Miracle-dz/UniFAR-FTUs huggingface dataset:
Development of Smoothed Particle Hydrodynamics for Flow in Complex Geometries and Application of Open Source Software for the Simulation of Turbulent Flow

Turbulence modelling is a key issue in many industrial application, as the computational power of direct numerical simulation (DNS) is insufficient to deal with complex flow structures with high Reynolds number. Also in Industrial applications often involve turbulent flow in complex geometries. Thus developing a computational method which can deal with complex fluid structure, simulate complex geometers that change topology is particular challenging as the connectivity of the computational domain may change dynamically, and still efficient is important. In this thesis we are presenting a remeshed particle-mesh method, the method involves three-dimensional compressible turbulent flow modelling, and coupled with an immersed boundary technique to deal with the complex solid obstacles. This dissertation is composed of three parts. In combustion engines the scavenging process in two-stroke marine diesel engines removes combustion gases from the engine cylinder and fills up the cylinder with the fresh air charge for the next cycle. Understanding the scavenging flow is crucial for the development of such engines, since it affects fuel consumption, engine cooling and production of pollutants. We consider a state-of-the art eulerian methods to study the turbulent flow in a model diesel engine. the goals of this study include validation of large eddy simulations (LES) turbulence models. We study the effect of piston position on the in-cylinder swirling flow in a simplified model of a large two-stroke marine diesel engine. To be able to simulate
Exact imposition of essential boundary condition and material interface continuity in Galerkin‐based meshless methods

Represented by the element free Galerkin method, the meshless methods based on the Galerkin variational procedure have made great progress in both research and application. Nevertheless, their shape functions free of the Kronecker delta property present great troubles in enforcing the essential boundary condition and the material continuity condition. The procedures based on the relaxed variational formulations, such as the Lagrange multiplier‐based methods and the penalty method, strongly depend on the problem in study, the interpolation scheme, or the artificial parameters. Some techniques for this issue developed for a particular method are hard to extend to other meshless methods. Under the framework of partition of unity and strict Galerkin variational formulation, this study, taking Poisson's boundary value problem for instance, proposes a unified way to treat exactly both the material interface and the nonhomogeneous essential boundary as in the finite element analysis, which is fit for any partition of unity‐based meshless methods. The solution of several typical examples suggests that compared with the Lagrange multiplier method and the penalty method, the proposed method can be always used safely to yield satisfactory results. Copyright © 2016 John Wiley & Sons, Ltd.
Molecular dynamics study of flow past an obstacle in strongly coupled Yukawa liquids

Turbulence is one of the outstanding open problems. Fluid flow past an obstacle is simplest of all paradigms to understand the transition to turbulence. For Navier-Stokes liquids, a transition to turbulence is fully governed by Reynolds number (Re). Using classical molecular dynamics simulation of particles interacting via a Yukawa-type interaction, it is demonstrated unequivocally that for a given Re, the transition from laminar to turbulent flow is controlled by strength and range of inter-particle potential. For a wide range of inter-particle interaction strengths and ranges, our simulation data are seen to collapse onto a universal Strouhal-Reynolds curve with new asymptotic values for a range of Re, 2 ≤ Re ≤ 35. From the emergence of vortex street structures behind the obstacle, it is evident that the onset of turbulence is possible at low Re in Yukawa liquids. Growth rates of the instability are obtained using atomistic calculations and are observed to increase quadratically with low values of Re.
X-ray attenuation techniques to explore the dynamics of water in porous media

The flow of water in an unsaturated porous medium is described by Richards' equation. It is based on the assumption that the air in the pores is arbitrarily mobile and able to disappear from the pore space at any time. To solve Richards' equation a parameterization of the relationship between the water content and the matric potential is necessary: the soil-water characteristic. There are several models that describe this curve. Their parameters are typically determined from dynamic outflow experiments. A experimental setup was designed, that allows measurements of X-ray attenuation data and tomographic images during the outflow experiment. With this setup experiments were done to test the validity of Richards' equation for different boundary conditions. Therefore, the measured vertical distribution of water was compared with simulated distributions. The differences found show that the continuity of the air phase is not given at all points, and heterogeneity may prevent the determined effective parameters from being objective. Additionally, methods are introduced to analyze the rough internal structure of samples using X-ray computed tomography.
Smart grid scheduling and control based on master–slave game

ABSTRACT Electric power dispatch is an effective management method used to ensure the safe and stable operation of the power grid, however, there will be some conflicts of interest between the power selling company and the power generation company during the dispatch process. This article aims to minimize the cost of electricity purchased by the power grid company and maximize the sales revenue of power generating company. In this paper, the decision-making space is based on the set of strategies for each power plant output and the on-grid price, proposing a master–slave game scheduling model in which the power grid company is used as the main game and power plants are the game followers. By using the cuckoo algorithm to optimize the master–slave game model, scheduling test results show that master–slave game scheduling provides better overall performance than economic dispatch.
Model Predictive Control of Wind Energy Conversion Systems

The authors provide a comprehensive analysis on the model predictive control of power converters employed in a wide variety of variable-speed wind energy conversion systems (WECS). The contents of this book includes an overview of wind energy system configurations, power converters for variable-speed WECS, digital control techniques, MPC, modeling of power converters and wind generators for MPC design. Other topics include the mapping of continuous-time models to discrete-time models by various exact, approximate, and quasi-exact discretization methods, modeling and control of wind turbine grid-side two-level and multilevel voltage source converters. The authors also focus on the MPC of several power converter configurations for full variable-speed permanent magnet synchronous generator based WECS, squirrel-cage induction generator based WECS, and semi-variable-speed doubly fed induction generator based WECS. Furthermore, this book:
Mathematical Model for Electric Field Sensor Based on Whispering Gallery Modes Using Navier’s Equation for Linear Elasticity

This paper presents and verifies the mathematical model of an electric field senor based on the whispering gallery mode (WGM). The sensing element is a dielectric microsphere, where the light is used to tune the optical modes of the microsphere. The light undergoes total internal reflection along the circumference of the sphere; then it experiences optical resonance. The WGM are monitored as sharp dips on the transmission spectrum. These modes are very sensitive to morphology changes of the sphere, such that, for every minute change in the sphere’s morphology, a shift in the transmission spectrum will happen and that is known as WGM shifts. Due to the electrostriction effect, the applied electric field will induce forces acting on the surface of the dielectric sphere. In turn, these forces will deform the sphere causing shifts in its WGM spectrum. The applied electric field can be obtained by calculating these shifts. Navier’s equation for linear elasticity is used to model the deformation of the sphere to find the WGM shift. The finite element numerical studies are performed to verify the introduced model and to study the behavior of the sensor at different values of microspheres’ Young’s modulus and dielectric constant. Furthermore, the sensitivity and resolution of the developed WGM electric filed sensor model will be presented in this paper.
Transformations to symmetry in the transform-both-sides regression model

The Transform-Both-Sides (TBS) regression model of Carroll and Ruppert (1984) is practical when there exists a conjectured relationship between the dependent variable and the independent variables, although the exact way in which randomness affects the relationship is unknown. The object is to make prediction more precise while respecting the pre-specified relationship. This dissertation is concerned with estimation methods which are alternate to the normal-theory Maximum Likelihood Estimate (MLE) , and whose properties rely solely on symmetry of errors. First, consistency and asymptotic normality of the skewness estimator proposed by Ruppert and Aldershof (1989) are proved. For consistency, an asymptotically eqUivalent estimator is constructed in order to attain convergence. Secondly, a new estimator is proposed based on the notion of a weighted Minimum Distance (MD). This estimate is seen to be a special case of Generalized M-Estimation, a general class for which consistency and asymptotic normality are then proved. The MD estimate is shown to be consistent for Box-COx modified power transformations, and modified power transformations with shift with the power fixed. Some examples are provided which tend to show that the original parameterization in a shifted power transformation is inappropriate. Finally, different features are explored for MD in a simulation study. For a power transformation parameter and normal errors, a weight which appears sui table is produced. Comparisons of MD wi th other estimators in TBS are also provided; in particular, it is found that the loss of efficiency with respect to the MLE in the normal case is not extreme.
Estimation of Ambient Turbulence Intensity over Complex Terrain

The aim of the present study is to develop and validate a framework that can handle with ambient ﬂow modeling of operational wind farms over complex terrain. The developed framework estimates the ambient turbulence intensities, which aﬀect the fatigue loads, energy yields and machinery failures, with respect to several incoming ﬂow parameters such as ambient wind speed, altitude and slope angle. Model has been validated with ambient normal turbulence intensities of IEC-61400 standards and reference speed-up models for representative incoming ﬂow conditions, terrain slope angle and altitude based on two wind turbines in the same row that are in the wake of each other for two speciﬁc wind direction. The comparison shows fair agreement with the modeled ambient turbulence intensities.
Computational materials chemistry for carbon capture using porous materials

Control over carbon dioxide (CO2) release is extremely important to decrease its hazardous effects on the environment such as global warming, ocean acidification, etc. For CO2 capture and storage at industrial point sources, nanoporous materials offer an energetically viable and economically feasible approach compared to chemisorption in amines. There is a growing need to design and synthesize new nanoporous materials with enhanced capability for carbon capture. Computational materials chemistry offers tools to screen and design cost-effective materials for CO2 separation and storage, and it is less time consuming compared to trial and error experimental synthesis. It also provides a guide to synthesize new materials with better properties for real world applications. In this review, we briefly highlight the various carbon capture technologies and the need of computational materials design for carbon capture. This review discusses the commonly used computational chemistry-based simulation methods for structural characterization and prediction of thermodynamic properties of adsorbed gases in porous materials. Finally, simulation studies reported on various potential porous materials, such as zeolites, porous carbon, metal organic frameworks (MOFs) and covalent organic frameworks (COFs), for CO2 capture are discussed.
A Possible Progenitor of the Interstellar Sulfide Bond: Rovibrational Characterization of the Hydrogen Disulfide Cation HSSH+

S2H (HSS) has been observed very recently in the interstellar medium, specifically in the Horsehead nebula. The protonated form, S2H2+, is believed to be a necessary intermediate in its creation in the gas phase in UV-irradiated regions. However, little is known about this radical cation. This work showcases that the trans-HSSH+ isomer is 0.12 eV lower in energy than the cis with a 1.05 eV upper limit to the torsional rotation barrier. Additionally, the vibrational frequencies and rotational constants for both structures are provided in full here for the first time. The cis isomer is likely the more detectable since it possesses a permanent dipole moment and has a high-intensity vibrational frequency for the antisymmetric H−S−S bend at 926 cm−1 (10.8 μm), in the heart of the mid-IR spectral range. A third isomer, H2S−S+ is also reported herein lying ∼0.9 eV in energy above trans-HSSH+. This isomer could play a role in the formation of S2H since it would be kinetically favored in the reaction of sulfur cations with hydrogen sulfide. Further assessment of this third, higher-energy isomer is left for future work.
Non-Abelian Quantum Codes

Like their classical counterparts, quantum codes are designed to protect quantum information from noise. From the perspective of information theory one considers the operations required to restore the encoded information given a syndrome which diagnoses the noise. From a more physics perspective, one considers systems whose energetically protected groundspace encodes the information. In this work we show that standard error correction procedures can be applied to systems where the noise appears as nonabelian Fibonacci anyons. In the case of a Hamiltonian with non-commuting terms, we build a theory describing the spectrum of these models, with particular focus on the 3D gauge color code model. Numerics support the conjecture that this model is gapped, which one would expect for a self-correcting quantum memory. Statement of Authorship Attribution Chapter 3 of this thesis is available as preprint [28], of which I am the sole author. Chapter 4 is based on collaborative work, available as preprint [29]. The algorithm used was co-designed with the co-authors. I implemented, tested and ran the algorithms.
Dual-phase-shift schemes for internal-reflection noise reduction in a Fizeau interferometer

A method to reduce the phase measurement errors generated from internal-reflection light noise in a Fizeau interferometer is proposed. In addition to an ordinary phase-shift by a mechanical translation of the reference surface, the test surface is also mechanically translated between each phase measurement to further modulate the signal phase. For spherical tests, a mechanical phase-shift generally generates a spatial non-uniformity in the phase increment across the observing aperture. It is shown that a minimum of three positional measurements is necessary to cancel out the systematic error caused by this non-uniformity. Linear combinations of the three measured phases can also cancel the additional primary spherical aberrations that occur when the test surface is out of the null position of the confocal configuration.
A Uniform Framework for Timed Automata and Beyond

Timed automata, and machines alike, currently lack a general mathematical characterisation. This work introduces a uniform understanding of these devices that encompasses known behavioural equivalences such as timed bisimulations and timed language equivalences as well as their weak and time-abstract counterparts. All these notions of equivalence between systems are naturally organised in expressiveness spectra based on their discriminating power; these spectra are shown to be independent from any particular computational effect expressed by the systems under scrutiny. As an application, timed automata and their quantitative extensions such as probabilistic ones are studied.
The study of chaotic and regular regimes of the fractal oscillators FitzHugh-Nagumo

In this paper we study the conditions for the existence of chaotic and regular oscillatory regimes of the hereditary oscillator FitzHugh-Nagumo (FHN), a mathematical model for the propagation of a nerve impulse in a membrane. To achieve this goal, using the non-local explicit finite-difference scheme and Wolf’s algorithm with the Gram-Schmidt orthogonalization procedure and the spectra of the maximum Lyapunov exponents were also constructed depending on the values of the control parameters of the model of the FHN. The results of the calculations showed that there are spectra of maximum Lyapunov exponents both with positive values and with negative values. The results of the calculations were also confirmed with the help of oscillograms and phase trajectories, which indicates the possibility of the existence of both chaotic attractors and limit cycles.
Microwaves in Organic and Organometallic Synthesis

This study shows that chemical reactions in polar solvents can be carried out rapidly and conveniently using microwave heating in sealed Teflon containers. Reactions of organic and or ganometallic compounds are reported, and rate enhancements of up to 1,240 times have been observed. The acceleration of reactions (compared to normal reflux conditions)oc curs because the increased pressure developed in the reaction vessels causes superheating of the solvent. The rate of absorption of microwave radiation is affected by the polarity and the volume of the reaction mixture. The heating rate is also influenced by the presence of ions in solution.The yields of relatively slow reactions can be increased by programming the power levels of the microwave oven. This technique allows the reactions to be carried out more safely and to be scaled up to some extent. Microwave heating results in considerable energy savings compared with conventional heating methods. The energy efficiency can be further increased by power pr.
Spatiotemporal auto‐regressive model for origin–destination air passenger flows

The growth of the global airline network has increased the importance of modelling origin–destination air passenger flows for better operational planning and scheduling. Origin–destination air passenger flows are correlated both spatially and temporally because of spatial and temporal relationships of human behaviours and environments. However, most existing studies for modelling air passenger flows have assumed that these relationships are independent; few studies have considered either spatial or temporal dependences. To consider both, we develop a spatiotemporal auto‐regressive model for monthly origin–destination air passenger flows. Benefitting from the special structure of a spatiotemporal dependence matrix, the model proposed can be extended to incorporate multi‐dimensional auto‐regressive coefficients for more flexible modelling. Its application to a real open access aviation data set demonstrates the effectiveness of the proposed model in forecasting monthly air passenger flows.
Experimental Study on Wake Development in a Three-cylinder Model within a Tunnel in Transitional Flow

ABSTRACT The characteristics of the flow and heat transfer in transitional flow are not clear and especially the lack of some reliable experimental data hinders the numerical study of the heat exchanger. Based on this, a two-dimensional time-resolved digital particle image velocimetry from the American-TSI-corporation was adopted. Experiments were carried out in an open-loop, recirculating water tunnel that operated at steady-state conditions. The experimental object is a three-cylinder with an equilateral triangle configuration having center-to-center distance ratio of 3. Reynolds number based on the tube diameter and the velocity of inlet is set at 70, 90, 120, 150, 200, 250 and 300. The flow parameters were quantified to research the effect of Reynolds number on flow field for supporting some facts to analyze the heat transfer. Time-mean flow field, turbulence statistics and velocity processed by proper orthogonal decomposition were investigated at different Reynolds numbers. The wake closure length, oscillation and Karman vortex in the wake of the three-cylinder model were discussed in detail.
Illumination-robust face recognition

The performance of a face recognition system is closely related to the amount of variation observed in face images. Illumination is a major source of such variations; therefore, compensating for illumination changes is a major requirement for face recognition algorithms. In this thesis, we approach the problem of face recognition by putting illumination compensation to the center of our framework. We describe an illumination-robust face recognition system that can recognize near-frontal human faces with changing facial expressions. We start developing our approach by first considering the problem of face recognition under varying illuminations with neutral facial expressions and frontal head poses. We develop a Segmented Linear Subspace algorithm that applies a collection of linear subspaces to a segmented image to achieve reliable recognition under varying illumination. We later relax the constraint on the facial expressions by carrying the Segmented Linear Subspace algorithm into the framework of the shape and texture representation. This representation is based on separating the face image into separate shape and texture vectors. We use the Segmented Linear Subspaces to model the texture component of this representation, which provides us robustness to varying facial expressions since the textures are normalized for shape changes. Computation of the shape and texture representation requires locating a number of facial features on the face image automatically, which is in general a difficult task. It is particularly challenging in our case because of the large illumination changes. To address this problem, we propose an Adaptive Active Appearance Model algorithm, which provides a fast and accurate way of locating landmark points on face images. We combine the Segmented Linear Subspace model and the Adaptive Active Appearance Model algorithm into a single system where we compensate for illumination and facial expression changes in a combined framework.
A 15‐year hail streak climatology for the Alpine region

In this study, we present a unique 15‐year hail streak climatology for Switzerland based on volumetric radar reflectivity. Two radar‐based hail detection products and an automatic thunderstorm‐tracking algorithm were reprocessed for the extended convective season (April–September) between 2002 and 2016. More than 1.1 million convective cells were automatically tracked over the full radar domain, and over 191,000 storms and 31,000 hail streaks in the considered subdomain were selected for analysis following consistency and robustness tests.