本文系统阐述了微动H/V(Horizontal to Vertical)谱比法的计算原理及其在岩土工程勘察中的应用。微动H/V谱比的本质为震动在不同岩土层结构中传播时垂直方向与水平方向的能量分配占比,通过5组实测微动信号的H/V谱比的结果分析,验证了H/...本文系统阐述了微动H/V(Horizontal to Vertical)谱比法的计算原理及其在岩土工程勘察中的应用。微动H/V谱比的本质为震动在不同岩土层结构中传播时垂直方向与水平方向的能量分配占比,通过5组实测微动信号的H/V谱比的结果分析,验证了H/V谱比法在岩土层探测领域的稳定性,即微动H/V谱比能够直接反映地下岩土层的结构变化。研究通过近似地质条件下的实例验证,建立了基岩埋深与H/V谱比最大峰值频率的拟合关系,拟合优度R^(2)均高于0.9,显著提升了土石分界面探测精度。结合H/V谱比剖面和速度剖面的联合解译,进一步提高了土石分界面探测结果的准确性。此外,在古城墙遗址探测中的应用案例表明,该方法对地下人工构筑物具有高灵敏度性,可有效识别地下构筑物及其背景地层。实践证实微动H/V谱比法具备现场操作简便、探测精度高、分辨率强等优势,为岩土工程勘察提供了高效、准确且对环境无干扰的技术手段,具有重要的推广价值。展开更多
The effect of synthesis methods on the activity of V/Ce/WTi catalysts was investigated for the selective catalytic reduction（SCR） of NO_x by NH_3. V/Ce/WTi-DP（deposition precipitation） catalyst showed excellent NH...The effect of synthesis methods on the activity of V/Ce/WTi catalysts was investigated for the selective catalytic reduction（SCR） of NO_x by NH_3. V/Ce/WTi-DP（deposition precipitation） catalyst showed excellent NH_3-SCR performance, especially the better medium-temperature activity and the less N_2O formation than V/Ce/WTi-IMP（impregnation）. These catalysts were characterized by X-ray diffraction（XRD）, Brumauer-Emmett-Teller（BET）, X-ray photoelectron spectroscopy（XPS）, temperature-programmed reduction（H_2-TPR）, and in situ DRIFTS techniques. The XPS and H_2-TPR results revealed that V/Ce/WTi-DP exhibited more surface Ce species, higher level of Oα and higher reducibility of Ce species. Reflected by in situ DRIFTS results, the deposition precipitation method（DP） contributed to a greater amount of weakly adsorbed NO_2, monodentate nitrate and NH_3 species with better reactive activity. Meanwhile, the cis-N_2O_2^（2-） species, an intermediate for N_2O formation, was very limited. As a result, these advantages brought about the superior SCR activity and N_2 selectivity for V/Ce/WTi-DP.展开更多
In this paper, an optimal V-cycle multigrid method for some conforming and nonconforming plate elements are constructed. A new method dealing with nonnested multigrid methods is presented.
Based on Zak＇s stress function, the eigen-equation of stress singularity ofbi-materials with a V-notch was obtained. A new definition of stress intensity factor for a perpendicular interfacial V-notch of bi-material ...Based on Zak＇s stress function, the eigen-equation of stress singularity ofbi-materials with a V-notch was obtained. A new definition of stress intensity factor for a perpendicular interfacial V-notch of bi-material was put forward. The effects of shear modulus and Poisson＇s ratio of the matrix material and attaching material on eigen-values were analyzed. A generalized expression for calculating/（i of the perpendicular V-notch of bi-materials was obtained by means of stress extrapolation. Effects of notch depth, notch angle and Poisson＇s ratio of materials on the singular stress field near the tip of the V-notch were analyzed systematically with numerical simulations. As an example, a finite plate with double edge notches under uniaxial uniform tension was calculated by the method presented and the influence of the notch angle and Poisson＇s ratio on the stress singularity near the tip of notch was obtained.展开更多
文摘本文系统阐述了微动H/V(Horizontal to Vertical)谱比法的计算原理及其在岩土工程勘察中的应用。微动H/V谱比的本质为震动在不同岩土层结构中传播时垂直方向与水平方向的能量分配占比,通过5组实测微动信号的H/V谱比的结果分析,验证了H/V谱比法在岩土层探测领域的稳定性,即微动H/V谱比能够直接反映地下岩土层的结构变化。研究通过近似地质条件下的实例验证,建立了基岩埋深与H/V谱比最大峰值频率的拟合关系,拟合优度R^(2)均高于0.9,显著提升了土石分界面探测精度。结合H/V谱比剖面和速度剖面的联合解译,进一步提高了土石分界面探测结果的准确性。此外,在古城墙遗址探测中的应用案例表明,该方法对地下人工构筑物具有高灵敏度性,可有效识别地下构筑物及其背景地层。实践证实微动H/V谱比法具备现场操作简便、探测精度高、分辨率强等优势,为岩土工程勘察提供了高效、准确且对环境无干扰的技术手段,具有重要的推广价值。
基金supported by the Grant from the China Huadian Science and Technology Institute(CHDI.KJ-20)the National High-Tech Research and Development Program of China(863,2011AA03A405)
文摘The effect of synthesis methods on the activity of V/Ce/WTi catalysts was investigated for the selective catalytic reduction（SCR） of NO_x by NH_3. V/Ce/WTi-DP（deposition precipitation） catalyst showed excellent NH_3-SCR performance, especially the better medium-temperature activity and the less N_2O formation than V/Ce/WTi-IMP（impregnation）. These catalysts were characterized by X-ray diffraction（XRD）, Brumauer-Emmett-Teller（BET）, X-ray photoelectron spectroscopy（XPS）, temperature-programmed reduction（H_2-TPR）, and in situ DRIFTS techniques. The XPS and H_2-TPR results revealed that V/Ce/WTi-DP exhibited more surface Ce species, higher level of Oα and higher reducibility of Ce species. Reflected by in situ DRIFTS results, the deposition precipitation method（DP） contributed to a greater amount of weakly adsorbed NO_2, monodentate nitrate and NH_3 species with better reactive activity. Meanwhile, the cis-N_2O_2^（2-） species, an intermediate for N_2O formation, was very limited. As a result, these advantages brought about the superior SCR activity and N_2 selectivity for V/Ce/WTi-DP.
基金The rescarch was supported by the Doctoral Point Foundation of chinese Universities and NSF
文摘In this paper, an optimal V-cycle multigrid method for some conforming and nonconforming plate elements are constructed. A new method dealing with nonnested multigrid methods is presented.
基金supported by the Ministry of Education of China(No.208152)Gansu Natural Science Foundation(No.3ZS061-A52-47).
文摘Based on Zak＇s stress function, the eigen-equation of stress singularity ofbi-materials with a V-notch was obtained. A new definition of stress intensity factor for a perpendicular interfacial V-notch of bi-material was put forward. The effects of shear modulus and Poisson＇s ratio of the matrix material and attaching material on eigen-values were analyzed. A generalized expression for calculating/（i of the perpendicular V-notch of bi-materials was obtained by means of stress extrapolation. Effects of notch depth, notch angle and Poisson＇s ratio of materials on the singular stress field near the tip of the V-notch were analyzed systematically with numerical simulations. As an example, a finite plate with double edge notches under uniaxial uniform tension was calculated by the method presented and the influence of the notch angle and Poisson＇s ratio on the stress singularity near the tip of notch was obtained.
