| 1. |
- Aartsen, M. G., et al.
(författare)
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Measurement of the Atmospheric nu(e) Flux in IceCube
- 2013
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 110:15, s. 151105-
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Tidskriftsartikel (refereegranskat)abstract
- We report the first measurement of the atmospheric electron neutrino flux in the energy range between approximately 80 GeV and 6 TeV, using data recorded during the first year of operation of IceCube's DeepCore low-energy extension. Techniques to identify neutrinos interacting within the DeepCore volume and veto muons originating outside the detector are demonstrated. A sample of 1029 events is observed in 281 days of data, of which 496 +/- 66(stat) +/- 88(syst) are estimated to be cascade events, including both electron neutrino and neutral current events. The rest of the sample includes residual backgrounds due to atmospheric muons and charged current interactions of atmospheric muon neutrinos. The flux of the atmospheric electron neutrinos is consistent with models of atmospheric neutrinos in this energy range. This constitutes the first observation of electron neutrinos and neutral current interactions in a very large volume neutrino telescope optimized for the TeV energy range.
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| 2. |
- Bray, Robert John, et al.
(författare)
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A comparison of carbon monoxide yields and particle formation at various global equivalence ratios in vitiated and under-ventilated conditions
- 2023
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Ingår i: Fire Safety Journal. - 0379-7112. ; 141
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Tidskriftsartikel (refereegranskat)abstract
- There have been previous studies comparing experimental methods for the purpose of capturing gaseous yields at a range of global equivalence ratios. However, no work has investigated the capability of the open controlled atmosphere cone calorimeter for collecting such data where its two modes of operation are directly compared. The aim of this study is to compare carbon monoxide yields collected using vitiated and under-ventilated modes of atmospheric control in order to identify the preferable method of replicating carbon monoxide yields reported from larger scale enclosure fire experiments. Cone irradiances of 30, 50 and 65 kW/m2 were applied to PMMA and plywood samples. Vitiated tests were conducted using a mixed air/diluent gas, with an inflow rate of either 100, 150 or 180 L/min, resulting in a reduced oxygen concentration of 17.5 vol. %. Under-ventilated tests were conducted using flow rates of 5, 10 and 20 L/min in an air atmosphere. Particle formations and emissions were also measured using a particle analyser and have been reported herein. Results indicate that the under-ventilated mode of equivalence ratio control offers a more promising method of capturing species yields with favourable comparisons to other bench scale methods.
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| 3. |
- Bray, Robert John, et al.
(författare)
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Burning material behaviour in hypoxic environments : An experimental study examining a representative storage arrangement of acrylonitrile butadiene styrene, polyethylene bubble wrap, and cardboard layers as a composite system
- 2022
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Ingår i: Fire and Materials. - : Wiley. - 0308-0501 .- 1099-1018. ; 46:1, s. 313-328
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Tidskriftsartikel (refereegranskat)abstract
- Cone calorimeter and controlled atmosphere cone calorimeter experiments were conducted on various samples. The intent of the tests was to examine the behavior of uniform and composite samples in a range of thicknesses, irradiances, and oxygen concentrations. Single, uniform layers of acrylonitrile butadiene styrene (ABS) were compared to a composite mix, comprising of ABS with a surface layer of cardboard and a secondary layer of polyethylene bubble wrap (intended to represent a potential storage arrangement). The horizontal samples have been tested at irradiances of 25 and 50 kW/m2 and oxygen concentrations of 20.95%, 17%, and 15% to examine a range of significant variables. Results for the uniform arrangement indicated various correlations, previously observed in the works of others, such as the relationships typically described between applied heat flux, ignitability, heat release rate and the effect of the introduction of hypoxic conditions. However, results were shown to change significantly when samples were arranged to feature composite layers. A hypothesized cause of the behavioral change, namely the soot and char residual introduced from the incomplete combustion of the cardboard layer, highlights further important variables that require consideration in material testing under hypoxic conditions. Such variables, namely specific material behaviors and sample orientation, must be sufficiently captured in the design methodologies of systems reliant upon the introduction of hypoxic conditions. It is concluded that sufficiently capturing a wider range of variables in burning materials under hypoxic conditions will introduce further design resilience and help optimize fire protection/prevention methods.
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| 4. |
- Gehandler, Jonatan, et al.
(författare)
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Tactical depressurization of hydrogen containers with civilian rifle and ammunition
- 2022
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- There can be situations, for example if gas containers have been damaged in a vehicle crash, when the fire and rescue service would like to depressurize the gas containers through shooting with a civilian rifle. Modern high-pressure hydrogen containers are designed for a working pressure of 700 bars. This means that they have a very thick and strong shell made of composite material. At the same time the fire and rescue service only have access to civilian rifles and ammunition that can be bought for hunting purposes. Thus, tactical and safe depressurization of hydrogen containers is a big challenge. RISE have, together with the Södra Älvsborgs Fire and Rescue Services (SÄRF), Swedish Civil Contingency Agency, and Lund University conducted shooting tests of gas tanks mounted on a hydrogen gas vehicle and three stand-alone hydrogen gas tanks. The shooting tests were conducted at Remmene shooting field in Sweden. Thirteen shooting tests with hydrogen tanks placed in favouarable positions were performed. Out of these, only four tests were succesful in puncturing the individual gas tank in a single shot. Furthermore, two unwanted events occurred; one rupture (after 7 shots) and two powerful jets (after 20 and one shot respectively). This shows that further development and research is required in order to develop a method to safely depressurize high pressure hydrogen tanks.
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| 5. |
- Ibrahim, Muhammad Asim, 1980-, et al.
(författare)
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Early detection of deep-seated smouldering fires in wood waste storage using ERT
- 2024
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Ingår i: Waste Management. - : Elsevier. - 0956-053X .- 1879-2456. ; 182, s. 215-224
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Tidskriftsartikel (refereegranskat)abstract
- Incidents of waste and biofuel fires are common at all stages of the waste recycling chain and have grave implications for business, employees, firefighters, society, and environment. An early detection of waste and biofuel fires in the smouldering stage could save precious lives, resources, and our environment. Existing fire detection methodologies e.g. handheld temperature sensors, IR cameras, gas sensors, and video and satellite-based monitoring techniques have inherent limitations to efficiently detect smouldering fires. An attempt was made to explore the potential of electrical resistivity tomography (ERT) as an alternate tool to address the problem. In the experiments an externally powered resistive wire was employed to initiate the smouldering fire inside the test material (wood pellets, wood shavings, wood fines). Time series of ERT that followed the initiation and development of smouldering were recorded using an automated monitoring instrument setup. The actual geometry of the experimental sample container and electrode setup was integrated in the 3D finite element method (FEM) model grid to perform inverse numerical modelling (inversion) and to develop resistivity tomographic images. The study shows a sharp increase in ratio of resistivity (?/?? ≥ 50 %) in the test material in the region of smouldering hotspot and demonstrates the potential use of ERT technique for the detection of smouldering hotspots in silos and pile storage of organic material such as wood-based fuels, wood waste, coal, municipal solid waste (MSW), recyclables etc. More research is however required for enabling the use of this technique at the practical scale for different storage conditions.
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| 6. |
- Leibovitzh, Haim, et al.
(författare)
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Immune response and barrier dysfunction-related proteomic signatures in preclinical phase of Crohn's disease highlight earliest events of pathogenesis
- 2023
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Ingår i: Gut. - : BMJ Publishing Group Ltd. - 0017-5749 .- 1468-3288. ; 72:8, s. 1462-1471
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: The measure of serum proteome in the preclinical state of Crohn's disease (CD) may provide insight into biological pathways involved in CD pathogenesis. We aimed to assess associations of serum proteins with future CD onset and with other biomarkers predicting CD risk in a healthy at-risk cohort.DESIGN: In a nested case-control study within the Crohn's and Colitis Canada Genetics Environment Microbial Project (CCC-GEM) cohort, which prospectively follows healthy first-degree relatives (FDRs), subjects who developed CD (n=71) were matched with four FDRs remaining healthy (n=284). Using samples at recruitment, serum protein profiles using the Olink Proximity Extension Assay platform was assessed for association with future development of CD and with other baseline biomarkers as follows: serum antimicrobial antibodies (AS: positive antibody sum) (Prometheus); faecal calprotectin (FCP); gut barrier function using the fractional excretion of lactulose-to-mannitol ratio (LMR) assay.RESULTS: We identified 25 of 446 serum proteins significantly associated with future development of CD. C-X-C motif chemokine 9 (CXCL9) had the highest OR with future risk of CD (OR=2.07 per SD, 95% CI 1.58 to 2.73, q=7.9e-5), whereas matrix extracellular phosphoglycoprotein had the lowest OR (OR 0.44, 95% CI 0.29 to 0.66, q=0.02). Notably, CXCL9 was the only analyte significantly associated with all other CD-risk biomarkers with consistent direction of effect (FCP: OR=2.21; LMR: OR=1.67; AS: OR=1.59) (q<0.05 for all).CONCLUSION: We identified serum proteomic signatures associated with future CD development, reflecting potential early biological processes of immune and barrier dysfunction.
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| 7. |
- Lindgren, Johan, et al.
(författare)
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Fossil insect eyes shed light on trilobite optics and the arthropod pigment screen
- 2019
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Ingår i: Nature. - : Nature Publishing Group. - 0028-0836 .- 1476-4687. ; 573:7772, s. 122-125
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Tidskriftsartikel (refereegranskat)abstract
- Fossilized eyes permit inferences of the visual capacity of extinct arthropods1–3. However, structural and/or chemical modifications as a result of taphonomic and diagenetic processes can alter the original features, thereby necessitating comparisons with modern species. Here we report the detailed molecular composition and microanatomy of the eyes of 54-million-year-old crane-flies, which together provide a proxy for the interpretation of optical systems in some other ancient arthropods. These well-preserved visual organs comprise calcified corneal lenses that are separated by intervening spaces containing eumelanin pigment. We also show that eumelanin is present in the facet walls of living crane-flies, in which it forms the outermost ommatidial pigment shield in compound eyes incorporating a chitinous cornea. To our knowledge, this is the first record of melanic screening pigments in arthropods, and reveals a fossilization mode in insect eyes that involves a decay-resistant biochrome coupled with early diagenetic mineralization of the ommatidial lenses. The demonstrable secondary calcification of lens cuticle that was initially chitinous has implications for the proposed calcitic corneas of trilobites, which we posit are artefacts of preservation rather than a product of in vivo biomineralization4–7. Although trilobite eyes might have been partly mineralized for mechanical strength, a (more likely) organic composition would have enhanced function via gradient-index optics and increased control of lens shape.
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| 8. |
- Madsen, Dan, et al.
(författare)
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Fire-Induced Radiological Integrated Assessment : Fire properties of selected materials and products
- 2019
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Characterization of emissions from fires in a laboratory-controlled environment are presented in this report. The project is initiated by the CERN HSE Unit and is called FIRIA, Fire-Induced Radiological Integrated Assessment. The objective of FIRIA is to enhance the knowledge of aerosols emitted from fires in order to develop dispersion models of radiologically-activated material in case of fire. In this report, several normally occurring combustible products and materials are tested in a standardized setup for fire tests, the cone calorimeter. In the cone calorimeter, standardized fire tests according to ISO 5660-1:2015 have been performed as well as fire tests at reduced oxygen concentrations in a vitiated air chamber. As an additional setup, aerosol measurement equipment was coupled to the cone calorimeter ventilation duct to characterize the emitted aerosols as in the particle size distribution, mass yield and elemental analysis.The results show peak heat release rates for oil at 1100 kW/m2 at an incident heat flux of 50 kW/m2. Similar results for the plastic materials were 800 kW/m2. For cables and insulating plastic materials peak heat release rates at an incident heat flux of 50 kW/m2 were around 350 kW/m2. Significant for most of the cables was a heat release rate curve with two distinct peaks. This is proposed to be due to the outer combustible sheath burning first followed by the interior plastic insulating material of the cables burning. There could also be heat transfer effects and cracking of the material surface contributing to the two peaks. Nevertheless, for some cables a low incident heat flux led to only one peak indicating that only the sheath ignited. Time to ignition varied between the materials but was increased as the incident heat flux decreased. Reduced oxygen concentration in the vitiated air chamber also prolonged the ignition time as well as the heat release rates. The critical heat flux to ignite the cables was calculated to be just below 10 kW/m2. The oil and two cable types were tested in the vitiated air chamber to perform tests at reduced oxygen concentrations. These tests were performed to retrieve specific fire properties as well as specific emissions from such conditions. The tests were performed with a progressively lower oxygen concentrations until no ignition of the sample occurred. Results showed an ignition limit around 11-13 % oxygen at incident heat fluxes of 20-30 kW/m2. The tests in the vitiated air chamber is described in subreport FIRIA- Fire properties of selected materials and products in reduced oxygen conditions.
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| 9. |
- Madsen, Dan, et al.
(författare)
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Fire-Induced Radiological Integrated Assessment : Fire properties of selected materials and products in reduce oxygen conditions
- 2019
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Characterization of emissions from fires in a laboratory-controlled environment are presented in this report. The project is initiated by the CERN HSE Unit and is called FIRIA, Fire-Induced Radiological Integrated Assessment. The objective of FIRIA is to enhance the knowledge of aerosols emitted from fires in order to develop dispersion models of radiologically-activated material in case of fire. Standard cone calorimeter test were done on a variety of combustible products and materials and the results are presented in the report FD03 Fire-Induced Radiological Integrated Assessment - Fire properties of selected materials and products.In this report, a vitiated air chamber was used to test an oil and two cables at reduced oxygen concentrations that were also tested in the FD03 report. The vitiated air chamber was attached to the standard cone calorimeter and a reduction in oxygen concentration was achieved by mixing nitrogen with compressed air. This general setup has been referred to as the open controlled atmosphere cone calorimeter (CACC).This report contains fire properties of the oil and cables at different irradiances and oxygen concentrations. The properties included are the ignition time, mass loss rate, heat release rate per unit area (HRRPUA), carbon dioxide yield, carbon monoxide yield, heat of combustion, and extinction coefficient.The results from the reduced oxygen concentration tests were compared with the results from the FD03 report. Some observations from the comparison are: An increase in the ignition time when compared to tests done in the standard cone calorimeter occurred for the oil and both cables at the lowest oxygen concentration tested for each irradiance level. The average carbon monoxide yields remained relatively constant or increased with decreases in the oxygen concentration. A reduction in the oxygen concentration generally resulted in a decrease in the mass loss rate and heat release rate per unit area (HRRPUA). However, one of the cables, referred to as cable 4 (C04), did not have a reduction in the mass loss rate and HRRPUA when exposed to an irradiance of 50 kW/m2. Cable 8 (C08) also had a higher peak mass loss rate and peak HRRPUA when tested at an oxygen concentration of 17% though the mass loss rate and HRRPUA was lower than the standard cone calorimeter result for most of the test.The limiting oxygen concentration using nitrogen to dilute air was also estimated at an irradiance of 20 kW/m2 for the oil and 30 kW/m2 for the cables. The estimated limiting oxygen concentrations were: Oil: between 11% (no ignition) and 13% (ignition) at an irradiance of 20 kW/m2 Cable 4: between 12% (no ignition) and 14% (ignition) at an irradiance of 30 kW/m2 Cable 8: between 13% (no ignition) and 15% (ignition) at an irradiance of 30 kW/m2
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| 10. |
- Madsen, Dan, et al.
(författare)
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Fire properties of borated polyethylene
- 2015
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Ingår i: Fire and Materials 2015 - 14th International Conference and Exhibition, Proceedings. ; , s. 429-441
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Konferensbidrag (refereegranskat)abstract
- This work has been made as a thesis for a BSc degree in Fire Protection Engineering at Lund University. The work has been supported and funded by ESS AB, European Spallation Source, in Lund. ESS AB is a publicly held company, owned by Sweden and Denmark as host countries. These host countries, together with at least 17 other European countries, will build and establish a multidisciplinary research center just outside of Lund. The research will be based on the world's most powerful neutron source and be 30 times brighter than the leading active facilities today. The scope and objective of this work was to evaluate and determine fire properties for a material that will be used for radiation shielding at the Research center. Traditionally two materials, borated paraffin and borated polyethylene, are used for radiation shielding at neutron-based research laboratories. Since base paraffin and base polyethylene are known as combustible materials with a high-energy content, it is of great interest to determine the actual fire properties of the borated versions. As the application of the borated paraffin will be in encapsulated blockhouse wax walls of steel, the prioritized objective in this paper was to evaluate the borated polyethylene that was initially considered to be used as unprotected sheets for radiation shielding. The borated polyethylene was bought at a global supplier of plastic products. Some current building regulations together with valuable information concerning the material were also discussed. The results of the work are based on literature research, interviews, discussions and test methods (cone calorimeter tests, parallel panel tests and combustion under an exhaust hood). Limitations of the work are that it does not consider toxicity, smoke production or a measured heat release rate in the full scale tests. The Euroclass classification according to European fire classification of materials, construction products and building elements was only in the application as a construction product or surface lining and not as flooring. The evaluation of borated polyethylene shows that the fire properties vary depending on the orientation of the material. When burning in a horizontal orientation the Boron oxide establish a suffocating residue layer that dampens the release of pyrolysis gases but in vertical orientation the Boron oxide runs off with the melted material and does not form a suffocating residue layer. When burning in vertical orientation the borated polyethylene also has burning droplets. Values obtained in cone calorimeter tests were used in a screening method, Conetools, to determine the borated polyethylene as D-classified material according the Euroclasses by the European fire classification of materials, construction products and building elements. The actual classification and the burning droplets demands fire protection measures in most building classes according a simplified design by the Building Regulations of the Swedish Board of Housing, Building and Planning, BBR. Future work to ensure a safe use of combustible materials for radiation shielding should be to verify the actual applications of fire protections measures. This verification is strengthened in the guideline BFS 2013:11 chapter 3.4 Skyddad brandenergi (Swedish). Further on in the future it would be interesting to develop a new material for radiation shielding that can be used as self-supporting building elements with fire properties that does not demand fire protection measures or extended fire protection systems.
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