Thao Nguyen-Trang

An effective reliability-based improved constrained differential evolution for reliability-based design optimization of truss structures

ICDE is extended to the RBDO problem of truss structures by combining ICDE with SORA which gives a so-called the SORA-ICDE.In SORA-ICDE, the optimization loop and reliability assessment loop are decoupled, and hence the efficiency in solving RBDO problems is ensured and improved significantly.Numerical results for five benchmark problems illustrate the effectiveness of the SORA-ICDE in solving the RBDO problem of truss structures. Recently, a Sequential Optimization and Reliability Assessment (SORA) method was proposed and proven to be effective for solving reliability-based design optimization (RBDO) problems. In the SORA, the optimization loop and the reliability assessment loop are decoupled from each other. This helps improve the efficiency of the SORA significantly. However, the SORA still exists two main drawbacks: (1) the optimal solutions are easily trapped within local extremes and (2) the optimal results depend on the initial trial points. To overcome these drawbacks, this paper integrates the SORA with the Improved Constrained Differential Evolution algorithm (ICDE) to give a so-called SORA-ICDE for solving RBDO problems. Due to the global search mechanism, the SORA-ICDE can easily obtain global solutions regardless of initial points. The numerical results obtained in the paper are compared with available results in the literature to illustrate the efficiency, applicability and precision of the SORA-ICDE in solving the RBDO problems for truss structures.

Fuzzy clustering of probability density functions

ABSTRACT Basing on L1-distance and representing element of cluster, the article proposes new three algorithms in Fuzzy Clustering of probability density Functions (FCF). They are hierarchical approach, non-hierarchical approach and the algorithm to determine the optimal number of clusters and the initial partition matrix to improve the qualities of established clusters in non-hierarchical approach. With proposed algorithms, FCF has more advantageous than Non-fuzzy Clustering of probability density Functions. These algorithms are applied for recognizing images from Texture and Corel database and practical problem about studying and training marks of students at an university. Many Matlab programs are established for computation in proposed algorithms. These programs are not only used to compute effectively the numerical examples of this article but also to be applied for many different realistic problems.

Modified genetic algorithm-based clustering for probability density functions

ABSTRACT This article modifies two internal validity measures and applies them to evaluate the quality of clustering for probability density functions (pdfs). Based on these measures, we propose a new modified genetic algorithm called GA-CDF to establish the suitable clusters for pdfs. The proposed algorithm is tested by four numerical examples including two synthetic data sets and two real data sets. These examples illustrate the superiority of proposed algorithm over some existing algorithms in evaluating the internal or external validity measures. It demonstrates the feasibility and applicability of the GA-CDF for practical problems in data mining.

An Improved Fuzzy Time Series Forecasting Model

This model is developed from the model of Abbasov and Mamedova (2003) in which the parameters are investigated by methods and algorithm to obtain the most suitable values for each data set. The experiments on Azerbaijan’s population, Vietnam’s population and Vietnam’s rice production demonstrate the feasibility and applicability of the proposed methods.

Clustering for Probability Density Functions by New k-Medoids Method

This paper proposes a novel and efficient clustering algorithm for probability density functions based on -medoids. Further, a scheme used for selecting the powerful initial medoids is suggested, which speeds up the computational time significantly. Also, a general proof for convergence of the proposed algorithm is presented. The effectiveness and feasibility of the proposed algorithm are verified and compared with various existing algorithms through both artificial and real datasets in terms of adjusted Rand index, computational time, and iteration number. The numerical results reveal an outstanding performance of the proposed algorithm as well as its potential applications in real life.

Similar Coefficient for Cluster of Probability Density Functions

ABSTRACT In this article, we propose a new criterion to evaluate the similarity of probability density functions (pdfs). We call this the criterion on similar coefficient of cluster (SCC) and use it as a tool to deal with overlap coefficients of pdfs in normal standard on [0;1]. With the support of the self-update algorithm for determining the suitable number of clusters, SCC then becomes a criterion to establish the corresponding cluster for pdfs. Moreover, some results on determination of SCC in case of two and more than two pdfs as well as relations of different SCCs and other measures are presented. The numerical examples in both synthetic data and real data are given not only to illustrate the suitability of proposed theories and algorithms but also to demonstrate the applicability and innovation of the proposed algorithm.

Factors Influencing the Intentions of Using Tax Consulting Services of Firms in Ho Chi Minh City: A Structural Equation Model

Tax consulting service is one of various professional consulting services and is interested to study by many researchers. Nevertheless, this issue has not been interested to research in Vietnam. This paper performs confirmatory factors analysis (CFA) and structural equation modeling (SEM) to identify the factors influencing the intentions of using tax consulting services of firms in Ho Chi Minh city, Vietnam. Specifically, this paper finds that the intentions depend on the “attitude toward the behavior” and “replacement”. In addition, through Chi-square test, it can be proven that the intentions also depend on type of firms and whether they have ever used tax consulting service or not. Based on the obtained results, the discussion and recommendation are also proposed. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.