Miracle-dz/UniFAR-FTUs huggingface dataset:
On the quantization of linearly damped harmonic oscillator

Using the equation of motion for a linearly damped harmonic oscillator as fundamental equation, a condition has been obtained that must be satisfied by its Lagrangian and a number of functional forms has been critically investigated. The Lagrangians that successfully describe a classical damped oscillator have been quantized using Feynman’s elegant path integral method. However, it is found that the expectation value of energy of the damped oscillator in all the cases becomes infinitely large for t→∞, ruling out the possibility of treating the damped quantum system as a one‐body problem.
Particle image velocimetry measurements of a transitional boundary layer under free stream turbulence

Abstract High-speed particle image velocimetry (PIV) measurements of bypass transition reveal the breakdown of the ubiquitous streaks into turbulent spots. Individual streak velocity profiles are examined and contrasted with the root mean square profiles typically reported. An estimation of streak amplitude based on the modulation of the instantaneous boundary layer thickness is proposed. Examination of the PIV velocity fields shows how turbulent spot precursors, identified with concurrent hot-film recordings, consist of streamwise arrangements of positive and negative streaks. As secondary instability progresses, the interface between these streaks is observed to result in turbulent structures. In an attempt to further elucidate the role of the free stream turbulence, correlation maps are generated to determine the extent of the wall-normal fluctuations. Significant damping of the free stream is found within the boundary layer for all Reynolds numbers prior to the onset of spot precursors.
Single flux-quantum memory cells

Detailed investigations have been carried out on two-junction interferometers. These devices have potential as memory elements. Information is stored as single-flux quanta (SFQ cells) in overlapping vortex modes and is destructively read out by switching from a vortex to the voltage state. The devices are fabricated with a lead alloy and the junction oxide is formed by rf oxidation. Most investigations have been done on devices with an area of about 1000 μm2, but storage and reading have also been demonstrated in our smallest interferometers having a size of about 150 μm2. Computer studies of cell properties, especially of the vortex transitions, have given good agreement with experiments. It has also been found that the cell behavior is little affected by loads such as would exist in an array environment.
A Note on the Superoptimal Matrix Algebra Operators

We study the superoptimal Frobenius operators in several matrix vector spaces and in particular in the circulant algebra, by emphasizing both the algebraic and geometric properties. More specifically we prove a series of "negative" results that explain why this approximation procedure is not competitive with the optimal Frobenius approximation, although it could be used for regularization purposes.
Interpretation of polarized Cu K x-ray absorption near-edge-structure spectra of CuO

Polarized Cu K-edge spectra of CuO are calculated by different methods and compared to experiment. Theoretical spectra were obtained via an all-electron full-potential band-structure calculation based on a pseudopotential technique and by a real-space multiple-scattering method involving a self-consistent muffin-tin potential. Self-consistency in the scattering potential is necessary to describe the low-energy part of the ∥z partial spectral component. The low-energy shoulder in the ∥x component observed in the experiment cannot be explained within a one-electron picture and thus apparently has a many-body origin. However, its particular mechanism will be different from the shake-down process suggested for explaining a similar feature in copper-chlorine compounds.
Toward saturation of a discharge-pumped soft x-ray amplifier

Operation of a discharge-pumped 46.9 nm Ne-like Ar amplifier at gain length products up to gl approximately equal to 14 is reported. The laser line intensity is observed to increase exponentially for plasma column lengths up to 15 cm, above which it is observed to saturate. The saturation behavior is discussed. Results of the parameterization of the discharge pumped amplifier and the measurement of the soft x-ray laser pulsewidth also are reported. The use of an axial magnetic field, that limits the maximum plasma compression and decreases the density gradients, is observed to cause a moderate increase of the soft x-ray laser intensity and a beam profile that is more Gaussian.
Stark widths of Xe II lines in a pulsed plasma

In this paper, we present a review of experimental work on Stark broadening of singly ionized xenon lines. Eighty lines, from close UV to the red region of the spectrum, have been studied. Stark halfwidths were compared with experimental data from the literature and modified semi-empirical calculations. A pulsed arc with 95% of helium and 5% xenon was used as a plasma source for this study. Measured electron densities Ne and temperatures T were in the ranges of 0.2–1.6 × 1023 m−3 and 18 300–25 500 K, respectively.
Theoretical modeling of the infrared fluorescence from interstellar polycyclic aromatic hydrocarbons

We have modeled the family of interstellar IR emission bands at 3.3, 6.2, 7.7, 8.6, 11.3, and 12.7 microns by calculating the fluorescence from a size distribution of interstellar polycyclic aromatic hydrocarbons (PAHs) embedded in the radiation field of a hot star. It is found that the various emission bands are dominated by distinctly different PAHs, from molecules with much less than about 80 C atoms for the 3.3 micron feature, to molecules with 10 exp 2-10 exp 5 C atoms for the emission in the IRAS 12 and 25 micron bands. We quantitatively describe the influence on the emergent spectrum of various PAH properties such as the molecular structure, the amount of dehydrogenation, the intrinsic strength of the IR active modes, and the size distribution. Comparing our model results to the emission spectrum from the Orion Bar region, we conclude that interstellar PAHs are likely fully, or almost fully, hydrogenated. Moreover, it is found that the intrinsic strengths of the 6.2 and 7.7 micron C-C stretching modes, and the 8.6 micron C-H in-plane bending mode are 2-6 times larger than measured for neutral PAHs in the laboratory.
Performance degradation assessment of rolling bearing based on bispectrum and support vector data description

In order to realize equipment’s near-zero downtime and maximum productivity a rolling bearing performance degradation assessment is proposed, which is one of the most important techniques. The traditional feature extraction methods based on stationary and Gauss characteristics were unfit to handle non-stationary and non-Gauss signals when the rolling bearing performance begins to degrade. The higher-order statistics (HOS) are fit for handling the non-stationary and non-Gauss signals. Bispectrum not only possesses all the properties of HOS but also has a higher computational efficiency because of a lower order compared with other types of HOS. The support vector data description (SVDD) is a single value classification method which can overcome the problem of a lack of samples in the degradation process of the rolling bearing. A method is proposed in the paper which is based on the bispectrum and SVDD. Firstly, the rolling bearing data of normal state is collected and handled by bispectrum. Based on feature vectors extracted from normal data an SVDD model fitting a tight hypersphere around them is trained. The general distance of test data handled by the bispectrum to this hypersphere is used as the degradation index. In the end, through simulation and a rolling bearing’s accelerated life test, the effectiveness and feasibility of the proposed method is verified.
Ion dynamics in a hybrid simulation of magnetotail reconnection

The 2 1/2-dimensional hybrid simulations are carried out to investigate self-consistent ion dynamics in time-dependent magnetic reconnection. The system dimensions 25 RE × 5 RE are able to accommodate large-scale structures associated with magnetotail reconnection. The simulations are started with two ion populations: hot ions forming the thin current sheet self-consistent with the initial equilibrium two-dimensional tail-like magnetic configuration and cold lobe ions with initially uniform density and temperature. The evolution of the initially stable system is triggered by superposition of a spatially localized resistivity. We find ion acceleration and formation of non-Maxwellian multicomponent ion distributions as predicted by test particle studies. Fine features, such as layers of counterstreaming ions, are found in the distributions of the initially cold lobe ions. The hot current sheet “source,” however, gives rather smeared “output distributions” due to significant spatial overlapping of ion populations with different histories. We find that ions, which are strongly accelerated in the close vicinity of the reconnection site, contribute little to the equilibrium current before reconnection is initiated. Ions, which significantly contribute to the equilibrium current, are either ejected earthward or carried away inside the released plasmoid without significant energy gain during a single “impulsive” interaction with the reconnection fields. Multiple encounters of the acceleration region and quasi-Fermi acceleration of ions trapped between the mirroring earthward boundary and the growing normal magnetic field are found. The simulations also show effective heating of initially cold background ions in the plasma sheet behind the released plasmoid. The tailward speed of energetic ions flowing around the plasmoid along reconnected lobe field lines exceeds the speed of plasmoid. The ions which contribute to these beams are part of the hot population and initially reside in the current sheet. These results match spacecraft observations prior to plasmoid arrival.
3-D tissue typing of prostate tissue based on spectral parameters

Prostate cancer is the highest-incidence and second-leading cancer killer of men in the US. Its diagnosis now relies virtually exclusively on biopsy, but because of the poor specificity and sensitivity of conventional ultrasound many unnecessary biopsies are performed and many justified biopsies fail to sample cancer that is present. Ultrasonic spectrum analysis of radio-frequency (rf) echo signals may offer a means of improving the sensitivity and specificity of ultrasonic means of guiding biopsies. These improvements could reduce unnecessary biopsies, and particularly, false-negative biopsies by improving biopsy guidance. Our results are encouraging for differentiating cancerous from non-cancerous tissue, they typically produce ROC curve areas of approximately 0.9, which represents sensitivity and specificity superior to other imaging means of determining whether biopsy is required.
A Tale of Two Methods

The structural equation modeling approach to testing for mediation is compared to the Baron and Kenny approach. The approaches are essentially the same when the hypothesis being tested predicts partial mediation. The approaches differ, however, in how each tests for complete mediation. Disparities in both theory and statistical estimators are identified and discussed. A strategy for future tests of mediation is recommended.
Electron temperature in magnetohydrodynamic generators

In this note the author has derived expressions for the electron temperature in a linear magnetohydrodynamic generator for three different electrode configurations. In contrast to earlier investigations (which assumed an electron collision frequency independent of electron velocity v), the electron collision frequency is assumed to be proportional to vs. Numerical results have been presented for the cases when S = 1 and 2.
New constructions for perfect hash families and related structures using combinatorial designs and codes

In this paper, we consider explicit constructions of perfect hash families using combinatorial methods. We provide several direct constructions from combinatorial structures related to orthogonal arrays. We also simplify and generalize a recursive construction due to Atici, Magliversas, Stinson and Wei [3]. Using similar methods, we also obtain efficient constructions for separating hash families which result in improved existence results for structures such as separating systems, key distribution patterns, group testing algorithms, cover-free families and secure frameproof codes. © 2000 John Wiley & Sons, Inc. J Combin Designs 8:189–200, 2000
Spatial‐skin effect for eigenvibrations of a thick cascade junction with ‘heavy’ concentrated masses

A spectral problem for the Laplace operator in a thick cascade junction with concentrated masses is considered. This cascade junction consists of the junction's body and a great number 5N=O(ϵ−1) of ϵ‐alternating thin rods belonging to two classes. One class consists of rods of finite length, and the second one consists of rods of small length of order O(ϵ) . The density of the junction is of order O(ϵ−α) on the rods from the second class and O(1) outside of them. The asymptotic behavior of eigenvalues and eigenfunctions of this problem is studied as ϵ → 0. There exist five qualitatively different cases in the asymptotic behavior of eigenmagnitudes as ϵ → 0, namely the case of ‘light’ concentrated (α ∈ (0,1)), ‘middle’ concentrated (α = 1), and ‘heavy’ concentrated masses (α ∈ (1, + ∞ )) that we divide into ‘slightly heavy’ concentrated (α ∈ (1,2)), ‘intermediate heavy’ concentrated (α = 2), and ‘very heavy’ concentrated masses (α > 2). In the paper, we study in detail the influence of the concentrated masses on the asymptotic behavior if α ∈ (1,2). We construct the leading terms of asymptotic expansions both for the eigenvalues and eigenfunctions and prove the corresponding asymptotic estimates. Copyright © 2013 John Wiley & Sons, Ltd.
Topical photodynamic therapy of squamous cell carcinomas in a hairless mouse model

Objectives: To examine therapeutic effects of 5-aminolevulinate (ALA)-mediated photodynamic therapy (PDT) on UVB-induced cutaneous squamous cell carcinomas (SCCs) in a mouse model. Materials and methods: Cutaneous SCCs were established by UVB (280-320 nm) irradiation of hairless mice. In situ fluorescence measurement was used to monitor PpIX formation after the topical application of various concentrations of ALA cream to determine the optimal ALA dose. Therapeutic responses of SCCs to multiple sessions of ALA PDT were examined histologically and quantitatively. TUNEL staining was used to examine apoptosis caused by PDT. Results: After repeated exposure for 18 to 22 weeks (4-5 days/week), multiple nodular and verrucous hyperplasia lesions of various sizes developed at the exposed area. After four sessions of ALA PDT (8% ALA, 3 h incubation, 30 J/cm2 at 20 mW/cm2) a total of 84% of complete response was achieved for small SCCs (1-4 mm, thickness <2.5 mm). TUNEL staining showed that PDT-induced apoptotic cells were distributed evenly from the basal to stratum corneum layers. Conclusions: Topical ALA PDT can trigger apoptosis in SCCs, inhibit SCC growth, and reduce the size and number of tumors in the hairless mouse model. The true clinical value of ALA PDT for the treatment of cutaneous SCC deserves further investigation.
The artificial compression method for computation of shocks and contact discontinuities. I - Single conservation laws

The paper discusses the use of the artificial compression method for the computation of discontinuous solutions of a single conservation law by finite difference methods. The single conservation law has either a shock or a contact discontinuity. Any monotone finite difference scheme applied to the original equation smears the discontinuity, while the same scheme applied to the equation modified by an artificial compression flux produces steady progressing profiles. If L is any finite difference scheme in conservation form and C is an artificial compressor, the split flux artificial compression method CL is a corrective scheme: L smears the discontinuity while propagating it; C compresses the smeared transition toward a sharp discontinuity. Numerical implementation of artificial compression is described.
An Analysis of Frictional Feedback on a Moist Equatorial Kelvin Mode.

Abstract A simple theoretical model of the tropical troposphere is used to study whether boundary layer friction is destabilizing to the Madden–Julian oscillation (MJO) and other convectively coupled moist equatorially trapped Kelvin-like modes. A linear stability analysis is performed on an equatorial beta plane with a continuously stratified atmosphere using a Betts–Miller-like convective parameterization. The troposphere is divided into a frictional boundary layer close to the surface and a frictionless free troposphere. The basic state is horizontally homogeneous and uniformly convecting. The full linear stability problem can be discretized into an eigenvalue problem that is barely computationally tractable. A scaling analysis appropriate for low-frequency, long wavelength modes, such as the MJO, leads to a much simpler eigenvalue problem. Friction is found to be modestly destabilizing for the moist Kelvin mode, increasing its growth rate by 0.03 day−1. It also has a smaller destabilizing effect on th.
Electron bunch shape measurements at the TTF-FEL

The TESLA Test Facility linac has been operated in the first half of 2002 with two bunch compressors to drive the TTF-FEL free electron laser. During this running period, SASE radiation with a wavelength around 100 nm has been routinely delivered to experiments. The longitudinal shape of the electron bunches is a crucial property of the electron beam: a peak current in the order of 1 kA is required to drive the SASE process with the given undulator design, transverse emittance, and energy spread. We report on measurements of the bunch length and shape for different operating conditions of the two bunch compressors.
Computerized Classification Testing with Composite Hypotheses

Reckase (1983) proposed a widely used method of applying the sequential probability ratio test (SPRT; Wald, 1947) to computerized classification testing with item response theory. This method formulates the classification problem as a point hypothesis that an examinee’s ability, θ, is equal to a point, θ1, below the cutscore or a point, θ2, above the cutscore. The current paper argues that the actual goal of classification testing is a composite hypothesis (Weitzman, 1982) that an examinee’s ability θ is in the region of θ either above or below the cutscore, rather than equal to an arbitrarily defined point. A formulation of the SPRT to reflect this testing paradigm is proposed.
Numerical Simulation of the 3D Viscous Flow Around a Vertical Cylinder in Non-Linear Waves Using an Explicit Incident Wave Model

The numerical simulation of 3D wave-body interaction problems in viscous fluid still leads to numerical difficulties, mainly due to large grid and CPU time requirements, especially for wave generation and propagation aspects. The correct treatment of open boundary conditions also remains problematic in direct approaches The method proposed here allows to avoid these problems by solving a modified problem for the diffracted flow only, the incident wave field being explicitly described by potential flow models. A set of results, both on 2D and 3D geometries is presented and commented, showing the capacity of the proposed scheme to solve problems of practical interest in ocean or offshore engineering in an efficient and accurate manner.Copyright © 2004 by ASME
Surface production of H− ions by hyperthermal hydrogen atoms

Hyperthermal atomic hydrogen of energy in the range of 1–10 eV has been produced by electron impact dissociation in a cw 2.45 GHz microwave electron cyclotron resonance (ECR) discharge using a Lisitano‐Coil. The flux and the energy of the hydrogen atoms have been measured by negative surface ionization of the atoms backscattered from pure and cesiated metal surfaces. A hyperthermal atomic hydrogen flux density equivalent to more than 0.5 A/cm2 and a temperature of about 5 eV has been produced for 420 W discharge power under cw condition. These hydrogen atoms can be directed onto an external converter located outside the discharge. This opens up new possibilities for H− ion source design.
Word‐Frequency Effect and Errors in the Perception of Speech

The following interpretation of the word frequency effect—the tendency for common words to be perceived correctly at much lower speech to‐noise ratios than uncommon words—was proposed and verified experimentally. When a stimulus word is only a few decibels below its intelligibility threshold, many of its features—the number of syllables, for example—are still perceived correctly. If enough such features are heard, then only a small number of English words will be consistent with them. Subjects' incorrect responses will be taken from that small set of words, and furthermore they will usually be the relatively common words in the set. If the stimulus is an uncommon word and there are common English words that are phonetically quite similar to it, then these common words will usually be given as (incorrect) responses except at quite high speech‐to noise ratios. This interpretation is confirmed by an analysis of errors in an articulation test. The results show that all subjects tend to give the same incorrect.
On the simulation of a time‐dependent cavity flow of an Oldroyd‐B fluid

In this article we present a finite element method for simulating the time‐dependent flow of an Oldroyd‐B fluid in a lid‐driven cavity, which is a stringent test problem at high Weissenberg number. The key considerations for developing the methodology are the preservation of the positive definiteness of the conformation tensor via the log‐conformation representation and additional diffusion, from second‐order upwind scheme, to smooth the high‐frequency modes. The combination of the log‐conformation representation, finite element method, and an operator‐splitting Lie's scheme, gives us a robust and easy‐to‐implement scheme. We have obtained convergent results when simulating time‐dependent cavity flows. Copyright © 2008 John Wiley & Sons, Ltd.
Energy coupling function and solar wind‐magnetosphere dynamo

The power delivered by the solar wind dynamo to the open magnetosphere is calculated based on the concept of field line reconnection, independent of the MHD steady reconnection theories. By recognizing a previously overlooked geometrical relationship between the reconnection electric field and the magnetic field, the calculated power is shown to be approximately proportional to the Akasofu-Perreault energy coupling function for the magnetospheric substorm. In addition to the polar cap potential, field line reconnection also gives rise to parallel electric fields on open field lines in the high-latitude cusp and the polar cap regions.
Electron-beam probe measurements of electric fields in rf discharges

An electron‐beam probe has been used to make time‐ and space‐resolved measurements of the electric field in a parallel plate rf discharge. Measurements were taken at a time resolution of 5 ns and a field resolution ±1 V/cm at increments of 0.32 cm from the powered electrode. The detection method provides the weighted average of the electric field along the beam trajectory. Measurements of fields less than 20 V/cm were made throughout the entire discharge. Data were obtained for 13.6‐MHz argon discharges at 2.3 and 20 mTorr, and at rf voltage amplitudes of 100 and 600 V at each pressure. The data for the 2.3‐mTorr, 600‐V case show (1) that a propagating double layer forms during the collapse of the sheath, (2) that the field near the electrode points in toward the plasma at the extreme collapse of the sheath, (3) that the collapse and expansion of the sheath proceeds asymmetrically for measurable field values, and (4) that the trajectory averaged electric field in the plasma has an anomalous phase shift an.