Indian Institute of Technology Kharagpur

About: Indian Institute of Technology Kharagpur is a education organization based out in Kharagpur, India. It is known for research contribution in the topics: Natural rubber & Dielectric. The organization has 16887 authors who have published 38658 publications receiving 714526 citations.

An effective strategy to enhance mechanical, electrical, and electromagnetic shielding effectiveness of chlorinated polyethylene-carbon nanofiber nanocomposites

Abstract: Chlorinated polyethylene (CPE) filled with functionalized heat treated carbon nanofiber (CNF) nanocomposites were prepared using two different techniques like melt mixing and solution cum melt mixing. A better dispersion of CNFs in nanocomposite was achieved by solution cum melt mixing compared to only melt mixing process. The effect of mechanical, electrical conductivity (σ), and electromagnetic interference shielding effectiveness (EMI SE) were studied. Nanocomposites prepared by solution cum melt mixing process showed higher mechanical properties, electrical conductivity (σ), and electromagnetic interference shielding effectiveness (EMI SE) compared to that of melt mixing process. 1 wt% CNFs filled nanocomposites prepared by the solution followed by melt mixing showed 124% higher tensile strength whereas at the same percentage of CNFs, melt processed nanocomposite exhibited 58% higher in tensile strength compared to neat CPE. The EMI SE and σ of both types of nanocomposites were increased with increasing CNFs loading. At 10 wt% CNFs loading, solution cum melt processed nanocomposite showed EMI SE 24 dB; whereas at the same wt% of CNFs loading, melt processed nanocomposite showed 22 dB. Thermogravimetric analysis was carried to investigate the thermal stability of CPE/CNF nanocomposites.

Result Pattern Hiding Searchable Encryption for Conjunctive Queries

Abstract: The recently proposed Oblivious Cross-Tags (OXT) protocol (CRYPTO 2013) has broken new ground in designing efficient searchable symmetric encryption (SSE) protocol with support for conjunctive keyword search in a single-writer single-reader framework. While the OXT protocol offers high performance by adopting a number of specialised data-structures, it also trades-off security by leaking 'partial' database information to the server. Recent attacks have exploited similar partial information leakage to breach database confidentiality. Consequently, it is an open problem to design SSE protocols that plug such leakages while retaining similar efficiency. In this paper, we propose a new SSE protocol, called Hidden Cross-Tags (HXT), that removes 'Keyword Pair Result Pattern' (KPRP) leakage for conjunctive keyword search. We avoid this leakage by adopting two additional cryptographic primitives - Hidden Vector Encryption (HVE) and probabilistic (Bloom filter) indexing into the HXT protocol. We propose a 'lightweight' HVE scheme that only uses efficient symmetric-key building blocks, and entirely avoids elliptic curve-based operations. At the same time, it affords selective simulation-security against an unbounded number of secret-key queries. Adopting this efficient HVE scheme, the overall practical storage and computational overheads of HXT over OXT are relatively small (no more than 10% for two keywords query, and 21% for six keywords query), while providing a higher level of security.

α MnMoO4/graphene hybrid composite: high energy density supercapacitor electrode material

Abstract: A unique and cost effective hydrothermal procedure has been carried out for the synthesis of hexahedron shaped α MnMoO4 and its hybrid composite with graphene using three different weight percentages of graphene. Characterization techniques, such as XRD, Raman and FTIR analysis, established the phase and formation of the composite. The electrochemical characterization of the pseudocapacitive MnMoO4 and the MnMoO4/graphene composites in 1 M Na2SO4 displayed highest specific capacitances of 234 F g−1 and 364 F g−1, respectively at a current density of 2 A g−1. Unlike many other pseudocapacitive electrode materials our prepared materials responded in a wide range of working potentials of (−)1 V to (+)1 V, which indeed resulted in a high energy density without substantial loss of power density. The highest energy densities of 130 Wh kg−1 and 202.2 Wh kg−1 were achieved, respectively for the MnMoO4 and the MnMoO4/graphene composite at a constant power delivery rate of 2000 W kg−1. The synergistic effect of the graphene with the pseudocapacitive MnMoO4 caused an increased cycle stability of 88% specific capacitance retention after 1000 consecutive charge discharge cycles at 8 A g−1 constant current density, which was higher than the virgin MnMoO4 with 84% specific capacitance retention.