In this study, we introduce a system of differential equations describing the motion of a single point mass or of two interacting point masses on a surface, that is solved by a fourth-order explicit Runge–Kutta(RK4) ...In this study, we introduce a system of differential equations describing the motion of a single point mass or of two interacting point masses on a surface, that is solved by a fourth-order explicit Runge–Kutta(RK4) scheme. The forces acting on the masses are gravity, the reaction force of the surface, friction, and, in case of two masses, their mutual interaction force. This latter is introduced by imposing that the geometrical distance between the coupled masses is constant. The solution is computed under the assumption that the point masses strictly slide on the surface, without leaping or rolling. To avoid complications stemming from numerical errors related to real topographies that are only known over discrete grids, we restrict our attention to simulations on analytical continuous surfaces. This study sets the basis for a generalization to more complex systems of masses, such as chains or matrices of blocks that are often used to model complex processes such as landslides and rockfalls. The results shown in this paper provide a background for a companion paper in which the system of equations is generalized, and different geometries are presented.展开更多
The real-time computer-controlled actuators are used to connect the truncated parts of moorings and risers in the active hybrid model testing system. This must be able to work in model-scale real time, based on feedba...The real-time computer-controlled actuators are used to connect the truncated parts of moorings and risers in the active hybrid model testing system. This must be able to work in model-scale real time, based on feedback input from the floater motions. Thus, mooring line dynamics and damping effects are artificially simulated in real time, based on a computer-based model of the problem. In consideration of the nonlinear characteristics of the sea platform catenary mooring line, the equations of the mooring line motion are formulated by using the lumped-mass method and the dynamic response of several points on the mooring line is investigated by the time and frequency domain analysis method. The dynamic response of the representative point on the mooring line is analyzed under the condition of two different corresponding upper endpoint movements namely sine wave excitation and random wave excitation. The corresponding laws of the dynamic response between the equivalent water depth truncated points at different locations and the upper endpoint are obtained, which can provide technical support for further study of the active hybrid model test.展开更多
The wavelet approach is introduced to study the influence of the natural convection stagnation point flow of the Williamson fluid in the presence of thermophysical and Brownian motion effects. The thermal radiation ef...The wavelet approach is introduced to study the influence of the natural convection stagnation point flow of the Williamson fluid in the presence of thermophysical and Brownian motion effects. The thermal radiation effects are considered along a permeable stretching surface. The nonlinear problem is simulated numerically by using a novel algorithm based upon the Chebyshev wavelets. It is noticed that the velocity of the Williamson fluid increases for assisting flow cases while decreases for opposing flow cases when the unsteadiness and suction parameters increase, and the magnetic effect on the velocity increases for opposing flow cases while decreases for assisting flow cases. When the thermal radiation parameter, the Dufour number, and Williamson’s fluid parameter increase, the temperature increases for both assisting and opposing flow cases. Meanwhile, the temperature decreases when the Prandtl number increases. The concentration decreases when the Soret parameter increases, while increases when the Schmidt number increases. It is perceived that the assisting force decreases more than the opposing force. The findings endorse the credibility of the proposed algorithm, and could be extended to other nonlinear problems with complex nature.展开更多
本文研究了新型惯质调谐质量阻尼器(novel tuned mass damper inerter,NTMDI)的安装方法对其优化设计与减振性能的影响。详细介绍了NTMDI-R(反向安装的NTMDI)的力学模型,并采用经典固定点理论对NTMDI-R进行了优化设计,得到了NTMDI-R最...本文研究了新型惯质调谐质量阻尼器(novel tuned mass damper inerter,NTMDI)的安装方法对其优化设计与减振性能的影响。详细介绍了NTMDI-R(反向安装的NTMDI)的力学模型,并采用经典固定点理论对NTMDI-R进行了优化设计,得到了NTMDI-R最优结构参数的解析式;对比研究了NTMDI-R与现有四种经典调谐质量阻尼器(TMD、TMDI、VTMD和NTMDI)在简谐激励和随机激励下的减振效果,并探究了安装方法对NTMDI-R减振性能的影响。结果表明:正、反向安装的两种减振器(NTMDI和NTMDI-R)优化参数不同,安装方法对其减振性能有较大影响。当表观质量比β小于0.1时,NTMDI-R的减振效果差于NTMDI;而β大于0.1时,NTMDI-R的减振效果与NTMDI基本一致,因此采用NTMDI进行结构减振应明确其安装方向。基础加速度和荷载力分别作用下,NTMDI-R的减振效果相对于NTMDI分别降低了3.9%和4.7%。展开更多
目的 建立一测多评(quantitative analysis of multi-components by single marker, QAMS)法同时测定穿心莲中9种成分含量的分析方法。方法 采用超高效液相色谱-串联质谱法,以穿心莲内酯为内参物,建立该成分与连翘苷、齐墩果酸、咖啡酸...目的 建立一测多评(quantitative analysis of multi-components by single marker, QAMS)法同时测定穿心莲中9种成分含量的分析方法。方法 采用超高效液相色谱-串联质谱法,以穿心莲内酯为内参物,建立该成分与连翘苷、齐墩果酸、咖啡酸、穿心莲内酯、脱水穿心莲内酯、穿心莲新酯、去氧穿心莲内酯、脱水穿心莲内酯琥珀酸半酯、亚硫酸氢钠穿心莲内脂的相对校正因子,利用相对校正因子来计算各成分的含量,同时将QAMS法计算结果和外标法实测值进行比较。结果 相对校正因子重现性良好,使用QAMS法与外标法所测得的结果无明显的差异。结论 QAMS法适用于穿心莲中9种成分的同时测定,以保证质量的可靠性。展开更多
复系数质点法是以几何点的运算为基础而建立起来的一种新的几何定理机器证明方法.它能高效地证明大部分构造型几何命题,但现有的复系数质点法仍不能有效地处理一些非线性构造型几何命题.为此,该文在原有工作的基础上,对原复系数质点法...复系数质点法是以几何点的运算为基础而建立起来的一种新的几何定理机器证明方法.它能高效地证明大部分构造型几何命题,但现有的复系数质点法仍不能有效地处理一些非线性构造型几何命题.为此,该文在原有工作的基础上,对原复系数质点法机器证明算法进行了较大的改进,新添加了一些重要的构图方式,并选用Mathematica重新实现了改进的算法,创建了新的证明器CMPP(Complex Mass Point method Prover).对上百个几何定理的运行结果显示,证明器CMPP能有效地处理非线性构造型几何命题以及许多非构造型几何命题,在解题能力及运行效率上均有所提高.特别地,CMPP能在短时间内实现五圆定理、莫莱定理等一些难度较大的几何定理的可读机器证明.展开更多
基金mostly financed by the FP7 Project ASTARTE "Assessment,Strategy and Risk Reduction for 740 Tsunamis in Europe"(FP7-ENV2013 6.4-3,Grant603839)the Italian National Project RITMARE that,among others,treat landslide models with tsunamigenic potential
文摘In this study, we introduce a system of differential equations describing the motion of a single point mass or of two interacting point masses on a surface, that is solved by a fourth-order explicit Runge–Kutta(RK4) scheme. The forces acting on the masses are gravity, the reaction force of the surface, friction, and, in case of two masses, their mutual interaction force. This latter is introduced by imposing that the geometrical distance between the coupled masses is constant. The solution is computed under the assumption that the point masses strictly slide on the surface, without leaping or rolling. To avoid complications stemming from numerical errors related to real topographies that are only known over discrete grids, we restrict our attention to simulations on analytical continuous surfaces. This study sets the basis for a generalization to more complex systems of masses, such as chains or matrices of blocks that are often used to model complex processes such as landslides and rockfalls. The results shown in this paper provide a background for a companion paper in which the system of equations is generalized, and different geometries are presented.
基金financially supported by the Natural Science Foundation of Zhejiang Province(Grant Nos.Y14E090034 and Y13F020140)the Young Scientist Training Program in Zhejiang Province(Grant No.2013R60G7160040)+1 种基金the State Key Laboratory of Ocean Engineering of Shanghai Jiao Tong University for the Open Fund Project(Grant No.1516)the Open Fund Project of Second Institute of Oceanography(Grant No.SOED1706)
文摘The real-time computer-controlled actuators are used to connect the truncated parts of moorings and risers in the active hybrid model testing system. This must be able to work in model-scale real time, based on feedback input from the floater motions. Thus, mooring line dynamics and damping effects are artificially simulated in real time, based on a computer-based model of the problem. In consideration of the nonlinear characteristics of the sea platform catenary mooring line, the equations of the mooring line motion are formulated by using the lumped-mass method and the dynamic response of several points on the mooring line is investigated by the time and frequency domain analysis method. The dynamic response of the representative point on the mooring line is analyzed under the condition of two different corresponding upper endpoint movements namely sine wave excitation and random wave excitation. The corresponding laws of the dynamic response between the equivalent water depth truncated points at different locations and the upper endpoint are obtained, which can provide technical support for further study of the active hybrid model test.
基金Project supported by the National Natural Science Foundation of China(Nos.51709191,51706149,and 51606130)the Key Laboratory of Advanced Reactor Engineering and Safety,Ministry of Education of China(No.ARES-2018-10)the State Key Laboratory of Hydraulics and Mountain River Engineering of Sichuan University of China(No.Skhl1803)
文摘The wavelet approach is introduced to study the influence of the natural convection stagnation point flow of the Williamson fluid in the presence of thermophysical and Brownian motion effects. The thermal radiation effects are considered along a permeable stretching surface. The nonlinear problem is simulated numerically by using a novel algorithm based upon the Chebyshev wavelets. It is noticed that the velocity of the Williamson fluid increases for assisting flow cases while decreases for opposing flow cases when the unsteadiness and suction parameters increase, and the magnetic effect on the velocity increases for opposing flow cases while decreases for assisting flow cases. When the thermal radiation parameter, the Dufour number, and Williamson’s fluid parameter increase, the temperature increases for both assisting and opposing flow cases. Meanwhile, the temperature decreases when the Prandtl number increases. The concentration decreases when the Soret parameter increases, while increases when the Schmidt number increases. It is perceived that the assisting force decreases more than the opposing force. The findings endorse the credibility of the proposed algorithm, and could be extended to other nonlinear problems with complex nature.
文摘本文研究了新型惯质调谐质量阻尼器(novel tuned mass damper inerter,NTMDI)的安装方法对其优化设计与减振性能的影响。详细介绍了NTMDI-R(反向安装的NTMDI)的力学模型,并采用经典固定点理论对NTMDI-R进行了优化设计,得到了NTMDI-R最优结构参数的解析式;对比研究了NTMDI-R与现有四种经典调谐质量阻尼器(TMD、TMDI、VTMD和NTMDI)在简谐激励和随机激励下的减振效果,并探究了安装方法对NTMDI-R减振性能的影响。结果表明:正、反向安装的两种减振器(NTMDI和NTMDI-R)优化参数不同,安装方法对其减振性能有较大影响。当表观质量比β小于0.1时,NTMDI-R的减振效果差于NTMDI;而β大于0.1时,NTMDI-R的减振效果与NTMDI基本一致,因此采用NTMDI进行结构减振应明确其安装方向。基础加速度和荷载力分别作用下,NTMDI-R的减振效果相对于NTMDI分别降低了3.9%和4.7%。
文摘目的 建立一测多评(quantitative analysis of multi-components by single marker, QAMS)法同时测定穿心莲中9种成分含量的分析方法。方法 采用超高效液相色谱-串联质谱法,以穿心莲内酯为内参物,建立该成分与连翘苷、齐墩果酸、咖啡酸、穿心莲内酯、脱水穿心莲内酯、穿心莲新酯、去氧穿心莲内酯、脱水穿心莲内酯琥珀酸半酯、亚硫酸氢钠穿心莲内脂的相对校正因子,利用相对校正因子来计算各成分的含量,同时将QAMS法计算结果和外标法实测值进行比较。结果 相对校正因子重现性良好,使用QAMS法与外标法所测得的结果无明显的差异。结论 QAMS法适用于穿心莲中9种成分的同时测定,以保证质量的可靠性。
文摘复系数质点法是以几何点的运算为基础而建立起来的一种新的几何定理机器证明方法.它能高效地证明大部分构造型几何命题,但现有的复系数质点法仍不能有效地处理一些非线性构造型几何命题.为此,该文在原有工作的基础上,对原复系数质点法机器证明算法进行了较大的改进,新添加了一些重要的构图方式,并选用Mathematica重新实现了改进的算法,创建了新的证明器CMPP(Complex Mass Point method Prover).对上百个几何定理的运行结果显示,证明器CMPP能有效地处理非线性构造型几何命题以及许多非构造型几何命题,在解题能力及运行效率上均有所提高.特别地,CMPP能在短时间内实现五圆定理、莫莱定理等一些难度较大的几何定理的可读机器证明.
