Ming-Hseng Tseng

Computation of three-dimensional flow around square and circular piers

The aim of the present study is to investigate, by numerical simulation, the three-dimensional turbulent flow field around square and circular piers. The numerical model employs a finite volume method based on MacCormacks explicit predictor–corrector scheme to solve weakly compressible hydrodynamic equations for turbulent flow. Computed results are compared with Dargahis experimental measurements to assess the validity of the proposed model. Very good agreements are obtained. The results of flow simulation indicate that near the upstream face of the pier there exists a downflow, which joins the separated flow to form the horseshoe vortex stretched around the pier. This horseshoe vortex interacts with the wake vortex to create the upflow behind the pier. These phenomena appear to be very important to the mechanism of scouring around the pier. In general, the flow patterns for the square and circular piers are similar. However, the strengths of the downflow and horseshoe vortex are greater in the case of the square pier. The position of the horseshoe vortex around the circular pier is closer to the front face than that around the square pier. In the meantime, the domain of the wake flow in the case of the square pier is greater than that in the case of the circular one. Copyright

Adaptive directed mutation for real-coded genetic algorithms

Adaptive directed mutation (ADM) operator, a novel, simple, and efficient real-coded genetic algorithm (RCGA) is proposed and then employed to solve complex function optimization problems. The suggested ADM operator enhances the abilities of GAs in searching global optima as well as in speeding convergence by integrating the local directional search strategy and the adaptive random search strategies. Using 41 benchmark global optimization test functions, the performance of the new algorithm is compared with five conventional mutation operators and then with six genetic algorithms (GAs) reported in literature. Results indicate that the proposed ADM-RCGA is fast, accurate, and reliable, and outperforms all the other GAs considered in the present study.

Explicit finite volume non-oscillatory schemes for 2D transient free-surface flows

A class of high-resolution non-oscillatory shock-capturing Roe, TVD and ENO explicit schemes in finite volume approach are presented for the computation of 2D unsteady rapidly varied open channel flows. In order to apply these schemes to simulate the hydraulic phenomena in field, the Strang-type operator splitting technique is adopted to treat the flow with bottom slope and friction terms. Verifications of the proposed schemes are made by comparison with analytical solutions or experimental data, and very good agreements are obtained. To illustrate the efficiency and stability of the present algorithms, four typical problems of rapidly varied flows are solved and the results of different schemes are compared. It is demonstrated that the proposed method is accurate, robust and highly stable even in the flows with very strong discontinuites, which need no tuning of any adjustable parameter, such as artificial viscosity coefficient, as other methods do, and is a reliable mathematical modeling for 2D practical hydraulic engineering applications. Copyright

Medical data mining using BGA and RGA for weighting of features in fuzzy k-NN classification

The k-nearest neighbor (k-NN) algorithm is commonly used in applications of classifiers and data mining and the related area due to its simplicity and effectiveness. In this study, all of features and optimal feature subsets with three features are investigated. For classification, crisp k-NN, fuzzy k-NN, and weighting fuzzy k-NN classifiers are compared. For weighting of features, two types of coding including binary-coded genetic algorithms (BGA) and real-coded genetic algorithms (BGA) are evaluated. Experiments are conducted on the Wisconsin diagnosis breast cancer (WDBC) dataset and the Pima (PIMA) Indians diabetes dataset, and the classification accuracy, false negative, and computation time are reported in this paper.

The genetic algorithm for breast tumor diagnosis-The case of DNA viruses

The purpose of this study is to determine the bioinformatics between breast tumors and DNA viruses. To extract significant factors for breast tumors, two methods - analysis of variance (ANOVA) and information measurement - are used; then, the results show that human papillomavirus (HPV) is not significant factor. Further, genetic algorithm (GA)-based data mining was submitted to obtain the rule between other DNA viruses and breast cancer/fibroadenoma. The GA rule shows that the effect of breast cancer includes {herpes simplex virus (HSV)-1 (-), human herpesvirus (HHV)-8 (-,+)}, {HSV-1(-)}, or {HHV-8(-)}, and that the effect of fibroadenoma includes {HSV-1(+), HHV-8(+)}, {HSV-1(+)}, or {HHV-8(+)}. Furthermore, the Mantel-Haenszel test shows that GA rules make a distinction between breast cancer and fibroadenoma. Finally, regarding diagnosis cost and accuracy, this study suggests that considering HSV-1 alone or with HHV-8 is optimal, but considering only HHV-8 yields less accurate results.

Comparison of regression models, grey models, and supervised learning models for forecasting flood stage caused by typhoon events

Abstract In this paper, four simple dynamic prediction methods and two supervised learning techniques including a linear regression model, a quadratic regression model, an original grey prediction model, a modified grey prediction model, a back‐propagation neural network model, and an epsilon‐SVM regression model were investigated for the forecasting of flood stage one hour ahead for early warning of flooding hazards. Quantitative evaluations were carried out between the predicted values by using the six forecasting models and the measured values obtained in the field. The comparisons confirm the ability of the simple grey prediction model to forecast flood stage by using only three observations of water stage with reasonable accuracy for the study cases, especially for study areas with scanty hydrological data.

A study on cluster validity using intelligent evolutionary K-means approach

The K-means clustering is commonly used in applications of unsupervised classification and the related area due to its simplicity and effectiveness. In this study, an intelligent evolutionary K-means algorithm (IEKA) is firstly developed to optimize the cluster centers by using an improved real-coded genetic algorithm. Then, four cluster validation indices for data clustering are evaluated on six real-life datasets. Finally, experiments are conducted and the performance comparisons of the proposed IEKA approach with other six clustering techniques are reported in this paper.

The Geographic Accessibility and Inequality of Community-Based Elderly Learning Resources: A Remodeling Assessment, 2009-2017.

ABSTRACT Continuous elderly learning activities not only empower elderly populations’ knowledge about health but also enhance these populations’ social connections and social abilities, which can enhance their overall quality of life. Geographic accessibility is a determinant factor for elderly participation in social activities. In this study, we proposed six measurement methods and employed the Gini coefficient to discuss the geographic accessibility and geographic inequality of community-based elderly learning resources. This study provides three methodological contributions for future research. First, we propose an origin–destination cost matrix analysis that incorporates a post-pruning technique. Applying this technique allows for the consideration of policy restrictions in relation to resource utilization. This approach also contributes to the ability to obtain a reliable assessment of the accessibility of resources. Second, this study proposes a new, more direct and convenient, method of calculating the Gini coefficient. Third, we find that the different distance-decay index β indicates the impact of distance factors on the efficiency of resource utilization. The distance-decay index β should carefully discern when distance is under 1 km. These results indicate that assessing accessibility does not only consider length and traffic distance but also requires a deliberate and weighted calculating process depending on the distance, elderly demand population, and supply capacities of learning centers. Although our study focuses on Taiwanese cases, our methodologies and results illustrate possibilities for other contributions that assess geographic accessibility and resource-allocation inequality for elderly learning policy planning and implementation.

Favorable clinical outcome of nonalcoholic liver cirrhosis patients with coronary artery disease: A population-based study

AIM To elucidate the prevalence and risk of mortality of nonalcoholic liver cirrhosis (LC) patients with coronary artery disease (CAD). METHODS The study cohort included newly diagnosed nonalcoholic LC patients age ≥ 40 years old without a diagnosis of CAD from 2006 until 2011 from a longitudinal health insurance database. The mean follow-up period for the study cohort was 1152 ± 633 d. The control cohort was matched by sex, age, residence, and index date. Hazard ratios (HRs) were calculated using the Cox proportional hazard model and the Kaplan-Meier method. RESULTS After exclusion, a total of 3409 newly diagnosed nonalcoholic cirrhotic patients were identified from one million samples from the health insurance database. We found that CAD (5.1% vs 17.4%) and hyperlipidemia (20.6% vs 24.1%) were less prevalent in nonalcoholic LC patients than in normal subjects (all P < 0.001), whereas other comorbidities exhibited an increased prevalence. Among the comorbidities, chronic kidney disease exhibited the highest risk for mortality (adjusted HR (AHR) = 1.76; 95%CI: 1.55-2.00, P < 0.001). Ascites or peritonitis exhibited the highest risk of mortality among nonalcoholic cirrhotic patients (AHR = 2.34; 95%CI: 2.06-2.65, P < 0.001). Finally, a total of 170 patients developed CAD after a diagnosis of nonalcoholic LC. The AHR of CAD in nonalcoholic LC patients was 0.56 (95%CI: 0.43-0.74, P < 0.001). The six-year survival rates for nonalcoholic LC patients with and without CAD were 52% and 50%, respectively (P = 0.012). CONCLUSION We conclude that CAD was less prevalent and associated with a reduced risk of mortality in nonalcoholic cirrhotic patients.

Major bleeding events after endoscopic sphincterotomy and endoscopic papillary balloon dilatation in cirrhotic patients: A nationwide population-based cohort study

Endoscopic sphincterotomy (EST) or endoscopic papillary balloon dilatation (EPBD) were two important methods for therapeutic endoscopic retrograde cholangiopancreatography (ERCP). Post‐ERCP bleeding is a troublesome issue especially in patients with bleeding tendency, like cirrhotic patients. In viewing the need of a safer method, we thus aimed to evaluate the post‐EST or post‐EPBD bleeding rate among cirrhotic patients based on Taiwans National Health Insurance Research Database (NHIRD).