Constraint graph-based frequent pattern updating from temporal databases

There have been many kinds of association rule mining (ARM) algorithms, e.g., Apriori and FP-tree, to discover meaningful frequent patterns from a large dataset. Particularly, it is more difficult for such ARM algorithms to be applied for temporal databases which are continuously changing over time. Such algorithms are generally based on repeating time-consuming tasks, e.g., scanning databases. To deal with this problem, in this paper, we propose a constraint graph-based method for maintaining frequent patterns (FP) discovered from the temporal databases. Particularly, the constraint graph, which is represented as a set of constraint between two items, can be established by temporal persistency of the patterns. It means that some patterns can be used to build the constraint graph, when the patterns have been shown in a set of the FP. Two types of constraints can be generated by users and adaptation. Based on our scheme, we find that a large number of dataset has been efficiently reduced during mining process and the gathering information while updating.     

Uniformly subsampled ensemble (USE) for churn management: Theory and implementation

The present paper explores the possible application of a new ensemble model. The model, which is based on multiple SVM classifiers, is employed to address churner identification problems in the mobile telecommunication industry, a sector in which the role of customer retention program becomes increasingly important due to its very competitive business environment. In particular, the current study introduces a uniformly subsampled ensemble (USE) model of SVM classifiers, not only to reduce the computational complexity of large-scale data, but also to boost the reliability and accuracy of calibrated models on data sets with highly skewed class distributions. According to our experiments, the performance of the USE SVM model is superior compared to all single and ensemble models. It is more scalable than well-known ensemble models as well.     

Parametric study on design of composite–foam–resin concrete sandwich structures for precision machine tool structures

In this paper, sandwich structures for micro-EDM machines are optimized by using parametric study varying composite geometries and parameters like stacking sequence, thickness and rib geometry. The structures are composed of fibre reinforced composites for skin material and resin concrete and PVC foam (Closed cell, Divinycell) for core materials. Column structure was designed by a beam with cruciform rib and performance indices such as static bending stiffness (EI) and specific bending stiffness (EI/ρ) for dynamic stability are examined by controlling the thickness and stacking sequence of composites. For the machine tool bed, which usually has a plate shape, was designed to have high stiffness in two directions at the same time controlling stacking sequence and rib geometry; that is, rib thickness and number of ribs. The sensitivity of design parameters like rib thickness and composite skin thickness was examined and the optimal condition for high stiffness structure was suggested. Finite element analysis was also performed to verify the static and dynamic robustness of the machine structure. L-shaped joint for combining bed and column of the micro-EDM machine was proposed and fabricated using adhesive bonding. The dynamic performance such as damping characteristics was investigated by vibration tests. From the results optimal configuration and materials for high precision micro-EDM machines are proposed.     

Material properties and growth control of undoped and Sn-doped In2O3 thin films prepared by using ion beam technologies

Undoped (IO) and Sn-doped In₂O₃ (ITO) films have been deposited on glass and polymer substrates by an advanced ion beam technologies including ion-assisted deposition (IAD), hybrid ion beam, ion beam sputter deposition (IBSD), and ion-assisted reaction (IAR). Physical and chemical properties of the oxide films and adhesion between films and substrates were improved significantly by these technologies. By using the IAD method, non-stoichiometry and microstructure of the films were controlled by changing assisted oxygen ion energy and arrival ratio of assisted oxygen ion to evaporated atoms. Relationships between structural and electrical properties in ITO films on glass substrates were intensively investigated by using the IBSD method with changing ion energy, reactive gas environment, and substrate temperature. Smooth-surface ITO films (R_rms ≤ 1 nm and R_p-v ≤ 10 nm) for organic light-emitting diodes were developed with a combination of deposition conditions with controlling microstructure of a seed layer on glass. IAR surface treatment enormously enhanced the adhesion of oxide films to polymer substrate. The different dependence of IO and ITO films' properties on the experimental parameters, such as ion energy and oxygen gas environment, will be intensively discussed.     

Phase evolution and dielectric properties of MgTi2O5 ceramic sintered with lithium borosilicate glass

Phase evolution, densification, and dielectric properties of MgTi₂O₅ dielectric ceramic, sintered with lithium borosilicate (LBS) glass, were studied. Reaction between LBS glass and MgTi₂O₅ was significant in forming secondary phases such as TiO₂ and (Mg,Ti)₂(BO₃)O. The glass addition was not necessarily deleterious to the dielectric properties due to the formation of TiO₂: permittivity increased and temperature coefficient of resonance frequency could be tuned to zero with the addition of LBS glass, although the inevitable glass-induced decrease of quality factor was not retarded by the formation of TiO₂. The sintered specimen with 10 wt% LBS fired at 950 °C for 2 h showed permittivity of 19.3, quality factor of 6800 GHz, and τ_f of −16 ppm/°C.     

Optimal decoder for block-transform based video coders

In this paper, we introduce a new decoding algorithm for DCT-based video encoders, such as Motion JPEG (M-JPEG), H26x, or MPEG. This algorithm considers not only the compression artifacts but also the ones due to transmission, acquisition or storage of the video. The novelty of our approach is to jointly tackle these two problems, using a variational approach. The resulting decoder is object-based, allowing independent and adaptive processing of objects and backgrounds, and considers available information provided by the bitstream, such as quantization steps, and motion vectors. Several experiments demonstrate the efficiency of the proposed method. Objective and subjective quality assessment methods are used to evaluate the improvement upon standard algorithms, such as the deblocking and deringing filters included in MPEG-4 postprocessing.     

Statistically representative three-dimensional microstructures based on orthogonal observation sections

Techniques are described that have been used to create a statistically representative three-dimensional model microstructure for input into computer simulations using the geometric and crystallographic observations from two orthogonal sections through an aluminum polycrystal. Orientation maps collected on the observation planes are used to characterize the sizes, shapes, and orientations of grains. Using a voxel-based tessellation technique, a microstructure is generated with grains whose size and shape are constructed to conform to those measured experimentally. Orientations are then overlaid on the grain structure such that distribution of grain orientations and the nearest-neighbor relationships, specified by the distribution of relative misorientations across grain boundaries, match the experimentally measured distributions. The techniques are applicable to polycrystalline materials with sufficiently compact grain shapes and can also be used to controllably generate a wide variety of hypothetical microstructures for initial states in computer simulations. This article is based on a presentation made at the symposium “Characterization and Representation of Material Microstructures in 3-D” held October 8–10, 2002, in Columbus, OH, under the auspices of ASM International’s Phase Transformations committee.     

Influence of calcination temperature on structural and optical properties of TiO2-SiO2 thin films prepared by sol-gel dip coating

We prepared TiO₂-SiO₂ thin films with various TiO₂/SiO₂ ratios by sol-gel dip coating method and explored the dependence of their structural and optical properties on calcination temperature. The absorption peaks relevant to Si—O, Si—O—Ti and Ti—O bonds appeared in the FTIR spectra. With increasing TiO₂ content, the intensity of Si—O bond peaks decreases and that of Ti—O bond peaks increases. The XRD results show that the temperature of transformation from amorphous to anatase phase is lowered as TiO₂ content increases. The crystallite size of anatase phase in composite thin films increases with increasing TiO₂ content and calcination temperature. At 1000°C, the mixed phase of anatase and rutile appears in the pure TiO₂ thin films. The rutile films are denser than the anatase films. The increase in refractive index of composite thin films with calcination temperature is related to the decreased thickness and increased density as a result of evaporation of water and organic matters below 400°C. On the other hand, it is related to the change in the crystal phase and crystallite size of the films over 400°C.     

Interfacial reactions and intermetallic compound growth between indium and copper

The growth kinetics of intermetallic compound layers formed between pure indium solder and bare Cu substrate by solid-state isothermal aging were examined at temperatures between 343 and 393 K for 0–4×10⁶ s. A quantitative analysis of the intermetallic compound layer thickness as a function of time and temperature was performed. Experimental results showed that the Cu₁₁In₉ intermetallic compound was observed for bare copper substrate. Additionally, the thickness of the Cu₁₁In₉ intermetallic compound was increased with the aging temperature and time. The layer growth of the intermetallic compound in the couple of the In/Cu system followed a parabolic law over the given temperature range. As a whole, because the values of time exponent (n) were approximately 0.5, the layer growth of the intermetallic compound was mainly controlled by a diffusion mechanism over the temperature range studied. The apparent activation energy of Cu₁₁In₉ intermetallic compound in the couple of the In/Cu was 34.16 kJ mol^–1.