Miracle-dz/UniFAR-FTUs huggingface dataset:
Generating Proton Energy Spectra for Space Environment Tests with Laser Driven Accelerators (September 2021)

Conventional accelerators can produce monoenergetic particles to perform radiation tests for electronic components and materials, which are used in space. All components must be tested by several particle beams with different energies in the range of that it will be subjected to in space, which increase the cost to determine the radiation hardness of these components. Therefore, this is a difficult scenario to mimic with conventional accelerators [1]. Fortunately, laser driven accelerators (LDAs) are capable of robust generation of particle beams composed of electrons, protons, neutrons, and ions, as well as photons. Wide range and energy of particles can be produced simultaneously from this system and can mimic the space radiation environment. By using LDA systems, the impact of space radiation on space electronics can be tested in a small laboratory compared to conventional accelerators [2]. In this study, only proton spectrum produced from a selected LDA was compared with the proton flux in different orbits in space despite the fact that there are different types of particle radiation in space. Proton energy spectra for four typical orbits were obtained from the SPENVIS program and the proton energy spectrum produced by a laser driven accelerator system was generated in an EPOCH 2D simulation.
Efficient implementation of finite element methods on non-matching and overlapping meshes in 3D

In recent years, a number of finite element methods have been formulated for the solution of partial differential equations on complex geometries based on non-matching or overlapping meshes. Examples of such methods include the fictitious domain method, the extended finite element method, and Nitsche's method. In all of these methods, integrals must be computed over cut cells or subsimplices which is challenging to implement, especially in three space dimensions. In this note, we address the main challenges of such an implementation and demonstrate good performance of a fully general code for automatic detection of mesh intersections and integration over cut cells and subsimplices. As a canonical example of an overlapping mesh method, we consider Nitsche's method which we apply to Poisson's equation and a linear elastic problem.
Counteracting Adversarial Attacks in Autonomous Driving

This article studies the robust deep stereo vision in autonomous driving systems and counteracting adversarial attacks. The autonomous system operation requires real-time processing of measurement data which often contain significant uncertainties and noise. Adversarial attacks have been widely studied to simulate these perturbations in recent years. To counteract the practical attacks in autonomous systems, novel methods based on simulated attacks are proposed in this article. Univariate and multivariate functions are adopted to represent the relationships between the left and right input images and the deep stereo model. A stereo regularizer is proposed to guide the model to learn the implicit relationship between the images and characterize the loss function’s local smoothness. The attacks are generated by maximizing the regularizer term to break the linearity and smoothness. The model then defends the attacks by minimizing the loss and regularization terms. Two techniques are developed in this article. The first technique, SmoothStereo, explores the basic knowledge from the physical world and smoothness, while the second technique, SmoothStereoV2, improves SmoothStereo through leveraging the smooth activation functions during the defense. SmoothStereoV2 can learn and utilize the gradient information concerning the attacks. The gradients of the smooth activation functions can handle attacks for improving the model robustness. Numerical experiments on KITTI datasets demonstrate that the proposed methods offer superior performance.
Experimental Analysis of Heat Transfer to a Dual Jet Flow: Effect of Reynolds Number

The use of dual jets in industry is widespread, yet the characterisation of dual jet flow remains relatively underrepresented in the published literature. As such, the flow mechanisms and heat transfer capabilities of dual jets is not fully understood, meaning it is not possible to accurately control or optimise their behaviour towards specific applications. This study thus focusses on characterising the heat transfer behaviour of dual jets and analyses the effect of changing the Reynolds number for a constant offset ratio of 3. The Reynolds number of the flow is varied from 5500 to 12000 and Nusselt number data is acquired for a uniform wall flux condition of 2500 W/m2. The results show an increase in the surface Nusselt number with increasing Re, however, the distinct trend with respect to downstream distance from the jet exit remains unchanged.
Reliable force field potential for modelling thermal transport in AlN

A Stillinger-Weber type force field potential (FFP) is parametrized to describe the thermal transport-related properties of AIN. The FFP was fitted to ab-initio data for structural and vibrational properties, such as the lattice and elastic constants as well as the phonon band structure and mode-Grüneisen parameters. For all fitted quantities the resulting FFP yields results in good agreement with the ab-initio data. Moreover, it provides a better description of the bulk thermal conductivity of AIN compared to other FFPs reported in the literature.
Interval-type theorems concerning means

Abstract Each family ℳ of means has a natural, partial order (point-wise order), that is M ≤ N iff M(x) ≤ N(x) for all admissible x. In this setting we can introduce the notion of interval-type set (a subset ℐ ⊂ℳ such that whenever M ≤ P ≤ N for some M, N ∈ℐ and P ∈ℳ then P ∈ℐ). For example, in the case of power means there exists a natural isomorphism between interval-type sets and intervals contained in real numbers. Nevertheless there appear a number of interesting objects for a families which cannot be linearly ordered. In the present paper we consider this property for Gini means and Hardy means. Moreover, some results concerning L∞ metric among (abstract) means will be obtained.
The Undecidability of Conditional Affine Information Inequalities and Conditional Independence Implication With a Binary Constraint

We establish the undecidability of conditional affine information inequalities, the undecidability of the conditional independence implication problem with a constraint that one random variable is binary, and the undecidability of the problem of deciding whether the intersection of the entropic region and a given affine subspace is empty. This is a step towards the conjecture on the undecidability of conditional independence implication. The undecidability is proved via a reduction from the periodic tiling problem (a variant of the domino problem). Hence, one can construct examples of the aforementioned problems that are independent of ZFC (assuming ZFC is consistent).
Uniformly Convex Metric Spaces

Abstract In this paper the theory of uniformly convex metric spaces is developed. These spaces exhibit ageneralized convexity of the metric from a fixed point. Using a (nearly) uniform convexity property a simpleproof of reflexivity is presented and a weak topology of such spaces is analyzed. This topology, called coconvextopology, agrees with the usually weak topology in Banach spaces. An example of a CAT(0)-spacewith weak topology which is not Hausdorff is given.In the end existence and uniqueness of generalized barycenters is shown, an application to isometric groupactions is given and a Banach-Saks property is proved.
Evaluation Of Transformers And Convolutional Neural Networks For High-Dimensional Hyperspectral Soil Texture Classification

Soil texture is an important parameter influencing a multitude of ecosystem services. However, its determination in the laboratory is complex, time-consuming, and only reveals soil texture at a specific sampling point. Therefore, topsoil soil texture determined from space-borne remote sensing data offers advantages (areal and temporal availability, expanding possibilities with upcoming hyperspectral satellite systems). Since no hyperspectral satellite data are available, we use hyperspectral reflectance data provided in the Land Use/Land Cover Area Frame Survey (LUCAS) dataset by the European Soil Data Centre. We resample the provided 4200 bands to the Environmental Mapping and Analysis Program (EnMAP) Resolution of 222 bands. Hereafter, we classify soil texture as sandy, silty, clayey, and loamy from these by applying distinct Transformer architecture as well as a one-dimensional convolutional neural network. Our best models multitemporal SimpleVIT and an ensemble approach score 65.89 % and 67.62 % overall accuracy, respectively.
Continuous and discrete Neumann systems on Stiefel varieties as matrix generalizations of the Jacobi–Mumford systems

We study geometric and algebraic geometric properties of the continuous and discrete Neumann systems on cotangent bundles of Stiefel varieties $V_{n,r}$. The systems are integrable in the non-commutative sense, and by applying a $2r\times 2r$--Lax representation, we show that generic complex invariant manifolds are open subsets of affine (non-compact) Prym varieties on which the complex flow is linear. The characteristics of the varieties and the direction of the flow are calculated explicitly. Next, we construct a family of (multi-valued) integrable discretizations of the Neumann systems and describe them as translations on the Prym varieties, which are written explicitly in terms of divisors of points on the spectral curve. It appears that the systems inherit or naturally generalize the basic properties of the classical Neumann system on $S^{n-1}$ and, therefore, of the Jacobi--Mumford systems: the structure of the Lax matrices, the spectral curve, the equations of motion, linearization on Abelian varieties, and, in the discrete case, the formula for the translation on them.
A Benchmark Biconical Antenna for Standardized Antenna Measurement and Simulation: Contribution to IEEE P2816

The IEEE Antennas and Propagation Standards Committee (APS/SC), sponsored by the IEEE Antennas and Propagation Society (AP-S), is currently developing a recommended practice for the modeling and simulation of antennas, IEEE P2816. It describes standardized procedures using well-known computational electromagnetics techniques for the numerical modeling of antennas in free space. It further includes benchmark problems to help potential users of the recommended practice to better understand the limitations of these computational techniques. A biconical antenna is proposed as a benchmark problem for both numerical simulations and measurements. Several laboratories have participated in the international inter-laboratory comparison of numerical simulation results of the biconical antenna. To confront the theoretical and numerical results with measurements, the same biconical antenna was proposed for fabrication and a complementary inter-laboratory measurement campaign. Herein, the fabrication and initial measurements of the prototype biconical antenna are discussed.
Feature Evaluation for Underwater Acoustic Object Counting and F0 Estimation

When carrying out underwater acoustic target detection mission, we need to count the target number (N), conduct source separation when N is greater than one, and retrieve motion parameters (shaft frequency, or F0 for example) of each target from the separated noises. Though widely adopted in image interpretation, deep learning methods, however, strongly depend on the form or quality of the feed-in data or features, especially for underwater acoustic applications where strong ambient noise and multi-path effects hinders accurate target detection. Therefore, a thorough evaluation of typical features can provide a reference for feature selection in different tasks. In this paper, we choose CRNN, which has been widely validated in time-series analysis, as the common classifier to evaluate different time-frequency features and their enhanced version for object counting and F0 estimation. The performance of feeding STFT, GST, LOFAR, DEMON, or MFCCs as input is analyzed in the two tasks respectively through simulation and lake trial. Experimental results based on lake trial dataset show that both LOFAR and DEMON dominate object counting performance, with an accuracy of 96% and 97%, respectively, while DEMON performs better (94%)in F0 estimation task than LOFAR (83%), partly due to the prominent cavitation in our lake trial dataset. STFT and GST have poor robustness in real environment, while MFCCs fails to cope with both tasks.
Bäcklund Transformations of the Sixth Painlevé Equation in Terms of Riemann-Hilbert Correspondence

It is well known that the sixth Painleve equation PVI admits a group of Backlund transformations which is isomorphic to the affine Weyl group of type D (1) . Although var- ious aspects of this unexpectedly large symmetry have been discussed by many authors, there still remains a basic problem yet to be considered, that is, the problem of charac- terizing the Backlund transformations in terms of Riemann-Hilbert correspondence. In this direction, we show that the Backlund transformations are just the pull-back of very simple transformations on the moduli of monodromy representations by the Riemann- Hilbert correspondence. This result gives a natural and clear picture of the Backlund
Luminance Imaging Measurements for Façades With Asymmetrical Light Reflection

The subject of the research is to reduce light pollution produced by architectural lighting, by decreasing the luminous flux reflected to the sky, but without diminishing the visibility of façades at night. The article is a continuation of the authors' previous article, which showed that a façade with asymmetric reflection can be obtained when using only ordinary materials with diffuse reflection. The method consists of the use of horizontal decorative microprofiles (fins), with dimensions that are easy to achieve technologically. The optimization of the geometry of these profiles is the objective of this article. For optimization, generalized modeling of light reflection in MATLAB is used, through original scripts. These scripts also automatically generate the mesh necessary for the discretization of the façade, for profiles whose angle is modified for the whole range of technologically feasible values. Based on numerical simulations, an optimal domain is identified, based on which the experimental program of effective measurements of the luminance of the façade is optimized, by using imaging.
Combinatorial bases of basic modules for $C_{n}\sp{(1)}$

J.~Lepowsky and R. ~L. ~Wilson initiated the approach to combinatorial Rogers-Ramanujan type identities via vertex operator constructions of standard (i.e. integrable highest weight) representations of affine Kac-Moody Lie algebras. A. ~Meurman and M. ~Primc developed further this approach for $\mathfrak{sl}(2,\mathbb C)\widetilde{}\ $ by using vertex operator algebras and Verma modules. In this paper we use the same method to construct combinatorial bases of basic modules for affine Lie algebras of type $C_{n}\sp{(1)}$ and, as a consequence, we obtain a series of Rogers-Ramanujan type identities. A major new insight is a combinatorial parametrization of leading terms of defining relations for level one standard modules for affine Lie algebra of type $C_{n}\sp{(1)}$.
A procedure for estimating the changes in cosmic ray cutoff rigidities and asymptotic directions at low and middle latitudes during periods of enhanced geomagnetic activity

A procedure is presented for estimating the changes in the cosmic ray cutoff rigidity and the asymptotic directions during geomagnetically active time periods at low- and mid-latitude locations. At a specific location the change in the rigidity associated with the first discontinuity in asymptotic longitude, ΔR1, and the equivalent changes in the other cutoff rigidity parameters can be related to the weighted sum of the changes in the horizontal component of the equatorial surface magnetic field, ΔHeq, sampled at intervals of 1 hour in local time from 0000 to 0700 to the east of the specified location. A set of generalized weighting factors is given for eight cutoff rigidity values in the range from 3 to 13.5 GV. For a cosmic ray particle having a rigidity R the asymptotic direction of approach during perturbed conditions corresponds in good approximation to the asymptotic direction of a particle with rigidity R − ΔR1 propagating through the quiescent geomagnetic field. Asymptotic directions during geomagnetically active periods can therefore be derived from the asymptotic directions computed in a quiescent geomagnetic field model after the associated change in the cutoff rigidity has been deduced from ground-based magnetometer data. The basic principles of the procedure are demonstrated for the cosmic ray station Jungfraujoch, Switzerland.
On generalized K\"ahler geometry on compact Lie groups

We present some fundamental facts about a class of generalized K\"ahler structures defined by invariant complex structures on compact Lie groups. The main computational tool is the BH-to-GK spectral sequences that relate the bi-Hermitian data to generalized geometry data. The relationship between generalized Hodge decomposition and generalized canonical bundles for generalized K\"ahler manifolds is also clarified.
MULTIDIMENSIONAL VAN DER CORPUT SETS AND SMALL FRACTIONAL PARTS OF POLYNOMIALS

We establish Diophantine inequalities for the fractional parts of generalized polynomials $f$, in particular for sequences $\nu(n)=\lfloor n^c\rfloor+n^k$ with $c>1$ a non-integral real number and $k\in\mathbb{N}$, as well as for $\nu(p)$ where $p$ runs through all prime numbers. This is related to classical work of Heilbronn and to recent results of Bergelson \textit{et al.}
Hyperspectral Image Visualization Through Neural Network For The Food Industry

Hyperspectral images (HSI) visualization is important for data annotation, which is used for finding and analyzing foreign objects in food based on machine learning or deep learning techniques. However, HSI visualization is challenging due to the numerous bands compared to RGB images. Recently to address the problem, a lot of methods have been proposed such as color matching function. The color matching function is a representative method based on the human visual system and returns a static value. However, the property sometimes makes results indistinguishable due to the failure to catch the spectrum features. In this paper, we propose a mapping method from HSI to RGB through the neural network that learns the relationships between spectrum and RGB values directly. Our proposed method is evaluated on the dried radish and filefish data obtained from the near-infrared hyperspectral sensor.
Improvement of Radiation Characteristics of a 300-GHz On-Chip Patch Antenna with Epoxy Mold Compound (EMC) Encapsulation

Radiation characteristics of on-chip patch antennas are limited by the metallization and dielectric properties of the back-end of line (BEOL) silicon manufacturing processes. A 300-GHz on-chip patch antenna is designed using a radio frequency (RF) complementary metal-oxide-semiconductor (CMOS) process. The radiation efficiency, peak gain, and impedance bandwidth improve upon encapsulation of the antenna with IC packaging epoxy mold compounds (EMCs). In addition, high-frequency conduction and dielectric losses are analyzed, and their effects on antenna radiation efficiency are quantified in this paper. The overall radiation efficiency is shown to improve by 25%, peak gain by $\sim 3 \ \boldsymbol{\text{dB}}$, and the-10-dB return loss bandwidth improves from 3 GHz to 18 GHz by encapsulating a 300-GHz on-chip patch antenna within commercially available EMCs.
Novel High-Voltage-Gain High-Frequency Nonisolated Three-port DC-DC Converter with Zero Input Current Ripple and Soft Switching Capability

In this paper, a novel structure of three-port with zero voltage switching (ZVS) dc-dc converter is proposed. Three-port dc-dc converters are widely applicable in hybrid energy generating systems to provide substantial power to sensitive loads. One of the ports of the proposed converter is interfaced with a storage such as a battery which makes the converter capable of supplying the load even if the main renewable energy supply of the proposed converter (e.g. photovoltaic cells) is not able to generate power. The proposed converter operates in two operations of charging the battery port and the mode when the battery discharges to the load. In addition, it has ZVS operation for all utilized switches and can eliminate the input current ripple. The ZVS of the switches is provided by the leakage inductances of the used coupled inductors. Also, the voltage control of each of the terminals is achieved by three active switches. In this paper, the proposed topology is analyzed theoretically for all operating modes, also, the voltage and current equations of all components are calculated. Furthermore, the required soft switching and zero input currents ripple conditions are analyzed. Finally, the accuracy performance of the proposed converter and the analytical results is verified by the PSCAD/EMTDC simulation and experimental results for 1MHz switching frequency operation. Applying high frequency and using GaN Fets leads to achieve a more compact prototype of the proposed topology.
Numerical simulations of stellar convective dynamos. II. Field propagation in the convection zone

We present numerical simulations of nonlinear, three-dimensional, time-dependent, giant-cell stellar convection and magnetic field generation. The velocity, magnetic field, and thermodynamic variables satisfy the anelastic magnetohydrodynamic equations for a stratified, rotating, spherical shell of ionized gas. The interaction of rotation and convection produces a nonlinear transport of angular momentum that maintains a differential rotation in radius and latitude. At the surface, our simulated angular velocity peaks in the equatorial region in agreement with Doppler measurements of the solar surface rotation rate; below the surface, it decreases with depth in agreement with what is inferred from the rotational frequency splitting of solar oscillations. The interaction of rotation and convection also maintains left-handed helical fluid motions in the northern hemisphere and right-handed motions in the southern hemisphere. Magnetic fields are generated by the shearing and twisting effects of the differential rotation and helical motions and are destroyed by eddy diffusion. They in turn feedback onto the velocity and thermodynamic fields via the Lorentz force and Joule heating. Although we have not continued the computation long enough to simulate a complete magnetic cycle, our solutions demonstrate how the induced magnetic fields propagate away from the equator in the opposite direction inferred from themore » solar butterfly diagram. We suggest that, instead of operating in the turbulent convective region, the solar dynamo may be operating at the base of the convection zone where our simulated helicity has the opposite sign and a smaller amplitude. « less