147,227 research outputs found
Computer program for high pressure real gas effects
Computer program obtains the real-gas isentropic flow functions and thermodynamic properties of gases for which the equation of state is known. The program uses FORTRAN 4 subroutines which were designed for calculations of nitrogen and helium. These subroutines are easily modified for calculations of other gases
Coupled Mode Theory of Electron‐Beam Parametric Amplification
A theory of parametric amplification in a filamentary electron beam by transverse fields is developed in coupled mode form. Space charge effects are neglected. In addition to beam modes at the signal frequency, beam modes at frequencies ωn=ω+ω_p, n=0, ±1, ±2…, where ω_p is the pump frequency, are coupled together. A discussion of the general form of the equations is given and reveals the circumstances under which exponential gain or periodic energy transfer between various modes can occur. When applied to quadrupole electric pump fields, a description of the quadrupole amplifiers of Adler, Wade, and Gordon is obtained. This theory is then used to evaluate the noise contribution from synchronous beam modes and higher cyclotron idler modes. Coupling by axially symmetric electric fields and by axially symmetric magnetic fields is discussed, and other amplification schemes suggested. The theory of coupling by axially symmetric fields can also be used to study lens effects on noise in the gun region
Fractional Branes and the Entropy of 4D Black Holes
We reconsider the four dimensional extremal black hole constructed in type
IIB string theory as the bound state of D1-branes, D5-branes, momentum, and
Kaluza-Klein monopoles. Specifically, we examine the case of an arbitrary
number of monopoles. Consequently, the weak coupling calculation of the
microscopic entropy requires a study of the D1-D5 system on an ALE space. We
find that the complete expression for the Bekenstein-Hawking entropy is
obtained by taking into account the massless open strings stretched between the
fractional D-branes which arise in the orbifold limit of the ALE space. The
black hole sector therefore arises as a mixed Higgs-Coulomb branch of an
effective 1+1 dimensional gauge theory.Comment: 12 pages. 1 figure. v2: References adde
SPEEDY: An Eclipse-based IDE for invariant inference
SPEEDY is an Eclipse-based IDE for exploring techniques that assist users in
generating correct specifications, particularly including invariant inference
algorithms and tools. It integrates with several back-end tools that propose
invariants and will incorporate published algorithms for inferring object and
loop invariants. Though the architecture is language-neutral, current SPEEDY
targets C programs. Building and using SPEEDY has confirmed earlier experience
demonstrating the importance of showing and editing specifications in the IDEs
that developers customarily use, automating as much of the production and
checking of specifications as possible, and showing counterexample information
directly in the source code editing environment. As in previous work,
automation of specification checking is provided by back-end SMT solvers.
However, reducing the effort demanded of software developers using formal
methods also requires a GUI design that guides users in writing, reviewing, and
correcting specifications and automates specification inference.Comment: In Proceedings F-IDE 2014, arXiv:1404.578
Moisture-resistant coatings for optical components
Plasma polymerization technique is used to apply thin, adherent, hydrophobic coatings from chlorotrifluoroethylene monomer. Apparently much of the chlorine contained in original monomer is lost during polymerization, and characteristic C-Cl absorption in infrared region is essentially absent
Brazing process using'al-Si filler alloy reliably bonds aluminum parts
Brazing process employs an aluminum-silicon filler alloy for diffusion bonding of aluminum parts in a vacuum or inert gas atmosphere. This process is carried out at temperatures substantially below those required in conventional process and produces bonds of greater strength and reliability
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Dynamic error characteristics of touch trigger probes used with coordinate measuring machines
This paper discusses the dynamic error characteristics of touch trigger probes used with coordinate measuring machines. During the investigation, a number of important parameters have been identified, including measurement speed, probe longitude, approach distance, probe latitude, stylus length/stylus tip diameter, probe orientation, operating mode (scanning and nonscanning), scan pitch, preload spring force (gauging force), probe type, and the surface approach angle. This paper presents the detailed experimental design and the results obtained from the systematic experiments. These results have led to some useful recommendations for the reduction of the probe dynamic errors. Some of these recommendations included the selection of the optimum measurement speed, the setting of the preload spring force, and the choice of the probe type
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