The current-voltage (I-V) characteristic plays a vital role in operating photovoltaic (PV) systems as it permits predicting the performance of systems and comparing the quality between different kinds of PV panels. In this paper, the analytical methods describing the I-V curves by analyzing PV model are discussed. After that, a new approach is proposed to improve the drawbacks of reviewed methods. All methods, both reviewed and proposed, extract the IV characteristic of a PV panel using only data in the data sheet provided by its manufacturer. An investigation is conducted on a multi-crystalline PV panel to verify the effectiveness between methods. The results prove the accuracy of these methods since the RMSE ranges from 0.039 A to 0.239 A. The improved method shows its reliability since the RMSE does not vary a lot when the operating conditions change. To effectively evaluate five parameters of the PV model at other temperature irradiance conditions, the proposed model and Villalva’model are applied to predict the I-V curves of PV panels with the same algorithm as the ones at the standard test condition. This suggestion proves its effectiveness when reducing a lot the RMSEs of corresponding methods.

View full abstract

Dielectric elastomer actuators (DEAs) are a type of versatile transducers that are lightweight and energy efficient. They hold great promise for soft actuators such as those resembling muscles. DEAs consists of a thin elastomer sheet sandwiched between two compliant electrodes. In the actuation mode, applying a voltage on the electrodes triggers the attractive Coulombic force between opposing charges. The Coulombic force compresses the elastomer, which causes it to expand perpendicular to the applied electric field. In this paper, various polymer mixtures and a curing agent of polydimethylsiloxane (PDMS), are used to optimize the actuation performance of DEAs. To understand the mechanical properties of the material, a series of single pull tensile tests is conducted. Stress softening in tensile tests of PDMS depends on the mixing ratio of the base polymer and the curing agent. Increasing the polymer ratio in PDMS yields a softer material. We expect that softer materials have a better performance for DEAs since they require a lower voltage for the actuation. Furthermore, we also compute the nonlinear mechanical Mooney-Rivlin, second-order Ogden, and Neo-Hookean models from the stress-strain data. Although all models agree fairly well in the lower-strain region, the second-order Ogden model is preferable in the strain-hardening region.

View full abstract

Catalytic combustion on platinum surface is one of the energy sources for portable power generator applications. The combustion mechanisms and reaction rate have been studied by various research groups, but detailed combustion mechanisms still require a large amount of computing power. Simplified combustion mechanisms have been introduced in this study to estimate reaction rate and products from catalytic combustion. The mechanisms have been chosen based on the main reaction path. 2D and 3D simulations in ANSYS-Fluent have been studied to validate simplified combustion mechanisms with detailed combustion mechanisms and to observe the surface coverage of carbon monoxide, vacant sites and oxygen. Results show that simplified combustion mechanisms can be used to estimate reaction rate and products from combustion with reasonable surface coverage species by reducing the number of reaction mechanisms; however, simulation results are slightly off at high temperature. These simplified combustion mechanisms are useful when computational power is insufficient.

View full abstract

Most of professional and industry sectors, including architecture, are expected to gain digitalization impact in a specific and subtle form to embrace the Fourth Industrial Revolution and later also the Society 5.0 era. Several technologies, such as Building Information Modeling (BIM), Internet of Things (IoT) and Virtual Reality (VR), have been developed on aiding stakeholders of building project, including architect. BIM and IoT technology open a possibility binding a building as a physical entity with its digital model or known as Digital Twin. But to bring it to virtual environment with VR, additional interaction model is required to developed. In this research, we explore the interaction model inside a VR environment with a BIM model as a digital entity connected with its physical counterparts connect to the model through IoT devices simulated as real-time cloud database. The interaction model is called ‘Connected Digital Twin’ or CDT and it is implementable in operational/maintenance phase. Also, it opens a possibility to expand the implementation to earlier phases of a building lifecycle on future research.

View full abstract

Nanoparticles are being applied for various uses, and their antimicrobial properties are increasingly explored as a green approach to tackling plant pathogens. Fungal diseases are one of the leading causes of crop destruction and the antifungal effect of ATZ nanoparticles, a combination of silver nitrate, titanium dioxide and zirconium dioxide, against phytopathogenic fungi is reported in this research. The aim of this study was to investigate the effect of ATZ nanoparticles on mycelial growth and spore germination of Colletotrichum gloeosporioides, a causal agent of anthracnose disease of chili seed. Potato dextrose agar (PDA) incorporating ATZ nanoparticles at the concentrations of 2, 4, 6, 8 and 10 % w/v significantly delayed mycelial growth, and 6-8% completely inhibited spore germination. Whereas, at 2 and 4% caused significant reduction in the spore germination compared with control. Pre-treatment effect of ATZ nanoparticles on anthracnose disease and chili seed quality was determined for 0, 1, 2 and 3 months respectively. Artificial inoculated chili seeds were treated with 2 and 4% w/v ATZ nanoparticles compared with 0.15% w/v captan (fungicide) treated seeds and non-treated seeds. The results revealed that nanoparticles of 2% w/v ATZ showed the best results to suppress the seed infection and improve the chili seed quality as indicated by percentage of seed germination, germination index, mean germination time and growth rate of chili seedlings compared to the other treatments. Therefore, the application of ATZ nanoparticles appeared very important to improve the seed quality.

View full abstract

The objective of this study was to investigate the extraction of pectin from dragon fruit (Hylocereus undatus) peels under different extraction methods (ultrasound assisted extraction method, UAE and conventional extraction method, CE). In this study, UAE significantly improved the production yield when comparing to CE. The pectin extracted with UAE at 2.5W/g for 15 min had the highest yield (19.31%), which was higher than that extracted with CE (15.64%).The pectin obtained from UAE (2.5W/g for 15 min) and CE was compared with the commercial citrus pectin in terms of physicochemical properties and chemical structures. The equivalent weight (EW), degree of esterification (DE), methoxyl content (Met), total anhydrouronic acid (TAA), FT-IR, and DSC results revealed that UAE and CE pectin could be categorized as low-methoxyl pectin (LMP), and showed slightly similarity to those of commercial citrus pectin. The present study demonstrated that dragon fruit pectin was identified as an alternative source of the commercial pectin.

View full abstract