to a first approximation 中文意思是什麼

to a first approximation 解釋
大致上
  • to : adv 到某種狀態；〈特指〉到停止狀態；關閉。 ★也常和動詞結合，略去其後賓語，而構成成語： The door i...
  • a : an 用在以母音音素開始的詞前〉 indefinite art 1 〈普通可數名詞第一次提到時，冠以不定冠詞主要表示類...
  • first : adj 1 最初的，最早的。2 最上等的，第一流的。3 基本的，概要的。4 高音（調）的。n 1 最初，第一；第...
  • approximation : n. 1. 接近；近似。2. 【數學】近似值。3. 概算，略計。
  1. At first, this paper analyzes the factors of water - sand influencing water level of yellow river and the feasibility just using the factors of water - sand to study water level, and collects the corresponding data ; secondly, because there are strong nonlinear relation in the corresponding data, by meticulous theory analysis, this paper integrates basic nonlinear analysis method, theory of random analysis, method of least squares and so on. it puts forward a method which can get the high accuracy simulation of the data, perfects the multi - factor analysis of variable ( over three factors ) of the statistic ; thirdly, it applies the method to the approximation of corresponding water level process which belong to the capacity of sand of middle - high and middle - low, and get the high - accuracy simulation about the typical nonlinear relation ; at last, this paper definitudes the main influence mode that the capacity of sand. it mainly unite with other factors to work on the water level in the yellow river lower reaches ; mor eover, this paper analyzes the difficult point and the direction of improvement to realize the accuracy forecasting of the flood level of erodible - bed channel

    首先，系統分析了影響黃河水位的水沙因素，及僅用水沙因素有效研究水位的可行性，並按變量對應思想採集它們的相應數據；其次，由於相應水位過程數據中含極強的非線性關系，本論文經細致的理論分析，將基本的非線性分析方法、統計建模方法、隨機分析理論、最小均方誤差原則等等數學理論及方法有機揉合，提出了能有效實現這類數據高精度擬合的分層篩選法，並改進了統計學中多因子（三個以上）方差分析法；再次，將這一方法用於黃河中高及中低含沙類洪水相應水位過程的擬合，實現了這一典型非線性關系的高精度擬合，各年汛期上下游相應洪水位過程的擬合誤差都較小；最後，明確黃河下游含沙量對水位的主要影響方式，即含沙量主要是與其它因素聯合對水位作用；另外分析了要實現變動河床洪水位過程準確預報的困難所在及改進方向。
  2. The dissertation proposes originally the idea of decomposing the time - variant load to solve this problem. first, the time - variant load is decomposed into the time - variant load characteristic and the time - variant load model due to the modeling method. second, the multi - curve approximation method is proposed to identify the load parameters, which to a great extent, reduces the effects on the time - variation of the load model from modeling method

    針對負荷的時變性，論文首次提出了將負荷時變性分解的思想，首先將負荷的時變性分解為負荷特性的時變性和由建模方法引起的負荷模型的時變性，然後提出了多曲線擬合參數辨識方法，很大程度上消除了建模方法引起的負荷模型的時變性。
  3. Secondly, the effectiveness and limitation of the classical perturbation, such as the method of multiple scales and the poincare - lindstedt method, are discussed in detail through a duffing oscillator with delayed velocity feedback. it is shown that the two perturbation methods are effective only in solving the approximate solution of the first two orders. an ambiguity or paradox will be encountered when they are used to seeking for the third or higher order approximation of solution

    其次，以一具有時滯速度反饋的duffing系統為例，研究了經典攝動法如多尺度法， poincar - lindstedt法等在求解時滯微分方程級數解時的適用性和局限性問題，指出利用這些方法只能有效求得系統的前兩階近似解，而在求系統的三次以上近似解時會出現矛盾或二義性。
  4. Firstly, based on backstepping and the supervisory control strategy, a robust adaptive fuzzy controller is designed for a class of nonlinear systems. the first type fuzzy logic system is used to approximate the unknown part of the process. the adaptive compensation term of the optimal approximation error is adopted

    本文首先針對一類不確定非線性系統，基於backstepping方法，利用監督控制，引入最優逼近誤差的自適應補償項，並利用型模糊邏輯系統逼近系統的未知部分，提出了一種魯棒自適應模糊控制器設計方案，運用李亞普諾夫第二方法，先證明了閉環模糊控制系統全狀態有界，再證明了跟蹤誤差收斂到零。
  5. The results of numerical experiments, using the four - dimensional variational data assimilation system of the nonhydrostatic mesoscale model mm5, show that : the tangent linear model and adjoint model conducted by keeping the " on - off " switches the same as the basic state, can provide a good approximation of the first - order information to the nlm perturbation and a good descent direction for the minimization procedure ; switching on and off at every other time step in the kuo cumulus parameterization scheme do n ' t impact the convergence rate of cost function ; the existence of the switches do n ' t impact improvement to the mm5 model rainfall prediction because that not only specific humidity, but also wind, temperature and pressure are assimilated into the model

    非靜力中尺度數值模式mm5的四維變分資料同化系統進行的數值試驗結果表明： 「開關」變量保持與基態一致，所構造的切向線性模式能夠提供關于非線性模式擾動的一階近似，伴隨模式所計算的梯度值能夠為最小化過程提供較好的下降方向；郭氏降水參數化方案中對流每隔一個積分步的交替發生並不影響目標函數最小化的收斂速度； 「開關」變量的存在也不影響將風、溫度、氣壓和比濕結合起來同化對mm5降水預報準確性的提高。
  6. So as to deal with this problem, local b - spline surface designing method with complicated trimmed boundary constraints is advanced. for two neighboring surfaces, we first trim a belt along the common boundary and then bridge a b - spline surface between these two trimmed surfaces with a smooth blending. with respect to the comer area comprised of several adjoining surfaces, a rectangular region covering the comer area is obtained by trimming operations at first, and later a local b - spline for filling the rectangular region is completed through interpolation or approximation

    在兩張相鄰的曲面之間，先在其公共邊界處裁剪出一個帶狀區域，然後再採用曲面搭接的方式實現曲面之間的光滑過渡；而在鄰接曲面的公共角點處，先在該角點附近區域裁剪出一個矩形拓撲域，然後運用插值或逼近的方法，設計出一張既滿足於該區域的邊界條件同時又插值或逼近內部采樣點的b樣條曲面。
  7. This approach is mathematically a first approximation to messages with a variable size bear with me, i will keep it short and simple

    這個方法在算術上最接近大小不定的消息（請原諒，我將盡量使它簡短） 。
  8. In chapter 3 we construct two approximation algorithms which applying bin packing algorithms for scheduling problems, one is ff ( first fit ) algorithm used in parallel machine scheduling problem pm / / dj = d / n which has a lower bound of asymptotic worst - case performance ratio, another problem is scheduling independent parallel tasks in parallel identical machine systems to minimize the makespan, we use strip packing method for it and give an approximation algorithm with asymptotic performance ratio no more than 1. 6

    第一個演算法利用裝箱問題中的ff （ firstfit ）演算法求解極大化按期完工工件數的平行機排序問題pm d _ j = d n - u _ j ，該近似演算法具有漸近性能比下界。第二個近似演算法利用二維裝箱中strippacking問題的演算法求解以極小化makespan為目標的帶并行工件的平行機排序問題，該演算法的漸近性能比具有下界1 . 5和上界1 . 6 。
  9. Simulations results demonstrate the optimized model has a higher approximation to the objective system than does the previous one. next, fuzzy controller for the supply system is designed as follows : first, the structural decoupling is performed to formally decompose the 2 - input 3 - output controller as three 2 - input single - output ones, which greatly simplifies the design of the fuzzy controller. second, rudimentary control rules are identified and then improved by trial - and - error adjustment

    進而，本論文又研究設計了供水系統的模糊控制器：首先採用結構解耦的方法，把兩輸入三輸出模糊控制器形式化地分解為三個兩輸入單輸入的模糊控制器，這樣就大大簡化了模糊控制器的設計，接著採用模糊辨識方法得到初步的模糊控制規則，並通過進一步的調試使控制規則得以完善。
  10. Before the beginning of the seventies, in a first approximation, the carbon cycle due to energy production was " closed ", in an equilibrium situation until human activities did start to tilt the balance

    在上個世紀七十年代開始之前，由於能源生產的碳循環在人類的活動使其失去平衡前首次接近平衡狀態。
  11. Based on the analysis of the methods for optimizing the fuzzy neural networks before, this paper has finished following works : 1 ) we proposed a learning algorithm based on tabu search for fuzzy neural networks based on the model of anfis proposed by jyh - shing roger jang. then used the system for one variable function ' s approximation. 2 ) based on the first research, we improved the tabu search algorithm for the purpose of approximating complex functions. 3 ) analysis the capabilities of tabu search, and discuss the approximation ability and generalization ability of the fuzzy neural networks system according to the compute results

    本文在對以前的模糊神經網路參數學習演算法進行分析的基礎上，做了以下幾個方面的工作： 1 ）根據禁忌搜索演算法的特點，在jyh - shingrogerjang提出的anfis模型的基礎上，將禁忌搜索演算法應用於模糊神經網路線性和非線性參數的學習上，並將該模型用於單變量函數的逼近； 2 ）在第一階段的基礎上，對演算法進行了改進，使改進后的演算法能夠適用於復雜的ii函數逼近問題; 3 ）根據計算機模擬的結果，對禁忌搜索演算法的性能進行了分析，並對該模糊神經系統的函數逼近能力和泛化能力進行了討論。
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