The non-archimedean SYZ fibration

We construct non-archimedean SYZ fibrations for maximally degenerate Calabi-Yau varieties, and we show that they are affinoid torus fibrations away from a codimension two subset of the base. This confirms a prediction by Kontsevich and Soibelman. We also give an explicit description of the induced integral affine structure on the base of the SYZ fibration. Our main technical tool is a study of the structure of minimal dlt-models along one-dimensional strata.Comment: Final version, to appear in Compositio Mathematic

Multi-epoch analysis of the X-ray spectrum of the active galactic nucleus in NGC 5506

We present a multi-epoch X-ray spectroscopy analysis of the nearby narrow-line Seyfert I galaxy NGC 5506. For the first time, spectra taken by Chandra, XMM-Newton, Suzaku, and NuSTAR - covering the 2000-2014 time span - are analyzed simultaneously, using state-of-the-art models to describe reprocessing of the primary continuum by optical thick matter in the AGN environment. The main goal of our study is determining the spin of the supermassive black hole (SMBH). The nuclear X-ray spectrum is photoelectrically absorbed by matter with column density $\simeq 3 \times 10^{22}$ cm$^{-2}$. A soft excess is present at energies lower than the photoelectric cut-off. Both photo-ionized and collisionally ionized components are required to fit it. This component is constant over the time-scales probed by our data. The spectrum at energies higher than 2 keV is variable. We propose that its evolution could be driven by flux-dependent changes in the geometry of the innermost regions of the accretion disk. The black hole spin in NGC 5506 is constrained to be 0.93$\pm _{ 0.04 }^{0.04}$ at 90% confidence level for one interesting parameter.Comment: 13 pages, 9 figures. v2: refereed versio

Can regional integration narrow city-level energy efficiency gap in China?

Improving energy efficiency is essential for energy conservation, emissions reduction, and sustainable development. Prevalent huge efficiency gaps are not advantageous for the improvement of the region's overall energy efficiency. Although studies have analyzed the influencing factors of the regional energy efficiency gap, the impact of regional integration on the regional energy efficiency gap remains untested. This paper applies the extended stochastic frontier analysis (SFA) method that incorporates time-varying, time-invariant and city heterogeneous characteristics to estimate the city-level energy efficiency in China from 2005 to 2017. Building on the “center-periphery” framework, we further calculate the regional energy efficiency gap and investigate the impact of regional integration on the regional energy efficiency gap through the generalized moment method (GMM). The results show that 1) average city-level energy efficiency is 44.2%, ranging from 2.9% to 75.5%, indicating that China has a huge regional energy efficiency gap; 2) there is a U-shaped relationship between regional integration and the regional energy efficiency gap within city agglomeration. Improvement in regional integration can narrow the regional energy efficiency gap when the degree of regional integration is low, and expand the efficiency gap when regional integration level is high; 3) government intervention will smooth the impact of regional integration on the regional energy efficiency gap within city agglomeration. Practicable policies to mitigate the regional energy efficiency gap in China are suggested and applicable to other emerging economies, especially for those with a huge imbalance in regional energy efficiency

Peaks of transportation CO2 emissions of 119 countries for sustainable development: Results from carbon Kuznets curve

Transportation has significantly boomed energy consumption and carbon dioxide (CO2) emissions. Understanding and forecasting the dynamic statuses of transportation CO2 emissions is a necessary step before making strategies to decrease CO2 emissions. Carbon Kuznets curve (CKC) hypothesis has been frequently validated properly to present the changing statuses of CO2 emissions in the literature. This study tests the CKC hypothesis using the data recording the CO2 emissions of transportation sectors of 119 countries over the period of 1995–2014, then turning points (TPs) are calculated for the countries where CKC hypothesis is turned out supported. Based on the CKC models, this study identifies different types of TPs, i.e. TP of carbon intensity (TPCI), TP of per capita CO2 emissions (TPPC), and TP of total CO2 emissions (TPTC) of the countries whose data support the CKC hypothesis. According to the earliness of the turning years (TYs) (TYCI, TYPC and TYTC) – the years when CO2 emissions peak – of individual countries, this study identified a step‐wise decoupling strategy for different countries, i.e. (1) first to reach the TPCI, (2) then to reach the TPPC, and (3) finally to reach the TPTC. As a result, the CKC hypothesis was supported by the data of 58 countries, among which, there are still seven countries having not reached any of the three TPs, 23 countries have reached the first‐step TP (TPCI), 9 countries have reached the second‐step TP (TPPC), and 19 countries have reached the third‐step TP (TPTC).Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/156198/2/sd2008.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156198/1/sd2008_am.pd

First Detailed Analysis of a Relatively Deep, Low Mass-ratio Contact Binary: ATO J108.6991+27.8306

We present the first detailed photometric analysis of ATO J108.6991+27.8306 (hereinafter as J108). The short-period close binary J108 was observed by the Nanshan 1 m Wide Field Telescope of the Xinjiang Astronomical Observatory. The obtained BVRI-band light curves were used to determine the photometric solution by using the 2003 version of the Wilson-Devinney code. J108 is a typical deep ( f > 50%), low mass ratio (q < 0.25) overcontact binary system with a mass ratio of q = 0.1501 and a fill-out factor of f = 50.1 %, suggesting that it is in the late evolutionary stage of contact binary systems. We found the target to be a W-type W UMa binary and provided evidence for the presence of starspots on both components. From the temperature-luminosity diagram, the main component is the evolved main sequence star with an evolutionary age of about 7.94 Gyr.Comment: 7 pages, 6 figure

A Clustering-guided Contrastive Fusion for Multi-view Representation Learning

The past two decades have seen increasingly rapid advances in the field of multi-view representation learning due to it extracting useful information from diverse domains to facilitate the development of multi-view applications. However, the community faces two challenges: i) how to learn robust representations from a large amount of unlabeled data to against noise or incomplete views setting, and ii) how to balance view consistency and complementary for various downstream tasks. To this end, we utilize a deep fusion network to fuse view-specific representations into the view-common representation, extracting high-level semantics for obtaining robust representation. In addition, we employ a clustering task to guide the fusion network to prevent it from leading to trivial solutions. For balancing consistency and complementary, then, we design an asymmetrical contrastive strategy that aligns the view-common representation and each view-specific representation. These modules are incorporated into a unified method known as CLustering-guided cOntrastiVE fusioN (CLOVEN). We quantitatively and qualitatively evaluate the proposed method on five datasets, demonstrating that CLOVEN outperforms 11 competitive multi-view learning methods in clustering and classification. In the incomplete view scenario, our proposed method resists noise interference better than those of our competitors. Furthermore, the visualization analysis shows that CLOVEN can preserve the intrinsic structure of view-specific representation while also improving the compactness of view-commom representation. Our source code will be available soon at https://github.com/guanzhou-ke/cloven.Comment: 13 pages, 9 figure