Aditya Varma - Academia.edu (original) (raw)
Papers by Aditya Varma
Physics of the Earth and Planetary Interiors
The preference for the axial dipole in planetary dynamos is investigated through the analysis of ... more The preference for the axial dipole in planetary dynamos is investigated through the analysis of wave motions in spherical dynamo models. Our study focuses on the role of slow magnetostrophic waves, which are generated from localized balances between the Lorentz, Coriolis and buoyancy (MAC) forces. Since the slow waves are known to intensify with increasing field strength, simulations in which the field grows from a small seed towards saturation are useful in understanding the role of these waves in dynamo action. Axial group velocity measurements in the energy-containing scales show that fast inertial waves slightly modified by the magnetic field and buoyancy are dominant under weak fields. However, the dominance of the slow waves is evident for strong fields satisfying |ω M /ω C | ∼ 0.1, where ω M and ω C are the frequencies of the Alfvén and inertial waves respectively. A MAC wave window of azimuthal wavenumbers is identified wherein helicity generation by the slow waves strongly correlates with dipole generation. Analysis of the magnetic induction equation suggests a poloidal-poloidal field conversion in the formation of the dipole. Finally, the attenuation of slow waves may result in polarity reversals in a strongly driven Earth's core.
2022 8th International Conference on Advanced Computing and Communication Systems (ICACCS)
IP Indian Journal of Anatomy and Surgery of Head, Neck and Brain, 2022
The incidence of venous aneurysm is less than the arterial aneurysms. The knowledge of Popliteal ... more The incidence of venous aneurysm is less than the arterial aneurysms. The knowledge of Popliteal vein aneurysm (PVA) is important as it could be a source of pulmonary embolism, deep vein thrombosis and so could be fatal. PVA could be an incidental finding during the investigations for pulmonary embolism or chronic venous insufficiency. We report a case of left popliteal vein aneurysm in the popliteal fossa in a 65-year-old female cadaver observed during routine dissection. A large saccular dilatation was noted in the left popliteal vein in the distal part of the popliteal fossa. The right popliteal vein was normal.An early diagnosis of PVA with doppler ultrasound examination is important to prevent the occurrence of any thromboembolic events or other major complications.
2017 International Conference on Inventive Computing and Informatics (ICICI), 2017
The Transmission Control Protocol forms the backbone of data communication networks the world ove... more The Transmission Control Protocol forms the backbone of data communication networks the world over. While TCP congestion control protocols operate efficiently over wired networks, their performance in wireless networks leaves a great deal to be desired. Wireless networks are prone to random packet drops for a myriad of reasons apart from network congestion, such as poor channel characteristics, high BER, the hidden node problem and the number of hops between source and destination. This paper aims to perform a comparison of the congestion control schemes of two TCP variants: Reno and New Reno, in a wireless mesh network and analyze the throughput, propagation delay, number of segments retransmitted and number of duplicate acknowledgements received for four different node densities. The behaviour of TCP in wireless networks is observed and plausible justifications attempted. Overall, TCP New Reno shows 40% higher throughput and 25% lower delay as compared to TCP Reno.
Poster: "RANZCR ASM 2010 / R-0135 / RADIOGUIDED OCCULT LESION LOCALIZATION (ROLL) COMBINED W... more Poster: "RANZCR ASM 2010 / R-0135 / RADIOGUIDED OCCULT LESION LOCALIZATION (ROLL) COMBINED WITH WIRE GUIDED LOCALIZATION (WGL) FOR SURGICAL EXCISION OF NONPALPABLE BREAST LESIONS" by: "A. Varma, A. G. M. M. Bourke, M. Brookes, A. Yeo; WA/AU"
Poster: "2016 ASM / R-0057 / MRI of Perianal Fistulas in Crohn's Disease" by: "... more Poster: "2016 ASM / R-0057 / MRI of Perianal Fistulas in Crohn's Disease" by: "W. C. Tsai, A. Varma; TAS/AU"
International Journal of Reproduction, Contraception, Obstetrics and Gynecology, 2022
Background: The aim was to determine whether oral route of maternal hydration was advantageous ov... more Background: The aim was to determine whether oral route of maternal hydration was advantageous over intravenous route in terms of increasing AFI and improving maternal and perinatal outcome in women having borderline oligohydramnios.Methods: At Aarogya hospital, 150 women in third trimester with borderline oligohydramnios (BO) AFI 5.1-8 cm, were divided randomly into two groups, oral hydration group (OG) and intravenous hydration (IVG). Each case was studied on OPD basis. After 2 hours, 48 hours and 1 week of oral or IV hydration. AFI was reassessed by same sonographer. Pre-delivery AFI and various outcome measures were recorded for both groups.Results: There was an increase in AFI by 44.5% in OG from 0 hour till delivery as compared to 30.7% increase in IVG. MSL occurred in 8 (10.7%) women in OG compared to 17 (22.6%) in IVG. FD was found in 4 (5.3%) in OG requiring LSCS compared to 16 (21.3%) in IVG. Total of 59 (78.7%) patients in OG has spontaneous vaginal delivery as compared t...
Poster: "2018 ASM / R-0068 / 3D PRINTING: Hope or Hype" by: "A. Varma, R. Olivotto... more Poster: "2018 ASM / R-0068 / 3D PRINTING: Hope or Hype" by: "A. Varma, R. Olivotto, A. Hodgkinson; QLD/AU"
2017 International Conference on Intelligent Computing, Instrumentation and Control Technologies (ICICICT), 2017
TCP is the standard transport protocol for reliable data communication over the internet. However... more TCP is the standard transport protocol for reliable data communication over the internet. However, TCP behaviour over wireless mesh networks encounters random losses due to channel errors, changing topology and node distance. This paper aims to perform a comparison of TCP Old Tahoe and Tahoe in wireless mesh networks and analyze the throughput, propagation delay, packets retransmitted and number of duplicate acknowledgements received for varying node densities. The anomalous behaviour of TCP in the wireless network is documented, and probable explanations are provided. A comparison of the most suitable variant for each case is concluded. Overall, Tahoe shows 52% lower average throughput and 14% lower delay as compared to Old Tahoe. TCP Old Tahoe appears to be more suitable for lower density networks, whereas TCP Tahoe gives better results for higher density networks.
ArXiv, 2020
In this paper, with a view toward fast deployment of locomotion gaits in low-cost hardware, we us... more In this paper, with a view toward fast deployment of locomotion gaits in low-cost hardware, we use a linear policy for realizing end-foot trajectories in the quadruped robot, Stoch 222. In particular, the parameters of the end-foot trajectories are shaped via a linear feedback policy that takes the torso orientation and the terrain slope as inputs. The corresponding desired joint angles are obtained via an inverse kinematics solver and tracked via a PID control law. Augmented Random Search, a model-free and a gradient-free learning algorithm is used to train this linear policy. Simulation results show that the resulting walking is robust to external pushes and terrain slope variations. This methodology is not only computationally light-weight but also uses minimal sensing and actuation capabilities in the robot, thereby justifying the approach.
Poster: "2016 ASM / R-0058 / Causes of the non-surgical acute abdomen - a pictorial essay&qu... more Poster: "2016 ASM / R-0058 / Causes of the non-surgical acute abdomen - a pictorial essay" by: "W. C. Tsai, A. Varma; TAS/AU"
This paper explores multi-decade tensions in Indo-American relations, emphasizing the formative n... more This paper explores multi-decade tensions in Indo-American relations, emphasizing the formative nature of the colonial legacy on India’s foreign policy and resulting conflict with the Truman Doctrine. By examining the popular perception of foreign policy through political leaders, newspapers, ideological conflicts and State Department records, I illustrate how each nation’s sovereign agenda colored their reception of the other’s global initiatives. The year 1947 marked a point of departure in American foreign policy in two respects; a renewed commitment to economic and military engagement with global affairs under the presidency of Harry Truman, and an expanded interest in diplomacy with developing nations, such as the Republic of India. Contrary to expectations, the promising beginnings of 1947 found no realization amid accelerating hostilities, ultimately leading to the Indo-Soviet Friendship Treaty of 1971. This paper analyzes this understudied period in Indo-American relations –...
2017 International Conference on Inventive Computing and Informatics (ICICI), 2017
With the ever growing global population, crowding in public transport is becoming an increasing m... more With the ever growing global population, crowding in public transport is becoming an increasing menace. Public transport systems around the world have remained largely the same over the past several decades although the population they serve has burgeoned. This paper aims to demonstrate a low cost IoT based solution to the crowding problem by using smart seats that can detect and display the seat occupancy status in real time over an internet or mobile application. The feasibility of the project was assessed and simulated using the NETSIM simulation software. The results of the software simulation showed promise and hence a hardware prototype was built using the IEEE 802.15.4 standard on the Arduino — Raspberry Pi — nRF platform. The prototype results are positive and show a fully functional IoT system that can be implemented in buses and trains.
<p>It is known that the columnar structures in rapi... more <p>It is known that the columnar structures in rapidly rotating convection are affected by the magnetic field in ways that enhance their helicity. This may explain the dominance of the axial dipole in rotating dynamos. Dynamo simulations starting from a small seed magnetic field have shown that the growth of the field is accompanied by the excitation of convection in the energy-containing length scales. Here, this process is studied by examining axial wave motions in the growth phase of the dynamo for a wide range of thermal forcing. In the early stages of evolution where the field is weak, fast inertial waves weakly modified by the magnetic field are abundantly present. As the field strength(measured by the ratio of the Alfven wave to the inertial wave frequency) exceeds a threshold value, slow magnetostrophic waves are spontaneously generated. The excitation of the slow waves coincides with the generation of helicity through columnar motion, and is followed by the formation of the axial dipole from a chaotic, multipolar state. In strongly driven convection, the slow wave frequency is attenuated, causing weakening of the axial dipole intensity. Kinematic dynamo simulations at the same parameters, where only fast inertial waves are present, fail to produce the axial dipole field. The dipole field in planetary dynamos may thus be supported by the helicity from slow magnetostrophic waves.</p>
Human Language Technology. Challenges for Computer Science and Linguistics, 2020
International Journal of Intelligent Unmanned Systems, 2017
Purpose The purpose of this paper is to propose a new nonlinear guidance law to satisfy terminal ... more Purpose The purpose of this paper is to propose a new nonlinear guidance law to satisfy terminal impact-angle constraints against a stationary target in every possible planar surface-to-surface engagement scenario. The proposed guidance scheme is developed based on the geometry of a circular arc trajectory. The proposed guidance scheme is developed based on the geometry of circular arc trajectory. This trajectory is calculated based on the terminal impact angle and target range. The efficacy of the proposed guidance scheme is demonstrated through numerical simulations. The proposed scheme is compared with existing guidance schemes and relevant analysis is provided. Design/methodology/approach The paper develops a new nonlinear guidance law to satisfy terminal impact-angle constraints against a stationary target in every possible planar surface-to-surface engagement scenario. The proposed guidance scheme is developed based on the geometry of a circular arc trajectory. This guidance s...
Journal of Neuro-Ophthalmology, 2019
Journal of Neuro-Ophthalmology, 2019
Physics of the Earth and Planetary Interiors
The preference for the axial dipole in planetary dynamos is investigated through the analysis of ... more The preference for the axial dipole in planetary dynamos is investigated through the analysis of wave motions in spherical dynamo models. Our study focuses on the role of slow magnetostrophic waves, which are generated from localized balances between the Lorentz, Coriolis and buoyancy (MAC) forces. Since the slow waves are known to intensify with increasing field strength, simulations in which the field grows from a small seed towards saturation are useful in understanding the role of these waves in dynamo action. Axial group velocity measurements in the energy-containing scales show that fast inertial waves slightly modified by the magnetic field and buoyancy are dominant under weak fields. However, the dominance of the slow waves is evident for strong fields satisfying |ω M /ω C | ∼ 0.1, where ω M and ω C are the frequencies of the Alfvén and inertial waves respectively. A MAC wave window of azimuthal wavenumbers is identified wherein helicity generation by the slow waves strongly correlates with dipole generation. Analysis of the magnetic induction equation suggests a poloidal-poloidal field conversion in the formation of the dipole. Finally, the attenuation of slow waves may result in polarity reversals in a strongly driven Earth's core.
2022 8th International Conference on Advanced Computing and Communication Systems (ICACCS)
IP Indian Journal of Anatomy and Surgery of Head, Neck and Brain, 2022
The incidence of venous aneurysm is less than the arterial aneurysms. The knowledge of Popliteal ... more The incidence of venous aneurysm is less than the arterial aneurysms. The knowledge of Popliteal vein aneurysm (PVA) is important as it could be a source of pulmonary embolism, deep vein thrombosis and so could be fatal. PVA could be an incidental finding during the investigations for pulmonary embolism or chronic venous insufficiency. We report a case of left popliteal vein aneurysm in the popliteal fossa in a 65-year-old female cadaver observed during routine dissection. A large saccular dilatation was noted in the left popliteal vein in the distal part of the popliteal fossa. The right popliteal vein was normal.An early diagnosis of PVA with doppler ultrasound examination is important to prevent the occurrence of any thromboembolic events or other major complications.
2017 International Conference on Inventive Computing and Informatics (ICICI), 2017
The Transmission Control Protocol forms the backbone of data communication networks the world ove... more The Transmission Control Protocol forms the backbone of data communication networks the world over. While TCP congestion control protocols operate efficiently over wired networks, their performance in wireless networks leaves a great deal to be desired. Wireless networks are prone to random packet drops for a myriad of reasons apart from network congestion, such as poor channel characteristics, high BER, the hidden node problem and the number of hops between source and destination. This paper aims to perform a comparison of the congestion control schemes of two TCP variants: Reno and New Reno, in a wireless mesh network and analyze the throughput, propagation delay, number of segments retransmitted and number of duplicate acknowledgements received for four different node densities. The behaviour of TCP in wireless networks is observed and plausible justifications attempted. Overall, TCP New Reno shows 40% higher throughput and 25% lower delay as compared to TCP Reno.
Poster: "RANZCR ASM 2010 / R-0135 / RADIOGUIDED OCCULT LESION LOCALIZATION (ROLL) COMBINED W... more Poster: "RANZCR ASM 2010 / R-0135 / RADIOGUIDED OCCULT LESION LOCALIZATION (ROLL) COMBINED WITH WIRE GUIDED LOCALIZATION (WGL) FOR SURGICAL EXCISION OF NONPALPABLE BREAST LESIONS" by: "A. Varma, A. G. M. M. Bourke, M. Brookes, A. Yeo; WA/AU"
Poster: "2016 ASM / R-0057 / MRI of Perianal Fistulas in Crohn's Disease" by: "... more Poster: "2016 ASM / R-0057 / MRI of Perianal Fistulas in Crohn's Disease" by: "W. C. Tsai, A. Varma; TAS/AU"
International Journal of Reproduction, Contraception, Obstetrics and Gynecology, 2022
Background: The aim was to determine whether oral route of maternal hydration was advantageous ov... more Background: The aim was to determine whether oral route of maternal hydration was advantageous over intravenous route in terms of increasing AFI and improving maternal and perinatal outcome in women having borderline oligohydramnios.Methods: At Aarogya hospital, 150 women in third trimester with borderline oligohydramnios (BO) AFI 5.1-8 cm, were divided randomly into two groups, oral hydration group (OG) and intravenous hydration (IVG). Each case was studied on OPD basis. After 2 hours, 48 hours and 1 week of oral or IV hydration. AFI was reassessed by same sonographer. Pre-delivery AFI and various outcome measures were recorded for both groups.Results: There was an increase in AFI by 44.5% in OG from 0 hour till delivery as compared to 30.7% increase in IVG. MSL occurred in 8 (10.7%) women in OG compared to 17 (22.6%) in IVG. FD was found in 4 (5.3%) in OG requiring LSCS compared to 16 (21.3%) in IVG. Total of 59 (78.7%) patients in OG has spontaneous vaginal delivery as compared t...
Poster: "2018 ASM / R-0068 / 3D PRINTING: Hope or Hype" by: "A. Varma, R. Olivotto... more Poster: "2018 ASM / R-0068 / 3D PRINTING: Hope or Hype" by: "A. Varma, R. Olivotto, A. Hodgkinson; QLD/AU"
2017 International Conference on Intelligent Computing, Instrumentation and Control Technologies (ICICICT), 2017
TCP is the standard transport protocol for reliable data communication over the internet. However... more TCP is the standard transport protocol for reliable data communication over the internet. However, TCP behaviour over wireless mesh networks encounters random losses due to channel errors, changing topology and node distance. This paper aims to perform a comparison of TCP Old Tahoe and Tahoe in wireless mesh networks and analyze the throughput, propagation delay, packets retransmitted and number of duplicate acknowledgements received for varying node densities. The anomalous behaviour of TCP in the wireless network is documented, and probable explanations are provided. A comparison of the most suitable variant for each case is concluded. Overall, Tahoe shows 52% lower average throughput and 14% lower delay as compared to Old Tahoe. TCP Old Tahoe appears to be more suitable for lower density networks, whereas TCP Tahoe gives better results for higher density networks.
ArXiv, 2020
In this paper, with a view toward fast deployment of locomotion gaits in low-cost hardware, we us... more In this paper, with a view toward fast deployment of locomotion gaits in low-cost hardware, we use a linear policy for realizing end-foot trajectories in the quadruped robot, Stoch 222. In particular, the parameters of the end-foot trajectories are shaped via a linear feedback policy that takes the torso orientation and the terrain slope as inputs. The corresponding desired joint angles are obtained via an inverse kinematics solver and tracked via a PID control law. Augmented Random Search, a model-free and a gradient-free learning algorithm is used to train this linear policy. Simulation results show that the resulting walking is robust to external pushes and terrain slope variations. This methodology is not only computationally light-weight but also uses minimal sensing and actuation capabilities in the robot, thereby justifying the approach.
Poster: "2016 ASM / R-0058 / Causes of the non-surgical acute abdomen - a pictorial essay&qu... more Poster: "2016 ASM / R-0058 / Causes of the non-surgical acute abdomen - a pictorial essay" by: "W. C. Tsai, A. Varma; TAS/AU"
This paper explores multi-decade tensions in Indo-American relations, emphasizing the formative n... more This paper explores multi-decade tensions in Indo-American relations, emphasizing the formative nature of the colonial legacy on India’s foreign policy and resulting conflict with the Truman Doctrine. By examining the popular perception of foreign policy through political leaders, newspapers, ideological conflicts and State Department records, I illustrate how each nation’s sovereign agenda colored their reception of the other’s global initiatives. The year 1947 marked a point of departure in American foreign policy in two respects; a renewed commitment to economic and military engagement with global affairs under the presidency of Harry Truman, and an expanded interest in diplomacy with developing nations, such as the Republic of India. Contrary to expectations, the promising beginnings of 1947 found no realization amid accelerating hostilities, ultimately leading to the Indo-Soviet Friendship Treaty of 1971. This paper analyzes this understudied period in Indo-American relations –...
2017 International Conference on Inventive Computing and Informatics (ICICI), 2017
With the ever growing global population, crowding in public transport is becoming an increasing m... more With the ever growing global population, crowding in public transport is becoming an increasing menace. Public transport systems around the world have remained largely the same over the past several decades although the population they serve has burgeoned. This paper aims to demonstrate a low cost IoT based solution to the crowding problem by using smart seats that can detect and display the seat occupancy status in real time over an internet or mobile application. The feasibility of the project was assessed and simulated using the NETSIM simulation software. The results of the software simulation showed promise and hence a hardware prototype was built using the IEEE 802.15.4 standard on the Arduino — Raspberry Pi — nRF platform. The prototype results are positive and show a fully functional IoT system that can be implemented in buses and trains.
<p>It is known that the columnar structures in rapi... more <p>It is known that the columnar structures in rapidly rotating convection are affected by the magnetic field in ways that enhance their helicity. This may explain the dominance of the axial dipole in rotating dynamos. Dynamo simulations starting from a small seed magnetic field have shown that the growth of the field is accompanied by the excitation of convection in the energy-containing length scales. Here, this process is studied by examining axial wave motions in the growth phase of the dynamo for a wide range of thermal forcing. In the early stages of evolution where the field is weak, fast inertial waves weakly modified by the magnetic field are abundantly present. As the field strength(measured by the ratio of the Alfven wave to the inertial wave frequency) exceeds a threshold value, slow magnetostrophic waves are spontaneously generated. The excitation of the slow waves coincides with the generation of helicity through columnar motion, and is followed by the formation of the axial dipole from a chaotic, multipolar state. In strongly driven convection, the slow wave frequency is attenuated, causing weakening of the axial dipole intensity. Kinematic dynamo simulations at the same parameters, where only fast inertial waves are present, fail to produce the axial dipole field. The dipole field in planetary dynamos may thus be supported by the helicity from slow magnetostrophic waves.</p>
Human Language Technology. Challenges for Computer Science and Linguistics, 2020
International Journal of Intelligent Unmanned Systems, 2017
Purpose The purpose of this paper is to propose a new nonlinear guidance law to satisfy terminal ... more Purpose The purpose of this paper is to propose a new nonlinear guidance law to satisfy terminal impact-angle constraints against a stationary target in every possible planar surface-to-surface engagement scenario. The proposed guidance scheme is developed based on the geometry of a circular arc trajectory. The proposed guidance scheme is developed based on the geometry of circular arc trajectory. This trajectory is calculated based on the terminal impact angle and target range. The efficacy of the proposed guidance scheme is demonstrated through numerical simulations. The proposed scheme is compared with existing guidance schemes and relevant analysis is provided. Design/methodology/approach The paper develops a new nonlinear guidance law to satisfy terminal impact-angle constraints against a stationary target in every possible planar surface-to-surface engagement scenario. The proposed guidance scheme is developed based on the geometry of a circular arc trajectory. This guidance s...
Journal of Neuro-Ophthalmology, 2019
Journal of Neuro-Ophthalmology, 2019