Preliminary Tests on the Vaporization of Fuel Sprays

High-speed motion pictures were taken of fuel sprays injected into the combustion chamber of the N.A.C.A. combustion apparatus. Three fuels, ethyl alcohol, gasoline, and fuel oil, which differed considerably in volatility were tested. By maintaining the engine temperature below that required for ignition the spray could be studied from soon after the start of injection until 130 crank degrees later. The results show that the sprays vaporize appreciably so that it is possible for the ignition in high speed compression-ignition engines to take place from the vapor phase

Effect of High Air Velocities on the Distribution and Penetration of a Fuel Spray

By means of the NACA Spray Photography Equipment high speed moving pictures were taken of the formation and development of fuel sprays from an automatic injection valve. The sprays were injected normal to and counter to air at velocities from 0 to 800 feet per second. The air was at atmosphere temperature and pressure. The results show that high air velocities are an effective means of mixing the fuel spray with the air during injection

Observing the polar oceans with spaceborne radar

The application of spaceborne imaging radar data to polar oceanography and sea ice is explored. Several problems come to mind which are presently ripe with ideas and models, but are in need of new data, SAR data, for any progress to be made. These are the study of the ice mass balance, the ice momentum balance, and the circulation of the Arctic Ocean. These problems are described along with the data which is applicable to them and can be extracted from SAR imagery. Some uses are discussed of these data to explore mesoscale processes which affect the oceans and ice cover

Characterizing bean pod rot in Arkansas and Missouri

Green beans are an important crop grown for processing in both Arkansas and Missouri. Green beans are harvested mechanically using non-selective picking fingers. Harvested beans are then transported in bulk to processing plants that are located at various locations throughout the midSouth. Thus, the crop is managed for high quality, avoiding pod blemishes caused by insects and diseases. One of the consistent quality problems that affect Arkansas and Missouri green bean crops is pod rot. Two of the causal agents of pod rot that have been reported by researchers and vegetable companies alike are Pythium aphanidermatum and an unidentified Phytophthora sp. In this study, 15 growers’ fields were selected and soil samples (at planting), pod samples (at harvest), and environmental data were taken from each field. Disease incidence for field sites ranged from 0 to 7.3%. Pathogens associated with pod rot were Sclerotinia sclerotiorum, Rhizoctonia solani, a Phytophthora sp., and Pythium spp. The two suspected causal agents for pod rot, Pythium and Phytophthora spp., were found in all but one of the 12 field sites assessed for pod rot. Pythium inoculum potential, as determined by a baiting technique, was not a good indicator of pod rot incidence. In addition, soil temperature and water were not associated with pod rot. Pods collected at harvest having symptoms of pod rot were either in direct contact with the soil, senescing leaf tissue, or other diseased pods

Science, technology, and the national posture note no. 1

Dependence of national science and technological progress on research and developmen

The N.A.C.A. Apparatus for Studying the Formation and Combustion of Fuel Sprays and the Results from Preliminary Tests

Described here is an apparatus for studying the formation and combustion of fuel sprays under conditions closely simulating those in a high speed compression-ignition engine. The apparatus consists of a single-cylinder modified test engine, a fuel injection system so designed that a single charge of fuel can be injected into the combustion chamber, an electric driving motor, and a high-speed photographic apparatus. The cylinder head of the engine has a vertical disk form of combustion chamber whose sides are glass windows. When the fuel is injected into the combustion chamber, motion pictures at the rate of 2000 per second are taken of the spray formation by means of spark discharges. When combustion takes place, the light of combustion is recorded on the same photographic film as the spray photographs. Included here are the results of some tests to determine the effect of air temperature, air flow, and nozzle design on the spray formation. The results show that the compression temperature has little effect on the penetration of the fuel spray, but does not affect the dispersion, that air velocities of about 300 feet per second are necessary to destroy the core of the spray, and that the effect of air flow on the spray is controlled to a certain extent by the design of the injection nozzle. The results on the combustion of the spray show that when ignition does not take place until after spray cut-off, the ignition may start almost simultaneously throughout the combustion chamber or at different points throughout the chamber. When ignition takes place before spray cut-off, the combustion starts around the edge of the spray and then spreads throughout the chamber

Experimental determination of unsteady blade element aerodynamics in cascades. Volume 2: Translation mode cascade

A two dimensional cascade of harmonically oscillating airfoils was designed to model a near tip section from a rotor which was known to have experienced supersonic translational model flutter. This five bladed cascade had a solidity of 1.52 and a setting angle of 0.90 rad. Unique graphite epoxy airfoils were fabricated to achieve the realistic high reduced frequency level of 0.15. The cascade was tested over a range of static pressure ratios approximating the blade element operating conditions of the rotor along a constant speed line which penetrated the flutter boundary. The time steady and time unsteady flow field surrounding the center cascade airfoil were investigated

Economic Evaluation of Soybean Fungicide Seed Treatments

The effect of nine different fungicide seed treatments for soybeans were tested from 2004 to 2007 at Keiser, Stuttgart, and Hope, Arkansas. While seedling emergence was effective across all treatments, only three treatments showed statistically significant differences in partial returns, defined as gross revenue minus seed and seed treatment costs. Comparisons of the regret a producer would experience as a result of non-optimal seed treatment suggested that broad spectrum seed treatment could enhance profitability by an average of $32 per acre with similar treatment recommendations across a range of seeding rates, output prices and study conditions.Crop Production/Industries, Production Economics,

Generative probabilistic models of neuron morphology

Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2013.Cataloged from PDF version of thesis.Includes bibliographical references (page 40).Thanks to automation in ultrathin sectioning and confocal and electron microscopy, it is now possible to image large populations of neurons at single-cell resolution. This imaging capability promises to create a new field of neural circuit microanatomy. Three goals of such a field would be to trace multi-cell neural networks, to classify neurons into morphological cell types, and to compare patterns and statistics of connectivity in large networks to meaningful null models. However, those goals raise significant computational challenges. In particular, since neural morphology spans six orders of magnitude in length (roughly 1 nm-1 mm), a spatial hierarchy of representations is needed to capture micron-scale morphological features in nanometer resolution images. For this thesis, I have built and characterized a system that learns such a representation as a Multivariate Hidden Markov Model over skeletonized neurons. I have developed and implemented a maximum likelihood method for learning an HMM over a directed, unrooted tree structure of arbitrary degree. In addition, I have developed and implemented a set of object-oriented data structures to support this HMM, and to produce a directed tree given a division of the leaf nodes into inputs and outputs. Furthermore, I have developed a set of features on which to train the HMM based only on information in the skeletonized neuron, and I have tested this system on a dataset consisting of confocal microscope images of 14 fluorescence-labeled mouse retinal ganglion cells. Additionally, I have developed a system to simulate neurons of varying difficulty for the HMM, and analyzed its performance on those neurons. Finally, I have explored whether the HMMs this system learns could successfully detect errors in simulated and, eventually, neural datasets.by Stephen Rothrock Serene.M. Eng