Miracle-dz/UniFAR-FTUs huggingface dataset:
Nonlinear Path Following Method

This paper develops a new guidance logic for a vehicle to converge to a specified, desired path of general shape in three dimensions. Conditions are found that ensure exponential convergence to the path for any initial vehicle position and velocity vector, excluding only the velocity vector normal to the desired path. The guidance logic includes a ghost vehicle that follows the desired path. The command accelerations are derived from fictitious forces that act in a frame of reference that moves with the ghost. The forces comprise a springlike force between vehicle and ghost and a drag force created by a fictitious medium that moves with the ghost. The motion of the ghost is determined indirectly by a nonlinear constraint that controls the real vehicle speed and leads to a differential-algebraic system of equations. The path equations are formulated in terms of differential geometry, in which time is replaced by distance along the vehicle path. The geometric equations are transformed into standard form differential equations. These are transformed again into kinetic equations for both a fixed medium and a moving medium. The transformed equations provide more explicit formulas for command accelerations and are used to ensure that commands do not exceed the capabilities of the vehicle. Often, the vehicle limitation is more constraining than the convergence conditions. Simulations of a miniature aircraft, using these equations, illustrate the effectiveness of the method. Other methods are compared.
The Vertical Vorticity Structure within a Squall Line Observed during BAMEX: Banded Vorticity Features and the Evolution of a Bowing Segment

AbstractA quasi-linear convective line with a trailing stratiform region developed during the Bow Echo and Mesoscale Convective Vortex Experiment (BAMEX) while being sampled by two airborne Doppler radars. The finescale reflectivity and Doppler velocities recorded by the radars documented the evolution of the convective line. Bands of positive and negative vertical vorticity oriented parallel to the convective line were resolved in the analysis. This type of structure has rarely been reported in the literature and appears to be a result of the tilting and subsequent stretching of ambient horizontal vorticity produced by the low-level wind shear vector with a significant along-line component. The radar analysis also documented the evolution of an embedded bow echo within the convective line. Embedded bow echoes have been documented for a number of years; however, a detailed analysis of their kinematic structure has not been previously reported in the literature. The counterrotating circulation patterns tha.
Soap bubbles in paintings: Art and science

Soap bubbles became popular in 17th century paintings and prints primarily as a metaphor for the impermanence and fragility of life. The Dancing Couple (1663) by the Dutch painter Jan Steen is a good example which, among many other symbols, shows a young boy blowing soap bubbles. In the 18th century the French painter Jean-Simeon Chardin used soap bubbles not only as metaphor but also to express a sense of play and wonder. In his most famous painting, Soap Bubbles (1733/1734) a translucent and quavering soap bubble takes center stage. Chardin’s contemporary Charles Van Loo painted his Soap Bubbles (1764) after seeing Chardin’s work. In both paintings the soap bubbles have a hint of color and show two bright reflection spots. We discuss the physics involved and explain how keenly the painters have observed the interaction of light and soap bubbles. We show that the two reflection spots on the soap bubbles are images of the light source, one real and one virtual, formed by the curved surface of the bubble.
Bargaining under Uncertainty and the Monotone Path Solutions

Abstract Uncertainty with respect to the feasible set of utility vectors is introduced in an axiomatic bargaining model. Given a criterion for nonprobabilistic decision-making under uncertainty, a natural efficiency requirement can be imposed on a bargaining solution. Using the maximin ordering, the strictly monotone path solutions (generalizations of the egalitarian solution) to the bargaining problem are characterized as the only continuous solutions that satisfy this efficiency axiom. If the maximin criterion is replaced by the maximax ranking or a strict convex combination of the maximin and the maximax criterion, imposing our efficiency axiom and continuity leads to the dictatorial solutions. Journal of Economic Literature Classification Number: C78.
Dynamic properties of flexural beams using a nonlocal elasticity model

In this paper, a nonlocal Bernoulli-Euler beam model is established based on the theory of nonlocal elasticity. Frequency equations and modal shape functions of beam structures with some typical boundary conditions are derived based on the model. The corresponding dynamic properties are presented and discussed in detail, which are shown to be very different from those predicted by classic elasticity theory when nonlocal effects are significant. The results can be applied to modeling and characterization of size-dependent mechanical properties of micro- or nanoelectromechanical system (MEMS or NEMS) devices.
Modelling indentation creep of polymers: a phenomenological approach

The room temperature nanoindentation creep behaviour of a range of amorphous and semicrystalline polymers has been investigated. It was found that experimental data during the first 20 s at constant load were well fitted by a logarithmic equation relating the fractional increase in penetration depth during creep to [A/d(0)]ln(t/τ + 1) where A and τ are constants, d(0) is the initial penetration depth at the end of the loading period and t is the time at peak load. For samples of ultra-high molecular weight polyethylene and polypropylene, above their glass transition temperature at room temperature, it was found that the creep parameter A/d(0) increased at lower load and at higher loading rates when a Berkovich indenter was used. In contrast, samples of poly(methylmethacrylate) and poly(ethylene terephthalate), below their glass transition at the test temperature, showed no clear variation in A/d(0) with loading rate. The constant τ varied with loading rate (and hence loading time), following a power-law relationship. Fitting of creep data with the equation above enables prediction of the extent and rate of the creep occurring after any given combination of loading rate and maximum load with reasonable accuracy, particularly at higher load. Importance should be placed on the actual loading rate and time to reach peak load as this is shown to influence the initial creep kinetics dramatically.
Stabilization of autonomous linear time invariant fractional order derivative switched systems with different derivative in subsystems

Abstract. In this paper, the stabilization problem of a autonomous linear time invariant fractional order (LTI-FO) switched system with different derivative order in subsystems is outlined. First, necessary and sufficient condition for stability of an LTI-FO switched system with different derivative order in subsystems based on the convex analysis and linear matrix inequality (LMI) for two subsystems is presented and proved. Also, sufficient condition for stability of an LTI-FO switched system with different derivative order in subsystems for more than two subsystems is proved. Then a sliding sector is designed for each subsystem of the LTI-FO switched system. Finally, a switching control law is designed to switch the LTI-FO switched system among subsystems to ensure the decrease of the norm of the switched system. Simulation results are given to show the effectiveness of the proposed variable structure controller.
Annealing Markov chain Monte Carlo with applications to ancestral inference

Abstract Markov chain Monte Carlo (MCMC; the Metropolis-Hastings algorithm) has been used for many statistical problems, including Bayesian inference, likelihood inference, and tests of significance. Though the method generally works well, doubts about convergence often remain. Here we propose MCMC methods distantly related to simulated annealing. Our samplers mix rapidly enough to be usable for problems in which other methods would require eons of computing time. They simulate realizations from a sequence of distributions, allowing the distribution being simulated to vary randomly over time. If the sequence of distributions is well chosen, then the sampler will mix well and produce accurate answers for all the distributions. Even when there is only one distribution of interest, these annealing-like samplers may be the only known way to get a rapidly mixing sampler. These methods are essential for attacking very hard problems, which arise in areas such as statistical genetics. We illustrate the methods wi.
Room-temperature saturated ferroelectric polarization in BiFeO3 ceramics synthesized by rapid liquid phase sintering

Single-phased ferroelectromagnet BiFeO3 ceramics with high resistivity were synthesized by a rapid liquid phase sintering technique. Saturated ferroelectric hysteresis loops were observed at room temperature in the ceramics sintered at 880 °C for 450 s. The spontaneous polarization, remnant polarization, and the coercive field are 8.9 μC/cm2, 4.0 μC/cm2, and 39 kV/cm, respectively, under an applied field of 100 kV/cm. It is proposed that the formation of Fe2+ and an oxygen deficiency leading to the higher leakage can be greatly suppressed by the very high heating rate, short sintering period, and liquid phase sintering technique. The latter was also found effective in increasing the density of the ceramics. The sintering technique developed in this work is expected to be useful in synthesizing other ceramics from multivalent or volatile starting materials.
Earth's core convection: Boussinesq approximation or incompressible approach?

Most geodynamo models are based on the Boussinesq approximation that simplifies the mathematics of the problem by neglecting the compressibility of the liquid in the Earth's core. However, the Boussinesq approximation not only disregards the compressibility in the momentum and the continuity equations, but also neglects adiabatic cooling in the heat transport equation which is connected with the reference state temperature distribution . Whereas the former simplification introduces an acceptable inaccuracy, the latter changes the scene in a substantial way and makes the Boussinesq approximation nonadequate for the problem, especially at the onset of the convection. We prove that adiabatic cooling does not vanish in the incompressible limit used by the Boussinesq approximation and propose a new incompressible approach (IA), which neglects the direct influence of compressibility, but takes into consideration its indirect cooling effects. There is not only adiabatic cooling, but also Archimedean cooling (heating) connected with Archimedean work. This last effect allows Ohmic dissipation to be included consistently in the heat transport equation. Using the adiabatic cooling as a natural inhomogeneity in the heat equation allows the typical amplitudes of the superadiabatic temperature, flow velocity, and magnetic field in the solution to be estimated. These amplitudes are in good agreement with those given by the simulation of Glatzmaier and Roberts (An anelastic evolutionary geodynamo simulation driven by compositional and thermal convection. Physica D, 1996, 97, 81–94). Finally these amplitudes are used to obtain dimensionless equations of the IA. The coefficient with the Archimedean force, usually called the Rayleigh number, takes a moderate value of the order of R m instead of the enormous quantities which the Boussinesq approximation usually attributes to it.
The Seasonal Cycle of Longitude-dependent Ozone Transport by Large-scale Waves in the Northern Hemisphere

The dependence of longitude-dependent total ozone patterns on large-scale wave structures is analyzed by a pattern correlation of the mean fields (climatology), as well as of the decadal change (trend) for the 1979 to 1992 period. In all months, there exists a significant negative regression between total ozone and 300 hPa geopotential height patterns for the climatology (annual average: -0.18 DU/m), and for the trend (-0.14(DU/10 years)/(m/10 years)). For both, the regression coefficients exhibit an asymmetric annual variation with respect to the solstices with significantly higher values in spring, and lower values in autumn. Assuming that the ozone transport is primarily caused by the annual variation of large-scale wave transport in a background ozone field, we show that the seasonal cycles are mainly determined by the asymmetric annual variation of the gradients of the zonal mean ozone field, and not by the annual variability of the wave activity.
GT efficacy: a performance measure for cell formation with sequence data

Cell formation in cell manufacturing design is a crucial step for improving productivity. As input data for the cell formation problem, a part-machine incidence matrix is given in binary format or in ordinal format. The solutions for effective cell formation have to be compared using performance measures. Grouping efficacy is used as a standard measure for evaluating solutions based on a binary part-machine matrix, which does not consider ordinal data. However, the representative measures, called standard measures, for the ordinal part-machine matrix are absent. The existing measures designed for ordinal data produce conflicting results and can lead to subjective decisions. In this paper, a new objective measure called group technology (GT) efficacy is proposed for ordinal data, reflecting on both intercellular movement and compactness within cells simultaneously. The advantage of GT efficacy is demonstrated by comparing it with a few previously-proposed measures.
Study of InGaN Multiple Quantum Dots by Metal Organic Chemical Vapor Deposition

We reports a study of InGaN multiple quantum dot layers. Using the in-situ SiNx treatment process, InGaN multiple quantum dot layers were successfully developed. The InGaN multiple quantum dot layers were constructed with SiNx dot mask layers, InGaN dot layers, and GaN cap layers on a 2-µm-thick GaN underlying layer on a sapphire substrate. Optical properties including room temperature photoluminescence (PL), temperature dependent PL, and low power power-dependent PL were examined and discussed. The structure was also analyzed by transmission electron microscopy (TEM) and energy dispersive X-ray (EDX) line scan.
Probabilistic Seasonal Prediction of Meteorological Drought Using the Bootstrap and Multivariate Information

AbstractIn the present work, a probabilistic ensemble method using the bootstrap is developed to predict the future state of the standard precipitation index (SPI) commonly used for drought monitoring. The methodology is data driven and has the advantage of being easily extended to use more than one variable as predictors. Using 110 years of monthly observations of precipitaton, surface air temperature, and the Nino-3.4 index, the method was employed to assess the impact of the different variables in enhancing the prediction skill. A predictive probability density function (PDF) is produced for future 6-month SPI, and a log-likelihood skill score is used to cross compare various combination scenarios using the entire predictive PDF and with reference to the observed values set aside for validation. The results suggest that the multivariate prediction using complementary information from 3- and 6-month SPI and initial surface air temperature significantly improves seasonal prediction skills for capturing d.
Noise sources in the LTP heterodyne interferometer

The LISA Technology Package uses a heterodyne Mach–Zehnder interferometer to monitor the relative motion of the test masses with picometer accuracy. This paper discusses two classes of noise sources that were identified and investigated during the prototype experiments. Most troublesome are electrically induced sidebands on the light, which give rise to nonlinearities in the interferometer output. Even worse, if the differential pathlength between two optical fibres fluctuates, a noise term of milliradian amplitude appears and completely spoils the performance. We discuss the origin and mitigation of this process. Dissimilar beam shapes of the interfering beams produce another type of noise in conjunction with beam jitter and spatially inhomogeneous photodetectors. To study and minimize this effect, we have built a real-time high-resolution phasefront imaging system that will be used for the production of the flight model.
Ab initio study of self-diffusion in silicon over a wide temperature range: Point defect states and migration mechanisms

We identified the states of intrinsic point defects underlying the self-diffusion in Si and clarified the change of dominant diffusion mechanism responsible for the self-diffusion over a wide temperature range using ab initio method. We presented a reliable self-diffusion model that the mechanisms of vacancies and self-interstitials dominate below and above 1220 K, respectively. Our calculations provided a clear picture of Si self-diffusion at lower and higher temperature ascribed to single point defects rather than extended defects. The calculations also provided valuable information on the energy levels and the thermal equilibrium concentrations of point defects, which are highly controversial in experimental reports due to detection limits.
Statistical-Dynamical Predictions

Abstract By analogy with Gibbs' statistical mechanics, a statistical-dynamical theory is described which can be applied to the problem of atmospheric predictions from synoptic charts. The m variables and constants whose measurement is needed to characterize an initial state are regarded as coordinates of an m dimensional phase space. In this space, the probability density ψ of the ensemble of possible initial measurements is used to define the “true” values of these quantities and to furnish probabilities of initial measurements lying within prescribed limits of true values. Dynamical equations provide standard deterministic predictions here, while a general continuity equation for ψ transforms initial probability distributions into final ones which, in turn, yield probability forecasts. This continuity equation is resolvable into component equations of probability diffusion for all coordinates of the phase space. It is found that predictability increases (decreases) with time if the atmosphere is diverge.
The Superfluid Phases Of Helium 3

A comprehensive treatment of the theory of superfluid helium-3 is presented in this book. This treatment also illustrates many of the principal themes of theoretical condensed matter physics over the past two decades. The generalized BCS (Barden-Cooper-Schrieffer) pairing theory and the experimental properties of superfluid helium-3 are treated in detail. Extensive treatment of broken symmetries and their relation to macroscopic order and of the closely related topics of superflow and texture, defects in the order parameter field, and the dynamics of the nuclear spins as probed by nuclear magnetic resonance is included. This book should serve as a valuable reference for anyone working on superfluid helium-3 or on the closely related topics of unconventional superconductivity in heavy-electron metals and superfluidity of neutron star interiors.
A Simple Method for Solving Dynamic Problems of Robotics

In this paper we find a general solution for the action function in the case of a heavy point moving on a sphere using the method of separation of the Hamilton-Jacobi equation variables. The solution contains two constants: the energy of a material point and the momentum projection onto a horizontal direction. We analyze the modes of a spherical pendulum oscillation. It is shown that the solution does not contain any errors of accumulation which are characteristic for evolution problems with long prediction periods.
Sandfish inspires engineering

The sandfish (Scincidae: Scincus scincus) is a lizard having the remarkable ability to move through desert sand in a swimming-like fashion. The most outstanding adaptation to its subterranean life is the epidermis that shows low friction behaviour and extensive abrasion resistance against sand, outperforming even steel. The skin consists of glycosylated keratins, which were found to be absolutely necessary for the described phenomenon. Here we discuss the function of serrated microstructures found upon dorsal scales of the sandfish by comparing them with a closely related, non-sandswimming skink (Scincopus fasciatus) and resin replicas. Furthermore, we investigated further functions of these serrations, like infrared- and moisture harvesting and the prevention of triboelectric charges. We further provide a pathway towards exploitation the sandfish's skin abilities for future engineering applications.
Topological Evolution of a Fast Magnetic Breakout CME in Three Dimensions

We present the extension of the magnetic breakout model for CME initiation to a fully three-dimensional, spherical geometry. Given the increased complexity of the dynamic magnetic field interactions in three dimensions, we first present a summary of the well known axisymmetric breakout scenario in terms of the topological evolution associated with the various phases of the eruptive process. In this context, we discuss the analogous topological evolution during the magnetic breakout CME initiation process in the simplest three-dimensional multipolar system. We show that an extended bipolar active region embedded in an oppositely directed background dipole field has all the necessary topological features required for magnetic breakout, i.e., a fan separatrix surface between the two distinct flux systems, a pair of spine field lines, and a true three-dimensional coronal null point at their intersection. We then present the results of a numerical MHD simulation of this three-dimensional system where boundary shearing flows introduce free magnetic energy, eventually leading to a fast magnetic breakout CME. The eruptive flare reconnection facilitates the rapid conversion of this stored free magnetic energy into kinetic energy and the associated acceleration causes the erupting field and plasma structure to reach an asymptotic eruption velocity of ≳1100 km s−1 over an ~15 minute time period. The simulation results are discussed using the topological insight developed to interpret the various phases of the eruption and the complex, dynamic, and interacting magnetic field structures.
On nuclear reactions and Be-9 production in inhomogeneous cosmologies

Des reactions supplementaires au reseau de reactions nucleaires standards necessaires pour l'etude de la nucleosynthese primordiale dans des modeles cosmologiques inhomogenes sont presentees ainsi que les constantes de vitesse associees avec ces nouvelles reactions. En utilisant ce reseau de reactions, on montre que la production de 9 Be dans des modeles inhomogenes est fortement dependante du contraste de densite R et de la fraction volumique a haute densite fv. Il est suggere que 9 Be peut etre utilise comme un indicateur possible de l'inhomogeneite au moment de la nucleosynthese seulement pour une certaine etendue de fvR