scholarly journals Ultra-low frequency energy harvesting using bi-stability and rotary-translational motion in a magnet-tethered oscillator

2020 ◽  
Vol 101 (4) ◽  
pp. 2131-2143 ◽  
Author(s):  
Hailing Fu ◽  
Stephanos Theodossiades ◽  
Ben Gunn ◽  
Imad Abdallah ◽  
Eleni Chatzi
Keyword(s):  
Translational Motion ◽  
Low Frequency ◽  
Human Motion ◽  
Low Frequencies ◽  
Operation Conditions ◽  
Sensing Applications ◽  
Wide Range ◽  
Restoring Forces ◽  
Self Powered ◽  
Electromechanical Dynamics

Abstract Harvesting ultra-low frequency random vibration, such as human motion or turbine tower oscillations, has always been a challenge, but could enable many potential self-powered sensing applications. In this paper, a methodology to effectively harness this type of energy is proposed using rotary-translational motion and bi-stability. A sphere rolling magnet is designed to oscillate in a tube with two tethering magnets underneath the rolling path, providing two stable positions for the oscillating magnet. The generated magnetic restoring forces are of periodic form with regard to the sphere magnet location, providing unique nonlinear dynamics and allowing the harvester to operate effectively at ultra-low frequencies (< 1 Hz). Two sets of coils are mounted above the rolling path, and the change of magnetic flux within the coils accomplishes the energy conversion. A theoretical model, including the magnetic forces, the electromagnetic conversion and the occurring bi-stability, is established to understand the electromechanical dynamics and guide the harvester design. End linear springs are designed to maintain the periodic double-well oscillation when the excitation magnitude is high. Parametric studies considering different design factors and operation conditions are conducted to analyze the nonlinear electromechanical dynamics. The harvester illustrates its capabilities in effectively harnessing ultra-low frequency motions over a wide range of low excitation magnitudes.

scholarly journals A Two-Degree-of-Freedom Cantilever-Based Vibration Triboelectric Nanogenerator for Low-Frequency and Broadband Operation

Electronics ◽  
2019 ◽  
Vol 8 (12) ◽  
pp. 1526 ◽  
Author(s):  
Gang Tang ◽  
Fang Cheng ◽  
Xin Hu ◽  
Bo Huang ◽  
Bin Xu ◽  
...  
Keyword(s):  
Output Voltage ◽  
Low Frequency ◽  
Degree Of Freedom ◽  
Triboelectric Nanogenerator ◽  
Energy Harvesters ◽  
Harvesting Technique ◽  
Wide Range ◽  
Operating Bandwidth ◽  
Self Powered ◽  
Two Degree Of Freedom

With the continual increasing application requirements of broadband vibration energy harvesters (VEHs), many attempts have been made to broaden the bandwidth. As compared to adopted only a single approach, integration of multi-approaches can further widen the operating bandwidth. Here, a novel two-degree-of-freedom cantilever-based vibration triboelectric nanogenerator is proposed to obtain high operating bandwidth by integrating multimodal harvesting technique and inherent nonlinearity broadening behavior due to vibration contact between triboelectric surfaces. A wide operating bandwidth of 32.9 Hz is observed even at a low acceleration of 0.6 g. Meanwhile, the peak output voltage is 18.8 V at the primary resonant frequency of 23 Hz and 1 g, while the output voltage is 14.9 V at the secondary frequency of 75 Hz and 2.5 g. Under the frequencies of these two modes at 1 g, maximum peak power of 43.08 μW and 12.5 μW are achieved, respectively. Additionally, the fabricated device shows good stability, reaching and maintaining its voltage at 8 V when tested on a vacuum compression pump. The experimental results demonstrate the device has the ability to harvest energy from a wide range of low-frequency (<100 Hz) vibrations and has broad application prospects in self-powered electronic devices and systems.

PIV Analysis of Dynamic Velocity Profiles in Non-Newtonian Drilling Fluids Exposed to Oscillatory Motion

2018 ◽  
Author(s):  
Maduranga Amaratunga ◽  
Roar Nybø ◽  
Rune W. Time
Keyword(s):  
Low Frequency ◽  
Velocity Profiles ◽  
Liquid Column ◽  
Oscillatory Motion ◽  
Velocity Shear ◽  
Drilling Fluids ◽  
Cross Sectional ◽  
Low Frequencies ◽  
Wide Range ◽  
Dynamic Velocity

Drilling fluids experience a wide range of shear rates and oscillatory motion while circulating through the well and also during the operations for solids control. Therefore, it is important to investigate the influence of oscillatory fields on the velocity profiles, shear rate and resulting rheological condition of non-Newtonian polymers, which are additives in drilling fluids. In this paper, we present the dynamic velocity profiles within both Newtonian (deionized water) and non-Newtonian liquids (Polyanionic Cellulose – PAC) exposed to oscillatory motion. A 15 cm × 15 cm square cross-sectional liquid column was oscillated horizontally with very low frequencies (0.75–1.75 Hz) using a laboratory made oscillating table. The dynamic velocity profiles at the bulk of the oscillating liquid column were visualized by the Particle Image Velocimetry (PIV) method, where the motion of fluid is optically visualized using light scattering “seeding” particles. Increased frequency of oscillations lead to different dynamic patterns and ranges of velocity-shear magnitudes. The experiments are part of a comprehensive study aimed at investigating the influence of low frequency oscillations on particle settling in non-Newtonian drilling fluids. It is discussed, how such motion imposed on polymeric liquids influences both flow dynamics as well as local settling velocities of cuttings particles.

scholarly journals Portable Mobile Gait Monitor System Based on Triboelectric Nanogenerator for Monitoring Gait and Powering Electronics

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4996
Author(s):  
Yupeng Mao ◽  
Yongsheng Zhu ◽  
Tianming Zhao ◽  
Changjun Jia ◽  
Xiao Wang ◽  
...  
Keyword(s):  
Electronic Device ◽  
Low Frequency ◽  
Aluminum Foil ◽  
Development Trend ◽  
Human Motion ◽  
Triboelectric Nanogenerator ◽  
Portable Devices ◽  
Voltage Output ◽  
Self Powered ◽  
Triboelectric Effect

A self-powered portable triboelectric nanogenerator (TENG) is used to collect biomechanical energy and monitor the human motion, which is the new development trend in portable devices. We have developed a self-powered portable triboelectric nanogenerator, which is used in human motion energy collection and monitoring mobile gait and stability capability. The materials involved are common PTFE and aluminum foil, acting as a frictional layer, which can output electrical signals based on the triboelectric effect. Moreover, 3D printing technology is used to build the optimized structure of the nanogenerator, which has significantly improved its performance. TENG is conveniently integrated with commercial sport shoes, monitoring the gait and stability of multiple human motions, being strategically placed at the immediate point of motion during the respective process. The presented equipment uses a low-frequency stabilized voltage output system to provide power for the wearable miniature electronic device, while stabilizing the voltage output, in order to effectively prevent voltage overload. The interdisciplinary research has provided more application prospects for nanogenerators regarding self-powered module device integration.

scholarly journals Assessment of the Effects of Superior Canal Dehiscence Location and Size on Intracochlear Sound Pressures

2014 ◽  
Vol 20 (1) ◽  
pp. 62-71 ◽  
Author(s):  
Marlien E.F. Niesten ◽  
Christof Stieger ◽  
Daniel J. Lee ◽  
Julie P. Merchant ◽  
Wilko Grolman ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Temporal Bone ◽  
Semicircular Canal ◽  
Low Frequency ◽  
Low Frequencies ◽  
Superior Canal Dehiscence ◽  
Superior Semicircular Canal ◽  
Wide Range ◽  
Before And After ◽  
Canal Dehiscence

Superior canal dehiscence (SCD) is a defect in the bony covering of the superior semicircular canal. Patients with SCD present with a wide range of symptoms, including hearing loss, yet it is unknown whether hearing is affected by parameters such as the location of the SCD. Our previous human cadaveric temporal bone study, utilizing intracochlear pressure measurements, generally showed that an increase in dehiscence size caused a low-frequency monotonic decrease in the cochlear drive across the partition, consistent with increased hearing loss. This previous study was limited to SCD sizes including and smaller than 2 mm long and 0.7 mm wide. However, the effects of larger SCDs (>2 mm long) were not studied, although larger SCDs are seen in many patients. Therefore, to answer the effect of parameters that have not been studied, this present study assessed the effect of SCD location and the effect of large-sized SCDs (>2 mm long) on intracochlear pressures. We used simultaneous measurements of sound pressures in the scala vestibuli and scala tympani at the base of the cochlea to determine the sound pressure difference across the cochlear partition - a measure of the cochlear drive in a temporal bone preparation - allowing for assessment of hearing loss. We measured the cochlear drive before and after SCDs were made at different locations (e.g. closer to the ampulla of the superior semicircular canal or closer to the common crus) and for different dehiscence sizes (including larger than 2 mm long and 0.7 mm wide). Our measurements suggest the following: (1) different SCD locations result in similar cochlear drive and (2) larger SCDs produce larger decreases in cochlear drive at low frequencies. However, the effect of SCD size seems to saturate as the size increases above 2-3 mm long and 0.7 mm wide. Although the monotonic effect was generally consistent across ears, the quantitative amount of change in cochlear drive due to dehiscence size varied across ears. Additionally, the size of the dehiscence above which the effect on hearing saturated varied across ears. These findings show that the location of the SCD does not generally influence the amount of hearing loss and that SCD size can help explain some of the variability of hearing loss in patients. i 2014 S. Karger AG, Basel

scholarly journals Millisecond pulsars at low frequencies

2017 ◽  
Vol 13 (S337) ◽  
pp. 311-312
Author(s):  
N. D. Ramesh Bhat ◽  
Steven E. Tremblay ◽  
Franz Kirsten
Keyword(s):  
South African ◽  
Southern Hemisphere ◽  
Low Frequency ◽  
Pulsar Emission ◽  
Millisecond Pulsars ◽  
Low Frequencies ◽  
Pulsar Timing ◽  
Wide Range ◽  
Propagation Effects ◽  
Murchison Widefield Array

AbstractLow-frequency pulsar observations are well suited for studying propagation effects caused by the interstellar medium (ISM). This is particularly important for millisecond pulsars (MSPs) that are part of high-precision timing applications such as pulsar timing arrays (PTA), which aim to detect nanoHertz gravitational waves. MSPs in the southern hemisphere will also be the prime targets for PTAs with the South African MeerKAT, and eventually with the SKA. The development of the Murchison Widefield Array (MWA) and the Engineering Development Array (EDA) brings excellent opportunities for low-frequency studies of MSPs in the southern hemisphere. They enable observations at frequencies from 50 MHz to 300 MHz, and can be exploited for a wide range of studies relating to pulsar emission physics and probing the ISM.

Threshold Firing Frequency–Current Relationships of Neurons in Rat Somatosensory Cortex: Type 1 and Type 2 Dynamics

2004 ◽  
Vol 92 (4) ◽  
pp. 2283-2294 ◽  
Author(s):  
T. Tateno ◽  
A. Harsch ◽  
H. P. C. Robinson
Keyword(s):  
Somatosensory Cortex ◽  
Low Frequency ◽  
Firing Frequency ◽  
Spike Generation ◽  
Low Frequencies ◽  
Subthreshold Oscillations ◽  
Wide Range ◽  
Rat Somatosensory Cortex

Neurons and dynamical models of spike generation display two different types of threshold behavior, with steady current stimulation: type 1 [the firing frequency vs. current ( f– I) relationship is continuous at threshold) and type 2 (discontinuous f– I)]. The dynamics at threshold can have profound effects on the encoding of input as spikes, the sensitivity of spike generation to input noise, and the coherence of population firing. We have examined the f– I and frequency–conductance ( f– g) relationships of cells in layer 2/3 of slices of young (15–21 DIV) rat somatosensory cortex, focusing in detail on the nature of the threshold. Using white-noise stimulation, we also measured firing frequency and interspike interval variability as a function of noise amplitude. Regular-spiking (RS) pyramidal neurons show a type 1 threshold, consistent with their well-known ability to fire regularly at very low frequencies. In fast-spiking (FS) inhibitory interneurons, although regular firing is supported over a wide range of frequencies, there is a clear discontinuity in their f– I relationship at threshold (type 2), which has not previously been highlighted. FS neurons are unable to support maintained periodic firing below a critical frequency fc, in the range of 10 to 30 Hz. Very close to threshold, FS cells switch irregularly between bursts of periodic firing and subthreshold oscillations. These characteristics mean that the dynamics of RS neurons are well suited to encoding inputs into low-frequency firing rates, whereas the dynamics of FS neurons are suited to maintaining and quickly synchronizing to gamma and higher-frequency input.

Vehicle motion and motion sickness in pigs

1998 ◽  
Vol 66 (1) ◽  
pp. 239-245 ◽  
Author(s):  
J. M. Randall ◽  
R. H. Bradshaw
Keyword(s):  
Motion Sickness ◽  
Predictive Models ◽  
Low Frequency ◽  
Vertical Axis ◽  
Human Motion ◽  
Human Model ◽  
Road Vehicles ◽  
Low Frequencies ◽  
Vehicle Motion ◽  
Motion Characteristics

AbstractLow frequency oscillatory motion (0·05 to 0·5 Hz) experienced in ships and road vehicles is known to cause motion sickness in humans and some predictive models are available. There have been very few studies of the incidence of motion sickness in pigs and none which has attempted to identify the frequencies of motion of transporters which are likely to be implicated. In this study, the vibration and motion characteristics of a commercial pig transporter were measured while seven individually penned 40-kg pigs were transported for short (100 min) journeys and 80-kg pigs penned in groups of 12 or 13 were transported for longer (4·5 h) journeys. Direct behavioural observations were made of individual pigs for symptoms of travel sickness (sniffing, foaming at the mouth, chomping, and retching or vomiting). A comparison was then made between the incidence of travel sickness in pigs and that expected in humans given the measured vehicle vibration characteristics. The low frequencies of motion measured on the transporter (0·01 to 0·2 Hz) were well within the range implicated in human motion sickness with considerable power in the longitudinal and lateral axes but little in the vertical axis. On both short and long journeys pigs exhibited symptoms of travel sickness. The likely incidence of travel sickness on the short journeys predicted by the human model was 24 to 31% which corresponds to approximately two of the seven 40-kg pigs becoming travel sick. The numbers observed were generally lower than this although the same pigs were transported twice each day for 2 days and this may have therefore reflected the effects of habituation. The incidence of travel sickness on the long journeys predicted by the human model was 34%. During these journeys which involved four groups of 80-kg pigs which were not repeatedly transported, 26% of pigs vomited or retched (13 out of 50) while 50% showed advanced symptoms of foaming and chomping. These results are not inconsistent with the human model which should form the basis offurther research.

scholarly journals Polyaniline/Polystyrene Blends: In-Depth Analysis of the Effect of Sulfonic Acid Dopant Concentration on AC Conductivity Using Broadband Dielectric Spectroscopy

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Noora Al-Thani ◽  
Mohammad K. Hassan ◽  
Jolly Bhadra
Keyword(s):  
Dielectric Spectroscopy ◽  
Ac Conductivity ◽  
Sulfonic Acid ◽  
Low Frequency ◽  
Lone Pair ◽  
Interfacial Polarization ◽  
Low Frequencies ◽  
Broadband Dielectric Spectroscopy ◽  
Wide Range ◽  
Depth Analysis

This work presents an in-depth analysis of the alternating current (AC) conductivity of polyaniline-polystyrene (PANI-PS) blends doped with camphor sulfonic acid (CSA) and prepared using an in situ dispersion polymerization technique. We prepared the blends using fixed ratios of PS to PANI while varying the concentration of the CSA dopant. The AC conductivity of the blends was investigated using broadband dielectric spectroscopy. Increasing CSA resulted in a decrease in the AC conductivity of the blends. This behaviour was explained in terms of the availability of a lone pair of electrons of the NH groups in the polyaniline, which are typically attacked by the electron-withdrawing sulfonic acid groups of CSA. The conductivity is discussed in terms of changes in the dielectric permittivity storage (ε′), loss (ε′′), and modulus (M′′) of the blends over a wide range of temperatures. This is linked to the glass transition temperature of the PANI. Dielectric spectra at low frequencies indicated the presence of pronounced Maxwell-Wagner-Sillars (MWS) interfacial polarization, especially in samples with a low concentration of CSA. Electrical conduction activation energies for the blends were also calculated using the temperature dependence of the direct current (DC) conductivity at a low frequency (σdc), which exhibit an Arrhenius behaviour with respect to temperature. Scanning electron microscopy revealed a fibrous morphology for the pure PANI, while the blends showed agglomeration with increasing CSA concentrations.

Coupling of sympathetic nerve traffic and BP at very low frequencies is mediated by large-amplitude events

2003 ◽  
Vol 284 (3) ◽  
pp. R802-R810 ◽  
Author(s):  
Don E. Burgess ◽  
David C. Randall ◽  
Richard O. Speakman ◽  
David R. Brown
Keyword(s):  
Sympathetic Nerve ◽  
Wavelet Transforms ◽  
Large Amplitude ◽  
Low Frequency ◽  
Functional Connection ◽  
Low Frequencies ◽  
Very Low Frequency ◽  
Arterial Blood ◽  
Wide Range ◽  
Transient Events

This study explores the functional association between renal sympathetic nerve traffic (NT) and arterial blood pressure (BP) in the very-low-frequency range (i.e., <0.1 Hz). NT and BP ( n = 6) or BP alone ( n = 17) was recorded in unanesthetized rats ( n = 6). Data were collected for 2–5 h, and wavelet transforms were calculated from data epochs of up to 1 h. From these transforms, we obtained probability distributions for fluctuation amplitudes over a range of time scales. We also computed the cross-wavelet power spectrum between NT and BP to detect the occurrence in time of large-amplitude transient events that may be important in the autonomic regulation of BP. Finally, we computed a time sequence of cross correlations between NT and BP to follow the relationship between NT and BP in time. We found that NT and BP follow comparable self-similar scaling relationships (i.e., NT and BP fluctuations exhibit a certain type of power law behavior). Scaling of this nature 1) points to underlying dynamics over a wide range of scales and 2) is related to large-amplitude events that contribute to the very-low-frequency variability of NT and BP. There is a strong correlation between NT and BP during many of these transient events. These strong correlations and the uniformity in scaling imply a functional connection between these two signals at frequencies where we previously found no connection using spectral coherence.

scholarly journals The Astronomical Low-Frequency Array (ALFA)

1998 ◽  
Vol 164 ◽  
pp. 393-394 ◽  
Author(s):  
D. L. Jones ◽  
K. W. Weiler ◽  
R. J. Allen ◽  
M. M. Desch ◽  
W. C. Erickson ◽  
...  
Keyword(s):  
High Resolution ◽  
Solar System ◽  
Angular Resolution ◽  
Low Frequency ◽  
Low Frequencies ◽  
Wide Range ◽  
High Resolution Images ◽  
Coherent Emission ◽  
Age Of The Universe ◽  
The Universe

AbstractThe ALFA mission is designed to map the entire sky at frequencies between approximately 0.3 and 30 MHz with angular resolution limited by interstellar and interplanetary scattering. Most of this region of the spectrum is inaccessible from the ground because of absorption and refraction by the Earth’s ionosphere. A wide range of astrophysical questions concerning solar system, galactic, and extragalactic objects could be answered with high resolution images at low frequencies, where absorption effects and coherent emission processes become important and the synchrotron lifetimes of electrons are comparable to the age of the universe.

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