Based on the analysis about the hydrogeological conditions and engineering geological conditions, this paper makes analysis on the possible risks of the deep overlying stratum foundation and establishes the risk evalu...Based on the analysis about the hydrogeological conditions and engineering geological conditions, this paper makes analysis on the possible risks of the deep overlying stratum foundation and establishes the risk evaluation index system during the foundation operating period. Such methods as analytic hierarchy process (AHP), Delphi method and fuzzy comprehensive evaluation method are adopted to make the quantitative analysis on the risk factors and establish the risk judgment model. According to the actual engineering of Taizhou Bridge, the paper evaluates the risk of the foundation during the operating period at the condition of deep overlying stratum. The evaluation results can provide the reference for the risk management of the bridge foundation during the operating period.展开更多
We observed an exchange bias effect in La0.5Ca0.5FeO3 perovskite compound.The exchange bias is associated with the charge disproportionation transition from Fe4+ions to Fe3+and Fe5+ions below 175 K.The competition bet...We observed an exchange bias effect in La0.5Ca0.5FeO3 perovskite compound.The exchange bias is associated with the charge disproportionation transition from Fe4+ions to Fe3+and Fe5+ions below 175 K.The competition between the ferromagnetic interaction of Fe3+and Fe5+ions and the antiferromagnetic one of Fe3+and Fe3+ions results in a unidirectional anisotropy in the cluster-glass system.An antiferromagnetically interfacial exchange coupling constant Ji1.95 meV at the cluster-glass region was yielded by fitting the cooling field-dependence of the exchange bias field.展开更多
In an excitable gas,the molecular vibration relaxation process caused by an acoustic disturbance leads the equilibrium heat capacity to the effective one that depends on the acoustic frequency,resulting in acoustic di...In an excitable gas,the molecular vibration relaxation process caused by an acoustic disturbance leads the equilibrium heat capacity to the effective one that depends on the acoustic frequency,resulting in acoustic dispersion and acoustic relaxational absorption.Based on the algorithm of synthesizing a single-relaxation process,we develop a synthesizing method to get the equilibrium heat capacities of excitable gases from the two-frequency acoustic speed and absorption measurements.The two measurement frequencies are selected in the range where the acoustic relaxational absorption is obvious.The method can obtain the heat capacities of internal and external degrees of freedom of gas molecules respectively,and effectively eliminate the influence of the acoustic relaxation process on the measurement results of excitable gas heat capacity.For various gases,consisting of CO2,CH4,Cl2,N2 and O2 at room temperature,the gas heat capacities obtained in this paper agree with the thermodynamic theoretical calculations based on the Planck-Einstein formula,and the maximum relative error is 3.51% in comparison to the experimental result.The synthesized heat capacities of rotation and vibration can be applied to the detection of gas molecular geometry,vibration frequency and mole fractions of gas mixtures.展开更多
To research the correlation between vibrational energy transition rates and acoustic relaxation processes in excitable gases, the vibrational relaxation theory provided by Tanczos [J. Chem. Phy3. 25, 439 （1956）] is ...To research the correlation between vibrational energy transition rates and acoustic relaxation processes in excitable gases, the vibrational relaxation theory provided by Tanczos [J. Chem. Phy3. 25, 439 （1956）] is applied to calculate the energy transition rates of Vibrational- Vibrational （V-V） and Vibrational-Translational （V-T） energy transfer in gas mixtures. The results of calculation for the multi-relaxation processes in various gas mixtures, consisting of carbon dioxide, methane, chlorine, nitrogen, and oxygen at room temperature, demonstrate that the acoustic energy stagnated in every vibrational mode is coupled with each other through V-V energy exchanges. The vibrational excitation energy will relax through the V-T de-excitation path of the lowest mode because of its fastest V-T transition rate, resulting in that only one absorption peak can be measured for most of excitable gas mixtures. Thus, an effective model is provided to analyze how the vibrational energy transition rates affect the characteristics of acoustic relaxation processes and acoustic propagation in excitable gas mixtures.展开更多
基金National Science and Technology Support Program of China(No.2009BAG15B02)Key Programs for Science and Technology Development of Chinese Transportation Industry(No.2008-353-332-180)
文摘Based on the analysis about the hydrogeological conditions and engineering geological conditions, this paper makes analysis on the possible risks of the deep overlying stratum foundation and establishes the risk evaluation index system during the foundation operating period. Such methods as analytic hierarchy process (AHP), Delphi method and fuzzy comprehensive evaluation method are adopted to make the quantitative analysis on the risk factors and establish the risk judgment model. According to the actual engineering of Taizhou Bridge, the paper evaluates the risk of the foundation during the operating period at the condition of deep overlying stratum. The evaluation results can provide the reference for the risk management of the bridge foundation during the operating period.
基金supported by the National Basic Research Program of Chinathe National Natural Sciences Foundation of China(Grant No.11205015)+1 种基金the Natural Sciences Foundation of Beijing(Grant No.1113017)Beijing Area Logistics System&Technology Major Laboratory and the Logistics Management and Engineering Innovation Platform of Beijing Wuzi University
文摘We observed an exchange bias effect in La0.5Ca0.5FeO3 perovskite compound.The exchange bias is associated with the charge disproportionation transition from Fe4+ions to Fe3+and Fe5+ions below 175 K.The competition between the ferromagnetic interaction of Fe3+and Fe5+ions and the antiferromagnetic one of Fe3+and Fe3+ions results in a unidirectional anisotropy in the cluster-glass system.An antiferromagnetically interfacial exchange coupling constant Ji1.95 meV at the cluster-glass region was yielded by fitting the cooling field-dependence of the exchange bias field.
基金supported by the National Natural Science Foundation of China(61461008,61571201,11764007,51465009)the Natural Science Foundation of Guizhou Province,China([2015]2065)+1 种基金the Key Research Project for Colleges and Universities of Henan Province,China(15A510037)the Recruitment Program of Guizhou Institute of Technology(XJGC20140601)
文摘In an excitable gas,the molecular vibration relaxation process caused by an acoustic disturbance leads the equilibrium heat capacity to the effective one that depends on the acoustic frequency,resulting in acoustic dispersion and acoustic relaxational absorption.Based on the algorithm of synthesizing a single-relaxation process,we develop a synthesizing method to get the equilibrium heat capacities of excitable gases from the two-frequency acoustic speed and absorption measurements.The two measurement frequencies are selected in the range where the acoustic relaxational absorption is obvious.The method can obtain the heat capacities of internal and external degrees of freedom of gas molecules respectively,and effectively eliminate the influence of the acoustic relaxation process on the measurement results of excitable gas heat capacity.For various gases,consisting of CO2,CH4,Cl2,N2 and O2 at room temperature,the gas heat capacities obtained in this paper agree with the thermodynamic theoretical calculations based on the Planck-Einstein formula,and the maximum relative error is 3.51% in comparison to the experimental result.The synthesized heat capacities of rotation and vibration can be applied to the detection of gas molecular geometry,vibration frequency and mole fractions of gas mixtures.
基金supported by the National Natural Science Foundation of China(61461008,61371139,61571201,61540051)the China Scholarship Council Project(201708525058)+1 种基金the National Science Foundation of Guizhou Province,China(Qian Ke He J Zi[2015]2065),Qian Ke He LH Zi[2014]7361)the Recruitment Program of Guizhou Institute of Technology(XJGC20140601,XJGC20150107)
文摘To research the correlation between vibrational energy transition rates and acoustic relaxation processes in excitable gases, the vibrational relaxation theory provided by Tanczos [J. Chem. Phy3. 25, 439 （1956）] is applied to calculate the energy transition rates of Vibrational- Vibrational （V-V） and Vibrational-Translational （V-T） energy transfer in gas mixtures. The results of calculation for the multi-relaxation processes in various gas mixtures, consisting of carbon dioxide, methane, chlorine, nitrogen, and oxygen at room temperature, demonstrate that the acoustic energy stagnated in every vibrational mode is coupled with each other through V-V energy exchanges. The vibrational excitation energy will relax through the V-T de-excitation path of the lowest mode because of its fastest V-T transition rate, resulting in that only one absorption peak can be measured for most of excitable gas mixtures. Thus, an effective model is provided to analyze how the vibrational energy transition rates affect the characteristics of acoustic relaxation processes and acoustic propagation in excitable gas mixtures.
