141 research outputs found
Cold gas in hot star clusters: the wind from the red supergiant W26 in Westerlund 1
No full textThe massive red supergiant W26 in Westerlund 1 is one of a growing number of red supergiants shown to have winds that are ionized from the outside in. The fate of this dense wind material is important for models of second generation star formation in massive star clusters. Mackey et al
Investigating dusty red supergiant outflows in Westerlund 1 with 3D hydrodynamic simulations
No full textContext. Recent JWST observations towards Westerlund 1 have revealed extensive nebular emission associated with the cluster. Given the age of the region and the proximity of that material to massive stars, it cannot be primordial star-forming gas and the origin is uncertain.
Aims. We aim to determine whether the nebular emission in Westerlund 1 is due to ablation flows from red supergiant (RSG) stars embedded in the cluster wind driven by the Wolf-Rayet stars in the cluster core. We also aim to explore the efficiency of mass loading for the RSG wind in this scenario.
Methods. We used 3D hydrodynamic simulations with the PION code to study the interaction between the cluster and RSG winds. We compared our simulations with the JWST observations by generating synthetic dust-emission maps.
Results. We find that the ablation flow morphology – which shows clumps and instabilities – is consistent with the observations towards Westerlund 1. Synthetic observations at 11 µm predict fluxes in the ablation flow of ~1000–6000 MJy ster−1, which is consistent with the unsaturated components of the JWST F1130W observations in the vicinity of the RSGs in the region. This good agreement is achieved without any consideration of polycyclic aromatic hydrocarbons (PAHs), which have a known 11.3 µm feature that appears in the F1130W band. This suggests that the environment is not conducive to PAH formation and/or the ablation flow is PAH-depleted by wind and radiation action.
Conclusions. Ablation of RSG winds can explain the observed nebulosity in Westerlund 1, at least in the vicinity of the RSGs. Further observations are encouraged to enable detailed studies of these interactions
Nanoparticles from shipping and road traffic
No full textIn the urban environment road traffic is the dominant source of aerosol particles while in
coastal and harbour areas shipping is also a significant source. For shipping there are no direct
regulations regarding particle emissions. For road traffic the emissions of particle mass has
been regulated for over two decades but only during the last few years particle number has
been included in emission regulations. Generally, nanoparticles are better described by their
number rather than mass since they contribute insignificantly to the total particle mass of
urban particles. Furthermore, particle number is believed to be a better metric for describing
health effects than particle mass. Particle number and mass of the nanoparticles is however
more difficult to measure both because of their small size but also because they are part of a
highly dynamic system with constant exchange with the gas phase.
The studies described in this thesis were conducted with the aim of increasing the knowledge
on the emissions of nanoparticles from shipping and city transit buses. The focus has been on
size resolved particle number emissions. The evolution of nanoparticles was studied by
conducting measurements by extractions from the inside of the exhaust system and from the
exhaust plume.
Emissions of nanoparticles depend on combustion conditions, exhaust aftertreatments, the
fuel and ship/vehicle variations. In this study engine load and engine speed was found to be
the most important factors studying individual vehicles or ships. For example, manoeuvring
of a ship in the port areas was found to contribute to up to a factor of 64 times higher particle
number emissions than during stable engine load at open sea. It was found the variation
between vehicles or ships was the most important factor when studying a fleet of vehicles or
ships operating on different fuels and/or exhaust aftertreatments. For example, from a
selection of 35 buses a few diesel fuelled buses were responsible for most of the particle mass
emissions while a few buses fuelled with compressed natural gas were responsible for most of
the particle number emissions. Controlling these extreme emitting individuals or specific
operating conditions could be an effective way of reducing the total emission of
nanoparticles.
Nanoparticles extracted from the exhaust system are different compared to the nanoparticles
found in the exhaust plume. In the ship exhaust system a soot mode was often found together
with a volatile nucleation mode. In the ship exhaust plume the volatile nucleation mode
coagulated quickly leaving soot covered with volatile material. Soot emissions were lower for
the studied buses which supress condensation and the lower total number concentrations in
the bus emissions reduce the rate of coagulation. Nucleation mode particles for the studied
buses were found both in the exhaust system and in the exhaust plume. Nucleation versus
condensation of volatile material has implications for the measured particle number and in
addition, soot covered with volatile material has a denser structure than soot without
condensable material.
Non-volatile particles with a diameter of ~10 nm were found in the ship plume measurements
which were not present in the on-board measurements. A hypothesis of organo-sulphates
being formed in the exhaust plume was presented which could explain the formation of these
particles. This emphasis that processes in the atmosphere can be of importance but they will
not be covered in on-board or laboratory measurements
Model Predictive Control of a Combined EGR/SCR HD Diesel Engine
No full textMaterials Noise, Vibration and Harshness Parts and Components Power and Propulsion Quality, Reliability and Durability Safety Tests and Testing Transportation Systems Vehicles and Performance Other Options Papers by Event SAE Home > Papers> By Event> SAE 2010 World Congress & Exhibition Model Predictive Control of a Combined EGR/SCR HD Diesel Engine Date Published: 2010-04-12Paper Number: 2010-01-1175 DOI: 10.4271/2010-01-1175 Author(s): Claes Westerlund - Scania CV AB Bjorn Westerberg - Scania CV AB Ingemar Odenbrand - Lund Univ. Rolf Egnell - Lund Univ. View All CollapseAbstract Achieving upcoming HD emissions legislation, Euro VI / EPA 10, is a challenge for all engine manufacturers. A likely solution to meet the NO x limit is to use a combination of EGR and SCR. Combining these two technologies poses new challenges and possibilities when it comes to optimization and calibration
Maine Sculptors: A Catalog
No full textThe works of several Maine sculptors are featured. Included are Celeste Roberge, John Bisbee, Lauren Fensterstock, William Zorach, Jonathan Borofsky, Jesse Salisbury, Andreas Von Huene, John Bonsignore, Daphne Pulsifer, Andy Rosen, Lin Lisberger, Stephan Porter, Cabot Lyford, Robert Laurent, Bernard Langlais, Mark Herrington, Charlie Hewitt, Carole Whelan, Melina Westerlund, Asherah Cinnamon, Robert Indiana, Jean Noon, Louise Nevelson, and Judd Hartman. [images
Model Predictive Control of a Combined EGR/SCR HD Diesel Engine
No full textMaterials Noise, Vibration and Harshness Parts and Components Power and Propulsion Quality, Reliability and Durability Safety Tests and Testing Transportation Systems Vehicles and Performance Other Options Papers by Event SAE Home > Papers> By Event> SAE 2010 World Congress & Exhibition Model Predictive Control of a Combined EGR/SCR HD Diesel Engine Date Published: 2010-04-12Paper Number: 2010-01-1175 DOI: 10.4271/2010-01-1175 Author(s): Claes Westerlund - Scania CV AB Bjorn Westerberg - Scania CV AB Ingemar Odenbrand - Lund Univ. Rolf Egnell - Lund Univ. View All CollapseAbstract Achieving upcoming HD emissions legislation, Euro VI / EPA 10, is a challenge for all engine manufacturers. A likely solution to meet the NO x limit is to use a combination of EGR and SCR. Combining these two technologies poses new challenges and possibilities when it comes to optimization and calibration
Följa upp och synliggöra barns lärprocesser : En kvalitativ studie om hur pedagoger arbetar och resonerar kring hur barns lärprocesser följs upp och synliggörs
No full textTitle: Making learning visible in a preschool setting- A qualitative study of how teachers work and evaluate how children’s learning can be visualized Term: Autumn 2015 Author: Emelie Persson and Annelie Westerlund Mentor: Maria Rosén The objective of this study is to examine how two departments at a preschool work specifically to visualize children’s learning processes, both from a Child Perspective and from the Children's Perspective. The purpose is to investigate questions concerning how teachers follow up and visualize the children’s learning process and how preschool teachers evaluate to what extent children's learning processes should be made visible. The study is qualitative and ethnographically inspired. We have conducted participating observations in order to examine how teachers follow up and visualize children’s learning processes. In addition to this we have made unstructured interviews to examine how preschool teachers evaluate how children's learning processes are visualized. The theoretical starting point we used is Dewey’s Pragmatism which is based on the assumption that children's learning emerge out of their own experiences and interests. The result shows that the pre-school teachers follow up and visualize the children's learning processes in different ways. They incorporate different steps of the process and they structure the environment by having materials easily accessible to the children in order to make learning processes based on children’s interests possible. The teachers act as role models when it comes to vocal expression and through active dialogues they create opportunities for the children to reflect on what they’ve learnt. The teachers also actively work to allow the children to express their thoughts and opinions, and to integrate these into the learning process. The most prominent result of the study showed that the teachers’ interaction with the children were shown by their attendance, responsiveness, commitment, as well as to their showing an interest in the children’s many different worlds of experiences. Keywords: Pre-school, learning processes, children's learning Nyckelord: Förskola, lärprocesser, barns lärand
Följa upp och synliggöra barns lärprocesser : En kvalitativ studie om hur pedagoger arbetar och resonerar kring hur barns lärprocesser följs upp och synliggörs
No full textTitle: Making learning visible in a preschool setting- A qualitative study of how teachers work and evaluate how children’s learning can be visualized Term: Autumn 2015 Author: Emelie Persson and Annelie Westerlund Mentor: Maria Rosén The objective of this study is to examine how two departments at a preschool work specifically to visualize children’s learning processes, both from a Child Perspective and from the Children's Perspective. The purpose is to investigate questions concerning how teachers follow up and visualize the children’s learning process and how preschool teachers evaluate to what extent children's learning processes should be made visible. The study is qualitative and ethnographically inspired. We have conducted participating observations in order to examine how teachers follow up and visualize children’s learning processes. In addition to this we have made unstructured interviews to examine how preschool teachers evaluate how children's learning processes are visualized. The theoretical starting point we used is Dewey’s Pragmatism which is based on the assumption that children's learning emerge out of their own experiences and interests. The result shows that the pre-school teachers follow up and visualize the children's learning processes in different ways. They incorporate different steps of the process and they structure the environment by having materials easily accessible to the children in order to make learning processes based on children’s interests possible. The teachers act as role models when it comes to vocal expression and through active dialogues they create opportunities for the children to reflect on what they’ve learnt. The teachers also actively work to allow the children to express their thoughts and opinions, and to integrate these into the learning process. The most prominent result of the study showed that the teachers’ interaction with the children were shown by their attendance, responsiveness, commitment, as well as to their showing an interest in the children’s many different worlds of experiences. Keywords: Pre-school, learning processes, children's learning Nyckelord: Förskola, lärprocesser, barns lärand
The young massive stellar cluster Westerlund 1 in gamma rays as seen with H.E.S.S.
No full textMassive stellar clusters have recently been hypothesised as candidates for the acceleration of hadronic cosmic rays up to PeV energies. Previously, the H.E.S.S. Collaboration has reported about very extended -ray emission around Westerlund 1, a massive young stellar cluster in the Milky Way. In this contribution we present an updated analysis that employs a new analysis technique and is based on a much larger data set, allowing us to constrain better the morphology and the energy spectrum of the emission. The analysis technique used is a three-dimensional likelihood analysis, which is especially well suited for largely extended sources. The origin of the -ray emission will be discussed in light of multi-wavelength observations
Tillämpningen av flerstegstvistlösningsklausuler : En komparativ analys av utvalda jurisdiktioner
No full textMulti-tier dispute resolution (“MDR”) clauses are tailored clauses that prescribe a layered process of dispute resolution, wherein parties in dispute must first undertake one or more alternative dispute resolution processes before they can refer the dispute to adjudication before an arbitral tribunal or a court. The use of MDR-clauses has become increasingly commonplace in Nordic commercial contracts, but the extent to which a Nordic arbitral tribunal or court would be willing to enforce this order of dispute resolution, and what remedies or sanctions such enforcement would result in, are questions that neither legislators nor legal scholars have provided a comprehensive and satisfying answer to. This scholarly and legislative gap in turn calls into question the usefulness and efficiency of this increasingly common contractual clause.
This thesis aims to answer the question of what the Nordic (with a primary focus on the Finnish) legal systems can learn from the way legal scholars, legislators and judges in the Continental European and Anglo-American legal systems have approached the enforcement of MDR-clauses, and how such lessons could aid in creating a working legislative framework for their enforcement in the Nordics.
As a result of a general lack of discussion on the subject by Nordic lawyers, this thesis primarily employs a comparative method. Specifically, the comparative research focuses on jurisdictions within the Anglo-American legal system and their Continental European counterparts, where relatively definitive and mostly consistent case law and scholarly debate regarding the enforcement of MDR-clauses has emerged over time.
While the analysis concludes that enforceability of MDR-clauses in the Nordics is uncertain at best, it also identified several key concepts necessary for a functional legislative scheme allowing for such enforcement. Given the general disinterest in the subject matter shown by Nordic lawyers, this thesis concludes that legislative change is unlikely to develop on a national level, but rather that international harmonization, preferably from the EU, is required to effect change in the enforceability of MDR-clauses
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