查询词典 difference frequency

This paper introduces the development of the 2cm phase standard which uses phase-held frequency convention and synchronical phase-lock bichannel phase compari- son system.The standard features wide frequency range,wide dynamic range,high accura- cy,multi-function,and convenient operation.It was qualified by self-calibration method.

本文介绍了两厘米相位标准的研制情况，该装置采用变频保相、同步锁相的双通道比相系统，具有频率范围宽，动态范围大，准确度高，操作方便，多功能等特点，利用自校准法对装置进行了测试检定。

This paper describes a piezoelectric drive circuit which can find the syntonic frequency of motor through scanning frequency region based on computer controlling.

提出了一种基于计算机控制的压电超声马达谐振频率自动搜寻系统。

Research shows turning round vibration is the main vibration shape of system of direct empty cold construction, should consider fan of; of vibration shape coupling many a little bit the structural vibration that syntonic drive causes is answered lesser, movement of fan low frequency is more than the influence of high frequency movement to the structure to structural influence.

探究表明扭转振动是直接空冷结构体系的主要振型，应该考虑振型耦合；风机多点谐振激励引起的结构振动响应较小，风机低频运转对结构的影响大于高频运转对结构的影响。

The method is as follows, at first, to calculate the frequency response function of structure corresponding every blasting syntony ponderance, then to calculate the response of structure under this syntony ponderance by using frequency response function, at last, the response of the whole system can be worked out by superposition.

计算方法是先计算每一爆破谐分量对应于结构的频响函数，然后用频响函数计算出结构在此谐分量下的响应，最后用叠加法得到整个系统的响应。

We figure out the telescope mount parameters by observing stars with CCD, and establish a measurement system, including CCD and image acquisition card to collect stars'image data, time and frequency system (made up of high accuracy counter, the GPS second signal and 10MHz frequency standard), the observing software in VC++6.0 for collecting and processing star image and the image processing software programmed with MATLAB.

建立了一套用于测定望远镜机架指向误差模型参数的系统，包括：CCD 及图像卡等硬件系统用于采集恒星图像数据；使用高精度的计数器、GPS 提供的秒信号和标准10MHz信号开发了用于观测软件的时间频率系统；使用VC++6.0 编制了包括用于计算恒星位置及图像采集和处理的观测程序，并用MATLAB编制了用于处理观测数据的程序。

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。

Log-domain companding technique takes advantage of the exponential I/V characteristics of the active devices such as bipolar junction transistors, compressing the dynamic range of the input sigal and reducing internal voltage amplitudes, it can maintain large dynamic range and high operating frequency under low supply voltage , the main area of application for this technique is the implementation of continuous-time fully integrated filters with low voltage, wide dynamic range, high-frequency, and wide tenability.

对数域压扩技术利用BJT晶体管等有源器件的指数Ⅰ-Ⅴ特性，对信号作对数压缩处理，大大降低了电路内部节点电压的摆幅，能在低电源电压下保持大信号动态范围和高工作频率，该技术的主要应用是设计具有低电压、宽调谐范围、高工作频率和宽动态范围特性的连续时间全集成滤波器——对数域滤波器。

Objective To probe into the effects of military noise on the hearing threshold of the speech frequency and high frequency in the elders.

目的 探讨军事噪声对老年人言语频率及高频听力的影响。

Feature evaluating function based document frequency with minimum term frequency threshold is present in the paper.

2针对文本关联分析中难以确定最小支持度阈值的问题，提出N个最频繁项集挖掘算法。

In noise-exposed ears, the occurrence of threshold changes in the high frequency range (10 to 20 kHz) is earlier than that in the low frequency range (0.5 to 6 kHz).

接触噪声的各年龄组10～18 kHz阈值随年龄的增长而升高；不同工龄组比较，6～10年工龄组的10～18 kHz阈值明显升高；不同噪声强度组的10～20 kHz阈值比较差异无显著性（P＞0.05）。

"The operators will suffer a temporary decrease in the number of consumers and short message services as people may not like having to provide their ID cards for a phone number," Xu Junqi, vice-dean with the Policy-Making Institute of the Telecommunications Research Centre under MII, said yesterday.

信息产业部下属的通信决策研究院副主任徐俊其昨天说：&实行手机实名制后，人们可能不太情愿用身份证注册手机号，所以通信运营商会暂时面临用户减少和短信用户减少的问题。&

I don't believe in make-believe!

我不相信这些虚构的故事。