Multiscale model for moisture transport with adsorption phenomenon in concrete materials

Abstract

We consider a new two-scale problem which is given as a mathematical model for moisture transport arising in a concrete carbonation process. In research for moisture transport, it is a crucial step how to describe the relationship between the relative humidity and the degree of saturation, mathematically. Here, we have proposed the two-scale model consisting of the diffusion equation for the relative humidity in a macro domain and the free boundary problems describing the relationship in infinitely micro domains. Accordingly, the structures of the micro domains are unknown in our model. This is a significant feature of our new model to emphasize. The aim of this paper is to establish local existence in time and uniqueness of a solution to the model.     

Evolution of long-period stacking order (LPSO) in Mg97Zn1Gd2 cast alloys viewed by HAADF-STEM multi-scale electron tomography

We have studied three-dimensional (3D) structures and growth processes of 14H-type long-period stacking order (LPSO) formed in Mg₉₇Zn₁Gd₂ cast alloys by single tilt-axis electron tomography (ET) using high-angle annular dark-field scanning transmission electron microscopy. Evolution of the solute-enriched stacking faults (SFs) and the 14H LPSO by ageing were visualised in 3D with a high spatial resolution in multi-scale fields of views from a few nanometres to ~10 μm. Lateral growth of the solute-enriched SFs and the LPSO in the (0?0?0?1)_Mg plane is notable compared to the out-of-plane growth in the [0?0?0?1]_Mg direction. The 14H LPSO grows at the cost of decomposition of the (Mg, Zn)₃Gd-type precipitates, and accompany a change of in-plane edge angles from 30 to 60°. We have updated the Time–Temperature–Transformation diagram for precipitation in Mg₉₇Zn₁Gd₂ alloys: starting temperatures of both solute-enriched SFs and LPSO formation shifted to a shorter time side than those in the previous diagram.     

A video camera system for coaxial observation of a sample with an incident soft X‐ray beam

A video camera system for observing a sample from the direction of an incident soft X‐ray beam has been developed. The sample is seen via two reflecting mirrors. The first mirror, which has a hole to allow the soft X‐ray beam to pass through, is set on the beam axis in a vacuum. The second mirror is used to cancel out the mirror inversion of the image. This camera system is used for efficient positioning of samples in a soft X‐ray beam.     

Mathematical model for hysteresis phenomenon in moisture transport of concrete carbonation process

From civil engineering point of view it is very important to construct and analyze a mathematical model for a mechanism of concrete carbonation process. On this subject there are several mathematical results concerned with a one-dimensional model, in which hysteresis effects are neglected. Our aim is to give a model with hysteresis effects appearing in carbonation process. In this paper, as the first step of this research we focus only on moisture transport in the process and propose an initial boundary value problem for a system of partial differential equations as a mathematical model. Also, we give results on the existence of a solution to the problem, globally in time and the uniqueness in only one-dimensional case without proofs.     

Spontaneous emulsification at oil–water interface by tetraalkylammonium chloride

Water droplets were formed spontaneously at the interface of the 2-nitrophenyloctyl ether and aqueous phases on the oil phase side when the oil contained tetraalkylammonium chloride without surfactants. The droplets, less than some micrometers in diameter, gathered at the interface. The number density of the droplets was proportional to the concentration of tetraethylammonium chloride, and hence this salt should be responsible for the formation of the droplets as a surfactant. When positive voltage was applied to the aqueous phase against the oil, the droplets departed from the interface toward the oil bulk. The droplets should be negatively charged by chloride. The adsorption model of the salt was suggested, in which chloride is immobilized at the interface on the aqueous side electrostatically with tetraethylammonium ion on the oil side.     

Real Time and Full-range Complex Fourier Domain Optical Coherence Tomography

High speed complex full-range Fourier domain optical coherence tomography (FD-OCT) is demonstrated. This FD-OCT requires only a single A-scan for each single transversal position for full-range Fourier domain optical coherence tomography. The Fourier transform method is applied along the direction of the B-scan to reconstruct complex spectra, and the complex spectra compose a full-range OCT image.     

Computer-Generated Holograms Based on the Three-Dimensional Fourier Spectrum

A method to synthesize a computer-generated hologram (CGH) of real-existing objects from projection images is proposed. Different from other similar methods, our method enables the synthesis of a CGH with only one-dimensional (1-D) mechanical scanning of the objects. Our method is connected with the three-dimensional (3-D) Fourier spectrum of the objects by the 3-D central slice theorem (CST). Two efficient recording techniques for projection images and numerical experiments to verify our principle is discussed. A comparison between the two techniques is also presented from the viewpoint of diffraction efficiency. © 2005 The Optical Society of Japan     

Use of cheaper metal than Rh, CHCl3-free Pd catalyst, in 1,2-addition of aromatic aldehydes with arylboronic acids

Pd(OAc)₂-(±)-tol-BINAP-catalyzed arylation reaction of aromatic aldehydes with arylboronic acids in the absence of CHCl₃ is described.     

Application of Surface Relief Hologram Using Azobenzene Containing Polymer Film

Surface relief holograms are fabricated by irradiation of laser interference patterns on an azobenzene polymer film. The hologram needs no post-treatment, and can be erased by heating the films to above its glass transition temperature. Rewritable Fresnel holograms are fabricated on azo-polymer film. Replication of the surface relief hologram is also demonstrated. An application for business cards is considered.