Efficient Leave-<Emphasis Type="Italic">m</Emphasis>-out Cross-Validation of Support Vector Regression by Generalizing Decremental Algorithm

We propose a computationally efficient method for cross-validation of the Support Vector Regression (SVR) by generalizing the decremental algorithm of SVR. Incremental and decremental algorithm of Support Vector Machines (SVM) ^{2, 8, 9)} efficiently update the trained SVM model when a single data point is added to or removed from the training set. The computational cost of leave-one-out cross-validation can be reduced using the decremental algorithm. However, when we perform leave-m-out cross-validation (m > 1), we have to repeatedly apply the decremental algorithm for each data point. In this paper, we extend the decremental algorithm of SVR^{8, 9)} in such a way that several data points can be removed more efficiently. Experimental results indicate that the proposed approach can reduce the computational cost. In particular, we observed that the number of breakpoints, which is the main computational cost of the involved path-following, were reduced from \({\mathcal O}(m)\) to \({\mathcal O}(\sqrt{m})\).     

Molecular dynamics simulations of diffusion of submonolayer polar liquid lubricant films on solid surfaces

A fundamental understanding of the diffusion phenomena of submonolayer polar liquid films is important for achieving reliable lubrication between moving mechanical parts separated by a nanometer-sized gap. To acquire this understanding, we conducted molecular dynamics (MD) simulations of diffusion phenomena of submonolayer polar perfluoropolyether (PFPE) Zdol films on solid surfaces. To improve the accuracy of these simulations, we developed an all-atom model that includes hydrogen-bond potential and refined atomic charges for Zdol molecules and tested it through MD simulations of spreading of step-shaped submonolayer PFPE films. Our MD simulations reproduced the experimentally observed effects of polar end groups on the diffusion speed and molecular conformation of Zdol. We then conducted MD simulations of self-diffusion of submonolayer Zdol films; these simulations demonstrated that as the thickness of the submonolayer Zdol films decreases, molecular conformation becomes flatter and the self-diffusion coefficient decreases. These changes in molecular conformation partially explain our experimental finding that the spreading of step-shaped submonolayer polar PFPE films slows down with decreasing initial thickness.     

Accurate finite element method for atomic calculations based on density functional theory and Hartree–Fock method

An accurate finite element method is developed for atomic calculations based on density functional theory (DFT) within local density approximation (LDA) and Hartree–Fock (HF) method. The radial wave functions are expanded by cubic Hermite spline functions on a uniform mesh for , and all the associated integrals are analytically evaluated in conjunction with fitting procedures of the Hartree and the exchange–correlation potentials to the same cubic Hermite spline functions using a set of recurrence formulas. The total energy of atoms systematically converges from above, and the error algebraically decays as the mesh spacing decreases. When the mesh spacing d is taken to be , the total energy for an atom of atomic number Z can be calculated within error of ¹⁰−7 hartree for both the LDA and HF methods. The equal applicability of the method to DFT and the HF method with a similar degree of high accuracy enables the method to be a reliable platform for development of new functionals in DFT such as hybrid functionals.     

Accumulation of triosephosphate isomerase, with sequence homology to Beta amyloid peptides, in vessel walls of the newborn piglet hippocampus

We investigated whether beta-amyloid (Abeta)-like immunoreactivity was seen in the brains of newborn piglets. The immunoreactivity for Abeta(1-42) and Abeta(1-40) proteins, but not Abeta precursor protein, was present in CD68-positive perivascular cells of the hippocampus and in parts of the meninges. It was colocalized with immunoreactivity for receptor for advanced glycation end product and tumor necrosis factor-alpha. The protein with a molecular mass of 27 kDa, which was recognized by the Abeta antibodies, was identified as triosephosphate isomerase (TPI) with sequence homology to Abeta peptides by N-terminal amino acid sequencing, mass fingerprint analysis using matrix-associated laser desorption/ionization mass spectrometry, and Western blotting. Western blotting assay also revealed that detectable expression of Abeta proteins were not seen in the piglet brains. These findings indicate that TPI with sequence homology to Abeta peptides accumulates in perivascular cells of the microglia/macrophage lineage located around arterial vessels of the newborn piglet hippocampus.     

Using selective precipitant for uranyl ions — Fundamental studies for evaluating the precipitant performance

We have developed a simple reprocessing process for spent FBR fuels using N-cyclohexyl-2-pyrrolidone (NCP) which has selective precipitation ability for UO₂²⁺ ions. It was confirmed that NCP has sufficient precipitation ability for UO₂²⁺ ions, decontamination capability (separation of UO₂²⁺ from simulated fission products), and resistance to γ-ray radiation in nitric acid solutions. These findings indicate that NCP is applicable to our reprocessing process. We have also evaluated performances of other precipitants such as N-n-propyl-2-pyrrolidone (NProP), N-n-butyl-2-pyrrolidone (NBP), and N-n-butyl-2-pyridone (NBPyr). It was found that higher decontamination factors (DFs) are obtained by using NProP and NBP. This can be interpreted that the hydrophobicity of NProP and NBP is lower than that of NCP. Furthermore, we have obtained an experimental result that the resistance of NBPyr to γ-ray radiation is superior to that of NCP.     

A Knowledge Discovery System with Support for Model Selection and Visualization

The process of knowledge discovery in databases consists of several steps that are iterative and interactive. In each application, to go through this process the user has to exploit different algorithms and their settings that usually yield multiple models. Model selection, that is, the selection of appropriate models or algorithms to achieve such models, requires meta-knowledge of algorithm/model and model performance metrics. Therefore, model selection is usually a difficult task for the user. We believe that simplifying the process of model selection for the user is crucial to the success of real-life knowledge discovery activities. As opposed to most related work that aims to automate model selection, in our view model selection is a semiautomatic process, requiring an effective collaboration between the user and the discovery system. For such a collaboration, our solution is to give the user the ability to try various alternatives and to compare competing models quantitatively by performance metrics, and qualitatively by effective visualization. This paper presents our research on model selection and visualization in the development of a knowledge discovery system called D2MS. The paper addresses the motivation of model selection in knowledge discovery and related work, gives an overview of D2MS, and describes its solution to model selection and visualization. It then presents the usefulness of D2MS model selection in two case studies of discovering medical knowledge in hospital data—on meningitis and stomach cancer—using three data mining methods of decision trees, conceptual clustering, and rule induction.     

Stress distribution of coated film with a range of coated film thickness and elastic properties under a single EHL operating condition

In recent years, the techniques improving sliding performances have progressed by using coated films possessing superior tribological properties, to reduce the failures of the mechanical elements. Those techniques are often used under severe conditions such as elastohydrodynamic lubrication (EHL). In this paper, numerical three-dimensional analysis of the maximum shear stress applied into the coated film and substrate under a single EHL operating condition was performed with a range of coated film thickness and elastic properties. The strength of coated film as one of those techniques was evaluated numerically, resulting in an optimum design of coated film. As a result, coated films with a larger value of thickness and a smaller modulus of elasticity than that of substrate are preferable.     

Control of Oxidation State of Eu Ions in Na2O–Al2O3–SiO2 Glasses

Glasses doped with well‐controlled Eu³⁺ and Eu²⁺ ions have attracted considerable interest due to the possibility of tuning the wavelength range of the emitted light from violet to red by using their ⁵D₀→⁷F_j and 5d–4f electron transitions. Glasses were prepared to dope Eu³⁺ ions in a Na₂O–Al₂O₃–SiO₂ system, and the changes in the valence state of Eu³⁺ ions and the glass structure surrounding the Eu atoms during heating under H₂ atmosphere were investigated using fluorescence spectroscopy, X‐ray absorption fine‐structure spectroscopy, and ²⁷Al magic‐angle spinning solid‐state nuclear magnetic resonance spectroscopy. The reduction behavior of Eu³⁺ ions was dependent on the Al/Na molar ratio of the glass. For Al/Na < 1, the Al³⁺ ions formed the AlO₄ network structure accompanied by the Na⁺ ions as charge compensators; the Eu³⁺ ions occupied the interstitial positions in the SiO₄ network structure and were not reduced even under heating in H₂ gas. On the other hand, in the glasses containing Al₂O₃ with the Al/Na ratio exceeding unity, the Eu³⁺ ions commenced to be coordinated by the AlO₄ units in addition to the SiO₄ network structure. When heated in H₂ gas, H₂ gas molecules reacted with the AlO₄ units surrounding Eu³⁺ ions to form AlO₆ units terminated with OH bonds, and reduced Eu³⁺ ions to Eu²⁺ via the extracted electrons.     

Moisture profiles of wheat noodles containing hydroxypropylated tapioca starch

Wheat noodles were prepared using flour to which hydroxypropylated tapioca starch was added, and the effect of this addition on the moisture distribution within the noodles during cooking was examined using a digital image processing technique. The addition of the modified starch slightly increased the moisture content and narrowed the flat distribution near the noodle surface. The distribution features reflected the changes in the water absorption behaviour caused by the properties of the modified starch and the reduction in the gluten content. Addition of the modified starch lowered Young's modulus and the energy for 99% strain of the noodles in the texture analysis to, at maximum 35% and 65%, and decreased the breakability of the noodles. These changes in the moisture distribution and textural properties have been ascribed to changes in both the state of the starch granules near the surface and the structure of the gluten network.