最大調變頻率 的英文怎麼說
中文拼音 [zuìdàdiàobiànbīnlǜ]
最大調變頻率
英文
maximum modulating frequency-
And then facing the problem of the channel estimation of the adaptive modulation system, we conclude out the channel estimation algorithms on maximum likelihood ( ml ) estimation and maximum a posteriori ( map ) estimation under the condition of flat fading channel and selective fading channel in detail. to meet flat fading channel, we simulate the relationship of the ratio between the error covariance in map estimation and ml estimation and pilot symbol message length. the conclusion can be drawn from these results
接著，對自適應調制系統中的通道估計問題難點，詳細推導了平衰落通道條件下和選擇性衰落通道條件下最大似然（ ml ）估計和最大后驗概率（ map ）估計演算法，針對平衰落通道，我們模擬了map估計和ml估計的方差與導頻符號長度的關系，模擬結果表明，錯誤方差受多譜勒頻率的變化影響最大，並且對實際的自適應調制系統，導頻符號長度的取值超過20個符號長度時， map通道估計明顯優于ml通道估計。The modulation of sound properties over a wide range of time scales is one of the most obvious characters of oscine passerine ' s vocal, whose song contains many different kinds of syllables that consist of many more multiple song phrases. in oscine passerine, ipsilateral projections of ra to nxiits innervates the ipsilateral syringeal muscles exactly, and thus they have strong ability of vocal control with variable tones, high frequency and higher lever of quality. as a result, the songs sound well
鳴禽鳴囀的最大特點之一便是其單次鳴唱時間長，鳴唱所包含的音節數量和音節種類繁多，因而由這些音節所組成的句型結構也是復雜多樣富於變化，且由於nxiits嚴格的側別控制（每一側核團只支配同側鳴肌） ，使其具有更強的控聲能力，其鳴聲音調變化幅度大，頻率高，品質因數大，音色好，因而其鳴聲也悅耳動聽。Corticofugal modulation of frequency tuning of inferior collicular neurons in big brown bat, eptesicus fuse us chinese science bulletin, 2000 in order to explore the possible mechanism of corticofugal modulation of excitatory frequency tuning curves ( eftcs ) of midbrain neurons, we examine the change of sharpness, frequency - intensity response area, minimum threshold of both eftcs and inhibitory frequency tuning curves ( iftcs ) of inferior coliicular neurons during corticofugal modulation using two - tone inhibition paradigm and micro - electrical stimulation technique
第二章大棕幅聽皮層對中腦下丘聽神經元頻率調諧曲線的調制科學通報， 2000用雙聲刺激的方法和電刺激技術，進一步研究了在激活聽皮層前後下丘聽神經元興奮性和抑制性頻率調諧曲線的銳度、頻率強度反應區域、最低閾值的協同變化In view of this situation this article has conducted research to the design of metallurgy auxiliary biography with the frequency conversion table electrical machinery first multianalysis to the frequency changer and the frequency conversion table electrical machinery movement characteristic is carried out, the voltage waveform harmonious which the frequency changer outputs is big, attacks in a big way, and the voltage climbing rate reaches as high as 6600v / mu s which is 20 times ordinary sine alternating voltage, the rolling mill auxiliary biography table set the extremely strict request to the electrical machinery ; its movement frequency is very low, rate frequency in 8 - 20hz ; the velocity modulation scope is wide, the lowest movement frequency lowers to 1hz, and the starting number of times is quite frequently, each hour reaches as high as 600 - 800 time, the impact shoulders in a big way, the overload capacity request is high
針對這一情況本文對冶金輔傳用變頻輥道電機的設計進行了系統研究。首先對變頻器和變頻輥道電機的運行特性進行詳細分析，變頻器輸出的電壓波形諧波大，沖擊大，電壓上升率高達6600v / s ，是普通正弦交流電壓的20倍;軋機輔傳輥道對電機提出了十分嚴格的要求:其運行頻率很低，額定頻率在8 - 20hz ;調速范圍寬，最低運行頻率低到0 . 5hz ，起動次數相當頻繁，每小時高達600 - 800次，沖擊負荷大，過載能力要求較高。And the most advantage of ofdm is that it can convert high - rate data stream into the low - rate and reduce data bandwidth so that multi - path - fading can be transformed into flat fading in wireless circumstance
這種調制技術的最大的好處就是將高速的數據流，變換成并行的低速數據流，減小了數據帶寬，從而可將無線環境中的多徑衰落（頻率選擇性率落）轉換成平坦衰落。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。There are five parts are as follows : in part one, the concept of switching function is introduced first to establish the nonlinear mathematical model of the induction motor variable frequency speed adjustment system which is fed by a sine pulse width modulated ( spwm ) inverter and takes the effect of the main magnetic circuit saturation into consideration, then the low frequency oscillation of the system is simulated according to the model. next, from the view point of energy conversion of the inverter - induction system, a criterion for the low frequency oscillation is proposed to determine whether the system is in low frequency oscillation which is judged by whether the interval of the negative current component of the inverter input current is more than 1 / fc ( fc is the carrier wave frequency of the inverter ) or not
首先引入開關函數概念，建立了正弦脈寬調制（ spwm ）逆變器供電異步電動機，考慮主磁路飽和時的變頻調速系統整體數學模型，模擬系統的低頻振蕩；其次從逆變器-異步電動機系統能量轉換角度出發，提出通過檢測逆變器輸入電流中負電流的間隔時間是否大於1 / f _ c （ f _ c為逆變器載波頻率）來判定系統是否出現低頻振蕩；最後的實驗結果驗證了系統低頻振蕩建模和判據的實用性和正確性。Due to the complexity of the structure and control of cycloconverter - type three - phase hf link inverter for soft - switching based on phase - shift - controlled full - bridge mode, a simple and optimized vvvf control strategy is proposed. this control strategy includes : produced pwm by space voltage vector ( svm ) and equivalent carrier frequency fe = 1 / te are introduced into the pdm control of the cycloconverter ; softened equivalent pwm wave is generated at the notches of hf voltage pulses ; the harmonious control between regulating pulse width by phase - shifted angle and regulating voltage of equivalent pwm is to minimize the harmonics content of output voltage of the inverter
西安理工大學博士學位論文針對這種前級移相全橋軟開關周波變流型三相高頻鏈逆變器結構和控制的復雜性，提出了一種實現簡單而整體優化的vvvf控制策略:將空間電壓矢量產生p姍的方法svm和等效載波頻率fe = 1 / te引入到周波變流器的pdm控制;按高頻電壓脈沖前後沿軟化等效p翎波;用移相調節高頻脈沖寬度和等效p姍調壓協調控制逆變器輸出電壓，在滿足輸出電壓條件下使諧波最小。Based on the analysis of commercial banks " current concept about fund management, this paper brings forward that fund management is the main - string in its operation, and that the concept of fund management, including security and profitability, is extended from current " forrying fund " to the management of the fund cost and fund risk the paper comprehensively discusses the principle of fund management, the management of fund costs, the tactics of management about fund liquidity, the measures of management about fund risks and how to solve the problems on interest risk in the period of frequent interest fluctuation. the paper puts forward ideas on how to improve the fund management. the security, liquidity and profitability of the fund, which are both contradictory and integrated with one another, are internal factors of fund management. fund liquidity is traditional core question. commercial banks face with a number of risks of witch credit risk is the greatest one because our country has adjusted interest rates 8 times since 1996, which covered a period of frequent interest fluctuation
商業銀行面對許多風險，但最大風險是信用風險。由於我國自1996年以來已連續調整了8次利率，近幾年是利率波動頻繁時期，研究利率的敏感性問題顯得特別重要。要改善資金管理，提高商業銀行的經營水平，就要建立資金管理是商業銀行經營主線的理念，對資金要統一規劃和管理；要改革銀行的體制，建立現代企業制度和法人治理結構，在體制上為資金管理提供有利的運行平臺；增加改善資金流動性管理所需的貨幣政策工具，擴大資金調控手段；打破貨幣市場的僵化局面，為資金管理創造有利的宏觀環境；續續優化負債結構和負債載體設計；增強資金信用風險規避和化解的措施；通過銀行資源整合，努力尋找資金的安全投放渠道，最終完成經營模式由傳統型向現代型的轉變。At the doppler centroid aspect, this paper make use of maximum value method ; energy method and autocorrelation function method to estimate doppler centroid. at the doppler frequency aspect, this paper make use of image offset method ; time - frequency method ; minimum entropy and fractional fourier transformation method to estimate doppler frequency rate
在多普勒參數估計中，採用了最大值法、能量法和自相關函數法進行多普勒中心頻率估計;採用了圖像偏移法、時頻分析法、最小熵法和分數階傅里葉變換法進行多普勒調頻斜率估計。Secondly, to achieve the independent regulation of active and reactive power output from the generator side which is designed for the purpose of tracing the maximum wind - energy capturing. the paper has analyzed the mathematic model of the ac excited doubly - fed machine and the stator field orientation control strategy of the motor as vscf wind power generator. thirdly, it has put forward and designed the dual pwm converter with the capacity of energy flowing bidirectional aimed at the demand of rotor energy bidirectional flow. the author constructed reliable and integrated experimental system and did a series of experimental study including no - load, cutting - in network and power generation at, below and above the synchronous speed
論文首先分析了風機運行特性及其最佳風能利用原理，通過模擬及實驗驗證了採用直流電機的輸出特性模擬風力機的最大輸出功率曲線的可行性，並給出了模擬系統的硬體結構；然後為了實現交流勵磁發電機有功、無功功率獨立調節機理，分析了交流勵磁雙饋發電機的數學模型和在追蹤最大風能捕獲變速恆頻風力發電時必需的定子磁鏈定向矢量控制策略；針對雙饋發電機轉子能量雙向流動的要求，提出並設計了具有能量雙向流動能力的雙pwm交流勵磁用變頻器；最後為實現從理論到實踐的全面研究，研製出了一套小功率完整的雙pwm變頻器交流勵磁的雙饋風力發電機實驗系統，進行了空載、並網、同步速及上、下的發電運行等一系列的運行實驗；所完成的模擬和實驗研究均驗證了理論、模型和控制策略的正確性、可行性。The system is based on chopper constant current drive technique, according to the top level design idea, adopting advanced specical subdivision control integrate circuit and powerful function 80c196kc to organize the system frame, desiging the minimum system of single - chip microcomputer, multifunction i / o interface circuit, relay switch circuit, keyboard and display circuit, multifunction digital setting interface circuit and so on, utilizing the hso and hsi interface circuit which are owned by this single - chip microcomputer exclusively and its powerful command system to realize dual - degree switch control, automation orientation, automatically searching zero position, locking machine when stopping, frequency to set digitally, automatically adjusting speed through changing frequency, swithing subdivision or squarewave control, on the basis of above, the system also have the function of running according to the setting steps and the frequency, voltage and current to display through the led, etc
系統基於斬波恆流驅動技術，按照頂層設計思想，採用先進的專用細分控制電路和功能強大的80c196kc單片機來組建系統構架，設計了單片機最小系統、多功能i o介面電路、繼電器切換電路、鍵盤顯示電路和多功能數字設定介面電路等，利用該單片機獨有的hso和hsi介面及其強大的指令系統，實現了雙余度混合式步進電動機的余度切換控制、自動定位、零位自動搜索、停機鎖定、數字化頻率設定、自動調頻變速控制、細分方波切換控制，在此基礎上，該系統還設有按預置步運行、 led頻率電壓相電流顯示等功能。22 paired inferior collicular neurons were obtained in the experiment. the neurons were recorded in the depth of 198 - 1254 u m ( 544. 59 ? 72. 37 n m, m + sd ), and their bfs were 11. 25 - 59. 29 khz ( 26. 77 + 9. 95 khz, m ? d ) : the minimum thresholds ( mts ) werelo - 66 db spl ( 38. 14 ? 14. 39 khz, m + sd ) ; the latencies were 4. 0 - 16. 0 ms ( 8. 19 + 3. 14 ms, m + sd ) ; the best intervals between paired sound pulses were 0. 01 - 28. 71 ms ( 3. 93 + 2. 52 ms, m ? d ) 0 the results showed : l ) there were interactions between the neurons in the iso - frequency lamina and hetero - frequency lamina which included mutual inhibition ( 18 / 22, 81. 8 % ) and mutual facilitation ( 4 / 22, 18. 2 % ), and the mutual inhibition in iso - frequency lamina was stronger than that in hetero - frequency lamina ; 2 ) the mutual inhibition decreased with sound level increasing ( p < 0. 001, anova ) ; 3 ) the analysis of the inhibition of discharge rate at lodb above mt showed that the inhibition increased when the paired neurons " bfs difference decreased ( r = - 0. 545, p = 0. 0006 ) ; 4 ) the mutual inhibition of paired neurons can sharpen the frequency tuning and the effect increased when the frequency was away from the bf ; 5 ) the changes in q10, q30 decreased with bfs difference of the paired neurons increasing ; 6 ) the mutual facilitation between paired neurons not only increased discharge rate, but also widened the frequency tuning, i. e., increased response frequency
結果表明： 1 ）同頻層神經元之間或者非同頻層之間神經元之間存在相互作用，這種作用既有相互抑制（ 18對，佔81 . 8 ） ，也有相互易化（ 4對，佔18 . 2 ） ，且同頻層神經元之間的相互抑制作用較非同頻層神經元之間的相互抑制作用要強； 2 ）神經元對低刺激強度反應時，所受到的相互抑制作用較強，隨著聲刺激強度加大，抑制作用逐步降低（ p 0 . 001 ， anova ） ； 3 ）對閾上10db放電率抑制百分比進行的分析顯示，配對神經元之間的最佳頻率差越小，相互抑制作用越強（ r = - 0 . 545 ， p = 0 . 0006 ） ； 4 ）配對神經元之間通過相互抑制作用可表kx碩士學位論文waiaster 』 sthesis現出調諧銳化作用，該作用的效率與頻率有關， bf處的銳化作用較低，偏離bf時其銳化作用逐步加強； 5 ）頻率銳化作用的效率與bf差有關，隨著配對神經元之間的bf差擴亢q10 ， q30值的變化逐漸減小，其變化百分比與配對神經元之間的頻率差存在明顯相關； 6 ）配對神經元之間的相互易化作用不僅表現在放電率增加上，也表現在頻率調諧曲線的擴寬，即頻率響應范圍擴大。This processing line has two sszm1200c straight line double edgers and 90 transfer table. 30 spindles on each sszm12000c, high collocated, wheels. high - level of polishing ; compact and steady base, precise and smooth transfermission system ; big power frequency - conversion motor to control the speed of pedeail ; plc control system sets processing parameters via interface, to control the width and the speed, the minimum size of the glass can be 127xl27mm ; the structure of the machines is compact and stable. this line is our new designed products, and it s the ideal choice of assistant equipment for exquisite and industrial glass, besides, it can be used with other machines to form a production line set
本生產線由2臺sszml200c玻璃直線雙邊機和1個90中轉臺組成每臺sszml200c玻璃直線雙邊機配置30個磨頭，磨輪配置多，加工拋光精度好底座穩重扎實，傳動系統精確流暢大功率變頻電機調速控制傳送皮帶驅動plc控制系統通過界面設定參數控制，最小加工玻璃寬度尺寸小至127127mm機器結構緊湊性能穩定，是我公司全新設計的力作是大批量精品玻璃和工業玻璃磨邊生產的暈佳配套設備，可口與夾膠印花，鋼化等生產線配套使用Sszm500b straight line double edgers, and 90transfer taboe. 26 spindles on each sszm2500b. plc control system sets processing parameters via interface, and finishes processing at one time. this product has stable structure. precise and smooth transmission system, thetransmission belt drive adopts strong power and transfrequency motor to control speed, constant power, constantrele output and advanced epuipment to control, high polishing efficiency. it is the best matched equipment of large batch of furniture and decorated glass edge production, and production, and can be matched with gluing, printing, reinforcing, etc. production line
才用plc控制系統通過界面設定加工參數一次完成加工，具有穩定扎實的底座結果精確流暢的傳動系統，傳送皮帶驅動採用大功率變頻電機調速控制，恆功率恆扭矩輸出和高配置的控制。結構緊湊，性能穩定可靠，拋光及生產效率高。是大批量的傢具和裝飾玻璃的磨邊生產的最佳配套設備，可以與夾膠印花鋼化等生產線配套使用。First, variable speed constant frequency wind energy convertion theory is described in this paper, then presents a review on the development of wind turbines control and the main types of generator and static converters used to interface variable speed wind turbines to the electric grid. then discuss main circuit constructure and advantage of direct drive wind energy conversion system and introduce pitch - control method for wind power traction and electric power stability. simply aerodynamic characteristic of the turbine is analysised and permanent magnet synchnonous generator math model is established. to convert the variable frequency electricity into utility grid, back to back four - quadrant pwm - vsi is used and three typies of control strategy is presented to capture the maximum wind energy and transmit energy. then simulation is implemented to test the control strategy. in the following chapter a simple ac - dc - ac converter with a dc - dc boosting chopper is proposed to transmit the wind energy into electricity energy and two control strategy is presented
建立了永磁電機和變流器的數學模型，針對雙pwm變頻器的特點提出了三種控制策略對變流器進行控制，通過變流器交-直-交的變換，將發電機發出的變頻變幅值交流電轉化為可用的恆定頻率的交流電，通過pwm調治能使其輸出功率因數為一，並且該控制系統功率因數為可調，能在特殊情況下同電網交換一定的無功功率，並通過對變流器的控制實現了最大風能俘獲的功能。最後採用matlab / simulink進行了模擬，取得了良好的模擬效果。在風力發電系統中，採用先進的最大功率俘獲演算法，能有效的從風中獲得最大的能量。The main technological characteristics include not only the integrated optimizing design of variable speed and constant frequency, ensuring the wind turbines to adapt to diversified wind plants with different temperatures and geographical conditions, but also the maximum wind power captured at optimized tip speed ratio below the rated wind speed and security protection of constant power output above the rated wind speed by variable pitch regulation
主要技術特點是整體綜合優化設計、變速恆頻運行、適合不同氣候特點和地理環境的風電場；風機全翼展變漿距功率調節、額定風速以下最佳變速比運行最大風能捕獲、額定風速以上恆功率輸出具有安全保護功能。Based on the torque - speed characteristic curve of induction motors, analyses were done on changes in slip with an variation in frequency when an induction motor drives different kinds of loads, including those with constant torque, constant - maximum torque, variable torque ( except fans and pumps ) and constant power, as well as fans and pumps, the formulas to calculate the slip and the speed under different frequencies and loads were presented
摘要以異步電動機機械特性曲線為基礎，分析了變頻調速異步電動機在拖動恆轉矩負載、恆最大轉矩負載、變轉矩（非風機和泵類）負載、恆功率負載以及風機和泵類負載時，轉差率隨頻率變化的規律。Future mobile communications have to support the transmission of high rate data and multimedia applications in the radio spectrum, which is already extremely scarce. the basic idea of adaptive coded modulation is to maintain a constant throughput by varying the transmitted power level, symbol transmission rate, constellation size, coding rate or any combination of these parameters. thus, without sacrificing bit - error rate ( ber ), these schemes provide high average spectral efficiency by transmitting at high speeds under favorable channel conditions, and reducing throughput as the channel degrades
自適應編碼調制（ adaptivecodedmodulation ， acm ）的基本思想是在不犧牲系統傳輸性能（比如ber ）為代價的前提下，通過單獨改變發送功率、波特率、編碼方案、碼率、調制方式，或者是綜合改變前面所述的各種參數，在有利的通道條件下，獲得較大的吞吐量，當通道質量下將時，相應地降低傳輸速率，最終達到提高平均頻譜效率的目的。分享友人