MCP methodology for intelligent water metering (IWM): assessment of low flow consumption

2012 ◽  
Vol 12 (3) ◽  
pp. 270-280 ◽  
Author(s):  
J. L. Solanas ◽  
M. R. Cussó
Keyword(s):  
Individual Case ◽  
Low Flow ◽  
Flow Volume ◽  
Mean Flow ◽  
Significant Group ◽  
Multivariate Case ◽  
Non Revenue Water ◽  
Analytical Tools ◽  
Water Metering ◽  
Case Classification

Uses at different flows, non-intended consumption or other reasons can cause significant low flow consumption with regard to nominal metering magnitudes. It is important to assess this situation because it could cause measuring and billing inaccuracies due to both non-revenue water and metering errors. MCP (multivariate case profiling) methodology summarizes IWM (intelligent water metering) information by means of categories and levels suited to distinguish different causes concurring on each individual case. We characterised a significant group of ‘Lowflow’ cases showing at the same reading period: ‘significant consumption at normal flows’ but ‘significant continuous consumption at flows lower than normal for intended uses’. We propose variables associated to the new MCP Lowflow category by analysing: (1) lowest intervals of the flow-volume histogram to assess ‘consumption at flows lower than normal’; (2) minimal mean flow in the volume-time histogram to assess ‘intended uses’. MCP yields Lowflow case classification tables, indexes and analytical tools applying those variables, the aim being to detect and assess such abnormal low flow consumptions for any case or group of cases.

Watershed monitoring to address contamination source issues and remediation of the contaminant impairments

2001 ◽  
Vol 44 (7) ◽  
pp. 51-56 ◽  
Author(s):  
P. L. Barnes ◽  
P. K. Kalita
Keyword(s):  
Drinking Water ◽  
Water Treatment ◽  
River Basin ◽  
Low Flow ◽  
Water Quality Criteria ◽  
Mean Flow ◽  
Aquatic Life ◽  
Kansas River ◽  
Public Drinking Water ◽  
Public Drinking

The Big Blue River Basin is located in southeastern Nebraska and northeastern Kansas and consists of surface water in the Big Blue River, Little Blue River, Black Vermillion River, and various tributaries draining 24,968 km2. Approximately 75% of the land area in the basin are cultivated cropland. The Big Blue River flows into Tuttle Creek Reservoir near Manhattan, Kansas. Releases from the lake are used to maintain streamflow in the Kansas River during low flow periods, contributing 27% of the mean flow rate of the Kansas River at its confluence with the Missouri River. Tuttle Creek Reservoir and the Kansas River are used as sources of public drinking water and meet many of the municipal drinking water supply needs of the urban population in Kansas from Junction City to Kansas City. Elevated concentrations of pesticides in the Big Blue River Basin are of growing concern in Kansas and Nebraska as concentrations may be exceeding public drinking water standards and water quality criteria for the protection of aquatic life. Pesticides cause significant problems for municipal water treatment plants in Kansas, as they are not appreciably removed during conventional water treatment processes unless activated carbon filtering is used. Pesticides have been detected during all months of the year with concentrations ranging up to 200 μg/l. If high concentration in water is associated with high flow conditions then large mass losses of pesticides can flow into the water supplies in this basin. This paper will investigate the use of a monitoring program to assess the non-point source of this atrazine contamination. Several practices will be examined that have shown ability to remediate or prevent these impairments.

scholarly journals The Cumulative Effects of Forest Disturbance and Climate Variability on Streamflow in the Deadman River Watershed

Forests ◽  
2019 ◽  
Vol 10 (2) ◽  
pp. 196 ◽  
Author(s):  
Krysta Giles-Hansen ◽  
Qiang Li ◽  
Xiaohua Wei
Keyword(s):  
Climate Variability ◽  
Forest Cover ◽  
Forest Disturbance ◽  
Climatic Variability ◽  
High Flow ◽  
The Body ◽  
Cumulative Effects ◽  
Low Flow ◽  
Mean Flow ◽  
River Watershed

Climatic variability and cumulative forest cover change are the two dominant factors affecting hydrological variability in forested watersheds. Separating the relative effects of each factor on streamflow is gaining increasing attention. This study adds to the body of literature by quantifying the relative contributions of those two drivers to the changes in annual mean flow, low flow, and high flow in a large forested snow dominated watershed, the Deadman River watershed (878 km2) in the Southern Interior of British Columbia, Canada. Over the study period of 1962 to 2012, the cumulative effects of forest disturbance significantly affected the annual mean streamflow. The effects became statistically significant in 1989 at the cumulative forest disturbance level of 12.4% of the watershed area. The modified double mass curve and sensitivity-based methods consistently revealed that forest disturbance and climate variability both increased annual mean streamflow during the disturbance period (1989–2012), with an average increment of 14 mm and 6 mm, respectively. The paired-year approach was used to further investigate the relative contributions to low and high flows. Our analysis showed that low and high flow increased significantly by 19% and 58%, respectively over the disturbance period (p < 0.05). We conclude that forest disturbance and climate variability have significantly increased annual mean flow, low flow and high flow over the last 50 years in a cumulative and additive manner in the Deadman River watershed.

scholarly journals Randomized Double-Blind Trial of the Effects of Humidified Compared with Nonhumidified Low Flow Oxygen Therapy on the Symptoms of Patients

1997 ◽  
Vol 4 (2) ◽  
pp. 76-80 ◽  
Author(s):  
Darcy Andres ◽  
Norma Thurston ◽  
Rollin Brant ◽  
Ward Flemons ◽  
Doreen Fofonoff ◽  
...  
Keyword(s):  
Oxygen Therapy ◽  
Tertiary Care ◽  
University Teaching ◽  
Low Flow ◽  
Subjective Symptoms ◽  
Double Blind ◽  
Significant Group ◽  
Oxygen Administration ◽  
Symptom Scores ◽  
The Difference

OBJECTIVE: To determine the effects of humidified versus nonhumidified low flow oxygen therapy on the subjective symptoms of patients.METHODS: Randomized double-blind clinical trial conducted in a tertiary care university teaching hospital. The sample included medical and surgical in-patients receiving oxygen therapy who met criteria including medical stability, no overt cognitive impairment, English comprehension, voluntary participation and attending physician agreement. Humidified subjects numbered 96 and nonhumidified subjects were 95. The intervention was humidified or nonhumidified oxygen administration using two flowmeters covered by an opaque bag. Patients receiving oxygen therapy longer than three days (first period) were crossed to the alternate treatment (second period) and followed for three more days.RESULTS: Mean symptom scores for nasal dryness were low (mild) for both groups; however, humidification group scores were significantly lower (P=0.018) in the first period than the nonhumidification scores. A corresponding increase in the incidence of nosebleeds was not statistically significant between groups nor were there statistically significant differences between groups for other symptoms/problems. The prevailing trend was decreased incidence of dry mouth, dry throat, headache and chest discomfort during the study.CONCLUSIONS: Although this sample was large enough to expose statistically significant group differences in nasal dryness, the difference was not judged to be clinically significant. The predominant trend was a decrease in symptom scores over time with either treatment. In this group of patients, humidified oxygen does not appear to alleviate subjective symptoms.

scholarly journals On the lack of robustness of hydrologic models regarding water balance simulation: a diagnostic approach applied to three models of increasing complexity on 20 mountainous catchments

2014 ◽  
Vol 18 (2) ◽  
pp. 727-746 ◽  
Author(s):  
L. Coron ◽  
V. Andréassian ◽  
C. Perrin ◽  
M. Bourqui ◽  
F. Hendrickx
Keyword(s):  
Water Balance ◽  
Structural Complexity ◽  
Testing Procedure ◽  
Flow Volume ◽  
Mean Flow ◽  
Hydrologic Models ◽  
Systematic Analysis ◽  
Mountainous Catchments ◽  
Numerical Tools ◽  
Simulation Errors

Abstract. This paper investigates the robustness of rainfall–runoff models when their parameters are transferred in time. More specifically, we propose an approach to diagnose their ability to simulate water balance on periods with different hydroclimatic characteristics. The testing procedure consists in a series of parameter calibrations over 10 yr periods and the systematic analysis of mean flow volume errors on long records. This procedure was applied to three conceptual models of increasing structural complexity over 20 mountainous catchments in southern France. The results showed that robustness problems are common. Errors on 10 yr mean flow volume were significant for all calibration periods and model structures. Various graphical and numerical tools were used to investigate these errors and unexpectedly strong similarities were found in the temporal evolutions of these volume errors. We indeed showed that relative changes in simulated mean flow between 10 yr periods can remain similar, regardless of the calibration period or the conceptual model used. Surprisingly, using longer records for parameters optimisation or using a semi-distributed 19-parameter daily model instead of a simple 1-parameter annual formula did not provide significant improvements regarding these simulation errors on flow volumes. While the actual causes for these robustness problems can be manifold and are difficult to identify in each case, this work highlights that the transferability of water balance adjustments made during calibration can be poor, with potentially huge impacts in the case of studies in non-stationary conditions.

The generation of sound by density inhomogeneities in low Mach number nozzle flows

1975 ◽  
Vol 70 (3) ◽  
pp. 605-622 ◽  
Author(s):  
J. E. Ffowcs Williams ◽  
M. S. Howe
Keyword(s):  
Mach Number ◽  
Free Space ◽  
Approximate Expression ◽  
Low Flow ◽  
Variable Pressure ◽  
Duct Flow ◽  
Mean Flow ◽  
Low Mach Number ◽  
Nozzle Orifice ◽  
Frequency Decomposition

This paper discusses the sound generated when an inhomogeneity in density is convected in a low Mach number steady flow through a contraction in a duct of infinite extent, and also when the inhomogeneity exhausts through a nozzle into free space. The analyses of Candel (1972) and Marble (1973) for the case of duct flow were based on a frequency decomposition of the incident inhomogeneity and cannot adequately deal with sharp-fronted inhomogeneities and entropy spots. However, the practical difficulties of this earlier work can be avoided at low flow Mach numbers by conducting the analysis in terms of an approximate expression for the acoustic Green's function in the manner described by Howe (1975). This method also permits a considerable extension of the range of the earlier investigations to the determination of the sound generated when the inhomogeneity is swept out of a nozzle orifice into free space. It is shown that the acoustic pressure perturbations developed in a duct at a contraction are in general proportional to the fractional difference between the density of the inhomogeneity and that of the mean flow times a typical mean flow pressure level, and are due principally to the fluctuation in thrust accompanying the passage of the inhomogeneity through the region of variable pressure gradient. The pressure waves generated at a nozzle orifice and radiated into free space are O(M0) smaller, where M0 is a mean flow Mach number based on the speed of sound in the jet.

scholarly journals Long-term and Two-period Analysis of Hydrologic Conditions of the South Edisto River

2017 ◽  
pp. 13-20
Author(s):  
Rebecca W. Berzinis
Keyword(s):  
South Carolina ◽  
Low Flow ◽  
Mean Flow ◽  
South Fork ◽  
The South ◽  
Period Analysis ◽  
Daily Streamflow ◽  
Low Flows ◽  
Significant Difference

The U.S. Geological Survey (USGS) long-term daily streamflow record at station 02173000 in Bamberg County, South Carolina on the South Fork Edisto River (Latitude 33°23’35”, Longitude 81°08’00” NAD27) spans from 1932 to 2015 and was used for this study. The Nature Conservancy’s Indicators of Hydrologic Alteration (IHA) software was used to analyze the entire record of hydrologic data as ecologically relevant parameters and to categorize the flows. A two-period analysis was conducted to evaluate whether a significant difference could be observed in historic flow data from 1932–1985 (period one) compared to 1986–2015 (period two). An extreme low flow was defined as an initial low flow below 10% of daily flows for the period. Over the entire 76-year period of record, 51 years had at least one occurrence of extreme low flows. A median of 4 days per year had occurrences of extreme flows in period one in contrast to a median of 60 days per year during period two. Annual precipitation totals were not correlated with the number of days per year with extreme low flows. The two-period analysis showed significant differences between period one and period two for monthly mean flow for February, April, May, and August, as well as for 1-day and 30-day minima and maxima values. The analysis calculated the 7Q10 (the lowest stream flow for seven consecutive days that would be expected to occur once in ten years) at 4.4 cubic meters per second (cms), which was -10.9% different from the most recently published estimate. Results presented in this study have shown that spring and summer flows in the South Fork Edisto are statistically significantly lower in period two compared to period one.

scholarly journals In vitro estimation of the energy loss through turbulence in a porcine aortic valve stenosis model and silicone ascending aorta phantom using backlight particle tracking velocimetry

2021 ◽  
Vol 42 (Supplement_1) ◽  
Author(s):  
M Chiarelli ◽  
S F De Marchi ◽  
D Obrist ◽  
E Buffle
Keyword(s):  
Left Ventricle ◽  
Aortic Stenosis ◽  
Energy Loss ◽  
Particle Tracking Velocimetry ◽  
Ascending Aorta ◽  
Low Flow ◽  
Mean Flow ◽  
Flow Rates ◽  
Stenosis Severity

Abstract Introduction Patients suffering from low-flow, low-gradient aortic stenosis present a decreased stroke volume due to decreased contraction or relaxation function of the left ventricle. As a low stroke volume tends to cause a low transvalvular flow, transvalvular pressure gradient (TVPG) and effective orifice area, the clinician cannot rely on those parameters with confidence for the evaluation of aortic stenosis severity. Hence new diagnostic parameters have to be developed. Energy loss through turbulence associated with aortic stenosis represented the wasted left ventricle work. Currently, echocardiographic measurement of the turbulence intensity is not validated for clinical evaluations of aortic stenosis. Methods Two porcine aortic valves were harvested and inserted in a flow loop that replicates the pulsatile flow of the heart. A stiffening of the valves was achieved by treating them with formaldehyde. The stiffening was externally confirmed by a custom-made force-displacement device quantifying the rigidity of the leaflet yielding two stiffness grades per valve. Each valve was tested under three different mean flow rates (1, 2.5, and 4 l/min) at each of the two stiffness grades. Moreover the pressure in the left ventricle chamber and in the aortic chamber was recorded to calculate the TVPG. Particle tracking velocimetry measurements into the transparent silicone ascending aorta phantom allowed the computation of the turbulent kinetic energy (TKE), to evaluate the energy loss due to turbulence. Results We could confirm the enhanced rigidity of the valve leaflets with our custom device (data not shown) and measure a consistent increase in TVPG across all mean flow rates between the two stiffness grades. Moreover, an explicit increase of the TKE in the aortic phantom could be measured after the stiffening process (73.1% under 1 l/min, and 43% under both 2.5 and 4 l/min). In addition, a good correlation (R = 0.86) between the mean TVPG and the TKE was found. Conclusions This project demonstrated the possibility of quantifying the energy loss attributed to turbulence for porcine valves in vitro for native and added stiffness grade. This project lays the foundation for the development of a new diagnostic tool for the assessment of stenosis severity in patients with low-flow, low-gradient aortic stenosis in cardiac imaging tool such as echocardiography. FUNDunding Acknowledgement Type of funding sources: None. TVPG and its correlation with TKE Intensity graphs of the TKE

scholarly journals Topography significantly influencing low flows in snow-dominated watersheds

2017 ◽  
Author(s):  
Qiang Li ◽  
Xiaohua Wei ◽  
Xin Yang ◽  
Krysta Giles-Hansen ◽  
Mingfang Zhang ◽  
...  
Keyword(s):  
Regression Models ◽  
Low Flow ◽  
Mean Flow ◽  
Slope Length ◽  
Low Flows ◽  
Slope Length Factor ◽  
High Flows ◽  
Flow Variables ◽  
Characterization Index

Abstract. Watershed topography plays an important role in determining the spatial heterogeneity of ecological, geomorphological, and hydrological processes. Few studies have quantified the role of topography on various flow variables. In this study, 28 watersheds with snow-dominated hydrological regimes were selected with daily flow records from 1989 to 1996. The watersheds are located in the Southern Interior of British Columbia, Canada and range in size from 2.6 to 1,780 km2. For each watershed, 22 topographic indices (TIs) were derived, including those commonly used in hydrology and other environmental fields. Flow variables include annual mean flow (Qmean), Q10%, Q25%, Q50%, Q75%, Q90%, and annual minimum flow (Qmin), where Qx% is defined as flows that at the percentage (x) occurred in any given year. Factor analysis (FA) was first adopted to exclude some redundant or repetitive TIs. Then, stepwise regression models were employed to quantify the relative contributions of TIs to each flow variable in each year. Our results show that topography plays a more important role in low flows than high flows. However, the effects of TIs on flow variables are not consistent. Our analysis also determines five significant TIs including perimeter, surface area, openness, terrain characterization index, and slope length factor, which can be used to compare watersheds when low flow assessments are conducted, especially in snow-dominated regions.

Hemodynamics of coronary artery stenosis

1984 ◽  
Vol 62 (1) ◽  
pp. 59-69 ◽  
Author(s):  
Alan Y. K. Wong ◽  
G. A. Klassen ◽  
David E. Johnstone
Keyword(s):  
Coronary Artery ◽  
Flow Rate ◽  
Pressure Loss ◽  
Coronary Flow ◽  
Cardiac Cycle ◽  
Low Flow ◽  
Published Data ◽  
Mean Flow ◽  
Additional Pressure ◽  
Coronary Pressure

A model is proposed to study the hemodynamics of various types of coronary stenosis. The model coronary artery is assumed to be an elastic tapered tube. A progressive degree of concentric and eccentric stenoses are studied. Measured pulsatile coronary pressure, flow, and intramyocardial pressure are used as input data to calculate the pressure and flow velocities at different locations of the artery. The simulation yields results that agree well with published data in dog experiments, and those from human stenotic coronary arteries. The present model shows that in a cardiac cycle, the overall hydraulic resistance owing to a specific stenosis tends to be flow independent at low flow rate but increases linearly with flow at higher coronary flow. This flow independent resistance increases with progressive stenosis. At low flow, the mean coronary flow in a cardiac cycle is relatively constant with stenoses up to 80%, but decreases dramatically with further increase in the degree of narrowing. At high resting flow rate, this mean flow is markedly reduced at much smaller degrees of constriction. The simulated pressure velocity relation of poststenotic dilatation indicates an additional pressure loss at the distal end of the stenosis, but the calculated resistance to flow is actually lessened. While stenosis length increases pressure loss and resistance to flow, its effect on mean flow appears disproportionally insignificant. Eccentric lesions appear to be more detrimental than concentric ones as they produce additional pressure loss and greater resistance across the coronary artery lesion.

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