Developing, choosing and using landscape evolution models to inform field-based landscape reconstruction studies:Developing, choosing and using landscape evolution models

Landscape evolution models (LEMs) are an increasingly popular resource for geomorphologists as they can operate as virtual laboratories where the implications of hypotheses about processes over human to geological timescales can be visualized at spatial scales from catchments to mountain ranges. Hypothetical studies for idealized landscapes have dominated, although model testing in real landscapes has also been undertaken. So far however, numerical landscape evolution models have rarely been used to aid field-based reconstructions of the geomorphic evolution of actual landscapes. To help make this use more common, we review numerical landscape evolution models from the point of view of model use in field reconstruction studies. We first give a broad overview of the main assumptions and choices made in many LEMs to help prospective users select models appropriate to their field situation. We then summarize for various timescales which data are typically available and which models are appropriate. Finally, we provide guidance on how to set up a model study as a function of available data and the type of research question.</p

Subspace-based Identification of a Parallel Kinematic Manipulator Dynamics

This thesis deals with the identification of the dynamics of a Parallel Kinematic Manipulator, namely the Gantry-Tau patented by ABB located in the Robotics lav at LTH, Lund. The approach considered for modelling is subspace-based identification of linear models, where measurements from the robot motion are used to estimate the unknown parameters in the models. Rigid body dynamics and flexible body dynamics are taken into account and a description of the system in terms of a network with spring-damper pairs at the edges, representing the clusters, and masses at the nodes representing the end-effector and the carts, is proposed

Behavioural responses of wild anadromous Arctic char experimentally infested in situ with salmon lice

Salmon lice can impact the marine behaviour, growth, and survival of salmonids, but little is known about their effects on Arctic char. We present behavioural responses from the first dose-response experiment with wild anadromous Arctic char (n = 50) infested in situ with salmon lice (0.0–1.2 lice g−1 fish) in an area with low natural infestations. Infested fish spent less time at sea (mean ± SD = 22 ± 6 d) than non-infested fish (mean ± SD = 33 ± 5 d), and a significant dose response was evident, with even very low louse burdens (−1 fish) reducing the marine feeding time. Furthermore, a negative correlation was present between time spent close to their native watercourse and parasite burden, suggesting that salmon lice influence the marine habitat use of Arctic char. No impact of salmon lice was evident on the return probability, i.e. marine survival. However, the presence of louse-induced mortality cannot be excluded as the modest sample size was only sufficient to detect extreme effects. Reduced marine feeding time and altered marine habitat use will likely have substantial negative effects on growth and fitness, suggesting that impacts of salmon lice must be considered in the conservation of anadromous Arctic char

Behavioural responses of wild anadromous Arctic char experimentally infested in situ with salmon lice

Salmon lice can impact the marine behaviour, growth, and survival of salmonids, but little is known about their effects on Arctic char. We present behavioural responses from the first dose-response experiment with wild anadromous Arctic char (n = 50) infested in situ with salmon lice (0.0–1.2 lice g−1 fish) in an area with low natural infestations. Infested fish spent less time at sea (mean ± SD = 22 ± 6 d) than non-infested fish (mean ±SD = 33 ± 5 d), and a significant dose response was evident, with even very low louse burdens (<0.05 lice g−1 fish) reducing the marine feeding time. Furthermore, a negative correlation was present between time spent close to their native watercourse and parasite burden, suggesting that salmon lice influence the marine habitat use of Arctic char. No impact of salmon lice was evident on the return probability, i.e. marine survival. However, the presence of louse-induced mortality cannot be excluded as the modest sample size was only sufficient to detect extreme effects. Reduced marine feeding time and altered marine habitat use will likely have substantial negative effects on growth and fitness, suggesting that impacts of salmon lice must be considered in the conservation of anadromous Arctic char.publishedVersio

Uncertainty and sensitivity in optode-based shelf-sea net community production estimates

Coastal seas represent one of the most valuable and vulnerable habitats on Earth. Understanding biological productivity in these dynamic regions is vital to understanding how they may influence and be affected by climate change. A key metric to this end is net community production (NCP), the net effect of autotrophy and heterotrophy; however accurate estimation of NCP has proved to be a difficult task. Presented here is a thorough exploration and sensitivity analysis of an oxygen mass-balance-based NCP estimation technique applied to the Warp Anchorage monitoring station, which is a permanently well-mixed shallow area within the River Thames plume. We have developed an open-source software package for calculating NCP estimates and air–sea gas flux. Our study site is identified as a region of net heterotrophy with strong seasonal variability. The annual cumulative net community oxygen production is calculated as (−5 ± 2.5) mol m−2 a−1. Short-term daily variability in oxygen is demonstrated to make accurate individual daily estimates challenging. The effects of bubble-induced supersaturation is shown to have a large influence on cumulative annual estimates and is the source of much uncertainty

Innovation Modeling Grid

This technical document presents the committee driven innovation modeling methodology "Innovation Modeling Grid" in detail. This document is the successor of three publications on IMoG and focuses on presenting all details of the methodologyComment: ~170p, many figures, technical documen

Nucleation and coagulation of particulate matter inside a turbulent exhaust plume of a diesel vehicle

The objective of this study is to develop a physical model to accurately predict the nucleation, coagulation, and dynamics of particulate matter emission from diesel-fueled engines. The uniqueness of this research is that measured particulate matter (PM) size distribution data is not required a priori to solve the nucleation/coagulation equations; instead the PM concentration is predicted based on the fuel sulfur content, fuel to air ratio, exhaust flow rate, and the ambient conditions. This study presents the CFD modeling of an exhaust plume dispersed from a stack pipe of a tractor truck powered by a 330 HP diesel engine. This effort uses the k-epsilon eddy dissipation model to predict the CO2 variation concentration coming out of the stack pipe into the ambient. The effect of the recirculation region near the truck walls on dispersion of CO2 is presented. The predicted results showed an excellent agreement with the experimentally measured values of CO2 concentration, dilution ratio, and the temperature in the wind tunnel. It was predicted that the relative concentration of CO2 from the stack dropped rapidly from 1 to 0.01 within a distance of 2.54 m downstream of the exhaust outlet.;Additionally, the simultaneous effects of nucleation, condensation and coagulation are incorporated in predicting the PM emissions from on-road heavy-duty diesel vehicles. It was predicted that the critical nucleus diameter decreased by approximately 30% and the number concentration increased by a factor of 6 with the increase in relative humidity from 10% to 90% for a fuel with 50 ppm sulfur content. Numerical simulations suggested that the condensation effects are very important near the stack. Ignoring the contribution from condensation term decreased PM count median diameter (CND) from 52 nm to 10 nm. The root mean square error in the numerically predicted particle number concentration was within 14.3% of the experimentally measured values. An increase in CMD from 52 nm to 62 nm was predicted for a distance of 0.51 m from the stack exit to 8.56 m from the stack exit, and the number concentration for the same distance decreased from 8.77 E+6 to 2.1 E+5 No./cm 3