基于DDS的轻敲式原子力显微镜探针驱动方法研究

以DDS芯片AD9833为核心,以NI6229数据采集卡的数字I/O口模拟SPI总线控制AD9833,实现了1Hz到10MHz频率范围内连续正弦信号输出,分辨率达到10-5,最小步进1Hz。数据采集卡与DDS芯片AD9833的结合为轻敲式原子力显微镜探针的驱动提供了稳定精确的正弦信号源。实验证明,此设计硬件电路结构简单,软件控制灵活,输出信号频率稳定,精确。     

基于AD9833信号发生器的设计

介绍了基于AD9833的信号发生器的设计方案。由单片机AT89S52完成系统的控制功能;幅度控制采用AD8320可编程增益放大器和D／A转换芯片TLC7528实现：功率放大电路采用高速缓冲器BUF634。最大可输出250mA的电流。实验表明该系统能够产生正弦波、方波和三角波三种周期性波形,且能实现从1Hz-2MHz的稳定输出,频率稳定度优于10^-4。     

基于DDS技术的便携式波形信号发生器

根据直接数字频率合成(DDS)技术,以可编程DDS集成芯片AD9833为核心,设计了一种便携式信号发生器,可产生正弦波和方波信号.该信号发生器由供电系统、单片机系统、DDS波形发生模块、幅度调节模块、方波发生模块、继电器输出模块等构成,介绍了相应的硬件和软件.实验表明:该信号发生器具有信号频率误差小、分辨率高、体积小、质量轻等优点.     

基于FPGA与AD9744的高精度信号源的系统设计

针对多种地面设备测试实验阶段需要模拟各种信号,以完成测试工作,设计了一种基于FPGA和AD9744的高精度模拟信号源。该信号源采用FPGA作为系统的核心控制器,AD9744为数模转换器,通过以太网接收上位机传输的指令并通过RS422接口将命令转发给模拟量板,实现14 bit的高精度D/A转换,可输出多路多幅值直流信号及交流信号。试验结果表明,该系统符合测量系统测试要求,且测试结果电压精度优于0.1%,交流信号频率精度达到0.01%,稳定性高。     

波形采集、存储与回放系统的设计

该系统以单片机和FPGA为核心控制器件,实现了波形采集、存储与回放功能。整个系统由信号调理、比较电路、采集存储、数据处理、人机交互等模块组成。信号调理模块采用高速低躁声运放AD8038实现高阻输入、幅度控制;比较电路采用LM311实现被采集信号周期的测量;数据采集模块采用AD5540芯片,在FPGA时序控制下采样;C8051F020单片机作为总控制器,与FP-GA内部的双口RAM和读写信号相结合,实现数据的存储,以及回放前数据的读取;信号输出部分采用DA芯片THS5651和高速运放AD8039相结合,实现了低输出阻抗和信号幅度的控制。经测试,系统功能齐全,波形完整,回放频率非常准确。     

合成函数信号发生器的设计

该设计是以FPGA为核心,以C8051F005单片机作为系统控制器,利用直接数字频率合成(DDFS)技术来产生所需要的波形。并且可通过无线传输任意波形数据。通过使用芯片DAC908与AD603实现信号的输出,通过NE5532的调整,使输出信号在0~5 V内可调(负载为50Ω时)。     

导波检测用激励源的设计及应用

研制出一种用AD9833和模拟乘法器MC1496合成产生信号,用单片机控制的导波检测用信号发生器。该信号发生器可根据实际检测条件进行频率、加窗形状、窗体宽度、猝发间隔程控修改等操作。运用该仪器研究分析了特定条件下不同频率,不同脉宽的激励信号的回波信号,确定了检测的最佳频率为100kHz以上,宽度为4个脉冲。运用该仪器的导波检测系统能检测出来5%缺损面积的缺陷,定位精度可达5%。     

基于DDS多功能信号源应用设计

系统采用高品质、高集成度的DDS芯片AD9851作为核心元件,用STM32进行控制输出频率、相位、幅度可调的两路信号。从AD9851输出的信号经过AD603构成的自动增益控制、信号调理电路后,经TFT液晶显示输出信号的频率和幅度等参数。信号输出稳定、精确度高、杂散性小。信号输出频率为50Hz～50MHz,幅度为10mV～2V可调,输出频率精度可达0.04Hz。同时,该信号源具有扫频输出功能。本文针对基于DDS多功能信号源应用设计进行了分析研究。     

Rife和Quinn算法在多通道数据采集系统中的应用研究

针对传统振弦式传感器采集系统精度低,通道数少,实时性差的缺点设计了一种基于ARM和AD9833多通道数据采集系统。该系统将采集调理电路、数据存储、电源供电集成化,具备精度高,实时性强等特点。系统以ARM处理器为核心,结合改进的Rife和Quinn算法对经过FFT变换后的信号得到精确频率,并根据输出信号频率与待测量之间关系进行计算,系统将计算处理后的数据通过无线或有线传输方式将监测数据传输至监测后台,实现实时在线监控监测点的相关信息,上位机解析显示数据并存入数据库。分析实验数据可知,该采集系统与传统采集系统相比精确度更高,采集速度更快,能够提高振弦式传感器的实用性。     

基于AD9833的信号发生器设计与实现

采DDS芯片AD9833为信号产生芯片,AVR单片机ATMega16L为控制器,配合外围I/O器件,设计了一种结构简便,性能优良的信号发生器.经现场验证,该信号发生器可以非常方便地生成各种频率的正弦波、三角波和方波.     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

Quantum Cooperative Robotics and Autonomy

The intersection of Quantum Technologies and Robotics Autonomy is explored in the present paper.The two areas are brought together in establishing an interdisci...     

On the Relation of Load to Average Gap in the Contact Between Surfaces with Longitudinal Roughness

A computer simulation model for the contact between longitudinally-oriented rough surfaces has been formulated. This model closely duplicates the actual surf ace contact deformation behavior by taking into account the elastic interactions between the asperities. There were no assumptions made about the shapes, or any deformation behavior of the asperities, except for their obeying the laws of elasticity. The plastic deformations on the high asperity peaks were taken into account by setting a ceiling on their contact pressures at the material hardness value. The simulations used real surface profiles which were digitized from unworn circumferentially ground steel surfaces. Each pair of these profiles was mathematically combined to form an equivalent rough profile pressing against an infinitely rigid flat and having the appropriately adjusted elastic modulus. A total of 28 different pairs of profiles were used in the simulations. Each contacting pair was subjected to 30 different load levels and the local contact pressures and deformations were calculated. The contact simulations yielded some important mathematical relationships between parameters, such as the real area of contact, average gap, and average asperity load through statistical curve fitting. Two analytical functions were generated to relate the average load to average gap and the real area of contact to load.     

三绕组变压器的双绕组等效建模及在Matpower中的应用

针对实际电网存在着大量的三绕组变压器,但国际上一些著名商业软件,如BPA仿真软件、Matpower这一权威潮流计算开源软件,均只提供双绕组变压器模型,限制了其在具有三绕组变压器的电力系统中的应用的问题,潮流计算是自主开发的电力系统各种应用软件的核心模块,因此依托国际权威开源程序进行二次开发,是一种较好的选择。对Matpower要求的数据格式进行了归纳,对变压器的一般的等值电路及带理想变压器的等值电路和带标幺值的等值电路进行了分析研究,提出了三绕组变压器转换为双绕组等效模型的建模方法,使得原先只适应双绕组变压器的潮流计算软件可以适用于三绕组变压器电网的潮流计算;最后以Matpower软件为例进行了案例计算,并用PSASP仿真软件进行对比验证。研究结果证明,所提出的建模方法是有效的。     

电站锅炉模糊风险评价方法研究与应用

针对电站锅炉风险等级评价问题,将模糊综合评价技术应用到电站锅炉风险等级评价中。开展了电站锅炉失效影响因素及模糊评价因素的重要程度分析,建立了一套科学合理适于在线评价的电站锅炉风险评价体系,提出了模糊综合评价技术与改进的模糊层次分析法相结合的模糊风险评价方法,利用改进的模糊层次分析法计算了指标体系中各层指标权重。对某一台电站锅炉的实际运行工况影响子因素进行了模糊风险评价,采用模糊合成算子进行模糊综合运算得到电了站锅炉运行工况影响子因素的评价向量。研究结果表明:电站锅炉的运行工况影响子因素的风险评价等级为第6级,失效可能性等级为小,该电站锅炉运行工况良好。     

考虑进油孔有限长滑动轴承油膜力的近似解析解

针对具有进油孔的有限长滑动轴承油膜力求解问题,采用变分原理和分离变量法,求得了有限长滑动轴承油膜压力分布的近似解析表达式。将油膜压力分布的近似解析表达式在油膜存在区域上进行积分,即得到了油膜力。将提出的计算有限长滑动轴承油膜力方法与无限长轴承模型、有限元方法的计算结果进行了比较,发现了提出的方法与有限元方法的计算结果很接近。最后,研究了进油孔位置和进油压力对油膜存在区域、油膜力等的影响,研究结果表明进油孔位置和进油压力对油膜存在区域和油膜力有较大的影响。     

Fifth International Summer School on Screw-Theory Based Methods in Robotics

正3-11 September,2014University of Bologna,Bologna,Italy www.summerscrews.org summerscrews2014.ing.unibo.it SUMMER 20SCREWS 14In 2014,our screw-theory school comes to the world's oldest university.In early September,Summer Screws'14 will gather six experts in the application of screw theory in robotics and up to 40 participants at the University of Bologna,Bologna,Italy.The school will teach attendees how to apply existing methods and empower them to develop new ones in their own research.The basic theoretical notions will be introduced in a rigorous manner,emphasizing examples,applications,and exercises.Scholarships are available.     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

交通荷载作用下桥梁结构参数识别方法

应用动力节点加载法,将作用在桥梁上的交通荷载转化为等效节点荷载,再用两步构造法识别结构物理参数.第1步,用Newmark-β方法变换结构运动方程,并用结构的加速度响应求得变换空间内的位移、速度和加速度响应;第2步,基于最小二乘原理,构造出变换空间内求解结构参数的递推式,进行结构物理参数识别.数值模拟结果表明,在交通荷载作用下,该方法能够快速、准确地进行桥梁结构参数识别.     

INDUSTRIAL ENGINEERING AND VISUALISATION-A PRODUCT DEVELOPMENT PERSPECTIVE

Taking the actual project of teaching and researching process for example, the relationship between the industrial engineering and product development is discussed. And use the novel visualization technology to support the industrial engineering and product development. How to use the new computer modeling and simulating technologies to support the product development and industrial engineering, is introduced especially. The support includes both domestic products and industrial systems. The visualization and computer technologies take a very important role in some system or multi-direction modeling, those technologies mentioned above can help the industrial engineers study the effect of design on the whole life circle, including the producing steps. So the engineers can avoid making the wrong decision which may cause bad effects on the whole industrial engineering.