Characterization of residential chimney conditions for flue gas flow measurements

A literature survey and a theoretical study were performed to characterize residential chimney conditions for flue gas flow measurements. The focus is on Pitot-static probes to give sufficient basis for the development and calibration of a velocity pressure averaging probe suitable for the continuous dynamic (i.e. non steady state) measurement of the low flow velocities present in residential chimneys. The flow conditions do not meet the requirements set in ISO 10780 and ISO 3966 for Pitot-static probe measurements, and the methods and their uncertainties are not valid. The flow velocities in residential chimneys from a heating boiler under normal operating condi-tions are shown to be so low that they in some conditions result in voiding the assumptions of non-viscous fluid justifying the use of the quadratic Bernoulli equation. A non-linear Reynolds number dependent calibration coefficient that is correcting for the viscous effects is needed to avoid significant measurement errors. The wide range of flow velocity during normal boiler operation also results in the flow type changing from laminar, across the laminar to turbulent transition region, to fully turbulent flow, resulting in significant changes of the velocity profile during dynamic measurements. In addition, the short duct lengths (and changes of flow direction and duct shape) used in practice are shown to result in that the measurements are done in the hydrodynamic entrance region where the flow velocity profiles most likely are neither symmetrical nor fully developed. A measurement method insensitive to velocity profile changes is thus needed, if the flow velocity profile cannot otherwise be determined or predicted with reasonable accuracy for the whole measurement range. Because of particulate matter and condensing fluids in the flue gas it is beneficial if the probe can be constructed so that it can easily be taken out for cleaning, and equipped with a locking mechanism to always ensure the same alignment in the duct without affecting the calibration. The literature implies that there may be a significant time lag in the measurements of low flow rates due to viscous effects in the internal impact pressure passages of Pitot probes, and the significance in the discussed application should be studied experimentally. The measured differential pressures from Pitot-static probes in residential chimney flows are so low that the calibration and given uncertainties of commercially available pressure transducers are not adequate. The pressure transducers should be calibrated specifically for the application, preferably in combination with the probe, and the significance of all different error sources should be investigated carefully. Care should be taken also with the temperature measurement, e.g. with averaging of several sensors, as significant temperature gradients may be present in flue gas ducts.

Film som kommunikation : En studie av gymnasieungdomars filmarbete

The starting point for this work was a discussion between my supervisor and myself during my teaching training. The discussion concerned the appropriateness of allowing students make films with sexual content. Film gives young people the opportunity to express their feelings and broaden their views. If the film then disseminates to unknown people via in-ternet, which it most likely will do, maybe it is no longer so positive. The aim of this study is to shed light on various aspects of identity and ethics that are important to keep in mind when young people in school make films. These aspects are to avoid making young people vulnerable to abuse and improper influence. One aim is also to highlight the advantages of making films in school. The study is inspired by hermeneutic interpretive and based on qualitative interviews. The informants are four students at the age of 18-19 at two different schools in one municipality in Sweden.The results of the study show that it is important for the informants that the films are pro-duced in an aesthetically good way so that it appeals to the audience. Two of the infor-mants have a specific audience and make more conscious choices, so that the audience will understand what is said. The study shows that the more a filmmaker considers the audi-ence, the more consciously he or she uses film as communication. To get positive feedback is important, but it is mostly friends of the filmmakers that actually comment. To get nega-tive comments is regarded as a disadvantage when placing material on the internet. Howev-er, none of the informants in the study have received negative comments on what has been posted. The opinions about what the informants believe is inappropriate to post on inter-net or to make films about regards sexuality and violations. Earlier studies show that mate-rial can, because it is interesting to other people, become widespread. For this reason it is important for teachers to have conversations with students about their preferences and opinions on various issues. Adults need to interfere in the young people's world, while be-ing open to their opinions. Then the young people's value system will be built up and give them a safe tool that helps them to avoid improper influence.

A systematic review of triage-related interventions to improve patient flow in emergency departments

Background Overcrowding in emergency departments is a worldwide problem. A systematic literature review was undertaken to scientifically explore which interventions improve patient flow in emergency departments. Methods A systematic literature search for flow processes in emergency departments was followed by assessment of relevance and methodological quality of each individual study fulfilling the inclusion criteria. Studies were excluded if they did not present data on waiting time, length of stay, patients leaving the emergency department without being seen or other flow parameters based on a nonselected material of patients. Only studies with a control group, either in a randomized controlled trial or in an observational study with historical controls, were included. For each intervention, the level of scientific evidence was rated according to the GRADE system, launched by a WHO-supported working group. Results The interventions were grouped into streaming, fast track, team triage, point-of-care testing (performing laboratory analysis in the emergency department), and nurse-requested x-ray. Thirty-three studies, including over 800,000 patients in total, were included. Scientific evidence on the effect of fast track on waiting time, length of stay, and left without being seen was moderately strong. The effect of team triage on left without being seen was relatively strong, but the evidence for all other interventions was limited or insufficient. Conclusions Introducing fast track for patients with less severe symptoms results in shorter waiting time, shorter length of stay, and fewer patients leaving without being seen. Team triage, with a physician in the team, will probably result in shorter waiting time and shorter length of stay and most likely in fewer patients leaving without being seen. There is only limited scientific evidence that streaming of patients into different tracks, performing laboratory analysis in the emergency department or having nurses to request certain x-rays results in shorter waiting time and length of stay.

Har den interna demokratin i politiska partier försämrats över tid?

Has intra-party democracy deteriorated over time? A widely held view in contemporary party research is that intra-party democracy, especially in traditional mass parties, has deteriorated in the age of the cartel party. This common assessment, however, relies on insufficient empirical evidence, and is scrutinized in the article. The notion of a gradual progress towards the cartel party implicitly shares common characteristics with the classic theory of Michels. In order to investigate the actual fate of intra-party democracy, central aspects of Michels theory are explored over time in a critical case, namely the Swedish SAP. If intra-party democracy is declining, this tendency should be most likely to be observed in this case. Two internal decision-making processes, surrounding two major pension reforms – one expansion in the 1950’s and one retrenchment in the 1990’s – are compared based on criteria deducted from Michels. Instead of finding a decline in intraparty democracy, the results conclusively demonstrate major improvements.

Design and validation of a sheet metal shearing experimental procedure

Throughout the industrial processes of sheet metal manufacturing and refining, shear cutting is widely used for its speed and cost advantages over competing cutting methods. Industrial shears may include some force measurement possibilities, but the force is most likely influenced by friction losses between shear tool and the point of measurement, and are in general not showing the actual force applied to the sheet. Well defined shears and accurate measurements of force and shear tool position are important for understanding the influence of shear parameters. Accurate experimental data are also necessary for calibration of numerical shear models. Here, a dedicated laboratory set-up with well defined geometry and movement in the shear, and high measurability in terms of force and geometry is designed, built and verified. Parameters important to the shear process are studied with perturbation analysis techniques and requirements on input parameter accuracy are formulated to meet experimental output demands. Input parameters in shearing are mostly geometric parameters, but also material properties and contact conditions. Based on the accuracy requirements, a symmetric experiment with internal balancing of forces is constructed to avoid guides and corresponding friction losses. Finally, the experimental procedure is validated through shearing of a medium grade steel. With the obtained experimental set-up performance, force changes as result of changes in studied input parameters are distinguishable down to a level of 1%.