frequency drift 中文意思是什麼
frequency drift
解釋
頻率偏移-
The limited sensitivity of present pulsar surveys and the greater frequency drift make the more distant pulsars difficult to observe.
目前脈沖星普查的有限探測靈敏度和大的頻率漂移，使我們難以觀測到更遙遠的脈沖星。 -
Automatic frequency drift rejector
自動頻率漂移抑制器 -
The detecting accuracy of the beam drift would be improved, as a high performance acoustooptic modulator modulates the frequency of the laser beam drift signal far away from the power frequency, the double power frequency and high frequency noises
具體包括: 1 .利用聲光調制器將光束漂移量信號調制到遠離工頻及其倍頻干擾和高頻噪聲的頻帶段，以期提高光束漂移量的檢測精度。 -
Thirdly, in the environment of labview, several kinds of vis used for sensor signal test are designed, including wave generation, time domain measurement, filter disposal, frequency analysis, etc. after that, wavelet analysis in the application of one - dimensional signal de - noise is studied, threshold and translation invariance wavelet de - noise are realized, and wavelet de - noise vi for zero drift signal of the fiber optic gyro in fcs is designed using labview
接著，在labview環境下開發了多種用於傳感器信號測試的虛擬儀器，具有波形發生、時域測量、濾波處理、頻譜分析等多種功能。隨后，研究了小波分析在一維信號消噪中的應用，實現了labview環境下的閾值法和平移不變量法小波消噪，並利用labview設計了飛控系統中光纖陀螺零漂信號的小波消噪儀。 -
Algan / gan hemt has high breakdown electric field, fast electron drift velocity and large electron concentration, so it has been used more and more in high frequency and large power fields
Algan / ganhemt由於具有擊穿電壓高、電子漂移速度快和電子濃度大等特點，已被越來越多地應用於高頻及大功率領域。 -
Silicon carbide is becoming the most promising semiconductor material for high temperature, high frequency and high power devices because of its superior properties such as wide band gap, high breakdown field, high electronics saturation drift velocity, and high thermal conductivity
Sic材料由於具有寬禁帶、高臨界擊穿電場、高飽和電子漂移速度、較大的熱導率等優良特性，因此成為製作高溫、高頻、大功率器件的理想半導體材料。 -
From some characteristics observed, such as the short lift time, narrow frequency band, fast frequency drift, quasi - periodic pulsation, spike event and complex magnetic structure, it is considered that the radiation mechanism of these events may be principally due to the electromagnetic waves magnified directly by the instable electronic cyclotron
從它們的觀測特徵：短壽命，窄頻帶，頻率快速漂移，及尖峰事件與磁結構復雜的大黑子活動區密切相關等，認為這些事件的輻射機制可能是電子迴旋脈澤不穩定直接放大電磁波所致。 -
Abstract : biological invasions are a continuous feature of a non - equilibrium world, ever more so as a result of accidental and deliberate introductions by mankind. while many of these introductions are apparently harmless, others have significant consequences for organisms native to the invaded range, and entire communities may be affected. here we provide a survey of common models of range expansion, and outline the consequences these models have for patterns in genetic diversity and population structure. we describe how patterns of genetic diversity at a range of markers can be used to infer invasion routes, and to reveal the roles of selection and drift in shaping population genetic patterns that accompany range expansion. we summarise a growing range of population genetic techniques that allow large changes in population size ( bottlenecks and population expansions ) to be inferred over a range of timescales. finally, we illustrate some of the approaches described using data for a suite of invasions by oak gallwasps ( hymenoptera, cynipidae, cynipini ) in europe. we show that over timescales ranging from 500 10000 years, allele frequency data for polymorphic allozymes reveal ( a ) a consistent loss of genetic diversity along invasion routes, confirming the role of glacial refugia as centres of genetic diversity over these timescales, and ( b ) that populations in the invaded range are more subdivided genetically than those in the native range of each species. this spatial variation in population structure may be the result of variation in the patchiness of resources exploited by gallwasps, particularly host oak plants
文摘:生物入侵是不均衡世界的一個永恆話題，尤其是當人類有意或無意地引入物種后.很多引入顯然是無害的，但另外一些則有著嚴重的後果，會給入侵地的生物以至於整個生物群落造成影響.本文總結了分佈區擴張的常見模式，概述了它們對遺傳多樣性和種群結構式樣所造成的影響.描述了如何根據以一批遺傳標記所得到的遺傳多樣性式樣來推斷入侵途徑，來揭示伴隨擴張選擇和漂變在形成種群遺傳樣式中的作用.本文對日益增多的群體遺傳學方法進行了總結，這些技術可以用來在不同的時間尺度上推斷種群規模所發生的巨大變化（瓶頸效應及種群擴張） .最後，我們以歐洲櫟癭蜂（膜翅目，癭蜂科，癭蜂族）一系列入侵的數據為例對一些方法進行了說明.從500 10000年的時間尺度上，多態的等位酶位點上等位基因頻率的數據表明: 1 ）遺傳多樣性沿入侵路線呈不斷下降的趨勢，支持了冰河期避難所作為遺傳多樣性中心的作用; 2 ）入侵地區的種群與該物種原產地的種群相比，遺傳上的分化更為強烈.這種種群結構在空間上的變異可能是被櫟癭蜂開發的資源尤其是櫟樹寄主在斑塊上出現變異的反映 -
The movement of the satellites causes doppler frequency to drift, the receiver usually tracks the signal frequency the receiver through phase locked loop, in order to can demodulate the signal
衛星運動造成多普勒頻率漂移，接收機一般都採用鎖相環來跟蹤接收信號頻率，以便能正確解調信號。 -
The time base drift deduced by the change of temperature is discussed particularly and the compensation method of it is analyzed. finally, we also studied frequency band extension under time base distortion condition by simulation. the results show that the compensation of time base distortion can reduce the error of signal and then increase the accuracy of frequency band extension
首先，介紹時基失真的相關概念及其對測量信號的影響；其次，對時基失真特性測量的不同方法進行了理論分析和比較，並對分析信號法進行了模擬研究；再次，對時基失真的補償方法進行分析和模擬研究；並專門對溫度變化引起的時基漂移及其補償方法進行了簡要分析；最後，對時基失真條件下的頻帶展寬技術的模擬表明時基失真的補償可以減小信號的誤差，因而提高頻帶展寬的精度。 -
The emphasis was put on the main factors affecting its performance, such as : drift of the average frequency of interferometer ; drift of frequency difference of interferometer ; the changes of the interference add - on term of the gaussian beam during the measurement and its effects on the phase changes, as well as the relationship between the changes of the interference add - on term of the gaussian beam during the measurement with the movement of the measurement mirror
對雙頻激光干涉儀的工作原理進行了理論分析，著重分析了其主要影響因素：雙頻激光平均頻率漂移；雙頻激光差頻漂移；高斯光束干涉附加項在測量過程中的變化及其對相位變化的影響，與測量鏡運動引起的程差變化的關系。 -
To compensate for low - frequency drift of the optical path - length difference and to keep the operation point on the most sensitive point, the reference mirror is adjusted with a actuator driven by a feedback loop
為了補償光程差的低頻漂移，將工作點穩定在靈敏度最高點，使用一個反饋控制系統驅動微位移器調整參考平面鏡。 -
The phase detecting error caused by local oscillator frequency drift and non - synchronization of measurement signal and gate signal is eliminated and the measurement speed is improved at the same time
該方法可以有效的消除因本振信號頻率漂移及閘門信號與被測信號的非同步引起的測相誤差，同時提高了測量速度。 -
The mechanic character, destroying pattern, the ductile and dissipation energy capacity of this composite structure under the earthquake have been clarified. the stiffness degradation, natural frequency, damping ratio of this structural system with the development of intensity of earthquake have also been investigated. with consideration of the top displacement, drift of story and micro - strain of longitude steel bars, the equivalent shell wall method has been presented in order to simplify the design of such type structure
通過試驗，掌握了該結構體系在水平地震荷載作用下的受力特點、變形與耗能性能、結構的破壞形態等力學指標：得到了結構在不同地震烈度條件下的剛度變化、自振頻率、阻尼比等動力特性；綜合結構的頂點位移、層間轉角以及鋼筋的微應變，提出了適合於該結構體系簡化設計的「等效剪力墻法」 。 -
The pseudo - dynamic test of 1 / 3 - scale model six - story building assembled with hollow shear wall with seams. the internal forces, the deformation and the failure mechansm of the building under earthquake are studied. the rules of frequency, damping and response spectrum are studied. the characters of earthquake response such as structure displacement, interstory drift, action of earthquake, the amplificatory coefficient of acceleration and the rule of strain are discussed. at last, this paper presented the design method of this structure based on the aseismic style and put forward the construction
進行了帶縫空心剪力墻結構六層樓房的1 3模型的擬動力試驗，研究了結構在水平地震作用下的受力特點、變形特徵、破壞形態等力學性能；得到了結構在不同受力階段的頻率、阻尼、反應譜等動力特性變化規律；討論了結構各樓層的水平位移、層間位移、地震力、加速度放大系數及構件應力分佈規律等結構地震反應特徵；指出了結構的抗震類型、薄弱層及薄弱部位；提出了多層帶縫空心剪力墻結構的第一階段設計方法和相應構造措施。 -
Based the research on the laser beam drift feedback control technique, analysing the beam drift and its frequency components, a laser beam directional stability method is studied in the thesis in detail, with its measurement and control circuit system that combines the laser beam intensity modulation and the beam drift feedback control technique. in this method, at first the laser beam intensity is modulated with the acoustooptic modulator, then the lock - in amplifier is applied to detect and demodulate the modulating signal, at last a feedback control signal is generated by the dsp control circuit at last, including : 1
本文在原有的激光光束漂移量反饋控制準直技術的基礎上，對光束漂移量信號的數據和頻譜進行了分析，重點研究了一種集聲光調制光強與光束漂移量反饋控制準直技術於一體的激光光束方向穩定方法及其測控電路系統，該方法通過聲光調制實現光強調制，接著通過鎖相放大電路檢測並解調調制信號，然後通過dsp控制電路進一步對光束的漂移量進行反饋控制。 -
Both ip - iq approach and id - iq approach need low pass filters, as a result the accuracy of harmonic current detection is influenced by frequency drift. moreover, they both can only be used in three - phase power systems
I _ p - i _ q法和i _ d - i _ q法都需要低通濾波器，因而會使諧波電流檢測精度受到電源頻率漂移的影響，而且這兩種方法僅適用於三相電力系統。 -
It makes the analysis of signal twitter and modulation very easy and the measurement of frequency drift and converting very simple
它使信號的抖動分析、調制分析非常直觀，使頻率漂移測量、頻率轉換特性測量變得十分簡單。 -
This approach the problem of conquers phase excursion and frequency drift that anciently adopts fixed frequency filter and its frame is simple
這種方法克服了以往採用固定頻率濾波器帶來的相移和頻率漂移問題，而且結構簡單。 -
At the same time the temperature coefficient of a dr could be positive or negative, and this may be used to compensate for the frequency drift due to temperature shift
同時， dr的諧振頻率溫度系數可正可負，這可以大大提高dro的頻率溫漂性能。
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