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Membrane-type acoustic metamaterials (MAMs) recently have been emerged to display useful sound attenuation properties in a low-frequency regime. The purpose of this paper is to present an analytical approach to investigate the transmission loss (TL) of a square membrane-ring structure of MAM. The geometrical effects of ring mass on the TL peak and dip frequencies of the MAM are obtained and discussed.

In this paper, based on the wave propagation and vibration theory, considering the effects of ring mass and acoustic pressure on the membrane, an analytical model is presented to analyze acoustic response of MAM.

Multiple peak frequencies and wide bandwidth appear in the membrane-ring structure, and they can be tuned by changing the location or numbers of the ring mass on the membrane. It is a useful method for designing such type of metamaterial.

In this paper, an analytical method is presented to evaluate the effects of ring geometric on the TL performance of square membrane-type locally resonant metamaterial. It is proved that achieving broadband and multi-peak TL profile in a single cell can indeed happen by increasing additional ring mass. The TL and frequency bandwidth can be tuned by changing the location, adding numbers and varying mass distribution of the ring masses on the membrane.

Limitations in traditional manufacturing methods currently employed in the production of acoustic devices, restricts the development of design led performance improvements. These devices are used to control sound energy and are commonly employed for tailoring room acoustics. solid freeform fabrication allows the production of acoustic structures more complex than traditionally manufactured devices. This paper aims to focus on a novel absorber based on destructive interference, considering performance, design and manufacture.

Selective laser sintering has been used in the investigation of the performance and manufacturing possibilities and limitations of a novel destructive interference absorber. Validation of the absorber performance is benchmarked against a conventional resonant absorber and compared to published results. The implications for acoustic devise design, the advances and limitations in manufacture using solid freeform fabrication techniques and potential applications are discussed.

An original absorber design has been shown to exhibit comparable acoustic absorption to that of a traditional solution. The nature of the geometry of the novel absorber demonstrates that the design flexibility afforded by solid freeform fabrication processes holds potential for applications incorporating new types of acoustic absorber. The use of solid freeform fabrication has demonstrated its potential to the application of acoustics, and has highlighted limitations due to post‐processing, material strength and the precision of the selectivity process.

Solid freeform fabrication techniques enable a new family of specifically engineered acoustic absorbers capable of incorporating performance benefits over conventional absorbers.

This paper focuses on room acoustic applications, the creation of high performance, conformal absorbers, applicable to a wide range of applications within the aerospace, automotive and construction industries, where space, weight and performance are key criteria.

In this paper, we explore how corporations use visual artifacts to translate and recontextualize a globally theorized managerial concept (CSR) into a local setting (Austria). In our analysis of the field-level visual discourse, we analyze over 1,600 images in stand-alone CSR reports of publicly traded corporations. We borrow from framing analysis and structural linguistics to show how the meaning structure underlying a multifaceted construct like CSR is constituted by no more than a relatively small number of fundamental dimensions and rhetorical standpoints (topoi). We introduce the concept of imageries-of-practice to embrace the critical role that shared visual language plays in the construction of meaning and the emergence of field-level logics. In particular, we argue that imageries-of-practice, compared to verbal vocabularies, are just as well equipped to link locally resonating symbolic representations and globally diffusing practices, thus expressing both the material and ideational dimension of institutional logics in processes of translation. We find that visual rhetoric used in the Austrian discourse emphasizes the qualities of CSR as a bridging concept, and facilitates the mediation of inconsistencies in several ways: By translating abstract global ideas into concrete local knowledge, imageries-of-practice aid in mediating spatial oppositions; by linking the past, present, and future, they bridge time; by mediating between different institutional spheres and their divergent logics, they appease ideational oppositions and reduce institutional complexity; and, finally, by connecting questionable claims with representations of authenticity, they aid in overcoming credibility gaps.

In this paper, we explore how corporations use visual artifacts to translate and recontextualize a globally theorized managerial concept (CSR) into a local setting (Austria). In our analysis of the field-level visual discourse, we analyze over 1,600 images in stand-alone CSR reports of publicly traded corporations. We borrow from framing analysis and structural linguistics to show how the meaning structure underlying a multifaceted construct like CSR is constituted by no more than a relatively small number of fundamental dimensions and rhetorical standpoints (topoi). We introduce the concept of imageries-of-practice to embrace the critical role that shared visual language plays in the construction of meaning and the emergence of field-level logics. In particular, we argue that imageries-of-practice, compared to verbal vocabularies, are just as well equipped to link locally resonating symbolic representations and globally diffusing practices, thus expressing both the material and ideational dimension of institutional logics in processes of translation. We find that visual rhetoric used in the Austrian discourse emphasizes the qualities of CSR as a bridging concept, and facilitates the mediation of inconsistencies in several ways: By translating abstract global ideas into concrete local knowledge, imageries-of-practice aid in mediating spatial oppositions; by linking the past, present, and future, they bridge time; by mediating between different institutional spheres and their divergent logics, they appease ideational oppositions and reduce institutional complexity; and, finally, by connecting questionable claims with representations of authenticity, they aid in overcoming credibility gaps.

This paper aims to propose a design method for attenuating stress waves pressure using soft matrix embedded with particles.

Based on the phononic crystal theory, the particle composed of hard core and soft coating can form a spring oscillator structure. When the frequency of the wave is close to the resonance frequency of the spring oscillator, it can cause the resonance of the particle and absorb a lot of energy. In this paper, the resonant phononic crystal with three phases, namely, matrix, particle core and coating, is computationally designed to effectively mitigate the stress wave with aperiodic waveform.

The relationship between the center frequency and width of the bandgap and the geometric and physical parameters of particle core are discussed in detail, and the trend of influence is analyzed and explained by a spring oscillator model. Increasing the radius of hard core could effectively enhance the bandgap width, thus enhancing the effect of stress wave attenuation. In addition, it is found that when the wave is in the bandgap, adding viscosity into the matrix will not further enhance the stress attenuation effect, but will make the stress attenuation effect of the material worse because of the competition between viscous dissipation mechanism and resonance mechanism.

This study will provide a reference for the design of stress wave protection materials with general stress waves.

This study proposes a design method for attenuating stress waves pressure using soft matrix embedded with particles.

The main purpose of this paper is to investigate the vibration isolation performance of a quasi-zero stiffness (QZS) metastructure by employing the band gap (BG) mechanism.

The metastructure QZS characteristic was investigated through static analysis by numerical simulation. Based on that, the BG mechanism is primarily used in this article to investigate the wave propagation characteristics of this structure. The model's dispersion relation is then examined using theoretical (perturbation method) and finite element techniques. The dynamic response of the finite-size systems and experimental analysis is used to confirm the vibration mitigation property under investigation. Finally, the model's ability to absorb energy was examined and contrasted with a traditional model.

The analytical analysis reveals the dispersion curve and the effect of the nonlinear parameter on the curve shifting. The dispersion curve in the finite element method (FEM) result depicts five complete BGs within the range of 0–1,000 Hz, and the BG width accounted for 67.4% of the frequency concerned (0–1,000 Hz). Eigenmodes of the dispersion curves were analyzed to investigate the BG formation mechanisms. The dependence of BG opening and closure on structure parameters was also studied. Finally, the energy absorption property of the QZS metastructure was evaluated by comparing it with a classical model. The QZS structure absorbs 4.08 J/Kg compared to the 3.69 J/Kg absorbed by the classical model, which reveals that the QZS demonstrates better energy absorption performance. Based on the BG mechanism, it is clear that this model is an excellent vibration isolator, and the study reveals the frequencies at which complete vibration mitigation is achieved. As a result, this model could be a promising candidate for vibration mitigation engineering structures and energy absorption.

The tough vibration issue, which is primarily experienced in mechanical equipment, will be resolved in this study. This study provides a precise understanding of the QZS metastructure's isolation of vibration, including the frequencies at which this isolation occurs.

With the development of the modern technology and aerospace industry, the noise pollution is remarkably affecting people’s daily life and has been become a serious issue. Therefore, it is the most important task to develop efficient sound attenuation barriers, especially for the low-frequency audible range. However, low-frequency sound attenuation is usually difficult to achieve for the constraints of the conventional mass-density law of sound transmission. The traditional acoustic materials are reasonably effective at high frequency range. This paper aims to discuss this issue.

Membrane-type local resonant acoustic metamaterial is an ideal low-frequency sound insulation material for its structure is simple and lightweight. In this paper, the finite element method is used to study the low-frequency sound insulation performances of the coupled-membrane type acoustic metamaterial (CMAM). It consists of two identical tensioned circular membranes with fixed boundary. The upper membrane is decorated by a rigid platelet attached to the center. The sublayer membrane is attached with two weights, a central rigid platelet and a concentric ring with inner radius e. The influences of the distribution and number of the attached mass, also asymmetric structure on the acoustic attenuation characteristics of the CMAM, are discussed.

In this paper, the acoustic performance of asymmetric coupled-membrane metamaterial structure is discussed. The influences of mass number, the symmetric and asymmetry structure on the sound insulation performance are analyzed. It is shown that increasing the number of mass attached on membrane, structure exhibits low-frequency and multi-frequency acoustic insulation phenomenon. Compared with the symmetrical structure, asymmetric structure shows the characteristics of lightweight and multi-frequency sound insulation, and the sound insulation performance can be tuned by adjusting the distribution mode and location of mass blocks.

Membrane-type local resonant acoustic metamaterial is an ideal low-frequency sound insulation material for its structure is simple and lightweight. How to effectively broaden the acoustic attenuation band at low frequency is still a problem. But most of researchers focus on symmetric structures. In this study, the asymmetric coupled-membrane acoustic metamaterial structure is examined. It is demonstrated that the asymmetric structure has better sound insulation performances than symmetric structure.

We examine the emergence of an organizational form, charter schools, in Oakland, California. We link field-level logics to organizational founding identities using topic modeling. We find corporate and community founding actors create distinct and consistent identities, whereas more peripheral founders indulge in more unique identity construction. We see the settlement of the form into a stable ecosystem with multiple identity codes rather than driving toward a single organizational identity. The variety of identities that emerge do not always map onto field-level logics. This has implications for the conditions under which organizational innovation and experimentation within a new form may develop.

The sociological and socio-legal literatures on social movements have identified three main types of “legal framing” in contemporary social movement discourse: collective rights framing, individual rights framing, and nationalistic legal framing. However, it is unclear from the current research how movement actors decide which of these framing strategies to use, under what circumstances, and to what effect. In this article, I offer a model for future empirical research on legal framing, which (1) distinguishes legal framing by its argumentative structure, ideological content, and remedy; and (2) analyzes how a social movement’s internal culture and institutional environment constrain the symbolic utility of particular legal frames and shape the movement’s legal framing strategy. I argue that the alternative approach offered here will help theorize how social movements strike a balance between the institutional pressure to reproduce dominant ideologies and the internal pressure to reform those ideologies. This perspective thus helps build socio-legal theory on the relationship between legal framing and social subordination, and on the conditions under which movements will be able to inflect legal language with insurgent social movement values.

The purpose of this paper is to explore power-resistance plays, or organisational change (OC) politics, from a discourse theory perspective to deepen our understanding of the political and emotional dimensions of these phenomena.

The paper deploys Laclauian concepts of hegemony, fantasmatic narrative and empty signifiers alongside a recently-developed logics of critical explanation approach in the case study of an English local authority formulating a project of integrated commissioning in response to austerity.

The paper demonstrates how OC politics are played out in multiple ways, from social and political negotiations over the meaning of commissioning to the refuelling of the authority’s fantasmatic narrative.

The paper’s key value is to illustrate how and why discourse theory can contribute, alongside other discursive frameworks, to the in-depth qualitative and political study of organisational issues such as change.