1,722,164 research outputs found
Improved qualification and algorithms for illinisat-2 attitude determination and control
No full textThe University of Illinois has developed the IlliniSat-2 CubeSat bus, a generic scalable and modular design, utilizing commercially available off the shelf (COTS) parts. The Attitude Determination and Control System (ADCS) of the bus is purely magnetic, relying on magnetometers for determination and magnetorquers for actuation. The pure magnetic ADCS is favorable because of its low power, volume and mass contributions to the satellite’ platform, but this comes at the cost of weak system controllability and observability, and no flight heritage. To improve system reliability for operation in space, CubeSim, a hardware in the loop (HIL) simulation suite has been developed. The basic CubeSim setup consists of a tri-axial square Helmholtz cage (HC3), a dynamic power supply (PS), and a software package simulating the satellite’s attitude dynamics.
This thesis is split into three parts, the first section discusses the different methods for calibrating the PS and the HC3 to generate desired magnetic fields, and HIL simulation results for traditional determination and control algorithms, using lab grade sensors. Next, using the calibrated basic CubeSim setup, calibration of flight sensors and HIL results are shown.
The second part of the thesis discusses the hardware and software augmentation to the basic CubeSim for higher fidelity ADCS simulations, and the calibration of inertial sensors, necessary for increasing the observability of the ADCS.
Finally, the third section discusses the trajectory generation for the underactuated pure magnetic ADCS, named as the “Navigation controller”, used to generate reference trajectories for the ADCS that is finite horizon optimal. The trajectory is obtained using two independent techniques, and the computational complexity and speed is compared for onboard usage.Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2020-05-01The student, - Vedant, accepted the attached license on 2018-04-26 at 12:06.The student, - Vedant, submitted this Thesis for approval on 2018-04-26 at 14:08.This Thesis was approved for publication on 2018-04-27 at 12:15.DSpace SAF Submission Ingestion Package generated from Vireo submission #12523 on 2018-08-31 at 17:21:41Made available in DSpace on 2018-09-04T20:42:00Z (GMT). No. of bitstreams: 2
VEDANT-THESIS-2018.pdf: 13038429 bytes, checksum: 6cfbb9a8b6d31339294d06a9972637ae (MD5)
LICENSE.txt: 4205 bytes, checksum: 4116bbc34cad8b0850f1952685d1296f (MD5)
Previous issue date: 2018-04-27Embargo set by: Seth Robbins for item 107323
Lift date: 2020-09-04T20:42:08Z
Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemU of I Only Restriction Lifted for Item 107323 on 2020-09-05T09:15:26Z
Artificial Intelligence and its probable military disruptions
No full textThis chapter explores the usage of Artificial Intelligence (AI) in the Indian Armed Forces. This chapter is premised on the observation that AI is changing the way geopolitics is conducted. Not only the advanced technology like AI but all Information and Communication Technologies (ICT) have also become an integral part of our lives, with their presence in the industries such as education, infrastructure, banking, consumer, and even defence. Military technologies make use of AI in either defensive or offensive dimensions. Both dimensions are explored in this chapter. It also discusses the relationship between AI and Semiotics, elaborating on its role in the three branches of the Indian Armed Forces – Army, Navy, and the Air Force. Further, this chapter highlights the challenges of implementing AI in the military. Providing the future prognosis, the chapter concludes with suggestions and recommendation
A self corrective vortex fluxing method for viscous fluid structure interaction problems
No full textComputational Fluid Dynamic Solvers for flow structure interaction problems rely on a delicate treatment of fluid and grid properties close to the boundary. Although such an approach is accurate, it proves to be inflexible when applied to complex deforming geometries. Here we combine remeshed vortex methods with a panel method to design a new Vortex Fluxing scheme that uses no special treatment of flow properties at the boundary. It was found that the panel method is capable of correcting any spurious vorticity flux into the wall during the no slip boundary application. This enables highly accurate, robust Direct Numerical Simulations by relaxing the need for small timesteps and allowing the use of coarse regular computational grids. The methodology was validated for rigid, rotating and deforming bodies.Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2020-08-01The student, Vedant Dubey, accepted the attached license on 2018-07-06 at 01:53.The student, Vedant Dubey, submitted this Thesis for approval on 2018-07-06 at 02:04.This Thesis was approved for publication on 2018-07-06 at 10:35.DSpace SAF Submission Ingestion Package generated from Vireo submission #12750 on 2018-09-27 at 11:16:39Made available in DSpace on 2018-09-27T16:30:19Z (GMT). No. of bitstreams: 2
DUBEY-THESIS-2018.pdf: 6418473 bytes, checksum: a347fe74ea9976e2b896c56d595fbeb4 (MD5)
LICENSE.txt: 4209 bytes, checksum: 820159346747effad92786f714e1f993 (MD5)
Previous issue date: 2018-07-06Embargo set by: Seth Robbins for item 107778
Lift date: 2020-09-27T16:30:34Z
Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemEmbargo set by: Seth Robbins for item 107778
Lift date: 2020-09-27T16:31:43Z
Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemEmbargo set by: Seth Robbins for item 107778
Lift date: 2020-09-27T16:34:29Z
Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemU of I Only Restriction Lifted for Item 107778 on 2020-09-28T09:15:30Z
The Online Learning Curve — A Special Edition of Ithaca Now
No full textITHACA — This week, Ithaca Now takes a special deep dive into the issue of online education. Hear Antonio Ferme and Vedant Akhauri explore the quick shift to online and hybrid learning, speaking to a variety of different teachers, students, and more!
Originally aired on December 13, 2020.
From: wicb.orghttps://digitalcommons.ithaca.edu/covid19/1005/thumbnail.jp
Cyber security structure in India
No full textWith the evolving digital technologies, there is a continuous evolution of cyber threat. The internet is already on its way to become ubiquitous. There are numerous applications built on internet and digital platforms, offering almost all the services to the public. Such ubiquitous presence is creating socio-technical iterations crafting a new social. Within this new social, cyber security should be prioritized. Given the rise of cybercrimes, developing an ecosystem that is capable of understanding new age complexities and offer swift security mechanisms is necessary. This chapter emphasizes on the cyber security structure of India and discusses how the country is responding to cyber security and data protection challenges
Appendix-1,2 – Supplemental material for Influence of respondent type on relationships between safety climate and safety performance in manufacturing firm
No full textSupplemental material, Appendix-1,2 for Influence of respondent type on relationships between safety climate and safety performance in manufacturing firm by Vedant Singh and Anita Verma in Proceedings of the Institution of Mechanical Engineers, Part O: Journal of Risk and Reliability</p
Optimal control co-design of attitude control systems
No full textAttitude control is the process of orienting a spacecraft toward a desired point in space. Conventional systems for attitude control have been designed without considering the compliant response of the spacecraft. This leads to complex control algorithms that avoid exciting vibrational modes of the spacecraft structures, particularly deployable panels. Most conventional approaches try to modify the deployable structures to reduce mechanical compliance, which comes at a mass and cost penalty. The performance of such systems can be greatly improved if the system is optimized from both a design and control perspective simultaneously, known as control co-design (CCD).
This dissertation proposes new mathematical modelling methods and CCD optimization strategies to support the creation of novel Attitude Control System (ACS) that utilizes mechanical compliance of deployable panels to provide attitude control. New contributions to optimization methods utilize reinforcement learning algorithms adapted for CCD problems. These algorithms can aid in quickly exploring the design space of novel systems and provide design rules to help design systems which are close to optimal without needing to solve a new optimization problem each time. These new methods will be used to develop Strain Actuated Solar Arrays (SASA), an ACS that offers attitude stabilization capability at the nano-radian scale by actively canceling mechanical vibrations on the spacecraft. The precise levels of pointing are enabled by designing the system while considering the control trajectories that SASA is expected to execute. The co-design studies will then be used to expand the capabilities of the SASA system to not only provide attitude control at the small angles, but also to provide attitude maneuvering capability for arbitrarily large angles. This extension to SASA is called Multifunctional Structures for Attitude Control (MSAC), which works like a momentum exchange device and can serve as a replacement to conventional reaction wheel assemblies and control momentum gyroscopes.
The dissertation concludes with hardware-in-the-loop validation of SASA and MSAC prototypes designed using the new models and methods. The response of these prototypes is compared against the predicted performance and serves as a validation for the new models and techniques developed.Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2023-05-11 without embargo termsThe student, - Vedant, accepted the attached license on 2021-07-01 at 16:14.The student, - Vedant, submitted this Dissertation for approval on 2021-07-01 at 16:21.This Dissertation was approved for publication on 2021-07-12 at 16:34.DSpace SAF Submission Ingestion Package generated from Vireo submission #16746 on 2023-05-11 at 16:57:3
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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