Compression mechanical properties of wood at temperatures simulating fire conditions

Compression mechanical properties of wood at temperatures simulating fire conditions have been obtained for use in structural response models to aid the design of light-timber framed walls as fire barriers in accordance with recent performance-based fire codes. The properties that have been measured are elastic modulus and strength. The properties were obtained from samples that had a number of similarities to studs in walls. The effects of knots, however, have been excluded from this study. The elastic modulus greatly reduces as temperatures approach the vaporization point of moisture. The properties were significantly lower compared with properties given in the literature. Input of the measured properties into a structural fire model for walls led to good comparisons with results of experiments on walls with low load ratios (that is, the ratio of the applied load to the collapse load capacity at ambient conditions). Such walls are typically used in building construction. However, the elastic moduli presented in this paper and in other literature do not lead to good model predictions for slender walls with high load ratios. Further research into creep is required. Copyright © 2001 John Wiley & Sons, Ltd.     

Focusing qualitative simulation using temporal logic: theoretical foundations

We illustrate TeQsim, a qualitative simulator for continuous dynamical systems that combines the expressive power of qualitative differential equations with temporal logic to constrain and refine the resulting predicted behaviors. Temporal logic is used to specify constraints that restrict the simulation to a region of the state space and to specify trajectories for input variables. A propositional linear‐time temporal logic is adopted, which is extended to a three valued logic that allows a formula to be conditionally entailed when quantitative information specified in the formula can be applied to a behavior to refine it. We present a formalization of the logic with correctness and completeness results for the adopted model checking algorithm. We show an example of the simulation of a non‐autonomous dynamical system and illustrate possible application tasks, ranging from simulation to monitoring and control of continuous dynamical systems, where TeQsim can be applied. This revised version was published online in June 2006 with corrections to the Cover Date.     

Age trends in the development of aggression, sex typing, and related television habits.

Conducted a 3-yr longitudinal study with 2 large samples of elementary school youngsters overlapping in 1 grade (N?=?672, 607, and 505 for each successive year). It was thus possible to trace developmental trends from Grades 1 to 5 on the following variables: aggression, frequency of TV viewing, extent of violence viewed on TV, judged realism of TV programs, and preference for masculine, feminine, or neutral activities. Data support the theory that there is a sensitive period during which the effect of TV can be especially influential on children's behavior. Further, since the correlation between violence viewing and aggression tends to increase until age 10–21 yrs, a cumulative effect beyond the sensitive period is suggested. (11 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An application of artificial intelligence to the choreography of dance

This paper describes an experimental computer program that applies the techniques of artificial intelligence to the creation of dance. Specifically, a user expresses a set of dance rules (in a special English-like rule language) which describes some of the dynamic aspects of a dance. These rules are applied nondeterministically by a rule driver program. The rules themselves are similar to those that form the knowledge base of expert systems. The rule driver embodies a heuristic algorithm of the type found in many artificial intelligence programs.James H. Bradford is an Associate Professor of Computer Science at Brock University. He is an active researcher in the area of Human/Computer Interaction with particular interests in the analysis of speech and the representation of dance.Paulette Côté-Laurence is an Associate Professor of Physical Education at Brock University. Her research interests are in the areas of motor control and the acquisition of dance skills, psychology of rhythm, and dance technology.     

Cognitive processing of trauma cues in adults reporting repressed, recovered, or continuous memories of childhood sexual abuse.

Psychologically traumatized people exhibit delayed color naming of trauma words in the emotional Stroop task. Four groups of participants were asked to color name positive words, neutral words, and trauma words; these groups included 15 women who believed that they harbored repressed memories of childhood sexual abuse (CSA), 13 women who reported recovered memories of CSA, 15 women who had never forgotten their CSA, and 12 women who had never been abused. Repressed-memory participants exhibited patterns of interference indistinguishable from those of the nonabused control group participants. Irrespective of group membership, the severity of self-reported posttraumatic stress disorder symptoms was the only significant predictor of trauma-related interference, r(48)?=?.30?, p?     

Multiscale modeling of polymer materials using a statistics-based micromechanics approach

A large number of possible polymer chain conformations exist for a given volume of an amorphous polymer. The prediction of elastic properties of a polymer must therefore consider more than a single combination of chain conformations. A multiscale modeling approach is proposed to predict the bulk elastic properties of polymer materials using a series of molecular models of individual polymer microstates and a statistics-based micromechanical modeling method. The method is applied to polyimide and polycarbonate systems. It is shown that individual microstates can yield a wide range of predicted elastic properties, whereas the consideration of multiple microstates yield predicted properties that agree more closely with experimentally determined values of Young’s modulus. Additionally, the upper and lower limits of possible elastic constants are also established based on the consideration of multiple microstates.     

Full scale experiments for evaluating theoretical fire wall models

The aim of the research described in this paper was to provide experimental results for the evaluation of theoretical models for predicting the behaviour and time‐to‐failure of loadbearing and non‐loadbearing wood framed walls in fire. References for thermal and mechanical properties of wood and gypsum board are given to provide comprehensive input for the evaluation of theoretical wall models. The scope of the research involved full‐scale uninsulated cavity walls with well‐controlled clearly known conditions including initial ambient vertical load capacity for benchmarking the reduction in capacity and stiffness, rotational stiffness of supports, eccentricity of vertical load, elastic moduli of wood and gypsum board in compression, stiffness of slip between gypsum board and studs and end stud effects. The experiments were repeated and they demonstrated that the controls led to high consistency in the results despite the inherent large variability of the mechanical properties of wood. The results include temperature distributions, initial vertical load capacity, load‐deflection plots and times‐to‐failure. The results show that the temperatures in the studs are approximately uniform until all the moisture is vaporized. Thermal properties of wood will not vary significantly for consistent density, moisture content and species of wood. The main structural actions that should be modelled for different loading regimes are deduced. Copyright © 2004 John Wiley & Sons, Ltd.     

Age and skill in visual search.

The effects of age and experience on visual-cognitive performance were examined by administering a domain-relevant visual search task and a standard letter search task to skilled and control Ss at 2 age levels (young and middle-aged adults). In the skilled task, Ss searched for a designated item within 3-item displays using images of bacteria morphology as targets and distractors. Each target was preceded by a word prime representative of bacteria morphology that was valid, invalid, or neutral with respect to the diagnostic characteristics of the target. Skilled Ss showed an age deficit in letter search performance, but the performance of the young and middle-aged skilled Ss was not different on the domain-relevant task. Valid primes produced benefits for the young and middle-aged skilled participants, whereas control Ss were unaffected by the prime manipulation. Results were consistent with the prediction that experience serves to attenuate age-related declines in visual-cognitive performance in the skilled domain. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Etude, par voie electrochimique, de l''influence du fer (II) sur la reduction de cetones en solution dans le N, N-dimethylformamide (DMF)

The electrochemical reduction, in DMF, of a series of aromatic ketones has been studied in the presence of iron salts. With these ketones, the first reduction peak of the ketone is always preceeded by another peak which appears at a less negative potential. This peak is attributed to a fast chemical reaction between Fe(II) and the anion radical of the ketone, which shifts the electrochemical peak potential. With fluorenone, several species are formed corresponding to 1/1, 3/4, 1/2, 1/4 iron/ketone ratios. For the other ketones, the 1/1 species is mainly formed.