Mode Switching Research Articles

DFA-mode-dependent stability of impulsive switched memristive neural networks under channel-covert aperiodic asynchronous attacks

This article is concerned with the deterministic finite automaton-mode-dependent (DFAMD) exponential stability problem of impulsive switched memristive neural networks (SMNNs) with aperiodic asynchronous attacks and the network covert channel. First, unlike the existing literature on SMNNs, this article focuses on DFA to drive mode switching, which facilitates precise system behavior modeling based on deterministic rules and input characters. To eliminate the periodicity and consistency constraints of traditional attacks, this article presents the multichannel aperiodic asynchronous denial-of-service (DoS) attacks, allowing for the diversity of attack sequences. Meanwhile, the network covert channel with a security layer is exploited and its dynamic adjustment is realized jointly through the dynamic weighted try-once-discard (DWTOD) protocol and selector, which can reduce network congestion, improve data security, and enhance system defense capability. In addition, this article proposes a novel mode-dependent hybrid controller composed of output feedback control and mode-dependent impulsive control, with the goal of increasing system flexibility and efficiency. Inspired by the semi-tensor product (STP) technique, Lyapunov–Krasovskii functions, and inequality technology, the novel exponential stability conditions are derived. Finally, a numerical simulation is provided to illustrate the effectiveness of the developed approach.

Experimental characterization of the in-plane shear strength of unreinforced masonry walls with damp-proof course and thermal break layer

Due to the highly demanding energy standards in Europe and challenging weather conditions, thermal break elements, such as aerated autoclaved concrete (AAC), have become increasingly popular in modern day residential buildings made of masonry cavity walls. Furthermore, a damp-proof course (DPC) layer is also used on top of the thermal break element to prevent water seeping and eventual entrapment due to capillary action. The presence of an AAC layer and of a DPC can have an adverse effect on the in-plane shear strength of a masonry wall, although information on this is barely available in the existing literature. This study aims at filling that knowledge gap through experimental investigations on traditional masonry walls and composite masonry walls, i.e. with an AAC and a DPC layer. The in-plane shear behaviour is compared between both types of wall specimens on the base of load-displacement curves and observation of failure modes. The capacity of analytical design approaches in predicting the test results has also been assessed. For the tested configurations, it can be concluded that the presence of AAC and DPC makes the failure mode switch from diagonal shear sliding combined with flexural toe crushing to horizontal shear sliding with crushing localized in the AAC layer, associated to a drop of the resistance by 6 to 9% depending on the type of clay units and mortar. The proposed analytical method, derived from EN 1996-1-1, is providing a safe estimate of the test results with a similar level of accuracy for traditional and composite configurations (predicted values in the range of 75 to 86% of the measured values). Finally, the influence of the definition of the compressed length and of the shear span ratio are shortly discussed.

A switched model predictive control with parametric weights-based mode transition strategy for a novel parallel hybrid electric vehicle

In a novel parallel hybrid electric vehicle (HEV) configuration, the transition from pure electric mode to hybrid mode encompasses critical operations such as engine startup, coordinated control of motor and engine torque, and engagement of the clutch. Addressing the intricate challenges associated with enhancing speed tracking performance during and after mode transition, mitigating jerk during mode transition, and minimizing mode transition time, this paper conducts a meticulous analysis of the vehicle configuration and mode transition process. The mode transition process is systematically delineated into four stages, with each stage characterized by the establishment of dynamic models. Subsequently, a mode transition strategy is proposed, leveraging switched model predictive control with parametric weights (SMPC-PW). This controller framework includes the design of two model predictive controllers (MPC) tailored for two pivotal stages, the formulation of a parametric weights pattern based on pre-transition acceleration, and the development of a stage switching strategy to ensure seamless switches between controllers. The efficacy of the proposed strategy is validated through co-simulations in the Simulink and GT-Power environment. The fine-tuning of MPC parameters is grounded in multiple sets of prediction horizons and sampling time simulation results. In comparison to strategies based on MPC and PID under various acceleration scenarios, the SMPC-PW strategy consistently maintains acceleration control below 10 m/s3. It not only achieves superior speed tracking during and after mode transition but also reduces mode switch time by 0.1 s-0.3 s. These compelling results unequivocally demonstrate that the proposed mode transition strategy significantly elevates the quality of mode transition for this specific parallel HEV configuration.

MEMS-metasurface-enabled mode-switchable vortex lasers.

Compared to conventional lasers limited to generating static modes, mode-switchable lasers equipped with adjustable optics significantly enhance the flexibility and versatility of coherent light sources. However, most current approaches to achieving mode-switchable lasers depend on conventional, i.e., inherently bulky and slow, optical components. Here, we demonstrate fiber lasers empowered by electrically actuated intracavity microelectromechanical system (MEMS)-based optical metasurface (MEMS-OMS) enabling mode switching between fundamental Gaussian and vortex modes at ~1030 nm. By finely adjusting the voltage applied to the MEMS mirror, high-contrast switching between Gaussian (l = 0) and vortex (l = 1, 2, 3, and 5, depending on the OMS arrangement) laser modes is achieved, featuring high mode purities (>95%) and fast responses (~100 microseconds). The proposed intracavity MEMS-OMS-enabled laser configuration provides an at-source solution for generating high-purity fast-switchable laser modes, with potential applications ranging from advanced optical imaging to optical tweezers, optical machining, and intelligent photonics.

Research on control sequence of work mode switching for planetary row multi-mode hybrid powertrain system

According to the characteristics of the planetary row hybrid power system, it is an important issue for the system to adopt a reasonable working mode to realize the efficient operation of the hybrid power system in different operating conditions. Paper takes the single-row hybrid system as the research object. To address the complexity of the working model, a self-construction method using vehicle modeling is proposed. State-space equations are developed for each mode, and an objective function model integrating main and sub-mode switching rules is constructed using the DP algorithm. Learning Vector Quantization (LVQ) network clustering extracts mode-switching sequences. Urban and highway cycles (UDDS and HWFET) are chosen as global optimization parameters. The DP algorithm’s global optimization is applied, extracting sequence basis from UDDS and HWFET compound conditions. Utilizing LVQ input data, the main mode’s power demand is divided into 4 sub-mode regions, generating a switching sequence diagram. Joint simulations verify the effectiveness. ECMS control with regular mode switching yields 4.7458 L/100 km fuel consumption under UDDS & HWFET, 5.53% higher than DP optimization. WLTC conditions, with more medium and high-speed operation, consumption is 5.031 L/100 km, offering further optimization potential.

Spatiotemporal Programmability of 3D Chiral Color Units Driven by Ink Spontaneous Diffusion toward Customized Printing.

Blue phase liquid crystals (BPLCs) have exhibited promising applications in 3D flexible displays due to their molecular-level self-assembled chiral structures, fast response, and tunable polarized colors. However, there remain challenges for spatiotemporal programming of 3D chiral color units for BPLC dynamic patterning. Herein, the programmable temporal evolution of micrometer-scale color units and spatial configuration switch of chiral modes are achieved by spontaneous ink diffusion-driven asymmetric lattice deformation in dual-chiral polymer-templated blue phases. Custom-printed colorful patterns are designed by machine learning-assisted parameter optimization, which displays programmable multidimensional encrypted information that incorporates temporal evolving colors (wavelength), spatial distribution (depth), chiral modes (L/R). The quantitative relationship between ink diffusion kinetics and blue-phase dynamic 3D structural optics is established by in situ characterization, finite element analysis, and mathematical geometry modeling. This work provides insights into the microgeometric manipulation of 3D chiral color of BPLCs in the application of information security and self-adaptive indicators.

Tracing long-term commute mode choice shifts in Beijing: four years after the COVID-19 pandemic

The COVID-19 pandemic has brought urban mobility into a new era. This study traces post-pandemic shifts in commute mode switch behaviors and their environmental effects based on an event study design and a mobile phone signaling dataset for Beijing from April 2018 to November 2023. The results show that in the outbreak stage, public transit mode share nosedived, with transit riders 5.11 and 3.75 times more likely to switch to private car and active modes, respectively; in the post-pandemic stage, public transit recovered rapidly and to a large extent, but the increase of private mode dependency persisted, as transit riders were 1.88 times more likely to switch to private cars, and transit riders and car drivers were 1.37 and 1.32 times more likely to adopt active modes, respectively; in the pandemic-free stage, signs of private car dominance began to emerge, as driving habits strengthened and more active travelers resorted to driving, indicating the closing of the window of opportunity to promote low-carbon private transport. This study presents the longest longitudinal tracking of post-pandemic travel mode choice so far. The challenges and opportunities faced by the transportation system are discussed, and policy implications and future research directions are provided.

Novel Burst-Mode Control for Medium-to-Light Load Operation of Dual-Active-Bridge Converters, Achieving Minimum Backflow Power, Zero-Voltage-Switching, and DC Bias Suppression

The dual-active-bridge (DAB) converter is widely used in many applications such as solid-state transformers, multi-port converters, and on-board chargers. Nevertheless, its efficiency degrades significantly under light-load conditions due to high switching and conduction losses. Since a detailed analysis for burst-mode design has not been presented in the literature, effective burst-mode control for the light-load condition is proposed in this paper. In the proposed burst-mode, the regular duty cycle and the burst duty cycle are optimally coordinated to achieve the zero-voltage-switching (ZVS) condition and the minimum backflow power at the same time. Moreover, DC bias current is effectively eliminated in the proposed burst-mode. The switching loss and conduction loss are simultaneously minimized in the proposed burst-mode control. Therefore, the light-load efficiency is significantly improved. The detailed analysis and design procedure are also presented for both buck- and boost-mode operations to deal with widely varying output voltage ranges. The control mode switching condition is determined for achieving the ZVS condition for the whole load condition; thus, the proposed burst-mode control flowchart is presented. A 4 kW DAB converter prototype is built to verify the proposed method and the experiment results show about a 2% increment in efficiency of the proposed method compared to the conventional burst-mode method.

Delay-tolerant hierarchical distributed control for DC microgrid clusters considering microgrid autonomy

A microgrid cluster (MGC) is formed by interconnected geographically adjacent microgrids (MGs), which can effectively improve power supply reliability. To fulfill the requirements of coordination between MGs while exerting the autonomy ability of each MG, this paper proposes a hierarchical distributed control method for DC MGCs with MG autonomous-cooperative mode switching. The proposed method can not only realize the proportional current sharing between the MGs and the voltage regulation of the common bus but also allow MGs to operate in autonomous or cooperative mode by establishing and disconnecting the inter-MG communication links. In addition, considering that the delay of inter-MG communication links affects multiple control links of the proposed control method, a delay-dependent stability analysis method based on Padé approximation and eigenvalue spectrum comparison is proposed. By stability analysis, the time delay margin (TDM) is determined, and the key link that determines the TDM is identified as the observer based on the proportional-integral (PI) consensus algorithm. On this basis, the scattering transformation (ST) is introduced to improve the stability of the observer under delay and thus enhance the TDM of DC MGCs, which is confirmed by stability analysis based on a new system model integrating node variables and edge variables. Finally, the performance of the proposed control method and stability analysis results are verified by hardware-in-loop (HIL) tests and MATLAB/Simulink simulations

Dynamical response in an electromechanical arm driven by temperature-dependent neural circuit

The thermosensitive neurons can detect changes in external temperature, and the external physical information is converted into neural signals. The external temperature is translated into an equivalent electrical stimulus, and the excitability of these neurons is controlled by adjusting the external electrical signal. These neurons exhibit a certain degree of adaptability, inducing appropriate discharge patterns only when subjected to external stimuli within a specific temperature range. Therefore, thermosensitive neurons formed by temperature regulated neural circuits can be used to study signal processing of thermosensitive neurons and control of mechanical arm. A temperature sensing mechanical arm system is constructed based on neural circuits in this article, and the influence of temperature on the dynamic behaviors of a mechanical arm system regulated by thermosensitive neurons is studied. Numerical simulations are performed to research the effect of external stimulation current and temperature on pattern formation. The bifurcation analysis of the membrane potential reveals the conversion in electrical activity and pattern selection. The bifurcation analysis of membrane potential reveals the mode switching of electrical activity and its impact on the displacement of the mechanical arm. The results indicate that as the temperature changes, the membrane potential exhibits different discharge patterns, which in turn affect the maximum displacement of the mechanical arm. The coupling between neural circuits and mechanical arm promotes effective signal propagation in the system. It is found that there is an appropriate temperature range that allowed the mechanical arm of the coupled system to move steadily back and forth. The research results confirm that external temperature can affect the firing mode of neurons and control the displacement of the mechanical arm.

Abstract 4119167: Electromagnetic Interference from Electric Vehicles: Implications for Subcutaneous Implantable Cardioverter-Defibrillators

Background: Electromagnetic interference (EMI) refers to signals discernible by a device’s circuitry, potentially resulting in erroneous sensing, pacing, mode switching and defibrillation. EMI poses potential risks to the functionality of cardiac implantable electronic devices, with Subcutaneous- Implantable Cardioverter-Defibrillators (S-ICDs) potentially more susceptible due to their design. Research Question: Does EMI from Electric Vehicles (EV) interfere with the functionality of S-ICDs? Goals: Developing and utilizing a loop antenna device that mimics S-ICDs to assess the susceptibility of S-ICDs to EMI from EVs in different charging conditions. Methods: A loop antenna device mimicking the S-ICD lead design was developed, and then validated by the Food and Drug Administration, to detect electromagnetic signals. The device was positioned at different locations in a Tesla Model 3 to measure electromagnetic signals. Results: Statistical analysis revealed a significant difference (p-value < 0.0001) in detected voltage (400-504 mV) around the cup holder compared to all other measured locations. These signals fell within the R-Wave Spectrum of 30-300 Hz. Conclusion: We identified EV-emitted EMI capable of disrupting S-ICD functionality. Further in-vivo studies are essential to determine the level of interference between S-ICDs and EMI from EVs.

Demonstration of normally OFF beta-gallium oxide monolithic bidirectional switch for AC switching applications

In this work, we report on the beta-gallium oxide (β-Ga2O3) monolithic bidirectional switch. The as-fabricated switch works on enhancement mode operation with a threshold voltage of ∼4 V. Maximum drain current density of 1.93 mA/mm is obtained with a drain voltage of 5 V. The bidirectional switch in a bidirectional mode has an ON/OFF current ratio of ∼107 with ON-resistance of 1.11 and 1.09 kΩ · mm in forward and reverse direction, respectively. However, in diode mode, the device shows an ON/OFF current ratio of 1.6 × 108 and 1.4 × 108 in forward and reverse conduction modes, respectively. The fabricated β-Ga2O3 monolithic bidirectional switch is then used to chop a 60 Hz Alternating Current signal at a chopping frequency of 1 kHz, indicating its potential applications in a range of converters.

An Anti‐Attack Neural Sliding Mode Framework Based on a Novel Non‐Fragile Observer

ABSTRACTThis article investigates anti‐attack stabilization with passivity problem of uncertain singular semi‐Markov jump systems (singular S‐MJSs) with exogenous disturbance and delay. An ingenious non‐fragile observer‐based neural sliding mode control (SMC) scheme is put forward to solve the problem. First, considering unmeasured states, a distinctive non‐fragile and decoupled observer, which does not contain the control input or any auxiliary sliding mode compensator design as in existing observer‐based SMC approaches, is established such that the disadvantages of sliding mode switching in observers in existing literature can be avoided. Then, “only one sliding surface” design and a new system analysis route are presented, and the derived sliding surface is accessibly designed. Next, a new version of stochastic admissibility and passivity sufficient condition is given, and a related algorithm via an optimization problem is proposed to determine the controller gain and the observer gain by linear matrix inequalities (LMIs). Further, a novel observer‐based anti‐attack neural SMC law, which utilizes a neural network‐based approach to approximate actuator attack, is proposed to stabilize the singular S‐MJSs against actuator attack. Finally, simulation and comparison results are presented, which demonstrate the effectiveness and superiority of our method.

Comparative Analysis and Improvement of Generalized Droop Control and Virtual Synchronous Generator for Rate of Change of Frequency Constraint and Transient Power Suppression

ABSTRACTSince the microgrid lacks inertia compared to the conventional grid with synchronous generators, the microgrid is unable to address the frequency change issues resulting from the integration of large‐scale distributed generation. Due to the ability to provide virtual inertia, generalized droop control (GDC) and virtual synchronous generator (VSG) control are considered effective solutions for improving frequency regulation. However, in response to external frequency disturbances, the grid‐connected inverters may experience a significant transient active power overshoot caused by GDC and VSG. In this paper, the GDC is used as the fundamental control architecture, and then the small signal models of the GDC and VSG are compared and analyzed under various disturbances. A reduced‐order method for the GDC model is proposed to simplify the analysis of GDC. Additionally, GDC adaptive inertia (GDCAI) and adaptive inertia for operation mode switching (AIOMS) are proposed to mitigate frequency fluctuations and improve active power response. The effectiveness of the two control strategies is verified by MATLAB/Simulink simulation and StarSim hardware‐in‐the‐loop (HIL) experiment.

Research on Energy Management Technology of Photovoltaic-FESS-EV Load Microgrid System

This study focuses on the development and implementation of coordinated control and energy management strategies for a photovoltaic–flywheel energy storage system (PV-FESS)-electric vehicle (EV) load microgrid with direct current (DC). A comprehensive PV-FESS microgrid system is constructed, comprising PV power generation, a flywheel energy storage array, and electric vehicle loads. The research delves into the control strategies for each subsystem within the microgrid, investigating both steady-state operations and transitions between different states. A novel energy management strategy, centered on event-driven mode switching, is proposed to ensure the coordinated control and stable operation of the entire system. Based on the simulation results, the PV system cannot cope with the load demand power when it is increased to a maximum of 2800 W, the effectiveness of the individual control strategies, the coordinated control of the subsystems, and the overall energy management approach are confirmed. The main contribution of this research is the development of a coordinated control mechanism that integrates PV generation with FESS and EV loads, ensuring synchronized operation and enhanced stability of the microgrid. This work provides significant insights into optimizing energy distribution and minimizing losses within microgrid systems, thereby advancing the field of energy management in DC microgrids.

Ultra-Low Threshold Resonance Switching by Terahertz Field Enhancement-Induced Nanobridge.

Ongoing efforts spanning decades aim to enhance the efficiency of optical devices, highlighting the need for a pioneering approach in the development of next-generation components over a broad range of electromagnetic wave spectra. The nonlinear transport of photoexcited carriers in semiconductors at low photon energies is crucial to advancements in semiconductor technology, communication, sensing, and various other fields. In this study, ultra-low threshold resonance mode switching by strong nonlinear carrier transport beyond the semi-classical Boltzmann transport regime using terahertz (THz) electromagnetic waves are demonstrated, whose energy is thousands of times smaller than the bandgap. This is achieved by employing elaborately fabricated 3D tip structures at the nanoscale, and nonlinear effects are directly observed with the THz resonance mode switching. The nanotip structure intensively localizes the THz field and amplifies it by more than ten thousand times, leading to the first observation of carrier multiplication phenomena in these low-intensity THz fields. This experimental findings, confirmed by concrete calculations, shed light on the newly discovered nonlinear behavior of THz fields and their strong interactions with nanoscale structures, with potential implications and insights for advanced THz technologies beyond the quantum regime.

Effect of morphed trailing edge on the acoustic and flow characteristics of National Advisory Committee for Aeronautics (NACA) 4418 airfoil

Trailing-edge profile has an important impact on the aeroacoustic behavior of an airfoil, particularly the tonal noise in the low-medium Reynolds number range. Three profiles, NACA 4418 defined by the National Advisory Committee for Aeronautics (NACA) and its morphed variants with the trailing-edge deflections at ±8°, are investigated by wind tunnel experiments to reveal the acoustic and flow characteristics at the chord-based Reynolds number ranging from 1.2×105 to 3.1×105. The consistent observation across all profiles is the dominant feedback loop located on the pressure surface. The aeroacoustic findings show that the morphed trailing edge alters the tonal frequency spacing, mainly due to the change of the vortex convection velocity in the feedback loop. Furthermore, the trailing-edge morphing is observed to modulate the mode switching of the dominant tones. The local flow results reveal that the laminar separation bubble on the pressure side amplifies the flow oscillation. Notably, the profile with the trailing-edge upward deflection, characterized by a laminar separation bubble on the pressure surface, is particularly susceptible to the low-frequency broadband oscillation. The joint analysis of the acoustic and flow fields suggests that the laminar separation bubble heightens the sensitivity of the dominant tone mode switching to the incoming flow velocity.

Research on control strategy of electric vehicle thermal management system motor

Abstract The low efficiency and difficulty in low-temperature heating are the challenges currently faced by the thermal management system of new energy vehicles. A multi-heat source vehicle thermal management system for waste heat cascade recovery and utilization was proposed, and the performance of the vehicle thermal management system was studied through a combination of component testing and one-dimensional simulation. Based on a one-dimensional simulation model, the characteristics of the motor waste heat source are analyzed. The increase in the inlet water temperature of the motor coolant will lead to enhanced heat dissipation of the motor to the air, resulting in a waste of motor waste heat. Based on the results of the analysis, an energy cascade management strategy is constructed. The optimal heating mode is selected by collecting temperature signals such as motors, and the cut-off valve is controlled through logic gates to achieve flexible switching of different modes. The system effectively reduces the energy consumption of thermal management systems, which is of great significance for developing thermal management systems for new energy vehicles.

The Effect of Intramolecular Proton Transfer on the Mechanism of NO Reduction to N2O by a Copper Complex: A DFT Study.

DFT calculations were performed to explore the mechanism underlying the reduction of NO to N2O by a CuI complex. A nitrosyl complex reacts with another NO molecule and the CuI complex, leading to the formation of a dicopper-hyponitrite complex (Cu2N2O2). The first steps follow a common pathway until the formation of the intermediate [CuII-N2O2]+, after which the reaction pathway diverges into three Cu2N2O2 species: κ2-N,N', κ2-O,O', and κ3-N,O,O'. These species yield different products along their respective reaction pathways. In the case of the κ2-N,N' and κ3-N,O,O' species, the subsequent steps involve a methanol-mediated proton transfer and N-O bond cleavage, resulting in the generation of N2O and [CuII-OH]+. Conversely, for the κ2-O,O' species, two proton transfers occur without N-O bond cleavage, leading to the formation of H2N2O2 and [CuII]2+. H2N2O2 spontaneously converts into N2O and H2O. These computational results elucidate how the coordination mode of hyponitrite influences reactivity and provide insights into NO reduction via proton transfer. Notably, switching of the N2O2 coordination mode to metal ions from N to O was not required, offering insights for more efficient NO reduction strategies in the future.

Quantized feedback stabilization of impulsive switched linear systems based on event triggering

AbstractThis article studies the feedback stabilization problem of an impulsive switched linear system whose feedback loop is closed over a digital network. Particularly, the combined effects of mode switches, impulses, quantization, network delay and external disturbances on the stability of that system are investigated. By extending the previous delay‐free and impulse‐free methods of reachable‐set approximation and propagation, some novel communication and control policies are designed to stabilize the concerned switched system with both network delay and impulses. In order to save the occupied network bandwidth, some event‐triggered control policies are proposed. To handle the effects of the mode switches and the impulse, we design event‐triggering conditions for both the case with no switch and no impulse on an inter‐event interval and the case with one switch or one impulse on an inter‐event interval. Note that the occurrence of a mode switch or an impulse leads to the switch of the event‐triggering conditions. Under the event‐triggered control policies, a stabilizing bit rate condition is derived. It is proven that even under impulses and network delay, the event‐triggered control policies can stabilize the switched system at a lower bit rate than earlier works based on conventional time‐triggered control policies.