Aloke Dey

Fractional factorial plans

Fractional Plans and Orthogonal Arrays. Symmetric Orthogonal Arrays. Asymmetric Orthogonal Arrays. Some Results on Nonexistence. More on Optimal Fractional Plans and Related Topics. Trend-Free Plans and Blocking. Some Further Developments. Appendix. References. Index.

Optimal designs for diallel cross experiments

Using nested balanced incomplete block designs, new families of optimal block designs for a certain type of dialled cross experiments are obtained. It is further shown that triangular partially balanced incomplete block designs satisfying a certain parametric condition also lead to optimal designs for diallel crosses. These results unify and extend some of the earlier results on optimality of block designs for diallel crosses.

D-optimal designs for covariate models

The problem of finding D-optimal or D-efficient designs in the presence of covariates is considered under a completely randomized design set-up with v treatments, k covariates and N experimental units. In contrast to Lopes Troya [Lopes Troya, J., 1982, Optimal designs for covariates models. Journal of Statistical Planning and Inference, 6, 373–419.], who considered this problem in the equireplicate case, we do not assume that N/v is an integer, and this allows us to study situations where no equireplicate design exists. Even when N/v is an integer, it is seen quite counter-intuitively that there are situations where a non-equireplicate design outperforms the best equireplicate design under the D-criterion.

Universal optimality of block designs with unequal block sizes

The universal optimality of some block designs with unequal block sizes is studied, under the usual homoscedastic model and under a certain heteroscedastic model.

Key predistribution schemes for distributed sensor networks via block designs

Key predistribution schemes for distributed sensor networks have received significant attention in the recent literature. In this paper we propose a new construction method for these schemes based on combinations of duals of standard block designs. Our method is a broad spectrum one which works for any intersection threshold. By varying the initial designs, we can generate various schemes and this makes the method quite flexible. We also obtain explicit algebraic expressions for the metrics for local connectivity and resiliency. These schemes are quite efficient with regard to connectivity and resiliency and at the same time they allow a straightforward shared-key discovery.

Robustness of some designs against missing observations

This paper investigates the robustness of certain designs against the loss of specified sets of observations. As a measure of robustness, we consider the efficiency of the residual design.

Experimental results and analysis for Electrical Discharge Machining (EDM) of aluminium metal matrix composites with powder-mixed dielectric: Lenth's method

This paper reports the work on EDM with SiC abrasive powder-mixed dielectric, a hybrid process. The machining of 6061Al/Al2O3p/20p work specimens has been carried out with copper electrode. An L18 orthogonal array (OA) was employed for the optimisation of the performance measures such as material removal rate and surface roughness. The effects of seven control factors (three levels each) and a noise factor (two level), and one two-variable interactions on the responses were quantitatively evaluated by the Lenths method. Analysed results indicate that the process effectively improves the MRR and reduces the surface roughness, in comparison with the conventional EDM.

Construction of asymmetric orthogonal arrays through finite geometries

Finite geometries are used to construct several families of asymmetric orthogonal arrays. Many of these arrays appear to be new.

Robustness of some designs against missing data

This article studies the robustness of several types of designs against missing data. The robustness of orthogonal resolution III fractional factorial designs and second-order rotatable designs is studied when a single observation is missing. We also study the robustness of balanced incomplete block designs when a block is missing and of Youden square designs when a column is missing.

Construction of nested orthogonal arrays

A (symmetric) nested orthogonal array is a symmetric orthogonal array OA(N,k,s,g) which contains an OA(M,k,r,g) as a subarray, where M