条件方程

We analyze formers centers conditions for polynomial Lienard equations, give direct conditions of a nondegenerate center at the origin with elimination theory, and give an algorithm for general situations with algebraic elimination methods of polynomials.

运用多项式的代数消元法，对前人给出的多项式Liénard方程的中心判据进行分析，对多项式的系数给出原点是非退化中心的直接条件，并对较一般的情形给出算法。

MethodsBy means of orthogonally rotational combination design, microwave extraction mathematical simulation model was concluded by the linear regression analysis. In order to obtain the optimum extraction of flavonoids, the regression equation of the relationship between the four factors were established.

方法通过二次回归正交旋转组合试验设计，得到了微波提取苦丁茶中黄酮的数学回归方程；利用模型的响应曲面图及等高线图，对影响微波提取苦丁茶黄酮提取率的关键因素及相互作用进行探讨，得到最佳提取工艺条件。

Especially, it is found that there exists three types of relative permeability of water such as concave, convex to the water saturation ax and the reversed "S" pattern. The super-low permeability reservoir is sensitive to pressure, apparent with millipore undersaturation and water blocks. In this study, a new concept of irriducible undersaturation is brought up. And a new mode to describle the process of imbibition dynamics is used to reveal and confirm the mechanism of pinhole enveloping macropore as following: pendular ring of wetting phase gathers→it fills throat→it truncates nonwejting phase . The expression of pressure distribution and the equation of oil production are deduced under conditions of non-darcy linear seepage and non-linear seepage.

尤其发现水相相对渗透率曲线存在凹向、凸向含水饱和度轴及反S形三种形式；特低渗透储层的压力敏感性强，微孔隙的欠饱和及水锁效应显著，本文研究中提出欠束缚水饱和度的概念，引用一种描述渗吸动态即湿相液环聚集→充填喉道→截断非湿相的演化过程的新方法，更深刻地揭示和证明了&小孔包围大孔&机理；推导出了非达西线性渗流和非线性渗流条件下的压力分布表达式和油井产量方程。

Based on Born approximationmethod and the local principles of wave function in inhomogeneous medium and theray theory and the integral equation theory,this dissertation researches the theory andsimulation of the inversion method of large perturbational medium parameters andbreaks through the approximation condition of the small perturbational parametersand the weak scattering in traditional inversion method.

本文在Born近似方法的基础之上，基于非均匀介质中波函数局部理论和射线理论及积分方程等理论方法，对大扰动参数反演方法的理论和数值模拟进行了研究，突破了传统反演方法要求的参数小扰动和弱散射条件。

CFD-fluent simulation software and measurement are applied to establish the math models of exhaust gas concentration distribution and boundary conditions. Finite volume methods and PISO are used to solve the differential equations of exhaust gas distribution in a kitchen. After the adjustment and comparison with those from the practical measure, the simulation results of CO2 and CO concentration distributions accord with experimental ones.

运用CFD-fluent模拟软件和实测相结合的方法，建立废气的浓度和扩散分布的数学模型与边界条件，利用数值分析法中的有限体积法和PISO算法对厨房内废气分布的微分方程进行离散和求解，对模拟结果进行校正并与实际测试结果进行比较。

Based on the source terms and fusion burn-up equations,a three-temperature plasma model is founded in which the electrons,ions,and the radiation filed are represented by separate temperatureskT_e,kT_i and kT_r,respectively,where kT_r is characterized by a Planckian distribution.

第四章建立了考虑α粒子慢化的两温模型和三温模型，首先导出了考虑慢化的α粒子对等离子体的能源项，替换已有的两温模型的等离子体能量密度方程中的能源项，将其改进为考虑α粒子慢化过程的两温模型，与瞬时沉积能量的两温模型作了对比，在不同的初始温度密度条件下考察了α粒子慢化对等离子体聚变燃烧的影响。

With Platycodon root as experiment material, on the base of single factor experiments (extraction time, extraction temperature and so on), then through the experimental design of response surface methology, the conditions of extraction are studied.

以桔梗为实验材料，在提取温度、提取时间、料液比等单因素实验的基础上，利用响应曲面实验设计法对桔梗皂甙提取条件进行研究，并通过回归方程和响应曲面，得到了最佳提取工艺。

MethodsIn the solvent of 1 mol/L NaOH, using the reaction of the water-soluble phenolic acidity in Radix Salviae Miltiorrhizae and the NaNO_2-Al(NO_3)_3, the total components of water-soluble phenolic acidity in Radix Salviae Miltiorrhizae injections and drip solution(calculated with protocatechualdehyde) were determined by colorimetric s...

方法利用丹参中水溶性酚酸类成分与亚硝酸钠和硝酸铝溶液在碱性条件下的显色反应，比色法测定该两种制剂中水溶性酚酸的总量。结果原儿茶醛在3.336~14.46mg/L范围内呈良好的线性关系，回归方程为：A=0.02777C+0.01279(r=0.9996)，加样平均回收率为100.8%，RSD为0.96%。结论该法简便快速，结果准确，重现性好，可用于该制剂的质量控制。

Chapter 4 of this dissertation has carried out a physical simulation study about the processes of formation and laws of evolution of the fan delta in Baimiao gas field. Based on the results of the study about the geological background in this area, this paper has discussed about the sedimentation facies marks for the fan delta in Baimiao gas field, worked out a detailed proposal about the development of physical simulation experiment about the fan delta, and described in detail the general laws and major controlling factors governing the sedimentation processes of the fan delta. A detailed measurement was made about the experimental results, and a systematic comparison was made relative to the prototypic characteristics. Based on the observation and description about the experimental processes and the analyses about the experimental results, this paper has give

在本章中，指出了数值模拟研究的基本特点，给出了扇三角洲形成过程的基本控制方程和数学解法：在此基础上设计和开发了扇三角洲形回成过程的平面二维数值模拟软件，并对计算过程中所遇到的主要问题一计算速度较慢开展研究，对比了以天、旬、月为时间单元进行汁算对沉积结果的影响，研究认为，在流量无突变的情况下，可以适当增长计算的时间步长和适当放松精度要求；根据白庙气田扇三角洲的基本地质特征设计了数值模拟计算的基本条件，以月为单位，计算了扇三角洲四百年的形成过程及演化规律，并以50年为单位输出沉积结果；本章最后还对数值模拟方法及结果进行了讨论。

In this paper include: Successfully using iterative analysis method get some pulsive delay differential equations and sufficient condition of the existence,uniqueness and stablility of their solutions.

本文主要工作包括：利用迭代分析方法很成功地获得了某类脉冲和时滞微分方程解的存在性和唯一性，以及其解稳定的充分条件。

The split between the two groups can hardly be papered over.

这两个团体间的分歧难以掩饰。

This approach not only encourages a greater number of responses, but minimizes the likelihood of stale groupthink.

这种做法不仅鼓励了更多的反应，而且减少跟风的可能性。