symmetrical system 中文意思是什麼

The control system with such method is simulated and a inverter is made for speed control of single - phase motor. the method presented in this paper offers such advantages as easy implementation, large range of frequency and rapid dynamic response. furthermore, using this method, the single - phase motor with symmetrical or dissymmetrical windings can operate symmetrically

本文提出的變頻調速控制方法具有系統設計簡單易實現，調速范圍大，動態響應快等特點，而且在電機繞組對稱和不對稱兩種情況下均可實現變頻調速的對稱運行。

In power system full dynandc simulation software, the adndttance matrixes of fault branches are adopted in the fault models to simulate arbitrary symmetrical and unsymmetrical faults, by use of contraction technique for adndttance matrix the multi - faults and the randomly occurred faults can be processed. the feature of this method is that the arbitrary multi - fault occurred in a branch can be simulated without any additional branches or buses to be added, thereby, the ca1culation efficiency and the expedience of usage are improved

本文提出採用故障支路導納陣處理復故障計算，該演算法可以對一條支路發生任意重故障進行處理，而不需要增加支路或節點，克服了目前常用的電力系統機電暫態程序在處理復故障時，一般要按照事先預想的故障類型以及故障和操作發生的位置增加新的節點和小開關支路的問題。

The primary research contents are summarized as follows : 1. vpn cryptographical system is concerned with cryptographical technology, authentication technology and vpn implementation protocols. symmetrical cryptographical algorithms, non - symmetrical cryptographical algorithms and domestic cryptographical algorithms are discussed

研究的主要內容包括以下幾個方面： 1 、 vpn密碼系統的構建涉及幾個方面的技術，包括加密技術、認證技術、實現協議等。

A friction drag testing system for the underwater axi - symmetrical vehicle model

一種軸對稱水下航行器模型摩擦阻力測試系統

Accurate mathematical model is set based on the whole system, and simulator program of dynamic and steady condition is established, which is use to calculate the dynamic and steady performance by kron and symmetrical coordinate converter

論文通過對電機基本方程進行kron變換和對稱分量變換，分別建立了系統完整的數學模型，編制了動態和穩態模擬程序，並對系統進行了模擬，對系統的動態、穩態性能進行分析。

The study has completed the design of two - phase inverter and made up of the two - phase inverter - motor system for experimental use it is a variable frequency adjustable speed system with a open - loop control of rotational speed, which consists of voltage - controlled oscillator circulating assign device inverter circuit and two - phase induction motor a accurate mathematical model is set based on the whole system, and simulator program of dynamic and steady condition is established, which is used to calculate the dynamic and steady performance by kron and symmetrical coordinate converter by simulator calculation and experimental research with specific parameter of the system, a comparison is made between predicted and experimental characteristics, experimental measurements are shown to compare closely with corresponding theoretical result it is compared with some variable frequency adjus table speed system comprising inverter and single - phase induction motor from the system efficiency torque pulsation and the effect of two - phase inverter capacitance based on the conclusion, harmonic cancellation pulse width modulation control of a two - phase inverter - fed induction - motor drive system is researched, which cancelled the low harmonic and improve the system performance

通過對電機的kron變換和對稱分量變換，建立了系統較精確的數學模型，編制了系統動態及穩態運行的模擬計算程序分別計算系統的動態和穩態性能。通過對系統的具體參數進行了模擬運算和實驗研究，實驗和模擬結果進行比較，說明實驗和理論較為一致，並從系統效率、轉矩脈動及兩相逆變器電容的影響等方面與各種逆變器和單相異步電動機組成的變頻調速系統加以比較。在此基礎上，對兩相逆變器供電-異步電動機系統使用諧波抑制pwm控制進行了研究，由於減少了低次諧波，改善了系統性能。

In order to utilize the frquency resource adequately and increase the capacity of mobile communication system, the wireless electric wave propagation of existing mobile system always adopts the microcell structure. forecasting the path loss characteristic of electric wave accurately can provide the necessary condition for the layout and design of wireless network, at the same time it is a precondition for the research on the microcell mobile system. the methods of forecasting of wireless electric wave propagation can divide into two parts : one is pluse and respond, that is establish the empirical model based on experimental and statistical data ; the other is ray tracing method, that is establish the deterministic model based on theoretical analyse. the paper discuss the characteristic of wireless signal electric wave transmition in symmetrical atmosphere of earth, and introduce the common path loss transmition model in land mobile communication system, also point out the localization of these models based on experiential methods

而精確預測無線電波傳播路徑損耗特性，則為合理的微蜂窩無線網路規劃、設計提供了必要條件，同時也是研究微蜂窩移動通信系統性能的前提。無線電波傳播預測的方法分為兩類：一是用沖激響應法，即根據實驗、統計所得數據建立經驗性傳播預測模型；另一種是用射線跟蹤方法，即依據理論分析來建立確定性的傳播預測模型。本文首先討論了在地球表面均勻大氣中的無線電波傳播的基本特性，介紹了陸地移動通信系統中常用的幾種電波傳播路徑損耗經驗性預測模型，並指出了這些經驗性傳播模型對于微蜂窩小區無線電波傳播特性研究的局限性。

Accordingly ray tracing model for microcells propagation prediction has become an important subject. this paper discussed the characteristic of propagation in symmetrical atmosphere on the earth, and introduced several kinds of traditional path loss propagation model in land mobile communication system, also pointed out the localization of these models based on experiential methods

本文首先討論了在地球表面均勻大氣中的無線電波傳播的基本特性，介紹了陸地移動通信系統中常用的幾種電波傳播路徑損耗經驗性預測模型，並指出了這些經驗性傳播模型對于微蜂窩小區無線電波傳播特性研究的局限性。

The stability of electric power system has been being focused for a long time toprevent a power system from losing synchronism after sudden fault ， researchers have done much work and got many accomplishments this paper applied the direct feedback linearization ( dfl ) technique on the power system ， a strong nonlinear system simulation results by matlab proved this method efficiency main works and results are as follows ： this paper compared some existing methods in excitation control ， fast valve control and coordinated control respectively, analyzed the developments and actuality of nonlinear control research in brief, illustrated why ransient stability could be greatly improved by using the fast valve control in chapter 3 ， indicated the importance of coordinated control farther this paper introduced the inverse system theory, based on which ， discussed the dfl theory, pointed out which had consistency with the inverse theory, expanded the dfl theory combined the idiographic model equations ， made which adapt to the model of a single machine - infinite bus power system this paper referenced abundance articles and educed a set of equations ， which could describe the dynamical process of excitation and fast valve control for synchronous generators in the equations ， there were several very important parameters of power system - - rotor angle ( ) ， rotor speed ( ) ， generator q axis voltage ( eq ) ， transient voltage ( e ' q ) ， active power ( pe ) ， mechanical input power ( pm ) ， valve opening ( ) ， generator terminal voltage ( vt ) ， based on the model ， nonlinear coordinated controller and terminal voltage optimal controller have been designed by using the expanded dfl theory and lq optimal control theory the simulation results showed that the controller could keep power system transiently stable under the effects of a symmetrical 3 - phase short circuit fault ， which achieved better postfault regulation compared with another two routine methods ， one is the proportion excitation controller and proportion fast valve controller, the other is the proportion excitation controller and the optimal fast valve controller, which could exert good performance when met 1ittle disturbance either

在介紹逆系統理論的基礎上，詳細介紹了dfl理論，通過比較闡明了dfl理論其本質是逆系統方法的一類，並結合具體課題推導出的模型方程將dfl理論進行了擴展，使之適應于電力系統這個強非線性對象。通過參考大量的書籍文獻推導出一套實用的可將大型汽輪發電機勵磁與汽門綜合起來進行控制的模型方程，此模型方程涵蓋了電力系統中特別引人注目的幾個量- -轉子角、轉子轉速、發電機q軸電勢eq 、暫態電勢e ' q 、有功功率pe 、機械功率pm 、汽門開度、機端電壓vt ，在此基礎上建立了實用的電力系統簡化的數學模型，並將擴展的dfl理論應用於此模型系統，結合線性二次型最優控制理論設計出大型汽輪發電機的非線性綜合控制器及機端電壓最優控制器，通過模擬實驗與採用常規的按電壓偏差進行調節的比例式勵磁控制器+汽門比例控制及採用常規的按電壓偏差進行調節的比例式勵磁調節器和基於二次型性能指標設計的最優快控汽門（考慮發電機的飽和因素）進行了對比，證實了採用此種控制器可以有效地提高電力系統的暫態穩定性，並且在電力系統遭受小干擾時同樣具有良好的調節性能。

The antenna system has a good characteristic with wide symmetrical beamwidth, broad impedance bandwidth and compact structure

整個線性漸變槽天線系統具有對稱波瓣、寬頻帶、寬主瓣和結構緊湊等特點。

Compared with the fdd system, td - scdma adopting tdd, has no need of symmetrical frequency bands for uplink and downlink, and enables flexible and convenient planning and use of increasingly scarce spectrum resources

與fdd系統相比， td - scdma採用時分雙工方式，上下行無需對稱頻段，可以見縫插針，靈活方便地規劃使用日益緊張的頻譜資源。

The paper establishes mathematics model of electromagnetic heating system of eddy current field and temperature field, and gives corresponding discrete format with elements as eight nodes, hexahedron equal cell, through calculating eddy - current field to gain the internal heat source that the temperature field needed, to use discrete method to solve the problem of induction - heating part ' s temperature field by axial symmetrical electromagnetic, and then to analyze the characteristic of instantaneous temperature field

本文建立了電磁加熱系統的渦流場和溫度場間接耦合的數學模型，分析了不同頻率下渦流和溫度的分佈情況，並以八節點六面體等參元為例給出了渦流場對應的離散格式，通過計算渦流場獲得溫度場所需要的內熱源強度，加熱部件的溫度場以軸對稱格式進行離散求解，並對瞬態溫度場有限單元法的求解特點進行了分析。

Prototype of the symmetrical typical voltage space - vector of open - loop variable frequency speed system is designed by using the tms320f240 digital controller and the ipm ( intelligent power model ), with which had a exam on the motor and the experimental results are also given. from the results we can conclude that the results are according with the theory analysis

利用ipm智能功率模塊，設計了採用基於tms320f240數字控制器的對稱空間電壓矢量的開環變頻調速系統的原理樣機，對電機進行了空載實驗，給出了它們的實驗結果，實驗結果和理論分析相一致。

( 2 ) based on the wave equation in the acoustic fluid space and the theory of thin - wall structure, the non - symmetrical coupled structure - acoustic dynamic equation without damping is studied. the non - symmetric system of the finite element model for coupled structure - acoustic response is solved by the conjugate subspace iteration method

由聲空間波動方程和薄板理論出發，對聲場?結構耦合系統的模態分析提出了有限元數值方法，採用共扼子空間迭代法對非對稱特徵方程進行處理，採用靜凝聚法消除質量矩陣的奇異性。

In this paper, according to the equation of voltage vector of single - phase motor operating at symmetrical condition, author presents a new voltage - vector pwm method of variable frequency control for single - phase motor. in system, the voltage vector is used as a control parameter

本文根據單相電動機對稱運行時的合成電壓矢量方程，提出了以合成電壓矢量為控制量的單相電動機電壓矢量式pwm變頻調速控制方法，並進行了計算機模擬及製作了單相變頻器。

Through the simulation, we prove that adaptive control can improve the dynamic characteristic of the asymmetrical cylinder velocity system which controlled by symmetrical valve. it also can make the system ’ s dynamic characteristic to be same in different directions, and the system ’ s big over shoot and stabilization time has been reduced, the stability of the system has been

通過模擬分析，證明了自適應控制能夠有效地改善對稱閥控制非對稱缸速度系統的動態性能，使正反兩個方向上的動態特性對稱，保證系統的穩定性，降低了系統的超調量和穩定時間。

On the base of researching in several application security systems, this paper did much work on researching in symmetrical cryptographic system, public key cryptographic system, digital signature system and the digital certificate application technology in the contemporary cryptography, and issued a suitable security application framework taking account of the characteristics of the rfmdms, several key technologies in constructing were discussed also

本文在對國內外各種安全應用系統調查研究的基礎上，圍繞現代密碼學中對稱式密碼系統、公開密鑰密碼系統、數字簽名系統、數字證書應用技術等進行了深入研究，並結合rfmdms體系結構方面的特點，提出了適合rfmdms的安全應用系統框架，而且對系統實現中的關鍵技術進行了研究。

Combining the methods of in - phase variable - frequency adjusting speed with brushless dc control, this system makes full use of characteristic of high static precision and dynamic fast response. in the synchronous model, based on the idea of symmetrical svpwm pattern generator using cpld device implementation

本文首先探討了同步電動機調速系統的控制理論，針對本轉速源的設計要求，作者提出了他控式變頻調速與自控式無刷直流調速相結合的調速方案。

Hose fittings with clamp units - symmetrical half coupling guillemin system

帶夾件的軟管配件.對稱聯軸節

A hybrid simulation method for symmetrical system is presented, combining the hybrid simulation method with the proposed equivalent simulation model, a hybrid simulation method for hvdc - vsc is presented, which is useful for studying the action and reaction between the ac and dc systems

提出了一種在系統對稱的條件下實現混合模擬的方法，把混合模擬的方法與hvdc vsc的等效模擬模型相結合，提出了hvdc vsc混合模擬方案，為研究hvdc vsc與交流系統之間的相互作用奠定了基礎。