頻率密度 的英文怎麼說
中文拼音 [bīnlǜmìdù]
頻率密度
英文
frequency density-
The experimental results show : the flattop phenomenon on the diode voltage pulse was very apparent for using the carbon fiber cathode, that is to say, the pulse duration of the diode voltage was widened ; moreover, under the condition of the same power of microwave, the pulse duration of the out - put microwave was prolonged by about 30 % ; the peak power of the microwave was enhanced by 3db
通過在裝置上做的兩種陰極的對比實驗,結果顯示:碳纖維陰極的使用,改善了電子束質量,使輻射微波的脈寬增加了30 %以上,輻射主瓣方向上的功率密度提高了3db以上,頻譜分佈較純凈,實現了微波的高效輸出。With the development of power electronics technology and devices in recent years, instead of using the industrial frequency transformer to boost voltage, dc / dc high frequency converter achieves the function. the system has higher power density and conversion efficiency, and the size, weight, ac noise of which has been greatly reduced
近年來,隨著電力電子技術與器件的迅速發展,使用dc dc高頻變換技術代替工頻升壓,系統具有較高的功率密度與轉換效率,裝置體積、重量與交流噪聲大大減小。The signal process function of the software include these function : digital filter, windowing, auto - correlation function and cross - correlation function, mean and variance, probability density function and probability distribution function statistic ; auto - power spectrum, cross - power spectrum, frequency response function, coherence function, cepstrum analysis based on fft ( fast fourier transfer ) ; joint time - frequency analysis based on stft ( short - time fourier transfer )
軟體的處理功能包括:數字濾波、時域加窗、自相關與互相關處理、均值和方差計算、概率密度和概率分佈函數計算;在快速傅立葉變換( fft )基礎上計算自功率譜、互功率譜、頻率響應函數、相干函數、倒頻譜分析;基於短時傅立葉變換( stft )的聯合時頻分析等。Experimental study on that 532nm 、 1064nm 、 1319nm 5khz frequency pw laser irradiate the ccd respectively. with the data of experiment, the thresholds of laser power density that induce ccd saturation, crosstalk and irreparability damage were calculated. the phenomenon that 532nm 5khz laser can induce part of ccd functional damage but absolutely damage was found
根據實驗數據計算了532nm 、 1064nm高重頻脈沖激光使ccd出現飽和、串擾以及被破壞的功率密度閾值;實驗發現一定功率密度的高重頻532nm脈沖激光可以使ccd局部損傷而不致整體破壞;實驗進一步證實了1319nm激光不能使可見光ccd產生響應。Some researches about frequency doubling are made, and two methods to improve intensity of second frequency generation are given. we realized q - switched 532 nm laser, by using nd : gdvo4 as laser crystal, using cr4 + : yag as saturable absorber, using ktp as intra - cavity frequency doubling crystal. average power of 109mw, repetition of 40khz, pulse width of 30ns, pulse energy of 2. 6uj, peak power of 91w are obtained
4 .對倍頻理論進行研究和分析:討論兩種提高二次諧波功率密度的方一法;實驗匕在國內首次實現ld端面泵浦nd : gdvo4 / ktp ,用cr4 + : yag作為可飽和吸收片的綠光激光器,腔內倍頻得到了平均功率為109mw 、重復頻率為40khz 、脈寬為3ons 、單脈沖能量為2 . 6閃、峰值功率為glw的調q綠光輸出。Moreover, a method for iterating thermal and magnetic analysis is put forward. in chapter 5, the distributed characteristics of eddy and temperature fields in induction heating process are simulation by fem respectively, including the distributions of eddy and temperature fields during the whole induction heating process, the influence of frequency and magnetic disperse, and the prediction of hardened depth
第五章:用ansys軟體對感應加熱過程中工件內渦流場、溫度場的一些基本問題進行模擬及分析,主要包括:加熱過程中工件渦流功率密度及溫度分佈規律;頻率與磁力線逸散對加熱效果的影響;同時對感應淬火淬硬層深度進行了模擬預測。Magnetics is one of the main factors, which limit the power - density and characteristics of power module. for lowing weight and volume, reducing power loss and ripple current, improving dynamic performance, the magnetic - integration technique has been one of the research populations in power electronics. the thesis researches the magnetic - integration applied to the active - clamp forward converter so as to reduce the ripple current and improve its performance
對于已經大量採用高頻軟開關技術的模塊電源,限制其功率密度進一步提高、性能進一步改善的重要因素之一是磁性元件,而磁集成技術由於具有可以減小磁件體積重量,減少磁件損耗,減小輸出電流脈動,改善輸出動態性能等優點,成為目前電力電子技術的研究熱點之一。Frequency code is not uniformity distribution and keeps to a probability distribution function defined by the spectral characteristics of the target of interest. the phase code is equally duality pseudo - random sequence and used to reduced the sidelobes of the signal correlation function. and the mismatch - phase sequence is corresponding with the frequency sequence one by one
而頻率編碼為不均勻分佈,由所觀測目標的頻譜信息提取出概率密度函數決定頻率編碼序列的分佈;相位編碼為二元的偽隨機序列,採取均勻的二相編碼,消減同頻脈沖帶來的過高的相關函數的旁瓣;而失配相位為與頻率編碼相一一對應于各子脈沖中。The frequency band extension with time base jitter is also studied by simulation. the results show that the compensation of time jitter can reduce the error of signal and then increase the accuracy of frequency band extension
對時基抖動的頻帶展寬技術的模擬結果表明,通過擴展的概率密度法對時基抖動的補償,可以減小信號的誤差,因而提高頻帶展寬的精度。With the development of radar technology, radar system has been more diversiform and complicated, which make ecm face much more complex electromagnetic environment. how to sort and analyze signal exactly is an important research of ecm. in this paper, we mainly research the signal sorting 、 system simulating and dsp realizing : 1. the paper introduces the environment of ecm and analyses the character of time domain 、 frequency domain 、 air space 、 power density and polarization detailedly
本文主要就是研究復雜電磁環境下的彈上電子對抗系統信號分選關鍵演算法、系統軟體模擬以及dsp的實現,主要包括以下幾個方面: 1 .對電子對抗環境進行了介紹,並對雷達偵察機的信號環境的時域特徵、頻域特徵、空域特徵、功率密度(能量)特徵以及極化特徵進行了詳細的分析,得出了對雷達偵察接收機信號分選系統設計的主要依據。From above analysis, the thesis gets conclusions as following : ( 1 ) the frequencies of multi - tower building are so dense and the coupling in each mode is so evident that the cqc method instead of srss should be used to calculate the seismic action effect ; ( 2 ) torsion effects is distinct between the modes of asymmetry multi - tower structure and it is necessary to take translation - torsion coupling into account ; ( 3 ) the effect of the enlarged base rigid on the seismic properties is very big, the rigid ratio of the enlarged base to towers in asymmetry multi - tower structure should be designed in a proper range ; ( 4 ) the distribution of plane rigid is asymmetry because of the asymmetry layout of towers. the torsion effects of structure not only result in large torsion internal force in vertical element resisting lateral displacement, but also make large influences on the stress of transfer plate and near floors, thus it is necessary to strengthen those floors
通過上述分析,得出以下主要結論:多塔樓結構存在頻率密集現象,各振型間耦聯效應明顯,地震作用計算應採用cqc組合原則而不能簡單地採用srss組合原則;非對稱多塔結構的振型中,扭轉作用明顯,平扭耦聯效應值得考慮;裙樓剛度對整體結構的抗震性能影響很大,非對稱多塔結構宜控制裙樓與塔樓剛度比在適宜的范圍;非對稱多塔易導致平面剛度分佈不均勻,結構扭轉效應不僅在豎向抗側構件中引起較大的扭轉內力,對轉換層樓板應力有較大的影響,且延續至相鄰樓層,對相應樓層均應採取相應的加強措施。The prototype test results indicate : voltage mode and current mode ac - ac mode ac / ac converters with high frequency link have the advantages such as high frequency electrical isolation. simple topology, two - stage power conversions, high power density, bidirectional power flow, good line current waveform, no audio noise, high converting efficiency, and high input power factor etc. this kind of converter lay the key technical foundation on new type regulated sinusoidal ac power supply, electronic transformer, ac regulator, and wave converter etc
試驗表明,這類變換器具有高頻電氣隔離、電路拓撲簡潔、兩級功率變換( lfac hfac lfac ) 、功率密度高、雙向功率流、無音頻噪音、變換效率高、網側功率因數高等優點。為新一代正弦交流穩壓器、電子變壓器、交流調壓器、同頻波形變換器的實現奠定了關鍵技術基礎。Based on comparison between the parallel - parallel and parallel - serial combination ttfc, a novel two - transistor forward converter with parallel - serial / serial combination is proposed. this converter reduces greatly the current overshoot of the primary side switches and the voltage overshoot of the rectifying diodes. moreover, the size and weight of the converter can also be reduced by interleaving technique and increasing frequency
本文在對並-串型和並-並型雙管正激組合變換器進行了詳細比較研究的基礎上,提出了一種新型並-串串型雙管正激組合變換器,該組合變換器可以大大減小原邊開關管的電流應力和副邊整流電路中二極體的電壓應力;通過交錯控制及提高開關頻率,大大提高了變換器的功率密度。The volume of the output filter can be reduced greatly used in cascade inverter with carrier - phase - shifted spwm technology which has a high equivalent switching frequency and a good output sine wave. it is the base of the high power density of asi
載波移相正弦脈寬調制技術有獨特的消諧波優勢,其等效開關頻率高,輸出波形正弦度好,可以大幅減小濾波器體積,為實現系統的高功率密度奠定基礎。Because p - si is of more special characteristics, comparing to a - si and c - si, firstly, i set forth electrical features of p - si film and acknowledge profoundly electrical mechanism of p - si film. then three parameters of laser annealing, including laser frequency -, accepted - pulse - times and laser power density are studied how to influence crystallization of p - si
因為多晶硅和非晶硅及晶體硅相比具有更獨特的特點,所以我們先闡述了多晶硅薄膜的電學特點,對多晶硅的導電機理有了深刻的了解;然後研究了激光頻率、受光次數和激光功率密度三個參數對晶化多晶硅的影響。In these equipments, the motor driver should provide high performance, small size, and low cost. it is a good solution to integrate the motor driver system. the techniques of integrate the motor driver system is the combination of power electronic techniques with micro - electronics techniques ( integrate the motor driver system by power integrated circuit techniques or by packaging techniques )
小型電動機變頻調速集成化是將微電子技術、集成電路技術、電子系統裝聯技術與電力電子技術相結合,使現在市場上的小型電動機變頻調速系統器件化、模塊化、高功率密度化、小型化,同時降低調速系統的成本,減小或排除長期以來阻礙了小功率電動機變頻調速系統廣泛應用的經濟方面的因素。The lifetime of particles co - doped with li + and na + increased as compared to that of un - doped one. however, the lifetime decreased as co - doped with other dopants. in addition, we also studied that ultraviolet ( uv ) light - induced spectral change in eu3 + - doped aluminosilicate glass and red to blue up - conversion emission of tm3 + -, yb3 + - doped y2o3 nanocrystals
( 2 )在紫外光輻照下, eu ~ ( 3 + )摻雜的氧化物玻璃電荷遷移帶強度降低,通過研究輻照與激光的功率密度、波長的關系,發現這種變化屬于單光子過程,並具有頻率選擇性。Then, base on the determine channel modeling methods, we present a frequency - selective mimo fading channel with von mises probability density function, which is used to characterize non - uniform angle - of - arrival caused by non - isotropic scattering. then we analyze partial cross correlation function of proposed model and proved the model theoretically
然後,通過對其它多入多出通道模型的分析和對比,並基於確定性通道建模方法,建立了一種通用的頻率選擇性多入多出衰落通道模型,藉助「 vonmises 」概率密度函數,以描述非均勻散射體導致的非均勻本地來波方向分佈。Soft - switching pwm converters integrates the advantages of pwm converters and resonant converters, they not only achieve soft - switching for the power switches, but realize constant frequency control, leading to high efficiency, high power density and high reliability
Pwm與諧振技術結合起來,既可實現變換器的恆頻控制,又可實現變換器的軟開關,從而可以大大提高變換器的效率,減小變換器的體積,實現變換器的高功率密度。This kind of converter has the advantages such as high frequency electrical isolation, simple topology, two - stage power conversion ( lfac / hfac / lfac ), high power den sity, bi - directional power flow, soft commutation of output cycloconverter, uni - polarity spwm waveform, no audio noise etc. the correction and advance of the new concept of the 220v + 10 % ( 50hz ) / 220v ( 50hz ) uni - polarity phase - shifted controlled voltage mode ac / ac converter with high frequency
這類變換器具有高頻電氣隔離、電路拓撲簡潔、兩級功率變換( lfac hfac lfac ) 、功率密度高、雙向功率流、輸出周波變換器實現了zvs換流、單極性spwm波、無音頻噪音等優點。分享友人