Publikasi Universitas Mercu Buana
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Forecast of sugar demand in retail using SARIMA and decomposition models case study: a retail store in Indonesia
No full textThis study discusses forecasting demand in a retail store, focusing on sugar, which is a staple food in Indonesia, as the research object. Despite its importance and forecast challenge, there is no research has been done on sugar at the retail level. This study aims to find the most suitable forecast model that can capture data patterns well to give a good prediction of sugar sales in a retail store in Indonesia by comparing SARIMA and decomposition models. This study uses a stationary test and ACF pattern analyses to prepare the data, a residual test to avoid forecast bias, cross-validation to check the forecast model performance, and MAPE as the performance indicator. SARIMA (0,0,0)(0,1,1)8 and multiplicative decomposition with 3 periods of double-moving average models are chosen. Both models have similar patterns but different slopes because the decomposition model is more sensitive to data patterns, resulting in different MAPEs, which are 15.22% and 13.64%. Despite the popularity of SARIMA, decomposition can be an interesting alternative to use since it can capture trend data patterns better. However, the short forecast period is preferable for the decomposition model to avoid high trend slope prediction in the long run, leading to more frequent forecast activity and higher resources compared to SARIMA
Experimental study and optimisation of flexural properties of 3D-printed polylactic acid for energy-storing-and-returning prosthetic foot
No full textA prosthetic foot with energy-storing-and-returning capabilities requires high strength to prevent damage, high rigidity for stability, and low weight for user comfort. Therefore, efforts are needed to optimise the properties of the 3D-printed prosthetic foot. Based on the literature review, a research gap remains in understanding the complex interactions among 3D printing parameters that improve flexural properties, minimise mass, and reduce printing time. This study investigated how infill density, layer thickness, shell thickness, and their interaction affect the flexural strength-to-mass ratio, flexural modulus of elasticity, strain, and required printing time of the 3D-printed product. The experimental parameter ranges are infill density (40–60%), layer thickness (0.2–0.3 mm), and shell thickness (0.8–1.6 mm). A case study was conducted to optimise these parameters using the Response Surface Methodology with the Box-Behnken Design. The experimental data were fitted to a quadratic model, and Analysis of Variance determined the significance of individual factors. A gradient-based algorithm then identified the optimal parameter combinations. Results indicated that shell thickness was the most influential factor on the flexural strength-to-mass ratio and flexural modulus. Additionally, the interaction between layer height and shell thickness significantly affected strain, while infill density impacted printing time. The optimal values obtained were 32.5722 MPa/gram for the flexural strength-to-mass ratio, 2727.06 MPa for the modulus, 0.0522 for the strain, and 757.7788 seconds for the printing time. The novelty of this research lies in presenting how the interaction between shell thickness, layer thickness, and infill density affects process productivity and material efficiency while preserving product performance
Evaluation of double-stage Anaerobic Fluidized Bed Reactor (AFBR) for digestion of leachate: correlation of kinetic parameter with operational condition and process
No full textThe objective of this study is to investigate the performance of using an advanced fluidized bed reactor (AFBR) of a double column configuration in breaking down leachate into biogas. The relationship of the kinetic parameters with the operating conditions and the performance of the double-column reactor during anaerobic digestion was examined. The substrate concentration, microorganism population, hydraulic retention time value, growth rate, and death rate of microorganisms were employed as reference points for evaluating anaerobic digestion performance and assessing the operating conditions. The results demonstrated that there was no notable correlation between the formation of volatile fatty acids (VFA) in the acidogenic reactor (R1), the degradation of VFA in the methanogen reactor (R2), and the methane production rate in the methanogen reactor (R2). The simulation results for VFA formation (dCVFA1/dt) and VFA degradation (dcVFA2/dt) exhibited a tendency to overestimate when operated at low HRT and underestimate at short HRT compared to the experimental results. The steady state of the simulation results exhibited a faster rate of progression than the experimental outcomes. The fitting data for Ksx1 and Ksx2 predominantly comprise dynamically evolving values that exert an influence upon um1 and um1, as well as kd1 and kd2, when the reactor is operated in continuous mode. Furthermore, the factors of inhibitor compounds and microorganism adaptation were not observed across all HRT values in this investigation.
Evaluation of FIR bandpass filter and Welch method implementation for centrifugal pump fault detection
No full textThe motivation for this research is the high vibration observed during the operation of the centrifugal cooling water pump. Our study aims to assess the pump's state and check the vibrations to ensure the factors underlying the fault of the centrifugal pump in the alkaline chlorine factory. While previous studies have primarily used spectral amplitude results from the Fast Fourier Transform to analyze engine vibrations, we propose a different approach in this study. We employ the Finite Impulse Response (FIR) Bandpass Filter and the Welch Method, a practical analytic approach. The ISO 10816-3 standard is a benchmark of the RMS value to determine the pump's condition. The FIR Bandpass Filter and Welch Method prove to be highly effective in describing and modifying the vibrational signals of the centrifugal pump. The approach is particularly beneficial as it is consistent across sample rate settings, reduces the vibration of amplitude low, produces a smoother spectrum with only the primary frequency component, and segments the vibration signal into the frequency band-aids to identify the primary vibration source. The diagnostic results reveal increased vibrations at 1x, 2x, and ball pass frequency (BPF), indicating impeller damage and disappearance. Post-repair, the vibration value experiences a significant drop, as per the fault analysis results, further confirming the high effectiveness of our approach. These findings have practical implications for the maintenance and fault diagnosis of centrifugal pumps, providing a reliable and effective method for identifying and addressing issues.
Innovative bio-inspired solar cells using fly ash-based dye-sensitized cells with fruit extract enhancements and Averrhoa bilimbi electrolyte
No full textThis study responds to the urgent need for renewable energy in Indonesia, driven by climate change and the energy crisis, by developing dye-sensitized solar cells (DSSCs) using locally sourced, eco-friendly materials. Traditional silicon-based photovoltaic cells, which have plateaued at 27% efficiency, are costly and environmentally unfriendly, leading to the demand for alternatives like DSSCs, which offer lower production costs, flexibility, and effective performance in diffuse light. The research focuses on designing DSSCs with Fe and Mg extracted from fly ash as counter electrodes, dragon fruit peel as a natural dye sensitizer, and Averrhoa bilimbi as an electrolyte booster. UV-Vis spectroscopy demonstrated that dragon fruit dye absorbs light effectively in the 360-700 nm range, peaking at 550 nm, making it an ideal sensitizer for wide-band gap semiconductors. Voltage output tests showed that Fe-doped DSSCs consistently outperformed Mg-doped ones, with Fe-based cells generating a maximum voltage of 413 mV compared to 163 mV for Mg-based cells. Long-term testing over three months further demonstrated Fe-doped cells' superior performance, peaking at 454.6 mV, while Mg-doped cells reached 261.96 mV. These results highlight Fe's effectiveness as a doping material, improving DSSC efficiency and supporting the use of natural dyes and sustainable materials. The study aligns with prior research on the critical role of material properties and solar irradiance in DSSC performance, demonstrating the potential of using fly ash and natural dyes for efficient solar energy solutions in South Sumatra. Future research will focus on optimizing material composition for enhanced performance
Identifying degradation pathways at Sembrong Dam, Johor: insights from Sentinel-2 satellite imagery and NDVI analysis
No full textThe study is to evaluate the catchment area mapping at Sembrong Dam in Johor, Malaysia and identify potential transit pathways contributing to dam water degradation while implementing targeted mitigation works. The analysis involved the surface runoff patterns and topographical/geographic data via a digital elevation model (DEM), providing insights into terrain characteristics, slope, and flow directions to hydrological dynamics that significantly contribute to water resource management. This study focuses on producing the catchment area map with satellite imagery and defining the transit pathway that potentially causes water degradation in a reservoir. The analysis uses satellite images from sentinel-2 processing to generate a detailed runoff map and DEM of the catchment area surrounding the dam. The study uses Red Bands (RED) and Near-Infrared Bands (NIR) to process sentinel satellite images to create NDVI maps. Data is uploaded as Raster data in QGIS, and NDVI calculations are performed to transform raw satellite data into an index for vegetation health. NDVI values are classified into different colour classes to visualize the condition of the study area. High NDVI values indicate higher concentrations of agriculture nutrients, potentially triggering eutrophication in watersheds through surface runoff. The study analyzed a 66.89 km2 reservoir catchment area using runoff maps. NDVI analysis showed vegetation density and plant health, with robust vegetation in the dam-surrounded region with an NDVI value of 0.8. However, due to its narrow geography and deep lakes, the northeastern region is slightly polluted and susceptible to algae growth. The study aims to improve understanding of LULC and water conditions by analyzing pollution levels using remote sensing data, DEM, and NDVI for mitigation strategies
Renewable energy in chemical industrial buildings for cost performance
No full textDue to their potential benefits for a variety of industries, blockchain technologies have recently attracted a lot of attention from the scientific community as well as the business community. Blockchain provides distributed, secure, permissioned transactional ledgers, that successfully deal with these problems. The purpose of this study is to present a new conceptual framework that combines blockchain technology with building information modeling. This framework is specifically designed for smart contracts and digital transactions in the chemical industry's retrofitting of green buildings. Within this particular context, the main goals are to improve cost-effectiveness, bolster cybersecurity measures, improve information sharing and management, expedite payment transactions, and advance sustainability. In Cilegon, Banten, Indonesia, a chemical facility was the study's location. The study also makes use of partial least squares structural equation modeling
Analisis Pengaruh Preferensi Belanja Konsumen Terhadap Keputusan Pembelian Sembako dalam Struktur Dual Channel Supply Chain
No full textDual Channel Supply Chain (DCSC) merupakan strategi dalam manajemen rantai pasok yang menggunakan dua jalur distribusi yang berbeda yaitu saluran fisik tradisional dan saluran online atau digital untuk mendistribusikan produk kepada pelanggan. Perkembangan e-commerce yang mendorong penerapan DCSC menimbulkan potensi konflik antara saluran offline dan online dalam memenuhi permintaan konsumen. Dalam penelitian ini menggunakan push pull mooring (PPM) untuk mengidentifikasi perilaku pelanggan (customer behavior) beralih dari saluran luar jaringan menjadi dalam jaringan. Variabel push mencakup satisfaction, information searching behaviour, perceived price, and perceived service quality. Variabel mooring mencakup attitude towards switching, switching cost, habit dan subjective norm. Variabel pull terdiri dari responsiveness dan attractiveness. Hasil penelitian menunjukkan bahwa ketiga variabel diatas dapat diterapkan dalam menentukan strategi operasional dan taktis dalam mengantisipasi volatilitas dalam customer behaviour
Prototipe Alat Ukur Ketinggian Coil Block Pada Kereta Kerja Kereta Cepat Indonesia China
No full textPembuatan desain prototipe alat ukur ketinggian Coil Block Track Circuit Reader pada Kereta Kerja KCIC dilakukan secara konvensional dengan mengukur secara manual dari permukaan rel mengunakan mistar. Pencahayaan yang didapat tidak maksimal karena coil blok track circuit reader berada di underfloor sehingga menyulitkan dalam pengukuran. Hal ini memungkinkan kurangnya tingkat keselamatan, kepraktisan pencatatan dan akurasi hasil pengukuran. Tujuan dari penelitian ini adalah membuat prototipe alat ukur ketinggian track circuit reader untuk meningkatkan akurasi dan keselamatan petugas. Metode yang dilakukan ini berdasarkan perancangan dan pembuatan alat. Hasil pengukuran penyimpangan Prototipe Alat ukur ketinggian Coil Block Track Circuit Reader yang dilakukan oleh 4 orang adalah 0.0067 %, sedangkan hasil penyimpangan metode manual adalah 1.132 %. Berdasarkan data tersebut, terdapat penurunan hasil penyimpangan dengan kemampuan akurasi alat dua angka di belakang koma dilengkapi display dan hasil pencatatan otomatis terekam pada excel. Sehingga tercapainya keakuratan pengkuran Coil Track Circuit Reader sesuai dengan standar, memudahkan perekaman data pengukuran serta meningkatkan keselamatan pekerja
Antecedents of Job Satisfaction to Moonlighting Intentions Mediated by Organizational Commitment of Private Companies in Jakarta
No full textThis research aims to examine the influence of Moonlighting Intention and Personal Reasons on Job Satisfaction and Organizational Commitment, with a particular focus on the mediating role of Organizational Commitment. The study was conducted among employees working in private companies located in Jakarta, Indonesia. A total of 184 respondents participated, representing diverse educational backgrounds, working experiences, and demographic characteristics. The research applied a quantitative approach with data collected through a structured online questionnaire distributed via Google Forms, utilizing a cross-sectional survey design. Data were analyzed using descriptive statistics and hypothesis testing. The results indicate that Moonlighting Intention has a positive and significant impact on both Job Satisfaction and Organizational Commitment. However, Personal Reasons do not significantly influence Organizational Commitment or Job Satisfaction. Furthermore, Organizational Commitment shows a positive and significant effect on Job Satisfaction, but it does not function as a mediating variable between Moonlighting Intention or Personal Reasons and Job Satisfaction.These findings suggest that employees' intention to engage in additional jobs outside their primary employment does not necessarily reduce their organizational commitment or satisfaction levels. Conversely, personal motivations alone are insufficient to enhance employees’ commitment or satisfaction without organizational support. The study highlights the importance of strengthening organizational policies that foster employee engagement, loyalty, and satisfaction, particularly in the context of balancing external work activities and organizational responsibilities. The results contribute to the growing body of research on employee behavior in the private sector, providing valuable insights for organizational management to develop more effective human resource strategie