Faculty Publications
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Item Testing of foams(Springer Singapore, 2019) Gupta, N.; Zeltmann, S.E.; Luong, D.D.; Doddamani, M.Foams are lightweight cellular materials that are widely used in applications such as packaging, thermal insulation, sound absorption, underwater vehicle structures, and as the core in sandwich structures used in aircraft. Testing of foams to obtain reliable properties that are relevant to a given application is a significant challenge. High damping, high compressive or tensile strain, and high volume of air in the structure are among the challenges that make it difficult to apply the common test methods to these materials. For example, use of strain gauges for tensile or compression testing is usually not possible because bonding the strain gauges to the surface of a cellular material may not be possible, the small measurement range of a strain gauge may not be enough to capture the strain in the entire loading range, and microscopic material structure may dominate the measurement. This chapter discusses test techniques that include quasi-static compression, high strain rate compression, impact, dynamic mechanical analysis, vibration methods, and imaging techniques that are relevant to testing of foams. The imaging methods include ultrasonic imaging and microCT-scanning. Test techniques are described and results on representative foam materials are presented to understand the test outcomes. © Springer Nature Singapore Pte Ltd. 2019.Item 3D Printing of Syntactic Foams for Marine Applications(Springer International Publishing, 2020) Gupta, N.; Doddamani, M.Syntactic foams are hollow particle filled lightweight composite materials that are widely used in structural applications in underwater marine vessels. Additive manufacturing (AM), also called 3D printing, methods are now being developed for printing parts of syntactic foams. These methods provide advantage that the entire part can be printed without the requirement of machining or joining and eliminates stress concentration locations. The present work is focused on describing the method of creating a syntactic foam filament for fused filament fabrication type printers and then developing parameters for printing syntactic foams parts using commercial printers. High density polyethylene resin is used as the matrix material with fly ash cenospehres and hollow glass microballoons as the fillers for creating syntactic foams. One of the major challenges is to minimize the fracture of hollow particles during filament manufacturing and 3D printing, which is addressed by parameter optimization during processing. Results show that the syntactic foam specimens are successfully printed and their properties are comparable to the injection molded specimens of the same compositions. © Springer Nature Switzerland AG 2020.Item 3D printing of fly ash-based syntactic foams(Elsevier, 2021) Doddamani, M.; Gupta, N.In addition to the ease of fabrication using a wide range of forming processes, thermoplastic polymers are recyclable, which is a strong driving force behind their industrial applications. This chapter deals with manufacturing thermoplastic matrix lightweight composites called syntactic foams (SFs) using in the fused filament fabrication 3D printing process. High-density polyethylene (HDPE) is used as the matrix material and fly ash cenospheres are used as the filler. The development of SFs with cenospheres serves a dual purpose of beneficial utilization of industrial waste fly ash and a reduction in the component cost. Hollow fly ash cenospheres are mixed with HDPE to form a cenosphere/HDPE blend, which is extruded in the form of filaments for commercial 3D printers. Single-screw extruder parameters are optimized to develop eco-friendly SF filaments with minimum cenosphere fracture and homogeneous mixing of constituents. Fly ash-based SFs are successfully 3D printed for mechanical characterization and their properties are observed to be comparable to injection molded specimens of the same compositions. 3D printing of industrial components is successfully demonstrated with potential weight saving capabilities of 8% in addition to reduced polymer consumption to the tune of 4.64 million tons globally per year. © 2022 Elsevier Inc. All rights reserved.Item Fuzzy file management(2011) Gupta, N.; Abhinav, K.R.; Annappa, B.In this paper we discuss a fuzzy logic approach to improve file management and organization. Incorporating fuzzy techniques in the file management process provides an intelligent way of maintaining files on the computer system. The fuzzy inference engine implements the decision making process required to select files for various file operations. This provides user convenience and system efficiency. We develop a fuzzy copy command in order to integrate fuzzy logic into the UNIX system's file management procedures and present examples which demonstrate the effectiveness of the command in organizing files. © 2011 IEEE.Item Learning by creating: Interactive programming for Indian high schools(2012) Gupta, N.; Tejovanth, N.; Murthy, P.In this paper we discuss results and observations based on empirical studies of introducing programming using Scratch-Arduino to high school students. We analyse the programming experience of students across diverse educational and economic backgrounds, culture and region. Learning of key programming and electronics concepts was measured during the exercise. Results indicate that these fundamentals can be imparted at high schools in the Indian educational context. We find that the introduction of logic programming and computer-hardware interfacing at the high school level is advantageous in terms of creating an interactive environment fostering learning and creativity. © 2012 IEEE.Item Educational computing for the blind in India: Design, development and learning impact(2012) Gupta, N.; Raghavan, A.; Shanbhogue, M.; Jain, A.The aim of this paper is to present software engineering methodologies that were employed in developing educational solutions for the visually impaired. Empirical studies and experiments were conducted to measure the impact of the educational tools on the learning and cognitive abilities of the target user group. This study highlights the various technological and design challenges that were faced while developing and deploying these customized learning solutions. Observations and results indicate that there is significant merit in developing and utilizing such applications for the educational empowerment of the blind. © 2012 IEEE.Item Fuzzy sentiment analysis on microblogs for movie revenue prediction(IEEE Computer Society, 2013) Gupta, N.; Abhinav, K.R.; Annappa, B.With the advent of microblogging in recent years, people voice their views about products, especially movies. Microblogs are rich sources of data that can be analyzed to derive useful knowledge like larger public opinion on a product, which can be utilized to derive sales performance patterns. In this paper we propose a novel fuzzy approach for evaluating sentiments expressed in microblogs, which are incorporated in text mining methodologies to predict weekly movie revenues. © 2013 IEEE.Item Tensile properties of cenosphere/HDPE syntactic foams manufactured using an industrial scale injection molding technique(DEStech Publications, 2015) Kumar, B.R.B.; Doddamani, M.; Gupta, N.Composite materials having hollow fillers in a matrix material are known as syntactic foams. Such lightweight composites are used in a variety of applications ranging from sports, transportation, aviation and marine structures due to high dimensional stability, compressive strength and low moisture absorption. The present work is focused on using an industrial scale injection molding technique for fabricating syntactic foams and characterizing the fabricated syntactic foams for tensile properties. Use of such techniques can help in developing foams with high quality for bulk applications. Hollow fly ash cenospheres are used as the filler particles due to their low cost. Use of these industrial waste particles in beneficial applications can also help in their disposal. The present work is aimed at characterizing syntactic foams for tensile properties and investigating the effect of filler content. The syntactic foam density can be changed by changing cenospheres content. Cenospheres in 20 and 60 wt.% are used in syntactic foams in the present work. ASTM D 638-10 standard for the tensile properties of unreinforced and reinforced plastics is followed for the tensile testing. © © 2015 by DEStech Publications, Inc. and American Society for Composites. All rights reserved.Item Tribological response of cenosphere/epoxy syntactic foams(DEStech Publications, 2015) Manakari, V.; Parande, G.; Bafna, K.; Doddamani, M.; Gupta, N.Fly ash cenospheres are generated in thermal power plants as waste materials. Use of these waste materials in beneficial applications is desired. The present work deals with developing syntactic foams with fly ash cenospheres filled in epoxy resin matrix. Such syntactic foams can be used as core materials in sandwich composites. The fabricated syntactic foams are evaluated for dry sliding wear behavior. Sliding velocity and filler content were the study parameters, effects of which were analyzed on wear rate. Specimens were prepared with 10, 30 and 50 wt. % cenospheres for the study. Sliding against hardened ground steel on a pin-on disc wear testing machine was conducted. The experimental results and subsequent analysis showed that the addition of cenospheres as filler material in epoxy matrix considerably increases the wear resistance of the composites. The craters on the specimen surface due to presence of cenospheres play important role in the wear process. © © 2015 by DEStech Publications, Inc. and American Society for Composites. All rights reserved.Item Investigating the "wisdom of crowds" at scale(Association for Computing Machinery, Inc acmhelp@acm.org, 2015) Mysore, A.S.; Yaligar, V.S.; Ibarra, I.A.; Simoiu, C.; Goel, S.; Arvind, R.; Sumanth, C.; Srikantan, A.; Bhargav, H.S.; Pahadia, M.; Dobhal, T.; Ahmed, A.; Shankar, M.; Agarwal, H.; Agarwal, R.; Anirudh-Kondaveeti, S.; Arun-Gokhale, S.; Attri, A.; Chandra, A.; Chilukuri, Y.; Dharmaji, S.; Garg, D.; Gupta, N.; Gupta, P.; Jacob, G.M.; Jain, S.; Joshi, S.; Khajuria, T.; Khillan, S.; Konam, S.; Kumar-Kolla, P.; Loomba, S.; Madan, R.; Maharaja, A.; Mathur, V.; Munshi, B.; Nawazish, M.; Neehar-Kurukunda, V.; Nirmal-Gavarraju, V.; Parashar, S.; Parikh, H.; Paritala, A.; Patil, A.; Phatak, R.; Pradhan, M.; Ravichander, A.; Sangeeth, K.; Sankaranarayanan, S.; Sehgal, V.; Sheshan, A.; Shibiraj, S.; Singh, A.; Singh, A.; Sinha, P.; Soni, P.; Thomas, B.; Tuteja, L.; Varma-Dattada, K.; Venkataraman, S.; Verma, P.; Yelurwar, I.In a variety of problem domains, it has been observed that the aggregate opinions of groups are often more accurate than those of the constituent individuals, a phenomenon that has been termed the "wisdom of the crowd." Yet, perhaps surprisingly, there is still little consensus on how generally the phenomenon holds, how best to aggregate crowd judgements, and how social influence affects estimates. We investigate these questions by taking a meta wisdom of crowds approach. With a distributed team of over 100 student researchers across 17 institutions in the United States and India, we develop a large-scale online experiment to systematically study the wisdom of crowds effect for 1,000 different tasks in 50 subject domains. These tasks involve various types of knowledge (e.g., explicit knowledge, tacit knowledge, and prediction), question formats (e.g., multiple choice and point estimation), and inputs (e.g., text, audio, and video). To examine the effect of social influence, participants are randomly assigned to one of three different experiment conditions in which they see varying degrees of information on the responses of others. In this ongoing project, we are now preparing to recruit participants via Amazon's Mechanical Turk.