Improvement of the Damaged Thermowell of the Monju Fast-Breeder Reactor Based on Vibration Analysis
In December 1995, the thermowell in the secondary cooling system of the Japanese fast-breeder reactor Monju was damaged, resulting in a sodium leak. Sodium flow was thought to have produced a vibration in the thermowell that then caused high-cycle fatigue that eventually destroyed the thermowell. Using the finite element method, the natural frequency of the thermowell was found to be approximately 230 Hz, which is in the region of resonance of the fluid vibration. Next, in a theoretical study, the authors altered the position at which the diameter of the thermowell changes and examined the resulting natural frequencies. They also studied the effects of thickness and diameter on the natural frequency of the thermowell and examined the case for a truncated conical thermowell. The results indicate that production of a thermowell that is not affected by vibration due to resonance is possible. This paper recommends improved shapes for the thermowell.

title: Design of a real-time interactive tele-exercise classroom for computer exercises over a Gigabit Network
abstract: This paper proposes a tele-exercise classroom for computer exercises over the Japan Gigabit Network. The requirements for constructing the tele-exercise classroom be discussed. The main features of the classroom are (1) a teacher can monitor a strident's operations, (2) give instructions to the student, (3) show a demonstration to the student. Besides, exercise materials and/or problems happening during the exercise class can be presented by using a synchronous/asynchronous white board, and discussions between the teacher and a student (students) can be carried out through interactive real-time video/audio. We present a systems model which shows the configuration of the system, user computer terminal types, system modes, and action modes. In addition, the extendibility of the system is considered in the model.

title: On spanning trees and walks of low maximum degree

title: Tibetan Language Continuous Speech Recognition Based on Dynamic Bayesian Network
abstract: Dynamic Bayesian Networks (DBN) area subset of the probabilistic graphical models (PGM) which include hidden Markov model (HMM) as a special case. One of the principle weaknesses of HMMs is the independence assumptions on the observed and hidden processes of speech. This paper proposed to use the DBN for Tibetan language continuous speech recognition.The proposed approach is based on structure learning paradigm in DBN framework. This approach has the advantage to guaranty that the resulting model represents speech with higher fidelity than HMM. The results of recognition experiments show that the proposed algorithm has better performance of recognition rate and noise suppression compared with HMM.

title: 3-Coloring graphs embedded in surfaces
abstract: In this article, we show that there exists an integer k(Σ) ≥ 5 such that, if G is a graph embedded in a surface Σ without i-circuits, 4 ≤ i ≤ k(Σ), then G is 3-colorable.

title: Silicon Wafer Defect Extraction Based on Morphological Filter and Watershed Algorithm
abstract: Defect extraction techniques are studied regarding the silicon wafer surface defect. We design a new filter based on multiple structuring elements and suggest an improved marker-based and region merging watershed. To begin with, the filter which generalized close-opening and open-closing filter based on the morphological filter with multiple structuring elements is introduced to eliminate the noise and simplify the image and morphological gradient image while preserving the details. And then in order to reduce the over-segmentation of the watershed algorithm, this paper suggests an improved marker-based and region merging method, region average gray value and edge strength criterion is used in merging operation and has a good effect on segmentation. Finally, the improved watershed algorithm is applied to the filtered gradient image to get the defect contours. The experiments show that this method can eliminate the noises and extract accurately location and closed region contours, which lays a good foundation for defect feature extraction and selection.

title: On 2-Connected Spanning Subgraphs with Low Maximum Degree
abstract: Given a graphG, let ak-trestle ofGbe a 2-connected spanning subgraph ofGof maximum degree at mostk. Also, let?(G) be the Euler characteristic ofG. This paper shows that every 3-connected graphGhas a (10?2?(G))-trestle. If?(G)??5, this is improved to 8?2?(G), and for?(G)??10, this is further improved to 6?2?(G). This result is shown to be best possible for almost all values of?(G) by the demonstration of 3-connected graphs embedded on each surface of Euler characteristic??0 which have no (5?2?)-trestle. Also, it is shown that a 4-connected graph embeddable on a surface with non-negative Euler characteristic has a 3-trestle, approaching a conjecture of Nash-Williams.