Structure-borne sound transmission between coupled plates

Abstract unavailable please refer to PDF

Modelling Bending Wave Transmission across Coupled Plate Systems Comprising Periodic Ribbed Plates in the Low-, Mid-, and High-Frequency Ranges Using Forms of Statistical Energy Analysis

Prediction of bending wave transmission across systems of coupled plates which incorporate periodic ribbed plates is considered using Statistical Energy Analysis (SEA) in the low- and mid-frequency ranges and Advanced SEA (ASEA) in the high-frequency range. This paper investigates the crossover from prediction with SEA to ASEA through comparison with Finite Element Methods. Results from L-junctions confirm that this crossover occurs near the frequency band containing the fundamental bending mode of the individual bays on the ribbed plate when ribs are parallel to the junction line. Below this frequency band, SEA models treating each periodic ribbed plate as a single subsystem were shown to be appropriate. Above this frequency band, large reductions occur in the vibration level when propagation takes place across successive bays on ribbed plates when the ribs are parallel to the junction. This is due to spatial filtering; hence it is necessary to use ASEA which can incorporate indirect coupling associated with this transmission mechanism. A system of three coupled plates was also modelled which introduced flanking transmission. The results show that a wide frequency range can be covered by using both SEA and ASEA for systems of coupled plates where some or all of the plates are periodic ribbed plates

Prediction of airborne sound transmission across a timber-concrete composite floor using Statistical Energy Analysis

This paper concerns the development and experimental validation of prediction models using Statistical Energy Analysis (SEA) to calculate the airborne sound insulation of a timber–concrete composite floor. The complexity in modelling this floor is due to it having (1) a multilayer upper plate formed from concrete and Oriented Strand Board (OSB), (2) multiple types of rigid connector between the upper plate and the timber joists and (3) a resiliently suspended ceiling. A six-subsystem model treats the concrete–OSB plate as a single subsystem and three different five-subsystem models treat the combination of concrete, OSB and timber joists as a single orthotropic plate subsystem. For the orthotropic plate it is suggested that bending stiffnesses predicted using the theories of Huffington and Troitsky provide a more suitable and flexible approach than that of Kimura and Inoue. All SEA models are able to predict the weighted sound reduction index to within 2 dB of the measurement. The average difference (magnitude) between measurements and predictions in one-third octave bands is up to 4 dB. These results confirm that SEA can be used to model direct transmission across relatively complex floor constructions. However, this requires the inclusion of measured data in the SEA model, namely the dynamic stiffness of the resilient isolators and the cavity reverberation time

What is the most appropriate treatment for chronic rhinosinusitis?

Chronic rhinosinusitis (CRS) is a common, treatable disease that affects approximately 11% of British adults. It places an enormous burden on patients, with significant detriment to their quality of life, and the health service as it consumes vast numbers of both primary and secondary care resources. However, there is considerable variability in treatment strategies and prescribing practices. This review summarises the key recommendations from landmark guidelines in the treatment of CRS and critically appraises the evidence for treatment

Comparison of high-intensity sound and mechanical vibration for cleaning porous titanium cylinders fabricated using selective laser melting

Orthopedic components, such as the acetabular cup in total hip joint replacement, can be fabricated using porous metals, such as titanium, and a number of processes, such as selective laser melting. The issue of how to effectively remove loose powder from the pores (residual powder) of such components has not been addressed in the literature. In this work, we investigated the feasibility of two processes, acoustic cleaning using high‐intensity sound inside acoustic horns and mechanical vibration, to remove residual titanium powder from selective laser melting‐fabricated cylinders. With acoustic cleaning, the amount of residual powder removed was not influenced by either the fundamental frequency of the horn used (75 vs. 230 Hz) or, for a given horn, the number of soundings (between 1 and 20). With mechanical vibration, the amount of residual powder removed was not influenced by the application time (10 vs. 20 s). Acoustic cleaning was found to be more reliable and effective in removal of residual powder than cleaning with mechanical vibration. It is concluded that acoustic cleaning using high‐intensity sound has significant potential for use in the final preparation stages of porous metal orthopedic components. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 117–123, 2017

Electrical and behavioral courtship displays in the mormyrid fish Brienomyrus brachyistius

Mormyrid electric fish rely on the waveform of their electric organ discharges (EODs) for communicating species, sex, and social status, while they use the sequences of pulse intervals (SPIs) for communicating rapidly changing behavioral states and motivation. Little is known of electric signaling during courtship behavior because of two major difficulties: (1) the fish are not easily bred in captivity and (2) there is no reliable means of separating electric signals from several individuals in natural communication settings. Through simulating artificial rain conditions, we have successfully induced courtship and succeeded in breeding a mormyrid electric fish (Brienomyrus brachyistius) in the laboratory. We have also developed a system of video recording and editing combined with cross correlation analysis to precisely record and view behavior and separate EODs from two individuals in non-breeding and breeding contexts. Knowing the electrical and motor patterns during courtship allows for further exploration of topics such as mate choice and neural basis of pattern generation in these fish. Here we describe nine common motor displays and 11 SPIs. Analysis of frequency of occurrences suggests that some SPI patterns are sex and season specific. We also observed electrical duetting called `rasp matching\u27 during courtship signaling among pairs; males and females exchange `rasps\u27 and `bursts\u27, respectively, in alternation. Our study employs new techniques to separate and document SPIs in the context of courtship. We show that some SPIs correlate with specific behavioral acts around the time of spawning

Expanding Farm-Fresh Direct-Marketing Opportunities in the 21st Century

Direct-marketing and agri-tourism businesses have recently begun to promote their businesses using stand-alone websites allowing them to tap into a larger customer base. This has created a need for direct farm markets to identify the products and services consumers are demanding from online sources. This project proposes to conduct an online survey of consumer preferences in buying direct from the farmer vs. the types of products consumers are seeking on the Internet. Our hypothesis is that the use of stand-alone web sites limit the number of consumers that farm marketers are reaching due to the time and expense involved in keeping them updated. This online survey will collect information useful in describing how farm marketers can use the Internet to increase their customer base and individual profits.Marketing,

The Shape, Multiplicity, and Evolution of Superclusters in LambdaCDM Cosmology

We determine the shape, multiplicity, size, and radial structure of superclusters in the LambdaCDM concordance cosmology from z = 0 to z = 2. Superclusters are defined as clusters of clusters in our large-scale cosmological simulation. We find that superclusters are triaxial in shape; many have flattened since early times to become nearly two-dimensional structures at present, with a small fraction of filamentary systems. The size and multiplicity functions are presented at different redshifts. Supercluster sizes extend to scales of ~ 100 - 200 Mpc/h. The supercluster multiplicity (richness) increases linearly with supercluster size. The density profile in superclusters is approximately isothermal (~ R^{-2}) and steepens on larger scales. These results can be used as a new test of the current cosmology when compared with upcoming observations of large-scale surveys.Comment: 33 pages, 15 figures, accepted to ApJ; minor content changes, some figures removed to shorten pape