Supersonic through-flow fan assessment

A study was conducted to assess the performance potential of a supersonic through-flow fan engine for supersonic cruise aircraft. It included a mean-line analysis of fans designed to operate with in-flow velocities ranging from subsonic to high supersonic speeds. The fan performance generated was used to estimate the performance of supersonic fan engines designed for four applications: a Mach 2.3 supersonic transport, a Mach 2.5 fighter, a Mach 3.5 cruise missile, and a Mach 5.0 cruise vehicle. For each application an engine was conceptualized, fan performance and engine performance calculated, weight estimates made, engine installed in a hypothetical vehicle, and mission analysis was conducted

STARLIB: A Next-Generation Reaction-Rate Library for Nuclear Astrophysics

STARLIB is a next-generation, all-purpose nuclear reaction-rate library. For the first time, this library provides the rate probability density at all temperature grid points for convenient implementation in models of stellar phenomena. The recommended rate and its associated uncertainties are also included. Currently, uncertainties are absent from all other rate libraries, and, although estimates have been attempted in previous evaluations and compilations, these are generally not based on rigorous statistical definitions. A common standard for deriving uncertainties is clearly warranted. STARLIB represents a first step in addressing this deficiency by providing a tabular, up-to-date database that supplies not only the rate and its uncertainty but also its distribution. Because a majority of rates are lognormally distributed, this allows the construction of rate probability densities from the columns of STARLIB. This structure is based on a recently suggested Monte Carlo method to calculate reaction rates, where uncertainties are rigorously defined. In STARLIB, experimental rates are supplemented with: (i) theoretical TALYS rates for reactions for which no experimental input is available, and (ii) laboratory and theoretical weak rates. STARLIB includes all types of reactions of astrophysical interest to Z = 83, such as (p,g), (p,a), (a,n), and corresponding reverse rates. Strong rates account for thermal target excitations. Here, we summarize our Monte Carlo formalism, introduce the library, compare methods of correcting rates for stellar environments, and discuss how to implement our library in Monte Carlo nucleosynthesis studies. We also present a method for accessing STARLIB on the Internet and outline updated Monte Carlo-based rates.Comment: Accepted for publication in the Astrophysical Journal Supplement Series; 96 pages, 22 figure

Determining the Future for Louisiana Sugar Cane Products, Inc.: A Case Study Analyzing Vertical Coordination Options

Deciding how to coordinate activities can be a challenge posed in any marketing chain. This case involves an agricultural cooperative that has focused entirely on marketing raw sugar cane for additional refinement. Recent dramatic shifts in the sector have caused the members of the cooperative to consider building a facility that will process the raw sugar cane. In so doing, the cooperative can consider using the spot market, using contracts, vertically coordinating, or vertically integrating. This case study of Louisiana Sugar Cane Products, Inc. is a unique, real-life case that can be widely used in marketing and cooperatives courses.Agribusiness, Crop Production/Industries,

Multi-frequency fine resolution imaging radar instrumentation and data acquisition

Development of a dual polarized L-band radar imaging system to be used in conjunction with the present dual polarized X-band radar is described. The technique used called for heterodyning the transmitted frequency from X-band to L-band and again heterodyning the received L-band signals back to X-band for amplification, detection, and recording

Thermal Equilibration of 26 Al

In astrophysical environments, the long-lived (t1/2 = 0.72 Myr) ground state of 26Al can communicate with its short-lived (t1/2 = 6.35 s) first excited state through thermal excitations. The result is that the astrophysical half-life for 26Al can be much shorter than the laboratory value, which can have an impact on the amount of 26Al produced at high temperatures. We have reexamined the equilibration process using the results of new calculations of some of the key transition rates. In addition, we discuss a simple way of describing the behavior of 26Al in a stellar plasma and use this to better define the conditions where equilibration is expected to be important. Finally, we present a series of network calculations to show how the interplay between the timescale for equilibration versus that for nuclear reactions will govern the evolution of 26Al

Direct measurement of the 14N(p,g)15O S-factor

We have measured the 14N(p,g)15O excitation function for energies in the range E_p = 155--524 keV. Fits of these data using R-matrix theory yield a value for the S-factor at zero energy of 1.64(17) keV b, which is significantly smaller than the result of a previous direct measurement. The corresponding reduction in the stellar reaction rate for 14N(p,g)15O has a number of interesting consequences, including an impact on estimates for the age of the Galaxy derived from globular clusters.Comment: 5 pages, 3 figures, submitted to Phys. Rev. Let

Constraining ^(26)Al+p resonances using ^(26)Al(^3He,d)^(27)Si

The ^(26)Al(^3He,d)^(27)Si reaction was measured from 0°≤θ_(c.m.)≤35° at E(^3He)=20 MeV using a quadrupole-dipole-dipole-dipole magnetic spectrometer. States in ^(27)Si were observed above the background at 7652 and 7741 keV and upper limits were set for the state at 7592 keV. Implications for the ^(26)Al(p,γ)^(27)Si stellar reaction rate are discussed

Experimental evidence of a natural parity state in 26^{26}Mg and its impact to the production of neutrons for the s process

We have studied natural parity states in $^{26}$Mg via the $^{22}$Ne($^{6}$Li,d)$^{26}$Mg reaction. Our method significantly improves the energy resolution of previous experiments and, as a result, we report the observation of a natural parity state in $^{26}$Mg. Possible spin-parity assignments are suggested on the basis of published $\gamma$-ray decay experiments. The stellar rate of the $^{22}$Ne($\alpha$,$\gamma$)$^{26}$Mg reaction is reduced and may give rise to an increase in the production of s-process neutrons via the $^{22}$Ne($\alpha$,n)$^{25}$Mg reaction.Comment: Published in PR