bluuebunny/crossref_metadata_2025 huggingface dataset:
Bisimulations for delayed switched Boolean control networks and its application in controllability
Authors: Yu Weiyong , Deng Zhenhua , Guo Qianjin , Liu Qiang
Published: June 2023

This paper investigates bisimulation relations of delayed switched Boolean control networks (DSBCNs), using the semi‐tensor product (STP) approach. Firstly, the notion of bisimulation in DSBCNs is formalized. Subsequently, based on the skeleton matrix of DSBCN, two necessary and sufficient conditions are derived for checking this notion. Moreover, as an application of bisimulation relations, this paper explores the propagation of controllability for DSBCNs through a bisimulation relation. It shows the possibility that the controllability of a DSBCN can be inferred by studying a potentially simpler DSBCN. At last, two examples are proposed to illustrate the efficiency of the obtained results.
Non‐invasive ventilation treatment for patients with chronic obstructive pulmonary disease
Authors: Tehrani Fleur T. , Roum James H.
Published: June 2023

Chronic obstructive pulmonary disease (COPD) affects the lives of millions of patients worldwide. Patients with advanced COPD may require non‐invasive ventilation (NIV) to support the resultant deficiencies of the respiratory system. The purpose of this study was to evaluate the effects of varying the continuous positive airway pressure (CPAP) and oxygen supplementation components of NIV on simulated COPD patients by using an established and detailed model of the human respiratory system. The model used in the study simulates features of advanced COPD including the effects on the changes in ventilation control, increases in respiratory dead space and airway resistance, and the acid–base shifts in the blood seen in these patients over time. The results of the study have been compared with and found to be in general agreement with available clinical data. Our results demonstrate that under non‐emergency conditions, low levels of oxygen supplementation combined with low levels of CPAP therapy seem to improve hypoxemia and hypercapnia in the model, whereas prolonged high‐level CPAP and moderate‐to‐high levels of oxygen supplementation do not. The authors conclude that such modelling may be useful to help guide beneficial interventions for COPD patients using NIV.
Real‐time passenger flow anomaly detection in metro system
Authors: Wei Xiulan , Zhang Yong , Zhang Xinyu , Ge Qibin , Yin Baocai
Published: June 2023

Real‐time passenger‐flow anomaly detection at all metro stations is a very critical task for advanced Internet management. Robust principal component analysis (RPCA) based method has often been employed for anomaly detection task of multivariate time series data. However, it ignores the spatio‐temporal features of regular passenger‐flow patterns, resulting in a decrease in the accuracy of anomaly detection. In this paper, RT‐STRPCA model integrating temporal periodicity and spatial similarity is proposed to address the above issues. RT‐STRPCA model detects anomalies by decomposing the observation data into normal component and anomaly component. The spatio‐temporal constraints are taken into account to extract anomalies more accurately. The real‐time anomaly detection are realized by a sliding window. The performance of RT‐STRPCA model is evaluated on synthetic datasets and real‐world datasets. The experimental results on synthetic datasets demonstrate that the method achieves more accurate real‐time anomaly detection than baseline approaches and the result on real‐world datasets verify the utility and effectiveness of the proposed method.
A surface plasmon resonance haemoglobin concentration sensor based on D‐type optical fibre with a graphene‐gold surface architecture
Authors: Shi Zhen‐Jiang , Guo Shi‐Liang , Li Xin , Li Wen‐Chao , Li Zhi‐Quan
Published: June 2023

In this study, a surface plasmon resonance sensor for detecting haemoglobin concentration based on a D‐type optical fibre with a graphene‐gold surface architecture is proposed. The graphene‐gold surface architecture included a 50 nm thick gold film and monolayer graphene film, which were decorated on a 10 mm long D‐type sensing region. The proposed sensor worked in wavelength interrogation mode, with the light wavelength ranging from 400 to 1100 nm. The authors realised the D‐type optical fibre surface polishing process, the gold film vacuum coating process, and the chemical‐vapour‐deposited graphene's wet transfer process. Furthermore, the fabricated sensors were used to detect the refractive index (RI) of haemoglobin samples, which varied from 1.331 to 1.346. Experiment results show that the fitted RI sensitivity of the sensor decorated with gold and graphene reaches 1874.41 nm/RIU, 4.995% higher than that of the sensor decorated only with gold. The concentration sensitivity of the sensor coated with gold and graphene film is 4.96 nm/(g/dL), and the proposed sensor can provide a resolution of 20.2 mg/dL for haemoglobin concentration detection.
A guide to unmanned aerial vehicles performance analysis—the MQ‐9 unmanned air vehicle case study
Authors: Zountouridou Erietta , Kiokes George , Dimeas Aris , Prousalidis John , Hatziargyriou Nikos
Published: June 2023

Great efforts are devoted for integrating Renewable Energy Sources (RES) on the propulsion system of Unmanned Air Vehicles (UAVs). This is applicable to small UAVs, having a horizon to expand to large UAVs within the next decades. For the conventional propulsion systems to be replaced, the required power needs of the aircraft should first be examined. The required power depends on the UAV's flight stage from takeoff to landing, whereas its calculation varies with regard to the propulsion system type, which is separated into two main categories, the propelled‐driven engines and the jet engines. Two obstacles are arising. First, the parameters needed for the power estimation are commercially sensitive and second the analysis alters with respect to the engine's type. This paper focuses on the mathematical analysis of the required power for both the main propulsion systems, presented extensively for each flight phase, proposing, at the same time, a parameter estimation method which is applicable to any UAV type. The main purpose of this paper is to act as a guide for the calculation of any type UAV's required power at any flight stage. To validate the analysis, the MQ‐9 Reaper/Predator B, a High Altitude Long Endurance (HALE) turboprop UAV produced by General Atomics is analysed. Its unknown parameters are estimated and based on a selected flight profile, the required power in terms of horsepower from takeoff to landing is assessed, for two scenarios regarding the aircraft's initial weight. In the first scenario the UAV has the maximum gross takeoff weight, whereas in the second scenario it does not carry any payload. The estimated required shaft power per flight phase for each scenario is then marked into the TPE331‐10 turboprop engine characteristic curves.
The post-disk (or primordial) spin distribution of M dwarf stars
Authors: Gehrig L. , Gaidos E. , Güdel M.
Published: June 2023

Context. The rotation periods of young low-mass stars after disks have dissipated (≲-pagination10 Myr) but before magnetized winds have removed significant angular momentum is an important launch point for gyrochronology and models of stellar rotational evolution; the rotation of these stars also regulates the magnetic activity and the intensity of high-energy emission that affects any close-in planets. A recent analysis of young M dwarf stars suggests a distribution of specific angular momentum (SAM) that is mass-independent, but the physical basis of this observation is unclear.

Aims. We investigate the influence of an accretion disk on the angular momentum (AM) evolution of young M dwarfs, whose parameters govern the AM distribution after the disk phase, and whether this leads to a mass-independent distribution of SAM.

Methods. We used a combination of protostellar spin and implicit hydrodynamic disk evolution models to model the innermost disk (∼0.01 AU), including a self-consistent calculation of the accretion rate onto the star, non-Keplerian disk rotation, and the influence of stellar magnetic torques over the entire disk lifetime. We executed and analyzed over 500 long-term simulations of the combined stellar and disk evolution.

Results. We find that above an initial rate of Ṁcrit ∼ 10−8 M⊙ yr−1, accretion “erases” the initial SAM of M dwarfs during the disk lifetime, and stellar rotation converges to values of SAM that are largely independent of initial conditions. For stellar masses > 0.3 M⊙, we find that observed initial accretion rates Ṁinit are comparable to or exceed Ṁcrit. Furthermore, stellar SAM after the disk phase scales with the stellar magnetic field strength as a power law with an exponent of −1.1. For lower stellar masses, Ṁinit is predicted to be smaller than Ṁcrit and the initial conditions are imprinted in the stellar SAM after the disk phase.

Conclusions. To explain the observed mass-independent distribution of SAM, the stellar magnetic field strength has to range between 20 G and 500 G (700 G and 1500 G) for a 0.1 M⊙ (0.6 M⊙) star. These values match observed large-scale magnetic field measurements of young M dwarfs and the positive relation between stellar mass and magnetic field strength agrees with a theoretically motivated scaling relation. The scaling law between stellar SAM, mass, and the magnetic field strength is consistent for young stars, where these parameters are constrained by observations. Due to the very limited number of available data, we advocate for efforts to obtain more such measurements. Our results provide new constraints on the relation between stellar mass and magnetic field strength and they can be used as initial conditions for future stellar spin models, starting after the disk phase.
The star in RNO 54: A possible post-FUor with a short faint jet
Authors: Magakian T. Yu. , Movsessian T. A. , Andreasyan H. R. , Moiseev A. V. , Uklein R. I.
Published: June 2023

Aims. The aim of the present study is to analyze the spectra of an unusual pre-main sequence star in the cometary nebula RNO 54, which is suspected by several researchers to be a FUori-like object.

Methods. We performed long-slit spectroscopy of the star using the 6m telescope with the SCORPIO-2 multi-mode focal reducer.

Results. We discover a short (~4″ or ~6000 AU) and faint emission shock-excited jet from this star, probably oriented toward the long axis of the nebular ellipse. The spectral type of the star is estimated as G0-2 II; we confirm the split of the Li I absorption line, which is a typical sign indicating a FUori-like spectrum. Our analysis of the available data reveals an almost null photometric variability over at least the last 20 years. The lower limit of the bolometric luminosity of the star is estimated as 300 L⊙. Our study supports the classification of RNO 54 as a FUor-like star in the long post-outburst stage.
The performance of four domestic rooftop 7.8 kW − PV in the Kingdom of Bahrain: toward low building emission
Authors: Alnaser Naser W.
Published: June 2023

This paper reports the performance of four domestic houses at different locations in Bahrain, each have 7.8 kW of PV on the roof, and all panels are tilted at 12°, but the azimuth of the panels (orientation) in these houses varies slightly from south (±10°); depending on roof space availability and building surroundings. The data of year 2019 have been used because all these domestic houses were monitored, maintained, and cleaned by an assigned company from the government. The annual solar electricity generated was 11,329 kWh, 11,448 kWh, 10,978 kWh, and 9995 kWh for houses # 4, # 2, #1, and # 3, respectively. The annual Specific Yield (SY) obtained was 1468 kWh/kW, 1452 kWh/kW, 1407 kWh/kW and 1254 kWh/kW for houses # 2, #4, # 1, and # 3, respectively; this makes the daily average SY equals to 4.02 kWh/kW, 3.98 kWh/kW, 3.85 kWh/kW, and 3.43 kWh/kW, respectively. The average performance ratio (PR) of each PV system were found to range from 75.1% to 65.6%. The PV system performs better in house #4 due to its azimuth PV panels' angle (orientation) which is closest to the south direction. A polynomial equation is established, relating the month number (X) and the monthly average of monthly solar electricity generated as well as the monthly specific yield (Y). This work shows that installing a 7.8 kWp of PV on the roof of all residential building in Bahrain will reduce the total CO2 emission in Bahrain by 39.0% (4.637 tons) per year, saving 38,567 ft3 of natural gas. This is a step towards low-carbon building; in an attempt to make Bahrain a zero carbon by 2060.
Well ev-covered trees
Authors: Boutrig Razika , Chellali Mustapha
Published: June 2023

An edge in a graph G = (V, E) is said to ev-dominate the vertices incident to it as well as the vertices adjacent to these incident vertices. A subset F ⊆ E is an edge-vertex dominating set (or simply, ev-dominating set) if every vertex is ev-dominated by at least one edge of F. The ev-domination number γev(G) is the minimum cardinality of a ev-dominating set of G. An ev-dominating set is independent if its edges are independent. The independent ev-domination number iev(G) is the minimum cardinality of an independent ev-dominating set and the upper independent ev-domination number βev(G) is the maximum cardinality of a minimal independent ev-dominating set of G. In this paper, we show that for every nontrivial tree T, γev(T) = iev(T) ≤ γ(T) ≤ βev(T), where γ(T) is the domination number of T. Moreover, we provide a characterization of all trees T with iev(T) = βev(T), which we call well ev-covered trees, as well as a characterization of all trees T with γev(T) = iev(T) = γ(T).
Centering on People: How Hearing Care Professionals Can Adapt to Consumers' Need and Outcomes
Authors: Brice Sophie , Timmer Barbra H. B. , Barr Caitlin
Published: June 2023

Audiology is experiencing exponential growth in technology, service, and provision options. These advancements give hearing care professionals the opportunity to revise, potentially improve, and adapt to the modern hearing care landscape to better serve the modern consumer. Consumer needs guide care planning and delivery, with the goal of achieving outcomes that are important to both the consumer and the clinician. The changes available to the hearing care industry can also enable consumers' needs to be identified and served in a more holistic and personalized manner than has previously been possible. The purpose of this article is to explain and encourage hearing care professionals to adopt a mindset of doing whatever is reasonable and clinically appropriate to meet the need and desires of the consumer by implementing choice in service, technology, and channel across whichever model of care adopted by a provider.
Deep Learning for the Assessment of Facial Nerve Palsy: Opportunities and Challenges
Authors: Boochoon Kieran , Mottaghi Ali , Aziz Aya , Pepper Jon-Paul
Published: June 2023

Automated evaluation of facial palsy using machine learning offers a promising solution to the limitations of current assessment methods, which can be time-consuming, labor-intensive, and subject to clinician bias. Deep learning-driven systems have the potential to rapidly triage patients with varying levels of palsy severity and accurately track recovery over time. However, developing a clinically usable tool faces several challenges, such as data quality, inherent biases in machine learning algorithms, and explainability of decision-making processes. The development of the eFACE scale and its associated software has improved clinician scoring of facial palsy. Additionally, Emotrics is a semiautomated tool that provides quantitative data of facial landmarks on patient photographs. The ideal artificial intelligence (AI)-enabled system would analyze patient videos in real time, extracting anatomic landmark data to quantify symmetry and movement, and estimate clinical eFACE scores. This would not replace clinician eFACE scoring but would offer a rapid automated estimate of both anatomic data, similar to Emotrics, and clinical severity, similar to the eFACE. This review explores the current state of facial palsy assessment, recent advancements in AI, and the opportunities and challenges in developing an AI-driven solution.
Family-friendly policy evolution: a bibliometric study
Authors: Li Zheng-Dong , Zhang Bei
Published: June 2023

This paper uses the bibliometric method to analyze the basic characteristics and disciplinary knowledge structure of family-friendly policy research, as well as research hotspots and trends. The basic data source is the literature in the Web of Science Core Collection from 1985 to 2022. The following findings were obtained. First, the number of publications and citations in this field have increased exponentially, with scholars and research institutions from the US dominating the field of family-friendly policy research. Second, family-friendly policy research has been concentrated in the fields of management, sociology, and psychology, with a gradual trend toward cross-disciplinary integration, but a core group of authors has yet to be formed. Third, most of the family-friendly policy research has been conducted at the organizational level to explore the impact of family-friendly policies, with married women as the main research object. Finally, current family-friendly policy research focuses on policy fairness, childcare services, employee satisfaction, and work flexibility. Future research should focus on the dynamics of family-friendly policies and the empirical analysis of cross-level integration to improve the matching of policies with employee orientation. This study fills an analytical gap in the integration of family-friendly policies and scientometrics, proposes an expandable field of family-friendly policy research and research methods, and provides references and insights for future family-friendly policy research and practice.
Financial development and income inequality in Africa
Authors: Okafor Victoria I. , Olurinola Isaiah O. , Bowale Ebenezer , Osabohien Romanus
Published: June 2023

Across the globe, a rise in income inequality has been experienced for the last two decades, particularly in developing countries. This problem of income inequality poses a challenge to Africa’s ability to attain the United Nations (UN) Sustainment Development Goals (SDGs) of reduced inequalities (SDG-10). Against this backdrop, there is a need to harness the potential of financial development to reduce income inequality in Africa. Therefore, this study empirically examines how financial development affects income inequality in Africa. Financial development dimensions, access, depth, efficiency, and stability were considered to achieve the study’s objective. The study applied the system generalized method of moments (SGMM) to analyse data and the findings showed that each dimension of financial development had a varying impact on income inequality. Access, stability and efficiency components of financial development reduce income inequality, while the depth dimension of financial development exacerbates income inequality in Africa. Therefore, the study recommends that policymakers should not neglect other dimensions of finance in facilitating economic development.
Instrumentalisation of critical discourse studies: a linguistic analysis of public relations concepts in the CDS journal article abstracts (2000–2020)
Authors: Wang Huabin
Published: June 2023

Driven by its problem-oriented nature, research of Critical Discourse Studies (CDS) employs an interdisciplinary approach to addressing social problems and concludes different levels of discourse practices. Among the disciplines that CDS scholars touch on, public relations (PR) stands out as one of the most inspiring, whose studies have implied the practicality of CDS to critique PR, explicating how institutional and media discourses shape stakeholders’ attitude toward the management process and further negotiate their identities and power relations. Nevertheless, little research has tackled the opposite, which is how the interconnected discipline of PR and its theories benefit CDS research. By adopting van Leeuwen (2005)’s integrationist model of conducting interdisciplinary research, the present case conducts an analysis of PR concepts used in the CDS journal article abstracts during 2000 and 2020, with three terms of “image”, “stakeholder”, and “strategy” as a case study. It argues that the use of PR concepts instrumentalises CDS, which offers analytic tools of communication for CDS scholars to refer to and helps to interpret the management power use and its discursive patterns in a CDS project. This ontological study not only offers insights into developing an interdisciplinary contribution during the institutionalisation of CDS but shows how both disciplines of PR and CDS have fostered a two-way development from linguistic and non-linguistic perspectives.
A fast tracking method for magnetic abnormalities using distributed Overhauser magnetometer system based on genetic algorithm
Authors: Luo Wang , Ge Jian , Liu Huan , Wu Shuang , Wang Hongpeng , Yuan Zhiwen , Luan Xinqun , Dong Haobin , Fukushima Edwardo F.
Published: June 2023

Magnetic anomaly detection technologies have been widely used for tracking moving targets. In this paper, we present a fast-tracking method for magnetic abnormalities using a distributed Overhauser magnetometer system based on the genetic algorithm. Our proposed framework of the Overhauser magnetometer system employs multiple sensors to eliminate background interference, and the genetic algorithm efficiently solves magnetic anomaly data without requiring the derivation of the objective function. Test platforms were built to evaluate the distributed Overhauser magnetometer system and the genetic algorithm. Results from the natural outdoor magnetism laboratories showed that the noise of our presented magnetometers was below 0.134 nT. The optimal factors for solution precision and effectiveness in the genetic algorithm were obtained from the simulation. Moreover, the outdoor tracking experiments indicated that the proposed method could accurately and quickly detect the moving ferromagnetic object within 6.9% maximum positioning error in 0.55 m, and the tracking precision of the object velocity can get 5.88% maximum error in 4.33 km/h.
Radiation burnthrough measurements to infer opacity at conditions close to the solar radiative zone–convective zone boundary
Authors: Hoarty D. J. , Morton J. , Rougier J. C. , Rubery M. , Opachich Y. P. , Swatton D. , Richardson S. , Heeter R. F. , McLean K. , Rose S. J. , Perry T. S. , Remington B.
Published: June 2023

Recent measurements at the Sandia National Laboratory of the x-ray transmission of iron plasma have inferred opacities much higher than predicted by theory, which casts doubt on modeling of iron x-ray radiative opacity at conditions close to the solar convective zone-radiative zone boundary. An increased radiative opacity of the solar mixture, in particular iron, is a possible explanation for the disagreement in the position of the solar convection zone-radiative zone boundary as measured by helioseismology and predicted by modeling using the most recent photosphere analysis of the elemental composition. Here, we present data from radiation burnthrough experiments, which do not support a large increase in the opacity of iron at conditions close to the base of the solar convection zone and provide a constraint on the possible values of both the mean opacity and the opacity in the x-ray range of the Sandia experiments. The data agree with opacity values from current state-of-the-art opacity modeling using the CASSANDRA opacity code.
Prevalence of multistability and nonstationarity in driven chemical networks
Authors: Nicolaou Zachary G. , Nicholson Schuyler B. , Motter Adilson E. , Green Jason R.
Published: June 2023

External flows of energy, entropy, and matter can cause sudden transitions in the stability of biological and industrial systems, fundamentally altering their dynamical function. How might we control and design these transitions in chemical reaction networks? Here, we analyze transitions giving rise to complex behavior in random reaction networks subject to external driving forces. In the absence of driving, we characterize the uniqueness of the steady state and identify the percolation of a giant connected component in these networks as the number of reactions increases. When subject to chemical driving (influx and outflux of chemical species), the steady state can undergo bifurcations, leading to multistability or oscillatory dynamics. By quantifying the prevalence of these bifurcations, we show how chemical driving and network sparsity tend to promote the emergence of these complex dynamics and increased rates of entropy production. We show that catalysis also plays an important role in the emergence of complexity, strongly correlating with the prevalence of bifurcations. Our results suggest that coupling a minimal number of chemical signatures with external driving can lead to features present in biochemical processes and abiogenesis.
Mechanistic study of ZnSe nanocrystal formation from zinc halides
Authors: Mingabudinova Leila , Giordano Luca , Tessier Mickael D. , Hens Zeger , Schiettecatte Pieter
Published: June 2023

We studied the formation of zinc selenide (ZnSe) from zinc chloride (ZnCl2) and trioctylphosphine selenide (TOP=Se) in oleylamine, a chemistry originally proposed to grow ZnSe shells around InP core quantum dots. By monitoring the formation of ZnSe in reactions with and without InP seeds by quantitative absorbance and nuclear magnetic resonance (NMR) spectroscopy, we observe that the ZnSe formation rate is independent of the presence of InP cores. Similar to the seeded growth of CdSe and CdS, this observation supports a ZnSe growth mechanism through the inclusion of reactive ZnSe monomers that form homogeneously in the solution. Furthermore, by combining NMR and mass spectrometry, we identified the dominant reaction products of the ZnSe formation reaction as oleylammonium chloride and amino-substitutions of TOP, i.e., iminophosphoranes (TOP=NR), aminophosphonium chloride salts [TOP(NHR)Cl], and bis(amino)phosphoranes [TOP(NHR)2]. Based on the acquired results, we outline a reaction scheme that involves the complexation of TOP=Se by ZnCl2, followed by the nucleophilic addition of oleylamine onto the Lewis acid activated P–Se bond, thereby eliminating ZnSe monomers and forming amino-substitutions of TOP. Our work highlights the central role of oleylamine, acting as both the nucleophile and Brønsted base, in the transformation of metal halides and alkylphosphine chalcogenides into metal chalcogenides.
Understanding the negative triangularity ELM trigger and ELM free state on DIII-D with ECE-imaging
Authors: Yu G. , Li Z. , Kramer G. , Scotti F. , Nelson A. O. , Diallo A. , Lasnier C. , Austin M. E. , Qin X. , Chen Y. , Zheng Y. , Zhu Y. , Luhmann N. C.
Published: June 2023

The Electron Cyclotron Emission Imaging (ECEI) diagnostic was used to observe a finite-n interchange mode structure in the edge of negative triangularity shaped plasmas on DIII-D. At a small negative triangularity (δu = −0.2), the plasma is in the H-mode with ELMs that are triggered by a low-n interchange mode. At a larger negative triangularity (δu = −0.4) and low NBI power (2 MW), a dithering oscillation is observed that is triggered by a low-n interchange mode, whereas at higher NBI power (>2 MW), the edge reverts to L-mode and the low-n interchange mode is present continuously. In all cases, the edge pressure gradient is clamped when the interchange mode is present. It is concluded that the low-n interchange mode prevents the plasma from transitioning to H-mode at a large negative triangularity. This agrees with linear BOUT++ simulations which suggest that the interchange-type MHD can be a resistive ballooning mode whereby resistivity can significantly increase the finite-n ballooning mode growth rate. The absence of H-mode at large negative triangularity can, thus, be explained by the excitation of low-n pressure driven resistive ballooning modes in the plasma edge.
Investigation on degree of non-ergodicity and local piezoelectric properties in Na0.5Bi0.5TiO3–BiFeO3–PbTiO3 system
Authors: Kuruvila Krupa Maria , Shvartsman V. V. , Hotari M. , Kiselev D. A. , Giridharan N. V.
Published: June 2023

Knowledge of the statics and dynamics of ferroelectric domains is of immense importance since they are directly correlated with macroscopic polarization and strain. For the present work, piezoresponse force microscopy (PFM) is used to afford insight into field-induced phase transitions and local switching properties of a (1–2x)Na0.5Bi0.5TiO3–xBiFeO3–xPbTiO3 system for compositions, x = 0.01, 0.03, 0.05, and 0.07. Rietveld analysis of x-ray diffraction data reveals crystallization of the compound in single and dual phases in the chosen compositions. Upon the application of a local electric field, a phase transition from relaxor to normal ferroelectric (FE) is observed for all samples. A decrease in degree of non-ergodicity is realized within this composition range, which is found by analyzing the stability of field-induced ferroelectric domains. The field-induced FE domains for lower concentrations of x are found to be irreversible and a reversible nature was found for higher values of x. In addition, spatial variations of local switching parameters are investigated with the help of switching spectroscopic-PFM and a maximum local d33 was found for compositions having dual phases.
Spin–orbit effects in cluster chemistry: Considerations and applications for rationalization of their properties
Authors: Muñoz-Castro Alvaro , Arratia-Perez Ramiro
Published: June 2023

Relativistic effects are usually taken into account in heavy-element-containing species, bringing to the scientific community stimulating cases of study. Scalar and spin–orbit effects are required to properly evaluate both the geometrical and electronic structures of such species, where, generally, scalar corrections are included. In order to take into account the spin–orbit term resulting from the interaction between the spatial and spin coordinates, double-valued point groups of symmetry are required, leading to total angular momenta (j) functions and atomic or molecular spinors, instead of pure orbital-angular momenta (l) and atomic or molecular orbitals. Here, we reviewed the role of spin–orbit coupling in bare and ligand-protected metallic clusters, from early to current works, leading to a more comprehensive relativistic quantum chemistry framework. As a result, the electronic structure is modified, leading to a variation in the calculated molecular properties, which usually improves the agreement between theory and experiment, allowing furthering rationalize of experimental results unexpected from a classical inorganic chemistry point of view. This review summarizes part of the modern application of spin–orbit coupling in heavy-elements cluster chemistry, where further treatment on an equal footing basis along with the periodic table is encouraged in order to incorporate such term in the general use vocabulary of both experimental and theoretical chemist and material scientist.
Accurate calculation of tunneling splittings in water clusters using path-integral based methods
Authors: Zhu Yu-Cheng , Yang Shuo , Zeng Jia-Xi , Fang Wei , Jiang Ling , Zhang Dong H. , Li Xin-Zheng
Published: June 2023

Tunneling splittings observed in molecular rovibrational spectra are significant evidence for tunneling motion of hydrogen nuclei in water clusters. Accurate calculations of the splitting sizes from first principles require a combination of high-quality inter-atomic interactions and rigorous methods to treat the nuclei with quantum mechanics. Many theoretical efforts have been made in recent decades. This Perspective focuses on two path-integral based tunneling splitting methods whose computational cost scales well with the system size, namely, the ring-polymer instanton method and the path-integral molecular dynamics (PIMD) method. From a simple derivation, we show that the former is a semiclassical approximation to the latter, despite that the two methods are derived very differently. Currently, the PIMD method is considered to be an ideal route to rigorously compute the ground-state tunneling splitting, while the instanton method sacrifices some accuracy for a significantly smaller computational cost. An application scenario of such a quantitatively rigorous calculation is to test and calibrate the potential energy surfaces of molecular systems by spectroscopic accuracy. Recent progress in water clusters is reviewed, and the current challenges are discussed.
Role of initial conditions in plasma-current coupling of gas-puff Z-pinches
Authors: Aybar N. , Conti F. , Narkis J. , Beg F. N.
Published: June 2023

Azimuthal magnetic field measurements obtained during the implosion phase of an oxygen gas-puff Z-pinch on a 500 kA peak current and 180 ns rise time linear transformer driver are presented. While a fraction of the driver current was measured within the imploding plasma, key initial conditions were found to significantly impact the delivery of current to the plasma load. The electrode geometry was modified to assist the initial dielectric breakdown and resulted in improved shot reproducibility. Optimization of the gas injection plenum pressure and timing resulted in an increase in the current coupling parameter, defined as the ratio of the measured value of Bθ to the expected value, from 50% to 75%. The degree of radial expansion of the gas puff in the load region, which is suspected to lead to the observed current loss during the implosion, was reduced by shortening the valve opening duration. Additionally, a pre-embedded axial magnetic field of up to 0.2 T was found to have no significant impact on the plasma-current coupling of the oxygen implosions.
Carbonized titanium dioxide with good adsorption properties for cationic dyes via simple heat treatment
Authors: Huang Maoliang , Wang Hongwei , Xiao Yue , Li Kang
Published: June 2023

With the development of modern industry, the discharge of dye wastewater is increasing year by year, and the damage caused by this wastewater to the ecosystem is often irreversible. Therefore, the research on the harmless treatment of dyes has attracted much attention in recent years. In this paper, commercial titanium dioxide (anatase nanometer titanium dioxide) was heat treated with anhydrous ethanol to synthesize titanium carbide (C/TiO2). Its maximum adsorption capacity for cationic dyes methylene blue (MB) and Rhodamine B is 27.3 and 124.6 mg g−1, respectively, which is much higher than that of pure TiO2. The adsorption kinetics and isotherm model of C/TiO2 were studied and characterized by Brunauer–Emmett–Teller, x-ray photoelectron spectroscopy, x-ray diffraction, Fourier transform infrared spectroscopy, and other methods. The results show that the carbon layer on the surface of C/TiO2 promotes the increase in surface hydroxyl groups, which is the main reason for the increase in MB adsorption. Compared with other adsorbents, C/TiO2 showed excellent reusability. The experimental results of adsorbent regeneration showed that the adsorption rate R% of MB was almost unchanged after three cycles. During the recovery of C/TiO2, the dyes adsorbed on its surface are removed, which solves the problem that the adsorbent cannot degrade dyes simply by adsorption. Additionally, C/TiO2 has a stable adsorption effect, is insensitive to the pH value, has a simple preparation process, and has relatively low raw material prices, making it suitable for large-scale operation. Therefore, it has good commercial prospects in the organic dye industry wastewater treatment.
Robustness of semimetallic transport properties of TaAs against off-stoichiometric disorder
Authors: Kawasuso A. , Suda M. , Murakawa H. , Komada M. , Suzuki C. , Amada H. , Michishio K. , Maekawa M. , Miyashita A. , Seko N. , Yamamoto S. , Oshima N. , Seki S. , Hanasaki N.
Published: June 2023

TaAs single crystals were grown by a standard chemical vapor transport method. The single-crystallinity and homogeneous distribution of elements were confirmed by transmission electron microscope and x-ray diffraction observations. Positron annihilation measurements revealed that the atomic vacancy concentration was kept below 10−5 at. %. However, inductively coupled plasma analysis showed an As-deficient (7–9 at. %) off-stoichiometry. First-principles calculations implied that the off-stoichiometry could be compensated for with excess Ta antisite defects, thereby inducing metallic states. Nevertheless, excellent semimetallic transport properties of a well-suppressed carrier density (≲1018 cm−3), ultrahigh carrier mobility (≳106 cm2/V/s), and large transverse magnetoresistance (>200000% at 9 T) with the quantum oscillation were obtained at 1.7 K. This indicated the robustness of semimetallic transport properties against the off-stoichiometric disorder and the quenching of metallic conduction associated with excess Ta atoms. The negative longitudinal magnetoresistance, which is considered evidence of a Weyl semimetal (chiral anomaly), was not observed. These data were discussed with theoretical calculations.
Nonadiabatic dynamics near metal surface with periodic drivings: A Floquet surface hopping algorithm
Authors: Wang Yu , Dou Wenjie
Published: June 2023

We develop a Floquet surface hopping approach to deal with nonadiabatic dynamics of molecules near metal surfaces subjected to time-periodic drivings from strong light–matter interactions. The method is based on a Floquet classical master equation (FCME) derived from a Floquet quantum master equation (FQME), followed by a Wigner transformation to treat nuclear motion classically. We then propose different trajectory surface hopping algorithms to solve the FCME. We find that a Floquet averaged surface hopping with electron density (FaSH-density) algorithm works the best as benchmarked with the FQME, capturing both the fast oscillations due to the driving and the correct steady-state observables. This method will be very useful to study strong light–matter interactions with a manifold of electronic states.
A new fault detection strategy for wind turbine rotor imbalance based on multi-condition vibration signal analysis
Authors: Wang Zekun , Xu Jin , Jia Yan , Cai Chang , Zhou Teng , Wang Xiaodong , Xu Jianzhong , Li Qing'an
Published: June 2023

Aiming at the problem that it is difficult to accurately detect the position and magnitude of pitch angle deviation (PAD) fault of wind turbine (WT) in operation at the same time, this paper proposes a novel multi-parameter synergy mechanism based on a double threshold judgment method combined with power spectral density analysis. First, the influence of different PADs of a single blade on the time domain information of WT parameters under different turbulent wind speeds is discussed. Second, according to the changing rule of three blade parameters caused by the single blade PAD, the double threshold judgment method is introduced to determine the faulty blade and the direction of PAD. Third, this paper put forward the concept of characteristic frequency power ratio. Based on the characteristic frequency of the power spectrum, a method is proposed to determine the magnitude of PAD. Finally, a complete set of fault detection and identification flow for single blade PAD was established. This detection strategy is more accurate and faster than the traditional methods and does not need to add additional data acquisition equipment in the wind power generation system.
Revised Enskog theory for Mie fluids: Prediction of diffusion coefficients, thermal diffusion coefficients, viscosities, and thermal conductivities
Authors: Jervell Vegard G. , Wilhelmsen Øivind
Published: June 2023

Since the 1920s, the Enskog solutions to the Boltzmann equation have provided a route to predicting the transport properties of dilute gas mixtures. At higher densities, predictions have been limited to gases of hard spheres. In this work, we present a revised Enskog theory for multicomponent mixtures of Mie fluids, where the Barker–Henderson perturbation theory is used to calculate the radial distribution function at contact. With parameters of the Mie-potentials regressed to equilibrium properties, the theory is fully predictive for transport properties. The presented framework offers a link between the Mie potential and transport properties at elevated densities, giving accurate predictions for real fluids. For mixtures of noble gases, diffusion coefficients from experiments are reproduced within ±4%. For hydrogen, the predicted self-diffusion coefficient is within 10% of experimental data up to 200 MPa and at temperatures above 171 K. Binary diffusion coefficients of the CO2/CH4 mixture from simulations are reproduced within 20% at pressures up to 14.7 MPa. Except for xenon in the vicinity of the critical point, the thermal conductivity of noble gases and their mixtures is reproduced within 10% of the experimental data. For other molecules than noble gases, the temperature dependence of the thermal conductivity is under-predicted, while the density dependence appears to be correctly predicted. Predictions of the viscosity are within ±10% of the experimental data for methane, nitrogen, and argon up to 300 bar, for temperatures ranging from 233 to 523 K. At pressures up to 500 bar and temperatures from 200 to 800 K, the predictions are within ±15% of the most accurate correlation for the viscosity of air. Comparing the theory to an extensive set of measurements of thermal diffusion ratios, we find that 49% of the model predictions are within ±20% of the reported measurements. The predicted thermal diffusion factor differs by less than 15% from the simulation results of Lennard-Jones mixtures, even at densities well exceeding the critical density.
A machine learning potential for simulating infrared spectra of nanosilicate clusters
Authors: Tang Zeyuan , Bromley Stefan T. , Hammer Bjørk
Published: June 2023

The use of machine learning (ML) in chemical physics has enabled the construction of interatomic potentials having the accuracy of ab initio methods and a computational cost comparable to that of classical force fields. Training an ML model requires an efficient method for the generation of training data. Here, we apply an accurate and efficient protocol to collect training data for constructing a neural network-based ML interatomic potential for nanosilicate clusters. Initial training data are taken from normal modes and farthest point sampling. Later on, the set of training data is extended via an active learning strategy in which new data are identified by the disagreement between an ensemble of ML models. The whole process is further accelerated by parallel sampling over structures. We use the ML model to run molecular dynamics simulations of nanosilicate clusters with various sizes, from which infrared spectra with anharmonicity included can be extracted. Such spectroscopic data are needed for understanding the properties of silicate dust grains in the interstellar medium and in circumstellar environments.
Thermal characterization of Ge-rich GST/TiN thin multilayers for phase change memories
Authors: Chassain Clément , Kusiak Andrzej , Gaborieau Cécile , Anguy Yannick , Tran Nguyet-Phuong , Sabbione Chiara , Cyrille Marie-Claire , Wiemer Claudia , Lamperti Alessio , Battaglia Jean-Luc
Published: June 2023

In the domain of phase change memories (PCMs), intensive research is conducted to reduce the programming cycle cost. The RESET operation is done by melting the PCM and then quenching the liquid phase to put it back to the amorphous state. In most of the devices, the heating is realized by the Joule effect with a titanium nitride (TiN) component put in contact with the PCM itself. One of the crucial points to improve the efficiency of this technology is to characterize the thermal contact between TiN and PCM. Having a low thermal resistance between the heater and the PCM ensures the heat transfer between the two is as efficient as possible. In this work, the interfacial thermal resistance between Ge-doped G2Sb2Te5 (GeGST)/TiN in multilayer systems has been characterized, and the influence of the compressive stress exerted by the TiN layers on the GeGST crystallization has been highlighted.
Huge perpendicular magnetic anisotropy in a 12-fold planar hypercoordinate W@B12(NCCN)3 monolayer
Authors: Xing Jianpei , Zhao Bo , Qu Xin , Jiang Xue , Zhao Jijun
Published: June 2023

Two-dimensional (2D) materials with planar hypercoordinate motifs are attractive in terms of both fundamental science and technological applications. Herein, we construct a stable hexagonal 2D W@B12(NCCN)3 monolayer using W@B12 cluster as a building block and –NCCN– as a bridge linker. Multi-center bonding analysis reveals that the abundant 3c–1e B–W–Β σ bonds are responsible for the stability of a 12-fold coordinated W@B12 wheel, which has the highest coordination number reported for a planar system. Moreover, 3c–1e Β−Ν−Β, 4c − 1e N–C–C–N, and 13c − 1e W–B12 π bonds together form big delocalized π bonds, endowing 2D W@B12(NCCN)3 with unusual stability. Remarkably, 2D W@B12(NCCN)3 is a robust ferromagnetic half-metal with a large orbital moment anisotropy of 1.3 μB, a high out-of-plane magnetic anisotropy energy of 199 meV/atom, and a high Curie temperature of 150 K, which provides a potential candidate for high-density memory devices. These findings provide vital guidance for the design of 2D magnets with planar hypercoordination and unusual functionality.
A physically realizable molecular motor driven by the Landauer blowtorch effect
Authors: Preston Riley J. , Kosov Daniel S.
Published: June 2023

We propose a model for a molecular motor in a molecular electronic junction driven by a natural manifestation of Landauer’s blowtorch effect. The effect emerges via the interplay of electronic friction and diffusion coefficients, each calculated quantum mechanically using nonequilibrium Green’s functions, within a semiclassical Langevin description of the rotational dynamics. The motor functionality is analyzed through numerical simulations where the rotations exhibit a directional preference according to the intrinsic geometry of the molecular configuration. The proposed mechanism for motor function is expected to be ubiquitous for a range of molecular geometries beyond the one examined here.
Exploring the distinct conformational preferences of allyl ethyl ether and allyl ethyl sulfide using rotational spectroscopy and computational chemistry
Authors: Poonia Tamanna , van Wijngaarden Jennifer
Published: June 2023

The conformational energy landscapes of allyl ethyl ether (AEE) and allyl ethyl sulfide (AES) were investigated using Fourier transform microwave spectroscopy in the frequency range of 5–23 GHz aided by density functional theory B3LYP-D3(BJ)/aug-cc-pVTZ calculations. The latter predicted highly competitive equilibria for both species, including 14 unique conformers of AEE and 12 for the sulfur analog AES within 14 kJ mol−1. The experimental rotational spectrum of AEE was dominated by transitions arising from its three lowest energy conformers, which differ in the arrangement of the allyl side chain, while in AES, transitions due to the two most stable forms, distinct in the orientation of the ethyl group, were observed. Splitting patterns attributed to methyl internal rotation were analyzed for AEE conformers I and II, and the corresponding V3 barriers were determined to be 12.172(55) and 12.373(32) kJ mol−1, respectively. The experimental ground state geometries of both AEE and AES were derived using the observed rotational spectra of the 13C and 34S isotopic species and are highly dependent on the electronic properties of the linking chalcogen (oxygen vs sulfur). The observed structures are consistent with a decrease in hybridization in the bridging atom from oxygen to sulfur. The molecular-level phenomena that drive the conformational preferences are rationalized through natural bond orbital and non-covalent interaction analyses. These show that interactions involving the lone pairs on the chalcogen atom with the organic side chains favor distinct geometries and energy orderings for the conformers of AEE and AES.