26,947 research outputs found
Integrated command, control, communications and computation system functional architecture
The functional architecture for an integrated command, control, communications, and computation system applicable to the command and control portion of the NASA End-to-End Data. System is described including the downlink data processing and analysis functions required to support the uplink processes. The functional architecture is composed of four elements: (1) the functional hierarchy which provides the decomposition and allocation of the command and control functions to the system elements; (2) the key system features which summarize the major system capabilities; (3) the operational activity threads which illustrate the interrelationahip between the system elements; and (4) the interfaces which illustrate those elements that originate or generate data and those elements that use the data. The interfaces also provide a description of the data and the data utilization and access techniques
Non-Volatile Magnonic Logic Circuits Engineering
We propose a concept of magnetic logic circuits engineering, which takes an
advantage of magnetization as a computational state variable and exploits spin
waves for information transmission. The circuits consist of magneto-electric
cells connected via spin wave buses. We present the result of numerical
modeling showing the magneto-electric cell switching as a function of the
amplitude as well as the phase of the spin wave. The phase-dependent switching
makes it possible to engineer logic gates by exploiting spin wave buses as
passive logic elements providing a certain phase-shift to the propagating spin
waves. We present a library of logic gates consisting of magneto-electric cells
and spin wave buses providing 0 or p phase shifts. The utilization of phases in
addition to amplitudes is a powerful tool which let us construct logic circuits
with a fewer number of elements than required for CMOS technology. As an
example, we present the design of the magnonic Full Adder Circuit comprising
only 5 magneto-electric cells. The proposed concept may provide a route to more
functional wave-based logic circuitry with capabilities far beyond the limits
of the traditional transistor-based approach
Hysteresis loops of magnetic thin films with perpendicular anisotropy
We model the magnetization of quasi two-dimensional systems with easy
perpendicular (z-)axis anisotropy upon change of external magnetic field along
z. The model is derived from the Landau-Lifshitz-Gilbert equation for
magnetization evolution, written in closed form in terms of the z component of
the magnetization only. The model includes--in addition to the external
field--magnetic exchange, dipolar interactions and structural disorder. The
phase diagram in the disorder/interaction strength plane is presented, and the
different qualitative regimes are analyzed. The results compare very well with
observed experimental hysteresis loops and spatial magnetization patterns, as
for instance for the case of Co-Pt multilayers.Comment: 8 pages, 8 figure
Low-speed stability and control wind-tunnel investigations of effects of spanwise blowing on fighter flight characteristics at high angles of attack
The effects of spanwise blowing on two configurations representative of current fighter airplanes were investigated. The two configurations differed only in wing planform, with one incorporating a trapezoidal wing and the other a 60 delta wing. Emphasis was on determining the lateral-directional characteristics, particularly in the stall/departure angle-of-attack range; however, the effects of spanwise blowing on the longitudinal aerodynamics were also determined. The-tunnel tests included measurement of static force and forced-oscillation aerodynamic data, visualization of the airflow changes created by the spanwise blowing, and free-flight model tests. The effects of blowing rate, chordwise location of the blowing ports, asymmetric blowing, and blowing on the conventional aerodynamic control characteristics were investigated. In the angle-of-attack regions in which the spanwise blowing substantially improved the wing upper-surface flow field (i.e., provided reattachment of the flow aft of the leading-edge vortex), improvements in both static and dynamic lateral-directional stability were observed. Blowing effects on stability could be proverse or adverse depending on blowing rate, blowing port loaction, and wing planform. Free-flight model tests of the trapezoidal wing confirmed the beneficial effects of spanwise blowing measured in the static and dynamic force tests
Control-system techniques for improved departure/spin resistance for fighter aircraft
Some fundamental information on control system effects on controllability of highly maneuverable aircraft at high angles of attack are summarized as well as techniques for enhancing fighter aircraft departure/spin resistance using control system design. The discussion includes: (1) a brief review of pertinent high angle of attack phenomena including aerodynamics, inertia coupling, and kinematic coupling; (2) effects of conventional stability augmentation systems at high angles of attack; (3) high angle of attack control system concepts designed to enhance departure/spin resistance; and (4) the outlook for applications of these concepts to future fighters, particularly those designs which incorporate relaxed static stability
EOS image data processing system definition study
The Image Processing System (IPS) requirements and configuration are defined for NASA-sponsored advanced technology Earth Observatory System (EOS). The scope included investigation and definition of IPS operational, functional, and product requirements considering overall system constraints and interfaces (sensor, etc.) The scope also included investigation of the technical feasibility and definition of a point design reflecting system requirements. The design phase required a survey of present and projected technology related to general and special-purpose processors, high-density digital tape recorders, and image recorders
Using the LANDSAT data collection system for field geophysics: Operations in the British Virgin Islands
This particular application was to vertical geodesy by tide gauge and tiltmeter on a small desert island in the British Virgin Islands. The performance of the LANDSAT system under potentially marginal circumstances was found to be excellent
Control of dissipation in superconducting films by magnetic stray fields
Hybrid superconducting/magnetic nanostructures on Si substrates have been
built with identical physical dimensions but different magnetic configurations.
By constructing arrays based on Co-dots with in-plane, out-of-plane, and vortex
state magnetic configurations, the stray fields are systematically tuned.
Dissipation in the mixed state of superconductors can be decreased (increased)
by several orders of magnitude by decreasing (increasing) the stray magnetic
fields. Furthermore, ordering of the stray fields over the entire array helps
to suppress dissipation and enhance commensurability effects increasing the
number of dissipation minima.Comment: 16 pages including 4 figures; accepted in Applied Physics Letter
Management of Casualty Birds of Prey
Increasingly, practitioners are presented with injured raptors, either found as wild birds or kept as trained falcons. Orthopedic injuries are the most common result of trauma to birds of prey. While many of the principles of mammalian medicine and surgery can be applied to avian species, raptors present special problems of management, restraint and handling, diagnosis, anesthesia, fracture healing and repair, and rehabilitation
Dissociation of Hemoglobin into Subunits II. HUMAN OXYHEMOGLOBIN: GEL FILTRATION STUDIES
Abstract The dissociation of normal human oxyhemoglobin has been studied by gel filtration under conditions of neutral pH and moderate ionic strength, with the use of both integral boundaries, formed between solution and solvent, and finite difference boundaries, formed between solution and solution. The experimental data obtained have been treated by nonlinear least squares procedures to estimate the relevant parameters with their associated standard errors. For this purpose, theoretical equations have been derived for two models, firstly a simple dimer-tetramer reversible equilibrium, and secondly a monomer-dimer-trimer-tetramer reversible equilibrium. In both models the dependence on concentration of the elution volume of the individual species has been taken into account
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