Search

Atmospheric delay is a critical factor affecting high-precision navigation and GNSS water vapor inversion. The terrain in northwest China is highly variable, and the current zenith total delay ( ZTD) model in this region does not adequately consider elevation, which cannot meet the real-time high-precision positioning needs. Therefore, it is urgently necessary to establish a high precision ZTD model for northwest China. The ERA5 data from the European Centre for Medium-Range Weather Forecasts (ECMWF) for 2015—2017 was used to establish a ZTD model (MZTD model) for northwest China that considers non-linear elevation correction. This model addressed the problems of current ZTD models in northwest China, such as neglecting non-linear elevation correction and seasonal variations. The 2018 ERA5 data not involved in the modeling and the 84 GNSS stations data from the Northwest China land state network were jointly used to verify the accuracy and applicability of the MZTD model and to compare the accuracy with the GPT3 model, which was widely used today. The MZTD model's accuracy was compared with the widely used GPT3 model. The results show that, with 2018 ERA5 data and northwest China land network station data as reference values, the root mean square error (RMS) of the MZTD model is 3. 14 cm and 2. 81 cm, respectively, which is about 16. 3% and 21. 7% higher in accuracy than the GPT3 model. Moreover, the MZTD model has fewer model parameters, improving computational efficiency. Therefore, the MZTD model that considers non-linear elevation correction demonstrates better accuracy and applicability in the northwest China region, providing important references for real-time GNSS water vapor detection and navigation positioning in this area. [ABSTRACT FROM AUTHOR]

Copyright of Inorganic Chemicals Industry is the property of Editorial Office of Inorganic Chemicals Industry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Mechanical & Electronic Control Engineering is the property of Omniscient Pte. Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Nuclear Safety is the property of Nuclear & Radiation Safety Center and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Educational activities have obvious influence on the development of social space, which has always been an important topic of theoretical and practical research. In China, with urban economic development and social transformation, the differentiation of residential space caused by differentiation of educational resources is becoming more pronounced. School-district communities in many central cities, especially the high-quality school-district communities in old urban areas, with a strong contrast between high housing price and dilapidated material landscape, high-quality education and poor living environment, have a strong pulling and tearing effect on the value orientation and social practice of individuals, families, and communities. This has become one of the most typical spaces of social-spatial contradiction and distortion. This study introduces the concept of "alienation" (a philosophical term) and investigates the social-spatial characteristics and mechanism of highquality school-district communities, from the theoretical viewpoint of "social-spatial dialectical unity." Taking Nanjing as an example, a survey reveals that a large proportion of the high-quality school-district community is old and dilapidated. Hence, the contrast between their material space and social value is significant, the housing price is at an irrational premium, the educational function surpasses the residential function and becomes the primary function of the community, and residents construct a non-geographical social network and shape an education community neighborhood. The high-quality school-district community in Nanjing exhibits the characteristics of social-spatial alienation, which is common and significant. This study further analyzes the mechanism of alienation, which is logically related to external factors such as housing market reform, school district, and oriental culture. However, in essence, the social-spatial alienation is the result of the impact on the dialectical unity of society and space, displaying the tendency of separation and opposition, which promotes the self-denial and role evolution of the community of "high-quality school-district housing". The social-spatial alienation will lead to many negative effects. It will lay siege to the school district and aggravate the antagonistic effect of society and space. It will trigger the solidification and intergenerational transmission mechanism of social stratification and residential differentiation, leading to the residential re-differentiation. It will encounter such difficulties as the absence of subjects, the misplacement of objectives and the rupture of the mechanism, resulting in the "failure" of school-district community governance. It will highlight the contradictions such as high renewal cost, diversified and complex stakeholders, and resistance to school-district rezoning, and delay the process of renewal of the old city. Based on the philosophical construction of "alienation", the social space characteristics of high-quality school-district community are summarized, which provides a new perspective for the study of urban social space. This study also systematically analyzes and explains the mechanism of socialspatial alienation in high-quality school-district communities, and provides tools for the problems in the transformation and reconstruction of urban social space in China. [ABSTRACT FROM AUTHOR]

Copyright of Applied Mathematics & Mechanics (1000-0887) is the property of Applied Mathematics & Mechanics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)