Applied Mechanics and Materials Vol. 927

Abstract: Phosphate glasses, characterized by their high thermal expansion coefficients, low melting temperatures, and excellent transparency across a wide spectral range are ideal for optical applications. In particular, phosphate-based glasses are effective hosts for rare earth ions due to their ability to incorporate heavy metal oxides while retaining an amorphous structure. Building on these properties, a series of (50-x)P₂O₅-20ZnO-15SrO-15Li₂O-xSm₂O₃ where x = 0, 0.5, 1.0, 1.5 and 2.0 mol% were prepared by using melt-quenching technique to explore the effects of Sm₂O₃ concentration on structural and optical properties. This study addresses the challenge of optimizing Sm₂O₃ concentration in phosphate glasses to enhance properties such as density, structural stability and emission intensity for efficient green-orange-red luminescence. XRD spectra confirmed the amorphous nature and indicate that samples are glass. The physical measurements indicated that density and molar volume of increased with Sm₂O₃ concentration from 0 to 1.5 mol% and decreased when Sm₂O₃ further increase to 2.0 mol%. FTIR spectra revealed seven spectra bands within range 650 to 1500 nm. The emission spectra were recorded under 402 nm excitation, emits strong emission band at 562, 593, 644 and 705 nm which correspond to excitation from ⁶H_5/2 ground state. The optimal emission intensity was observed at 1.0 mol% Sm₂O₃, highlighting the potential of these glasses for applications in green-orange-red emitting materials.

Abstract: TiO₂ coated plastic optical fiber is developed for ethanol vapour detection. The detection based on intensity modulated evanescent wave fiber optic sensors. The cladding of POF fiber is etched by using acetone and distilled water. TiO₂ solution is prepared by dissolved the TiO₂ pellet powder in isopropanol and stir it by using ultrasonic homogenizer. The optical properties of TiO₂ is characterized by using UV-Vis spectrophotometer. The performance of coated fiber under ethanol vapour concentration range from 1000 ppm to 5000 ppm is examined. The penetration depth, response of the sensor and the sensitivity of coated fiber is observed transiently. The penetration depth of the TiO₂ coated fiber is 32.96 nm to 35.52 nm with sensitivity of 0.001 µW/% and slope linearity of 93.75 %.

Abstract: Dye-sensitized solar cell (DSSC) is a well-known solar cell device because it can convert electrical energy from solar energy. In addition, DSSC has many benefits to offer humankind such as low cost in production, flexibility and eco-friendliness. However, the efficiency provided for DSSC operation is still low compared to the efficiency offered by semiconductor materials. Thus, four different solvents are used to extract natural dye from mangosteen pericarp in order to increase the efficiency in DSSC: pure ethanol, ethanol containing 20 % distilled water, ethanol containing 1 % hydrochloric acid (HCl) and ethanol containing 1 % acetic acid. Other than that, the dyes are examined to observe the optical properties by using Fourier transform infrared spectroscopy (FTIR) and ultraviolet-visible spectroscopy (UV-Vis). FTIR analysis resulted in the functional group presence in the dyes while UV-Vis shows that absorption activity exists in the mangosteen pericarp dyes. In addition, the efficiency of mangosteen pericarp dyes with pure ethanol, ethanol containing 20 % distilled water, ethanol containing 1 % hydrochloric acid (HCl) and ethanol containing 1 % acetic acid are calculated which are 0.080 x 10^-3 %, 0.554 x 10^-3 %, 0.126 x 10^-3 % and 0.102 x 10^-3 % respectively.

Abstract: This paper presents an innovative approach to analyzing metal O-ring sealing performance by integrating fractal theory with fluid mechanics to model interface micro-convex characteristics. Unlike conventional methods, this approach more accurately represents the actual surface morphology of the sealing interface, enabling more precise leakage predictions. The research combines finite element analysis of the sealing surface contact states with hydrodynamic simulations of microchannel leakage behavior. Through experimental validation, the impact of sealing medium, inlet pressure, surface roughness, and compaction load on the contact area and leakage rate is systematically investigated. The key findings reveal that gases exhibit higher leakage propensity than liquids due to their superior fluidity, and the seal leakage rate increases with inlet pressure, reaching 18.86×10^-5 kg/s. Reducing surface roughness enhances interface contact and minimizes micro-leakage gaps, thereby improving sealing performance. Additionally, thresholds for compaction load are identified, beyond which further load increases result in negligible sealing gains. By bridging interface contact mechanics with microchannel leakage dynamics while accounting for realistic surface morphology, this work provides a framework for improving metal sealing ring performance prediction and optimization.

Abstract: Solar desalination is a process to reduce the salt content in seawater by utilizing solar heat. In recent years, the interfacial heating method has been proposed as an alternative to evaporation by creating localized heat on the surface of the liquid. This study investigated charcoal briquettes as a solar absorber material to accelerate the evaporation rate. The experiment was carried out on four basins of single slope type using charcoal briquettes for 8 hours in the sun with variations in the distance between the cover glass and the absorber, namely 3 cm, 4 cm and 5 cm. Charcoal-free basins were also tested for comparison. Temperature is measured at several points in the basin to identify factors affecting evaporation. The results showed that the structure of charcoal briquettes can concentrate the heat required for phase change. The temperature and humidity in each basin also have a similar changing trend where solar radiation strongly influences temperature. Using charcoal can also increase the basin's convection and evaporation heat transfer rates. The maximum desalination efficiency is obtained in basin 2 with a variation of 4 cm cover glass spacing of 31.45%, followed by a variation of 5 cm cover glass distance in basin 3 of 29.92 %, and the variation of 3 cm glass spacing in basin 1 was 26.98%. Whereas in basin 4, with the variation without charcoal, an efficiency of 38.28% was obtained. Desalination efficiency is influenced by several factors: sun intensity, distillate productivity, latent heat of evaporation, and capillary action.

Abstract: Studies on the operation of Wind Power Plants related to the role of the control system are still relatively limited. The role of the control system is very important in the power conversion of power plants. To determine the effect of the power converter control system on the DFIG model wind power plant, modeling of the PLTB with DFIG is needed as well as a control system that can be used for simulations on the network or electric power system. The research thus aims to produce a wind power generation model with a DFIG generator and its control system that can optimally regulate power conversion in operations connected to the electricity grid. Several stages were carried out in this research consisting of literature review, preparation of tools for simulation using MATLAB/Simulink, DFIG modeling with the derivation of applicable equations, model simplification, control design, simulation and analysis. At this research stage, the results obtained are part of the research stages, namely obtaining a simplified DFIG modeling. This simplified DFIG model was obtained after formulating the mathematical equations of the DFIG equivalent circuit, deriving equations for the DFIG transient model and arranging the DFIG model in state space form. Furthermore, by simplifying the shape of the state space, the relationship between the stator and rotor of the DFIG is obtained.

Abstract: This paper presents the development and testing of a smart farming monitoring system utilizing Internet of Things (IoT) and Android technologies to support precision farming practices in Aceh. The system integrates multiple sensors, including DHT11 for temperature and humidity measurement, and soil moisture sensors, all controlled by ESP32 microcontrollers. These components wirelessly transmit real-time data to an Android application, allowing farmers to monitor environmental conditions on their farms remotely. The system was tested at the Universitas Teuku Umar (UTU) farm, where sensor accuracy was validated by comparing the results with external instruments. Linear regression analysis was applied to assess the correlation between sensor data and the external measurements, yielding strong correlations and confirming system reliability. The results demonstrate that the IoT-based monitoring system provides precise and real-time environmental data, offering a valuable tool for decision-making in precision farming. Future directions for the system include expanding its functionalities by integrating additional sensors, improving the Android interface, and exploring predictive analytics through machine learning.

Abstract: The development of agricultural technology in Indonesia is increasingly leaning towards modern, intelligent, and precise farming methods. Unmanned Aerial Vehicles (UAVs) have emerged as powerful tools for identifying, monitoring, and verifying agricultural land, yielding impressive results. UAV-based agricultural land monitoring has shown great potential for providing accurate assessments. This research aims to design and test an agricultural land monitoring system VTOL-UAV that utilizes for sensing and monitoring through unmanned aircraft models. The data collected from shooter camera in the form of topographic images used to analyzed agricultural land. The UAV is equipped with an automatic movement system that operates based on sensing technology. The results present the stability performance for all controlling axes is satisfactory. The recorded responses aligning closely with the desired inputs from both the user and the flight control unit which continuously worked to auto-stabilize the UAV. The vibration levels achieved lower than 50 m/s². This low level of vibration suggests that a camera or similar payload could be integrated in future versions without risking performance or stability.