Miracle-dz/UniFAR-FTUs huggingface dataset:
Magnetic properties of ultrathin tetragonal Heusler D022-Mn3Ge perpendicular-magnetized films

We investigated the crystal structure and magnetic properties of Manganese-germanium (Mn3Ge) films having the tetragonal D022 structure, with varied thicknesses (5–130 nm) prepared on chromium (Cr)-buffered single crystal MgO(001) substrates. A crystal lattice elongation in the in-plane direction, induced by the lattice mismatch between the D022-Mn3Ge and the Cr buffer layer, increased with decreasing thickness of the D022-Mn3Ge layer. The films exhibited clear magnetic hysteresis loops with a squareness ratio close to unity, and a step-like magnetization reversal even at a 5-nm thickness under an external field perpendicular to the film's plane. The uniaxial magnetic anisotropy constant of the films showed a reduction to less than 10 Merg/cm3 in the small thickness range (≤20 nm), likely due to the crystal lattice elongation in the in-plane direction.
Linear stability analysis of immiscible two-phase flow in porous media with capillary dispersion and density variation

Linear stability analysis of immiscible displacements is carried out for both viscously and gravitationally unstable two-phase flows in porous media with very large adverse viscosity ratios. Capillary dispersion is the proper dissipative mechanism in this case which sets both the preferred length scale and the band width of the spectrum of unstable length scales. The growth rate, the most dangerous and the cutoff wavenumbers, all scale linearly with the capillary number. We show that the instability is governed by fluid properties across the shock rather than those across the full Buckley–Leverett profile. The shock total mobility ratio provides a sufficient condition for the onset of instability; however, it is not an appropriate criterion for predicting the magnitude of the growth rate, particularly for large viscosity ratios. The details of the relative permeability functions are observed to have a significant influence on the stability characteristics. For neutrally buoyant flows the maximum growth rate scales linearly with the viscosity ratio while the most dangerous and the cutoff wavenumbers scale with the square root of the viscosity ratio. In the case of displacements with density contrast, the maximum growth rate scales with the square of the unstable gravity number while the most dangerous and the cutoff wavenumbers scale with an exponent of 1.2, for all viscosity ratios. A marginal stability curve is computed for stable and unstable regions in the parameter space of the viscosity ratio and the gravity number. It is found that flows with unstable viscosity contrasts are more readily stabilized with buoyancy as compared to the viscous stabilization of gravitationally unstable flows.
Explososcan: a parallel processing technique for high speed ultrasound imaging with linear phased arrays.

The data acquisition rate in medical ultrasonic imaging devices is limited by the acoustic propagation velocity in the tissues. Typically in such machines the image lines are produced sequentially one line per transmitted pulse. A parallel processing scheme has been implemented which enables the data acquisition rate to increase by a factor of four through the simultaneous acquisition of four B‐mode image lines from each individual broadened transmit pulse. The higher data rate can be used to increase the image frame rate to produce independent images that can be averaged in the image frame to reduce noise, or to produce a conventional image at standard video frame rates while reducing patient exposure. Alternatively, the field of view can be increased over that of a normal scan without sacrificing frame rate. These advantages are achieved with little reduction in the measured resolution. The design and performance of this device are described. A sample in vivo image is included.
Influence of the illumination source on model-based SRAF placement

Sub-Resolution Assist Features (SRAFs) have been extensively used to improve the process margin for isolated and semi-isolated features. It has been shown that compared to rule-based SRAFs, model-based placement of SRAFs can result in better overall process window. Various model-based approaches have been reported to affect SRAF placements. Even with model-based solutions, the complexity of two-dimensional layouts results in SRAF placement conflicts, producing numerous challenges to optimal SRAF placement for each pattern configuration. Furthermore, tuning of SRAF placement algorithms becomes challenging with varying patterns and sources [1-3]. Recently, pixelated source in optical lithography has become the subject of increased exploration to enable 22/20 nm technology nodes and beyond. Optimization of the illumination shape, including free-form pixelated sources, has shown performance gains, compared to standard source shapes [4-6]. This paper will demonstrate the influence of such different free-form sources as well as conventional sources on model-based SRAF placement. Typically in source optimization, the selection of the optimization patterns is exigent since it drives the source solution. Small differences in the selected patterns produce subtle changes in the optimized source shapes. It has also been previously reported that SRAF placements are significantly dependent on the illumination [1]. In this paper, the impact of changes in the design and/or source optimization patterns on the optimized source and hence on the SRAF placement is reported. Variations in SRAF placements will be quantified as a function of change in the free-form sources. Lithographic performance of the different SRAF placement schema will be verified using simulation.
The generation mechanism of mixed Rossby-gravity waves in the equatorial troposphere

Abstract Numerical experiments are performed to clarify the excitation mechanism of mixed Rossby-gravity waves (Yanai waves) in the tropical troposphere, as well as the selection of zonal wavenumbers 4–5 and of the five-day period. The model used is governed by the primitive equations on an equatorial β-plane. Moisture budgets are calculated explicitly. A nonlinear wave-CISK mechanism produces Yanai waves with the same spectral peaks in wavenumber and frequency as observed. In the absence of antisymmetric lateral forcing, these peaks do not appear distinctly, because the symmetric equatorially trapped modes, i.e., Kelvin-like waves having different spectral peaks, are dominant. It is the lateral antisymmetric forcing which puts the peaks characterizing the antisymmetric Yanai waves in evidence. It appears that Yanai waves of very small wavenumbers (1–3) cannot have large amplitudes because their frequencies are too large for moisture to be effectively supplied for the convection associated with these wave.
On solar emission lines

We draw attention to the large number of unidentified solar emission lines and the various ingenious ideas that have been proposed from time to time to resolve the problem. An attempt is made to tackle the problem on the basis of one fundamental system consisting of an electron and a proton, the Coulomb potential between which is regulated by temperature. Use is made of an equation which has recently been given for the description of such a system
Particle-mesh simulations of clustering in cosmology

Recently developed techniques are used to suggest a prescription for building an optimal particle-mesh or particle-in-cell code. This involves a judicious choice of the Green's function for solving the Poisson equation. Potential difficulties associated with this prescription are considered, and arguments are presented to suggest that these should not be serious. It is also demonstrated that the onset of nonlinearity is not significantly altered by numerical effects. Finally, a quantitative measure is provided for the accuracy with which short scales can be probed. It is applied to various existing codes.
A note on the one-side exact boundary controllabilityfor quasilinear hyperbolic systems

The known theory on the one-side exact boundary observabil- ity for first order quasilinear hyperbolic systems requires that the unknown variables are suitably coupled or satisfy the Group Property in boundary conditions on the non-observation side (see (1)-(2), (11)). In this paper we illustrate, with an inspiring example, that the one-side exact boundary ob- servability can be realized by means of a suitable coupling of the unknown variables in quasilinear hyperbolic system itself instead of in boundary con- ditions. Moreover, an implicit duality between the one-side exact boundary controllability and one-side exact boundary observability is also revealed in this situation.
A Study of Computer Control of Motion of a Mechanical Arm : 1st Report, Calculation of Coordinative Motion Considering Singuler Points

This study deals with the manipulator control problem from the dynamical standpoint where the time factor plays an important role. It includes a coordinate transformation of the position and posture and the force and moment, a control of the coordinative motion, and a visual feedback control. In the first report, the coordinate transformation necessary to control the coordinative motion of the hand of a manipulator has been analyzed. As the result, it is shown that there are several singular points determined by the arm mechanism. At these singular points, the kind of the configuration of the arm for the same position and posture of the hand changes and the number of degrees of freedom of the hand decreases. Utilizing these results, a method of calculation of the global coordinative motion is proposed. This method eliminates the difficulties which may arise at the singular points and enables a change of the kind of the configuration.
Conductivity of a Medium Containing a Dense Array of Perfectly Conducting Spheres or Cylinders or Nonconducting Cylinders

The effective electrical conductivity σ is computed for a composite medium consisting of a dense cubic array of identical, perfectly conducting spheres imbedded in a medium of conductivity σ0. When f, the fractional volume occupied by the spheres, is near its maximum value π/6, the result is σ/σ0=−(π/2)log [(π/6)−f]+…,(π/6)−f≪1. This result exhibits the singularity of σ at f=π/6, when the spheres touch each other. The previous results of Maxwell, of Rayleigh and of Meredith and Tobias are not valid near the singularity and they fail to reveal it. For f=0.5161 our result yields σ/σ0=7.65, while the measurement of Meredith and Tobias yielded σ/σ0=7.6. For a medium containing a square array of perfectly conducting circular cylinders we obtain σ/σ0=π32/2[(π/4−f)]12+…,(π/4)−f≪1. This result agrees well with the numerical results of H. B. Keller and D. Sachs. We also prove that for any value of f, σ/σ0 for a medium containing a square array of nonconducting cylinders is the reciprocal of σ/σ0 for the same array .
Astigmatic Beam Tracing for Gtd/Utd Methods in 3-d cOmplex Environments

Asymptotic techniques are usually employed for electromagnetic analysis of large and complex scenarios. Determination of ray paths from source to observation region is the first stage of a computation. Beam tracing methods, formerly developed for computer graphics, ensure continuous scenario coverage overcoming drawbacks of usual ray tracing. In this paper these are extended for application to electromagnetic analysis and improved to solve for multiple order interactions with scatterers by resorting to the astigmatic beam scheme. Wedge diffraction is solved recursively by minimising an aberration error. A numerical analysis has been performed for comparisons with a backward ray tracer showing a good agreement of results.
A robust adaptive generalized sidelobe canceller with decision feedback

Conventional generalized sidelobe canceller (GSC) is sensitive to a mismatch between the estimated and actual direction of arrival (DOA) of the desired signal. Such a mismatch induces signal cancellation in the GSC, and it severely degrades the beamforming performance. In this paper, we propose a new decision feedback (DF) technique to increase the robustness against the DOA mismatch. Our new scheme introduces a blind equalizer and a feedback filter in the GSC structure. We first derive Wiener solutions for the DF-GSC with perfectly matched and mismatched DOA and show that the problem of signal cancellation can be avoided. Then, we consider the adaptive GSC implementation in which the least-mean-square (LMS) algorithm is used for weight adaptation. In addition to the improved robustness, the proposed scheme also remedies the slow convergence problem inherent in the conventional adaptive GSC structure. The convergence behavior of the LMS-based DF-GSC is fully analyzed and the analytic signal-to-interference-plus-noise ratio (SINR) is also derived. Finally, simulation results demonstrate that while the proposed structure can considerably enhance the overall performance, it has greatly improved robustness as compared to other existing robust adaptive beamformers.
Interparticle interactions and polarization effects in colloids

The physics of simple colloidal systems is usually dominated by three independent length scales: the particle size, the average interparticle distance, and the range of the interparticle potential. The dispersed particles typically have characteristic dimensions in the range 5 to 100 nm, often with spherical or cylindrical symmetry. Dispersion densities vary over volume fractions ranging from 0.5 to 10/sup -4/, with the corresponding mean interparticle distances ranging from about 1 to 10 diameters (in spherical systems). The interaction potential may be very short ranged (hard sphere), very long ranged (Coulomb or dipolar), or anywhere in between (screened Coulomb), and the correlations exhibited in the dispersion may be gas-like, liquid-like or crystalline, depending on the range of the potential relative to the interparticle distance. This rich phase behavior is responsible for the remarkable importance of colloidal studies in many areas of condensed matter physics and biophysics, but it poses often intractable problems in developing the statistical mechanical descriptions necessary for an understanding of scattering data from colloids. This paper will review the considerable recent progress in this field, in the context of SANS experiments on colloids in which the potentials are dominated by either screened Coulomb or magnetic dipolar interactions; inmore » the case of magnetic colloids (ferrofluids), the use of polarization analysis will also be discussed. 32 refs., 4 figs.« less
Improved problem formulation for signal extrapolation

The extrapolation of a discrete-time signal is considered. Iterative algorithms for this problem require numerous iterations for accurate results. An analysis shows the very large condition number of the linear equations, and thus the slow convergence. One way to circumvent the slow convergence is to use better algorithms, such as truncated singular value decomposition (TSVD) or special conjugate gradient algorithms. An improved problem formulation is proposed. It is shown how to reduce the condition number by some orders of magnitude with a more realistic low-pass filter matrix. The modified system is solved by TSVD with uncritical dependence of the solution error on the number of singular values involved. <<ETX>>
Nonorthogonal wavelet packets

The notion of orthonormal wavelet packets introduced by Coifman and Meyer is generalized to the nonorthogonal setting in order to include compactly supported and symmetric basis functions. In particular, dual (or biorthogonal) wavelet packets are investigated and a stability result is established. Algorithms for implementations are also developed.
ON UNDAMPED HEAT WAVES IN AN ELASTIC SOLID

This paper is concerned with thermoelastic material behavior whose constitutive response functions possess thermal features that are more general than in the usual classical thermoelasticity. After a general development of the constitutive equations in the context of both nonlinear and linear theories, attention is focused on the latter. In particular, the one-dimensional version of the equation for the determination of temperature in the linearized theory provides an easy comparative basis of its predictive capability: In one special case where the Fourier conductivity is dominant, the temperature equation reduces to the classical Fourier law of heat conduction, which does not permit the possibility of undamped thermal waves; however,'in another special case in which the effect of conductivity is negligible, the equation has undamped thermal wave solutions without energy dissipation.
Enhanced broadband photoresponse of Ge/CdS nanowire radial heterostructures

CdS/Ge nanowire heterojunction has been grown by chemical deposition of CdS on Ge nanowire templates. Transmission electron micrographs show the growth of core-shell Ge/CdS nanowire radial heterostructures. Raman spectra reveal the confinement of phonons in nanocrystalline CdS shell grown on Ge nanowires. A diodelike behavior in I-V characteristics of Ge/CdS heterojunction is observed due to the formation of rectifying junction between CdS shells and Ge nanowire cores. An improved photocurrent spectrum of Ge/CdS heterojunction nanowires with broadband response from visible to near-IR region is demonstrated.
Imaging of pipeline defects based on extraction of mode-converted guided waves

Guided waves are becoming popular for pipeline monitoring because of its sensitivity to small defects and long sensing range. Several research groups have explored ultrasonic imaging techniques for pipeline monitoring by fully utilizing the advantageous characteristics of guided waves. They have generated torsional mode and measured torsional reflections from pipe defects using expensive shear-mode piezoelectric transducers or electromagnetic acoustic transducers (EMAT), and then extracted crack-induced flexural modes as a post processing step. In this study, these existing techniques are further advanced to perform ultrasonic imaging by measuring the crack-induced flexural modes only, eliminating the necessity of the torsional mode information. This enables us to replace the expensive shear-mode transducers used to measure the torsional reflections with inexpensive compression-mode macro fiber composite (MFC) transducers. First, a magnetostrictive transducer attached at one end of the pipe is used for the excitation of a pure torsional mode in the pipe specimen. Then, the torsional mode propagates through the pipe, and the reflections are created by the interaction of the incident torsional mode with the crack. Due to the sensing characteristics of MFC transducers, only the crack-induced flexural modes can be measured by multiple MFC transducers placed along the circumference near the excitation magnetostrictive transducer. Using the normal mode expansion technique, each individual flexural mode among all reflected signals is extracted. By propagating this crack-induced flexural mode back in the space considering its dispersion characteristics, the location of the crack is visualized.
Photoluminescence imaging of silicon wafers

Photoluminescence imaging is demonstrated to be an extremely fast spatially resolved characterization technique for large silicon wafers. The spatial variation of the effective minority carrier lifetime is measured without being affected by minority carrier trapping or by excess carriers in space charge regions, effects that lead to experimental artifacts in other techniques. Photoluminescence imaging is contactless and can therefore be used for process monitoring before and after individual processing stages, for example, in photovoltaics research. Photoluminescence imaging is also demonstrated to be fast enough to be used as an in-line tool for spatially resolved characterization in an industrial environment.
Bifurcation structure of a laser with pump modulation

The nonlinear phenomena that occur in the laser rate equations with periodic pump modulation are studied numerically. The gross bifurcation structure of the system covering a large range of the parameters can be classified through the concept of nonlinear resonances and torsion numbers, which have already been used to great advantage in other nonlinear oscillatory systems. The pump-modulated laser rate equations are closely related to the Toda oscillator.
Investigations into the Neural Basis of Structured Representations

Title of Dissertation: INVESTIGATIONS INTO THE NEURAL BASIS OF STRUCTURED REPRESENTATIONS Carol Susan Whitney, Doctor of Philosophy, 2004 Dissertation directed by: Professor Amy Weinberg Departments of Computer Science and Linguistics The problem of how the brain encodes structural representations is investigated via the formulation of computational theories constrained from the bottomup by neurobiological factors, and from the top-down by behavioral data. This approach is used to construct models of letter-position encoding in visual word recognition, and of hierarchical representations in sentence parsing. The problem of letter-position encoding entails the specification of how the retinotopic representation of a stimulus (a printed word) is progressively converted into an abstract representation of letter order. Consideration of the architecture of the visual system, letter perceptibility studies, and form-priming experiments led to the SERIOL model, which is comprised of five layers: (1) a (retinotopic) edge layer, in which letter activations are determined by the acuity gradient; (2) a (retinotopic) feature layer, in which letter activations conform to a monotonically decreasing activation gradient, dubbed the locational gradient; (3) an abstract letter layer, in which letter order is encoded sequentially. (4) a bigram layer, in which contextual units encode letter pairs that fire in a particular order; (5) a word layer. Because the acuity and locational gradients are congruent to each other in one hemisphere but not the other, formation of the locational gradient requires hemisphere-specific processing. It is proposed that this processing underlies visual-field asymmetries associated with word length and orthographic-neighborhood size. Hemifield lexical-decision experiments in which contrast manipulations were used to modify activation patterns confirmed this account. In contrast to the linear relationships between letters, a parse of a sentence requires hierarchical representations. Consideration of a fixed-connectivity constraint, brain imaging studies, sentence-complexity phenomena, and insights from the SERIOL model led to the TPARRSE model, in which hierarchical relationships are represented by a predefined distributed encoding. This encoding is constructed with the support of working memory, which encodes relationships between phrases via two synchronized sequential representations. The model explains complexity phenomena based on specific proposals as to how information is represented and manipulated in syntactic working memory. In contrast to capacity-based metrics, the TPARRSE model provides a more comprehensive account of these phenomena. INVESTIGATIONS INTO THE NEURAL BASIS OF STRUCTURED REPRESENTATIONS