Miracle-dz/UniFAR-FTUs huggingface dataset:
Nonsinusoidal Path Optimization of a Flapping Airfoil

The path of a flapping airfoil undergoing a combined, nonsinusoidal pitching and plunging motion is optimized for maximum thrust and/or propulsive efficiency. The nonsinusoidal, periodic flapping motion is described using nonuniform rational B splines. A gradient based algorithm is then employed for the optimization of the nonuniform rational B-spline parameters. Unsteady, low speed laminar flows are computed using a Navier-Stokes solver in a parallel computing environment The numerical evaluation of the gradient vector components, which requires unsteady flow solutions, is also performed in parallel. It is shown that the thrust generation may significantly be increased in comparison to the sinusoidal flapping motion. For a maximum thrust generation, the airfoil stays at about a constant angle of attack during the upstroke and the downstroke, and may reach very high effective angle of attack values. The pitching motion mostly occurs at the minimum and maximum plunge positions.
Asymptotic Number of Roots of Cauchy Location Likelihood Equations

How many elements has Rn; how many roots are there? The standard maximum likelihood theory guarantees that one of the elements of Rn-the maximum likelihood estimate-is close to 0, and that all other elements are bounded away in probability as n -X 00 from 0. But it does not tell us how many elements there are. Let rn = card(Rn) be the number of roots. With probability one the likelihood equation has only simple roots, which are alternately local maxima and minima of the likelihood function. Hence rn is odd, there are ? /2(rn + 1) local maxima and 1/2(rn 1) local minima. Of the local maxima, one is the global maximum: the maximum likelihood estimate. Let us call the other local maxima "false maxima". These 1/2(rn 1) false maxima are an embarrassment for the maximum likelihood method of estimation; the following theorem shows that their number is really quite small.
Effect of surfactant on two-layer channel flow

Abstract The effect of insoluble surfactant on the interfacial waves in connection with a two-layer channel flow is investigated for low to moderate values of the Reynolds number. Previous studies focusing on Stokes flow (Frenkel & Halpern, Phys. Fluids, vol. 14, 2002, p. L45; Halpern & Frenkel, J. Fluid Mech., vol. 485, 2003, pp. 191–220) are extended by including the inertial effect and the study of low-Reynolds-number flow (Blyth & Pozrikidis, J. Fluid Mech., vol. 521, 2004b, pp. 241–250) is enlarged up to moderate Reynolds number. Linear stability analysis based on the Orr–Sommerfeld boundary value problem identifies a surfactant mode together with an interface mode. The presence of surfactant on the interfacial mode is stabilizing at high viscosity ratio and destabilizing at low viscosity ratio. The threshold of instability is determined as a function of the Marangoni number. A long-wave model is developed to predict the families of nonlinear waves in the neighbourhood of the threshold of instability. Far from the threshold, wave dynamics is explored under the framework of a three-equation model in terms of lower layer flow rate ${q}_{2} (x, t)$ , lower liquid-layer thickness $h(x, t)$ and surfactant concentration $\Gamma (x, t)$ . Primary instability analysis of a three-equation model captures the result of the Orr–Sommerfeld boundary value problem very well for quite large values of wavenumber. In the nonlinear regime, travelling wave solutions demonstrate deceleration of maximum amplitude and acceleration of speed with the Marangoni number at high viscosity ratio $m\gt 1$ and show completely the opposite behaviour at low viscosity ratio $m\lt 1$ . However, both maximum amplitude and speed attain a fixed value with increasing Reynolds number and this leads to saturation of instability.
Mission Design for the Innovative Interstellar Explorer Vision Mission

The Innovative Interstellar Explorer, studied under a NASA Vision Mission grant, examined sending a probe to a heliospheric distance of 200 Astronomical Units (AU) in a "reasonable" amount of time. Previous studies looked at the use of a near-Sun propulsive maneuver, solar sails, and fission reactor powered electric propulsion systems for propulsion. The Innovative Interstellar Explorer's mission design used a combination of a high-energy launch using current launch technology, a Jupiter gravity assist, and electric propulsion powered by advanced radioisotope power systems to reach 200 AU. Many direct and gravity assist trajectories at several power levels were considered in the development of the baseline trajectory, including single and double gravity assists utilizing the outer planets (Jupiter, Saturn, Uranus, and Neptune). A detailed spacecraft design study was completed followed by trajectory analyses to examine the performance of the spacecraft design options.
Electron densities in Jupiter's outer magnetosphere determined from Voyager 1 and 2 plasma wave spectra

[1] This paper presents an electron plasma density data set for Jupiter's outer magnetosphere derived from high-resolution wideband measurements of low-frequency radio and plasma waves obtained by Voyagers 1 and 2 during their 1979 flybys. This work utilizes a new data processing tool that makes important improvements in the identification of the plasma frequency and other characteristic frequencies of the plasma, thereby allowing for the determination of the electron density within the Jovian magnetosphere. Furthermore, this work includes the interpretation of complex spectra including sometimes overlapping wave phenomena including continuum radiation, Z mode emissions, and whistler mode waves. Using the theory of cold plasmas and measurements of the magnetic field from which the electron cyclotron frequency can be calculated, we establish an extensive set of reasoning for interpreting cutoffs and resonances in the wave spectra to identify characteristic frequencies of the plasma, including the electron plasma frequency, R = 0 cutoff, L = 0 cutoff, and upper hybrid resonance frequency. While most Voyager plasma wave data used are obtained in the plasma sheet where the plasma frequency is greater than the cyclotron frequency, this investigation also analyzes observations in the lobe where the cyclotron frequency is greater than the plasma frequency to interpret the various cutoffs and resonances in the spectrum. The resulting data set for the electron densities has higher temporal resolution than any others that exist today. Also, given the identification of spectral features to accuracies of ∼100 Hz or better, the density measurements are among the most accurate for Jupiter's magnetosphere.
The Turbulent Structure of the Stable, Nocturnal Boundary Layer

Abstract A large number of turbulence observations were made under stable conditions along a meteorological mast at Cabauw, The Netherlands. To present and organize these data we turn to the parameterized equations for the turbulent variances and covariances. In a dimensionless form these equations lead to a local scaling hypothesis. According to this hypothesis, dimensionless combinations of variables which are measured at the same height can be expressed as a function of a single parameter z/Λ. Here, Λ is called a local Obukhov length and is defined as Λ=−τ3/2T/(kgwθ) where τ and wθ) are the kinematic momentum and heat flux, respectively. Note that, in general, Λ may vary across the boundary layer, because τ and wθ are still unknown functions of height. The observations support local scaling. In particular, they agree with the limit condition for z/Λ→∞, which predicts that locally scaled variables approach a constant value. The latter result is called z-less stratification. An important application of z.
On the Spectroscopic Nature of HD 221866

On the basis of a new classification‐resolution spectrum, we find that HD 221866, a member of the newly discovered γ Doradus variable‐star class, is an Am (metallic‐line A‐type) star. Observations with the Cambridge radial‐velocity spectrometer reveal that the star is a double‐lined spectroscopic binary with a period of 135 days and a mass ratio of 1.11 ± 0.03. We have determined the basic physical parameters of both components through spectral analysis of the classification‐resolution spectrum and a medium‐resolution spectrum from the KPNO coudé‐feed spectrograph in conjunction with fluxes from visible spectrophotometry and the TD‐1 satellite. We confirm the results of Fekel et al. that the primary is the Am star, whereas the secondary appears to be a normal early F‐type dwarf. We reanalyze the time‐series photometric data for HD 221866 and confirm the existence of two periods found by Henry & Fekel.
Formation and evolution of the Galactic Bulge and Spheroid: Where did the Spheroid Gas Go?

The chemical abundance distribution of the Galactic spheroid is most simply explained if most - perhaps as much as 90% - of the mass originally associated with the spheroid was removed during the period of star formation. The fate of this gas is largely determined by its angular momentum content and cooling processes. The central Galactic bulge is a likely sink. We discuss several possible models for evolution of the Galactic r 1/4 spheroid and bulge, to investigate how the fate of the missing spheroid mass can be constrained, together with the rate of star formation in the bulge
Effects of the Grain Orientation on the Electrocaloric Effect of Polycrystalline Ferroelectrics

Grain orientation in polycrystalline ferroelectrics has an important effect on the properties of the material, such as the electrocaloric effect (ECE). This paper design a BaTiO3 polycrystalline model including four grains, and the effect of grain orientation difference on the ferroelectricity and ECE of polycrystalline ferroelectrics is studied. The results show that the ferroelectricity of polycrystals gradually weakens with the increase of orientation difference, and with the temperature increases, the ferroelectricity gradually loses. The reduction of the grain orientation difference will produce a large adiabatic temperature change near the Curie-Weiss temperature of BaTiO3, about 5.38 K, meanwhile a negative ECE can be observed, about -2.36 K when the orientation difference reaches 45°. This work shows that regulating grain arrangement can obtain a better mechanical-thermal coupling performance than randomly distributed polycrystalline ferroelectrics.
Origins of radiometric forces on a circular vane with a temperature gradient

Radiometric force on a 0.12 m circular vane is studied experimentally and numerically over a wide range of pressures that cover the flow regimes from near free molecular to near continuum. In the experiment, the vane is resistively heated to about 419 K on one side and 394 K on the other side, and immersed in a rarefied argon gas. The radiometric force is then measured on a nano-Newton thrust stand in a 3 m vacuum chamber and compared with the present numerical predictions and analytical predictions proposed by various authors. The computational modelling is conducted with a kinetic approach based on the solution of ellipsoidal statistical Bhatnagar–Gross–Krook (ES-BGK) equation. Numerical modelling showed the importance of regions with elevated pressure observed near the edges of the vane for the radiometric force production. A simple empirical expression is proposed for the radiometric force as a function of pressure that is found to be in good agreement with the experimental data. The shear force on the lateral side of the vane was found to decrease the total radiometric force.
Acoustoelastic Effect Analysis of Lamb Wave Based on Finite Element Simulation

Stress characterization is an important basis for quality assessment of key structural components. Therefore, to ensure quality and safety, a non-destructive stress monitoring method is urgently needed. The stress monitoring method based on acoustoelastic of Lamb waves has attracted more and more attention due to the wide interrogation region and high detection efficiency. However, the complex dispersion and multi-modal characteristics of Lamb waves make the influence of stress on Lamb wave not well understood. Here, the numerical simulations based on eigenfrequency analysis are adopted to evaluate the stress monitoring ability of Lamb waves, including the establishment of dispersion curve in prestressed waveguide structure and stress sensitivity analysis of different modes of Lamb waves. The results show that the stress sensitivity of S0 mode is higher than that of A0 mode, and the sensitivity varies significantly at different frequencies. In actual applications, the local optimal excitation frequency should be made according to the structure size and boundary conditions.
Interface states and depletion-induced threshold voltage instability in organic metal-insulator-semiconductor structures

We present results obtained from a study of the admittance of metal-insulator-semiconductor capacitors formed from regioregular poly(3-hexylthiophene). Data obtained over a range of applied bias and frequency can be explained by the presence of a distribution of trapping states at the insulator∕semiconductor interface as observed in metal-oxide-silicon capacitors. We also observe a depletion-bias instability in the threshold voltage, VT, that is consistent with negative charge trapping at the insulator∕polymer interface. The shift can be relaxed by illumination with bandgap light, λ=550nm, suggesting that the instability arises from an electronic process.
SIVD: Dataset of Iranian Vehicles for Real-Time Multi-Camera Video Tracking and Recognition

In this paper, a new publicly available 1 web-Scraped Iranian Vehicle Dataset (SIVD) for simultaneous real-time vehicle tracking and recognition is proposed. The datasets provided for Iranian cars in the literature have two fundamental problems. First, the lack of images from different angles, and second, the small number of classes compared to the dispersion of car models in the real world. Therefore, for the purposes of this paper, Iranian vehicle images from car sales websites are collected, and the SIVD dataset is proposed which contains 29 classes and 36,705 images. This paper aims at developing a classification network for Iranian vehicle recognition and implement a real-time tracking system using the YOLOv5 network to perform real-time vehicle model recognition and tracking tasks simultaneously. The ResNet50 achieved an accuracy of 99.29%, the highest among the investigated classification networks.1https://github.com/Farbod-Siahkali/Iranian-Vehicle-Tracking-and-Recognition
Hard Contrastive Learning for Video Captioning

Maximum likelihood estimation has been widely adopted along with the encoder-decoder framework for video captioning. However, it ignores the structure of sentences and restrains the diversity and distinction of generated captions. To address this issue, we propose a hard contrastive learning (HCL) method for video captioning. Specifically, built on the encoder-decoder framework, we introduce mismatched pairs to learn a reference distribution of video descriptions. The target model on the matched pairs is learned on top the reference model, which improves the distinctiveness of generated captions. In addition, we further boost the distinctiveness of the captions by developing a hard mining technique to select the hardest mismatched pairs within the contrastive learning framework. Finally, the relationships among multiple relevant captions for each video is consider to encourage the diversity of generated captions. The proposed method generates high quality captions which effectively capture the specialties in individual videos. Extensive experiments on two benchmark datasets, i.e., MSVD and MSR-VTT, show that our approach outperforms state-of-the-art methods.
Static and dynamic behavior of a porous solid saturated by a two‐phase fluid

A method is presented to determine the elastic constants for an isotropic, porous, elastic solid saturated by a two‐phase fluid. Assuming that the shear modulus of the empty matrix is known, it is shown that the six additional coefficients in the stress–strain relations can be uniquely determined by performing two ideal experiments referred to as ‘‘generalized jacketed and partially jacketed compressibility tests,’’ in analogy with the single‐phase theory of Biot. Under reasonable assumptions on the behavior of the material, the experiments yield expressions for the coefficients in terms of the material properties of the individual phases and the capillary pressure function relating the pressures in the two fluid phases. Finally, numerical results showing properties of the phase velocities and attenuations for the four different types of body waves are presented and analyzed.
VINS-Mask: A ROI-mask Feature Tracker for Monocular Visual-inertial System

Feature tracker is usually believed to be one of the most important components to the performance influence on a Visual-inertial System (VINS). This paper proposes the VINS-Mask scheme, a more robust feature tracker for monocular VINS through Region of Interest (ROI) masks. It could achieve real-time feature tracking with high accuracy and robustness. Firstly, we propose an edge mask to generate the edge-sensitive feature candidate regions from the incoming image frame. Next, we design an interest point sensitive SuperPoint mask with deep learning framework to obtain repeatable and reliable feature candidate regions. We also dynamically adjust the inflation radius by monitoring the initial status from VINS Initialization module to obtain more accurate ROI masks. Notably, compared with the best baseline approach (i.e., VINS-Mono), our VINS-Mask scheme achieves an average improvement accuracy of 0.068m on the dataset of EuRoc drone. After paper publication, our source codes will be available at https://github.com/sunjia-yuanro/VINS-Mask.git.
Ultrafast compound imaging for 2D displacement vector measurements: application to transient elastography and color flow mapping

This paper presents a new technique for 2D imaging of the two-dimensional motion vector at a very high frame rate with ultrasound. Its potential is experimentally demonstrated for transient elastography. To date, only axial displacements induced in human tissues by low frequency vibrators were measured. This new technique allows us to follow both axial and lateral displacements during the shear wave propagation and thus should improve the Young's modulus image reconstruction. The process is a combination of several ideas well known in ultrasonic imaging: ultra-fast imaging, multi-synthetic aperture beamforming, 1D speckle tracking and compound imaging. Classical beamforming in the transmit mode is here replaced by a single plane wave illumination. The beamforming process is achieved only in the receive mode on two independent subapertures. Comparison of successive frames by a 1D speckle tracking algorithm allows to estimate displacements along two different directions linked to the sub-apertures beams. The variance of the deduced estimates is finally improved by tilting the emitting plane wave at each illumination. Beyond transient elastography, this technique could be of great interest for complex flows imaging.
Dual-Core mm-Wave VCO with Enhanced Second Harmonic Extraction by Mode Separation

The voltage-controlled oscillator is the heart of every mm-wave radar or communication system and it needs to attain stringent requirements such as low phase noise and a wide tuning range. In this work, we extend our previous work on dual-core VCO by proposing an enhanced common-mode coupling device for the second harmonic extraction from the VCO resonator using the mode separation principle. he proposed coupling device targets the elimination of eddy currents to reduce power losses and ensure better phase noise. The proposed VCO in measurements exhibits the phase noise of -105.72dBc/Hz at lMHz offset from a 58 GHz carrier and a -ldBm of the output power spectrum. It was tunable up to the tuning range of 26.41 % centered at 58.48 GHz frequency. The VCO along with the butter and 4-stage divide-by-8 fundamental frequency divider consume 112mA from a 1. 8V supply.
A Heuristic Intrusion Detection Approach Using Deep Learning Model

With the widespread usage of networking technology, Intrusion Detection System (IDS) attempts to identify and notify the users as normal or abnormal networking activities. In the wireless network systems, communication is via broadcast network packets. Black hat actors will attempt to compromise or cripple systems using wirelessly communicated packets. This paper proposes a heuristic approach to use a Deep Learning or Deep Neural Network (DNN) to evaluate the risk of intrusion from a given received network packet. The emphasis is on how a DNN can facilitate effective IDS with learning capability to accurately detect new or zero-day network behavior features and then rejecting the network intruder and reduce the risk of the network security. To demonstrate the effectiveness of the DNN model, we used CICIDS2018 dataset and support detection of eight behavioral issues in a network. The result of our IDS system achieved an accurate detection rate of 97% using 80% of the data.
Measurement of Sub-GHz Band LPWA Radiowave Propagation on Each Floor in Indoor Environment

This study investigates the detailed radiowave propagation characteristics of sub-GHz band low-power wide-area (LPWA) communications in an indoor environment. Experiments are carried out in a five-storied reinforced concrete building. LPWA radiowave propagation is measured in the indoor environment, and the effect of such a part of the building on the LPWA radiowave propagation is discussed. The experimental results indicate that the part of the building such as the wall, affects the characteristics of the LPWA radiowave propagations.
SO(3) Rotation Equivariant Point Cloud Completion using Attention-based Vector Neurons

Conventional point cloud completion approaches seldom consider object poses when generating shapes, which could make their networks be vulnerable to pose variations. A possible solution, rotation augmentation in training, would degrade prediction accuracy and cannot essentially ensure output stability over different poses. Therefore, in this paper, we introduce a new generative network that is equivariant-by-construction on SO(3) rotation group. It restores complete shapes following the coarse-to-fine fashion with attention-based vector neurons. We design several modules in our network: a Dynamic Projection Kernel to predict spatial points based on constrained projections on three dynamic coordinates, a Transformer-based Structure Awareness module to analyze local structures, a Local Geometry Propagation Pipeline to extract and fuse point-wise features, and an equivariant Folding Kernel to refine and upsample coarse point clouds. Compared with existing approaches, our network achieves competitive performances on both synthetic and real-world objects1.
Closed-loop Individual-specific EEG Neurofeedback for Emotion Regulation

Individual difference is the main factor affecting the effect of emotion regulation neurofeedback training. An individual-specific emotion recognition model can be constructed based on machine learning. However, the current researches simply the preprocessing process to meet real-time feedback, resulting in a reduction in classification accuracy. This paper proposes a closed-loop electroencephalogram (EEG) neurofeedback processing program with high accuracy in feedback information. Artifact subspace reconstruction is used to optimize EEG processing. The positive, neutral, and negative emotion topographic maps of the 5 frequency bands verify inter-individual differences. A support vector machine with particle swarm optimization is used to construct an individual emotion recognition model based on the power spectral density features. The average classification accuracy of 5 subjects is 97.49%. The emotion facial Go/No-go task objectively demonstrates the effectiveness of neurofeedback training on emotion regulation. The closed-loop individual-specific EEG neurofeedback program provides a promising method for emotion regulation training.