scholarly journals Accuracy and Uncertainty of Gradient Based Leak Localization Procedure for Liquid Transmission Pipelines

Sensors ◽  
2021 ◽  
Vol 21 (15) ◽  
pp. 5080
Author(s):  
Pawel Ostapkowicz ◽  
Andrzej Bratek
Keyword(s):  
Measurement Data ◽  
Uncertainty Assessment ◽  
Laboratory Model ◽  
Pressure Gradients ◽  
Pressure Measurements ◽  
Low Intensity ◽  
Measuring Devices ◽  
Gradient Based ◽  
Leak Localization ◽  
Transmission Pipelines

This paper describes issues of leakage localization in liquid transmission pipelines. It focuses on the standard leak localization procedure, which is based on the calculation of pressure gradients using pressure measurements captured along a pipeline. The procedure was verified in terms of an accuracy and uncertainty assessment of the resultant coordinate of a leak spot. An important aim of the verification was to assess the effectiveness of the procedure in the case of localization of low intensity leakages with a level of 0.25–2.00% of the nominal flow rate. An uncertainty assessment was carried out according to the GUM convention. The assessment was based on the metrological characteristics of measuring devices and measurement data obtained from the laboratory model of the pipeline.

The Study of Evaporation from Small Surfaces by the Direct Measurement of Water Vapour Pressure Gradients

1970 ◽  
Vol 53 (3) ◽  
pp. 753-762
Author(s):  
JOHN MACHIN
Keyword(s):  
Water Vapour ◽  
Direct Measurement ◽  
Vapour Pressure ◽  
Point Method ◽  
Dew Point ◽  
Water Vapour Pressure ◽  
Pressure Gradients ◽  
Pressure Measurements ◽  
Wind Speeds ◽  
Experimental Values

1. The construction, maintenance and calibration of a sensitive instrument capable of making numerous vapour-pressure measurements within humidity gradients by the dew-point method is described. 2. Coefficients of diffusion of water vapour in air, calculated from observed vapour-pressure gradients and measured rates of evaporation agree with theoretical and other experimental values in still air. 3. Apparent coefficients in wind speeds between 10 and 100 cm/s were significantly lower than those in still air. 4. This finding, together with the performance of the dew-point probe, is discussed in relation to its possible use in the study of evaporation from animals and plants.

A comparison of CAT Doppler and oscillometric Memoprint machines for non-invasive blood pressure measurement in conscious cats

2005 ◽  
Vol 7 (3) ◽  
pp. 147-152 ◽  
Author(s):  
Rosanne E. Jepson ◽  
Vivien Hartley ◽  
Michael Mendl ◽  
Sarah ME Caney ◽  
David J Gould
Keyword(s):  
Blood Pressure ◽  
Systolic Blood Pressure ◽  
Diastolic Blood Pressure ◽  
Blood Pressure Measurement ◽  
Systemic Hypertension ◽  
Pressure Measurements ◽  
Non Invasive ◽  
Measuring Devices ◽  
Oscillometric Device ◽  
Significant Difference

Indirect blood pressure measurements were compared in 28 conscious cats using Doppler and oscillometric blood pressure-measuring devices. Ten cats were used to compare Doppler measurements between two examiners and 18 cats were used to compare Doppler and oscillometric measurements. The Doppler machine obtained systolic and diastolic blood pressure readings in 100% and 51% of attempts, respectively. With the oscillometric machine, systolic and diastolic blood pressure readings were obtained in 52% of the attempts. With the Doppler, measures of mean systolic blood pressure between two examiners were positively correlated, but there was no correlation for diastolic blood pressure measures. When comparing the results obtained by Doppler and oscillometric machines there was no significant difference between mean systolic blood pressure readings, but the oscillometric machine produced significantly higher estimates of diastolic blood pressure. In both cases, the standard deviations for the oscillometric machine were considerably larger than those for the Doppler machine. The first reading of systolic blood pressure obtained with the Doppler machine was an excellent predictor of the mean of five readings, but this was not so for the oscillometric machine. It took less than 5 min to obtain five readings in 37.5% of cases with the Doppler machine but this was true for only 5% of cases with the oscillometric machine. Two cats with ophthalmological lesions consistent with systemic hypertension were identified. In these two patients, systolic blood pressure measurements were between 200 and 225 mmHg when measured by Doppler, and between 140 and 150 mmHg when measured by the oscillometric machine. This suggests that a lower reference range for normal systolic blood pressure values should be used for the oscillometric device.

scholarly journals Raspberry Pi-Based Low-Cost Connected Device for Assessing Road Surface Friction

Electronics ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 341 ◽  
Author(s):  
Miha Ambrož ◽  
Uroš Hudomalj ◽  
Alexander Marinšek ◽  
Roman Kamnik
Keyword(s):  
Traffic Safety ◽  
Road Network ◽  
Low Cost ◽  
Measurement Data ◽  
Automatic Measurement ◽  
Raspberry Pi ◽  
Measuring Device ◽  
The Road ◽  
Measuring Devices ◽  
On The Road

Measuring friction between the tyres of a vehicle and the road, often and on as many locations on the road network as possible, can be a valuable tool for ensuring traffic safety. Rather than by using specialised equipment for sequential measurements, this can be achieved by using several low-cost measuring devices on vehicles that travel on the road network as part of their daily assignments. The presented work proves the hypothesis that a low cost measuring device can be built and can provide measurement results comparable to those obtained from expensive specialised measuring devices. As a proof of concept, two copies of a prototype device, based on the Raspberry Pi single-board computer, have been developed, built and tested. They use accelerometers to measure vehicle braking deceleration and include a global positioning receiver for obtaining the geolocation of each test. They run custom-developed data acquisition software on the Linux operating system and provide automatic measurement data transfer to a server. The operation is controlled by an intuitive user interface consisting of two illuminated physical pushbuttons. The results show that for braking tests and friction coefficient measurements the developed prototypes compare favourably to a widely used professional vehicle performance computer.

Dependence of Intervertebral Disc Pressure Generation on Load History

2009 ◽  
Author(s):  
David Hwang ◽  
Miao Yu ◽  
Adam H. Hsieh
Keyword(s):  
Intervertebral Disc ◽  
Animal Studies ◽  
Sensor Technology ◽  
Laboratory Model ◽  
Large Animal ◽  
Pressure Measurements ◽  
Load History ◽  
Local Stresses ◽  
History Of ◽  
Rat Tail

It has been thoroughly documented that low back pain is often associated with deregulated biological function and compromised mechanical behavior of the intervertebral disc. Therefore, intervertebral disc mechanics have long been thought of as important factors both in driving cell-mediated processes involved in degeneration and in distinguishing between healthy versus degenerate discs. The nucleus pulposus is an integral part of the mechanics of the disc, the key property being its ability to pressurize to resist and distribute compressive stress to the annulus fibrosus and the endplates. There has been a history of intradiscal pressure measurements in cadaveric as well as large animal studies; however, these studies have focused on the consequences of degeneration or the change in stress distribution by varying spinal orientations. In order to be able to relate local stresses induced in discs to changes in cellular function, such pressure measurements must be obtained from an animal model amenable to chronic disc loading. Rat tail discs have been one widely used laboratory model, but the discs are too small for measuring load-induced nucleus pressures using current sensor technology.

Correlation-Based Riblet Model for Turbomachinery Applications

2017 ◽  
Vol 139 (7) ◽  
Author(s):  
Viktor Koepplin ◽  
Florian Herbst ◽  
Joerg R. Seume
Keyword(s):  
Three Dimensional ◽  
Measurement Data ◽  
Navier Stokes ◽  
Pressure Gradients ◽  
Compressor Cascade ◽  
Design Code ◽  
Experimental Values ◽  
Turbomachinery Design ◽  
Plate Measurement ◽  
Good Agreement

An empirical riblet model for manufactured V-shaped and trapezoidal riblets which is suitable for turbomachinery application is presented. The implementation of the riblet effect employs a correlation-based correction for the damping of the specific dissipation rate ω in the vicinity of the wall which has been previously presented by other researchers. In the current paper, the correlations are extended into the drag-increasing regime and are extended to account for the effect of misalignment of the riblets relative to the flow and for the effect of adverse pressure gradients. In order to account for the latter in modern, massive parallel Reynolds-averaged Navier–Stokes (RANS) codes, a local Clauser parameter has been newly derived. The model is implemented in a three-dimensional (3D) turbomachinery design code and validated with flat plate measurement data and a NACA6510 compressor cascade. The predictions of the experimental values are in very good agreement with the experimental data, showing the capability of the model for designing riblet structured turbomachinery blading.

Diurnal Cycle of Thermally Driven Cross-Basin Winds in Arizona’s Meteor Crater

2011 ◽  
Vol 50 (3) ◽  
pp. 729-744 ◽  
Author(s):  
Manuela Lehner ◽  
C. David Whiteman ◽  
Sebastian W. Hoch
Keyword(s):  
Diurnal Cycle ◽  
Inversion Layer ◽  
Crater Floor ◽  
Pressure Gradients ◽  
Pressure Measurements ◽  
Westerly Winds ◽  
Thermally Driven ◽  
Temperature And Pressure ◽  
The Cross

Abstract Cross-basin winds produced by asymmetric insolation of the crater sidewalls occur in Arizona’s Meteor Crater on days with weak background winds. The diurnal cycle of the cross-basin winds is analyzed together with radiation, temperature, and pressure measurements at the crater sidewalls for a 1-month period. The asymmetric irradiation causes horizontal temperature and pressure gradients across the crater basin that drive the cross-basin winds near the crater floor. The horizontal temperature and pressure gradients and wind directions change as the sun moves across the sky, with easterly winds in the morning and westerly winds in the evening. A case study of 12 October 2006 further illustrates the obtained relation between these parameters for an individual day. The occurrence of an elevated cross-basin flow on 23 October 2006 is shown to relate to the presence of an elevated inversion layer.

Evaluation of Compression Therapy: Comparison of Three Sub-bandage Pressure Measuring Devices

2002 ◽  
Vol 17 (2) ◽  
pp. 54-58
Author(s):  
C. V. Ruckley ◽  
J. J. Dale ◽  
B. Gibson ◽  
D. Brown ◽  
A. J. Lee ◽  
...  
Keyword(s):  
Statistical Analysis ◽  
Pressure Gradient ◽  
Compression Therapy ◽  
Pressure Measurements ◽  
Measuring Devices ◽  
Bartlett’S Test ◽  
Significant Difference ◽  
Standard Models ◽  
Measurement Variance ◽  
Equidistant Points

Objective: To compare the consistency of the pressure measurements and the practical aspects of three manometers (Salzman MST; Oxford Talley and Diastron) measuring sub-bandage pressures. Methods: Five bandages (tubular elastic straight, tubular elastic graduated, short stretch non-elastic, long stretch elastic, cohesive elastic) were applied to standard models comprising foam-covered 9.5 cm, 12.5 cm diameter plastic tubes and a cone by a single expert bandager using a standard spiral technique with 50% overlap for the non-tubular bandages (NTB). The probes of all three machines were positioned at equidistant points around the circumference of each model at three levels corresponding to the ankle, gaiter and mid-calf measuring points of the MST probe. Two readings were taken for each of three separate applications of each bandage. Statistical analysis utilised ANOVA with Bartlett's test. Results. A total of 135 readings were made for each machine and 81 for each type of bandage. Mean pressures among the five bandages types ranged from 12.2 to 35.5 mmHg. A pressure gradient was apparent when NTB bandaging the straight tubes (means 24.7, 23.5, 22.4 mmHg) but not with the cone. There was a statistically significant difference between the three machines (Bartlett's test 23.6, p<0.0001), with the lowest variances for the MST and similar variances for the Oxford and Diastron. Conclusion. In terms of measurement variance this experiment indicates that the MST is the preferred machine for future experiments.

Dural sinus stent placement for idiopathic intracranial hypertension

2012 ◽  
Vol 116 (3) ◽  
pp. 538-548 ◽  
Author(s):  
David A. Kumpe ◽  
Jeffrey L. Bennett ◽  
Joshua Seinfeld ◽  
Victoria S. Pelak ◽  
Ashish Chawla ◽  
...  
Keyword(s):  
Intracranial Hypertension ◽  
Stent Placement ◽  
Idiopathic Intracranial Hypertension ◽  
Venous Pressure ◽  
Dural Sinus ◽  
Pressure Gradients ◽  
Pressure Measurements ◽  
Junction Region ◽  
Hemodynamic Deterioration

Object The use of unilateral dural sinus stent placement in patients with idiopathic intracranial hypertension (IIH) has been described by multiple investigators. To date there is a paucity of information on the angiographic and hemodynamic outcome of these procedures. The object of this study was to define the clinical, angiographic, and hemodynamic outcome of placement of unilateral dural sinus stents to treat intracranial venous hypertension in a subgroup of patients meeting the diagnostic criteria for IIH. Methods Eighteen consecutive patients with a clinical diagnosis of IIH were treated with unilateral stent placement in the transverse-sigmoid junction region. All patients had papilledema. All 12 female patients had headaches; 1 of 6 males had headaches previously that disappeared after weight loss. Seventeen patients had elevated opening pressures at lumbar puncture. Twelve patients had opening pressures of 33–55 cm H2O. All patients underwent diagnostic cerebral arteriography that showed venous outflow compromise by filling defects in the transverse-sigmoid junction region. All patients underwent intracranial selective venous pressure measurements across the filling defects. Follow-up arteriography was performed in 16 patients and follow-up venography/venous pressure measurements were performed in 15 patients. Results Initial pressure gradients across the filling defects ranged from 10.5 to 39 mm Hg. Nineteen stent procedures were performed in 18 patients. One patient underwent repeat stent placement for hemodynamic failure. Pressure gradients were reduced in every instance and ranged from 0 to 7 mm Hg after stenting. Fifteen of 16 patients in whom ophthalmological follow-up was performed experienced disappearance of papilledema. Follow-up arteriography in 16 patients at 5–99 months (mean 25.3 months, median 18.5 months) showed patency of all stents without in-stent restenosis. Two patients had filling defects immediately above the stent. Four other patients developed transverse sinus narrowing above the stent without filling defects. One of these patients underwent repeat stent placement because of hemodynamic deterioration. Two of the other 3 patients had hemodynamic deterioration with recurrent pressure gradients of 10.5 and 18 mm Hg. Conclusions All stents remained patent without restenosis. Stent placement is durable and successfully eliminates papilledema in appropriately selected patients. Continuing hemodynamic success in this series was 80%, and was 87% with repeat stent placement in 1 patient.

Correlation-Based Riblet Model for Turbomachinery Applications

2016 ◽  
Author(s):  
Viktor Koepplin ◽  
Florian Herbst ◽  
Joerg R. Seume
Keyword(s):  
Dissipation Rate ◽  
Measurement Data ◽  
Pressure Gradients ◽  
Compressor Cascade ◽  
Design Code ◽  
Experimental Values ◽  
Turbomachinery Design ◽  
Plate Measurement ◽  
Parallel Cfd ◽  
Good Agreement

An empirical riblet model for manufactured V-shaped and trapezoidal riblets which is suitable for turbomachinery application is presented. The implementation of the riblet effect employs a correlation-based correction for the damping of the specific dissipation rate omega in the vicinity of the wall which has been previously presented by other researchers. In the current paper the correlations are extended into the drag-increasing regime and are extended to account for the effect of misalignment of the riblets relative to the flow and for the effect of adverse pressure gradients. In order to account for the latter in modern, massive parallel CFD-codes, a local Clauser-Parameter has been newly derived. The model is implemented in the 3D turbomachinery design code TRACE and validated with flat plate measurement data and a NACA6510 compressor cascade. The predictions of the experimental values are in very good agreement with the experimental data, showing the capability of the model for designing riblet structured turbomachinery blading.

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