頻段變換 的英文怎麼說
中文拼音 [bīnduànbiànhuàn]
頻段變換
英文
frequency band shifting-
The specific research methods are listed : 1. matched filter taking the max ouput snr as the best rule correlates nonstop divided signal and divided echo to detect low snr target signal. then all one dimension divided correlation outs and done fft in portrait to leach interferential signal such as static or low rate mussy meaves, many pathway echo and so on and to take target ' s time difference and doppler frequency that combine parameters that target ' s direction taken from antenna and so on to implement target ' s orientation and tracking
具體研究方法如下： 1 、採用以輸出信噪比最大為準則的最佳匹配濾波器來對分段的參考和目標信號作相關處理來檢測低信噪比目標信號，然後對一維分段相關輸出組作縱向傅立葉變換來濾除靜態或低速的雜波、多徑回波等干擾信號，並提取目標的時差和多普勒頻率，再結合由天線獲得的目標方向等參數，就可以實現目標的定位和跟蹤。Because of the presence of the first - order sea echoes with dominant amplitude, the doppler resolution technique which based on the range - velocity transformation is needed to extract the targets information in hf radar
高頻雷達工作在擁擠的短波波段，由於絕對占優的一階海浪回波的存在，必須採用基於距離?速度譜變換的多普勒頻率分辨技術來處理雜波，以提取目標信息。We use fast fourier transform arithmetic to calculate two seriate images. this article discusses the basic principle of the cross - correlation arithmetic in detail, discuss each stage of its produce and development and also discuss the thinking, the merit and the defect of each algorithm. based on these discusses, we confirm our algorithm and realize it in programming with c + +
粒子圖像的匹配演算法的主要運算是將兩連續的視頻圖像進行基於快速傅里葉變換的互相關運算，本文詳細論述了相關演算法的基本原理，它的產生和發展的各個階段，在比較了各種演算法的基礎上確立了自己的演算法並以c + +編程實現。At present, people usually use birefrigence and quasi - phase - matching methods to achieve higher effiency in the process of conversion. a significant advantage of quasi - phase - matching method is that the interaction is occurred through the largest element of the x ( 2 ) tensor ; the period of optical superlattice can be designed randomly, and any interaction can be matched without walk - off angle ; they are fitted to be used in frequency conversion of lower power especially. the quasi - phase - matching method has some advantages over birefrigence method, improving the efficiency of frequency conversion ; the range of frequency conversion covers its whole transperant wavelength
由於準相位匹配技術有其獨特的優勢，可以利用非線性光學晶體的最大二階極化張量，如ppln 、 pplt 、 ppktp用的非線性極化張量都是d _ （ 33 ） ，其有效非線性系數高出普通非線性光學介質（如bbo 、 lbo 、 ktp ）一個數量級，而且可以人為靈活設計調制周期，通過周期設計其頻率變換范圍可以覆蓋準相位匹配介質的整個透明波段，選擇無走離效應，解決了常規pm難以解決的問題，拓寬了非線性晶體的應用范圍，極大地提高了頻率轉換效率，已成為非線性光學材料和固體激光器的研究熱點之一。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。Another aspect of this paper is to expand the working band of hartmann - shack wavefront sensor through frequency transfer of nonlinear optics
另一方面，我們又對利用非線性光學頻率變換方法拓寬探測器件的響應波段，做了探索性的工作。We all know that the output of ultraviolet ( uv ) laser mostly depends on the conversion of nonlinear frequency, thus a new kind of excellent nonlinear optics ( nlo ) crystal is very important for the output of new wavelength
紫外波段激光的輸出主要採用頻率變換技術來實現，因此一種好的非線性光學晶體對于產生新的波長是非常重要的。This thesis presents a new audio digital watermark algorithm based on has model. the steps : first, it classifies the signals through fft ; second, calculating the tones, noise and the overall masking threshold of different phases through has, and changing the energy value of tones which are more than that of the overall masking threshold to embed the watermark information
提出了一種基於人類聽覺系統（ has ）模型的音頻數字水印演算法，該演算法首先對信號進行分段離散快速傅立葉變換（ fft ） ，再根據人類聽覺系統模型計算出各段的類純音、類噪音以及各段的總體掩蔽閾值，通過改變大於總體遮蔽閾值的類純音的能量值來嵌入水印信息。A x - band six - cavity tro is studied. with the voltage 760kv 6ka and the magnetic field 2. 6t in the simulation, output power is about 1. 5gw is obtained, and interaction efficiency is 31 %. a noveland high accurate numerical synthetic technique is presented for determining the high frequency characteristics of six - cavity with open boundary
對粒子模擬的輸出微波功率的作出診斷，找到讀取微波功率快速有效的方法：在電場和磁場同相的前提條件下，對時域波形進行傅立葉變換，微波功率頻域的二倍頻所對應的幅度即為微波x波段渡越輻射振蕩器的理論和實驗研究平均功率的大小。It is shown by structural seismic response of four wavelets that littlewood - paley wavelet is not suitable for structural seismic response, because structural response is too small, meyer wavelet is a better wavelet for structural seismic response, for it ' s structural response is agreement with the finite element method, and also harmonic wavelet, structural response under earthquake is a little bigger than finite element method, structural response under odd exponent wavelet is also bigger than finite element method, this method is very simple by wavelet transform, wavelet transform method is different from old methods, one is with which not only knows the effects of earthquake wave detail frequency - band on structural response, but also considers earthquake wave ' s non - stationary of frequency and time - domain value, another is the second mode shape and higher mode shape response that do n ' t attenuate so fast
通過對這四種小波的結構地震反應分析研究說明： littlewood ? paley小波不適合於用來作結構地震反應分析，因為在littlewood ? paley小波下的結構地震反應太小，不符合實際情況；用meyer小波作結構地震反應分析比較合適，和有限元法的結果比較接近；也可以用諧波小波來作結構地震反應分析，只是在諧波小波下的結果略為偏大；單邊指數小波下的結構地震反應分析比有限元法稍大一點，它通過小波變換大大簡化了結構地震反應分析。用小波變換方法來進行結構地震反應分析和以往方法不同的是：它不僅可以知道地震波的具體頻率段對結構反應的影響，而且同時考慮了地震波的幅值非平穩性以及頻率非平穩性；另外與以前方法得到的結果有差異的是，第二振型及以後的高一點的振型的反應沒有以前的方法衰減得快。In addition, the author puts forward that the eggs could be recognized based on the difference in the frequencies of their prompted sounds. because the eggs " prompted sounds are lied on low frequency bands, the microphone and sound amplifier that have excellent duration response should be used. the output signal from the sound amplifier is transferred to data signal by a / d card before it is put into computer
蛋品激勵出的聲音主要集中在低頻段，因此選擇在低頻段有好的頻率響應特性的麥克風和放大電路；放大輸出信號通過a / d採集板變換成相應的電壓數值信號送入計算機，對離散的信號數據進行傅立葉變換得到它的頻譜圖和各頻段能量分布圖；而後將能量分佈特徵數據作為神經網路的輸入值，這樣，好蛋和破損蛋的模型就建立起來。Doing the further research on the division frequency stack on the foundation of study of predecessor, at first the residual moveout correction is done to the seismic record, make the phase axle regularity, doing foundation for the same phase stack ; then carried on division scale processing by wavelet transform ; spectrum whitening is done to each scale, the high and low frequency band need to do prolongs, the middle frequency bands only increase the value of the frequency spectrum ; several kinds of methods that estimate the value of signal - noise ratio has been studied further, and summarize their advantage and disadvantage as well as the scope of application ; the seismic record after spectrum whitening is stacked by weighting with the value of the signal - noise ratio ; then estimate the value of signal - noise ratio which is each scale section after stacking, the scale that the signal - noise ratio is big is assigned big weighting, otherwise, the scale that signal - noise ratio value is small is assigned small weight ing, and carried on weighted reconstruct to each scale section
本文在前人研究的基礎上，在分頻疊加方面做了進一步的研究。首先對地震記錄進行剩餘時差校正，校齊同相軸，為同相疊加做好基礎工作；然後對地震記錄用小波變換的方法進行分尺度處理；對各個尺度分別做譜白化，對于高、低頻段需要做頻帶延拓，中間頻段僅提升頻譜值；對于幾種信噪比定量估計的方法進行了深入的研究，並且總結了它們的優缺點以及適用范圍；對譜白化后的地震記錄用信噪比估計值作為加權系數進行加權疊加；對于各尺度的疊加剖面也進行信噪比估計，對于信噪比大的尺度給予大的加權系數，反之，信噪比值小的尺度給予小的加權系數，對各尺度疊加剖面進行加權重構。Plasma characteristics of a rf ion source are investigated by emission spectroscopy. the spatiotemporal spectral line intensities of the first three atomic lines in hydrogen bahner series ( = 656. 28, 486. 13, 434. 05nm ) of rf ion source plasma, are measured with calibrated optical multichannel analyzer ( oma ). some plasma parameters, including electron temperature, hydrogen atom density and hydrogen ion density, are calculated and analyzed using partial local thermodynamic equilibrium ( plte ) theory and abel transform
實驗採用絕對定標后的光學多道分析系統（ oma ）測定了離子源等離子體不同時間和空間位置的氫原子巴耳末譜線系中前三條譜線（ = 656 . 28 ， 486 . 13 ， 434 . 05nm ）的強度，並採用plte的理論和abel變換方法，計算出了高頻離子源等離子體的電子溫度、氫原子濃度、氫離子濃度等參數在放電的不同階段和徑向分佈情況，並進行了簡要分析。It shows that when walk - off and diffraction effects could be ignored approximately estimation of the phase distribution of second - harmonic wave could be done. the far field divergent angle and second moment radius of harmonic wave will vary with the aberration of fundamental wave, but the far field divergent angle will be obviously smaller than that of fundamental wave. the phase distribution of both fundamental and harmonic wave is measured using hartmann - shack wave front sensor in the experiment with 1064nm and 790nm lasers, respectively
這說明利用非線性光學頻率變換方法拓寬波前傳感器件的響應波段是很難實現的，但是，通常三波相互作用過程的研究均是建立在平面波和理想高斯光束之上，因此我們對于位相畸變倍頻過程的研究是非線性光學領域一個重要而有意義的新課題，它有助於人們更加深入理解非線性光學效應，為進一步合理利用之奠定了理論和實驗的基礎。Fourier transform cannot offer entire information of signals, namely frequency information presenting to any period of time cannot be confirmed on earth. although, short time fourier transform can obtain local information, it is difficult to find a " good " time window to fit for every period of time
傅立葉變換不能提供信號完全的信息，即不知道頻率信息究竟出現在那些時間段上；短時傅立葉變換雖然可以獲得局部信息，但是對於一個時變的非穩定信號我們很難找到一個「好的」時間窗口來適應各個時間段。The chaos sequence was applied in these two algorithms to increase its security and was served separately as the random watermark generator and the watermark image encryption techniques. due to the analysis of the image characteristics, we determined the watermark strength by the classification of the image content and obtained better robustness and imperceptibility. new algorithms of meaningful digital watermarking in svd domain with chaotic transform encryption are proposed
混沌序列在這兩類演算法中分別作為隨機水印信號發生器和二值圖像水印的混沌加密手段，具有安全性高、形式簡單的優點；利用hvs特性，分別在時空域和dct頻率變換域中計算圖像內容的自適應嵌入強度，增強了演算法的穩健性；水印的嵌入和檢測計算復雜度小，演算法簡單。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。The type of the base function of wavelet analysis is not single, while the ft has only the sine ( or cosine ) function or exponential function. wavelet transformation has the character of multi - resolution analysis. wavelet transformation can analyze the signal in any precision ( resolution ) at any part of time and frequency according to the different translation factors and dilatation factors
小波變換具有多解析度分析的性質，對應于不同的伸縮因子和位移因子，小波變換能對信號的任何時間（空間）段、任何頻率段進行任何精度（解析度）的分析，在非平穩信號（包括瞬間信號）的分析中具有很大的優越性，分析時，在信號的低頻部分具有較高的頻率解析度和較低的時間解析度，在高頻部分則具有較高的時間解析度和較低的頻率解析度，被譽為「數學顯微鏡」 。In general, a watermark system must satisfy the two basic requirements : imperceptibility and robustness. in this thesis, we proposed a frequency - based watermarking algorithm using toral automorphisms, in which a kind of toral automorphism is employed to mix a recognizable binary image ( bw ), which contains the copyright information, into a noise - like signal
演算法簡單描述如下：首先用一個環形自同構映射把要嵌入的數字水印映射成偽隨機噪聲，然後把該偽隨機噪聲嵌入到宿主數據頻域的低頻段中，接著把得到的頻域系數進行相應的逆變換得到嵌入水印的圖象，最後對該嵌入水印的圖象進行視覺掩蔽處理。In vibration test, the signal is always along with noise. if the noise belongs to white noise, fourier transform is very suit to identify and process it, after then remove it. but when there exists low energy impact signal, traditional band pass filter remove noise and the precise position of impact signal is blured
對于白噪聲，由於它是穩定信號，所以也可以使用fourier變換定位，以便在合適的頻段進行提取。但是對于低能量突變瞬態信號，在信噪比比較低的情況下，由於帶通濾波的平滑作用，瞬態信號的位置信息也變得很模糊了。分享友人