A backstepping‐based low‐and‐high gain design for marine vehicles

A backstepping control design for marine vehicles was described in (Marine Control Systems: Guidance, Navigation and Control of Ships, Rigs, and Underwater Vehicles. Marine Cybernetics AS: Trondheim, Norway, 2002). Under a backstepping feedback law, global asymptotic stability of the closed‐loop system can be shown under the assumption of unlimited actuation. This paper addresses the issues that arise in the implementation of a backstepping feedback law by saturating actuators. First, for a given backstepping feedback law, an estimate of the domain of attraction is given for the resulting closed‐loop system under actuator saturation. A high gain component is then constructed and augmented to the original backstepping feedback law. This additional high gain component is shown not to shrink the estimate of the domain of attraction but to possess the ability to improve the closed‐loop response and to reject disturbance. Copyright © 2008 John Wiley & Sons, Ltd.     

Böhler Edelstahl

Böhler Edelstahl produces high performance tool and high speed steels via an optimised powder metallurgy/hot isostatic pressing route, as part of a high value special alloys portfolio.     

Assessment of the fire toxicity of building insulation materials

A significant element in the cost of a new building is devoted to fire safety. Energy efficiency drives the replacement of traditional building materials with lightweight insulation materials, which, if flammable can contribute to the fire load. Most fire deaths arise from inhalation of toxic gases. The fire toxicity of six insulation materials (glass wool, stone wool, expanded polystyrene foam, phenolic foam, polyurethane foam and polyisocyanurate foam) was investigated under a range of fire conditions. Two of the materials, stone wool and glass wool failed to ignite and gave consistently low yields of all of the toxic products. The toxicities of the effluents, showing the contribution of individual toxic components, are compared using the fractional effective dose (FED) model and LC₅₀ (the mass required per unit volume to generate a lethal atmosphere under specified conditions). For polyisocyanurate and polyurethane foam this shows a significant contribution from hydrogen cyanide resulting in doubling of the overall toxicity, as the fire condition changes from well-ventilated to under-ventilated. These materials showed an order of increasing fire toxicity, from stone wool (least toxic), glass wool, polystyrene, phenolic, polyurethane to polyisocyanurate foam (most toxic).     

Inventive payoff from R&D in Japanese industry: convergencewith the West

An attempt is made to determine if investment in R&D and the hiring of college-educated employees result in a higher rate of inventions. The relationship between the input of R&D and inventive output is studied in two samples of Japanese factories, 34 in 1982 and 44 in 1970. These results are compared with findings in a parallel American study. The correlations between R&D and inventive output are similar in Japan and America in the 1980s, despite some differences in the management of innovation in the two nations. Moreover, the most Westernized subsample of Japanese firms in the 1970s had correlations between R&D and invention similar to those observed in the American study. Thus, it is concluded that some degree of convergence may be taking place in R&D management strategies in the two nations     

Sensory modality, temperament, and the development of sustained attention: A vigilance study in children and adults.

Applying optimal stimulation theory, the present study explored the development of sustained attention as a dynamic process. It examined the interaction of modality and temperament over time in children and adults. Second-grade children and college-aged adults performed auditory and visual vigilance tasks. Using the Carey temperament questionnaires (S. C. McDevitt & W. B. Carey, 1995), the authors classified participants according to temperament composites of reactivity and task orientation. In a preliminary study, tasks were equated across age and modality using d= matching procedures. In the main experiment, 48 children and 48 adults performed these calibrated tasks. The auditory task proved more difficult for both children and adults. Intermodal relations changed with age: Performance across modality was significantly correlated for children but not for adults. Although temperament did not significantly predict performance in adults, it did for children. The temperament effects observed in children-specifically in those with the composite of reactivity-occurred in connection with the auditory task and in a manner consistent with theoretical predictions derived from optimal stimulation theory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Diffusion of aqueous hydrochloric acid into polyester resins

The influence of an applied stress on the solubility and diffusivity of aqueous hydrochloric acid in polyester resins has been examined. A radioactive tracer method, involving the use of³H and³⁶Cl, enabled the mobility of both the water and the acid in the solution to be followed simultaneously. The results obtained were in accordance with those obtained previously with unstressed resins and showed that whereas water would diffuse freely in stressed polymers, hydrochloric acid would not. The results have important implications in relation to the mechanism of crack propagation in E-glass/polyester composites.     

Combustion and thermal properties of OctaTMA-POSS/PS composites

Inorganic–organic composites of octa(tetramethylammonium) polyhedral oligomeric silsesquioxanes (OctaTMA-POSS) and polystyrene (PS) were prepared by melt-mixing method. The composites were characterized by Fourier-transform infrared spectrometry (FT-IR), Transmission electronic microscopy (TEM), scanning electronic microscopy (SEM), and thermal gravimetric analysis (TGA). Their flammability was evaluated by cone calorimeter test. The experimental results indicate that OctaTMA-POSS, when present in low ratios (1%–5%, weight ratio) in the composites, can decrease the peak heat release rate (HRR) by 15%, while high ratios of OctaTMA-POSS (20% and 30%) can decrease the peak HRR and the average HRR approximately linearly. Concentration and release rate of carbon monoxide (CO) in the composites combustion are also decreased evidently. Thermal gravimetric analysis under nitrogen and air atmosphere both show that the char yield increases obviously. These advances are attributed to the special properties of OctaTMA-POSS and its dispersion in PS.