Neutron tomography is gaining popularity particularly in cultural heritage research, for non-destructively analysing the inner structure of bulk metal artefacts, such as bronzes, but the induced temporary decay radiation is often considered as a drawback. However, this delayed gamma-emission can be put to good use: by performing gamma spectroscopy after neutron tomography, the interior elemental composition of artefacts can be obtained “for free”. Inspired by this, we propose a ray-tracing approach to non-invasively quantify both interior geometry and elemental composition using only a single neutron tomography experiment. This strategy aligns well with both the aim for efficient use of neutron beam time and the expectation from curators and conservators for minimal neutron irradiation. Here, we outline the core principle of this method, demonstrate the extent of its quantification capability on bulk objects of known composition by fusing neutron tomography and delayed-gamma spectroscopy data sets. We also showcase its practical application on an ancient solid-cast Indonesian bronze statuette, by which we gain insights into how the pristine inner bronze segregated into a different composition than the surrounding shell. Similarly, the method allows us to quantify the composition of a hidden offering in the statuette that consecrates the bronze for worship purposes.

For a small low-cost Unmanned Aerial Vehicle (UAV), the accurate aerodynamics and flight dynamics characteristics wouldn't be obtained easily, and the control coupling is serious, so the robustness of its flight controller must be considered carefully. In order to solve the problem, a Lateral-Directional (Lat-Dir) flight control method based on Deep Reinforcement Learning (DRL) are proposed in this paper. Firstly, based on the nominal state, three control laws are designed: classical Proportional Integral Derivative (PID) control, Linear Quadratic Gaussian (LQG) control based on modern control theory, and Deep Reinforcement Learning (DRL) control based on Twin Delayed Deep Deterministic Policy Gradient (TD3) method. In order to solve the problem of incomprehensible physical meaning of neural network in DRL, a simplified control strategy network is derived based on the inspiration of PID controller. In order to solve the problem that the reward function of DRL is difficult to be determined, the weights of the optimal quadratic function designed by LQG method are adopted, and the weights of control output considering discretization is added also. Then, the three controller are applied to nominal flight state and deviation state respectively, and the numerical flight simulation is carried out. The results show that, in the nominal state, the performance of DRL is close to the LQG and better than the PID. In the deviation state, which the lateral and directional static stable derivatives are changed artificially from stable to neutral stable, the rise time and adjustment time of the DRL change slightly, while the LQG degrades seriously and appears instable, and it is proved that the proposed DRL control method has better performance robustness.

Rechargeable aqueous zinc-ion batteries (ZIBs) are promising for cheap stationary energy storage. Challenges for Zn-ion insertion hosts are the large structural changes of the host structure upon Zn-ion insertion and the divalent Zn-ion transport, challenging cycle life and power density respectively. Here a new mechanism is demonstrated for the VO ₂ cathode toward proton insertion accompanied by Zn-ion storage through the reversible deposition of Zn ₄ (OH) ₆ SO ₄ ·5H ₂ O on the cathode surface, supported by operando X-ray diffraction, X-ray photoelectron spectroscopy, neutron activation analysis, and density functional theory simulations. This leads to an initial discharge capacity of 272 mAh g ⁻¹ at a current density of 3.0 A g ⁻¹ , of which 75.5% is maintained after 945 cycles. It is proposed that the competition between proton and Zn-ion insertion in the VO ₂ host is determined by the solvation energy of the salt anion and proton insertion energetics, where proton insertion has the advantage of minimal structural distortion leading to a long cycle life. As the discharge kinetics are capacitive for the first half of the process and diffusion limited for the second half, the VO ₂ cathode takes the middle road possessing both fast kinetics and high practical capacities revealing a reaction mechanism that provides new perspective for the development of aqueous ZIBs.