Engineering Research: Perspectives on Recent Advances Vol. 11

An Analysis of the Thermo-mechanical Autofrettage Process of a Spherical Vessel

Rupali — 2025-10-14

There have been numerous studies on the analysis of residual stresses and deformation for thick-walled cylindrical and spherical vessels subjected to the Autofrettage process and Re-autofrettage process. In this analysis, the results of Elastic-plastic stress distributions in a spherical pressure vessel with thermo-mechanical loads are discussed. Results of the study are obtained with Finite Element (FE) analysis. A quarter of a pressure vessel is considered and modelled with all realistic details. In addition to presenting the stress distribution of the pressure vessel, in this work, the effects of thermo-Mechanical autofrettage on different limit strengths for spherical pressure vessels are investigated. The effect of changing the load and various geometric parameters is investigated. Consequently, it can be observed that there are significant differences between the present thermo-Mechanical autofrettage and earlier (Mechanical autofrettage and Thermal autofrettage) methods of autofrettage for the predictions of Elastic-plastic stress distributions of spherical pressure vessels. Some realistic examples are considered, and results are obtained for the whole vessel by applying thermal load and mechanical load. The actual material curve is used for loading, unloading and residual stress behaviour of spherical pressure vessel. Kinematic hardening material is considered, and the effect of Bauschinger effect factors is studied with thermo-mechanical load. The equivalent Von-Mises yield criteria is used for yield criteria. behaviour of elastic-perfectly plastic is also studied and compared. The influence of Thermo-Mechanical autofrettage over stress distribution and load bearing capacity of spherical vessel is examined. The question of whether Thermo-mechanical autofrettage gives a more favourable residual compressive stress distribution and therefore extension of pressure vessel life is investigated in this analysis. It can be concluded that the autofrettage of the sphere created by Thermo-mechanical loads is more convenient and gives favourable stress distribution than mechanical and thermal loads.

Brazilian Polymeric Packaging Market: Preliminary Analysis, Sustainability and Future Trends

Matheus Delattre Farias — 2025-10-14

Aim: This study conducts an exploratory and preliminary analysis of the polymeric packaging market in Brazil, identifying the main players and highlighting the primary polymers used.

Methodology: A literature review was conducted using generic digital databases and academic platforms (ScienceDirect and SciELO), covering 2010–2025. The Roadmap methodology was used to identify the main packaging technologies. The data analysis was conducted in an integrated manner, using techniques of comparative analysis and critical interpretation. Qualitative and quantitative data were cross-referenced to provide a comprehensive view of the market, considering technical, economic, and environmental aspects.

Results: With a projected market value exceeding US$45 billion by 2029, Brazil's polymeric packaging sector is both robust and complex. Represented by roughly eight major companies, the polymeric packaging segment is a significant creator of formal jobs in Brazil, contributing to the creation of over 150,000 positions. Due to a growing demand for convenience, portability, and innovation, new technologies based on active and biodegradable packaging have been developed. As a result, the technology roadmap made it possible to identify technologies that are already in commercial operation and those that are in the validation phase.

Conclusion: The study revealed that the polymeric packaging industry for food is undergoing a period of intense transformation, driven by national and international regulatory requirements, as well as by growing environmental awareness among consumers. Although innovative technologies, such as active and smart packaging and the use of biodegradable and green polymers, are fundamental for reducing environmental impact, these innovations still face significant challenges. Another critical point identified is the need to develop a more robust logistics infrastructure for selective collection and waste treatment, especially concerning biodegradable packaging and polymers from renewable sources, whose proper degradation depends on specific conditions that are still not widely available in Brazil.

Optimising Depot Storage and Distribution Efficiency through Matching Gasoline Supply to Demand

Eric Obiora Okeke — 2025-10-14

The primary aim of the study is to optimise depot storage capacity and performance by aligning gasoline supply with distribution requirements. This study was conducted for one of the Nigerian National Petroleum Corporation (refiner) depots supplied by a multi-product (gasoline, diesel and kerosene) pipeline. The depot is supplied by a six-inch multi-product (gasoline, diesel and kerosene) pipeline at 82 m³/hour and loading/distribution of 100 m³/hour per arm inside the depot.

The Nigerian National Petroleum Corporation, a refiner, owns and operates a petroleum products pipeline network connected to its 21 storage depots across Nigeria. These storage depots are supplied by a multi-product (gasoline, diesel and kerosene) pipeline network. Since the early 1990s, as gasoline demand increased, the entire supply/distribution chain appeared inadequate. The primary aim of the study is to optimise depot storage capacity and performance by aligning gasoline supply with distribution requirements. This study was conducted for one of the Nigerian National Petroleum Corporation (refiner) depots supplied by a multi-product (gasoline, diesel and kerosene) pipeline. The depot is supplied by a six-inch multi-product (gasoline, diesel and kerosene) pipeline at 82 m³/hour and loading/distribution of 100 m³/hour per arm inside the depot. Distribution/loading facility designed for two arms each for gasoline, kerosene and diesel (or 33.33% for each product), whereas gasoline storage capacity is 55%, diesel, 33%, kerosene 11%, and slops, 1% of the total depot capacity. The design supply to distribution chain capacity ratio showed a mismatch, which in actual operation becomes 2:1. The above design created a ullage problem at sustained supplies, gross under-utilisation of supply chain infrastructures and poor operational performance. After a technical evaluation, a section of the depot storage to loading pipeline network was re-designed and modified to enable product supply capacity to match loading, and minimise storage. Hence, the gasoline loading became 66.67%, kerosene and diesel, each of 16.67%, increasing the actual supply to distribution chain capacity ratio from 2:1 to 2:2 (and when required, can be maximised to 2:3), thereby correcting the apparent mismatch between the supply and distribution chain capacities. Findings showed significant improvement in pipeline transportation scheduling, depot stock and overall product distribution. The modification has enabled the refiner to increase depot and upstream supply chain utilisation.

Effect of Rolling and Post-Rolling Cooling Strategies on Microstructure and Properties of S355 Structural Steel

Efremenko B.V. — 2025-10-14

Structural rolled steels are the primary products of modern ferrous metallurgy. The S355 grade, according to EN 10025, specifies that steel sheets with 16–40 mm thickness should have a yield tensile strength of not less than 345 MPa and an ultimate tensile strength within the 470–630 MPa interval. These sheets are typically produced using low-carbon Mn-Si steel with micro-additions of carbide/nitride-forming elements (Nb, Ti, V, and Al). Enhancing the mechanical properties of rolled steel using energy-saving processing routes without furnace heating for additional heat treatment is advisable. This study compared the effect on the mechanical properties of structural steel for different processing routes, like conventional hot rolling, normalising, thermo-mechanically controlled processing (TMCP), and TMCP with accelerating cooling (AC) to 550^oC or 460^oC. The material studied was a 20 mm-thick sheet of S355N grade (EN 10025) made of low-carbon (V+Nb+Al)-micro-alloyed steel. It was found that using different processing routes could increase the mechanical properties of the steel sheets from S355N to S550QL1 grade without additional heat treatment costs. The optimal temperature for finish rolling during normalising rolling is 840^oC, enabling the enhancement of steel’s mechanical properties to the E420N grade through grain refinement (ASTM grain size numbers 10–11). Further increase in steel strength was achieved by the application of TMCP. The best combination of strength and low-temperature toughness, equivalent to the S550Q grade, is achieved through TMCP followed by AC to 550^oC. This process forms a quasi-polygonal/acicular ferrite structure with minor fractions of dispersed pearlite and martensite-austenite islands, resulting in ductile-brittle transition temperatures of –48.5^oC and –36.5^oC in the longitudinal and transverse directions, respectively. The contributions of various structural factors to the yield strength and ductile-brittle transition temperature were calculated and correlate well with experimental data. The proposed technologies eliminate the need for normalisation with furnace heating. The practical significance of the results has been demonstrated through reducing production costs connected with natural gas consumption.

Environmentally and Economically Efficient Use of Coal Ash in Mortars with Thermal Conductivity Performance for Buildings

Avijit Ghosh — 2025-10-14

A research work was carried out to study the effect of the substitution of sand by coalash in masonry mortar from an energy efficiency point of view. Sand, a natural mineral, is rapidly depleting due to the developmental boom in India, causing a wider demand-supply gap. On the other side, a huge accumulation of legacy ash in Indian thermal power plants is causing serious environmental threats. To address these issues together, two types of conventional mortar grades, marked as MM-3 and MM-5 as per IS 2250, were studied, and the effect of stage-wise replacement by diﬀerent substitution ratios (SR) of sand by coalash (flyash and bottomash separately) on physical parameters as well as thermal parameters were recorded. Fly ash and bottom ash with lime dust and marble dust combinations were also tested as 100% sand-free mortars. Besides satisfying permissible strength criteria as per the Indian Code provision, the thermal conductivity value was found considerably lower than that in the conventional mortar mix. From the experimental results, it was observed that both the MM3 and MM5 grade mortars could be produced at 60% SR by fly ash and bottom ash separately, and corresponding reductions in thermal conductivity values were 69% and 54% respectively, compared to conventional mortar. As regards sand-less mortar for both the grades reduction to the tune of 57% was observed in the corresponding thermal conductivity value. Thus, such ash blended mortar mix appears to be quite beneficial in building envelope application for lowering the overall cooling demand in building, besides utilizing the coal ash to the largest extent and saving natural mineral sand from rapid depletion. The proposed substitution of sand by coalash in building envelope construction application is also economically and environmentally advantageous.

CNN-Based Prediction of Oxygen Supply Needs in under-Actuated HVAC Zones

Yaddarabullah — 2025-10-14

Aims: This study aims to develop a predictive model for oxygen consumption in under-actuated HVAC zones by integrating occupant-centric parameters such as metabolic rate and activity behaviour with environmental and mechanical variables.

Study Design: This is an experimental and computational modelling study utilising a dataset of Variable Air Volume (VAV) damper measurements, fan energy estimation, and occupant metabolic rate calculations.

Place and Duration of Study: The dataset was collected and processed at Universitas Trilogi, Jakarta, Indonesia, during 2024–2025.

Methodology: A curated dataset comprising 11,696 multivariate records was used, including occupant activity counts, environmental parameters (temperature, humidity, air pressure), HVAC operational metrics (airflow, fan speed, brake horsepower, damper percentage), and physiological measures (metabolic rate, daily and minute-based kilocalorie expenditure). Oxygen consumption (L/min) was computed using metabolic energy equivalence. A Convolutional Neural Network (CNN) model was developed and benchmarked against a Multi-Layer Perceptron Artificial Neural Network (MLP-ANN) and a standard Multi-Layer Perceptron (MLP) Regressor. Model performance was assessed using RMSE, MAE, and R² metrics.

Results: Descriptive statistics indicated significant variability in metabolic rate and oxygen demand, ranging from near zero during sedentary activities to peaks above 0.9 L/min during high-intensity activities. The CNN model achieved the best performance (RMSE = 0.0074, MAE = 0.0038, R² = 0.9923), outperforming MLP-ANN (RMSE = 0.0314, MAE = 0.0151, R² = 0.8733) and other benchmarks. Learning curves demonstrated stable convergence without overfitting, while parity plots confirmed strong alignment between predicted and observed oxygen consumption.

Conclusion: The findings confirm that occupant behaviour, particularly metabolic rate, plays a critical role in predicting oxygen demand in under-actuated zones. CNN demonstrated superior predictive accuracy and generalisation by effectively capturing nonlinear and spatio-temporal dependencies. These results suggest that HVAC systems can be optimised through adaptive oxygen control strategies, enhancing both energy efficiency and indoor air quality.

Characteristics of Self-compacting Concrete Incorporating Palm Kernel Shell Ash with Variations in Superplasticiser Content

Siti Aisyah Nurjannah — 2025-10-14

The low water-to-cement ratio in Self-Compacting Concrete (SCC) aims to increase the compressive strength of concrete, but the lower amount of water results in lower workability. Thus, it is necessary to use chemical additives of superplasticiser (SP). SP improves workability while maintaining the specified water-to-cement ratio. This study aims to determine the characteristics of SCC incorporating palm kernel shell ash (PKSA) with varying SP content. The SP content in SCC was 1.5%, 2.0%, and 2.5% of the concrete total mass. The PKSA was 0% and 10% of the total binder mass, and the water to cement ratio was 0.35. The SCC was designed as a C30 class. Some tests of fresh and hardened SCC produced characteristic data that included flowability, viscosity, passing ability, density, and compressive strength. Fresh concrete tests were the slump flow, V-funnel, and L-box tests. There were six SCC mixtures, each with five hardened cylindrical samples for density and compressive strength tests. The addition of SP content increased the flow distribution diameter, decreased viscosity, and increased passing ability. PKSA, as a partial replacement for cement, reduced the density of SCC and increased the compressive strength, but not significantly. The highest compressive strength was obtained in SCC with 10% PKSA and 1.5% SP of 34.75 MPa at the age of 28 days. The use of SP by more than 1.5% increased workability but reduced the compressive strength of SCC by inhibiting the binding process.

Role of Modified Atmospheric Packaging in Fresh Food Preservation and Waste Reduction

G. Amuthaselvi — 2025-10-14

Modified Atmospheric Packaging (MAP) has emerged as an important technology in food preservation and is a vital answer to food waste, which accounts for approximately 30–40% of total global food production. MAP significantly extends the shelf life of fresh foods by inhibiting microbial growth and oxidative deterioration through the alteration of gas compositions in packaging.

MAP uses plastic films with specific gas permeability to manage internal atmospheres. The type of polymer and film thickness are key factors influencing this permeability. Because respiration rates vary between different produce items, films must be selected based on the specific requirements of each fruit (eg, Mango, apple, pears) or vegetable (Broccoli, carrot, cut vegetables) to create an effective modified atmosphere. Using protective gases in polymer film packaging helps extend the shelf life of food products by reducing the growth of common bacteria and microorganisms that affect quality and safety. This article outlines the key benefits of applying such gases and provides examples of specific gases or gas mixtures that can be tailored to various types of food.