9,068 research outputs found
Infrared video tracking of UAVs: Guided landing in the absence of GPS signals
Master's Project (M.S.) University of Alaska Fairbanks, 2019Unmanned Aerial Vehicles (UAVs) use Global Positioning System (GPS) signals to
determine their position for automated flight. The GPS signals require an unobstructed view
of the sky in order to obtain position information. When inside without a clear view of the
sky, such as in a building or mine, other methods are necessary to obtain the relative position
of the UAV. For obstacle avoidance a LIDAR/SONAR system is sufficient to ensure
automated flight, but for precision landing the LIDAR/SONAR system is insufficient for
effectively identifying the location of the landing platform and providing flight control inputs
to guide the UAV to the landing platform. This project was developed in order to solve this
problem by creating a guidance system utilizing an infrared (IR) camera to track an IR LED
and blue LEDs mounted on the UAV from a RaspberryPI 3 Model B+. The RaspberryPI,
using OpenCV libraries, can effectively track the position of the LED lights mounted on the
UAV, determine rotational and lateral corrections based on this tracking, and, using
Dronekit-Python libraries, command the UAV to position itself and land on the platform of
the Husky UGV (Unmanned Ground Vehicle)
Basic design considerations for a small scientific satellite
Scientific satellite design considerations for spacecraft itself, spacecraft/launch vehicle interface, and ground support equipment and transportatio
Pre-design study for a modern four-bladed rotor for the Rotor System Research Aircraft (RSRA)
Various candidate rotor systems were compared in an effort to select a modern four-bladed rotor for the RSRA. The YAH-64 rotor system was chosen as the candidate rotor system for further development for the RSRA. The process used to select the rotor system, studies conducted to mate the rotor with the RSRA and provide parametric variability, and the development plan which would be used to implement these studies are presented. Drawings are included
Creep of plasma sprayed zirconia
Specimens of plasma-sprayed zirconia thermal barrier coatings with three different porosities and different initial particle sizes were deformed in compression at initial loads of 1000, 2000, and 3500 psi and temperatures of 1100 C, 1250 C, and 1400 C. The coatings were stabilized with lime, magnesia, and two different concentrations of yttria. Creep began as soon as the load was applied and continued at a constantly decreasing rate until the load was removed. Temperature and stabilization had a pronounced effect on creep rate. The creep rate for 20% Y2O3-80% ZrO2 was 1/3 to 1/2 that of 8% Y2O3-92% ZrO2. Both magnesia and calcia stabilized ZrO2 crept at a rate 5 to 10 times that of the 20% Y2O3 material. A near proportionality between creep rate and applied stress was observed. The rate controlling process appeared to be thermally activated, with an activation energy of approximately 100 cal/gm mole K. Creep deformation was due to cracking and particle sliding
Method of preparing zinc orthotitanate pigment
Zinc orthotitanate suitable for use as a pigment for spacecraft thermal control coatings is prepared by heating a slightly zinc deficient reaction mixture of precipitated oxalates of zinc and titanium. The reaction mixture can be formed by coprecipitation of zinc and titanium oxalates from chloride solution or by mixing separately precipitated oxalates. The mixture is first heated to 400 to 600 C to remove volatiles and is then rapidly heated at 900 to 1200 C. Zinc orthotitanate produced by this method exhibits the very fine particle size needed for thermal control coatings as well as stability in a space environment
The Subcolonization and Buildup of \u3ci\u3eTetrastichus Julis,\u3c/i\u3e (Hymenoptera: Eulophidae) a Larval Parasitoid of the Cereal Leaf Beetle, (Coleoptera: Chrysomelidae) in the Lower Peninsula of Michigan
Following initial establishment of the parasitoid, Tetrastichus julis (Walker), at a carefully managed field nursery, releases of parasitized Oulema melanopus larvae were made by Michigan county agents at preselected sites throughout the lower peninsula during 1970-74. A follow-up recovery program during 1971-75 revealed continued dispersion and population increase for T. julis. An independent census verified the increasing rates of parasitism
Two-channel Kondo physics in tunnel-coupled double quantum dots
We investigate theoretically the possibility of observing two-channel Kondo
(2CK) physics in tunnel-coupled double quantum dots (TCDQDs), at both zero and
finite magnetic fields; taking the two-impurity Anderson model (2AIM) as the
basic TCDQD model, together with effective low-energy models arising from it by
Schrieffer-Wolff transformations to second and third order in the tunnel
couplings. The models are studied primarily using Wilson's numerical
renormalization group. At zero-field our basic conclusion is that while 2CK
physics arises in principle provided the system is sufficiently
strongly-correlated, the temperature window over which it could be observed is
much lower than is experimentally feasible. This finding disagrees with recent
work on the problem, and we explain why. At finite field, we show that the
quantum phase transition known to arise at zero-field in the two-impurity Kondo
model (2IKM), with an essentially 2CK quantum critical point, persists at
finite fields. This raises the prospect of access to 2CK physics by tuning a
magnetic field, although preliminary investigation suggests this to be even
less feasible than at zero field.Comment: 10 pages, 8 figures. Version as published in PR
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