Miracle-dz/UniFAR-FTUs huggingface dataset:
Computation of power system low-order models from time domain simulations using a Hankel matrix

This paper describes an algorithm to calculate low-order linear models of power systems from small-signal time-domain simulation data. The linear system models preserve the modal characteristics of the underlying power system. The method is based on the computation of a real symmetric matrix and is well suited for the analysis of large data sets. The results presented in the paper include the computation of a transfer function suitable for power system stabilizer design and the synthesis of an equivalent linear system from a three-phase power system model.
Toward a nonperturbative topological string

We discuss three examples of nonperturbative phenomena in the topological string. First, we consider the computation of amplitudes in N = 4 super Yang-Mills theory using the B model topological string as proposed by Witten. We give an argument suggesting that the computations using connected or disconnected D-instantons of the B model are in fact equivalent. Second, we formulate a conjecture that the squared modulus of the open topological string partition function can be defined nonperturbatively as the partition function of a mixed ensemble of BPS states in d = 4. This conjecture is an extension of a recent proposal for the closed topological string. In a particular example involving a non-compact Calabi-Yau threefold, we show that the conjecture passes some basic checks, and that the square of the open topological string amplitude has a natural interpretation in terms of 2-dimensional Yang-Mills theory, again generalizing known results for the closed string case. Third, we discuss an action for an abelian two-form gauge theory introduced by Hitchin which describes variations of G2 structures in seven dimensions. Upon reducing to six dimensions this action splits into two pieces, one related to the complex structure and one related to the symplectic structure; we argue that these two pieces are related to the A and B model topological string theories. In this sense Hitchin’s gauge theory
N‐person games in partition function form

This paper gives a formulation of a theory of n‐person cooperative games with side payments in terms of a partition function which is defined on the set of all partitions of the set of players. The results for all games with n ≤ 3 are presented. This development generalizes the von Neumann‐Morgenstern theory of games in characteristic function form.
FINDING NATURAL CLUSTERS

On being presented with a set of points plotted on a plane space, most observers will agree that the set contains clusters of points if the distribution of the points meets certain conditions. We postulate that these conditions are: (1) that there are continuous, relatively densely populated regions of the space, and (2) that these are surrounded by continuous, relatively empty regions of the space. Using this definition for natural clusters we developed an algorithm for finding such clusters from the relative interpoint distances within a set. Starting with the closest pair of points, additional cluster members are sought by a minimum stepping stone strategy and accepted or rejected on the basis of parameters which indicate a discontinuity of closeness (i.e. a continuous, relatively empty space surrounding the points already admitted to the cluster). The procedure is repeated at a number of levels of resolution to give an overall view of the population. The resolution levels appropriate for a given set of points are determined from an analysis of the interpoint distances. Since the procedure uses only the relative distances between the points, it can be applied to points specified in any number of dimensions. "Classification, in its widest sense, has to do with forms of relatedness and with the organization and display of the relations in a useful manner" (Lynch, 1966). The general availability of computers has resulted in vigorous activity in both theoretical and practical aspects of classification, particularly among information specialists, mathematical psychologists, and numerical taxonomists. One aspect of this activity has been the examination of the way people classify things intuitively, so that the results can be duplicated or extended by computer programs.
Boundary element‐free method (BEFM) and its application to two‐dimensional elasticity problems

In this study, we first discuss the moving least‐square approximation (MLS) method. In some cases, the MLS may form an ill‐conditioned system of equations so that the solution cannot be correctly obtained. Hence, in this paper, we propose an improved moving least‐square approximation (IMLS) method. In the IMLS method, the orthogonal function system with a weight function is used as the basis function. The IMLS has higher computational efficiency and precision than the MLS, and will not lead to an ill‐conditioned system of equations. Combining the boundary integral equation (BIE) method and the IMLS approximation method, a direct meshless BIE method, the boundary element‐free method (BEFM), for two‐dimensional elasticity is presented. Compared to other meshless BIE methods, BEFM is a direct numerical method in which the basic unknown quantity is the real solution of the nodal variables, and the boundary conditions can be applied easily; hence, it has higher computational precision. For demonstration purpose, selected numerical examples are given. Copyright © 2005 John Wiley & Sons, Ltd.
Conceptual Model of Responses of Organisms, Populations and Ecosystems to all Possible Dose Rates of Ionising Radiation in the Environment

Some quantitative data on dose-effect or dose rate-effect relationships under conditions of chronic irradiation have been obtained in different investigations. A conceptual model of the biological responses to all magnitudes of dose rates of ionising radiation in nature, has been proposed and developed by the author, and considers the following zones: (I) zone of biological uncertainty-below the natural background from cosmic rays (under shields); (2) zone of well-being-at the level of the natural background; (3) zone of physiological masking-the appearance of biochemical, cytogenetic and physiological effects under higher dose rates is comparable with, and overlaps, the corresponding effects produced by natural radiation in the environments (4) zone of ecological masking - detectable effects in individual organisms are masked and eliminated at the level of the population and community; and (5) zone of damage to population and communities with dramatic and catastrophic consequences to ecosystems. This conceptual model covers quantitative investigations in oceanic, fresh water and terrestrial environments.
Boundary element analysis of nonlinear water wave problems

A new boundary element technique based on Green's formula is applied to the analysis of nonlinear water wave problems. The problems are formulated mathematically as two-dimensional nonlinear initial-boundary value problems in terms of a velocity potential, assuming the fluid to be inviscid and incompressible, and the flow to be irrotational. In the present paper, two kinds of wave-making problems are analysed: (1) a tsunami generated by sea bed elevation; (2) generation, propagation and run-up on a vertical wall of a solitary wave. Numerical results obtained by the present method are compared with available experimental data and analytical solutions. Excellent agreements are obtained.
A cluster based approach to robust regression and outlier detection

We consider the simultaneous estimation of the inlier set and the regression parameter using the contaminated data set, A, which has many members obey the linear model, but some do not. The single link clustering algorithm is used to partition the data set into inlier and outlier subsets. The subset having the least mean sum of squares of residuals is chosen to be the best subset among all subsets of A for a fixed link distance, /spl lambda/. By assuming that the outliers also obey the same type of density as the inliers but different parameters, we develop a negative log likelihood expression for all the observations in terms of /spl lambda/. By minimizing the negative log likelihood function with respect to /spl lambda/ we get the required /spl lambda/* and the regression parameters. We apply the theory developed here to two data sets, and show our method correctly estimates the regression parameters and the inlier set for the given data set. <<ETX>>
Studies of Highly Polar Atomic and Molecular Systems: Quantum Dynamics and the Route to Experimental Investigations

Theoretical investigation of the dynamics of adiabatic quantum mechanics in two different, highly polar systems has been made. The systems were chosen for their fundamental scientific interest, as they represent atoms and molecules with exaggerated properties, as well as ease of experimental study as such highly polar systems are easier to manipulate using readily-available electric fields. A model two-level system is used to derive one approach for maximizing the probability of adiabatic passage through an avoided crossing and this is compared with the classic Landau-Zener result, and the commonly encountered spin-flip problem of a particle with spin located in a rotating magnetic field. This approach is applied to the avoided crossing between the n = 13, n1 − n2 = 11 (dipole moment of 532 D) and the n = 14, n1 − n2 = −12 (dipole moment of -657 D) highly polar Stark states of the lithium atom at 447 kV/m. Ion-pair formation from two neutral lithium atoms, one in the 2s ground state and the other in an excited state, is also investigated. The cross section σ(v) for free ion-pairs is calculated for the initial colliding pairs of atomic states located below the ion-pair threshold. Li(2s) + Li(3d) is seen to possess the largest cross section (σ(v0) = 569.2 a.u. ) at its threshold velocity. The implications of this for bound ion-pair, i.e. heavy Rydberg system, production are briefly discussed. Furthermore, experimental progress towards the production of these atomic and molecular systems from a beam of lithium is presented.
Origin of forward leakage current in GaN-based light-emitting devices

The authors fabricated GaN-based light-emitting diodes (LEDs) on two different GaN templates with the same LED structure. One on thin GaN template (∼2μm) with high dislocation density [low (109cm−2)] grown by metal-organic vapor-phase epitaxy (sample A) and the other on thick GaN template (∼20μm) with comparatively low dislocation density [high (108cm−2)] by hydride vapor-phase epitaxy (sample B). In order to understand the mechanism of leakage current in LEDs, the correlation between current-voltage characteristics and etch pit density of LEDs was studied.
Naive control of the double integrator: a comparison of a dozen diverse controllers under off-nominal conditions

In naive control, a control algorithm derived under nominal, or ideal conditions is evaluated by analytical or numerical means under off-nominal, or non-ideal conditions that were not assumed in the formal synthesis procedure. Under such non-ideal conditions, the controller may or may not perform well. We consider an eclectic set of algorithms, ranging from classical to nonlinear and adaptive. Since the controllers are tuned by means of different procedures and since each controller has different capabilities, it is challenging to construct criteria that provide a useful evaluation of controller capabilities. Our approach to this problem is as follows. First, we specify nominal conditions in which the mass is given, and we tune each controller to minimize the worst case time to the origin from initial conditions located on the unit circle in the position/velocity phase plane without exceeding a peak input of unity. Next, we test each nominally tuned controller under a sequence of off nominal conditions.
The application of symplectic geometry on nonlinear dynamics analysis of the experimental data

For nonlinear dynamic analysis of the experiment data, one often uses SVD decomposition to reconstruct embedding dimension of attractor because of its simpleness. However, it is hardly for singular value decomposition (SVD) decomposition to get good results in the attractor reconstruction of the experiment data. For this, symplectic geometry method is proposed to estimate embedding dimension of reconstruction attractor in this paper. We illustrate the feasibility of this method and give the embedding dimension of the action surface EMG signal.
Surveying the MeV gamma-ray sky with AMEGO-X

Recent detections of gravitational wave signals and neutrinos from gamma-ray sources have ushered in the era of multi-messenger astronomy, while highlighting the importance of gamma-ray observations for this emerging field. AMEGO-X, the All-sky Medium Energy Gamma-Ray Observatory eXplorer, is an MeV gamma-ray instrument proposed to the 2021 call for medium-sized explorer missions. AMEGO-X will survey the sky in the energy range from 100 keV to 1 GeV with unprecedented sensitivity, as well as detecting and localizing transient events such as gamma-ray bursts and magnetar activity down to 25 keV. AMEGO-X will detect gamma-ray photons both via Compton interactions and pair production processes, bridging the “sensitivity gap” between hard X-rays and high-energy gamma rays. AMEGO-X will provide important contributions to multi-messenger science and time-domain gamma-ray astronomy, studying e.g. high-redshift blazars, which are probable sources of astrophysical neutrinos, and gamma-ray bursts. I will present an overview of the instrument and anticipated science program.
Evaluation of FLIR/IR camera technology for airport surface surveillance

The Federal Aviation Administration (FAA) is evaluating Forward Looking Infrared (FLIR) and IR focal plane array technology as part of the Airport Surface Traffic Automation program. Under this program a new application for these technologies in aviation will be developed. The goal of the program is to evaluate FLIR and IR cameras for enhanced Air Traffic Control surface surveillance in all weather conditions for some major airports. Initially, FLIR cameras will be installed at airports with varying traffic densities to analyze and compare their capabilities along with other IR camera systems, displays and security/surveillance software. These cameras will be evaluated for both technical and operational performance. This paper discusses the initial studies that demonstrated the usefulness of FLIR technology for search and rescue situations and multiple coverage for integration with automatic surveillance systems. The general operation of the three IR camera systems to be evaluated in this study is presented. Finally, a concept for the possible integration of FLIR and IR technology with current automatic surface surveillance systems under development such as the Airport Movement Area Safety System and the Airport Traffic Identification System programs is proposed. This paper will conclude with a review of the FAA's future plans for evaluating a microbolometer based, uncooled IR camera system.
The influence of electrodes thicknesses on the characteristics of a helium plasma jet

An atmospheric plasma jet reactor (PJR) was designed using two outer disc-like copper plats placed around a quartz tube. The effects of the electrodes’ thicknesses and their placement on the plasma jet length created in helium and its electrical characteristics were investigated. Measurements of the plasma jet length were carried out for different applied voltages and different gas flow rates. The electrical characteristics (such as discharge current and power consumption) of the plasma jet obtained using a high voltage generator delivering a sin-wave signal varying from 13kVp-p to 17kVp-p at a resonance frequency of 5.5kHz, were measured/calculated. The best results (long plasma plume and intense plasma) were obtained with a reactor equipped with a thicker upper electrode and a thinner lower electrode. Using this configuration, a plasma plume 55mm long was reached at 17kVp-p and 7slm of helium.
Vector Magnetic Field Sensing at Tiny Angles Through a Nanofluid Functionalized Ultrathin Taper Interferometer

Aiming at the requirement of high precision and long life in tasks of mechanical and navigation industries, a highly sensitive and compact, magnetorheological fluid film-suspended nonadiabatic biconical tapered optical fiber interferometer-based vector magnetometer has been proposed and demonstrated in the manuscript. The reported magnetometer keeps the ability to detect the strength of the magnetic field and its direction in the 3D plane concurrently. Magnetically regulated effective index amendment is used to stimulate the higher order modes propagating in the cladding region of the ultrathin biconical fiber interferometer. Hence, the detection principle of the sensor depends on the changes in the effective indices of higher-order excited modes with respect to the applied magnetic field. The proposed magnetometer detects slight angular variations of -2° to +2° in the magnetic field over a broad range from 0 mT to 567 mT by using the azimuth-dependent anisotropic distribution of nanoparticles in the vicinity of the fiber-optic sensor arm. The reported sensor offers to its angular sensitivities of ~ ∓14.68 pm/mT, and ~ ∓11.79 pm/mT at minor inclinations of ∓1° and ∓2° whereas having its maximum sensitivity of ~ 16.48 pm/mT at 0°.
Turbulent boundary layers subjected to multiple curvatures and pressure gradients

The effects of abruptly applied cycles of curvatures and pressure gradients on turbulent boundary layers are examined experimentally. Two two-dimensional curved test surfaces are considered: one has a sequence of concave and convex longitudinal surface curvatures and the other has a sequence of convex and concave curvatures. The choice of the curvature sequences were motivated by a desire to study the asymmetric response of turbulent boundary layers to convex and concave curvatures. The relaxation of a boundary layer from the effects of these two opposite sequences has been compared. The effect of the accompanying sequences of pressure gradient has also been examined but the effect of curvature dominates. The growth of internal layers at the curvature junctions have been studied. Measurements of the Górtler and corner vortex systems have been made. The boundary layer recovering from the sequence of concave to convex curvature has a sustained lower skin friction level than in that recovering from the sequence of convex to concave curvature. The amplification and suppression of turbulence due to the curvature sequences have also been studied.
Parental education and income are linked to offspring cortical brain structure and psychopathology at 9–11 years

A childs socioeconomic environment can shape central aspects of their life, including vulnerability to mental disorders. Negative environmental influences in youth may interfere with the extensive and dynamic brain development occurring at this time. Indeed, there are numerous yet diverging reports of associations between parental socioeconomic status (SES) and child cortical brain morphometry. Most of these studies have used single metric- or unimodal analyses that downplay the probable scenario that separate sources of variability, from numerous independent biological pathways, are the basis for SES-related cortical differences in youth. To comprehensively capture such variability, using data from 9758 children aged 8.9-11.1 years from the ABCD Study, we employed linked independent component analysis (LICA) and fused vertex-wise cortical thickness, surface area, curvature and grey-/white-matter contrast (GWC). LICA revealed 70 uni- and multimodal components. We then assessed the linear relationships between parental education, parental income and each of the cortical components, controlling for age, sex, genetic ancestry, and family relatedness. We also assessed whether cortical structure moderated the negative relationships between parental SES and child general psychopathology. Parental education and income were both associated with larger surface area and higher GWC globally, in addition to local increases in surface area and to a lesser extent bidirectional GWC and cortical thickness patterns. The negative relation between parental income and child psychopathology were attenuated in children with a multimodal pattern of larger frontal- and smaller occipital surface area, and lower medial occipital thickness and GWC. In conclusion, structural brain MRI is sensitive to SES-related variability in childhood, and in low-income families, having a more developed cortex across MRI metrics, is beneficial for mental health.
A fast search algorithm for vector quantization using wavelet transform

A new fast codeword search algorithm for vector quantizers (VQ) is presented in this paper. This algorithm uses the pyramid structure of the codewords to accelerate the encoding process. The pyramid structure is obtained using the wavelet transform. This algorithm is able to reduce the codeword search time without sacrificing the performance and storage complexity of the VQ. Simulation results show that this algorithm is well-suited for the VQ with high vector dimension.
Plasmodium ARK2-EB1 axis drives the unconventional spindle dynamics, scaffold formation and chromosome segregation of sexual transmission stages

Mechanisms of cell division are remarkably diverse, suggesting the underlying molecular networks among eukaryotes differ extensively. The Aurora family of kinases orchestrates the process of chromosome segregation and cytokinesis during cell division through precise spatiotemporal regulation of their catalytic activities by distinct scaffolds. Plasmodium spp. , the causative agents of malaria, are unicellular eukaryotes that have three divergent aurora-related kinases (ARKs) and lack most canonical scaffolds/activators. The parasite uses unconventional modes of chromosome segregation during endomitosis and meiosis in sexual transmission stages within mosquito host. This includes a rapid threefold genome replication from 1N to 8N with successive cycles of closed mitosis, spindle formation and chromosome segregation within eight minutes (termed male gametogony). Kinome studies had previously suggested likely essential functions for all three Plasmodium ARKs during asexual mitotic cycles; however, little is known about their location, function, or their scaffolding molecules during unconventional sexual proliferative stages. Using a combination of super-resolution microscopy, mass spectrometry, and live-cell fluorescence imaging, we set out to investigate the role of the atypical Aurora paralog ARK2 to proliferative sexual stages using rodent malaria model Plasmodium berghei. We find that ARK2 primarily localises to the spindle apparatus in the vicinity of kinetochores during both mitosis and meiosis. Interactomics and co-localisation studies reveal a unique ARK2 scaffold at the spindle including the microtubule plus end-binding protein EB1, lacking conserved Aurora scaffold proteins. Gene function studies indicate complementary functions of ARK2 and EB1 in driving endomitotic divisions and thereby parasite transmission. Our discovery of a novel Aurora kinase spindle scaffold underlines the emerging flexibility of molecular networks to rewire and drive unconventional mechanisms of chromosome segregation in the malaria parasite Plasmodium.