Miracle-dz/UniFAR-FTUs huggingface dataset:
The intrinsic ultraviolet continua of O stars

Low-resolution IUE spectra of O and B stars in open clusters have been obtained. The main-sequence B stars are used to derive UV extinction curves for the program clusters, and these curves are used to determine the intrinsic UV to visual colors of O stars in NGC 2244, Trumpler 14, and NGC 6231. These data are analyzed in conjunction with the dereddened colors of O stars with color excesses less than 0.15 mag to obtain a set of reliable UV colors for O3-9, class V-I stars. The results can be summarized as follows: none of the observed O stars have UV colors significantly bluer than a normal B0 V star, and the late O supergiants have significantly redder UV colors than main-sequence O stars, although this luminosity distinction appears to vanish for the early O stars. Several possible explanations for these unexpected results are considered, but none of the presently available nonstandard models are sufficiently developed to be definitively tested.
Measurement precautions for high-resistivity silicon solar cells

Several measurement characteristics have been identified that are unique to high-performance, high-resistivity silicon cells. These unique characteristics, which are due to features such as bulk carrier lifetimes on the order of 1 ms, excellent surface passivation, and light trapping, can lead to large performance measurement errors; however, they also offer insight into the physical mechanisms occurring in these devices. The characteristics that were found to have the largest influence on measured performance are described. These include a strong fill factor dependence on voltage sweep rate and direction, sublinear short-circuit current versus irradiance, light-soaking influence on open-circuit voltage and fill factor, and enhanced spectral response beyond 1100 nm due to optical light trapping. Cell measurements and analyses have included both small-area concentrator cells and large-area one-sun cells from various sources. <<ETX>>
Constrained Dynamics and Higher Derivative Systems in Modified Gravity

In this thesis, higher derivative theories and constrained dynamics are investigated in detail. In the first part of the thesis, we discuss how the Ostrogradski instability emerges in non-degenerate higher derivative theories in the context of a one-dimensional point particle where the position of the particle is a function only dependent on time. We show that the instabilities can only be removed by the addition of constraints if the original theory’s phase space is reduced. We then generalize this formalism to the most general higher derivative gravity theory where the action is not only linearly dependent on the Ricci scalar but also the quadratic curvature invariants in four-dimensional spacetime. We find that the instabilities can be removed by the judicious addition of constraints at the quadratic level of metric fluctuations around Minkowski and de Sitter backgrounds while the dimensionality of the original phase space is reduced. The constrained higher derivative gravity theory is ghost free as well as preserves the renormalization properties of higher derivative gravity, at the price of giving up the Lorentz invariance. In the second part of the thesis, we study the spherically symmetric static solution of a class of two scalar-field theory, where one of them is a Lagrange multiplier enforcing a constraint relating the value of the other scalar field to the norm of its derivative. We find the spherically symmetric static solution of the theory with an exponential potential. However, when we investigate the stability issue of the solution, the perturbation with the odd type symmetry is stable, while the even modes always contain one ghostlike degree of freedom.
The stability of an accelerating shock wave in an exponential atmosphere

The stability of a self-similar solution for an accelerating shock wave in an exponential atmosphere is studied using a linearized, normal mode analysis. An eigenvalue is determined by passing the solution through a critical point in the postshock flow. While instability is present over a wide range of parameters, the growth rate of the instability is slow. The shock front must travel four scale heights for a doubling in magnitude of a linear perturbation under the most favorable conditions for growth. The instability is expected to operate in a similar way for other accelerating shock fronts in steep density gradients. Substantial initial peturbations are needed for significant effects; this may occur in type Ia SNe and in the SN giving rise to Cas A. 27 refs.
Revisiting Sample Size and Number of Parameter Estimates: Some Support for the N:q Hypothesis

A number of authors have proposed that determining an adequate sample size in structural equation modeling can be aided by considering the number of parameters to be estimated. While this advice seems plausible, little empirical support appears to exist. A previous study by Jackson (2001), failed to find support for this hypothesis, however, there were certain limitations to the study that likely led to the lack of findings. This study revisits the issue with a design modified to be more sensitive to practically significant effects of sample size to parameter estimate ratio. Consequently, some support was found for this hypothesis, notably among overall fit measures and tests. Results indicate that higher values of the observations per parameter ratio had a positive effect for some measures of fit. However, the overall effect was small relative to absolute sample size.
The Noise Generated by the Collapse of a Cloud of Cavitation Bubbles

The focus of this paper is the numerical simulation of the dynamics and acoustics of a cloud of cavitating bubbles. The prototypical problem solved considers a finite cloud of nuclei that is exposed to a decrease in the ambient pressure which causes the cloud to cavitate. A subsequent pressure recovery then causes the cloud to collapse. This is typical of the perturbation experienced by a bubble cloud as it passes a headform or the blade of a ship propeller. The simulations employ the fully non-linear, non-barotropic, homogeneous flow equations coupled with the Rayleigh-Plesset dynamics for individual bubbles. This set of equations is solved numerically by an integral method. The computational results confirm the early speculation of Morch and his co-workers (Morch 1980 & 1981, Hanson et al. 1981) that an inwardly propagating shock wave may be formed in the collapse of a cavitating cloud. The structure of the shock is found to be similar to that of the steady planar shocks analyzed by Noordij and van Wijngaarden (1974). The shock wave grows rapidly not only because of the geometric effect of an inwardly propagating spherical shock but also because of the coupling of the single bubble dynamics with the global dynamics of the flow through the pressure and velocity fields (see also Wang and Brennen 1994). The specific circumstances which lead to the formation of such a shock are explored. Moreover, the calculations demonstrate that the acoustic impulse produced by the cloud is significantly enhanced by this shock-focusing process. Major parameters which affect the dynamics and acoustics of the cloud are found to be the cavitation number, [sigma], the initial void fraction, [alpha-zero], the minimum pressure coefficient of the flow, [C Pmin], the natural frequencies of the cloud, and the ratio of the length scale of low pressure perturbation to the initial radius of the cloud, [D/A-zero], where D can be, for example, the radius of the headform or chord length of the propeller blade. We examine how some of these parameters affect the far field acoustic noise produced by the volumetric acceleration of the cloud. The non-dimensional far-field acoustic impulse produced by the cloud collapse is shown to depend, primarily, on the maximum total volume of the bubbles in the cloud normalized by the length scale of the low pressure perturbation. Also, this maximum total volume decreases quasi-linearly with the increase of the cavitation number. However, the slope of the dependence, in turn, changes with the initial void fraction and other parameters. Non-dimensional power density spectra for the far-field noise are presented and exhibit the [equation] behavior, where n is between 0.5 and 2. After several collapse cycles, the cloud begins to oscillate at its natural frequency and contributes harmonic peaks in its spectrum.
Generic Summary Generation to Produce a Highlighted Version of Documents

Identifying the most relevant text information from online texts has become a standard task now that data is easily accessible. Consequently, summary generation has gained significant importance by reducing the amount of text a person has to read to get meaningful information from the text. The underlying field for this process is Natural Language Understanding (NLU), a sub-field of Natural Language Processing (NLP). NLU enables algorithms to understand and rewrite a text based on the original information. In this proposal, I will explore how a Convolutional Neural Network (CNN) can create a new approach for visualizing the critical aspects of a text. Instead of generating a shorter text, the output will be a version with the essential elements highlighted.
Visual PID Control of a Redundant Planar Parallel Robot

This paper deals with the position regulation problem of a redundant planar parallel robot for the case in which only the joint position measurements are available, and presents an image based visual servoing scheme to solve this problem. It uses Proportional Integral and Derivative algorithm to compute the torques for the robot active joints together a linear filter to obtain velocity estimates from visual position measurements and shows that the robot end-effector converges to the desired position. Lyapunov Stability Theory allows concluding closed loop stability without invoking the LaSalle-Krassovsky invariance principle. Experimental results are presented for a laboratory prototype and allow evaluating the performance of the closed loop system.Copyright © 2011 by ASME
Switching in a simple bistable nematic cell

This paper presents a theoretical examination of a nematic cell bounded by bistable weakly anchored surfaces. Switching between the two resultant equilibrium states is achieved by means of an electric field. In setting up the problem we identify a parameter whose measurement is important to the development of any device which relies upon weak anchoring. The results of this work are discussed in relation to the measurement of this constant.
Classification of economic data into multiple classes by means of evolutionary methods

In this contribution we deal with an automatic classification of economic data into multiple classes. A classifier created by grammatical evolution is used to determine the data sample membership into one of the defined classes. The grammar rules used for classifier structure creation are presented. The performance of our classifier is compared with multilayer perceptron neural network classifier and Kohonen neural network classifier. We used a survey data of consumer behaviour in food market in Czech Republic.
A Fault Diagnosis Method Based on Constrained Frequent Pattern Trees

Data mining is a broad term used to describe various methods for discovering patterns in data. A kind of pattern often considered is association rules, probabilistic rules stating that objects satisfying description A also satisfy description B with certain support and confidence. In this study, we first make use of the first-order predicate logic to represent knowledge derived from celestial spectra data. Next, we propose a concept of constrained frequent pattern trees (CFP) along with an algorithm used to construct CFPs, aiming to improve the efficiency and pertinence of association rule mining. The running results show that it is feasible and valuable to apply this method to mining the association rule and the improved algorithm can decrease related computation quantity in large scale and improve the efficiency of the algorithm. Finally, the simulation results of knowledge acquisition for fault diagnosis also show the validity of CFP algorithm.
HETEROEPITAXIAL GRAPHITE ON 6H-SIC(0001): INTERFACE FORMATION THROUGH CONDUCTION-BAND ELECTRONIC STRUCTURE

When annealed at elevated temperatures under vacuum, silicon carbide surfaces show a tendency towards graphitization. Using the sensitivity of empty conduction-band states dispersion towards the structural quality of the overlayer, we have used angular-resolved inverse photoemission spectroscopy ~KRIPES! to monitor the progressive formation of crystalline graphite on 6 H-SiC(0001) surfaces. The KRIPES spectra obtained after annealing at 1400 °C are characteristic of azimuthally oriented, graphite multilayers of very good singlecrystalline quality. For lower annealing temperatures, the ordered interface already presents most of the fingerprints of graphite as soon as 1080 °C. The observation of unshifted p* states, which reveals a very weak interaction with the substrate, is consistent with the growth of a van der Waals heteroepitaxial graphite lattice on top of silicon carbide, with a coincidence lattice of (6 )36))R30° symmetry. The growth of the first graphene sheet proceeds on top of adatoms characteristic of the ( )3))R30° reconstruction. These adatoms reduce the chemical reactivity of the substrate. A strong feature located at 6.5 eV above the Fermi level is attributed to states derived from Si vacancies in the C-rich subsurface layers of the SiC substrate. This strongly perturbed substrate can be viewed as a diamondlike phase which acts as a precursor to graphite formation by collapse of several layers. In this framework, previously published soft x-ray photoemission spectra find a natural explanation. @S0163-1829 ~98! 06347-4#
The Balian–Low theorem for a new kind of Gabor system

The Balian–Low theorem expresses the fact that time–frequency concentration is incompatible with non-redundancy for Gabor systems. In this article, the Balian–Low theorem is established for a new kind of Gabor systems associated with a phase function θ(t) satisfying certain assumptions. Meanwhile, some properties of the corresponding generalized Zak transform are shown and explicit examples of the phase function θ(t) are provided.
A New Method of Nonlinear Analysis for Shaping and Threshold Actions

For a dynamical system \(\textbf{\itshape \dot{x}}{=}\textbf{\itshape F}(\textbf{\itshape x})\), an inflector C is defined by C={ x |( A -λ I ) F =0, | A -λ I |=0}, where the matrix A denotes ∂ F /∂ x . It is seen that C consists of inflection points of trajectories and singular points. The inflector C plays an important role for the threshold and shaping actions in many dynamical systems. As an example, the BVP model of an excitable membrane is investigated by means of the inflector C, and some knowledge about continuous threshold phenomena of the BVP model is obtained.
The development of an electron gun for performing ultrafast electron diffraction experiments

This thesis aims to comprehensively discuss ultrafast electron di raction and its role in temporally resolving ultrafast dynamics on the molecular level. Theory on electron pulses and electron pulse propagation will be covered, but the main focus will be on the method, equipment and experimental setup required to generate sub-picosecond electron pulses, which are needed to perform time resolved experiments. The design and construction of an electron gun needed to produce the electron pulses will be shown in detail, while preliminary pulse characterization experiments will also be illustrated. An introduction into the theory of electron di raction patterns and how to interpret these di raction patterns will conclude the thesis. Stellenbosch University http://scholar.sun.ac.za
Inferences for a semiparametric model with panel data

SUMMARY In a longitudinal study, suppose that, for each subject, repeated measurements of the response variable and covariates are collected at a set of distinct, irregularly spaced time points. We consider a semiparametric model which relates the mean of the response variable at each time point proportionally to a function of a time-dependent covariate vector to analyse such panel data. Inference procedures for regression parameters are proposed without involving any nonparametric function estimation for the nuisance mean function. A dataset from a recent AIDS clinical trial is used to illustate the new proposal.
Sampling Exchangeable and Hierarchical Marshall-Olkin Distributions

The seminal Marshall-Olkin distribution is given by the following d-dimensional frailty model: independent exponentially distributed random variables represent the arrival times of shocks that destroy subgroups of a vector with d components. Sampling the resulting random vector of extinction times along the lines of this stochastic representation is conceptually straightforward. Firstly, all possible shocks are sampled. Secondly, the extinction time of each component is computed. However, implementing this sampling scheme involves 2 d − 1 random variables and requires finding the minimum of a set with 2 d−1 elements for each component. Thus, the overall effort is exponentially increasing in the number of considered components, preventing the general model from being used in high-dimensional simulation studies. This problem is overcome for the subfamily of exchangeable Marshall-Olkin distributions, for which a sampling algorithm with polynomial effort in d, an upper bound is 𝒪(d 3), is presented. In a second step, it is shown how hierarchical models are constructed from exchangeable structures and how models with alternative univariate marginal laws are obtained. The presented algorithm is then adapted to sample such structures as well. Finally, a small case study in the context of portfolio credit risk is presented.
Tri-harmonic boundary value problems in a sector

This paper is devoted to the construction of a tri-harmonic Green function and a tri-harmonic Neumann function in a sector with angle explicitly, as well as a tri-harmonic Neumann function in the unit disk. Then the related Dirichlet and Neumann problems for the tri-Poisson equation are discussed, respectively.
Bibliometric analysis of spatio-temporal model using a general product-sum based on a hydrological distance

In the last two decades, the number of model developments in the field of Geostatistics increased rapidly, especially in the Spatio-temporal models. Almost of these models are based on Euclidean distance, only a few which based on non-Euclidean distance. The purpose of this study is to analyze and visualize the types of literatures on stationary Spatio-temporal models that utilize General Product-sum and Hydrological distance through bibliometric analysis methods, by considering a set of bibliometric metrics, including productive and impact measures, methods analysis, and co-authorships analysis. Scientific research works related to Spatio-temporal models using the product-sum field that consider hydrological aspects, published between 2002 and 2022 are reviewed. Some of the most relevant research works in this field and some of the newest trends are collected during September 2022 from Google Scholar, Scopus and Dimensions databases. The literature search method is carried out in two steps. Firstly, literature sources were obtained from Google Scholar, Scopus and Dimensions. Secondly, meta-analysis is performed using Harzing's Publish or Perish and VOSviewer software program. Total of 488 articles related to Spatio-temporal product-sum, and 8 articles related to Spatio-temporal product-sum based on hydrologic distance are selected. The analysis result shows that the proposed topic “Spatio-temporal model using product-sum based on hydrologic distance” has a different significant attribute from the existing research works, i.e., the hydrologic distance. Therefore, the proposed topic can be considered has a novelty.
Distinctive microbiota of delayed healing of oral mucositis after radiotherapy of nasopharyngeal carcinoma

Background Oral mucositis is the most common complication after radiotherapy of nasopharyngeal carcinoma (NPC). Previous studies had revealed that oral microbiota took great alteration soon after and during radiotherapy. Here, we aimed to investigate if the alteration of oral microbiota was related to delayed healing of oral mucositis after six month of radiotherapy. Methods We recruited 64 NPC patients and collected samples after six month of radiotherapy. 32 patients were included into normal healing group (N), 22 patients were mild delayed healing group (M), while 10 patients were severe delayed healing group (S). 16S rRNA gene sequencing was used to assess and identify oral microbiota alteration. Results The diversity of oral microbial communities was not significantly different. Composition of oral microbial was huge different among S group, for the Actinobacteria and Veillonella were significantly increased, which showed significant dysbiosis of the oral microbiome. Functional analysis of metabolic pathways of oral microbiota demonstrated that degradation of organic acids and amino acids were significantly increased in S group. Moreover, phenotype analysis found that relative abundance of aerobic and biofilm formation were higher in S group. We also found the Actinobacteria co-occurred with Veillonellaceae, but anti-occurred with other biofilm oral bacteria. These two biomarkers may be predictable for severe delayed healing of oral mucositis after radiotherapy. Conclusion This study suggests a potential association between oral microbiome and delayed healing of oral mucositis. The Actinobacteria and Veillonellaceae may be biomarkers in predicting the risks for the severe delayed healing of oral mucositis after radiotherapy of NPC.