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This paper provides an update of our previous scaling relations between galaxy-integrated molecular gas masses, stellar masses, and star formation rates (SFRs), in the framework of the star formation main sequence (MS), with the main goal of testing for possible systematic effects. For this purpose our new study combines three independent methods of determining molecular gas masses from CO line fluxes, far-infrared dust spectral energy distributions, and similar to 1 mm dust photometry, in a large sample of 1444 star-forming galaxies between z = 0 and 4. The sample covers the stellar mass range log(M-*/M-circle dot) = 9.0-11.8, and SFRs relative to that on the MS, delta MS = SFR/SFR (MS), from 10(-1.3) to 10(2.2). Our most important finding is that all data sets, despite the different techniques and analysis methods used, follow the same scaling trends, once method-to-method zero-point offsets are minimized and uncertainties are properly taken into account. The molecular gas depletion time t(depl), defined as the ratio of molecular gas mass to SFR, scales as (1 + z)(-0.6) x (delta MS)(-0.44) and is only weakly dependent on stellar mass. The ratio of molecular to stellar mass mu(gas) depends on (1+ z)(2.5) x (delta MS)(0.52) x (M-*)(-0.36), which tracks the evolution of the specific SFR. The redshift dependence of mu(gas) requires a curvature term, as may the mass dependences of t(depl) and mu(gas). We find no or only weak correlations of t(depl) and mu(gas) with optical size R or surface density once one removes the above scalings, but we caution that optical sizes may not be appropriate for the high gas and dust columns at high z.

In this second installment of the series, we look at the internal kinematics of the multiple stellar populations of the globular cluster omega Centauri in one of the parallel Hubble Space Telescope (HST) fields, located at about 3.5 hal-flight radii from the center of the cluster. Thanks to the over 15 yr long baseline and the exquisite astrometric precision of the HST cameras, well-measured stars in our proper-motion catalog have errors as low as similar to 10 mu as yr(-1), and the catalog itself extends to near the hydrogen-burning limit of the cluster. We show that second-generation (2G) stars are significantly more radially anisotropic than first-generation (1G) stars. The latter are instead consistent with an isotropic velocity distribution. In addition, 1G stars have excess systemic rotation in the plane of the sky with respect to 2G stars. We show that the six populations below the main-sequence (MS) knee identified in our first paper are associated with the five main population groups recently isolated on the upper MS in the core of cluster. Furthermore, we find both 1G and 2G stars in the field to be far from being in energy equipartition, with eta(1G) = -0.007 +/- 0.026 for the former and eta(2G) = 0.074 +/- 0.029 for the latter, where eta is defined so that the velocity dispersion sigma(mu) scales with stellar mass as sigma(mu) proportional to m(-eta). The kinematical differences reported here can help constrain the formation mechanisms for the multiple stellar populations in omega Centauri and other globular clusters. We make our astro-photometric catalog publicly available.

No description available.

Context: This thesis focused on two main areas of golf performance. Firstly, centre of pressure excursions influence on full golf swing performance, as despite golf coaching literature placing importance on weight transfer, literature into this mechanism is limited. Secondly, the area of the golf putt was examined; few studies have investigated the biomechanics into the putting stroke despite it being identified as the most important performance factor within golf. Areas of investigation were, centre of pressure excursions during the putting stroke, the impact point on golf ball and movement variability on performance outcomes being the ball roll kinematics. Aims: To examine biomechanical factors that influence golf performance. Centre of pressure excursion during the full golf swing and putting stroke were examined. Additionally, body segment kinematics and variability of rotations were correlated with putting performance outcomes. The impact point on the golf ball was considered as a mechanism that can cause variability of the kinematic ball roll. Subjects: All subjects used in this thesis were actively playing golf. Subjects were categorised using the golf handicap system. For studies assessing reliability, validity or isolating putter stroke kinematics a mechanical putting robot was used. Methods: Correlational research whereby no variables were manipulated was predominantly adopted throughout this thesis to establish relationships between biomechanical parameters and golf performance. Biomechanical parameters were assessed using the appropriate data collection and analysis techniques; this included the variability associated with segment rotations. Results: Significant differences were observed for the centre of pressure excursions along the mediolateral axis between three different golf clubs (full swing). For the putting stroke low handicap golfers demonstrated lower centre of pressure excursions along the anteroposterior axis in comparison to high handicap golfers, additionally, a large amount of inter-subject variability was observed for centre of pressure excursions. In regards to the impact point on the golf ball, significant associations were identified between impact variables and the performance measures horizontal launch angle and whether the ball was pushed or pulled, these results were not replicated with human participants. It was identified that the relationship between the centre of mass displacement and centre of pressure excursions is a complex one and that movement variability had a detrimental effect on the horizontal launch angle and therefore performance. Conclusions: The results from the full swing analysis of this thesis suggest that stance width may influence the amount of centre of pressure excursions that occur. For the golf putting stroke, golfers and coaches should reduce the amount of variability associated with the technique to improve performance. Regarding future scientific research, a combination of individual analysis accompanying group-based analysis should be utilised due to the large inter-subject differences observed.

Abstract Over recent years the progress in actuator and microelectronics technology has made intelligent suspension systems feasible. These systems are designed to reduce the drivers' exposure to harmful vibration, as well as to improve the handling properties of the vehicle. Due to widespread use of vehicles as an example of a true MIMO-system, a myriad of different control schemes and algorithms can be found in the literature for these systems. Linearized models are commonly used when the control algorithms are derived. This thesis describes the development of a new analytical full vehicle model, which takes the essential kinematics of the suspension system into account, as well as a new approach to controlling the full vehicle vibration problem. The method of calculating the desired damping forces for each of the semi-active actuators is based on the skyhook theory and this new model is introduced. The performance of the control schemes is evaluated with simulations in a virtual environment. For the excitation to the vehicle, standardized ISO-tracks, washboard tracks and single bump tracks were used. The performance between the two different semi-active control systems and the passive system are compared in terms of damping the vibration, variation of the dynamic tire load and demand for rattlespace. The damping of vibration evaluates both the ability to suppress the vibration on heave, pitch and roll degrees of freedom and ability to reduce the drivers' exposure to harmful whole body vibration. The frequency distribution of the vibration was also reviewed. Variation of dynamic tire contact force is evaluated as an RMS-value and the demand for rattlespace is evaluated as a percentage value of the used rattlespace compared to the maximum free stroke provided by the suspension hardware. As a result from this work, the theory and simulation results are presented. Also a new vehicle model, which takes the essential non-linearity caused by suspension kinematics into account, is presented including all the mathematics needed. The comparison between the passive and the semi-active concepts has been performed on the basis of simulation results. These results show that the novel semi-active concept reduces the driver's exposure to vibration induced by terrain undulations better than any earlier proposed version. Also variation of dynamic tire load is reduced with a novel concept, while it suffers a drawback in the demand for the rattlespace.

This thesis introduces a new type of walking machine that appears promising due to its relative simplicity and efficiency. After an introduction to a selection of previous walking machines, the new machine’s history, advantages, operation and a method for solving its kinematics are given. Early attempts to optimize the mechanism to a range of criteria are described and their shortfalls exposed. A second attempt to optimize the leg geometry by genetic algorithm is detailed and the results of this search discussed. A mechanics model of a hypothetical machine is developed from first principles and the implications of the analysis described. Stability limits and tractive abilities of the machine are explored. A method for determining the loads on the links that constitute the leg and the vehicle chassis is given. A series of prototypes has been constructed and discussions of these machines are given. The most recent prototype is used in a pair of experiments to validate the kinematic and kinetic models. The experimental method, a statistical analysis of results and a discussion are provided for each. The thesis concludes by considering what work remains to be done before a practical cargo carrying transport walking machine can be designed. / Prof. A.L. Nel

Dans l'Univers local, il existe une relation très étroite entre la morphologie d'une galaxie et d'autres paramètres physiques comme, par exemple, leur cinématique intrinsèque. À grand redshift, il n'est pas clair si cette relation est toujours valide. La cinématique des galaxies est un des outils puissants pour l'étude des processus physiques qui gouvernent la formation des galaxies, en traçant les distributions intrinsèques aux galaxies de matière noire et lumineuse, et leur évolution dans le temps. Cette thèse présente le nouveau sondage HR-COSMOS, dont le but fut d'acquérir le premier échantillon statistique et représentatif de cinématique de galaxies à formation d'étoiles dans le champ profond HST/ACS COSMOS dans la plage de redshifts 0<z<1.2. Environ 800 galaxies à raie en émission ont été observées avec le spectrographe multi-fentes ESO-VLT/VIMOS dans son mode haute résolution spectrale (R=2500). J'ai effectué une analyse cinématique du sous échantillon de 82 galaxies de notre intervalle de redshifts les plus élevés 0.75<z<1.2 et j'ai établi la relation d'échelle de Tully-Fisher avec la masse stellaire à z~0.9. En utilisant la même méthodologie et analyse des données, j'ai analysé le sous-échantillon de 186 galaxies dans notre intervalle de redshifts les plus bas 0.01<z<0.375, pour tracer l'évolution de cette relation au sein du même échantillon. J'ai confirmé l'absence d'évolution de la relation de Tully-Fisher avec la masse stellaire depuis 8 milliards d'années. J'ai de plus dérivé les masses dynamiques de ces deux sous-échantillons et j'ai établi l'augmentation du rapport masse stellaire sur masse dynamique et de sa dispersion en fonction de la masse stellaire. / In the local Universe it exists a tight relation between the galaxy morphology and other physical parameters, like the galaxy internal kinematics. At higher redshift it is not clear if this relation still exists. The galaxy kinematics is one of the best tool to study the physical processes that govern the galaxy formation, by tracing the galaxy internal distributions of luminous and dark matter and their evolution with time. This thesis presents the new survey HR-COSMOS aimed to obtain the first statistical and representative sample to study the kinematics of star-forming galaxies in the treasury HST/ACS COSMOS deep field at redshift 0<z<1.2. About 800 emission-line galaxies were observed with the multi-slit spectrograph ESO-VLT/VIMOS in high-resolution spectral mode (R=2500). I performed a kinematic analysis of the sub-sample of 82 galaxies in the highest redshift range, 0.75<z<1.2, and I established the stellar-mass Tully-Fisher scaling relation at z~0.9. Using the same methodology and data analysis, I analyzed the sub-sample of 186 galaxies at the lowest redshift 0.01<z<0.375 to trace any evolution of the relation within the same sample. I confirmed beyond a doubt the non evolution of the stellar mass Tully-Fisher relation since 8 billion year, although a morphological evolution is observed. I have moreover derived the dynamical masses of those two sub-samples and I have established the increasing trend of the stellar-to dynamical mass ratio and its scatter as function of the stellar mass.

We describe how to estimate the velocity dispersions of ultradiffuse galaxies (UDGs) using a previously defined galaxy scaling relationship. The method is accurate for the two UDGs with spectroscopically measured dispersions, as well as for ultracompact galaxies, ultrafaint galaxies, and stellar systems with little or no dark matter. This universality means that the relationship can be applied without further knowledge or prejudice regarding the structure of a galaxy. We then estimate the velocity dispersions of UDGs drawn from two published samples and examine the distribution of total masses. We find, in agreement with the previous studies of two individual UDGs, that these systems are dark matter dominated systems, and that they span a range of at least 10(10) < M-200/M-circle dot < 10(12). These galaxies are not, as an entire class, either all dwarfs or all failed L-* galaxies. Estimates of the velocity dispersions can also help identify interesting subsets of UDGs, such as those that are likely to have the largest mass-to-light ratios, for subsequent spectroscopic study.

We present new proper motion (PM) measurements of the dwarf spheroidal galaxies (dSphs) Draco and Sculptor using multiepoch images obtained with the Hubble Space Telescope ACS/WFC. Our PM results have uncertainties far lower than previous measurements, even those made with the same instrument. The PM results for Draco and Sculptor are (mu(W),mu(N))(Dra) = (-0.0562 +/- 0.0099, -0.1765 +/- 0.0100 mas yr(-1) and (mu(W), mu(N) )(Scl) = (-0.0296 +/- 0.0209, 0.1358 +/- 0.0214 mas yr(-1)) -1. The implied Galactocentric velocity vectors for Draco and Sculptor have radial and tangential components: (V-rad, V-tan)(Dra) =(-88.6, 161.4) +/- (4.4, 5.6) km s(-1) and (V-rad, V-tan )(Scl) = (72.6, 200.2)+/-(1.3, 10.8) km s(-1). We study the detailed orbital histories of both Draco and Sculptor via numerical orbit integrations. Orbital periods of Draco and Sculptor are found to be 1-2 Gyr and 2-5 Gyr, respectively, accounting for uncertainties in the Milky Way (MW) mass. We also study the influence of the Large Magellanic Cloud (LMC) on the orbits of Draco and Sculptor. Overall, the inclusion of the LMC increases the scatter in the orbital results. Based on our calculations, Draco shows a rather wide range of orbital parameters depending on the MW mass and inclusion/exclusion of the LMC, but Sculptor's orbit is very well constrained, with its most recent pericentric approach to the MW being 0.3-0.4 Gyr ago. Our new PMs imply that the orbital trajectories of both Draco and Sculptor are confined within the " Disk of Satellites," better so than implied by earlier PM measurements, and likely rule out the possibility that these two galaxies were accreted together as part of a tightly bound group.