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A non-closed hydrothermal synthetic processing is improved to synthesize Sm3+ doped β-NaYbF4 nano-phosphors at 98 °C without any high-temperature and high-pressure treatments as a final step. Novel green, red, and near-infrared broadband (799-873 nm) upconversion emissions of Sm3+-doped β-NaYbF4 nano-phosphors under 980 nm excitation are observed. These UC emissions can be assigned to the Sm3+ transitions of 4GJ, 4F3/2 and 6F11/2→6HJ. The half-width of 873 nm emission band is broadened nearly two-fold through the annealing treatment for nano-phosphors. The upconversion process in Yb3+-Sm3+ system is discussed based on energy transfer mechanisms. 相似文献
74.
CUI YuanQing & YANG Wei School of Aerospace Engineering Applied Mechanics Tongji University Shanghai China University Office Zhejiang University Hangzhou 《中国科学:物理学 力学 天文学(英文版)》2011,(5)
Experimental results indicate three regimes for cracking in a ferroelectric double cantilever beam (DCB) under combined electromechanical loading. In the loading, the maximum amplitude of the applied electric field reaches almost twice the coercive field of ferroelectrics. Thus, the model of small scale domain switching is not applicable any more, which is dictated only by the singular term of the crack tip field. In the DCB test, a large or global scale domain switching takes place instead, which is driven... 相似文献
75.
Xue-Long HeMei Liu Guan-Jun YangSheng-Qiang Fan Chang-Jiu Li 《Applied Surface Science》2011,258(4):1377-1384
Flexible Pt counter electrodes (CEs) were prepared on indium-doped tin oxide coated polyethylene naphthalate (ITO-PEN) substrate by electroless deposition. The correlation between the microstructure and the property of the Pt CEs was investigated. Results showed that isolated Pt nanoparticles were uniformly distributed on the ITO surface at a short deposition duration, and then grew with the deposition duration, leading to the interconnection of adjacent Pt nanoparticles. The interconnection of Pt nanoparticles was beneficial to the electrical property of the Pt CEs, while it was unfavorable to the electrocatalytic property of the Pt CEs. A microstructure model was proposed to explain the correlation between the microstructure and the property of the Pt CEs. In addition, the Pt CEs showed low charge transfer resistance (1.66-0.58 Ω cm2), which was comparable to that (1.16 Ω cm2) of the conventional sputtered Pt CE. The high electrocatalytic property of the electroless deposited Pt CEs makes the assembled DSCs present comparable energy conversion efficiency of the DSCs using sputtered Pt CE. 相似文献
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P.V. Yasniy I.B. Okipnyi P.O. Maruschak R.T. Bishchak A.P. Sorochak 《Theoretical and Applied Fracture Mechanics》2011,56(2):63-67
Fracture toughness of heat-resistant steel can be increased by a preliminary thermomechanical loading called warm pre-stressing (WPS). The procedure creates a plastic deformed area around the crack tip and hence allows larger service loads to be tolerated by the cracked specimen. It is shown that a hydrogenation in the preloading stage decreases the fracture toughness of material.Investigations are also presented of the applicability of physical and mechanical approaches for the prediction of cleavage stress of materials after preliminary plastic deformation (PPD) effects and hydrogenation. Different schemes of the plastic deformation and influence of hydrogenation are considered in the preloading stage to provide different levels cleavage stress of steel 15Kh2MFA. 相似文献
78.
This paper describes an Integer Programming model for generating stable loading patterns for the Pallet Loading Problem under several stability criteria. The results obtained during evaluation show great improvement in the number of stable patterns in comparison with results reported earlier. Moreover, most of the solved cases also ensure optimality in terms of utilization of a pallet. 相似文献
79.
D.G. Pavlou 《Mechanics Research Communications》2011,38(8):546-552
An analytic solution of a thin layer bonded on a visco-elastic medium under the action of in-plane and lateral pulse loads is presented. The analysis is based on double integral transforms with respect to space and time. Representative examples are studied and discussed to determine the influence of the (a) damping and elastic coefficients of visco-elastic medium, and (b) in-plane compression and stretching of the thin layer on wave propagation. 相似文献
80.
This paper considers the treatment of fluid–solid interaction problems under shock wave loading, where the solid experiences large bulk Lagrangian displacements. This work addresses the issues associated with using a level set as a generalized interface for fluid–solid coupling where the fluid–solid interface is embedded in an unstructured fluid grid. We outline the formulation used for the edge‐based unstructured‐grid Euler solver. The identification of the fluid–solid interface on the unstructured fluid mesh uses a super‐sampled ??2 projection technique, which in conjunction with a Lagrangian interface position, permits fast identification of the interface and the concomitant imposition of boundary conditions. The use of a narrow‐band approach for the identification of the wetted interface is presented with the details of the construction of interface conditions. A series of two and three‐dimensional shock‐body computations are presented to demonstrate the validity of the current approach on problems with static and dynamic interfaces, including projectile/shock interaction simulations. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献