Mode Switching Research Articles

A coupled model to analyse dynamic behaviour of non-prismatic rotating anisotropic thin-walled beams

The current research presents a dynamically coupled mathematical model considering the energy method and employing the classical Ritz-approximation method for a thin-walled anisotropic tapered rotating box beam. The novelty of this work lies in presenting the effect of circumferentially uniform stiffness (CUS) ply layup to investigate the reverberations of not considering bending-shear couplings toward vibration behavior. The current model is formulated by considering transverse shear and cross-sectional warping of order primary and secondary. The repercussions of not including non-classical effects like Coriolis-force, centrifugal-acceleration and warping, inertial-warping is explored. Mode switching arising for change in geometry and centrifugal stiffening is presented for various ply angles and rotational speeds.

Self-learning Markov prediction algorithm based aging-oriented gradient drop power control strategy for the transient modes of fuel cell hybrid electric vehicles

The power transients caused by switching from drive mode to brake mode in fuel cell hybrid electric vehicles (FCHEV) can result in significant degradation cost losses to the fuel cell. To address this issue, this study proposes a self-learning Markov prediction algorithm based aging-oriented gradient drop power control strategy. First, a real-time self-learning Markov predictor (SLMP) based on the traditional offline training Markov improvement is designed to predict the demand power and combined with the sequential quadratic programming (SQP) optimization algorithm to solve for the inner optimal demand power based on its global cost function minimization characteristic. On this basis, the fuel cell gradient drop power (FGDP) strategy is proposed to optimize the operating state of the vehicle powertrain under vehicle mode switching. This involves establishing a power gradient drop step based on considering the fuel cell hydrogen consumption cost and its lifetime degradation cost to further obtain the outer fuel cell demand power at the optimal step. And three execution modes are designed to trigger the FGDP strategy. Finally, by combining the above efforts, the SLMP-FGDP optimization control strategy is constructed. The numerical verification and hardware in loop experiments results show that the proposed improved SLMP can predict the vehicle demand power more accurately. Compared with the non-FGDP system, the SLMP-FGDP strategy can effectively near-eliminate the fuel cell power transient due to any braking scenario, thus effectively controlling the fuel cell lifetime degradation cost in a lower range and realizing a reduction of up to 52.21% of the fuel cell usage costs without significantly sacrificing the hydrogen fuel economy.

Observer-based control of uncertain nonlinear Markovian jump systems with time-varying delay and actuator failures via sliding mode technique

This paper focuses on the discussion of asynchronous sliding mode control (SMC) design for uncertain Markovian jump systems (MJSs) in which nonlinearities, time-varying delays, and actuator failures are considered. At first, the study establishes an asynchronous observer and correspondingly constructs a sliding mode switching function in which the controller gain operates asynchronously with the original system. Then the observer-based SMC law is designed through Lyapunov stability theory to achieve reachability of the specified sliding surface, resulting in mean-square stability of the closed-loop system. In addition, we extend the aforementioned findings to a more practical case where the conditional probability is only partially known. Eventually, numerical examples and tunnel-diode-circuit examples are provided to demonstrate the merits of the summarized results.

An adaptive fuzzy coordinated control strategy for hybrid electric vehicles considering clutch wear and engine temperature variation

AbstractAn improved method of clutch coordinated control based on the Kalman filter was proposed to solve the problem that the existing mode switching strategy of hybrid electric vehicles could not adapt to engine temperature changes and clutch wear. First, taking advantage of the relationship between the torque transmitted by the clutch and the starting resistance of the engine, combined with the characteristics of the clutch, the clutch wear was roughly calculated. Accordingly, the control strategy of the clutch in the existing mode switching was improved to adapt to the clutch wear. The adaptive control strategy proposed for clutch wear included the fuzzy control module of the initial engagement pressure, the fuzzy inference module of the clutch engaging pressure change, the clutch wear estimation module and so on. Second, the Kalman filter was used to process the results to improve the estimation accuracy of clutch wear. The engine starting resistance related to starting speed and temperature was modeled to enhance the adaptability of the control strategy to engine temperature. Finally, the designed control strategy was verified in simulation. The results show that the improved control strategy can complete the mode switching when the engine temperature is variable and the clutch is worn. The maximum impact degree increased from 5 m/s3 without wear to 8.5 m/s3 with wear, but it is still less than the index limit, and it can be considered that the proposed strategy can achieve the desired control effect. The fuzzy control algorithm proposed enhances the vehicle's ride comfort during mode switching from pure electric driving to hybrid driving.

Review of Photovoltaic–Battery Energy Storage Systems for Grid-Forming Operation

Coordinated control technology attracts increasing attention to the photovoltaic–battery energy storage (PV-BES) systems for the grid-forming (GFM) operation. However, there is an absence of a unified perspective that reviews the coordinated GFM control for PV-BES systems based on different system configurations. This paper aims to fill the gap by providing a comprehensive review of coordinated GFM control strategies for PV-BES, considering various system configurations. Typical configurations of PV-BES systems are explored, followed by a detailed discussion of conventional GFM control methods used in the PV-BES systems. Furthermore, coordinated GFM controls are analyzed in PV-BES systems based on different configurations, providing the common DC bus configuration as a widely adopted configuration due to its more control degrees of freedom and ease of expansion. Moreover, the mode division and switching coordinated control based on the system power is the most widely used. Furthermore, challenges in the coordinated GFM controls for the PV-BES system in future applications are briefed and emphasized before the conclusion.

The receptor VLDLR binds Eastern Equine Encephalitis virus through multiple distinct modes

Eastern Equine Encephalitis virus (EEEV) is an alphavirus that can cause severe diseases in infected humans. The very low-density lipoprotein receptor (VLDLR) was recently identified as a receptor of EEEV. Herein, we performed cryo-electron microscopy structural and biochemistry studies on the specific interactions between EEEV and VLDLR. Our results show that VLDLR binds EEEV at three different sites A, B and C through its membrane-distal LDLR class A (LA) repeats. Site A is located in the cleft in between the E1-E2 heterodimers. Site B is located near the connecting β ribbon of E2 and is in proximity to site A, while site C is on the domain B of E2. The binding of VLDLR LAs to EEEV is in complex modes, including the LA1-2 and LA3-5 mediated two major modes. Disruption of the LA1-2 mediated binding significantly affect the cell attachment of EEEV. However, the mutation W132G of VLDLR impairs the binding of LA3, drives the switch of the binding modes, and significantly enhances the attachment of EEEV to the cell. The W132G variant of VLDLR could be identified in human genome and SNP sequences, implying that people with similar mutations in VLDLR may be highly susceptible to EEEV infection.

Modeling and Experimental Study of Vibration Energy Harvester with Triple-Frequency-Up Voltage Output by Vibration Mode Switching.

Conventional wireless sensors rely on chemical batteries. Replacing or charging their batteries is tedious and costly in some situations. As usable kinetic energy exists in the environment, harvesting vibration energy and converting it into electrical energy has become a hotspot. However, the power output capability of a conventional piezoelectric energy harvester (PEH) is limited by its low operational frequency. This paper presents a new mechanism for achieving continuous triple-frequency-up voltage output in a PEH. The proposed system consists of a slender piezoelectric cantilever with two short cantilever-based stoppers. The piezoelectric cantilever undergoes a pure bending mode without contacting the stoppers. In addition, the beam switches into a new vibration mode by contacting the stoppers. The vibration modes switching yields reverses the signs of voltage outputs, inducing triple-frequency-up voltage output. Analytical and experimental investigations are presented, and it is shown that a significant triple-frequency up-conversion of the voltage output can be obtained over a wide frequency range. A peak power output of 3.03 mW was obtained. The proposed energy harvester can support a wireless sensor node.

Asynchronous control for nonlinear switched stochastic delayed systems with weighted mode‐dependent average dwell time

AbstractThis article investigates the asynchronous control for a class of nonlinear switched stochastic delayed systems. In response to this issue, the weighted mode‐dependent average dwell time is first applied to switched stochastic systems as a more general switching signal. In addition, the asynchronous phenomenon is considered to address the mismatch in practical applications, where “mismatch” means the switching of the controllers has a delay to the switching of system modes. Then by selecting new multiple Lyapunov–Krasovskii functionals, sufficient conditions for mean‐square exponential stability and an performance are derived. Finally, numerical examples are provided to illustrate the effectiveness of the proposed methods.

HS-AFM single-molecule structural biology uncovers basis of transporter wanderlust kinetics.

The Pyrococcus horikoshii amino acid transporter GltPh revealed, like other channels and transporters, activity mode switching, previously termed wanderlust kinetics. Unfortunately, to date, the basis of these activity fluctuations is not understood, probably due to a lack of experimental tools that directly access the structural features of transporters related to their instantaneous activity. Here, we take advantage of high-speed atomic force microscopy, unique in providing simultaneous structural and temporal resolution, to uncover the basis of kinetic mode switching in proteins. We developed membrane extension membrane protein reconstitution that allows the analysis of isolated molecules. Together with localization atomic force microscopy, principal component analysis and hidden Markov modeling, we could associate structural states to a functional timeline, allowing six structures to be solved from a single molecule, and an inward-facing state, IFSopen-1, to be determined as a kinetic dead-end in the conformational landscape. The approaches presented on GltPh are generally applicable and open possibilities for time-resolved dynamic single-molecule structural biology.

Post-failure deformation mode switching in volcanic rock.

Beyond a threshold applied compressive stress, porous rocks typically undergo either dilatant or compactant inelastic deformation and the response of their physical properties to deformation mode is key to mass transport, heat transport and pressure evolution in crustal systems. Transitions in failure modes-involving switches between dilatancy and compaction-have also been observed, but to date have received little attention. Here, we perform a series of targeted mechanical deformation experiments on porous andesites, designed to elucidate complex post-failure deformation behaviour. By investigating a sample suite and effective pressure range that straddles the transition between positive and negative volumetric responses to compression, we show two post-failure critical stress states: a transition from compaction to dilation ( ), and a transition from dilation to compaction, which we term . We demonstrate that multiple switches in deformation mode can be driven by stress application under conditions relevant to the shallow crust. While the effect on fluid flow properties of compaction-to-dilation switching may be masked by a net reduction in sample porosity, samples that underwent dilatant-to-compactant failure mode switching exhibited an increase in permeability of approximately two orders of magnitude, despite only slight net volumetric change. Such a substantial permeability enhancement underscores the importance of post-failure deformation in influencing solute and heat transfer in the crust, and the generation of supra-hydrostatic fluid pressures in volcanic environments.

A novel etiology for automatic mode switching and ventricular noise reversion alerts: pulsed field ablation

A novel etiology for automatic mode switching and ventricular noise reversion alerts: pulsed field ablation

Mass transfer and round-trip efficiency evaluation of unitized regeneration proton exchange membrane fuel cell during bi-directional mode switching cycle

Bi-directional mode switching is a crucial operation in unitized regenerative proton exchange membrane fuel cells (UR-PEMFC). Mass transfer plays a direct role in influencing the performance of both the fuel cell (FC) mode and the electrolytic cell (EC) mode, consequently impacting the round-trip efficiency (RTE). This study enhanced the three-dimensional two-phase model of UR-PEMFC by incorporating the mass transfer dynamics of the flow field. The round-trip efficiency (RTE) was systematically assessed throughout the bidirectional mode switching cycle. The results indicate that UR-PEMFC with triple-serpentine flow fields (TSF) performed well in FC mode, which was attributed to its good oxygen distribution uniformity and liquid water detachment capacity, in EC mode, its poor effective mass transfer coefficient and higher mass transfer resistance led to higher electrolytic energy consumption. However, UR-PEMFCs with TSF and parallel flow field (PFF) had better dynamic response performance during the bidirectional mode switching, and their voltage undershoot (overshoot) and response time were improved, which were attributed to uniform flow field structures. The UR-PEMFC reached optimum RTE operating at 0.1 A/cm2 in FC mode and 1.1 A/cm2 in EC mode, and the RTEs of the UR-PEMFCs with PFF and TSF were more advantageous, their highest RTEs were 36.62% and 36.30%, respectively. This study proposes two switching strategies to enhance the stability of URFC mode switching, offering a viable new approach for optimizing the flow field and improving overall performance.

Beamforming design for Star-RIS assisted secure wireless communication system under hardware impairments

Simultaneous transmission and reflection reconfigurable intelligent surface (Star-RIS) has been recently introduced as one of the hopeful technologies in future communications. In this work, we investigate a beamforming design for Star-RIS-assisted secure wireless communications with two practical protocols, namely energy splitting (ES) and mode switching (MS). We assume that our transceivers are not ideal and have residual hardware impairments that lead to distortion noise. We aim to maximize the total secrecy rate by optimizing the beamforming in BS and Star-RIS under the limitation of transmission power consumption. The proposed non-convex optimization problem is solved via successive convex approximation and alternating optimization.

Online learning MPC for switched systems with performance dependent mixed switching law

This paper explores online learning model predictive control (MPC) for switched systems with stable terminal constraints. In order to reduce the computational burden, we decompose the infinite horizon MPC into n finite horizons, and adopt adaptive dynamic programming (ADP) to assist MPC in online solving the optimal control problem in each finite horizon. Further, we use a set of stable terminal constraints to ensure both the convergence of online learning MPC in each finite horizon and the connection of adjacent finite horizons. In addition, in order to ensure the uniform ultimate boundedness (UUB) of the triggered switched systems, on the one hand, a novel performance dependent mixed switching law (PD-MSL) is proposed to both avoid frequent switching and take advantage of performance dependent decision-making; on the other hand, an analytical framework of the coupling between mode switching and event-triggering is proposed. Finally, the validity of the presented approach is demonstrated through simulations.

An octave tuning range quad-core VCO using a multi-mode resonator

This paper presents a novel multi-core multi-mode electric-magnetic (E-M) mixed-coupling voltage-controlled oscillator (VCO), achieving wide tuning range and phase noise optimization simultaneously through a multi-core structure. A symmetric multi-mode resonator is proposed to address the issue of differential signal mismatch caused by transformer asymmetry. An inductor ring is used to balance the inductance of each mode and its effect in each mode is analyzed in detail. A symmetrical switch network is employed for mode switching, offering advantages such as reduced parasitics and mismatch. The utilization of a varactor combined with a fixed capacitor enables electrical coupling, ensuring overlapping frequency bands even with variations in process, voltage, and temperature (PVT), and extending the tuning range. Furthermore, a switched resistor array is employed to bias the negative resistance pair and minimize the contribution of 1/f noise upconversion to the phase noise. Designed in a 40-nm complementary metal–oxide–semiconductor (CMOS) technology with a core area of 0.16 mm2, the VCO achieves a simulated continuous tuning range of 81.5%, spanning from 11.1 to 26.4 GHz. Operating at a 1.1 V supply with a power consumption of 16 mW, the phase noise at 12.15 GHz is −118.6 dBc/Hz at a 1 MHz offset, corresponding to a figure-of-merit (FoM) of 188.3 dBc/Hz and a FoMT of −206.3 dBc/Hz.

Disulfide-Driven Charge and Hydrophobicity Rearrangement of Remodeled Membrane Proteins toward Amyloid-Type Aggregation.

As a common pathological hallmark, protein aggregation into amyloids is a highly complicated phenomenon, attracting extensive research interest for elucidating its structural details and formation mechanisms. Membrane deposition and disulfide-driven protein misfolding play critical roles in amyloid-type aggregation, yet the underlying molecular process remains unclear. Here, we employed sum frequency generation (SFG) vibrational spectroscopy to comprehensively investigate the remodeling process of lysozyme, as the model protein, into amyloid-type aggregates at the cell membrane interface. It was discovered that disulfide reduction concurrently induced the transition of membrane-bound lysozyme from predominantly α-helical to antiparallel β-sheet structures, under a mode switch of membrane interaction from electrostatic to hydrophobic, and subsequent oligomeric aggregation. These findings shed light on the systematic understanding of dynamic molecular mechanisms underlying membrane-interactive amyloid oligomer formation.

Grid-Forming Control for Solar Generation System with Battery Energy Storage

Solar generation systems with battery energy storage have become a research hotspot in recent years. This paper proposes a grid-forming control for such a system. The inverter control consists of the inner dq-axis current control, the dq-axis voltage control, the phase-locked loop (PLL) based frequency control, and the DC voltage control. The proposed control embeds the PLL into the grid-forming inverter control, offering the advantages of better synchronization and fault current-limiting capability. With the proposed control, the battery energy storage is able to provide inertial and primary frequency support during the grid frequency disturbance. Simulation models are established in PSCAD/EMTDC, and the results during the active power variation and AC voltage variation, the grid frequency disturbance, grid fault, and mode switch validate the effectiveness of the proposed control.

Dynamic analysis of cracked pipe elbows: Numerical and experimental studies

This study aims to investigate the dynamic behaviors of fluid-delivering cracked pipe elbows (FDCPEs), thereby providing theoretical and methodological guidance for vibration-based crack detection in pipe elbows. Specifically, an efficient spectral element-finite element (SE-FE) based modeling method for the FDCPEs is proposed firstly, which considers fluid-structure coupling and breathing effect. For the SE-FE method, the spectral element (SE) and finite element (FE) are constructed to simulate the healthy straight segments and cracked elbows of the pipe, respectively, and a penalty function method is adopted to simulate interface coupling and breathing effects. Furthermore, the computational accuracy and efficiency of the SE-FE method are verified through numerical and experimental studies. Finally, the effects of the elbow and crack parameters on the dynamic behaviors of FDCPE are analyzed. The results indicate that changes in the bending radius and angle may trigger frequency veering behaviors, leading to in-plane and out-plane vibration mode switching. Moreover, the even-mode harmonics of the stress responses can effectively detect cracks in the elbow. Most importantly, the strength of nonlinearity at different measuring locations can be used to predict the crack location and size.

Fault Handling and Localization Strategy Based on Waveform Characteristics Recognition with Coordination of Peterson Coil and Resistance Grounding Method

To address challenges in locating high-impedance grounding faults (HIGFs) and isolating fault areas in resonant grounding systems, this paper proposes a novel fault identification method based on coordinating a Peterson coil and a resistance grounding system. This method ensures power supply reliability by extinguishing the fault arc during transient faults with the Peterson coil. When a fault is determined to be permanent, the neutral point switches to a resistance grounding mode, ensuring regular distribution of zero-sequence currents in the network, thereby addressing the challenges of HIGF localization and fault area isolation. Fault calibration and nature determination rely on recognizing neutral point displacement voltage waveforms and dynamic characteristics, eliminating interference from asymmetric phase voltage variations. Fault area identification involves assessing the polarity of zero-sequence current waveforms attenuation during grounding mode switching, preventing misjudgments in grounding protection due to random initial fault angles and Peterson coil compensation states. Field experiments validate the feasibility of this fault location method and its control strategy.

STAR-RIS-assisted key generation method in quasi-static environment

In this paper, we introduce a new method to solve the low-entropy problem in a quasi-static environment. We utilize a simultaneous transmission and reflection reconfigurable intelligent surface (STAR-RIS) that transmits and reflects incoming signals to users located on different sides of the surface. Specifically, we design the flow of multi-user channel probing when STAR-RIS is assisted, analyze and derive the analytical expression of the secret key capacity (SKC) of STAR-RIS-assisted system from the perspective of information theory, and finally analyze how to maximize the SKC and sum of all users under three different working protocols of STAR-RIS. The simulation results show that: (1) STAR-RIS can achieve better SKC performance than the conventional reflection/transmission RIS; and (2) the SKC is determined by the number of STAR-RIS elements, correlation coefficient, pilot length and RIS-reflected channel quality, and the time switching protocol can obtain higher SKC than the energy splitting protocol and mode switching protocol.