Comparison of various revised k–ε models and LES applied to flow around a high-rise building model with 1:1:2 shape placed within the surface boundary layer

This paper compares computational fluid dynamics (CFD) results using various revised k–ε models and large eddy simulation (LES) applied to flow around a high-rise building model with 1:1:2 shape placed within the surface boundary layer. The first part of the paper examines the accuracy of various revised k–ε models, i.e. LK model, MMK model and Durbin's revised k–ε model, by comparing their results with experimental data. Among the computations using various revised k–ε models compared here, Durbin's revised k–ε model shows the best agreement with the experiment. The reason for the good performance of Durbin's model is discussed on the basis of ‘Realizability’ of predicted results. The second part of the paper describes the computations based on LES with and without inflow turbulence applied to the same flowfield. The results are compared with those of the experiments and Durbin's k–ε model in order to clarify the effect of velocity fluctuations on prediction accuracy of time-averaged velocity fields around the building. Special attention is paid to prediction accuracy for reproducing flow behind a building. The LES results with inflow turbulence show generally good agreement with experimental results in terms of the distributions of velocity and turbulence energy in this region. This improvement is mainly due to the fact that the periodic velocity fluctuation behind the building is well reproduced in LES.     

Reversible Coloration Enhanced by Electrochemical Deposition of an Ultrathin Zinc Layer onto an Anodic Nanoporous Alumina Layer

A productive method is introduced to realize large area color electronic paper (e‐paper) with high UV resistance, heat resistance, and good significant bending properties using a color change triggered by reversible electronic change in the device structure. Reversible coloration and decoloration triggered by electrochemical deposition and desorption, respectively, of an ultra‐thin zinc (Zn) layer on a thin transparent conductive layer coated on anodic nanoporous alumina has been developed. The deposition of the ultra‐thin Zn layer triggers the formation of destructive interference, which leads to coloration. Yellow, magenta, and cyan colors were obtained in the colored state by increasing the NP‐Al₂O₃ layer thickness, based on Bragg diffraction theory. Reflectance of more than 70% and contrast values of more than 7 were obtained, which are nearly equivalent to those of previous e‐papers. The color images in these devices also showed high UV resistance, heat resistance, and repeated significant bending endurance. The devices can be fabricated with large areas using low‐cost manufacturing processes such as anodic oxidation, and use abundantly available materials. Our proposed device provides low‐cost and flexible large area color e‐paper for outdoor use.     

Layered Silicon Nitride-Based Composites with Discontinuous Boron Nitride Interlayers

The influence of a strong/weak interface ratio on the mechanical properties of Si₃N₄/BN-based layered composites was studied. The ratio was controlled by the number of BN spots between the adjacent Si₃N₄ layers. By increasing the BN interface area from 0% to 72%, fracture toughness increased from 7.7 to 10.9 MPa·m^1/2, and bending strength decreased from 1275 to 982 MPa. Fracture toughness was improved from 8.6 to 10.1 MPa·m^1/2 by additional heat treatment of samples containing 2 vol%β-Si₃N₄ seed particles. The bending strength of samples with 35% weak BN interfaces, measured perpendicular and parallel to layer alignment, was 1260 and 1240 MPa, respectively. This confirmed the two-directional isotropy of layered samples.     

Removal of cadmium and lead from soil using aescin as a biosurfactant

Remediation of a soil contaminated with cadmium or lead was performed by a soil washing process using aescin as a biosurfactant. The removal of cadmium and lead from the soil was evaluated as a function of aescin concentration and pH in a batch process. A 30-mM aescin solution was most effective in the removal of cadmium and lead at pH 6.8. Cadmium and lead migrated from the soil to the aescin-containing aqueous phase, depending on the pH value. We found that 41% of cadmium (pH 7.8) and 25% of lead (pH 2.8) in the soil matrix migrated into a 30-mM aescin solution. Also, the complexation of aescin with cadmium and lead ions was confirmed by Fourier transform infrared spectroscopy and electrical conductivity measurements. As a result, the maximal complexation capacity of aescin with metal ions was approximately aescin/cadmium=2∶1 and aescin/lead=3∶1 on a molar basis. It was suggested that aescin may sequester cadmium and lead ions by the carboxylic and saccharide moieties. Then, the complex of aescin with cadmium or lead may migrate to the aqueous phase as the result of dispersion.     

MAC Enhancement for High Speed Communications in the 802.15.3c mmWave WPAN

Millimeter-wave (mmWave) is highly focused as a powerful mean enabling to perform very high data transmission. This paper proposes the enhancement of media access control (MAC) for the mmWave WPAN. The existing MACs have limits to achieve high data transmission over 1–2 Gbps by reasons of the low frame transmission efficiency and the high overhead of signal exchanges. In addition, the transmitting frames need to be protected in a poor channel condition for the high quality of service. The proposed MAC provides frame aggregation with unequal error protection (UEP) and block acknowledgment (Blk-ACK), which can solve the problems of the existing MACs and guarantee the high quality of service. Our theoretical throughput analysis shows that the proposed MAC does the high throughput enhancement compared to the existing MACs and achieves the MAC throughput over 2Gbps in the mmWave WPAN.     

Process Model of Design and Construction Activities of a Building

This article presents a new method to represent the design and construction process in a systematic way and to develop a support system of management for concurrent engineering. We define activities included in the total process of a standard project, make an adjacency matrix about the relationship among activities, and structure the activities with a reachability matrix. As a result, the process consisting of several complicated interactions among activities was found. These interactions can be classified into three patterns. We constructed a new process model by dividing the information flow into nine categories. Moreover, the effectiveness of the model as a tool for concurrent engineering is discussed from four points of view, and the rellationship between concurrent engineering and project objectives is analyzed. This article shows the results matrix calculation first and then describes its contribution to concurrent engineering.     

Low-Temperature Sintering and High Thermal Conductivity of YLiO2-Doped AlN Ceramics

The present work indicates through thermodynamic considerations that YLiO₂ additive is beneficial for low-temperature sintering of AlN ceramics. Pressureless sintering of commercially available AIN powders with simultaneous additions of YLiO₂ and CaO resulted in materials with high thermal conductivity (170 W·m^–1·K^–1 after sintering at 1600°C for 6 h). It is demonstrated that improvement of thermal conductivity is possible at low firing temperature by use of sintering aids.     

Enhancement of xylose uptake in 2-deoxyglucose tolerant mutant of Saccharomyces cerevisiae

Chemical mutation of Saccharomyces cerevisiae using ethyl methane sulfonate was performed to enhance its ability of xylose uptake for ethanol production from lignocellulose under microaerobic condition. Among the appeared mutants, the mutant no. 2 (M2) strain screened using inhibitory effects of 2-deoxyglucose (DOG) showed more than 4-fold high ability in xylose uptake compared with the wild type strain, under the presence of glucose. The catabolite repression by glucose was sufficiently reduced in M2 strain due to its tolerance to the high concentration of DOG (0.5%, wt./vol.). Metabolomic analyses of various sugars in the cell revealed that some of xylose was reduced to xylitol in M2 cell, providing the concentration gradient of xylose and more uptake of xylose. Xylulose-5-phosphate was significantly detected in the crude cell extract from M2 strain, indicating higher metabolic activity in pentose phosphate pathway. This was also confirmed by in vitro analyses of key enzymes involved in glucose and xylose metabolism, such as hexokinase, glucose-6-phosphate dehydrogenase and xylose reductase. Glucose uptake was moderately suppressed in the presence of trehalose-6-phosphate inhibiting the activation of hexokinase, resulting in more uptake of xylose through hexose transport system. To our knowledge, this study is the first report verifying that the mutation technique successfully enhances the xylose uptake by S. cerevisiae, particularly under the presence of glucose.     

Identification of a Point Mutation in the Granule-bound Starch Synthase I Gene (GBSSI) in a waxy Diploid Wheat Mutant and Design of Molecular Markers for Backcrossing

In cereals, granule-bound starch synthase I (GBSSI)-deficient mutants accumulate glutinous (amylose-free) starch in their storage tissues. The amylose-free starch produced by waxy (wx) mutants of hexaploid bread wheat (Triticum aestivum L.) is used in cakes and breads. However, wx mutants of diploid wheat (T. monococcum L.) have so far no commercial applications. In this study, we identified a mutation in exon 6 of GBSSI in a diploid wheat wx mutant that resulted in the replacement of Trp355 with a stop codon. Molecular markers were developed for the rapid screening of the mutation, which should allow the selection of heterozygous and homozygous plants during backcrossing. This will facilitate the improvement of the agricultural traits of the wx mutant and the generation of new amylose-free wx lines.