Approximate estimates of limiting errors of passive wireless SAW sensing with DPM

This paper discusses approximate statistical estimates of limiting errors associated with single differential phase measurement of a time delay (phase difference) between two reflectors of the passive surface acoustic wave (SAW) sensor. The remote wireless measurement is provided at the ideal coherent receiver using the maximum likelihood function approach. Approximate estimates of the mean error, mean square error, estimate variance, and Cramér-Rao bound are derived along with the error probability to exceed a threshold in a wide range of signal-to-noise ratio (SNR) values. The von Mises/Tikhonov distribution is used as an approximation for the phase difference and differential phase diversity. Simulation of the random phase difference and limiting errors also is applied.     

Thermal diffusivity of nanocarbon composites

This study was performed to measure the thermal diffusivity of different types of nanocarbon composites. Thermoexfoliated graphite (TEG), ultrasonically dispersed TEG, and multiwalled carbon nanotubes were used as fillers in epoxy polymer matrixes. The nanocarbon filler content was 1–10 wt%. The temperature dependence of the thermal conductivity and the heat capacity were extensively characterized in the temperature range between 150 and 425 K. For this purpose, the thermal diffusivity of the composites was investigated by two experimental methods: dynamic λ‐calorimeter and photoacoustic. The comparative analysis of thermal diffusivity of compacted TEG samples with different densities and of nanocarbon‐epoxy with different filler content was carried out. It was found that for the composites with a low distribution of the nanocarbon filler, the thermal diffusivity increases and that the value is determined by the structural and morphological properties of the filler. The orientation function for the TEG‐epoxy composites and the compact TEG samples differs due to the epoxy matrix that reduced anisotropy of the composite. POLYM. COMPOS., 2011. © 2010 Society of Plastics Engineers     

Probability density of the phase of a random RF pulse in the presence of Gaussian noise

In this paper, we show that the probability density function (pdf) of the phase of a random nonstationary radio frequency (RF) impulse signal perturbed by Gaussian noise does not depend on the multiple time derivatives of the signal amplitude and phase at a given time instance and is the Bennett's pdf. Employing this revealing, we derive an alternative form of the conditional pdf of the phase representing it with the von Mises/Tikhonov pdf conditional on the envelope, signal-to-noise ratio (SNR), and signal phase. We expend this new form to the Fourier series and investigate for the locked and unlocked reference phases. The error probability for the phase to exceed a threshold is also analyzed.     

Modification of Nonionic Vesicles by Adding Decanol and Functional Lanthanide Ions

Colloid systems modified by luminescent ions in situ are highly attractive for the design of new molecular architectures and adaptable for monitoring and visualizing soft drug delivery systems. This paper presents original results on the characterization of the self‐organization process and the structure of vesicles formed by tetraethylene glycol monodecyl ether (C₁₂EO₄) in the presence of lanthanide ions and decanol additives. Detailed characterization of surface activity, aggregation properties and microstructure of individual and mixed aggregates has been carried out based on surface tension, electron microscopy, small‐angle X‐ray scattering, dynamic light scattering analysis and fluorescence spectroscopy. The small‐angle scattering results in combination with quantum‐chemical calculations assume the multishell vesicle formation in C₁₂EO₄/C₁₀H₂₁OH/H₂O media. In the C₁₂EO₄ solution the presence of Ln(III) ions and decanol initiate the formation of multilamellar vesicles with a size of about 100 nm. The luminescence analysis of the Eu(III) and Tb(III) complexes has shown the efficient solubilization in the C₁₂EO₄/C₁₀H₂₁OH/H₂O vesicles, which leads to increase in the lifetime. The resulting outcome is the possibility to control micro and macro properties of a molecular organized system to give it the desired functionality.     

Efficient predictive estimator for holdover in GPS-based clock synchronization

This paper addresses an unbiased p-step predictive finite impulse response (FIR) filter of the local clock K-degree time interval error (TIE) polynomial model with applications to the global positioning system (GPS)-based clock synchronization. Generic coefficients are derived for a 2-parameter family of the polynomial filter gains. A generalization is provided for the p-step linear (ramp) gain allowing for close to optimal predictive filtering of the TIE. Basic holdover algorithms are discussed along with their most critical properties. Efficiency of the proposed filter in holdover is demonstrated by simulation and in real applications to GPS-based (sawtooth and sawtoothless) measurements of the TIE of a crystal clock.     

Coherent-interface-induced strain in large lattice-mismatched materials:A new approach for modeling Raman shift

Strain engineering as one of the most powerful techniques for tuning optical and electronic properties of Ⅲ-nitrides requires reliable methods for strain invest...     

Experimental analysis of the Poynting vector characteristics

The possibility of experimental measurement of the Poynting vector characteristics is shown. Under paraxial approximation, these characteristics may be obtained on the basis of local Stokes polarimetry and interferometry of electric field components. The experimental results for elliptically polarized Gaussian beam and heterogeneously polarized elementary fields are presented.     

Analysis of a Hyperbolic System Modelling the Thermoelastic Impact of Two Rods

The problem on collinear collision of two thermoelastic rods possessing the same rheological parameters but of different length and temperature is considered, in so doing before the impact the rods move unidirectionally along a common longitudinal axis with distinct constant velocities. Lateral surfaces and free ends of both rods are heat insulated, and free heat exchange between the rods occurs within contacting ends. The rods' thermoelastic behavior is described by the Green–Naghdy theory. Two methods are used as the methods of solution, namely: D'Alembert's method and the ray method. D'Alembert's method is based on the analytical solution of equations of the hyperbolic type describing the dynamic behavior of the thermoelastic rods. This solution involves four arbitrary functions which are determined from the initial and boundary conditions and are piecewise constant functions. The ray method is based on the theory of discontinuities and also allows one to obtain the solution involving four arbitrary constants. Both solutions complement each other, since D'Alembert's solution enables one to analyze the influence of thermoelastic parameters on the values to be found, while the solution via the ray method is best suited for numerical investigation of the longitudinal coordinate dependence of the desired values at each fixed instant of the time beginning from the moment of rods' collision up to the moment of their rebound. To illustrate the both approaches, the problem of the rods' collision without account for the stress and temperature fields coupling is also considered.     

Implementation of Digital Unbiased FIR Filters with Polynomial Impulse Responses

This paper addresses the design and implementation of digital unbiased finite impulse response (FIR) filters with polynomial impulse response functions. The transfer function, its fundamental properties, and a general block-diagram are discussed for the impulse response represented with the l-degree Taylor series expansion. As a particular results, we show a fundamental identity uniquely featured to such filters in the transform domain. For low-degree impulse responses, the transfer functions are found in simple closed forms and represented in compact block-diagrams. The magnitude and phase responses are also analyzed along with the group delays. A comparison with predictive FIR filters is given. As examples of applications, filtering of time errors of local clocks is discussed along with the low-pass filter design employing a cascade of the unbiased FIR filters.