In recent years, many researches focus on sound source localization based on neural networks, which is an appealing but difficult problem. In this paper, a novel time-domain end-to-end method for sound source localization is proposed, where the model is trained by two strategies with both cross entropy loss and mean square error loss. Based on the idea of multi-task learning, CNN is used as the shared hidden layers to extract features and DNN is used as the output layers for each task. Compared with SRP-PHAT, MUSIC and a DNN-based method, the proposed method has better performance.
The performance of perovskite solar cells (PSCs) depends on the crystallization of the perovskite layer. Herein, we demonstrate an effective photoannealing (PA) process by a halogen lamp. During the PA process, on the one hand, the lower energy photon, that is, near IR up to similar to 1015 nm photon, drives the crystallization of the perovskite film, similar to the conventional thermal annealing (TA). On the other hand, the higher energy photon of PA can excite the trapped carriers and release the space charges, thus leading to an ideal perovskite layer with better crystallinity and lower density of defect when compared to that of TA. A maximum power conversion efficiency (PCE) has been obtained to be 20.41% in the CH3 NH3 PbI3 -based planar PSCs based on PA because of the increase of J(sc) and V-oc, much higher than the control device based on the conventional TA with a maximum PCE of 18.08%. Therefore, this result demonstrates that PA is an effective method to promote the device performances and reduce the fabrication cost, which provides a potential approach for the commercial application of perovskite devices.
Managing reactive nitrogen (N-r) to achieve a sustainable balance between production of food, feed and fiber, and environmental protection is a grand challenge in the context of an increasingly affluent society. Here, we propose a novel framework for national nitrogen (N) assessments enabling a more consistent comparison of the uses, losses and impacts of N-r between countries, and improvement of N-r management for sustainable development at national and regional scales. This framework includes four key components: national scale N budgets, validation of N fluxes, cost-benefit analysis and N-r, management strategies. We identify four critical factors for Nr management to achieve the sustainable development goals: N use efficiency (NUE), N-r recycling ratio (e.g., ratio of livestock excretion applied to cropland), human dietary patterns and food waste ratio. This framework was partly adopted from the European Nitrogen Assessment and now is successfully applied to China, where it contributed to trigger policy interventions toward improvements for future sustainable use of N-r. We demonstrate how other countries can also benefit from the application our framework, in order to include sustainable N-r management under future challenges of growing population, hence contributing to the achievement of some key sustainable development goals (SDGs).
Deciphering the sources of metals is a prerequisite to establishing genetic models of ore formation, and is of importance for developing exploration models. For most magmatic-hydrothermal deposits, non-magmatic sourced components (e.g., fluids, sulfur and metals) are suggested to have minor or negligible contributions. On the other hand, there is substantial evidence to indicate that external ore-forming components could be crucial for the mineralization of some magmatic-hydrothermal deposits. Here, we conduct a detailed pyrite sulfur and lead isotope study on the Xinqiao stratabound deposit, South China, with the aim of constraining the contributions of ore-forming components from sedimentary rocks and existing mineralization through water-rock interaction. Traditionally, the source of mineralization at Xinqiao is debated. For example, a Cretaceous magmatic-hydrothermal origin was proposed as the sole source of metals. In sharp contrast, a Carboniferous sedimentary sulfide layer as proto-ore, which was enriched later by the Cretaceous magmatic-hydrothermal fluids, is required in a remobilization model. Crystallized pyrite grains from the stratabound orebody (pyl) have a delta S-34 value of 4.09 +/- 1.42 parts per thousand (2 SD), which is similar to that of pyrite grains from the garnet bearing skarn ore (py3). Colloform pyrite ore, which is composed of fine-grained (similar to 500 nm) cubic pyrite grains (py2a), has a delta S-34 value of 0.20 +/- 1.14 parts per thousand. The sulfur isotope composition of pyrite grains from the sandstone hosted quartz-pyrite veins is bimodal with delta S-34 values of 3.28 +/- 6.46 parts per thousand (py4a) and -11.87 +/- 5.43 parts per thousand (py4b). The Pb isotope compositions ((206)/(204)pb approximate to 18.5, (207)/Pb-204 approximate to 15.5) of pyl, py4a and py4b are broadly the same as that of K-feldspar ro from the Cretaceous Jitou diorite, while py2a are more radiogenic ((206)/Pb-204 approximate to 21.5, (207)/(204) Pb approximate to, ro = 18). Our pyrite S and Pb isotope data show no support for the presence of a Carboniferous sedimentary sulfide layer as proto-ore, but instead suggest that leaching sulfur and metals from Permian shales and an unexposed mineralization through water-rock interaction is a vital mechanism for the mineralization at Xinqiao. In line with previous studies, contributions from the late Permian shales are complementary for the stratabound orebody, and recycling existing Mo-Au rich mineralization is key for the formation of sandstone hosted gold rich pyrite-quartz veins. The existing mineralization is not exposed yet, and should be considered in future mineral exploration. Limited sulfur isotope fractionation between pyl, py2 and py3 (0-4 parts per thousand) further indicates a relatively reducing condition during their formation, while significant lower sulfur isotope composition (delta S-34 = 012 parts per thousand) of py4 could imply an oxidizing condition during its formation. Our study highlights that detailed in-situ sulfur and lead isotope analyses under robust geological and petrographic frameworks can tightly constrain the source of ore forming components, yield insights into oxygen fugacity during ore formation, and offer clues for future mineral exploration.
Current technologies could identify the abundance and functions of specific microbes, and evaluate their individual effects on microbial ecology. However, these microbes interact with each other, as well as environmental factors, in the form of complex network. Determination of their combined ecological influences remains a challenge. In this study, we developed a tripartite microbial-environment network (TMEN) analysis method that integrates microbial abundance, metabolic function, and environmental data as a tripartite network to investigate the combined ecological effects of microbes. Applying TMEN to analyzing the microbial-environment community structure in the sediments of Hangzhou Bay, one of the most seriously polluted coastal areas in China, we found that microbes were well-organized into 4 bacterial communities and 9 archaeal communities. The total organic carbon, sulfate, chemical oxygen demand, salinity, and nitrogen-related indexes were detected as crucial environmental factors in the microbial-environmental network. With close interactions with these environmental factors, Nitrospirales and Methanimicrococcu were identified as hub microbes with connection advantage. Our TMEN method could close the gap between lack of efficient statistical and computational approaches and the booming of large-scale microbial genomic and environmental data. Based on TMEN, we discovered a potential microbial ecological mechanism that crucial species with significant influence on the microbial community ecology would possess one or two of the community advantages for enhancing their ecological status and essentiality, including abundance advantage and connection advantage.
Partial flattening of the spatially extended molecular scaffold has been employed as an effective tactic to improve the device performance of a perylenediimide (PDI)-based small-molecule acceptor because the less twisted yet not completely planar molecular geometry is anticipated to improve the molecular packing and thereby attain a more suitable balance between the carrier transport ability and phase domain size. A small-molecule acceptor BF-PDI comprising four alpha-substituted PDI units attached around a 9,9'-bifluorenylidene (BF) central moiety is designed and studied in polymer solar cells. The BF group is deemed a ring-fused analogue of the tetraphenylethylene (TPE) unit. Due to the less twisted and better conjugated BF skeleton, BF-PDI displays more delocalized lowest unoccupied molecular orbital. By virtue of both the electronic and steric effects, BF-PDI is suggested to bring about superior intermolecular stacking and donor-acceptor phase separation morphology in blend films. Indeed, the experimental results show that BF-PDI displays improved charge transport ability and a higher power-conversion efficiency of 8.05% than that of TPE-PDI. Grazing-incidence wide-angle X-ray diffraction and resonant soft X-ray scattering confirm the more compact and ordered molecular packing as well as smaller domain sizes in the P3TEA/BF-PDI blend.
This study presents a comprehensive comparision between 2D and 3D hydrodynamic modeling of a pseudo-2D turbulent fluidized bed with Geldart B particle. Based on the Euler-Euler approach and the EMMS-based drag model, 2D/3D CFD models are established, their sensitivities to the restitution coefficient and the specularity coefficient are analyzed, and the 2D/3D hydrodynamic simulations are performed and compared. The simulation results show that 3D simulations are more sensitive to the restitution coefficient and the specularity coefficient than 2D simulations. At the beginning of fluidization process, 2D simulation predicts greater bubble size and higher bed expansion than 3D simulation; as a complete fluidization is achieved, 2D model exhibits higher solid concentrations in the middle transition and the upper dilute-phase regions; the fluidization process in the 2D simulation develops more quickly than that in the 3D computation. Both the 2D and 3D models could capture the global flow behavior in the bottom dense-phase region of the turbulent fluidized bed reasonably. In the middle and upper regions, however, the 2D model overestimates the solid concentration and particle velocity while the 3D simulation gives better hydrodynamic prediction. For the present pseudo-2D turbulent fluidized bed with Geldart B particle, the bottom dense-phase region resembles 2D flow and 2D simulations may be adequate; however, the middle and upper regions exhibit 3D flow and full 3D simulations are needed.