Energy harvesting with a slotted-cymbal transducer

A cymbal transducer is made up of a piezoceramic disk sandwiched between two dome-shaped metal endcaps. High circumferential stresses caused by flexural motion of the metal endcaps can induce the loss of mechanical input energy. Finite element analysis shows that the radial slots fabricated in metal endcaps can release the circumferential stresses, and reduce the loss of mechanical input energy that could be converted into electrical energy. In this letter, the performance of a slotted-cymbal transducer in energy harvesting was tested. The results show that the output voltage and power of the cymbal are improved. A maximum output power of around 16 mW could be harvested from a cymbal with 18 cone radial slots across a 500 kΩ resistive load, which is approximately 0.6 times more than that of the original cymbal transducer.     

一种变频器远程控制卡研制

针对变频器在CAN总线的应用需要,设计一种变频器远程控制卡,实现变频器基于CAN总线的通讯控制.     

高温压电材料的概况及发展趋势

介绍了高温压电材料的研究现状,综述了钙钛矿、钨青铜型、铋层状、碱金属铌酸盐结构体系4种不同压电陶瓷的结构及研究情况,并指出了高居里点压电陶瓷的研究方向和发展趋势。     

Free vibration of piezoelectric annular plate

INTRODUCTIONDuetotheirwideapplicationsinengineer ing ,piezoelectriccrystalplatesattractedmuchattentionandhadbeenextensivelystudiedasre ported .However,mostworkswerebasedonva rioustwo dimensionalapproximations (Dokmeci,1 980 ;Lawson ,1 942 ;Mindlin ,1 952 …     

Free vibration of piezoelectric annular plate

General solutions for coupled three dimensional equations of piezoelectric media were used in this work to obtain some analytical solutions for free vibration of piezoelectric annular plates. These solutions not only satisfy the governing equations at every point in the concerned region but also satisfy the prescribed boundary conditions at every point on the boundaries. Therefore, they are three-dimensional exact. Numerical results are finally tabulated. Project (No. 10002016) supported by the National Natural Science Foundation of China     

Dynamic responses of a multilayer piezoelectric hollow cylinder under electric potential excitation

INTRODUCTION Recently, more and more investigations have been conducted on multilayer piezoelectric media. Kharouf and Heyliger (1994) and Heyliger and Ra- mirez (2000) dealt with the free vibration problems of laminated piezoelectric cylinders and discs, respec- tively. Chen (2000) considered the free vibration of (multilayer) nonhomogeneous piezoceramic hollow spheres by employing a separation formulation for displacements. Chen (2001) developed a state-space method for free vibration …     

The Reissner-Sagoci problem for transversely isotropic piezoelectric half-space

INTRODUCTION In isotropic elasticity a class of mixed boundary value problems for elastic half-space can be classified as axisymmetric torsion. In this case the elastic field in cylinder components takes a particularly simple form consisting of only one nonzero displacement and two nonzero stress components. For this loading case, Reissner and Sagoci (1944) were possibly the first to examine a mixed boundary problem between the tangential displacement and stress on the half-space surface.…     

Exact thickness-shear resonance frequency of electroded piezoelectric crystal plates

INTRODUCTION In quartz crystal resonator design, the mass effec of the electrodes must be considered to achieve ac curate prediction of the fundamental thickness-shea frequency, as analyzed and demonstrated b Bleustein and Tiersten (1968), which is considered t be the exact frequency solutions in making necessar comparisons with solutions from two-dimensiona plate equations and deriving the correspondent cor rection factors (Mindlin, 1972). When the crysta plate is relatively thick or the…     

Active control of structural vibration by piezoelectric stack actuators

INTRODUCTION Passive methods have played an important role for a long time (Snowdon, 1973; Nelson, 1982; Pan et al., 1992) in vibration and noise control. However, with inrush of some novel engineering structures and machines, such as super high-speed machine tools, long-span bridges, thin shell structures, micro elec- tromechanical systems and so on, traditional passive control approaches are not efficient enough for con- trolling structure noise and vibration from these novel systems an…     

Application of Hamiltonian system for two-dimensional transversely isotropic piezoelectric media

INTRODUCTION The traditional method of solving solutions of the transversely isotropic piezoelectric media belongs to Lagrange formulation so that the method of sepa- ration of variables cannot be applied due to the in- volvement of high order partial differentiation in the Euclidian space and is difficult for some problems. New theoretical system or method is a key for the investigation of piezoelectric materials. Since the foundational equations (Sosa and Pak, 1990) in transversely iso…     

基于单片机的磁致伸缩位移传感器的应用

介绍了磁致伸缩位移传感器的结构、工作原理及信号特点,利用单片机对位移进行精确的测量,并对磁致伸缩位移传感器的输出模拟信号进行数字化处理,得到准确的数字信号,使得磁致伸缩位移传感器操作简单、互换性好、有效传递数据距离长.     

一体化电子式电流电压互感器研究

A high-performance current and voltage measurement system has been developed in power system.The system is composed of two parts:one current measurement element and one voltage measurement element.A Rogowski coil and a capacitive voltage divider are used respectively for the line current and voltage measurements.Active electronic components are used to modulate signal,and power supply for these components is drawn from power line via an auxiliary current transformer,Measurement signal is transmitted y optical fibers,which is resistant to electromagnetic induction and noise,With careful design and the use of digital signal processing technology,the whole system can meet 0.5% accuracy for metering and provides large dynamic range coupled with good accuracy for protective relaying use.     

A generalized plane strain theory for transversely isotropic piezoelectric plates

INTRODUCTION For moderate thickness plate containing notches or holes, neither plane stress nor plane strain theory can describe its true deformation states (Jin and Hwang, 1989). This well known drawback has mo- tivated many analytical and numerical studies carried out to determine the effect of plate thickness on the in-plane stress distribution. Pioneering work on the along depth stress components, i.e. the K-M gener- alized plane strain theory was proposed by Kane and Mindlin (1956)…     

梁型应变式载荷传感器的设计

以液压万能材料试验机的下横梁改造为工程实例,在梁型应变式载荷传感器弹性体结构优化的基础上,对采用30CrNiMoTi4V材料制作的弹性梁元件,分别按解析法和有限元法对其应变和强度进行计算,从理论上确定该传感器的最大应变方位及传感器的量程,两种方法的的理论计算结果误差小于6%.在液压万能材料试验机上实际应用表明:该传感器在最大量程为10 kN时可输出4×10-38,应变经放大器放大后可得到5 V电压输出信号,最大应力为226 MPa,能满足测试灵敏度与强度和刚度要求,传感器测试精度在1%之内.梁型载荷传感器还可应用于其他类似设备的改造,实现载荷电量输出.     

论安徽花鼓灯的艺术构成及其审美文化特征

花鼓灯作为一种融歌、舞、戏于一体的地方传统民间艺术,是淮河地域文化的杰出代表之一。在其发展的漫长过程中,深受淮河流域人们的文化传统、审美习惯的影响,呈现出斑斓浓烈的地方文化色彩和强大的艺术魅力。安徽花鼓灯艺术奔放的人物角色、铿锵的锣鼓鼓点、劲道的舞蹈动作、婉转的灯歌小戏、灵动的布巾绢扇,形成了独特而鲜明的艺术风格,以"秀美、壮美、华美、优美、精美"五美并举的形式揭示安徽花鼓灯艺术的审美特征。     

Modeling of sensor function for piezoelectric bender elements

An analytical sandwich beam model for piezoelectric bender elements is derived based on the first-order shear deformation theory （FSDT）, which assumes a single rotation angle for the whole cross-section and a quadratic distribution for coupled electric potential in piezoelectric layers. Shear coefficient is introduced to correct the effect of transverse shear strain on shear force and the electric displacement integration. Static and free vibration analyses of simply-supported bender elements are carried out for the sensor function. The results illustrate the high accuracy of the present model compared with the exact 2D solutions.     

智能工业pH值变送器的设计

该文介绍了一种采用89C52单片机设计的pH值智能变送器,将工业现场的0～14 pH值变送为4～20 mA的标准信号输出.该变送器采用玻璃电极作为测量传感器,采用两片7650运放组成的差动电路作为输入电路,提高了抗干扰能力,采用Ptl00热电阻测量被测介质的温度,对pH值进行温度补偿,提高了测量精度.文中介绍了硬件电路的设计原理及软件框图.     

A symplectic eigensolution method in transversely isotropic piezoelectric cylindrical media

INTRODUCTION Since the phenomenon of piezoelectricity in natural crystals was discovered in 1880, it has been applied in many fields, such as smart structure, sensing devices and active control, because of its special properties. Combining electrical behavior with mechanical deformation is the special property which attracted great interest of researchers. Many models have been developed for studying piezoelec- tric effects. Dunn and Wienecke (1996) used Green’s functions for transverse…     

Analytical modelling and free vibration analysis of piezoelectric bimorphs

INTRODUCTION Piezoelectric bimorphs (or benders), a special type of piezoelectric device, which can produce flexural deformation significantly larger than the length or thickness deformation of the individual piezoelectric layers, have been widely used as elec- troacoustic transducers, medical devices and micro- robot due to their characteristics of easy miniaturiza- tion, high positioning accuracy, sensitive response, and large displacement (e.g., Shirley and Hampton, 1978; Ha and Kim, 2…     

变频器在切削力测量实验中的应用

切削力是金属切削中的重要参数之一,与切削速度呈驼峰曲线关系。为了使车削中的切削速度不受工件直径变化的影响而得到清晰完整的驼峰曲线,采用变频器对机床主电机进行无级调速,从而使主轴转速由主电机工作频率和调速手柄共同决定。实验结果表明无级调速可得到较理想的驼峰曲线。