A System Dynamics Approach to Modeling Temperature Effects in Solid Waste

The amount of municipal solid waste discarded to landfills is continually increasing even with extensive recycling efforts. The need to understand the behavior of waste in landfills is increased due to the decreasing number of active landfills, communities\u27 concern to the potential hazards associated with landfills, and companies or installations with landfills on-site need to understand landfill behavior comply with new legislation concerning design and detecting hazardous material movement of-site. This research is focused on increasing the understanding of landfill behavior by examining the effects of temperature in a landfill system. A system dynamics approach was used in this research to develop and build structure to produce landfill behavior. Two reference modes using gas generation and a basic microbial growth curve were used as verification mechanisms. Initial verification and validation were performed in separate sections then added to Shelley\u27s landfill model to verify that the additional temperature structure more accurately modeled landfill behavior. Results show that an equation responsive to temperature effects on microbial growth and death, more accurately depicts landfill behavior. Increased understanding of how heat is lost from a landfill will increase the usefulness of this model. An inclusive model will help landfill operator\u27s build and manage landfills to Optimize performance and biodegradation over the lifetime of a landfill

Connecting Abaqus and CATIA V5 in product development

Abstract. In this work Abaqus software, which is used for doing finite element analysis, and the associative interface of CATIA V5 computer-aided design software and Abaqus were researched. From the associative interface, the usage with Abaqus and the usage’s requirements were researched. From Abaqus it’s usage and requirements were studied. The software was also explored by a case study. In the case study there was no need to utilize the associativity of the associative interface. The methods of research in this work were computer-aided design, finite element analysis and the connection of those through associative interface. In this work it was clarified how the associative interface works with Abaqus by the features, and how Abaqus works by its modules. This work included a case study, in which squeezing of a cavity seal between two plastic shells was simulated. In the case study nonlinear material model for the cavity seal was used. The case study was challenging due high nonlinearity and included especially calculation time challenges. In the case study a situation occurred where the simulation did not pass every step. Because of that a decision was made to make a second finite element analysis model, where the cavity seal model was replaced by gasket model that was simpler in terms of the calculations. The old model was named as model A and the new model as model B. In case study’s results models A and B were compared, and represented shell’s strains and stress of screw towers were calculated by model B. In the work’s discussion the benefits of associative interface with Abaqus were discussed together with an export problem which appeared during the work, a need of expert for making simulations and the change of gasket model in the case study. As conclusions it was stated of the associative interface that its very useful with Abaqus, and it does not need special skills or experience for the use. However, as a conclusion it was stated that training is needed for use of Abaqus.Abaqus ja CATIA V5 -ohjelmistojen yhdistäminen tuotekehityksessä. Tiivistelmä. Tässä työssä tutkittiin Dassault Systémesin Abaqus-ohjelmaa, jolla tehdään elementtianalyyseja sekä CATIA V5 -tietokoneavusteisen suunnitteluohjelman ja Abaquksen välistä assosiatiivista käyttöliittymää. Assosiatiivisesta käyttöliittymästä tutkittiin yhteiskäyttöä Abaquksen kanssa, ja yhteiskäytön vaatimuksia. Abaquksesta tutkittiin käyttöä ja käytön vaatimuksia. Ohjelmistoon tutustuttiin myös esimerkkitapauksen avulla. Tässä esimerkkitapauksessa ei tarvinnut hyödyntää assosiatiivisen käyttöliittymän assosiatiivisuutta. Käytettävät tutkimusmenetelmät työssä olivat tietokoneavusteinen suunnittelu, elementtianalyysi, ja tietokoneavusteisen suunnittelun ja elementtianalyysin yhdistäminen. Työssä selvitettiin, miten assosiatiivinen käyttöliittymä toimii Abaquksen kanssa ominaisuuksittain ja miten Abaqus toimii moduuleittain. Lisäksi työ sisälsi esimerkkitapauksen, jossa simuloitiin ontelotiivisteen puristusta kahden muovikuoren väliin. Esimerkkitapauksessa käytettiin epälineaarista materiaalimallia ontelotiivisteelle. Tämä esimerkkitapaus oli vaativa ja sisälsi erityisesti laskenta-aikahaasteita. Esimerkkitapauksessa päädyttiin tilanteeseen, jossa simulaatio ei mennyt kaikkein vaiheiden läpi. Tämän takia päädyttiin tekemään toinenkin elementtianalyysimalli, jossa ontelotiivistemalli oli korvattu laskennan kannalta yksinkertaisemmalla tiivistemallilla. Vanha malli nimettiin malli A:ksi, ja uusi malli nimettiin malli B:ksi. Esimerkkitapauksen tuloksissa vertailtiin malleja A ja B, ja otettiin esiin mallilla B laskettuja kuorten venymiä ja ruuvitornien jännitystiloja. Työn käsittelyosuudessa käsiteltiin assosiatiivisen käyttöliittymän hyötyjä Abaquksen kanssa, työtä tehdessä ilmenneeseen tiedonvienti ongelmaan, asiantuntijan tarvetta esimerkkitapauksen simulaatiota tehdessä ja tiivistemallin vaihtoa työssä. Johtopäätöksinä assosiatiivisesta käyttöliittymästä todettiin, että se on Abaquksen kanssa hyvin käyttökelpoinen, eikä tarvitse erikoisosaamista tai -kokemusta käyttöä varten. Johtopäätöksenä Abaquksesta todettiin, että se tarvitsee käyttöä varten kouluttautumista

Loss of density-dependence and incomplete control by dominant breeders in a territorial species with density outbreaks

<p>Abstract</p> <p>Background</p> <p>A territory as a prerequisite for breeding limits the maximum number of breeders in a given area, and thus lowers the proportion of breeders if population size increases. However, some territorially breeding animals can have dramatic density fluctuations and little is known about the change from density-dependent processes to density-independence of breeding during a population increase or an outbreak. We suggest that territoriality, breeding suppression and its break-down can be understood with an incomplete-control model, developed for social breeders and social suppression.</p> <p>Results</p> <p>We studied density dependence in an <it>arvicoline </it>species, the bank vole, known as a territorial breeder with cyclic and non-cyclic density fluctuations and periodically high densities in different parts of its range. Our long-term data base from 38 experimental populations in large enclosures in boreal grassland confirms that breeding rates are density-regulated at moderate densities, probably by social suppression of subordinate potential breeders. We conducted an experiment, were we doubled and tripled this moderate density under otherwise the same conditions and measured space use, mortality, reproduction and faecal stress hormone levels (FGM) of adult females. We found that mortality did not differ among the densities, but the regulation of the breeding rate broke down: at double and triple densities all females were breeding, while at the low density the breeding rate was regulated as observed before. Spatial overlap among females increased with density, while a minimum territory size was maintained. Mean stress hormone levels were higher in double and triple densities than at moderate density.</p> <p>Conclusions</p> <p>At low and moderate densities, breeding suppression by the dominant breeders, But above a density-threshold (similar to a <it>competition point</it>), the dominance of breeders could not be sustained (<it>incomplete control</it>). In our experiment, this point was reached after territories could not shrink any further, while the number of intruders continued to increase with increasing density. Probably suppression becomes too costly for the dominants, and increasing number of other breeders reduces the effectiveness of threats. In wild populations, crossing this threshold would allow for a rapid density increase or population outbreaks, enabling territorial species to escape density-dependency.</p

Which probes are most useful when undertaking cognitive interviews?

This paper reports the use of verbal probes in cognitive interviews (CIs) undertaken to test the usefulness, validity and reliability of survey questions. Through examining the use of probes by three interviewers undertaking interviews as part the piloting of a cross-national crime survey, we examine which of the various types of probes used in CIs produce the most useful information. Other influences on interview quality are examined, including differences between interviewers and respondents themselves. The analyses rely on multi-level modelling and suggest that anticipated, emergent and conditional probes provide the most useful data. Furthermore, age, gender and educational levels appear to have no bearing on the quality of the data generated

RFQ-cooler for low-energy radioactive ions at ISOLDE

A radio frequency ion cooler and buncher project at the CERN-ISOLDE facility is presented. Monte Carlo simulations, based on the ion mobility concept will be discussed. Future options for the facility are outlined