Miracle-dz/UniFAR-FTUs huggingface dataset:
Analytical prediction of broadband noise from mini-RPA propellers with serrated edges

This paper is dedicated to the analysis of the broadband noise of an innovative mini-remotely piloted aircraft propeller geometry with straight or serrated edges. New analytical models for predicting the trailing/leading edges noise from airfoils with serrated edges are implemented and applied to propellers using a blade strip approach. These models are assessed by comparison with spectra obtained from time-domain Lattice Boltzmann method simulations. Obtained results showed that the analytical models are able to predict the noise from either straight or serrated propellers with a good accuracy. A parametric study was conducted to predict the noise emitted by propellers featuring sawtooth trailing edge or leading edge serrations with different parameters. It is shown that the best performance in terms of noise reduction is achieved by sharp and deep serrations. The effects of flow conditions on the noise emitted by the serrated propellers are also investigated.
Investigation of Background from the Inter-Spectrometer Penning Trap and Secondary Electron Emission in the KATRIN Experiment

Investigation of Background from the Inter-Spectrometer Penning Trap and Secondary Electron Emission in the KATRIN Experiment Luke Kippenbrock Chair of the Supervisory Committee: Affiliate Assistant Professor Diana S. Parno Department of Physics The KATRIN experiment aims to determine the neutrino mass with unprecedented precision by measuring the tritium β-decay spectrum with a tandem of MAC-E-filter spectrometers. The background rate measured at the β-detector is a crucial parameter affecting the sensitivity of the experiment. The detector energy resolution affects the intrinsic background contribution from the detector system and, therefore, must be well-characterized. Additionally, the increased size of the main spectrometer compared with predecessor experiments necessitates understanding and quantifying various sources of background electrons originating from the spectrometer. Secondary electron emission from the inner spectrometer surface, induced by environmental gamma radiation and cosmic-ray muons, is investigated as a potentially large source of background electrons. A background source unique to the beamline geometry of KATRIN is the inter-spectrometer Penning trap formed during tandem operation of the spectrometers. Detailed measurements and simulations were performed to quantify the background induced by the Penning trap and to confirm the electron-production model. However, by maintaining ultra-high vacuum conditions inside the spectrometers, the effect of the trap on the total background rate is found to be insignificant compared with contributions from other sources.
Robust randomized optimization with k nearest neighbors

Modern applications of machine learning typically require the tuning of a multitude of hyperparameters. With this motivation in mind, we consider the problem of optimization given a set of noisy function evaluations. We focus on robust optimization in which the goal is to find a point in the input space such that the function remains high when perturbed by an adversary within a given radius. Here we identify the minimax optimal rate for this problem, which turns out to be of order [Formula: see text], where [Formula: see text] is the sample size and [Formula: see text] quantifies the smoothness of the function for a broad class of problems, including situations where the metric space is unbounded. The optimal rate is achieved (up to logarithmic factors) by a conceptually simple algorithm based on [Formula: see text]-nearest neighbor regression.
DECAY LENGTH ESTIMATION OF SINGLE-, TWO-, AND THREE-WIRE SYSTEMS ABOVE GROUND UNDER HEMP EXCITATION

We analytically model single-, two-, and three-wires above ground to determine the decay lengths of common and differential modes induced by an E1 high-altitude electromagnetic pulse (HEMP) excitation. Decay length information is pivotal to determine whether any two nodes in the power grid may be treated as uncoupled. We employ a frequency-domain method based on transmission line theory named ATLOG — Analytic Transmission Line Over Ground to model infinitely long and finite single wires, as well as solve the eigenvalue problem of a single-, two-, and three-wire system. Our calculations show that a single, semi-infinite power line can be approximated by a 10 km section of line and that the second electrical reflection for all line lengths longer than the decay length are below half the rated operating voltage. Furthermore, our results show that the differential mode propagates longer distances than the common mode in twoand three-wire systems, and this should be taken into account when performing damage assessment from HEMP excitation. This analysis is a significant step toward simplifying the modeling of practical continental grid lengths, yet maintaining accuracy, a result of enormous impact.
MIMO Beamforming Schemes for Hybrid SIC FD Radios With Imperfect Hardware and CSI

We study a multiple-input multiple-output (MIMO) full-duplex (FD) radio system, aiming to increase the feasibility of this technology in bi-directional communications. In particular, we consider that the FD radios are equipped with the State-of-the-Art (SotA) hybrid SI cancellation (SIC) capabilities, but must cope with hardware (HW) and channel state information (CSI) imperfections, contributing four new MIMO beamforming (BF) schemes for such systems. The first is a transmit (TX) beamforming scheme designed via a Fractional Programming (FP) approach, matched with a minimum mean square error (MMSE) beamformer at the receiver. In this benchmark, the FP-based method, the signal to interference-plus-noise ratio (SINR) constraints are relaxed via the quadratic transform (QT), which allows for the SINR-constrained TX-power minimization problem to be solved using interior point methods. Motivated by the high complexity of the latter, three low-complexity alternatives are then derived, in which power minimization is performed via the Perron–Frobenius (PF) approach, while the TX-BF vectors are obtained, respectively, via direct Gradient Projection (GP), QT-relaxation, and via a Double Rayleigh Quotient (DRQ) reformulation of the original optimization problem. The simulation results confirm the significant gains achieved by all four schemes over the SotA, revealing the GP and DRQ as the overall best alternatives depending on power limitation, and HW/CSI qualities.
Systematic Comparison of Convection-Allowing Models during the 2017 NOAA HWT Spring Forecasting Experiment

The 2016–18 NOAA Hazardous Weather Testbed (HWT) Spring Forecasting Experiments (SFE) featured the Community Leveraged Unified Ensemble (CLUE), a coordinated convection-allowing model (CAM) ensemble framework designed to provide empirical guidance for development of operational CAM systems. The 2017 CLUE included 81 members that all used 3-km horizontal grid spacing over the CONUS, enabling direct comparison of forecasts generated using different dynamical cores, physics schemes, and initialization procedures. This study uses forecasts from several of the 2017 CLUE members and one operational model to evaluate and compare CAM representation and next-day prediction of thunderstorms. The analysis utilizes existing techniques and novel, object-based techniques that distill important information about modeled and observed storms from many cases. The National Severe Storms Laboratory Multi-Radar Multi-Sensor product suite is used to verify model forecasts and climatologies of observed variables. Unobserved model fields are also examined to further illuminate important intermodel differences in storms and near-storm environments. No single model performed better than the others in all respects. However, there were many systematic intermodel and intercore differences in specific forecast metrics and model fields. Some of these differences can be confidently attributed to particular differences in model design. Model intercomparison studies similar to the one presented here are important to better understand the impacts of model and ensemble configurations on storm forecasts and to help optimize future operational CAM systems.
Consistent Coordinate Transformation for Relativistic Circular Motion and Speeds of Light

A world system is composed of the world lines of the rest observers in the system. We present a relativistic coordinate transformation, termed the transformation under constant light speed with the same angle (TCL-SA), between a rotating world system and the isotropic system. In TCL-SA, the constancy of the two-way speed of light holds, and the angles of rotation before and after the transformation are the same. Additionally a transformation for inertial world systems is derived from it through the limit operation of circular motion to linear motion. The generalized Sagnac effect involves linear motion, as well as circular motion. We deal with the generalized effect via TCL-SA and via the framework of Mansouri and Sexl (MS), analyzing the speeds of light. Their analysis results correspond to each other and are in agreement with the experimental results. Within the framework of special and general relativity (SGR), traditionally the Sagnac effect has been dealt with by using the Galilean transformation (GT) in cylindrical coordinates together with the invariant line element. Applying the same traditional methods to an inertial frame in place of the rotating one, we show that the speed of light with respect to proper time is anisotropic in the inertial frame, even if the Lorentz transformation, instead of GT, is employed. The local speeds of light obtained via the traditional methods within SGR correspond to those derived from TCL-SA and from the MS framework.
A Wideband Circularly Polarized Slot Antenna Backed by a Frequency Selective Surface

This paper presents the design of a coplanar waveguide (CPW)-fed single-layer wideband circularly polarized (CP) planar slot antenna backed by a frequency selective surface (FSS). The planar slot antenna is fed with a stub-loaded modified CPW feed line to tune and optimize the impedance bandwidth. The corners of the square slot antenna are perturbed to produce two orthogonal degenerate modes required for a wideband CP operation. The FSS layer is placed under the slot antenna to increase the gain and axial ratio bandwidth. The measured results of the proposed antenna provide an impedance bandwidth of 63.22% and an axial ratio bandwidth of 31.14% with a peak gain of 4.87 dB. The proposed antenna has a simple geometry, a wide CP bandwidth, and a good gain.
Mitigation of Temperature Gradients in the Buffer Tank of a Natural Circulation Loop Simulating Passive Decay Heat Removal in a Pool Type Reactor

Abstract This study considers the decay heat removal through passive systems (i.e., natural convection) in the pool-type experimental reactor MYRRHA (SCK•CEN). The low velocities associated with natural convection may cause a degradation of the thermal mixing in the upper plenum of the reactor: buoyancy dominated phenomena, such as stratification, buoyant jets or convective cells may occur. The large temperature gradients associated with these phenomena may induce thermal loads on the structure, compromising its integrity. The objectives of this work are, in order, (1) achieving an understanding of the fluid mechanics leading to the formation of thermal gradients in the upper plenum and (2) mitigating the temperature gradients the upper plenum’s geometry. The methodology chosen to address the problem is experimental. A ''two-dimensional'' water facility modeling a slab of the reactor's primary loop was designed. Simultaneous measurements of velocity and temperature were performed in the model's buffer tank using thermocouples and innovative optical imaging techniques. It was observed that vertical thermal gradients develop in the tank because of the combined effect of stratification and advection. Important reductions of local gradients were observed when changing porosity and position of upper plenum’s buffer plates.
Pengaruh Sistem Pembayaran Non Tunai Dalam Era Digital Terhadap Tingkat Pertumbuhan Ekonomi Indonesia

Tujuan_mengetahui pengaruh sistem pembayaran non tunai e-money, kartu debet/ATM dan kartu kredit terhadap tingkat pertumbuhan ekonomi Indonesia. Desain/Metode_Menggunakan metode regresi data time series dengan mengestimasi model regresi linear berganda, Uji asumsi klasik, Uji t dan Uji F Temuan_Sistem pembayaran non tunai APMK yang terdiri dari nilai transaksi e-money dan nilai transaksi kartu kredit memiliki pengaruh yang positif dan signifikan terhadap tingkat pertumbuhan ekonomi, sedangkan untuk nilai transaksi kartu debet/ATM berpengaruh negatif dan signifikan terhadap tingkat pertumbuhan ekonomi. Implikasi_ Secara praktik, Bank Indonesia memberikan promosi penggunaan kartu ATM sebaiknya lebih mengarahkan pengguna memanfaatkan fasilitas transfer dan transaksi secara non tunai serta mengurangi nilai penarikan transaksi tunai. Dengan demikian hal ini akan meningkatkan nilai transaksi APMK (Alat Pembayaran Menggunakan Kartu, yang dalam jangka panjang terbukti memiliki kontribusi dalam pensubstitusian transaksi tunai dan pada akhirnya dapat meningkatkan pertumbuhan ekonomi. Secara teoritis, perlu dilakukan penelitian selanjutnya untuk mendapatkan hasil yang lebih akurat dengan metode regresi data time series. Originalitas_Penelitian ini fokus kepada faktor-faktor yang mempengaruhi pertumbuhan ekonomi dalam sistem pembayaran non tunai dengan menggunakan regresi data time series. Tipe Penelitian_Studi Literatur
HERTZ, A SUBMILLIMETER POLARIMETER

We describe a 32 pixel polarimeter, Hertz, for use at the Caltech Submillimeter Observatory. We present polarization maps of the Orion molecular cloud (OMC-1) at 350 μm (46 detections) and 450 μm (19 detections) with 3σ or better statistical significance. The 350 μm polarization ranges from 1.4 to 6.8% with a median value of 3.3%. The position angles are fairly uniform across the souce at an angle of ∼30 degrees (east of north). We describe the design and performance characteristics of the polarimeter and discuss systematic effects due to telescope and instrumental polarization, atmospheric fluctuations, and reference beam flux.
Asymptotic Modeling of Nonlinear Bending and Buckling Behavior of Carbon Nanotubes

The present work investigates the nonlinear bending and buckling behavior of carbon nanotubes (CNTs) using variational asymptotic method. Considering a CNT as a slender beam structure, an asymptotically-correct nonlinear continuum beam model is presented. Through the resulting nonlinear moment-curvature relationship, the model captures the phenomenon of ovalization of the cross sections and local buckling of the CNT, which arises due to their geometrical nature. Further studies are performed in order to explore the effect of CNT wall thickness on the nonlinear bending behavior of the CNT structure. It is shown that the continuum modeling approach can capture the ovalization and further localization of the CNT deformation under bending. The study aims to provide a reduced-order modeling framework analyzing the inherent nonlinearities associated with the geometrical nature of CNTs.
A Miniaturized High-Selectivity Frequency Selective Rasorber Based on Subwavelength Resonance and Interdigital Resonator

A miniaturized high-selectivity frequency selective rasorber (FSR) with subwavelength resonance and interdigital resonator, which exhibits low insertions loss in passband and two high absorption bands at both sides of one passband, is investigated. The FSR consists of a lossless layer and a lossy layer. The lossy layer is made by a periodic arrangement of cross-dipoles with resistive sheets loaded on both sides of the interdigital resonator. The lossless layer is a bandpass, subwavelength resonant, frequency selective surface composed of three layers of metal in the shape of squares and crosses. An equivalent circuit model is proposed to analyze its operating principle. A meandering procedure is used in conjunction with subwavelength resonance and interdigital resonator to achieve miniaturization of the FSR. The unit cell dimensions are $0.087\lambda _{L}\times 0.087\lambda _{L}\times 0.1\lambda _{L}$ ($\lambda _{L}$ being the free-space wavelength at the lowest operating frequency). Additionally, the designed rasorber has the property of high selectivity due to the subwavelength resonance. Under normal incidence, an insertion loss of about 0.21 dB is obtained at 10.25 GHz, the fractional bandwidth for −10 dB reflection is about 94.5%, and the −3 dB transmission relative bandwidth is 15.7%. The FSR shows a stable response over a wide range of incidence angle of 30° for both transverse electric (TE) and transverse magnetic (TM) polarizations. A prototype of designed FSR has been manufactured and measured, showing a reasonable agreement with simulations.
Development of Software Fault Prediction Models using Combined Metrics Approach

The identification of fault-proneness at an early stage of software development is an imperative aspect to consider in order to reduce efforts in maintaining the quality of software products. In the development of a fault prediction model, combination of metrics results in better explanatory power of the model. The metrics used in combination are often interrelated, and do not have an additive effect, therefore the impact of a metric on another i.e. interaction need to be taken into account. We statistically establish the relevance of acknowledging the interaction between metrics. Such an interaction based modeling results into a significant increase in the explanatory power of the corresponding predictive model. However, this further gives rise to the issue of handling an increased number of predictors and evolved nonlinearity due to complex interaction among metrics. Statistical and rule based techniques have been explored to efficiently handle such situations, wherein the dependency between explanatory and response variables is more complicated than a simple linear additive relationship. This work contributes towards the development of an efficient predictive model involving interaction among predictive variables with an abbreviated set of influential terms Acknowledgements It is with immense joy, I thank the support of my supervisors Prof. Yogesh Singh and Prof. Pravin Chandra, who always encouraged me with all their patience and experience. I owe my heartfelt thankfulness to my supervisor Prof. Yogesh Singh for all his valuable inputs throughout my research work. Numerous impressions of his generosity are pleasantly placed in my memory. I attribute the level of my thesis to the encouragement and efforts of Prof. Pravin Chandra. His passion, insight and intellectual rigor were all invaluable (particularly, recognizing my transition into a new field). Thank you, Sir, for holding my hands, when all I wanted was to give up. I would like to quote Mitch Albom in his memoir "Tuesdays with Morrie" here. ". A teacher affects eternity, and never knows when his influence stops. " My sincere thanks to Prof. Navin Rajpal, Ex-Dean (USICT), for allowing me to pursue my research work with a reduced teaching load (Semester break), when this work was taking shape. I would like to acknowledge the faculty members and staff members of USICT for providing all the cooperation and support, over these many years. Heartfelt thanks to Dr. Jose M, Alonso, Associate Researcher (European Centre for Soft Computing, Spain) for providing valued support in making GUAJE operative, which is used in one of the chapters of this thesis. Special thanks to the Editors and anonymous Reviewers of the publications arising from this thesis, who had patiently replied to my frequent inquiries on the "Manuscript Status". Finally, the existent journey is placed in the holy feet of almighty. With Gratitude to the Existence.
Invariant subspaces for positive operators acting on a Banach space with basis

Recently we established several invariant subspace theorems for operators acting on an lp-space. In this note we extend these results from operators acting on an lp-space to operators acting on any Banach space with a (not necessarily unconditional) Schauder basis. For instance, it is shown that if a continuous quasinilpotent operator on a Banach space is positive with respect to the closed cone generated by a basis, then the operator has a nontrivial closed invariant subspace.
Image-based modelling of the skin-friction coefficient in compressible boundary-layer transition

We develop a model of the skin-friction coefficient based on scalar images in the compressible, spatially evolving boundary-layer transition. The images are extracted from a passive scalar field by a sliding window filter on the streamwise and wall-normal plane. The multi-scale and multi-directional geometric analysis is applied to characterize the averaged inclination angle of spatially evolving filtered component fields at different scales ranging from a boundary-layer thickness to several viscous length scales. In general, the averaged inclination angles increase along the streamwise direction, and the variation of the angles for large-scale structures is smaller than that for small-scale structures. Inspired by the coincidence of the increasing averaged inclination angle and the rise of the skin-friction coefficient, we propose a simple image-based model of the skin-friction coefficient. The model blends empirical formulae of the skin-friction coefficient in laminar and fully developed turbulent regions using the normalized averaged inclination angle of scalar structures at intermediate and small scales. The model prediction calculated from scalar images is validated by the results from the direct numerical simulation at two Mach numbers, 2.25 and 6, and the relative error can be less than 15 %.
Fluctuations hydropluviométriques du bassin-versant de l'oued Tafna à Béni Bahdel (Nord-Ouest algérien)

Situe au nord-ouest de l'Algerie, le bassin-versant de la Tafna a Beni Bahdel, d'une superficie de 1 016 km 2, recoit une precipitation moyenne annuelle de 469 mm, calculee sur une periode de 66 annees (1939-1940 a 2004-2005). Ce bassin, a l'instar de l'ensemble de la region Maghrebine, subit depuis quelques decennies une secheresse persistante. Afin de mettre en relief la severite de cette secheresse, on se propose d'etudier les variations des precipitations et des debits specifiques durant la periode sus-citee. Malgre l'existence d'une periode humide entre 1943-1944 et 1974-1975, le bassin-versant enregistre une decroissance pluviometrique grave apres 1974-1975. Ce deficit evalue a 27 % par rapport a la periode humide est responsable d'une baisse d'ecoulement de 69 %. On assiste alors a une predominance de l'evapotranspiration sur les autres termes du bilan hydrologique. Par ailleurs, il s'avere que la periode seche se caracterise par une aptitude au ruissellement superficiel plus importante que la periode humide.