Simultaneous polymerization and quaternization of 4‐vinyl pyridine

Quantitative polymerization of 4‐vinyl pyridine (4‐VP) and its quaternization has been done simultaneously for the first time in absence of organic solvents. 1, 4‐dibromo‐2‐butene acts as quaternizing agent. The quaternized polymer has been characterized by chemical, thermal and spectral analysis. The mechanistic path involved in the polymerization and quaternization has been elucidated. Particle size, surface area, ion exchange capacity and metal ion binding property were determined. The polymer was found to have pH‐dependent chromate ion binding capacity with high level of selectivity and good antibacterial activity. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Efficiency of high energy electrons to produce polypropylene/natural rubber‐based thermoplastic elastomer

High energy electrons have been used to induce chemical crosslinking in 50/50 blend of polypropylene and natural rubber. The blend morphology was generated during melt mixing and not changed by high energy electron treatment in the solid state at room temperature. The variation of absorbed dose (150–350 kGy) at fixed electron energy (1.5 MeV) brings a dramatic change in the properties of the polymer blend. In addition, the effect of a polyfunctional monomer (PFM) and the absorbed dose on the tensile properties of the polymer blend was investigated. The presence of a PFM led to blends having an elongation at break of about 350% and a tensile strength of nearly 14 MPa after the treatment with a comparatively low dose of 150 kGy. The morphology of the blends was found to be co‐continuous. A plausible mechanistic pathway for the phenomenon leading to enhancement of property has been suggested for better understanding of structure–property‐relationship. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers.     

P2P as a CDN: A new service model for file sharing

Traditional content distribution networks (CDNs), such as Akamai, replicate content at thousands of servers worldwide in an attempt to bring it closer to end users. Recent years have, however, brought a surge of peer-to-peer (p2p) systems that have demonstrated the ability both to help traditional CDN operations and to effectively disseminate content as independent applications. Unfortunately, this p2p surge has created significant problems to network operators by generating large volumes of inter-AS traffic. In this paper, we demonstrate that stepping back and applying traditional CDN design principles to p2p systems can help solve these emerging problems. In particular, focusing on the BitTorrent swarming protocol, we show that our new service model can, in the common case, reduce inter-AS traffic by 45–75%. Moreover, in scenarios when ISPs are shaping inter-AS traffic, it speeds up download times by 60% for the most popular torrents.Our approach bases on disproving the common wisdom that the current peer altruism in p2p systems (BitTorrent in particular) is insufficient. We thus abandon the common approach of deploying novel incentives for cooperation, and focus on designing methods to effectively utilize existing system resources. We show that controlled regional-based content replication, common for the traditional CDN design, can effectively achieve this goal. We implement our system and demonstrate that it effectively scales. Moreover, it is incrementally deployable and brings significant benefits in partial deployment scenarios. ISPs and network regions in which the system gets deployed can resolve their inter-AS traffic problems instantly and autonomously, i.e., without any inter-ISP collaboration and without requiring that the system gets deployed in the entire Internet.     

A chaotic permutation and diffusion based image encryption algorithm for secure communications

In this digital era, a huge amount of digital data is being generated, transmitted, and stored over the network. Images are widely searched, shared and uploaded which make them more vulnerable to the attackers. Therefore, image encryption has become the most widespread form of secure image communication. In recent past, a range of chaotic encryption schemes have been proposed for image encryption which suffers from low key space and high computational overhead. In this paper, the authors have proposed a secure image encryption technique based on 2D Baker’s map. In the proposed scheme a plain image is permuted first, based on a sequence of pseudo random number generated by 2D Baker’s map followed by diffusion process based on XORing. The strength of the proposed scheme is analyzed using the most well-known security test measures like NPCR, MSE, PSNR, UACI, correlation coefficient, Entropy etc. and the results demonstrate that the proposed scheme is resistive to various types of known attacks. The scheme runs on comparatively low computational overhead. Further, the results are compared with existing schemes.

     

Graft copolymerization of nitrile monomers onto sulfonated jute‐cotton blended fabric

Graft copolymerization of nitrile monomers, such as acrylonitrile and methacrylonitrile, onto bleached sulfonated jute‐cotton blended fabric was carried out in an aqueous medium using potassium permanganate as an initiator under the catalytic influence of sulfuric acid in a nitrogen atmosphere. The effect of concentrations of monomer, permanganate, sulfuric acid, reaction time, and reaction temperature on the percent graft yield was studied. The percent graft yield was found to be dependent on the above‐mentioned variables. On the basis of experimental findings, an optimum condition for effective grafting is suggested. As evidence of polymer grafting, some instrumental analyses, such as thermogravimetric analysis, infrared spectroscopy, and X‐ray diffractometry were carried out. Grafting improved the thermal stability, protected from photo‐oxidative degradation, affected dyeability, and had a positive impact on color fastness. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2262–2266, 2003     

Modeling of a process for removal of metal ions by electromigration and electrodeposition

A mathematical model for the removal of impurities of the metal ions of Fe, Ni, and Cu from hard chromium plating solution by electromigration and subsequent electrodeposition has been developed and presented. Experimental data for the metal removal at 45°C and constant cell voltage using o‐phosphoric acid as the catholyte are presented. Up to 36% iron and 29% nickel removal is obtained over about 25 h. The copper removal rate is observed to be approximately four times greater than the rate of nickel removal. The experimental data were found to closely match results predicted from the model developed. The inherent model parameters such as mobility, diffusivity, mass transfer coefficient and metal deposition rate constants were estimated. The calculated values of these parameters are found to be in good agreement with the published data.     

Electrochemical hydrogenation of canola oil using a hydrogen transfer agent

A novel low-temperature process for the electrochemical hydrogenation of canola oil is described. An emulsion of oil and water containing formic acid and a nickel hydrogenation catalyst, placed in the cathode compartment of an electrolysis cell and subjected to an electrical current, underwent hydrogenation at temperatures as low as 45°C. At these low temperatures of hydrogenation, the trans FA content of the hydrogenated canola oil was very low as compared with that of the edible oils hydrogenated by commercial processes using high temperature and high partial pressure of hydrogen gas. Because of its adverse health effects, a high trans FA content in edbile oils is viewed as undesirable. In addition to the commercially available nickel supported on silica, amorphous nickelphosphorus alloys supported on a variety of substrates were also used. Amorphous alloys are generally very corrosion resistant because of the absence of grain boundaries. A mechanism for hydrogenation using the hydrogen transfer agent of formic acid and its continuous regeneration at the cathode was evoked to explain the experimental data.     

Parallel architecture for accelerating affine transform in high-speed imaging systems

Affine transform is widely used in the high speed image processing systems. This transform plays an important role in various high speed applications like Optical quadrature microscopy (OQM), image stabilisation in digital camera and image registration etc. In these applications, transformations of image consume most of the execution time. Hence, for high speed imaging systems, acceleration of Affine transform is very much sought for. In this paper, the pipelined architecture implementation of a proposed inherent parallel algorithm for Affine transform has been presented. The acceleration of the image transformation will help in reducing the processing time of high speed imaging systems. The architecture is mapped in Field programmable gate array (FPGA) and the result shows that the proposed algorithm is almost 4 times faster than the conventional algorithm while retaining the image quality. Using the proposed algorithm, an image of size 1,920 × 1,080 can be transformed with a frame rate of 540 frames per second and the multiplane image synthesis for image stabilisation on the same digital image can be performed with a frame rate of 65 fps.     

Some aspects of deformation behavior of Coarse Multiphase Metallic Materials

The deformation behavior of several single- and two-phase coarse microstructures has been examined using microhardness measurements. It has been found that the strength response of a coarse phase in isolation is distinctly different from its response when it exists in a two-phase system. The second phase alters the mechanical state of the first one andvice versa even in the plastically undeformed condition. This phenomenon is explained in terms of the existence of an appreciable amount of residual stresses in two-phase coarse microstructures. These stresses primarily arise due to the difference in thermal expansion coefficients of the phases. The in- fluence of elastic stress field on microhardness response is shown with a new type of experiment to support the proposed explanation. The present results question the existing expressions for deformation modeling of multiphase materials because of the uncertainties in the estimation of the average strength of the phases in a two-phase system.     

Development of a methodology for the extraction of BSIM3v3.2.2 parameters of Ge-channel MOSFETs and estimation of analog circuit performance

We have developed an algorithm which utilizes model equations for MOSFETs to extract BSIM3v3.2.2 MOSFET model parameters of Ge-channel transistors. The model represents the entire transfer characteristics from sub-threshold to strong inversion regions and the output characteristics from linear to saturation regions thus capturing all the operating bias conditions of gate to source voltage V_GS and drain to source voltage V_DS. For extraction of various BSIM parameters, the model equations are fitted with reported experimental characteristics, and some with TCAD simulation data of Ge MOSFETs for various geometrical dimensions over a wide range of bias conditions. The algorithm used for extracting BSIM3V3.2.2 parameters by fitting BSIM3v3.2.2 model equations with experimental or simulation data is written in MATLAB code. The extracted BSIM model parameters are employed in ADS circuit simulator to reproduce the transfer characteristics of Ge MOSFETs with the same channel length and channel width of 80 nm for both high and low body bias conditions. The characteristics obtained from ADS match well with those obtained from TCAD simulation using SILVACOATLAS thereby ensuring the accuracy of our extraction methodology. The extracted set of BSIM3V3.2.2 parameters is used to generate transfer and output characteristics of Ge channel pMOSFETs at channel length of 70 nm. The extracted value of threshold voltage, bulk mobility and saturation velocity are −0.2 V, 0.18 m²/V.s and 1.2 × 10⁶ m/s, respectively. Our study reveals that various device parameters such as transconductance, intrinsic voltage gain, and cut-off frequency show a maximum value of 677 μS/μm, 2.7, and 63 GHz, respectively.