optimization methods can be applied to existing products to identify potential
design improvements.
Thermal system design includes an optimization process in which the designer
considers certain objectives such as heat transfer rate, thermal resistance, total cost,
friction factor, pressure amplitude, effectiveness, cooling capacity, pressure drop,
etc. depending on the requirements. Whil e achieving the mentioned objectives, it is
also desirable to minimize the total cost of the system. However, the design opti-
mization for a whole thermal syste m assembly may be having a complex objective
function with a large number of design variables. So, it is a good practice to apply
optimization techniques for individual component or intermediate system than to a
whole system. For example, in a thermal power plant, individual optimization of
cooling tower, heat pipe and heat sink is computationally and mathematically
simpler than the optimization of whole power plant.
In the case of manufacturing of products, in order to survive in a competitive
market scenario, industries are required to manufacture products with highest
quality at a lowest possible cost, fulfill the fast-changing customer desires, consider
significance of aesthetics and conform to environmental norms, adopt flexibili ty in
the production system and minimize time-to market of their products. Industries
employ a numbe r of manufacturing processes to transform raw materials into fin-
ishing goods and efficient utilization of these manufacturing processes is important
to achieve the above goals. Manufacturing processes are characterized by a number
of input parameters which signi ficantly influence their performances. Therefore,
determining best combination of the input parameters is an important task for the
success of any manufacturing process.
A human process planner may select proper combination of process parameters
for a manufacturing process using his own experience or machine catalog. The
selected parameters are usually conservative and far from optimum. Selecting a
proper combination of process parameters through experimentation is costly, time
consuming and requires a number of experimental trials. Therefore researchers have
opted to use optimization techniques for process parameter optimization of man-
ufacturing processes. Researchers have used a number of traditional optimization
techniques like geometric programming, nonlinear programming, sequential pro-
gramming, goal programming, dynamic programming, etc. for process parameter
optimization of manufacturing processes. Although the traditional optimization
methods had performed well in many practical cases, but they have certain limi-
tations which are mainly related to their inherent search mechanisms. Search
strategies of these traditional optimization methods are generally depended on the
type of objective and constraint functions (linear, non-linear, etc.) and the type of
variables used in the problem modeling (integer, binary, continuous, etc.), their
efficiency is also very much dependent on the size of the solution space, number of
variables and constraints used in the problem modeling and the structure of the
solution space (convex, non-convex, etc.), the solutions obtained largely depends
upon the selected initial solution. They also do not provide generic solution
approaches that can be used to solve problems where different types of variables,
objective and constraint functions are used. In real world optimization problems the
2 1 Introduction