Under the background of climate change, freeze–thaw patterns tend to be turbulent: ecosystem function processes and their mutual feedback mechanisms with microorganisms in sensitive areas around the world are currently a hot topic of research. We studied changes of soil properties in alpine wetlands located in arid areas of Central Asia during the seasonal freeze–thaw period (which included an initial freezing period, a deep freezing period, and a thawing period), and analyzed changes in soil bacterial community diversity, structure, network in different stages with the help of high-throughput sequencing technology. The results showed that the α diversity of the soil bacterial community showed a continuous decreasing trend during the seasonal freeze–thaw period. The relative abundance of dominant bacterial groups (Proteobacteria (39.04%–41.28%) and Bacteroidota (14.61%–20.12%)) did not change significantly during the freeze–thaw period. At the genus level, different genera belonging to the same phylum dominated in different stages, or there were clusters of genera belonging to different phylum. For example, g_Ellin6067, g_unclassified_f_Geobacteraceae, g_unclassified_f_Gemmatimonadaceae coexisted in the same cluster, belonging to Proteobacteria, Desulfobacterota and Gemmatimonadota respectively, and their abundance increased significantly during the freezing period. This "adaptive freeze–thaw" phylogenetic model suggests a heterogeneous stress resistance of bacteria during the freeze–thaw period. In addition, network analysis showed that, although the bacterial network was affected to some extent by environmental changes during the initial freezing period and its recovery in the thawing period lagged behind, the network complexity and stability did not change much as a whole. Our results prove that soil bacterial communities in alpine wetlands are highly resistant and adaptive to seasonal freeze–thaw conditions. As far as we know, compared with short-term freeze–thaw cycles research, this is the first study examining the influence of seasonal freeze–thaw on soil bacterial communities in alpine wetlands. Overall, our findings provide a solid base for further investigations of biogeochemical cycle processes under future climate change.
According to the requirements of monitoring high-voltage equipment and monitoring leakage current of MOVs in series capacitors, double core compensation methods was adopted in this paper, and large window or diameter of micro-current sensor was developed. The developed sensor coil has an outer diameter D=160mm, an inner diameter d=120mm, and a thickness H=10mm. The maximum measurement error is −2.9% in the range of 0.2mA to 5mA. It is difficult for the sensor to measure the current below 0.2mA, because of the interference of background noise. Using the same compensation circuit, the larger the diameter of sensor will be, the worse the measurement accuracy will be. The transient voltage suppressor (TVS) and thyristor surge protection device (TSPD) were adopted in the aspect of impulse current protection design. The test results showed that the sensor developed worked normally under the impact of 8/20µs1@10kA and 2mA@2.5kA square wave and after the test the measured amplitude was still accurate. The sensor presented various of transient processes under the impact of 8/20µs and 2ms square wave current. The sensor had certain ability of self-recovery and self-adjustment, and it can be restored to normal after about 120ms~ 165ms. The transient process of the sensor is related to the material, dimension of the core, coil turns and the dynamic characteristics of the compensation circuit.
Abstract Conditioning alkaline soil with acidic phosphorus-rich biochar might contribute to achieving sustainable phosphorus (P) use and residue management. In this study, acidic phosphorus-rich biochar was prepared from halophyte species biochar (HBC) by the modification of H 3 PO 4 (P-HBC) and H 4 P 2 O 7 (PA-HBC). The P combination method and fractions in biochars were characterized, and the effects of biochars on P fractions in different types of alkaline soil were examined with incubation experiments. The results showed that the pH values of P-HBC (3.31) and PA-HBC (2.17) decreased significantly, and the total P content increased to 4.66 g·kg − 1 and 5.24 g·kg − 1 , respectively. The spectral analysis confirmed the doping of P and acid groups in biochar. The addition of modified biochars in alkaline soils will makes the soil tend to be neutral. Sequential extraction of soil P confirmed that biochars application facilitated the transformation of stable P into active fractions, with greater effects from modified biochars than HBC. Activation mechanism of biochar to soil P fractions varies from soil types. Overall, acidic phosphorus-rich biochars can be employed to improve alkaline soil properties and increase P activity.
Collaborative autonomous multi-agent systems covering a specified area have many potential applications, such as UAV search and rescue, forest fire fighting, and real-time high-resolution monitoring. Traditional approaches for such coverage problems involve designing a model-based control policy based on sensor data. However, designing model-based controllers is challenging, and the state-of-the-art classical control policy still exhibits a large degree of sub-optimality. In this paper, we present a reinforcement learning (RL) approach for the multi-agent efficient domain coverage problem involving agents with second-order dynamics. Our approach is based on the Multi-Agent Proximal Policy Optimization Algorithm (MAPPO). Our proposed network architecture includes the incorporation of LSTM and self-attention, which allows the trained policy to adapt to a variable number of agents. Our trained policy significantly outperforms the state-of-the-art classical control policy. We demonstrate our proposed method in a variety of simulated experiments.
Get PDF Email Share Share with Facebook Tweet This Post on reddit Share with LinkedIn Add to CiteULike Add to Mendeley Add to BibSonomy Get Citation Copy Citation Text C. Wang, M. Chen, and Z. Meng, "Phase Noise Reduction of a Compact Brillouin/Erbium Fiber Laser," in Asia Pacific Optical Sensors Conference, OSA Technical Digest (online) (Optica Publishing Group, 2016), paper JF2A.6. Export Citation BibTex Endnote (RIS) HTML Plain Text Citation alert Save article
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