No description available.

Hydraulic bulge forming has been used as a method to determine the properties of sheet metal alloys in biaxial stretching at room temperature. Gas-pressure bulge forming alleviates the issues of using hydraulic fluids when the tests are conducted at high temperatures (above 200°C). Testing a sheet metal alloy by gas-pressure blow-forming (GPBF) under controlled temperature and pressure conditions requires an accurate and reliable mechanism that delivers repeatable results. It was the purpose of this work to design and implement such an instrument. This instrument should deliver real-time data for material displacement during forming, which can then be used to better understand material plastic response and formability. Four different subsystems within this mechanism must interact, but also have enough independence for analysis and for assembly purposes. The combined sub-systems produced a GPBF apparatus capable of forming a sheet aluminum alloy AA5182 with a thickness of 1.5 mm into a dome with a height nearly equal to its radius under a constant gas pressure as low as 40 psi at 450°C. This GPBF apparatus produced, for the first time, in-situ data for dome peak displacement during gas-pressure bulge forming of AA5182 sheet at 450°C. / text

Here the nature of gas phase processes and their implications for flow and transport were examined using a pilot-scale, 2-dimensional, laboratory tank instrumented for direct, in situ trapped gas measurements. Experimental conditions mimicked an unconfined, homogeneous sand aquifer with horizontal flow. Key areas of investigation included i) trapped gas dissolution following a water table fluctuation; and ii) gas phase dynamics within a hydrocarbon plume experiencing dissolved gas production via biodegradation. In the first experiment, dissolution occurred as a diffuse, wedge-shaped front propagating down-gradient in the tank over time, with enhanced dissolution at depth. Front advancement at the deepest monitoring point was 4.1 - 5.7x faster. This dynamic, depth-dependent pattern was mainly attributed to increased dissolved gas solubility. An estimated 12% increase in quasi-saturated hydraulic conductivity (Kqs) also contributed to greater dissolution at depth. Overall, the dissolution front near the water table advanced 1 m down-gradient in 344 days, suggesting that gas trapped shallowly will likely persist for significant periods of time. The utility of total dissolved gas pressure sensors for simple in-well measurements to detect trapped gas and monitor its dissolution were also demonstrated. During the second experiment, biodegradation occurred under variable redox conditions, ranging from denitrification to methanogenesis. Significant in situ increases in trapped gas were observed within the tank over 330 days. Maximum gas saturations never exceeded 27% of pore volume even during continued dissolved gas production, indicating ebullition upon reaching a gas phase mobilization threshold. Consequently, associated reductions in Kqs were restricted to a factor of 2 or less, but still appeared to alter the groundwater flow field. While trapped gas increases within the biodegradation plume were expected, declines in gas saturations were also observed. Thus, the overall pattern of trapped gas growth exhibited high spatial and temporal variability. Influencing factors included changes in hydrocarbon inputs and microbial controls on redox zonation, in addition to ebullition and changes in groundwater flow; emphasizing that gas phase growth in contaminant plumes will be highly complex and dynamic in the natural systems. Given the impacts on hydraulic conductivity, and the fate and transport of volatile compounds, an improved understanding of quasi-saturated conditions will be beneficial for various groundwater applications, from recharge and paleoclimate studies to site characterizations and remediation strategies. / Dissertation / Doctor of Philosophy (PhD)

A gas-pressure cell, based on a leuco-sapphire single-crystal, serving as a pressure vessel and sample holder, is presented for real time in situ studies of solid-gas hydrogenation reactions. A stainless steel corpus, coated with neutron absorbing varnish, allows alignment for the single-crystal sample holder for minimizing contributions to the diffraction pattern. Openings in the corpus enable neutron scattering as well as contactless temperature surveillance and laser heating. The gas-pressure cell is validated via the deuteration of palladium powder, giving reliable neutron diffraction data at the high-intensity diffractometer D20 at the Institut Laue-Langevin (ILL), Grenoble, France. It was tested up to 15.0 MPa of hydrogen pressure at room temperature, 718 K at ambient pressure and 584 K at 9.5 MPa of hydrogen pressure.

Various nitrides, such as chromium nitride and titanium nitride, find extensive use in cutting tools, micromechanical devices, and medical implants due to their exceptional physical, mechanical, and chemical properties. These coatings exhibit superior hardness compared to high-speed steel and cemented carbide along with notable protective capabilities against corrosion and wear. These coatings have been successfully used to enhance the properties of cemented carbide and steel tools while safeguarding their surfaces. By adjusting deposition parameters like N2 gas pressure, the properties of PVD coatings can be tailored to effectively withstand specific dominant wear modes during machining. The study investigates and demonstrates that CrN coatings can be specifically engineered to have distinct mechanical and tribological properties by adjusting the N2 gas pressure, which enhances machining performance in cases where BUE formation occurs. A comprehensive coating characterization was conducted for each CrN coating studied. Wear performance assessments of the various CrN-coated WC tools were carried out during dry finish turning of SS 304. Additionally, high temperature coating characterization was performed for the best-performing in house deposited coating (nitrogen gas pressure of 4 Pa, bias voltage of -50 V) and a commercial coating, up to 450°C. The results highlighted the influence of N2 gas pressure on the structural, mechanical, and tribological properties of CrN coatings. The findings indicate that coatings with a comparatively low H/E ratio (while maintaining higher elastic modulus values), low roughness, moderate residual stress, high plasticity index, and high toughness exhibited superior performance when machining sticky materials and in high-temperature applications prone to adhesive wear and built-up edge (BUE) formation. Furthermore, high-temperature studies confirmed that the in-house coating retained a low H/E ratio, high plasticity index, high toughness, and low roughness, without compromising the hardness or elastic modulus values. In contrast, the commercial coating failed to retain its properties at higher temperatures. These high-temperature studies provide valuable insights for selecting CrN coatings tailored for machining materials that tend to adhere to the cutting tool and for high-temperature applications. / Dissertation / Master of Applied Science (MASc) / Coating properties such as hardness, residual stress, adhesive behaviour, elastic modulus, and roughness significantly affect tool performance and wear patterns, besides machining parameters and conditions. This research focuses on CrN coatings deposited by PVD cathodic arc deposition, adjusting the N2 gas pressure while keeping bias voltage constant. The research investigates and illustrates that CrN coatings can be specifically tailored (by adjusting the N2 gas pressure) to possess unique mechanical, and tribological properties that ameliorate machining performance in scenarios involving BUE formation. Three CrN coatings were deposited using the PVD technique by varying the N2 gas pressure. A thorough coating characterization was conducted for each of three in house deposited coatings and one commercially available coating. The wear behaviour of different CrN-coated WC tools was evaluated during dry finish turning of SS 304 to identify the best-performing coating. Lastly, high-temperature coating characterization was performed up to 450 ˚C for one in-house deposited coating (nitrogen gas pressure of 4 Pa, bias voltage of -50 V) and one commercial coating. The results showed that a coating that has low H/E ratio (without compromising elastic modulus), high plasticity index, high toughness, moderate residual stress and low roughness effectively minimizes issues related to sticking and BUE formation and retains coating properties at high temperatures.

Cette étude vise à améliorer la compréhension d’un phénomène observé lors de l’exploitation de réservoir de stockage de gaz naturel : la venue de sable dans le puits de forage. Cette venue de sable peut être due à des facteurs structurels ou à une fatigue du matériau suite aux cycles de pression de gaz. Ce travail se concentre sur l’aspect comportement du matériau et il est composé de plusieurs parties complémentaires. Le critère de rupture de type Drucker-Pragger est identifié en contrainte effective triaxiale sans pression de pore. Son utilisation avec pression permet ensuite d’évaluer la pression de gaz critique entrainant la rupture. Cette pression est ensuite appliquée à 80% de sa valeur pour observer si des phénomènes différés peuvent survenir. On a en effet obtenu la rupture dans plusieurs cas après avoir maintenu cette pression pendant un long laps de temps et montré que les cycles de pression endommageaient significativement le matériau. En parallèle, la perméabilité du matériau sous contrainte axiale décroît constamment, malgré sa dilatance, ce qui selon nous, confirme la venue de sable. Enfin nous avons montré que l’endommagement du matériau accroît notablement sa légère anisotropie naturelle et s’accompagne d’un impact très clair sur les couplages poro-mécaniques (coefficient de Biot). Cette partie du travail donne ainsi des outils qui pourraient être utilisés dans la description des effets structuraux induits par les variations de pression de gaz autour du forage. / This study aims to improve the understanding of the phenomenon of sand production around borehole during exploitation of natural gas storage. The source of sand may be due to structural factors or fatigue of the material because of the cyclic injection and extraction of gas pressure. This work focuses on the mechanical behaviors, transport properties and poromechanical proprieties of a sandstone. The Drucker-Pragger failure criterion is identified with triaxial effective stress without pore pressure. It can be used to evaluate the critical gas pressure causing rock failure at constant confining pressure and deviatoric stress. 80% of the critical gas pressure is then applied to observe whether different phenomenon will occur. Several cases of rupture are obtained after maintaining this gas pressure for a long time and cyclic loading-unloading of gas pressure damages the material significantly. At the meantime, the permeability of the material under axial stress decreases constantly even at volumetric dilatation stages which confirms the phenomenon of sand production. Finally, we find that mechanical damage increases its slightly natural anisotropy and it has a very significant influence on the poro-mechanical behaviors (Biot’s coefficient). This part of the work can be used to describe the structural effects induced by gas pressure variation around the borehole

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.

This thesis describes investigations into the properties of -phase BEDT-TTF charge transfer salts. Charge transfer salts are mainly studied as they are very useful test beds for fundamental physics due to the tuneability of their proper- ties and ground states. The effects of temperature and pressure on such systems have been studied, as these allow access to a wide range of different states and properties. Transport properties of these systems have been studied to obtain information about the Fermi surface and effective mass, and the effect of deuter- ation and also change of pressure media will be discussed. The interaction of infrared radiation with these systems has also been investigated and simultaneous pressure and temperature measurements will be presented, something not greatly studied due to the large technical challenges. The techniques and approaches for overcoming these are also discussed. Chapter 1 provides an introduction to the organic materials themselves with particular emphasis on the actual compounds studied. Chapter 2 provides the necessary theoretical background for studying organic charge transfer salts using magnetic quantum oscillations and their infrared re- ectivity. Chapter 3 covers the experimental techniques and also discusses some of the challenges encountered and their solutions to aid others working in this area. Chapter 4 describes an investigation into the transport properties of - (ET)2Cu(SCN)2 by studying Shubnikov-de Haas oscillations using both deuter- ated and normal samples and using two different pressure media, and comparing it to work done using a third. Chapter 5 presents an investigation into the pressure dependence of selected phonon modes in -(ET)2Cu(SCN)2 using infrared radiation on a deuterated sam- ple. Chapter 6 presents what is believed to be the first pressure and temperature dependent infrared study of an organic molecular material. In this case the or- ganic molecular material is d8--(ET)2Cu[N(CN)2]Br, but the techniques should be readily transferable to other materials.

Parallel-plate avalanche counters, PPACs, are commonly used to detect fission fragments. The PPAC detects them and mark (very accurately) the time of detection. Such measurements can be used to measure the neutron energy (via time-of-flight) to study neutron-induced fission.This project report provides a method that, together with the discussed improvements, allows the fabrication of good quality PPAC detectors. Several PPACs are manufactured and the electrodes are built from 0.9 µm thick mylar foils which are evaporated with a 40-80 nm thin layer of aluminum.The developed PPACs are characterized with well known radioactive Cf and Am sources (the source characterization also found in this report), and compared against each other. Additionally, the PPAC signal amplitude spectrum are found to follow theoretical expectations with regards to angular dependence, gas pressure and an applied electrode voltage.At a specific applied electrode voltage and range of gas pressures (3-9 mbar), the measured time resolutions are 2.24-1.38 ns. A trend is observed for finer time resolutions at higher gas pressures. / Parallel-plate avalanche counters, PPACs, används ofta för att detektera fissionsfragment. PPAC:en detekterar fragmenten med väldigt god tidsupplösning och således kan PPAC detektorer användas till att mäta neutron energier (mha. flygtidsmetoden), vilka uppmätts för att studera neutroninducerad fission.Det här projektet och den här rapporten beskriver en metod, med föreslagna förbättringar, som möjliggör tillverkning av PPAC detektorer av bra kvalitet. Under projektet har flera PPACs byggts med elektroder gjorda av 0.9 µm tunn mylar förångade med 40-80 nm aluminium. De tillverkade PPAC detektorerna är karaktäriserade med väl kända radioaktiva Cf- och Am-källor (dessa karaktäriseras även i den här rapporten). Detektorerna är sedan jämförda mot varandra och är funna att följa teoretiska förväntningar med avseende på vinkel-, gastryck- och pålagd elektrodspänningsberoende.Resultaten av projektet, som besvarar flera tidigare frågeställningar och bekräftar vissa antaganden, flyttar utsikten och förståelsen framåt för hur PPACs fungerar och vad forskarna kan uppnå med dem.

This thesis deals with health - technical and gas pipeline installations in the industrial hall. The building is situated in Frydek Mistek. The theoretical part compares the applicable technical rules for gas in Slovakia and the Czech Republic. The work also deals with the issue of determining the size of the reservoir water heater in several variants and compared to surveys by the use of hot water in similar objects. The design part is then developed addressing health - technical and gas pipeline installation for the specified object of the industrial hall.