213,209 research outputs found

    Phase detector assembly Patent

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    Detector assembly for discriminating first signal with respect to presence or absence of second signal at time of occurrence of first signa

    Reaching DEEP in Math (Developing Educational Excellence and Proficiency in Mathematics)

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    This paper describes the DEEP in Math Program developed in the academic year 1998-1999 from a collaborative effort of the Louisiana Systemic lnitiative Program (LaSlP) and the Louisiana Department of Education (LDE). It includes evidence of impressive results in low achieving schools and in high-poverty districts targeted by the effort. The plan was for LaSlP to give intensive content and leadership training in Summer 1999 and academic year 1999-2000 to carefully selected. well-qualified math leaders. These leaders were then employed full-time in the 1999-2000 academic year and beyond by their local education authorities to work with all math teachers in a few designated schools at some cohesive subset of grades 3-8

    Lessons Learned from the Pioneers 10/11 for a Mission to Test the Pioneer Anomaly

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    Analysis of the radio-metric tracking data from the Pioneer 10/11 spacecraft at distances between 20--70 astronomical units (AU) from the Sun has consistently indicated the presence of an anomalous, small, constant Doppler frequency drift. The drift is a blue-shift, uniformly changing with rate a_t = (2.92 +/- 0.44) x 10^(-18) s/s^2. It can also be interpreted as a constant acceleration of a_P = (8.74 +/- 1.33) x 10^(-8) cm/s^2 directed towards the Sun. Although it is suspected that there is a systematic origin to the effect, none has been found. As a result, the nature of this anomaly has become of growing interest. Here we discuss the details of our recent investigation focusing on the effects both external to and internal to the spacecraft, as well as those due to modeling and computational techniques. We review some of the mechanisms proposed to explain the anomaly and show their inability to account for the observed behavior of the anomaly. We also present lessons learned from this investigation for a potential deep-space experiment that will reveal the origin of the discovered anomaly and also will characterize its properties with an accuracy of at least two orders of magnitude below the anomaly's size. A number of critical requirements and design considerations for such a mission are outlined and addressed.Comment: 11 pages, invited talk given at ``35th COSPAR Scientific Assebly,'' July 18-24, 2004, Paris, Franc

    On vv--domains and star operations

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    Let \ast be a star operation on an integral domain DD. Let \f(D) be the set of all nonzero finitely generated fractional ideals of DD. Call DD a \ast--Pr\"ufer (respectively, (,v)(\ast, v)--Pr\"ufer) domain if (FF1)=D(FF^{-1})^{\ast}=D (respectively, (FvF1)=D(F^vF^{-1})^{\ast}=D) for all F\in \f(D). We establish that \ast--Pr\"ufer domains (and (,v)(\ast, v)--Pr\"ufer domains) for various star operations \ast span a major portion of the known generalizations of Pr\"{u}fer domains inside the class of vv--domains. We also use Theorem 6.6 of the Larsen and McCarthy book [Multiplicative Theory of Ideals, Academic Press, New York--London, 1971], which gives several equivalent conditions for an integral domain to be a Pr\"ufer domain, as a model, and we show which statements of that theorem on Pr\"ufer domains can be generalized in a natural way and proved for \ast--Pr\"ufer domains, and which cannot be. We also show that in a \ast --Pr\"ufer domain, each pair of \ast -invertible \ast -ideals admits a GCD in the set of \ast -invertible \ast -ideals, obtaining a remarkable generalization of a property holding for the "classical" class of Pr\"ufer vv--multiplication domains. We also link DD being \ast --Pr\"ufer (or (,v)(\ast, v)--Pr\"ufer) with the group Inv(D)^{\ast}(D) of \ast -invertible \ast -ideals (under \ast-multiplication) being lattice-ordered

    Effects of equivalence ratio and dwell time on exhaust emissions from an experimental premixing prevaporizing burner

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    A flame-tube study was performed to determine the effects of equivalence ratio and residence time on exhaust emissions with premixed, prevaporized propane fuel. Nitrogen oxides emissions as low as .3 g NO2/kg fuel were measured with greater than 99% combustion efficiency at 800 K inlet temperature and an equivalence ratio of .4. For a constant combustion efficiency, lower nitrogen oxides emissions were obtained by burning very lean with relatively long residence times than by using somewhat higher equivalence ratios with shorter times

    The ground state and the long-time evolution in the CMC Einstein flow

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    Let (g,K)(k) be a CMC (vacuum) Einstein flow over a compact three-manifold M with non-positive Yamabe invariant (Y(M)). As noted by Fischer and Moncrief, the reduced volume V(k)=(-k/3)^{3}Vol_{g(k)}(M) is monotonically decreasing in the expanding direction and bounded below by V_{\inf}=(-1/6)Y(M))^{3/2}. Inspired by this fact we define the ground state of the manifold M as "the limit" of any sequence of CMC states {(g_{i},K_{i})} satisfying: i. k_{i}=-3, ii. V_{i} --> V_{inf}, iii. Q_{0}((g_{i},K_{i}))< L where Q_{0} is the Bel-Robinson energy and L is any arbitrary positive constant. We prove that (as a geometric state) the ground state is equivalent to the Thurston geometrization of M. Ground states classify naturally into three types. We provide examples for each class, including a new ground state (the Double Cusp) that we analyze in detail. Finally consider a long time and cosmologically normalized flow (\g,\K)(s)=((-k/3)^{2}g,(-k/3))K) where s=-ln(-k) is in [a,\infty). We prove that if E_{1}=E_{1}((\g,\K))< L (where E_{1}=Q_{0}+Q_{1}, is the sum of the zero and first order Bel-Robinson energies) the flow (\g,\K)(s) persistently geometrizes the three-manifold M and the geometrization is the ground state if V --> V_{inf}.Comment: 40 pages. This article is an improved version of the second part of the First Version of arXiv:0705.307
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