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61.
讨论了构造Birkhoff表示的Hojman方法.利用该方法重新研究Birkhoff对称性,提出一种关于该对称性的新见解,给出Birkhoff守恒量的新证明,并对该守恒量仅与Birkhoff张量相关作出解释.举例说明所得结果的应用. 相似文献
62.
教学改革的最终目标都是为了有益于学生的全面发展以及实践能力的提高。以大学物理实验改革为例,介绍了"少台套大循环"的实验改革与教学管理方法。经过两年多"少台套大循环"的运行,这种改革不仅提高了学生的实验操作能力,而且在教学资源有效配置方面探索出一种可行的运行模式。 相似文献
63.
GM(1,1)模型灰色作用量的优化 总被引:1,自引:0,他引:1
通过把GM(1,1)模型中的灰色作用量b改进为动态的b_1+b_2k,从而构建了对灰色作用量优化的GM(1,1)模型.通过实例的验证以及与GM(1,1)模型对比,发现优化的GM(1,1)模型的模拟精度和预测精度均较高. 相似文献
64.
65.
R. Naz 《Applied mathematics and computation》2010,215(9):3265-3270
When two circular jets impinge upon each other along the axis of a hemi-spherical shell then a free jet on a hemi-spherical shell is formed. The governing equations are Prandtl’s momentum boundary layer equation and the continuity equation. The conserved quantity is required for the free jet on a hemi-spherical shell. The conserved quantity for the free jet on a hemi-spherical shell is established with the help of a conserved vector. The group invariant solution for the third-order partial differential equation for the stream function is constructed. 相似文献
66.
It is a business practice that home shopping companies offer a free trial period for their products with a goal of increasing sales. Under this policy, if for any reason customers are not satisfied with the purchase, they can return the product for a refund within the trial period. To develop inventory strategies in such environment, home shopping companies should take the return phenomenon into account so as to increase their profit. This paper considers this phenomenon and develops a seasonal inventory model to deal with the problem. Two scenarios are analyzed. In the first scenario, demand is assumed to be linearly price-dependent while in the second one, it is assumed to be exponentially price-dependent. The purpose of this research is to maximize the total profit over a given planning period by determining the optimal ordering quantity and price. The analytical results demonstrate that the optimal ordering quantity and prices are obtained using closed-form formulas. 相似文献
67.
By means of different concentrations the signal-to-noise ratios of Tc-99-NMR spectra were determined applying well measurable Tc-samples [tetrabutylammoniwn pertechnetate, TBA (TcO4)J and a 250 MHz-spectrometer. The signal-to-noise ratios of the spectra were determined by using the integrated routines of the firm's software and accumulating different number of scans. By fittings of data of the signal-to-noise ratio dependence and by extrapolation the minimum Tc-concentralion could be empirically found out. Applying a duration of measurements of 12 hours about 10?7 molar concentrations can be determined. 相似文献
68.
The ICH Q2(R1) (International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use) guideline for testing linearity in validation of analytical procedures suggests that “linearity should be evaluated by visual inspection of a plot of signals as a function of analyte concentration or content.” The EP6‐A guideline recommends more quantitative methods that compare straight‐line and higher‐order polynomial curve fits. In this paper, a new equivalence test is proposed to compare the quality of a straight‐line fit to that of a higher‐order polynomial. By using orthogonal polynomials and generalized pivotal quantity analysis, one may estimate the probability of equivalence between a straight line and a polynomial curve fit either in the assay signal space (the Y values) or in the concentration space (the X values). In the special case of the linear‐to‐quadratic polynomial comparison, an equivalence test may be constructed via a two one‐sided T test. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
69.
Jinn-Tsair Teng Hui-Ling Yang Maw-Sheng Chern 《Applied Mathematical Modelling》2013,37(14-15):7624-7632
During the growth stage of a product life cycle especially for high-tech products, the demand function increases with time. In this paper, we extend the constant demand to a linear non-decreasing demand function of time and incorporate a permissible delay in payment under two levels of trade credit into the model. The supplier offers a permissible delay linked to order quantity, and the retailer also provides a downstream trade credit period to its customers. The objective is to find the optimal replenishment cycle that minimizes the retailer’s annual total relevant cost per unit time. The condition for an optimal solution to the generalized model is presented and some fundamental theoretical results are established. Finally, numerical examples to illustrate the proposed model are provided. Sensitivity analysis is performed and some relevant managerial insights are obtained. 相似文献
70.
LIU Yang-Kui FANG Jian-Hui PANG Ting LIN Peng 《理论物理通讯》2008,50(9):603-606
Two new types of conserved quantities deduced by Noether-Mei symmetry of nonholonomic mechanical system are studied. The definition and criterion of Noether-Mei symmetry for the system are given. A coordination function is introduced, and the conditions under which the Noether-Mei symmetry leads to the two types of conserved quantities and the forms of the two types of conserved quantities are obtained. An illustrative example is given. The coordination function can be selected according to the demand for finding the gauge function, and the choice of the coordination function has multiformity, so more conserved quantities deduced from Noether-Mei symmetry of mechanical system can be obtained. 相似文献