Miracle-dz/UniFAR-FTUs huggingface dataset:
The dark side of curvature

Geometrical tests such as the combination of the Hubble parameter H(z) and the angular diameter distance dA(z) can, in principle, break the degeneracy between the dark energy equation of state parameter w(z), and the spatial curvature Ωk in a direct, model-independent way. In practice, constraints on these quantities achievable from realistic experiments, such as those to be provided by Baryon Acoustic Oscillation (BAO) galaxy surveys in combination with CMB data, can resolve the cosmic confusion between the dark energy equation of state parameter and curvature only statistically and within a parameterized model for w(z). Combining measurements of both H(z) and dA(z) up to sufficiently high redshifts z ∼ 2 and employing a parameterization of the redshift evolution of the dark energy equation of state are the keys to resolve the w(z)−Ωk degeneracy.
Hamiltonian actions and Lagrangian homogeneous submanifolds

We consider a connected symplectic manifold $M$ acted on properly and in a Hamiltonian fashion by a connected Lie group $G$. Inspired to the recent paper \cite{gb2}, see also \cite{ch} and \cite{pacini}, we study Lagrangian orbits of Hamiltonian actions. The dimension of the moduli space of the Lagrangian orbits is given and we also describe under which condition a Lagrangian orbit is isolated. If $M$ is a compact K\"ahler manifold we give a necessary and sufficient condition to an isometric action admits a Lagrangian orbit. Then we investigate Lagrangian homogeneous submanifolds on the symplectic cut and on the symplectic reduction. As an application of our results, we give new examples of Lagrangian homogeneous submanifolds on the blow-up at one point of the complex projective space and on the weighted projective spaces. Finally, applying Proposition \ref{slice} that we may call \emph{Lagrangian slice theorem} for group acting with a fixed point, we give new examples of Lagrangian homogeneous submanifolds on irreducible Hermitian symmetric spaces of compact and noncompact type.
An investigation into the use of atomic datasets in simulations of the Ni-like gadolinium x-ray laser

The effect of differing the datasets used in the modelling of the Ni-like Gd x-ray laser (XRL) is examined through the 1.5D hydro-atomic code, EHYBRID. Two atomic datasets, including energy levels and radiative and collisional excitation rates, are used as input data for the code. It is found that the behaviour of the XRL is somewhat different than might be expected from superficial examination of the atomic data. The similarities in the gain profiles at low densities are found to have encouraging implications in our attempts to model XRLs.
Semi-analytic calculation of the gravitational wave signal from the electroweak phase transition for general quartic scalar effective potentials

Upcoming gravitational wave (GW) detectors might detect a stochastic background of GWs potentially arising from many possible sources, including bubble collisions from a strongly first-order electroweak phase transition. We investigate whether it is possible to connect, via a semi-analytical approximation to the tunneling rate of scalar fields with quartic potentials, the GW signal through detonations with the parameters entering the potential that drives the electroweak phase transition. To this end, we consider a finite temperature effective potential similar in form to the Higgs potential in the Standard Model (SM). In the context of a semi-analytic approximation to the three dimensional Euclidean action, we derive a general approximate form for the tunneling temperature and the relevant GW parameters. We explore the GW signal across the parameter space describing the potential which drives the phase transition. We comment on the potential detectability of a GW signal with future experiments, and physical relevance of the associated potential parameters in the context of theories which have effective potentials similar in form to that of the SM. In particular we consider singlet, triplet, higher dimensional operators, and top-flavor extensions to the Higgs sector of the SM. We find that the addition of a temperature independent cubic term in the potential, arising from a gauge singlet for instance, can greatly enhance the GW power. The other parameters have milder, but potentially noticeable, effects.
Identification of Dual-Active-Bridge converter transfer function

Frequency-domain identification method of the Dual-Active-Bridge converter control-to-output and closed loop control transmittances by means of the Matlab (tfest function) is presented in this paper. The phase shift modulation is used as the converter control scheme. The closed loop control was designed basing exclusively on the estimated control-to-output (the control object) transfer function. Presented experimental and computer simulation results are in form of the Bode plots and the output voltage step responses. Streszczenie. W artykule zaprezentowano metodę częstotliwościową do identyfikacji transmitancji podwójnego mostka H z wykorzystaniem pakietu Matlab (tfest funkcja) zarówno samego członu energoelektronicznego, jako obiektu regulacji przy zmianie kąta przesunięcia pomiędzy stroną pierwotną i wtórną, jak i kompletnego zamkniętego układu regulacji napięcia wyjściowego. Zamknięty układ regulacji zaprojektowano wyłącznie na podstawie estymowanej transmitancji obiektu. W artkule zaprezentowano wyniki eksperymentalne wraz z wynikami z modelu symulacyjnego, w formie charakterystyk amplitudowo-fazowych oraz odpowiedzi na skok jednostkowy. (Identyfikacja transmitancji konwertera z podwójnym mostkiem aktywnym)
Spatio-temporal stochastic hybrid models of biological excitable membranes

A large number of biological systems are intrinsically random, in particular, biological excitable membranes, such as neuronal membranes, cardiac tissue or models for calcium dynamics. The present thesis is concerned with hybrid stochastic models of spatio-temporal dynamics of biological excitable membranes using Piecewise Deterministic Markov Processes (PDMPs). This class of processes allows a precise mathematical description of the internal noise structure of excitable membranes. Overall the aim of the thesis is two-fold: On the one hand, we establish a general hybrid modelling framework for biological excitable membranes and, on the other hand, we are interested in a general advance of PDMP theory which the former necessitates. Regarding the first aim we exemplify the modelling framework on the classical Hodgkin-Huxley model of a squid giant axon. Regarding the latter we present a general PDMP theory incorporating spatial dynamics and present tools for their analysis. Here we focus on two aspects. Firstly, we consider the approximation of PDMPs by deterministic models or continuous stochastic processes. To this end we derive as general theoretical tools a law of large numbers for PDMPs and martingale central limit theorems. The former establishes a connection of stochastic hybrid models to deterministic models given, e.g., by systems of partial differential equations. Whereas the latter connects the stochastic fluctuations in the hybrid models to diffusion processes. Furthermore, these limit theorems provide the basis for a general Langevin approximation to PDMPs, i.e., certain stochastic partial differential equations that are expected to be similar in their dynamics to PDMPs. Secondly, we also address the question of numerical simulation of PDMPs. We present and analyse the convergence in the pathwise sense of a class of simulation methods for PDMPs in Euclidean space.
Iterative control method of voltage source converters for various high‐power applications

: High-voltage and high-power voltage source converters (VSCs) are usually operated at low switching frequencies to minimise the switching losses. This study presents a new control method suitable for low switching frequencies. It consists of two stages. In the first stage, a simple proportional controller is used to suppress any overvoltage or overcurrent during the transients. Then, after the control variables have settled to steady-state values, the iterative controller is activated to finely adjust the modulation index and firing angle of the converter to fulfil the control objectives. To justify the proposed control method, various control objectives are realised in a 10 MVA VSC system, and the results are validated by PSCAD/EMTDC and hardware-in-the-loop simulation. The results show that state variables converge within a few iterative steps, and the transient response is sufficiently fast. The proposed method is shown to perform better than the conventional PI control for eliminating the power imbalance and DC second harmonics due to the imbalance at the grid voltage.
Fermi-LAT constraints on dark matter annihilation cross section from observations of the Fornax cluster

We analyze 2.8-yr data of 1–100 GeV photons for clusters of galaxies, collected with the Large Area Telescope onboard the Fermi satellite. By analyzing 49 nearby massive clusters located at high Galactic latitudes, we find no excess gamma-ray emission towards directions of the galaxy clusters. Using flux upper limits, we show that the Fornax cluster provides the most stringent constraints on the dark matter annihilation cross section. Stacking a large sample of nearby clusters does not help improve the limit for most dark matter models. This suggests that a detailed modeling of the Fornax cluster is important for setting robust limits on the dark matter annihilation cross section based on clusters. We therefore perform the detailed mass modeling and predict the expected dark matter annihilation signals from the Fornax cluster, by taking into account effects of dark matter contraction and substructures. By modeling the mass distribution of baryons (stars and gas) around a central bright elliptical galaxy, NGC 1399, and using a modified contraction model motivated by numerical simulations, we show that the dark matter contraction boosts the annihilation signatures by a factor of 4. For dark matter masses around 10 GeV, the upper limit obtained on the annihilation cross section times relative velocity is ⟨σν⟩≲(2–3) × 10−25 cm3 s−1, which is within a factor of 10 from the value required to explain the dark matter relic density. This effect is more robust than the annihilation boost due to substructure, and it is more important unless the mass of the smallest subhalos is much smaller than that of the Sun.
An Inexact Coordinate Descent Method for the Weighted $l

The purpose of this paper is to propose an inexact coordinate descent (ICD) method for solving the weighted $l _{1}$ -regularized convex optimization problem with a box constraint. The proposed algorithm solves a one dimensional subproblem inexactly at each iteration. We give criteria of the inexactness under which the sequence generated by the proposed method converges to an optimal solution and its convergence rate is at least $R$ -linear without assuming the uniqueness of solutions.
Pyroelectric response and temperature-induced α-β phase transitions in α-In2Se3 and other α-III2VI3 (III  =  Al, Ga, In; VI  =  S, Se) monolayers

The pyroelectric response of materials is a promising phenomenon that is used in many applications, but two-dimensional (2D) pyroelectricity has not received due attention. Here we report ab initio molecular dynamics simulations to investigate the pyroelectric effect in α-III2VI3 (III = Al, Ga, In; VI = S, Se) monolayers, an emerging class of 2D pyroelectric materials. The in-plane and out-of-plane spontaneous polarizations are found to be robust at room temperature. We demonstrate large pyroelectric response in these materials that is associated with temperature-induced ferroelectric-to-paraelectric phase transitions. Identifying the high-temperature nonpolar phase as the β-phase, we demonstrate strong displacive character in the α-β phase transition, which is achieved through relative displacements of the top three and bottom two atomic sublayers in opposite directions. The present work unravels and highlights the primary pyroelectric effect and the α-β phase transitions that are responsible for the promising pyroelectricity in α-III2VI3 monolayers.
State of the Art Compendium of Macro and Micro Energies

In the span of past few decades, population, urbanization and industrialization have transformed the mankind living standard and dynamics of the nature. Certainly, energy is the basic need for all living organisms. Energy is the route towards the economic growth. The evidence shows that the countries faced with energy crises are left behind in the economic activities; as a result, people are deprived. This study reviewed the available renewable energy resources and potential with positive and negative aspects. This study comprehensively discusses the renewable macro and micro energy resources studied in the past two decades reported in various studies. The paper is divided into two sections; the first section discusses the energy produced in the macro level and the second section discusses the energy produced using different strategies and techniques in the micro level. The potential and positive outcomes of the energy resources were identified. New paradigm of micro energies and importance of reusing the available resource of micro energy using different resources like energy harvesting on the road surface, vibration, airflow, radio frequency and thermal energy etc. were discussed. Lastly, the study focus does not only review but also finds the potential and opportunities for the researchers in the future to utilize the renewable energy resources.
A CMOS Highly Linear Doherty Power Amplifier With Multigated Transistors

This paper presents a highly linear and power back-off efficiency-enhanced Doherty power amplifier (PA) fully integrated into CMOS. The proposed Doherty PA employs a transformer-based quadrature signal generator, multigated transistors (MGTRs) in the main PA, Class-C mode auxiliary PA, and synthesized transformer-based Doherty parallel output network with the second-harmonic control circuits. An on-chip 8-port transformer-based quadrature signal generator is designed within a single transformer footprint ( $340\,\,\mu \text{m}\,\,\times 340\,\,\mu \text{m}$ ) and provides 0°/−90° differential signals to the main/auxiliary PAs. The MGTR in the main PA is implemented using four transistors with different sizes and biases to generate and extend a near-zero $\text {g}_{\text {m3}}$ operation region. Moreover, an on-chip transformer-based Doherty parallel output network with the second-harmonic control circuits shows higher passive efficiency compared with a conventional Doherty parallel output network and provides low second-harmonic loads to the main/auxiliary PAs. Both the proposed MGTR in the main PA and the second-harmonic control circuits in the main/auxiliary PAs suppress the third-order intermodulation distortion of the Doherty PA. This results in a substantial linearity improvement of the Doherty PA, which can support high-order modulation signals and reduce or even eliminate the need for digital predistortion (DPD). As a proof-of-concept design, a 5.8 GHz Doherty PA is implemented in a standard 55 nm bulk CMOS process. The proposed Doherty PA exhibits 27.2 dBm saturated output power with 24.5% power-added efficiency (PAE) at 5.8 GHz. The measured error vector magnitude with 40/80 MHz of 64-QAM/256-QAM is 2.5%/1.8% with 20.7/17 dBm average output power, 9.5%/5.3% average PAE, and −33.2/−36.3 dBc adjacent channel leakage ratio without any DPD.
Error Identification And Correction By Using Fault Tolerant Parallel Filter

: Digital filters are commonly utilized in signal handling as well as interaction systems. In many cases, the dependability of those systems is vital, as well as mistake forgiving filter executions are required. Throughout the years, lots of methods that manipulate the filters' framework and also residential properties to attain mistake resistance have actually been suggested. As innovation ranges, it makes it possible for extra complicated systems that include several filters. In those intricate systems, it prevails that a few of the filters run in parallel, as an example, by using the very same filter to various input signals. Just recently, a basic method that manipulates the visibility of identical filters to accomplish mistake resistance has actually existed. In this short, that concept is generalized to reveal that identical filters can be shielded making use of mistake improvement codes (ECCs) in which each filter is the matching of a little bit in a typical ECC. This brand-new system enables much more effective security when the variety of identical filters is huge. The strategy is examined making use of a study of identical limited impulse action filters revealing the efficiency in regards to security and also application expense.
Sampling Weights, Model Misspecification and Informative Sampling: A Simulation Study

Abstract Linear mixed-effects (LME) models analyze data that contain complex patterns of variability, specifically involving different nested layers. While LME models can match well the stratification and clustering of survey data, it is not clear how sampling weights should be incorporated into LME estimates. This report uses twelve simulation studies to compare two published methods of inserting sampling weights into LME estimates, Pfeffermann et al. (1998), denoted PSHGR, and Rabe-Hesketh and Skrondal (2006), denoted RHS. There are five main conclusions based on these simulations. 1) The PSHGR and RHS point estimates are very similar, with differences due to numerical instabilities in the estimation procedures. 2) Confidence intervals based on the sandwich estimator and the design based estimator of the variances provide similar coverage when there is no model misspecification. However, when there is model misspecification, the design-based variance estimator has unexpectedly large coverage, implying that the variance estimates are too large. 3) When there is model misspecification that does not induce informative sampling, weighted estimates do not reduce bias of the estimators. 4) When there is informative sampling, the weighted estimators do reduce the bias of the point estimates, though they do not eliminate it. 5) The unweighted estimate has the smallest variance. When there is informative sampling, the unweighted estimates are biased. The weighted unscaled estimate corrects the bias in the fixed effects, but produces more bias in the random effects. The scaled 1 weightings remove the bias in the fixed effects, and overcorrect for the weighted unscaled bias in the random effects. The scaled 2 weightings remove the bias in the fixed effects and are in between the weighted unscaled and weighted scaled 1 bias in the random effects.
On the theory of the modal expansion method for the EM fields inside a closed volume

The theory of the modal expansion method for the transient electromagnetic fields inside a closed region is reviewed. Although the concept of modal expansion is well known in the theory of electromagnetism, this formulation may make it more comprehensive where the scope of applicability, the effect of surface excitations, and the introduction of real modal fields to avoid complex notations in the time-domain formulation is concerned. It can be shown that, without resorting to the explicit expression for the quasi-static solution, which should be used to satisfy the inhomogeneous boundary conditions, the transient responses of EM fields inside a closed region could be expressed explicitly in terms of the natural modes of the system. This formulation assumes an arbitrarily inhomogeneous anisotropic material, volume and surface sources of arbitrary temporal and spatial dependence, and arbitrary initial electric and magnetic field distributions. For simplicity, the effects of losses are neglected in this formulation.
AdS/CFT beyond the $N = 4$ SYM paradigm

In this thesis we present studies in the AdS/CFT correspondence that intend to push the present knowledge beyond the $N = 4$ super Yang-Mills (SYM) paradigm. The first part is concerned with the study of non-supersymmetric deformations of $N = 4$ SYM (which still are in the $N = 4$ universality class). For non-supersymmetric CFT’s at Large $N$ we explore the correspondence between string theory tachyons in the bulk and instabilities on the boundary effective action. The operators dual to AdS tachyons have anomalous dimensions that are purely complex numbers. We give a prescription for calculating the mass of the tachyon from the field theory side. Moreover, we apply this general dictionary to the case of intersecting D7 flavor branes in $AdS_{5} \times S^{5}$ and obtain the mass of the open string tachyon that is dual to the instability in the mesonic sector of the theory. In the second part we present work aiming at finding string theory duals for gauge theories beyond the $N = 4$ universality class, i.e. theories that have genuinely less supersymmetry and unquenched flavor. Arguably the next simplest example after $N = 4$ SYM is $N = 2 SU (N_{c})$ SYM coupled to $N_{f} = 2N_{c}$ fundamental hypermultiplets. The theory admits a Veneziano expansion of large $N_{c}$ and large $N_{f}$, with $N_{f}/N_{c}$ and $\lambda = g^{2}N_{c}$ kept fixed. The topological structure of large $N$ diagrams invites a general conjecture: the flavor-singlet sector of a gauge theory in the Veneziano limit is dual to a closed string theory. We present the one-loop Hamiltonian for the scalar sector of $N = 2$ superconformal QCD and study this integrability of the theory. Furthermore, we explore the chiral spectrum of the protected operators of the theory using the one-loop anomalous dimensions and, additionally, by studying the index of the theory. We finally search for possible AdS dual trying to match the chiral spectrum. We conclude that the string dual is a sub-critical background containing both an $AdS_{5}$ and an $S^{1}$ factor.
Solar activity and cosmic ray intensity variation

In this correlative analysis we have taken monthly data of Grouped Solar Flare Index (GSF), instead of sunspot numbers, and cosmic ray intensity (CRI) for the solar cycles 20 to 23. These three solar parameters show a positive and high correlation amongst themselves. These solar parameters are again correlated with cosmic ray intensity for three successive solar cycles 20 to 23. We have used sunspot number and grouped solar flares as reliable solar parameters. A detailed correlative study has been done by using "the running cross correlation" method. It has been found that the anti-correlation between GSF and CRI is strong during the period from 1950 to 2003. Pressure corrected cosmic ray intensity data have been taken for mid latitude station Kiel. However, other stations give same result as for the mid latitude station. From statistical and correlative analysis, we observe a negative and high correlation between solar activity and cosmic rays. Our results support the earlier findings which were observed for solar cycle 18 to 20. The observed cosmic ray modulation for these periods, when compared with other solar activity indices, shows the appropriateness of the (GSF) as solar activity index instead of sunspot numbers. The effects are found to be distinctly different in the four solar cycles 20 to 23, when the most appropriate solar activity index (GSF) in used, which necessitates further studies on short-term basis.