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The spent fluid catalytic cracking (SFCC), waste from the petroleum industry, is nonstop increasing and causing environmental pollution in Vietnam. This study is an attempt to recycle SFCC in pavement construction. The study investigated the effect of SFCC, as a filler material in the hot-mix asphalt (HMA), on the essential characteristics of the asphalt concrete mix. First, the optimum percentages of bitumen and SFCC rate were investigated based on the Marshall design method. The HMA with SFCC showed more enhanced stability, flow, and other Marshall properties than the asphalt concrete mixture with the optimum limestone filler of 5%. Besides, the effects of SFCC rates on Marshall characteristics were explored. Second, performance tests were conducted to compare the mix with the different optimum content fillers of SFCC, limestone, and Portland cement. The tests include wheel tracking, indirect tensile, fatigue, and dynamic modulus tests to evaluate the performance of HMA with SFCC. It was found that the asphalt mixture with the optimum SFCC filler content can enhance pavement performance and improve the rutting and cracking resistance of the asphalt pavement. [ABSTRACT FROM AUTHOR]

As a result of the increasing penetration of renewables in power systems, wind farms (WFs) have to satisfy the low-voltage ride-through (LVRT) requirement to stay connected to the power grid under fault conditions. This study proposes a novel method that uses the static synchronous compensator (STATCOM) to improve the LVRT capability of WFs during grid faults. The proposed method is based on the Taguchi method which involves orthogonal experiments. The allocation (locations and sizes) and fuzzy control gains of STATCOM are determined by the analysis of mean (ANOM) technique as part of the Taguchi method to achieve a robust design that is insensitive to variations of operating conditions and faults. The optimal STATCOM that is obtained by the proposed method is validated in both a single WF-infinite bus power system and the IEEE 39-bus power system. The simulation results show that the proposed method can enhance the LVRT capability of WFs. [ABSTRACT FROM AUTHOR]

As a result of the increasing penetration of renewables in power systems, wind farms (WFs) have to satisfy the low‐voltage ride‐through (LVRT) requirement to stay connected to the power grid under fault conditions. This study proposes a novel method that uses the static synchronous compensator (STATCOM) to improve the LVRT capability of WFs during grid faults. The proposed method is based on the Taguchi method which involves orthogonal experiments. The allocation (locations and sizes) and fuzzy control gains of STATCOM are determined by the analysis of mean (ANOM) technique as part of the Taguchi method to achieve a robust design that is insensitive to variations of operating conditions and faults. The optimal STATCOM that is obtained by the proposed method is validated in both a single WF‐infinite bus power system and the IEEE 39‐bus power system. The simulation results show that the proposed method can enhance the LVRT capability of WFs. [ABSTRACT FROM AUTHOR]

The static synchronous compensator (STATCOM) has attracted considerable attention because it can stabilise severe transients that are caused by power system disturbances. This study presents a novel interval type 2 fuzzy control system (IT2‐FCS)‐based controller for the STATCOM to stabilise bus voltages that are caused by faults or forced wind farm outages in a smart grid. Two IT2‐FCSs are presented to tune increments of the proportional integral (PI) controller, which are optimised by the gradient descent method. The IT2 fuzzy rules, involving upper and lower membership functions, result in a fast and stable system response. Since many possible scenarios may arise in the power system, the Taguchi method is used to design experiments using an orthogonal array, in which all scenarios are mutually independent. A power system that consists of a wind farm and STATCOM is studied. Comparative studies show that the proposed method is superior to traditional PI and type 1 FCS methods. [ABSTRACT FROM AUTHOR]

A temperature correction model for Falling Weight Deflectometer (FWD) backcalculated dynamic modulus was developed and validated in this study. FWD test was conducted to determine the field dynamic modulus, while the indirect tensile (IDT) dynamic modulus test was used to measure laboratory dynamic modulus. A temperature correction model was developed considering the effect of FWD loading frequency and pavement temperature. It was validated using field FWD data obtained from 26 Westrack pavement sections and Korean national highways' long-term pavement performance database. Also, the correction factor was compared with similar existing models using FWD testing in the field. It was observed from study results that the temperature correction model is capable of predicting the dynamic modulus accurately. [ABSTRACT FROM AUTHOR]

Spent fluid catalytic cracking (SFCC) is an industrial waste from oil refineries that is increasing nonstop in Vietnam and many places globally, and needs to be recycled. However, SFCC has various compositions depending on the fluid catalytic cracking (FCC) types and additives in the petroleum-refining industry. Thus, an experimental optimization procedure is needed to find the optimum addition of SFCC as a filler powder for asphalt–concrete mixtures. For this requirement, the study objective was an optimization procedure based on Taguchi parameter design employing an MMDC parameter. MMDC , developed using a robust multivariate statistical method called principal component analysis (PCA), is a representative parameter of required performance quality proposed by the Marshall mixture design. The Marshall mixture design was used to verify the asphalt–concrete mixture in which SFCC filler partly replaced traditional limestone (LS) filler. The effect of LS filler rate on mixture characteristics was used to determine the required range of values of MMDC. Also, Marshall characteristics based on various SFCC filler rates verified the optimum methodology result. The confirmation experiment results showed that the approach could find an optimum case with advantages in reducing asphalt binder content in the mixture and the number of specimens in the laboratory. Furthermore, the experimental results indicated that SFCC filler could enhance the Marshall characteristics of an asphalt–concrete mixture. [ABSTRACT FROM AUTHOR]

In this study, twenty-five yeast strains were isolated from soil samples collected in the gold mining ore in Gia Lai, Vietnam. Among them, one isolate named GL1T could highly tolerate Cu2+ up to 10 mM, and the isolates could also grow in a wide range of pH (3–7), and temperature (10–40 °C). Dried biomass of GL1 was able to remove Cu2+ effectively up to 90.49% with a maximal biosorption capacity of 18.1 mg/g at pH 6, temperature 30 °C, and incubation time 60 min. Sequence analysis of rDNA indicated this strain was closely related to Rhodotorula mucilaginosa but with 1.53 and 3.46% nucleotide differences in the D1/D2 domain of the 28S rRNA gene and the ITS1-5.8S rRNA gene-ITS2 region sequence, respectively. Based on phylogenetic tree analysis and the biochemical characteristics, the strain appears to be a novel Rhodotorula species, and the name Rhodotorula aurum sp. nov. is proposed. This study provides us with more information about heavy metal-tolerant yeasts and it may produce a new tool for environmental control and metal recovery operations. [ABSTRACT FROM AUTHOR]

An investigation on the influence of temperature (21.6-39.6°C) on the reaeration rate was performed. The recipient still water body was homogeneous and unstratified. The findings of the experimental study showed that the reaeration rate increases with temperature within the range of the temperature investigated. A mathematical model for estimating the reaeration rate is also presented. A new temperature correction factor for the conversion of the kinetic rate coefficient at different temperatures has been developed and was found to better reflect the reaction rates associated with the reaeration process. [ABSTRACT FROM AUTHOR]

A three-dimensional hydrodynamic-ecological lake model combined with field measurements and sampling was applied to investigate the impacts of floating photovoltaic (PV) systems on hydrodynamics and water quality in a shallow tropical reservoir in Singapore. The model was validated using field data and subsequently applied to predict temperature and water quality changes for a hypothetical 42 ha placement of floating photovoltaic panels, covering about 30% of the water surface and capable of generating up to 50 MW of energy. The impact of the panel placement was studied numerically. The area of the reservoir where panels are placed experiences both light limiting and reduced wind stress conditions. The model indicated an average water temperature increase of 0.3 °C beneath the panels, consistent with the field observation from a 1 ha demonstration installation. Comparisons of model results between the uncovered and covered areas reveal greater stability of the water column (increase in Richardson number from 2.3 to 3.3) and reduction in mixing energy (from 9 × 10–7 to 7 × 10–7 W/kg) under the PV panels. Furthermore, the model predicted that chlorophyll a, total organic carbon and dissolved oxygen concentrations would decline by up to 30%, 15% and 50%, respectively, under the photovoltaic panels. Total nitrogen and total phosphorus, averaged over the water column, increased by 10% and 30%, respectively, under the panels. Distant from the floating solar panels, temperature, stability and water quality were unaffected. [ABSTRACT FROM AUTHOR]

• The first combination of g-C 3 N 4 and the Re complex. • Investigation of photocatalyst CO 2 reduction under low-intensity visible-light irradiation. • Combination increases CO 2 conversion efficiency. • The photocatalysis mechanism follows the Z Scheme. Visible-light-driven photocatalyst g-C 3 N 4 /ReC converting CO 2 to fuels is a promising technology to solve climate change and energy demand. The redshift of the absorption region and the low luminescence intensity of g-C 3 N 4 /ReC contributes to enhance the photocatalytic activity. The CO formation and selectivity reach the highest TON CO = 28.81 at 210 min and 94.7%, respectively. The photocatalytic efficiency is enhanced 5.6 times compared ReC. The g-C 3 N 4 /ReC firstly combines of a semiconductor and ReC complex, contributes to the design of novel visible-driven photocatalytic systems working under low-intensity visible-light irradiation. [ABSTRACT FROM AUTHOR]

ABSTRACT: Precipitation data of finer timescale and higher spatial density are crucial for continuous hydrological modelling and flood risk assessment. Disaggregation methods are often used to transform the coarser‐timescale precipitation data into finer resolutions. The nonparametric approach based on method of fragments (MOF) has received broad attention in precipitation disaggregation literature, given its superiority in reproducing the at‐site statistical attributes. However, a detailed literature review has shown that the MOF‐based resampling approaches are mainly focused in the single‐site precipitation disaggregation context, which may subject to limitations such as the unavailability of at‐site precipitation records and the incapability to preserve the inter‐site correlation structure. To address these issues, we propose three resampling approaches based on MOF. The first approach is a single‐site interval‐based resampling approach which only draws subdaily fragment vectors from at‐site record. The second one extends the first one to a regionalized version where subdaily fragment vectors are drawn from both the at‐site and neighbouring stations. The third one is a multi‐site approach developed to preserve the observed inter‐site correlation. The performances of the three methods are evaluated with applications to daily‐to‐hourly precipitation disaggregation at six rain gauges in Singapore and eight precipitation stations in Wangkuai reservoir catchment in northern China. An elaborate list of performance measures, including standard validation statistics, spatial correlation, inter‐day connectivity, annual extreme analysis, and intra‐day dry and wet spell characteristics are used to assess the performance. The proposed three methods are shown to be effective in reproducing the at‐site attributes, and no significant deterioration of performance is observed when moving from the single‐site method to the regionalized and multi‐site versions. As expected, the multi‐site approach is the only one method that is able to reconstruct the spatial correlation in the disaggregated precipitation field. The approaches can be applied for daily‐to‐subdaily precipitation disaggregation in different regions. [ABSTRACT FROM AUTHOR]

Parameter calibration for computationally expensive environmental models (e.g., hydrodynamic models) is challenging because of limits on computing budget and on human time for analysis and because the optimization problem can have multiple local minima and no available derivatives. We present a new general-purpose parallel surrogate global optimization method P arallel O ptimization with D ynamic coordinate search using S urrogates (PODS) that reduces the number of model simulations as well as the human time needed for proper calibration of these multimodal problems without derivatives. PODS outperforms state-of-art parallel surrogate algorithms and a heuristic method, Parallel Differential Evolution (P-DE), on all eight well-known test problems. We further apply PODS to the parameter calibration of two expensive (5 h per simulation), three-dimensional hydrodynamic models with the assistant of High-Performance Computing (HPC). Results indicate that PODS outperforms the popularly used P-DE algorithm in speed (about twice faster) and accuracy with 24 parallel processors. • A new general-purpose parallel surrogate global optimization algorithm PODS. • PODS outperforms previous parallel methods on eight well-known test problems. • PODS defeats Differential Evolution on two expensive lake model calibration problems. • An open-source optimization toolbox including coupling PODS with Delft3D-FLOW. [ABSTRACT FROM AUTHOR]