Sirindhorn International Institute of Technology

About: Sirindhorn International Institute of Technology is a based out in . It is known for research contribution in the topics: Supply chain & Combustion. The organization has 1048 authors who have published 1678 publications receiving 30067 citations.

Numerical experiments with cooperating multiple quadratic snakes for road extraction

Abstract: Higher-order active contours or snakes show much promise for the extraction of complex objects from noisy imagery. These models provide an elegant mathematical framework for specifying the desired properties of target objects through energy functionals that can be minimized with standard optimization techniques. However, techniques to allow quadratic snakes to change topology during segmentation have not been fully exploited. Additionally, external forces for improving convergence of quadratic snakes have similarly yet to be explored. In this article, we propose a model that allows multiple quadratic snakes to split, merge, and disappear. Although the separate components of our approach have been introduced elsewhere by Cohen (1991), Xu and Prince (1997), and Rochery et al. (2006), this article is the first comprehensive empirical study of their performance on real-world complex network extraction tasks. We analyze the applicability of the model to road extraction from satellite images that vary in complexity from simple networks to large networks with multiple loops. We also analyze the effects of external forces enhanced by oriented filtering, gradient vector flow fields, and Canny edge detection. In a series of experiments, we found that the multiple cooperating quadratic snake model performs well on complex, noisy images. Our experiments also establish a performance improvement when the proposed quadratic model is coupled with the Canny-based gradient vector flow technique.

The Effects of Electro-Chemical Chloride Extraction on the Migration of Ions and the Corrosion State of Embedded Steel in Reinforced Concrete

Abstract: The effects of electrochemical chloride extraction were evaluated using different electrolytes and binders on cylindrical concrete specimens with a water/binder ratio of 0.4. Two-percent NaCl by weight of binder was added to the water as a chloride source during concrete casting. After the specimens were immersed in water for three months, direct current 0.5 A/m2 was applied to release approximately 30% initial chloride. The use of intermittent mode during extraction process was more efficient in releasing chloride than a continuous mode. After treatment, although the average remaining-chloride content was higher than threshold value, its content at the interface was only approximately 0.4%. The accumulation of alkaline ions around the embedded steel was noticeable but the distribution of calcium ions showed as different tendency. The migration of ions from the electrolyte was insignificant. This demonstrated the important role of internal ions in transferring the charge during extraction; simultaneously, the decomposition or transformation of hydrated products is inevitable. After the treatment was stopped for four weeks, the half-cell potential of the steel reached to low-corrosion state.

A Goal Programming Approach to Nurse Scheduling with Individual Preference Satisfaction

Abstract: The use of scheduling optimization tools is essential in creating an efficient nurse shift-rotation schedule. A well-designed nurse scheduling technique can improve nurses’ job satisfaction and their intention to stay. This study develops a goal programming approach to nurse scheduling that simultaneously considers workload fairness and individual preferences on working shift and day off assignments. A case study of an operating room at a hospital in Thailand is used to illustrate the model capabilities for solving an actual nurse scheduling problem. The job satisfaction factors defined based on an interview and questionnaire survey are integrated into the model. When compared against the manual scheduling result, the optimal schedules can be implemented to improve the nurse’s perception of fairness and preference satisfaction. The analysis of fairness and multiple individual preferences based on a case study investigation is the main contribution of this study.

Program generation in the equivalent transformation computation model using the squeeze method

Abstract: In the equivalent transformation (ET) computation model, a specification provides background knowledge in a problem domain, a program is a set of prioritized rewriting rules, and computation consists in successive reduction of problems by rule application. As long as meaning-preserving rewriting rules, called ET rules, with respect to given background knowledge are used, correct computation results are guaranteed. In this paper, a general framework for program synthesis in the ET model is described. The framework comprises two main phases: (1) equivalent transformation of specifications, and (2) generation of a program from an obtained specification. A method for program generation in the second phase, called the squeeze method, is presented. It constructs a program by accumulation of ET rules one by one on demand, with the goal of producing a correct, efficient, and nonredundant program.