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The air dissipation, mainly due to the boundary effect at interior walls of impedance tubes, is noteworthy for normal incidence measurements of acoustic materials using the transfer function method. This work proposes a transfer function model-based Bayesian approach to estimate the dissipation factors. Other parameters, such as the sound speed and the microphone positions, are also critical, therefore, estimated as well, along with the dissipation. The measurement of the empty impedance tube with a rigid termination applies the two-microphone transfer function method. A hypothetical air layer assumed in front of the rigid backing enables the numerical comparison between the air layer’s theoretical and experimental transfer function values. Experimental results incorporating the estimated dissipation coefficient validate the accuracy of the proposed approach. Furthermore, the estimated parameters are incorporated into further evaluations of material properties using the transfer function method, which effectively reduces the residual absorption error of the impedance tube measurement.

Conventional chamber-based methods of random incidence absorbing coefficients overlook the non-diffused sound field in the room acoustics, which decreases accuracy and may even lead to conflicting results. This work applies the diffusion equation model to room-acoustic simulations of standardized reverberation chambers. The simulations can more efficiently capture the chamber's non-diffuse sound field and energy flows than wave-based simulation models. The diffusion equation represents the governing equation of reverberant sound energy densities within the reverberation chamber which is solved using the finite-difference time-domain method. Its computational efficiency of diffusion equation-based modeling lies in a highly sparse domain meshing condition dictated by the mean-free path length rather than wavelengths and still derives a wideband simulation result. This work also dedicates the effort to reexamine the meshing condition, particularly for standardized finite sizes of sound absorbers for measurements of random incidence absorption coefficients. By comparing the outcomes of simulations with measurement data, an a posteriori absorption coefficient is inversely estimated involving Bayesian parameter estimation.

The Graduate Program in Architectural Acoustics has been constantly advanced from its inception in 1998 with an ambitious mission of educating future experts and leaders in architectural acoustics, due to the rapid pace of change in the fields of architectural-, physical-, and psycho-acoustics, and noise-control engineering. Since years the program’s pedagogy using “STEM” (science, technology, engineering, and mathematics) methods has been proven to be effective and productive, including intensive, integrative hands-on experimental components that integrate architectural acoustics theory and practice. The graduate program has recruited graduate students from a variety of disciplines including individuals with B.S., B.Arch., or B.A. degrees in Mathematics, Physics, Engineering, Architecture, Electronic Media, Sound Recording, Music and related fields. Graduate students under this pedagogy and research environment have been succeed in the rapidly changing field. RPI’s Graduate Program in Architectural Acoustics has since graduated more than 120 graduates with both M.S. and Ph.D. degrees. Under the guidance of the faculty members they have also actively contributed to the program’s research in architectural acoustics, communication acoustics, psycho-acoustics, signal processing in acoustics as well as our scientific exploration at the intersection of cutting edge research and traditional architecture/music culture. This paper illuminates the evolution and growth of the Graduate Program.

This showcase article presents a 50-year-old, 1500-km-long irrigation canal in China as an exemplary case of socio-ecological practice. With a focus on its genesis, the article is the first of a mini-series on one of the best kept secrets in the history of socio-ecological practice.

Research consistently shows that higher-education participation has positive impacts on individual outcomes. However, few studies explicitly consider differences in these impacts by socio-economic background (SEB), and those which do fail to examine graduate trajectories over the long run, non-labor outcomes and relative returns. We address these knowledge gaps by investigating the short- and long-term socio-economic trajectories of Australian university graduates from advantaged and disadvantaged backgrounds across multiple domains. We use high-quality longitudinal data from two sources: the Australian Longitudinal Census Dataset and the Household, Income and Labour Dynamics in Australia Survey. Low-SEB graduates experienced short-term post-graduation disadvantage in employment and occupational status, but not wages. They also experienced lower job and financial security up to 5 years post-graduation. Despite this, low-SEB graduates benefited more from higher education in relative terms—that is, university education improves the situation of low-SEB individuals to a greater extent than it does for high-SEB individuals.

In two articles recently published in this journal, Wei-Ning Xiang presents four instances of Ian McHarg’s effective, time-honored socio-ecological practice research and raises the question of why he was so successful in discovering and articulating truth in these exemplary cases. In this knowledge II (2) a pragmatic way of knowing; (3) an ethical belief in human beings’ enlightened self-interest; and (4) a classic style of writing.

In this showcase article, the author presents three exemplary instances of Ian McHarg’s effective, time-honored socio-ecological practice research. Each case is powered by an insightful idea he discovered in practice and articulated for practice. These are, respectively, the idea “to green the earth,” the intrinsic “unsuitability for urbanization,” and “a profoundly simple concept” for building ecological resilience. Together, these examples make a compelling case for the statement that “McHarg had it right” many times.

Binaural auralization through proper room-acoustic simulation can produce a realistic listening experience as if the listener were sitting in a room with spatial perception, including enveloping reverberance. Based on analysis of experimentally measured binaural room-acoustic data, this paper discusses an approach to creating artificial but natural-sounding reverberation for binaural rendering that can be employed in simulating such an environment in an efficient way. Approaches to adjusting the spaciousness of enveloping reverberance within the context of artificially generated reverberation are investigated via hearing tests. This paper exploits the excellent pseudorandom properties of maximum-length sequences to generate deterministic and controllable decorrelations between binaural channels for artificial reverberation for room-acoustic simulations with high computational efficiency. To achieve natural-sounding enveloping reverberance in an enclosed space, and thereby an immersive environment, the shapes of both the reverberation energy decays and the spatial characteristics are found to be decisive. This paper discusses systematic hearing test results that support the mentioned finding.

In this communication, the author defines ecopracticology as a legitimate field of scholarly inquiry, discusses its theoretical independence and interdependence, introduces Socio-Ecological Practice Research (SEPR) as its home journal, and pays tribute to those who contributed to the field’s development. In compliance with journal’s requirements for the article type Communication, presentations are concise; footnotes are used as needed to compensate brevity.

Reversing ecological degradation is critical for survival of many species but will not occur without a transformational reduction in humanity’s environmental impact. Ecological civilization is a way of approaching social and ecological reform and represents a new standard of human existence that may be sustainable well into the future. However, how to achieve ecological civilization still remains a question. Landscape sustainability science, with its theoretical basis in sustainability science and landscape ecology, offers a decisive path for achieving an ecological civilization. Three concepts integral to landscape ecology will be essential for contributing to an ecological civilization: (1) linking landscape patterns with biodiversity and ecosystem processes/function across scales, (2) measuring connectivity and flows across spatially heterogeneous systems, and (3) a systems understanding of the linkages between disturbance, resilience, and recovery. Achieving an ecological civilization is within the scope of human capability, but it will require a fundamental shift in world view and cooperation amongst all actors in the human race. A key place to start is with landscapes. This editorial provides perspectives from landscape ecology and landscape sustainability science for achieving this goal

Sound speed, microphone positions, and tube wall dissipation are critical parameters for absorption and impedance measurements using the transfer-function method in an impedance tube. This work applies a Bayesian method, based on a reflection coefficient model of an air layer and a boundary layer dissipation model, to estimate the values of these parameters for tube measurements. This estimation is based on experimental measurements obtained in the empty impedance tube with a rigid termination. Analysis results demonstrate that this method is able to accurately estimate the dissipation coefficient, the sound speed, and the microphone positions for highly accurate tube measurements.

Acoustic surface admittance/impedance at domain boundaries is essential for wave-based acoustic simulations. This work applies two levels of Bayesian inference to estimate the order and the parameter values of the multipole admittance model. The frequency-dependent acoustic admittance is experimentally measured. Incorporating the maximum entropy strategy, the unified Bayesian framework is applied to the multipole approximation. Analysis results demonstrate that multipole model-based Bayesian inference is well suited to estimating the arbitrary frequency-dependent boundary condition within a wave-based simulation framework.

Scaffolds suitable for use in food products are crucial components for the production of cultured meat. Here, wheat glutenin, an inexpensive and abundant plant-based protein, was used to develop 3D porous scaffolds for cultured meat applications. A physical cross-linking method based on water annealing was developed for the fabrication of porous glutenin sponges and fibrous aligned scaffolds. The pore sizes ranged from 50 to 250 μm, with compressive modulus ranges from 0.5 to 1.9 kPa, depending on the percentage of glutenin (2%-5%) used in the process. The sponges were stable in PBS with refrigeration for at least six months after water annealing. The glutenin scaffolds supported the proliferation and differentiation of C2C12 mouse skeletal myoblasts and bovine satellite cells (BSCs) without the need to add specific cell adhesive proteins or other coatings. The low cost and food safe production process avoided the use of toxic cross-linkers and animal-derived extracellular matrix (ECM) coatings, suggesting that this as approach is a promising system for scaffolds useful in cultivated meat applications.

BACKGROUND Plexiform fibromyxoma is a rare, special type of mesenchymal tumor. The most common presenting symptoms are anemia, hematemesis, and hematochezia, without sex or age predilection. The reported cases have mainly occurred in the gastric antrum and pylorus region, with some cases in the duodenum. CASE SUMMARY We report here a case of plexiform fibromyxoma in the upper segment of the jejunum, which was continuously followed up for 3 years after surgical removal. Plexiform fibromyxoma showed multinodular or plexiform growth. The cells in the tumor node were spindle-shaped but few in number and mitotic figures. Small blood vessels and mucous matrix were found among the tumor cells. Immunohistochemistry revealed that the plexiform fibromyxoma cells were positive for smooth muscle actin, focally positive for CD10, and negative for cytokeratin, CD117, DOG-1 (discovered on GIST-1) desmin, S-100, epithelial membrane antigen, and CD34. Ki-67 labeling index was < 5%. Plexiform fibromyxoma showed benign biological behavior. After 3 years of consecutive postoperative follow-up, no obvious signs of metastasis or recurrence were found by imaging examination. CONCLUSION Plexiform fibromyxoma is a rare type of mesenchymal tumor. The diagnosis mainly depends on pathological examination, and it should be distinguished from other gastrointestinal mesenchymal tumors.

With an increasing acknowledgement of climate variability, the important role of resilience in achieving healthy urban ecosystems has also been discussed by the academics recently. The literature however shows ambiguity about the characteristics of urban resilience, while substantive progress has been made in the practice of resilience building in urban communities. To bridge the gap between theory and practices, this paper dedicate to answer the question: What are the typical characteristics of resilient urban communities? Using the research method of case study, the paper screens and analyzes four exemplary cases of resilient urban communities from around the world, articulating the specific resilient strategies and their core resilient concept of each case. Finally, eight characteristics in four performance dimensions are distilled and explained. The identification of the characteristics provides a scenario of resilient urban community, and it also gives the direction for fostering the urban community resilience. Keywords: Resilience, Characteristics of resilience, Case study, Resilient urban community

In many acoustical applications, porous materials may be stratified or physically anisotropic along their depth direction. In order to better understand the sound absorbing mechanisms of these porous media, the depth-dependent anisotropy can be approximated as a multilayer combination of finite-thickness porous materials with each layer being considered as isotropic. The uniqueness of this work is that it applies Bayesian probabilistic inference to determine the number of constituent layers in a multilayer porous specimen and macroscopic properties of their pores. This is achieved through measurement of the acoustic surface impedance and subsequent transfer-matrix analysis based on a valid theoretical model for the acoustical properties of porous media. The number of layers considered in the transfer-matrix analysis is varied, and Bayesian model selection is applied to identify individual layers present in the porous specimen and infer the parameters of their microstructure. Nested sampling is employed in this process to solve the computationally intensive inversion problem.

Amaranthus is a complex taxon with economic importance as well as harmful weeds. We studied the genetic variation and structure of the chloroplast genomes of 22 samples from 17 species of three subgenera. It was found that the length of the chloroplast genome of Amaranthus varied from 149,949 bp of A. polygonoides to 150,757 bp of A. albus. The frequencies of SNPs and InDels in chloroplast genomes were 1.79 % and 2.86 %, and the variation mainly occurred in the non-coding regions. The longest InDel was 387 bp, which occurred on ycf2, followed by 384 bp InDel on psbM-trnD. Two InDels in ndhE-I on the SSC make the three subgenera clearly distinguished. In LSC, SSC and IRs regions, there were four 30 bp forward and reverse repeats, and the repeats in SSC and LSC were in nearly opposite positions in circular genome structure, and almost divided the circular genome into symmetrical structures. In the topological tree constructed by chloroplast genome, species in subgen. Amaranthus and subgen. Acnida form monophyletic branches separately and cluster together. A. albus, A. blitoides and A. polygonoides were separated from subgen. Albersia, and the rest of subgen. Albersia were clustered into a monophyletic branch. The rpoC2, ycf1, ndhF-rpl32 were good at distinguishing most amaranths. The trnk-UUU-atpF, trnT-UGU-atpB, psbE-clpP, rpl14-rps19, and ndhF-D can distinguish several similar species. In general, the chloroplast genome is of certain value for the identification of the similar species of Amaranthus, which provides more evidence for clarifying the phylogenetic relationships within the genus.

Antibacterial agents with broad-spectrum antibacterial properties have always been in large demand. Lysozyme, a common and inexpensive protein, is widely used in food safety and biomedical applications for antibacterial purposes. However, many pathogens are lysozyme-resistant or insensitive. In this research, we investigated the antibacterial activities and mechanism of oligomers and amyloid fibrils formed from hen egg-white lysozyme (HEWL) against

When physical or other quantities vary in a specific way as a function of time, we say that they oscillate. A common, very broad definition of oscillation is as follows.

The wave equation as derived in Section 7.1 and used so far in this book, is valid for sound propagation in lossless media. The Helmholtz form of this equation is

The wave equations derived in the preceding chapter allow for calculation of arbitrary sound fields with any possible, physically meaningful boundary conditions. We had restricted ourselves to one-dimensional waves so far. These can, for instance, be observed in tubes with a diameter being small compared to the wavelength, that is d ≪ λ. This condition guarantees that no other waveforms than axial ones can propagate in the tube. One-dimensional propagation also means that all wave planes perpendicular to the axial direction are planes of constant phase.

The chapter deals with the wave equation in the spherical coordinate system. The wave equation as derived in Chap. 7 theoretically covers all possible sound fields in idealized fluids. However, the task of computing specific sound fields requires solutions of the wave equation for the particular boundary conditions in each case. In this chapter, we discuss some exemplary cases that can be solved analytically and are often sufficient to understand the structure of a problem, namely, the sound fields of spherical sound sources of 0th, 1st, and higher-order. Furthermore, the sound fields of line arrays of monopoles (0th-order spherical sources) are discussed in detail. It is shown that the directional characteristics of such arrays can be computed by Fourier transform of the spatial distribution of monopoles and their strengths.

Despite mounting evidence that university participation enhances labour-market prospects, there are growing concerns about unequal returns to university for graduates from advantaged and disadvantaged social backgrounds. The available evidence-base, however, suffers from significant shortcomings that challenge the validity of these findings—including small sample sizes, cross-sectional designs, and self-reported measures of labour-market performance. In this study, we overcome these methodological limitations by leveraging large-scale linked administrative data covering the full population of individuals graduating from Australian universities over the 2005-2011 period (n=3,107,085 annual observations and 565,318 graduates). Capitalising on this unique and powerful dataset, we examine differences in the labour-market trajectories of graduates from multiple social backgrounds (based on socio-economic status, ethnicity, migration, location, and disability) over a 10-year observation window. We track both their employment earnings and the amount of unemployment benefits that they received. Our findings reveal higher returns to university education over the first 10 years post-graduation amongst graduates from advantaged social backgrounds compared to their peers from more disadvantaged social backgrounds. However, there was substantial heterogeneity in graduates’ earnings and unemployment-benefit receipt both across groups and over time. Of the five groups considered, graduates with a disability and from non-English speaking backgrounds experienced the worst outcomes, whereas graduates from low socio-economic status backgrounds and regional, rural and remote areas fared comparatively well. Indigenous graduates experienced inconsistent outcomes that changed markedly with time since graduation. These findings bear important implications for policy and practice in relation to both higher education and the labour market.

During the discussion of simple mechanic and acoustic oscillators in Chapter 2, readers with some electrical engineering experience may have realized that many mathematical formulae are similar to those that appear when dealing with electric oscillators. There is a general isomorphism of the equations in mechanic, acoustic and electric networks that can be exploited for describing mechanic and acoustic networks via analogous electric ones. Formulation in electrical coordinates is often to the advantage of those who are familiar with the theory of electric networks since analysis and synthesis methods from network theory can be easily and figuratively applied.

In electric-field transducers mechanic forces are caused by electric fields or, in the reverse effect, electric polarization is influenced by mechanic forces. Even more than magnetic-field transducers, electric-field transducers exist in a wide variety of forms and shapes. There are transducers that are intrinsically linear and others that naturally have a quadratic force law and must be linearized. There are also irreversible controlled couplers. In this chapter we concentrate on the basic principles of electric-field transducers and discuss some illustrative examples.

Each of the preceding Chapters 1-14 includes a collection of exercise problems. The current chapter proposes detailed approaches and solutions to all of them and, consequently, more in-depth treatment of the mathematical foundations of the contents presented in the main body of this book.

This work focuses on design of multilayer micro-perforated/slit panels (MPP/MSP) to create high sound absorption over a wide bandwidth. Theoretically micro-slit panels are equivalent to micro-perforated panels and can similarly achieve high absorption coefficients. Yet, fabrication of microslit panels is much easier. Using transparent panels, they are visually more transparent than MPPs since the MSPs yield more unobstructed panel for a given perforation rate. However, MPP and MSP absorbers in single setting are frequency limited to a bandwidth often not sufficient in applications. Stacking multilayered MPP/MSP panels, a high absorption becomes achievable in a wider bandwidth. Using existing single-panel MPP/MSP models, a transfer matrix method is suitable for cascading multilayers to predict overall absorption performance. This prediction model is applied to a Bayesian framework in coping with design challenges arising from designing MPP/MSP parameters for multiple layers that fulfills a given design scheme. The Bayesian design reported here rapidly converges to a parsimonious number of layers with optimized parameters for each layer, and the overall absorption is able to fulfill the design scheme for minimally possible fabrication complexity. In addition, performing iterative Bayesian analysis during the panel fabrication and experimental validation guides corrections due to fabrication inaccuracies.

Thin panels of viscoelastic materials have been shown to have tremendous sound transmission loss enhancement characteristics when implemented in sandwiched gypsum wall panels. However, it is challenging to obtain reliable dynamic mechanical properties of these materials across relevant building acoustics frequencies. To better understand the dynamic mechanical properties of these materials, a methodology employing bending wave characterization is discussed. Relying on inversion processes from the measured panel velocities, this methodology yields loss factors, complex elastic moduli and phase speeds. The dispersive nature of these bending wave phenomena in viscoelastic panels opens a unique set of challenges for reliable dynamic mechanical property characterization. This paper discusses these challenges as wells as an approach to mitigate these effects and improve measurement reliability.

Room-acoustic simulations for sound wave propagation require significant knowledge of the boundary conditions for the room boundary surface. This work presents the application of model-based Bayesian inference on the surface admittance estimation problem. First, this work deals with selecting the multipole admittance model through the higher level of inference, Bayesian model selection. And the parameters of the chosen multipole admittance model are estimated through the first (lower) level of inference, Bayesian parameter estimation. This work focuses on the approximation of the surface admittance as a function of frequency given a set of acoustic admittance. This frequency-dependent admittance is deduced either from the experimental measurements of a porous material or numerical predictions in order to demonstrate wave-based boundary conditions to incorporate arbitrary admittance functions with frequency ranges under consideration. According to the analytical results and numerical verifications conducted in this work, Bayesian inference based on the multipole model is well-suited for the estimation of the frequency-dependent boundary conditions within a wave-based simulation framework.

A spherical microphone array is used to detect and localize sound sources in terms of model-based machine learning (ML). In this application, it is crucial to establish parametric models to distinguish background sound environment from presence of sound sources. In the presence of sound sources, the parameter models are also used to localize an unknown number of potentially multiple sound sources. In this work, a model-based Bayesian learning framework is presented for localizing an unknown number of sound sources. Among them, a no-source scenario needs to be accounted for. The model-based machine learning applies the model comparison between the no-source model and the one-source model for sound source detection. After detecting sound sources, the machine learning needs to involve sound source enumeration and localization in order to correctly localize potential multiple sound sources. Specifically, sound environment is analyzed using Bayesian model comparison of two different models accounting for absence and presence of the sound sources for source detection. Upon a positive detection, potentially multiple source models are involved to analyze direction of arrivals (DoAs) for far-field and to localize sound sources for near-field including source distances, amplitudes, and DoAs using Bayesian model selection and parameter estimation.

The sound field in reverberation chambers used for measuring sound absorption coefficients is usually non-diffuse, leading to inaccuracies and disagreements in the results. In this paper, a diffusion equation model is applied to simulating reverberation chambers in order to obtain reverberant energy distributions and sound energy flows of the chamber under investigation in a more efficient way than wave-based simulation models. The computational efficiency of the diffusion equation lies in the fact that the meshing condition of the simulation domain is dictated by the room's mean-free path length (MFPL). Further investigation shows one-twelfth of MFPL as the meshing condition is considered practically sufficient for obtaining random incidence absorption coefficient of standardized sample sizes. With the computational efficiency given by a meshing of up to twelfth MFPL, an inversion calculation of random incident absorption coefficients of highly absorptive materials is possible with a mixed boundary condition [Jing and Xiang, JASA 123, pp. 145–153 (2008)]. Based on analysis of both chamber-based measurements and simulated data, ways to scrutinize measurement results of absorptive materials are investigated.