Study and Analysis of the Stress State in a Ceramic, Button-Head, Tensile Specimen

The final results are reported for a study to identify and correct the causes of nongage-section failures (notably button-head failures) in ceramic tensile specimens observed in several laboratories. Numerical modeling of several candidate specimen gripping systems has shown inherent stress concentrations near the specimen button head at which the maximum stress may approach 75 to 100% of the gage-section stress for certain grip conditions. Empirical comparisons of both tapered- and straight-collet gripping systems revealed compromises in both systems. The straight-collet system, with deformable collets, is simpler to use but produces statistically significant greater average percent bending for all tests than those produced for the tapered-collet system, which is slightly more difficult to use. Empirical tensile tests of {approx}50 aluminium oxide and {approx}50 silicon nitride specimens were conducted to evaluate the loading capability of both gripping systems, the percent bending in each system, and the potential of consistently producing successful test results. These tests revealed that, due to variations in individual specimens or the individual specimen/grip interfaces, neither of the gripping systems can consistently produce bending of less than 3 to 4% at failure although occasional values of {approx}0.5% bending were attained. Refinements of grinding procedures and dimensional measurement techniques have shown critical details in both the practices and consistency of machining necessary for achieving the dimensional tolerances while minimizing subsurface damage. Numerical integration techniques indicate that up to a consistent 5.0% bending during fast-fracture tests can be tolerated before large influences are detected in the determination of the Weibull modulus and the Weibull characteristic strength

Validation of spallation neutron production and propagation within Geant4

Using simulations to understand backgrounds from muon-induced neutrons is important in designing next-generation low-background underground experiments. Validation of relevant physics within the Geant4 simulation package has been completed by comparing to data from two recent experiments. Verification focused on the production and propagation of neutrons at energies important to underground experiments. Discrepancies were observed between experimental data and the simulation. Techniques were explored to correct for these discrepancies.Comment: 12 pages, 6 figures, 5 tables, submitted to NIM A. 6 Aug 200

Patterns and outcomes of preterm hospital admissions during pregnancy in NSW, 2001-2008

Contains fulltext : 139362.pdf (publisher's version ) (Open Access

Multifetal pregnancies: preterm admissions and outcomes

Objective. To describe the rates of antenatal hospital admission during twin or higher order multifetal pregnancies, and the admission outcomes as discharge undelivered, transfer to higher care, or spontaneous or elective delivery. Methods. Cohort study using linked birth and hospital data. The cohort comprised women who gave birth to twins or higher order multiple infants of ≥ 24 weeks gestation in 2001–2008 and who were admitted to hospital in weeks 20–36 of the pregnancy. Results. In 63.4% of 10 779 twin pregnancies and 99.5% of 197 triplet and quadruplet pregnancies, the woman was admitted to hospital at least once in weeks 20–36 of the pregnancy, for a total 10 985 admissions. Almost half the admissions (46.3%) ended in discharge without delivery, 10.7% in transfer to higher care, 21.1% in spontaneous labour and birth, and 21.8% in elective delivery (induction or prelabour Caesarean section). The reason for admission was preterm labour in 34.2% of admissions. Conclusions. Hospital admission during pregnancy is common for women with multifetal pregnancies, with many of these admissions resulting in preterm birth. This is the first study to report the rate of pregnancy admissions for women with multifetal pregnancies, and provides a baseline for future studies of hospital use in this population. What is known about the topic? Multifetal pregnancies are high risk and require greater medical care than singleton pregnancies. However, few studies specifically examine multifetal pregnancies, and most pregnancy studies exclude them, so there is little known about the resource use of this group. What does this paper add? This is the first paper to report population rates of hospital admission during pregnancy for women with multifetal pregnancies. We report the admission rates, and the admission outcomes as discharge undelivered, transfer to higher care or spontaneous or elective delivery. What are the implications for practitioners? Most women with multifetal pregnancies are admitted to hospital at least once during the pregnancy, with 51% of these admissions resulting in preterm delivery. Of those discharged undelivered, 60% were admitted for 1 day or less. This has implications for resource use, proposed place of birth and for practitioners advising pregnant women. </jats:p

Determination of atomic abundances of solar-type stars

We discuss the results of abundance determinations of the solar-type stars HD 1835 and HD 10700 using our new procedure. This procedure has the advantage of automated pipeline usage for large amounts of spectroscopic data, with minimal user input. It is based on the spectral synthesis method, where the best values are found with our own developed minimization technique. We reduce the number of free parameters in minimization space using the fit to the observed atomic iron lines. We calibrated our procedure using fits to the observed solar spectrum. Then we determined abundances in two solar-type stars, namely the metal-deficient star HD 10700 and the metal-rich star HD 1835. We found good agreement with previously published results. Thus, we aim to use this procedure for the abundance determination of solar-type stars, particularly planet hosting stars, where the knowledge of abundances is crucial for our understanding of their evolution and formation processes

A Technique for Tensile Fatigue and Creep Testing of Fiber-Reinforced Ceramics

An experimental technique for the elevated temperature tensile fatigue and creep testing of fiber-reinforced ceramics is discussed. The experimental approach utilizes edge-loaded specimens with rectangular gage-sections. Novel furnace and grip designs which allow testing in air to 1500°C are provided. The specimen, furnace and grip designs discussed in the paper have been successfully used to test unidirectional and cross-ply SiCf/Si3N 4, SiCf/SiC, Cf/SiC and SiCf/calcium-aluminosilicate composites.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66679/2/10.1177_002199839202600608.pd

Proposal of a suitable insurable portfolio for a municipality Budišov

Diplomová práce se zabývá problematikou, která souvisí s návrhem pojistného portfolia pro obec Budišov. Na základě aktiv obce a analýzy rizik je navrhnuto takové pojistné portfolio, díky kterému budou nejzávažnější rizika obce prostřednictvím komerční pojišťovny minimalizována.This diploma thesis deals with the problems related to insurance protection for municipality Budišov. The insurance portfolio is suggested on the basis of municipality assets and analysis of all risks. It helps to minimize the most serious risks of its activities through the commercial insurance company.

Spontaneous Breaking of Lorentz Invariance

We describe how a stable effective theory in which particles of the same fermion number attract may spontaneously break Lorentz invariance by giving non-zero fermion number density to the vacuum (and therefore dynamically generating a chemical potential term). This mecanism yields a finite vacuum expectation value $$which we consider in the context of proposed models that require such a breaking of Lorentz invariance in order to yield composite degrees of freedom that act approximately like gauge bosons. We also make general remarks about how the background source provided by$$ could relate to work on signals of Lorentz violation in electrodynamics.Comment: revtex4, 11 pages, 5 figures; v2:references added; v3:more references added, typos fixed, some points in sect. IV clarified; v4:even more references added, discussion in sect. V extended; v5:replaced to match published version (minor corrections of form