查询词典 D.A.

So digitalizing analog signal is the trend of information technology, in which A/D and D/A plays an important role.

所以模拟信号数字化是信息技术的发展趋势，而A／D和D／A转换器在其中扮演着重要角色。

"The best indicator of a person's vitamin D status is the blood level of a vitamin D compound called 25-hydroxyvitamin D ," said Babette Zemel, Ph.D., a nutritional anthropologist at Children's Hospital and primary investigator of this study.

"的最佳指标，一个人的维生素d地位，是血服用维生素d化合物称为25 -羟丁说：" babette泽梅尔博士，营养人类学家儿童医院和基层调查这学习。

And this causes a frequency change Δf. The resonant point tracing algorithm describes how to detect Δf. So it can introduce a feedback frequencydifference -Δf through a closed loop to realize the resonant state o In the digitaldetection scenario, using staircase wave to replace saw tooth wave, it can overcome a lot of shortcomings in the analog system. The character of the staircase wave affects the detection precision directly. This thesis analyzes a high precision scenario producing a staircase waveform in detail. It can reduce the number of the bits in D/A converter greatly. This thesis proposes another method to improve the detection precision in case that the A/D converter has comparatively little number of bits, while this method will not increase the cost of the system greatly.

在谐振式光纤陀螺中，环形谐振腔的旋转使得谐振腔的谐振频率发生了变化，从而产生了一个与旋转速度成正比的频率变化值△f，谐振点跟踪算法描述了如何检测出△f，从而可以通过闭环在系统中引入反馈频差-△f，实现光路的谐振状态；在数字闭环检测方案中，用阶梯波作为反馈信号来代替锯齿波，可以克服原来模拟系统中锯齿波的很多缺点，阶梯波的性能直接影响着系统的测量精度，本论文详细分析了一种高精度阶梯波生成方案，使得所需D／A的位数大大降低；本文还分析了A／D转换器对系统测量精度的影响，提出了一种A／D转换器位数较少的情况下提高系统测量精度的措施，同时又不会增加太多的系统成本。

The peripheral circuit of A/D, D/A, including the interface circuit and the anti-interference to the hardware is extended on the basis of ARM developed board.

在ARM开发板的基础上对A／D、D／A等外围电路进行了扩展，设计了信号放大、分压等接口电路，并加入相应的硬件抗干扰措施。

According to the auto brake tester, it has been designed that the hardware circuit of the testing system based on 89C55 single-chip microcomputer, including A/D circuits for sensor interfaces, D/A circuits for needle indicating type display device, driving circuits for brake motors, the communication interface circuitbetween the single-chip microcomputer and pc, etc.

针对所研究的汽车制动试验台，设计了基于89C55单片机的试验台测控系统硬件电路，包括传感器接口与A／D转换电路、指针式显示装置的D／A转换电路、制动电机驱动电路、单片机与PC机之间通讯的接口电路等。

The working pattern of discrete-time system is flexible, but it need A/D and D/A, which make that system work slowly.

离散时间系统有采用的方式灵活等特点，但由于离散时间系统需要A／D、D／A转换，处理信号的速度慢等缺点。

But there was no current modulate circuit for TDLAS system.The design of modulation circuit for tunable diode laser based on DDS has been introduced.The main idea of design is using MCU to control DDS and D/A chips,so we can get sine wave and saw tooth signals.

DDS器件采用高速数字电路和高速D/A转换技术，具备了频率转换时间短、频率分辨率高、频率稳定度高、输出信号频率和相位可快速程控切换等优点，可以实现对信号的全数字式调制。

Using coder ,D/A transducer and frequency converting speed regulator makes up the automatic control system of rope machine's wire ranging apparatus.

利用编码器、D/A变换器、变频调速装置，构成制绳机排线自动控制系统，将原间歇位移随动控制系统改为连续位移自动控制系统，可以解决制绳机钢丝绳收线排布不均的问

At the same time, the paper includes traits of embedded operating system μC/OS- II and the method of transplanting in the detail, and how to transplant the embedded TCP/IP protocol, in the foundation, I design a data collection system,which is made up of CGItechnic、51SCM、pint-size TCP/IP protocol、 Ethernet interface chip、A/D, D/A switch equipment.

同时本文详细介绍了嵌入式操作系统μC／OS-Ⅱ的结构特点和如何移植到处理器中，以及如何将嵌入式TCP／IP协议栈μIP移植其中，在此基础上在通过CGI技术构成了一个数据采集交互系统，系统通过51系统单片机、精简的TCP／IP协议栈、以太网接口芯片、A／D、D／A转换器等接口电路实现了系统的核心结构。

The photovoltaic effect of the new D-A compounds on GaAs electrode in electrochemical photovoltaic cell were measured.

在光电化学电池中，在GaAs电极上测量了这4种D-A化合物的光伏效应。

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。