Effects of low vehicle speed on the service life time of asphalt pavements

2015 ◽  
pp. 221-226 ◽  
Author(s):  
A Walther ◽  
I Isailović
Keyword(s):  
Service Life ◽  
Life Time ◽  
Asphalt Pavements ◽  
Vehicle Speed

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.

Study of drilling muds on the anti-erosion property of a fluidic amplifier in directional drilling

2015 ◽  
Author(s):  
Jiang-fu He ◽  
Peng-yu Zhang ◽  
Qi-lei Yin ◽  
Kun Yin ◽  
Hou-ping Liu
Keyword(s):  
Particle Size ◽  
Service Life ◽  
High Speed ◽  
Great Influence ◽  
Life Time ◽  
Solid Content ◽  
Drilling Process ◽  
Jet Velocity ◽  
Drilling Muds ◽  
Erosion Property

Due to some drawbacks of conventional drilling methods and drilling tools, the application of hydraulic hammers with a fluidic amplifier have been extensively popularized since its emergence in recent years. However, the performance life of a fluidic amplifier is still unsatisfactory in oil and gas wells drilling, especially the heavy wear or erosion of the fluidic amplifier leads to the reduction of service life time of hydraulic hammers, which is derived from the incision of drilling muds with high speed and pressure. In order to investigate the influence of drilling muds, such as particle size, solid content and jet velocity, on the antierosion property of a fluidic amplifier, several groups of drilling muds with different performance parameters have been utilized to numerical simulation on basis of Computational Fluid Dynamics (CFD). Simulation results have shown that the jet nozzle of fluidic amplifiers is primarily abraded, afterwards are the lateral plates and the wedge of the fluidic amplifier, which shows extraordinary agreement with the actual cases of fluidic amplifier in drilling process. It can be concluded that particle size, solid content and jet velocity have a great influence on the anti-erosion property of a fluidic amplifier, and the erosion rate linearly varies with the particle size of drilling muds, nevertheless exponentially varies with solid content and jet velocity of drilling muds. As to improve the service life time of a fluidic amplifier, the mud purification system or low solid clay-free mud system is suggested in the operation of directional well drilling.

Influence of Boundary and Initial Condition on Durability of Concrete Structures Exposed to Chloride Environment

2012 ◽  
Vol 166-169 ◽  
pp. 1946-1953
Author(s):  
Xin Gang Zhou ◽  
Fang Zhao
Keyword(s):  
Service Life ◽  
Initial Conditions ◽  
Error Function ◽  
Concrete Structures ◽  
Life Time ◽  
Chloride Penetration ◽  
Analytical Models ◽  
Chloride Ingress ◽  
Chloride Environment ◽  
Penetration Profile

According to investigations of apparent surface chloride contents and chloride penetration profile of concrete structures exposed to chloride environment, the influences of boundary and initial conditions, geometry parameters such as the geometry dimension and section shape, etc. were discussed. Based on the Fick’s second law of diffusion and different boundary and initial conditions, different analytical models to predict the chloride penetration profile in concrete structural members with different boundary and initial conditions were derived. Some calculations examples were made using those analytical models. Computational results show that the boundary and initial conditions have remarkable influences on chloride penetration profile and service life time of concrete structures. Using prevailing error-function solution model based on the semi-infinite assumption of chloride ingress, the prediction of service life time of concrete structures are over evaluated, in particular for the steel reinforcement in corner of the section. Some modify coefficients should be taken into consideration, concerning the influences of boundary and initial conditions.

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