Time Response Characteristics Research Articles

Magnetoelectric Effect for Rotational Parameters Detection

The magnetoelectric (ME) effect has been successfully demonstrated in the potential device applications of energy harvesters, magnetic sensors, current sensors, microwave and millimeter-wave multiferroic devices, miniature antennas, and even medical applications. To further investigate the role of ME effect in rotational parameters detection, this paper presents an ME rotational parameter sensor consisting of a magnetostrictive/piezoelectric laminated composite (MPLC) and a multi-pole magnetic ring. The relationship between the proposed sensor’s output signal and the rotational parameters has been analyzed. The output frequency is directly proportional to the rotational speed, and the waveform has a good sin property. In a word, based on the proposed sensor, the rotational speed can be measured by determining the frequency of the output signal, and the rotational position can be detected by the phase discrimination. As the MPLC has the characteristics of high sensitivity and quick response, the starting and stopping times and the eccentricity of rotating pieces can also be measured by the proposed ME rotational parameter sensor.

О некоторых закономерностях и особенностях российской пожарной статистики

The study of statistical reports including fire statistics reports, allow us to find interesting regularities, useful for specialists. It requires reliable and complete statistics, which do not always meet these re-quirements. The world fire statistics has received a powerful impetus to the development and improvement in recent decades. Many countries have begun to publish detailed annual statistical reports regarding the situa-tion with fires in their own countries and fire services activities (USA, France, UK, Italy and many others). It is possible to regularly conduct detailed comparative analysis and study the situation with fires in the world. Russian fire statistics is developing in the same direction and annually publishes informative reports that allow to get a lot of interesting information regarding the situation with fires and fire service activities in Russia. Some statistical regularities that can be extracted from these reports, are in the focus of this article. These statistical regularities may be interesting to specialists of fire safety. The article presents the trends in the number of fires and small fires in Russia in 2009-2015, the trends in the average fire losses per one fire in the cities and rural areas in 2006-2015, the trends in temporal characteristics of fire units activities (the average response time and the average time of extingu-ishing of fires) in 2007-2015. It is shown that in spite of a significant reduction in the number of fires and the temporal cha-racteristics (response time and extinguishing time) of fire units activities the fire losses are growing rapidly in the cities and in the rural areas.

Trapping States in SiO<sub>2</sub>/GaN MOS Capacitors Fabricated on Recessed AlGaN/GaN Heterostructures

In this work, the different nature of trapping states in metal-oxide-semiconductor (MOS) capacitors fabricated on recessed AlGaN/GaN heterostructures has been investigated. In particular, the origin of both fast and slow states has been elucidated by frequency dependent conductance measurements. Using post deposition annealing in forming gas, which is known to induce hydrogen incorporation at the interface, allowed to ascribe the fast traps (with characteristic response time in the range of 5–50 μs) to SiO2/GaN interface states and the slow traps (50–100 μs) to “border traps” located few nanometers inside the SiO2 layer. The results can be useful to predict the behavior of GaN switching devices, like hybrid MOSHEMTs.

Beyond the ponderomotive limit: Direct laser acceleration of relativistic electrons in sub-critical plasmas

We examine a regime in which a linearly polarized laser pulse with relativistic intensity irradiates a sub-critical plasma for much longer than the characteristic electron response time. A steady-state channel is formed in the plasma in this case with quasi-static transverse and longitudinal electric fields. These relatively weak fields significantly alter the electron dynamics. The longitudinal electric field reduces the longitudinal dephasing between the electron and the wave, leading to an enhancement of the electron energy gain from the pulse. The energy gain in this regime is ultimately limited by the superluminosity of the wave fronts induced by the plasma in the channel. The transverse electric field alters the oscillations of the transverse electron velocity, allowing it to remain anti-parallel to laser electric field and leading to a significant energy gain. The energy enhancement is accompanied by the development of significant oscillations perpendicular to the plane of the driven motion, making trajectories of energetic electrons three-dimensional. Proper electron injection into the laser beam can further boost the electron energy gain.

Nearshore sandbar rotation at single‐barred embayed beaches

AbstractThe location of a shore‐parallel nearshore sandbar derived from 7 years of video imagery data at the single‐barred embayed Tairua Beach (NZ) is investigated to assess the contribution of barline rotation to the overall morphodynamics of sandbars in embayed environments and to characterize the process of rotation in relation to external conditions. Rotation induces cross‐shore barline variations at the embayment extremities on the order of magnitude of those induced by alongshore uniform cross‐shore migration of the bar. Two semiempirical models have been developed to relate the barline cross‐shore migration and rotation to external wave forcing conditions. The rotation model is directly derived from the cross‐shore migration model. Therefore, its formulation advocates for a primary role of cross‐shore processes in the rotation of sandbars at embayed beaches. The orientation evolves toward an equilibrium angle directly related to the alongshore wave energy gradient due to two different mechanisms. Either the bar extremities migrate in opposite directions with no overall cross‐shore bar migration (pivotal rotation) or the rotation relates to an overall migration of the barline which is not uniform along the beach (migration‐driven rotation). Migration and rotation characteristic response times are similar, ranging from 10 to 30 days for mild and energetic wave conditions and above 200 days during very calm conditions or when the bar is located far offshore.

Evidence and Implications of Nonlinear Flood Response in a Small Mountainous Watershed

AbstractThis study investigates the impact of event characteristics on runoff dynamics during extreme flood events observed in an 8.5-km2 experimental watershed located in South Korea. A high-quality data set containing the 31 most extreme flood events with event rainfall in excess of 50 mm were analyzed using an event-based rainfall-runoff model; the revitalized flood hydrograph (ReFH) routinely used for design flood estimation in the United Kingdom. The ReFH model was fitted to each event in turn, and links were investigated between each of the two model parameters controlling runoff volume and response time, respectively, and event characteristics such as rainfall depth, duration, and intensity, and also antecedent soil moisture. The results show no link between the parameter controlling runoff volume and any of the event characteristics, but identified a dependence between response time and rainfall depth. These results show that the linear unit hydrograph fails to adequately represent a reduction in ...

Subpicosecond Nonlinear Plasmonic Response Probed by Femtosecond Optical Pulses

The hydrodynamic model of the electron transport in the channel of a nanoscale field effect transistors predicts that three different electron transport regimes – collision-dominated, ballistic, and viscosity dominated – determine the ultimate response time of the semiconductor device depending on its length, momentum relaxation time, and viscosity. The characteristic response times of ultra-short channel transistors are in the subpicosecond range. We now report on a new measurement technique with a greatly enhanced sensitivity using optical band-to-band pulses with a controlled delay. The measurements using this new electro-optic sampling and hydrodynamic modeling reveal the ultra-fast transistor plasmonic response at the time scale much shorter than the electron transit time.

압력센서 개발을 위한 탄소 나노 튜브 기반 지능형 복합소재 전왜 특성 연구

This paper presents a preliminary study on the pressure sensing characteristics of smart nano composites made of MWCNT (multi-walled carbon nanotube) to develop a novel pressure sensor. We fabricated the composite pressure sensor by using a solution casting process. Made of carbon smart nano composites, the sensor works by means of piezoresistivity under pressure. We built a signal processing system similar to a conventional strain gage system. The sensor voltage outputs during the experiment for the pressure sensor and the resistance changes of the MWCNT as well as the epoxy based on the smart nano composite under static pressure were fairly stable and showed quite consistent responses under lab level tests. We confirmed that the response time characteristics of MWCNT nano composites with epoxy were faster than the MWCNT/EPDM sensor under static loads.

Contribution of myosin II activity to cell spreading dynamics.

Myosin II activity and actin polymerization at the leading edge of the cell are known to be essential sources of cellular stress. However, a quantitative account of their separate contributions is still lacking; so is the influence of the coupling between the two phenomena on cell spreading dynamics. We present a simple analytic elastic theory of cell spreading dynamics that quantitatively demonstrates how actin polymerization and myosin activity cooperate in the generation of cellular stress during spreading. Consistent with experiments, myosin activity is assumed to polarize in response to the stresses generated during spreading. The characteristic response time and the overall spreading time are predicted to determine different evolution profiles of cell spreading dynamics. These include, a (regular) monotonic increase of cell projected area with time, a non-monotonic (overshooting) profile with a maximum, and damped oscillatory modes. In addition, two populations of myosin II motors are distinguished based on their location in the lamella; those located above the major adhesion zone at the cell periphery are shown to facilitate spreading whereas those in deeper regions of the lamella are shown to oppose spreading. We demonstrate that the attenuation of myosin activity in the two regions may result in reciprocal effects on spreading. These findings provide important new insight into the function of myosin II motors in the course of spreading.

Harmony Search Optimized Fractional Order PID Controller for Voltage Control of Fuelcell

In vehicular applications, fuel cell operates under varying load conditions. Sudden load variations may affect the performance of the fuel cell. The performance of a fuel cell depends on several parameters like input reactant flow rate, partial pressure of the reactants, stack temperature and membrane hydration which can be controlled by varying range of current. Unexpected load variations can cause reactant starved condition that leads to membrane dehydration and failure of the fuel cell. So Voltage Control is an important issue to be considered seriously while implementing any applications with fuel cells. This paper considers Proton Exchange Membrane Fuel Cell (PEMFC) which is widely used for vehicular applications. The aim of this paper is to track the output voltage of fuel cell by varying the input flow rate of hydrogen with the help of a Harmony search optimized Fractional Order PID (FOPID) Controller. The above Controller is implemented and simulated in MATLAB SIMULINK by considering the State space Model of Fuel cell. The performance of the proposed controller is analyzed by (i) Calculating the system (ii) Estimating the Time Response Characteristics of HS tuned FOPID Controller. Finally the simulation results are compared with that of existing PID Controller.

Oxygen, facies, and secular controls on the appearance of Cryogenian and Ediacaran body and trace fossils in the Mackenzie Mountains of northwestern Canada

The causes behind the appearance of abundant macroscopic body and trace fossils at the end of the Neoproterozoic Era remain debated. Iron geochemical data from fossiliferous Ediacaran successions in Newfoundland suggested that the first appearances correlated with an oxygenation event. A similar relationship was claimed to exist in the Mackenzie Mountains, Canada, although later stratigraphic studies indicated that the sections analyzed for geochemistry were incorrectly correlated with those hosting the fossils. To directly connect fossil occurrences with geochemistry in the Mackenzie Mountains, we conducted a multiproxy iron, carbon, sulfur, and trace-element geochemical analysis of stratigraphic sections hosting both the Cryogenian “Twitya discs” at Bluefish Creek as well as Ediacaran fossils and simple bilaterian traces at Sekwi Brook. There is no clear oxygenation event correlated with the appearance of macroscopic body fossils or simple bilaterian burrows; however, some change in environment—a potential partial oxygenation—is correlated with increasing burrow width higher in the Blueflower Formation. Data from Sekwi Brook suggest that these organisms were periodically colonizing a predominantly anoxic and ferruginous basin. This seemingly incongruent observation is accommodated through accounting for differing time scales between the characteristic response time of sedimentary redox proxies versus that for ecological change. Thus, hypotheses directly connecting ocean oxygenation with the appearance of macrofossils need not apply to all areas of a heterogeneous Ediacaran ocean, and stably oxygenated conditions on geological time scales were not required for the appearance of these Avalon-assemblage Ediacaran organisms. At least in the Mackenzie Mountains, the appropriate facies for fossil preservation appears to be the strongest control on the stratigraphic distribution of macrofossils.

Polarizer-free liquid crystal display with double microlens array layers and polarization-controlling liquid crystal layer.

We propose a polarizer-free liquid crystal display (LCD) consisting of two microlens array (MLA) layers, a twisted nematic (TN) LC layer, and two light-blocking masks. By changing the polarization state, focal length of the LCD can be controlled. Since two light-blocking masks have a circular stop pattern and a complementary open pattern, entire gray-scale spectrum may be realized by controlling the intensity of light passing through masks. Ultimately, fast response time characteristics could be achieved due to the alignment of LC molecules on the flat MLA surface.

Quantitative Determination of Response Time and Time-Varying Characteristics of Surge Protective Devices

This paper proposes an effective test setup and method for quantitative determination of critical parameters of surge protective devices (SPDs) when excited by nanosecond level pulse (normally rise time less than 2 ns). The experimental results of SPDs validate the accuracy and reliability of the proposed method. By using the proposed method, the response time and time-varying response characteristics can be evaluated; meanwhile, the incoming voltage and residual voltage of SPDs can be retrieved by simple mathematical operations. These parameters obtained from the proposed method are critical to the device selection when designing the fast response protective module and examining the performance of SPDs by the manufacturers.

LPG sensing performance of CuO–Ag2O bimetallic oxide nanoparticles

In the present article, we synthesized CuO–Ag2O bimetallic oxide nanoparticles by using microwave assisted and solid state diffusion routes. The structural, morphological, optical and thermal study of as-synthesized materials were done through X-ray diffractometer (XRD), scanning electron microscope (SEM), Fourier transform infrared (FTIR), ultraviolet–visible (UV–vis) and thermogravimetric analysis (TGA), respectively. Comparatively different sensing parameters such as sensing response at room temperature, operating temperature, response and recovery time and stability characteristics were investigated and discussed for liquefied petroleum gas (LPG). The CuO–Ag2O bimetallic oxide nanoparticles synthesized by microwave assisted route shows good gas sensing properties.

Experimental investigation of the effect of polymer matrices on polymer fibre optic oxygen sensors and their time response characteristics using a vacuum testing chamber and a liquid flow apparatus

Very fast sensors that are able to track rapid changes in oxygen partial pressure (PO2) in the gas and liquid phases are increasingly required in scientific research – particularly in the life sciences. Recent interest in monitoring very fast changes in the PO2 of arterial blood in some respiratory failure conditions is one such example. Previous attempts to design fast intravascular electrochemical oxygen sensors for use in physiology and medicine have failed to meet the criteria that are now required in modern investigations. However, miniature photonic devices are capable of meeting this need. In this article, we present an inexpensive polymer type fibre-optic, oxygen sensor that is two orders of magnitude faster than conventional electrochemical oxygen sensors. It is constructed with biologically inert polymer materials and is both sufficiently small and robust for direct insertion in to a human artery. The sensors were tested and evaluated in both a gas testing chamber and in a flowing liquid test system. The results showed a very fast T90 response time, typically circa 20ms when tested in the gas phase, and circa 100ms in flowing liquid.

A queueing-theoretical delay analysis for intra-body nervous nanonetwork

Nanonetworks is an emerging field of study where nanomachines communicate to work beyond their individual limited processing capabilities and perform complicated tasks. The human body is an example of a very large nanoscale communication network, where individual constituents communicate by means of molecular nanonetworks. Amongst the various intra-body networks, the nervous system forms the largest and the most complex network. In this paper, we introduce a queueing theory based delay analysis model for neuro-spike communication between two neurons. Using standard queueing model blocks such as servers, queues and fork-join networks, impulse reception and processing through the nervous system is modeled as arrival and service processes in queues. Simulations show that the response time characteristics of the model are comparable to those of the biological neurons.

Fluvio-deltaic avulsions during relative sea-level fall

Understanding river response to changes in relative sea level (RSL) is essential for predicting fluvial stratigraphy and source-to-sink dynamics. Recent theoretical work has suggested that rivers can remain aggradational during RSL fall, but field data are needed to verify this response and investigate sediment deposition processes. We show with field work and modeling that fluvio-deltaic systems can remain aggradational or at grade during RSL fall, leading to superelevation and continuation of delta lobe avulsions. The field site is the Goose River, Newfoundland-Labrador, Canada, which has experienced steady RSL fall of around 3–4 mm yr –1 in the past 5 k.y. from post-glacial isostatic rebound. Elevation analysis and optically stimulated luminescence dating suggest that the Goose River avulsed and deposited three delta lobes during RSL fall. Simulation results from Delft3D software show that if the characteristic fluvial response time is longer than the duration of RSL fall, then fluvial systems remain aggradational or at grade, and continue to avulse during RSL fall due to superelevation. Intriguingly, we find that avulsions become more frequent at faster rates of RSL fall, provided the system response time remains longer than the duration of RSL fall. This work suggests that RSL fall rate may influence the architecture of falling-stage or forced regression deposits by controlling the number of deposited delta lobes.

Solid-State Planar Edlc Design Enabled By Hydroxide-Conducting Polymer

Electrolytic capacitors are the current solution for 120 Hz power filtering. However such devices are bulky, which limits power electronics miniaturization. Electric double layer capacitors (EDLCs), often referred to by the product name Supercapacitor, have much higher volumetric charge storage and potentially should allow for a size reduction in the power electronics. For an EDLC to be capable of efficient AC line filtering, its impedance phase angle at 120 Hz must reach or be close to -90 degree. The very first EDLC that met this requirement was fabricated using vertically-oriented graphene with a liquid KOH electrolyte [1]. Both series resistance and distributed charge storage were minimized to reach this level of performance. Further development has led to a planar interdigitated cell design, which offers volumetric advantages and a simple approach for series-connecting cells [2]. With this design, polymer electrolytes are preferred since they can cover each planar cell without flowing to an adjacent cell. In the past, we have demonstrated a tetraethylammonium hydroxide (TEAOH)-based polymer electrolyte system that outperformed the KOH-based polymer electrolytes [3]. In this study, we leveraged the TEAOH polymer electrolyte and the vertically-oriented graphene to demonstrate solid-state planar EDLC cells. Impedance behavior of the cells at both room temperature and elevated temperatures was investigated. Two polymer electrolyte systems based on TEAOH were studied: (a) TEAOH-polyvinyl alcohol (TEAOH-XLPVA); and (b) TEAOH- polyacrylamide (TEAOH-PAM). Utilizing these polymer electrolytes, we assembled solid-state EDLC cells using vertically-oriented graphene electrodes. These solid-state devices were first tested at room temperature for aging stability and then at higher temperature for thermal stability. Figure 1 shows three plots of capacitance versus frequency for TEAOH-based electrolyte solid-state EDLCs. The capacitance values were calculated assuming a series-RC circuit model. While both TEAOH-PAM-based and TEAOH-XLPVA-based electrolyte cells showed capacitive behavior, the former exhibited higher initial capacitance than the latter (38 vs. 32 μF at 120 Hz). Although both capacitors showed slightly reduced capacitance after ca.25 days storage without packaging (Fig. 1a), both capacitors demonstrated good shelf life at room temperature. Further evaluations of the thermal stability of these capacitors at elevated temperatures were performed at temperatures up to 110 oC (Fig. 1b and 1c). Capacitance increased with increasing temperature for both solid-state electrolytes. A detailed analysis including comparisons will be presented. Capacitor equivalent series resistance and characteristic response times will be discussed.

Neurocognitive intra-individual variability in mood disorders: effects on attentional response time distributions.

Attentional impairment is a core cognitive feature of major depressive disorder (MDD) and bipolar disorder (BD). However, little is known of the characteristics of response time (RT) distributions from attentional tasks. This is crucial to furthering our understanding of the profile and extent of cognitive intra-individual variability (IIV) in mood disorders. A computerized sustained attention task was administered to 138 healthy controls and 158 patients with a mood disorder: 86 euthymic BD, 33 depressed BD and 39 medication-free MDD patients. Measures of IIV, including individual standard deviation (iSD) and coefficient of variation (CoV), were derived for each participant. Ex-Gaussian (and Vincentile) analyses were used to characterize the RT distributions into three components: mu and sigma (mean and standard deviation of the Gaussian portion of the distribution) and tau (the 'slow tail' of the distribution). Compared with healthy controls, iSD was increased significantly in all patient samples. Due to minimal changes in average RT, CoV was only increased significantly in BD depressed patients. Ex-Gaussian modelling indicated a significant increase in tau in euthymic BD [Cohen's d = 0.39, 95% confidence interval (CI) 0.09-0.69, p = 0.011], and both sigma (d = 0.57, 95% CI 0.07-1.05, p = 0.025) and tau (d = 1.14, 95% CI 0.60-1.64, p < 0.0001) in depressed BD. The mu parameter did not differ from controls. Increased cognitive variability may be a core feature of mood disorders. This is the first demonstration of differences in attentional RT distribution parameters between MDD and BD, and BD depression and euthymia. These data highlight the utility of applying measures of IIV to characterize neurocognitive variability and the great potential for future application.

The Effect of a Protective Overcoat on Mixed-Potential Sensor Response

Nitrogen oxide (NOx) and ammonia (NH3) sensing technology is being developed for application in vehicle emissions monitoring of diesel and lean-burn gasoline engines. In lean-burn engines, Selective Catalyst Reduction (SCR) utilizes NH3 to reduce NOx. The purpose of the NH3 sensor is to ensure that the NH3 is completely consumed in the NOx reduction reaction, and it is not emitted from the tailpipe. Both the NOx and NH3 sensors described herein are mixed-potential sensors that measure the non-nernstian potential created at an electrode/electrolyte interface exposed to a mixture of reducing/oxidizing gases. The NOx sensor is composed of La0.8Sr0.2CrO3 (lanthanum strontium chromite) and Pt electrodes with a YSZ electrolyte and a protective porous ceramic overcoat. The NH3 sensor is composed of Au/Pd and Pt electrodes with a YSZ electrolyte and protective overcoat. The purpose of the overcoat is to protect the electrodes from contaminants such as heavy metals and water present in harsh exhaust environments. We examine the effect of the protective overcoat on the sensor performance. Preliminary data on the NOx sensors indicates that the overcoat serves as a thermal blanket; decreasing the temperature difference observed between the heater and the sensing element in bare sensors. Sensing characteristics of response time, selectivity and sensitivity will be compared and discussed.