Calibration and use of pressure transducers in soil hydrology

This study introduces an experimental method that can measure air pressures in the vane segments when a sliding-vane rotary compressor performs suction and compression phases in stable or unstable rotational speeds. When the air pressures of these two phases can be measured, the intake effect of the compressor’s inlet and the seal effect of the vane segments can be evaluated, respectively. Because a frequency converter provides unstable rotational speeds when it controls rotational speeds of a motor with a compressor, an encoder mounted on the output shaft of the motor was applied to record the angular location of the compressor rotor. Two strain gauge type pressure transducers were inserted into the cover plate of the compressor to measure air pressures in the vane segments. Comparing the signals of the encoder with pressure transducers, the air pressures in completions of suction and compression phases could be determined in stable or unstable rotational speeds. The air pressures when the compressor performed suction and compression phases were 99.5 kPa and 153 kPa, respectively, in 1400 rpm. The air pressure when the compressor performed suction phase decreased with the rotational speed faster than 800 rpm. The size or shape of the inlet port of the compressor should be enlarged or modified to provide the suction air pressure without dropping too much. The designed air pressure when the compressor performed compression phase was 244 kPa in 140 rpm, the manufacture precision of the compressor should be increased to decrease leakage.

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Method for prolonged ambulatory monitoring of high-amplitude propagated contractions from colon

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1991.261.2.g263 ◽

1991 ◽

Vol 261 (2) ◽

pp. G263-G268 ◽

Cited By ~ 12

Author(s):

M. D. Crowell ◽

G. Bassotti ◽

L. J. Cheskin ◽

M. M. Schuster ◽

W. E. Whitehead

Keyword(s):

Bowel Movement ◽

Anal Verge ◽

Ambulatory Monitoring ◽

High Amplitude ◽

X Ray ◽

Pressure Transducers ◽

Peristaltic Activity ◽

Bowel Prep ◽

Asymptomatic Individuals ◽

State Pressure

This study monitored high-amplitude propagated contractions (HAPCs) in ambulating subjects over a 24-h period using a new ambulatory recording system. Twelve healthy volunteers aged 34 +/- 5.96 yr participated. Approximately 12 h after a Colyte bowel prep, a small catheter (OD less than 3 mm), containing three solid-state pressure transducers spaced 5 cm apart, was positioned by flexible sigmoidoscope at 40-50 cm from the anal verge. A battery-operated data recorder sampled the pressure at each port at 1 Hz and stored the values on all ports if any port exceeded 75 mmHg. At the conclusion of the 24-h period, an X-ray was taken to confirm the location of the catheter. Fifty-four percent of all HAPCs preceded a bowel movement by less than or equal to 1 h. Forty-nine percent of all HAPCs occurred within 1 h after a high-fat meal, and 33% occurred within 1 h of morning awakening. Reverse propagated waves, not previously described in the colon, were observed in three individuals. Spontaneous high-amplitude caudally propagated contractions occur 6.9 +/- 1.5 times/24 h in the sigmoid colon in ambulating asymptomatic individuals and are temporally related to defecation and meals. Peristaltic activity is decreased during sleep. This recording technique was reliable and well tolerated in all participants.

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Applications of the Numerical Method of Lines (NMOL) in Soil Hydrology

Transactions of the ASAE ◽

10.13031/2013.30427 ◽

1987 ◽

Vol 30 (1) ◽

pp. 0198-0201 ◽

Cited By ~ 4

Author(s):

Shiv O. Prasher ◽

Chandra Madramootoo

Keyword(s):

Numerical Method ◽

Method Of Lines ◽

Soil Hydrology

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Willows Used for Phytoremediation Increased Organic Contaminant Concentrations in Soil Surface

Applied Sciences ◽

10.3390/app11072979 ◽

2021 ◽

Vol 11 (7) ◽

pp. 2979

Author(s):

Maxime Fortin Faubert ◽

Dominic Desjardins ◽

Mohamed Hijri ◽

Michel Labrecque

Keyword(s):

Soil Surface ◽

Field Work ◽

Field Studies ◽

Soil Hydrology ◽

Intensive Culture ◽

Shrub Species ◽

Short Rotation ◽

Pollutant Concentrations ◽

Polycyclic Aromatic ◽

Made In

The Salix genus includes shrub species that are widely used in phytoremediation and various other phytotechnologies due to their advantageous characteristics, such as a high evapotranspiration (ET) rate, in particular when cultivated in short rotation intensive culture (SRIC). Observations made in past field studies suggest that ET and its impact on soil hydrology can also lead to increases in soil pollutant concentrations near shrubs. To investigate this, sections of a mature willow plantation (seven years old) were cut to eliminate transpiration (Cut treatment). Soil concentrations of polychlorinated biphenyls (PCBs), aliphatic compounds C10–C50, polycyclic aromatic hydrocarbons (PAHs) and five trace elements (Cd, Cr, Cu, Ni and Zn) were compared between the Cut and the uncut plots (Salix miyabeana ‘SX61’). Over 24 months, the results clearly show that removal of the willow shrubs limited the contaminants’ increase in the soil surface, as observed for C10–C50 and of 10 PAHs under the Salix treatment. This finding strongly reinforces a hypothesis that SRIC of willows may facilitate the migration of contaminants towards their roots, thus increasing their concentration in the surrounding soil. Such a “pumping effect” in a high-density willow crop is a prominent characteristic specific to field studies that can lead to counterintuitive results. Although apparent increases of contaminant concentrations contradict the purification benefits usually pursued in phytoremediation, the possibility of active phytoextraction and rhizodegradation is not excluded. Moreover, increases of pollutant concentrations under shrubs following migration suggest that decreases would consequently occur at the source points. Some reflections on interpreting field work results are provided.

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Investigation into the Relationship between Super-Knock and Misfires in an SI GDI Engine

Energies ◽

10.3390/en14082099 ◽

2021 ◽

Vol 14 (8) ◽

pp. 2099

Author(s):

Jian Gao ◽

Anren Yao ◽

Yeyi Zhang ◽

Guofan Qu ◽

Chunde Yao ◽

...

Keyword(s):

Pressure Fluctuation ◽

Direct Injection ◽

Exhaust Valve ◽

Gasoline Direct Injection ◽

Exhaust Pipe ◽

Pressure Transducers ◽

Spark Plug ◽

Si Engines ◽

Gdi Engine ◽

The Relationship

The super-knock poses new challenges for further increasing the power density of spark ignition (SI) engines. The critical factors and mechanism connecting regarding the occurrence of super-knock are still unclear. Misfire is a common phenomenon in SI engines that the mixture in cylinder is not ignited normally, which is often caused by spark plug failure. However, the effect of misfire on engine combustion has not been paid enough attention to, particularly regarding connection to super-knock. The paper presents the results of experimental investigation into the relationship between super-knock and misfires at low speed and full load conditions. In this work, a boosted gasoline direct injection (GDI) engine with an exhaust manifold integrated in the cylinder head was employed. Four piezoelectric pressure transducers were used to acquire the data of a pressure trace in cylinder. The spark plugs of four cylinders were controlled manually, of which the ignition system could be cut off as demanded. In particular, a piezoelectric pressure transducer was installed at the exhaust pipe before the turbocharger to capture the pressure traces in the exhaust pipe. The results illustrated that misfires in one cylinder would cause super-knock in the other cylinders as well as the cylinder of itself. After one cylinder misfired, the unburned mixture would burn in the exhaust pipe to produce oscillating waves. The abnormal pressure fluctuation in the exhaust pipe was strongly correlated with the occurrence of super-knock. The sharper the pressure fluctuation, the greater the intensity of knock in the power cylinder. The cylinder whose exhaust valve overlapped with the exhaust valve of the misfired cylinder was prone to super-knock.

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Experimentally Determined Stability Parameters of a Subsonic Cascade Oscillating Near Stall

Journal of Engineering for Power ◽

10.1115/1.3446301 ◽

1978 ◽

Vol 100 (1) ◽

pp. 111-120 ◽

Cited By ~ 10

Author(s):

F. O. Carta ◽

A. O. St. Hilaire

Keyword(s):

Phase Angle ◽

Incidence Angle ◽

Minor Effect ◽

Significant Finding ◽

Force Coefficient ◽

Stability Parameters ◽

Free System ◽

Pressure Transducers ◽

Moment Coefficient ◽

The Stability

Tests were performed on a linear cascade of airfoils oscillating in pitch about their midchords at frequencies up to 17 cps, at free-stream velocities up to 200 ft/s, and at interblade phase angles of 0 deg and 45 deg, under conditions of high aerodynamic loading. The measured data included unsteady time histories from chordwise pressure transducers and from chordwise hot films. Unsteady normal force coefficient, moment coefficient, and aerodynamic work per cycle of oscillation were obtained from integrals of the pressure data, and indications of the nature and extent of the separation phenomenon were obtained from an analysis of the hot-film response data. The most significant finding of this investigation is that a change in interblade phase angle from 0 deg to 45 deg radically alters the character of the unsteady blade loading (which governs its motion in a free system) from stable to unstable. Furthermore, the stability or instability is governed primarily by the phase angle of the pressure distribution (relative to the blade motion) over the forward 10–15 percent of the blade chord. Reduced frequency and mean incidence angle changes were found to have a relatively minor effect on stability for the range of parameters tested.

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