Overshoot Effect Research Articles

Can BDNF manipulate the overshoot-and-decline effect of adult neurogenesis during recovery from sleep deprivation?

Sleep deprivation reduces an organisms ability to perform adult neurogenesis, the generation of new neurons in adulthood. Recently, researchers discovered that recovery in sleep deprivation causes the rate of adult neurogenesis to overshoot the normal rate, and then decline back to normal. This research focuses on brain-derived neurotrophic factor, and whether or not manipulating it and its related pathways could extend the overshoot effect to enhance adult neurogenesis in the long term. The conclusion that is expected from this research is that BDNF will be able to prolong the overshoot of adult neurogenesis that is induced by sleep deprivation. The work seeks to provide more control over the overshoot-and-decline effect of adult neurogenesis during recovery from sleep deprivation, opening new pathways to treatments involving the manipulation of adult neurogenesis.

A cold-electrode metal–oxide resistive random access memory

To reduce the leakage and power consumption of metal–oxide resistive random access memory (RRAM), we propose and fabricate a cold-electrode (CE) RRAM (CE-RRAM) by extending the mechanism of cold-source FETs. First-principles calculations show that the n-Si/TiN composite CE can filter electrons with energy within the Si bandgap, which contribute to leakage current. A n-Si/TiN/HfOx/Pt CE-RRAM with low leakage current and large on/off current ratio was designed and fabricated. Comparative analysis with conventional RRAM demonstrates over a 100-fold reduction in leakage current in a high resistance state and a tenfold improvement in the Ion/Ioff ratio. Additionally, the CE-RRAM effectively suppresses the overshoot effect in terminal I–V characteristics and exhibits good endurance, maintaining a 100 Ion/Ioff ratio after 104 cycles. Furthermore, even after 104 s at 100 °C, the state remains unchanged. Moreover, the CE-RRAM demonstrates its multi-level storage capability.

Deciphering the Dynamic Assembling-Disassembling of Small Molecules on Solid/Liquid Interfaces within Microchannels by Pulsed Streaming Potential Measurement.

Assembling small molecules at liquid/solid interfaces is relatively common and contributes to many unique properties of the interface. However, such an assembling process can be dynamic depending on the concentration of the molecule and the properties of the solid and liquid themselves, which poses serious challenges on the accurate evaluation of the assembling processes. Herein, we report a convenient way for in situ and real-time monitoring of assembling-disassembling of small-molecule surfactants on the surface of microchannels using pulsed streaming potential (SP) measurement based on the variation of surface charge. With this technique, five distinctive kinetic regimes, each responsible for a characteristic molecular behavior, can be differentiated during a typical assembling-disassembling cycle. Significant difference of the assembling-disassembling process was clearly reflected for surfactants with hydrophobic tails of only a two -CH2- difference (C16TAB/C18TAB and D10DAB/D12DAB). The relative SP (Er) value is positively correlated with the molecular weight at a concentration of 0.1 mM for the same kinds of surfactants. Moreover, the assembling kinetics of D10DAB exhibits an "overshoot effect" at high concentration, which means morphology adjustment. The consequences of such assembling/disassembling of these molecules for electrophoretic separation, protein immobilization, and photocatalysis in a microchannel were investigated through dynamic characterization, which proves its potential as a tool for dynamic solid/liquid interface characterization.

Electronic transport properties of WS2 using ensemble Monte Carlo method

The electronic transport characteristics of tungsten disulfide (WS2) sheets are studied using the ensemble Monte Carlo technique in the presence of intrinsic scattering mechanisms only. The transport properties of the material are obtained in a two-valley model where intra- and inter-valley scatterings are considered in K and Q valleys. The velocity overshoot effect is observed for some applied field values. Negative differential phenomena are seen for some values of the energy difference between K and Q valleys ( ΔEKQ ), therefore ΔEKQ and the effective mass of carriers in the Q valley has a critical role in the transport and mobility characteristics of WS2. The mobility of carriers is calculated as a function of temperature and the results are compatible with some existing theoretical and experimental predictions.

Ballistic performance and overshoot effects in gallenene nanoribbon field-effect transistors

Gallenene is a novel metallic 2D material that can provide a semiconducting counterpart if patterned into quasi-one-dimensional (quasi-1D) nanostructures, i.e., gallenene nanoribbons (GaNRs). We investigate semiconducting GaNRs as a potential channel material for future ultrascaled field-effect transistors (FETs) by employing quantum transport simulations based on Green's functions and tight-binding Hamiltonians with the orbital resolution calibrated on ab initio calculations. The impact of GaNR width downscaling from ∼6 nm down to ∼0.2 nm on the electronic, transport, and ballistic device properties is investigated for the FET channel length of 15 nm. We report current enhancement and injection velocity overshoot effects for sub-1.2 nm-wide nFETs and pFETs, with a maximum current increase of 53% in the 1.2 nm-wide GaNR pFET in comparison to the widest device. In addition, promising current-driving capabilities of n- and p-channel GaNR FETs are observed with top ballistic currents of more than 2.2 mA/μm and injection velocities of up to 2.4 × 107 cm/s. The reported data are explained by analyzing the evolution of band structure and related parameters such as injection velocity, quantum capacitance, effective transport mass etc., with increasing quantum confinement effects in ultranarrow GaNRs. Generally, we find that quasi-1D gallenene is a promising channel material for future nanoscale FETs, especially for transistor architectures based on stacked nanosheets.

Control of time-delay systems through modified Smith predictor using sliding mode controller

Smith-Predictor (SP) is used as a dead-time compensating tool for chemical processes as they are Integrating-Plus-Dead-Time (IPDT), pure integrating-type process, and higher-order-integrating-process. The performances of these processes can be improved by modifying SP. The present work deals with the control of dead-time by integrating the first-order-plus-dead-time (IFOPDT) or first-order-plus-dead-time process (FOPDT), and a modified sliding-mode-controller (SMC) in the proposed modified-Smith-predictor (MSP) structure. Here, a modified novel SMC discontinuous tuning-parameter is derived analytically to satisfy performance criteria such as speed adjustment, reducing overshoot and chattering effects. Furthermore, the MSP-SMC structure is implemented in six different processes. This is done to counteract time-delay and constant load-disturbance for integrating processes and a nonlinear system separately. Also, the proposed work is implemented in the real-time lab setup of a neutralisation process. Furthermore, the robustness and invariance properties of the SMC have been analysed against parametric uncertainty. The optimality of the proposed controller parameters is tested by giving uncertainty in the dead time of the process parameters. The proposed design is also implemented in the non-linear and Multi-Input-Multi-Output processes. The performance metrics, IAEs, of 6 case studies have been obtained using MATLAB and the peak overshoots are compared with similar kinds of works.

The response of geographical processes to landscape restoration: China’s research progress

The UN Decade of Ecosystem Restoration (2021–2030) provides a new momentum for scaling up ecosystem restoration efforts to landscape restoration. China’s recent experience with transformative investment in landscape restoration provides invaluable guidance for the world. We retrospectively reviewed the scientific evidence on the responses of physical, ecological, and social processes to China’s landscape restoration under geographic heterogeneity and obtained four experiences and lessons. First, China’s forest landscape restoration has successfully promoted vegetation growth and enlarged the carbon sink. Second, landscape restoration has reduced the local water yield, while the regional responses of rainfall are still not clear. Third, the local conditions of soil erosion and habitat quality were largely improved by landscape restoration, while the decreases in soil moisture and streamflow demonstrated significant trade-offs among ecosystem services. Last, geographical differentiation existed in the local responses of livelihoods to landscape restoration strategies, and the win‒win solutions between human development and nature improvement under different landscape contexts were still uncertain. We summarize three additional questions as future prospects: what is the scale of the thresholds to prevent overshoot and cascading negative ecological effects? what are people’s prior needs from nature? considering that there may be no universal win‒win pathways, how to promote co-benefits based on regional human–nature relationships?

Double-ended output near-single-mode quasi-continuous wave monolithic fiber laser

Quasi-continuous fiber lasers have a broad application prospect in the industrial field. However, in the current research on quasi-continuous wave (QCW) fiber lasers only the single-ended output structure is used. A double-ended output fiber laser oscillator needs only one resonator to realize two laser outputs. Compared with single-ended output laser, it has a low cost, small volume and high work efficiency. It is expected to achieve higher power laser output through double-ended output beam combining. Therefore, the double-ended output QCW fiber laser is proposed and studied in this paper. The steady-state rate equation establishes a theoretical model of a QCW fiber laser oscillator with two ends, considering the stimulated Raman scattering (SRS) and amplified spontaneous emission (ASE). The output power, time domain and nonlinear effects of this type of laser are simulated. The results show that the overshoot effect caused by relaxation oscillation will produce a large amount of thermal deposition and ultra-high peak power in the fiber. It will reduce the nonlinear threshold and limit the increase of power of the QCW fiber laser. Prolonging the rise time of the pump can effectively suppress the relaxation oscillation and obtain a stable pulse output during the pulse duration. In addition, compared with the single-ended QCW laser, the double-ended output structure changes the energy distribution in the fiber and reduces the accumulation of nonlinear effects in the gain fiber, thus inhibiting SRS. Then, the ytterbium-doped fiber with a core/cladding diameter of 20/400 μm is used to achieve the first double-ended QCW laser output with a peak power of 3 kW. The peak power values at both ends are 1218 and 2220 W, respectively. The values of corresponding beam quality factor <i>M</i><sup>2</sup> are 1.34 and 1.27. The optical-to-optical conversion efficiency is about 60%. The pulse width is 100 μs, and the repetition frequency is 1 kHz. This research verifies the feasibility of high power and high beam quality output by double-ended output QCW fiber laser, which provides support for small volume, low cost, high power and high brightness QCW fiber laser. Further breakthroughs in the research and application of high-power fiber lasers are expected to be made by continually optimizing experiments, increasing pump power, and improving the laser’s output power and conversion efficiency.

Local overshoot and wind effects on wave overtopping at vertical coastal structures

Wind effects on wave overtopping over a fully impermeable vertical sea wall were studied numerically using the open-source computational fluid dynamics library OpenFoam. A pressure gradient correction term was incorporated in the momentum equations. In recent studies, it was found that, in the absence of wind, an increase in wave steepness results in a reduction of wave overtopping. This is related to the instability of the standing wave formed at the front of a vertical structure. Such instability was noticed in the range of steepness 0.285–0.443 from previous physical experiments for a regular wave interacting with a vertical structure. The existence of this regime was confirmed in the current study. It was also found that the stability of the standing wave determines the shape and volume of the overshooting jet, which has a strong effect on wave overtopping. When the wind is relatively weak (e.g. a wind speed of 10 m/s) it is unable to alter the overshooting jet very much, meaning a weak wind effect on wave overtopping. When the wind is strong (e.g. a wind speed of 30 m/s) it completely deforms the overshooting jet resulting in overtopping discharge almost three times that without wind.

Dynamic Steady State in Coastal Aquifers Is Driven by Multi‐Scale Cyclical Processes, Controlled by Aquifer Storativity

AbstractCoastal aquifers supply freshwater to nearly half the global population, yet they are threatened by salinization. Salinities are typically estimated assuming steady‐state, neglecting the effect of cyclical forcings on average salinity distributions. Here, numerical modeling is used to test this assumption. Multi‐scale fluctuations in sea level (SL) are simulated, from tides to glacial cycles. Results show that high‐frequency fluctuations alter average salinities compared with the steady‐state distribution produced by average SL. Low‐frequency forcing generates discrepancies between present‐day salinities estimated with and without considering the cyclical forcing due to overshoot effects. This implies that salinities in coastal aquifers may be erroneously estimated when assuming steady‐state conditions, since present distributions are likely part of a dynamic steady state that includes forcing on multiple timescales. Further, typically neglected aquifer storage characteristics can strongly control average salinity distributions. This has important implications for managing vulnerable coastal groundwater resources and for calibration of hydrogeological models.

Improved PD of LESO quadrotor control algorithm

Abstract Aiming at the attitude instability problem caused by the quadrotor’s nonlinearity, strong coupling and susceptibility to external interference, a linear extended state observer (LESO) controller with improved PD was designed. First, the incomplete differential control is formed by adding a first-order inertia system to the differential Elements of the PD algorithm. Then, LESO is used to estimate and compensate the internal and external disturbances in the control system to the original system, which can not only reduce system errors, but also enhance the anti-interference ability of the control system. The MATLAB simulation shows that the improved PD of LESO controller can quickly reach a stable state, effectively improve the stable control ability of the quadrotor’s attitude, with smaller overshoot and better control effect.

Construction Method of Enterprise-level Database Operational Measurement Platform Based on Bidirectional Coupling Algorithm

When identifying the enterprise database data information, the enterprise database operational dimension measurement platform based on the bilinear method will produce ringing or overshoot effect, the database data monitoring effect is poor as well as the accuracy of operation measurement. To solve this problem, this paper proposes a method to build an enterprise level database operation and maintenance measurement platform based on bidirectional coupling algorithm. Build enterprise database operation measurement platform. The enterprise database monitoring platform is connected with the monitoring database by remote database chain. The Oracle database job scheduling method is used to obtain the monitoring index information in the monitored database, and the database memory performance is comprehensively evaluated by MPI (Memory Perform Index). The platform uses semantic capture layer and related analysis layer to distinguish user behavior, analyze user experience satisfaction, and realize the operation measurement of enterprise level database. The experimental results show that the operational measurement platform built by this method has high throughput, low memory occupancy rate, high measurement accuracy and good user experience.

Is pressure the key to hydrogen ordering ice IV?

Hydrochloric-acid-doped ice IV prepared at increasing pressures leads to growing endotherms observed with ambient pressure calorimetry. The endotherms are irreversible suggesting three possible scenarios for their origins: (1) a weakly hydrogen-ordered counterpart of ice IV is formed, but ambient pressure favours hydrogen-disordered ice IV, (2) increased pressure creates increased strain within the crystal structure of the ice, which is released upon heating yielding the endotherms or (3) the endotherms are kinetic overshoot effects related to the underlying orientational glass transition. X-ray diffraction cannot distinguish between these scenarios. Recent controversies regarding the preparation of ice IV are also discussed.

Dynamic analysis of current overshoots in reversible solid oxide cells

Reversible solid oxide cell (RSOC) has attracted significant attention due to its multi-functionalities for energy conversion and storage. This device works as a fuel cell (FC) or an electrolyzer cell (EC) with superior efficiency. However, its dynamic response is complex and may cause a large overshoot of current operated in reversible cell mode, which impairs the long-term stability of RSOC. Although several works report the overshoot phenomenon, the mechanism and effects on cell performance are still unclear so far. In this work, we build a 3D dynamic planar RSOC model to investigate the detailed behavior of overshoot. The results show that the overshoot of current for RSOC can be caused under switching mode conditions. Especially a larger overshoot of current can be observed within switching mode from EC to FC. The overshoot of current is mainly caused by the load change, slower gas diffusion, and differentiated temperature distribution in RSOC.

Enhancement of Disturbance Rejection Capability in Dual Three-Phase PMSM System by Using Virtual Impedance

Dual three-phase permanent magnet synchronous machine systems usually suffer from small impedance to voltage disturbance such as inverter voltage errors and back EMF harmonics. This article proposes a virtual impedance technique to increase the machine equivalent impedance and, thus, enhance the disturbance rejection capability of the system. This enhancement can contribute to current harmonic suppression in a wide range of frequencies. In addition, the introduction of virtual impedance can also reduce the system sensitivity to parameter variation, which helps to suppress the dynamic current overshoot, pulsating, and cross-coupling effect caused by the parameter mismatch. Simulation and experimental results have verified the effectiveness of the proposed control strategy.

Dynamics and nonmonotonic drag for individually driven skyrmions

We examine the motion of an individual skyrmion driven through an assembly of other skyrmions in the absence of quenched disorder. The skyrmion behavior is determined by the ratio of the damping and Magnus terms, known as the intrinsic skyrmion Hall angle. For fixed drive in the damping dominated regime, the effective viscosity decreases monotonically with increasing skyrmion density. In contrast, in the Magnus dominated regime, the velocity varies nonmonotonically with density, and there is a regime in which the skyrmion moves faster with increasing density, as well as a pronounced speed-up effect in which a skyrmion traveling through a dense medium moves more rapidly than for low densities or the single-particle limit. The velocity-force curves in the Magnus-dominated regime exhibit an overshoot effect and other differences from the damping-dominated regime. We find a finite threshold force for skyrmion motion which increases with density as well as a drive-dependent skyrmion Hall angle. We map dynamic phase diagrams showing the threshold for motion, nonlinear flow, speed-up, and saturation regimes. In some cases, increasing the density can reduce the skyrmion Hall angle while producing a velocity boost, which could be valuable for applications.

Auditory Efferent System Influences the Auditory Overshoot Phenomenon- An Auditory Brainstem Response Study in Guinea Pigs

Introduction: Detection of a brief tonal signal at the beginning of a longer masking noise is difficult, but it becomes easier when the onset of signal is delayed. This phenomenon is known as overshoot or temporal effect. Aiming of our study was to investigate the effect of the auditory efferent nerves (AENs) function on the auditory electrophysiological overshoot, further introducing an objective tool examining one of the AENs performances. Therefore, the effect and the trend of changes induced by low and high-frequency stimuli on electrophysiological overshoot in different delay onset time (DOTs) between the signal and the noise before and after dissecting the AENs were studied. Methods: Right internal auditory canals were exposed in 16 young male guinea pigs weighing 250 to 350 g. The inferior and posterior vestibular nerves that are known to carry AENs were transected in half of the subjects. Then, the ABR waveforms were recorded at 16 & 8 kHz tone burst stimuli at 0, 30, 60, 100 ms DOTs relative to wide-band noise. The value of latency of ABR waves I and III were compared among the different DOTs and five signal-to-noise ratios (SNRs) before and after the surgery. Results: By increasing DOTs, the latency of ABR waves I& III decreased in the control group before and after the surgery and the case group before surgery at 16 kHz. However, the observed overshoot-like effect disappeared after the surgery in the case group. The wave's latency I& III increased from 0 to 30 ms, remained approximately constant from 30 to 60ms, and then began to decrease toward 100 ms DOTs. However, none of the measurements at 8 kHz, before and after surgery at both groups showed an overshoot effect. Conclusion(s): By using the ABR paradigm, the overshoot phenomenon disappeared after the transection of AENs. The results confirmed the role of the efferent system on auditory overshoot. Therefore, an objective tool to measure auditory efferent function is provided.

Physics based compact modeling of symmetric double gate MOS transistors with high mobility III-V channel material

In this work, we report a physics-based core model of surface potential, inversion charge, and drain current of a symmetric double-gate MOSFET with high mobility III-V channel material. The model efficiently captures all essential device physics of III-V MOSFETs. The carrier quantization effect inside the quantum well formed between oxide and channel region, is modeled by solving time-independent Schrödinger wave equation. The surface potential and inversion charge are obtained from the explicit solution of the Poisson and Schrödinger equation. A first-order correction has been applied to incorporate the modifications in sub-band energy due to applied gate bias voltages. The conduction band non-parabolicity effect is also included in our proposed model. The drain current has been derived using drift-diffusion transport including the velocity overshoot effect. The core model is free from any empirical parameters. The model predicted results have been validated with self-consistent Schrödinger-Poisson solver and commercial device simulator (TCAD) for different channel thicknesses, effective masses, a wide range of gate and drain bias voltages, and different non-parabolicity factor. The model predicted results are found to be in reasonable agreement with numerical simulation data.

Three corrections for overshoot effect improved the dose for step-and-shoot intensity-modulated radiation therapy

We measured the overshoot effect in a linac and reduced it using block correction, reverse-sequence correction, and index correction. A StarTrack detector was used on a Varian iX. Five segments, 1 × 10 cm2 in area, were designed; the centers were at -4, -2, 0, 2, and 4 cm on the x axis for measuring the overshoot effect on a 10 × 10 cm2 collimator setting. Block correction was applied to two segments. The first was on the new first segment at -6 cm, and the other was on the new last segment at 6 cm. Both two new segments were obtained from the 10 × 10 cm2 collimator setting. The order of segments was reversed in reverse-sequence correction. Reverse-sequence correction averages the dose at every segment after two irradiations. When we used MLC Shaper, index correction reduced the first segment's index (cumulative radiation occupation) by 60% and increased the last segment's radiation occupation by 60% in a new MLC.log file. As for relative dose, the first segment had an overdose of 52.4% and the last segment had an underdose of 48.6%, when irradiated at 1 MU at 600 MU/min. The relative doses at the first segment, irradiated at 1 MU, after block correction, reverse-sequence correction, and index correction were applied decreased from 152.5% to 95.1%, 104.8%, and 100.1%, respectively. The relative doses at the last segment, irradiated at 1 MU, after block correction, reverse-sequence correction, and index correction were applied increased from 48.6% to 97.3%, 91.1%, and 95.9%, respectively. The overshoot effect depended on the speed of irradiation. High irradiation speeds resulted in notable overdosing and underdosing at the first and last segments, respectively. The three corrections mitigated the overshoot effect on dose. To save time and effort, the MLC.log file should be edited with a program in the future.

Comprehensive Studies on Steady-State and Transient Electronic Transport in In0.52Al0.48As

High electron mobility transistors (HEMT) built using In\textsubscript{0.52}Al\textsubscript{0.48}As/In\textsubscript{0.53}Ga\textsubscript{0.47}As on InP substrates are a focus of considerable experimental studies due to their favourable performance for microwave, optical and digital applications. We present a detailed and comprehensive study of steady state and transient electronic transport in In\textsubscript{0.52}Al\textsubscript{0.48}As with the three valley model using the semi-classical ensemble Monte Carlo method and including all important scattering mechanisms. All electronic transport parameters such drift velocity, valley occupation, average electron energy, ionization coefficient and generation rate, electron effective mass, diffusion coefficient, energy and momentum relaxation time are extracted rigorously from the simulations. Using these, we present a complete characterization of the transient electronic transport showing the variation of drift velocity with distance and time. We have then estimated the optimal cut-off frequencies for various device lengths via the velocity overshoot effect. Our analysis shows that for device lengths shorter than $700$ nm, transient effects are significant and should be taken into account for optimal device designs. As a critical example, at length scales of around $100$ nm, we obtain a significant improvement in the cut-off frequency from $261$ GHz to $663$ GHz with the inclusion of transient effects. The field dependence of all extracted parameters here can prove to be helpful for further device analysis and design.