Acoustic emissions (AEs) are generated as a result of the creation of, or movement on microcracks in a rock mass. Hypocentres of AEs have been used as a very effective method of visualising the extent (amount and location) of microcrack damage. Studies have used AE locations to investigate both the behaviour of rock failure in laboratory experiments, and to evaluate damage in the Excavation Disturbed Zone (EDZ) around underground openings. The latter has particular significance for the safe storage of nuclear materials in deep underground facilities. Because AEs represent phenomena associated directly with the physical processes occurring in microcracking, then they can also be used to evaluate the fundamental mechanics of the failure. In this thesis a moment tensor (MT) inversion procedure is developed for AEs. This utilises full-waveform records from an array of ultrasonic piezoelectric transducers distributed around the rock mass. The procedure is tested using synthetic amplitudes and is shown to be robust even with high amplitude uncertainties. The inversion is particularly good at resolving the volumetric component in the source. The procedure allows a precise and well-constrained analysis of the forces that are creating the AEs, and, in some cases, that are actually creating the damage. The mechanics can then be related to the stress field in the rock mass, or can be compared to results from dynamic micromechanical models. Three case studies are performed. Two of these investigate the fundamental behaviour of microcracking in the laboratory. A series of laboratory tests are conducted using polyaxial stress to study the mechanics of damage under realistic in situ stress paths. The third case study investigates the mechanics of failure operating in the EDZ. AEs are shown to be truly scaled earthquakes although with often-complex non-double-couple mechanisms.

Detta examensarbete har utförts vid Lenze AB i Linköping åt kunden Texo Application AB för att utveckla en madrasstestare. Utvecklingen innefattade programmering av PLC med HMI och frekvensomvandlare för att driva systemet. Madrasstestarens är menad att testa madrasser/sängar för att säkerställa att de är godkända för försäljning genom att en press trycker med varierat tryck på madrassen. Slutprodukten blev en CSV-fil som listar moment från noll till 1000 Nm och position på pressen för varannat moment. / This Bachelor thesis has been done for Lenze AB in Linköping for the customer Texo Application AB, the project was to develop a machine to test mattresses. The development affected PLC-programming with built HMI and inverters to control the system. The machine is designed to test mattresses before they are approved for sales by applying pressure with various force on the mattress. The end product will be a CSV-file witch lists a torque from zero to 1000 Nm and the position of the press for every other torque.

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This study is concerned with the development of extended fluid-dynamic models for the prediction of micro-scale flows. When compared to classical fluid descriptions, such models must remain valid on scales where traditional techniques fail. Also, knowing that solution to these equations will be sought by numerical methods, the nature of the extended models must also be such that they are amenable to solution using computational techniques. Moment closures of kinetic theory offer the promise of satisfying both of these requirements. It is shown that the hyperbolic nature of moment equations imbue them with several numerical advantages including an extra order of spacial accuracy for a given reconstuction when compared to the Navier-Stokes equations and a reduced sensitivity to grid irregularities. In addition to this, the expanded set of parameters governed by the moment closures allow them to accurately model many strong non-equilibrium effects that are typical of micro-scale flows. Unfortunately, traditional moment models have suffered from various closure breakdowns, and robust models that offer a treatment for non-equilibrium viscous heat-conducting gas flows have been elusive. To address these issues, a regularized 10-moment closure is first proposed herein based on the maximum-entropy Gaussian moment closure. This mathematically well-behaved model avoids closure breakdown through a strictly hyperbolic treatment for viscous effects and an elliptic formulation that accounts for non-equilibrium thermal diffusion. Moreover, steps toward the development of fully hyperbolic moment closures for the prediction of non-equilibrium viscous gas flow are made via two novel approaches. A thorough study of each of the proposed techniques is made through numerical solution of many classical flow problems.

Thesis (M. Eng.), Memorial University of Newfoundland, 1999. / Bibliography: p. 52.

Würzburg, Univ., Diss., 2009. / Zsfassung in dt. Sprache.

This diploma thesis consists of an overview of biofuel for diesel engines For each of biofuels is a detailed description of their specific characteristics, manufacturing process and the characteristics of their combustion or diesel engine modification. The experi-mental part focuses on the basic parameters of engines operating on diesel fuel mixed with diesel fuel and RME. Tested by internal combustion engines were two tractor tur-bo-charged diesel engines that were designed to run on diesel. Results achieved in the engine combustion of the fuels were then compared with each other and evaluated. As evaluated from experimental measurement results, it occurs when using as mixed fuel, and so as RME to contribute to the negative torque reduction, performance and increa-sed fuel consumption.

The P-delta effect, which is a second order effect, is experienced by a structure mostly when the structure is subjected to lateral forces like earthquake and wind. In addition to earthquake and wind loads, when the structure is subjected to various live load patterns other than symmetrical loading, the structure experiences side sway or lateral translation. In this thesis, P-delta effects due to symmetrical and asymmetrical live loads is studied on a three-bay, two-story steel moment frame. The main objective of this research is to investigate P-delta effects on the column which is subjected to critical load case. The effect is analyzed based on the value of the moment magnification factor, B2. Besides, the story drift due to asymmetrical loading is also investigated. For the purpose of this study, “Approximate Second-Order Analysis” specified in “Appendix 8” of AISC Steel Construction Manual (AISC 2011) is used to amplify the first order effects to account for the second-order effects in the steel moment frame. Additionally, computer software is used to calculate the first order moments and axial forces.

Inelastic behavior in steel special moment frames occurs through the development of plastic hinges at locations near the ends of the beam. The main objective of using a reduced beam connection is to force the formation of plastic hinges to be formed at the reduced beam section rather than at the ends of the beam which otherwise would lead to brittle failure of the beam-column connections. The beam has two reduced beam sections, each located at a certain distance from the face of the column, so that the plastic hinges are formed symmetrically at each of this section. When acted upon by lateral loads, the maximum moments occur at the ends of the beam. Therefore, the plastic hinges form at the reduced beam section. However, when a frame is subjected to a combination of gravity and lateral loads, the plastic hinge formation at one of the reduced beam section is not so clear and further analysis has to be done to study the effect. FEMA 350 indicates that the desired plastic hinge location is only valid for beams with gravity loads representing a small portion of the total flexural demand. If gravity demands significantly exceed 30% of the girder plastic capacity then further plastic analysis of the frame should be performed to determine the appropriate hinge locations. The scope of my thesis is mainly to study the combined effect of gravity and lateral loads on the formation of plastic hinges in steel moment frames with reduced beam section connections.