Abstract Increasing environmental and economic awareness are driving the development of combustion technologies to efficient biomass use and clean burning. To accomplish these goals, quantitative information about combustion variables is needed. However, for small-scale combustion units the existing monitoring methods are often expensive or complex. This study aimed to quantify correlations between flue gas temperatures and combustion variables, namely typical emission components, heat output, and efficiency. For this, data acquired from four small-scale combustion units and a large circulating fluidised bed boiler was studied. The fuel range varied from wood logs, wood chips, and wood pellets to biomass residue. Original signals and a defined set of their mathematical transformations were applied to data analysis. In order to evaluate the strength of the correlations, a multivariate distance measure based on information theory was derived. The analysis further assessed time-varying signal correlations and relative time delays. Ranking of the analysis results was based on the distance measure. The uniformity of the correlations in the different data sets was studied by comparing the 10-quantiles of the measured signal. The method was validated with two benchmark data sets. The flue gas temperatures and the combustion variables measured carried similar information. The strongest correlations were mainly linear with the transformed signal combinations and explicable by the combustion theory. Remarkably, the results showed uniformity of the correlations across the data sets with several signal transformations. This was also indicated by simulations using a linear model with constant structure to monitor carbon dioxide in flue gas. Acceptable performance was observed according to three validation criteria used to quantify modelling error in each data set. In general, the findings demonstrate that the presented signal transformations enable real-time approximation of the studied combustion variables. The potentiality of flue gas temperatures to monitor the quality and efficiency of combustion allows development toward cost effective control systems. Moreover, the uniformity of the presented signal correlations could enable straightforward copies of such systems. This would cumulatively impact the reduction of emissions and fuel consumption in small-scale biomass combustion. / Tiivistelmä Kasvava ympäristö- ja kustannustietoisuus ohjaa polttoteknologioiden kehitystä yhä tehokkaampaan biomassan hyödyntämiseen ja puhtaampaan palamiseen. Näiden tavoitteiden saavuttamiseen tarvitaan mittaustietoa palamismuuttujista. Nykyiset palamisen seurantaan tarkoitetut ratkaisut ovat kuitenkin pienpolttolaitteita ajatellen usein kalliita tai monimutkaisia. Tässä työssä tutkittiin mitattujen savukaasun lämpötilojen riippuvuussuhdetta tyypillisiin kaasukomponentteihin, lämpötehoon ja tehokkuuteen. Tätä varten analysoitiin mittausaineistot neljästä erityyppisestä pienpolttolaitteesta ja suuresta kiertoleijupeti-kattilasta. Puupolttoaineina olivat klapi, hake, pelletti ja hakkuujäte. Analyysi tehtiin alkuperäisillä mittaussignaaleilla ja niistä matemaattisesti muunnetuilla signaaleilla. Riippuvuussuhteiden selvittämiseksi johdettiin informaatioteoriaan perustuva monimuuttuja-etäisyysmitta, jonka lukuarvolla mitataan signaalien samankaltaisuutta. Esitetty analyysimenetelmä sisälsi myös riippuvuuksien ajallisen muutoksen ja suhteellisten aikaviiveiden arvioinnin. Tulosten arvojärjestys perustui etäisyysmitan arvoon. Riippuvuussuhteiden samankaltaisuutta mittausaineistojen välillä vertailtiin 10-kvantiileilla. Analyysimenetelmän toimivuus vahvistettiin kahdella tunnetulla koeaineistolla. Savukaasun lämpötilojen ja palamismuuttujien mittaussignaaleissa oli samankaltainen informaatiosisältö. Vahvimmat riippuvuudet olivat muunnettujen signaalien yhdistelmillä pääosin lineaarisia ja palamisteorian mukaisia. Merkittävää oli, että tietyillä signaalimuunnos- ja palamismuuttujapareilla oli sama riippuvuussuhde kaikissa mittausaineistossa. Tämä todettiin myös simuloinneilla arvioitaessa savukaasujen hiilidioksidipitoisuutta lineaarisella, kiinteällä mallirakenteella. Mallin tarkkuus oli riittävä kolmella erityyppisellä kriteerillä jokaisessa mittausaineistossa. Tulosten perusteella signaalimuunnoksilla voidaan arvioida palamismuuttujia reaaliaikaisesti. Savukaasujen lämpötilojen potentiaali palamisen laadun ja tehokkuuden seurannassa mahdollistaa kustannustehokkaiden säätöratkaisujen kehityksen. Löydettyjä yleistettäviä riippuvuussuhteita hyödyntämällä niiden käyttöönotto lukuisissa polttolaitteissa helpottuisi. Pienpolton päästöjen ja polttoaineen kulutuksen vähentyminen olisi tällöin kumulatiivista.

Malaise traps are a common tool for collecting insects used by many researchers. Although there have been variations in the models and materials used for Malaise traps, the potential for sampling bias due to mesh gague has been explored inadequately. This study compared coarse and fine mesh Townes model Malaise traps in two habitats on the Grand Staircase-Escalante National Monument. The two habitats next to the Lick Wash trailhead were defined by dominant vegetation type – sagebrush and grasses or Piñon-Juniper. We collected from three sites per habitat type, over three consecutive days in June in both 2006 and 2007. A pair of Malaise traps consisting of one coarse mesh and one fine mesh trap were used at each site in order to compare differences in the diversity and in the average size of individuals collected by each type of Malaise trap. We measured diversity using both presence-absence data such as richness scores and Jaccard's Index of Similarity, and abundance-based measures of comparison, including Simpson's Index of Diversity and non-metric multidimensional scaling. We identified all individuals according to Order, and because of our interest in flies and their abundance, we further identified the Dipter ta to the Family level. Average insect size was determined by categorizing individuals according to one of 14 distinct size-classes. In sum, 71 samples totaling approximately 62,500 insects were identified and sized. Because we sampled from two adjacent habitats, we also discuss beta diversity across the sample sites. Although mesh-size appears to have a significant effect on the diversity of the catch according to some tests, not all of our analysis agrees. In addition, the gain in the amount of diversity collected by incorporating both mesh-sizes may not be worth the costs of that kind of sampling. Other means of collection may adequately make up that difference. Habitat on the other hand was a clear marker for difference in diversity. Size was not found to be significant overall, but there still may be reasons to examine the effect of mesh-size with respect to the Hymenoptera.