An 8–10 GHz upconversion mixer, with a low-frequency calibration loop resulting in better than −73dBc in-band spurs

Background: Electrical stimulation is increasingly relevant in a variety of medical treatments. In this study, surface electrical stimulation was evaluated as a method to non-invasively target a neural function, specifically natural sensation in the distal limbs. Method: Electrodes were placed over the median and ulnar nerves at the elbow and the common peroneal and lateral sural cutaneous nerves at the knee. Strength-duration curves for sensation were compared between nerves. The location, modality, and intensity of each sensation were also analyzed. In an effort to evoke natural sensations, several patterned waveforms were evaluated. Results: Distal sensation was obtained in all but one of the 48 nerves tested in able-bodied subjects and in the two nerves from subjects with an amputation. Increasing the pulse amplitude of the stimulus caused an increase in the area and magnitude of the sensation in a majority of subjects. A low frequency waveform evoked a tapping or tapping-like sensation in 29 out of the 31 able-bodied subjects and a sensation that could be considered natural in two subjects with an amputation. This waveform performed better than other patterned waveforms that had proven effective during implanted extra-neural stimulation. Conclusion: Surface electrical stimulation has the potential to be a powerful, non-invasive tool for activation of the nervous system. These results suggest that a tapping sensation in the distal extremity can be evoked in most able-bodied individuals and that targeting the nerve trunk from the surface is a valid method to evoke sensation in the phantom limb of individuals with an amputation for short term applications.

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On the Effects of Mistuning a Force-Excited System Containing a Quasi-Zero-Stiffness Vibration Isolator

Journal of Vibration and Acoustics ◽

10.1115/1.4029689 ◽

2015 ◽

Vol 137 (4) ◽

Cited By ~ 19

Author(s):

Ali Abolfathi ◽

M. J. Brennan ◽

T. P. Waters ◽

B. Tang

Keyword(s):

Vibration Isolation ◽

Dynamic Stiffness ◽

Low Frequency ◽

Vibration Isolator ◽

Linear Vibration ◽

Vibration Isolators ◽

Zero Dynamic ◽

Low Frequency Vibration ◽

Excited System ◽

Better Than

Nonlinear isolators with high-static-low-dynamic-stiffness have received considerable attention in the recent literature due to their performance benefits compared to linear vibration isolators. A quasi-zero-stiffness (QZS) isolator is a particular case of this type of isolator, which has a zero dynamic stiffness at the static equilibrium position. These types of isolators can be used to achieve very low frequency vibration isolation, but a drawback is that they have purely hardening stiffness behavior. If something occurs to destroy the symmetry of the system, for example, by an additional static load being applied to the isolator during operation, or by the incorrect mass being suspended on the isolator, then the isolator behavior will change dramatically. The question is whether this will be detrimental to the performance of the isolator and this is addressed in this paper. The analysis in this paper shows that although the asymmetry will degrade the performance of the isolator compared to the perfectly tuned case, it will still perform better than the corresponding linear isolator provided that the amplitude of excitation is not too large.

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Experimental Research about the Application of ER Elastomer in the Shock Absorber

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.641-642.371 ◽

2013 ◽

Vol 641-642 ◽

pp. 371-376 ◽

Cited By ~ 7

Author(s):

Shi Sha Zhu ◽

Xue Peng Qian ◽

Hao He ◽

Quan Fu Zhang

Keyword(s):

Electric Field ◽

External Electric Field ◽

Shock Absorber ◽

Hybrid Control ◽

Excitation Frequency ◽

Low Frequency ◽

Structural Vibration ◽

Shear Mode ◽

Response Performance ◽

Better Than

When the Electrorheological elastomer (ERE) is embedded into intelligence structure system, the structure damping and stiffness of the system can be changed quickly and reversibly under an external electric field. Thus, the application of the Electrorheological elastomer in the active and passive hybrid control of structural vibration has already attracted people's wide attention. In this paper, three types of ER elastomer were prepared based on barium titanate, starch, then the microstructure of ER elastomer was observed and the mechanical properties were analyzed; a shear mode ERE shock absorber was designed, the vibration response performance of which was experimentally evaluated under various excitation frequency with or without the applied field. The experimental results showed that the damping and stiffness of the shock absorber could be modified with a changing external electric field, whose macro-features was that the damping coefficient increased with the increase of the electric field, and the damping effect in the high frequency was better than in the low frequency.

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Low-frequency calibration of a multidimensional acoustic intensity probe for application to rocket noise

The Journal of the Acoustical Society of America ◽

10.1121/1.3655007 ◽

2011 ◽

Vol 130 (4) ◽

pp. 2512-2512

Author(s):

Jarom H. Giraud ◽

Kent L. Gee ◽

Scott D. Sommerfeldt ◽

R. Troy Taylor ◽

Jonathan D. Blotter

Keyword(s):

Low Frequency ◽

Acoustic Intensity ◽

Frequency Calibration

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Lung nodule conspicuity using unsharp mask filters with storage-phosphor-based computed radiography

Acta Radiologica ◽

10.1080/02841859709171250 ◽

1997 ◽

Vol 38 (1) ◽

pp. 99-103 ◽

Cited By ~ 2

Author(s):

F. Li ◽

S. Sone ◽

K. Kiyono

Keyword(s):

Roc Analysis ◽

Computed Radiography ◽

Lung Nodule ◽

Low Frequency ◽

Lung Nodules ◽

Cancer Type ◽

Storage Phosphor ◽

Very Low Frequency ◽

Unsharp Mask ◽

Better Than

Purpose: To compare the performance of various types of unsharp mask filter applied in storage-phosphor-based computed radiography (SR), and to improve the detection of faint nodules of the lung cancer type. Material and Methods: A total of 120 SR radiographs were obtained by means of an anthropomorphous chest phantom and a combination of 3 types of small simulated nodule (5-mm sphere-shaped, and 5-mm and 10-mm hemisphere-shaped) placed on the phantom's surface. Eight combinations of nodule site were selected from 16 predetermined chosen sites, and 5 types of parameter were used for unsharp mask filtering. Eight observers evaluated the images, and the detectability of the lung nodules was evaluated from the images by a ROC analysis. Results: The visibility of the 10-mm hemispherical nodules was nearly equivalent at each site when 5 types of unsharp mask filter were used. The detection of the 5-mm nodules with mid-frequency suppressing and very-low-frequency enhancing filters was better than with a conventional (department standard) mid-frequency enhancing filter. Conclusion: Mid-frequency suppressing versions of the filter helped to demonstrate faint nodular opacity, which is often shown by early bronchogenic carcinoma. This filter could replace conventional filters in the detection of lung nodules.

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Digital signal processsing functions for ultra-low frequency calibrations

ACTA IMEKO ◽

10.21014/acta_imeko.v9i5.1004 ◽

2020 ◽

Vol 9 (5) ◽

pp. 374

Author(s):

Henrik Ingerslev ◽

Soren Andresen ◽

Jacob Holm Winther

Keyword(s):

Signal Processing ◽

Low Frequency ◽

Digital Signal ◽

Low Noise ◽

Key Comparison ◽

Low Frequencies ◽

Dual Channel ◽

Ultra Low Noise ◽

Lower Noise ◽

Better Than

The demand from industry to produce accurate acceleration measurements down to ever lower frequencies and with ever lower noise is increasing. Different vibration transducers are used today for many different purposes within this area, like detection and warning for earthquakes, detection of nuclear testing, and monitoring of the environment. Accelerometers for such purposes must be calibrated in order to yield trustworthy results and provide traceability to the SI-system accordingly. For these calibrations to be feasible, suitable ultra low-noise accelerometers and/or signal processing functions are needed. Here we present two digital signal processing (DSP) functions designed to measure ultra low-noise acceleration in calibration systems. The DSP functions use dual channel signal analysis on signals from two accelerometers measuring the same stimuli and use the coherence between the two signals to reduce noise. Simulations show that the two DSP functions are estimating calibration signals better than the standard analysis. The results presented here are intended to be used in key comparison studies of accelerometer calibration systems, and may help extend current general low frequency range from e.g. 100 mHz down to ultra-low frequencies of around 10mHz, possibly using somewhat same instrumentation.

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Seismic observations with broadband instruments at Santorini volcano

Bulletin of the Geological Society of Greece ◽

10.12681/bgsg.16844 ◽

2018 ◽

Vol 40 (3) ◽

pp. 1150 ◽

Cited By ~ 3

Author(s):

A. Kolaitis ◽

P. Papadimiriou ◽

I. Kassaras ◽

K. Makropoulos

Keyword(s):

Low Frequency ◽

Volcanic Tremor ◽

Velocity Model ◽

Dominant Frequency ◽

Depth Range ◽

Traveltime Inversion ◽

Time Frequency ◽

Inversion Procedure ◽

Santorini Volcano ◽

Better Than

Two arrays equipped with broadband sensors were installed for a period of 10 months, in order to study the seismic activity in the area of Santorini (Thira) volcano. During these periods, about 330 earthquakes were recorded and located within a radius of 50 km from the center of the caldera. An iterative damped traveltime inversion procedure yielded a local 1-D Ρ-wave velocity model and improved locations with an accuracy better than 5 Km in both horizontal and vertical components for 135 earthquakes. Those are mainly distributed within a depth range 5-18 Km, in the vicinity of the submarine Kolumbo Reef (NE of Santorini Island). Signal analysis of the recorded volcanic earthquakes including typical Fourier transformations and several operations in the time-frequency domain, allowed their dominant frequency determination and their classification into three groups based on waveform appearance and frequency content: (1) highfrequency events; (2) low-frequency events; and (3) volcanic tremor. Frequencytime analysis of tremor, detected at three stations, revealed two kinds of harmonic tremor with one sharp peak, at 3-5 Hz and 8.5-10 Hz.

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An Improved QIM Watermarking Algorithm

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.644-650.4641 ◽

2014 ◽

Vol 644-650 ◽

pp. 4641-4644

Author(s):

Zhen Xian Lin ◽

Yuan Sheng Li ◽

Jian Tao Li

Keyword(s):

Wavelet Transform ◽

High Frequency ◽

Low Frequency ◽

Test Results ◽

Quantization Method ◽

Lifting Wavelet Transform ◽

Watermark Embedding ◽

Lifting Wavelet ◽

Carrier Image ◽

Better Than

Put forward an improved QIM watermark embedding algorithm. The carrier image is transformed into YCbCr space, lifting wavelet transform the three components, then using the QIM quantization method embeds watermark into high frequency coefficients of Cb and Cr component, and Y component of low frequency coefficients. The experimental results show that embedded watermark which using improved algorithm has good invisibility. Anti attack test results show that after using common attack method attack the image embedded watermark, it can still extract the watermark completely. The anti-attack performance of improved QIM algorithm is much better than texture watermarking algorithm based on DCT.

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Layout Effects on High Frequency and Noise Parameters in MOSFETs

Indonesian Journal of Electrical Engineering and Computer Science ◽

10.11591/ijeecs.v6.i1.pp88-96 ◽

2017 ◽

Vol 6 (1) ◽

pp. 88

Author(s):

Asmaa Nur Aqilah Zainal Badri ◽

Norlaili Mohd Noh ◽

Shukri Bin Korakkottil Kunhi Mohd ◽

Asrulnizam Abd Manaf ◽

Arjuna Marzuki ◽

...

Keyword(s):

High Frequency ◽

Noise Figure ◽

Low Frequency ◽

Frequency Noise ◽

Noise Parameters ◽

Trench Isolation ◽

Gate Resistance ◽

The Impact ◽

Rf Noise ◽

Better Than

This study reviews related studies on the impact of the layout dependent effects on high frequency and RF noise parameter performances, carried out over the past decade. It specifically focuses on the doughnut and multi- finger layouts. The doughnut style involves the polygonal and the 4- sided techniques, while the multi-finger involving the narrow-oxide diffusion (OD) and multi-OD. The polygonal versus 4-sided doughnut, and the narrow-OD with multi-fingers versus multi-OD with multi- fingers are reviewed in this study. The high frequency parameters, which are of concern in this study, are the cut- off frequency (fT) and the maximum frequency (fMAX), whereas the noise parameters involved are noise resistance (RN) and the minimum noise figure (NFmin). In addition, MOSFET parameters, which are affected by the layout style that in turn may contribute to the changes in these high frequency, and noise parameters are also detailed. Such parameters include transconductance (Gm); gate resistance (Rg); effective mobility (μeff); and parasitic capacitances (cgg and cgd). Investigation by others has revealed that the polygonal doughnut may have a larger total area in comparison with the 4- sided doughnut. It is also found by means of this review that the multi-finger layout style with narrow-OD and high number of fingers may have the best performance in fT and fMAX, owing partly to the improvement in Gm, μeff, cgg, cgd and low frequency noise (LFN). A multi-OD with a lower number of fingers may lead to a lower performance in fT due to a lower Gm. Upon comparing the doughnut and the multi-finger layout styles, the doughnuts appeared to perform better than a standard multi-finger layout for fT, fMAX, Gm and μeff but are poorer in terms of LFN. It can then be concluded that the narrow-OD multi-finger may cause the increase of cgg as the transistor becomes narrower, whereas a multi-OD multi-finger may have high Rg and therefore may lead to the increase of fT and fMAX as the transistor becomes narrower. Besides, the doughnut layout style has a higher Gm and fT, leading to larger μeff from the elimination of shallow trench isolation (STI) stress.

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Low Frequency Calibration of Measurement Microphones

Noise Notes ◽

10.1260/1475-4738.9.2.55 ◽

2010 ◽

Vol 9 (2) ◽

pp. 55-60

Author(s):

Gunnar Rasmussen ◽

Kim Nielson

Keyword(s):

Low Frequency ◽

Frequency Calibration

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