最新刊期
      卷 43 ， 期 5 ， 2011
      • Vol. 43, Issue 5, Pages: 27-31(2011)
        摘要：Abstract:Analysis of seismic response is very important to the seismic design of bridge. Based on theory of random vibration and response spectral method, the mean square root response of the internal forces of high-piers and long-span continuous rigid frame-beam bridge subjected to the stationary random seismic excitation and varying spatial seismic action was investigated. The conclusions showed that the analysis of random vibration is in accord with the response spectrum method excluding the spatial variation effect of the seismic action. The wave propagation effect and the coherence loss would surely change the internal forces of the continuous rigid frame-beam bridges and the computed conclusions by random vibration are greater than by response spectrum in most circumstance. The large differences of the site conditions of the bases significantly change the response of the continuous rigid frame-beam bridges, which should be included in the seismic design of the bridges.  
        关键词：continuous rigid frame;seismic analysis;random vibration;response spectrum;power spectral density   
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        发布时间：2023-11-14
      • Vol. 43, Issue 5, Pages: 64-70(2011)
        摘要：Abstract:In order to study the long-term mechanical properties of the diabase in Dagangshan hydropower station dam site,triaxial rheological tests under different stress paths were carried out on RLW-1000 rheology testing machine,and the stress-strain-time curves under different conditions were obtained.The results showed that the diabase was typical hard-brittle rock which had obvious rheological threshold,and sudden brittle fracture was shown at failure of specimen.Shortly prior to failure, each specimen experienced transient creep,steady-state creep and tertiary creep stage in the fracture stress level,but the transient creep and tertiary creep stage maintained short time. When the applied stress level was closed to the fracture stress,the circumferential creep rates were higher than those of axial, which were the main reason of the volume dilatancy phenomenon of specimen.The continuous development of damage in rheological process caused the decrease of whole strength of rock mass,so the rheological failure strength was lower than the instantaneous failure strength by the triaxial compression test.There was some degree of alteration in the diabase of Dagangshan hydropower station dam site,and the altered minerals showed fine scale-like aggregation.The strength of rock was impaired by the existence of alerted strip,the rupture of rock can occur easily in the interface of poorly crystallized mineral grains and the poorly cemented ones.  
        关键词：rheology experiment;diabase;triaxial rheology;rheological failure mechanism;hard-brittle rock   
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        发布时间：2023-11-14
      • Vol. 43, Issue 5, Pages: 209-212(2011)
        摘要：Abstract:The Tb^3+-doped strontium carbonate phosphor was synthesized via co-precipitation route by microwave assisted.The phosphor powders were characterized by scanning electron microscopy(SEM),X-ray diffraction(XRD) and photoluminescence and photoluminescence excitation(PL-PLE) spectrum. The results showed that Tb^3+acting as a luminescent center probed into the single orthorhombic phase of SrCO3 with flake-like and sphericity-like.The PLE spectrum showed a broadband absorption center in 231 nm,which belonged to 4f7→5d1transition.The sample was the green phosphor since the maximum emission peak located in the vicinity of 543 nm,corresponding to the transition of ^5D4→^7F5.The luminescent intensities increased with increasing Tb^3+concentration, and then decreased because of concentration quenching.The optimal concentration of Tb^3+ was 3.5 mol%.The concentration self-quenching mechanism is exchange interaction.  
        关键词：microwave assisted;co-precipitation;SrCO3;green phosphor   
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        发布时间：2023-11-14
      • Vol. 43, Issue 5, Pages: 224-227(2011)
        摘要：Abstract:A elasticity mechanical theory model for magnetoelectric bilayer laminated films with substrate was established.Using this model, the transverse and longitudinal magnetoelectric voltage coefficient formula of magnetoelectric films were derived in non-ideal interface coupling state simply. The magnetoelectric voltage coefficient of PMN-PT/CFO bilayer laminated films was calculated as the function of the volume fraction vof piezoelectrics, volume fraction vs of substrates and interface coupling coefficientk. It was found that the substrate has strong clamping effect to the magnetoelectric thin films. The thickness of substrate, quality of interface coupling and appropriated volume ratio of piezoelectrics/piezomagnetics have much effect on the magnetoelectric conversion in a certain extent.  
        关键词：magnetoelectric effect;magnetoelectric films;coupling coefficient   
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        发布时间：2023-11-14
      • Vol. 43, Issue 5, Pages: 175-178(2011)
        摘要：Abstract:Based on the definition of multi-infeed interaction factor and multi-infeed effective short circuit ratio, DC power support factor was defined. For different AC/DC power delivery channel failures of Sichuan power grid, DC power support factor was used to carry on sorting to each emergency DC power support’s effect and select the best support strategy. The simulation confirmed the analysis result of DC power support factor and indicated that DC power support factor can effectively assess the effect of emergency DC power support.  
        关键词：AC/DC power systems;emergency DC power support;short circuit ratio(SCR);DC power support factor;transient stability   
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        发布时间：2023-11-14
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