bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quasi-normal modes of loop quantum black holes formed from gravitational collapse
Authors: Zhang Chao , Wang Anzhong 
Published: October 2024

Abstract
In this paper, we study the quasi-normal modes (QNMs) of a scalar field in the background of a large class of quantum black holes that can be formed from gravitational collapse of a dust fluid in the framework of effective loop quantum gravity. The loop quantum black holes (LQBHs) are characterized by three free parameters, one of which is the mass parameter, while the other two are purely due to quantum geometric effects. Among these two quantum parameters, one is completely fixed by black hole thermodynamics and its effects are negligible for macroscopic black holes, while the second parameter is completely free (in principle). In the studies of the QNMs of such LQBHs, we pay particular attention to the difference of the QNMs between LQBHs and classical ones, so that they can be observed for the current and forthcoming gravitational wave observations, whereby place the LQBH theory directly under the test of observations.
Scrutinizing black hole stability in cubic vector Galileon theories
Authors: Felice Antonio De , Kase Ryotaro , Tsujikawa Shinji 
Published: October 2024

Abstract
In a subclass of generalized Proca theories where a cubic vector Galileon term breaks the U(1) gauge invariance, it is known that there are static and spherically symmetric black hole (BH) solutions endowed with nonvanishing temporal and longitudinal vector components. Such hairy BHs are present for a vanishing vector-field mass (m=0) with a non-zero cubic Galileon coupling β
3. We study the linear stability of those hairy BHs by considering even-parity perturbations in the eikonal limit. In the angular direction, we show that one of the three dynamical perturbations has a nontrivial squared propagation speed c

Ω,1

2, while the other two dynamical modes are luminal.
We could detect two different unstable behaviors of perturbations in all the parameter spaces of hairy asymptotically flat BH solutions we searched for. In the first case, an angular Laplacian instability on the horizon is induced by negative c

Ω,1

2. For the second case, it is possible to avoid this horizon instability, but in such cases, the positivity of c

Ω,1

2 is violated at large distances. Hence these hairy BHs are generally prone to Laplacian instabilities along the angular direction in some regions outside the horizon. Moreover, we also encounter a pathological behavior of the radial propagation speeds c

r
possessing two different values of c

r

2 for one of the dynamical perturbations. Introducing the vector-field mass m to cubic vector Galileons, however, we show that the resulting no-hair Schwarzschild BH solution satisfies all the linear stability conditions in the small-scale limit, with luminal propagation speeds of three dynamical even-parity perturbations.
High-resolution Observations of Clustered Dynamic Extreme-Ultraviolet Bright Tadpoles Near the Footpoints of Corona Loops
Authors: Wang Rui , Liu Ying D. , Chitta L. P. , Hu Huidong , Zhao Xiaowei 
Published: October 2024

Abstract
An extreme ultraviolet (EUV) close-up view of the Sun offers unprecedented detail of heating events in the solar corona. Enhanced temporal and spatial images obtained by the Solar Orbiter during its first science perihelion enabled us to identify clustered EUV bright tadpoles (CEBTs) occurring near the footpoints of coronal loops. Combining SDO/AIA observations, we determine the altitudes of six distinct CEBTs by stereoscopy, ranging from ∼1300 to 3300 km. We then notice a substantial presence of dark, cooler filamentary structures seemingly beneath the CEBTs, displaying periodic up-and-down motions lasting 3–5 minutes. This periodic behavior suggests an association of the majority of CEBTs with Type I spicules. Out of the ten selected CEBTs with fast downward velocity, six exhibit corrected velocities close to or exceeding 50 km s−1. These velocities notably surpass the typical speeds of Type I spicules. We explore the generation of such velocities. It indicates that due to the previous limited observations of spicules in the EUV wavelengths, they may reveal novel observational features beyond our current understanding. Gaining insights into these features contributes to a better comprehension of small-scale coronal heating dynamics.
Bas KiTE PHEB Analysis Performance using MATLAB/SIMULINK
Authors: Aiman W. A. W.M , Norbakyah J. S. , Anida N. I , Zulfadli M. , Salisa A. R. 
Published: October 2024

Abstract
The performance analysis of Bas KiTE Plug-in Hybrid Electric Bus (PHEB) is crucial for assessing its effectiveness in power system applications to reduce fuel consumption and emission. In this study, MATLAB/SIMULINK is employed as a tool of modelling and simulation to evaluate the performance of Bas KiTE PHEB model. The research focuses on sizing of Bas KiTE PHEB and performance of Bas KiTE PHEB electric machine model, internal combustion engine model, and energy system storage model using MATLAB/SIMULINK in term power, fuel consumption and emission. Kuala Terengganu driving cycle were use as input to see the performance. Through this study, the preliminary of Bas KiTE PHEB model use MATLAB/SIMULINK can be used as reference to build the prototype of PHEB in Kuala Terengganu.
Alternative Off-Site Power Supply During Extended Station Blackout for Future Nuclear Power Plants in Indonesia
Authors: Hakim Arief Rahman , Saputro Rakhmat Eko 
Published: October 2024

Abstract
The study explores the diverse and flexible coping (FLEX) strategy on a conventional large nuclear power plant connected to an alternative off-site power. Indonesia is one of the countries with the highest natural hazards in the world, so the newly-built NPPs are susceptible to station blackout (SBO) accidents one of the highest contributors to the core damage frequency (CDF). The study proposes a dedicated, independent, and direct electrical connection between a pressurized water reactor to a nearby hydropower plant as the alternative off-site power supply during the extended SBO. The study shows that the proposed strategy successfully reduces the SBO frequency by 90%—a net 33% CDF reduction without a major modification to the existing PWR design.
Analysis of Biomass Co-firing Combustion Test using Corn Cobs at Punagaya CFPP as A Green Energy Alternative
Authors: Ardiansyah R R , Dian J , Rhamadhan F Z 
Published: October 2024

Abstract
Indonesia is determined to reduce fossil fuels by 2060 set a national renewable energy mix target of 23% by 2025 and be free of fossil fuels by 2060. One of the PLN’s (a national electrical company in Indonesia) efforts to increase carbon emissions reduction and strengthen local new renewable energy is co-firing biomass on CFPP. Indonesia, which is located in a tropical area, has a large potential for biomass resources. Corn cob, one of the biomass types, has a big potential to replace coal as fuel in CFPP especially in Jeneponto Region, South Sulawesi. By utilizing corn cobs as a fuel with a co-firing mechanism, it can generate green energy. The methodology for assessing the corn cob co-firing combustion test’s performance at Punagaya CFPP is presented in this paper. It is based on a multi-criteria assessment designed to examine the technical, financial, and environmental effects of operating parameters with a mixture composition of 95% coal and 5% corn cobs at 70 MW load for 10 hours. From the test results in terms of operational aspects, the parameters have changed but it still in the normal operating range; FEGT increased by 5.3°C, bed temperature increased by 8.9°C, air chamber pressure decreased by 0.05 kPa, and total airflow decreased by 4.5 T/h. From the financial aspect, it has benefited from a decrease in the value of Specific Fuel Consumption (SFC), which is 0.014 kg/kWh compared to 100% coal. From the environmental aspect, the overall results of emission parameters are still by environmental quality standards and have decreased for NOx and SO2 parameters.
Investigation of ash problems potential for a blend of high-sulfur coal and bamboo pellet biomass
Authors: Ghazidin H , Suyatno  , Ruhiyat A S , Kuswa F M , Winangun K , Putra H P , Karuana F , Prismantoko A , Adelia N , Prayoga M Z E , Hariana  
Published: October 2024

Abstract
Biomass bamboo can be utilized as co-firing fuel in power plants in order to provide more green energy. However, the characteristics of biomass bamboo with high potassium and chlorine that probably increase ash problem aspects need to be investigated before the implementation. This study aims to obtain an initial prediction of slagging, fouling, abrasion, and corrosion for bamboo pellets and high-sulfur coal blends using empirical indices. This study used seven slagging parameters, four fouling parameters, one abrasion parameter, and two corrosion parameters. The result shows that a composition of 10-30 wt.% bamboo pellets is more recommended than others. Despite the composition of 50 wt.% and above being predicted to reduce the slagging risk of high-sulfur coal, the composition of 40 wt.% and above is predicted to increase the fouling risk. At higher compositions, 80 wt.% and above are predicted to increase the corrosion risk. Further test using a drop tube furnace is necessary to obtain comprehensive results. Moreover, the calorific value aspect needs to be considered depending on the need of the power plant for the efficiency aspect.
Synthesis of bio-hydrocarbon fuel using Ni and Co based catalyst on Indonesia natural zeolite
Authors: Wijaya G H A , Ramadhita H , Dwiatmoko A A , Simanjuntak F S H 
Published: October 2024

Abstract
Through a deoxygenation reaction, fatty acid-containing biomass resources including palm fruit, palm kernels, and soybeans can be converted into green diesel (bio-hydrocarbon). In this study, low-cost Indonesia natural zeolite was utilized as catalyst support for nickel, cobalt and a nickel/cobalt mixture. All prepared catalysts were used as catalyst for bio-hydrocarbon production via deoxygenation of fatty acid. The catalytic activity of each catalyst in the production of bio-hydrocarbon from fatty acid was investigated. Selectivity of each catalyst to hydrocarbon products, heptadecane, heptadecene, octadecene, and octadecane was studied as well. The results showed all prepared mono- and bi-metallic catalyst exhibited high conversion of fatty acid, more than 90% with a different yield of biohydrocarbon.
Modification of activated carbon through chemical-physical activation method with KOH and 60Co gamma irradiation from banana leaf waste
Authors: Ariyanti Dhita , Siagian Augie Davin , Swantomo Deni , Permana Sidik 
Published: October 2024

Abstract
Until now waste is still a problem in many big cities in Indonesia. In addition, the amount of waste increases as the population increases. Banana leaf waste is no exception, which is included in other types of waste, which accounts for 6.33% of the total waste in Indonesia in 2022. Utilization of banana leaf waste as a raw material for activated carbon production can also be an alternative to reducing the amount of wasted banana leaf waste because they contain various kinds of organic compounds. Activated carbon is widely used as an adsorbent in various sectors, especially in the industrial sector. Production of activated carbon must go through an activation process to enlarge the surface pores either chemically or physically, or even both. This study aims to compare the results of activated carbon surface area and functional groups using the chemical-physical activation method from banana leaf biomass raw materials with KOH and gamma irradiation at various doses. The research method used is an experimental method consisting of 4 stages: dehydration, carbonization, activation, and characterization. The research was started by dehydrating the leaves and continued with the carbonization stage at 350°C for 30 minutes. Carbon was divided into four samples that consisted of 1 blank and 3 test materials that activated with 30% (w/v) KOH solution for 24 hours and gamma-irradiated with a dose of 10, 30, and 50 kGy. Results were characterized using FTIR and BET. The effect of gamma 60Co irradiation on the activated carbon material from banana leaf waste can increase the peak transmittance value of the activated carbon functional group due to the formation and reaction of free radicals on its surface. Increase in the surface area (from 6.504 to 24.04 m2/g) is also associated with an increase in the absorbed dose due to the formation of more free radicals. However, the surface area obtained is not as expected due to the possibility of pore blockage and excessive activation time, which causes the surface area of the material to be small.
The Concept of Educational Park for Introducing Micro Hydro Energy in Rural Communities (The Case Study of Lalumpe Village in Indonesia)
Authors: Rumbayan Meita , Sompie Sherwin R.U , Tangkuman Stenly , Abast Kristifania , Rumbayan Rilya 
Published: October 2024

Abstract
This progress report highlights research on micro hydro technology as a renewable energy solution for a remote rural community in North Sulawesi, Indonesia. Focused on Lalumpe village, situated along the remote coastal region of Minahasa, the study identifies the Tulaun river as a potential resource to develop an educational park for introducing micro hydro energy. With energy being crucial for quality living in urban and rural areas, this research employs a literature review, data collection, and reserve engineering method to assess the feasibility of an educational park as a showcase for micro hydro energy. This report serves as a reserve engineering for the concept of an educational park in Lalumpe village, providing recommendations based on information extracting, modelling, and a review. These insights contribute to scenario development and a guideline for successfully implementing micro hydro technology as an educational park, thus empowering rural communities with sustainable energy solutions.
Synthesis and Characterization of LaMnO3 Prepared by Hydrothermal Synthesis Method
Authors: Febrianti Y , Dewi N N E , Purwanto A , Dimyati A , Kurniawan B 
Published: October 2024

Abstract
LaMnO3 powders were prepared by hydrothermal synthesis method by varying citric acid to metal ions. The ratio of citric acid to metal ions is one of the parameters that have an affect on purity of LaMnO3 prepared by hydrothermal method. It is necessary to control the parameter to obtain the good quality of the final product of LaMnO3. LaMnO3 with variation molar ratio of citric acid to metal ion (CA/M) of 0, 1 and 4 were prepared. To determine the morphology, crystall structure, and phase composition, the powders were characterized by Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and X-Ray Diffraction (XRD) techniques. The obtained results revealed that the morphology of sample CA/M = 0 has rod-like shape, CA/M = 1 was in the formed of irregular fine particles that stuck together and formed agglomerates, while the spherical morphology with various diameters were formed in the sample CA/M = 4. The XRD analysis demonstrated that sample CA/M = 1 had a single phase while in sample CA/M = 0 and CA/M = 4 others phase were detected such as La (OH)3 and La2O3. There was a change in crystall structure of the LaMnO3 phase in each sample due to the presence of citric acid. The peaks position in sample CA/M = 0, 1, dan 4 exhibit orthorhombic, rhombohendral and cubic structure with space group of Pnma, R -3c and Pm-3m respectively.
Fabrication of dye-sensitized solar cells with natural dye pigments derived from mustard green (Brassica juncea L) and turmeric (Curcuma longa L)
Authors: Yuliasari F , Nuraini U , Aeni A R , Hidayat R 
Published: October 2024

Abstract
Natural dye molecules are good alternatives for the ruthenium-based sensitizer for use in dye-sensitized solar cell (DSSC) application. In this research, we have reported the potential application of natural pigment extracts as a dye-sensitizer in DSSC. Natural dyes were extracted using simple maceration technique from natural sources such as mustard green (Brassica juncea L) and turmeric (Curcuma longa L). UV-Vis and FT-IR characterization were employed to examined the optical characteristics and identify their functional groups of the dyes, respectively. The UV-Vis characterization of mustard green dye and turmeric dye show a wide absorption in visible region. The FT-IR spectrum of mustard green dye and turmeric dye show the presence the anchoring groups. The DSSC’s performance was studied using current-voltage (I-V) measurements and electrochemical impedance spectroscopy (EIS). It was observed that the DSSC with turmeric dye shows better photovoltaic performance than DSSC with mustard green dye correlated to its longer charge carrier lifetime.
Electronic Properties of Monolayer Graphene with Doping of Nitrogen Atom: A Density Functional Theory Study
Authors: Nenohai A J W T , Santana F M , Arifin R , Asih R , Darminto  
Published: October 2024

Abstract
As a material that has been widely researched, graphene is certainly interesting because it has many unique features. In its development, graphene is very promising as an optoelectronic material. However, in theory, graphene has obstacles in its development because its band gap position is zero. With various modifications in opening the band gap so that it does not have a value of zero. In the current research, structural modifications were carried out on graphene layers by doping with a number of Nitrogen atoms. The modeling was carried out using graphene with a supercell size of 4 x 4 x 1. Our calculations are based on Density Functional Theory using the PBE – GGA function for potential exchange correlation. The result is the Fermi level shifting and emergence of magnetic moment through doping with Nitrogen atoms. The results obtained certainly open up opportunities for the development of graphene.
Effect of The Amount of 3-(trimethoxysilyl) propyl methacrylate on Improving Surface’s Adhesive Properties of Zirconia
Authors: Triastuti Warlinda Eka , Sumarno  , Suprapto  , Airlangga Bramantyo 
Published: October 2024

Abstract
The objective of this research was silanize zirconium oxide (ZrO2) nanoparticles with 3-(trimethoxysilyl) propyl methacrylate (γ -MPS). Silanization is a surface treatment process of a material using silane compounds to improve the surface adhesive and compatibility of ZrO2 with other materials or coatings and to modify its surface. The surface modification of ZrO2 by 3-(trimethoxysilyl) propyl methacrylate as coupling agents under the influence of ultrasonic waves. The silanized ZrO2 was characterized Fourier Transform Infrared Spectroscopy (FTIR) and thermogravimetric analysis (TGA). The FTIR analysis indicated the interaction of the silane compound on the ZrO2 surface, showing characteristic peaks corresponding to Zr-OH, C-H stretching, carbonyl groups, and Zr-O-Si bonds, indicating successful grafting. The FTIR spectra for the ZrO2 nanoparticles, showing peaks at 1088 cm−1 showed the formation of Zr-O-Si covalent bonds. ZrO2 nanoparticles also exhibited a characteristic peak at 400 cm−1, indicating the deformation of Zr-O-Zr bonds. C=C, and C=O peaks are observed in the range of 1632-1714 cm−1. Thermogravimetric analysis (TGA) measures showed a higher weight loss of the silanized ZrO2 when higher amounts of silane were added.
Adsorption Capacity and Efficiency of Composite Thin Sheet Made of Chitosan-Activated Carbon on The Adsorption of Methylene Blue
Authors: Widayani  , Gusnia Yessi , Viridi Sparisoma , Wungu Triati Dewi K 
Published: October 2024

Abstract
Methylene blue (MB) is a waste dye produced by textile industries. One way to reduce MB in polluting the environment is using MB adsorbent materials, such as chitosan (CS)-based composites. This research aims to investigate the adsorption capacity and efficiency of chitosan-activated carbon composites (CS-AC), which are in the form of thin sheets, on MB adsorption. The composite was made by manually mixing the chitosan and activated carbon, and then the mixture was poured into a dish and dried at around 50 °C until a dry, thin sheet was formed. The composites were prepared with varying activated carbon mass concentrations (25%, 50%, 75%, and 100% of chitosan mass). The MB adsorption measurements were carried out using UV-Vis spectroscopy. Adsorption capacity and adsorption efficiency increase with increasing activated carbon content, and the composite containing activated carbon mass 100% of chitosan mass shows the highest values, namely 11.51 mg/g and 95.93%, respectively. Furthermore, the values of adsorption capacity and adsorption efficiency are also influenced by the initial MB concentration and mass of the adsorbent. The adsorption capacity increases with increasing initial MB concentration but decreases with increasing adsorbent mass. Adsorption efficiency increases with increasing initial MB concentration and adsorbent mass.
Assessing Turbulence Model Performance in OpenFOAM for Natural Convection Simulations
Authors: Mahmudah R S N , Widiatmono R , Darmawan D , Fikri M R H , Sidek D , Hidayah A S N 
Published: October 2024

Abstract
Natural convection processes are pivotal in various engineering applications, necessitating accurate and reliable computational fluid dynamics (CFD) models for their simulation. This study evaluates the efficacy of different turbulence models implemented in OpenFOAM for a natural convection scenario, aiming to identify the most suitable model for capturing complex thermal and fluid dynamic behaviors. We compared several turbulence models, including the k − ε, k − ω, and k − ω SST, using a benchmark thermal convection case. Our methodology involved setting up the simulations to reflect realistic thermal gradients and boundary conditions, followed by a rigorous analysis of temperature distribution, vertical velocity profiles, and computational efficiency. The results indicate that the k − ω SST achieved the lowest averaged root mean square error (RMSE) values for temperature (0.076) and vertical velocity (0.03) while also requiring the fewest convergence iterations (314) compared to k − ε (411) and k − ω (1474). These findings demonstrate that the k − ω SST model is a suitable compromise between accuracy and computational cost for engineering applications. This study underscores the importance of selecting an appropriate turbulence model in OpenFOAM to enhance the accuracy of natural convection simulations, which can significantly influence design and safety considerations in engineering systems.
Low noise signal processing for electrochemical biosensor using narrow bandwidth filter
Authors: Setiadi Rahmondia N , Umar Lazuardi , Arfianti Arfianti 
Published: October 2024

Abstract
Biosensor has an important role in several domains, including medical and environmental applications. The improvement of biosensor measurement system therefore offers a better measurement quality. The objective of this work is the development of the signal processing of electrochemical biosensor for advanced analysis and use. The noise of electrochemical sensor is considered rather higher than the other sensor due to many factors such as electrode area, solution velocity, and particle size in solution, which affect adsorption-desorption process. Moreover, the sensor signal processing also makes contribution to noise level. Therefore, it must be reduced and suppressed to obtain better measurement result. In this paper, a bandwidth optimisation method is proposed and used to improve measurement quality. The system is realized with a transimpedance circuit and low-pass and high-pass filter, so that it offers low noise characteristics. The developed proposed system has provided better improvement than the standard electrochemical biosensor system. The noise of the system can be suppressed to be lower up to 14.3% of the standard transimpedance circuit. This development is promising to give better biosensor measurement.