178 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
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
Modeling and analysis of canonical turbulent shear flows
No full textTurbulent flows are ubiquitous in engineering systems, however analyzing such flows around engineering-relevant geometries using turbulence-resolving simulations is difficult due to computational cost constraints. Therefore, to advance our ability to predict these flows, we need physics-based models that alleviate the computational cost while retaining high accuracy. The thesis contributes to this broad challenge by introducing two models for high-speed wall-bounded turbulent flows and through a detailed study of 3D effects in turbulent shear flows.
In Part I of this thesis, the modeling of high-speed wall-bounded turbulent flows is explored using different solution fidelities. First, a low-cost modular method is developed that estimates the mean velocity and temperature profiles, and hence the friction and heat transfer coefficients for a given Mach number, wall temperature and Reynolds number. The predictionsmade by the proposed method produce up to 8 and 11% error in wall shear stress and heat flux with respect to DNS data, hence making it a useful tool for the preliminary engineering design
calculations of high-speed vehicles. Second, a new wall-model is developed with the goal of improving the prediction accuracy of wall heat flux over the current state-of-the-art for wall-modeled large eddy simulations of high-speed wall-bounded flows. The proposed model introduces two new modeling components: a simple model for the near-wall diffusion
of the turbulence kinetic energy, and an altered near-wall damping of the thermal eddy diffusivity. Both a priori and a posteriori tests are performed using reference DNS data of boundary layers up to Mach 10. The a priori errors for the proposed model are confined within 5%, although the a posteriori errors are larger, partly due to about 2% and 5% commutation error in the wall friction and heat transfer coefficients emerging from applying the wall-model on instantaneous data instead of averaged data.
In Part II of this thesis, a detailed study on three-dimensional effects in turbulent shear layersis performed with the objective of increasing our basic understanding. The skewed shear layers are generated by shearing two misaligned boundary layers at their interface. In the long-time, a skewed shear layer approaches the planar shear layer state, provided that it is analyzed in the mean shear frame. The most prominent three-dimensional effect is the presence of a planar jet-like flow orthogonal to the mean shear direction, that decays slowly in time. Nonetheless, the decaying jet has limited influence on the overall shear layer once its relative strength diminishes. Consequently, the mean statistics of a skewed shear layer eventually evolve similar to a planar shear layer despite the continued presence of a spanwise jet
Fractals
No full textThis paper presents Fractals, an exploratory music project by the author, which aims to uniquely blend various genres across multiple sections. The distinctiveness of this project lies in the author’s experience as a versatile musician, with experience ranging from rock bands and big bands to chamber orchestras, coupled with proficiency as a producer/DJ. This background of musical experience allows the author to approach the blend of genres with a unique perspective. The collection of songs serves as a precursor for four separate EPs: The project is not just a musical amalgamation but also an academic inquiry into the evolution of these genres, including an analysis of influential works and a reflection on the potential for innovative soundscapes in electronic music. Through this project, the author endeavors to leave a personal stamp on the electronic music scene, showcasing a synthesis of diverse musical influences and creative experimentation. This endeavor aims to contribute a distinctive auditory experience to the electronic music landscape, underlined by the author\u27s unique musical journey. This paper was written with the assistance from generative artificial intelligence. Additional information in Appendix II.https://remix.berklee.edu/graduate-studies-production-technology/1375/thumbnail.jp
Analyzing Network (Non-)Neutrality for Monopolistic, Competing, or Vertically Integrated Content Providers with a Unified Model
No full textInternational audienceThis paper deals with the hot and sensitive network neutrality debate. It designs a model simultaneously encompassing several scenarios regarding the content-providing market structure: a monopolistic content provider, competitive ones, and a vertically-integrated one facing a non vertically-integrated competitor. We each time compare the outputs when non-neutral, weak neutral or strong neutral policies are applied, in order to get insights regarding the possible consequences of each type of neutrality regulation
Fuel consumption optimization in air transport: a review, classification, critique, simple meta-analysis, and future research implications
No full textHow Do Household and Spatial Factors Matter While Examining Inequality in Credit Availability? Evidence from an Emerging Economy
No full textFuel consumption optimization in air transport: a review, classification, critique, simple meta-analysis, and future research implications
No full textEthical Considerations in Deploying AI Systems in Public Domains: Addressing the ethical challenges of using AI in areas like surveillance and healthcare
No full textThe general use of AI technology, especially in public sectors like security and even in the medical field, has been subject to a number of questions to do with ethics. This paper aims to understand the ethical dilemmas concerning the instantiation of Artificial Intelligence in these fields, specifically privacy, bias, responsibility, and openness concerns. In security, advanced technologies like facial recognition and predictive policing attract concerns pertaining to violation of privacy, importation of race bias, and lack of social control, among others. In health care, the AI systems employed in the diagnosis and treatment of patients call into question issues to do with patient choices, data privacy, and discrimination in medical treatment. Within the scope of the paper, the author considers contemporary ethical standards and legislation regulating AI creation and finds some deficiencies. In response to these issues, some of the potential work for the future highlighted in the paper includes enhancing the legal policies in the area of AI, insisting on the importance of ethical multi-disciplinary research, and creating awareness of the effects of AI in society. It underlines the requirement for responsible and explainable AI, the availability of efficient tools helping in monitoring and controlling AI, and increased people’s involvement in creating AI policies to state that the launched AI technologies will be compliant with the people’s benefit. With these suggestions, the paper sought to add knowledge to the ongoing discussion on AI ethics and ensure that decent utilization of AI systems is enhanced with reverence to human rights and ethical norms
Impact of TQM on organisational performance: The case of Indian manufacturing and service industry
No full textThis study is principally focused on the implementation of Total Quality Management (TQM) in Indian industries and to study its influence on the organizational performance. The study has been conducted in five manufacturing and three service companies in north India. The selected companies are listed in Confederation of Indian Industries (CII). The data used for this study was the combination of primary and secondary data and the focus was on examining the extent of TQM implementation in Indian industries. The hypotheses and conceptual framework were designed in accordance with Indian context. The completely useful 236 samples were collected from eight small and medium-sized Indian (SME) manufacturing and service companies. The data was classified into two categories i.e. Managers and Workers. The data collected then analyzed using SPSS-AMOS 24. All the hypotheses were positively fit with the conceptual model and hence showed the positive impact of TQM on organizational performance (OP). All the values were significant and consistent with previous studies. It was found that there is no such difference of literacy about TQM among the two groups and TQM elements are positively related to the performance factors of the Indian organizations. Finally, the findings of this study provides a valuable knowledge regarding TQM practices from Indian manufacturing and service sector perspective. Keywords: Total quality management (TQM), Small and medium sized enterprises (SMEs), Organizational performance, Indian manufacturing and service firms, Structural equation modelling (SEM
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