Aqeel Ahmad Taimoor

Virtualization of the process control laboratory using ASPEN HYSYS

Undergraduate chemical engineering students should be trained differently from other disciplines in control theory. ASPEN HYSYS provides basic modules for the unit operation with dynamics that can be used in elucidating the intended principles to control students virtually, which are not available in MATLAB (SIMULINK). A total of six workshops are designed. The laboratory course starts by familiarizing students to dynamic feature of the commercial software. Students are then introduced to operational safety aspects, by solving a runaway CSTR model. Importance of transfer functions is elucidated as an approach to integrate with different other electrical devices. Frequency response analysis is then presented using the transfer function to visualize instability. Two experiments are designed for PID controller so that students can envisage the affect of tuning parameters on absolute integrated error, offset, and regulation of manipulated variable. Different tuning methods and their objectives are also explained. The comparison between SIMULINK and HYSYS simulation is discussed. Modules are provided as supplement material. Surveys and direct assessment tools evaluate students understanding of the course. The results are compared with the previous session using SIMULINK as laboratory tool presenting higher satisfaction with HYSYS.

Effect of micro- to nanosize inclusions upon the thermal conductivity of powdered composites with high and low interface resistance

Materials for thermal management application require better control over the thermophysical properties, which has largely been achieved by fabricating powdered composite. There are, however, several factors like filler volume fraction, shape morphology, inclusion size, and interfacial thermal resistance that limit the effective properties of the medium. This paper presents a methodology to estimate the effective thermal conductivity of powdered composites where the filler material is more conductive than the matrix. Only a few theoretical models, such as Hasselman and Johnson (HJ) model, include the effect of interfacial resistance in their formulation. Nevertheless, HJ model does not specify the nature of the interfacial thermal resistance. Although Sevostianov and Kachanov (SK) method takes care of interface thickness, they, on the other hand, have not taken into account the interfacial resistance due to atomic imperfections. In the present work, HJ model has been modified using SK method and the results were compared with experimental ones from the literature. It has been found that the effect of interfacial resistance is significant in highly resistive medium at microscale compared to nanoscale, such as Cu/diamond system, while, in a highly conductive medium, like bakelite/graphite system, the effect of shape factor is more significant than interfacial thermal resistance.

Deciphering lead and cadmium stripping peaks for porous antimony deposited electrodes

Abstract Cadmium and lead are generally taken as model heavy metal ions in water to scale the detection limit of various electrode sensors, using electrochemical sensing techniques. These ions interact with the electrochemically deposited antimony electrodes depending on the diffusion limitations. The phenomenon acts differently for the in-situ and ex-situ deposition as well as for porous and non-porous electrodes. A method has been adopted in this study to discourage the stripping and deposition of the working ions (antimony) to understand the principle of heavy metal ion detection. X-ray photoelectron spectroscopy (XPS) technique was used to establish the interaction between the working and dissolved ions. In addition to the distinct peaks for each analyte, researchers also observed a shoulder peak. A possible reason for the presence of this peak was provided. Different electrochemical tests were performed to ascertain the theory on the basis of the experimental observations.

Fatigue Delamination Crack Growth in GFRP Composite Laminates: Mathematical Modelling and FE Simulation

Glass fibre-reinforced plastic (GFRP) composite laminates are used in many industries due to their excellent mechanical and thermal properties. However, these materials are prone to the initiation and propagation of delamination crack growth between different plies forming the laminate. The crack propagation may ultimately result in the failure of GFRP laminates as structural parts. In this research, a comprehensive mathematical model is presented to study the delamination crack growth in GFRP composite laminates under fatigue loading. A classical static damage model proposed by Allix and Ladeveze is modified as a fatigue damage model. Subsequently, the model is implemented in commercial finite element software via UMAT subroutine. The results obtained by the finite element simulations verify the experimental findings of Kenane and Benzeggagh for the fatigue crack growth in GFRP composite laminates.

Identification of the effective thermal conductivity of a powdered composite using a genetic algorithm

Abstract This work presents a computational method for the identification of the thermal conductivity of a powdered composite. The thermo-physical properties of powdered composites depend not only upon the intrinsic material properties of the filler and the matrix, but also upon several other parameters including the packing density, the particle shape factor and the particle size. In this paper, a genetic algorithm-based model is proposed for the identification of the effective thermal conductivity of a Bakelite–graphite powdered composite. A comparative analysis is also developed between the genetic algorithm and the experimental, theoretical and finite element results. In comparison with the experimental observations, the genetic algorithm model was found to have error values of approximately 5 %, whereas the errors resulting from the theoretical models were up to 12 %.