R.N. Iyengar - Profile on Academia.edu (original) (raw)

Papers by R.N. Iyengar

The first theoretical system of tracking sun in the tropical annual cycle is cryptically mentione... more The first theoretical system of tracking sun in the tropical annual cycle is cryptically mentioned in the Maitrāyaṇīya Āraṇyaka Upaniṣat (MAU) of the Kṛṣṇa Yajurveda, as the southern sojourn of sun starting at the summer solstice. This is called maghādyaṁ, the first point of the maghā nakṣatra, identified most likely with the early morning visibility of ε-Leo, near the azimuth of the sunrise point on the horizon as observed at Kurukshetra. Twenty seven equal nakṣatra sectors named in the traditional sequential order cover one tropical circuit of sun of 366 days with the winter solstice falling exactly at the middle of the śraviṣṭhā sector. Even though MAU mentions each nakṣatra to be made up of four quarters, no practical application of this ¼-nakṣatra sky part amounting to 3º20´ in longitude is seen in Vedic texts till we come to the Brahmāṇḍa Purāṇa, a text closer to the Vedas. This Purāṇa states, observed equinoctial full moon positions corresponding to spring equinox at ¼-kṛttikā and autumn equinox at ¾-viśākha exactly 180º apart as they should be. This statement is analysed in this paper by computer simulation of full moon time series for the years -2400 to -800 to show that the Purāṇa data would be realistically valid for the period 1980 BCE to 1610 BCE. It is further demonstrated that the Purāṇa has followed the maghādi system of solar nakṣatra system stated in the MAU. The central epoch circa 1800 BCE of this maghādi equal nakṣatra solar zodiac got modified, due to precession effects, to the śraviṣṭhādi scheme of Parāśara, Vṛddha Garga and Lagadha dateable to circa 1300 BCE.

Indian Journal of History of Science, 2021

Vṛddha-Gārgiya-Jyotiṣa (VGJ) is an important text of Indian astral sciences before the astronomy ... more Vṛddha-Gārgiya-Jyotiṣa (VGJ) is an important text of Indian astral sciences before the astronomy texts of the Common Era. Only a few of the chapters of this text have been edited and published so far. The present paper reports an important study of two sections of this text which describe the transit of Sun along the 27 asterisms (nakṣatra) during the six seasons beginning with winter. The fi rst section called Ādityacāra describes each season to be covered by Sun travelling 4½ asterisms starting from śraviṣṭhā nakṣatra at the beginning of śiśira ṛtu reckoned as the winter solstice day. The seasons are stated in terms of Sun transiting the beginning, middle and end of nine asterisms some of which are made of more than one star. The second section of the text known as Ṛtusvabhāva starts with the vasanta ṛtu and names twelve asterisms through which Sun transits in the 12 months of the tropical year. It is shown that the solar transit information in the Ādityacāra and the Ṛtusvabhāva chapters of VGJ can be dated, for minimum observational error, to c 1300 BCE and c 500 BCE respectively.

Indian J History of Science, 2023

The first theoretical system of tracking sun in the tropical annual cycle is cryptically mentione... more The first theoretical system of tracking sun in the tropical annual cycle is cryptically mentioned in the Maitrāyaṇīya Āraṇyaka Upaniṣat (MAU) of the Kṛṣṇa Yajurveda, as the southern sojourn of sun starting at the summer solstice. This is called maghādyaṁ, the first point of the maghā nakṣatra, identified most likely with the early morning visibility of ε-Leo, near the azimuth of the sunrise point on the horizon as observed at Kurukshetra. Twenty seven equal nakṣatra sectors named in the traditional sequential order cover one tropical circuit of sun of 366 days with the winter solstice falling exactly at the middle of the śraviṣṭhā sector. Even though MAU mentions each nakṣatra to be made up of four quarters, no practical application of this ¼-nakṣatra sky part amounting to 3º20´ in longitude is seen in Vedic texts till we come to the Brahmāṇḍa Purāṇa, a text closer to the Vedas. This Purāṇa states, observed equinoctial full moon positions corresponding to spring equinox at ¼-kṛttikā and autumn equinox at ¾-viśākha exactly 180º apart as they should be. This statement is analysed in this paper by computer simulation of full moon time series for the years − 2400 to − 800 to show that the Purāṇa data would be realistically valid for the period 1980 BCE to 1610 BCE. It is further demonstrated that the Purāṇa has followed the maghādi system of solar nakṣatra system stated in the MAU. The central epoch circa 1800 BCE of this maghādi equal nakṣatra solar zodiac got modified, due to precession effects, to the śraviṣṭhādi scheme of Parāśara, Vṛddha Garga and Lagadha dateable to circa 1300 BCE.

Estimation of damping in railway vehicles under running conditions

Railway vehicles can be modelled quite accurately as MDOF systems..... The present study is aimed... more Railway vehicles can be modelled quite accurately as MDOF systems..... The present study is aimed at finding the damping of the CRT wagons in the Indian Railways.

Random vibration analysis of stochastic time-varying systems

Journal of Sound and Vibration, 1976

ABSTRACT

Random vibration of a galloping oscillator in wind

महस्विनी January-June 2023, 2023

Shodhasamhita, J. Kavikulaguru Kalidasa Sanskrit University, 2023

This paper brings to light for the first time, the existence of a hither to unknown Vāstuvidyā te... more This paper brings to light for the first time, the existence of a hither to unknown Vāstuvidyā text by Garga, who is one among the eighteen ancient teachers of the subject of Vastuśāstra mentioned in the Matsyapurāṇa. Two manuscripts, one in Newari-Bujinmol script and the other in Devanāgarī, of Vṛddhagarga Vāstuvidyā are available in the National Archives of Nepal. The text in 34 chapters, comprising of more than nine hundred verses, as seen from the style, content, and inclusion of only nakṣatra, tithi, muhūrta for deciding auspiciousness of time, must have originated Before Common Era. The text claims to be on Vāstuvidya as expounded by Vṛddhgarga to his son Kroṣṭuki and other disciples. True to this claim, the text touches on several aspects of site selection, town planning, lay out of palace complex, elephant and horse stables and many other topics, with quantified suggestions for important dimensions. The architectural and construction practices described correspond to wood as the primary material. As of now, this text is the oldest available work in Sanskrit wholly devoted to Vāstuvidyā, covering almost all aspects of architectural engineering that was prevalent in ancient India around 500 BCE.

Spectrum compatible nonstationary earthquake model

“Seismic Hazards in India” in “Exploration and Research for Atomic Minerals” 2014 October, V. 24 and published by Atomic Minerals Directorate for Exploration and Research, Hyderabad, India

Journal of Applied Geochemistry, 2016

Vedic literature refers to a place or region by name Irina. In the Rgveda it appears as a locale ... more Vedic literature refers to a place or region by name Irina. In the Rgveda it appears as a locale frequented by a particular wild animal for drinking water. But with the passage of time, in the Yajurveda texts, the word acquires a negative meaning as a desert or a place devoid of water. Gradually, in the ritualistic Vedic texts Irina gets more and more associated with disaster or misfortune. The physical features associated with Irina, as described metaphorically in the Vedic texts, are analysed to identify its probable location. It is possible the word Irina is the progenitor of the Greek name (gulf of) Eirinon of Periplus which is presently designated as the Ran-of-Kutch. During the Rgveda period Irina was in all probability, situated a little north of the Ran-of-Kutch. Available data indicates its location in the Luni-Jawai plains west of the Aravallis, in Rajasthan. The small town Erinpura (25 degrees 5'N, 73 degrees 3'E) appears to retain memories of the Vedic Irina.

Indian Journal of History of Science, 2004

Closure of "Random Field Modeling of Railway Track Irregularities

Journal of Transportation Engineering-asce, 1997

International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts, 1994

Tattwadipah, 2021

This part presents the Karaṇa-karmaguṇa and the muhūrta karmaguṇa Chapters of VGJ. With this the... more This part presents the Karaṇa-karmaguṇa and the muhūrta karmaguṇa
Chapters of VGJ. With this the First Section or Anga of VGJ is completed. Before Common Era the seven weekdays were not prevalent in India. The manuscripts of VGS carry a chapter called 'graha-karmaguna' giving the seven week days as per the current practice. This has been included here as an appendix. Since this is not mentioned in the original contents of VGJ in its second chpater, we treat this 'graha/Varakarmaguna' as a later addition.

The views expressed in the articles published in this journal are not necessarily the views of th... more The views expressed in the articles published in this journal are not necessarily the views of the Institute.

Empirical random process models, based only on past data, are in vogue for simulating strong moti... more Empirical random process models, based only on past data, are in vogue for simulating strong motion accelerograms. These are used to evaluate the safety of important structures like large dams and nuclear power plants. However, to make the results more rational one has to incorporate source mechanics into these models. The acceptability of such results depends on how realistically the source zone, several kilometers below the surface, can be modeled. The source zone of a strong earthquake can be mapped indirectly, if several reliable surface level strong motion records are available for an earthquake event. Since earthquakes are rare, such data does not accrue fast, making data acquisition costly. This is all the more a reason why available data should be put to optimal use to understand the type of ground motion that may arise in future. With this in view, several ensembles of past strong motion records have been analyzed in this paper to identify and map the causative zone of the corresponding events. The region encompassing the strong motion accelerograph (SMA) array is modeled as a layered elastic half space with known properties. The source is represented as a sequence of double couples evolving as ramp functions, triggering at different instants, distributed in a region yet to be mapped. The known surface level ground motion time histories are treated as responses to the unknown double couples on the fault surface. The location, orientation, magnitude and rise time of the double couples are found by minimizing the mean square error between the analytical and recorded solutions. Suitable constraints are used to arrive at physically meaningful solutions. Numerical results are presented for San Fernando, Imperial Valley, Uttarakashi, and Chi-Chi earthquakes. Results obtained are in good agreement with those obtained from other approaches.

Indian Journal of History of Science, 2018

Indian classical music also known as rāga music traces its origin to the style of chanting hymns ... more Indian classical music also known as rāga music traces its origin to the style of chanting hymns of the Sāmaveda (2 nd-3 rd Millennium BCE) that is in practice to this day. The transition from the sacred to secular or worldly music is textually evidenced for the first time in the Nāya-śāstra of Bharata (100 BCE-100CE). All texts attest to the fact that the string instrument generically called Vīā, that is in use since Vedic times is indispensable in understanding the subtle nuances of the theory behind Hindu classical music. The present paper reviews some of the well-known texts from a historical perspective to bring out several scientific aspects studied or expounded by our ancient authors regarding technical terms such as śruti, svara, dvigua and rāga that form the foundation of the theory. It is demonstrated that the theory and practice of rāga music is based on the probabilistic concept alpatva-bahutva, first enunciated by Bharata and elaborated later by Dattila, Mataga, Śārgadeva among others.

It is shown that time series data of monsoon seasonal rainfall at subdivision level is decomposab... more It is shown that time series data of monsoon seasonal rainfall at subdivision level is decomposable into six uncorrelated components. These narrowband processes called intrinsic mode functions, in decreasing order of importance, reflect the influence of ENSO, sunspot activity and tidal cycle on inter annual rainfall variability. The decomposition helps in proposing a statistical method to forecast monsoon rainfall in the three subdivisions of Karnataka.