Miracle-dz/UniFAR-FTUs huggingface dataset:
Enhanced Raman scattering in graphene by plasmonic resonant Stokes emission

Abstract Exploiting surface plasmon polaritons to enhance interactions between graphene and light has recently attracted much interest. In particular, nonlinear optical processes in graphene can be dramatically enhanced and controlled by plasmonic nanostructures. This work demonstrates Raman scattering enhancement in graphene based on plasmonic resonant enhancement of the Stokes emission, and compares this mechanism with the conventional Raman enhancement by resonant pump absorption. Arrays of optical nanoantennas with different resonant frequency are utilized to independently identify the effects of each mechanism on Raman scattering in graphene via the measured enhancement factor and its spectral linewidth. We demonstrate that, while both mechanisms offer large enhancement factors (scattering cross-section gains of 160 and 20 for individual nanoantennas, respectively), they affect the graphene Raman spectrum quite differently. Our results provide a benchmark to assess and quantify the role and merit of each mechanism in surface-plasmon-mediated Raman scattering in graphene, and may be employed for design and realization of a variety of graphene optoelectronic devices involving nonlinear optical processes.
Effects of band nonparabolicity on two‐dimensional electron gas

Energy band nonparabolicity is present in the majority of materials used in heterojunctions, quantum wells, and superlattices. In the present work we derive a simplified dispersion relation for electrons using the k⋅p model. We demonstrate that this dispersion relation can account for nonparabolicity in both narrow and wide gap isotropic semiconductors. We then calculate the carrier effective mass and densities of states for both two‐ and three‐dimensional electron systems. Finally, we derive a simple analytical relation between the carrier concentration and the Fermi energy in a nonparabolic two‐dimensional electron gas. Agreement with a numerical model is demonstrated, while the traditional, parabolic approximation results in a large error. The simplicity of the new approximation allows an intuitive understanding of the nonparabolicity effect in two‐dimensional systems. Therefore, the new approach should be useful for design, characterization, and modeling of quantum semiconductor devices with nonparabo.
General analysis of steady laminar mixed convection heat transfer on vertical slender cylinders

A general analysis has been developed to study fluid flow and heat transfer characteristics for steady laminar mixed convection on vertical slender cylinders covering the entire range from pure forced to pure natural convection. Two uniquely transformed sets of axisymmetric boundary-layer equations for the constant wall heat flux case and the isothermal surface case are solved using a two-point finite difference method with Newton linearization. Of interest are the effects of the new mixed convection parameter, the cylinder heating/cooling mode, the transverse curvature parameter, and the Prandtl number on the velocity/temeprature profiles and on the local skin friction parameter and the heat transfer parameter. The results of the validated computer simulation model are as follows. Depending upon the magnitude and direction of the buoyancy force, i.e., the value of the mixed convection parameter and the heating or cooling mode applied, natural convection can have a significant effect on the thermal flow field around vertical cylinders. Specifically, strong variations of the local skin friction parameter and reversing trends in the heat transfer parameter are produced as the buoyancy force becomes stronger in aiding flow. The skin friction parameter increases with higher curvature parameters and Prandtl numbers. Similarly, the modified Nusselt numbermore » is larger for higher transverse curvature parameters; however, this parameter may reverse the impact of the Prandtl number on the Nusselt number for predominantly forced convection. « less
High speed deformation measurement using digital speckle correlation method

This article discusses an advanced deformation method based on digital speckle correlation method, which is substantially more robust and has greater dynamic range than other full-field imaging technologies such as ESPI and moiré. The system tracks the stochastic pattern applied to the measurement surface with sub-pixel accuracy. The object under test is viewed by a pair of high resolution, digital CCD cameras. Two cameras having been mounted the locations and attitudes were calibrated prior to measurement by combining nonlinear optimization with accurate calibration points. The calibration points were formed by an infrared LED, which moved with 3-D coordinate measurement machine. By using bilinear interpolation square-gray weighted centroid location algorithm, the imaging centers of the calibration points can be accurate. The speckle images of the same measured zone from different directions for the specimen are recorded by two cameras before and after deformation. Then the deformation displacement and strain of the specimen is calculated by these images using digital speckle correlation method and geometrical relation of stereography. The performance was demonstrated with real translation test.
Numerical Methods for Nonlinear Variational Problems

Many mechanics and physics problems have variational formulations making them appropriate for numerical treatment by finite element techniques and efficient iterative methods. This book describes the mathematical background and reviews the techniques for solving problems, including those that require large computations such as transonic flows for compressible fluids and the Navier-Stokes equations for incompressible viscous fluids. Finite element approximations and non-linear relaxation, augmented Lagrangians, and nonlinear least square methods are all covered in detail, as are many applications. "Numerical Methods for Nonlinear Variational Problems," originally published in the Springer Series in Computational Physics, is a classic in applied mathematics and computational physics and engineering. This long-awaited softcover re-edition is still a valuable resource for practitioners in industry and physics and for advanced students.
Lunar Brightness Variations with Phase at 4.3-MM Wave Length

The lunar radio observations and interpretations of Piddington and Minnett (1949) and Gibson (1958) show that the lunar brightness variation with phase at millimeter wave lengths can be used to determine the physical properties of the lunar surface. They found that the millimeter-wave brightness lagged the optical phase, and their interpretation was that the millimeter radiation originates below a surface layer that is a very good thermal insulator. The thickness of this layer could not be determined from observations at one frequency. Observations at different frequencies give different results because of the wave-length dependence of the radio absorption by the surface material. The attenuation in the material increases with decreasing wave length, and therefore it is possible, in principle, to determine surface layer thickness from radio observations at several wave lengths. For this reason, observations of lunar radiation were started at the Naval Research Laboratory at a wave length of 4.3 mm. This is half the wave length used by Gibson (1958) in his earlier studies. The radio telescope used for these observations has been described in detail in a previous publication (Coates 1958). The antenna is a parabolic reflector 10 feet in diameter, and it has a beam width of 6.7 minutes of arc at the wave length of 4.3 mm. This is about one-fifth the diameter of the moon. The receiver was a Dicke-type radiometer.
Influence of eddies on heat transfer in Couette flow

Under creeping flow conditions, we consider the steady Couette flow of a Newtonian fluid between two plates, one of them planar, the other one with a sinusoidal profile. Recent analytical studies on the velocity field revealed the formation of kinematically induced eddies in the valleys of the plate topography and the influence of these eddies on drag force and flow rate. The influence of these eddies on the convective heat transfer is the subject of our paper. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Trapped particles in a distorted dipole field

A dipole magnetic field is analytically compressed and extended to represent a possible effect of the solar wind on the earth's magnetic field on the day and night side of the earth in the earth-sun meridian plane. The first and second adiabatic invariants of particle motion are used to calculate the mirror points of constant energy particles in the compressed and extended fields. The results support and clarify work by previous investigators, showing that shifts in mirror points of particles moving from one field to the other are large at large distances and smaller at lower altitudes. The results are compared to the experimental findings of recent satellites. It is concluded that field distortion may be a major cause of the observed shift in mirror points, but that final resolution of the problem will depend on further determination of the magnetic field on the night side of the earth.
Binary Particle Swarm Optimization (BPSO) Algorithm for Distributed Node Localization

In this paper, we propose a binary particle swarm optimization (BPSO) algorithm for distributed node localization in wireless sensor networks (WSNs). Each unknown node performs localization under the distance measurement from three or more neighboring anchors. The node that gets localized will be used as a reference for remaining nodes. A comparison of the performances of PSO and BPSO in terms of localization error and computation time is presented using simulations in Matlab.
Dual-wavelength fiber mode-locked laser based on graphene saturable absorber

In this paper we present a dual-wavelength fiber mode-locked laser based on CVD-graphene saturable absorber (SA). The laser setup is based on two ring cavities connected by a common branch with a graphene SA. As a gain media erbium (Er) and thulium (Tm) doped active fiber were used. The laser generate optical pulses centered at 1558.5 nm and 1937 nm. The repetition rates and pulse durations were of 23.2 MHz, 16.42 MHz and 0.95 ps, 1.03 ps for the solitons generated in Er- and Tm-doped cavities, respectively.
Gyrokinetic‐magnetohydrodynamic hybrid simulation of the transition from toroidal Alfvén eigenmodes to kinetic ballooning modes in tokamaks

A gyrokinetic‐magnetohydrodynamic (MHD) hybrid simulation code has been developed in order to study high‐n (where n is the toroidal mode number) MHD instabilities driven by energetic particles in finite‐β tokamaks. Here β is the ratio between plasma and magnetic pressures. Specifically, it is observed that as the core plasma β value increases, there is a corresponding transition from the toroidal Alfven eigenmode (TAE) to the kinetic ballooning mode (KBM). The energetic particle mode (EPM) branches of both the toroidal Alfven mode (TAM) and KBM are shown to be important in this transition. KBM are preferentially excited when the energetic particle velocity is small compared to the Alfven velocity.A gyrokinetic‐magnetohydrodynamic (MHD) hybrid simulation code has been developed in order to study high‐n (where n is the toroidal mode number) MHD instabilities driven by energetic particles in finite‐β tokamaks. Here β is the ratio between plasma and magnetic pressures. Specifically, it is observed that as the core plasma β value increases, there is a corresponding transition from the toroidal Alfven eigenmode (TAE) to the kinetic ballooning mode (KBM). The energetic particle mode (EPM) branches of both the toroidal Alfven mode (TAM) and KBM are shown to be important in this transition. KBM are preferentially excited when the energetic particle velocity is small compared to the Alfven velocity.
Evaluation of a Fourth-Order Finite-Volume Compact Scheme for LES with Explicit Filtering

ABSTRACT The accuracy of the large-eddy simulation (LES) of turbulent flows can be increased by using high-order numerical schemes in space and time, due to a decrease in numerical errors. This work investigates a high-order compact finite-volume scheme suitable for LES. The explicit fourth-order Runge-Kutta (RK) scheme for time marching and fourth-order compact schemes for spatial derivatives using a cell-averaged approach are implemented. Different subgrid-scale models and the effect of explicit filtering in a fully turbulent channel flow are studied. In this flow, the fourth-order compact finite-volume method in space, and fourth-order RK in time in conjunction with the dynamic Smagorinsky model with explicit filter-grid size ratio of , show the best agreement with the available reference data.
Detection of colon and rectum cancers by terahertz techniques

Based on experimental analyses of colon and rectal tissues by THz spectroscopy and THz imaging, we show it is possible to distinguish between healthy and cancerous zones. Plots of the absorption coefficient and the index of refraction of the healthy and cancer affected tissues as well as 2-D transmission THz images will be presented. The experimental results will be discussed and the conditions for the tissues discrimination will be established.
Scattering of electromagnetic waves from a half space of densely distributed dielectric scatterers

The scattering of a plane wave obliquely incident on a half space of densely distributed spherical dielectric scatterers is studied. The quasi-crystalline approximation is applied to truncate the hierarchy of multiple scattering equations, and the Percus-Yevick and the Verlet-Weis results are used to represent the pair distribution function. The coherent reflected wave is studied with these approximations. The incoherent scattered wave is calculated with the distorted Born approximation. In the low-frequency limit, closed-form expressions are obtained for the effective propagation constants, the coherent reflected wave, and the bistatic scattering coeficients. Results at higher frequencies are calculated numerically. The advantage of the present approach is that, in the low-frequency limit, it reproduces the effects of specular reflection, Fresnel reflection coefficient, Brewster angle, and Clausius-Mosotti relation. In addition to the classical results, the bistatic scattering coefficients are also calculated. The theory is also applied to match backscattering data from dry snow at microwave frequencies. 25 references.
Magnetic Field Measurements on the Sun and Implications for Stellar Magnetic Field Observations

Results of solar magnetic field measurements in plages, sunspot umbrae, and sunspot penumbrae using high spectral resolution, unpolarized infrared H band spectral data are presented. A Fourier deconvolution analysis scheme similar to that utilized for stellar magnetic field measurements is adopted. As an example, a field strength of 3240 + or - 450 G is determined in a sunspot umbra combined with a value of 2000 + or - 180 G in the associated penumbra. These values are compared with a direct measurement of the spot umbra and penumbra field strengths based on the observed separation of the Zeeman components of the magnetically sensitive lines. Possible origins for the discrepancy between the results inferred by these two different techniques are discussed. The Fourier analysis results confirm the widespread occurrence of kilogauss level fields in the solar photosphere. The implications of the solar results for stellar magnetic field measurements are considered. 45 references.
Fundamental limits on 1/f frequency noise in rare-earth-metal-doped fiber lasers due to spontaneous emission

It is proposed that observed $1/f$ laser frequency noise in rare-earth-metal-doped optical fiber lasers is caused by diffusion of local entropy fluctuations associated with random spontaneous emission events. This heat generation is directly associated with the broad emission spectrum of rare-earth-metal-doped laser glasses. Using data from a well characterized erbium-doped fiber laser, it is shown that the power spectral density of frequency fluctuations resulting from this mechanism is able to achieve excellent agreement with experiment. The proposed theory is expected to be generally applicable to broadly emitting solid-state gain media.
Contrast Research of Two Kinds of Integrated Sorting Algorithms

Boosting and Bagging are two kinds of important voting sorting algorithms. Boosting algorithm can generate multiple classifiers by serialization through adjustment of sample weight; Bagging can generate multiple classifiers by parallelization. Different algorithms are composed of different loss and different integration mode, through integration of Bagging and Boosting algorithm and naïve Bayes algorithm, the Bagging NB and AdaBoost NB algorithms are constructed. Through experiment contrast of UCI data set, the result shows Bagging NB algorithm is relatively stable, it can produce the sorting result superior than that of NB algorithm, AdaBoost NB algorithm is greatly affected by the singular value in data distribution, the result with foundation of NB algorithm is relatively poor on part of data set, and that might have negative influence on the classifier algorithm.
Anomalous Hall effect in spin-polarized two-dimensional electron gases with Rashba spin–orbit interaction

We present details of the analysis of the effect of disorder on the intrinsic anomalous Hall conductivity (AHC) in a spin-polarized two-dimensional electron gas with a Rashba-type spin–orbit interaction. We show that the AHC derived by the Kubo formula vanishes when the Fermi energy is larger than the exchange energy unless the lifetime is spin-dependent. Results obtained by numerical integration of the general expressions of the AHC suggest that the AHC could depend on the lifetime, in contrast to previous results.
Discriminating between Weibull distributions and log-normal distributions emerging in branching processes

We consider the Yule-type multiplicative growth and division process, and describe the ubiquitous emergence of Weibull and log-normal distributions in a single framework. With the help of the integral transform and series expansion, we show that both distributions serve as asymptotic solutions of the time evolution equation for the branching process. In particular, the maximum likelihood method is employed to discriminate between the emergence of the Weibull distribution and that of the log-normal distribution. Further, the detailed conditions for the distinguished emergence of the Weibull distribution are probed. It is observed that the emergence depends on the manner of the division process for the two different types of distribution. Numerical simulations are also carried out, confirming the results obtained analytically.
Crystal Structures of {P(CH3)4}2CuCl4 in Phases I, II and III.

The crystal structures of {P(CH 3 ) 4 } 2 CuCl 4 in phase I, II and III are determined by single crystal X-ray diffractometry. The phase I is isomorphous to the normal phase of {N(CH 3 ) 4 } 2 ZnCl.
Estimating object shape from return flux measurements using a sinusoid beam dither method

Estimating the shape of a target can be an important task in long range surveillance applications. In certain situations obtaining an adequate spatial image of a target can be problematic, especially when the object size and distance requires an exceedingly large receiving aperture, or when significant atmospheric turbulence exists between the target and the receiver. This paper discusses a simple sinusoidal dithering laser illumination scheme that is capable of recovering low spatial frequency information about the object based on the reflected flux. The approach is analyzed in the presence of the corrupting influences of beam jitter. The performance of the method is tested through simulations and laboratory experiments.
A study of transformation groups on manifolds

It might be interesting to ask to what extent the topological and algebraic structures of the group $H(M)$ of the homeomorphisms of a manifold $M$ reflect the topological structure of $M$. In spite of its importance, unfortunately, little has been known about it. Though it seems very difficult to determine the structures of $H(M)$ , many conjectures or problems have been set up by several authors. Among them, our main concern in this paper is a problem raised by A. M. Gleason and R. S. Palais [2], which is given as follows:
Characteristics of oil industry dredge and drilling sounds in the Beaufort Sea

As part of a general study of underwater industrial noises and their effects on bowhead whales, sounds from drilling and dredging operations were measured in the shallow waters (<50 m) of the Canadian Beaufort Sea during August of each year from 1980–1984. The measurements were made from a vertical string of hydrophones at depths of 3, 9, and 18 m suspended from a sparbuoy. Sound sources included drillships logging and drilling, drilling at a caisson‐retained island, transfer dredges, and hopper dredges. Results are presented in spectrum graphs, as sound pressure levels in third‐octave and octave bands, and as overall levels in the 20‐ to 1000‐Hz band. Most energy from these sources was below 1000 Hz. The weakest drilling/dredging sounds measured came from a drillship performing logging operations (122–125 dB re:1 μPa, 20–1000 Hz, range 0.17 km). The strongest sounds came from a hopper dredge underway with a damaged propeller (150 dB, range 0.46 km). Measured data were used to derive regression equations .
Brunner Gland Adenoma with a KRAS G12D Point Mutation

- Brunner gland lesions (BGL) encompass benign proliferations of the homonymous glands and have been designated as hyperplasia, adenoma (BGA), hamartoma or nodule. In general terms, lesions larger than 0.5 cm are considered true neoplasia with an unknown malignant potential and unclear pathogenesis. Genetic alterations have seldom been reported in BGL
What the Design Engineer Needs from the Hydrometeorologist

Abstract The water resources engineer is faced with three major types of problems when designing projects: 1) determination of project yield, 2) determination of project safety, and 3) determination of project scheduling. Hydrometeorology plays an important role in solving each type of problem. The most urgent needs the design engineer has for the expertise of the hydrometeorologist are identified and described. In addition, publications regularly read by design engineers are listed so the hydrometeorologist can effectively communicate his information to the practicing engineer.
THE IMPACT OF BUPIVACAINE DOSE ON POST SPINAL SHIVERING IN CESAREAN SECTION: A RANDOMIZED TRIAL

Objective: The aim of this study was to investigate the relationship between the intrathecal dose of hyperbaric bupivacaine and the incidence and severity of post spinal shivering in parturients undergoing cesarean section Material and methods: A hundred full term pregnant ladies undergoing elective cesarian section were randomized into two equal groups according to bupivacaine dose given for spinal anesthesia. low dose bupivacaine group (LB group) and high dose bupivacaine group (HB group) received 8 mg and 10mg bupivacaine respectively. The incidence and severity of shivering were recorded as primary outcomes. Other measurements were heart rate, mean arterial blood pressure, tympanic membrane temperature, sensory block level.