Industrial pipe insulation is almost always selected from discrete catalog steps of material, thickness, and jacket/cladding, yet a large share of the literature optimizes a continuous thickness. This paper develops a directly implementable, catalog-based method that outputs the globally optimal insulation choice for each operating temperature and summarizes it as temperature bands with explicit transition points. The approach combines a physically transparent heat-loss model with a simple, robust optimization over the finite decision set.
In social housing are commonly used panels made with wood particles like partitioning walls, because of its low cost and ease of assembly, dry way. One problem with these panels is their low acoustic insulation. In the Experimental Economical Housing Center of Cordoba, Argentina, a research team has developed panels for housing made from recycled plastics and polyester resin, more ecological than the traditional ones made with wood particles, and with technical advantages. They are manufactured with recycled various plastics from food, perfumery or cleaning packaging, waste production from factories due to failures in sheet thickness or ink application. These panels contribute to the environmental decontamination, because they are made from plastic residues. Most of this waste is buried, accumulated or burned in municipal garbage dumps without any use, causing environmental degradation. The technical advantages of these panels are that they have higher acoustic insulation than conventional panels made with wood chips or fibers. They are also water resistant, and they have higher flexural resistance. This paper presents the study about the acoustic insulation property of this panel, comparatively with other conventional panels made with wood particles. Besides, different designs of multilayer panels for housing enclosures are presented, with steel frame structure, and the corresponding Sound Reduction Index of each alternative was calculated. The results were compared with the regulations in force in our country (IRAM Standard 4044 - 2014) regarding acoustic requirements, to verify its compliance.
Young’s modulus and internal friction of bulk GaN single crystal samples were measured as a function of temperature in 100 K to 700 K range. The internal friction strongly depends on sample dimensions and measurement frequency (3 – 10 kHz). The experimental values are compared to the theoretical model for thermoelastic damping. The model and the experimental data match very well in the whole temperature range and for different frequencies indicating that the thermoelastic damping is the main energy dissipation mechanism.
This study presents the comprehensive design and fabrication of a bespoke laboratory-scale Rotary Friction Welding (RFW) machine, developed by repurposing a J23 mechanical press frame to provide a cost-effective research platform. The system integrates a 7.5 kW motor with VFD control for precise rotational speeds up to 1500 RPM and a two-stage hydraulic circuit to manage friction and forging pressures. To validate the machine's efficacy, twenty experimental runs were conducted on similar-material joints, specifically AISI 304 stainless steel, AA1050 aluminum, and AISI 1030 structural steel. Mechanical testing and microstructural analysis demonstrated that the system consistently produces high-integrity bonds, with AISI 1030 steel joints achieving 100% joint efficiency and AISI 304 samples reaching ultimate tensile strengths exceeding 800 MPa. The results confirm that the reoriented horizontal frame maintains the necessary axial alignment for high-quality solid-state joining, making it a reliable and accessible tool for academic investigation into RFW process optimization.
Environmental regulations, fluctuating energy prices, and uncertainties in the international energy markets motivate consumers to ensure their security of energy supply. One method to achieve this goal is to use heat storage equipment, which is scalable and applicable in both industrial and residential environments. The present study focuses on latent heat energy storage utilizing paraffin as a phase-changing material. A cube-shaped heat storage test device was investigated both experimentally and numerically. We used the obtained experimental data to validate our effective numerical modeling approach based on the enthalpy method. We proposed an effective numerical approach to take into account the material nonlinearities and the effect of convective flow phenomena on heat transfer processes, while neglecting the exact flow field and spatial distributions.
In open-surface evaporation systems, the simultaneous transfer of heat and mass is vital for establishing the interrelated exchange of energy and mass between liquid and gas phases. This research offers a comprehensive examination of the physical mechanisms that control evaporation in both natural and forced convection scenarios. It also assesses different theoretical and empirical approaches for calculating the heat transfer coefficient. It has been shown through experiments and numerical analyses conducted in the past that the precision of predictions regarding heat and mass transfer is greatly influenced by factors such as geometrical configurations, convection regimes, and measurement accuracy. Various analytical methods are examined, such as the heat balance equation method that connects heat flux to temperature difference and evaporation rate through interfacial energy balance, and the dimensional analysis method that formulates general correlations based on important dimensionless numbers like Nusselt, Prandtl, Reynolds, and Rayleigh. Moreover, the heat–mass transfer analogy offers a practical framework for estimating one coefficient based on the other by taking advantage of the similarity between temperature and concentration fields. Furthermore, the Ackermann correction factor is implemented to consider the effect of vapor flow on the heat transfer, thereby improving estimations of the heat transfer coefficient during evaporation and diffusion. This research creates an extensive framework for the analysis of open-surface evaporation and the enhancement of heat and mass transfer coefficient predictions. This is achieved through a combination of theoretical, experimental, and analogy-based methods, leading to improvements in the design and functioning of thermal and evaporative systems.
This paper presents the simulation study of passivated backgated graphene field-effect transistors (GFETs) with different channel lengths using Victory Device tool by Silvaco TCAD. The passivated backgated GFETs were designed for radiation device applications. Six GFETs models with channel lengths ranging from 0.1 µm to 10 µm were analyzed to investigate the influence of variation in channel length on the conductivity of GFET. Nearly all devices with shorter channel lengths exhibit ambipolar characteristics with V-shaped curves, indicating the conductivity of holes and electrons at different bias conditions. Interestingly, GFETs with longer channels, specifically 3 µm, 5 µm, and 10 µm, exhibited unexpected W-shaped transfer characteristic curves, featuring multiple charge neutrality points (CNPs). This behavior is attributed to the non-uniform doping induced by charge interactions between the channel and the passivation layer. The central region of the channel may experience a higher doping effect due to impurity diffusion from the passivation material compared to the region near to the metal electrodes. However, the W-shaped curves of longer channel GFETs become less prominent when compared to smaller channel length devices. This suggests that high conductivity in shorter channel GFETs dominates the overall transfer curve performance. The analysis of output characteristics (I D –V D ) at V G = 10 V further supports the influence of channel length on device performance, with the shortest channel length (0.1 µm) recording the highest saturation current (I SAT ), followed closely by 0.6 µm, aligning with its strong ambipolar transfer characteristics. These findings highlight the importance of channel scaling in designing stable and reliable backgated GFETs for radiation applications.
In the global transition towards renewable energy, a leading role is played by photovoltaic (PV) technologies. However, the increasing growth of installed PV panels, together with the rise of the number of modules reaching their end-of-life phase, make the sustainable management of electronic waste a crucial aspect. The reduction of energy consumption and polluting emissions and the maximization of material recovery represent the ultimate purpose of demanufacturing processes. Here, cryogenic delamination is proposed as an innovative strategy, as it exploits the thermal and mechanical properties of PV module constituents to achieve the cleanest possible separation of layers, allowing for the recovery of strategic materials (silicon, aluminium, silver, copper). This work aims to combine experimental and numerical approaches in order to obtain a comprehensive understanding of the fundamental mechanisms governing the process: the overall objective is represented by the process optimization to enable the exploration of various operating conditions without the need for costly and time-intensive experimental campaigns and, ultimately, the implementation of such technology at the industrial scale.
Silicon carbide (SiC) complementary metal-oxide-semiconductor (CMOS) technology and its circuit applications have been rapidly advancing, making the stability and reliability of planar p-channel metal-oxide-semiconductor field-effect transistors (PMOSFETs) increasingly important. In this study, a channel-length-dependent threshold voltage instability was observed under both gate bias stress and gamma-ray irradiation. The results indicate that the majority of positive charge trapping originates from hole injection induced by external bias. Secondary ion mass spectrometry (SIMS) analysis confirmed the retention of aluminum species in the gate dielectric after thermal oxidation. Based on these experimental findings, a dopant diffusion model was proposed, suggesting that dopant contamination in the gate oxide is the primary cause of the channel-length-dependent instability.
Titanium alloys combine strength, low weight, and corrosion resistance, making them vital in high-performance industries; yet machining generates substantial chips that is difficult to recycle via conventional remelting due to contamination and high energy requirements, reducing material sustainability. Solid-state recycling methods, like Shear Assisted Processing and Extrusion (ShAPE), provide a promising alternative by consolidating chips below the melting point while preserving alloy chemistry. This study assesses the environmental performance of ShAPE across a system boundary spanning degreasing through consolidation and extrusion. Impacts were quantified using Cumulative Energy Demand (CED), Global Warming Potential, Environmental Footprint, Average Dissipation Rate (ADR), and Lost Potential Value (LPV), with ADR and LPV applied for the first time to solid-state recycling of scrap from discrete manufacturing. Scenario analyses addressed variations in torque, argon consumption, and electricity mix. Energy demand and CO 2 -eq for the ShAPE process were estimated at 279.51-567.75 MJ and 17.22-32.35 kg per kg of wire, respectively, with sensitivity analysis showing that variations in torque constitute the dominant determinant of these environmental outcomes. While energy demand is comparable to, or moderately lower than, that of traditional wire fabrication only under low-and baseline-torque conditions, ShAPE substantially reduces the resource dissipation and lost material values, with its overall environmental impacts further decreasing by 45.45% when powered with greener electricity. These results highlight ShAPE as a viable route for circular titanium production, preserving material value & reducing dependence on primary extraction.
Adsorbent beads composed of Chitosan (CS), MIL-101 (Fe), and Polyethyleneimine (PEI) were synthesized for Methyl Orange (MO) adsorption. Parametric studies testing the effects of pH and number of adsorption and desorption cycles on percent MO removal showed the beads’ good performance across a wide range of conditions. A percent MO removal of at least 93% was maintained from pH 2 to pH 9 with a maximum percent removal of 98.6% obtained at pH 3. In addition, the beads remained functional for at least 5 cycles of adsorption and desorption with a percent MO removal of 98% across the cycles. Kinetic modeling was performed and a pseudo-second order kinetic model with an R 2 of 0.981 was obtained implying chemisorption as the rate limiting step. Adsorption equilibrium data for MO were best fitted into the Sips isotherm model which suggests that adsorption occurs on a heterogeneous surface. From the Sips isotherm model, the maximum adsorption capacity was determined to be 1253.44 mg/g, highlighting the viability of CS – MIL-101 (Fe) – PEI beads as an adsorbent for wastewater treatment.
The reshaping approach is widely considered a virtuous strategy in line with the pillars of the Circular Economy. According to this approach, End-of-Life (EoL) components are subjected to a second forming process to achieve a new functional geometry. However, EoL parts often exhibit a non-uniform thickness distribution and work-hardened zones resulting from the primary manufacturing step, which makes the design of the reshaping step not trivial. Beyond the standard objectives like avoiding fracture and minimizing springback during the reshaping operations, one of the most concerning aspects is the complete removal of the geometrical features coming from the initial forming process. Flexibility and versatility of the forming process are unavoidable requirements to make the reshaping successful. Therefore, three different reshaping routes are numerically investigated in the present work: (i) reshaping by hydroforming (RH) at room temperature; (ii) reshaping by gas forming (RGF) at hot temperature; (iii) a hybrid approach, based on the combination of an intermediate deformation step via Single Point Incremental Forming followed by sheet hydroforming (RHA). The three routes share the same EoL, characterized by the presence of a deep-drawn square feature. Comparing the three routes, in terms of final shape and thinning distribution, with a reference case study (represented by the sole hydroforming process carried out on an undeformed flat blank) allowed to conclude that the feature removal and a non-severe thinning could not be achieved simultaneously: in fact, while RGF and RHA ensure a more evident suppression of the pre-existing feature, they simultaneously induce a more pronounced and localized thinning compared to the RH route.
Steel is the most used material for concrete reinforcement; however, it performs poorly in aggressive environments (e.g. coastal areas) owing to corrosion (moisture and chlorides). This study aims to analyse the tensile strength of steel and glass fibre-reinforced polymer (GFRP) bars through laboratory testing to assess their feasibility and application in construction. Steel bars were tested by ASTM E8/E8M–22, obtaining values of 606.61 MPa (Ecuador) and 676.46 MPa (Peru), whereas GFRP bars were tested following ASTM D7205/D7205M–21 (1,000 MPa). The analysis indicated that GFRP bars offer structural advantages (suitable for elements in coastal zones with low to moderate seismic activity), environmental benefits (lower CO₂ emissions during production), and enhanced durability (corrosion resistance).
With ever-increasing power conversion densities in electric power converters, the volume of the converter must shrink for a certain power rating, which in turn demands the reduction in size of the energy-storing passive component. Constant power rating of those systems and the reduction of size of passive components leads to a higher switching frequency of the semiconductor power switches. At high switching frequencies, dynamic losses in the power semiconductor device dominate the overall power losses. Consequently, novel device concepts that address dynamic power losses may be superior to conventional power devices, even though they might have a higher static on-state loss. In this paper, the concept of the power tunneling field-effect transistor (Power-TFET) employing tunneling between a highly p-type doped source region and a n-type accumulation channel is proposed and compared to an equivalent LDMOS in terms of static and dynamic losses. Devices fabricated in a 2 µm 4H-SiC technology are measured and compared to evaluate the viability of the Power-TFET device concept. The fabricated Power-TFET shows high-voltage blocking capability and has a switchable tunneling junction with on-and off-state, despite showing high on-state resistance due to the tunneling through the wide bandgap of 4H-SiC. The alternative of tunneling through a switchable Schottky barrier is simulatively explored to solve the high on-state resistance of the pn-junction based Power-TFET.
This study investigates the comparative flexural performance of concrete reinforced with three distinct types of natural fibers: abaca, banana, and ramie. Concrete specimens were prepared with varying fiber contents (0%, 0.25%, 0.50%, 0.75%, and 1.00%) for each fiber type, and their slump and flexural strength were evaluated. The slump test results revealed a consistent reduction in the workability of concrete as the fiber content increased, indicating the need for optimizing the fiber content to balance the enhanced mechanical properties with the workability requirements. The flexural strength test results showed that the incorporation of abaca and banana fibers at an optimal content of 0.5% significantly improved the flexural strength of the concrete, with increases of 59% and 50%, respectively, compared to the control mix without fibers. The ramie fiber-reinforced concrete exhibited a relatively lower enhancement in flexural strength compared to the abaca and banana fiber-reinforced mixes, though its performance remained comparable to the control. Further analysis using ANOVA confirmed the statistical significance of the fiber content on the flexural strength for abaca and banana fibers, underscoring their efficacy in enhancing the concrete's load-bearing capacity.
This paper presents the fabrication and characterization of a cell-to-cell integrated SiC lateral bi-directional MOSFET (L-BiD-MOSFET), with blocking performance analyzed through correlation of experimental results and 3D TCAD simulations. The fabricated devices exhibit a breakdown voltage of 600 V, notably lower than the 900 V predicted by 2D simulations. To address this discrepancy, 3D TCAD simulations were performed, which identified electric field crowding at the finger edges as the dominant factor limiting the breakdown voltage. To mitigate this effect, an extended P-top edge design was introduced, which increases the simulated breakdown voltage by more than 10%. Experimental results on devices incorporating the proposed design confirm improved breakdown capability, demonstrating good agreement with simulations. These results highlight the importance of accurate 3D simulation for edge effects in lateral structures. Overall, the proposed design strategy provides valuable guidance for the development of high-performance lateral bi-directional SiC power devices.
Metal-forming is a manufacturing process that involves non-linear elastoplastic deformations to shape a blank into a complex geometry. These processes are governed by numerous parameters, with significant influence on the final product. To analyse the effects of such parameters, large-scale finite element (FE) simulations are often conducted. However, these models are computationally expensive and often unsuitable for real-time analysis. To overcome these limitations, surrogate models have emerged as powerful alternatives. In this study, we propose a physics-informed recurrent neural network framework (PIRNN) to evaluate displacements and strain tensor components. In particular, the latter are not a network output but are obtained through the application of kinematic relations. Given the initial configuration as input and the final configuration as output, it is possible to evaluate the deformation gradient. The impenetrability condition is then injected into the loss to improve the estimation of displacements and strain tensors. The PIRNN model, referred to as a kinematics-informed recurrent neural network, is trained on data generated from FE simulations of a deep-drawing process. The accuracy of the model is evaluated on a test dataset (design points that the model does not see during training) using different error measures. The results show that the proposed KI-RNN model can fairly reproduce the FE simulation results fairly well.
