Miracle-dz/UniFAR-FTUs huggingface dataset:
The structure of turbulent boundary layers

Extensive visual and quantitative studies of turbulent boundary layers are described. Visual studies reveal the presence of surprisingly well-organized spatially and temporally dependent motions within the so-called ‘laminar sublayer’. These motions lead to the formation of low-speed streaks in the region very near the wall. The streaks interact with the outer portions of the flow through a process of gradual ‘lift-up’, then sudden oscillation, bursting, and ejection. It is felt that these processes play a dominant role in the production of new turbulence and the transport of turbulence within the boundary layer on smooth walls. Quantitative data are presented providing an association of the observed structure features with the accepted ‘regions’ of the boundary layer in non-dimensional co-ordinates; these data include zero, negative and positive pressure gradients on smooth walls. Instantaneous spanwise velocity profiles for the inner layers are given, and dimensionless correlations for mean streak-spacing and break-up frequency are presented. Tentative mechanisms for formation and break-up of the low-speed streaks are proposed, and other evidence regarding the implications and importance of the streak structure in turbulent boundary layers is reviewed.
A mode-locked nanomechanical electron shuttle for phase-coherent frequency conversion

In this paper, we present the operation of an electron shuttle realized as a nanomechanical diode for phase-coherent frequency conversion. The mechanical response of the balanced resonator displays a hierarchy of frequency-locked resonances. We are able to achieve phase control via intrinsic frequency locking of the commensurate oscillations. By selecting the appropriate winding numbers, we can apply this nanomechanical resonator for radio-frequency conversion and rectification. The results also indicate that correlated electron shuttling and dividers for frequency combs can be realized with nanomechanical resonators.
Convergence of the Quadrature-Differences Method for Singular Integro-Differential Equations on the Interval

In this paper, we propose and justify the quadrature-differences method for the full linear singular integro-differential equations with the Cauchy kernel on the interval (–1,1). We consider equations of zero, positive and negative indices. It is shown that the method converges to an exact solution, and the error estimation depends on the sharpness of derivative approximations and on the smoothness of the coefficients and the right-hand side of the equation.
Root-locus method for the Tsypkin and Jury and Lee criteria†

A method is developed for application of the Tsypkin criterion and the Jury and Lee stability criteria for certain classes of non-linear sampled data systems The method, which uses root-locus techniques, is based on the root-locus interpretation of the Popov criterion for continuous data non-linear systems. This method was developed by Ramapriyan et al. (1966).
Aerodynamic vibration mechanism of HDD arms predicted by unsteady numerical simulations

With increases in recording density and higher rotation speeds, the aerodynamic aspect of hard disk drives (HDDs) is now quite significant. We studied the internal airflow of HDDs using a direct numerical simulation. We simulated two cases: the first had an arm with no weight-saving hole (no-hole case), while the second had an arm with a weight-saving hole (hole case). We observed periodic vortices (Karman type) for which the frequency was about 4 kHz in the downstream of the arm in both cases. The scale of the vortex in the hole case was larger than that in the no-hole case. In the hole case, the spectrum of the arm torque had sharp peaks that would directly affect the head positioning accuracy. Moreover, we found that there was no remarkable peak in the no-hole case.
Switched Bond Graphs : Simulation and Analysis

In this thesis an approach to modeling and simulation of mode switching systems is investigated. This approach, switched bond graphs, is an extension of the bond graph language in the sense that it allows modeling of mode switching phenomena.The classical bond graph language as well as the switched bond graph language are presented. Different aspects of these tools are discussed, and one aspect specially considered is causality. Computational causality shows in what order the variables in a model should be calculated to get efficient simulation code. Causality can also be used to analyze the model. For classical bond graphs, causality is a fixed property, but for switched bond graphs causality becomes mode varying.In classical bond graphs, algorithms for causality propagation, equation generation, and simulation are well established. Here, corresponding algorithms for switched bond graphs are derived. A causality propagation algorithm is presented, that detects causality problems like algebraic loops, derivative causalities and conflicting causalities. The algorithm checks all modes simultaneously, with a complexity that is proportional to the size of the bond graph, and not to the number of modes. A simulation algorithm is presented, that derives the information necessary for simulating a mode, when the mode is reached in a simulation run. This algorithm circumvents the combinatorial explosion in the number of modes. An algorithm for deriving the complete mathematical description from a bond graph is also given.The algorithms are analyzed, and their claimed functionality is proved. The proofs are based on properties of classical bond graphs. Then it is shown that a class of classical bond graphs can be expressed in state space form, by a variable transformation. For the same class of classical bond graphs, results are given, showing when an algebraic loop occurs, and what variables are included.These results are used to verify a part of the simulation algorithm. It is shown that correct initial values of the continuous state variables are achieved, when a new mode is entered during simulation of a switched bond graph. This problem is non-trivial since the mode varying causality may give rise to discontinuities in the state variables at a change of modes. It is also shown that the presented causality propagation algorithm for switched bond graphs detects all possible causal conflicts and derivative causalities, and the largest possible algebraic loops, in any mode.The initialization of modes is also analyzed in a singular perturbation theory framework, and this analysis verifies the correctness of the mode initialization algorithm.Finally, the simulation algorithm is applied to two examples.
Can a Moderate-Resolution Limited-Area Data Assimilation System Add Value to the Global Analysis of Tropical Cyclones?

AbstractThis study investigates the benefits of employing a limited-area data assimilation (DA) system to enhance lower-resolution global analyses in the northwest Pacific tropical cyclone (TC) basin. Numerical experiments are carried out with a global analysis system at horizontal resolution T62 and a limited-area analysis system at resolutions from 200 to 36 km. The global and limited-area DA systems, which are both based on the local ensemble transform Kalman filter algorithm, are implemented using a unique configuration, in which the global DA system provides information about the large-scale analysis and background uncertainty to the limited-area DA system. The limited-area analyses of the storm locations are, on average, more accurate than those from the global analyses, but increasing the resolution of the limited-area system beyond 100 km has little benefit. Two factors contribute to the higher accuracy of the limited-area analyses. First, the limited-area system improves the accuracy of the locat.
Observation of bistable resistance memory switching in CuO thin films

We report a bistable resistance switching behavior of CuO thin films. To understand the resistance switching mechanism, we have studied impedance spectroscopy and nanoscale electrical property. From the frequency-dependent impedance properties of CuO thin films in high resistance (ROFF) and low resistance (RON) states, we infer the formation of conducting paths generated by external bias as a possible origin of the bistable resistance states. In addition, the observation of inhomogeneous conducting path using a conducting atomic force microscope is also consistent with our inference.
Particle Swarm Optimization-Proximal Point Algorithm for Nonlinear Complementarity Problems

A new algorithm is presented for solving the nonlinear complementarity problem by combining the particle swarm and proximal point algorithm, which is called the particle swarm optimization-proximal point algorithm. The algorithm mainly transforms nonlinear complementarity problems into unconstrained optimization problems of smooth functions using the maximum entropy function and then optimizes the problem using the proximal point algorithm as the outer algorithm and particle swarm algorithm as the inner algorithm. The numerical results show that the algorithm has a fast convergence speed and good numerical stability, so it is an effective algorithm for solving nonlinear complementarity problems.
Numerical solution of fractional Sturm-Liouville equation in integral form

In this paper a fractional differential equation of the Euler-Lagrange/Sturm-Liouville type is considered. The fractional equation with derivatives of order α ∈ (0, 1] in the finite time interval is transformed to the integral form. Next the numerical scheme is presented. In the final part of this paper examples of numerical solutions of this equation are shown. The convergence of the proposed method on the basis of numerical results is also discussed.
THE INTEGER‐VALUED AUTOREGRESSIVE (INAR(p)) MODEL

Abstract. The integer-valued autoregressive (INAR) model with lag p dependence is discussed. The existence and ergodic property of the INAR model are proved. It is shown that the correlation structure of the INAR model is similar to that of the continuous-valued autoregressive (AR) process, and the stationary conditions of INAR and AR processes are also the same.
Rotationally modulated X-ray emission from the single O star ζ Ophiuchi

Archived measurements by the X-ray Telescope on board the ASCA satellite of the single runaway O9.5V star, ζ Ophiuchi, are analysed. The data set is unique as it covers just more than one full rotational period of the star. We report a clearly detected periodic X-ray flux variability with amplitude ~20% in the ASCA passband (0.5-10 keV). The detected period ${\sim} 0\fd77$ possibly indicates a connection with the recurrence time ($0\fd875\pm 0\fd167$) of the discrete absorption components (DACs) in UV spectra of the star, thought to be due to the presence of large scale structures in the stellar wind modulated by rotation. We attribute the X-ray fluctuation with an uneven distribution of X-ray absorbing material. We also report that an analysis of similar ASCA observations of ζ Puppis failed to confirm earlier reported variability of X-rays from this star based on Rosat observations.
Equilibria and evolutions of magnetized, rotating, isothermal clouds. II - the extreme case: nonrotating clouds

Equilibrium solutions of magnetized nonrotating clouds in a static external medium were obtained for a wide ranges of parameters. Two different equilibrium states with the same mass but different central densities were obtained, and it is shown that the solution with lower central density is stable, while that with higher central density is unstable. Two possibilities for the initiation of star formation are suggested: (1) the mass of cloud exceeds M(cr) and (2) the cloud is compressed beyond the unstable equilibrium solution with higher central density. 23 references.
Applications of near-infrared imaging

Focal plane arrays (FPAs) fabricated from the indium gallium arsenide (InGaAs) ternary alloy system exhibit high performance when operates at room temperature. Material considerations relevant to high device performance are discussed and the status of linear and two dimensional devices summarized. Examples of important imaging applications using InGaAs FPAs are presented.
The determination of ultraviolet extinction from the optical and near-infrared

The correlation of optical-near-infrared photometry for a sample of stars with well-determined ultraviolet extinction is examined. A good correlation is found; in particular, it is found that the value of total-to-selective extinction correlates well with the level of linear UV background extinction found from the UV curve parameterization of Fitzpatrick and Massa. An analytic expression is given for an improved estimate for the UV extinction law that can be obtained from optically determined values of R. For R values outside the range R = 3.1 -3.5, use of the analytic expressions given here will result in a more accurate representation of the applicable UV extinction than using the standard techniques of assuming the average curve or ironing out the bump. 19 references.
HREM contrast interpretation of pseudo‐symmetric structure regions in nanocrystalline germanium

The atomic structure of nanocrystalline particles formed by vapour deposition and subsequent annealing of amorphous thin films of germanium is studied by high resolution electron microscopy, image processing, and image simulation. The HREM images reveal a highly varied multiply twinned structure. In some regions of adjacent twins contrast features are detected that show pseudo-symmetric linear and circular superstructures of local non-crystallographic symmetry. These contrast features are caused by an overlapping of twin lamellae as is demonstrated by contrast simulations. The simulation procedure is carried out for different models of superimposed twins.
Zonal mean circulations for two conserved meridional coordinates

While many investigations of the atmospheric zonal mean circulation have been published using various vertical coordinates, this article concentrates on meridional coordinates other than latitude. Potential vorticity q and potential temperature θ are selected, with height as the vertical coordinate. Both q and θ are conserved in adiabatic frictionless flow. Although this helps in the interpretation of the results, both choices are problematic because of contortions in the contours. The related problems are solved by integrating over suitable zonal tubes.
On the Behaviour of the First Eigenfunction of the p‐Laplacian Near its Critical Points

In this paper, the behaviour of the positive eigenfunction φ of –Δpu= λ|u|p−2u in Ω u|∂Ω = 0, p > 1, is studied near its critical points. Under some convexity and symmetry assumptions on Ω, φ is seen to have a unique critical point at x = 0; also, the behaviour of both φ and ∇φ is determined nearby. Positive solutions u to some general problems −Δpu = f(u) in Ω, u|∂Ω = 0, are also considered, with some convexity restrictions on u. 2000 Mathematics Subject Classification 35B05 (primary), 35J65, 35J70 (secondary).
Noncontact and simultaneous measurement of the d33 and d31 piezoelectric strain coefficients

Here, digital image correlation is demonstrated to be an accurate tool for the noncontact, non-destructive, and rapid characterization of the converse effect of piezoelectric materials. The longitudinal (d33) and transverse (d31) piezoelectric strain coefficients of lead zirconate titanate-5H wafers are measured simultaneously by imaging the wafer's cross section. The results are validated through laser interferometry and the large piezoresponse at switching domains is observed in strain-electric field butterfly loops. The proposed technique is simple and low cost requiring only an optical microscope and unlike indirect measurement methods requires little sample preparation and no information regarding the mechanical properties of the specimen.
Defect generation in amorphous-indium-gallium-zinc-oxide thin-film transistors by positive bias stress at elevated temperature

We report on the generation and characterization of a hump in the transfer characteristics of amorphous indium gallium zinc-oxide thin-film transistors by positive bias temperature stress. The hump depends strongly on the gate bias stress at 100 °C. Due to the hump, the positive shift of the transfer characteristic in deep depletion is always smaller that in accumulation. Since, the latter shift is twice the former, with very good correlation, we conclude that the effect is due to creation of a double acceptor, likely to be a cation vacancy. Our results indicate that these defects are located near the gate insulator/active layer interface, rather than in the bulk. Migration of donor defects from the interface towards the bulk may also occur under PBST at 100 °C.
Preparation of Y‐Ba‐Cu oxide superconductor thin films using pulsed laser evaporation from high Tc bulk material

We report the first successful preparation of thin films of Y‐Ba‐Cu‐O superconductors using pulsed excimer laser evaporation of a single bulk material target in vacuum. Rutherford backscattering spectrometry showed the composition of these films to be close to that of the bulk material. Growth rates were typically 0.1 nm per laser shot. After an annealing treatment in oxygen the films exhibited superconductivity with an onset at 95 K and zero resistance at 85 and 75 K on SrTiO3 and Al2O3 substrates, respectively. This new deposition method is relatively simple, very versatile, and does not require the use of ultrahigh vacuum techniques.
Controllability and observability of linear time-varying impulsive systems

Many practical systems in physics, chemistry, biology, engineering, and information science have impulsive dynamical behaviors due to abrupt changes at certain instants during the dynamical processes. These complex dynamical behaviors can be modeled by impulsive differential systems. This paper studies the controllability and observability issues for a general time-varying impulsive control systems. Sufficient and necessary conditions for state controllability and state observability of the impulsive control systems are established and their applications to time-invariant impulsive control systems are also discussed. Furthermore, several new results associated with variation of parameters for time-varying impulsive control systems are derived.
Increased Stability in Crystal Growth Kinetics in Response to Bulk Transport Enhancement

High-resolution interferometry on facets of lysozyme crystals growing under steady external conditions revealed intrinsic kinetics instabilities that occur as fluctuations in the spacing of growth steps. The amplitude of these fluctuations is reduced by forced solution flow. This increased stability is interpreted in terms of the ratio of the characteristic rates of lattice incorporation and bulk transport. Apparently a steady state is approached as an asymptote of a continuous family of unsteady states.
Charge Transport In Zirconium Doped Anatase Nanowires Dye-Sensitized Solar Cells: Trade-Off Between Lattice Strain and Photovoltaic Parameters

Zirconium (Zr) is doped up to 5 at. % in anatase TiO2 nanowires by electrospinning and used as working electrode in dye-sensitized solar cells. Variations observed in the photovoltaic parameters were correlated by electrochemical impedance spectroscopy, open circuit voltage decay, and X-ray diffraction measurements. Results show that homovalent substitution of Zr in TiO2 increased the chemical capacitance and electron diffusion coefficient which in turn decreased charge transport resistance and charge transit time. However, lattice strain due to size mismatch between the Zr4+ and Ti4+ ions decreased open circuit voltage and fill factor thereby setting a trade-off between doping concentration and photovoltaic properties.
EFFECT OF NUMBERS OF COLONIES PER PLATE ON THE ESTIMATE OF THE BACTERIAL POPULATION IN SOIL

Numbers of colonies of bacteria on plates from two series of 36 plots were found to vary widely on one date of sampling and from day to day. In an attempt to determine the effect of this variation and of introducing a dilution of different strength during the progress of an experiment on the accuracy of estimates, samples were plated in a series of replicate dilutions, with three parallel plates from each. In Experiment 1, four replicate dilutions of one strength were used. The experiment was repeated 120 times and shows that parallel dilutions, prepared by a slightly altered technique, add only very little to the error of the experiment beyond that of the interaction. In Experiment 2, three replicate dilutions of 1:300,000; 1:400,000, and 1:500,000 strengths, respectively, were used. This experiment was repeated 162 times, yielding a final result similar to that from dilutions of one strength. In the third experiment three replicate dilutions of 1:150,000; 1:250,000, and 1:400,000 strengths, respectively.
Exploring the nature of Pacific climate variability using a ``toy'' nonlinear stochastic model

The Pacific Decadal Oscillation (PDO) is the leading mode of North-Pacific temperature variability. This climatic oscillation is nominally dominated by regime shifts having wide-ranging impacts. An ongoing point of discussion around the PDO regards whether such regimes genuinely represent multiple, stable, discrete states in a nonlinear dynamical system, or instead simply extended runs of above- or below-normal values in a continuous stochastic memory process. A simple nonlinear Markov time series model, involving a (hybrid) stochastically driven tipping-point process, is considered as a vehicle to explore the fundamental nature of the PDO. This toy model is found to be sufficiently plausible for our purposes, insofar as it reproduces some key observational PDO dynamics: in particular, de facto regime shifts and a 1/f power spectrum. The primary conclusion is that the line between the two competing general views may be blurred, and the red-noise and bi-stability hypotheses might be better considered as en.
A linear discretization of the volume conductor boundary integral equation using analytically integrated elements (electrophysiology application)

A method is presented to compute the potential distribution on the surface of a homogeneous isolated conductor of arbitrary shape. The method is based on an approximation of a boundary integral equation as a set of linear algebraic equations. The potential is described as a piecewise linear or quadratic function. The matrix elements of the discretized equation are expressed as analytical formulas. >
Effects of aerosols on trade wind cumuli over the Indian Ocean: Model simulations

An Eulerian non‐hydrostatic anelastic fluid model using a warm cloud bulk parametrization is used to study responses of trade wind cumuli to increased cloud drop concentrations produced by enhanced aerosol numbers and to absorption from aerosols containing soot. Simulations are initialized using temperature and moisture profiles measured during the Indian Ocean Experiment (INDOEX) and sea surface temperatures retrieved from the Tropical Rainfall Measuring Mission microwave imager. Cloud covers between 4 and 10% and cloud‐averaged liquid water contents of between 0.01 and 0.6 g m−3 more closely match values retrieved and measured in situ during INDOEX than those modelled in past studies; previous studies found larger cloud coverage associated with cloud spreading below a strong inversion not present in the INDOEX soundings.
Size-tunable infrared (1000–1600 nm) electroluminescence from PbS quantum-dot nanocrystals in a semiconducting polymer

Nanocomposites consisting of PbS nanocrystals in a conjugated polymer matrix were fabricated. We report results of photo- and electroluminescence across the range of 1000 to 1600 nm with tunability obtained via the quantum-size effect. The intensity of electroluminescence reached values corresponding to an internal quantum efficiency up to 1.2%. We discuss the impact of using different-length capping ligands on the transfer of excitations from polymer matrix to nanocrystals.