Influence of water content in sub-flooring materials using adhesive on chemical compounds emission

Indoor air pollution is caused predominantly by emission of primary pollutants from building materials or finishing materials. Recently, there has been increasing interest in the new secondary pollutants caused by chemical reaction of the primary pollutants. In this study, the pollutants emitted from poly(vinyl chloride) (PVC) flooring material were measured, and 2-ethyl-1-hexanol (2E1H) and volatile organic compounds (VOCs) emitted from composite building materials made of PVC flooring material used as a self-leveling flooring were measured to identify the mechanism of emission of 2E1H. The moisture sorption isotherm was measured with a Magnetic Suspension Balance to examine the moisture content of the self-leveling flooring material and its effect on emission of 2E1H. 2E1H was emitted from the PVC flooring material through hydrolysis or oxidation of di-2-ethylhexyl phthalate (DEHP). The composite building material including the self-leveling flooring material emitted more 2E1H through hydrolysis over time. It was determined that liquid prevails in the self-leveling flooring material when the water content is higher than 4% and vapor prevails when the water content is lower than 4%. The prevailing liquid in the flooring material contributes to the increased emission of 2E1H and the prevailing vapor in the material did not cause increase in emission of 2E1H. It is considered that control of water in the self-leveling flooring material or concrete slab is very important in order to inhibit emission of 2E1H through hydrolysis of DEHP on the floor.     

Dielectric relaxation phenomenon of rare earth Nd3+ modified bismuth layer ferroelectric ceramics fabricated by plasma active sintering method

Abstract

The crystalline structure, dielectric relaxation and ferroelectric properties of the solid solution, Nd _x Bi_4-x Ti₃O₁₂ (NBIT) compound were measured. The Curie temperature of the NBIT ceramics was determined to be 490°C from dielectric measurements. The dielectric constant of the NBIT ceramics shows a small anisotropic property. Polarization switching was observed using a Sawyer-Tower circuit at 50 Hz. Remnant polarizations and coercive fields could not be confirmed since the hysteresis loops were not saturated. The large dielectric relaxation is observed in the frequency range between 100 kHz and 1 MHz.     

Influence of formic acid on electrochemical properties of high‐porosity Pt/TiN nanoparticle aggregates

Platinum‐deposited titanium nitride (Pt/TiN) nanoparticle aggregates with high porosities were successfully prepared via a self‐assembly‐assisted spray pyrolysis method. The addition of formic acid (HCOOH) had a significant influence on the process, promoting the simultaneous formation of metallic Pt and reduction on the surface of the TiN support material. Complete reduction of the Pt/TiN nanoparticle aggregates improved the catalytic activity. The electrochemical surface area (ECSA) of Pt/TiN with HCOOH (Pt/TiN_w/HCOOH) was 87.15 m²/g‐Pt, which was higher than that of Pt/TiN without HCOOH (Pt/TiN_w/o‐HCOOH). The catalytic durability of Pt/TiN_w/HCOOH was twice that of Pt/TiN_w/o‐HCOOH. An effective strategy for obtaining carbon‐free catalysts with high activities and durabilities was identified. © 2013 American Institute of Chemical Engineers AIChE J, 59: 2753–2760, 2013     

Development of a 385–500 GHz Sideband-Separating Balanced SIS Mixer

A submillimeter (385–500 GHz) low-noise sideband-separating balanced SIS (Superconductor Insulator Superconductor) mixer (Balanced 2SB mixer) with high IRR (Image Rejection Ratio) has been successfully developed, whose SSB (Single SideBand) noise temperature is ～ 200 K (10hf/k) with an image rejection ratio of ≥?～10 dB. Balanced mixers have become a promising technology which would break through the limitation especially in terahertz receivers and heterodyne arrays. However, though there are examples in microwave with relatively worse noise performance, submillimeter and terahertz balanced mixers have rarely been developed in spite of their astronomical importance. The developed balanced 2SB mixer is not only the first one demonstrated at submillimeter frequency range, but also has very low noise, high IRR, wide detectable frequencies (385–500 GHz), and a flat IF output spectrum. The balanced 2SB mixer is composed of three RF hybrids, four DSB (Double SideBand) mixers, two 180° IF hybrids, and an IF quadrature hybrid. Several important performance indicators such as noise temperature, IRR, required LO (Local Oscillator) power, and IF spectra were measured. The measured LO power required for the balanced 2SB mixer was typically ~ 14 dB less than that of the single-ended mixers.     

Study on control of rock fragmentation at limestone quarry

The size distribution of a muck pile depends not on only the blasting standard but also on the mechanical properties, joint system, and crack density of the rock mass. As, the cracks in the rock masses are especially heavily developed at the limestone quarries in Japan, they, along with the joints, have a large impact on the effects of blasting, such as the size of the muck pile. Therefore, if the joint system and/or crack density in a rock mass can be determined and quantitatively evaluated, the blasting operation can be conducted more effectively, efficiently and safely. However, guidelines for designing appropriate blasting standards based on the rock mass conditions have not yet been scientifically developed. Therefore, blasting tests were conducted on different mines and faces, under different geological conditions and blasting standards, in order to determine the impacts of each factor on the effects of blasting. Summarized the results of a series of blasting tests and described the impacts of geological conditions on the size of the muck pile produced by blast. Bhandari S. Engineering rock blasting operations, 1997.     

Turbulent burning velocity of hydrogen–air premixed propagating flames at elevated pressures

Lewis number represents the thermo-diffusive effects on laminar flames. That of hydrogen–air mixture varies extensively with the equivalence ratio due to the high molecular diffusivity of hydrogen. In this study, the influences of pressure and thermo-diffusive effects on spherically propagating premixed hydrogen–air turbulent flames were studied using a constant volume fan-stirred combustion vessel. It was noted that the ratio of the turbulent to unstretched laminar burning velocity increased with decreasing equivalence ratio and increasing mixture pressure. Turbulent burning velocity was dominated by three factors: (1) purely hydrodynamic factor, turbulence Reynolds number, (2) relative turbulence intensity to reaction speed, the ratio of turbulence intensity to unstretched laminar burning velocity, and (3) sensitivity of the flame to the stretch due to the thermo-diffusive effects, Lewis and Markstein numbers. A turbulent burning velocity correlation in terms of Reynolds and Lewis numbers is presented.     

All solid-state battery with sulfur electrode and thio-LISICON electrolyte

A high-capacity type of all solid-state battery was developed using sulfur electrode and the thio-LISICON electrolyte. New nano-composite of sulfur and acetylene black (AB) with an average particle size of 1–10 nm was fabricated by gas-phase mixing and showed a reversible capacity of 900 mAh g⁻¹ at a current density of 0.013 mA cm⁻².     

Development of simplified evaluation method for creep-fatigue crack propagation

In the design assessment of fast reactor plant components, prevention of crack initiation from defect-free structures is a main concern. However, existence of initial defects such as weld defects cannot be entirely excluded and this potential cracks are to be evaluated to determine if initiated cracks do not lead to component failure instantly. Therefore, evaluation of structural integrity in the presence of crack-like defects is also important to complement the formal design assessment. The authors have been developing a guideline for assessing long-term structural integrity of fast reactor components using detailed inelastic analysis and nonlinear fracture mechanics. This guideline consists of two parts, evaluation of defect-free structures and flaw evaluation. In the latter, creep-fatigue is considered to be one of the most essential driving force for crack propagation at high operating temperature exceeding 500 °C. The uses of J-integral-type parameters (fatigue J-integral range and creep J-integral) are recommended to describe creep-fatigue crack propagation behavior in the guideline. This paper gives an outline of the simplified evaluation method for creep-fatigue crack propagation.     

用于CFD计算的急曲率水斗背面贴体网格离散方法

针对冲击式水轮机水斗表面的网格生成方法对计算流体流动、水轮机背面干涉和水轮机效率十分重要,基于边缘等分和定向投影建立了一种能适应急曲率水斗正面和背面贴体网格的生成方法,计算得到了一表面曲率急剧变化的水斗贴体网格.研究表明,此法简单易行,表面适应性强,对急曲率水斗正、背面均能获得均匀、平滑的贴体网格.     

Noise reduction and surge margin improvement using tapered diffuser vane in a centrifugal compressor

Improvement of surge margin and reduction of interaction tone noise radiated from a centrifugal compressor with a vaned diffuser is discussed from experiments and CFD analyses. Two types of one-side tapered diffuser vanes, which are shroud- and hub-side tapered vanes, were used in the experiments. The height of the leading edge of the tapered vanes varied from 100% to 10%. Both types of tapered vanes are effective for the reduction of the inter- action tone noise radiated from the compressor, because of the smaller interaction area between impel- ler-discharge flow and diffuser vane surface. Especially, the hub-side tapered diffuser vane suppresses the evolution of the leading-edge vortex, which causes reverse-flow in the diffuser passage. Furthermore, the hub-side tapered diffuser vane, which has an optimized diffuser leading edge shape, can improve the compressor pressure-rise characteristics at low-flow operation and can enlarge the surge margin.