1,041 research outputs found
An Assessment of Avian Populations Within the FAP 431 Project Area, Cook, Dupage, and Will Counties, Illinois
Final Report, issued June, 1989Report issued on: June 1989INHS Technical Report prepared for Ilinois Department of Transportation, Bureau of
Location and Environmen
DIFFUSION OF CASE: An obstacle race?
This paper provides a conceptual and discussion framework for answering what the obstacles to diffusion of CASE-technology may be. CASE is viewed in a tool-external context and with focus on the negative aspects of CASEtechnology, as the goal is to discuss the obstacles to diffusion of CASE. The paper is mainly based on literature reviews and serves as a point of departure for further empirical research.
Application of CASE-tools has consequences for the individual work process of the systems developers and for the roles of the development team members. These consequences may cause resistance against the use of CASE-tools. Successful use of CASE-tools is also determined by the basic approach to development of software. Moreover CASE-tools influence the communication between developers and end-users. Increased quality of design and productivity of the development process depend on correctly understanding of the requirements, which reflects the quality of this communication.
An important condition of diffusion is solving of the so-called software crisis: lack of productivity and quality increases of software development. Productivity and quality increases necessitate efforts in the initial development phases and better support of the user-developer communication. These are areas, which are not seriously improved by the application of CASE-tools
Is signal crayfish (Pacifastacus leniusculus) able to biologically control the invasive zebra mussel (Dreissena polymorpha)?
The aim of this study was to collect new knowledge about the importance of signal crayfish predation on zebra mussels in Lake Erken. Possibly with implications on biological control of the invasive species in Swedish lakes. I performed a field experiment with enclosures (including signal crayfish) and exclosures (without signal crayfish) during 11 summer weeks in Lake Erken. My results showed that signal crayfish can significantly reduce the abundance of zebra mussels. I conclude that signal crayfish is able to affect a population of zebra mussel, but further research is needed to know by which mechanism: do signal crayfish exert an effective predation pressure on zebra mussels or have the invasive species already evolved an effective avoidance behavior towards signal crayfish?Aliens i sjön Erken! Kontrolleras av glupska kannibaler? Det finns aliens i sjön Erken. Nej inte utomjordingar, utan en mussla som inte hör hemma där egentligen. På engelska kallas det en ”alien species” när arten har flyttats till ett ställe där den inte finns naturligt. Denna mussla har ett randigt mönster på skalet och kallas därför zebramussla. Eftersom den är så bra på att sprida sig kallas den också vandrarmussla. I USA och Kanada har musslorna ställt till stora problem när de t.ex. har satt sig fast i vattenrör till/från fabriker. I Sverige har deras vassa skalkanter skurit upp fötter på badande när de försökt stå på de musselbeklädda bottenstenarna. Vattenmyndigheterna är dessutom rädda att zebramusslorna ska utrota de musslor som har funnits här under längre tid. Zebramusslorna sätter sig fast utanpå skalet på större musslor och hindrar dem från att röra sig och från att filtrera i sig mat. Vem ska då rädda oss från dessa aliens? Kanske ett gäng glupska kannibaler? Signalkräftor äter allt, bland annat andra signalkräftor. De bor också i sjön Erken. Tidigare forskning i akvarier har visat att kräftorna kan äta upp zebramusslor. Jag var nyfiken på hur det fungerade i verkligheten, i sjön. Därför snickrade jag ihop tio burar som sänktes ner i sjön under drygt 11 sommarveckor 2005. Alla burar innehöll cement-takpannor som zebramusslorna skulle sätta sig fast på. Hälften av burarna innehöll även kräftor. När burarna togs upp räknades hur många zebramusslor som fanns på pannorna som kräftorna kunnat äta på. Det jämfördes med hur många zebramusslor som fanns på kontroll-pannorna: Väsentligt många fler zebramusslor fanns i kontroll-burarna än i kräft-burarna! Kan det vara så att signalkräftorna håller zebramusslorna under kontroll i sjön Erken? Eller har zebramusslorna hittat ett sätt att fly fältet? Kommer signalkräftorna att välja zebramussel-mat när det också finns goda snäckor i sjön? Mina resultat har gjort det tydligt att signalkräftan påverkar zebramusslan. Men för att förstå om detta är ett lämpligt sätt att kontrollera den problemskapande zebramusslan, behövs vidare studier. Gärna filmade beteende-studier i sjön: ”Aliens vs. Cannibals – the battle of Lake Erken”. Handledare: Eva Waldemarsson (Kajsa Åbjörnsson, Per Nyström) Examensarbete i Limnologi 30 hp 2015 Biologiska institutionen, Lunds universite
A finite element based design tool for point fixed laminated glass
In this master’s project, a design tool for bolt fixed laminated glass was developed, based on linear-elastic finite element theory. The program produces images of the deflections and stress distributions in bolted glass panes. A two-dimensional triangular mesh, created by an external mesh generator, was extended to a three-dimensional mesh comprising 15-node wedge elements. A least-square method was adopted for extrapolating stresses from Gaussian sample points to the element nodes. A simple graphical user interface was developed in the programming language Python, as well as a simple post-processor employing the graphics library OpenGL
The Influence of End- and Edge Distances on the Load-Carrying Capacity in Joints with Inclined Screws.
Using an inclined screw brings many advantages compared to traditional methods, e.g. high load-bearing capacity, fast and easy montage and high fire resistance. This report contains a study of the influence end- and edge distances have on the load-carrying capacity in joints with inclined screws. Tests were carried out in order to determine if a few of the end- and edge distances proposed by Kevarinmäki is too conservative. Further, withdrawal tests in slender construction timber were made, in order to determine if the SFS WT-T 8,2x300 screw is suitable in roof truss connections
Analysis and Design of Hybrid Control Systems
Different aspects of hybrid control systems are treated: analysis, simulation, design and implementation. A systematic methodology using extended Lyapunov theory for design of hybrid systems is developed. The methodology is based on conventional control designs in separate regions together with a switching strategy. Dynamics are not well defined if the control design methods lead to fast mode switching. The dynamics depend on the salient features of the implementation of the mode switches. A theorem for the stability of second order switching together with the resulting dynamics is derived. The dynamics on an intersection of two sliding sets are defined for two relays working on different time scales. The current simulation packages have problems modeling and simulating hybrid systems. It is shown how fast mode switches can be found before or during simulation. The necessary analysis work is a very small overhead for a modern simulation tool. To get some experience from practical problems with hybrid control the switching strategy is implemented in two different software environments. In one of them a time-optimal controller is added to an existing PID controller on a commercial control system. Successful experiments with this hybrid controller shows the practical use of the method
An investigation of the learning needs of expectant parents
Thesis (M.S.)--Boston Universit
Anthropogenic influence on new particle formation in the marine boundary layer atmosphere
The most important parameter for estimates of the anthropogenic induced climate change is the radiative forcing. In a comparison of the earth’s radiative budget in the year 2011 relative to 1750, the intergovernmental panel on climate change concludes that the largest uncertainty in the total radiative forcing derives from aerosol particles and their ability to modify cloud properties as cloud condensation nuclei (CCN). This uncertainty may be reduced from increased knowledge of the spatial and temporal distribution of aerosol particles with CCN properties. In this project, aerosol particles formed in coastal and marine atmospheres through so called new particle formation (NPF) were analysed spatially and temporally and an assessment of the anthropogenic impact on the marine NPF was attempted. A method known as the NanoMap method was applied to infer the frequency of NPF in marine environments in the North Sea, Baltic Sea and the Mediterranean Sea. The results of the NanoMap analysis clearly identifies NPF frequently occurring in all three marine environments. The results suggested furthermore an increased probability of NPF in areas with heavy shipping. If the particles formed by the NPF grow to sizes with diameters larger than 50 nm, these may participate in the formation of clouds as CCN. To assess the anthropogenic impact on marine NPF, aerosol properties and NPF were simulated with the ADCHEM model. The input gas phase emissions to the model were emissions from anthropogenic, biogenic and natural sources. The simulations were carried out mainly over the the North Sea and the model was evaluated against the total particle volume measured in Høvsøre, Denmark. The model results were reasonably consistent with the observations. From the ADCHEM modelling results, it was concluded that anthropogenic marine emissions do influence NPF. The modelled particle size distribution at Høvsøre showed evidence of an increase in the NPF most likely as a result of anthropogenic emissions of condensable gases. However, particulate matter from shipping emissions were in some cases found to suppress the NPF. It was therefore concluded that new marine emission control legislations of sulphur-containing compounds may result in a decrease of marine NPF. If particulate emissions were also to be reduced, the result may instead be an increase of marine NPF. The ADCHEM model results were furthermore compared to the NanoMap analysis of the same period. The comparison showed that the modelled and the inferred NPF in the marine areas coincided to a large extent. The consistency between the modelled and the inferred NPF is an encouraging result and provides a first verification of the NanoMap analysis.Ville Berg Malmborg Skeppstrafiken ökar antalet nanopartiklar i atmosfären I den här studien där aerosoler, luft-partiklar, studerats i marin miljö visar resultaten att utsläpp från skeppstrafiken kan bidra till att öka antalet nanopartiklar i luften. De partiklar som studerats här är i första hand de allra minsta nanopartiklarna som bildas i atmosfären. Dessa bildas vid ungefär 1 nanometer genom nypartikelbildning (NPB) och om dessa växer kan de potentiellt få stor inverkan på klimatet och molnbildning i atmosfären. Skeppspartiklarna bildas framförallt direkt vid förbränning av fossilt bränsle och kallas primärpartiklar. Gasutsläpp från skeppstrafiken kan leda till att partiklar bildas vid ett senare tillfälle i atmosfären, så kallade sekundärpartiklar. Vid NPB bildas enbart sekundärpartiklar. NPB är en process där ett ämne i gas-fas kondenserar till flytande eller fast fas. NPB kan påverka klimatet när de små partiklarna växer till större storlekar och bildar så kallade kondensationskärnor. Kondensationskärnor är partiklar som tillåter vattenånga att kondensera vid de förhållanden som råder i atmosfären. Dessa partiklar är därför nödvändiga för bildandet av moln. Tidigare studier har visat att NPB kan bidra med 5-50 % av alla kondensationskärnor globalt sett och förändringar i NPB kan därför kraftigt påverka klimatet. För att studera den antropogena påverkan på NPB i marina miljöer tillämpades i studien två metoder. Förhållandena för NPB i den marina atmosfären över Nordsjön simulerades med hjälp av en aerosol-modell. Vidare användes en mätbaserad metod som kallas NanoMap för att påvisa var och hur ofta NPB sker i marina miljöer. Resultaten från NanoMap-studien visar att NPB är ett ganska vanligt fenomen i den marina atmosfären i både Nordsjön, Östersjön och Medelhavet. Ett viktigt resultat visar på en anmärkningsvärt hög sannolikhet för NPB i marina områden med kraftig mänsklig aktivitet. Figur 1 visar resultat från NanoMap-studien i östra Medelhavet samt inringade områden med kraftiga utsläpp från skeppstrafiken, enligt den europeiska samarbetsorganisationen EMEP. I modellstudien där NPB simulerades i Nordsjön framkom att stora antropogena utsläpp av primärpartiklar kan leda till mindre NPB. Dock visade resultaten att den sammanlagda effekten av utsläppen av både gaser och primärpartiklar från skeppstrafiken ger en ökning av NPB över hav och i kustnära miljöer. Den internationella sjöfartsorganisationen har möjlighet att reglera utsläppen från skeppstrafiken. Nya regleringar som träder i kraft den 1 januari 2015 skall minska skeppsutsläppen av svaveldioxid i Nordsjön till en tiondel av dagens värde. Enligt resultaten i denna studie kan detta leda till mindre frekvent NPB i Nordsjön. Eftersom den slutgiltiga ökningen eller minskningen i NPB kan få effekter för klimatet, då antalet kondensationskärnor i luften sannolikt kan påverkas, finns ett starkt behov av fler studier av NPB som klarlägger både antropogena och biogena källor till NPB. Handledare: Adam Kristensson, Pontus Roldin och Erik Swietlicki Examensarbete 60 hp i Fysik, 2014 Fysiska institutionen, Lunds Universite
OCEAN ACIDIFICATION
Ocean acidification is a consequence of the anthropogenic release of carbon dioxide (CO2) to the atmosphere. When CO2 is dissolved in water it affects the composition of ions and lowers the pH of the water. As the partial CO2 pressure in the atmosphere increases a new balance is reached with the surface waters which causes the pH of the surface oceans to decrease. For small shallow seas this effect may be worse than in the oceans because of the limited vertical mixing of deep water and the limited buffering capability (alkalinity). A decrease in ocean pH may have direct effects on ecosystems and indirect effects where the saturation states of calcium carbonates are the most important. This project aims to model projections of future pH of the Baltic Sea surface waters from several CO2 scenarios suggested by the IPCC. A predictive, deterministic model was constructed to project future changes in pH based on the atmospheric CO2 partial pressure, alkalinity and the equilibrium of ions. From the model the ion concentrations can be calculated and used to calculate projections of the saturation state of calcite and aragonite of the Baltic Sea surface waters. Projections of Baltic Sea pH during the 21st century have been made using the model and the CO2 scenarios A1FI, A2 and B2 described by the IPCC. For these scenarios the projections show a decrease in pH by 0.2-0.4 units. If possible changes in alkalinity, which may be a result of changes in river run off to the Baltic Sea, are included the decrease in pH may be as large as 0.5 units. Projections for calcium carbonate indicate that it is possible that calcite becomes under saturated in spring and autumn during the 2050's but is not likely to become under saturated during summers. Aragonite is in our model projected to become under saturated in all seasons already in the 2040's. The magnitude of our projected changes in pH and saturation states of calcite and aragonite has been reported by SMHI to cause negative effects on calcifying organisms and may have effects on the ecosystem as a whole
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