Miracle-dz/UniFAR-FTUs huggingface dataset:
Simulation and experimental SAR and efficiency study for a dual-band PIFA handset antenna (GSM 900 / DCS 1800) at varied distances from a phantom head

This paper reports a simulation and measurement study on SAR (specific absorption rate) using a dual-band PIFA (planar inverted-F antenna) handset antenna (GSM900/DCS1800). The study investigates the effect of separation distance between the antenna and the user head, in addition to the relationship between the SAR and the antenna efficiency. The SAR was experimentally measured using the DASY4 system and compared to the simulations.
Nonlinear hydrodynamic pressure on dams

The dynamic interaction between nonlinear hydrodynamic pressures and the vibration of a concrete gravity dam is analyzed by coupling Euler's equations with a finite element model of the dam. The earthquake force components in the horizontal and vertical directions are cast as the forcing functions in the finite difference equations for fluid motion. The results are compared with those associated with a rigid dam motion. The pressure distributions are very sensitive to dam vibration and surface wave. For El Centra ground motion recorded on October 15, 1979, the calculated rise of the water surface on Pine Flat Dam was 8 ft (2.7 m), indicating a strong nonlinear effect on hydrodynamic pressures and the potential hazards of surface waves in the reservoir.
Single-Chip Integration of Light-Emitting Diode, Waveguide and Micromirrors

Fundamental technologies for optical interconnection on a Si LSI chip have been developed using conventional silicon process technologies. The optical waveguides with SiOx Ny core and SiO2 cladding layers and Al micromirrors to change the light propagation direction have been fabricated by low-temperature deposition. Moreover, the single test chip integrated with a light-emitting diode (LED), photodiode, waveguides and micromirrors has been fabricated and signal transfer between LED and the photodetector has been achieved.
Monte Carlo simulation of gain compression effects in GRINSCH quantum well laser structures

Gain compression is widely acknowledged to be a serious limitation to the ultimate modulation bandwidth of a semiconductor laser. We have developed a numerical technique to study the gain compression effects in graded-index separate confinement heterostructure (GRINSCH) quantum well laser structures, This technique is based on the combination of the Monte Carlo simulation of the carrier dynamics in the device while under intense stimulated photon emission, and the calculation of the optical gain using a 4/spl times/4 k/spl middot/p Hamiltonian. From the simulated results, we calculated a gain compression coefficient /spl epsiv/=1.1/spl times/10/sup -17/ cm/sup 3/ for a linearly graded quantum well laser structure having a 50 /spl Aring/ In/sub 0.2/Ga/sub 0.8/As well. We find good agreement between our results and published experiments. We have also demonstrated that our calculation method is capable of simulating the gain dynamics in the laser structure, such as those studied with femtosecond pump-probe experimental techniques. >
Pitfalls in the Use of Time as an Explanatory Variable in Regression

Regression of a trendless random walk on time produces R-squared values around . 44 regardless of sample length. The residuals from the regression exhibit only about 14 percent as much variation as the original series even though the underlying process has no functional dependence on time. The autocorrelation structure of these "detrended" random walks is pseudo-cyclical and purely artifactual. Conventional tests for trend are strongly biased towards finding a trend when none is present, and this effect is only partially mitigated by Cochrane-Orcutt correction for autocorrelation. The results are extended to show that pairs of detrended random walks exhibit spurious correlation.
Integration of lead zirconium titanate thin films for high density ferroelectric random access memory

Interests are being focused on types of nonvolatile memories such as ferroelectric random access memory (FRAM), phase change random access memory, or magnetoresistance random access memory due to their distinct memory properties such as excellent write performance which conventional nonvolatile memories do not possess. Among these types of nonvolatile memories, FRAM whose cell structure and operation are almost identical to dynamic random access memory (DRAM) can ideally realize cell size and speed of DRAM. Thus FRAM is the most appropriate candidate for future universal memory where all memory functions are performed with a single chip solution. Due to the poor ferroelectric properties of downscaled ultrathin lead zirconium titanate (PZT) capacitors as well as technical issues such as hydrogen and plasma related degradation arising from embedding ferroelectric metal-insulator-metal capacitors into conventional complementary metal oxide semiconductor processes, current FRAM still falls far below its ideal.
Poole-Frenkel conduction in high alternating electric fields

Measurements are reported for the first time of electronic conduction in silicon monoxide films under alternating fields of high amplitude-sufficiently high to cause a significant lowering of the coulombic barriers at donor-like sites in the material. This ac Poole-Frenkel effect has an entirely different dependence on temperature and frequency from the familiar dc effect and offers insight into the dynamics of relaxation of carrier energy in hopping motion at high electric fields. The interpretation of these results is given in the light of the theoretical model of a modified Poole-Frenkel effect, involving hopping motion of carriers in localized traps between emission and capture at donor sites.
Application of stress smoothing methods to a finite element pile driving analysis

In finite element analysis of pile driving, the nodes of the finite element mesh are the most important locations for output stresses. Especially at the pile‐soil interface, it is essential to obtain accurate nodal stresses. Several global and local stress smoothing methods available in the literature were reviewed and examined. Global methods are found to be computationally expensive, so results obtained from several local stress smoothing methods are compared. It is shown that accurate nodal stresses can be obtained by approximating the stress distribution inside four‐element patches by a polynomial with order equal to the order of the shape functions. Equally good results can be obtained by approximating the stress distribution inside each element by a bilinear surface. When a method taking into account both equilibrium and boundary conditions was applied, a set of ill‐conditioned matrices was produced for the four‐element patches. Such methods are therefore not recommended.
A 2D piezoelectric actuated scanning image acquisition

An image acquisition utilize a 2D piezoelectric actuated optical scanner is presented. The scanner is consisted of a chemically etched tapered single mode optical fiber (SM600) mounted on a X-Y coupled piezoelectric bimorphs operating at the actuators’ resonant frequencies of 2800 Hz and 70 Hz, that generates a40 lines raster scanning light pattern around the area of interest. The image is acquired by a nearby photodetector based on the reflected intensity generated by the scanner. The scanner achieves a 64.5 μm vertical and 7.6 μm horizontal tip displacements with a + 18V input. Initial 1D image acquisition shows the system is capable of resolving a line pattern of 85μm with a gap space of 100μm with a S/N ratio of 10 dB.
Structural coherence and layer perfection in Fe/MgO multilayers

A series of Fe/MgO multilayers was grown on single-crystal MgO(001) substrates at different temperatures using magnetron sputtering. The structural quality of the samples was investigated by x-ray reflectometry, x-ray diffraction and transmission electron microscopy. The results show a strong dependence of the structural quality on the growth temperature. Although good epitaxial layers are obtained at 165 °C, the sample does not exhibit any superlattice diffraction peaks. This effect is shown to be related to a continuous variation of the distance between the Fe layers as well as between the MgO layers.
Second-harmonic generation in the scattering of light by an infinite cylinder

We study the generation of second-harmonic radiation in the interaction of light with an infinite cylinder illuminated perpendicular to its axis by an s- or p-polarized monochromatic electromagnetic wave. With the assumption of a homogeneous and isotropic medium, we derive analytical expressions for the second-harmonic field radiated by the cylinder. The theoretical results are illustrated through calculations of the total scattered power and its angular distribution by employment of a free-electron model for the linear and nonlinear susceptibilities. The scattering cross sections at the harmonic frequency display peaks due to the excitation of resonances.
Dynamic testing of subgrid models in large eddy simulation based on the Germano identity

Normally the Germano identity is used in large eddy simulation (LES) of turbulent flows to evaluate model coefficients so as to minimize the square error associated with replacing a particular model in the identity. However, one can also explicitly evaluate this error and thus establish the accuracy with which a particular model is capable of reproducing the flow features at scales between the grid and test filters. This idea is tested a priori based on tophat filtered experimental data in the far field of a round jet [Liu et al., J. Fluid Mech. 275, 83 (1994)]. Of the models considered, the mixed nonlinear model yields the smallest error. This approach offers the capability to dynamically choose among available parametrizations, based only on the resolved fields during LES.
Optically switchable twist nematic grating based on a dye-doped liquid crystal film

The adsorption rate of methyl red dyes on a polymer surface is studied and determined to be much faster than that on indium-tin-oxide-coated glass. Therefore, an optically switchable twist-nematic grating is fabricated using a dye-doped liquid crystal cell, with a glass substrate coated with a polymer relief grating.
Consistent selection of the number of clusters via crossvalidation

In cluster analysis, one of the major challenges is to estimate the number of clusters. Most existing approaches attempt to minimize some distance-based dissimilarity measure within clusters. This article proposes a novel selection criterion that is applicable to all kinds of clustering algorithms, including distance based or non-distance based algorithms. The key idea is to select the number of clusters that minimizes the algorithm's instability, which measures the robustness of any given clustering algorithm against the randomness in sampling.Anovel estimation scheme for clustering instability is developed based on crossvalidation. The proposed selection criterion's effectiveness is demonstrated on a variety of numerical experiments, and its asymptotic selection consistency is established when the dataset is properly split. Copyright 2010, Oxford University Press.
A comparative study of two-phase flow models relevant to bubble column dynamics

Multiphase flow modelling is still a major challenge in fluid dynamics and, although many different models have been derived, there is no clear evidence of their relevance to certain flow situations. That is particularly valid for bubbly flows, because most of the studies have considered the case of fluidized beds. In the present study we give a general formulation to five existing models and study their relevance to bubbly flows. The results of the linear analysis of those models clearly show that only two of them are applicable to that case. They both show a very similar qualitative linear stability behaviour. In the subsequent asymptotic analysis we derive an equation hierarchy which describes the weakly nonlinear stability of the models. Their qualitative behaviour up to first order with respect to the small parameter is again identical. A permanent-wave solution of the first two equations of the hierarchy is found. It is shown, however, that the permanent-wave (soliton) solution is very unlikely to occur for the most common case of gas bubbles in water. The reason is that the weakly nonlinear equations are unstable due to the low magnitude of the bulk modulus of elasticity. Physically relevant stabilization can eventually be achieved using some available experimental data. Finally, a necessary condition for existence of a fully nonlinear soliton is derived.
The design of an optimized muon beamline

For the Heavy Ion Accelerator Project in South Korea we designed an optimized antimuon beamline by using a simulation with the G4beamline and the TRANSPORT software packages. This research suggests that the optimized muon beamline can transport 2.4×108 antimuons per second to a circle with a radius of 3 cm. In terms of the muon rate, this is competitive with world-leading muon beam facilities.
Gemini Multi-Object Spectrograph Integral Field Unit Spectroscopy of the 167-317 (LV2) Proplyd in Orion

We present high spatial resolution spectroscopic observations of the proplyd 167-317 (LV2) near the Trapezium cluster in the Orion Nebula, obtained during the system verification run of the Gemini Multi-Object Spectrograph (GMOS) Integral Field Unit (IFU) at the Gemini South Observatory. We have detected 38 forbidden and permitted emission lines associated with the proplyd and its redshifted jet. We have been able to detect three velocity components in the profiles of some of these lines: a peak with a 28–33 km s-1 systemic velocity that is associated with the photoevaporated proplyd flow, a highly redshifted component associated with a previously reported jet (which has receding velocities of about 80–120 km s-1 with respect to the systemic velocity and which is spatially distributed to the southeast of the proplyd), and a less obvious, approaching structure that may possibly be associated with a faint counterjet with a systemic velocity of -75 ± 15 km s-1. We find evidence that the redshifted jet has a variable velocity, with slow fluctuations as a function of the distance from the proplyd. We present several background-subtracted, spatially distributed emission-line maps, and we use this information to obtain the dynamical characteristics over the observed field. Using a simple model and extinction-corrected Hα fluxes, we estimate the mass-loss rate for both the proplyd photoevaporated flow and the redshifted microjet, obtaining proplyd = (6.2 ± 0.6) × 10-7 M⊙ yr-1 and jet = (2.0 ± 0.7) × 10-8 M⊙ yr-1, respectively.
The inverse determination of aerodynamic loading from structural response data using neural networks

The prediction and monitoring of aircraft structural fatigue damage is vital for the safe operation of ageing aircraft. The ability to determine aerodynamic loading inversely using structural response data has the potential to significantly improve fatigue monitoring capabilities. This study examines how a Neural Network can be used to estimate and predict aerodynamic loading from structural response data. To simulate aerodynamic loading conditions F/A-18 Empennage fatigue test data which includes the application of both high frequency buffet and low frequency manoeuvre loading will be used. The neural network was trained using response data from several strain gauges as input and known applied loads as output. It was then tested with new data and compared to the known applied loading corresponding to the new data. The network was also tested in its ability to predict the aerodynamic loading across locations different to the locations of the training data.
Sub-Doppler deep-cooled bosonic and fermionic isotopes of potassium in a compact 2D+–3D MOT set-up

We report the sub-Doppler deep-cooled three-dimensional magneto-optical trap (3D MOT) of the fermionic 40K and bosonic 39K isotopes of potassium loaded by a very compact 2D+ MOT with a novel optical design feature. The set-up is meant for studies on the quantum dynamics of a few fermionic and bosonic atoms in an optical dipole trap near and well within quantum degeneracy. The loading rate and atom numbers achieved in the compact simple set-up are comparable to those in the previous set-ups with more elaborate vacuum design. We attained relatively low temperatures of 34 and 30 µK for 39K and 40K after the sub-Doppler cooling process.
A coaxial cavity for measuring the dielectric properties of high permittivity materials

A coaxial cavity has been designed to measure the dielectric constant and loss tangent of high loss, high permittivity materials (i.e. ferroelectrics) at u.h. f. frequencies, with variation of both temperature and dc electric field. Particular attention has been paid to the modification of the simple formulae for a capacitatively loaded cavity when the presence of stray inductance and capacitative effects considerably influence the cavity characteristics. Mention is made of a means by which intermediate frequencies between the cavity harmonics can be obtained by use of an internal tuner.
Dynamics of the formation of polymeric microstructures induced by electrohydrodynamic instability

We perform two-dimensional simulations of an electrohydrodynamic patterning process for a mask-gap-polymer-substrate sandwich. The simulations help us identify the intrinsic pattern resulting from nonlinear interactions to be hexagonal when the mask is unpatterned, consistent with experimental observations. The dynamic evolution of the thin polymer layer under a patterned mask shows that the pillars start to form from corners, propagate along edges, and then grow inwards. This growth sequence, identical to experimental observations, creates a square pattern under a square mask, a hexagonal pattern under a triangular mask, etc. Besides the hexagonal pattern, simulations indicate the conditions under which various different patterns that have been observed in experiments should form.
Investigation of the full spectrum phonon lifetime in thin silicon films from the bulk spectral phonon mean-free-path distribution by using kinetic theory

Phonon dynamics in nanostructures is critically important to thermoelectric and optoelectronic devices because it determines the transport and other crucial properties. However, accurately evaluating the phonon lifetimes is extremely difficult. This study reports on the development of a new semi-empirical method to estimate the full-spectrum phonon lifetimes in thin silicon films at room temperature based on the experimental data on the phonon mean-free-path spectrum in bulk silicon and a phenomenological consideration of phonon transport in thin films. The bulk of this work describes the theory and the validation; then, we discuss the trend of the phonon lifetimes in thin silicon films when their thicknesses decrease.
Control of the seven-degree-of-freedom upper limb exoskeleton for an improved human-robot interface

This study analyzes a practical scheme for controlling an exoskeleton robot with seven degrees of freedom (DOFs) that supports natural movements of the human arm. A redundant upper limb exoskeleton robot with seven DOFs is mechanically coupled to the human body such that it becomes a natural extension of the body. If the exoskeleton robot follows the movement of the human body synchronously, the energy exchange between the human and the robot will be reduced significantly. In order to achieve this, the redundancy of the human arm, which is represented by the swivel angle, should be resolved using appropriate constraints and applied to the robot. In a redundant 7-DOF upper limb exoskeleton, the pseudoinverse of the Jacobian with secondary objective functions is widely used to resolve the redundancy that defines the desired joint angles. A secondary objective function requires the desired joint angles for the movement of the human arm, and the angles are estimated by maximizing the projection of the longest principle axis of the manipulability ellipsoid for the human arm onto the virtual destination toward the head region. Then, they are fed into the muscle model with a relative damping to achieve more realistic robot-arm movements. Various natural arm movements are recorded using a motion capture system, and the actual swivel-angle is compared to that estimated using the proposed swivel angle estimation algorithm. The results indicate that the proposed algorithm provides a precise reference for estimating the desired joint angle with an error less than 5◦.
Determining mass-to-light ratios in elliptical galaxies

If the endstate of cooling hot gas in elliptical galaxies is a population of optically dark, low-mass stars near the galactic cores, the mass-to-light ratio could be expected to vary significantly with projected radius. No strong variation in M/L is observed. To investigate the sensitivity and reliability of observational mass-to-light determinations for a variety of galactic parameters, model galaxies having de Vaucouleurs profiles (but with central cores and outer cutoffs), variable velocity ellipsoid structure, and extended dark halos are constructed. Spurious radial variations in M/L can occur when none are present if the properties of the galactic models are processed similar to observational data. Conversely, when a population of diffuse dark stellar matter is added near the galactic cores, large gradients in M/L can escape detection. However, the magnitude of the central velocity dispersion and its variation with projected radius within the effective radius both suggest that a component of dark stars is unlikely to be more massive than about 30 times the core mass of luminous stars. This restriction is important in establishing the initial mass function of stars in elliptical galaxies and the history of winds and cooling inflows in the interstellar medium. 35 references.
On the use of secondary capture-recapture samples to estimate temporary emigration and breeding proportions

The use of the Cormack-Jolly-Seber model under a standard sampling scheme of one sample per time period, when the Jolly-Seber assumption that all emigration is permanent does not hold, leads to the confounding of temporary emigration probabilities with capture probabilities. This biases the estimates of capture probability when temporary emigration is a completely random process, and both capture and survival probabilities when there is a temporary trap response in temporary emigration, or it is Markovian. The use of secondary capture samples over a shorter interval within each period, during which the population is assumed to be closed (Pollock's robust design), provides a second source of information on capture probabilities. This solves the confounding problem, and thus temporary emigration probabilities can be estimated. This process can be accomplished in an ad hoc fashion for completely random temporary emigration and to some extent in the temporary trap response case, but modelling the complete sam.
Physical Parameters for 12 Planetary Nebulae and Their Central Stars in the Magellanic Clouds

Nebular and central star parameters and elemental abundances of C, N, O, Ne, S, and Ar are presented for the planetary nebulae N2, N5, N43, N54, and N67 in the SMC and P2, P7, P9, P25, P33, and P40 in the LMC. The nebular chemical compositions are affected by nuclear processes in the precursor stars, which may not have been sufficiently massive to synthesize Ne, S, or Ar, which appear to be deficient with respect to their solar abundances by factors of roughly four and five for the LMC and SMC, respectively. Even after excluding nebulae formed by stars in which O apparently was destroyed by nuclear processes, O depletion in the LMC and SMC nebulae is significantly greater than in galactic planetaries. The estimated masses of the 12 remnant central stars range from 0.58 to 0.71 solar mass. 31 references.