141,163 research outputs found
Modeling of the Hα Emission from ADITYA Tokamak Plasmas
No full textThe spatial profile of Hα spectrum is regularly measured using a high-resolution multi-track spectrometer in ADITYA tokamak to study the neutral particle behavior. The Monte Carlo neutral particle transport code DEGAS2 is used to model the experimental Hα spectral emissions. Through the modeling of the spectral line profile of Hα, it is found that the neutral hydrogen, which is produced from molecular hydrogen and molecular hydrogen ion dissociation processes contributes 56% to the total Hα emission, and the atoms which are produced from charge-exchange process have 30% contribution. Furthermore, the experimentally measured spatial profile of chord integrated brightness was modeled for the two plasma discharges having relatively high and low density to understand the neutral particle penetration. The presence of neutrals inside the core region of the ADITYA tokamak is mainly due to the charge-exchange process. Furthermore, it is observed that neutral particle penetration is lower in higher density discharge
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Aditya Kulkarni: Patrones de movilidad humana vinculados a ubicaciones propensas a COVID-19
No full textDescripción de esta presentación:
Esta presentación fue hecha por Aditya Kulkarni, Universidad de Minnesota. El título de la presentación es: "Patrones de Movilidad Humana Vinculados a Ubicaciones Propensas COVID-19." Centro de Información de COVID. Estudiante de Pregrado del reto estudiantil. Ganador del 3er lugar.
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Descripción de los seminarios web del CIC:
Cada mes, el equipo del Centro de Información de COVID (junto con el Northeast Big Data Innovation Hub) reúne a un grupo de investigadores que estudian diversos aspectos de la pandemia actual, para compartir sus investigaciones y responder preguntas de nuestra comunidad. Los eventos muestran los esfuerzos continuos de los científicos en la lucha contra el COVID-19, incluyendo oportunidades de colaboración
Mirnov coil data analysis for tokamak ADITYA
No full textThe spatial and temporal structures of magnetic signal in the tokamak ADITYA is analysed using recently developed singular value decomposition (SVD) technique. The analysis technique is first tested with simulated data and then applied to the ADITYA Mirnov coil data to determine the structure of current peturbation as the discharge progresses. It is observed that during the current rise phase, current perturbation undergoes transition from m=5 poloidal structure to m=4 and then to m=3. At the time of current termination, m=2 perturbation is observed. It is observed that the mode frequency remains nearly constant (≈10 kHz) when poloidal mode structure changes from m=4 to m=2. This may be either an indication of mode coupling or a consequences of changes in the plasma electron temperature and density scale length
Supplemenatry_Table_1 – Supplemental material for Cost-Utility Analyses in US Orthopaedic Foot and Ankle Surgery: A Systematic Review
No full textSupplemental material, Supplemenatry_Table_1 for Cost-Utility Analyses in US Orthopaedic Foot and Ankle Surgery: A Systematic Review by Aditya V. Karhade and John Y. Kwon in Foot & Ankle Specialist</p
Aditya Pratap Deo, Kings, Spirits and Memor y in Central India: Enchanting the State (London, New York: Routledge, South Asia Edition, 2022)
No full textBook Review of Aditya Pratap Deo, Kings, Spirits and Memor y in Central India: Enchanting the State (London, New York: Routledge, South Asia Edition, 2022
Effect of periodic gas-puffs on drift-tearing modes in ADITYA/ADITYA-U tokamak discharges
No full textThe effect of a periodic train of short gas-puff pulses on the rotation frequency and amplitude of drift-tearing modes has been studied in ADITYA/ADITYA-U tokamak. The short gas puffs, injecting approximately similar to 10(17)-10(18) molecules of fuel gas (hydrogen) at one toroidal location, are found to concomitantly decrease the drift-tearing mode rotation frequency and the mode amplitude during the period of injection and then recover back to its initial values when the gas pulse is over. This leads to a periodic modulation of the rotation frequency and amplitude of the drift-tearing modes that is correlated with the periodicity of the gas pulse injection. The underlying mechanism for this change in the mode characteristic appears to be related to gas puff induced change in the radial profile of the plasma pressure in the edge region that brings about a reduction in the diamagnetic drift frequency. Detailed experimental measurements and BOUT++ code simulations support such a reduction in diamagnetic drift frequency. Our results reveal a close interaction between the edge dynamics and core MHD phenomena in a tokamak that could help us better understand the rotation dynamics and amplitude pulsations of magnetic islands.SP
On the AC^0[oplus] Complexity of Andreev’s Problem
No full textAndreev’s Problem is the following: Given an integer d and a subset of S subset F_q x F_q, is there a polynomial y = p(x) of degree at most d such that for every a in F_q, (a,p(a)) in S? We show an AC^0[oplus] lower bound for this problem.
This problem appears to be similar to the list recovery problem for degree-d Reed-Solomon codes over F_q which states the following: Given subsets A_1,...,A_q of F_q, output all (if any) the Reed-Solomon codewords contained in A_1 x *s x A_q. In particular, we study this problem when the lists A_1, ..., A_q are randomly chosen, and are of a certain size. This may be of independent interest
Role of magnetohydrodynamic activity in sawtooth induced heat pulse propagation in ADITYA tokamak
No full textFast propagation of sawtooth induced heat pulse is observed in the magnetohydrodynamic (MHD) active plasmas of ADITYA tokamak. The sawtooth crash deposits heat beyond the inversion radius, which gets transported to the edge region of the plasma, and is reflected as inverted sawtooth modulation in the edge channels of electron cyclotron emission (ECE) and spectral line emission. The time-lag analysis on ECE signal reveals the propagation time from plasma core to edge of ∼150 µ s. From this analysis, the estimated transient electron heat diffusivity is found to be ∼50–60 m ^2 s ^−1 , which is ten times higher than that of power balance heat diffusivity , in the MHD active discharges of ADITYA. It has been observed that the presence of MHD ( m / n = 2/1, 3/1) activity in the intermediate region between the q = 1 and the edge radii, significantly influences the heat transport from the plasma core to the edge region. Stochastic magnetic field region formation with overlapping m / n = 2/1 and 3/1 MHD islands facilitates the fast heat-pulse propagation during a sawtooth crash in ADITYA tokamak. The disparity between the measured and the power-balance estimated diffusivity is significantly reduced by considering the electron heat diffusivity due to stochastization of magnetic field in the intermediate region
Real-time feedback control system for ADITYA-U horizontal plasma position stabilisation
No full textThe ADITYA-U tokamak (R-0 = 0.75 m, a = 0.25 m) is designed to shape plasma column in both single and double null diverter configurations. It is quite well known that sustaining a shaped plasma in tokamak requires very good plasma column position control, both horizontal and vertical. An FPGA-based proportional-integral-derivative (PID) control system has been designed and operated to achieve horizontal plasma position control in ADITYA-U tokamak. The complete system has been rigorously tested with sample signals before implementing to the ADITYA-U plasma discharges. The control system is integrated and time-synchronized with the plasma discharge operation of ADITYA -U. Furthermore, the system has been trained to take appropriate actions during the disruption or plasma failure in the tokamak operation. Detailed experimental results have been obtained by the operation of the digital PID controller. The complete design, installation, operation, tuning of the system along with all the relevant testing and operating experience of the digital PID controller for real-time horizontal plasma position control is presented in the paper.SP
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