查询词典 approximation methods in physics

Firstly, this paper investigated roundly the basic theory of the ambient vibration method, analyzed systematically the main methods of ambient vibration identification, and discussed their advantages and disadvantages. Then we established the finite element model of structural dynamics and test model and analyzed their mutual relation, improved MUSIC method and correlation function method in the harmonic identification, and gave the subspace method and correlation function method based on continuous model, which is multi-harmonic retrieve technique. And then, this paper also puts forward least-squares method to estimate directly structural physical and modal parameters; this approach replaced the derivative operator in the continuous time model with an equivalent approximation, and estimated the physical parameters of structures by the least-squares method. And then, we discussed the approximation methods of derivative and their convergence. Finally, this paper researched the modal parameters of a frame structure by the simulation and test. The results demonstrated that subspace method, correlation function method and the least-squares method are effective and stable respectively.

全面地研究环境振动识别方法的基本理论，系统地分析环境振动识别方法的主要方法，讨论它们的优点和不足；建立结(来源：6666AB44C论文网www.abclunwen.com)构动力学的有限元模型和试验模型，分析有限元模型与试验模型之间的相互关系；改进谐波识别中的MUSIC识别方法和相关函数识别方法，给出大型结构模态识别的连续型的子空间分解识别方法和相关函数识别方法，这个方法是多元谐波识别方法；提出直接识别结构的物理参数和模态参数的最小二乘方法，这个方法利用导数的近似值代替导数值，并运用最小二乘方法识别结构的物理参数，讨论导数近似值的选择方法，分析算法的收敛性；通过仿真计算和模型实验，研究高层框架结构的模态参数识别，验证子空间分解识别方法、相关函数识别方法和最小二乘识别方法的有效性，算法的稳定性；从理论和试验两个方面分析和研究噪声对识别精度的影响，影响识别精度的因素，以及部分模态成分的模态参数不能够被识别的原因。

One position control system is introduced as the objective controlled by FOC. Based on Mittag-Leffler function, the fractional order control system with full memory length is adopted as evaluation criterion, and an approximation performance function of discretization methods is proposed. Analyzing the time domain error and approximation performance, the investigation to various discretization methods is carried out comparatively in detail.

引入一个位置控制系统作为分数阶控制对象，将Mittag-Leffler函数的全记忆长度分数阶控制系统作为评估基准，提出了一种离散算法的近似性能函数，通过时域误差分析以及近似性能分析，对比研究了分数阶微积分算子的数字实现方法。

In order to reasonably depict four basic problems with friction, one Coulomb friction new form in first Kirchhoff stress is proposed to deal with finite deformation problems, other Coulomb friction form in incremental mode to elastoplastic flow theory; Hilbert function spaces concerning elastoplastical problems with friction are established, so it makes all operations and calculations in the treatise standardized within the scope of reasonably topologic structure; In view of functional extremum, the equivalence between generalized variational inequalities principles in elastoplasticity with friction and corresponding basic problems are testified by inducing Lagrangian multipliers, so it provides a rationally theoretical basis for numerical methods in elastoplasticity with friction; From the viewpoint of variational inequality, the theory of generalized variational inequalities in elasticity and elastoplasticity with frictional constraint is studied, and the uniqueness and existence of the solution of FEM is proofed under the proposed conditions of stress compatibility, and them FEM approximation and a discrete solution are discussed; Based on the principles of generalized variational inequalities in elastoplasticity with friction, direct generalized variational inequalities methods is pretended, which is a natural generalization and development of direct variational methods; Using generalized variational inequalities methods, some examples in metal forming including plane deformation, upset and extrusion are analyzed and the results prove that all the theories and methods in the paper are right, feasible, accurate and advanced.

主要内容有：为了合理地描述金属塑性成形中摩擦约束弹性、弹塑性基本问题，提出和研究了有限变形下以Kirchhoff第一应力表示的Coulomb摩擦定律形式和弹塑性流动理论下以增量形式表示的Coulomb摩擦定律表示形式；系统建立了摩擦约束弹塑性问题的Hilbert函数空间，使本文规范在一个具有合理的代数拓扑结构内进行一切操作和运算；利用Lagrange乘子，从泛函极值的角度系统地阐述和论证了一系列摩擦约束弹性、弹塑性广义变分不等原理与相应的实际问题之间的等价性，它为处理摩擦约束的弹塑性力学数值方法提供了合理的理论基础；从变分不等式的角度出发，阐述了对应于摩擦约束弹性、弹塑性问题的广义变分不等式理论，首次提出了在应力相容性条件下，它的有限元解具有存在唯一性，进而讨论了其有限元近似及离散解法；基于摩擦约束弹塑性广义变分不等式原理，首次提出了直接广义变分不等式方法，这一方法是直接变分法的合理推广和发展；利用直接广义变分不等式方法对金属压力加工中的平面变形问题、镦粗、挤压等塑性成形问题进行了分析计算，验证了该理论和数值算法的正确性、实用性、精确性和优越性。

The modern physics development by to the concrete material embodiment inspection, moved towards to the abstract material abstract research, namely from specially moves towards general, its utilizes the mathematical instrument is also same, moves towards mathematics from physical mathematics physics, already developed the abstract algebra and the general analysis situs, from bad on the one hand said, the physicist because of lost the concrete material object to change confusedly, was at a loss how to proceed, from was good on the one hand says, the research technique from specially moved towards general, also caused its thinking mode to have the return, tended to the philosophy, this speaking of the physics, was one kind of significant crisis, but at the same time, Also is a brand-new development turning point.

现代物理学的发展已由对具体物质的具象考察，走向对抽象物质的抽象研究，即从特殊走向一般，其所运用的数学工具也一样，从物理的数学走向数学的物理，已经发展到抽象代数和一般拓扑学，从坏的一方面讲，物理学家因失去了具体的物质对象而变得迷茫，无所适从，从好的一方面讲，研究方法的从特殊走向一般，也使其思维方式发生了回归，趋向于哲学，这对物理学而言，是一种重大危机，但与此同时，也是一个全新的发展契机。

Chapter two, the theoretical basic of the metacongnition in Physics, stating that the theory of Autobus instructive study and the theory of architectural study, Piaget basic constructional learning theory and Vygotsky Social Construction are the psychological base of the metacongnition in Physics teaching, while Lifelong Education Theory and the Theoretical Research of the Subjectivity Education are the pedagogy basic of the metacongnition in Physics teaching.

第二章是元认知物理教学的理论基础。阐明了元认知的基本理论，奥苏伯尔的有意义学习理论、以及皮亚杰的建构主义学习理论和维果斯基社会建构理论是元认知物理教学的心理学基础，终身教育理论、主体教育理论是元认知物理教学的教育学基础。

The academic content of this meeting will be: elementary particles and astrophysics, coacervation physics, new materials, applied physics, nuclear physics and synchronized radiation technology, etc.

大会学术内容为基本粒子和天体物理、凝聚态物理、新材料、应用物理、核物理及同步辐射技术等。

Physics concepts, theorems as well as principles are primary content of physics learning, those knowledge take on the forms by proposition . In chapter 3, the study revealed that physics proposition are mainly obtained by reasoning (inductive reasoning such as tallying method, differentiation method and covariant method, deductive reasoning such as negative expression of hypothetical inference, affirmative expression of hypothetical inference ).Then by the means of experiment, the different condition needed when applying those reasoning was explored.

由于定义性概念、定理和定律等命题知识是物理教学的主要内容，所以在第三章中首先通过研究，表明物理命题主要是运用推理策略获得的(归纳推理策略中的求同策略、差异策略和共变策略，演绎推理策略)；然后通过实验等方法研究使用策略需要的条件；最后依据前面的研究提出适合物理命题学习的任务分析方法。

Nobel physics award is the world's accepted physics top prize, can say the imperial crown that is physics kingdom.

诺贝尔物理学奖是世界公认的物理学最高奖项，可以说是物理学王国的皇冠。

The spread of the periodic wave, the advantage and disadvantage of the solid dynamic theory, the orderly system and the disorderly system physics; It also discuss the classification of the phase transformation and the division between the quantum method and the classical method in the condensed matter physics; and also point out the major developing trend of the present condensed matter physics.

对周期波的传播、固体能带理论的优缺点以及有序体系和无序体系的物理学；相变分类、凝聚态物理中量子方法与经典方法的界定进行了讨论，并指出了凝聚态物理发展的主要方向。

Want to active galactic nuclei have an in-depth, comprehensive study, to be integrated black hole physics, relativity, quantum physics, magnetohydrodynamics and plasma physics, and many other aspects of knowledge.

要对活动星系核有一深入、完整的研究，必须综合黑洞物理学、相对论、量子物理学、磁流体力学和等离子体物理学等诸多的方面知识。

"Second Life is remarkably easy to work with, and is very popular,"

"第二次生命是显着容易的工作，并且很受欢迎，"

For example, we usually assume that materials are homogeneous and isotropic and free of internal defects or flaws.

为了得到适合有限元分析的模型，我们必须经过如图2所示的简化步骤。