Inverse modelling for parameter estimation and experiment design

Inverse modelling forced itself on the attention of scientists in the 1960s with the advent of satellites and other revelatory technologies, despite their putative ill-posedness, when it became clear that estimation of parameters of a system not in themselves directly observed but extractable from their signatures in measured data, constituted an ineluctable problem of modern society. This paper begins by formulating the basic statement of inverse problems which have a generic form and leads through philosophical and analytical approaches to their possible solutions that are inherently non-unique. Finally, an example is provided for inverse modelling of the shear wave velocity structure of the crust beneath the ancient granites around Hyderabad from an analysis of reverberations caused by it that appear in the early part of broadband seismograms

A gene producing one to nine flowers per flowering node in chickpea

Chickpea (Cicer arietinum L.) has a racemose type of inflorescence and at each axis of the raceme usually one or two and rarely three flowers are borne. Plants producing 3 to 9 flowers, arranged in a cymose inflorescence, at many axis of the raceme, were identified in F2 of an interspecific cross ICC 5783 (C. arietinum) × ICCW 9 (C. reticulatum) in which both the parents involved were single-flowered. A spontaneous mutation in one of the two parents or in the F1 was suspected. However, the possibility for establishment of a rare recombination of two interacting recessive genes could not be ruled out. The number of pods set varied from 0 to 5 in each cyme. Inheritance studies indicated that a single recessive gene, designated cym, is responsible for cymose inflorescence. The allelic relationship of cym with sfl, a gene for double-flowered trait, was studied from a cross involving multiflowered plants and the double-flowered line ICC 4929. The cym gene was not allelic to sfl, suggesting that two loci control the number of flowers per peduncle in chickpea. The cym locus segregated independently of the locus sfl, ifc (inhibitor of flower color) and blv (bronze leave)

Receding the entrainment of concomitant Ultrafines by MGS in Lead Concentrate of Rajpura - Dariba Concentrator

Due to the fine dissemination and complex mineralogy the Rajpu ra-Dariba (RD) lead --inc ore poses special problems in concentration by corrventional froth flotation. In order to achieve the desired metallurgical results 'Multi Gravity Separator, a twin drum system, has recently been installed in the lead circuit of RD concentrator. Open and closed trial tests were conducted, without sacrificing the economic metal tt•ith substantial abatement of ultrafine card fine srliceuus and graphite matter in lead concentrate. The metallurgical alludes achieved are (i) over 85% -400 mesh fines are separated in the form of MGS tails whereas 53% -400 mesh are obtained in MGS concentrate from the feed(lead rougher concentrate) 77% -400 mesh with 52% Pb, I% Gr. C and 2.5% ISM in respective Wt. %distribution i.e., 47.3 and 3, (ii) tails are characterised br- >93% ultrafine of <20 microns particles encompass 21 % Pb, 8% Gr: C and 39% ISM with respective Wt. % distribution i.e., 32. 93, 83% in -400 mesh fr-action, resulting in effective rejection of Gr. C and ISM, (iii)conventional lead concentrate consists of 28% +400 mesh material only with all the assorted fines and ultrafines. Mine ralogically, it is established that composite bigger particles of sulphide gangue and graphite are the main contributor. for silica and graphite in MGS concentrate. Over 39% by vol. fines are alienated as MGS tails, in the form of free sulphide, gangue and graphite minerals. Installation of MGS in lead circuit, confirms the significant reduction of Gr:C and ISM in particular to high GMS_feed rnix in lead concentrate in comparison to lead concentrate by conventional route

Frequency-dependent Lg attenuation in the Indian Platform

We use seismograms from regional earthquakes recorded on digital seismographs in peninsular India to determine the frequency-dependent Q of Lg for the Indian platform. We measure Lg attenuation by determining the decay of spectral amplitudes with distance. The available data suggest some spatial variation in attenuation but a much denser ray-path coverage would be required to validate such observations. We, therefore, combine all the measurements of overlapping regions that span both the shield and intervening terranes to obtain an average value of attenuation for the Indian platform: Lg–Q = 665 ± 10 with the frequency exponent n = 0.67 ± 0.03. This average value of Lg attenuation for the Indian platform is similar to the average for other stable regions of the globe

Variation of rayleigh wave group velocity dispersion and seismic heterogeneity of the Indian crust and uppermost mantle

We present group velocity dispersion results from a study of regional fundamental mode Rayleigh waves propagating across the Indian region. 1-D, path-averaged dispersion measurements have been made for 1001 source-receiver paths and these combined to produce tomographic images between 15 and 45 s period. Because of the dense station coverage in peninsular India, these images have substantially higher lateral resolution for this region than is currently available from global and regional group velocity studies. Testing of the group velocity model shows that the average resolution across the region is about 7.5° for the periods used in this study. The tomographic maps demonstrate that while the Indian shield is characterized by high crustal and uppermost-mantle group velocities, comparatively lower velocities exist beneath the Himalaya due to the thickened crust and beneath the Gangetic plains caused by the mollasse sediments and recent alluvium cover in the Himalayan foredeep. Northeastern India north of the Shillong Plateau also displays higher velocities, similar to the south Indian shield, indicative of colder crust beneath the region. The northern Bay of Bengal shows extremely low velocities due to the thick sediment blanket of the Bengal fan. Likewise, the Katawaz Basin in southern Pakistan shows lower velocities that resemble those seen in the Bay of Bengal. The geometry of the velocity contours south of the Katawaz Basin closely matches the prograding Indus fan in the Arabian Sea. Finally, the Tibetan Plateau has lower group velocities compared to the Indian shield at all periods as a result of the thick crust beneath southern Tibet

On self-similarity of premonitory patterns in the regions of natural and induced seismicity

Anticipating the scale invariance of rock fracturing processes, we applied Keilis-Borok's algorithm M8, originally designed for identifying times of increased probability (TIPS) of occurrence of strong earthquakes (M &lt; 8.0), retrospectively to Koyna earthquakes which occurred in the region after the impoundment of the Shivaji Sagar reservoir in 1962. The algorithm which enables diagnosis of TIPS from the 7th year onwards after the commencement of the earliest available data set showed that the 5.3 magnitude earthquake of 20 September 1980 indeed occurred within a time of increased probability. This result, apart from its potential application to recognizing future TIPS in the region, points to selfsimilarity between the premonitory patterns of natural and induced earthquakes and to scale-invariant nature of their processes. Further, a typical precursory rise in seismicity followed by a relative quiescence was also found to precede all the three larger earthquakes of the sequence

Iron meteorite fall at Bhuka village, Barmer District, Rajasthan

This article does not have an abstract

Complex shallow mantle beneath the Dharwar craton inferred from Rayleigh wave inversion Geophysical Journal International

The 3-D shear velocity structure beneath South India's Dharwar Craton determined from fundamental mode Rayleigh waves phase velocities reveals the existence of anomalously high velocity materials in the depth range of 50–100 km. Tomographic analysis of seismograms recorded on a network of 35 broad-band seismographs shows the uppermost mantle shear wave speeds to be as high as 4.9 km s–1 in the northwestern Dharwar Craton, decreasing both towards the south and the east. Below ∼100 km, the shear wave speed beneath the Dharwar Craton is close to the global average shear wave speed at these depths. Limitations of usable Rayleigh phase periods, however, have restricted the analysis to depths of 120 km, precluding the delineation of the lithosphere–asthenosphere boundary in this region. However, pressure–temperature analysis of xenoliths in the region suggests a lithospheric thickness of at least ∼185 km during the mid-Proterozoic period. The investigations were motivated by a search for seismic indicators in the shallow mantle beneath the distinctly different parts of the Dharwar Craton otherwise distinguished by their lithologies, ages and crustal structure. Since the ages of cratonic crust and of the associated mantle lithosphere around the globe have been found to be broadly similar and their compositions bimodal in time, any distinguishing features of the various parts of the Dharwar shallow mantle could thus shed light on the craton formation process responsible for stabilizing the craton during the Meso- and Neo-Archean