Data simulation for the Lightning Imaging Sensor (LIS)

This project aims to build a data analysis system that will utilize existing video tape scenes of lightning as viewed from space. The resultant data will be used for the design and development of the Lightning Imaging Sensor (LIS) software and algorithm analysis. The desire for statistically significant metrics implies that a large data set needs to be analyzed. Before 1990 the quality and quantity of video was insufficient to build a usable data set. At this point in time, there is usable data from missions STS-34, STS-32, STS-31, STS-41, STS-37, and STS-39. During the summer of 1990, a manual analysis system was developed to demonstrate that the video analysis is feasible and to identify techniques to deduce information that was not directly available. Because the closed circuit television system used on the space shuttle was intended for documentary TV, the current value of the camera focal length and pointing orientation, which are needed for photoanalysis, are not included in the system data. A large effort was needed to discover ancillary data sources as well as develop indirect methods to estimate the necessary parameters. Any data system coping with full motion video faces an enormous bottleneck produced by the large data production rate and the need to move and store the digitized images. The manual system bypassed the video digitizing bottleneck by using a genlock to superimpose pixel coordinates on full motion video. Because the data set had to be obtained point by point by a human operating a computer mouse, the data output rate was small. The loan and subsequent acquisition of a Abekas digital frame store with a real time digitizer moved the bottleneck from data acquisition to a problem of data transfer and storage. The semi-automated analysis procedure was developed using existing equipment and is described. A fully automated system is described in the hope that the components may come on the market at reasonable prices in the next few years

Lightning observations from space shuttle

The experimental program of the Earth Sciences and Applications Division at NASA/MSFC includes development of the Lightning Imaging Sensor (LIS) for the NOAA Earth Observing System (EOS) Polar Platform. The research plan is to use existing lightning information to generate simulated data for the LIS experiment. Navigation algorithms were used to transform pixel locations to latitude and longitude values. The simulated data would then be used to test and develop algorithms for the analysis of LIS data. Individual frames of video imagery obtained from Space Shuttle Missions provide the raw data for the simulation. Individual video frames were digitized to get the pixel locations of lightning flashes. The pixel locations will be used to locate the geographical position of the event. Because of a lack of detailed knowledge of camera orientation with respect to the Space Shuttle, video scenes that contain identifiable city lights were chosen for analysis. A method for locating the payload bay camera axis was developed and tested. Two measurements are needed: the pixel location of the apparent horizon and a timed siting of a known location passing the principal line of the image. Individual video frames were navigated and lightning illuminated clouds were located on the map. Satisfactory agreement in location was achieved for cities and LLP lightning locations. Ground truth measurements were compared to satellite observations. A vertical lightning event was identified on the horizon. Very low frequency (VLF) transmission on this particular occassion shows a strong response to negative cloud to cloud flashes

Standard operating procedures for sweetpotato breeding data management. COP Breeding Data Management SweetGAINS

Current modernization efforts of sweetpotato breeding operations in Africa establish a new mindset. A modern sweetpotato breeding program continuously generates vast amounts of data on which it depends for all decision making throughout the program. Without a proper systematization of efforts, it is likely that significant mistakes can be unwillingly made, which would impact in a negative manner both genetic gains and the adoption of new varieties by smallholders. This document describes standard operating procedures (SOPs) for implementing breeding data workflows to ensure that all necessary breeding data are recorded appropriately and made easily accessible. This document needs to be considered as an alive one, as through its ensuing iterations additional SOPs will be added, and the current ones would be modified to reflect the learnings acquired. The data management SOPs in this volume cover the following key sweetpotato breeding data workflows: phenotyping, crossing, quality assessment, germplasm management, and DNA sample management. A relational database, SPBase (www.sweetpotatobase.org)1, plays a central role as a breeding data management system across workflows. Several other digital tools have been developed to connect to SPBase to facilitate recording and uploading different types of data

The extraordinary Hall effect in coherent epitaxial tau (Mn,Ni)Al thin films on GaAs

Ultrathin coherent epitaxial films of ferromagnetic tau(Mn,Ni)0.60Al0.40 have been grown by molecular beam epitaxy on GaAs substrates. X-ray scattering and cross-sectional transmission electron microscopy measurements confirm that the c axis of the tetragonal tau unit cell is aligned normal to the (001) GaAs substrate. Measurements of the extraordinary Hall effect (EHE) show that the films are perpendicularly magnetized, exhibiting EHE resistivities saturating in the range of 3.3-7.1 muOMEGA-cm at room temperature. These values of EHE resistivity correspond to signals as large as +7 and -7 mV for the two magnetic states of the film with a measurement current of 1 mA. Switching between the two magnetic states is found to occur at distinct field values that depend on the previously applied maximum field. These observations suggest that the films are magnetically uniform. As such, tau(Mn,Ni)Al films may be an excellent medium for high-density storage of binary information

Non-Volatile Memory Characteristics of Submicrometre Hall Structures Fabricated in Epitaxial Ferromagnetic MnAl Films on GaAs

Hall-effect structures with submicrometre linewidths (<0.3pm) have been fabricated in ferromagnetic thin films of Mn[sub 0.60]Al[sub 0.40] which are epitaxially grown on a GaAs substrate. The MnAl thin films exhibit a perpendicular remanent magnetisation and an extraordinary Hall effect with square hysteretic behaviour. The presence of two distinct stable readout states demonstrates the potential of using ultrasmall ferromagnetic volumes for electrically addressable, nonvolatile storage of digital information

Simultaneous OH-PLIF and schlieren imaging of flame acceleration in an obstacle-laden channel

Flame acceleration in stoichiometric H_2/O_2 at 12 and 25 kPa initial pressure in an obstacle-laden square cross-section channel was studied experimentally using planar laser-induced fluorescence imaging of hydroxyl radicals (OH-PLIF) and simultaneous high-speed schlieren imaging. Results were obtained resolving the explosion front structure as it develops immediately after ignition as a slow-flame to the eventual formation of a shock-flame complex in the fast-flame regime. The images provide a novel level of detail and allow for the determination of the effects of turbulence-flame and shock-flame interaction. In the slow-flame regime, vortex shedding off obstacle edges occurs over long time-scales, vortices are convected downstream and turbulent combustion takes place in the obstacle wakes. The fast-flame regime is marked by the presence of compression waves (and shock waves) which interact with the flame and cause macroscopic deformation of the flame and small-scale wrinkling due to Richtmyer-Meshkov instability. A quasi-steady fast-flame is characterized by the close proximity of the precursor shock and the turbulent flame. The flow-field that governs the flame shape is established impulsively by the precursor shock. Shock-flame interactions lead to flame front perturbations on both small and large scales. The OH-PLIF technique makes it possible to discern the flame front from other density interfaces that appear in the complex fast-flame structure observed in schlieren images and also eliminates the line-of-sight integration limitation

Hot surface ignition dynamics in premixed hydrogen–air near the lean flammability limit

The dynamics of ignition of premixed hydrogen–air from a hot glow plug were investigated in a combined experimental and numerical study. Surface temperatures during heating and at ignition were obtained from 2-color pyrometry, gas temperatures were measured by high-speed Mach–Zehnder interferometry, and far-field effects were captured by high-speed schlieren imaging. Numerical simulations considered detailed chemical kinetics and differential diffusion effects. In addition to the known cyclic (puffing) combustion phenomenon, singular ignition events (single puff) were observed near the lean flammability limit. Detailed analysis of the results of our numerical simulations reveal the existence of multiple combustion transients within the thermal boundary layer following the initial ignition event and, at late times, sustained chemical reaction within a thermal plume above the glow plug. The results have significant implications for ignition from hot surfaces within near-flammability limit mixtures, at the edge of plumes resulting from accidental release of hydrogen, or within the containments of nuclear power plants during severe accidents

Flame propagation across an obstacle: OH-PLIF and 2-D simulations with detailed chemistry

Flame propagation across a single obstacle inside a closed square channel is studied experimentally and numerically using a stoichiometric H_2/O_2 mixture at initial conditions 15 kPa and 300 K. The 50% blockage obstacle consists of a pair of fence-type obstacles mounted on the top and bottom walls of the channel. Direct optical visualization was performed using single-image measurement of the planar laser-induced fluorescence of the OH radical (OH-PLIF) and simultaneous high-speed schlieren video to study the flame topology and the flame tip velocity along the channel streamwise axis, respectively. The OH-PLIF images provide a novel level of detail and permit a thorough evaluation of the simulation accuracy. The flame tip accelerates to a peak velocity of 590 m/s just downstream of the obstacle followed by a deceleration and subsequent re-acceleration. The unburnt gas flow ahead of the flame is subsonic at all times. The flame does not show any signs of diffusive-thermal instability. Vortex–flame interactions in the recirculation zones downstream of the obstacle wrinkle the flame. The numerical simulations, based on solving the 2-D compressible reactive Navier–Stokes equations with detailed chemistry, predict the flame tip velocity accurately. However, differences in flame topology are observed, specifically, wrinkling is over-estimated. The over-prediction of flame wrinkling suggests a lower dissipation rate in the numerical simulations than in reality, which could be a consequence of neglecting the third channel dimension. Conditional means of the fuel consumption rate are similar to the consumption rates of 1-D unstretched laminar flames at all times. The increase in pressure during flame propagation causes an increase in fuel consumption rate which needs to be accounted for in simplified modeling approaches