A LABORATORY MESOCOSM AS A TOOL TO STUDY PAH DEGRADATION IN A COASTAL MARSH WETLAND

2014 ◽  
Vol 2014 (1) ◽  
pp. 400-407
Author(s):  
Doorce S. Batubara ◽  
Donald D. Adrian ◽  
Martin S. Miles ◽  
Ronald F. Malone
Keyword(s):  
High Tide ◽  
Air Pressure ◽  
Coastal Marsh ◽  
Wetland Soil ◽  
Phenanthrene Degradation ◽  
Pah Degradation ◽  
Tidal Water ◽  
Air Chamber ◽  
Marsh Wetland ◽  
Intertidal Wetland

ABSTRACT Polycyclic aromatic hydrocarbons (PAHs) are one of the contaminants of concern in coastal marsh environments which are subject to crude oil spills. A laboratory scale mesocosm can be used to complement field study of PAH degradation in coastal marshes. Coastal marsh wetland features, such as its soil, tidal cycles, and flushing, that may play roles in PAH degradation can be simulated in a laboratory mesocosm. The laboratory mesocosm tank is made of acrylic as the main construction material with an air chamber inside the tank which functions as a pneumatic system and tidal water storage compartment. Two trays filled with contaminated marsh wetland soil are situated at two different levels: the lower one is constantly submerged while the higher one is intermittently drained. When the air pressure inside the air chamber is high, the water will flow out from the air chamber to the tank to create high tide. When the air pressure inside the air chamber is low, the water will flow back from the tank to the air chamber to create low tide inside the tank. The tidal water sits in the air chamber until the next high air pressure. The cycles of air pressure inside the tank are controlled by an electrical air pump connected to a timer. The experimental setup can consist of several replicates with an air chamber inside each replicate is controlled by a master pneumatic tank. The model PAH contaminant used in the experiment was phenanthrene, a three-benzene-ring PAH, which was spiked to the wetland soil. The experimental results show that the phenanthrene degradation in the intertidal wetland soil is higher than that of in the subtidal wetland soil presumably due to the availability of oxygen in the intertidal wetland soil. The laboratory mesocosm developed in this study can be used as a tool for examining PAH degradation and other non-volatile organic contaminants.

Scale and Configuration Effects of an Airchamber on PTO of Oscillating Water Column Type Wave Energy Converters

2021 ◽  
Author(s):  
Tomoki Ikoma ◽  
Shota Hirai ◽  
Yasuhiro Aida ◽  
Koichi Masuda
Keyword(s):  
Water Column ◽  
Wave Energy ◽  
Water Surface ◽  
Air Pressure ◽  
Scale Model ◽  
Linear Potential ◽  
Oscillating Water Column ◽  
Wave Energy Converters ◽  
Air Chamber ◽  
Energy Converters

Abstract Wave energy converters (WECs) have been extensively researched. The behaviour of the oscillating water column (OWC) in OWC WECs is extremely complex due to the interaction of waves, air, and turbines. Several problems must be overcome before such WECs can be put to practical use. One problem is that the effect of the difference in scale between a small-scale experimental model and a full-scale model is unclear. In this study, several OWC models with different scales and geometries were used in forced oscillation tests. The wave tank was 7.0 m wide, 24.0 m long, and 1.0 m deep. In the static water experiment, we measured the air pressure and water surface fluctuations in an air chamber. For the experiments, models with a box shape with an open bottom, a manifold shape with an open bottom, and a box shape with a front opening, respectively, were fabricated. Furthermore, 1/1, 1/2, and 1/4 scale models were fabricated for each shape to investigate the effects of scale and shape on the air chamber characteristics. Numerical calculations were carried out by applying linear potential theory and the results were compared with the experimental values. The results confirmed that the air chamber shape and scale affect the air pressure fluctuation and water surface fluctuation inside the OWC system.

scholarly journals Self-excited air flow passage changing device for periodic pressurization of soft robot

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Toshio Takayama ◽  
Yusuke Sumi
Keyword(s):  
Mobile Robot ◽  
Rotational Motion ◽  
Air Pressure ◽  
Soft Robot ◽  
Pressure Source ◽  
Large Delay ◽  
Soft Robots ◽  
Flow Passage ◽  
Output Pressure ◽  
Air Chamber

AbstractRecently pneumatic-driven soft robots have been widely developed. Usually, the operating principle of this robot is the inflation and deflation of elastic inflatable chambers by air pressure. Some soft robots need rapid and periodic inflation and deflation of their air chambers to generate continuous motion such as progress motion or rotational motion. However, if the soft robot needs to operate far from the air pressure source, long air tubes are required to supply air pressure to its air chambers. As a result, there is a large delay in supplying air pressure to the air chamber, and the motion of the robot slows down. In this paper, we propose a compact device that changes its airflow passages by self-excited motion generated by a supply of continuous airflow. The diameter and the length of the device are 20 and 50 mm, respectively, and can be driven in a small pipe. Our proposed in-pipe mobile robot is connected to the device and can move in a small pipe by dragging the device into it. To apply the device widely to other soft robots, we also discuss a method of adjusting the output pressure and motion frequency.

Improvement of Wave Power Take-Off Performance due to the Projecting Walls for OWC Type WEC

2013 ◽  
Author(s):  
Tomoki Ikoma ◽  
Koichi Masuda ◽  
Hikaru Omori ◽  
Hiroyuki Osawa ◽  
Hisaaki Maeda
Keyword(s):  
Prediction Method ◽  
Air Pressure ◽  
Wave Power ◽  
Linear Potential ◽  
Oscillating Water Column ◽  
Air Chamber ◽  
Pressure Water ◽  
Linear Potential Theory ◽  
Hydrodynamic Behaviors ◽  
Water Elevation

This paper describes a method in order to improve the performance of the primary conversion of wave power take-off. A corresponding wave energy convertor (WEC) is an oscillating water column (OWC) type. The method of the improvement has been proposed and its usefulness has been confirmed in past researches. In the method, projecting walls were attached onto front of inlet-outlet of OWC. The prediction method of hydrodynamic behaviors for the projecting walls installed OWC type WEC is explained in the paper. The boundary element method with the Green’s function is applied and influence of air pressure and free surface within every an air-chamber was directly taken into consideration in the prediction method based on a linear potential theory. Validity of the prediction method was proved comparing with results of model experiments. Series calculations are performed with the prediction method. Behaviors of air pressure, water elevation and the efficiency of primary conversion of wave power are investigated. From the calculations, length of the projecting walls was shown to affect the efficiency of primary conversion. It was available to equip the projecting walls for the improvement in oblique waves to beam sea condition as well as head sea condition. As well as only the projecting walls, application and effects of the end walls with the slit were investigated in the paper. The end walls were very useful to improve the efficiency.

scholarly journals Self-Excited Air Flow Passage Changing Device for Periodic Pressurization of Soft Robot

2021 ◽  
Author(s):  
Toshio Takayama ◽  
Yusuke Sumi
Keyword(s):  
Mobile Robot ◽  
Rotational Motion ◽  
Air Pressure ◽  
Soft Robot ◽  
Pressure Source ◽  
Large Delay ◽  
Soft Robots ◽  
Flow Passage ◽  
Output Pressure ◽  
Air Chamber

Abstract Recently pneumatic-driven soft robots have been widely developed. Usually, the operating principle of this robot is the inflation and deflation of elastic inflatable chambers by air pressure. Some soft robots need rapid and periodic inflation and deflation of their air chambers to generate continuous motion such as progress motion or rotational motion. However, if the soft robot needs to operate far from the air pressure source, long air tubes are required to supply air pressure to its air chambers. As a result, there is a large delay in supplying air pressure to the air chamber, and the motion of the robot slow down. In this paper, we propose a compact device that changes its airflow passages by self-excited motion generated by a supply of continuous airflow. The diameter and the length of the device are 20 and 50 mm, respectively, and can be driven in a small pipe. Our proposed in-pipe mobile robot is connected to the device and can move in a small pipe by dragging the device into it. To apply the device widely to other soft robots, we also discuss a method of adjusting the output pressure and motion frequency.

scholarly journals Characterization of the Phenanthrene-Degrading Sphingobium yanoikuyae SJTF8 in Heavy Metal Co-Existing Liquid Medium and Analysis of Its Metabolic Pathway

2020 ◽  
Vol 8 (6) ◽  
pp. 946 ◽  
Author(s):  
Chong Yin ◽  
Weiliang Xiong ◽  
Hua Qiu ◽  
Wanli Peng ◽  
Zixin Deng ◽  
...  
Keyword(s):  
Aromatic Hydrocarbons ◽  
Sole Carbon Source ◽  
Genome Mining ◽  
Whole Genome Sequence ◽  
Phenanthrene Degradation ◽  
Pah Degradation ◽  
Polycyclic Aromatic ◽  
Degradation Ability ◽  
Halogenated Aromatic Compounds

Polycyclic aromatic hydrocarbons (PAHs) are common organic pollutants with great carcinogenic threaten, and metal/PAH-contaminated environments represent one of the most difficult remedial challenges. In this work, Sphingobium yanoikuyae SJTF8 was isolated and identified with great and stable PAH-degrading efficiency even under stress conditions. It could utilize typical PAHs (naphthalene, phenanthrene, and anthracene) and heterocyclic and halogenated aromatic compounds (dibenzothiophene and 9-bromophenanthrene) as the sole carbon source. It could degrade over 98% of 500 mg/L phenanthrene in 4 days, and the cis-3,4-dihydrophenanthrene-3,4-diol was the first-step intermediate. Notably, strain SJTF8 showed great tolerance to heavy metals and acidic pH. Supplements of 0.30 mM of Cu2+, 1.15 mM of Zn2+, and 0.01 mM of Cd2+ had little effect on its cell growth and phenanthrene degradation; phenanthrene of 250 mg/L could still be degraded completely in 48 h. Further, the whole genome sequence of S. yanoikuyae SJTF8 was obtained, and three plasmids were found. The potential genes participating in stress-tolerance and PAH-degradation were annotated and were found mostly distributed in plasmids 1 and 2. Elimination of plasmid 2 resulted in the loss of the PAH-degradation ability. On the basis of genome mining results, the possible degrading pathway and the metabolites of S. yanoikuyae SJTF8 to phenanthrene were predicted.

Design and Analysis of Pneumatic Bending Actuator Used in Soft Robotics

2021 ◽  
Vol 105 ◽  
pp. 194-201
Author(s):  
Xu Dong Wang ◽  
Heng Wei Chen ◽  
Liao Wang ◽  
Wen Zhou ◽  
Yi Qing Li
Keyword(s):  
Nonlinear Problems ◽  
Element Model ◽  
Air Pressure ◽  
Experimental Comparison ◽  
Pneumatic Actuators ◽  
Air Chamber ◽  
Bending Actuator ◽  
Continuous Bending ◽  
Soft Actuators ◽  
The Finite Element Model

Pneumatic soft actuators can change their shapes under pneumatic pressure actuation and are capable of continuous bending. However, the air chambers inside will expand during the actuation process and cause nonlinear problems. Therefore pneumatic actuators are difficulties to model. In this paper, three types of bending actuators with different air chamber shapes are designed and the finite element model (FEM) is developed to simulate the deformation under different air pressure actuation. A prototype of the bending actuator is fabricated and a method to limit the expansion of the air chamber is designed based on the FEM results, which can effectively improve the expansion and the response of the actuator under low air pressure conditions through experimental comparison.

scholarly journals Study of CO2 flux and soil carbon in northern Pantanal, Brazil

2018 ◽  
Vol 9 (5) ◽  
pp. 29-38
Author(s):  
Osvaldo Borges Pinto Junior ◽  
Paula Valéria Carvalho ◽  
Eduardo Guimarães Couto
Keyword(s):  
Carbon Source ◽  
Soil Carbon ◽  
High Tide ◽  
Co2 Flux ◽  
Co2 Concentration ◽  
Wetland Soil ◽  
Co2 Fluxes ◽  
Soil Co2 ◽  
Mato Grosso ◽  
Tree Island

The determination of greenhouse gas emissions from wetlands are of great interest given the biogeochemistry these areas exhibit. We measure soil CO2 concentration and monthly fluxes on a tree island of the Northern Pantanal of Mato Grosso, Brazil, and estimate the role of soil as a carbon source or sink during high tide, low tide, flooding, and drought seasons. The average value of the CO2 fluxes in the wetland soil was 0.54 ± 0.30 g (CO2)·m- 2·h- 1 with the soil acting as a carbon source at -9.11 ton.·ha-1 over the one year cycle. Soil CO2 fluxes were significantly correlated with soil moisture and temperature at 5 cm depth. Soil CO2 concentrations reached more than 100 ppm. Soil carbon stocks did not correlate significantly with variables in this study, suggesting that non-measured variables can influence soil carbon dynamics.

An experimental study of the pattern and significance of the climbing behaviour of Hydrobia ulvae

1981 ◽  
Vol 61 (2) ◽  
pp. 285-299 ◽  
Author(s):  
R. S. K. Barnes
Keyword(s):  
Population Density ◽  
Laboratory Experiments ◽  
Field Experiments ◽  
High Tide ◽  
Field Observations ◽  
Laboratory Studies ◽  
Hydrobia Ulvae ◽  
Tidal Water ◽  
Climbing Behaviour ◽  
Incoming Tide

The climbing behaviour of the gastropod Hydrobia ulvae (Pennant) and its relationship with flotation/dispersal were investigated by field observations and experiments in Norfolk, U.K. and by laboratory experiments. Field experiments of the type used by previous authors were discontinued when it was observed that counts at low tide of snails which had climbed objects the previous high tide did not reflect adequately climbing activity during that period of tidal cover. Both field and laboratory studies yielded five general results: (i) snails climbed only when covered by tidal water; (ii) climbing activity was not related to population density; (iii) climbing activity, under conditions of constant population density, varied markedly during the cycle of spring tidal cover, reaching a peak after the first few tides and declining rapidly thereafter; (iv) maximum numbers of snails were present on submerged structures relatively early in any given period of cover and declined (snails crawled downwards off the structure) as the period of cover continued; and (v) rarely were large proportions of climbed Hydrobia floated off their support by the incoming tide; this was associated only with conditions of extreme calm.

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