時域微分 的英文怎麼說
中文拼音 [shíyùwéifēn]
時域微分
英文
time derivative-
Constructing quantitative model with ordinary differential equations for the cell - cycle control system, it is appropriate to use ordinary differential equations ( odes ), because molecular diffusion, transcription, translation and membrane transport seem to be fast ( a matter of seconds ) compared with the duration of the cell cycle ( hours ). spatial localization of reactions can be handled by compart - mental modelling, in the spirit of pharmacokinetics
對于這樣的細胞周期控制系統,應用常微分方程是適合的,因為比起細胞周期的時間(以小時計)來,分子擴散,轉錄,翻譯和膜運輸是很快的(以秒計應用藥物動力學的區域化模型的方法,可以處理反應的空間分佈。This paper mainly focuses on the noise limiting by means of the direct sequence spread spectrum ( dsss ) and the analysis of the transmission performance of the plc and some digital modulation technology. the contents of the paper is as follows : 1 ) the technical feasibility is proved after simulating noise limiting principle of dsss by means of systemview, the simulation software ; 2 ) a kind of band pass filter ( bpf ) is realized according to the requirement of filter and the principle of butterworth approximation, which satisfies the index of performance of dsss. 3 ) the low voltage plc system includes the sc1128, the specific modulation / demodulation ic, the bpf filter and other circuit components, furthermore, the control function of system is realized by means of the personal computer and the microcontroller
本課題在對低壓電力線的傳輸特性和數字調制技術進行分析的基礎上,將通信理論中的直接序列擴頻技術( dsss )用於解決低壓電力線通信的干擾問題,主要研究內容如下: ( 1 )用通信模擬軟體systemview對dsss技術的通信和抗干擾原理進行模擬分析,分別對時域和頻域下採用dsss技術前後接收信號的頻譜進行分析,驗證dsss技術在本系統中的可行性; ( 2 )由dsss技術對濾波系統的要求,根據濾波理論分析了巴特沃思型濾波器的逼近原理並設計了合適的濾波電路; ( 3 )用調制解調晶元sc1128和自行設計的濾波器加之輔助外圍電路,構造出低壓電力線載波通信系統,並採用atmel公司的單片機設計了接收和發射電路的微控制器; ( 4 )分別對採取抗干擾措施前後輸入和輸出信號進行對比實驗,並對結果進行分析,驗證了dsss技術對干擾信號的抑制作用。It can cancel the harmonic phenomena along cross directions and deduce the cost of computation. in chapter four using the impulse characteristics of inciding wave, we test the energy peaks in the transient impulse response of radar targets
本文第四章用能量峰概念和微分參數估計的方法,在時域研究了目標脈沖響應的特性,該方法可以分解出目標上不同散射中心的散射波。The topic of this paper originates from the national nature science fund " fdtd analysis and design of microwave active integrated circuits ". an analysis of microwave active circuits using fdtd method with the emphasis on the several methods with which to simulate the active devices in the microwave circuits is studied in details in this paper. and some practical electromagnetic problems are analyzed with these methods
本論文題目來源於自然科學基金「微波有源集成電路的fdtd模擬與設計」 ,研究了時域有限差分法對微波有源電路的分析,主要研究了微波電路中各種微波器件進行fdtd模擬時的幾種處理方法,並採用這幾種方法分析了幾個實際的電磁問題。In light of the limitation of fast fourier transform ( fft ) for the method of traditional spectrum analysis to analyze the unsteady signal, wavelet and wavelet analysis are made for the typical unsteady process signal of starting up and shut down with the good characteristic of simultaneous localization in both the time and the frequency domains based on the field test on the vibration of two - row placed units in lijiaxia hydropower station, in which the signal is decomposed into different frequency band, and then the weak signal is caught and the dominant frequency is picked up for the analysis of the vibration source
摘要基於李家峽水電站雙排機組振動的現場試驗研究,並且針對傳統頻譜分析方法傅立葉變換( fft )對于非平穩信號已力不從心這一缺陷,利用小波分析方法在時域和頻域上同時具有良好的局部化性質,通過對開停機這一典型非平穩過程信號進行小波及小波包分析,將其分解到不同頻帶內,獲取微弱信息和提取優勢頻率,並對其作振源分析,得出開停機初始時刻因水流不穩均出現強烈的振動現象,且低頻段信號能量最大,開停機過程水流脈動壓力和尾水渦帶擺動是引起定子基礎振動的主要原因。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。The various functions inside the virtual spectrum analyzer introduced in the paper is time domain wave analysis, fft transfer, ifft transfer, cross analysis, and so on, which are all described in function controls. finally, this paper introduce the assemble of intelligent controls - oriented virtual instrument. and use classical signals and industrial practices to demostrate the accurate of virtual spectrum analyzer
本文介紹的智能控制項化頻譜分析儀所具備的功能,有信號的時域分析、 fft變換以及ifft反變換、信號的微積分運算、信號的頻譜分析、信號自功率譜密度函數計算、信號互功率譜密度函數計算、頻率響應函數計算和相干函數計算,都是集成在功能控制項裏面的。In 6. 635, topics covered include : special relativity, electrodynamics of moving media, waves in dispersive media, microstrip integrated circuits, quantum optics, remote sensing, radiative transfer theory, scattering by rough surfaces, effective permittivities, random media, green ' s functions for planarly layered media, integral equations in electromagnetics, method of moments, time domain method of moments, em waves in periodic structures : photonic crystals and negative refraction
本課程所覆蓋的論題包括:狹義相對論、運動媒質的電動力學、色散媒質中的波、微帶集成電路、量子光學、遙感、輻射傳輸理論、粗糙表面上的散射、有效介電系數、隨機媒質、平面層狀媒質的格林函數、電磁學中的積分方程、矩量法、時域矩量法、周期結構中的電磁波:光子晶體和負折射率。In this paper, by using monte carlo method with irregular grid random walk in time - space domain the problem of mass concrete transient temperature field was solved
摘要利用求偏微分方程的蒙特卡羅演算法,通過在時空域中不規則網格隨機游動來求解大體積混凝土不穩定溫度場。Time history analysis is carries on after the seismic waves being numbered according to period, input values of seismic wave to vibration equation of system, adopt the method of progressive integral to gain the whole course of the structure ' s state at the whole earthquake
時程分析是將地震波按時段進行數值化后,輸入結構體系的振動微分方程,採用逐步積分法得出結構在整個地震時域中振動狀態的全過程。The above spatial and temporal discretization in the boundary, and two - directional average in the intersection, can satisfy completely n - s equations, and have high accuracy in the all computational regions
對邊界上的空間微分採用高階緊致差分格式離散,時間微分採用四階時間推進處理,在交界處採用雙向差分平均法,保證了整個計算域上的流動都滿足navier - stokes方程,並具有高階精度。Firstly, we investigate the dirichlet problem ' s comparison principle on a bounded subset for this fully nonlinear intergro - differential equation, at the same time we must assume the measure in the intergro - differential item is absolute continuous
首先研究這類完全非線性積分微分方程在有界區域上dirichlet問題的比較原理,此時須假設積分項所涉及的測度是絕對連續的。However, when the applied bias voltage is located within negative slope regions of u - i curve, the superlattice will undergo a very fast dynamic process, changing from one stable state to another stable state. the superlattice exhibits temporal current oscillations in the negative differential conductivity region at fixed d. c
當外加電壓使電流處于正微分電導區變動時,超晶格的高低電場疇之間的疇邊界不發生移動,只是相應的電場強度作些調整;當外加電壓使電流處于負阻區域時,超晶格將經歷一個穩態到另外一個穩態的動力學轉變。A coherent electromagnetic pulse in the range between the far - infrared and microwave region is used as a detection source. the amplitude of the wave is recorded by electro - optical or photoconductive sampling. after fast fourier transform, the amplitude and phase of the wave is given, then the complex refractive index standing for the absorption and dispersion of the material in thz region is extracted
Thz ( 10 ~ ( 12 ) hz )時域光譜技術是20世紀90年代發展起來的一種新型的光譜測量技術,它使用頻率介於遠紅外和微波之間的相干電磁輻射脈沖作為探測源,利用電光取樣或光電導取樣的方法直接記錄thz輻射電場的振幅時間波形,通過傅立葉變換得到測量信號振幅和相位的光譜分佈,進而獲得材料在thz波段的復介電常數,即色散及吸收等信息。Image edge detection based on multiresolution wavelet transform makes up these shortages before. wavelet theory has good local inspect ability in time region and frequency region, and the character multiresolution. these are theory basis that wavelet transform is applied to cell image edge detection
小波變換是80年代後期發展起來的一種變換域信號處理方法,具有時域和頻域上良好的局部檢測能力和多解析度分析的特點,從而被譽為「數學顯微鏡」 ,這是我們將小波變換應用於細胞圖像邊緣檢測的理論依據。As a new type of time - frequency analysis media, it excels in its good localization character both in time domain and in frequency domain comparing with traditional fourier analysis. it changes its sampling steps to smaller and smaller so as to analyze high frequency part, focusing on any part of the object been analyzed. to some extent, wavelet analysis is called " math microscope "
作為一種新型的時頻分析方法,它優于傳統fourier變換的優點是在時域和頻域同時具有良好的局部化性質,可對高頻成分採用逐步精細的時域采樣步長,聚焦到對象的任意細節,因此被譽為「數學顯微鏡」 。Wavelet has good localizing quality at time domain and frequency domain simultaneously and the characteristic of multi - resolution ratio analysis, so it can fulfill all kinds of wave - filtering needs such as low - pass, high - pass, sink wave, random noise denoising. compare with readitional wave - filtering methods, wavelet has incomparable advantage. wavelet has become an effective means of signal analysis and is intituled as math microscope of signal analysis
小波分析由於在時域頻域同時具有良好的局部化性質和多解析度分析的特點,因此不僅能滿足各種去噪要求如低通、高通、陷波、隨機噪音的去除等,而且與傳統的去噪方法相比較,有著無可比擬的優點,成為信號分析的一個強有力的工具,被譽為分析信號的數學顯微鏡。In this thesis, author briefly introduces basic theory of fdtd method at first, and research the method for analysing fss : the finite difference time domain combined with periodic boundary condition ( pbc ) and absorber boundary condition ( abc ) becomes the accurate and efficient tools for analysing frequency selective surfaces
其中時域有限差分法( fdtd )是求解麥克斯韋微分方程的直接時域方法。本文從fdtd的基本演算法原理出發,研究了頻率選擇表面的特性分析。其中包括了fdtd方法與周期性邊界條件、吸收邊界條件相結合,形成分析各種周期性結構準確、有效的通用工具。In the case of same local observation clutter power, based on the fusion rule proposed in [ 391, a novel method is proposed to solve the distributed system included any kind of lds by the property of laplace transform. this method overcomes the shortcoming of supposing the same local snr in other method. by computer simulation, some available conclusions are found based on these results
在假設局部觀測雜波功率水平相同的條件下,針對文獻[ 39 ]提出的融合方案,利用laplace變換的頻域微分性質,提出了一種針對局部採用任意數量的不同cfar檢測器時系統的檢測概率和虛警概率關于固定門限的求取方法,克服了以往需要假設局部信雜比相同的缺憾。In the case of same clutter power in lds, based on the fusion rule proposed in [ 171 ], a novel method is proposed to solve the distributed system included any kind of lds by the property of laplace transform. this method overcomes the shortcoming of supposing the same local snr in other method
在局部傳感器雜波功率水平相同情況下,針對文獻[ 171 ]中提出的融合方案,利用laplace變換的頻域微分性質,提出了一種針對局部採用不同cfar檢測器時系統的檢測概率和虛警概率關于固定門限的求取方法,並克服了以往需要假設局部信雜比相同的缺憾。分享友人