Hoffman and scientists from the british antarctic survey , who reported their findings in the science journal nature on wednesday , discovered the unusual mating patterns while studying a colony of the seals on the island of south georgia 霍夫曼博士和来自英国南极考察队的科学家在研究南乔治亚岛的海豹群时发现了海狗这一不寻常的择偶现象。
Hoffman and scientists from the british antarctic survey ( bas ) , who reported their findings in the science journal nature on wednesday , discovered the unusual mating patterns while studying a colony of the seals on the island of south georgia 霍夫曼博士和来自英国南极考察队的科学家在研究南乔治亚岛的海豹群时发现了海狗这一不寻常的择偶现象。
The main purpose of this paper is to treat a gravity wave field with an array of two or more cylinders and to demonstrate the wave height distribution with different flow speed or different flow incident angle in a wave - current flow field with constant depth 摘要本文的主要目的，在研究重?水波通过有限水深之群柱间时周围?场的波高现象，以及探讨波?共存时在?同?速及?同入射角?经圆柱群时所造成之波高变化。
Not only is crucial information more readily available to those who aren ' t avid readers , but sometimes those who take in a video might be among the best informed on important subjects , says elizabeth thoman , founder of the center for media literacy in los angeles 洛杉矶媒体识读中心的创办人伊莉莎白?托曼表示，不但对不习于阅读的族群来说，重要的资讯更容易取得，就连教育程度最高的族群时也藉录影带才得知重要的议题。
The definition and measurement techniques for group delay has been described and analysed in this paper , the new techniques , being called dine - mixer technique and vector - mixer calibration for measuring the absolute group delay of the frequency converters has been researched and analysed in detail also in this paper 摘要描述和分析群时延的含义和测量方法，着重研究了变频链路绝对群时延的测量方法，对三混频器和矢量混频器技术进行了详细分析和论述。
The dissertation presents the combined theoretical , numerical and experimental studies on the experimental modeling of the actuator , the design of test rig and control system , the modeling of two - dimensional airfoil aeroelastic system , the control design of active flutter suppression , and the effect of group delay in the digital filter on the stability of aeroelastic closed - loop system 本文通过理论分析、数值仿真与风洞实验相结合的方法,研究了超声电机作动器建模、翼段颤振实验装置和控制系统设计、二维翼段气动弹性系统建模、颤振抑制控制律设计以及数字滤波器群时延对颤振抑制闭环系统稳定性影响等问题。
The results of the test demonstrated that the system has a good performance in the linearity , dynamic scope , isolation , coherence of the amplitude . the group delay of the upmixers is 2ns , which is better than other domestic manufactures . because the inconsistency between the isolation and the phase coherence , and the error of the test method , we haven ’ t gotten the good performance of the phase coherence . the next work is improving the restrain of the filter to the lo signal and the phase test methods 在单路发射通道上,群时延达到了2ns ,优于国内很多产品。三路通道之间的相位一致性由于测试方法的误差以及隔离度指标的牵引作用,我们不能调试达到非常好的在相位一致性指标,再下一轮的工作中必须提高滤波器对本振信号的抑制度,改进相位测试方法以达到指标要求。
In the fifth chapter , a new fully differential operational amplifier with voltage and current - mode negative feedback has been proposed , which can stabilize its quiescent operation point , using the characteristic of mos transistors which operate in the triode region acting as active variable resistor , a fully differential fourth - order chebyshev low - pass filter with tunable frequency and bessel low - pass filter with accurate group delay based on r - mosfet - c and operational amplifier has been designed 第五章：提出了一种新的既具有电压共模负反馈又同时具有电流共模负反馈的全差分运算放大器电路，能较好地稳定电路的静态工作点，并应用mos管工作在线性区可作有源可变电阻用的特性设计得到了截止频率可连续调节的高性能r - mosfet - c 、运放结构切比雪夫( chebyshev )和精确群时延值贝塞尔( bessel )低通滤波器。
In the seventh chapter , some of the above proposed new circuit , such as high frequency , high definition 12 - bit , 80mhz samples / s current - steering dac and fully differential r - mosfet - c bessel filter with accurate group delay , high accuracy bandgap reference and high drive capability cmos operational amplifier have been applied in communication gsm baseband i / o port integrated circuit , all the above blocks meet well with the design requirements of the system , and gain the better testing results , in the mean time , the above proposed high accuracy bandgap reference circuit als 第七章:将本文第二章提出的高速、高精度12位、 80mhz采样率电流舵结构的数模转换器和第五章提出的r一mosfet一c结构且具有精确群时延值的贝塞尔( bessel )滤波器以及第六章提出的高精度带隙基准电压源和高驱动能力全差分运算放大器电路应用于通信gsm基带输入/输出端口芯片，满足系统设计要求并取得了令人满意的实测结果。
In this paper , difficulties such as the design of hts microwave passive component , the lithography technology , encapsulation and testing at low temperature etc . are solved . a hts delayline with center frequency at 4ghz , bandwidth of 4ghz is manufactured and tested . it ’ s group delay is larger than 10 ns 本文在解决高温超导微波无源器件的设计、光刻工艺、密封封装和低温测量等难点的同时,对一个f _ 0 (中心频率)为4ghz ,带宽4ghz的高温超导延迟线进行加工、封装、测量,群时延大于10ns 。
