Miracle-dz/UniFAR-FTUs huggingface dataset:
Effect of Rain Drops on Corona Discharge in Alternating Current Transmission Lines with a Corona Cage

The dielectric distributed around the surface of electrodes has a significant effect on the corona discharge. Corona discharge in power transmission lines in fine weather is different from that in rainy days as the surface condition is greatly changed. The surface of conductors is filled with the drops of rainwater; hence, the electric field around the conductors will be distorted. The use of a corona cage is an effective and economical means for duplicating corona progress in power transmission lines with lower voltage on the conductor in the cage. The practical conductor was utilized in this experiment under both fine and rainy conditions. The process of corona discharge was recorded and investigated. It was found that the corona discharge turned to be much more intense when rain drops were enlarged and more compressed around the conductor. The corona inception voltage, which is an important parameter of corona discharge, was also gained using an ultraviolet imager (UV imager). The corona inception voltage under the rainy condition was about 25% lower than that under the fine condition. The results of the comparison of audible noise and radio interference were analyzed.
The use of liquid jets to simulate angled drop impact

The liquid jet impact technique has been used extensively for the quantitative study of rain impact. Most of this work has been for normal impact. Although some angled impact studies have been pursued using jets, these have been purely of a qualitative nature. This paper develops the theory of angled drop impact. This allows the establishment of a method of correlating between angled drop and jet impact and obtaining ‘‘equivalent drop’’ curves for jet impact. The correlation is also applied to normal impact. For normal impact it is shown that the previously published equivalent drop curves need to be modified especially at low velocities. The results for both normal and angled impact are discussed with reference to the details of the jet profile, and it is shown that angled jets may be considered as having an average equivalent drop size. The theory of angled impact also explains the shape of damage marks produced by impact and why the amount of damage decreases so rapidly with increasing angle.
Potential exoplanet pseudo-biosignatures

Over 500 exoplanets have been discovered so far, some being rocky, terrestrial planets. Advancing instrumentation permits spectroscopic examination of their atmospheres, and remote detection of potential of biogenic gases. Of particular interest are oxygen and methane, although other gases are considered. Short residence time of these gases implies continued renewal. Abiotic sources are considered at levels that could be misinterpreted as a pseudobiosignature. Photodissociation of water molecules, for example, could produce an oxygen pseudo-biosignature, although generally at low levels. However, large-scale water loss events, as are thought to have occurred on Venus and Mars, could produce a substantial pseudo-biosignature.
Nonlinear response theory on the Keldysh contour

Following the work of Schwinger (1961 J. Math. Phys 2 407), we present a general method for deriving quantum response functions on a closed-loop contour in the complex time plane. We focus on optical response functions of linear to third order and demonstrate by projecting contour time onto the real axis how they connect to Liouville space pathways. This work highlights the close connection between the Keldysh contour and the double-sided Feynman diagrams used in nonlinear optical spectroscopy. In addition, we give a Keldysh contour derivation of the Marcus equation for electron transfer.
Improved Fractal Branch and Bound Method for Stacking-Sequence Optimizations of Laminates

In the present study, a mechanism of fractal pattern of feasible laminates in lamination parameter coordinates is discussed in detail, and a new improved stacking-sequence optimization method is proposed for complicated structures that include both in-plane and out-of-plane lamination parameters. The new method employs a branch-and-bound method for the optimizations of stacking sequences. For the estimation of the fractal branch of stacking sequences, the new method requires approximation of the objective function of the optimizations with a quadratic polynomial using both in-plane and out-of-plane lamination parameters. The new method is applied to a stacking-sequence optimization problem of a maximization of buckling load of a hat-type stiffener structure. The method gives successfully optimal stacking sequences in an excellently short CPU time.
Effective Schottky barrier lowering in silicon-on-insulator Schottky-barrier metal-oxide-semiconductor field-effect transistors using dopant segregation

We present an investigation of the use of dopant segregation in Schottky-barrier metal-oxide-semiconductor field-effect transistors on silicon-on-insulator. Experimental results on devices with fully nickel silicided source and drain contacts show that arsenic segregation during silicidation leads to strongly improved device characteristics due to a strong conduction/valence band bending at the contact interface induced by a very thin, highly doped silicon layer formed during the silicidation. With simulations, we study the effect of varying silicon-on-insulator and gate oxide thicknesses on the performance of Schottky-barrier devices with dopant segregation. It is shown that due to the improved electrostatic gate control, a combination of both ultrathin silicon bodies and gate oxides with dopant segregation yields even further improved device characteristics greatly relaxing the need for low Schottky barrier materials in order to realize high-performance Schottky-barrier transistors.
Termination dependence of surface stacking at 4 H -SiC ( 0001 ) − 1 × 1 : Density functional theory calculations

We study the effect of adsorbates on the relative stability of hexagonal and cubic stacking sequences at the topmost SiC bilayers of $4H\text{-SiC}(0001)\text{\ensuremath{-}}1\ifmmode\times\else\texttimes\fi{}1$ surfaces using first-principles calculations. We investigate F-terminated, OH-terminated, H-terminated, and clean surfaces, and in all cases, the cubic structure is more stable than the hexagonal structure. The energy difference between the two structures, however, significantly depends on adsorbates and is largest on the clean surface while it is smallest on the H-terminated surface. Stabilization of the cubic structure at F-terminated and OH-terminated surfaces is in contradiction to a simple argument based on the electrostatic interaction and we attribute it to orbital hybridization between occupied states of adsorbates and unoccupied states of the substrate surface. The present results suggest a possible means of controlling step bunching and the SiC stacking sequence by surface adsorbates.
Effect of the computational domain on direct simulations of turbulent channels up to Reτ = 4200

The effect of domain size on direct numerical simulations of turbulent channels with periodic boundary conditions is studied. New simulations are presented up to Reτ = 4179 in boxes with streamwise and spanwise sizes of 2πh × πh, where h is the channel half-height. It is found that this domain is large enough to reproduce the one-point statistics of larger boxes. A simulation in a box of size 60πh × 6πh is used to show that a contour of the two-dimensional premultiplied spectrum of the streamwise velocity containing 80% of the kinetic energy closes at λx ≈ 100h.
Measurement of the tt̄ Production Cross Section and Top Quark Mass at DØ

I report on preliminary measurements of the tt production cross section, and a measurement of the top quark mass, performed by the DO Collaboration. The cross section is measured using candidates for dilepton, single‐lepton, and all‐hadronic tt decays collected at DO during RunII of the Tevatron. The results for the various modes are:σtt = 14.3−4.3+5.1 (stat.) −1.9+2.6 (syst.) ± 0.9 (lumi.) pb (dilepton)σtt = 7.2−2.4+2.6 (stat.) −1.7+1.6 (syst.) ± 0.5 (lumi.) pb (lepton+jets)σtt = 7.7−3.3+3.4 (stat.) −3.7+4.7 (syst.) ± 0.5 (lumi.) pb 6(all‐hadronic). The mass measurement uses an improved method to re‐analyze lepton+jets events collected during RunI of the Tevatron, and obtains mt = 180.1 ± 3.6 (stat.) ± 4.0 (syst.) GeV/c2.
Controlling a two-dimensional diffusion process at most until a fixed time

Let be a degenerate controlled two-dimensional diffusion process such that the derivative of is a deterministic function of and . The problem of optimally controlling until time , where is the first passage time of the process to zero and is a fixed constant, is considered. The optimal control is obtained explicitly in an interesting particular case.
The maximum cooling density of a realistic Stirling refrigerator

The maximum cooling density of a Stirling refrigerator operating in a closed regenerative thermodynamic cycle is presented in this paper. The cooling density is the cooling load per unit volume of the refrigerator. Since the size of the refrigerator is involved in the cooling density, the maximization of the cooling density has given a critical compression ratio. The maximum cooling density serves as a better comparison criterion for thermoeconomic considerations.
The impact of system latency on dynamic performance in virtual acoustic environments

Engineering constraints that may be encountered when implementing interactive virtual acoustic displays are examined. In particular, system parameters such as the update rate and total system latency are defined and the impact they may have on perception is discussed. For example, examination of the head motions that listeners used to aid localization in a previous study suggests that some head motions may be as fast as about 175°/s for short time periods. Analysis of latencies in virtual acoustic environments (VAEs) suggests that: (1) commonly specified parameters such as the audio update rate determine only the best‐case latency possible in a VAE, (2) total system latency and individual latencies of system components, including head‐trackers, are frequently not measured by VAE developers, and (3) typical system latencies may result in undersampling of relative listener‐source motion of 175°/s as well as positional instability in the simulated source. To clearly specify the dynamic performance of a parti.
Rational Chebyshev approximations for the error function

This note presents nearly-best rational approximations for the functions erf (x) and erfc (x), with maximal relative errors ranging down to between 6 X 10-19 and 3 X 10-20. for small x because of subtraction error, but they do not provide any alternative. Hastings' (2) approximations for erf (x) are no better, since they explicitly use the constant 1 as an additive term and are chosen to nearly minimize the maximum absolute error rather than the relative error. Clenshaw's (3) Chebyshev series ex- pansions for erf (x)/x come close to minimizing relative error, but his approximations are somewhat inefficient because of his choice of interval and his restriction to polynomials. For a computer subroutine with entries for both erf (x) and erfc (x), cancellation error can be avoided by evaluating erf (x) directly and erfc (x) indirectly (as 1 - erf (x)) when erf (x) is smaller in magnitude than erfc (x), and erf (x) indirectly and erfe (x) directly, otherwise. The changeover point occurs for IxI . 47. In this note we present nearly-best rational approximations for the functions erf (x) and erfc (x) with maximal relative errors ranging down to between 6 X 10-19 and 3 X 10-20. The approximation forms and intervals used are erf (x) x 1.m (X2 ) , lxI 4 where the Rim(z) are rational functions of degree 1 in the numerator and m in the denominator. The relations erf (-x) = -erf (x) and erfc (-x) = 2 - erfc (x) canl be used to evaluate the functions for negative arguments.
Vector features for image matching and image registration

Image matching plays an important role in a variety of applications. For matching images, the features are needed to describe the local content of images. In this paper, we proposed novel features (Vector Features) for image matching and image registration. The vector features are based on the intensity differences of the pixels around the interesting points and characterize the spatial distribution of gray values in an effective and efficient way. In the experiments, the invariance of vector features to image rotation is verified. The vector features perform well on the images of different focal lengths and the multi-view images. The experiment on image registration demonstrates a good result.
Elements of Pattern Theory

Although pattern and image analysis has its conceptual foundations in the mathematical sciences, it is now applied widely in many other areas of science. It embodies the techniques used to evaluate and compare the patterns, shapes, and other images, natural and artificial, that may range from such electronic forms as CAT scans and satellite images to patterns as ancient as the non-random assembly of letters that comprise a language. This book is aimed at both the student of mathematics and the specialist who works with patterns in other fields, such as biology and medicine. It begins by examining the nature of patterns and what distinguishes them from randomness. It then provides the mathematical foundation for the concepts and phenomena introduced. Finally, it provides examples and demonstrations of computer algorithms that permit the reader to recreate and explore some of the patterns discussed in the book.
Assessing Fidelity of Implementation of an Unprescribed, Diagnostic Mathematics Intervention

Abstract This article draws on previously employed methods for conducting fidelity studies and applies them to an evaluation of an unprescribed intervention. We document the process of assessing the fidelity of implementation of the Math Recovery first-grade tutoring program, an unprescribed, diagnostic intervention. We describe how we drew on recent conceptions and standards of fidelity assessment to evaluate the implementation of the program, detailing the process of developing and testing instruments for assessing implementation fidelity, including (a) identifying the intervention's program theory and core components; (b) creating operational definitions of the intervention's core components; (c) developing coding instruments; (d) selecting and training coders; (e) instituting a sampling frame sufficient for generalizing fidelity findings to the study population; and (f) determining the reliability and validity of the data. We also provide a brief overview of the results of the fidelity assessment. We conclude by discussing the aspects of our work that have implications for assessments of fidelity of implementation of unprescribed interventions more generally.
Control of Surface Color of Stainless Steel 304 by KrF Excimer Laser Implant Deposition

Surface coloring of stainless steel 304 by means of photochemical doping and simultaneous deposition using krypton fluoride excimer laser irradiation in ambient silane gas is demonstrated. The surface color is controlled by the deposited film thickness which is a function of the increasing number of laser pulses. The color change is a result of both the surface reflection and the absorption spectra of the films.
Multicolor, visible-light nanolithography

Traditional approaches to improving photolithographic resolution rely on using shorter and shorter wavelengths of electromagnetic radiation. This approach faces ever greater challenges each time the operating wavelength is decreased. Recently, alternative approaches to nanoscale photolithography have been introduced that employ photoresists that are sensitive to multiple colors of visible light. One or more colors of light activate the photoresist, and one or more colors of light can subsequently deactivate it. By controlling the spatial patterns of the colors, it is possible to create features with sizes that are far below the diffraction limit. This approach has been demonstrated for laboratory-based fabrication using multiphoton-absorption-based fabrication, but with improvements in materials it shows great promise for semiconductor lithography as well. A number of approaches to two-color photolithography have been demonstrated. A next generation of schemes that involve a third color of light has the potential to improve the performance of multicolor lithography substantially. The basic premises of both two-color and three-color lithography are discussed, and experimental examples of each type of approach are presented.
Low field electron-nuclear spin coupling in gallium arsenide under optical pumping conditions

In a semiconductor, absorption of circularly polarized light (optical pumping) leads to spin-oriented photoelectrons. In this situation, the nuclei of the crystal are dynamically polarized through their hyperfine interaction with the electronic spins. Consequently the electrons experience a hyperfine magnetic field due to the oriented nuclei which may reach several kilogauss. When this large nuclear field is driven obliquely with respect to the direction of the exciting light, the precession of the electronic spins around the nuclear field leads to a decrease of the electronic polarization along the light excitation: it is a nuclear Hanle effect. This work is an experimental and theoretical study of these effects in weak external magnetic fields, of the order of the local field which characterizes the nuclear spin-spin interactions (a few gauss). Large nuclear fields are obtained at 77\ifmmode^\circ\else\textdegree\fi{}K in strongly doped and compensated $p$-type GaAs samples. We present a model which includes the different effects of the hyperfine coupling when there is a nuclear spin temperature among all the nuclei of the sample: Dynamic polarization, nuclear field, but also, existence of an electronic field acting on the nuclei. We show that a small external field is able to drive the large nuclear field acting on the electrons; consequently the electronic polarization is very sensitive to external fields which are too small to have a direct effect on the electronic spin motion. We study experimentally the variation of the electronic polarization with the direction and magnitude of a small external magnetic field, by measuring the circular polarization of the luminescence light. The experimental results are in quantitative agreement with the theoretical predictions. The usual Hanle Lorentzian depolarization curve is strongly modified in low fields and $W$-like singularities appear around zero field. The experimental values of the average electronic and nuclear fields are in reasonable agreement with theoretical evaluations. These nuclear effects may strongly alter the measurement of the Hanle linewidth in standard optical pumping experiments.
SCORE: A Mid‐Infrared Echelle Format Spectrograph with No Moving Parts

SCORE (SIRTF Cornell Echelle) is a mid‐infrared spectrograph with a resolution of λ/Δλ = 600 covering the entire ground‐based 10 μm atmospheric window in a single exposure. It was built as a proof of concept for one of the SIRTF (Space Infrared Telescope Facility) instruments. It has no moving mechanical parts. SCORE was designed to operate properly upon assembly needing nothing more than a one‐time focus adjustment. The instrument has been adapted for use on the Palomar 200 inch (5 m) Hale telescope and has been used there successfully. The demonstrated starting sensitivity is 105 mJy (1 σ in 100 s at 10 μm). A direct extrapolation to SIRTF conditions predicts a sensitivity between 60 and 90 better than demonstrated on the 200 inch telescope for the same elapsed observing time. Algorithms for reducing the data have been developed in IDL and are discussed. Sample astronomical observations demonstrating SCORE's operation are also presented.
Social media and the classroom

Many years ago, I learned (through eavesdropping on a conversation during lab) that my students had set up their own Facebook group. They told me they were using it to help each other with homework assignments. This year, my daughter took physics at a university. She and her friends were struggling a bit with the online quizzes. I suggested that she set up a Facebook community and add me as a member. I would answer questions and help the group study. My daughter's group used Facebook to get answers to specific questions from the quizzes. They often ended up helping each other because the questions were posed quite late in the evening. Questions ranged from exact copies of the original queries to “Does anyone know what equation to use for this? ” I began to think that, although their grades were improving on the quizzes, they were not gaining any content knowledge. To combat this, I made and posted a few short video clips reteaching the content.
Laser shock‐induced mechanical and microstructural modification of welded maraging steel

The effect of laser‐induced high‐intensity stress waves on the hardness, fatigue resistance, and microstructure in the heat affected zone of welded 18 Ni(250) maraging steel was investigated. Laser‐shock processing increased the hardness and fatigue strength of the weldments. Some melting of the surface was involved during laser‐shock hardening which produced the reverted austenite phase. Microscopic analyses showed an increased dislocation density in the laser‐shocked area.
Spatial and Temporal Variations of Frozen Ground and Snow Cover in the Eastern Part of the Tibetan Plateau

The observations of frost depth and snow water equivalent were carried out at Lhasa, Rikeze and Nagqu in the eastern part of the Tibetan Plateau from July 1993 to March 1999. Also, the routine data at the ten meteorological stations in the same part was analyzed, which covers the observation period. All the stations are located in the seasonally frozen ground region. The main results are as follows: The development of seasonally frozen ground was most remarkable at Nagqu, where the maximum frost depth was 160-200 cm. At Nagqu, the frost penetration began in October and continued until the middle of March. During the frost penetration, except in the midwinter, the soil layer near the surface froze in the night and melted in the daytime. At the thawing stage from April to May, the frozen ground melted from the surface and the frozen soil layer left underground became thin. The efficiency of frost penetration, α, under certain temperature conditions tends to increase with the altitude and the precipitation in the preceding autumn, but α is not influenced by the snow cover. Exceptionally, α is large at Lingzi and Qamdo in spite of their low altitudes. This may be ascribed to the less solar radiation at these stations than other stations, which enhances the frost penetration. The maximum frost depth increases with the altitude except for Lingzi and Qamdo.The days of snow cover increases with the latitude, but long lasting snow cover is not usual. At Nagqu, where the days of snow cover is the second largest among the ten stations, the maximum snow water equivalent was 20 mm, the maximum snow depth was 9 cm and the mean snow density was about 0.2 g cm-3. inter-annual variation of the days of snow cover at Nagqu is almost similar to that at Sogxian. The localized negative correlation between the winter air temperature anomaly and the days of snow cover was found at Nagqu and Sogxian in the winter of 97/98, suggesting the albedo effect of snow cover. The correlation is positive between the precipitation is summer and the days of snow cover at Sogxian in the preceding winter, which apparently corresponds to the snow-hydrological effect. The warm (cold) winter tends to follow the wet (dry) summer with much (little) precipitation respectively. But the relationship between air temperature and precipitation in the summer is not clear.