Miracle-dz/UniFAR-FTUs huggingface dataset:
A Optimization Model of Correlation Matrix

Hamilton and Pelletier have brought forward the regime switching model for dynamic correlation matrix. It is especially for the variance time-varying financial multiple time series. In this paper, we use random matrix theory to improve the correlation matrix, which removed the noise, leaving the true information. We also present an empirical application use China's stock market data to optimize portfolio which illustrates that our model can have achieved good results.
Influences of the MJO on intraseasonal rainfall variability over southern Iran

Using daily rainfall data from 183 stations, influences of the Madden‐Julian Oscillation (MJO) on precipitation over southern Iran are examined. When composites of daily rainfall anomalies are constructed by introducing eight phases in the time evolution, wet conditions are observed in MJO phases 1–2 and 7–8. During these phases, atmospheric circulation anomalies favor moisture advection from the western Indian Ocean to southern Iran. In contrast, dry conditions during MJO phases 3 to 6 are associated with advection of drier air from the north.
AN ANALYTICAL MODEL FOR SHORT-CHANNEL ORGANIC THIN-FILM TRANSISTORS

An analytical model that describes the operation of α‐hexathienylene (α‐6T) thin‐film‐transistors (TFTs) is presented. The current‐voltage characteristics of TFTs with channel lengths ranging from 1.5 to 25 μm have been calculated after modifying the equations that describe the characteristics of conventional enhancement mode p‐channel metal‐oxide‐semiconductor field‐effect‐transistors. The calculated current‐voltage characteristics are compared with the experimental data. The model takes into account the non‐inversion‐mode operation of α‐6T TFTs as well as short channel effects such as series parasitic resistance, channel length shortening, apparent threshold voltage, and apparent field‐effect mobility. Furthermore, the field‐effect mobility is observed to depend on longitudinal electric fields which are higher than 105 V/cm, and this effect is also included in the model. The highest field‐effect mobility measured is 0.03 cm2/V s. From an analysis of measured data, the carrier mobility of field‐induced p.
A feasible directions algorithm for optimal control problems with control and terminal inequality constraints

Control constraints, because they are nondifferentiable in the space of control functions, are difficult to cope with in optimization algorithms not of the penalty function type. In feasible directions type algorithms a search direction is obtained by solving a subproblem which has a fixed constraint set S chosen a priori to make this subproblem simple to solve. In this paper control constraints are dealt with by using them to define, at the current control u , a constraint set S(u) for the search direction subproblem. This enables control constraints to be easily handled.
DIFFERENTIABLE ACTIONS OF HOMOTOPY SEVEN SPHERES, II.

Abstract : The paper presents a theorem which shows that there are exactly six unoriented homotopy 7-spheres not diffeomorphic to one another such that on each of them there is a free differentiable action of the circle group. Moreover, on any homotopy 7-sphere, if there exists a free differentiable action of the circle group, then there are infinitely many topologically distinct from one another.
Analysis of Matrix Models as Tools for Amphibian Conservation

La plupart des etudes sur le declin des amphibiens ou la disparition de populations se sont concentrees sur l'identification de l'amplitude et de l'etendue de ces phenomenes chez de nombreuses especes. Les modeles de dynamique des populations sont couramment utilises en biologie de la conservation de nombreux vertebres, mais encore rarement pour les Amphibiens. Dans cet article, je decris l'utilisation de ces modeles quantitatifs pour estimer la croissance des populations de deux especes d'Amphibiens. La premiere espece est la Grenouille rousse Rana temporaria. C'est une espece commune en Europe, colonisant une gamme d'environnement etendue, de la plaine a l'etage alpin. L'autre espece est la Salamandre de Lanza Salamandra lanzai, qui, au contraire, est tres localisee dans les Alpes. Les parametres demographiques et taux de survie sont relativement bien connus, et des analyses de sensibilite ont recemment ete publiees chez ces deux especes, a partir de la construction de modeles structures en âge, pour identifier les parametres les plus influants sur la croissance des populations. Les resultats principaux de ces etudes sont decrits et compares, et utilises pour proposer des directives d'actions de conservation pour chacune des especes.
Microstructural evolution of Mn-rich antiferromagnetic Mn–Cu alloy under temperature field

This paper reports the microstructural evolution during forward and reverse martensitic transformations as temperature changes in Mn-rich Mn–Cu alloy. The driving force of martensitic transformation and transformation strain in time-dependent Ginzburg–Laudau kinetic equation is considered as functions of temperature. The computer simulation by using a three-dimensional phase-field theory shows that fct (011) twin martensites grow up with decreasing temperature and shrink with increasing temperature under martensitic transformation temperature, Ms. The forward and reverse processes are entirely reversible and show a very small hysteresis. It is proved that the relaxation of stored strain energy during the forward martensitic transformation plays a key role when reverse martensitic transformation takes place. The simulated results are consistent with experiments.
How do tax technology and controversy expertise affect tax disputes?*

Given the rising number, magnitude, and harshness of tax disputes between firms and tax authorities, firms increasingly call on tax technology and controversy expertise to try to resolve these disputes. This study investigates how tax technology embedded in the firm’s Tax Risk Management System (TRMS) and the expertise of tax controversy managers affect dispute outcomes and compliance incentives. Using a game-theoretic model, we derive equilibrium strategies for a tax manager’s compliance effort, a controversy manager’s dispute resolution effort, and a tax authority’s litigation decision. Absent a controversy manager, we find that improving a firm’s TRMS quality unambiguously decreases the litigation probability. However, in the presence of a controversy manager, we surprisingly find that improving TRMS quality crowds out compliance efforts and can increase litigation probability. Overall we find that a high-quality TRMS is essential to take advantage of the dispute resolution function of a controversy manager.
Search for Ap stars in open clusters

Low-dispersion spectrograms of 62 stars in 13 open clusters were observed in the intrinsic color range -- 0.13 < B -- V < +0.06 in order to search for Ap stars. The purpose was to contribute to the statistics of the occurrence of Ap stars in homogeneous age groups, which is necessary as a critical test for some theories regarding the nature of Ap stars. Three new Ap stars were positively identified (all silicon-enhanced), and six other marginal candidates were noted. (auth)
E-PROPER SADDLE POINTS AND E-PROPER DUALITY IN VECTOR OPTIMIZATION WITH SET-VALUED MAPS

In this paper, based on a kind of unified proper efficiency named as $E$-Benson proper efficiency, we present $E$-proper saddle points theorems and $E$-proper duality results including as weak duality and strong duality theorems of vector optimization problems with set-valued maps. Our main results unify and extend the cases of proper saddle points and proper duality as well as $\varepsilon$-proper saddle points and $\varepsilon$-proper duality.
Numerical studies of the interplay between self‐phase modulation and dispersion for intense plane‐wave laser pulses

A computer algorithm is presented which allows simultaneous consideration of self‐phase modulation and dispersion for predicting temporal shape changes during the propagation of plane‐wave intense light pulses. The algorithm entails considering propagation alternately in regions where only one of the two above effects is operative. It is shown for clear materials that the parameters characterizing propagation are the nonlinear index change, the wavelength λ, the relaxation time of the nonlinearity, and the disperison parameter λ3(d2n/dλ2). The thickness of material over which a pulse will significantly reshape is found to be √λ times the geometric length of the pulse divided by the square root of the product of the dispersion parameter and the maximum nonlinear index. It is demonstrated that dispersion significantly modifies the self‐steepening concept of DeMartini, Townes, Gustafson, and Kelley. Numerical simulations of propagation in CS2 indicate that, after sufficient travel, a shock can form on the le.
The separation of synchrotron and bremsstrahlung radio emission in spiral galaxies

Spectra consisting of both bremsstrahlung and synchrotron components are fit to the observed radio-continuum spectra of 41 spiral galaxies. The detection of the bremsstrahlung component in 11 galaxies is reported. Very low upper limits are placed on another 20. For the remaining 11, model spectra cannot be fit with statistical significance. It is found that the thermal fraction (ratio of bremsstrahlung to total radio emission) spans at least two orders of magnitude among the 31 galaxies with good fits. The spectral index of the synchrotron component is found to vary over a larger range than previously suggested. A possible trend in the thermal fraction with the van den Bergh luminosity class is reported. The dependence is discussed in the context of cosmic-ray production, star formation, and theories of spiral structure, and it is concluded that, if the correlation is real, a three-way relationship may exist. 31 references.
New formulae for the Bernoulli and Euler polynomials at rational arguments

We prove theorems on the values of the Bernoulli polynomials B,(x) with n = 2, 3, 4, . , and the Euler polynomials En(x) with n = 1, 2, 3, . for 0 < x < 1 where x is rational. Bn(x) and En(x) are expressible in terms of a finite combination of trigonometric functions and the Hurwitz zeta function 4(z, a). The well-known argument-addition formulae and reflection property of Bn (x) and En (x), extend this result to any rational argument. We also deduce new relations concerning the finite sums of the Hurwitz zeta function and sum some classical trigonometric series.
Impact of Data Assimilation on Cost-Accuracy Tradeoff in Multifidelity Models

Observable phenomena can often be described by alternative models with different degrees of fidelity. Such models typically contain uncertain parameters and forcings, rendering predictions of the state variables uncertain as well. Within the probabilistic framework, solutions of these models are given in terms of their probability density functions (PDFs). In the presence of data, the latter can be treated as prior distributions. Uncertainty and assimilation of measurements into model predictions, e.g., via Bayesian updating of solution PDFs, pose a question of model selection: Given a significant difference in computational cost, is a lower-fidelity model preferable to its higher-fidelity counterpart? We investigate this question in the context of multiphase flow in heterogeneous porous media whose hydraulic properties are uncertain. While low-fidelity (reduced-complexity) models introduce a model error, their moderate computational cost makes it possible to generate more realizations, which reduces the .
Experimental Study on Deformation and Strength Characteristics of Sandstone with Different Water Contents

Water content is one of the most significant factors affecting the rock deformation and strength characteristics in the rock enginnering. To reveal the deformation and strength characteristics of sandstone with different water contents, the compressive strength tests for sandstone specimens under four different confining levels were carried out and an exponential formulation was put forward to predict the reduction in cohesive strength with water content increasing. Results show that both the elastic modulus and peak stress of sandstone decrease appreciably with water content increasing, but the internal friction angle is independent of the water content. The reduction in compressive strength is mainly attributed to the decrease of the material cohesion. The conclusions obtained in the study are of important value to estimate the wet strength of porous rocks in rock engineering.
Optical fiber hybrid-surface plasmon polaritons

When a thin metallic region exists between the core and the cladding regions of a step-index optical fiber, hybrid surface plasma modes can be supported. For each azimuthal mode order two hybrid modes generally occur. Their disperison and attenuation characteristics are studied. The selective influence of the core radius on these is found to be strong only if the radius is small. As the radius increases the modes become degenerate with those of the pure TM polarization.
Random walk models for top-N recommendation task

Recently there has been an increasing interest in applying random walk based methods to recommender systems. We employ a Gaussian random field to model the top-N recommendation task as a semi-supervised learning problem, taking into account the degree of each node on the user-item bipartite graph, and induce an effective absorbing random walk (ARW) algorithm for the top-N recommendation task. Our random walk approach directly generates the top-N recommendations for individuals, rather than predicting the ratings of the recommendations. Experimental results on the two real data sets show that our random walk algorithm significantly outperforms the state-of-the-art random walk based personalized ranking algorithm as well as the popular item-based collaborative filtering method.
A Noise Reduction Method Based on Linear Prediction Analysis

The linear prediction method works in such a way that the difference (prediction residual) between the objective signal and the output generated by making the objective signal a linear combination of the input signals is uncorrelated. Hence, in this linear prediction method, the linear predictor generates zero for the signal without correlation and recombines the voice for that with correlation. If this characteristic is used, recombined voice with suppressed noise can be obtained as the output of the linear predictor for voice with superposed white noise without correlation. Noise suppression can be realized by using this characteristic of the linear predictor. In this paper, a noise suppression method based on this linear prediction is discussed. According to this method, a noise suppression method without process delay can be realized. Also, no a priori information on the power spectrum of the noise is needed in this method. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(3): 1–10, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10056
Overview of the Atomistic Modeling of the Chemical Erosion of Carbon

Understanding the mechanisms of the chemical erosion of carbon by hydrogen is of great importance for the application and development of plasma-facing materials, as well as the macroscopic scale modeling of plasma-surface interactions in fusion devices. In the recent years there has been a number of atomistic modeling studies, namely molecular dynamics and electronic structure calculations, on these processes. This article is an overview of these investigations, with comparison to experimental measurements as well as current theoretical understanding of the chemical erosion of carbon. Implications of the modeling are discussed along with an outlook on future studies.
On the Borda-Kendall Consensus Method for Priority Ranking Problems

This paper investigates the Borda-Kendall method for the determination of a consensus ranking. It is shown that in the case of ties the method does not perform as claimed. A "minimum variance" method for determining the consensus ranking is proposed and its properties examined. It is shown to be equivalent to the Borda-Kendall method if ties are not allowed. An algorithm to determine the "minimum variance" consensus ranking in the case of ties is described. Results obtained from the solution of problems of various sizes are discussed.
Konrad-zuse-zentrum F ¨ Ur Informationstechnik Berlin Adaptive Finite Element Simulation of Ventricular Fibrillation Dynamics Adaptive Finite Element Simulation of Ventricular Fibrillation Dynamics

The dynamics of ventricular fibrillation caused by irregular excitation is simulated in the frame of the monodomain model with an action potential model due to Aliev-Panfilov for a human 3D geometry. The numerical solution of this multiscale reaction-diffusion problem is attacked by algorithms which are fully adaptive in both space and time (code library KARDOS). The obtained results clearly demonstrate an accurate resolution of the cardiac potential during the excitation and the plateau phases (in the regular cycle) as well as after a reentrant excitation (in the irregular cycle).
Spectral-signature-preserving compression of multispectral data

An enhancement to a previously developed Karhunen- Loeve/discrete cosine transform-based multispectral bandwidth compression technique is presented. This enhancement is achieved via addition of a spectral screening module prior to the spectral decorrelation process. The objective of the spectral screening module is to identify a set of unique spectral signatures in a block of multispectral data to be used in the subsequent spectral decorrelation module. The number of unique signatures found will depend on the desired spectral angle separation, irrespective of their frequency of occurrence. This set of unique spectral signatures, instead of the signature of each and every point of the block of data, will be used to construct the spectral covariance matrix and the resulting Karhunen-Loeve spectral transformation matrix that is used to spectrally decorrelate the multispectral images. The significance of this modification is that the covariance matrix so constructed will not be entirely based on the statistical significance of the individual spectral in the block but rather on the uniqueness of the individual spectra. Without this added spectral screening feature, small objects and ground features would likely be manifested in the low eigen planes mixed with all of the noise present in the scene. Since these lower eigen planes are coded via the subsequent JPEG compression module at a much lower bit rate, the fidelity of these small objects will be severely impacted by the compression-induced error. However, the addition of the proposed spectral screening module will relegate these small objects into the higher eigen planes and hence will greatly enhance preservation of their fidelities in the compression process. This modification alleviates the need to update the covariance matrix frequently over small sub-blocks, resulting in a reduced overhead bit requirement and a much simpler implementation task.
The physical nature of the short-period RS CVn system DV psc

We present multicolour CCD photometry of the short-period RS CVn-type binary DV Psc obtained in 2006 September and October. Our observations indicate that GSC0008-789, the comparison star used by Robb et al. in their discovery of DV Psc, is a variable with amplitude exceeding 0.08 mag. Based on the new data, the orbital period of the eclipsing system is revised to 0.308 53609 d. From the new observations, a set of completely covered B, V and R light curves and a single V-band light curve are formed in two epochs. The radial-velocity curves obtained by Lu, Rucinski & Ogloza are reformed with the newly determined ephemeris and are analysed along with the light curves using the 2003 version of the Wilson-Devinney code. The results show that DV Psc is a detached, near-contact binary system with a mass ratio of 0.693 ± 0.005 and a separation of 2.038 R ⊙ . The masses and radii for the components are determined as 0.70 ± 0.02 M ⊙ , 0.68 ± 0.03 R ⊙ for the primary, and 0.49 ± 0.01M ⊙ , 0.51 ± 0.02 R ⊙ for the secondary.
Discretized and Interpolated Kernel Density Estimates

Abstract The kernel estimate of a probability density function inherits its smoothness properties from the kernel density chosen by the investigator. Nevertheless, for computational (and especially graphical) reasons, exact kernel density estimates are often presented in (piecewise constant) discretized or (piecewise linear) interpolated form, using the exact estimate only at some grid of points. The asymptotic integrated mean squared error properties of these modifications are studied. It is seen that discretization may adversely affect the order of magnitude of this risk criterion, so care needs to be taken in practice to limit the degree of discretization employed. This roughness effect essentially disappears when interpolation is used instead; then, it takes a remarkably coarse grid to result in more than a negligible deterioration in the estimate's performance. Data discretization prior to applying the kernel density estimation prescription is also addressed. Such prebinning does not affect the smoot.
ENERGY AND EXERGY ANALYSIS OF AN AUTOMOTIVE DIRECT INJECTION DIESEL ENGINE

The article presents a 0D model development of the heat exchanger intended for a Rankine-Hirn cycle waste heat recovery system in internal combustion engines. The heat transfer in the exchanger was estimated as the volume was separated by small elements. For each of the elements the heat transfer was calculated depends on the temperature variation, surface of the transfer and total heat transfer coefficient. An estimation code based on the model was developed in Python. CoolProp simulation code was used for working fluid parameters determination. Numerical estimation of the heat transfer was presented with different working fluids at the most commonly used operating point of a tractor engine. Finally, a study of the working fluid mass flow rate effect on heat transfer effectiveness was conducted as water was used into the Rankine-Hirn cycle
Convective Mixing and Reactive Precipitation of Barium Sulfate in Microchannels

Reactive precipitation in micro- and minichannels currently draws attention of both chemists and engineers in the field of micro-process engineering. Due to intensified mixing and improved heat and mass transfer, fast chemical and thermodynamical processes involved in precipitation can be controlled readily in micro- or mini-structures. In particular, microchannels are a promising technology for particulate processes, allowing the continuous operation along with little or no backmixing. However, the sensitivity of microscale channels to blocking and fouling requires careful design and appropriate peripheral equipment. This study presents experimental results of barium sulfate precipitation from barium chloride solution and sulfuric acid in both T-shaped and injection micromixers. The measured particle size distributions (PSD) are characterized by their first and second moment, reflecting the correlation between fluidic mixing and precipitation: faster mixing results in smaller mean particle sizes (first moment of the PSD). The homogeneity of the mixing process on the other hand should have impact onto the width of the distribution (second moment of the PSD) due to the superposition of locally formed particles to the global size distribution. The experimental particle size distributions are compared with simulations based on reduced-order modeling of the diffusive mixing process, coupled with the population balance for particle nucleation and growth. While the simulated size distributions have mean diameters between 40 nm and 68 nm, experimental data are between 90 nm and 130 nm.