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51.
Julie K. Furmick Dr. Ichiro Kaneko Angela N. Walsh Joanna Yang Jaskaran S. Bhogal Geoffrey M. Gray Juan C. Baso Drew O. Browder Jessica L. S. Prentice Luis A. Montano Chanh C. Huynh Lisa M. Marcus Dorian G. Tsosie Jungeun S. Kwon Alexis Quezada Nicole M. Reyes Brittney Lemming Puneet Saini Dr. Arjan van der Vaart Dr. Thomas L. Groy Dr. Pamela A. Marshall Dr. Peter W. Jurutka Dr. Carl E. Wagner 《ChemMedChem》2012,7(9):1551-1566
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Thomas R. Bieler Bite Zhou Lauren Blair Amir Zamiri Payam Darbandi Farhang Pourboghrat Tae-Kyu Lee Kuo-Chuan Liu 《Journal of Electronic Materials》2012,41(2):283-301
Because failures in lead-free solder joints occur at locations other than the most highly shear-strained regions, reliability
prediction is challenging. To gain physical understanding of this phenomenon, physically based understanding of how elastic
and plastic deformation anisotropy affect microstructural evolution during thermomechanical cycling is necessary. Upon solidification,
SAC305 (Sn-3.0Ag-0.5Cu) solder joints are usually single or tricrystals. The evolution of microstructures and properties is
characterized statistically using optical and orientation imaging microscopy. In situ synchrotron x-ray measurements during thermal cycling are used to examine how crystal orientation and thermal cycling history
change strain history. Extensive characterization of a low-stress plastic ball grid array (PBGA) package design at different
stages of cycling history is compared with preliminary experiments using higher-stress package designs. With time and thermal
history, microstructural evolution occurs mostly from continuous recrystallization and particle coarsening that is unique
to each joint, because of the specific interaction between local thermal and displacement boundary conditions and the strong
anisotropic elastic, plastic, expansion, and diffusional properties of Sn crystals. The rate of development of recrystallized
microstructures is a strong function of strain and aging. Cracks form at recrystallized (random) boundaries, and then percolate
through recrystallized regions. Complications arising from electromigration and corrosion are also considered. 相似文献
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Graduated driver licensing (GDL) programs are specialized licensing systems for beginner drivers adopted in all U.S. states, Australia, Canada, and New Zealand. GDL programs reduce novice drivers’ exposure to high-risk driving situations while they gain driving experience. Several studies document the success of GDL programs overall in reducing young teen crash rates. However, little is known about which specific components of these programs (e.g., nighttime driving restrictions) and which calibrations of these components (e.g., 10 PM, 11 PM, 12 AM, or 1 AM), are associated with the largest crash reductions. The goal of this study was to identify the GDL component calibrations associated with the largest reductions in fatal crash involvements for 16–17-year-olds. Driver fatal crash involvements for all U.S. states from 1986 to 2007 were analyzed using Poisson regression models to estimate the association of various GDL component calibrations with 16- and 17-year-old driver fatal crash incidence, after adjusting for potential confounders. We found clear evidence that (a) a minimum learner permit holding period of 9–12 months and (b) a passenger restriction allowing only one teen passenger for 6 months or longer are the calibrations for the learner permit holding period and passenger restriction components associated with the largest reductions in 16–17-year-old driver fatal crash involvements. Additionally, the data suggest that (a) disallowing learner driving until age 16, (b) disallowing intermediate licensure until age 16½ to 17, and (c) a nighttime driving restriction starting at 10 PM or earlier are the calibrations for these components associated with the largest reductions in 16-year-old driver fatal crashes. There was no clear evidence to support particular calibrations for supervised driving hours or unrestricted license ages. 相似文献
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Erol Hakanoglu Myron B Fiering E. A. C. Croucht Richard Wilsont Lauren Zeise 《Civil Engineering and Environmental Systems》2013,30(2):84-96
Based on previous work, this paper aims to show how approximate methods of estimating exposure can lead to a preliminary ranked list of chemicals for regulation of carcinogens. This list is likely to be more reliable, than those so far generated. The paper argues four main points. Firstly that an indication of the route by which the total production of a hazardous material is distributed and enters the human body should be explicitly included in calculations. Second, simple calculations based on conservative bounds should be made to establish a ranking or set of priorities for regulation. Third, an improved system for establishing regulatory priorities can be based on formal analysis using regret functions. Finally some simple, bounded, calculations based on commonly used herbicides and pesticides are made and it is shown how some regulatory processes could be modified. 相似文献
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