second-order accuracy 中文意思是什麼
second-order accuracy
解釋
二階精度-
In order to detect the bottom thickness, cavity, leak and deformation of steel meshes in secondary lining of concrete in tunnel construction, the authors evaluate the wave character and the detected result in the second lining of the tunnel using surveying radar technology and conclude the wave character in the tunnel lining which has mass defect and tested the accuracy and reliability of this technique
摘要為檢明隧道混凝土二次襯砌中的底界厚度、空洞、漏水、鋼筋網變形等質量問題，利用探地雷達技術，通過對檢測方法及工程檢測實驗的研究，進行隧道二次襯砌中雷達波形特徵參數及檢測結果評價，總結了隧道襯砌質量問題的雷達波形特徵，驗證檢測方法的精度和可靠性。 -
In this paper, a crank - nicolson mixed element method, a nonlinear galerkin mixed element method for the non stationary conduction - convection problems time second order accuracy fully discrete formats and a two - level mixed element method with backtracing for the stationary conduction - convection problems are presented and analyed, respectively, an error analysis are provided for the crank - nicolson method of time discretization applied to spatially discrete galerkin mixed element approximations of the nonstationary conduction - convection problems
本文分別給出了非定常的熱傳導-對流問題的crank - nicolson混合元法時間二階精度全離散格式，非線性galerkin混合元法時間二階精度全離散格式以及定常的熱傳導-對流問題回溯二重水平法。討論了時間上的crank - nicolson離散方法應用於非定常的熱傳導-對流問題的空間離散的galerkin混合元近似。 -
In this paper, we expand eigenvalue of poisson equation using bilinear element, by the formulation of the error expanition, we can conclude that it is a upper bound. and by two numerical example, we computer the approximate eigenvalue of poisson equation in square and l - shape domains, then we analyses the approximate eigenvalue. we also extraplate the error expansion and enhance the accuracy of the eigenvalue form the second order to the forth order
本論文對poisson方程的特徵值採用雙線性元進行展開，得到了誤差展開式，通過誤差展開式，我們能得到特徵值是上界。通過數值算例，計算方形與l形區域上的poisson方程的近似特徵值，並對數據進行分析，驗證了理論的正確性，然後通過對誤差展開式外推，收斂級數可以從二階提高到四階，得到了高精度的解。 -
The conformal microstrip antenna with some unique character has been applied in many fields, especialy on speedy objects. in this paper, an efficient fdtd algorithm is introduced to analyse the microstrip antenna. firstly, the fdtd formula in descartes coordinate system and in cylindrical coordinate system are obtained from the time _ dependent maxwell equations using the yee algorithm in a calculating region where the dielectric parameters are independent of time and space. the choice of the space discretization units and the time discretization interval are discussed which are decided by the accuracy and stability respectively. the shape and setup of the excitation source are discussed too. the excitation source is chosen to be gaussian pulse in shape. secondly, the mur ' s first - order and second - order boundary condition are deduced in cylindrical coordinate system. the methods of transforming radiation fields from near zone to far zone in the frequency domain and in the time domain are presented when fdtd is applied to analyse the characteristics of far zone. finally, three kinds of microstrip antennas are analysed. they are a slot antenna that lies on a plane ground of a microstrip, a slot antenna that lies on a cylindrical ground of a microstrip and a microstrip line _ fed aperture coupled stacked rectangular patch antenna in cylindrical coordinate system
本文從麥克斯韋旋度方程出發，建立了笛卡兒坐標下無源空間中均勻無耗媒質的fdtd基本方程和圓柱坐標下無源空間中均勻無耗媒質的fdtd基本方程，詳細討論了fdtd法計算中時間步長和空間步長的選取原則以及激勵源的類型和設置；推導了mur一階和二階邊界條件在圓柱坐標下的差分格式；給出了在用fdtd法計算天線的遠場輻射特性時必需採用的頻域和時域近場遠場變換技術；最後用fdtd法計算了平面微帶縫隙天線、柱面共形微帶縫隙天線和柱面共形微帶層疊天線的輸入阻抗和遠區輻射場，並分析了天線的一些參數的變化對天線輸入阻抗的影響，得出了一些有用的結論。 -
3. the modeling method based on mechanism analysis and identification method always exits unmodeled high - order part and the modeling method based on neural networks usually has not good enough generalization capability. we fuse above two kinds of modeling method and put forward a hybrid modeling method based on mechanism analysis, identification and rbf neural networks. this paper proposed a hybr id modeling method based on mechanism analysis, identification and rbf neural networks. first, get a object ' s low - order model by the mechanism analysis and identification method. second, adopt rbf neural networks modeling method to compensate unmodeled high - order model. the sum of the low - order model and high - order model is the hybrid model. this kind of hybrid model has more accuracy than a model based on mechanism analysis and identification and has more generalization capability than a model based on neural networks
針對基於機理分析和辨識的建模方法總是存在未建模的高階部分，精度不夠高和神經網路建模方法泛化能力差的缺點，將這兩種建模方法進行融合，提出基於機理分析、系統辨識和rbf神經網路的混合建模方法，首先採用機理分析和辨識的方法得到工業對象的低階模型，再用rbf神經網路建模方法補償未建模高階模型，這樣得到的混合模型，比單純基於機理分析和辨識的建模方法具有更高的精度，比單純的神經網路的建模方法具有更好的泛化能力。 -
The details of the construction and characteristics of the new finite - difference scheme are presented in this thesis, by using both the integration theorem and the taylor expansion theory. it is proved that the new approach has the second - order accuracy on the grids with axis - symmetric voronoi cells and at least has the first - order accuracy in general. according to this character of the scheme and the computational requirements of the finite - difference approach, a striping procedure is involved to decompose the velocity model into variable spatial size grids with a nearly constant tune step preserved
本文從積分定理和taylor展開兩個角度，詳細分析了基於voronoicell的非規則網格有限差分演算法的構造過程及性質，並且在理論上證明了本文的差分方法的精度與網格形狀的關系：當voronoicell為關于節點的軸對稱圖形時，本文差分方法具有二階精度；在一般的網格上，則至少具有一階精度。 -
Different results specify that the first kind of cost function is sensitive to the mismatch of ocean depth and receiver location, but is insensitive to sound speed profile ' s % $ jai8x9 @ t $ m & z mismatch and has high accuracy of depth localizaion ; the second kind of cost fimction is insensitive to all three kinds of mismatch, but its resolution of depth is very low ln order to overcome the cost function ' s sensitivity to mismatch, improvemedt of the accuracy of time delay estimation and model calculation may be adopted, when both conditions are reached, the sensitivity wiil be greatly reduced and the resolution of range and depth will be improved at the same time
模擬結果表明，第一類代價函數對海底深度和基陣傾斜失配是敏感的，對聲速失配卻不敏感，並且能夠獲得較高的深度定位精度；第二類代價函數對三種失配都不敏感，只是深度解析度較低。為了克服代價函數對失配的敏感性，可採用提高時延估計精度和模型計算精度的方法。當兩個條件滿足時，敏感性得到極大的抑制並獲得了較高的距離和深度估計精度。 -
Non - oscillatory and non - free - parameters dissipative ( nnd ) finite difference scheme ( a total variation diminishing scheme ) with second order accuracy was adopted to solve the fluid dynamic equations, a finite rate chemical reaction model was developed to calculate ingredient producing rate, and an adi over relaxation iteration technique was used to solve the electromagnetic discretized equations
採用二階精度nnd格式求解流體力學方程組，採用有限速率化學反應模型計算組分生成率，採用交替方向隱式（ adi ）超鬆弛迭代法求解電磁場離散方程。 -
We also extrapolate the expansion arid enhance the accuracy of the eigenvalue from the second order to the fourth order
然後對誤差展開式外推，收斂階數可以從二階提高到四階，得到了高精度的解。 -
We expand the eigenvalue of possion equation using wilson nonconforming element. by the formulation of the error expanition, we can not conclude whether it is a upper bound or a lowr bound. but we guess it is a lower bound, and by two numerical example, we find thatwe are right. we also extraplate the error expansion and enhance the accuracy of the eigenvalue from second order to third order
通過數值算例，計算方行與l行區域上的poisson方程的近似特徵值，並對數據進行分析，驗證了我們的推測是正確的，然後通過對誤差展開式外推，收斂階數可以從二階提高到三階，得到了高精度的解。 -
The resulting optimized - frequency diagnosis algorithm, based on the second - order sensitivity, helps get a solution with better accuracy. when the tolerances of normal components are ignored and partly ignored, experiment results show that the accuracy of solutions, compared to the first - order sensitivity, is improved and is further improved via combining the improved genetic algorithm with the second - order sensitivity diagnosis method
模擬實驗表明:在不考慮正常元件容差和考慮部分正常元件容差兩種情況下，和一階靈敏度故障診斷方法相比較，二階靈敏度故障診斷方法的精度得到了顯著的改善，並且改進遺傳演算法的引入能使故障診斷方程的求解精度獲得進一步的提高。 -
Thus the second - order diagnosis equations are introduced. it is necessary to propose the second - order sensitivity with higher accuracy than first - order sensitivity, although the basic thought and sensitivity matrix analysis approach, similar to the first - order sensitivity, are used
盡管採用了相似於一階靈敏度故障診斷方法的基本思想和靈敏度矩陣分析方法，但是由於二階靈敏度故障診斷方程比一階靈敏度故障診斷方程具有更高的精度，因此引入二階靈敏度是必要的。 -
Efficiency and accuracy of stability - guaranteed second - order difference scheme in full - multigrid method
問題的二階混合差分法 -
Solutions are advanced in time by explicit four - stage runge - kutta integration with up to second - order temporal accuracy. to avoid grid motion induced error, the geometric conservation law ( gcl ) is satisfied numerically
為避免網格運動給數值解帶來額外誤差，給出了幾何守恆律的離散形式並在數值上滿足了幾何守恆律條件。 -
On the basis of some conclusion, we have proved that the schemes have second - order convergence accuracy for the time discretization, a two - level method for resolving the nonlinearity in finite element approximation of the stationary conduction - convection problems is presented
在某些已有結論的基礎之上，我們證明了這種格式對于時間離散上的二階精度。提出了一種解決定常的熱傳導-對流問題的有限元近似中出現的非線性問題的兩層方法。 -
Abstract : in this paper, the authors study the initial value problems of a class of weakly nonlinear differential equation. the first and the second order approximate solutions are obtained. their accuracies are high and the more the approximate order is high, the more the accuracy is high. if the regular perturbation method is used to solve the same problems, then, when the independent variable is big, so is the error of the solution
文摘:用插值攝動法1研究一類弱非線性常微分方程的初值問題，得到了一級及二級近似解.解的精度很高，並逐級提高.如果用正則攝動法求解此類問題，則當自變量較大時，誤差很大 -
The existence and the convergence of the fully discrete format of nonlinear galerkin mixed element method with time second order accuracy for the non stationary conduction - convection problems are showen
給出了熱傳導-對流問題非線性galerkin全離散混合元解的存在性和收斂性。
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