頻率預選 的英文怎麼說
中文拼音 [bīnlǜyùxuǎn]
頻率預選
英文
frequency pre-selection-
Intermodulation suppression for fh ( frequency hopping ) receiver is designed by selecting the intermediate frequencies and changing group of filters, local oscillation ( lo ) frequency, bandwidth of lo frequency under the condition that receiver configuration, sensitivity, dynamic range, instantaneous bandwidth and precision of frequency measurement are fixed
摘要針對跳頻接收機的體制和靈敏度、動態范圍、瞬時工作帶寬、測頻精度等設計參數，通過改變預選器組成、本振頻率和本振帶寬，分析接收通道的中頻選取原則，以實現跳頻接收機的互調抑制設計。The raw materials, the composition, the time of milling, the calcining temperature, the different additives, the sintering temperature and the sintering parameters were investigated. the result showed : it was advantaged to obtain high initial permeability mnzn ferrite with stable frequency characteristic using high - purity raw materials ; in order to obtain mnzn ferrite with high properties, we must control strictly the composition ; it could improve the properties of mnzn ferrite by optimizing calcining temperature. the lower calcining temperature made the permeability higher, and the higher calcining temperature could promote the frequency characteristic of permeability ; we chosen the right time of milling according to the requirement of power diameter ; in order to improve the properties of mnzn ferrite, it is necessary to add effective additives. in this dissertation, the influence of bi2o3 、 moo3 、 k2co3 、 co2o3 were investigated ; the sintering temperature, the time of heat - retaining and sintering parameters were the key factors of preparing high permeability mnzn ferrites
研究結果表明:採用高純度的fe2o3有利於獲得高起始磁導率且頻率特性優良的鐵氧體;為了制備所需性能的鐵氧體，需要嚴格控制配方中各種原材料的含量，優化配方;由於粉體活性受預燒條件的影響，所以對不同要求的鐵氧體選擇的預燒條件就不一樣，適當降低預燒溫度有利於獲得較高的起始磁導率，而為了獲得良好的頻率特性可以適當地提高預燒溫度;根據對粉體顆粒粒徑的不同需求，可以選擇不同的球磨時間;而有效的添加劑是改善材料性能的必要條件，本文在添加劑的研究中主要對bi2o3 、 moo3 、 k2co3 、 co2o3的影響分別作了詳細地討論;燒結溫度、保溫時間和燒結氣氛是高磁導率mnzn鐵氧體制備最關鍵的工藝，適宜的燒結工藝可以獲得理想微結構和組成，從而得到高性能的鐵氧體材料;而從材料的微結構上來看，要提高材料的截止頻率，就要適當地細化晶粒、增加晶粒內部的氣孔。In the pre - procession of front radio frequency, the super - heterodyne technology which get proper a / d sampling rate through choosing a proper frequency and bandwidth is adopted
射頻前端預處理採用成熟的超外差技術，選擇合適的中頻和帶寬，得到合適的a d采樣速率。The paper proposes a feedback pre - equalization ( f - pe ) method based on channel estimation in a frequency - selective rayleigh fading channel
在頻率選擇性瑞利衰落通道條件下，提出一種基於通道估計的反饋?預補償均衡檢測演算法。This text completely and systematically studies the status and the development of the pyrolysis and the fluidization of biomass, which distill the bio - oil in the domestic and international area, as well as the existing problems. this thesis primarily include following aspects : ( l ), by experimenting and measuring the energy ( heat value ) and the content of c, h, n chemical element of right 20 kinds of common biomass, on the base of the experimental result, and respectively established the biomass energy predict experiment formula with the element of h and c is from change, and passed the ro. os examination, which provides the basis and convenience for flash pyrolysis fluidization device energy to convert the rate to compute with biomass energy utilization calculation ; ( 2 ), proceeded the tg and dtg experimentation equal velocity ( 10 ? / min, 20 ? / min, 40 ? / min, 60 ? / min ) heating and constant temperature heating by studying on eight kinds of biomass samples, according to the experimental data and arrhenius formula, we established the dynamics model of pyrolysis of, then, using the goast - redfern and p function, we also solved the dynamics parameters and analyze out every kind of biomass ' s frequency factor and parameters of activation energy, and established the every kind of dynamics model of pyrolysis of biomass, all of these provide the theories and basis to make sure the reactor ' s flash pyrolysis work temperature scope design and the describing of pyrolysis reactor dynamics ; ( 3 ), in order to study and ascertain the process of heat completely getting to pyrolysis time of varied size biomass particles, we observed and measured the ratio of length and diameter ( l / d ) with the varied biomass through electron microscope, we concluded the l / d ratios usually is from 5. 0 to 6. 0, the average is 5. 3 ; ( 4 ), we studied the process of biomass transiting and the theory of complete pyrolysis time with the theory of complicated heat field, we got the time ( t ) of the varied size biomass particles arriving to complete pyrolysis, and we knew that the complete pyrolysis time and the time which get to the biggest production ratio are identical, all of these studies provide the theory base for design and forecasting the flash pyrolysis reactor solid state resort time ; ( 5 ), according to the above experiment result, synthesize to make use of the engineering the mechanics, engineering the material, machine the design to learn the principle, deduce, establish the theory of rotation cone flash pyrolysis reactor material resort time ( t ) and reasonable rotation velocity ( or frequency ) relation theory ; and ( 6 ), we gave the reactor ' s smallest cone angle certain, reactor cone wall strength design theory, the reactor production ability theory, the power design method and the critical rotation velocity theory
本文較全面、系統地綜述了國內外生物質熱解液化制取生物燃油技術研究發展現狀及存在的問題，主要研究內容有： （ 1 ）實驗、測定了20種常見生物質的能量（發熱量）和c 、 h 、 n元素含量，根據實驗結果分別建立了以h和c為自變量的生物質能量預測經驗公式，並通過r _ （ 0 . 05 ）檢驗；為閃速熱解液化裝置能量轉化率計算和生物質能量利用率計算提供了依據和方便； （ 2 ）選擇了8種生物質試樣作了等加熱速率（ 10 min 、 20 min 、 40 min 、 60 min ）和恆溫加熱的tg和dtg實驗，根據實驗數據和阿倫尼烏斯公式建立了生物質熱解反應動力學微分方程，並採用goast - redfem積分法和p函數對其動力學參數進行了求解，解析出各種生物質的頻率因子和活化能參數，進而建立了各種生物質的熱解動力學模型，為科學確定反應器的閃速熱解工作溫度范圍及熱解反應動力學描述，提供了理論和依據； （ 3 ）為研究和確定不同尺度的生物質顆粒中心達到全熱解的時間，在體視顯微鏡下對不同粒度的生物質顆粒的長徑比進行了實驗觀察和測定，得出生物質的長徑比（ l d ）一般在5 . 0 6 . 0之間，平均為5 . 3的結果； （ 4 ）採用復雜溫度場傳熱學理論對生物質傳熱過程及充分熱解時間理論進行了研究，解析推導出了不同尺寸生物質顆粒中心溫度達到充分熱解溫度的時間（ t ） ，得出了理論推導的充分熱解時間與最大產油率的熱解時間相一致的結果，為閃速熱解反應器固相滯留時間設計和預測提供了理論依據； （ 5 ）根據上述實驗結果，綜合運用工程力學、工程材料、機械設計學原理，推導、建立了轉錐式閃速熱解反應器物料滯留時間（ ）與轉速（或頻率）合理匹配理論； （ 6 ）提出了轉錐式閃速熱解反應器的最小錐角設計、錐壁強度設計、生產能力設計理論和功率計算方法及臨界轉速理論等。The paper studies the theory and coding methods of the low bit rate video recommendation h. 263 + detailedly, realizes real - time software codec based on h. 263 + under linux os, furthermore, finishes some negotiable coding options which can observably improve the coding efficiency, such as advanced prediction mode, advanced intra coding mode, deblocking filter mode and modified quantization mode
263 +的原理和編碼方法做了深入的研究，軟體實現了基於h 263 +標準的視頻編譯碼器在linux操作系統下的實時編解碼，並實現了能顯著提高編碼效率的幾種可選編碼模式，主要包括先進預測模式、先進幀內編碼模式、塊邊界濾波模式和改進量化模式等。The adaptive front - end has the adaptive ability for the magnitude and frequency of input signals. it can prefilter for the input signals, eliminate the useless signals, and improve the dynamic range of receiver system. it can lessen the burden of digital signal processing in the back - end of receiver, and improve the performance of receiver system
自適應接收機前端對輸入信號有自適應能力? ?頻率自適應和幅度自適應，這樣的前端就可將系統的接收中心頻率和帶寬自適應到輸入信號的頻率和帶寬，其實就是對輸入信號進行一次預分選、預濾波，剔除對接收系統毫無作用的信號;同時對大信號自動減小增益，對小信號增加增益，提高系統的動態范圍;而且可以對干擾信號進行壓制。This thesis discussed approaches of fault diagnosis based on the sensitivity analysis which is a new test method of analog circuits. main objects are described as follows : first, there exists a problem which the existence of solutions can not intuitively be predicted by choosing test frequency in the first - order sensitivity method on fault diagnosis
在此理論基礎上，本文從以下兩個方面進行嘗試:首先，一階靈敏度故障診斷方法存在這樣一個問題，即測試頻率的選擇不能直觀地對故障診斷方程解的存在性進行預分析。The result of study on the factors affecting the transformation frequency showed : the leaf disc was pre - cultured for 2 days, infected for 20 minutes, co - cultivated with agrobacterium eha105 for 2 days, which could improve regeneration efficiency. the highest regeneration efficiency was 13. 3 % in this experiment
實驗結果表明：葉片預培養2d ，農桿菌浸染20min ，與農桿菌共培養2d時，篩選培養基上洋桔梗葉盤不定芽分化頻率最高，達13 . 3 。This scheme not only decreases the lattice reduction complexity but also presentes a good detection performance. at last, based on the research of mimo precdoding techniques under the flat
最後在對平坦衰落通道下mimo預編碼技術研究的基礎上，開展了準靜態頻率選擇性通道下預編碼技術的研究。Firstly, based on the c6711 dsp hardware characteristics, h. 263 was chosen as the core video compression framework. after seven advanced options of h. 263 was tested, we analyzed the test results and used three options which are unlimited motion vector, advanced motion prediction and deblock filter as the scheme of the low bit - rate monitor video encoding
首先，通過對目前的低碼率視頻編碼技術的分析，結合c6711硬體特點，我們選擇了h . 263視頻編碼標準作為監控視頻編碼框架，並且通過對h . 263標準的七個高級編碼選項的測試和分析，選取了其中無限制運動矢量、高級預測和去塊濾波等三個編碼選項作為監控視頻編碼的主要方案。1. nizn ferrite was developed for using in mini high frequency dc - dc converters and inductors. we measured and analysed the parameters of the nizn ferrite, which we concern about when designing the dc - dc converter. 2. the low loss sample of nizn ferrite were chosen for design - optimization of the high frequency transformer. based on the relevant theoretical researches, the loss properties of the magnetic core material and winding were analyzed in this thesis
因此，以nizn功率鐵氧體材料為開關電源芯材為基礎，並優化各種開關電源的設計已成為國際上的熱點和技術瓶頸，本論文正是以上述背景為研究目標而開展工作的，主要進行的工作和創新有: 1 .對研製的新型高頻低功耗的功率nizn材料進行參數的測試，並針對dc - dc變換器設計關心的參數對芯材特性進行了分析，選擇在特定頻率下，功耗較小的nizn材料磁芯樣品作為變壓器優化設計的預備磁芯。Electromagnetic interference prediction in integrated communication command system
電磁干擾預測在頻率方案選擇中的應用We chose suitable tcp throughput model to estimate the available bandwidth correctly, using the estimated round trip time and packet loss ratio for the next time interval as parameters of the model to achive the accuracy of estimated network bandwidth. as the observed losses and round trip time vary very dynamically, adjust the sending rate equivalent to the amount of tcp throughput may result in a rather fluctuant sending rate. so we present a rate adjustment like tcp congestion control based on aimd, which increases its sending rate by an additive inereease rate
根據mpeg4視頻流應用的特點，選擇合適的吞吐量模型，進行合理的參數估計，並根據計算出的帶寬進行相應的速率調整來實現擁塞控制，我們使用未來rtt的估計值和分組丟失率的估計值作為吞吐量模型的參數，增強了控制的實時性，弱化了業務的振蕩性，提高了帶寬預測的準確性；在進行速率調整時，不是簡單地將發送速率調整到與tcp吞吐量模型一致，而是採用類似tcp的aimd策略來調節發送速率，減小了發送速率的振蕩性。This article proposes the adaptive algorithm based on equal snr signal noise ratio, and applies it in adaptive ofdm system. in frequency selective fading channel, compared with the traditional ofdm system based on equal power allocation, the system outperforms in ber bit error ratio performance
提出了一種基於最小平均誤碼率的自適應預處理演算法，並將該演算法應用於自適應ofdm系統，在頻率選擇性衰落通道條件下，與等功率分配的ofdm系統相比，誤比特性能有了很大程度的提高。The problem of signal processing for direct - sequence code - division - multiple - access ( ds - cdma ) signal over multipath frequency - selective mobile channels is considered. a new blind receiver is proposed. without the knowledge of the multiple - access interference users spreading code and the channel characteristics, the receiver achieves blind detection with prior knowledge of only the desired users spreading code and approximate timing. by using reduced rank adaptive decorrelating filter and adaptive multipath combiner which is based on decision - directed algorithm, the receiver gets the ability to combat both fading and the near - far effect at low cost. simulation results demonstrate that the proposed receiver offers high performance
本文研究多徑頻率選擇性衰落通道下直接序列擴頻碼分多址（ ds - cdma ）信號的處理問題，提出了一種新型的盲接收機.該接收機不需預知多址干擾用戶的擴頻碼，不需預知通道參數，只需已知期望用戶的擴頻碼和粗略的定時，就可以完成用戶的盲檢測.同時，該接收機通過降維自適應去相關濾波和基於判決指導的自適應多徑合併，來獲得低成本和良好的抗衰落、抗遠近效應性能.模擬結果驗證了本文提出的接收機的優良性能分享友人