Modified Spin Coating Method for Coating and Fabricating Ferroelectric Thin Films as Sensors and Solar Cells

Spin coating process with a modified spin coater is performed well, especially the second generation of modified spin coater, which has a maximum value of 18,000 rpm, is able for manufacturing/coating photonic crystal‐based ferroelectric thin films that require a high angular velocity (rpm). Ferroelectric thin films that use both 3000 and 6000 rpm have given good results in energy gap, electrical conductivity, etc. In addition, the modified spin coater has also produced several applications such as sensors in the device of blood sugar level noninvasively, sensors in the automatic drying system, sensors in the robotic system, and photovoltaic cells in the system of solar cells/panels which are being developed at present. These applications used ferroelectric material such as barium strontium titanate (BST), lithium niobate (LiNbO3), cuprous oxide (CuO), and lithium tantalate (LiTaO3)

The Effects of Lanthanum Dopant on the Structural and Optical Properties of Ferroelectric Thin Films

This chapter presents the effect of lanthanum (La) dopant on the structural and optical properties of the following ferroelectric thin films: barium strontium titanate (Ba0.5Sr0.5TiO3) (BST), lithium tantalate (LiTaO3), and lithium niobate (LiNbO3). We applied X‐ray diffraction, Fourier transform infrared spectroscopy (FTIR), and in some cases, atomic force microscopy to investigate the structural properties, functional groups, and particle size, as well surface roughness of these lanthanum‐doped thin films, respectively, whereas ultra violet‐visible (UV‐Bis) spectrometer was applied to investigate the optical bandgap of the La‐doped thin films. The results are in agreement with other previously researcher studies using different substrate materials. In general, the effect of La dopant highly affects both the structural and optical properties, changing significantly the grain size, surface roughness, and energy gap, and in certain cases, such as BST doped by La can change the material electric properties from insulator to semiconductor. Therefore, La‐doped thin films may offer promising applications in the future

Some Cosmological Consequences of Higher Dimensional Klein-Gordon-Rastall Theory

Using dynamical system analysis, we investigate some cosmological consequences of Rastall gravity coupled to a scalar field (called the Klein-Gordon-Rastall theory) with exponential scalar potential turned on in higher dimensions. From the critical points of the autonomous equations, we can determine the dominant components of the energy density in different cosmic eras. We obtain a fixed point representing a scalar field-matter-dominated era which corresponds to either a late-time or past-time attractor depending on the parameters used. According to this point, the inflationary phase, corresponding to past-time attractors, is given by unstable nodes, whilst the dark energy era, corresponding to late-time attractors, is represented by stable nodes. In the inflationary sector, power-law inflation can still occur in this Klein-Gordon-Rastall cosmological model. On the other hand, in the late-time sector, we find a nontrivial interplay between a scalar field with an exponential potential and the non-conservative energy-momentum tensor of the non-relativistic matter field (baryonic-dark matter) in curved spacetime plays a role as the dark energy. Based on such features, the Klein-Gordon-Rastall cosmology could be a promising candidate for describing both the early and late-time universe.Comment: 40 pages, 32 figures, typos corrected, abstract and all section revised as referee suggestion. Accepted in European Phys Jour

SIMULASI PERAMBATAN GELOMBANG ELEKTROMAGNETIK PADA KRISTAL FOTONIK 2D MENGGUNAKAN METODE FINITE DIFFERENCE FREQUENCY DOMAIN

Numerical simulations on two-dimensional photonic crystals with defects were analyzed using the Finite Difference Frequency Domain (FDFD). This approach consists of Maxwell's formulation that uses Central Finite Difference to place fields and materials at discrete points of the Yee grid, so that the matrix wave equation is obtained in the form of column vectors. Absorbent boundary conditions use Perfectly Matched Layer (PML) with fictitious magnetic conductivity to shed incoming waves at the edge of the domain calculation. Photonic crystals can be assumed to be a periodic lattice of dielectric material that produces the phenomenon of photonic band gap (PBG). The results of FDFD simulations are compared with the literature with a difference of 0.056. This small difference value means that this method is good enough to analyze PBG phenomena. For point defects and the accumulation of electromagnetic waves, linear defects are investigated and analyzed with spectral responses. Insertion of defects in photonic crystals will produce a photonic pass band (PPB). The simulation results show that PPB depends on the angle of arrival vector, material permittivity, and width of the defect structure

Simple Model for Simulating Characteristics of River Flow Velocity in Large Scale

We propose a simple computer based phenomenological model to simulate the characteristics of river flow velocity in large scale. We use shuttle radar tomography mission based digital elevation model in grid form to define the terrain of catchment area. The model relies on mass-momentum conservation law and modified equation of motion of falling body in inclined plane. We assume inelastic collision occurs at every junction of two river branches to describe the dynamics of merged flow velocity

Pembangunan Model Jaringan Saraf Tiruan untuk Memprediksi Kecenderungan Tipe Mediasi Orang Tua terhadap Penggunaan Internet oleh Anak

Mediasi orang tua sangat diperlukan agar dampak negatif penggunaan internet oleh anak yang tinggi di masa pandemi Covid-19 dapat diminimalisir. Penelitian ini dilakukan dengan membuat model jaringan saraf tiruan (JST) untuk mengetahui hubungan antara faktor dalam keluarga dan teknik mediasi orang tua di wilayah Bogor. JST penelitian ini dibangun menggunakan metode pembelajaran propagasi balik (backpropagation).  Faktor dalam keluarga yang diteliti sebagai masukan JST adalah usia orang tua, pendidikan, jumlah anak, usia anak, durasi menggunakan internet, serta jumlah media sosial yang digunakan. Jenis mediasi orang tua yang digunakan sebagai luaran jaringan adalah mediasi aktif penggunaan internet umum, mediasi aktif penggunaan bersama, mediasi pasif penggunaan bersama, mediasi pembatasan aktivitas berinternet, mediasi pembatasan penggunaan internet secara umum, mediasi aktif keamanan internet, mediasi pemantauan, dan mediasi teknis penggunaan internet. Data diperoleh melalui survei terhadap 282 orang tua di wilayah Bogor pada Februari-Juni 2021. Penelitian ini telah membangun model JST untuk memprediksi kecenderungan tipe mediasi orang tua dengan mean-squared error sebesar 0.05132. Model yang dihasilkan dapat dikembangkan lebih lanjut menjadi aplikasi edukasi sederhana yang dapat digunakan oleh orang tua untuk mengetahui jenis mediasi yang mereka lakukan. Dengan lebih memahami jenis mediasi yang mereka lakukan, kami berharap orang tua dapat memiliki pemahaman lebih baik mengenai mediasi orang tua dan dapat menerapkan teknik mediasi yang paling sesuai dengan kondisi yang mereka alami untuk mewujudkan ketahanan keluarga.Internet use by children is increasing during the Covid-19 pandemic. Therefore, parental mediation is needed to minimize the negative impact of internet use by children. This study aims to create a model based on an artificial neural network (ANN) to determine the relationship between factors in the family with parental mediation techniques in the Bogor area. The NN learning method used in this study is the Backpropagation learning method. We include the following factors in the study as the inputs of the NN, i.e. the age of parents, education, number of children, age of children, duration of using the internet, and number of social media accounts used. The types of parental mediation used as network outputs are active mediation of general internet use, active mediation of shared use, passive mediation of shared use, mediation of restrictions on internet activities, mediation of restrictions on general internet use, active mediation of internet security, monitoring mediation, and technical mediation of internet usage. We obtained the research data through a survey of 282 parents in the Bogor area in February-June 2021. This study has built an ANN model to predict the tendency of parental mediation types with a mean-squared error of 0.05132. The resulting model can be further developed into a simple educational application that can be used by parents to find out what type of mediation they are doing. By better understanding the types of mediation they do, we hope that parents can have a better understanding of parental mediation and can apply mediation techniques that are most appropriate to the conditions they experience to create family resilience