Miracle-dz/UniFAR-FTUs huggingface dataset:
The field enhancement and optical sensing in the array of almost adjoining metal and dielectric nanorods

The surface plasmon (SP) excitations in the periodical array of the nanorods have attracted a lot of attention in the recent years due to the numerous potential applications in nanoplasmonics including transmitting and processing optical signals on a scale much smaller than the wavelength. In our work the plasmonic and dielectric systems consisting of twodimensional periodic arrays of nanorods are considered. We use computer simulation as well as exact analytical solution to find reflectance and transmittance the plane array of the nanorods, which have various diameters and inter-particle spacing. As the metal nanorods approach each other, series of surface plasmon resonances are excited. The resonances are strongly localized between nanorods due to its collective nature. It is shown that the local electric field is much enhanced in the interparticle gap and it concentrates at a scale much smaller than the diameter of the rod. The reflectance and transmittance have sharp minima and maxima corresponding to the excitation of various SP resonances. The computer simulations are in an agreement with our analytical theory. In the case of the dielectric nanorods the phenomenon of the whispering gallery modes effect is considered. The resonance frequencies and field enhancement can be tuned by variation of the shape and arrangement of the nanorods. The system of nanorods that almost touched each other by their generatrices can be used to develop plasmon and dielectric substrates, which are the basic elements of high sensitive SERS bio and chemical sensors.
Statistical analysis of catalogs of extragalactic objects. X. Clustering of 4C radio sources.

The radio source distribution in the 4C catalog is analyzed by the techniques used in previous papers in this series. The main results are: (1) The cross-correlation w/sub gr/(theta) between source positions and Lick galaxy counts is measured in some detail. (2) There is weak but apparently significant clustering among the sources themselves on scales of a few degrees. (3) The observed variation of w/sub gr/(theta) with flux level S shows that the differential radio luminosity function at the weak power end, 10/sup 23/< or approx. =Ph/sup 2/< or approx. =10/sup 25/W Hz/sup -1/sr/sup -1/ (H=100h km s/sup -1/Mpc/sup -1/) varies as approx.P/sup -1.3/ (4) The statistics are interpreted in terms of source-galaxy and source-source spatial correlation functions that have the same shape as the galaxy-galaxy function but amplitudes larger by factors 10.4 and 142. That is, 4C sources are not associated with galaxies at random, but rather tend to be found among strongly clustered galaxies.
Generalizations of Temple’s inequality

T. Kato's little-known generalization of a classic variational inequality for eigenvalues is extended to the case of normal operators and briefly discussed. It is usually not possible to evaluate precisely the eigenvalues of the linear operators which occur in realistic models in the physical sciences. It is thus a problem of great practical importance to have formulae for approximate evaluation of eigenvalues and for the errors of those approximations. The most important approximate formula for an eigenvalue is the Rayleigh-Ritz inequality, which gives an upper bound for the lowest eigenvalue of a selfadjoint operator. This is the prototype of a variational estimate, whereby a set of approximate eigenfunctions is guessed at and used to estimate the eigenvalues. The problem of obtaining lower bounds for the lowest eigenvalue of a selfadjoint operator is notoriously more difficult than the discovery of upper bounds, but some methods are widely known, though not so widely as the Rayleigh-Ritz inequality. The best such bound which relies only on the selfadjointness of the operator and the isolation of the lowest eigenvalue from the rest of the spectrum is due to G. Temple [7 Theorem 1]. The proofs of the Rayleigh-Ritz inequality and Temple's inequality show them to be straightforward applications of the spectral theorem [5], [6], and similar arguments can extend these inequalities to give useful estimates for any isolated eigenvalue of a selfadjoint operator-without the necessity of first estimating all the lower eigenvalues, as with the min-max principle. It is peculiar and unfortunate that more than two decades elapsed between Temple's original paper and the discovery of the generalization of Temple's inequality to arbitrary eigenvalues, and that this generalization has remained but little known for almost three more decades. In this paper Temple's inequality is generalized still further to the case of normal operators. Its use is not only for numerical computation, but also for the proofs of many abstract theorems about perturbation expansions and convergence of operator-valued functions [1], [2], [4], [5]. The classical result is Received by the editors February 18, 1977 and, in revised form, June 28, 1977. AMS (MOS) subject classifications (1970). Primary 47A10, 35P15.
Mechanisms of Intraseasonal Amplification of the Cold Siberian High

Mechanisms of intraseasonal amplification of the Siberian high are investigated on the basis of composite anomaly evolution for its strongest events at each of the grid points over Siberia. At each location, the amplification of the surface high is associated with formation of a blocking ridge in the upper troposphere. Over central and western Siberia, what may be called “wave-train (Atlantic-origin)” type is common, where a blocking ridge forms as a component of a quasi-stationary Rossby wave train propagating across the Eurasian continent. A cold air outbreak follows once anomalous surface cold air reaches the northeastern slope of the Tibetan Plateau. It is found through the potential vorticity (PV) inversion technique that interaction between the upperlevel stationary Rossby wave train and preexisting surface cold anomalies is essential for the strong amplification of the surface high. Upper-level PV anomalies associated with the wave train reinforce the cold anticyclonic anomalies at the surface by inducing anomalous cold advection that counteracts the tendency of the thermal anomalies themselves to migrate eastward as surface thermal Rossby waves. The surface cold anomalies thus intensified, in turn, act to induce anomalous vorticity advection aloft that reinforces the blocking ridge and cyclonic anomalies downstream of it that constitute the propagating wave train. The baroclinic development of the anomalies through this vertical coupling is manifested as a significant upward flux of wave activity emanating from the surface cold anomalies, which may be interpreted as dissipative destabilization of the incoming external Rossby waves.
A uniform diffusion limit for random wave propagation with turning point

A random wave propagation problem with turning point is considered for a refractive, layered random medium. The variations of the medium structure are assumed to have two spatial scales; microscopic random fluctuations are superposed upon slowly varying macroscopic variations. An extension of a limit theorem for stochastic differential equations with multiple spatial scales is derived and proved to obtain a uniformly valid diffusion limit for random multiple scattering up to the turning point region. The scale dependence of the infinitesimal generator of the backward Kolmogorov equation provides an insight into the interplay of internal refraction and random scattering as one approaches the turning point.
High-dielectric-constant all-polymer percolative composites

We report here an all-polymer high-dielectric (dielectric constant K>1000 at 1 kHz) percolative composite material, fabricated by a combination of conductive polyaniline particles (K>105) within a poly(vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene) terpolymer matrix (K>50). These high-K polymer hybrid materials also exhibit high electromechanical responses. For example, 1.5% strain, which is proportional to the square of the field applied, can be induced by a field of 9.5 MV/m, an eightfold reduction in field applied compared with that in a fluoroterpolymer matrix.
Linear Quadratic Optimal Cooperative Strategies for Active Aircraft Protection

Aircraft protection from a missile employing a known linear guidance strategy is considered. The aircraft protects itself by using a cooperating defensive missile. Depending on the available cooperation scheme, three different cooperative linear quadratic guidance strategies are derived and investigated for arbitrary-order linear-adversaries dynamics: 1) two-way cooperation, where the target–defender team employs its optimal cooperative strategy, 2) one-way cooperation, realized by the defender employing a classical one-on-one guidance law while the target helps by luring in the missile, and 3) one-way cooperation, realized by the target employing an arbitrary evasive strategy while the defender attempts to reach the predicted interception point. The performance of the three different cooperative strategies is compared and analyzed via simulation using the notion of Pareto fronts. It is shown that the performance of the target and the defender is highly dependent on the cooperation scheme. As expected, th.
Evaluation of Genetic Algorithm Concepts using Model Problems

A genetic algorithm approach suitable for solving multi-objective optimization problems is described and evaluated using a series of simple model problems. Several new features including a binning selection algorithm and a gene-space transformation procedure are included. The genetic algorithm is suitable for finding pareto optimal solutions in search spaces that are defined by any number of genes and that contain any number of local extrema. Results indicate that the genetic algorithm optimization approach is flexible in application and extremely reliable, providing optimal results for all optimization problems attempted. The binning algorithm generally provides pareto front quality enhancements and moderate convergence efficiency improvements for most of the model problems. The gene-space transformation procedure provides a large convergence efficiency enhancement for problems with non-convoluted pareto fronts and a degradation in efficiency for problems with convoluted pareto fronts. The most difficult problems --multi-mode search spaces with a large number of genes and convoluted pareto fronts-- require a large number of function evaluations for GA convergence, but always converge.
Propagation of nonplanar dust-acoustic envelope solitary waves in a two-ion-temperature dusty plasma

The evolution of the cylindrical and spherical dust-acoustic envelope solitary wave (DAESW) in an unmagnetized dusty plasma consisting of negatively charged dust fluid and ions of two different temperatures is investigated. By using the reductive perturbation method, the cylindrical and spherical geometry-modified nonlinear Schrodinger equation (GMNLSE) is obtained. The change of the DAESW amplitude due to the cylindrical and spherical geometry effects is deduced analytically. It is shown that there exist two time ranges. On the other hand, the wave amplitude changes with time τ as (τ0/τ)m/2 when the geometry effect is stronger and as (τ0/τ)m when the geometry effect is weaker, where τ0 is the initial time, and m=1 (2) refers to the cylindrical (spherical) case. The theoretical results are verified by the numerical calculation for the GMNLSE. The modulational instability of dust-acoustic waves governed by the GMNLSE is also presented. It is shown that the propagation of the DAESW in cylindrical geometry, .
Quantitative analysis based on the pair distribution function for understanding the anomalous liquid-structure change in In20Sn80

The temperature-induced anomalous liquid-structure change in melt ${\mathrm{In}}_{20}{\mathrm{Sn}}_{80}$ observed by Zu et al. [Phys. Rev. Lett. 89, 125505 (2002)] has been studied. The structure transition in ${\mathrm{In}}_{20}{\mathrm{Sn}}_{80}$ is further confirmed by the presence of an exothermic peak in the differential-scanning-calorimetry (DSC) curve. From experimental data of pair distribution functions, we calculated the viscosity $(\ensuremath{\eta})$ and the excess entropy $(S)$ and found that there is a valley of viscosity in the $\ensuremath{\eta}\text{\ensuremath{-}}T$ curve and a valley of excess entropy in the $S\text{\ensuremath{-}}T$ curve, which are consistent with the internal-friction $({Q}^{\ensuremath{-}1})$ peak in the ${Q}^{\ensuremath{-}1}\text{\ensuremath{-}}T$ curve and the exothermic peak in the DSC curve, respectively. We decomposed $S$ into two parts, $S(1)$ and $S(2)$, which are related to the total potential and the isothermal compressibility, respectively. The behaviors of $S(1)$ and $S(2)$ tell us that the atomic bonds vary twice and the microstructures transform twice in the temperature range from 300 to 900 \ifmmode^\circ\else\textdegree\fi{}C for liquid ${\mathrm{In}}_{20}{\mathrm{Sn}}_{80}$. The similar analysises of liquid ${\mathrm{In}}_{80}{\mathrm{Sn}}_{20}$ and liquid Sn reveal that Sn plays a crucial role in the discontinuous structure change in liquid ${\mathrm{In}}_{20}{\mathrm{Sn}}_{80}$.
On Advective Transport in Fractal Permeability and velocity Fields

We consider advective transport in a steady state random velocity field with homogeneous increments. Such a field is self-affine with a power law dyadic semivariogram γ(s) proportional to d2ω, where d is distance and ω is a Hurst coefficient. It is characterized by a fractal dimension D = E + 1 − ω, where E is topological dimension. As the mean and variance of such a field are undefined, we condition them on measurement at some point x0. We then introduce a tracer at another point y0 and invoke elementary theoretical considerations to demonstrate that its conditional mean dispersion is local at all times. Its conditional mean concentration and variance are given explicitly by well-established expressions which, however, have not been previously recognized as being valid in fractal fields. Once the conditional mean travel distance s of the tracer becomes large compared to the distance between y0 and x0, the corresponding dispersion and dispersivity tensors grow in proportion to s1+2ω, where 0 < ω < 1. This supralinear rate of growth is consistent with that exhibited by apparent longitudinal dispersivities obtained by standard methods of interpretation from tracer behavior observed in a variety of geologic media under varied flow and transport regimes. Filtering out modes from the fractal velocity field with correlation scales larger than some s0 allows an asymptotic transport regime to develop when s ≫ s0. The corresponding asymptotic dispersivities grow in proportion to s02ω, when 0 < ω ≤ ½. This linear to sublinear rate of growth is consistent with that exhibited by apparent longitudinal dispersivities obtained from calibrated numerical models in a variety of media. A self-affine natural log permeability field gives rise to a self-affine velocity field, while s is sufficiently small to insure that the variance of the log permeabilities, which grows as a power of s, remains nominally less than one. An analysis of published apparent longitudinal dispersivity data in light of the above theoretical results supports my earlier conclusion that when one juxtaposes data from a large number of generally dissimilar geologic media from a variety of locales, one observes a tendency toward self-affine behavior with a Hurst coefficient ω ≃ 0.25. At any given locale such media may or may not exhibit fractal behavior; if they do, ω may or may not be close to 0.25.
Constrained Indirect Estimation

We develop generalized indirect estimation procedures that handle equality and inequality constraints on the auxiliary model parameters by extracting information from the relevant multipliers, and compare their asymptotic efficiency to maximum likelihood. We also show that, regardless of the validity of the restrictions, the asymptotic efficiency of such estimators can never decrease by explicitly considering the multipliers associated with additional equality constraints. Furthermore, we discuss the variety of effects on efficiency that can result from imposing constraints on a previously unrestricted model. As an example, we consider a stochastic volatility process estimated through a garch model with Gaussian or t distributed errors. Copyright 2004, Wiley-Blackwell.
A note on stabilizing the Benjamin–Feir instability

In a recent paper, Segur et al. (J. Fluid Mech. vol. 539, p. 229, 2005, hereafter referred to as ${\cal S}$ showed, based on a damped version of the nonlinear Schrodinger equation (NLS), that any amount of dissipation (of a certain type) stabilizes the Benjamin–Feir instability of a modulated Stokes wave train. Their theoretical predictions are confirmed by laboratory experiments for waves of small or moderate amplitude, but not for waves of large amplitude or with relatively large perturbations. ${\cal S}$ left open questions regarding the validity of their theoretical results for these large-amplitude waves, and possibly the validity of the NLS assumptions of weak nonlinearity and narrow-bandedness. We investigate these issues using direct simulations of the primitive equations, incorporating constant and wavenumber-dependent dissipation models. For small or moderate amplitudes, our full simulations agree with the theory and experiments of ${\cal S}$. For large amplitudes, we find that it is primarily the form of the dissipation model, rather than the assumptions of NLS, that is responsible for the failure of ${\cal S}$'s theoretical predictions. Indeed, with an appropriate wavenumber-dependent dissipation model, both the full simulations and NLS obtain the correct evolution behaviour for large-amplitude waves. Finally, using direct and NLS simulations, we confirm the general conclusion of ${\cal S}$ for stabilization of the Benjamin–Feir instability over long-time wave train evolution.
Triphenylmethyl and triphenylsilyl based molecular glasses for photonic applications

Triphenylmethyl and triphenylsilyl structural fragments can be used to obtain glass forming, solution processable materials from polar chromophore molecules. Large number of compounds has been synthesized taking advantage of this approach, making it possible to identify some structure-property relations. Regarding the non-linear optical (NLO) properties of the given materials it is evident that triphenylmethyl groups help shielding unwanted NLO efficiency limiting dipolar interactions between polar chromophores in solid films. Chromophore stacking is still observed for compounds with large dipole momentum values. The glass transition temperatures of the compounds increase with the molecular weight for the studied material class, reaching values up to 130°C.
Enhancement of terahertz wave generation by cascaded χ^(2) processes in LiNbO_3

We demonstrate, to the best of our knowledge, a novel generation process of a terahertz (THz) electromagnetic wave via a noncollinear χ(2) process in LiNbO3 with a phase-front-controlled femtosecond Ti:sapphire laser pulse. Systematic measurements of both the THz electric field and the excitation transmitted through an LiNbO3 crystal at different excitation powers show that the maximum amplitude of the THz electric field increases nonlinearly above the critical input powers. This enhancement of optical rectification efficiency is attributed to the distortion of the excitation pulse shape via electro-optic (EO) phase modulation by the emitted THz wave. Actually, spectral line shapes of both the THz wave and the excitation pulse become broadened above the threshold, and they are well reproduced by numerical simulations with equivalent one-dimensionally mapped coupled equations in the frequency domain. This generation scheme shows potential optimization of further generation efficiency.
Theoretical Level Structure and Decay Dynamics of Nickel-like Ions: Search for Laser Lines in the Soft X-ray Domain

Multiconfiguration Dirac–Fock wave functions have been applied to study the level structure and transition probabilities of high-Z nickel-like ions in the range 74 ≤ Z ≤ 84. Several level crossings are found which strongly influence the decay dynamics of the excited ions and explain why some of these lines cannot (so easily) be observed for all elements along the isoelectronic sequence. For two selected ions, the role of configuration interactions and relaxation is explored by large-scale expansions.
A Beilinson-type theorem for coherent sheaves on weighted projective spaces

In the study of projective varieties it is customary to consider embeddings as projective spectra of graded rings not necessarily generated in degree 1 (cf., for instance, [5, 6, 9]). Therefore one considers coherent sheaves on weighted projective spaces and their classification. The aim of this paper is to extend to weighted projective spaces an important theorem by Beilinson, which describes the bounded derived category DbCoh n of coherent sheaves on (see [1–3]). In its more explicit form the theorem gives, for every coherent sheaf F on , two bounded complexes of vector bundles E• S and E • 3 which are “two-sided resolutions” of F (that is, their cohomology is F , concentrated in degree zero). Each term of E• S (respectively, of E • 3) is a finite direct sum of locally free sheaves of the form O n−j (respectively,  nj) for 0 ≤ j ≤ n, the number of copies of each such sheaf being given by the dimension of a suitable cohomology group of F ⊗ nj (respectively, of F ⊗ O n−j). If Q = q0; : : : ; qn is an n + 1-uple of positive integers (we assume that each of the qi is prime to the characteristic of the field , if this is not zero), the weighted projective space of type Q is the projective algebraic variety Q = Proj x0 0 ; : : : ; xn n : an important property of Q, which is essential for our purpose, is that Q is isomorphic to the quotient of n by an action of the finite abelian group μQ = /q0 × · · · × /qn . The way we obtain a version of Beilinson’s theorem on Q is based on the following idea: given a coherent sheaf F on Q, we apply Beilinson’s
Geometric theory of the grating

Geometric theory of the grating is developed, with special emphasis on the relation between the properties of holographic gratings and those of mechanically ruled gratings. The theory is applicable to practically all types of holographic and mechanically ruled gratings, including aspheric gratings. General expressions are given for the effective grating constant, the grating equation, the focal curves, and the light-path function. Possible applications of the theory to the design of aberration-corrected gratings are also described.
Transient rheology of solvent-responsive complex fluids by integrating microrheology and microfluidics

A new microrheology set-up which allows us to quantitatively measure the transient rheological properties of solvent-responsive complex fluids was constructed by integrating particle tracking microrheology and microfluidics. The dialysis cell consists of a reservoir, porous dialysis membrane, and sample chamber. Solvent molecules can freely diffuse between the reservoir and the sample chamber while macromolecular sample components are trapped in the sample chamber with a rigid semipermeable dialysis membrane. The design enables manipulation of the solvent composition in the sample chamber by simply switching the fluid composition in the reservoir. Validation experiments for solvent diffusion in the dialysis cell showed good agreement with numerical solutions of the transport equations and confirmed that the solvent composition in a sample can be changed in a controlled and predictable fashion within a few minutes due to the small device dimensions. For aqueous solutions of sodium alginate and sodium polys.