Model of stationary gas network

Modern problems of quantitative risk assessment require a development of more sophisticated types of so-called formation models. The formation models give all the information about an accidental leakage due the depressurization needed for quantitative estimation of the dangerous substances accumulating in the environment and further calculation of impact factors on humans, buildings etc. Common type of depressurization is a release of gaseous substances throughout the accidental hole on the surface of apparatus or pipeline. The pipeline connecting two vessels and a hole occurred on the pipeline as well as streams of vapour phase moving inside the pipelines and throughout the hole is a classical example of graph theory transport network problem. Thereby the model of stationary gas network based on equations of subsonic and choked adiabatic flow (for ideal gas) with accounting of mixing processes has been proposed. The solution with applying of graph theory, linear algebra and numerical analysis has been found.The gas net is represented as an oriented graph with nodes as a pressure-points and lines as pipelines. Case of incorrect estimation of flows directions has been studied and the problem of solving algorithm’s self-correction has been arisen. The method of incidence matrix correction during solving process has been developed and applied. The Newton’s method of non-linear equations system solving has been applied and specific method of Jacoby matrix correction has been developed.The behaviour of gas network model has been studied on example of a hydrocarbons’ mixture leakage from an accidental hole on the pipeline connecting two vessels. Results of numerical simulation experiments showed good agreement of model with basic laws of ideal gas adiabatic flow movement and gas network system in general. The directions of flows were in agreement with pressures’ differences on the lines as well as material and energy conservation laws have been observed. Model can be applied in numerical risks analysis for modelling of accidental processes of gaseous substances leaks as well as for the transport problems of chemical technology or educational purposes.

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Biofilm formation by clinically isolated Staphylococcus Aureus from India

The Journal of Infection in Developing Countries ◽

10.3855/jidc.10671 ◽

2018 ◽

Vol 12 (12) ◽

pp. 1062-1066 ◽

Cited By ~ 1

Author(s):

Alasthimannahalli Gangadhara Triveni ◽

Mendem Suresh Kumar ◽

Chavadi Manjunath ◽

Channappa T Shivannavar ◽

Subhaschandra M Gaddad

Keyword(s):

Staphylococcus Aureus ◽

Congo Red ◽

Biofilm Formation ◽

Quantitative Estimation ◽

Microtiter Plate ◽

Clinical Samples ◽

Specific Method ◽

Qualitative And Quantitative ◽

Etiological Agents

Introduction: Staphylococcal biofilms are prominent cause for acute and chronic infection both in hospital and community settings across the world. Current study explores biofilm formation by Staphylococcus aureus isolates from clinical samples by different methods. Methodology: Standard techniques used for the characterization of S.aureus. Qualitative and quantitative biofilm formation was assessed by Congo red Agar, Tube and Microtiter plate methods. Results: A total of 188 clinical isolates of S.aureus were screened for biofilm formation and 72 (38.29%) of them were found to be biofilm producers, 34 (18.08%) strong, 38 (20.21%) moderate. The remaining 116 (61.7%) were weak/ non biofilm producers. Maximum biofilm formers were recorded in pus samples (39.06%), followed by isolates from blood (38.23%) and urine (34.61%). Statistical analysis for the formation of biofilm indicated that Microtiter plate method is the most sensitive and specific method for screening biofilm production. Conclusions: Biofilm formation is one of the influential virulence factor in staphylococcal pathogenesis and persistence. Microtiter plate and Congo red agar remain as reliable methods for the qualitative and quantitative estimation of biofilm formation. Monitoring of biofilm formation in various etiological agents will help in determining the severity of infection.

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The Influence of Real Gas Properties on Predictions of Static and Rotordynamic Properties of Annular Seals for Injection Compressors

Volume 5: Turbo Expo 2007 ◽

10.1115/gt2007-27293 ◽

2007 ◽

Author(s):

Yoon-Shik Shin ◽

Dara W. Childs

Keyword(s):

Energy Equation ◽

Control Volume ◽

Ideal Gas ◽

Running Speed ◽

Real Gas ◽

Adiabatic Flow ◽

Rotordynamic Coefficients ◽

Ideal Gas Law ◽

Piston Seal ◽

Gas Properties

Predictions are presented for an annular gas seal that is representative of the division-wall seal of a back-to-back compressor or the balance-piston seal of an in-line compressor. A 2-control-volume bulk-flow model is used including the axial and circumferential momentum equations and the continuity equations. The basic model uses a constant temperature prediction (ISOT) and an ideal gas law as an equation of state. Two variations are used: adding the energy equation with an ideal gas law (IDEAL), and adding the energy equation with real gas properties (REAL). The energy equations assume adiabatic flow. The ISOT model has been used for prior calculations. Concerning predictions of static characteristics, the calculated mass leakage rate was, respectively, 9.46, 9.55 and 7.87 kg/s for ISOT, IDEAL, and REAL. For rotordynamic coefficients, predicted effective stiffness coefficients are comparable for the models at low excitation frequencies. At running speed, REAL predictions are roughly 40% lower than ISOT, which could results in lower predicted critical speeds. Predicted effective damping coefficients are also generally comparable. REAL and IDEAL predictions for the cross-over frequency is approximately 20% lower than ISOT. REAL predictions for effective damping are modestly lower in the frequency range of 40 to 50% of running speed where higher damping values are desired.

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Calculating the Time of Adiabatic Flow of an Ideal Gas from a Constant Volume Reservoir Using Relative Parameters

Tyumen State University Herald Physical and Mathematical Modeling Oil Gas Energy ◽

10.21684/2411-7978-2018-4-2-94-104 ◽

2018 ◽

Vol 4 (2) ◽

pp. 94-104 ◽

Cited By ~ 1

Author(s):

Vadim V. Tarasov

Keyword(s):

Ideal Gas ◽

Constant Volume ◽

Adiabatic Flow

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Calculation of the Adiabatic Flow Time of an Ideal Gas from a Constant Volume Reservoir, Accounting for the Process of Opening the Exhaust Valve

Tyumen State University Herald Physical and Mathematical Modeling Oil Gas Energy ◽

10.21684/2411-7978-2018-4-1-80-92 ◽

2018 ◽

Vol 4 (4) ◽

pp. 80-92

Author(s):

Vadim V. Tarasov

Keyword(s):

Ideal Gas ◽

Flow Time ◽

Constant Volume ◽

Exhaust Valve ◽

Adiabatic Flow

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Problems of quantitative estimation of excretory kidney function based on creatinin

Nephrology (Saint-Petersburg) ◽

10.36485/1561-6274-2020-24-4-102-109 ◽

2020 ◽

Vol 24 (4) ◽

pp. 102-109

Author(s):

O. A. Nagibovich ◽

D. A. Shipilova ◽

N. A. Shchukina ◽

A. E. Trandina

Keyword(s):

Serum Creatinine ◽

Measurement Errors ◽

Quantitative Estimation ◽

Reference Sample ◽

Specific Method ◽

Specific Patient ◽

True Value ◽

Continue Research ◽

The Relationship ◽

Analytical Errors

This review presents the possibility of using serum creatinine as an endogenous indicator of the functional state of the kidneys. The results of scientific research are analyzed, which shows the information content of the use of this indicator for assessing glomerular filtration rate (GFR). The features of laboratory methods for determining serum creatinine are considered. Particular attention is paid to information about the errors and variability of measurements of standardized methods obtained in laboratories of different countries. In addition to the physiological reasons that make serum creatinine an imperfect marker for GFR, there are analytical measurement errors, which, in turn, can also distort true results. Since the relationship between serum creatinine and GFR is hyperbolic, analytical errors will affect not only the accuracy of the calculation equations based on it. The introduction of standardization of routine methods for measuring serum creatinine from a reference sample improved the assessment of GFR by reducing the bias of the results of measuring creatinine from its true value. To increase the accuracy and reliability of standardized methods, it is necessary to continue research in this direction. In real clinical practice, all the limitations and assumptions of a specific method of measuring creatinine should be taken into account in order to avoid incorrect interpretation of the results when assessing the functional ability and staging of chronic kidney disease. For prospective observation of a specific patient, the same GFR calculation formula and the same method for measuring serum creatinine should be used.

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Self-similar adiabatic flow headed by a magnetogasdynamic cylindrical shock wave in a rotating non-ideal gas

Geophysical & Astrophysical Fluid Dynamics ◽

10.1080/03091920701298112 ◽

2007 ◽

Vol 101 (2) ◽

pp. 155-168 ◽

Cited By ~ 17

Author(s):

J. P. Vishwakarma ◽

Anil Kumar Maurya ◽

K. K. Singh

Keyword(s):

Shock Wave ◽

Ideal Gas ◽

Cylindrical Shock Wave ◽

Adiabatic Flow ◽

Self Similar

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Calculating the integral characteristics for a compressible stream of an ideal gas in the case of adiabatic flow

Journal of Engineering Physics ◽

10.1007/bf00828525 ◽

1969 ◽

Vol 16 (4) ◽

pp. 461-466

Author(s):

A. F. Gandel'sman ◽

B. A. Kader ◽

G. G. Katsnel'son

Keyword(s):

Ideal Gas ◽

Adiabatic Flow ◽

Integral Characteristics

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Coupling geochemical and isotopic tracers (δ18O, δ2H and 87Sr/86Sr) to quantify groundwater mixing in carbonate environment

10.5194/egusphere-egu21-12990 ◽

2021 ◽

Author(s):

Thibaut Garin ◽

Bernard Ladouche ◽

Bruno Arfib ◽

Benoit Dewandel ◽

Julio Goncalves

Keyword(s):

Quantitative Estimation ◽

Groundwater Resources ◽

Mixing Processes ◽

Isotopic Tracers ◽

Dye Tracing ◽

Rock Interaction ◽

Marine Influence ◽

End Members ◽

Different Origins

Carbonate aquifers are known as a major source for drinking water in the Mediterranean region. Therefore, qualitative and quantitative estimation of the groundwater resource are crucial, especially in area with densely populated areas.In this study, geochemical and isotopic tracers (&#948;18O, &#948;2H and 87Sr/86Sr) have been used to discriminate different origins of groundwater and evaluate water-mass mixing in a Mediterranean carbonate environment. The case study, located in south-eastern France, offers an attractive geological context to explore strontium isotopic tracers: trias to cretaceous carbonate rocks, that have been eroded and locally resedimented in fluvial deposits during Oligocene extension and Quaternary periods. Moreover, many karst features act as sinking zones, generating fast infiltration. The 500 km&#178; zone investigated has also a large range of elevation, from the sea to 1148m, giving an expected significant contrast in water isotopes. Monthly water samples have been collected in-situ for two years on ground and surface waters, in rivers, boreholes as well as karstic springs. Monthly rainwater samples provide the isotopic signal of the recharge at two distinct elevations and distance from the sea.The hydrogeochemical signatures allow to discriminate the end-members of two main waterbodies as well as a slight marine influence on one borehole. Nitrates concentrations (NO3-) highlight anthropogenic influence on groundwater resources. A multi-tracer approach taking in account water-rock interaction, mixing processes and recharge, coupled with hydrogeological conditions and dye-tracing tests, leads to a conceptual model of this complex hydrosystem.

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