[en] In order to achieve ignition successfully, the thickness uniformity of the ice layer more than 99% and root mean square of the surface roughness less than 1 μm are required in the ICF cryogenic target system. Analytical calculations indicate that a maximum temperature difference of target surface less than 0.1 mK can meet the above ignition requirements. In this paper, a 3D spherical hohlraum cryogenic target model was established to study the influence of radiation on the temperature field of the system. The results show that in comparison with cylindrical target hohlraum, the spherical hohlraum has more uniform temperature distribution due to its spherical geometry. In addition, the temperature of the window-side capsule is higher than the other side due to the external radiation. The higher the radiation temperature is, the higher the absolute temperature of the capsule surface is. To avoid deterioration of the DT ice uniformity, multi-layer shield structure should be used to reduce the influence of the high excessive radiation temperature. When laser sealing film absorption rate is greater than 0.2, the surface temperature of the target significantly increases. (authors)

[en] The self-assembling process near the three-phase contact line of air, water and vertical substrate is widely used to produce various kinds of nanostructured materials and devices. We perform an in-situ observation on the self-assembling process in the vicinity of the three phase contact line. Three kinds of aggregations, i.e. particle-particle aggregation, particle-chain aggregation and chain-chain aggregation, in the initial stage of vertical deposition process are revealed by our experiments. It is found that the particle-particle aggregation and the particle-chain aggregation can be qualitatively explained by the theory of the capillary immersion force and mirror image force, while the chain-chain aggregation leaves an opening question for the further studies. The present study may provide more deep insight into the self-assembling process of colloidal particles

[en] We study the macroscopic drying patterns of aqueous suspensions of colloidal silica spheres. It was found that convection strength can influence pattern formation. Uniformed films are obtained at weaker convection strength. In addition, we make clear that it is not reasonable to discuss individually the effect of temperature and humidity on the colloid self-assembly. The physical mechanism is that these factors have relationship with the evaporation rate, which can affect the convection strength

[en] We theoretically propose a scheme to realize the dynamic control of the properties of the terahertz (THz) rainbow trapping effect (RTE) based on a silicon-filled graded grating (SFGG) in a relatively broad band via optical pumping. Through the theoretical analysis and finite-element method simulations, it is conceptually demonstrated that the band of the RTE can be dynamically tuned in a range of ∼0.06 THz. Furthermore, the SFGG can also be optically switched between a device for the RTE and a waveguide for releasing the trapped waves. The results obtained here may imply applications for the tunable THz plasmonic devices, such as on-chip optical buffers, broad band slow-light systems, and integrated optical filters. (paper)

[en] When a p- or s-polarized wave illuminates an optical system, strong inhibition of reflection can be observed at specific incident angles. Because this phenomenon does not strictly meet the definition of a classical Brewster effect, it is known as a generalized Brewster effect (GBE). Based on the fact that the graphene conductivity in the terahertz (THz) range can be dynamically modulated by optical pumping, we propose a new way to tune THz GBE in a graphene/substrate system via modulation light. A theoretical framework for the THz responses in the system tuned by modulation light has been established. We demonstrate the potential of graphene/dielectric structure as an optically tunable platform for GBE. Furthermore, we find that the tunable GBE predicted here can be classified into two categories according to physical mechanisms. One is due to the destructive interference which can be changed through tuning the modulation light. The other comes from the inhibition of the waves radiated by induced dipoles in their oscillation direction, which is dependent on the modulation light. The results obtained here can be extended to GBE systems based on other two-dimensional materials and be applied to the realization of new types of graphene-based devices. (paper)

[en] A micro-manufacturing technology is presented to form three-dimensional metallic micro-structures directly. Micro grid array structures are replicated on a metallic foil surface, with high spatial resolution in micron levels. The numerical simulation results indicate that the material deformation process is characterized by an ultrahigh strain rate. With increasing pulse duration, the sample absorption strain energy increases, and the sample deformation degree enlarges. The stress state of the central point fluctuates between tensile stress and compression stress. The stress state of the angular point is altered from compressive stress to tensile stress due to geometry and loading conditions. The duration length of pulse stress has an effect on the stress state, as with the increase of pulse duration, fluctuation in the stress state decreases. Therefore, laser micro-manufacturing technology will be a potential laser micro forming method which is characterized by low cost and high efficiency. (fundamental areas of phenomenology(including applications))

[en] Cryogenic target is one of the critical component in inertial confinement fusion, which is assembled inside a hohlraum needed to be filled by fill tubes. In this paper, a microchannel model is established based on the analysis of the big difference between the microchannel and the conventional channel on flow and heat transfer characteristics. The modeling is implemented with FLUENT software and the correction of Navier-Stokes equations is inserted through UDF. From the results of simulation, the effect of gravity can be neglected while that of surface tension should be taken into consideration. Velocity slip and temperature jump are also calculated for their significant influence on flow and heat transfer in the microchannel. Three different fill tube models are compared to provide a suitable type for experiment design. Choosing different boundary conditions, certain filling of fuel could be confirmed. During the filling process, the temperature and pressure of inlet should be increased gradually with the increasing temperature and pressure of outlet to guarantee continuous controlled filling. (authors)

[en] By using a finite difference time domain (FDTD) method, the effects of a one-dimensional (1D) surface defect on designer surface plasmon polaritons (designer SPPs) supported by a 1D metallic grating in THz domain are investigated. When the size of the defect is in a special range which is not too large, the designer SPPs reflected and scattered by the defect are weak enough to be neglected. The defect only induces a disturbance in the energy distribution of the designer SPP supported by the whole defect grating. If the defect size exceeds the said range, the reflecting and scattering are dominant in the influences of the defect on designer SPPs. Our analysis opens opportunities to control and direct designer SPPs by introducing a 1D defect, especially in low frequency domain. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

[en] Highlights: • Two-dimensional numerical model with different tube shapes is established. • Error between simulation and experiment on heat transfer coefficient is within 9.5%. • Distribution of film thickness and velocity along four tubes are revealed. • Heat transfer characteristics of four tubes are compared. -- Abstract: Horizontal tube falling film evaporators are widely used in refrigeration and chemical industry. Two-dimensional numerical model with different tube shapes is established in this paper to simulate heat and mass transfer process with CFD method, and the heat transfer coefficient of simulation is also validated by experimental data. Flow and heat transfer characteristics of falling film evaporation on a circular tube and three flat tubes are investigated, respectively. It is confirmed that the liquid film becomes thinner and thinner as height-width ratio increases and average film thickness of three flat tubes is nearly 2.9–16.5% smaller than that of circular tube 1. Additionally, the cross sections of flat tube have a lower dimensionless temperature and a thinner thermal boundary layer, which means a better heat transfer performance compared with the circular tube 1. The average heat transfer coefficient of three flat tubes is approximately 2.2%, 4.2% and 11.2% higher than that of the circular tube, respectively.

[en] To realize intelligent obstacle avoidance and local path decisions for maritime autonomous surface ships (MASS) in uncertain environments, a navigation behavioural decision-making model based on deep reinforcement learning (DRL) algorithm improved by artificial potential field (APF) is proposed. Based on the analysis of navigation decision system and perception principle, the action space, reward function, motion search strategy and action value function are designed respectively for the purpose of steering to collision avoidance. The navigation behavioural decision-making model for MASS is improved by adding the prior information, the gravitational potential field and the obstacle repulsion potential field to update the initial action state value function and search path. Python and Pygame modules are used to build a simulation chart. Effectiveness of the algorithm is verified, with Tianjin Xingang port as a study case. The simulation results show that the APF-DRL algorithm is better than the DRL algorithm in training iteration time and piloting decision path, which improves the self-learning ability of MASS, and can meet the requirements of MASS path decision and adaptive obstacle avoidance. (paper)