A unified statistical model for S-N fatigue curves: probabilistic definition

In recent years, experimental tests exploring the gigacycle fatigue properties of materials suggest the introduction of modifications in well known statistical fatigue life models. Usual fatigue life models, characterized by a single failure mechanism and by the presence of the fatigue limit, have been integrated by models that can take into account the occurrence of two failure mechanisms and do not consider the presence of the fatigue limit. The general case, in which more than two failure mechanisms coexist with the fatigue limit, has not been proposed yet. The paper presents a unified statistical model which can take into account any number of failure mechanisms and the possible presence of the fatigue limit. The case of S-N curves with different fatigue life distributions coexisting for the entire stress range covered by fatigue tests is also considered. The adaptability of the statistical model to the S-N curves proposed in the open literature is demonstrated by qualitative numerical example

An evolutionary based dynamic energy management framework for IP-over-DWDM networks

We wish to thank COST (European Cooperation in Science and Technology), under Action IC0804 for their support of this wor

Solar polar orbiter : a solar sail technology reference study

An assessment is presented of a Solar Polar Orbiter mission as a Technology Reference Study. The goal is to focus the development of strategically important technologies of potential relevance to future science missions. The technology is solar sailing, and so the use of solar sail propulsion is, thus, defined a priori. The primary mission architecture utilizes maximum Soyuz Fregat 2-1b launch energy, deploying the sail shortly after Fregat separation. The 153 × 153 m square sail then spirals into a circular 0.48-astronomical-unit orbit, where the orbit inclination is raised to 90 deg with respect to the solar equator in just over 5 years. Both the solar sail and spacecraft technology requirements have been addressed. The sail requires advanced boom and new thin-film technology. The spacecraft requirements were found to be minimal because the spacecraft environment is relatively benign in comparison with other currently envisaged missions, such as the Solar Orbiter mission and BepiColombo

Differentials of fertility in North and South Gondar zones, northwest Ethiopia: A comparative cross-sectional study

<p>Abstract</p> <p>Background</p> <p>Ethiopia is one of the most densely populated countries in Africa with an estimated population of 77.1 million in mid-2007. Uncontrolled fertility has adversely influenced the socio-economic, demographic and environmental situations of the country. It is one of the largest and poorest countries that, even in the midst of crisis, has maintained high levels of fertility. This study was aimed at investigating the most important factors influencing fertility behavior in Northwest Ethiopia.</p> <p>Methods</p> <p>A comparative cross-sectional study which included 2424 women aged 25 years and above was undertaken in the Amhara region of Northwest Ethiopia. The study subjects were grouped into high fertile and low fertile categories. There were 1011 and 1413 women in the high and low fertile groups, respectively. A multi-stage cluster sampling stratified by place of residence was employed to select the required study subjects. Both bivariate and multivariate logistic regression techniques were used to analyze the data.</p> <p>Results</p> <p>Among the 25 variables considered in this study, only 9 of them were found significantly and independently associated with the level of fertility. Women with at least secondary education were at a lower risk of high fertility with OR = 0.37 (95% CI: 0.21 to 0.64) compared to those with no formal education. However, women with primary education did not show any significant difference when compared with the same baseline group. Age at first marriage was inversely associated with the number of children ever born alive. Place of residence, household expenditure, number of children who have died, attitude towards using contraceptives, women's knowledge on the safe period, and current marital status were the other variables that showed significant associations with the level of fertility.</p> <p>Conclusion</p> <p>Female education beyond the primary level, reduced infant and child mortality, delayed marriage and correct knowledge on the safe period during the menstrual cycle were amongst the main factors that had a bearing on high fertility.</p

NASA Grants #NAG5-12659 and #NAG5-12980 ACKNOWLEDGEMENTS

This master’s project would not have materialized without the support and assistance of several people. First and foremost, I express my deep gratitude to Dr. Prasad Gogineni, my thesis advisor and committee chair, for giving me the opportunity to work on this project. Thanks to Dr. David Andrews and Dr. John Gauch for serving on my thesis committee. I am deeply indebted to Mr. Torry Akins, my project supervisor, for conceiving the idea behind this project. Thanks also go to Mr. John Paden, whose insightful solutions bailed me out whenever I was in a quandary. Thanks to my friend Atul for reviewing the initial draft of this document. Last, but not least, I thank my parents and my siblings for their support and encouragement throughout the course of my stay at KU. This work was supported by the National Science Foundation (grant OPP-0122520) and NASA (grants NAG5-12659 and NAG5-12980). ii Radar depth sounder data collected as part of the Program in Arctic Regiona