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Understanding the impact of environmental factors on crop phenology is significant in predicting crop growth stages, agricultural decision-making, and yield estimation. Here, using Moderate Resolution Imaging Spectroradiometer time-series data, we present phenological detection mechanisms and an explanation for the phenological variability linked to environmental drivers, such as cumulative temperature and soil salinity, for winter wheat (Triticum aestivum L.) in the Yellow River Delta in 2013. The 8-day normalized difference vegetation index was fitted to a double Gaussian function. Phenological phases, such as the green-up and heading phases, were extracted using maximum curvature approaches. The spatial characteristics of the phenological patterns were investigated. The relationships between the phenological phases and cumulative temperature were explored. Then, the relationships between the phenological phases and soil salinity were evaluated by selecting sites with similar soil fertility and temperature forcing. This study concluded that the regional average green-up date occurred on 5 March, and the regional average heading date occurred on 9 May. The spatial distributions of the green-up and heading phases showed a gradual delay from the southwest to the northeast and from the south to the north. The green-up phase lagged 4–5 days for every 10 degree days that the cumulative temperature decreased. The heading phase lagged 1–2 days for every 10 degree days that the cumulative temperature decreased. The green-up phase in a non-salinization region might be approximately 5–9 days earlier than that in a severe or moderate salinization region. The heading phase in a severe region might occur approximately 1–8 days earlier than that in a non-salinization or moderate salinization region. The method proposed in this article may be useful for understanding the impact of temperature and soil salinity on phenology and could be used to better manage winter wheat in coastal salinization areas. 相似文献
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84.
Leif?W.?Lundmark Chong?OhEmail author J.?Cameron?Verhaal 《Information Systems Frontiers》2017,19(6):1407-1422
Drawing on the organizational legitimacy literature, we propose and test a set of hypotheses arguing that social media, an artifact of information technology, serves as a mechanism for conferring legitimacy in the market for initial public offerings (IPOs). The extant literature identifies third-party authorities, such as traditional media outlets and industry analysts, as a valuable source of organizational legitimacy. Social media and micro-blogging, however, remain outside current classifications of the phenomenon. This study theoretically develops and empirically tests a new mechanism in the legitimation process: the direct interaction with potential investors and society-at-large via social media. Our findings indicate broad support that having a Twitter account, and the extent to which a firm utilizes Twitter, is associated with systematically higher levels of IPO underpricing. Moreover, we find support that social media variables external to the firm, including number of followers and retweets, also impact the level of underpricing in an IPO. In conclusion, we highlight the emerging role of social media in processes of legitimation and invite additional research at the intersection of IS and management. 相似文献
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通过问卷对南昌地区六所本科院校的1 200名大学生的网络使用情况进行调查,发现平均每天上网的时间、网恋的经历、上网费用的预算与网络依赖的程度存在显著的正相关关系,每周户外运动次数与网络依赖程度存在显著的负相关关系。同时,大部分大学生的上网动机为娱乐和游戏,上网的地点基本集中在寝室和校内的网吧,上网的时间段为18:00~23:00之间。根据调查情况,对大学生健康使用网络提出了相应的建议。 相似文献
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蛇形益智魔方是智力魔方的一种,由27个两两相连的小正方体组成。文章通过计算机图形学的概念建立空间三维坐标模型,对模型中关键点进行分析归类,对空间中每个方块体可能的坐标点进行了递归公式推导,最后利用三维空间坐标的遍历算法来寻找蛇形魔方所有可能的解,指出了模型的使用前景。 相似文献
89.
首先阐明电源受限嵌入式系统的定位休眠激活方案的基本工作原理;然后介绍MCP2030的三方向磁场检测接收、低功耗以及多种节能工作模式的显著特点;最后以有源射频标签为例介绍了具体的软硬件设计和应用实现. 相似文献
90.
Topological methods are often used to describe flow structures in fluid dynamics and topological flow field analysis usually relies on the invariants of the associated tensor fields. A visual impression of the local properties of tensor fields is often complex and the search of a suitable technique for achieving this is an ongoing topic in visualization. This paper introduces and assesses a method of representing the topological properties of tensor fields and their respective flow patterns with the use of colors. First, a tensor norm is introduced, which preserves the properties of the tensor and assigns the tensor invariants to values of the RGB color space. Secondly, the RGB colors of the tensor invariants are transferred to corresponding hue values as an alternative color representation. The vectorial tensor invariants field is reduced to a scalar hue field and visualization of iso-surfaces of this hue value field allows us to identify locations with equivalent flow topology. Additionally highlighting by the maximum of the eigenvalue difference field reflects the magnitude of the structural change of the flow. The method is applied on a vortex breakdown flow structure inside a cylinder with a rotating lid. 相似文献