| 1. |
- Carbone, Lisa, et al.
(author)
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Generators and relations for (generalised) Cartan type superalgebras
- 2019
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In: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 1194:1
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Conference paper (peer-reviewed)abstract
- In Kac's classification of finite-dimensional Lie superalgebras, the contragredient ones can be constructed from Dynkin diagrams similar to those of the simple finite-dimensional Lie algebras, but with additional types of nodes. For example, A(n-1,0) = s (1|n) can be constructed by adding a "gray" node to the Dynkin diagram of An-1 = s (n), corresponding to an odd null root. The Cartan superalgebras constitute a difierent class, where the simplest example is Wpnq, the derivation algebra of the Grassmann algebra on n generators. Here we present a novel construction of Wpnq, from the same Dynkin diagram as A(n-1,0), but with additional generators and relations.
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| 2. |
- Goienetxea Uriarte, Ainhoa, 1983-, et al.
(author)
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System design and improvement of an emergency department using Simulation-Based Multi-Objective Optimization
- 2015
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In: Journal of Physics, Conference Series. - : Institute of Physics Publishing (IOPP). - 1742-6588 .- 1742-6596. ; 616:1
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Journal article (peer-reviewed)abstract
- Discrete Event Simulation (DES) is nowadays widely used to support decision makers in system analysis and improvement. However, the use of simulation for improving stochastic logistic processes is not common among healthcare providers. The process of improving healthcare systems involves the necessity to deal with trade-off optimal solutions that take into consideration a multiple number of variables and objectives. Complementing DES with Multi-Objective Optimization (SMO) creates a superior base for finding these solutions and in consequence, facilitates the decision-making process. This paper presents how SMO has been applied for system improvement analysis in a Swedish Emergency Department (ED). A significant number of input variables, constraints and objectives were considered when defining the optimization problem. As a result of the project, the decision makers were provided with a range of optimal solutions which reduces considerably the length of stay and waiting times for the ED patients. SMO has proved to be an appropriate technique to support healthcare system design and improvement processes. A key factor for the success of this project has been the involvement and engagement of the stakeholders during the whole process.
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| 3. |
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| 4. |
- Espinoza-Andaluz, Mayken, et al.
(author)
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Applicability of the lattice Boltzmann method to determine the ohmic resistance in equivalent resistor connections
- 2017
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In: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 936:1
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Journal article (peer-reviewed)abstract
- Knowing the ohmic resistance in the materials allow to know in advance its electrical behavior when a potential difference is applied, and therefore the prediction of the electrical performance can be achieved in a most certain manner. Although the Lattice Boltzmann method (LBM) has been applied to solve several physical phenomena in complex geometries, it has only been used to describe the fluid phase, but applicability studies of LBM on the solid-electric-conducting material have not been carried out yet. The purpose of this paper is to demonstrate the accuracy of calculating the equivalent resistor connections using LBM. Several series and parallel resistor connections are effected. All the computations are carried out with 3D models, and the domain materials are designed by the authors.
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| 5. |
- Folsom, B., et al.
(author)
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Approximating nonlinear forces with phase-space decoupling
- 2017
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In: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 874:1
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Journal article (peer-reviewed)abstract
- Beam tracking software for accelerators typically falls into two categories: fast envelope simulations limited to linear beam optics, and slower multiparticle simulations that can model nonlinear effects. To find a middle ground between these approaches, we introduce virtual coordinates in position and momentum which have a cross-dependency (i.e. p∗ = f (x 0) where x 0 is an initial position and p∗ is a virtual projection of momentum onto the position axis). This technique approximates multiparticle simulations with a significant reduction in calculation cost.
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| 6. |
- Joshi, N., et al.
(author)
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MEMS Based Micro Aerial Vehicles
- 2016
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In: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 757:1
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Conference paper (peer-reviewed)abstract
- Designing a flapping wing insect robot requires understanding of insect flight mechanisms, wing kinematics and aerodynamic forces. These subsystems are interconnected and their dependence on one another affects the overall performance. Additionally it requires an artificial muscle like actuator and transmission to power the wings. Several kinds of actuators and mechanisms are candidates for this application with their own strengths and weaknesses. This article provides an overview of the insect scaled flight mechanism along with discussion of various methods to achieve the Micro Aerial Vehicle (MAV) flight. Ongoing projects in Chalmers is aimed at developing a low cost and low manufacturing time MAV. The MAV design considerations and design specifications are mentioned. The wings are manufactured using 3D printed carbon fiber and are under experimental study. © Published under licence by IOP Publishing Ltd.
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| 7. |
- Maercker, Matthias, 1979
(author)
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ALMA observations of the not-so detached shell around the carbon AGB star R Sculptoris
- 2016
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In: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 728:2, s. Aricle no. 022006-
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Conference paper (peer-reviewed)abstract
- I present our ALMA observations of the CO emission around the carbon AGB star R Sculptoris. The data reveal the known detached shell and a previously unknown, binary induced, spiral shape. The observations confirm a formation of the shell during a thermal pulse about 2300 years ago. The full analysis of the ALMA data shows that the shell around R Scl in fact is entirely filled with molecular gas, and hence not as detached as previously thought. This has implications for the mass-loss rate evolution immediately after the pulse, indicating a much higher mass-loss rate than previously assumed. Comparing the ALMA images to our optical observations of polarised, dust scattered light, we further show that the distributions of the dust and gas coincide almost perfectly, implying a common evolution of the dust and gas, and constraining the wind-driving mechanism. The mass-loss process and amount of mass lost during the thermal pulse cycle affect the chemical evolution of the star, its lifetime on the AGB, and the return of heavy elements to the ISM. New high-resolution ALMA observations constrain the parameters of the binary system and the inner spiral, and will allow for a detailed hydrodynamical modelling of the gas and dust during and after the last thermal pulse. Our results present the only direct measurements of the thermal pulse evolution currently available. They greatly increase our understanding of this fundamental period of stellar evolution, and the implications it has for the chemical evolution of evolved stars, the ISM, and galaxie.
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| 8. |
- Mantulnikovs, K., et al.
(author)
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Neutron guide shielding for the BIFROST spectrometer at ESS
- 2016
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In: VI European Conference On Neutron Scattering (ECNS2015). - : IOP Publishing. ; 746:1
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Conference paper (peer-reviewed)abstract
- We report on the study of fast-neutron background for the BIFROST spectrometer at ESS. We investigate the effect of background radiation induced by the interaction of fast neutrons from the source with the material of the neutron guide and devise a reasonable fast, thermal/cold neutron shielding solution for the current guide geometry using McStas and MCNPX. We investigate the effectiveness of the steel shielding around the guide by running simulations with three different steel thicknesses. The same approach is used to study the efficiencies of the steel wall a flat cylinder pierced by the guide in the middle and the polyethylene layer. The final model presented here has a 3 cm thick steel shielding around the guide, 30 cm of polyethylene around the shielding, two 5 mm thick B4C layers and a steel wall at position Z = 38 m, being 1 m thick and 10 m in radius. The final model finally proves that it is sufficient to bring the background level below the cosmic neutron rate, which defines an order of magnitude of the lowest obtainable background in the instruments.
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| 9. |
- Nystedt, Fredrik
(author)
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On the Use of Risk Concepts in Fire Safety Engineering
- 2018
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In: 3rd European Symposium on Fire Safety Science 12–14 September 2018, Nancy, France. - : IOP Publishing. - 1742-6588. ; 1107
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Conference paper (peer-reviewed)abstract
- Design for fire safety may be carried out by two generic approaches - a set of prescriptive rules or by a performance-based approach where analytical tools are used to verify fire safety towards a set of functional requirements and performance criteria given by the building code. Normally, these two methods are mixed when design fire safety within a building. The option to apply fire safety engineering to the design of buildings has been available during the last 20 to 40 years, depending on which aspect of fire safety being considered. Still, the fire protection of a building too often relies on general recommendations rather than scientifically-based solutions, due to a lack of standardised verification methods, acceptance criteria and procedures to ensure high quality fire safety design. The concept of risk, i.e. the combination of the probability of a fire and a quantified measure of its consequence, has been thoroughly investigated in several fire safety engineering applications over the last decades. Although there are techniques available that allow designers to evaluate fire risks, risk acceptance criteria are missing in general. Structural fire safety design is the exemption having defined target reliabilities. Although these criteria only address the likelihood of collapse of structural element and not explicitly the characteristics of the failure. Structural elements can be provided with fire resistance to control the spread of fire or to prevent structural collapse, or both and it is not uncommon to perform trade-offs between passive and active fire protection systems. But, very little effort has previously been made to understand the fundamental differences between these systems regarding their reliability and failure modes. Performance-based design of structural elements uses a heat exposure model to quantify the thermal load of the fire. The thermal load is characterised by the fire load (duration) and the intensity (air supply). Characteristic values of the fire load are found in various sources and commonly given in the building code, which ought to be used when designing for fire safety. A probabilistic approach was introduced in the 1980s where the probability of fire is expressed as a function of the probability of fire occurrence, the probability of a flashover and the probability of failure given a fully developed fire. Thus, the target probability of failure could be achieved by applying safety measures that alters the probability of any of these events. Currently, fire sprinklers do allow for a reduction in design fire load, but not other active safety system can be considered explicitly. Passive as well as active system for fire safety could both be considered as appropriate provisions to achieve sufficient safety. Even though there are support of trade-offs between passive and active provisions, current regulations, guidance as well as practise do not treat the different aspect of risk related to these systems. By only considering the probability of collapse, the design could deviate from overall societal requirements on avoiding catastrophes or principles of robustness stating that consequences should not be disproportionate to their cause. Traditionally, passive systems are assumed more robust. These findings are probably related to the concepts where target reliabilities are evaluated as the system is designed. Sprinklers are, on the other hand, assigned a probability of successful operation based on decades of statistics. This is an unfair comparison between the systems as a properly design sprinkler system always would prevent a fully developed fire, thus requiring no specific fire resistance on separating and structural elements. Naturally, this is not the path forward as the failure modes of both types of system must be treated and understood. Active systems could be argued to be more forgiven as the they do not care what mistakes are made to cause a fire, neither do they care if occupants act as planed or not. Passive systems are more sensitive to building use when e.g. doors are kept open. Future performance criteria and risk acceptance criteria should not focus solely on probabilities. Emphasis must be put on establish criteria that measure the risk of the unwanted event considering type of initiating event, number of barriers, expected consequence, possibility of damage control, etc. Not until such criteria are available the full potential of performance-based fire safety design cannot be utilised.
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| 10. |
- Rodriguez, D. Martin, et al.
(author)
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How to polarise all neutrons in one beam : a high performance polariser and neutron transport system
- 2016
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In: VI European Conference On Neutron Scattering (ECNS2015). - : IOP Publishing. ; 746:1
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Conference paper (peer-reviewed)abstract
- Polarised neutron beams are used in disciplines as diverse as magnetism, soft matter or biology. However, most of these applications often suffer from low flux also because the existing neutron polarising methods imply the filtering of one of the spin states, with a transmission of 50% at maximum. With the purpose of using all neutrons that are usually discarded, we propose a system that splits them according to their polarisation, flips them to match the spin direction, and then focuses them at the sample. Monte Carlo (MC) simulations show that this is achievable over a wide wavelength range and with an outstanding performance at the price of a more divergent neutron beam at the sample position.
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