结合2013年3月23-24日广西一次区域性强对流天气过程,运用常规观测资料、MICAPS实况资料和EC细网格数值预报资料计算准地转ω方程的两个主要强迫项:涡度平流的垂直差动项(简称"涡度平流项")和温度平流的拉普拉斯项(简称"...结合2013年3月23-24日广西一次区域性强对流天气过程,运用常规观测资料、MICAPS实况资料和EC细网格数值预报资料计算准地转ω方程的两个主要强迫项:涡度平流的垂直差动项(简称"涡度平流项")和温度平流的拉普拉斯项(简称"温度平流项")。结果表明,天气尺度的抬升运动主要是温度平流项的贡献,500 h Pa高空槽前的负变温造成了斜压性加强是抬升运动加强的主要原因,也是桂北强对流范围增大的主要原因。用ω方程结合数值预报回报的结果能较好地反映天气实况,说明上述方法在强对流天气预报中有一定的指导意义。展开更多
Applicability of the following creep constitutive equations was investigated for normal type creep curves of Ni-18.5Cr alloy and tertiary creep dominant curves of Ni-18.5Cr16W alloy under constant load: the θ project...Applicability of the following creep constitutive equations was investigated for normal type creep curves of Ni-18.5Cr alloy and tertiary creep dominant curves of Ni-18.5Cr16W alloy under constant load: the θ projection method describing a creep curse by a sum of two exponential terms, modified θ method describing a primary creep stage by an exponential term and a tertiary creep stage by a logarithmic term, modified Ω method describing a creep curve by a sum of two logarithmic term, 2θ method with only a tertiary creep component and Ω method. The θ, modified θ and modified Ω methods can describe normal type and tertiary creep dominant curves. Tertiary creep dominant curves of Ni-18.5Cr-16W alloy at 900℃ are also described using 2θ and Ω methods. Applicability of the modified θ and modified Ω methods is superior for constant load creep curves because they can predict creep curves up to rupture and rupture life accurately and conservatively.展开更多
In this paper we consider the numerical method of characteristics for the numerical solution of initial value problems (IVPs) for quasilinear hyperbolic Partial Differential Equations, as well as the difference scheme...In this paper we consider the numerical method of characteristics for the numerical solution of initial value problems (IVPs) for quasilinear hyperbolic Partial Differential Equations, as well as the difference scheme Central Time Central Space (CTCS), Crank-Nicolson scheme, ω scheme and the method of characteristics for the numerical solution of initial and boundary value prob-lems for the one-dimension homogeneous wave equation. The initial deriva-tive condition is approximated by different second order difference quotients in order to examine which gives more accurate numerical results. The local truncation error, consistency and stability of the difference schemes CTCS, Crank-Nicolson and ω are also considered.展开更多
An n × n ω-circulant matrix which has a specific structure is a type of important matrix. Several norm equalities and inequalities are proved for ω-circulant operator matrices with ω = e^(iθ)(0≤θ < 2π) ...An n × n ω-circulant matrix which has a specific structure is a type of important matrix. Several norm equalities and inequalities are proved for ω-circulant operator matrices with ω = e^(iθ)(0≤θ < 2π) in this paper. We give the special cases for norm equalities and inequalities, such as the usual operator norm and the Schatten p-norms. Pinching type inequality is also proposed for weakly unitarily invariant norms. Meanwhile,we present that the set of ω-circulant matrices with complex entries has an idempotent basis. Based on this basis, we introduce an automorphism on the ω-circulant algebra and then show different operators on linear vector space that are isomorphic to the ω-circulant algebra. The function properties, other idempotent bases and a linear involution are discussed for ω-circulant algebra. These results are closely related to the special structure of ω-circulant matrices.展开更多
文摘结合2013年3月23-24日广西一次区域性强对流天气过程,运用常规观测资料、MICAPS实况资料和EC细网格数值预报资料计算准地转ω方程的两个主要强迫项:涡度平流的垂直差动项(简称"涡度平流项")和温度平流的拉普拉斯项(简称"温度平流项")。结果表明,天气尺度的抬升运动主要是温度平流项的贡献,500 h Pa高空槽前的负变温造成了斜压性加强是抬升运动加强的主要原因,也是桂北强对流范围增大的主要原因。用ω方程结合数值预报回报的结果能较好地反映天气实况,说明上述方法在强对流天气预报中有一定的指导意义。
文摘Applicability of the following creep constitutive equations was investigated for normal type creep curves of Ni-18.5Cr alloy and tertiary creep dominant curves of Ni-18.5Cr16W alloy under constant load: the θ projection method describing a creep curse by a sum of two exponential terms, modified θ method describing a primary creep stage by an exponential term and a tertiary creep stage by a logarithmic term, modified Ω method describing a creep curve by a sum of two logarithmic term, 2θ method with only a tertiary creep component and Ω method. The θ, modified θ and modified Ω methods can describe normal type and tertiary creep dominant curves. Tertiary creep dominant curves of Ni-18.5Cr-16W alloy at 900℃ are also described using 2θ and Ω methods. Applicability of the modified θ and modified Ω methods is superior for constant load creep curves because they can predict creep curves up to rupture and rupture life accurately and conservatively.
文摘In this paper we consider the numerical method of characteristics for the numerical solution of initial value problems (IVPs) for quasilinear hyperbolic Partial Differential Equations, as well as the difference scheme Central Time Central Space (CTCS), Crank-Nicolson scheme, ω scheme and the method of characteristics for the numerical solution of initial and boundary value prob-lems for the one-dimension homogeneous wave equation. The initial deriva-tive condition is approximated by different second order difference quotients in order to examine which gives more accurate numerical results. The local truncation error, consistency and stability of the difference schemes CTCS, Crank-Nicolson and ω are also considered.
基金supported by National Natural Science Foundation of China(Grant Nos.11301251 and 11301252)the Applied Mathematics Enhancement Program of Linyi UniversityChina
文摘An n × n ω-circulant matrix which has a specific structure is a type of important matrix. Several norm equalities and inequalities are proved for ω-circulant operator matrices with ω = e^(iθ)(0≤θ < 2π) in this paper. We give the special cases for norm equalities and inequalities, such as the usual operator norm and the Schatten p-norms. Pinching type inequality is also proposed for weakly unitarily invariant norms. Meanwhile,we present that the set of ω-circulant matrices with complex entries has an idempotent basis. Based on this basis, we introduce an automorphism on the ω-circulant algebra and then show different operators on linear vector space that are isomorphic to the ω-circulant algebra. The function properties, other idempotent bases and a linear involution are discussed for ω-circulant algebra. These results are closely related to the special structure of ω-circulant matrices.
