A novel and efficient approach for the numerical solution of time-dependent coupled-wave equations, which are frequently used for the modeling of distributed-feedback, distributed Bragg reflector, ...and Fabry-Perot laser diodes, is proposed. In this approach, the coupled-wave equations are split into two sets of equations. One of two sets of equations contains only the phase factors and time derivatives, and the other contains only the coupling terms. The separate sets of equations are solved exactly in their split form successively. This new numerical scheme, which we call the split-step time-domain model, is found to require an order of magnitude smaller number of subsections to get more accurate results than previous methods while the computation time for each time step is comparable to previous methods.
The reflection properties of a coupled-ring reflector (CRR) are analyzed using the transfer matrix method. The CRR is composed of two coupled rings that are coupled to a bus waveguide. Depending on ...the combination of the cross-coupling ratios of the couplers, the reflection spectrum shape changes greatly. In the lossless case, the reflection spectrum has four peaks when the ring-bus coupling ratio is small. When the ring-bus coupling ratio is more than half and the ring-ring coupling is very small, the four peaks broaden, forming a single peak with still considerably narrow reflection spectrum, which makes the CRR attractive in applications requiring compact reflectors such as for single-mode laser diodes. The dependence of the propagation and insertion losses of the couplers on the reflection spectrum is also investigated, and the design guidelines are presented.
In this paper, a unified framework for exploration in reinforcement learning (RL) is proposed based on an option-critic model. The proposed framework learns to integrate a set of diverse exploration ...strategies so that the agent can adaptively select the most effective exploration strategy over time to realize a relevant exploration-exploitation trade-off for each given task. The effectiveness of the proposed exploration framework is demonstrated by various experiments in the MiniGrid and Atari environments.
The influence of HCl on the oxidation of gaseous elemental mercury (Hg
0) has been investigated using a dielectric barrier discharge (DBD) plasma process, where the temperature of the plasma reactor ...and the composition of gas mixtures of HCl, H
2O, NO, and O
2 in N
2 balance have been varied. We observe that Cl atoms and Cl
2 molecules, created by the DBD process, play important roles in the oxidation of Hg
0 to HgCl
2. The addition of H
2O to the gas mixture of HCl in N
2 accelerates the oxidation of Hg
0, although no appreciable effect of H
2O alone on the oxidation of Hg
0 has been observed. The increase of the reaction temperature in the presence of HCl results in the reduction of Hg
0 oxidation efficiency probably due to the deterioration of the heterogeneous chemical reaction of Hg
0 with chlorinated species on the reactor wall. The presence of NO shows an inhibitory effect on the oxidation of Hg
0 under DBD of 16% O
2 in N
2, indicating that NO acts as an O and O
3 scavenger. At the composition of Hg
0 (280
μg
m
−3), HCl (25
ppm), NO (204
ppm), O
2 (16%) and N
2 (balance) and temperature 90
°C, we obtain the nearly complete oxidation of Hg
0 at a specific energy density of 8
J
l
−1. These results lead us to suggest that the DBD process can be viable for the treatment of mercury released from coal-fired power plants.
The oxidation of gas phase elemental mercury (Hg
0) by atmospheric pressure non-thermal plasma has been investigated at room temperature, employing both dielectric barrier discharge (DBD) of the gas ...mixture of Hg
0 and injection of ozone (O
3) into the gas mixture of Hg
0. Results have shown that the oxidative efficiencies of Hg
0 by DBD and the injection of O
3 are 59% and 93%, respectively, with energy consumption of 23.7
J
L
−1. This combined approach has indicated that O
3 plays a decisive role in the oxidation of gas phase Hg
0. Also the oxidation of Hg
0 by injecting O
3 into the gas mixture of Hg
0 proceeds with better efficiency than DBD of the gas mixture of Hg
0. These results have been explained by the incorporation of the competitive reaction pathways between the formation of HgO by O
3 and the decomposition of HgO back to Hg
0 in the plasma environment.
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