Search Results (7)

A stable microwave signal transmission system for a distributed system that is capable of simultaneous downloads at multiple arbitrary nodes within the optical path is proposed. The download module, which is based on optical circulators and optical couplers, can be inserted at any node position within the transmission optical path to complete the downloading of frequency-synchronization signals. Experimentally, a distributed frequency-synchronization system with multiple download nodes is demonstrated over 40 km of optical fiber. Experimental results show that the signal has been downlink-transferred from different download modules with the standard deviation of phase jitter being 1°@10 GHz at 1 h through 40-km optical fiber. Moreover, the standard deviation of phase jitter between downloaded signals from any two download modules is also better than 1°@10 GHz at 1 h. In addition, the Allan Deviation is better than ${10}^{-12}$@1 h for the download module. Full article

Ice accumulation on cold surfaces presents significant operational and safety challenges in various fields such as power transmission, aviation, and polar marine transportation. This study investigates the effectiveness of selectively applied superhydrophobic patterns on hydrophilic substrates to locally control freezing behaviors. The freezing dynamics of water droplets impacting surfaces with hybrid wettability patterns were investigated experimentally under cold conditions. The results demonstrate that superhydrophobic surfaces significantly reduce the freezing rate due to decreased contact time and the contact region. By selectively placing superhydrophobic patterns on hydrophilic surfaces, the location of ice formation could be effectively manipulated. The use of multiple superhydrophobic stripes was found to segment the impacting droplets into several parts, implying the ability to selectively avoid ice accumulation at specific areas. Furthermore, experiments identified critical temperature thresholds at which the effectiveness of superhydrophobic stripes diminishes. When the temperature of the substrate is higher than −25 °C, the superhydrophobic stripes can sufficiently divide an impacting droplet leaving no ice at the superhydrophobic region. In the tested temperature range between −25 °C and −40 °C, the ice coverage ratio at the superhydrophobic region increases as temperature decreases, with a maximum value of 25.6 ± 2.33% at −40 °C. Superhydrophobic patterns also exhibited improved deicing efficiency during melting processes, highlighting their potential for robust ice management applications. Full article

In this study, a kilowatt-level high-efficiency narrow-linewidth all-fiber Tm³⁺-doped continuous-wave laser operating at 1.95 μm is demonstrated. Benefitting from an advanced boost design of a two-stage main amplifier, it not only effectively manages heat dissipation resulting from the high pump-induced quantum defect but also realizes the controlled extraction of optical gain and improves the optical conversion efficiency. Finally, this laser system has realized an output power of 1018 W, a linewidth of 3.8 GHz, and a slope efficiency of 60.0% simultaneously. Moreover, a high optical signal-to-noise ratio of over 45 dB and excellent beam quality of M² factors 1.19 are obtained. To the best of our knowledge, this represents the narrowest linewidth and highest slope efficiency achieved in a kilowatt-level Tm³⁺-doped fiber laser. Such a high-performance laser is ideally suited for mid-infrared generation and remote sensing applications. Full article

Investigations of the geochemical compositions of geothermal water, as well as their movements and geneses, are of great significance for the exploration and exploitation of hydrothermal resources. In Zhongshan City, a southern city in Guangdong Province, large amounts of geothermal heat have been discovered. The results of investigations show that the hydrochemical types of geothermal water in the study area are Cl-Na·Ca and Cl-Na. H-O isotopes are basically near the atmospheric precipitation line, and the calculated recharge elevation of geothermal water ranges from 716 to 822 m, which is close to the altitude of the North Peak Mountain in Taishan City. The deep thermal storage temperature ranges from 95.32 to 149.71 °C, and the depth of the thermal cycle ranges from 2638.57 m to 4581.07 m. The genetic model of the geothermal water in this area is that, at favorable structural positions with satisfied water storage conditions, the mixture of atmospheric precipitation and seawater that circulates deep in Earth is heated by terrestrial heat flow under actions such as deep heat exchange and water–rock reactions to leach the salt, finally forming the highly mineralized geothermal water that uplifts out of the surface along faults and crops. The formation of the genetic model of geothermal water will provide a geological basis and technical support for the efficient development and utilization of geothermal resources in Zhongshan City and the coastal area of Southeast China. Full article

Focusing on the water conservation of China’s urban agglomerations (UAs), panel data covering 92 cities in the top five agglomerations from 2006 to 2020 are used to study the relationship between the spatial structure of UAs and the water ecological footprint (WEF) of their cities. WEFs and spatial structures are measured by the ecological footprint models and the rank-size law, respectively. Furthermore, the effects of spatial structure on WEF are estimated through the fixed-effects (FE) model with instrumental variables (IVs). Results suggest that the concentricity of the spatial structure has a nonlinear impact on the WEF, in that as the spatial structure moves away from polycentricity, the WEF first declines and then rises. By reducing the WEF through concentrated development, cities with a large proportion of production WEF or a large population can enjoy more benefits. Therefore, promoting the balanced development of JJJ and PRD and enhancing the role of the growth pole in CY and YRMR can help the water conservation of most cities. Moreover, considering household water use and small-population cities in other water-saving policies can serve as a policy reference in the future. Full article

The optimal allocation of land use is a promising approach to achieving the sustainable use of land resources, to weigh ecological protection and economic development. The urban agglomeration around Poyang Lake is a crucial plate for implementing the spatial planning policy of the national urban agglomeration and supporting the development of the Yangtze River Economic Belt. Based on the ecosystem service value (ESV), we utilize the minimum cumulative resistance (MCR), the gray multi-objective planning (GMOP) and the future land-use simulation (FLUS) model to optimize the quantitative structure and spatial pattern of the land use in 2030. The present study designs four scenarios of baseline development (BD), ecological conservation (EC), economic priority (EP) and coordinated development (CD) to discuss how to optimize land-use allocation while considering ecological security and economic development. The result suggests that the land-use structure and spatial layout in the CD_scenario are relatively reasonable, and the overall eco-economic benefits and landscape pattern levels are better than those of the other three scenarios. Additionally, the ecological security and landscape pattern indices are optimized, landscape fragmentation decreases and aggregation degree increases. This study is instructive to promote the sustainable development of urban agglomeration and land spatial planning. Full article

Exposure to endogenous sex hormones has been reported as a risk factor for breast cancer. The CYP11A1 gene encodes the key enzyme that catalyzes the initial and rate-limiting step in steroid hormone synthesis. In this study, the associations between single nucleotide polymorphisms (SNPs) in CYP11A1 and breast cancer susceptibility were examined. Six SNPs in CYP11A1 were genotyped using the MassARRAY IPLEX platform in 530 breast cancer patients and 546 healthy controls. Association analyses based on a χ² test and binary logistic regression were performed to determine the odds ratio (OR) and 95% confidence interval (95% CI) for each SNP. Two loci (rs2959008 and rs2279357) showed evidence of associations with breast cancer risk. The variant genotype C/T-C/C of rs2959008 was significantly associated with a decreased risk (age-adjusted OR, 0.75; 95% CI, 0.58–0.96; P = 0.023) compared with the wild-type TT. However, the homozygous TT variant of rs2279357 exhibited increased susceptibility to breast cancer (age-adjusted OR, 1.44; 95% CI, 1.05–1.98; P = 0.022). The locus rs2959003 also showed an appreciable effect, but no associations were observed for three other SNPs. Our results suggest that polymorphisms of CYP11A1 are related to breast cancer susceptibility in Han Chinese women of South China. Full article