. Parametric studies were carried out at various air entry values (AEV = 5–30 kPa), different wall frictions (δ = 0, 0.33 ϕ, 0.5 ϕ, 0.67 ϕ and δ = ϕ), and unsaturated conditions (covering the zone from the fully saturated to the transition suction, 0 - ~40 kPa) using an upper bound theorem. The numerical results were compared with a passive earth pressure equation based on the limit equilibrium method. The results indicated significant influences of SWRC hysteresis and wall frictions on the passive thrust (Pp) for the modeled suction profiles. An increase of 1.31-fold in Pp was obtained when the AEV changed from 10 to 20 kPa at the water table (Hw) = -2 m. Additionally, the combined effects of AEV and δ were found to be significant. An increase of 4.14-fold in Pp at Hw = -3 m was obtained when comparing the case of AEV = 30 kPa and δ = ϕ with AEV = 5 kPa and δ = 0. Based on the parametric studies, a series of design charts of the exerted passive thrust were proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] Investigating solid–liquid interactions to determine advancing and receding contact angles, and consequently contact angle hysteresis, is crucial for understanding material wetting properties. A reliable, automated, and possibly open-source tool is desirable, to standardize and automatize the measurement and make it user-independent. This study introduces an open-source software, DropenVideo, as an extension of Dropen. DropenVideo automates frame-by-frame video analysis for the advancing and receding contact angle determination, by considering needle presence, contrast tuning, and compensating for missing drop edge data. Contact angles are calculated using convolution mask, circle, and polynomial fittings. An innovative feature in DropenVideo is the automatic protocol for identifying advancing and receding contact angles: (i) the advancing contact angle is determined as the average value during drop inflation; and (ii) the receding contact angle is determined from the frame of incipient motion during drop deflation. Exploring the application of DropenVideo across a range of complex surfaces as representative test cases, we highlight existing challenges in interpreting wetting measurements by addressing different wetting scenarios. Our study demonstrates that employing frame-by-frame automatic analysis of contact angle measurement videos using DropenVideo significantly mitigates the potential risks of subjective bias associated with manual interpretation and enhances the precision of identified wetting characteristics. [ABSTRACT FROM AUTHOR]

The asymptotic behavior of solutions to nonlinear partial differential equations is an important tool for studying their long-term behavior. However, when studying the asymptotic behavior of solutions to nonlinear partial differential equations with delay, the delay factor u (t + θ) in the delay term may lead to oscillations, hysteresis effects, and other phenomena in the solution, which increases the difficulty of studying the well-posedness and asymptotic behavior of the solution. This study investigates the global well-posedness and asymptotic behavior of solutions to the non-autonomous Navier–Stokes equations incorporating infinite delays. To establish global well-posedness, we first construct several suitable function spaces and then prove them using the Galekin approximation method. Then, by accurately estimating the number of determining nodes, we reveal the asymptotic behavior of the solution. The results indicate that the long-term behavior of a strong solution can be determined by its values at a finite number of nodes. [ABSTRACT FROM AUTHOR]

The small-strain shear modulus and shear strength are mechanical parameters crucial in the design of geotechnical structures and in the analyses of soil-structure interactions. This paper proposes a new approach for estimating these mechanical parameters. The proposed approach is predicated on the proportional inverse relationship of mechanical soil properties to the soil-water characteristic curve. The proposed equations supporting the approach incorporate a scaling function, alongside the initial saturated mechanical property. The performance of the proposed equations was demonstrated across a variety of soil textures, utilizing literature soils subjected to varying net normal stresses, and across a wide range of matric suction up to the residual suction zone. It was established that a correlation existed between the scaling function and air-entry value for both small-strain shear modulus and shear strength of unsaturated soils. In addition, the behavior of the scaling function under potential hysteretic effects was demonstrated and recommendations were provided on how to apply the proposed model under such conditions. Finally, the modified equations including the correlation for the scaling function were used to predict additional literature soils. [ABSTRACT FROM AUTHOR]

Space payloads in orbit are vulnerable to small vibrations from satellite platforms, which can degrade their performance. Traditional methods typically involve installing a passive vibration isolation system between the platform and the payload. However, such systems are usually effective only for high-frequency, large-amplitude vibrations and perform poorly in isolating low-frequency vibrations and resonances below 10 Hz. To address this limitation, this paper proposes an active vibration isolation system using a 6-degrees-of-freedom Stewart platform driven by piezoelectric actuators. First, the characteristics of the Stewart platform are analyzed and modeled, with the deformation displacement of each leg calculated through decoupling, allowing for high-precision servo control. Next, given the inherent hysteretic nonlinearity of piezoelectric ceramics, which significantly affects positioning accuracy, the hysteresis mechanism of the actuators is analyzed, and a phenomenological mathematical model based on Bouc–Wen operators is established. A Modified particle swarm optimization (MPSO) method is proposed for identifying the model's nonlinear parameters, significantly enhancing the optimization efficiency. Finally, feedforward inverse compensation and feedback linearization methods are introduced. Experimental results verify that the designed active–passive vibration isolation system greatly improves both the positioning accuracy of the piezoelectric actuators and the active vibration isolation performance of the platform. [ABSTRACT FROM AUTHOR]

Macrophages undergo polarization, resulting in distinct phenotypes. These transitions, including de-/repolarization, lead to hysteresis, where cells retain genetic and epigenetic signatures of previous states, influencing macrophage function. We previously identified a set of interferon-stimulated genes (ISGs) associated with high lipid levels in macrophages that exhibited hysteresis following M1 polarization, suggesting potential alterations in lipid metabolism. In this study, we applied weighted gene co-expression network analysis (WGCNA) and conducted comparative analyses on 162 RNA-seq samples from de-/repolarized and lipid-loaded macrophages, followed by functional exploration. Our results demonstrate that during M1 hysteresis, the sustained high expression of Marco (SR-A6) enhances lipid uptake, while the suppression of Abca1/2 reduces lipid efflux, collectively leading to elevated intracellular lipid levels. This accumulation may compensate for reduced cholesterol biosynthesis and provide energy for sustained inflammatory responses and interferon signaling. Our findings elucidate the relationship between M1 hysteresis and lipid metabolism, contributing to understanding the underlying mechanisms of macrophage hysteresis. [ABSTRACT FROM AUTHOR]

This study proposed a new low-rise bolt–steel plate connection precast concrete sandwich wall structure (PCSWS). Shake table testing was conducted on an experimental model of the bolt–steel plate connection PCSWS with two stories. The experimental phenomenon, failure pattern, displacement response, dynamic characteristics, and global hysteresis were analyzed in detail. The test results revealed that the proposed structure demonstrated excellent seismic performance without any structural cracks when subjected to an excitation intensity level of IX for Model-1. The seismic damage was moderate with no significant structural cracks after an excitation intensity level of IX for Model-2. Cracks in Model-2 occurred in the sequence of the places at the bottoms of the columns, the door corners, window opening corners, and the filled surfaces in the bolt–steel plate connection joint zone on the first floor. The observed damage states were primarily light and moderate, indicating the structure's ability to withstand seismic events. [ABSTRACT FROM AUTHOR]

Magnetorheological (MR) fluid (MRF) dampers, serving as fail-safe semi-active devices, exhibit nonlinear hysteresis characteristics, emphasizing the necessity for accurate modeling to formulate effective control strategies in smart systems. This paper introduces a novel stop operator-based Prandtl-Ishlinskii (PI) model, featuring a reduced parameter set (seven), designed to estimate the nonlinear hysteresis properties of a large-scale bypass MRF damper with variable stiffness capabilities under varying applied current. With only seven parameters, the model realizes current, displacement, and rate dependencies. The force-displacement and force-velocity responses of the designed MRF damper were experimentally characterized under broad ranges of applied current (0–2 A), excitation frequency (0.5–4 Hz), and displacement amplitude (1–2.5 mm). A training dataset was subsequently used to develop a novel field-dependent modified PI model, incorporating multiple hysteresis operators with and without a friction element. The proposed model accurately predicted the MRF damper behavior within the training dataset, and its validity was assessed against data from diverse experimental conditions. The PI model with friction element generally outperformed the model without friction when frequency exceeds 0.5 Hz, demonstrating its ability to characterize nonlinear hysteresis force-displacement and force-velocity properties of the MRF damper under the ranges of applied current and excitations considered with reasonable accuracy. Experimental data were also estimated by the Bouc–Wen model, and compared with those obtained via the formulated PI model, affirming the overall superiority of the proposed PI models considering the computational cost, and total number of parameters. Leveraging the simplicity, minimal parameter requirements, and analytic invertibility of PI models, the proposed PI model is considered a superior choice for modeling and subsequently controlling smart structures employing MRF dampers. [ABSTRACT FROM AUTHOR]