Electronic, dielectric and optical properties of two dimensional and bulk ice: a multi-scale simulation study

The intercalated water into nanopores exhibits anomalous properties such as ultralow dielectric constant.~Multi-scale modeling and simulations are used to investigate the dielectric properties of various crystalline two-dimensional ices and bulk ices. Although, the structural properties of two-dimensional (2D-) ices have been extensively studied, much less is known about their electronic and optical properties. First, by using density functional theory (DFT) and density functional perturbation theory (DFPT), we calculate the key electronic, optical and dielectric properties of 2D-ices. Performing DFPT calculations, both the ionic and electronic contributions of the dielectric constant are computed. The in-plane electronic dielectric constant is found to be larger than the out-of-plane dielectric constant for all the studied 2D-ices. The in-plane dielectric constant of the electronic response is found to be isotropic for all the studied ices. Secondly, we determined the dipolar dielectric constant of 2D-ices using molecular dynamics simulations (MDS) at finite temperature. The total out-of-plane dielectric constant is found to be larger than 2 for all the studied 2D-ices. Within the framework of the random-phase approximation (RPA), the absorption energy ranges for 2D-ices are found to be in the ultraviolet spectra. For the comparison purposes, we also elucidate the electronic, dielectric and optical properties of four crystalline ices (ice VIII, ice XI, ice Ic and ice Ih) and bulk water

Tracing the evolution of digitalisation research in business and management fields: Bibliometric analysis, topic modelling and deep learning trend forecasting

Research on digitalisation trends and digital topics has become one of the most prolific streams of research within the fields of business and management during the course of the past few years. The purpose of this study is to provide a general picture of the intellectual structure and the conceptual space of this research realm. To this purpose, 6067 publications related to digital topics, indexed in the business and management categories of Web of Science (WoS), and dated from 1990 to 2020 are explored based on the approaches of bibliometric analysis, topic modelling and trend forecasting. The results of the bibliometric analysis comprise insights into the publication and citation structure, the most productive authors, the most productive universities, the most productive countries, the most productive journals, the most cited studies and the most prevalent themes and sub-themes on digitalisation in business and management. In addition, the outcomes of the topic modelling give new knowledge on the latent topical structure along with the rising, falling and fluctuating trends of this literature. In addition, the results of the trend forecasting enable readers to have a glimpse of how the underlying trends of the literature will probably change within the next years until 2025. These results provide guidance and orientation for both academics and practitioners who are initiating or currently developing their efforts in this discipline.info:eu-repo/semantics/acceptedVersio

Digital transformation: towards new research themes and collaborations yet to be explored

This study aimed at providing an overview of research themes and collaborations in the digital transformation scholarship. The methods of co-word analysis, co-author analysis, and network analysis were employed to network-analyze the keywords, countries, and institutions of 2820 research articles published on the digital transformation topic and indexed by the Web of Science database. Our main results indicated that researchers have mostly focused on three aspects of the digital transformation phenomenon including Technological and Industrial View, Organizational and Managerial View, and Global and Social View. Also, it was realized that Technology, Sustainability, Big Data, Information and Communications Technology, Innovation, Industry 4.0, Artificial Intelligence, Business Model, Social Media, and Digitization are the most recurring themes in this field of research. Besides, Small and Medium-Sized Enterprises, Blockchain, Machine Learning, Knowledge Management, and Sustainable Development were respectively identified as the five hottest issues in the digital transformation scholarship. The contribution of our study highlights that European countries and specially the institutions of northern Europe have had better performance in the research collaborations in digital transformation.info:eu-repo/semantics/acceptedVersio

Avaliação do melhoramento de terra estabilizada com cimento e activadores

A terra é uma matéria-prima abundante, com bom comportamento térmico, reciclável e reutilizável, incombustível, não tóxica e sem necessidade de processos de transformação dispendiosos, o que permite eleger este material como uma das alternativas para a construção sustentável. As limitações da terra, enquanto material de construção, em particular o seu comportamento mecânico e a sua susceptibilidade na presença da água, podem ser minimizadas através de processos de estabilização de solos. Este trabalho descreve os resultados de estudos laboratoriais destinados a avaliar os efeitos da utilização do cimento nas propriedades mecânicas e de durabilidade de solos residuais graníticos. As propriedades mecânicas foram avaliadas através de ensaios à compressão simples e à tracção por compressão diametral, enquanto que o desempenho relativamente à durabilidade, foi estudado através de ensaios de absorção de água por capilaridade, ensaios de molhagem-secagem e de gelo-degelo. Foi também avaliado o efeito da saturação na resistência à compressão simples. Foram utilizadas percentagens de 6 e 10% de cimento relativamente à massa de solo seco. O efeito de activadores de baixo custo no solo estabilizado também foi considerado, de modo a tornar o material mais atractivo do ponto de vista económico e de desempenho. Os activadores usados foram: cloreto de sódio, cloreto de cálcio e hidróxido de sódio. O efeito da utilização de activadores foi avaliado no solo estabilizado com 6 % de cimento. Os resultados dos trabalhos experimentais indicam que o cimento aumenta substancialmente o desempenho do solo, enquanto que alguns dos activadores melhoram significativamente algumas das propriedades estudadas no solo estabilizado com cimento. Pode-se portanto concluir, que o uso de alguns activadores de baixo custo pode resultar numa redução significativa no consumo de cimento. Estes resultados podem conduzir a um melhoramento do desempenho e a efeitos ambientais positivos ao mesmo tempo que os custos sofrem uma redução

Fast spectral solutions of the double-gyre problem in a turbulent flow regime

Several semi-analytical models are considered for a double-gyre problem in a turbulent flow regime for which a reference fully numerical eddy-resolving solution is obtained. The semi-analytical models correspond to solving the depth-averaged Navier–Stokes equations using the spectral Galerkin approach. The robustness of the linear and Smagorinsky eddy-viscosity models for turbulent diffusion approximation is investigated. To capture essential properties of the double-gyre configuration, such as the integral kinetic energy, the integral angular momentum, and the jet mean-flow distribution, an improved semi-analytical model is suggested that is inspired by the idea of scale decomposition between the jet and the surrounding flow

Evaluation of some feeding indices of Pomadasys kaakan in the northern Persian Gulf

In this paper the Vacuity Index (VI), Fullness Index (FI) and Food Preference Index (FPI) for the stomach contents of Pomadasys kaakan were evaluated to assess the quantity and kind of food which this fish consumes in the Persian Gulf. A total of 227 specimens were collected from fishing trawlers or landings from November 2005 to September 2006. 24.7% of stomachs were full, 11.9% were semi-full and 63.4% were empty. The seasonal average of VI was 77.4, 44.6, 80.0 and 54.0 % for autumn, winter, spring and summer, respectively. The overall FI was 36.6 with seasonal averages of 22.6, 55.4, 20.0 and 46.0 in autumn, winter, spring and summer, respectively. The main stomach contents were crustaceans (esp. crab & shrimp), fish, mollusks (bivalves, gastropods and cuttlefish), stomatopoda, brittle stars, Lingula sp. and sea weeds. The estimated FPIs for crustaceans were 77.7, fish 32.1, mollusks 28.6 and echinoderms 18.8 %. Overall, the results show that this fish is a relatively frugal species which consumes crustaceans as main food and has adopted itself with ecological changes of the Persian Gulf

Myxobolus spp. (Myxosporea: Myxobolidea) from fishes of the Zayandeh-rud River (Esfahan, Iran); new hosts and locality record

In a parasitic survey of the native and introduced fishes in the Zayandeh-rud River, 5 Myxobolus spp. were found in the gills, fins and skin of examined fish specimens. They include M. varicorhini from fin and M. samgoricus from skin of Capoeta damascina, M. musajevi from gills of Capoeta capoeta gracilis, Myxobolus cristatus from Capoeta aculeata, and M. saidovi from Alburnus sp. Data on the location in the hosts comparing with previous records are provided. The epidemiological importance of Myxobolus spp. in Zayandeh-rud River is also presented. In the present paper the occurrence of five Myxobolus spp. all from endemic fishes from Zayandeh-rud River (a new locality) are recorded from two new hosts; Capoeta damascina, Capoeta aculeata. M. varicorhini and M. saidovi are recorded for the first time from Iranian freshwater fishes

Excitation of the Earth's Chandler wobble by a turbulent oceanic double-gyre

We develop a layer-averaged, multiple-scale spectral ocean model and show how an oceanic double-gyre can communicate with the Earth's Chandler wobble. The overall transfers of energy and angular momentum from the double-gyre to the Chandler wobble are used to calibrate the turbulence parameters of the layer-averaged model. Our model is tested against a multilayer quasi-geostrophic ocean model in turbulent regime, and base states used in parameter identification are obtained from mesoscale eddy resolving numerical simulations. The Chandler wobble excitation function obtained from the model predicts a small role of North Atlantic ocean region on the wobble dynamics as compared to all oceans, in agreement with the existing observations

Analytical assessment process of e-learning domain research between 1980 and 2014

Applying some methods to reduce the time and expenditures of training is inevitable in existing circumstances. Many educational organizations have realized the importance of Electronic Learning (E-learning) and tried to use this approach in leveraging their academic classes. As research in E-learning domain has become one of the most important and interesting subjects, observation in emerging and fading trends of E-learning is a need for the scholars and industry professionals who are interested to study and work in the field. This paper has triggered the investigation and depicting of scientific trends in E-learning by using two scientometric methods named burst detection and clustering analysis. By applying two mentioned methods, the hot topics were identified in the field of E-learning.info:eu-repo/semantics/acceptedVersio