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Global active control of sound can be achieved inside enclosures under low modal acoustic fields. However, the performance of the system depends largely on the localization of the elements of the control system. For a purely acoustic active control system in which secondary acoustic sources (loudspeakers) and pressure transducers (microphones) as error sensors are used, several optimization strategies have been proposed. These strategies usually rely on partial approximation to the problem, focusing on the study of number and localization of secondary sources without considering error transducers, or selecting the best positions of secondary sources and error transducers of an initial set of candidate locations for these elements. The strategy presented here for tonal global active noise control of steady states comprises two steps; the first is rather common for this sort of problem and its goal is to find the best locations for secondary sources and their strengths by minimizing the potential energy of the enclosure. The second step is the localization of the error transducer, which ensures the results of the first step. It is analytically demonstrated that for a single input single output system, the optimum location of error transducers is at a null pressure point of the optimally attenuated acoustic field. It is also shown that in a real case, the optimum position is that of a minimum of the optimally attenuated acoustic field. Finally, a numerical validation of this principle is carried out in a parallelipedic enclosure. [DOI: 10.1115/1.4002122] Keywords: active noise control

Transmission localized surface plasmon resonance (T-LSPR) transducers based on the characteristic surface plasmon absorption band of Au island films have become increasingly attractive. The first and main bottleneck hampering the development of T-LSPR sensors is instability, manifested as change in the surface plasmon absorbance band following immersion in organic solvents and aqueous solutions. In this paper, we innovate the platform for T-LSPR transducer by using remarkably stable and highly adhesive Au/[Al.sub.2][O.sub.3] nanocomposite film. Isolated Au nanoparticles embedded in dielectric matrix [Al.sub.2][O.sub.3] were prepared by a simple one-step radio frequency magnetron cosputtering technique. The obtained nanocomposite film is exceedingly stable during immersion in solvents, drying, and binding of different molecules; it successfully passes the adhesive tape test and sonication treatment. The superior stability and adhesion, obtained without the use of any intermediate adhesion layer or protective overlayer, is attributed to (1) the Au nanoparticles embedment and [Al.sub.2][O.sub.3] rim formation during the sputtering process and (2) the resistance of element A1 in matrix to the nucleophilic attack by the solvent molecules. Given this success, we believe that the Au/[Al.sub.2][O.sub.3] nanocomposite film holds promise as an innovative sensing platform in T-LSPR detection technology, as demonstrated here for the Pd(II) sensing process with excellent sensitivity and low detection limit.

The effect of naval operating conditions on the mechanical and electromechanical properties of [001] and [011] poled lead magnesium niobate-lead titanate (PMNT) single crystals is examined. Findings reveal the capability of the compressive, tensile and flexural strength of [001] poled PMNT in allowing its use in naval transducers.

Micromachining techniques and low-temperature ceramic composite sol-gel processing are used for the fabrication of annular array thickness-mode piezoelectric micro ultrasonic transducers (Tm-pMUTs). Results suggest that the devices resonate at approximately 60 MHz in air and 50 MHz in water.

Piezoelectric thin films on larger resonating structures were used for designing and fabricating one and two-dimensional (2-D) high frequency transducer arrays. Findings revealed a resonant frequency near 50 MHz for 40-micron-tall structures in 2-D transducer.

A fiber-optic current sensor for direct currents up to 500 kA is presented. Applications include current measurement for process control and protection in the electrowinning industry, for example at aluminum smelters. The sensor offers significant advantages with regard to performance and ease of installation compared to state-of-the-art Hall-effect-based current transducers. The sensor exploits the Faraday effect in an optical fiber and measures the path integral of the magnetic field along a closed loop around the current-carrying bus bars. The differential magnetooptic phase shift of left and right circular light waves propagating in the fiber is detected by means of a novel polarization-rotated reflection interferometer. Fiber gyroscope technology is employed for signal detection and processing. The fiber is packaged in a flexible strip of fiber reenforced epoxy, which can be installed without opening the current-carrying bus bars. Subsequent recalibration is not necessary. The sensor achieves accuracy within [+ or -] 4-0.1% over a wide range of currents and temperatures. Index Terms--Current measurement, current transducer, electroprocess, Faraday effect, fiber-optic current sensor (FOCS), high-power conversion, optical fiber devices.

Remote testing of microwave signals to 25 GHz and digital signals to 12.5 Gb/s is demonstrated through fiber-optic cables. Reflection-mode electroabsorption modulators are used as high-impedance transducers to measure voltage and inject current. Transducers are imbedded in wafer probes, printed circuit probes and microwave packages for various applications including sensing incident and reflected microwave signals, probing serial data streams on printed circuit boards, probing digital and microwave monolithic integrated circuits, and performing time-domain reflectometry. Principal advantages of this technology are that it allows test equipment to be located at large distances from the devices being tested and that broadband signals can be remotely observed with little distortion. Index Terms--Digital measurements, electric variables measurement, electroabsorption, integrated-circuit (IC) measurements, pulse measurements, scattering parameters measurement, time-domain reflectometry, transducer.

This paper describes noninvasive acoustic micromixer and transporter as well as a microfluidic subsystem (on a single silicon chip) based on the two microfluidic actuators. The actuators use a piezoelectric PZT sheet to generate about 10-12.5 MHz acoustic waves (corresponding to the PZT thickness), an array of sectored Fresnel annular rings [for the electrodes sandwiching the piezoelectric transducer (PZT)] to self-focus the acoustic waves, and acoustic streanfing effect to produce a body force for fluidic motion. The self-focused waves from the PZT array propagate through 200-[micro]m-thick silicon without any significant energy loss, and move the liquid contained in the channels and chambers (without a cover) on a micromachined silicon chip, up to 123 mm/s in-plane speed. The PZT array (consisting of a PZT sheet with an array of electrode patterns for sectored Fresnel rings) is bonded to the micromachined silicon chip to produce a last in-plane liquid motion in the open channels and chambers. When the liquid motion is produced in a channel, we have a liquid transporter; while when the motion is produced in a large area chamber, we have a micronfixer. Various channel and chamber structures have been fabricated to verify the efficacies of the liquid transport and mixing. A microfluidic subsystem integrating a micromixer, transporters and reservoirs has been shown to transport two types of liquids from their reservoirs to a mixer and to mix the liquids together within 2 s. The experimental results agree well with theoretical studies and simulation results. [1495] Index Terms--Acoustic ejector, Fresnel rings, liquid transporter; micromixel; micropump, piezoelectric transducer (PZT), self focusing.

We present a high-efficiency, low-cost wavelength division multiplexer to record cardiac optical action potentials (APs) within the myocardial wall using optical fibers. APs with signal-to-noise ratio as high as 60, without spatial or temporal averaging, and as high as 200, with median-filtering, were recorded in rabbit ventricle. Index Terms--Cardiac electrophysiology, electrooptic transducers, fluorescence, optical mapping, voltage-sensitive dye.

Many different transducers are employed for recording respiratory sounds including accelerometers and microphones in couplers. However, there is no standard lung sound transducer or any device to compare transducers so that measurements from different laboratories can be determined to be of physiologic origin rather than technical artifacts of the transducers. To address this problem, we designed and constructed a prototype of a device that can be used to compare accelerometers, microphones enclosed in couplers, and stethoscopes. The prototype device consists of a rigid chamber containing a loudspeaker that opens to an antechamber covered by a viscoelastic material with mechanical properties similar to human skin and subcutaneous tissue. When driven by a white noise source, we found the sound output at the surface to be useful to comparatively evaluate sensors between 100 and 1200 Hz where lung sounds have most of their spectral energy. We compared the viscoelastic layer to similar thicknesses of fresh meat and fat and found them to produce similar acoustic spectra. This device allows air-coupled transducers, accelerometers, and stethoscopes used in respiratory sounds measurements to be compared under physical conditions similar to their intended use. Index Terms--Accelerometers, microphones, respiratory acoustics, respiratory sounds.

This paper studies the dynamics of a self-sustained electromechanical transducer. The stability of fixed points in the linear response is examined. Their local bifurcations are investigated and different types of bifurcation likely to occur are found. Conditions for the occurrence of Hopf bifurcations are derived. Harmonic oscillatory solutions are obtained in both nonresonant and resonant cases. Their stability, is analyzed in the resonant case. Various bifurcation diagrams associated to the largest one-dimensional (1-D) numerical Lyapunov exponent are obtained, and it is found that chaos can appear suddenly, through period doubling, period adding, or torus breakdown. The extreme sensitivity of the electromechanical system to both initial conditions and tiny variations of the coupling coefficients is also outlined. The experimental study of the electromechanical system is carried out. An appropriate electronic circuit (analog simulator) is proposed for the investigation of the dynamical behavior of the electromechanical system. Correspondences are established between the coefficients of the electromechanical system model and the components of the electronic circuit. Harmonic oscillatory solutions and phase portraits are obtained experimentally. One of the most important contributions of this work is to provide a set of reliable analytical expressions (formulas) describing the electromechanical system behavior. These formulas are of great importance for design engineers as they can be used to predict the states of the electromechanical systems and respectively to avoid their destruction. The reliability of the analytical formulas is demonstrated by the very good agreement with the results obtained by both the numeric and the experimental analysis. [DOI: 10.1115/1.2172255] Keywords: electromechanical transducer, oscillatory states, analog simulation, coupled nonlinear oscillators, bifurcations, chaos

A study of a 64-element, 1.15-mm diameter annular-ring capacitive micromachined ultrasonic transducer (CMUT) array was characterized and used for forward-looking intravascular ultrasound (IVUS) imaging tests. This demonstrates that annular-ring CMUT arrays fabricated with CMOS-compatible processes are capable of forward-looking IVUS imaging, and the developed modeling tools are used to design improved IVUS imaging arrays.

A 64-kHz sandwich transducer employing a tube-shaped Terfenol-D/epoxy pseudo 1-3 magnetostrictive composite with 0.61 Terfenol-D volume fraction was developed to alleviate the intrinsic eddy-current losses in magnetostrictive alloy-based transducers. The transducer was designed to operate as a half-wave, longitudinal, mass-spring-mass, linear vibrator. It had a length of 15.7 mm and consisted of a magnetic circuit and a prestress mechanism. The magnetic circuit was composed of the composite tube, a pair of ring-shaped NdFeB permanent magnets, a drive solenoid, and a Ni-based magnetic flux guide. The distributions of the dc magnetic flux lines and magnetic field strength of the transducer were determined using an ANSYS finite-element model. The dynamic performance of the transducer was evaluated by measuring its electrical and vibrational characteristics. The results revealed that the transducer resonates at a frequency of 64.3 kHz with a strain coefficient of 39.2 nm/A, a mechanical quality factor of 39.6, and an effective coupling coefficient of 0.21. Eddy-current losses in the transducer were insignificant in the measured frequency range of 40 Hz-100 kHz. The good transducer performance indicated that Terfenol-D/epoxy pseudo 1-3 composites would be a promising magnetostrictive material for ultrasonic applications. Index Terms--Eddy-current losses, finite-element analysis, magnetostrictive composites, sandwich transducer, Terfenol-D, ultrasonics.

The regions of human chromosome 22 bound by Single Transducers and Activators of Transcription (STAT)1 and STAT2 in interferon-treated cells are identified using chromatin immunoprecipitation and DNA microarray analysis. Results demonstrate that the DNA-binding behavior of STAT1 homodimers is not conserved between the different interferon treatment conditions.

The acousto-optic tunable filter (AOTF) has optical sidelobes that are due to the acoustic field produced by the transducer. These sidelobes were analyzed by wave-vector phase matching between the optical and acoustic fields, which correlated with measurements made with a Te[O.sub.2] AOTF. A white-light point source was filtered and imaged, showing reasonably large and slowly decreasing sidelobes covering a large spectral range. This effect reduces the image quality of an AOTF system by producing faint secondary images of bright objects. The image quality can be improved with a telecentric confocal optical arrangement in which the angular shift of the sidelobes is greatly reduced, producing a much sharper image. This effect was also demonstrated experimentally with the point source. OCIS codes: 220.1000, 230.1040.

This paper presents an optomechatronic system which can detect, by triangulation, the position of a light point source, fastened onto a robot part. The sensing system consists of two positioning modules for optical transducers, which automatically follow the direction of the light point source. The system control is accomplished by means of data acquisition boards and LabVIEW programming. Index Terms--Mechatronics, optical transducer, robot sensing system.

ABSTRACT--An aluminum split Hopkinson pressure bar is instrumented with quartz force transducers and used to test low impedance materials. Two transducers are used, one at the interface between the specimen [...]

A new concept of current-mode interface circuit for differential-capacitance transducers is proposed. The solution is suitable for integration and comprises a capacitance-to-current conversion that enables low-voltage operation, provides both high speed and accuracy, and minimizes post-processing. Index Terms--Analog CMOS, capacitive transducers, current-mode, integrated sensors, low voltage.

In this paper, we report on the main aspects of the design, fabrication, and performance of a microelectromechanical system constituted by a mechanical submicrometer scale resonator (cantilever) and the readout circuitry used for monitoring its oscillation through the detection of the capacitive current. The CMOS circuitry is monolithically integrated with the mechanical resonator by a technology that allows the combination of standard CMOS processes and novel nanofabrication methods. The integrated system constitutes an example of a submicroelectromechanical system to be used as a cantilever-based mass sensor with both a high sensitivity and a high spatial resolution (on the order of [10.sup.-18] g and 300 nm, respectively). Experimental results on the electrical characterization of the resonance curve of the cantilever through the integrated CMOS readout circuit are shown. [1318] Index Terms--Capacitive transducers, CMOS analog integrated circuits, microelectromechanical devices, nanotechnology.

The 4-quadrant energy transducer (4QT) is a solution to realize both the torque and speed control of the internal combustion engine (ICE) for hybrid electric vehicles. Since the base frequency of the prototype 4QT is much higher than the industrial one, the effect of eddy current on winding current distribution is considered in this paper. A two-dimensional (2-D) eddy-current FEM model is established and used for analysis. Current density and strand current distribution are given. It is pointed out that owing to the effect of eddy current, the conductor currents are unevenly distributed within the strands of the same turn. According to the 2-D FEM analysis, when the uneven current distribution is considered, the average rms turn current is increased by 1.05 times for the stator and 1.65 times for the inner rotor, and the copper loss is increased by 1.1 times for the stator and 3.16 times for the inner rotor. Since the inner rotor slots are much deeper than the stator slots, the inner rotor current distribution is more uneven than the stator. It means that for high-frequency deep-slot machine the eddy current effect should be considered seriously. Because of the increased current and copper loss, more ventilation will be needed for the 4QT, especially for the inner rotor. The average torques of stator machine and double rotor machine meet the requirements, and the torque ripples are small owing to the skewed slots. Index Terms--Copper loss, current distribution, eddy current, 4-quadrant transducer.

Platinum (Pt) and Palladium (Pd) are used as thin metallic films for the surface acoustic wave (SAW) and interdigital transducer (IDT). The results qualify Pt and Pd langasite SAW IDTs for the modern applications in harsh environments.

A bundle of slender metal rods, each thin compared to wavelength are tightly packed within a sheath, and provides a dispersion-free waveguide that acts as a thermal buffer between a transducer and the hot fluid medium the flow that is to be measured. The sheath, made of a pipe or tube, typically has an outside diameter of 12.7 to 33 mm and usually is about 300 mm long.

This paper describes a piezoelectric micropump built on a dome-shaped diaphragm with one-way parylene valves. The micropump uses piezoelectric ZnO film (less than 10 [micro]m thick) to actuate a parylene dome diaphragm, which is fabricated with an innovative, IC-compatible process on a silicon substrate. Piezoelectric ZnO film is sputter-deposited on a parylene dome diaphragm with its C-axis oriented perpendicular to the dome surface. Two one-way check valves (made of parylene) are integrated with a piezoelectrically actuated dome diaphragm to form a multi-chip micropump. The fabricated micropump (10 x 10 x 1.6 [mm.sup.3]) consumes extremely low power (i.e., 3 mW to pump 3.2 [micro]L/min) and shows negligible leak up to 700 Pa static differential pressure. Index Terms--Ball, dome-shaped-diaphragm transducer (DSDT), micropump, parylene valves, piezoelectricity, three-dimensional (3-D) structure, wax, ZnO.

A type 5-protein phosphatase specifically dephosphorylates biologically active Pfrphytochromes and that it enhances phytochrome-mediated photoresponses. Phytochrome photoreceptors are found to develop an elaborate bio-chemical tuning mechanism for modulating the flux of light signal.

A simple one-dimensional transmission line model has previously been used to derive improved estimates for the transfer impedance of current transducers at high frequencies by taking account of the finite reflections that occur at the ports of the calibration fixture. This approach is further extended to take account of the additional reflections that occur in the system when an oversized calibration fixture is used. The success of this method is also assessed, for frequencies up to 600 MHz, using measured and computed results for the current induced on a wire inside a cavity backed aperture illuminated by a nearby antenna. Index Terms--Calibration methods, current transducers, model validation, transfer impedance.

The extraction of the coupling-of-modes (COM) model attenuation parameter gamma in a finite grating is considered. This was done using test structures comprising identical transmitting and receiving transducers and a grating centered in the acoustic channel along the propagation direction of the surface acoustic wave (SAW).

A robust on-line detection system for estimating the gate freezing-off time, which is useful for monitoring and control of injection molding, was developed based on an analysis of the correlation changes around the gate freeze-off time, as reflected in the changes of the screw movement and nozzle pressure (NP). Experiments showed that the gate freezing-off time can be accurately detected under different molding conditions. POLYM. ENG. SCI., 45:33-41, 2005. [c] 2004 Society of Plastics Engineers, INTRODUCTION In injection molding, packing-holding commences at the end of filling. Additional polymer is packed into the mold at high pressure to compensate for the material shrinkage associated with solidification. [...]

Many dynamical systems use transducers that can function both as actuators and sensors. It is possible to continuously switch the functionality of the transducer elements in such systems and effectively use each element both as an actuator and a sensor. This provides the scope for significantly reducing the number of transducer elements required for complete controllability and observability of the system and hence reduce the hardware required for controlled system operation. In this paper we advocate underactuation and undersensing in dynamical systems with the objective of reducing cost, weight, and system complexity. To this end, we first illustrate the role of switching in enhancing controllability and observability in underactuated and undersensed linear time-invariant systems and determine the switching requirement for observer-based control designs. For a proof of principle, we consider the problem of vibration suppression in a flexible beam instrumented with piezoelectric transducers. Using simulation and experiments, we demonstrate feasibility of switching the piezoelectric elements between actuator and sensor modalities and establish the merit of introducing underactuation and undersensing deliberately. [DOI: 10.1115/1.1850532]

Filters based on using single-phase, unidirectional transducers (SPUDT) consisting of Lambda/4 and wider electrodes are presented. The surface acoustic wave (SAW) devices operating at 2.45 GHz have critical dimensions of about 0.3-0.4 Mum, accessible to standard optical lithography.

Multimode techniques using Golay complementary sequences are proposed for processing the ultrasonic signal. The system is capable of echo discrimination, allowing simultaneous measurements to be made and detection of the same obstacle by different transducers without cross-talk problems.

This paper presents modelling, system identification, simulation, and experimental results for passivity-based robust control of piezo-actuated flexible beam. The flexible beam configuration considered is a cantilever aluminum beam with a piezoelectric transducer used as the actuator and tip-accelerometer as the sensor The actuator and sensor are noncollocated. The Lagrangian formulation is used to obtain mathematical model of the flexible link dynamics with piezo actuator. For control design purposes, a finite dimensional approximate model is derived using assumed modes approach. It is shown that the approximate model compares very well with the experimentally identified model. Since the system is inherently not passive, passification techniques are used to render the system robustly passive which enables the use of passivity-based feedback control design. The controller design is validated both in simulation as well as in experiments. The simulation and experimental results demonstrate the effectiveness of controller in suppressing the tip vibrations of the link. The controller design is shown to be robust to both parametric uncertainties and unmodeled dynamics. [DOI: 10.1115/1.1687392]

The functions and the features of Hedgehog proteins in both normal and pathological growth control are discussed. The Hedgehog proteins are of significant importance in the development and maintenance of tissue patterns in human adults, however Hedgehog signaling is a field which is least understood, the idiosyncratic features reflects its ancient evolutionary past.

In this paper, a transmission-line model is developed for the computation of the insertion loss of magnetostatic-surface wave transducers and measurements are carried out by the authors to check this model. In a first step of the analysis, closed-form expressions for the solution of the telegrapher's equations for the two microstrip transducers are obtained. The insertion loss is then derived from this solution as a function of three transmission-line parameters, i.e., the propagation constant and the characteristic impedance of the YIG-loaded microstrip line and the mutual inductance between the two microstrips, these quantities being, in general, complex. In a second step, these transmission-line parameters are numerically computed by applying a full-wave method-of-moments technique. Thus, the theoretical results obtained are found to be in good agreement with experimental results. Index Terms--Leakage, magnetostatic-surface waves (MSSWs), transmission-line parameters.

A flextensional device that?relies on?high electrostriction electroactive polymers is described and discussed.

The objective of this research is to develop a microelectromechanical system (MEMS)-based intelligent hybrid Biaxial Strain Transducer (BiAST) sensor for predicting railroad fatigue life based on strain history. The developed BiAST prototype was deployed to collect real-time strain data from the full-scale test track at the Transportation Technology Center (TTCI), near Pueblo, Colorado. The collected strain data were analyzed using the 'Binner' fatigue analysis program for counting the load cycles and estimating the fatigue life of a rail structure. Field-testing results of the BiAST were used to evaluate the BiAST prototype with respect to its repeatability, accuracy, and hybridization. BiAST was effective in detecting the dynamic response of a particular wheel and spurious overload events. BiAST can be used to detect passing wheels, train speed, and track condition. CE Database subject headings: Transducers; Evaluation; Fatigue life.

The present paper describes a novel generation of microchips suitable for fluorescence-based assays, such as cDNA, oligonucleotide, or protein microarrays. The new transducers consist of a fully corrugated surface coated with a thin layer of [Ta.sub.2][O.sub.5] as a high refractive index material. Tuning of the incident excitation light beam to abnormal reflection geometry results in a confinement of the energy within the thin metal oxide layer. Consequently, strong evanescent fields are generated at the surface of these microchips and fluorophores located within the fields showed up to a 2 order of magnitude increase in fluorescence intensities relative to the epifluorescence signals. We have attributed this phenomenon as evanescent resonance (ER). Due to the surface architecture, propagation distances of the incident energy and fluorescence photons are in the micrometer range, thus preventing cross talk between adjacent regions. ER microchips offer a significant increase in fluorescence intensities in both 'snapshot' fluorescence setups and commercial fluorescence scanners. The underlying principle of the novel chips is explained, and quantitative data on the fluorescence enhancement are provided. To demonstrate their potential, the novel chips are used to investigate the dependence of expression levels from metabolic genes in rat liver on drug treatment. In contrast to competitive hybridization, labeled samples were hybridized to individual ER microchips, and changes were observed by comparing with normalized data from different chips. Results obtained in gene expression profiling experiments with phenobarbital-treated rats are shown.

Advanced approaches are described for determining elastic, anelastic, and piezoelectric coefficients of langasite.

Equations for infinitesimal incremental fields superposed on finite biasing fields in a termoelestic body are obtained, using the nonlinear equations of thermoelesticity.

Results are summarized of a finite element comparison of phased array transducers involving a multi-layer composite hybrid versus a single crystal.

A linear stepper motor has been constructed with submicrometer step size and centimeter travel range. Silicon wafers with conventional dielectrics provide a basic electrostatic clamping mechanism, while a piezoelectric material serves as an electrical-to-mechanical power transducer. Movement is generated by using the inertial properties of an attached mass coupled with fast and slow expansions and contractions of the piezoelectric material. The fast transitions use the inertia of the mass to move the clamp, while the slow transitions move the mass while keeping the clamp fixed. Five prototype hand-held stepper motors have been successfully built and tested. The components of the motor fit within a pen-sized cylindrical stainless steel shell (15 cm x 1.2 cm) and deliver a displacement of 38 mm. For the given operating conditions, the tested handpieces had 1.2 mm/s advancement speeds against a 3 N load. The electrostatic clamp generates an attraction force of about 2 N using a clamp with an area of 3.75 [cm.sup.2] and 150 V across the faces. Maximum step sizes for the piezoelectric transducer (PZT) used here are slightly less than 10 [micro]m, and steps less than 100 nm can be obtained with sufficiently low PZT voltages. Motor speed can be controlled by adjusting the operating frequency. [542] Index Terms--Electrostatic devices, piezoelectric transducer (PZT) ceramics, stepper motor.

An analysis of X-Y LiNbO[subscript 3] interdigital transducers (IDT) is proposed. It is based on a fast Green's function method (GFM).