Microstructure and mechanical properties of hot-pressed SiC-TiC composites

Hot-pressed SiC-TiC composite ceramics with 0–100 wt% TiC have been investigated to determine the effect of composition (amount of TiC) on the elastic modulus, hardness, flexural strength and fracture toughness,K _IC. The composites exhibited superior mechanical properties compared to monolithic SiC and TiC, especially in fracture toughness,K _IC, value for 30–50 wt% TiC composite. The maximum values ofK _IC and room-temperature flexural strength were 6 MPa m^1/2 for a 50 wt % TiC and 750 MPa for a 30 wt% TiC composite, respectively. The observed toughening could be attributed to the deflection of cracks due to dispersion of the different particles. Although no third phases were detected by both TEM and XRD studies, an EDAX study and resistivity measurements indicated some possibility of solid solutions being present. The composites containing more than 30 wt% TiC, exhibited resistivity lower than 10^–3 cm which is favourable for electro-discharge machining of ceramics.     

Multi‐primary‐color LCD: Its characteristics and extended applications

Abstract— The development of multi‐primary‐color (MPC) display systems is one of the big paradigm shifts in recent display technologies and induces new potentials of display devices. The development of MPC display systems for different goals is briefly reviewed. Especially, by employing MPC systems, it is possible to reproduce the real material colors faithfully and efficiently. For signal processing, MPC systems have a big advantage in the so‐called color‐reproduction redundancy. A number of applications can be derived from this characteristic, such as improving the viewing‐angle dependency issue and power savings. On the other hand, MPC systems have a typical trade‐off versus RGB‐standardized input signals, especially for reproducing bright green. New algorithms to moderate this trade‐off on MPC systems by employing color‐reproduction redundancy are proposed. The goal of our algorithms is to maintain the compatibility with RGB‐based input signals though the initial display design so that the characteristics of MPC systems are not changed or lost. These algorithms indicate that MPC display systems are applicable not only for a specifically limited objective but also for other applications, e.g., TV broadcasting.     

Performance of the improved version of monte Carlo code A3MCNP for large-scale shielding problems

A3MCNP (Automatic Adjoint Accelerated MCNP) is a revised version of the MCNP Monte Carlo code, which automatically prepares variance reduction parameters for the CADIS (Consistent Adjoint Driven Importance Sampling) methodology. Using a deterministic 'importance' (or adjoint) function, CADIS performs source and transport biasing within the weight-window technique. The current version of A3MCNP uses the three-dimensional (3-D) Sn transport TORT code to determine a 3-D importance function distribution. Based on simulation of several real-life problems, it is demonstrated that A3MCNP provides precise calculation results with a remarkably short computation time by using the proper and objective variance reduction parameters. However, since the first version of A3MCNP provided only a point source configuration option for large-scale shielding problems, such as spent-fuel transport casks, a large amount of memory may be necessary to store enough points to properly represent the source. Hence, we have developed an improved version of A3MCNP (referred to as A3MCNPV) which has a volumetric source configuration option. This paper describes the successful use of A3MCNPV for a concrete cask neutron and gamma-ray shielding problem, and a PWR dosimetry problem.     

Alignment of protein sequences using the hydrophobic core scores

Making an alignment of the amino acid sequences is an essentialstep in the prediction of an unknown protein structure by modelbuilding from the known structure of a protein of the same family.To improve the accuracy of the alignments, we introduced theconcept of hydrophobic core scores, which restrains puttinginsertions/deletions in the hydrophobic core regions of theprotein. Eight pairs of protein sequences were aligned by thismethod, and the quality of the alignments were assessed byreference to those obtained by the structural superposition.The introduction of the hydrophobic core scores derived fromthe knowledge of the tertiary structure of one of each pairresulted in an improvement of the accuracy of the alignments.The quality of the alignment was found to depend on the homologyof the protein sequences.     

Visualization of PVDF nanofibers coated on filter paper using fluorescein silica nanoparticles

Fluorescein silica nanoparticles (NPs) were prepared using a silane compound bound between fluorescein‐N‐hydroxysuccinimide (NHS‐Fluorescein) and 3‐aminopropylorthosilicate by a sol–gel method. The fluorescein‐silica NPs were mixed with a poly(vinylidene fluoride) (PVDF) solution, and the solution loaded with the NPs was electrospun on a filter paper. Scanning electron microscopy and transmission electron microscopy images confirmed the encapsulation of the fluorescein silica NPs in the PVDF nanofibers. Laser scanning confocal microscopy (LSCM) images showed fluorescein silica NPs as dots, and photoluminescence (PL) images obtained using a fluoroanalyzer indicated the emission of uniform PL from filter papers coated with fluorescein‐silica‐NP‐encapsulated PVDF nanofibers. It was demonstrated that the fluorescein silica NPs enabled PVDF nanofibers coated on a filter paper to be easily visualized. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45125.     

Preparation of catalyst precursors for selective oxidation of n-butane by exfoliation–reduction of VOPO4·2H2O in primary alcohol

A new method through intercalation and exfoliation of VOPO₄·2H₂O crystallites in primary alcohol (1-propanol or 1-butanol), followed by reduction with the alcohol, have been investigated for the preparation of catalyst precursor. Lamellar compounds, consisting of V⁴⁺, P⁵⁺ and alkyl group with thin film-like morphology, were formed and was characterized by means of XRD, IR, TG/DTA, and elemental analysis. The chemical formula of the precursor obtained by exfoliation–reduction in 1-butanol was shown to be VO{(n-C₄H₉)_0.16H_0.84}PO₄·0.8H₂O. On the other hand, a direct reduction of VOPO₄·2H₂O in the alcohol gave a mixed phase shown by (VOHPO₄·0.5H₂O)_0.3(VO{(n-C₄H₉)_0.3H_0.7}PO₄·3H₂O)_0.7 comprising plate-like microcrystallites. These precursors transformed to (VO)₂P₂O₇ phase during an activation process at 703 K in the presence of a mixture of n-butane 1.5% and O₂ 17% in He balance. The obtained (VO)₂P₂O₇ through the exfoliation–reduction was well crystallized and consisted of thin flaky crystallites. It was found that (VO)₂P₂O₇ thus prepared through the exfoliation–reduction was highly active and selective for oxidation of n-butane.     

Fast simulation and rendering techniques for fluid objects

Movies with actions and light effects of fluid objects are aesthetically pleasing and interesting. Until now, the calculation costs of simulation and rendering of fluid objects have been very high. Using a modern PC system and appropriate methods, we achieved a time of 10-20 seconds per frame for this application. Our system uses a full Navier-Stokes equation solver with uniform Eulerian mesh, marching cube isosurface techniques, Catmull-Clark subdivision surface techniques, ray tracing techniques on each vertex and conventional polygon base rendering by HW accelerator. In this paper, we describe the components of our system and the reasons for choosing them. By measuring CPU times of each process for some movie scenes of fluid objects, we evaluate this system. We consider what factors are important for creating movies of fluid objects with short TAT.     

A kinetic study of ‘living’ coordination polymerization of propene with the soluble V(acac)3-Al(i-C4H9)2Cl system

The soluble V(acac)₃-Al(i-C₄H₉)₂Cl system initiated living polymerization of propene at ?78°C affording monodisperse polymers ($\text{M}\text{?}{}_{\mathrm{w}}\text{M}\text{?}{}_{\mathrm{n}}\text{= 1.15 ± 0.10}$). A kinetic study (of the living polymerization) was carried out to evaluate the rate coefficients for propagation. The equilibrium constant K_M for a propene monomer coordinated to an active vanadium and the rate constant k_p for a subsequent insertion of coordinated monomer into a living polymer chain were determined and compared with the values for the polymerization of propene with other soluble vanadium-based catalyst systems. The relation between K_M and k_p revealed that a strong interaction between vanadium and propene is unfavourable for the insertion of the coordinated propene into a living polymer chain. The mechanism of an initiation reaction involving alkylation and complexing of V(acac)₃ with Al(i-C₄H₉)₂Cl has been proposed.     

Guide robot intelligent navigation in urban environments

This paper presents an intelligent robotic system to guide visually impaired people in urban environments. The robot is equipped with two laser range finders, global positioning system (GPS), camera, and compass sensors. All the sensors data are processed by a single laptop computer. We have implemented different navigation algorithms enabling the robot to move autonomously in different urban environments. In pedestrian walkways, we utilize the distance to the edge (left, right, or both) to determine the robot steering command. In difference from pedestrian walkways, in open squares where there is no edge information, artificial neural networks map the GPS and compass sensor data to robot steering command guiding the visually impaired to the goal location. The neural controller is designed such as to be employed even in environments different from those in which they have been evolved. Another important advantage is that a single neural network controls the robot to reach multiple goal locations inside the open square. The proposed algorithms are verified experimentally in a navigation task inside the University of Toyama Campus, where the robot moves from the initial to goal location.