前人研究认为,受海因里希1(Heinrich Stadial 1,HS1)早期(约18.3—16.3cal ka BP)北半球降温的影响,热带辐合带(intertropical convergence zone,ITCZ)雨带的平均位置会向南移动。但是,最新结果发现,HS1早期北半球低纬度地区(3oN—9oN)...前人研究认为,受海因里希1(Heinrich Stadial 1,HS1)早期(约18.3—16.3cal ka BP)北半球降温的影响,热带辐合带(intertropical convergence zone,ITCZ)雨带的平均位置会向南移动。但是,最新结果发现,HS1早期北半球低纬度地区(3oN—9oN)呈现湿润水文条件,而其南北部却同步出现干旱。可见HS1早期ITCZ对北大西洋降温事件的响应方向及位移幅度仍存争议。孟加拉湾的海洋炭屑记录保存了周边陆地大量气候成因古火事件的信息。研究发现,在HS1早期(18.3—16.3 cal ka BP),位于9°54′N的YDY09孔的炭屑总浓度与木本型炭屑百分比均降至最低,而草本型炭屑百分比则有所上升,这表明火灾发生强度急剧降低。这一变化,结合有孔虫和石笋δ^(18)O记录所揭示的降水减少信号,可能源于当时气候干旱与温度降低共同导致的植被退化。该结论说明炭屑、孢粉与有孔虫等其他指标重建的印度夏季风降水结果一致,也与来自10°N的YDY10岩芯和15°N的E87-32B岩芯中常绿阔叶林花粉低值所反映的干旱情形相符。同期,苏门答腊岛2个孔(分别位于6°N和6°S)的炭屑和孢粉含量也分别显示湿润和干旱,反映其炭屑和孢粉源区当时处于ITCZ雨带范围内部与外部区域。炭屑与孢粉记录共同揭示,HS1早期在10°N至6°S范围之外存在干旱证据;结合苏门答腊岛6°N孔的湿润证据,间接支持了该时期ITCZ位置在6°N两侧。展开更多
An increasing number of annealing furnaces have recently been using cheaper and cleaner natural gas （NG） instead of liquefied petroleum gas （LPG） as fuel gas.However,the fuel gas of the furnaces often needs to be ...An increasing number of annealing furnaces have recently been using cheaper and cleaner natural gas （NG） instead of liquefied petroleum gas （LPG） as fuel gas.However,the fuel gas of the furnaces often needs to be changed when NG supply is not adequate or when LPG becomes cheaper.Usually,changing the fuel gas involves changing various equipment as well as control parameters for instruments and the control system and hence is time consuming.Therefore,it is important to develop a quick process for changing fuel gas.This study discusses the techniques for quickly changing fuel gas in an annealing furnace.These techniques deal with the design of the pipe,valve and burner,the selection of the flow meter and the flow control valve,the switch of the software and parameters for the control system,as well as the operation,commissioning and hot test of the furnace when the fuel gas is changed.Using these techniques,it is possible to change fuel gas in 6 h.展开更多
文摘前人研究认为,受海因里希1(Heinrich Stadial 1,HS1)早期(约18.3—16.3cal ka BP)北半球降温的影响,热带辐合带(intertropical convergence zone,ITCZ)雨带的平均位置会向南移动。但是,最新结果发现,HS1早期北半球低纬度地区(3oN—9oN)呈现湿润水文条件,而其南北部却同步出现干旱。可见HS1早期ITCZ对北大西洋降温事件的响应方向及位移幅度仍存争议。孟加拉湾的海洋炭屑记录保存了周边陆地大量气候成因古火事件的信息。研究发现,在HS1早期(18.3—16.3 cal ka BP),位于9°54′N的YDY09孔的炭屑总浓度与木本型炭屑百分比均降至最低,而草本型炭屑百分比则有所上升,这表明火灾发生强度急剧降低。这一变化,结合有孔虫和石笋δ^(18)O记录所揭示的降水减少信号,可能源于当时气候干旱与温度降低共同导致的植被退化。该结论说明炭屑、孢粉与有孔虫等其他指标重建的印度夏季风降水结果一致,也与来自10°N的YDY10岩芯和15°N的E87-32B岩芯中常绿阔叶林花粉低值所反映的干旱情形相符。同期,苏门答腊岛2个孔(分别位于6°N和6°S)的炭屑和孢粉含量也分别显示湿润和干旱,反映其炭屑和孢粉源区当时处于ITCZ雨带范围内部与外部区域。炭屑与孢粉记录共同揭示,HS1早期在10°N至6°S范围之外存在干旱证据;结合苏门答腊岛6°N孔的湿润证据,间接支持了该时期ITCZ位置在6°N两侧。
文摘An increasing number of annealing furnaces have recently been using cheaper and cleaner natural gas （NG） instead of liquefied petroleum gas （LPG） as fuel gas.However,the fuel gas of the furnaces often needs to be changed when NG supply is not adequate or when LPG becomes cheaper.Usually,changing the fuel gas involves changing various equipment as well as control parameters for instruments and the control system and hence is time consuming.Therefore,it is important to develop a quick process for changing fuel gas.This study discusses the techniques for quickly changing fuel gas in an annealing furnace.These techniques deal with the design of the pipe,valve and burner,the selection of the flow meter and the flow control valve,the switch of the software and parameters for the control system,as well as the operation,commissioning and hot test of the furnace when the fuel gas is changed.Using these techniques,it is possible to change fuel gas in 6 h.
