Effect Of Rise Time Research Articles

An Approximate Analytical Formulation for the Rise-Time Effect on Dynamic Structural Response Under Column Loss

Dynamic progressive collapse analysis of building structures is usually conducted under sudden column loss conditions. The time length required for disabling the failed column is defined as the rise time. The rise-time effect on the maximum dynamic response of building frames under column loss is investigated in this study. Based on the work-energy principle, an approximate analytical formulation for the maximum dynamic response is derived considering the rise-time effect. The force- and displacement-based dynamic increase factors (DIFs) of a single degree-of-freedom model and a clamped steel beam are used to assess the accuracy and validity of the proposed formulation. Analysis results indicate that the DIFs decrease with increased rise time. Also, the rise-time effect decreases with increased ductility demand. Practical application of the analytical formulation to regular building frames subjected to column loss is illustrated. Primary factors related to the extent of the rise-time effect on the column-loss response are identified for design consideration.

Effect of Stimulus Rise-Time on the Ocular Vestibular-Evoked Myogenic Potential to Bone-Conducted Vibration

The negative potential at 10 msec (called n10) of the ocular vestibular-evoked myogenic potential (oVEMP) recorded beneath the eyes in response to bone-conducted vibration (BCV) delivered to the skull at the midline in the hairline (Fz) is a new indicator of otolithic, and in particular utricular, function. Our aim is to find the optimum combination of frequency and rise-time for BCV stimulation, to improve the sensitivity of oVEMP testing in the clinic. We tested 10 healthy subjects with 6 msec tone bursts of BCV at three stimulus frequencies, 250, 500, and 750 Hz, at rise-times ranging between 0 and 2 msec. The BCV was delivered at Fz. The n10 response was significantly larger at the shorter rise-times, being largest at zero rise-time. In addition, we examined the effect of stimulus frequency in these same subjects by delivering 6 msec tone bursts at zero rise-time at a range of frequencies from 50 to 1200 Hz. The main effect of rise-time was significant with shorter rise-times leading to larger n10 responses and the Rise-Time × Frequency interaction was significant so that at low frequencies (100 Hz) shorter rise-times had a modest effect on n10 whereas at high frequencies (750 Hz) shorter rise-times increased n10 amplitude substantially. The main effect of frequency was also significant: The n10 response tended to be larger at lower frequency, being largest between 250 and 500 Hz. In summary, in this sample of healthy subjects, the most effective stimulus for eliciting oVEMP n10 to BCV at Fz was found to be a tone burst with a rise-time of 0 msec at low stimulus frequency (250 or 500 Hz).

Latency of tone-burst-evoked auditory brain stem responses and otoacoustic emissions: Level, frequency, and rise-time effects

Simultaneous measurement of auditory brain stem response (ABR) and otoacoustic emission (OAE) delays may provide insights into effects of level, frequency, and stimulus rise-time on cochlear delay. Tone-burst-evoked ABRs and OAEs (TBOAEs) were measured simultaneously in normal-hearing human subjects. Stimuli included a wide range of frequencies (0.5-8 kHz), levels (20-90 dB SPL), and tone-burst rise times. ABR latencies have orderly dependence on these three parameters, similar to previously reported data by Gorga et al. [J. Speech Hear. Res. 31, 87-97 (1988)]. Level dependence of ABR and TBOAE latencies was similar across a wide range of stimulus conditions. At mid-frequencies, frequency dependence of ABR and TBOAE latencies were similar. The dependence of ABR latency on both rise time and level was significant; however, the interaction was not significant, suggesting independent effects. Comparison between ABR and TBOAE latencies reveals that the ratio of TBOAE latency to ABR forward latency (the level-dependent component of ABR total latency) is close to one below 1.5 kHz, but greater than two above 1.5 kHz. Despite the fact that the current experiment was designed to test compatibility with models of reverse-wave propagation, existing models do not completely explain the current data.

Temporal and Spatial Field Dynamics in Shielded Writer: A Micromagnetic Modeling Study

The characteristics of spatial and temporal field distributions are presented for wrap-around-shielded perpendicular magnetic recording writers. Micromagnetic modeling simulations are conducted to study the effects of shield thickness and the magnetization on the shield-related side field. An improvement of side field is found with the thicker shield thickness and higher saturation magnetization. The maximum side field is spatially and time dependent during the dynamic writing process. The side field reaches the maximum around the transitions, where the write field from the main pole is at the minimum. In addition, the write current rise-time effect on the side field is investigated.

Simple asymptotic forms for Sommerfeld and Brillouin precursors

This article mainly deals with the propagation of step-modulated light pulses in a dense Lorentz medium at distances such that the medium is opaque in a broad spectral region including the carrier frequency. The transmitted field is then reduced to the celebrated precursors of Sommerfeld and Brillouin, far apart from each other. We obtain simple analytical expressions of the first (Sommerfeld) precursor, whose shape only depends on the order of the initial discontinuity of the incident field and whose amplitude rapidly decreases with this order (rise-time effects). We show that, in a strictly asymptotic limit, the second (Brillouin) precursor is entirely determined by the frequency dependence of the medium attenuation and has a Gaussian or Gaussian-derivative shape. We point out that this result applies to the precursor directly observed in a Debye medium at decimetric wavelengths. When attenuation and group-delay dispersion both contribute to its formation, we establish a more general expression of the Brillouin precursor, containing the previous one (dominant-attenuation limit) and that obtained by Brillouin (dominant-dispersion limit) as particular cases. We finally study the propagation of square or Gaussian pulses, and we determine the pulse parameters optimizing the Brillouin precursor. Obtained by standard Laplace-Fourier procedures, our results are explicit and contrast in their simplicity those derived by the uniform saddle-point methods, from which it is difficult to retrieve our asymptotic forms.

Effect of Waveform Parameters on Pulsed Glow Discharge in Air

The nanosecond single pulse was employed here to generate a large volume glow discharge between the wire-plane electrodes in air. In order to find requirements on pulse waveform for generation of a large volume discharge at atmospheric pressure, the effect of pulse risetime, pulse width, and amplitude on glow discharge has been widely investigated in this paper. Results reveal that a large volume glow discharge can be generated in an inhomogeneous electric field under the single pulse with the faster risetime, the lower peak amplitude. The pulse width has almost no influence on the density of glow discharge, but which has a great influence on the transition from glow discharge to streamer discharge. A model of inter-shielding-effect has been proposed to explain the influence of waveform parameters on pulsed glow discharge.

Ti O 2 breakdown under pulsed conditions

Model studies of current conduction and breakdown in TiO2 were carried out. Our simulation results indicate that electrical breakdown of TiO2 under multiple-pulsed conditions can occur at lower voltages as compared to quasi-dc biasing. This is in agreement with recent experimental data and is indicative of a cumulative phenomena. We demonstrate that the lower breakdown voltages observed in TiO2 under pulsed conditions is a direct rise-time effect, coupled with successive detrapping at the grain boundaries.

Effects of Rise-time of Sound Stimulus on Auditory Evoked Magnetic Fields

Effects of Rise-time of Sound Stimulus on Auditory Evoked Magnetic Fields

Effect of head field rise time in perpendicular recording

An analytic recording model for the transition parameter and the nonlinear transition shift (NLTS) with the rise-time effect has been developed. In this model, the Schwartz-Christoffel transformation is used to calculate the combined image field from the single-pole writer and the soft underlayer. It is shown that both medium velocity and finite head-field rise-time increase the transition parameter. The NLTS for a dibit pattern increases with linear density, but decreases with medium velocity. A large transition parameter arises because a finite rise time reduces the record field-gradient as the bit time is reduced. For a dibit, the demagnetizing field from the first bit increases the transition interval of the dibit, while the write-time difference of the second bit and the reference bit decreases the interval.

Effect of pulse risetime on trigger homogeneity in single finger grounded gate nMOSFET electrostatic discharge protection devices

Effect of pulse risetime on trigger homogeneity in single finger grounded gate nMOSFET electrostatic discharge protection devices

Study of overwritten magnetization at the off-track position

Overwritten magnetization at the off-track position is studied by using micro-magnetic simulation employing the Landau-Lifshitz-Gilbert equation. The nominal track width was 600 nm and bit length was 100 nm. The first bit of overwritten magnetization at large off-track distances more than 50 nm is connected with the third bit at high frequencies. This is due to the decrease of the head field at the edge. The magnetization of the track edge is not quite reversed after completing overwrite. As the frequency increases, the head field decreases due to rise-time effects, so that overwrite cannot be completed normally. An increase in the resistivity of the head core material is useful in order to improve the off-track overwrite characteristics.

Rise-time effects in grounded gate nMOS transistors under transmission line pulse stress

In this paper, the clamping voltage of a grounded gate nMOS transistor (ggnMOSt) under transmission line pulse (TLP) stress has been analysed in detail by means of a mixed-mode simulator. We show that the breakdown voltage of the ggnMOSt measured in static conditions could underestimate the maximum voltage across the protection structure obtained by TLP stress, depending on the rise time of the applied pulse. In particular, the smaller the rise time, the larger the peak reached for the drain voltage. In this paper, we will show that this can be attributed to the charging of the overlap capacitance. The influence of the LDD implant option with respect to the standard implant has also been investigated. The relationship between the maximum clamping voltage and the triggering voltage of the parasitic bipolar transistor associated with the structure is explained. A simple analytical model describing the response of the device in the early phase of the forced pulse is presented.

Effects of stimulus intensity, risetime, and duration on autonomic and behavioral responding: Implications for the differentiation of orienting, startle, and defense responses

The effects of stimulus intensity, duration, and risetime on the autonomic and behavioral components of orienting, startle, and defense responses were investigated. Six groups of 10 students were presented with 15 white noise stimuli at either 60 or 100 dB, with controlled risetimes of either 5 or 200 ms, and at stimulus durations of 1 or 5 s (1 s only in the case of the 60-dB groups). A dishabituation stimulus consisting of a 1000 Hz tone was also presented. Measures consisted of skin conductance and heart rate, together with ratings of facial expressions and upper torso movement obtained using video recording. Increased intensity resulted in greater amplitudes and frequencies of electrodermal and behavioral responses, and a change from cardiac deceleration to acceleration. Faster risetimes elicited larger electrodermal responses, greater frequencies of eye-blinks, head and body movements, and larger cardiac accelerations. The effects of duration for the 100-dB stimuli were less clear-cut. Overall, the results are discussed in relation to the differentiation of orienting, startle, and defense responses.

Effects of stimulus intensity, risetime, and duration on autonomic and behavioral responding: Implications for the differentiation of orienting, startle, and defense responses

Effects of stimulus intensity, risetime, and duration on autonomic and behavioral responding: Implications for the differentiation of orienting, startle, and defense responses

Grasp stiffness as a function of grasp force and finger span.

The purpose of this study was to determine whether direct measurements of grasp stiffness agreed with stiffness inferred from the slopes of isovolitional force-space characteristics derived from previous grasp-effort matching data. Grasp stiffness for three-finger pinch was measured as a function of initial force and finger span using step displacements applied in a do-not-intervene paradigm. Subjects pinched a free-floating, motorized manipulandum in each hand and squeezed both with equal effort; one of the hands was perturbed at random. Stiffness was calculated from the initial and final steady-state values of force and span. The effects of step amplitude, rise-time, and initial load stiffness were investigated; grasp stiffness decreased significantly for larger steps, increased slightly for longer rise-times, and was unaffected by load stiffness. Grasp stiffness then was measured as a function of initial force and span using a single set of step parameters. Stiffness increased significantly in proportion to force but was changed only slightly by span. It was concluded that the perturbation and effort-matching measures of stiffness are not equivalent and represent different components of motor behavior.

Analytic termination metrics for pin-to-pin lossy transmission lines with nonlinear drivers

A significant percentage of the critical nets in high-performance systems are of the pin-to-pin type. To optimally design these nets such that signal integrity is preserved, efficient analytical metrics for transmission line termination are a valuable part of a system-level designer's toolset. Using the symbolic moment-based expressions in this paper, proper termination can be determined via a single-step procedure, without any preprocessing steps and/or time-domain simulations. Driver nonlinearities and effects of nonzero rise-time are also considered in the proposed termination methodology.

Effects of clamp rise-time on rat brain IIA sodium channels in Xenopus oocytes

The kinetic properties of wild-type rat brain IIa sodium channels in excised macropatches were studied using step depolarizations and ramp depolarizations to imitate the slow settling-time of voltage in two-electrode voltage clamp. Ramp depolarizations longer than 1 ms produce an increasing suppression of peak sodium current (I Na). Two rates of inactivation can be seen in macroscopic sodium current records from excised patches following both step and ramp depolarizations. During slow ramp depolarizations, reduction in peak I Na is associated with selective loss of the fastest rate of test-pulse inactivation. This change can be interpreted as resulting from inactivation of a separate sub-population of `fast mode' channels. The slow rate of test-pulse inactivation is relatively unaffected by changing ramp durations. These results are sufficient to explain the typically slow inactivation kinetics seen in two-electrode voltage clamp recordings of sodium channels in Xenopus oocytes. Thus, the kinetics of sodium channels expressed in Xenopus oocytes are not readily characterizable by two-electrode clamp because of the large membrane capacitance and resulting slow clamp settling time which artifactually selects for slow mode channels.

Risetime effects of HBM and square pulses on the failure thresholds of GGNMOS-transistors

For 0.8μm-GGNMOS transistors a lack of correlation between Human Body Model ESD testers conforming to current standards and transmission line pulsing (TLP) was observed. The paper demonstrates the influence of the initial 5%–40% risetime of TLP testers on the failure thresholds and failure signatures of transistors with single and multiple fingers.

Noninstantaneous, finite rise-time effects on the precursor field formation in linear dispersive pulse propagation

The effects of a noninstantaneous finite rise time on the transient field phenomena associated with dispersive pulse propagation are considered by use of the asymptotic description of the propagated plane-wave field in a single-resonance Lorentz model dielectric. The asymptotic description is presented for both an input hyperbolic tangent modulated signal with initial pulse envelope u(t) = [1 + tanh(βt)]/2 and an input raised cosine envelope signal with initial pulse envelope u(t) = 0 for t ≤ 0, u(t) = [1 − cos(βt)]/2 for 0 ≤ t ≤ π/β, and u(t) = 1 for t ≥ π/β. In both cases the parameter β is indicative of the rapidity of the initial rise time of the signal f(t) = u(t)sin(ωct) with input carrier frequency ωc. In the limit as β → ∞ both of these initial envelope functions approach the unit step function. The dynamical evolution of the propagated field is described by means of the dynamics of the saddle points in the complex ω plane that are associated with the complex phase function appearing in the integral representation of the propagated field and their interaction with the simple pole singularities of the spectrum ũ(ω − ωc) of the initial pulse envelope function. The analysis shows that the Sommerfeld and Brillouin precursor fields that are characteristic of the propagated field that is due to an input unit step function modulated signal will persist nearly unchanged for values of the rise-time parameter β of the order of δ or greater, where δ is the damping constant of the Lorentz model dielectric. As β is decreased below δ, the precursor fields become less important in the overall field structure and the field becomes quasi-monochromatic.

A systematic investigation on the use of time-dependent sensor signals in signal-processing techniques

Due to the lack of selectivity and separability of most common chemical sensors, the use of sensor arrays in combination with artificial neural network (ANN) signal processing is widely used. The time-dependent behaviour of gas sensors is one of the principal problems in signal-processing methods for sensor arrays. These time dependencies of semiconductor sensors can be classified into three main time domains: first, the rise time of the sensor after a sudden concentration change; secondly, the short-term drift after switching on; and finally, the long-term deterioration of the semiconductor material. An important improvement in the treatment of these time-dependent processes is the compensation of sensor rise time and short-term drift effects. The short-term drift of semiconductor sensors can be modelled and equalized by a preprocessing step. The rise-time effects can be reduced by measuring the sensor signals with a high measurement rate and training ANN's with these measurements. Preprocessing the sensor signal and applying the rise-time behaviour leads to an improvement of ANN generalization ability, and attains a minimum of prediction error after a minimum of time after gas exchange.