The Motion of Strawberry Leaves in an Air-Assisted Spray Field and its Influence on Droplet Deposition

2021 ◽  
Vol 64 (1) ◽  
pp. 83-93
Author(s):  
Shuo Wu ◽  
Jizhan Liu ◽  
Jiangshan Wang ◽  
Dianhe Hao ◽  
Rongkai Wang
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
High Amplitude ◽  
Azimuth Angle ◽  
List Type ◽  
Droplet Deposition ◽  
Inclination Angles ◽  
Turbulence Effect ◽  
Spray Field ◽  
Low Amplitude

HighlightsA visualization method for the motion of strawberry leaves in an air-assisted spray field is proposed.Strawberry leaves showed two motion states in different critical velocity ranges of the sprayer airflow.The airflow instability and the turbulence effect are considered important factors for the leaf vibrations.A strawberry leaf azimuth angle in the range of 90° to 270° can provide good deposition with smaller droplets.Abstract. The reasonable motion of crop plants in an air-assisted spray field can improve droplet deposition. Therefore, this study focuses on the motion of strawberry leaves and the droplet deposition mechanism in an air-assisted spray field. First, this study proposes a descriptive method for strawberry leaf motion in an air-assisted spray field and clarifies the important influence of strawberry leaf motion on droplet deposition. Second, an experiment was performed on the motion and droplet capture of single strawberry leaves in multi-position postures in an air-assisted spray field. The results showed that the leaves had two motion states (i.e., low amplitude with low frequency and high amplitude with high frequency) at different airflow velocities and inclination angles, and the critical airflow velocity corresponding to the two motion states was determined to be 8.7 m s-1. When the azimuth angle of the strawberry leaves is in the range of 90° to 270°, a reasonable inclination angle of the airflow and the high frequency and high amplitude vibration state of the leaves driven by the airflow will provide good deposition and canopy penetration of droplets with smaller diameters. Keywords: Air-assisted spray field, Droplet deposition, Motion, Spray, Strawberry leaves.

scholarly journals Mechanistic Characteristics of Double Dominant Frequencies of Acoustic Emission Signals in the Entire Fracture Process of Fine Sandstone

Energies ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3959 ◽  
Author(s):  
Chuangye Wang ◽  
Xinke Chang ◽  
Yilin Liu ◽  
Shijiang Chen
Keyword(s):  
Frequency Band ◽  
High Frequency ◽  
Fracture Process ◽  
Low Frequency ◽  
High Amplitude ◽  
Dominant Frequency ◽  
Band Energy ◽  
Ae Signal ◽  
Low Amplitude ◽  
Frequency Band Energy

To determine the intrinsic relationship between the acoustic emission (AE) phenomenon and the fracture pattern pertaining to the entire fracture process of rock, the present paper proposed a multi-dimensional spectral analysis of the AE signal released during the entire process. Some uniaxial compression AE tests were carried out on the fine sandstone specimens, and the axial compression stress–strain curves and AE signal released during the entire fracture process were obtained. In order to deal with tens of thousands of AE data efficiently, a subroutine was programmed in MATLAB. All AE waveforms of the tests were denoised by wavelet threshold firstly. The fast Fourier transform (FFT) and wavelet packet transform (WPT) were applied to the denoised waveforms to obtain the dominant frequency, amplitude, fractal, and frequency band energy ratio distribution. The results showed that the AE signal in the entire fracture process of fine sandstone had a double dominant frequency band of the low and high-frequency bands, which can be subdivided into low-frequency low-amplitude, high-frequency low-amplitude, high-frequency high-amplitude, and low-frequency high-amplitude signals, according to the magnitude. The low-frequency amplitude relevant fractal dimension and the high-frequency amplitude relevant fractal dimension each had turning points that corresponded to significant decreases in the middle and end stages of loading, respectively. The frequency band energy was mainly concentrated in the range of 0–187.5 kHz, and the energy ratios of some bands had different turning points, which appeared before the complete failure of the rock. It is suggested that the multi-dimensional spectral analysis may understand the failure mechanism of rock better.

An Experimental Investigation of Energy Transfer from a High- Frequency Mode to a Low-Frequency Mode in a Flexible Structure

1995 ◽  
Vol 1 (1) ◽  
pp. 115-128 ◽  
Author(s):  
Pavol Popovic ◽  
Ali H. Nayfeh ◽  
Kyoyul Oh ◽  
Samir A. Nayfeh
Keyword(s):  
Energy Transfer ◽  
High Frequency ◽  
Power Spectra ◽  
Low Frequency ◽  
Excitation Amplitude ◽  
High Amplitude ◽  
Frequency Mode ◽  
High Frequency Mode ◽  
Beam Frame ◽  
Low Amplitude

The objective of the present article is to experimentally observe and characterize the transfer of energy from low-amplitude, high-frequency modes to high-amplitude, low-frequency modes. The subject of the study is a three-beam frame. The excitation amplitude is restricted to below 2 g peak. The authors have focused on observing, characterizing, and documenting the excitation of the first mode by high-frequency forcing. The energy-transfer processes are identified by power spectra and characterized further by frequency and amplitude sweeps. The energy-transfer routes observed in the experiment are subharmonic resonance of order one-half, combination resonance of the additive type, and interaction between widely spaced modes. In the latter route, an excitation at a frequency that is more than 100 times the first-mode frequency has been observed to excite the first mode.

Design of a Retrofittable Spindle Attachment for High Frequency Vibration-Assisted Drilling

2014 ◽  
Author(s):  
J. Panju ◽  
M. Meshreki ◽  
M. H. Attia
Keyword(s):  
High Frequency ◽  
High Speed ◽  
Low Frequency ◽  
Cutting Parameters ◽  
High Amplitude ◽  
Spindle Attachment ◽  
Vibration Assistance ◽  
Low Amplitude ◽  
Thrust Forces ◽  
Conventional Drilling

Conventional drilling of modern super alloys and composite material induces high stresses in the vicinity of drilled holes along with high thrust forces which lead to problems in terms of hole quality and accuracy as well as increased tool wear. A recent and promising technique to overcome these challenges is to introduce vibration assistance in the cutting zone by superimposing oscillating vibration in the feed direction of the tool. Two regimes of vibration excitation could be applied for this purpose: low frequency (<500 Hz) high amplitude (>100 μm) and high frequency (>500 Hz) low amplitude (<20 μm). Motivated by the advantages of the HF-VAD and the limited work available in the literature for this regime, a new system is developed by the authors where the rotating tool is excited to high frequency and low amplitude. The new design is based on the use of piezoelectric actuators to generate the motion and a high speed slip ring to ensure the transfer of sufficient power to the actuator. A novel concept was implemented by de-coupling the rotary motion of the spindle from the vibrational motion of the actuator to ensure a higher efficiency of power transmission without damaging either the actuator or the spindle. With this design, a retrofittable HSK 100A toolholder with high frequency excitation spindle attachment was manufactured to incorporate drill sizes up to 1/4 inches. Commissioning tests were performed under no load and spring loaded conditions and it was found that the system has a capability to excite the tool up to 100 μm at 900 Hz (resonance frequency) and up to 5 μm between 500–800 Hz and 1100–2500 Hz. HF-VAD tests were conducted using this new attachment on Aluminum 6061 and it was found that the system was able to successfully obtain the prescribed frequency and amplitude. Up to 50% reduction in thrust forces was obtained in HF-VAD in comparison to conventional drilling under same cutting parameters; this is associated with finer chips with break off serrations.

SEISMIC STRATIGRAPHIC EVALUATION OF A NEOCOMIAN SUBMARINE FAN SYSTEM, BROWSE BASIN, NORTH WEST SHELF

1992 ◽  
Vol 32 (1) ◽  
pp. 171
Author(s):  
L.R. Miller ◽  
W.J. Stuart
Keyword(s):  
High Frequency ◽  
Seismic Reflection ◽  
Low Frequency ◽  
High Amplitude ◽  
Seismic Facies ◽  
Submarine Fan ◽  
North West ◽  
The North ◽  
Braided Channel ◽  
Low Amplitude

A possible submarine fan system of Valanginian age occurs in the south of the western half of Permit WA-212-P in the Browse Basin. Seismic mapping and interpretation have allowed the recognition of five seismic facies which are considered representative of this fan system.The five seismic facies are the upper-middle fan braided channel facies, the upper-middle fan braided interchannel facies, the lower fan channel facies, the lower fan sheet facies, and the lower fan lobe fringe facies. The reflections of the upper-middle braided channel fan facies are discontinuous, disrupted, convex up, low amplitude and high frequency. The interchannel facies has reflections that are concave up, continuous, low frequency and moderate to high amplitude. The lower fan channel facies are recognised by convex up, discontinuous, high frequency and low amplitude reflections. The lower fan sheet facies is noted by mounded configurations with continuous, moderate to high amplitude, moderate frequency reflections. The lower fan lobe fringe facies reflections are flat, often shingled reflections with moderate discontinuity, moderate to high amplitude and low to moderate frequency.Since no wells penetrate the submarine fan, the interpretation is based on seismic reflection configurations which are considered typical of submarine fan segments. The interpreted ancient submarine fan occurs on the basin floor adjacent to a probable ramp type margin, and manifests shape and setting consistent with known submarine fans, such as the Eocene Frigg Fan of the North Sea, and the Lower Cretaceous Barrow Group turbidites in the Carnarvon Basin.Seismic facies mapping, in conjunction with sequence stratigraphy concepts, is particularly useful in areas such as the Browse Basin where considerable marine shale sections exist with little structure, and sequences with reservoir potential continue to be a problem to locate. For instance, in Caswell-1, a well drilled in 1977 immediately north of the permit area, 200 barrels of oil flowed from thin sands within a shale sequence of Albian age. Results of this study indicate that local seismic reflection signatures may be indicative of potential sandstone reservoirs in the vicinity of the study area.

Frequency Response Analysis of Piecewise Nonlinear Vibration Isolator

2005 ◽  
Author(s):  
Patrick Stahl ◽  
G. Nakhaie Jazar
Keyword(s):  
Low Frequency ◽  
High Amplitude ◽  
Relative Displacement ◽  
Response Analysis ◽  
Frequency Response Analysis ◽  
State Behavior ◽  
Vibration Isolators ◽  
Short Period ◽  
Secondary Suspension ◽  
Low Amplitude

Non-smooth piecewise functional isolators are smart passive vibration isolators that can provide effective isolation for high frequency/low amplitude excitation by introducing a soft primary suspension, and by preventing a high relative displacement in low frequency/high amplitude excitation by introducing a relatively damped secondary suspension. In this investigation a linear secondary suspension is attached to a nonlinear primary suspension. The primary is assumed to be nonlinear to model the inherent nonlinearities involved in real suspensions. However, the secondary suspension comes into action only during a short period of time, and in mall domain around resonance. Therefore, a linear assumption for the secondary suspension is reasonable. The dynamic behavior of the system subject to a harmonic base excitation has been analyzed utilizing the analytic results derived by applying the averaging method. The analytic results match very well in the transition between the two suspensions. A sensitivity analysis has shown the effect of varying dynamic parameters in the steady state behavior of the system.

Oxygen Consumption by the Sea Anemone Calliactis Parasitica (Couch)

1980 ◽  
Vol 88 (1) ◽  
pp. 367-374
Author(s):  
A. E. BRAFIELD
Keyword(s):  
Oxygen Consumption ◽  
Oxygen Concentration ◽  
Low Frequency ◽  
High Amplitude ◽  
Total Oxygen ◽  
Strip Chart ◽  
Calliactis Parasitica ◽  
Cycle Lengths ◽  
Mean Cycle ◽  
Low Amplitude

Oxygen consumption by Calliactis parasitica, measured in a continuousflow polarographic respirometer, yielded a slope of 0·92 when plotted against body weight on log scales. This high value is discussed in terms of the sea anemone's basically laminate nature. Strip-chart records of the oxygen concentration of water which had just passed a specimen of Calliactis commonly showed rhythmic fluctuations, either of low amplitude and high frequency or high amplitude and low frequency (mean cycle lengths 11 and 34 min respectively). The fluctuations are explained in terms of rhythmic muscular contractions which irrigate the enteron for respiratory purposes. Analysis of the slow fluctuations indicates that the endoderm is responsible for about 18% of the total oxygen consumption. The oxygen concentration of water in the enteron, measured and recorded continuously, was 4–27% of the air-saturation level. These strip chart records also frequently showed rhythmic fluctuations (mean cycle length 12 min), apparently resulting from the muscular contractions.

Electrical Resistive Spiking of Fungi

2021 ◽  
pp. 1-7 ◽  
Author(s):  
Andrew Adamatzky ◽  
Alessandro Chiolerio ◽  
Georgios Sirakoulis
Keyword(s):  
Electrical Resistance ◽  
Electronic Devices ◽  
Low Frequency ◽  
High Amplitude ◽  
Average Amplitude ◽  
Average Width ◽  
C 23 ◽  
C 30 ◽  
Low Amplitude

We study long-term electrical resistance dynamics in mycelium and fruit bodies of oyster fungi P. ostreatus. A nearly homogeneous sheet of mycelium on the surface of a growth substrate exhibits trains of resistance spikes. The average width of spikes is c. 23[Formula: see text]min and the average amplitude is c. 1[Formula: see text]k[Formula: see text]. The distance between neighboring spikes in a train of spikes is c. 30[Formula: see text]min. Typically, there are 4–6 spikes in a train of spikes. Two types of electrical resistance spikes trains are found in fruit bodies: low frequency and high amplitude (28[Formula: see text]min spike width, 1.6[Formula: see text]k[Formula: see text] amplitude, 57[Formula: see text]min distance between spikes) and high frequency and low amplitude (10[Formula: see text]min width, 0.6[Formula: see text]k[Formula: see text] amplitude, 44[Formula: see text]min distance between spikes). The findings could be applied in monitoring of physiological states of fungi and future development of living electronic devices and sensors.

Follicle size and reproductive hormone profiles during a post-weaning altrenogest treatment in primiparous sows

2015 ◽  
Vol 27 (2) ◽  
pp. 304 ◽  
Author(s):  
J. J. J. van Leeuwen ◽  
M. R. T. M. Martens ◽  
J. Jourquin ◽  
M. A. Driancourt ◽  
A. Wagner ◽  
...  
Keyword(s):  
High Frequency ◽  
Fold Increase ◽  
High Amplitude ◽  
Daily Administration ◽  
Reproductive Hormone ◽  
Diurnal Pattern ◽  
Once Daily ◽  
Follicular Wave ◽  
Follicle Size ◽  
Low Amplitude

This study investigated the endocrine background of follicle size changes during post-weaning altrenogest treatment. altrenogest-treated sows received a 20-mg dosage daily at 8.00 a.m. from Day –1 to Day 14 after weaning. On Day –1, only 3/13 altrenogest-treated sows showed LH pulses compared with 8/8 control sows (P = 0.001). On Day 0, control sows showed a typical high frequency–low amplitude LH pattern, indicative for recruitment of oestrogenic follicles. In altrenogest-treated animals on Day 0, half of the sows showed high frequency–high amplitude pulses from 4–5 h after weaning. In altrenogest-treated sows, average follicle size increased from 3.1 ± 0.5 mm on Day 0 to 4.4 ± 0.6 mm on Day 5, then decreased to 3.7 ± 0.5 mm on Day 7 and stabilised thereafter. FSH and oestradiol (E2) concentrations showed a distinct diurnal pattern; high at 7.00 a.m. and low at 3.00 p.m. E2 concentrations (7.00 a.m.) showed a 2.5-fold increase from Day –1 to Day 2, and subsequently a 2-fold decline to reach a plateau at Day 8. FSH concentrations reached maximum levels by Day 5 and slowly declined afterwards. In conclusion, once-daily administration of altrenogest starting one day before weaning delays the weaning-induced increase in LH pulses. Although FSH and follicle size increase until Day 5 after weaning, follicle E2 production already decreased from Day 2 after weaning. Post-weaning altrenogest treatment thus results in a follicular wave of follicles that lose oestrogenic competence at Day 2 after weaning, presumably related to the changed LH dynamics during altrenogest treatment.

Vibrational Fatigue Analysis of a Strain Loading Using the Frequency and Wavelet Filtering Methods

2011 ◽  
Vol 462-463 ◽  
pp. 124-129
Author(s):  
Shahrum Abdullah ◽  
Edisah Putra Teuku ◽  
Zaki Nuawi Mohd. ◽  
Mohd. Nopiah Zulkifli
Keyword(s):  
High Frequency ◽  
Filter Design ◽  
High Amplitude ◽  
Morlet Wavelet ◽  
Wavelet Filtering ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Automotive Components ◽  
Low Pass ◽  
Low Amplitude

This paper presents a comparison work between the filtering methods of fatigue strain loadings using the frequency spectrum and the wavelet transform (WT), in which a raw loading signal can be simplified for purpose of simulation. For this reason, the Fast Fourier Transform (FFT) and the Morlet wavelet algorithms were used in order to transform the vibrational fatigue time series into the frequency domain signal, leading to the observation of the frequency characteristics of the signal. To retain high amplitude cycles in the FFT algorithm, a low pass filter technique was applied to remove the high frequency signals with small amplitude that are non-damaging. The departure of high frequency information smoothed the low amplitude cycles at high frequency events in the fatigue signal. The Butterworth filter was selected as the most efficient filter design as it retained most of the fatigue damage and also had the capability to remove 30 % of the original low amplitude cycles. On the other hand, the Morlet wavelet managed to remove 64 % of the original 59 second signal. This wavelet filtering method removed 34 % more than the similar procedure applied through the FFT approach. Hence, this fatigue data summarising algorithm can be used for studying the durability characteristics of automotive components.

scholarly journals Brain oscillations and connectivity in autism spectrum disorders (ASD): new approaches to methodology, measurement and modelling

2016 ◽  
Author(s):  
K. Kessler ◽  
R. A. Seymour ◽  
G. Rippon
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Autism Spectrum ◽  
List Type ◽  
Brain Oscillations ◽  
New Techniques ◽  
Low Frequencies ◽  
High Frequency Activity ◽  
Recent Classification ◽  
The Brain

AbstractAlthough atypical social behaviour remains a key characterisation of ASD, the presence of sensory and perceptual abnormalities has been given a more central role in recent classification changes. An understanding of the origins of such aberrations could thus prove a fruitful focus for ASD research. Early neurocognitive models of ASD suggested that the study of high frequency activity in the brain as a measure of cortical connectivity might provide the key to understanding the neural correlates of sensory and perceptual deviations in ASD. As our review shows, the findings from subsequent research have been inconsistent, with a lack of agreement about the nature of any high frequency disturbances in ASD brains. Based on the application of new techniques using more sophisticated measures of brain synchronisation, direction of information flow, and invoking the coupling between high and low frequency bands, we propose a framework which could reconcile apparently conflicting findings in this area and would be consistent both with emerging neurocognitive models of autism and with the heterogeneity of the condition.HighlightsSensory and perceptual aberrations are becoming a core feature of the ASD symptom prolife.Brain oscillations and functional connectivity are consistently affected in ASD.Relationships (coupling) between high and low frequencies are also deficient.Novel framework proposes the ASD brain is marked by local dysregulation and reduced top-down connectivityThe ASD brain’s ability to predict stimuli and events in the environment may be affectedThis may underlie perceptual sensitives and cascade into social processing deficits in ASD

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