935 research outputs found
What can we learn from missed opportunities in the transition to open access?
No full textIn this Q&A, Madhan, director of libraries at Jindal Global University, discusses institutional repositories, author-pay open access, publish-review-curate, and the “expensive distraction” of India’s One Nation One Subscription deal
Boundary Layer Flow Acceleration by Paraelectric and Peristaltic EHD Effects of Aerodynamic Plasma Actuators
No full textPlasma actuators based on the OAUGDP TM (One Atmosphere Uniform Glow Discharge Plasma) promise to be a convenient method to modify aerodynamic boundary layers. The development of the OAUGD Plasma has made it possible to locate enough plasma actuators on airfoils and the wings and fuselage of aircraft to have significant effects on flow control and re-attachment at relatively low power cost. In this study OAUGD Plasma actuators have been used to effect flow re-attachment and to manipulate aerodynamic flows, possibly leading to improved methods of flight control. The OAUGDPTM actuators have been tested in the 7 x 11 Inch Low Speed Wind Tunnel at the NASA Langley Research Center during several experimental campaigns that began in the mid 1990’s. The 7 x 11 Inch Low Speed Wind Tunnel is instrumented to conduct drag measurements, smoke flow visualization tests, Pitot tube velocity profile measurements and airfoil flow re-attachment visualization studies.
This thesis is concerned with two EHD (electrohydrodynamic) flow control methods that utilize only RF displacement currents to produce the body forces that accelerate the plasma; paraelectric and peristaltic (traveling wave) flow acceleration. Paraelectric flow acceleration is achieved when the applied electric field acts on the net charge density of the plasma, to provide a body force capable of accelerating the neutral gas to velocities as high as 10 m/sec. During the acceleration process, the plasma moves paraelectrically towards increasing electric field gradients, and drags the neutral gas along with it as the result of frequent ion-neutral Lorentzian collisions. Peristaltic flow acceleration results from a traveling electrostatic wave, analogous to the apparent motion of light in a phased array of bulbs on a theatre marquee. To produce a traveling electrostatic wave, adjacent plasma actuators are energized at progressively larger phase angles. The resulting horizontal electric field produces a body force that accelerates the plasma.
A OAUGDPTM panel or a plasma actuator intended for aerodynamic flow acceleration consists of linear strip electrodes adhering to either side of a dielectric panel. The actuators are energized using RF power at voltages between 0 and 10 kV, and frequencies between 0.5 kHz and 8 kHz. A major contribution described in this thesis was the development of flexible and ceramic panels, the polyphase signal generator based on LabVIEW, and accessories for the polyphase power supply. During development of the plasma actuators, many electrode geometries were tested to achieve the best operating conditions i.e. highest flow velocity. This thesis presents experimental results from several plasma actuator configurations, and performance data from both paraelectric and peristaltic flow acceleration
It Is More than What It Seems: Understanding India’s Perspective on “Responsibility to Protect ”
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Measurements of the local and non-local contributions in decays using LHCb data
No full textIn the study of the decay of B mesons, the observed deviations from standard model predictions could potentially be explained by underestimated non-local hadronic intermediate states. To answer this question, the local and non-local contributions to decays are measured by analysing the invariant dimuon mass distribution in the range: } {(). The analysis uses pp collision data collected by the LHCb experiment between 2011 and 2018 corresponding to an integrated luminosity of 9 . The non-local contributions are modelled using hadronic dispersion relations including a description of intermediate one-particle and two-particle states which scatter to a pair of muons. The largest one-particle states interfering with the local contribution are and and the two-particle states described are , and . The interference from is observed to be small while a large component of the two-particle states, along with the , is observed to destructively interfere with the local contribution. The effect of this interference on the vector current () and axial-vector current () Wilson coefficients, which encode heavy standard model and beyond standard model physics, are discussed. The branching fractions of the one-particle and two-particle states are also measured
Measurements of the local and non-local contributions in B<sup>±</sup>→K<sup>±</sup>μ<sup>±</sup>μ<sup>∓</sup> decays using LHCb data
No full textCan constituent states influence foreign and security policy? Coalitional dynamics in India
No full textBolton’s Anterior and Overall Tooth Size Discrepancy among different malocclusion groups in Chennai Population: An Epidemiological study
No full textAn observational and cross sectional study was done to determine whether there is a difference in intermaxillary tooth size discrepancies among the malocclusion groups and to determine the percentage of tooth size discrepancies outside 1 or 2 standard deviations from Bolton’s inter arch tooth size ratio.
The study two hundred and thirty eight study models randomly selected from archives of the department of orthodontics, Tamil Nadu Government Dental College and Hospital, Chennai, Tamil Nadu. The samples were divided into three groups based on Angle’s classification of malocclusion – class I, class II Div I, and class III, coinciding with skeletal relationship, which was based on the steiner’s ANB angle: class I 05 and class III ANB <o. Each of these groups was again divided into two groups- males and females.
The Bolton’s anterior and overall ratio was calculated for each group. The values were then compared for any possible gender difference and also among each group and with that of Bolton’s normal value.
The study concludes that
1. There were no significant differences in the tooth size discrepancy between male and female.
2. The percentage of subjects with a deviation of more than 1 standard deviation for anterior and overall ratio was 68 and 57.1 respectively.
3. The percentage of subjects with a deviation of more than 2 standard deviation for anterior and overall ratio was 42.4 and 27.7 respectively.
4. Class III malocclusion group showed greater prevalence of tooth size discrepancies greater than 2 standard deviation compared to class II and class I.
5. There were no statistically significant differences in the Bolton anterior and overall ratios between the different malocclusion groups - class I, class II and class III.
6. The anterior ratio of class I and class III in the present study was significantly larger than the Bolton’s normal value for anterior ratio.
Recent technological advances have allowed the introduction of digital callipers, which can be linked to computers for rapid calculation of the Bolton’s anterior and overall ratio and this computer program can virtually eliminate measurement transfer and calculation errors, compared with analysis that requires dividers, rulers and calculators. Few computerised methods like Quick Ceph, HATS, and OrthoCad needs special mention here
A comparative study on distributed active damping of flexible systems
No full textAs systems become more lightweight, to satisfy inertia and size requirements, vibration becomes a prominent factor in their dynamics. This vibration is undesirable and various suppression methods exist such as passive, semi-active, and active. In this thesis, active control methods are explored for this purpose. The present technology utilizes under-actuation for suppression of multiple modes, which has a sub-optimal performance. This work provides a comparative study on the different vibration suppression algorithms, which would aid in developing a distributed placement of actuators (over-actuation) and sensors. The main aim is to achieve multi-mode suppression systems and improve collocation for higher-order modes which facilitates accurate control of the end-effector of a system. A comparison is drawn between point actuation and over-actuation in terms of energy consumption, amount of damping, and precision. Also, a new control strategy is developed to circumvent the limitations posed by the present control strategies such as low frequency spillover and steady-state error. The benefits in terms of damping and shortcomings are presented based on the conclusion drawnMechanical Engineerin
An Optimal Multilayer Perceptron with Dragonfly Algorithm for Intrusion Detection in Wireless Sensor Networks
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