ASEAN Journal on Science and Technology for Development

Suitability of Current Single-Cylinder Diesel Engines Available in Indonesia with New Indonesian National Standard (SNI 119:2020)

2022-08-02T10:40:41+07:00

Diesel engines have been utilized for various purposes in Indonesia. Diesel engine manufacturers have developed designs and competed with each other to win the market in Indonesia. Nationally and internationally recognized standards are required to ensure the quality of products for Indonesia and the international market. The Indonesian National Standard (SNI) 119 is one of the recognized standards for single-cylinder diesel engine in Indonesia. Compared with the previous SNI 0119:2012, SNI 119:2020 has revised the limits of some parameters. This study evaluated the passing data of SNI test results from 2015 to 2020 and then analyzed the distribution of engines in each class for the comparison of limits between SNI 0119:2012 and SNI 119:2020 using normal distribution. Results showed that class D engines have the highest probability of passing the new limit of SNI 119:2020 at 98.59% to 100%. Meanwhile, class B has the lowest probability of acceptance at 38.68%. Power is the test parameter with the highest level of suitability, and specific fuel consumption is the parameter with the highest level of discrepancy for changes in SNI 119:2020.

Analysis of Surface Water Availability to Meet Agricultural Water Demands in Kediri Regency, Indonesia

2022-06-24T13:14:13+07:00

This study aims to analyze the potential of surface water to meet agricultural water needs in Kediri Regency, Indonesia. Data from government agencies (i.e., Indonesian Bureau of Meteorology, Climatology, and Geophysics and Kediri Agriculture Office) and fieldwork were analyzed to achieve the research objectives. The data obtained consisted of rainfall, temperature, infiltration capacity, soil texture, root depth, and agricultural land area. The potential of surface water resources was calculated by using the Thornthwaite–Mather water balance method. The water balance results were compared with agricultural water demands, which were calculated on the basis of the area of agricultural land and type of crop, particularly paddy fields. Critical and noncritical conditions for surface water resources were classified on the basis of the ratio between the availability of surface water resources and the demand for agricultural water. Results showed that the total surface water potential widely varied by season. The water balance calculation indicated that all subwatersheds (SWs) experienced a water surplus in the rainy season, whereas almost all SWs were deficient in surface water in the dry season, Overall, the surface water in Kediri was critical in the rainy season and more severely critical in the dry season. The results of this study indicated that the high demand for agricultural water can affect the availability of water resources in the tropics. The results are expected to be considered in determining regional planning related to the use and need of water resources and supporting infrastructures.

Manuka Honey Reduces the Virulence of Pectobacterium brasiliense by Suppressing Genes That Encode Plant Cell Wall-Degrading Enzymes

2022-09-19T09:31:25+07:00

The primary virulence of soft rot pectobacteria, including Pectobacterium brasiliense, is mainly determined by the massive production of plant cell wall-degrading enzymes (PCWDEs), which promote plant tissue maceration in many crops. The antibiotic treatment to treat bacterial soft rot causes environmental problems and potentially affects resistance. Antibiotic resistance is driving interest in antimicrobial treatments, and no organism has been reported to have acquired resistance to honey. However, the use of honey as a therapeutic agent for plant bacterial pathogens has rarely been studied. Therefore, this study was undertaken to determine the in vitro effect of Manuka honey against P. brasiliense at the phenotypic and genotypic levels. A sublethal concentration of honey was determined by a growth inhibition assay in broth medium containing different concentrations of Manuka honey. A macerating assay was performed on orchid leaves, and the activities of the PCWDEs were examined in plate assays. The expression of PCWDE-associated genes was investigated using semi-quantitative reverse transcription-polymerase chain reaction analysis. The exposure of P. brasiliense to a sublethal concentration of Manuka honey significantly decreased the maceration ability of the orchid and the synthesis of PCWDEs, i.e., pectate lyase, polygalacturonase, and protease. Moreover, five PCWDEs-encoding genes, such as pelA, pelB, pelC, pehA, and prtW, had lower expression levels after the honey treatment compared with recA as the internal standard. The honey treatment decreased the virulence of P. brasiliense associated with the synthesis of PCWDEs. Therefore, Manuka honey reduced virulence by suppressing the expression of the PCWDE genes.

Mechanical and Thermal Load Effect on Piston Crown of a Biogas Engine: A Simulation Approach

2022-10-13T14:39:32+07:00

This paper presents the study results on stress and deformation of the piston crown of a biogas engine converted from a conventional diesel engine using dedicated software. The original diesel engine was modified to reduce the compression ratio to suit biogas fuel. The original engine's combustion chamber and compression ratio were changed by modifying the piston crown to a heron type. The parameters of in-cylinder pressure and temperature were determined by the thermodynamic simulation software AVL Boost. Research results show that the in-cylinder pressure decreased compared to diesel when using biogas fuel, but the temperature increased. The infinite element method-based software was used to simulate the effects of mechanical and thermal load on stress and deformation on the piston crown of the biogas engine. As modeling with maximum pressure and temperature, the maximum stress on the piston crown was 3.425x10⁹ N/m² and 4.224x10⁹ N/m² for diesel and biogas. However, the maximum deformation in the biogas case was lesser than diesel, 0.3037 and 0.4186 mm. The minimum safety factor was 0.1012 and 0.0891 for diesel and biogas models, respectively.

Stochastic gradient boosting for urban change detection using multi-temporal LANDSAT-5TM in Yogyakarta, Indonesia

2022-11-07T14:03:35+07:00

Despite available remote sensing data, technical challenges in developing countries have hindered local urban authorities from updating periodic land cover maps. Therefore, this study proposed a practical approach for regions with insufficient ground truth data. The study implemented a machine learning algorithm using single date medium spatial resolution data to build a classifier for separating Urban and Non-Urban zones. Then, the classifier was employed on multiple dates in 1999, 2005, and 2011 to corroborate its robustness. Results showed the stochastic gradient boosting (SGB) algorithm succeeded in building a robust classifier using the digital number value of LANDSAT-5TM 2005 with an overall accuracy of 0.76 and an area under curve receiver operator characteristic (AUC-ROC) value of 0.83. Moreover, the classifier predicted that urban areas in Yogyakarta, Indonesia, reached 24,099 (hectares) ha; 26,598 ha; and 22,650 ha in 1999, 2005, and 2011, respectively. The classifier's performance in predicting multiple datasets combined with histogram matching of medium spatial resolution data showed satisfactory results comparable to reference data from Statistics Indonesia, indicating sufficient accuracy for areal-integrated multi-temporal urbanization monitoring.