Miracle-dz/UniFAR-FTUs huggingface dataset:
Wavefront sensing for 3D particle metrology and velocimetry

We present the application of wavefront sensing to 3-dimensional particle metrology for measuring the 3-component velocity vector field in a fluid flow across a volume. The technique is based upon measuring the wavefront scattered by a tracer particle from which the 3-dimensional tracer location can be calculated. Using a temporally resolved sequence of 3-dimensional particle locations the velocity vector field is obtained. In this paper we focus on an anamophic technique to capture the data required to measure the wavefront. Data is presented from a reconstruction of the phase of the wavefront as well as from a more pragmatic approach that examines only the defocus of that wavefront. The methods are optically efficient and robust and can be applied to both coherent and incoherent light in contrast to classical interferometric methods. A focus of this paper has been the filtering techniques in order to reliably extract the particle images from the overall image field. The resolution and repeatability of the depth (or range) measurements have been quantified experimentally using a single mode fiber source representing a tracer particle. A first proof of principle experiment using this technique for 3-dimensional PIV on a sparsely seeded gas phase flow is also presented.
Optimization study on a single-cylinder compressed air engine

The current research of compressed air engine (CAE) mainly focused on simulations and system integrations. However, energy efficiency and output torque of the CAE is limited, which restricts its application and popularization. In this paper, the working principles of CAE are briefly introduced. To set a foundation for the study on the optimization of the CAE, the basic mathematical model of working processes is set up. A pressure-compensated valve which can reduce the inertia force of the valve is proposed. To verify the mathematical model, the prototype with the newly designed pressure-compensated intake valve is built and the experiment is carried out, simulation and experimental results of the CAE are conducted, and pressures inside the cylinder and output torque of the CAE are obtained. Orthogonal design and grey relation analysis are utilized to optimize structural parameters. The experimental and optimized results show that, first of all, pressure inside the cylinder has the same changing tendency in both simulation curve and experimental curve. Secondly, the highest average output torque is obtained at the highest intake pressure and the lowest rotate speed. Thirdly, the optimization of the single-cylinder CAE can improve the working efficiency from an original 21.95% to 50.1%, an overall increase of 28.15%, and the average output torque increases also increases from 22.047 5 N • m to 22.439 N • m. This research designs a single-cylinder CAE with pressure-compensated intake valve, and proposes a structural parameters design method which improves the single-cylinder CAE performance.
Distributed Resource Allocation for Multi-Agent Networks

—We present a distributed algorithm for resource allocation problems where each agent computes its optimal resource allocation locally without knowing the resource allocation, objective, and constraints of other agents, guaranteeing the privacy of each agent’s local data and resource allocation. Each agent communicates with its neighbors over a point-to-point communication network to satisfy the coupling constraints on the resource allocations of all agents. Our distributed algorithm, derived from the dual formulation of the problem using the consensus alternating direction method of multipliers, applies to resource allocation problems with both convex equality and inequality coupling constraints. As such, unlike many other distributed resource allocation methods, our distributed algorithm is not limited to problems with afﬁne coupling constraints. In addition, our algorithm does not require a feasible initialization of the resource allocations for convergence to an optimal resource allocation. We demonstrate faster empirical convergence of our distributed algorithm to the optimal resource allocation compared to other distributed resource allocation algorithms, with our algorithm converging in about two orders of magnitudes fewer communication rounds.
A Locally Optimal Seasonal Unit-Root Test

This article proposes a locally best invariant test of the null hypothesis of seasonal stationarity against the alternative of seasonal unit roots at all or individual seasonal frequencies. An asymptotic distribution theory is derived and the finite-sample properties of the test are examined in a Monte Carlo simulation. The author's test is also compared with the Canova and Hansen test. The proposed test is superior to the Canova and Hansen test in terms of both size and power.
Recent Developments in Superconducting Devices

A simple model of the electrical characteristics of thin‐film‐bridge, point‐contact, and tunnel junction Josephson devices is given, along with some comments on their relative performance at very low and at very high frequencies. A particular example is the dc IV characteristic of a point contact at the center of a parallel‐disk microwave cavity. Some recent developments in devices and the application of a point‐contact loop (SQUID) device to magnetocardiography is described.
An Evaluation of Fractal Methods for Characterizing Image Complexity

Previously, we developed an integrated software package called ICAMS (Image Characterization and Modeling System) to provide specialized spatial analytical functions for interpreting remote sensing data. This paper evaluates three fractal dimension measurement methods that have been implemented in ICAMS: isarithm, variogram, and a modified version of triangular prism. To provide insights into how the fractal methods compare with conventional spatial techniques in measuring landscape complexity, the performance of two spatial autocorrelation methods, Moran's I and Geary's C, is also evaluated. Results from analyzing 25 simulated surfaces having known fractal dimensions show that both the isarithm and triangular prism methods can accurately measure a range of fractal surfaces. The triangular prism method is most accurate at estimating the fractal dimension of surfaces having higher spatial complexity, but it is sensitive to contrast stretching. The variogram method is a comparatively poor estimator for all surfaces, particularly those with high fractal dimensions. As with the fractal techniques, spatial autocorrelation techniques have been found to be useful for measuring complex images, but not images with low dimensionality. Fractal measurement methods, as well as spatial autocorrelation techniques, can be applied directly to unclassified images and could serve as a tool for change detection and data mining.
Topological methods employment to nonlinear-system diagnostics and control

The method of minimal embedding dimension definition of the chaotic attractor on the basis of topological structure dynamics analysis of phase trajectories is proposed. It is shown that the suggested method yields reduction of experimental data quantity and computer resources about an order in comparison with traditional methods. This reduction is achieved due to localizing topological analysis of the phase trajectories. The proposed method can be used of investigation of nonlinear dynamical systems with chaotic behavior in technique, biology, medicine.
Theoretical investigation of metallic elliptically periodic structures using Mathieu functions

In this paper, an analysis of elliptical periodic structures composed of metallic wires is presented. The transmission and reflection coefficients of elliptical frequency‐selective surfaces (FSSs) are calculated by expressing the scattered field via Mathieu functions and by using an elliptical‐wave multiple reflections model. It is shown that when the elliptical period and the focus are constant, elliptical periodic surfaces have the same transmission and reflection coefficients. This work has potential applications for designing directive antennas. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 988–992, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21543
Fourier domain low coherence interferometry for detection of early colorectal cancer development in the AOM rat model

We present Fourier domain low coherence interferometry (fLCI) applied to the detection of preneoplastic changes in the colon using the ex-vivo azoxymethane (AOM) rat carcinogenesis model. fLCI measures depth resolved spectral oscillations, also known as local oscillations, resulting from coherent fields induced by the scattering of cell nuclei. The depth resolution of fLCI permits nuclear morphology measurements within thick tissues, making the technique sensitive to the earliest stages of precancerous development. To achieve depth resolved spectroscopic analysis, we use the dual window method, which obtains simultaneously high spectral and depth resolution and yields access to the local oscillations. The results show highly statistically significant differences between the AOM-treated and control group samples. Further, the results suggest that fLCI may be used to detect the field effect of carcinogenesis, in addition to identifying specific areas where more advanced neoplastic development has occurred.
Improved radio tomography of the ionosphere using EUV/optical measurements from satellites

Computerized tomography of the ionosphere employs radio beacons on satellites and ground‐based receivers that measure the integrated electron densities along line‐of‐sight propagation paths. The primary limitation to satellite‐based ionospheric radio tomography is the lack of near‐horizontal ray paths. This restricts the accuracy for the reconstruction of vertical profiles in the F region. Horizontal integration paths may be obtained using the natural extreme ultraviolet emissions in the ionosphere. The emissions at 91.1 nm are the result of radiative recombination of O+ ions and electrons and at 83.4 nm are produced by photoionization of atomic oxygen and subsequent scatter by the atomic oxygen ion. Combining data from radio and EUV measurements yields greatly improved ionospheric density reconstructions. This concept will be tested using the TERRIERS satellite scheduled for launch in early 1998.
Evaluation of Perceptual Hashing Algorithms Against Image Manipulation Over Social Media Platforms

—Perceptual hash is a ﬁngerprint of a multimedia ﬁle derived from features of its content. In defending against image-based fake news, compared with crypto hash, perceptual hash shows its advantage in detecting image manipulation while still being able to identify the same images that have different format or resolutions. However, most of prior perceptual hash research used general image datasets for testing, e.g., CASIA, without considering real application environments. Because of the rampant and serious threat of fake news in social media platforms, in this paper, for the ﬁrst time we evaluate and analyze seven state-of-art perceptual hash algorithms in detecting image manipulation in three major social media platforms: Facebook, Twitter and Instagram. These platforms, like others, utilize different processing on user-uploaded images upon sharing, such as compression, scaling, etc. Our real-world image evaluation and analysis shows the contrast on the three platforms’ image processing and performance comparison of those seven algorithms in detecting image manipulation. Furthermore, we present an approach to ﬁnd the optimal detection threshold for each algorithm when being used for social media platforms.
On the dispersion of a developing droplet spectrum in a turbulent cloud

It is shown that the combined effects of condensation and shear-induced coalescence are able to produce significant dispersion in an initially narrow droplet spectral density centred on a radius of about 10 ? m. Provided that the degree of supersaturation of the ambient air is sufficiently large, the time scale for this dispersion process is small compared with the expected life-time of a cloud. DOI: 10.1111/j.2153-3490.1974. tb01626.x
Observations of magneto‐optic phase contrast using a scanning laser microscope

A scanning laser microscope (SLM) has been built which is capable of observing magnetic structure via ‘‘conventional’’ Kerr imaging techniques and a ‘‘novel’’ magneto‐optic phase contrast approach. This latter contrast mode highlights magnetic transitions, rather than domains themselves. In this paper we present results of observations in TbFeCo samples using this phase contrast technique and assess its possible application as a read‐out mechanism for magneto‐optic recording systems.
Helium ionization driving in Beta Cephei stars.

In a series of nonadiabatic linear pulsation analyses, the destabilizing effect of the He/sup +/ ionization edge (which is responsible for an opacity feature near T=1.5 x 10/sup 5/ K) is demonstrated. This mechanism is shown to be most effective in a region of the H--R diagram nearly coincident with that of the observed . beta. Cephei variables. Although actual instability is not obtained with standard models, it is shown that this could easily be due to approximations in the models and poor opacity resolution above T=10/sup 5/ K. Slightly modified models are presented that do show an instability strip in good agreement with observed . beta. Cepheids.
Stochastic models for the evaluation of magnetisation faults

Purpose – The introduction of stochastic deviations due to production faults into the finite element (FE) simulation of electrical machines requires suitable error-model. These models should describe the occurring deviations from the ideal case. Permanent magnets, which can be used as rotor excitations in synchronous machines (PMSM), are one out of many possible sources for the aforementioned stochastic production variations. Fitting measured magnet variations to simulation models with the aim of describing the occurring production deviations, however, poses a problem due to two reasons: to begin with, only data of measured flux-densities are available. Second, a solution of the inverse problem is required to obtain data about changes inside the magnet. This paper, therefore, presents two solutions to this problem. Design/methodology/approach – Two error-models, one based on knowledge about the magnetisation process, the other one built upon principal component analysis, are presented. Both models are eva.
User's Guide for SOL/NPSOL: A Fortran Package for Nonlinear Programming.

Abstract : This report forms the user's guide of SOL/NPSOL, a set of Fortran subroutines designed to minimize an arbitrary smooth function subject to constraints, which may include simple bounds on the variables, linear constraints and smooth nonlinear constraints (NPSOL may also be used for uncontrained, bound-constrained and linearly constrained optimization.) The user must provide subroutines that define the objective and constraint functions and their gradients. All matrices are treated as dense, and hence NPSOL is not intended for large sparse problems. NPSOL uses a sequential quadratic programming (SQP) algorithm, in which the search direction is the solution of a quadratic programming (QP) subproblem. The algorithm treats bounds, linear constraints and nonlinear constraints separately. The Hessian of each QP subproblem is a positive-definite quasi-Newton approximation to the Hessian of an augmented Lagrangian function. The steplength at each iteration is required to produce a sufficient decrease in an augmented Lagrangian merit function. Each QP subproblem is solved using a quadratic programming package with several features that improve the efficiency of an SQP algorithm.
Ozone signatures of climate patterns over the Euro‐Atlantic sector in the spring

The influence of low‐frequency tropospheric dynamics upon column ozone interannual variability is estimated in the spring season over the Euro‐Atlantic sector. This dynamical variability of tropospheric origin is examined in terms of leading climate patterns, derived from an empirical orthogonal function analysis of the National Center for Environmental Prediction 500 mb geopotential height analyses. In order to fingerprint the spatial and temporal ozone signatures of these patterns, the Total Ozone Mapping Spectrometer satellite observations of column ozone during the last two decades are used. The geographical ozone signatures of these climate patterns are extracted by linear regression and their time evolution reconstructed.
Managing pricing of QoS for service differentiation in wireless networks

In this paper we consider service differentiation in wireless networks using pricing policy. The pricing methodology examined is based on "auctioning" pricing. In the present work, it is applied on IEEE 802.11-based wireless networks. The uplink traffic in an IEEE 802.11 wireless network operating in the PCF mode is considered to be "thin" as the mobile users in the network are subject to power limitations and the biggest volume of traffic occurs on the downlink - from the Base Station to the mobile users. The Base station advertises different levels of Quality of Service (QoS) and the Mobile Users are competing for channel resources by bid requests. Based on the variability of the wireless channel, the amount of the available bandwidth shared between the mobile users changes, the price of the QoS changes as well and the users might change the bids they are offering or change the QoS they request from the Base Station. In the present bidding and pricing scheme, an analytical model for price determination is provided and the results of OPNET based simulations for prove of concept are presented.
An Objective Cyclone Climatology for the Southern Hemisphere

Abstract An objective method is developed and used to derive a climatology of centers of cyclonic vorticity for the Southern Hemisphere, based on twice-daily European Centre for Medium-Range Weather Forecasts (ECMWF) 1000-hPa analyses during 1980–86. These centers were computed as local minima of geostrophic relative vorticity ζg, extending previous studies based on pressure minima. This use of ζg, avoids a bias favoring slower and/or deeper cyclones that occurs when pressure is used and includes a large number of additional mobile vorticity centers in the 45°–55°S band that are missed where a local pressure minimum cannot be found. An automated tracking algorithm similar to that of Murray and Simmonds is used to match predicted location, pressure, and ζg from previous track history with available centers. Large numbers of ζg centers were found south of 60°S and near the midlatitude continents, as in previous studies. These were a mixture of migratory centers and other fixed topographic features. The maxi.
Buckling and postbuckling analyses of laminated anisotropic structures

A review is given of recent advances in two aspects of the numerical simulation of the buckling and postbuckling responses of composite structures. The first aspect is exploiting non-traditional symmetries exhibited by composite structures; and strategies for reducing the size of the model and the cost of the buckling and postbuckling analyses in the presence of symmetry-breaking conditions (e.g. asymmetry of the material, geometry, and/or loading). The second aspect pertains to the prediction of onset of local delamination in the postbuckling range and accurate determination of transverse shear stresses in the structure. The accuracy and effectiveness of the strategies developed are demonstrated by means of a numerical example.
Multiple lateral photo-Dember terahertz emitters illuminated by a cylindrical micro-lens array

We demonstrate a terahertz multiple emitter design based on the lateral photo-Dember effect and illuminated with a cylindrical micro-lens array. The multiple emitter produces an average of 5.2 times the output power of a single lateral photo-Dember emitter and is capable of reaching bandwidth comparable to that of a single commercial photoconductive antenna.
H.264 encoder with low complexity noise pre-filtering

In this paper, an H.264 encoder is proposed which incorporates a noise pre-filter with little additional complexity. The motion estimation process in the H.264 encoder, applied to multiple reference pictures, is re-used for temporal noise filtering. Significant objective and subjective improvement is observed for the proposed system versus a standalone H.264 encoder, with greater improvement at higher bitrates. For sequences with artificially generated noise, average PSNR improvements of 0.46 to 1.96 dB were obtained. The optimum number and type of pictures to use in the temporal noise filter was also studied. The proposed single stage encoder with noise filter system provides only a slight reduction in performance as compared to a more computationally complex two-stage system with separate noise filter and encoder.
Aplicações de redes neurais e previsões de disponibilidade de recursos energéticos solares

This work aims at discussing the artificial neural networks (ANN) and some applications in renewable energy assessment. First, the paper describes the statistical relevance of this tool in different areas of knowledge and the main ANN concepts and configurations. Finally, the paper presents and discusses the use of ANN for the solar energy assessment in Brazil by using data collected in SONDA sites operated by the Center for Earth System Science of the Brazilian Institute for Space Research. The results show that ANN can provide reliable estimates with better performance than other statistical tools.
Monitoring and Maintaining Student Online Classroom Participation Using Cobots, Edge Intelligence, Virtual Reality, and Artificial Ethnographies

In this project Virtual World technology and Edge Intelligence to produce a shared social landscape for the society of learners. The idea is to create a Virtual World in which learners can participate and interact. One that is parallel to the learning environment or classroom. This can be viewed as an online multi-user environment such as “second-life” where on-line learners can interact and construct their own spaces. Their ability to work in that space is governed by input from their robot mentor (Human Robot Learning Unit). Skills in the Classroom Virtual World are provided as a result of a student’s behavior in the learning environment. The Virtual World can persist after the learning session is concluded so it provided an incentive for learners to do well in the learning session so that they can acquire points that translate into skills in the corresponding Virtual World. That Virtual World can be shared by several learning sessions or classes to provide a more comprehensive learning environment. An online ethnography of the interactions of learners and instructors can be produced as suggested by McCarthy and Wright (3).
Growth and Processing of Relaxed-Si1-xGex/Strained-Si Structures for Metal-Oxide Semiconductor Applications

Epitaxial growth and processing issues related to strained-Si metal-oxide semiconductor field effect transistor (MOSFET) fabrication are discussed. The material quality of the graded Ge composition, relaxed- Si1-x Gex buffer layers is analyzed. The ion implants used to form complementary metal-oxide semiconductor (CMOS) “wells” prior to epitaxy are found to degrade the quality of these layers by introducing a high density of misfit dislocation nucleation sites. Rough surface morphology, short misfit dislocation line lengths, and high threading defect densities are correlated with the increased nucleation site density. In addition, the oxidation of strained Si is investigated by Rutherford backscattering and Raman spectroscopy. No measurable strain relaxation is found as a result of thermal oxidation at temperatures up to 850° C.