6,623 research outputs found

    An implicit semianalytic numerical method for the solution of nonequilibrium chemistry problems

    Get PDF
    The first order differential equation form systems of equations. They are solved by a simple and relatively accurate implicit semianalytic technique which is derived from a quadrature solution of the governing equation. This method is mathematically simpler than most implicit methods and has the exponential nature of the problem embedded in the solution

    Correlations for determining thermodynamic properties of hydrogen-helium gas mixtures at temperatures from 7,000 to 35,000 K

    Get PDF
    Simple relations for determining the enthalpy and temperature of hydrogen-helium gas mixtures were developed for hydrogen volumetric compositions from 1.0 to 0.7. These relations are expressed as a function of pressure and density and are valid for a range of temperatures from 7,000 to 35,000 K and pressures from 0.10 to 3.14 MPa. The proportionality constant and exponents in the correlation equations were determined for each gas composition by applying a linear least squares curve fit to a large number of thermodynamic calculations obtained from a detailed computer code. Although these simple relations yielded thermodynamic properties suitable for many engineering applications, their accuracy was improved significantly by evaluating the proportionality constants at postshock conditions and correlating these values as a function of the gas composition and the product of freestream velocity and shock angle. The resulting equations for the proportionality constants in terms of velocity and gas composition and the corresponding simple realtions for enthalpy and temperature were incorporated into a flow field computational scheme. Comparison was good between the thermodynamic properties determined from these relations and those obtained by using a detailed computer code to determine the properties. Thus, an appreciable savings in computer time was realized with no significant loss in accuracy

    Millisecond accuracy video display using OpenGL under Linux

    Get PDF
    To measure people’s reaction times to the nearest millisecond, it is necessary to know exactly when a stimulus is displayed. This article describes how to display stimuli with millisecond accuracy on a normal CRT monitor, using a PC running Linux. A simple C program is presented to illustrate how this may be done within X Windows using the OpenGL rendering system. A test of this system is reported that demonstrates that stimuli may be consistently displayed with millisecond accuracy. An algorithm is presented that allows the exact time of stimulus presentation to be deduced, even if there are relatively large errors in measuring the display time

    Temporal Localization of Fine-Grained Actions in Videos by Domain Transfer from Web Images

    Full text link
    We address the problem of fine-grained action localization from temporally untrimmed web videos. We assume that only weak video-level annotations are available for training. The goal is to use these weak labels to identify temporal segments corresponding to the actions, and learn models that generalize to unconstrained web videos. We find that web images queried by action names serve as well-localized highlights for many actions, but are noisily labeled. To solve this problem, we propose a simple yet effective method that takes weak video labels and noisy image labels as input, and generates localized action frames as output. This is achieved by cross-domain transfer between video frames and web images, using pre-trained deep convolutional neural networks. We then use the localized action frames to train action recognition models with long short-term memory networks. We collect a fine-grained sports action data set FGA-240 of more than 130,000 YouTube videos. It has 240 fine-grained actions under 85 sports activities. Convincing results are shown on the FGA-240 data set, as well as the THUMOS 2014 localization data set with untrimmed training videos.Comment: Camera ready version for ACM Multimedia 201

    Study of the technique of stellar occultation

    Get PDF
    The results are reported of a study of the stellar occultation technique for measuring the composition of the atmosphere. The intensity of starlight was monitored during the occultation using the Wisconsin stellar ultraviolet photometers aboard the Orbiting Astronomical Observatory (OAO-A2). A schematic diagram of an occultation is shown where the change in intensity at a given wavelength is illustrated. The vertical projection of the attenuation region is typically 60 km deep for molecular oxygen and 30 km deep for ozone. Intensity profiles obtained during various occultations were analyzed by first determining the tangential columm density of the absorbing gases, and then Abel inverting the column densities to obtain the number density profile. Errors are associated with each step in the inversion scheme and have been considered as an integral part of this study

    The provenance of tills overlying the eastern part of the South Mountain Batholith, Nova Scotia

    Get PDF
    Happing of quarternary deposits on the South Mountain Batholitb (SMB) has resulted in a four-fold subdivision of tills, divided primarily on the basis of clast lithology, texture, stratigraphic position and morphology. Three tills have clast lithologies characterized by granites eroded from the South Mountain Batholih. The oldest granite till is a compact till of restricted distribution, mianly observed In drumlin cores. Two younger granite tills dominate the surficial deposits of portions of the SMB and have textural properties ascribed to melt-out tills. The fourth till represents a farther-travelled till with a variable clast provenance typified by pebbles derived from both the SMB and regions to the north. Clast dispersal evidence suggests that all tills were transported in a general southward direction. Detailed clast examinations allow reliable conclusions concerning direction of Ice flow and lithologic relationship between till and bedrock of the SMB. The SMB is an area of multiple glaciatlon where till prospecting cannot be successful unless the direction of till transport and source areas are established. RÉSUMÉ Dn levé cartographique des dépôts quaternaires recouvrant le Batholite de South Mountain à permis de mettre en évidence quatre varlétés de tills en fonctlon de la lithologie des clastes, la texture, la position stratlgraphlque et la morphologic Dana trola tills, les clastes nontrent des lithologles caractérisées par des granites arrachés au Batholite de South Mountain (BSM). Le plus vleux till de granite est un till tasse. de faible étendue, observe surtout dans les noyaux de drumlins. Dans certaines portions du BSM, les dépôts de surface sont dominés par deux tills de granite plus recents qui possedent des caractéristlques texturales rapportées aux tills d'ablation. Le quatriéme till a parcouru une plus grande distance; la source de ses clastes est variable et comprend typiquement des galets provenant tant du BSM que des régions plus au nord. La dispersion des blocaux suggère un direction générale de transport des tills vers le sud. Un exanen approfondi des clastes permet de tirer de solides conclusions à propos de la direction de l’écouleroent glacialre et de la relation lithologique entre le till et le socle du BSM. Le BSM a subi de multiples glaciatlons et la prospection du till n'y est done guère profitable à molns de déterminer la direction de transport et la source du till. [Traduit par le journal

    Connectionist Temporal Modeling for Weakly Supervised Action Labeling

    Full text link
    We propose a weakly-supervised framework for action labeling in video, where only the order of occurring actions is required during training time. The key challenge is that the per-frame alignments between the input (video) and label (action) sequences are unknown during training. We address this by introducing the Extended Connectionist Temporal Classification (ECTC) framework to efficiently evaluate all possible alignments via dynamic programming and explicitly enforce their consistency with frame-to-frame visual similarities. This protects the model from distractions of visually inconsistent or degenerated alignments without the need of temporal supervision. We further extend our framework to the semi-supervised case when a few frames are sparsely annotated in a video. With less than 1% of labeled frames per video, our method is able to outperform existing semi-supervised approaches and achieve comparable performance to that of fully supervised approaches.Comment: To appear in ECCV 201

    The Vitamin A and the Vitamin E Content of Field-Cured and Artificially Cured Alfalfa Hay

    Get PDF
    A comparative study of the vitamin A content of field-cured and artificially cured alfalfa was made by comparing the growth produced by 124 rats receiving alfalfa hay as their source of vitamin A. From the results of this study, in which the experiments were duplicated, it is concluded that under the conditions of these experiments the artificially cured alfalfa was twice as potent in vitamin A as was the field-cured alfalfa. The comparative study of the vitamin E content of these hays was made by comparing the number of litters produced by groups of female rats which received graded quantities of either field-cured or artificially cured alfalfa as their source of vitamin E. It is concluded that the artificial drying of the alfalfa tended to preserve its vitamin E content to a greater degree than did field curing

    Synthesis And Characterization Of (pyNO−)2GaCl: A Redox-Active Gallium Complex

    Get PDF
    We report the synthesis of a gallium complex incorporating redox-active pyridyl nitroxide ligands. The (pyNO−)2GaCl complex was prepared in 85% yield via a salt metathesis route and was characterized by 1H and 13C NMR spectroscopies, X-ray diffraction, and theory. UV–Vis absorption spectroscopy and electrochemistry were used to access the optical and electrochemical properties of the complex, respectively. Our discussion focuses primarily on a comparison of the gallium complex to the corresponding aluminum derivative and shows that although the complexes are very similar, small differences in the electronic structure of the complexes can be correlated to the identity of the metal

    Inferring Species Trees Directly from Biallelic Genetic Markers: Bypassing Gene Trees in a Full Coalescent Analysis

    Get PDF
    The multi-species coalescent provides an elegant theoretical framework for estimating species trees and species demographics from genetic markers. Practical applications of the multi-species coalescent model are, however, limited by the need to integrate or sample over all gene trees possible for each genetic marker. Here we describe a polynomial-time algorithm that computes the likelihood of a species tree directly from the markers under a finite-sites model of mutation, effectively integrating over all possible gene trees. The method applies to independent (unlinked) biallelic markers such as well-spaced single nucleotide polymorphisms (SNPs), and we have implemented it in SNAPP, a Markov chain Monte-Carlo sampler for inferring species trees, divergence dates, and population sizes. We report results from simulation experiments and from an analysis of 1997 amplified fragment length polymorphism (AFLP) loci in 69 individuals sampled from six species of {\em Ourisia} (New Zealand native foxglove)
    • …
    corecore