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.

The Respiration of Pteroides Griseum (Bohadsch) a Pennatulid Coelenterate

1967 ◽  
Vol 46 (1) ◽  
pp. 97-104
Author(s):  
A. E. BRAFIELD ◽  
G. CHAPMAN
Keyword(s):  
Body Weight ◽  
Oxygen Consumption ◽  
Oxygen Concentration ◽  
Continuous Flow ◽  
Strip Chart Recorder ◽  
Total Oxygen ◽  
Strip Chart ◽  
Chart Recorder ◽  
Rate Of Oxygen Consumption ◽  
Exponential Relation

1. The respiration of the pennatulid Pteroides griseum has been investigated by means of a continuous-flow polarographic respirometer and a strip-chart recorder. 2. The rate of oxygen consumption bears the same exponential relation to body weight as in more advanced phyla, and is markedly greater in expanded specimens than in contracted ones. 3. It is suggested that contracted specimens consume oxygen almost exclusively through the ectoderm but that in expanded specimens at least two-thirds of the total oxygen consumed enters through the endoderm. 4. Several sources of evidence confirm that the water within the enteron is poorly oxygenated. Rhythmically fluctuating records of the oxygen concentration of water which has flowed past expanded specimens are the result of periodic expulsions of some of this relatively deoxygenated enteric water. 5. The irrigation of the enteron is very probably brought about by peristaltic waves of contraction which pass along the length of the animal.

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.

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.

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.

Bradygastrias and Mixed Dysrhythmias

2003 ◽  
Keyword(s):  
Contractile Activity ◽  
Low Frequency ◽  
High Amplitude ◽  
Intraluminal Pressure ◽  
Pressure Sensing ◽  
Recording Channel ◽  
Low Amplitude ◽  
Peristaltic Contractions ◽  
The Relationship ◽  
Exact Origin

Bradygastrias are low-frequency electrogastrogram (EGG) waves that range from approximately 1.0 to 2.5 cycles per minute (cpm) . Some bradygastria waves are high amplitude and occupy the full scale of the EGG recording channel; others are very low amplitude and appear to be almost flatline. Bradygastrias have been recorded in patients with functional dyspepsia, diabetic and idiopathic gastropathy, and nausea of pregnancy. These patients have symptoms of abdominal discomfort, fullness, nausea, and vomiting. In this chapter, the causes of bradygastria patterns are reviewed and examples of bradygastrias are shown. EGGs also may have increased bradygastria and tachygastria waves, a pattern termed a mixed dysrhythmia. The exact origin of bradygastrias has been difficult to determine. In certain circumstances, the antrum contracts at 1.5 to 1.8 contractions per minute rather than the more recognized 3-per-minute contractions. Figure 8.1 indicates the relationship between EGG waves and low-frequency antral peristaltic contractions recorded from an intraluminal pressure sensing device during fasting and after infusion of erythromycin in healthy individuals. The antral contractions were recorded 3 and 1.5 cm from the pylorus. During fasting, 2-cpm EGG waves were present and correlated with 2-per-minute antral contractions. Each of these low-frequency contractions was associated with a low-frequency EGG wave (a negative deflection followed by a positive deflection). Irregular antral attractions also occur during fasting and may be reflected in the EGG as 1- to 2-cpm EGG waves. After erythromycin infusion, the EGG waves occurred at 1.0 to 1.5cpm and correlated with stronger antral contractions that occurred at the same frequency: 1.0 to 1.5 per minute. Thus, the bradygastria EGG frequencies correlated with the low-frequency antral contractions during fasting and after infusion of erythromycin. These studies indicate that, under certain conditions, bradygastria waves reflect low-frequency antral contractions. The fundus of the stomach normally contracts slowly at a rate from 0.5 to 1 contraction per minute.15 Thus, the low-frequency contractile activity of the fundus may also be reflected in the low frequency EGG signals in certain situations.

Recovery of Signals Distorted by Sensor Nonlinearity

2004 ◽  
Vol 126 (4) ◽  
pp. 848-859 ◽  
Author(s):  
Sugathevan Suranthiran ◽  
Suhada Jayasuriya
Keyword(s):  
Model Identification ◽  
Low Frequency ◽  
High Amplitude ◽  
Signal Recovery ◽  
Nonlinear Characteristics ◽  
Sensor Model ◽  
Physical Sensor ◽  
Low Amplitude ◽  
Unique Signal ◽  
Original Information

Considered in this paper is a framework for addressing sensor issues that are related to nonlinearity. When a signal is picked up by a nonlinear sensor, it is often the case that the high amplitude part of the signal is distorted by nonlinearity and the low amplitude part is indistinguishable from noise. The distorted output or sensed signal may no longer represent the original input signal due to the presence of high and low frequency foreign spikes in its frequency spectrum. This situation poses a challenging problem: Would it be possible to uniquely extract the original information from the distorted output? A treatment of this problem is given and it is shown that unique signal recovery is possible when the nonlinear characteristics of the sensor satisfy certain requirements. Based on the analysis, an algorithm is developed to recover finite length signals and its validity and efficiency are demonstrated by simulation results. When the sensor model is not available, it is shown how a model identification scheme may be incorporated into the developed scheme. Experiments performed on a physical sensor support the proposed recovery scheme.

scholarly journals Development of Piezoelectric Ultrasonic Thrombolysis Device for Blood Clot Emulsification

2012 ◽  
Vol 2012 ◽  
pp. 1-6
Author(s):  
Tao Li ◽  
Jan Ma ◽  
S. Dinesh Kumar ◽  
Adrian F. Low
Keyword(s):  
Blood Vessel ◽  
High Power ◽  
Vibration Mode ◽  
Pressure Field ◽  
Blood Clot ◽  
Low Frequency ◽  
High Amplitude ◽  
Field Pattern ◽  
Cavitation Effect ◽  
Low Amplitude

Ultrasonic thrombolysis is an effective method to treat blood clot thrombus in a blood vessel. This paper reports an OD 5 mm and an OD 10 mm piezoelectric thrombolysis transducers that vibrate longitudinally and generate a pressure field at the distal vibration tip. Studies of vibration mode, pressure field pattern, and cavitation effect were carried out. The transducers were also tested for blood clot emulsification. The results indicate both transducers are effective. The OD 10 mm transducer with a long transmission wire has shown to provide a strong cavitation effect and work effectively at low frequency, high amplitude, and high power conditions. The OD 5 mm transducer was found to operate effectively under higher frequency, low amplitude, and lower power conditions. The cavitation effect is moderate, which facilitates precision and controls over obtaining a more uniform emulsification result.

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.

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