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    Tytuł:
    Parametric Optimization for Producing Semi-Solid A383 Alloy using Cooling Slope Casting Process
    Autorzy:
    Rao, M. S.
    Khandelwal, Himandshu
    Kumar, M.
    Kumar, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/27314114.pdf
    Data publikacji:
    2023
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    alloy A383
    semi-solid alloys
    casting process
    cooling
    hardness
    non-dendritic microstructur
    stop A383
    stopy półstałe
    proces odlewania
    chłodzenie
    twardość
    mikrostruktura
    Opis:
    Cooling slope casting is a simple technique to produce semi-solid feedstock with a non-dendritic structure. The cooling slope technique depends on various parameters like slope length, slope angle, pouring temperature etc, that has been investigated in the present study. This work presents an extensive study to comprehend the combined effect of slope angle, slope length, pouring temperature, on hardness and microstructure of A383 alloy. Response Surface Methodology was adopted for design of experiments with varying process parameters i.e. slope angle between 15o to 60o, slope length between 400 to 700 mm, and pouring temperature between 560 oC to 600 oC. The response factor hardness was analysed using ANOVA to understand the effect of input parameters and their interactions. The hardness was found to be increasing with increased slope length and pouring temperature; and decreased with slope angle. The empirical relation for response with parameters were established using the regression analysis and are incorporated in an optimization model. The optimum hardness with non-dendritic structure of A383 alloy was obtained at 27o slope angle, 596.5 mm slope length and 596 oC pouring temperature. The results were successfully verified by confirmation experiment, which shows around 2% deviation from the predicted hardness (87.11 BHN).
    Źródło:
    Archives of Foundry Engineering; 2023, 23, 1; 43--52
    1897-3310
    2299-2944
    Pojawia się w:
    Archives of Foundry Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Inventory models with multiple production and remanufacturing batches under shortages
    Autorzy:
    Singh, S. R.
    Sharma, S.
    Kumar, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/206729.pdf
    Data publikacji:
    2016
    Wydawca:
    Polska Akademia Nauk. Instytut Badań Systemowych PAN
    Tematy:
    inventory models
    production
    remanufacturing
    shortages
    Opis:
    Owing to the ecological requirements and regulations, an enormous concern is being paid to the product re-processing. In the established literature, researchers considered that the remanufactured items are as good as the new ones. Yet, such an assumption is not convenient, as in many real situations the recycled products are considered by the customers to be of secondary quality. Further, the classical studies mainly addressed the inventory models without shortages, and this is not applicable in many practical business situations. This paper extends the reverse logistics inventory models with finite production and remanufacturing rate along with the assumption that newly produced and repaired (remanufactured) objects are not of same characteristics. Shortages are allowed and numerous stock-out cases are discussed. The collected used items are remanufactured (repaired) and non-repaired products are disposed off. The proposed models are illustrated with some numerical examples and their results are discussed.
    Źródło:
    Control and Cybernetics; 2016, 45, 3; 385-416
    0324-8569
    Pojawia się w:
    Control and Cybernetics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Kernel function based regression approaches for estimating the oxygen transfer performance of plunging hollow jet aerator
    Autorzy:
    Kumar, M.
    Tiwari, N. K.
    Ranjan, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/368684.pdf
    Data publikacji:
    2019
    Wydawca:
    Stowarzyszenie Komputerowej Nauki o Materiałach i Inżynierii Powierzchni w Gliwicach
    Tematy:
    volumetric oxygen transfer coefficient
    multiple nonlinear regression
    Gaussian process regression
    support vector regression
    współczynnik wnikania tlenu
    regresja nieliniowa
    proces gaussowski
    regresja wektora wsparcia
    Opis:
    Purpose: To evaluate the capability of various kernels employed with support vector regression (SVR) and Gaussian process regression (GPR) techniques in estimating the volumetric oxygen transfer coefficient of plunging hollow jets. Design/methodology/approach: In this study, a data set of 81 observations is acquired from laboratory experiments of hollow jets plunging on the surface of water in the tank. The jet variables: jet velocity, jet thickness, jet length, and water depth are varied accordingly and the values of volumetric oxygen transfer coefficient is computed. An empirical relationship expressing the oxygenation performance of plunging hollow jet aerator in terms of jet variables is formulated using multiple nonlinear regression. The performance of this nonlinear relationship is compared with various kernel function based SVR and GPR models. Models developed with the training data set (51 observations) are checked on testing data set (24 observations) for performance comparison. Sensitivity analysis is carried out to examine the influence of jet variables in effecting the oxygen transfer capabilities of plunging hollow jet aerator. Findings: The overall comparison of kernels yielded good estimation performance of Radial Basis Function kernel (RBF) and Pearson VII Function kernel (PUK) using the SVR technique which is followed by nonlinear regression, and other kernel function based regression models. Research limitations/implications: The results of the study pertaining to the performance of kernels are based on the current experimental conditions and the estimation potential of the regression models may fluctuate beyond the selection of current data range due to datadependant learning of the soft computing models. Practical implications: Volumetric oxygen transfer coefficient of plunging hollow jets can be predicted precisely using SVR model by employing RBF as kernel function as compared to empirical correlation and other kernel function based regression models. Originality/value: The comparative analysis of kernel functions is conducted in this study. In previous studies, the predictive modelling approaches are implemented in simulating the aeration properties of cylindrical solid jets only, while this paper simulates the volumetric oxygen transfer coefficient of diverging hollow jets with the jet variables by utilizing polynomial, normalized polynomial, PUK, and RBF kernels in SVR and GPR.
    Źródło:
    Journal of Achievements in Materials and Manufacturing Engineering; 2019, 95, 2; 74-84
    1734-8412
    Pojawia się w:
    Journal of Achievements in Materials and Manufacturing Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Assessment of dental professionals’ maintenance of management practices developed and incorporated during COVID-19 pandemic – a cross-sectional study
    Autorzy:
    Singh, R.
    Sekhon, T.
    Sekhon, S.
    Kumar, M.
    Nirola, A.
    Gambhir, R.S.
    Powiązania:
    https://bibliotekanauki.pl/articles/28765158.pdf
    Data publikacji:
    2023
    Wydawca:
    Narodowy Instytut Zdrowia Publicznego. Państwowy Zakład Higieny
    Opis:
    Background. COVID-19 pandemic has been a source of emerging public health problems for the past few years. Due to its contagious nature, health care professionals especially dentists, incorporated various modifications in their practices to prevent themselves and their patients from the risk of getting infected. Objective. The present study aims to assess whether dental professionals are still continuing with those modifications in practice in current times. Materials and Methods. The present study was conducted on 415 subjects after getting due approval from concerned authorities and consent from the subjects. Systematic random sampling methodology was employed for selection for study sample. The study employed a self-constructed questionnaire which was divided into 2 parts and information regarding demographic profile, practice modifications and safety protocols was gathered from subjects. Statistical analysis was conducted using Chi-square test and multiple regression analysis. Results. Only 8.6% of subjects were currently continuing with their all previous practice modifications. A vast majority of subjects (83.8%) were not deferring treatment of patients showing suspicious symptoms. Approximately 89% of subjects were not sanitizing the operating area at the end of the working day. More than two-thirds (76.4%) of the subjects stated that the pandemic was over. Female gender (OR:1.67) and high level of education (OR:2.45) had an important effect on the continuation of practice modifications. Conclusion. Very few subjects were adhering to all practice modifications previously incorporated. Dental professionals should not let their guard down even if COVID-19 cases have reduced considerably. The information collected will be useful for the dental community and further studies should be carried out.
    Źródło:
    Roczniki Państwowego Zakładu Higieny; 2023, 74, 3; 309-314
    0035-7715
    Pojawia się w:
    Roczniki Państwowego Zakładu Higieny
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Biosorption of aniline blue from aqueous solution using a novel biosorbent Zizyphus oenoplia seeds: Modeling studies
    Autorzy:
    Kumar, M.
    Elangovan, G
    Tamilarasan, R
    Vijayakumar, G.
    Mukeshkumar, P. C.
    Sendhilnathan, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/778750.pdf
    Data publikacji:
    2015
    Wydawca:
    Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
    Tematy:
    aniline blue
    removal
    biosorption
    Zizyphus oenoplia seed
    modeling
    Opis:
    This article presents the feasibility for the removal of Aniline Blue dye (AB dye) from aqueous solution using a low cost biosorbent material Zizyphus oenoplia seeds. In this study, a batch mode experiments of the adsorption process were carried out as a function of pH, contact time, concentration of dye, adsorbent dosage and temperature. The experimental data were fitted with Freundlich and Langmuir isotherm equations. The feasibility of the isotherm was evaluated with dimensionless separation factor (RL). The kinetic data of sorption process are evaluated by using pseudo-first order and pseudo-second order equations. The mode of diffusion process was evaluated with intra-particle diffusion model. The thermodynamic parameters like change in enthalpy (ΔHº); change in entropy (ΔSº) and Gibbs free energy change (ΔGº) were calculated using Van’t Hoff plot. The biosorbent material was characterized with Fourier Transform Infrared (FTIR) spectroscopy and the morphology was identified with Scanning Electron Microscope (SEM) in before and after adsorption of AB dye.
    Źródło:
    Polish Journal of Chemical Technology; 2015, 17, 3; 70-77
    1509-8117
    1899-4741
    Pojawia się w:
    Polish Journal of Chemical Technology
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-5 z 5

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