Computer program for optical systems ray tracing

Program traces rays of light through optical systems consisting of up to 65 different optical surfaces and computes the aberrations. For design purposes, paraxial tracings with astigmation and third order tracings are provided

Lifetime assessment for an ideal elastoplastic thick-walled spherical member under general mechanochemical corrosion conditions

The problem of the equal-rate mechanochemical wear of an elastic-perfectly plastic thick-walled spherical shell under internal and external pressure is solved analytically. The proposed solution allows to assess the time of the initial yielding at the bore of the shell and the time of fully plastic yielding. The obtained formulas are to be used for design purposes and as a benchmark solution for numerical analysis

Statistical summaries of fatigue data for design purposes

Two methods are discussed for constructing a design curve on the safe side of fatigue data. Both the tolerance interval and equivalent prediction interval (EPI) concepts provide such a curve while accounting for both the distribution of the estimators in small samples and the data scatter. The EPI is also useful as a mechanism for providing necessary statistics on S-N data for a full reliability analysis which includes uncertainty in all fatigue design factors. Examples of statistical analyses of the general strain life relationship are presented. The tolerance limit and EPI techniques for defining a design curve are demonstrated. Examples usng WASPALOY B and RQC-100 data demonstrate that a reliability model could be constructed by considering the fatigue strength and fatigue ductility coefficients as two independent random variables. A technique given for establishing the fatigue strength for high cycle lives relies on an extrapolation technique and also accounts for "runners." A reliability model or design value can be specified

Large signal 2nd harmonic on wafer MESFET characterization

An automatic test set which performs a real time harmonic load-pull characterization is proposed. An active load technique is used in order to set the load at the test frequency and its harmonics and a complete set of device parameters useful for power amplifier design purposes can be measured versus the harmonic loads. The calibration procedure, based on substrate and coaxial standards, has been mainly developed for on wafer measurement in order to set the reference planes directly on the DU

Pressure measurements of impinging jet with asymmetric nozzle

For modern aircraft, impinging surfaces are commonly used as a device for obtaining vector thrust from engine exhaust. The nature of dynamic loading is important to understand for design purposes. In this study, the frequency, mode, and level of pressure fluctuations generated by an elliptic jet are examined. The elliptic jet is used because it has several operational advantages over a circular jet

A simplified dynamic model of the Space Shuttle main engine

A simplified model is presented of the space shuttle main engine (SSME) dynamics valid within the range of operation of the engine. This model is obtained by linking the linearized point models obtained at 25 different operating points of SSME. The simplified model was developed for use with a model-based diagnostic scheme for failure detection and diagnostics studies, as well as control design purposes

Turbulent shear layers in confining channels

We present a simple model for the development of shear layers between parallel flows in confining channels. Such flows are important across a wide range of topics from diffusers, nozzles and ducts to urban air flow and geophysical fluid dynamics. The model approximates the flow in the shear layer as a linear profile separating uniform-velocity streams. Both the channel geometry and wall drag affect the development of the flow. The model shows good agreement with both particle-image-velocimetry experiments and computational turbulence modelling. The low computational cost of the model allows it to be used for design purposes, which we demonstrate by investigating optimal pressure recovery in diffusers with non-uniform inflow

Modelling of a generalized thermal conductivity for granular multiphase geomaterial design purposes

Soil thermal conductivity has an important role in geo-energy applications such as high voltage buried power cables, oil and gas pipelines, shallow geo-energy storage systems and heat transfer modelling. Hence, improvement of thermal conductivity of geomaterials is important in many engineering applications. In this thesis, an extensive experimental investigation was performed to enhance the thermal conductivity of geomaterials by modifying particle size distribution into fuller curve gradation, and by adding fine particles in an appropriate ratio as fillers. A significant improvement in the thermal conductivity was achieved with the newly developed geomaterials. An adaptive model based on artificial neural networks (ANNs) was developed to generalize the different conditions and soil types for estimating the thermal conductivity of geomaterials. After a corresponding training phase of the model based on the experimental data, the ANN model was able to predict the thermal conductivity of the independent experimental data very well. In perspective, the model can be supplemented with data of further soil types and conditions, so that a comprehensive representation of the saturation-dependent thermal conductivity of any materials can be prepared. The numerical 'black box' model developed in this way can generalize the relationships between different materials for later added amounts of data and soil types. In addition to the model development, a detailed validation was carried out using different geomaterials and boundary conditions to reinforce the applicability and superiority of the prediction models

Slurry behaviour in separation devices

Four different modelling approaches for slurry behaviour in cyclones are considered: bulk flow models, a simple continuum model, hydrodynamic models and so-called wet granular flow models. The aim is to consider the utility of each approach for design purposes. It is concluded that bulk flow models and the simple continuum model are inadequate for such use, principally because they are unable to account for geometrical effects which affect the flow. However, both the hydrodynamic models and the wet granular flow approach show considerable promise for the task, due to recent increases in computer power and improved models and algorithms. Of these two approaches, the hydrodynamic models are the more mature, but the wet granular flow approach has the advantage of being based explicitly on particle motion