J. V. Sánchez-Pérez

• Polytechnic University of Valencia

The use of metamaterials for the implementation of noise control devices in the context of environmental acoustics is a topic that has gained more and more attention in recent years. The complex design of such devices and the difficulty of their construction in real-world applications complicates the acquisition of experimental data related to thei...

Acoustic screens based on sonic crystals constitute one of the most promising technological bets of recent years in the field of environmental acoustics. Sonic crystals are defined as new materials formed by arrays of acoustic scatterers embedded in air. The design of these screens is made using powerful simulation models that provide reliable resu...

Including designer preferences in every phase of the resolution of a multi-objective optimization problem is a fundamental issue to achieve a good quality in the final solution. To consider preferences, the proposal of this paper is based on the definition of what we call a preference basis that shows the preferred optimization directions in the ob...

No PDF available ABSTRACT Acoustic screens based on sonic crystals constitute one of the most promising technological bets of recent years in the field of environmental acoustics. Sonic crystals are defined as new materials formed by arrays of acoustic scatterers embedded in air. The design of these screens is made using powerful simulation models...

The conservation and authentication of pictorial artworks is considered an important part of the preservation of cultural heritage. The use of non-destructive testing allows the obtention of accurate information about the state of pictorial artworks without direct contact between the equipment used and the sample. In particular, the use of this kin...

In this work, we present an integrated photogrammetric-acoustic technique that, together with the construction of a scaled wind tunnel, allows us to experimentally analyze the permeability behavior of a new type of acoustic screen based on a material called sonic crystal. Acoustic screens are devices used to reduce noise, mostly due to communicatio...

The correction of transcranial focused ultrasound aberrations is a relevant topic for enhancing various non-invasive medical treatments. Presently, the most widely accepted method to improve focusing is the emission through multi-element phased arrays; however, a new disruptive technology, based on 3D printed holographic acoustic lenses, has recent...

This article presents the use of advanced tools applied to the design of devices that can solve specific acoustic problems, improving the already existing devices based on classic technologies. Specifically, we have used two different configurations of a material called Sonic Crystals, which is formed by arrays of acoustic scatterers, to obtain aco...

The emergence of materials artificially designed to control the transmission of waves, generally called metamaterials, has been a hot topic in the field of acoustics for several years. The design of these metamaterials is usually carried out by overlapping different wave control mechanisms. An example of this trend is the so-called Locally Resonant...

Given a finite dimensional asymmetric normed lattice, we provide explicit formulae for the optimization of the associated (non-Hausdorff) asymmetric “distance” among a subset and a point. Our analysis has its roots and finds its applications in the current development of effective algorithms for multi-objective optimization programs. We are interes...

The correction of transcranial focused ultrasound aberrations is a relevant issue for enhancing various non-invasive medical treatments. The emission through multi-element phased arrays has been the most widely accepted method to improve focusing in recent years; however, the number and size of transducers represent a bottleneck that limits the foc...

Sonic Crystals are new heterogeneous materials formed by a crystalline array of scatterers that are embedded in a host material with different physical properties, being one of them a fluid. The great variety of physical properties of these materials in the control of the acoustic waves transmission has given rise to the development of numerous hig...

Sonic Crystals are defined as heterogeneous materials formed by arrays of scatterers embedded in a host material with different physical properties. Their particular properties in the control of acoustic waves have leaded the development of different Noise Reducing Devices technologically advanced, as Sonic Crystals Acoustics Screens (SCAS) to cont...

The correction of the aberration of transcranial focused ultrasounds is a relevant issue for enhancing various non-invasive medical treatments. Emission through multi-element phased arrays has been the most widely accepted method to reduce aberrations in recent years; however, a new disruptive technology, based on 3D printed acoustic lenses, has re...

Nowadays there are different available methods to perform simulations in acoustics. The suitability of them strongly depends on the system studied in each case. In the present work, a comparison between different methods (Multiple Scattering, Finite Elements Method and Finite Difference Time Domain) is carried out particularized to the quantificati...

Noise control is an environmental problem of first magnitude nowadays. In this work, we present a new concept of acoustic screen designed to control the specific noise generated by transport infrastructures, based on new materials called sonic crystals. These materials are formed by arrangements of acoustic scatterers in air, and provide a new and...

One of the main environmental problems of the industrialised countries is the noise, which can be defined as an unwanted or unpleasant outdoor sound generated by transport, industry and human activities in general. When it is not possible to reduce the emission of noise acting on the source, the reduction of noise levels in its transmission phase u...

This paper presents a new application of photogrammetric techniques for protecting cultural heritage. The accuracy of the method and the fact that it can be used to carry out different tests without contact between the sample and the instruments can make this technique very useful for authenticating and cataloging artworks. The application focuses...

Noise control is an environmental problem of first magnitude nowadays. In this work, we present a new concept of acoustic screen designed to control the specific noise generated by transport infrastructures, based on new materials called sonic crystals. These materials are formed by arrangements of acoustic scatterers in air, and provide a new and...

Sonic crystals have been demonstrated to be good candidates to substitute for conventional diffusers in order to overcome the need for extremely thick structures when low frequencies have to be scattered, however, their performance is limited to a narrow band. In this work, multiobjective evolutionary algorithms are used to extend the bandwidth to...

In this paper a new approach to design sound phase diffusers is presented. The acoustic properties of such diffusers are usually increased by using single objective optimization methods. Here we propose the use of a multiobjective (MO) approach to design them in order to take into account several conflicting characteristic simultaneously. Three dif...

In recent years, numerical models have acquired a leading role in the academic-scientific field for the visualization and comprehension of many physical phenomena. Acoustic diffraction is a very important and difficult phenomenon to measure, since there are other overlapping phenomena that mask it. For students of Master´s Degree in Acoustic Engine...

Visualization tools and techniques to analyze n-dimensional Pareto fronts are valuable for designers and decision makers in order to analyze straightness and drawbacks among design alternatives. Their usefulness is twofold: on the one hand, they provide a practical framework to the decision maker in order to select the preferable solution to be imp...

The design, the realization of the prototype and the acoustic standardization process of a novel periodic system made up of multiphysical phenomena scatterers as a road traffic noise reducing device are reported in this work. The structure analysed here, inspired by Sonic Crystals, has been designed following the guidelines established in recent wo...

A new generation of acoustic barriers is being introduced into the noise control market. These barriers, based on arrays of isolated scatterers, present interesting properties to be used in cities to reduce the transmitted transport noise affecting buildings. Among them, both aesthetic and continuity factors of the urban landscape may be mentioned....

Artworks are a valuable part of the World's cultural and historical heritage. Conservation and authentication of authorship are important aspects to consider in the protection of cultural patrimony. In this paper we present a novel application of a well-known method based on the phase-shift analysis of an ultrasonic signal, providing an integrated...

We report Bessel-like beam formation of acoustic waves by means of an axisymmetric grating of rigid tori. The results show that the generated beam pattern is similar to that of Bessel beams, characterized by elongated non-diffracting focal spots. A multiple foci structure is observed, due to the finite size of the lens. The dependence of the focal...

The improvement in the bandgap properties of a set of acoustic scatterers arranged according to a fractal geometry is theoretically quantified in this work using the multiple scattering theory. The analysis considers the growth process of two different arrangements of rigid cylinders in air created from a starting cluster: a classical triangular cr...

The symmetry matching between the source and the lens results in fundamental interest for lensing applications. In this work, we have modeled an axisymmetric gradient index (GRIN) lens made of rigid toroidal scatterers embedded in air considering this symmetry matching with radially symmetric sources. The sound amplification obtained in the focal s...

The symmetry matching between the source and the lens results of fundamental interest for lensing applications to amplify the intensity at the focal spot. In this work we have designed and both theoretically and experimentally reported an axisymmetric 3D metamaterial gradient index lens (GRIN) made of rigid toroidal scatterers embedded in air. By a...

En este trabajo se analizan las propiedades de propagación de las ondas sonoras en un sistema con simetría axial cuyos dispersores son toroides rígidos. El objetivo es el diseño, construcción y caracterización de un sistema para la focalización eficiente de las ondas mediante elementos pasivos (lente acústica). Mediante simulaciones numéricas en el...

Diffraction at the upper edge of a two-dimensional periodic array of finite rigid cylinders immersed in air as well as the effect on its wave propagation properties are numerically and experimentally reported in this work. The diffraction and the band gap effects, due to the finite length of the cylinders and the periodicity of the array, are the t...

In this work we present the design and the manufacturing processes, as well as the acoustics standardization tests, of an acoustic barrier formed by a set of multi-phenomena cylindrical scatterers. Periodic arrangements of acoustic scatterers embedded in a fluid medium with different physical properties are usually called Sonic Crystals. The multip...

We present the theoretical analysis of a periodic structure based on a transformational design of an axisymmetric system from a two-dimensional (2D) Sonic Crystal (SC). Applying an axial rotation of a 2D SC, we obtain a three dimensional (3D) axisymmetric structure made up of toroidal scatterers. Based on the propagating properties of the 2D system...

Inverse-designed scattering acoustical elements, called quasi-ordered structures (QOSs), are theoretically and experimentally reported in this work, showing their possibilities as attenuation devices. Multiobjective evolutionary algorithms together with multiple scattering theory have been used to design a distribution of vacancies in a phononic cr...

Design of wideband attenuation devices based on Sonic Crystals made of multi-phenomena scatterers. Société Française d'Acoustique. 283 Sonic Crystals (SCs) are periodic structures of solid scatterers embedded in a fluid. Perhaps, the most celebrated property of SCs is the presence of ranges of frequencies, known as band gaps, where only evanescent...

Noise control during its transmission is an environmental problem of first magnitude. In this work we present the standardization tests of an acoustic barrier formed by a set of multi-phenomena cylindrical scatterers. Periodic arrangements of acoustic scatterers embedded in a fluid medium with different physical properties are usually called Sonic...

The most usual method to reduce the environmental noise levels in its transmission is the use of acoustic barriers. These devices are solid systems interposed between the noise source and the receiver. One of the main mechanisms that reduce their performance is the sound waves diffraction on the upper edge of the barrier. In last years, an interest...

The properties of sonic crystals (SC) are theoretically investigated in this work by solving the inverse problem k(ω) using the extended plane wave expansion (EPWE). The solution of the resulting eigenvalue problem gives the complex band structure which takes into account both the propagating and the evanescent modes. In this work we show the compl...

The acoustical performances of regular arrays of cylindrical elements, with their axes aligned and parallel to a ground plane, have been investigated through predictions and laboratory experiments. Semi-analytical predictions based on multiple scattering theory and numerical simulations based on a boundary element formulation have been made. Measur...

Noise control during its transmission is an environmental problem of first magnitude. In this paper we present an acoustic barrier design based on second generation of sonic crystals introducing several attenuation mechanisms. Sonic crystals are defined as a set of acoustic scatterers periodically arranged with noise control properties defined by a...

The dispersion relation of periodic systems, the well-known bands structure, gives the information about the propagating modes inside the media. These bands reveal both propagating and non-propagating ranges of frequencies. It is well known that the transmission properties, with relation to the propagating modes, can be characterized by both the ba...

The effect of the presence of a finite impedance surface on the wave propagation properties of a two-dimensional periodic array of rigid cylinders with their axes perpendicular to the surface is both numerically and experimentally analyzed in this work. In this realistic situation both the incident and the scattered waves interact with these two el...

This work theoretically and experimentally reports the evanescent connections between propagating bands in periodic acoustic materials. The complex band structures obtained by solving for the $k(\omega)$ problem reveal a complete interpretation of the propagation properties of these systems. The prediction of evanescent modes, non predicted by clas...

The physical properties of a periodic distribution of absorbent resonators is used in this work to design a tunable wideband bandstop acoustic filter. Analytical and numerical simulations as well as experimental validations show that the control of the resonances and the absorption of the scatterers along with their periodic arrangement in air intr...

An acoustic metamaterial made of a two-dimensional (2D) periodic array of multi-resonant acoustic scatterers is analysed in this paper. The building blocks consist of a combination of elastic beams of Low-Density Polyethylene Foam (LDPF) with cavities of known volume. Sound inside the structure can excite elastic resonances of the material as well...

The physical properties of a periodic distribution of absorbent resonators is used in this work to design a tunable wideband bandstop acoustic filter. Analytical and numerical simulations as well as experimental validations show that the control of the resonances and the absorption of the scatterers along with their periodic arrangement in air intr...

The use of Sonic Crystals as environmental noise barriers has certain advantages from the acoustical and the constructive point of view with regard to conventional ones. One aspect do not studied yet is the acoustic interaction between the Sonic Crystals and the ground due to, up to now, this latter is not included in the analytical models used to...

The transmission of acoustic waves in a fractal distribution of rigid scatterers embedded in air is reported in this work. The Sierpinsky fractal is used to produce a compact small device containing several periodicities, therefore the fractal distribution contains several finite sonic crystals. The attenuation band produced by the fractal distribu...

The phenomenon of band-gaps typical of wave propagation in periodic materials has been a subject of extensive investigations. In acoustics, the interest is mainly related with the ability of such structures, the so-called sonic crystals, of blocking the propagation of sound at certain frequencies, acting as filters. Recently, there is an increasing...

Sonic crystals (SCs) are periodic arrangement of scatterers embedded in a fluid medium with different elastic properties. One of the main acoustical properties of these materials is the existence of ranges of frequencies where the transmission is forbidden according to Bragg's law of diffraction. This property enables the use of these devices in th...

The ability of periodic distributions of absorbent and resonant scatterers embedded in air for attenuating a wide range of frequencies is studied. The scatterers consist of a rigid core with a resonant cavity, covered by a layer of absorbent material. A preliminary numerical analysis shows the resulting combination of the three main physical phenom...

Complex Band Structures and Multiple Scattering Theory have been used in this paper to analyze the overlapping of the evanescent waves localized in point defects in Sonic Crystals. The Extended Plane Wave Expansion (EPWE) with supercell approximation gives the imaginary part of the Bloch vectors that produces the decay of the localized modes inside...

Research into properties of heterogeneous artificial materials, consisting of arrangements of rigid scatterers embedded in a medium with different elastic properties, has been intense throughout last two decades. The capability to prevent the transmission of waves in predetermined bands of frequencies -called bandgaps- becomes one of the most inter...

Evanescent modes in complete sonic crystals (SC) and SC with point defects are reported both theoretically and experimentally in this paper. Plane wave expansion (PWE) and, in general, $\omega(k)$ methods have been used to calculate band structures showing gaps that have been interpreted as ranges of frequencies where no real $k$ exists. In this wo...

We show both experimentally and theoretically the evanescent behaviour of modes in the Band Gap (BG) of finite Phononic Crystal (PC). Based on experimental and numerical data we obtain the imaginary part of the wave vector in good agreement with the complex band structures obtained by the Extended Plane Wave Expansion (EPWE). The calculated and mea...

2D Sonic Crystals (SC) prevent the transmission of the environmental noise in outdoor conditions and can be used as noise barriers. The arrangement of the acoustic scatterers is one of the factors that has an important influence on the width of the attenuation bands obtained. Up to now the scatterers have been arranged in several ways: as square or...

Scatterers with added acoustical properties are used in this work to improve the attenuation capabilities of Sonic Crystal Acoustic Barriers (SCAB). Perforated rigid cylinders add an additional independent periodicity to the SCAB introducing attenuation peaks in the range of low frequencies above the Band Gap of the structure. Band Structures calcu...

Sonic Crystal Acoustic Barriers (SCABs) are structures made of finite periodic distributions of acoustic scatterers specially indicated for attenuating noise. Periodicity of the structures produces sound attenuation in ranges of frequencies known as Band Gaps (BGs). On the other hand, resonances and absorption properties of the scatterers are also...

This paper shows a promising method for acoustic barrier design using a new acoustic material called Sonic Crystals (SCs). The configuration of these SCs is set as a multiobjective optimization problem which is very difficult to solve with conventional optimization techniques. The paper presents a new parallel implementation of a Multiobjective Evo...

An exhaustive study has been made into the potential improvement in attenuation and focusing of phononic crystal arrays resulting from the deliberate creation of vacancies. Use is made of a stochastic search algorithm based on evolutionary algorithms called the epsilon variable multi-objective genetic algorithm which, in conjunction with the applic...

Sonic Crystals (SC) are materials consisting on a periodic array of scatterers embedded in a host with different elastic properties between them. These materials present bands of frequencies related with their lattice constant, where the propagation of acoustic waves is forbidden according to the multiple scattering theory (MST). This fact becomes...

In recent years, both theoretical and experimental results have shown that the attenuation properties of periodic arrays can be improved by means of the generation of vacancies. The methodology developed involves a combination of a Multiple Scattering Theory and an optimization technique based on some Evolutionary Algorithm. Here the configuration...

During the last few years there has been increasing interest in designing devices for controlling noise. In this work experimental data and numerical simulations are presented for the noise attenuation provided by Sonic Crystals (SC). The proposed SC is formed by elongated U-profile frames made of soft material. The single scatterer of that type ma...

An improvement in the attenuation capabilities of acoustic metamaterials by means of the creation of defects is considered here as a multiobjective optimization problem. From this point of view, it is possible to define the optimum strategy in the creation of defects to achieve an important increase in acoustic attenuation in a predetermined range...

A genetic algorithm is a global search method based on a simile of the natural evolution. Genetic Algorithms have demonstrated good performance for difficult problems where the function to minimize is complicated. In this work we applied this optimization method to improve the acoustical properties of the Sonic Crystal (Martínez-Sala et Al.,1995) (...

It is well known that Genetic Algorithms (GA) is an optimization method which can be used in problems where the traditional optimization techniques are difficult to be applied. Sonic Crystals (SC) are periodic structures that present ranges of sound frequencies related with the periodicity of the structure, where the sound propagation is forbidden....

The rigourous study of band gap materials in the last years has given as a result that these systems have interesting properties for technological purposes. However, the use of this materials for specific applications requires new tools and methods that help us to obtain optimized materials and realistic simulations. In this work we present two too...

Environmental noise problems become an standard topic across the years. Acoustic barriers have been purposed as a possible solution because they can act creating an acoustic attenuation zone which depends on the sound frequency, reducing the sound transmission through it. It was demonstrated that at high sound frequencies the effect of the barriers...

Sonic crystals are defined as materials consisting of periodic distributions of acoustic scatterers in another medium with different elastic properties. These materials present two main acoustical features: they present ranges of frequencies where the acoustic wave propagation is forbidden and, moreover, they can be used to construct acoustical ref...

A phenomenological model that simulates the acoustic attenuation behavior of sonic crystals is developed in this paper. The input of the model is a set of parameters that characterizes each experimental setup, and the output is a simulation of the associated attenuation spectrum. The model consists of a combination of a multiresolution analysis bas...

No PDF available ABSTRACT In this paper we develop a phenomenological model that simulates the acoustic attenuation behavior of sonic crystals. The input of the model is a set of parameters that characterizes each experimental setup and the output is the associated simulated attenuation spectrum. The model consists of a combination of multiresoluti...

It is well known that sonic crystals are periodic structures that present acoustic band‐gap attenuation centered at frequencies related with the lattice constant of the structure. In this work we present a new approach based on genetic algorithms to create band gaps in a predetermined range of frequencies. The mechanism used by genetic algorithms t...

Sonic crystals are periodic structures that have acoustic band gaps centred at frequencies depending on the lattice constant of the array and on the direction of the incident acoustic wave. To eliminate this dependence, this work presents designed mixed structures constructed with rigid scatterers and resonators embedded in air. Specifically, ballo...

It is well known that sonic crystals are periodic structures that present acoustic band gaps attenuation centered at frequencies related with the lattice constant of the structure. We present an approach based on genetic algorithms to create band gaps in a predetermined range of frequencies. The mechanism used by genetic algorithms to achieve this...

Let λ be a countably additive vector measure with values in a separable real Hilbert space H. We define and study a pseudo metric on a Banach lattice of integrable functions related to λ that we call a λ-weighted distance. We compute the best approximation with respect to this distance to elements of the function space by the use of sequences with...

In this paper, we demonstrate that it is possible to improve the sound attenuation obtained from a mass of trees by arranging them in a periodic lattice. The outdoor experimental results have shown that the largest sound attenuation, within a certain range of frequencies, was obtained for a range of frequencies related to the array periodicity. Thi...

Geometric optic gives a good approximation to obtain the focus generated by convergent lenses in the case that their physical characteristics do not give aberrations. However, some refractive devices present aberrations due to their inherent characteristics. Sonic lenses constructed from Sonic Band Gaps (SBG) materials provide a suitable example. I...

It is well known that certain periodic structures built by repetition of elements produce sound attenuation effects as a consequence of the destructive interference of the scattered waves by these elements. The sound attenuation results that we got from transmission experiments with these kind of structures, so-called sonic crystals (SCs), led us t...

It is shown that a system made of periodic distributions of rigid cylinders in air acts as a new material which allows the construction of refractive acoustic devices for airborne sound. This kind of crystal, named sonic crystal, has low impedance and transmits the sound at subsonic velocities. Here, the fabrication and characterization of a conver...

We show that a sonic crystal made of periodic distributions of rigid cylinders in air acts as a new material which allows the construction of refractive acoustic devices for airborne sound. It is demonstrated that, in the long-wave regime, the crystal has low impedance and the sound is transmitted at subsonic velocities. Here, the fabrication and c...

The sound transmission coefficient of different multilayer partitions commonly encountered in buildings has been measured as a function of frequency. Most of the samples studied showed an increase in the sound transmission coefficient over a specific frequency, called the critical frequency, depending on the layer material. However, for partitions...

In analogy with the structures discovered by Suzuki in alkali halides, in this article we introduce a two-dimensional acoustic system consisting of a periodic distribution of impurities (vacancies) in a host array. A triangular lattice of cylindrical sound scatterers is chosen as the host. The sonic crystal, called the Suzuki phase, shows extraordi...

An analysis of the reflectance of sonic band-gap crystals consisting of square arrays of rigid cylinders in air is presented. The standing wave formed in front of the structures is studied both experimentally and theoretically. Experiments have been performed with a mobile robotized microphone that obtains pressure maps on the plane perpendicular t...

Sonic band‐gap (SBG) crystals can be made by periodic distributions of scatterers. In particular, it was found that two‐dimensional (2D) arrays of rigid cylinders in air do have acoustic band gaps that could be of application in acoustic devices related to control and filtering of sound. Here, it is pointed out that this type of SBG crystal can be...

Sound transmission properties of two-dimensional triangular arrays of rigid cylinders in which we created a lattice of vacancies with rectangular symmetry will be presented. At low frequencies, the attenuation spectra measured along the high-symmetry directions show an attenuation band corresponding to the lattice of vacancies. On the other hand, a...

We show that absolute sonic band gaps produced by two-dimensional square and triangular lattices of rigid cylinders in air can be increased by reducing the structure symmetry. In the case of square lattices, symmetry reduction is achieved by a smaller diameter cylinder placed at the center of each unit cell. For triangular lattices the reduction is...