Miracle-dz/UniFAR-FTUs huggingface dataset:
On the regularity of solutions of a homogeneous Dirichlet problem for a non-hypoelliptic linear partial differential operator

1.1. In the study of the regularity of generalized solutions of various problems for partial differential equations the notion of the hypoellipticity of linear partial differential operators has a central role. Originally the hypoelliptic operators were introduced by L. Hormander in 1955, and for the results of the development one can today consult his monograph [13], especially chapters LL and 1.3. A linear differential operator P(.,D) defined in some open set O in R" through
Experimental evidence of end effects in magneto-electric laminate composites

This paper experimentally and theoretically studies the magneto-electric (M-E) responses of layered magnetostrictive and piezoelectric composites. A total of three different piezoelectric volume fractions of 0.17, 0.29, and 0.44 were prepared to investigate the strain variation in the sample and the effective M-E voltage coefficient α¯ as a function of bias magnetic field Hbias. Analytical modeling involving uniform strain, shear lag only, and shear lag plus demagnetization was performed and compared with experimental measurements. The results demonstrate that the uniform strain theory significantly overestimates the measured strain and α¯ values. This discrepancy is physically attributed to shear lag and demagnetizing effects. The analytical models involving shear lag and demagnetizing effects agree with the experimental results well within 5%.
String Theory For Dummies

Introduction. Part I: Introducing String Theory. Chapter 1: So What Is String Theory Anyway? Chapter 2: The Physics Road Dead Ends at Quantum Gravity. Chapter 3: Accomplishments and Failures of String Theory. Part II: The Physics Upon Which String Theory Is Built. Chapter 4: Putting String Theory in Context: Understanding the Method of Science. Chapter 5: What You Must Know about Classical Physics. Chapter 6: Revolutionizing Space and Time: Einstein's Relativity. Chapter 7: Brushing Up on Quantum Theory Basics. Chapter 8: The Standard Model of Particle Physics. Chapter 9: Physics in Space: Considering Cosmology and Astrophysics. Part III: Building String Theory: A Theory of Everything. Chapter 10: Early Strings and Superstrings: Unearthing the Theory's Beginnings. Chapter 11: M-Theory and Beyond: Bringing String Theory Together. Chapter 12: Putting String Theory to the Test. Part IV: The Unseen Cosmos: String Theory On the Boundaries of Knowledge. Chapter 13: Making Space for Extra Dimensions. Chapter 14: Our Universe - String Theory, Cosmology, and Astrophysics. Chapter 15: Parallel Universes: Maybe You Can Be Two Places at Once. Chapter 16: Have Time, Will Travel. Part V: What the Other Guys Say: Criticisms and Alternatives. Chapter 17: Taking a Closer Look at the String Theory Controversy. Chapter 18: Loop Quantum Gravity: String Theory's Biggest Competitor. Chapter 19: Considering Other Ways to Explain the Universe. Part VI: The Part of Tens. Chapter 20: Ten Questions a Theory of Everything Should (Ideally) Answer. Chapter 21: Ten Notable String Theorists. Index.
Optical-clock local-oscillator stabilization scheme

Stabilization of a laser to an optical-clock transition has been demonstrated using Ramsey's phase-modulation technique. The technique was implemented using a 674 nm laser and a component of the 5 s 2S1/2 → 4d 2D5/2 optical clock transition in a single 88Sr+ ion. The lock performance observed was consistent with the short-term stability of the local oscillator. Compared with existing frequency-modulation stabilization schemes, this technique offers advantages for use in single-ion optical clocks through its possible increased resolution and the ability to conveniently compensate known systematic shifts.
Co/Pt superlattices with ultra-thin Ta seed layer on NiFe underlayer for double-layer perpendicular magnetic recording media

Co/Pt superlattices with an ultra-thin amorphous Ta seed layer on a Ni/sub 45/Fe/sub 55/ underlayer were fabricated for double-layer perpendicular magnetic recording media using a special hard disk sputtering system with a triple-target DC magnetron cathode (Triatron). A 2.5 nm thick Ta seed layer was found to improve the crystalline structure and increase the coercivity of the Co/Pt superlattices from 1.13 to 2.17 kOe. A 2.5 nm Ta layer on a 200 nm thick magnetically soft NiFe underlayer was found to further increase the coercivity from 2.25 to 5 kOe. In addition, the sheared slope of the sides of hysteresis loop of Co/Pt superlattices was significantly improved from about 5 Gauss/Oe (with only a 2.5 nm Ta seed layer) to about 1.1 Gauss/Oe (with both a 2.5 nm Ta seed layer and a 200 nm NiFe underlayer).
Hyperspectral image lossless compression algorithm based on error compensated prediction tree of multi-band prediction

A new lossless compression method based on prediction tree with error compensation for hyperspectral imagery is proposed in this paper. This method incorporates the techniques of prediction tree and adaptive band prediction. The proposed method is different from previous similar approaches in that its prediction to the current band is performed by multiple bands and the error created by the prediction tree is compensated by a linear adaptive predictor for decorrelating spectral statistical redundancy. After de-correlating intraband and interband redundancy, the SPIHT (Set Partitioning in Hierarchical Trees) wavelet coding is used to encode the residual image. The proposed method achieves high compression ratio on the NASA JPL AVIRIS data.
Localization and Dualities in Three-dimensional Superconformal Field Theories

In this thesis we apply the technique of localization to three-dimensional N=2 superconformal field theories. We consider both theories which are exactly superconformal, and those which are believed to flow to nontrivial superconformal fixed points, for which we consider implicitly these fixed points. We find that in such theories, the partition function and certain supersymmetric observables, such as Wilson loops, can be computed exactly by a matrix model. This matrix model consists of an integral over g, the Lie algebra of the gauge group of the theory, of a certain product of 1-loop factors and classical contributions. One can also consider a space of supersymmetric deformations of the partition function corresponding to the set of abelian global symmetries. In the second part of the thesis we apply these results to test dualities. We start with the case of ABJM theory, which is dual to M-theory on an asymptotically AdS_4xS^7 background. We extract strong coupling results in the field theory, which can be compared to semiclassical, weak coupling results in the gravity theory, and a nontrivial agreement is found. We also consider several classes of dualities between two three-dimensional field theories, namely, 3D mirror symmetry, Aharony duality, and Giveon-Kutasov duality. Here the dualities are typically between the IR limits of two Yang-Mills theories, which are strongly coupled in three dimensions since Yang-Mills theory is asymptotically free here. Thus the comparison is again very nontrivial, and relies on the exactness of the localization computation. We also compare the deformed partition functions, which tests the mapping of global symmetries of the dual theories. Finally, we discuss some recent progress in the understanding of general three-dimensional theories in the form of the F-theorem, a conjectured analogy to the a-theorem in four dimensions and c-theorem in two dimensions, which is closely related to the localization computation.
Numerical Investigations of Free Surface Flow in a Channel with a Long Contraction

In the present study a three dimensional numerical model is used to predict the flow in a channel with a long contraction and a ne gravel bed. The numerical results are compared with experimental data. In the beginning of the contraction the water accelerates. A distinct drop in the water level can be observed. In the expansion area a recirculation zone forms. Here the water elevation increases again, but to a lower level than before the contraction. For the cases with a higher discharge, a local hydraulic jump occurs in the beginning of the contraction. The numerical results show good agreement with the experimental data. The numerical model uses the level set method in addition with Lagrangian particle correction for the calculation of the free water level. With this front-capturing method the free surface is modeled as the zero level set of a scalar signed distance function. In order to maintain this property and to ensure mass conservation, the level set function is reinitialized after each time step. Surface tension is taken into account with the continuum surface force method. The convective terms including the level set function and the equations of the k-ω turbulence model are discretized with the fifth-order finite difference WENO scheme. It ensures a smooth and oscillation free solution for large gradients and even shocks while maintaining a high order discretization at the same time. The pressure is discretized with the projection method. The Poisson equation for the pressure is solved with the preconditioned BiCGStab algorithm. The staggered grid configuration leads to a tight velocity-pressure coupling. For time discretization a second-order Adams-Bashforth scheme is used. Parallelization of the numerical scheme is achieved by using the domain decomposition framework together with the MPI library. Since the numerical model employs a Cartesian grid, the present study requires special attention to the geometry of the contraction and the expansion. Here an immersed boundary method based on ghost cell extrapolation is used.
Loss of Chaos in Combustion Noise as a Precursor of Impending Combustion Instability

Combustion noise has been traditionally thought of as stochastic fluctuations present in the background of the dynamics in combustors amongst the flow, heat release and the chamber acoustics. Through a series of determinism tests, we show that these aperiodic fluctuations are in fact chaotic of moderately high dimensions (d0 ≅ 8–10). These chaotic fluctuations then transition to high amplitude combustion instability when the operating conditions are varied towards leaner equivalence ratios. Precursors to such a transition from chaos to dynamics dominated by periodic oscillations are of interest to designers and operators of combustors in estimating the boundaries of operability. We introduce a test for chaos, known as 0–1 test for chaos in the literature, as a measure of the proximity of the combustor to an impending instability. The measure is robust and shows a smooth transition for variation in flow conditions towards instability enabling thresholds to be set for operational boundaries.
The Solar Corona Above Polar Coronal Holes as Seen by SUMER on SOHO

In order to address two of the principal scientific objectives of the Solar and Heliospheric Observatory (SOHO), studies of the heating mechanisms of the solar corona and the acceleration processes of the solar wind, we deduce electron temperatures, densities, and ion velocities in plumes and interplume regions of polar coronal holes using ultraviolet observations from SUMER (Solar Ultraviolet Measurements of Emitted Radiation) on SOHO. SUMER allows us to study the inner corona up to a distance of about 430,000 km above the limb, or r = 1.6 R☉ (solar radius) from the center of the disk. We find the electron temperatures, Te, to be less than 800,000 K in a plume in the range from r = 1.03 to 1.60 R☉, decreasing with height to ≈ 330,000 K. Near an interplume lane, the electron temperature is also low, but stays between 750,000 and 880,000 K in the same height interval. Doppler widths of O VI lines in plumes are narrower (ΔλD ≈ 150 mÅ, v1/E ≈ 43 km s-1) than in interplume lanes (≈ 190 mÅ, ≈ 55 km s-1). The thermal and turbulent ion speeds, v1/E, of Si7+ reach values up to ≈ 80 km s-1 in the darkest regions outside plumes above the coronal hole. This corresponds to a kinetic ion temperature of 1 × 107 K. A limit of ≈ 18 km s-1 for the bulk speed in plumes below r = 1.2 R☉ is deduced from O VI line shift measurements and consideration of the three-dimensional plume geometry (differential line-of-sight velocities ≤3 km s-1), whereas differential line-of-sight velocities of Mg8+ ions up to 34 km s-1 can be seen in dark regions.
Residual-gradient-based neural reinforcement learning for the optimal control of an acrobot

Based on the idea of dynamic programming, reinforcement learning (RL) has become an important model-free method to solve difficult optimal control problems. In this paper, a novel neural RL method is proposed to solve the time-optimal control problem of a class of under-actuated robots, which is called the acrobot. The RL method uses a modified residual gradient reinforcement learning algorithm called RGNP (residual gradient with nonstationary policy). The RGNP algorithm not only has guaranteed convergence under certain conditions but also can ensure the performance of the approximated optimal policy, which is superior to the previous residual gradient algorithms. Simulation results of the learning control of the acrobot illustrate the effectiveness of the proposed method.
Microscopic mechanisms for photoinduced metastability in amorphous As2S3

Using clusters of atoms that model the local structure of amorphous As2S3 (a-As2S3), we here present a model of photoinduced structural changes in a-As2S3 . We have performed quantum-chemical calculations on the model clusters and have obtained their equilibrium configurations, charge distributions, molecular-orbital structures, and excitation energies. It has been found that there exist at least two types of metastable structural defects. One has a fivefold-coordinated As unit, and the other comprises a fourfold-coordinated As atom and a nonbridging S atom. Each type of defect results from the breaking of an As-S bond and subsequent structural rearrangement. From the calculations of the excitation energies, we suggest that the fivefold As defect is responsible for a parallel redshift of the optical absorption edge upon light exposure, called photodarkening. On the other hand, the fourfold As defect is likely to contribute to the photoinduced midgap absorption below ;2 eV induced by low-temperature light exposure. It has also been demonstrated that the formation of these metastable defects is closely associated with interlayer atomic reconfigurations resulting in homopolar As-As linkages.
Current-induced magnetization switching in exchange-biased spin valves for current-perpendicular-to-plane giant magnetoresistance heads

In contrast to earlier studies performed on simple $\mathrm{Co}∕\mathrm{Cu}∕\mathrm{Co}$ sandwiches, we have investigated spin-transfer effects in complex spin-valve pillars with a diameter of 130 nm developed for current-perpendicular-to-plane magnetoresistive heads. The structure of the samples included an exchange-biased synthetic pinned layer and a free layer, both laminated by insertion of several ultrathin Cu layers. Despite the small thickness of the polarizing layer, our results show that the free layer can be switched between the parallel (P) and the antiparallel (AP) states by applying current densities of the order of ${10}^{7}\phantom{\rule{0.3em}{0ex}}\mathrm{A}∕{\mathrm{cm}}^{2}$. A strong asymmetry is observed between the two critical currents ${I\phantom{\rule{0.1em}{0ex}}}_{c}^{\mathrm{AP}\text{\ensuremath{-}}\mathrm{P}}$ and ${I}_{c}^{\mathrm{P}\text{\ensuremath{-}}\mathrm{AP}}$, as predicted by the model of Slonczewski. Due to the use of exchange-biased structures, the stability phase diagrams could be obtained in the four quadrants of the $(H,I)$ plan. The critical lines derived from the magnetoresistance curves measured with different sense currents, and from the resistance versus current curves measured for different applied fields, match each other very well. The main features of the phase diagrams can be reproduced by investigating the stability of the solutions of the Landau-Lifshitz-Gilbert equation including a spin-torque term, within a macrospin model.
Progress Toward a Search for a Permanent Electric Dipole Moment in Liquid$^{129}$XE

Here we report progress toward the measurement of a permanent electric dipole moment (EDM) in hyperpolarized liquid 129 Xe which violates invariance under both parity and time reversal. The standard model (SM) predicts atomic EDMs well beyond current experi- mental limits while many natural extensions to the SM predict EDMs within the expected sensitivity of current experiments. Hence the search for a non-zero EDM is viewed as an ideal test for new physics. Liquid 129 Xe is an attractive medium in which to perform such a search because it has a high number density and a high electric field breakdown strength. For experimentally realizable parameters it should be possible to achieve a sensitivity of a 10 ° 32 e -cm for one day of integration, several orders of magnitude beyond current experimental limits on EDMs. In preparation for performing a search for an EDM in liquid xenon, we have conducted a thorough experimental and theoretical investigation of the spin dynamics of hyperpolarized liquid 129 Xe. In a highly polarized liquid magnetic dipolar interactions can strongly influence spin precession. For small tip angles of the magnetization away from the holding field, the system is insensitive to perturbations, leading to extended free induction decays. For large tip angles the system develops a dynamical instability so that spin precession due to a small magnetic field gradient is amplified exponentially relative to the non-interacting case. In principle, this amplification can be quite large, leading to enhanced sensitivity of spin precession measurements when noise in the detection system is much greater than spin- projection noise. Experimentally, we have achieved amplification of spin precession due to a small applied field gradient by a factor of 9.5 relative to the non-interacting case in the large tip angle regime. Considerable improvement is expected with further optimization of high order gradients. In the small tip angle regime we have realized an extension of the free induction decay by up to a factor of 100 compared to the non-interacting case. We discuss how these two different regimes can be used in a search for an EDM in liquid xenon and analyze the expected sources of systematic effects.
Piezoelectrically driven XYθ table for submicron lithography systems

A newly designed piezoelectrically driven XYθ table has been developed for submicron lithography systems. The XYθ table was fabricated using a monolithic plate structure, joined together with flexure hinges and driven by an inchworm function. This function involves the periodic clamping and unclamping of four blocks and the expansion and contraction of piezoelectric actuators. The XYθ table can travel a long distance with fine positioning in the X, Y, and θ directions. The velocities can be controlled up to 0.5 mm/s in the X and Y directions, and 0.3×10 −2 rad/s in the θ direction by changing the inchworm function stepping rate. Positioning accuracy of less than 1 μm in the X and Y directions, and 7.5×10−6 rad in the θ direction can easily be obtained using a servo system with a 0.5‐μm measuring resolution.
In vivo multi-photon nanosurgery on cortical neurons: focusing on network organization

Two-photon microscopy has been used to perform high spatial resolution imaging of spine plasticity in the intact neocortex of living mice. Multi-photon absorption has also been used as a tool for the selective disruption of cellular structures in living cells and simple organisms. In this work we exploit the spatial localization of multi-photon excitation to perform selective lesions on the neuronal processes of cortical neurons in living mice expressing fluorescent proteins. This methodology was applied to dissect single dendrites with sub-micrometric precision without causing any visible collateral damage to the surrounding neuronal structures. The spatial precision of this method was demonstrated by ablating individual dendritic spines, while sparing the adjacent spines and the structural integrity of the dendrite. The morphological consequences were then characterized with time lapse 3D two-photon imaging over a period of minutes to days after the procedure. Here we present the results of our systematic study of the morphological response of cortical pyramidal neurons to nanosurgical perturbations. Dendritic branches were followed after transecting distal segments, whilst the plasticity and remodeling of individual dendritic spines on a given branch was also followed after removing of a subset of spines.
Inverse scattering: an iterative numerical method for electromagnetic imaging

The authors propose a spatial iterative algorithm for electromagnetic imaging based on a Newton-Kantorovich procedure for the reconstruction of the complex permittivity of inhomogeneous lossy dielectric objects with arbitrary shape. Starting from integral representation of the electric field and using the moment method, this technique has been developed for 2-D (for TM and TE polarization cases) objects as well as for 3-D objects. Its performance has been compared with spectral techniques of classical diffraction tomography, the modified Newton method, and the pseudo-inverse method. >
East India Coastal Current induced eddies and their interaction with tropical storms over Bay of Bengal

Eddies of about 10 to 500km in diameter, persisting for periods of days to months are commonly referred to as mesoscale eddies in oceanography. Energetic eddies are frequently found in the vicinity of faster flowing currents like the Gulf Stream and the Kuroshio. The present study deals with the role of eddies, occurring in the vicinity of the East India Coastal Current (EICC), particularly in the months of April to May and October to November, during the intensification of tropical cyclones in the Bay of Bengal. Although the Bay of Bengal is well known for mesoscale eddies, the role of these in the intensification/weakening of the storms is quantitatively unknown. In this study, an attempt has been made to conduct a quantitative analysis of the role of these eddies (warm/cold) in the intensification of the storms over the Bay of Bengal. It is found that in the case of a severe cyclone occurring over the period of 16 to 19 October, 1999 the intensity of the storm was enhanced by 260% due to its interaction with a warm eddy. This is much higher than that reported in case of, for example, Hurricane Opal (119%) and Typhoon Maemi (138%). The enthalpy fluxes (latent plus sensible) are much higher (lower) over warm (cold) eddies. The warm eddy opposes the cooling induced by the storm and helps the intensification through the supply of large amount of enthalpy flux. This emphasizes the importance of eddies in the intensification of storms over the Bay of Bengal, which is omitted by meteorologists in forecasting the intensification of storms.
INFERENCE FOR STRESS-STRENGTH MODELS BASED ON WEINMAN MULTIVARIATE EXPONENTIAL SAMPLES

The analysis of stress-strength systems is connected to the probability P(X < Y), where X represents the stress subject to an object and Y is its strength. We consider estimation of P(X < Y) when the underlying data consists of two samples of order statistics from Weinman multivariate exponential distributions with a common location parameter. Maximum likelihood estimators and uniform minimum variance unbiased estimators of P(X < Y) are presented, when the location parameter is assumed to be known and unknown, respectively. Moreover, some distributional properties, a confidence interval and asymptotic results are established. The results can be applied to various data set-ups based on exponential distributions, e.g., ordinary order statistics, progressive type II censored order statistics, sequential order statistics and record values.