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A general eigen-value buckling solution is developed for the buckling of long thick pipes subjected to internal and external hydrostatic pressure. The principle of stationary potential energy is used to formulate the conditions of equilibrium, neutral stability conditions, and associated boundary conditions using polar coordinates. The formulation accounts for shear deformation effects and is suited for composite pipe systems with thick cores. It involves destabilizing terms: one is due to the external hydrostatic pressure and incorporates the follower effects, and the other, is due to the pre-bucking stresses undergoing the nonlinear components of strains. The formulation adopts a work conjugate triplet consisting the Cauchy stress tensor, the Green Lagrange strain tensor, and constant constitutive relations. A Fourier series expansion of the displacement fields is adopted to transform the 2D problem into a series of independent 1D problems, thus keeping the computational effort to a minimum while preserving the accuracy of the solution. Two numerical solutions were developed and implemented under MATLAB; the first one is based on the finite difference technique and the second one is based on the finite element solution. Both solutions were shown to converge to the same solution, the finite difference from below, while the finite element converges from above. The finite element solution is then applied to predict the buckling capacity of sandwich pipes consisting of two steel pipes with a soft core. A comprehensive verification study is conducted and the validity of the formulation was established through comparison with other solutions. A parametric study is then conducted to investigate the effect of hydrostatic internal pressure, core material, core thickness, and internal and external pipe thicknesses, on the external buckling pressure of sandwich pipes.

When installing pipes meant to hold high pressure, there is a requirement that this processis tested and documented. Today this is done manually with a manometer and requires aconstruction worker to monitor this, sometimes over several hours. A customer approached Theengineering bureau Conmore with an idea to streamline this procedure by automation, and inthe process, remove human error and free up work time during construction. A specification listwas created with the company, the students and the customer to ensure the project would resultin a prototype all parties were happy with. The finished product resulted in several additionalfeatures from the initial specification whilst certain features were deemed better suited fora second project, as they were spread among too many different areas of knowledge. Theprototype can measure in real-time, both from the physical monitor and at the applicationsAPI. It can also save earlier measurement sessions to be accessed whenever they might beneeded. / Vid installation av rör som är tänkt att hålla högt tryck så finns ett krav att tester utförs och dokumenteras så att utrustningen håller en viss standard. I dagsläget utförs detta arbete manuellt med en manometer och kräver en byggarbetare som håller översikt, ibland över ett tidsspann av flera timmar. En kund kom med en idé till ingenjörsbyrån Conmore om att automatisera denna process och på så sätt effektivisera arbetet och samtidigt eliminera handhavande fel i processen. En kravspecifikation skapades i samarbete med företaget, kunden och studenterna som arbetat på projektet, för att se till att alla parter skulle bli nöjda med färdig produkt. Den färdiga produkten resulterade i en prototyp som uppfyller alla minimikrav ur specifikation samt många fler funktioner som kunde läggas till utöver. Vissa funktioner bedömdes även mer lämpliga för ett ytterligare projekt då kunskapsområdet blev för brett för tidsspannet. Prototypen kan i dagsläget mäta tryck i realtid både via den fysiska displayen och på applikationens API. Den kan även spara mät sessioner i en databas för att hämtas när det behövs.

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The potentially hazardous nature of open pit mining requires the application of sound geotechnical engineering practice to mine design, for the purpose of permitting safe and economic mining of any commodity within any rock mass. The Lerala Diamond Project is situated in the south west of Botswana near the Martin’s Drift Border Post. A 2m-soil cover made surface mapping of geological features impossible, so a number of geotechnical holes were drilled to evaluate the characteristics of the kimberlite pipes and the Granite/gneiss host rock. The Lerala Diamond Project is a typical example of the geotechnical assessment of a kimberlite pipe in Greenstone belt granites. The explosive nature of the formation of these pipes was seen in the various types of joint and fracture pattern identified during this study that could have an influence on the stability of the open pit. Estimating the stability of rock slopes is required by the mining engineering industry for a wide variety of projects. Of importance in this regard is the preliminary evaluation of slope stability at the feasibility stage, excavation stage, and operating stage. The Lerala Diamond Project is currently undertaking a preliminary evaluation as part of a feasibility study. The aim of the geotechnical assessment was to divide the local rock into easily identifiable types that could be geotechnically evaluated. Two classification systems were used during the quantification of the rock mass types. These are the Rock Mass Rating (RMR) system of Bieniawski (1976) and the Mining Rock Mass Rating (MRMR) system of Laubscher (1990). Observations and recordings of the drill core were carried out and these, in conjunction with laboratory results, enabled the determining of the characteristics of the rock mass that will be exposed in the slopes. Computer modelling programmes such as ROCKPAK III were used to test the designs against potential failures. The various potential failures were identified for the different highwalls. Recommendations including the continuous logging of geotechnical features were proposed for the purpose of developing a sound geotechnical model for identifying potential unstable areas within the pit. / Dissertation (MSc)--University of Pretoria, 2008. / Mining Engineering / unrestricted

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The purpose of this study is to trace the development of the oboe and its use from the primitive double reed instruments to the oboes of the Baroque Period. Toward the end of this period the oboe became thoroughly established as an important section in the symphony orchestra and has remained so to the present time.

Heat pipe is a passive heat transport device, engineered to harness latent heat of vaporization of contained working fluid to efficiently transfer sensible energy of one fluid stream to another. Heat pipes have observed applications in HVAC, electronics cooling, space equipment cooling, etc. due to their high effective thermal conductivity. Heat pipe heat exchanger (HPHE) employs finned heat pipes for performance enhancement. A mathematical model was developed into a Mathcad based tool for properly sizing and optimizing gravity-assisted HPHE designs. A charging station was setup to fabricate heat pipes under deep vacuum using a liquid nitrogen cold trap. A wind test tunnel was constructed to conduct experiments on a HPHE prototype. The thermal performance testing resulted in 11.4 kW of heat duty with 54% effectiveness of the HPHE. Parametric studies were also conducted for varying input heat and air flow rates, followed by the result comparison with program predictions.

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No description available.