The Experts below are selected from a list of 67677 Experts worldwide ranked by ideXlab platform
N P Dover - One of the best experts on this subject based on the ideXlab platform.
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approaching the diffraction Limited Bandwidth Limited petawatt
Optics Express, 2017Co-Authors: A S Pirozhkov, Yuji Fukuda, Mamiko Nishiuchi, Hiromitsu Kiriyama, A Sagisaka, K Ogura, Michiaki Mori, Maki Kishimoto, Hironao Sakaki, N P DoverAbstract:J-KAREN-P is a high-power laser facility aiming at the highest beam quality and irradiance for performing state-of-the art experiments at the frontier of modern science. Here we approached the physical limits of the beam quality: diffraction limit of the focal spot and Bandwidth limit of the pulse shape, removing the chromatic aberration, angular chirp, wavefront and spectral phase distortions. We performed accurate measurements of the spot and peak fluence after an f/1.3 off-axis parabolic mirror under the full amplification at the power of 0.3 PW attenuated with ten high-quality wedges, resulting in the irradiance of ~1022 W/cm2 and the Strehl ratio of ~0.5.
J Nilsson - One of the best experts on this subject based on the ideXlab platform.
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optimization of phase modulation with arbitrary waveform generators for optical spectral control and suppression of stimulated brillouin scattering
Optics Express, 2015Co-Authors: Achar V Harish, J NilssonAbstract:We investigate the use of an arbitrary waveform generator to phase-modulate a laser source and externally broaden its linewidth. Through nonlinear optimization in a computer, we find modulation signals that produce top-hat-shaped optical spectra of discrete lines with highest total power within a Limited Bandwidth and Limited peak spectral power density. The required modulation Bandwidth is comparable to the targeted optical Bandwidth. Such spectra are attractive for suppressing stimulated Brillouin scattering in optical fiber. Experimentally, we generate 15 lines in a 0.5 GHz optical linewidth. However, the method can also be used to generate other optical spectra.
Jianye Hao - One of the best experts on this subject based on the ideXlab platform.
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event triggered communication network with Limited Bandwidth constraint for multi agent reinforcement learning
IEEE Transactions on Neural Networks, 2021Co-Authors: Yuanheng Zhu, Dongbin Zhao, Mengchen Zhao, Jianye HaoAbstract:Communicating agents with each other in a distributed manner and behaving as a group are essential in multi-agent reinforcement learning. However, real-world multi-agent systems suffer from restrictions on Limited Bandwidth communication. If the Bandwidth is fully occupied, some agents are not able to send messages promptly to others, causing decision delay and impairing cooperative effects. Recent related work has started to address the problem but still fails in maximally reducing the consumption of communication resources. In this article, we propose an event-triggered communication network (ETCNet) to enhance communication efficiency in multi-agent systems by communicating only when necessary. For different task requirements, two paradigms of the ETCNet framework, event-triggered sending network (ETSNet) and event-triggered receiving network (ETRNet), are proposed for learning efficient sending and receiving protocols, respectively. Leveraging the information theory, the Limited Bandwidth is translated to the penalty threshold of an event-triggered strategy, which determines whether an agent at each step participates in communication or not. Then, the design of the event-triggered strategy is formulated as a constrained Markov decision problem and reinforcement learning finds the feasible and optimal communication protocol that satisfies the Limited Bandwidth constraint. Experiments on typical multi-agent tasks demonstrate that ETCNet outperforms other methods in reducing Bandwidth occupancy and still preserves the cooperative performance of multi-agent systems at the most.
Zhao Yang Dong - One of the best experts on this subject based on the ideXlab platform.
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high performance consensus control in networked systems with Limited Bandwidth communication and time varying directed topologies
IEEE Transactions on Neural Networks, 2017Co-Authors: Guo Chen, Tingwen Huang, Zhao Yang DongAbstract:Communication data rates and energy constraints are two important factors that have to be considered in the coordination control of multiagent networks. Although some encoder–decoder-based consensus protocols are available, there still exists a fundamental theoretical problem: how can we further reduce the update rate of control input for each agent without the changing consensus performance? In this paper, we consider the problem of average consensus over directed and time-varying digital networks of discrete-time first-order multiagent systems with Limited communication data transmission rates. Each agent has a real-valued state but can only exchange binary symbolic sequence with its neighbors due to Bandwidth constraints. A class of novel event-triggered dynamic encoding and decoding algorithms is proposed, based on which a kind of consensus protocol is presented. Moreover, we develop a scheme to select the numbers of time-varying quantization levels for each connected communication channel in the time-varying directed topologies at each time step. The analytical relation among system and network parameters is characterized explicitly. It is shown that the asymptotic convergence rate is related to the scale of the network, the number of quantization levels, the system parameter, and the network structure. It is also found that under the designed event-triggered protocol, for a directed and time-varying digital network, which uniformly contains a spanning tree over a time interval, the average consensus can be achieved with an exponential convergence rate based on merely 1-b information exchange between each pair of adjacent agents at each time step.
A S Pirozhkov - One of the best experts on this subject based on the ideXlab platform.
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approaching the diffraction Limited Bandwidth Limited petawatt
Optics Express, 2017Co-Authors: A S Pirozhkov, Yuji Fukuda, Mamiko Nishiuchi, Hiromitsu Kiriyama, A Sagisaka, K Ogura, Michiaki Mori, Maki Kishimoto, Hironao Sakaki, N P DoverAbstract:J-KAREN-P is a high-power laser facility aiming at the highest beam quality and irradiance for performing state-of-the art experiments at the frontier of modern science. Here we approached the physical limits of the beam quality: diffraction limit of the focal spot and Bandwidth limit of the pulse shape, removing the chromatic aberration, angular chirp, wavefront and spectral phase distortions. We performed accurate measurements of the spot and peak fluence after an f/1.3 off-axis parabolic mirror under the full amplification at the power of 0.3 PW attenuated with ten high-quality wedges, resulting in the irradiance of ~1022 W/cm2 and the Strehl ratio of ~0.5.