一维自适应Kalman滤波的一种最优算法

1 引言 Kalman滤波是一种用于对含有随机摄动的动态系统的最优状态估值过程。更准确地讲,Kalman滤波器是一种从受噪声干扰的观测信号中,对被观测系统的状态进行统计估值的方法,这种估值是以线性、无偏、最小方差为准则的递推估值。它被广泛地应用于空间技术、雷达、导航、通信、工业自动化、气象和地震预报、生物医学工程等领域。 虽然Kalman滤波有许多成功的应用,但是从实用角度上看它仍有一些不足。众所周知,对于一个系统模型我们往往缺少对其真正特征的认识,即系统模型中常常含有未知的参数,而这一点将严重影响滤波器的工作。     

掺铥钨酸钡单晶生长和光谱研究

采用Czochralski 法生长出光学质量的BaWO₄:Tm³⁺单晶,利用X粉末衍射实验确定了不同掺杂浓度晶体的晶胞参数.测定了晶体的室温吸收光谱,应用Juud-Ofelt理论,拟合了光谱的3个强度参数,其值分别为Ω₂=404×10^-20cm²,Ω₄=0509×10^-20cm²,Ω关键词： 4：Tm³⁺单晶')" href="#">BaWO₄：Tm³⁺单晶 吸收谱 光谱参数 上转换发光     

Giant Birefringence of Lithium Niobate Crystals in the Terahertz Region

Terahertz time-domaln spectroscopy （THz-TDS） is used to study the spectral response of lithium niobate crystals （LiNbO3） in the far infrared region. The optical constants are derived from the measured complex refractive index. A giant birefringence is observed in this material, and the average refractive-index difference between the ordinary wave and the extraordinary wave, no - ne, can reach up to about 1.6. Such a large birefrlngence is attributed to the different p honon modes orAl（z） and E （ x , y ）. This unusual property makes LiNbO3 a promising material to be used as a functional material in the terahertz region, e.g. employed as wave-plates and polarization separators.     

一种基于空穴聚集的层裂模型

基于如下假设,给出了层裂过程中的应力松弛方程,并建立了一种基于空穴聚集的延性层裂模型：在层裂早期,微空穴的主要效应是减小应力作用面积;在层裂后期,应力按空穴聚集时的应力-空隙度依赖关系减小。把P.F.Thomason、D.L.Tonks等及S.Cochran等给出的依赖于应力（压力）的层裂空隙度方程分别耦合于守恒方程、计及损伤的状态方程及本构方程,建立了求解所有变量包括损伤的封闭方程组。这种基于空穴聚集的层裂模型已被应用于一维层裂试验的数值模拟。模型中的层裂强度及临界损伤度初始可以估计,最终的确定将使数值模拟结果与实测的速度（或应力）剖面以及观测的层裂面上的损伤基本一致。分别基于D.L.Tonk等及S.Cochran等给出的依赖于压力的层裂空隙度方程所作的一维层裂试验数值模拟结果基本一致,而与基于P.F.Thomason给出的依赖于应力的层裂空隙度方程所作的相应数值模拟结果有明显差异。     

Asymptotic solution of singular perturbation problems for the fourth-order elliptic differential equations

In this paper we consider the singularly perturbed boundary value problem for the fourth-order elliptic differential equation, establish the energy estimates of the solutionand its derivatives and construct the formal asymptotic solution by Lyuternik- Vishik ’s method.Finally, by means of the energy estimates we obtain the bound of the remainder of the asymptotic solution.     

Optimal selection for the weighted coefficients of the constrained variational problems

The aim is to put forward the optimal selecting of weights in variational problemin which the linear advection equation is used as constraint. The selection of the functionalweight coefficients ( FWC) is one of the key problems for the relevant research. It wasarbitrary and subjective to some extent presently. To overcome this difficulty, thereasonable assumptions were given for the observation field and analyzed field, variationalproblems with " weak constraints" and " strong constraints" were considered separately. Bysolving Euler' s equation with the matrix theory and the finite difference method of partialdifferential equation, the objective weight coefficients were obtained in the minimumvariance of the difference between the analyzed field and ideal field. Deduction results showthat theoretically the optimal selection indeed exists in the weighting factors of the costfunction in the means of the minimal variance between the analysis and ideal field in terms ofthe matrix theory and partial differen     

ON NUMERICAL SOLUTIONS OF PERIODICALLY PERTURBED CONSERVATIVE SYSTEMS

ＩｎｔｒｏｄｕｃｔｉｏｎＣｏｎｓｉｄｅｒｔｈｅｐｅｒｉｏｄｉｃｂｏｕｎｄａｒｙｖａｌｕｅｐｒｏｂｌｅｍｏｆｔｈｅｏｒｄｉｎａｒｙｄｉｆｆｅｒｅｎｔｉａｌｅｑｕａｔｉｏｎｓＬｕ≡ｕ″(ｔ) +ｇｒａｄＧ(ｕ) =ｐ(ｔ) ,ｕ( 0 ) =ｕ( 2π) ,ｕ′( 0 ) =ｕ′( 2π) ,( 1 )ｗｈｅｒｅｐ∈Ｃ(Ｒ ,Ｒｎ) ,Ｇ ∈Ｃ2 (Ｒｎ,Ｒ) .ＴｈｅｅｑｕａｔｉｏｎｍａｙｂｅｉｎｔｅｒｐｒｅｔｅｄａｓｔｈｅＮｅｗｔｏｎｉａｎｅｑｕａｔｉｏｎｏｆｍｏｔｉｏｎｏｆｔｈｅｍｅｃｈａｎｉｃａｌｓｙｓｔｅｍｓｕｂｊｅｃｔｔｏｃｏｎｓｅｒｖａｔｉ…     

Fully relativistic many-body perturbation energies,transition properties,and lifetimes of lithium-like iron Fe XXIV

Employing the advanced relativistic configuration interaction(RCI) combined with the many-body perturbation theory(RMBPT) method, we report energies and lifetime values for the lowest 35 energy levels from the(1s²)nl configurations(where the principal quantum number n = 2–6 and the angular quantum number l = 0,..., n-1) of lithium-like iron Fe XXIV, as well as complete data on the transition wavelengths, radiative rates, absorption oscillator strengths, and line strengths between the ...     

ON SOLVING PERIODIC BOUNDARY PROBLEM OF SEMILINEAR SYSTEMS WITH A ONE-PARAMETER IMBEDDING

The paper is concerned with solving periodic boundary problem of semilinear systems, which will be differentiably embedded into an one-parameter family of operators. The solution of the systems is then found by continuing the solution curve of operator homotopy. When the Newton-Kantorovich's procedure is applied to the cor     

C掺杂MgB2超导线材的失超特性研究

研究了不同芯数(单芯、6芯和12芯)的C掺杂MgB2超导线材的失超特性.在制冷机环境(20K)下测量了C掺杂MgB2超导线材样品在自场下的最小触发能及失超传播速度.实验结果表明,失超传播速度随着工作电流的增大而线性增加.失超传播速度的大小跟测量位置有关,离触发区越近的传播速度越大.单芯样品的最小触发能最小,6芯和12芯线的最小触发能相差不大.最小触发能随工作电流的增加成指数形式衰减.