King George Island, situated in the South Shetland Islands archipelago, is one of the most visited sites in Antarctica. Antarctica attracts much attention because it is one of the most sensitive areas under the influe...King George Island, situated in the South Shetland Islands archipelago, is one of the most visited sites in Antarctica. Antarctica attracts much attention because it is one of the most sensitive areas under the influence of global warming. To understand its hydrochemistry characteristics, we collected various types of water samples, including samples from streams, meltwaters, ground waters, snow and ice from around the Great Wall Station, Fildes Peninsula, King George Island, from January to February, 2015. Major ions, alkalinities, silicate, pH, dissolved oxygen, temperature, and electric conductivities were measured. Several approaches were applied to identify processes that af fect the hydrochemistry on Fildes Peninsula, including ternary diagrams, principal components analysis and cluster analysis. Our data suggest that atmospheric seasalt deposition is the main factor controlling the hydrochemistry on Fildes Peninsula. After atmospheric influences were corrected for seasalt, we defined the weathering of local rocks to be another important factor on the Peninsula's hydrochemistry. Processes such as Ca dissolution from the Ca-bearing basalt, Si loss through secondary mineralization and biological uptake influence the chemical composition of runof fs on the peninsula. Cluster analysis identified 4 groups of streams based on their hydrochemical features, which reflect their original weathering characters under icecap and the combined effects with melt snow, biological activity and the anthropogenic input.展开更多
By 2018, China had conducted 34 scientific explorations in Antarctica spearheaded by the Chinese National Antarctic Research Expedition(CHINARE). Since the first CHINARE over 30 years ago, considerable work has been u...By 2018, China had conducted 34 scientific explorations in Antarctica spearheaded by the Chinese National Antarctic Research Expedition(CHINARE). Since the first CHINARE over 30 years ago, considerable work has been undertaken to promote the development of techniques for the observation of surface and upper-air meteorological elements, and satellite image and data reception systems at Chinese Antarctic stations and onboard Chinese icebreakers have played critical roles in this endeavor. The upgrade of in situ and remote sensing measurement methods and the improvement of weather forecasting skill have enabled forecasters to achieve reliable on-site weather forecasting for the CHINARE. Nowadays, the routing of icebreakers, navigation of aircraft, and activities at Chinese Antarctic stations all benefit from the accurate weather forecasting service. In this paper, a review of the conventional meteorological measurement and operational weather forecasting services of the CHINARE is presented.展开更多
高压直流(high-voltage direct current,HVDC)传输系统受端近区交流电网故障可引起直流连续换相失败,甚至导致直流闭锁或电压崩溃事故,引起大面积停电风险。为实现动态调节直流首次换相失败恢复过程中的直流电流指令,以达到抑制直流连...高压直流(high-voltage direct current,HVDC)传输系统受端近区交流电网故障可引起直流连续换相失败,甚至导致直流闭锁或电压崩溃事故,引起大面积停电风险。为实现动态调节直流首次换相失败恢复过程中的直流电流指令,以达到抑制直流连续换相失败的目的,提出基于电压限流参数优化的直流传输系统换相失败抑制策略。在分析引起直流连续换相失败影响因素及逆变侧换流站与外部电网无功交互特性的基础上,以低压限流环节作为研究对象,采用粒子群算法对低压限流控制环节进行多分段拐点参数优化,克服常规低压限流环节单一线性的缺陷,实现在受端交流系统发生故障时逆变侧换流站的动态无功需求调整,进而抑制直流连续换相失败。最后通过仿真对比证明所提方法的有效性。展开更多
基金Supported by the Chinese Arctic and Antarctic Administration(No.2014GW08008)the SKLEC/ECNU(No.2011KYYW02)the National Natural Science Foundation of China(No.41676175)
文摘King George Island, situated in the South Shetland Islands archipelago, is one of the most visited sites in Antarctica. Antarctica attracts much attention because it is one of the most sensitive areas under the influence of global warming. To understand its hydrochemistry characteristics, we collected various types of water samples, including samples from streams, meltwaters, ground waters, snow and ice from around the Great Wall Station, Fildes Peninsula, King George Island, from January to February, 2015. Major ions, alkalinities, silicate, pH, dissolved oxygen, temperature, and electric conductivities were measured. Several approaches were applied to identify processes that af fect the hydrochemistry on Fildes Peninsula, including ternary diagrams, principal components analysis and cluster analysis. Our data suggest that atmospheric seasalt deposition is the main factor controlling the hydrochemistry on Fildes Peninsula. After atmospheric influences were corrected for seasalt, we defined the weathering of local rocks to be another important factor on the Peninsula's hydrochemistry. Processes such as Ca dissolution from the Ca-bearing basalt, Si loss through secondary mineralization and biological uptake influence the chemical composition of runof fs on the peninsula. Cluster analysis identified 4 groups of streams based on their hydrochemical features, which reflect their original weathering characters under icecap and the combined effects with melt snow, biological activity and the anthropogenic input.
基金supported by the project of National Key R&D Program of China(Grant no.2016YFC1402705)
文摘By 2018, China had conducted 34 scientific explorations in Antarctica spearheaded by the Chinese National Antarctic Research Expedition(CHINARE). Since the first CHINARE over 30 years ago, considerable work has been undertaken to promote the development of techniques for the observation of surface and upper-air meteorological elements, and satellite image and data reception systems at Chinese Antarctic stations and onboard Chinese icebreakers have played critical roles in this endeavor. The upgrade of in situ and remote sensing measurement methods and the improvement of weather forecasting skill have enabled forecasters to achieve reliable on-site weather forecasting for the CHINARE. Nowadays, the routing of icebreakers, navigation of aircraft, and activities at Chinese Antarctic stations all benefit from the accurate weather forecasting service. In this paper, a review of the conventional meteorological measurement and operational weather forecasting services of the CHINARE is presented.
文摘高压直流(high-voltage direct current,HVDC)传输系统受端近区交流电网故障可引起直流连续换相失败,甚至导致直流闭锁或电压崩溃事故,引起大面积停电风险。为实现动态调节直流首次换相失败恢复过程中的直流电流指令,以达到抑制直流连续换相失败的目的,提出基于电压限流参数优化的直流传输系统换相失败抑制策略。在分析引起直流连续换相失败影响因素及逆变侧换流站与外部电网无功交互特性的基础上,以低压限流环节作为研究对象,采用粒子群算法对低压限流控制环节进行多分段拐点参数优化,克服常规低压限流环节单一线性的缺陷,实现在受端交流系统发生故障时逆变侧换流站的动态无功需求调整,进而抑制直流连续换相失败。最后通过仿真对比证明所提方法的有效性。
