National Physical Laboratory

About: National Physical Laboratory is a facility organization based out in London, United Kingdom. It is known for research contribution in the topics: Dielectric & Thin film. The organization has 7615 authors who have published 13327 publications receiving 319381 citations.

Wolf search algorithm with ephemeral memory

Abstract: In computer science, a computational challenge exists in finding a globally optimized solution from a tremendously large search space. Heuristic optimization methods have therefore been created that can search the very large spaces of candidate solutions. These methods have been extensively studied in the past, and progressively extended in order to suit a wide range of optimization problems. Researchers recently have invented a collection of heuristic optimization methods inspired by the movements of animals and insects (e.g., Firefly, Cuckoos, Bats and Accelerated PSO) with the advantages of efficient computation and easy implementation. This paper proposes a new bio-inspired heuristic optimization algorithm called the Wolf Search Algorithm (WSA) that imitates the way wolves search for food and survive by avoiding their enemies. The contribution of the paper is twofold: 1. for verifying the efficacy of the WSA the algorithm is tested quantitatively and compared to other heuristic algorithms under a range of popular non-convex functions used as performance test problems for optimization algorithms; 2. The WSA is investigated with respective to its memory requirement. Superior results are observed in most tests.

Uncertainty of complex permittivity measurements by split-post dielectric resonator technique

Abstract: Split-post dielectric resonators operating at frequencies 1.4–5.5 GHz were used to measure complex permittivity of single crystal standard reference dielectric materials with well known dielectric properties previously measured by other techniques. Detailed error analysis of permittivity and dielectric loss tangent measurements has been performed. It was proved both theoretically and experimentally that using split post resonators it is possible to measure permittivity with uncertainty about 0.3% and dielectric loss tangent with resolution 2×10 −5 for well-machined laminar specimens.

Design Data for Engineering Ceramics: A Review of the Flexure Test

Abstract: The uniaxial strength of engineering ceramics is often measured by the well-known flexure strength test method there is a risk that flexure data are not representative of the properties of fabricated components. Reliability estimates for components based upon statistical extrapolation techniques from flexure data may not be valid. This paper reviews the problem and judges the usefulness of flexure data for design purposes. It is shown that some of the limitations of flexure data apply; to other modes of testing, including direct tension testing

Peptide self-assembly for nanomaterials: the old new kid on the block

Abstract: Peptide self-assembly is an increasingly attractive tool for nanomaterials. Perfected in biology peptide self-assembling systems have impacted on nearly any conceivable nanomaterial type. However, with all the information available to us commercialisation of peptide materials remains in its infancy. In an attempt to better understand the reasons behind this shortcoming we categorise peptide self-assembled materials in relation to their non-peptide counterparts. A particular emphasis is placed on the versatility of peptide self-assembly in terms of modularity, responsiveness and functional diversity, which enables direct comparisons with more traditional material chemistries.