Impulse Times Research Articles

Impulse Control: Boolean Programming and Numerical Algorithms

A numerical algorithmic approach to the impulse control problem is considered. Impulse controls are modelled by Boolean binary variables. The impulse Gateaux derivatives for impulse times, impulse volumes and Boolean variables are derived, and these are applied to the numerical algorithms. These algorithms require significantly less computation time and memory storage than the quasi-variational inequalities by Bensoussan-Lions. By using our algorithms, complicated models of hybrid or constrained systems can be more easily treated numerically than by using Pontryagin's Minimum Principle. Numerical experiments are performed for models on capacity expansion in a manufacturing plant, and on impulse control of Verhulst systems and Lotka-Volterra systems; the results confirm the effectiveness of the proposed method

54.1: Comparison of LCD Motion Blur Reduction Methods using Temporal Impulse Response and MPRT

This paper describes the relation between temporal display response and motion blur for several motion blur reduction methods (higher frame rate, scanning backlight, black data insertion). The impulse responses and Motion Picture Response Times (MPRTs) of these methods are calculated, compared and discussed.

엘리베이터 속도 패턴의 퍼지 제어

본 논문에서는 엘리베이터 속도 패턴을 결정하는데 중요한 2개의 요소인 편안한 승차감과 빠른 운송속도를 가지며 교통량 변화에 따른 다양한 속도 패턴을 제공 할 수 있는 새로운 속도 패턴 발생 방법을 제안한다. 기동과 정지 시에 변속 충격을 줄이기 위해서 가속과 감속 시간을 적절히 조정하고, 운송능력을 향상시키기 위해서 교통량 변화에 맞춰서 저크를 조정한다. 2입력 1출력의 퍼지 추론 시스템을 사용하여, 제안한 속도패턴을 가진 엘리베이터 시스템을 정밀 제어한다. In this paper, a new speed pattern generation method is proposed to offer various speed patterns for the traffic changers, with the comfortable driving and the rapid transportation speed that are two important factors to determine elevator speed pattern. To reduce the speed shift impulse, acceleration and deceleration times are appropriately adjusted to the elevator system when start and stop. In order to improve transportation capability, the jerk is also adjusted to the traffic change. Using fuzzy inference system with 2 input variables and 1 output, the elevator system controls precisely, with the proposed speed pattern.

Optimal control of volterra equations with impulses

We consider an optimal control problem for a system governed by a Volterra integral equation with impulsive terms. The impulses act on both the state and the control; the control consists of switchings at discrete times. The cost functional includes both, an integrated cost rate (continuous part) and switching costs at the discrete impulse times (discrete part). We prove necessary optimality conditions of a form analogous to a discrete maximum principle. For the particular case of a system governed by impulsive ordinary differential equations, we obtain an impulsive maximum principle as a special case of the necessary optimality conditions for impulsive Volterra equations.

Tetrahedron Formation Control

Spacecraft flying in tetrahedron formations are excellent instrument platforms for electromagnetic and plasma studies. A minimum of four spacecraft - to establish a volume - is required to study some of the key regions of a planetary magnetic field. The usefulness of the measurements recorded is strongly affected by the tetrahedron orbital evolution. This paper considers the preliminary development of a general optimization procedure for tetrahedron formation control. The maneuvers are assumed to be impulsive and a multi-stage optimization method is employed. The stages include targeting to a fixed tetrahedron orientation, rotating and translating the tetrahedron and/or varying the initial and final times. The number of impulsive maneuvers citn also be varied. As the impulse locations and times change, new arcs are computed using a differential corrections scheme that varies the impulse magnitudes and directions. The result is a continuous trajectory with velocity discontinuities. The velocity discontinuities are then used to formulate the cost function. Direct optimization techniques are employed. The procedure is applied to the Magnetospheric Multiscale Mission (MMS) to compute preliminary formation control fuel requirements.

Multiple positive solutions for first order nonlinear impulsive integro-differential equations in a Banach space

By using the fixed point index theory, the author obtains the existence of two positive solutions for a boundary value problem of first order nonlinear impulsive integro-differential equations on an infinite interval with an infinite number of impulsive times in a real Banach space.

Effects of unsteady scalar dissipation rate on ignition of non-premixed hydrogen/air mixtures in counterflow

As a step toward understanding the effects of a turbulent environment on ignition delay, the effect of impulsive strain forcing on the autoignition of non-premixed hydrogen/air mixtures is studied numerically using a one-dimensional unsteady opposed-flow code with detailed chemistry. The sensitivity of ignition kernel growth to changes in the scalar dissipation rate during the ignition process is studied at conditions in the second and third ignition limits. The sensitivity of the kernel growth is quantified by examining the time evolution of key radical species as well as their reaction and flow flux balances over a range of impulse amplitudes and times. Results show that transient ignition in both the second and the third limits is sensitive to changes in scalar dissipation rate. Increases in ignition delay of as much as five times are observed, depending upon the impulsive forcing amplitude and timing. For a given impulse amplitude, kernels that have accumulated more radicals at a given time during induction are found to ignite much sooner, indicating that the time history of the kernel radical pool relative to the impulse time is important. Furthermore, kernels are found to be able to survive excursions in the scalar dissipation rate to values that far exceed the steady ignition state. The increase in ignition delay in both limits is attributed to a shorter residence time of radicals in the kernel as measured by an instantaneous Damkohler number. A new ignition criterion based on the instantaneous Damkohler is found to be an accurate measure of predicting the ignitability under highly transient conditions.

Cadenced runs of impulse and hybrid control systems

AbstractImpulse differential inclusions, and in particular, hybrid control systems, are defined by a differential inclusion (or a control system) and a reset map. A run of an impulse differential inclusion is defined by a sequence of cadences, of reinitialized states and of motives describing the evolution along a given cadence between two distinct consecutive impulse times, the value of a motive at the end of a cadence being reset as the next reinitialized state of the next cadence.A cadenced run is then defined by constant cadence, initial state and motive, where the value at the end of the cadence is reset at the same reinitialized state. It plays the role of a ‘discontinuous’ periodic solution of a differential inclusion.We prove that if the sequence of reinitialized states of a run converges to some state, then the run converges to a cadenced run starting from this state, and that, under convexity assumptions, that a cadenced run does exist. Copyright © 2001 John Wiley & Sons, Ltd.

The stability of mechanical systems subjected to impulsive actions

Mechanical systems subjected to an impulsive load at set times are considered. The impulsive forces depend on generalized coordinates and cause variation of the generalized velocities of the system. Equations of this type describe the vibrations of structures due to seismic shocks, the dynamics of systems of rigid bodies on a moving train or a landing aircraft, etc. The instants of the impulsive action may have limit points, as in the case of shocks which attenuate in a geometric progression. Various problems related to the stability of motion will be discussed. First, general properties of solutions with infinitely many impulse times will be established, namely, their existence, uniqueness and the nature of their dependence on the parameters and initial conditions. The results obtained enable in particular, the linearization method to be used to investigate the stability. Particular attention is paid to non-linear Hamiltonian systems with generalized (impulsive) potential. It is shown that such systems possess a cononical phase flow, and KAM-theory may be used to investigate the stability. An important part of such investigations is the problem of constructing the stability domain in the first approximation, the solution of which frequently involves an analysis of Hill's equation. A series of sufficient conditions are obtained for the stability of the trivial solution of Hill's equation with periodic shocks, generalizing well-known criteria which are applicable to smooth systems. The example of a pendulum whose suspension point is given periodic equal vertical impulses is considered in detail.

On Impulse Control with Partial Observation

This paper presents an existence result for an impulse control problem with partial observation. The unobserved process evolves between any two successive impulse times as a Feller Markov process on a locally compact separable state space, and the observation process is of a signal + white noise type.

Short-latency scalp somatosensory evoked potentials and central spine to scalp propagation characteristics during peroneal and median nerve stimulation in multiple sclerosis

Peripheral (cauda-lumbar, wrist-Erb, Erb-cervical) and central (cauda-vertex, cervical-scalp) nervous impulse propagation velocities and times to peroneal and median nerve stimulation were investigated in 34 patients suffering from definite (17 cases), probable (6 cases) and possible (11 cases) forms of multiple sclerosis (MS). In 6 cases short- and intermediate-latency scalp somatosensory evoked potentials to peroneal nerve stimulation were recorded with ‘open’ (1–5000 Hz, −6 dB) bandpass filters and subsequently digitally filtered through a ‘narrow’ bandpass (200–5000 Hz, −6 dB). The lumbar response was abnormal in 2.95% of legs, while the Erb response was always within normal limits. The cauda-vertex conduction was altered in 75% of the examined limbs (86.2% definite, 58.3% probable, 63.6% possible MS). Absent scalp responses to peroneal stimulation were often encountered during narrow bandpass recording (54.9%), while a slowed central conduction was less frequent (33.3%). Scalp responses when recorded with open bandpass were always identifiable, being delayed in 3 out of 6 cases. In 5 of these the short-latency wavelets were either absent or showed a prolonged interpeak time even when open filter records were normal. Median nerve SEPs were altered in 60.3% of cases, more frequently because of a delayed scalp response or of a prolonged cervical-scalp conduction time than because of an absent cervical or scalp response. When peroneal and median nerve data were considered together, the rate of abnormality rose to 88.2% of patients. Due to their length, afferent pathways from the lower limb might suffer from a loss of high frequency impulse coding as an early sign of defective impulse propagation.

Comparison of cognitive tempo and time estimation by young boys.

The relationship between cognitive tempo and time estimation by young boys is investigated. Emphasis is on clarifying the physiological vs learned etiology of cognitive tempo on the assumption that a predilection to cortical excitation or inhibition can be indicated through time estimation. Significant differences between 20 impulsive and 20 reflective boys (aged 8--0 to 8--11) on estimates of reproduction time and a high correlation (-.49) between impulsive boys' response times and estimates of reproduction time were noted.

Some Characteristics of Ultra-Fast Time Structures Superimposed on Impulsive mm-Wave Bursts

SummaryThe use of increased sensitivity and temporal resolution at mm-wavelengths has revealed a number of novel features associated with solar activity (Kaufmann et al., 1979a). Of particular interest are the ultra-fast time structures superimposed on impulsive bursts. They are distinguished by time scales and repetition rates much shorter than the impulsive times scales. For weak bursts at λ = 13mm (i.e., few s.f.u.) the superimposed spikes are separated in time by several seconds. For moderate fluxes (i.e., 100 s.f.u.) the repetition rate of superimposed spikes is ~ 10–15 per second (i.e., time interval between two repeated spikes ~ 80 msec). For bursts larger than 500 s.f.u. the predicted times between repeated ultra-fast structures are shorter than 10 msec. Various examples have been studied with a time resolution better than 10 msec. (Kaufmann et al., 1979b). The impulsive flux level increases with the repetition rate of the ultra-fast component, following a nearly linear relationship. The simplest interpretation suggests that the injected spikes are associated with the bursting source function and are quasi-quantized in energy (Kaufmann et al., 1979b).

Underestimation of Children's Preferences for Signals of Correctness Using Selective Learning

Hypotheses investigated were that signals of correctness possess incentive properties and that selective learning underestimates incentive preferences. Forty middle-class fifth graders were divided into two groups. A competition group was presented with a selective learning task, with signals of correctness and pennies as competing incentives. As predicted, they preferred the signal of correctness over the penny. A signal of correctness group was given the same task but only signals of correctness as reward. As predicted, subjects exhibited better acquisition, yielded less impulsive choice times, and chose more signals of correctness than did the competitive group. Girls increased their choices of signals of correctness and yielded faster initial choice times than did boys, suggesting sex differences in preferences.

Neural pulse frequency modulation of an exponentially correlated Gaussian process

When the input to a Neural Pulse Frequency Modulation (NPFM) system is a stationary random process the output takes the form of a train of impulses for which the occurrence times and the intensities are stationary processes of a discrete type. Particularly, the impulse occurrence times constitute a stationary point process where the average impulse frequency (average number of impulses per unit time) becomes a reciprocal of the mean impulse period. Due to the inherent nature of the modulation procedure the determination of the mean impulse period transforms to a problem of computing the mean first passage time of a random process which is not necessarily Markovian. In this paper numerical solutions of the average impulse frequency of a Neural Pulse Frequency Modulation System are obtained for the case of an exponentially correlated Gaussian input. Monte Carlo computer simulations substantiate the theoretically obtained results.

Impulse Rise and Fall Times of Biplanar Vacuum Photodiodes

The impulse rise and fall times of biplanar vacuum photodiodes are experimentally investigated by the use of a single ultrashort laser pulse from a train of mode-locked pulses. It was confirmed that the impulse rise time is a function of the photoelectrons' transit time from photocathode to anode, and that the impulse fall time is 2.2 times the capacitance of the photodiode and the resistive component of the load.