Research Article
Developing Robust Exponential Ratio and Product Estimators for Post-Stratification: Addressing Non-Response and Enhancing Accuracy Through Double Sampling
Issue:
Volume 12, Issue 1, March 2025
Pages:
1-10
Received:
4 January 2025
Accepted:
20 January 2025
Published:
7 February 2025
Abstract: A key survey sampling technique, post stratification, involves dividing a population that is diverse into strata with rather homogeneous members in order to improve population estimates. Modern large scale surveys often suffer from non-response, and these too will yield biased results. According to this paper, a new estimator which combines non response adjustment and double sampling techniques to improve the accuracy of product type and exponential ratio estimators is introduced. The proposed estimator has lower bias and mean squared error (MSE) on population mean estimators when response rates are incomplete. Theoretical derivations and empirical analysis on two real-world datasets—one on classroom activities and the other on agricultural yields—are shown to validate the estimator's performance. The Non Response Double Sampling (NRDS) estimator turns out to be much more efficient than traditional post stratification, separate ratio, and product type exponential estimators. These results indicate that the NRDS estimator is a robust and reliable way to handle missing within units within strata in stratified surveys, and that this estimator is a better way to improve the population mean estimates under conditions of non response.
Abstract: A key survey sampling technique, post stratification, involves dividing a population that is diverse into strata with rather homogeneous members in order to improve population estimates. Modern large scale surveys often suffer from non-response, and these too will yield biased results. According to this paper, a new estimator which combines non res...
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Research Article
Mathematical Modeling of Batch Fluidized Bed Drying of Alumina
Touil Amira*
,
Gritli Souhir,
Taieb Ahmed
Issue:
Volume 12, Issue 1, March 2025
Pages:
11-21
Received:
24 January 2025
Accepted:
7 February 2025
Published:
21 February 2025
Abstract: Fluidized bed drying is an efficient and widely used method for drying wet powders and granular products. To optimize this drying process, several approaches for modeling, including empirical, semi-empirical, or more complex computational fluid dynamics models are used. This work aims to simulate batch fluidized bed drying processes of alumina using the multi-phase model equation. Firstly, a thermodynamic characterization of alumina was carried out using the static gravimetric method to determine sorption isotherms, enthalpy and entropy. Than, drying kinetics at different operating conditions (temperature and air flow) are investigated. Finaly, A three-phase mathematical model describing the fluidized bed dryer has been provided based on a numerical method. The system of equations (heat and mass transfer) is solved numerically by the finite element method using "COMSOL multiphasic" software. Results show that, for the sorption isothermes, the increase in temperature inducing the decrease in the equilibrium water content, and that the GAB model can describe correctly experimental isotherms. The high sorption enthalpy value (8000 kJ/mol) is an indication of the strong water-solid surface interaction in the product. The desorption entropy has a high dependence on the water content, particularly for low water contents. The maximum desorption entropy value reaches 200 kJ/mol. K at low equilibrium water contents values. Temperature is the major factor influencing drying kinetics. According to the fluidized bed drying simulation, results show the capacity of the three-phase Kunii-Levenspiel model to describe and predect the spacio-temporal distribution of water content of alumina and temperature in the fluized bed during drying The model was validated on distinct operating conditions.
Abstract: Fluidized bed drying is an efficient and widely used method for drying wet powders and granular products. To optimize this drying process, several approaches for modeling, including empirical, semi-empirical, or more complex computational fluid dynamics models are used. This work aims to simulate batch fluidized bed drying processes of alumina usin...
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