Resonance Frequency Values Research Articles

Infrared spectra, Raman spectra, microwave dielectric properties and simulation for effective permittivity of temperature stable ceramics AMoO4–TiO2(A = Ca, Sr)

In this work, temperature stable microwave dielectric materials (1 - x)AMoO(4)-xTiO(2) (A = Ca, Sr) were prepared by a solid state reaction method. The phase composition, sintering behaviors, microstructures, microwave dielectric properties, effective permittivity and vibrational phonon modes were investigated. The X-ray diffraction pattern and scanning electron microscope analysis indicated that the AMoO(4) (A = Ca, Sr) phase could coexist with the TiO(2) phase. The effective dielectric constants of the AMoO(4)-TiO(2) composites were calculated by the finite element method (FEM), compared with the measured values and the numerical results obtained by the classical mixing rules. The correlation between the dielectric properties and the crystal structures were studied using IR and Raman spectroscopy. The infrared spectra were analyzed using the classical harmonic oscillator model, and revealed that the external vibration modes of AMoO(4) (A = Ca, Sr) had the most significant influence on the dielectric constant. The Raman spectra showed that there were strong interactions in the [MoO(4)] tetrahedron due to the sharp and intense Raman modes. Finally, the low-firing (900 °C) microwave dielectric ceramics were obtained with 3 wt% H(3)BO(3)-CuO addition (BCu), and they possess good microwave dielectric properties with ε(r) = 10.6-13, high Q×f values (40 700-72 050 GHz), and near-zero temperature coefficients of resonant frequency (TCF or τ(f) values). These results also show that (1 - x)AMoO(4)-xTiO(2)-BCu (A = Ca, Sr) ceramics are good candidates for microwave electronic device applications.

Measurement and Simulation Techniques for Piezoresistive Microcantilever Biosensor Applications

Applications of microcantilevers as biosensors have been explored by many researchers for the applications in medicine, biological, chemistry, and environmental monitoring. This research discusses a design of measurement method and simuations for piezoresistive microcantilever as a biosensor, which consist of designing Wheatstone bridge circuit as object detector, simulation of resonance frequency shift based on Euler Bernoulli Beam equation, and microcantilever vibration simulation using COMSOL Multiphysics 3.5. The piezoresistive microcantilever used here is Seiko Instrument Technology (Japan) product with length of 110 ?m, width of 50 ?m, and thickness of 1 ?m. Microcantilever mass is 12.815 ng, including the mass receptor. The sample object in this research is bacteria EColi. One bacteria mass is assumed to 0.3 pg. Simulation results show that the mass of one bacterium will cause the deflection of 0,03053 nm and resonance frequency value of 118,90 kHz. Moreover, four bacterium will cause the deflection of 0,03054 nm and resonance frequency value of 118,68 kHz. These datas indicate that the increasing of the bacteria mass increases the deflection value and reduces the value of resonance frequency.

Abnormal variation of microwave dielectric properties in A/B site co-substituted (Ca1−0.3xLa0.2x)[(Mg1/3Ta2/3)1−xTix]O3 complex perovskite ceramics

Abstract A/B site co-substituted (Ca1−0.3xLa0.2x)[(Mg1/3Ta2/3)1−xTix]O3 ceramics (0.1 ≤ x ≤ 0.5) were prepared by solid state reaction and the structures, microstructures and dielectric properties were investigated. B site 1:2 cation ordering and oxygen octahedra tilting lead to monoclinic symmetry with space group P21/c for x = 0.1. For x above 0.1, the ordering was destroyed and the crystal structure became orthorhombic with space group Pbnm. The B site 1:2 cation ordering tended to be destroyed to form 1:1 ordering by the A site La3+ substitution. The dielectric constant increased linearly with increasing content of Ti4+ as the increasing second Jahn–Teller distortion enhanced the B site cation rattling. The temperature coefficient of resonant frequency and Qf values showed abnormal variations, which were refined to be caused by the increasing A site cation vacancy and diffused distribution of small size ordering domains respectively. Good combination of microwave dielectric properties was obtained at x = 0.5, where ɛr = 48, Qf = 21,000 GHz and τf = 2.2 ppm/°C.

Microstructures and microwave dielectric properties of Ba4LiNb3O12–BaWO4 composite ceramics

Abstract Composite ceramics of (1 − x)Ba4LiNb3O12–xBaWO4 (x = 0.36–0.69) had been synthesized by co-firing the mixtures of Ba4LiNb3O12 and BaWO4 powders. The structures and microwave dielectric properties of the ceramics were studied by XRD, SEM, and TEM. These ceramics consisted of hexagonal Ba4LiNb3O12 and tetragonal BaWO4. The two phases co-existed well in the ceramics, and there was not obvious reaction at interfacial areas among grains. These ceramics had low sintering temperatures and excellent microwave dielectric properties, especially the small temperature coefficients of resonant frequency (τf) and high quality factor (Q × f) values. For composition at x = 0.69, the ceramic sintered at 1070 °C had Q × f value of 75,500 GHz and τf value of +8.7 ppm/°C.

Studies on Site Specific Responses and its relationship with the Geological Formations in Kochi City of Kerala State, India

The site response studies have been undertaken by measuring records of ambient noise vibrations in Kochi city of Kerala state, India with the objective of defining the site effects as this forms the most important input associated with the local geological conditions and constitute an important part of any seismic hazard assessment and microzonation map. The resonance frequency and the ground motion amplification thus estimated show very interesting features in their spatial variability and have specific range of resonance frequency associated with different geological formations from soft soils to compact rocky sites. The results suggest that the resonance frequency varies significantly within short distances in and around Kochi city. The detailed seismic microzonation map prepared for Kochi city contains five classes of resonance frequency ( 10 Hz) and three classes of site amplification ( 10.0). The resonance frequency is spatially distributed in three NW-SE trending segments parallel to the coast which differ appreciably in their site response characteristics. The lowest resonance frequency values (≤ 1.0 Hz) coupled with generally high site amplification were observed in coastal and backwater areas covered with younger alluvial deposits, and high resonance frequency values (> 5 Hz) to charnockites and laterites in the hinterlands. It is demonstrated that site specific natural frequency can be used very successfully to delineate geological formations in a region provided closely spaced ambient noise data are available.

Influence of different implant materials on the primary stability of orthodontic mini-implants

This study evaluates the influence of different implant materials on the primary stability of orthodontic mini-implants by measuring the resonance frequency. Twenty-five orthodontic mini-implants with a diameter of 2 mm were used. The first group contained stainless steel mini-implants with two different lengths (10 and 12 mm). The second group included titanium alloy mini-implants with two different lengths (10 and 12 mm) and stainless steel mini-implants 10 mm in length. The mini-implants were inserted into artificial bones with a 2-mm-thick cortical layer and 40 or 20 lb/ft3 trabecular bone density at insertion depths of 2, 4, and 6 mm. The resonance frequency of the mini-implants in the artificial bone was detected with the Implomates® device. Data were analyzed by two-way analysis of variance followed by the Tukey honestly significant difference test (α = 0.05). Greater insertion depth resulted in higher resonance frequency, whereas longer mini-implants showed lower resonance frequency values. However, resonance frequency was not influenced by the implant materials titanium alloy or stainless steel. Therefore, the primary stability of a mini-implant is influenced by insertion depth and not by implant material. Insertion depth is extremely important for primary implant stability and is critical for treatment success.

Analysis, manufacture and characterization of Ni/Cu functionally graded structures

In this work, an experimental and numerical analysis and characterization of functionally graded structures (FGSs) is developed. Nickel (Ni) and copper (Cu) materials are used as basic materials in the numerical modeling and experimental characterization. For modeling, a MATLAB finite element code is developed, which allows simulation of harmonic and modal analysis considering the graded finite element formulation. For experimental characterization, Ni–Cu FGSs are manufactured by using spark plasma sintering technique. Hardness and Young’s modulus are found by using microindentation and ultrasonic measurements, respectively. The effective gradation of Ni/Cu FGS is addressed by means of optical microscopy, energy dispersive spectrometry, scanning electron microscopy and hardness testing. For the purpose of comparing modeling and experimental results, the hardness curve, along the gradation direction, is used for identifying the gradation profile; accordingly, the experimental hardness curve is used for approximating the Young’s modulus variation and the graded finite element modeling is used for verification. For the first two resonance frequency values, a difference smaller than 1% between simulated and experimental results is obtained.

High frequency characteristics of FeCoAlO thin films fabricated with asymmetric target at different Ar gas flow rates

FeCoAlO thin films with good soft magnetic properties were fabricated by using RF magnetron sputtering. In order to obtain good high-frequency performance, the in-plane uniaxial anisotropy was tuned by combining the effects of in situ magnetic field and the gradient of Al–O concentration. The composition gradient was controlled by using an asymmetric target and different Ar gas flow rates changing from 5 sccm to 17.5 sccm. It was found that at the range of Ar gas flow rate from 7.5 sccm to 15 sccm, the films showed an excellent high-frequency performance: the resonance frequency was beyond 3.0 GHz and the real permeability μ′ had a high value of ∼200 at low-frequency side. In particular, the film prepared at the Ar gas flow rate of 15 sccm showed a resonance frequency of 4.0 GHz. Large resonance frequency can be attributed to the high in-plane uniaxial anisotropy field which was induced by stress and the external magnetic field. The high values of permeability and resonance frequency enable the FeCoAlO thin films to be one of the important candidates for microwave applications.

Microwave dielectric properties of (1 − x)Ca0.6La0.267TiO3 − xCa(Sm0.5Nb0.5)O3 ceramics

Microstructures and microwave dielectric properties of (1−x)Ca0.6La0.267TiO3−xCa(Sm0.5Nb0.5)O3 (0.1≤x≤0.7) ceramics have been investigated. A two-phase system was formed in the given compositional range. The grain morphology exhibited two different types of grain: large circular grain and small square grain. With the increasing x value, the grain morphology of the small square grain became irregular. The microwave dielectric properties were strongly related to the composition. As the x value increased from 0.1 to 0.7, the dielectric constant (ɛr) decreased from 87 to 48.3, the quality factor (Q×f) value from 14390 to 8360GHz, and the temperature coefficient of resonant frequency (τf) value from +130.6 to −24.8ppm/°C, respectively. For practical application, an ɛr of 74.3, a Q×f value of 12690GHz and a τf value of +8.8ppm/°C were obtained for 0.7Ca0.6La0.267TiO3−0.3Ca(Sm0.5Nb0.5)O3 ceramics sintered at 1450°C for 4h.

Crystal structure and microwave dielectric properties of low temperature sintered MgO ceramic with LiF addition

Abstract

A finite element analysis of the vibration behaviour of a cementless hip system

An early diagnosis of aseptic loosening of a total hip replacement (THR) by plain radiography, scintigraphy or arthography has been shown to be less reliable than using a vibration technique. However, it has been suggested that it may be possible to distinguish between a secure and a loose prosthesis using a vibration technique. In fact, vibration analysis methods have been successfully used to assess dental implant stability, to monitor fracture healing and to measure bone mechanical properties. Several studies have combined the vibration technique with the finite element (FE) method in order to better understand the events involved in the experimental technique. In the present study, the main goal is to simulate the change in the resonance frequency during the osseointegration process of a cementless THR (Zweymüller). The FE method was used and a numerical modal analysis was conducted to obtain the natural frequencies and mode shapes under vibration. The effects were studied of different bone and stem material properties, and different contact conditions at the bone–implant interface. The results were in agreement with previous experimental and computational observations, and differences among the different cases studied were detected. As the osseointegration process at the bone–implant interface evolved, the resonance frequency values of the femur–prosthesis system also increased. In summary, vibration analysis combined with the FE method was able to detect different boundary conditions at the bone–implant interface in cases of both osseointegration and loosening.

Microstructure and microwave dielectric properties of (1 − x)Ca0.6La0.267TiO3–xCa(Mg1/3Nb2/3)O3 ceramics

(1−x)Ca0.6La0.267TiO3–xCa(Mg1/3Nb2/3)O3 ceramics were prepared by a conventional solid-state ceramic route. The microstructure and microwave dielectric properties were investigated as a function of composition and sintering temperature. As the content of Ca(Mg1/3Nb2/3)O3 increased, the temperature coefficient of resonant frequency (τf) value decreased gradually. By appropriately adjusting the x value in the present ceramic system, a near-zero τf value could be achieved. The appropriate increase of sintering temperature could significantly improve Q·f value by influencing the grain growth. The optimal microwave dielectric properties with a dielectric constant (ɛr) of 52.4, Q·f of 36,428GHz (at 5.8GHz), and τf of 3.4ppm/°C were obtained for the specimen 0.5Ca0.6La0.267TiO3–0.5Ca(Mg1/3Nb2/3)O3 sintered at 1490°C for 4h.

127 複合素材ヤリの特性(スポーツ用具・材料)

In this study, the characteristics of the men's javelin were investigated in terms of its material in order to collect basic data about the required properties of the javelin. Made of various materials (composite materials: 7; steel: 5; duralumin: 8), 20 types of javelins were examined to assess the static characteristics of shape, center of gravity, and moment of inertia, as well as the characteristics of vibration and static bending stiffness. The properties of the composite javelins were clarified, and the effects of javelin material in a javelin throw competition are discussed. Although all the javelins had the same shape, for the composite javelins, wide scatter was observed in the values of the primary resonant frequency, the moment of inertia around the center of gravity, and the compliance at the position of the loop. Therefore, the composite javelins have a pattern of various mass distributions. Further, the composite javelins were stiffer than the steel and duralumin javelins, and exhibited the characteristic that their vibration was easy to damp.

Structural dependence of microwave dielectric properties of ixiolite structured ZnTiNb2O8 materials: crystal structure refinement and Raman spectra study

Structural and property relationships of ixiolite structured ZnTiNb(2)O(8) microwave dielectric materials were studied by structure refinement and Raman spectra analysis. The vibration modes which have Raman activities of the ixiolite structure were assigned for the first time. The bands with wavenumbers greater than 450 cm(-1) can be associated with several modes (A(g(2)), B(3g(1)), B(3g(2)), A(g(1)), B(1g(2)), A(g(3)), B(2g(2))) involving the stretching of the cation-O bonds. For wavenumbers between 250 and 450 cm(-1), the bands are due, principally, to the bending of O-cation-O (B(1g(1)), B(2g(1)), B(1g(3))). The origin of the bands with wavenumbers below 250 cm(-1) would be lattice vibrations (B(1g(4)), A(g(4)), B(3g(4)), B(2g(4))), mainly associated with cation ions. The correlation between bond strength and packing fraction, Raman shift, full width at half maximum (FWHM) of Raman spectra were discussed. With increase of bond strength, the oxygen octahedron became rigid, the Raman shift increased, and the damping behavior became weaker. With increase of Raman shift, the dielectric constant decreased. With increase of packing fraction and decrease of FWHM, the Q(f) (quality factor × resonance frequency) value increased. The τ(f) (temperature coefficient of resonance frequency) decreased with increase of bond strength. And there was no direct relationship between oxygen octahedron distortion and τ(f). The excellent microwave dielectric properties of ZnTiNb(2)O(8) in this work were: dielectric constant (ε) = 34.4, Q(f) = 56,900 GHz, τ(f) = -47.94 × 10(-6)/°C.

Resonant properties of sessile droplets; contact angle dependence of the resonant frequency and width in glycerol/water mixtures

A simple optical deflection technique was used to monitor the vibrations of small (microlitre) sessile droplets of glycerol/water mixtures when a puff of air was used to apply an impulse to the drops. A photodiode was used to detect time dependent variations in the intensity of laser light that was reflected from the droplets. The intensity variations obtained from droplets with masses in the range 0.0005–0.03 g were Fourier transformed to obtain information about the resonant properties (frequency and width of the resonance). These experiments were performed on a range of different substrates where the three phase contact angle formed by the droplets varied between 38 ± 2° and 160 ± 4°. This was repeated for droplets with glycerol compositions ranging from 10% to 75%. The measured resonant frequency values were found to be in good agreement with a recently developed 1-D theory of vibrations in sessile droplets which considers standing wave states around the meridonal profile length of the droplet. The widths of the resonances were also compared with modified theories which predict the influence of substrate effects, surface contamination effects and bulk viscous effects on the damping of capillary waves at the free surface of the droplets. These experiments indicate that the dominant source of damping in sessile liquid droplet is due to bulk viscous effects but that for small contact angles damping due to the droplet/substrate interaction becomes more important.

Dielectric properties and crystal structure of Mg 2TiO 4 ceramics substituting Mg 2+ with Zn 2+ and Co 2+

Solid solutions of [(Mg, Zn)] 2TiO 4–Co 2TiO 4 were used to prepare [(Mg 1− x Zn x ) 0.95Co 0.05] 2TiO 4 have been fabricated using solid-state synthesis for mobile communications. The effect of Zn 2+ and Co 2+ substitution were to enhance Q × f value and densification sintering at lower temperature compared to Mg 2TiO 4 which sintered at 1450 °C. As an optimal compose, [(Mg 0.5Zn 0.5) 0.95Co 0.05] 2TiO 4 successfully demonstrated a dielectric constant of 18.18, a Q × f of 206,000 GHz and a τ f value of −20.8 ppm/°C sintered at 1225 °C. The maximum quality factor multiples resonant frequency ( Q × f) value of around 2100,000 GHz was obtained for the [(Mg 0.6Zn 0.4) 0.95Co 0.05] 2TiO 4, and added more Zn 2+, the Q × f decrease [(Mg 0.5Zn 0.5) 0.95Co 0.05] 2TiO 4.

Design and Simulation of RF MEMS Tunable Spiral Inductor

This paper presents a tunable inductor using MEMS technology .This tunable spiral inductor is designed in order to be used in RF circuits such as : controlled oscillators with voltage (VCO) , matching networks ,amplifiers etc . The electrostatic method is employed for tuning the inductor by the movement of cantilever beam downward and changing the value of magnetic flux. Value of inductance varies fram 1.15nh to 0.561 nh .therefore ,tunablity of 66.21% was achieved .Maximum quality factor in the above inductor was achieved az 13.88 in the frequency 0f 12 GHz and the value of resonance frequency was achieved as 19.5 GHz

Microstructure and thickness dependent magnetic properties of nanogranular Co–Zn–O thin films for microwave applications

Co-based granular thin films with in-plane anisotropy were deposited on Si substrate by magnetron sputtering. The films have a phase structure of Co nanocrystallites and amorphous Zn–O inter-granular phases. The Co nanograins with uniform size of 8–10 nm are evenly distributed in the amorphous matrix. This structure gives the films relatively high resistivities. The as-deposited films with thickness larger than 100 nm have low coercivity (<10 Oe) along both easy and hard directions. The dynamic properties in the frequency range up 5 GHz for the films with various thicknesses have been investigated. High values of permeability ( μ′ up to 560 and μ″ up to 1000) and ferromagnetic resonance frequency (FMR) up to 4.1 GHz have been obtained in these films. The FMR frequency decreases with increasing thickness, because of the increases in real and imaginary permeabilities. The high frequency characteristics have complicated dependences on the resistivity, anisotropy field, and magnetization. The microwave properties of Co–Zn–O films can be adjusted in a relatively wide range by changing film thickness, which makes these films promising for absorber applications.

THE THEORETICAL ASPECTS OF MODELLING AND DESIGNING OF RESONATOR PROBES FOR SCANNING MICROWAVE MICROSCOPY

In the work the general approaches to an estimation of influence of characteristics resonator probes on spatial resolution and contrast of images in scanning microwave microscopy are proved. In particular, the dependences of scanning signals which are caused by influence of object of research on a value of quality factor and resonance frequency of probes from geometry of the coaxial aperture, the form of an edge and gap size between a probe and object are qualitatively and quantitatively established. For a physical substantiation of these dependences on the specified characteristics there were three dimensional distributions of a near field numerically investigated. Transition from «tubular» character of distribution of a field, which is characteristic for the flat form of an edge, to quasigaussian distribution of a field for the spherical form of an edge is especially pointed.The established dependences can be used for optimum designing of resonator probes of microwave microscopes for different function.

Structural Analysis of Cyclic-loaded Nickel-Titanium Rotary Instruments by Using Resonance Frequency as a Parameter

Introduction The aim of this study was to investigate the relationship between fatigue life and resonance frequency (RF) of various types of nickel-titanium (NiTi) rotary instruments. In addition, the influence of NiTi instruments with different manufacturing methods on cyclic loading was evaluated by using RF as a parameter. Methods Twenty-eight ProFile instruments and 10 Twisted File instruments were subjected to cyclic fatigue-loading until fracture by repeated preparation with simulated root canals made of clear resin. The RF of each sample was recorded immediately after the simulated canal block was prepared. For each sample, the microscopic images on the fracture surface, change in lengthening deformation, number of canal blocks prepared, and corresponding RF changes were recorded. Results For all the tested instruments, RF values decreased gradually before breakdown when the fatigue failure of the instruments was associated with plastic deformation. In addition, there was a linear relationship between the RF change and the corresponding deformation of the failed instruments. Conclusions These results demonstrate that the RF analysis has potential as a tool for structural analysis in NiTi instruments.