Enhancement of piezoelectricity in a mixed ferroelectric

We use first-principles density-functional total energy and polarization calculations to calculate the piezoelectric tensor at zero temperature for both cubic and simple tetragonal ordered supercells of Pb_3GeTe_4. The largest piezoelectric coefficient for the tetragonal configuration is enhanced by a factor of about three with respect to that of the cubic configuration. This can be attributed to both the larger strain-induced motion of cations relative to anions and higher Born effective charges in the tetragonal case. A normal mode decomposition shows that both cation ordering and local relaxation weaken the ferroelectric instability, enhancing piezoelectricity.Comment: 5 pages, revtex, 2 eps figure

The Domination Number of Grids

In this paper, we conclude the calculation of the domination number of all $n\times m$ grid graphs. Indeed, we prove Chang's conjecture saying that for every $16\le n\le m$, $\gamma(G_{n,m})=\lfloor\frac{(n+2)(m+2)}{5}\rfloor -4$.Comment: 12 pages, 4 figure

Bayesian Probabilistic Numerical Methods in Time-Dependent State Estimation for Industrial Hydrocyclone Equipment

The use of high-power industrial equipment, such as large-scale mixing equipment or a hydrocyclone for separation of particles in liquid suspension, demands careful monitoring to ensure correct operation. The fundamental task of state-estimation for the liquid suspension can be posed as a time-evolving inverse problem and solved with Bayesian statistical methods. In this article, we extend Bayesian methods to incorporate statistical models for the error that is incurred in the numerical solution of the physical governing equations. This enables full uncertainty quantification within a principled computation-precision trade-off, in contrast to the over-confident inferences that are obtained when all sources of numerical error are ignored. The method is cast within a sequential Monte Carlo framework and an optimized implementation is provided in Python

Sport prosumer networks: exploring prosumption value in Twitter conversations during COVID-19

Purpose: Value within prosumption systems such as Twitter is underexplored. We adopt an economic sociology perspective to measure prosumption value, using the #ProjectRestart campaign as football looked to resume following COVID-19. Design: We use social network analysis to analyse 21,000 tweets involving 10,810 Twitter users using the #ProjectRestart hashtag. Specifically, we apply network theory measures, community clustering, betweenness, domain prestige and proximity prestige to explore how prosumption value can be measured. Findings: Our empirical findings demonstrate how value can be perceived within prosumption systems. Specifically, it shows how developing cohesive prosumer networks is vital in exploiting prosumer capital, creating value in the virtual space, which is imperative in negotiating through times of uncertainty, like COVID-19. Practical Implications: The practical implications encourage the industry to think of value in the virtual space differently, embedding this into future management strategies. Research Contribution: This research provides a theoretical contribution of prosumer value, blending prosumption and economic sociology theories. Empirically, it demonstrates how actors in the football world used prosumer networks to create value during the COVID-19 pandemic

Football Worlds: Business and networks during COVID-19

The structure of football can also be conceived as a form of ecosystem, or even a social world, constructed through a network of individuals, within a division of labour, that interact under a set of specific conventions. In this commentary we describe that socially constructed world – Football World. The nature of this structural world makes network theory an appealing framework to explore processes of the football ecosystem during COVID-19. While we focus on the English Premier League, notably this league is embedded within a European and international marketplace it offer relevance for the broader global football ecosystem. We proceed to explore this dynamic Football World by considering how the different collectives forms – specifically fans, players and clubs – have been affected by COVID-19. We comment on the potential implications for the connective fabric of the broader network and what these observations mean for potential future research

Diffraction behaviour of three-component fibonacci Ta/Al multilayer films

A class of quasiperiodic structure three-component Fibonacci (3CF) Ta/Al multilayer films is fabricated by dual-target magnetron sputtering. The microstructure of this film is investigated by transmission electron microscopy and electron and X-ray diffraction. Cross-section transmission electron microscopy demonstrates a well formed layer structure of 3CF Ta/Al superlattices. The electron-diffraction satellite spots, which can be indexed by three integers, correspond to the X-ray diffraction peaks in both position and intensity. The scattering vectors observed in electron and X-ray diffraction are in good agreement with the analytical treatment from the projection method

Transmission-electron microscopy study of the shape of buried InxGa1-xAs/GaAs quantum dots

High-resolution electron microscopy, on-zone bright-field imaging, and image simulation were used to investigate the shape of capped In0.06Ga0.4As/GaAs semiconductor quantum dots. Cross-section [110] high-resolution images suggest that the quantum dots are lens shaped, while the [001] on-zone bright-field images show a contrast that suggests a quantum dot morphology with four edges parallel to [100]. The image simulation, however, suggests that a spherical quantum dot can produce a square-shaped image. These observations lead to the conclusion that the quantum dots in buried In0.6Ga0.4As/GaAs semiconductor heterostructures are lens shaped

Developing Digital Content for Teaching in Online and Hybrid Modes of Delivery

Based on a synthesis of various online, distance, and remote teaching literatures, and combined with our own personal experiences of online teaching pre and during Covid-19, we have developed the below “Hybrid Content Model” as a guideline tool for academics planning and developing teaching content for hybrid modes of delivery. The model outlines three core considerations: (1) Design, (2) Socialization, and (3) Learning, Reflection and Development. Each stage has practical implications for the choice and structuring of activities. In our discussion of each section we try to provide support and guidance that can be used across different subject disciplines