scholarly journals A Biomimetic Miniaturized Microphone Array for Sound Direction Finding Applications Based on a Phase-Enhanced Electrical Coupling Network

Sensors ◽  
2019 ◽  
Vol 19 (16) ◽  
pp. 3469
Author(s):  
Chien-Chang Huang ◽  
Chien-Hao Liu
Keyword(s):  
Signal To Noise Ratio ◽  
Microphone Array ◽  
Incident Angle ◽  
Power Level ◽  
Electrical Coupling ◽  
Direction Finding ◽  
Separation Distance ◽  
Mechanical Coupling ◽  
Sound Direction ◽  
Good Signal

In this research, we proposed a miniaturized two-element sensor array inspired by Ormia Ochracea for sound direction finding applications. In contrast to the convectional approach of using mechanical coupling structures for enlarging the intensity differences, we exploited an electrical coupling network circuit composed of lumped elements to enhance the phase differences and extract the optimized output power for good signal-to-noise ratio. The separation distance between two sensors could be reduced from 0.5 wavelength to 0.1 wavelength 3.43 mm at the operation frequency of 10 kHz) for determining the angle of arrivals. The main advantages of the proposed device include low power losses, flexible designs, and wide operation bandwidths. A prototype was designed, fabricated, and experiments examined within a sound anechoic chamber. It was demonstrated that the proposed device had a phase enhancement of 110 ∘ at the incident angle of 90 ∘ and the normalized power level of −2.16 dB at both output ports. The received power levels of our device were 3 dB higher than those of the transformer-type direction-finding system. In addition, our proposed device could operate in the frequency range from 8 kHz to 12 kHz with a tunable capacitor. The research results are expected to be beneficial for the compact sonar or radar systems.

scholarly journals Interphotoreceptor coupling: an evolutionary perspective

2021 ◽  
Author(s):  
Lorenzo Cangiano ◽  
Sabrina Asteriti
Keyword(s):  
Visual Information ◽  
Signal To Noise Ratio ◽  
Electrical Coupling ◽  
Physiological Role ◽  
Cellular Processes ◽  
Contact Points ◽  
Highly Sensitive ◽  
The Many ◽  
The Impact

AbstractIn the vertebrate retina, signals generated by cones of different spectral preference and by highly sensitive rod photoreceptors interact at various levels to extract salient visual information. The first opportunity for such interaction is offered by electrical coupling of the photoreceptors themselves, which is mediated by gap junctions located at the contact points of specialised cellular processes: synaptic terminals, telodendria and radial fins. Here, we examine the evolutionary pressures for and against interphotoreceptor coupling, which are likely to have shaped how coupling is deployed in different species. The impact of coupling on signal to noise ratio, spatial acuity, contrast sensitivity, absolute and increment threshold, retinal signal flow and colour discrimination is discussed while emphasising available data from a variety of vertebrate models spanning from lampreys to primates. We highlight the many gaps in our knowledge, persisting discrepancies in the literature, as well as some major unanswered questions on the actual extent and physiological role of cone-cone, rod-cone and rod-rod communication. Lastly, we point toward limited but intriguing evidence suggestive of the ancestral form of coupling among ciliary photoreceptors.

Narrow-frequency sharp-angular filters using all-dielectric cascaded meta-gratings

Nanophotonics ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 3443-3450 ◽  
Author(s):  
Wei-Nan Liu ◽  
Rui Chen ◽  
Wei-Yi Shi ◽  
Ke-Bo Zeng ◽  
Fu-Li Zhao ◽  
...  
Keyword(s):  
Thin Film ◽  
Signal To Noise Ratio ◽  
Incident Angle ◽  
Design Strategy ◽  
Transmission Peak ◽  
High Signal ◽  
Waveguide Array ◽  
Signal To Noise ◽  
Center Wavelength ◽  
Noise Ratio

AbstractSelective transmission or filtering always responds to either frequency or incident angle, so as hardly to maximize signal-to-noise ratio in communication, detection and sensing. Here, we propose compact meta-filters of narrow-frequency sharp-angular transmission peak along with broad omnidirectional reflection sidebands, in all-dielectric cascaded subwavelength meta-gratings. The inherent collective resonance of waveguide-array modes and thin film approximation of meta-grating are employed as the design strategy. A unity transmission peak, locating at the incident angle of 44.4° and the center wavelength of 1550 nm, is demonstrated in a silicon meta-filter consisting of two-layer silicon rectangular meta-grating. These findings provide possibilities in cascaded meta-gratings spectroscopic design and alternative utilities for high signal-to-noise ratio applications in focus-free spatial filtering and anti-noise systems in telecommunications.

scholarly journals A large area diamond-based beam tagging hodoscope for ion therapy monitoring

2018 ◽  
Vol 170 ◽  
pp. 09005 ◽  
Author(s):  
M.-L. Gallin-Martel ◽  
L. Abbassi ◽  
A. Bes ◽  
G. Bosson ◽  
J. Collot ◽  
...  
Keyword(s):  
Detection Efficiency ◽  
Signal To Noise Ratio ◽  
Therapy Monitoring ◽  
Chemical Vapor ◽  
X Rays ◽  
Reaction Products ◽  
Large Area ◽  
Position Measurement ◽  
Set Up ◽  
Good Signal

The MoniDiam project is part of the French national collaboration CLaRyS (Contrôle en Ligne de l’hAdronthérapie par RaYonnements Secondaires) for on-line monitoring of hadron therapy. It relies on the imaging of nuclear reaction products that is related to the ion range. The goal here is to provide large area beam detectors with a high detection efficiency for carbon or proton beams giving time and position measurement at 100 MHz count rates (beam tagging hodoscope). High radiation hardness and intrinsic electronic properties make diamonds reliable and very fast detectors with a good signal to noise ratio. Commercial Chemical Vapor Deposited (CVD) poly-crystalline, heteroepitaxial and monocrystalline diamonds were studied. Their applicability as a particle detector was investigated using α and β radioactive sources, 95 MeV/u carbon ion beams at GANIL and 8.5 keV X-ray photon bunches from ESRF. This facility offers the unique capability of providing a focused (~1 μm) beam in bunches of 100 ps duration, with an almost uniform energy deposition in the irradiated detector volume, therefore mimicking the interaction of single ions. A signal rise time resolution ranging from 20 to 90 ps rms and an energy resolution of 7 to 9% were measured using diamonds with aluminum disk shaped surface metallization. This enabled us to conclude that polycrystalline CVD diamond detectors are good candidates for our beam tagging hodoscope development. Recently, double-side stripped metallized diamonds were tested using the XBIC (X Rays Beam Induced Current) set-up of the ID21 beamline at ESRF which permits us to evaluate the capability of diamond to be used as position sensitive detector. The final detector will consist in a mosaic arrangement of double-side stripped diamond sensors read out by a dedicated fast-integrated electronics of several hundreds of channels.

scholarly journals Error Correction for FSI-Based System without Cooperative Target Using an Adaptive Filtering Method and a Phase-Matching Mosaic Algorithm

2018 ◽  
Vol 8 (10) ◽  
pp. 1954 ◽  
Author(s):  
Xing-Ting Xiong ◽  
Xing-Hua Qu ◽  
Fu-Min Zhang
Keyword(s):  
Adaptive Filtering ◽  
Signal To Noise Ratio ◽  
Incident Angle ◽  
External Cavity ◽  
Phase Matching ◽  
Maximum Deviation ◽  
External Cavity Laser ◽  
Filtering Method ◽  
System A ◽  
Sampling Points

In our frequency scanning interferometry-based (FSI-based) absolute distance measurement system, a frequency sampling method is used to eliminate the influence of laser tuning nonlinearity. However, because the external cavity laser (ECL) has been used for five years, factors such as the mode hopping of the ECL and the low signal-to-noise ratio (SNR) in a non-cooperative target measurement bring new problems, including erroneous sampling points, phase jumps, and interfering signals. This article analyzes the impacts of the erroneous sampling points and interfering signals on the accuracy of measurement, and then proposes an adaptive filtering method to eliminate the influence. In addition, a phase-matching mosaic algorithm is used to eliminate the phase jump, and a segmentation mosaic algorithm is used to improve the data processing speed. The result of the simulation proves the efficiency of our method. In experiments, the measured target was located at eight different positions on a precise guide rail, and the incident angle was 12 degrees. The maximum deviation of the measured results between the FSI-based system and the He-Ne interferometer was 9.6 μm, and the maximum mean square error of our method was 2.4 μm, which approached the Cramer-Rao lower bound (CRLB) of 0.8 μm.

scholarly journals Magnetic properties of cobalt microwires measured by piezoresistive cantilever magnetometry

2014 ◽  
Vol 1 (1) ◽  
Author(s):  
G. Tosolini ◽  
J. M. Michalik ◽  
R. Córdoba ◽  
J. M. de Teresa ◽  
F. Pérez-Murano ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Room Temperature ◽  
Signal To Noise Ratio ◽  
Static Deflection ◽  
Magnetic Structures ◽  
Dual Beam ◽  
Piezoresistive Cantilevers ◽  
Good Signal ◽  
The Magnetic Field

AbstractWe present the magnetic characterization of cobalt wires grown by focused electron beam-induced deposition (FEBID) and studied using static piezoresistive cantilever magnetometry. We have used previously developed high force sensitive submicron-thick silicon piezoresistive cantilevers. High quality polycrystalline cobalt microwires have been grown by FEBID onto the free end of the cantilevers using dual beam equipment. In the presence of an external magnetic field, the magnetic cobalt wires become magnetized, which leads to the magnetic field dependent static deflection of the cantilevers. We show that the piezoresistive signal from the cantilevers, corresponding to a maximum force of about 1 nN, can be measured as a function of the applied magnetic field with a good signal to noise ratio at room temperature. The results highlight the flexibility of the FEBID technique for the growth of magnetic structures on specific substrates, in this case piezoresistive cantilevers.

Estimating Optimum Filter Length in Linear Prediction

1997 ◽  
Vol 51 (5) ◽  
pp. 718-720 ◽  
Author(s):  
O.-P. Sievänen
Keyword(s):  
Raman Spectra ◽  
Prediction Error ◽  
Linear Prediction ◽  
Signal To Noise Ratio ◽  
New Method ◽  
Signal To Noise ◽  
Filter Length ◽  
Optimum Filter ◽  
Good Signal ◽  
Prediction Filter

In this article a new method to estimate optimum filter length in linear prediction is described. Linear prediction was used to enhance resolution of a spectrum. In particular, the dependence of prediction error on filter length has been studied. With calculations of simulated spectra it is shown that the prediction error falls rapidly when the filter length attains its optimum value. This effect is quite pronounced when the spectrum has a good signal-to-noise ratio and the modified covariance method is used to calculate prediction filter coefficients. The method is illustrated with applications to real Raman spectra.

scholarly journals Microdrilled tapers to enhance optical fiber lasers for sensing

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
R. A. Perez-Herrera ◽  
M. Bravo ◽  
P. Roldan-Varona ◽  
D. Leandro ◽  
L. Rodriguez-Cobo ◽  
...  
Keyword(s):  
Optical Fiber ◽  
Optical Fibers ◽  
Fiber Lasers ◽  
Signal To Noise Ratio ◽  
Power Level ◽  
Single Mode ◽  
Optical Signal ◽  
Single Mode Fiber ◽  
Output Power Level ◽  
Linear Cavity

AbstractIn this work, an experimental analysis of the performance of different types of quasi-randomly distributed reflectors inscribed into a single-mode fiber as a sensing mirror is presented. These artificially-controlled backscattering fiber reflectors are used in short linear cavity fiber lasers. In particular, laser emission and sensor application features are analyzed when employing optical tapered fibers, micro-drilled optical fibers and 50 μm-waist or 100 μm-waist micro-drilled tapered fibers (MDTF). Single-wavelength laser with an output power level of about 8.2 dBm and an optical signal-to-noise ratio of 45 dB were measured when employing a 50 μm-waist micro-drilled tapered optical fiber. The achieved temperature sensitivities were similar to those of FBGs; however, the strain sensitivity improved more than one order of magnitude in comparison with FBG sensors, attaining slope sensitivities as good as 18.1 pm/με when using a 50 μm-waist MDTF as distributed reflector.

scholarly journals A NOVEL APPROACH OF CLUSTERING FOR ENHANCED LIFETIME IN WIRELESS SENSOR NETWORK

2017 ◽  
Vol 16 (7) ◽  
pp. 7031-7039
Author(s):  
Chamanpreet Kaur ◽  
Vikramjit Singh
Keyword(s):  
Wireless Sensor Network ◽  
Sensor Network ◽  
Power Level ◽  
Research Work ◽  
Cluster Head ◽  
Mobile Node ◽  
Separation Distance ◽  
Residual Energy ◽  
Base Station ◽  
Wireless Sensor

Wireless sensor network has revolutionized the way computing and software services are delivered to the clients on demand. Our research work proposed a new method for cluster head selection having less computational complexity. It was also found that the modified approach has improved performance to that of the other clustering approaches. The cluster head election mechanism will include various parameters like maximum residual energy of a node, minimum separation distance and minimum distance to the mobile node. Each CH will create a TDMA schedule for the member nodes to transmit the data. Nodes will have various level of power for signal amplification. The three levels of power are used for amplifying the signal. As the member node will send only its own data to the cluster head, the power level of the member node is set to low. The cluster head will send the data of the whole cluster to the mobile node, therefore the power level of the cluster head is set to medium. High power level is used for mobile node which will send the data of the complete sector to the base station. Using low energy level for intra cluster transmissions (within the cluster) with respect to cluster head to mobile node transmission leads in saving much amount of energy. Moreover, multi-power levels also reduce the packet drop ratio, collisions and/ or interference for other signals. It was found that the proposed algorithm gives a much improved network lifetime as compared to existing work. Based on our model, multiple experiments have been conducted using different values of initial energy.

The far-infrared spectrum of hydrogen sulfide. The (000) rotational constants of , , and

1983 ◽  
Vol 61 (10) ◽  
pp. 1462-1473 ◽  
Author(s):  
J.-M. Flaud ◽  
C. Camy-Peyret ◽  
J. W. C. Johns
Keyword(s):  
Hydrogen Sulfide ◽  
Signal To Noise Ratio ◽  
Far Infrared ◽  
Infrared Region ◽  
Rotational Constants ◽  
Pure Rotation ◽  
Isotopic Species ◽  
Least Squares Fit ◽  
Rotational Transitions ◽  
Good Signal

The pure rotation spectrum of hydrogen sulfide has been recorded between 50 and 320 cm−1 with a Fourier transform spectrometer at an apodized resolution of 0.005 cm−1. This high resolution and a good signal-to-noise ratio lead to a significant improvement in the accuracy of the wavenumbers of the rotational transitions of the three isotopic species [Formula: see text], [Formula: see text], and [Formula: see text] that were observed in natural abundance. These rotational transitions, together with the available microwave data, have been included in a least squares fit leading to the determination of precise rotational constants for each isotopic species. Finally, these constants have been used to calculate precisely the absorption of natural hydrogen sulfide in the far-infrared region of the spectrum.

Physical Properties and Structure of the Near Subsurface in the Săcel Area, Romania, from Shallow Seismic Measurements

2019 ◽  
Vol 24 (1) ◽  
pp. 151-158
Author(s):  
Ionelia Panea
Keyword(s):  
Wave Velocity ◽  
Signal To Noise Ratio ◽  
Soil Surface ◽  
Geological Structure ◽  
P Wave ◽  
S Wave ◽  
Sedimentary Deposits ◽  
Shallow Seismic ◽  
P Wave Velocity ◽  
Good Signal

Results are presented for shallow seismic reflection measurements performed southwest of Săcel village in Romania for the purpose of obtaining information about the geological structure in the near subsurface. The P-wave and S-wave velocity distributions were also obtained below the soil surface. The measurements were performed along a nearly linear profile on the top of an elongated hill. Most of the shot gathers were characterized by a good signal-to-noise ratio. A depth-converted migrated section was obtained after the processing of shot gathers, on which an image of sedimentary deposits with various thicknesses, separated by shallow faults until a depth of about 80 m, were observed. The P-wave and S-wave velocity-depth models for two segments were of considerable interest for a geotechnical study proposed for the construction of a windmill park. The two- and three-layered P-wave velocity-depth models were comparable until depths of about 10 m after first-arrival traveltime inversions. The lateral variations in the subsurface geological structure and lithology reflected the variations in the P-wave velocity values from both models. The S-wave velocity-depth models for comparable depth intervals were similar to those from the P-wave velocity-depth models. Reliable S-wave velocity distributions were obtained after inversion of fundamental-mode and higher-mode surface waves.

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