Miracle-dz/UniFAR-FTUs huggingface dataset:
On steady laminar flow with closed streamlines at large Reynolds number

Frictionless flows with finite voticity are usually made determinate by the imposition of boundary conditions specifying the distribution of vorticity ‘at infinity’. No such boundary conditions are available in the case of flows with closed streamlines, and the velocity distributions in regions where viscous forces are small (the Reynolds number of the flow being assumed large) cannot be made determinate by considerations of the fluid as inviscid. It is shown that if the motion is to be exactly steady there is an integral condition, arising from the existence of viscous forces, which must be satisfied by the vorticity distribution no matter how small the viscosity may be. This condition states that the contribution from viscous forces to the rate of change of circulation round any streamline must be identically zero. (In cases in which the vortex lines are also closed, there is a similar condition concerning the circulation round vortex lines.) The inviscid flow equations are then combined with this integral condition in cases for which typical streamlines lie entirely in the region of small viscous forces. In two-dimensional closed flows, the vorticity is found to be uniform in a connected region of small viscous forces, with a value which remains to be determined—as is done explicitly in one simple case—by the condition that the viscous boundary layer surrounding this region must also be in steady motion. Analogous results are obtained for rotationally symmetric flows without azimuthal swirl, and for a certain class of flows with swirl having no interior boundary to the streamlines in an axial plane, the latter case requiring use of the fact that the vortex lines are also closed. In all these cases, the results are such that the Bernoulli constant, or ‘total head’, varies linearly with the appropriate stream function, and the effect of viscosity on the rate of change of vorticity at any point vanishes identically.
Diagonal Equations Over Large Finite Fields

We consider polynomials of the form with non-zero coefficients ai in a finite field F. For any finite extension field K ⊇ F, let fk :Kn → K be the mapping defined by f. We say f is universal over K if fK is surjective, and f is isotropic over K if fK has a non-trivial “kernel“; the latter means fK(X) = 0 for some 0 ≠ x ∊ Kn . We show (Theorem 1) that f is universal over K provided |K| (the cardinality of K) is larger than a certain explicit bound given in terms of the exponents d 1,…, dn . The analogous fact for isotropy is Theorem 2. It should be noted that in studying diagonal equations we fix both the number of variables n and the exponents di , and ask how large the field must be to guarantee a solution.
The role of H3+in planetary atmospheres

Spectroscopic studies of the upper atmospheres of the giant planets using infrared wavelengths sensitive to the H3+ molecular ion show that this species plays a critical role in determining the physical conditions there. For Jupiter, we propose that the recently detected H3+ electrojet holds the key to the mechanism by which the equatorial plasma sheet is kept in (partial) co–rotation with the planet, and that this mechanism also provides a previously unconsidered source of energy that helps explain why the jovian thermosphere is considerably hotter than expected. For Saturn, we show that the H3+ auroral emission is ca. 1% of that of Jupiter because of the lower ionospheric/thermospheric temperature and the lower flux of ionizing particles precipitated there; it is probably unnecessary to invoke additional chemistry in the auroral/polar regions. For Uranus, we report further evidence that its emission intensity is controlled by the cycle of solar activity. And we propose that H3+ emission may just be detectable using current technology from some of the giant extra–solar planets that have been detected orbiting nearby stars, such as Tau Bootes.
A quantitative test case for global‐scale dynamical cores based on analytic wave solutions of the shallow‐water equations

Recently derived analytic wave solutions of the shallow‐water equations (SWEs) on the rotating spherical Earth are employed to construct a test case for hydrostatic dynamical cores of global‐scale general circulation models (GCMs). The proposed test case is more relevant to the SWEs than the frequently used Rossby–Haurwitz test case which is based on wave solutions of the non‐divergent barotropic vorticity equation and not the SWEs. The applicability of the proposed test case to operational GCMs is demonstrated by using the spectral Eulerian dynamical core of the atmospheric component of NCAR's Community Earth System Model to simulate the analytic solutions. An initial slowly propagating Rossby wave and a fast eastward propagating inertia–gravity wave are both accurately simulated for 100 wave periods. In order to quantify the accuracy of the simulations, two error‐measures are suggested which complement the conservation of global energy and, unlike the frequently used L2 error‐measure, provide independent assessments of the errors in the phase speeds and the meridional structures of the simulated waves and are therefore more relevant to periodic wave solutions.
A COLORFUL DETERMINANTAL IDENTITY, A CONJECTURE OF ROTA, AND LATIN SQUARES

the polynomial x2 + x + d is prime for all integers x with 0 < x < d 2. One final comment: If D is an almost Euclidean subring of a number field, Theorem 2 tells us that we may use the absolute value of the norm as a near Euclidean function. Suppose that D is actually Euclidean. Will the absolute value of the norm serve as a Euclidean function? It is interesting to note that Hardy and Wright [4, p. 212] define a Euclidean domain not in the usual way but explicitly using the norm as the Euclidean function. However, the answer to the question is that the norm may not work. In fact, it was shown in [3] that Z[;], with; = (1 + )/2 is an example of a ring which is Euclidean, but not with respect to the absolute value of the norm.
New Hybrid Differential Evolution and Particle Swarm Optimization Algorithm and Its Application

In order to solve the problem that the B2 C electronic commerce logistics distribution optimization accuracy is not high,a new hybrid differential evolution and particle swarm optimization heuristic optimization algorithm based B2 C e-commerce logistics distribution optimization was proposed.Firstly,the particle swarm population was used as auxiliary mutation operator to do the crossover operation with differential evolution algorithm population,resulting new generation that inherits the advantages of characteristics of parents,thus avoiding the single algorithm premature convergence and low convergence rate.Through simulation comparison with the other existing improved algorithm,the algorithm here can effectively escape from local minima,prevent premature convergence,and the convergence is fastest.The simulation showed the designed distribution scheme has the faster calculation speed and better convergence of the target value.
Synchronisation of the equatorial QBO by the annual cycle in tropical upwelling in a warming climate

The response of the period of the quasi‐biennial oscillation (QBO) to increases in tropical upwelling are considered using a one‐dimensional model. We find that the imposition of the annual cycle in tropical upwelling creates substantial variability in the period of the QBO. The annual cycle creates synchronisation regions in the wave forcing space, within which the QBO period locks onto an integer multiple of the annual forcing period. Outside of these regions, the QBO period undergoes discrete jumps as it attempts to find a stable relationship with the oscillator forcing. The resulting set of QBO periods can be either discrete or broad‐banded, depending on the intrinsic period of the QBO.
Length-scale-dependent stress relief mechanisms in indium at high homologous temperatures

Nanoindentation and electron microscopy have been used to examine the length-scale-dependent stress relaxation mechanisms in well-annealed, high-purity indium at a homologous temperature of 0.69. The experimental methods, analysis, and observations serve as a stepping stone in identifying the stress relaxation mechanisms enabling the formation and growth of metallic dendrites originating at the buried interface between a metallic anode and a solid electrolyte separator. Indium’s load–displacement data are found to be very similar to that of high-purity lithium. Residual hardness impressions show two distinct surface morphologies. Based on these morphologies, the measured hardness, and the estimated pile-up volume, it is proposed that residual impressions exhibiting significant pile-up are the result of deformation dominated by interface diffusion. Alternatively, impressions with no significant pile-up are taken to be the result of shear-driven dislocation glide. An analytical model is presented to rationalize the pile-up profile using interface diffusion.
The Pickup And Delivery Problem With Time Windows And Transshipment

Abstract Pickup and delivery problems with time windows are frequently encounlcred by courier companies. These companies serve customers that require transporiation of a package from a pickup location to a delivery location. This paper presents an empirical study on usefulness of transshipment points in such a conlexl. Transshipnicnl allows for a request to be served by Iwo vehicles: one vehicle collects the load at the pickup location, drops it al a transshipment point, and another vehicle carries the load lo the delivery location. The motivation for this work came from the practice observed in a large San Francisco based courier company that allows transshipment of loads between vehicles. The company serves large geographic area covering several neighboring cities. The main reasoning behind allowing transshipment lies in the idea of keeping drivers in their home area. We have investigated a generalization of ihis transshipment practice, allowing vehicles to move through entire service area in order to evaluate the usefulness of transshipment. We identify circumstances under which transshipment may be beneficial.
Coupling the INDRA and VAMOS multi-detectors for symmetry energy studies

The study of the symmetry energy under well controlled laboratory conditions serves to provide constraints for theoretical models covering a wide range of physical phenomena, from the neutron skin thickness of 208Pb to the structure and dynamics of neutron stars. Of particular interest at the present time is the density dependence of the symmetry energy. The INDRA-VAMOS (E503) experiment intends to extract constraints on the density dependence of the symmetry energy at low densities using isotopic scaling and isospin diffusion measurements. In this report the physics motivation and experiment will be discussed in detail, as well as the calibration of the detectors and recent changes to the analysis code.
THE EFFECT OF WING TIP BLOWING ON THE VORTEX DRAG

Experimental work has been conducted to evaluate the effect of wing tip blowing on the vortex drag of a rectangular low aspect wing at low speed. A novel tip blowing system is presented which consist of three Coanda type jets. The jets can be vectored to produce a better tip vortex attenuation. Wind tunnel tests were performed for measurements of Lift, Drag and Pitching moment for a large number of combinations of jet vertical angles and position. The tests were conducted at constant Reynolds number for incidence angles from –4 to 22 degrees. Results indicated an increase in Lift and pitching moment with an inherent decrease in drag for most of the configuration tested
A Simple Method for Estimating the Latent Heat Flux over Grass from Radiative Bowen Ratio

Abstract The evaluation of crop evapotranspiration from infrared temperature is usually calculated as the residual component of the surface energy balance. This method has given good results over a full grass canopy cover with unstressed transpiration, in spite of the not well understood meaning of the aerodynamic resistance needed. A simple and more accurate method, which determines the Bowen ratio (β) and the latent heat flux (λE) over a reference grass area without knowledge of surface resistances, is proposed. The proportionality between β and a radiative Bowen ratio βs is shown. The radiative Bowen ratio is derived from surface and air temperatures and vapor pressure. This relationship allows the estimation of λE from temperatures, vapor pressure, and solar radiation measurements at one reference level. The new method gives an estimated error of around 10% in front of the residual one, where the wind speed has to be known, with an error of above 20%. The proposed method requires further verification .
FIXED POINT THEOREM ON PARTIAL METRIC SPACES INVOLVING RATIONAL EXPRESSIONS

We establish a fixed point theorem involving a rational expression in a complete partial metric space. Our result generalizes a well-known result in (usual) metric spaces. Also, we introduce an example to illustrate the usability of our result. 2000 Mathematics Subject Classification: 47H10; 54H25; 46J10; 46J15
Towards fast and accurate cardiac magnetic resonance flow quantification

In general, high spatial and temporal resolutions in cine cardiac imaging require long scan times making breath-hold acquisition impossible in many cases. To enable free-breathing cardiac imaging, methods such as naviga¬ tor gating were developed to reduce image artifacts due to respiratory motion. Nevertheless, residual image blurring is seen in images acquired late in the cardiac cycle. Image blurring itself hampers accurate blood flow quantification especially in vessels exhibiting high flows during dias¬ tole. In the present work, the navigator gating and slice tracking method was extended by using navigator information to correct for in-slice motion components throughout the cardiac cycle. For this purpose, a standard 2D cine phase contrast sequence with navigator gating and slice position correction was used and navigator information was recorded along with the raw k-space data. In post-processing, in-plane motion components arising from respiration during the actual data acquisition were estimated and corrected according to the Fourier shift theorem. In phantom exper¬ iments, the performance of the correction algorithm for different slice an¬ gulations with respect to the navigator orientation was validated. In vivo, coronary flow measurements were performed in nine healthy volunteers. The correction algorithm led to considerably improved vessel sharpness throughout the cardiac cycle in all measured subjects (increase in ves¬ sel sharpness: 16±11% (mean±SD)). Furthermore, these improvements resulted in increased volume flow rates (16±13% (mean±SD)) after retro¬ spective correction indicating the impact of the method. It is concluded that retrospective respiratory motion corrections for navigated cine 2D velocity mapping can correct for in-plane motion components, providing better image quality for phases acquired late in the cardiac cycle. There¬ fore, this method holds promise in particular for free-breathing coronary flow quantification.
Generalized Gradients, Lipschitz behavior and Directional Derivatives

In the study of optimization problems it is necessary to consider functions that are not differentiable. This has led to the consideration of generalized gradients and a corresponding calculus for certain classes of functions. Rockafellar [16] and others have developed a very strong and elegant theory of subgradients for convex functions. This convex theory gives point-wise criteria for the existence of extrema in optimization problems. There are however many optimization problems that involve functions which are neither differentiable nor convex. Such functions arise in many settings including optimal value functions [15]. In order to deal with such problems Clarke [3] defined a type of subgradient for nonconvex functions. This definition was initially for Lipschitz functions on R”. Clarke extended this definition to include lower semicontinuous (l.s.c.) functions on Banach spaces through the use of a directional derivative, the distance function from a closed set and tangent and normal cones to closed sets.
A Study of an Oregon Sea Breeze Event

Abstract A series of meteorological observations including aircraft, pilot balloon (pibal), rawinsonde, surface buoy, and special land-based surface observations was taken on 23–24 August 1972, on the central Oregon coast, to investigate the mesoscale thermal and kinematic responses of the lowest 4 km of the atmosphere during a sea breeze event. A description of those field observations is given. Vertical cross sections of the wind field on a line perpendicular to the coast, extending 60 km inland from data obtained at three pibal stations, are presented and discussed. Time sections of the wind field and temperature fields at the coast are discussed. Mesoscale features are presented and related to prevailing synoptic-scale changes occurring aloft during the observational period. The sea breeze event on 23 August exhibited the following important characteristics: 1) a sea breeze front, distinguishable in the zonal wind field, which penetrated more than 60 km inland; 2) a distinct wind maximum which followe.
A study of resolvent set for a class of band operators with matrix elements

Abstract For operators generated by a certain class of infinite three-diagonal matrices with matrix elements we establish a characterization of the resolvent set in terms of polynomial solutions of the underlying second order finite-difference equations. This enables us to describe some asymptotic behavior of the corresponding systems of vector orthogonal polynomials on the resolvent set. We also find that the operators generated by infinite Jacobi matrices have the largest resolvent set in this class.
A Sinc-Galerkin Approximate Solution of the Reaction-Diffusion Process in an Immobilized Biocatalyst Pellet

In recent years, an increasing interest has focused on the use of Sinc methods as an essential tools for solving some singular problems arising in different areas of applied sciences. Due to the presence of singularity, these problem sr aise di fficulties in obtaining their analytic or numerical solutions, and various schemes have been proposed to overcome these difficulties. However, among existing approaches, the Sinc methods are well-suited for handling singularity and have high performance on boundary value problems (BVPs) such as problems on unbounded domains or problems with endpoint singularities. In this work, in several geometries and kinetics, an implementation of the Sinc–Galerkin scheme is used to approximate effectiveness factor and concentration profile of key component when a single independent reaction takes place in a porous catalyst structure where enzymes are immobilized. A comparison between the proposed approximated solution and numerical solution reveals that the Sinc–Galerkin method (SGM), as demonstrated with examples, is reliable, accurate and its convergence rate is high.
How the melanin concentration in the skin affects the fluorescence-spectroscopy signal formation

The influence of various melanin concentrations on the endogenous fluorescence intensity of biological tissue has been experimentally studied, and the fluorescence signals have been modeled by the Monte Carlo method. The modeling is based on a four-layer optical model of the skin, using known optical parameters of skin with various melanin concentrations. The fluorescence spectra obtained by the Monte Carlo method agrees with the results of the experimental investigations.
Single point incremental forming simulation with adaptive remeshing technique using solid-shell elements

Purpose – Numerical simulation of the single point incremental forming (SPIF) processes can be very demanding and time consuming due to the constantly changing contact conditions between the tool and the sheet surface, as well as the nonlinear material behaviour combined with non-monotonic strain paths. The purpose of this paper is to propose an adaptive remeshing technique implemented in the in-house implicit finite element code LAGAMINE, to reduce the simulation time. This remeshing technique automatically refines only a portion of the sheet mesh in vicinity of the tool, therefore following the tool motion. As a result, refined meshes are avoided and consequently the total CPU time can be drastically reduced. Design/methodology/approach – SPIF is a dieless manufacturing process in which a sheet is deformed by using a tool with a spherical tip. This dieless feature makes the process appropriate for rapid-prototyping and allows for an innovative possibility to reduce overall costs for small batches, since.
Understanding COVID-19 Vaccine Uptake and Hesitancy Among People With HIV in Freetown, Sierra Leone: A Cross-sectional Study

Objectives: People living with HIV (PWH) are at increased risk of COVID-19-related morbidity and mortality, yet less is known about COVID-19 vaccination uptake and hesitancy, especially in sub-Saharan Africa. We aimed to evaluate COVID-19 vaccine uptake and hesitancy among PWH in Sierra Leone. Methods: We conducted a cross-sectional study in a convenience sample of PWH in routine care at Connaught Hospital in Freetown, Sierra Leone from April through June 2022. We collected sociodemographic and health-related data. We used the VAX Scale, a validated instrument to assess attitudes towards COVID-19 vaccination. From the responses, we constructed hesitancy (VAX) scores, with higher scores implying negative attitudes toward vaccination. We used generalized linear models to identify factors associated with vaccine hesitancy. Results: A total of 490 PWH were enrolled (71.4% female, median age 38 years, median CD4 count 412 cells/mm3, 83.9% virologically suppressed). About 17.3% had received at least one dose of a COVID-19 vaccine. The mean VAX score was 43.14 {+/-} 7.05, corresponding to 59.9% of participants classified as vaccine-hesitant. Preference for natural immunity (65.8%) and concerns about commercial profiteering (64.4%) were the commonest reasons for hesitancy, followed by mistrust of vaccine benefits (61.4%) and worries about future side effects (48.0%). In adjusted regression analysis, being Muslim ({beta} = 2.563, p < 0.001) and residence in urban areas ({beta} = 1.709, p = 0.010) were associated with greater vaccine hesitancy, while having tested ever for COVID-19 was associated with lesser vaccine hesitancy ({beta} = -3.417, p = 0.027). Conclusion: We observed a low COVID-19 vaccine uptake and high hesitancy among PWH in Sierra Leone. Our findings underscore the need to address vaccine hesitancy as a critical element of efforts to boost COVID-19 vaccine uptake among this population in Sierra Leone.