Practical Reliability and Maintainability Analysis Tool for an Open Source Cloud Computing

We focus on a cloud computing environment by using open source softwares such as OpenStack and Eucalyptus because of the unification management of data and low cost. A cloud computing is attracting attention as a network service to share the computing resources, that is, networks, servers, storage, applications, and services. We propose jump diffusion models based on stochastic differential equations in order to consider the interesting aspect of the provisioning process. Especially, the reliability and maintainability analysis tool for cloud computing is developed in this paper. Also, we analyze actual data to show numerical illustrations of application of the software analysis tool considering the characteristics of cloud computing. Copyright © 2015 John Wiley & Sons, Ltd.     

Mechanical property enhancement of aligned multi-walled carbon nanotube sheets and composites through press-drawing process

A solid-state drawing and winding process was done to create thin aligned carbon nanotube (CNT) sheets from CNT arrays. However, waviness and poor packing of CNTs in the sheets are two main weaknesses restricting their reinforcing efficiency in composites. This report proposes a simple press-drawing technique to reduce wavy CNTs and to enhance dense packing of CNTs in the sheets. Non-pressed and pressed CNT/epoxy composites were developed using prepreg processing with a vacuum-assisted system. Effects of pressing on the mechanical properties of the aligned CNT sheets and CNT/epoxy composites were examined. Pressing with distributed loads of 147, 221, and 294 N/m showed a substantial increase in the tensile strength and the elastic modulus of the aligned CNT sheets and their composites. The CNT sheets under a press load of 221 N/m exhibited the best mechanical properties found in this study. With a press load of 221 N/m, the pressed CNT sheet and its composite, respectively, enhanced the tensile strength by 139.1 and 141.9%, and the elastic modulus by 489 and 77.6% when compared with non-pressed ones. The pressed CNT/epoxy composites achieved high tensile strength (526.2 MPa) and elastic modulus (100.2 GPa). Results show that press-drawing is an important step to produce superior CNT sheets for development of high-performance CNT composites.     

Thermal conductivity and phonon scattering mechanisms in La#x2212;x#x2212;x#x2212;xMxCuO4

The thermal conductivity of high density La_2–xM_xCuO₄ (M=Ba, Sr) sintered materials was measured between 15K and 150K for the various concentrations of Ba and the phonon thermal conductivity was analyzed comparing with that of Nd_2–xCe_xCuO₄. The pretty large value for pure La₂CuO₄ was drastically diminished by substituting La by a small amount of Ba atoms especially at low temperatures. It was found that a new type of the phonon scattering center such as a two-level tunneling must be taken account of in order to explain the observed reduction.     

Constant-phase-mode operation of the light-addressable potentiometric sensor

The constant-phase-mode operation of the light-addressable potentiometric sensor (LAPS) is proposed and demonstrated. In this new operation mode, the temporal change and the spatial distribution of the analyte concentration are recorded in the form of the bias voltage applied to the LAPS sensor plate, which is servo-controlled to maintain the phase of the photocurrent at a constant value with respect to the light modulation. The constant-phase-mode LAPS is advantageous for its wider measurement range and reduction of artifacts.     

Submodular fractional programming for balanced clustering

We address the balanced clustering problem where cluster sizes are regularized with submodular functions. The objective function for balanced clustering is a submodular fractional function, i.e., the ratio of two submodular functions, and thus includes the well-known ratio cuts as special cases. In this paper, we present a novel algorithm for minimizing this objective function (submodular fractional programming) using recent submodular optimization techniques. The main idea is to utilize an algorithm to minimize the difference of two submodular functions, combined with the discrete Newton method. Thus, it can be applied to the objective function involving any submodular functions in both the numerator and the denominator, which enables us to design flexible clustering setups. We also give theoretical analysis on the algorithm, and evaluate the performance through comparative experiments with conventional algorithms by artificial and real datasets.     

Water-retaining ability of diacylglycerol

The water-in-oil emulsification characteristics and the adsorption properties of DAG at the oil/water interface were investigated for DAG having different FA compositions. The water-retaining ability of DAG is dependent on the FA composition but is not dependent on the interfacial tension at the oil/water interface in a simple way. The water-retaining ability is very different between uni-chain DAG (two FA have the same chain length) and complex-chain DAG (one FA is oleic acid and the other has a shorter alkyl chain). Uni-chain DAG, having long FA chains (R=C₁₂ or C_18∶1) have the ability to emulsify water at the volume fraction of 80% (ϕ80%), but uni-chain DAG with short or medium chain-length FA (R=C₃, C₄, C₆, C₈) show little ability to retain water. For complex-chain DAG, all the DAG studied here (R₁=C_18∶1, R₂=C₂−C₁₂) have the ability to emulsify water at ϕ80%. The stability of the emulsions, however, varies with the chain length of the R₂ FA (R₂ stability order: C₂, C₃>C_18∶1, C₁₀>C₈>C₄, C₆). The relationship between the water-retaining ability and the molecular structure of DAG is discussed from the viewpoint of intra- and intermolecular interactions between the FA chains.     

高性能粉末冶金材料与其制造工艺的开发

随着常规粉末冶金产业发展，像锻轧粉末冶金铝合金、超塑性高温合金、机械合金化氧化物弥散强化（ODS）合金之类的先进粉末冶金工艺，引起了人们的注意。受先进粉末冶金工艺启发，开发了适应日本汽车与家电产业的新材料与生产工艺，开发了适合于钢铁结构的粉末冶金Al-Si-X合金。为了改进经济性与近终形（NNS）成形性，开发了无包套粉末挤压工艺与精压式粉末锻造工艺。基于这些工艺，还开发了比单一结构材料具有较多功能的新材料，诸如轻量散热器（heat sink）与高性能发动机气缸内衬。     

Grain Boundary Segregation Behavior of Boron in Low-Alloy Steel

The boron concentration profiles around prior austenite grain boundaries in Fe-0.05C-0.5Mo-0.001B (mass pct) are examined using aberration-corrected STEM-EELS. In order to obtain the precise distribution of boron around the boundaries, tilt series measurements with thin specimens (<30 nm) are performed and the EEL spectra are analyzed by principal component analysis (PCA) and multivariate curve resolution (MCR). The boron concentration profile changes with the cooling rate from the solid solution temperature. The concentration at grain boundaries is maximized at a medium rate (30 °C/s), where the concentration reaches 8 at. pct, and it decreases at a larger (250 °C/s) or smaller (5 °C/s) rate. On the other hand, the boron distribution becomes wider as the cooling rate becomes smaller. The current results suggest that the boron segregation in the alloy is formed by the “non-equilibrium segregation mechanism.”     

Reversible Reaction with CO2 and Control of CO2 Absorption/Desorption Properties of Ba2(Fe1−xInx)2O5 Solid Solutions

Ba₂(Fe_1?xIn_x)₂O₅ was prepared by a solid‐state reaction under a N₂ flow. It was revealed that the solid solutions had a cubic perovskite structure with disordered oxygen vacancies at room temperature. Thermogravimetry and X‐ray diffraction measurements revealed that Ba₂(Fe_1?xIn_x)₂O₅ can reversibly react with CO_2. It was found that the equilibrium temperature of the reaction could be controlled by preparing solid solution.     

Numerical simulation of cavitation surge and vortical flows in a diffuser with swirling flow

The strong swirling flow at the exit of the runner of a Francis turbine at part load causes flow instabilities and cavitation surges in the draft tube, deteriorating the performance of the hydraulic power system. The unsteady cavitating turbulent flow in the draft tube is simplified and modeled by a diffuser with swirling flow using the Scale-adaptive simulation method. Unsteady characteristics of the vortex rope structure and the underlying mechanisms for the interactions between the cavitation and the vortices are both revealed. The generation and evolution of the vortex rope structures are demonstrated with the help of the iso-surfaces of the vapor volume fraction and the Qcriterion. Analysis based on the vorticity transport equation suggests that the vortex dilatation term is much larger along the cavity interface in the diffuser inlet and modifies the vorticity field in regions with high density and pressure gradients. The present work is validated by comparing two types of cavitation surges observed experimentally in the literature with further interpretations based on simulations.