Effect of synthesis parameters on the electrical conductivity of polypyrrole-coated poly(ethylene terephthalate) fabrics

The effects of pyrrole, anthraquinone-2-sulphonic acid (AQSA) and iron(III) chloride (FeCl3) concentrations, reaction time and temperature on the electrical conductivity of polypyrrole (PPy) - coated poly(ethylene terephthalate) (PET) fabrics were investigated. With an increase in both the AQSA and FeCl3 concentrations, resistivity decreased to a point beyond which higher concentrations led to increased surface resistivity. Erosion of the polymer coating, in dynamic synthesis from continual abrasion, manifested as an exponential increase in the resistance of the coated textile substrate. This was not encountered in static synthesis conditions. Temperature affected the degree of surface and bulk polymerisation. The effect of polymerisation temperature on conductivity was negligible. Conductive polymer coating on textiles through chemical polymerisation enabled a smooth coherent film to encase individual fibres, which did not affect the tactile properties of the host substrate. The optimum FeCl3/pyrrole and AQSA FeCl3/pyrrole molar ratios were found to be 2.22 and 0.40 respectively.

Effect of weight reduction pre-treatment on the electrical and thermal properties of polypyrrole coated woven polyester fabrics

Weight reduction increased the amount of deposited polypyrrole (PPy) on the polyester (PET) fiber surface, leading to a considerable decrease in electrical resistance and improved heat generation capacity for the PPy coated PET fabrics. Application of dc voltages to an insulated roll of PPy-coated fabric increased the temperature to about 90 °C. This showed the suitability of these fabrics for heating applications. The optimum PPy deposition of about 2.8% was obtained in samples weight reduced by aqueous sodium hydroxide treatment. AFM images revealed a smooth surface morphology of the untreated fiber whereas the treated fiber had a high surface roughness.

Efficacy of neuromuscular electrical stimulation in improving ankle kinetics during walking in children with cerebral palsy

Neuromuscular electrical stimulation (NMES) applied to the triceps surae muscle is claimed to be effective in improving gait in children with cerebral palsy. The main aim of this study was to determine the effect of NMES on the triceps surae muscle in improving the gait and function of children with cerebral palsy. Twelve children with spastic diplegia or hemiplegia were recruited and randomly assigned to the two experimental groups. The period of the study was 8 weeks (2-4-2 week design). The initial 2 weeks was the control period, in which usual treatment was given to both groups of patients with a pre- and post-treatment assessment. The middle 4 weeks was the experimental period, in which the Treadmill+NMES group received NMES plus treadmill walking training and the Treadmill group underwent treadmill walking training only. Assessment was performed at 2-week intervals. The final 2 weeks was the carryover period, in which treatment to be tested was stopped and reassessment performed again at the end of week 8. An additional treatment and post-treatment assessment were given at weeks 2, 4 and 6 to test for the immediate effect of treatment. Altogether, eight repeated measures with three-dimensional gait analysis and five clinical measurements using the gross motor function measure (GMFM) were performed. Kinetic changes in ankle moment quotient (AMQ) and ankle power quotient (APQ) were not significant either immediately or cumulatively in both groups. Improvement in trend was observed in both groups immediately but not cumulatively. Using the GMFM, functional changes were detected in standing (GMST, p < 0.001) and in walking (GMWK, p = 0.003) using a 'time' comparison. Significant interaction was also detected in GMWK using 'treatment by time' (p = 0.035). The difference between the two groups was not significant on 'treatment' comparison of both GMST and GMWK. Both groups showed improvement in GMST and GMWK cumulatively but there was no difference between the two groups. The effects in both groups could be carried over to 2 weeks after interventions stopped. Both the Treadmill+NMES and Treadmill groups showed improvement in functional outcomes. The trend in the changes of the GMFM score suggested that improvements were greater in the Treadmill+NMES group. There was also a trend showing some immediate improvement in AMQ and APQ.

Design of electrical infrastructure at container terminal and 'net metering'

Net metering is generally a consumer-based incentive for renewable sources such as wind or solar power systems also referred to as dasiacogenerationdasia. It is still a grey area for container terminals with large electric machines, such as quay cranes, automatic stacking cranes, that can operate in the regenerative mode and export electric energy to the grid. With actual measured electrical data presented for discussion, this paper provides information for the readers to provide a better understanding of their access to net metering, ultilizing their electrical equipment capabilities and be informed for their next negotiation with the power supply company.

Decay of electrical conductivity in p-toluene sulfonate doped polypyrrole films

Long term performance of conductivity of p-toluene sulfonic acid (pTSA) doped electrochemically synthesized polypyrrole (PPy) films was estimated from accelerated aging studies between 80 °C and 120 °C. Conductivity decay experiments indicated that overall aging behavior of PPy films deviated from first order kinetics at prolonged aging times at elevated temperatures. However, an approximate value for the activation energy of the conductivity decay of PPy was calculated as E=47.4 kJ/mol, enabling an estimate of a rate constant of k=8.35×10⁻⁶/min at 20 °C. The rate of decrease of conductivity was not only temperature dependent but also influenced by the dopant concentration. A concentration of 0.005 M pTSA in the electrolyte resulted in a conductive film and when this film was exposed to 120 °C for a period of 40 h, the conductivity decayed to about 1/20 of its original value. The concentration of pTSA was increased to 0.05 mol/l and when the resulting film was aged in the same way, it showed a decrease in the conductivity to about 1/3 of its original value. Both microwave transmission and dc conductivity data revealed that highly doped films were considerably more electrically stable than lightly doped films. The dopant had a preserving effect on the electrical properties of PPy.

Improved electrical efficiency by active cooling of building integrated photovoltaic panels

The electrical efficiency of photovoltaic devices can be directly related to the temperature of the photovoltaic cells.Tn this study a BIPVT solar collector was analysed and key parameters affecting its electrical efficiency were identified.

Analysis of twelve electrical and electronics engineering programs

This paper investigates undergraduate programs in electrical and electronics engineering offered by twelve universities in Australia, Asia, Europe, and America. The investigation focuses on the structure and content of the programs, and the contact hour and assessment of the subjects involved in the programs. The investigation is carried out in four stages: selection of universities, collection of data, analysis of data, and formulation of outcomes. A list of subjects is created based on the content of the programs. The average percentage coverage of each subject in the twelve programs is calculated. The subjects are then grouped into nine program components. The average percentage coverage of each component per university is calculated. For each component, the total number of contact hours for lecture, tutorial, and practical is calculated. Also, the average percentage of four assessment methods for each component is found. Discussions on the outcome of the investigation are presented.

Spatial modeling of electrical conductivity with neural network

Many policy decisions for agricultural management in the coastal region closely depend on the extent of intrusion of sea water. In this study, Artificial Neural Network (ANN) is used to model the spatial variation of Electrical Conductivity to determine the extent of sea water intrusion in the coastal area of Brisbane, Australia. Quarterly EC data obtained from the observation (monitoring) wells located along the coast is used for training ANN architecture. The study demonstrates that ANN is able to model the spatial variation of EC with very good accuracy (even with very less training records) when some spatial information is used as one of the inputs in the network training. The results considerable improvement when compared with the network trained without the distance information.

Possible electrical double-layer contribution to the equilibrium thickness of intergranular Glass films in polycrystalline ceramics

The plausibility of the entropic repulsion of electrical double layers acting to stabilize an equilibrium thickness of intergranular glass films in polycrystalline ceramics is explored. Estimates of the screening length, surface potential, and surface charge required to provide a repulsive force sufficiently large to balance the attractive van der Waals and capillary forces for observable thicknesses of intergranular film are calculated and do not appear to be beyond possibility. However, it has yet to be established whether crystalline particles in a liquid-phase sintering medium possess an electrical double layer at high temperatures. If they do, such a surface charge layer may well have important consequences not only for liquid-phase sintering but also for high-frequency electrical properties and microwave sintering of ceramics containing a liquid phase.

Dynamics of interactions involving deformable drops : hydrodynamic dimpling under attractive and repulsive electrical double layer interactions

A model developed previously to analyze force measurements between two deformable droplets in the atomic force microscope [Langmuir 2005, 21, 2912-2922] is used to model the drainage of an aqueous film between a mica plate and a deformable mercury drop for both repulsive and attractive electrical double-layer interactions between the mica and the mercury. The predictions of the model are compared with previously published data [Faraday Discuss. 2003, 123, 193-206] on the evolution of the aqueous film whose thickness has been measured with subnanometer precision. Excellent agreement is found between theoretical results and experimental data. This supports the assumptions made in the model which include no-slip boundary conditions at both interfaces. Furthermore, the successful fit attests to the utility of the model as a tool to explore details of the drainage mechanisms of nanometer-thick films in which fluid flow, surface deformations, and colloidal forces are all involved. One interesting result is that the model can predict the time at which the aqueous film collapses when attractive mica-mercury forces are present without the need to invoke capillary waves or other local instabilities of the mercury/electrolyte interface.

Transient responses of a wetting film to mechanical and electrical perturbations

This article reports real-time observations and detailed modeling of the transient response of thin aqueous films bounded by a deformable surface to external mechanical and electrical perturbations. Such films, tens to hundreds of nanometers thick, are confined between a molecularly smooth mica plate and a deformable mercury/electrolyte interface on a protuberant drop at a sealed capillary tube. When the mercury is negatively charged, the water forms a wetting film on mica, stabilized by electrical double layer forces. Mechanical perturbations are produced by driving the mica plate toward or by retracting the mica plate from the mercury surface. Electrical perturbations are applied to change the electrical double layer interaction between the mica and the mercury by imposing a step change of the bias voltage between the mercury and the bulk electrolyte. A theoretical model has been developed that can account for these observations quantitatively. Comparison between experiments and theory indicates that a no-slip hydrodynamic boundary condition holds at the molecularly smooth mica/electrolyte surface and at the deformable mercury/electrolyte interface. An analysis of the transient response based on the model elucidates the complex interplay between disjoining pressure, hydrodynamic forces, and surface deformations. This study also provides insight into the mechanism and process of droplet coalescence and reveals a novel, counterintuitive mechanism that can lead to film instability and collapse when an attempt is made to thicken the film by pulling the bounding mercury and mica phases apart.