Recent Advances in Scale Prediction: Approach and Limitations

SPE Journal ◽  
2019 ◽  
Vol 24 (05) ◽  
pp. 2209-2220 ◽  
Author(s):  
Amy T. Kan ◽  
Joey (Zhaoyi) Dai ◽  
Guannan Deng ◽  
Harouaka Khadouja ◽  
Yi-Tsung Lu ◽  
...  
Keyword(s):  
Ph Value ◽  
Saturation Index ◽  
Ultrahigh Pressure ◽  
Quality Data ◽  
Mixed Electrolytes ◽  
Computer Algorithms ◽  
Estimation Errors ◽  
Mean Values ◽  
Temperature And Pressure ◽  
Prediction Approach

Summary Numerous saturation indices and computer algorithms have been developed to determine whether, when, and where scale will form. However, scale prediction can still be challenging because the predictions from different models often differ significantly at extreme conditions. Furthermore, there is a great need to accurately interpret the partitioning of water (H2O), carbon dioxide (CO2), and hydrogen sulfide (H2S) between different phases, as well as the speciations of CO2 and H2S. This paper summarizes current developments in the equation-of-state (EOS) and Pitzer models to accurately model the partitioning of H2O, CO2, and H2S in hydrocarbon/aqueous phases and the aqueous ion activities at ultrahigh-temperature, ultrahigh-pressure, and mixed-electrolytes conditions. The equations derived from the Pitzer ion-interaction theory have been parameterized by regression of more than 10,000 experimental data from publications over the last 170-plus years using a genetic algorithm on the supercomputer DAVinCI at Rice University. With this new model, the 95% confidence intervals of the estimation errors for solution density are within 4×10–4 g/cm3. The solubility predictions of CO2 and H2S are accurate to within 4%. The saturation-index (SI) mean values for calcite (CaCO3), barite (BaSO4), gypsum (CaSO4·2H2O), anhydrite (CaSO4), and celestite (SrSO4) are accurate to within ±0.1—and for halite the values are within ±0.01—most of which are within experimental uncertainties. This model accurately defines the pH value of the production tubing at various temperature and pressure regimes and the risk of H2S exposure and corrosion. Furthermore, our model is able to predict the density of soluble chloride and sulfate (SO42−) salt solutions within ± 0.1% relative error. The ability to accurately predict the density of a given solution at temperature and pressure allows one to deduce when freshwater breakthrough will occur. In addition, accurate predictions can only be reliable with accurate data input. The need to improve the accuracy of scale prediction with quality data will also be discussed.

Design Nomographs of Compression Helical Springs for Predetermined Reliability Levels

1981 ◽  
Vol 103 (2) ◽  
pp. 268-273
Author(s):  
My Dao Thien ◽  
M. Massoud
Keyword(s):  
Probabilistic Approach ◽  
Design Procedure ◽  
Axial Loading ◽  
Geometric Parameters ◽  
Computer Algorithms ◽  
Mean Values ◽  
Helical Springs ◽  
Reliability Level ◽  
Classical Design ◽  
Mission Success

This paper discusses a probabilistic approach for the design of Compression Closely Coiled Helical Springs subjected to periodic axial loading. The classical design procedure results in deterministic geometric parameters with tolerances normally chosen according to standards without due regard to their effects on the mission success as normally expressed by a reliability level. With the proposed design procedure, the engineer can specify nominal mean values for the geometric parameters and their tolerances according to a predetermined reliability level. Design nomographs are presented to help the engineer, in the early stages of design, to choose between many alternatives. Computer algorithms can easily be written to verify the final or optimum design.

Study on Advanced Oxidation of Cafeteria Wastewater Using Fenton Reagent

2012 ◽  
Vol 424-425 ◽  
pp. 1322-1325
Author(s):  
Rong Jun Su ◽  
Peng Wang ◽  
Li Ming Jiang
Keyword(s):  
Treatment Process ◽  
Biological Process ◽  
Ph Value ◽  
Processing Conditions ◽  
Fenton Reagent ◽  
Land Occupation ◽  
Orthogonal Experiments ◽  
Reagent Treatment ◽  
Temperature And Pressure ◽  
Land Space

Fenton reagent was selected as oxidizers for the oxidation and degradation of cafeteria wastewater. The treatment effects were evaluated by the changes of COD and BOD5 parameters. The effects of Fenton reagent ratio, dosage of FeSO4•7H2O and pH value on wastewater treatment under normal temperature and pressure were investigated, the oxidation regularity is initially discovered as well. Orthogonal experiments were designed to optimize the processing conditions based on the single affected factor. The optimized controlling conditions for Fenton reagent treatment process is FeSO4•7H2O=1mmol/L, pH=3, H2O2/Fe2+=3.5:1, reaction time=60min. With Fenton reagent treatment the COD removal ratio was raised up to 94%. Compared with biological process, it saved land occupation and was more suitable for regions which lacked of land space.

Gas bubble induced scalings in geothermal systems

2021 ◽  
Author(s):  
Lilly Zacherl ◽  
Thomas Baumann
Keyword(s):  
Ph Value ◽  
Saturation Index ◽  
Gas Bubbles ◽  
Gas Bubble ◽  
Geothermal Systems ◽  
Injection Wells ◽  
Term Operation ◽  
Maintenance Schedule ◽  
Local Experience ◽  
Maintenance Schedules

<p>Scalings in geothermal systems are affecting the efficiency and safety of geothermal systems. An operate-until-fail maintenance scheme might seem appropriate for subsurface installations where the replacement of pumps and production pipes is costly and regular maintenance comprises a complete overhaul of the installations. The situation is different for surface level installations and injection wells. Here, monitoring of the thickness of precipitates is the key to optimized maintenance schedules and long-term operation.</p><p>A questionnaire revealed that operators of geothermal facilities start with a standardized maintenance schedule which is adjusted based on local experience. Sensor networks, numerical modelling and predictive maintenance are not yet applied. In this project we are aiming to close this gap with the development of a non-invasive sensor system coupled to innovative data acquisition and evaluation and an expert system to quantitatively predict the development of precipitations in geothermal systems and open cooling towers.</p><p>Previous investigations of scalings in the lower part of production pipes of a geothermal facility suggest that the disruption of the carbonate equilibrium is triggered by the formation of gas bubbles in the pump and subsequent stripping of CO<sub>2</sub>. Although small in it's overall effect on pH-value and saturation index, significant amounts of precipitates are forming at high volumetric flow rates. To assess the kinetics of gas bubble induced precipitations laboratory experiments were run. The experiment addresses precipitations at surfaces and at the gas bubbles themselves.</p>

scholarly journals Combining F-Scan and GAITRite® for use in Clinical Gait Analysis: A Validation Study.

2020 ◽  
Author(s):  
Stephanie Speight ◽  
Selina Reidy ◽  
John Stephenson ◽  
Sarah Reel
Keyword(s):  
Gait Analysis ◽  
Correlation Coefficient ◽  
Intraclass Correlation Coefficient ◽  
Intraclass Correlation ◽  
Cost Effective ◽  
Quality Data ◽  
Concordance Correlation Coefficient ◽  
Concordance Correlation ◽  
Mean Values ◽  
Level Of Agreement

Abstract BackgroundClinical gait analysis is widely used to aid the assessment and diagnosis of symptomatic pathologies. Equipment based analysis provides clinicians with a more comprehensive assessment using pressure systems such as F-scan, or analysis of the spatial-temporal parameters of gait using GAITRite. There are systems however such as Strideway™ that can measure these parameters simultaneously, but can be expensive. This study aimed to determine whether standalone systems can be used collectively while still providing quality data, as a cost-effective alternative.MethodsTwenty-six participants walked on a standard floor and a GAITRite walkway, three times wearing the F-Scan system. Mid gait protocols were utilised by analysing the contact pressure of the 2 nd metatarsophalangeal joint of the third, fifth and seventh step from each walk. The Bland-Altman method was used to determine a level of agreement between the two surfaces, using mean values from all walks of all participants who successfully completed all required walks. The intraclass correlation coefficient and Lin’s concordance correlation coefficient were calculated as indices of reliability.ResultsThe intraclass correlation coefficient was calculated to be 0.991 and Lin’s concordance correlation coefficient for the data was calculated to be 0.956, indicating very good reproducibility.ConclusionsThe level of agreement in plantar pressures observed on the two surfaces was very high, suggesting that it is feasible to use F-Scan and GAITRite® together in a clinical setting, as an alternative to other less cost-effective standalone systems.

scholarly journals ELECTROENDOSMOSIS THROUGH MAMMALIAN SEROUS MEMBRANES

1925 ◽  
Vol 7 (3) ◽  
pp. 389-413 ◽  
Author(s):  
Stuart Mudd
Keyword(s):  
Ph Value ◽  
Ion Concentration ◽  
Time Interval ◽  
Fat Cells ◽  
Post Mortem ◽  
Small Shift ◽  
Hydrogen Ion Concentration ◽  
Mean Values ◽  
Reversal Point ◽  
The Mean

It is shown that when a mammalian serous membrane bathed in dilute buffer is traversed by an electric current, liquid is caused to stream through the membrane toward the cathode when the pH value of the buffer is on the alkaline side of a certain critical hydrogen ion concentration. Streaming is toward the anode on the acid side of the reversal point. Simple means for studying this electroendosmosis quantitatively are described. The mean values of the reversal points in all cases studied with the present buffers lie between pH = 4.3 and 5.3. The membranes studied have been the mesentery of the living and dead animal, and the parietal pericardium and pleura, post mortem. The membranes of dogs, cats, rabbits, and two human pericardia have been studied. All these membranes are essentially sheets of connective tissue, bearing blood vessels, lymphatics, and nerves, and in some instances fat cells, and lined on each surface by a single layer of pavement mesothelial cells. Intercellular fibers form the major bulk of the lean membranes. These are predominantly collagenous except in the pleural region used, in which elastin fibers are present in large proportion. By using buffers alternately more acid or more alkaline than the reversal point, the direction of liquid flow across any given membrane site could be reversed an indefinite number of times. The time interval required is only that taken by the requisite manipulation in changing buffers and making the runs. The mean values of the reversal points for the several membranes when bathed in hypotonic, unbalanced buffer and in isotonic, physiologically balanced buffers showed only small and inconstant differences. The fat and lean pericardia similarly showed small difference in the positions of the mean reversal points. The apparent reversal points for the mesenteries of living animals proved to be lower than those for the mesenteries post mortem. This low value in the animals with functioning circulation is interpreted as essentially due to admixture with the buffers of buffer salts from the blood. Clear differences between the reversal points of the membranes in the first compared with later hours or days post mortem were not detected, with the possible exception of a small shift toward the acid range of the fat pericardium reversal points estimated several days post mortem. The reversal points with cat membranes were somewhat lower (more acid) than those of the dog. The approximate mean reversal points found with the citrate-phosphate buffers used were as follows: For mesenteries of living animals pH = 4.4; for mesenteries, post mortem, pH = 4.8; for cat pleuræ, post mortem, pH = 4.3; for dog pleuræ, post mortem, pH = 5.0; for lean and fat pericardia, post mortem, pH = 5.1. The mean reversal point of the two human pericardia was about pH = 5.0. Reversal points determined with buffers containing only monovalent anions are somewhat higher (less acid), as will be shown later. The bearing of these data on the question of the chemical composition of the surfaces of the fat cells of the serous membranes is discussed. Briefly, it is believed that proteins are probably present in important amount in these cell surfaces.

scholarly journals Changes in selected physicochemical parameters of breast muscles of geese from Polish conservation flocks depending on duration of the post slaughter period

2008 ◽  
Vol 51 (3) ◽  
pp. 255-265 ◽  
Author(s):  
A. Okruszek ◽  
J. Książkiewicz ◽  
J. Wołoszyn ◽  
G. Haraf ◽  
A. Orkusz ◽  
...  
Keyword(s):  
Genetic Resources ◽  
Physicochemical Parameters ◽  
Ph Value ◽  
The Other ◽  
Mean Values ◽  
Qualitative Traits ◽  
Ph Values ◽  
Colour Parameters ◽  
The Mean

Abstract. In four Polish conservative flocks of Suwałki (Su), Kartuzy (Ka), Kielce (Ki) and Subcarpathian (Sb) geese, registered by FAO as domestic genetic resources the mean values of qualitative traits of breast muscles (pH15', pH30', pH45', pH24h; colour parameters: L*15', L*30', L*45', L24h, a*15', a*30', a*45', a*24h, b*15', b*30', b*45', b*24h and conductivity: EC45', EC3h, EC24h) were determined. The experimental flocks showed significant variations in the investigated parameters. The Kartuzy goose breast muscles were characterized by higher values of pH15' (6.74), pH30' (6.62), pH45' (6.56) and b*15' parameter (0.80) in comparison with the remaining flocks. Moreover, these muscles had the lowest pH24h (5.65) and values of L* parameter (L*15', L*30', L*45' and L*24h) and EC45' (3.23 mS/cm). The pH value and L* and a* parameters (except L*24h and a*24h) of the analysed flocks were decreasing, and conductivity increasing together with the time post slaughter, and the rate of changes depended on the birds’ origin. Greater differences between pH values, measured 15 min and 24 h after slaughter were stated in breast muscles from Ka (1.09) and Su (0.90) geese than from the other two flocks investigated (Ki – 0.74; Sb – 0.58). The highest increase in conductivity (from EC45' to EC24h) was affirmed in Ka and Ki muscles (3.84 mS/cm) and the lowest in breast muscles of Sb geese (2.72 mS/cm).

scholarly journals ANALISIS KONDISI LAMUN (SEAGRASS) DI PERAIRAN PULAU PRAMUKA, KEPULAUAN SERIBU

2015 ◽  
Vol 13 (1) ◽  
pp. 22-32
Author(s):  
Septi Dwi Fajarwati ◽  
Asma Irma Setianingsih ◽  
Muzani Muzani
Keyword(s):  
Water Quality ◽  
Community Structure ◽  
Ph Value ◽  
Secondary Data ◽  
Quality Analysis ◽  
Quality Data ◽  
Primary Data ◽  
Seagrass Habitat ◽  
Percentage Cover ◽  
Water Quality Data

ABSTRACT This research aims to analyze the condition of seagrass ecosystem to see water quality data of the seagrass habitat and percentage cover of seagrass in the waters of the Pramuka Island, Seribu Islands. The research was conducted over two months from October to November 2014.This research used a descriptive method with field survey approach. The population in this study is the seagrass in Waters Pramuka Island. Determining the location with purposive sampling of the sampling is divided into three stations is North, East and South. Data collection techniques include primary data and secondary data. Primary data is data of seagrass (type, percentage cover and density of seagrass) and data of seagrass habitat environmental parameters (water temperature, current speed, brightness, depth, salinity, substrate, TSS, DO, pH) were obtained by direct measurement in the field, while secondary data include the general state of the research sites. Data analysis techniques used in this study using analysis of community structure of seagrass and water quality analysis. The results showed that seagrass species found in the Pramuka Island there are 6 types of seagrass Cymodocea rotundata, Cymodocea serrulata, Enhalus acoroides, Halophila ovalis, Halodule uninervis, Thalassia hemprichii. Conditions of seagrass in the waters of the Pramuka Island included into the category of less healthy-poor seagrass. At station 1 percentage by 31% classified seagrass less healthy conditions, while the other two stations are stations 2 and 3 belong to the category of the poor condition of seagrass, with each percentage cover of seagrass 19.4% and 20.3%. Of all water quality parameters measured, all the parameters are still in normal circumstances, but there are some parameters whose value is high at some stations TSS and pH value is high at station 2 with a value of TSS 18 mg/l and a pH value of 8.2. Water quality and seagrass communities in station 1 is still in good condition for the growth of seagrass, because at this station is an unspoiled area away from human activity, while the stations 2 and 3 have undergone changes in community structure of seagrass because at this station has several anthropogenic activities that disrupt the lives of seagrass, mostly from human activities such as domestic sewage and hoarding/reclamation, which affects the condition of seagrass at station 2 and 3 are poor seagrass. Keyword: Seagrass, Water Quality, Pramuka Island

scholarly journals Nutritional and energetic value of hard cheese

2018 ◽  
Vol 34 (2) ◽  
pp. 217-227
Author(s):  
Anka Popovic-Vranjes ◽  
Snezana Paskas ◽  
Marija Jevtic ◽  
Anka Kasalica ◽  
Branislava Belic ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Milk Fat ◽  
Ph Value ◽  
Saturated Fatty Acids ◽  
Dairy Product ◽  
Essential Amino Acids ◽  
Cow Milk ◽  
Mean Values ◽  
Microbiological Parameters ◽  
Hard Cheese

Insufficient intake of dairy product, especially of hard cheese, in Serbia is a nutritional problem of concern. It is caused not only by income but also with low commercial availability of the product and consumer knowledge and preferences. This study assesses nutritional and microbiological parameters of hard cheese made from pasteurized cow milk. Standard chemical analyzes were performed and cheese were analyzed on the 1st, 30th and 60th days of ripening. The following microbiological indicators were monitored: Listeria monocytogenes, coagulase-positive Staphylococci, Escherichia coli and Enterobacteriaceae. Furthermore, ripened cheeses were analyzed on amino and fatty acid profile. All cheese samples presented satisfactory microbiological and nutritional characteristics for most of the assessed parameters. Ripened cheese contained on the average 29.08% milk fat, 25.29% proteins, 0.98% lactose and pH value was 5.23. The fat content on dry matter basis (FDM) and moisture in non fat substance (MNFS) were 49.11% and 55.84 %, respectively. The energy value of cheeses amounted to 366.80 kcal /1523.22 kJ. Mean values of fatty acids content (g/100 g) showed that cheese most contained saturated fatty acids, following with monounsaturated and polyunsaturated fatty acids: 66.92%, 30.13% and 2.95%, respectively. The most common essential amino acids were leucine, lysine and isoleucine. This paper confirms that hard cheese is an important source of valuable nutrients and energy and should possess priority in human diet.

scholarly journals Patients’ self-assessed sleep as a nursing tool during hospital care: A pilot study

2020 ◽  
Vol 40 (3) ◽  
pp. 123-129
Author(s):  
Linda Gellerstedt ◽  
Monica Rydell Karlsson ◽  
Jörgen Medin ◽  
Maria Kumlin
Keyword(s):  
Pilot Study ◽  
Hospital Care ◽  
Response Rate ◽  
High Response Rate ◽  
Assessment Tools ◽  
Quality Data ◽  
Mean Values ◽  
Sleep Assessment ◽  
Centered Care ◽  
Different Dimensions

Sleep in hospital is considered a challenge from both a patient and a nursing perspective. To enable nurses to promote patients’ sleep during hospital care it is essential to have valid, reliable and useful sleep assessment tools at hand. The aim of the present study was to evaluate and compare the outcomes of objectively estimated sleep and self-reported sleep quality. Data were collected through continuous wrist-worn actigraphy and completion of the Richards–Campbell Sleep Questionnaire (RCSQ) in a pilot study on 25 patients during hospital care. A correlation between mean values for the two assessments was shown for the second night but not for the third night of assessment, and it was concluded that the two assessments might capture different dimensions of sleep. Furthermore, based on a high response rate and an evident feasibility in a nursing context the RCSQ may facilitate person-centered care.

Effects of sampling frequency on estimation accuracies of annual loadings for water quality parameters in different sized watersheds

2020 ◽  
Vol 55 (3) ◽  
pp. 261-277
Author(s):  
Lin Gao ◽  
Junyu Qi ◽  
Sheng Li ◽  
Glenn Benoy ◽  
Zisheng Xing ◽  
...  
Keyword(s):  
Water Quality ◽  
Suspended Solids ◽  
Nitrate Nitrogen ◽  
Sampling Frequency ◽  
Quality Parameters ◽  
Water Quality Parameters ◽  
Quality Data ◽  
Estimation Errors ◽  
Water Quality Data ◽  
Novel Approach

Abstract Potential errors or uncertainties of annual loading estimations for water quality parameters such as suspended solids (SS), nitrate-nitrogen (NO3-N), ortho-phosphorus (Ortho-P), potassium (K), calcium (Ca), and magnesium (Mg) can be greatly affected by sampling frequencies. In this study, annual loading estimation errors were assessed in terms of the coefficient of variation, relative bias, and probability of potential errors that were estimated with statistical samples taken at a series of sampling frequencies for a watershed in northwestern New Brunswick, Canada, and one of its sub-watersheds. Results indicate that annual loading estimation errors increased with decreasing sampling frequency for all water quality parameters. At the same sampling frequencies, the estimation errors were several times greater for the smaller watershed than those for the larger watershed, possibly due to the flushing nature of streamflows in the smaller watershed. We also found that low sampling frequency tended to underestimate the annual loadings of water quality parameters dominated by stormflow events (SS and K) and overestimate water quality parameters dominated by baseflow (Mg and Ca). These results can be used by hydrologists and water quality managers to determine sampling frequencies that minimize costs while providing acceptable estimation errors. This study also demonstrates a novel approach to assess potential errors when analyzing existing water quality data.

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