A class of random field memory models for mortality forecasting

This article proposes a parsimonious alternative approach for modeling the stochastic dynamics of mortality rates. Instead of the commonly used factor-based decomposition framework, we consider modeling mortality improvements using a random field specification with a given causal structure. Such a class of models introduces dependencies among adjacent cohorts aiming at capturing, among others, the cohort effects and cross generations correlations. It also describes the conditional heteroskedasticity of mortality. The proposed model is a generalization of the now widely used AR-ARCH models for random processes. For such a class of models, we propose an estimation procedure for the parameters. Formally, we use the quasi-maximum likelihood estimator (QMLE) and show its statistical consistency and the asymptotic normality of the estimated parameters. The framework being general, we investigate and illustrate a simple variant, called the three-level memory model, in order to fully understand and assess the effectiveness of the approach for modeling mortality dynamics.     

Velocity distribution of desorbing CO2 in CO oxidation on Pd(110) under steady-state conditions

The velocity and angular distributions of desorbing CO₂ in CO oxidation on Pd(110) were studied under the steady-state conditions with cross-correlation time-of-flight techniques. Sharp changes were found in both distributions at the switching point of the rate-determining step. The velocity curves involved fast and slow components. The fast one, which was suddenly suppressed at the switching point, showed a translational temperature from 2300 to 4000 K. The slow component was thermalized to the surface temperature. A rapid site switching for CO₂ formation is proposed, in which the fast component is formed on flat parts of the surface and the slow one is formed on structural defects.     

Circumferential wave in magneto-electro-elastic functionally graded cylindrical curved plates

Piezoelectric-piezomagnetic functionally graded materials (FGM), with a gradual change of the mechanical and electromagnetic properties, have greatly applying promises. Based on Legendre orthogonal polynomial series expansion approach, a dynamic solution is presented for the propagation of circumferential harmonic waves in piezoelectric-piezomagnetic FGM cylindrical curved plates. The materials properties are assumed to vary in the direction of the thickness according to a known variation law. The dispersion curves of the piezoelectric-piezomagnetic FGM cylindrical curved plate and the corresponding non-piezoelectric and non-piezomagnetic cylindrical curved plates are calculated to show the influences of the piezoelectricity and piezomagnetism. Electric potential and magnetic potential distributions are also obtained to illustrate the different influences of the piezoelectricity and piezomagnetism. Finally, a cylindrical curved plate at a different ratio of radius to thickness is calculated to show the influence of the ratio on the piezoelectric effect and piezomagnetic effect.     

Embedding of small samples for spark discharge atomic emission spectrometry

One approach to the analysis of small samples by means of an ordinary point-to-plane spark spectrometer is by embedding them in an electrically conductive material. In order to do so for steel samples of any shape, embedding in a pure tin ingot was found to be appropriate. This was carried out by putting them into a graphite crucible along with fairly large tin pieces, followed by heating above the melting point of tin. Thus the samples became firmly attached to the tin ingots. Grinding was easy despite the different hardness of steel and tin. With this procedure, samples of various types of steel gave correct analytical results upon sparking except for tin, provided that their diameter was at least 6 mm. The method is fast, cheap and more versatile than alternative ones.     

Effect of field-induced magnetic ordering on the electrical resistance of the frustrated magnet Au80Co20

Au₈₀Co₂₀ platelets were produced by solid-state quenching followed by furnace annealing and characterized by X-ray diffraction. Magnetization and magnetoresistance (MR) were measured from 2 to 265 K. Minima of the zero-field electrical resistance R₀(T) were observed at low temperatures (T_m≈20 K) in both as-quenched and annealed samples. These minima disappear upon applying a magnetic field. At low T, a negative MR is associated to strong frustration and a very short magnetic coherence length; at higher temperatures, a positive MR is also observed.     

Sound fields radiated from a linear phased array based on analytical solutions of transient elastic waves

Beam characteristics of a linear phased array transducer are critical to its engineering applications as well as to its design. This paper proposes a method for the theoretical calculation of ultrasound field radiated by a linear phased array coupled to an elastic solid by a longitudinal wave couplant. In this case, the ultrasound field can be determined by superposition of the exact and analytical solutions of transient elastic waves induced by a number of discrete line sources normally acting on an elastic half-space. Based on the theoretical calculation, this work investigated the influences of several important parameters in a linear array transducer, such as wave length, array size, ratio of element width to inter-element spacing, to the ultrasound field characteristics. Interesting phenomena and useful results are obtained, which provide fast and accurate guidance for linear phased array transducer design. It also satisfies diverse and specific demands for actual engineering testing using arrayed transducers.     

Weak form quadrature element analysis of Bickford Beams

In this paper the recently proposed weak form quadrature element method is applied to high order beam analysis. Differing from other numerical methods, only one element is needed in the weak form quadrature element analysis as long as the cross-section of the beam is constant or varies continuously. Flexural, vibrational and eigenbuckling analyses of homogeneous beams are performed based on the Bickford beam theory. Numerical examples are presented to illustrate the accuracy and efficiency of the developed method.     

Time-scaling analysis of lightning in Italy

The series of lightning measured during 2002 and 2003 in two areas of Italy, Lombardia (northern Italy) and Campania (southern Italy), has been deeply investigated to detect and quantify time-clustering structures by using several methods. Our results suggest the existence of time-clustering in the sequence of lightning time-occurrences, characterized by the presence of two scaling regions, respectively related with clustering effect inside a single thunderstorm and among successive thunderstorms.