模态pushover分析方法的研究和改进

鉴于传统pushover方法不能考虑结构高阶振型的贡献,从而难以应用到高层结构中,有学者提出采用考虑多阶振型组合作用的模态pushover分析方法。本文通过考虑结构屈服后地震作用发生变化这一特性,对此方法进行了改进并通过算例进行了验证。结果表明本文改进的方法有很好的精度。     

Construction of the OKJ teleconnection index

This study focuses on the construction of an index to measure Okhotsk–Japan (OKJ) teleconnection pattern that mainly occurs in early summer. There are three major results presented here. The first is that four indices were developed to describe the OKJ pattern occurring in the monthly mean height field by using one point correlation and empirical orthogonal function (EOF) analysis. Although there is no substantial difference among them, the third OKJ index (OKJ-III) gives a better result for the OKJ pattern when correlated with height field at 500 hPa in June. Second, there exists a significant positive correlation between the East Asian monsoon index and the OKJ-III in June. The positive OKJ-III is associated with the positive anomalies of precipitation rate to the south of the Yangtze River and Northeast China in June and negative anomalies of the surface air temperature over Japan in June through August and vice versa. All of these coincide well with the features of Rossby wave propagation in OKJ pattern that were summarized in previous studies. This index that simply represents the strength of the OKJ propagation can be used as a diagnostic tool to assess East Asian summer monsoon climate, especially for the month of June. Third, the OKJ pattern can be detected by using the first principal component of the EOF analysis in June 500 hPa height field, and it accounts for large portion of the total variance. Such a strong OKJ signal was not found in the rest of the summer months, i.e., July and August. These results strongly suggest the importance of the OKJ pattern in the East Asian circulation of early summer.     

High-temperature neutron diffraction study of deuterated brucite

To study the structural behavior of brucite at high temperature, we conducted in situ neutron diffraction experiments of a deuterated brucite powder sample, Mg(OD)₂, in the temperature range 313–583 K. The sample was stable up to 553 K, above which it started to decompose into periclase (MgO) and D₂O vapor. Rietveld analyses of the obtained data were performed using both single-site and three-site split-atom hydrogen models. Our results show that with increasing temperature, unit-cell parameter c increases at a rate ~7.7 times more rapidly than a. This large anisotropy of thermal expansion is primarily due to rapid increase in the interlayer thickness along the c-axis on heating. The amplitudes of thermal vibration for Mg, O, and D increase linearly with increasing temperature; however, the rate of the increase for the lighter D is much larger. In addition, D vibrates anisotropically with a higher magnitude within the (001) plane, as confirmed by our first-principles phonon calculations. On heating, the interatomic distances between a given D and its associated O and D from the adjacent [MgO₆] layer increase, whereas the O–D bond length decreases. This behavior suggests weakened D···O and D···D interlayer interactions but strengthened O–D bonding with increasing temperature.     

虾池生态系浮游生物亚模型

利用ＳＴＥＬＬＡＩＩ建立虾池生态系浮游生物亚模型,模拟虾池生态系中浮游生物之间的相互作用及生物量变化。模型中的生物状态变量是浮游植物和浮游动物,表达为能量单位ｋＪ／ｍ２。光和温度为强制函数。该模型模拟在一定的光照和温度下,浮游植物、浮游动物和ＤＩＰ在６月份到９月份４个月的变化,模拟结果与实测结果变化趋势非常一致。     

(Exergy)在湖泊生态系统建模中的应用

基于达尔文“适者生存”理论的热力学表述，本文把热力学概念“（Exergy）”作为一些重要模型参数的目标函数引入湖泊生态动力学模型．应用拥控制下的参数组合模拟程序实现了参数随时间的变化，并通过变化的模型参数来反映湖泊生态系统中物种组成和生态结构随时间的变化．这一改进克服了以往模型刚性较强、适应性差和生态系统特性考虑少的缺陷，该改进的湖泊生态动力学模型被成功用于滇池生态系统的模拟．     

A potential nitrogen sink discovered in the oxygenated Chukchi Shelf waters of the Arctic

The western Arctic Shelf has long been considered as an important sink of nitrogen because high primary productivity of the shelf water fuels active denitrification within the sediments, which has been recognized to account for all the nitrogen (N) removal of the Pacific water inflow. However, potentially high denitrifying activity was discovered within the oxygenated Chukchi Shelf water during our summer expedition. Based on ¹⁵N-isotope pairing incubations, we estimated denitrification rates ranging from 1.8 ± 0.4 to 75.9 ± 8.7 nmol N₂ L^?1 h^?1. We find that the spatial pattern of denitrifying activity follows well with primary productivity, which supplies plentiful fresh organic matter, and there was a strong correlation between integrated denitrification and integrated primary productivity. Considering the active hydrodynamics over the Chukchi Shelf during summer, resuspension of benthic sediment coupled with particle-associated bacteria induces an active denitrification process in the oxic water column. We further extrapolate to the whole Chukchi Shelf and estimate an N removal flux from this cold Arctic shelf water to be 12.2 Tg-N year^?1, which compensates for the difference between sediment cores incubation (~ 3 Tg-N year^?1) and geochemical estimation based on N deficit relative to phosphorous (~ 16 Tg-N year^?1). We infer that dynamic sediment resuspension combined with high biological productivity stimulates intensive denitrification in the water column, potentially creating a nitrogen sink over the shallow Arctic shelves that have previously been unrecognized.     

浅谈山西省古元古代末期火山岩的构造背景

对山西古元古代末期火山岩的构造属性进行了研究,旨在为解决现今国内外关于古/中元古界(代)分界问题的分岐提供依据。该期火山岩角度不整合于具活动大陆边缘特征的结晶基底之上。无论是汉高山群(或小两岭组)还是西洋河群(—熊耳群),均呈SEE向展布,熔岩占绝对优势,偶见碎屑岩;以裂隙(串珠状)宁静式溢流喷发为主,同期的基性侵入岩墙群为其岩浆上升的通道。岩性以安山岩-玄武安山岩为主,含少量玄武岩和流纹岩。岩石斑晶为辉石和斜长石,偶见角闪石和黑云母。岩石地球化学富大离子亲石元素和轻稀土元素,亏损高场强元素,w(Th)>w(Ta)。全岩εNd(t)值和εHf(t)值均为负值,在SiO₂-K₂O图解中以SH+HKCA系列为主,为钾质火成岩系列。该期火山岩是古元古代中晚期华北克拉通结晶基底的西部陆块与东部陆块碰撞拼合的延续,为后碰撞火山弧岩浆。     

玉米生育模拟模式区域应用研究之水分利用子模式

应用ＳＰＡＣ系统水分循环原理,建立了适合玉米生育的水分利用子模式;利用该模式模拟分析了辽宁省海城市、昌图县、阜新蒙古族自治县３ 地区的土壤水分动态变化过程、农田蒸发和蒸腾过程,并结合作物生物学特性建立了水分胁迫对作物生理过程的影响函数。经计算,该模式模拟结果（ 除个别期次外） 的相对误差范围海城为０．１３％ ～３４．９％ ,昌图为０ ．４４％ ～３２ ．５ ％ ,阜新为２．６％ ～２６．１％ 。