bluuebunny/crossref_metadata_2025 huggingface dataset:
Heat source modeling, penetration analysis and parametric optimization of super spray MAG welding
Authors: Li Zhifeng , Xia Yimin
Published: June 2023

Main drives, cutterheads and other critical components of tunnel shield machines require welding with thick plates that leave roots over 5 mm. Full penetration welds cannot be achieved by conventional Pulsed MAG welding methods. This article introduces Super Spray MAG Welding technology and investigates its penetrating regularities and mechanisms through high-speed camera images, finite element simulation, and microstructural analysis. An optimal welding procedure was generated using a combination of Genetic Algorithm and Back Propagation Neural Network. The data show that Super Spray MAG arc exhibits greater concentration and stability than traditional MAG arc, marking its strong qualities in emitting high-energy beams. The morphological solidification pattern of the molten pool closely matches the FEM simulation results of the composite Gaussian surface heat source model and peak linear attenuation Gaussian cylinder heat source. The welding current mainly affects the penetration of the weld, followed by the extension of the wire, and lastly the welding speed. Increasing the welding current can transition droplet transfer from globular to spray, as well as alter microstructure development and mechanical characteristics. Suggested parameters for penetrating the 5 mm root were put forward. The BPNN-GA model established can effectively predict weld formation, and points out the optimal welding parameters.
Reference distributions of aortic calcification and association with Framingham risk score
Authors: Horbal Steven R. , Derstine Brian A. , Brown Edward , Su Grace L. , Wang Stewart C. , Holcombe Sven A.
Published: June 2023

Evidence supporting aortic calcification as a leverageable cardiovascular risk factor is rapidly growing. Given aortic calcification’s potential as a clinical correlate, we assessed granular vertebral-indexed calcification measurements of the abdominal aorta in a well curated reference population. We evaluated the relationship of aortic calcification measurements with Framingham risk scores. After exclusion, 4073 participants from the Reference Analytic Morphomic Population with varying vertebral levels were included. The percent of the aortic wall calcified was used to assess calcification burden at the L1–L4 levels. Descriptive statistics of participants, sex-specific vertebral indexed calcification measurements, relational plots, and relevant associations are reported. Mean aortic attenuation was higher in female than male participants. Overall, mean aortic calcium was higher with reference to inferior abdominal aortic measurements and demonstrated significant differences across all abdominal levels [L3 Area (mm$$^2$$

2

): Females 6.34 (sd 16.60), Males 6.23 (sd 17.21); L3 Volume (mm$$^3$$

3

): Females 178.90 (sd 474.19), Males 195.80 (sd 547.36); Wall Calcification (%): Females (L4) 6.97 (sd 16.03), Males (L3) 5.46 (13.80)]. Participants with elevated calcification had significantly higher Framingham risk scores compared to participants with normal calcification scores. Opportunistically measuring aortic calcification may inform further cardiovascular risk assessment and enhance cardiovascular event surveillance efforts.
Optimal timing for antimicrobial prophylaxis to reduce surgical site infections: a retrospective analysis of 531 patients
Authors: Paasch Christoph , Schildberg Claus , Lünse Sebastian , Heisler Sophie , Meyer Jens , Kirbach Jette , Kobelt Elisa , Hunger Richard , Haller Isabel-Elena , Helmke Chrissanthi , Mantke Rene
Published: June 2023

It has been revealed that the administration of an antimicrobial prophylaxis (AP) reduces the rate of surgical site (SSI) following colorectal cancer surgery. Nevertheless, the optimal timing of this medication remains unclear. The aim of this study was to determine more precisely the optimal time for administering antibiotics and to see if this could reduce the number of possible surgical site infections. The files of individuals who underwent colorectal cancer surgery at the University Hospital Brandenburg an der Havel (Germany) between 2009 and 2017 were analyzed. Piperacillin/tazobactam, cefuroxime/metronidazole and mezlocillin/sulbactam were administered as AP regimens. Timing of AP was obtained. The primary objective was the rate of SSIs based on CDC criteria. Multivariate analysis took place to identify risk factors for SSIs. A total of 326 patients (61.4%) received an AP within 30 min, 166 (31.3%) between 30 and 60 min, 22 (4.1%) more than 1 h before surgery, and 15 (2.8%) after surgery. In 19 cases (3.6%) a SSI occurred during hospital stay. A multivariate analysis did not identify AP timing as a risk factor for the occurrence of SSIs. With significance, more surgical site occurrences (SSO) were diagnosed when cefuroxime/metronidazole was given. Our results suggest that AP with cefuroxime/metronidazole is less effective in reducing SSO compared with mezlocillin/sulbactam and tazobactam/piperacillin. We assume that the timing of this AP regimen of < 30 min or 30–60 min prior to colorectal surgery does not impact the SSI rate.
Predictive value of PET metabolic parameters for occult lymph node metastases in PET/CT defined node-negative patients with advanced epithelial ovarian cancer
Authors: Xue Bing , Wang Xihai
Published: June 2023

Accurate lymph node metastasis (LNM) prediction is crucial for patients with advanced epithelial ovarian cancer (AEOC) since it guides the decisions about lymphadenectomy. Previous studies have shown that occult lymph node metastasis (OLNM) is common in AEOC. The objective of our study is to quantitatively assess the probability of occult lymph node metastasis defined by 18F-Fluorodeoxyglucose PET/CT in AEOC and explore relationship between OLNM and PET metabolic parameters. The patients with pathologically confirmed AEOC who underwent PET/CT for preoperative staging at our institute were reviewed. Univariate and multivariate analysis were performed to evaluate the predictive value of PET/CT-related metabolic parameters for OLNM. The result of our study showed metastatic TLG index had a better diagnostic performance than other PET/CT-related metabolic parameters. Two variables were independently and significantly associated with OLNM in multivariate analysis: metastatic TLG index and primary tumor location. The logistic model combining metastatic TLG index, primary tumor location, and CA125 might be a promising tool to effectively predict the individualized possibility of OLNM for AEOC patients.
Improved on-treatment fibrosis-4 during antiviral therapy and lower hepatocellular carcinoma risk in cirrhotic patients with hepatitis B
Authors: Oh Joo Hyun , Park Yewan , Goh Myung Ji , Sinn Dong Hyun , Ahn Sang Bong , Kang Wonseok , Gwak Geum-Youn , Paik Yong-Han , Choi Moon Seok , Lee Joon Hyeok , Paik Seung Woon
Published: June 2023

Normalization of serum alanine aminotransferase (ALT) levels is one of the goals of hepatitis B treatment. However, ALT levels in cirrhosis patients might be normal or mildly elevated regardless of ongoing inflammation. Therefore, we examined whether on-treatment ALT and other potential on-treatment indicators could be clinical surrogates of antiviral therapy in HBV-related cirrhosis. A total of 911 patients with HBV-related liver cirrhosis who started treatment with entecavir or tenofovir were analyzed. At 1 year of antiviral therapy, we evaluated ‘ALT normalization’, ‘undetectable serum HBV DNA’, ‘fibrosis-4 (FIB-4) index improvement’, and ‘serum HBeAg loss’ as potential biomarkers for HCC development. During 6.6 (3.8–10.2) years of follow-up, 222 patients (24.3%) newly developed HCC. Undetectable HBV DNA levels at 1 year were observed in 667 patients (73.2%), and the HCC incidence was significantly lower in this population (adjusted hazard ratio (HR) 0.66, 95% CI 0.50–0.87). Improvement of the FIB-4 index (< 3.25) was associated with a lower risk of HCC in 478 patients with an elevated FIB-4 index (adjusted HR 0.59, 95% CI 0.55–0.82). However, there was no significant difference in HCC risk between those with and without normalization of ALT levels (p = 0.39) among those with elevated ALT levels or between those with and without HBeAg seroconversion (p = 0.55) among HBeAg-positive patients. Therefore, on-treatment FIB-4 levels at 1 year are clinically useful surrogates of antiviral therapy for HBV-related cirrhosis patients.
Evaluation of the mechanical stability of intraocular lenses using digital image correlation
Authors: Cabeza-Gil Iulen , Frechilla Javier , Calvo Begoña
Published: June 2023

This study aimed to evaluate the mechanical stability of seven different intraocular lens (IOL) haptic designs by using digital image correlation to measure their mechanical biomarkers (axial displacement, tilt, and rotation) under quasi-static compression. The IOLs were compressed between two clamps from 11.00 up to 9.50 mm whilst a 3D deformation dataset was acquired every 0.04 mm. Results revealed that flexible and mixed IOL designs exhibited better mechanical response for smaller compression diameters compared to stiff designs. Conversely, stiff designs performed better for larger compression diameters. These findings may aid in the selection and development of more mechanically stable IOL designs.
Hydrogenic spin-valley states of the bromine donor in 2H-MoTe2
Authors: Sheina Valeria , Lang Guillaume , Stolyarov Vasily , Marchenkov Vyacheslav , Naumov Sergey , Perevalova Alexandra , Girard Jean-Christophe , Rodary Guillemin , David Christophe , Sop Leonnel Romuald , Pierucci Debora , Ouerghi Abdelkarim , Cantin Jean-Louis , Leridon Brigitte , Ghorbani-Asl Mahdi , Krasheninnikov Arkady V. , Aubin Hervé
Published: June 2023

In semiconductors, the identification of doping atomic elements allowing to encode a qubit within spin states is of intense interest for quantum technologies. In transition metal dichalcogenides semiconductors, the strong spin-orbit coupling produces locked spin-valley states with expected long coherence time. Here we study the substitutional Bromine BrTe dopant in 2H-MoTe2. Electron spin resonance measurements show that this dopant carries a spin with long-lived nanoseconds coherence time. Using scanning tunneling spectroscopy, we find that the hydrogenic wavefunctions associated with the dopant levels have characteristics spatial modulations that result from their hybridization to the Q-valleys of the conduction band. From a Fourier analysis of the conductance maps, we find that the amplitude and phase of the Fourier components change with energy according to the different irreducible representations of the impurity-site point-group symmetry. These results demonstrate that a dopant can inherit the locked spin-valley properties of the semiconductor and so exhibit long spin-coherence time.
Kramers nodal lines and Weyl fermions in SmAlSi
Authors: Zhang Yichen , Gao Yuxiang , Gao Xue-Jian , Lei Shiming , Ni Zhuoliang , Oh Ji Seop , Huang Jianwei , Yue Ziqin , Zonno Marta , Gorovikov Sergey , Hashimoto Makoto , Lu Donghui , Denlinger Jonathan D. , Birgeneau Robert J. , Kono Junichiro , Wu Liang , Law Kam Tuen , Morosan Emilia , Yi Ming
Published: June 2023

Kramers nodal lines (KNLs) have recently been proposed theoretically as a special type of Weyl line degeneracy connecting time-reversal invariant momenta. KNLs are robust to spin orbit coupling and are inherent to all non-centrosymmetric achiral crystal structures, leading to unusual spin, magneto-electric, and optical properties. However, their existence in in real quantum materials has not been experimentally established. Here we gather the experimental evidence pointing at the presence of KNLs in SmAlSi, a non-centrosymmetric metal that develops incommensurate spin density wave order at low temperature. Using angle-resolved photoemission spectroscopy, density functional theory calculations, and magneto-transport methods, we provide evidence suggesting the presence of KNLs, together with observing Weyl fermions under the broken inversion symmetry in the paramagnetic phase of SmAlSi. We discuss the nesting possibilities regarding the emergent magnetic orders in SmAlSi. Our results provide a solid basis of experimental observations for exploring correlated topology in SmAlSi
Expanding climate policy adoption improves national mitigation efforts
Authors: Nascimento Leonardo , Höhne Niklas
Published: June 2023

To identify means to improve mitigation efforts, we investigated whether the number of climate policies is associated with emission projections up to 2030 and compared policies’ prevalence across country groups. We find that larger and more comprehensive policy portfolios are conducive to emission reductions, regardless of whether absolute emissions increase or already decline. However, country groups have distinct entry points to expand climate policy. Countries with fast-increasing emissions have significantly fewer policies overall but policies are especially missing in energy-demand sectors, such as buildings and transport. Countries with stalling emissions lack climate strategies and other cross-sectoral policies. This suggests the need for better coordination of mitigation efforts across sectors. In all country groups that fail to reduce emissions, policies to reduce energy and material demand are also substantially fewer. Despite the collective increase of policies in force, countries can still expand climate policy to use the full breadth of mitigation options available.
Anti-diabetic Activity of Antioxidative Teas and Tea Polyphenol Supplements
Authors: Han Zisheng , Zhang Liang , Wan Xiaochun , Ho Chi-Tang
Published: June 2023

Diabetes, especially type 2 diabetes (T2D) mellitus, has become one of the typical chronic diseases around the world. As the most consumed beverage, tea and its main compounds, that is, tea polyphenols, have shown various regulation effects on diabetes progression. The benefits of tea and tea polyphenols on diabetes have been verified by enzyme models, cell bioassays, and animal experiments. The mechanism may be attributed to glucose hydrolysis, glucose transport, glycogen synthesis, energy expenditure, immunity regulation, and anti-inflammatory and antioxidant capacity, among others. Furthermore, population-based investigations have mostly confirmed the effects of tea on reducing diabetes risk in many epidemiological studies. However, the intervention results of tea and tea polyphenols are not consistent. The main antioxidant mechanisms of tea and tea polyphenols may involve improvement of antioxidant enzymes, inhibition of lipid peroxidation, scavenging of free radicals, and complexation of metal ions. Tea and its bioactive components offer prevention and treatment of T2D through several mechanisms, including protecting pancreatic β-cells, improving insulin resistance, inhibiting the digestion, absorption and metabolism of carbohydrates as well as regulating the gut microbiota. In addition, they also benefit diabetic complications, such as diabetic nephropathy and diabetic cardiopathy. This chapter discusses the evidence associated with the anti-diabetic activities of tea and its reactive components, as well as the underlying mechanisms that have been studied by researchers over recent years.
Access to and reactions of P-functional 1,4-dihydro-1,4-diphosphinines fused to two TTF units
Authors: Kermanshahian Shahriar , Kalisch Tim , Kelemen Zsolt , Schnakenburg Gregor , Nyulászi László , Boeré René T. , Streubel Rainer
Published: June 2023

Synthesis of redox active 1,4-dihydro-1,4-diphosphinines and new reactions, including conversion of aP-chloro derivative into the corresponding 1,4-diphosphabarrelene are presented. The products have been confirmed and studied by cyclic voltammetry.
Interface engineering of the NiO/CeO2@NF heterostructure to boost the electro-oxidation of 5-hydroxymethylfurfural
Authors: He Xiu , Mo ZhenZhen , Liu Huiling , Wang Cheng
Published: June 2023

The interface engineering of NiO/CeO2@NF can regulate the electronic properties of Ce and Ni atoms, regulate intermediate adsorption, and promote electron/charge transfer, greatly contributing to high HMFOR performance.
Molecularly or atomically precise nanostructures for bio-applications: how far have we come?
Authors: Wang Jie , Li Ping , Wang Chao , Liu Ning , Xing Dongming
Published: June 2023

A huge variety of nanostructures are promising for biomedical applications, but only a few have been practically applied.
Therapeutic potential of 1,3,4-oxadiazoles as potential lead compounds for the treatment of Alzheimer's disease
Authors: Naseem Saira , Temirak Ahmed , Imran Aqeel , Jalil Saquib , Fatima Shamool , Taslimi Parham , Iqbal Jamshed , Tasleem Mussarat , Tahir Muhammad Nawaz , Shafiq Zahid
Published: June 2023

Monoamine oxidase and cholinesterase enzymes are important targets for the treatment of several neurological diseases especially depression, Parkinson disease and Alzheimer's.
On the effect of gender on secondary school students’ causal attributions to choose or abandon physics & chemistry
Authors: Ardura Diego , Zamora Ángela , Pérez-Bitrián Alberto
Published: June 2023

Secondary school students’ early choices related to staying in the science track define their future decisions to choose chemistry at college. This investigation aims at analyzing the role of gender in students’ causal attributions to choose or abandon chemistry when it first becomes optional in the Spanish educational system. Our analyses uncovered a relevant effect of gender in the students’ decision, boys being more likely to choose physics & chemistry when they face, for the first time, the possibility of continuing or opting out the subject. Besides, students’ causal attributions to the subject relationship with mathematics and to friends are affected by gender regardless of the students’ level of motivation. In turn, there is a gender effect in attributions to friends and media only in the case of highly-motivated students. A multinomial logistic regression model revealed that gender is a strong predictor of the students’ decision. The regression model also uncovered a significant interaction effect between gender and attributions to the subject relationship with mathematics, girls becoming less likely to choose physics & chemistry when the latter increase. Our results highlight the need of working on the students’ and families’ stereotypes and propose gender-balanced teaching models to close the gap between girls’ and boys' attitudes, motivation, and anxiety towards mathematics in the context of physics & chemistry teaching and learning.
3D printing of self-supported solid electrolytes made of glass-derived Li1.5Al0.5Ge1.5P3O12 for all-solid-state lithium-metal batteries
Authors: Sabato A. G. , Nuñez Eroles M. , Anelli S. , Sierra C. D. , Gonzalez-Rosillo J. C. , Torrell M. , Pesce A. , Accardo G. , Casas-Cabanas M. , López-Aranguren P. , Morata A. , Tarancón A.
Published: June 2023

LAGP solid electrolyte was successfully 3D printed by stereolithography, producing a corrugated shape, which reduced the area specific resistance and improved the durability during cycling.
Universal passive radiative cooling behavior of aerogels
Authors: Ma Bingjie , Wu Bing , Hu Peiying , Liu Ling , Wang Jin
Published: June 2023

The universal passive radiative cooling behavior of aerogels is revealed and their impact on thermal conductivity-related thermal insulation performance is investigated.
Survey method for field measurement of rubber ball impact sound in reinforced concrete apartment houses in Korea – Based on the Korean measurement method
Authors: Jeong Jeongho , Ryu Jongkwan
Published: June 2023

The rubber ball impact sound has been standardized by ISO 10140 series and ISO 16283-2 for laboratory and field measurements, respectively. The ISO 10052 standard specifies a survey method for the impact sound measurement using a tapping machine and a rubber ball. This study proposed measurement position for the survey method which is highly correlated with result based on the Korean Standards (KS) and the building regulation of South Korea for engineering method. The rubber ball impact sounds were measured in 79 reinforced concrete apartment houses, which have a centre point and four perimeter points for both exciting and receiving sounds. The proposed survey method was validated for only a specific type of apartment building layout and construction in the South Korean environment. The excitation and receiving points in the perimeter having the most similar characteristics to the results obtained using the Korean engineering methods were first selected. By combining the selected perimeter point and centre point for both the excitation and receiving sounds, the characteristics of each combination were compared with the results obtained using the Korean engineering method. When one excitation point or receiving point in the perimeter was added to the centre point for the proposed survey method, the difference between the measurement result using the engineering and proposed survey method decreased. The standard deviation of the difference between the SNQs of the proposed survey method and the Korean engineering method for measuring the rubber ball impact sound was smaller than 2 dB.
Rates of convergence in periodic homogenization of nonlocal Hamilton–Jacobi–Bellman equations,
Authors: Rodríguez-Paredes Andrei , Topp Erwin
Published: June 2023

In this paper we provide a rate of convergence for periodic homogenization of Hamilton–Jacobi–Bellman equations with nonlocal diffusion. The result is based on the regularity of the associated effective problem, where convexity plays a crucial role. The necessary regularity estimates are made possible by a representation formula we obtain for the effective Hamiltonian, a result that has an independent interest.
Payment policy for a three-echelon supply chain management under advertisement-driven demand
Authors: Mondal Ashish Kumar , Pareek Sarla , Sarkar Biswajit
Published: June 2023

Payment and selling are two important policies for a supply chain management. All participating supply chain players can earn profit based on the successful implementation of these two policies. The payment policy provides buyers some extra time to pay for the product. This research introduces a single-supplier, a single-manufacturer, and multi-retailer-based three-echelon supply chain management under advertising and payment policies. Product delivery among supply chain players is made with the help of a transportation policy. The transportation policy is environment-friendly and helps retailers with their cost management. It is demonstrated that advertising positively influences sales through an advertisement-driven market demand for the product. The model aims to reduce supply chain cost and maximizes profit by considering a single-setup multiple-delivery policy, variable transportation cost, variable carbon emissions costs, and trade-credit policy. The objective function is optimized for cases: Case 1 and Case 2, based on the payment period. A classical optimization method is employed to obtain the solution of the model. A numerical example, sensitivity analysis, and graphical representations are given to illustrate the model. Results show that Case 2, where cycle time is greater than the payment period, is 45.36% more profitable than Case 1.
Rauchen in Netflix-Spielfilmen und Jugendschutz
Authors: Hanewinkel Reiner , Neumann Clemens , Morgenstern Matthis
Published: June 2023

Hintergrund Mit dem Ziel des Jugendschutzes fordert die Weltgesundheitsorganisation, Filme mit Rauchszenen als ungeeignet für Jugendliche einzustufen. Der Konsum von Filmen erfolgt in den letzten Jahren – noch einmal verstärkt durch die COVID-19-Pandemie – zunehmend über Videostreamingdienste, was den Jugendschutz vor neue Herausforderungen stellt.

Fragestellung Die Häufigkeit des Rauchens in Netflix-Spielfilmen sollte erhoben und die Altersempfehlungen für Netflix-Produktionen mit Rauchszenen untersucht werden.

Methode Insgesamt 235 Filme, die in den Jahren 2021 und 2022 exklusiv zum Streaming von der Plattform Netflix bereitgestellt wurden, wurden inhaltsanalysiert. Es wurde betrachtet, (1) wie hoch der Anteil an rauchfreien Filmen in dieser Filmstichprobe war, (2) wie häufig Rauchszenen in diesen Filmen auftraten und (3) wie hoch der Anteil der Filme mit Rauchszenen war, die in Deutschland sowie den USA als für Jugendliche geeignet eingestuft wurden. Als für Kinder und Jugendliche geeignet wurden alle Filme angesehen, deren Altersfreigabe unter 16 Jahren lag.

Ergebnisse In 113 von 235 analysierten Filmen wurde geraucht (48,1%). Von den 113 Filmen mit Rauchszenen wurden in Deutschland 57 (50,4%) und in den USA 26 Filme (23,0%) als jugendfrei eingestuft (p<0,001). 3310 Rauchszenen wurden insgesamt registriert. Davon waren in Deutschland 39,4% (N=1303) in Filmen mit Jugendfreigabe zu sehen, bei Netflix-USA lag dieser Anteil bei 15,8% (N=524).

Diskussion Rauchen tritt in Netflix-Filmen häufig auf. Weder in den USA noch in Deutschland hält sich Netflix an die Empfehlungen des WHO-Rahmenübereinkommens zur Eindämmung des Tabakkonsums, den Zugang von Jugendlichen zu Filmen, in denen das Rauchen dargestellt wird, zuverlässig zu beschränken. Allerdings gelingt der Jugendschutz in den USA im Vergleich zu Deutschland besser, da die Hälfte der Netflix-Filme mit Rauchszenen in Deutschland als jugendgeeignet eingestuft wurden, in den USA weniger als ein Viertel.
Synergistic treatment of genetic kidney disease with DNA methylation inhibitors
Authors: Patrick Chris
Published: June 2023

A combination of drugs reduces the growth of cysts related to autosomal dominant polycystic kidney disease.
A general objective-orientated automatic optimization of multi-layer thermochromic smart glazes
Authors: Liu Baoshun , Zhao Xiujian
Published: June 2023

VO2-based thermochromic smart glazes have attracted much attention for energy-saving buildings. Their practical applications need high visible luminous transmittance (Tlum) and high solar light modulation efficiency (ΔTsol). High Tlum and ΔTsol are difficult to be realized by a single-layer VO2 film, and constructing multi-layer film assemblies has been a widely adopted way to increase Tlum and ΔTsol. Tlum and ΔTsol of a multi-layer film assembly are multi-dimensional functions of the complex dielectric permittivity and the thickness of each layer, respectively. The current research reported a computer automatic searching of the total minimum of an evaluation function that together takes the cool-state Tlum, hot-state Tlum, and ΔTsol into account. It can be used to optimize a multi-layer assembly composed of any components according to the given objectives and weights for Tlum and ΔTsol. Different multi-layer film systems consisting of SiO2, TiO2, and VO2 layers were optimized. The best film system was proposed to be TiO2/VO2/TiO2/s, and the effects of objectives and weights on Tlum and ΔTsol were also checked. The physical reason that leads to high Tlum and ΔTsol was analyzed based on the optimized reflectance and transmittance spectra. The RGB tristimulus of the optimized multi-layer system can also be obtained from the transmittance spectra. The program can also realize an automatic optimization with some variables being constrained, and the composite layers are also involved under the basis of the Bruggeman effective media theory. The results showed that a satisfied objective-orientated optimization can be realized for a thermochromic layer system; this should be meaningful for the design and preparation of the multi-layer film assemblies according to the different user's demands.
On equilibrium states of fluid membranes
Authors: Olshanskii Maxim A.
Published: June 2023

The paper studies the equilibrium configurations of inextensible elastic membranes exhibiting lateral fluidity. Using a continuum description of the membrane's motions based on the surface Navier–Stokes equations with bending forces, the paper derives differential equations governing the mechanical equilibrium. The equilibrium conditions are found to be independent of lateral viscosity and relate tension, pressure, and tangential velocity of the fluid. These conditions suggest that either the lateral fluid motion ceases or non-decaying stationary flow of mass can only be supported by surfaces with Killing vector fields, such as axisymmetric shapes. A shape equation is derived that extends the classical Helfrich model with an area constraint to membranes of non-negligible mass. Furthermore, the paper suggests a simple numerical method to compute solutions of the shape equation. Numerical experiments conducted reveal a diverse family of equilibrium configurations. The stability of equilibrium states involving lateral flow of mass remains an unresolved question.
Wall-modeled large-eddy simulation integrated with synthetic turbulence generator for multiple-relaxation-time lattice Boltzmann method
Authors: Davidson Lars
Published: June 2023

The synthetic turbulence generator (STG) lies at the interface of the Reynolds averaged Navier–Stokes (RANS) simulation and large-eddy simulation (LES). This paper presents an STG for the multiple-relaxation-time lattice Boltzmann method (LBM) framework at high friction Reynolds numbers, with consideration of near-wall modeling. The Reichardt wall law, in combination with a force-based method, is used to model the near-wall field. The STG wall-modeled LES results are compared with turbulent channel flow simulations at Reτ=1000,2000,5200 at different resolutions. The results demonstrate good agreement with direct numerical simulation, with the adaptation length of 6–8 boundary layer thickness. This method has a wide range of potentials for hybrid RANS/LES-LBM related applications at high friction Reynolds numbers.
Aerodynamic noise reduction of a blunt flat plate by trailing-edge blowing
Authors: Maryami Reza
Published: June 2023

This study investigates the influence of air blowing on the aerodynamic noise generated by a flat plate with a blunt trailing edge. The uniform blowing was applied through evenly spaced holes along the span at the base of the flat plate. Acoustic pressure measurements were conducted in an anechoic wind tunnel using a free-field microphone at Reynolds numbers ranging from 2.8×105 to 6.5×105. Particle image velocimetry measurements were performed to obtain time-resolved evolution and statistics of the flow velocity field, providing a detailed understanding of the noise reduction mechanisms. The results demonstrated that air blowing effectively reduces both the amplitude and bandwidth of tonal and broadband noise within a limited frequency range. This phenomenon was attributed to the stabilization of separated shear layers over a longer distance by air blowing and a decrease in turbulent kinetic energy in the near-wake region. It was shown that air blowing suppresses the tonal peak of vertical velocity fluctuations and narrows the wake width, which accounts for the increase of vortex shedding frequency and a potential drag reduction. Generally, the effects of air blowing on vortex shedding at the blunt trailing edge are analogous to those of a splitter plate. The unaffected convective velocity of the large-scale vortex structures and the enhanced spanwise coherence in the vortex formation region provide further evidence to this analogy.
Thin films in hydrodynamic lubrication regime: The Osiris friction setup
Authors: Barazzutti Cedric , Cayer-Barrioz Juliette , Mazuyer Denis
Published: June 2023

A model hydrodynamic lubrication tribometer consisting of two hydrodynamic journal bearings working under thin film conditions was developed to investigate the mechanisms of hydrodynamic friction with low-viscosity fluids and the role of surface effects. A small nominal radial clearance of about 5 µm was considered between the two surfaces. This fully instrumented setup provides in situ information on the sheared fluid film in terms of simultaneous measurements of film thickness; localization and extension of the cavitation zone, with a resolution of 30°; nominal friction torques up to 0.5 N m, with an accuracy of 0.05 mN m; temperature; and the position of the shaft for velocities up to 12 000 rpm. To illustrate the capability of the Osiris tribometer, thin hydrodynamic film measurements were performed on smooth surfaces. The results are presented here, and the thermal effects, acceleration, and inertia contributions are discussed. Finally, the influence of the surface topography using textured surfaces was demonstrated and the role of adsorbed layers on the surface due to fluid formulation was highlighted.
Dynamic and thermodynamic stability of charged perfect fluid stars
Authors: Shi Kai , Tian Yu , Wu Xiaoning , Zhang Hongbao , Zhang Jingchao
Published: June 2023

We perform a thorough analysis of the dynamic and thermodynamic stability for the charged perfect fluid star by applying the Wald formalism to the Lagrangian formulation of Einstein–Maxwell-charged fluid system. As a result, we find that neither the presence of the additional electromagnetic field nor the Lorentz force experienced by the charged fluid makes any obstruction to the key steps towards the previous results obtained for the neutral perfect fluid star. Therefore, the criterion for the dynamic stability of our charged star in dynamic equilibrium within the symplectic complement of the trivial perturbations with the Arnowitt-Deser-Misner (ADM) 3-momentum unchanged is given by the non-negativity of the canonical energy associated with the timelike Killing field, where it is further shown for both non-axisymmetric and axisymmetric perturbations that the dynamic stability against these restricted perturbations also implies the dynamic stability against more generic perturbations. On the other hand, the necessary condition for the thermodynamic stability of our charged star in thermodynamic equilibrium is given by the positivity of the canonical energy of all the linear on-shell perturbations with the ADM angular momentum unchanged in the comoving frame, which is equivalent to the positivity of the canonical energy associated with the timelike Killing field when restricted onto the axisymmetric perturbations. As a by-product, we further establish the equivalence of the dynamic and thermodynamic stability with respect to the spherically symmetric perturbations of the static, spherically symmetric isentropic charged star.
Quasiclassical model of inhomogeneous cosmology
Authors: Bojowald Martin , Hancock Freddy
Published: June 2023

Fluctuation terms and higher moments of a quantum state imply corrections to the classical equations of motion that may have implications in early-Universe cosmology, for instance in the state-dependent form of effective potentials. In addition, space-time properties are relevant in cosmology, in particular when combined with quantum corrections required to maintain general covariance in a consistent way. Here, an extension of previous investigations of static quasiclassical space-time models to dynamical ones is presented, describing the evolution of one-dimensional space as in the classical Lemaitre–Tolman–Bondi models. The corresponding spatial metric has two independent components, both of which are in general subject to quantum fluctuations. The main result is that individual moments from both components are indeed required for general covariance to be maintained at a semiclassical level, while quantum correlations between the components are less relevant.
Optimal readout scheme for multi-degree-of-freedom seismometers
Authors: Peng Xingrui , Martynov Denis , Zhu Zonghong , Miao Haixing
Published: June 2023

The low-frequency performance of advanced gravitational-wave detectors is limited by the seismic noise and the associated control noise. A six-degree-of-freedom seismometer has been proposed in (Mow-Lowry and Martynov 2019 Class. Quantum Grav.
36 245006) to improve the active isolation system. The standard readout scheme, which directly inverts the sensing matrix, gives dynamically independent but not statistically independent estimators for different degrees of freedom. This paper studies the optimal readout scheme by using optimal filters to combine the sensor outputs. The improvement is ultimately limited by the sensor noise and the ground motion, which decreases the correlation. For the real-time implementation, we have considered fitting the optimal filters numerically under the passive and causal constraint.
Pitfalls in applying gravitomagnetism to galactic rotation curve modelling
Authors: Glampedakis Kostas , Jones David Ian
Published: June 2023

The flatness of galaxy rotation curves at large radii is generally considered to be a significant piece of evidence in support of the existence of dark matter. Several studies have claimed that post-Newtonian corrections to the Newtonian equations of galaxy dynamics may remove (at least to some degree) the need for dark matter. A few recent studies have examined these claims, and identified errors in their reasoning. We add to this critique by giving what we consider to be particularly simple and transparent description of the errors made in these post-Newtonian calculations, some of which were of a rather technical nature, others more fundamental, e.g. the loss of the correct relativistic scaling, promoting small corrections to order unity changes. Our work reinforces the orthodoxy that post-Newtonian effects are indeed too small to significantly alter galactic rotation curves, and will hopefully serve as a useful guide for others, pointing out subtle errors that one might inadvertently make in such calculations.
State estimation approach to dual-modal imaging of two-phase flow based on electromagnetic flow tomography and electrical tomography
Authors: Arif M Ziaul , Seppänen Aku , Vauhkonen Marko
Published: June 2023

Monitoring, control and design of industrial processes involving multiphase flows often call for analysis of data from multiple sensors which give information on different quantities of the flowing materials. An example of such case is the problem of monitoring the flow of oil–water mixture: the phase fractions of oil and water, their velocities and volumetric flow rates cannot be retrieved from measurements given by a single sensing/imaging modality. For this reason, multi-modal tomographic imaging systems have been developed. In multi-phase flows, the quantities retrieved from different tomographic instruments are often interconnected—for example, the evolutions of the phase fractions depend on their velocities and vice versa. However, the analysis of data from different tomographic modalities is usually done separately—without taking into account physics that link the quantities of interest. In this paper, we propose a novel approach to image reconstruction in dual-modal tomography of multiphase flows. The governing idea is to combine the two modalities via Bayesian state estimation, that is, we write models that approximate connections between different quantities involved in the process and use sequential measurements from both modalities to jointly estimate these temporally evolving quantities. As an example case, we consider a dual-modal system comprising the electromagnetic flow tomography (EMFT) and electrical tomography (ET). While the EMFT is sensitive to the velocity field but also depends on the phase fractions of fluids, ET measurements are directly linked to phase fractions only. We study the performance of state estimation in EMFT-ET tomography with a set of numerical simulations. The results demonstrate that it outperforms the conventional stationary reconstruction approach, and also provides means for uncertainty quantification in multiphase flow imaging.
Numerical approaches in simulating Trichel pulse characteristics in point-plane configuration
Authors: Shaygani Afshin , Adamiak Kazimierz
Published: June 2023

In this work, a detailed comparison is made of a few different approaches to numerical modeling of non-equilibrium gas discharge plasmas in dry ambient air at atmospheric conditions, leading to Trichel pulse discharge. Simulation models are based on a two-dimensional axisymmetric finite element discretization of point-plane geometry. The negative corona discharge and the hydrodynamic approximation for generic ionic species (electrons, positive and negative ions) are used. The models account for the drift, diffusion, and reactions of the species. They comprise continuity equations coupled to Poisson’s equation for the electric field. Three different formulations were used to specify the ionic reaction rate coefficients. In the first one, the reaction coefficients are approximated by the analytical expressions as a function of the electric field intensity. Two others extract the reaction coefficients from the solution of the Boltzmann equation as a function of the reduced electric field or the electron energy. The effect of gas flow and heating on the pulse characteristics is also investigated. The accuracy of the models has been validated by comparing them with the experimental data.
Controllable spin splitting in 2D ferroelectric few-layer γ-GeSe
Authors: Shi Shuyi , Hao Kuan-Rong , Ma Xing-Yu , Yan Qing-Bo , Su Gang
Published: June 2023

γ-GeSe is a new type of layered bulk material that was recently successfully synthesized. By means of density functional theory first-principles calculations, we systematically studied the physical properties of two-dimensional (2D) few-layer γ-GeSe. It is found that few-layer γ-GeSe are semiconductors with band gaps decreasing with increasing layer number; and 2D γ-GeSe with layer number n ⩾ 2 are ferroelectric with rather low transition barriers, consistent with the sliding ferroelectric mechanism. Particularly, spin–orbit coupling induced spin splitting is observed at the top of valence band, which can be switched by the ferroelectric reversal; furthermore, their negative piezoelectricity also enables the regulation of spin splitting by strain. Finally, excellent optical absorption was also revealed. These intriguing properties make 2D few-layer γ-GeSe promising in spintronic and optoelectric applications.
Kissing the cheeks of Huygens
Authors: Schut Marthe , Schut Paul , Heck André
Published: June 2023

How well do the so-called cheeks of Huygens enforce a constant time of oscillation on a pendulum, independent of the amplitude of the pendulum swing? We use a video measurement tool to test it with a homemade experimental setup that can be fruitfully used in classroom and physics laboratory settings. Data fits reveal how well the setup confirms the usefulness of the cheeks of Huygens. Comparisons of computer model results with recorded data have been made for the same purpose. The equation of motion of a pendulum with a string of arbitrary length that winds along two surfaces of cycloidal cheeks is derived, too. Numerical solutions of this equation are used for the error analysis of measurements with the homemade setup.
Ammonia generation in Ns pulse and Ns pulse/RF discharges over a catalytic surface
Authors: Yang Xin , Richards Caleb , Adamovich Igor V
Published: June 2023

Plasma-catalytic ammonia synthesis in a ns pulse discharge and a ‘hybrid’ ns pulse/RF discharge in plane-to-plane geometry is studied by Fourier Transform infrared absorption spectroscopy. The data are taken in a preheated H2–N2 mixture, with and without Ni/γ-Al2O3 or Co/γ-Al2O3 catalyst placed in the discharge section. The measurement results are taken using two different approaches. The first is a ‘single-stage’ process, where a ns pulse discharge in the H2–N2 mixture is sustained continuously. In this case, the ammonia yield increases slowly, over a period of tens of minutes. The second is a ‘two-stage’ process, where the catalyst is first activated by the ns pulse discharge sustained in pure nitrogen, and then the activated catalyst is exposed to the H2–N2 flow, with or without the discharge. In this case, a strong overshoot of the NH3 number density at the reactor exit is detected, by over a factor of two compared to the single-stage process. After the initial overshoot, the ammonia yield gradually decreases to the ‘single stage’ value (with the discharge on), or to near zero (with the discharge off). The results demonstrate that the ammonia yield in the plasma-catalytic reactor is controlled by the N atom accumulation on the catalyst surface, which reacts with H atoms thermally dissociated on the catalyst or generated in the plasma. The results also show that the plasma-catalytic ammonia yield is significantly higher compared to that in the ns pulse discharge without the catalyst. The accumulation of H atoms on the catalyst, with their subsequent reactions with N atoms generated in the plasma, is of relatively minor importance at the present conditions. An additional series of measurements was made with a sub-breakdown RF waveform overlapped with the ns pulse discharge train, to enhance the vibrational excitation of nitrogen. The ammonia yield measured with the RF waveform added is approximately 20% higher compared to that at the baseline ns pulse discharge conditions, both with and without the catalyst. This effect is weaker compared to that of the catalyst activation by N atoms. Additional data are necessary to isolate the possible effect of the vibrationally excited N2 molecules on the ammonia synthesis in the plasma catalytic reactions.
Multiaxial shape memory effect of thermo-induced shape memory polyurethane under proportional tension-torsion loading
Authors: Liang Zhihong , Li Jian , Chen Kaijuan , Dong Yu , Yu Chao , Kan Qianhua
Published: June 2023

Shape memory behavior of thermo-induced shape memory polyurethane (TSMPU) under proportionally multiaxial loading is investigated experimentally. The shape memory effect is discussed under different axial and torsional loading angles. By comparing the equivalent stress-equivalent strain curves under different loading angles, it is found that the difference in thermo-mechanical behavior is mainly reflected in the shape memory effect. The equivalent characteristic quantities describing the shape memory effect are extracted from the experimental results. By analyzing their evolutions in the strain and stress spaces, it is found that the shape memory effect shows obvious anisotropy under different loading angles, i.e. the equivalent recovery rate of TSMPU increases with the increase of the loading angles. These results are helpful to establish a thermo-mechanical constitutive model for describing the shape memory effect under multiaxial loading.