共查询到19条相似文献,搜索用时 109 毫秒
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研究小干扰力作用下约束哈密顿系统对称性的摄动问题.建立了非保守约束哈密顿系统的正则方程,在增广相空间中研究了系统的对称性与精确不变量.基于力学系统的高阶绝热不变量的概念,给出了系统的各阶绝热不变量的形式及存在条件,并建立了绝热不变量与对称变换之间的对应关系
关键词:
约束哈密顿系统
对称性
摄动
不变量 相似文献
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对有心力场中的行星轨迹问题,通过建立以复数矢量为变量的方程进行求解.在求解过程中不仅得到了行星运动的一般性规律,还推导出行星的速度公式和哈密顿定理,同时发现行星轨道的第二焦点位置及基于拉普拉斯-隆格-楞次矢量的轨迹方程,并由此求出不同方向发射卫星的轨迹包络线. 相似文献
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将电磁波导的控制方程导向了Hamilton体系、辛几何的形式.以电磁场的横向分量组成对偶向量并采用分离变量法,可以得到Hamilton算子矩阵的辛本征值问题.共轭辛正交归一关系、辛本征解展开定理等均可在此应用.对于复杂横截面和填充非均匀材料的电磁波导,提出对偶棱边元,对截面半解析离散后即可进行数值求解.对偶棱边元克服了结点基有限元求解电磁场问题的困难,与常规棱边元相比在某些方面具有一定的优势.
关键词:
电磁波导
Hamilton体系
对偶变量
棱边元 相似文献
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燃气轮机仿真模型是燃气轮机控制策略研究与验证的重要工具,对燃气轮机控制系统国产化研制与替代具有重要作用。本文针对某型燃气轮机特性提出了一种基于迁移学习的燃气轮机机理建模方法,制定了燃气轮机部件特性线迁移变换策略,建立了燃气轮机部件特性迁移学习模型,并采用优化算法求解获得了迁移系数矩阵,最后利用迁移系数矩阵建立了燃气轮机动态仿真模型。以某9F燃气轮机现场运行数据进行了迁移学习模型训练和验证,并进行了燃气轮机动态模型仿真测试,结果表明,利用已知燃气轮机部件特性和极少量目标燃气轮机运行数据,即可建立较高精度的目标燃气轮机动态仿真模型,模型关键参数平均相对误差在1.6%以下,可以用于控制策略研究与验证。 相似文献
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《Journal of Geometry and Physics》2006,56(10):1985-2009
Using Fedosov’s approach we give a geometric construction of a formal symplectic groupoid over any Poisson manifold endowed with a torsion-free Poisson contravariant connection. In the case of Kähler–Poisson manifolds this construction provides, in particular, the formal symplectic groupoids with separation of variables. We show that the dual of a semisimple Lie algebra does not admit torsion-free Poisson contravariant connections. 相似文献
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The duality solution for elasticity and the biorthogonality relationship have been well researched. Now the couple stress
theory becomes a new research spot but there is few research for the biorthogonality relationship for couple stress theory
comparing to classical elasticity. A new state vector is presented for three dimensional couple stress problems of prismatic
structures. A new biorthogonality relationship of couple stress is discovered. The dual partial differential equations of
couple stress problem are derived by the new state vector. By two important identical equations the new biorthogonality relationship
is proved based on the method of separation of variables. The symplectic orthogonality relationship to three dimensional couple
stress theory may be decomposed into two independently and symmetrically orthogonality relationships. The new biorthogonality
relationship includes the symplectic orthogonality relationship. The biorthogonality relationship of couple stress may also
be degenerated into the theory of elasticity. The new state vector and biorthogonality relationship provide theoretic foundation
for the research on the schemes of separation of variables and eigenfunction expansion of couple stress theory. 相似文献
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We show that the evolution equations for a perfect fluid coupled to general relativity in a general lapse and shift, are Hamiltonian relative to a certain Poisson structure. For the fluid variables, a Lie-Poisson structure associated to the dual of a semi-direct product Lie algebra is used, while the bracket for the gravitational variables has the usual canonical symplectic structure. The evolution is governed by a Hamiltonian which is equivalent to that obtained from a canonical analysis. The relationship of our Hamiltonian structure with other approaches in the literature, such as Clebsch potentials, Lagrangian to Eulerian transformations, and its use in clarifying linearization stability, are discussed.Research supported in part by NSF grant MCS 81-08814(A02)Research supported in part by NSF grant MCS 81-07086 相似文献
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The present paper deals with the natural vibration of thin circular and annular plates using Hamiltonian approach. It is based on the conservation principle of mixed energy and is constructed in a new symplectic space. A set of Hamiltonian dual equations with derivatives with respect to the radial coordinate on one side of the equations and to the angular coordinate on the other side are obtained by using the variational principle of mixed energy. The separation of variables is employed to solve Hamiltonian dual equations of eigenvalue problem. Analytical frequency equations are obtained based on different cases of boundary conditions. The natural frequencies are the roots of the frequency equations and corresponding mode functions are in terms of the dual variables q1(r, θ). Three basic edge-constraint cases for circular plates and nine edge-constraint cases for annular plates are calculated and the results are compared well with existing ones. 相似文献
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《Heat Recovery Systems and CHP》1991,11(6):517-521
Decrease of fuel supplies and cost increases make it vital for industries, especially energy intensive ones, to consider conserving available sources and convert losses into sources of energy.In this paper, a gas turbine-based cogeneration system is suggested to utilize a refinery's reformer gas in the gas turbine, and furnaces flue gases together with the engine exhaust gases in a heat recovery steam generator, HRSG. This is proposed as an alternative to the currently used system where the gas turbine and the steam generator are used separately. Operating variables comprising compressor pressure ratio and turbine inlet temperature are varied widely to evaluate performance; namely power, SFC, overall efficiency and annual fuel savings at design and off-design loading conditions using a dedicated computer program.Results show that the proposed system offers 100% higher overall efficiency and $5.25 million annual fuel saving for a 12 MWe gas turbine. 相似文献
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《Heat Recovery Systems and CHP》1994,14(4):365-376
A scheme is described for the recovery of waste heat from stacks of gas turbine engines and the utilization of recovered energy for the cooling of ambient air. Relationships are summarized for the modeling of components of the cooling system. Samples are presented from performance data that is predicted by the model. Effect of size and design of system components, as well as operational variables on system performance, are discussed. It is concluded that the single most significant variable in the design of the looped heat-pipe recovery and utilization system is the geometry of the exhaust pipe of the gas turbine engine. Accordingly it is suggested that a design for the exhaust pipe of a gas turbine must consider the effects of (a) the variation of velocity of exhaust gases at different exhaust inlet temperatures, and the consequent pressure drops in the exhaust chimney pipe, and (b) the length of the exhaust pipe. The latter essentially determines the length of the heat pipe evaporator. Furthermore, the temperature drop through the air cooler is also significant, since this also influences system performance. 相似文献