19 research outputs found
Performance Analysis of Process Parameters on Machining Titanium (Ti-6Al-4V) Alloy Using Abrasive Water Jet Machining Process
No full textAbstractOwing to its light weight and corrosive resistant, Titanium (Ti-6Al-4V) alloy is mainly utilized in fabricating medical device applications. Since it has high strength, it is very difficult to machine alloy using conventional machining. In the present study, an endeavor has been made to machine titanium alloy using AWJM process. Since the process involves with less heat affect zone and higher material removal, it is possible to enhance machinability of workpiece. It has attempted to find the influence of process parameters on surface roughness and topography for enhancing the process. It has been observed that the abrasive flow rate and standoff distance has the most significant role on determining surface quality
Thermoelectric characterization of one- and two- dimensional materials
No full textThermoelectric materials are useful for a wide range of applications like waste heat removal, solid state cooling, and power generation in space missions etc. A material's thermoelectric figure of merit (zT), which determines its performance in the applications listed above, depends on its Seebeck coefficient (S), electrical conductivity (σ), and thermal conductivity (κ) as zT=S2σT/κ. Low dimensional materials like nanowires (1D) or atomically thin films (2D) are promising as they exhibit lower thermal conductivities or higher power factors (S2σ) compared to their bulk (3D) counterparts. The thermal and electrical properties of these low dimensional materials could be further tuned by modifying their microstructure to achieve higher zTs. To achieve such material tuning in a controlled fashion, it is necessary to understand the physical mechanisms that govern the relationships between a material's microstructure and its thermoelectric properties. Reliable experimental techniques and proper interpretation of the experimental results are essential to gain insights into the physical mechanisms of interest.
This dissertation addresses the characterization of thermoelectric properties of one- and two-dimensional materials with the goal of studying the governing physical mechanisms. An experimental study on the Seebeck coefficient and electrical conductivity of atomically thin Molybdenum disulphide (MoS2), a two-dimensional semiconducting material, is presented. Seebeck coefficient and electrical conductivity are electronic transport properties. In MoS2 and atomically thin materials, the electron transport is heavily influenced by the localized states formed in their band gaps. By fitting the experimentally obtained temperature and gate voltage dependence of S and σ with a theoretical model, a determination of the nature of the localized states and the electron transport mechanism is made.
For the one-dimensional materials, the focus is on the measurement of their thermal conductivity. Most of the advances in the figure of merit were achieved in the recent past by reducing the thermal conductivity. In this light, understanding the phonon transport in the low dimensional materials gains importance. A suspended bridge measurement platform is a very commonly used technique to measure thermal conductivity of one-dimensional materials. This technique is very useful for studying the underlying fundamental transport physics as it allows measurement on an individual 1D structure, as opposed to 3ω and TDTR methods which can only measure an assembly of 1D materials. Combining this measurement technique with precise microstructure characterization using transmission electron microscopy (TEM), the influence of the microstructure on thermal transport can be deducted. In a study done previously on silicon nanowires, different but similarly made 1D structures were used for microstructure characterization and thermal measurement. This mismatch introduces an uncertainty in the correlation between microstructure and the phonon transport. In this dissertation, a modification to the usual measurement platform is presented which allows TEM imaging and thermal measurement on the same 1D structure. Furthermore, refinements to the measurement principal that have been implemented in our lab to enable measurement on much finer 1D structures are discussed in this dissertation.Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2019-08-01The student, Krishna Vasanth Valavala, accepted the attached license on 2017-07-13 at 22:14.The student, Krishna Vasanth Valavala, submitted this Dissertation for approval on 2017-07-14 at 10:26.This Dissertation was approved for publication on 2017-07-14 at 11:12.DSpace SAF Submission Ingestion Package generated from Vireo submission #11464 on 2017-09-29 at 11:19:24Made available in DSpace on 2017-09-29T17:52:23Z (GMT). No. of bitstreams: 2
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Nanoparticle Enhancement of Natural Killer (NK) Cell-Based Immunotherapy
No full textNatural killer (NK) cells are one of the first lines of defense against infections and malignancies. NK cell-based immunotherapies are emerging as an alternative to T cell-based immunotherapies. Preclinical and clinical studies of NK cell-based immunotherapies have given promising results in the past few decades for hematologic malignancies. Despite these achievements, NK cell-based immunotherapies have limitations, such as limited performance/low therapeutic efficiency in solid tumors, the short lifespan of NK cells, limited specificity of adoptive transfer and genetic modification, NK cell rejection by the patient’s immune system, insignificant infiltration of NK cells into the tumor microenvironment (TME), and the expensive nature of the treatment. Nanotechnology could potentially assist with the activation, proliferation, near-real time imaging, and enhancement of NK cell cytotoxic activity by guiding their function, analyzing their performance in near-real time, and improving immunotherapeutic efficiency. This paper reviews the role of NK cells, their mechanism of action in killing tumor cells, and the receptors which could serve as potential targets for signaling. Specifically, we have reviewed five different areas of nanotechnology that could enhance immunotherapy efficiency: nanoparticle-assisted immunomodulation to enhance NK cell activity, nanoparticles enhancing homing of NK cells, nanoparticle delivery of RNAi to enhance NK cell activity, genetic modulation of NK cells based on nanoparticles, and nanoparticle activation of NKG2D, which is the master regulator of all NK cell responses
Developing Edible Barcodes from Hydrogels: A study on the influence of drying
No full textCounterfeiting of food and pharmaceutical products, albeit a more serious issue in developing countries is, however, omnipresent. Therefore, there is an ever-growing need for anticounterfeiting measures to address this challenge. Currently, the existing overt and covert anticounterfeiting measures are more prevalent on the packaging of such products. While such measures are helpful to a certain extent, they are however, easier to by-pass with re-used authentic packaging, fake barcodes and duplicate product numbering. Furthermore, advanced research and new innovations have indicated that it is also possible to have additional levels of security by incorporating similar measures into or on the product itself. Although these novel anticounterfeiting measures offer a unique opportunity to safeguard the customer’s interest at best, they present certain challenges. Some of these include bio-compatibility of the materials and the need for them to be in compliance with regulatory organizations. However, overcoming these challenges confronts the issue directly. In this work, the approach is to develop a proof of concept of entirely edible barcodes from naturally available and/or food grade materials such as sodium alginate. This study also focusses on the influence of drying on the macroscopic structure of such barcodes. The bar-codes are produced by physically cross-linking the polymer in specific moulds, converting them into a hydrogel barcode in itself. Altogether, this work provides a qualitative under-standing that such a concept can be developed and that the significant structural changes upon drying is not exclusively governed by the concentration of sodium alginate.Chemical Engineerin
Secure Proximity Detection and Verification: Addressing vulnerabilities in IEEE 802.15.4z UWB
No full textWe live in a world where much of our interactions with the environment around us depend on us being physically close to them. For instance, we have proximitybased tokens (e.g., keys and smartcards) for access systems installed at various places such as in cars, at contactless payment terminals, and in electronic passports. Moreover, such systems exist in critical environments like nuclear power plants.Unfortunately, the current systems used to detect proximity between devices and/or users are rife with vulnerabilities. Numerous attacks, such as Relay attack, Preamble Injection attack, Early Detect/Late Commit, and Cicada, exist that let an attacker maliciously alter the measured distance. The research community has proposed several solutions to address these problems and based on their inputs, the IEEE 802.15.4a standard was recently amended. Nevertheless, we show that the newer amendment(i.e., IEEE 802.15.4z) is however not entirely secure and still vulnerable to being exploited.In this work, we evaluate and address the vulnerabilities present in the recently introduced standard,IEEE 802.15.4z amendment for UltraWide Band (UWB). This standard forms the basis of proximity detection in a majority of new devices such as keyfobs for cars, access control systems, smartphones like Samsung S21 and Google Pixel 6, and even medical equipment to monitor patients. First, we mount two attacks, namely the CicadaTF and the Adaptive Injection, against UWB based proximity detection systems. Second, we propose a novel approach to detect the presence of these attacks. We create a real world testbed using DWM3000 ICs mounted on NRF52840devkits to launch the attacks and implement our proposed detection approach. We evaluate the efficacy of our approach in three different environments: an indoor residence, a large outdoor passageway, and an office space. These environments were selected to represent the most commonly used places and were based on the802.15.4a channel models document by IEEE. Our experiment results show that the proposed model can detect the presence of attacks with high accuracy (94%) in all three environments. To the best of our knowledge, this is the first research work that presents a way to detect the presence of such attacks and also to be verified on hardware.Computer Science | Cyber Securit
Feasibility of heavy truck occupant protection measures
No full textNotes: June 2003.Notes: Includes bibliographical references (p. 87-90)Notes: Special reportNational Highway Traffic Safety Administration, Washington, D.CVirginia Polytechnic Institute and State University, Blacksburghttp://deepblue.lib.umich.edu/bitstream/2027.42/1544/2/97646.0001.001.pd
Biodecaffeination of Tea
No full textThis Dissertation / Report is the outcome of investigation carried out by the creator(s) / author(s) at the department/division of Central Food Technological Research Institute (CFTRI), Mysore mentioned below in this page
Studies on Gold Nanoparticle based Bioconjugation for Biosensor Application.
No full textThis Dissertation / Report is the outcome of investigation carried out by the creator(s) / author(s) at the department/division of Central Food Technological Research Institute (CFTRI), Mysore mentioned below in this page
Determinants of Firm Performance: A Subjective Model
No full textThe performance of firm is a relevant construct, in strategic management research, across the globe and frequently it is used as a dependent variable. In spite of its relevance, there is hardly any consensus about its definition, dimensionality and measurement, which limits advances in research. This review article suggests a comprehensive subjective measurement model for performance of firms, based on indicators and findings of earlier research studies. The final subjective model was developed with nine determinants/dimensions, namely, profitability performance, growth performance, market value performance of the firm, customer satisfaction, employee satisfaction, environmental audit performance, corporate governance performance and social performance. It is found that these nine dimensions or determinants cannot be used interchangeably since they represent different aspects of firm performance and different stakeholders of firms have different demands that need to be managed independently. Researchers and practitioners may use the proposed subjective model, in empirical studies, to evaluate the multiple performance of a firm
Nexus between Profitability and Environmental Performance of Indian Firms – An Analysis with Granger Causality
No full textSustainable Development enhances the human life, with good eco facilities. The way to move toward the sustainable development is by giving best solutions to the issues of unbalanced ecological, environmental and economic development. This paper investigates the relationship between the environmental performance and the profitability variables such as ROA, ROE, ROCE, and ROS of the sample firms in India. Granger Causality Test was used to examine bidirectional causality running from Energy Intensity to Profitability of the Firm. The study identified causal relationship that existed among the environmental performance and profitability of the firm. Further, it is found that there was an inverse relationship between ROCE and energy intensity of the firm while direct relationship existed among ROA, ROE, ROS and Energy Intensity. It is suggested that the practitioners, policy makers etc. may adopt the environment friendly technologies and encourage the Indian firms to use more energy efficient technology.
Keywords: Environmental Performance; Firms’ Profitability; Energy Intensity; Causal Effect
JEL Classifications: L25; M14; Q51; Q01; Q
