Characterization of a Multilayered SAW Pressure Sensor with Low Temperature Variability

2014 ◽  
Vol 656 ◽  
pp. 413-422 ◽  
Author(s):  
Bing Zhang ◽  
Hong Hu ◽  
R. Ben-Mrad
Keyword(s):  
Low Temperature ◽  
Phase Angle ◽  
Coupling Coefficient ◽  
Pressure Sensors ◽  
Time Domain Analysis ◽  
Domain Analysis ◽  
Frequency Domain Analysis ◽  
Propagation Characteristics ◽  
Rf Signal

A method to reduce temperature effects in SAW pressure sensors is presented. A layer of SiO2 is deposited on the surface of 128YX LiNbO3 in order to achieve a high coupling coefficient (κ2) as well as a low temperature coefficient of delay (TCD). The FEM tool COMSOL Multiphysics is used to estimate the phase velocity and frequency of the input RF signal using an eigenfrequency analysis. Then by using a time domain analysis, a surface acoustic wave (SAW) is generated by IDTs and its wave propagation characteristics are obtained. During this process, the boundary reflection is removed by adding a perfectly matched layer (PML). The reflected signal on the IDT can be detected; as such the phase angle is calculated. By applying different pressures to the sensor, a relationship between pressure and phase angle is determined. Using frequency domain analysis, the coupling coefficient is computed with high accuracy. The TCD is calculated at different SiO2 thicknesses and the SiO2 thickness corresponding to a zero TCD and high coupling coefficient is obtained. A prototype is tested to validate these values.

scholarly journals Assessment of Cardiac Autonomic Function in Relation to Methylmercury Neurotoxicity

Toxics ◽  
2018 ◽  
Vol 6 (3) ◽  
pp. 38 ◽  
Author(s):  
Kanae Karita ◽  
Toyoto Iwata ◽  
Eri Maeda ◽  
Mineshi Sakamoto ◽  
Katsuyuki Murata
Keyword(s):  
Time Domain Analysis ◽  
Domain Analysis ◽  
Frequency Domain Analysis ◽  
Human Populations ◽  
Cardiac Autonomic Function ◽  
Risk Characterization ◽  
Frequency Domains ◽  
Methylmercury Exposure ◽  
Spectral Components

After the European Food Safety Authority reviewed reports of methylmercury and heart rate variability (HRV) in 2012, the panel concluded that, although some studies of cardiac autonomy suggested an autonomic effect of methylmercury, the results were inconsistent among studies and the implications for health were unclear. In this study, we reconsider this association by adding a perspective on the physiological context. Cardiovascular rhythmicity is usually studied within different frequency domains of HRV. Three spectral components are usually detected; in humans these are centered at <0.04 Hz, 0.15 Hz (LF), and 0.3 Hz (HF). LF and HF (sympathetic and parasympathetic activities, respectively) are evaluated in terms of frequency and power. By searching PubMed, we identified 13 studies examining the effect of methylmercury exposure on HRV in human populations in the Faroe Islands, the Seychelles and other countries. Considering both reduced HRV and sympathodominant state (i.e., lower HF, higher LF, or higher LF/HF ratio) as autonomic abnormality, eight of them showed the significant association with methylmercury exposure. Five studies failed to demonstrate any significant association. In conclusion, these data suggest that increased methylmercury exposure was consistently associated with autonomic abnormality, though the influence of methylmercury on HRV (e.g., LF) might differ for prenatal and postnatal exposures. The results with HRV should be included in the risk characterization of methylmercury. The HRV parameters calculated by frequency domain analysis appear to be more sensitive to methylmercury exposure than those by time domain analysis.

Fouling Detection in Low Speed Fan Using Near-Field DIY Sound Pressure Sensors

2016 ◽  
Author(s):  
Alessandro Corsini ◽  
Cecilia Tortora
Keyword(s):  
Near Field ◽  
Pressure Sensors ◽  
Experimental Tests ◽  
Time Domain Analysis ◽  
Domain Analysis ◽  
Frequency Domain Analysis ◽  
Rotating Stall ◽  
Axial Fan ◽  
Time Resolved ◽  
Low Speed

This work investigates the dynamics of rotating stall of a low speed axial fan in presence of fouling on the blades. Rotating stall is an aerodynamic issue of recognized importance in turbomachinery. The combination of rotating stall and presence of particles of dust and dirt from the surrounding environment, may lead to further issues in terms of performance, stall limit and blades life. In this paper the identification of the rotating stall pattern is carried out using time-resolved sound measurements in the far field region by means of a condenser microphone. The experimental tests are carried out with various geometries of fouling in order to evaluate the system ability to detect acoustically fouling and rotating stall. The results have been validated against state of the art techniques described in the literature. The acquired signals have been analysed using frequency domain analysis, and time domain analysis using a phase space reconstruction inspired technique. Both of the approaches demonstrate a modification of the stall dynamics in the low speed fan and allow the identification of diverse stall precursors and fouling presence.

scholarly journals Analysis of Three-Phase Wye-Delta Connected LLC

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3606
Author(s):  
Jing-Yuan Lin ◽  
Chuan-Ting Chen ◽  
Kuan-Hung Chen ◽  
Yi-Feng Lin
Keyword(s):  
Frequency Domain ◽  
Time Domain ◽  
Operation Time ◽  
Time Domain Analysis ◽  
Domain Analysis ◽  
Frequency Domain Analysis ◽  
Complete Analysis ◽  
Plane Analysis ◽  
Analysis Methods ◽  
Three Phase

Three-phase wye–delta LLC topology is suitable for voltage step down and high output current, and has been used in the industry for some time, e.g., for server power and EV charger. However, no comprehensive circuit analysis has been performed for three-phase wye–delta LLC. This paper provides complete analysis methods for three-phase wye–delta LLC. The analysis methods include circuit operation, time domain analysis, frequency domain analysis, and state–plane analysis. Circuit operation helps determine the circuit composition and operation sequence. Time domain analysis helps understand the detail operation, equivalent circuit model, and circuit equation. Frequency domain analysis helps obtain the curve of the transfer function and assists in circuit design. State–plane analysis is used for optimal trajectory control (OTC). These analyses not only can calculate the voltage/current stress, but can also help design three-phase wye-delta connected LLC and provide the OTC control reference. In addition, this paper uses PSIM simulation to verify the correctness of analysis. At the end, a 5-kW three-phase wye–delta LLC prototype is realized. The specification of the prototype is a DC input voltage of 380 V and output voltage/current of 48 V/105 A. The peak efficiency is 96.57%.

Pulse Wave Analysis of Traditional Chinese Medicine Based on Hemodynamics Principles**

2011 ◽  
pp. 194-203
Author(s):  
Rui Guo ◽  
Yiqin Wang ◽  
Haixia Yan ◽  
Fufeng Li ◽  
Jianjun Yan ◽  
...  
Keyword(s):  
Chinese Medicine ◽  
Traditional Chinese Medicine ◽  
Clinical Significance ◽  
Pulse Wave ◽  
Time Domain Analysis ◽  
Domain Analysis ◽  
Frequency Domain Analysis ◽  
Pulse Velocity ◽  
Reflection Coefficients ◽  
Feature Parameters

From the perspective of hemodynamics principles, the pressure pulse wave marked in the radial artery is the comprehensive result of pulse wave propagation and reflection in the arterial conduit. The most common pulse charts (also called pulse wave) obtained by Traditional Chinese Medicine (TCM) pulse-taking technique, if quantified and standardized, may become a universal and valuable diagnostic tool. The methods of feature extraction of TCM pulse charts currently involve time-domain analysis, frequency-domain analysis and time-frequency joint analysis. The feature parameters extracted by these methods have no definite clinical significance. Therefore, these feature parameters cannot essentially differentiate different types of TCM pulse. In this chapter, the harmonic analysis method was applied to analyze the common TCM pulse charts (plain pulse, wiry pulse, slippery pulse). Velocity and reflectivity coefficients of pulse were calculated. We found that wave velocities and reflection coefficients of different TCM pulse have different distributions. Furthermore, we studied the clinical significance of velocities and reflection coefficients. The result suggests that wave velocity and reflection coefficient are the feature parameters of TCM pulse with physiological and pathological significance, which can be used to interpret formation of Chinese medicine pulse. Our study reveals the mechanism of TCM pulse formation and promotes non-invasive TCM pulse diagnostic method.

Modelling of Electrohydraulic Systems with Transmission Lines using Modal Approximations

1988 ◽  
Vol 202 (3) ◽  
pp. 153-163 ◽  
Author(s):  
J Watton
Keyword(s):  
Transmission Lines ◽  
Method Of Characteristics ◽  
Digital Simulation ◽  
Time Domain Analysis ◽  
Domain Analysis ◽  
Frequency Domain Analysis ◽  
Specific Form ◽  
Lumped Parameter ◽  
Good Comparison ◽  
Distributed Friction

The method of modal approximation to the distributed friction transmission line functions via frequency-domain analysis is briefly discussed. A specific form is then derived which allows time-domain analysis to be easily pursued using a digital simulation package approach. The method is applied to a highly non-linear servo-valve controlled motor system and a good comparison between experiment and theory is shown. A comparison is also made with previous work using the method of characteristics, and natural frequency predictions are also compared with some common lumped parameter approximations.

scholarly journals A New Conceptual Design and Dynamic Analysis of a Spar-Type Offshore Wind Turbine Combined with a Moonpool

Energies ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3737 ◽  
Author(s):  
Thanh Dam Pham ◽  
Hyunkyoung Shin
Keyword(s):  
Wind Turbine ◽  
Bending Moment ◽  
Time Domain Analysis ◽  
Domain Analysis ◽  
Frequency Domain Analysis ◽  
Dynamic Responses ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Operational Conditions ◽  
Floating Offshore Wind Turbines

Floating offshore wind turbines promise to provide an abundant source of energy. Currently, much attention is being paid to the efficient performance and the economics of floating wind systems. This paper aims to develop a spar-type platform to support a 5-MW reference wind turbine at a water depth of 150 m. The spar-type platform includes a moonpool at the center. The design optimization process is composed of three steps; the first step uses a spreadsheet to calculate the platform dimensions; the second step is a frequency domain analysis of the responses in wave conditions; and the final step is a fully coupled simulation time domain analysis to obtain the dynamic responses in combined wind, wave, and current conditions. By having a water column inside the open moonpool, the system’s dynamic responses to horizontal and rotating motions are significantly reduced. Reduction of these motions leads to a reduction in the nacelle acceleration and tower base bending moment. On the basic of optimization processes, a spar-type platform combined with a moonpool is suggested, which has good performance in both operational conditions and extreme conditions.

Hydrostatic Stability and Global Performance Analysis for Set TLP

2016 ◽  
Author(s):  
R. H. Yuck ◽  
S. J. Kim ◽  
S. U. Sung ◽  
H. J. Kim ◽  
D. Y. Lee ◽  
...  
Keyword(s):  
Time Domain Analysis ◽  
Domain Analysis ◽  
Frequency Domain Analysis ◽  
Hydrodynamic Characteristics ◽  
Wave Load ◽  
Operational Conditions ◽  
Western Africa ◽  
Structural Reinforcement ◽  
Global Performance ◽  
Tendon Tension

SET (Samsung Enhanced hull for Tendon) TLP (Tension Leg Platform) has been designed as an innovative TLP hull form with optimized number of tendons compared to conventional TLP design. SHI (Samsung Heavy Industries) designed the SET TLP to have the minimized hull weight with narrow and thin pontoon which results in the less number of tendons without any outboard extension of column or pontoon. The SET TLP has 8 tendons which are evenly attached along with the octagonal shaped-ring pontoon. The unique shape of octagonal ring pontoon distributes the wave load and concentrated tendon loads in larger areas, which can minimize the structural reinforcement. To verify the feasibility of the proposed hull concept with regard to the hydrostatic/hydrodynamic characteristics and tendon design, the numerical analyses for the hydrostatic stability and global performance are carried out. Hydrostatic stability is investigated for all the possible loading cases such as float-off, wet transit, tendon installation and operational conditions, and the proper tank compartments are achieved for all the scenarios without using any temporary stability module. The global performance is validated for all the possible combinations of wave, swell, wind, current and/or squall for a site in Western Africa. Through the frequency-domain analysis and nonlinear time-domain analysis as well, the essential items such as the maximum offset/set-down/top tendon tension, minimum bottom tendon tension are examined and confirms that the certain design criteria of TLP operation are satisfied.

A Frequency Domain Analysis of Learning Control

1994 ◽  
Vol 116 (4) ◽  
pp. 781-786 ◽  
Author(s):  
C. J. Goh
Keyword(s):  
Frequency Domain ◽  
Time Domain ◽  
Linear Time ◽  
Planning Horizon ◽  
Time Domain Analysis ◽  
Learning Control ◽  
Domain Analysis ◽  
Frequency Domain Analysis ◽  
Convergence Criterion ◽  
The Time Domain

The convergence of learning control is traditionally analyzed in the time domain. This is because a finite planning horizon is often assumed and the analysis in time domain can be extended to time-varying and nonlinear systems. For linear time-invariant (LTI) systems with infinite planning horizon, however, we show that simple frequency domain techniques can be used to quickly derive several interesting results not amenable to time-domain analysis, such as predicting the rate of convergence or the design of optimum learning control law. We explain a paradox arising from applying the finite time convergence criterion to the infinite time learning control problem, and propose the use of current error feedback for controlling possibly unstable systems.

Sign in / Sign up

Export Citation Format

Share Document