Cost-effective and high-performance energy storage devices are more crucial in developing societies. The activated carbon from waste biomass is a sustainable and cost-efficient resource for supercapacitor applications. In this work, a comparison between hard shells from macadamia shells and soft shells from durian peel biomass materials for their supercapacitor applications has been demonstrated. Both activated carbon materials show graphitic amorphous structure in XRD and Raman analysis. Also, the three-electrode testing was utilised for the supercapacitor applications. The soft shell electrode shows excellent capacitance, power and efficiency values of 77 F/g, 810 W/kg and 98
Additive manufacturing allows for high design flexibility and material customization in the production of personalized hand orthotics. This study analyses the impact of lattice geometry and material selection on performance and printing quality of 3D-printed hand orthotics fabricated using Fused Deposition Modeling (FDM). Specimens were produced from PLA PRO, ABS, PETG, and a Wood-Fiber composite using rectangular, oval, circular, hexagonal, and oval–hexagonal perforation patterns. Results show that purely hexagonal lattices are not suitable for load-bearing orthoses due to reduced stiffness, whilst rectangular patterns provide higher rigidity but may cause stress concentration. Oval-based geometries offer the best balance between weight reduction, structural integrity, and pressure distribution. PLA PRO and ABS exhibit the highest geometric accuracy and stability, whereas PETG provides beneficial flexibility for wearable applications. Wood-Fiber demonstrates limited mechanical reliability. The findings confirm that oval-based lattice geometries combined with appropriate polymer materials enable lightweight, comfortable, and reliable personalized hand orthotics.
In the digitalization of monitoring of working cycles (MWC) of a power unit (PU) based on the processing of indirect measurement data, the signal of rotational speed fluctuations (RSF) of the crankshaft (CS) was selected as the source of input information. The kinematic uncertainty (KU) of primary converters (PC) of rotation speed was investigated and it was established that the method of discrete measurements of time intervals between two adjacent gear teeth has unsatisfactory metrological characteristics (MC). A method for measuring the transit time of one gear tooth near the sensing element of the PC, which corresponds to one CS revolution, is proposed. It was established that the duration of the obtained time intervals does not depend on the KU. The dynamic uncertainty (DU) of the PC is investigated using the example of modeling the discrete signal of RSF with a limited Fourier series. The measuring transducer (MT) implements a method for measuring the modulation depth of the signal RSF with discrete data recording. A series of measurements with multiple observations of the RSF signal were investigated and its distribution characteristics were obtained. Using an information-based approach, a distribution law for the uncertainty of signal RSF modulation depth measurements is obtained and the suitability of the MT for these measurements is established. The MWC computational procedure uses a cross-correlation function plot between the RSF signal and the cylinder 1 torque.
This study evaluates the performance of a small-scale cross-flow wind turbine (CFWT) mounted on a residential roof in a valley ecosystem. Two-dimensional numerical simulations were employed to examine how the position of the turbine relative to the roof ridge influences its torque and power coefficients across various tip speed ratios. The results suggest that, under daytime anabatic wind conditions, the highest efficiency occurs in a relatively broad range of turbine positions, where power coefficients C_p near 0.3 are obtained. Conversely, nighttime katabatic wind conditions significantly reduce performance, with the maximum C_p falling below 0.2 and the optimal placement narrowed to a rather fixed position. These preliminary findings suggest that a carefully chosen trade-off in turbine positioning is essential to maintain effective energy harvesting throughout the diurnal wind cycle characteristic of valley environments. Additionally, a carefully profiled roof ridge could further improve the performance of the roof-mounted CFWT.
Copacking and reworking activities play a critical role in modern logistics operations, particularly in highly customized supply chains. However, their predominantly manual nature makes them prone to inefficiencies, variability, and limited standardization. This study applies Business Process Model and Notation (BPMN) to model, analyse, and structure the end-to-end copacking workflow within a large European logistics operator, focusing on an external service provider operating within the facility. The methodological approach involved direct observation and segmentation of the process into four phases: Budgeting process, Preparation for the start, Operational handling and Material handling and order closure. The BPMN diagrams developed enabled the identification of bottlenecks, redundant email-based communication loops, manual data reconciliation using Excel and limited system integration across WMS and SAP platforms. Results demonstrate that BPMN effectively increases process transparency, clarifies interdepartmental responsibilities, and supports the identification of opportunities for automation particularly in administrative tasks, quotation validation cycles, and order closure procedures. The study concludes that structured process modelling is a valuable step toward future digitalization and operational optimisation in copacking environments, contributing to greater consistency, traceability, and scalability in logistics services that remain heavily dependent on human intervention.
In the present paper, reverse engineering is applied to the recalculation of a high-speed tubular axial fan without prior knowledge of the rotor and stator geometry. In the first stage, the axial fan was aerodynamically identified by determining the rotor blade profile based on 3D scanning. Graphical processing of the results enabled the reconstruction of the blade’s aerodynamic profile and its identification within the NACA airfoil catalogues. In the second stage, the rotor was recalculated and prototyped, followed by the experimental determination of the machine’s energy characteristics. Experimental results indicated an improvement in fan efficiency of 4
This work examines the temperature boundaries that govern the shift from compressive to tensile residual stress states in precision grinding. A coupled thermo-mechanical model is developed and validated against experimental measurements, confirming that thermally driven plastic deformation constitutes the primary mechanism behind tensile stress formation. The sensitivity of stress outcomes to heat source geometry is shown to be negligible, with discrepancies not exceeding 6
Fused Filament Fabrication (FFF) is widely used technology, yet part mechanical performance and reliability vary because materials, machine hardware, process settings, environment, and operator actions interact. This study develops an Ishikawa diagram to organize these sources of property variability, mapping technician-controlled steps (calibration, orientation, slicing, post-processing, feeding, maintenance) alongside material selection, ambient conditions, and hardware configuration. Unlike existing reviews that often discuss these factors separately, the proposed framework integrates them into a single cause-effect structure. It emphasizes the large number of interdependent slicer settings in modern software and the material-specific effects on strength, dimensional stability, and defect formation. The framework highlights key levers for optimization and standardization and provides a qualitative foundation for future FFF studies.
Polymer gears are increasingly used in mechanical transmissions due to their low mass, reduced noise, corrosion resistance, and cost efficiency, especially in applications involving low to moderate loads. Nevertheless, their viscoelastic behavior, limited thermal resistance, and sensitivity to manufacturing-induced deviations impose specific challenges for design validation and performance assessment. This paper presents a comprehensive study of spur gears manufactured from polymeric materials, focusing on the identification and structuring of a dedicated verification methodology suitable for plastic gears. The research is based on an extensive review of recent literature addressing manufacturing technologies such as injection molding and additive manufacturing (FDM and DLP), material selection, geometric accuracy, wear mechanisms, and functional performance. Key constructive parameters—including module, pressure angle, tooth geometry, and tolerances—are analyzed together with functional parameters such as wear, thermal effects, elastic tooth deflection, and transmission accuracy. Reported experimental results emphasize the strong influence of material choice, process parameters, printing orientation, and shrinkage or thermal effects on gear quality and service life. Based on this analysis, a structured verification methodology is proposed, integrating geometric inspection, optical and 3D scanning techniques, and functional evaluation methods. As a first step toward experimental validation, a compact laboratory test stand for polymer spur gears is currently in early development to support future testing and methodology refinement.
This paper presents a metrological assessment of the influence of selected sheet metal cutting methods on the quality of MAG-welded joints. The study was carried out on specimens made of S235JR structural steel, with edges prepared using five different technologies: guillotine shearing, abrasive waterjet cutting, laser cutting, plasma cutting, and oxy-fuel cutting. Welding was performed without any additional edge preparation while maintaining identical technological parameters, which enabled an unambiguous evaluation of the effect of the cutting process itself on joint quality. Optical 3D scanning was applied for geometric analysis, whereas industrial computed tomography was used for the identification and quantitative evaluation of internal discontinuities. The experimental program was complemented by mechanical testing. The results showed that non-thermal cutting methods are characterized by the smallest geometric distortions and the lowest level of weld porosity, which translates into the most favorable mechanical properties of the joints. In contrast, thermal cutting methods—particularly plasma and oxy-fuel cutting—lead to significant deformations, an extensive heat-affected zone, and an increased number and volume of internal discontinuities, resulting in reduced weld strength and impact toughness. The conducted investigations confirm that the selection of sheet metal cutting technology constitutes an important predictive factor of welded joint quality and should be considered already at the stage of production process planning. In this way, in practical applications where maintaining geometric shapes is important, thermal cutting methods should be avoided.
Supercharging an internal combustion (IC) engine increases intake air pressure, allowing more air–fuel mixture to enter the combustion chamber, thereby improving power and efficiency. Turbocharging achieves this without enlarging the engine, enhancing torque at low speeds and performing under various conditions. A turbocharger consists of a compressor driven by a turbine powered by exhaust gases. The radial rotor geometry of the turbine plays a decisive role in overall efficiency, as an optimized design maximizes energy transfer to the compressor. This study examines the effect of the leading-edge shape of a type A rotor (constant blade inlet angle) on radial turbine performance, while maintaining constant housing dimensions. A fourth-degree Bézier polynomial model was developed to define the three-dimensional blade geometry in two steps: determining the meridional plane and the camber line. Altering the inlet blade angle modifies the leading-edge shape, causing a full 3D transformation near the entry zone. Because turbine flows are three-dimensional, turbulent, and viscous, simulations were performed using ANSYS CFX, which solves the Navier–Stokes equations based on the finite volume method.
The growing instability of global supply chains in 2020–2025 has heightened the importance of transport tariff policy as a structural factor in the cost of logistics and financial performance. Meanwhile, cost elasticity, in the logistics networks, has been transformed due to the swift engineering modernization in the shape of; intelligent transport systems, digital freight networks, and automation. The research focuses on the influence of transport tariff policy on the cost and financial performance of supply chains with engineering innovation as a form of moderation. The study is founded on a balanced panel database on Kazakhstan, Portugal, Estonia, Poland, and Germany with the period 2020 to 2025. Its findings show that the logistics cost associated with an increase of transport tariff index by one point by 3.84 percentage points (p < 0.001). The cost of logistics has a negative relationship on financial performance and its coefficient is −0.62 (p = 0.002). Engineering innovation produces a considerable effect on logistics cost (−4.27, p = 0.001) and has a positive relationship on financial performance (2.47, p = 0.006). The negative correlation between technology modernization and tariff policy (+2.36, p = 0.013) proves the point that the technological modernization cushions the adverse financial effect of tariff increases. Comparative analysis shows that Germany and Estonia with a high level of innovation have lower shares of the cost of logistics and more financial resilience but Kazakhstan is more tariff sensitive.
Computational Fluid Dynamics (CFD) benefits from a solid understanding of physics and numerical methods, which can be challenging for students without a prior background in these disciplines. That makes it particularly difficult to navigate in computing-focused programs. At the University of Minho, a Project-Based Learning approach was applied to teach first-year students of a new Master’s degree in Advanced Computing, in which they were asked to simulate a CFD problem using ANSYS. The proposed project focused on the numerical simulation of an indoor thermal comfort scenario, including airflow, heat transfer, and human thermal comfort assessment. Students were required to document their work in a scientific report that covered the standard stages of a CFD study. This structure aims to familiarize students with both CFD workflows and scientific communication practices. The project outcomes were analysed to assess the effectiveness of the proposed teaching methodology. The results indicate that the Project-Based Learning approach enabled students with no prior background in physics or numerical methods to successfully complete a non-trivial CFD simulation task, demonstrating the potential of this methodology for introducing complex engineering topics in computing-oriented graduate programs.
The accurate selection of climatic databases is a critical factor for obtaining reliable energy production estimates in large-scale photovoltaic systems. This study evaluates the influence of different climatic datasets on energy yield simulations by analysing whether the Typical Meteorological Year (TMY) database currently used in MEGAJOULE’s estimation methodology provides sufficient accuracy when compared to year-specific climatic data. The analysis is based on a utility-scale PV project located in Spain, with a detailed case study focusing on one representative park. Energy production was simulated using PVsyst software with Solargis climatic data, considering both the standard TMY dataset and real-year datasets corresponding to 2021 and 2022. The findings indicate that, depending on the year, either the TMY or the year-specific dataset can provide slightly closer estimates to real production. However, the observed differences are minimal, and no consistent trend was identified that would justify replacing the TMY with year-specific climatic data for energy yield assessments. The results confirm that the use of Solargis TMY data is robust and sufficiently accurate for long-term photovoltaic energy estimation, supporting its continued application in large-scale PV project design and evaluation.
The present study investigates the wear behaviour of grinding wheels during external cylindrical longitudinal grinding of steel workpieces and analyses the effect of longitudinal feed and the volume of material removed on wheel performance. The high-speed grinding was examined using workpieces from steel ХВГ. The wear of the grinding wheel was measured by recording its profile imprints on the workpiece using a specially designed device, which allowed the capture of oscillograms and the determination of step heights along the wheel surface. The results demonstrate that, in longitudinal grinding, wheel wear occurs in steps corresponding to the longitudinal feed per workpiece revolution. The maximum radial wear of the wheel was found to increase with the cumulative volume of material removed, and the number of wear steps was shown to depend directly on the same parameter. Lower feed values per revolution promoted higher local wear in the initial steps, while higher feeds reduced linear wheel wear, contributing to improved dimensional accuracy. Additionally, the grinding ratio was evaluated, showing a decrease with increasing volume of removed material and variation with longitudinal feed. The experimental findings allow the formulation of practical recommendations for selecting optimal grinding parameters.
This case study explores the influence of climate change on the heating and cooling energy demand of a newly constructed residential building located in the vicinity of Bucharest, Romania. The analysis considers key site-related parameters, including climatic classification, local wind conditions, air temperature and solar radiation. The building’s energy performance was evaluated using an analytical calculation approach in accordance with the MC001 methodology applied in Romania for building energy audits. For the reference year 2023, the results indicate an annual cooling energy demand of 2132.83 kWh, while the annual heating energy demand accounts for 5242.05 kWh. To assess the potential impact of future climatic conditions, four climate change projection scenarios were examined, corresponding to the RCP 4.5 and RCP 8.5 pathways for the years 2030 and 2050. The meteorological input data consisted of monthly average outdoor air temperatures and solar radiation incident on both horizontal and vertical surfaces. The results show a reduction in the annual heating energy demand of the building by 1276.05 kWh under the RCP 4.5 scenario, 405.56 kWh under the RCP 8.5 scenario for the 2030-time horizon, as well as a further decrease of 1947.22 kWh under the RCP 8.5 scenario for 2050. In contrast, an increase of 3251.16 kWh in heating energy demand is observed under the RCP 4.5 scenario for the year 2050. Regarding cooling requirements, the findings generally indicate an increase in cooling energy demand across future scenarios, except for the RCP 4.5 scenario for 2050, which exhibits a marginal reduction of 15.47 kWh.
In the early development of tapered roller bearings, the rollers and raceways were typically designed with straight profiles under the assumption that the load would be uniformly distributed along the roller generatrix. However, both theoretical analyses and experimental investigations of line-contact mechanics have demonstrated the presence of significant stress concentrations near the roller ends. This phenomenon, commonly referred to as the edge effect, arises from the interaction between the roller’s straight end profile and the raceway surface. The presence of these edge-induced stress concentrations markedly reduces bearing fatigue life and is a primary cause of premature fatigue failure. The main objective of this paper is to evaluate the impact of the roller profile in a tapered roller bearing subjected to axial and radial loads and intense working conditions. The load distribution and contact deformation of tapered roller bearings for three roller profile geometries (straight, circular crowning, and logarithmic crowning) are investigated using Palmgren’s analytical formulation and a numerical approach based on the influence-coefficient method. The result shows high peaks on pressure distributions at the ends of tapered roller for the straight profile, with a negative impact in the bearing fatigue life.
This study assesses the potential of a herbaceous energy grass, specifically the Napier 4190 cultivar, as a biomass feedstock for thermal conversion under hot compressed water (HCW) to produce biocrude oils. The research work examines the impact of digestion as pretreatment method. The digested grass was subjected to varied HCW conditions at 250–350 ℃. Notably, the findings indicate that the digested grass produces biocrude oil components matching or exceeding those from raw untreated grass, particularly at medium and high temperatures with a 1/5 biomass-to-water ratio. It was found that at 350 ℃, the digested biomass produced about 21
Torrefaction, or mild pyrolysis, is an effective method to reduce moisture and light volatile contents in biomass, thereby improving energy density. Torrefaction pretreatment can also improve the properties of subsequent pyrolysis products. In this work, two-stage pyrolysis of maize cobs was investigated. A screw torrefaction reactor was designed and constructed for torrefying maize cobs at 180, 210, and 240 °C. Torrefied biomass was subsequently subjected to ablative pyrolysis at 450 °C. It was found that the torrefaction temperature enabled a preliminary reduction in the moisture and volatile content of maize cobs. Subsequent ablative pyrolysis of torrefied maize residues was shown to provide higher biochar yield, increasing from 21
Considering the increasing number of people with motor disabilities and the need for their treatment and recovery process, in recent times various devices have appeared that allow medical recovery at different stages. Medical exoskeleton is such a system that facilitate the patients’ mobility and helps them to carry out activities more easily. An exoskeleton for rehabilitation is composed of mechanical elements, sensors and actuators, the latter being the most important. The sensors detect the human intention and transmit the signal to the actuators, which actuate and trigger the movement of the mechanical elements in the exoskeleton component. Depending on the place of the sensor's application on the exoskeleton and the period of use, they are subjected to mechanical wear, losing their ability to function correctly and influencing the durability of the recovery systems. In order to protect and increase the wear resistance of the sensors used in exoskeleton type systems and extend the lifespan of these, an experimental model was created, with force sensors coated with protective materials layers that have superior tribological properties. For these, layers of ethylene-vinyl-acetate (EVA) and polyethylene (PE), with different thicknesses, were tested from a technical-functional point of view. Physical-mechanical and tribological characterization indicate that their coating in the exoskeletons structure effectively protects against wear, only marginally affecting sensors performance and without compromising the data acquisition process. Following the technical-functional analyses, it was concluded that the optimal material for superior protection is the 1.5 mm thick EVA layer.
