bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimization of anaerobic filter reactor with zeolite immobilization media for dairy sludge waste treatment for biogas production
Authors: Pampang Harun , Purnomo Chandra Wahyu
Published: October 2024

Sludge from the dairy industry’s wastewater treatment contains a high organic content and a strong odor. It is proposed to treat the sludge by an anaerobic digestion process using a continuous anaerobic filter reactor (AFR) equipped with media immobilization support and a combination of ORP and pH sensors. Three immobilized media were put into different AFRs. The process took place in a cylindrical reactor with a column height of 150 cm and diameter of 63 cm with a total volume of 30 L. The total period of the anaerobic digestion process took place 17 days after the batch process. When the experiment was carried out using a flow-rate of 5 L/day, the highest sCOD removal of 90.44 % was using bioring media. Meanwhile, using flow-rate of 8L/day the highest sCOD removal up to 88.05 % was achieved by using zeolite media. The highest average methane production was obtained 8 mL/day and 24 mL/day of zeolite media by using flow-rate 5 L/day and 8 L/day respectively and reduced HRT up to 90 hours. To ensure the cellular activity on degradation of organic compounds is measured by Oxidation Reduction Potential (ORP) value. In the first stage, the ORP value is -60.23 mV to -472.82 mV for a flow-rate of 5 L/day subsequently the second stage is -471.9 mV to -477.75 mV for a flow-rate of 8 L/day. Anaerobic filter reactors using zeolite media can retain the effect of influent perturbation with a high range of alteration of sCOD and high recovery.
The effects of voltage, particle size, and temperature on bio-oil yield produced via pyrolysis of Sargassum sp
Authors: Refki Muhammad Fuad , Wintoko Joko , Widawati Teta Fathya , Nisya Alinda Fitrotun , Budiman Arief
Published: October 2024

The energy demand is increasing due to population growth and economic activities. Currently, global energy production, including in Indonesia, heavily relies on fossil fuels like petroleum, which are depleting day by day. One renewable energy form for the future is bio-oil, produced through pyrolysis using biomass as raw material. Macroalgae biomass, particularly Sargassum sp., is a sustainable and net-zero emission source for renewable energy. Pyrolysis is a promising technique to convert Sargassum sp. into high-value charcoal, gas, and bio-oil with less than 20% moisture content. Experimental research was conducted using a simple slow pyrolysis setup, using Sargassum sp. from Pantai Trenggole, Gunung Kidul. Proximate analysis showed Sargassum sp. contains ash, water, volatile matter (Vm), fixed carbon (FC), and calorific value of 15.428%, 6.032%, 40.222%, 38.318%, and 2161.758 cal/g respectively. Regarding the experiment results, the maximum bio-oil yield was obtained at 200 V with a yield of 27.289%. For the particle size variable, the maximum bio-oil yield was achieved with particles of 10-40 mesh, resulting in 27.289% yield. Regarding the temperature variable, the highest bio-oil yield was obtained at 600 °C with a yield of 29.362%.
Thermodynamic Performance Characterization of a Small-Scale Organic Rankine Cycle with 5 kW Net Power Output
Authors: Tanbar Fefria , Panuntun Rafael Pungkas , Nugraha Ariyana Dwiputra , Tambunan Handrea Bernando , Nurfanani Achmad , Digwijaya Wigas , Muflikhun Muhammad Akhsin , Khasani  , Ariyadi Hifni Mukhtar
Published: October 2024

Indonesia’s current energy landscape predominantly depends on fossil fuels and non-renewable energy sources, thereby exacerbating the issue of global warming. On the other side, geothermal utilization in the country still needs to be expanded to reduce the dependency on fossil fuels, particularly through organic Rankine cycle (ORC) systems. As an example, Ulumbu Geothermal Power Plant in Flores Island currently uses a back pressure turbine, which releases expanded steam directly into the atmosphere at 98.7°C and 0.98 bar. This paper presents a thermodynamic analysis of a small-scale Organic Rankine Cycle with 5kW Net power output based on the waste heat data of the Ulumbu Geothermal Power Plant. The study includes selecting the working fluid based on Ozone Depletion Potential (ODP) and Global Warming Potential (GWP) values, thermal efficiency, refrigerant, and steam mass flow rate calculation. Among 20 refrigerants available in Indonesia, R245fa shows promise, offering a Rankine system efficiency of 10-11%, zero ODP, a GWP of 850, and the lowest refrigerant mass flow rate. These parameters inform useful initial parameters for designing a small-scale ORC system producing 5 kW of net power, promoting cleaner and sustainable energy solutions for communities.
Microwave-assisted synthesis of silver nanoparticles using extract of unbaked cilembu sweet potato
Authors: Aliwarga Bryan S , Muhammad Khalid , Asri Lia A T W , Wibowo Arie
Published: October 2024

Silver nanoparticle (AgNP) is one of attractive nanomaterials for biomedical applications, such as electroactive scaffold, antimicrobial treatment, anticancer therapy, and wound healing. Previously, AgNP was successfully synthesized using extract of Cilembu sweet potato (CSP) only if the extract was baked in oven at 120 °C for 60 minutes, which is an energy-intensive and time-consuming process. In this study, AgNPs was fabricated using unbaked extract of CSP with employing fast microwave heating instead of baking process. Microwave irradiation time were varied (0, 30, 60 and 90 seconds) to know the influence of microwave irradiation time on particles size and morphology of the obtained AgNPs. The obtained samples were evaluated using UV-Visible spectroscopy, dynamic light scattering and transmission electron microscopy to know the surface plasmon resonance characteristic, average particles size and morphologies of the obtained AgNPs respectively.
Fabrication and Evaluation of an Electromagnetic Shielding Material Made of Randomly Chopped Tape Carbon Fiber/Polyamide 6 Composites
Authors: Aripin A B , Sasongko N A , Purqon A , Hayakawa K
Published: October 2024

Environmental pollution generated by electromagnetic wave radiation has significantly increased including in automotive applications. Thus, material technology, including polymer composite, has attracted a reduction of the negative effect of electromagnetic radiation. In this study, carbon fiber reinforced polyamide thermoplastic (PA-6/CF) made of carbon fiber with polyamide 6 tape, in the shape of a half-box, was produced using the hot compression method with different tape-length, and then the electrical conductivity and electromagnetic shielding performance were evaluated. The electrical conductivity was obtained from the resistivity measured by using a digital multimeter. Whilst the effectiveness of electromagnetic interference shielding (EMI-SE) was investigated using two methods, calculation, and actual measurement. The result shows that there is a different electrical conductivity between base and slope area of the PA-6/CF box composite. It also was observed that the actual EMI shielding performance shows a corresponding increase with the length of chopped carbon fiber tape and has a higher value compared to the calculated EMI-SE. Then, the highest value obtained for actual EMI-SE was 54 dB for the PA6/CF composite with 20-mm tape length, in the frequency range 0.3 – 1 GHz, and on horizontal antenna polarization. Whereas the composite with 10-mm and 15-mm tape length was the lowest EMI- SE (38 dB) on vertical antenna polarization, in the same frequency range. Furthermore, the microscopy analysis depicted that there are more voids exist in the slope area compared with the base area of the PA-6/CF composites. Finally, the molded PA-6/CF composites can be used as the battery enclosures of electrical vehicles in automobiles.
Influence of Sulfur Addition on The Physical and Photocatalytic Properties Biosynthesized Se-doped ZnO Nanoparticles
Authors: Rini A S , Sitorus A H , Rati Y , Simatupang M P , Taer E , Usman Z , Jasril
Published: October 2024

The objective of this study was to investigate the influence of Sulfur (S) addition to selenium-doped zinc oxide (Se-ZnO) nanoparticles on their physical properties and photocatalytic activity. S,Se-ZnO sample was prepared by adding 1wt% sulfur onto 4%Se-ZnO nanoparticles. In the synthesis procedure, microwave irradiation was used as heating power and matoa leaf extract was used as a bioreductor. The nanoparticles were characterized using UV-Vis Spectroscopy, X-ray diffraction (XRD), and Field Emission Scanning Electron Microscopy (FESEM). The calculated band gap energies of Se-ZnO and 1% S,Se-ZnO are 2.38 eV and 2.62 eV, respectively. Both samples exhibit a hexagonal wurtzite structure. FESEM image of addition S reveals flower petal flake formations and decrease particle size of 187 nm. The photocatalytic activity of nanoparticles was evaluated through 4-nitrophenol (4-NP) degradation under UV-C irradiation. 1% S,Se-ZnO exhibits high photocatalytic efficiency compared to Se-ZnO, with a degradation percentage of 85.09% after 60 min and a reaction rate of -0.0315 min−1. Based on these results, the addition of S on Se-ZnO biosynthesized shows improve physical properties and efficient photocatalytic materials for pollutant removal.
Examination of the Effectiveness of Orange Peel Pectin and Chitosan as Edible Coating Materials for Tomato Fruit (Lycopersicum esculentum Mill.)
Authors: Sembiring Emita Br. , Frida Erna , Sitorus Zuriah , Sembiring Timbangan
Published: October 2024

This study investigates the effects of varying pectin concentrations in edible coatings on tomatoes, focusing on viscosity, surface morphology, weight loss, and structural analysis. The viscosity of pectin-based solutions increased with higher concentrations, ranging from 451.5 cP for 1.0 g to 535.2 cP for 2.5 g of pectin. A coating with 2 wt.% pectin and chitosan showed a uniform dispersion of curcumin nanoparticles and maintained a compact structure, while higher concentrations led to increased porosity and roughness. The coating significantly reduced weight loss, with only a 7.3% reduction after 21 days in the 2 wt.% pectin sample, compared to 10.95% in untreated tomatoes. FTIR analysis revealed functional groups that enhance the coating’s stability and barrier properties. The results indicate that optimizing pectin concentration is key to achieving a balance between coating effectiveness and ease of application, ultimately extending the shelf life of tomatoes.
Characterization of Adsorbents Based on Pahae Natural Zeolite and Candlenut Shell Activated Carbon for Peat Water Purification
Authors: Susilawati  , Frida E , Andriayani  , Sinuhaji P , Sebayang P , Padang S T , Irma M
Published: October 2024

The importance of developing effective adsorbents for environmental applications cannot be overstated, particularly in the context of water and wastewater treatment. Previous research has extensively explored various natural and synthetic materials for their adsorption capabilities. Pahae natural zeolite, a naturally occurring aluminosilicate mineral, is known for its excellent ion-exchange properties and high surface area, making it a promising candidate for pollutant removal. Similarly, activated carbon derived from agricultural by-products, such as candlenut shells, has been recognized for its superior adsorption characteristics due to its porous structure and large surface area. This study focuses on the synthesis and characterization of an innovative adsorbent combining Pahae natural zeolite and candlenut shell activated carbon. The goal is to harness the synergistic effects of both materials to enhance the adsorbent’s performance. By investigating various compositions of these two materials, the research aims to optimize the adsorbent’s physical properties, particularly porosity and water absorption capacity. The findings reveal that a composition of 75% Pahae natural zeolite and 25% candlenut shell activated carbon yields optimal results, with a porosity of 57.26% and a water absorption capacity of 56.70%. These results underscore the potential of this composite adsorbent in improving water treatment processes and contribute to the growing body of knowledge on sustainable and efficient adsorbent materials.
Differences Photopolymerizations and Characterizations of Monomers Liquid Crystal between Mesogen Reactive RM 257 and Cholesteryl Acrylate using method of UV Curing
Authors: Afrizal  , Budi Setia , Riswoko Asep , Lestari Fuji , Ningsih Selvia
Published: October 2024

Mesogen reactive RM257 and cholesteryl acrylate are two types of liquid crystal with the characteristic property of possesing polymerizable groups. Cholesteryl acrylate has interesting properties that can form a helical spiral structure. Previous research in maintaining the helical structure has not been maximized. In this study, we will explain how the UV curing process is a way to fix the helical structure. Monomer phase of cholesteryl acrylate only appears at mesophase temperature, in order to maintain the helical structure of the cholesterl acrylic compound is polymerized. Mesogen reactive RM257 is monomer liquid crystal that acrylate functions as back bone polymer chain. Cholesteryl acrylate and RM257 each monomers is polymerized using UV light with 55 watt of wavelength which has 365 nm. The polymerization process produces a new functional group formed by C-O esters at wave numbers 1047 cm−1 and 1055 cm−1. XRD diffraction pattern showed peaks at 2θ in 7.5°,15°, and 20°. Photo SEM image showed crosslinked morphology structure. Based on the results of this study, it is hoped that the polymer RM257 and acrylate coliform can be smart materials for sensor applications and further technological material composites.
Incorporation of Gold Nanoparticle into ZnO Electron Transport Layer to Improve Performance of Hybrid Bulk Heterojunction Solar Cell
Authors: Merdeka Muhammad Cikal , Syarif Nur Fadhilah , Hidayat Rahmat , Wulandari Priastuti
Published: October 2024

We have investigated the effect of localized surface plasmon resonance (LSPR) from gold nanoparticles incorporated into the electron transport layer (ETL) of zinc oxide (ZnO) on charge carrier transport in order to improve the performance of inverted hybrid bulk-heterojunction solar cells. Synthesis of gold nanoparticles capped by 3-mercaptopropionic acid (AuMPA) and oleylamine (AuOA) was carried out by use of the reduction method and the fabrication of solar cell device with the configuration of ITO/ZnO:AuNPs/P3HT:PCBM/PEDOT:PSS/Ag was done by spin coating and thermal evaporation techniques. The absorbance spectra show a plasmonic peak of AuMPA in solution at 521 nm, while AuOA has a plasmonic peak at 531 nm, with both solutions showing a red-wine color. In our investigation, the incorporation of AuMPA about 2.65wt% or AuOA about 3.5 wt% in the ZnAc solution is quite stable. With the addition of 1.77 wt% AuMPA, the fabricated devices show a significant improvement at short circuit condition (JSC) from 46.67 mA/cm2 to 83.11 mA/cm2, resulting in an increase in power conversion efficiency (PCE) from 5.64% to 9.00% under the illumination of 100 mW/cm2 simulated solar irradiation. While the AuOA addition of 2.65 wt%, the JSC increased from 22.67 mA/cm2 to 44.12 mA/cm2 along with an improvement of PCE from 2.71% to 5.32%. The experiment results suggest that the electron mobility or charge carrier transport to the indium tin oxide (ITO) cathode is improved by the local electric field enhancement around the zinc oxide (ZnO) electron transport layer due to the effect of gold nanoparticles (AuNPs).
Effect of Atomic Vacancy Defect in h – BN Monolayer on Electronic Properties: A DFT Study
Authors: Nenohai A J W T , Santana F M , Arifin R , Asih R , Darminto
Published: October 2024

h-BN is a 2D material which also has considerable development potential in several fields. 2D materials such as h-BN are basically insulating materials but have unique properties and it would be good if they could be developed, especially to meet future energy needs or in the development of electronic devices. Therefore, the properties of h-BN are certainly needed to support this, one of which is the magnetic properties of h-BN. In this research, we modified the h-BN structure by providing defects in the form of vacancy defects by removing atoms in the h-BN layer. We modeled a monolayer h-BN with a supercell size of 4 x 4 x 1, and our calculations were carried out with Quantum ESPRESSO, which is based on density functional theory. The results we obtained showed the emergence of magnetic moment values in h-BN due to defects in the form of atomic vacancies. Furthermore, this research successfully illustrates how vacancy defects in h-BN can modify the band structure, leading to changes in electron behavior around the Fermi energy level.
The Effect of Quenching Process on The Microstructure and Hardness of AISI 4140 Steel
Authors: Basori I , Masitah I , Susetyo F B , Nanto D
Published: October 2024

Steel is a metal that has good strength widely used in industry, both in the construction and automotive fields as a protective material applied to the body of combat vehicles. Combat vehicle body materials must have high strength and hardness to withstand bullet penetration. Meanwhile, some types of steel do not have such strong point to endure impact and bullet penetration, so their strength and hardness need to be increased. One method that can be used to increase the qualities of steel is heat treatment, such as quenching process. In this research, the quenching process was carried out on commercial AISI 4140 steel to increase its hardness. The heat treatment process for AISI 4140 steel begins with an austenization process at a temperature of 850 °C with varying holding times, followed by a quenching stage using SAE 40 oil media. Afterward, the microstructure observation and hardness testing of the test material were carried out using the Optical microscope and Vickers method. The raw material has a hardness value of 215.58 VHN. After the heat treatment process in 30, 60, and 90 minutes was carried out, the hardness value of AISI 4140 steel reached 371.24, 474.48, and 545.5 VHN, respectively. The research results show that the longer the holding time in the quenching process lasts, the more increases the hardness value of the steel will be, which result in microstructure as a dominant martensite phase.
Stimulated Brillouin Scattering Gain of Waveguides Calculated with Acoustic Perturbation Method
Authors: Ramadhan K , Permana D P , Hidayat W , Soehianie A , Marpaung D , Iskandar A A
Published: October 2024

Stimulated Brillouin Scattering (SBS) is a phenomenon of energy transfer from an optical pump beam to longer wavelengths of light through its interaction with the medium via acoustic phonons. Previous studies have reported a calculation of the SBS gain based on the optical force approach, where the gain is not only affected by the classical paradigm of intrinsic material’s nonlinear effects in the form of electrostriction but also due to radiation pressure. In this work, the acoustic perturbation approach is applied in analyzing the optical and mechanical response of the waveguide, wherein calculating the scattering process, the changes of the waveguide structure due to photoelasticity (PE), termed Moving Boundary (MB), are considered. This acoustic perturbation method avoids uncertainties related to optical force contributions. To validate its applicability, the present method is used to calculate the SBS gain of various waveguide structures, namely an unsuspended Silicon nano-waveguide, ridge Lithium Niobate (LiNBO3) nano-waveguide on Sapphire (Al2O3) substrate and buried Arsenic trisulfide (As2S3) in Silicon dioxide (SiO2). The forward and backward SBS gain obtained using the present method of acoustic perturbation are similar to the reported values obtained from other methods of calculation as well as experiments.
Preparation of hydrilla verticillata activated carbon adsorbent for remediation of wastewater containing the active metal chromium
Authors: Tarigan Enda Rasilta , Frida Erna , Humaidi Syahrul , Susilawati
Published: October 2024

This research aims to determine the capacity of Hydrilla Verticillata activated carbon adsorbent in absorbing the heavy metal chromium. The method used in making Hydrilla Verticillata activated carbon is by carbonization at a temperature of 3000C and chemically activated. Activated carbon was contacted with a solution of the heavy metal chromium with a concentration of 100 ppm with contact times of 15, 30, 45, 60, 90 and 120 minutes. The structure of hydrilla verticillata active carbon from the XRD results is graphite and BET BJH characterization data shows that activated carbon has a surface area of 53.143 m2/g, an average pore size of 0.2764 nm and a pore volume of 0.0789 cc/g. The SEM- Edx characterization results show that the size distribution is not homogeneous but forms agglomerations like plate particles consisting of slitted pores. Test results using AAS show that the ability of hydrilla verticillata activated carbon to remediate the heavy metal chromium based on contact time is around 47.35%, 46.77%, 49.08%, 54.85%, 61.30% and 69.69% and the adsorption capacity is around 13.94 mg/g.
The Correlation Between Compressive Strength and The Size of Pore Fly Ash and Perlite Concrete Geopolymer at High Temperature
Authors: Farida F M , Kusumohadi C S , Alanas E , Fikri M F
Published: October 2024

Burned material experiences a decrease in yield strength and elasticity modulus. Fire supervision is required. One of the sustainable material is geopolymer. In this study, fly ash and perlite-based concrete geopolymer have been burned for 900°C for 2 hours. It is followed by Surface Area Analyzer test equipment. The size of pore changes for burned concrete geopolymer. Meanwhile, one of the strength of concrete geopolymer indicator is compressive strength. Both of the results of compressive strength and the pore size are conducted through experimental study. Bet method has been used to measure pore size of it. UTM machine has been used to calculate compressive strength. The surface area analyzer test results show that the addition of perlite to fly ash-based geopolymer concrete will decrease the value of surface area, pore volume, and pore distribution in burned geopolymer concrete, but the addition of perlite to fly ash-based geopolymer concrete will increase the value of pore distribution and decrease the value of surface area and pore volume in unburned geopolymer concrete.
Design of Biomaterial Absorber using coconut shell charcoal for 38 GHz frequency
Authors: Umaisaroh Umaisaroh , Alaydrus Mudrik , Handoko Erfan , Alferinanda Nadio
Published: October 2024

Activated carbon derived from coconut shells has gained significant attention as an effective and sustainable absorber material. The process involves carbonizing coconut shells to create a carbon-rich base, followed by activation through heat and steam, leading to a porous structure with a vast surface area. In this research, coconut shell charcoal is used to make an absorber for microwave application. We used relative permittivity (ε) 3.178, relative permeability, (µ) 1.215 and dielectric loss tangent (σ) 0.0719 to simulate the material based of coconut shell charcoal. We investigate the absorption in terms of design and the size of the proposed absorber in the frequency region of 26.5 GHz to 40 GHz (Ka band). The optimal absorption was achieved with a transmission factor of -29.22 dB and -52.94 dB in both simulation and measurement. The absorption percentage > 99 % for the flat design of the coconut shell charcoal design with the thickness of 16.9 mm.
Fuzzy Logic-Based Feedwater Controller for the Super Fast Reactor
Authors: Sutanto  , Santi Marili , Lestari Anggun Dwi
Published: October 2024

Super fast reactor is a Generation IV reactor with water coolant at supercritical pressure. It has advantages of having high efficiency of about 44%, more economical and excellent safety features. Its last core design which adopted one heating in one coolant cycle, however, results a large density change along the fuel channels. It leads to a sensitive steam temperature change against a change of power which might mismatch with the flow change. The sensitivity should be reduced to maintain the structure integrity of the reactor components. A feedwater controller which based on fuzzy logic was used to reduce the sensitivity. Method of fuzzy-based control is applied. Two signals of the temperature and the power changes were taken as the inputs of the fuzzy controller, and change of the feedwater coolant flow was taken as the control output. Fuzzifications used triangular member functions with Tsukamoto fuzzy model for inferencing process. Two control parameters of member function spread and signal values which lead to fuzzy degree of 1 were optimized so that the criteria of outlet coolant temperature and the stability were fulfilled. Test results of the control system showed that the deviation of the water temperature at outlet side could be kept within the criteria when mismatch change of power and water flow happened. The temperature deviation could be supressed by using the fuzzy-based control.
Calculation on power factor and figure of merit in a single-layer NiBr2
Authors: Prayitno T B , Hakim D F , Jonuarti R
Published: October 2024

Implementation of the classical Boltzmann transport theory has been performed to calculate the power factor, as well as the figure of merit in a single-layer NiBr2 after performing density functional theory. Those two properties were formulated from the Seebeck coefficient, electron thermal conductivity, and electrical conductivity. An in-plane ferromagnetic formation of magnetic moments in the Ni atoms was applied in the primitive cell. We found a small power factor, but a high figure of merit at the Fermi level near critical temperature. Since the efficiency of thermoelectric materials is represented by the figure of merit, a single-layer NiBr2 is a strong candidate for thermoelectric materials which can be applied in future devices.
Navigating Urban Skies: Obstacle Avoidance Strategies for Quadrotor MAVs
Authors: Pebrianti Dwi , Kee Wong Jack , Bayuaji Luhur , Solichin Achmad
Published: October 2024

Micro Aerial Vehicles (MAVs) has gained attentions since more than two decades ago starting from the applications in air combat up to civil applications such as packet deliveries, environmental monitoring, and surveillance. In an environment such as cities that grows denser, navigation and control for drones becomes challenging to ensure safe navigation around buildings and other obstacles. This study proposes an approach for obstacle avoidance for MAVs by using ultrasonic sensors. Four sensors are strategically positioned to cover the front, right, back, and left directions. Additionally, a downward-facing sensor measures the quadrotor’s height above ground. Our goal is to develop autonomous MAV that can avoid obstacles, ensuring safe flight even in complex urban landscapes. The scenario implemented in the study is by introducing obstacle in any directions. When an obstacle is detected by the ultrasonic sensor, the signal will be sent to microcontroller and the attitude of the MAVs, roll or pitch will be adjusted to avoid the obstacle by moving to the counter direction of the obstacle. We conducted 20 trials of experiments by varying the gain values of Proportional Integral Derivative (PID) values, we fine-tune our obstacle avoidance algorithm. Modifications include optimizing roll and pitch adjustments, refining detection height thresholds, and implementing countermeasures after obstacle clearance. The results show that our proposed method has 10% overshoot when detecting any obstacles in different directions to avoid the obstacles. Our findings contribute to the advancement of safe and efficient urban drone operations, bridging the gap between technology and real-world challenges.
Simulating 2D Fluid Motion with the Smooth Particle Hydrodynamic Approach
Authors: Nooreza K , Wungu T D K , Sobar F T A
Published: October 2024

Virtual two-dimensional (2D) fluid simulation is useful for directly simulating fluids in various situations, including geological simulations for landslides and fluid simulations for teaching. This research aims to simulate the behaviour of three different types of fluids (water, coconut oil, and glycerine) in a 2D container and analyse how these three types of fluids behave under various conditions, including interactions with boundaries. The research used Python programming to simulate fluids and the Wondershare Filmora X application to combine images. The Smooth Particle Hydrodynamics method simulated fluid in a 2D container with 10,000 particles by deriving the force density field directly from the Navier-Stokes equations. The Navier-Stokes equations were utilized to find the acceleration and velocity of fluid particles by considering external forces, internal forces, and gravity through this method. Acceleration and velocity were validated due to wall collisions, collisions with boundaries, and collisions between particles, which caused changes in particle position and velocity. During visualization, the fluid velocity decreased over time due to attenuation caused by interactions between neighbour particles, particles with boundaries, and particles with walls. From the simulation, it was observed that the fluid flowed from a higher place to a lower place, with fluid particles taking the shape of the container and the surface of the fluid forming waves. On the other hand, simulations with boundaries indicated that smaller gap sizes and higher viscosities led to increased difficulty in fluid penetration into the gap within the container.
LSPR Sensitivity of Ag-X NRs Core-Shell (X=Au, Al, TiO2, ZnO, SiO2): A Boundary Element Method Simulation Study
Authors: Azmi D U , Yudasari N , Putri K Y , Djuhana D
Published: October 2024

Silver nanorods (Ag NRs) have garnered significant attention in sensor applications due to their exceptional sensitivity to localized surface plasmon resonance (LSPR), facilitating the detection of minute changes in the surrounding environment. However, the inherent instability of silver in various environmental conditions poses a considerable challenge to the long-term reliability and reproducibility of Ag NR-based sensors. Core-shell structure Ag NRs by coating with Au, Al, TiO2, ZnO, and SiO2 layers reduce instability. These coatings act as protective barriers, shielding the underlying Ag NRs from environmental factors while preserving their LSPR properties. In this study, we employ the Boundary Element Method (BEM) simulation to investigate the sensitivity of coating Ag NRs with different materials (Au, Al, TiO2, ZnO, and SiO2) in enhancing both their stability and sensitivity for LSPR-based sensing applications.
The Development of Remotely Operated Underwater Vehicle for Plastic Waste Detection with Raspberry Pi
Authors: Delina M , Taryudi  , Amin M F , Hussaan A M , Trismidianto  , Arifin F I , Syah S M I
Published: October 2024

Underwater Plastic waste has had a serious impact on the environment. Unfortunately, Detecting and collecting underwater plastic waste is still a challenge, especially in Indonesia because of its position in the water, and the water turbidity. In previous research, a computer algorithm for detecting underwater plastic waste has been developed with Yolov3. To improve the research, we developed a Remotely Operated Underwater Vehicle (ROUV) with Raspberry Pi through the Research and Development (R&D) method. This ROUV is like a submarine that operates in the water and is integrated with a camera and computer algorithm to detect plastic waste. To get close to the real condition, we created an artificial water environment in a pond with various turbidity (from 20 to 200 Nephelometric Turbidity Unit). We use 30 pieces of plastic waste in several colors: white, red, black, and transparent. The plastic waste dipped in the water and was then detected by the ROUV camera. The result shows that the effective threshold for object detection is around 100 Nephelometric Turbidity Unit (NTU). Below 100 NTU, although the number of detected plastic images decreases as the turbidity increases, the visibility and contrast still allow for reasonably good object detection. The average confidence value for detection at turbidity levels below 100 NTU is 77%. At high turbidity conditions, the detection model may require adjustment or retraining with data that reflects those turbidity conditions.
Enhancing Seismic Data Accuracy: An Advanced Health Diagnosis Method for Seismometers Performance Evaluation
Authors: Annisa Risa , Jannah Miftahul , Saputro Adhi Harmoko , Lestari Titik
Published: October 2024

Seismometers play a crucial role in monitoring seismic activities, yet their performance can degrade over time due to environmental conditions, aging components, and external disturbances. This study introduces an innovative seismometer health diagnosis method based on seismic signal analysis tailored for the Indonesian earthquake station network. The proposed method involves trim signal, signal resampling, filtering, and deconvolution of instrument response to process seismic data from the earthquake station network in Indonesia, specifically from Honshu, Japan 2024 of seismic events in the regions of Java, Indonesia, using Python software. By understanding the condition of the seismometer, the accuracy of data can be optimized or improved, damage can be minimized, and maintenance costs can be reduced. Seismometer health diagnoses are conducted using cross-correlation analysis and amplitude ratios of seismic signals from 3 neighbour seismic stations using 88 stations to diagnosis, we found that 90% of the seismometers in the Java, Indonesia region are still health condition and 10% of the seismometers are unhealth condition. The health parameters could be used to diagnose seismometer performance in the Indonesian earthquake station network.
Automated Classification of Egg Freshness Using Acoustic Signals and Convolutional Neural Networks
Authors: Iswanto B H , Putri D S D
Published: October 2024

The acoustic response of eggs has not been fully optimized for quality detection purposes. This research investigates the utilization of acoustic response as input features for classifying fresh and rotten eggs using Convolutional Neural Networks (CNN). Acoustic measurements were conducted using an experimental setup involving a striking rod, microphone, and microcontroller to capture acoustic responses from eggs struck vertically and horizontally. Features such as energy, entropy, zero crossing rate, spectral centroid, and Mel Frequency Cepstral Coefficients (MFCC) were extracted from the recorded acoustic signals. The study utilized a sample set of 200 intact chicken eggs without cracks, equally split between fresh and rotten eggs. Principal Component Analysis (PCA) revealed significant differences in acoustic responses between fresh and rotten eggs, with clear separation observed in horizontal measurements. Three primary classification models—Convolutional Neural Network (CNN), Deep Neural Network (DNN), and Support Vector Machines (SVM)—were evaluated for this classification task. In vertical tapping, CNN and DNN demonstrated stable performance with approximately 85% accuracy, while SVM slightly trailed with around 80% accuracy. However, in horizontal tapping, all three models achieved perfect classification with accuracy, precision, recall, and F1-score reaching 100%. This study demonstrates the effective use of acoustic response as input for Deep Learning models to distinguish between fresh and rotten eggs. The findings highlight the potential application of this technology in the food industry to ensure product quality before consumption, with significant implications for developing reliable automated solutions. Future research could expand validation using larger datasets and optimize sensor usage and data processing techniques to enhance detection consistency and reliability.
Automated Digital Sfigmomanometer Prototype Testing
Authors: Umiatin U , Ciptarisa A , Ifa R P N , Abidin M
Published: October 2024

Blood pressure is the pressure of blood flow in the arteries generated by the heart. Abnormal blood pressure can lead to hypertension and hypotension. Hypotension, or low blood pressure, has a prevalence of 5% to 34% among individuals aged 17 to 19, and over 50% in the elderly. Hypertension can cause death in patients with heart disease. About 39.7% of people suffer from hypertension, especially those over the age of 60. Blood pressure measurement needs to be done regularly because it has impact such as early detection of blood pressure health conditions and monitoring of health conditions for those already diagnosed with abnormal blood pressure. Unfortunately, only 59% of the population in Indonesia regularly measure their blood pressure. Accurate blood pressure measurement can be performed using an invasive method. Another method is non-invasive, which can be done using a sphygmomanometer that applies the oscillometric method. This method uses pressure oscillations in the cuff influenced by the pulse in the blood vessels. When using this method, several factors need to be considered, such as body position, cuff size, and the technique used during the measurement. In this study, a fully automatic digital sphygmomanometer has been developed with a cuff attached to the device, equipped with a thermal printer to print out the measurement results and classify blood pressure categories. The advantage of the developed prototype is that it has a smaller relative error value, with 1.03% for systolic blood pressure and 1.45% for diastolic blood pressure, and has already been integrated with a thermal printer to directly print the measurement results.
Design a Simple Portable Electrocardiograph Based on the IOT Concept
Authors: Syam Rafiuddin , Djatmiko Wisnu , Yusro Muhammad , Oktaviani Vina , Aeni Siti Nur , Mochtar Andi Amijoyo
Published: October 2024

There are many cases of heart disease with death associated. The symptoms are not always clearly visible and require examination using an electrocardiogram (ECG) device to be detected. Recording human electrical activity can be done in various organs of the human body, one of which is in the heart. An ECG is a medical test to detect electrical activity signals produced by the heart by exchanging the signals on a monitor or graph on paper. This study aimed to design, build, test, and analyze a portable ECG device that is compact and easy to use. This portable electrocardiogram helps monitor human heart rate to check heart rate periodically. Tool design is done by making tools equipped with a monitoring system. The proposed system uses the AD8232 sensor to detect a person’s cardiac activity. Arduino Nano is a microcontroller connected to ESP32 with a WiFi feature. Heart activity monitors can be done anywhere by applying the Internet of Things concept, namely with the Ubidots application. A portable tool using Li-Ion batteries as a tool voltage source and BMS 3S as a charger, this tool is also equipped with a 3.2-inch TFT screen as a graph viewer of the results of monitoring heart activity. The results showed that the system could monitor the user’s heart for 5 minutes when sitting, walking, and running. The system created has been able to send heart signal data to be processed by Arduino Nano and ESP32 as a data transfer tool so that the data generated in the form of electrocardiogram graphs can be displayed on the Ubidots application. TFT LCDs can display electrocardiogram graphs generated by the electrical activity of the human heart and beats per minute values. The AD8232 sensor can measure beat per minute (bpm) values with an average increase in bpm values for walking conditions of 17% and running conditions of 19.17%. The AD8232 Sensor Performance can detect the user’s heart rate with a percentage of data difference between walking and running conditions of 2.88% with an accuracy rate of 97.12%.
Exomod: A Python Library for Exoplanet Transit Light Curve Fitting and Stacking with Background Simulation and Optimization
Authors: Akilah Rafa Nanda , Randolph Bryant , Khawariz Andaristiyan M.
Published: October 2024

From the light curve taken during exoplanet transit, important parameters such as the radius ratio of the star-planet, impact parameter, inclination, and relative tangential velocity could be derived. A module was developed in the form of a Python library based on modeling using background simulation and fitting by utilizing global and local optimization, such as differential evolution and the Broyden–Fletcher–Goldfarb–Shanno (BFGS) method. For more accurate fitting, the effects of linear limb darkening on exoplanets are also included. The performance testing for the program was done by using dummy data to test its accuracy, followed by validation tests using WASP-12b transit curves to find out any discrepancies between our model and real exoplanet data. While performing a characterization test on WASP-12b, we found an interesting result regarding its impact parameter and the exoplanet’s velocity, which might be an interesting subject for further analysis.
2D Magnetotelluric Resistivity Structure Modeling Using Finite Element Method Based on Vector Triangular Grid and Its Application to Lembang Fault MT Data
Authors: Naufal Muhammad Risyad , Nurhasan Nurhasan
Published: October 2024

Magnetotellurics is one of the geophysical exploration techniques that relies on the natural fluctuations of electromagnetic waves to delineate their influence on the Earth. The primary focus of this method is to reveal the structure of Earth’s subsurface with the value of resistivity. The application of numerical approaches in magnetotelluric modeling has proven to be an efficient method in various theoretical studies in the field of geophysics, particularly in the context of modeling two-dimensional structures. This research explains a 2D resistivity structure modeling using a vector finite element method. This approach utilizes the edges of elements as vector bases. The presented results include response values such as apparent resistivity and impedance phase at the surface. The study employs the standard model from COMMEMI as a reference to validate the modeling program. Furthermore, the results from this modeling program are compared with the outcomes of the modeling program developed by Weaver et al. The good results were obtained with error values for each model for layered and homogeneous Earth < 3%. Additionally, for the reference model COMMEMI, errors of 3.4393% and 1.4050% were obtained for TE and TM modes, respectively. Furthermore, apparent resistivity and impedance phase results closely approximated the reference values for the topography model. Subsequently, in the application to field data, specifically the Lembang Fault, errors were obtained for the TE and TM modes within the range of 1.16 – 9.16% for each MT data acquisition site.
Madden Julian Oscillation Influence on Diurnal Variation of Rainfall in Mentawai Islands Indonesia from IMERG Observations
Authors: Erajalita A , Marzuki M , Vonnisa M , Ramadhan R , Yusnaini H , Sari A Y
Published: October 2024

Mentawai is a small island located in the Indian Ocean, so its rainfall pattern tends to be different from the larger islands in Indonesian region. Various scales of factors influence this, one of which is Madden Julian Oscillation (MJO). The aim of this study is to determine effect of MJO in Mentawai Islands on the diurnal variation of rainfall. Rainfall data was collected from 2000-2022 from Integrated Multi-SatellitE Retrievals for GPM (IMERG). Diurnal variations were observed in the accumulation (PA), frequency (PF), and intensity (PI) of rainfall and MJO was classified into active phase (2, 3, 4, and 5) and inactive phase (1, 6, 7, and 8) during the seasonal period (DJF-MAM-JJA-SON). Diurnal peak times in PA, PF, and PI occur later when MJO is active than when MJO is inactive, especially in JJA and SON periods in Mentawai Islands and Mentawai Strait. When MJO is active, average PA and PF are higher than when MJO is inactive. The average of PI is higher around the ocean during active and inactive phases of MJO. The number of short-duration rainfall events occurred over the land, while long-duration rainfall occurred over the ocean.
Comparison of Climatology of Precipitation Diurnal Cycle in Kalimantan Deduced from Rain Gauge and IMERG Data
Authors: Sari A Y , Marzuki M , Vonnisa M , Ramadhan R , Yusnaini H , Muharsyah R , Erajalita A
Published: October 2024

The diurnal cycle is repetitive pattern of changes in weather factors on land and oceans due to the Earth rotation. Kalimantan Island as the largest island in the Maritime Islands region has a complex rainfall pattern that is influenced by local factors and global circulation. The research was conducted to find out the climatological comparison of the diurnal cycle of rain in Kalimantan based on rain gauge data and Integrated Multi-SatellitE Retrievals for GPM Version 07 (IMERG V07) data for the period 2016 - 2022. Data validation using rain gauge data to validate and calibrate IMERG satellite data, improving the accuracy and reliability of satellite rainfall estimates. The diurnal cycle is evaluated through a Precipitation Amount (PA), Precipitation Frequency (PF), and Precipitation Intensity (PI) every hour. The results show that the maximum rainfall occurs in the afternoon and evening along the coast, and in the middle of the night and morning on the Kalimantan plains. Kalimantan has high rainfall intensity values at short rainfall durations, i.e. rain lasting less than 3 hours. This is expected to improve the quality of hydrometeorological disaster mitigation in Kalimantan.
Multivariate Analysis of Geochemical Data to Determine Critical Minerals in Prigi Beach Sand, Trenggalek
Authors: Maulida S , Zulaikah S , Hapsoro C A , Hariyanto Y , Zakly H I , Muztaza N M , Suaidi D A , Pratama A
Published: October 2024

Critical minerals are essential elements mainly for industry. As technological advancements, the demand for critical minerals also increases. Critical minerals include Rare Earth Elements (REE), Lithium (Li), Gallium (Ga), Germanium (Ge), Platinum Group Metals (PGM), Indium (In), Beryllium (Be), Tungsten (W), Cobalt (Co), Molybdenum (Mo), Niobium (Nb), Antimony (Sb), Vanadium (V), Nickel (Ni), Chromium (Cr), Tellurium (Te), Tin (Sn), Thorium (Th), Zirconium (Zr), Hafnium (Hf), Selenium (Se), Rhenium (Re), Phosphate (P), Potassium (K), and others. This study aims is to figure out the distribution of critical minerals in the sand of Prigi Beach, Trenggalek. Chemical elements are determined using X-Ray Fluorescence (XRF). Based on data analysis, critical minerals were detected with the presence of elements such as Al, K, Ca, Si, Ti, P, V, Mn, Cr, Zn, Fe, Sr, Eu, and Cu. Using the Pearson Correlation and Principal Component Analysis (PCA) methods. Significant correlations were found between (Al-Zn), (Si with K-Ti-V-Fe-Cu-Eu), (K with Ti-V-Fe-Cu-Eu), (Ca-Sr), (Ti with V-Mn-Fe-Cu-Eu), (V with Fe-Cu-Eu), (Fe-Eu), and (Cu-Eu). The elements that dominate the critical minerals based on geochemical data analysis of the sand revealed three highest concentrations consisting of Fe (41.44%), Si (35.32%), and Ca (10.96%). Base on several previous studies on critical minerals in beach sands, including a study by Endang (2023) it is know that Fe is a dominant element compared to others such Ca, Al, and K. This is due to the influence of various geological conditions and human activities.