Miracle-dz/UniFAR-FTUs huggingface dataset:
Necessary conditions for the N-representability of the second-order reduced density matrix: Upper bounds on the P and Q matrices

Usually, variational calculations for the second-order reduced density matrix are performed subject to the constraint that the 'P' and 'Q' matrices are positive semidefinite, which only constrains the lowest eigenvalue of these matrices. We characterize the highest eigenvalue of these matrices and discuss how the associated constraint (which is related to the ground-state energy of the Hamiltonians H=-P and H=-Q) can be implemented in practical calculations. This necessary condition for N-representability should help ensure that the second-order reduced density matrix is not 'overcorrelated'.
The Product-Limit Estimate as an Inverse-Probability-Weighted Average

Abstract For randomly censored data, (Satten, G. A., Datta S. (2001). The Kaplan–Meier estimator as an inverse-probability-of-censoring weighted average. Amer. Statist. Ass. 55:207–210) showed that the Kaplan–Meier estimator (product-limit estimator (PLE)) can be expressed as an inverse-probability-weighted average. In this article, we consider the other two PLEs: the truncation PLE and the censoring-truncation PLE. For the data subject to left-truncation or both left-truncation and right-censoring, it is shown that these two PLEs can be expressed as inverse-probability-weighted averages.
Inverse Scattering In The First Born Approximation

Wolf's formulation for inverse scattering in the first Born approximation is reviewed and discussed from an experimental point-of-view. Some of the experimental problems associated with obtaining enough data to satisfy the requirements of this theory are described and a method for using symmetry to reduce the data requirements for a class of scatterers is explained. A successful experiment which employed this theory to reconstruct structure in an object with rectangular structure is reviewed. It appears that this theory is extremely difficult to apply to a more general scatterer with no simplifying symmetries.
Text to speech—An overview

We discuss the design of a text‐to‐speech synthesizer, which accepts any type of English text as input, and creates an appropriate speech signal as output. Effective algorithms for converting text to sound must make use of intermediate data structures that systematically encode the degrees of freedom available to speakers of the language being synthesized. These data structures are an engineering approximation to what linguists call phonological representations; we will call them “P‐structures. ” Any TTS system must: (1) define its version of P‐structures; (2) design and implement algorithms for transforming input text into P‐structures; (3) design and implement algorithms for transforming P‐structures into sound. Task ♯1 is mainly a problem in applied linguistics; task ♯2 can best be seen as applied AI; task ♯3 is an application of phonetics and signal processing expertise. Because of the interdependence of approximate solutions in different portions of the system, integration of the various parts is a no.
Value iteration and rolling plans for Markov control processes with unbounded rewards

The authors study the convergence of value-iteration functions and the existence of error bounds for rolling horizon procedures in discrete-time Markov control processes with Borel state and control spaces, and unbounded reward functions with a discount factor. As expected, in contrast to the bounded case, the bounds are 'pointwise,' not 'uniform'. In addition, it is shown how the error bound in the weighted norm case can be improved by introducing appropriate ergodicity conditions. <<ETX>>
ON UNIQUENESS CLASSES FOR DEGENERATING PARABOLIC EQUATIONS

We study the uniqueness classes of a generalized solution of the Cauchy problem (1)when the matrix is degenerate. A generalized solution is introduced with the help of an infinitesimal operator of a Markov process connected with the operator in (1). In the proof of the theorems we use probabilistic characteristics of this process.Bibliography: 11 items.
Link power budget advantage in GI-core polymer optical waveguide link for optical printed circuit boards

For further advancement of next-generation high-performance computers, low-power consumption, high-density, and low-cost optical interconnection technologies should be adopted, and thus, optical printed circuit boards (O-PCBs) integrating polymer optical waveguides would be a key device. In particular, for low-power consumption, the link power budget should be low enough. In the optical link that consists of two waveguides on PCBs and a graded-index (GI) multimode fiber (MMF) connecting the two PCBs, such a low power budget is expected when GI-core waveguides are utilized. Essentially low coupling loss between the GI-core waveguide and a GI-MMF is one of the reasons of the low power budget, since the mode power profile mismatch between MMFs and GI-core waveguides is smaller than that between MMFs and SI-core waveguides. In this paper, we compose an optical link of vertical cavity surface emitting laser (VCSEL)-waveguide: SI or GI-MMF-waveguide: SI or GI-PD, and quantitatively evaluate the coupling loss at each connection point. When all the components are perfectly aligned, the total coupling loss is 1.9 dB in the link with GI-core waveguide. On the other hand, the SI-core waveguide link shows 0.8 dB higher coupling loss (2.72dB) than the GI-core waveguide link. When a misalignment of ±10 μm is added at each connection and 50-μm gaps are added at both VCSEL-waveguide and waveguide-PD connections, the GI-waveguide link demonstrate approximately 2-dB advantage in the power budget over the SI-waveguide link. Given limited power budget consideration for high bit rate optical links (~25 Gb/s), GI-core waveguide enabling low link power budget would be a promising component for O-PCBs.
Urban cloud condensation nuclei spectral flux

Abstract The cloud condensation nuclei (CCN) spectral flux and the condensation nuclei (CN) flux from an urban area are determined from in situ aircraft measurements at Denver, Colorado. The concentration differences between upwind and downwind cross sections at several altitudes are used to estimate anthropogenic fluxes. The CCN and CN production rate estimates are consistently three times larger than a similar 1966 study by Squires, also at Denver. On a per capita basis, the present measurements are only a factor of 2 higher. This is probably within the seasonal and day-to-day variability and/or may be result of somewhat different measurement techniques. The instantaneous CCN spectra produced flux estimates over the range of critical supersaturation Sc of 0.04%0.9%. Some of the estimated particle production rates for Denver are 1 × 1018 s−1 for CN, 1.7 × 1017 s−1 for CCN at 0.9% Sc, 1.16 × 1017 s−1 for CCN at 0.5% Sc, 3 × 1015 s−1 for CCN at 0.1% Sc, and 5 × 1014 s−1 for CCN at 0.04% Sc.
Reduced thermal quadrupole heat transport modeling in harmonic and transient regime scanning thermal microscopy using nanofabricated thermal probes

The thermal model of a nanofabricated thermal probe (NTP) used in scanning thermal microscopy is proposed. It is based on consideration of the heat exchange channels between electrically heated probe, a sample, and their surroundings, in transient and harmonic regimes. Three zones in the probe-sample system were distinguished and modeled by using electrical analogies of heat flow through a chain of quadrupoles built from thermal resistances and thermal capacitances. The analytical transfer functions for two- and three-cell quadrupoles are derived. A reduced thermal quadrupole with merged RC elements allows for thermo-electrical modeling of the complex architecture of a NTP, with a minimum of independent parameters (two resistance ratios and two time constants). The validity of the model is examined by comparing computed values of discrete RC elements with results of finite element simulations and with experimental data. It is proved that the model consisting of two or three-cell quadrupole is sufficient f.
Realistic listening improved by adding fine structure

Speech communication often takes place in noisy and reverberant environments. Unfortunately, cochlear implant (CI) users perform significantly poorer than normal hearing listeners under adverse conditions. We hypothesize that the noise susceptibility of CI users is largely due to the lack of encoding the fine structure cue. Most CI speech processing algorithms extract and encode the slowly varying amplitude modulation in speech (the envelope), while the rapidly varying fine structure is replaced with a fixed rate carrier. We have developed a new speech processing algorithm, called Frequency‐Amplitude‐Modulation‐Encoding (FAME), which codes both amplitude and frequency modulations. Normal hearing listeners were presented with IEEE sentences in the presence of an interfering voice as a function of the number of noise bands (information channels) and signal‐to‐noise level. Sentence recognition with a competing talker was generally improved with the addition of fine structure, and by as much as 60% with 4 fre.
Performance and accuracy test of a WiFi indoor positioning system

Location based-services and personal navigation require the location determination of a user not only in outdoor environments but also indoor. For indoor location already established wireless infrastructure such as WiFi (Wireless Fidelity) or WLAN (Wireless Local Area Networks) can be employed. This approach has the advantage that no costly hardware installations are necessary inside a building if WiFi is already available. The IMST GmbH has developed a software framework called "ipos" for indoor positioning technologies. The principle of the developed platform and the performance of the location determination using WiFi in a localization testbed of IMST GmbH are presented in this paper.
Conceptual Understanding of Causal Reasoning in Physics

College students often experience difficulties in solving physics problems. These difficulties largely result from a lack of conceptual understanding of the topic. The processes of conceptual learning reflect the nature of the causal reasoning process. Two major causal reasoning methods are the covariational and the mechanism‐based approaches. This study was to investigate the effects of different causal reasoning methods on facilitating students’ conceptual understanding of physics. 125 college students from an introduction physics class were assigned into covariational group, mechanism‐based group, and control group. The results show that the mechanism‐based group significantly outperformed the other two groups in solving conceptual problems. However, no significant difference was found in all three groups performance on solving computational problems. Speculation on the inconsistent performance of the mechanism‐based group in conceptual and computational problem solving is given. Detailed analyses of the results, findings, and educational implications are discussed
Far-infrared absorption in liquid nitrogen: a theoretical study

We present a simple theory of the far-infrared collision-induced absorption spectrum of liquid nitrogen. Assuming a quadrupolar induction mechanism, and neglecting the small anisotropy in the N2 intermolecular potential, we represent the spectral profile as the convolution of a single-molecule free-rotation spectrum with an intermolecular translational component. Information theory is used to estimate the least-biased form for the latter, based on our knowledge of its zeroth and second spectral moments (the calculation of M0tr and M2tr is illustrated in the Appendix). In this way we avoid the need to make questionable assumptions about the system dynamics. Our theory contains no adjustable parameters, yet the computed line shapes are in excellent agreement with the available experimental data. Absolute intensities are underestimated by about 40%.
A tunable self-seeded Brillouin/erbium fiber laser utilizing an asymmetrical twin core fiber based Mach–Zehnder interferometer

A tunable self-seeded Brillouin/erbium fiber laser (BEFL) utilizing an asymmetrical twin core fiber based Mach–Zehnder interferometer (ATCF-MZI) is proposed and demonstrated. The proposed self-seeded BEFL has the advantage of being able to generate up to 17 output channels with high optical signal to noise ratio (>10 dB). The Brillouin pump is self-seeded in the laser cavity instead of the extra Brillouin pumping. By bending the ATCF-MZI, an 8 nm wavelength-tunable range is achieved. This self-seeded BEFL shows linear tunability and good stability. Meanwhile, the experimental results indicate that the laser output with operation wavelength away from the free-running cavity mode has better output characteristics.
Functions of vanishing mean oscillation

A function of bounded mean oscillation is said to have vanish- ing mean oscillation if, roughly speaking, its mean oscillation is locally small, in a uniform sense. In the present paper the class of functions of vanishing mean oscil- lation is characterized in several ways. This class is then applied to answer two questions in analysis, one involving stationary stochastic processes satisfying the strong mixing condition, the other involving the algebra H + C.
A High-Resolution VLA and Optical Study of NGC 604

The radio structure of the supergiant H II region NGC 604 in the dwarf spiral galaxy M33 has been observed at 3.6 cm with a resolution of ~2″ (~8 pc) down to an rms noise level of ~15 μJy. At least six radio components can be distinguished embedded in a more extended halo. Each radio component requires ionizing photon fluxes in the range 6-44 times that of Orion A, and the entire nebula requires about 350 times that of Orion A. The rms electron densities are in the range of a few to ~100 cm-3, and the total ionized gas mass is ~3×106 M☉. Even though the photon fluxes required to maintain ionization are large, the radiation density in each radio component is substantially less than that in Orion A due to the much larger size of the radio components in NGC 604. From a comparison of radio and Hα images provided by D. Hunter, we have derived the optical depth at Hα over the face of the nebula. Visual extinctions are greatest toward the bright radio components (2.8 to 1.7 mag) and 0.5 mag over the rest of the nebula. The increased extinction toward the bright radio components implies that the dust is physically associated with these components and requires that the dust is present in the ionized gas. The dust is probably mostly leftover from the natal clouds from which the clusters formed, although some enhancement may have occurred via photoionization of accretion disks associated with the cluster stars and/or molecular cloudlets that have been overrun by the ionization front of the nebula.
Multiview image coding scheme transformations: artifact characteristics and effects on perceived 3D quality

Autostereoscopic multiview 3D displays have been available for number of years, capable of producing a perception of depth in a 3D image without requiring user-worn glasses. Different approaches to compress these 3D images exist. Two compression schemes, and how they affect the 3D image with respect to induced distortion, is investigated in this paper: JPEG 2000 and H.264/AVC. The investigation is conducted in three parts: objective measurement, qualitative subjective evaluation, and a quantitative user test. The objective measurement shows that the Rate-Distortion (RD) characteristic of the two compression schemes differ in character as well as in level of PSNR. The qualitative evaluation is performed at bitrates where the two schemes have the same RD fraction and a number of distortion characteristics are found to be significantly different. However, the quantitative evaluation, performed using 14 non-expert viewers, indicates that the different distortion types do not significantly contribute to the overall perceived 3D quality. The used bitrate, and the content of the original 3D image, is the two factors that most significantly affect the perceived 3D image quality. In addition, the evaluation results suggest that viewers prefer less apparent depth and motion parallax when being exposed to compressed 3D images on an autostereoscopic multiview display.
A new resonant photoacoustic technique for measuring very low optical absorption in crystals and glasses

In this paper, a new photoacoustic technique is described for measuring very low optical absorption in crystals and glasses. The technique differs from the conventional photoacoustic technique in that it does not use a high‐power laser pulse to excite an acoustic signal in the sample, but instead uses a continuous laser with the beam modulated at an acoustic resonance frequency of the sample. By exciting the sample at resonance, the acoustic signal is enhanced by a factor proportional to the quality factor (Q) of the resonance. Because highly transparent crystals and glasses may have a Q on the order of 104 to 106, the technique is orders of magnitude more sensitive than conventional techniques. The Q is enhanced through the use of noncontact acoustic transducers, which also eliminate the problem of background signals due to scattered light. Measurements with various quartz samples have been used to verify the technique. Using a 10‐W continuous laser, the noise level of the resonant photoacoustic techniqu.
Application of permittivity tensor for accurate interpretation of magneto‐optical spectra

The inaccuracies of widely used approximations to the theory of the off‐diagonal elements e1= e’1 + ie‘1 of the permittivity tensor are examined. Errors occurring in the ‘‘diamagnetic’’ case can become important when curve fitting is employed to extract parameter values from Bi‐substituted magnetic garnets. A discrepancy between the exact and approximate forms of the e’1 relation (which is responsible for Faraday rotation and Kerr ellipticity at lower energies) as a function of transition energy is found in the low‐energy (wavelength λ∼1 μm) tails of the lines and originates from the dropping of a nonresonant term from the complete theory. Errors also occur in the line shapes near resonance where the ratio of the excited‐state splitting to the Lorentzian linewidth approaches unity (Δ/Γ→1). A family of curves with Δ/Γ as a parameter is presented, and an exact expression relating Δ/Γ to the resonance value of e’1/e‘0 (where e‘0 is the imaginary part of the diagonal element e0) is derived.
Optical and magnetic properties of porous anodic alumina/Ni nanocomposite films

A simple method to tune the optical properties of porous anodic alumina (PAA) films embedded with Ni is reported. The films display highly saturated colors after being synthesized by an ac electrodeposition method. The optical properties of the samples can be effectively tuned by varying the oxidation time of aluminum. The ultrashort Ni nanowires (100 nm long and 50 nm in diameter) present only fcc phase and show no apparent averaged effective magnetic anisotropy. The coercivity mechanism of the Ni nanowires in our case is consistent with fanning mechanism based on a chain-of-spheres model. PAA/Ni films with structural color and magnetic properties have friability-resistant feature and can be used in many areas, including decoration, display, and multifunctional anti-counterfeiting technology.
The SGS Kinetic Energy And TheViscous Dissipation Equations AsClosure Relations In LES

In this paper the main drawbacks of the large eddy simulation models, present in literature, are analysed and a new LES model is proposed. The closure relation for the generalised SGS turbulent stress tensor: a) complies with the principle of turbulent frame indifference; b) takes into account both the anisotropy of the turbulence velocity scales and turbulence length scales; c) removes any balance assumption between the production and dissipation of SGS turbulent kinetic energy. In the proposed model: a) the closure coefficient which appears in the closure relation for the generalised SGS turbulent stress tensor is theoretically and uniquely determined without adopting Germano’s dynamic procedure; b) the generalised SGS turbulent stress tensor is related exclusively to the generalised SGS turbulent kinetic energy (which is calculated by means of its balance equation) and the modified Leonard tensor. In this paper the main drawbacks associated with the calculation of the viscous dissipation by means of an algebraic model are shown. The calculation of the viscous dissipation is carried out by integrating its exact balance equation. The velocity field obtained from the numerical simulation is analysed by using vortex identification methods D, Q and λ2. The comparative analysis of each identification method is also carried out, highlighting how methods D and Q improperly associate the presence of a vortex to zones of high vorticity while the λ2 method identifies a vortex only when it coincides with a minimum of pressure.
Intense sub-arcsecond structure in the galactic center

The detection of strong radio emission in the direction of the inner 1-pc core of the galactic nucleus is reported. The structure is bright (brightness temperature ^ 10 7 ° K), unresolved (6 ^ O'/l), and distributed within a few seconds of the brightest infrared and radio emission seen previously.
The effect of longitudinal microstriations and their profiles on the drag of flat plates

Abstract The use of surface modifications as a means of reducing viscous drag on a body has potential aerodynamic and hydrodynamic applications. V-grooves of specific dimensions are machined in a longitudinal direction onto the surface of a smooth plate and the resulting effect on the drag force of the plate is observed. Experiments show that V-grooves (riblets) could reduce turbulent skin friction drag by up to 7 per cent, depending on the size of the groove. The drag-reducing performance of riblets with aspect ratios, h/s, of 0.22 and 1 are examined. A boundary layer analysis of the turbulent flow characteristics over the smooth surface and the riblet surfaces indicated an increase in the laminar sublayer thickness and local Reynolds number while reducing the boundary layer thickness for the ribbed surfaces. A maximum drag reduction of 6.83 per cent was recorded for the surface covered with the symmetric riblet, at a Reynolds number of 117 101. It is felt that riblets hamper the momentum and turbulent energy exchange from regions of high velocity to lower-velocity regions. Riblets impede the cross-flow of stream-wise vortices that prevail in the viscous sublayer of a turbulent boundary layer. By suppressing these streamwise vortices, turbulent mixing and hence turbulent shear stress are reduced. Results obtained agree with results suggested from research elsewhere.
Control of coherent structures in reattaching laminar and turbulent shear layers

Etude experimentale du developpement de structures tourbillonnaires a grande echelle dans les couches cisaillees recollees d'un ecoulement sur une marche tournee vers l'aval. Les visualisations de l'ecoulement montrent la formation et l'emergence de structures tourbillonnaires, l'accroissement de l'irregularite de ces structures lorsque la turbulence augmente et la persistence des structures loin en aval du recollement