Steady-state modeling of nutrient transformations in activated sludge treatment of pulp and paper wastewater

Wastewater treatment in the pulp and paper industry -- Activated sludge treatment -- Carbon & nutrient transformation mechanisms -- Data measurement, collection & processing -- Modelling : activated sludge models (ASM) -- Case study background : site & process -- Gaps in the body of knowledge, objectives hypothesis -- Wastewater Characterisation -- Mass Balance -- Modelling -- Errors Analysis -- Sensitivity Analysis -- Equivalent modelling nomenclature

Sound as Knowledge: A Dialogue with Samson Young

Dialogue between Samson Young and Lucy Cotter, exploring sound as a multi-faceted medium of artistic research

Writing as Experiment: A Dialogue with Sher Doruff

Dialogue between Sher Doruff and Lucy Cotter, exploring the potential of artistic writing to open experimental new forms of enquiry

Beyond Language: A Dialogue with Falke Pisano

Dialogue between Falke Pisano and Lucy Cotter, reflecting on ways in which artistic research exceeds the limits of linguistic thinking

Research as Play: A Dialogue with Ryan Gander

Dialogue between Ryan Gander and Lucy Cotter, exploring art as a form of visual thinking and playful material investigation

Becoming the Archive: A Dialogue with Euridice Kala

Dialogue between Euridice Kala and Lucy Cotter, exploring the potential of artistic research to form other archives

On the rate of convergence of the Hamiltonian particle-mesh method

The Hamiltonian Particle-Mesh (HPM) method is a particle-in-cell method for compressible fluid flow with Hamiltonian structure. We present a numer- ical short-time study of the rate of convergence of HPM in terms of its three main governing parameters. We find that the rate of convergence is much better than the best available theoretical estimates. Our results indicate that HPM performs best when the number of particles is on the order of the number of grid cells, the HPM global smoothing kernel has fast decay in Fourier space, and the HPM local interpolation kernel is a cubic spline

Bureaucracy as a Lens for Analyzing and Designing Algorithmic Systems

Scholarship on algorithms has drawn on the analogy between algorithmic systems and bureaucracies to diagnose shortcomings in algorithmic decision-making. We extend the analogy further by drawing on Michel Crozier’s theory of bureaucratic organizations to analyze the relationship between algorithmic and human decision-making power. We present algorithms as analogous to impartial bureaucratic rules for controlling action, and argue that discretionary decision-making power in algorithmic systems accumulates at locations where uncertainty about the operation of algorithms persists. This key point of our essay connects with Alkhatib and Bernstein’s theory of ’street-level algorithms’, and highlights that the role of human discretion in algorithmic systems is to accommodate uncertain situations which inflexible algorithms cannot handle. We conclude by discussing how the analysis and design of algorithmic systems could seek to identify and cultivate important sources of uncertainty, to enable the human discretionary work that enhances systemic resilience in the face of algorithmic errors.Peer reviewe

Inshore and offshore marine migration pathways of Atlantic salmon post-smolts from multiple rivers in Scotland, England, Northern Ireland and Ireland

The migratory behavior of Atlantic salmon (Salmo salar) post-smolts in coastal waters is poorly understood. In this collaborative study, 1914 smolts, from 25 rivers, in four countries were tagged with acoustic transmitters during a single seasonal migration. In total, 1105 post-smolts entered the marine study areas and 438 (39.6%) were detected on a network of 414 marine acoustic receivers and an autonomous underwater vehicle. Migration pathways (defined as the shortest distance between two detections) of up to 575 km and over 100 days at sea were described for all 25 populations. Post-smolts from different rivers, as well as individuals from the same river, used different pathways in coastal waters. Although difficult to generalize to all rivers, at least during the year of this study, no tagged post-smolts from rivers draining into the Irish Sea were detected entering the areas of sea between the Hebrides and mainland Scotland, which is associated with a high density of finfish aquaculture. An important outcome of this study is that a high proportion of post-smolts crossed through multiple legislative jurisdictions and boundaries during their migration. This study provides the basis for spatially explicit assessment of the impact risk of coastal pressures on salmon during their first migration to sea