Quadratic model updating with gyroscopic structure from partial eigendata

Quadratic eigenvalue model updating problem, which aims to match observed spectral information with some feasibility constraints, arises in many engineering areas. In this paper, we consider a damped gyroscopic model updating problem (GMUP) of constructing five n-by-n real matrices M,C,K,G and N, such that they are closest to the given matrices and the quadratic pencil Q(λ):=λ ² M+λ(C+G)+K+N possess the measured partial eigendata. In practice, M,C and K, represent the mass, damping and stiffness matrices, are symmetric (with M and K positive definite), G and N, represent the gyroscopic and circulatory matrices, are skew-symmetric. Under mild assumptions, we show that the Lagrangian dual problem of GMUP can be solved by a quadratically convergent inexact smoothing Newton method. Numerical examples are given to show the high efficiency of our method.     

Doping Dependence of the Effects of In-Plane Disorder on T c and the Pseudogap in Single Layer La214 and Double Layer Y123: a Comparative Study

High-T _c emerges from an strongly electronically correlated normal state in hole doped cuprates. In this paper, the comparative effect of Zn on the superconducting transition temperature, T _c , was studied for the La_2?x Sr _x Cu_1?y Zn _y O₄ (Zn-La214) and YBa₂(Cu_1?y Zn _y )₃O_7?δ (Zn-Y123) compounds as a function of hole concentration, p, and Zn content (y) in order to explore the interplay among different electronic ground states in different cuprate systems. Zn induced rate of suppression of T _c , dT _c (p)/dy, for Zn-La214 was found to be strongly p-dependent and showed a monotonic variation, except in the vicinity of p～0.125 (i.e., near the 1/8th anomaly where the charge/spin stripe correlations are at their strongest). Magnitude of dT _c (p)/dy decreased markedly around p～0.125. The same feature, at a somewhat reduced scale, was also observed for Zn-Y123. We have also reviewed the p-dependent pseudogap energy scale, ε _g (p), which shows a quasilinear decrease with increasing p, without any noticeable feature at p～0.125. The magnitude and the evolution of ε _g (p) are quite similar for both Zn-La214 and Zn-Y123 compounds even though T _c and structural and electronic anisotropies are significantly different.     

Frequency and Voltage Dependence of Dielectric Loss of MgB2 Composites at Different Temperatures

The dielectric loss (ε″) properties of MgB₂ composites were investigated by using the conductance–voltage (G/w–V) measurements in the wide frequency and applied bias voltage range at four different temperature levels. Experimental results show that both G/w and ε″ are found strong functions of frequency and applied bias voltage for each temperature level. These changes in G/w and ε″ are considerably high especially at low frequencies and temperatures. The values of ε″ decrease exponentially with increasing frequency until 100 kHz and then become almost constant. Such behavior of G/w and ε″ shows that interfacial polarization is more effective especially at low frequencies. In addition, the current–voltage (I–V) characteristics were also evaluated for 100, 200, and 300 K, and the I–V curves for each temperature show linear behavior. Results indicate that the G/w–V measurements may be a useful tool to characterize the dielectric properties and conductivity of MgB₂.     

Parameter representation of fatigue crack growth

From the study of the crack propagation data in fatigue, a parameter in the form P = mlogδK + C has been suggested, where the slope m and the intercept C are functions of the variables like stress ratio R, frequency w, and temperature T. Case studies where data are available for various stress ratios have been made and a Master Curve connecting the crack propagation rate da/dN and the parameter P has been obtained. Experimental data for various values of δK and R have been found to agree well with the theoretical prediction.     

Magnetic Transport Properties in GdBa2Cu3?x Ru x O7?δ Superconducting Phase

Bulk superconducting samples of type GdBa₂Cu_3?x Ru _x O_7?δ phase, Gd-123, with?x ranging from 0.0 to 0.15 were prepared by the conventional solid-state reaction technique. X-ray powder diffraction (XRD) and the electrical resistivity measurements were performed in order to investigate the effect of Ru⁴⁺ ions substitution on Gd-123 phase. Enhancement of the phase formation and the superconducting transition temperature T _c for GdBa₂Cu_3?x Ru _x O_7?δ phase up to x=0.05 was observed. The effect of magnetic field up to 4.4?kG on the electrical resistivity behavior of the prepared samples was studied to investigate the flux motion of this phase. The derived flux pinning energy?U, based on the thermally activated flux creep TAFC model, decreased with increasing the magnetic field?B. The flux pinning energy followed the exponent behavior as U(B)～B ^?β . The superconducting transition width ΔT increased as the magnetic field increased, showing the scaling relation as ΔT～B ⁿ . Using Ambegaokar and Halperin AH theory, the magnetic field and temperature dependence of U was found to be U(B,T)～ΔTB ^?η , η=β+n. The critical current density J _c (0) enhanced up to x=0.05, beyond which it decreased with further increase in Ru-content.     

Tables of the Inverse Laplace Transform of the Function [... formula ...]

The inverse transform, g(t) = ?^?1(e^?sβ), 0 < β < 1, is a stable law that arises in a number of different applications in chemical physics, polymer physics, solid-state physics, and applied mathematics. Because of its important applications, a number of investigators have suggested approximations to g(t). However, there have so far been no accurately calculated values available for checking or other purposes. We present here tables, accurate to six figures, of g(t) for a number of values of β between 0.25 and 0.999. In addition, since g(t), regarded as a function of β, is uni-modal with a peak occurring at t = t_max we both tabulate and graph t_max and 1/g(t_max) as a function of β, as well as giving polynomial approximations to 1/g(t_max).     

Elastic moduli of laminated composites revisited by using statistical analysis

In this article, an investigation of Young's modulus E, shear modulus G, Poisson's ratio ν and bending rigidity D for a general class of randomly oriented composite laminate is presented. A simple random statistical analysis has been used to demonstrate that the mean values of E, G, ν and D in the randomly oriented laminate are close to those analytical values obtained from the classical lamination theory. Also, the influences of the various lamina material properties E₂/E₁, G₁₂/E₁ and ν₁₂ to the values of E, G, ν and D of the laminate are investigated. The results from this statistical analysis provide a set of general guidelines for designing the values of E, G, ν and D of the randomly oriented composite laminates based on the given values of the influence factors E₂/E₁, G₁₂/E₁ and ν₁₂.     

Unitary Thermodynamics from Thermodynamic Geometry

Degenerate Fermi gases of atoms near a Feshbach resonance show universal thermodynamic properties, which are here calculated with the geometry of thermodynamics, and the thermodynamic curvature R. Unitary thermodynamics is expressed as the solution to a pair of ordinary differential equations, a “superfluid” one valid for small entropy per atom z≡S/Nk _B , and a “normal” one valid for high z. These two solutions are joined at a second-order phase transition at z=z _c . Define the internal energy per atom, in units of the Fermi energy, as Y=Y(z). For small z, Y(z)=y ₀+y ₁ z ^α +y ₂ z ^2α +?, where α is a constant exponent, y ₀ and y ₁ are scaling factors, and the series coefficients y _i (i≥2) are determined uniquely in terms of (α,y ₀,y ₁). For large z the solution follows if we also specify z _c , with Y(z) diverging as z ^5/3 for high z. The four undetermined parameters (α,y ₀,y ₁,z _c ) were determined by fitting the theory to experimental data taken by a Duke University group on ⁶Li in an optical trap with a Gaussian potential. The very best fit of this theory to the data had α=2.1, z _c =4.7, y ₀=0.277, and y ₁=0.0735, with χ ²=0.95. The corresponding Bertsch parameter is ξ _B =0.462(40).     

Presence and Antimicrobial Susceptibility of RE-cmeABC-Positive Campylobacter Isolated from Food-Producing Animals, 2014–2016

Campylobacter spp. are the leading cause of human gastroenteritis worldwide. RE-CmeABC is a newly identified resistance-enhancing multidrug efflux pump of Campylobacter spp. (C. spp.) that confers high-level resistance to fluoroquinolones, phenicols, macrolides, and tetracyclines (TETs), all of which are critical drugs in both human and veterinary medicine. In this study, we analyzed the presence and antimicrobial susceptibility of RE-cmeABC-positive Campylobacter isolates of food-animal origin from three representative regions (Shandong, Shanghai, and Guangdong) in China over three successive years, from 2014 to 2016. A total of 1088 Campylobacter isolates (931 C. coli and 157 C. jejuni) were recovered from the RE-cmeABC screening. We detected 122 (11.2%) RE-cmeABC-positive isolates of chicken origin, including 111 (70.7%) C. jejuni and 11 (1.2%) C. coli. This multidrug efflux pump is more prevalent among C. jejuni than C. coli. The level of resistance was significantly different in 111 RE-cmeABC-positive C. jejuni versus 46 RE-cmeABC-negative C. jejuni for florfenicol, clindamycin, and erythromycin (P < 0.05), but not for ciprofloxacin (CIP), TET, and gentamicin (GEN). However, the isolates harboring RE-cmeABC could shift the minimum inhibitory concentration distribution to the higher range for CIP and TET. Pulsed-field gel electrophoresis (PFGE) analysis suggested that horizontal transmission might be involved in the dissemination of RE-cmeABC in Shanghai and Guangdong, while clonal expansion was predominant in Shandong. Three isolates shared the indiscriminate PFGE types of RE-cmeABC-positive C. jejuni isolates in Shanghai and Guangdong, and four isolates in Shanghai and Shandong. Our study suggests the possibility of a wide dissemination of RE-cmeABC in Campylobacter of food-animal origin, which would pose a significant threat to public health.     

Transport properties of oxygen-deficient YBa2Cu3O7−x thin films

We report on measurements of the in-plane resistivityρ and Hall coefficientR _H (B∥c) of various oxygen-deficient epitaxial films of YBa₂Cu₃O_7?x in the normal state. The superconducting transition temperaturesT _c of the samples vary from 14 to 90 K. Both the resistivity and the Hall coefficient exhibit a strong dependence on the oxygen content and the temperature. Asx increases,T _c decreases continuously, whileρ andR _H gradually increase in magnitude. Furthermore, also the characteristic linear dependences ofραT andR _Hα T ^?1 of the highly doped compounds changes to a nonlinear behavior for the samples withT _c lower than 60 K. The unusual doping and temperature dependence ofR _H will be compared to the predictions of our calculations, based on a two-dimensional tight-binding model using the relaxation-time approximation. The model considers also the next-nearest-neighbor hopping, which strongly influences the predicted Hall coefficient. Additionally, the cotangent of the Hall angle cot(Θ _H ) is discussed in the framework of the two-dimensional Luttinger liquid theory.     

The small-angle scattering correlation function of two infinitely long parallel circular cylinders

The correlation function γ(r,d,s) of a pair {A,B} of infinitely long parallel circular cylinders of diameter d, the centers of which are separated by a distance s, is investigated. Based on first principles, two basic constellations (widely separated cylinders and close cylinders) are analyzed. Integral representations were obtained, applications of which are in the field of the interpretation of scattering experiments of the so-called controlled porous glasses (nearly cylindrical macropores in the region of 100 nm) and of pattern recognition of geometric figures. Series expansions of γ(r) at r=0 and the behavior of γ″(r) are analyzed for the special case s=d.     

Energy Spectrum of the Superfluid Velocity Made by Quantized Vortices in Two-Dimensional Quantum Turbulence

We discuss the configurations of vortices in two-dimensional quantum turbulence, studying energy spectrum of superfluid velocity and correlation functions with the distance between two vortices. We apply the above method to quantum turbulence described by Gross-Pitaevskii equation in Bose-Einstein condensates. We make two-dimensional quantum turbulence from many dark solitons through the dynamical instability. A dark soliton is unstable and decays into vortices in two- and three-dimensional systems. In our work, we propose a method of discriminating between the uncorrelated turbulence and the correlated turbulence. We decompose the energy spectrum into two terms, namely the self-energy spectrum E _self (k) made by individual vortices and the interactive energy spectrum E _int (k) made by interference of two vortices. The uncorrelated turbulence is defined as turbulence with E _int (k)?E _self (k), while the correlated turbulence is turbulence where E _int (k) is not much smaller than E _self (k). Our simulations show that in the decay of dark solitons, the vortices created consist of correlated pairs of opposite circulation vortices, leading to the correlated turbulence.     

Unsteady free convective boundary-layer flow near a stagnation point in a heat-generating porous medium

The free convection boundary-layer flow near a stagnation point in a porous medium is considered when there is local heat generation at a rate proportional to (T ? T _∞) ^p , (p ≥ 1), where T is the fluid temperature and T _∞ the ambient temperature. Two cases are treated, when the surface is thermally insulated and when heat is supplied at a constant (dimensionless) rate h _s from the boundary. If h _s = 0 the solution approaches a nontrivial steady state for time t large in which the local heating has a significant effect when p ≤ 2. For p > 2 the effects of the local heating become increasingly less important and the solution dies away, with the surface temperature being of O(t ^?1) for t large. When h _s > 0 and there is heat input from the surface, the solution for p ≤ 2 again approaches a nontrivial steady state for t large and all h _s . For p > 2 there is a critical value h _s,crit (dependent on the exponent p) of h _s such that the solution still approaches a nontrivial steady state if h _s < h _s,crit. For h _s > h _s,crit a singularity develops in the solution at a finite time, the nature of which is analysed.     

Electrical properties of TeAsGe films

The effect of temperature T, electrode separation d and substrate temperature T_s on the I–V characteristics of amorphous films 3500 Å thick, vapour deposited from the alloy TeAsGe (53:36:11 at. %) onto a glass substrate at room temperature, were investigated. The material displayed the behaviour of a negative resistance device with a memory. The behaviour for T=constant is described by the relation V = CIexp (?αI), where C and α are constants for a specimen at constant temperature. The threshold voltage at which the off state transforms to the negative resistance state decreased with T according to the relation V_th = V₀exp (E_v/2 kT), where E_v = 0.21 eV. V_th increased with d and decreased with T_s and was related to changes in resistance and structure. Microscope examination showed the formation of filaments containing recrystalized structure arising from Joule heating.     

A Comparative Analysis of the Chloroplast Genomes of Four Salvia Medicinal Plants

Herbgenomics is an emerging field of traditional Chinese medicine (TCM) research and development. By combining TCM research with genomics, herbgenomics can help to establish the scientific validity of TCM and bring it into wider usage within the field of medicine. Salvia Linn. (S. Linn.) is a large genus of Labiatae that includes important medicinal plants. In this herbgenomics study, the complete chloroplast (cp) genomes of two Salvia spp.—namely, S. przewalskii and S. bulleyana, which are used as a surrogate for S. miltiorrhiza—were sequenced and compared with those of two other reported Salvia spp.—namely, S. miltiorrhiza and S. japonica. The genome organization, gene number, type, and repeat sequences were compared. The annotation results showed that both Salvia plants contain 114 unique genes, including 80 protein-coding, 30 transfer RNA (tRNA), and four ribosomal RNA (rRNA) genes. Repeat sequence analysis revealed 21 forward and 22 palindromic sequences in both Salvia cp genomes, and 17 and 21 tandem repeats in S. przewalskii and S. bulleyana, respectively. A synteny comparison of the Salvia spp. cp genomes showed a high degree of sequence similarity in the coding regions and a relatively high divergence of the intergenic spacers. Pairwise alignment and single-nucleotide polymorphism (SNP) analyses found some candidate fragments to identify Salvia spp., such as the intergenic region of the trnV–ndhC, trnQ–rps16, atpI–atpH, psbA–ycf3, ycf1, rpoC2, ndhF, matK, rpoB, rpoA, and accD genes. All of the results—including the repeat sequences and SNP sites, the inverted repeat (IR) region border, and the phylogenetic analysis—showed that S. przewalskii and S. bulleyana are extremely similar from a genetic standpoint. The cp genome sequences of the two Salvia spp. reported here will pave the way for breeding, species identification, phylogenetic evolution, and cp genetic engineering studies of Salvia medicinal plants.     

Transport properties of Nd1.85Ce0.15 δ single crystals: The narrow-band model

The anisotropy of the resistivity and thermoelectric power (TEP)S of Nd_1.85Ce_0.15CuO_4?δ single crystal (T _c =17 K) has been investigated. In the temperature rangeT _c <T<300 K the ratioρ _c/ρ_ab≈10⁴ and the dependencesρ _ab (T) andρ _c (T) change from quadratic to linear atT～200 K. The dependencesS _ab (T) andS _c (T) reach a maximum atT>T _c and then decrease almost linearly with increasing temperature, changing sign from positive to negative nearT～ 150 K. The features of the resistivity and TEP temperature dependences (the lawρ∝T ² changing toρ∝T, the change in the sign of S with temperature, and the low TEP anisotropy at largeρ anisotropy) have been interpreted in the framework of the narrow-band model.     

A study about Ji,and δi,in three-point bend specimens with deep and shallow notches

An experimental study for determining δ_i, and J_i, in three-point bend specimens with both shallow and deep notches has been described. A new method for obtaining δ_i is simply introduced. Two clip gauges were used, P-V and P-Δ plots were simultaneously obtained on the same specimen. COD values were obtained from both P-V and P-Δ plots. Experimental results of three different heat-treated alloy steels show that the crack opening displacement and J-integral values of shallow cracks at initiation are much larger than those of deep cracks. The relationship of COD and J-integral is also studied.     

The shock forced oscillator model: A harmonic approximation

A new model is proposed for calculating the probability W _i→f of transition of a quantum system in the field of external force F from stationary state i to stationary state f—the shock forced oscillator model (SFO). The SFO model is based on the quantum theory of strong perturbations and allows one to estimate probabilities W _i→f for the transitions from level i to level f in the quantum system “diatomic molecule AB—structureless particle M.” It is shown that within the harmonic approximation to the SFO model (SFHO) and the model of a forced harmonic oscillator (FHO), probabilities W _i→f for the transition from stationary state i into some new state f are equal. In the harmonic approximation corresponding to the model SFHO, probabilities W _i→f for the transitions from level i to level f depend on the squared force parameter characterizing the force action of a structureless particle M on the diatomic molecule AB. In addition, we compare transition probabilities W _i→f calculated using the Morse potential, the classical Lennard-Jones potential, and the “improved” Lennard-Jones potential (with the ? parameter corresponding to the FHO model) in the system N₂-N₂. We propose to use this model at temperatures above 5000 K.     

Near-wake flow characteristics of two side-by-side circular cylinders close to a wall

Flow characteristics in the near wake of two identical side-by-side circular cylinders located close to a fully developed turbulent boundary layer are investigated experimentally using the particle image velocimetry (PIV) and the pressure sensor. The Reynolds number based on the cylinder diameter (D) is 1,696, the boundary layer thickness is 6.6 D, the cylinder center-to-center spacing (T) is varied from T/D = 1 to 1.906, and the gap spacing between the lower cylinder and the wall (G) is varied from G/D = 0 to 1.811. To study the effects of changing the gap ratios of T/D and G/D on the wake flow, various wake characteristics such as averaged streamlines, Reynolds stress and vorticity contours as well as other key flow features including the length scales and the Strouhal number are investigated for different ratios of T/D and G/D. According to these wake characteristics, five basic flow patterns have been identified.