383 research outputs found
Graphene-Based Surface Heater for De-Icing Applications
No full textGraphene-based de-icing composites are of great interest due to incredible thermal, electrical and mechanical properties of graphene. Moreover, current technologies possess a number of challenges such as expensive, high power consumption, limited life time and adding extra weight to the composite. Here, we report a scalable process of making highly conductive graphene-based (coated) glass fibre rovings for de-icing application. We also use a scalable process of making graphene-based conductive ink by microfluidic exfoliation technique. The glass fibre roving is then coated with graphene-based conductive inks using a dip-dry-cure technique which could potentially be scaled up into an industrial manufacturing unit. The graphene-coated glass roving demonstrates low resistances (~1.7 Ω/cm) and can heat up rapidly to a required temperature using a relatively lower voltage. We integrate these graphene-coated glass rovings into a vacuum infused epoxy-glass fabric composite and demonstrate the potential use of as prepared graphene-based composite for de-icing application
Ultra-High Performance of Nano-Engineered Graphene-Based Natural Jute Fiber Composites
No full textNatural fibers composites are considered as sustainable alternative to synthetic composites due to their environmental and economic benefits. However, they suffer from poor mechanical and interfacial properties due to a random fiber orientation and weak fiber-matrix interface. Here we report nano-engineered graphene-based natural jute fiber preforms with a new fiber architecture (NFA) which significantly improves their mechanical properties and performances. Our graphene-based NFA of jute fiber perform enhances Young modulus of jute-epoxy composites by ~324% and tensile strength by ~110% more than untreated jute fiber composites, by arranging fibers in parallel direction through individualisation and nano surface engineering with graphene derivatives. This could potentially lead to manufacturing of high performance natural alternatives to synthetic composites in various stiffness driven high performance applications
High Performance Graphene-Based Natural Fibre Composites
No full textNatural fibre composites are attracting significant interest due to their potential for replacing synthetic composites at lower cost with improved environmental sustainability. However, natural fibre composites suffer from poor mechanical and interfacial properties. Here we report coating of graphene oxide (GO) and graphene flakes (G) onto natural jute fibres in order to improve mechanical and interfacial properties.The coating of graphene materials onto jute fibres enhanced interfacial shear strength by ~236% and tensile strength by ~96% more than untreated fibres by forming either bonding (GO) or mechanical inter-locking (G) between fibres and graphene-based flakes.This could lead to manufacturing of high performance and environmental friendly natural fibre composites that can potentially replace synthetic composites in numerous applications such as the automotive industry, naval vessels, household products and even in the aerospace industry
Robust decentralized authentication for public keys and geographic location:
No full textAuthentication has traditionally been done either in a decentralized manner with human assistance or automatically through a centralized security infrastructure. In the security infrastructure approach, a central trusted authority takes on the responsibility of authenticating participants within its domain of control. While the security infrastructure approach works well in traditional organizations, it does not address the needs of open membership systems.
We propose automatic decentralized authentication mechanisms for peer-to-peer systems, email systems, and ad-hoc networks. Our byzantine fault tolerant public-key authentication protocol (BPKA) provides decentralized authentication to peer-to-peer systems with honest majority. Authentication is done over an insecure asynchronous network without using trusted third parties or human input. We also authenticate public keys in the email environment through our social-group key authentication protocol (SGKA). The protocol provides end-to-end authentication at the email client without using infrastructure or centralized authorities. Finally, location authentication in ad-hoc networks is proposed through our geographical secure path routing protocol (GSPR). The protocol authenticates geographic locations of anonymous nodes in order to provide location authentication and anonymity simultaneously.Ph.D.Includes bibliographical references (p. 121o-128)by Vivek Patha
Conservational Analysis of Influenza A Virus RNA-dependent RNA Polymerase
No full textCompeting Interests: The authors have declared that no competing interests exist. Copyright: 2015 Darapaneni V et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. *Correspondence to: Vivek Darapaneni, Department of virology and computational biochemistry, Sake
Debt maturity and firm performance : a panel study of Indian companies
No full textEconomic policy makers traditionally hold the view that, because of imperfections in capital markets, a shortage of long-term finance acts as a barrier to industrial performance and growth. Long term finance is thought to allow firms to invest in more productive technologies, even when they do not produce immediate payoffs, without fear of premature liquidation. As a result, special state-supported term-lending institutions have been established, especially in developing countries. But some believe that short-term finance may offer better incentives because it allows suppliers of finance to monitor and control firms more effectively, thus improving the firms'performance. The authors empirically investigate the determinants and consequences of the term structure of debt. Using a rich panel of data on privately owned companies in India, they also examine the influence of debt maturity structures on those firm's performance, especially on productivity. The results are not conclusive, but seem to support conventional beliefs about the importance of long term finance to firm performance. Heavy leveraging, however, has a strong negative impact on productivity. They base their econometric evidence on estimates of a maturity equation and of a production function augmented by financial variables. The data on which these results are based have been generated by a financial system in which there is little competition, in which state-owned financial institutions are not guided by the profit motive and have no control over interest rates, so one cannot say whether short term finance would have been more beneficial in a less regulated system. Moreover, by the end of the 1980s, the capital base of India's government-owned financial institutions had been severely eroded and they carried a heavy burden of nonperforming assets. This means that the benefits of long term finance must be weighed against the costs.Banks&Banking Reform,Financial Intermediation,Economic Theory&Research,Municipal Financial Management,Environmental Economics&Policies
Lattice approximation in the stochastic quantization of ([phi]4̳)2̳fields
No full textCaption title. "August 1988." On the title page, the bracketed word in the title appears as the Greek mathematical symbol representing [phi], the numeral four preceded by a double underscore appears as superscript, and the numeral two preceded by a double underscore appears as subscript.Includes bibliographical references.The research of the second author was supported in part by the U.S. Army Research Office, contract DAAL03-86-K-0171 The research of the second author was supported in part by the Air Force Office of Scientific Research under contract AFOSR-85-0227by Vivek S. Borkar, Sanjoy K. Mitter
On a 3GPP ray-based spatial channel model for MIMO system emulation: implementation and evaluation
No full textThe mitigation of random effects in a wireless communication channel is a problem considered for many years. In the present day context, given the ever increasing need for, and growth of, bandwidth intensive applications like streaming wireless HD video on fast moving user equipment (UEs, i.e., user communication devices), this issue has intensified from being a theoretical pursuit to a must-be-solved practical endeavor. In that regard, the ability to accurately model the outdoor (or indoor) propagation conditions in a laboratory setting becomes vital to validating state-of-the-art wireless standards and the devices that derive from them. Laboratory-based analysis is a significant catalyst in reducing the time-to-market for telecom equipment manufacturers. Modeling a wireless channel has been a topic under quite a bit of study. This has progressed from the Jakes model developed for single antenna systems to the correlation and ray-based models used for multiple antenna systems. The models prescribed by the 3rd Generation Partnership Project (3GPP) in its standards, like the ray-based model, aim to realistically reproduce channel environments in software and hardware, by incorporating all the variables that characterize any particular fading scenario. In this thesis, the technical report produced by 3GPP detailing the Spatial Channel Modeling (SCM) for multiple input multiple output (MIMO) simulations is followed closely as a basis for developing a real-time channel emulator on a National Instruments (NI) based Real Time (RT) Platform. First, a general purpose channel emulator is described in terms of its structure and functionality and currently known channel models are briefly investigated. Next, the spatial channel model in the standard is described in detail along with the reasons for choosing to use it in the thesis. All the parameters involved are defined, and the formula for constructing the channel is carefully investigated. Next, the channel emulator built on the National Instruments LabVIEW platform is described along with both the changes and modifications made to the design parameters so as to adapt it to the operating constraints of the RT platform. The spatial and temporal characteristics of the model are also described and plotted. Finally, the model is tested for reliability by methodically changing the various channel parameters and observing their effects on an Orthogonal Frequency Division Multiplexing (OFDM) test vector by generating BER performance plots in MATLAB. Diversity schemes are also employed to improve rate performance.M.S.Includes bibliographical referencesby Sabarish Karthik Vivek Sarath
Review essay: Vivek Chibber, Postcolonial Theory and the Specter of Capital
No full textThye article is a review essay of Vivek Chibber's recent book, Postcolonial Theory and the Specter of Capital. The publication of this book has raised lively and highly polemical debates, which are also reviewed in the artifcle. More generally, the essay discusses at length the development and the achievements of subaltern studies, testing Chibber's critique and dismissal of this important strand of critical theory. At the center of the discussion is the relation between subaltern (and more generally postcolonial) studies and historical as well as contemporary capitalism. The author discusses this question as well as the related problem of the relation between capital and universalism, proposing ananalytical framework which radically differes from the one elaborated by Chibber
- …
