Laser ultrasonic characterisation of branched surface-breaking defects

Surface-breaking defects often have a geometry which is more complicated than the ‘normal slot’ used in many calibration tests, and this geometry will affect the reflection and transmission of ultrasonic surface waves incident on the defect. We present here measurements on defects with varied branched geometries, designed to simulate stress corrosion cracking (SCC) type defects, characterising the geometry using laser-based ultrasonic generation and detection of Rayleigh waves. We show the behaviour of the near-field enhancement and the far-field reflection as a function of branch position and length, and signal analysis which can be used to gain further information for characterising the defect geometry. The experimental results and finite element method (FEM) models presented in this paper highlight the potential of this technique to test components prone to developing SCC, in order to identify and characterise surface-breaking defects.     

Vermiculite/polyacrylamide copolymers microspheres for profile control in oilfields

Polyacrylamide copolymers (PAMVT) microspheres were prepared through inverse emulsion polymerization by using acrylic acid (AA), 2‐acrylamido‐2‐methylpropane sulfonic acid (AMPS) as functional monomers, N,N′‐methylene bis‐acrylamide (MBA) as crosslinker and modified vermiculite (MVMT) with the single‐factor experiments. The initial and swelled particle sizes were tested through the dynamic light scattering (DLS). The swelled particle size under the optimum conditions could be 1.98 μm. The structure was characterized through Fourier transform infrared (FTIR), which indicated that vermiculite has successfully modified and the polymerization reaction was completed. The scanning electron microscopy (SEM) shows that MVMT was evenly filled with PAM copolymers. The water absorption capacity can be up to 80.2%. The recovery efficiency of the water flooding was increased from 69.33% to 77.56%. All these results indicated that the microspheres emulsions could be used as profile control agent to enhance the recovery efficiency. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44918.     

A chemically amplified molecular glass resist with an ionic photoacid generator and a single protection group

A molecular glass resist with an ionic photoacid generator and a single protection group (MR‐1) has been developed. MR‐1 exhibited good thermal properties, such as a 5% weight loss temperature (T_d5%) of 167°C and a glass transition temperature (T_g) of 80°C. MR‐1 showed the good sensitivity of 80 μC/cm² and high contrast of 4.9 with e‐beam exposure (50 keV). A relatively high resolution of 50 nm and low Line‐Edge‐Roughness of 3.8 nm were obtained by e‐beam exposure (100 keV). © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39769.     

Degradation mechanisms in Li‐ion batteries: a state‐of‐the‐art review

One of the most prominent energy storage technologies which are under continuous development, especially for mobile applications, is the Li‐ion batteries due to their superior gravimetric and volumetric energy density. However, limited cycle life of Li‐ion batteries inhibits their extended use in stationary energy storage applications. To enable wider market penetration of Li‐ion batteries, detailed understanding of the degradation mechanisms is required. A typical Li‐ion battery comprised of an active material, binder, separator, current collector, and electrolyte, and the interaction between these components plays a critical role in successful operation of such batteries. Degradation of Li‐ion batteries can have both chemical and mechanical origins and manifests itself by capacity loss, power fading or both. Mechanical degradation mechanisms are associated with the volume changes and stress generated during repetitive intercalation of Li ions into the active material, whereas chemical degradation mechanisms are associated with the parasitic side reactions such as solid electrolyte interphase formation, electrolyte decomposition/reduction and active material dissolution. In this study, the main degradation mechanisms in Li‐ion batteries are reviewed. Copyright © 2017 John Wiley & Sons, Ltd.     

Environmental policy and Japanese society: part II. lessons about Japan and about policy

This paper analyzes Japanese environmental policy to draw lessons about Japanese society and about environmental policy. It critically examines three myths about Japan: the myth of consensus, the myth of centralization, and the myth of rational policy. The paper then discusses the implications of Japan's experiences for the relationship between environmental quality and economic growth, the problems of an administrative system to compensate pollution victims, and the difficulties in establishing a system for environmental impact assessment. Part I of the essay, appears on p. 191 of this journal, examined successes and failures of Japanese environmental policy.     

Nanoscratch Characterization of GaN Epilayers on c- and a-Axis Sapphire Substrates

In this study, we used metal organic chemical vapor deposition to form gallium nitride (GaN) epilayers on c- and a-axis sapphire substrates and then used the nanoscratch technique and atomic force microscopy (AFM) to determine the nanotribological behavior and deformation characteristics of the GaN epilayers, respectively. The AFM morphological studies revealed that pile-up phenomena occurred on both sides of the scratches formed on the GaN epilayers. It is suggested that cracking dominates in the case of GaN epilayers while ploughing during the process of scratching; the appearances of the scratched surfaces were significantly different for the GaN epilayers on the c- and a-axis sapphire substrates. In addition, compared to the c-axis substrate, we obtained higher values of the coefficient of friction (μ) and deeper penetration of the scratches on the GaN a-axis sapphire sample when we set the ramped force at 4,000 μN. This discrepancy suggests that GaN epilayers grown on c-axis sapphire have higher shear resistances than those formed on a-axis sapphire. The occurrence of pile-up events indicates that the generation and motion of individual dislocation, which we measured under the sites of critical brittle transitions of the scratch track, resulted in ductile and/or brittle properties as a result of the deformed and strain-hardened lattice structure.     

煤化工反渗透浓缩液的“零排放”技术的研究现状

随着近年来煤炭市场的萧条,我国煤炭企业面临着长期深度调整。可以预见,煤化工作为煤炭领域一个新的增长点,将在未来几年中得到广泛关注。然而,煤化工废水的处理,将成为制约企业发展的关键点。目前广泛采用的双膜法,虽然能够有效分离废水中的有机物和无机盐,但是所产生的反渗透浓缩液仍然难以处理。根据这一问题,探讨了现阶段可以采用的反渗透浓缩液深度处理技术和工艺,以及"零排放"技术面临的问题。     

Polygeneration of hydrogen and power based on coal gasification integrated with a dual chemical looping process: Thermodynamic investigation

This paper assesses, from a thermodynamic perspective, the conversion of coal to power and hydrogen through gasification simultaneously with a dual chemical looping processes, namely chemical looping air separation (CLAS) and water–gas shift with calcium looping CO₂ absorption (WGS-CaL). CLAS offers an advantage over other mature technologies in that it can significantly reduce its capital cost. WGS-CaL is an efficient method for hydrogen production and CO₂ capture. The three major factors, oxygen to coal (O/C), steam to coal (S/C) and CaO to coal (Ca/C) were analyzed. Moreover, the comparisons of this suggested process and the traditional processes including integrated gasification combined cycle (IGCC), integrated gasification combined cycle with carbon capture and storage (IGCC-CCS) and integrated gasification combined cycle with calcium-based chemical looping (IGCC-CaL) were discussed. And, the exergy destruction analysis of this suggested process has also been calculated.