The influence of ply stacking sequence on mechanical properties of carbon/epoxy composite laminates

In this work, the effect of ply stacking sequence of carbon/epoxy laminates subjected to flexural, tensile and impact loading was investigated. Five laminates with different stacking configurations were produced using the hand-laying-up technique. This includes a unidirectional laminate, cross-ply laminates, and quasi-isotropic laminates. Following the autoclave curing process, the responses of the composites to bending, tension and impact force were determined according to ASTM standards, and their corresponding strength, stiffness as well as impact energy were evaluated. Likewise, the flexural failure mode associated with each laminate was characterised using an optical microscope. The unidirectional laminates have higher flexural and tensile strength compared to the cross-ply and quasi-isotropic laminates. Moreover, as a result of material symmetry, the flexural and tensile modulus of symmetric cross-ply laminate improved by 59.5% and 3.97% compared to the unsymmetric counterpart. Furthermore, the quasi-isotropic laminates with absorption energy of 116.2 kJ/m2 and 115.12 kJ/m2, respectively have higher impact resistance compared to other samples.Tomas Bata University in Zlin, TBU: CZ.02.1.01/0.0/0.0/17_049/0008407, IGA/FT/2023/004; European Commission, ECInternal grant of TBU in Zlin; project "Innovative and additive manufacturing technologynew technological solutions for 3D printing of metals and composite materials" [IGA/FT/2023/004]; Structural Funds of the European Union project; [CZ.02.1.01/0.0/0.0/17_049/0008407

Review and proposition for model-based multivariable-multiobjective optimisation of extrusion-based bioprinting

Consequent to the development of bioprinting technologies for biomedical applications, especially in tissue engineering, a comprehensive review of extrusion-based bioprinting (EBB) has been written. The review was executed in a manner that laid a foundation for effective optimisation strategies to improve the print resolution or shape fidelity and cell viability of EBB through bioink. However, before achieving this aim the shearing characteristic of the bioink (i.e., shear-thinning or thickening) was described by the Ostwald-de Waele and Herschel-Bulkley models, among other reported models. The dependence of bioink shearing characteristics on temperature and time was also discussed. Emphasis on how these dependencies can be influenced by crosslinking of bioink molecules was further highlighted, which can be covalent (chemical-, photo-cross-linking, etc.) or noncovalent (physical cross-linking, host-guest inclusion, ionic interaction, etc.). Models from literature that can physically describe print resolution and cell viability in EBB were discussed and compared. Therefore, multivariable-multiobjective optimisation strategies were proposed with these models.Univerzita Tomáše Bati ve Zlíně, (CZ.02.2.69/0.0/0.0/19_073/0016941)Tomas Bata University, Zlin, Czech Republic [CZ.02.2.69/0.0/0.0/19_073/0016941

Review on anaerobic digestion models: Model classification & elaboration of process phenomena

Biogas is a well-established renewable energy source produced from anaerobic digestion (AD) of biomass/ feedstock. It is probably the most versatile and efficient biofuel in terms of utilisable feedstocks and energy applications. To monitor, optimise, and control anaerobic digestion (AD), numerous mathematical models describing AD have been developed and reported. Although literature on the use of these models and their reviews have been published, their differences have not been collectively analysed and no generalised classification criteria for these models has been proposed based on such an analysis. This review covers most reported AD models, from the simplest linear equation capturing biogas production rate to complex Anaerobic Digestion Model No. 1. In addition to model classification and biochemical stages in AD, other processes like feedstock hydrolysis or mass and heat transfer essential to AD were discussed, analysed, and available models on them reviewed. This collective and comprehensive review approach has been undertaken to enable the evaluation of the interdependence of all processes, process factors, and process estimations and their individual, and interactive effects on AD.Norges Teknisk-Naturvitenskapelige Universitet, NTNU; Univerzita Tomáše Bati ve Zlíně: IGA/CebiaTech/2020/001, IGA/CebiaTech/2021/002Internal Grant Agency of the Tomas Bata University in Zlin, Czech Republic [IGA/CebiaTech/2020/001, IGA/CebiaTech/2021/002

Robust H∞ controller design for satellite systems with uncertain inertia matrix: A linear matrix inequality approach

This paper discusses the design of a robust H∞ controller for satellite systems that exhibit changes in its inertia matrix within a range of ±5%. Using MATLAB Simulink, the proposed approach is a Linear Matrix Inequality (LMI) by LMILAB Semidefinite programming solver in YALMIP. Simulation results demonstrate the controller’s effectiveness in stabilizing the system against disturbance and maintaining performance despite variations in the inertia matrix

A comparative study of linear and nonlinear optimal control of a three-tank system

In this work, a laboratory scaled industrial interconnected nonlinear Multi-Input|Multi-Output (MIMO) three-tank system, was modelled to control the liquid levels. Ensuing the tradition in the process industry to apply linear controller to most control processes, a linear control scheme was developed for this system. However, since linear schemes are proximate to actual process models, they may not be adequate, especially for highly nonlinear systems. Therefore, a nonlinear control scheme was also developed and compared with the linear scheme. Specifically, optimal linear and nonlinear controllers were designed. In summary, the results of the two control schemes showed adequate performance. However, the linear controller had more robust control and required lesser computational demand compared to the nonlinear scheme. To enhance the computational demand of the nonlinear scheme, a third-party MATLAB toolbox, Automatic Control and Dynamic Optimization (ACADO) toolbox, that interfaces MATLAB with C++ to speed up computations was also utilised, and its results compared, and tentatively validate the earlier solved nonlinear control scheme. © 2022 ISAIGA/CebiaTech/2022/002; Univerzita Tomáše Bati ve Zlín

The Influence of Ply Stacking Sequence on Mechanical Properties of Carbon/Epoxy Composite Laminates

In this work, the effect of ply stacking sequence of carbon/epoxy laminates subjected to flexural, tensile and impact loading was investigated. Five laminates with different stacking configurations were produced using the hand-laying-up technique. This includes a unidirectional laminate, cross-ply laminates, and quasi-isotropic laminates. Following the autoclave curing process, the responses of the composites to bending, tension and impact force were determined according to ASTM standards, and their corresponding strength, stiffness as well as impact energy were evaluated. Likewise, the flexural failure mode associated with each laminate was characterised using an optical microscope. The unidirectional laminates have higher flexural and tensile strength compared to the cross-ply and quasi-isotropic laminates. Moreover, as a result of material symmetry, the flexural and tensile modulus of symmetric cross-ply laminate improved by 59.5% and 3.97% compared to the unsymmetric counterpart. Furthermore, the quasi-isotropic laminates with absorption energy of 116.2 kJ/m2 and 115.12 kJ/m2, respectively have higher impact resistance compared to other samples

Influence of moisture content, temperature, and time on free fatty acid in stored crude palm oil

Consequent to the importance of crude palm oil (CPO) to global food processing industries, and the need for quality assurance of CPO. A kinetic model that describes changes of free fatty acid (FFA) in industrially stored CPO has been developed. CPO FFA is a well-known indicator of the deterioration of CPO. The effect of initial moisture content, storage temperature, and time on CPO FFA have been investigated in this work. Specifically, statistical multi-regression models for changes in FFA and moisture content (MC) were developed at P-value < 0.05 or 95% confidence interval fence. It was found that CPO FFA increases with an increase in moisture content, temperature, and time in their linear term and in respect to decreases in their quadratic term, and interaction between moisture content and temperature. The CPO MC was also found to decrease with an increase in temperature and time and increases in the quadratic term of temperature. Although while the model for CPO FFA, based on Fisher's F-test: F-model(6.80) < F-95%(19.30), showed no lack-of-fit; that of CPO MC showed lack-of-fit, F-model(13.67) not less than F-95%(4.39). Furthermore, based on inference from the statistical model, their kinetic models were also developed. While the CPO FFA kinetic, found to be a half-order kinetic model and its other auxiliary models showed a very good fit (R-2 {0.9933-0.8614} and RMSE {0.0020-3.6716}); that of CPO MC was a poorly fitted first-order kinetic model (R-2 {0.9885-0.3935} and RMSE {0.0605-17.8501})

Renewable energy potential and CO2 performance of main biomasses used in Brazil

This review investigates the effects of the Brazilian agriculture production and forestry sector on carbon dioxide (CO2) emissions. Residual biomasses produced mainly in the agro-industrial and forestry sector as well as fast-growing plants were studied. Possibilities to minimize sourcerelated emissions by sequestering part of carbon in soil and by producing biomass as a substitute for fossil fuel were extensively investigated. The lack of consistency among literature reports on residual biomass makes it difficult to compare CO2 emission reductions between studies and sectors. Data on chemical composition, heating value, proximate and ultimate analysis of the biomasses were collected. Then, the carbon sequestration potential of the biomasses as well as their usability in renewable energy practices were studied. Over 779.6 million tons of agricultural residues were generated in Brazil between 2021 and 2022. This implies a 12.1 million PJ energy potential, while 4.95 million tons of forestry residues was generated in 2019. An estimated carbon content of 276 Tg from these residues could lead to the production of approximately 1014.2 Tg of CO2. Brazilian biomasses, with a particular focus on agro-forest waste, can contribute to the development of sustainable alternative energy sources. Moreover, agro-waste can provide carbon credits for sustainable Brazilian agricultural development.Academy of Finland, AKA: 315019Academy of Finland [315019

Renewable Energy Potential and CO₂ Performance of Main Biomasses Used in Brazil

This review investigates the effects of the Brazilian agriculture production and forestry sector on carbon dioxide (CO2) emissions. Residual biomasses produced mainly in the agro-industrial and forestry sector as well as fast-growing plants were studied. Possibilities to minimize source-related emissions by sequestering part of carbon in soil and by producing biomass as a substitute for fossil fuel were extensively investigated. The lack of consistency among literature reports on residual biomass makes it difficult to compare CO2 emission reductions between studies and sectors. Data on chemical composition, heating value, proximate and ultimate analysis of the biomasses were collected. Then, the carbon sequestration potential of the biomasses as well as their usability in renewable energy practices were studied. Over 779.6 million tons of agricultural residues were generated in Brazil between 2021 and 2022. This implies a 12.1 million PJ energy potential, while 4.95 million tons of forestry residues was generated in 2019. An estimated carbon content of 276 Tg from these residues could lead to the production of approximately 1014.2 Tg of CO2. Brazilian biomasses, with a particular focus on agro-forest waste, can contribute to the development of sustainable alternative energy sources. Moreover, agro-waste can provide carbon credits for sustainable Brazilian agricultural development

Design, techno-economic evaluation, and optimisation of renewable methanol plant model: Finland case study

The current global energy crisis, emphasises the need to simultaneously reduce fossil energy consumption, accelerate renewable energy development, and mitigate global warming, which may arise from situations of dirtier fuel usage. Consequently, this work highlights how captured carbon dioxide from fossil power and manufacturing plants, together with hydrogen purportedly produced via water electrolysis (powered by residual energy from fossil and renewable power plants), can be used to synthesize methanol. Therefore, a methanol plant model was proposed and designed. Multivariable regressions for the plant model were developed and optimised. Furthermore, deduced optimal were used to develop a Langmuir-Hinshelwood-Hougen-Watson (LHHW) kinetic equivalent to the Gibbs reaction model used in the simulation. Also, the plant cost analysis was performed at the optimal, and hydrogen cost was found to constitute the highest manufacturing cost component, hence the costdetermining factor of the plant. Finally, cost-to-size models for various cost components were also deduced.IGA/CebiaTech/2023/004; U.S. Department of Energy, USDOE; Anhui University of Technology, AHUT; Univerzita Tomáše Bati ve ZlíněDepartment of Energy; Internal Grant Agency [IGA/CebiaTech/2023/004]; Tomas Bata Universit