Powerful Nuclear Polarization of Rubber Carbide Micro as well as Nanoparticles

Considering that the actuation voltage was divided into Sm-PMN-PT and PZT layers, the inherent piezoelectricity of the Sm-PMN-PT thin film is expected to be higher. Optimization of the phase in the film by tuning the composition ratio also will further improve the piezoelectricity. We believe that this achievement is a great step to discover a giant piezoelectricity relaxor-based thin film beyond PZT for MEMS.In this work, we present gigahertz low-loss unidirectional acoustic focusing transducers in thin-film lithium niobate. The design follows the anisotropy of fundamental symmetric (S0) waves in X-cut lithium niobate. The implemented acoustic delay line testbed consisting of a pair of the proposed transducers shows a low insertion loss of 4.2 dB and a wide fractional bandwidth of 7.5% at 1 GHz. The extracted transducer loss is 1.46 dB, and the propagation loss of the S0 waves is 0.0126 dB/ [Formula see text]. The design framework is readily extendable to other acoustic modes, given consideration on the optimal orientation for power flow and electromechanical transduction.Vapor-cell devices based on microwave interrogation provide a stable frequency reference with a compact and robust setup. Further miniaturization must focus on optimizing the physics package, containing the microwave cavity and atomic reservoir. In this article, we present a compact cavity-cell assembly based on a dielectric-loaded cylindrical resonator. The loaded cavity resonating at 6.83 GHz has an external volume of only 35 cm3 and accommodates a vapor cell with 0.9-cm3 inner volume. The proposed design aims at strongly reducing the core of the atomic clock, maintaining, at the same time, high-performing short-term stability ( σy(τ) ≤ 5×10-13 τ-1/2 standard Allan deviation). The proposed structure is characterized in terms of microwave field uniformity and atom-field coupling with the aid of finite-element calculations. The thermal sensitivity is also analyzed and experimentally characterized. We present preliminary spectroscopy results by integrating the compact cavity within a rubidium clock setup based on the pulsed optically pumping technique. The obtained clock signals are compatible with the targeted performances. The loaded-cavity approach is, thus, a viable design option for miniaturized microwave clocks.The possibility of the development of MEMS devices based on the tunable ferroelectric film Ba 0.8Sr 0.2O3 properties under uniaxial deformation was studied theoretically. The thermodynamic model of the phase transitions for the film under uniaxial stress was constructed. The behavior of the material constants for the film in various phase states was investigated. The propagation properties of the surface acoustic wave (SAW) under the uniaxial stress were studied for the film located on the single-crystal silicon substrate. It was shown that the SAW resonance frequency changes within 3 MHz for the frequency of 274 MHz, and 9 MHz for the frequency of 512 MHz.To perform a complete scan of a small diameter pipe is difficult for two reasons. First, the beam directivity of the Lamb wave within a small diameter pipe is worse than that within a large diameter pipe. selleck kinase inhibitor Second, the circumferential range of the small diameter pipe is so limited that it can allow less transducer to be attached on its surface. That means the signals from various circumferential positions are difficult to obtain. This article reports a method that can scan damage within a small diameter pipe using a partially covered axially magnetized magnetostrictive patch transducer (AM-MPT) around the circumference of a pipe based on the analysis of the beam directivity of the MHz Lamb wave. The partially covered AM-MPT was moved around the circumference of a pipe for subsequent measurements to get signals from various circumferential positions. To trigger strong enough MHz Lamb wave, the circumferential coverage of the partially covered AM-MPT was not less than half of the circumference of the pipe, and the greater length-to-width ratio of the magnetostrictive patch was used. The analytical model of beam directivity of the Lamb wave was used to study the Lamb wave propagation in the rolled plate. Then the analytical model was modulated to evaluate the damage scan within a small diameter pipe. The experimental results supported the analytical model through different circumferential coverages of the transducer, and different sizes and axial positions of the damage. The proposed method was proven to have the potential to be applied to damage scans within a small diameter pipe.Piezoelectric resonators have been extensively used as filters, actuator, and sensors. The effective electromechanical coupling coefficient ( [Formula see text] is the most useful parameter to evaluate the electromechanical conversion efficiency of piezoelectric resonators. However, even for simple geometry piezoelectric resonators, such as disks, the coupling between different modes makes the resonant characteristics very complex. The coupling causes low electromechanical coupling efficiency of the intended mode. We propose a finite-element-based energy integration method to calculate [Formula see text] of piezoelectric resonators. This method is more accurate than the conventional resonance-antiresonance method and provides a powerful tool for the design optimization of pure mode resonators. A special case studied here is the fundamental thickness extensional (TE) mode of PZT-8 disks in the aspect ratio range of 2-20. Our results showed that multimode coupling near this mode can be greatly suppressed by modifying the edge surface of the disk to a convex shape. Such an optimized design could enhance [Formula see text] of the fundamental TE mode by as much as 10%-45% depending on the aspect ratio.Inspection is a key part of the asset management process of industrial plants and there are numerous plate-like structures that require inspection. Ultrasonic guided waves have been extensively used to detect various types of defect by monitoring reflected and transmitted signals because they enable faster screening of large areas. However, ultrasonic guided wave testing becomes difficult for very shallow, sharp defects as current inspection techniques suffer from a lack of sensitivity to such features. Previous studies, obtained by comparing various inspection techniques, suggest that the SH1 mode in particular, at around 3 MHz · mm, would be suitable when testing for shallow defects; however, it is clear that both the SH0 and SH1 modes can exist at this frequency-thickness product. This can complicate the inspection process and, therefore, limit defect detectability. This article investigates the possibility of a single-mode excitation of the SH1 mode at around 3 MHz · mm. The ability of this method toward detecting very shallow defects ( less then 10% cross-sectional thickness loss) has also been studied.