Artificial neural network model for steel–concrete bond prediction

In this paper, an Artificial Neural Network (ANN) is proposed for modelling the bond between conventional ribbed steel bars and concrete. The purpose is to predict the ultimate pull-out load from the concrete mix constituents (first ANN model) or the compressive strength (second ANN model) and from the steel bar diameter according to the RILEM test configuration [RILEM. Essai portant sur l’adhérence des armatures du béton: essai par traction. Materials and Structures 1970; 3 (3) 175–78]. The ANN models were implemented using an experimental database of 112 pull-out test results performed with ribbed bars 10 mm or 12 mm in diameter and three concrete mixes with different constituent proportions. A Multi-Layer-Perceptron was trained according to a back-propagation algorithm. The first model has six inputs (ANN-6): the diameter of the ribbed bar, the water to cement ratio, the gravel to sand ratio, the crushed to rolled gravel ratio, the type of cement and the concrete maturity. The second model has two inputs (ANN-2): the diameter of the bar and the concrete compressive strength. The ultimate pull-out load was the output data for both models.The results show that the implemented models have good prediction and generalisation capacity with low errors. The ANN-6 model is more accurate, regarding the generalisation capacity, than the ANN-2 model. Concrete mix constituents as input parameter, instead of the compressive strength, are more representative of the local phenomenon at the steel-ribs-to-concrete interface.     

Associative recognition of face pairs by younger and older adults: The role of familiarity-based processing.

Previous research suggested that older adults have a specific impairment in remembering verbal associative information, but it is unclear how elaboration and familiarity might influence this deficit in situations that involve perceptual processing. In the present experiments, younger and older participants studied male-female pairs of faces. Participants were then administered an associative recognition test consisting of previously studied pairs, pairs that contained previously studied items that were not studied together (i.e., conjunction pairs), and entirely new pairs of faces, and participants were instructed to identify pairs that had been presented together at study. Overall, participants were successful at recognizing previously presented pairs but were highly likely to mistakenly endorse conjunction pairs. This pattern was more pronounced for older adults, especially when items were repeated at encoding. Such data suggest that memory for face pairs relies largely on the familiarity of each face and not on a more precise recollection of associative information. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mental subtraction in high- and lower skilled arithmetic problem solvers: Verbal report versus operand-recognition paradigms.

The authors used the operand-recognition paradigm (C. Thevenot, M. Fanget, & M. Fayol, 2007) in order to study the strategies used by adults to solve subtraction problems. This paradigm capitalizes on the fact that algorithmic procedures degrade the memory traces of the operands. Therefore, greater difficulty in recognizing them is expected when calculations have been solved by reconstructive strategies rather than by retrieval of number facts from long-term memory. The present results suggest that low- and high-skilled individuals differ in their strategy when they solve problems involving minuends from 11 to 18. Whereas high-skilled individuals retrieve the results of such subtractions from long-term memory, lower skilled individuals have to resort to reconstructive strategies. Moreover, the authors directly confront the results obtained with the operand-recognition paradigm and those obtained with the more classical method of verbal report collection and show clearly that this second method of investigation fails to reveal this differential pattern. The rationale behind the operand-recognition paradigm is then discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The development of memory efficiency and value-directed remembering across the life span: A cross-sectional study of memory and selectivity.

Although attentional control and memory change considerably across the life span, no research has examined how the ability to strategically remember important information (i.e., value-directed remembering) changes from childhood to old age. The present study examined this in different age groups across the life span (N = 320, 5–96 years old). A selectivity task was used in which participants were asked to study and recall items worth different point values in order to maximize their point score. This procedure allowed for measures of memory quantity/capacity (number of words recalled) and memory efficiency/selectivity (the recall of high-value items relative to low-value items). Age-related differences were found for memory capacity, as young adults recalled more words than the other groups. However, in terms of selectivity, younger and older adults were more selective than adolescents and children. The dissociation between these measures across the life span illustrates important age-related differences in terms of memory capacity and the ability to selectively remember high-value information. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

A study on the texture diversity of the Artisan Ranchero Cheese from Central Mexico

The objective of the present study was to determine the diversity and causative factors in the textural profile of the Artisan Ranchero Cheese (ARC), a popular soft cheese made with raw cow's milk, which is consumed fresh. These factors included climatic conditions, production zone, cheese supplies, cheesemaking procedure and chemical attributes. Texture attributes were determined using texture profile analysis method. The relationship between texture and chemical attributes of the ARC were determined by a Factor Analysis. An Agglomerative Hierarchical Clustering Analysis was used to differentiate the ARC manufactures into groups. Two groups were identified, production zone being the variable which explained the variation in the data. Finally, a Discriminant Analysis was performed to determine standardisation of the ARC attributes through the sampling periods. The 89% of cheese samples were correctly classified into their own cheese manufacture. This last analysis demonstrated that there was an important degree of standardisation of the cheesemaking procedure within each cheese manufacture, something that was not demonstrated before with artisan cheesemakers.     

Failure modes and failure mechanisms of RC members strengthened by NSM CFRP composites – Analysis of pull-out failure mode

The aim of the experimental programme developed in this work was to study the failure modes and the pull-out failure mechanism of RC members strengthened by Near Surface Mounted reinforcement (NSM) technique. The global behaviour of reinforced concrete beams strengthened by NSM and subjected to flexure was investigated. The rods were 6- and 12-mm-diameter carbon–epoxy pultruded FRP. Two vibrated concrete compositions were tested: conventional (VC30) and high-strength (VC60), and one filling material: epoxy resin. The study was carried out up to the failure load, and focused on the failure modes of the beams. The experimental results were compared with the analytical model for the pull-out failure mode of FRP rods. Based on the concept of the anchorage length beyond the last crack, the calculation gives a good approximation of the ultimate bond stress in the cross-section located at the last crack.     

A small,high‐efficiency diesel generator for high‐altitude use in Antarctica

We have characterised a small, high‐efficiency diesel generator selected to power remote experiments on the Antarctic plateau at altitudes of up to 5000 m. We describe the design of an environmental chamber to simulate these high altitudes and present an experimental investigation of the engine operation at high altitude on Jet A‐1, comparing this to the engine's performance at sea level. Although attention must be paid to the provision of adequate cooling, no modification to the engine itself is required. Our final system provides very high reliability and produces 1500 W of electrical power with a fuel consumption of 280 g kWh⁻¹. A bank of ultracapacitors is used to start the engine in the cold environment of Antarctica. We describe the low‐temperature operation and survival tests that we performed on the ultracapacitors and the engine. Copyright © 2009 John Wiley & Sons, Ltd.     

Memory predictions are influenced by perceptual information: Evidence for metacognitive illusions.

Although perceptual information is utilized to judge size or depth, little work has investigated whether such information is used to make memory predictions. The present study examined how the font size of to-be-remembered words influences predicted memory performance. Participants studied words for a free-recall test that varied in font size and made judgments of learning (JOLs) for each item. JOLs were influenced by font size, as larger font sizes were given higher JOLs, whereas little relationship was evident between font size and recall. The effect was modified when other, more valid, sources of information (e.g., associative strength) were available when JOLs were made and persisted despite experience with multiple study-test sessions, use of a forgetting scale to assess predictions, and explicit warning of participants that font size has little effect on memory performance. When ease of reading was manipulated, such that large font size words were made less fluent, the effect was eliminated. Thus, highly accessible perceptual cues can strongly influence JOLs, likely via encoding fluency, and this effect can lead to metacognitive illusions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)