Miracle-dz/UniFAR-FTUs huggingface dataset:
Underwater solar light field: analytical model from a WKB evaluation

An analytical expression for the underwater radiance distribution due to a purely 'delta function' sun is discussed. The expression derives from a WKB evaluation of the path integral solution for time-dependent radiative transfer, integrated over long times, and does not involve a small-angle approximation. However, a diffusion-limiting length scale previously found in the small-angle approximation also arises in this evaluation, suggesting that is plays a physically important role (independent of approximation schemes) in governing the structure and evolution of the radiance distribution. In its present form, the analytical expression reproduces the shape of the downwelling radiance distribution for angles as large as 90 degree(s), but is inadequate for the upwelling component. However, the poor modeling of the upwelling component is not a limitation of the WKB approximation, but is most likely due to the simplistic treatment of the phase function. An effort is underway to more carefully handle the phase function within this WKB framework.
Parametric oscillation at 3.2 mu m in KTP pumped at 1.064 mu m

The author reports the stable generation of 0.2-W average power IR pulses around 3.2 mu m from the KTP parametric oscillator pumped by the Nd:YAG laser at 1.064 mu m. In addition, improved Sellmeier's equations, which correctly predict almost all of the nonlinear experiments thus far reported, are presented, together with the absolute values of d/sub 31/ and d/sub 32/. >
Shock-induced PDR in the Herbig-Haro object HH 2

We report mid-infrared ($5-17\mu m$) and SO, CO, $^{13}$CO millimeter line observations of the protostellar jet HH~2 and the parental molecular cloud. We have detected for the first time mid-infrared emission along a protostellar jet. We find that the outflowing gas extends much further away than the Herbig-Haro object HH~2, showing direct evidence that downstream gas has been accelerated by previous outflow events. These gas layers appear to have been detached from the parental cloud, as they are distributed around a cavity, probably dug by protostellar outflow(s). SO emission is detected in shocked gas regions associated with outflows. The UV field produced in the strong shock region HH~2H-A has produced a low-excitation Photon-Dominated Region at the walls of the cavity, which is detected in the PAH emission bands and in the continuum between 5 and $17\mu m$. This continuum arises from very small grains transiently heated by a FUV field G $\simeq 20G_0$, which probably formed from evaporation of dust grain mantles in shocks.
Micromachined 300 GHz high Q resonant slot frequency selective surface filter

The design of a low loss quasi-optical beam splitter which is required to provide efficient diplexing of the bands 316.5–325.5 GHz and 349.5–358.5 GHz is presented. To minimise the filter insertion loss, the chosen architecture is a three-layer freestanding array of dipole slot elements. Floquet modal analysis and finite element method computer models are used to establish the geometry of the periodic structure and to predict its spectral response. Two different micromachining approaches have been employed to fabricate close packed arrays of 460 μm long elements in the screens that form the basic building block of the 30 mm diameter multilayer frequency selective surface. Comparisons between simulated and measured transmission coefficients for the individual dichroic surfaces are used to determine the accuracy of the computer models and to confirm the suitability of the fabrication methods.
Defense and illustration of time-resolved pulsed thermography for NDE

After defining a good usage of pulse thermograms, in particular their ‘rectification’ thanks to log-log plot, and fitting by the TSR (thermographic signal reconstruction) technique, it is demonstrated that a simple and efficient normalisation is possible. The optimisation of pulse thermography is proposed based on two complementary approaches: the early detection of contrasts and the use of the TSR technique with logarithmic derivation. It is shown that in these conditions the quality of thermal images is greatly enhanced (reduction of blurring) and the accuracy of the identified defect parameters (depth and thermal resistance) is better. Based on experimental and simulated results it is shown that to optimise pulse stimulated thermography it is necessary to consider two parameters: the signal-to-noise ratio of the defect contrast and the precociousness of its exploitation. It is shown that this second parameter, which has been neglected by most of the users of pulse thermography who identified the defects parameters from the maximum contrast, can be improved by the logarithmic derivation.
Multi‐variate stochastic volatility modelling using Wishart autoregressive processes

A new multi‐variate stochastic volatility estimation procedure for financial time series is proposed. A Wishart autoregressive process is considered for the volatility precision covariance matrix, for the estimation of which a two step procedure is adopted. The first step is the conditional inference on the autoregressive parameters and the second step is the unconditional inference, based on a Newton‐Raphson iterative algorithm. The proposed methodology, which is mostly Bayesian, is suitable for medium dimensional data and it bridges the gap between closed‐form estimation and simulation‐based estimation algorithms. An example, consisting of foreign exchange rates data, illustrates the proposed methodology.
Automatic alignment of a high-performance interferometric medical imaging device

For optimal performance of a high-precision optical system, careful and stable alignment is necessary. To achieve robust alignment in a commercial system, performance tradeoffs or significant redesigns are often made. We have developed subsystems that allow us to automatically monitor and control the optical system alignment, allowing us to minimize the changes necessary between high-performance research systems and practical commercial designs. In addition, this can allow ruggedization of systems that would be too unstable otherwise. We have implemented such an alignment system in a high-performance medical interferometric imaging device with a focus on maintaining high throughput and allowing for significant system customization. The system is able to maintain near-optimal alignment without any user interaction over a large thermal range and can compensate for misalignments during initial system construction or resulting from shock events. With careful planning, the cost of such a system can be kept reasonably low and it requires minimal interruption to a normal user's workflow. We will discuss the basic principles and necessary considerations for the implementation of such a system, using the developed system as a case study. Similar technology can be used in many optical devices and is especially relevant if access by a trained technician is difficult or costly.
Fiber Bragg grating sensor and waveguide grating sensor

Several new designes of different type fiber Bragg grating(FBG) sensors, including long range strain sensor, pressure sensor, and displacement sensor, have been introduced. A new concept of sliced fiber Bragg grating as free space optical element has been presented. Some new waveguide Bragg grating writing technologies have been introduced.
Three Problems In Nonlinear Dynamics: Time Delay, Fractionality And Synchronization

Three problems in nonlinear dynamics are studied with concern to the effects of time history dependent functions on steady state behavior. In each problem we consider either a single oscillator or a system of oscillators. The appearance of the time history dependence varies over the problems, and is be introduced either as a delayed term or a fractional derivative. In our first problem, a van der Pol type system with delayed feedback is explored by employing a two variable expansion perturbation method. The resulting amplitude-delay relation predicts two Hopf bifurcation curves, such that in the region between these two curves oscillations will be quenched. The perturbation results are verified by comparison with numerical integration. The second and third problems are on the subject of fractional derivatives. In analyzing these problems we look to extend classic perturbation methods to the treatment of fractional derivatives. In the second problem we also consider a single oscillator. The oscillator may be described as a damped Mathieu type where the damping term has been replaced by a fractional derivative. The order of the fractional derivative considered ranges from 0 to 1. Both lowest order and higher order approximations for the n = 1 transition curves, which separate regions of stability from instability, are found using the method of harmonic balance. An approximation for the n = 0 transition curve is also obtained. In the limiting cases of the fractional derivative's order, α, being 0 or 1, the fractional Mathieu equation being considered respectively reduces to the familiar undamped and damped Mathieu equations. The undamped and damped Mathieu equations are well studied and our results may be compared with the known results in these cases. Through these comparisons conclusions are drawn as to the validity of assumptions made in applying the method of harmonic balance as well as the effect of the fractional derivative. In the third problem, the stability of the in-phase and out-of-phase modes of a pair of fractionally-coupled van der Pol oscillators is studied. A two variable perturbation method is applied to the system's corresponding variational equations to obtain expressions for the transition curves separating regions of stability from instability. The perturbation results are validated with numerics and, as in the second problem, through direct comparison with known results in the limiting cases of fractional derivative order taking on the values of α = 0 and α = 1. iii ACKNOWLEDGEMENTS I would …
MID-INFRARED SPECTRA OF TRANSITIONAL DISKS IN THE CHAMAELEON I CLOUD

We present 5–40 μm Spitzer Infrared Spectrograph spectra of a collection of transitional disks, objects for which the spectral energy distribution (SED) indicates central clearings (holes) or gaps in the dust distribution, in the Chamaeleon I star-forming region. Like their counterparts in the Taurus-Auriga star-forming region that we have previously observed, the spectra of these young objects (1–3 Myr old) reveal that the central clearings or gaps are very sharp-edged, and are surrounded by optically thick dusty disks similar to those around other classical T Tauri stars in the Chamaeleon I association. Also like the Taurus transitional disks, the Chamaeleon I transitional disks have extremely large depletion factors for small dust grains in their gaps, compared to the full accretion disks whose SEDs are represented by the median SED of Class II objects in the region. We find that the fraction of transitional disks in the Chamaeleon I cloud is somewhat higher than that in the Taurus-Auriga cloud, possibly indicating that the frequency of transitional disks, on average, increases with cluster age. We also find a significant correlation between the stellar mass and the radius of the outer edge of the gap. We discuss the disk structures implied by the spectra and the constraints they place on gap-formation mechanisms in protoplanetary disks.
A Texture Synthesis Algorithm Based on SFLA-PSO and Block Increasing

A texture synthesis algorithm based on SFLA-PSO and block increasing is presented for example-based synthesis. It can be used to speed up texture synthesizing through using the texture block of which size is increased by times of two during the process of texture synthesis; As the searching tactics of texture block matching, SFLA and PSO are combined to accelerate and improve the global searching performance. The experimental results prove that the algorithm can evidently accelerate texture synthesis on the premise of fine synthesis quality, and overcome the defect of easily falling into local optimal solution of PSO algorithm.
Layout optimization of large‐scale pin‐jointed frames

Computerized layout (or “topology”) optimization was pioneered almost four decades back. However, despite dramatic increases in available computer power and the application of increasingly efficient optimization algorithms, even now only relatively modest sized problems can be tackled using the traditional “ground structure” approach. This is because of the need, in general, for the latter to contain every conceivable member connecting together the nodes in a problem. A simple, but effective solution method capable of tackling problems with large numbers of potential members (e.g. >100,000,000) is presented. Though the method draws on the linear programming technique of “column generation”, since layout optimization specific heuristics are employed it is presented as an iterative “member adding” method. The method requires a ground structure with minimal connectivity to be used in the first iteration; members are then added as required in subsequent iterations until the (provably) optimal solution is found.
Geodesics: a tool for solving material properties inverse problems

Inverse problems in mechanics of solids and structures are gaining more importance. One of the reason behind that is the advances in digital image processing and computer vision technologies. Traditionally, the user would locate features on the object or attach grids to it. The deformation of those features (or grids) would give an indication of the displacements undergone by some points on the surface of the object due to the deforming forces. Knowledge of the deforming forces and the displacements is usually enough to approximate the material properties of the object. In this paper we suggest a method by which a featureless object can be interrogated for its material properties. No invasive procedures are necessary. The method uses geodesics of the deformed and undeformed surfaces to obtain the displacements due to known deforming forces. Finite element method is then used to deduce the material properties distribution of the object. The method is proven to work only for elastic deformations that would leave a deformed surface developable with respect to the undeformed one. <<ETX>>
Piezoelectric oxide semiconductor field effect transistor touch sensing devices

This work presents piezoelectric oxide semiconductor field effect transistor (POSFET) based touch sensing devices. These devices are fabricated by spin coating thin (∼2.5 μm) piezoelectric polymer film directly on to the gate area of metal oxide semiconductor (MOS) transistor. The polymer film is processed in situ and challenging issues such as in situ poling of piezoelectric polymer film, without damaging or altering the characteristics of underlying MOS devices, are successfully dealt with. The POSFET device represents an integral “sensotronic” unit comprising of transducer and the transistor—thereby sensing as well as conditioning (and processing) the touch signal at “same site. ”
The corrected VIF (CVIF)

In this paper, we propose a new corrected variance inflation factor (VIF) measure to evaluate the impact of the correlation among the explanatory variables in the variance of the ordinary least squares estimators. We show that the real impact on variance can be overestimated by the traditional VIF when the explanatory variables contain no redundant information about the dependent variable and a corrected version of this multicollinearity indicator becomes necessary.
Sampling Correlation Matrices in Bayesian Models With Correlated Latent Variables

Hierarchical model specifications using latent variables are frequently used to reflect correlation structure in data. Motivated by the structure of a Bayesian multivariate probit model, we demonstrate a parameter-extended Metropolis-Hastings algorithm for sampling from the posterior distribution of a correlation matrix. Our sampling algorithms lead directly to two readily interpretable families of prior distributions for a correlation matrix. The methodology is illustrated through a simulation study and through an application with repeated binary outcomes on individuals from a study of a suicide prevention intervention.
MINIMAL EXPECTATIONS FOR INCLUSIONS WITH ATOMIC CENTRES

We study the set of minimal conditional expectations for inclusions of von Neumann algebras with atomic centres. Contrary to the case of finite dimensional centres, the set of minimal conditional expectations with scalar index consists, in general, of more than one element. Some calculations relative to the connection between minimal expectations and entropy are also done. The last section is devoted to the existence of conditional expectations preserving a Markov trace. Simple examples show that all possibilities can occur.
Pulsation and mass loss in Mira variables

The behavior of pulsation in the outer layers of a ''typical'' Mira variable (M=M/sub sun/,L=10/sup 4/L/sub sun/, T/sub eff/=2750 K,P=373 days) has been studied in the adiabatic and isothermal limits. A shock wave propagates outward once per period, and the radial velocity obtained from observations of hydrogen emission lines is identified with the velocity of gas in the postshock region. In the adiabatic case, mass loss in the form of a steady stellar wind was produced. However, the behavior of the postshock velocity does not agree well with observations, and the mass loss rate is far too large (0.02M/sub sun/yr/sup -1/) if approximate observational estimates of the photospheric density are adopted. In the isothermal case, no continuous mass loss was produced but occasional ejection of shells occurs. The time-averaged mass loss rate produced by this process is approx.10/sup -12/M/sub sun/yr/sup -1/. The time-dependence and magnitude of the emission line velocity is in reasonable agreement with observations. In a strongly driven model, a type of behavior was found which may explain the alternating high and low minima observed in RV Tauri variable and some Miras (e.g.,R Cen). Pulsation introduced into a star undergoing steady mass loss as a result of radiationmore » pressure acting on grains caused the mass loss rate to increase by a factor of approx.40 while the terminal velocity of the flow was almost unaltered. « less
Nanostructured zinc oxide platform for cholesterol sensor

Nanostructured zinc oxide (nano-ZnO) film has been fabricated onto indium tin oxide (ITO) containing preferred (002) plane and 10 nm crystallite size using sol-gel technique for immobilization of cholesterol oxidase (ChOx). Electrochemical response of ChOx/nano-ZnO/ITO bioelectrode determined as a function of cholesterol concentration using cyclic voltammetry technique reveals improved detection range (5–400 mg/dl), low detection limit (0.5 mg/dl), fast response time (10 s), sensitivity (0.059 μA/mg dl−1 cm−2), and low value (0.98 mg/dl) of Michaelis–Menten constant (Km). It is shown that nano-ZnO film provides better environment and enhanced electron transfer between ChOx and electrode.
Dropout Rates and Response Times of an Occupation Search Tree in a Web Survey

Abstract Occupation is key in socioeconomic research. As in other survey modes, most web surveys use an open-ended question for occupation, though the absence of interviewers elicits unidentifiable or aggregated responses. Unlike other modes, web surveys can use a search tree with an occupation database. They are hardly ever used, but this may change due to technical advancements. This article evaluates a three-step search tree with 1,700 occupational titles, used in the 2010 multilingual WageIndicator web survey for UK, Belgium and Netherlands (22,990 observations). Dropout rates are high; in Step 1 due to unemployed respondents judging the question not to be adequate, and in Step 3 due to search tree item length. Median response times are substantial due to search tree item length, dropout in the next step and invalid occupations ticked. Overall the validity of the occupation data is rather good, 1.7-7.5% of the respondents completing the search tree have ticked an invalid occupation.
Wideband vibration energy harvester with high permeability magnetic material

A vibration energy harvester based on a high permeability cantilever beam was demonstrated, which overcomes the limitation of the existing approaches in output power and working bandwidth. Magnetostatic coupling between the vibrating highly permeable beam and bias magnetic field leads to maximized flux change and large induced voltage. The coexistence of magnetostatic and elastic potential energy results in the nonlinear oscillation with wide bandwidth. The harvester showed a maximum power of 74 mW and power density of 1.07 mW/cm3 at 54 Hz under acceleration of 0.57 g (with g=9.8 m/s2), and bandwidth of 10 Hz (or 18.5% of the operating frequency).
Stability analysis of mean field models described by Fokker‐Planck equations

A mean field model for weakly coupled oscillators is studied that can describe transitions from stationary uniform distributions to traveling wave solutions. The mean field model is reminiscent of a XY model with infinite‐range interactions. A linear stability analysis of the uniform distribution has been carried out by Kuramoto. We show that the stability analysis can also be carried out on the basis of Lyapunov's direct method. In doing so, we illustrate that the correspondence of Lyapunov's direct method and linear stability analysis that is well‐known for deterministic autonomous systems also holds for mean field models.
Distribution of internal strains in nanocrystalline Pd studied by x-ray diffraction

Internal strains in cluster-compacted nanocrystalline Pd (crystallite size 10–20 nm) were studied by means of wide-angle x-ray scattering. The strain- and size-induced broadening of the Bragg diffraction peaks was determined by Hall or Warren–Averbach analyses. The Warren–Averbach analysis indicates a spatial confinement of internal strain fields. This result supports theoretical models according to which the sources of the stresses are located in the interfaces between the crystallites. Indirect further evidence for a stress localization is derived from recent findings on the variation of internal strains and atomic displacements with the crystallite size. In addition, an anisotropy of the line broadening was observed which cannot entirely be attributed to planar defects (maximum concentration 0.04) but indicates enhanced microstrains in the crystallographic 〈100〉 directions compared to the 〈111〉 directions. Based on this strain anisotropy, various distributions of microstresses are discussed taking into.
Statistics on Diffeomorphisms in a Log-Euclidean Framework

In this article, we focus on the computation of statistics of invertible geometrical deformations (i.e., diffeomorphisms), based on the generalization to this type of data of the notion of principal logarithm. Remarkably, this logarithm is a simple 3D vector field, and can be used for diffeomorphisms close enough to the identity. This allows to perform vectorial statistics on diffeomorphisms, while preserving the invertibility constraint, contrary to Euclidean statistics on displacement fields.