Vol. 56 No. 3 (2024)

The liquefaction that occurred in the city of Palu on September 28, 2018, was caused by a series of significant earthquakes that took place in a relatively short time around 25 minutes after the main earthquake of magnitude 7.5. This event was followed by aftershocks of magnitudes 6.4, 6.2, and 6.1. The magnitude 6.2 aftershock occurred at 10.16 UTC, while the magnitude 6.1 aftershock occurred at 10.25 UTC. These were both located very close to the liquefaction locations in Balaroa, Petobo, and Jono Oge. We investigated the mainshock and the three aftershocks using the NCEER method based on…

The Instrumented Charpy impact test is a promising method for determining a material’s impact response. Stainless steel has higher impact energy absorption capacity, high tensile, and yield strength compared to aluminum. Performance varies among grades; for instance, Aluminum 7075-T6 exceeds Aluminum 6061-T6 in tensile and yield strength. However, information regarding their energy capacity and impact signal pattern is lacking. This study investigated the impact properties using a Charpy machine, a data acquisition system, and a sensing element. Strain gauges were used to record the impact…

In response to the issue of high tomato yield, low efficiency in harvesting tomatoes grown in greenhouses, and low recognition accuracy of nighttime harvesting robots, a design was developed and a robotic system was created specifically for nighttime greenhouse tomato harvesting. The robot employs a vision system and YOLOv5+HSV fusion algorithm to recognize and locate tomatoes. It then transmits this information to the robotic arm. By coordinating the visual system, the robotic arm, the end effector, and the lifting mechanism, the robot accurately picks ripe tomatoes. The robot was subjected…

In view of the development trend of rail vehicles towards higher operating speed and low power consumption, a scheme for a lightweight rail vehicle body is proposed, based on sensitivity analysis. Using topology optimization of the vehicle body section structure, finite element models of the vehicle body section structure under single working conditions and multiple working conditions were established, respectively, and the force transmission path of the vehicle body structure under different working conditions was obtained under different working conditions. The topology of the…

This work analyzed the interactions between gate oxide thickness (Tox), voltage dependence, and electron mobility (E-mobility) in the inversion layer, which controls the electron movement properties of 4H-SiC/SiO2. This paper also presents a calculation of gate oxide thickness in correlation with gate voltage mainly for high-voltage applications. The results of this work revealed that at low resistance, E-mobility increases with gate voltage and oxide thickness, which saturates at the point of value. Coulomb scattering and surface phonons at the inversion region of SiC MOSFETs are regarded as…

The performance of an underground station structure subjected to an earthquake can be evaluated by looking at deformation as well as forces and bending moments that occur in the structure. Most design practices adopt simplified approaches, such as the free field deformation method and pseudo-static approaches, which have a high level of uncertainty. Therefore, it is necessary to perform dynamic time-history analysis to verify the results of the simplified approach. Dynamic modeling is considered a more appropriate approach because it better represents seismic shaking in evaluating the seismic…

Spontaneous fermentation is becoming ever more elusive because of vast natural microbiota profiles that affect geographical region, climate, and applications of agrichemicals. This study aimed to identify the physicochemical and sensory properties of local planted (Serdang, Malaysia) Robusta (Coffea canephora L.) coffee beans after undergoing different spontaneous wet fermentation (SWF) periods i.e., 0 days as control, 3 days, and 5 days. The hardness decreased significantly (p < 0.05) by 80 to 90% in roasted fermented roasted Robusta coffee (FRRC) beans. The carbohydrate content was…

This paper outlines an optimized propeller design for an unmanned aerial vehicle (UAV) employing a Kriging surrogate model-based optimization approach. The primary objective was to maximize propeller efficiency while adhering to the thrust-to-torque ratio constraint at a rotational speed of 6,500 rpm. The design variables encompassed the twist angle and the ratio of blade thickness to chord length across the twenty-section airfoil of the propeller. A comprehensive analysis was conducted using computational fluid dynamics to assess the aerodynamics of the propeller. The Kriging surrogate model…

Online public opinion incidents in universities occur from time to time, with the source difficult to find, rapid dissemination, and escalating fragmentation. There are many problems and difficulties in the guidance of online public opinion in universities, and a new way out needs to be explored. This article explores the influencing factors of intelligent robots on online education in universities in the all-media era. This article believes that the ecology of university online education is an inherent component of university online culture and is the result of the interaction and mutual…

This paper presents train modeling used in a simulator platform for driver training. It was developed for the CC203/CC204 locomotive. The driver will gain experience as in a real locomotive from the perceived platform movements if the movements match real conditions as accurately as possible, including the distance travelled. To this aim, a longitudinal model of the train was developed based on measurement data obtained from the Argo Parahyangan train traveling from Bandung to Jakarta. A second-order linear time invariant model was obtained by a black box identification approach, in which the…

Cover Vol. 56 No.3, 2024

Front Matter

Back Matter