Data Mining - Concepts and Techniques.

(1990). ENERGY FUNCTION ANALYSIS FOR POWER SYSTEM STABILITY. Electric Machines & Power Systems: Vol. 18, No. 2, pp. 209-210.

Energy function analysis for power system stability

This paper surveys expert systems (ES) development using a literature review and classification of articles from 1995 to 2004 with a keyword index and article abstract in order to explore how ES methodologies and applications have developed during this period. Based on the scope of 166 articles from 78 academic journals (retrieved from five online database) of ES applications, this paper surveys and classifies ES methodologies using the following eleven categories: rule-based systems, knowledge-based systems, neural networks, fuzzy ESs, object-oriented methodology, case-based reasoning, system architecture, intelligent agent systems, database methodology, modeling, and ontology together with their applications for different research and problem domains. Discussion is presented, indicating the followings future development directions for ES methodologies and applications: (1) ES methodologies are tending to develop towards expertise orientation and ES applications development is a problem-oriented domain. (2) It is suggested that different social science methodologies, such as psychology, cognitive science, and human behavior could implement ES as another kind of methodology. (3) The ability to continually change and obtain new understanding is the driving power of ES methodologies, and should be the ES application of future works.

http://www.sci.brooklyn.cuny.edu/~kopec/cis718/fall_2005/sdarticle5.pdf

Expert system methodologies and applications—a decade review from 1995 to 2004

Dynamic analysis of flexible manipulators, a literature review

Vibration-assisted machining (VAM) combines precision machining with small-amplitude tool vibration to improve the fabrication process. It has been applied to a number of processes from turning to drilling to grinding [9] , [36] . The emphasis on this literature review is the turning process where VAM has been applied to difficult applications such as diamond turning of ferrous and brittle materials, creating microstructures with complex geometries for products like molds and optical elements, or economically producing precision macro-scale components in hard alloys such as Inconel or titanium. This review paper presents the basic kinematic relationships for 1D (linear vibratory tool path) and 2D VAM (circular/elliptical tool path). Typical hardware systems used to achieve these vibratory motions are described. The periodic separation between the tool rake face and uncut material, characteristic of VAM, is related to observed reductions in machining forces and chip thickness, with distinct explanations offered for 1D and 2D modes. The reduced tool forces in turn are related to improvements in surface finish and extended tool life. Additional consideration is given to the intermittent cutting mechanism and how it reduces the effect of thermo-chemical mechanisms believed responsible for rapid wear of diamond tools when machining ferrous materials. The ability of VAM to machine brittle materials in the ductile regime at increased depth of cut is also described.

Review of vibration-assisted machining

This paper presents a new algorithm for reactive-power optimization of large-scale power systems involving both discrete and continuous variables. This algorithm realizes successive discretization of the discrete control variables in the optimization process by incorporating a penalty function into the nonlinear primal-dual interior-point algorithm. The principle of handling these discrete variables by the penalty function, the timing of introducing the penalty function during iterations, and the setting of penalty factors are discussed in detail. To solve the high-dimension linear correction equation speedily and efficiently in each iteration, a novel data structure rearrangement is proposed. Compared with the existing data structures, it can effectively reduce the number of nonzero fill-in elements and does not give rise to difficulty in triangular factorization. The numerical results of test systems that range in size from 14 to 538 buses have shown that the proposed method can give nearly optimum solutions, has good convergence, and is suitable for large-scale system applications.

An extended nonlinear primal-dual interior-point algorithm for reactive-power optimization of large-scale power systems with discrete control variables

X-ray-based inspection systems are a well-accepted technique for identification and evaluation of internal defects in castings, such as cracks, porosities, and foreign inclusions. In this paper, some images showing typical internal defects in the castings derived from an X-ray inspection system are processed by some traditional methods and wavelet technique in order to facilitate automatic detection of these internal defects. An X-ray inspection system used to detect the internal defects of castings and the typical internal casting defects is first addressed. Second, the second-order derivative and morphology operations, the row-by-row adaptive thresholding, and the two-dimensional (2-D) wavelet transform methods are described as potentially useful processing techniques. The first method can effectively detect air-holes and foreign-inclusion defects, and the second one can be suitable for detecting shrinkage cavities. Wavelet techniques, however, can effectively detect the three typical defects with a selected wavelet base and multiresolution levels. Results indicate that 2-D wavelet transform is a powerful method to analyze images derived from X-ray inspection for automatically detecting typical internal defects in the casting

Improving Automatic Detection of Defects in Castings by Applying Wavelet Technique

A PZT actuator control of a single-link flexible manipulator based on linear velocity feedback and actuator placement

This paper proposes a wavelet-based extended fuzzy reasoning approach to power-quality disturbance recognition and identification. To extract power-quality disturbance features, the energy distribution of the wavelet part at each decomposition level is introduced and its calculation mathematically established. Based on these features, rule bases are generated for extended fuzzy reasoning. The power-quality disturbance features are finally mapped into a real number, in terms of which different power-quality disturbance waveforms are classified. Numerical results obtained from a large database show that the disturbance waveforms such as high- and low-frequency capacitor switching, voltage sag, impulsive transient, transformer energizing, and perfect sine waveform can all be correctly identified. The effect of the amplitude and frequency content of power-quality disturbance on the energy distribution patterns and the effect of noise on classification accuracy are also discussed in the paper.

Wavelet-based fuzzy reasoning approach to power-quality disturbance recognition

Wavelet transforms and fuzzy techniques are used to monitor tool breakage and wear conditions in real time according to the measured spindle and feed motor currents, respectively. First, continuous and discrete wavelet transforms are used to decompose the spindle and feed ac servo motor current signals to extract signal features so as to detect the breakage of drills successfully. Next, the models of the relationships between the current signals and the cutting parameters are established under different tool wear states. Subsequently, fuzzy classification methods are used to detect tool wear states based on the above models. Finally, the two methods above are integrated to establish an intelligent tool condition monitoring system for drilling operations. The monitoring system can detect tool breakage and tool wear conditions using very simple current sensors. Experimental results show that the proposed system can reliably detect tool conditions in drilling operations in real time and is viable for industrial applications.

/pdf/real-time-tool-condition-monitoring-using-wavelet-transforms-5em7zcunbx.pdf

Shiu Kit Tso

Papers

An extended nonlinear primal-dual interior-point algorithm for reactive-power optimization of large-scale power systems with discrete control variables

Improving Automatic Detection of Defects in Castings by Applying Wavelet Technique

A PZT actuator control of a single-link flexible manipulator based on linear velocity feedback and actuator placement

Wavelet-based fuzzy reasoning approach to power-quality disturbance recognition

Real-time tool condition monitoring using wavelet transforms and fuzzy techniques