1,655 research outputs found
Method and system for monitoring and displaying engine performance parameters
The invention is believed a major improvement that will have a broad application in governmental and commercial aviation. It provides a dynamic method and system for monitoring and simultaneously displaying in easily scanned form the available, predicted, and actual thrust of a jet aircraft engine under actual operating conditions. The available and predicted thrusts are based on the performance of a functional model of the aircraft engine under the same operating conditions. Other critical performance parameters of the aircraft engine and functional model are generated and compared, the differences in value being simultaneously displayed in conjunction with the displayed thrust values. Thus, the displayed information permits the pilot to make power adjustments directly while keeping him aware of total performance at a glance of a single display panel
Quasirandomness in hypergraphs
An -vertex graph of edge density is considered to be quasirandom
if it shares several important properties with the random graph . A
well-known theorem of Chung, Graham and Wilson states that many such `typical'
properties are asymptotically equivalent and, thus, a graph possessing one
such property automatically satisfies the others.
In recent years, work in this area has focused on uncovering more quasirandom
graph properties and on extending the known results to other discrete
structures. In the context of hypergraphs, however, one may consider several
different notions of quasirandomness. A complete description of these notions
has been provided recently by Towsner, who proved several central equivalences
using an analytic framework. We give short and purely combinatorial proofs of
the main equivalences in Towsner's result.Comment: 19 page
Simulator evaluation of displays for a revised takeoff performance monitoring system
Cockpit displays for a Takeoff Performance Monitoring System (TOPMS) to provide pilots with graphic and alphanumeric information pertinent to their decision to continue or abort a takeoff are evaluated. Revised head-down and newly developed head-up displays were implemented on electronic screens in the real-time Transport Systems Research Vehicle (TSRV) Simulator for the Boeing 737 airplane at the Langley Research Center and evaluated by 17 NASA, U.S. Air Force, airline, and industry pilots. Both types of displays were in color, but they were not dependent upon it. The TOPMS head-down display is composed of a runway graphic overlaid with symbolic status and advisory information related to both the expected takeoff point and the predicted stop point (in the event an abort becomes necessary). In addition, an overall Situation Advisory Flag indicates a preferred course of action based on analysis of the various elements of airplane performance and system status. A simpler head-up display conveys most of this same information and relates it to the visual scene. The evaluation pilots found the displays to be credible, easy to monitor, and appropriate for the task. In particular, the pilots said the head-up display was monitored with very little effort and did not obstruct or distract them from monitoring the simulated out-the-window runway scene. This report augments NASA TP-2908, 1989
The HLA-E Gene encodes two differentially regulated Transcripts and a Cell Surface Protein
An HLA-E-specific oligonucleotide probe was used
to study the expressioonf HLA-E. This probed etects
two HLA-E transcripts, 1.8 and 2.7 kb in size, which
are present in varying ratios in allt issues and cell
lines investigated. We demonstrate that alternative
poly(A) site usage accounts for the differential regulation
of the two HLA-E mRNA species. Sequence
analysis of three cDNA clones, representing the two
transcripts of HLA-E, and of anH LA-E gene encoded
by cosmid cd3.14, revealed identity of gene and
cDNA in the 3’ untranslated region. S1 nuclease
protection assays confirmed that the two HLA-E
transcripts are not alternative splicing products.
Introduction of cd3.14, together with human ,&m
into the murine myeloma cell line P3X63-Ag8.653,
resulted in a cell surface expresosf ioan HLA-class
I heavy chain detectablbey indirect immunofluorescence
whereas transfection into the humBaznr n expressing
mouse L cell line, 527 was negative with
regard to cell surface expressionC. ell surface labeling
of transfectants and immunoprecipitation with
a monomorphic HLA class I-specific antibodyo r an
antibody against human &m confirmed the presence
of an HLA-E H chain on the cell surface. These
results indicate that the HLA-E gene codes for a
class I H chain that can be expressed on the cell
surface
Geostatistical analysis of an experimental stratigraphy
[1] A high-resolution stratigraphic image of a flume-generated deposit was scaled up to sedimentary basin dimensions where a natural log hydraulic conductivity (ln( K)) was assigned to each pixel on the basis of gray scale and conductivity end-members. The synthetic ln( K) map has mean, variance, and frequency distributions that are comparable to a natural alluvial fan deposit. A geostatistical analysis was conducted on selected regions of this map containing fluvial, fluvial/ floodplain, shoreline, turbidite, and deepwater sedimentary facies. Experimental ln(K) variograms were computed along the major and minor statistical axes and horizontal and vertical coordinate axes. Exponential and power law variogram models were fit to obtain an integral scale and Hausdorff measure, respectively. We conclude that the shape of the experimental variogram depends on the problem size in relation to the size of the local-scale heterogeneity. At a given problem scale, multilevel correlation structure is a result of constructing variogram with data pairs of mixed facies types. In multiscale sedimentary systems, stationary correlation structure may occur at separate scales, each corresponding to a particular hierarchy; the integral scale fitted thus becomes dependent on the problem size. The Hausdorff measure obtained has a range comparable to natural geological deposits. It increases from nonstratified to stratified deposits with an approximate cutoff of 0.15. It also increases as the number of facies incorporated in a problem increases. This implies that fractal characteristic of sedimentary rocks is both depositional process - dependent and problem-scale-dependent
Flight investigation of a vertical-velocity command system for VTOL aircraft
A flight investigation was undertaken to assess the potential benefits afforded by a vertical-velocity command system (VVCS) for VTOL (vertical take-off and landing) aircraft. This augmentation system was conceived primarily as a means of lowering pilot workload during decelerating approaches to a hover and/or landing under category III instrument meteorological conditions. The scope of the investigation included a determination of acceptable system parameters, a visual flight evaluation, and an instrument flight evaluation which employed a 10 deg, decelerating, simulated instrument approach task. The results indicated that the VVCS, which decouples the pitch and vertical degrees of freedom, provides more accurate glide-path tracking and a lower pilot workload than does the unaugmented system
A piloted-simulation evaluation of two electronic display formats for approach and landing
The results of a piloted-simulation evaluation of the benefits of adding runway symbology and track information to a baseline electronic-attitude-director-indicator (EADI) format for the approach-to-landing task were presented. The evaluation was conducted for the baseline format and for the baseline format with the added symbology during 3 deg straight-in approaches with calm, cross-wind, and turbulence conditions. Flight-path performance data and pilot subjective comments were examined with regard to the pilot's tracking performance and mental workload for both display formats. The results show that the addition of a perspective runway image and relative track information to a basic situation-information EADI format improve the tracking performance both laterally and vertically during an approach-to-landing task and that the mental workload required to assess the approach situation was thus reduced as a result of integration of information
Method and system for monitoring and displaying engine performance parameters
The invention is a method and system for monitoring and directly displaying the actual thrust produced by a jet aircraft engine under determined operating conditions and the available thrust and predicted (commanded) thrust of a functional model of an ideal engine under the same determined operating conditions. A first set of actual value output signals representative of a plurality of actual performance parameters of the engine under the determined operating conditions is generated and compared with a second set of predicted value output signals representative of the predicted value of corresponding performance parameters of a functional model of the engine under the determined operating conditions to produce a third set of difference value output signals within a range of normal, caution, or warning limit values. A thrust indicator displays when any one of the actual value output signals is in the warning range while shaping function means shape each of the respective difference output signals as each approaches the limit of the respective normal, caution, and warning range limits
Airplane takeoff and landing performance monitoring system
The invention is a real-time takeoff and landing performance monitoring system for an aircraft which provides a pilot with graphic and metric information to assist in decisions related to achieving rotation speed (V.sub.R) within the safe zone of a runway, or stopping the aircraft on the runway after landing or take-off abort. The system processes information in two segments: a pretakeoff segment and a real-time segment. One-time inputs of ambient conditions and airplane configuration information are used in the pretakeoff segment to generate scheduled performance data. The real-time segment uses the scheduled performance data, runway length data and transducer measured parameters to monitor the performance of the airplane throughout the takeoff roll. Airplane acceleration and engine-performance anomalies are detected and annunciated. A novel and important feature of this segment is that it updates the estimated runway rolling friction coefficient. Airplane performance predictions also reflect changes in head wind occurring as the takeoff roll progresses. The system provides a head-down display and a head-up display. The head-up display is projected onto a partially reflective transparent surface through which the pilot views the runway. By comparing the present performance of the airplane with a continually predicted nominal performance based upon given conditions, performance deficiencies are detected by the system and conveyed to pilot in form of both elemental information and integrated information
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