Average Switching Time Research Articles

Characterizing polarization switching kinetics of ferroelectric Hf0.5Zr0.5O2 at cryogenic temperature

We have characterized polarization switching kinetics of Hf0.5Zr0.5O2 (HZO) at cryogenic temperature (T) down to 100 K. By the nucleation-limited-switching model with Lorentzian distribution fittings, the dependences of the average switching time (log τ1) and switching time distribution (ω) on T are extracted. As T decreases from 300 to 100 K, log τ1 first rapidly decreases and then gradually stabilizes. Meanwhile, ω exhibits different trends under different external electric fields (Eext), decreasing under low Eext while increasing under high Eext, eventually stabilizing at non-zero constants. With the further decrease in T (<100 K), log τ1 and ω exhibited by HZO are almost unchanged, indicating the intrinsic properties of ferroelectric multiple domains, which are different from the prediction in previous literature studies that log τ1 and ω will linearly decrease as T decreases.

Lévy noise-induced effects in a long Josephson junction in the presence of two different spatial noise distributions

We analyze the impact of Lévy-distributed stochastic fluctuations on the average switching time and voltage drop across a current-biased long Josephson tunnel junction. We compare the system’s response for two spatial configurations of time-dependent noise, i.e., homogeneous and distributed along the junction length. The response of the Josephson junction is explored by varying the characteristic parameter of the Lévy source, i.e., the α stability index and the noise intensity. These findings offer an effective tool to characterize a Lévy component possibly embedded in an unknown noise signal.

Encouraging thermostatically controlled loads to provide frequency regulation for smart grid: A comfort-level trading mechanism

This paper presents a comfort-level trading mechanism for thermostatically controlled loads (TCLs), aiming to incentivize customers to provide more frequency regulation service for smart grid. This mechanism firstly divides aggregators composed of TCLs into the leader layer and the follower layer according to comfort adjustment level produced by the fuzzy neural network controller (FNC). The aggregator at leader layer has a low regulation level, while aggregators at follower layer are high. Then we establish a Stackelberg game between leader layer and follower layer, which can optimize the customer utility. Meanwhile, we build a noncooperative game model among aggregators at follower layer, which can maximize the customer utility while supplying regulation capacity for leader layer. Finally, simulation results validate the effectiveness of FNC and the feasibility of trading mechanism. The FNC can improve tracking accuracy to 2.05%, reduce absolute tracking error to 208.4 kW, and decrease average switching times to 9 per hour. The trading mechanism can make the temperature setpoints of aggregators within their comfort range and improve the customer satisfaction.

Bio-inspired multi-hop clustering algorithm for FANET

Clustering has received extensive attention in recent years as an important approach to address the poor scalability in flying ad hoc networks (FANETs). However, due to the highly mobile nature of FANETs, frequent changes in cluster topology result in increased control overhead and reduced communication efficiency. To tackle these challenges, a novel heuristic clustering algorithm called the physarum-inspired clustering algorithm (PICA) is proposed in this paper. It leverages the intelligence and adaptability of Physarum polycephalum. The PICA adopts a distributed multi-hop clustering approach. During the cluster formation phase, and inspired by the foraging behavior of Physarum polycephalum, the algorithm incorporates link stability, residual energy, and link communication quality as evaluation metrics, thereby ensuring cluster coverage and stability. By selecting the most stable node within an n-hop range as the cluster head, the cluster stability is significantly enhanced. In the cluster maintenance phase, the PICA improves the backup cluster head selection mechanism and introduces damage detection and cluster merging mechanisms to further enhance the robustness and stability of clusters. Experimental results demonstrate that compared to existing EMASS and OSCA algorithms, the proposed PICA reduces the average end-to-end delay by 31.6 % and 25.27 %, improves the average packet delivery ratio by 27.7 % and 19.12 %, and decreases the average inter-cluster switching times by 14.71 % and 14.38 %, respectively. In conclusion, the PICA effectively addresses the issue of poor scalability in FANETs by leveraging the intelligence of multi-headed myxobacteria and adopting a multi-hop clustering approach. As indicated by experimental results, the proposed algorithm demonstrates significant performance improvements in terms of network metrics.

Bistability in the wake of a circular cylinder with passive control using two leeward rods

This paper presents an experimental investigation on the flow around a circular cylinder controlled by a pair of rods placed close to the separated shear layers from the leeward face of the cylinder. Past research of Cicolin et al. (2021) has shown that one control rod, placed at specific positions, induces a late flow separation on the main cylinder’s surface in a typical occurrence of the Coandă effect. As a result the control rod reduced the mean drag acting on the cylinder but also produced a net mean lift force. We now present an extension of the aforementioned study to consideration of a pair of symmetrically arranged control rods, aimed at eliminating the mean lift force whilst maintaining a drag reduction. The experiments were carried out at a Reynolds number Re=20,000 based on the diameter of the main cylinder D, with the diameter of the control rods being ten times smaller than that of the cylinder. The centre-to-centre distances between each control rod and the cylinder was 0.7D, and the angular position of the rods varied from θ=120∘ to 125∘, where θ is measured from the front stagnation point. Time-resolved PIV velocity fields and hydrodynamic forces were measured for the different setups. Results show that the mean flow is asymmetric in spite of the symmetry of the geometric model and position of the rods. The pair of control rods induces a bistable flow, induced by the imbalance of two colliding jets in the near wake. The dynamics were found to be random, with the average switching time between stable states depending on the position of the rods. The mean drag force was reduced by up to 15%, and the mean lift force was reduced by 80% compared to the cases with a single control rod. It was also observed that the control rod can induce two different types of flow separation from the main cylinder, one in which the flow separates from the main cylinder only once and one in which a small separation bubble forms in proximity to the control rod before reattaching and then permanently separating. These distinct features play an important role in the dynamics of the bistability and hint at a possible extension of the total drag reduction to 30% if the bistability is suppressed.

Triple-layered optical interconnecting integrated waveguide chip based on epoxy cross-linking fluorinated polymer photonic platform.

In this study, a triple-layered optical interconnecting integrated waveguide chip was designed and fabricated using an epoxy cross-linking polymer photonic platform. Fluorinated photopolymers FSU-8 and AF-Z-PC EP were self-synthesized as waveguide cores and cladding materials, respectively. The triple-layered optical interconnecting waveguide device comprised 4 × 4 arrayed waveguide grating (AWG) -based wavelength-selective switching (WSS) arrays, 4 × 4 multi-mode interference (MMI) -cascaded channel-selective switching (CSS) arrays, and 3 × 3 direct-coupling (DC) interlayered switching arrays. The overall optical polymer waveguide module was fabricated by direct UV writing. For the multilayered WSS arrays, the wavelength-shifting sensitivity was ∼0.48 nm/°C. For the multilayered CSS arrays, the average switching time was ∼280 µs, and the maximum power consumption was <30 mW. For interlayered switching arrays, the extinction ratio approximated 15.2 dB. The transmission loss for the triple-layered optical waveguide chip was measured as 10.0-12.1 dB. The flexible multilayered photonic integrated circuits (PIC) can be used in high-density integrated optical interconnecting systems with a large-volume optical information transmission capacity.

I-GSI: A Novel Grasp Switching Interface Based on Eye-Tracking and Augmented Reality for Multi-Grasp Prosthetic Hands

Controlling multi-grasp prosthetic hands remains challenging due to the lack of an intuitive and efficient interface for enabling a suitable grasping pattern. To solve this problem, we propose an eye-tracking based grasp switching interface (i-GSI) that integrates the “GazeButton” from augmented reality (AR) to elicit the intended grasp patterns from eye movements. The i-GSI is fully implemented in HoloLens 2 (Microsoft, USA), and its user can easily switch between six grasp types with just a glance at the GazeButtons. Experiments on eight healthy subjects shows that the average switching time is nearly 0.84 s, with a success rate of 99.0% and a learning efficiency of 93.5%. Results on a congenital amputee also shows a similar outcome (switching time 0.78 s, success rate 100%). Compared with the other three traditional methods, our i-GSI achieved the best performance. The i-GSI also shows a superior adaptability to different users with various amputation levels, when combining with a simple myoelectric control (such as, two-sites proportional control).

Optical switching of bent-core liquid crystals with azocinnamoyl units

ABSTRACTWe report on observations of optical switching in bent-core liquid crystals possessing azocinnamoyl groups in both elongated side arms. UV-activated switching was observed in two of the synthesised materials, both of which were studied optically and with dielectric spectroscopy. Polarising microscopy was used to measure the changes in optical transmittance, and while no illumination effect was seen in the nematic phase, visible changes were observed in the smectic phase, most pronounced in the close vicinity of the smectic to nematic-phase transition. Switching dynamics was characterised, and we found that the average switching time varies strongly with temperature. The relaxation process is faster (below 200ms) and exhibits no significant temperature dependence. Dielectric measurements have shown that the observed smectic C phases were not polar with the molecules possessing a rather small electric dipole moment. Upon illumination, small differences in the dielectric permittivity were observed only in the smectic phase, suggesting that the illumination effect can be attributed to changes in the molecular conformational and orientational order.

Field Programmable Gate Array Based Torque Predictive Control for Permanent Magnet Servo Motors.

With the increasing demand for legged robots, the importance of the joint drive is increasing. The dynamic performance of the inner-most torque/current control loop conditions the capabilities of the whole joint system. In this paper, a direct torque control based on a prediction model is proposed. The motor torque is estimated by considering calculation and measurement delay; error estimation and torque tracking error are observed and compensated. The control algorithm was implemented on a Field Programmable Gate Array (FPGA) board to apply the capabilities of concurrency calculation of the FPGA. The effectiveness of the proposed control algorithm was experimentally verified. Compared with the commonly used Field Oriented Control (FOC) current controller, the presented controller can not only improve the dynamic performance of the motor but also reduce the average switching times of the inverter.

Polysilicon micro-heaters for resonance tuning in CMOS photonics.

A new, to the best of our knowledge, device platform for tuning the resonance wavelength of integrated photonic resonators based on polysilicon-based micro-heaters for complementary metal-oxide semiconductor (CMOS)-foundry-based active Si photonics is demonstrated. The miniaturized micro-heater can be placed directly on the active Si layer, with a pedestal providing the optical and electrical isolation needed for the implementation of ultrafast active photonic devices such as modulators. The demonstrated devices do not require any additional modifications to the standard CMOS foundry processes. Experiments demonstrate a tuning efficiency of 0.25 nm/mW (or 42 GHz/mW) for a 5-µm-radius microdisk resonator with a loaded quality factor (Q) > 35,000. This polysilicon-based heater demonstrates a tunability of 42 GHz/mW with an average switching time of 60 µs. The proposed compact heater architecture enables it to be kept near to the optical mode, thereby providing efficient and high-speed wavelength tuning for resonant devices.

Supporting Targeted Advertising in Integrated Broadcast-Broadband Systems With Automatic Media Content Preparation

Integrated Broadcast-Broadband (IBB) Systems enable a range of new services for viewers, including content personalization, such as targeted advertising. Custom advertising is delivered using the broadband connection synchronized with the broadcast content, demanding high-control synchronization among both communication channels. As the broadband channel is shared among different applications, delays may occur during the transmission of targeted advertisements, which can cause synchronization faults. Aiming at reducing these faults and truly supporting targeted advertising in IBB systems, this work proposes the automatic preparation of media content before its presentation. In order to provide automatic preparation, a preparation plan to orchestrate content loading in advance is also proposed. Our proposal is implemented in the Ginga-NCL middleware, which is a standard for the Brazilian Digital TV System. Our performance evaluation shows that the average switching time from broadcast to broadband is around 40 ms, if automatic content preparation is used, which is an outstanding result.

Inkjet Printed Circuits with 2D Semiconductor Inks for High‐Performance Electronics

AbstractAir‐stable semiconducting inks suitable for complementary logic are key to create low‐power printed integrated circuits (ICs). High‐performance printable electronic inks with 2D materials have the potential to enable the next generation of high performance low‐cost printed digital electronics. Here, the authors demonstrate air‐stable, low voltage (&lt;5 V) operation of inkjet‐printed n‐type molybdenum disulfide (MoS2), and p‐type indacenodithiophene‐co‐benzothiadiazole (IDT‐BT) field‐effect transistors (FETs), estimating an average switching time of τMoS2 ≈ 4.1 μs for the MoS2 FETs. They achieve this by engineering high‐quality MoS2 and air‐stable IDT‐BT inks suitable for inkjet‐printing complementary pairs of n‐type MoS2 and p‐type IDT‐BT FETs. They then integrate MoS2 and IDT‐BT FETs to realize inkjet‐printed complementary logic inverters with a voltage gain |Av| ≈ 4 when in resistive load configuration and |Av| ≈ 1.4 in complementary configuration. These results represent a key enabling step towards ubiquitous long‐term stable, low‐cost printed digital ICs.

Fabrication and assessment of an electrochromic and radar-absorbent dual device based on the new smart polythiophene-based/RGO/Fe3O4 ternary nanocomposite

Both polymeric electrochromic and radar absorption materials have been considered as science hotspots over the past few decades. However, integrating both properties (electrochromic and radar absorption) in a single device has not been addressed to fabricate a multifunctional device so far. Thus, here, we endeavor to shed light on this uncharted area by presenting a new smart ternary nanocomposite (polythiophene-based/RGO-Fe3O4) which can provide both electrochromic and microwave absorbent features simultaneously. In this regard, we synthesized the binary Fe3O4-RGO nanocomposites with different contents of Fe3O4 nanoparticles. Then, this binary nanocomposite is utilized in combination with a polythiophene-based conductive polymer as a tricolor (RGB) organic electrochromic material to synthesize the smart ternary nanocomposite through both in-situ polymerization and physical mixing methods. The ternary nanocomposites containing different weight fractions of Fe3O4-RGO nanoparticles were used to assemble the rigid and flexible ECD devices using flat and fiber substrates such as glass-indium tin oxide (glass-ITO), polyethylene terephthalate-indium tin oxide (PET-ITO) and stainless steel wire (SSW). By applying a voltage of −2.1 to 2.1 v, a reversible color-switching ability was observed between green color (oxidized state), and red color (reduced state) for all ECDs. The average switching time and color memory for the SSW cell were determined to be about 3 s and 155 min, and for both glass-ITO and PET-ITO cells to be 2 s and 210 min, respectively. Additionally, the microwave absorption properties of the prepared ternary nanocomposites were characterized by measuring the electromagnetic parameters such as permittivity, permeability, and reflection loss. A ternary nanocomposite with 3 mm thickness filled with 50 wt% Fe3O4-RGO exhibited a maximum reflection loss as high as −30.2 dB (92% absorption) at 12.3 GHz (in the range of x-bond) with 1.1 GHz bandwidth.

High-Performance Silicon 2 × 2 Thermo-Optic Switch for the 2-$\mu$m Wavelength Band

The 2- $\mu$ m spectral window is emerging as a promising candidate for the next generation communication. We present a 2 × 2 Mach–Zehnder interferometric thermo-optic switch at 2- $\mu$ m waveband. The device is fabricated on a 220 nm thick silicon-on-insulator wafer with standard complementary metal oxide semiconductor (CMOS) process. We demonstrate an over 30 dB extinction ratio under the power consumption of 32.3 mW, with an average switching time of ∼15 μs. This proof of principle optical switch paves a way toward full silicon-based chip-scale interconnects in the 2- $\mu$ m waveband.

Magnetization switching in nanoelements induced by the spin-transfer torque: Study by massively parallel micromagnetic simulations

In this paper we present a detailed numerical study of magnetization switching in shape-anisotropic thin-film nanoelements. These elements are at present of the major interest for the applied solid state magnetism as main components of a new generation of conventional and spin-transfer-torque (STT) magnetic random access memory (MRAM) cells. To conduct this study, we have developed a highly efficient method for massively parallel micromagnetic simulations of the magnetization reversal in small-size nanoelements, which allows to fully exploit the large performance gain available on the GPU architecture (usually achievable only for large systems). We apply our method to the spin-torque-induced magnetization switching in elliptical nanoelements in presence of thermal fluctuations. Being able to compute simultaneously the reversal of up to 1000 such elements, we obtain the dependence of (i) the average switching time and (ii) the distribution density of switching times for individual elements on the element size with a high statistical accuracy. Analysis of these dependencies provides important insights into the physics of magnetization reversal in such systems. Comparison with analogous simulations in the macrospin approximation allows to determine the validity limits of the macrospin model. Our methodology can be applied for the optimization of the MRAM design regarding the information life time and significantly improve the prediction accuracy of write and read error rates of conventional and STT-based MRAM cells.

A 1 MV AMS system for analysis of actinides

HVE has designed a new high-energy side mass spectrometer with two detection beamlines for its 1 MV multi-element AMS system, supporting analysis of rare isotopes ranging from 10Be to 244Pu. The beam line that is used for actinide measurements features two high-resolution analyzing magnets with a spherical electrostatic analyzer (ESA) in between and is designed for minimizing measurement background from interfering masses. The mass-energy product of the analyzing magnets of nominal 100 (max 108) AMU × MeV supports measurement of 129I2+ or 244Pu3+ from PuO− at 1 MV terminal voltage. The radius of the magnets was chosen to be 1.2 m to keep its nominal field at a relatively low 1.2 T, avoiding degradation of ion optical quality by saturation effects.For the analysis of actinides like Pu, typically up to 5 isotopes are measured in a cyclic fashion. For this, both high-energy side analyzing magnets are equipped with bouncing capability to direct the various isotopes into suitable Faraday cups or into the final gas ionization detector. Average switching times of the high-energy magnets during bouncing are below 10 ms, and 8 isotopes can be measured at a cycle frequency of more than 1 Hz. Because the various isotopes have a small, but noticeable energy difference in the high-energy spectrometer, a deflector with bouncing capability is incorporated in the mid-plane of the ESA. Minor adjustment of the deflector voltage is incorporated in the isotope cycling, thereby optimizing the transmission of every individual isotope.

Landscape reveals critical network structures for sharpening gene expression boundaries

BackgroundSpatial pattern formation is a critical issue in developmental biology. Gene expression boundary sharpening has been observed from both experiments and modeling simulations. However, the mechanism to determine the sharpness of the boundary is not fully elucidated.ResultsWe investigated the boundary sharpening resulted by three biological motifs, interacting with morphogens, and uncovered their probabilistic landscapes. The landscape view, along with calculated average switching time between attractors, provides a natural explanation for the boundary sharpening behavior relying on the noise induced gene state switchings. To possess boundary sharpening potential, a gene network needs to generate an asymmetric bistable state, i.e. one of the two stable states is less stable than the other. We found that the mutual repressed self-activation model displays more robust boundary sharpening ability against parameter perturbation, compared to the mutual repression or the self-activation model. This is supported by the results of switching time calculated from the landscape, which indicate that the mutual repressed self-activation model has shortest switching time, among three models. Additionally, introducing cross gradients of morphogens provides a more stable mechanism for the boundary sharpening of gene expression, due to a two-way switching mechanism.ConclusionsOur results reveal the underlying principle for the gene expression boundary sharpening, and pave the way for the mechanistic understanding of cell fate decisions in the pattern formation processes of development.

МАТЕМАТИЧЕСКАЯ МОДЕЛЬ КОММУТАЦИИ В СРЕДСТВАХ С ПОЛНОСВЯЗНУЮ ТОПОЛОГИИ В СЕТЯХ АСУВОЗДУШНЫМ ДВИЖЕНИЕМ

Предложена модель коммутации, которая позволяет оценить пропускную способность узлов распределенной сети автоматизированной системы управления воздушным движением. Предложены пути повышения эффективности функционирования средств коммутации. В результате моделирования получены зависимости среднего времени коммутации от вероятности мультиплексирования пакетов при различных коэффициентах и вероятности буферизации.

Correlated noise-based switches and stochastic resonance in a bistable genetic regulation system

The correlated noise-based switches and stochastic resonance are investigated in a bistable single gene switching system driven by an additive noise (environmental fluctuations), a multiplicative noise (fluctuations of the degradation rate). The correlation between the two noise sources originates from on the lysis-lysogeny pathway system of the λ phage. The steady state probability distribution is obtained by solving the time-independent Fokker-Planck equation, and the effects of noises are analyzed. The effects of noises on the switching time between the two stable states (mean first passage time) is investigated by the numerical simulation. The stochastic resonance phenomenon is analyzed by the power amplification factor. The results show that the multiplicative noise can induce the switching from “on” → “off” of the protein production, while the additive noise and the correlation between the noise sources can induce the inverse switching “off” → “on”. A nonmonotonic behaviour of the average switching time versus the multiplicative noise intensity, for different cross-correlation and additive noise intensities, is observed in the genetic system. There exist optimal values of the additive noise, multiplicative noise and cross-correlation intensities for which the weak signal can be optimal amplified.

The role of stochastic gene switching in determining the pharmacodynamics of certain drugs: basic mechanisms.

In this paper we analyze the impact of the stochastic fluctuation of genes between their ON and OFF states on the pharmacodynamics of a potentially large class of drugs. We focus on basic mechanisms underlying the onset of in vitro experimental dose-response curves, by investigating two elementary molecular circuits. Both circuits consist in the transcription of a gene and in the successive translation into the corresponding protein. Whereas in the first the activation/deactivation rates of the single gene copy are constant, in the second the protein, now a transcription factor, amplifies the deactivation rate, so introducing a negative feedback. The drug is assumed to enhance the elimination of the protein, and in both cases the success of therapy is assured by keeping the level of the given protein under a threshold for a fixed time. Our numerical simulations suggests that the gene switching plays a primary role in determining the sigmoidal shape of dose-response curves. Moreover, the simulations show interesting phenomena related to the magnitude of the average gene switching time and to the drug concentration. In particular, for slow gene switching a significant fraction of cells can respond also in the absence of drug or with drug concentrations insufficient for the response in a deterministic setting. For higher drug concentrations, the non-responding fraction exhibits a maximum at intermediate values of the gene switching rates. For fast gene switching, instead, the stochastic prediction follows the prediction of the deterministic approximation, with all the cells responding or non-responding according to the drug dose.