In this paper, a Wind Direction Change Index (WI), which can describe four-dimensional spatiotemporal changes of the atmospheric circulation objectively and quantitatively, is defined to study its evolution and season...In this paper, a Wind Direction Change Index (WI), which can describe four-dimensional spatiotemporal changes of the atmospheric circulation objectively and quantitatively, is defined to study its evolution and seasonal variation. The first four modes can be obtained by EOF expansion of the zonally averaged WI. The first mode reveals the basic spatial distribution of the annually averaged WI. The second mode reflects the quasi-harmonic parts of the WI deviations. Tropical, subtropical and extratropical monsoon areas can be clearly reflected by this mode. The third mode reflects the non-harmonic parts of the WI deviations. It shows the so-called February reverse in stratospheric atmosphere as well as the asymmetric seasonal changes from spring to fall and from fall to spring due to both the land-sea distribution contrast between the Northern and Southern Hemispheres and the nonlinear effect of atmospheric and ocean fluids. The fourth mode reveals the northward advancing of the global reversed wind fields from spring to summer and their southward withdrawal from summer to autumn.展开更多
近年来,以Wi-Fi为代表的无线局域网(Wireless Local Area Network,WLAN)技术不断发展和成熟,被广泛应用到各个领域。其中,将无线网络与传统控制系统融合起来,形成具备高移动性、可扩展性和灵活性等优势的无线网络控制系统(Wireless Netw...近年来,以Wi-Fi为代表的无线局域网(Wireless Local Area Network,WLAN)技术不断发展和成熟,被广泛应用到各个领域。其中,将无线网络与传统控制系统融合起来,形成具备高移动性、可扩展性和灵活性等优势的无线网络控制系统(Wireless Networked Control Systems,WNCS),成为控制界的研究趋势之一。针对基于Wi-Fi技术的无线网络控制系统进行了研究,利用TrueTime仿真工具箱以及MATLAB/Simulink仿真环境,构建了一个WNCS的仿真系统模型,设计了相应的PID控制器,并研究了网络传输速率、采样周期等网络性能指标对系统控制性能的影响。展开更多
Temperature is a key factor that shapes the distribution of organisms.Having knowledge about how species respond to temperature is relevant to devise strategies for addressing the impacts of climate change.Aquatic ins...Temperature is a key factor that shapes the distribution of organisms.Having knowledge about how species respond to temperature is relevant to devise strategies for addressing the impacts of climate change.Aquatic insects are particularly vulnerable to climate change,yet there is still much to learn about their ecology and distribution.In the Yungas ecoregion of Northwestern Argentina,cold-and warm-adapted species of the orders Ephemeroptera,Plecoptera,and Trichoptera(EPT)are segregated by elevation.We modeled the ecological niche of South American EPT species in this region using available data and projected their potential distribution in geographic space.Species were grouped based on their ecogeographic similarity,and we analyzed their replacement pattern along elevation gradients,focusing on the ecotone where opposing thermal preferences converge.Along this interface,we identified critical points where the combined incidence of cold and warm assemblages maximizes,indicating a significant transition zone.We found that the Montane Cloud Forest holds the interface,with a particularly greater suitability at its lower boundary.The main axis of the interface runs in a N-S direction and falls between 14°C-16°C mean annual isotherms.The probability of a particular location within a basin being classified as part of the interface increases as Kira’s warmth index approaches a score around 150.Understanding the interface is critical for defining the thermal limits of species distribution and designing biomonitoring programs.Changes in the location of thermal constants related to mountainous ecotones may cause vertical displacement of aquatic insects and vegetation communities.We have recognized significant temperature thresholds that serve as indicators of suitability for the interface.As global warming is anticipated to shift these indicators,we suggest using them to monitor the imprints of climate change on mountain ecosystems.展开更多
文摘In this paper, a Wind Direction Change Index (WI), which can describe four-dimensional spatiotemporal changes of the atmospheric circulation objectively and quantitatively, is defined to study its evolution and seasonal variation. The first four modes can be obtained by EOF expansion of the zonally averaged WI. The first mode reveals the basic spatial distribution of the annually averaged WI. The second mode reflects the quasi-harmonic parts of the WI deviations. Tropical, subtropical and extratropical monsoon areas can be clearly reflected by this mode. The third mode reflects the non-harmonic parts of the WI deviations. It shows the so-called February reverse in stratospheric atmosphere as well as the asymmetric seasonal changes from spring to fall and from fall to spring due to both the land-sea distribution contrast between the Northern and Southern Hemispheres and the nonlinear effect of atmospheric and ocean fluids. The fourth mode reveals the northward advancing of the global reversed wind fields from spring to summer and their southward withdrawal from summer to autumn.
文摘近年来,以Wi-Fi为代表的无线局域网(Wireless Local Area Network,WLAN)技术不断发展和成熟,被广泛应用到各个领域。其中,将无线网络与传统控制系统融合起来,形成具备高移动性、可扩展性和灵活性等优势的无线网络控制系统(Wireless Networked Control Systems,WNCS),成为控制界的研究趋势之一。针对基于Wi-Fi技术的无线网络控制系统进行了研究,利用TrueTime仿真工具箱以及MATLAB/Simulink仿真环境,构建了一个WNCS的仿真系统模型,设计了相应的PID控制器,并研究了网络传输速率、采样周期等网络性能指标对系统控制性能的影响。
文摘Temperature is a key factor that shapes the distribution of organisms.Having knowledge about how species respond to temperature is relevant to devise strategies for addressing the impacts of climate change.Aquatic insects are particularly vulnerable to climate change,yet there is still much to learn about their ecology and distribution.In the Yungas ecoregion of Northwestern Argentina,cold-and warm-adapted species of the orders Ephemeroptera,Plecoptera,and Trichoptera(EPT)are segregated by elevation.We modeled the ecological niche of South American EPT species in this region using available data and projected their potential distribution in geographic space.Species were grouped based on their ecogeographic similarity,and we analyzed their replacement pattern along elevation gradients,focusing on the ecotone where opposing thermal preferences converge.Along this interface,we identified critical points where the combined incidence of cold and warm assemblages maximizes,indicating a significant transition zone.We found that the Montane Cloud Forest holds the interface,with a particularly greater suitability at its lower boundary.The main axis of the interface runs in a N-S direction and falls between 14°C-16°C mean annual isotherms.The probability of a particular location within a basin being classified as part of the interface increases as Kira’s warmth index approaches a score around 150.Understanding the interface is critical for defining the thermal limits of species distribution and designing biomonitoring programs.Changes in the location of thermal constants related to mountainous ecotones may cause vertical displacement of aquatic insects and vegetation communities.We have recognized significant temperature thresholds that serve as indicators of suitability for the interface.As global warming is anticipated to shift these indicators,we suggest using them to monitor the imprints of climate change on mountain ecosystems.
