Class Of Transducers Research Articles

Sub-10 μHz/√Hz Measurement Instrumentation for 140-dB DR Frequency-Modulated MEMS Sensors

The field of frequency-modulated (FM) microelectromechanical system (MEMS) sensors is emerging as an alternative to conventional amplitude-modulated (AM) architectures, especially because of new application requirements on extended full-scale and low noise, which turn into a wide dynamic range (DR). As a consequence, a need for characterization tools dedicated to this novel class of transducers is arising. This work presents the development of the key building blocks of an instrument for the characterization of FM sensors, including an integrated circuit and external board-level components. In the instrument design, the focus is set on versatility in terms of input range frequencies and on guaranteeing a DR in the order of 140 dB. The instrument core is based on a frequency-to-digital converter, implemented through a type-II phase-locked loop with a differentiator implementing a period meter. Low-quantization noise is obtained using a high-frequency (100 MHz) time reference, while versatility is guaranteed at the same time by having programmable parameters within the integrated circuit. The instrument is tested across the 27–260-kHz input range and demonstrates sub-10- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text {Hz}/\sqrt {\text {Hz}}$ </tex-math></inline-formula> frequency noise density in the range from 10 to 100 Hz offset from the carrier and up to 100-Hz full scale. The instrument is available for testing and used by whoever is interested in its features.

Determinacy and rewriting of functional top–down and MSO tree transformations

A query is determined by a view, if the result of the query can be reconstructed from the result of the view. We consider the problem of deciding for two given (functional) tree transformations, whether one is determined by the other. If the view transformation is induced by a tree transducer that may copy, then determinacy is undecidable. For a large class of noncopying views, namely compositions of extended linear top–down tree transducers, we show that determinacy is decidable, where queries are either deterministic top–down tree transducers (with regular look-ahead) or deterministic MSO tree transducers. We also show that if a query is determined by a view, then it can be rewritten into a query that works over the view and is in the same class of transducers as the query. The proof relies on the decidability of equivalence for the considered classes of queries, and on their composition closure.

IJARCCE - Computer and Communication Engineering

A wireless sensor network is a class of transducers which is used to monitor and record the conditions of a wireless environment. Denial of service is one of the common attacks in the wireless sensor network. Vampire attack is a kind of denial of service which consumes energy that leads to draining battery-life of the nodes in the network. Since the nodes are battery powered, the network lifetime is minimized. So communication between nodes cannot be made properly and also the packet does not reach the destination during transmission. This attack can be done by either extending the path of nodes or it may form a loop in packet transmission route. In this paper, we present various algorithms on secure packet transmission against vampire attack. This survey gives different algorithms to overcome the vampire attack and provide secure packet transmission in wireless ad-hoc sensor networks.

Structural Health and Strain Monitoring Sensing through Fourier-Based Transducers

The article reports on the design of a novel class of transducers for structural health monitoring and strain sensing designed using a Fourier-based approach. The design procedure formulates the problem considering an arbitrarily shaped distribution of the sensing surface. Interrogation of the sensors is based on the generation of guided and surface acoustic waves generated in the region surrounding the transducers. The representation of the distribution of the sensing material is analyzed and designed in the spatial Fourier domain, where the emission characteristics of the transducer in relation to the interrogating wave can be tailored to a specific application. For structural health monitoring, the sensing material distribution can be defined to provide the transducers with frequency-dependent directional properties, which can be employed as part of an interrogation scheme based on generation and processing of guided waves in the structure. For strain sensing, one-dimensional and two-dimensional grating configurations monitor frequency shifts of radiation associated to local straining of the gratings. These frequency shifts can be related to the local strain components, so that a rosette-like configuration can be implemented. The article illustrates the commonalities of the design procedure, which leads to novel Lamb wave and strain transducers, and suggests the potential integration of the two sensing modalities as a single device for health and usage monitoring of structural components.

Modal transducers and Stan Ehrlich

There have been a number of transducer designs which use the dipole mode of a piezoelectric cylinder to obtain directionality since Stan Ehrlich’s early patent (with P.D. Frelich), [“Sonar Transducer,” U.S. Patent 3,290,646, December 6, 1966] was first published. There is now a whole class of transducers, called vector sensors or hydrophones, which use the dipole mode in one or more directions. In addition to this, other designs have emerged which use modes higher than the monopole and dipole modes. For example, the added use of the quadrupole mode has allowed beam patterns from cylinders which approximate patterns from piston transducers. Work on the dipole mode and higher modes of spherical transducers and arrays allow 3-D acoustical coverage from one transducer or array. This presenters interest in modal excitation from transducers and arrays began after reading Stan’s patent, and interest developed further after working with Stan at Raytheon. A review of some of the transducers and arrays which we worked on will be presented, along with more recent work based on these modal concepts.

A software tool to estimate the dynamic behaviour of the IP2C samples as sensors for didactic purposes

Ionic Polymer Polymer Composites (IP2Cs) are emerging materials used to realize motion actuators and sensors. In the former case a voltage input is able to cause the membrane to bend while in the latter case by bending an IP2C membrane, a voltage output is obtained.In this paper authors introduce a software tool able to estimate the dynamic behaviour for sensors based on IP2Cs working in air. In the proposed tool, geometrical quantities that rule the sensing properties of IP2C-based transducers are taken into account together with their dynamic characteristics. A graphical interface (GUI) has been developed in order to give a useful tool that allows the user to understand the behaviour and the role of the parameters involved in the transduction phenomena. The tool is based on the idea that a graphical user interface will allow persons not skilled in IP2C materials to observe their behaviour and to analyze their characteristics. This could greatly increase the interest of researchers towards this new class of transducers; moreover, it can support the educational activity of students involved in advanced academical courses.

Stress‐Biased Cymbals Using Shape Memory Alloys

Cymbals and other flextensional transducers demonstrate high effective displacements due to the amplifying nature of the metal endcaps, while stress‐biased RAINBOW actuators display high displacements due to enhanced 90° domain wall translational processes that result from the tensile stress in the surface region of the lead zirconate titanate (PZT) layer created during manufacturing. A new class of transducers, called stress‐biased cymbals (SBC), was developed that couples the operational principles of cymbal and stress‐biased actuators. Pre‐stressing the PZT in the cymbal was accomplished using a flat‐trained shape memory alloy endcap. Hysteresis loops were measured using a Sawyer–Tower circuit for different pre‐stress levels. Enhancements in the differential dielectric constant of more than 70% and the effective d33 of the cymbal by ∼57% were observed, suggesting greater 90° domain wall motion in the SBC compared with the standard cymbal device. The stresses developed during the fabrication process were measured and compared with theoretical models. Additional performance characteristics including dynamic dielectric constant, loss, and radial resonance frequency of the devices are also reported.

A constant beamwidth transducer for ultrasonic applications

A new class of transducers that produce uniform wide beams (∼20 deg) at ultrasonic frequencies (∼1–2 MHz) is being developed by the US Navy for ultrasonic applications. These transducers will provide a wide insonified field of view for two‐dimensional ultrasonic imaging arrays. The design features a larger volume of active material, relative to conventional planar designs, which allows the application of higher drive fields. The prototype described in this article was driven to 200 VRMS and produced a sound pressure of 203 (dB re Pa at 1 m) at a frequency of 2.0 MHz. The details of the ultrasonic constant beamwidth transducer (CBT) design, its fabrication, and measured performance are presented. The ultrasonic CBT described in this paper will soon be incorporated into the Navy’s Underwater Sound Reference Division (USRD)’s Transducer Standards Loan Program.

Uncertainty-principle noise in vacuum-tunneling transducers.

The fundamental sources of noise in a vacuum-tunneling probe used as an electromechanical transducer to monitor the location of a test mass are examined using a first-quantization formalism. We show that a tunneling transducer enforces the Heisenberg uncertainty principle for the position and momentum of a test mass monitored by the transducer through the presence of two sources of noise: the shot noise of the tunneling current and the momentum fluctuations transferred by the tunneling electrons to the test mass. We analyze a number of cases including symmetric and asymmetric rectangular potential barriers and a barrier in which there is a constant electric field. Practical configurations for reaching the quantum limit in measurements of the position of macroscopic bodies with such a class of transducers are studied.

HDTOL matching of computations of multitape automata

We discuss the technique for testing the equivalence of two deterministic automata by constructing a language that matches the computations of two equivalent automata on the same input word. Specifically, we propose to use HDTOL languages that are powerful enough to match computations of many equivalent deterministic multitape automata, and at the same time, have nice decidable properties. Using this new technique of HDTOL matching, we show that the inclusion problem between an arbitrary deterministic multitape automaton and a simple one is decidable in both directions. Further, we show that the equivalence for a restricted class of transducers based on deterministic multitape automata is decidable.

Analysis of magnetostrictive transducers by the ATILA finite element code

New magnetostrictive rare‐earth‐iron alloys offer an attractive opportunity for the design of high‐power low‐frequency transducers [F. Claeyssen, J. Acoust. Soc. Am. Suppl. 1 81, S89 (1987)]. In order to optimize the design of this particular class of transducers, a model based on a new variational principle has been derived following a classical finite element method approach. This model describes the three‐dimensional dynamic behavior of heterogeneous electrochemically coupled structures. Due to the reduced‐scalar‐potential formulation of the magnetic field, the model has been relatively easily implemented within the ATILA finite element code. In this paper, a general view of the method is given and first computation results on test structures are presented.

Fiber-optic transducers of physical field parameters (review)

A description is given of a new class of transducers (sensors) of physical field parameters in which low-loss fiber waveguides are employed. It is shown that a high sensitivity of fiber-optic transducers can be achieved for various experimental geometries. Descriptions are given of the construction of fiber-optic transducers of elastic vibrations, pressure, temperature, electromagnetic fields, and ionizing radiations. A classification is proposed for fiber-optic transducers on the basis of the physical fields detected by them, in accordance with the effect of such fields on light traveling in a fiber waveguide, and in accordance with the interaction resulting in stimulated emission from fiber waveguides.

Optical fibre transducers

Light travelling in an optical fibre may be directly modulated by external parameters such as pressure, strain, temperature, etc. Thus the fibre may form the basis of a transducer involving neither moving parts nor electrical connections. Another class of transducers uses the fibre as a means of guiding light from a monitoring point to the measuring point where the light is externally modulated. This paper presents a review of the current status of optical fibre sensors and discusses their future potential.

Electronic-circuit-design principles for parameter control of i.s.f.e.t.s and related devices

With the development of semiconductor transducers, such as i.s.f.e.t.s and related devices, a new class of transducers has been introduced in which the actual transducer function is integrated with part of the corresponding electronic circuitry. In the paper the transducer is therefore considered as being a new electronic component instead of being seen by the classical approach, in which the transducer and the electronic circuit are simply series connected. This view appears to result in unique possibilities for stabilisation and control of transducer characteristics. This is illustrated in the paper with respect to the effects of internal series resistances and the temperature sensitivity of i.s.f.e.t. devices.

Noncontacting vibration pickups

THIS digest discusses a group of methods for the measurement of vibration by devices which make no mechanical contact with the vibrating object. These devices sense the vibrations by their effect on an electric field between the pickup and the object shaken and give the magnitudes of the frequency, amplitude, and waveform of the vibratory displacements. In spite of the disadvantage of determining accelerations by measuring the frequency, amplitude, and waveform of the displacements, owing to the very large range of displacements required to hold constant acceleration through considerable frequency changes, these devices are highly useful. Effectively, they are a class of transducers for converting mechanical displacement to electric output which do not load the vibrating object.