The “Chunnel” Fire.?II: Analysis of Concrete Damage

In Part I of this study, a material model for the in-situ behavior of rapidly heated concrete was developed that accounts explicitly for the dehydration of concrete and its cross-effects with deformation (chemomechanical couplings) and temperature (chemothermal couplings). In this part of the study, the model is used in finite-element analysis of the tunnel rings of the Channel Tunnel (the “Chunnel”) exposed to fire. An analysis of the finite-element results—i.e., the profiles of temperature, dehydration, stresses, and plastic strains—clearly shows that the thermal spalling that occured during the Chunnel fire is initiated by an in-plane biaxial compressive stress clog closed to the heated surface. The compressive stresses are caused by restrained thermal dilatation and are bounded by chemoplastic softening due to dehydration. They provoke permanent radial deformation, which can be attributed to spalling. The role of thermal damage and thermal decohesion is discussed by comparing elastic, chemoelastic, and chemoplastic stress developments during the 10 h fire exposure. It is found that the salient feature to capture the initiation of thermal spalling at a structural level is the chemoplastic softening behavior at a constitutive material level. It is also shown that a reinforcement on the cold-side, as well as steel fiber reinforcement of concrete, in tunnel rings may significantly increase the risk of thermal spalling.     

Water Migration Phenomenon Model in Cracked Concrete.?I: Formulation

A mathematical model for water migration in concrete that changes from a homogeneous to a nonhomogeneous material due to its loading history is developed in detail. In the proposed model, concrete is assumed to be composed of aggregate, cement paste, water, a crack band, and an interfacial crack between the aggregate and cement paste. The discontinuities for displacement and hydraulic gradient on cracks are considered on the microlevel. Then the governing equation for water migration in concrete as a homogeneous and a nonhomogeneous material is developed by coupling the mass conservation law and the force equilibrium. Therefore, it is possible to apply the developed model not only to cement-based material but also to porous permeable material like soil material and rock. However, the applicability of the developed model must be confirmed by comparing the experimental results.     

Compound Size Effect in Composite Beams with Softening Connectors.?I: Energy Approach

The size effect on the nominal strength of steel-concrete composite beams caused by shear failures of connectors such as welded studs is analyzed by two different approaches: (1) In this paper (Part I) by a fracture type analysis of the energy release caused by propagation of the zone of failed connectors along the beam; and (2) in a companion paper (Part II) by a direct solution of the load-deflection diagrams from the differential equations of beam bending theory. The former can capture the large size asymptotic size effect and yields simple formulas suitable for design, whereas the latter can provide the solution for small beam sizes for which the connector failure zone is not much shorter than the span. The force-slip diagram of the connectors exhibits postpeak softening, which engenders an energetic size effect on the nominal strength of the connector. If the connectors are geometrically scaled with the beam, the size effect in the shear failure of connectors (mesoscale) is superimposed on the size effect due to propagation of the zone of connector failures along the beam (macroscale), producing in the beam as a whole a compound size effect that is stronger than in linear elastic failure mechanics. If the connector sizes and the interface area per connector are not scaled with the overall dimensions of the composite beam, the size effect law proposed by Ba?ant in 1984 is applicable. Comparisons with available test results are presented in Part II.     

The G.P. zones in AlCu alloys—I

Absolute measurements of the diffuse X-ray scattering from an Al-1.94 at.% Cu single crystal aged 1 hr at 353 K into the G.P.1 state have been made at a synchrotron source. It is confirmed that this state consists of a mixture of single and multilayer zones on {100} planes of the matrix, and essentially 100% copper. The multilayer zones have roughened or incomplete surfaces. Due to the high intensity and resolution of such an X-ray source, the interatomic displacements are obtained to a high precision for the first time. These displacements indicate that the interplanar strains parallel and normal to the zone faces oscillate in sign. For the single layer zones, the nearest Al plane collapses toward the zone by ~ 10%, whereas the next plane moves away by a similar amount. These displacements vanish near the fourth or fifth At plane. The strains near the multilayer zones are similar.     

The “me” I claim to be: Cultural self-construal elicits self-presentational goal pursuit.

In 12 studies, respondents with an independent (vs. interdependent) self-construal showed an increased tendency and readiness to present themselves as skillful and capable and a decreased tendency and readiness to present themselves as socially sensitive and appropriate. This emerged in the form of differential scores on direct measures of self-presentation—self-deceptive enhancement and impression management (Study 1), differential social sensitivity in a gift-giving scenario (Study 2), differential performance on questions assessing general knowledge (Studies 5–6) and etiquette (Studies 7–8), and different choices between tests purportedly measuring one’s self-reliance versus social-appropriateness (Studies 9A and 9D). These relationships were observed when participants focused on their own self-presentational concerns but disappeared when participants focused on others’ outcomes (Study 3) or when they had a prior opportunity to satisfy their goals via self-affirmation (Studies 4, 5, 6, 7, 8, 9B, 9D). Finally, self-construal effects were eliminated or reversed when participants were led to doubt their ability to achieve their self-presentational goals (Study 9C). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cooperating when “you” and “I” are treated fairly: The moderating role of leader prototypicality.

We developed a model predicting that leaders are most effective in stimulating follower cooperation when they consistently treat all group members in a fair manner and are prototypical (i.e., representative of the group's values and norms). In support of this idea, we consistently found that group members cooperated most when prototypical leaders treated themselves as well as their coworkers fairly across a laboratory experiment and 3 cross-sectional field studies. These findings highlight the important role of others' fairness experiences and perceptions in influencing one's own reactions and also the role of leaders as representing the group's values and norms. We discuss implications for fairness theory and the leader prototypicality literature. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

“The disadvantaged psychological scene”: Educational experiences of women in early Canadian psychology.

This article discusses three distinct patterns that characterise the educational experiences of prominent women psychologists who obtained their PhDs in Canada prior to the 1950s. First, these women obtained their PhDs in psychology in Central Canadian universities versus universities in Western or Eastern Canada. Second, these women made a later entrance into the field of psychology compared with the early prominent women psychologists in the United States. Finally, most of the prominent women in early Canadian psychology did not encounter barriers to attaining their PhDs. This article provides a necessary first step toward constructing a more complete history of women in early Canadian psychology. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Grain boundaries in Ni3Al—I. The local compositional order

The local compositional order in the vicinity of grain boundaries in Ni₃Al, with and without boron, was examined using lattice imaging techniques. It was shown that small angle twist, tilt and mixed boundaries and large angle (near Σ = 5) twist boundaries were ordered up to very close to the interface plane. A compositionally disordered region ∼ 1.5 nm thick is present in the vicinity of a large angle general boundary in boron-doped Ni₃Al. Two large angle general boundaries are ordered up to very close to the interface in boron-free Ni₃Al. Image simulations were performed to identify possible imaging artifacts due to inclination of the boundary plane away from being edge-on. It was shown that the experimental observations of a locally disordered region cannot be explained as being an imaging artifact.     

Review: The “butterfly effect” in continuous casting

Abstract

Technology is born, exists over a lifespan and dies. Maybe it also lives! Some processes or products are superseded by new ones, somewhat easily, whereas others survive for extended periods. The blast furnace process is one which continues to evolve and improve, through Blast furnace specific developments, but also by adoption and adaption of other technologies. It is not easy to replace blast furnaces all over the world with a new process – the magnitude of the task is too big. Even partial replacement has turned out to be quite a task. In today's world, a new technology has to be substantially better than the existing one in terms of safety, ease of operation and control, operating and capital cost, ability to recover from disasters, ability to survive when the conditions around it change and environmental impact. A genus of a technology that is continuously evolving through mutation or otherwise is difficult to replace, but new species will continue to spring up to challenge the dominant one.     

An in situ study of prismatic glide in magnesium—I. The rate controlling mechanism

In situ experiments have been performed in magnesium single crystals, oriented so as to inhibit basal glide, in order to study the glide mechanism of a dislocations in prismatic planes, between 50 and 650 K. In the first part of this study, the observation of rectilinear screw dislocations, submitted to a strong friction force, leads to the conclusion that the strain rate is controlled by the Friedel-Escaig mechanism, in the whole temperature range. The corresponding macroscopic activation area is discussed, and the athermal temperature is estimated as higher than 700 K. Dislocation multiplication occurs like in b.c.c. metals, on fixed sources, and on closed and open dislocation loops. Creep of magnesium is then reinterpreted in terms of the present results.     

Rapidly solidified AlCu alloys—I. experimental determination of the microstructure selection map

Laser rapid solidification experiments have been performed on AlCu alloys of hypereutectic composition 36, 40 and 44 wt% Cu. By taking thin foils from the surface of the laser traces it has been possible to study the resulting growth morphologies using TEM; the microstructural orientation allowing the morphologies to be correlated with their local growth velocities. Microstructural orientation allowing velocity range 0.01–2.0 ms⁻¹ have been studied, and eutectic (both with and without oscillatory) instabilities), dendritic, cellular, banded and planar front growth have all been observed. By combining these results with earlier observations made on alloys with lower Cu concentrations, it has been possible to produce a microstructure selection map for AlCu alloys. The map correlates microstructure to growth velocity and composition in the ranges 0.01–2.0 ms⁻¹ and 0–44 wt% Cu, i.e. the major part of the binary AlAl₂Cu eutectic (0–54 wt% Cu). As well as providing an interesting overview of solidification structures, several features of this map can be used to gain information on the AlCu phase diagram.     

“Causal reasoning” in rats: A reappraisal.

It has recently been argued that rats engage in causal reasoning and they do so in a way that is consistent with Bayes net theories (Blaisdell, Sawa, Leising & Waldmann, 2006). This argument was based upon the finding that the tendency of cues to elicit approach to a food-well was reduced when their presentation was contingent on lever pressing. There is, however, an alternative interpretation of the critical experimental findings that is based on the simple principle of response competition: wherein lever pressing interferes with the tendency to approach the food well. Here the authors replicated Experiments 1 and 2a of Blaisdell et al. (2006) and found reciprocal patterns of lever pressing and food well approach during the critical cues. These results lend direct support for an interpretation in terms of response competition while providing evidence contrary to Bayes net theories, and are readily interpreted within the theoretical framework provided by traditional associative learning theory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The evolving vocabulary of the social sciences: The case of “socialization”.

While the term “socialization” stands as a common and clearly understood term regularly used in social science and lay conversations alike, its history is complex. In the 19th century, socialization was introduced to refer to societal activities or projects, and only in the early 20th century did it gain usage as a term describing psychological processes transpiring within the individual. The architecture of the newer meaning harbored ambitions and problems of modern social science, including ideals of interdisciplinary theory and theoretic resolution of the individual/society dualism. Nevertheless, socialization became a central object of social scientific inquiry after World War II. This significant social scientific object was repeatedly altered: initially representing a vision of conforming citizens who were free from certain troubling characteristics depicted in psychoanalysis and well-suited to democracy, it later was engaged to create a vision of autonomous, resilient, and cognitively active actors able to negotiate a complex social world. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

The plastic anisotropy of two-phase aluminium alloys—I. Anisotropy in unidirectional deformation

The changes in plastic anisotropy which accompany precipitation from a supersaturated solid solution have been investigated in textured polycrystals of three different aluminium alloys. Plastic behaviour was measured in unidirectional straining by uniaxial tension and by plane strain compression. Plastic anisotropies in the solution treated conditions were well predicted by the Taylor/Bishop and Hill model of polycrystalline plasticity used in conjunction with a series expansion method of treating the crystal orientation distribution. Significant deviations from these predicted anisotropies resulted from the introduction of semi-coherent precipitates, although the textures of the primary phases were unchanged by the ageing treatments. It is shown that changes in plastic anisotropy caused by precipitation can be explained satisfactorily by two different continuum models. The first of these, due to Hosford and Zeisloft, assumes plastic deformation of the second phase. The second model, introduced here, is based essentially on the adaptation of the transformation problem solutions of Eshelby made by Brown and Stobbs: it assumes deformation of the precipitate is elastic. It is concluded that selection of the more appropriate model requires that additional evidence be taken into account For the case of semi-coherent precipitates in the aluminium alloys investigated, the elastic inclusion model is more realistic. However, direct evidence of the magnitude of the internal stresses generated during plastic deformation is required to test some of the assumptions implicit in the simple form of the elastic inclusion model.