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输送流体管道振动Housner方程的修正 总被引:3,自引:2,他引:1
本既考虑了流体速度对管道的诱发振动,又考虑了振动的管道对流体的反馈影响,推出输送流体管道振动微分方程的准确形式,并指出Housner方程是近似的。 相似文献
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卡尔曼滤波在光纤监测中的应用 总被引:1,自引:0,他引:1
薛毅,杨中华.卡尔曼滤波在光纤监测中的应用.本文提出用卡尔曼滤波方法对光纤的接口位置进行确定。该方法的优点是:可以自动地、较为准确地得到光纤的接口位置,为光纤监测数据的自动分析提供了依据 相似文献
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在复数的运算(变形)过程中,除了准确运用有关运算法则外,如能善于捕捉式子的结构特征,恰当地辅之以相关的运算变形技巧,将有助于快速、简捷、准确地解决问题. 本文主要介绍复数运算与变形过程中的5种基本方法. 1.提取.即根据有关式子中各项之间、各因子之间或分子、分母之间的特征及内在联系,灵活提取复数±1、ω或提取常数因子,使之利于运用 i、ω的性质或(1± i)2=± 2i,或出现约去公因子、消项的机会. 2.取模.即根据解题需要,灵活地对一个复数或方程两边“取模”,继而利用复数模的有关公式或性质,使复数… 相似文献
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“咬文嚼字”一般形容过分地斟酌字句,多指死扣字眼而不注意精神实质.数学语言是一门特殊的语言,具有准确性、规范性和通用性的特点,是数学思维的最佳载体.如果语言领会到位、思维严谨的话,就能准确地理解题意,得出正确的解决方法.反之,如果理解不到位,就会产生理解的偏差,导致解题方法的不得当,得出错误的结果.所以,有时候在数学中“咬文嚼字”的精神也值得提倡,善于挖掘关键字词的含义,才能理解到位,准确无误. 相似文献
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建于上世纪七八十年代的油气管道运行了近40年,在役管道中约60%服役时间超过20年,进入事故多发期。对于大量新老管线,在不同程度上存在着未融合、气孔、裂纹、腐蚀等引起应力集中等缺陷。目前的内检测手段难以有效发现这类缺陷,并且受到许多清管条件的限制。油气管道弱磁力层析无损检测技术不受现场检测条件限制,可直接对新建和长期运行的铁磁性管道进行上述缺陷检测,根据缺陷异常等级针对性地提出维修建议,预防管道穿孔、开裂等事故的发生,从而提高油气管道安全运行能力与完整性管理水平。建立铁磁构件应力集中区的力磁耦合模型,可以定性预测缺陷的分布、深度以及应力对磁信号的影响。在理论基础上,利用研发的弱磁信号采集仪对燃气管道进行了检测,准确地查找出了埋地燃气管道的穿孔位置。 相似文献
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本文研究不可压缩可导流体沿一均匀磁场中的椭圆管道的流动.在Hartmann数是充分大的情形下,应用多重尺度法,作出解的准确到任意量级的渐近近似式.本方法可用于研究截面具有光滑周界的,任意形状管道的磁流体动力流. 相似文献
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《Applied Mathematical Modelling》2014,38(7-8):2141-2150
Zou et al. (2008) [21] presented weighted-average of all possible choice values approach of soft sets under incomplete information system in decision making. However, the approach is hard to understand and involves a great amount of computation. In order to simplify the approach, we present the simplified probability to directly instead of the incomplete information, and demonstrate the equivalence between the weighted-average of all possible choice values approach and the simplified probability approach. Finally, comparison results show that the proposed approach involves relatively less computation and is easier to implement and understand as compared with the weighted-average of all possible choice values approach. 相似文献
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In this paper, a finite element recovery approach is proposed to improve the accuracy of finite element approximations for Green’s functions in three dimensions. This recovery approach is based on some simple postprocessing. It is proved by both theory and numerics that the recovery approach is very efficient. In particular, the approach is successfully applied to some electrostatic potential computations. 相似文献
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In this paper, a novel approach, namely, the linearization‐based approach of homotopy analysis method, to analytically treat non‐linear time‐fractional PDEs is proposed. The presented approach suggests a new optimized structure of the homotopy series solution based on a linear approximation of the non‐linear problem. A comparative study between the proposed approach and standard homotopy analysis approach is illustrated by solving two examples involving non‐linear time‐fractional parabolic PDEs. The performed numerical simulations demonstrate that the linearization‐based approach reduces the computational complexity and improves the performance of the homotopy analysis method. 相似文献
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Yu. G. Rykov 《Proceedings of the Steklov Institute of Mathematics》2018,301(1):213-227
The paper contains results concerning the development of a new approach to the proof of existence theorems for generalized solutions to systems of quasilinear conservation laws. This approach is based on reducing the search for a generalized solution to analyzing extremal properties of a certain set of functionals and is referred to as a variational approach. The definition of a generalized solution can be naturally reformulated in terms of the existence of critical points for a set of functionals, which is convenient within the approach proposed. The variational representation of generalized solutions, which was earlier known for Hopf-type equations, is generalized to systems of quasilinear conservation laws. The extremal properties of the functionals corresponding to systems of conservation laws are described within the variational approach, and a strategy for proving the existence theorem is outlined. In conclusion, it is shown that the variational approach can be generalized to the two-dimensional case. 相似文献
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Production scheduling and maintenance planning have interdependencies but been often considered and optimized independently in practice and in the literature. Furthermore, product quality has direct relationship with maintenance planning. This paper proposes an integrated approach for production scheduling and maintenance planning for parallel machine system considering the effect of cost of rejection. The approach aims to determine optimal production schedule and maintenance plan such that overall operations cost is minimized. A simulation-based optimization approach is used to solve the problem. A numerical investigation is performed to illustrate the approach. The integrated approach shows between 0.6 and 35.8% improvement in term of overall operations cost over independent approach for various scenarios. The results indicate that simultaneous consideration of production scheduling and maintenance planning results into better system performance. 相似文献
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This paper considers the pricing of contingent claims using an approach developed and used in insurance pricing. The approach is of interest and significance because of the increased integration of insurance and financial markets and also because insurance-related risks are trading in financial markets as a result of securitization and new contracts on futures exchanges. This approach uses probability distortion functions as the dual of the utility functions used in financial theory. The pricing formula is the same as the Black-Scholes formula for contingent claims when the underlying asset price is log-normal. The paper compares the probability distortion function approach with that based on financial theory. The theory underlying the approaches is set out and limitations on the use of the insurance-based approach are illustrated. The probability distortion approach is extended to the pricing of contingent claims for more general assumptions than those used for Black-Scholes option pricing. 相似文献
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Nizami A. Gasilov Şahin Emrah Amrahov 《Mathematical Methods in the Applied Sciences》2020,43(4):1825-1837
In this study, a new approach is developed to solve the initial value problem for interval linear differential equations. In the considered problem, the coefficients and the initial values are constant intervals. In the developed approach, there is no need to define a derivative for interval-valued functions. All derivatives used in the approach are classical derivatives of real functions. The reason for this is that the solution of the problem is defined as a bunch of real functions. Such a solution concept is compatible also with the robust stability concept. Sufficient conditions are provided for the solution to be expressed analytically. In addition, on a numerical example, the solution obtained by the proposed approach is compared with the solution obtained by the generalized Hukuhara differentiability. It is shown that the proposed approach gives a new type of solution. The main advantage of the proposed approach is that the solution to the considered interval initial value problem exists and is unique, as in the real case. 相似文献
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Ranking of fuzzy numbers play an important role in decision making, optimization and forecasting etc. Fuzzy numbers must be
ranked before an action is taken by a decision maker. In this paper, with the help of several counter examples, it is proved
that ranking method proposed by Chen and Chen (Expert Systems with Applications 36 (3): 6833) is incorrect. The main aim of
this paper is to propose a new approach for the ranking of generalized trapezoidal fuzzy numbers. The proposed ranking approach
is based on rank and mode so it is named as an RM approach. The main advantage of the proposed approach is that the proposed
approach provides the correct ordering of generalized and normal trapezoidal fuzzy numbers and also the proposed approach
is very simple and easy to apply in the real life problems. It is shown that proposed ranking function satisfies all the reasonable
properties of fuzzy quantities proposed by Wang and Kerre (Fuzzy Sets and Systems 118 (3): 375). 相似文献
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王延源 《数学的实践与认识》2006,36(3):212-216
Chew Soo Hong,Zheng Q uan提出了一个积分——水平集求全局最优的概念性算法及M on te-C ar-lo随机投点的实现途径,并在很多实际问题中得到了很好的应用,但这一实现算法的收敛性是个未解决的问题.利用近年来广泛应用的遗传算法,给出了这一算法的另一种实现途径,并从理论和数值两个方面验证了算法的可行性. 相似文献