General Optimization Procedure Research Articles

Optimization Methods Applied to the Aerodynamic Design of Helicopter Rotor Blades

This paper describes a formal optimization procedure for helicopter rotor blade designs which minimizes hover horsepower while assuring satisfactory forward flight performance. The approach is to couple hover and forward flight analysis programs with a general purpose optimization procedure. The resulting optimization system provides a systematic evaluation of the rotor blade design variables and their interaction, thus reducing the time and cost of designing advanced rotor blades. The paper discusses the basis for and details of the overall procedure, describes the generation of advanced blade designs for representative Army helicopters, and compares designs and design effort with those from the conventional approach which is based on parametric studies and extensive cross-plots.

The Use of Optimization Techniques to Design-Controlled Diffusion Compressor Blading

A method is presented for automating compressor blade design using numerical optimization and is applied to the design of a controlled diffusion stator blade row. A general purpose optimization procedure is employed, which is based on conjugate directions for locally unconstrained problems and on feasible directions for locally constrained problems. Coupled to the optimizer is an analysis package consisting of three analysis programs which calculate blade geometry, inviscid flow, and blade surface boundary layers. The optimization concepts are briefly discussed. Selection of design of a two-dimensional blade section is discussed, and design results are presented.

Identification and interpretation of spectra by logical comparison of spectral information sets: Part 2. Optimization of library search methods

Summary The success of library search methods depends on the composition of the spectra library. The parameters of library search methods must therefore be optimized with respect to the spectra library used. A general optimization procedure based on information theory is given.

Job Scheduling in a Single-Node Hierarchical Network for Process Control

The operating characteristics of a typical single-node hierarchical element in a multiprocessor network such as might be used for process control are described, and the class of scheduling problems arising from the use of such a network is discussed and related to similar problems which have been reported in the literature. Two measures of system performance are then defined: the settling time, defined as the maximum of the finishing times of all jobs when a set of jobs is initiated once in the network, and the steady-state service, a related performance index for the case where jobs are initiated on a periodic basis. Finally, a simulation model is used to evaluate the operating characteristics of the hierarchical network using the two metrics in conjunction with several synthetic workloads; a general optimization procedure is shown to lead to values of scheduling parameters which are close to optimal even for network workloads with many degrees of freedom (i.e., when many computers are initiating jobs).

A Lumped Parameter Approach to Vibration and Stress Analysis of Elastic Linkages

A method of kineto-elastodynamic analysis is developed employing lumped parameter models for simulating moving mechanism components considered as simply-supported beams subject to in-plane bending. Application of finite difference approximations to Euler’s beam theory leads to a system of nonlinear, ordinary differential equations of motion, and numerical solution of these equations is illustrated for specific examples. Variable as well as uniform cross-section members are analyzed for elastic vibration and stresses. By means of a general optimization procedure presented, nonuniform beam contours are obtained which provide a substantial stress reduction relative to the uniform case, without a corresponding increase in total mass.

Chemical thermodynamics for optimization of epitaxial film deposition processes

Systems used in epitaxial technology are classified from the point of view of the amount of initial information needed and the appropriate method of thermodynamic analysis to be used. New technological possibilities are revealed by application of the analysis to some typical systems with several depositing elements. The role of thermodynamic analysis in general optimization procedure is outlined.