bluuebunny/crossref_metadata_2025 huggingface dataset:
Educational and digital tools as factors of service quality increase in Thailand 4.0 era (the case of Suvarnabhumi Airport, Bangkok)
Authors: Charernnit Kanittha
Published: December 2020

Currently, Thailand implemented the project Thailand 4.0 essentially highlighted on better performance on human resource as well as an information technology management. However, service quality is the key to create the business differentiation as well as to elevate a superior level of market competitiveness. The aviation industry is one of the most intense competitive industry, therefore, passengers’ satisfaction on airport service quality and its’ efficient facility management is the most important factor that can create business differentiation and influenced a sustainable industry accordingly. This paper seeks to investigate the (1) factors that affect service quality and (2) passengers’ satisfaction of Suvarnabhumi airport in Thailand 4.0 era. Where the concept of Importance-Performance Analysis (IPA) has been implemented in this research, the results show that passenger’s expectation on service quality was higher than the services that passengers received in many areas. However, from 150 questionnaires that have been released, the research results indicated that most of the respondents placed the highest satisfaction on the quality of internet and wireless connectivity service as the top priority at Suvarnabhumi Airport, whereas the lowest satisfaction is placed on the service quality of an immigration process where the effectiveness of human resources management is the key element affecting the service quality. Moreover, there is a recommendation on the self-check-in-counter and the processing of this service that needs to be modernized and promote passengers to use this technology widely. Hence, to enhance the airport service quality toward Thailand 4.0, the technology should be taken into account at every level to increase passengers’ satisfaction throughout the passenger’s arrival, departure and transit process accordingly.
Globalisation influence on higher education in Kazakhstan and Russia (on the example of Engineering University)
Authors: Sarsenbayeva A. , Makarikhina I.
Published: December 2020

Globalisation is a controversial issue in education in terms of its positive or negative impact. The given article presents the review of the existing literature with regard to the benefits that globalization brought to Kazakhstani and Russian higher education and some concerns arose. The authors of the article analyze such educational phenomena pluses as university autonomy, academic mobility, university rankings and English language proliferation. Substantial modernization of higher education content in accordance with the requirements of society and the state to the specialists’ education level, including foreign languages is necessary in the conditions of the economic, socio-political and social relations transformation. The revision of traditional paradigm in the general system of higher education is due to the objective need of society for an individual, aware and practically realizing his vocation and purpose in various types and international practice arising. Regarding the concerns that accompany the process of globalisation of higher education in Kazakhstan and Russia, the article considers and refutes the issues that come from the popularity of English language, the probability of colonization of Kazakhstani culture and brain drain.
Cross-border model of young personnel professional identity formation in Rostov region agro-industrial complex
Authors: Murzina Svetlana , Timofeev Sergey
Published: December 2020

The article is devoted to the study of statistical data on the number of students in the agro-industrial direction in the Rostov region, their demand in the labor market in the conditions of cross-border educational process. The transformation of the education system into a service sector makes self-identification with the profession more difficult. Changes also occur in the system of values and norms of new generations of professionals, whose professional identification formed in the transitive period of the educational space. The considered interdisciplinary approaches to the definition of identity revealed difficulties in the interpretation of this phenomenon in pedagogy, the variety of semantic approaches existed. All these changes lead to the development of a new adaptive model of behavior among students, lack of misunderstanding by educational actors of the essence of the ongoing reforms in the education field and, as a result, the emergence of ineffective educational institutions. If a person identifies himself within the profession that he engaged in, then the efficiency of work, its usefulness will be much higher. Identity as an aspect of motivation will help to remove professional tension, internal conflict. Based on the processing of statistical data, a hypothesis that they have a professional identity proposed. The authors of the article put forward proposals to improve the level of professional identity of young professionals on the base of cross-border model.
Using the capabilities of artificial intelligence in the development of reflection skills
Authors: Vysotskaya Polina , Zabelina Svetlana , Kuleshova Julia , Pinchuk Irina
Published: December 2020

The problems of developing of soft skills of people involved in educational activities are examined, their composition in the field of education is revealed. Special attention is paid to the formation of reflective skills using the capabilities of artificial intelligence, in particular Chatbots. A technique has been developed for implementing the reflective management of the student’s intellectual activity in the Chatbots system. Case scenaries are proposed that immerse the user in the problem space of the educational situation. The effectiveness of using the capabilities of artificial intelligence in the formation of reflective skill is proved.
Model of integration of competencies in a professionally-oriented education
Authors: Rozin Mikhail , Svechkarev Valery , Nesmeyanov Evgeny , Ryabtseva Irina , Yusov Sergey
Published: December 2020

It is noted that in higher professional education there is a global trend of the growing number of students combining the process of studying at the University with employment in the workplace in order to form a basis for their future professional and specialized career. Modern researches of the existing educational standards reveal the fact that there are practically no models meeting the needs of a new perspective on the organization of professionally-oriented training. It is suggested that the topological description on the basis of the graph theory, namely the cognitive model which has already been tested in the study of such problems in education should be used as a theoretical and methodological basis of the study. The cognitive model allows to involve the available model descriptions of educational processes, namely, structural-dynamic descriptions interpreted in this case as logical-semantic and causal. A multi-circuit cognitive model of professionally-oriented education based on the integration of competencies is proposed. The authors propose a multi-circuit cognitive model of professionally-oriented education based on the integration of competencies. The Central place in the model is given to the target chain of factors: Integration of competences → Professional competences → Educational and production process. This model helps transmit and synchronize signals across all model contours, continuously initialize the target model functioning, and analyze the achieved level of professional competencies in the integration process. It is on this axis that all four contours of the model are strung, which eliminates the loss of the target determination of the structure. The model implements the principle of professional orientation of education. Thus it is possible to balance the advantages of the educational competences received as a result of educational process, as well as the peculiarities of the production competences generated in manufacturing by means of their integration. Professional competencies in the model do not dominate, but rather are the result of continuous integration of both educational and industrial competencies.
Magnetoresistance investigation in the mixed state of a high temperature superconductor
Authors: Bghour Mustapha , Labrag Abdelaziz , El Hamidi Habiba , Abou El Hassan Ahmed , Taoufik Ahmed
Published: December 2020

In this work, we analyze the behavior of the magnetoresistance R (H, T) of a high temperature superconductor YBa
2
Cu
3
O
7−δ
thin film optimally doped. Measurements of the magnetoresistance were carried out in the mixed state for a magnetic field up to 14 T applied parallel to c − axis then parallel to ab − plane with a dc transport current of 100 and 500 nA, 0.1 and 0.3 mA perpendicular to the magnetic field direction in both cases. The obtained results show that the magnetoresistance is in a good agreement with the thermally assisted flux creep. However, the magnetoresistance in the flux flow regime cannot be described by the Barden-Stephen model which conjectures another origin of these results. In this sense, the quantum fluctuations of the order parameter is a good alternative to understanding the shape of the magnetoresistance. The comparison of the magnetoresistance of the two directions shows that [see formula in PDF] is larger than [see formula in PDF] with anisotropy factor [see formula in PDF] depending on temperature and magnetic field. The irreversibility line H

irr
 (T) as well as H

C2 (T) are determined and the first one is fitted with the phenomenological model H

irr
 (T) = H

irr
 (0) (1 − T/T

o
) 
α
where H

irr
 (0), T

o
and α are parameters obtained from the fit. The investigation of the scaling law allows us to prove that a crossover from 3D to 2D behavior is a feature of our sample which justifies the existence of the decoherence effect.
An investigation on thermodynamics and kinetics of η phase formation in Nb-modified iron-nickel base A286 superalloy
Authors: Gilakjani Reza Soleimani , Razavi Seyed Hossein , Seifollahi Masoumeh
Published: December 2020

In this study, precipitation of η phase (Ni3Ti) in conventional and Nb-modified (Nb-A286) A286 superalloys was evaluated at different aging times and temperatures. The TTP curve of the η phase formation was plotted using thermodynamic analyses, kinetics and microstructural studies. Depending on temperature and heat treatment, the η phase precipitated at the grain boundaries or twin sites, as a result of the γ′ phase or matrix austenite transformation. Heat treatment of conventional A286 superalloy and Nb-A286 was performed within a temperature range of 650 to 900 °C for 2 to 30 h. The η phase transformation was evaluated by scanning electron microscope (SEM) which is equipped to energy dispersive X-ray spectroscopy (EDS) and optical microscopy (OM). In the analyses based on thermodynamic calculations, the interaction of the Gibbs free energy of η phase formation and the diffusion activation energy of the elements, especially titanium and niobium, was considered. The microstructural studies showed that increasing the heat treatment time results in increasing the volume fraction of the η phase. By increasing the aging temperature to 840 and 860 °C for conventional A286 superalloy and Nb-A286 superalloy, respectively, the η phase volume fraction increased, however, further increase led to volume fraction decrease. The results of the thermodynamic analyses showed the tip of the TTP diagrams at temperatures of 860 and 820 °C for the A286 and Nb-A286 alloys, respectively. Investigation of kinetics calculations showed that η phase transformation depends on the diffusion of titanium, nickel, and niobium.
Return to Sport bei Knorpelverletzungen – Bericht zum 7. Jahreskongress des OSINSTITUTs
Authors: Overlöp Denis , Bauer Natascha
Published: December 2020

Der „Return to Sport“-Prozess stellt Fachkräfte unterschiedlicher Disziplinen vor große Herausforderungen. PD Dr. med. Götz H. Welsch, leitender Mannschaftsarzt des HSV, und Bernhard Peters, ehemaliger Sportdirektor der TSG 1899 Hoffenheim und des HSV, stellten sich diesem Thema beim 7. Jahreskongress des OSINSTITUTs. Passend zum Thema der Veranstaltung „Prehab und Rehab – der Knorpel im Fokus“ lieferte Dr. med. Christina Valle, Fachärztin für Physikalische Medizin und Rehabilitation, Evidenz und Tipps rund um das Thema Ernährung und Knorpel.
Kryotherapie: Praxis, Theorie und die Evidenzlage
Authors: Hohenauer Erich , Clijsen Ron , Clarys Peter
Published: December 2020

Behandlungsparadigmen sollten in der Sportphysiotherapie regelmäßig aktualisiert werden, basierend auf dem aktuellen Stand der Forschungsergebnisse. Das gilt insbesondere auch für den Einsatz von Kälte im Sport.
Bekleidung bei Sport in der Kälte
Authors: Annaheim Simon
Published: December 2020

Wer bei Kälte Sport treibt, weiß, wie schwierig es ist, die richtige Kleidung zu wählen: Die Bekleidung soll einerseits vor Kälte, Nässe und Wind schützen, andererseits sollte sie einen hohen Tragekomfort bieten, auch bei körperlicher Aktivität. Die ganz unterschiedlichen und teils sogar gegenläufigen Anforderungen können dank mehreren Schichten erfüllt werden. Jede davon hat eine andere Funktion - und jede Aktivität stellt andere Anforderungen an sie.
Risk of colonoscopy-related complications in a fecal immunochemical test-based population colorectal cancer screening program
Authors: Hsu Wen-Feng , Chang Chi-Yang , Chang Chun-Chao , Chang Li-Chun , Chen Chien-Hua , Lin Chun-Che , Lin Yu-Min , Lee Chia-Long , Wu Hong-Yuan , Lee Hsin-Chung , Lee Yi-Chia , Su Ming-Yao , Lin Li-Ju , Chia Shu-Li , Wu Ming-Shiang , Chiu Han-Mo ,   for the Colonoscopy Quality Assurance Joint Working Group of Taiwan Colorectal Cancer Screening Program and Digestive Endoscopy Society of Taiwan
Published: December 2020

Background The likelihood of advanced or synchronous neoplasms is significantly higher in fecal immunochemical test (FIT)-positive individuals than in the general population. The magnitude of the colonoscopy-related complication rate in FIT-positive individuals remains unknown. This study aimed to elucidate the colonoscopy-related complication rate after a positive FIT result and compare it with the rate when colonoscopy was performed for other purposes.

Methods Information regarding colonoscopy-related severe complications after a positive FIT result (FIT-colonoscopy) and ordinary colonoscopy during 2010–2014 was collected from the Taiwanese Colorectal Cancer Screening Program Database and National Health Insurance Research Database. Severe complications included significant bleeding, perforation, and cardiopulmonary events ≤ 14 days after colonoscopy. The number of events per 1000 procedures was used to quantify complication rates. Multivariate analysis was conducted to assess the association of various factors with severe complications associated with FIT-colonoscopy compared with ordinary colonoscopy.

Results 319 114 FIT-colonoscopies (214 955 patients) were identified, 51 242 (16.1 %) of which included biopsy and 94 172 (29.5 %) included polypectomy. Overall, 2125 significant bleedings (6.7 ‰) and 277 perforations (0.9 ‰) occurred ≤ 14 days after FIT-colonoscopy. Polypectomy, antiplatelet use, and anticoagulant use were associated with higher risk of complications (adjusted odds ratio [aOR] 4.41, 95 % confidence interval [CI] 4.05–4.81); aOR 1.35, 95 %CI 1.12–1.53; aOR 1.88, 95 %CI 0.61–5.84, respectively). Compared with ordinary colonoscopy, FIT-colonoscopy involved significantly higher risk of significant bleeding (aOR 3.10, 95 %CI 2.90–3.32).

Conclusions FIT-colonoscopy was associated with a more than two-fold risk of significant bleeding, especially when polypectomy was performed.
Image of the Month: Decision-Making in Surgery for Late Onset Hirschsprung Disease
Authors: Apte Anisha , McKenna Elise , Levitt Marc A.
Published: December 2020

We present a case of a 14-year-old boy with chronic distension, poor growth, and chronic constipation. He undergoes anorectal manometry and rectal biopsy, confirming the diagnosis of Hirschsprung disease (HD). The case is presented with a key image and associated questions to prompt discussion on strategies for management and treatment of HD in late-diagnosed children.
Neonatal Survivability following Previable PPROM after Hospital Readmission for Intervention
Authors: LeMoine Felicia , Moore Robert C. , Chapple Andrew , Moore Ferney A. , Sutton Elizabeth
Published: December 2020

Objective To describe our hospital's experience following expectant management of previable preterm prelabor rupture of membranes (pPPROM).

Study Design Retrospective review of neonatal survival and maternal and neonatal outcomes of pPPROM cases between 2012 and 2019 at a tertiary referral center in South Central Louisiana. Regression analyses were performed to identify predictors of neonatal survival.

Results Of 81 cases of pPPROM prior to 23 weeks gestational age (WGA), 23 survived to neonatal intensive care unit discharge (28.3%) with gestational age at rupture ranging from 180/7 to 226/7 WGA. Increased latency (adjusted odds ratio [aOR] = 1.30, 95% confidence interval [CI] = 1.11, 1.52) and increased gestational age at rupture (aOR = 1.62, 95% CI = 1.19, 2.21) increased the probability of neonatal survival. Antibiotics prior to delivery were associated with increased latency duration (adjusted hazard ratio = 0.55, 95% CI = 0.42, 0.74).

Conclusion Neonatal survival rate following pPPROM was 28.3%. Later gestational age at membrane rupture and increased latency periods are associated with increased neonatal survivability. Antibiotic administration following pPPROM increased latency duration.
Investigating electrostatic pigment-protein interactions and energy transfer
Authors: McConnon Aili
Published: December 2020

A multiscale study details the intra- and intermonomer energy transfer process in FMO proteins.
Arbitrary manipulations of dual harmonics and their wave behaviors based on space-time-coding digital metasurface
Authors: Dai Jun Yan , Yang Jin , Tang Wankai , Chen Ming Zheng , Ke Jun Chen , Cheng Qiang , Jin Shi , Cui Tie Jun
Published: December 2020

Metasurfaces have developed rapidly in the past decade because their customizable properties are able to regulate wave-matter interaction over a subwavelength scale. Recently, the space-time modulated metasurfaces have attracted significant attention for the additional degree of freedom they offer in the manipulation of the electromagnetic waves in both space and time domains. However, the existing techniques have limited wave control capabilities, which results in just a few feasible schemes, like regulation of only one specific harmonic. Here, we propose to create independent manipulations of arbitrary dual harmonics and their wave behaviors using a space-time-coding digital metasurface. By employing different space-time-coding sequences in the reflection phase of the metasurface, independent phase-pattern configurations of two desired harmonics can be achieved simultaneously, which further leads to independent beam shaping at the two harmonic frequencies. We have developed an analytical theory to offer physical insights into the arbitrary dual-harmonic manipulations of spectra and spatial beams, which is verified by experiments with good agreements. The presented space-time-coding strategy provides a new way to design multifunctional programable systems, which will find potential applications such as cognitive radar and multi-user wireless communications.
Matching conflicting oxidation conditions and strain accommodation in perovskite epitaxial thin-film ferroelectric varactors
Authors: Zeinar Lukas , Salg Patrick , Walk Dominik , Petzold Stefan , Arzumanov Alexey , Jakoby Rolf , Maune Holger , Alff Lambert , Komissinskiy Philipp
Published: December 2020

Perovskite oxide materials of the general chemical formula ABO3 are a rich playground for epitaxial stacks of different functional layers for novel device applications. In the example of a tunable metal–insulator–metal ferroelectric varactor (tunable capacitor) made from the highest conducting perovskite SrMoO3 as an electrode and the tunable dielectric Ba0.5Sr0.5TiO3 (BST), we show how the extremely conflicting oxidation potentials can be conciliated in a fully functional heterostructure. Controlling the growth kinetics by the substrate temperature, oxygen pressure, and oxidation time, the formation of the non-conducting Mo6+ states can be effectively suppressed and the BST cation stoichiometry can be tuned. The cumulative impact of the cation nonstoichiometry, epitaxial strain, and oxygen deficiency in the BST films leads to the expansion of their c-axis lattice parameter via the formation of point defects. The dielectric permittivity of 440, the high tunability of 3.5, and the quality factor of 50 are achieved for the varactors at the frequency of 1 GHz. It turns out that the varactor performance is anti-correlated to the tetragonal lattice distortion of BST, which itself is interrelated to the oxidation conditions. The mechanism of the leakage current through oxygen deficient BST layers of the varactors is analyzed within the combined scenarios of the space-charge limited current and Poole–Frenkel field-assisted emission from traps. The achieved high capacitance per unit area of 0.04 pF/μm2 and moderate leakage currents of 0.025 μA/pF make these varactors suitable for applications in microwave microelectronic devices.
Fan-out and fan-in properties of superconducting neuromorphic circuits
Authors: Schneider M. L. , Segall K.
Published: December 2020

Neuromorphic computing has the potential to further the success of software-based artificial neural networks (ANNs) by designing hardware from a different perspective. Current research in neuromorphic hardware targets dramatic improvements to ANN performance by increasing energy efficiency and speed of operation and even seeks to extend the utility of ANNs by natively adding functionality such as spiking operation. One promising neuromorphic hardware platform is based on superconductive electronics, which has the potential to incorporate all of these advantages at the device level in addition to offering the potential of near lossless communications both within the neuromorphic circuits and between disparate superconductive chips. Here, we explore one of the fundamental brain-inspired architecture components, the fan-in and fan-out as realized in superconductive circuits based on Josephson junctions. From our calculations and WRSPICE simulations, we find that the fan-out should be limited only by junction count and circuit size limitations, and we demonstrate results in simulation at a level of 1-to-10 000, similar to that of the human brain. We find that fan-in has more limitations, but a fan-in level on the order of a few 100-to-1 should be achievable based on current technology. We discuss our findings and the critical parameters that set the limits on fan-in and fan-out in the context of superconductive neuromorphic circuits.
Exploring dynamical complexity in a time-delayed tumor-immune model
Authors: Das Parthasakha , Upadhyay Ranjit Kumar , Das Pritha , Ghosh Dibakar
Published: December 2020

The analysis of dynamical complexity in nonlinear phenomena is an effective tool to quantify the level of their structural disorder. In particular, a mathematical model of tumor-immune interactions can provide insight into cancer biology. Here, we present and explore the aspects of dynamical complexity, exhibited by a time-delayed tumor-immune model that describes the proliferation and survival of tumor cells under immune surveillance, governed by activated immune-effector cells, host cells, and concentrated interleukin-2. We show that by employing bifurcation analyses in different parametric regimes and the 0–1 test for chaoticity, the onset of chaos in the system can be predicted and also manifested by the emergence of multi-periodicity. This is further verified by studying one- and two-parameter bifurcation diagrams for different dynamical regimes of the system. Furthermore, we quantify the asymptotic behavior of the system by means of weighted recurrence entropy. This helps us to identify a resemblance between its dynamics and emergence of complexity. We find that the complexity in the model might indicate the phenomena of long-term cancer relapse, which provides evidence that incorporating time-delay in the effect of interleukin in the tumor model enhances remarkably the dynamical complexity of the tumor-immune interplay.
Influence of aspect ratio on vortex formation in X-junctions: Direct numerical simulations and eigenmode decomposition
Authors: Correa P. G. , Gomba J. M. , Mac Intyre J. R. , Ubal S. , Perazzo C. A. , Hulin J. P. , Auradou H.
Published: December 2020

We study numerically the appearance and number of axial vortices in the outlets of X-shaped junctions of two perpendicular channels of rectangular sections with facing inlets. We explore the effect of the aspect ratio of the cross section, AR, on the number of vortices created at the center of the junction. Direct numerical simulations (DNSs) performed for different values of the Reynolds number Re and AR demonstrate that vortices with their axis parallel to the outlets, referred to as axial vortices, appear above critical Reynolds numbers Rec. As AR increases from 1 to 11, the number of vortices observed increases from 1 to 4, independently of Re. For AR = 1, the single axial vortex induces an interpenetration of the inlet fluids in the whole section; instead, for larger AR’s for which more vortices appear, the two inlet fluids remain largely segregated in bands, except close to the vortices. The linear stability analysis demonstrates that only one leading eigenmode is unstable for a given set of values of AR and Re. This mode provides a simplified model of the flow field, reproducing its key features such as the number of vortices and their distance. Its determination with this method requires a much smaller computational load than the DNS. This approach is shown to allow one to determine quickly and precisely the critical Reynolds number Rec and the sensitivity function S, which characterizes the influence of variations of the base flow on the unstable one.
Prediction of crystalline Ta4O9 phase using first principles-based cluster expansion calculations
Authors: Pedersen Christian Søndergaard , Chang Jin Hyun , Li Yang , Pryds Nini , Garcia Lastra Juan Maria
Published: December 2020

Tantalum is the only element of Group 5 in the periodic table that lacks any experimental reports on the existence of reduced crystalline oxide between the pentoxide (Ta2O5) and the dioxide (TaO2). We computationally predict the existence of a novel tantalum oxide with Ta4O9 stoichiometry, which lies at the midpoint between Ta2O5 and TaO2. The ground-state Ta4O9 structure was found through simulated annealing based on a cluster expansion model, which is trained using 186 density functional theory calculations. The newfound Ta4O9 material has space group number 10 (P2/m), and it can be viewed as an oxygen-deficient λ-Ta2O5 structure in which oxygen vacancies aggregate pair-wise in nearest-neighbor sites. Tad–Tad bonds fill the spatial void of the oxygen vacancies, keeping the system non-magnetic and non-metallic. The synthesis of the new Ta4O9 crystal is deemed feasible through a controlled reduction of λ-Ta2O5. The reported Ta4O9 has the potential to open new avenues in catalysis and resistive switching device applications where the reduced tantalum oxides are broadly employed.
Control of pH in bioelectronics and applications
Authors: Jia Manping , Ray Sanhita , Breault Raymond , Rolandi Marco
Published: December 2020

Ions and biomolecules are the languages that biological systems use to transfer signals in intracellular communication and organism function. As such, bioelectronic devices that conduct ions and biomolecules rather than electrons and holes are particularly suited for biological integration. Among these ions, protons (H+) are important in many biochemical reactions including neuronal excitability and oxidative phosphorylation of adenosine triphosphate (ATP). In this Research Update, we describe our efforts in measuring and controlling the concentration of H+ ions in biological systems using bioelectronic devices with contacts that are made of palladium and palladium hydride (Pd/PdHx). Pd/PdHx contacts act as an electron to proton transducer and can be used in artificial membranes containing ion channels, biohybrid photodetectors, the delivery of biochemical stimuli, pH sensitive glucose sensing, and precise control of pH using machine learning.
Unsteady flow fluctuations in a centrifugal pump measured by laser Doppler anemometry and pressure pulsation
Authors: Zhang Ning , Zheng Fankun , Liu Xiaokai , Gao Bo , Li Guoping
Published: December 2020

Turbulent flow generated by the intense rotor–stator interaction is detrimental to the safe running of the centrifugal pump. In order to gain more insight into unsteady velocity pulsation characteristics, this research applies the laser Doppler anemometry technique to capture velocity signals at various flow rates. Besides, pressure transducers are arranged on the model pump to sample transient pressure pulsation signals. The study paid particular attention to pulsation signals in the diffusion section of the volute. Results show that at low flow rates, a prominent hump phenomenon generated within the pump head curve, which indicates the development of rotating stall in the model pump. As noted from the spectra, the discrete blade passing frequency and impeller rotating frequency dominate the velocity and pressure spectra. Root mean square values of velocity signals increase rapidly at off-design flow rates, especially within the rotating stall region, and a similar trend is observed for pressure amplitude at the blade passing frequency. From the measuring point (P3) at the inlet of the discharge channel upstream of the volute tongue to the point (P10) at the volute outlet, pressure amplitude rises significantly. Meanwhile, the minimum point of pressure amplitude vs flow rate occurs around 0.4ΦN, and again, the findings show differences for comparisons between measuring points in the core flow region of the volute. This resulting phenomenon can be attributed to flow patterns in the diffusion section.
Direct interception or inertial impaction? A theoretical derivation of the efficiency power law for a simple and practical definition of capture modes
Authors: Boudina Mouad , Gosselin Frédérick P. , Étienne Stéphane
Published: December 2020

We study the capture of particles advected by flows around a fixed cylinder. We derive theoretically the power law of the capture efficiency, usually obtained from data fitting only. Simulations of particle trajectories reveal that captured particles following the power law are smaller than the boundary layer of the cylinder and experience direct interception, whereas the ones diverging from it are larger and observe inertial impaction. We show that a simple comparison between the particle size and boundary layer thickness splits accurately numerical results into their dominant capture mode. This criterion is practical in experiments and simulations and would lift the controversy on the scaling of the capture efficiency.
Coarse-grained conformational surface hopping: Methodology and transferability
Authors: Rudzinski Joseph F. , Bereau Tristan
Published: December 2020

Coarse-grained (CG) conformational surface hopping (SH) adapts the concept of multisurface dynamics, initially developed to describe electronic transitions in chemical reactions, to accurately describe classical molecular dynamics at a reduced level. The SH scheme couples distinct conformational basins (states), each described by its own force field (surface), resulting in a significant improvement of the approximation to the many-body potential of mean force [T. Bereau and J. F. Rudzinski, Phys. Rev. Lett. 121, 256002 (2018)]. The present study first describes CG SH in more detail, through both a toy model and a three-bead model of hexane. We further extend the methodology to non-bonded interactions and report its impact on liquid properties. Finally, we investigate the transferability of the surfaces to distinct systems and thermodynamic state points, through a simple tuning of the state probabilities. In particular, applications to variations in temperature and chemical composition show good agreement with reference atomistic calculations, introducing a promising “weak-transferability regime,” where CG force fields can be shared across thermodynamic and chemical neighborhoods.
Pressure-driven flows of a thixotropic viscoplastic material: Performance of a novel fluidity-based constitutive model
Authors: Cunha J. P. , de Souza Mendes P. R. , Siqueira I. R.
Published: December 2020

This paper examines pressure-driven tube flows of inelastic yield-stress materials with thixotropic effects. In contrast to previous works based on structural kinetic models, we employ a fluidity-based constitutive model that uses the material fluidity as a measure of the material structuring level. The model relies on rheological material properties that can be determined from standard experimental tests, avoiding the introduction of phenomenological functions to describe the mechanisms of microstructure buildup and breakdown in the flow. We analyze the transient evolution of velocity and fluidity fields toward the steady-state condition as functions of the material initial structuring state and the plastic number, a dimensionless parameter that measures the intensity of the material plasticity. When the material is initially fully structured, the results show that the avalanche effect essentially depends on the applied pressure gradient. Likewise, the process of microstructure buildup when the material is initially fully unstructured is a strong function of the applied stress. The yield surface might split the flow into two regions where the microstructure builds up at different rates, leading to a discontinuity in the transient evolution of fluidity and shear rate fields similar to that associated with transient shear banding. Finally, we show that the steady-state flow is determined by the imposed pressure gradient only and does not depend on the material initial structuring condition. These predictions bring new insights to fundamentally understand the flow of thixotropic viscoplastic materials and then optimize the operating conditions of processing flows of structured materials in many applications.
Extension at the downstream end of turbulent band in channel flow
Authors: Liu Jinsheng , Xiao Yue , Zhang Linsen , Li Mogeng , Tao Jianjun , Xu Shengjin
Published: December 2020

In this Letter, the velocity structures and the extension behavior of localized turbulent bands in channel flows are measured by particle image velocimetry in a plane parallel to the walls and are analyzed by comparing with direct numerical simulations at low Reynolds numbers. It is illustrated that the convection velocity of the band head (band’s downstream end) is not determined by the formation and propagation of low-speed streaks but by a high-speed “hat” shaped region near the band head. This “hat” region travels downstream obliquely like a solitary wave and leaves newly generated low-speed streaks to travel slowly in the spanwise direction, leading to the head extension of turbulent bands.
Analytical solution for an acoustic boundary layer around an oscillating rigid sphere
Authors: Klaseboer Evert , Sun Qiang , Chan Derek Y. C.
Published: December 2020

Analytical solutions in fluid dynamics can be used to elucidate the physics of complex flows and to serve as test cases for numerical models. In this work, we present the analytical solution for the acoustic boundary layer that develops around a rigid sphere executing small amplitude harmonic rectilinear motion in a compressible fluid. The mathematical framework that describes the primary flow is identical to that of wave propagation in linearly elastic solids, with the difference being the appearance of complex instead of real valued wave numbers. The solution reverts to the well-known classical solutions in special limits: the potential flow solution in the thin boundary layer limit, the oscillatory flat plate solution in the limit of large sphere radius, and the Stokes flow solutions in the incompressible limit of infinite sound speed. As a companion analytical result, the steady second order acoustic streaming flow is obtained. This streaming flow is driven by the Reynolds stress tensor that arises from the axisymmetric first order primary flow around such a rigid sphere. These results are obtained with a linearization of the non-linear Navier–Stokes equations valid for small amplitude oscillations of the sphere. The streaming flow obeys a time-averaged Stokes equation with a body force given by the Nyborg model in which the above-mentioned primary flow in a compressible Newtonian fluid is used to estimate the time-averaged body force. Numerical results are presented to explore different regimes of the complex transverse and longitudinal wave numbers that characterize the primary flow.
High detection efficiency silicon single-photon detector with a monolithic integrated circuit of active quenching and active reset
Authors: Fang Yu-Qiang , Luo Kai , Gao Xing-Guo , Huo Gai-Qing , Zhong Ang , Liao Peng-Fei , Pu Pu , Bao Xiao-Hui , Chen Yu-Ao , Zhang Jun , Pan Jian-Wei
Published: December 2020

Silicon single-photon detectors (SPDs) are key devices for detecting single photons in the visible wavelength range. Photon detection efficiency (PDE) is one of the most important parameters of silicon SPDs, and increasing PDE is highly required for many applications. Here, we present a practical approach to increase the PDE of silicon SPDs with a monolithic integrated circuit of active quenching and active reset (AQAR). The AQAR integrated circuit is specifically designed for thick silicon single-photon avalanche diodes (SPADs) with high breakdown voltage (250 V–450 V) and then fabricated via the process of high-voltage 0.35-μm bipolar-CMOS-DMOS. The AQAR integrated circuit implements the maximum transition voltage of ∼68 V with 30 ns quenching time and 10 ns reset time, which can easily boost PDE to the upper limit by regulating the excess bias up to a high enough level. By using the AQAR integrated circuit, we design and characterize two SPDs with the SPADs disassembled from commercial products of single-photon counting modules (SPCMs). Compared with the original SPCMs, the PDE values are increased from 68.3% to 73.7% and 69.5% to 75.1% at 785 nm, respectively, with moderate increases in dark count rate and afterpulse probability. Our approach can effectively improve the performance of the practical applications requiring silicon SPDs.
COVID-19 lockdown induces disease-mitigating structural changes in mobility networks
Authors: Schlosser Frank , Maier Benjamin F. , Jack Olivia , Hinrichs David , Zachariae Adrian , Brockmann Dirk
Published: December 2020

Significance

During the COVID-19 pandemic, mobility restrictions have proved to be an effective mitigation strategy in many countries. To apply these measures more efficiently in the future, it is important to understand their effects in detail. In this study, we use mobile phone data to uncover profound structural changes in mobility in Germany during the pandemic. We find that a strong reduction of long-distance travel rendered mobility to be more local, such that distant parts of the country became less connected. We demonstrate that due to this loss of connectivity, infectious diseases can be slowed down in their spatial spread. Our study provides important insights into the complex effects of mobility restrictions for policymakers and future research.
Face masks considerably reduce COVID-19 cases in Germany
Authors: Mitze Timo , Kosfeld Reinhold , Rode Johannes , Wälde Klaus
Published: December 2020

Significance

Mitigating the spread of COVID-19 is the objective of most governments. It is of utmost importance to understand how effective various public health measures are. We study the effectiveness of face masks. We employ public regional data about reported severe acute respiratory syndrome coronavirus 2 infections for Germany. As face masks became mandatory at different points in time across German regions, we can compare the rise in infections in regions with masks and regions without masks. Weighing various estimates, we conclude that 20 d after becoming mandatory face masks have reduced the number of new infections by around 45%. As economic costs are close to zero compared to other public health measures, masks seem to be a cost-effective means to combat COVID-19.
Defining linguistic reasoning
Authors: Dielemans Roy , Coppen Peter-Arno
Published: December 2020

Until recently, throughout the world, linguistic theory was virtually absent in secondary education, mostly limited to
grammar teaching still based on 19th century linguistic theory. There is a growing call, however, for enriching grammar teaching with modern
linguistic insights, integrating higher order critical thinking skills, like reasoning. This study tries to lay the groundwork for a model
of linguistic reasoning in particular.

Based on a well-established model for historical reasoning (Van Boxtel & Van Drie,
2018), a linguistic model is developed in two steps. First, the components of the historical model are theoretically analysed and
transposed to the linguistic domain, and second, the model is applied in qualitative analysis of linguistic experts’ reasoning.

It is found that the model fits linguistic reasoning fairy well: all central components can be observed, and are evenly
distributed over different experts. It is concluded that the linguistic reasoning model can be used in the development of a new grammar
pedagogy.
A brief review of metastable high-entropy alloys with transformation-induced plasticity
Authors: Yu Haoyang , Zhang Jinfei , Fang Wei , Chang Ruobin , Bai Xi , Yan Jiaohui , Zhang Xin , Liu Baoxi , Yin Fuxing
Published: December 2020

In metastable high-entropy alloys (HEAs), the decrease of phase stability enables the development of dual-phase microstructure (interface hardening) and occurrence of strain-induced martensitic transformation (transformation-induced hardening), which overcomes the strength–ductility trade-off. The stacking-fault energy (SFE) is closely related to the phase stability and plays a key role in controlling the underlying deformation mechanism and hence the mechanical performance of HEAs. Here, we review some approaches of SFE calculation, including theoretical and experimental methods as well as the factors affecting SFE. Several compositional systems related to metastable HEAs are also briefly reviewed. Furthermore, we show the unique microstructure and the structure–property relationship of the metastable HEAs. Furthermore, some potential research topics in the future are also proposed.
Microstructural evolution of a nickel-base single-crystal superalloy during high-temperature homogenisation
Authors: Li Xiangwei , Ding Rengen , Wen Donghui , Wang Yao , Chu Mingqiang , Wang Li , Zhang Peng , Zhang Shuyan
Published: December 2020

Microstructural evolution of a nickel-base single-crystal superalloy during homogenisation at ultra-high temperature has been investigated using scanning electron microscope and electron probe microanalyzer. The results show that incipient melting occurs and all γ/γ′ eutectics are re-melted into liquid after 1 h homogenisation at 1350°C. The volume fraction of IM decreases gradually with increasing homogenisation time. The IM disappears totally after 14 h homogenisation. Moreover, the formation of the TCP phase is suppressed during long-term thermal exposure at 1100°C for the reduction of element segregation, especially the segregation of refractory element Re was reduced during ultra-high-temperature homogenisation. The microstructure evolution of IM was discussed based on the element diffusion during homogenisation.
Differences in service-exposed and artificially aged microstructure and tensile properties of ASTM A204 Grade C steel
Authors: Sharma Nitin Kumar , Li Leijun , Wang Yajing , Dev Choudhury Suvan , Suzuk Yasin , Garcia Maria Marilin
Published: December 2020

Microstructural characterisation of artificially aged and service-exposed ASTM A204 Grade C steel reveals changes in the cementite particles of pearlite and microstructure. The ageing temperatures were chosen to be high enough to replicate the service degradation but below Ac1 to avoid austenitisation in the inter-critical regime. Tensile testing of artificially aged materials shows a decrease in the ultimate tensile strength (UTS) along with an increase in elongation. On the other hand, service-exposed material resulted in an increase in UTS and a decrease in elongation. The softening of pearlite due to spheroidisation of cementite and segregation of alloying elements towards grain boundaries were responsible for the lower UTS of the artificially aged samples. Whereas, the increase in UTS in the service-exposed sample was attributed to the formation of nano-sized carbides inside ferrite grains, hence strengthening the steel matrix.
Effect of solution treatment on micropore and mechanical properties of DD6 superalloy
Authors: Kang Maodong , Wang Jun , Xiong Wei , Sridar Soumya , Yu Junwei
Published: December 2020

Effect of solution treatment on the micropore and mechanical properties is investigated for the DD6 superalloy. The results show that solution treatment has positive and negative effects on the DD6 superalloy, which can weaken the segregation significantly. After solution treatment, the segregation ratio of the major alloying elements tends to 1. However, the amount of micropores increases with increasing solutionising time and can reach 0.46%, which is one order of magnitude higher than that of the as-cast superalloy. The hardness increases slightly, especially for the superalloy solutionised at 1310°C with a 5% increase in hardness compared to the as-cast superalloy. Hardness, tensile and stress rupture properties of the DD6 superalloy can reach the best after solution treatment at 1310°C and 4 h.
Effect of atmosphere on the microstructure and properties of additively manufactured tungsten
Authors: Dong Jing , Liu Shichao , Chen Hui , Li Dan , Zhang Taomei , Chen Chao , Zhou Kechao
Published: December 2020

The working atmosphere greatly affects the melting and solidification processes in powder-based additive manufacturing. In this work, pure tungsten components were fabricated by selective laser melting (SLM) under argon and nitrogen, respectively. The effects of the atmosphere and processing parameters on densiﬁcation, microstructures, and phases were investigated. Tungsten processed under nitrogen exhibited a higher density, lower roughness, and superior mechanical performance than that processed under argon. The high dynamic viscosity of liquid tungsten in argon induced balling and pore formation during the laser melting process, leading to relatively low density and poor mechanical properties of the SLM-processed tungsten that was manufactured in argon. The results help to promote the practical application of SLM for complicated tungsten components in the nuclear and military industries.
Effects of annealing temperature on microstructure and mechanical properties of LZ91 alloy
Authors: Yang Yan , Li Minmin , Deng Hongju , Ren Fengjuan , Zhang Hanzhu , Jiang Bin , Peng Xiaodong , Pan Fusheng
Published: December 2020

Effects of annealing temperature on the microstructure and mechanical properties of cold-rolled LZ91 alloy are investigated. The results indicate that LZ91 alloy is composed of α-Mg, β-Li, MgLiZn and MgLi2Zn phases. The recrystallization of the cold-rolled alloy is completed when annealing at 125°C and a large number of fine equiaxed grains with an average grain size of 3 µm is formed. The cold-rolled LZ91 alloys annealed at 125°C have the optimized comprehensive mechanical properties with the elongation, ultimate tensile strength and microhardness of 56.1%, 157 MPa and 51.2 HV, respectively. With the further increase in annealing temperature, the grain size begins to coarsen, which leads to the decrease in strength and ductility of the alloy.