[en] Stress corrosion cracking(SCC) of stainless steel in pressurized water reactor (PWR) serves as a critical issue in nuclear power plants. Stainless steel exhibits an excellent hightemperature strength, ductility, toughness and corrosion resistance, and has been applied not only in nuclear power plants but also in various heavy industries. However, stress corrosion cracks in stainless steel result in aggravated microstructure, physical and mechanical properties, which critically affect the operation of nuclear power plants. To overcome this problem, several studies on stress corrosion cracking of stainless steel components have been carried out, however, the range of environmental conditions that lead to vulnerable stress corrosion cracking remains yet to be defined. In this study, slow strain rate tests(SSRT) were conducted to produce stress corrosion cracking in 316L stainless steel specimen, with adjusted dissolved oxygen and chlorine concentrations. Since dissolved molecules and ions inside the aqueous solution such as dissolved oxygen and chlorine ions are expected to penetrate the grain boundary, we aim to check whether intergranular stress corrosion cracking (IGSCC) occurs in the specimen under the environment (360°C, 20 MPa, and LiOH (2 ppm) + H₃BO₃ (1200 ppm)) similar to the primary coolants employed in nuclear power plants. To determine the effect of dissolved oxygen and chlorine on the nature of stress corrosion cracking, the experiments were conducted under three distinct environments: air (25°C), primary coolant environment, and primary coolant environment with dissolved oxygen (5 ppm) and chlorine (4 ppm). The stress-strain curve shows that the yield strength, tensile strength, and elongation rate of 316L stainless steel are reduced depending on the environment, leading to the deteriorated mechanical properties. Factors such as temperature, pressure, lithium, boron, and other solutes in the solution affect the microstructure of the material, thus increasing the occurrence rate and sensitivity of stress corrosion cracking. In particular, the mechanical properties of stainless steel 316L greatly deteriorated due to stress corrosion cracking under 5 ppm of dissolved oxygen, 4 ppm of chlorine ions, and 2×10^-7/s strain rate. Observing the cross section of the fractured tensile specimen under scanning electron microscopes (SEM) reveal that the reduction in cross sectional area of the stress-corrosion cracked specimen is the lowest under dissolved oxygen and chlorine (9.7%). Under ambient air and primary environment, further reduction in area has been observed due to necking during ductile fracture. Experiments with dissolved oxygen and chlorine show that cracks form due to stress corrosion cracking. SEM analyses also reveal widely distributed oxides on the surface. Cracks occur on the fracture surface of the specimen along the grain boundary and confirms that IGSCC occurred

[en] We investigate the x-ray diffraction effects from surface acoustic waves (SAW) traveling along a multilayer. The diffraction intensity distribution depends on the incidence angle and the multilayer SAW (MLSAW) amplitude. Particularly, a small departure deviating from the Bragg incidence angle at a certain amplitude will produce a larger variation of the intensity distribution. This shows that the diffraction intensity from MLSAW has an extremely high sensitivity to the Bragg incidence angle, which is different from a SAW traveling along a solid surface without deposited layers. By carefully analyzing the relationship between the intensity distribution I and the incidence angle θ, the corresponding analytic expression of the intensity distribution is theoretically derived. Our theoretical prediction is in great agreement with the experimental results previously obtained. A theoretical model that can be applied to study the x-ray diffraction effect from MLSAW is developed. The extremely high sensitivity to the Bragg angle will help us in acousto-optic instrument research with MLSAW.

[en] In this paper, the opportunity for the inter-regional integration of the electricity market in East China is analysed on the basis of strategies for the future expansion of the electricity generation system. We assume that during its first stage, the operational breakthrough of the electricity sector reform in China will be to achieve an economic dispatch of the generating plants. On the basis of this assumed goal a multi-region model is proposed to appraise the potential benefits of an integrated inter-regional electricity market. This model includes: propositions on design and operation of the market, electricity demand forecasting, least-cost generating system expansion. As case study, three strategies of electricity supply are assessed in two provinces: Shandong and Shanghai in East China. While Shandong is a potential electricity exporter due to availability of primary energy resources, Shanghai is an electricity importer. The strategies include: autarkical expansion of each regional system, import/export only for minimizing operation costs, integration of the system expansion for minimizing total costs including operation and investment costs. One of the findings is that building up an inter-regional integrated electricity market is profitable for both the Shanghai and Shandong regions compared with the two other strategies, if the future regulation makes it possible to insure an economic dispatch of the generating power plants

[en] It is shown that the potential model constructed by the one-gluon exchange interaction plus the scalar linear potential cannot well explain the splittings of P states of heavy quarkonium in this note. However, if the model is modified by the hypothesis that the Lorentz structure of confinement is expressed by a combination of five independent Lorentz invariants, such as scalar, pseudoscalar, vector, axial-vector and tensor-type couplings, we find that the model is able to reproduce almost all the features of the P-state splittings for the cc system. (author)

[en] The finite recovery time Ts of the bleached absorber is presented as one of the possible mechanisms accounting for the increase-maximum-decrease in pulse energy E with the pumping rate Wp in cw-pumped passively Q-switched solid-state lasers, by analytically evaluating the sign of the derivative?E/?Wp. The results show that, in the low pump regime (T>Ts, T is the interpulse period), the initial population density ni remains constant, the final population density nf decreases with Wp, and this results in a monotonic increase of E with Wp. In the high pump regime(T< Ts),ni decreases but nf remains the same with Wp; this results in a monotonic decrease of E with Wp. At the critical region(T?Ts), E reaches its maximum value. A cw-pumped Yb:YAG laser passively Q switched by a Cr4+:YAG absorber is demonstrated to confirm this model. The theoretical model is also applied to the analysis of three previously reported passive Q switching solid-state [Nd:GdVO4,Nd+:LaSc3(BO3)4?(Nd+:LSB), and Nd:YAG] lasers experiments

[en] In the steel making process, it's hard to control the amount and the distribution of nitrogen. Also nitrogen makes spots in the PTA analysis. So it's very important to evaluate the effect of nitrogen on the PTA for the analysis of boron distribution. The objects of this report are like these. - Evaluation of nitrogen effect for analysis of boron distribution by PTA - Evaluation of nitrogen distribution of the boron-free steel by PTA

[en] Yb"3"+/Ho"3"+ codoped LiLuF_4 microparticles have been successfully prepared via a facile hydrothermal method. The crystal phase and morphology of LiLuF_4 microparticles were inspected by x-ray diffraction and scanning electron microscope, respectively. The upconversion emission of single LiLuF_4: Yb"3"+/Ho"3"+ microparticle was carefully studied by a confocal microscopy setup under NIR 980 nm excitation. With the increase of Ce"3"+ ion concentrations of 12%, the ratio of red to green emission of the Ho"3"+ ions of single LiLuF_4 microparticle was boosted about 17-fold, and the output colors were tuned from green to red, which is due to the two efficient cross-relaxation between Ho"3"+ and Ce"3"+ ions enhances the red and suppresses the green in the emission processes. To investigate the optical properties of the single microparticle or nanoparticle through the confocal microscopy setup can effectively avoid the influence of surrounding particle or environment, and could provide more precise information for better exploring the emission mechanisms of rare earth ions. The tunable upconversion emission of Ho"3"+ in single LiLuF_4 microparticle in this work will have great potential applications in the micro optoelectronic devices and color display applications. - Highlights: • The optical properties of the single LiLuF4: Yb3+/Ho3+/Ce3+ microparticle were studied. • The output colors of single LiLuF4 microparticle were tuned from green to red. • The upconversion mechanisms between Ho3+ and Ce3+ ions were discussed based on emission spectrum.

[en] The Yb³⁺/Ho³⁺/Ce³⁺ codoped LaF₃ nanocrystals have been successfully prepared via a facile hydrothermal method. The significant enhancement in the red upconversion emission of Ho³⁺ is successfully obtained in LaF₃:Yb³⁺/Ho³⁺ nanocrystals through introducing of Ce³⁺ under NIR excitation at 980 nm. The red-to-green emission ratio of Ho³⁺ is enhanced 18.9-fold with Ce³⁺ concentration increasing to 12%, which is due to the two efficient cross relaxation processes of ⁵I₆ (Ho³⁺)+²F_5/2 (Ce³⁺)→⁵I₇ (Ho³⁺)+²F_7/2 (Ce³⁺) and ⁵S₂/⁵F₄ (Ho³⁺)+²F_5/2 (Ce³⁺)→⁵F₅ (Ho³⁺)+²F_7/2 (Ce³⁺) between Ho³⁺ and Ce³⁺ ions. The enhancement mechanism of red emission and conversion efficiency between Ho³⁺ and Ce³⁺ are investigated in detail.

[en] The emission cross-section, and fluorescence lifetime of Cr,Yb:YAG with different concentration of Cr⁴⁺ and Yb:YAG were measured. With the increase of Cr concentration in Cr,Yb:YAG, the emission cross-section keeps constant and fluorescence lifetime decreases. The quantum efficiency decreases and the energy transfer efficiency from Yb³⁺ to Cr⁴⁺ increase as the Cr concentration increases in Cr-Yb-co-doped Cr,Yb:YAG system. The nonradiative Yb³⁺→Cr⁴⁺ energy transfer is consistent with an electric dipole-dipole interaction mechanism. The optimum Cr concentration for Cr,Yb:YAG was estimated. Also the potential of Cr,Yb:YAG as a self-Q-switched laser crystal was discussed

[en] Experiments were carried out to investigate the flow and mass transfer characteristics of an orifice nozzle. Measurements of primary and suction flow rates, dissolved oxygen concentration, and electric power were obtained. Vertically injected mixed-jet images were captured by a direct visualization technique with a high speed camera unit. The mass ratio, volumetric mass transfer coefficient, and mass transfer performance were calculated using the measured data. As the primary flow pressure increases, the mass ratio decreases slightly, while the volumetric mass transfer coefficient and electric power increase. As the primary flow pressure increases and the mass ratio decreases, the mass transfer rate increases because of the fine bubbles and wider distribution of the bubbles