Resonance Characteristics Research Articles

Vibrational line shape effects in plasmon-enhanced stimulated Raman spectroscopies.

A density matrix treatment of plasmon-enhanced (PE) stimulated Raman spectroscopies is developed. Specifically, PE stimulated Raman Gain/Loss (PE-SRG/L) and coherent anti-Stokes Raman scattering (PE-CARS) due to monochromatic excitation and PE femtosecond stimulated Raman spectroscopy (PE-FSRS) are considered. A Lorentz oscillator model is used to explicitly describe the time dependence of plasmon-enhanced optical fields. These temporal characteristics are required for a density matrix based description of all plasmon-enhanced nonlinear molecular spectroscopies. Dispersive vibrational line shapes in PE-SRG/L and PE-FSRS spectra are shown to result primarily from terms proportional to the square of the complex optical field enhancement factor. The dependence on the plasmon resonance, picosecond and femtosecond pulse characteristics, and molecular vibrational properties are evident in the density matrix derived PE-FSRS intensity expression. The difference in signal detection mechanisms accounts for the lack of dispersive line shapes in PE spontaneous Raman spectroscopy. This density matrix treatment of PE-FSRS line shapes is compared with prior coupled wave results.

Predicting Subtype of Growth Hormone Pituitary Adenoma based on Magnetic Resonance Imaging Characteristics.

This study aimed to investigate the value of magnetic resonance (MR) characteristics in differentiating the subtypes of growth hormone pituitary adenomas. The clinical and MR imaging data of 70 patients with growth hormone pituitary adenoma confirmed by surgery and pathology were retrospectively analyzed. The tumors were divided into dense granular (DG; 36 cases) and sparse granular subtypes (SG; 34 cases). The tumors' MR features were analyzed, including the mean and maximum diameters, T2 signal intensity, T2 relative signal intensity (rSI), homogeneity, enhancement degree, and invasiveness (Knosp grade). Mann-Whitney U test and χ2 test were used to analyze MR characteristics between the 2 groups. The independent predictors and predictive probabilities of tumor subtypes were obtained via a logistic regression model, and the efficacy was compared by receiver operating characteristic curve. The mean and maximum diameters of growth hormone adenoma in DG and SG were 1.77 versus 2.45 and 1.95 versus 3.00 cm (median, P < 0.05), respectively. There was a significant difference between the 2 groups in T2 signal intensity and rSI (P values were 0.02 and 0.001, respectively). Most DG adenomas (86.1%) appeared as hypointense on T2 images, and 38.2% of SG adenomas were hyperintense. There was no significant difference in tumor homogeneity (P = 0.622). A significant difference was found in the Knosp grade between the 2 subtypes (P = 0.004). In addition, the enhancement degree of SG adenomas was significantly higher than that of DG adenomas (P = 0.001). Logistic regression analysis showed that high T2 rSI value and marked contrast enhancement were independent predictors of the 2 subtypes, and the odds ratios were 4.811 and 4.649, respectively. The multivariate logistic model obtained relatively high predicting efficacy, and the area under the curve, sensitivity, and specificity were 0.765, 0.882, and 0.500, respectively. There are significant differences in tumor size, T2 signal intensity, T2 rSI, enhancement degree, and invasiveness between DG and SG adenomas. The logistic model based on the marked contrast enhancement and high T2 rSI value has an important value in predicting the subtype of growth hormone adenoma.

Mode coupling internal resonance characteristics of submerged floating tunnel tether

This study presents the mode coupling internal resonance characteristics of submerged floating tunnel tether. In which, in-plane and out-of-plane coupling of tether is taken into account. And the coupled vibration equations of tether for the in-plane first mode and out-of-plane first mode are obtained. The one-to-one mode coupling internal resonance characteristics of submerged floating tunnel tether are studied by numerical analysis method. It is shown that, when the conditions of modal coupling internal resonance are met, with the increase of the external excitation amplitude of the tether, the mid-span displacement of the tether increases gradually. When the amplitude of external excitation is less than a certain value, the internal resonance of tether will not occur. With the increase of damping ratio, the mid-span displacement of the tether decreases gradually. When the damping ratio increases to a certain value, the internal resonance will not occur. The study is helpful to restrain the vibration of submerged floating tunnel tether.

Resonance analysis using a high frequency simulation method for dc-SQUID amplifiers

We performed high-frequency simulation to optimize the geometric size of dc-SQUID amplifiers and to remove their intrinsic resonance characteristics from the operating range. The aim is to eliminate distortions in the IVΦ characteristics that ensures low noise and stable operation over a large range of bias current. With this method, we designed and fabricated a dc-SQUID amplifier with two series-connected octagonal loops to achieve a robust operating performance. The measured results not only show smooth IVΦ characteristics without any distortion, but also demonstrate that the swing voltage is much larger than the corresponding voltage realized without this method at the same bias current. In addition, the white flux noise level as low as 1.7 μΦ0/√Hz was achieved at 0.1 K corresponding to a low current noise level of 15 pA/√Hz.

OVERTON-RESONANT SINGING BASIS OF COMPOSITOR LANGUAGE (OVERTONE-RESONANT BASIS OF COMPOSITOR LANGUAGE)

The article substantiates the embodiment of the traditional overtone intonational song beginning in the composer’s work. The application of the main acoustic features of an authentic timbre is described, such as compression, the presence of «specific resonances», reliance on the vocal position and inharmonic overtones. The main composer’s task is to create a piece of music that would imitate or reproduce the resonance characteristic of the folk singing tradition — the overtone. The research is based on the method of sound-acoustic measurement of an audio signal. The work was performed using the Reaper V4,581 audio editor software (Digital Audio Workstation) and a spectrograph built into the Reaper brand iZotop Ozon5 Advansed. This model of the spectrograph allows you to see the spectrogram of the investigated audio material in 3D format and color image, which more accurately reflects the measurements of the vibration frequency of the sound wave, and is also equipped with a broadband FFT analyzer. The scientific novelty of the research lies in the consideration of composer folklorism from the point of view of the timbre acoustic model of authentic singing, and the adaptation of expressive means is investigated not within the framework of the style and manner of the melodic presentation of the material of individual composers, but from the point of view of the timbre content of the folklore voice. The article shows how the influence of ethno-singing on composer’s creativity is revealed through the prism of authentic timbre and the given spectral examples.

Design evaluation of microwave transmission properties of YBa2Cu3O7-based kinetic inductance detectors

We designed, fabricated, and characterized microwave transmission properties with rewound strip structures for YBa2Cu3O7 (YBCO)-based kinetic inductance detectors (KIDs). The superconducting rewound strip serves as a microwave resonator and as a broadband terahertz-wave antenna. To predict the microwave resonance characteristics before fabrication, the line-width (w) and space (s) dependence of the spiral resonators were analyzed using an electromagnetic simulator; the resonance frequency increased, and the quality factor decreased with increasing w and s from 10 to 40 μm. YBCO-based KID arrays with different w (10 and 40 μm) were fabricated on 10 mm-square MgO substrates, cooled to 3 K using a 4He refrigerator, and evaluated using a vector network analyzer to verify the result of the simulation experimentally. The measured resonance frequency ratio of 1.11 times (5.04 → 5.59 GHz) agreed with the simulated ones of 1.10 times (4.84 → 5.33 GHz) between w = 10 and 40 μm. The other resonance characteristics, such as transmission coefficient and quality factor, have a similar w dependence with the simulation.

Two-Dimensional Highly Sensitive Wireless Displacement Sensor With Bilayer Graphene-Based Frequency Selective Surface

In this paper, a two-dimensional wireless displacement sensor with high sensitivity composed of a bilayer graphene-based frequency selective surface (FSS) is proposed. The lengths of the strip-type resonators on the top and bottom layers of the FSS are different and perpendicular to each other. Based on the resonance and polarization characteristics of the FSS, two-dimensional displacement sensing can be realized. It is well validated both in simulation and experiment that the direction of the displacement can be distinguished by the variation trend of the resonant frequencies of the top and bottom layers. In experiment, the measured results of the FSS based wireless displacement sensor in the dynamic range of 5mm show high sensitivity of 280 MHz/mm in x direction and 370 MHz/mm in y direction. Moreover, the excellent mechanical and chemical stability of the multi-layer graphene also makes it suitable for harsh environments, showing good prospects in application.

Low Cost Multifunctional Planar RF Sensors for Dielectric Characterization and Quality Monitoring

Two planar resonant sensors for measuring permittivity and identifying adulteration in vegetable oils are presented in this paper. The sensors are designed to operate in 2.4 GHz Industrial, Scientific and Medical (ISM) band. The sensing technique is based on the change in resonance characteristics of the sensors with the variation in dielectric properties of the test sample in contact. The proposed sensors are capable of measuring the permittivity of solid as well as liquid samples. They can be easily immersed in liquids due to its single port topology and compactness. The prototypes of both the sensors are fabricated on FR4 epoxy substrate of thickness 1.6 mm. To experimentally validate their functionality, some of the commercially available dielectric materials are characterized using these fabricated sensors. The measured permittivity value of each sample showed a good match with the respective value available in the manufacturer’s data sheet. The use of solid test specimens in their commercially available thickness makes the test sample preparation simple and easier. Liquid dielectric characterization using these sensors is experimentally validated using some vegetable oil samples. Furthermore, different concentration levels of adulterant oil in pure vegetable oil are successfully detected by the proposed near field resonant sensors. The results demonstrate that the two sensors are capable for real time quality monitoring and permittivity measurement of solid and liquid materials.

A study on resonance characteristics of hydraulic structures and buildings conducted using small-size models

Introduction. The study focuses on resonance characteristics of a hydraulic engineering structure, such as a groin, land retention works on an artificial island, and a school building. Any structure, exposed to dynamic effects of natural or man-induced origin, can be validly simulated as a mechanical resonator. Models are made of materials that have electro-elastic properties allowing to measure responses to induced oscillations, or changes in an alternating electric field, and reevaluate the physical characteristics later.&#x0D; Materials and methods. Small-size physical models of structures are made of electro-elastic materials, such as organic glass and ABS plastic, used for 3D printing. A laboratory test bench, composed of an oscillator and a personal computer, used as an oscillograph, was applied to conduct the testing. Mathematical modeling was performed using SolidWorks software packages. Oscillation modes and structural responses, featuring different response amplitudes, were identified. Models of structures were studied in different contexts, including restraint and free bearing.&#x0D; Results. It has been found that frequencies of the first mode of oscillations in a restrained model correspond to the fourth mode of a model in case of free bearing. Mutual correlation of eigenfrequencies of oscillations in small-size models, made of ABS plastic and organic glass, is demonstrated.&#x0D; Conclusions. The applicability of ABS plastic as the material of small-size physical models of buildings and structures has been proven for the purpose of identifying resonance frequencies of the prototypes. The co-authors have developed an integrated physical and mathematical modeling method that entails the use of SolidWorks software packages. This method allows to identify resonance frequencies, which are most dangerous for structures. Different structure support patterns allow to apply the geometric scale to obtain resonance frequencies when translating small-size model results to natural values and, hence, identify the vulnerability of structures to dynamic effects.

Research on Novel CMUTs for Detecting Micro-Pressure with Ultra-High Sensitivity and Linearity.

Capacitive micromachined ultrasonic transducers (CMUTs) have been indispensable owing to their resonance characteristics in the MHz frequency range. However, the inferior pressure sensitivity and linearity of traditional CMUTs themselves cannot meet the actual demands of micro-pressure measurements. In this paper, two novel CMUTs are proposed for the first time to improve the measuring performance of micro-pressure in the range of 0–10 kPa. The core concept of the enhancement is strengthening membrane deformability by partly adjusting the CMUT framework under the combined action of electrostatic force and uniform pressure. Two modified structures of an inverted frustum cone-like cavity and slotted membrane are presented, respectively, and a finite element model (FEM) of CMUT was constructed and analyzed using COMSOL Multiphysics 5.5. The results demonstrate that the maximum displacement and pressure sensitivity are improved by 16.01% and 30.79% for the frustum cone-like cavity and 104.22% and 1861.31% for the slotted membrane, respectively. Furthermore, the results show that the width uniformity of the grooves does not influence the characteristics of the membrane, which mainly depend on the total width of the grooves, greatly enriching design flexibility. In brief, the proposed structural designs can significantly improve the micro-pressure measurement performance of the CMUT, which will accelerate the rapid breakthrough of technical barriers in the fields of aerospace, industry control, and other sensing domains.

Electromagnetic Properties of Carbon Nanotube/BaFe12-xGaxO19/Epoxy Composites with Random and Oriented Filler Distributions.

The microwave properties of epoxy composites filled with 30 wt.% of BaFe12–xGaxO19 (0.1 ≤ x ≤ 1.2) and with 1 wt.% of multi-walled carbon nanotubes (CNTs) were investigated in the frequency range 36–55 GHz. A sufficient increase in the microwave shielding efficiency was found for ternary 1 wt.%CNT/30 wt.% BaFe12–xGaxO19/epoxy composites compared with binary 1% CNT/epoxy and 30 wt.% BaFe12–xGaxO19/epoxy due to the complementary contributions of dielectric and magnetic losses. Thus, the addition of only 1 wt.% of CNTs along with 30 wt.% of barium hexaferrite into epoxy resin increased the frequency range where electromagnetic radiation is intensely attenuated. A correlation between the cation Ga3+ concentration in the BaFe12–xGaxO19 filler and amplitude–frequency characteristics of the natural ferromagnetic resonance (NFMR) in 1 wt.%CNT/30 wt.% BaFe12–xGaxO19/epoxy composites was determined. Higher values of the resonance frequency (51.8–52.4 GHz) and weaker dependence of on the Ga3+ concentration were observed compared with pressed polycrystalline BaFe12–xGaxO19 ( = 49.6–50.4 GHz). An increase in the NFMR amplitude on the applied magnetic field for both random and aligned 1 wt.% CNT/30 wt.% BaFe12–xGaxO19/epoxy composites was found. The frequency of NFMR was approximately constant in the range of the applied magnetic field, H = 0–5 kOe, for the random 1 wt.% CNT/30 wt.% BaFe12–xGaxO19/epoxy composite, and it slightly increased for the aligned 1 wt.% CNT/30 wt.% BaFe12–xGaxO19/epoxy composite.

Fabrication and Resonance Characteristics of PZT Cantilevers

Thin films of lead zirconate titanate Pb(Zr0,52Ti0,48)O3 (PZT) with thickness of 1.4 μm were prepared on Si/SiO2/TiO2/Pt substrates by chemical solutions deposition. Based on the obtained films, the structures of PZT cantilevers were formed, with a length from 500 to 1000 /um and wide from 100 to 500 μm. Platinum (100 nm) as the bottom and top electrode, has been deposited by magnetron sputtering. PZT cantilevers werereleased by etching the sacrificial layer in SF6. The resonance characteristics of the PZT cantilevers were determined by the light lever method using a special optical measuring stand. Output characteristics of the PZT cantilevers, can be used in MEMS devices, specially, in MEMS resonators.

Structural and magnetic studies of cobalt substituted magnetite ferrofluids

In this work, hydrocarbon based ferrofluids of cobalt substituted magnetite (Fe3O4) having the composition CoxFe3-xO4 (0.0≤x≤ 0.3 in steps of 0.1) were prepared using co-precipitation method, with oleic acid as the surfactant. The structural, microstructural and magnetic studies were carried out using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Field emission scanning electron microscope (FESEM), Vibrating sample magnetometer (VSM) and Electron spin resonance spectroscopy (ESR). It is aimed to investigate the role of incorporation of high anisotropy cobalt on the structural and magnetic properties of the basic system. The X-ray diffraction pattern and Rietveld refinement confirm the inverse spinel structure of magnetite with space group Fd-3 m. Residual lattice strain was estimated using Williamson-Hall plot. FESEM depicts the presence of spherical nanoparticles with average size 15 nm to 16 nm. Saturation magnetization values recorded using VSM was found to decrease with Co2+ substitution with negligible remanence and coercivity confirming the superparamagnetic behaviour of the ferrofluids. The peak-to-peak line width (ΔHpp), g-factor and the resonant magnetic field (Hr) were calculated from ESR measurement. The spin resonance characteristics reveal an increase in the ΔHpp and g-value and a decrease in Hr with increase of Co2+ content. Spin-lattice and spin–spin relaxation time were calculated and analysed to interpret the relaxation mechanism taking place in the ferrofluids. Based on the results of these characterizations and their analysis the investigated ferrofluids may find suitability as potential materials for hyperthermia application and radar absorbing materials respectively.

Sound Enhancement of Orthotropic Sound Radiation Plates Using Line Loads and Considering Resonance Characteristics

A new vibro-acoustic method is presented to analyze the sound radiation behavior of orthotropic panel-form sound radiators using strip-type exciters to exert line loads to the panels for sound radiation. The simple first-order shear deformation theory together with the Ritz method is used to formulate the proposed method that makes the vibro-acoustic analysis of elastically restrained stiffened orthotropic plates more computationally efficient than the methods formulated on the basis of the other shear deformation theories. An elastically restrained orthotropic plate consisting of two parallel strip-type exciters was tested to measure the experimental sound pressure level curve for validating the effectiveness and accuracy of the proposed method. The resonance characteristics (natural frequency and mode shape) detrimental to sound radiation are identified in the vibro-acoustic analysis of the orthotropic plate. For any orthotropic sound radiation plate, based on the detrimental mode shapes, a practical procedure is presented to design the line load locations on the plate to suppress the major sound pressure level dips for enhancing the smoothness of the plate sound pressure level curve. For illustration, the sound radiation enhancement of orthotropic plates with different fiber orientations for aspect ratios equal to 3, 2, and 1 subjected to one or two line loads is conducted using the proposed procedure. The results for the cases with two line loads perpendicular to the fiber direction and located at the nodal lines of the major detrimental mode shape may find applications in designing orthotropic panel-form speakers with relatively smooth sound pressure level curves.

Extremely Sensitive Microwave Microfluidic Dielectric Sensor Using a Transmission Line Loaded with Shunt LC Resonators

In this paper, a very high sensitivity microwave-based planar microfluidic sensor is presented. Sensitivity enhancement is achieved and described theoretically and experimentally by eliminating any extra parasitic capacitance not contributing to the sensing mechanism. The sensor consists of a microstrip transmission line loaded with a series connected shunt LC resonator. A microfluidic channel is attached to the area of the highest electric field concentration. The electric field distribution and, therefore, the resonance characteristics are modified by applying microfluidic dielectric samples to the sensing area. The sensor performance and working principle are described through a circuit model analysis. A device prototype is fabricated, and experimental measurements using water/ethanol and water/methanol solutions are presented for validation of the sensing mathematical model.

A novel cardiovascular magnetic resonance risk score for predicting mortality following surgical aortic valve replacement

The increasing prevalence of patients with aortic stenosis worldwide highlights a clinical need for improved and accurate prediction of clinical outcomes following surgery. We investigated patient demographic and cardiovascular magnetic resonance (CMR) characteristics to formulate a dedicated risk score estimating long-term survival following surgery. We recruited consecutive patients undergoing CMR with gadolinium administration prior to surgical aortic valve replacement from 2003 to 2016 in two UK centres. The outcome was overall mortality. A total of 250 patients were included (68 ± 12 years, male 185 (60%), with pre-operative mean aortic valve area 0.93 ± 0.32cm2, LVEF 62 ± 17%) and followed for 6.0 ± 3.3 years. Sixty-one deaths occurred, with 10-year mortality of 23.6%. Multivariable analysis showed that increasing age (HR 1.04, P = 0.005), use of antiplatelet therapy (HR 0.54, P = 0.027), presence of infarction or midwall late gadolinium enhancement (HR 1.52 and HR 2.14 respectively, combined P = 0.12), higher indexed left ventricular stroke volume (HR 0.98, P = 0.043) and higher left atrial ejection fraction (HR 0.98, P = 0.083) associated with mortality and developed a risk score with good discrimination. This is the first dedicated risk prediction score for patients with aortic stenosis undergoing surgical aortic valve replacement providing an individualised estimate for overall mortality. This model can help clinicians individualising medical and surgical care.Trial Registration ClinicalTrials.gov Identifier: NCT00930735 and ClinicalTrials.gov Identifier: NCT01755936.

Numerical Investigation of Shallow Liquid Sloshing in a Baffled Tank and the Associated Damping Effect by BM-MPS Method

Understanding the damping mechanism of baffles is helpful to make more reasonable use of them in suppressing liquid sloshing. In this study, the damping effect and mechanism of vertical baffles in shallow liquid sloshing under a rotational excitation are investigated by an improved particle method. By incorporation of a background mesh scheme and a modified pressure gradient model, the accuracy of impact pressure during sloshing is significantly enhanced. Combined with the advantages of the particle method, the present numerical method is a wonderful tool for the investigation of liquid sloshing issues. Through the analysis of impact pressure, the influences of baffle height and baffle position on the damping mechanism are discussed. The results show that the damping effect of vertical baffles increases with the increase of the elevation of baffle top and decreases with the increase of the elevation of the baffle bottom. Moreover, the resonance characteristics of sloshing are altered when static water is divided into two parts by the vertical baffle. The dominant damping mechanism of vertical baffles depends on the configurations.

Resonance Characteristics in Epiglottic Cyst: Formant Frequency, Vowel Space Area, Vowel Articulatory Index, and Formant Centralization Ratio

ObjectivesResonance characteristics can change due to alterations in the shape of the vocal tract in patients with epiglottic cysts. This study aimed to analyze the resonance characteristics before and after the surgical excision of epiglottic cysts. MethodsTwelve male patients with epiglottic cysts were enrolled in this study. We analyzed the first and second formants (F1 and F2) in vowels /a/, /e/, /i/, /o/, and /u/, vowel space area (VSA), vowel articulatory index (VAI), and formant centralization ratio (FCR). We measured these parameters before and after the surgical excision of epiglottic cysts. ResultsThere was a significant increase in the F1 values of /a/, VSA, and VAI, and a significant decrease in the value of FCR after the surgery. ConclusionWe confirmed the change in the resonance characteristics in patients with epiglottic cysts. It is considered that further studies on epiglottic cysts and resonance changes are needed in the future.

Bulk acoustic wave resonance characteristic modified by reducing the defects in ZnO-based solidly mounted resonators

The c-axis zinc oxide (ZnO) multi-layered films and ZnO-based solidly mounted resonators (SMR) based on high-resistivity silicon substrates have been fabricated by using the combination of sputtering and photolithography with the absence of oxygen and heating. Subsequent annealing procedure was performed to improve the quality of ZnO films and devices. The X-ray diffraction (XRD) measurements reveal that all ZnO films are well crystallized and highly textured, the grain size gradually increases from 18.2 to 20.5 nm with the increasing of annealing temperature (Tann). The X-ray photoelectron spectrometer (XPS) results indicate that the high concentration oxygen defects of as-deposited ZnO films can be reduced through increasing Tann. By comparing the measured electrical properties of the devices before and after various Tann annealing, it was found that the annealing treatment can be used to improve the resonance characteristics, the relative change in return loss (S11) increased from 0 to 0.72 dB and then decreased to 0.07 dB as Tann increases from room temperature to 700 °C. In addition, S11 relative change can also be enhanced from 0.29 to 0.67 by decreasing the effective working area of the devices from 100 × 160 μm2 to 100 × 50 μm2.

A new liquid sensor based on a piezoelectric resonator with a radial electric field

The possibility of development a liquid sensor based on a piezoelectric resonator with radial concentric electrodes is shown. The specified resonator has a large number of resonance peaks corresponding to different vibrational modes. The influence of two types of liquid container with distilled water on the resonance characteristics of these vibrational modes is experimentally investigated. As a result, the optimal type of container and two vibrational modes with frequencies of 0.128 and 0.317 MHz were selected, which retain acceptable Q-factors in the presence of distilled water. The dependences of the resonance frequency and the maximum value of the real part of the electrical impedance of these resonance peaks on the conductivity of the liquid were measured. It has been found that with an increase in the conductivity of the liquid, the resonance frequency of the parallel resonance initially remains practically unchanged, but after reaching a certain value of the conductivity of water, it decreases for both resonances. In this case, the maximum value of the real part of the electrical impedance first decreases, reaches a minimum, and then increases in all cases. It is shown that using these dependences as calibration curves, one can unambiguously determine the conductivity of a liquid in the range of 45–5000 μS/cm.