This paper investigates the spectrum sharing problem in vehicular networks based on multi-agent reinforcement learning, where multiple vehicle-to-vehicle (V2V) links reuse the frequency spectrum ...preoccupied by vehicle-to-infrastructure (V2I) links. Fast channel variations in high mobility vehicular environments preclude the possibility of collecting accurate instantaneous channel state information at the base station for centralized resource management. In response, we model the resource sharing as a multi-agent reinforcement learning problem, which is then solved using a fingerprint-based deep Q-network method that is amenable to a distributed implementation. The V2V links, each acting as an agent, collectively interact with the communication environment, receive distinctive observations yet a common reward, and learn to improve spectrum and power allocation through updating Q-networks using the gained experiences. We demonstrate that with a proper reward design and training mechanism, the multiple V2V agents successfully learn to cooperate in a distributed way to simultaneously improve the sum capacity of V2I links and payload delivery rate of V2V links.
In this paper, we develop a novel decentralized resource allocation mechanism for vehicle-to-vehicle (V2V) communications based on deep reinforcement learning, which can be applied to both unicast ...and broadcast scenarios. According to the decentralized resource allocation mechanism, an autonomous "agent," a V2V link or a vehicle, makes its decisions to find the optimal sub-band and power level for transmission without requiring or having to wait for global information. Since the proposed method is decentralized, it incurs only limited transmission overhead. From the simulation results, each agent can effectively learn to satisfy the stringent latency constraints on V2V links while minimizing the interference to vehicle-to-infrastructure communications.
Deep Learning in Physical Layer Communications Qin, Zhijin; Ye, Hao; Li, Geoffrey Ye ...
IEEE wireless communications,
2019-April, 2019-4-00, 20190401, Volume:
26, Issue:
2
Journal Article
Peer reviewed
Open access
DL has shown great potential to revolutionize communication systems. This article provides an overview of the recent advancements in DL-based physical layer communications. DL can improve the ...performance of each individual block in communication systems or optimize the whole transmitter/receiver. Therefore, we categorize the applications of DL in physical layer communications into systems with and without block structures. For DL-based communication systems with the block structure, we demonstrate the power of DL in signal compression and signal detection. We also discuss the recent endeavors in developing DL-based end-to-end communication systems. Finally, potential research directions are identified to boost intelligent physical layer communications. Introduction
In ecological analysis, complexity has been regarded as an obstacle to overcome. Here we present a straightforward approach for addressing complexity in dynamic interconnected systems. We show that ...complexity, in the form of multiple interacting components, can actually be an asset for studying natural systems from temporal data. The central idea is that multidimensional time series enable system dynamics to be reconstructed from multiple viewpoints, and these viewpoints can be combined into a single model. We show how our approach, multiview embedding (MVE), can improve forecasts for simulated ecosystems and a mesocosm experiment. By leveraging complexity, MVE is particularly effective for overcoming the limitations of short and noisy time series and should be highly relevant for many areas of science.
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This paper introduces a novel rotation-based framework for arbitrary-oriented text detection in natural scene images. We present the Rotation Region Proposal Networks , which are designed to generate ...inclined proposals with text orientation angle information. The angle information is then adapted for bounding box regression to make the proposals more accurately fit into the text region in terms of the orientation. The Rotation Region-of-Interest pooling layer is proposed to project arbitrary-oriented proposals to a feature map for a text region classifier. The whole framework is built upon a region-proposal-based architecture, which ensures the computational efficiency of the arbitrary-oriented text detection compared with previous text detection systems. We conduct experiments using the rotation-based framework on three real-world scene text detection datasets and demonstrate its superiority in terms of effectiveness and efficiency over previous approaches.
Mesozoic (Triassic–Cretaceous) magmatic rocks and structural deformation are widely distributed in the North China Craton (NCC) and are crucial to understanding the timing, location, and geodynamic ...mechanisms of lithospheric thinning and decratonization of the NCC. Our new geochronological, geochemical and structural data combined with previously published results on Mesozoic magmatic rocks and deformational structures in the NCC indicate a temporal and spatial migration of magmatism and deformation from its margins to its cratonal interior. Triassic and Early Jurassic igneous rocks are only distributed along the northern, southern and eastern margins of the NCC. In contrast, Cretaceous magmatic rocks are widely distributed in whole eastern and central parts of the NCC. There is a younging trend for Mesozoic magmatic rocks from the northern and eastern parts (Yanshan, Jiaodong Peninsula and Liaodong) to the central part of the NCC (Taihangshan). Mesozoic deformation in the NCC exhibits a similar migration trend from craton margins to its inland areas. Triassic–Early Jurassic deformation mainly occurred in the margins of the NCC and transformed from compression during the Early–Middle Triassic to extension during the Late Triassic to Early Jurassic in its northern margin. Middle–Late Jurassic to earliest Cretaceous deformation is widely distributed in the NCC and exhibited non-unique contractional directions usually perpendicular to boundaries of the NCC and its Ordos block, indicating that it was likely controlled by multiple tectonic regimes during the Middle–Late Jurassic to earliest Cretaceous. Early Cretaceous deformation was characterized by near unique NW–SE extension that was likely controlled by unique geodynamic regime that probably related to the far-field effect of Cretaceous Paleo-Pacific plate subduction. The above mentioned temporal and spatial migrations of Mesozoic magmatic rocks and deformation indicate that lithospheric thinning and decratonization of the NCC was diachronous and complex. The lithospheric thinning and decratonization of the NCC initially started from its northern and eastern margins as a result of post-collisional/post-orogenic lithospheric delamination during the Middle–Late Triassic, and then spread to the interior of the craton during the Late Mesozoic. Interactions of the surrounding orogenesis and the small size of the NCC may have played important roles on its Late Mesozoic lithospheric thinning and decratonization.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
7.
Detecting Causality in Complex Ecosystems Sugihara, George; May, Robert; Ye, Hao ...
Science (American Association for the Advancement of Science),
10/2012, Volume:
338, Issue:
6106
Journal Article
Peer reviewed
Identifying causal networks is important for effective policy and management recommendations on climate, epidemiology, financial regulation, and much else. We introduce a method, based on nonlinear ...state space reconstruction, that can distinguish causality from correlation. It extends to nonseparable weakly connected dynamic systems (cases not covered by the current Granger causality paradigm). The approach is illustrated both by simple models (where, in contrast to the real world, we know the underlying equations/relations and so can check the validity of our method) and by application to real ecological systems, including the controversial sardine-anchovy-temperature problem.
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•Ni/mesoporous TiO2 photothermal catalyst was prepared and applied for MDR reaction.•Activities of prepared photothermal catalyst were investigated under different conditions.•Synergistic effect of ...photothermal catalysis could improve the performance of catalyst.•Mechanism of photothermal synergistic effect was discussed based on characterization of catalyst.
Developing new highly efficient catalytic technique is critical for solar photo -thermal -chemical conversion. Among kinds of techniques, photothermal catalysis attracts an increasing attention. In this paper, a Ni/mesoporous TiO2 photothermal catalyst was prepared and applied for methane dry reforming reaction under high temperature environment. Catalytic activities of the prepared catalyst were investigated in a homemade fixed bed photothermal reactor under different temperatures and lighting conditions. And mechanism of photothermal synergistic effect was characterized by using scanning electron microscope (SEM), high resolution transmission electron microscope (HR-TEM), BET, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV–Vis-Nir spectrophotometer and Photoluminescence spectra. The results shown that (1) Catalytic activity of the prepared photothermal catalyst in present work performs better than the public reported catalysts in literatures. (2) Comparisons of light and dark experiments of different catalysts proved that the synergistic effect of photothermal catalysis could significantly improve the formation rates of products, and increase the conversions of reactants. The reason is attributed to the formation of Ni-TiO2 heterogeneous structure, which can broaden the optical response range of incident light, as well as enhance the separation of excited e−/h+ pairs in the semiconductor TiO2. (3) Increasing lighting intensity could enhance the formation rates of CO/H2 correspondingly. (4) Compared to catalytic performances of the catalyst under ultraviolet and visible-near-infrared conditions, full spectrum incident light could improve the formation rates of products under the cooperative effect of different spectrum. The testing results indicate that utilizing photothermal synergistic effects to realize the process intensification is beneficial and instructive for the future solar photo -thermal -chemical conversion.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•Progress of NMR analysis in polysaccharide structure and conformation is summarized.•NMR spectra data of typical polysaccharides are collected.•NMR analysis in cell wall structure in ...situ and other applications are hotspots.•Challenges and perspertives of NMR analysis in polysaccharides are pointed out.
Nuclear magnetic resonance (NMR) has been widely used as an analytical chemistry technique to investigate the molecular structure and conformation of polysaccharides. Combined with 1D spectra, chemical shifts and coupling constants in both homo- and heteronuclear 2D NMR spectra are able to infer the linkage and sequence of sugar residues. Besides, NMR has also been applied in conformation, quantitative analysis, cell wall in situ, degradation, polysaccharide mixture interaction analysis, as well as carbohydrates impurities profiling. This review summarizes the principle and development of NMR in polysaccharides analysis, and provides NMR spectra data collections of some common polysaccharides. It will help to promote the application of NMR in complex polysaccharides of biochemical interest, and provide valuable information on commercial polysaccharide products.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
To improve the efficiency and accuracy of kinematic calibration, the selection of measurement configurations is an important issue. In previous research, optimal measurement configurations mainly are ...selected by maximizing observability indices. However, the traditional observability indices only focus on the identification efficiency of the error parameters, while the purpose of robot kinematic calibration is to improve accuracy. To solve the inconsistency of the purpose between the observability index and calibration, the concept of the residual index to represent the residual distribution of the end effector after robot kinematic calibration with the measurement noise is proposed. Based on the quadratic form minimization of residuals, this article defines a specific residual index,
O
r
, which is dimensionless and strictly better with the increase of measurement configurations. The indices are used to select measurement configurations in the kinematic calibration of a 5-DOF 2UPU/SP-RR hybrid robot, and the calibration results show that the proposed residual index is better than the traditional indices in the accuracy and stability of the end effector residual.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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