49 research outputs found

    Linear quadratic mean-field game-team analysis: a mixed coalition approach

    Full text link
    Mean-field theory has been extensively explored in decision analysis of {large-scale} (LS) systems but traditionally in ``pure" cooperative or competitive settings. This leads to the so-called mean-field game (MG) or mean-field team (MT). This paper introduces a new class of LS systems with cooperative inner layer and competitive outer layer, so a ``mixed" mean-field analysis is proposed for distributed game-team strategy. A novel asymptotic mixed-equilibrium-optima is also proposed and verified

    A Unified Relation Analysis of Linear-quadratic Mean-field Game, Team and Control

    Full text link
    This paper revisits well-studied dynamic decisions of weakly coupled large-population (LP) systems. Specifically, three types of LP decision problems: mean-field game (MG), mean-field team (MT), and mean-field-type control (MC), are completely analyzed in a general stochastic linear-quadratic setting with controlled-diffusion in state dynamics and indefinite weight in cost functional. More importantly, interrelations among MG, MT and MC are systematically discussed; some relevant interesting findings are reported that may be applied to a structural analysis of general LP decisions

    Spatiotemporal analysis of vegetation variability and its relationship with climate change in China

    Get PDF
    This paper investigated spatiotemporal dynamic pattern of vegetation, climate factor, and their complex relationships from seasonal to inter-annual scale in China during the period 1982–1998 through wavelet transform method based on GIMMS data-sets. First, most vegetation canopies demonstrated obvious seasonality, increasing with latitudinal gradient. Second, obvious dynamic trends were observed in both vegetation and climate change, especially the positive trends. Over 70% areas were observed with obvious vegetation greening up, with vegetation degradation principally in the Pearl River Delta, Yangtze River Delta, and desert. Overall warming trend was observed across the whole country (\u3e98% area), stronger in Northern China. Although over half of area (58.2%) obtained increasing rainfall trend, around a quarter of area (24.5%), especially the Central China and most northern portion of China, exhibited significantly negative rainfall trend. Third, significantly positive normalized difference vegetation index (NDVI)–climate relationship was generally observed on the de-noised time series in most vegetated regions, corresponding to their synchronous stronger seasonal pattern. Finally, at inter-annual level, the NDVI–climate relationship differed with climatic regions and their long-term trends: in humid regions, positive coefficients were observed except in regions with vegetation degradation; in arid, semiarid, and semihumid regions, positive relationships would be examined on the condition that increasing rainfall could compensate the increasing water requirement along with increasing temperature. This study provided valuable insights into the long-term vegetation–climate relationship in China with consideration of their spatiotemporal variability and overall trend in the global change process

    Automated cropping intensity extraction from isolines of wavelet spectra

    Get PDF
    Timely and accurate monitoring of cropping intensity (CI) is essential to help us understand changes in food production. This paper aims to develop an automatic Cropping Intensity extraction method based on the Isolines of Wavelet Spectra (CIIWS) with consideration of intra- class variability. The CIIWS method involves the following procedures: (1) characterizing vegetation dynamics from time–frequency dimensions through a continuous wavelet transform performed on vegetation index temporal profiles; (2) deriving three main features, the skeleton width, maximum number of strong brightness centers and the intersection of their scale intervals, through computing a series of wavelet isolines from the wavelet spectra; and (3) developing an automatic cropping intensity classifier based on these three features. The proposed CIIWS method improves the understanding in the spectral–temporal properties of vegetation dynamic processes. To test its efficiency, the CIIWS method is applied to China’s Henan province using 250 m 8 days composite Moderate Resolution Imaging Spectroradiometer (MODIS) Enhanced Vegetation Index (EVI) time series datasets. An overall accuracy of 88.9% is achieved when compared with in-situ observation data. The mapping result is also evaluated with 30 m Chinese Environmental Disaster Reduction Satellite (HJ-1)-derived data and an overall accuracy of 86.7% is obtained. At county level, the MODIS-derived sown areas and agricultural statistical data are well correlated (r2 = 0.85). The merit and uniqueness of the CIIWS method is the ability to cope with the complex intra-class variability through continuous wavelet transform and efficient feature extraction based on wavelet isolines. As an objective and meaningful algorithm, it guarantees easy applications and greatly contributes to satellite observations of vegetation dynamics and food security efforts

    Maps of cropping patterns in China during 2015–2021

    Get PDF
    Multiple cropping is a widespread approach for intensifying crop production through rotations of diverse crops. Maps of cropping intensity with crop descriptions are important for supporting sustainable agricultural management. As the most populated country, China ranked first in global cereal production and the percentages of multiple-cropped land are twice of the global average. However, there are no reliable updated national-scale maps of cropping patterns in China. Here we present the first recent annual 500-m MODIS-based national maps of multiple cropping systems in China using phenologybased mapping algorithms with pixel purity-based thresholds, which provide information on cropping intensity with descriptions of three staple crops (maize, paddy rice, and wheat). The produced cropping patterns maps achieved an overall accuracy of 89% based on ground truth data, and a good agreement with the statistical data (R2 ≥ 0.89). The China Cropping Pattern maps (ChinaCP) are available for public download online. Cropping patterns maps in China and other countries with finer resolutions can be produced based on Sentinel-2 Multispectral Instrument (MSI) images using the shared code

    From cropland to cropped field: A robust algorithm for national-scale mapping by fusing time series of Sentinel-1 and Sentinel-2

    Get PDF
    Detailed and updated maps of actively cropped fields on a national scale are vital for global food security. Unfortunately, this information is not provided in existing land cover datasets, especially lacking in smallholder farmer systems. Mapping national-scale cropped fields remains challenging due to the spectral confusion with abandoned vegetated land, and their high heterogeneity over large areas. This study proposed a large-area mapping framework for automatically identifying actively cropped fields by fusing Vegetation-Soil-Pigment indices and Synthetic-aperture radar (SAR) time-series images (VSPS). Three temporal indicators were proposed and highlighted cropped fields by consistently higher values due to cropping activities. The proposed VSPS algorithm was exploited for national-scale mapping in China without regional adjustments using Sentinel-2 and Sentinel-1 images. Agriculture in China illustrated great heterogeneity and has experienced tremendous changes such as non-grain orientation and cropland abandonment. Yet, little is known about the locations and extents of cropped fields cultivated with field crops on a national scale. Here, we produced the first national-scale 20 m updated map of cropped and fallow/abandoned land in China and found that 77 % of national cropland (151.23 million hectares) was actively cropped in 2020. We found that fallow/abandoned cropland in mountainous and hilly regions were far more than we expected, which was significantly underestimated by the commonly applied VImax-based approach based on the MODIS images. The VSPS method illustrates robust generalization capabilities, which obtained an overall accuracy of 94 % based on 4,934 widely spread reference sites. The proposed mapping framework is capable of detecting cropped fields with a full consideration of a high diversity of cropping systems and complexity of fallow/abandoned cropland. The processing codes on Google Earth Engine were provided and hoped to stimulate operational agricultural mapping on cropped fields with finer resolution from the national to the global scale

    Boosting Heterosubtypic Neutralization Antibodies in Recipients of 2009 Pandemic H1N1 Influenza Vaccine

    Get PDF
    Our data demonstrated that the inoculation with vaccine derived from the 2009 pandemic influenza raised vigorous neutralization antibodies against both cognate H1N1 and heterotypic influenza viruses. This observation has important implication for vaccine development

    Toll‐like receptor‐mediated IRE1α activation as a therapeutic target for inflammatory arthritis

    Full text link
    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/102185/1/embj2013183-sup-0004-SourceData-S4.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/102185/2/embj2013183-sup-0001.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/102185/3/embj2013183-sup-0008-SourceData-S8.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/102185/4/embj2013183-sup-0005-SourceData-S5.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/102185/5/embj2013183-sup-0001-SourceData-S1.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/102185/6/embj2013183-sup-0009-SourceData-S9.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/102185/7/embj2013183-sup-0006-SourceData-S6.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/102185/8/embj2013183-sup-0002-SourceData-S2.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/102185/9/embj2013183-sup-0010-SourceData-S10.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/102185/10/embj2013183-sup-0007-SourceData-S7.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/102185/11/embj2013183-sup-0003-SourceData-S3.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/102185/12/embj2013183.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/102185/13/embj2013183.reviewer_comments.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/102185/14/embj2013183-sup-0011-SourceData-S11.pd
    corecore