Multi-station observation of ionospheric disturbance of March 9 2012 and comparison with IRI-model

The magnetic storm of 9 March 2012 is a single step intense storm (Dst = −143 nT) whose main phase begins around 0100 UT and lasted for almost 11 h. The increases in NmF2 recorded 33% and 67% incidence respectively during the main and the recovery phase of the storm at the stations considered. The increase in hmF2 occurred concurrently with the increase in thickness parameter B0 between 0000 and 1100 UT, and a simultaneous decrease in the shape parameter B1 for the entire mid-latitude stations. Generally, B1 responded to the storm with a decrease away from the quiet day average, and decreased simultaneously with the increase in NmF2. B0 displays higher variability magnitude during daytime than the nighttime period. The occasional differences in the response of the ionospheric parameters to the storm event are attributed to longitudinal differences. Variation in hmF2 and NmF2 is projected to change in B1, but the rationale behind this effect on B1 is still not known and therefore left open. The two IRI options over-estimate the observed values with that of URSI higher than CCIR. The over-estimation was higher during the nighttime than the daytime for NmF2 response for the mid-latitude stations and the reverse for the equatorial station. A fairer fit of the model with the observed for all parameters over Jicamarca suggests that equatorial regions are better represented on the model. Extensive study of B1 and B0 is recommended to arrive at a better performance of IRI.     

External Cue Effects on Memory for Spatial Location within a Rotated Task Field

Abstract

We propose a mathematical model of the Path Integration (PI) process. Its core assumption is that orientations of a path are summarized by circular probability distributions. We compare our model with classical, deterministic models of PI and find that, although they are indistinguishable in terms of information encoded, the probabilistic model is more parsimonious when considering navigation strategies. We show how sensory events can enrich the probability distributions memorized, resulting in a continuum of navigation strategies, from PI to stimulus-triggered response. We analyze the combination of circular probability distributions (e.g., multicue fusion), and demonstrate that, contrary to the linear case, adding orientation cues does not always increase reliability of estimates. We discuss experimental predictions entailed by our model.     

分级时效工艺对1420Al—Li合金组织与性能的影响

研究了分级时效工艺对1420Al-Li合金组织与性能的影响，试验结果表明：经70℃／12h＋120℃／4－10h工艺分级时效处理可使1420Al-Li合金的综合力学性能得到显著的提高；分级时效工艺使1420Al-Li合金析出的δ‘相粒子分布均匀、尺寸细小。     

熔体热历史对快凝铝铁基合金显微组织不均匀性的影响

 研究合金熔体热历史对快凝Ａｌ一Ｆｅ基合金显微组织不均匀性的影响。结果表明：在熔体温度为１２５０～１３５０℃,保温时间为１０ｍｉｎ的热历史条件下,快凝显微组织中可得到在过饱和固溶体ａ－Ａｌ基体上均匀分布着２０～４０ｎｍ的ｂｃｃＡｌ１２(Ｆｅ,Ｖ)Ｓｉ弥散相组织。     

INFLUENCE OF DWELL TIME ON HIGH TEM-PERATURE LOW CYCLE FATIGUE (HTLCF) BEHAVIOR IN AN Nd-BEARING NEAR-α TITANIUM ALLOY

ＩＮＦＬＵＥＮＣＥＯＦＤＷＥＬＬＴＩＭＥＯＮＨＩＧＨＴＥＭＰＥＲＡＴＵＲＥＬＯＷＣＹＣＬＥＦＡＴＩＧＵＥ（ＨＴＬＣＦ）ＢＥＨＡＶＩＯＲＩＮＡＮＮｄＢＥＡＲＩＮＧＮＥＡＲαＴＩＴＡＮＩＵＭＡＬＬＯＹＺｈｕＺｈｉｓｈｏｕ，ＣａｏＣｈｕｎｘｉａｏ，Ｍ...     

高强耐热铸造铝硅合金的试验研究

 优化了一种高强耐热铸造铝硅合金的化学成分,确定了合理的热处理工艺,分析了该合金的强化、耐热机理。此合金具有优良的铸造性能,其机械性能：室温σｂ≥３００ＭＰａ,δ≥３％；２５０℃σｂ≥２００ＭＰａ、δ≥４％。可提供优质导弹舱体等铸件的生产。     

EFFECT OF SOLIDIFICATION RATE ON MICRO－STRUCTURES OF DIRECTIONALLYSOLIDIFIED SUPERALLOY DZ22

ＥＦＦＥＣＴＯＦＳＯＬＩＤＩＦＩＣＡＴＩＯＮＲＡＴＥＯＮＭＩＣＲＯ－ＳＴＲＵＣＴＵＲＥＳＯＦＤＩＲＥＣＴＩＯＮＡＬＬＹＳＯＬＩＤＩＦＩＥＤＳＵＰＥＲＡＬＬＯＹＤＺ２２ＬｉｕＺｈｏｎｇｙｕａｎ；ＬｉＪｉａｎｇｕｏ；ＳｈｉＺｈｅｎｇｘｉｎｇ；ＦｕＨｅｉｉ...     

时效工艺对高强度Al-Cu-Li合金断裂韧性的影响

采用Kahn撕裂法测试了高强度Al-Cu-Li合金2090在不同时效制度下的断裂韧性及其变化规律,并借助TEM和SEM对相应微观组织形貌及断口形貌进行了观察。结果表明:双级时效和应变时效均可促进T_1相析出,改善合金的断裂韧性,但这种促进作用在过时效状态下减弱;晶界PFZ的宽化和粗大晶界平衡相的析出降低合金的断裂韧性,并对时效工艺、微观组织及断裂韧性之间的关系进行了讨论。     

计算机高速缓冲存储器体系结构分析

通过对片外和片内高速缓冲存储器体系结构的总结与评价,着重分析了片内Cache与处理器核心部件、外部存储器之间的连接关系,并通过对于普林斯顿结构和哈佛结构的优缺点的讨论和分析可知,片内两级Cache结构中,一级Cache适用于哈佛结构,这样使得最接近处理器操作部件的Cache分开,消除数据引用和指令引用的冲突,远离操作部件的二级Cache则采用普林斯顿结构,可以动态调节指令和数据在其中的分配比例.这种综合的两级Cache体系结构,兼容了哈佛结构和普林斯顿结构的优势,弥补了二者的缺陷,充分发挥片内Cache的作用.     

铝合金激光冲击表面强化试验研究

 激光冲击是一种新型的材料表面强化技术。将激光冲击技术用于铝合金的强化处理，探讨了激光冲击处理的技术关键，研究了激光冲击处理对铝合金疲劳寿命的影响。研究结果表明：在优选激光参数的条件下，激光冲击处理能显著地提高铝合金的疲劳寿命。