The problem of optimizing the reliability of complex systems has been modeled as a fuzzy multi-objective optimization problem. Three different kinds of optimization problems: reliability optimization of a complex system with constraints on cost and weight; optimal redundancy allocation in a multistage mixed system with constraints on cost and weight; and optimal reliability allocation in a multistage mixed system with constraints on cost, weight, and volume have been solved. Four numerical examples have been solved to demonstrate the effectiveness of the present methodology. The influence of various kinds of aggregators is also studied. The inefficiency of the noncompensatory min operator has been demonstrated. One of the well-known global optimization meta-heuristics, the threshold accepting, has been invoked to take care of the optimization part of the model. A software has been developed to implement the above model. The results obtained are encouraging.

In a developing country like India, classification and identification of the species of Anopheline mosquitoes in control operations of mosquito-borne diseases is of paramount importance. The WHO monograph, which describes the taxonomic data in the form of a pictorial key is generally difficult to understand by a non-taxonomist. Utilizing the principles of ID3 algorithm, a novel rule-based system, for the fast identification of unknown species of Indian Anopheline mosquitoes, is developed. The rule-based system is user-friendly, menu-driven and even a novice can make use of it in the identification of the unknown species with little practice. The above software is available on floppy disk and can be obtained with a minimum cost. This program can be ported on 5 1/4" or 3 1/2" floppy disk.

The probit analysis model is generally used for the determination of lethal dosages in bioassay applications. However, the logit models, which use the logistic curve instead of the integrated normal curve, could also be effectively used for the determination of lethal dosages and regression coefficients. In this paper, two types of logit models, namely minimum logit chi square and maximum likelihood, have been described in detail for the estimation of the parameters. The results of these two models are also compared with those of the probit model.

Probit analysis calculations are highly useful in biology and related sciences. Since the statistical calculations and tests required are quite involved, the use of an automatic computer program is desirable. The description of the computational procedures and use of the computer program with suitable examples from mosquito control programmes are discussed.