工频

As to the asymmetry phenomenon of current duplex communication terminal of wireless communication systems in the short-range open segment,intelligent RF transceiver dual-use hardware terminal system is designed.

针对目前短程开放段无线通信系统双工通信终端不对称现象，设计智能化无线射频收发两用硬件终端系统。

According to the definition of the OMOPM family, we only need appropriate parameters and proper sets of orthogonal basis function.

根据此一家族的定义内容，只需要适当的指定调变参数以及选择适当的正交基底函数集合，便可以囊括了新的调变形式以及传统的调变形式，正交分频多工调变技术也是其中的一个特例。

In order to design lighter and faster hydraulic excavator, a rigid-flexible hybrid modeling method based on rigid multi-body dynamics and finite element method was put forward to study the dynamic characteristic of hydraulic excavator in its whole working cycle. The working equipment with characteristic of time-varying structure was taken as research object, and radial acceleration was computed as tags of key load.

为适应液压挖掘机高速、轻量化的要求，以具有时变固频特性的液压挖掘机工作装置为研究对象，提出了以角加速度判断时变结构的关键工况，利用刚性多体动力学和有限元方法对液压挖掘机在整个作业循环中的动力学特性进行建模和分析。

Numerical Simulation and Experimental Investigation on A Thermoacoustic Engine with Tapered Resonance Tube A symmetrical standing-wave thermoacoustic engine with tapered resonance tube has been numerically simulated with liner thermoacoustics. The simulation shows that using tapered resonance tube in thermoacoustic engine could decrease the velocity amplitude and lower the total acoustic power loss in the resonance tube. The experimental results indicate that the harmonic was suppressed effectively by using the tapered resonance tube, and the pressure ratio was improved.

采用锥形谐振管的热声发动机的数值模拟和实验研究利用线性热声理论，对一台采用锥形谐振管的驻波型热声发动机进行了数值模拟，发现采用锥形谐振管可有效降低工质气体的速度振幅，进而减小在谐振管中声功率的损失；与一台在相同频率下工作的采用等直径圆柱谐振管的驻波型热声发动机进行了实验对比，结果表明，在使用锥形管作为谐振管的热声发动机系统中，谐振管中的非线性效应得到了明显的抑制，热声发动机在基频模式下稳定运行，压比增大而加热温度降低。

The phase of ω0 frequency fluctuates tempestuously. The resonance peaks of flexural and torsional vibrations response are present at 2/3ω0 1/2ω0 1/3ω0 and 1/4ω0 with three kinds cracked rotor models. Near 1/2ω0 frequency, quasi-periodic and chaotic motions maybe appear. Periodic, quasi-periodic and chaotic motions show on alternately when the rotating speed is near to 2/3ω0.Combined step-by-step integral method with traditional transfer matrix method, an increment transfer matrix method is put forward.

研究结果表明：各种故障情况下，华北电力大学博士学位论文弯振和扭振之间都存在祸合关系，但弯扭祸合振动一般不会威胁机组安全运行：在叶片丢失或滑环飞脱故障时，将产生很大的弯振，同时各转子扭振也将被激发出来，它以工倍频和前三阶固有频率为主；在各种电气故障情况下，各转子都很快被激励出较大幅值的扭振来，相应各转子弯振也发生一定的变化，但它的变化明显滞后于扭振，扭振和扭矩主要以前三阶固有频率为主。

In our study, we also observed the different influence between TTB-USA and RFCA on blood coagulable states (by examining the change ofα-granule membrane protein、Tissue type plasminogen activatior、Plasmingen activator inhibitor-1)、 endothelium function (by examining the change of endothelin、nitric oxide) and myocardial injury (by examining the change of creatine kinase、MB isoenzy of creatine kinase and cardiac troponin T).

为观察超声消融与射频消融对血凝状态、内皮功能及心肌损伤的影响，进一步对超声消融的安全性进行评价，我们在插管前、插管后、消融后即刻、消融后30min及48小时5次抽静脉血，分别测定血小板α-颗粒糖蛋白(GMP-140)阳性表达活化血小板百分率、内皮素、一氧化氮、组织型纤溶酶原激活剂及纤溶酶原激活剂抑制物-1(PAI-1)的变化；于消融前、消融后即刻、2hr、8hr、24hr、48hr、72hr抽取静脉血，检测肌酸激酶、肌酸激酶MB同工酶及心肌肌钙蛋白T的变化。

Both kinds of algorithms can improve the static and dynamitic characteristics of the system, and meet the design requirements.

在进行系统整体设计和软、硬件设计时，本文充分考虑了系统的实际工况，设置了手柄信号中位死区，以消除系统的误动作；同时，为适应比例阀的工作频率，利用单片机对PWM输出信号进行了分频处理，保证了通过比例阀的平均电流值不变。

For example, IEEE 802.16e supports vehicle speed up to 120 km/hour, and IEEE 802.20 supports vehicle speed up to 250 km/hour. OFDM systems can be used efficiently in time invariant environments with one-tap equalizers. However, subcarriers are no longer orthogonal to each other in time-varying channels, and this causes the intercarrier interference and degrades the system performance.

传统的正交分频多工系统可以有效率地使用在非时变通道中，且仅需简单的等化器，即可修正通道效应，但在移动的环境中，通道随著时间改变，使得接收端的子载波失去正交性，因而导致子载波之间的相互干扰，使得解调变后的效能降低。

For example, IEEE 802.16-2005 supports vehicle speed up to 120 km/hour. OFDM systems can be used efficiently in time invariant environments with one-tap equalizers. However, subcarriers are no longer orthogonal to each other in time-varying channels, and this causes the intercarrier interference and degrades the system performance.

传统的正交分频多工系统可以有效率地使用在非时变通道中，且仅需简单的等化器，即可修正通道效应，但在移动的环境中，通道随著时间改变，使得接收端的子载波失去正交性，因而导致子载波之间的相互干扰，使得解调变后的效能降低。

However, OFDM systems can be extremely sensitive to synchronization errors. Minor carrier frequency offset and symbol time offset can cause intersymbol and intercarrier interference and degrade system performance very seriously.

然而，正交分频多工对於对同步错误极为敏感，些许的载波频率偏移与符元时序偏移就能造成符际干扰及子载波干扰，导致系统效能变差。

However, as the name（read－only memory）implies, CD disks cannot be written onorchanged in any way.

然而，正如其名字所指出的那样，CD盘不能写，也不能用任何方式改变其内容。

Galvanizes steel pallet is mainly export which suits standard packing of European Union, the North America. galvanizes steel pallet is suitable to heavy rack. Pallet surface can design plate type, corrugated and the gap form, satisfies the different requirements.

镀锌钢托盘多用于出口，替代木托盘，免薰蒸，符合欧盟、北美各国对出口货物包装材料的法令要求；喷涂钢托盘适用于重载上货架之用，托盘表面根据需要制作成平板状、波纹状及间隔形式，满足不同的使用要求。