Browsing by Author "Sajid Ali"

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Confidence intervals of the index Cpk for normally distributed quality characteristics using classical and Bayesian methods of estimation
(Brazilian Statistical Association, 2021) Mahendra Saha; Sanku Dey; Abhimanyu Singh Yadav; Sajid Ali
One of the indicators for evaluating the capability of a process potential and performance in an effective way is the process capability index (PCI). It is of great significance to quality control engineers as it quantifies the relation between the actual performance of the process and the pre-set specifications of the product. Most of the traditional PCIs performed well when process follows the normal behaviour. In this article, we consider a process capability index, Cpk, suggested by Kane (Journal of Quality Technology 18 (1986) 41-52) which can be used for normal random variables. The objective of this article is three fold: First, we address different methods of estimation of the process capability index Cpk from frequentist approaches for the normal distribution. We briefly describe different frequentist approaches, namely, maximum likelihood estimators, least squares and weighted least squares estimators, maximum product of spacings estimators, Cramèr-von-Mises estimators, Anderson-Darling estimators and Right- Tail Anderson-Darling estimators and compare them in terms of their mean squared errors using extensive numerical simulations. Second, we compare three parametric bootstrap confidence intervals (BCIs) namely, standard bootstrap, percentile bootstrap and bias-corrected percentile bootstrap. Third, we consider Bayesian estimation under squared error loss function using normal prior for location parameter and inverse gamma for scale parameter for the considered model. Monte Carlo simulation study has been carried out to compare the performances of the classical BCIs and highest posterior density (HPD) credible intervals of Cpk in terms of average widths and coverage probabilities. Finally, two real data sets have been analyzed for illustrative purposes. © Brazilian Statistical Association, 2021.
COUPLED ROLE OF CLIMATE AND TECTONICS IN THE DEPOSITION OF THE LATE QUATERNARY SEDIMENTARY SEQUENCE IN THE SOUTHERN MARGIN OF THE CENTRAL GANGA PLAIN, INDIA
(SEPM Society for Sedimentary Geology, 2024) Mukesh Yadav; U.K. Shukla; G.P. Gurumurthy; Sajid Ali; Kamlesh Kumar; Anupam Sharma
The Ganga Plain’s sedimentation is primarily controlled by Himalayan tectonics, variations in monsoon intensity, and glacier size. However, the significance of intrabasinal tectonics, which is an interplay of the Himalaya tectonics and basement tectonic configuration of the Ganga Plain, in comprehending the late Quaternary Ganga Plain sedimentation remains unclear. In this study, the sediment provenance and extent of weathering experienced by the sediments are studied using the mineralogical and geochemical (major, trace, and rare earth elements) composition of a sedimentary cliff sequence exposed at the Ramnagar locality near the cratonic peripheral bulge in the southern Ganga Plain. In the Ramnagar cliff sediment section, two sediment packages, designated SP-A and SP-B, are identified based on mineralogy, texture, and geochemistry. These packages of sediments show mild chemical weathering and distinct geochemical compositions. The lower part (SP-A) of the Ramnagar cliff section is characterized by higher contributions from mafic sources (pyroxene, feldspar, and mica as dominant minerals), while the upper part (SP-B) is predominately derived from felsic sources (mica and feldspar as dominant minerals), which are supplied via the peninsular and the Himalayan rivers, respectively. The southern part of the central Ganga Plain shows evidence of a shift in the sediment provenance from mafic to felsic source rock at 40 ka. This study demonstrates how weathering and sedimentation are controlled by both regional tectonics and climate in the southern margin of the central Ganga Plain.; The Director of the BSIP, Lucknow, is thanked by the authors for providing all infrastructural (SAIF) and administrative support to complete the assignment. This work is a part of MY’s doctoral thesis, supported by the funding received from the University Grants Commission (CSIR-UGC JRF fellowship, Roll No. 207693) and recorded as BSIP/RDCC/Publication no. 24/2024-25. The authors also thank Dr. Sheikh Nawaz Ali, Dr. Arvind Kumar Singh, Dr. Naimisha Vanik, Harshita Srivastava, Dr. Masud Kawsar, and Dr. Abhisek Kumar for their constructive suggestions that helped to make the manuscript better. UKS is thankful to the Head of the Department of Geology for providing the working facilities of the Department. We thank editor Dr. Kathleen Marsaglia, Associate Editor Dr. Alberto Resentini, and anonymous reviewers for constructive comments on our manuscript. Ó 2024, SEPM (Society for Sedimentary Geology)
Provenance, weathering, and paleoclimatic records of the Pliocene-Pleistocene sequences of the Himalayan foreland basin, NW Himalaya
(Springer Science and Business Media Deutschland GmbH, 2021) Sajid Ali; Binita Phartiyal; Ajay Taloor; Mohammad Arif; Birendra Pratap Singh
We present major oxides, trace element compositions, rare earth elements (REEs), clay mineral assemblages, and magnetic mineral parameters data for the siliciclastic fraction from the Upper Siwalik Subgroup (Parmandal, Nagrota, and Boulder Conglomerate formations) in the Tawi sub-basin of the Himalayan foreland basin, NW Himalaya in order to identify source rock compositions, continental weathering, and paleoclimate over the past 5.6 million years. The trace elemental ratios of Th/Co, Th/Sc, La/Sc, and Cr/Th suggest Upper Siwalik Subgroup sediments initially originated from a stable felsic source, which is possibly in the High Himalayan crystalline and Lesser Himalayan source regions. The REE patterns of the studied sediments with prominent negative Eu anomalies also suggest a felsic source for the Upper Siwalik Subgroup sediments deposited in the basin. The chemical index of alteration (CIA), plagioclase index of alteration (PIA), Rb/Sr ratio, and clay mineral assemblages as well as mineral magnetic parameters demonstrate the variable intensity of weathering and environmental conditions during the deposition of Parmandal, Nagrota, and Boulder Conglomerate formations between 5.6 and 0.6 Ma. The weathering proxy records of Parmandal (5.6 to 3.9 Ma) and Boulder Conglomerate (1.7 to 0.2 Ma) formations indicate relatively strong chemical weathering associated with the warm and wet climates in the source region. On the other hand, a decrease in chemical weathering intensity and change in environmental conditions during the formation of Nagrota formation (3.9–1.7 Ma) suggest a dry and cold climate in the source region. © 2021, Saudi Society for Geosciences.