Artículos de revistas sobre el tema "Two-way transducers"
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Wang, Yulei, Jingya Tao, Feifei Guo, Shiyang Li, Xingyi Huang, Jie Dong y Wenwu Cao. "Magnesium Alloy Matching Layer for High-Performance Transducer Applications". Sensors 18, n.º 12 (14 de diciembre de 2018): 4424. http://dx.doi.org/10.3390/s18124424.
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In this paper, we report the use of magnesium alloy (AZ31B) as the matching material for PZT-5H ultrasonic transducers. The AZ31B has an acoustic impedance of 10.3 MRayl, which provides a good acoustic impedance match for PZT-5H ultrasonic transducers in water medium based on the double matching layer theory. Two PZT-5H transducers with different center frequencies were designed and fabricated using the AZ31B. The respective center frequencies of the two fabricated transducers were 4.6 MHz and 9.25 MHz. The 4.6 MHz transducer exhibits a −6 dB bandwidth of 79% and two-way insertion loss of −11.11 dB. The 9.25 MHz transducer also shows good performance: −6 dB bandwidth of 71% and two-way insertion loss of −14.43 dB. The properties of the two transducers are superior to those of transducers using a composite matching layer, indicating that the magnesium alloy may be a promising alternative for high-performance transducers.
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Baudru, Nicolas y Pierre-Alain Reynier. "From Two-Way Transducers to Regular Function Expressions". International Journal of Foundations of Computer Science 31, n.º 06 (septiembre de 2020): 843–73. http://dx.doi.org/10.1142/s0129054120410087.
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Transducers constitute a fundamental extension of automata. The class of regular word functions has recently emerged as an important class of word-to-word functions, characterized by means of (functional, or unambiguous, or deterministic) two-way transducers, copyless streaming string transducers, and MSO-definable graph transformations. A fundamental result in language theory is Kleene’s Theorem, relating finite state automata and regular expressions. Recently, a set of regular function expressions has been introduced and used to prove a similar result for regular word functions, by showing its equivalence with copyless streaming string transducers. In this paper, we propose a direct, simplified and effective translation from unambiguous two-way transducers to regular function expressions extending the Brzozowski and McCluskey algorithm. In addition, our approach allows us to derive a subset of regular function expressions characterizing the (strict) subclass of functional sweeping transducers.
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Sklyar, Rostyslav. "A CNTFET-Based Nanowired Induction Two-Way Transducers". ISRN Nanotechnology 2012 (14 de mayo de 2012): 1–9. http://dx.doi.org/10.5402/2012/102783.
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A complex of the induction magnetic field two-way nanotransducers of the different physical values for both the external and implantable interfaces in a wide range of arrays are summarized. Implementation of the nanowires allows reliable transducing of the biosignals' partials and bringing of carbon nanotubes into circuits leading to examination of the superconducting transition. Novel sensors are based on the induction magnetic field principle, which causes their interaction with an ambient EM field. Mathematical description of both the signal and mediums defines space embracing of the relevant interfacing devices. As a result, a wide range of the nano-bio-transducers allow both delivering the variety of ionized biosignals and interface the bioEM signals with further stages of electronic systems. The space coverage and transducing values properties of the state-of-the-art magnetic interfaces are summarized, and directions for their future development are deduced.
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Gurari, Eitan M. "Two-way counter machines and finite-state transducers†". International Journal of Computer Mathematics 17, n.º 3-4 (enero de 1985): 229–35. http://dx.doi.org/10.1080/00207168508803465.
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Choffrut, Christian. "Sequences of words defined by two-way transducers". Theoretical Computer Science 658 (enero de 2017): 85–96. http://dx.doi.org/10.1016/j.tcs.2016.05.004.
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Engelfriet, Joost y Hendrik Jan Hoogeboom. "MSO definable string transductions and two-way finite-state transducers". ACM Transactions on Computational Logic 2, n.º 2 (abril de 2001): 216–54. http://dx.doi.org/10.1145/371316.371512.
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Engelfriet, Joost. "Two-way pebble transducers for partial functions and their composition". Acta Informatica 52, n.º 7-8 (4 de marzo de 2015): 559–71. http://dx.doi.org/10.1007/s00236-015-0224-3.
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Ibarra, Oscar H. y Hsu-Chun Yen. "On the containment and equivalence problems for two-way transducers". Theoretical Computer Science 429 (abril de 2012): 155–63. http://dx.doi.org/10.1016/j.tcs.2011.12.034.
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Vágvölgyi, Sándor. "Top-down tree transducers with two-way tree walking look-ahead". Theoretical Computer Science 93, n.º 1 (febrero de 1992): 43–74. http://dx.doi.org/10.1016/0304-3975(92)90211-w.
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Yang, Zhi Nian, Yuan Zhang y Yang Lei. "Fire Test on Two-Way Slab with Two Edges Clamped and Two Edges Simply Supported". Applied Mechanics and Materials 744-746 (marzo de 2015): 148–51. http://dx.doi.org/10.4028/www.scientific.net/amm.744-746.148.
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This paper describes the results of a fire test conducted on two-way slab with two edges clamped and two edges simply supported. The details of support condition, arrangement of reinforcement, position of displacement transducers and thermocouple trees are described. The experimental results such as the temperature distributions within the slab, vertical deflections and horizontal displacements are presented. The experimental results show that the temperature distribution along the slab depth was nonlinear and the temperature gradients in the slab were large. Main cracks near the clamped edges occurred on the top surface of the slab. It is shown that two-way slab with two edges clamped and two edges simply supported has good fire resistance.
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Yang, Zhi Nian y Yu Li Dong. "Fire Test on Two-way Simply Supported Concrete Slab". Applied Mechanics and Materials 405-408 (septiembre de 2013): 2380–83. http://dx.doi.org/10.4028/www.scientific.net/amm.405-408.2380.
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This paper describes the results of a fire test conducted on two-way simply supported concrete slab. The details of support condition, arrangement of reinforcement, position of displacement transducers and thermocouple trees are described. The experimental results such as the temperature distributions within the slab, vertical deflections and horizontal displacements are presented. The experimental results show that the temperature distribution along the slab depth was nonlinear and the temperature gradients in the slab were large. Three main cracks parallel to the short span direction occurred on the top surface of the slab. It is shown that two-way simply supported concrete slab has good fire resistance.
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Wormser, Maximilian, Daniel A. Kiefer, Stefan J. Rupitsch y Carolin Körner. "Comparison of Transmission Measurement Methods of Elastic Waves in Phononic Band Gap Materials". Materials 14, n.º 5 (28 de febrero de 2021): 1133. http://dx.doi.org/10.3390/ma14051133.
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Periodic cellular structures can exhibit metamaterial properties, such as phononic band gaps. In order to detect these frequency bands of strong wave attenuation experimentally, several devices for wave excitation and measurement can be applied. In this work, piezoelectric transducers are utilized to excite two additively manufactured three-dimensional cellular structures. For the measurement of the transmission factor, we compare two methods. First, the transmitted waves are measured with the same kind of piezoelectric transducer. Second, a laser Doppler vibrometer is employed to scan the mechanical vibrations of the sample on both the emitting and receiving surfaces. The additional comparison of two different methods of spatial averaging of the vibrometer data, that is, the quadratic mean and arithmetic mean, provides insight into the way the piezoelectric transducers convert the transmitted signal. Experimental results are supported by numerical simulations of the dispersion relation and a simplified transmission simulation.
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Nagy, Benedek y Zita Kovács. "On deterministic 1-limited 5′ → 3′ sensing Watson–Crick finite-state transducers". RAIRO - Theoretical Informatics and Applications 55 (2021): 5. http://dx.doi.org/10.1051/ita/2021007.
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Finite automata and finite state transducers belong to the bases of (theoretical) computer science with many applications. On the other hand, DNA computing and related bio-inspired paradigms are relatively new fields of computing. Watson–Crick automata are in the intersection of the above fields. These finite automata have two reading heads as they read the upper and lower strands of the input DNA molecule, respectively. In 5′ → 3′ Watson–Crick automata the two reading heads move in the same biochemical direction, that is, from the 5′ end of the strand to the direction of the 3′ end. However, in the double-stranded DNA, the DNA strands are directed in opposite way to each other, therefore 5′ → 3′ Watson–Crick automata read the input from the two extremes. In sensing 5′ → 3′ automata the automata sense if the two heads are at the same position, moreover, the computing process is finished at that time. Based on this class of automata, we define WK transducers such that, at each transition, exactly one input letter is being processed, and exactly one output letter is written on a normal output tape. Some special cases are defined and analyzed, e.g., when only one of the reading heads is being used and when the transducer has only one state. We also show that the minimal transducer is uniquely defined if the transducer is deterministic and it has marked output, i.e., the output letter written in a step identifies the reading head that is used in that transition. We have also used the functions ‘processing order’ and ‘reading heads’ to analyze these transducers.
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Dartois, Luc, Ismaël Jecker y Pierre-Alain Reynier. "Aperiodic String Transducers". International Journal of Foundations of Computer Science 29, n.º 05 (agosto de 2018): 801–24. http://dx.doi.org/10.1142/s0129054118420054.
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Regular string-to-string functions enjoy a nice triple characterization through deterministic two-way transducers (2DFT), streaming string transducers (SST) and MSO definable functions. This result has recently been lifted to FO definable functions, with equivalent representations by means of aperiodic 2DFT and aperiodic 1-bounded SST, extending a well-known result on regular languages. In this paper, we give three direct transformations: [Formula: see text] from 1-bounded SST to 2DFT, [Formula: see text] from 2DFT to copyless SST, and [Formula: see text] from [Formula: see text]-bounded to [Formula: see text]-bounded SST. We give the complexity of each construction and also prove that they preserve the aperiodicity of transducers. As corollaries, we obtain that FO definable string-to-string functions are equivalent to SST whose transition monoid is finite and aperiodic, and to aperiodic copyless SST.
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Filiot, Emmanuel y Pierre-Alain Reynier. "Copyful Streaming String Transducers". Fundamenta Informaticae 178, n.º 1-2 (13 de enero de 2021): 59–76. http://dx.doi.org/10.3233/fi-2021-1998.
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Copyless streaming string transducers (copyless SST) have been introduced by R. Alur and P. Černý in 2010 as a one-way deterministic automata model to define transductions of finite strings. Copyless SST extend deterministic finite state automata with a set of variables in which to store intermediate output strings, and those variables can be combined and updated all along the run, in a linear manner, i.e., no variable content can be copied on transitions. It is known that copyless SST capture exactly the class of MSO-definable string-to-string transductions, and are as expressive as deterministic two-way transducers. They enjoy good algorithmic properties. Most notably, they have decidable equivalence problem (in PSpace). On the other hand, HDT0L systems have been introduced for a while, the most prominent result being the decidability of the equivalence problem. In this paper, we propose a semantics of HDT0L systems in terms of transductions, and use it to study the class of deterministic copyful SST. Our contributions are as follows: (i)HDT0L systems and total deterministic copyful SST have the same expressive power, (ii)the equivalence problem for deterministic copyful SST and the equivalence problem for HDT0L systems are inter-reducible, in quadratic time. As a consequence, equivalence of deterministic SST is decidable, (iii)the functionality of non-deterministic copyful SST is decidable, (iv)determining whether a non-deterministic copyful SST can be transformed into an equivalent non-deterministic copyless SST is decidable in polynomial time.
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Culik, II, Karel y Juhani Karhumäki. "The Equivalence Problem for Single-Valued Two-Way Transducers (on NPDTOL Languages) is Decidable". SIAM Journal on Computing 16, n.º 2 (abril de 1987): 221–30. http://dx.doi.org/10.1137/0216018.
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Kanchanapradit, Kamin, Worakrit Thida y Sorasak Danworaphong. "Designing of ultrasonic reactor using machine learning". INTER-NOISE and NOISE-CON Congress and Conference Proceedings 268, n.º 6 (30 de noviembre de 2023): 2605–14. http://dx.doi.org/10.3397/in_2023_0381.
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Ultrasonic reactors consist of transducers that emit high-frequency acoustic waves, with designs varying based on their intended application. One such application is extraction, achieved through the cavitation effect generated by the pressure gradients produced by the ultrasound field within the medium. The cavitation effect depends on several physical parameters of the ultrasonic reactor, such as the driving frequency, acoustic energy, liquid medium, transducer attachment locations, and size and shape of the reactor. The proper design of an ultrasonic reactor is complex due to the numerous parameters that affect the distribution of ultrasonic energy, which must be concentrated and distributed in a specific way to extract effectively. To simplify the design process, this study utilizes an artificial neural network (ANN) to predict the physical dimensions and transducer locations of a square duct-shaped ultrasonic reactor with transducers attached to its sides based on the desired spatial energy distribution. The algorithm was developed using data from 1365 reactor configurations, which were numerically generated using COMSOL Multiphysics. The study tested two main models of ANNs, one using intensity profile as input and the other using power profile as input, and the results showed that each ANN had its advantages.
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Wiranata, Lalu Febrian. "PENGUKURAN LAJU ALIRAN UDARA DALAM PIPA SECARA SIMULTAN DENGAN TRANSDUSER GANDA ULTRASONIK". Indonesian Physical Review 4, n.º 1 (11 de febrero de 2021): 15. http://dx.doi.org/10.29303/ipr.v4i1.75.
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This paper aims to modification the transducer ultrasonic for measuring the distance to develop measure time of flight in the pipe with simultaneous method. To implement the application, we try to develop the microcontroller with one command transmitter and one command receiver in the same time, different from the conventional way, the transmitter and receiver work with consecutively. We try to reduce the delay time in two different transducers. In industrial, the symmetries profile must be ensured the profile always laminar. In this research, we try to use one path configuration. The result with the reference hot wire, we got the 27.76 percentage the difference of result. This is because the hot wire can measure the one path of flow in the one way of dot point.
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ALLAUZEN, CYRIL y MEHRYAR MOHRI. "N-WAY COMPOSITION OF WEIGHTED FINITE-STATE TRANSDUCERS". International Journal of Foundations of Computer Science 20, n.º 04 (agosto de 2009): 613–27. http://dx.doi.org/10.1142/s0129054109006772.
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Composition of weighted transducers is a fundamental algorithm used in many applications, including for computing complex edit-distances between automata, or string kernels in machine learning, or to combine different components of a speech recognition, speech synthesis, or information extraction system. We present a generalization of the composition of weighted transducers, n-way composition, which is dramatically faster in practice than the standard composition algorithm when combining more than two transducers. The worst-case complexity of our algorithm for composing three transducers T1, T2, and T3 resulting in T, is O(|T|Q min (d(T1)d(T3), d(T2)) + |T|E), where |·|Q denotes the number of states, |·|E the number of transitions, and d(·) the maximum out-degree. As in regular composition, the use of perfect hashing requires a pre-processing step with linear-time expected complexity in the size of the input transducers. In many cases, this approach significantly improves on the complexity of standard composition. Our algorithm also leads to a dramatically faster composition in practice. Furthermore, standard composition can be obtained as a special case of our algorithm. We report the results of several experiments demonstrating this improvement. These theoretical and empirical improvements significantly enhance performance in the applications already mentioned.
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Yang, Zhi Nian y Yu Li Dong. "Experimental Study on the Behavior of Two-Way Concrete Slab under Furnace Loading". Applied Mechanics and Materials 166-169 (mayo de 2012): 88–92. http://dx.doi.org/10.4028/www.scientific.net/amm.166-169.88.
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This paper describes the results of a furnace test conducted on two-way concrete slab with clamped edges. The details of clamped support condition, arrangement of reinforcement, position of displacement transducers and thermocouple trees are described. Detailed experimental data in the form of describing slab cracking, the temperature distributions within the slab, vertical deflections and horizontal displacements are presented. The experimental results show that the temperature distribution along the slab depth was nonlinear and the temperature gradients in the slab were large. Extensive cracks occurred on the top surface of the slab and formed in an elliptical pattern. It is shown that two-way concrete slab with clamped edges has good fire resistance.
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Haris, Kunnath, Rudy J. Kloser, Tim E. Ryan y Jacques Malan. "Deep-water calibration of echosounders used for biomass surveys and species identification". ICES Journal of Marine Science 75, n.º 3 (2 de diciembre de 2017): 1117–30. http://dx.doi.org/10.1093/icesjms/fsx206.
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Abstract Acoustic quantification of aquatic biomass using echosounders requires accurate calibration. With the advancing applications of deep-water echosounders involving moored, towed, profiling and autonomous instruments, calibration of echosounders at the operating depth is needed to ensure unbiased estimates of biomass and species identification. In this context, the deepwater calibration acoustic facility (DeCAF) was used to examine the depth-dependent variations in on-axis gain (G0) and equivalent two-way beam angle (Ψ) of three different transducers, operating at 38 (Simrad ES38-DD and MSI-38) and 120 kHz (Simrad ES120-7CD) used for biomass surveys and species identification. The analyses carried out using the sphere calibration method reveal significant variations in calibrated G0 and Ψ that in combination could result in substantial systemic biases in quantitative biomass estimation and species identification. The depth-dependent G0 variations derived using the DeCAF system are in accordance with available deep-water calibration results, demonstrating reasonable repeatability of target strength measurements (±0.6 dB) over the calibration deployments. Importantly, Ψ of the transducers was calculated to be consistently lower than the values specified by the manufacturer, and for one transducer would result in 18% change in the estimated biomass. These results highlight the potential for bias if the Ψ of transducer is not independently calculated using the actual survey echosounder.
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Živanović, Dragan y Milan Simić. "Two-stage segment linearization as part of the thermocouple measurement chain". Measurement and Control 54, n.º 1-2 (enero de 2021): 141–51. http://dx.doi.org/10.1177/0020294020986833.
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An implementation of a two-stage piece-wise linearization method for reduction of the thermocouple approximation error is presented in the paper. First, the whole thermocouple measurement chain of a transducer is described, and possible error is analysed to define the required level of accuracy for linearization of the transfer characteristics. Evaluation of linearization functions and analysis of approximation errors are performed by the virtual instrumentation software package LabVIEW. The method is appropriate for thermocouples and other sensors where nonlinearity varies a lot over the range of input values. The basic principle of this method is to first transform the abscissa of the transfer function by a linear segment look-up table in such a way that significantly nonlinear parts of the input range are expanded before a standard piece-wise linearization. In this way, applying equal-segment linearization two times has a similar effect to non-equal-segment linearization. For a given examples of the thermocouple transfer functions, the suggested method provides significantly better reduction of the approximation error, than the standard segment linearization, with equal memory consumption for look-up tables. The simple software implementation of this two-stage linearization method allows it to be applied in low calculation power microcontroller measurement transducers, as a replacement of the standard piece-wise linear approximation method.
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Mondal, Shyamal C., Paul D. Wilcox y Bruce W. Drinkwater. "Design of Two-Dimensional Ultrasonic Phased Array Transducers". Journal of Pressure Vessel Technology 127, n.º 3 (2 de marzo de 2005): 336–44. http://dx.doi.org/10.1115/1.1991873.
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Two-dimensional (2D) phased arrays have the potential to significantly change the way in which engineering components in safety critical industries are inspected. In addition to enabling a three-dimensional (3D) volume of a component to be inspected from a single location, they could also be used in a C-scan configuration. The latter would enable any point in a component to be interrogated over a range of solid angles, allowing more accurate defect characterization and sizing. This paper describes the simulation and evaluation of grid, cross and circular 2D phased array element configurations. The aim of the cross and circle configurations is to increase the effective aperture for a given number of elements. Due to the multitude of possible array element configurations a model, based on Huygens’ principle, has been developed to allow analysis and comparison of candidate array designs. In addition to the element configuration, key issues such as element size, spacing, and frequency are discussed and quantitatively compared using the volume of the 3D point spread function (PSF) as a measurand. The results of this modeling indicate that, for a given number of elements, a circular array performs best and that the element spacing should be less than half a wavelength to avoid grating lobes. A prototype circular array has been built and initial results are presented. These show that a flat bottomed hole, half a wavelength in diameter, can be imaged. Furthermore, it is shown that the volume of the 3D reflection obtained experimentally from the end of the hole compares well with the volume of the 3D PSF predicted for the array at that point.
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Zhang, Da Shan y Yu Li Dong. "Experimental Behavior of One-Way Concrete Slabs at Large Displacements". Applied Mechanics and Materials 105-107 (septiembre de 2011): 1035–39. http://dx.doi.org/10.4028/www.scientific.net/amm.105-107.1035.
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This paper presents the tensile membrane action on one-way reinforced concrete slabs, and two full-scale specimens with one edge clamped and one edge simply supported were tested at large displacements. The details of the two tests including support conditions, arrangement of reinforcements and layout of displacement transducers are described. The test results show that the load-carrying capacity of the two slabs is significantly improved due to the tensile membrane action, about 26.6% more than the predicted value using the well-established yield-line theory. Until maximum vertical displacement reached 1/15 of the span-length, the slab did not fail and carried the load steadily.
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Cassabli, Salam Bussi EP Michel, G. M. Suchkov, S. Yu Plesnetsov, R. P. Mygushchenko, O. Yu Kropachek y Yu O. Plesnetsov. "GENERATOR OF POWERFUL HIGH-FREQUENCY PACKAGE CURRENT PULSES FOR POWER SUPPLY OF ULTRASONIC ELECTROMAGNETIC-ACOUSTIC TRANSDUCERS". METHODS AND DEVICES OF QUALITY CONTROL, n.º 2(43) (24 de diciembre de 2019): 88–95. http://dx.doi.org/10.31471/1993-9981-2019-2(43)-88-95.
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It is possible to increase the sensitivity of electromagnetic-acoustic transducers by three main methods: increasing the induction of a polarizing magnetic field; increase in strength of high-frequency current in the inductor of the converter; using modern methods of processing information packet pulses excited and received from the product. The increase in magnetic field induction of the converter is limited by the capabilities of modern powerful permanent magnets. In addition, there are significant difficulties in monitoring ferromagnetic control samples, due to the large pressing force between the sample and the transducer and sticking of scale to the transducer. Usage of modern processing methods significantly complicates and increases the cost of electromagnetic-acoustic testing devices. Of the selected sensitivityincreasingmethods, the most acceptable way is to increase the power of high-frequency current generators under the condition of excitation of packet pulses. Power supply process of the converter is carried out in two stages. Meander type powerful high-frequency current pulses are excited, which ensures operation of the output transistors in key mode. Isolation of a powerful sinusoidal high-frequency packet current pulse is carried out directly on the electromagnetic - acoustic transducer, the elements of which are included in the resonant circuit with low quality factor. Based on the transistors switched in the push-pull circuit in the key mode, a small-sized generator design has been created that excites a peak current of up to 800 A in the electromagnetic-acoustic transducer and a voltage of up to 3 kV in the transducer in the frequency range 0.3 ... 8 MHz. It was experimentally determined that the new design of the probe pulse generator made it possible to increase the amplitude of pulses reflected from a flat-bottom reflector with a diameter of 2 mm with respect to the interference amplitude by more than 2 times.
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Abotaleb, Mostafa, Janusz Mindykowski, Boleslaw Dudojc y Romuald Masnicki. "Digital Communication Links Cooperating with the Analog 4-20 mA Standard for Marine Applications". Bulletin of the Polytechnic Institute of Iași. Electrical Engineering, Power Engineering, Electronics Section 67, n.º 1 (1 de marzo de 2021): 21–44. http://dx.doi.org/10.2478/bipie-2021-0002.
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Abstract The maritime industry makes a significant contribution to the globalized economy. One of the most important parts of the maritime industry is transport. Maritime transport by ships is the dominant means of transport for industrial products and food. Modern ships are increasingly automated. A characteristic feature of automation systems is the use of distributed monitoring and control systems with large distances between field devices and controllers. Among many methods of signal transmission, both in measurement and control, the dominant role in related to continuous signals is played by the two-wire 4-20 mA current standard. Despite its advantages, this standard has limitations mainly due to one-way transmission of information representing one measurement quantity. Programmable transducers are an alternative to analogue solutions. This carried out research concentrates on the full assessment of the properties of the considered methods of information transmission used so far with particular reference to the two-wire 4-20 mA standard. This assessment also takes into account the negative factors characterizing the sea-going ships, such as environmental conditions or problems resulting from the use of an isolated power grid. Additionally, a description of the available digital methods used for communication in ship automation systems will be presented. Firstly, description will be provided for HART protocol (Highway Addressable Remote Transducer), Foundation Fieldbus, Profibus PA and Modbus as communication protocols adopted by modern smart transducers as alternatives for classical analogue 4-20 mA transducers. Moreover, serial communication interfaces such as RS232, RS422 and RS485 will be discussed as means of communication between automation stations. In order to demonstrate the positive contribution for smart transmitters in measurement and control process, an experimental research has been conducted at the laboratories of Gdynia Maritime University, results of which will be discussed in detail in this article. Eventually, illustration will be provided for tank level measurement systems on a commercial ship as an example for measurement and control system mainly based on classical 4-20 mA current signal. Description will be provided for the problems associated with the system and their causes. Based on the conducted discussions, there will be recommendations of suggested solutions for such problems.
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Matiss, I. "NDT of Composite Materials - Problems and Solutions 3. Modelling of Dielectric Relaxation Phenomena". Engineering Plastics 4, n.º 3 (enero de 1996): 147823919600400. http://dx.doi.org/10.1177/147823919600400306.
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This paper discusses the modelling of frequency dependent dielectric relaxation as a support for designing transducers, the optimisation of testing conditions, identification of the internal structure of heterogeneous media, evaluation of errors and development of software for expert systems, etc. Basic principles, and the main models for relaxation behaviour are described. In this way it is possible to calculate the frequency dependence of the complex dielectric permittivity of various two- and three-component structures if the frequency dependence of the components is known.
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Matiss, I. "NDT of Composite Materials - Problems and Solutions 3. Modelling of Dielectric Relaxation Phenomena". Polymers and Polymer Composites 4, n.º 3 (enero de 1996): 195–201. http://dx.doi.org/10.1177/096739119600400306.
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This paper discusses the modelling of frequency dependent dielectric relaxation as a support for designing transducers, the optimisation of testing conditions, identification of the internal structure of heterogeneous media, evaluation of errors and development of software for expert systems, etc. Basic principles, and the main models for relaxation behaviour are described. In this way it is possible to calculate the frequency dependence of the complex dielectric permittivity of various two- and three-component structures if the frequency dependence of the components is known.
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Malinowski, Pawel, Tomasz Wandowski, Irina Trendafilova y Wiesław M. Ostachowicz. "Multi-Phased Array for Damage Localisation". Key Engineering Materials 347 (septiembre de 2007): 77–82. http://dx.doi.org/10.4028/www.scientific.net/kem.347.77.
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A method for damage localisation has been developed, which is based on the phased array idea. Four arrays of transducers, instead of only one, are used to perform a beam-forming procedure. Each array consists of nine transducers placed along a line, which are able to excite and register elastic waves. The arrays are placed in such a way that the angular difference between them is 45º and the rotation point is the middle transducer, which is common for all the arrays. The idea has been tested on a square aluminium plate modelled by the Spectral Finite Element Method. Two types of damage were considered, namely distributed damage, which was modelled as stiffness reduction, and cracks, modelled as separation of nodes in selected finite elements. The plate is excited by a wave packet (5-cycle sine modulated by the Hanning window). The whole array system is placed in the middle of the plate. Each phase array in the system acts independently and produces maps of a scanned field based on the beam-forming procedure. These maps are made of signals that represent the difference between the damaged plate signals and those from the intact plate. An algorithm was developed to join all four maps. This procedure eliminates the necessity to analyse each map individually and also gives the possibility to extract common features only. It allows to remove ambiguity and helps to localise damage more precisely than in the case of a single map. The problem for damage localisation was investigated and exemplary maps confirming the effectiveness of the system proposed were obtained. The investigation is based exclusively on numerical data.
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Zhuang, Xiao, Chao Wang y An Quan Jiang. "The technique to symmetrize domain switching hysteresis loops in LiNbO3 domain-wall nanodevices with improved polarization retention". Applied Physics Letters 120, n.º 24 (13 de junio de 2022): 243505. http://dx.doi.org/10.1063/5.0095892.
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Ferroelectric devices have wide applications in nonvolatile random-access memories, sensors, actuators, and transducers. The built-in potential at the interfaces could result in poor polarization retention. Here, we found an effective way to independently adjust two coercive fields of LiNbO3 mesa-like domain wall devices in contact to two side electrodes at the surface. Taking advantage of the electrode shielding effect on the depolarization field across an interfacial layer, the near-zero coercive field increases almost linearly with respect to the extending length of one side electrode covering the tail of the reversed domain, enabling nonvolatile ferroelectric domain wall devices in good polarization retention and fast operation speeds.
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Amarante, Tiago, Thiago H. R. Cunha, Claudio Laudares, Ana P. M. Barboza, Ana Carolina dos Santos, Cíntia L. Pereira, Vinicius Ornelas, Bernardo R. A. Neves, André S. Ferlauto y Rodrigo G. Lacerda. "Carbon nanotube-cellulose ink for rapid solvent identification". Beilstein Journal of Nanotechnology 14 (26 de abril de 2023): 535–43. http://dx.doi.org/10.3762/bjnano.14.44.
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In this work, a conductive ink based on microfibrillated cellulose (MFC) and multiwalled carbon nanotubes (MWCNTs) was used to produce transducers for rapid liquid identification. The transducers are simple resistive devices that can be easily fabricated by scalable printing techniques. We monitored the electrical response due to the interaction between a given liquid with the carbon nanotube–cellulose film over time. Using principal component analysis of the electrical response, we were able to extract robust data to differentiate between the liquids. We show that the proposed liquid sensor can classify different liquids, including organic solvents (acetone, chloroform, and different alcohols) and is also able to differentiate low concentrations of glycerin in water (10–100 ppm). We have also investigated the influence of two important properties of the liquids, namely dielectric constant and vapor pressure, on the transduction of the MFC-MWCNT sensors. These results were corroborated by independent heat flow measurements (thermogravimetric analysis). The proposed MFC-MWCNT sensor platform may help paving the way to rapid, inexpensive, and robust liquid analysis and identification.
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Andhale, Yogesh S., Faeez Masurkar y Nitesh P. Yelve. "Localization of Damages in Plain And Riveted Aluminium Specimens using Lamb Waves". March 24, No 1 (marzo de 2019): 150–65. http://dx.doi.org/10.20855/ijav.2019.24.11485.
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The Lamb wave-based localization of damage is presented here separately for the plain and riveted aluminium (Al) specimens. The first part of this paper deals with the experimental damage localization of the plain Al specimen using Lamb waves and four piezoelectric wafer (PW) transducers. The PW transducers mounted onto the specimen in a collocated way are used to actuate and sense Lamb waves. The responses are obtained for both the pristine and damaged states of the Al specimen. The signal processing is carried out on the residual response using the continuous wavelet transform (CWT), and time of arrival (TOA) data is obtained for each collocated actuator-sensor pair. The TOA data of the wave reflected from the damage is used in the two arrival time difference and astroid algorithms to locate the damage in an enclosed area. The genetic optimization (GO) method is used to further refine the location of damage within the enclosed area obtained using astroid algorithm. The second part of the paper deals with the localization of a faulty rivet in a riveted specimen. The responses are obtained in the cases of both healthy and faulty riveted specimens. The presence of a faulty rivet is indicated by the inflation in amplitude of the second harmonic. A new algorithm is therefore proposed by the authors to localize the faulty rivet, using the spectral content information. The results obtained through both the studies manifest the ability of the proposed methods for locating different types of defects and faulty rivets using an array of PW transducers.
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Garinei, Alberto y Roberto Marsili. "Development of a non-contact torque transducer based on the laser speckle contrast method". Journal of Sensors and Sensor Systems 6, n.º 2 (14 de julio de 2017): 253–58. http://dx.doi.org/10.5194/jsss-6-253-2017.
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Abstract. When a torque measurement is required, torque transducers show many drawbacks during their use: the usual limits are the need for contact and the effects on shaft line parameters. A new approach is proposed in this work: a non-contact torque meter for a machine shaft has been developed. It carries out torque measurements evaluating the torsional displacement between two distinct sections of the shaft, through the monitoring of their roughness. The sensing principle employed is the classical laser speckle contrast method. The outcoming intensity scattered by the rough surface is processed by a cross-correlation function. In this way, the angular torsion of two distinct sections is obtained. It is therefore possible to point out the applied torque knowing the shaft torsional stiffness.
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Mhammedi, Taoufik, Lionel Camberlein, Frédéric Polet, Bruno Bêche y Etienne Gaviot. "Fast Enthalpy-Sensing Microsystem Operating in Continuous Flow". Proceedings 2, n.º 13 (28 de noviembre de 2018): 771. http://dx.doi.org/10.3390/proceedings2130771.
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A new microsystem, designed to detect and measure in real time the enthalpy of mixing of two fluid-constituents is presented. A preliminary approach to arrange miniaturized batch-cells allowing detecting enthalpy of dilution or mixing is first discussed. Then, a coherent rationale leading to structure devices operating in real time is formulated, considering the straightforward assessment of heat flux transducers (HFTs) capability. Basic thermodynamic observations regarding analogy between thermal and electrical systems are highlighted prior consideration of practical examples involving mixing of water and alcohols. Fundamentals about HFTs design are highlighted before presenting an adequate way to integrate both functions of mixing and measuring the entailed heat exchange as two continuously flowing fluids interact with each other. Then, a prototype of such a dedicated device is discussed with its relevant expected performance.
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Fazi, Laura, Carla Andreani, Cadia D’Ottavi, Leonardo Duranti, Pietro Morales, Enrico Preziosi, Anna Prioriello et al. "Characterization of Conductive Carbon Nanotubes/Polymer Composites for Stretchable Sensors and Transducers". Molecules 28, n.º 4 (13 de febrero de 2023): 1764. http://dx.doi.org/10.3390/molecules28041764.
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The increasing interest in stretchable conductive composite materials, that can be versatile and suitable for wide-ranging application, has sparked a growing demand for studies of scalable fabrication techniques and specifically tailored geometries. Thanks to the combination of the conductivity and robustness of carbon nanotube (CNT) materials with the viscoelastic properties of polymer films, in particular their stretchability, “surface composites” made of a CNT on polymeric films are a promising way to obtain a low-cost, conductive, elastic, moldable, and patternable material. The use of polymers selected for specific applications, however, requires targeted studies to deeply understand the interface interactions between a CNT and the surface of such polymer films, and in particular the stability and durability of a CNT grafting onto the polymer itself. Here, we present an investigation of the interface properties for a selected group of polymer film substrates with different viscoelastic properties by means of a series of different and complementary experimental techniques. Specifically, we studied the interaction of a single-wall carbon nanotube (SWCNT) deposited on two couples of different polymeric substrates, each one chosen as representative of thermoplastic polymers (i.e., low-density polyethylene (LDPE) and polypropylene (PP)) and thermosetting elastomers (i.e., polyisoprene (PI) and polydimethylsiloxane (PDMS)), respectively. Our results demonstrate that the characteristics of the interface significantly differ for the two classes of polymers with a deeper penetration (up to about 100 μm) into the polymer bulk for the thermosetting substrates. Consequently, the resistance per unit length varies in different ranges, from 1–10 kΩ/cm for typical thermoplastic composite devices (30 μm thick and 2 mm wide) to 0.5–3 MΩ/cm for typical thermosetting elastomer devices (150 μm thick and 2 mm wide). For these reasons, the composites show the different mechanical and electrical responses, therefore suggesting different areas of application of the devices based on such materials.
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Cesaria, Maura, Adriano Colombelli, Daniela Lospinoso, Antonietta Taurino, Enrico Melissano, Roberto Rella y Maria Manera. "Long- and Short-Range Ordered Gold Nanoholes as Large-Area Optical Transducers in Sensing Applications". Chemosensors 7, n.º 1 (15 de marzo de 2019): 13. http://dx.doi.org/10.3390/chemosensors7010013.
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Unconventional lithography (such as nanosphere lithography (NSL) and colloidal lithography (CL)) is an attractive alternative to sequential and very expensive conventional lithography for the low-cost fabrication of large-area nano-optical devices. Among these, nanohole (NH) arrays are widely studied in nanoplasmonics as transducers for sensing applications. In this work, both NSL and CL are implemented to fabricate two-dimensional distributions of gold NHs. In the case of NSL, highly ordered arrays of gold NHs distributed in a hexagonal lattice onto glass substrates were fabricated by a simple and reproducible approach based on the self-assembling of close-packed 500 nm diameter polystyrene particles at an air/water interface. After the transfer onto a solid substrate, the colloidal masks were processed to reduce the colloidal size in a controllable way. In parallel, CL was implemented with short-range ordered gold NH arrays onto glass substrates that were fabricated by electrostatically-driven self-assembly of negatively charged colloids onto a polydiallyldimethylammonium (PDDA) monolayer. These distributions were optimized as a function of the colloidal adsorption time. For both approaches, controllable and reproducible procedures are presented and discussed. The optical responses of the NH structures are related to the short-range ordering level, and their good performances as refractive index transducers are demonstrated.
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Xia, Liang, Jingchun He, Yuanyuan Sun, Yi Chen, Qiong Luo, Haibo Shi, Yanmei Feng y Shankai Yin. "Comparison of Acceptable Noise Level Generated Using Different Transducers and Response Modes". Neural Plasticity 2018 (26 de junio de 2018): 1–9. http://dx.doi.org/10.1155/2018/3786489.
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The acceptable noise level (ANL) was defined by subtracting the background noise level (BNL) from the most comfortable listening level (MCL) (ANL = MCL − BNL). This study compared the ANL obtained through different methods in 20 Chinese subjects with normal hearing. ANL was tested with Mandarin speech materials using a loudspeaker or earphones, with each subject tested by himself or by the audiologist. The presentation and response modes were as follows: (1) loudspeaker with self-adjusted noise levels using audiometer controls (LS method); (2) loudspeaker with the subject signaling the audiologist to adjust speech and noise levels (LA method); (3) earphones with self-adjusted noise levels using audiometer controls (ES method); and (4) earphones with the subject signaling the audiologist to adjust speech and noise levels (EA method). ANL was calculated from three measurements with each method. There was no significant difference in the ANL obtained through different presentation modes or response modes sound. The correlations between ANL, MCL, and BNL obtained from each two methods were significant. In conclusion, the ANL in normal-hearing Mandarin listeners may not be affected by presentation modes such as a loudspeaker or earphones nor is it affected by self-adjusted or audiologist-adjusted response modes. Earphone audiometry is as reliable as sound field audiometry and provides an easy and convenient way to measure ANL.
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Fernández Gil, Oliver y Anni-Yasmin Turhan. "Answering Regular Path Queries Under Approximate Semantics in Lightweight Description Logics". Proceedings of the AAAI Conference on Artificial Intelligence 35, n.º 7 (18 de mayo de 2021): 6340–48. http://dx.doi.org/10.1609/aaai.v35i7.16787.
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Classical regular path queries (RPQs) can be too restrictive for some applications and answering such queries under approximate semantics to relax the query is desirable. While for answering regular path queries over graph databases under approximate semantics algorithms are available, such algorithms are scarce for the ontology-mediated setting. In this paper we extend an approach for answering RPQs over graph databases that uses weighted transducers to approximate paths from the query in two ways. The first extension is to answering approximate conjunctive 2-way regular path queries (C2RPQs) over graph databases and the second is to answering C2RPQs over ELH and DL-Lite_R ontologies. We provide results on the computational complexity of the underlying reasoning problems and devise approximate query answering algorithms.
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Mhammedi, Taoufik, Lionel Camberlein, Frédéric Polet, Bruno Bêche y Etienne Gaviot. "Enthalpy-Sensing Microsystem Effective in Continuous Flow". Sensors 19, n.º 3 (29 de enero de 2019): 566. http://dx.doi.org/10.3390/s19030566.
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A new microsystem designed to detect and measure in real time the enthalpy of mixing of two fluid constituents is presented. A preliminary approach to quantify the enthalpy of dilution values or mixing is first discussed. Then, a coherent rationale leading to structure devices operating in real time is formulated, considering the straightforward assessment of heat-flux transducers (HFTs) capability. Basic thermodynamic observations regarding the analogy between thermal and electrical systems are highlighted prior consideration of practical examples involving mixing water and alcohols. Fundamentals about HFT design are highlighted before presenting an adequate way to integrate both functions of mixing and measuring the entailed heat exchange as two continuously flowing fluids interact with one another. Thereby, the development of a relevant prototype of such a dedicated microsystem is discussed. Its design, fabrication and implementation under real operating conditions are presented together with its assessed performance and limits so as to highlight the advantages and shortcomings of the concept.
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Zhang, Yan Fei, Jin Liang Gong y Xiu Ting Wei. "Conceive and Design of a Six Dimensional Signals Acquisition Device". Applied Mechanics and Materials 43 (diciembre de 2010): 97–100. http://dx.doi.org/10.4028/www.scientific.net/amm.43.97.
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For most transducers, the two kinds of displacement and angular variants can not be captured at the same time. While for the unrestricted object, it often translates and rotates synchronously. For some important or special application fields, it is becoming more and more important to find a way to acquire all the six motion signals concurrently. Based on the parallel robot technology, a novel type of this kind of device is brought forth. It is composed of the end-effector, the stationary platform, and six sub-chains. It can translate along and rotate around any one of the three axes. Main structure and operation principle of this device are both described and analyzed. Measurement circuit system is designed and how to handle the twelve input signals is also explained. Finally the program flowchart and simulation examples are given.
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Mirres, Ana Carolina de Morais, Brenno Enrique Pereira de Matos da Silva, Leticia Tessaro, Diego Galvan, Jelmir Craveiro de Andrade, Adriano Aquino, Nirav Joshi y Carlos Adam Conte-Junior. "Recent Advances in Nanomaterial-Based Biosensors for Pesticide Detection in Foods". Biosensors 12, n.º 8 (27 de julio de 2022): 572. http://dx.doi.org/10.3390/bios12080572.
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Biosensors are a simple, low-cost, and reliable way to detect pesticides in food matrices to ensure consumer food safety. This systematic review lists which nanomaterials, biorecognition materials, transduction methods, pesticides, and foods have recently been studied with biosensors associated with analytical performance. A systematic search was performed in the Scopus (n = 388), Web of Science (n = 790), and Science Direct (n = 181) databases over the period 2016–2021. After checking the eligibility criteria, 57 articles were considered in this study. The most common use of nanomaterials (NMs) in these selected studies is noble metals in isolation, such as gold and silver, with 8.47% and 6.68%, respectively, followed by carbon-based NMs, with 20.34%, and nanohybrids, with 47.45%, which combine two or more NMs, uniting unique properties of each material involved, especially the noble metals. Regarding the types of transducers, the most used were electrochemical, fluorescent, and colorimetric, representing 71.18%, 13.55%, and 8.47%, respectively. The sensitivity of the biosensor is directly connected to the choice of NM and transducer. All biosensors developed in the selected investigations had a limit of detection (LODs) lower than the Codex Alimentarius maximum residue limit and were efficient in detecting pesticides in food. The pesticides malathion, chlorpyrifos, and paraoxon have received the greatest attention for their effects on various food matrices, primarily fruits, vegetables, and their derivatives. Finally, we discuss studies that used biosensor detection systems devices and those that could detect multi-residues in the field as a low-cost and rapid technique, particularly in areas with limited resources.
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Mokrani, Bilal, Renaud Bastaits, Mihaita Horodinca, Iulian Romanescu, Ioanica Burda, Régis Viguié y André Preumont. "Parallel Piezoelectric Shunt Damping of Rotationally Periodic Structures". Advances in Materials Science and Engineering 2015 (2015): 1–12. http://dx.doi.org/10.1155/2015/162782.
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This paper considers the RL shunt damping of rotationally periodic structures with an array of regularly spaced piezoelectric patches. The technique is targeted to the damping of a specific mode withnnodal diameters. For this particular case, one can take advantage of the shape of the targeted mode to organize the piezoelectric patches as a modal filter (in parallel loops) which reduces the demand on the inductors of the tuned inductive shunt. In the case of a perfectly rotationally periodic structure, it is possible to organize 4npiezoelectric transducers (PZT patches) in two parallel loops of 2npatches each. In this way, the demand on the inductors is reduced by4n2as compared to independent loops, which may allow a fully passive integration of the RL shunt in a turbomachinery application. The method is first illustrated experimentally on a circular plate; it is then applied to a prototype of an industrial bladed drum. The influence of blade mistuning is investigated.
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Vázquez, Santiago, Jorge Gosálbez, Ignacio Bosch, Alicia Carrión, Carles Gallardo y Jordi Payá. "Comparative Study of Coupling Techniques in Lamb Wave Testing of Metallic and Cementitious Plates". Sensors 19, n.º 19 (20 de septiembre de 2019): 4068. http://dx.doi.org/10.3390/s19194068.
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Lamb waves have emerged as a valuable tool to examine long plate-like structures in a faster way compared to conventional bulk wave techniques, which make them attractive in non-destructive testing. However, they present a multimodal and dispersive nature, which hinders signal identification. Oblique incidence is one of the most known methods to generate and receive Lamb waves and it is applied in different experimental arrangements with different types of sensors. In this work, several setups were conducted and compared to determine the optimal ones to launch and detect ultrasonic Lamb waves, especially in non-homogeneous specimens. The chosen arrangements were contact with angle beam transducers, immersion in a water tank, localised water coupling using conical containers and air coupling. Plates of two different materials were used, stainless steel and Portland cement mortar. Theoretical and experimental dispersion curves were compared to verify the existence of Lamb modes and good correspondence was achieved.
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Tsyhanchuk, V. V. y L. S. Shlapak. "Investigation of the properties correlation of physical and mechanical characteristics of ferromagnets based on magnetoelastic sensors of mechanical stresses". Oil and Gas Power Engineering, n.º 2(30) (5 de diciembre de 2018): 32–39. http://dx.doi.org/10.31471/1993-9868-2018-2(30)-32-39.
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The determination of the stress condition is a topical issue. At present, various non-destructive examination methods, such as strain gauge, magnetic, ultrasonic methods, and others are used to analyze pipelines stress condition. Each of them has its advantages and disadvantages. There is often the need to use several experimental non-destructive methods simultaneously. In this regard, the magnetic inspection holds a unique position. In this case a significant role is played by primary transducers, which directly perceive the effect of mechanical stresses and turn it into the electrical signal for further processing of the input information. The change of magnetic characteristics is closely connected with the physical effect on the monitored object. The advantages include the high mobility of equipment, the ability to perform control without the direct contact of transducer with the object under study. At the same time, there are several disadvantages inherent particularly in the magnetic methods – magnetoelastic hysteresis, in which there is the divergence of induction values during loading and unloading. The greatest divergence occurs in the lead-off cycle and decreases during repeated cycles. The best way is to embrace the complete information available in the hysteresis loop. Another method is not only to take measurements at one point (even if this measurement is carried out in two mutually perpendicular directions), but to perform surface sounding of the object in a certain plane. Therefore, the most efficient method is to compare the magnetic relief of loaded (in the structure) and unloaded (in reserve) pipes of one manufacturer and from one lot. Thus, using the examination method of pipelines stress condition, based on the evaluation of metal magnetic properties of pipes, creates the complex solution to the problems of reliability improvement of pipeline systems.
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VANDENPLAS, S., A. B. TEMSAMANI, Z. CISNEROS y L. VAN BIESEN. "A FREQUENCY DOMAIN INVERSION METHOD APPLIED TO OBLIQUE REFLECTED SIGNALS FROM A WATER–SEDIMENT INTERFACE". Journal of Computational Acoustics 09, n.º 02 (junio de 2001): 553–63. http://dx.doi.org/10.1142/s0218396x01000747.
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Due to the complexity of the seafloor as an acoustical system, it is very important to validate wave propagation models and test inversion methods first in the laboratory. A known sediment is placed in a water-filled tank, in such a way that a smooth water–sediment interface is obtained with minimal air bubbles retained in the sediment. Two broadband piston transducers are used to carry out reflection experiments at oblique incidence. The placement of the emitter and receiver is symmetrical with respect to a vertical plane perpendicular to the sediment surface. The aim of this work is to find physical parameters of the sediment from the reflected signals. A general viscoelastic model that considers losses due to absorption and dispersion along the propagation of the wave through the sediments is proposed. A rational transfer function is used to model the viscoelastic modulus of the bulk sediments and a comparison with constant Q viscoelastic modelling is performed. The estimation of the model parameters is elaborated using a Maximum Likelihood Estimator in the frequency domain.
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Chebanenko, V. A., I. V. Zhilyaev, A. N. Soloviev, A. V. Cherpakov y I. A. Parinov. "Numerical optimization of the piezoelectric generators". Journal of Advanced Dielectrics 10, n.º 01n02 (febrero de 2020): 2060016. http://dx.doi.org/10.1142/s2010135x20600164.
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This paper presents the application of the Pareto-based multicriteria optimization technique to problems of increasing the efficiency of piezoelectric generators (PEGs). The optimization problem was solved for two types of generators: cantilever and stack. For the cantilever generator, the task was to optimize the design in such a way as to obtain the maximum output power for a given mechanical excitation. The optimization process was divided into several stages, which significantly reduced the amount of calculations. The task of optimizing the stack type for a given form of mechanical loading consisted in finding the geometric parameters of the generator at which the output voltage and power would be maximum. In the result of solving both problems, sets of geometric design parameters of PEGs were obtained, on the basis of which efficient transducers can be developed for specific operating conditions. It turned out that this technique is more suitable for optimizing the design of cantilever generators than for stack ones in given constraints. The solution of both problems was realized using the finite element method.
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Light, G. M., J. L. Fisher, R. F. Tennis, J. S. Stolte y G. J. Hendrix. "Detection and Sizing of Defects in Control Rod Drive Mechanism Penetrations Using Eddy Current and Ultrasonics". Journal of Pressure Vessel Technology 118, n.º 3 (1 de agosto de 1996): 301–7. http://dx.doi.org/10.1115/1.2842192.
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Over the last two years, concern has been generated about the capabilities of performing nondestructive evaluation (NDE) of the closure-head penetrations in nuclear-reactor pressure vessels. These penetrations are primarily for instrumentation and control rod drive mechanisms (CRDMs) and are usually thick-walled Inconel tubes, which are shrink-fttted into the steel closure head. The penetrations are then welded between the outside surface of the penetration and the inside surface of the closure head. Stress corrosion cracks initiating at the inner surface of the penetration have been reported at several plants. Through-wall cracks in the CRDM penetration or CRDM weld could lead to loss of coolant in the reactor vessel. The CRDM penetration presents a complex inspection geometry for conventional NDE techniques. A thermal sleeve, through which pass the mechanical linkages for operating the control rods, is inserted into the penetration in such a way that only a small annulus (nominally 3 mm) exists between the thermal sleeve and inside surface of the penetration. Ultrasonic (UT) and eddy current testing (ET) techniques that could be used to provide defect detection and sizing capability were investigated. NDE techniques that could be applied inside and outside the annulus were investigated, but the major goal was to provide high defect-detection sensitivity without requiring removal of the thermal sleeve. As a result of this investigation, both ET and UT techniques for the CRDM penetrations have been developed and evaluated. Long, thin probes were designed to fit into the annulus to carry both eddy current coils and irrigated ultrasonic transducers into the region of interest. The eddy current probes were used primarily to detect cracks in the penetration while the ultrasonic transducers were used to provide an estimate of the remaining wall thickness. This paper describes the ET and UT techniques, the probes developed, and the results obtained using these probes and techniques on CRDM penetration mock-ups.
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Mota, Daniel dos Santos y Elisabetta Tedeschi. "On Adaptive Moving Average Algorithms for the Application of the Conservative Power Theory in Systems with Variable Frequency". Energies 14, n.º 4 (23 de febrero de 2021): 1201. http://dx.doi.org/10.3390/en14041201.
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The Conservative Power Theory (CPT) emerged in recent decades as a theoretical framework for coping with harmonically distorted and unbalanced electric networks of ac power systems with a high participation of converter interfaced loads and generation. The CPT measurements are intrinsically linked to moving averages (MA) over one period of the grid. If the CPT is to be used in a low-inertia isolated-grid scenario, which is subjected to frequency variations, adaptive moving averages (AMA) are necessary. This paper reviews an efficient way of computing MAs and turns it into an adaptive one. It shows that an easily available variable time delay block, from MATLAB, causes steady-state errors in the measurements when the grid frequency varies. A new variable time delay block is, thus, proposed. Nonetheless, natural pulsations in the instantaneous power slip through MAs when the discrete moving average window does not fit perfectly the continuously varying period of the grid. A method consisting of weighing two MAs is reviewed and a new and effective hybrid AMA is proposed. The CPT transducers with the different choices of AMAs are compared via computer simulations of a single-phase voltage source feeding either a linear or a nonlinear load.
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Chen, Chuanfu, Kai Wu, Kuo Lu, Qingsong Li, Chengxiang Wang, Xuezhong Wu, Beizhen Wang y Dingbang Xiao. "A Novel Mechanical Frequency Tuning Method Based on Mass-Stiffness Decoupling for MEMS Gyroscopes". Micromachines 13, n.º 7 (30 de junio de 2022): 1052. http://dx.doi.org/10.3390/mi13071052.
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MEMS gyroscopes play an important role in inertial navigation measurements, which mainly works in n = 2 mode. However, mode matching is the basis for high-precision detection, which can improve the sensitivity, resolution, and signal-to-noise ratio of the gyroscopes. An initial frequency split is inevitably generated during the manufacturing process. There are two methods to eliminate the frequency split and to achieve mode matching for the gyroscopes, which are electrostatic tuning and mechanical trimming, respectively. In this paper, we report a novel ring MEMS resonator and a novel method of mechanical frequency tuning. The most prominent characteristic of the resonator is that 16 raised mass blocks are increased in the circumferential positions of the ring uniformly. This structural design can achieve mass-stiffness decoupling, which means that punching holes on the mass blocks only affects the mass distribution but the stiffness is almost unchanged for the resonator. We verify the mass-stiffness decoupling by way of comparing the simulation with the conventional resonator. In addition, we put up an online tuning platform based on a femtosecond laser and reduce a resonator’s frequency split from 23.3 Hz to 0.4 Hz, which reveals that the frequency split is linearly related to the removed mass. These findings will have a referential significance for other transducers.
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Abdel-Sayed, S., J. Favre, J. Horisberger, S. Taub, D. Hayoz y LK von Segesser. "New bench test for venous cannula performance assessment". Perfusion 22, n.º 6 (noviembre de 2007): 411–16. http://dx.doi.org/10.1177/0267659108089759.
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Cannula design is of prime importance for venous drainage during cardiopulmonary bypass (CPB). To evaluate cannulas intended for CPB, an in vitro circuit was set up with silicone tubing between the test cannula encased in a movable preload reservoir and another static reservoir. The pressure-drop ( ΔP) value (P-drainage – P-preload) was measured using Millar pressure transducers. Flow rate ( Q) was measured using an ultrasound flowmeter. Data display and data recording were controlled using a LabView application, custom made particularly for our experiments. Our results demonstrated that ΔP, Q, and cannula resistance ( ΔP/Q) values were significantly decreased when the cannula diameter was increased for Smart and Medtronic cannulas. Smartcanula® showed 36% and 43% less resistance compared to Medtronic venous and Medtronic femoral cannulas, respectively. The cannula shape (straight- or curved-tips) did not affect the DLP cannula resistance. Out of five cannulas tested, the Smartcanula® outperforms the other commercially available cannulas. The mean ( ΔP/Q) values were 3.3 ± 0.08, 4.07 ± 0.08, 5.58 ± 0.10, 5.74 ± 0.15, and 6.45 ± 0.15 for Smart, Medtronic, Edwards, Sarns, and Gambro cannulas, respectively (two-way ANOVA, p < 0.0001). In conclusion, the present assay allows discrimination between different forms of cannula with high or low lumen resistance.