作者机构:
[Xu, Huimin] Wuhan Polytech Univ, Sch Econ, Wuhan 430048, Peoples R China.;[Xu, Huimin; Hu, Shougeng] China Univ Geosci, Sch Publ Adm, Wuhan 430074, Peoples R China.;[Li, Xi] Wuhan Univ, State Key Lab Informat Engn Surveying Mapping & Re, Wuhan 430079, Peoples R China.
通讯机构:
[Huimin Xu] S;School of Economics, Wuhan Polytechnic University, Wuhan 430048, China<&wdkj&>School of Public Administration, China University of Geosciences, Wuhan 430074, China
关键词:
Yangtze River Economic Belt;urban development;urban area;night-time light;VIIRS
摘要:
Research on urban development patterns and urban sprawl in the Yangtze River Economic Belt (YREB) has received wide attention. However, existing research has always made use of statistical data, which are not often available. Considering the high availability of satellite data, this study attempts to combine two satellite-acquired indexes, including urban area and night-time light, to evaluate the urban development of the YREB during 2012–2019. The methods included using growth index, rank-size law, and the Markov transition matrix, as well as constructing urban night-time light density and unbalanced index of night-time light, derived from the Gini Index. Some important patterns were revealed. Firstly, the three reaches (Upper Reaches, Middle Reaches, and Lower Reaches) in the YREB have all shown rapid growth in urban area and night-time light, and they all have increased in urban density. Secondly, from the perspective of regional disparity, the Upper Reaches have the highest growth rate of the urban area, while the Middle Reaches have the highest growth rate of night-time light; and the Upper Reaches have more urban sprawl, while the Middle Reaches have shown more compact growth. Thirdly, higher urban density is related to more balanced development across cities. Our study suggests new knowledge can be obtained by combining the two indexes for understanding urban development in the YREB.
摘要:
With the cyclical development of emerging technologies, in reality, the evolution dynamics of their innovation networks will inevitably show obvious time attributes. Numerous network analyses of real complex systems usually focus on static networks; however, it is difficult to describe that most real networks undergo topological evolutions over time. Temporal networks, which incorporate time attributes into traditional static network models, can more accurately depict the temporal features of network evolution. Here, we introduced the time attribute of the life cycle of emerging technology into the evolution dynamics of its innovation network, constructed an emerging technology temporal innovation network from a temporal network perspective, and established its evolution model in combination with the life cycle and key attributes of emerging technology. Based on this model, we took 5G technology as an example to conduct network evolution simulation, verified the rationality of the above model building, and analyzed the cyclical evolution dynamics of this network in various topological structures. The results show that the life cycle of emerging technology, as well as multiple knowledge attributes based on the key attributes of emerging technology, are important factors that affect network evolution by acting on node behaviors. Within this study, we provide a more realistic framework to describe the internal mechanism of the cyclical evolution of emerging technology innovation network, which can extend the research on innovation network evolution from the single topological dynamics to the topological–temporal dynamics containing time attributes and enrich the research dimensions of innovation network evolution from the perspective of temporal evolution.
摘要:
This research analyses the relative efficacy of gold price, financial market, and stock exchange hedging against sectoral and industry-level global stock market returns. Incorporating Gold into equity-based asset allocation techniques and assessing the stock market and financial sector during the COVID-19 epidemic is one way to diversify your portfolio and reduce risk. After orthogonalizing raw returns concerning a robust collection of relevant universal variables, we conduct our analysis inside a bivariate GARCH(p, q) framework. To further assess ideal portfolio proportions and the efficacy of hedging methods, we expand the volatility spillovers study by calculating the optimal weights for a minimal risk portfolio and determining the hedge ratio. In high-volatility environments, our results show which financial market and stock exchange sectors and industries investors should prioritize to minimize the risk and maximize reward. Use of country-specific macroeconomic variables indices to supplement the worldwide index, (3) separate analysis for the COVID-19 first wave due to the existing argument that the pandemic raises unexpected market events and our early data showing co-movement among the three unpredictability metrics during the pandemic. These findings have important implications for portfolio entrepreneurs and business investors looking to buy international equities.
摘要:
eBay’s feedback rating system is currently widely used. In this study, we examine if eBay’s feedback rating types (+, 0, −) are consistent with the sentiments reflected in the textual comments posted by buyers. Using the datasets collected from eBay, we test the hypotheses associated with the research questions at three levels: individual, group, and total. Overall, the types of feedback ratings are consistent with the sentiments embedded in the textual comments. However, there are some issues with eBay’s current feedback rating system: (1) at the individual level, the correlation coefficient between the ratings and the comments’ sentiments is low at 0.4311 (<0.5). While the three types of ratings are symmetric, like (−1, 0, +1), buyers’ textual comments have asymmetric distributions of sentiments among these three types. The three simple feedback ratings (+, 0, −) are not fully aligned with the sentiments revealed in the textual comments posted by buyers. We propose expanding the current three ratings into five ratings such as (−2, −1, 0, +1, +2), which might help remedy the issue. We contribute to the literature by tapping into this less-studied area vital to improving the online marketplace’s efficiency.
摘要:
Abstract: Research and development (R&D) investment is very important for firms to gain competitive advantages and sustainable development. Due to the uncertainty of the market and competitors, R&D investment is usually costly and high risk. In such circumstances, firms not only have to figure out the optimal investment timing, but also consider whether to cooperate with competitors to share the risks and costs. In this paper, a two-stage dynamic exchange option game model is proposed for two symmetric competing firms to analyze their R&D investment decision and cooperation. The results show that under uncertainty, the R&D investment timing and cooperation strategy of the two firms depend on the market fluctuation, R&D cost, opportunity benefit of free riding, and the externality of cooperation. If the opportunity benefit of free riding is less than or equal to half of the cooperative research cost, the two firms will invest as early as possible and cooperate. The technology spillover and profits of new products will positively affect the willingness of the competing firms to invest and cooperate in R&D. Moreover, we also calculate the market value thresholds of the investment strategies for the two firms. When the market value is small, the two firms wait for the R&D investment; when the value increases, the firm with a high successful R&D probability will lead the investment, and the other firm follows the investment; when the value is large enough, the two firms will invest at the beginning of the period. Keywords: R&D investment; cooperation; option game; risk dominance