Miracle-dz/UniFAR-FTUs huggingface dataset:
NON{INVERTED SKEW UPWIND SCHEME FOR NUMERICAL HEAT TRANSFER AND FLUID FLOW SIMULATIONS

This thesis studies advection modeling for heat transfer and fluid flow problems using a new Non–Inverted Skew Upwind Scheme (called NISUS). Variants of the new scheme are formulated and developed with 8-noded hexahedral elements using the Finite Element Method (FEM) and rectangular elements based on a Finite Volume Method (FVM). A new method of mass weighting to predict convective fluxes of each scalar from the nodal point values is developed. Due to an explicit representation in terms of nodal variables, local inversion of the upwind coefficient matrix is not needed. Also, this thesis evaluates two variants of the new scheme (i.e., 3node / 3-point and 4-node / 8-point formulations) within a 3–D FEM and a third variant within a 2–D FVM. The 3–D FEM variants are applied to a variety of test problems involving the transport of a scalar variable, while the 2–D FVM variant is applied to fluid flow problems including natural convection in an enclosure and micro–channel flow simulations. The promising performance of NISUS, as compared with exact and previous solutions, is demonstrated both in terms of accuracy and stability. Furthermore, a new data storage format called Compressed Banded Data (CBD) is developed for sparse banded matrices generated by the control volume finite element method (CVFEM). The platform of the new CBD structure permits dynamic switching between various solvers, without any procedural change in the implementation of existing simulation software. The performance of different Krylov techniques with an ILU(0) preconditioner is observed and compared in three test problems with a direct solver.
Carotid Artery Stenosis: A Look Into the Diagnostic and Management Strategies, and Related Complications

Carotid stenosis (CS) is a buildup of atherosclerotic plaque within the artery leading to a wide range of symptoms, from mild symptoms, including blurred vision and confusion, to much more life-threatening presentations, including paralysis due to stroke. The presentation is insidious, with symptoms exhibiting predominantly at severe stenosis; hence the emphasis is placed on the importance of early diagnosis, treatment, and lifestyle modifications. CS is seen undergoing almost the same pathogenesis of any atherosclerotic plaque formation, from endothelial damage of the artery lumen to the formation of a fibrous cap with a foam cell, lipid-filled core. The findings of our review article were consistent with the recent literature, depicting that comorbid hypertension, diabetes, and chronic kidney disease (CKD), and lifestyle aspects, including smoking and diet, played the most salient role in plaque development. Among several imaging modalities, duplex ultrasound (DUS) imaging is the widely preferred method in clinical practice. Carotid endarterectomy (CEA) and carotid stenting are the primarily advocated procedures for symptomatic severe stenosis, with similar long-term outcomes. Although, earlier clinical trials showed promising results in mitigating the risk of stroke among asymptomatic severe CS with surgical intervention. However, recent advancements have shifted the focus to medical management alone due to comparable results among the asymptomatic population. Both surgical and medical regimens are beneficial in treating patients, but it is still an ongoing debate as to which is predominantly superior. The currently advancing trials and research will help elucidate definitive guidelines. However, the massive impact of lifestyle modifications advocates some degree of individualized multidisciplinary management strategies.
Energy-Optimal Adaptive Control Based on Model Predictive Control

Energy-optimal adaptive cruise control (EACC) is becoming increasingly popular due to its ability to save energy. Considering the negative impacts of system noise on the EACC, an improved modified model predictive control (MPC) is proposed, which combines the Sage-Husaadaptive Kalman filter (SHAKF), the cubature Kalman filter (CKF), and the back-propagation neural network (BPNN). The proposed MPC improves safety and tracking performance while further reducing energy consumption. The final simulation results show that the proposed algorithm has a stronger energy-saving capability compared to previous studies and always maintains an appropriate relative distance and relative speed to the vehicle in front, verifying the effectiveness of the proposed algorithm.
Time-Splitting Errors in the Numerical Integration of Semilinear Systems of Ordinary Differential Equations

In this paper the authors analyze splitting errors in numerical schemes for a semilinear system of ordinary differential equations (ODEs). It is well known that errors occur even when splitting the continuous fully linear system analytically, consequently splitting numerical schemes introduces additional errors. A general approach to delineate and avoid such errors for the above-mentioned class of ODEs is proposed.
Laterally converging duct flows. Part 3. Mean turbulence structure in the viscous layer

In order to provide fundamental bases for incorporating the effects of favourable streamwise pressure gradients into models for internal turbulent flows and turbulent boundary layers, time series measurements with a cross-wire probe and a wall shear stress sensor were obtained simultaneously in an oil channel both for fully developed and laterally converging flows. Data were concentrated in the viscous layer and at the centreplane for slight to highly favourable pressure gradients. (Here the viscous layer is defined as the region where viscous effects are significant, but not necessarily dominant; it includes the ‘laminar’ and buffer sublayers in the terminology of some investigators). Results presented include comparisons of the profiles of the mean statistics, plus correlations and spectra, of streamwise and wall-normal components, their product and the wall shear stress. The key new data are the measurements of the fluctuating normal component and related statistics in the viscous layer for highly favourable pressure gradients. For the outer half of the viscous layer its root-mean-square fluctuations decrease as the pressure gradient is increased, consistent with heretofore unconfirmed predictions from direct numerical simulations. Based on examination of the probability density distributions, one may conclude that an effect of a strong pressure gradient is to reduce transport of momentum in the outer part of the viscous layer.
Convergence for a family of neural network operators in Orlicz spaces

In this paper, we develop the theory for a family of neural network (NN) operators of the Kantorovich type, in the general setting of Orlicz spaces. In particular, a modular convergence theorem is established. In this way, we study the above family of operators in many instances of useful spaces by a unique general approach. The above NN operators provide a constructive approximation process, in which the coefficients, the weights, and the thresholds of the networks needed in order to approximate a given function f, are known. At the end of the paper, several examples of Orlicz spaces, and of sigmoidal activation functions for which the present theory can be applied, are studied in details.
Subgrid-scale dynamics and model test in a turbulent stratified jet with coexistence of stable and unstable stratification

ABSTRACT The subgrid-scale dynamics of stratified flows is studied in a horizontally introduced turbulent jet with coexistence of stable and unstable stratification of a low Richardson number case and a high Richardson number case. The positive production of subgrid-scale kinetic energy and the production of scalar variance suggest the forward energy cascade. The subgrid-scale buoyant destruction plays a role as a sink of subgrid-scale kinetic energy in the stable stratification while holds a role of turbulent generation in the unstable stratification. The role-switch of buoyant destruction in the stable stratification of high-Ri case implies the occurrence of a destabilising process triggered by the coupled instability mechanisms. The energy balance assumption related to the production of and the dissipation of subgrid-scale kinetic energy as well as the subgrid-scale buoyant destruction may fail. The a-priori test suggests the scale-invariant dynamic and standard Smagorinsky models not to work properly here, while the scale-dependent dynamic model gives a decent performance but with restrictions of the ratio between two testing filter scales.
Local two-radii theorems on the multi-dimensional sphere

Consider those functions on the -dimensional sphere that have zero integrals over all geodesic balls with centres in a given set . We obtain a description of such functions in the case when is a geodesic sphere on . We also find a criterion for the existence of non-zero functions with this property in the case when the set of centres is the union of two geodesic spheres. We obtain analogues of these results for quasi-analytic classes of functions.
Filter analysis by use of pencil of functions: Part II

A pair of functions, when linearly combined via a parameter, produces a mathematical entity called a pencil of functions. These pencils are especially interesting when a signal g_{1} (t) is processed by a cascade of simple operators such as first-order filters (FOF's) 1/(s +q_{l}), q_{l} > 0, i = 1,{\cdots}, n, because the pencils formed by pairs of the resulting signal ensemble g_{l} + y_{l}g_{l+1} possess some very useful properties. Most useful of these concerns the linear dependence of the set of pencils thus produced. It is shown in Parts I and II that a necessary condition for a set of pencil of functions to be linearly dependent is a polynomial equation that must be satisfied by their parameters. Applications of the result include linear system identification and rational modeling of the power density spectrum of a random signal. The former of these is discussed in Part I. System dynamics is estimated in closed form requiring no prior estimates. The estimated parameters coincide with true values in the event of noise-free data. Inner products are utilized for computations, and minimum variance corrections are made when the data are noisy.
Alignment-dependent terahertz radiation in two-color photoionization of molecules

The generation of terahertz radiation from an ensemble of aligned air molecules in intense twocolor laser fields has been investigated. Our experiments show that terahertz radiation yields are strongly modulated by the alignment of nitrogen and oxygen molecules. We explain this phenomenon in the context of the plasma current model combined with alignment-dependent ionization, in which nitrogen molecules aligned parallel to the laser field yield more ionization and plasma currents, resulting in enhanced terahertz radiation. Our measurements also provide the ratio of the ensemble-averaged ionization rates of nitrogen molecules aligned parallel versus orthogonal to the laser field.
Additive Divisibility in Compact Topological Semirings

A topological semiring (S, + , ·) is a nonempty Hausdorff space S on which are defined continuous and associative operations, termed addition (+) and multiplication (·), such that the multiplication distributes over addition from left and right. The additive semigroup (S, +) need not be commutative. We prove that the set A of additively divisible elements of a compact semiring S is a two-sided multiplicative ideal, containing the set E[+] of additive idempotents, with the property that (A.S) ∪ (S.A) ⊂ E[+].
Not Your Grandma's Fascism: Fame, Femininity, and Race in Far-Right Postcolonial India and Brazil

Abstract:Much scholarship on the far right focuses on Europe and North America, whereas case studies outside of these regions are often neglected or not recognized as constituting the same phenomenon. In this article, we compare two democracies in the Global South—India and Brazil—to showcase far-right movements within these countries. We situate the "postcolonial neoliberal nationalism" that has shaped the basis of far-right claims in India and Brazil. To illuminate this, we explore female social media influencers within these far-right milieus, and their role in the reproduction of gender, class, and racial hierarchies. Combined with this are insights from media studies on influencer culture as a means of analyzing the performativity of far-right women to advance exclusionary agendas. Overall, we highlight the inherent contradictions and complexity of how far-right female influencers in the Global South are promoting local expressions of gendered indigeneity while also contributing to global far-right narratives.
Experimental Verification and Calculation of Aviation Route Doses

Recent findings in radiation transport calculations and experiments in the Earth's atmosphere are summarised. Emphasis is placed on the neutrons as the major contributor to effective dose and dose equivalent. Spectral distributions and conversion coefficients are used to determine the dose quantities. The conservativity of the operational quantity is studied. The depth dose characteristic in the atmosphere and its slope is compared with data from theoretical calculations. The concept of the computer program package EPCARD is explained in brief which is intended to combine experimental and theoretical data obtained from different laboratories under different geomagnetic and solar conditions.
Believable scales and parameterizations in a spectral transform model

Abstract Through analysis of the spectra of a Dirac delta function the notion of believable and unbelievable scales in a spectral transform model is quantified. The smallest resolved local features are shown to have an average wavenumber a factor of 2 less than that of the truncation, and a half-width 1.6 times greater than that associated with the smallest-scale waves and 2.4 times the maximum grid size of a quadratic transform grid. A reassessment of the philosophy of including parameterizations is introduced, the central point of which is a separation of the parameterization and dynamical truncation scales. The use of spectral filters applied to the input and output from gridpoint physical parameterization schemes and the use of a coarse “physics” grid are proposed. Diagnostics summarizing the noise in a spectral model are introduced, and a moist baroclinic wave life-cycle simulation and a one-dimensional analog to photochemistry at the terminator are discussed to demonstrate their use.
Influence of piezoelectric nonlinearity on active vibration suppression of smart laminated shells using strong field actuation

In this work, we study the effect of piezoelectric nonlinearity on shape and active vibration control of smart piezolaminated composite and sandwich shallow shells under strong field actuation. An efficient finite element model with advanced laminate kinematics and full electromechanical coupling is developed for this purpose. The nonlinearity is modeled using a rotationally invariant quadratic constitutive relationship for the piezoelectric material. For the laminate kinematics, a recently developed efficient layerwise theory, which is computationally as efficient as an equivalent single-layer theory, and has been shown to yield very accurate results in comparison with three-dimensional piezoelasticity based solutions for linear electromechanical response of hybrid laminated shells, has been employed. The nonlinear static response for shape control is obtained using the direct iteration method, and the active vibration control response with linear quadratic Gaussian controller is obtained by using the feedback linearization approach through control input transformation. It is shown that the linear model significantly overestimates the voltage required for shape or vibration control, when the applied electric field is beyond the threshold limit of the actuator. Thus, the use of the nonlinear model is essential for designing the control system utilizing the full actuation authority of the actuators. The effects of actuator thickness, radius of curvature to span ratio and applied loading on the relative difference between linear and nonlinear predictions are illustrated for shape and vibration control of smart cylindrical and spherical shells.
Origin and annealing of deep-level defects in GaNAs grown by metalorganic vapor phase epitaxy

Deep-level defects were investigated by deep level transient spectroscopy on the as-grown and annealed GaNAs layers of various nitrogen (N) contents. The unintentionally doped (uid) GaNAs layers were grown by metalorganic vapor phase epitaxy with N = 1.4%, 2.0%, 2.2%, and 2.4% on GaAs substrate. The possible origin and evolution of the deep-level defects upon annealing were analyzed with the use of the GaNAs band gap diagram concept [Kudrawiec et al., Appl. Phys. Lett. 101, 082109 (2012)], which assumes that the activation energy of donor traps decreases with N-related downward shift of the conduction band. On the basis of this diagram and in comparison with previous results, the N-related traps were associated with (N−As)As or (N−N)As split interstitials. It was also proposed that one of the electron traps and the hole trap, lying at the same level position in the bandgap of the annealed uid-GaNAs layers, can both act as one generation-recombination center partially responsible for poor optical properties of this alloy.
Pressure fluctuations beneath instability wavepackets and turbulent spots in a hypersonic boundary layer

Abstract To investigate the pressure-fluctuation field beneath turbulent spots in a hypersonic boundary layer, a study was conducted on the nozzle wall of the Boeing/AFOSR Mach-6 Quiet Tunnel. Controlled disturbances were created by pulsed-glow perturbations based on the electrical breakdown of air. Under quiet-flow conditions, the nozzle-wall boundary layer remains laminar and grows very thick over the long nozzle length. This allows the development of large disturbances that can be well-resolved with high-frequency pressure transducers. A disturbance first grows into a second-mode instability wavepacket that is concentrated near its own centreline. Weaker disturbances are seen spreading from the centre. The waves grow and become nonlinear before breaking down to turbulence. The breakdown begins in the core of the packets where the wave amplitudes are largest. Second-mode waves are still evident in front of and behind the breakdown point and can be seen propagating in the spanwise direction. The turbulent core grows downstream, resulting in a spot with a classical arrowhead shape. Behind the spot, a low-pressure calmed region develops. However, the spot is not merely a localized patch of turbulence; instability waves remain an integral part. Limited measurements of naturally occurring disturbances show many similar characteristics. From the controlled disturbance measurements, the convection velocity, spanwise spreading angle, and typical pressure-fluctuation field were obtained.
Experimental Investigations of Reconfigurable Porosity for Aerodynamic Control

Experimental results to demonstrate the application of an innovative, low-power, flow control technique – reconfigurable porosity – for aerodynamic control is presented. The control is based on selective actuation and de-actuation of discrete holes that form unique porous-patterns to enable small amounts of mass transfer in-and-out of the surface. Since the technique relies on flow transpiration caused due to natural pressure loading around the aerodynamic surface, power is required only for the control of hole-patterns, and not for plumbing, as in the case of suction or blowing. Low-power, MEMS-based microvalves can be used to form discrete hole-patterns to further minimize the total power consumption. Transpiration of air at certain optimal locations on the aerodynamic surface is hypothesized to energize the boundary layer, forcing a delay in flow separation. Controlled threedimensional perturbations caused by patterned-porosity can be rapidly re-configured to adapt to the changing flow conditions so as to continually operate in an optimal configuration for improved effectiveness. To assess the control performance, low-speed experiments are conducted on two aerodynamic models, a multi-wedged supersonic wing model and a complete projectile model (with two four fins arranged in cruciform (+) configuration). Force data as well as flow visualization results are presented to illustrate the patterned-porosity concept. Quantitative results show that control forces of varying magnitude can be generated using different porous patterns for a range of alpha conditions. This control technique has demonstrated the ability to generate adequate levels of control forces for course correction and maneuvering of air vehicles.
The infinitely-many-neutral-alleles diffusion model

A diffusion process X(·) in the infinite-dimensional ordered simplex is characterized in terms of the generator defined on an appropriate domain. It is shown that X(·) is the limit in distribution of several sequences of discrete stochastic models of the infinitely-many-neutral-alleles type. It is further shown that X(·) has a unique stationary distribution and is reversible and ergodic. Kingman's limit theorem for the descending order statistics of the symmetric Dirichlet distribution is obtained as a corollary.
Quantized linear quadratic Gaussian control for scalar systems

This chapter considers the quantized linear quadratic Gaussian (QLQG) control problem, which is generalized from the classical LQG problem but with the constraint that the feedback signal is quantized by a fixed-rate quantizer. It turns out that the well-known separation principle for LQG control fails to generalize to QLQG, and this is caused by the fact that minimizing the quantization error at each time instant separately does not lead to a minimum cost globally. Here we consider the QLQG problem for a scalar system and present an adaptive quantization scheme. Using this scheme, we show that the quantization distortion order is R2-2R for a large bit rate R. This means that the separation principle holds approximately when the bit rate is sufficient. More importantly, this adaptive quantization scheme guarantees mean-square stability for the closed-loop system.
Numerical Simulation of Mesoscale Circulation in Taiwan and Surrounding Area

Abstract Mesoscale circulation around Taiwan and the surrounding area has been investigated using the Purdue mesoscale model. The numerical results generated in an inviscid atmosphere show: (a) A cyclonic vortex forms in the southeast and a slightly weaker anticyclonic vortex forms in the northeast of Taiwan uner a westerly or southwesterly wind. Subsidence warming also generates a relative low pressure on the southeastern coast. (b) A low pressure associated with a cyclonic flow forms in the northwest and a slightly weaker anticyclonic flow forms in the southwest of Taiwan under an easterly mean flow. The easterly wind tends to turn northeasterly over the Taiwan Strait, with a stronger wind speed, due to the blocking effects of the mountains in Taiwan and along the Chinese coast. (c) Under the existence of an easterly surface wind with a reverse shear, the horizontal temperature advection is not important in the formation of low pressure on the leeside, due to the small length scale of the island of Taiw.