39,509 research outputs found
Control power requirements of VTOL aircraft Quarterly status report, 1 Apr. - 30 Jun. 1969
Computer derived reference design of intercity VTOL aircraft and analysis of control power requirements and operating cost
Wind energy system time-domain (WEST) analyzers
A portable analyzer which simulates in real time the complex nonlinear dynamics of horizontal axis wind energy systems was constructed. Math models for an aeroelastic rotor featuring nonlinear aerodynamic and inertial terms were implemented with high speed digital controllers and analog calculation. This model was combined with other math models of elastic supports, control systems, a power train and gimballed rotor kinematics. A stroboscopic display system graphically depicting distributed blade loads, motion, and other aerodynamic functions on a cathode ray tube is included. Limited correlation efforts showed good comparison between the results of this analyzer and other sophisticated digital simulations. The digital simulation results were successfully correlated with test data
Brown-Tail Moth, \u3ci\u3eEuproctis Chrysorrhoea,\u3c/i\u3e an Indigenous Pest of Parks and Public in the Benelux Countries (Lepidoptera: Lymantriidae)
Euproctis chrysorrhoea is a pest of park and shade trees and of the public in the Benelux countries as well as in the northeastern United States and Canada. In the Benelux countries the brown-tail moth is present every year in the dune regions, where it mainly feeds on Hippophae rhamnoides. Hairs from the larvae are irritating to the human skin producing a papular urticaria. An outbreak of the caterpillars produced widespread discomfort at a beach in the Netherlands in 1982 following defoliation of food plants and migration of the larvae seeking food, with resulting human contact, as well as wind dispersal of the hairs
Aerial Vehicle Tracking by Adaptive Fusion of Hyperspectral Likelihood Maps
Hyperspectral cameras can provide unique spectral signatures for consistently
distinguishing materials that can be used to solve surveillance tasks. In this
paper, we propose a novel real-time hyperspectral likelihood maps-aided
tracking method (HLT) inspired by an adaptive hyperspectral sensor. A moving
object tracking system generally consists of registration, object detection,
and tracking modules. We focus on the target detection part and remove the
necessity to build any offline classifiers and tune a large amount of
hyperparameters, instead learning a generative target model in an online manner
for hyperspectral channels ranging from visible to infrared wavelengths. The
key idea is that, our adaptive fusion method can combine likelihood maps from
multiple bands of hyperspectral imagery into one single more distinctive
representation increasing the margin between mean value of foreground and
background pixels in the fused map. Experimental results show that the HLT not
only outperforms all established fusion methods but is on par with the current
state-of-the-art hyperspectral target tracking frameworks.Comment: Accepted at the International Conference on Computer Vision and
Pattern Recognition Workshops, 201
Contracts, grants and funding summary of supersonic cruise research and variable-cycle engine technology programs, 1972 - 1982
NASA-SCAR (AST) program was initiated in 1972 at the direct request of the Executive Office of the White House and Congress following termination of the U.S. SST program. The purpose of SCR was to conduct a focused research and technology program on those technology programs which contributed to the SST termination and, also, to provide an expanded data base for future civil and military supersonic transport aircraft. Funding for the Supersonic Cruise Research (SCR) Program was initiated in fiscal year 1973 and terminated in fiscal year 1981. The program was implemented through contracts and grants with industry, universities, and by in-house investigations at the NASA/OAST centers. The studies included system studies and five disciplines: propulsion, stratospheric emissions impact, materials and structures, aerodynamic performance, and stability and control. The NASA/Lewis Variable-Cycle Engine (VCE) Component Program was initiated in 1976 to augment the SCR program in the area of propulsion. After about 2 years, the title was changed to VCE Technology program. The total number of contractors and grantees on record at the AST office in 1982 was 101 for SCR and 4 for VCE. This paper presents a compilation of all the contracts and grants as well as the funding summaries for both programs
3D Velocity and Density Reconstructions of the Local Universe with Cosmicflows-1
This paper presents an analysis of the local peculiar velocity field based on
the Wiener Filter reconstruction method. We used our currently available
catalog of distance measurements containing 1,797 galaxies within 3000 km/s:
Cosmicflows-1. The Wiener Filter method is used to recover the full 3D peculiar
velocity field from the observed map of radial velocities and to recover the
underlying linear density field. The velocity field within a data zone of 3000
km/s is decomposed into a local component that is generated within the data
zone and a tidal one that is generated by the mass distribution outside that
zone. The tidal component is characterized by a coherent flow toward the
Norma-Hydra-Centaurus (Great Attractor) region while the local component is
dominated by a flow toward the Virgo Cluster and away from the Local Void. A
detailed analysis shows that the local flow is predominantly governed by the
Local Void and the Virgo Cluster plays a lesser role. The analysis procedure
was tested against a mock catalog. It is demonstrated that the Wiener Filter
accurately recovers the input velocity field of the mock catalog on the scale
of the extraction of distances and reasonably recovers the velocity field on
significantly larger scales. The Bayesian Wiener Filter reconstruction is
carried out within the ?CDM WMAP5 framework. The Wiener Filter reconstruction
draws particular attention to the importance of voids in proximity to our
neighborhood. The prominent structure of the Local Supercluster is wrapped in a
horseshoe collar of under density with the Local Void as a major component.Comment: Accepted for ApJ, August 6, 201
- …