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    Wyświetlanie 1-5 z 5
    Tytuł:
    Composite Barrier to Control the Corrosion of Mild Steel in Oil Well
    Autorzy:
    Singh, Rajesh Kumar
    Thakur, Manjay Kumar
    Kumar, Parshun
    Powiązania:
    https://bibliotekanauki.pl/articles/1030680.pdf
    Data publikacji:
    2020
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    HCl
    Mild steel
    Saline water
    composite barrier
    filler
    thermal parameters
    Opis:
    Mild steel is a very important engineering metal. Petrochemical industries are used bulk amount for their various purposes like recovery of crude oil, refinery units and transportation. Crude oil is a very highly viscous liquid for the opening of the month well strong HCl acid and saline water is used. They produce hostile environment of mild steel. Gaseous substances like CO2 and SO2 gases are found into the well of petroleum. Large amount of saline water are used during recovery of crude oil in this water CO2 and SO2 are dissolved to produce H2CO3 and H2SO4. These acids create an acidic medium of mild steel. Saline waters have possessed Cl¯ ions. It produces ambient environment for mild steel. The solution of salty water contains dissolve oxygen which develop corrosive environment of mild steel. These major corrosive substances are available during recovery of crude oil and they form corrosion cell with base metal. Metal produces galvanic, pitting, stress, crevice, intergranular corrosion. Nanocaoting and filler methods are used to protect metal in such un-friendly environment. The corrosion rate of metal was calculated by weight loss experiment in absence and presence of nanocoating and filler materials. The synthesized organic compound octahydrodibenzo[a,d][8]annulene-5,12-dihydrazone is applied for nanocoating and MgS as filler. The coating and filling works were completed by chemical vapour deposition and nozzle spray method. Potentiostat used for determination corrosion potential and corrosion current density. The surface adsorption was studied by thermal parameters like activation energy, heat of adsorption, free energy, enthalpy and entropy. The thermal parameters results were shown that coating and filler compounds were adhered with base metal by chemical bonding. The thermal results were calculated by Arrhenius equation and Langmuir isotherm. The coating and the filler substance formed composite barrier with metal and developed a protective barrier for the corrosive substances.
    Źródło:
    World Scientific News; 2020, 139, 2; 155-172
    2392-2192
    Pojawia się w:
    World Scientific News
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Degrading systems availability analysis: analytical semi-Markov approach
    Autorzy:
    Kumar, Varun
    Kumar, Girish
    Singh, Rajesh Kumar
    Soni, Umang
    Powiązania:
    https://bibliotekanauki.pl/articles/1841831.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Polskie Naukowo-Techniczne Towarzystwo Eksploatacyjne PAN
    Tematy:
    availability
    perfect repair
    opportunistic maintenance
    Embedded Markov Chain (EMC)
    Cumulative Density Function (CDF)
    Semi-Markov Process (SMP)
    Opis:
    This paper deals with modeling and analysis of complex mechanical systems that deteriorate with age. As systems age, the questions on their availability and reliability start to surface. The system is believed to suffer from internal stochastic degradation mechanism that is described as a gradual and continuous process of performance deterioration. Therefore, it becomes difficult for maintenance engineer to model such system. Semi-Markov approach is proposed to analyze the degradation of complex mechanical systems. It involves constructing states corresponding to the system functionality status and constructing kernel matrix between the states. The construction of the transition matrix takes the failure rate and repair rate into account. Once the steady-state probability of the embedded Markov chain is computed, one can compute the steady-state solution and finally, the system availability. System models based on perfect repair without opportunistic and with opportunistic maintenance have been developed and the benefits of opportunistic maintenance are quantified in terms of increased system availability. The proposed methodology is demonstrated for a two-stage reciprocating air compressor with intercooler in between, system in series configuration.
    Źródło:
    Eksploatacja i Niezawodność; 2021, 23, 1; 195-208
    1507-2711
    Pojawia się w:
    Eksploatacja i Niezawodność
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Degrading systems availability analysis: analytical semi-Markov approach
    Autorzy:
    Kumar, Varun
    Kumar, Girish
    Singh, Rajesh Kumar
    Soni, Umang
    Powiązania:
    https://bibliotekanauki.pl/articles/1841749.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Polskie Naukowo-Techniczne Towarzystwo Eksploatacyjne PAN
    Tematy:
    availability
    perfect repair
    opportunistic maintenance
    embedded Markov chain
    EMC
    cumulative density function
    CDF
    semi-Markov process
    SMP
    Opis:
    This paper deals with modeling and analysis of complex mechanical systems that deteriorate with age. As systems age, the questions on their availability and reliability start to surface. The system is believed to suffer from internal stochastic degradation mechanism that is described as a gradual and continuous process of performance deterioration. Therefore, it becomes difficult for maintenance engineer to model such system. Semi-Markov approach is proposed to analyze the degradation of complex mechanical systems. It involves constructing states corresponding to the system functionality status and constructing kernel matrix between the states. The construction of the transition matrix takes the failure rate and repair rate into account. Once the steady-state probability of the embedded Markov chain is computed, one can compute the steady-state solution and finally, the system availability. System models based on perfect repair without opportunistic and with opportunistic maintenance have been developed and the benefits of opportunistic maintenance are quantified in terms of increased system availability. The proposed methodology is demonstrated for a two-stage reciprocating air compressor with intercooler in between, system in series configuration.
    Źródło:
    Eksploatacja i Niezawodność; 2021, 23, 1; 195-208
    1507-2711
    Pojawia się w:
    Eksploatacja i Niezawodność
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Optimization of T-6 cycle and Characterization of Si3N4 Reinforced High Strength Aluminum Metal Matrix Composites
    Autorzy:
    Kumar, Ashish
    Rana, Ravindra Singh
    Purohit, Rajesh
    Namdev, Anurag
    Powiązania:
    https://bibliotekanauki.pl/articles/28099516.pdf
    Data publikacji:
    2023
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    stir casting
    microstructure
    mechanical properties
    optimization
    fractography
    Opis:
    In this research, AA7068/Si3N4 composites were fabricated through stir casting with the attachment of ultrasonic treatment. The quenching medium and aging duration significantly influenced the hardness of Al alloy samples. Peak hardness was achieved after 12 h of artificial aging at the temperature of 140°C. The addition of nano Si3N4 significantly refined the microstructure of unreinforced AA7068. The dispersion of intermetallic compounds (MgZn2) and grain boundary discontinuation were noticed after the T-6 heat treatment. Ultimate tensile strength, yield strength, and hardness were improved by 70.95%, 76.19%, and 44.33%, respectively, with the addition of 1.5 weight % Si3N4 compared to as-cast alloy due to the combined effect of heat treatment, hall-Petch, Orowan, thermal miss match, load-bearing strengthening mechanisms and uniform dispersion of reinforcement. A reduction in percentage elongation was noticed due to composites’ brittle nature by the effect of ceramic Si3N4 particles’ inclusion. The fracture surfaces reveal ductile failure for alloy and mixed-mode failure in the case of composites.
    Źródło:
    Archives of Metallurgy and Materials; 2023, 68, 2; 775--783
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A General Family of Dual to Ratio-Cum-Product Estimator in Sample Surveys
    Autorzy:
    Singh, Rajesh
    Kumar, Mukesh
    Chauhan, Pankaj
    Sawan, Nirmala
    Smarandache, Florentin
    Powiązania:
    https://bibliotekanauki.pl/articles/465772.pdf
    Data publikacji:
    2011
    Wydawca:
    Główny Urząd Statystyczny
    Tematy:
    Family of estimators
    auxiliary variables
    bias
    mean-squared error
    Opis:
    This paper presents a family of dual to ratio-cum-product estimators for the finite population mean. Under simple random sampling without replacement (SRSWOR) scheme, expressions of the bias and mean-squared error (MSE) up to the first order of approximation are derived. We show that the proposed family is more efficient than usual unbiased estimator, ratio estimator, product estimator, Singh estimator (1967), Srivenkataramana (1980) and Bandyopadhyaya estimator (1980) and Singh et al. (2005) estimator. An empirical study is carried out to illustrate the performance of the constructed estimator over others.
    Źródło:
    Statistics in Transition new series; 2011, 12, 3; 587-594
    1234-7655
    Pojawia się w:
    Statistics in Transition new series
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-5 z 5

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