A two-platform task reveals a deficit in the ability of rats to return to the start location in the water maze.

The ability of rats to return to the start location was examined with a 4-arm radial water maze. The task required rats to find 2 hidden platforms in sequence. Rats were released from 1 of 3 arms and there was a platform located in the fourth arm. Once a rat found this platform, a 2nd platform was raised in another location, which was either the start location, for 1 group, or another fixed location, for a control group. Across 3 experiments, all rats learned the location of the 1st fixed platform in 80 to 120 trials. However, rats had difficulty finding a 2nd platform if it was at the start location. Control groups revealed that rats could learn 2 platform locations and that the difficulty in learning to return to the start location did not seem to be attributable to its aversive nature. In separate groups, exposure to the start location was increased by starting the rats from an initially stable platform. Rats still did not readily learn to return to the start location. The authors suggest that start location, when varied, cannot readily be used to define the location of a hidden platform. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Numerical Modeling of Bolted Lap Joint Behavior

Nonlinear finite-element models are developed that predict the load-elongation behavior of conical-head bolted lap joints, and the load-elongation predictions are compared with experimental test data. The study is conducted for several panel thicknesses with three fastener sizes and three panel materials. The model load-elongation predictions are in excellent agreement with experimental test data. Model parameters, such as part discretization, material model selection, sliding interface friction coefficients, and convergence tolerances, are discussed. A means of inducing clamp in the joint is also developed. The results show that nonlinear finite-element analysis may reliably predict the behavior of conical-head bolted joints.     

Fracture mechanics models applied to delayed failure of LVL beams

Several theories for modelling fracture and slow growth of a crack in wood have been developed. The various models may be differentiated by the specifically regarded stress levels, failure mechanisms and averaging procedures. This paper deals with the application of viscoelastic fracture mechanics models to predict delayed failure of a timber element in bending. Simulations are compared to experimental results of bending tests carried out on LVL (Laminated Veneer Lumber) notched beams. This analysis emphasizes the influence of the geometry and of the size of the beam as well as of the damage area on the delayed failure.     

Metamemory judgments of the origin and content of course information: Comparing text and lecture materials.

The accuracy and relations between students' specific and general knowledge of content and origin were examined. Students answered multiple-choice questions derived from the text, lecture, or both sources, decided whether each question originated from one of these sources or from their own conclusions, decided whether they had lecture information in their notes, and rated their confidence in these judgments. The three types of questions were equally difficult to answer but were significantly different in the accuracy and confidence of origin judgments, and confidence in the answers' correctness. Students' origin judgments were equivalent when they correctly and incorrectly answered questions. Students who knew fewer correct answers tended to be more confused about the origin of their knowledge. The dissociation between origin and content knowledge is discussed within M. K. Johnson and C. L. Raye's (see record 1981-06694-001) reality-monitoring model, with emphasis on the inference and retrieval processes involved in judging the origin of one's knowledge. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Robustness of a Spline Element Method with Constraints

The spline element method with constraints is a discretization method where the unknowns are expanded as polynomials on each element and Lagrange multipliers are used to enforce the interelement conditions, the boundary conditions and the constraints in numerical solution of partial differential equations. Spaces of piecewise polynomials with global smoothness conditions are known as multivariate splines and have been extensively studied using the Bernstein-Bézier representation of polynomials. It is used here to write the constraints mentioned above as linear equations. In this paper, we illustrate the robustness of this approach on two singular perturbation problems, a fourth order problem and a Stokes-Darcy flow. It is shown that the method converges uniformly in the perturbation parameter.     

STUDY AND MODELLING OF COATED CAR PAINTING FILM BY INFRARED OR CONVECTIVE DRYING

In this study, we described and modelled some coupled material transformations with heat and mass transfer phenomena which occur during the convective or the infrared drying of coated films of model car paintings. For these very complex reactive systems -highly shrinking, hygroscopic, semi-transparent (infrared)- the vaporization process is coupled with the polymerization reaction itself which determines significantly the material properties of the dry paint coating. Three model systems (paint + support) were successively defined and investigated by association of five supports of different radiative or adhesive properties -polish aluminium, blackened aluminium, glass, galvanized iron and composite plastic (SMC)- with three model paintings : epoxy-amine system, polyurethane system and polyvinylalcohol (PVA). Two laboratory combined dryers (convective or infrared) were set up in order to control and regulate precisely the main process parameters: aerothermic conditions (temperature and velocity), spectrum (NIR or MIR) and flux density of infrared radiation.

Firstly, the kinetics of the polymerization were followed all along the process by three different techniques : DSC (Differential Scanning Calorimetry), SEC (Size Exclusion Chromatography), FT-ERS (FOURIER Transform Infrared Spectroscopy). The glass transition temperature of the material during the drying process was deduced from DSC data with the fractional conversion of the monomer. These two parameters were well correlated by the DI BENEDETTO'S relationship, thus defining some characteristic curve of the painting system. Drying curves -temperature profiles and drying rates- were determined for PVA systems for many operating conditions, principally infrared flux density, spectra type or air velocity. The two main coating properties necessary for the modeling were deduced from drying experiments 1: the mean radiative absorptivity as a function of the mean moisture content, 2: the water apparent mass diffusivity as a function of the temperature and of the local moisture content. A diffusive model - written with a mobile frame of coordinates (lagrangian coordinates)- associated with an overall heat balance of the support + coating system, has proved capable of predecting very well the drying curves and the temperatures profiles So, this whole set of results -associated with other material properties (rheological, adhesive, color, etc ⃛)- will be useful to rationally optimize the industrial dryers operating in the car manufactories.     

Provision and maintenance of presence and immersion in hand‐held virtual reality through motion based interaction

Hand‐held devices are also becoming computationally more powerful and being equipped with special sensors and non‐traditional displays for diverse applications aside from just making phone calls. As such, it raises the question of whether realizing virtual reality, providing a minimum level of immersion and presence, might be possible on a hand‐held device capable of only relatively “small” display. In this paper, we propose that motion based interaction can widen the perceived field of view (FOV) more than the actual physical FOV, and in turn, increase the sense of presence and immersion up to a level comparable to that of a desktop or projection display based VR systems. We have implemented a prototype hand‐held VR platform and conducted two experiments to verify our hypothesis. Our experimental study has revealed that when a motion based interaction was used, the FOV perceived by the user for the small hand held device was significantly greater than (around 50%) the actual. Other larger display platforms using the conventional button or mouse/keyboard interface did not exhibit such a phenomenon. In addition, the level of user felt presence in the hand‐held platform was higher than or comparable to those in VR platforms with larger displays. We hypothesize that this phenomenon is related to and analogous to the way the human vision system compensates for differences in acuity resolution in the eye/retina through the saccadic activity. The paper demonstrates the distinct possibility of realizing reasonable virtual reality even with devices with a small visual FOV and limited processing power. Copyright © 2010 John Wiley & Sons, Ltd.