The effect of state of cure on bond performance for an epoxy resin system

A study of the influence of the state and mode of cure of an epoxy resin, diglycidyl ether of bisphenol A cured with 4,4′-diaminodiphenylmethane, has been made. The state of cure was assessed by differential scanning calorimetry as residual heat of reaction and a transition temperature T^* corresponding to either the melting point or the glass transition temperature. The state of cure was varied by controlling both the time and temperature of cure. Bond strengths can be related to either T^g or residual heat of reaction, but the different cure schedules produce different relations; simultaneous measurement of both parameters is necessary to specify the state of cure. Some additional work has been carried out on the effect of delayed cure on bond performance and on the effect of varying the cure schedule for a phenol-formaldehyde adhesive. Both single- and double-overlap joints have been used and a constant single/double bond strength ratio has been found. This constant is different for the two adhesives, reflecting their different behavior in shear.     

The equivalence of the radial return and Mendelson methods for integrating the classical plasticity equations

The radial return method is a well-known algorithm for integrating the classical plasticity equations. Mendelson presented an alternative method for integrating these equations in terms of the so-called plastic strain—total strain plasticity relations. In the present communication, it is shown that, although the two methods appear to be unrelated, they are actually equivalent. A table is provided demonstrating the step by step correspondence of the radial return and Mendelson algorithms in the case of isotropic hardening.     

Managing Security in FPGA-Based Embedded Systems

FPGAs combine the programmability of processors with the performance of custom hardware. As they become more common in critical embedded systems, new techniques are necessary to manage security in FPGA designs. This article discusses FPGA security problems and current research on reconfigurable devices and security, and presents security primitives and a component architecture for building highly secure systems on FPGAs.     

The development of category-based induction: Reexamining conclusions from the induction then recognition (ITR) paradigm.

Three studies examined the development of category-based induction using an induction then recognition (ITR) procedure in which participants make category-based predictions about study items and are then given a surprise recognition test that requires discrimination between old and new category members. Exposure duration for study items was either self-paced (Experiment 1) or fixed for 5-year-olds and adults (Experiments 2a-b). Adults always showed a decrement in recognition performance following induction. Children showed the same decrement when exposure duration was equated across age groups. These results show that both young children and adults spontaneously access category-level information during induction. When study exposure time is self-paced, however, children may process additional, noncategorical aspects of study stimuli. (PsycINFO Database Record (c) 2010 APA, all rights reserved)