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An analysis on the structure and mechanical properties of the electrodeposition of Ni-Si3N4 composite coatings has been carried out. The composite coatings were deposited at the Si3N4 concentration variations of 10 gr/L, 20 gr/L, and 30 gr/L. The samples were characterized by X-Ray Diffraction (XRD) and Vickers hardness test. The XRD data obtained was used to calculate the crystallite size, lattice strain, residual stress, and its relation to the mechanical properties of the coating are presented. The results showed that Ni crystal growth was resisted by increasing Si3N4 concentration due to the increase of Si3N4 crystal size followed by the decrease of lattice strain, internal stress and residual stress. From the hardness test result, it showed that the high hardness of composite at high Si3N4 concentration indicate the contribution of crystal refinement rather than coating stress. [ABSTRACT FROM AUTHOR]

Volcanic ash is danger for aviation because it harms the flight engine. This study presented the simulation of volcanic ash dispersion with the PUFF-Langarangian methods. The data was conducted from the Tangkuban Perahu volcano, which was erupted on 26 July 2019 in West Java, Indonesia. The results simulated volcanic ash dispersion based on the ash concentration and altitude at 105 minutes after the eruption. Simulation results were then compared with the satellite image of volcanic ash dispersion from The Indonesian Meteorological, Climatological, And Geophysical Agency or BMKG. With correction factor −14.75°, then the α = 0.50717°, AR = 0.99138, the simulation was fit with the satellite image. The simulation results showed that the combination of PUFF and Lagrangian methods gave a better volcanic ash dispersion map. [ABSTRACT FROM AUTHOR]

A square-wave deposition technique synthesized platinum (Pt) nanoparticles as electrocatalysts for the ethanol electrooxidation reaction. The electrodeposition was conducted in a solution with different concentrations of H2SO4 as a supporting electrolyte. Structural analysis using an X-ray diffractometer shows that a face-centered cubic of Pt nanoparticles was successfully deposited on the substrate. At a supporting electrolyte concentration of 0.5 M, the granular particles with rough surface nanoparticles were formed. The delicate spikes, which became thicker by increasing the supporting electrolyte concentration, were found to grow on the surface of the particles. The cyclic voltammogram showed that the highest anodic current from the ethanol electrooxidation reaction was obtained by Pt0.5M, which was found to exhibit a low charge transfer resistance measured by an electrochemical impedance spectroscopy technique. [ABSTRACT FROM AUTHOR]

We briefly discuss the spiral ground state in face-centered cubic (FCC) iron implementing the generalized Bloch theorem which combines a linear combination of pseudo-atomic orbital basis sets. The generalized Bloch theorem aims to make the calculation much more efficient than using the supercell method. We use a magnetic iron atom in the primitive unit cell with a magnetic moment direction of 90o as the initial ferromagnetic state. We observe the different positions of spiral ground states for several lattice constants. For small lattice constants, the low-spin states appear, while high spin states appear in higher lattice constants. This achievement means that the spiral ground state and the spin state depend on the lattice constant. [ABSTRACT FROM AUTHOR]

We briefly considered the effect of electric field on magnon dispersion in zigzag graphene nanoribbons via density functional theory. We implemented the generalized Bloch theorem combined with the constraint scheme approach to calculate the magnon energies over the first Brillouin zone. By observing the magnon dispersion, we found the small increases of spin stiffness and critical temperature up to a certain value, but then remain constant. We conclude that the magnetism in zigzag graphene nanoribbons disappears below room temperature. [ABSTRACT FROM AUTHOR]

Alfirsa Sekar Tanmala Putri 010002-3 REVIEWER Coordinator: Riser Fahdiran, M.Si (Universitas Negeri Jakarta) Members: Prof. Dr. Mangasi Alion Marpaung, M.Si Prof. Dr. Agus Setyo Budi, M.Sc Prof. Dr. Yusaku Fujii Prof. Dr. Sunaryo, M.Si Prof. Dr. Yetti Supriyati, M.Pd. 9 th National Physics Seminar Strengthening the Freedom of Learning through Innovative Physics and Physics Education Proceedings of the National Physics Seminar 2020 Jakarta, Indonesia 20 June 2020 Editors: Hadi Nasbey (hadinasbey@unj.ac.id) Riser Fahdiran (riser-fahdiran@unj.ac.id) Widyaningrum Indrasari (widyaningrum-indrasari@unj.ac.id) Esmar Budi (esmarbudi@unj.ac.id) Fauzi Bakri (fauzi-bakri@unj.ac.id) Teguh Budi Prayitno (teguh-budi@unj.ac.id) Dewi Muliyati (dmuliyati@unj.ac.id) Department of Physics Department of Physics Education Universitas Negeri Jakarta Rawamangun, East Jakarta, 13220 Indonesia The 9th National Physics Seminar 2020 AIP Conf. Proc. [Extracted from the article]

A close system consisted of 2500 agents is simulated to observe the spread of disease that can only be transmitted through contact between two agents. This agent-based model (ABM) is accompanied by a partial differential model known as the SIR (Susceptible-Infected-Recovered) model, which requires the rate of infection and rate of recovery as parameters, wherefrom these two other parameters known as basic reproduction number can be obtained. For homogeneous agents, ABM will give similar results with the SIR model, but for an inhomogeneous agents' average of ABM with the different initial condition can approximate the results of the SIR model. Besides the inhomogeneous agents, a spatial barrier that prevents agents from moving freely in the two-dimensional space can also introduce inhomogeneity in the system. Both models must have an initial infected agent or individual to begin the infection. [ABSTRACT FROM AUTHOR]

One of the interesting aspects in the interaction between two cities or among cities is the commuter, people that do commuting every day. It is similar to a sharing of the population between two areas that bind together. A covalent bond might be the analogy in the chemical world. Usually, there is one city as the center of a commuting system, where the others are considered as a satellite city. The commuters are represented as agents in the simulation, where they commute between their home and workplace. This approach is known as an agent-based model. The average movement from point i to point j in a day will be the component mij in the origin-destination matrix (ODM), which is usually obtained from survey or observation. In this work, we would like to show that using ABM the ODM can be derived. [ABSTRACT FROM AUTHOR]

A non-invasive system based on the optical scanning method can be used to measure hemoglobin blood level because hemoglobin has a characteristic of being able to absorb optimally at wavelength 660nm for oxyhemoglobin and 940nm for deoxyhemoglobin. This hemoglobin level measuring system uses the reflectance principle. The sensor probe was designed to be used on patients' fingers, so the sensor reading results were obtained for the reflection of light, which was reflected from patients' fingers. The used sensor was FD100 that could read wavelength at 350nm until 1100nm. The LEDs used were LEDs with each wavelength 600nm and 940nm. Raspberry Pi 3 microprocessor was used as the brain of this device; this microprocessor functions to regulate the light intensity, sensor reading, data processing, visualization, and data storage. The visual result of hemoglobin value (g/dl) is obtained. The equation searching was done by comparing the hemoglobin value to the High-Performance Liquid Chromatography method and sensor reading value. This equation was implemented inside the device, and the test was done to find out the accuracy of the device. Non-invasive blood hemoglobin measuring device that has been developed has an accuracy rate of 94.2% with a standard deviation of 4.7. [ABSTRACT FROM AUTHOR]

The silent tsunami that occurred on the coast of Banten and Lampung has had an impact on coastal ecosystems, coastal resources, fisheries, and socio-economics of the local community. For this reason, the assessment of tsunami losses and impacts is important as a baseline for developing post-disaster rehabilitation and reconstruction program. This research was conducted in Labuan Sub-District that has Sukamaju, Cigondang, Teluk, and Caringin Village. The result of loss assessment estimated at 32 billion Rupiahs includes ecosystems and buildings destroyed. While the losses of the fisheries sector reached 45 million to 114 billion per month, or production only reached one third compare the same month in 2018. Therefore, rehabilitation programs are intended to strengthen the capacity of tsunami-affected communities through strengthening fisheries business capacity. [ABSTRACT FROM AUTHOR]

Tangkuban Parahu is located in the north of Bandung, the capital province of West Java. Several hydrothermal manifestations, such as hot and warm springs with a temperature of 29°C-80°C, indicate that the Tangkuban Parahu has potential as a geothermal prospect. In such a case, understanding the surface and subsurface geological structures in the prospect area is needed as the first step in geothermal exploration. This study identifies geological structures based on remote sensing and gravity datasets. Structural lineaments were extracted manually using GIS software to produce fault, and fracture density (FFD) maps from the DEMNAS dataset along with IFSAR and ALOS PALSAR images. Lineament extraction was performed at eight different sun azimuth angles (hillshade) to reduce non-meaningful lines that may appear. The FFD maps show that most of the surface manifestation correlates with the high FFD zones. Gravity method is one of the first steps in geothermal exploration to provide an overview of the distribution of rocks and subsurface geological structures. Gravity data were analyzed using the parasnis method to reflect the average of rock density. The derivative technique for gravity method is common to be applied in order to delineate subsurface geological structures [1]. In this research, we used First Horizontal Derivative (FHD) and Second Vertical Derivative (SVD) to determine the presence and the type of major fault. The results of this research indicate that most of the high FFD zones are located in the peak maximum of FHD, which has SVD=0. Nevertheless, there are 3 locations of the high FFD zone that have no peak maximum FFD. Integration of this analysis mostly shows that the existence of geological structures is related to surface hydrothermal manifestations. [ABSTRACT FROM AUTHOR]

Observations that the differentiation of stem cell into other cells, e.g. bone cell, blood cell, epithelial cell, muscle cell, nervous cell, are well known. In the recent years experiment of deposition of stem cell on a surface with nanopattern has been succesfully showing the difference of produced cells. The patterns can be in the form of nanopillar, nanowells, or other form in between. The order of magnitude of the nanostructure compared to the cell size plays also importance role, in which scale that the pattern can influence the cell, e.g. internally, externally, or until the shape of the cell colony. Single cell based on granular model is simulated using molecular dynamics (MD) method, where the content of the cell is approximated using agent-based model (ABM) to assure that the cell volume is kept constant. Due to cell shape change induced by the nanopartern, interaction between cell inner particles, performed by agents, has also changed. In this article we are reporting the development stage of an in-house simulator. [ABSTRACT FROM AUTHOR]

The depletion of the fossil fuel supply, provoking a lot of research focused on alternative or renewable energies. A hybrid power plant system (a combination of wind and solar energy) as an alternative energy to Faculty of Mathematics and Natural Sciences Universitas Negeri Jakarta is developed. The advantages of a hybrid power generation system are to combine the advantages of each power source so that each one fills the weaknesses of the other under certain conditions, so that the overall system can operate more economically and more efficient. In this research, ESM50W is used as a source of solar electricity and the 24VDC generator is used as a power plant from wind turbines. The solar power plant has an optimal voltage of 17.2 volts and an optimal current of 2.91 A. Based on the results of the measurement of the efficiency of solar power plants approximately to 14.4%. The tachometer is used to measure the speed of the wind passing through the wind turbine. The cut in speed of the wind turbine used is approximately 3 m/s. The voltage generated at a speed of 3 m/s is approximately 49.3 mV with a turbine rotation speed of 17.4 rpm. [ABSTRACT FROM AUTHOR]

The practicum device of beat frequency has been developed. The device composes of the AD9833 module as an artificial sound frequency source, Arduino Uno as a control system, and application as the output's display. The module produces an adjustable frequency of sound in real-time. Then, these frequency sources are connected to an adjustable speaker stereo as the sound's output. The instrument available produces frequencies from 0.1 Hz to 2500 Hz with a stepping frequency of 0.1 Hz. Frequency calibration was carried out using a frequency audio counter in the frequency range of 300 Hz - 500 Hz. The maximum relative error of the first frequency source and the second frequency source is 0.01% and 0.008%, respectively. The beat frequency was observed using an audacity application in the 10 s and 15 s intervals. The smallest frequency that can be observed is 0.1 Hz. Validation by a media expert is carried out to determine the feasibility of the developed device. The assessment results were 95% of all aspects. [ABSTRACT FROM AUTHOR]

Soil is the most important thing required for farming activities. High-quality soil is needed for plants to grow well. Some of the parameters that indicate quality soil are the loose structure, pH 6.5-7.5, and salinity tolerance of 0-8000 µS/cm. The decline in soil quality in Indonesia due to pollution is one of the reasons that measurement soil quality device need to be developed. This study aims to characterize the soil pH sensor and conductivity sensor used in measuring soil quality parameters. The soil pH sensor is used as a pH detector, while the conductivity sensor is used as a salinity detector, as a control system the Arduino Uno is used. The results of sensor characterization show that the pH sensor has a sensitivity of -20,114 mV / pH and a maximum relative error of 2.16%, whereas, the conductivity sensor has a sensitivity of 0.0431 mVcm / µS and a maximum relative error of 6.78%. The results of measuring soil parameters of the five different soil samples, proves that the quality of the rice field's land and garden soil samples used in this research is still suitable for agricultural land. [ABSTRACT FROM AUTHOR]

We formulated some gauge transformations of the three-dimensional Gross-Pitaevskii equation coupled by a time-dependent potential. To do that, we determined explicitly all the related functions to keep the invariance of the Gross-Pitaevskii equation adopted from the gauge transformation in the classical electrodynamics. This work can be done since the present Gross-Pitaevskii equation can remain invariant after transforming the wave function through the local phase transformation. In this case, we only discussed its mathematical aspects and ignored the physical interpretation to open all the possibilities. However, we still imposed the condition that all the lengths of vectors should be real and found that only two cases can be explored since it is impossible to obtain the appropriate transformations, except we set the potential vector to be zero and the phase to be an arbitrary function of time. Thus, it may yield the different physical interpretations using this method. [ABSTRACT FROM AUTHOR]