Frequency characteristics of geomagnetic induction anomalies in Saurashtra region     

P V Vijaya Kumar  P B V Subba Rao  C K Rao  A K Singh  P Rama Rao 《Journal of Earth System Science》2017,126(7):101

Magnetovariational studies were carried out along four different EW profiles in Saurashtra region in different phases, during January 2007–March 2012. Transient geomagnetic field variations (X, Y horizontal field and Z vertical field components) recorded along these profiles are analyzed to infer the electrical conductivity distribution of the region. The vertical field transfer functions which depict the characteristics of electrical conductivity distribution are presented in the form of induction arrows. From the spatial distribution of these arrows, it is inferred that the sediments filling the offshore basins have more conductivity than those basins in Saurashtra region. Z/H pseudo sections along the four profiles in conjunction with tectonics and other geophysical methods permit to infer that the conductivity anomaly in the eastern part of the profiles is associated with the crustal/lithosphere thinning. The possible cause for these anomalies may be explained in terms of partial melts associated with mafic intrusions, related to Deccan and pre-Deccan volcanism. High resistive block related to underplating mantle material has been reflected in 1D models of long period magnetotelluric data and its thickness reduces from west to east. Lithosphere–asthenosphere boundary varies from 80 to 100 km.  相似文献   

Enhanced control of activated sludge process using predetermined set-points     

B. Vivekanandan  A. Seshagiri Rao  R. Saravananae 《International Journal of Environmental Science and Technology》2017,14(3):487-496

The performance of activated sludge process (ASP) is evaluated by the effluent quality which is determined by five different variables of the treated wastewater such as ammonia, total nitrogen, COD, BOD₅ and TSS. To keep these five variables within the limits as per environmental regulations, nitrate and nitrite concentration (S _NO) in the second anoxic reactor and the dissolved oxygen concentration (S _O) in the last aerobic reactor of the ASP should be maintained at prescribed levels. To do that, a closed-loop control configuration is required and proper set-points for these closed-loop control configurations are needed. In this paper, the optimal values of controller set-points are determined for nitrogen removal in the activated sludge process. Effluent quality limits have been considered to evaluate the optimal set-points for the Indian climatic conditions. Once the optimal set-points are determined, PI controllers are used to control S _NO in the second anoxic reactor and S _O in the last aerobic reactor of the ASP. Further, feed-forward control is incorporated to minimize the effect of disturbances, which enters along with the influent. No case studies of BSM1 model have been reported in the literature for the Indian wastewater. In this work, the dynamic simulation of an activated sludge process is performed using the data collected from the sewage treatment plant, located in India. The results of the simulation showed that feed-forward with PI control strategy, ASP can be efficiently controlled without any effluent violations, when compared to BSM1.  相似文献   

Distribution and fractionation of rare earth elements and Yttrium in suspended and bottom sediments of the Kali estuary,western India     

S. Suja  Lina L. Fernandes  V. Purnachandra Rao 《Environmental Earth Sciences》2017,76(4):174

Concentrations of rare earth elements (REE) and yttrium (Y), and major metals (Al, Fe and Mn) were measured in suspended particulate matter (SPM) and bottom sediments of the Kali estuary, western India, for their distribution and fractionation. The contents of SPM and metals in it were more uniform along the longitudinal transect during the monsoon. During the post- and pre-monsoons, low SPM in the upper/middle estuary coincided with high Fe and Mn and total REE (∑REE). But in the lower estuary SPM and its ∑REE content increased seaward, while Fe and Mn decreased. The Y/Ho ratios decreased seaward during the monsoon but increased during the post-monsoon. Sm/Nd ratios were more uniform along the transect during monsoon but decreased marginally seaward in other seasons. The Post-Archean Average Australian Shale (PAAS)-normalized REE patterns exhibited middle REE and heavy REE enrichment with positive Ce (\({\text{Ce}}/{\text{Ce}}^{*}\)), Eu (\({\text{Eu}}/{\text{Eu}}^{*}\)) and Y anomalies. The \({\text{Ce}}/{\text{Ce}}^{*}\) increased but \({\text{Eu}}/{\text{Eu}}^{*}\) decreased marginally seaward. The fine-grained sediments showed higher ∑REE and lower Y/Ho ratios than in coarse-grained sediments. The PAAS-normalized REE patterns of sediment were similar to that of SPM. The results revealed two processes, colloidal flocculation and coagulation of metals in the low-salinity zone and an estuarine turbidity maximum in the high salinity zone. Rare earths and yttrium (REY) in SPM and sediments primarily reflected the source rock composition than that of chemical weathering. Apart from physico-chemical processes, the mineralogy and grain size of sediments controlled the distribution and fractionation of REY in the estuary.  相似文献   

Bianchi type-V cosmological model with perfect fluid using negative constant deceleration parameter in a scalar tensor theory based on Lyra Manifold     

V. U. M. Rao  T. Vinutha  M. Vijaya Santhi 《Astrophysics and Space Science》2008,314(1-3):213-216

An exact Bianchi type-V perfect fluid cosmological model is obtained in a scalar tensor theory proposed by Sen (Z. Phys. 149:311, 1957) based on Lyra Manifold in case of β is a constant and it is shown that this cosmological model exists only in the case of Radiation Universe (ρ=3p) if β is a function of ‘t’ using negative constant deceleration parameter. Some physical and geometrical properties of these models are discussed.  相似文献   

一次副热带高压后部层状云降水中山区层状云宏微物理结构探测分析   总被引：1，自引：1，他引：0  

马新成  黄梦宇  于潇洧  金华  毕凯  董鹏捷  张磊  张蔷 《气候与环境研究》2012,17(6):711-718

利用2010年8月18日副热带高压后部层状云降水中山区层状云的飞机穿云观测资料,结合雷达、卫星云图及天气图等资料,详细分析了此次高后降水中山区层状云的宏观特征、微物理结构,并对降水形成机制进行初步探讨.结果表明:此个例由两层云构成,上层为冷云,下层主要为暖云;冷层粒子图像显示主要以板状为主,平板柱状、柱状和霰粒为辅,冰粒子的聚合体在整个冷层都有出现;降水形成机制为播种—喂养机制,冷云中观测到丛集和淞附现象,其中淞附现象主要发生在冷云的中下部靠近融化层附近.  相似文献   

叠合盆地深层构造—热演化研究方法:以四川盆地为例   总被引：1，自引：0，他引：1       下载免费PDF全文

饶松  胡迪  胡圣标  王强  汪集旸 《地质科学》2019,(1):159-175

与简单盆地和叠合盆地中-浅层相比,叠合盆地深层往往缺乏镜质体反射率等传统古温标,海相碳酸盐岩层次往往缺乏磷灰石、锆石等重矿物而无法开展裂变径迹和（U-Th）/He分析,而且经历了多期复杂热史,古温标早期热记录被后期构造-热事件叠加改造,因此单一古温标和单一的热史恢复模式难以满足叠合盆地深层构造-热演化研究。本文从沉积盆地构造-热演化基本研究方法入手,着重介绍了发展迅速的多种显微组分荧光分析（FAMM）和二元同位素技术。针对叠合盆地深层多期复杂热史恢复的难点,以四川盆地为例总结了开展叠合盆地深层构造-热演化研究的思路和工作方法。叠合盆地深层构造-热演化研究应坚持今古地温场并举、盆地热演化与区域构造演化相结合、地质-地球物理-地球化学三位一体的总体工作思路,多温标耦合,正、反演结合,既考虑岩石圈热演化的动力学规律,又考虑该演化过程对盆地基底沉降、地层发育、古温标热演化程度的影响,只有这样才能保证叠合盆地深层构造-热演化研究结果的可靠性。  相似文献   

贵德盆地三河流域高砷地下水中溶解性有机物三维荧光特性及其指示意义   总被引：1，自引：0，他引：1  

梁梦钰  郭华明  李晓萌  王振  修伟 《地学前缘》2019,26(3):243-254

溶解性有机物(dissolved organic matter, DOM)可以通过多种方式控制含水层中砷的迁移转化。贵德盆地承压含水层地下水砷含量显著高于潜水含水层。为查明承压水中溶解性有机物对砷浓度的影响,对研究区地表水、潜水以及承压水进行吸光度和三维荧光光谱的分析,利用平行因子分析法确定了水样中有机物成分及荧光特征。结果表明,贵德盆地水体中DOM包含陆源类腐殖质(C1)、受人为影响的腐殖质(C2)、类醌化合物(C3)和微生物来源的腐殖质(C4)4种组分。陆源类腐殖质C1可在地下水中富集,占总有机质的40%~55%。相比于地下水,C2和C3则在地表水中占据较高的比例。高砷承压水中C2、C3所占比例高于低砷潜水。其中,C1可以通过络合作用促进溶解性砷浓度的提高,C3作为电子穿梭体可以促进含砷铁氧化物或氢氧化物的还原性溶解从而释放砷。微生物降解有机质生成的HCO-3可以与砷竞争吸附,促进砷的解吸附。此外,还原性溶解产生的Fe(II)与HCO-3形成FeCO3固定一部分的砷。该研究表明,地下水中的天然有机物通过络合作用和作为电子穿梭体促进铁氧化物还原导致地下水砷的富集,为分析黄河上游地区高砷地下水的成因提供理论依据。  相似文献   

High resolution spectroscopy of R Coronae Borealis during the 1988— 1989 minimum     

David L. Lambert  N. Kameswara Rao  Sunetra Giridhar 《Journal of Astrophysics and Astronomy》1990,11(4):475-490

Moderate-resolution spectra of the C₂ Swan 0-1 bandhead, the Na I D lines and the K_I resonance lines near 7660 Å obtained at minimum light during the 1988–1989 decline of R CrB are discussed and interpreted in terms of a popular model for R CrB declines. High-resolution spectra obtained at maximum light show blue-shifted chromospheric emission in the cores of the Na I D and the Sc π 4246.8 Å lines  相似文献   

Bianchi type-II cosmological models in the presence of zero-mass scalar fields     

K. Shanthi  V. U. M. Rao 《Astrophysics and Space Science》1990,172(1):77-81

The exact Bianchi type-II vacuum- and stiff-fluid cosmological models, in the presence of zero-mass scalar fields, are obtained. Some physical properties of the models are also discussed.  相似文献   

P-wave seismograms from continuously varying transition zones—II. Elastic media     

M. A. A. Goda  C. R. A. Rao 《Geophysical Journal International》1978,52(1):183-200

Summary. A class of elastic transition zones are modelled by considering a homogeneous half space overlying an inhomogeneous half space with a bounded and monotonically increasing profile for the rigidity modulus and constant Poisson's ratio and density. Reflected P waves due to a compressional point source in the upper half space are studied in the frequency and time domains by means of numerical contour integration in the complex k plane and the Fast Fourier Transform (FFT). Results from the exact fourth-order elasticity theory are compared with those from the approximate decoupled equations for P and SV waves. Agreement is observed between the two theories at high frequencies beyond the caustic range.  相似文献