查询词典 D.A.

Furthermore, a high precision demodulation scheme by D/A converter is also proposed.

为了提高系统性能，论文还提出了一种高精度的基于D/A输出控制F-P滤波器的解调方案。

a kind of design project of multifunction electric power quality gauged instrument based on virtual instrument is put forward in this article.this system integrates virtual instrument programming and power electronics together,to realize diverse signals of current electric power quality field allin one.the integrated signal generator unit which carries out the collection of high speed digital data,d/ a conversion and analog output in four channels,unsymmetrical synchro control fifo etc.by fpga are introduced,the flow of electric power system various signal which generates by vc programming is elaborated,and the structural design of signal amplification unit is analysed.the experiment text result shows that this gauged instrument has attained current advanced high grade of accuracy and it will accelerate the steps of electric power quality calibration because of its accuracy and versatility.

摘 要：提出一种基于虚拟仪器技术的多功能电能质量标定仪的设计方案，采用虚拟仪器编程技术和电力电子技术相结合实现集目前电能质量领域的多样信号于一体。介绍采用fpga实现高速数字量采集、d/a转换及4通道模拟量输出、非对称同步控制fifo等的集成信号发生单元，阐述利用vc编程实现的电力系统多样信号的产生流程，分析信号放大单元的结构设计。实验测试结果表明该标定仪达到目前先进的高精度等级，由于其准确性和多功能性将加快电能质量标定的步伐。

The results show that the phase error of the vector measurement is zero, and amplitude error can be eliminated, and the error caused by D/A is much lower than a LBS.

结果证明，相位测量的理论误差为零，幅度测量的理论误差可用修正系数消除，且D/A有限字长引起的误差远小于一个LBS。

In these chromophores, the ring-locked triene employed as a conjugation bridge and the thiobarbituric acid moiety was as an electron acceptor in a D-π-A units.

在这些发色团中，环锁定的三烯和9，10-二氢蒽用作共轭桥，巴比妥酸和甲氧其分别作为吸电子和给电子基，组成非共轭的两个D-π-A单位。

A direct digital synthesis technology, based on large capacity synchronous dynamic random access memory, was used, in which the table of arbitrary waveform amplitude generated by CPU according to testing requirement was stored, and FPGA outputs the amplitudes to D/A converter.

采用基于大容量同步动态随机存储器任意波形表的直接数字合成技术，由CPU根据检测需求生成任意波形幅值表，存储到SDRAM中，现场可编程门阵列器件将波形数据输出到D/A转换器，经滤波、放大后驱动涡流探头。

The molecule has a typical D-π-A structure with terminal units of electron donor and accepter groups. The triphenylamine group, as the electron donor, is connected to the oxadiazole group which is the electron accepter through the cinnamene group.

该分子具有典型的D-π-A型推拉电子结构，三苯胺基团作为给电子基通过苯乙烯共轭链桥接到吸电子基1，3，4-恶二唑基团。

The latest results about research on dye-sensitized solar cells are reviewed.So far,most of the organic dyes applied in DSSCs belong to typical D-π-A structures with both electron donorand electron acceptorlinked by aπ-conjugation bridge.According to this structure,the novel conjugated organic dyes that have N,N-dimethylanilinemoieties as the electron donor and a cyanoacetic acidmoiety as the electron acceptor were synthesized for DSSCs.

在第四章中首先概述了染料敏化太阳能电池的最新研究进展，并对其的结构和工作基本原理进行介绍，目前，有机染料分子大部分都是D-π-A结构，我们按照这样的结构设计和合成出六种新型米氏酮-氰基类有机染料分子，该类染料是由米氏酮衍生而来的，合成步骤短，工艺简单。

Thereinto, the analog receiver, the main body of the UATS preprocessor, conditions the output signals of the receiving transducer, which are amplified and filtered.And the driving circuit implements the low-pass filtering of the D/A converters output signals and offers the result to the power amplifier circuit as its input.In addition, the fathoming circuit acquires the depth information of the underwater electronic equipment cabin to ensure a relatively convenient way to adjust and recover the underwater parts of the system.

其中，模拟接收机完成对接收换能器输出信号的放大、滤波等调理工作，是水声靶标系统预处理机的主体部分；驱动电路实现对D/A转换器输出信号的低通滤波，用以产生功率放大电路的输入信号；测深电路用来获取水下电子舱的深度信息，便于系统水下部分的调整和回收。

A number of GPIB data acquisition products appeared throughout the 1970s and early 1980s, including voltmeters, digitizers, multiplexers, switches, digital I/O, D/A converters, and simple arbitrary waveform generators.

一定数量的GPIB 数据采集产品出现在70 年代和80 年代初期过程中，包括电压表，数字化器，多重通道，开关，数字式I/O， D/A 交换器，并且简单的任意信号波形发电器。

The working principle of DDS is introduced,and memory design techniques based on quarter-wave is adopted for enhancing system resolution and reducing the resource utilization of FPGA.The DAC0832chip is used as a D/A converter.This system design has passed the verification.

介绍DDS的工作原理，采用基于1/4波形的存储器设计技术可提高系统的分辨率和降低FPGA资源的利用率，采用DAC0832作为D/A转换器。

This one mode pays close attention to network credence foundation of the businessman very much.

这一模式非常关注商人的网络信用基础。

Cell morphology of bacterial ghost of Pasteurella multocida was observed by scanning electron microscopy and inactivation ratio was estimated by CFU analysi.

扫描电镜观察多杀性巴氏杆菌细菌幽灵和菌落形成单位评价遗传灭活率。