IEEE Transactions on Automatic Control, Vol.62, No.9, 4827-4833, 2017
On Minimizing the Maximal Characteristic Frequency of a Linear Chain
We consider a linear chain of masses, each coupled to its two nearest neighbors by elastic springs. The maximal characteristic frequency of this dynamical system is a strictly convex function of certain parameters that depend on the masses and spring elasticities. Minimizing the maximal characteristic frequency under an affine constraint on these parameters is thus a convex optimization problem. For a homogeneous affine constraint, we prove that themass and elasticity values thatminimize the maximal characteristic frequency have a special structure: They are symmetric with respect to the middle of the chain and the optimal masses [spring elasticities] increase [decrease] toward the center of the chain. Intuitively speaking, this means that in order to minimize the maximal characteristic frequency we need to "fix" the center of the chain, by increasing [decreasing] the masses [spring elasticities] there. We further show that minimizing the maximal characteristic frequency of the linear chain is equivalent to maximizing the steady-state protein production rate in an important model from systems biology called the ribosome flow model.
Keywords:Characteristic frequency;convex optimization;eigenvalue optimization;mass-spring chain;maximizing protein production rate;ribosome flow model (RFM);sensitivity analysis