A decentralised multi-agent approach to enhance the stability of smart microgrids with renewable energy

This paper presents the impact of large penetration of wind power on the transient stability through a dynamic evaluation of the critical clearing times (CCTs) by using intelligent agent-based approach. A decentralised multi-agent-based framework is developed, where agents represent a number of physical device models to form a complex infrastructure for computation and communication. They enable the dynamic flow of information and energy for the interaction between the physical processes and their activities. These agents dynamically adapt online measurements and use the CCT information for relay coordination to improve the transient stability of power systems. Simulations are carried out on a smart microgrid system for faults at increasing wind power penetration levels and the improvement in transient stability using the proposed agent-based framework is demonstrated.     

Wavelet-enhanced bayesian classification of surface nanostructures observed in pentacene thin films

In recent years, the wavelet transform has proven to be an extremely powerful image-processing tool. Here, we have developed a wavelet-enhanced Bayesian methodology to analyze the AFM images of organic crystals, such as pentacene, using the Haar wavelet transform. This methodology segments and identifies structures in AFM data and extracts quantitative information such as grain size, perimeter, and orientation. This methodology relies on a Naïve Bayesian classification system, which determines whether each data point corresponds to a peak or a valley with a finite statistical probability based on analysis of a synthetic teaching image. In this work, we apply this technique to AFM images of organic crystal films deposited on three different substrates.     

Effect of torsional oscillations on the stress-strain behavior of Al-5 wt% Mg alloy

The microstructure and mechanical properties of a precipitation hardenable Al-5 wt% Mg alloy subjected to low frequency torsional oscillations and aging treatments are reported in the present work. The stress-strain response was examined at different frequencies (1.53-3.3 Hz) and at constant shear strain amplitude (φ = 5.69 × 10⁻⁴). An excessive in the softening was observed by increasing both frequency of the applied oscillations and deformation temperature. The change in the hardening and softening parameters of stress-strain relations was explained in view of spinodal decomposition in Al-Mg systems. The mean value of activation energy was found to be equal to that quoted for precipitate-dislocation intersection.     

Strength estimation of unisothermally cured concretes with matrices

A new matrix method was developed for estimating the strength of in situ concrete exposed to unisothermal curing conditions. The model considers effect of various curing temperatures occurred at different ages of concrete on strength development of concrete. The cross-over effects on later age concrete strength due to hot or cold weather conditions in early-ages of concrete were also considered. The model ensures precise strength estimations with error percentages below 7%. The time required for form removal of concrete can be determined by the method.     

LC-MS/MS-based determination of chloramphenicol,thiamphenicol, florfenicol and florfenicol amine in poultry meat from the Punjab-Pakistan

A simple, reliable and sensitive liquid chromatography-tandem mass spectrometry-based confirmatory method was redeveloped and validated for the simultaneous determination of chloramphenicol, thiamphenicol, florfenicol and florfenicol amine in chicken muscles. The analytes were extracted from minced chicken muscle with acetonitrile and ammoniated water mixture. A second extraction with ethyl acetate was followed by evaporation and dissolution of the residue in ammoniated methanol before defatting with n-hexane. Finally, the extract was further cleaned up by dispersive solid phase extraction using C-18 end-capped dispersive material. The validation protocol was adapted from the European Commission Decision 2002/657/EC and all the performance characteristics were successfully satisfied. The recoveries of all the analytes were found to be in the range of 86.4–108.1% and the precision values, within day and between days, ranged from 2.7% to 11% and 4.4% to 16.3%, respectively. The method was tested in various incurred samples and applied to analyse a wide range of random poultry market samples (n = 120) collected from three cities of the Punjab, Pakistan. Chloramphenicol and florfenicol residues were detected at low levels in less than 11% of the samples. Chloramphenicol was detected only in 4 samples with the concentration range of 0.17–0.477 µg kg^–1, whereas the levels of florfenicol/florfenicol amine residues detected in 9 samples ranged from 8.7 to 32.8 µg kg^–1. Moreover, most of the florfenicol residues were identified as tissue bound, extractable only after strong acid hydrolysis.     

Assessing the role of turbulence-radiation interactions in hydrogen-enriched oxy-methane flames

Statistical analysis of scalar data obtained from single-shot laser measurements in four turbulent oxy-fuel flames were carried out to develop a functional relationship for the temperature self-correlation (TSC) term for use in Turbulence Radiation Interaction (TRI) models. The developed relationship was found to be invariant with the hydrogen enrichment in the fuel, fuel jet Reynolds numbers and correlated reasonably well with the root-mean-square of temperature (T_rms). The TSC and the absorption-coefficient temperature correlation (ATC) were both modeled in terms of T_rms and employed as add-on functions in time-averaged flame simulations. Including the effects of TRI enhanced the radiant fraction by 40% and reduced outlet CO concentrations by 30% across all flames. Further, there was significant flame absorption due to the high concentrations of radiatively participating gases that would deem optically thin radiation approximations in these flames to be erroneous.     

Intermittent Audio Failure Analysis of a Remote Speaker-Microphone for a Two-Way Radio

This paper presents a case study of an intermittent audio failure analysis of a remote speaker-microphone module for a two-way radio. A root cause analysis was undertaken to identify probable causes of the intermittent failure, followed by a series of experiments to determine the strength and the intermittent audio failure load of cable components and the fully assembled cable. The combined experimental and finite element results demonstrated that the main contributor of the intermittent audio failure was the micro surface cracks on the copper conductor strands. In addition, the combination of the component materials and design of the cable have also contributed to the non-uniform state of residual stress induced in the copper conductors which have reduced the ability of the copper conductors to withstand the normal handling load under the influence of micro surface cracks.