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- Bennitz, Anders, et al.
(författare)
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Dynamic behaviour of the Vindel River railway bridge
- 2006
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Ingår i: Condition Monitoring and Diagnostic Engineering Management. - Luleå : Luleå tekniska universitet. - 9789163188060 ; , s. 721-729
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Konferensbidrag (refereegranskat)abstract
- The Swedish Railway administration has launched several projects aimed at increasing the accessibility of the railway lines in northern Sweden to meet future demands. One of these lines connects the southern and northern parts of Sweden and constitutes one of the major arteries for the transportation of heavy goods. Major investment are planned to upgrade the load bearing capacity of this railway line. The work is mainly focused on the larger structures and their dynamical properties. These properties can be used to assess existing infrastructure and to evaluate the performance. Advantages are obvious since the existing structural integrity form the base for investments in structural repair and upgrade of bridges. The Vindel River Railway Bridge situated 55 kilometers northwest of Umeå came into focus when large motion was discovered during train passages. The behaviour of the bridge crossing the river of Vindeln has been measured two times. Measurements of displacements and acceleration of the bridge during train passages has been conducted, the first measurements was done to give more experience on the motion of the bridge and to try out new sensors. The second measurement gave more information about the bridge's motion, results that could be used to calibrate a 3D FE-Model of the bridge used in the study. Based on the measurements, eigenfrequencies in the range of 0 to 8 Hz could be detected, modal shapes up to the ninth order could be extracted, deflections and transverse displacements for different sets of train and different train speeds were also found. However, new measurements are planned for this summer and will hopefully reinforce the already attained result and give answers to some of the unresolved questions.
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| 7. |
- Gonzalez, Helena, 1971, et al.
(författare)
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Photostability of commercial sunscreens upon sun exposure and irradiation by ultraviolet lamps
- 2007
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Ingår i: BMC Dermatol. - 1471-5945. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Sunscreens are being widely used to reduce exposure to harmful ultraviolet (UV) radiation. The fact that some sunscreens are photounstable has been known for many years. Since the UV-absorbing ingredients of sunscreens may be photounstable, especially in the long wavelength region, it is of great interest to determine their degradation during exposure to UV radiation. Our aim was to investigate the photostability of seven commercial sunscreen products after natural UV exposure (UVnat) and artificial UV exposure (UVart). METHODS: Seven commercial sunscreens were studied with absorption spectroscopy. Sunscreen product, 0.5 mg/cm2, was placed between plates of silica. The area under the curve (AUC) in the spectrum was calculated for UVA (320-400 nm), UVA1 (340-400 nm), UVA2 (320-340 nm) and UVB (290-320 nm) before (AUCbefore) and after (AUCafter) UVart (980 kJ/m2 UVA and 12 kJ/m2 of UVB) and before and after UVnat. If theAUC Index (AUCI), defined as AUCI = AUCafter/AUCbefore, was > 0.80, the sunscreen was considered photostable. RESULTS: Three sunscreens were unstable after 90 min of UVnat; in the UVA range the AUCI was between 0.41 and 0.76. In the UVB range one of these sunscreens was unstable with an AUCI of 0.75 after 90 min. Three sunscreens were photostable after 120 min of UVnat; in the UVA range the AUCI was between 0.85 and 0.99 and in the UVB range between 0.92 and 1.0. One sunscreen showed in the UVA range an AUCI of 0.87 after UVnat but an AUCI of 0.72 after UVart. Five of the sunscreens were stable in the UVB region. CONCLUSION: The present study shows that several sunscreens are photounstable in the UVA range after UVnat and UVart. There is a need for a standardized method to measure photostability, and the photostability should be marked on the sunscreen product.
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- Ostman, M., et al.
(författare)
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Leachability and metal-binding capacity in ageing landfill material
- 2008
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Ingår i: Waste Management. - : Elsevier BV. - 0956-053X .- 1879-2456. ; 28:1, s. 142-150
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Tidskriftsartikel (refereegranskat)abstract
- In order to study the stability of landfilled heavy metals, landfill material from a combined household and industrial waste landfill was aerated for 14 months to simulate the natural ageing processes as air slowly begins to penetrate the landfill mass. During aeration, the pH of the landfill material decreased from around 8.6 to 8.1 and the carbon content also decreased. In order to investigate the possible fate of metals in ageing landfills, a four-stage sequential extraction technique was applied. The ability of the materials to bind metal ions by electrostatic attractions and to form stronger complexes was studied separately. The amount of exchangeable cations, the capacity to bind metal ions by electrostatic attraction and the capacity of the landfill material to complex copper ions were increased by the aeration process. However, results from the sequential analysis showed an increased solubility of sulphur and some metals (Cd, Co, Cu, Ni and Zn). Equilibrium speciation models (Medusa) indicated that the organic matter deposit had a significant capacity to bind metal ions provided that pH was sufficiently high. However, as carbonates are consumed over time, the risk for metal mobility increases. Therefore, the landfills can become an environmental risk, depending on variations in the solubility of metal ions due to changes in pH, redox status and the availability of organic material.
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| 12. |
- Pernestål, A., et al.
(författare)
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A Bayesian approach to fault isolation - Structure estimation and inference
- 2007
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Konferensbidrag (refereegranskat)abstract
- This chapter considers a Bayesian inference method for fault isolation. Given a set of residuals, and a set of possible faults, the task is to calculate the probability distribution of the faults. The method requires conditional probability distribution of how the residuals respond given the possible faults. Especially important is to know the structure of this conditional probability distribution, since it facilitates the use of efficient Bayesian network techniques for the inference. The conditional probability distribution, and in particular its structure, is estimated from training data using a Bayesian approach. The approach is evaluated on a simple but illustrative example, where it is shown that the estimated structure and the distributions capture the dependencies that are important to make the correct isolation decisions.
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- Wahlberg, Bo, 1959-, et al.
(författare)
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Experiences from subspace system identification - Comments from process industry users and researchers
- 2007
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Ingår i: MODELING, ESTIMATION AND CONTROL. - BERLIN : SPRINGER-VERLAG BERLIN. - 9783540735694 ; , s. 315-327
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Konferensbidrag (refereegranskat)abstract
- Subspace System Identification is by now an established methodology for experimental modelling. The basic theory is well understood and it is more or less a standard tool in industry. The two main research problems in subspace system identification that have been studied in the recent years are closed loop system identification and performance analysis. The aim of this contribution is quite different. We have asked an industrial expert working in process control a set of questions on how subspace system identification is used in design of model predictive control systems for process industry. As maybe expected, it turns out that a main issue is experiment/input design. Here, the difference between theory and practice is rather large mainly due to implementation constraints, but also lack of knowledge transfer. Motivated by the response from the expert, we will discuss several important user choices problems, such as optimal input design, merging of data sets and merging of models.
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- Wahlberg, Olof, et al.
(författare)
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How a Medium Sized Enterprise Applies the CRM Approach in its Marketing
- 2009
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Ingår i: Proceedings of the 3rd European Conference on Information Management and Evaluation. - : Academic Conferences Limited. - 9781906638443 - 9781906638436 ; , s. 448-459
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Konferensbidrag (refereegranskat)abstract
- The purpose is to describe how a medium sized enterprise with an international scope, positive economic development, and relatively high ICT maturity applies the CRM approach in its marketing. Medium sized enterprises with these features are assumed to be role models for smaller enterprises, and in particular for smaller enterprises with growth ambitions. This case study is based on structured interviews conducted with the CEO and the manager responsible for IT and IS development in the enterprise. The findings show that the enterprise endorses a customer-oriented business strategy, supported by fairly simple information gathering and analysing methods; that the dependency on agents and dealers is a problem in an CRM perspective; and that the development of the Web offers new possibilities for CRM practices and policies.
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- Östman, M, et al.
(författare)
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Metal and organic matter contents in a combined household and industrial landfill
- 2006
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Ingår i: Waste Management. - : Elsevier BV. - 0956-053X .- 1879-2456. ; 26:1, s. 29-40
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Tidskriftsartikel (refereegranskat)abstract
- A combined household/industrial landfill in a humid and cold temperate climate was characterised with respect to its chemical composition. Cores taken at three randomly chosen sites on the landfill and at different depths at each site were analysed. Carbon, nitrogen and pH were measured by standard laboratory methods. The chemical elements analysed included metals and the non-metals B, P and S. pH ranged between 8.0 and 8.5. The total carbon content was in the interval 4.5-26.9% and the total nitrogen content in the interval 0.05-0.48%. The C/N ratio was high, indicating that there was not enough nitrogen available to ensure the stabilisation of carbon. The metal contents varied substantially. The water and carbon contents were related to each other as well as to the metal content, which increased with the content of water. Based on the results obtained regarding the chemical composition of the landfill, it is evident that the landfill consists of two layers. This indicates that the landfill body might have different levels of chemical development, due to water content, and different long-term leachability in the future.
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