Electrochemical Sensors for Nondestructive Evaluation of Adhesive Bonds

An in-situ corrosion sensor based on electrochemical impedance spectroscopy (EIS) has been used to detect moisture ingress into aluminum-aluminum and aluminum-composite adhesive bonds. Both wedge tests and tensile button tests (aluminum-aluminum bonds only) were performed. Upon moisture absorption, the impedance spectra change shape with the low-frequency region becoming resistive. The low-frequency impedance decreases by several orders of magnitude, depending on the adhesive and the experimental conditions. For bonds with stable interfaces, such as phosphoric acid anodized (PAA) aluminum, the absorbed moisture causes an initial weakening of the adhesive resulting in reduced strength or small crack propagation. A substantial incubation time prior to substrate hydration and bond degradation allows warning of potential joint deterioration and enables condition-based maintenance. For bonds with smooth interfaces with little or no physical bonding (mechanical interlocking), crack propagation can proceed interfacially with minimal moisture absorption. A comparison of the incubation times for Forest Products Laboratory (FPL, or sulfuric acid-sodium dichromate) etched surfaces, both bonded to epoxy adhesives and freely exposed to water or humidity at different temperatures, shows that hydration occurs with the same activation energy and, hence, the same mechanism, independent of whether or not the surface is covered with adhesive. However, the pre-exponential factor in the rate constant is dependent on the concentration of free moisture at the interface so that the hydration rate varies by several orders of magnitude.     

Scheduling UET-UCT tasks: branch-and-bound search in the priority space

The paper is concerned with the problem of scheduling partially ordered unit execution time tasks on parallel processors with unit communication delays and release times. Two criteria are considered, the maximum lateness and its particular case, the makespan. This problem plays an important role in scheduling theory and was originally inspired by the applications to multi-processor computer systems. It is well known that for both criteria the problem is NP-hard in the strong sense. The paper presents an implementation of the branch-and-bound method which does not partition the feasible region explicitly. The theoretical results are complemented by computational experiments.     

Defining Media Enjoyment as the Satisfaction of Intrinsic Needs

This article presents a model of enjoyment rooted in self‐determination theory ( Deci & Ryan, 1985 ) that includes the satisfaction of three needs related to psychological well‐being: autonomy, competence, and relatedness. In an experiment designed to validate this conceptualization of enjoyment, we manipulate video game characteristics related to the satisfaction of these needs and examine their relative effects on enjoyment. The validated model explains 51% of the variance in enjoyment, even without including needs usually studied in relation to enjoyment such as pleasure seeking. Results indicate the utility of defining enjoyment as need satisfaction. These results are discussed in terms of a broader conceptualization of enjoyment represented as the satisfaction of a comprehensive set of functional needs.     

Parental Mediation of Children's Television Viewing in Low-Income Families

Studies of parental mediation of children's television viewing have included samples of mostly middle- and upper-class Caucasian parents. These studies have only begun to examine mediation in the context of parent-child relationships. This study of 306 low-income, predominately African American mothers assesses macro- and microlevel influences on viewing mediation using Bronfenbrenner's ecological theory of child development. It was hypothesized that factors outside the home (e.g., work hours) influence parents' involvement with children, which, in turn, was predicted to influence viewing mediation. Results supported this model for coviewing and instructive mediation, but not for viewing restrictions.     

Corrigendum to Example 4 in “μ-Bases for complex rational curves” [Computer Aided Geometric Design 30 (2013), 623–635]

We made a mistake in Example 4 in the paper Wang and Goldman (2013). Here we correct this mistake.     

Forgetting all else: On the antecedents and consequences of goal shielding.

Six studies explore the role of goal shielding in self-regulation by examining how activation of focal goals to which the individual is committed inhibits the accessibility of alternative goals. Consistent evidence was found for such goal shielding, and a number of its moderators were identified: Individuals' level of commitment to the focal goal, their degree of anxiety and depression, their need for cognitive closure, and differences in their goal-related tenacity. Moreover, inhibition of alternative goals was found to be more pronounced when they serve the same overarching purpose as the focal goal, but lessened when the alternative goals facilitate focal goal attainment. Finally, goal shielding was shown to have beneficial consequences for goal pursuit and attainment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)