scholarly journals STRUCTURAL LEVELS OF THE NUCLEATION AND GROWTH OF FATIGUE CRACK IN 17MN1SI STEEL PIPELINE AFTER LONG-TERM SERVICE

Transport ◽  
2015 ◽  
Vol 30 (1) ◽  
pp. 15-23 ◽  
Author(s):  
Pavlo Maruschak ◽  
Sergey Panin ◽  
Ilya Vlasov ◽  
Olegas Prentkovskis ◽  
Iryna Danyliuk
Keyword(s):  
Fatigue Crack ◽  
Residual Life ◽  
Degradation Kinetics ◽  
Life Time ◽  
Nucleation And Growth ◽  
Gas Pipelines ◽  
Deformation And Fracture ◽  
Structural Levels ◽  
Kinetics Of

The majority of modern gas pipelines in Ukraine, Lithuania and Russia have been operating for more than 30–40 years. The problem of forecasting residual life-time of materials comprising such gas pipelines calls for study of their degradation kinetics as well as requires to determine its relationship with the strain-force loading parameters. The aim of the paper is to study the kinetics of fracture in order to range mechanisms of cyclic deformation of 17Mn1Si steel at nucleation and growth of a fatigue crack. Flat specimens were cut out from a fragment of 17Mn1Si steel pipe after 40 years of service. Microstructures of specimens were examined. In the paper, an attempt was made to apply the combined approach to study of deformation and fracture based on the following research parameters from nonlinear fracture mechanics: physical mesomechanics and numerical fractography.

Kinetics of fatigue crack growth and crack closure effect in long term operating steel manufactured at the turn of the 19 th and 20 th centuries

2017 ◽  
Vol 185 ◽  
pp. 160-174 ◽  
Author(s):  
Grzegorz Lesiuk ◽  
Mieczysław Szata ◽  
José A.F.O. Correia ◽  
A.M.P. De Jesus ◽  
Filippo Berto
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Crack Closure ◽  
Closure Effect ◽  
Kinetics Of

scholarly journals Evaluation of Kinetic Pseudo-Order in the Photocatalytic Degradation of Ofloxacin

Catalysts ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 24
Author(s):  
Giora Rytwo ◽  
Arye Lev Zelkind
Keyword(s):  
Half Life ◽  
Advanced Oxidation Processes ◽  
Degradation Kinetics ◽  
Simple Procedure ◽  
Life Time ◽  
Zero Order Kinetics ◽  
Low Concentrations ◽  
Antibiotic Drug ◽  
Kinetics Of ◽  
Additional Reduction

Ofloxacin is a highly efficient and widely used antibiotic drug. It is classified as a refractory pollutant due to its poor biodegradability. Consequently, it is commonly found in water sources, requiring efficient methods for its removal. Advanced oxidation processes (AOPs) offer efficient alternatives since those yield complete degradation not achieved in adsorption or membrane processes. Previous studies suggest ofloxacin degradation follows a pseudo-first or -second order processes, whereas for full removal of refractory pollutants—lower pseudo-orders are required. Monitoring the actual “pseudo-order” degradation kinetics of ofloxacin is needed to evaluate any proposed AOP process. This study presents a simple procedure to evaluate pseudo-orders of AOPs. Photolysis of 20 μM ofloxacin solutions follow pseudo-zero order kinetics, with half-life times (t1/2) of approx. 60 min. TiO2 heterogenous catalysts have been shown to have no influence at low concentrations (0.2 mg L−1), but a significant reduction of half-life time (t1/2 = 20 min) and increase in pseudo-order (0.8) is measured at 2.0 mg L−1. Similar results are obtained with homogenous catalysis by 2.0 mg L−1 H2O2. The combination of H2O2 and TiO2 catalysts shows additional reduction in half-time life with increase in the pseudo-order to 1.2. The conclusions are (1) heterogenous and homogenous photocatalysis can effectively degrade ofloxacin, (2) combined photocatalysis yields higher pseudo-order, being less prone to achieve full removal, and (3) analysis of specific pseudo-orders in AOPs of refractory pollutants helps to further elucidate the efficiency of the processes.

Calculational-Experimental Monitoring of Radiation Damage Parameters on VVER Equipment and Their Application During Equipment Residual Life-Time Estimation

2018 ◽  
Author(s):  
Pavel Borodkin ◽  
Azamat Gazetdinov ◽  
Nikolay Khrennikov
Keyword(s):  
Service Life ◽  
Residual Life ◽  
Time Estimation ◽  
Life Time ◽  
Point Of View ◽  
Fast Neutrons ◽  
Fluence Rate ◽  
Radiation Load ◽  
Reactor Pressure

The problem of ensuring the integrity of VVER type reactor equipment integrity is now most significant in connection with justifying the safety of the NPP units and the extension of their service life-time to 60 years and more. This issue primarily first of all concerns long term operated NPP power units with VVER-440s and VVER-1000s. The justification of the VVER equipment integrity depends on the reliability of estimation of the degree of the equipment damage. One of the mandatory requirements [1], providing the reliability of such estimation, and also the evaluation of VVER equipment life-time, is the monitoring of equipment radiation loading parameters. Relative to this requirement there is a problem the challenge of justification of such the normative parameters, used for an estimating of the reactor pressure vessel (RPV) metal embrittlement, as the fluence and fluence rate of fast neutrons with energies above 0,5 MeV. Compliance with these requirements is analyzed during regular monitoring of radiation load parameters, which is performed by SEC NRS for all Russian NPP from the regulatory point of view. As a result of this activity, SEC NRS has recently elaborated one of the new approaches aimed to monitoring the radiation load of all equipment of Russian VVERs. The paper describes these approaches and shows the way of their implementation during monitoring procedures.

Evaluation of Kinetic Pseudo-Order in the Photocatalytic Degradation of Oflaxicin

2021 ◽  
Author(s):  
Giora Rytwo ◽  
Arye Lev Zelkind
Keyword(s):  
Half Life ◽  
Advanced Oxidation Processes ◽  
Degradation Kinetics ◽  
Simple Procedure ◽  
Life Time ◽  
Zero Order Kinetics ◽  
Antibiotic Drug ◽  
Heterogenous Catalyst ◽  
Kinetics Of ◽  
Additional Reduction

Ofloxacin is a highly efficient and widely used antibiotic drug. It is classified as a refractory pollutant due to its poor biodegradability. Consequently, it is commonly found in water sources, requiring efficient methods for its removal. Advanced Oxidation Processes (AOPs) offer efficient alternatives since those yield complete degradation not achieved in adsorption or membrane processes. Previous studies suggest ofloxacin degradation follows a pseudo-first or -second order processes, whereas for full removal of refractory pollutants – lower pseudo-orders are required. Monitoring the actual “pseudo-order” degradation kinetics of ofloxacin is needed to evaluate any proposed AOP process. This study presents a simple procedure to evaluate pseudo-orders of AOPs. Photolysis of 20 mM ofloxacin solutions follow pseudo-zero order kinetics, with half-life times (t1/2) of approx. 60 min. TiO2 heterogenous catalyst show to have no influence at low concentration (0.2 mg L-1) but a significant reduction of half-life time (t1/2 = 20 min) and increase in pseudo-order (0.8) is measured at 2.0 mg L-1. Similar results are obtained with homogenous catalysis by 2.0 mg L-1 H2O2. The combination of H2O2 and TiO2 catalysts shows additional reduction in half-time life with increase in the pseudo-order to 1.2. The conclusions are (1) heterogenous and homogenous photocatalysis can effectively degrade ofloxacin, (2) combined photocatalysis yields higher pseudo-order, being less prone to achieve full removal, (3) analysis of specific pseudo-orders in AOPs of refractory pollutants helps to further elucidate the efficiency of the processes.

Long term behaviour and degradation kinetics of tributyltin in a marina sediment

1995 ◽  
Vol 170 (1-2) ◽  
pp. 59-70 ◽  
Author(s):  
Pierre-Marie Sarradin ◽  
Yves Lapaquellerie ◽  
Annette Astruc ◽  
Claude Latouche ◽  
Michel Astruc
Keyword(s):  
Degradation Kinetics ◽  
Kinetics Of

scholarly journals Degradation kinetics of six sulfonamides in hen eggs under simulated cooking temperatures

2011 ◽  
Vol 76 (8) ◽  
pp. 1093-1101 ◽  
Author(s):  
Xin-Huai Zhao ◽  
Peng Wu ◽  
Ying-Hua Zhang
Keyword(s):  
Rate Constants ◽  
Half Life ◽  
Heating Temperature ◽  
Degradation Kinetics ◽  
Life Time ◽  
Hplc Method ◽  
First Order ◽  
Order Rate ◽  
Apparent Activation Energies ◽  
Kinetics Of

Six sulfonamides, i.e., sulfadiazine, sulfadimethoxine, sulfamerazine, sulfamethazine, sulfamethoxazole and sulfamonomethoxine, were applied to spike whole hen eggs at 0.1 mg kg- 1 eggs. The spiked hen eggs were heated at 80 and 100 ?C to investigate the degradation kinetics of the sulfonamides under simulated cooking conditions. The sulfonamides added were extracted twice from the spiked eggs with dichloromethane by an ultrasonic-assistant extraction, and analyzed by a HPLC method after purification. The first-order rate constants and half-life times of the sulfonamides were calculated, and the corresponding apparent activation energy of their degradation was also obtained by application of the Arrhenius equation. The results indicated that all six sulfonamides degraded faster at the higher heating temperature, with first-order rate constants ranging from 0.0056 to 0.0108 min-1 at 80 ?C and from 0.0147 to 0.0394 min-1 at 100 ?C. The apparent activation energies for the degradation of the sulfonamides were estimated to be in the range 30.9 to 77.5 kJ mol-1. Sulfadiazine and sulfadimethoxine had the shortest and longest half-life time, respectively, and were the most instable and stable.

scholarly journals Dimethoate degradation in plants and during processing of yerba maté leaves

2002 ◽  
Vol 45 (4) ◽  
pp. 419-422 ◽  
Author(s):  
Miguel E. Schmalko ◽  
Laura A. Ramallo ◽  
Darío Ferreira ◽  
Rubén D. Berlingheri
Keyword(s):  
Gas Chromatography ◽  
Half Life ◽  
Degradation Kinetics ◽  
Life Time ◽  
Ilex Paraguariensis ◽  
Yerba Mate ◽  
Initial Value ◽  
Mass Selective Detector ◽  
Selective Detector ◽  
Kinetics Of

The objective of this research was to study degradation kinetics of dimethoate in plants of Ilex paraguariensis Saint Hilaire (or yerba maté) and during its processing. To determine dimethoate concentration, a capillary gas chromatography technique with a mass selective detector was used. Half-life times in plants ranked between 9.8 and 11.8 days. During processing, with a blanching and two drying steps, dimethoate concentration decayed to a 22.7% of its initial value (in dry basis); while during seasoning step (at 45°C), half-life time was 17.3 days. With these values, preharvest safety interval was determined.

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