Model–proxy comparison for overshoot phenomenon of Atlantic thermohaline circulation at Bφlling–Allerφd

The overshoot phenomenon of the Atlantic thermohaline circulation(THC) is a transient climate response to meltwater forcing and could induce intense climate change by increasing the magnitudes of Atlantic THC changes at the end of meltwater discharges. This phenomenon was formally presented with the successfully simulated Bφlling–Allerφd(BA) event in the first transient simulation of the last deglaciation with fully coupled model NCAR-CCSM3(TraCE-21K). Currently, not all proxy records of Atlantic THC support the occurrence of the THC overshoot at BA. Commonly used THC proxy from Bermuda Rise(GGC5) does not exhibit THC overshoot at BA but other proxies such as TTR-451 at Eirik Drift do. How to interpret this regional discrepancy of proxy records is a key question for the validation of the Atlantic THC overshoot at BA. Here, we show that the vigor of deep circulation varies regionally during the Atlantic THC overshoot at BA in TraCE-21 K simulation, and this regional discrepancy in the simulation is consistent with that in the marine sediment records in North Atlantic. The consistent model–proxy evidence supports the occurrence of Atlantic THC overshoot at BA.

冲击压缩下玻璃样品后自由表面速度的过冲现象

实验发现当飞片碰撞玻璃样品产生的冲击载荷超过一定值后 ,玻璃样品后自由表面速度时程曲线上有“过冲现象” ,即速度上升到最大值后 ,立即开始下降 ,其时间的开始部分类似于三角波。通过高速摄影和VISAR等测试手段对这一现象进行了较系统的研究 ,发现其与玻璃样品后自由表面附近的破碎有关 ,建立了描述这一破坏现象的损伤演化方程 ,并进行了数值模拟。计算结果和实验结果吻合 ,表明对这个现象的解释是合理的。

基于SIRS传染病模型的银行风险传染机制研究

借助生物学SIRS传染病模型,对银行风险传染过程进行研究,重点考察风险感染率、恢复率和免疫缺失率对银行系统内风险传染的作用。结果表明:风险传染过程中存在类似疫情爆发的“超调”现象,会使各类银行节点数显著脱离最终稳态水平;系统最终稳态水平仅由感染率、恢复率及免疫缺失率决定;降低感染率和免疫缺失率、提高恢复率均能有效减少系统稳态后的感染银行数,从而抑制风险的蔓延趋势,但前者会延长风险传染持续的时间,后者的时间则会缩短。

自动称过冲现象分析及其抑制

本文对自动称的过冲现象做了详细的分析说明,并提出了具体的解决方法,对从事自动称的设计、调试及使用人员有一定的参考价值。

一种用于DC-DC开关电源芯片的新型软启动电路

设计了一种应用于DC-DC开关电源芯片中的新型软启动电路。其核心是一种带电容倍增结构的软启动电路,电路结构简单、易于实现,采用密勒电容倍增技术,极大地减小了所需电容尺寸,进而显著减小了电路版图面积。该软启动电路已在基于0.5μm BCD工艺设计的DCDC开关电源芯片中实现并进行了验证,测试结果表明DC-DC开关电源芯片输出电压逐步上升,没有产生过冲现象,芯片在3 ms左右完成启动开始正常工作。DC-DC开关电源芯片面积为1.88 mm×2.00 mm,软启动电路模块面积仅为0.2 mm×0.07 mm。