Browsing by Subject "System Analysis."

Now showing 1 - 3 of 3

Open Access
Design and analysis of just-in-time production systems
(1988) Oğuz, Ceyda
Just-in-Time (JIT) production systems have initially appeared in the Japanese manufacturing environment due to the scarcity of their critical resources. The main aim in JIT production systems is to eliminate waste. To achieve this objective, setup times, lead times, in-process inventories, and defective production must all be minimized. In the design process of a JIT production system, several factors such as lot size, number of kanbans, unit load size, and buffer capacities must be taken into account. In this study, a mathematical model is developed for a single-item, single-line, multi-stage, and multi-period JIT production system. The original model is nonlinear in both objective function and constraints. To reduce the computational difficulties, the nonlinear model is then approximated by a linear model. Next, a simulation model is developed to incorporate the stochastic nature of the demand. A sensitivity analysis is performed on unit load size and on buffer capacity under different demand patterns to examine their effects on the behavior of the model. The results show that thofee unit load size values exceeding 10 percent of the maximum demand in the planning horizon have no effect on the model.
Open Access
Stability robustness analysis of linear systems
(1990) Karan, Mehmet
In this thesis, robustness of stability of linear, time-invariant, continuousand discrete-time systems is investigated. Only state-space models and additive perturbations are considered. Existing results concerning stability robustness of continuous-time systems, based on Liapunov approach and continuity of eigenvalues, are reviewed; and similar results for discretetime systems under single- and multi-parameter additive jDerturbations are derived. An inherent difficulty which originates from mixed linear and bilinear appearance of perturbation parameters in inequalities defining robustness regions of discrete-time systems is resolved by transforming the problem to robustness of a higher order continuous-time system. Finally, stability robustness of discrete-time interconnected systems is studied, and various approaches are compared.
Open Access
Stabilization of multivariable systems with constrained control structure
(1988) Ünyelioğlu, Konur Alp
The following problem is considered: Given a multivariable system with m inputs and r outputs and an m x r matrix whose nonnegative (i,j)’th element represents the cost of setting up a feedback link from the j ’th output to the i’th input, find a set of feedback links with minimum total cost, which does not give rise to fixed modes. Utilizing the graph-theoretic characterization of structurally fixed modes, the problem is decomposed into two subproblems, which are then solved by using concepts and results from network theory. The combination of the optimum solutions of the subproblems provides a suboptimal solution to the original problem.