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Blueshift of the optical bandgap in ZnO films by controlling the substrate temperature
Full text linkThis study investigates the growth of ZnO thin films using the spray pyrolysis method, focusing on the effect of substrate temperature on the optical bandgap. By varying the deposition temperature from 300 to 500 °C, we aim to understand how temperature influences the optical properties of ZnO films. The films were characterized using X-ray diffraction (XRD) and UV-visible spectroscopy (UV-Vis). At 300 °C, the absorption was lowest, and the optical bandgap increased from 3.20 eV at 300 °C to 3.70 eV at 500 °C. These findings are crucial for developing ZnO materials for optoelectronic applications using an efficient and cost-effective deposition method
Analysis of GDP in Countries allied to Indonesia using a Combination of the GSTAR Model and Verification using Statistical Quality Control
No full textThe Generalized Space-Time Autoregressive (GSTAR) model is used to model GDP growth rates in Indonesia, Malaysia, Singapore, and Brunei Darussalam, allied countries. Southeast Asian countries have cultural and historical linkages and often share economic tendencies. GSTAR is used because it can represent GDP dynamics' complex spatial and temporal relationships. Historical GDP data for the four countries from 1975 to the present is collected. The GSTAR model models regional interdependence and temporal patterns in these economies' geographical and temporal linkages. To test GSTAR model accuracy and robustness, control chart analysis is done. Control charts help monitor and assess economic model stability. The data used in this study is GDP data in Indonesia, Malaysia, Singapore, Brunei Darussalam, and Thailand, was collected from 1975 to 2021. This study discusses GSTAR model projections with actual GDP growth rate data to identify economic abnormalities in these linked countries. This research has major consequences for regional politicians, economists, and businesses. Policy decisions, investment strategies, and GSTAR model economic forecasts can benefit from understanding these countries' GDP growth interdependencies and patterns. Control chart analysis also assures the model accurately tracks economic trends over time. Finally, the GSTAR model and control chart analysis give a complete framework for modeling and testing allied GDP growth rate
PERANCANGAN INTERIOR "ARDEAKON CAFE AND GALLERY" DENGAN PENDEKATAN EKO-DESAIN DI TEMANGGUNG
Full text linkKalangan anak muda gemar berkumpul dan bersantai di cafe. Kegiatan berkumpul yang kian meningkat turut meningkatkan keberadaan cafe. Pembangunan cafe seringkali kurang memperhatikan permasalahan global sepeti perubahan iklim, polusi, dan penurunan keanekaragaman hayati, sehingga hal ini memberikan dampak bagi lingkungan sekitarnya. Pembangunan cafe dengan pendekatan ekodesain penting guna mendukung keseimbangan dan kelestarian lingkungan. Seiring keinginan brand Ardeakon dalam melakukan perluasan dari usaha interior build dan peralatan otomatis ke sektor retail food and beverage di Kota Temanggung, maka identitas brand Ardeakon perlu diterapkan ke dalam desain interior melalui perancangan interior Ardeakon cafe and gallery dengan tepat. Kualitas suatu usaha dipengaruhi kualitas brand dan desain interior yang dapat diaplikasikan ke dalam tempat usaha. Identitas brand dalam desain interior yang baik akan membantu mempermudah pengunjung untuk mengingat dan mengenali ciri khas serta karakter cafe dan gallery ini. Perancangan interior Ardeakon cafe and gallery yang menggunakan metode perancangan design thinking dan pendekatan eko-desain menekankan organisasi ruang yang efektif dan efisien, penggunaan material yang ramah lingkungan, efisien dalam pemakaian energi dan sumber daya, serta mengaplikasikan penerapan identitas brand dengan tepat. Hasil perancangan interior Ardeakon cafe and gallery dapat meningkatkan kesadaran masyarakat terhadap isu-isu lingkungan dan memberikan kontribusi dalam mengurangi dampak lingkungan. Selain itu, pembangunan cafe dan gallery yang unik ini dapat menarik perhatian dan dikenal masyarakat, serta dapat menjadi salah satu daya tarik wisata bagi Kota Temanggung
Comparative Risk Prioritization in the Initiation Phase of the Pagerungan Besar Photovoltaic Plant: A Failure Mode and Effect Analysis (FMEA) and Risk Matrix Approach
Full text linkPhotovoltaic (PV) power plant projects in East Java often face challenges during the initiation phase due to inadequate risk assessments. This phase is crucial for ensuring the project's long-term success; however, suboptimal risk identification has caused project delays. In the risk assessment process, high-priority risks need to be mitigated, but differences in the methods used can result in varying risk priority outcomes. One of the methods that can be used is Failure Mode and Effect Analysis (FMEA), while according to internal regulations at PT PLN (Persero), the Risk Matrix is applied. By using these two methods, the differences in the resulting risk priority rankings can be identified. Both tools rely on evaluations from experts experienced in decision-making during the initiation phase of PV power plant projects. From the analysis, 12 risks were identified during the initiation phase of the Pagerungan Besar PV power plant project. The highest-priority risks identified include Suboptimal feasibility study (Risk Priority Number/RPN: 74.27), unfavorable outcomes for the organization/company (RPN: 68.96), lack of budget (RPN: 64.00), and stakeholder Intervention (RPN: 53.69). Meanwhile, by plotting the Severity Level and Occurrence Level of each risk on the Risk Matrix according to PT PLN (Persero) regulations, the highest-priority risks identified include Suboptimal feasibility study (Extreme Risk Level, Zone E5), location-related issues (Extreme Risk Level, Zone E5), non-compliance with regulations (Extreme Risk Level, Zone E5), and suboptimal project team (Very High Risk Level, Zone D5). The two risk assessment methods produced different prioritizations, potentially impacting mitigation strategy decisions. This variation highlights the need for further analysis to ensure accurate and reliable risk prioritization, which is critical for project success and efficient resource allocation. Future studies should focus on evaluating prioritization methods to support effective decision-making and ensure timely project implementation in line with the targeted Commercial Operation Date (COD)
Light-Emitting Diode for Mitigating Horseshoe Crab (Limulidae) Bycatch of Bottom Gillnet Fishery for Blue Swimming Crab in the Waters of Ambulu Village, Cirebon Regency
Full text linkMimi, a term for horseshoe crabs (Limulidae), often constitutes an unintended bycatch in blue swimming crab (BSC) fisheries employing bottom gillnet fishing gear. Three horseshoe species found in Indonesia have been designated as ETP species. This research aims to test the efficacy of red LED Cree lights in BSC bottom gillnet fisheries to reduce horseshoe crabs bycatch. The experimental fishing approach was employed in the waters of Ambulu Village, Cirebon Regency, with 17 trips as replication. Two sets of gillnets, as control and treatment (equipped with LED lights), respectively, were utilized in the study. Data collected were the number of species and individuals of targeted species (BSC) and horseshoe crab as bycatch resulting from the BSC gillnet operations in both control and treatment nets. A descriptive analysis was used for catch composition. Statistical analyses, including paired sample t-tests and Wilcoxon tests, were conducted on the horseshoe crab bycatch and BSC catch data to test differences between the control and treatment nets. The most abundant catch consisted of crab (Actaeodes tomentosus), with 82 individuals captured in the treatment nets and 87 in the control nets. Blue swimming crab (Portunus pelagicus) caught 76 and 53 individuals in the treatment and control nets, respectively. The bycatch of horseshoe crabs (Limulidae) in the treatment and control nets of 10 and 27 individuals, respectively. The analysis revealed that the BSC catch in the treatment nets did not significantly differ from that in the control nets. Conversely, a significant difference was observed in the horseshoe bycatch between the treatment and control nets. Incorporating red LED Cree lights resulted in a 35.79% increase in the BSC catch and a 62.96% reduction in the horseshoe bycatch
Forecasting Tourist Arrivals in Bali: A Grid Search-Tuned Comparative Study of Random Forest, XGBoost, and a Hybrid RF-XGBoost Model
Full text linkTourism planning, infrastructure growth, and economic stability. This study presents an extensive comparative evaluation of Random Forest (RF), Extreme Gradient Boosting (XGBoost), Long Short-Term Memory (LSTM), and a novel Hybrid RF-XGBoost model in the prediction of monthly international tourist arrivals. A full time series dataset of a ten-year period (2014–2024) from the Central Bureau of Statistics of Bali was used for training and testing the models. Hyperparameter optimization using Grid Search with cross-validation (Grid Search CV) was used for all the machine learning models to obtain best predictive performance. Two robust metrics, Root Mean Squared Error (RMSE) and Mean Absolute Percentage Error (MAPE), were used to assess forecasting accuracy. Results show that the Random Forest model outperforms all competitors with lowest RMSE (41,772.68) and MAPE (6.30%), indicating high forecasting precision and robustness, especially during structural breaks such as the COVID-19 pandemic. The hybrid model also performs well, with LSTM indicating higher error rates, illustrating its shortcomings on small-to-medium-scale tourism time series. Besides, the study provides six-month ahead predictions (January–June 2025) with 95% prediction intervals, showing an ongoing trend of recovery. The findings affirm the superiority of bagging-based ensemble methods over polynomial-based methods in capturing nonlinearity, seasonality, and exogenous shocks in tourist demand. The study plugs the growing amount of data-driven tourism analytics by offering a reproducible, high-precision forecasting model for developing countries and seasonally driven destinations
Perencanaan Pengembangan Aset Fasilitas Berdasarkan Incremental Innovation Di Taman Kota Soreang
Full text linkTaman kota sebagai ruang terbuka hijau memberikan manfaat ekologis dan sosial bagi Masyarakat. Namun, kurangnya pemeliharaan, kurangnya ketersediaan fasilitas, dan kondisi fasilitas yang rusak membuat taman kota kurang diminati dan tidak dapat memenuhi kebutuhan pengunjung. Taman Kota Soreang merupakan salah satu Ruang Terbuka Hijau di Kabupaten Bandung yang memiliki luas kurang lebih 5.000 m². Taman Kota Soreang dikelola oleh Dinas Perumahan, Kawasan Permukiman, dan Pertanahan Kabupaten Bandung. Taman Kota Soreang memiliki permasalahan pada fasilitas yang meliputi: tidak memenuhi standar, rusak, dan ketidaklengkapan fasilitas. Tujuan dari penelitian terapan ini yaitu menghasilkan rencana pengembangan aset Taman Kota Soreang Kabupaten Bandung berdasarkarkan inovasi incremental untuk fasilitas di taman kota. Metode deskriptif dengan pendekatan kualitatif dan kuantitatif digunakan pada peneltian ini. Teknik pengumpulan data menggunakan wawancara, observasi, dokumentasi, dan benchmarking. Hasil penelitian ini adalah perlu disediakan fasilitas yang meliputi: 1) Aksesibilitas terdiri dari area parkir taman dan pagar taman; 2) Kenyamanan terdiri dari tempat duduk, Jalur pejalan kaki, Papan informasi digital, Vegetasi, toilet umum, Halaman rumput terbuka, dan WiFi; 3) keamanan terdiri Lampu taman, CCTV dua arah, dan terakhir; 4) Aktivitas sosial terdiri dari Fasilitas bermain, pangggung budaya, dan Trek Jogging. Biaya yang dihitung meliputi biaya biaya pembongkaran, biaya pembangunan, dan biaya pengadaan
Quantum Square Wells with Capacitive Walls: A Toy Model for Quantum Capacitors
Full text linkThis research aims to determine the energy quantization in a one-dimensional infinite square well modified by capacitive walls. The electric field inside the wall produces a linear potential. The solution to the Schrödinger equation is the Airy function for an infinite square well. Furthermore, the Wentzel–Kramers–Brillouin (WKB) approach is applied to finite wells, and the energy quantization for both cases based on this modified potential has been derived. In this paper, we also examine the quantum capacitance of the system, which is determined from the density of states and depends on dimensionality. The results obtained show that there is compatibility between the simple model that we work on and several systems, for example, graphene-base system
Cavitation Effect towards Graphene Oxide Synthesis Using Liquid Phase Exfoliation Method Assisted by Linear Alkylbenzene Sulfonate
Full text linkIn this study, graphene oxide was synthesized using the liquid phase exfoliation method. Graphene oxide synthesis was carried out by dispersing graphite powder in deionized water and adding linear alkylbenzene sulfonate surfactant, followed by exposure to ultrasonic waves at a frequency of 21 kHz. The graphite exfoliation process in this method took advantage of the cavitation phenomenon that occurred during the sonication process. The cavitation effect in this research was observed based on the characterization results of graphene oxide. The ultraviolet-visible spectroscopy results indicated that cavitation events influenced the emergence of the main absorption peak at a wavelength of 240 nm and a secondary peak at 287 nm. The X-ray diffraction results showed a phase transition from crystalline graphite to an amorphous phase, as indicated by the disappearance of sharp graphite peaks and the appearance of broad peaks at 2θ ≅ 18°. The Fourier transform infrared analysis showed that cavitation added oxygen groups to the graphene oxide produced, e.g.: -OH and C-OH, whose intensities increased after sonication. Scanning electron microscope analysis revealed sheet-like structures on the graphite surface. Based on the energy dispersive X-ray results, the C/O ratio of the graphene oxide sample was 68.99%. This aforementioned result supported the Fourier transform infrared results where an increase in the oxygen composition occurred after the sonication
Simulation of Solar Energy Harvesting on a 25-Meter Electric Passenger Ferry
Full text linkThis study investigates the integration of a solar photovoltaic system on the passenger ferry E.V. Calestia operating along Manila’s Pasig River. The ferry, equipped with dual 400 kW electric motors and a battery bank of 1848 kWh, is supplemented by 20 solar panels installed on its top deck. Using a Simulink-based simulation model, the research estimates the power output and cumulative energy generation based on panel specifications, solar irradiance, and system efficiency. Results show a maximum instantaneous power output of approximately 3 kW during peak sunlight and a total weekly energy generation of around 150 kWh. These findings demonstrate the potential of solar power to enhance the ferry’s energy sustainability by reducing reliance on conventional charging and lowering emissions, thus promoting greener maritime transport solutions in urban river environments