Papers by Imran Mir Chohan
Spectrum of Engineering Sciences, 2025
The construction industry is a major sector that not only delivers essential infrastructure but a... more The construction industry is a major sector that not only delivers essential infrastructure but also ensures safe living environments for communities. This billion-rupee industry is consistently challenged by material shortages, fluctuating costs, logistical disruptions, and labor constraints. In Pakistan, particularly in Karachi, which is the largest urban economic center, there is an urgent need for reliable and efficient supply of materials, manpower, and machinery. This study aims to examine the impact of key supply chain management practices on overall project performance within the construction sector of Karachi. A quantitative research methodology was employed, with data collected from 385 experienced professionals, including project managers, engineers, contractors, and procurement specialists working in prominent construction firms across the city. The data were gathered through structured questionnaires and analyzed using descriptive statistics, correlation analysis, and multiple regression techniques to evaluate the strength and significance of relationships among the identified variables. The results indicate that strategic supplier partnerships exert the most substantial and positive influence on project performance. Additionally, internal lean practices, when effectively integrated with these partnerships, contribute to improved project efficiency and outcomes. The study also identifies several practical challenges that organizations encounter when adopting and implementing lean supply chain practices. This research offers valuable insights for construction professionals, project managers, and decision-makers by emphasizing the importance of developing strong supplier networks, ensuring transparent and timely information sharing, and fostering active client engagement to enhance overall project success.
Nozzles are the important part of propellers generating the thrust and enabling the rockets to mo... more Nozzles are the important part of propellers generating the thrust and enabling the rockets to move in a forward direction. However, their efficient design is imperative to enhance the thrust force and to reduce fuel consumption. Therefore, the aim of this study is to conduct a comparative study of different convergent section angles to evaluate the maximum thrust force of a supersonic nozzle. Computational fluid dynamic (CFD) simulation is performed with different convergent section angles ranging from 42° to 24° by maintaining the same pressure ratio and operating conditions. In addition, the numerical simulation is performed with different working fluids such as air, carbon dioxide, and carbon monoxide. Furthermore, the effect of inlet temperature on Mach number is also analysed. The numerical simulation is performed on an unstructured grid. Meanwhile, the simulation is carried out on a 2D axisymmetric density-based coupled solver with a viscous k-Omega SST turbulence model. The results are validated with previous experimental work and found good agreement with 2.6 percent error. The study revealed that decreasing the convergent angle up to 27° has a favourable effect, and a 1.6 percent increase in thrust force was estimated. Additionally, CO₂ was considered the best working gas with the highest thrust performance, preceded by air, nitrogen, and CO. Furthermore, the inlet temperature has a significant effect on the nozzle Mach number. The findings of this study may be used to design efficient jet engines and rockets.
The Malaysian offshore oil and gas industry depends on vast networks of carbon steel pipes for th... more The Malaysian offshore oil and gas industry depends on vast networks of carbon steel pipes for the production and transportation of crude oil because of their distinct characteristics like good ductility, high strength, and cost-effectiveness. Despite these benefits, these pipelines are vulnerable to damage due to external corrosion induced by hostile marine environments that also affect their mechanical properties, like microhardness. Therefore, this study aims to investigate the corrosion behavior and microhardness of ASTM 106 grade B carbon steel offshore pipelines exposed to different Malaysian seawater locations such as Straight of Malaka (Melaka, Johor, and Negeri Sembilan) and South China Sea (Terengganu, Pahang, and Kelantan). The immersion test was performed for 28 days, resembling different Malaysian seawater environments. Microhardness analysis was conducted through a Vickers microhardness tester. For corrosion characterization, a FESEM study was performed. The findings revealed that higher temperatures and salinity levels in locations like the South China Sea resulted in increased corrosion rates and reduced microhardness compared to regions with cooler temperatures and lower salinity, like the Strait of Malacca. Field Emission Scanning Electron Microscopy (FESEM) analysis showcased significant pitting corrosion in samples exposed to the South China Sea region, corroborating the correlation between environmental factors and corrosion behavior. These findings highlight the crucial impact of regional seawater conditions on the corrosion process and mechanical properties of carbon steel pipelines, emphasizing the importance of understanding these factors for offshore carbon steel pipeline durability.
Influence of Convergent Section Length and Angle on Performance of Supersonic Nozzle
SINDH UNIVERSITY RESEARCH JOURNAL -SCIENCE SERIES
Performance of propulsion system is the key parameter in getting efficient flying vehicles. The e... more Performance of propulsion system is the key parameter in getting efficient flying vehicles. The exhaust nozzle is highly important component of propulsion system, in order to improve nozzle performance understanding of geometrical parameters is mandatory. The nozzle design need optimization for various parameters like inlet, throat and exit width, but impact of inlet convergent angle and length have got less attention. In this research effect of convergent section length and angle of supersonic nozzle were analyzed by keeping same expansion ratio and boundary conditions. The numerical simulation was made on unstructured gird. The computational work is carried out on 2D axi-symmetric density based, coupled solver with viscous k SST turbulence model and linearized through implicit scheme. Study reveals that 28.5o inlet angle would give best result and maximum thrust force would be produced at this angle. From simulation results it was analyzed that flow behavior inside the nozzle is highly complex nature.
Dynamic Structural and Modal Analysis of Tyre Coupling on Unstructured Mesh
Published in AJETR
Sustainability assessment and mechanical characteristics of high strength concrete blended with marble dust powder and wheat straw ash as cementitious materials by using RSM modelling
Sustainable chemistry and pharmacy, Jun 1, 2024
Research into environmentally favorable alternatives to conventional concrete, such as reengineer... more Research into environmentally favorable alternatives to conventional concrete, such as reengineering techniques and the recycling of industrial and agricultural waste, has increased dramatically over the past decade. This research intended to examine the potential benefits of utilizing wheat straw ash (WSA) and marble dust powder (MDP) as supplementary cementitious materials (SCM) in high-strength concrete (HSC). The intention is to decrease carbon dioxide emissions and the amount of Portland cement (PC) required. Concrete formulations containing 0%, 15%, 20%, 30%, and 40% by weight of MDP and WSA as SCM, respectively, were evaluated by using response surface methodology (RSM) modelling for multi-objective optimization. This research assessed the environmental ramifications of employing WSA and MDP as SCM in HSC. Specifically, it examined the impacts on embodied carbon and eco-strength efficiency. Cubical specimens underwent a series of tests to attain the desirable compressive strength of approximately 60 MPa after a period of 28 days. The workability of green concrete decreased as the proportion of WSA and MDP used as SCM increased, according to the study. The optimum compressive strength, flexural strength, splitting tensile strength, and modulus of elasticity of HSC was recorded by 68 MPa, 5.98 MPa, 4.25 MPa, and 40 GPa, at 15% of SCM (composed of 10% WSA and 5% MDP) at 28 days respectively. Using ANOVA, response prediction models were validated and developed with a confidence level of 95%. In summary, the increased application of 20% WSA and 20% MDP as SCM in concrete leads to a 31.64% reduction in the carbon footprint of the material.
Synergistic Effect of recycling waste coconut shell ash, metakaolin, and calcined clay as supplementary cementitious material on hardened properties and embodied carbon of High strength concrete
Case studies in construction materials, Feb 1, 2024
Researchers are investigating eco-friendly binders like coconut shell ash (CSA), metakaolin (MK),... more Researchers are investigating eco-friendly binders like coconut shell ash (CSA), metakaolin (MK), and calcined clay (CC) as supplementary cementitious materials (SCM) in high-strength concrete (HSC). Abundantly available as industrial or agricultural waste, these materials, when combined with Portland cement (PC), offer synergistic benefits. This not only improves concrete performance but also addresses waste disposal issues, presenting a sustainable and environmentally friendly solution for long-term use in HSC production. However, this study performed on fresh and mechanical characteristics of HSC blended with CSA, MK, and CCA alone and together as SCM after 28 days of curing. A total of 504 samples of standard concrete were cast and the cubical samples were tested to achieve the targeted compressive strength about 80 MPa after 28 days. The experimental results indicated that the rise in tensile, flexural and compressive strengths of 9.62%, 8.27%, and 10.71% at 9% of CSA, MK, and CC as SCM after 28 days of curing. As SCM content increases, the density, porosity and water absorption of concrete decrease. Moreover, the workability of fresh concrete is getting reduced when the concentration of SCMs increases in HSC. In addition, the concrete's sustainability assessment revealed that employing 18% MK, CC, and CSA as SCM reduced carbon emissions by approximately 11.78%. It is suggested that using 9% CC, MK and CSA together in HSC yields the best results for practical applications in civil engineering.
A review on life cycle assessment of different pipeline materials
Results in Engineering
Environmentally sustainable development needs techniques and tools to quantify and compare human ... more Environmentally sustainable development needs techniques and tools to quantify and compare human activities environmental impacts for numerous products and services. However, providing products and services to society contributes to a variety of environmental consequences commonly known as environmental impacts. The environmental impact involves the consumption of resources, emissions into the environment, and other interventions like land use, ecotoxicity, etc. To develop environmentally conscious pipeline projects or infrastructure, the environmental impacts of its entire service life must be known. Besides, the life cycle assessment (LCA) is the most advanced tool for assessing the environmental impacts of the entire life of any product or service. The aim of this study is to review the environmental impact of different pipeline networks with different materials on which LCA has been performed. In order to see which phases of the life cycle of pipeline networks and which pipeline materials have higher energy consumption and have major environmental impacts. It has been noticed that the use/operational phase contributes the most to global warming potential (GWP) and has the greatest amount of energy consumption, which is concerning and cannot be overlooked. Now there is a need for some alternative approaches to pipeline networks for a sustainable future.
Frontiers in Materials, 2025
Freshwater supply systems are considered as an important component within urban water systems. Al... more Freshwater supply systems are considered as an important component within urban water systems. Although the development of freshwater supply systems may have significant impact on the environment, there have been only a few studies examining its environmental effects. This paper assesses the environmental impact of four pipeline materials in freshwater supply system using life cycle assessment following ISO 14040–14044 standards. The SimaPro 9.6.0.1 software was used for life cycle analysis. The results indicated that steel has a greater environmental impact in most impact categories during the pipe manufacturing phase than other pipeline materials. During the installation phase, two types of trenches were considered for plastic pipelines and steel pipelines installation and found that the plastic pipe trench experiences its greatest impact during installation phase. To showcase the practicality of the suggested approach, a segment of the Seri Iskandar freshwater supply system was chosen as a case study. The findings revealed that by substituting a portion of the pipes with environmentally sustainable materials, the environmental impact during the manufacturing and materials phase of pipelines used for the construction of FWSS can be reduced by 14% in fossil resource scarcity, 19% in ozone layer depletion, 20% in ionization radiation, 22% in climate change, and 25% in marine ecotoxicity potential.
The coupling is one of the key components of power transmission systems, where it is subjected to... more The coupling is one of the key components of power transmission systems, where it is subjected to highly fluctuating loads, resulting in overstressing, undesired vibration, and shocks. Tire couplings have the capability to absorb sudden jerks and vibrations; therefore, they provide safe and efficient operation. In this research, transient structural and modal analysis of tyre, coupling is carried out by using ANSYS structural code on unstructured mesh. To predict deformation, stresses as well as natural frequencies of structure under time-dependent loads to avoid structure failure and resonance. Unstructured mesh is used to reduce discretization error. Research results reveal that the existing tire coupling design is issafe from a strength and vibration point of view, but it undergoes very large deformation, which becomes a major cause of fatigue failure. It is also concluded that there is enough potential for weight reduction available in the existing design of the coupling, which increases system performance.
Sindh University Research Journal-SURJ (Science Series), 2017
Performance of propulsion system is the key parameter in getting efficient flying vehicles. The e... more Performance of propulsion system is the key parameter in getting efficient flying vehicles. The exhaust nozzle is highly important component of propulsion system, in order to improve nozzle performance understanding of geometrical parameters is mandatory. The nozzle design need optimization for various parameters like inlet, throat and exit width, but impact of inlet convergent angle and length have got less attention. In this research effect of convergent section length and angle of supersonic nozzle were analyzed by keeping same expansion ratio and boundary conditions. The numerical simulation was made on unstructured gird. The computational work is carried out on 2D axi-symmetric density based, coupled solver with viscous k SST turbulence model and linearized through implicit scheme. Study reveals that 28.5o inlet angle would give best result and maximum thrust force would be produced at this angle. From simulation results it was analyzed that flow behavior inside the nozzle is highly complex nature
Scientific Reports, 2024
This research aims to investigate the effects of seawater parameters like salinity, pH, and tempe... more This research aims to investigate the effects of seawater parameters like salinity, pH, and temperature on the external corrosion behaviour and microhardness of offshore oil and gas carbon steel pipes. The immersion tests were performed for 28 days following ASTM G-1 standards, simulating controlled artificial marine environments with varying pH levels, salinities, and temperatures. Besides, Field emission scanning electron microscopy (FESEM) analysis is performed to study the corrosion morphology. Additionally, a Vickers microhardness tester was used for microhardness analysis. The results revealed that an increase in salinity from 33.18 to 61.10 ppt can reduce the corrosion rate by 28%. In contrast, variations in seawater pH have a significant effect on corrosion rate, with a pH decrease from 8.50 to 7 causing a 42.54% increase in corrosion rate. However, the temperature of seawater was found to be the most prominent parameter, resulting in a 76.13% increase in corrosion rate and a 10.99% reduction in the microhardness of offshore pipelines. Moreover, the response surface methodology (RSM) modelling is used to determine the optimal seawater parameters for carbon steel pipes. Furthermore, the desirability factor for these parameters was 0.999, and the experimental validation displays a good agreement with predicted model values, with around 4.65% error for corrosion rate and 1.36% error for microhardness.
Scientific Reports, 2025
Currently, chemical attacks, including acid attacks and sulphate attacks, pose a significant prob... more Currently, chemical attacks, including acid attacks and sulphate attacks, pose a significant problem for the long-term durability of concrete infrastructures that encounter many types of water, including swamp water, marine water, sewage water, drinkable water, and groundwater. Therefore, the intention of this work is to enhance the durability and resistance of concrete against chemical attack by blending titanium dioxide (TiO 2) as nanoparticles into designed cementitious composites. The purpose of current study is to obtain an appropriate TiO 2 based on the cement's weight and polyvinyl alcohol (PVA) fiber in composites using multi-objective optimisation. Thirteen mixtures comprising diverse combinations of variables (TiO 2 : 1-2%, PVA: 1-2%) were formulated utilising RSM modelling. Seven responses were assessed for these mixtures, including weight loss, compressive strength, expansion, a rapid chloride permeability test (RCPT) and a pH test. Analysis of variance, on the other hand, was utilised to construct and assess eight response models (one linear and six quadratics in nature). The R 2 values for models spanning from 88 to 99%. The multi-objective optimisation generated optimal response values and ideal variable values (1% PVA and 1.5% TiO 2). Experimental verification revealed that the predicted values correlated exceedingly well with the experimental data, with an error rate of less than 5%. The outcomes indicate that a 30% rise in compressive strength was noted when 1.5% TiO 2 nanomaterial was incorporated into ECC. Furthermore, the expansion caused by sulphate attack decreases when TiO 2 used as a nanomaterial increases in composites. Besides, when the concentration of TiO 2 in ECC increased, the pH value, and weight loss caused by acid attack reduced. In addition, the RCPT is recorded reducing when the content of TiO 2 increases but it increases with addition of PVA fiber. It has been shown that including 1.5% TiO 2 and 1% PVA fiber yields the optimal results for the building sector.
Frontiers in Materials, 2024
Furthermore, the incorporation of TiO 2 led to reduced drying shrinkage and sorptivity in rubberi... more Furthermore, the incorporation of TiO 2 led to reduced drying shrinkage and sorptivity in rubberized concrete, especially with increased TiO 2 content. The study highlights that TiO 2 inclusion refines pore size and densifies the interface between cement matrix and aggregate in hardened rubberized concrete. This transformative effect results in rubberized concrete demonstrating a commendable compressive strength comparable to normal concrete.
Case Studies in Construction Materials, 2024
Researchers are investigating eco-friendly binders like coconut shell ash (CSA), metakaolin (MK),... more Researchers are investigating eco-friendly binders like coconut shell ash (CSA), metakaolin (MK), and calcined clay (CC) as supplementary cementitious materials (SCM) in high-strength concrete (HSC). Abundantly available as industrial or agricultural waste, these materials, when combined with Portland cement (PC), offer synergistic benefits. This not only improves concrete performance but also addresses waste disposal issues, presenting a sustainable and environmentally friendly solution for long-term use in HSC production. However, this study performed on fresh and mechanical characteristics of HSC blended with CSA, MK, and CCA alone and together as SCM after 28 days of curing. A total of 504 samples of standard concrete were cast and the cubical samples were tested to achieve the targeted compressive strength about 80 MPa after 28 days. The experimental results indicated that the rise in tensile, flexural and compressive strengths of 9.62%, 8.27%, and 10.71% at 9% of CSA, MK, and CC as SCM after 28 days of curing. As SCM content increases, the density, porosity and water absorption of concrete decrease. Moreover, the workability of fresh concrete is getting reduced when the concentration of SCMs increases in HSC. In addition, the concrete's sustainability assessment revealed that employing 18% MK, CC, and CSA as SCM reduced carbon emissions by approximately 11.78%. It is suggested that using 9% CC, MK and CSA together in HSC yields the best results for practical applications in civil engineering.
Results in Engineering, 2023
Environmentally sustainable development needs techniques and tools to quantify and compare human ... more Environmentally sustainable development needs techniques and tools to quantify and compare human activities environmental impacts for numerous products and services. However, providing products and services to society contributes to a variety of environmental consequences commonly known as environmental impacts. The environmental impact involves the consumption of resources, emissions into the environment, and other interventions like land use, ecotoxicity, etc. To develop environmentally conscious pipeline projects or infrastructure, the environmental impacts of its entire service life must be known. Besides, the life cycle assessment (LCA) is the most advanced tool for assessing the environmental impacts of the entire life of any product or service. The aim of this study is to review the environmental impact of different pipeline networks with different materials on which LCA has been performed. In order to see which phases of the life cycle of pipeline networks and which pipeline materials have higher energy consumption and have major environmental impacts. It has been noticed that the use/operational phase contributes the most to global warming potential (GWP) and has the greatest amount of energy consumption, which is concerning and cannot be overlooked. Now there is a need for some alternative approaches to pipeline networks for a sustainable future.
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Papers by Imran Mir Chohan