Miracle-dz/UniFAR-FTUs huggingface dataset:
Conformal compactification of spacetimes

The conformal groups for the nine two-dimensional real spaces of constant curvature are realized as matrix groups acting as globally defined linear transformations in a four-dimensional ‘conformal ambient space’. This affords a unified and global study of the ‘conformal completion’ or compactification for the three classical Riemannian spaces as well as of the six relativistic and non-relativistic spacetimes (Minkowskian, de Sitter, anti-de Sitter, both Newton–Hooke and Galilean). The conformal embedding of the initial space into its compactification is carried out explicitly through two methods: either a group-theoretical one involving one-parameter subgroups or a geometric one by means of a stereographic projection. In the Euclidean and Minkowskian spaces the results reduce to the well known ones, but in the generic situation, with any non-zero curvature or arbitrary type signature, the approach is very explicit and provides some new insights.
A vectorized systolic array for parallel weight extraction of block RLS

A new vectorized systolic array for extracting weight coefficients in block RLS is proposed. Our array is based on a generalization of the inverse factorization method of Pan and Plemmons and the array for computing residual vectors in block RLS using the Householder transformation of Liu et al. the new array is obtained by first generalizing the inverse factorizations for the block case and then deriving a formula for updating the tap coefficients without matrix operations.
Precision measurement of the oscillator strength of the cesium-6 S-2(1/2)-> 5 D-2(5/2) electric quadrupole transition in propagating and evanescent wave fields

Hyperfine-structure-resolved absorption spectra of the 6 {sup 2}S{sub 1/2}{yields}5 {sup 2}D{sub 5/2} of cesium atoms have been observed with a temperature-controlled cell and a diode laser. From a comparison with the absorption of the D{sub 2} transition at the same atom density range, the oscillator strength of the electric quadrupole transition was determined to be (4.69{+-}0.05)x10{sup -7}. Reflection spectra of the same transition have also been observed in the partial and total reflection regimes with a reflection cell. An increase in the apparent oscillator strength was observed for total reflection with an increase in the angle of incidence, by a factor up to 1.5 at {theta}{sub c}+83.8 mrad and 2.4 at {theta}{sub c}+107.5 mrad for s and p polarizations, respectively, where {theta}{sub c} is the critical angle. The observed enhancement is ascribed to the incidence-angle-dependent wave vector and polarization vector of the evanescent wave.
A cyclotron‐maser instability associated with a nongyrotropic distribution

A stability analysis for the cyclotron‐maser instability in the presence of a nongyrotropic electron distribution is presented. The model configuration describes a uniformly magnetized cold ambient plasma that contains a relatively diffuse suprathermal electron component coherently bunched in gyrophase. The stability of perturbations propagating parallel to the ambient magnetic field is considered, and substantial growth rates are found to occur. The results are contrasted with those found for a comparable gyrotropic loss‐cone distribution, and it is found that the nongyrotropic instability is characterized by substantially higher growth rates.
Predictable Components and Singular Vectors

Abstract This paper shows that if a measure of predictability is invariant to affine transformations and monotonically related to forecast uncertainty, then the component that maximizes this measure for normally distributed variables is independent of the detailed form of the measure. This result explains why different measures of predictability such as anomaly correlation, signal-to-noise ratio, predictive information, and the Mahalanobis error are each maximized by the same components. These components can be determined by applying principal component analysis to a transformed forecast ensemble, a procedure called predictable component analysis (PrCA). The resulting vectors define a complete set of components that can be ordered such that the first maximizes predictability, the second maximizes predictability subject to being uncorrelated of the first, and so on. The transformation in question, called the whitening transformation, can be interpreted as changing the norm in principal component analysis.
Schrödinger Basis for Spinor Representations of the Three‐Dimensional Rotation Group

It is shown that the double‐valued spherical harmonics provide a basis for the irreducible spinor representations of the three‐dimensional rotation group. Pauli's assertion to the contrary is shown to be false. Both infinitesimal and finite rotations are discussed in some detail. It is also shown that there remains a twofold degeneracy in the spherical harmonic Yim when j and m are specified.
SUPERQUADRICS AND MODAL DYNAMICS FOR DISCRETE ELEMENTS IN INTERACTIVE DESIGN

This paper discusses advances in interactive discrete element simulation for use in computer‐aided concurrent design. We highlight the computational problems of creating a ‘virtual world’ populated by objects which behave much as real world objects and propose a system based on a new class of volumetric models, called superquadrics. These functions have significant advantages for calculating multibody interactions, and by coupling volumetric representation to a modal decomposition method for the physical dynamics we have been able to gain up to two orders of magnitude in efficiency. The modal method allows us to trade off high order modes for improved stability, time step magnitude, temporal aliasing and speed of response, and so provide almost real time feedback to the designer. We believe that virtual manufacturing systems will be especially useful in conceptual design, in design for manufacture and in the new thrust in concurrent design.
Techniques for developing land-use classification using moderate resolution imaging spectroradiometer imagery

Abstract. Using NOAA AVHRR or MODIS imagery to create land-use classifications has been attempted for many years. Unfortunately, most of these classifications do not differentiate crop types. Crop models require that vegetation characteristics extracted from an image be the correct crop type. This study compares four techniques to create land-use classifications using MODIS data. These classifications were compared to the ground data that had been set aside, to a mask where each MODIS sized pixel were at least 80% of a single land-used based on a Landsat TM classification for the same year, and to the Landsat TM classification. Using a decision tree method and comparing the classification to an 80% mask resulted in an accuracy of 73% which was the highest accuracy obtained in this study. The study showed that accuracies could range from 37% to 73% depending on the classification process and if segment data, an 80% mask, or a Landsat TM classification were used for accuracy assessment.
A GENERAL MULTIPLE-RELAXATION-TIME BOLTZMANN COLLISION MODEL

We formulate a simple extension to the Bhatnagar-Gross-Krook collision model by expanding the distribution function in Hermite polynomials and assigning a relaxation time to each hydrodynamic moment. By discretizing the velocity space, multiple-relaxation-time lattice Boltzmann models can be constructed. The transport coefficients are analytically calculated and numerically verified. At the lowest order, allowing different relaxation rates for the second and third Hermite components results in a variable Prandtl number. Comparing with the previously proposed multiple-relaxation-time lattice Boltzmann models, the present formulation is general in the sense that it is independent of the underlying lattice structure and does not require a procedure for transformation of base vectors.
A study of the predictability of a 28-variable atmospheric model

A 28-variable model of the atmosphere is constructed by expanding the equations of a two-level geostrophic model in truncated double-Fourier series. The model includes the nonlinear interactions among disturbances of three different wave lengths. Nonperiodic time-dependent solutions are determined by numerical integration. By comparing separate solutions with slightly different initial conditions, the growth rate of small initial errors is studied. The time required for errors comparable to observational errors in the atmosphere to grow to intolerable errors is strongly dependent upon the current circulation pattern, and varies from a few days to a few weeks. Some statistical predictability of certain quantities seems to be present even after errors in the complete circulation pattern are no longer small. The feasibility of performing similar studies with much larger atmospheric models is considered. DOI: 10.1111/j.2153-3490.1965. tb01424.x
Binary star science with interferometry

The development of optical interferometry will literally open a new dimension in the study of binary stars. As a prelude to the session, this paper reviews those properties of stars in binary systems that are of greatest scientific interest and summarizes what has been learned with the traditional tools of photometry and spectroscopy. We then discuss the information provided by interferometry and how it is most powerfully exploited in combination with other, complementary tools. This is illustrated by a few recent cases in which optical interferometry has helped to break new ground in ways that point towards the future. Finally, some recommended procedures are listed which may help to optimize the scientific returns of interferometric studies of binary stars.
High dynamic range algorithm based on HSI color space

This paper presents a High Dynamic Range algorithm based on HSI color space. To keep hue and saturation of original image and conform to human eye vision effect is the first problem, convert the input image data to HSI color space which include intensity dimensionality. To raise the speed of the algorithm is the second problem, use integral image figure out the average of every pixel intensity value under a certain scale, as local intensity component of the image, and figure out detail intensity component. To adjust the overall image intensity is the third problem, we can get an S type curve according to the original image information, adjust the local intensity component according to the S type curve. To enhance detail information is the fourth problem, adjust the detail intensity component according to the curve designed in advance. The weighted sum of local intensity component after adjusted and detail intensity component after adjusted is final intensity. Converting synthetic intensity and other two dimensionality to output color space can get final processed image.
Triply differential single ionization cross sections in coplanar and non-coplanar geometry for fast heavy ion-atom collisions

We have performed a kinematically complete experiment and calculations on single ionization in 100 MeV/amu C6+ + He collisions. For electrons ejected into the scattering plane (defined by the initial and final projectile momentum vectors) our first- and higher-order calculations are in good agreement with the data. In the plane perpendicular to the scattering plane and containing the initial projectile axis a strong forward-backward asymmetry is observed. In this plane both the first-order and the higher-order calculations do not provide good agreement neither with the data nor amongst each other.
Advances in the Echidna fiber-positioning technology

We present advances in the patented Echidna 'tilting spine' fiber positioner technology that has been in operation since 2007 on the SUBARU telescope in the FMOS system. The new Echidna technology is proposed to be implemented on two large fiber surveys: the Dark Energy Spectroscopic Instrument (DESI) (5000 fibers) as well the Australian ESO Positioner (AESOP) for 4MOST, a spectroscopic survey instrument for the VISTA telescope (~2500 fibers). The new 'superspine' actuators are stiffer, longer and more accurate than their predecessors. They have been prototyped at AAO, demonstrating reconfiguration times of ~15s for errors of <5 microns RMS. Laboratory testing of the prortotype shows accurate operation at temperatures of -10 to +30C, with an average heat output of 200 microwatts per actuator during reconfiguration. Throughput comparisons to other positioner types are presented, and we find that losses due to tilt will in general be outweighed by increased allocation yield and reduced fiber stress FRD. The losses from spine tilt are compensated by the gain in allocation yield coming from the greater patrol area, and quantified elsewhere in these proceedings. For typical tilts, f-ratios and collimator overspeeds, Echidna offers a clear efficiency gain versus current r-that or theta-phi positioners.
Generation of calcium waves in living cells by pulsed-laser-induced photodisruption

Here, we present an optical technique that can induce waves of calcium ion concentration in live biological cells. Ca2+ waves were induced by femtosecond pulsed-laser illumination. Living HeLa cells were exposed to focused 140 fs pulses of 780 nm wavelength at 30 mW average power. Ca2+ waves were imaged by fluorescence and were observed to propagate from the laser focal point inside the cell. Photoinduced generation of Ca2+ waves can be performed at any point inside the cell, an improvement over previous mechanical or biochemical stimulation techniques.
On a global estimate in a linear inverse hyperbolic problem

We show a global Lipschitz estimate in determining a source term in a hyperbolic equation from overdetermining data on the lateral boundary. The method is a combination of the uniqueness result by the Carleman estimate and the compactness - uniqueness argument, and is also widely applicable to the determination of source terms or coefficients in the general multidimensional case. Dedicated to Professor Takashi Kayano on his 63rd birthday
Indoor localization using passive RFID

Radio frequency identification (RFID) systems based on passive tags are used successfully in a wide range of object identification applications. However, the increasing needs to meet new demands on applications of localization and tracking create a new field for evolution of the RFID technology. This paper presents the design, implementation, and evaluation of a cost-effective localization system for in-building usage that is able to localize objects that carry passive RFID tags. The RFID reading is performed by a single Reader and an array of directional antennas through multiplexing. Evaluation and experimental results from three localization algorithms based on RSSI are presented.
A Monte Carlo Approach to Filtering for a Class of Marked Doubly Stochastic Poisson Processes

Marked doubly stochastic Poisson processes are a particular type of marked point processes that are characterized by the number of events in any time interval as being conditionally Poisson distributed, given another positive stochastic process called intensity. Here we consider a subclass of these processes in which the intensity is assumed to be a deterministic function of another nonexplosive marked point process. In particular, we will investigate an intensity jump process with an exponential decay having an analytic form for the distribution of the times and sizes of the jumps, which can be seen as a generalization of the classical shot noise process. Assuming that the intensity is unobservable, interest here is in its filtering, that is, in the computation of its conditional distribution, over a whole time interval, given an observed trajectory of realized events. Because, in general, this computation cannot be performed analytically, we propose a simulation method that provides an approximate solution, which relies on the reversible-jump Markov chain Monte Carlo algorithm. Interestingly, the proposed filtering algorithm also allows the setup of a likelihood-based procedure for the estimation of the parameters of the model based on stochastic versions of the expectation–maximization (EM) algorithm. The potential of the filtering and estimation methods proposed are illustrated through some simulation experiments as well as on a financial ultra-high-frequency dataset of intraday S&P500 futures prices.
Irreducibility and Galois Properties of Lifts of Supersingular Polynomials

It has recently been shown that a rational specialization of Jacobi polynomials, when reduced modulo a prime number p, has roots which coincide with the supersingular jinvariants of elliptic curves in characteristic p. These supersingular lifts are conjectured to be irreducible with maximal Galois groups. Using the theory of p-adic Newton Polygons, we provide a new infinite class of irreducibility and, assuming a conjecture of Hardy and Littlewood, give strong evidence for their Galois groups being as large as possible.
Supernova 1987K: Type II in Youth, Type Ib in Old Age

Spectra of SN 1987K in NGC 4651 have been obtained 0-2 weeks past maximum brightness and 5-7 weeks past maximum. The results suggest that SNe II and at least some SNe Ib are closely related objects, and that SN 1987A could have been a massive star which lost a majority of its hydrogen prior to exploding. It is proposed that SN 1987A belongs to a new subclass, type IIb, of SN that have the spectral characteristics of type II near maximum brightness and those of type Ib long past maximum. 64 references.
Quantitative analysis of Kerr nonlinearity and Kerr-like nonlinearity induced via terahertz generation in ZnTe

Kerr nonlinearity and Kerr-like nonlinearity induced via terahertz generation and the electro-optical effect in ZnTe crystal are investigated. In general, these nonlinear effects are concomitant and difficult to quantitatively analyze in the time domain. Even Z-scan technique, which is a simple and sensitive single-beam method to determine both the sign and magnitude of the nonlinear refractive index as well as the nonlinear absorption coefficient of a given material, cannot quantitatively analyze the contribution of each nonlinear effect directly. A method is proposed in the spectral domain to distinguish between Kerr nonlinearity and Kerr-like nonlinearity. Experimental results agree with theoretical analysis.
Time-resolved photon counting allows for new temporal and spatial insights into the nanoworld

The time-correlated single photon counting (TCSPC) technique combined with clock oscillator set by the pulsed laser provides a precise measurement of the arrival time of the detected photons with picosecond resolution for a time-scale of hours. If TCSPC is combined with other experimental techniques such as optical spectroscopy and mechanical manipulation, it is possible to coincide the detected fluorescence signal with the changes of the sample properties. High temporal resolution achieved in TCSPC (down to ps) allows us to monitor fast mechanical processes in single molecules. Here we present recent developments in fluorescence correlation spectroscopy (FCS) as well as the combination of TCSPC with optical scanning microscopy and mechanical manipulation by means of an atomic-force microscope (AFM).
Comparison of cone beam artifacts reduction: two pass algorithm vs TV-based CS algorithm

In a cone beam computed tomography (CBCT), the severity of the cone beam artifacts is increased as the cone angle increases. To reduce the cone beam artifacts, several modified FDK algorithms and compressed sensing based iterative algorithms have been proposed. In this paper, we used two pass algorithm and Gradient-Projection-Barzilai-Borwein (GPBB) algorithm to reduce the cone beam artifacts, and compared their performance using structural similarity (SSIM) index. In two pass algorithm, it is assumed that the cone beam artifacts are mainly caused by extreme-density(ED) objects, and therefore the algorithm reproduces the cone beam artifacts(i.e., error image) produced by ED objects, and then subtract it from the original image. GPBB algorithm is a compressed sensing based iterative algorithm which minimizes an energy function for calculating the gradient projection with the step size determined by the Barzilai- Borwein formulation, therefore it can estimate missing data caused by the cone beam artifacts. To evaluate the performance of two algorithms, we used testing objects consisting of 7 ellipsoids separated along the z direction and cone beam artifacts were generated using 30 degree cone angle. Even though the FDK algorithm produced severe cone beam artifacts with a large cone angle, two pass algorithm reduced the cone beam artifacts with small residual errors caused by inaccuracy of ED objects. In contrast, GPBB algorithm completely removed the cone beam artifacts and restored the original shape of the objects.
Vibration Control of Oscillating System Based on Governing Visco-Elastic Characteristics of Absorber by Means of External Electric Signal

Electro-rheological fluids (ERF) allow us to create «smart» devices. One of the basic directions of application of such materials is damping in oscillating systems. This work describes simulation model and offers the results of experimental research by rheological properties and damping characteristic of ERF. Control signal is defined by electric field intensity, which is changed within the bounds of 0…0.5 kV/mm. Amplitude of oscillation – up to 5 mm, oscillation frequency is modified within the bounds of 0.5…5 Hz. The logarithmic damping decrement and natural oscillation frequency of oscillating system, shear stress and viscosity of ERF are determined.
THE IONIZATION STRUCTURE OF HELIUM IN H II REGION COMPLEXES.

Ionization structure models of H II regions are constructed to analyze the behavior of the helium ionization correction factor, icf, for combinations of different stellar radiation fields as well as for mixtures of individual H II regions of different degrees of ionization. It is found that the amount of neutral He is less than 3 percent and that icf is between 0.98 and 1.00, for H II region coomplexes ionized by OB associations where the hottest stars are earlier than O6, if the ionizing stars are distributed according to a normal IMF. This result applies for a single H II region or for a mixture of unconnected H II regions. This result implies that the He(+)/H(+) ratio observed in extragalactic H II regions of high degree of ionization corresponds to the true He/H abundance ratios.
Dynamic Response of a Fibre Optic Ring Resonator with Sinusoidal Phase Modulation of the Loop

Abstract. We report an analysis of the dynamic response of a fibre optic ringresonator when the resonator loop is phase modulated sinusoidally . It is shownthat whenf,,,i, the product of the modulating frequency (fm)and loop delay time(r), becomes greater than certain value (in the range of 0 . 0004 to 0. 06 that dependson the finesse of the ring) the response of the FORR deviates from steady stateresponse. Experimental results are given to verify the theoretical analysis.1. IntroductionDue to the high phase sensitivity, fibre optic ring resonators (FORR) havereceived much attention for use in interferometric sensor applications [1]-[6]. Withthe use of a low insertion loss directional coupler and a high-quality low-loss singlemode fibre, an FORR with high finesse is ideal for nonlinear optics, e.g., a relativelylow-power laser could cause stimulated Brillouin oscillation [7]. In another report[8] the FORR has been used for measurement and stabilization of spectralcharacteristics of an external cavity laser diode . The characteristics of FORR havebeen described by several authors [9]-[11]. The published reports on performancecharacteristics of FORR mostly dealt with the steady state response of the deviceassuming the ring loop length to be constant whereas that may not be the case aspointed out by loannidis