Search Results (69)

The Very Long Baseline Interferometry Global Observing System (VGOS), a global network of stations equipped with small-diameter, fast-slewing antennas and broadband receivers, is primarily utilized for geodesy and astrometry. In China, the Shanghai and Urumqi VGOS stations have been developed to perform radio source observation regularly. However, these VGOS stations have not yet been used to observe Earth satellites or deep-space probes. In addition, suitable systems for processing VGOS satellite data are unavailable. In this study, we explored a data processing pipeline and method suitable for VGOS data observed in the dual linear polarization mode and applied to the differential observation of satellites. We present the VGOS observations of the Chang’e 5 lunar orbiter as a pilot experiment for VGOS observations of Earth satellites to verify our processing pipeline. The interferometric fringes were obtained by the cross-correlation of Chang’e 5 lunar orbiter signals. The data analysis yielded a median delay precision of 0.16 ns with 30 s single-channel integration and a baseline closure delay standard deviation of 0.14 ns. The developed data processing pipeline can serve as a foundation for future Earth-orbiting satellite observations, potentially supporting space-tie satellite missions aimed at constructing the terrestrial reference frame (TRF). Full article

The rapid advancement and broad adoption of digital technologies have infused ESG practices with new dimensions and significance. Drawing on panel data from Chinese A-share listed companies spanning from 2012 to 2023, this paper aims to explain the impact of digital transformation on corporate ESG performance, explore its mechanisms and external regulatory effects, and provide systematic ideas and methods for improving corporate ESG performance from the perspective of digital transformation. The key findings of this study are summarized as follows: (1) Digital transformation (DT) has a significant positive effect on corporate ESG performance, and this association remains statistically robust following multiple robustness tests and a correction for potential endogeneity. (2) An analysis of the entire operational process reveals that DT improves ESG performance through enhancing environmental information disclosure quality, strengthening the integration of digital and physical industry technologies, and bolstering supply chain resilience. (3) The implementation of the “Broadband China” strategy exerts a positive moderating effect on the linkage between DT and ESG performance. (4) A heterogeneity analysis shows that the positive impact of DT on ESG performance is more significant and stable in non-state-owned enterprises, eastern regions, less-polluted areas, and growth stage enterprises. These findings offer theoretical and empirical insights for understanding ESG performance drivers. However, the focus on Chinese A-share firms and the use of Sino-Securities ratings may limit generalizability, warranting further improvement. Full article

Improving the efficiency of green development is a crucial step towards achieving the “dual carbon” goal and promoting regional sustainable development. Currently, China has made a decision to foster new quality productive forces, aiming at upgrading traditional productive forces by digitization, which brings new opportunities for urban green transformation. Drawing upon a perspective from new quality productive forces, this paper constructs a framework of impact mechanism about “production factors–productivity–production relations” and uses 108 cities in the Yangtze River Economic Belt to investigate the impact effects, mechanisms, and disparities of the digital economy on urban green development. The research findings indicate the following: (1) The digital economy has a nonlinear influence on green development, with a critical value of 0.149. The conclusion still valid after “Utest” and robustness checks. (2) With the new strategy, digital economy indirectly influences urban green process through nonlinear mediating effects of green technology and green finance, as well as linear mediating effects of resource allocation and industrial structure. (3) There are notable effects heterogeneity across urban agglomerations and individual cities, as well as between resource-based and non-resource-based cities. (4) Furthermore, the policy intensity exerts a stage enhancing effect on the influence. With the promotion of digital policies such as Broadband China, the influence shows a phased increasing trend. The research provides valuable insights for harnessing new quality productive forces to power the digital economy and regional green transformation. Full article

Nowadays, the security and stability of the global industrial chain are facing unprecedented challenges. In this context, understanding how industrial robots affect chain resilience is key to promoting high-quality economic development. This study focuses on 104 cities in the Yangtze River Delta, using data from 2006 to 2021. It applies a threshold regression model and a spatial Durbin model to examine how industrial robot penetration drives chain resilience and how its effects spread across regions. The results reveal three main findings: First, the integration of advanced manufacturing and modern services, together with strong urban innovation capacity, plays a significant role in enhancing industrial chain resilience. Second, this study evaluates policy experiments, such as Low-Carbon City and Broadband China initiatives, using a multi-period difference-in-differences model. The findings show that pilot cities involved in these programs demonstrate higher levels of chain resilience. Third, the relationship between robot penetration and chain resilience shows clear spatial and temporal patterns. Cities with higher robot usage tend to drive development in surrounding areas. This, in turn, encourages more intensive production and fosters stronger coordination across industries. Overall, this study contributes to the growing body of research on chain resilience. More importantly, it offers practical policy insights. Governments and regional firms can work together to build a new development model that enhances resilience and supports long-term economic stability. Full article

Enhancing carbon emission efficiency is crucial for achieving carbon reduction and economic growth. This paper focuses on the digital–financial dual pilot policy formed by the Broadband China strategy pilot (BCP) policy and the Promoting Science and Technology to Combine with Finance pilot (TFCP) policy. Using the panel data of 284 prefecture-level cities in China from 2007 to 2022 and nighttime light data, this paper adopts the super-efficiency SBM model to calculate urban carbon emission efficiency. Based on this efficiency, this paper employs the staggered difference-in-differences model to discuss the impact of the dual pilot policy on urban carbon emission efficiency. The research results indicate that the dual pilot policy significantly improves urban carbon emission efficiency, and compared to the single pilot policy, the dual pilot policy has a greater effect on improving carbon emission efficiency. This conclusion still holds after the parallel trend test, heterogeneous treatment effects test, and other robustness tests. Mechanism analysis demonstrates that the dual pilot policy enhances urban labor, capital, and credit resource allocation efficiency and green technological innovation by generating resource allocation and collaborative innovation effects, thereby improving urban carbon emission efficiency. Further analysis reveals that implementing the TFCP policy first, followed by the BCP policy, can more effectively maximize the dual pilot policy’s positive impact on urban carbon emission efficiency. The impact of the dual pilot policy on urban carbon emission efficiency exhibits heterogeneity, depending on the resource endowment, digital infrastructure level, administrative hierarchy, economic and financial development level, and intellectual property protection intensity of cities. This paper provides valuable insights for effectively implementing the dual pilot policy and achieving a win–win outcome in carbon reduction and economic development. Full article

Against the backdrop of the structural transition in China’s economic landscape, the implementation of digital economy policies—particularly through the Broadband China Demonstration Cities initiatives—has significantly enhanced urban ecological resilience. Based on panel data from 280 prefecture-level cities in China over the period 2013–2022, this study employs the national big data comprehensive pilot zone as a quasi-natural experiment and utilizes the dual machine learning method to examine how pilot zone construction influences urban ecological resilience. This analysis provides theoretical support for fostering green urban development. The results are summarized as follows. (1) The construction of national big data comprehensive pilot zones significantly enhances urban ecological resilience. The conclusion is robust to various tests, including the removal of outliers, changes in sample splitting ratios, and alterations in machine learning algorithms. (2) The construction of national big data comprehensive pilot zones indirectly improves urban ecological resilience through pathways of green innovation and energy efficiency. (3) This study assesses the heterogeneity of policy effects based on the generalized random forest (GRF) model to identify the sources of heterogeneity in policy effects, and conducts a comprehensive heterogeneity analysis from the three dimensions of resource endowments, geographical location characteristics, and the attributes of environmental protection zones. These findings enrich the analysis of the consequences of national big data comprehensive pilot zone policies and offer a theoretical basis and policy reference for how constructing big data pilot zones can better serve urban ecological development. Full article

Urban digital intelligence transformation (DIT) has emerged as a key driver of sustainable development in the era of rapid technological advancement. This study utilized the spatial Durbin model with difference-in-differences (SDM-DID) to explore the intrinsic relationship between DIT and intercity collaborative innovation. The findings indicate that DIT significantly enhances collaborative innovation locally and in other cities. DIT accelerates the movement of R&D talent, capital, and knowledge while driving collaborative innovation across local and neighboring cities by enhancing market potential. Collaborations between enterprises and universities exhibit stronger direct and indirect positive effects, collectively driving the development of sustainable intercity collaborative innovation. Additionally, the study finds that the impact of DIT on substantial innovation is greater than that of non-substantial innovation. Furthermore, the digital transformation of large and central cities has a stronger promotional effect on both local and neighbor collaborative innovation, fostering the sustainable development of intercity innovation cooperation. These results deepen our understanding of the relationship between DIT and intercity collaborative innovation and provide policy insights for enhancing intercity collaboration and promoting regional sustainable development. Full article

China aims for high-quality development by balancing energy use and economic growth, leveraging digital infrastructure to foster a resource-efficient, eco-friendly society and boost economic progress. In this context, by using panel data from 279 Chinese cities spanning 2006–2021, this study employs a multi-phase difference-in-differences (DID) technique to disclose how the Broadband China Pilot Policy (BCPP) affects energy consumption. The results reveal that the BCPP can greatly lower urban energy consumption, which is further validated by robustness tests, including PSM-DID estimation, Bacon decomposition, and placebo testing. Heterogeneity testing shows the BCPP significantly lowers energy consumption in large, eastern, non-resource-based, and high-digital inclusive finance cities compared to smaller, western, resource-based, and low-digital inclusive finance cities. Furthermore, the mechanism analysis indicates that the BCPP contributes to decreased urban energy use by transforming the industrial structure, enhancing financial growth, and improving green technology innovation. To effectively harmonize energy consumption with urban development, it is recommended to accelerate the advancement of digital infrastructure, tailor the industrial structure to meet local needs, and promote greater financial and green innovation development. Full article

A digital infrastructure has the potential to mitigate the digital exclusion in rural areas, offering a pathway to alleviate the financial vulnerability of rural households. This paper investigates the impact of the Broadband China pilot policy—an important government initiative—on rural household financial vulnerability, utilizing data from five waves of the China family panel studies (CFPS) spanning from 2012 to 2020. By leveraging the quasi-natural experiment provided by the Broadband China initiative, this study makes a novel contribution to understanding how a digital infrastructure affects financial sustainability in rural households. The findings show that the Broadband China pilot policy significantly reduces rural household financial vulnerability, with particularly strong effects on female-headed households, spousal-headed households, and those in regions with a limited traditional or advanced digital finance infrastructure. Further analysis reveals that a digital infrastructure enhances rural household financial resilience by increasing land transfer opportunities through an ‘income effect’ and by fostering non-farm employment and financial literacy through a ‘security effect’. This paper contributes to the literature by shedding light on the specific mechanisms through which a digital infrastructure enhances the financial sustainability of rural households and offers valuable insights into policies aimed at bridging the rural–urban divide. Full article

The development of digital infrastructure plays a crucial role in addressing regional disparities, especially in bridging urban–rural gaps. This paper evaluates the impact of the “Broadband China Strategy” (BCS), which exogenously accelerated broadband infrastructure expansion in both urban and rural areas. Using a staggered difference-in-differences (DID) approach, we assess the long-term effects of broadband adoption on labor market outcomes. Our findings show that BCS increased rural wages by 7% to 9%, with no significant impact on urban wages. The wage increase in rural areas is primarily driven by job creation and human capital accumulation, both of which contribute to narrowing the urban–rural wage gap. Additionally, the study uncovers heterogeneity in BCS effects, with stronger impacts observed in underdeveloped regions and among vulnerable groups. These results highlight that targeted digital infrastructure initiatives like BCS can help reduce urban–rural income inequality and promote more inclusive economic growth. Full article

We observed high-quality waves from a repeatable airgun seismic source recorded by a linear ultra-dense seismic array across the Xiliushui fault zone, one of the inactive faults in the Qilian Mountain, on the northeastern margin of the Tibetan Plateau, China. We used Snell’s law of seismic ray propagation to determine a simplified ambient velocity model. Based on the flexible and precise spectral element method, we computed broadband synthetic seismograms for a shallow low-velocity fault zone (FZ) to model the direct P-wave travel time delay and incident angle of the wavefield near the FZ. The FZ extent range and boundaries were inverted by apparent travel time delays and amplification patterns across the fault. According to prior information on the properties of the direct P-waves, we could constrain the inverse modeling and conduct a grid search for the fault parameters. The velocity reduction between the FZ and host rock, along with the dip angle of the FZ, were also constrained by the P-wave travel time delay systematic analysis and incoming angle of the P-waves. We found that the Xiliushui fault has a 70~80 m-wide low-velocity fault damage zone in which the P-wave velocity is reduced to ~40% with respect to the host rock. The fault damage zone dips ~35°southwest and extends to ~165 m in depth. The repeatability and environment protection characteristics of the airgun seismic survey and the economic benefits of a limited number of instruments setting are prominent. Full article

Enhancing urban innovation resilience is crucial for adapting to change and pursuing innovation-driven, high-quality development. The global trend of digital transformation has profound implications for urban innovation; however, the specific effects of digital transformation on urban innovation resilience remain insufficiently explored. This study utilizes panel data from 285 prefecture-level and above cities in China, spanning from 2007 to 2022. It treats the Broadband China Pilot (BCP) policy as a quasi-natural experiment of digital transformation and employs a time-varying Difference-in-Differences (DID) method to investigate the impact of digital transformation on urban innovation resilience. The results yield several important insights: (i) digital transformation enhances urban innovation resilience; (ii) the effect of digital transformation on urban innovation resilience is heterogeneous across regions and city sizes; (iii) digital transformation improves urban innovation resilience through the mediation effect of green total factor productivity (GTFP); (iv) urban industrial upgrading and urban innovation vitality play significant moderating roles in the relationship between digital transformation and urban innovation resilience. These findings contribute to a deeper theoretical understanding of the relationship between digital transformation and urban innovation resilience. Full article

Based on the panel data of 283 prefecture-level cities in China from 2010 to 2021, this paper takes the pilot policy of “Broadband China” as a natural experiment to evaluate the impact of digital infrastructure construction on urban ecological welfare performance and its mechanism by using a progressive difference–difference model. The results show that China’s digital infrastructure construction will significantly reduce the performance of urban ecological welfare. Through the analysis of input and output, it is found that the construction of digital infrastructure can significantly reduce resource consumption and increase welfare output, especially economic welfare, but at the level of environmental pollution, it will significantly increase the discharge of industrial wastewater, which may be the main reason for the negative effect of digital infrastructure construction. Through the group analysis, it is found that the overall negative impact of digital infrastructure construction on ecological welfare performance may be caused by the ecologically fragile western region and the unreasonable industrial structure. Through the adjustment model, it is found that innovation investment can positively regulate the negative impact of digital infrastructure on ecological welfare performance. The grey model (GM) is further used to forecast the data for 2022–2025, and it is found that while the negative impact of digital infrastructure is decreasing, it is still significant. This study provides empirical evidence for accurately understanding the effect and mechanism of digital infrastructure construction on ecological welfare performance. Full article

Solar radio spectral observation is one of the essential approaches for solar physics research, which helps us study the plasma dynamics in the solar atmosphere. The Solar Broadband Radio Dynamic Spectrometer (SBRS) started observing the Sun at Huairou Solar Observing Station in Beijing, China, in 1999. It has obtained a large amount of high-quality observation data of solar radio dynamic spectra in the centimeter–decimeter wavelengths (1.10–7.60 GHz). In particular, the observations with high-temporal resolution of millisecond and high-frequency resolution of MHz display plenty of superfine structures in the dynamic spectrum, which provide crucial information on the radiation process of various radio bursts. We review the past history of solar radio spectral observation and scientific results of SBRS. It is meaningful and will undoubtedly help us inspire new ideas for future research. The understanding of the basic plasma processes in solar plasma could also promote the development of solar physics, astrophysics, and space weather. To broaden the observation frequency range, we propose a new spectrometer at millimeter wavelengths (20–100 GHz) with ultra-wideband and high time–frequency resolution to study the physical processes in the solar transition region. This will open a new window for solar physics research and will provide crucial observational evidence for exploring a series of major issues in solar physics, including coronal heating, solar eruptions, and the origin of solar winds. Full article

To study the dynamic response of multi-span mortise and tenon stone bridges under natural excitation, a bluestone multi-span stone bridge with a main span of 2.56 m in southern China was taken as the research object. Based on the collected pulsating signals of bridge piers and slabs, the natural frequencies and damping ratios of the main span bridge slab and pier were analyzed using the half-power broadband method (HPBM) and random decrement technique (RDT). Modal analysis was conducted using ANSYS, and the results were compared with those obtained from on-site experiments for further performance analysis. The research results of this article indicate that the natural frequency range of the 2.56-m bridge slab identified by measured signals is 48–49 Hz, and the damping ratio range is 33.33–36.61%. The natural frequency of the central pier is 75–76 Hz, and the damping ratio range is 26.39–27.83%. Through finite element modal analysis, the natural frequency of the bridge slab is 54.401 Hz, with an error of 10.5%. The natural frequency of the overall stone bridge is about 82.2 Hz, with an error of about 8.2%. The validated finite element model was subjected to normal water flow impact and erosion simulation. The results indicate that under erosion with fewer particles and lower flow rates, the upstream pier bottom at the center receives the highest relative erosion mass and displacement per unit area. The bridge deck near the main span also experienced relative displacement. Therefore, in the subsequent protection work, special attention should be paid to these components. Full article