frequency diversity 中文意思是什麼
frequency diversity
解釋
頻率分集，頻率分隔，散頻-
This paper concerns studies on rhizobia in symbiosis with important legume soybean and peanut crops in china, following : 1 ) summarized bio - diversity of rhizobia, including indigeneous population, isolation frequency, strain type, distribution, and strain - host promiscuity and compatibility from large and small samples. 2 ) reviewed symbiont improvement in both sides of rhizobia and hosts, involving selection of effective rhizobial strains, evoluation and utilization of the host germplasm for symbiotic properties, and selection of the both sides for special characters. 3 ) discussed the subject on the rich symbiont germplasm resource in china and on further research being necessary to exploitation and utilization of the benificial germplasm
針對我國主要豆科作物大豆和花生的研究成果，並結合本身研究工作內容， （ 1 ）總結了與宿主共生的根瘤菌生物學多樣性，包括大、小樣本的土著根瘤菌群體數量、分離頻率、類型與分佈及其菌株宿主共生混交性與親和性； （ 2 ）評述了根瘤菌宿主植物共生體雙邊固氮改良，包括優良菌株的選育、宿主品種資源共生特性的評價與利用及特異性狀的選擇； （ 3 ）討論了我國這一類共生體資源的豐富性以及有必要進一步加大力度研究有益資源的開發和利用的問題。 -
Abstract : this paper concerns studies on rhizobia in symbiosis with important legume soybean and peanut crops in china, following : 1 ) summarized bio - diversity of rhizobia, including indigeneous population, isolation frequency, strain type, distribution, and strain - host promiscuity and compatibility from large and small samples. 2 ) reviewed symbiont improvement in both sides of rhizobia and hosts, involving selection of effective rhizobial strains, evoluation and utilization of the host germplasm for symbiotic properties, and selection of the both sides for special characters. 3 ) discussed the subject on the rich symbiont germplasm resource in china and on further research being necessary to exploitation and utilization of the benificial germplasm
文摘:針對我國主要豆科作物大豆和花生的研究成果，並結合本身研究工作內容， （ 1 ）總結了與宿主共生的根瘤菌生物學多樣性，包括大、小樣本的土著根瘤菌群體數量、分離頻率、類型與分佈及其菌株宿主共生混交性與親和性； （ 2 ）評述了根瘤菌宿主植物共生體雙邊固氮改良，包括優良菌株的選育、宿主品種資源共生特性的評價與利用及特異性狀的選擇； （ 3 ）討論了我國這一類共生體資源的豐富性以及有必要進一步加大力度研究有益資源的開發和利用的問題。 -
The synchronization and replication is also an essential technology of mobile database. comparing trade distributed database environment, mobile computing environment has characteristics of high frequency disconnection, network condition diversity, network communications dissymmetry and so on
移動計算環境與傳統的分散式計算環境相比有頻繁的斷接性、網路條件的多樣性以及網路通信的非對稱性等特點，這些特點使得傳統的分散式數據庫技術不能有效支持移動計算環境。 -
Lt is well anown that the multi ? ath effeet results in signal fading and intersymbol interference ( isd, wnich causes great difficulhes in pewces of transndssion in underwater acoushc cotnmnication. in this papef we used frequency diversity method to overcome the problem of signal fading, and used the frequency - hopping method to ebonate the isi caused by multi - path
水聲通道多途特性引起的信號衰落和碼間干擾是影響水下通信質量的主要因素，採用頻率分集技術可以處理幅度衰落，而跳頻技術則可以簡單、有效地抗多途引起的碼間干擾。 -
Comparing with the system which does not space - time code, space - time coding can obtain transmit diversity and increase channel capacity without frequency bandwidth loss
與空間未編碼系統相比，空時編碼可以在不犧牲帶寬的情況下起到發射分集和提高功率增益的作用。 -
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 backward scattering field of extended target is approximated as the synthesis of many strong scatter centers on target, and geometric optical method is used in establishing deterministic model of a aircraft in the paper, the model is used to evaluate the performance of frequency diversity in suppressing glint at last
本文將復雜目標後向散射回波近似為目標上若干強散射中心回波的合成，結合幾何光學法得到了某種飛機目標的確定性模型，並用該模型評定頻率分集對角閃爍抑制的改善性能。 -
At the same time, to achieve space, time and frequency diversity, some research is done on stf technology, which joints transmit diversity and ofdm technology
同時對發射分集技術和ofdm相結合，通過適當的編碼技術來獲得空、時、頻分集的空時頻編碼技術進行了一定的研究。 -
Frequency diversity technique is effective in suppressing age if the frequency interval is big enough to remove off the correlation between the pulses transmitted by radar, wide - band mmw radar can satisfy the requirement but conventional microwave radar can t
頻率分集技術抑制目標角閃爍的有效性，取決于去除脈間相關性的性能，即要求雷達發射信號必須有較大的頻率間隔，寬帶毫米波雷達正好滿足了這一常規微波雷達不能滿足的要求。 -
It is very difficult to design a high - quality underwater acoustic data transmission system. in our study, we use frequency diversity and frequency - hopped technology. this method is an effective solution for the isi and signal fading
該方法起到保證mfsk傳輸系統使用頻率中文摘要統使雨頻率分集技術能得以有效的實現；並可用於提高mfsk信號檢測精度，因此在頻率信號檢測中它有廣泛應用意義，它是本文重要創新之處。 -
The application of mc - cdma enables one to avoid isi and ici in the detection process, resulting in advantages of frequency diversity
由於在給定條件下，信號的峰平比是功放體積的決定性因素。 -
Furthermore, because the average power of transmitting lfmcw signal is the minimum peak power and the frequency diversity is high, it could not be detected easily
其次，由於lfmcw雷達發射其所需的平均功率是最小的峰值功率，並具有很高的頻率分集性，因此不易被偵察設備探測。 -
Finally, this thesis put forward the application of frequency diversity reception to the counteraction against the frequency selectivity decline in the airborne oceanic submarine laser communication system, and whose capability graph is educed through the simulation on the computer
文中提出把頻率分集接收技術應用於對潛通信中，以達到抗頻率選擇性衰落的目的，並通過計算機模擬得出了其性能曲線。 -
Space or multi - anntenna, diversity techniques are particularly attractive as they can be readily combined with other forms of diversity, e. g., time and frequency diversity, and still offer dramatic performance gains when other forms of diversity are unavailable
空間或多天線分集技術由於可以與其它如時間分集，頻率分集技術相結合，並在其基礎上提供很大的性能增益，而成為一種很有吸引力的分集技術。 -
Synchronization is the commander of every digital communication system, without it the system is unable to work orderly and correctly. a five - tuple of time - frequency diversity is adopted to guarantee that the synchronization signal be retrieved reliably in the receiver
同步是任何數字通信系統有序工作的「指揮棒」 ，本研究採用5重時頻分集的方法，使得在接收端能夠可靠地恢復出系統工作所需要的同步信號。 -
With this tech, we design a high - efficient & robust mfsk data transmission system. but in frequency diversity of mfsk system, it is very difficult to tell which diversity is the correct carrier frequency. now we use the temporary phase swift ( ips ) method to solve the difficulty
在2000年，美國海軍成功通過水聲鏈路並接入internet網路發送e mail ，這具有重要的戰略意義；從科學技術發展的角度來看是喜訊，但對我們這樣一個海洋大國來說，更現實的意義在於鞭策自己的科研工作。 -
It has been proven that the spread spectrum technologies have good capabilities of overcoming isi in electromagnetic wireless channel. the feasibilities of their applications to underwater acoustic channel have been analyzed, the frequency hopping technology is chosen. instead of using time - frequency diversity, convolutional coding and viterbi decoding are employed to combat signal fading, consequently the bit - rate and bit - error - rate performance of the underwater acoustic voice communication system can be balanced and controlled
由於擴頻技術在抗碼間干擾方面具有優良的特性，因此在分析了各種擴頻技術于本研究應用的可行性之後，確定了跳頻技術作為具體實現方案；在克服幅度衰落方面，選用卷積編碼和維特比譯碼方法來替代原有的分集技術以綜合調節系統的通信速率與誤碼性能，達到差錯可控的目的。 -
Because using ofdm, a frequency - selective fading channel can be transformed into multiple frequency - flat fading sub - channels, in the coding process, spatial diversity ( due to multiple antennas ) is integrated with frequency diversity ( due to delay spread ), therefore, the proposed code can provide higher diversity gain than space - time code alone
該編碼利用正交頻分復用把頻率選擇性衰落通道變換成平衰落通道的特性，同時引入了基於多天線的空間分集和基於時延擴展的頻率分集，比空時編碼具有更高的分集增益。 -
And diversity is a technique of extensive use and maturation, a technique of more inexpensive investment with more improvement in wireless communication. the common diversity be classified as space diversity, polarization diversity, frequency diversity, and time diversity etc. this paper focus on implement of space diversity and polarization diversity in digital field
無線傳輸在自然界中存在大量不相關的多徑信號，分集技術是通信中的一種廣泛應用的、成熟的技術，一種用相對較低廉的投資就可以大幅度的改進無線鏈路性能的強有力的接收技術。 -
In this part, the two anterior chapters mainly discuss the various basic theories used by the designing for the propagation paths of the electric wave. the theories include the computation methods for the fade and the loss of various propagation paths and obstructions, the engineering estimation methods of the flat fading and frequency selected fading, the designing methods of space diversity and frequency diversity, etc. at the same time, the special designing method of the sea - across path is discussed in detail
本文首先闡述了微波中繼通信工程設計中的相關知識，其中前兩章主要論述了線路設計中所用到的種種理論基礎知識，包括對于各種路徑情況、障礙情況的衰落與損耗的不同計算方法，平衰落與選擇性衰落中斷率的估算方法，天線分集和頻率分集技術的理論知識和設計方法等等。
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