Brunel University London

About: Brunel University London is a education organization based out in London, United Kingdom. It is known for research contribution in the topics: Large Hadron Collider & Population. The organization has 10918 authors who have published 29515 publications receiving 893330 citations. The organization is also known as: Brunel & University of Brunel.

Microstructural development of Al-15wt.%Mg2Si in situ composite with mischmetal addition

Abstract: In situ Al-Mg2Si composites, as a new class of ultralight materials for aerospace and other advanced engineering applications, are attracting more and more attention of both material scientists and design engineers. It has been demonstrated in our previous work that with proper microstructural control, in situ Al-Mg2Si composites can offer very promising combinations of strength, ductility and fracture toughness. In the present work, the effects of mischmetal (MM, a mixture of rare-earth, RE elements) additions on the microstructural development of an in situ Al-15wt.%Mg2Si composite were investigated. It was found that with increasing MM additions in the composites. the size of primary Mg2Si particles was considerably reduced, and that the pseudo-eutectic Mg2Si was changed from a fibrous morphology to a flake-like morphology, showing a divorced character. A small amount of RE-containing compounds in the form of Al11RE3 were formed as a result of MM additions. It is believed that MM additions have a strong influence on the nucleation process of primary Mg2Si particles and the subsequent formation of the alpha-Al phase and the pseudo-eutectic matrix. (C) 2000 Elsevier Science S.A. All rights reserved.

Quantized $H_{\infty }$ Control for Nonlinear Stochastic Time-Delay Systems With Missing Measurements

Abstract: In this paper, the quantized H∞ control problem is investigated for a class of nonlinear stochastic time-delay network-based systems with probabilistic data missing. A nonlinear stochastic system with state delays is employed to model the networked control systems where the measured output and the input signals are quantized by two logarithmic quantizers, respectively. Moreover, the data missing phenomena are modeled by introducing a diagonal matrix composed of Bernoulli distributed stochastic variables taking values of 1 and 0, which describes that the data from different sensors may be lost with different missing probabilities. Subsequently, a sufficient condition is first derived in virtue of the method of sector-bounded uncertainties, which guarantees that the closed-loop system is stochastically stable and the controlled output satisfies H∞ performance constraint for all nonzero exogenous disturbances under the zero-initial condition. Then, the sufficient condition is decoupled into some inequalities for the convenience of practical verification. Based on that, quantized H∞ controllers are designed successfully for some special classes of nonlinear stochastic time-delay systems by using Matlab linear matrix inequality toolbox. Finally, a numerical simulation example is exploited to show the effectiveness and applicability of the results derived.

Assessing the carcinogenic potential of low-dose exposures to chemical mixtures in the environment: The challenge ahead

Abstract: Lifestyle factors are responsible for a considerable portion of cancer incidence worldwide, but credible estimates from the World Health Organization and the International Agency for Research on Cancer (IARC) suggest that the fraction of cancers attributable to toxic environmental exposures is between 7% and 19%. To explore the hypothesis that low-dose exposures to mixtures of chemicals in the environment may be combining to contribute to environmental carcinogenesis, we reviewed 11 hallmark phenotypes of cancer, multiple priority target sites for disruption in each area and prototypical chemical disruptors for all targets, this included dose-response characterizations, evidence of low-dose effects and cross-hallmark effects for all targets and chemicals. In total, 85 examples of chemicals were reviewed for actions on key pathways/mechanisms related to carcinogenesis. Only 15% (13/85) were found to have evidence of a dose-response threshold, whereas 59% (50/85) exerted low-dose effects. No dose-response information was found for the remaining 26% (22/85). Our analysis suggests that the cumulative effects of individual (non-carcinogenic) chemicals acting on different pathways, and a variety of related systems, organs, tissues and cells could plausibly conspire to produce carcinogenic synergies. Additional basic research on carcinogenesis and research focused on low-dose effects of chemical mixtures needs to be rigorously pursued before the merits of this hypothesis can be further advanced. However, the structure of the World Health Organization International Programme on Chemical Safety 'Mode of Action' framework should be revisited as it has inherent weaknesses that are not fully aligned with our current understanding of cancer biology.