scholarly journals Actuation of Higher Harmonics in Large Arrays of Micromechanical Cantilevers for Expanded Resonant Peak Separation

2018 ◽  
Vol 140 (5) ◽  
Author(s):  
Nir Dick ◽  
Scott Grutzik ◽  
Christopher B. Wallin ◽  
B. Robert Ilic ◽  
Slava Krylov ◽  
...  
Keyword(s):  
Spectral Characteristics ◽  
Excitation Frequency ◽  
Laser Interferometry ◽  
Variable Length ◽  
Resonant Peak ◽  
Third Harmonic ◽  
Cantilever Arrays ◽  
Peak Separation ◽  
Sensing Applications ◽  
Harmonic Operation

A large array of elastically coupled micro cantilevers of variable length is studied experimentally and numerically. Full-scale finite element (FE) modal analysis is implemented to determine the spectral behavior of the array and to extract a global coupling matrix. A compact reduced-order (RO) model is used for numerical investigation of the array's dynamic response. Our model results show that at a given excitation frequency within a propagation band, only a finite number of beams respond. Spectral characteristics of individual cantilevers, inertially excited by an external piezoelectric actuator, were measured in vacuum using laser interferometry. The theoretical and experimental results collectively show that the resonant peaks corresponding to individual beams are clearly separated when operating in vacuum at the third harmonic. Distinct resonant peak separation, coupled with the spatially confined modal response, make higher harmonic operation of tailored, variable-length cantilever arrays well suited for a variety of resonant-based sensing applications.

scholarly journals A Comparative Study on the Oxidation of Label-Free Silver Triangular Nanoplates by Peroxides: Main Effects and Sensing Applications

Sensors ◽  
2020 ◽  
Vol 20 (17) ◽  
pp. 4832
Author(s):  
Aleksei Furletov ◽  
Vladimir Apyari ◽  
Alexey Garshev ◽  
Stanislava Dmitrienko
Keyword(s):  
Hydrogen Peroxide ◽  
Spectral Characteristics ◽  
Inorganic Ions ◽  
Label Free ◽  
Local Surface Plasmon Resonance ◽  
Tert Butyl ◽  
Sensing Applications ◽  
Tert Butyl Hydroperoxide ◽  
Resonance Band ◽  
Butyl Peroxide

Nowadays, analytical systems based on silver triangular nanoplates (AgTNPs) have been shown as good prospects for chemical sensing. However, they still remain relatively poorly studied as colorimetric probes for sensing various classes of compounds. This study shows that these nanoparticles are capable of being oxidized by peroxides, including both hydrogen peroxide and its organic derivatives. The oxidation was found to result in a decrease in the AgTNPs’ local surface plasmon resonance band intensity at 620 nm. This was proposed for peroxide-sensitive spectrophotometric determination. Five peroxides differing in their structure and number of functional groups were tested. Three of them easily oxidized AgTNPs. The effects of a structure of analytes and main exterior factors on the oxidation are discussed. The detection limits of peroxides in the selected conditions increased in the series peracetic acid < hydrogen peroxide < tert-butyl hydroperoxide, coming to 0.08, 1.6 and 24 μmol L−1, respectively. tert-Butyl peroxybenzoate and di-tert-butyl peroxide were found to have no effect on the spectral characteristics of AgTNPs. By the example of hydrogen peroxide, it was found that the determination does not interfere with 100–4000-fold quantities of common inorganic ions. The proposed approach was successfully applied to the analysis of drugs, cosmetics and model mixtures.

Resonance peak shift and dual peak separation of long-period fiber gratings for sensing applications

2001 ◽  
Vol 13 (7) ◽  
pp. 699-701 ◽  
Author(s):  
Young-Geun Han ◽  
Byeong Ha Lee ◽  
Won-Taek Han ◽  
Un-Chul Paek ◽  
Youngjoo Chung
Keyword(s):  
Peak Shift ◽  
Resonance Peak ◽  
Fiber Gratings ◽  
Long Period ◽  
Peak Separation ◽  
Sensing Applications ◽  
Long Period Fiber Gratings

Torsional Vibration of a Spur Gear System With Time-Varying and Square Nonlinearities

2013 ◽  
Author(s):  
Qian Ding ◽  
Wei Zhang
Keyword(s):  
Torsional Vibration ◽  
Excitation Frequency ◽  
Harmonic Balance Method ◽  
Spur Gear ◽  
Gear System ◽  
Phase Portraits ◽  
Resonant Peak ◽  
Time Varying ◽  
Frequency Spectra ◽  
Input Torque

This paper investigates the torsional vibration of a spur gear system with time-varying and square nonlinearities, by both the analytical method and numerical simulation. First, the equations of motion of a rotating spur gear system are established. Then a single-dof equivalent system is induced to describe the relative motion or torsional vibration of the gears. The harmonic balance method is used to obtain the steady-state response. Influence of the input torque on the response is discussed and a phenomenon, one resonant peak split up into two peaks when the input torque is high enough is revealed. Last, numerical simulations are carried out and bifurcation diagrams and amplitude-frequency curve is given by taking the excitation frequency as control parameter. Selected typical motions are also presented in detail by time-histories, phase portraits, Poincaré map and frequency spectra.

Design and control performance of a frictional tuned mass damper with bearing–shaft assemblies

2019 ◽  
Vol 25 (12) ◽  
pp. 1812-1822 ◽  
Author(s):  
Jinwei Jiang ◽  
Siu Chun Michael Ho ◽  
Nathanael J Markle ◽  
Ning Wang ◽  
Gangbing Song
Keyword(s):  
Damping Ratio ◽  
Excitation Frequency ◽  
Structural Response ◽  
Tuned Mass Damper ◽  
Resonant Peak ◽  
Equivalent Viscous Damping ◽  
Optimal Damping ◽  
Mass Damper ◽  
And Control ◽  
Equivalent Viscous Damping Ratio

This paper explores the feasibility of leveraging the damping generated by the friction between movable flange-mounted ball bearings and a stationary shaft. This bearing–shaft assembly is integrated with a tuned mass damper to form a frictional tuned mass damper (FTMD). The friction coefficient and the equivalent viscous damping ratio of the proposed FTMD were experimentally obtained based on different cases of glass, steel, and aluminum slide shafts. The proposed FTMD was modeled and simulated numerically to study its ability to suppress vibrations on a single degree of freedom structure. Furthermore, a parallel experimental validation of the FTMD was also executed to verify simulation results. Results from both experiments and simulations demonstrated that the proposed FTMD device was able to significantly improve the damping ratio of the primary structure from 0.35% to 5.326% during free vibration, and also to suppress around 90% of uncontrolled structural response at a tuned frequency. In particular, the frequency responses, among the tested shaft materials, suggested that the selected steel slide shaft practically provided a near-optimal damping coefficient, thus the proposed FTMD was able to considerably reduce structural resonant peak amplitudes over the tested excitation frequency domain.

High Temperature GaN and AlGaN Photovoltaic Detectors for UV Sensing Applications

1997 ◽  
Vol 482 ◽  
Author(s):  
J. M. Van Hove ◽  
P. P. Chow ◽  
R. Hickman ◽  
J. J. Klaassen ◽  
A. M. Wowchak ◽  
...  
Keyword(s):  
Ohmic Contacts ◽  
Elevated Temperatures ◽  
Internal Quantum Efficiency ◽  
Spectral Characteristics ◽  
Bottom Layer ◽  
Nitrogen Plasma ◽  
Type Material ◽  
Sensing Applications ◽  
Photovoltaic Detectors ◽  
P Type

AbstractAlGaN photodiode detectors are grown on (0001) sapphire by RF atomic nitrogen plasma molecular beam epitaxy. Both individual detectors and 1 × 10 element arrays are fabricated. The individual detectors have active areas of 0.5 mm2, 1.0 mm2, and 2.0 mm2. Individual elements in the l × 10 detector arrays range in size from 250×250 μm to 450×450 μm. The detectors are fabricated using a chlorine-based reactive ion etch (RIE) and refractory metal ohmic contacts. At room temperature, GaN p-i-n photovoltaic detectors show peak responsivity at 360 nm as high as 0.198 A/W, corresponding to an internal quantum efficiency of 85%. These detectors also exhibit five orders of magnitude of rejection for radiation longer than 500 nm. The electrical and spectral characteristics of these detectors are examined at elevated temperatures. The short wavelength UV responsivity remains fairly constant at elevated temperatures, while the peak responsivity actually increases with increasing temperature. The smooth surface morphology of heavily doped p-type material grown by MBE makes possible diode structures with a p-type bottom layer. The effect of the spectrally broader p-type material in the photodiode responsivity will be discussed.

scholarly journals Quantitative measurement feasibility for 3D distributions of hydrodynamic quantities in the turbulent mixing zone of two gases

1997 ◽  
Vol 15 (1) ◽  
pp. 73-82 ◽  
Author(s):  
V.P. Bashurin ◽  
V.V. Bashurov ◽  
Yu.D. Bogunenko ◽  
G.A. Bondarenko ◽  
F.A. Pletenev ◽  
...  
Keyword(s):  
Density Distribution ◽  
Turbulent Mixing ◽  
Statistical Physics ◽  
A Priori ◽  
Spectral Characteristics ◽  
Laser Interferometry ◽  
Reconstruction Method ◽  
Experimental Conditions ◽  
Mixture Density ◽  
Reconstruction Methods

In doing research on the turbulent mixing (TM) of two gases different in density, it is of great interest to study experimentally the 3D density distribution pattern of chemically nonreactive gases in the TM zone. For this purpose, noncontact and, particularly, optical techniques to obtain experimental data may be attractive. This article discusses the possibility of using pulsed laser interferometry in this application. Based on this technique, the experiment should result in the mixture density distribution integrated along the light path. Requirements for high-quality interference patterns have been analyzed in application to typical experimental conditions, to show that they may be produced with specific restrictions set on the mixture constitution. Generally, the TM zone has no symmetry. Therefore, the problem of reconstructing 3D density distributions (TDD) of gases can be solved by sufficiently providing many TM zone integral projections (or aspects). It is technically difficult and expensive to achieve this large number of aspects (N> 10). Therefore, it is essential that a reconstruction method be selected to allow the solution of the problem with the least possible number of aspects. Given that the experiment data are incomplete, the reconstruction methods that are based on the concept of maximum data entropy did well. Information a priori about the solution to be sought for an isobaric gas mixture is that its each constituent has invariable density. Thus, a functional data entropy can be defined that is similar to Fermi gas in statistical physics. An algorithm has been suggested for reconstruction as a modified maximum-bounded entropy procedure (Bashurin et al. 1995). This makes reasonable good reconstruction achievable even with as few aspects as N = 4. Experiments on the study of TM of a propane jet in air using a four-aspects laser interferometer were provided and reconstruction of propane concentration distribution was conducted. The results allow determination of the TM zone spectral characteristics.

scholarly journals Experimental Demonstration of Temperature Sensing with Packaged Glass Bottle Microresonators

Sensors ◽  
2018 ◽  
Vol 18 (12) ◽  
pp. 4321 ◽  
Author(s):  
Jonas Herter ◽  
Valentin Wunderlich ◽  
Christian Janeczka ◽  
Vanessa Zamora
Keyword(s):  
Limit Of Detection ◽  
Spectral Characteristics ◽  
Temperature Sensing ◽  
Glass Bottle ◽  
Tapered Fiber ◽  
Large Coupling ◽  
Sensing Applications ◽  
Assembly Method ◽  
Spectral Ranges ◽  
Q Factors

Whispering gallery mode (WGM) glass bottle microresonators are potential highly sensitive structures for a variety of physical and bio-chemical sensing applications. In this paper, we experimentally demonstrate the practical use of glass bottle resonators as temperature sensors. The basic parameters, such as WGM resonance wavelengths, free spectral ranges, and Q factors, have been investigated by coupling light from a tapered fiber to the bottle structure. We show the spectral characteristics of the WGMs by choosing different bottle dimensions and taper diameters. For practical measurements, a robust 3D-printed package that includes the bottle resonator and the tapered fiber has been proposed. The packaged bottle has a central diameter Dc = 207 µm and a length L = 300 µm. Temperature sensing experiments were also performed. A linear response of the WGM shifts as a function of the temperature is confirmed. The fitted experimental data indicate a temperature sensitivity of 10.5 pm/K at λ ~ 1550 nm, resulting in a limit of detection of 0.06 K. These values can be compared with values reported for other WGM resonators. Additionally, bottle resonators are made with simple splicing methods and their assembly method can be easily defined due to large coupling tolerances.

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