Results of Microgravity Fluid Dynamics Captured with the Spheres-Slosh Experiment

This paper provides an overview of the SPHERES-Slosh Experiment (SSE) aboard the International Space Station (ISS) and presents on-orbit results with data analysis. In order to predict the location of the liquid propellant during all times of a spacecraft mission, engineers and mission analysts utilize Computational Fluid Dynamics (CFD). These state-of-the-art computer programs numerically solve the fluid flow equations to predict the location of the fluid at any point in time during different spacecraft maneuvers. The models and equations used by these programs have been extensively validated on the ground, but long duration data has never been acquired in a microgravity environment. The SSE aboard the ISS is designed to acquire this type of data, used by engineers on earth to validate and improve the CFD prediction models, improving the design of the next generation of space vehicles as well as the safety of current missions. The experiment makes use of two Synchronized Position Hold, Engage, Reorient Experimental Satellites (SPHERES) connected by a frame. In the center of the frame there is a plastic, pill shaped tank that is partially filled with green-colored water. A pair of high resolution cameras records the movement of the liquid inside the tank as the experiment maneuvers within the Japanese Experimental Module test volume. Inertial measurement units record the accelerations and rotations of the tank, making the combination of stereo imaging and inertial data the inputs for CFD model validation

University academic writing for international students: A usage-based approach

This resource is designed specifically to meet the academic writing needs of international students studying at universities in the United States. The materials in the book can be covered within a 14-week semester, but each chapter or section may also be used independently.Based on a series of needs analysis projects, this resource provides an overview of major rhetorical patterns of writing that are commonly used in university settings in the United States. These commonly required genres include descriptive and evaluative summaries, short essays, comparison and contrast assignments, literature reviews, descriptive reports, and proposals. The resource includes chapters that address the structure and purpose of these more common genres, including an awareness of the ways that the target audience and situation should shape the writing of each

Acquisition of Long-Duration, Low-Gravity Slosh Data Utilizing Existing ISS Equipment (SPHERES) for Calibration of CFD Models of Coupled Fluid-Vehicle Behavior

Accurate prediction of coupled fluid slosh and launch vehicle or spacecraft dynamics (e.g., nutation/precessional movement about various axes, attitude changes, ect.) requires Computational Fluid Dynamics (CFD) models calibrated with low-gravity, long duration slosh data. Recently completed investigations of reduced gravity slosh behavior have demonstrated the limitations of utilizing parabolic flights on specialized aircraft with respect to the specific objectives of the experiments. Although valuable data was collected, the benefits of longer duration low-gravity environments were clearly established. The proposed research provides the first data set from long duration tests in zero gravity that can be directly used to benchmark CFD models, including the interaction between the sloshing fluid and the tank/vehicle dynamics. To explore the coupling of liquid slosh with the motion of an unconstrained tank in microgravity, NASA's Kennedy Space Center, Launch Services Program has teamed up with the Florida Institute of Technology (FIT), Massachusetts Institute of Technology (MIT) and the Office of the Chief Technologist (OCT) to perform a series of slosh dynamics experiments on the International Space Station using the SPHERES platform. The Synchronized Position Hold Engage Reorient Experimental Satellites (SPHERES) testbed provides a unique, free-floating instrumented platform on ISS that can be utilized in a manner that would solve many of the limitations of the current knowledge related to propellant slosh dynamics on launch vehicle and spacecraft fuel tanks. The six degree of freedom (6-DOF) motion of the SPHERES free-flyer is controlled by an array of cold-flow C02 thrusters, supplied from a built-in liquid C02 tank. These SPHERES can independently navigate and re-orient themselves within the ISS. The intent of this project is to design an externally mounted tank to be driven inside the ISS by a set of two SPHERES devices (Figure 1 ). The tank geometry simulates a launch vehicle upper stage propellant tank and the maneuvers replicate those of real vehicles. The design includes inertial sensors, data acquisition, image capture and data storage interfaces to the SPHERES VERTIGO computer system on board the flight article assembly. The design also includes mechanical and electronic interfaces to the existing SPHERES hardware, which include self-contained packages that can operate in conjunction with the existing SPHERES electronics

Search for Dark Matter in association with a top quark and a WW-boson in s\sqrt{s} = 13 TeV pp collisions at the ATLAS detector

The Standard Model (SM) is the only model in particle physics containing all observed elementary particles and their interactions. Over the years, its predictions were tested and observed in a number of experiments. However, there are still observations that can not be explained by the SM with one of the most prominent ones being the existence of Dark Matter (DM). While the existence of DM was first theorised through astronomical observations, extensions of the SM allow for a search of DM at the Large Hadron Collider (LHC) as well. Since DM can not be detected directly, final states analysing its existence at the LHC are always designed around high missing transverse energy. This thesis presents a search for DM with data collected by the ATLAS detector in the years 2015-2018 corresponding to an integrated luminosity of 139~$\mathrm{fb}^{-1}$ at a center of mass energy of 13 TeV. The analysis is based on an extended two Higgs doublet model (2HDM+a) where a pseudo-scalar mediator allows the production of DM in the final state. In addition to the DM, a top quark and a $W$-boson-boson are produced in the final state. This thesis mainly focuses on a final state with zero leptons which results in both the $W$-boson-boson and the top quark being required to decay hadronically. In addition to that, the $W$-boson-boson can be expected to have a high momentum in the signal process. Therefore, a dedicated identification algorithm using large-radius jets is employed to select events with at least one hadronically decaying $W$-boson-boson. This allows for a strong distinction against SM background events. In this analysis, several different signal processes are considered, since different parameters can affect the cross section and the distributions of the signal processes. These parameters include different values for the mass of the mediator $a$, the mass of the heavy Higgs boson $H$ and $\tan\beta$. Since no significant excess was found in the signal regions when comparing SM prediction to data, upper exclusion limits on the cross section of the signal processes were calculated with a 95% confidence level (CL). These limits are presented in three different model parameter planes. One such plane presents the upper limits for different values of the mass of the mediator, $m_a$, and the mass of the heavy Higgs boson, $m_H$, while keeping $\tan\beta = 1$. The second and third plane present the upper limits for different values of the mass of the heavy Higgs boson, $m_H$, and $\tan\beta$ while the mass of the mediator $a$ stays constant at $m_a=$ 250~GeV and $m_a=$ 150~GeV. In addition to the upper limits for signal processes with one top quark in the final state, this thesis also provides an upper exclusion limit where this signal process is combined with a process that includes two top quarks in the final state

Hua Guofeng im Bild

Hua Guofeng ist als von Mao Zedong selbst auserwählter Nachfolger in die Geschichte der Kommunistischen Partei Chinas eingegangen. Westliche wie chinesische Forschung haben sich mit dieser, für China wichtigen Übergangszeit bereits ausführlich beschäftigt, wodurch ein neuer Forschungsanstoß mit dieser Arbeit gegeben werden soll. So haben die Kulturwissenschaften in den letzten Jahrzehnten bereits einige Wendungen, sogenannte turns durchlebt, welche Paradigmenwechsel und neue Denkweisen in die Forschung miteinfließen lassen. Basis für die Beschäftigung mit Hua Guofeng ist also eine neue und ist vom sogenannten iconic turn inspiriert. Dieser versucht die enorme Bilderflut, welche wir im vergangenen Jahrhundert erlebt haben und die zunehmende Präsenz von Bildern als Medium zu verwenden, um die Forschung neu zu inspirieren. Es soll also die Welt durch Bilder erkannt werden als lediglich das Bild selbst. Die Bildkultur Chinas der letzten Jahrzehnte war stark von den bunten und beliebten Propagandaplakaten geprägt, wodurch diese Forschungsobjekte dieser Arbeit sind. Die Plakate mit Mao Zedong als großen Vorsitzenden der Partei sind dabei auch im Westen sehr bekannt. Hua Guofeng dagegen wird zwischen den beiden Größen Mao Zedong und Deng Xiaoping im Westen eher vernachlässigt. Deshalb soll diese wichtige Übergangszeit durch die Propagandaplakate Hua Guofengs neu bewertet werden und mit Hilfe des Bildes ein neuer Aspekt in die Erforschung der Zeit zwischen 1976 und 1980 gebracht werden. Die Plakate werden mit einer Kombination aus Roswitha Breckners Segmentanalyse und Erwin Panofskys 3-Ebenen-Modell der Bildinterpretation aufgeschlüsselt. Zunächst wird das tatsächliche Bild in der vor-ikonographischen Analyse in seine einzelnen Komponenten aufgeteilt, diese beschrieben und auch die Kompositionsmerkmale herausgearbeitet. Im zweiten Schritt, der ikonographischen Interpretation werden diese einzelnen Bildsegmente mit dem Hintergrundwissen aus der Sekundärliteratur verknüpft und die dargestellte Szenerie erklärt. Der letzte Schritt der Analyse, die ikonologische Interpretation stellt nun das jeweils behandelte Plakat in den Kontext der anderen Plakate, der Geschichte und der 92 Forschung. Die Geschichte wird hier mit chinesischen Zeitungsartikeln der Zeit der Veröffentlichung des behandelten Plakates erarbeitet. Durch den Vergleich mit der bestehenden Forschung zu diesem Thema wird die Kontinuität in der Darstellung Hua Guofengs herausgearbeitet. Der Forschungszugang über Bilder zur Sinologie bedeutet die Verknüpfung verschiedener Sichtweisen und soll einen neuen Anstoß für die Beschäftigung mit dem Medium der chinesischen Propagandaplakate geben

Measuring luminosity with track counting in the ATLAS experiment

The precise measurement of the luminosity is one of the key requirements for every ATLAS analysis at the Large Hadron Collider (LHC) at CERN. Particularly in high precision experiments, the uncertainty on the luminosity can be one of the main limitations. Therefore, its reduction is the prime goal of the ATLAS luminosity program, requiring a precise understanding of the contributing factors. The two largest individual components are the calibration transfer and the long term stability, both being determined involving the track counting luminosity measurement

Determination of non-perturbative corrections in Z+jets production at the LHC using iterative methods

The aim of the presented thesis was to determine non-perturbative corrections in Z+jets production at the LHC using iterative unfolding. By using the event generator SHERPA, Z+jets events were simulated on hadron and parton level, which were analysed with the program Rivet afterwards. A lot of observables with different sensitivity for non-perturbative effects were examined. Eventually by using RooUnfold a response matrix object could b e created, which contained information about the non-perturbative corrections. Finally another parton level distribution was unfolded with two different metho ds by using the response matrix object. The results of the unfolding was then used to compare these methods. The first method was the bin-by-bin method and the second one was the iterative unfolding

Measuring luminosity with track counting in the ATLAS experiment

The precise measurement of the luminosity is one of the key requirements for every ATLAS analysis at the Large Hadron Collider (LHC) at CERN. Particularly in high precision measurements, the uncertainty on the luminosity can be one of the main limitations. Therefore, its reduction is the prime goal of the ATLAS luminosity program, requiring a precise understanding of the contributing factors. The two largest individual components are the calibration transfer (extrapolating the measurement from the calibrated regime to the physics regime) and the long term stability (stability of the measurement typically over a whole year), both being determined involving the track counting luminosity measurement