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Kassman H.,Vattenfall | Kassman H.,Chalmers University of Technology | Bafver L.,Technical Research Institute of Sweden | Amand L.-E.,Chalmers University of Technology
Combustion and Flame | Year: 2010

This paper is based on results obtained during co-combustion of wood pellets and straw in a 12MW circulating fluidised bed (CFB) boiler. Elemental sulphur (S) and ammonium sulphate ((NH4)2SO4) were used as additives to convert the alkali chlorides (mainly KCl) to less corrosive alkali sulphates. Their performance was then evaluated using several measurement tools including, IACM (on-line measurements of gaseous alkali chlorides), a low-pressure impactor (particle size distribution and chemical composition of extracted fly ash particles), and deposit probes (chemical composition in deposits collected). The importance of the presence of either SO2 or SO3 for gas phase sulphation of KCl is also discussed. Ammonium sulphate performed significantly better than elemental sulphur. A more efficient sulphation of gaseous KCl was achieved with (NH4)2SO4 even when the S/Cl molar ratio was less than half compared to sulphur. Thus the presence of gaseous SO3 is of greater importance than that of SO2 for the sulphation of gaseous KCl. © 2010 The Combustion Institute.

Choi H.,University at Albany | Byrne S.,University at Albany | Larsen L.S.,Danish Technological Institute DTI | Sigsgaard T.,University of Aarhus | And 5 more authors.
Indoor Air | Year: 2014

Qualitative reporting of home indoor moisture problems predicts respiratory diseases. However, causal agents underlying such qualitative markers remain unknown. In the homes of 198 multiple allergic case children and 202 controls in Sweden, we cultivated culturable fungi by directly plating dust, and quantified (1-3, 1-6)-β-d-glucan and ergosterol in dust samples from the child's bedroom. We examined the relationship between these fungal agents and degree of parent or inspector-reported home indoor dampness, and microbiological laboratory's mold index. We also compared the concentrations of these agents between multiple allergic cases and healthy controls, as well as IgE-sensitization among cases. The concentrations of culturable fungal agents were comparable between houses with parent and inspector-reported mold issues and those without. There were no differences in concentrations of the individual or the total summed culturable fungi, (1-3, 1-6)-β-d-glucan, and ergosterol between the controls and the multiple allergic case children, or individual diagnosis of asthma, rhinitis, or eczema. Culturable fungi, (1-3, 1-6)-β-d-glucan, and ergosterol in dust were not associated with qualitative markers of indoor dampness or mold or indoor humidity. Furthermore, these agents in dust samples were not associated with any health outcomes in the children. © 2013 John Wiley & Sons A/S.

Karlsson K.,Technical Research Institute of Sweden | Chen X.,Chalmers University of Technology | Kildal P.-S.,Chalmers University of Technology | Carlsson J.,Chalmers University of Technology
IEEE Antennas and Wireless Propagation Letters | Year: 2010

We propose a simple method to accurately predict Doppler spread in a reverberation chamber (RC) by using frequency domainS-parameters measured with a vector network analyzer (VNA) at many fixed stirrer positions (step-wise stationary mode). Thus, the measurements are done under repeatable stationary conditions, so no Doppler shift is present during the actual measurements. Still, this letter shows that the measuredS-parameters in step-wise stationary mode can be used to determine Doppler spread appearing during continuous movement of the stirrers. This can be done by computation for any stirrer speed by assuming that the fixed stirrer position steps are the time steps of a continuous movement of the stirrers, and by adding a virtual stirrer speed between the positions corresponding to the desired continuous movement of the stirrers. The computed Doppler spreads are validated over a large frequency band by measuring the time-varyingS-parameters for a given stirrer speed. © 2006 IEEE.

Hallbjorner P.,Technical Research Institute of Sweden | Sanchez-Heredia J.D.,Technical University of Cartagena | Lindberg P.,TE Connectivity | Martinez-Gonzalez A.M.,Technical University of Cartagena | Bolin T.,Ericsson AB
IEEE Transactions on Antennas and Propagation | Year: 2012

Antenna pairs for diversity or MIMO functionality are characterized under the assumption of a certain statistical distribution of the incident signals over angle and polarization, but also assuming a signal environment with a large number of signal paths. In many real-life environments, however, only a few signal paths contain most of the transferred power. A multipath simulator can be used to realize signal environments with a controlled number of signal paths. This paper presents measurements of dual antenna performance using amultipath simulator with 2-16 signal paths. The results are analyzed in terms of statistical power distributions, power imbalance, correlation coefficient, multiplexing efficiency, and diversity gain. Differences in performance depending on the number of signal paths are noted, illustrating the value of considering the number of signal paths in characterization. © 2011 IEEE.

Choi H.,University at Albany | Schmidbauer N.,Norwegian Institute For Air Research | Bornehag C.-G.,Technical Research Institute of Sweden | Bornehag C.-G.,Karlstad University
Environmental Research | Year: 2016

Background: The question regarding the true sources of the purported microbial volatile organic compounds (MVOCs) remains unanswered. Objective: To identify microbial, as well as non-microbial sources of 28 compounds, which are commonly accepted as microbial VOCs (i.e. primary outcome of interest is σ 28 VOCs). Methods: In a cross-sectional investigation of 390 homes, six building inspectors assessed water/mold damage, took air and dust samples, and measured environmental conditions (i.e., absolute humidity (AH, g/m3), temperature (°C), ventilation rate (ACH)). The air sample was analyzed for volatile organic compounds (μg/m3) and; dust samples were analyzed for total viable fungal concentration (CFU/g) and six phthalates (mg/g dust). Four benchmark variables of the underlying sources were defined as highest quartile categories of: 1) the total concentration of 17 propylene glycol and propylene glycol ethers (σ17 PGEs) in the air sample; 2) 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (TMPD-MIB) in the air sample; 3) semi-quantitative mold index; and 4) total fungal load (CFU/g). Results: Within severely damp homes, co-occurrence of the highest quartile concentration of either σ17 PGEs or TMPD-MIB were respectively associated with a significantly higher median concentration of σ 28 VOCs (8.05 and 13.38 μg/m3, respectively) compared to the reference homes (4.30 and 4.86 μg/m3, respectively, both Ps ≤0.002). Furthermore, the homes within the highest quartile range for σ fungal load as well as AH were associated with a significantly increased median σ 28 VOCs compared to the reference group (8.74 vs. 4.32 μg/m3, P=0.001). Within the final model of multiple indoor sources on σ 28 VOCs, one natural log-unit increase in summed concentration of σ17 PGEs, plus TMPD-MIB (σ 17 PGEs + TMPD-MIB) was associated with 1.8-times (95% CI, 1.3-2.5), greater likelihood of having a highest quartile of σ 28 VOCs, after adjusting for absolute humidity, history of repainting at least one room, ventilation rate, and mold index (P-value =0.001). Homes deemed severely mold damaged (i.e., mold index =1) were associated with 1.7-times (95% CI, 0.8-3.6), greater likelihood of having a highest quartile of σ 28 VOCs, even though such likelihood was not significant (P-value =0.164). In addition, absolute humidity appeared to positively interact with mold index to significantly elevate the prevalence of the highest quartile category of σ 28 VOCs. Conclusion: The indoor concentration of σ 28 VOCs, which are widely accepted as MVOCs, are significantly associated with the markers of synthetic (i.e. σ17 PGEs and TMPD-MIB), and to less extent, microbial (i.e., mold index) sources. © 2016 Elsevier Inc.

Karlsson K.,Technical Research Institute of Sweden | Chen X.,Chalmers University of Technology | Carlsson J.,Technical Research Institute of Sweden | Skarbratt A.,Bluetest
IEEE Antennas and Wireless Propagation Letters | Year: 2013

In this letter, over-the-air (OTA) tests of the performance of the IEEE 802.11p radio system are performed in a reverberation chamber (RC) that is equipped with a fast rotating mode stirrer. By varying the speed of the mode stirrer, different levels of Doppler spreads are created, and the 802.11p radio system is tested accordingly. As expected, the Doppler spread affects the package error rate (PER) of the radio system adversely. In addition to measurements, a simple PER model is presented, which sheds some light into the OTA tests. © 2002-2011 IEEE.

Patel M.,Swedish University of Agricultural Sciences | Sonesson U.,Technical Research Institute of Sweden | Hessle A.,Swedish University of Agricultural Sciences
Animal | Year: 2016

Efficiency in animal protein production can be defined in different ways, for example the amount of human-digestible essential amino acids (HDEAA) in the feed ration relative to the amount of HDEAA in the animal products. Cattle production systems are characterised by great diversity and a wide variety of feeds and feed ration compositions, due to ruminants’ ability to digest fibrous materials inedible to humans such as roughage and by-products from the food and biofuel industries. This study examined the upgrading of protein quality through cattle by determining the quantity of HDEAA in feeds and animal products and comparing different milk and beef production systems. Four different systems for milk and beef production were designed, a reference production system for milk and beef representing typical Swedish production systems today and three alternative improved systems: (i) intensive cattle production based on maize silage, (ii) intensive systems based on food industry by-products for dairy cows and high-quality forage for beef cattle, and (iii) extensive systems based on forage with only small amounts of concentrate. In all four production systems, the quantity of HDEAA in the products (milk and meat) generally exceeded the quantity of HDEAA in the feeds. The intensive production models for beef calves generally resulted in output of the same magnitude as input for most HDEAA. However, in beef production based on calves from dairy cows, the intensive rearing systems resulted in lower output than input of HDEAA. For the extensive models, the amounts of HDEAA in meat were of the same magnitude as the amounts in the feeds. The extensive models with beef calves from suckler cows resulted in higher output in meat than input in feeds for all HDEAA. It was concluded that feeding cattle plants for production of milk and meat, instead of using the plants directly as human food, generally results in an upgrading of both the quantity and quality of protein, especially when extensive, forage-based production models are used. The results imply that the key to efficiency is the utilisation of human-inedible protein by cattle and justifies their contribution to food production, especially in regions where grasslands and/or forage production has comparative benefits over plant food production. By fine-tuning estimation of the efficiency of conversion from human-edible protein to HDEAA, comparisons of different sources of protein production may be more complete and the magnitude of amino acid upgrading in plants through cattle more obvious. © The Animal Consortium 2016

Pinori E.,Technical Research Institute of Sweden | Pinori E.,Gothenburg University | Elwing H.,Gothenburg University | Berglin M.,Technical Research Institute of Sweden | Berglin M.,Gothenburg University
Biofouling | Year: 2013

The efficacy of antifouling coatings designed to minimise the release of biocide, either by embedded (non-covalent) or tethered (covalently bonded) biocides, relies on sufficient bioavailability of the active compound upon contact between the organism and the coating. This investigation is focused on whether coating hardness affects the efficacy of embedded coating systems. Two experimental, non-eroding and waterborne latex paint formulations composed mainly of polystyrene (PS) or polyvinyl versatate (PV) were chosen for their difference in mechanical properties measured in terms of Buchholz indentation resistance. Ivermectin was added to both formulations to a final concentration of 0.1% (w/v) and the steady state release rate was measured according to ISO 15181 at between 34 and 70 ng cm-2 day-1 for both formulations. Field trials conducted over 3 months showed significant differences in anti-barnacle efficacy between the formulations despite their similar release profiles. The softer PV coating showed complete anti-barnacle efficacy, ie no barnacles were detected, while the harder PS coating showed no efficacy against barnacle colonisation during the same time period. The results indicate a new antifouling strategy whereby a route of intoxication is triggered by the organism itself upon interaction with the coating and its embedded biocide. This finding opens new possibilities in controlling macrofouling by low emission antifouling coatings. © 2013 Copyright Taylor and Francis Group, LLC.

Haller M.Y.,University of Applied Sciences Rapperswil | Haberl R.,University of Applied Sciences Rapperswil | Persson T.,Dalarna University | Bales C.,Dalarna University | And 3 more authors.
Energy and Buildings | Year: 2013

Objective For the evaluation of the energetic performance of combined renewable heating systems that supply space heat and domestic hot water for single family houses, dynamic behaviour, component interactions, and control of the system play a crucial role and should be included in test methods. Methods New dynamic whole system test methods were developed based on "hardware in the loop" concepts. Three similar approaches are described and their differences are discussed. The methods were applied for testing solar thermal systems in combination with fossil fuel boilers (heating oil and natural gas), biomass boilers, and/or heat pumps. Results All three methods were able to show the performance of combined heating systems under transient operating conditions. The methods often detected unexpected behaviour of the tested system that cannot be detected based on steady state performance tests that are usually applied to single components. Conclusion Further work will be needed to harmonize the different test methods in order to reach comparable results between the different laboratories. Practice implications A harmonized approach for whole system tests may lead to new test standards and improve the accuracy of performance prediction as well as reduce the need for field tests. © 2013 Elsevier B.V. All rights reserved.

Sjogren T.,Technical Research Institute of Sweden | Wilberfors F.,Scania AB | Alander M.,Technical Research Institute of Sweden
Applied Mechanics and Materials | Year: 2011

Digital image correlation techniques (DIC) have been used in this study to reveal how different phases (graphite, ferrite and pearlite) of compacted graphite cast irons (CGI) accommodate strains at loading. A DIC-software was used to analyse sets of successively acquired images. The images were acquired with a light optical microscope revealing the microstructure of polished and etched CGI materials at different load levels. Five CGI materials, having percentages of pearlite in the range 35 to 90 area%, were included in the study. Apart from the different matrix constituents (ferrite and pearlite) the nodularity was altered and varied from 5% to 65%. It is concluded from this study that the different phases in CGI are affected by the global strain and load to a greater or less extent. The graphite phase appears to accommodate high strains but, due to fracture of the graphite particles at relatively low strains, the resulting high strain values show the opening up of graphite cavities. The ferrite phase is subjected to a strain concentrating effect of the graphite phase and with a low nodularity, i.e., with graphite particles that are stretched out and interconnected, the effect becomes more pronounced resulting in high strains. The pearlitic phase is the strongest of the constituents within the microstructure and the lowest local strains are observed in this phase. The study shows that DIC strain-field images reveal the microstructural strain level distribution for the CGI materials. The future outlook is to use these sets of strain-field images for verification of micro mechanical finite element analysis on a microstructural scale of CGI materials. © (2011) Trans Tech Publications, Switzerland.

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