bluuebunny/crossref_metadata_2025 huggingface dataset:
Modelling of blast furnace ironmaking process based on digital twin
Authors: Xu Yonghong , Yang Chunjie , Liu Zhe
Published: October 2024

The blast furnace ironmaking process is a crucial step in the steel industry. Effectively modelling the blast furnaces is significant in ensuring smooth operation and accelerating the digitalisation transformation of blast furnaces. The authors focus on the mechanism modelling of the blast furnace operation process, using a digital twin model development platform to simulate the main reaction processes inside the blast furnaces. Under on‐site production conditions, Si, Mn and Ti contents of molten iron and the corresponding indicators for model accuracy are calculated. For Si, Mn, and Ti content, the Root Mean Square Error values are 0.0678, 0.0108 and 0.0093 for dataset 1, while 0.0933, 0.0120 and 0.0111 for dataset 2, respectively, indicating that the model has a small simulation error and high accuracy. By comparing the simulation results with accurate laboratory results, the model is validated to have satisfactory simulation reliability and compensates for the existing shortcomings in the blast furnace mechanism modelling field.
Compact circularly polarized metasurface antenna based on characteristic mode analysis
Authors: Wang Qing , Lei Xiaopeng , Han Xiaohai , Ge Zhiwei , Lei Zhenya
Published: October 2024

This article introduces a novel, single‐layer, low‐profile, circularly polarized metasurface antenna. Through characteristic mode analysis, the optimization of a 33 rectangular metasurface structure was performed. Two orthogonal modes were selected as the operating modes, and improvements to the metasurface structure were made to achieve a 90 phase difference between these modes. The adoption of a coplanar waveguide structure enables the excitation of the metasurface, facilitating circularly polarized radiation performance for the two selected modes. The antenna's dimensions are 40 mm 40 mm 3 mm (0.67 0.67 0.05 ), featuring a −10 dB impedance bandwidth of 27.8% (4.49–5.94 GHz). The 3 dB axial ratio bandwidth is 14.2% (5.25–6.05 GHz), with a maximum gain of 7.26 dBi.
Map construction algorithm based on dense point cloud
Authors: Liu Chengjie , Li Xuemei , Lv Shangsong , Liu Bin , Li Min
Published: October 2024

In order to address the issue of the difficulty in constructing maps from sensor‐acquired point clouds, a map construction algorithm is proposed for the effective conversion from sparse point clouds to dense point clouds. First, it constructs a dense point cloud map in real‐time using colour and depth information of keyframes. Then, it generates an accurate point cloud map by voxel filtering and coordinate conversion. Finally, the point cloud map is converted into an octree map using OctoMap. This article uses the TUM dataset for simulation analysis to verify the effectiveness of the algorithm. The results demonstrate that the algorithm can construct dense point cloud maps with high positioning accuracy in sparse point cloud scenarios. The algorithm improves the positioning accuracy by more than 15% under the fr1_xyz, fr1_room, fr1_desk2, fr1_desk1, fr2_desk and fr3_str_tex_near sequences, compared to ORB‐SLAM2, ORB‐SLAM3 and GX ORB‐SLAM2 algorithm
Speed control and maximum efficiency operation of three‐phase squirrel cage induction motors supplied by modified Γ−Z$\Gamma - Z$ impedance source inverter
Authors: Yazdani Sajjad , Rajaei Amirhossein , Rahideh Akbar
Published: October 2024

A three‐phase squirrel cage induction motor (IM) drive system supplied by a new modified structure of impedance source inverter ( ISI) is proposed. The two main goals are speed (torque) control, and efficiency improvement. The modified ISI has the ability to boost the input voltage. This improves the operation range of the system particularly for limited DC‐link voltage conditions. A first order integral‐terminal sliding mode (ITSM) controller is designed incorporating the motor and inverter dynamic model equations. The maximum efficiency strategy based on Lagrange's theorem is achieved by optimizing the motor input power (input energy) as the objective function under the constant load torque. The maximum efficiency strategy using energy saving is suitable for electric drive system applications. Also, the control method is resilient to any change in motor parameters and unmodulated system dynamics. Furthermore, its output control error can be eliminated in a limited interval. Finally, a prototype of the system using a 1.5 kW three‐phase squirrel cage IM is provided and several tests are conducted. The experimental results show the efficacy of the proposed method.
Constraints on the accretion properties of quasi-periodic erupters from GRMHD simulations
Authors: Chashkina A. , Bromberg O. , Levinson A. , Nakar E.
Published: October 2024

Context. Some apparently quiescent supermassive black holes (BHs) at centers of galaxies show quasi-periodic eruptions (QPEs) in the X-ray band, the nature of which is still unknown. A possible origin for the eruptions is an accretion disk. However, the properties of such disks are restricted by the timescales of recurrence and the duration of the flares.

Aims. In this work, we test the possibility that the temporal properties of known QPEs can be explained by accretion from a compact accretion disk with an outer radius rout ∼ 40rg, and we focus on a particular object, GSN 069.

Methods. We ran several 3D general relativistic magnetohydrodynamic (GRMHD) simulations with the H-AMR code of thin and thick disks and studied how the initial disk parameters such as thickness, magnetic field configuration, magnetization, and Kerr parameter affect the observational properties of QPEs.

Results. We show that accretion onto a slowly rotating BH through a small, moderately thin accretion disk with an initially low plasma β can explain the observed time between outbursts and the lack of evidence for a variable jet emission. In order to form such a disk, the accreting matter should have a low net angular momentum. A potential source for such low angular momentum matter with a quasi-periodic feeding mechanism might be a tight binary of wind-launching stars. Apart from their primary application, our results can also be useful for general studies of systems with small accretion disks, in which evolution occurs very rapidly so that the disks cannot be considered stationary. For such systems, it is important to understand how the initial conditions affect the results.
Characterisation of the stellar wind in Cyg X-1 via modelling of colour-colour diagrams
Authors: Lai E. V. , De Marco B. , Cavecchi Y. , El Mellah I. , Cinus M. , Diez C. M. , Grinberg V. , Zdziarski A. A. , Uttley P. , Bachetti M. , José J. , Sala G. , Różańska A. , Wilms J.
Published: October 2024

Context. Cygnus X-1 (Cyg X-1) is a high-mass X-ray binary where accretion onto the black hole (BH) is mediated by the stellar wind from the blue supergiant companion star HDE 226868. Due to its inclination, the system is a perfect laboratory to study the not yet well-understood stellar wind structure. In fact, depending on the position of the BH along the orbit, X-ray observations can probe different layers of the stellar wind. Deeper wind layers can be investigated at superior conjunction (i.e. null orbital phases).

Aims. We aim to characterise the stellar wind in the Cyg X-1/HDE 226868 system, analysing one passage at superior conjunction covered by XMM-Newton during the ‘Cyg X-1 Hard state Observations of a Complete Binary Orbit in X-rays’ (CHOCBOX) campaign.

Methods. To analyse the properties of the stellar wind, we computed colour-colour diagrams. Since X-ray absorption is energy-dependent, colour indices provide information on the parameters of the stellar wind, such as the column density, NH, w, and the covering factor, fc. We fitted colour-colour diagrams with models that include both a continuum and a stellar wind component. We used the kernel density estimation method to infer the unknown probability distribution of the data points in the colour-colour diagram, and selected the model corresponding to the highest likelihood. In order to study the temporal evolution of the wind around superior conjunction, we extracted and fitted time-resolved colour-colour diagrams.

Results. We found that the model that best describes the shape of the colour-colour diagram of Cyg X-1 at superior conjunction requires the wind to be partially ionised. The shape of the colour-colour diagram strongly varies during the analysed observation, due to concurrent changes of the mean NH, w and the fc of the wind. Our results suggest the existence of a linear scaling between the rapid variability amplitude of NH, w (on timescales between 10 s and 11 ks) and its long-term variations (on timescales > 11 ks). Using the inferred best-fit values, we estimated the stellar mass loss rate to be ∼7 × 10−6 M⊙ yr−1 and the clumps to have a characteristic mass of ∼1017 g.
Reliabilität und Validität isokinetischer und isometrischer
Krafttests: ein systematisches Review
Authors: Knauer Miriam , Schroeder Jan
Published: October 2024

Hintergrund Isometrische Krafttestungen sind häufig einfacher in der
Anwendung, aber isokinetischen Krafttestresultaten wird eine bessere
Übertragbarkeit auf die Trainingsgestaltung zugeschrieben. Diese
Übersichtsarbeit hat das Ziel, eventuelle Testgüteunterschiede im Sinne von
Validität und Reliabilität bei isometrischer und isokinetischer Krafttestung
herauszuarbeiten.

Material und Methoden Im Januar 2024 wurde die Datenbank PubMed nach
Studien durchsucht, die statistische Kennwerte für die Validität und
Reproduzierbarkeit isokinetischer und isometrischer Krafttestgeräte für gesunde
Erwachsene analysierten. Ausgeschlossen wurden Arbeiten zu speziellen
handgehaltenen Dynamometern oder Veröffentlichungen die älter als 30 Jahren
waren.

Ergebnisse 13 Studien entsprachen den Auswahlkriterien. Isometrische
Maximalkraftmessung erzielten tendenziell höhere
Kurzzeit-Reliabilitätskoeffizienten (ICC: 0,87–0,96) im Vergleich zu
isokinetischen Tests (ICC:0,69–0,99). Die absolute Reproduzierbarkeit war
vergleichbar für Isometrie (CV: 6,9–9,4%, SEM: 4,5–11,0%) und Isokinetik (CV:
2,3–12,4%, SEM: 4,8–14,0%). Die Validität wurde für beide Verfahrensweisen
bestätigt, Validitätskoeffizienten variierten aber stark in Abhängigkeit vom
gewählten Außenkriterium (EMG r>0,9; 5–10-RM r>0,8; Muskelquerschnitt
r>0,7; spezielle isokinetische Vergleichstests r>0,5).

Schlussfolgerungen Bei bestätigter Validität für beide Verfahren
verdeutlicht die aktuelle Evidenzlage, dass Unterschiede in der
Reproduzierbarkeit zwischen Isometrie und Isokinetik vernachlässigbar klein
sind. Zukünftige Forschung sollte sich auf für die Praxis relevante
Nebengütekriterien wie die Zugänglichkeit von populationsspezifischen
Orientierungswerten und die Zeitökonomie bei der Datenerhebung konzentrieren.
Glasgow-Blatchford and Rockall score utility in predicting findings on video capsule endoscopy in patients admitted with overt small bowel bleeding
Authors: Ballester Raquel , O'Connell James , Costigan Conor , Sengupta Shreyashee , Manoharan Thilagaraj , Martinez Monserrat , Mc Namara Deirdre
Published: October 2024

Glasgow-Blachford (GBS) and Rockall scores are recognized tools to prioritize patients with upper gastrointestinal bleeding. Their utility in predicting findings on capsule endoscopy (CE) in patients with overt small bowel bleeding (OSBB) remains unclear. The aim was to assess use of these scores in predicting relevant findings on CE and outcome among patients with suspected OSBB.

A retrospective analysis was performed from January 2019 to June 2022. Clinical parameters and scores were collected at presentation and at 24 hours. Univariate analysis used simple logistic regression, chi-squared test or Mann-Whitney as needed. ROC analysis was performed selecting the optimal cut-off point maximized by the Youden index.

Seventy-nine patients were included, 62% of whom had relevant findings. The predictor showing the highest discrimination ability was the initial GBS (area under the curve [AUC] 0.625; 95% confidence interval [CI] 0.49–0.76). The optimal cut-off point was at least 4, with sensitivity 98%, specificity 30%, and accuracy 72%. Multivariable regression analysis showed inpatient status on CE (odds ratio [OR] 117.27; 95% CI 11.32–4492.93; P = 0.001), shorter time to CE (OR 1.02; CI 1.01–1.04; P = 0.018), higher initial GBS (OR 1.22; CI 1.06–1.43; P = 0.009), and higher GBS within 24 hours (OR 1.19; CI 1.04–1.37; P = 0.013) were predictive factors for relevant findings on CE, with a model AUC 0.802, sensitivity 91.8%, and specificity 63.3%.

GBS and Rockall scores were useful in predicting relevant findings on CE in this cohort of patients with suspected OSBB. In patients with GBS 5 or higher, early CE during the same admission is warranted.
Digital peroral pancreatoscopy to determine surgery for patients who have intraductal papillary mucinous neoplasms of the pancreas with mural nodules
Authors: Koshita Shinsuke , Noda Yutaka , Kanno Yoshihide , Ogawa Takahisa , Kusunose Hiroaki , Sakai Toshitaka , Yonamine Keisuke , Miyamoto Kazuaki , Kozakai Fumisato , Okano Haruka , Matsuoka Yuto , Hosokawa Kento , Sumiya Hidehito , Oikawa Masaya , Tsuchiya Takashi , Sawai Takashi , Ito Kei
Published: October 2024

Background and study aims Because more than a few patients have intraductal papillary mucinous neoplasms of the pancreas (IPMNs) with mural nodules (MNs) that are benign, clinical plans should be determined by using histocytological specimens especially, for patients with high risk for surgery or with a small MN.

Patients and methods This study included 27 patients to evaluate the efficacy of peroral pancreatoscopy using a SpyGlass DS system (POPS-DS) for patients with MN-positive IPMN, mainly focusing on the ability of POPS-DS to detect malignancy.

Results Biopsy specimens obtained under POPS-DS guidance could be used for histological evaluation of all patients with MNs in the main pancreatic duct and 67% of the patients with MNs in the branch ducts, whereas fluid specimens collected during POPS-DS could be used for histocytological evaluation for all patients. For the 13 patients who underwent surgery just after POPS-DS, the sensitivity, specificity, and accuracy of POPS-DS to detect malignancy were 89%, 100%, and 92%, respectively. For the 12 patients who underwent surveillance without surgery, the cumulative 3-year progression rates for nine benign IPMNs and three malignant ones determined using POPS-DS were 0% and 100%, respectively. However, the sensitivity of POPS to detect IPMN epithelium in the resection margin was 20%. Only one patient developed procedure-related pancreatitis (mild).

Conclusions POPS-DS could be used to accurately detect malignancy in patients with MN-positive IPMN. Therefore, histocytological evaluation using POPS-DS can contribute to selection of patients for whom surgery would be appropriate.
External Validation of the fullPIERS Risk Prediction Model in a U.S. Cohort of Individuals with Preeclampsia
Authors: Long Danielle , Flicker Kari , Vishnia Maya , Wright Madeleine , Francis Matilda , King Kenyone S. , Gilgannon Lauren , Rastegar Aref , Gupta Neha , Kousalya Siva Rohini , Nehme Lea , Kawakita Tetsuya
Published: October 2024

Objective This study aimed to externally validate the Preeclampsia Integrated Estimate of Risk (fullPIERS) risk prediction model in a cohort of pregnant individuals with preeclampsia in the United States.

Study Design This was a retrospective study of individuals with preeclampsia who delivered at 22 weeks or greater from January 1, 2010, to December 31, 2020. The primary outcome was a composite of maternal mortality or other serious complications of preeclampsia occurring within 48 hours of admission. We calculated the probability of the composite outcome using the fullPIERS prediction model based on data available within 12 hours of admission, including gestational age, chest pain or dyspnea, serum creatinine levels, platelet count, aspartate transaminase levels, and oxygen saturation. We assessed the model performance using the area under the curve (AUC) of the receiver operating characteristic curve. The optimal cutoff point was determined using Liu's method. A calibration plot was used to evaluate the model's goodness-of-fit.

Results Among 1,510 individuals with preeclampsia, 82 (5.4%) experienced the composite outcome within 48 hours. The fullPIERS model achieved an AUC of 0.80 (95% confidence interval [CI]: 0.75–0.86). The predicted probability for individuals with the composite outcome (median: 18.8%; interquartile range: 2.9–59.1) was significantly higher than those without the outcome (median: 0.9%; interquartile range: 0.4–2.7). The optimal cutoff point of 5.5% yielded a sensitivity of 70.7% (95% CI: 59.6–80.3), a specificity of 85% (95% CI: 82.7–86.5), a positive likelihood ratio of 4.6 (95% CI: 3.8–5.5), and an odds ratio of 13.3 (95% CI: 8.1–21.8). The calibration plot indicated that the model underestimated risk when the predicted probability was below 1% and overestimated risk when the predicted probability exceeded 5%.

Conclusion The fullPIERS model demonstrated good discrimination in this U.S. cohort of individuals with preeclampsia, suggesting it may be a useful tool for health care providers to identify individuals at risk for severe complications.

Key Points
2-Benzimidazolamine-Acetamide Derivatives as Antibacterial Agents: Synthesis, ADMET, Molecular Docking, and Molecular Simulation Studies
Authors: Mazumdar Nasreen Akhtar , Inam Afreen , Akhtar Ayesha , Ali Asghar , Azeem Kashish , Abid Mohammad
Published: October 2024

A series of 2-benzimidazolamine-acetamide derivatives were synthesized by substitution reaction of different anilines with chloroacetyl chloride followed by the reaction of 2-aminobenzimidazole with the formed substituted chloroacetamides. The structures of all the synthesized compounds were elucidated with various spectral techniques and all compounds were evaluated against five bacterial strains. Out of ten, the N-(2-fluorophenyl)-substituted acetamide displayed better minimum inhibitory concentration (MIC). Disk diffusion assay and combination studies were also performed on the same acetamide compound. Molecular docking of this acetamide compound with E. coli methionine aminopeptidase (METAP) displayed effective binding, and molecular dynamics simulation further suggested a stable complex formation. Thus, all these results indicate that these scaffolds can serve as a model for developing antibacterial agents.
An Individualised Homoeopathic Approach to Chronic Atopic Dermatitis: A Case Report
Authors: Mukherjee Suranjana , Sahoo Sanjib
Published: October 2024

Atopic dermatitis is a chronic inflammatory skin disease affecting about one-fifth of all individuals during their lifetime. It has substantial impact on the quality of life of the affected individual. Not only patient is affected by the social stigma of a visible skin condition but also the characteristic itch-scratch cycle often leads to skin trauma and significant sleep disruption. Though there is multitude of treatment options in modern medicine, the recurrence, and adverse effects of medications cannot be ruled out. Therefore, an alternative approach is required. The case presented here reported with the complaint of severe generalised itching eruptions for the last 8 years with a history of atopy. After thorough evaluation from the clinical and homoeopathic standpoint, a single homoeopathic medicine Arsenicum iodatum was prescribed in different potencies at different timepoints as the symptomatology corresponds. Following the administration of individualised homoeopathic (IH) medicine, there was gradual improvement in the case with disappearance of skin lesions which was also evaluated through reduction in SCORing Atopic Dermatitis and Dermatology Life Quality Index scores. During the treatment, old symptoms also reappeared indicating improvement in accordance with Hering's law of cure and Kent's 11th observation. The modified Naranjo criteria score after the treatment course was 10 which exclusively shows positive causal attribution of the IH in this case.
Rheumatoid Arthritis and Pregnancy: Managing Disease Activity and Fertility Concerns
Authors: Marcy Daniele , Zell JoAnn , Demoruelle M. Kristen
Published: October 2024

Rheumatoid arthritis (RA) is a systemic autoimmune disease that more commonly affects women, including many women during the childbearing years. This can make management challenging for practitioners involved in the care of these patients. This review article will discuss the available data and expert recommendations pertaining to women with RA who are pregnant or planning pregnancy. Herein, we will consider pregnancy complications associated with RA, the benefits of maintaining low disease activity prior to conception and throughout pregnancy, flare management during pregnancy, ensuring pregnancy-compatible medications to treat RA, and the reduced rates of fertility in patients with RA. While research in this area has greatly expanded over the past decade, it continues to be an area where more research is needed to best support women with RA as they navigate pregnancy.
Signatures of coherent vibrational dynamics in ethylene carbonate
Authors: Guerrieri Luke , Hall Sarah , Luther Brad M. , Krummel Amber T.
Published: October 2024

Despite having practical applications in battery technology and serving as a model system for Fermi resonance coupling, ethylene carbonate (EC) receives little direct attention as a vibrational probe in nonlinear vibrational spectroscopy experiments. EC contains a Fermi resonance that is well-characterized in the linear spectrum, and the environmental sensitivity of its Fermi resonance peaks could make it a good molecular probe for two-dimensional infrared spectroscopy (2DIR) experiments. As a model system, we investigate the linear and 2DIR vibrational spectrum of the carbonyl stretching region of ethylene carbonate in tetrahydrofuran. The 2DIR spectrum reveals peak dynamics that evolve coherently. We characterize these dynamics in the context of Redfield theory and find evidence that EC dynamics proceed through coherent pathways, including singular coherence transfer pathways that have not been widely observed in other studies. We find that coherent contributions play a significant role in the observed dynamics of cross-peaks in the 2DIR spectrum, which must be accounted for to extract accurate measurements of early waiting time dynamics.
Artificial-intelligence-driven shot reduction in quantum measurement
Authors: Liang Senwei , Zhu Linghua , Liu Xiaolin , Yang Chao , Li Xiaosong
Published: October 2024

Variational Quantum Eigensolver (VQE) provides a powerful solution for approximating molecular ground state energies by combining quantum circuits and classical computers. However, estimating probabilistic outcomes on quantum hardware requires repeated measurements (shots), incurring significant costs as accuracy increases. Optimizing shot allocation is thus critical for improving the efficiency of VQE. Current strategies rely heavily on hand-crafted heuristics requiring extensive expert knowledge. This paper proposes a reinforcement learning (RL)-based approach that automatically learns shot assignment policies to minimize total measurement shots while achieving convergence to the minimum of the energy expectation in VQE. The RL agent assigns measurement shots across VQE optimization iterations based on the progress of the optimization. This approach reduces VQE's dependence on static heuristics and human expertise. When the RL-enabled VQE is applied to a small molecule, a shot reduction policy is learned. The policy demonstrates transferability across systems and compatibility with other wavefunction Ansätze. In addition to these specific findings, this work highlights the potential of RL for automatically discovering efficient and scalable quantum optimization strategies.
Ultraviolet spectral broadening by stimulated rotational Raman scattering on nitrogen pumped with signal laser injection
Authors: Wang Xiangbing , Chai Xiangxu , Li Ping , Zhang Bo , Zhu Qihua , Tian Xiaocheng , Wang Ju , Zong Zhaoyu , Zhou Song , Yao Ke , Li Sen , Zhao Junpu , Peng Zhitao
Published: October 2024

We present experimental results on kilojoule ultraviolet laser output with 1% spectral broadening. Through stimulated rotational Raman scattering (SRRS) with signal laser injection, we achieve effective spectral broadening in short-range propagation, with good retention of the original near-field distribution and time waveform. Theoretical calculations show that 2% bandwidth spectral broadening can be achieved by injecting 20 kW/cm2 signal light at 2.2 GW/cm2 flux of the pump laser. In addition, high-frequency modulation in the near field can be effectively avoided through replacement of the original random noise signal light by the controllable signal light. The SRRS in the atmospheric environment excited with signal laser injection can provide wide-band light output with controllable beam quality without long-distance propagation, representing an important potential route to realization of broadband laser drivers.
Perturbation-response dynamics of coupled nonlinear systems
Authors: Börner Georg , Schröder Malte , Thümler Moritz , Timme Marc
Published: October 2024

How nonlinear systems dynamically respond to external perturbations essentially determines their function. Weak perturbations induce response dynamics near a stable operating point, often approximately characterized by linear response theory. However, stronger driving signals may induce genuinely nonlinear responses, including tipping transitions to qualitatively different dynamical states. Here, we analyze how inter-unit coupling impacts responses to periodic perturbations. We find that already in minimal systems of two identical and linearly coupled units, coupling impacts the dynamical responses in a distinct way. Any non-zero coupling strength extends the regime of non-tipping local responses relative to uncoupled units. Intriguingly, finite coupling may be more effective than infinitely strong coupling in keeping responses from tipping. Interestingly, already weak coupling may create novel response modes in strongly driven systems, implying the existence of multiple tipping points instead of only one. These results persist for systems of non-identical units, systems with nonlinear coupling, and larger networks of coupled units.
Numerical simulation of particles distribution of environmental tobacco smoke (ETS) and its concentration in a closed environment
Authors: Mohammadpoor Elaheh , Bakhshan Younes
Published: October 2024

Humans are frequently exposed to various chemical hazards, with smoking being a significant source of indoor air pollution. This pollution is particularly pronounced in environments such as smoking rooms, conference halls, cafes, and coffee houses. This study focuses on analyzing the concentration, distribution, and behavior of emitted particles from both mainstream and sidestream smoke in a controlled smoking room environment. A critical aspect of the research is the consideration of the thermal plume generated by the smoker's body, particularly around the breathing zone, which plays a crucial role in the dispersion and inhalation of pollutants. To conduct this analysis, a computational fluid dynamics approach was employed, incorporating a displacement ventilation (DV) system integrated with a detailed surface mesh model of a standing manikin. A Lagrangian approach was utilized to track the particle paths, considering factors such as particle size, density, and initial velocity. This approach was complemented by an Eulerian method to simulate the complex airflow patterns within the smoking room, accounting for turbulent flow and temperature variations. The integration of these methods provides a comprehensive understanding of both the macroscopic and microscopic behaviors of smoke particles. The motion equations governing the particles incorporated several forces, including inertial drag force, viscous drag force, buoyancy force, and gravitational force. Additionally, the study examined the interaction between thermal plumes and smoke particles, particularly how temperature gradients around the body affect particle dispersion and concentration. The study meticulously evaluated the distribution and volume average of respirable suspended particles (RSPs) and nicotine by analyzing a plane opposite to the breathing zone of both heated and unheated manikins. It was observed that the thermal plume generated by the temperature gradient around the body could significantly alter the flow field of both sidestream and mainstream smoke between puff periods. The simulation results demonstrated that the thermal plume increased the concentration of RSPs in the breathing zone, highlighting a critical exposure pathway for smokers and nonsmokers alike. A significant increase of approximately 70% in the nicotine concentration is due to the thermal plume. The concentration of nicotine peaks at approximately 0.003 mg/m3 by the third second in smoker#1's (6 smokers' position) breathing zone. Specific configurations of the DV system showed varying efficiencies in reducing pollutant concentrations, emphasizing the need for targeted ventilation strategies. In a chamber with six smokers, researchers found that the time required for suspended particles to reach a cleaning ratio, considering the dynamics of particle movement due to smoking activity, was approximately 184 s per puff.
Small tensor product distributed active space (STP-DAS) framework for relativistic and non-relativistic multiconfiguration calculations: Scaling from 109 on a laptop to 1012 determinants on a supercomputer
Authors: Hu Hang , Upadhyay Shiv , Lu Lixin , Jenkins Andrew J. , Zhang Tianyuan , Shayit Agam , Knecht Stefan , Li Xiaosong
Published: October 2024

Despite the power and flexibility of configuration interaction (CI) based methods in computational chemistry, their broader application is limited by an exponential increase in both computational and storage requirements, particularly due to the substantial memory needed for excitation lists that are crucial for scalable parallel computing. The objective of this work is to develop a new CI framework, namely, the small tensor product distributed active space (STP-DAS) framework, aimed at drastically reducing memory demands for extensive CI calculations on individual workstations or laptops, while simultaneously enhancing scalability for extensive parallel computing. Moreover, the STP-DAS framework can support various CI-based techniques, such as complete active space (CAS), restricted active space, generalized active space, multireference CI, and multireference perturbation theory, applicable to both relativistic (two- and four-component) and non-relativistic theories, thus extending the utility of CI methods in computational research. We conducted benchmark studies on a supercomputer to evaluate the storage needs, parallel scalability, and communication downtime using a realistic exact-two-component CASCI (X2C-CASCI) approach, covering a range of determinants from 109 to 1012. Additionally, we performed large X2C-CASCI calculations on a single laptop and examined how the STP-DAS partitioning affects performance.
Elastic constants from charge density distribution in FCC high-entropy alloys using CNN and DFT
Authors: Mirzaee Hossein , Soltanmohammadi Ramin , Linton Nathan , Fischer Jacob , Kamrava Serveh , Tahmasebi Pejman , Aidhy Dilpuneet
Published: October 2024

While high-entropy alloys (HEAs) present exponentially large compositional space for alloy design, they also create enormous computational challenges to trace the compositional space, especially for the inherently expensive density functional theory calculations (DFT). Recent works have integrated machine learning into DFT to overcome these challenges. However, often these models require an intensive search of appropriate physics-based descriptors. In this paper, we employ a 3D convolutional neural network over just one descriptor, i.e., the charge density derived from DFT, to simplify and bypass the hunt for the descriptors. We show that the elastic constants of face-centered cubic multi-elemental alloys in the Ni–Cu–Au–Pd–Pt system can be predicted from charge density. In addition, using our recent PREDICT approach, we show that the model can be trained only on the charge densities of simpler binary and ternary alloys to effectively predict elastic constants in complex multi-elemental alloys, thereby further enabling easier property-tracing in the large compositional space of HEAs.
Physicochemical properties of the confined hydrogen atom under dense semiclassical hydrogen plasma
Authors: Das Biswajit , Das Netai , Ghoshal Arijit
Published: October 2024

Some fundamental quantities governing the physicochemical properties of the spherically confined (contained in a spherical box) hydrogen atom embedded in dense semiclassical hydrogen plasma have been investigated. These quantities specifically include the energy levels, wavefunctions, 2k-pole oscillator strength, 2k-pole polarizability, hyperfine spitting, effective pressure on the boundary of the confining surface. The effect of plasma is described by a pseudopotential which takes care of the collective effect and the quantum mechanical effects at short distances of the plasma particles by means of two adjustable parameters, namely, the screening parameter and the de Broglie wavelength. Energy eigenvalues of the atom for various box sizes and for different values of the plasma parameters are computed accurately within a variational framework by employing a large wavefunction which automatically takes care of the requisite boundary conditions. Convergence of the computed results is corroborated by increasing the number of terms in the wavefunction. Particular attention is paid on determining the critical size box for which all the bound states of the atom cease to exist. Based on the computed energies and the corresponding eigenfunctions, mean values of various powers of the radial coordinate, oscillator strengths, polarizability of various order, hyperfine splitting, and the effective pressure on the boundary have been evaluated. A comprehensive study is made on the changes of those quantities for varying box size and plasma parameters. Efforts are made to distinguish the changes arising out of the spatial confinement and the plasma confinement.
Investigating the correlation between flow dynamics and flow-induced voltage generation
Authors: Takeda Hikaru , Iwamoto Naoya , Honda Mitsuhiro , Tanemura Masaki , Yamashita Ichiro , Komiya Atsuki , Okada Takeru
Published: October 2024

The conversion of water current to voltage generation through graphene has gained interest in both basic physics and applications such as sensors and electricity generation systems. However, many aspects of the mechanism remain unclear. Recently, quantum-based momentum transfer theories have been reported, but these often do not account for flow conditions. In this study, we investigated the correlation between the flow conditions of a liquid medium and the electrical conduction of graphene through experiments and numerical calculations. Our results suggest that the necessary condition is that the flow must be neither irregular nor purely laminar; instead, graphene responds to the transition process of the fluid. This finding supports the extension of current theories and presents valuable insights for both basic science and industrial applications.
A simple model for frequency up-conversion in linear time-variant gaseous plasmas
Authors: Mehrpour Bernety Hossein , Cappelli Mark A.
Published: October 2024

We present a simple model to estimate electromagnetic wave frequency up-conversion resulting from rapidly forming gaseous plasma slabs. Such a model aids in the interpretation or planning of realizable laboratory experiments, where the plasma is neither formed instantaneously nor infinite in spatial extent. The model uses, as a basis, the behavior of an unbounded plasma when the plasma forms over extended times and considers slab boundary conditions to estimate optimum transmitted sampling windows that capture the frequency spectra of the converted waves. The results of this model are compared to exact solutions using finite difference time domain calculations, confirming its effectiveness as a tool for understanding the fundamental nature of the wave-plasma slab interactions and for planning and interpreting experimental results.
Turbulence with associated kinetic energy budget in the region of wave-blocking formed over an obstacle
Authors: Chatterjee Debasmita , Mazumder B. S. , Ghosh Subir , Debnath K.
Published: October 2024

Turbulence characteristics in the region of wave-blocking over a submerged forward-facing obstacle is explored, and the results are compared with those of base-flow over the obstacle. Wave-blocking over obstacle is setup, adjusting the strong incoming flow with counter-propagating waves, and confirmed by linear dispersion relation. A variation in the flow is detected in three distinct segments: flow from the upstream, wave-blocking over the obstacle and the waves propagating from the downstream. The instantaneous velocity is recorded using a three-dimensional micro-acoustic Doppler velocimeter along the flow. Turbulence properties such as the mean velocity, Reynolds stress, turbulent kinetic energy, and associated coherent structures around the wave-blocking are discussed. Moreover, power spectral density, kinetic energy budget, and turbulence length- and time-scales are examined. The stress fractions to the total shear stress contribute higher for only flow than those of wave-blocking over obstacle. The power-spectral peaks at a fixed frequency for wave-blocking along lee side are greater than those of base-flow over obstacle. Kinetic energy budget for only flow over the obstacle is much higher than that of wave-blocking, indicating loss of energy due to wave-blocking. In the near-bed region, length-scale increases indicating the higher momentum and energy transfer. Increase in anisotropy plays significant role in the production. Results are valuable to ship sailing, design of coastal structures, and sediment transport.
Room-temperature modulation of microwave conductivity in ferroelectric-gated correlated oxides
Authors: Chu Shizai , Hao Yifei , Feng Shaopeng , Hong Xia , Lai Keji
Published: October 2024

We report the nonvolatile modulation of microwave conductivity in ferroelectric PbZr0.2Ti0.8O3-gated ultrathin LaNiO3/La0.67Sr0.33MnO3 correlated oxide channel visualized by microwave impedance microscopy. Polarization switching is obtained by applying a tip bias above the coercive voltage of the ferroelectric layer. The microwave conductivity of the correlated channel underneath the up- and down-polarized domains has been quantified by finite-element analysis of the tip-sample admittance. At room temperature, a resistance on/off ratio above 100 between the two polarization states is sustained at frequencies up to 1 GHz, which starts to drop at higher frequencies. The frequence-dependence suggests that the conductance modulation originates from ferroelectric field-effect control of carrier density. The modulation is nonvolatile, remaining stable after 6 months of domain writing. Our work is significant for potential applications of oxide-based ferroelectric field-effect transistors in high-frequency nanoelectronics and spintronics.
Performance of an oscillating water column wave energy converter device under random ocean waves and ocean currents
Authors: Dash Santanu Kumar , Koley Santanu , Zheng Siming
Published: October 2024

The present study investigates the hydrodynamic performance of an onshore oscillating water column (OWC) device placed over an undulated bottom topography by analyzing its hydrodynamic efficiency under the action of combined wave–current interaction. The classical small-amplitude water wave theory is used to model the physical problem. The constant boundary element method is employed to solve the boundary value problem. Significant attention is devoted to describing the hydrodynamic parameters associated with the OWC device by considering the mutual combination of the random waves and ocean currents in the wave propagation phenomena. To examine the complex dynamics of the combined irregular wave current phenomena, the Det Norske Veritas spectrum accompanied by a suitable sea state has been considered for the present study. Considering the existence of opposing and following currents in wave propagation, a comprehensive analysis is conducted on the interactions of regular and irregular water waves with the OWC device. The simulated results demonstrate that the presence of ocean currents in the wave propagation phenomenon strongly influences the resonating patterns of the efficiency and force curves. Additionally, the Doppler shift in the apparent frequency caused by the following currents in the random wave–current interaction significantly improves the device's efficiency for an appropriate structural design.
From Darcy to turbulent flow: Investigating flow characteristics and regime transitions in porous media
Authors: Abdi R. , Krzaczek M. , Abdi M.
Published: October 2024

This research addresses the flow characteristics within a porous medium composed of a monolayer of closely packed spheres, spanning from viscous-dominated to turbulent flow regimes. In the first part of this paper, the turbulent flow characteristics at a 30 MPa pressure drop within the domain are presented. The results are averaged across different cross sections between the inlet and outlet. In the second part of the study, simulations are conducted with pressure drops, ranging from nearly 0 to 100 MPa. The analysis finds distinct flow patterns within the domain and provides estimations for the permeability and the inertial term coefficient. Moreover, the transition from Darcy to non-Darcy and turbulent flow is achieved through the use of different criteria. The specified geometry is suitable for validating and calibrating simplified discrete element method models coupled with computational fluid dynamics. The main goal of this research is to produce a reliable benchmark to figure out the challenge of limited experimental data concerning fluid flow characteristics in densely packed granules specially subjected to high pressure conditions. To do this, representative specimens are designed, accurate simulations are conducted, and precise assessments of the results are carried out.
Multiscale analysis of Reynolds stresses and its dissipation rates for premixed flame–wall interaction
Authors: Ghai Sanjeev Kumar , Ahmed Umair , Chakraborty Nilanjan , Klein Markus
Published: October 2024

Direct numerical simulation (DNS) data of flame–wall interaction (FWI) has been utilized to analyze the multiscale nature of turbulent Reynolds stresses and dissipation rate tensor anisotropies within turbulent reacting flow boundary layers across a broad range of scales. The DNS data of head-on quenching of premixed flames propagating through turbulent boundary layers, representative of friction Reynolds numbers Reτ of 110 and 180, has been explicitly filtered using both two- and three-dimensional Gaussian filter kernels for the purpose of multiscale analysis. The low-pass filter results demonstrate the transition from a 2-component limit to a 1-component limit near the wall with increasing filter width, accompanied by a decrease in isotropy, suggesting a significant alteration in dominant flow patterns and a diminishing tendency toward isotropy. The high-pass filter results indicate a progressive increase in anisotropy with the progress of FWI at the channel center, emphasizing the anisotropy of the large scales with the progress of FWI. Furthermore, behaviors of the second and third invariants of the Reynolds stress tensor remain qualitatively similar to that of the dissipation rate tensor at all stages of FWI, suggesting a link between viscous dissipation and Reynolds stress distributions; notably, there is a stronger isotropic tendency in the dissipation rate tensor when the flame is away from the wall, intensifying with an increase in Reynolds numbers. However, as FWI progresses, the shift in the trend toward the 1-component limit indicates an increase in anisotropy within the turbulent reacting flow for the region near the center of the channel.
Physics-informed neural networks for inversion of river flow and geometry with shallow water model
Authors: Ohara Y. , Moteki D. , Muramatsu S. , Hayasaka K. , Yasuda H.
Published: October 2024

The river flow transports sediment, resulting in the formation of alternating sandbars in the riverbed. The underlying physics is characterized by the interaction between flow and river geometry, necessitating an understanding of their inseparable relationship. However, the dynamics of river flow with alternating sandbars are hard to understand due to the difficulty of measuring flow depth and riverbed geometry during floods with current technology. This study implements an innovative approach utilizing physics-informed neural networks (PINNs) to estimate important hydraulic variables in rivers that are difficult to measure directly. The method uses sparse yet obtainable flow velocity and water level data. The governing equations of motion, continuity, and the constant discharge condition based on the mass conservation principle are integrated into the neural network as physical constraints. This approach enables the completion of sparse velocity fields and the inversion of flow depth, riverbed elevation, and roughness coefficients without requiring direct training data for these variables. Validation was performed using model experiment data and numerical simulations derived from these experiments. Results indicate that the accuracy of the estimations is relatively robust to the number of training data points, provided their spatial resolution is finer than the wavelength of the sandbars. The inclusion of mass conservation as a redundant constraint significantly improved the convergence and accuracy of the model. This PINNs-based approach, using measurable data, offers a new way to quantify complex river flows on alternating sandbars without significant updates to conventional methods, providing new insights into river physics.
Identification of incipient cavitation in control valve
Authors: Jablonská J. , Blejchař T. , Mahdal M. , Kozubková M. , Hružík L. , Kolář D.
Published: October 2024

Control valves as important elements in hydraulic systems are used to transport liquid and gaseous media, for example, water, water vapor, and hydrogen. They are mainly used in the power engineering, chemical industry, and so forth. Due to their large dimensions, the verification of hydraulic parameters is problematic. In the case of liquid flow, cavitation can occur, which is mainly characterized by noise, vibrations, or changes of hydraulic parameters. During the incipient cavitation in the valve, there are no noticeable changes in the hydraulic characteristics. The article, therefore, deals with the methodology of determining the cavitation by measuring and evaluating the characteristics of the valve, spectral analysis of noise, and vibrations during water flow. Mathematical modeling is also a suitable tool for determining the extent of cavitation in valve design. Newly created modified cavitation model, where the flowing medium is defined as a mixture of incompressible water and compressible gases (vapor and air), better corresponds to physical principles than the two-phase approach (water and vapor) with experimentally modified density and viscosity. Measured noise and vibration frequency characteristics and mathematically modeled pressure frequency characteristics identify cavitation in the (1 to 10) kHz range. The article proves that when identifying cavitation, the method of measuring hydraulic characteristics fails, but the method of measuring noise and vibrations is suitable in practice, i.e., in real industrial equipment, and the modified cavitation model is suitable for identifying cavitation regions in structural designs of the hydraulic elements.