Characterization of displacement demand for elastic and inelastic SDOF systems

The results of a research concerning the characterization of elastic and inelastic displacement spectral demand as a function of magnitude, source-to-site distance, and soil type are presented. The displacement spectra were computed for single degree of freedom systems subjected to a large set of strong ground motion records.In the elastic case, design displacement spectra, modeled in a simplified way with a bilinear shape in the period range 0–4 s, are then proposed for the estimation of the displacement demand to structures located on different local soil condition, at different distance from the causative fault, and for different levels of magnitude. In order to evaluate the reliability of the proposed design displacement spectra, probabilistic displacement spectra corresponding to different levels of probability of non-exceedance were also carried out.The inelastic displacement demand to elasto-plastic systems was analyzed through the ratio between inelastic and elastic spectral displacements. Simplified relationships of the inelastic displacement ratio are then proposed as a function of displacement ductility, soil condition and period of vibration. Finally, as a comparison, the inelastic displacement ratios were also estimated considering other constitutive models.     

去污剂对裙带菜色素-蛋白质复合物电泳分离效果及其性质的影响

于1998年3月在青岛市太平角采集裙带菜孢子体，通过破碎、离心制备类囊体膜，用去污剂SDS、DOC、DMG和DIG增溶裙带菜类囊体膜，经PAGE分离色素-蛋白质复合物，并测定其光谱特性，结果表明，电泳分离效果与所用的去污剂的种类有关。去污剂不同，分离到的同一类型复合物的吸收光谱有差异，捕光色素-蛋白质复合物的数目、种类及吸收光谱明显不同，电泳中产生的游离色素的多少也随去污剂种类而异，在4种去污剂中，以光谱明显不同，电泳中产生的游离色素的多少也随去污剂种类而异，在4种去污剂中，以DMG和DIG增溶的效果最好，经SDS-PAGE分出6种色素-蛋白质复合物，游离色素较少，DMG和DIG增溶的效果最好，经SDS-PAGE分出6种色素-蛋白质复合物，游离色素较少。     

Source parameters and scaling relationships in the Friuli-Venezia Giulia (Northeastern Italy) region

We estimated the source parameters of 53 local earthquakes (2.0<M_L<5.7) of the Friuli-Venezia Giulia (Northeastern Italy) area, recorded by the short-period local seismic network of the Istituto Nazionale di Oceanografia e Geofisica Sperimentale (OGS), in the period 1995-2003. Data were selected on the basis of high quality locations and focal mechanisms. Standard H/V spectral ratios (HVRS) of the three-component stations of the network were performed in order to assess local amplifications, and only stations showing HVRS not exceeding two were considered for the source parameters estimation. Both velocity and acceleration data were used to compute the SH-wave spectra. Observed spectra were corrected for attenuation effects using an independent regional estimate of the quality factor Q and a station dependent estimate of the spectral decay parameter k. Only earthquakes with M_L>3.0 recorded with a sampling rate of 125 cps were used to compute k, thus allowing to visualize a linear trend of the high frequency acceleration spectrum up to 40-50 Hz. SH-wave spectra, corrected for attenuation, showed an ω⁻² shape allowing a good fit with the Brune model. Seismic moments and Brune radii ranged between 1.5×10¹² and 1.1×10¹⁷  N m and between 0.1 and 2.7 km respectively. We obtained M_o=1.1×10¹⁷  N m for the seismic moment of the Kobarid (SLO) main shock, in good agreement with the Harvard CMT solution (M_o=3.5×10¹⁷  N m). Brune stress drops were confined to the range from 0.07 to 5.31 MPa, with an average value of 0.73 MPa and seem to be approximately constant over five orders of magnitude of seismic moment. Radiated seismic energy computed from two nearby stations scales with seismic moment according to , and apparent stress values are between 0.02 and 4.26 MPa. The observed scatter of Brune stress drop data allowed to hypothesize a scaling relation between seismic moment and corner frequency in order to accommodate both Brune stress drop and apparent stress scalings. No systematic differences are evidenced between stress parameters of earthquakes with different focal mechanisms. As a consequence, a relation of the seismic stress release with the strength of rocks can be hypothesized. A high correlation (r>0.9) of Brune stress drop is found with both apparent stress and RMS stress drop, according to and respectively.     

Probabilistic estimation of maximum inelastic displacement demands for performance‐based design

A probabilistic approach to estimate maximum inelastic displacement demands of single‐degree‐of‐freedom (SDOF) systems is presented. By making use of the probability of exceedance of maximum inelastic displacement demands for given maximum elastic spectral displacement and the mean annual frequency of exceedance of elastic spectral ordinates, a simplified procedure is proposed to estimate mean annual frequencies of exceedance of maximum inelastic displacement demands. Simplifying assumptions are thoroughly examined and discussed. Using readily available elastic seismic hazard curves the procedure can be used to compute maximum inelastic displacement seismic hazard curves and uniform hazard spectra of maximum inelastic displacement demands. The resulting maximum inelastic displacement demand spectra provide a more rational way of establishing seismic demands for new and existing structures when performance‐based approaches are used. The proposed procedure is illustrated for elastoplastic SDOF systems having known‐lateral strength located in a region of high seismicity in California. Copyright © 2007 John Wiley & Sons, Ltd.     

硼酸/硼砂与多羟基化合物在水溶液中的反应:pH、电导率、Raman光谱研究

与多羟基化合物络合是去除和分离溶液中微量硼的有效手段,但我们对多羟基化合物与硼酸盐的反应缺乏深入认识。本文通过测定硼酸/硼砂与木糖醇、D-果糖、D-山梨醇和D-甘露醇在水溶液中反应的pH、电导率及Raman光谱,综合对比研究了硼酸/硼砂与四种多羟基化合物的络合反应。对于多羟基化合物/硼酸水溶液,随着多羟基化合物浓度的增加,溶液的pH值降低,电导率显著增加。对于多羟基化合物/硼砂水溶液,随着多羟基化合物浓度的增加,溶液的pH值和电导率都是首先明显降低,之后缓慢降低。为使硼酸/硼砂络合完全,多羟基化合物与硼酸的物质量的比要大于2。四种多羟基化合物与硼酸反应后,都出现了新的Raman峰,D-甘露醇与硼酸在溶液中反应后,在1 207 cm~(-1)处出现了较强的Raman峰。在四种多羟基化合物中,D-甘露醇与硼酸/硼砂的反应效果更好。     

掺稀土萤石:Eu3+的发光性质

利用天然萤石矿物原料经掺杂合成出萤石：Eu^3 荧光体。根据荧光光谱及格位对称性关系，该体系中主要存在两类发光中心，其位置对称分别为C4v和C3v。Eu^3 离子进入CaF3晶格，与Ca^2 离子不等价置换，由于电荷补偿，Eu^3 离子周围常常存在间隙Fi^-的缺陷。间隙Fi^-的存在，降低了局域对称性(由Oh降低为C4v和C3v)，打破了宇称选择定则，有利于Eu^3 离子的发光。另外，当间隙Fi^-为远程补偿时，Eu^3 离子依然占据Oh位置。以^5D0→^7F1允许的磁偶极跃迁为主，但占据此位置的Eu^3 离子数量是非常小的。     

Near‐source seismic hazard and design scenarios

Earthquakes damage engineering structures near, relatively to the rupture's size, to the source. In this region, the fault's dynamics affect ground motion propagation differently from site to site, resulting in systematic spatial variability known as directivity. Although a number of researches recommend that records with directivity‐related velocity pulses should be explicitly taken into account when defining design seismic action on structures, probabilistic seismic hazard analysis (PSHA), in its standard version, seems inadequate for the scope. In the study, it is critically reviewed why, from the structural engineering point of view, hazard assessment should account for near‐source effects (i.e., pulse‐like ground motions), and how this can be carried out adjusting PSHA analytically via introduction of specific terms and empirically calibrated models. Disaggregation analysis and design scenarios for near‐source PSHA are also formulated. The analytical procedures are then applied to develop examples of hazard estimates for sites close to strike–slip or dip–slip faults and to address differences with respect to the ordinary case, that is, when pulse‐like effects are not explicitly accounted for. Significant increase of hazard for selected spectral ordinates is found in all investigated cases; increments depend on the fault‐site configuration. Moreover, to address design scenarios for seismic actions on structures, disaggregation results are also discussed, along with limitations of current design spectra to highlight the pulse‐like effects of structural interest. Finally, an attempt to overcome these, by means of disaggregation‐based scenarios specific for the pulse occurrence case, is presented. Copyright © 2012 John Wiley & Sons, Ltd.     

Spatial distribution of altered minerals in the Gadag Schist Belt (GSB) of Karnataka,Southern India using hyperspectral remote sensing data

Spatial distribution of altered minerals in rocks and soils in the Gadag Schist Belt (GSB) is carried out using Hyperion data of March 2013. The entire spectral range is processed with emphasis on VNIR (0.4–1.0 μm) and SWIR regions (2.0–2.4 μm). Processing methodology includes Fast Line-of-sight Atmospheric Analysis of Spectral Hypercubes correction, minimum noise fraction transformation, spectral feature fitting (SFF) and spectral angle mapper (SAM) in conjunction with spectra collected, using an analytical spectral device spectroradiometer. A total of 155 bands were analysed to identify and map the major altered minerals by studying the absorption bands between the 0.4–1.0-μm and 2.0–2.3-μm wavelength regions. The most important and diagnostic spectral absorption features occur at 0.6–0.7 μm, 0.86 and at 0.9 μm in the VNIR region due to charge transfer of crystal field effect in the transition elements, whereas absorption near 2.1, 2.2, 2.25 and 2.33 μm in the SWIR region is related to the bending and stretching of the bonds in hydrous minerals (Al-OH, Fe-OH and Mg-OH), particularly in clay minerals. SAM and SFF techniques are implemented to identify the minerals present. A score of 0.33–1 was assigned for both SAM and SFF, where a value of 1 indicates the exact mineral type. However, endmember spectra were compared with United States Geological Survey and John Hopkins University spectral libraries for minerals and soils. Five minerals, i.e. kaolinite-5, kaolinite-2, muscovite, haematite, kaosmec and one soil, i.e. greyish brown loam have been identified. Greyish brown loam and kaosmec have been mapped as the major weathering/altered products present in soils and rocks of the GSB. This was followed by haematite and kaolinite. The SAM classifier was then applied on a Hyperion image to produce a mineral map. The dominant lithology of the area included greywacke, argillite and granite gneiss.     

钛闪石在不同浓度盐酸中的溶解作用

对采自澳大利亚Carnperdown钛闪石分别进行了浓度为1,2和3mol/L的盐酸溶解实验,溶解时间分别为：110,170,245,335,455,605,785,995,1235和1505min。浸蚀后的酸液用ICP-AES进行了金属阳离子浓度测定;残余固体则用X射线衍射法和红外吸收光谱进行了研究。实验表明,酸浓度愈大,角闪石阳离子的浸出浓度也愈大。这与一般的硅酸盐矿物的溶解规律相一致。此外,阳离子的溶出量主要受晶体结构制约,连接相邻工字梁的曰位离子优先溶出。致使在溶出液中Ca^2＋浓度与其它八面体阳离子的浓度比大于分子式中的比值。基于对未浸蚀样品和浸蚀后残余固体的X射线衍射和红外吸收谱研究可知,阳离子的溶出并未造成闪石结构中硅氧骨干的变化。