Search Results

Journal ID : TRKU-19-07-2023-11548
Total View : 7

Title : Age Assignment of the Outcrop along Prataan River, Tuban, East Java, based on Calcareous Nannofossil and Foraminifera Assemblages

Abstract :

The geological age of the outcrop along the Prataan River were interpreted based on calcareous Nannofossil and Foraminiferal assemblages. The lithological unit recognized in this area, from oldest to youngest are Ngrayong-Bulu, Wonocolo, Ledok and Mundu Formations. In this study, 23 samples of 15 sample locality were analyzed; 23 species of calcareous Nannofossils and 20 species of planktic Foraminifera were identified. Based on calcareous Nannofossil, the Ngrayong-Bulu, Wonocolo, Ledok-Mundu Formations are NN7 or middle Miocene, NN10 or late Miocene, NN14-NN15 or early Pliocene in age, respectively. Based on planktic Foraminifera, the Wonocolo is N16 or late Miocene, and Ledok-Mundu Formations is N18-N19 or Pliocene in age. Correlating the section's composite column of Prataan River with well TPN-1, revealing that the middle-late Miocene unconformity and the late Miocene-early Pliocene unconformity discovered in the well are predicted to be existed in the Prataan River outcrops.

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Journal ID : TRKU-26-06-2023-11547
Total View : 9

Title : Fracture Behavior of a Dissimilar Weldment Comprising Duplex Stainless Steel and Low Alloy Steel

Abstract :

This investigation characterizes the fracture behavior of a dissimilar weldment comprising E2209 duplex stainless steel as a weld metal and the low alloy steel 20MnMoNi55 as a base metal. The microstructure of the base metal consisted of bainitic structure while the weld metal comprised ferrite and austenite phases. Instrumented impact testing was employed to determine the fracture behavior at temperatures between -196 and 300 C. The results showed that the base metal and the duplex weldment exhibited distinct ductile to brittle fracture transition behavior. The base metal displayed much higher upper shelf energy (USE) level than that of the duplex weldment (130 vs. 80 Joule), designating superior resistance to ductile fracture at high test temperatures. By contrast, the duplex weldment exhibited a greater deal of resistance to brittle fracture at low test temperatures. That was manifested by a lower value of the ductile to brittle transition temperature (DBTT) of the duplex weldment against that of the base metal (-75 vs. 25 C). In addition, the brittleness temperature (the temperature at which complete brittle fracture features prevail) was much less for the duplex weldment than the base metal (-100 vs. -25 C). Furthermore, the cleavage fracture stress as computed from the dynamic yield strength values determined at the brittleness temperature gave values of 2650 and 1890MPa for the duplex weldment and the base metal, respectively. The results were substantiated by the load–time traces, derived from the instrumented impact tests at different temperatures as well as the pertinent fracture surface morphologies.

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Journal ID : TRKU-13-06-2023-11546
Total View : 1

Title : Thermally Induced Embrittlement of the Pressure Vessel Steel A533-B

Abstract :

The pressure vessel steel A533-B used in the nuclear power reactors was heat treated to simulate thermal circumstances similar to those that could develop during a loss of coolant incident. The applied heat treatment resulted in phase transformation of the steel from tempered bainite structure into untempered lath martensite structure. The impact properties of the steel in the as-received condition and after heat treatment were evaluated. The results showed that the as- received steel has experienced serious degradation in the impact properties after exposure to heat treatment. The ductile to brittle transition temperature increased by 100oC and the upper-shelf energy was lowered by 30%. Room temperature impact test results showed 100% ductile fracture behavior of the steel with a total fracture energy of 200 J. After heat treatment, the steel displayed 100 % brittle fracture behavior with a total fracture energy of 12 J. Load-time curves of the instrumented impact tests showed that the decrease in the impact fracture energy was mainly due to the decrease in the fracture propagation energy than in the fracture initiation energy. Fracture surface morphology of specimens tested at room temperature revealed ductile microvoid coalescence fracture features for the as-received steel and brittle cleavage fracture features for the steel after exposure to heat treatment. The resulted embrittlement of the steel was discussed in relation to the phase transformation of the steel microstructure in consequence of the applied heat treatment.

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Journal ID : TRKU-28-04-2023-11545
Total View : 3

Title : Bibliometric Analysis: The Surface Modification of Activated Carbon in Increasing the Adsorption of Organic and Inorganic Pollutants

Abstract :

Activated carbon adsorption has been widely used as an alternative environmental treatment to reduce metal ions, but it is less effective against heavy metals and other pollutants, including organic and inorganic compounds. Surface modification is required to increase the adsorption of activated carbon. To build up the information related to adsorption power of activated carbon modification, this study evaluated the theme relevant to adsorption of activated carbon modification using keywords "activated carbon" and "surface modification" as the data input. The database utilized for bibliometric analysis in this study was from Scopus with the help of VOSviewer software for network visualization of authorship, countries, citations, affiliations, and keywords. The analysis was carried out on February 3, 2022. The author limited the data by its year from 2013 to 2020 and the result was 262 documents. The results portrayed that the publication of activated carbon modification has been highly rocketing in the last eight years, specifically from 2019 to 2021. China is the leading country in activated carbon modification research, which results in the highest publications, most cited authors, and affiliations. Additionally, Elsevier is a publisher with the most top publications in producing activated carbon modification research articles. The keyword analysis showed that the studies related to activated carbon modification were mostly concentrated on characteristics of activated carbon, surface characteristics, adsorption, and environmental treatment. This bibliometric analysis study presented the relevant information on the surface modification of activated carbon to boost dangerous pollutant adsorption in the direction of environmental treatment.

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Journal ID : TRKU-13-02-2023-11541
Total View : 17

Title : Site-Specific Nutrient Management for Paddy Fields – Integration of Fertilizer Recommendation Formula into GIS

Abstract :

MARDI developed the RiceFert formulation to assist in fertilizer recommendation rate for optimal paddy growth. The formulation followed an adjustable soil test–target yield equation (ST-TY) into dedicated software. The output from the RiceFert software includes a total rate of N, P2O5, and K2O fertilizer (kg/ha) and split application or straight fertilizer rate (kg/ha). Additionally, the output from RiceFert was integrated to GIS to produce maps according to the specific fertilizer recommendation rates. With interpolation techniques, thematic maps added more information, such as total area coverage according to individual classification classes. This paper discusses the overall process of fertilizer recommendation rate for paddy fields, starting with the RiceFert formulation, followed by map production using interpolation techniques according to the fertilizer recommendation output. The RiceFert strategy is expected to benefit local authorities because it offers vital information to farmers for optimal rice growth and output.

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