Spring Reverberation: A Physical Perspective

Spring-based artificial reverberation was one of the earliest attempts at compact replication of room-like reverberation for studio use. The popularity and unique sound of this effect have given it a status and desirability apart from its original use. Standard methods for modeling analog audio effects are not well suited to modeling spring reverberation, due to the complex and dispersive nature of its mechanical vibration. Therefore, new methods must be examined. A typical impulse responses of a spring used for reverberation is examined, and important perceptual parameters identified. Mathematical models of spring vibration are considered, with the purpose of drawing conclusions relevant to their application in an audio environment. These models are used to produce new results relevant to the design of digital systems for the emulation of spring reverberation units. The numerical solution of these models via the finite difference method is considered. A set of measurements of two typical spring reverberation units are presented. 1

Modelling Methods for the Highly Dispersive Slinky Spring: A Novel Musical Toy

ABSTRACT The 'Slinky' spring is a popular and beloved toy for many children. Like its smaller relatives, used in spring reverberation units, it can produce interesting sonic behaviors. We explore the behavior of the 'Slinky' spring via measurement, and discover that its sonic characteristics are notably different to those of smaller springs. We discuss methods of modeling the behavior of a Slinky via the use of finite-difference techniques and digital waveguides. We then apply these models in different structures to build a number of interesting tools for computer-based music production

Evaluating the Potential of Container-Based Sanitation

In the face of urbanization, alternative approaches are needed to deliver adequate and inclusive sanitation services across the full sanitation service chain. Container-based sanitation (CBS) consists of an end-to-end service—that is, one provided along the whole sanitation service chain—that collects excreta hygienically from toilets designed with sealable, removable containers and strives to ensure that the excreta is safely treated, disposed of, and reused. This report builds on four case studies (SOIL – Haiti, x-runner – Peru, Clean Team – Ghana, Sanergy – Kenya) to assess the role CBS can play in a portfolio of solutions for citywide inclusive sanitation (CWIS) services. The authors conclude that CBS approaches should be part of the CWIS portfolio of solutions, especially for poor urban populations for whom alternative on-site or sewer-based sanitation services might not be appropriate. Customer satisfaction with existing services is high and services provided by existing CBS providers are considered safe but have some areas for improvement. While the proportion of total CBS service costs covered by revenues is still small, CBS services are considered to be priced similarly to the main sanitation alternatives in their service areas. Recommendations include adopting a conducive policy and regulatory environment and exploring ways to ensure that CBS services are sustainably financed. The report also identifies areas for further analysis

Southeast Asia Primary Learning Metrics (SEA-PLM) : Global Citizenship Domain Assessment Framework

This assessment framework forms part of the Southeast Asia Primary Learning Metrics (SEAPLM) assessment program and outlines an approach to assessing global citizenship. The purpose of this assessment framework is to articulate the basic structure of the global citizenship domain as part of SEA-PLM. It provides a description of the constructs to be measured. It also outlines the design and content of the measurement instruments and describes how measures generated by those instruments relate to the constructs. It combines theory and practice to describe “both the ‘what’ and the ‘how’” (Jago, 2009, p. 1) of the SEA-PLM assessment of global citizenship. Global citizenship education (GCED) has emerged as a high priority across the globe to address the learning needs of an increasingly globalised world. Whilst GCED is a new term, it is based and builds upon associated fields, such as ‘peace education,’ ‘moral’ or ‘social education,’ and ‘civics and citizenship education’

Are inhalers with spacers better than nebulizers for children with asthma?

Metered-dose inhalers with a spacer (MDI/S) are as good as, or better than, nebulizers for children with asthma. This is based on numerous randomized controlled trials that compared outcomes such as hospital admission rates, asthma severity scores, and pulmonary function scores (strength of recommendation: A, based on consistent randomized controlled trials and meta-analysis)

The synoptic-dynamics of summertime heatwaves in the Sydney area (Australia)

Motivated by the record-breaking heatwaves of early 2017, the synoptic structure and evolution of summer (December–February) heatwaves in the Sydney area is investigated through composite and trajectory analyses. In the upper troposphere, the main features of the composite structure are an isolated upper-tropospheric anticyclonic potential vorticity (PV) anomaly to the south-east of Australia and cyclonic anomalies to the east and south. Back trajectories starting from within the upper-tropospheric anticyclonic PV anomaly on the first day of the heatwave fall into two groups: those that are diabatically cooled in the final 72 h and those that are diabatically heated. Those that are cooled come predominantly from the upstreammiddle troposphere over the Indian Ocean. The change in the potential temperature of these parcels is less than 3K, and so their motion is effectively adiabatic. In contrast, those parcels that are heated in the final 72 h are drawn predominantly from the lower half of the troposphere over the south-western part of the continent. As they ascended, their potential temperature increases by 10K in the mean due to latent heating. At low-levels, the main features of the composite are an anticyclone centred in the Tasman Sea, a broad low over the Southern Ocean and associated anomalous warmnorthwesterlies over the Sydney area. Five days prior to the heatwave, air parcels that become part of the near surface air mass are located predominantly offshore to the east and south of the continent. The anomalously high surface temperatures can be explained by adiabatic compression and surface sensible heating. For the next 48 h, the air parcels subside and their potential temperature changes little, whereas their temperature increases by around 15Kthrough adiabatic compression. In the final 72 h, as the parcels approach the surface and are entrained into the boundary layer, the potential temperature and temperature both increase by 5K, presumably through surface sensible heating. The record-breaking heatwaves of January and February 2017 are found to be very representative of previous heatwaves in the Sydney area, and in the mean they are synoptically very similar to heatwaves in Victoria, although dynamically there are differences

Antiderivative antialiasing for memoryless nonlinearities

Aliasing is a commonly encountered problem in audio signal processing, particularly when memoryless nonlinearities are simulated in discrete time. A conventional remedy is to operate at an oversampled rate. A new aliasing reduction method is proposed here for discrete-time memoryless nonlinearities, which is suitable for operation at reduced oversampling rates. The method employs higher order antiderivatives of the nonlinear function used. The first-order form of the new method is equivalent to a technique proposed recently by Parker et al. Higher order extensions offer considerable improvement over the first antiderivative method, in terms of the signal-to-noise ratio. The proposed methods can be implemented with fewer operations than oversampling and are applicable to discrete-time modeling of a wide range of nonlinear analog systems.Peer reviewe