Thermal and thermomechanical behavior of amino functionalized and metal decorated MWCNTs/PMMA nanocomposite films

The homogeneous nanocomposites (NC) films of amino modified and metal decorated multiwall carbon nanotubes (MWCNTs) with polymethylmethacrylate (PMMA) were synthesized through in‐situ free radical polymerization. Silver metal nanohybrids (Ag/MWCNTs) were prepared by two strategies, that is, reduction of metal salt in presence of sodium dodecyl sulfate and in‐situ growth from AgNO₃ aqueous solution. The amino functionalization by ball milling enhanced the dispersion of MWCNT in monomer and produced a new class of radiation resistant NC. These synthesized films were characterized by FTIR, TGA, TEM, EDX, TC, DMA, and optical microscopy to ascertain their structural morphologies, thermal stability, and mechanical strength. Microscopic studies reflect the homogeneous mixing of amino functionalized and metal decorated MWCNTs in polymer matrix contributing in the enhancement of thermal stability, thermo‐mechanical strength, glass transition temperatures, and thermal conductivity of NC even at 0.25 wt% addition of modified nanofiller. The thermal stability of NC film at 0.25 wt% loading was increased around ≂50°C and the raise of thermo‐mechanical properties was observed up to 85% at 100°C in the presence of adsorbed surfactant. Thermal and thermomechanical behavior of pre and post UV/O₃ irradiated NC films has been compared with neat polymer. The results revealed that amino modified nanofiller embedded network in polymer matrix can effectively disperse the radiation and has a dramatic reinforcement effect on the nature of degradation of PMMA matrix. POLYM. COMPOS., 35:1807–1817, 2014. © 2013 Society of Plastics Engineers     

Thresholds and goals for safety performance indicators for nuclear power plants

Performance indicators have found a wide use in the nuclear industry. IAEA developed a safety performance indicators framework for use by NPPs. Karachi Nuclear Power Complex (KNPC) worked, under the auspices of IAEA, on developing guidelines for establishing goals and thresholds, aggregation to higher levels and trend indexes. This paper describes the work done by KNPC on goals and thresholds along with the recommended guidelines.     

Radiation resistant metal decorated MWCNTs/PMMA nanocomposite films with enhanced thermomechanical properties

UV/O₃ radiation and chemical resistant nanocomposite films of functionalized/metal decorated multiwall carbon nanotubes (MWCNTs) with polymethylmethacrylate (PMMA) are synthesized. Silver nanoparticles are decorated on the surface of UV/O₃ functionalized MWCNTs by both reduction and in situ growth from AgNO₃ aqueous solution. Microscopic studies reflect the better dispersion of UV/O₃ functionalized/silver decorated MWCNTs in polymer matrix contributing in enhancement of thermal stability, thermomechanical strength, glass transition temperatures, and thermal conductivity of nanocomposites even at 0.25 wt% MWCNTs additions. The thermal stability of nanocomposite film (0.25 wt% loading), prepared by using a surfactant (Sodium dodecyl sulfate) is increased to about 27°C while the thermomechanical properties are raised up to 76% at 100°C. Thermal and thermomechanical behavior of pre‐ and post‐UV/O₃ irradiated nanocomposite films are compared with neat polymer. The results reveal that UV/O₃ functionalized MWCNTs can effectively disperse the radiation and have a dramatic reinforcement effect on the nature of the degradation of PMMA matrix. POLYM. COMPOS., 36:969–978, 2014. © 2014 Society of Plastics Engineers     

Aggregation of safety performance indicators to higher-level indicators

In the hierarchical structure of IAEA safety performance indicators (SPIs) the top level is operational safety performance. Safety performance cannot be measured directly. Aggregation is a process by which the indices of the lower-level indicators are combined to get the numerical index for the next higher-level indicator. Hence, with the help of aggregation, the numerical index can be obtained for safety performance of a nuclear power plant. Karachi Nuclear Power Complex (KNPC) worked, under the auspices of IAEA, on developing guidelines for establishing goals and thresholds, aggregation to higher-level indicators and trend indices of SPIs. This paper presents the work done by KNPC on aggregation to higher-level indicators.     

Improving tantalum's oxidation resistance by Al+ ion implantation

Tantalum was implanted with 180 keV Al⁺ ions to fluences up to 3×10¹⁸ Al⁺/cm². Subsequent microchemical and microstructural observations showed that an amorphous layer covered the surface and extended to depths near 3000 Å for fluences above 2.4×10¹⁸ Al⁺/cm². The layer, comprised of ～70 at. pet Al and ～30 at. pet Ta, crystallized at temperatures above 500°C. Oxidation measurements, performed in one atmosphere of air and at temperatures below 600°C, showed that the layer stopped oxidation of the implanted tantalum, while unimplanted tantalum oxidized rapidly. The protection provided by the implantation deteriorated somewhat by temperatures near 735°C but still reduced the oxidation rate by a factor of 5. The deterioration is caused by localized rupturing of the implanted layer and the resulting oxidation of the underlying tantalum. At 910°C, the implanted tantalum oxidized almost as rapidly as unimplanted tantalum.     

Deposition of bismuth sulfide and aluminum doped bismuth sulfide thin films for photovoltaic applications

Journal of Materials Science: Materials in Electronics - Binary bismuth sulfide (Bi2S3) and ternary aluminum-doped bismuth sulfide (Al@Bi2S3) thin films were prepared by the chemical bath...     

Real-Time Violent Action Recognition Using Key Frames Extraction and Deep Learning

Violence recognition is crucial because of its applications in activities related to security and law enforcement. Existing semi-automated systems have issues such as tedious manual surveillances, which causes human errors and makes these systems less effective. Several approaches have been proposed using trajectory-based, non-object-centric, and deep-learning-based methods. Previous studies have shown that deep learning techniques attain higher accuracy and lower error rates than those of other methods. However, the their performance must be improved. This study explores the state-of-the-art deep learning architecture of convolutional neural networks (CNNs) and inception V4 to detect and recognize violence using video data. In the proposed framework, the keyframe extraction technique eliminates duplicate consecutive frames. This keyframing phase reduces the training data size and hence decreases the computational cost by avoiding duplicate frames. For feature selection and classification tasks, the applied sequential CNN uses one kernel size, whereas the inception v4 CNN uses multiple kernels for different layers of the architecture. For empirical analysis, four widely used standard datasets are used with diverse activities. The results confirm that the proposed approach attains 98% accuracy, reduces the computational cost, and outperforms the existing techniques of violence detection and recognition.     

Implementation of a high-accuracy phase unwrapping algorithm using parallel-hybrid programming approach for displacement sensing using self-mixing interferometry

The Journal of Supercomputing - Phase unwrapping is an integral part of multiple algorithms with diverse applications. Detailed phase unwrapping is also necessary for achieving high-accuracy metric...