Csaba CSEH Engine Connecting Rod Analysis Including Bolts Influence DW, ITE, 2008, 75 pp, 88 fig. The aim of my diploma work is a stress analysis in the material of a connecting rod during a stationary engine regime. Dynamic forces from the connecting rod‘s motion and the forces acting on the bolts are included in the calculations. The whole stress analysis is based on a FEM designed application on a model, that was created in a CAD system package according to the real component.

The project deals with the construction of a multifunctional residential building with 5 apartments, shop offices and law. The building is located in the village of Želechovice Dřevnicí on flat terrain. The house is designed in a structural system Porotherm, covered gable roof 45 °. The building is designed in accordance with the master plan of the municipality of Želechovice Dřevnicí, its character builds on the surrounding buildings and at work are respected by all laws and regulations relating to the design of buildings. The drawing part was processed by computer in AutoCad. Part of the project documentation is part of the drawing, text and calculation. The project is assigned a technical assessment of thermal and fire protection of the building.

Adipose tissue as an active endocrine organ is explored in a number of processes associated with metabolic disorders. This work is aimed on studying the effect of endoscopically implantable weight-reducing device - duodeno-jejunal bypass liner - on subclinical inflammation of adipose tissue in obese patients, which contributes to the development of type 2 diabetes mellitus. Specifically, for patients implanted with duodeno- jejunal bypass liner we determined anthropometric, biochemical and hormonal characteristics, and mRNA expression of subcutaneous adipose tissue proinflammatory (TNF-α, leptin, CCL- 2, CX3CL1, CD40, CD80, CD86, CD206, CD163 and IL-6) and anti-inflammatory genes (Adiponektin, IL-10) before, one month and ten months after the intervention. The implantation of duodeno-jejunal bypass liner significantly decreased body weight, waist circumference, and improved metabolic and glycemic control. In addition, C-reactive protein a highly sensitive indicator of inflammatory processes in the body was reduced ten months after implantation. In the case of mRNA expression of CD86 (a marker of activated B lymphocytes and macrophages) there was temporarily increase in adipose tissue one month after the surgery and the subsequent significant decrease after ten months. mRNA expression of other...

Die Anforderungen an die Verbrennungsmotoren im Hinblick auf Emissionen, Kraftstoffverbrauch und Leistungspotentiale sind in den letzten Jahren stark gestiegen. Die zunehmende Leistungsdichte, aufgrund eingesetzter Konzepte wie Downsizing und Aufladung, führt gerade an der Zylinderlaufbahn zu ansteigenden thermischen und mechanischen Belastungen. Aktuelle Konzepte, wie z.B. Aluminium-Silizium-Legierungen erreichen dabei ihre Belastungsgrenzen, so dass zur Absicherung der Funktion Grauguss - Legierungen in Buchsenform eingesetzt werden. Dies führt jedoch wiederum zu einem Motormehrgewicht mit direkter Auswirkung auf den Kraftstoffverbrauch und damit auch Emissionen. Die Umsetzung von alternativen Laufbahnkonzepten, die diesen Anforderungen gewachsen sind und dabei optimales Reibungs- und Verschleißverhalten zeigen, steht daher im Fokus aktueller Entwicklungsarbeiten. Im Rahmen dieser Arbeit wurde die anodische Oxidation von Aluminiumoberflächen als potentielles Zylinderlaufbahnkonzept untersucht. Es wurden Laufbahnen aus der Druckgusslegierung AlSi9Cu3 mit zwei unterschiedlichen Keramik-Schichten erzeugt. Die Kepla-Coat R-Schicht basierend auf dem Gleichstromprozess der Firma AHC Oberflächentechnik GmbH, ein Unternehmen der AIMT Holding, und die G2 - Schicht auf Basis des Wechselstromprozesses der Firma Keronite. Die Schichtcharakterisierung hat gezeigt, dass sich die Schichtzusammensetzungen und -strukturen in Abhängigkeit von Prozessparameter und Elektrolyt unterscheiden. Nach einer mechanischen Nachbearbeitung zur Glättung der Oberfläche und Freilegung der prozessbedingten Porosität, erfolgte die tribologische Bewertung sowohl in Tribometer-Modellversuchen mit oszillierender und rotierender Kinematik als auch unter realen Betriebsbedingungen an einem befeuerten Einzylindermotor. Untersucht wurden Fresslasten sowie das Reibungs- und Verschleißverhalten. Verwendet wurden unterschiedliche Kolbenring - Laufbahn -Paarungen in Kombination mit unterschiedlichen Ölen. Als Kolbenringe kamen nitrierte, CKS-, CrN-, ta-C- und GG-Kolbenringe zum Einsatz. Im Rahmen der Fresslastuntersuchungen konnte gezeigt werden, dass die maximale Belastung der G2 - Schicht bei ca. 500 N und die der Kepla-Coat R-Schicht bei ca. 200 N liegt. Auf dem gleichen Niveau wie Aluminium - Silizium - Legierungen liegend, war letztere für den motorischen Einsatz ungeeignet. Die G2 - Schicht erfüllte dahingegen die Anforderungen sowohl im Rotationstribometer, in dem die kritischen Verhältnisse des Zwickelbereichs stationär nachgebildet wurden, als auch diejenigen in den motorischen Untersuchungen. In den untersuchten Systemen konnte in Abhängigkeit von unterschiedlichen Kolbenringen und Ölen jedoch kein Reibungsvorteil zum Seriensystem bestimmt werden. Während die Kolbenringbeschichtung im Modellversuch zu unterschiedlichen Reibzahlen führte, konnte im realen Ring / Laufbahn - System nur ein untergeordneter Einfluss auf die Reibung festgestellt werden. Im Rahmen der Verschleißbetrachtung der Kolbenringe konnte für den Modelltest und den Einzylindermotor ein gleiches Ranking festgestellt werden. Der Verschleiß zeigte dabei eine Abhängigkeit zur Ringoberflächenhärte. Von den untersuchten Ringen zeigt der ta-C - beschichtete Kolbenring den geringsten Verschleiß. In den Untersuchungen hinsichtlich Laufbahnverschleiß konnte gezeigt werden, dass die Keronite - Laufbahnen bis zu Kontaktpressungen von 200 bar eine maximale Verschleißgeschwindigkeit von 10 nm/h aufweisen. Eine höhere Verschleißgeschwindigkeit wurde bei 150 und 200 bar mit 5 m/s Gleitgeschwindigkeit gemessen. Sie lagen bei ca. 16 nm/h. Im Vergleich mit Serienbauteilen sind das nur wenige Prozent.

Inpipes produktion av liners sker idag till stor del manuellt. I syfte att minska variansen på produktkvalitet, råvaror och öka processens hastighet undersöktes möjligheterna att elektroniskt mäta utbuktningarna som uppstod i processen. Därefter undersöktes processens egenskaper inför att använda mätvärdena i en passande reglerstruktur.  Efter en urvalsprocess i samråd med Inpipe och iLogik ansågs två av fem mätmetoder intressanta att gå vidare med i projektet. Utifrån dem togs beslut att undersöka hur beröringsfria givare med ultraljud och optisk teknik presterade på att mäta utbuktningarnas höjd. Mätningar utfördes både i testmiljö och i fabrik med laser, ultraljudsgivare och manuellt. Resultat visade att ultraljudsgivaren hade störst precision där optiska givaren tenderade att ge ett konstant mätfel. Processens utmanande egenskaper inför en reglering av bulorna fastslogs till att främst innefatta långsamma hartsflöden, varierande produktlängd och ytvariationer. Trots utmaningar som vågor på produktens yta samt ultraljudsgivarens mätavvikelse på lutande produkt resulterade arbetet i att ultraljudsgivaren bör fungera tillfredställande till att mäta utbuktningarnas höjdförändringar och implementeras i en reglering. Utifrån processens egenskaper och inom ramen för denna studie anses framkoppling som en lämpad reglerstruktur, däremot krävs det fortsatta undersökningar för att bekräfta eller dementera det. / Inpipes production of liners is today substantially done manually, in order to reduce the variance of product quality, raw material and production speed, the possibility to electronically measure the swell of the product in the process was examined. The property of the industrial process was also examined to find a suitable regulation structure.  A presentation of different methods of measurement was conducted, Inpipe chose two of them as specially interesting. It included measurement of ultrasound and optical laser sensors and decision to examine their precision on the liners swell was made. The measurement was done in controlled environment on a product dummy and in factory on the real liner. The ultrasound sensor proved to give the highest precision while the laser sensor indicated to measure a constant offset. The most challenging properties of the industrial process was determined to be slow resin flows, varying product length and surface variation on the product. Despite challenges as wave on the liners surface and the ultrasounds sensors inability to measure the liners slope, the project led to recommend the ultrasound sensor for measure the height of the liners swell and use the value in a regulation of the process. In theory feed forward regulation seems to suit the properties of the industrial process, but further work must be done to really confirm or deny that claim.

Le renforcement des sols par géosynthétique est appliqué dans de nombreux types d’ouvrage : remblais sur sol compressible, talus sur fondations stables, remblais sur des cavités et ouvrages de soutènement. La stabilité de ces ouvrages dépend entre autres de l’efficacité des ancrages des nappes géosynthétiques. Les ancrages droit et avec retour sont les plus couramment utilisés. Afin d'améliorer les connaissances actuelles sur le comportement des systèmes d'ancrage, des études expérimentales et numériques ont été développées conjointement. Ce travail de thèse concerne dans une première partie, la modélisation physique tridimensionnelle du comportement des géosynthétiques pour deux types ancrages (ancrage droit et ancrage avec retour). Ces essais ont été réalisés dans une chambre d’étalonnage en conditions contrôlées et instrumentées en laboratoire. Dans une deuxième partie de cette thèse, les paramètres d’interaction sol/géosynthétique déduits à partir de l’étude expérimentale ont été implémentés dans le code de calcul numérique bidimensionnel en milieu continu FLAC2D pour une meilleure compréhension du comportement des géosynthétique en ancrage. L’influence de plusieurs paramètres sur le comportement du géosynthétique en ancrage avec et sans retour a été traitée dans cette étude numérique. Parallèlement à cette modélisation, une autre modélisation numérique (discontinue) par la méthode des éléments discrets (PFC2D) a été réalisée. Ces modélisations ont donné des résultats proches de ceux obtenus expérimentalement et confirme l'analyse faite au sujet des mécanismes d'ancrage. / The soil reinforcement by geosynthetic is used in many types of structures: embankments on compressible soil, slope on a stable foundation, embankments on cavities and retaining structures. The stability of these structures specially depends on the efficiency of the anchors holding the geosynthetic sheets. The simple run-out and anchorage with wrap around are most commonly used. In order to improve the available knowledge of the anchorage systems behaviour, experimental and numerical studies were developed jointly. This thesis work concerns in the first part a three-dimensional physical modelling of the behaviour of geosynthetics in two anchors (simple run-out and anchorge with wrap around). The pull-out tests were performed in a test tank under controlled conditions in the laboratory. In the second part, the parameters of the interaction soil/geosynthetic found from the experimental study were used into the numerical code “FLAC2D” (continuous) for a better understanding of the behaviour of geosynthetics in anchorage. The influence of several parameters on the behaviour of geosynthetic was treated in this numerical study. In parallel with this model, another numerical modelling (discontinuous) by the discrete element method (PFC2D) was carried out. The results of these models are closely to experimental results which confirm the analysis about the anchoring mechanisms.

African copper PLC’s flagship is the copper producing Mowana mine located 129 km from Francistown in the North-Eastern part of the Republic of Botswana. The processing operation at Mowana is a standard flotation plant designed to produce copper concentrates from oxide, supergene, and sulphide ores. The expected average output of 16.2 tons per hour of copper concentrates has never been attained since plant commissioning. The major bottleneck has been established to be located around the crushing circuit of the Mowana production chain. The major hypotheses of this research are that performance in a crushing plant is adversely influenced by moderate and discrete changes in the process. The ultimate objective is to develop a dynamic process simulator, administered in Simulink/MATLAB® background, for application in the design of a control model utilising two crusher variables and a self-tuning control algorithm. In this research work, a process model describing the dynamic operation of an Osborn 57S gyrasphere cone crusher is investigated. Modelling of the Mowana crushing circuit is carried out by combining the steady-state and dynamic components of the crushing equipment in the Simulink/Matlab® environment. Eccentric speed (ES) and closed-side setting (CSS) are amongst the important inputs to the models. The rest of the inputs (crusher power, crusher cavity level, federate, pulley diameters, liner wear measurement, number of teeth of the pinion and bevel gear) are extracted from the data collected across the Mowana mine crushing circuit. While it has been demonstrated that the crusher CSS is the most influential controllable parameter, it has also been demonstrated that crusher capacity and power can be used effectively to optimise the circuit. The use of crushing power and cavity level control is suitable for the crushing circuit since the crushers are running on a constant ES and the CSS is set and reset manually. The outcome of the study presents an insight into the optimization of the Mowana mine crushing circuit through the design of a self-tuning controller for the cone crusher and for prototyping, parameters of a PID controller were determined in the Simulink/MATLAB® environment. The simulation involved the optimisation of the control model as a function of the cavity level of and the power drawn by the cone crusher. A self-tuning control algorithm at PLC and SCADA level of control was then tested. This formed the simulations and training platform. The outcome of the simulations carried out in this research needs to be validated against the real Mowana crushing process control upgrade. This will then inform the modifications and recommended crusher motor resizing exercise to be implemented. / Electrical and Mining Engineering / M. Tech. (Engineering: Electrical)

No description available.

Ferroelectric materials are very promising for a variety of applications such as high-permittivity capacitors, ferroelectric memories, pyroelctric sensors, piezoelectric and electrostrictive transducers and electro-optic devices, etc. In the area of ferroelectric ceramics, lead-based compounds, which include lead zirconatetitanate (PZT) solid solutions, occupy an important place because of their superior physical properties. However, due to the toxicity of lead, there is an increasing concern over recycling and disposing of the devices made out of these compounds, which has compelled the researchers around the globe to search for lead-free compounds with promising piezo and ferroelectric properties. Ferroelectric materials that belong to Aurivillius family of oxides have become increasingly important from the perspective of industrial applications because of their high Curie-temperatures, high resistivity, superior polarization fatigue resistanceand stable piezoelectric properties at high temperatures. These bismuth layer-structured ferroelectrics (BLSF) comprise an intergrowth of [Bi2O2]2+ layers and [An+1Bn O3n+1]2- pseudo-perovskite units, where ‘n’ represents the number of perovskite-like layers stacked along the c-axis. ‘A’ stands for a mono-, di- or trivalent ions or a combination of them, ‘B’ represents a small ion with high valencysuch as Ti4+, Nb5+, Ta5+or a combination of them.Ferroelectricity in the orthorhombic phase of these compounds was generally attributed to the cationic displacement along the polar a-axis and the tilting of octahedra around the a- and c-axes. Sr2Bi4Ti5O18(SBT) is ann = 5 member of the Aurivillius family and possess promising ferroelectric and piezoelectric properties that could be exploited for a wide range of applications, including ferroelectric random access memories (FeRAM), piezoelectric actuators, transducers and transformers. Reports in the literaturereveal that the ferroelectricand piezoelectric properties of these oxides can be tuned depending on synthesis routes vis-a-vis micro-structural aspects (texture, grain size) and site specific dopant substitutions.In the present study, textured SBT ceramics were fabricated using pre-reacted precursors and their anisotropic dielectric, piezoelectric and ferroelectric properties were demonstrated. Grain size tunability with regard to their physical properties was accomplished in the ceramics, fabricated using fine powders obtained from citrate assisted sol-gel synthesis. The grain size dependent second harmonic generation activity of SBT ceramics was investigated. Enhancement in the piezoelectric and ferroelectric properties of SBT ceramics was achieved by substituting A site ions (Sr2+) with a combination of Na+ and Bi3+. From the perspective of non-linear optical device applications, physical properties associated with the SBT crystallized in a transparent lithium borate glass matrix were studied. The results obtained in the present investigations are organized as follows, Chapter 1 gives a brief exposure to the field of ferroelectrics. The emphasis has been on the ferroelectric oxides belonging to the Aurivillius family. Structural aspects and the underlying phenomena associated with ferroelectricity in these compounds are discussed. A brief introduction to the glasses, thermodynamic aspects of glass formation and fabrication of glass- ceramics are included. Basic principles involved in the non-linear optical activities are highlighted. Chapter 2 describes the various experimental techniques that were employed to synthesize and characterize the materials under investigation. The experimental details pertaining to the measurement of various physical properties are included. Chapter 3 deals with the fabrication of Sr2Bi4Ti5O18 ceramics using the pre-reacted Bi4Ti3O12 and SrTiO3 powders viasolid-state reaction route. These in stoichiometric ratio were uniaxially pressed and sintered at 1130oC for 3 h resulting in textured Sr2Bi4Ti5O18 ceramics. The obtained dense ceramics exhibited crystallographic anisotropy with prominent c-axis oriented grains (Lotgering factor of 0.62) parallel to the uniaxially pressed direction. The resultant anisotropy in the ceramics was attributed to the reactive template-like behavior of Bi4Ti3O12 that was used as a precursor to fabricate Sr2Bi4Ti5O18 ceramics. Dielectric, ferro and piezoelectric properties measured on the ceramics in the direction perpendicular to the uniaxially pressed axis were found to be superior to that measured in the parallel direction. Chapter 4 reports the details pertaining to the synthesis of strontium bismuth titanate (Sr2Bi4Ti5O18) powders comprising crystallites of average sizes in the range of 94–1400 nm via citrate-assisted sol-gel route. X-ray powder diffraction, Transmission Electron Microscopy (TEM) and Raman spectroscopy were employed for the structural studies. A crystallite size-dependent variation in the lattice parameters and the shift in the Raman vibration modes were observed. Second harmonic signal (532 nm) intensity of the Sr2Bi4Ti5O18 powders increased with the increase in the average crystallite size and the maximum intensity obtained in the reflection mode was 1.4 times as high as that of the powdered KH2PO4. Piezo force microscopic analyses carried out on an isolated crystallite of size 74 nm, established its single domain nature with the coercive field as high as 347 kV/cm. There was a systematic increase in the d33 value with an increase in the size of the crystallite and a high piezoelectric coefficient of ~27 pm/V was obtained from an isolated crystallite of size 480 nm. Chapter 5 illustrates the details concerning the fabrication of Sr2Bi4Ti5O18(SBT) ceramics with different grain sizes (93 nm–1.42 μm) using nano-crystalline powders synthesized via citrate assisted sol-gel method. The grain growth in these powder compacts was found to be controlled via the grain boundary curvature mechanism, associated with anactivation energy of 181.9 kJ/mol. Interestingly with a decrease in grain size there was an increase in the structural distortion which resulted in a shift of Curie-temperature (phase transition) towards higher temperatures than that of conventional bulk ceramics. Extended Landau phenomenological theory for the ferroelectric particles was invoked to explain experimentally observed size dependent phase transition temperature and the critical size for SBT is predicted to be 11.3 nm. Grain size dependent dielectric, ferroelectric and piezoelectric properties of the SBT ceramics were studied and the samples comprising average grain size of 645 nm exhibited superior physical properties that include remnant polarization (2Pr) = 16.4 μC cm-2, coercive field (Ec) = 38 kV cm-1, piezoelectric coefficient (d33) = 22 pC N-1 and planar electromechanical coupling coefficient (kp) = 14.8 %. In Chapter 6, the studies pertaining to the fabrication of Sr(2-x)(Na0.5Bi0.5)xBi4Ti5O18 (SNBT) ceramics for various x values (0, 0.1, 0.25, 0.3, 0.4 and 0.5), using fine powders synthesized via sol-gel route are dealt with. X-ray powder diffraction, transmission electron microscopy and Raman spectroscopic studies were carried out to confirm composition dependent structural changes taking place in the SNBT ceramics. Scanning electron microscopic studies carried out on ceramics revealed that dopants played an important role in inhibiting the grain growth. Dielectric constants of the ceramics were found to decrease with an increase in ‘x’. The increase in Curie temperature with increase in ‘x’ is attributed to the decrease in the tolerance factor. Particularly,x = 0.3 composition of the SNBT ceramics exhibited better piezo and ferroelectric properties with a higher Curie-temperature (569 K). The piezoelectric coefficient (d33) and the planar electromechanical coupling coefficient (kp) of SNBT(x = 0.3) were enhanced by 25% and 42% respectively as compared to that of the undoped ceramics. Chapter 7 deals with the glasses in the system (100 –x) {Li2O + 2B2O3} ─x {2SrO + 2Bi2O3 +5TiO2} (where, x = 10, 25 and 35) fabricated via conventional melt-quenching technique. The amorphous and glassy characteristics of the samples were confirmed respectively using X-ray diffraction (XRD) and differential scanning calorimetric (DSC) methods. All the compositions under investigation exhibited two distinct crystallization peaks (exothermic peaks in the DSC traces): the first peak at ~ 545 °C and the second at ~610 °C that were found to be associated with the crystallization of the phases (as confirmed from the XRD studies) Sr2Bi4Ti5O18 (SBT)and Li2B4O7 (LBO) respectively. Non-isothermal crystallization kinetics (using modified Ozawa-type plots) for SBT crystallization in the LBO glass matrix for the compositions x = 10 and 35, indicated three dimensional growth of the crystallites from pre-existing nuclei present in the as-quenched samples and their effective activation energies for crystallization were found to be around 686 ± 85 kJ/mol and 365 ± 53 kJ/mol, respectively. The optical band gap of the as-quenched glasses for the composition x = 35 was 2.52 eV, is less than that of the composition x = 10 (2.91 eV). The Urbach energies for the as-quenched glasses of compositions x = 10, 25 and 35 were found to be 118 ± 2 meV, 119 ± 2 meV and 192 ± 1 meV respectively.The glasses associated with the composition x = 35, on controlled heat-treatment at 515 °C for various durations (1―20 h), yielded glass-ceramics comprising SBT nano-crystals (18―28 nm) embedded in the LBO glass matrix. Compressive strain in the nano-crystallites of SBT, analyzed using Williamson-Hall method was found to decrease with an increase in the crystallite size. The second harmonic generation signal (532 nm) intensity emanating from glass-nanocrystal composites comprising 22.1 nm SBT crystallites was nearly 0.3 times that of a KDP single crystal. Although each chapter is provided with conclusions and a list of references, thesis ends with a separate summary and conclusions.

Thermoplastic injection technology is widely used in all sectors of consumer electronics and automotive industry. The biggest advantage of this manufacturing technology is a high degree of automatization and good reproducibility of the manufacturing process. Another advantage is the possibility of recycling of the gating scrap and defective products. The main task of this work is to calculate the necessary parameters for the injection process, which takes place at the designed injection form. Next part is technical design which includes choice of standard parts of injection mold and idividual semi-finished parts for mold. Thesis continues with selecting the type of injection press based on calculated parameters of the injection process. Thesis is finished by technical-economic evaluation.