125 research outputs found

    Local connectivity of Julia sets for rational maps with Siegel disks

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    We prove that a long iteration of rational maps is expansive near boundaries of bounded type Siegel disks. This leads us to extend Petersen's local connectivity result on the Julia sets of quadratic Siegel polynomials to a general case. A new key feature in the proof is that the puzzles are not used.Comment: 42 pages, 12 figures; The introduction was rewritten and some references were update

    Impact of the digital economy on low carbon sustainability evidence from the Yellow River Basin

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    As the digital economy increasingly dominates a substantial portion of the national economy, comprehending its role in promoting sustainable development has become an imperative research question—particularly in the context of the Yellow River Basin, where there exists an urgent need to shift toward more sustainable modes of economic growth. Utilizing panel data spanning from 1999 to 2020 for 114 cities in the Yellow River Basin, this study develops a comprehensive evaluation framework for sustainable development, incorporating economic, social, and ecological dimensions. The empirical findings reveal that the digital economy acts as a catalyst for sustainable development. Importantly, these results withstand both endogeneity tests and robustness checks. Further heterogeneity analysis indicates that the positive impact of the digital economy on sustainable development is more pronounced in regions directly traversed by the Yellow River and in areas with higher sustainability levels. Moreover, the enactment and implementation of the 13th Five-Year National Information Plan have emphasized the role of the digital economy in enhancing sustainable development. Mechanism tests also illustrate those elevated levels of personal digital acceptance and government intervention contribution to amplify the digital economy’s positive impact on sustainable development. In conclusion, policy recommendations are put forward, including optimizing industrial structure, strengthening data governance and environmental monitoring, promoting innovation-driven development, and fostering collaborative growth

    Femtosecond Pulse Temporal Overlap Estimation and Adjustment in SSFS-Based CARS System

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    This work is licensed under a Creative Commons Attribution 4.0 International License.We present and verify a residual-pump-based temporal overlap estimation method in soliton self-frequency shift-based coherent anti-Stokes Raman scattering system. The residual pump light, output by a highly nonlinear photonic crystal fiber, acts as a crucial link between the pump and Stokes pulses during the temporal overlap estimation. The wavelength-dependent optical delay is estimated to be 0.141 ps/nm when the Stokes wavelength is 900 nm ~1050 nm according to the temporal overlap estimation method. The actual measurement result is 0.138 ps/nm based on the nonresonant signal from a microscope slide, which is very close to the estimated result. In addition, the Raman resonant signals of liquid cyclohexane at 2853 cm -1 , 2923 cm -1 and 2938 cm -1 have also been successfully detected at the predicted optical delays 427.27 ps and 428.17 ps

    The infrared radiation and vacuum assisted drying kinetics of flue-cured tobacco leaf and its drying quality analysis

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    [EN] Dehydration is widely involved in tobacco processing such as tobacco leaf curing, tobacco trip redrying and cut tobacco drying, which plays a key role due to its effect on the physical and chemical quality of tobacco. The current drying methods in tobacco processing mainly use heat conduction, heat convection or their combination to dehydrate tobacco materials. However, radiation heat transfer as one of basic heat transferways has not been investigated in the tobacco drying. In the present work, infrared radiation dryer was designed to explore the tobacco infrared radiation drying characteristics. The effect of radiation heat transfer conditions and vacuum on the drying kinetics and temperature of tobacco leaves was investigated. Diffusion coefficient of middle tobacco leaves C2F is between 0.848×10-10 ~ 1.597×10-10 m2/s. At the same time, the pore structure andpetroleum ether tobacco extracts in dried tobacco were also analyzed in order to explore the different effects of infrared radiation drying and traditional drying technology on tobacco quality.Zhu, W.; Guo, G.; Liu, C.; Cheng, L.; Wang, L. (2018). The infrared radiation and vacuum assisted drying kinetics of flue-cured tobacco leaf and its drying quality analysis. En IDS 2018. 21st International Drying Symposium Proceedings. Editorial Universitat Politècnica de València. 919-925. https://doi.org/10.4995/IDS2018.2018.7612OCS91992

    Miniature viscometer incorporating GaN optical devices with an ultrawide measurement range

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    Exploring the Potential of Gaofen-1/6 for Crop Monitoring: Generating Daily Decametric-Resolution Leaf Area Index Time Series

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    High spatiotemporal resolution time series of leaf area index (LAI) are essential for monitoring crop dynamics and validating coarse-resolution LAI products. The optical satellite sensors at decametric resolution have historically suffered from a long revisit cycle and cloud contamination issues that hampered the acquisition of frequent and high-quality observations. The 16-m/four-day resolution of the new-generation Gaofen-1 (GF-1) and Gaofen-6 (GF-6) satellites provide an unprecedented opportunity to address these limitations. Here, we developed an effective strategy to generate daily 16-m LAI maps combining GF-1/6 data and ground LAINet measurements. All high-quality GF-1/6 observations were utilized first to derive smoothed time series of vegetation indices (VIs). Second, a random forest regression (RF-r) model was trained to link the VIs with corresponding field LAI measurements. The trained RF-r was finally employed to generate the LAI maps. Results demonstrated the reliability of the reconstructed daily VIs (relative error (RE) < 1%) and the derived LAI time series, which greatly benefited from GF-1/6 high-frequency observations. The direct comparison with field LAI measurements by LAI-2200/LI-3000 showed the good performance of retrieved LAI maps, with bias, root mean square error (RMSE), and R2 of 0.05, 0.59, and 0.75, respectively. The LAI time series well captured the spatiotemporal variation of crop growth. Furthermore, the continuous GF-1/6 LAI maps outperformed Sentinel-2 LAI estimates both in terms of temporal frequency and accuracy. Our study indicates the potential of GF-1/6 to generate continuous decametric-resolution LAI maps for fine-scale agricultural monitoring

    Water quality variation in the middle route of South-to-North Water Diversion Project, China

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    The South-to-North Water Division Middle Route Project (MRP) is currently the longest inter-basin water diversion project in the world. It benefits a large population and its water quality has attracted much attention. In this study, seasonal investigations on 11 sampling sites along the MRP were conducted from 2018 to 2019; water temperature, pH, turbidity, transparency, CODMn, dissolved oxygen, total phosphorus, phosphate, total nitrogen, ammonia, nitrate, and chlorophyll a were determined synchronously. Single leakage distance clustering analysis identified the spatio-seasonal heterogeneity of physiochemical parameters. The trophic level index (TLI) and the water quality status were assessed: TLI increased and WQI decreased from south to north; TLI and WQI had seasonal differences (p &lt; 0.001), the best water quality was observed in autumn, and the lowest TLI was observed in winter. The trophic level was “oligotrophic to mesotrophic”; water quality status was “good.” The multiple linear stepwise regression analysis confirmed that total nitrogen (TN), Chl a, and CODMn were the driving factors in water quality. These factors were applied to build the simplified WQI model, which was confirmed as a reliable method of water quality assessment for the MRP and a fitting substitute for TLI and WQI. The results provided support for the water quality evaluation of the MRP
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