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Three-Dimensional Computed Tomography as a Method for Finding Die Attach Voids in Diodes
NASA analyzes electrical, electronic, and electromechanical (EEE) parts used in space vehicles to understand failure modes of these components. The diode is an EEE part critical to NASA missions that can fail due to excessive voiding in the die attach. Metallography, one established method for studying the die attach, is a time-intensive, destructive, and equivocal process whereby mechanical grinding of the diodes is performed to reveal voiding in the die attach. Problems such as die attach pull-out tend to complicate results and can lead to erroneous conclusions. The objective of this study is to determine if three-dimensional computed tomography (3DCT), a nondestructive technique, is a viable alternative to metallography for detecting die attach voiding. The die attach voiding in two- dimensional planes created from 3DCT scans was compared to several physical cross sections of the same diode to determine if the 3DCT scan accurately recreates die attach volumetric variabilit
Heavy Baryon Masses in Large N_c HQET
We argue that in the large N_c HQET, the masses of the s-wave low-spin heavy
baryons equal to the heavy quark mass plus proton mass approximately. To the
subleading order, the heavy baryon mass 1/N_c expansion not only has the same
form, but also has the same coefficients as that of the light baryon. Based on
this, numerical analysis is made.Comment: 7 pages, latex, no figures, to appear in Phys. Lett.
Precision stellar radial velocity measurements with FIDEOS at the ESO 1-m telescope of La Silla
We present results from the commissioning and early science programs of
FIDEOS, the new high-resolution echelle spectrograph developed at the Centre of
Astro Engineering of Pontificia Universidad Catolica de Chile, and recently
installed at the ESO 1m telescope of La Silla. The instrument provides spectral
resolution R = 43,000 in the visible spectral range 420-800 nm, reaching a
limiting magnitude of 11 in V band. Precision in the measurement of radial
velocity is guaranteed by light feeding with an octagonal optical fibre,
suitable mechanical isolation, thermal stabilisation, and simultaneous
wavelength calibration. Currently the instrument reaches radial velocity
stability of = 8 m/s over several consecutive nights of observation
R-Parity Violation at HERA
We summarize the signals at HERA in supersymmetric models with explicitly
broken R-parity. As the most promising case, we consider in detail the resonant
production of single squarks through an operator , a
production process analogous to that for leptoquarks. However, the dominant
decay of the squark to a quark and a photino leads to a very different
experimental signature. We examine in particular the case where the photino
decays to a positron and two quarks. Using a detailed Monte-Carlo procedure we
obtain a discovery limit in the squark mass---Yukawa coupling plane. HERA can
discover a squark for a mass as large as 270 \gev and for an R-parity
violating Yukawa coupling as small as .Comment: 23 pages, 11 figures upon request, Oxford Preprint, OUNP-92-1
The Mass-Radius Relationship for Very Low Mass Stars: Four New Discoveries from the HATSouth Survey
We report the discovery of four transiting F-M binary systems with companions
between 0.1-0.2 Msun in mass by the HATSouth survey. These systems have been
characterised via a global analysis of the HATSouth discovery data, combined
with high-resolution radial velocities and accurate transit photometry
observations. We determined the masses and radii of the component stars using a
combination of two methods: isochrone fitting of spectroscopic primary star
parameters, and equating spectroscopic primary star rotation velocity with
spin-orbit synchronisation. These new very low mass companions are HATS550-016B
(0.110 -0.006/+0.005 Msun, 0.147 -0.004/+0.003 Rsun), HATS551-019B (0.17
-0.01/+0.01 Msun, 0.18 -0.01/+0.01 Rsun), HATS551-021B (0.132 -0.005/+0.014
Msun, 0.154 -0.008/+0.006 Rsun), HATS553-001B (0.20 -0.02/+0.01 Msun, 0.22
-0.01/+0.01 Rsun). We examine our sample in the context of the radius anomaly
for fully-convective low mass stars. Combining our sample with the 13 other
well-studied very low mass stars, we find a tentative 5% systematic deviation
between the measured radii and theoretical isochrone models.Comment: 17 pages, 8 figures, accepted for publication in MNRA
Fermion Scattering off CP-Violating Electroweak Bubble Wall
A general prescription to solve the Dirac equation in the presence of
CP-violating electroweak bubble wall is presented. The profile of the bubble
wall is not specified except that the wall height is and zero deep in the
broken- and the symmetric-phase regions, respectively, where is a fermion
mass given by the Higgs-vacuum-expectation value and the Yukawa coupling. The
CP-violating effects are evaluated by regarding CP-violating part of the bubble
wall as a perturbation to CP-conserving solutions. The basic quantity,
, which would contribute to the
cosmological baryon asymmetry, is estimated for some typical profiles of the
wall, where () is the reflection
coefficient of right-handed chiral fermion (anti-fermion).Comment: 30 pages, 2 figures ( uuencoded tar.Z file of PS files is appended ),
plain TeX with phyzzx, tables and epsf,SAGA-HE-55--KYUSHU-HET-1
Success Factors of Small and Medium-Sized International Enterprises in the Chinese Market from the Perspective of Polish Direct Investment (Cultural Approach)
Globalization has resulted in increasing transfer of firms operations, regardless of their size, to other countries. The recent dynamic emergence of China in the global economy, connecting with the vast inflows of foreign direct investment in their territory and common adjustments problems of many Western companies, has resulted in growing interest for best suitable business practices to this culturally and socially different environment. In this article, the key factors critical to the success of international companies in this region are introduced, with particular consideration to indigenous cultural elements and specific operation requirements of small and medium-sized enterprises in Business-to-Business sectors. The presented information are based on the broad literature review, five years of direct observation and thirty eight interviews conducted with Polish managers directly residing in China. In addition, some practical recommendations for managers and further research are given.Globalizacja wymusza na firmach, niezależnie od ich wielkości, coraz częstsze przenoszenie operacji do innych krajów. Dynamiczne pojawienie się Chin w światowej gospodarce i szeroki napł;yw zagranicznych inwestycji bezpośrednich na ich teren oraz problemy adaptacyjne wielu zachodnich przedsiębiorstw, spowodował;y zainteresowanie najlepszymi praktykami biznesowymi dostosowanymi do tego odmiennego kulturowo i społ;ecznie otocznia. W artykule zaprezentowane został;y najważniejsze czynnik mające wpł;yw na osiągnięcie sukcesu przez firmy międzynarodowe na tym obszarze, ze szczególnym uwzględnieniem aspektów kulturowych i specyfiki dział;ania mał;ych i średnich podmiotów na rynkach B2B. Prezentowane informacje są oparte na przeglądzie literatury, pięcioletnich obserwacjach bezpośrednich oraz trzydziestu ośmiu wywiadach przeprowadzonych z menadżerami polskich przedsiębiorstw odpowiedzialnymi za operacje w Chinach. Dodatkowo wskazano kilka praktycznych rekomendacji menadżerskich oraz możliwości dalszych badań
HATS-11b and HATS-12b: Two transiting Hot Jupiters orbiting sub-solar metallicity stars selected for the K2 Campaign 7
We report the discovery of two transiting extrasolar planets from the
HATSouth survey. HATS-11, a V=14.1 G0-star shows a periodic 12.9 mmag dip in
its light curve every 3.6192 days and a radial velocity variation consistent
with a Keplerian orbit. HATS-11 has a mass of 1.000 0.060 M, a
radius of 1.444 0.057 M and an effective temperature of 6060
150 K, while its companion is a 0.85 0.12 M, 1.510 0.078
R planet in a circular orbit. HATS-12 shows a periodic 5.1 mmag flux
decrease every 3.1428 days and Keplerian RV variations around a V=12.8 F-star.
HATS-12 has a mass of 1.489 0.071 M, a radius of 2.21
0.21 R, and an effective temperature of 6408 75 K. For HATS-12,
our measurements indicate that this is a 2.38 0.11 M, 1.35 0.17
R planet in a circular orbit. Both host stars show sub-solar metallicity of
-0.390 0.060 dex and -0.100 0.040 dex, respectively and are
(slightly) evolved stars. In fact, HATS-11 is amongst the most metal-poor and,
HATS-12 is amongst the most evolved stars hosting a hot Jupiter planet.
Importantly, HATS-11 and HATS-12 have been observed in long cadence by Kepler
as part of K2 campaign 7 (EPIC216414930 and EPIC218131080 respectively).Comment: 14 pages, 7 figures, 6 tables, submitted to A
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