719 research outputs found
Optimal Control of a Nonlinear Time-Delay System in Batch Fermentation Process
The main control goal in batch process is to get a high yield of products. In this
paper, to maximize the yield of 1,3-propanediol (1,3-PD) in bioconversion of glycerol
to 1,3-PD, we consider an optimal control problem involving a nonlinear
time-delay system. The control variables in this problem include the initial concentrations
of biomass and glycerol and the terminal time of the batch process.
By a time-scaling transformation, we transcribe the optimal control problem into
a new one with fixed terminal time, which yields a new nonlinear system with
variable time-delay. The gradients of the cost and constraint functionals with
respect to the control variables are derived using the costate method. Then, a
gradient-based optimization method is developed to solve the optimal control
problem. Numerical results show that the yield of 1,3-PD at the terminal time
is increased considerably compared with the experimental data
SVD-based Method for Radio Frequency Interference Suppression Applied to SAR
Synthetic aperture radar (SAR) is a special type of active microwave sensor, which has got a wide range of applications in remote sensing. However, the performance of SAR systems may be affected by radio frequency interference (RFI) in several geographic regions. A novel singular value decomposition method is proposed for radio frequency interference suppression applied to SAR. This method decomposes the singular vectors of the received signal with RFI into interference subspace and signal subspace. The orthogonality of the two subspaces is used to suppress the RFI. The point-target simulation is used to show the working principle of the proposed algorithm. The experimental results based on SAR real data are also shown to verify the proposed algorithm.Defence Science Journal, 2012, 62(2), pp.132-136, DOI:http://dx.doi.org/10.14429/dsj.62.114
- …