Collaborative Route Planning of UAVs, Workers and Cars for Crowdsensing in Disaster Response

Efficiently obtaining the up-to-date information in the disaster-stricken area is the key to successful disaster response. Unmanned aerial vehicles (UAVs), workers and cars can collaborate to accomplish sensing tasks, such as data collection, in disaster-stricken areas. In this paper, we explicitly address the route planning for a group of agents, including UAVs, workers, and cars, with the goal of maximizing the task completion rate. We propose MANF-RL-RP, a heterogeneous multi-agent route planning algorithm that incorporates several efficient designs, including global-local dual information processing and a tailored model structure for heterogeneous multi-agent systems. Global-local dual information processing encompasses the extraction and dissemination of spatial features from global information, as well as the partitioning and filtering of local information from individual agents. Regarding the construction of the model structure for heterogeneous multi-agent, we perform the following work. We design the same data structure to represent the states of different agents, prove the Markovian property of the decision-making process of agents to simplify the model structure, and also design a reasonable reward function to train the model. Finally, we conducted detailed experiments based on the rich simulation data. In comparison to the baseline algorithms, namely Greedy-SC-RP and MANF-DNN-RP, MANF-RL-RP has exhibited a significant improvement in terms of task completion rate

Reply to: Low-frequency quantum oscillations in LaRhIn5_5: Dirac point or nodal line?

We thank G.P. Mikitik and Yu.V. Sharlai for contributing this note and the cordial exchange about it. First and foremost, we note that the aim of our paper is to report a methodology to diagnose topological (semi)metals using magnetic quantum oscillations. Thus far, such diagnosis has been based on the phase offset of quantum oscillations, which is extracted from a "Landau fan plot". A thorough analysis of the Onsager-Lifshitz-Roth quantization rules has shown that the famous $\pi$-phase shift can equally well arise from orbital- or spin magnetic moments in topologically trivial systems with strong spin-orbit coupling or small effective masses. Therefore, the "Landau fan plot" does not by itself constitute a proof of a topologically nontrivial Fermi surface. In the paper at hand, we report an improved analysis method that exploits the strong energy-dependence of the effective mass in linearly dispersing bands. This leads to a characteristic temperature dependence of the oscillation frequency which is a strong indicator of nontrivial topology, even for multi-band metals with complex Fermi surfaces. Three materials, Cd$_3$As$_2$, Bi$_2$O$_2$Se and LaRhIn$_5$ served as test cases for this method. Linear band dispersions were detected for Cd$_3$As$_2$, as well as the $F$ $\approx$ 7 T pocket in LaRhIn$_5$.Comment: Response to Matter arising for Nature Communications 12, 6213 (2021

Fingerprint of topology in quantum oscillations at elevated temperatures

A versatile methodology to detect Dirac or Weyl fermions in topological semimetals by transport or thermodynamic measurements remains an open problem. It is often argued that a $\pi$ phase shift in quantum oscillations directly corresponds to the Berry phase of topological semimetals. However, the oscillation phase is complicated by multiple contributing factors including the orbital magnetic moment, rendering such correspondences ambiguous for a substantial fraction of topological semimetals. Here we propose the temperature dependence of the frequency, ${F}(T)$, rather than the oscillation phase, as a hallmark signature of topology in quantum oscillations. At temperatures comparable to the cyclotron energy, $F(T)$ encodes the energy-derivative of the cyclotron mass -- a quantity that vanishes for conventional Schr\"odinger-type fermions, yet equals the inverse square of the Fermi velocity for Dirac/Weyl fermions. We experimentally observe this temperature dependent frequency in the Dirac semimetal Cd$_3$As$_2$, and quantitatively describe it by a fitting-parameter-free model of Dirac Fermions. It is absent in the topologically trivial metal Bi$_2$O$_2$Se as expected while the material shows a $\pi$ shift of the quantum oscillation phase without any topological origin. We further identify Dirac fermions in LaRhIn$_5$, despite their co-existence with multiple, topologically trivial Fermi pockets contributing the vast majority of transport carriers. This approach requires no ab-initio calculation as input, and is able to identify topological Fermi pockets which are small compared to the Brillouin-zone volume -- both attributes being ideally suited to identify the topological character of heavy fermion materials