Current Issue : January-March Volume : 2026 Issue Number : 1 Articles : 5 Articles
This paper presents the design and analysis of a forklift hydraulic system utilizing an opencenter configuration equipped with unloading (safety-overflow) valves and an emergency lowering mechanism. The hydraulic system includes an external gear pump, double-acting power cylinders, hydraulic distributors, and control valves. A comprehensive approach is undertaken to select system components based on catalog data and to model the flow rate, required torque, and power characteristics of the pump, along with load handling performance as a function of cylinder dimensions and hydraulic pressure. System behavior under various operating conditions is simulated using Automation Studio, enabling performance optimization and fault response assessment. The inclusion of unloading valves and an emergency button enhances system safety by enabling controlled pressure relief and emergency actuation. The impact of thermal effects, filter efficiency, and reservoir design on hydraulic fluid integrity is also addressed. This study aims to improve reliability, efficiency, and safety in hydraulic forklift systems while supporting informed design decisions using simulation-driven methodologies....
Although concentrated solar power (CSP) coupled with calcium looping (CaL) offers a promising avenue for efficient thermal chemical energy storage, calcium-based sorbents suffer from accelerated structural degradation and decreased CO2 capture capacity during multiple cycles. This study used Density Functional Theory (DFT) calculations to investigate the mechanism by which Mg and Ni doping improves the adsorption/desorption performance of CaO. The DFT results indicate that Mg and Ni doping can effectively reduce the formation energy of oxygen vacancies on the CaO surface. Mg–Ni co-doping exhibits a significant synergistic effect, with the formation energy of oxygen vacancies reduced to 5.072 eV. Meanwhile, the O2− diffusion energy barrier in the co-doped system was reduced to 2.692 eV, significantly improving the ion transport efficiency. In terms of CO2 adsorption, Mg and Ni co-doping enhances the interaction between surface O atoms and CO2, increasing the adsorption energy to −1.703 eV and forming a more stable CO3 2− structure. For the desorption process, Mg and Ni co-doping restructured the CaCO3 surface structure, reducing the CO2 desorption energy barrier to 3.922 eV and significantly promoting carbonate decomposition. This work reveals, at the molecular level, how Mg and Ni doping optimizes adsorption–desorption in calcium-based materials, providing theoretical guidance for designing high-performance sorbents....
In this paper, SiC and Si/SiC ceramics were fabricated using direct laser powder bed fusion with chemical vapor infiltration. Their microstructure, mechanical properties and the impacts of silicon addition were analyzed. The incorporation of silicon led to an increase in the relative density of the silicon carbide ceramics from 76.4% to 78.3% and the compression strength increased from 39 ± 13 MPa to 90 ± 8 MPa after laser powder bed fusion with chemical vapor infiltration. The melting and re-solidification of silicon allows the silicon to encapsulate the silicon carbide grains, changing the microstructure and the failure mechanism of the silicon carbide ceramics, resulting in a small amount of silicon residue. In the LPBF-CVI SiC ceramic specimen, the LPBF-formed SiC exhibits a microhardness of 24.2 ± 1.0 GPa. In LPBF-CVI Si/SiC, the spherical dual-phase structure displays a moderately increased hardness (25.9 ± 4.4 GPa), and the CVI-formed SiC exhibits a hardness of 55.3 ± 9.3 GPa....
Towards the creation of a long-lasting and high-performing glulam-product, the optimization of melamine–urea–formaldehyde (MUF) adhesive solutions in order to be in line with worldwide trends of building and cutting-edge material science is a matter of first-priority. However, glulam performance is still highly determined by the efficiency of adhesive bonds, which highlights the necessity of thorough resin and bonding examination. To identify the most effective MUF formulation for structural applications, this study examines the delamination resistance, of spruce three-layer glulam, applying five resins based all on MUF adhesive (EN 14080), differentiating in terms of hardener–resin ratios (1:4 and 1:5) and the applied adhesive amount (1:4 and 1:1) according to ISO 12578. The results revealed that some of the adhesives (A and E) were not suitable for use, the adhesives B and D require further processing, since both achieved a wood failure of 50% in the four applied experiments, while only adhesive C provided almost excellent results in all cases. When the hardener to glue ratio was 1:5 or 1:1, and the application was four times the typical amount of glue, the delamination test requirements were fulfilled, while none of the experiments with a ratio of 1:4 exhibited satisfying adhesion and strength, something that raises concern since this is the ratio recommended by the glulam-production standard. A thorough understanding of MUF adhesive formulations and adhesion mechanisms were approached, which is crucial towards the optimization of wood-based products especially of high-strength requirements as glulam. The hardener-to-glue ratio and the quantity of adhesive were highlighted as crucial factors, underlying the need for accurate formulation and application in structural glulam bonding, while more stringent manufacturing quality control seems to be a necessity....
Rotary lip seals serve as critical sealing components in industrial equipment, traditionally relying on the reverse pumping theory for their sealing mechanism. However, increasing operational demands characterized by high fluid pressure differentials, elevated speeds, and multi-physics coupling environments have revealed limitations in the applicability of the classical theory. This study aims to develop a comprehensive model to quantitatively characterize rotary lip seal performance, specifically frictional torque and reverse pumping rate, and to elucidate underlying mechanisms beyond classical theory. We developed a Mixed Thermo-Hydrodynamic Lubrication (MTHL) model that explicitly integrates fluid–solid–thermal coupling effects to simulate seal behavior under complex operating parameters. The simulations reveal that reverse pumping rate increases near-linearly with rotational speed from −8.54 mm3/s (0 m/s) to 122.82 mm3/s (3 m/s) and 220.27 mm3/s (6 m/s), validating classical theory, while under elevated fluid pressure differentials, a distinct non-monotonic trend emerges: rates evolve from 122.82 mm3/s (0.10 MPa) to 172.93 mm3/s (0.12 MPa), then decline to 52.67 mm3/s (0.18 MPa), and recover to 69.87 mm3/s (0.22 MPa), a phenomenon that cannot be explained by classical sealing mechanisms. Mechanistic analysis indicates that this anomaly stems from a competitive interaction between pressure-driven and shear-driven flow. This discovery not only enhances the reverse pumping theoretical system but also provides a theoretical foundation for optimizing sealing performance under diverse operational conditions....
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