Miracle-dz/UniFAR-FTUs huggingface dataset:
Shift- and scale-invariant anamorphic Fourier correlator

A new method of shift- and scale-invariant matched filtering in an anamorphic image processor is proposed. It consists in matching the nonsymmetrical Fourier spectrum of an analyzed scene with the symmetrical filter of a target through a wedge mask. A scene object is transformed with two cylindrical lenses of focal lengths fx and fy > fx in the x and y directions, respectively. In the Fourier plane of the correlator a classical Vander Lugt matched filter is placed, which has been prepared for a basic-sized target by means of a spherical lens of focal length f = fx. The spectrum for a basic-sized target in the analyzed scene perfectly matches the filter along the x axis. The spectrum of a similar object, which is magnified by a factor S = fy/fx, perfectly matches the filter along the y axis. For similar objects of intermediate sizes matched filtering occurs along intermediate directions. Results of the computer experiment are presented, and limitations of the method are discussed.
Coupled Vortex Equations on Complete Kähler Manifolds

Abstract In this paper, we first investigate the Dirichlet problem for coupled vortex equations. Secondly, we give existence results for solutions of the coupled vortex equations on a class of complete noncompact Kähler manifolds which include simply-connected strictly negative curved manifolds, Hermitian symmetric spaces of noncompact type and strictly pseudo-convex domains equipped with the Bergmann metric.
In situ measurement technique for compressional wave velocity dispersion

Marine sediments can be considered a two‐phase medium composed of solid sediment particles and fluid‐filled interstices. Many theories of propagation through such an assemblage predict a dispersive compressional wave velocity. Granular sediments (i.e., sands and gravels) have been predicted and reported to exhibit velocity dispersion and/or a nonlinear frequency‐dependent attenuation in the frequency range 102−104 Hz (Kramers–Kronig relations require velocity dispersion if a nonlinear frequency‐dependent attenuation is observed). One of the experimental challenges has been to measure velocity over several decades of frequency using a single technique so that observed velocity changes cannot be due to different biases in the measurement techniques. A simple in situ measurement technique is described that measures the critical angle as a function of frequency from ∼102−104 Hz and thus infers the velocity dispersion over that band. Measurements on the mid to outer continental shelf (Malta Plateau and the New.
Momentum and thermal transport in neutral‐beam‐heated tokamaks

The relation between momentum and thermal transport in neutral‐beam‐heated tokamaks with subsonic toroidal rotation velocity has been investigated. A theory of diffusive momentum transport driven by ion‐temperature‐gradient‐driven turbulence (ηi turbulence) is presented. In addition, the level of ηi turbulence is enhanced by radially sheared toroidal rotation. The resulting ion shear viscosity is χφ=1.3{(1+ηi)/τ+[(Ln/2cs) (dV0/dr)]2}2(ρ2scs/ Ls). The associated ion thermal diffusivity, χi, is identical to χφ. Thus a scenario based on velocity‐shear‐enhanced ηi turbulence is consistent with the experimentally observed relationship between thermal and momentum confinement.
Aerodynamic design and optimization in one shot

This paper describes an efficient numerical approach for the design and optimization of aerodynamic bodies. As in classical optimal control methods, the present approach introduces a cost function and a costate variable (Lagrange multiplier) in order to achieve a minimum. High efficiency is achieved by using a multigrid technique to solve for all the unknowns simultaneously, but restricting work on a design variable only to grids on which their changes produce nonsmooth perturbations. Thus, the effort required to evaluate design variables that have nonlocal effects on the solution is confined to the coarse grids. However, if a variable has a nonsmooth local effect on the solution in some neighborhood, it is relaxed in that neighborhood on finer grids. The cost of solving the optimal control problem is shown to be approximately two to three times the cost of the equivalent analysis problem. Examples are presented to illustrate the application of the method to aerodynamic design and constraint optimization.
Additive Manufacturing from a Biomedical Perspective

This work aims to present a global view of additive manufacturing, focused in biomedical area. With the evolution of technology, there has been an increasing demand for customized products, which has intensified the need for alternative manufacturing techniques. Additive manufacturing (AM) consists in the development of physical models through the deposition of layer-by-layer material from three-dimensional virtual models. About three decades ago, Fusion Deposition Modeling (FDM) technology was developed. FDM is an AM material extrusion technology, in which the material used is extruded by a nozzle. FDM has been growing, as well as the equipment and software involved, to broad applications in the field of biomedical engineering, such as the development of personalized and functional medical devices (including stents). This study presents the state of the art of 3D printing and additive manufacturing, as well as their techniques, obstacles and innovations. In addition, a stent was developed through a CAD software and it was manufactured through a 3D FDM printer using PLA.
Electro-optic and Piezoelectric Coefficients and Refractive Index of Gallium Phosphide

Measurements of the constant‐strain electro‐optic coefficient of GaP between 0.56 and 3.39 μ wavelength were made using both pulsed electric field and optical heterodyne techniques. At 0.6328 μ wavelength its value is −0.97×10−12 m/V. A dispersion of only 10% is present between 0.56 and 3.39 μ. Approximate values of the piezoelectric coefficient and the constant‐stress electro‐optic coefficient are also obtained from the analysis of the experiments. For GaP the magnitude of the constant‐stress coefficient is less than the constant‐strain coefficient. The analysis also points out an often ignored effect: electro‐optic measurements made with electric field frequencies in the range of resonant acoustic frequencies may not exhibit the expected symmetry of the crystal plus field but may also evidence effects from the crystal shape. Accurate refractive index measurements made on many GaP crystals between 0.545 and 0.70 μ wavelength are also reported.
A generalized block truncation coding algorithm for image compression

Block Truncation Coding is a recently developed approach to image compression whose design is specified by the appropriate moment preserving quantizer. In this paper we show how the basic Block Truncation Coding algorithm can be generalized to include a family of moment preserving quantizers with the potential for improved performance. We then illustrate by way of example that such improvement is indeed possible from the standpoint of peak signal to noise ratio. There is a subclass of this family of moment preserving quantizers for which practical difficulties in implementation exist; however, we show that frequently we can avoid this subclass and still obtain good performance.
Reflection and transmission of obliquely incident electromagnetic waves by an inhomogeneous plasma slab moving parallel to the magnetostatic field

The problem of the reflection and transmission of obliquely incident electromagnetic waves by an inhomogeneous plasma slab moving parallel to the magnetostatic field is discussed. For the analysis of the problem, an inhomogeneous plasma slab is subdivided into a number of thin homogeneous layers, and the easier problem of the reflection and transmission by the stratified plasma slab is solved instead of directly treating the wave equations for an inhomogeneous plasma slab. For linear and parabolic electron density profiles, the reflection properties of the moving inhomogeneous magnetoplasma slab are investigated quantitatively with the aid of numerical examples.
A Random Walk through the Field of Speckle

Tne salient features of "classical" speckle patterns are reviewed. The relaxation of assumptions leading to the classical model yields statistical properties that differ from those associated with conventional speckle. Attention is turned to a summary of those new statistical aspects of speckle that have been discovered or explored since the last SPIE conference on speckle, held in August of 1990.
Care Robot Transparency Isn't Enough for Trust

A recent study featuring a new kind of care robot indicated that participants expect a robot's ethical decision-making to be transparent to develop trust, even though the same type of ‘inspection of thoughts’ isn't expected of a human carer. At first glance, this might suggest that robot transparency mechanisms are required for users to develop trust in robot-made ethical decisions. But the participants were found to desire transparency only when they didn't know the specifics of a human-robot social interaction. Humans trust others without observing their thoughts, which implies other means of determining trustworthiness. The study reported here suggests that the method is social interaction and observation, signifying that trust is a social construct. Moreover, that ‘social determinants of trust’ are the transparent elements. This socially determined behaviour draws on notions of virtue ethics. If a caregiver (nurse or robot) consistently provides good, ethical care, then patients can trust that caregiver to do so often. The same social determinants may apply to care robots and thus it ought to be possible to trust them without the ability to see their thoughts. This study suggests why transparency mechanisms may not be effective in helping to develop trust in care robot ethical decision-making. It suggests that roboticists need to build sociable elements into care robots to help patients to develop patient trust in the care robot's ethical decision-making.
Functional brain imaging by multi-wavelength time-resolved near infrared spectroscopy

We present a description of evolution of time-resolved systems developed at the Department of Physics, Politecnico di Milano for tissue oximetry and functional brain imaging. From a single source and 4-channel set-up we have upgraded to a potentially 18-sources and 64-channel device. An example of sensitivity of the latest set-up is reported for a motor task experiment. A short discussion on the next generation time-resolved instrumentation for functional studies is also presented.
Gabor phase based gait recognition

An effective gait recognition approach based on the gait energy image (GEI) representation is proposed. Synthetic GEIs are first created to address the problem of lacking training data. Then the Gabor phase spectrum of the GEI which was ignored in previous works is utilised as an input feature, and it is subsequently projected into a low dimensional space by linear discriminant analysis to perform classification. Experimental results show that the proposed approach outperforms other algorithms in terms of recognition accuracy.
FLUID BEHAVIOUR OF SIDE-BY-SIDE CIRCULAR CYLINDERS IN STEADY CROSS-FLOW

Abstract The flow field for two and three circular cylinders of equal diameter D arranged in a side-by-side configuration in steady cross-flow was investigated using flow visualization, hot-film anemometry and particle image velocimetry (PIV), for centre-to-centre pitch ratios from T / D =1·0 to 6·0, and Reynolds numbers from Re=500 to 3000. For two-cylinder arrangements, three basic flow patterns were observed: single bluff-body vortex shedding at small T / D , biased flow with synchronized vortex shedding at intermediate T / D , and symmetric flow with synchronized vortex shedding at larger T / D . For three-cylinder arrangements, either single bluff-body behaviour or an asymmetric biased flow pattern could be observed at small T / D , whereas a symmetric-biased flow pattern was found at intermediate T / D . Instantaneous representations of the in-plane vorticity field obtained from the PIV technique revealed some variation in these basic flow patterns at given T / D and Re.
Isotropic scaling iterative closest point algorithm for partial registration

The problem of partial registration of isotropic scaling point sets with outliers including noises and missing data is discussed. To solve this problem, a novel objective function based on bidirectional distance is proposed by introducing an overlapping percentage and a scale factor. Furthermore, a novel isotropic scaling iterative closest point (ICP) algorithm is proposed which can compute the scale transformation, the correspondence and the overlapping percentage automatically at each iterative step. Experimental results demonstrate that the algorithm is more robust and precise than the traditional ICP and the state-of-the-art algorithms.
Decentralized Load Estimation for Distribution Systems Using Artificial Neural Networks

In this paper, we present a decentralized load estimation approach to support real-time volt/var optimization in distribution networks with high penetration of distributed generation. The decentralized load estimation scheme relies on local information and on a limited amount of information from neighbor areas. We defined a procedure for measurement selection and feeder partitioning so as to limit communication needs and allow prioritizing the estimation accuracy for selected loads. The measurement selection and feeder partitioning methods are based on the mutual information and minimum-redundancy-maximum-relevance concepts. We tested the proposed approach with a modified radial IEEE 34-node test feeder and a weakly meshed IEEE 123-node test feeder. The effectiveness of the method is validated using a hardware-in-the-loop simulation platform.
Extragenital Screening Is Essential for Comprehensive Detection of Chlamydia trachomatis and Neisseria gonorrhoeae in the Pediatric Population

Chlamydia trachomatis and Neisseria gonorrhoeae are the two most common causes of sexually transmitted disease in the United States. Studies in adults, mostly in men who have sex with men, have shown that the prevalence of C. trachomatis and N. gonorrhoeae infections is much higher in extragenital sources compared to urogenital sources. ABSTRACT Chlamydia trachomatis and Neisseria gonorrhoeae are the two most common causes of sexually transmitted disease in the United States. Studies in adults, mostly in men who have sex with men, have shown that the prevalence of C. trachomatis and N. gonorrhoeae infections is much higher in extragenital sources compared to urogenital sources. A similar large sample of data on the burden of C. trachomatis and N. gonorrhoeae infections by anatomic site is lacking in children. We retrospectively analyzed data from 655 patients tested for C. trachomatis (887 specimens) and N. gonorrhoeae (890 specimens) at the Children’s Hospital of Philadelphia. We restricted the analysis to include patients between 2 and 17 years of age that had all three sources (urine, oropharynx, and rectum) collected at the same visit. The final data set included specimens from all three sources from 148 and 154 patients for C. trachomatis and N. gonorrhoeae, respectively. Specimens were tested for C. trachomatis and N. gonorrhoeae using a Gen-Probe Aptima Combo 2 assay. The burden of C. trachomatis and N. gonorrhoeae infection was significantly higher in the 14- to 17-year age group (24.7%, P = 0.041; 25.8%; P = 0.001) compared to the 10- to 13-year (5.9%; 5.6%), 6- to 9-year (4.6%; 4.6%), and 2- to 5-year (8.3%; 0%) age groups, respectively. The positivity rate for C. trachomatis was highest for rectal (16.2%), followed by urine (5.4%) and oropharyngeal (0.7%) sites. The positivity rate for N. gonorrhoeae was highest for rectal sites (10.4%), followed by oropharyngeal (9.7%) and urine (1.9%) sites. The source with highest diagnostic yield is rectum for C. trachomatis and rectum and oropharynx for N. gonorrhoeae. Hence, extragenital screening is critical for the comprehensive detection of C. trachomatis and N. gonorrhoeae in the pediatric population.
Polarimetric backscatter from fresh and metamorphic snowcover at millimeter wavelengths

This paper presents 35, 95, and 225 GHz polarimetric radar backscatter data from snowcover. It compares measured backscatter data with detailed in situ measurements of the snowcover including microstructural anisotropies within the snowpack. Observations of backscatter mere made during melt-freeze cycles, and measurable differences in the normalized radar cross section between older metamorphic snow and fresh low-density snow were observed. In addition, these data show that the average phase difference between the copolarized terms of the scattering matrix, S/sub vv/and S/sub hh/, is nonzero for certain snow types. This phase difference was found to be related to snowpack features including anisotropy, wetness, density, and particle size. A simple backscatter model based on measured particle size and anisotropy is found to predict the Mueller matrix for dry snowcover with reasonable accuracy.
On least‐squares identification of stochastic linear systems with noisy input–output data

In a recent paper, two least-squares (LS) based methods, which do not involve prefiltering of noisy measurements or parameter extraction, are established for unbiased identification of linear noisy input–output systems. This paper introduces more computationally efficient estimation schemes for the measurement noise variances and develops a new version of two LS based algorithms in combination with the bias correction technique. The proposed two algorithms work directly with the underlying noisy system, thereby being substantially different from the previous methods that need to actually identify an augmented system. It is shown that a significant saving in the computational cost can be achieved by this better way of implementation of the two LS-based algorithms while at almost no sacrifice of the parameter estimation accuracy. The performance of the proposed two identification algorithms and comparisons with their predecessors are substantiated using simulation data. Copyright © 1999 John Wiley & Sons, Ltd.
Metamaterial-Based Pattern-Switchable Linear Array for 2-D Discrete Beam-Scanning Using Hybrid Digital Coding Method

A new low-cost, pattern-switchable, metamaterial-inspired, dielectric resonator (DR) 1-D linear array for 2-D beam-steering is presented by using a hybrid digital coding method. By loading the metasurface on the DR, a low-profile DR radiator is developed. To realize both phase and pattern digital coding, a beam-switching metasurface-loaded 1 bit DR antenna is explored by using a symmetrical feeding scheme and a Yagi-like endfire radiation mechanism. The novel hybrid digital coding method is realized by using p-i-n diodes to co-control the phase (1 bit, 0°/180°) and radiation states (three-beam). Based on the hybrid digital coding method, the developed 1-D linear array creatively achieves low-cost quasi-2-D discrete beam scanning. The pattern reconfiguration technique contributes to the E-plane beam scanning, while the H-plane beam steering is attributed to the phase digital coding sequence. To validate this working mechanism, a four-element linear array is implemented and tested. The realized overlapped −10 dB impedance bandwidth is about 17.6% (covering LTE B42/43 bands), and the realized peak gain is 9.05 dBi. By controlling the switch states of 16 p-i-n diodes, the proposed four-element linear array achieves digital 2-D beam steering (12 beams). The presented antenna features a miniaturized size, wideband, low cost, and good 2-D beam-steering capacity. It provides a new and feasible solution for low-cost 2-D beam scanning, demonstrating a good application potential for intelligent communication systems and low-cost arrays.
Study on Memristor-Based 3-D Convolutional Neural Network Adapting to Non-Ideal Effects

Memristor-based neural network (MNN) has made breakthroughs in image classification, but for complex video recognition, the required deep MNN will inevitably be more sensitive to non-ideal effects. In this work, we evaluate a memristor-based 3-D convolutional neural network (CNN) for action recognition and incorporate various non-ideal effects at the circuit and device level. Hardware-friendly schemes such as time division multiplexing (TDM) and updating with increasing thresholds are also described. Furthermore, a strategy combining forward averaging and mapping back is proposed to alleviate the IR drop effect. By setting the intersection conductance as the differential reference, deep MNNs are able to adapt to the updating asymmetry. Under the above adaptive strategies and in situ training, the network achieves an accuracy of 92.9% higher than the software and requires fewer updating pulses.
Continuous Estimation of Lower Limb Joint Angles From Multi-Stream Signals Based on Knowledge Tracing

Multi-stream signals are increasingly being used in robot-assisted rehabilitation training, where the timely and accurate prediction of a patient's motor intentions is frequently required to provide simultaneous and proportional control strategies. However, existing methods for motion intent prediction typically isolate signals from different modalities, resulting in a loss of signal traceability and interpretability. Therefore, we propose a multi-stream signal-fusion strategy based on knowledge tracing (MSKT). First, we collected surface electromyography, force myography, and vibroarthrography signals from the lower extremity and used different encoders to map these signals into a problem component, concept component, and identity token component. The process of human learning was then simulated using a knowledge-tracing strategy to reconstruct these components into new features. Finally, the reconstructed set of depth features was mapped to joint angles. We validated the performance of the proposed method using motion data from eight participants in different locomotion modes and compared the results to those of a temporal convolution network and long short-term memory networks. The results indicate that the MSKT achieves the lowest root-mean-squared error. This study demonstrates that the proposed knowledge-tracing-based strategy enables accurate continuous estimation for lower-limb exoskeleton rehabilitation robots.
A Note on Downdating the Cholesky Factorization

We analyse and compare three algorithms for “downdating” the Cholesky factorization of a positive definite matrix. Although the algorithms are closely related, their numerical properties differ. Two algorithms are stable in a certain “mixed” sense while the other is unstable. In addition to comparing the numerical properties of the algorithms, we compare their computational complexity and their suitability for implementation on parallel or vector computers.
Enhanced reconstruction in magnetic particle imaging by whitening and randomized SVD approximation

Magnetic particle imaging (MPI) is a medical imaging modality of recent origin, and it exploits the nonlinear magnetization phenomenon to recover a spatially dependent concentration of nanoparticles. In practice, image reconstruction in MPI is frequently carried out by standard Tikhonov regularization with nonnegativity constraint, which is then minimized by a Kaczmarz type method. In this work, we revisit two issues in the numerical reconstruction in MPI in the lens of inverse theory, i.e. the choice of fidelity and acceleration, and propose two algorithmic tricks, i.e. a whitening procedure to incorporate the noise statistics and accelerating Kaczmarz iteration via randomized SVD. The two tricks are straightforward to implement and easy to incorporate in existing reconstruction algorithms. Their significant potentials are illustrated by extensive numerical experiments on a publicly available dataset.