Flexible Switching Research Articles

Multi-functional photonic spin Hall effect sensor controlled by phase transition

Abstract Photonic spin Hall effect (PSHE), as a novel physical effect in light–matter interaction, provides an effective metrological method for characterizing the tiny variation in refractive index (RI). In this work, we propose a multi-functional PSHE sensor based on VO2, a material that can reveal the phase transition behavior. By applying thermal control, the mutual transformation into different phase states of VO2 can be realized, which contributes to the flexible switching between multiple RI sensing tasks. When VO2 is insulating, the ultrasensitive detection of glucose concentrations in human blood is achieved. When VO2 is in a mixed phase, the structure can be designed to distinguish between the normal cells and cancer cells through no-label and real-time monitoring. When VO2 is metallic, the proposed PSHE sensor can act as an RI indicator for gas analytes. Compared with other multi-functional sensing devices with the complex structures, our design consists of only one analyte and two VO2 layers, which is very simple and elegant. Therefore, the proposed VO2-based PSHE sensor has outstanding advantages such as small size, high sensitivity, no-label, and real-time detection, providing a new approach for investigating tunable multi-functional sensors.

Adaptive Quasi-Super-Twisting Sliding Mode Control for Flexible Multistate Switch

The mathematical model of a flexible multistate switch (FMSS) exhibits nonlinear and strong coupling characteristics, whereas traditional power decoupling control makes it difficult to completely decouple the output power. The traditional proportional–integral control parameters are difficult to adjust, and their robustness and dynamic performance are poor, which affects the stability of the voltage of the power distribution network and feeder power. To address these problems, this study first converted the original system into a linear system via coordinate transformation using feedback-accurate linearization to decouple active and reactive currents. Thereafter, a super-twisting sliding mode control (ST-SMC) algorithm was introduced, and an adaptive quasi-super-twisting sliding mode control (AQST-SMC) algorithm comprising the quasi-sliding mode function and adaptive proportional term was proposed. An FMSS double closed-loop controller was designed to achieve improved vibration suppression and convergence speed. A three-port FMSS simulation model was developed using MATLAB/Simulink, and the simulation results show that the proposed control strategy enhances the robustness and dynamic performance of the system.

A family of single‐phase boost AC‐AC converters based on impedance network cells with symmetric bipolar operation

SummaryIn this paper, a family of single‐phase boost AC‐AC converters based on impedance network cells with symmetric bipolar operation is proposed. The proposed converters exhibit a range of voltage gains as a result of non‐inverting and inverting boost operations, which are influenced by the input voltage and various impedance source cells. The converters leverage inherent commutation to address the commutation problem without requiring snubber circuits and safe commutation strategy. Additionally, high‐speed switching is achieved by preventing power MOSFETs' body diode conduction and related poor reverse recovery issues. The design incorporates a simple and flexible switching strategy to produce step‐change frequency at the output, using only four switches to achieve both step‐changed frequency operation and output voltage regulation. Furthermore, by reducing the total stored energy of passive components, the proposed converters effectively decrease volume, weight, and cost. The operational modes of the converters are elucidated, and their key relationships are summarized in tabular format. Finally, experimental validation through a laboratory prototype confirms the performance accuracy of the proposed converters at frequencies 25, 50, and 100 Hz.

Wideband-tunable microwave photonic filter using dissipative self-interference microring resonators

We propose and demonstrate a widely tunable microwave photonic filter with controlled frequency agility, bandwidth reconfigurability and flexible switching functions. It is based on the self-interference microring aided by an asymmetric Mach–Zehnder interferometer, breaking the fundamental microring footprint limit and achieving a doubled free spectral range (123.2 GHz) with a strong out-of-band rejection. Simulation results show that a bandpass microwave photonic filter can be tuned across a 60 GHz frequency range with a varied 3-dB bandwidth from 2.13 GHz to 40.7 GHz in a cascaded dual-ring topology. Its RF out-of-band rejection ratio is improved by more than 60 dB in the high frequency region due to a perfect residual phase cancellation. A dual-band notch microwave photonic filter with an extinction ratio of about 50 dB and a frequency tunable range of about 27.7 GHz is also demonstrated, showing its broadly applicability. Our method highlights its suitability to improve chip-scale wideband and high-performance RF receiver systems.

Highly flexible and uniform switching of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)based RRAM achieved through Ag NWs embedded for high-density storage

A super-flexible resistive random access memory (RRAM) based on poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) embedded with Ag nanowires (Ag NWs) is fabricated on a piece of aluminum foil. In the design, the aluminum foil is used as the substrate as well as the electrode, which not only solves the flexibility of the device, but also greatly reduces the volume of the device, helpful to realize high-density integration. The uniformity of the device is greatly improved after the modification of the Ag NWs. The fluctuation range of the Set voltage (Vset) / Reset voltage (Vreset) is reduced from 0.9~2.78 V/ −0.45∼-1.25 V to 1.14∼1.35 V/-1 ∼0.5 V. What’s more, the average Vset / Vreset is decreased from 2.5 V/-1.25 V to 1.2 V/-0.7 V. Also, the multilevel switching potential of the device is confirmed by controlling the reset voltage((-0.5, −0.7, and −1.0 V). After repetitive 1000 bendings of the device with a radius of 6 mm, a stable memory window of more than 103 is still detected during 300 continuous cycles. No degradation is observed from the two resistance states at 85 °C after 104 s. These results clearly demonstrate that the device has a broad application prospect in the future application of flexible electronics due to its simple and thin structure, low cost, excellent flexibility and good uniformity.

A full-duplex 5G mobile fronthaul based on analog RoF-WDM-PON supporting flexible frequency-band switching with colorless and simple RRH

In this paper, a full-duplex analog radio over fiber scheme based on wavelength division multiplexing passive optical network (A-RoF-WDM-PON) is proposed for the 5G mobile fronthaul (MFH). For the downlink, a flexible switching of the frequency-band covering sub-6G and millimeter wave (MMW) is enabled by the combination of a polarization controller and a polarizer. The colorless and simple remote radio head (RRH) is realized by the wavelength reuse and phase modulation of the upstream (US) signal. For the uplink, the high-frequency US signal can be photonic down-converted to an immediate frequency (IF) with the assistance of the 2nd order harmonic of the electrical local oscillator (ELO) and the coherent detection is employed to improve the receiver sensitivity. The proposed scheme is experimentally demonstrated by the transmission of a 100-Msym/s 16-QAM downstream (DS) signal over 25 km single-mode fiber (SMF) and a 100-Msym/s 16-QAM US signal over 10 km SMF. The experimental results show that the error vector amplitudes (EVMs) for downlink at frequency bands of 3.5 GHz, 12.5 GHz and 21.5 GHz are 6.30%, 5.90% and 7.15% respectively. The EVM of US signal at 19 GHz is 7.64%. The EVM performance versus the received optical power for both up- and down-link are also measured. Additionally, a dual-wavelength multiplexing transmission is carried out, the measured EVMs in one wavelength channel are 7.65%, 7.63%, 11.33% and 8.47%, and the EVMs for the other wavelength channel are 8.09%, 7.74%, 11.45% and 8.42%, which meets the standard of the Third Generation Partnership Program (3GPP).

Novel automated training platform for studying flexible switching among natural motivated behaviors in mice

Novel automated training platform for studying flexible switching among natural motivated behaviors in mice

Control method based on DRFNN sliding mode for multifunctional flexible multistate switch

To address the low accuracy and stability when applying classical control theory in distribution networks with distributed generation, a control method involving flexible multistate switches (FMSs) is proposed in this study. This approach is based on an improved double-loop recursive fuzzy neural network (DRFNN) sliding mode, which is intended to stably achieve multiterminal power interaction and adaptive arc suppression for single-phase ground faults. First, an improved DRFNN sliding mode control (SMC) method is proposed to overcome the chattering and transient overshoot inherent in the classical SMC and reduce the reliance on a precise mathematical model of the control system. To improve the robustness of the system, an adaptive parameter-adjustment strategy for the DRFNN is designed, where its dynamic mapping capabilities are leveraged to improve the transient compensation control. Additionally, a quasi-continuous second- order sliding mode controller with a calculus-driven sliding mode surface is developed to improve the current monitoring accuracy and enhance the system stability. The stability of the proposed method and the convergence of the network parameters are verified using the Lyapunov theorem. A simulation model of the three-port FMS with its control system is constructed in MATLAB/Simulink. The simulation result confirms the feasibility and effectiveness of the proposed control strategy based on a comparative analysis.

Smart Energy Storage: W18O49 NW/Ti3C2Tx Composite-Enabled All Solid State Flexible Electrochromic Supercapacitors.

Developing a highly efficient electrochromic energy storage device with sufficient color fluctuation and significant electrochemical performance is highly desirable for practical energy-saving applications. Here, to achieve a highly stable material with a large electrochemical storage capacity, a W18O49 NW/Ti3C2Tx composite has been fabricated and deposited on a pre-assembled Ag and W18O49 NW conductive network by Langmuir-Blodgett technique. The resulting hybrid electrode composed of 15 layers of W18O49 NW/Ti3C2Tx composite exhibits an areal capacitance of 125mFcm-2, with a fast and reversible switching response. An optical modulation of 98.2% can be maintained at a current density of 5mAcm-2. Using this electrode, a bifunctional symmetric electrochromic supercapacitor device having an energy density of 10.26µWhcm-2 and a power density of 0.605mWcm-2 is fabricated, with high capacity retention and full columbic efficiency over 4000 charge-discharge cycles. Meanwhile, the device displays remarkable electrochromic characteristics, including fast switching time (5s for coloring and 7s for bleaching), and a significant coloration efficiency of 116cm2C-1 with good optical modulation stability. In addition, the device exhibits significant mechanical flexibility and fast switching while being stable over 100 bending cycles, which is promising for real-world applications.

Switchable and tunable dual-wavelength thulium-doped fiber laser based on the parallel filter of the all-fiber Sagnac interferometer embedded with an FBG and the Fabry-Perot filter

A switchable and tunable dual-wavelength thulium-doped fiber laser (ST-DW-TDFL) based on the parallel filter is proposed and experimentally demonstrated in this study. In the proposed ST-DW-TDFL, there are two independent branches to form the parallel filter. One branch uses an all-fiber Sagnac interferometer embedded with a fiber Bragg grating (FBG-FSI) as the wavelength selection element, and the other branch uses a Fabry-Perot (FP) filter as the wavelength selection element. By adjusting two optical attenuators to change the light power of two branches, single and dual-wavelength output can be achieved and switched. On the basis of achieving dual-wavelength output, independent and continuous tuning of two wavelengths can be achieved by heating the FBG and adjusting the FP filter. The tuning range of one wavelength is up to 5.84 nm, while the tuning range of the other wavelength is up to 99.86 nm. The maximum wavelength variation and power fluctuation are less than 0.03 nm and 0.5 dB at room temperature. And the experimental results show that the proposed ST-DW-TDFL has flexible wavelength switching and tuning capabilities and good wavelength and power stabilities.

Predicting tail risks by a Markov switching MGARCH model with varying copula regimes

AbstractTo improve the dynamic assessment of risks of speculative assets, we apply a Markov switching MGARCH approach to portfolio risk forecasting. More specifically, we take advantage of the flexible Markov switching copula multivariate GARCH (MS‐C‐MGARCH) model of Fülle and Herwartz (2022). As an empirical illustration, we take the perspective of a risk‐averse agent and employ the suggested model for assessments of future risks of portfolios composed of a high‐yield equity index (S&P 500) and two safe‐haven investment instruments (i.e., Gold and US Treasury Bond Futures). We follow recent suggestions to employ the expected shortfall as a prime assessment of tail risks. To accurately evaluate the merits of the new model, we back‐test the risk forecasting for daily returns over 10 years for heterogeneous market environments including, for example, the COVID‐19 pandemic. We find that the MS‐C‐MGARCH model outperforms benchmark volatility models (MGARCH, C‐MGARCH) in predicting both value‐at‐risk and expected shortfall. The superiority of the MS‐C‐MGARCH model becomes stronger, when the share of comparably risky assets in the portfolio is relatively large.

Vision Transformer-based overlay processor for Edge Computing

Accelerating Visual Neural Networks in Edge Computing environments is crucial for processing image and video data. Visual Neural Networks, including Convolutional Neural Networks and Vision Transformers, are central to image recognition, video analysis, and object detection tasks. Deploying these networks on edge devices and accelerating them can significantly enhance data processing speed and efficiency. The large number of parameters, complex computational flows, and various structural variants of Transformer models present both opportunities and challenges. We propose Vis-TOP (Vision Transformer Overlay Processor), an overlay processor designed for all types of Vision Transformer models. Vis-TOP, distinct from coarse-grained general-purpose accelerators like GPUs and fine-grained custom designs, encapsulates Vision Transformer characteristics into a three-layer, two-level mapping structure, enabling flexible model switching without hardware architecture modifications. Concurrently, we designed a corresponding instruction bundle and hardware architecture within this mapping structure. We implemented the overlay processor design on the ZCU102 after quantizing the Swin Transformer model to 8-bit fixed points (fix_8). Experimentally, our throughput surpasses GPU implementation by 1.5 times. Our throughput per DSP is 2.2 to 11.7 times higher than that of existing Transformer-like accelerators. Overall, our approach satisfies real-time AI requirements in resource consumption and inference speed. Vis-TOP offers a cost-effective image processing solution for Edge Computing on reconfigurable devices, enhancing computational resource utilization, saving data transfer time and costs, and reducing latency.

Dysphagia Intervention in Patient with Diffusion Axon Injury with Bilateral Frontal Lobe Contusion: A Case Report

Introduction: Traumatic brain injury (TBI) is a leading cause of chronic neurologic disability. Damage often affects the frontal lobes, and thus the most frequent cognitive sequelae are deficits in the prefrontal cortex (PFC)-dependent functions, such as attention, working memory, social behavior, mental flexibility, and task switching. Objective: The goal of this case report is to highlight the assessment and intervention of the dysphagia program. Case Report: The patient was diagnosed with diffuse axonal injury with bilateral frontal lobe contusion. The patient is receiving care in the Physical Medicine and Rehabilitation (PMR) unit, where they are undergoing physiotherapy occupational therapy, and speech therapy. Results: Speech Assessment revealed deviated voice and resonance characteristics with Substitution & Distortion of speech sounds. Swallowing assessment revealed Oro-pharyngeal Dysphagia. The patient was also undergoing Chemotherapy and Radiation-therapy. Recommendations for further follow-ups for speech & swallowing therapy and other medical management were made. Conclusion: This study is useful in creating evidence regarding the assessment & rehabilitation of Speech and swallowing in patients undergoing hemi-glossectomy. It also emphasizes the input from other medical professionals as an interdisciplinary team member.

Modeling and design of a SMA self-actuating bistable beam

Bistable beams with implanted actuators show the self-actuating ability that further improve performance of the system. In this paper, a novel self-actuating bistable mechanism coupled by elastic straight beam and SMA curved beam was designed and tested. Snap-back behavior of the presented system was triggered by SMA curved beam actuator, which generated actuation moment and rotation angle at the end of flexible beam. The bistable mechanism was modeled through nonlinear governing equation of large deflection beam. A solution strategy that considered multiple inflection points was developed to solve the governing equation. Loading path, deflection curves, and energy landscape of bistable beam were illustrated and further analyzed. Moreover, parameters of SMA curved beam actuator were determined by a simplified model. A prototype of the self-actuating bistable beam was fabricated and the snap-back phenomenon was observed on the test bench. Accompanied by the snap-back, a 44% decrease of axial load could be reached. It was also found that the bistable beam could be reset by applying vertical concentrated force. Reciprocating snap-back tests were conducted to confirm that point. Possible applications of the presented bistable beam could be variable load mechanisms and novel flexible switches.

Fixed-time adaptive event-triggered control for multiagent systems with full-state constraints

This paper investigates the fixed-time adaptive event-triggered control problem for a class of nonlinear multiagent systems with full-state constraints. The problem of full-state constraints is solved for multiagent systems by utilising a one-to-one nonlinear mapping. The design conditions of the controllers are more easily satisfied than the existing barrier Lyapunov functions strategy. A fixed-time adaptive control scheme is proposed for unconstrained systems that are converted from constrained systems. In contract with the existing finite-time control schemes that rely on the initial states, this restriction condition can be removed in this paper. An improved event-triggered mechanism with an adaptable switching threshold is designed to provide flexible switching between fixed threshold and variable threshold policies, resulting in reduced execution and sampling. It is proved via the Lyapunov stability method that all signals of the closed-loop systems are semi-global practical fixed-time stable. Finally, the effectiveness of the proposed control strategy is verified by some simulation results.

Exploiting Carbon Quantum Dots Synthesized by Electrochemical Exfoliation for Flexible Resistance Switching

Exploiting Carbon Quantum Dots Synthesized by Electrochemical Exfoliation for Flexible Resistance Switching

Actively Tunable "Single Peak/Broadband" Absorbent, Highly Sensitive Terahertz Smart Device Based on VO2.

In recent years, the development of terahertz (THz) technology has attracted significant attention. Various tunable devices for THz waves (0.1 THz-10 THz) have been proposed, including devices that modulate the amplitude, polarization, phase, and absorption. Traditional metal materials are often faced with the problem of non-adjustment, so the designed terahertz devices play a single role and do not have multiple uses, which greatly limits their development. As an excellent phase change material, VO2's properties can be transformed by external temperature stimulation, which provides new inspiration for the development of terahertz devices. To address these issues, this study innovatively combines metamaterials with phase change materials, leveraging their design flexibility and temperature-induced phase transition characteristics. We have designed a THz intelligent absorber that not only enables flexible switching between multiple functionalities but also achieves precise performance tuning through temperature stimulation. Furthermore, we have taken into consideration factors such as the polarization mode, environmental temperature, structural parameters, and incident angle, ensuring the device's process tolerance and environmental adaptability. Additionally, by exploiting the principle of localized surface plasmon resonance (LSPR) accompanied by local field enhancement, we have monitored and analyzed the resonant process through electric field characterization. In summary, the innovative approach and superior performance of this structure provide broader insights and methods for THz device design, contributing to its theoretical research value. Moreover, the proposed absorber holds potential for practical applications in electromagnetic invisibility, shielding, modulation, and detection scenarios.

Flexible switch matrix addressable electrode arrays with organic electrochemical transistor and pn diode technology

Due to their effective ionic-to-electronic signal conversion and mechanical flexibility, organic neural implants hold considerable promise for biocompatible neural interfaces. Current approaches are, however, primarily limited to passive electrodes due to a lack of circuit components to realize complex active circuits at the front-end. Here, we introduce a p-n organic electrochemical diode using complementary p- and n-type conducting polymer films embedded in a 15-μm -diameter vertical stack. Leveraging the efficient motion of encapsulated cations inside this polymer stack and the opposite doping mechanisms of the constituent polymers, we demonstrate high current rectification ratios (105\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${10}^{5}$$\\end{document}) and fast switching speeds (230 μs). We integrate p-n organic electrochemical diodes with organic electrochemical transistors in the front-end pixel of a recording array. This configuration facilitates the access of organic electrochemical transistor output currents within a large network operating in the same electrolyte, while minimizing crosstalk from neighboring elements due to minimized reverse-biased leakage. Furthermore, we use these devices to fabricate time-division-multiplexed amplifier arrays. Lastly, we show that, when fabricated in a shank format, this technology enables the multiplexing of amplified local field potentials directly in the active recording pixel (26-μm diameter) in a minimally invasive form factor with shank cross-sectional dimensions of only 50×8 μm2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\mu m}^{2}$$\\end{document}.

Two-stage optimization of hydrogen and storage coordination for a multi-region flexible intermodal multi-energy port system

To address the issue of imbalanced electricity and hydrogen supply and demand in the flexible multi-energy port area system, a multi-regional operational optimization and energy storage capacity allocation strategy considering the working status of flexible multi-status switches is proposed. Firstly, based on the characteristics of the port area system, models for system operating costs, generation equipment, energy storage devices, flexible multi-status switches, and others are established. Secondly, the system is subjected to a first-stage optimization, where different regions are optimized individually. The working periods of flexible multi-status switches are determined based on the results of this first-stage optimization, targeting the minimization of the overall daily operating costs while ensuring 100% integration of renewable energy in periods with electricity supply-demand imbalances. Subsequently, additional constraints are imposed based on the results of the first-stage optimization to optimize the entire system, obtaining power allocation during system operation as well as power and capacity requirements for energy storage devices and flexible multi-status switches. Finally, the proposed approach is validated through simulation examples, demonstrating its advantages in terms of economic efficiency, reduced power and capacity requirements for energy storage devices, and carbon reduction.

Programmable inverse-designed acoustic coding metasurfaces for multifunctional broadband reflection

In this paper, we develop tunable reflection-type broadband acoustic coding metasurfaces (BACMs) using a bottom-up topology optimization method. These metasurfaces enable flexible configuration switching between the antiphase coding units of “0” and “1” across a wide frequency range through electromagnetic regulation. By introducing a customized dispersion design, the optimized structure exhibits broadband properties. The optimized coding units consist of irregular air channels and connected air cavities. The coding bits of “0” and “1” show a constant opposite phase difference over a wide frequency range through the coupling resonances. By adjusting the electromagnets, arbitrary coding sequences in the BACMs can be rapidly reconstructed. We numerically and experimentally demonstrate the acoustic focusing and splitting properties within the frequency range of 2.2 kHz–4.4 kHz.