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Guidance commands of flight vehicles can be regarded as a series of data sets having fixed time intervals; thus, guidance design constitutes a typical sequential decision problem and satisfies the basic conditions for using the deep reinforcement learning (DRL) technique. In this paper, we consider the scenario where the escape flight vehicle (EFV) generates guidance commands based on the DRL technique, while the pursuit flight vehicles (PFVs) derive their guidance commands employing the proportional navigation method. For every PFV, the evasion distance is described as the minimum distance between the EFV and the PFV during the escape-and-pursuit process. For the EFV, the objective of the guidance design entails progressively maximizing the residual velocity, which is described as the EFV's velocity when the last evasion distance is attained, subject to the constraint imposed by the given evasion distance threshold. In the outlined problem, three dimensionalities of uncertainty emerge: (1) the number of PFVs requiring evasion at each time instant; (2) the precise time instant at which each of the evasion distances can be attained; (3) whether each attained evasion distance exceeds the given threshold or not. To solve the challenging problem, we propose an innovative solution that integrates the recurrent neural network (RNN) with the proximal policy optimization (PPO) algorithm, engineered to generate the guidance commands of the EFV. Initially, the model, trained by the RNN-based PPO algorithm, demonstrates effectiveness in evading a single PFV. Subsequently, the aforementioned model is deployed to evade additional PFVs, thereby systematically augmenting the model's capabilities. Comprehensive simulation outcomes substantiate that the guidance design method based on the proposed RNN-based PPO algorithm is highly effective. [ABSTRACT FROM AUTHOR]

We integrally demonstrate 2 μm mode-locked pulses performances in all-fiber net anomalous dispersion cavity. Stable mode-locking operations with the center wavelength around 1950-1980 nm can be achieved by using the nonlinear polarization rotation structure and properly designing the dispersion management component. Conventional soliton is firstly obtained with a total anomalous dispersion cavity. Due to the contribution of commercial ultra-high numerical aperture fibers, net dispersion is reduced to -0.077 ps2. So that stretched pulse with 19.4 nm optical bandwidth is obtained and the de-chirped pulse-width can reach 312 fs using extra-cavity compression. Under pump power greater than 890 mW, stretched pulse can evolve into noise-like pulse with 41.3 nm bandwidth. The envelope and peak of such broadband pulse can be compressed with up to 2.2 ps and 145 fs, respectively. The single pulse energy of largely chirped stretched and noise-like pulse can reach 1.785 nJ and 1.53 nJ, respectively. Furthermore, extra-cavity compression can also contribute to a significant increase of peak power.