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Prediction of expansion of electric arc furnace oxidizing slag mortar using MNLR and BPN
Wen-Ten Kuo,Chuen-Ul Juang 사단법인 한국계산역학회 2017 Computers and Concrete, An International Journal Vol.20 No.1
The present study established prediction models based on multiple nonlinear regressions (MNLRs) and back-propagation neural networks (BPNs) for the expansion of cement mortar caused by oxidization slag that was used as a replacement of the aggregate. The data used for the models were obtained from actual laboratory tests on specimens that were produced with water/cement ratios of 0.485 or 1.5, within which 0%, 10%, 20%, 30%, 40%, or 50% of the cement had been replaced by oxidization slag from electric-arc furnaces; the samples underwent high-temperature curing at either 80°C or 100°C for 1-4 days. The varied mixing ratios, curing conditions, and water/cement ratios were all used as input parameters for the expansion prediction models, which were subsequently evaluated based on their performance levels. Models of both the MNLR and BPN groups exhibited R2 values greater than 0.8, indicating the effectiveness of both models. However, the BPN models were found to be the most accurate models.
Expansion behavior of low-strength steel slag mortar during high-temperature catalysis
Wen-Ten Kuo,Chun-Ya Shu 사단법인 한국계산역학회 2015 Computers and Concrete, An International Journal Vol.16 No.2
This study established the standard recommended values and expansion fracture threshold values for the content of steel slag in controlled low-strength materials (CLSM) to ensure the appropriate use of steel slag aggregates and the prevention of abnormal expansion. The steel slags used in this study included basic oxygen furnace (BOF) slag and desulfurization slag (DS), which replaced 5-50% of natural river sand by weight in cement mixtures. The steel slag mortars were tested by high-temperature (100°C) curing for 96 h and autoclave expansion. The results showed that the effects of the steel slag content varied based on the free lime (f-CaO) content. No more than 30% of the natural river sand should be replaced with steel slag to avoid fracture failure. The expansion fracture threshold value was 0.10%, above which there was a risk of potential failure. Based on the scanning electron microscopy (SEM) analysis, the high-temperature catalysis resulted in the immediate extrusion of peripheral hydration products from the calcium hydroxide crystals, leading to a local stress concentration and, eventually, deformation and cracking.
Analytical model of expansion for electric arc furnace oxidizing slag-containing concrete
Chun-Ya Shu,Wen-Ten Kuo,Chuen-Ul Juang 사단법인 한국계산역학회 2016 Computers and Concrete, An International Journal Vol.18 No.5
This study applied autoclave expansion and heat curing to accelerate the hydration of concrete and investigated how these methods affect the expansion rate, crack pattern, aggregate size effect, and expansion of electric arc furnace oxidizing slag (EOS)-containing concrete. An expansion prediction model was simulated to estimate the expansion behavior over a long period and to establish usage guidelines for EOS aggregates. The results showed that the EOS content in concrete should range between 20% and 30% depending on the construction conditions, and that coarse aggregates with a diameter of ≥4.75-mm are not applicable to construction engineering. By comparison, aggregates with a size of 1.18-0.03 mm resulted in higher expansion rates; these aggregates can be used depending on the construction conditions. On Day 21, the prediction model attained a coefficient of determination (R2) of at least 0.9.
Design and Implementation of Power-Saving Multicast Routing Protocols for Wireless Sensor Networks
Yu-Zhi Huang,Wen-Jiunn Liu,Kai-Ten Feng 보안공학연구지원센터 2008 International Journal of Software Engineering and Vol.2 No.2
How to provide low energy consumption and high packet delivery ratio are considered the major issues in the protocol design for the Wireless Sensor Networks (WSNs). The main focus of this paper is to reduce the number of data transmissions within the WSNs for decreasing the energy consumption of the sensor nodes. In the wired networks, the Steiner-Tree is regarded as the optimal approach for constructing the multicast structure for specific senders and receiver. However, the results can not be directly applied to the wireless environment. In this paper, an Energy Conserving Multicast Routing (ECMR) protocol is proposed to reduce the total number of relaying nodes for the construction of a multicast tree. It is designed to be a heuristic scheme since achieving a minimal cost multicast tree is considered an NP-Hard problem in the wireless broadcast environment. Moreover, the proposed algorithm is implemented on practical embedded platforms for performance evaluation. Comparing with the existing multicast routing protocol, the experimental results show that the proposed ECMR scheme can provide better energy conservation while the packet delivery ratio is still preserved.
Expansion behavior of concrete containing different steel slag aggregate sizes under heat curing
Chun-Ya Shu,Wen-Ten Kuo 사단법인 한국계산역학회 2015 Computers and Concrete, An International Journal Vol.16 No.3
This study investigated particle expansion in basic oxygen furnace slag (BOF) and desulfurization slag (DSS) after heat curing by using the volume method. Concrete hydration was accelerated by heat curing. The compressive strength, ultrasonic pulse velocity, and resistivity of the concrete were analyzed. Maximum expansion occurred in the BOF and DSS samples containing 0.30-0.60 mm and 0.60-1.18 mm particles, respectively. Deterioration was more severe in the BOF samples. In the slag aggregates for the complete replacement of fine aggregate, severe fractures occurred in both the BOF and DSS samples. Scanning electron microscopy revealed excess CH after curing, which caused peripheral hydration products to become extruded, resulting in fracture.
Prediction of ions migration behavior in mortar under 2-D ALMT application to inhibit ASR
Chih-Chien Liu,Wen-Ten Kuo 사단법인 한국계산역학회 2014 Computers and Concrete, An International Journal Vol.14 No.3
This study investigated four electric field configurations of two-dimensional accelerate lithium migration technique (ALMT), including line-to-line, plane-to-line, contour-to-line and plane-to-plane, and analyzed the ion migration behavior and efficiency. It was found that the free ion distribution diagram and voltage distribution diagram were similar, and ions migrated in the power line direction. The electrode modules were used for the mortar specimen with w/c ratio of 0.5. The effectively processed areas accounted for 14.1%, 39.0%, 49.4% and 51.4% of total area respectively on Day 28. Larger electrode area was more advantageous to ion migration. In addition, it was proved that the two-dimensional electric field could be divided into different equifield line active regions, and regarded as affected by one-dimensional electric field, and the ion migration results in various equifield line active regions were predicted by using the duration analysis method based on the theoretical model of ion migration obtained from one-dimensional test.
Equifield line simulation and ion migration prediction for concrete under 2-D electric field
Chih-Chien Liu,Chun-Yao Huang,Wen-Ten Kuo 사단법인 한국계산역학회 2013 Computers and Concrete, An International Journal Vol.12 No.4
This study attempted to find a proper method applicable to simulating practical equifield lines of two-dimensional Accelerate Lithium Migration Technique (ALMT), and evaluate the feasibility of using the theoretical ion migration model of one-dimensional ALMT to predict the ion migration behavior of two-dimensional ALMT. The result showed that the electrolyte or carbon plate can be used as matrix to draw equifield line graph similar to that by using mortar as matrix. Using electrolyte electrode module for simulation has advantages of simple production, easy measurement, rapidness, and economy. The electrolyte module can be used to simulate the equifield line distribution diagram in practical two-dimensional electrode configuration firstly. Then, several equifield line zones were marked, and several subzones under one-dimensional ALMT were separated from various equifield line zones. The theoretical free content distribution of alkali in concrete under two-dimensional electric field effect could be obtained from duration analysis.