Distinct order of Gd 4f and Fe 3d moments coexisting in GdFe4Al8

Single crystals of flux-grown tetragonal GdFe4Al8 were characterized by thermodynamic, transport, and x-ray resonant magnetic scattering measurements. In addition to antiferromagnetic order at TN ~ 155 K, two low-temperature transitions at T1 ~ 21 K and T2 ~ 27 K were identified. The Fe moments order at TN with an incommensurate propagation vector (tau,tau,0) with tau varying between 0.06 and 0.14 as a function of temperature, and maintain this order over the entire T<TN range. The Gd 4f moments order below T2 with a ferromagnetic component mainly out of plane. Below T1, the ferromagnetic components are confined to the crystallographic plane. Remarkably, at low temperatures the Fe moments maintain the same modulation as at high temperatures, but the Gd 4f moments apparently do not follow this modulation. The magnetic phase diagrams for fields applied in [110] and [001] direction are presented and possible magnetic structures are discussed.Comment: v2: 14 pages, 12 figures; PRB in prin

Hierarchical Markov normal mixture models with applications to financial asset returns

With the aim of constructing predictive distributions for daily returns, we introduce a new Markov normal mixture model in which the components are themselves normal mixtures. We derive the restrictions on the autocovariances and linear representation of integer powers of the time series in terms of the number of components in the mixture and the roots of the Markov process. We use the model prior predictive distribution to study its implications for some interesting functions of returns. We apply the model to construct predictive distributions of daily S&P500 returns, dollarpound returns, and one- and ten-year bonds. We compare the performance of the model with ARCH and stochastic volatility models using predictive likelihoods. The model's performance is about the same as its competitors for the bond returns, better than its competitors for the S&P 500 returns, and much better for the dollar-pound returns. Validation exercises identify some potential improvements. JEL Classification: C53, G12, C11, C14Asset returns, Bayesian, forecasting, MCMC, mixture models

Selection of electrical accessories: a cost modelling approach

Electrical installations contribute to 6% -10% of the total cost of a typical house. Therefore, the selection of the most appropriate electrical accessories is very important from the client’s point of view. But lack of information about the products and prices makes these decisions very difficult for clients to make. Development of a product-cost model for the selection of electrical accessories could be seen as one of the solutions for this problem. Thus the authors have developed a product-cost model for the selection of electrical accessories for housing constructions in Sri Lanka. A market survey and a series of interviews were conducted in order to collect cost and product data pertaining to electrical accessories used in Sri Lankan domestic electrical installations. All the accessories identified were classified into five main categories based on their functionality. In the data analysis, three main cost categories were identified. On the other hand, three different designs were selected to represent the collection of accessories in a typical domestic electrical installation. Finally, a simple decision support system was developed as the front end for the developed product-cost model

Reinventar o futuro em sintonia com a identidade : traçado de uma ecovia que potencie os patrimónios natural e cultural dos terceirenses

Dissertação de Mestrado, Gestão e Conservação da Natureza, 14 de outubro de 2019, Universidade dos Açores.A ilha Terceira, sendo uma ilha do arquipélago dos Açores, com cerca de 400 km2, torna possível e fácil a deslocação das pessoas de bicicleta, diminuindo o impacto dos combustíveis fósseis. Como a velocidade atingida é inferior à de um carro, é possível apreciar a natureza omnipresente sem lhe causar grande impacto. O acentuado crescimento de um turismo de natureza nas ilhas vem, a par do incremento de estilos de vida saudáveis junto dos residentes, reforçar a necessidade de criar condições para que as pessoas possam usufruir deste meio de transporte alternativo, desfrutando em segurança dos recursos paisagísticos existentes. É, neste sentido, que surge a ideia de criar uma ecovia. A sua implementação exige, todavia, que seja ponderado um conjunto de vertentes tão distintas quanto: as questões climáticas e orográficas do terreno, os recursos naturais e culturais, o ordenamento do território, as infraestruturas existentes, entre outras. Para a escolha do traçado, que melhor valorize estas caraterísticas, foi necessário recorrer a um conjunto de informações indagadas pela investigadora e ao saber especializado e processado de peritos, através de entrevistas, que sustentaram posições muito distintas sobre esta questão. A informação recolhida foi projetada em diferentes mapas, através dos SIG, possibilitando o traçado de diferentes cenários possíveis, dividido em vários troços, que delimitaram as áreas com maior aptidão para implementação de uma ecovia na Ilha Terceira. Desta forma, a metodologia adotada assumiu um caráter multidisciplinar, desenvolvida em três momentos distintos: no tratamento de recolha de dados, no processo de análise de dados e na apresentação e discussão dos resultados obtidos da 1ª proposta do traçado edafoclimático e da 2ª proposta do traçado com a valorização dos patrimónios naturais e histórico-culturais da ecovia, bem como a apresentação das conclusões. A proposta do traçado final é a mais confiável para a implementação de uma ecovia na Ilha Terceira, pois resultou de uma metodologia diversificada e robusta, que emergiu do conhecimento de profissionais, recolhido e testado através de métodos e ferramentas, tornando-se crucial para estar à altura do dinamismo exigido por este projeto.ABSTRACT: Terceira Island is in Azores archipelago. This Island has 400km2 what permits people cycling all the day, reducing the consumption of fossil fuels. The speed is lower than a car, so it is possible to enjoy and appreciate all landscapes, with no direct impact. The strong growth of nature tourism in all islands combined with the healthy lifestyle of population have created the need to join conditions for people cycling securely and enjoying the peaceful and charming landscapes. This is why the idea of creating a Greenway emerges. However, its implementation requires a deep analysis of distinct areas, such as: climate and topography issues in the ground, natural and cultural resources, territorial planning, and infrastructures, among others. To choose the best track, the researcher gathered data combined with expert’s knowledge through structured interviews which supported very distinct positions about this subject. The collected data was processed in SIG’s maps, allowing the creation of numerous tracks, divided into different sections, which delimited regions with more ability to the Greenway’s implementation, in Terceira Island. Thus, the adopted methodology led a multidisciplinary dimension, developed in three moments: data cleaning/analysis, data handling and present/discuss the conclusion and obtained results in the 1st edaphic track proposal and in the 2nd track proposal with the valorisation of the natural, cultural and historical heritage. The final track proposal is the most trusted to implement the Greenway in Terceira, due it’s resulted from a straight application of the strong and appropriate methodology, which emerged of expert’s knowledge and tested using methods and tools. This proposal is the key to match this project’s dynamism

Directed Explicit Model Checking with HSF-SPIN

We present the explicit state model checker HSF-SPIN which is based on the model checker SPIN and its Promela modeling language. HSF-SPIN incorporates directed search algorithms for checking safety and a large class of LTL-specified liveness properties. We start off from the A* algorithm and define heuristics to accelerate the search into the direction of a specified failure situation. Next we propose an improved nested depth-first search algorithm that exploits the structure of Promela Never-Claims. As a result of both improvements, counterexamples will be shorter and the explored part of the state space will be smaller than with classical approaches, allowing to analyze larger state spaces. We evaluate the impact of the new heuristics and algorithms on a set of protocol models, some of which are real-world industrial protocols

Unconventional domain wall magnetoresistance of patterned Ni/Nb bilayer structures below superconducting transition temperature of Nb

Scattering of spin-up and spin-down electrons while passing through a ferromagnetic domain wall leads to an additional resistance for transport current, usually observed prominently in constricted magnetic structures. In this report, we use the resistance of the domain wall as a probe to find indirect signatures of the theoretically predicted spin-singlet supercurrent to spin-triplet supercurrent conversion effect of ferromagnetic domain walls. Here we examine the domain wall induced resistance in Ni stripe in a bilayer Ni/Nb geometry in the normal state and in the superconducting state of Nb. By making a 6um wide gap in the top Nb layer we routed the transport current through the Ni layer in the normal state and in the superconducting state of Nb. In the normal state of Nb, in-field transport measurements showed a clear domain wall magneto-resistance (DWMR) peak near the coercive field, where the domain wall density is expected to be maximum. Interestingly, however, below the superconducting transition temperature of Nb, the DWMR peak of the Ni layer showed a sharp drop in the field range where the number of domain walls becomes maximum. This observation may be a possible signature of magnetic domain wall induced spin-triplet correlations in the Ni layer due to the direct injection of spin-singlet Cooper pairs from Nb into the magnetic domain walls