This study examines the impact of students’ anxiety, due to online learning, in different learning environments: a synchronous (Zoom) and asynchronous learning environment (YouTube) to compare students’ conceptual understanding of electric circuits. Multiple linear regression and factor analyses were conducted to examine the factor of students’ anxiety and conceptual understanding. A sample of 99 vocational students participated in the study, including YouTube (n = 49) and Zoom (n = 50) groups. The DIRECT was used to diagnose test for conceptual understanding in the electric circuits, and OTAI was used to assess anxiety in online learning test. The OTAI consists of three factors: psychological, physiological, and online. The results showed that students’ anxiety, in some factors, affected their conceptual understanding of the electric circuits in both groups. However, there was a significant increase in conceptual understanding in both treatment groups. Although the students’ conceptual understanding had a slight increase, online learning has to improve to reduce the anxiety of learners.

The lifetime of a cast-resin transformer mainly depends on the condition of insulation material. Partial discharge (PD) is an important reason for insulation deterioration in cast-resin transformers. Identifying the position of PD is very necessary for damage assessment while the transformer is still operating, and the transformer is covered by housing. This paper proposes the investigation of a cast-resin transformer using an AE sensor and HFCT sensor to specify the precise source of PD. In this study, four AE sensors were used to find PD sources, and the high-frequency current transducer (HFCT) technique was used to identify the PD source and the criteria level. The experiment, in the first two parts, identified the possibility of PD, which includes the position of PD. The final part of the experiment verified the position of the PD source of a cast-resin transformer and confirmed the inspection results. AE and HFCT sensors can be used to detect the location of PD sources, confirming the position of the PD source by sensor detection. In addition, the evident partial discharge picture on the insulator surface of high voltage side. The process successfully and accurately identifies and locates the PD source.

This study used the Area Elimination Method (AEM) of transformer design with transformer characteristic simulation. The multidimensional variable of physical parameters such as magnetic density, current density, voltage and coil turn was performed. This method was used in designing the 8000 kVA 22,000–3300/1905 V oil-type large distribution transformer. The result from a design found that the objective function tries to reduce the material to be used, and less core steel, less conductors, less transformer oil or less transformer tanks may cause an increasing load loss or increasing temperature rise, but we have calculated the temperature in the winding and design the radiator fins at the same time. After designing the transformer with AEM and it being manufactured in the production process, the transformer was tested according to IEC standards. It was confirmed that the power loss tests with no load yielded lower power loss than the standard value. In addition, the transformer passed the satisfaction test and the results of this design were built and tested with IEC 60076 standards. The information from the design using the Area Elimination Method could be a guarantee of standardized accuracy for oil distribution transformers. This also saves time and increases design efficiency for transformer designers.

This study was aimed to present a Technical loss analysis of the Provincial Electricity Authority (PEA) in Hatyai. To determine the technical loss in the distribution system included are Transmission Line Losses, Power Transformer Losses, Distribution Line Losses and Lowvoltage Transformer and Distribution Line Losses. It was found that Low-voltage Transformer and Distribution Line Losses had a maximum value of 79 % and Technical loss was at 3.43. So in controlling or decrease Technical loss, the appropriate and correct method had to be selected by investigating both cost and worth. This study was also to determine distribution line losses by electrical model and to report on the power losses evaluation method as an improvement method to reduce the investigation cost for both transformer and capacitor selection. The study further aims at increasing the efficiency and reliability of the distribution system by reducing Technical Losses by increasing feeder size, power factor correction, reducing feeder impedance, lower transformer losses. It was discovered that line losses have much value at the end line. This was found to decrease when loads have constant distribution and are near the source. That is, line losses have lower value when lead lines have a larger size. Both load distribution and lead line sizes were observed to affect distribution line losses.

The typical household uses dish detergent, laundry detergent, and other synthetic detergents that contain large amounts of surfactants. For example, in the laundry case, it is common to use a combination of detergents and fabric softeners, and the anionic surfactants contained in the detergent and cationic surfactants contained in the fabric softener is bonded together to create a condition where surfactants do not decompose easily in aqueous solutions. As a result, surfactants that are drained into the water without degradation can cause environmental damage and pollution to ecosystems, oceans, and waterways. In this study, an aqueous solution containing anionic surfactants was treated by an atmospheric-pressure non-equilibrium microwave discharge plasma jet using an Ar gas and an Ar + H-2 mixture gas to enable decomposition of the surfactants in the aqueous solution by the OH and H-2 radicals given off in the plasma.

This analysis used the cathode spot model to describe the physical mechanism of the thermal conductivity effect on the instability phenomena. An analysis of stable arc current is performed by changing the thermal conductivity of copper by compound material. The minimum stability arc was found to be inversely proportional to the thermal conductivity. Low thermal conductivity is more critical in a more stable arc than a high thermal conductivity cathode material. The thermal conductivity is reduced to increase stable arc current by reducing reversed electrons from the plasma region. These results were similar to the obtained data, indicating that this analysis by the cathode spot model, which is used to investigate the thermal conductivity effect in low-current vacuum arc, may be valid for volatile materials.