Improving radar rainfall estimation accuracy in the composite area of Takhli and Sattahip radars using spatial and hourly time-varying bias adjustment

2026-09-01T10:01:24+07:00

In estimating rainfall over the composite coverage area of the Takhli and Sattahip radars, the use of a composite Z–R relationship may still result in residual errors due to differences in the physical characteristics of rainfall. These differences can be attributed to the effects of the Earth’s curvature, variations in terrain characteristics, and event-to-event differences in rainfall, including variations in the spatial distribution of raindrops over time. In this study, a total of 267 rainfall events occurring between August 2018 and August 2020 were collected and analyzed. The dataset consisted of hourly rainfall measurements from 47 automatic ground-based telemetry stations and radar reflectivity data obtained within a 240 km detection range of the Takhli and Sattahip radars. These data were used to determine pixel-specific bias adjustment factors that varied on an hourly basis using the Inverse Distance Weighting (IDW) method. The adjustment factors were estimated from neighboring pixels with known values derived from both radar observations and automatic ground-based telemetry stations located within a 20 km radius of each target pixel. The results showed that the Composite radar rainfall intensity estimated using the Z = 138R^1.6 relationship for the Takhli radar and the Z = 170R^1.6 relationship for the Sattahip radar, combined with the proposed hourly time-varying bias adjustment factors, provided the greatest improvement in radar rainfall estimation accuracy over the composite coverage area of the Takhli and Sattahip radars. This approach yielded the lowest RMSE (Root Mean Squared Error), MAE (Mean Absolute Error), and BIAS values compared with the other bias adjustment methods. The proposed approach improved rainfall estimation accuracy by 50.24%, 16.83%, and 8.33% in terms of RMSE, MAE, and BIAS, respectively, compared with the unadjusted composite rainfall intensity estimated using the Z = 138R^1.6 relationship for the Takhli radar and the Z = 170R^1.6 relationship for the Sattahip radar.

Design and performance optimization of a laboratory scale distiller for high-purity bioethanol production from biomass feedstocks

2026-07-30T21:11:41+07:00

This study presents the design, fabrication, and performance evaluation of a laboratory-scale packed-column distillation system to produce high-grade hydrous bioethanol from fermented mango (Mangifera indica) waste, a locally abundant agricultural residue, using low-cost, locally available materials. The system was engineered as a cost-effective and scalable solution for biomass-based ethanol purification suited to decentralized, small-scale operations. The distillation apparatus incorporates a configurable reflux column utilizing two alternative packing materials steel wool (A1) and Raschig rings (A2) to enhance vapor-liquid contact and improve separation efficiency. Mango waste was collected, prepared, and fermented to produce a crude bioethanol wash, which was then processed at three initial ethanol concentrations (40%, 60%, and 80%, designated B1, B2, and B3, respectively). The two packing materials and three feed concentrations were arranged in a Completely Randomized Design (CRD) in a 2 × 3 factorial layout, replicated three times (18 experimental runs), and the resulting data were analyzed using two-way ANOVA and linear regression. The results demonstrate that packing material significantly influenced system performance. Raschig rings achieved superior outcomes overall, yielding ethanol purity up to 97.83%, a mean distillation efficiency of 73.37% (compared with 65.45% for steel wool), and a mean ethanol recovery of 41.55% (overall mean across both packing materials: 41.51%). Distillation rates ranged from 2.4 to 3.89 L/h depending on feed concentration and packing configuration. Operational parameters showed a rapid start-up time (5-10 minutes) and efficient thermal performance within a boiling range of 70-83°C. A techno-economic assessment indicates that the system is financially viable for small-scale deployment, with a low capital investment (₱6,500) and a total annual operating cost of ₱51,477 against an annual production capacity of 1,648.8 L, giving a unit production cost of approximately ₱31.22/L. At an assumed selling price of ₱35.00/L, the system generates an estimated annual net income of ₱5,496, a payback period of 1.18 years, and a return on investment of 84.55%. (1 US Dollar = 62 ₱) The study demonstrates the technical and economic feasibility of an optimized packed-column distillation system for purifying mango waste-derived bioethanol, offering a sustainable pathway for decentralized biofuel production and agricultural waste valorization in the Philippines.

Agricultural and Biological Engineering

Improving radar rainfall estimation accuracy in the composite area of Takhli and Sattahip radars using spatial and hourly time-varying bias adjustment

Design and performance optimization of a laboratory scale distiller for high-purity bioethanol production from biomass feedstocks