参考周期

Access to a large number of Chinese and foreign literatures, this text summarized the life cycle of aphids including anholocyclic type, heteroecious holocyclic type and antoecious holocyclic type, and the important biological characteristics including alternation of generations, difference of hibernation and polymorphism, it offered the theory basic of comprehensive prevention and control.

通过查阅大量的中外文献，对蚜虫生活周期的不全周期生活史、全周期同寄主生活史和全周期异寄主生活史进行了阐述，归纳出蚜虫生活周期中的世代交替、越冬方式的差异、多型现象几个主要生物学特点，为蚜虫的科学控制提供一定的参考价值。

According to the demand of high magnetic field power supply, reference is increased with a set ramp rate and stops at a set stable value, so reference system is composed of digital setting and digit to analog converting circuit. But the stability of reference is mostly guaranteed by the performance of D/A circuit, so D/A circuit is particularly studied in reference system. The scheme of D/A circuit, the selection of DAC and its voltage reference, hardware anti-jamming design and PCB design are discussed in detail, and software of remote control and PLC are discussed in brief. Zero-flux DC current transformer well satisfies the demands of the high stability of Load current detection unit, so the principle of zero-flux DC current transformer is analyzed; in the mean time a project which detects the long term stability is designed. During 8 hours, analog signal which is detected with high precision digit multimeter is recorded in computer at 1HZ frequency by GPIB communication. The drift error source and related parameters are explained in the compare-amplify part. Detailed subtraction circuit is designed; also amplifier chip and periphery components are selected and verified according to the theory of error analysis.

根据强磁场电源的需求，参考源应按照软件设定的斜率逐渐上升到设定稳态值，则参考源系统应由数字给定和数模转换电路两大部分组成，而参考源的稳定度主要依靠完成数模转换功能的模拟电路的性能来保证，因此本文对参考源系统的研究以数模转换电路为重点，分别从电路方案的确定、数模转换芯片及其基准电压源的选取和验证、电路板硬件抗干扰和PCB设计几方面进行了论述，然后对数字给定部分的远控组态和PLC程序设计作了简要介绍；采用零磁通原理的直流电流转换器很好地满足了对负载电流检测单元高稳定度的需求，本文详细分析了零磁通检测的原理，并在选定此种类型电流转换器的基础上设计了一套检测长期稳定度的方案，8小时内以1秒为采样周期，通过计算机Labview程序和高精度数字电压表的GPIB通讯，将被高精度数字电压表数字化后的模拟信号采样值连续记录至计算机中；比较放大环节简要阐述了漂移产生的原因和相关参数指标，确定了具体的减法电路形式，并根据误差分析理论对运算放大器和外围元器件进行了选取和验证。

Based on VHZ data recorded by 7 stations of China digital seismograph network for Nov. 14, 2001, earthquake in the west of the Kunlun mountain pass, we extracted spherical mode of 0S4-0S76 of the earth free oscillation using power spectral density estimation. Because the frequency response of seismograph in China digital seismograph network suppress information of solid tide, we do not need to remove the solid tide in our procession.

利用中国数字地震台网改造后的7个台站的VHZ波形资料，采用功率谱密度估计方法，利用中国数字地震台网地震仪对低频信号压制的特点，在没有对资料去除固体潮影响的情况下，提取了2001年11月14日昆仑山口西地震激发的0S4-0S76地球球型自由振荡，并与地球初步参考模型的理论自由振荡周期进行对比，结果表明与PREM预测的球型自由振荡周期符合得很好。

In this dissertation, digital lock-in detection techniques under integer period sampling and non-integer period sampling are separately investigated (1) Under integer period sampling, digital signal sequence is acquired through sampling the measured signal, but digital reference sequence is acquired through mathematical operation, then digital lock-in detection can be realized by calculating crosscorrelation function of digital signal sequence and digital reference sequence Harmonic measure is also analyzed, and a method of measuring harmonic of a periodic signal under aliasing is put forward.

本文对使用采样ADC把模拟信号转换为数字信号并通过计算数字信号的相关函数来实现锁定检测的技术进行了研究，在此基础上设计了一个多功能的数字LIA并在一些科学实验中进行了应用。本文对整周期采样和非整周期采样时的数字锁定检测技术分别进行了研究。(1)在整周期采样时，对被测信号进行采样得到信号序列，而参考序列由数学运算得到，通过计算信号序列和参考序列的互相关函数就可实现锁定检测。

The instrument simultaneously sample for three phase voltage and current. Rotary photoelectric coding switch and LCD are used for human-computer interaction. it makes the interface compact and efficient. Utilizing the function of positive and negative edge trigger of the programmable counter array unit in MPU, signal zero-cross is captured for the phase detected based on double way. The software synchronism sampling method based on real-time parameter self-optimizing minishes period truncation error, and the measurement accuracy is improved. The digitization power measure imports traditional two-unit and three-unit methods and expands application range of the instrument. The capacity is discriminated by soft ware table-look-up on the load loss. The value of a quantity is converted to the value when reference temperature (75 ℃) from test temperature.

该仪器具有以下特点：仪器对三相电压电流同时采样；基于旋转式光电编码器和液晶显示屏的人机交互界面简洁而高效；可编程计数器阵列PCA"捕获"信号的过零点用于双向过零平均鉴相，得到准确的相位差和周期；基于实时参数自寻优的软件同步采样，有效地减小了周期截断误差，提高了测量准确度；数字化功率测量引入了传统的二表法和三表法，扩展了仪器的使用范围；实际容量根据负载损耗用软件查表的方法来判别；测量值已从试验温度折算到了参考温度(75℃)时的值。

In order to measure motion characteristic and dynamic parameters of MEMS resonator in every moment based on the technique of stroboscopic imaging, clear motion images in one cycle were obtained.

为测量MEMS 谐振器周期运动过程中各个时刻的运动特性及其动态特性参数，基于频闪成像原理得到了MEMS 谐振器一个周期内各时刻的清晰运动图像，利用块匹配技术对MEMS 谐振器的运动图像进行处理，从而得到其特性参数，为MEMS器件的设计提供重要参考。

On the basis of state space model of system dynamics, the decomposition of periodic term and trend term in the time series of both power demand and Gross Domestic Product are carried out respectively, and it is discovered that there is a strong correlativity between the periodic term...

文章基于系统动力学的状态空间模型对电力需求与国内生产总值(GrossDomesticProduct，GDP)增长率时间序列分别进行周期项与趋势项的分解，发现电力需求与GDP分解的周期项之间存在很强的相关关系；基于此关系及电力需求增长率序列数据自身的变化规律，采用计量经济模型预测了2004~2008年我国电力需求增长率，以期为当前的电力规划工作提供参考数据。

Because the additional reference signal is not necessary, the delayed time is not related to the period of UPO and should not be the integral multiple of the period of UPO, so the presented method is simple and easy to apply.

由于不需要外加参考信号，延迟时间与UPO的周期无关，不必是UPO周期的整数倍，所以该方法简单易行。转载于中国论文联盟 http：//www.lwlm.com

In this s cheme, when model integration proceeds to the period of analogue updating, multiple reference states are reselected and optimal forecast vectors are est i mated from multiforecasts produced by the analoguedynamical model using the hy perplane approximation method. Such a "selectionestimation" procedure is peri od ically repeated until the entire forecast is completed.

这一方法通过引入相似更新周期的新概念，在预报进行到相似更新周期时重新选取多个参考态，并采用超平面近似法将相似动力模式产生的多个预报估计成最佳预报向量，这样的&选取-估计&过程循环往复，从而完成整个时段的预报。

Because the additional reference signal is not necessary, the delayed time is not related to the period of UPO and should not be the integral multiple of the period of UPO, so the presented method is simple and easy to apply.

由于不需要外加参考信号，延迟时间与UPO的周期无关，不必是UPO周期的整数倍，所以该方法简单易行。中国诺宇综合网http：//www.siaaa.com

In the negative and interrogative forms, of course, this is identical to the non-emphatic forms.

。但是，在否定句或疑问句里，这种带有"do"的方法表达的效果却没有什么强调的意思。

Go down on one's knees;kneel down

屈膝跪下。。。下跪祈祷