The reduction of uncertainty concerning future pain.

Ss received series of electric shocks to the forearm in which the temporal schedule and the sequence of shock intensities were associated with varying levels of randomness or uncertainty. The Ss were permitted an instrumental response which produced, in advance, information concerning 1 or both of these aspects of the shocks. Such information functioned as a strong positive reinforcement for most Ss. Instrumental response rate was a significant increasing function of the degree of uncertainty associated with the shock series, and occurred significantly more often for information concerning the temporal occurrence of shock than for its intensity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A review on the performance of Savonius wind turbines

This paper presents a review on the performance of Savonius wind turbines. This type of turbine is unusual and its application for obtaining useful energy from air stream is an alternative to the use of conventional wind turbines. Simple construction, high start up and full operation moment, wind acceptance from any direction, low noise and angular velocity in operation, reducing wear on moving parts, are some advantages of using this type of machine. Over the years, numerous adaptations for this device were proposed. The variety of possible configurations of the rotor is another advantage in using such machine. Each different arrangement of Savonius rotor affects its performance. Savonius rotor performance is affected by operational conditions, geometric and air flow parameters. The range of reported values for maximum averaged power coefficient includes values around 0.05–0.30 for most settings. Performance gains of up to 50% for tip speed ratio of maximum averaged power coefficient are also reported with the use of stators. Present article aims to gather relevant information about Savonius turbines, bringing a discussion about their performance. It is intended to provide useful knowledge for future studies.     

Fuzzy rough set techniques for uncertainty processing in a relational database

This paper concerns the modeling of imprecision, vagueness, and uncertainty in databases through an extension of the relational model of data: the fuzzy rough relational database, an approach which uses both fuzzy set and rough set theories for knowledge representation of imprecise data in a relational database model. The fuzzy rough relational database is formally defined, along with a fuzzy rough relational algebra for querying. Comparisons of theoretical properties of operators in this model with those in the standard relational model are discussed. An example application is used to illustrate other aspects of this model, including a fuzzy entity–relationship type diagram for database design, a fuzzy rough data definition language, and an SQL‐like query language supportive of the fuzzy rough relational database model. This example also illustrates the ease of use of the fuzzy rough relational database, which often produces results that are better than those of conventional databases since it more accurately models the uncertainty of real‐world enterprises than do conventional databases through the use of indiscernibility and fuzzy membership values. ©2000 John Wiley & Sons, Inc.     

Degradation of cellulosic and hemicellulosic substrates using a chelator‐mediated Fenton reaction

The involvement of catechol and hydroxamate chelators, along with hydrogen peroxide and Fe³⁺, in the degradation of cellulosic and hemicellulosic substrates was examined with the purpose of improving our current knowledge of the non‐enzymatic mechanisms involved in wood biodegradation by fungi. It could be demonstrated that a catechol chelator‐mediated Fenton reaction not only clearly degraded hemicellulosic substrates but also significantly accelerated and increased the effectiveness of degradation reactions. On the other hand, when a hydroxamate chelator‐mediated Fenton reaction was used, an inhibitory effect was observed. When cellulosic substrates underwent a chelator‐mediated Fenton reaction, no significant difference in degradation was observed between catechol and hydroxamate chelator‐mediated reactions. However, a catechol‐mediated reaction did accelerate the degradation of cellulosic substrates at the beginning of reactions. In addition, it was observed that with a chelator‐mediated Fenton reaction, oxidation of cellulose proceeds depolymerization. Copyright © 2005 Society of Chemical Industry     

Dynamic buckling of thin isotropic plates subjected to in-plane impact

The dynamic stability behaviour of imperfect simply supported plates subjected to in-plane pulse loading is investigated. For the calculation of dynamic buckling loads a stress failure criterion is applied. The large-deflection plate equations are solved by a Galerkin method by using Navier's double Fourier series. In this paper the dynamic load factor (DLF) is redefined and plots that are useful for the design of plate structures are presented. Parametric studies are performed in which the influences of the pulse duration, shock function, imperfection, geometric dimensions and limit stress of the material are discussed. Comparison between the dynamic buckling loads, which are obtained by the commonly used criterion of Budiansky and Hutchinson [Proceedings of the 11th International Congress of Applied Mechanics (1964) 636], and the dynamic elastic limit loads, which are computed by the stress failure criterion, shows that the latter criterion is more useful for the design of lightweight structures.     

Tubular dentin sealer penetration after different final irrigation protocols: A confocal laser scanning microscopy study

The aim of this study was to evaluate tubular dentin sealer penetration, comparing different final irrigation protocols using a conventional needle (CONV), EndoActivator system (EAS), EndoVac system (EVS), and ultrasound (PUI). Initially, fifty‐two first maxillary molars with a single canal in the palatal root, without abrupt curvatures, resorptive processes, or previous endodontic treatment were selected for this study. Then, the crowns were sectioned to obtain palatal roots 15 mm in length. The root canals were prepared with the ProTaper Universal System and irrigated with 5% NaOCl. Afterwards, the specimens were divided into four groups (n. 13), according to the final irrigation protocol: CONV, EAS, EVS, and PUI. After filling, slices at 3 mm and 5 mm from the apex were obtained for analysis by confocal laser scanning microscopy. Two‐way comparisons between the groups and the levels were performed with Games Howell's test (p < .05). Tubular dentin sealer penetration was higher at 5 mm compared with 3 mm from the apex (p < .05). The EAS group showed a higher percentage of tubular dentin sealer penetration, compared with the CONV group, at both levels. At 3 mm, there was no statistically significant difference among EAS, EVS, and PUI; however, these groups showed better performance, compared with the CONV group. At 5 mm, there was no statistically significant difference between the EAS and EVS groups, but both showed higher sealer penetration than the PUI group (p < .05). The EAS and EVS groups achieved better degrees of tubular dentin sealer penetration, compared with the other groups.     

Effective Thermal-Conductivity Measurements on Supporting Structures of the Mercury Probe Bepi Colombo

Measurements were done on a carbon fiber reinforced composite (CFC) sample tested for the space probe Bepi Colombo by using the guarded hot-plate (GHP) method. The values of interest were the thermal transmittance through the samples, (56.3 ± 3.6) W · m^?2 · K^?1, and the effective thermal conductivity (1.06 ± 0.07) W · m^?1 · K^?1. The samples consist of a light honeycomb core attached to thicker surface plates. Due to this construction, the effective thermal conductivity parallel to the face plates is higher than the effective thermal conductivity through the sample. This leads to lateral heat gains or losses during the GHP measurement, which in return can lead to erroneous results. Furthermore, due to the high rigidity of the CFC material, there will be high contact resistances between the samples and the GHP apparatus plates. The separation of these thermal contact resistances from the total measured thermal resistance is essential in order to achieve correct results. Good results were achieved using a special measurement setup and a lateral correction method designed to reduce errors due to lateral heat flows.     

On the fracture behaviour of thin-walled SFRC roof elements

The paper presents an experimental and a numerical investigation on precast, prestressed reinforced concrete (RC) and steel fibre reinforced concrete (SFRC) roof elements. The element investigated has a complex geometry, because it is characterized by a thin-walled open cross-section and a long span. In order to reduce the total weight of the traditional RC element and favour an industrialized production process, the structure can be made of fibre reinforced concrete. This composite presents a significant toughness after cracking that can substitute the diffused reinforcement made of common steel-welded meshes, conserving the longitudinal prestressed reinforcement. The mechanical characterization of SFRC material has found recently a shared design approach that starts with the identification of the uniaxial tension constitutive law obtained from a standardized bent notched specimen. Nevertheless, for defined casting procedures of the structure, like in prefabrication, the identification of the uniaxial tension constitutive law can be performed by a four point bending tests on suitable unnotched specimens, able to take into account the effective fibre orientation in the structure and the real nominal thickness of the critical portion of the element. The latter two different experimental test procedures (on notched or unnotched specimens) lead to significant differences in the tension softening response. For this reason SFRC tension softening relations, coming from the previously mentioned experimental tests, are analyzed in this paper in order to evaluate their effects on the structural response of this large-scale roof element. The results of the experimental tests on the roof element presented in this paper show that second-order effects drastically anticipated the achievement of the longitudinal bending moment resistance calculated following the beam theory and neglecting transverse equilibrium and in-plane cross section deformation. Two numerical models are proposed in this paper to evaluate second-order effects in the resistance assessment of the precast structure. The first one is based on a plane section approach (PSA), while the second one is based on a non-linear finite element analysis (NLFEA). Both second-order effect and uniaxial tension constitutive relationship roles are examined in relation to the global response of the structure up to failure. The final remarks, coming from a careful comparison between experimental and numerical results, highlight that the failure is mainly led by a structural behaviour, because second-order effects prevail on non-linear response of SFRC materials adopted.