Chen S.-H.,Nanhua University |
Chen M.-C.,Wufeng University
International Journal of Production Economics | Year: 2013
Estimation of Distribution Algorithms (EDAs) have recently been recognized as a prominent alternative to traditional evolutionary algorithms due to their increasing popularity. The core of EDAs is a probabilistic model which directly impacts performance of the algorithm. Previous EDAs have used a univariate, bi-variate, or multi-variable probabilistic model each time. However, application of only one probabilistic model may not represent the parental distribution well. This paper advocates the importance of using ensemble probabilistic models in EDAs. We combine the univariate probabilistic model with the bi-variate probabilistic model which learns different population characteristics. To explain how to employ the two probabilistic models, we proposed the Ensemble Self-Guided Genetic Algorithm (eSGGA). The extensive computation results on two NP-hard scheduling problems indicate the advantages of adopting two probabilistic models. Most important of all, eSGGA can avoid the computation effort overhead when compared with other EDAs employing two models. As a result, this paper might point out a next generation approach for EDAs. © 2012 Elsevier B.V. All rights reserved.
Lin T.-C.,Wufeng University
Information Sciences | Year: 2010
In this work, a two-pass switching rank-ordered arithmetic mean (TSRAM) filter that preserves image details while effectively suppressing impulse noise is proposed to improve the performance of switching-based median filters. The proposed filter mechanism includes an efficient impulse detector based on the Dempster-Shafer (D-S) evidence theory and a rank-ordered arithmetic mean filter that works by estimating the noise-free ordered mean values excluding the current pixel. A modified Dempster's combination rule is applied to the impulse detector. To improve filtering performance, a simple switching median filter is included to perform second-pass filtering. Experimental results show that the proposed filter outperforms many well-accepted switching-based median filters in terms of both noise suppression and detail preservation, providing excellent robustness at various percentages of impulse noise. © 2010 Elsevier Inc. All rights reserved.
Liou B.W.,Wufeng University
Thin Solid Films | Year: 2011
The fabrication and characterization of In xGa 1-xN/GaN-based solar cells that use In xGa 1-xN multiple quantum wells (MQWs) and a SiCN/Si(111) substrate are reported. Solar cell operation with a low dark current density (J d), a high open-circuit voltage (V oc), a high short-circuit current density (J sc), and a high fill factor (FF) is demonstrated. It was found that the proposed device and fabrication technology are applicable to the realization of solar cells with a low J d of 2.14 to 8.88 μA/cm 2, a high V oc of 2.72 to 2.92 V, a high J sc of 2.72 to 2.97 mA/cm 2, and a high FF of 61.51 to 74.89%. The device performance with various quantum-well configurations was investigated under an air mass 1.5 global solar spectrum. A high photovoltaic efficiency of 5.95% in the MQW sample over the p-i-n sample was observed. © 2011 Elsevier B.V. All rights reserved.
Lin T.-C.,Wufeng University
Expert Systems with Applications | Year: 2011
A novel decision-based fuzzy averaging (DFA) filter consisting of a D-S (Dempster-Shafer) noise detector and a two-pass noise filtering mechanism is presented in this paper. The proposed filter can effectively deal with impulsive noise, and a mix of Gaussian and impulsive noise. Bodies of evidence are extracted, and the basic belief assignment is developed using the simple support function, which avoids the counter-intuitive problem of Dempster's combination rule. The combination belief value is the decision rule for the D-S noise detector. A fuzzy averaging method, where the weights are constructed using a predefined fuzzy set, is developed to achieve noise cancellation. A simple second-pass filter is employed to improve the final filtering performance. Experimental results confirm the effectiveness of the new DFA filter both in suppressing impulsive noise as well as a mix Gaussian and impulsive noise and in improving perceived image quality. © 2011 Elsevier Ltd. All rights reserved.
Chi M.,Wufeng University |
Huang R.,National Taiwan Ocean University
Construction and Building Materials | Year: 2013
Binding mechanism and properties of alkali-activated fly ash/slag (AAFS) mortars with various ratios of fly ash to slag were investigated by compressive strength test, flexural strength test, water absorption test, drying shrinkage test, scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. Sodium oxide (Na2O) concentrations of 4% and 6% by cementitious material weight and liquid sodium silicate with modulus ratio (mass ratio of SiO2 to Na2O) of 1 were prepared as activators. The liquid/binder ratio was kept at a constant of 0.5. Test results show that both fly ash/slag ratio and the dosage of Na2O are two significant factors influencing the binding mechanism and properties of AAFS mortars. The hydration products of AAFS mortars investigated by SEM and XRD are mainly amorphous alkaline aluminosilicate and low-crystalline calcium silicate hydrate gel. With the exception of drying shrinkage, better properties, such as compressive strength, flexural strength and water absorption, have been obtained in AAFS mortars than comparable OPC mortars. Meanwhile, the binding mechanism and properties of AAFS mortars improved with an increase dosage of Na2O. AAFS mortars with a fly ash/slag ratio of 50/50 alkali-activated by Na 2O concentrations of 6% may be considered as the optimum mix design based on the results. © 2012 Elsevier Ltd. All rights reserved.
Chi M.,Wufeng University |
Huang R.,National Taiwan Ocean University
Cement and Concrete Composites | Year: 2014
Circulating fluidized bed combustion (CFBC) ash, which has such a high content of f-CaO and SO3, is a waste or by-product of petroleum coke combustion power stations. The purpose of this study is to investigate the effects of CFBC ash on the properties of roller compacted concrete (RCC). CFBC ash was used to replace fine aggregate with various dosages (5%, 10% and 15%) by weight. All mixtures were designed according to ACI 211.3R and prepared for testing. During casting, cylinders were vibrated and compacted with different pressures of 25 g/cm2, 50 g/cm2 and 75 g/cm2, respectively. Test results show that CFBC ash can increase the water absorption and effectively reduce the initial surface absorption. Meanwhile, CFBC ash has a positive effect on compressive strength, splitting tensile strength, and sulphate attack resistance of hardened RCC. SEM revealed that the main hydration products of specimens containing CFBC ash are AFt (ettringite), C-S-H (hydrated calcium silicate) and portlandite. Based on the presented observations and results, RCC with the dosage of 5% CFBC ash as fine aggregate replacement and the roller compaction pressure of 75 g/cm2 is recommended. © 2013 Elsevier Ltd. All rights reserved.
Lee Y.-C.,Wufeng University
Applied Mathematics and Information Sciences | Year: 2012
The Radio Frequency Identification (RFID) system plays an important role in authentication, security control, supply chain management, and inventory control. Due to market consideration, low-cost RFID systems have become very popular in recent years. In many applications, such as e-passport, RFID systems need security mechanisms to resist all possible attacks and security risks. However, because of extensive computation requirements and high memory space demand for most security mechanisms, they are not suitable for low-cost RFID tags. In this paper, we propose two ultralightweight authentication protocols for low-cost RFID tags. The first protocol is based on dynamic identity and the second one on static identity. Both protocols have the merits of obtaining mutual authentication, protecting the user's privacy, and low computation cost. Furthermore, the proposed protocols can resist replay, impersonation, and de-synchronization attacks. © 2012 NSP Natural Sciences Publishing Cor.
Chen C.-C.,Wufeng University
Applied Soft Computing Journal | Year: 2011
In this article, a two-layer particle swarm optimization (TLPSO) is proposed to increase the diversity of the particles so that the drawback of trapping in a local optimum is avoided. In order to design the TLPSO, a structure with two layers (top layer and bottom layer) is proposed so that M swarms of particles and one swarm of particles are generated in the bottom layer and the top layer, respectively. Each global best position in each swarm of the bottom layer is set to be the position of the particle in the swarm of the top layer. Therefore, the global best position in the swarm of the top layer influences indirectly the particles of each swarm in the bottom layer so that the diversity of the particles increases to avoid trapping into a local optimum. Besides, a mutation operation is added into the particles of each swarm in the bottom layer so that the particles leap the local optimum to find the global optimum. Finally, some optimization problems of different types of high dimensional functions are used to illustrate the efficiency of the proposed method. © 2010 Elsevier B.V. All rights reserved.
Chi M.,Wufeng University
Construction and Building Materials | Year: 2012
This study presents an investigation into physical and mechanical properties and durability of alkali-activated slag concrete (AASC). Sodium oxide (Na 2O) concentrations of 4%, 5% and 6% of slag weight and liquid sodium silicate with modulus ratio (mass ratio of SiO 2 to Na 2O) of 0.8 were used as alkaline activators to activate granulated blast furnace slag (GBFS). Specimens with/without phosphoric acid (H 3PO 4) were cast and cured in the air, under the saturated limewater and in a curing room at relative humidity of 80% RH and temperature of 60°C, respectively. Their performance was discussed and compared with reference concretes produced using ordinary Portland cement concrete (OPC). Test results show that both the dosage of Na 2O and H 3PO 4 of additional mixture are significant factors influencing the properties of the fresh AASC mixtures. In hardened concrete, better properties and durability, such as compressive strength, splitting tensile strength, drying shrinkage, total charge passed, high-temperature resistance and sulphate attack resistance, have been obtained in AASC than comparable OPC. The properties and durability of AASC were significantly dependent on dosage of Na 2O and curing conditions. The properties and durability of AASC improved with an increase dosage of Na 2O and AASC cured at relative humidity of 80% RH and temperature of 60°C has the superior performance, followed the AASC by air curing and saturated limewater curing based on the presented observations and results. © 2012 Elsevier Ltd. All rights reserved.
Chi J.-H.,Wufeng University
Journal of Forensic Sciences | Year: 2013
An inn fire occurring in the middle of the night usually causes a great deal more injuries and deaths. This article examines the case study of an inn fire accident that resulted in the most serious casualties in Taiwan's history. Data based on the official fire investigation report and NFPA921 regulations are used, and the fire scenes are reconstructed using the latest Fire Dynamics Simulator (FDS) program from NIST. The personnel evacuation time and time variants for various fire hazard factors of reconstructive analysis clarify the reason for such a high number of casualties. It reveals that the FDS program has come to play an essential role in fire investigation. The close comparison between simulation result and the actual fire scene also provides fire prevention engineers, a possible utilization of FDS to examine the effects of improved schemes for fire safety of buildings. © 2012 American Academy of Forensic Sciences.