差分法

First the traditional non-optical detection technology for gas concentrations is briefly introduced, such as ultra-sound technology, gas sensing, catalytic thermal, gas chromatography, interferometry applications, and then the spectral analysis based on the concentration of gas detection is discussed. The latest technological developments on the differential absorption spectroscopy, Fourier transform infrared spectroscopy, tunable laser diode laser absorption spectroscopy, laser radar and differential absorption Raman scattering laser radar, laser-induced fluorescence spectroscopy, laser Photoacoustic Spectroscopy are reviewed in detail.

首先对传统的非光学气体浓度检测技术作出了简单的介绍，包括超声波技术、气敏法、热催化法、气相色谱法、干涉法应用技术，被动检气管法，然后重点阐述了基于光谱学分析气体浓度检测技术的最新发展动态，其中分别对差分吸收光谱技术、傅里叶变换红外光谱技术、可调谐激光二极管激光吸收光谱技术、差分吸收激光雷达和拉曼散射激光雷达、激光诱导荧光光谱技术、激光光声光谱技术进行了详细介绍，最后提出了现代气体浓度检测技术的发展方向。

This makes more and more people pay more attention to studies and applications of numerical simulation in thermal recovery. In this research, we have developed a reliable mathematical model for thermal recovery, which takes a full consideration of the effect of viscos, gravitical and capillary forces on the three-phase flow of gas, water and oil, the effect of the temperature on the medium characteristics of liquid and solid, the phase equilibrium of gas-liquid in each component, heat transportation including connection, conduction and radiation as well as heat losses in both the overburn and underlying strata. In the space discreation of the mathematical model, we have proposed a new method based on the improvement of the conventional nine-points difference approximation, which has a higher difference accurancy.

本项研究以热力采油的主要机理为基础，充分考虑在粘性力、重力和毛管力作用下油水气三相流动，考虑温度对各种流体和固体介质物性的影响，考虑每一组分中汽液两相的相平衡，考虑热在地层中的传导、对流和辐射以及上下盖层的热损失，利用热力学第一定律、质量守恒定律和流体迁移定律，建立了正确可靠的注蒸汽数学模型；在对数学模型进行空间离散时，利用控制有限体积积分法，对以往的九点差分近似作了合理的改进，使其具有较高的差分近似精度：结果表明，该公式的近似精度要比以往文献中所给的九点差分近似精度高，可以认为，在油藏数值模拟中，如果遇到非均质情况，使用这种九点差分近似更合理。

After explaining correlation theory and its important features, the rescaled range analysis、modified rescaled range analysis and detrended fluctuation analysis are analysed. As for the drawbacks produced by the rescaled range analysis when faced with short term correlation, a modified rescaled range analysis based on short term correlation model is applied to Shanghai stock market and Shenzhen stock market. The result is explained and compared.

在阐述了分形时间序列的相关理论和重要特征后，对经典重标极差分析法、修正重标极差分析法和趋势消解波动分析法等一维分形分析方法进行了系统分析，针对重标极差分析法对短期相关会产生有偏结果的缺点，给出了一种基于短期相关的改进的重标极差分析法，把各种一维分形分析方法应用于上证综合指数和深圳成分指数序列进行实证分析，并对结果进行了比较和解释。

This course is an attempt to give the students the basic idea and method of forest management in order to prepare the management plan; Place of forest management in forestry; Content of forest management; Guide principles of forest management; Sustained working; Silvicultural system; Forest yield; Increment; Volume increment; Quality increment; Price increment; Total price increment; Forest maturity; Indicating percent; Productive stage; Physical rotation; Technical rotation; Rotation of maximum volume yield; Highest forest rent rotation; Financial rotation; Cutting cycle of selection system; Normal forest; Normal distribution of age classes; Normal arrangement of stands; Normal increment; Normal growing stock; Normal yield; Improvement of actual forest; Reserve forest; Reserve fund; Planning and plan of forest management; Forest regulation; Area allotment; Volume allotting method; Volume frame work; Area-volume combined frame work; Growing stock; Utilization percent method; Difference method; Pure age-class; Growth method; Control method; Forest subdivision; Forest surveying; Forest survey; Certainty of future policy of forest; Selection of species; Decision of silvicultural system; Decision of rotation; Regulation of future yield; Preparation of management plan; Working the plan; Control and revision of management

本课程之目的为使学生了解森林经营之基本观念及方法，以期编订经营计划，课程包括森林经营学在林学上之地位、森林经营学之内容、森林经营之指导原则、保续作业、森林作业法、森林收获、生长、材积生长、形质生长、腾贵生长、总价格生长、林木成熟期、指率、生产期、自然轮伐期、工艺轮伐期、材积收获最多轮伐期、森林纯益最大之轮伐期、财政轮伐期、择伐林之回归期、法正林、法正龄级分配、法正林分排列、法正生长、法正蓄积、法正伐采额、现时林之改良、预备林、预备金、森林经营上之规划及计划、收获预定、面积配分法、材积配分法、材积平分法、折衷平分法、蓄积法、利用率法、较差法、纯粹龄级法、生长量法、稽核法、森林区划、森林测量、森林调查、将来森林经营方针之确定、树种之选定、作业法之决定、轮伐期之判定、将来收获之预定、经营管理计划之编订、计划之执行、经营管理计划之稽核与检订。

The model is solved using finite difference method. The profiles of water saturation, pore pressure and gas pressure were plotted.

采用有限差分法对所建模型进行了求解，并绘制了含水饱和度、孔隙水压力和孔隙气压力的时空分布曲线。

The distribution of thickness rolled and profile are simulated by considering roll system elastic deformation theory, distributions of tension stresses theory and roll thermal crown theory during rolling of wide strip and high speed aluminum foil roughing mill the rolling technology and thermochemistry parameters are tested, etc, the paper verifies above theories.

采用差分法模拟了具有分段冷却装置的宽幅高速铝箔粗轧机轧辊的温度场及热凸度分布。对轧辊热形为特性进行了全面的研究。首次考虑铝箔轧制的辊系弹性变形理论。张应力分布理论及轧辊热变形理论模拟了宽幅高速铝箔粗轧机的轧后断面形状及板形。

We calculated resonance spectrum and resonance mode profiles of the DQPC twin and triple-cavity by 3D finite-difference time-domain method.

利用三维有限时域差分法我们可以计算准光子晶体二重以及三重共振腔中的共振场图和模态图。

With the Finite-Difference Time-Domain method, the characteristic of electromagnetic field within the vacant resonant cavity was analyzed.

采用时域有限差分法数值求解Maxwell方程，分析了MPT无加载谐振腔内的电磁场特性。

On the basis of it, the cascade flow field with endwall suction, the effects of suction on the different endwall locations (such as near the leading-edge, in the middle of the passage or near the suction surface) on the development of secondary flow, the distributions of total pressure loss coefficient and yaw angle are investigated respectively.

本文首先采用三维稳态时均N—S方程组的有限体积差分法及压力修正算法数值求解技术对一直列透平静叶栅通道内流动的发展进行了模拟，利用文献中的实验结果验证了计算方法与程序的适用性。

It was presented that a dynamic retrieving differential equation mode of two-variable hydrologic time series considering one main cycle.

3提出一种考虑一个主周期的水文二元时间序列动力反演微分方程模式，并应用双向差分法和最小二乘法推导微分方程参数，给出求解公式。

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。