和电路

In the equivalent transformation of the circuit, it can just treat the negative resistance as the positive resistance and use the Ohm theory.

讨论了用Multisim实现负电阻的仿真和分析的方法，得出负电阻和负电阻的串并联连接以及负电阻和正电阻的串并联连接电路中，负电阻的处理方法与正电阻一致的结论。

The results of numerical calculation conform the exactness and validity of theoretical analysis and circuit design.

结合理论分析和实验结果，用数值方法进行了对照分析，进一步验证理论分析和实验电路设计的正确性和有效性。

First of all, we talk about embedded systems and digital radios basic concepts and features. Secondly, the system described in detail the overall function and functions of various modules. On the third, described in detail the hardware system design, and mainly focused on the core hardware system board and the expansion of all parts of circuit board design. Fourth, described in detail the Custom embedded WinCE operating systems, their main task is to reduce, modify Bootloader.

首先，介绍嵌入式系统的基本概念和特点以及本文所论述的结构；其次，详细介绍了系统的硬件的总体设计以及软件的总体设计；第三，详细介绍了系统的各个硬件模块的设计，主要是对硬件系统的核心板和扩展板的各部分电路的设计进行了介绍；第四，详细介绍了嵌入式WinCE操作系统的定制方法，主要工作是对其进行裁减，编写Bootloader；并通过中断和流接口开发基于嵌入式系统的驱动程序，通过修改编写驱动程序让嵌入式系统能够满足当前的项目的需要，实现最小化同时又是最完全的系统；第五，详细介绍了服务器端，嵌入式控制端，采集端3大部分的软件以及自己定制的通讯协议。

In recent years, systems which based on fractional differential and integral fractional, have been researched extensively, involving fractional circuit, fractional digital signal processing, fractional dynamics control systems and fractional-Chaos and super-chaos, Chaos Control and fractional chaos synchronization, and security communications. And a lot of theoretical and practical results are obtained.

故而近年来基于分数阶微分和积分的分数阶系统已在动力学系统中得以较为广泛的研究，其中涉及分数阶电路、分数阶数字信号处理、分数阶动力学控制系统以及分数阶混沌和超混沌、分数阶混沌控制与混沌同步、保密通信等多个领域，取得了不少的理论和实际结果。

As an example, in the design of a 4-bit ripple carry adder, the second and fourth full adders do not use output inverters for carry generation. one inverter delay is eliminated for every two full adders in the adder chain, and four transistors are reduced. Similarly, in complex designs like the multiplier, the output inverters for generating sum and carry can be used in alternative stages, thereby improving speed and reducing area.

例如，在4位行波进位加法器中，第2级和第4级的加法器不需要用输出反向器进行进位产生，因此，加法器链上的反向器延迟每两级全加器抵消一次，因此可以减少4个晶体管，类似的，在乘法器这样的复杂设计中，用于产生"和"以及"进位"的输出反向器可以用于其它方面，因此可以改善电路的速度和减小面积。

Using the time-gain compensation technique to compensate for ultrasonic wave's weaking when transmitting in the air,and reduce the fluctuation of echo signal.The peak time detecting circuit which is composed of full-wave rectification circuit and differential circuit can detect the reach time of echo signal accurately.

和其他方法相比，如激光测距、微波测距等，由于声波在空气中传播速度远远小于光线和无线电波的传播速度，对于时间测量精度的要求远小于激光测距、微波测距等系统，因而超声波测距系统电路易实现、结构简单和造价低，且超声波在传播过程中不受烟雾、空气能见度等因素的影响，在各种场合均得到广泛应用。

This topology, combining four switches with double half-wave rectifier and using variable frequency control mode with a refined small times together, achieves the effect of Zero Voltage Switching and the effect of Zero Current Switching by the resonance of resonant capacitance, resonant inductor and the magnetic inductor of the transformer.

该拓扑是一种四开关和双半波组合的结构，采用固定死区的互补调频控制方式，充分利用电路本身的特征，通过谐振电感、谐振电容和变压器的激磁电感谐振，实现零电压开关和零电流开关。

This topology, combining four switches with double half-wave rectifier and using variable frequency control mode with a refined small times together, achieves the effect of Zero Voltage Switching and the effect of Zero Current Switching by the resonance of resonant capacitance, resonant inductor and the magnetic .

该拓扑是一种四开关和双半波组合的结构，采用固定死区的互补调频控制方式，充分利用电路本身的特征，通过谐振电感、谐振电容和变压器的激磁电感谐振，实现零电压开关和零电流开关。

Hardware systems, including magnetic Hall probe and standard form of the magnetic field measuring device, photoelectric isolation circuit, data storage and display devices, as well as PC-communication interface and keyboard interface.

硬件系统主要包括霍尔探头和标准磁通表对磁场的测量装置，光电隔离电路，数据存储和显示装置，以及与PC机的通讯接口和键盘接口。

Spectrophotometer 723 were introduced briefly in the paper.In order to apply it into measurement of pepsin thickness,we add temperature control system and pipe equipment into the instrument.And we redesigned the board of instrument and reedited the code.

文摘：简单介绍了723型可见分光光度计，在基本保持仪器原有机械结构的基础上，增加了温控系统和吸液装置，并对原仪器主板电路和程序进行了重新设计和编制，使它成功地应用在胃蛋白酶浓度的测量上。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。