No

No / The main objective of this research is to develop an accurate and efficient nonlinear finite element model to study the behaviour headed shear connectors in composite beams with pairs of shear connectors. A numerical model for push test will be prepared to predict capacity, load-slip behaviour and failure modes of headed shear stud. The model will be verified against test results and after validation; it will be used to study the effect of various parameters on the performance of the shear connector.

No

Solvent effects on the chemical exchange of a push pull Ethylenes <p> Chemical exchange rates provide a sensitive probe of solvent effects in solution. The push-pull ethylene methyl 3-dimethylamino-2-cyanocrotonate (MDACC) has three exchange processes E-Z (the same as E' -Z'), E-E', and Z-Z', and we have measured these rates in acetone-d6, chloroform-d, tetrahydrofuran-d8, toluene-d8, methanol-d4, acetonitrile-d3, and methylene chloride-d2 through 1D 1 H.NMR at different temperatures. From this we obtain ΔG+, ΔHt+, ΔS+ of activation for each solvent by employing an Eyring plot. As the solvent changes, ΔH+ is approximately constant whereas ΔS+ follows the solvent polarity. </p> <p> Since the equilibrium constant is less than one, we would expect it to increase with temperature, but it decreases. This is seen in the Van't Hoff plot where the slope is positive indicating that the process of going from the major site to the minor site is exothermic, so not only is the rate governed by entropy effects, but also the equilibrium constant between E and Z. </p> <p> The rotation between the C-N and the C=C bond occurs through a non-concerted mechanism. Two reasons why this occurred was apparent through EXSY, since the intensity of the off diagonal peak varies with different mixing time and second, the rates from C=C rotation (E-Z) and C-N rotations (E-E' and Z-Z') are different at the same temperature </p> / Thesis / Master of Science (MSc)

Denna uppsats ska studera hur befolkningsutveckling och flyttmönster påverkas av lärosäten i Sverige. Sedan 1990-talet har andelen utbildade med högre utbildning sett en ständig ökning. Lärosäten fick med högskolereformen 1993 större frihet hur utvecklingen skulle ske. Samtidigt förändrades utbildningens strukturer från att vara linjebaserad till att vara programbaserad. Detta ledde till att högre utbildning blev mer tillgängliga för individer vilket har lett till ökningen av utbildade i Sverige. Kommuner med lärosäten blir därför mer eftersökta till följd av en högre vilja av att utbilda sig vidare efter gymnasiet.  Denna studie ska därför försöka besvara hur olika kommuner blir påverkade av de lärosäten som finns runt om i landet. Målet för studien är Sveriges 290 kommuner och de lärosäten som är belägna i olika kommuner som erbjuder en högre utbildning, 3 år eller längre eftergymnasial utbildning. Genom användandet av registerdata från Statistiska centralbyrån [SCB] baserat på befolkningen i Sveriges kommuner, ska studien belysa hur olika faktorer kan påverka hur flyttmönster kan synliggöras och förklaras. Trender ska synliggöras utifrån olika utgångspunkter som hur en kommuns socioekonomiska bakgrund påverkar flyttmönster. Även hur push-pull påverkar hur kommuner kan vara attraktiva för vissa och avvisande för andra, där ålder är en faktor i hur en livsstil förändras under tid. Denna studie ska undersöka hur befolkningsutvecklingen sett ut, genom att skapa cirklar med intervallspann på 50 kilometers avstånd från samtliga svenska lärosäten. De kommuner som faller inom detta upptagningsområde kommer att benämnas vara inom ett högre lärosätets influensfält då det även innefattar påverkan utåt genom en export och skapande av kunskap. Därav blir frågan om lärosätenas lokalisering har en påverkan på befolkningsutvecklingen genom sin dragkraft av människor, samt hur stark och hur långt sträcker sig deras influensfält? Studien synliggör mönster hur individer i åldersgruppen 18-25 i större grad flyttar från kommuner utan lärosäten och samtidigt ökar inflyttningen till kommuner med lärosäten. Den största minskningen visar sig vara i kommungrupper inom pendlingsavstånd till kommunerna med lärosäten. Kommuner kring storstäderna och kommuner med högre lärosäten upplever en tillväxt av deras utbildade befolkning och samtidigt en hög nettoutflytt av den yngre åldersgruppen. Samtidigt som en minskning sker bland pendlingskommuner och landsbygdskommuner ser de även en positiv nettoinflytt av äldre åldersgrupperna 46-55 och 56-65. Efter en viss ålder synliggörs ett förändrat flyttmönster med en högre flyttfrekvens från storstäderna och större städer mot pendlingskommuner, mindre stad/tätorter och landsbygdskommuner. Lärosätena har även påverkat kommuner utan lärosäten då generellt alla kommuner ser en positiv ökning i utbildningsgraden, även om den är liten eller i mindre utbredning jämfört med större kommuner. Denna slutsats tolkas bero på att många unga flyttar för högre studier men väljer sedan att flytta därifrån efter avklarade studier vilket ökat den nationella utbildningsgraden.

Cyclic ketene-N,N-acetal chemistry was explored. 2-Methylimidazoline and 2-methyl-1,4,5,6-tetrahydropyrimidine derivatives were prepared from the condensation reactions of diamines with nitriles under Lewis acid catalysis and used as the precursors of cyclic ketene-N,N-acetals including the N-methyl and N-acyl cyclic ketene-N,N-acetals. The reactions of 2-methylimidazoline with excess benzoyl chlorides in THF or MeCN in the presence of triethylamine generate N,N'-diacyl-beta-keto-cyclic ketene-N,N-acetals. The corresponding reactions of 1,2-dimethylimidazoline under the same conditions form the ring-opened (Z)-3-((2-benzamidoethyl)(methyl)amino)-3-oxo-1-phenylprop-1-enyl benzoates. The latter reactions feature the formation of carbon-carbon bonds, carbon-nitrogen bonds, and carbon-oxygen bonds in one operation. The reactions of 2-methyl-1,4,5,6-tetrahydropyrimidine with excess acid chlorides in Et3N/THF generate N,N-diacyl-cyclic ketene-N,N-acetals, with no further acylation on the exocyclic beta-carbons. In contrast, the reactions of 1,2-dimethyl-1,4,5,6-tetrahydropyrimidine under the same conditions form N-acyl-N'-methyl-beta,beta-diketo-cyclic ketene-N,N-acetals, with the dual acylations on the exocyclic beta-carbons. Significant double bond torsion and elongation were observed by the X-ray analysis of an example compound from the latter reactions. The reactions of 2-methylimidazoline and 2-methyl-1,4,5,6-tetrahydropyrimidine with 1,3-diacid chlorides, in the presence of Et3N in refluxing MeCN give highly functionalized potentially bioactive 1,8-naphthyridinetetraones. 2-Methylimidazoline and 2-methyl-1,4,5,6-tetra-hydropyrimidine can be viewed as tridentate nucleophiles which give four consecutive tandem nucleophilic attacks on electrophiles. The reactions of 1,2-dimethylimidazoline and 1,2-dimethyl-1,4,5,6-tetrahydropyrimidine with isocyanates in refluxing MeCN gave bicyclic pyrimidinediones. The reactions of N,N'-dimethyl cyclic ketene-N,N-acetals with various isocyanates generated push-pull alkenes which have never been reported. Significant elongations and torsions of the polarized carbon-carbon double bonds in the novel push-pull alkenes were observed using the X-ray crystallography. The stronger pushing effect of the six-membered cyclic ketene acetal portion in a push-pull alkene, versus the five-membered analog, was detected by reactivity differences for the first time.

No description available.

This article reviews the design and behaviour of composite beams with precast hollow core slabs in multi-storey buildings for gravity loading. A brief history of composite construction and introduction to precast¿composite construction is given, followed by an overview of recent research work on various factors affecting the design. This includes the push-off test procedure, the load¿slip characteristic of the headed shear studs and the design procedures for this type of construction. Finite element modelling of the headed stud shear connectors and the composite beams with precast hollow core slabs are presented. Finally, recommendations and future research work is also suggested.

The behavior and strength of welded shear studs are subjects of ongoing study. In recent years, research has shown that the American Institute of Steel Construction (AISC) specification equations for shear stud strength are unconservative for studs placed in deck with ribs transverse to the steel beam. Twenty-four solid slab push-out tests, 93 composite slab push-out tests, and bare stud tests were performed to study the effects on stud strength of friction, normal load, position of studs in the ribs of steel deck, concrete strength, and stud properties. Stud diameters ranged from 3/8 in. to 7/8 in., deck heights ranged from 2 in. to 6 in., and both single and pairs of studs were tested. The push-out test results from this study were combined with other studies to propose a new stud strength prediction model. Three new beam tests were performed to study the effect of the stud position in the ribs of the steel deck. The results of these tests, along with 61 other beam tests, were used to verify the new stud strength prediction model. A reliability study was performed to determine resistance factors for stud strength and beam strength. / Ph. D.

Ten strategically placed push-pull wells were installed to determine in-situ degradation rates at a creosote contaminated site and to assess the contribution of hybrid poplar trees to polynuclear aromatic hydrocarbon (PAH) remediation. Well positioning enabled comparison between contaminated and non-contaminated locations, as well as comparisons between locations with and without trees. Comparison of areas with and without trees enabled an improved understanding of the role that the phytoremediation system has on the overall degradation of PAHs at the site. Bromide, a conservative, non-reactive tracer, was injected in solution along with dissolved oxygen. Twelve push-pull tests (PPTs) were performed, of which three did not include naphthalene in the injection solution, so that the developed method could be evaluated, tested, and yield an initial set of rates to make seasonal and spatial varying in-situ comparisons. Method comparison used for rate analysis found the highest confidence in the method of Snodgrass and Kitanidis (1998) for zero order rates and the method of Haggerty et al. (1998) for first order rates. The largest zero and first order rates, 2.43 mgnaphthalene/L-hr and 1.25 1/hr, respectively, occurred at treed regions in June. Zero and first order winter rates at treed regions were greater by a factor of at least 2.5 when compared to non-treed regions. Degradation rates at treed regions were found to steadily increase by over four times from winter to summer. Results validate that decay variations attributed to phytoremediation can be detected with the push-pull method. PPTs performed at the Oneida site verified observed trends determined from six years of monitoring data, microbial characterization, and microcosm studies. / Master of Science