基于MAX261的程控滤波器

提出了一种以MAX261为核心,结合PIC16F877单片机的程控滤波器的基本原理与实现方案.该程控滤波器由电源电路模块、系统控制及显示模块、放大电路模块、滤波电路模块4个模块构成.对中心频率f0、Q值和工作模式进行编程控制,滤波特性好,实现了截止频率的步进调节要求,可以控制实现信号的放大倍数调节.同时利用LCD液晶显示模块实现程控滤波器性能参数的显示,整个系统性价比比较高,具有很强的实用性.     

矢量控制中电流采样值的定点Q格式处理

分析定点DSP在感应电机矢量控制中的Q格式处理问题。以矢量控制中的电流采样值的处理为例，分析了其标幺值的Q12格式表示方案。最后，给出了电流采样值定点运算的具体编程实现方法。     

激光非接触式彩管荫罩Q值测量机研制

为提高彩管荫罩Q值测量的效率和精度，提出了一种综合运用开放式数控和激光非接触式测量原理的测量方法，并研制出了Q值测量机样机。介绍了系统的主体结构，机械传动执行机构和控制结构；激光三角测量法和Q值测量的原理及软件功能。给出了测量实例数据，通过与现有接触式测量机的测量数据比较，得出了在保证测量精度的基础上，该测量机可以大大提高测量效率的结论。     

GPRS无线数据传送在远程采集系统中的应用

利用GPRS模块Q2406B和单片机W77E58，实现了在远程采集系统中应用GPRS无线传送数据。经试验证明，谊系统：运行良好，传输数据稳定。     

基于RFID的轨道交通车轮识别系统设计

针对现有轨道交通车轮机器视觉识别受环境影响的问题,基于RFID射频技术构建了轨道交通车轮识别系统。该系统是由R2000芯片和天线构成射频模块,接收和发送载波信号并对载波信号进行处理转换;控制模块对数据进行存储和发送,完成对电子标签基本信息的读写;电子标签中存有车轮的信息。同时使用多个电子标签会出现电子标签碰撞,采用Q值算法来防止电子标签碰撞。通过射频模块、控制模块和电子标签的配合,在一定的距离和速度下对轨道车轮上的电子标签进行识别,通过PC端界面实时监控识别到的电子标签数据。     

基于TMS320F2812的人机界面设计

分析TMS320F2812的特点，介绍该高速DSP芯片与慢速液晶显示模块（AT-320240Q6）连接的硬件设计方法，介绍了具有强大功能的SED1335液晶控制器，实现基于TMS320F2812的液晶图形显示，并在此基础上实现简单易行的人机界面设计。     

西门子T2000系统一层主要模块缺省值分析研究

依托最小化DCS平台，开展西门子T2000系统一层主要模块缺省值分析研究。针对控制器重启和AI模块超限两类场景，分析T2000系统一层主要模块功能，构建模块组态逻辑，测试两类故障场景下，一层模块的默认输出值，并分析研究了不同参数设置对两类故障场景下模块默认输出值的影响，为西门子T2000系统缺省值设置提供参考。     

用于射频通信领域的3-D MEMS电感设计

研究了影响3-D MEMS电感的电感值和Q值的主要因素,提出了电感值和Q值的理论计算模型.并利用该理论模型,对不同尺寸结构的三维微机械电感进行了数值模拟.根据理论计算的结果,设计了应用于射频通讯领域的高Q值3-D MEMS电感,并研究了电感制造的工艺流程.     

基于Q值选取的太阳同步回归轨道设计算法

由于太阳同步回归轨道既可以满足光照条件的要求,又可以满足时间分辨力的要求,所以成为对地观测航天器首选轨道之一。由于Q值是将太阳同步轨道和回归轨道联系起来的桥梁,所以Q值在设计太阳同步回归轨道中起着举足轻重的作用,是太阳同步回归轨道设计时最先考虑的参数。通过对太阳同步轨道和回归轨道特性的分析,可以建立Q值与太阳同步回归轨道参数之间的数学关系,此关系是设计太阳同步回归轨道的依据。通过对轨道回归特性的分析,引入了设计太阳同步回归轨道Q值的方法。最后,结合某航天任务的具体指标,利用Q值选取算法,设计了一条满足实际航天任务需求的太阳同步回归轨道。基于Q值选取的轨道设计算法从理论上找到了太阳同步轨道设计中的关键,为复杂的轨道设计工作提供了一个可靠而易行的方法。     

基于帧内调整的RFID防碰撞Q值算法的研究

在多标签识别的应用中,Q值防碰撞算法常被用来解决数据交换过程的碰撞问题。传统Q值算法在一帧识别结束后对Q值进行调整,时隙利用率不高。改进算法采用了在读写过程中动态调整Q值的策略,有效降低了碰撞时隙和空闲时隙的产生,提高了时隙利用率。在MATl AB平台下,对上述方法进行了仿真。改进算法的系统吞吐率维持在0.4以上,每秒钟约能识别345个标签,提高了系统吞吐率,减少了识别时间。且该改进算法还考虑了实际的硬件条件和ISO18000-6C标准,能在计算能力有限的微处理器上实现。     

Adaptive Q control for tapping-mode nanoscanning using a piezoactuated bimorph probe

A new approach, called adaptive Q control, for tapping-mode atomic force microscopy (AFM) is introduced and implemented on a homemade AFM setup utilizing a laser Doppler vibrometer and a piezoactuated bimorph probe. In standard Q control, the effective Q factor of the scanning probe is adjusted prior to the scanning depending on the application. However, there is a trade-off in setting the effective Q factor of an AFM probe. The Q factor is either increased to reduce the tapping forces or decreased to increase the maximum achievable scan speed. Realizing these two benefits simultaneously using standard Q control is not possible. In adaptive Q control, the Q factor of the probe is set to an initial value as in standard Q control, but then modified on the fly during scanning when necessary to achieve this goal. In this article, we present the basic theory behind adaptive Q control, the electronics enabling the online modification of the probe's effective Q factor, and the results of the experiments comparing three different methods: scanning (a) without Q control, (b) with standard Q control, and (c) with adaptive Q control. The results show that the performance of adaptive Q control is superior to the other two methods.     

SPV490Q钢焊接接头在不同浓度硫化氢溶液中的应力腐蚀开裂行为

对SPV490Q钢焊接接头的楔形张开加载(WOL)预裂纹试样在不同浓度硫化氢溶液中进行了应力腐蚀试验,测定了焊缝的应力腐蚀临界应力强度因子KISCC和应力腐蚀裂纹扩展速率da/dt。结果表明:随着H2S浓度的升高,SPV490Q钢焊缝的应力腐蚀临界应力强度因子KISCC下降,应力腐蚀裂纹扩展速率da/dt增大,焊接接头的应力腐蚀抗力降低。     

Resonant control of an atomic force microscope micro-cantilever for active Q control

Active Q control may be used to modify the effective quality (Q) factor of an atomic force microscope (AFM) micro-cantilever when operating in tapping mode. The control system uses velocity feedback to obtain an effective cantilever Q factor to achieve optimal scan speed and image resolution for the imaging environment and sample type. Time delay of the cantilever displacement signal is the most common method of cantilever velocity estimation. Spill-over effects from unmodeled dynamics may degrade the closed loop system performance, possibly resulting in system instability, when time delay velocity estimation is used. A resonant controller is proposed in this work as an alternate method of velocity estimation. This new controller has guaranteed closed loop stability, is easy to tune, and may be fitted into existing commercial AFMs with minimal modification. Images of a calibration grating are obtained using this controller to demonstrate its effectiveness.     

469Q汽油机正时同步带传动运动特性的分析研究

通过对469Q汽油机正时同步带传动运动特性的分析研究,提出了同步带横向振动的产生原因;同时,提出影响同步带振幅的主要因素是同步带跨度,并且通过试验验证了结论的正确性.结果表明,减小同步带跨度可有效减小同步带运动过程中横向振动幅度.因此,在进行发动机正时传动机构结构设计时,同步带类型确定后,其跨度大小是设计的关键.     

Resistive cooling circuits for charged particle traps using crystal resonators

The paper addresses a novel method to couple a signal from charged particles in a Penning trap to a high Q resonant circuit using a crystal resonator. Traditionally, the trap capacity is converted into a resonator by means of an inductance. The tuned circuit's Q factor is directly linked to the input impedance "seen" by the trapped particles at resonance frequency. This parallel resonance impedance is a measure of the efficiency of resistive cooling and thus it should be optimized. We propose here a commercially available crystal resonator since it exhibits a very high Q value and a parallel resonance impedance of several MΩ. The possibility to tune the parallel resonance frequency of the quartz results in filter behavior that allows covering a range of some tens of its 3dB bandwidth by means of tuning.     

超薄硅衬底氮化铝Lamb波压电谐振器

针对Lamb波压电声波传感器高品质因数(Q值)、低检测极限(LOD)和易集成的性能要求,本文基于SOI(Siliconon-insulator)硅片,通过底层硅(Handling layer)干法刻蚀和中间层(Boxing layer)自截止的方法实现2μm超薄均一的硅衬底结构,然后沉积2μm厚具备高C轴择优取向的氮化铝(AlN)压电薄膜。传感器薄膜区域外设置双端增强反射栅结构用于提高Q值,从而有效降低器件的检测极限,并通过微量水分测试验证性能。该谐振器零阶反对称模式(A0)和零阶对称模式(S0)的谐振状态的实测结果和COMSOL二维模型仿真结果一致,所制作的Lamb波谐振器A0模式的主峰Q值为703,S0模式的主峰Q值为403。微量水分测试S0模式的检测极限优于A0模式,最低检测极限值为0.06%RH。结果表明,氮化铝超薄硅衬底Lamb波压电谐振器能够实现微量水分等高精度检测。     

SPV50Q钢在湿H2S环境下抗应力腐蚀性能试验研究

用楔形张开加载(WOL)预裂纹试样研究了SPV50Q钢在湿H2S环境中的抗应力腐蚀性能。测定了SPV50Q钢母材及热影响区在湿H2S环境下的临界应力强度因子KISCC和应力腐蚀裂纹扩展速率;同时研究了H2S浓度、材质、热处理对SPV50Q钢应力腐蚀开裂的影响。     

Design and characterization of bridged loop-gap resonators for use in electron paramagnetic resonance measurements

This paper revisits the design of L and S band bridged loop-gap resonators (BLGRs) for electron paramagnetic resonance applications. A novel configuration is described and extensively characterized for resonance frequency and quality factor as a function of the geometrical parameters of the device. The obtained experimental results indicate higher values of the quality factor (Q) than previously reported in the literature, and the experimental analysis data should provide useful guidelines for BLGR design.