Fabrication of 2D photonic crystals using block copolymer patterns on as grown LEDs.
ABSTRACT Di-block copolymer polystyrene-block-polymethyl methacrylate (PS-b-PMMA) was used to make patterns over a large area of as grown LEDs. The polymer patterns on LEDs surface could be transferred to the underlying p-GaN, the topmost layer of as grown LEDs by both reactive ion etching (RIE) and photo-enhanced chemical (PEC) etching. Removal of remaining polymer chains results in patterned LEDs which shows higher light extraction efficiency. In our experiment, much higher intensity for patterned LEDs in both photoluminescence (PL) and electroluminescence (EL) data plot were found. Similar improvements were found in I-V and L-I curves for patterned LEDs.
- SourceAvailable from: Henk A P Blom[show abstract] [hide abstract]
ABSTRACT: An important problem in filtering for linear systems with Markovian switching coefficients (dynamic multiple model systems) is the management of hypotheses, which is necessary to limit the computational requirements. A novel approach to hypotheses merging is presented for this problem. The novelty lies in the timing of hypotheses merging. When applied to the problem of filtering for a linear system with Markovian coefficients, the method is an elegant way to derive the interacting-multiple-model (IMM) algorithm. Evaluation of the IMM algorithm shows that it performs well at a relatively low computational load. These results imply a significant change in the state of the art of approximate Bayesian filtering for systems with Markovian coefficientsIEEE Transactions on Automatic Control 09/1988; · 2.72 Impact Factor
- [show abstract] [hide abstract]
ABSTRACT: Stoichiometric analysis is applied to continuous glycerol fermentation by Clostridium butyricum to calculate theoretical maximum yields and to predict preferred pathways under different conditions. The upper limits of product concentration and productivity as a function of dilution rate in continuous culture is also predicted from product inhibition kinetic. The theoretical maximum propanediol yield (0.72 mol/mol glycerol) which is calculated for a culture without hydrogen and butyric acid formation agrees well with the experimental maximum value (around 0.71 mol/mol). Comparisons of experimental results (product concentration and productivity) with theoretical calculations and those of the glycerol fermentation by Klebsiella pneumoniae reveal that the production of 1,3-propanediol by C. butyricum is far below the optimum performance available with the present strain. One of the reasons is the relatively high formation of butyric acid under the culture conditions so far applied. The distribution of reducing equivalents to propanediol and hydrogen is also suboptimal. The utilization of the reducing power from pyruvate oxidation for propanediol production is about 60–70% of the theoretical maximum under the present experimental conditions.Bioprocess and Biosystems Engineering 02/1996; 14(4):169-175. · 1.87 Impact Factor
- [show abstract] [hide abstract]
ABSTRACT: This work considers the problem of stabilization of nonlinear systems subject to state and control constraints. We propose a Lyapunov-based predictive control design that guarantees stabilization and state and input constraint satisfaction from an explicitly characterized set of initial conditions. An auxiliary Lyapunov-based analytical bounded control design is used to characterize the stability region of the predictive controller and also provide a feasible initial guess to the optimization problem in the predictive controller formulation. For the case when the state constraints are soft, we propose a switched predictive control strategy that reduces the time for which state constraints are violated, driving the states into the state and input constraints feasibility region of the Lyapunov-based predictive controller. We demonstrate the application of the Lyapunov-based predictive controller designs through a chemical process example.American Control Conference, 2005. Proceedings of the 2005; 07/2005