Thermal and dc Conductivity Behavior of Fly Ash Filled Polyaniline Composites

In this paper temperature dependence of dc conductivity (σ_dc) of emeraldine base form of polyaniline (PANI) and fly ash filled PANI are presented. Samples were prepared by in situ polymerization of aniline using ammonium persulphate as an oxidant and hydrochloric acid as dopant. Fly ash filled PANI composites were prepared by adding 3 gms of fly ash. Thermal characteristics of samples were measured using differential scanning calorimetry. The dc conductivity (σ_dc) of fly ash filled PANI was found to be on the order of 1.63 × 10^?11 s/cm at room temperature, which was lower than that of pure PANI. The activation energies calculated from σ_dc for PANI and the PANI 3 fly ash system were 1.35 and 1.16 eV, respectively. It was found that addition of fly ash to PANI drastically decreased the enthalpy from 2259.2 to 196.6 mJ. the endothermic peak due to the glass transition temperature shifted from 99.8 to 94.6°C. This was attributed to the change in the morphology of the composites on adding fly ash, as observed in the scanning electron micrographs.     

The effect of malformed tiles on tile assemblies within the kinetic tile assembly model

Many different constructions of proofreading tile sets have been proposed in the literature to reduce the effect of deviations from ideal behaviour of the dynamics of the molecular tile self-assembly process. In this paper, we consider the effect on the tile assembly process of a different kind of non-ideality, namely, imperfections in the tiles themselves. We assume a scenario in which some small proportion of the tiles in a tile set are “malformed”. We study, through simulations, the effect of such malformed tiles on the self-assembly process within the kinetic Tile Assembly Model (kTAM). Our simulation results show that some tile set constructions show greater error-resilience in the presence of malformed tiles than others. For example, the 2- and 3-way overlay compact proofreading tile sets of Reif et al. (DNA Computing 10, Lecture Notes in Computer Science, vol 3384. Springer, 2005) are able to handle malformed tiles quite well. On the other hand, the snaked proofreading tile set of Chen and Goel (DNA Computing 10, Lecture Notes in Computer Science, vol 3384. Springer, 2005) fails to form even moderately sized tile assemblies when malformed tiles are present. We show how the Chen–Goel construction may be modified to yield new snaked proofreading tile sets that are resilient not only to errors intrinsic to the assembly process, but also to errors caused by malformed tiles.     

Effect of coupling agent on abrasive wear behaviour of chopped jute fibre-reinforced polypropylene composites

In this paper, studies have been conducted to investigate the abrasive wear behaviour of jute fibre-reinforced polypropylene composites. Effect of addition of maleic anhydride-grafted polypropylene (MA-g-PP)-coupling agent by two different approach, sliding distance and load on abrasive wear performance of jute fibre-PP composites has been determined by using a SUGA abrasion tester. Use of coupling agent gives better wear resistance as compared to without the use of coupling agent. It has also been found that addition of MA-g-PP coupling agent during melt mixing gives better wear resistance as compared to the jute PP composites having MA-g-PP solution-treated jute fibres, which has been explained on the basis of highest thermal stability of jute-PP Composite having melt-mixed MA-g-PP. Abrasive wear performance of the composites has been explained with the help of surface microstructures of worn surfaces.     

Influence of functionalized calcium carbonate nanofillers on the properties of melt-extruded polycarbonate composites

In an effort toward developing better tribological properties of polycarbonate (PC), a reinforcement with calcium carbonate (CaCO₃) nanoparticles (3% by weight), in the size range of 30–60?nm, functionalized using stearic acid, was carried out by melt extrusion method. It was established that scratch resistance of PC/CaCO₃ composites (PCC) improved by 30% in comparison with pure PC. Nevertheless, an assessment of thermal properties using thermogravimetric analysis and differential scanning calorimetry (DSC) indicated an inferior thermal stability of PCC. Thermomechanical properties as obtained from dynamic mechanical analysis revealed an improvement in storage modulus for PCC but loss tangent (tan δ) results indicated lower glass transition (T_g) values in agreement with DSC results. To comprehend the thermal behavior of PCC, degradation kinetics was studied using the model-free method, and it was observed that the presence of organically modified nanoparticles resulted in catalysis of degradation, thus, lowering apparent activation energy (E_α) for PCC at the initial stages of degradation.     

Production planning in the presence of remanufactured spare components: an application in the airline industry

The process of remanufacturing is attractive economically and environmentally for both manufacturers and customers. This paper addresses a problem in the repairable spare parts remanufacturing industry to find the cost-optimal production strategy incorporating reconditioned components. New and reconditioned components are used to carry out replacements in order to honor warranty commitments. Key production decisions, such as when remanufacturing should commence, how long the warranty period should be, and how many returned components should be reconditioned are considered. The availability of reconditioned components and their discounted costs are also incorporated in the mathematical model. The goal is to investigate the interaction between these decisions and their impacts on the manufacturing system and the customer. An application to the remanufacturing of rotable spare parts in the airline industry is presented.     

The Graham-Knowlton Problem Revisited

In the late 60s Graham and Knowlton introduced the WIP (wire identification problem) that affected electricians: match the wires in the ceiling to those in the basement while making the fewest trips. We revisit this problem and study its variants and generalizations; we provide a combinatorial characterization of the solution(s) in terms of an associated hypergraph and obtain nearly tight bounds on the minimum number of trips.