Double-resonance quartz crystal oscillator and excitation of a resonator immersed in liquid media

In this work we propose a novel circuit design: a double-resonance oscillator. Its oscillation shows two oscillation modes: frequency locking to the quartz crystal resonance and LC resonance oscillation. Transition of the oscillation mode and the strength of oscillation are analyzed and reviewed for the fundamental mode in comparison with a Colpitts oscillator. The experimental results support the estimates of negative resistance for the double-resonance oscillator compared with the LC oscillator.     

Resonance shifts of transverse-electric whispering gallery modes in a spheroidal resonator

A variational method was applied to find the wave function of a transverse-electric whispering gallery mode (WGM) in a spheroidal resonator of a uniform refractive index (RI). It was found that the electric field is tangential to the resonator surface as in the sphere, up to the linear order of the ellipticity. Using the wave function, the resonance shift due to adsorption of a thin, uniform dielectric layer onto the surface and the shift by a uniform RI change in the surroundings were evaluated in the perturbation theory. The shift by the RI change is not affected by the ellipticity, but the shift by the layer adsorption now depends on the meridional order. However, the correction is not large unless the ellipticity is large and the meridional order is away from the one for the equatorial mode of WGM.     

The electro-structural behaviour of yarn-like carbon nanotube fibres immersed in organic liquids

Yarn-like carbon nanotube (CNT) fibres are a hierarchically-structured material with a variety of promising applications such as high performance composites, sensors and actuators, smart textiles, and energy storage and transmission. However, in order to fully realize these possibilities, a more detailed understanding of their interactions with the environment is required. In this work, we describe a simplified representation of the hierarchical structure of the fibres from which several mathematical models are constructed to explain electro-structural interactions of fibres with organic liquids. A balance between the elastic and surface energies of the CNT bundle network in different media allows the determination of the maximum lengths that open junctions can sustain before collapsing to minimize the surface energy. This characteristic length correlates well with the increase of fibre resistance upon immersion in organic liquids. We also study the effect of charge accumulation in open interbundle junctions and derive expressions to describe experimental data on the non-ohmic electrical behaviour of fibres immersed in polar liquids. Our analyses suggest that the non-ohmic behaviour is caused by progressively shorter junctions collapsing as the voltage is increased. Since our models are not based on any property unique to carbon nanotubes, they should also be useful to describe other hierarchical structures.     

Resonance shift induced by free carriers of a silicon resonator of quadrangular shape

The nonlinear optical interaction of a silicon resonator with a quadrangular shaped smooth bend is studied with inclusion of free carriers (FCs), two-photon absorption, the Kerr effect, and loss. It is shown that for the range of input light power from zero up to 2 W, the incident light transmits between the silicon resonator and waveguide linearly. However, with an increase of light power from 2 W to higher values, the light transmission decreases very rapidly, so that it approximately vanishes at about 10 W. Furthermore, the resonance spectrum and stability condition of the silicon resonator in the nonlinear regime is studied with inclusion of FC dispersion and FC absorption for continuous wave operation. Thermal effects induced by FC absorption increase the refractive index, which causes a redshift of about 1.2 nm for 125.13 mW light power.     

Dielectric constant measurement of low loss liquids using stacked multi ring resonator

The concept of dielectric constant measurement has been extended and applied in agriculture, pharmaceutical and food industry for quality control of liquids. Dielectric analysis of material at microwave frequencies can be done using novel shielded stacked multi-ring resonator (SMRR). The dielectric constant of liquids and paste has been calculated using SMRR with greater accuracy than the planar resonator, boxed resonator and stacked resonator. SMRR contains a ring resonator with fed patch and parasitic patch with different numbers and sizes of rings. The dimensions of rings on the parasitic patch are optimized to achieve Quality factor Q greater than 100 and return loss less than ?2 dB. Due to dual resonance in novel SMRR, structure losses are reduced by 50% than planar resonator structure. The behavior of SMRR structure at the 2.45 GHz frequency is studied with E field and H field. 3D model is designed in Computer Simulation Technology Microwave Studio (CST MWS) using TLM (Transmission Line Modeling) solver. Electromagnetic field analysis as well as impedance bandwidth of SMRR using CST MWS 3D model prove that electromagnetic coupling in SMRR structure increases thus improves quality factor. In SMRR quality factor increases and losses reduce help us to predict the complex permittivity of material for quality analysis.     

Resonance asymmetry induced bias errors in waveguide type optical passive resonator gyro

We present an in-depth analysis of the resonance asymmetry in a silica waveguide ring resonator (WRR) and its influence on the waveguide-type optical passive resonator gyro (OPRG). A big bias error appears at the output of the OPRG. This big error is caused not only by the resonance asymmetry in the WRR, but also by the modulation parameters in the phase modulation spectroscopy technique (PMST). It has been proved that the bias error is proportional to the modulation frequency difference between the clockwise (CW) and counterclockwise (CCW) lightwaves. Three types of resonance asymmetries are thoroughly introduced and discussed. Methods to overcome the big bias error are demonstrated. A high reciprocal resonator is crucial to reduce the bias error. For a certain resonator, a proper temperature needs to be set to minimize the resonance asymmetry. A proper modulation frequency difference between the CW and CCW lightwaves is also helpful to reduce the bias error.     

Nanocomposite microfiber spinning using a UV-curable polymer in an aqueous environment

We report a hydrodynamic assisted nanocomposite microfiber spinning method using a UV-curable polymer. In contrast to a large number of previously reported fiber spinning methods, all the fabrication processes in the present method are performed in an aqueous environment, based on a photopolymerization process. The diameter of the spun fiber can be easily controlled at the scale of hundred microns by varying the draw ratio (the ratio of the take-up speed to the extrusion speed). To characterize the hydrodynamic phenomenon of polymer drawing, an analytic model and relevant physical parameters are employed. We also demonstrate QD (quantum dot)-based RGB color-emitting nanocomposite fibers and hetero-structural nanocomposite fibers with an RGB color column showing a rotational symmetry of 120° in one-step fabrication. Our approach is straightforward to implement using a variety of UV-curable polymers and can be applied to fabricate nanocomposite fibers with various physical properties and geometries. The processing features enable diverse possibilities for preparing novel nanocomposite materials and expanding the potential application of spun fibers.     

Combustion of a fuel drop immersed in a hot atmosphere

The combustion of a liquid fuel drop immersed in a hot atmosphere is considered when the activation energy is very large. Closed form solutions are obtained which describe a monotone variation of burning rate with Damkohler number, $\text{d}{}_1$. For some of the solutions the burning rate varies from the frozen limit at $\text{d}{}_1\text{= 0}$, to the Burke-Schumann limit at $\text{D}{}_1\text{= α}$. For all the others the burning rate varies from the frozen limit to a large $\text{D}{}_1$ limit distinct from the Burke-Schumann limit.     

Fundamental studies of liquid chromatography at the critical condition using enhanced-fluidity liquids

The improvement in the analysis of telechelic polymer matrixes continues to be a pursuit for many scientists of varying disciplines. This quest for a new technique has led to the continued development of liquid chromatography at the critical condition (LCCC) or liquid chromatography at the critical adsorption point (LC-CAP). LCCC allows for the isolation of one area of the polymer matrix so that other areas of the polymer can be probed with size-exclusion or adsorptive chromatographic modes. Although this technique has been successfully applied to the analysis of telechelic polymers, the practice of LCCC can be difficult. These difficulties include finding and maintaining a solvent system appropriate for the practice of LCCC as well as deterioration of peak shape once the system is operating at the LCCC mode. Because of the specificity of the mobile phase required for the practice of LCCC, the work is routinely practiced by premixing solvents. Previous work with enhanced-fluidity liquid mobile phases demonstrated that these mobile phases removed many of the aforementioned challenges associated with working at the LCCC mode. These mobile phases utilize both pressure and temperature variation in order to maintain the specific solvent strength necessary for the LCCC work. This work studies the coupling and optimization of enhanced-fluidity, EF, liquid mobile phases for LCCC. Several EF-LCCC systems, differing in mobile phase composition, temperature, and pressure, were routinely established, resulting in the effective practice of critical chromatography. The practice of LCCC with on-line mobile phase preparation is demonstrated using commercially available instrumentation. Finally, EF-LCCC is used to analyze triblock and diblock copolymers.     

Coupled analysis on the thickness-shear vibrations of a quartz plate resonator covered with micro-beams immersed in inviscid liquid and computation of the induced frequency-shift by the surface loadings

The dynamic equations of a quartz crystal resonator (QCR) vibrating in the thickness-shear modes (TSM) with the upper surface covered by an array of micro-beams, while the micro-beams are immersed in inviscid liquid, is established. A frequency-dependent effective mass ratio is put forward to simulate the effect of surface loadings (micro-beams immersed in liquid) on the dynamic characteristics of QCR. The seeping depth of vibration energy into liquid is analyzed and the added mass of liquid to micro-beams is examined. The induced frequency-shift of the compound QCR system consisting of QCR and the surface loadings is calculated in detail.     

差分振子检测器输出特性研究及应用

差分振子是一种周期信号检测方法,但在强噪声干扰下其相图会变模糊。为了解决这一问题,通过差分振子的数学模型求得了差分振子相图收敛时间与参数 的关系,利用该关系绘制出改进的差分振子相图,弥补了强噪声背景差分振子相图模糊不清的缺憾,同时给出了改进的差分振子系统参数的设置原则。理论分析、数值仿真及实验验证均表明该方法相比传统差分振子检测方法能取得更好的效果,可实现机电设备早期故障可视化检测。     

Formation of a gas bubble on a vibrating capillary immersed in a liquid

The formation of a train of bubbles in a low-viscosity liquid is investigated. The dependence of the gas flow rate during formation of the bubble train on the vibrational acceleration of the capillary is determined.Deceased.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 30, No. 4, pp. 665–670, April, 1976.     

Hysteresis in a carbon nanotube based electroactive polymer microfiber actuator: numerical modeling

Hysteretic behavior is an important consideration for smart electroactive polymer actuators in a wide variety of nano/micro-scale applications. We prepared an electroactive polymer actuator in the form of a microfiber, based on single-wall carbon nanotubes and polyaniline, and investigated the hysteretic characteristics of the actuator under electrical potential switching in a basic electrolyte solution. For actuation experiments, we measured the variation of the length of the carbon-nanotube-based electroactive polymer actuator, using an Aurora Scientific Inc. 300B Series muscle lever arm system, while electrical potentials ranging from 0.2 V to 0.65 V were applied. Based on the classical Preisach hysteresis model, we presented and validated a numerical model that described the hysteretic behavior of the carbon-nanotube-based electroactive polymer actuator. Inverse hysteretic behavior was also simulated using the model to demonstrate its capability to predict an input from a desired output. This numerical model of hysteresis could be an effective approach to micro-scale control of carbon-nanotube-based electroactive polymer actuators in potential applications.     

Calculation of the nonstationary temperature of a body immersed in a dispersed medium

The problem of the nonstationary temperature of bodies immersed in a dispersed medium is investigated.     

Broadband absorbance in a liquid-core optical ring resonator

We have demonstrated the application of broadband absorption spectroscopy in a liquid-core optical ring resonator. An initial proof of concept of the broadband liquid-core optical ring resonator (BLCORR) was constructed using a thinned-wall, 250-μm-inner-diameter fused silica capillary, tapered multimode optical fibers for input and output coupling, and a light-emitting diode (LED) source. When compared with standard cuvette measurements, an apparent path length as high as 5 cm was observed for methylene blue (MB). MB is a cationic dye that exhibits strong surface interaction with bare silica. Bromothymol blue (BTB), on the other hand, has a similar absorbance spectrum but does not share this same surface activity. On comparing these two dyes, the apparent path length for MB was found to reach more than 50 times that of BTB, confirming the expectation that the sensing region being probed is largely within the evanescent field at the inner surface of the capillary. The BLCORR may also inherit, from attenuated total reflection (ATR) spectroscopy, the ability to analyze highly concentrated chromophores. Concentrations of BTB as high as 10(-2) and 10(-3) M were easily distinguished from each other at the λ(max) in the BLCORR, whereas this was not the case in a 4-mm cuvette cell. Our presented device employs commercially available materials and could incorporate well into microfluidic systems. These benefits, along with the demonstrated ability to take enhanced surface absorbance measurements in a capillary, give the BLCORR potential in a variety of applications.     

Quantum nondemolition squeezing of a nanomechanical resonator

We show that the nanoresonator position can be squeezed significantly below the ground state level by measuring the nanoresonator with a quantum point contact or a single-electron transistor and applying a periodic voltage across the detector. The mechanism of squeezing is basically a generalization of quantum nondemolition measurement of an oscillator to the case of continuous measurement by a weakly coupled detector. The quantum feedback is necessary to prevent the "heating" due to measurement back-action. We also discuss a procedure of experimental verification of the squeezed state.