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At least 613 records · Page 34

Michelson interferometer with separated inputs and outputs, double pass, and compensation

A novel configuration is proposed for a Michelson interferometer spectrometer, which will be insensitive to tilts or displacements, and which employs separated inputs and outputs and double passing for higher resolution. The great advantage of such a compensated design is a relaxation of mechanical tolerances, which is especially beneficial for instruments in hostile environments. The Atmospheric Trace Molecule Spectroscopy project, which must work reliably after being subjected to the vibrations of a Space Shuttle launch, would benefit from the use of such an instrument.

Mather, J. C.↗

Rotary Drive Mechanism Accepts Two Inputs

Mechanism connects two drives to single output shaft without clutches or planetary gears. More reliable than clutch-based two-drive mechanism and less bulky than planetary mechanism. Moreover, designed for any ratio of output to input speed, including an 1:1 ratio, unlike planetary gears. Drives operate simultaneously or separately.

Webster, Larry D.↗

Dual motion valve with single motion input

A dual motion valve includes two dual motion valve assemblies with a rotary input which allows the benefits of applying both rotary and axial motion to a rotary sealing element with a plurality of ports. The motion of the rotary sealing element during actuation provides axial engagement of the rotary sealing element with a stationary valve plate which also has ports. Fluid passages are created through the valve when the ports of the rotary sealing element are aligned with the ports of the stationary valve plate. Alignment is achieved through rotation of the rotary sealing element with respect to the stationary valve plate. The fluid passages provide direct paths which minimize fluid turbulence created in the fluid as it passes through the valve.

Belew, Robert↗

Chandrasekhar equations for infinite dimensional systems. Part 2: Unbounded input and output case

A set of equations known as Chandrasekhar equations arising in the linear quadratic optimal control problem is considered. In this paper, we consider the linear time-invariant system defined in Hilbert spaces involving unbounded input and output operators. For a general class of such systems, the Chandrasekhar equations are derived and the existence, uniqueness, and regularity of the results of their solutions established.

Ito, Kazufumi↗

Acousto-ultrasonic input-output characterization of unidirectional fiber composite plate by SH waves

A unidirectional fiberglass epoxy composite plate specimen is modelled as a homogeneous transversely isotropic continuum plate medium. Acousto-ultrasonic non-contact input-output characterization by tracing SH waves in the continuum is studied theoretically with a transmitting and receiving transducer located on the same face of the plate. It is found that the directional dependence of the phase velocity of the SH waves travelling in the transversely isotropic medium has a significant effect on the delay time as opposed to the phase velocity of the SH wave travelling in an isotropic medium.

Williams, James H., Jr.↗

"Thumball" Auxiliary Data-Input Device

Track-ball-type device mounted on joystick and operated by thumb. Thumball designed to enable precise input of data about two different axes to autopilot, avionics computer, or other electronic device without need for operator to remove hands from joystick or other vehicle control levers.

Garner, H. Douglas↗

Modal survey of the space shuttle solid rocket motor using multiple input methods

The ability to accurately characterize propellant in a finite element model is a concern of engineers tasked with studying the dynamic response of the Space Shuttle Solid Rocket Motor (SRM). THe uncertainties arising from propellant characterization through specimem testing led to the decision to perform a model survey and model correlation of a single segment of the Shuttle SRM. Multiple input methods were used to excite and define case/propellant modes of both an inert segment and, later, a live propellant segment. These tests were successful at defining highly damped, flexible modes, several pairs of which occured with frequency spacing of less than two percent.

Brillhart, Ralph↗

Acousto-ultrasonic input-output characterization of unidirectional fiber composite plate by SV waves

A unidirectional fiberglass epoxy compostie specimen is modelled as a homogeneous transversely isotropic continuum plate medium. Acousto-ultrasonic noncontact input-output characterization is studied theoretically with a transmitting and a receiving transducer located on the same face of the plate. The single reflection problem for an incident SV wave at a plane boundary in transversely isotropic medium is analyzed. An obliquely incident SV wave results in a reflected SV wave and a reflected P wave for an angle of incidence of the incident SV wave less than the critical angle. Otherwise, there exists only an SV wave in the medium as the reflected P wave degenerates into a surface wave travelling parallel to the plane boundary. The amplitude ratio of the reflected SV wave is -1 when the angle of incidence is greater than or = the critical angle. The directional dependence of the phase velocity of the SV wave propagating in the transversely isotropic medium has a significant effect on the delay time, as opposed to the directional independence of the phase velocity of a shear wave propagating in an isotropic medium. The displacements associated with the SV wave in the plate and which may be detected by the noncontact receiving transducer are approximated by an asymptotic solution for an infinite transversely isotropic medium subjected to a harmonic point load.

Liao, Peter↗

Input-output-controlled nonlinear equation solvers

To upgrade the efficiency and stability of the successive substitution (SS) and Newton-Raphson (NR) schemes, the concept of input-output-controlled solvers (IOCS) is introduced. By employing the formal properties of the constrained version of the SS and NR schemes, the IOCS algorithm can handle indefiniteness of the system Jacobian, can maintain iterate monotonicity, and provide for separate control of load incrementation and iterate excursions, as well as having other features. To illustrate the algorithmic properties, the results for several benchmark examples are presented. These define the associated numerical efficiency and stability of the IOCS.

Padovan, Joseph↗

Simulator comparison of thumball, thumb switch, and touch screen input concepts for interaction with a large screen cockpit display format

A piloted simulation study was conducted comparing three different input methods for interfacing to a large screen, multiwindow, whole flight deck display for management of transport aircraft systems. The thumball concept utilized a miniature trackball embedded in a conventional side arm controller. The multifunction control throttle and stick (MCTAS) concept employed a thumb switch located in the throttle handle. The touch screen concept provided data entry through a capacitive touch screen installed on the display surface. The objective and subjective results obtained indicate that, with present implementations, the thumball concept was the most appropriate for interfacing with aircraft systems/subsystems presented on a large screen display. Not unexpectedly, the completion time differences between the three concepts varied with the task being performed, although the thumball implementation consistently outperformed the other two concepts. However, pilot suggestions for improved implementations of the MCTAS and touch screen concepts could reduce some of these differences.

Jones, Denise R.↗

Dynamic test input generation for multiple-fault isolation

Recent work is Causal Reasoning has provided practical techniques for multiple fault diagnosis. These techniques provide a hypothesis/measurement diagnosis cycle. Using probabilistic methods, they choose the best measurements to make, then update fault hypotheses in response. For many applications such as computers and spacecraft, few measurement points may be accessible, or values may change quickly as the system under diagnosis operates. In these cases, a hypothesis/measurement cycle is insufficient. A technique is presented for a hypothesis/test-input/measurement diagnosis cycle. In contrast to generating tests a priori for determining device functionality, it dynamically generates tests in response to current knowledge about fault probabilities. It is shown how the mathematics previously used for measurement specification can be applied to the test input generation process. An example from an efficient implementation called Multi-Purpose Causal (MPC) is presented.

Schaefer, Phil↗

Input-output characterization of fiber reinforced composites by P waves

Input-output characterization of fiber composites is studied theoretically by tracing P waves in the media. A new path motion to aid in the tracing of P and the reflection generated SV wave paths in the continuum plate is developed. A theoretical output voltage from the receiving transducer is calculated for a tone burst. The study enhances the quantitative and qualitative understanding of the nondestructive evaluation of fiber composites which can be modeled as transversely isotropic media.

Renneisen, John D.↗

On the sensitivity of a residual circulation model to differences in input temperature data

The residual mean circulation (RMC) formulation of zonally averaged transport in the middle atmosphere produces a circulation which depends on the distributions of net diabatic heating and temperature. Such circulations are from two temperature data sets, using the same radiative transfer code (Rosenfield et al. 1987). These circulations are then used to transport N2O in a photochemical model. The circulations and the resulting N2O distributions are notably different during the Northern Hemisphere winter, with that based on the NMC temperatures producing too much upward transport in the tropical stratosphere, as judged by comparison with the stratospheric and mesoscale sounder data. The experiment demonstrates that model calculations, in general, and perturbation assessments, in particular, are likely to be quite sensitive to the choice of input temperature data (where this is not computed self-consistently). It also reveals what appears to be a seasonally dependent bias in NMC zonally averaged temperatures with respect to those obtained from the LIMS instrument during 1978/1979.

Guthrie, Paul D.↗

Space market model space industry input-output model

The goal of the Space Market Model (SMM) is to develop an information resource for the space industry. The SMM is intended to contain information appropriate for decision making in the space industry. The objectives of the SMM are to: (1) assemble information related to the development of the space business; (2) construct an adequate description of the emerging space market; (3) disseminate the information on the space market to forecasts and planners in government agencies and private corporations; and (4) provide timely analyses and forecasts of critical elements of the space market. An Input-Output model of market activity is proposed which are capable of transforming raw data into useful information for decision makers and policy makers dealing with the space sector.

Hodgin, Robert F.↗

The program on radiative inputs of the sun to the Earth (rise)

General concerns about changes in the Earth's climate and in the ozone layer have increased the importance of measuring and understanding variations in the sun's radiative outputs. These outputs appear, for instance, at the top of the list of global change forcing agents in the recent FY-90 document on the U.S. Global Change Program. Significant advances have been made over the past decade in radiometry of the total solar irradiance. Photometry of light variations in stars similar to the sun, but much younger, is providing new insights into the sun's variations in luminosity and UV radiation at previous epochs of interest to paleoclimate studies. Measurement of the sun's 11-year output variability in the ultraviolet and extreme ultraviolet still possess a challenge of great importance. All of these topics are addressed by the program on Radiative Inputs of the Sun to Earth (RISE). RISE is a 5-year program of observations, data analysis, and theory, that has been defined at two workshops held in Boulder, Colorado in November 1987, and in Tucson, Arizona in October 1989. These meetings involved about 60 solar and atmospheric physicists, and stellar astronomers. A proceedings of the 1987 workshop was issued in early 1988. A substantial component of the program, consisting of ground-based observations, data analysis, and theory, is directed at the National Science Foundation (NSF) and the program is seeking a FY-92 funding start at the NSF. RISE also makes recommendations on measurements required from NASA and NOAA satellites.

Foukal, Peter V.↗

Development and testing of controller performance evaluation methodology for multi-input/multi-output digital control systems

Described here is the development and implementation of on-line, near real time controller performance evaluation (CPE) methods capability. Briefly discussed are the structure of data flow, the signal processing methods used to process the data, and the software developed to generate the transfer functions. This methodology is generic in nature and can be used in any type of multi-input/multi-output (MIMO) digital controller application, including digital flight control systems, digitally controlled spacecraft structures, and actively controlled wind tunnel models. Results of applying the CPE methodology to evaluate (in near real time) MIMO digital flutter suppression systems being tested on the Rockwell Active Flexible Wing (AFW) wind tunnel model are presented to demonstrate the CPE capability.

Pototzky, Anthony↗

Suggestions for CAP-TSD mesh and time-step input parameters

Suggestions for some of the input parameters used in the CAP-TSD (Computational Aeroelasticity Program-Transonic Small Disturbance) computer code are presented. These parameters include those associated with the mesh design and time step. The guidelines are based principally on experience with a one-dimensional model problem used to study wave propagation in the vertical direction.

Bland, Samuel R.↗