Sub-sample displacement estimation from digitized ultrasound RF signals using multi-dimensional polynomial fitting of the cross-correlation function

A widely used time-domain technique for motion or delay estimation between digitized ultrasound RF signals involves the maximization of a discrete pattern-matching function, usually the cross-correlation. To achieve sub-sample accuracy, the discrete pattern-matching function is interpolated using the values at the discrete maximizer and adjacent samples. In prior work, only 1-D fit, applied separately along the axial, lateral, and elevational axes, has been used to estimate the sub-sample motion in 1-D, 2-D, and 3-D. In this paper, we explore the use of 2-D and 3-D polynomial fitting for this purpose. We quantify the estimation error in noise-free simulations using Field II and experiments with a commercial ultrasound machine. In simulated 2-D translational motions, function fitting with quartic spline polynomials leads to maximum bias of 0.2% of the sample spacing in the axial direction and 0.4% of the sample spacing in the lateral direction, corresponding to 38 nm and 1.31 μm, respectively. The maximum standard deviations were approximately 1% of the sample spacing in both the axial and the lateral directions, corresponding to 193 nm axially and 4.43 μm laterally. In simulated 1% axial strain, the same function fitting leads to mean absolute displacement estimation errors of 255 nm in the axial direction and 4.77 μm in the lateral direction. In experiments with a linear array transducer, 2-D quartic spline fitting leads to maximum bias of 458 nm and 6.27 μm in the axial and the lateral directions, respectively. These results are more than one order of magnitude smaller than those obtained with separate 1-D fit when applied to the same data set. Simulations and experiments in 3-D yield similar results when comparing 3-D polynomial fitting with 1-D fitting along the axial, lateral, and elevational directions.     

SVD-based digital image watermarking using complex wavelet transform

A new robust method of non-blind image watermarking is proposed in this paper. The suggested method is performed by modification on singular value decomposition (SVD) of images in Complex Wavelet Transform (CWT) domain while CWT provides higher capacity than the real wavelet domain. Modification of the appropriate sub-bands leads to a watermarking scheme which favourably preserves the quality. The additional advantage of the proposed technique is its robustness against the most of common attacks. Analysis and experimental results show much improved performance of the proposed method in comparison with the pure SVD-based as well as hybrid methods (e.g. DWT-SVD as the recent best SVD-based scheme).     

Experimental Study of Phased Array Beam Steering Characteristics

The influence of several geometric parameters of linear phased arrays was studied. A systematic approach using an automated testing assembly was used to assess the steering performance of the array in a solid medium. In addition to calibrating the transducer with respect to its steering accuracy, this arrangement provided a detailed study of the effects of steering angle, number of elements, inter-element spacing and array aperture on the beam directivity. The experimental results show good agreement quantitatively with the predicted steering characteristics.     

The Metabolic Efficacy of a Cannabidiolic Acid (CBDA) Derivative in Treating Diet- and Genetic-Induced Obesity

Obesity is a global medical problem; its common form is known as diet-induced obesity (DIO); however, there are several rare genetic disorders, such as Prader–Willi syndrome (PWS), that are also associated with obesity (genetic-induced obesity, GIO). The currently available therapeutics for treating DIO and GIO are very limited, and they result in only a partial improvement. Cannabidiolic acid (CBDA), a constituent of Cannabis sativa, gradually decarboxylates to cannabidiol (CBD). Whereas the anti-obesity properties of CBD have been reasonably identified, our knowledge of the pharmacology of CBDA is more limited due to its instability. To stabilize CBDA, a new derivative, CBDA-O-methyl ester (HU-580, EPM301), was synthesized. The therapeutic potential of EPM301 in appetite reduction, weight loss, and metabolic improvements in DIO and GIO was tested in vivo. EPM301 (40 mg/kg/d, i.p.) successfully resulted in weight loss, increased ambulation, as well as improved glycemic and lipid profiles in DIO mice. Additionally, EPM301 ameliorated DIO-induced hepatic dysfunction and steatosis. Importantly, EPM301 (20 and 40 mg/kg/d, i.p.) effectively reduced body weight and hyperphagia in a high-fat diet-fed Magel2^null mouse model for PWS. In addition, when given to standard-diet-fed Magel2^null mice as a preventive treatment, EPM301 completely inhibited weight gain and adiposity. Lastly, EPM301 increased the oxidation of different nutrients in each strain. All together, EPM301 ameliorated obesity and its metabolic abnormalities in both DIO and GIO. These results support the idea to further promote this synthetic CBDA derivative toward clinical evaluation in humans.     

Nanostructured micronized solid dispersion of crystalline-amorphous metronidazole embedded in amorphous polymer matrix prepared by nano spray drying

In this study metronidazole drug was encapsulated by hydroxypropyl methylcellulose and polyvinylpyrrolidone polymers from solutions using nano spray drying technology. The influence of the process parameters and formulation variables were investigated on product morhology and structure, production yield and entrapment efficiency. The use of surface active admixtures (polyvinyl alcohol, Tween-80 and Pluronic F68) increased the product yield substantially. The entrapped metronidazole was partially in crystalline and amorphous state in both amorphous polymers as confirmed by DSC and powder X-ray diffraction measurements. In the composites with hydroxypropyl methylcellulose the degree of crystallinity was between 50.2 and 81.0%, and with polyvinylpyrrolidone between 35.0 and 50.0% (with respect to the drug content). Melting point decrease phenomena was observed by differential scanning calorimetry between bulk metronidazole and spray dried products. Peak broadening was indicated by powder X-ray diffraction measurements, which could be the result of formation of small drug crystallites. The TEM images showed beside the larger crystals (200–400 nm) a fraction of smaller crystals (20–50 nm in diameter), which are in good correlation with the calculated coherent scattering domain sizes of 19–87 nm based on X-ray data. The drug-polymer composites produced by nano spray drying process were identified as crystalline-amorphous nanostructured micronized solid dispersions.     

A Novel Actuator Fault-tolerant Control Strategy of DFIG-based Wind Turbines Using Takagi-Sugeno Multiple Models

International Journal of Control, Automation and Systems - In this paper, a new combined fuzzy observer-based fault-tolerant tracking control scheme is proposed for a doubly fed induction generator...     

Dynamic interface velocity for junction characterization

A dynamic velocity at the n-p junction interface has been introduced. Solar cell structures have been used as diode models. The relationship of the dynamic velocity with the technological parameters of solar cells and with the junction operating conditions has been considered. The variations of this dynamic velocity with the potential at the junction point out the influence of the base doping level and of the base width, and allow to differentiate the nature of the cell back contact.     

High-Resolution Electron Microscopy of Silicon Carbide-Whisker-Reinforced Alumina Composite Interfaces in Specimens Subjected to Elevated Temperatures

Interfaces of silicon carbide-whisker-reinforced alumina (SiC( w )/Al₂O₃) composites were examined using high-resolution electron microscopy (HREM). HREM specimens were prepared from the bulk of samples that were previously tested for fracture toughness at 25°, 1000°, 1200°, or 1400°C, in ambient air. The test temperature history served as an independent variable. It was found that the as-received material did not possess a distinct interfacial layer and that the test temperature history (which included a 30°C/min heating and cooling rate, a 30-min soak prior to specimen loading, and a typical test duration of 5–10 min) did not appreciably change the interface thickness at any of the elevated test temperatures.