Background and Objectives: This study’s purpose was to examine the benefit of using a tibial extension in the primary operation of total knee arthroplasty (TKA). This is important because it is not a common practice to use the extension in a primary TKA, a standard configuration offering sufficient stability and good long-term survivorship. The following question arises: which situation requires the use of a standard configuration implant (without a stem) and which situation requires using the extension? Materials and Methods: The opportunity to use the tibial extension in the primary TKA was analyzed in correlation to the tibial bone structural properties. Using finite elements (FEs), the virtual model of the tibial bone was connected to that of the prosthetic implant, with and without a stem, and its behavior was analyzed during static and dynamic stresses, both in the situation in which the bone had normal physical properties, as well as in the case in which the bone had diminished physical properties. Results: The maximum stress and displacement values in the static compression regime show that adding a stem is only beneficial to structurally altered bone. Compression fatigue was reduced to almost half in the case of altered bone when adding a stem. Dynamic compression showed slightly better results with the tibial stem in both healthy and degraded bone. Conclusions: It was concluded that, if the bone is healthy and has good structural properties, it is not necessary to use the tibial extension in the primary operation; and if the bone has diminished physical properties, it is necessary to use the tibial extension at the primary operation, enhancing the stability, fixation, and implant lifespan.

This paper presents a literature review of low-power hybrid wind–photovoltaic (PV) systems and introduces a 3 m diameter prototype rotor featuring twelve PV-coated pivoting blades stiffened by a peripheral rim. Existing solutions—foldable umbrella concepts, Darrieus rotors with PV-integrated blades, and morphing blades—are surveyed, and current gaps in simultaneous wind + PV co-generation on a single moving structure are highlighted. Key performance indicators such as power coefficient (C_p), DC ripple, cell temperature difference (ΔT), and levelised cost of energy (LCOE) are defined, and an integrated assessment methodology is proposed based on blade element momentum (BEM) and computational fluid dynamics (CFD) modelling, dynamic current–voltage (I–V) testing, and failure modes and effects analysis (FMEA) to evaluate system performance and reliability. Preliminary results point to moderate aerodynamic penalties (ΔC_p ≈ 5–8%), PV output during rotation equal to 15–25% of the nominal PV power (P_PV), and an estimated 70–75% reduction in blade–root bending moment when the peripheral ring converts each blade from a cantilever to a simply supported member, resulting in increased blade stiffness. Major challenges include the collective pitch mechanism, dynamic shading, and wear of rotating components (slip rings); however, the suggested technical measures—maximum power point tracking (MPPT), string segmentation, and redundant braking—keep performance within acceptable limits. This study concludes that the concept shows promise for distributed microgeneration, provided extensive experimental validation and IEC 61400-2-compliant standardisation are pursued. This paper has a dual scope: (i) a concise literature review relevant to low-Re flat-blade aerodynamics and ring-stiffened rotor structures and (ii) a multi-fidelity aero-structural study that culminates in a 3 m prototype proposal. We present the first evaluation of a hybrid wind–PV rotor employing untwisted flat-plate blades stiffened by a peripheral ring. Using low-Re BEM for preliminary loading, steady-state RANS-CFD (k-ω SST) for validation, and elastic FEM for sizing, we assemble a coherent load/performance dataset. After upsizing the hub pins (Ø 30 mm), ring (50 × 50 mm), and spokes (Ø 40 mm), von Mises stresses remain < 25% of the 6061-T6 yield limit and tip deflection ≤ 0.5%·R acrosscut-in (3 m s⁻¹), nominal (5 m s⁻¹), and extreme (25 m s⁻¹) cases. CFD confirms a broad efficiency plateau at λ = 2.4–2.8 for β ≈ 10° and near-zero shaft torque at β = 90°, supporting a three-step pitch schedule (20° start-up → 10° nominal → 90° storm). Cross-model deviations for C_p, torque, and pressure/force distributions remain within ± 10%. This study addresses only the rotor; off-the-shelf generator, brake, screw-pitch, and azimuth/tilt drives are intended for later integration. The results provide a low-cost manufacturable architecture and a validated baseline for full-scale testing and future transient CFD/FEM iterations.

In this part of the paper, we will study the behavior of PUR polyurethane at different mechanical and thermal stresses, stresses for which this material behaves very well. It is known that this material behaves well as a protective material against shocks, so it is used as protection against mechanical elements. PUR behaves excellently at uneven static stresses and dynamic stresses. That is why it is used in the construction of the rollers of medium weight mobile devices or rollers that have cam functionality, strongly required for static and dynamic contact. PUR has very good thermal properties, it is used as a thermal insulator when it is in the form of high-density polyurethane foam (PUR / PIR).

We present the first aero-structural evaluation of a 3 m-diameter hybrid wind-PV rotor employing flat-plate blades stiffened by a peripheral ring. Owing to the lack of prior data, we combine low-Reynolds BEM, elastic FEM sizing, and steady-state CFD (k-ω SST) to build a coherent preliminary load and performance dataset. After upsizing the hub pins (Ø 30 mm), ring (50 × 50 mm) and spokes (Ø 40 mm), von Mises stresses stay below 25% of the 6061-T6 yield limit and tip deflection remains within 0.5% R across Cut-in (3 m/s), Nominal (5 m/s) and Extreme (25 m/s) wind cases. CFD confirms a flat efficiency plateau at λ = 2.4–2.8 (β = 10°) and zero braking torque at β = 90°, validating a three-step pitch schedule (20° start-up → 10° nominal → 90° storm). The study addresses only the rotor; off-the-shelf generator, brake, screw-pitch and azimuth/tilt drives will be integrated later. These findings set a solid baseline for full-scale testing and future transient CFD/FEM iterations.

This paper presents the study of the mechanical behavior of polytetrafluoroethylene (PTFE) during tensile tests performed at different strain rates, using standard samples. Test pieces are measured using a non-contact video extensometer. This procedure is particularly precise, as large deformities are involved. The results are compared with a mathematical model to predict the mechanical behavior observed in the experiments. The main objective is to predict the stress-strain curve at different strain rates (6.0 × 10−4, 7.7 × 10−2, 9.2 × 10−2 and 1.3 × 10−1 s−1) using model equations that combine enough mathematical simplicity to allow their use in engineering problems with the ability to describe complex nonlinear mechanical behavior. The material constants (PTFE) that appear in the model equations can be easily identified from tests performed at constant and different strain rates. The virtual studies were carried out using the FEM program under the Solidworks software (Simulation) in which a virtual material was created with the mechanical properties of the analyzed material. The studies contain simulations of tensile, bending and impact tests according to standardized standards.

The method of transporting cement with the help of an air jet through pipes is very practical and reliable. However, improper dimensioning of the constructive and functional parameters can lead to improper functioning, to cement agglomerations in certain areas of the route configuration. In order to be able to know the problem areas and geometries, in this paper a comparative, analytical and virtual study of cement transport through a pipeline route, known as geometry and dimensions, was made. Analytical calculation showed that a floating speed of cement particles of 23.45 m/s, with an air flow rate of 0.155 m ³ /s, is needed to be able to transport a quantity of 40 t/h (11.11 kg/s) of cement. The virtual study done in Flow Simulation showed the behavior of cement particles during transport. The virtual behavior is similar to the real one, with cement particles tending to settle in bends and on long stretches of horizontal pipes. The behavior of the air-cement mixture in the separation cyclone is well exemplified by the virtual simulation. The separation of those two components is well represented and conforms to the real phenomenon.