155 research outputs found
Model predictive control-based value estimation for efficient reinforcement learning
Reinforcement learning suffers from limitations in real practices primarily
due to the numbers of required interactions with virtual environments. It
results in a challenging problem that we are implausible to obtain an optimal
strategy only with a few attempts for many learning method. Hereby, we design
an improved reinforcement learning method based on model predictive control
that models the environment through a data-driven approach. Based on learned
environmental model, it performs multi-step prediction to estimate the value
function and optimize the policy. The method demonstrates higher learning
efficiency, faster convergent speed of strategies tending to the optimal value,
and fewer sample capacity space required by experience replay buffers.
Experimental results, both in classic databases and in a dynamic obstacle
avoidance scenario for unmanned aerial vehicle, validate the proposed
approaches
UAV Pathfinding in Dynamic Obstacle Avoidance with Multi-agent Reinforcement Learning
Multi-agent reinforcement learning based methods are significant for online
planning of feasible and safe paths for agents in dynamic and uncertain
scenarios. Although some methods like fully centralized and fully decentralized
methods achieve a certain measure of success, they also encounter problems such
as dimension explosion and poor convergence, respectively. In this paper, we
propose a novel centralized training with decentralized execution method based
on multi-agent reinforcement learning to solve the dynamic obstacle avoidance
problem online. In this approach, each agent communicates only with the central
planner or only with its neighbors, respectively, to plan feasible and safe
paths online. We improve our methods based on the idea of model predictive
control to increase the training efficiency and sample utilization of agents.
The experimental results in both simulation, indoor, and outdoor environments
validate the effectiveness of our method. The video is available at
https://www.bilibili.com/video/BV1gw41197hV/?vd_source=9de61aecdd9fb684e546d032ef7fe7b
Ground state solutions for a quasilinear Kirchhoff type equation
We study the ground state solutions of the following quasilinear Kirchhoff type equation
where and is a positive parameter. Under some suitable conditions on we obtain the existence of ground state solutions of the above equation with $1<p<11.
Microfiber-based inline Mach-Zehnder interferometer for dual-parameter measurement
An approach to realizing simultaneous measurement of refractive index (RI) and temperature based on a microfiber-based dual inline Mach-Zehnder interferometer (MZI) is proposed and demonstrated. Due to different interference mechanisms, as one interference between the core mode and the lower order cladding mode in the sensing single-mode fiber and the other interference between the fundamental mode and the high-order mode in the multimode microfiber, the former interferometer achieves RI sensitivity of -23.67 nm/RIU and temperature sensitivity of 81.2 pm/oC, whereas those of the latter are 3820.23 nm/RIU, and -465.7 pm/oC, respectively. The large sensitivity differences can provide a more accurate demodulation of RI and temperature. The sensor is featured with multiparameters measurement, compact structure, high sensitivity, low cost, and easy fabrication
Refractive index sensitivity characteristics near the dispersion turning point of the multimode microfiber-based Mach–Zehnder interferometer
The turning point of the refractive index (RI) sensitivity based on the multimode microfiber (MMMF) in-line Mach–Zehnder interferometer (MZI) is observed. By tracking the resonant wavelength shift of the MZI generated between the HE11 and HE12 modes in the MMMF, the surrounding RI (SRI) could be detected. Theoretical analysis demonstrates that the RI sensitivity will reach ±∞ on either side of the turning point due to the group effective RI difference (퐺) approaching zero. Significantly, the positive sensitivity exists in a very wide fiber diameter range, while the negative sensitivity can be achieved in a narrow diameter range of only 0.3 μm. Meanwhile, the experimental sensitivities and variation trend at different diameters exhibit high consistency with the theoretical results. High RI sensitivity of 10777.8 nm/RIU (RI unit) at the fiber diameter of 4.6 μm and the RI around 1.3334 is realized. The discovery of the sensitivity turning points has great significance on trace detection due to the possibility of ultrahigh RI sensitivity
Graphene-assisted microfiber for optical-power-based temperature sensor
Combined the large evanescent field of microfiber with the high thermal conductivity of graphene, a sensitive all-fiber temperature sensor based on graphene-assisted micro fiber is proposed and experimentally demonstrated. Microfiber can be easily attached with graphene due to the electrostatic 6 force, resulting in an effective interaction between graphene and the evanescent field of microfiber. The change of the ambient temperature has a great influence on the conductivity of graphene, leading to the variation of the effective refractive index of microfiber. Consequently, the optical power transmission will be changed. The temperature sensitivity of 0.1018 dB/°C in the heating process and 0.1052 dB/°C in the cooling process as well as a high resolution of 0.0098 °C is obtained in the experiment. The scheme may have great potential in sensing fields owing to the advantages of high sensitivity, compact size, and low cost
Controllable group delay in a θ-shaped microfiber resonator with coupled-resonator-induced transparency
The control of Light velocity is theoretically and experimentally demonstrated in a θ-shaped microfiber resonator with coupled-resonator-induced transparency. By adjusting the structure parameters, group delays from -60ps to 200ps are achieved in the all-fiber resonator
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