Magister Scientiae (Nutrition Management) - MSc(NM) / Despite evidence-based proof on the benefits of breastfeeding, little progress has been made globally to improve breastfeeding rates (The Lancet, 2016), including in South Africa. Despite many attempts to improve breastfeeding rates worldwide, women are still choosing to stop breastfeeding or avoid it due to various factors (The Lancet, 2016). Aim: To explore the factors influencing the exclusive breastfeeding rate within the first 14 weeks postpartum with mothers in the Khayelitsha Eastern Substructure.

In der Dissertation ist eine Methodik beschrieben, die es ermöglicht, mittel- und langwellige Gradientenänderungen auf Grundlage der Rohdaten des bei der DB AG zur Gleisgeometrieprüfung gemäß RIL 821.2001 eingesetzten Messfahrzeuges RAILab zu detektieren. Weil mittel- und langwellige Längshöhenfehler eines Gleises die Verschlechterung der Tragfähigkeitseigenschaften von Bettung/Unterbau/Untergrund anzeigen, können mit der Methodik Zustandsänderungen von Erdkörpern kontrolliert werden. Dabei ist eine geodätische Aufnahme von Verformungen, wie sie derzeit beim Monitoring von Erdkörpern im Allgemeinen angewendet wird, nicht erforderlich. Die Methodik wurde an einem Streckenabschnitt, in welchem infolge von verformungsempfindlichen Böden im Untergrund erhebliche Gleisverformungen eingetreten waren, erprobt und durch Vergleich mit geodätischen Messdaten verifiziert. Weiterhin wurde ein Vorschlag zur Festlegung von Aufmerksamkeitswerten für mittel- und langwellige Höhenänderungen unterbreitet. Die vorgeschlagenen Aufmerksamkeitswerte wurden wirkungsbezogen auf Grundlage der Vertikalbeschleunigung abgeleitet, die ein Feder-Dämpfer-Modell bei der Überfahrt über einen aus den RAILab-Gleismessdaten rekonstruierten Höhenverlauf eines Gleises erfährt. Über zwei Beispiele der Anwendung der Methodik bei der Sonderinspektion von Erdkörpern wird berichtet.

Vibration Assisted Machining (VAM) refers to a non-conventional machining process where high-frequency micro-scale vibrations are deliberately superimposed on the motion of the cutting tool during the machining process. The periodic separation of the tool and workpiece material, as a result of the added vibrations, leads to numerous advantages such as reduced machining forces, reduction of damages to the material, extended tool life, and enabling the machining of brittle materials. Vibration Assisted Drilling (VAD) is the application of VAM in drilling processes. The added vibrations in the VAD process are usually generated by incorporating piezoelectric transducers in the structure of the toolholder. In order to increase the benefits of the added vibrations on the machining quality, the structural dynamics of the VAD toolholder and its coupling with the dynamics of the piezoelectric transducer must be optimized to maximize the portion of the electrical energy that is converted to mechanical vibrations at the cutting edge of the drilling tool. The overall dynamic performance of the VAD system depends of the dynamics of its individual components including the drill bit, concentrator, piezoelectric transducer, and back mass. In this thesis, a substructure coupling analysis platform is developed to study the structural dynamics of the VAD system when adjustments are made to its individual components. In addition, the stiffness and damping in the joints between the components of the VAD toolholder are modelled and their parameters are identified experimentally. The developed substructure coupling analysis method is used for structural modification of the VAD system after it is manufactured. The proposed structural modification approach can be used to fine-tune the dynamics of the VAD system to maximize its dynamic performance under various operational conditions. The accuracy of the presented substructure coupling method in modeling the dynamics of the VAD system and the effectiveness of the proposed structural modification method are verified using numerical and experimental case studies. / Graduate

Bridge design and construction practice in former USSR, especially Russia, is not much known to the foreign engineers. Many advanced structural theories and construction practices have been established. In 1931, Franklin D. Roosevelt said, “There can be little doubt that in many ways the story of bridge building is the story of civilization. By it, we can readily measure a progress in each particular country.” The development of bridge engineering is based on previous experiences and historical aspects. Certainly, the Russian experience in bridge engineering has its own specifics. Bridge design proceeds in accordance with local standards and specifications. This study considers the basic rules and standards in bridge design in the North of Russia, the work includes the overview of Russian design concepts. The paper shows the design of typical concrete bridges including all calculations and analyses for future bridge stability and also drawings for visualisation. The results of the work are conclusions based on performing the required design calculations, drawings, preparing a final estimate and preparations for the construction. There are also some notes concerning the Russian design systems, computer programs for designing and computing and, finally, comparison of the Russians design standards and the Eurocode.

Vibration assisted drilling (VAD) is a type of machining process in which high-frequency vibrations with a small amplitude are induced in the cutting tool to improve the cutting process of hard and brittle materials. These vibrations create an unsteady repetitive processing effect which eventually reduce the cutting forces. It is also crucial to measure these forces in some way because their knowledge directly aids in determining the best machining parameters. Direct and indirect methods can be used to measure these forces, but due to serious limitations of direct measurement methods, an indirect measurement method is required which is capable of online monitoring of high-frequency cutting forces. In this thesis, an indirect method is proposed to estimate thrust force and torque from the voltage signal generated by piezoelectric sensor and torsional deflection signal measured through piezoelectric accelerometer. The estimation of two input signals requires a multi-input multi-output (MIMO) model of VAD system which is developed using Receptance Coupling and Substructure Analysis (RCSA) method. Experimental and numerical methods are used to validate the constituent single-input single-output (SISO) transfer functions of the MIMO model. As the estimated forces are distorted by the dynamics of VAD structure, a Kalman Filter is employed to compensate the dynamics. The accuracy and similarity of results is determined by comparing the estimated cutting force values with the force measured from a load cell in time and frequency domain. The reported experimental results confirm the possibility of using Kalman Filter in estimating high-frequency forces generated in VAD process. / Graduate

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京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第21081号 / 工博第4445号 / 新制||工||1691(附属図書館) / 京都大学大学院工学研究科社会基盤工学専攻 / (主査)教授 杉浦 邦征, 教授 KIM Chul-Woo, 教授 清野 純史 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

The focus of this study is on potential problems resulting from construction on expansive soils in Kibaha region, Tanzania. For the fact that most of the affected structures are founded on expansive soils, a clear understanding of the soil behaviour and their interaction with structures, specifically as they relate to shallow foundations, has been of more interest to the study in order to evaluate properly the source of the problem. The geotechnical behaviour of expansive clay soils is investigated by looking into the geomorphologic, geological and climatic conditions and mineralogical composition of the soils in the study area. The geotechnical results are linked with the performance of the foundation as well as structures. Two sites, representative of known problem-areas in Kibaha were selected for geotechnical tests. Geotechnical site investigation consisted of open trial pits, profile description and the collection of both disturbed and undisturbed samples. The collected samples were submitted to soil laboratories at KTH and DIT for mineralogical composition tests, natural water content, density, Atterberg limits and swell tests (free swell and swelling pressure). The results of this investigation indicate that soil in Kibaha contains clay (31%), have high liquid limit (59%) and plastic limit (37%) which indicate high potential swell. Since swell potential and swell pressure are key properties of expansive soils, the swell parameters were measured by free swell tests and one-dimensional oedometer swell tests respectively. The free swell ranged from 100% to 150% and the swell pressure was in the region of 45 kPa. The properties of expansive soils were confirmed by the x-ray diffraction test which showed the presence of montmorillonite in the soil. It is from this fact that the source of the problem is in the expansive soils coupled with poor building materials. Physical conditions of the surveyed properties in the area confirmed the hypothesis of building damages due to poor building materials triggered by expansive soils. In support of the obtained data, the actual behaviour of the foundations is supplemented with prototypes of strip foundations whose performances are to be monitored over a long period. Finally, suggested are the ways forward to solve the problem of foundation on expansive soil. / QC 20101118

The objective of this research is to simulate the response of an isolated substructure such that the response of the substructure in isolation would be the same as the substructure within the structure. Generally, the behaviour of an isolated subsystem (substructure) subjected to dynamic loading is different than the behaviour of the same substructure within a system (structure). This is primarily caused by the boundary conditions that are imposed on the substructure from the surrounding subsystem in the entire structure. A new systematic approach (methodology) is developed for performing impact analysis on the isolated substructure. The developed technique is fundamentally based on enforcing the mode shapes around the boundary of the substructure in the full structure to be similar to the mode shapes of the isolated substructure. This is achieved by providing a consistent adjustment to the loading conditions (impact velocity and mass) to account for the loss of restraint at the interface with the full structure. Another important aspect of this research is experimental validation of proposed method. This method allows the experimental testing of an isolated substructure since the testing is performed by impacting the isolated substructure with an appropriate mass and velocity. In the finite element analysis, the structure is analyzed, and then the isolated substructure simulation is performed using the developed technique. The results obtained from the numerical simulations, for both the substructure in situ and the substructure in isolation, are compared and found to be in good agreement. For instance, the effective plastic strains, kinetic and internal energies for the substructure within the structure and the substructure in isolation range from 7% to 12% discrepancies between two analyses. The numerical simulations of a full structure are verified by performing a series of experimental impact tests on the full structure. Finally, the experimental applicability of the technique is studied and its results are validated with FE simulation of substructure in isolation. This problem of experimentally testing an isolated substructure had previously not been addressed. The comparisons of FE simulation and experimental testing are made based on the deformed geometries, out-of-plane deflections and accelerometer readings. For example, the out-of-plane deformations from the FE analysis and the experimental test were determined to be within 7% to 9%. The experimental validation and numerical simulations indicates the technique is reliable, repeatable and can predict dynamic response of the substructures when tested in isolation. / Thesis / Doctor of Philosophy (PhD)

No description available.