Miracle-dz/UniFAR-FTUs huggingface dataset:
Similarity and dynamic similarity models for large-eddy simulations of a rotating convection-driven dynamo

SUMMARY Numerical simulations of rotating convection-driven dynamos have been found very useful to understand the inner workings of the geodynamo. Parametrization of small-scale processes can allow the simulations to approach a more realistic parameter range provided that these processes are modelled properly. In line with this effort, two turbulent models, the scalesimilar model of Bardina et al. and a dynamic similarity model, have been applied to a rotating convection-driven plane-layer dynamo simulation with an infinite Pr number in this paper. The results from the similarity model are satisfactory: the large-scale magnetic/kinetic energies and rms magnetic/velocity field fluctuations are in much better agreement with the highly resolved solution than with the low-resolution direct simulation. The model is found to be much less sensitive to the filter scale than the a priori test. Implementation of a dynamic procedure to the similarity model gives better agreement provided that the two filtering scales are properly chosen. Effect of aspect ratio on the performance of the models is also studied by carrying out simulations with aspect ratio 1 and 2. The results show that performances of the models are not influenced by the aspect ratio chosen.
DETERMINATION OF EDGES OF A CONVEX POLYTOPE

In this paper, the problem of determination of the edges of a convex polytope is considered. It is shown that this problem is equivalent to the standard linear programming problem and therefore can be solved by the simplex method. Further, for a special type of polytopes which are an affine transformation of a box we show that extremal points determine edges
Precise simulation of subcritical freezing using constrained cell models

In simulations of freezing transitions using constrained cell models, the space is divided into Wigner–Seitz cells appropriate for the solid phase under consideration and each particle is confined to move in its own Wigner–Seitz cell. The constrained cell model is a limiting case of a generalized or modified cell model which is constructed by adding a homogeneous external field that controls the relative stability of the two phases. High values of the external field variable force configurations with one particle per Wigner–Seitz cell and thus favor the solid phase. Normal (i.e. unconstrained) behavior is recovered in the limit of vanishing field. In previous work, it was shown that the modified cell model can be used to link the fluid with the solid phase on a constant-pressure (or density) path by progressively increasing the strength of the field. It was found that the passage from the fluid to the solid is continuous at low and moderate pressures. In contrast, at high pressures, the passage from the fluid to the solid occurs via a discontinuous, first-order transition. The special point that separates continuous from discontinuous behaviors is very close to the mechanical stability point of the solid phase. In previous work, the fluid–solid transition of model systems on supercritical isotherms was determined either by analyzing the field-induced transition of the appropriate modified cell model in the zero-field limit or via thermodynamic integration using the same model. In the present work, the fluid–solid transition of the Lennard-Jones model is analyzed on the isotherm that corresponds to a reduced temperature of unity. At this temperature, the pressure-density isotherm of the fluid phase contains a first-order gas–liquid phase transition. Constant-pressure simulations of the constrained cell model indicate that the pressure-density isotherm of the solid phase contains a similar phase transition between a dilute, gas-like and a dense, liquid-like phase, respectively. The ‘gas–liquid’ phase transition of the constrained cell model terminates at a critical point. The fluid–solid transition of the Lennard-Jones model at a reduced temperature of unity is obtained from constant-pressure simulations of the appropriate modified cell model. The size-dependent coexistence pressure and densities are analyzed according to finite-size scaling techniques. As was also emphasized in previous work, the results clearly demonstrate the importance of accounting for size effects in simulations of fluid–solid transitions.
Iterative methods for optimization

This book presents a carefully selected group of methods for unconstrained and bound constrained optimization problems and analyzes them in depth both theoretically and algorithmically. It focuses on clarity in algorithmic description and analysis rather than generality, and while it provides pointers to the literature for the most general theoretical results and robust software, the author thinks it is more important that readers have a complete understanding of special cases that convey essential ideas. A companion to Kelley's book, Iterative Methods for Linear and Nonlinear Equations (SIAM, 1995), this book contains many exercises and examples and can be used as a text, a tutorial for self-study, or a reference. Iterative Methods for Optimization does more than cover traditional gradient-based optimization: it is the first book to treat sampling methods, including the Hooke& Jeeves, implicit filtering, MDS, and Nelder& Mead schemes in a unified way.
Features of artificial ionosphere turbulence induced by the O- and X-mode HF heating near the F2-layer critical frequency

We present experimental results from the studies of large-scale inhomogeneities along the external magnetic field with increased electron density, electron temperature, and excitation of elongated plasma waves (Langmuir and ion-acoustic), induced by the ordinary (O-mode) and extraordinary (X-mode) HF heating near the F2-layer critical frequency, in the high-latitude ionospheric F-region. The experiments have been carried out at the EISCAT/Heating facility (Tromsø, Norway). Powerful HF radio waves radiated towards the magnetic zenith through a step change in the effective radiated power at frequencies fH near and below the F2-layer critical frequency fₒF2. The EISCAT incoherent scatter radar (930 MHz), co-located with the EISCAT/Heating facility, was utilized for diagnostics of ionospheric modification effects. We calculated the electric field of a powerful HF radio wave near the reflection altitude, taking into account the non-deflective absorption along the propagation path. We determined the conditions for electric field generation and its threshold (minimum) values required for electron density enhancements in a wide altitude range, excitation of Langmuir and ion-acoustic plasma waves under fH~fₒF2 and fH<fₒF2. The possible generation mechanisms for the electron density enhancements above the reflection altitude of the powerful HF radio wave of O- and X-polarization are discussed.
Jet Impingement Heat Transfer from a Circular Cylinder Located Between Confining Walls

*The heat transfer characteristics of a circular cylinder (diameter d) located between confining walls (at varying separation distance H apart) exposed to slot jet of air (of width w) from a contoured nozzle, and at a range of spacing z from the jet exit, has been studied experimentally and computationally. The study focussed on Reynolds number Re in the range 1000 – 12000. The results reveal that while the slot jet impinging on a cylinder in confined space generally yields higher average heat transfer rates relative to the uniform cross flow case; these are however almost always found to yield lower heat transfer rates in comparison with corresponding slot jet impingement without confining walls. Furthermore, in the Reynolds number range studied, it was found that a dimensionless confinement spacing H/d = 10 exists which consistently exhibits a minimum in cylinder heat transfer rate over all the non-dimensional jet exit to cylinder spacing z/w and ratio of cylinder diameter to slot width d/w that were investigated. It was established that reduction in heat transfer for confinements H/d between 10 and 16 is due to the jet becoming unstable and thereby periodically flapping across the cylinder, switching between the confining walls, in tandem with vortex shedding from the cylinder. This reduces the effectiveness of impingement and hence reduces the heat transfer rates. It is therefore concluded that jet impingement does not always enhance heat transfer rate, but may in fact reduce it under conditions in which the impingement target is located in the midst of confining walls. It was observed that the average of all the Nusselt numbers in a confined space reduces by about 17% when compared with a non confined cylinder. In summary therefore, the influence of confining walls around the cylinder has an unfavourable impact on the flow and therefore the heat transfer rates with jet impingement. The reduction in heat transfer rates with confining walls implies that a jet impingement heat transfer system designed using data obtained for jet impingement on a non-confined cylinder could compromise the effectiveness of the system, and may have a large bearing on the quality, efficiency and productivity as well as on the health and safety aspects of products and processes.
Non-linear capillary waves generated by steep gravity waves

The train of capillary waves which appears on the forward face of a steep gravity wave is discussed by considering the capillary waves as stationary waves on a slowly varying running stream, using the non-linear capillary wave solution of Crapper (1957) and the recent method due to Whitham (1965a, b). Then energy input and damping are introduced into an energy equation which becomes a non-linear ordinary differential equation for the capillary wave steepness. Numerical solutions for various gravity wavelengths and steepnesses are discussed, and some light is thrown on the problem of the breaking of gravity waves.
Doped conducting-polymer-semiconducting-polymer interfaces: Their use in organic photovoltaic devices

We report a study of the interface between poly(p-phenylene vinylene) (PPV) and poly(ethylene dioxythiophene) doped with polystyrene sulfonic acid (PEDOT:PSS). We find from measurements of optical absorption and conductivity that PSS dopes PPV during the sample preparation. In addition, the photoluminescence efficiency of PPV is strongly affected by the presence of PSS which we attribute to the effect of chemical doping. We further studied the interaction between PSS and PPV by measurements of the photovoltaic response, spectrally resolved, of a number of diode structures. By forming the interface between a layer of PEDOT:PSS and a layer of PPV precursor prior to the thermal conversion we obtained an interpenetrating interface with large surface area between the photoresponsive and the charge collecting polymers. For devices made with PEDOT:PSS as top electrode and aluminum as the bottom electrode the short-circuit external quantum efficiency is 4%.
Effects of adding functionalized graphene oxide nanosheets on physical, mechanical, and anti-biofilm properties of acrylic resin: In vitro- experimental study

Background: Polymethyl methacrylate resin is widely used in orthodontic treatments. Graphene oxide (GO) has reactive functional groups on its surface that facilitate binding to various materials such as polymers, biomolecules, DNA, and proteins. This study aimed to investigate the impact of adding functionalized GO nanosheets on the physical, mechanical, cytotoxicity, and anti-biofilm properties of acrylic resin. Materials and Methods: In this experimental study, fifty samples (for each test) were divided into groups of 10, in the form of acrylic resin discs with concentrations of 0, 0.25, 0.5, 1, and 2 weight percentage (wt%) of functionalized GO nanosheets and also the control group. Samples were evaluated in terms of physical properties (surface hardness, surface roughness, compressive strength, fracture toughness, and flexural strength), anti-biofilm properties (On four groups of micro-organisms, including Streptococcus mutans, Streptococcus sanguis, Staphylococcus aureus, and Candida albicans), and cytotoxicity. Data were analyzed using SPSS software version 22, descriptive statistics, one-way analysis of variance test, and Tukey post hoc test. The significance level was considered P < 0.05. Results: No significant difference was observed between the different groups with weight percentages of 0.25, 0.5, 1, and 2% nano GO (nGO) and the control group (without nGO) in terms of surface roughness and toughness. However, compressive strength, three-point flexural strength, and surface hardness showed significant differences between the groups. Furthermore, the degree of cytotoxicity increased by increasing the weight percentage of nano-GO. Conclusion: The addition of functionalized nGO in appropriate concentrations to polymethyl methacrylate can improve the anti-bacterial and anti-fungal biofilm properties without changing or increasing their physical and mechanical properties.
Observation and interpretation of the photoionization cross section of the neutral iron atom (Fe I)

The relative photoionization cross section of the neutral iron atom has been determined in the region 1575 to 1150 AA using a crossed-beam photoelectric technique. The resonances observed below 1400 AA have been interpreted as being due to transitions of the type (3d6 5D)4s2 to 3d54s2np (n=4 and 5). Hartree-Fock and intermediate-coupling calculations of the structure of the 3d54s2np configurations have been carried out and the interpretation has been based on calculations of the transition probabilities for the 3d to np excitations. Resonances observed in the region between the first ionization limit at 1575 AA and 1400 AA are interpreted as due to (3d6 5D)4s2 to (3d6 5D)4s 4D np transitions.
Optimization of radome wall and joint for X-band reflector antenna using Floquet modal analysis

The performance of high frequency weather radars becomes questionable when the antenna system is enclosed by a radome because losses are more at higher frequency. To achieve high performance and accuracy, the radome wall and joints should be designed and optimized properly. Current manuscript presents the detailed study of A-sandwich radome wall and joint characteristics derived for polarimetric Doppler Weather Radar reflector antenna at X-band frequency. The diameter of the reflector antenna is 2.4 m which will be protected by a spherical A-sandwich radome of diameter 4.2 m. Radome wall is optimized by parametric variation of skin and core thickness using Floquet’s modal analysis in Ansoft HFSS Software package. Performances of radome panel with three different joint cross-sections have been compared in terms of insertion loss and phase variation and the best one is proposed for X-band antenna radome. Measurement was carried out at Compact Antenna Test Facility where the joint of two flat rectangular radome panels was hanged vertically in front of reflector antenna. Simulated results are compared with measured results to validate the proposed design.
Simulation of Turbulent Flows Using a Finite-Volume Based Lattice Boltzmann Flow Solver

In this study, the Lattice Boltzmann Method (LBM) is implemented through a finite-volume approach to perform 2-D, incompressible, and turbulent fluid flow analyses on structured grids. Even though the approach followed in this study necessitates more computational effort compared to the standard LBM (the so called stream and collide scheme), using the finite-volume method, the known limitations of the stream and collide scheme on lattice to be uniform and Courant-Friedrichs-Lewy (CFL) number to be one are removed. Moreover, the curved boundaries in the computational domain are handled more accurately with less effort. These improvements pave the way for the possibility of solving fluid flow problems with the LBM using coarser grids that are refined only where it is necessary and the boundary layers might be resolved better.
Dust Effect on the Performance of Wind Turbine Airfoils

The full two-dimensional Navier-Stokes algorithm and the SST k-? turbulence model were used to investigate incom-pressible viscous flow past the wind turbine two-dimensional airfoil under clean and roughness surface conditions. The NACA 63-430 airfoil is chosen to be the subject, which is widely used in wind turbine airfoil and generally located at mid-span of the blade with thickness to chord length ratio of about 0.3. The numerical simulation of the airfoil under clean surface condition has been done. As a result, the numerical results had a good consistency with the experimental data. The wind turbine blade surface dust accumulation according to the operational periods in natural environment has been taken into consideration. Then, the lift coefficients and the drag coefficients of NACA 63-430 airfoil have been computed under different roughness heights, different roughness areas and different roughness locations. The role that roughness plays in promoting premature transition to turbulence and flow separation has been verified by the numeri-cal results. The trends of the lift coefficients and the drag coefficients with the roughness height and roughness area increasing have been obtained. What’s more, the critical values of roughness height, roughness area, and roughness location have been proposed. Furthermore, the performance of the airfoil under different operational periods has been simulated, and an advice for the period of cleaning wind turbine blades is proposed. As a result, the numerical simula-tion method has been verified to be economically available for investigation of the dust effect on wind turbine airfoils.
Virtual Prototyping for Modern Internet-of-Things Applications: A Survey

Modern technological industries fused with the Internet-of-Things (IoT) have been advancing rapidly. The joint usage of several technologies has led to the reshaping of the modeling and simulation techniques into the virtualization of physical systems. Thus, the concept of virtual prototyping has emerged as a significant development in distributed IoT applications that includes early exploration, optimization, and security assessments. Several industries have been employing various types of prototyping e.g., virtual platforms, digital twins, and application-specific virtualization techniques, to achieve individual needs for development. In this survey, we clarify some of these concepts and the distinctions between them, provide a comprehensive overview of various prototyping technologies, and discuss how several virtualization technologies play a transformative role in the design and operation of intelligent cyber-physical systems.
A certain class of series associated with the zeta function

The authors apply the theory of the double Gamma function, which was recently revived in the study of the determinants of the Laplacians, in order to give closed-form evaluations of some series involving the Zeta function. Each of these series is evaluated at different arguments from those considered in several earlier works. The possibility of numerical computations of the sums of the series considered here is also indicated.
Transcriptome Sequencing Reveals Salmonella Flagellin Activation of Interferon-β-Related Immune Responses in Macrophages

The flagellin (FliC) of Salmonella typhimurium is a potential vaccine adjuvant as it can activate innate immunity and promote acquired immune responses. Macrophages are an important component of the innate immune system. The mechanism of flagellin’s adjuvant activity has been shown to be related to its ability to activate macrophages. However, few studies have comprehensively investigated the effects of Salmonella flagellin in macrophages using transcriptome sequencing. In this study, RNA-Seq was used to analyze the expression patterns of RAW264.7 macrophages induced by FliC to identify novel transcriptomic signatures in macrophages. A total of 2204 differentially expressed genes were found in the FliC-treated group compared with the control. Gene ontology and KEGG pathway analyses identified the top significantly regulated functional classification and canonical pathways, which were mainly related to immune responses and regulation. Inflammatory cytokines (IL-6, IL-1β, TNF-α, etc.) and chemokines (CXCL2, CXCL10, CCL2, etc.) were highly expressed in RAW264.7 cells following stimulation. Notably, flagellin significantly increased the expression of interferon (IFN)-β. In addition, previously unidentified IFN regulatory factors (IRFs) and IFN-stimulated genes (ISGs) were also significantly upregulated. The results of RNA-Seq were verified, and furthermore, we demonstrated that flagellin increased the expression of IFN-β and IFN-related genes (IRFs and ISGs) in bone marrow-derived dendritic cells and macrophages. These results suggested that Salmonella flagellin can activate IFN-β-related immune responses in macrophages, which provides new insight into the immune mechanisms of flagellin adjuvant.
Fast Calculation of Linear Finite Element Method for the Stationary Fractional Advection Dispersion Equations

Appropriate variational formulation and detailed implementation of linear finite element for the stationary fractional advection dispersion equation(FADE) are discussed. Since fractional derivative is nonlocal operator, the stiffness matrix of finite element on traditional variational formulation for FADE is no longer sparse and the computation becomes costly. In this paper, we establish some fractional order integral and differential formulas for linear interpolation basis functions, and then design a special variational formulation which makes the stiffness matrix possess some good properties, such as quasi-symmetry, quasi-sparseness and strictly diagonally domination. These properties are very important in reducing the computational cost and guaranteeing the stability of finite element equations. Numerical examples demonstrating these properties are presented and the applications in contaminant transport in groundwater flow are given.
Route of Arsenic Exposure Differentially Impacts the Expression of Genes Involved in Gut-Mucosa-Associated Immune Responses and Gastrointestinal Permeability

First-pass metabolism alters arsenic biotransformation and its immunomodulatory activities. This study aims to determine the mRNA expression of intestinal-immunity- and permeability-associated genes, levels of cytokine/chemokines and levels of immunoglobulin isotypes when CD-1 mice were exposed to a single dose of intravenous (IV) sodium arsenite (50 µg/kg body weight (BW)) and to compare these responses to exposure via oral gavage (OG) (50 µg/kg BW). Samples were collected at 1, 4, 24 and 48 h post IV exposure and 24 and 48 h post OG. Sodium arsenite IV exposure led to a transient modulation of mRNA expression and protein levels of immunity-related genes involved in inflammation/apoptotic pathways and production of cytokines/chemokines, whereas it also led to downregulated expression of genes encoding tight junction, focal adhesion, and gap junction proteins, which are responsible for maintaining cell permeability. Oral exposure perturbed fewer cell-permeability-related genes at 24 and 48 h post exposure. At 24 h post exposure, OG decreased IgA and IgG2b levels; however, IV exposure significantly increased IgG2b, IgG3 and IgA in ileal tissue. Earlier, we showed significant downregulation of mRNA expression of genes involved in the immune-related pathways during OG in the intestinal mucosa of the same animals. Cumulatively, these results provide evidence that the exposure route of a xenobiotic can differentially impact the intestinal responses due to the impact of first-pass metabolism.