结构最优主动调谐质量阻尼器风致振动控制的研究

基于我国现行的风荷载规范,建立了在风荷载作用下结构-主动调谐质量阻尼器(ATMD)系统的动力方程。定义ATMD最优参数准则为:结构-ATMD系统的位移或加速度响应方差的最小化。ATMD有效性的评价准则为:设置ATMD结构的最小化位移或加速度响应方差与未设置ATMD结构的位移或加速度响应方差之比(分别称为位移和加速度减振系数)。根据上述准则,在频域内数值研究了结构自振频率、标准化加速度反馈增益系数、质量比对ATMD系统的最优参数(包括最优频率比和阻尼比)、有效性和冲程的影响。此外,为了比较的目的,论文同时考虑了结构TMD风致振动控制的情况。     

Differentiation of the Agonists and Antagonists of the α7 Nicotinic Acetylcholine Receptor

The α7 nicotinic acetylcholine receptors(nAChRs) are widely expressed in the central and peripheral nervous systems and are important drug targets for the treatment of neurological diseases. However, differentiation of the agonists and antagonists of the nAChR is difficult. In this study we aimed to develop a reliable and efficient computational approach for differentiation of the agonists from the antagonists of the nAChR based on a systematical analysis of 123 ligands(87 agonists, 12 partial agonists, and 24 antagonists) binding with the extracellular domain of the α7 n AChR chimera. Our results suggest that the ligand size and ligand binding affinity cannot differentiate the agonists from the antagonists of the nAChR. The ligand efficiency that considers both ligand binding affinity and size for the agonists is overall more left shifted in comparison to the antagonists, but the values of the ligand efficiency still cannot differentiate the agonists from the antagonists unless the values are either relatively high(more than-0.3 kcal mol-1) or relatively low(less than-0.45 kcal mol-1). Our results suggest that accurate prediction of the agonist or antagonist of the nAChR is challenging and the ligand innate configuration has to be considered as an extra for differentiation of the agonists from the antagonists of the nAChR.     

新冠肺炎疫情时期四川盆地大气污染成因分析

由于新型冠状肺炎病毒(COVID-19)的爆发,中国从2020年春节起实施了限制出行、交通管制等一系列措施,污染物排放量大幅度减少,但四川盆地区域仍出现了多次轻度空气污染事件。本文结合空气质量观测数据与WRF-Chem模式模拟分析了疫情封控减排时期四川盆地污染的时空分布及成因。四川盆地区域二氧化氮(NO₂)因人为活动减排从35.0μg·m^-3下降至20.2μg·m^-3,减少比例约为40%～60%,而臭氧(O₃)因NO_X-VOCs-O₃的非线性关系以及四川盆地区域氮氧化物(NO_X)、挥发性有机物(VOCs)排放与减排的不均衡反而从27.5μg·m^-3上升至41.4μg·m^-3,在重庆甚至增幅高达100%,进而促进了四川盆地区域气态污染物的氧化和二次细颗粒物的生成。疫情减排对污染的影响存在较为显著的区域差异,在成都、重庆地区,二次污染的生成一定程度上抵消了一次污染物减排的影响,二次污染物与一次污...     

OTFS水声通信技术研究现状与展望

正交时频空调制是近年来提出的一种用于高速移动无线通信场景的调制技术,通过将时变多径信道转换到时延–多普勒域,使得所有符号都经历几乎相同且变化缓慢的稀疏信道。与正交频分复用系统相比, 正交时频空技术具有较低的峰均功率比,且能够有效抵抗多普勒效应,在高时延、高多普勒的信道条件下具备性能优势。简要介绍了正交时频空技术的基本原理,以及目前无线电及水声通信领域正交时频空技术研究与应用现状,梳理了正交时频空技术在工程应用中亟待解决的关键问题,如波形设计、信道估计和均衡以及接收机结构设计等。最后对正交时频空技术在水声通信系统中面临的挑战和应用前景进行了分析和展望。     

净化湖泊饮用水源的物理-生态工程实验研究

我国许多历史上水质优良的湖泊水源区已污染严重污染,净化饮用水源刻不容缓。本文介绍了自１９９１年以来太源进行的物理－生态工程的部分研究成果。着重介绍在太湖的重富营养湖湾－五里湖无锡中桥自来水厂水源区的静态和抽水动态实验。     

2014—2019年北京和南京地区PM2.5和臭氧质量浓度相关性研究

自2014年以来,中国细颗粒物（PM_2.5）浓度大幅度下降,但臭氧（O₃）浓度逐年缓慢上升,厘清PM_2.5和O₃（P-O）相关性尤为关键.在本研究中,2014—2019年北京和南京PM_2.5年均质量浓度下降幅度分别为-6.86和-6.15 μg·m^-3·a^-1;而日最大8小时平均O₃质量浓度（MDA8 O₃）年均增长幅度为1.50和1.75 μg·m^-3·a^-1.研究期间,北京地区MDA8 O₃质量浓度小于100 μg·m^-3,P-O呈负相关;而当质量浓度大于100 μg·m^-3时,P-O为正相关.通过Pearson相关系数研究P-O两者相关性.在两个城市每月相关性分析中,在每日时间尺度5—9月为强的正相关;而小时时间尺度11月至次年2月趋于负相关.在北京,P-O每月和季节相关性变化大于南京.在日变化中,夏季在16时为强的正相关,春秋两季在13—17时为弱的正相关,而在春、秋和冬季8时,却为强的负相关.     

Magmatic and hydrothermal zircon growth during multiple orogenic cycles in an evolving mantle wedge

The Hongseong area of the Hongseong-Imjingang Belt in the central-western Korean Peninsula forms part of a subduction-collision system that is correlated with the Qinling-Dabie-Sulu Belt in China. Several serpentinized ultramafic bodies carrying blocks of metamorphosed mafic rocks occur in this area. Here we investigate zircon grains in serpentinites from Bibong(BB) and Wonnojeon(WNJ), and high-pressure(HP) mafic granulite from Baekdong(BD) localities based on U-Pb, REE and Lu-Hf analyses. The zircons from BD HP mafic granulite show distinct age peaks at 838 Ma, 617 Ma and 410 Ma, with minor peaks at1867 Ma, 1326 Ma and 167 Ma. The Neoproterozoic age peaks in these rocks as well as in the serpentinites suggest subduction-related melt-fluid interaction in the mantle wedge at this time. The older zircon grains ranging in age from the Early to Middle Paleoproterozoic might represent detrital grains from the basement rocks transferred to the wedge mantle through sediment subduction. The BD HP mafic granulite shows a Middle Paleozoic age peak(Devonian; 410 Ma). The 242-245 Ma age peaks in the compiled age data of zircon grains serpentinites from BB and WNJ correspond to a major Triassic event that further added melts and fluids into the ancient mantle wedge to crystallize new zircons. In the chondrite normalized rare earth element diagram, the magmatic zircon grains from the studied rocks show LREE depletion and HREE enrichment with sharply negative Eu and Pr anomalies and positive Ce and Sm anomalies. The REE patterns of hydrothermal zircons show LREE enrichment, and relatively flat patterns with negative Eu anomaly. Zircon Hf signature from the WNJ serpentinite show negative εHf(t)(-18.5 and-23.5) values indicating an enriched mantle source with TDM in the range of 1614 Ma and1862 Ma. Zircons from the BD HP mafic granulite also show slightly negative εHf(t)(average-4.3) and TDM in the range of 1365-1935 Ma. Our study provides evidence for multiple zircon growth in an evolving mantle wedge that witnessed melt and fluid interaction during different orogenic cycles.     

青藏高原北部巴颜喀拉构造带基底隆起的地震学证据

过去曾笼统地认为巴颜喀拉构造带上万米的堆积主要是三叠系的复理石沉积。通过对沱沱河-格尔木深地震剖面资料的再认识发现，巴颜喀拉构造带的结晶基底埋深仅5km左右，比金沙江断裂带以南的羌塘地块北缘和昆仑山南缘的基底埋藏深度都要浅。进一步对青藏公路以东横穿巴颜喀拉构造带的几条深地震测深剖面进行分析，发现该基底隆起一直顺构造走向延伸，向东贯穿了整个构造带，推测它是扬子古陆块的残余。     

1998年和1999年长江流域汛期降水及其季风流管特征

１９９８年６、７月长江中游雨量集中,两月总雨量７３４．７ｍｍ年６月长江中下游雨量分别为３２５．５、６３６．２ｍｍ,安庆、上海月雨量均为１９４９年以来同期最高值。南亚高压东北侧存在一高空急流,中低层西太平洋副热带高压西北侧为一低空急流,两急流轴线间为宽广的近东向垂直上升运动区,并伴为湿舌和涡旋存在,构成季风流管。长江流域受季风流管影响,产生大到暴雨。     

基于WebGIS的地震目录数据发布系统研究

介绍了ArcIMS的体系结构、特点及技术优势。构建了基于ArcIMS的地震目录等信息的发布系统,提出了系统设计的思想、功能、特点及实现的方法,并通过实例操作演示了基于WebGIS的地震目录数据发布系统。