bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparing Single and Hybrid methods of Deep Learning for Remaining Useful Life Prediction of Lithium-ion Batteries
Authors: Zraibi Brahim , Mansouri Mohamed , Okar Chafik
Published: September 2021

The prediction lifetime of a Lithium-ion battery is able to be utilized as an early warning system to prevent the battery’s failure that makes it very significant for assuring safety and reliability. This paper represents a benchmark study that compares its RUL prediction results of single and hybrid methods with similar articles. We suggest a hybrid method, named the CNN-LSTM, which is a combination of Convolutional Neural Network (CNN) and Long Short Term Memory (LSTM), for predicting and improving the accuracy of the remaining useful life (RUL) of Lithium-ion battery. We selected three statistical indicators (MAE, R², and RMSE) to assess the results of performance prediction. Experimental validation is performed using the lithium-ion battery dataset from the NASA and results reveal that the effectiveness of the suggested hybrid method in reducing the prediction error and in achieving better RUL prediction performance compared to the other algorithms.
Theoretical determination of the criteria for bonding quality characterization inside a multilayer by ultrasonic echo-pulse method
Authors: Aboudaoud Idris , Bouazza Faiz , Izbaim Driss , Ouacha El Houssaine , Banouni Hicham
Published: September 2021

In this work we simulated the ultrasonic response of the aluminium/adhesive/aluminium multilayer using the theoretical reflection coefficient. This investigation is based on monitoring the evolution of the amplitude of the theoretical reflection coefficient as a function of the frequency and thickness of the aluminium layer in a first step and as a function of the frequency and thickness of the adhesive layer in a second step. Based on the mode doubling of the aluminium, we found the criteria to be met for such an ultrasonic characterisation of the bonding quality to be validated.
Sentiment Analysis of Covid19 Tweets Using A MapReduce Fuzzified Hybrid Classifier Based On C4.5 Decision Tree and Convolutional Neural Network
Authors: Es-sabery Fatima , Es-sabery Khadija , Garmani Hamid , Hair Abdellatif
Published: September 2021

This contribution proposes a new model for sentiment analysis, which combines the convolutional neural network (CNN), C4.5 decision tree algorithm, and Fuzzy Rule-Based System (FRBS). Our suggested method consists of six parts. Firstly we have applied several pre-processing techniques. Secondly, we have used the fastText method for vectoring the analysed tweets. Thirdly, we have implemented the CNN for extracting and selecting the pertinent features from the tweets. Fourthly, we have fuzzified the CNN output using the Gaussian Fuzzification (GF) method for coping with vague data. Then we have applied fuzziness C4.5 for creating the fuzziness rules. Finally, we have used the General Fuzziness Reasoning (GFR) approach for classifying the new tweets. In summary, our method integrates the advantages of CNN and C4.5 techniques and overcomes the shortcomings of ambiguous data in the tweets using FRBS, which is consists of three-phase: fuzzification phase using GF, inference mechanism using fuzziness C4.5, and defuzzification phase using GFR. Also, to give our approach the ability to deal with the massive data, we have implemented it on the Hadoop framework of five computers. The experiential findings confirmed that our model operates excellently compared to other chosen models form the literature.
Machine Learning based Intrusion Detection for Cyber-Security in IoT Networks
Authors: Khatib Amine , Hamlich Mohamed , Hamad Denis
Published: September 2021

IoT network is a promising technology, IoT implementation is growing rapidly but cybersecurity is still a loophole, detection of attacks in IOT infrastructures is a growing concern in the field of IoT. With the increased use of Internet of Things in different areas, cyber-attacks are also increasing proportionately and can cause failures in the system. IDS becomes the leading security solution. Anomaly based network intrusion detection (IDS) detection plays a major role in protecting networks against various malicious activities. Improving the security of loT networks has become one of the most critical issues. This is due to the large-scale development and deployment of loT devices and the insufficiency of Intrusion Detection Systems (IDS) to be deployed for the use of special purpose networks. In this article, the performance of several machine learning models has been compared to accurately predict attacks on IoT systems, the case of imbalanced classes was subsequently treated using the SMOTE technique. The Nystrom based kernel SVM is the first time used to detect attacks in the IoT network and the results are promising. The evaluation metrics used in the performance comparison are accuracy, precision, recall, f1 score, and auc-roc curve.
A generic metadata management model for heterogeneous sources in a data warehouse
Authors: Oukhouya Lamya , El haddadi Anass , Er-raha Brahim , Asri Hiba
Published: September 2021

For more than 30 decades, data warehouses have been considered the only business intelligence storage system for enterprises. However, with the advent of big data, they have been modernized to support the variety and dynamics of data by adopting the data lake as a centralized data source for heterogeneous sources. Indeed, the data lake is characterized by its flexibility and performance when storing and analyzing data. However, the absence of schema on the data during ingestion increases the risk of the transformation of the data lake into a data swamp, so the use of metadata management is essential to exploit the data lake. In this paper, we will present a conceptual metadata management model for the data lake. Our solution will be based on a functional architecture of the data lake as well as on a set of features allowing the genericity of the metadata model. Furthermore, we will present a set of transformation rules, allowing us to translate our conceptual model into an owl ontology.
Features Clustering Around Latent Variables for High Dimensional Data
Authors: Ghizlane Ez-Zarrad , Wafae Sabbar , Abdelkrim Bekkhoucha
Published: September 2021

Clustering of variables is the task of grouping similar variables into different groups. It may be useful in several situations such as dimensionality reduction, feature selection, and detect redundancies. In the present study, we combine two methods of features clustering the clustering of variables around latent variables (CLV) algorithm and the k-means based co-clustering algorithm (kCC). Indeed, classical CLV cannot be applied to high dimensional data because this approach becomes tedious when the number of features increases.
Digital business transformation: Trends, innovative models, a development program
Authors: Bochulia Tetiana
Published: September 2021

The article is devoted to solving the current issues on current trends in digital transformation of business as an innovative paradigm due to the development of a multimedia society and the new economy. The essence and the process of forming a digital culture are considered that allowed determining the quantitative and qualitative parameters of its model in accordance with the specifics of the activity and the chosen strategy of the company's development. The process of forming an innovative model of enterprise development on the basis of digital transformation is characterized. The stages of forming an enterprise management policy in the context of innovative development are described. Innovative models of digital development are characterized, according to which the possibility to objectively assess factors and conditions of the organization of digital transformation selecting the necessary direction of development becomes available. The "critical" components of the innovative strategy of increasing the organizational stability of the company are identified. The paper proposes a methodological approach to implementing the transformation program that is accompanied by the development of a digital business model with a step-by-step transition to an innovative basis of activity and adaptation to the digital environment of the business ecosystem.
Improving the regulation of the derivatives market as an objective prerequisite for sustainable development of the global financial system
Authors: Novak Oksana , Melnychenko Oleksandr , Oliinyk Oksana
Published: September 2021

The development of financial markets is characterized by the emergence of new financial instruments, in particular derivatives, the risk level analysis of which is complicated. Counterparties are not always fully aware of and do not adequately assess the potential risks of derivatives, which may lead to large financial losses and sometimes bankruptcies. The purpose of the study is to generalize approaches to regulating derivative markets and analyse the adequacy of regulatory influence to ensure sustainable development of the global financial system. The article analyses the approaches of scientists and regulators of the USA and the EU to the regulation of the derivatives market before and after the financial crisis of 2007-2008. Prior to the crisis, most scholars took a liberal approach to derivatives market regulation and recommended monitoring new instruments and not restricting their circulation in any way, emphasizing that effective counterparty risk management and their propensity for self-preservation can prevent excessive risk-taking. The authors analyse the potential risks of derivatives and conclude that exchange-traded derivatives can cause similar processes of liquidity crisis, and, therefore, need additional regulatory tools to ensure the stability of the financial system
The impact of migration on the competitiveness of the region and industry development
Authors: Kotenko Stanislav , Shvindina Hanna , Heiets Iryna
Published: September 2021

The impact of migration on Ukraine is multifaceted. It increases the threat of depopulation, leads to losing a part of the labour and intellectual potential, and thus, may become a factor inhibiting economic development. Today, there is a shortage of workers in almost all activities, especially in industry and construction. At the same time, according to scientists, in the absence of migration, unemployment in Ukraine would be 36.7% higher. Due to foreign earnings, the quality of life in migrant households is improving. Increasing consumer demand can contribute to the economic development of both individual regions and the country as a whole. This article aims to analyse the impact of migration processes on the regional competitiveness. Social, economic, and demographic factors should be taken into account when forming a comprehensive indicator of regional competitiveness. There is a need to evaluate the weight of individual factors and the mechanism of their impact on a comprehensive indicator of the regional competitiveness. Considering the findings of previous studies, the important role of industrial enterprises in assessing the level of regions' competitiveness is emphasized; it is necessary to study in more detail the relationship of migration processes and industrial potential of the region/country.
Knowledge marketing: M4I-mix model of evaluation
Authors: Artyukhova Nadiia , Hordiienko Vita , Motrechko Vira , Kasian Serhii
Published: September 2021

The article is devoted to studying knowledge marketing as a tool for promoting educational and scientific services from the developer (university) to the consumer (industry and business). The main stages of knowledge generation following the DIKW model and the procedure for their further implementation are shown. Based on the bibliometric analysis of keywords clusters and the most popular research topics in the field of "knowledge marketing", the relevance of implementing the chain "idea - investigation - implementation - industry" was confirmed. The M4I-mix approach is proposed for detailing the main processes occurring at each stage of knowledge marketing and identifying significant indicators that should be influenced. Examples of using the M4I-mix approach to promote educational services and commercialize research results are given.
Key indicators of green competitiveness: the EU and Ukraine’s performance
Authors: Chygryn Olena , Lyulyov Oleksii , Pimonenko Tetyana , Myronenko Nataliya
Published: September 2021

Implementation of the Global Sustainable Development Goals 2030 highlights the necessity to accelerate the dynamic processes of changing traditional approaches to doing business, favouring environmentally friendly and responsible ones. The article aims to research the structural environment of developing green competitiveness on the global level. The paper used the methods of structural analysis to determine the main drivers of forming green competitive advantages, correlation analysis for measuring links between the global sustainable competitiveness and countries’ GDP per capita. The authors emphasise the country's level of green competitiveness described by the Global sustainable competitiveness index. The paper investigated the ability of Ukraine to generate competitive advantages by analysing key determinants connected with natural capital, resource intensity, intellectual capital, social cohesion, and governance compared to the world level. The analysis of the essential components of green competitiveness showed a significant number of organisational and economic prerequisites for its formation and improvement. The impacts of sustainable competitiveness on GDP increases over time. In that context it is essential to decide on economic and management policies following the promotion of green competitiveness results. The findings could be used for improving a basis for creating strategies for green competitiveness promotion on the countries’ level.
Sustainable Energy and RES Implementation in Russia
Authors: Orlova Dinara , Smolyakova Sofya , Kwilinski Aleksy
Published: September 2021

Nowadays, the world is undergoing the fourth energy transition process. The global climate agenda, decarbonization tendencies and the necessity to reduce CO2 emissions in order to meet the Paris Climate Agreement criteria are the dominant motives of the sustainable energy development. This article is devoted to analysing the implementation of renewable energy sources in Russian energy sector. The prospect aims are to identify the strengths, to assess the prospects for energy transition, to reveal key issues related to emerging industry and present recommendations on how to address them. It was found out that the implementation of RES is of high potential, especially in certain Russian regions. The key problems that hinder the RES development include low awareness, weak development policy, specific weather conditions, the lack of cutting-edge technologies etc. In this regard, it was suggested to strengthen the regulation within the climate policy, increase investments in green projects and stocks, accelerate the technological development and take other measures to support the emerging industry, along with general awareness-raising in the renewable energy sector.
Multivariate statistical analysis in determining the enterprises’ behavior with resources
Authors: Kravchenko Sergey , Pankova Mariia
Published: September 2021

The threefold concept of sustainable development is largely based on the optimal use of limited resources. In this case, the development of an effective toolkit for the conscious influence of business entities to the effectiveness of using its resource base deserves special attention. The study attempts to substantiate the existence of several basic (characteristic) enterprises types in terms of resources usage results and to identify the key parameters that form a certain style of behavior. This approach includes the methods of multivariate statistical analysis (cluster and discriminant). The results obtained make it possible to assert the existence of four basic enterprises types with different styles of resource management, which affects the level of their resource security. Special attention was paid to identifying indicators that have the greatest separation power. In addition, the classification functions were built, and their quality was confirmed, which makes it possible to model the situation of targeted impact on individual indicators (forecasting the future situation for correction). The research results should contribute to an increase in the degree of the scientific validity recommendations for business entities on the rational use of their resource base (effective regulating the level of resource security).
Engaging in the internationalization of education and SDGs: Case study on the global hub of UNAI on sustainability
Authors: Abazov Rafis
Published: September 2021

The education sector has been identified as one of the key players in globalization processes and implementation of the UN Agenda 2030. The role of education, including higher education, involves not only raising awareness among young people and educators about the sustainable development goals (SDGs) and global environmental changes, but also in mobilizing them for partnerships towards fulfilment of these goals (as defined in SDG-17) and dealing with the challenges of globalization. The purpose of this article is to analyze the engagement of HEIs in internationalization of education, realization of the UN Agenda 2030 and supporting the implementation of SDGs, using as an example the work of the UNAI at the university level. First, the article provides a short literature review on empirical and theoretical aspects of the internationalization of HEIs, looking at how international institutions impact internationalization, organizational culture and the formulation of educational process and international cooperation activities at HEIs. Second, it analyzes organizational tools for internationalization by looking at the international experience and activities of university networks such as UNAI and the impact of those networks on the internationalization of universities. Third, it presents a case study of the work of an international university network, using the example of UNAI Hub at Al-Farabi Kazakh National University, and discusses how the UNAI programs have impacted the perception of internationalization and organizational culture at the university.
The company’s innovation development and marketing communication as a driver of the country’s macroeconomic stability: A quantitative analysis of tendencies
Authors: Rosokhata Anna , Minchenko Mariia , Chykalova Anna , Muzychuk Oleksandr
Published: September 2021

The work aims to analyse the activities of business structures in the issue of quantitative analysis of communication policy, as quantitative is more common and allows assessing the various aspects of communication policy of an enterprise in quantitative units. The tendency formed in conducting the communication policy of business structures is a natural change of the process in a certain time series. The paper graphically presents the relationship among the fundamental aspects of trend formation: time, place, and action. The study allows each promising trend selected from the previous stage of communication policy analysis to assess the success of the factors contributing to the speed of its spread to build input data for grouping trends that will further form promising areas of innovative development of industrial enterprises.
The influence of brands on consumer behaviour in conditions of COVID-19 pandemic: Bibliometric and visualization analysis
Authors: Saher Liudmyla , Kolesnyk Daria , Syhyda Liubov , Fisunenko Nadiya
Published: September 2021

The topic of branding is part of the marketing concept and is actively researched. This study presents a trend analysis, bibliometric overview, and visualization of the current state within the research problem of branding. A review of 1,014 publications from the Scopus database (1996–2020) was conducted. Two combinations of words with a logical operator (“brand” and “consumer behaviour, crisis”) were used. VOSviewer was used to visualize the results and graphically display the material. The analysis helped to draw some valuable conclusions. As a result of the analysis, it is determined that: 1) using filters, the total number of publications in the research field of branding is 984; 2) the growth of the publication activity occurred after 2009. 3) the largest number of studies is conducted by scientists from Europe, North America, Asia and Australia; 4) until 2014, scientists focused on researching the essence of the brand and branding, its benefits, features, etc., then scientists were more focused on the issues of sustainable development, the role and significance of crisis factors, including the impact of the pandemic; 5) the relationships among keywords within the research topic form the following clusters: marketing, corporate social responsibility, brand equity, consumer behaviour, and consumption behaviour. The obtained results are applicable and can be a guidance for further research in the field of branding.
Bands of pure absolutely continuous spectrum for lattice Schrödinger operators with a more general long range condition
Authors: Golénia Sylvain , Mandich Marc-Adrien
Published: September 2021

Commutator methods are applied to get limiting absorption principles for the discrete standard and Molchanov–Vainberg Schrödinger operators, Δ + V and D + V on ℓ2(Zd), with emphasis on d = 1, 2, 3. Considered are electric potentials V satisfying a long range condition of the following type: V−τjκV decays appropriately at infinity for some κ∈N and all 1 ≤ j ≤ d, where τjκV is the potential shifted by κ units on the jth coordinate. More comprehensive results are obtained for small values of κ, e.g., κ = 1, 2, 3, 4. We work in a simplified framework in which the main takeaway appears to be the existence of bands where a limiting absorption principle holds, and hence, pure absolutely continuous spectrum exists. Other decay conditions at infinity for V arise from an isomorphism between Δ and D in dimension 2. Oscillating potentials are examples in application.
Polar glass-ceramics for piezocatalytic applications
Authors: Singh Gurpreet , Sharma Moolchand , Vaish Rahul
Published: September 2021

Glass-ceramics containing oriented Sr2TiSi2O8 fresnoite crystallites were explored for piezocatalysis induced dye degradation capability. The parent glass of the 2SrO–1TiO2–3.3SiO2–0.2K2O–0.1Al2O3 (components are indicated by molar ratio) composition was manufactured using the well-known melt-quench method. The two-parent glass samples were separately heat-treated at the crystallization temperature of 850 and 1000 °C/3 h for obtaining varying amounts of Sr2TiSi2O8 crystallites in the glass matrix. The presence of Sr2TiSi2O8 crystallites on the surface of both glass-ceramics was confirmed using x-ray diffraction. The micrographs obtained from the scanning electron microscope evidenced the presence of more numbers along with the greater sizes of Sr2TiSi2O8 crystallites on the surface of the 1000 °C/3 h sample in comparison to the 850 °C/3 h sample. These glass-ceramics were piezoelectric, as the 1000 °C/3 h sample showed a maximum d33 value of 10 pC/N after sufficient polishing. This non-ferroelectric piezoelectricity was induced due to the oriented crystallization of Sr2TiSi2O8 crystallites in the glass-ceramics. The transparency was decreased in this order: parent glass>850 °C/3 h sample>1000 °C/3 h sample. During the piezocatalytic dye degradation experiment, the degradation of methylene blue dye was found to be 71% and 83% within 300 min under ultrasonication energy using 850 and 1000 °C/3 h glass-ceramics, respectively. The hydroxyl radical (OH˙) was identified as the main active species behind the piezocatalytic dye degradation using glass-ceramics. Hence, this work showed that glass-ceramics can be used for the water-cleaning application using vibrational energy.
Hamiltonian fluid reduction of the 1.5D Vlasov–Maxwell equations
Authors: Chandre C. , Shadwick B. A.
Published: September 2021

We consider the Vlasov–Maxwell equations with one spatial direction and two momenta. By solving the Jacobi identity, we derive reduced Hamiltonian fluid models for the density, the fluid momenta, and the second order moments, related to the pressure tensor. We also provide the Casimir invariants of the reduced Poisson bracket. We show that the linearization of the equations of motion around homogeneous equilibria reproduces some essential features of the kinetic model namely, the Weibel instability.
Stability of double-diffusive natural convection in a vertical fluid layer
Authors: Shankar B. M. , Kumar Jai , Shivakumara I. S.
Published: September 2021

The stability of basic buoyant flow in a vertical fluid layer induced by temperature and solute concentration differences between the vertical boundaries is investigated. The linear dynamics of the perturbed flow is formulated as an eigenvalue problem and solved numerically by employing the Chebyshev collocation method. The validity of Squire's theorem is proved, and therefore, two-dimensional motions are considered. The neutral stability curves defining the threshold of linear instability and the critical values of the thermal Grashof number and wave number at the onset of instability are determined for various values of the Prandtl number Pr, the solute Grashof number GS, and the Lewis number Le. The magnitude of the Prandtl number at which the transition from stationary to travelling-wave mode occurs can be either increased or decreased by tuning the values of GS and Le. For certain combinations of the parameters, there exist one or two closed disconnected travelling-wave neutral curves emphasizing the necessity of multiple thermal Grashof numbers to embark upon the stability of fluid flow, a result of contrast to that of the single-diffusive fluid layer. The mechanism of modal instability is deciphered by using the method of energy budget and four different modes of instability are identified, one of which is new and due entirely to the presence of solutal buoyancy.
Molecular dynamics simulations of inelastic x-ray scattering from shocked copper
Authors: Karnbach O. , Heighway P. G. , McGonegle D. , Rudd R. E. , Gregori G. , Wark J. S.
Published: September 2021

By taking the spatial and temporal Fourier transforms of the coordinates of the atoms in molecular dynamics simulations conducted using an embedded-atom-method potential, we calculate the inelastic scattering of x rays from copper single crystals shocked along [001] to pressures of up to 70 GPa. Above the Hugoniot elastic limit, we find that the copious stacking faults generated at the shock front introduce strong quasi-elastic scattering (QES) that competes with the inelastic scattering signal, which remains discernible within the first Brillouin zone; for specific directions in reciprocal space outside the first zone, the QES dominates the inelastic signal overwhelmingly. The synthetic scattering spectra we generate from our Fourier transforms suggest that energy resolutions of order 10 meV would be required to distinguish inelastic from quasi-elastic scattering within the first Brillouin zone of shock-loaded copper. We further note that high-resolution inelastic scattering also affords the possibility of directly measuring particle velocities via the Doppler shift. These simulations are of relevance to future planned inelastic scattering experiments at x-ray Free Electron Laser facilities.
Planar and three-dimensional damage-free etching of β-Ga2O3 using atomic gallium flux
Authors: Kalarickal Nidhin Kurian , Fiedler Andreas , Dhara Sushovan , Huang Hsien-Lien , Bhuiyan A F M Anhar Uddin , Rahman Mohammad Wahidur , Kim Taeyoung , Xia Zhanbo , Eddine Zane Jamal , Dheenan Ashok , Brenner Mark , Zhao Hongping , Hwang Jinwoo , Rajan Siddharth
Published: September 2021

In situ etching using Ga flux in an ultra-high vacuum environment like molecular beam epitaxy is introduced as a method to make high aspect ratio three-dimensional (3D) structures in β-Ga2O3. Etching of β-Ga2O3 due to excess Ga adatoms on the epilayer surface had been viewed as non-ideal for epitaxial growth especially since it results in plateauing and lowering of the growth rate. In this study, we use this well-known reaction from epitaxial growth to intentionally etch β-Ga2O3. We demonstrate etch rate ranging from 2.9 to 30 nm/min with the highest reported etch rate being only limited by the highest Ga flux used. Patterned in situ etching is also demonstrated and used to study the effect of fin orientation on the sidewall profiles and dopant (Si) segregation on the etched surface. Using in situ Ga etching, we also demonstrate 150 nm wide fins and 200 nm wide nanopillars with high aspect ratio. This etching method could enable future development of highly scaled vertical and lateral 3D devices in β-Ga2O3.
A mesoscopic model of nanoclusters self-assembly on a graphene Moiré
Authors: Khenner Mikhail , Hebenstiel Lars
Published: September 2021

A continuum, post-deposition mesoscopic model of a Moiré-regulated self-assembly of metal nanoclusters on a twisted bilayer graphene is presented. Quasi-two-dimensional nanocluster-like steady-states at a low adsorbate coverage are analytically determined for Pt, Ni, and Pb adsorbates, pointing that nanoclusters self-assemble at the Moiré cell centers. This is followed by the computations of nanoclusters self-assembly dynamics. Differences in the self-assembly efficiency for three chosen metals are highlighted across three typical values of an initial submonolayer coverage and for three temperature regimes. Accounting for the adsorption potential of metal atoms onto graphene leads to a significantly faster nanoclusters self-assembly and has a transient impact on the nanocluster morphologies. A model extensions to the cases of nanoclusters self-assembly on a Moiré formed by a monolayer graphene over a metal substrate, and the electromigration-guided self-assembly on such Moiré are proposed.
Acoustic topological valley transport with multimode edge states
Authors: Wu Tianchong , Jiang Xu , Wu Xin , Han Qiang
Published: September 2021

Acoustic transport through topological edge states in phononic crystals improves the suppression of backscattering, which gives these systems significant potential for controlling sound waves. Recent research shows that only one acoustic edge state caused by topological valley phases can transmit in phononic crystals. This paper proposes a genre of valley phases with one, two, and three topological edge states created by transforming the structure of unit cells. The bulk-edge correspondence indicates that these edge states are topological based on the topological invariant number (i.e., the valley Chern number of one, two, and three) of this system coinciding with the number of topological edge states. Different types of defects are introduced into the phononic crystals, whose transmission spectra show that they can withstand bending defects. These results indicate that these systems have significant potential for application in noise control, acoustic communication, and acoustic-electrical integration.
Distinct thin film growth characteristics determined through comparative dimension reduction techniques
Authors: Gliebe Kimberly , Sehirlioglu Alp
Published: September 2021

Reflection high energy electron diffraction (RHEED) information is critical for the growth of thin films; however, only a small percentage of the data from RHEED videos is typically used. The use of full videos in machine learning can require dimension reduction techniques. In this paper, three dimension reduction techniques, principal component analysis (PCA), non-negative matrix factorization (NMF), and kmeans clustering, are compared to investigate their benefits to the analysis of RHEED data. Three different heterostructures with different growth modes, all deposited on Ti-terminated strontium titanate by pulsed laser deposition, were used for the analysis: lanthanum aluminate with layer-by-layer growth, lithium cobalt oxide with island growth, and strontium ruthenate with a transition from layer-by-layer to step-flow growth. A phase shift in intensity fluctuations of different RHEED spots was discovered and discussed in terms of their sensitivity to the film growth characterization. The diffraction spots that were more sensitive to the growth were differentiated from the spots that are affected by the substrate as a function of film thickness. It was concluded that NMF provides the analysis that is easiest to interpret without the loss of detailed physical information due to its non-negativity constraint and lack of forced orthogonality such as in PCA. Analysis of the full RHEED videos enables a more detailed understanding of growth characteristics and control of growth processes as aided by dimension reduction.
Direct measurement of surface forces: Recent advances and insights
Authors: Lin Weifeng , Klein Jacob
Published: September 2021

The direct measurement of forces between atomically smooth mica surfaces down to sub-nanometer separation was pioneered over 50 years ago and has yielded deep understanding of a range of interfacial effects, not least the forces that determine colloidal stability and self-assembly, the properties of highly confined fluids, and the molecular origin of friction and lubrication. Here, we describe recent advances, including the use of substrates other than mica, probing the shear properties of highly confined fluids including hydration layers, and the modulation of surface forces by surface-attached macromolecules and amphiphiles, together with microscopic imaging of the surface morphology. These advances enabled novel features such as external potential control of the interacting surfaces, new understanding of lubrication in aqueous and biological systems, the design of novel nanoparticles and surface assemblies for modulating frictional dissipation, and insight into the nature of long-ranged attraction between surfactant-hydrophobized surfaces. We conclude by briefly outlining future challenges and opportunities provided by such direct surface forces studies.
Determination of temperature-dependent Fermi resonance in acetonitrile–water binary solution by two-dimensional correlation Raman spectroscopy
Authors: Cao Xianwen , Xing Lu , Wang Ying , Wang Shenghan , Sun Chenglin , Men Zhiwei
Published: September 2021

Acetonitrile (AN), as an organic solvent, has a wide range of applications. The C≡N stretching vibration mode (ν2) and the combination mode (ν3 + ν4) are coupled by Fermi resonance (FR). In this work, the phase transition and the interaction mechanism of the 60% AN–water binary solution (AN–Water) were analyzed by calculating FR parameters and two-dimensional correlation Raman spectroscopy (2DCRS). The change in the ν2 band and the base bands ν3 and ν4 caused energy transfer by anharmonic interaction, which led to a change in FR parameters. With a reduced temperature, the energy transfer was caused by microheterogeneity and the energy transfer effect (293–273 K), the phase separation (263–233 K), and the phase transition of AN (223–173 K). The 2DCRS and Gaussian deconvolution provided more information on FR, which revealed the interaction mechanism of the Fermi doublet. The polarity and binding modes of molecules provided a new perspective for analyzing the transmission of electrons and ions in the electrolyte at different temperatures.
On closures for reduced order models—A spectrum of first-principle to machine-learned avenues
Authors: Ahmed Shady E. , Pawar Suraj , San Omer , Rasheed Adil , Iliescu Traian , Noack Bernd R.
Published: September 2021

For over a century, reduced order models (ROMs) have been a fundamental discipline of theoretical fluid mechanics. Early examples include Galerkin models inspired by the Orr–Sommerfeld stability equation and numerous vortex models, of which the von Kármán vortex street is one of the most prominent. Subsequent ROMs typically relied on first principles, like mathematical Galerkin models, weakly nonlinear stability theory, and two- and three-dimensional vortex models. Aubry et al. [J. Fluid Mech. 192, 115–173 (1988)] pioneered the data-driven proper orthogonal decomposition (POD) modeling. In early POD modeling, available data were used to build an optimal basis, which was then utilized in a classical Galerkin procedure to construct the ROM, but data have made a profound impact on ROMs beyond the Galerkin expansion. In this paper, we take a modest step and illustrate the impact of data-driven modeling on one significant ROM area. Specifically, we focus on ROM closures, which are correction terms that are added to the classical ROMs in order to model the effect of the discarded ROM modes in under-resolved simulations. Through simple examples, we illustrate the main modeling principles used to construct the classical ROMs, motivate and introduce modern ROM closures, and show how data-driven modeling, artificial intelligence, and machine learning have changed the standard ROM methodology over the last two decades. Finally, we outline our vision on how the state-of-the-art data-driven modeling can continue to reshape the field of reduced order modeling.
Interaction of a turbulent spot with a two-dimensional cavity
Authors: Wu S. , Yaras M. I.
Published: September 2021

A study with experimental and numerical components is conducted to establish the effect of a two-dimensional surface cavity on the structure and growth rate of a turbulent spot. The spot is artificially created in a two-dimensional laminar boundary layer developing under zero streamwise pressure gradient. Interactions of the turbulent spot and its wake with the Kelvin–Helmholtz rollers of the cavity shear layer are shown to result in significant increases in its lateral and streamwise growth rates. The underlying physics of these developments are identified.
Optical frequency comb stabilized to a fiber delay line
Authors: Tian Haochen , Meng Fei , Wang Kai , Lin Baike , Cao Shiying , Fang Zhanjun , Song Youjian , Hu Minglie
Published: September 2021

We have developed a simple and practical optical frequency comb (OFC) stabilization method for comb linewidth reduction in this Letter. Two comb modes of an Er-fiber optical frequency comb (OFC) have been phase-locked to a kilometer-long fiber delay line, while narrow linewidth lasers are not required as optical references. The fractional frequency stability of the 1542-nm comb mode in the Er-fiber OFC reaches 9.13 × 10−13 at 12.8 ms average time, and its short-term linewidth is 580 Hz, which is compressed by a factor of ∼170 compared to the free-running condition. The whole stabilization scheme gets rid of nonlinear progress, which can be an alternative approach for OFC stabilization, especially in ultra-high repetition-rate combs, e.g., electro-optic combs, quantum cascade laser combs, and micro-combs with low pulse energy.
Rotational motion of spherical dust in plasmas with magnetic fields
Authors: Simons L. , Long A.
Published: September 2021

The rotational dynamics of spherical, conducting dust grains in collisionless plasmas due to asymmetric momentum and current collection in the presence of a uniform magnetic field was modeled using the Monte Carlo code DiMPl. The dependence of the torque, equilibrium rotation rate, and equilibration timescale on the strength of the magnetic field and the surface potential was determined. The direction and magnitude of the rotational velocity were found to depend on the sign and magnitude of the surface potential. At a fixed positive charge, dust rotated anti-parallel to the magnetic field due to accumulation of angular momentum from electron impact while at the floating potential, dust rotated parallel to the magnetic field. This model was used to explain existing experimental observations of isolated dust grain rotation in low temperature discharges. In isothermal tokamak plasmas, equilibrium rotation rates of the order 105 Hz are anticipated to occur over time-scales of 20 ms which will have important consequences for dust dynamics.
Effect of transverse jet position on flame propagation regime
Authors: Zhao Wandong , Liang Jianhan , Deiterding Ralf , Cai Xiaodong , Wang Xinxin
Published: September 2021

We studied the mechanisms of flame acceleration (FA) and deflagration to detonation transition (DDT) triggered by a combination of solid and jet obstacles. The Navier–Stokes equations with a detailed hydrogen–air kinetics model were utilized. Vast Kelvin–Helmholtz instabilities generate intensive turbulence–flame interactions, leading to an increase in surface area and high propagation velocity. The jet position has a significant effect on the FA and DDT. A choking flame and detonation flame are obtained by the transverse jet with different positions and mixing times even though in a lower blockage ratio.
Perspective on traveling wave microwave parametric amplifiers
Authors: Esposito Martina , Ranadive Arpit , Planat Luca , Roch Nicolas
Published: September 2021

Quantum-limited microwave parametric amplifiers are genuine key pillars for rising quantum technologies and, in general, for applications that rely on the successful readout of weak microwave signals by adding only the minimum amount of noise allowed by quantum mechanics. In this Perspective, after providing a brief overview on the different families of parametric microwave amplifiers, we focus on traveling wave parametric amplifiers, underlining the key achievements of the last few years and the present open challenges. We also discuss possible new research directions beyond amplification such as exploring these devices as a platform for multi-mode entanglement generation and for the development of single photon detectors.
Detailed quasiclassical dynamics of the F− + CH3Br reaction on an ab initio analytical potential energy surface
Authors: Tajti Viktor , Győri Tibor , Czakó Gábor
Published: September 2021

Dynamics and mechanisms of the F− + CH3Br(v = 0) → Br− + CH3F (SN2 via Walden inversion, front-side attack, and double inversion), F− + inverted-CH3Br (induced inversion), HF + CH2Br− (proton abstraction), and FH⋯Br− + 1CH2 reactions are investigated using a high-level global ab initio potential energy surface, the quasiclassical trajectory method, as well as non-standard configuration- and mode-specific analysis techniques. A vector-projection method is used to identify inversion and retention trajectories; then, a transition-state-attack-angle-based approach unambiguously separates the front-side attack and the double-inversion retention pathways. The Walden-inversion SN2 channel becomes direct rebound dominated with increasing collision energy as indicated by backward scattering, initial back-side attack preference, and the redshifting of product internal energy peaks in accord with CF stretching populations. In the minor retention and induced-inversion pathways, almost the entire available energy transfers into product rotation–vibration, and retention mainly proceeds with indirect, slow double inversion following induced inversion with about 50% probability. Proton abstraction is dominated by direct stripping (evidenced by forward scattering) with CH3-side initial attack preference, providing mainly vibrationally ground state products with significant zero-point energy violation.
Property-optimized Gaussian basis sets for lanthanides
Authors: Rappoport Dmitrij
Published: September 2021

Property-optimized Gaussian basis sets of split-valence, triple-zeta valence, and quadruple-zeta valence quality are developed for the lanthanides Ce–Lu for use with small-core relativistic effective core potentials. They are constructed in a systematic fashion by augmenting def2 orbital basis sets with diffuse basis functions and minimizing negative static isotropic polarizabilities of lanthanide atoms with respect to basis set exponents within the unrestricted Hartree–Fock method. The basis set quality is assessed using a test set of 70 molecules containing the lanthanides in their common oxidation states and f electron occupations. 5d orbital occupation turns out to be the determining factor for the basis set convergence of polarizabilities in lanthanide atoms and the molecular test set. Therefore, two series of property-optimized basis sets are defined. The augmented def2-SVPD, def2-TZVPPD, and def2-QZVPPD basis sets balance the accuracy of polarizabilities across lanthanide oxidation states. The relative errors in atomic and molecular polarizability calculations are ≤8% for augmented split-valence basis sets, ≤ 2.5% for augmented triple-zeta valence basis sets, and ≤1% for augmented quadruple-zeta valence basis sets. In addition, extended def2-TZVPPDD and def2-QZVPPDD are provided for accurate calculations of lanthanide atoms and neutral clusters. The property-optimized basis sets developed in this work are shown to accurately reproduce electronic absorption spectra of a series of LnCp3′− complexes (Cp′ = C5H4SiMe3, Ln = Ce–Nd, Sm) with time-dependent density functional theory.
Practice nurse provision of early medical abortion in general practice: opportunities and limitations
Authors: Moulton Jessica E. , Subasinghe Asvini K. , Mazza Danielle
Published: September 2021

Approximately one in three Australian women with an unintended pregnancy will have an abortion, yet significant barriers remain to ensure the delivery of equitable and timely medical abortion services, including lack of trained providers, high out-of-pocket costs, abortion stigma, conscientious objection and large geographical distance to services. Practice nurses can be suitably trained to provide early medical abortion in general practice; however, there remain several key limitations to the implementation of nurse-led models of care. This forum article discusses these limitations, including issues concerning legislation, funding models, lack of access to medical abortion training, practice structure and systems, and makes recommendations as to how increased access to medical abortion in Australia can be achieved.
Functional succinate dehydrogenase deficiency is a common adverse feature of clear cell renal cancer
Authors: Aggarwal Ritesh K. , Luchtel Rebecca A. , Machha Venkata , Tischer Alexander , Zou Yiyu , Pradhan Kith , Ashai Nadia , Ramachandra Nandini , Albanese Joseph M. , Yang Jung-in , Wang Xiaoyang , Aluri Srinivas , Gordon Shanisha , Aboumohamed Ahmed , Gartrell Benjamin A. , Hafizi Sassan , Pullman James , Shenoy Niraj
Published: September 2021

Significance

This study demonstrates that underexpression of succinate dehydrogenase (SDH) subunits resulting in accumulation of oncogenic succinate is a common, adverse, epigenetic modulating feature in clear cell renal cell carcinoma (ccRCC), during pathogenesis and progression. The study sheds light on the mechanisms of down-regulation of SDH subunits in ccRCC and deciphers the consequent oncogenic effects. It shows that functional SDH deficiency is a common feature of ccRCC (∼80% of all kidney cancers), and not just limited to the 0.05 to 0.5% of kidney cancers with germline SDH mutations.
The impact of crowdsourcing and online collaboration in professional translation
Authors: Jiménez-Crespo Miguel A.
Published: September 2021

The emergence of crowdsourcing has opened up novel ways to initiate, produce and deliver translations in our
digitally connected world. New practices and processes brought up by these phenomena have undeniably impacted different
collectives with an interest in translation, such as language service providers (LSPs), professionals, and Translation Studies
(TS). It has also been argued that crowdsourcing can impact public perceptions of translation, rising ethical concerns, issues
related to the visibility of translation, or whether everyone can potentially translate (McDonough-Dolmaya 2012). This paper analyzes its potential impact on the realm of professional translation, an issue
raised several years ago by a European Union Commission publication (2012, 37–38). It critically analyzes whether the much-feared
socioeconomic and socio-professional impact on working conditions of professionals is underway or not. It represents an attempt at
charting the potential influence of crowdsourcing on the profession through a critical review of existing literature and industry
publications.