LOCA frequency evaluation using expert elicitation

The double-ended-guillotine break (DEGB) criterion of the largest primary piping system in the plant, which generally provides the limiting condition for the emergency core cooling system requirements, is widely recognized as an extremely unlikely event. As a result, US Nuclear Regulatory Commission (NRC) staff are currently considering a risk-informed revision of the design-basis break size requirements for commercial nuclear power plants. In support of this effort, loss-of-coolant accident (LOCA) frequency estimates have been developed using an expert elicitation process by consolidating service history data and insights from probabilistic fracture mechanics (PFM) studies with knowledge of plant design, operation, and material performance. Baseline LOCA frequency estimates for the 5th percentile, median, mean and 95th percentile were determined from each panelist's elicitation responses. Group estimates were determined by aggregating the individual estimates using the geometric mean of the individual estimates for each frequency parameter. Group variability was estimated by calculating 95% confidence bounds for each of the group frequency parameters (i.e., median, mean, and 5th and 95th percentiles). A number of sensitivity analyses were conducted to examine the effects on the quantitative results from varying the assumptions, structure and techniques of the baseline analysis procedure.     

Force-Deformation Behavior of Isolation Bearings

The isolation bearings are widely used in earthquake prone areas to protect the structure from seismic forces. The isolation bearing consists of an isolator to increase the natural period of the structure away from the high-energy periods of the earthquake, and a damper to absorb energy in order to reduce the seismic force. The most common isolation bearings used are lead–rubber bearings. They combine the function of isolation and energy dissipation in a single compact unit, giving structural support, horizontal flexibility, damping, and a centering force in a single unit. The relation between the horizontal force and horizontal displacement of the isolation bearings is nonlinear; to calculate the stiffness and the damping constant, which correspond to effective design displacement, the nonlinear behavior is expressed by bilinear behavior. This technical note presents new relations to calculate yield force, horizontal displacement, and damping.     

Hydrology and Nitrogen Components of a Simple Rye Growth Model

Cover cropping practices are being researched to reduce artificial subsurface drainage nitrate-nitrogen (nitrate-N) losses from agricultural lands in the upper Mississippi watershed. A soil-plant-atmosphere simulation model, RyeGro, was developed to quantify the influence of a winter cereal rye cover crop on nitrate-N losses given climatic variability in the region. This paper describes the hydrology and nitrogen cycle submodels of RyeGro, which was developed with a low level of complexity and conceptualizes the soil profile as three soil layers. The model was calibrated with data from a three-year rye cover crop field study conducted at Lamberton, Minnesota, and validated with data from a previous study. During model calibration, field subsurface drainage nitrate-N loadings were predicted within 0.2, 0, and 1.6?kg?N?ha?1 (1, 0, and ?3%) of measured loadings for the corn-soybean treatment and within 1.2, 0, and 1.6?kg?N?ha?1 (11, 0, and 3%) of measured loadings for the corn-rye-soybean treatment. The model validation showed nitrate-N loading differences of 7 and 1?kg?N?ha?1 (?22 and 4%) for the two years tested.     

Facial dynamics as indicators of trustworthiness and cooperative behavior.

Detecting cooperative partners in situations that have financial stakes is crucial to successful social exchange. The authors tested whether humans are sensitive to subtle facial dynamics of counterparts when deciding whether to trust and cooperate. Participants played a 2-person trust game before which the facial dynamics of the other player were manipulated using brief (     

Combining propensity score matching and group-based trajectory analysis in an observational study.

In a nonrandomized or observational study, propensity scores may be used to balance observed covariates and trajectory groups may be used to control baseline or pretreatment measures of outcome. The trajectory groups also aid in characterizing classes of subjects for whom no good matches are available and to define substantively interesting groups between which treatment effects may vary. These and related methods are illustrated using data from a Montreal-based study. The effects on subsequent violence of gang joining at age 14 are studied while controlling for measured characteristics of boys prior to age 14. The boys are divided into trajectory groups based on violence from ages 11 to 13. Within trajectory group, joiners are optimally matched to a variable number of controls using propensity scores, Mahalanobis distances, and a combinatorial optimization algorithm. Use of variable ratio matching results in greater efficiency than pair matching and also greater bias reduction than matching at a fixed ratio. The possible impact of failing to adjust for an important but unmeasured covariate is examined using sensitivity analysis. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Response inhibition deficit is involved in poor decision making under risk in nonamnesic individuals with alcoholism.

Individuals with alcoholism exhibit poor decision making as reflected by their continued alcohol use despite encountering problems and by low performance in laboratory tasks of decision making. Here, the authors investigated the relative contribution of several distinct processes of executive functions in performance on the Iowa Gambling Task (IGT; A. Bechara, A. R. Damasio, H. Damasio, & S. W. Anderson, 1994) in recently detoxified individuals with alcoholism. Compared to matched healthy participants, individuals with alcoholism showed below-normal scores in the last 20 trials of the IGT as well as on other tasks of executive functions, specifically those assessing the capacity to manipulate information stored in working memory, detect abstract rules, or inhibit prepotent responses. Prepotent response inhibition best predicted performance in the late trials of the IGT, that is, when participants have likely acquired knowledge about the reward/punishment contingencies of the task. These results underline the important role that response inhibition plays in decision making, especially in risky situations, when knowledge of the probability of a given outcome becomes available (i.e. decisions under risk). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

"Task control and cognitive abilities of self and spouse in collaboration in middle-aged and older couples": Erratum.

Reports an error in "Task control and cognitive abilities of self and spouse in collaboration in middle-aged and older couples" by Cynthia A. Berg, Timothy W. Smith, Kelly J. Ko, Nancy J. M. Henry, Paul Florsheim, Gale Pearce, Bert N. Uchino, Michelle A. Skinner, Ryan M. Beveridge, Nathan Story and Kelly Glazer (Psychology and Aging, 2007[Sep], Vol 22[3], 420-427). Due to an editing mistake, the order of authorship was incorrect. The correct order is as follows: Berg, Smith, Ko, Beveridge, Story, Henry, Florsheim, Pearce, Uchino, Skinner, & Glazer. (The following abstract of the original article appeared in record 2007-13103-002.) Collaborative problem solving may be used by older couples to optimize cognitive functioning, with some suggestion that older couples exhibit greater collaborative expertise. The study explored age differences in 2 aspects of collaborative expertise: spouses' knowledge of their own and their spouse's cognitive abilities and the ability to fit task control to these cognitive abilities. The participants were 300 middle-aged and older couples who completed a hypothetical errand task. The interactions were coded for control asserted by husbands and wives. Fluid intelligence was assessed, and spouses rated their own and their spouse's cognitive abilities. The results revealed no age differences in couple expertise, either in the ability to predict their own and their spouse's cognitive abilities or in the ability to fit task control to abilities. However, gender differences were found. Women fit task control to their own and their spouse's cognitive abilities; men only fit task control to their spouse's cognitive abilities. For women only, the fit between control and abilities was associated with better performance. The results indicate no age differences in couple expertise but point to gender as a factor in optimal collaboration. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Causes of Weak-localization of Electrons on Liquid Helium

We have investigated the dephasing processes in a weak localization (WL) experiment of a two-dimensional electron system on liquid helium. From low-field magnetoconductivity measurements we can separate the damping of WL on the dephasing of electrons due to electron–electron interaction and the motion of the helium vapour atoms. We observe an intermediate regime where both damping mechanisms are of comparable importance and determine the cross-over from one dominant regime to the other.     

Human-in-the-Loop Camera Control for a Mechatronic Broadcast Boom

Platforms like gantries, booms, aircrafts, and submersibles are often used in the broadcasting industry. To avoid collisions and occlusions, such mechatronic platforms often possess redundant degrees-of-freedom (DOFs). As a result, manual manipulating of such platforms demands much skill. This paper describes the implementation of several controllers that, by using computer vision, attempts to reduce the number of manually manipulated DOFs. Experiments were performed to assess the performance of each controller. A model for such a system was developed and validated. To determine how the visual servoing can improve the tracking, a novice operator and an expert were asked to manually track a moving target with the assistance of visual servoing. The results of these tests were analyzed and compared     

Microstructural considerations for ultrafine lead free solder joints

As solder joints become increasingly miniaturised to meet the challenging demands of future electronic packaging, it is vitally important to consider whether the solder joint size and geometry could become a reliability issue and thereby affect the implementation of the Pb-free solders. In this study, different bumping techniques, e.g., solder dipping, stencil printing followed by solder reflow, and electroplating of solders and subsequent reflow, were used to investigate the microstructure and interfacial interactions of molten Sn and Sn-based Pb-free solders on different metallizations, e.g., copper and electroless nickel immersion gold (ENIG). The resultant microstructures from a variety of pad sizes, ranging from 1 mm down to 25 μm, and representing different solder bump geometries have been investigated. In addition, thermodynamic and combined thermodynamic-kinetic modelling has been used in order to understand the microstructure of Pb-free solders, the kinetics of dissolution of the metallizations and the formation of interfacial intermetallic compounds (IMCs). Both the experimental results and theoretical predictions suggest that the solder bump size and geometry can influence the as-soldered microstructure. In the light of the increasing importance of the microstructural features of the ultrafine solder joint in determining its long term reliability, a novel computational interface between software for thermodynamic calculations, high-level scientific computing and multiphysics modelling, is introduced. This modelling methodology provides a potential platform for microstructure-based Finite Element (FE) reliability modelling of ultrafine interconnects for future microelectronic products.