Showing papers on "Acceleration published in 1969"

Acceleration of particles reflected at a shock front

Abstract: Reflected particle acceleration at magnetospheric bow shock front attributed to interplanetary electric field

Calculation of response spectra from strong-motion earthquake records

Abstract: A numerical method for computing response spectra from strong-motion earthquake records is developed, based on the exact solution to the governing differential equation. The method gives a three to four-fold saving in computing time compared to a third order Runge-Kutta method of comparable accuracy. An analysis also is made of the errors introduced at various stages in the calculation of spectra so that allowable errors can be prescribed for the numerical integration. Using the proposed method of computing or other methods of comparable accuracy, example calculations show that the errors introduced by the numerical procedures are much less than the errors inherent in the digitization of the acceleration record.

Dynamic models of the human body

Abstract: : Some of the dynamic characteristics of the human body were analyzed and mathematical analogs that can be used to predict the response of the body to acceleration environments were developed. The background of the acceleration tolerance problem, the basic concepts of body dynamics, and the available experimental data were also reviewed. Both spinal and transverse dynamic models are presented together with the data used in obtaining frequency, damping, and breaking strength estimates. Other dynamic models are discussed more briefly since very little is known about the dynamic response to lateral and negative spinal accelerations. A discussion of the factors influencing the production of injury from exposure to accelerations is presented to indicate the difficulty in defining human tolerance to acceleration using the classical approach of graphs or simple critical G values that depend only upon the duration of the acceleration. The concept of relative probability of injury is developed in order to take into account the variations in the human structure and other factors that influence human tolerance to accelerations.

Antilock brake control

Abstract: AN ELECTRONIC CONTROL IS RESPONSIVE TO WHEEL ACCELERATION TO PRODUCE SIGNALS FOR EFFECTING ALTERNATING BRAKE RELEASE, HOLD, AND APPLICATION TO AVOID WHEEL LOCK. A WHEEL VELOCITY ERROR CIRCUIT COMPARES A WHEEL ACCELERATION SIGNAL TO A REFERENCE SIGNAL AND INTEGRATES THE DIFFERENCE TO CONTROL BRAKE RELEASE. A SIMILAR CIRCUIT RESPONSIVE TO THE WHEEL ACCELERATION SIGNAL AND ANOTHER REFERENCE SIGNAL CONTROLS BRAKE HOLD AND APPLICATION. A THIRD CIRCUIT VARIES THE REFERENCE SIGNALS TO OPTIMIZE THE CONTROL FUNCTION.

Digital Instrumentation for Angular Velocity and Acceleration

Abstract: An instrument is described for the measurement of angular velocity and angular acceleration of a rotating shaft, based upon an optical angular transducer and an associated operational digital (pulse rate) system. The angular transducer produces a pulse rate directly proportional to the instantaneous angular velocity and this quantity and its rate of change are processed by the pulse rate system and presented as parallel binary-coded decimal representations driving in-line digital displays. The operational digital system comprises essentially an electronic register controlling a variable rate pulse generator that tracks the input pulse rate in a frequency lock loop. Changes of loop frequency are brought about by changing the register contents by positive or negative correction pulses, and the rate at which these are supplied provides an accurate measure of acceleration or deceleration, respectively, provided that the loop is locked on and hence follows the changes of input pulse rate accompanying changes of angular velocity. The error correction pulse rate may be measured in a second frequency lock loop and the registers in the two loops used to control digital in-line decimal displays of angular velocity and acceleration, of ranges up to 10 000 r/min (±1 r/min) and 1000 r/min/s (±1 percent), respectively.

Apparatus for indicating changes in angular velocity, and vehicle braking systems employing such apparatus

Abstract: An apparatus for indicating changes in the angular velocity of a rotating body subjected to acceleration or deceleration, e.g. an automobile, has a velocity sensor producing an output having a frequency proportional to the angular velocity, a frequency-to-DC converter, a differentiator, a comparator for comparing the differentiated signal with a reference signal and for producing an output signal whenever the signals compared differ by a predetermined magnitude, which may be indicative of the onset of wheel-locking, and an actuator for reducing the deceleration (braking force) on the body in response to the comparator output signal.

An Absolute Micromanometer Using Diamagnetic Levitation

Abstract: A friction-free suspension in vacuo is provided for a graphite disk by magnetic induction. The disk rotates round a vertical line of force inside a properly designed stator; when the stator is cooled, a thermomolecular torque is developed and the acceleration thus given to the disk is measured by an automatic device. It is shown that this acceleration depends only on the geometrical design of the manometer and on the pressure, to which it is proportional. The manometer unit is passive, very small, and insensitive to vibrations and shocks affecting the vacuum setup. The lower limit of its range of measurement is less than 10−10 Torr. When stator cooling is removed, the disk is influenced only by a (smaller) molecular damping torque. This depends on the composition of the residual atmosphere; provided this is known, the magnitude of the damping can be computed a priori with good precision so that the instrument becomes a useful standard manometer for calibration in the 10−3 to 10−7 Torr range.

Tension regulation apparatus

Abstract: Apparatus for preventing a change in the tension in one region of a moving web from causing a change in the tension in another region of the web. An assembly which is movable translationally and rotationally by a force applied by a change in web tension at one of two engagement lines between the assembly and the web, has masses which are so distributed that a change in force applied at one of the lines produces substantially no acceleration of the assembly at the other engagement line.

Apparatus for controlled deceleration in numerical positioning

Abstract: A control system wherein a supervising computer is operable to observe acceleration and deceleration characteristics of the particular control system and then to compute optimum deceleration points with respect to subsequent commands to the system on the basis of the observed characteristics and to initiate deceleration of the system at the optimum points in executing the successive commands to the system.

Automatic flare and altitude hold system

Abstract: The invention disclosed by one representative embodiment herein includes an automatic pitch control system for an aircraft wherein a manual setting at any selected altitude produces a signal which is nulled out by a radar altimeter signal so as to automatically engage a pitch control flare circuit. Altitude error and altitude rate input signals are summed for control of the pitch axis of the aircraft so that after flare is completed, an altitude over varying terrain is held. Steep bank angles at the altitude are possible without the aircraft leaving the altitude in that a roll attitude signal is employed to oppose normal acceleration errors introduced by banking during coordinated turns. In addition, variable flare exponentials are described through the use of an altitude modification circuit.

Apparatus for measuring output characteristics of a rotary moving part

Abstract: The invention provides a dynamometer for measuring velocity, acceleration, torque and other quantities relative to the performance of a road vehicle or machine and comprises a plurality of roller assemblies on which the road wheels of the vehicle rest and which themselves form an inertia load or are connected to a flywheel forming an inertia load, each roller assembly driving a pulse generator producing a train of primary pulses which are gated with longer master control pulses to provide successive groups of primary pulses of the order of 0.1 seconds duration. Successive groups are operated upon by arithmetical circuits of an electrical computer to derive output signals representing velocity, acceleration or such other quantity as may be required to be determined, this or these quantities being stored in storage circuits which are constantly updated but can be held or frozen at a particular value by a trigger signal generated in response to attainment of a predetermined value of one of said quantities such as maximum value. The quantities are displayed digitally or graphically on a cartesian plotter unit.

Photographic study of solid propellants burning in an acceleration environment Final report

Abstract: Acceleration effects on aluminized composite solid propellants combustion by high speed color cinematography

Impact acceleration indicator

Abstract: A recording instrument which will produce a visual or electrical signal indicating when a preselected acceleration level has been experienced by the instrument, and will permanently record such impact so that when the instrument is attached to a package, a visual examination of the instrument will indicate whether or not the package has been dropped or subjected to a damaging impact.

Engine acceleration horsepower-metering system

Abstract: A magnetic pickup senses rotation of the engine ring gear to provide a frequency-related signal which is translated into a speed-related voltage signal. This voltage signal passes a first speed level w1 at the commencement of a predetermined time period Delta t, established by a multivibrator circuit. At the end of the time period Delta t a second speed level signal w2 is provided. The engine horsepower is then determined by the expression WHERE J represents the motor inertia and k is a constant, to provide a value indicative of the engine acceleration horsepower.

Electrohydraulic speed control system for cross compound turbine power plants

Abstract: AN ELECTROHYDRAULIC SPEED CONTROL SYSTEM FOR AUTOMATICALLY MATCHING THE SPEED OF THE LOW PRESSURE AND HIGH PRESSURE SHAFTS OF A CROSS COMPOUND STEAM TURBINE-GENERATOR. THE LOW PRESSURE UNIT LIS CONTROLLED IN RESPONSE TO A SPEED SIGNAL FROM THE HIGH PRESSURE UNIT WHICH IS USED AS THE SPEED REFERENCE FOR THE LOW PRESSURE UNIT WHICH IS USED CONTROL. AN ACCELERATION CATCH-UP BIAS SIGNAL IS SUPPLIED TO THE LOW PRESSURE ACCELERATION CONTROL FOR ACCELERATION THE LOW PRESSURE ACCELERATION CONTROL FOR ACCELERATING DIFFERENCE TO ABOUT ZERO. A PREEMERGENCY CONTROL FOR CHANNEL INSURES THAT THE TURBINE WILL BE SAFELY CONTROLLED WHEN APPROACHING AN OVERSPEED CONDITION.

Iterative guidance applied to generalized missions.

Abstract: Iterative guidance mode /IGM/ applied to effective gravity vector prediction, acceleration measurement of noise sensistivity and energy limitations

Acceleration of ultrarelativistic electrons in the Crab Nebula

Abstract: Ultrarelativistic electrons must be being accelerated in the Crab Nebula to maintain the synchrotron spectrum. Sufficient power to maintain the synchrotron spectrum is supplied by an observed damping of compressional motions in the central region of the nebula (the ‘wisps’ of Baade). An acceleration mechanism which involves compressional motions, the gyrorelaxation effect and the removal of pitch angle anisotropies by the generation of hydromagnetic waves is formulated and applied to a model of the Crab Nebula with acceleration confined to a central region. This can account for the power supplied to the electrons, the overall shape of the spectrum and allows acceleration up to energies corresponding to the synchrotron emission of hard X-rays. The acceleration process tends to flatten an initial energy spectrum.

DYNAMIC RESPONSE OF THE HEAD AND NECK OF THE LIVING HUMAN TO -Gx IMPACT ACCELERATION. 1. EXPERIMENTAL DESIGN AND PRELIMINARY EXPERIMENTAL DATA

Abstract: : A study is underway to determine the dynamic response of the head and neck of living human subjects to -Gx impact acceleration, using transducers to measure differential displacements and differential angular and linear accelerations of the head with reference to the base of the neck in response to the input acceleration measured at that point. A redundant photographic data system is being used for validation. Preliminary results are presented.

Method of measuring vibration characteristics of structures

Abstract: A testing device having a static mass equal to or less than the static mass of the structure to be tested in the local region of attachment, acting as a rigid mass at all frequencies, and having a measuring device portion which has a dynamic mass less than about ten times the least value of dynamic mass of the structure, is rigidly mounted on a test structure. The testing device is then vibrated and the resulting force which is applied to the test structure, the resulting acceleration of the test structure, and the phase angle between the force and acceleration are measured. The frequency of vibration is then varied and the above stated measurements are repeated. The testing device is then attached to a second point on the structure and the foregoing steps are repeated.

Attitude Determination Via Nonlinear Filtering

Abstract: The theory of nonlinear filtering has been applied to the problem of the attitude determination of a satellite. Two approximation methods have been studied with a view to practical implementation. Computer simulation results are included.

Statistical Analysis of Wide-Band Pseudorandom Matched Filter Sonars

Abstract: A stochastic model of pseudorandom (PR) signals is adopted and a statistical analysis carried out of the velocity (i. e., Doppler) and acceleration tolerances of wide-band PR matched filter sonar systems. The reference functions for these correlation detection systems are considered to be time-compressed or time-expanded replicas of the transmitted signal. Results are derived for the case of a PR signal having a flat power spectral density over a finite bandwidth. It is shown that the velocity and acceleration tolerances are essentially independent of the signal bandwidth and that therefore the radar-derived expressions for the narrow-band tolerances can be extended to the wide-band sonar case. An interesting result is that the derived acceleration tolerance is approximately three times the widely used estimate that is based on the target remaining in the same Doppler channel over the integration time.

Velocity sensing---comparison of field and laboratory methods

Abstract: THE EFFECT IS COMPARED OF VARYING THE SENSORY INPUT (VISUAL, AUDITORY, KINESTHETIC, TACTILE, AND VESTIBULAR CUES) ON THE APPRECIATION OF TRAVELED VELOCITY. A MOVIE TECHNIQUE WAS DEVELOPED TO REMOVE THE EFFECTS OF ACCELERATION AND TO PRESENT CONTROLLED FRONTAL AND PERIPHERAL VISUAL CUES. THE RANGE OF VELOCITIES WAS EXTENDED TO 100 MPH. IT IS CONCLUDED THAT (1) THE REMOVAL OF THE FORCE-SENSE FEEDBACK MECHANISM ACTS TO REDUCE THE RATIO OF THE ESTIMATED TO THE PRESENTED OR ACTUAL RANGE OF VELOCITIES; (2) THERE IS DIRECT VARIATION OF THE ABSOLUTE ERROR WITH VELOCITY AS THE RANGE IS EXTENDED TO INCLUDE HIGH SPEEDS; AND (3) SENSING OF VELOCITY BASED ON PERIPHERAL VISUAL STIMULATION APPEARS TO BE MORE RESISTANT TO EXPERIMENTAL ARTIFACTS, SUCH AS A MONOTONOUS ENVIRONMENT FATIGUE, AND THE BETA EFFECT (APPARENT MOVEMENT PRODUCED BY AN INCREASE OF ILLUMINATION OF PART OF THE FIELD), THAN FRONTAL VISUAL STIMULATION. A METHODOLOGICAL CONFUSION IN PLOTTING VELOCITY SENSING DATA WHEN USING THE METHODS OF ESTIMATION AND PRODUCTION IS POINTED OUT AS INFLUENCING THE DESCRIPTION OF SUCH DATA IN TERMS OF OVER-ESTIMATION AND UNDER-ESTIMATION. /AUTHOR/