Normal injection of helium from swept struts into ducted supersonic flow

Recent design studies have shown that airframe-integrated scramjets should include instream mounted, swept-back strut fuel injectors to obtain short combustors. Because there was no data in the literature on mixing characteristics of swept strut fuel injectors, the present investigation was undertaken to provide such data. This investigation was made with two swept struts in a closed duct at Mach number of 4.4 and nominal jet-to-air mass flow ratio of 0.029 with helium used to simulate hydrogen fuel. The data is compared with flat plate mounted normal injector data to obtain the effect of swept struts on mixing. Three injector patterns were evaluated representing the range of hole spacing and jet-to-freestream dynamic pressure ratio of interest. Measured helium concentration, pitot pressure, and static pressure in the downstream mixing region are used to generate contour plots necessary to define the mixing region flow field and the mixing parameters

Design of a 240\u27 through span railroad bridge: Including analysis of stresses due to concentrated wheel loads, design of individual members, and drawings showing stresses, and details

The Span length will be 240\u27 center to center of end pins. Truss to be square ended, Track straight. Live load to consist of two engines, concentrating 289 tons over a length of 104\u27 followed by a uniform train of 2.1 tons per linear foot --Page 1

The Changing Nature of OA Journals: Helping Scholars Identify the Good, the Bad, and the Political

When the Open Access (OA) movement began at the beginning of the 21st century, librarians and select scholars saw it as a way to level the playing field by disseminating scholarly work freely, by easing the financial burden placed on rising subscription costs, and by offering alternatives to the traditional publishing model. Predatory and opportunistic OA publishers were quick to arrive on the scene, however, leaving faculty and researchers scrambling for a new and updated vetting process for selecting their publication targets. Jeffrey Beall’s blog and Beall’s List, along with other important publication directories, have become an important part of the effort to provide oversight and information to scholars about OA publishers. This paper will discuss OA controversies and review sources and opinions on the transformation of academic publishing efforts in the context of OA issues. Recent trends in librarianship demonstrate the need to educate authors on how to comprehensively research journals before submitting manuscripts to them, how to avoid predatory OA publishers, and where scholarly communication is going in terms of oversight and reputability of OA journals. This paper will briefly summarize many of the possible roles of the librarian, as well as discuss and evaluate the impact of Beall’s List on both the publishing world and librarianship

Nonreactive mixing study of a scramjet swept-strut fuel injector

The results are presented of a cold-mixing investigation performed to supply combustor design information and to determine optimum normal fuel-injector configurations for a general scramjet swept-strut fuel injector. The experimental investigation was made with two swept struts in a closed duct at a Mach number of 4.4 and a nominal ratio of jet mass flow to air mass flow of 0.0295, with helium used to simulate hydrogen fuel. Four injector patterns were evaluated; they represented the range of hole spacing and the ratio of jet dynamic pressure to free-stream dynamic pressure. Helium concentration, pitot pressure, and static pressure in the downstream mixing region were measured to generate the contour plots needed to define the mixing-region flow field and the mixing parameters. Experimental results show that the fuel penetration from the struts was less than the predicted values based on flat-plate data; but the mixing rate was faster and produced a mixing length less than one-half that predicted

ILRS Website Redesign

The International Laser Ranging Service (ILRS) website, http://ilrs.gsfc.nasa.gov, is the central source of information for all aspects of the service. The website provides information on the organization and operation of ILRS and descriptions of ILRS components, data, and products. Furthermore, the website and provides an entry point to the archive of these data and products available through the data centers. Links are provided to extensive information on the ILRS network stations including performance assessments and data quality evaluations. Descriptions of supported satellite missions (current, future, and past) are provided to aid in station acquisition and data analysis. The current format for the ILRS website has been in use since the early years of the service. Starting in 2010, the ILRS Central Bureau began efforts to redesign the look and feel for the website. The update will allow for a review of the contents, ensuring information is current and useful. This poster will detail the proposed design including specific examples of key sections and webpages

Relationships between various characterisations of wave tails

One can define several properties of wave equations that correspond to the absence of tails in their solutions, the most common one by far being Huygens' principle. Not all of these definitions are equivalent, although they are sometimes assumed to be. We analyse this issue in detail for linear scalar waves, establishing some relationships between the various properties. Huygens' principle is almost always equivalent to the characteristic propagation property, and in two spacetime dimensions the latter is equivalent to the zeroth order progressing wave propagation property. Higher order progressing waves in general do have tails, and do not seem to admit a simple physical characterisation, but they are nevertheless useful because of their close association with exactly solvable two-dimensional equations.Comment: Plain TeX, 26 page

Computation of p-Adic Heights and Log Convergence

This paper is about computational and theoretical questions regarding p-adic height pairings on elliptic curves over a global field K. The main stumbling block to computing them efficiently is in calculating, for each of the completions Kv at the places v of K dividing p, a single quantity: the value of the p-adic modular form E2 associated to the elliptic curve. Thanks to the work of Dwork, Katz, Kedlaya, Lauder and Monsky-Washnitzer we offer an efficient algorithm for computing these quantities, i.e., for computing the value of E2 of an elliptic curve. We also discuss the p-adic convergence rate of canonical expansions of the p-adic modular form E2 on the Hasse domain. In particular, we introduce a new notion of log convergence and prove that E2 is log convergent.Mathematic

Beam energy measurement at linear colliders using spin precession

Linear collider designs foresee some bends of about 5-10 mrad. The spin precession angle of one TeV electrons on 10 mrad bend is 23.2 rad and it changes proportional to the energy. Measurement of the spin direction using Compton scattering of laser light on electrons before and after the bend allows determining the beam energy with an accuracy about of 10^{-5}. In this paper the principle of the method, the procedure of the measurement and possible errors are discussed. Some remarks about importance of plasma focusing effects in the method of beam energy measurement using Moller scattering are given.Comment: 7 pages, Latex, 4 figures(.eps). In v.3 corresponds to journal publication. Talk at 26-th Advanced ICFA Beam Dynamic Workshop on Nanometre-Size Colliding Beams (Nanobeam2002), Lausanne, Switzerland, Sept 2-6, 200

TRUFAS, a wavelet based algorithm for the rapid detection of planetary transits

Aims: We describe a fast, robust and automatic detection algorithm, TRUFAS, and apply it to data that are being expected from the CoRoT mission. Methods: The procedure proposed for the detection of planetary transits in light curves works in two steps: 1) a continuous wavelet transformation of the detrended light curve with posterior selection of the optimum scale for transit detection, and 2) a period search in that selected wavelet transformation. The detrending of the light curves are based on Fourier filtering or a discrete wavelet transformation. TRUFAS requires the presence of at least 3 transit events in the data. Results: The proposed algorithm is shown to identify reliably and quickly the transits that had been included in a standard set of 999 light curves that simulate CoRoT data. Variations in the pre-processing of the light curves and in the selection of the scale of the wavelet transform have only little effect on TRUFAS' results. Conclusions: TRUFAS is a robust and quick transit detection algorithm, especially well suited for the analysis of very large volumes of data from space or ground-based experiments, with long enough durations for the target-planets to produce multiple transit events.Comment: 9 pages, 10 figures, accepted by A&

Direct observation of the multiple spin gap excitations in two-dimensional dimer system SrCu2(BO3)2

Various spin gap excitations have been observed in the two-dimensional dimer system SrCu_2(BO_3)_2 by means of submillimeter wave ESR. The zero-field energy gap of the lowest spin gap excitation shows a splitting into two triplet modes and the energy splitting clearly depends on the magnetic field orientation when a field is rotated in the {\mib {ac}}-plane. A zero-field splitting is also found between the S(_z)=+1 and S(_z)=-1 branches of each triplet. These behaviors are qualitatively explained by considering the anisotropic exchange coupling of inter-dimer and intra-dimer, respectively. The averaged value of the lowest spin gap energy is determined to be 722 \pm 2 GHz(34.7 K). We have also found the second spin gap excitation at 1140 GHz(54.7 K), which indicates that the inter-dimer coupling is significantly strong. Besides these modes, a number of gapped ESR absorption are found and we propose that these multiple magnetic excitations are caused by the localized nature of the excited state in the present system.Comment: 4pages 4figure