Neutral two- and three-pion productions in proton-proton collisions at a center of mass energy of 2.465 GeV have been studied using the WASA detector and an internal pellet target at the CELSIUS storage ring in Uppsala. An important part of the detector for the measurments was a central electromagnetic calorimeter composed of 1012 CsI crystals, which measured the photons originating from neutral pion decays. Test measurements and calibration procedures for this detector part were carried out. An important part of the analysis was the identification of the neutral pions from the invariant mass of the decay gammas and the use of Monte Carlo simulations to understand the detector responds. Total cross sections for the pp→ppπ0π0 and pp→ppπ0π0π0 reactions are presented as well as distributions of relevant kinematical variables for the pp→ppπ0π0 reaction. The distributions show significant deviations from phase space predictions. These deviations are typical for resonance production. The excitation of two simultaneous Δ resonances seems to be the main reaction mechanism.

Reaction cross sections were measured for protons at 65.5 MeV, for deuterons at 37.8, 65.5, 97.4 MeV, for 3He at 96.4, 137.8, 167.3 MeV, and for 4He at 69.6, 117.2, 163.9 and 192.4 MeV. Targets were 9Be, 12C, 16O, 28Si, 40,48Ca, 58,60Ni, 112,116,118,120,124Sn and 208Pb. 48Ca and 118Sn targets were used only for some of the measurements. Rest of the targets have been measured for all energies and projectiles but 4He at 69.6 MeV where reaction cross sections were measured for 9Be, 12C, 16O, 28Si, 40Ca targets. A modification of a standard attenuation technique was used. Details of the experimental design are presented. Experimental uncertainties were 2-3% for p, 3% for d and 3-10% for 3,4He. A strong forward peaking of the reaction products was observed for 3,4He. Therefore the standard reaction cross section measurement technique was not applicable for these projectiles. The forward peaking is also responsible for the increase of experimental uncertainties for these projectiles. The forward peaking of the reaction products is not known for other projectiles and has also not been observed with 3,4He at different - both higher and lower - energies. Possible explanations for this phenomenon are discussed. Optical model calculations of the reaction cross sections are in good agreement with the measured values. The measurements were performed with beams from the Gustav Werner cyclotron at the The Svedberg Laboratory, Uppsala.

This thesis presents two measurements of the top quark pair production cross section at sqrt{s} = 1.96 TeV using data from the DØ experiment. Both measurements are performed in the dilepton final state and make use of secondary vertex b-tagging. With 158 pb-1 of data in the electron-muon final state, the measured cross section is: σ(top-antitop) = 11.1 +5.8 -4.3 (stat) +- 1.4 (syst) +- 0.7 (lumi) pb. With 425 pb-1 of data in the electron+track and muon+track final states, the measured cross section is: sigma(top-antitop) = 6.3 +2.1 -1.8 (stat) +- 1.1 (syst) +- 0.4 (lumi) pb. Both measurements are in agreement with the prediction from perturbative QCD calculations. In addition, an estimate of the DØ silicon detector lifetime is presented. The radiation damage is determined by studying the depletion voltage of the silicon sensors as a function of time. Based on this data the silicon detector is estimated to remain operational up to delivered luminosities of 6-8 fb-1.

This study was undertaken to investigate the involutional changes of the uterus and uterine cavity by ultrasound (US), gray-scale and Doppler, after normal delivery, and to compare with the corresponding findings from women with puerperal complications, particularly retained placental tissue (RPT). The overall design was exploratory and prospective, with the use of descriptive statistics for analysis. Forty-two women with uncomplicated vaginal term delivery were examined on post-partum days 1, 3, 7, 14, 28 and 56. The AP diameters of the uterus and uterine cavity and morphological findings were recorded. The maximum AP diameters of the uterus and uterine cavity diminished from 92.0 mm on day 1 to 38.9 mm at day 56 and from 15.8 mm at day 1 to 4.0 mm at day 56, respectively. The uterus was most often empty in the early and late puerperium while a mixed echo pattern over the whole cavity was found during mid puerperium (I). Seventy-nine women with secondary post partum hemorrhage (SPH) were examined on the day they presented with clinical symptoms. US revealed an echogenic mass in the uterine cavity in 17 of 18 patients treated surgically and histology confirmed placental tissue in 14 of these. Sixty-one patients with either an empty cavity or mixed echo pattern had an uneventful puerperal course after conservative treatment (II). AP diameters and morphological findings for 55 women with endometritis, 28 after caesarean section and 20 after manual evacuation of the placenta overlapped extensively with normal references (III). The physiological vascular involution studied in 45 women after normal delivery showed that PI and RI indices did not change significantly until day 28 postpartum. The presence of at least one uterine artery notch was found in 13.3% of the women at day 1 and in 90.6% at day 56 postpartum (IV). PI and RI values were measured and compared with reference values in 20 women with clinical suspicion of RPT who were to undergo surgical evacuation. Mean resistance indices were below the 10th percentile for eight of these 20 women, but overlapping was considerable. Doppler US has limited value as a diagnostic tool for RPT. The absence of a hyper-vascular area in the myometrium does not exclude RPT but an echogenic mass in the cavity is a sign of RPT (V).

During the flight of missiles, depending on the flight conditions, rotation of missiles around its centerline can cause instabilities. To override this issue, missile generally is designed in 2 sections. In the missile, the rear tail section and the front section are to rotate freely by means of bearings. Tail section on which bearings are mounted is designed according to thermal loads due to flow of hot gasses through the nozzle and mechanical loads due to inertial load, interference fit and thread preload which appear during flight of missile. The purpose of this thesis is to determine the most suitable structural parameters according to the flight conditions of missile. The geometrical and load parameters which have effect on the results were determined. Finite element model is formed by using FEA software. After that, transient nonlinear thermo-mechanical analyses are performed and the most effective parameter on VM (Von-Mises) stress and force is determined. DOE (Design of Experiments) method was used to determine the most suitable values for the structural parameters. Totally 27 different configurations are studied to achieve to the most suitable values for variable set. It is observed that VM stress and force results for all configurations are within the &plusmn / %5 ranges. So this means parameters don&rsquo / t affect the systems response very much. By taking manufacturing processes into consideration, configuration with the highest bearing inner/outer ring interference is taken. From the comparison of the results, the most suitable configuration is obtained after checking forces and VM stress on the bearings.

QC 20100623

La détermination de la section efficace d'absorption de composés atmosphériques est indispensable pour leurs mesures de concentration. Plus les valeurs de sections efficaces sont exactes, meilleure est la détermination des concentrations atmosphériques. À l'heure actuelle, la valeur de la section efficace d'absorption de l'ozone à 253,65 nm servant de standard pour la mesure de concentration de l'ozone est entachée d'une erreur de 2% et est controversée. Pour cette raison, nous avons développée un photomètre permettant d'obtenir des sections efficaces d'absorption avec une très bonne exactitude à 253,65 nm. Le but était d'atteindre une précision inférieure à 1 %. Le photomètre réalisé a été testé sur le styrène, un composé organique volatil (COV) aromatique. Les COVs comme l'ozone sont des polluants de la troposphère qui absorbent fortement dans l'UV. Outre son intérêt de molécule test, le styrène comme de nombreux COVs, a une section efficace d'absorption dans l'UV connue avec une mauvaise précision. La forte absorbance du styrène nous a obligé à travailler en basse pression (en dessous de 1 Torr). Dans ce domaine de pression, il apparaît une non-linéarité dans la mesure de pression que nous avons corrigée en mesurant la transpiration thermique du styrène. Nous avons donc obtenu la première mesure de transpiration thermique d'une molécule aromatique. Grâce à une estimation précise des erreurs et des corrections faites, nous avons montré que le photomètre réalisé atteignait bien une précision inférieure au %. Nous avons obtenu une section efficace absolue d'absorption du styrène de 1,521E−17 cm^2 avec une incertitude de 0,6 % pour un intervalle de confiance de 95 %.

The reaction cross section gives the probability that a particle will undergo a nonelastic process when passing through a nuclear medium. Therefore reaction cross section data are of importance both for theoretical studies and for applications in such diverse fields as medicine, biology, astrophysics and accelerator-driven transmutation of nuclear waste. There exist many data sets with angular distributions of elastic scattering, but very few measurements of the complementary reaction cross section have been performed. The measurement is in principle simple but has in practice proved to be very difficult to perform, and the relatively limited amount of experimental data displays some serious inconsistencies. Results from measurements of reaction cross sections are presented for: • 3He on 9Be, 12C, 16O, 28Si, 40Ca, 58,60Ni, 112,116,118,120,124Sn and 208Pb at 96, 138 and 167 MeV • protons on 12C, 40Ca, 90Zr and 208Pb at six energies in the energy range 80-180 MeV, and on 58Ni at 81 MeV. Experimental uncertainties were 3-9% for 3He and 1.5-8% for protons. The apparatus and the experimental method used for the measurements of reaction cross sections, using a modified attenuation technique, is described. The detection method enables simultaneous measurements of reaction cross sections for five different sizes of the solid angles in steps from 99.0 to 99.8% of the total solid angle. The final results are obtained by extrapolation to the full solid angle. Experimental results are compared with predictions from optical model calculations using phenomenological global optical potentials. Phenomenological parametrizations of reaction cross sections for scattering of projectiles on targets are presented. The parametrizations show that reaction cross sections are very sensitive to matter distributions at very large radii of both the projectile and the target. For protons the derived relations makes it possible to predict the reaction cross sections on targets for which no experimental data exist.

This thesis presents an Advanced Placement curriculum for the concentration section of the Drawing Portfolio. It is intended as a teaching tool to encourage and develop creative strategies related to idea generation and refinement based on creative problem solving, which is essential to the development of an effective concentration. One of the most difficult problems faced by Advanced Placement Studio Art students is idea generation for the artwork related to a central topic for the concentration section of their portfolios. This curriculum introduces lessons based on artist research, brainstorming, synectics, and SCAMPER techniques designed to foster creative idea generation for artwork development. It also gives students a tool with which to analyze the ideas generated based on specific criteria necessary to the concentration. This curriculum specifically encourages the creative process in students and provides teachers with a foundation with which to begin a unique and highly personal journey by the individual student.

Rotary draw bending, which has very good flexibility and easy tooling, is one of the most preferred bending types for tubular profiles. Cross-section distortion and the spring-back phenomena are commonly faced problems in bending processes. Spring-back is the inevitable problem that is to be solved by manufacturer, generally by overbending. For hollow tubes cross-section distortion is another difficulty since using hollow tubes results in higher strain rates and distortions. During the process the thickness of the hollow tube at the inner surface, which is contacting with the die, increases and the thickness of the tube at the outer surface decreases. Wrinkling is another important defect that occurs at the inner surface of the tube in large diameter thin walled tube bendings. This research compares the experimental results with the finite element analysis of the rotary draw bending process. The aim is to obtain bending characteristics of the two material types, SS304 and St37 and so, to reduce the number of the bending in manufacturing. The main parameters in rotary draw bending process are the bending angle, bend radius, material properties and the geometry of the tube that is to be bent. In this study, to deal with the process, two different materials, three different bending angles and three different tube geometries are used in experiments as well as in finite element analysis. In finite element analysis explicit method is used. It is seen that the experimental results are in good agreement with the numerical results.