Institution of Engineering and Technology

Interlayer engineering is widely used to improve charge storage in layered transition metal dichalcogenides, yet most studies rely on nanosized materials where the effects of interlayer expansion and particle downsizing are intertwined. Here, molecular pillaring is translated to bulk molybdenum disulfide (MoS2) using a top-down strategy. Chemical pre-reduction with butyllithium enables exfoliation and restacking in the presence of hexanediammonium (HDA) molecules, forming a pillared MoS2-HDA structure with an expanded interlayer spacing of 0.98 nm while preserving the bulk particle morphology and specific surface area. Electrochemical analysis reveals that improved rate capability primarily originates from the chemical activation associated with the pre-reduction step rather than from interlayer expansion itself. Operando X-ray diffraction and electrochemical dilatometry show that bulk MoS2 undergoes solvent co-intercalation in diglyme electrolyte, leading to pronounced lattice expansion and electrode swelling. In contrast, pillared MoS2-HDA suppresses solvent cointercalation despite its larger interlayer spacing, demonstrating that interlayer expansion alone does not dictate solvent co-intercalation in layered electrodes.

The vibration, damping, and buckling behavior of graphene-reinforced sandwich beams are investigated in this work. The honeycomb sandwich beam is composed of graphene-reinforced with glass fiber-reinforced polymer (GFRP) composite skins and a GFRP strip-reinforced honeycomb core. The governing equations are developed by using the finite element formulation along with the higher-order beam theory (HOBT). A significant degree of agreement is found when comparing numerical results to accessible literature. Additionally, this work examines the effects of graphene reinforcement, GFRP honeycomb core thickness, graphene-reinforced GFRP skin layer thickness, and end conditions on the vibration, damping, and buckling behavior of honeycomb sandwich beams. The sandwich beam with graphene-reinforced skins outperforms the neat sandwich beam in terms of natural frequency, damping, and buckling, with improvements of 8.04%, 10.56%, and 18.29%, respectively. The lightweight GFRP honeycomb core, combined with the advanced graphene-reinforced composite face sheets, offers interesting applications and further research.

The integration of hybrid renewable energy systems, particularly solar and wind, into power grids presents unique challenges and opportunities. This paper examines the operational dynamics, technical constraints, and optimization strategies for integrating hybrid energy systems into the grid under varying environmental, load, and grid strength conditions. By analyzing performance data and employing conventional control strategies, this study highlights methods to enhance grid stability, efficiency, and reliability. The findings contribute to the growing need for sustainable energy solutions in the face of increasing global energy demand and climate change.

In this study, 3D printed breakboards based on the elytral suture of Phloeodes diabolicus were tested along with 3 other traditional joints with alterations in suture dimensions and variation in order to compare strength to weight efficiency, additionally accounting for displacement when under load. These models were then tested to measure both strength and displacement over time in order to quantify load tolerances. Our hypothesis suggests that the 2-layer thick ironclad suture-based board would have the most efficient load-bearing capacity compared to other sutures presented in this experiment. Ironclad beetles, also known as the diabolical ironclad beetle, are renowned for their impressive load-bearing capacities and have been studied extensively by researchers for use in real-world biomimetic applications such as construction in the forms of buildings or bridges where strong load-bearing joints are critical. The utilization of such biomimicry in infrastructures can significantly increase load and stress tolerances while simultaneously minimizing excess material, creating more efficient, cheaper, and safer infrastructures for use. Our findings for the 1st testing phase did not fully align with our hypothesis, as the ironclad-modeled sutures were not the strongest joint in terms of strength-to-weight efficiency when compared to the other joint types. However, the 2-layer thick boards were measured to be exponentially stronger compared to boards with only 1 layer. Overall, the ironclad-based sutures were strong, but it underperformed compared to the other joints presented in the experiment. Due to the fact that the ironclad-based sutures in the 1st phase of testing might have not been reflective of the natural counterpart, a second phase of testing aimed at testing variations of more accurately constructed ironclad-based sutures is being implemented. However, this study facilitates the fundamental understanding of the detailed mechanics of ironclad beetles.

Abstract High-temperature superconducting coils are used in various large-scale applications, like rotating machines and high-field magnets. However, modeling these coils is a complicated and time-consuming process, especially due to the non-linearity of the current–voltage characteristics of the superconductors and the complex multiphysics involved. In this work, we used a fast homogenized method to model the coupled electromagnetic and electrothermal properties of racetrack and pancake coils for different applications. For this purpose, various formulations wielding homogenization methods are used and benchmarked with each other, as well as with models considering the detailed structure of the HTS tapes. We observe a very good agreement between different models (homogenized and detailed), and we discuss the pros and cons of the inclusion of insulating layers between the turns in homogenization. This work was performed under the collaboration of the COST action modeling teams and can be used as a review of the state-of-the-art superconductor modeling techniques, and a source for the development and benchmark of future numerical methods.

Abstract Polymer-based composites have been drawing the attention of the research community for many decades, not only in academia but also in industry. However, continuously increasing environmental concerns have led the researchers to focus on natural composite materials. This is a challenge for researchers to develop a natural composite without compromising the composites’ excellent mechanical properties and tribological performance. In this research, coir and sugarcane are selected as the natural fillers, and epoxy resin has been chosen for matrix material. To look into the crystallinity of composites, XRD analysis was done. In addition, a mechanical study was done to look at the manufactured composites’ tensile and flexural characteristics. The tribological performance (i.e., wear rate and friction coefficient) of the composite samples is investigated by using a pin-on-disc setup. The parameters such as filler loading and normal load affecting the tribological performance of epoxy-based natural composites are studied. The results show that the wear and friction characteristics of the composite reinforced with sugarcane and coir were 10.78% and 57.80% lower than those of the neat composite, respectively.

La finalidad del artículo es la de evaluar el proceso de crecimiento histórico de la capacidad receptiva hotelera; medir la producción y la renta generada por el sector; presentar los aspectos básicos del empleo en la actividad; definir las características de la demanda hotelera; estimar el valor del capital y los problemas financieros existentes.

This paper deals with a two-stage hybrid configuration of a solar photovoltaic array (SPVA) and battery energy storage (BES) distributed generation source (DGs) connected to the three-phase utility grid and critical non-linear load via a DC-AC voltage source converter (VSC). To improve the effectiveness of this system, the perturb and observe (P&O) technique is employed to extract the maximum power from the SPVA. A DC-DC boost converter is used to boost up the generated SPVA voltage for MPPT. BES is directly connected before VSC to support the critical load during the outage of the grid and SPVA. Unbalanced load, unbalanced grid voltage (voltage sag and swell), DC offset, and environmental effect, i.e., change in solar insolation are considered when evaluating the system's effectiveness. To obtain reference grid currents extended state lowpass second order generalized integrator (ESLSOGI) is employed for voltage source converter control, which converges quickly and exhibits fewer steady-state fluctuations. With this control, grid current harmonics adhere to IEEE-519 standards, performance is acceptable under a variety of load and environmental conditions, and smooth operation changeover is done between grid-connected mode (GCM) and standalone mode (SAM).

Fossil fuels cause greenhouse gas emissions and are perceived to deplete, hence the use of renewable energy is considered crucial. These renewables include the use of solar thermal energy in concentrated solar power (CSP) generation and solar drying applications. However, solar energy is intermittent, thus solved by incorporating thermal energy storage (TES) to store heat energy for future use. However, the most common weaknesses in TES materials are high cost of investment, environmentally unfriendly and are not locally available. Using natural rocks is recommended as they are readily available, affordable and efficient TES materials for solar drying applications at 40-75 °C and concentrated solar power generation at 500-600°C. Despite its generational use in thermal applications, soapstone rock has not been studied as a TES material. Moreover, site specificity has not been investigated in spite of being stated to affect the potential of rocks in TES. Therefore, this study investigates the potential of soapstone rock as a TES material, and the influence of the geological-tectonic settings. In the present study, experimental characterization of selected natural rocks namely soapstone and granite, was done to investigate their thermal properties at 20-950°C. Conclusively, soapstone rock from the Craton geo-tectonic setting had the best properties and it had the highest young’s modulus, thermal capacity, thermal conductivity and had a weight loss of only 0.75 % at 900°C. At high temperatures, it did not show visible fracture. Moreover, soapstone and granite from the Craton and Usagaran geo-tectonic settings exhibit significant differences

We construct a two-factor pricing model for contingent convertible bonds having a conversion to equity loss-absorption mechanism, triggered by the event of the issuer’s Tier 1 ratio falling below a predetermined level. The two stochastic factors are the issuer’s equity price and Tier 1 ratio. A key feature of the model is its calibration to market using an option-adjusted spread parameter. Using a Taylor approximation, we assess the model’s explanatory power to decompose returns and attribute them to various risk factors, most notably those directly related to the issuer’s equity.