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.
