Computer model to predict electron beam-physical vapour deposition (EB-PVD) and thermal barrier coating (TBC) deposition on substrates with complex geometry

For many decades gas turbine engineers have investigated methods to improve engine efficiency further. These methods include advances in the composition and processing of materials, intricate cooling techniques, and the use of protective coatings. Thermal barrier coatings (TBCs) are the most promising development in superalloy coatings research in recent years with the potential to reduce metal surface temperature, or increase turbine entry temperature, by 70-200°C. In order for TBCs to be exploited to their full potential, they need to be applied to the most demanding of stationary and rotating components, such as first stage blades and vanes. Comprehensive reviews of coating processes indicate that this can only be achieved on rotating components by depositing a strain-tolerant layer applied by the electron beam-physical vapour deposition (EB-PVD) coating process. A computer program has been developed in Visual c++ based on the Knudsen cosine law and aimed at calculating the coating thickness distribution around any component, but typically turbine blades. This should permit the controlled deposition to tailor the TBC performance and durability. Various evaporation characteristics have been accommodated by developing a generalised point source evaporation model that involves real and virtual sources. Substrates with complex geometry can be modelled by generating an STL file from a CAD package with the geometric information of the component, which may include shadow-masks. Visualisation of the coated thickness distributions around components was achieved using OpenGL library functions within the computer model. This study then proceeded to verify the computer model by first measuring the coating thickness for experimental trial runs and then comparing the calculated coating thickness to that measured using a laboratory coater. Predicted thickness distributions are in good agreement even for the simplified evaporation model, but can be improved further by increasing the complexity of the source model

Visual Descriptors: A Design Tool for Visual Impact Analysis

This study is concerned with the development of a practical and effective form of computer-aided analysis of the visual impact of building development in rural areas. Its contribution is fourfold. Firstly, a conceptual model has been developed for the process of seeing in the context of visual impact analysis. Secondly, a mathematical model for a consistent series of visual descriptors has been devised. Thirdly, a suitable design tool has been devised to make use of visual descriptors in visual impact analysis. Fourthly, visual descriptors have actually been implemented as computer software. The concept of visual impact analysis is defined and placed within the wider context of landscape research. The problems faced by a designer in the context of visual impact analysis are identified and the concept of a 'design tool' is introduced and defined. A number of existing computer software packages, intended or used for visual impact analysis, are reviewed critically. The concept of 'visual descriptors' as measures to be used by designers is introduced and examined critically. A conceptual model is presented for the process of seeing in the context of visual impact analysis. A range of possible measures for use as visual descriptors is presented and developed further into a series of precise definitions. A method of implementing visual descriptors is presented together with formal algorithms for the derivation of eight visual descriptors. A software package incorporating these descriptors is presented and verification and case studies of its use carried out. Visual descriptors, as implemented, are assessed for their effectiveness as a design tool for visual impact analysis.Strathclyde University Dept. of Architecture and Building Scienc

A survey and evaluation of microbased computer aided design systems for design education and practice in Scotland primarily in the area of product design: their application, problems and potential solutions

The initial premise of the research centred around the relatively new adoption by the Product Design sector of Computer Aided Design technology. Problems were expected to occur in applying the hardware and understanding the terminology of the software by this sector which prides itself In its artisan skills. The aim of the work was to determine the extent of the adoption of Computer Aided Design and to clarify the problem areas. The research determined, by study of more experienced but similar Computer Aided Design users, that the expected problems Were not insurmountable and were being overcome by the constant improvements of computer hardware and software. However, the problems that were pinpointed actually involved the human issues encountered In working with a Computer Aided Design system and involved issues such as the management skills required, working conditions and understanding of the advantages and disadvantages of Computer Aided Design. The research focused on what had to be considered and what should be known about Computer Aided Design so that it could be effectively used in Product Design. The research was undertaken to establish general solutions to the introduction of Computer Aided Design into companies. These solutions are intended to provide a guide to potential and current users on how to improve the effectiveness of the use of Computer Aided Design systems in Product Design. The research has identified the themes and topics that should be covered in training staff on the use and potential of Computer Aided Design systems

The Spectrometer/Telescope for Imaging X-rays (STIX)

Aims. The Spectrometer Telescope for Imaging X-rays (STIX) on Solar Orbiter is a hard X-ray imaging spectrometer, which covers the energy range from 4 to 150 keV. STIX observes hard X-ray bremsstrahlung emissions from solar flares and therefore provides diagnostics of the hottest (⪆10 MK) flare plasma while quantifying the location, spectrum, and energy content of flare-accelerated nonthermal electrons. Methods. To accomplish this, STIX applies an indirect bigrid Fourier imaging technique using a set of tungsten grids (at pitches from 0.038 to 1 mm) in front of 32 coarsely pixelated CdTe detectors to provide information on angular scales from 7 to 180 arcsec with 1 keV energy resolution (at 6 keV). The imaging concept of STIX has intrinsically low telemetry and it is therefore well-suited to the limited resources available to the Solar Orbiter payload. To further reduce the downlinked data volume, STIX data are binned on board into 32 selectable energy bins and dynamically-adjusted time bins with a typical duration of 1 s during flares. Results. Through hard X-ray diagnostics, STIX provides critical information for understanding the acceleration of electrons at the Sun and their transport into interplanetary space and for determining the magnetic connection of Solar Orbiter back to the Sun. In this way, STIX serves to link Solar Orbiter’s remote and in-situ measurements

Modelagem térmica para o desenvolvimento de monocromador de quatro difrações para o projeto Sirius

Orientador: Eric FujiwaraDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia MecânicaResumo: Um protótipo de monocromador de quatro difrações (4CM) foi desenvolvido pelo grupo de engenharia de linhas de luz do Laboratório Nacional de Luz Síncrotron (LNLS) para a seleção de energias de Raio-X a serem utilizadas nas estações experimentais da CARNAÚBA, nova linha de feixe coerente e nanofoco em construção na nova fonte de luz síncrotron brasileira, Sirius. Devido à carga térmica concentrada do feixe de Raios-X incidente, os cristais do monocromador devem ser mantidos a temperatura criogênica (125K) para que sejam minimizadas distorções no perfil do feixe. O presente trabalho foca no desenvolvimento de um modelo que descreve a distribuição de temperatura entre as partes do mecanismo supracitado e possibilita a criação de projetos térmicos preditivos para futuros dispositivos. Foram propostas modelagens baseadas na associação de análises por elementos finitos associadas à discretização das grandezas físicas envolvidas (geometrias, massas, emissividades, capacitâncias e condutâncias térmicas) solucionáveis por técnica análoga à solução de circuitos elétricos via Lei das Correntes de Kirchoff e calculadas por meio do pacote para MATLAB SIMSCAPE. Por fim, o modelo foi comparado com os resultados obtidos experimentalmente, o que permitiu propor soluções de aprimoramentos para projetos das próximas unidades de 4CMsAbstract: A four-bounces crystals monochromator (4CM) is under development by the Beamlines Engineering Group from Brazilian Synchrotron Light Laboratory (LNLS). Such 4CM is applied in the X-ray energy selection to the Coherent X-ray Nanofocus Beamline (CARNAÚBA) from the new Brazilian synchrotron light source, Sirius. Since the incident X-ray beam brings a concentrated heat load, the crystals need to be kept at cryogenic temperature (125K) for minimizing beam profile distortions. This work focuses on the development of a model that describes the temperature distribution along with the parts of the mechanism and provides the design of predictive thermal projects for other high technology devices. Modeling based on finite element analysis associated with the discretization of the physical quantities (lumped mass model) was proposed, which are solvable by a technique analogous to electric circuit solutions by Kirchhoff¿s Current Law and was calculated by using the MATLAB package SIMSCAPE. Finally, the model was compared with results obtained experimentally and upgrades in the next 4CM projects are proposedDoutoradoMecatrônicaMestre em Engenharia Mecânic

Possible ways to improve the comfort, fit and visual performance of swimming goggles

The primary aim of this thesis was to provide a comprehensive evaluation of the human face so that it can be used to improve the design of swimming goggles with regards to comfort and fit. The secondary aim was concerned with vision and was to identify whether a curved lens could be plausible for use in a performance racing goggle. [Continues.

Scanning thermal microscopy using nanofabricated probes

Novel atomic force microscope (AFM) probes with integrated thin film thermal sensors are presented. Silicon micromachining and high resolution electron beam lithography (EBL) have been used to make batch fabricated, functionalised AFM probes. The AFM tips, situated at the ends of Si3N4 cantilevers, are shaped either as truncated pyramids or sharp triangular asperites. The former gives good thermalisation of the sensor to the specimen for flat specimens whereas the latter gives improved access to highly topographic specimens. Tip radii for the different probes are 1 m and 50 nm respectively. A variety of metal structures have been deposited on the tips using EBL and lift-off to form Au/Pd thermocouples and Pd resistance thermometer/heaters. Sensor dimensions down to 35 nm have been demonstrated. In the case of the sharp triangular tips, holes were etched into parts of the cantilever in order to provide self alignment of the sensor to the tip. On the pyramidal tips it has been shown that multiple sensors can be made on a single tip with good definition and matching between sensors. A conventional AFM was constructed in order to test the micromachined thermal probes. During scans of a photothermal test specimen using improved access thermocouple probes, 80 nm period metal gratings were thermally resolved. This is equivalent to a thermal lateral resolution of 40 nm. Pyramidal tips with a resistance thermometer/heater, which were made for the microscopy and analysis of polymers, have been showed by others to produce high resolution thermal conductivity images. The probes have also been shown to be capable of locally heating a polymer specimen and thermomechanically measuring phase changes in small volumes of material. Also presented here is a study of scanning thermal microscopy of semiconductor structures using a commercial AFM. Included are scans of several specimens using both commercial andthe new micromachined probes. Subsurface images of voids buried under a SiO2 passivation layer were taken. It is shown that contrast caused by thermal conductivity differences in the specimen may be detected at a depth of over 200 nm

Design and discrete event simulation of power and free handling systems

Effective manufacturing systems design and implementation has become increasingly critical, with the reduction in manufacturing product lead times, and the subsequent influence on engineering projects. Tools and methodologies that can assist the design team must be both manageable and efficient to be successful. Modelling, using analytical and mathematical models, or using computer assisted simulations, are used to accomplish design objectives. This thesis will review the use of analytical and discrete event computer simulation models, applied to the design of automated power and free handling systems, using actual case studies to create and support a practical approach to design and implementation of these types of systems. The IDEF process mapping approach is used to encompass these design tools and system requirements, to recommend a generic process methodology for power and free systems design. The case studies consisted of three actual installations within the Philips Components Ltd facility in Durham, a manufacturer of television tubes. Power and free conveyor systems at PCL have assumed increased functions from the standard conveyor systems, ranging from stock handling and buffering, to type sorting and flexible product routing. In order to meet the demands of this flexible manufacturing strategy, designing a system that can meet the production objectives is critical. Design process activities and engineering considerations for the three projects were reviewed and evaluated, to capture the generic methodologies necessary for future design success. Further, the studies were intended to identify both general and specific criteria for simulating power and free conveyor handling systems, and the ingredients necessary for successful discrete event simulation. The automated handling systems were used to prove certain aspects of building, using and analysing simulation models, in relation to their anticipated benefits, including an evaluation of the factors necessary to ensure their realisation. While there exists a multitude of designs for power and free conveyor systems based on user requirements and proprietary equipment technology, the principles of designing and implementing a system can remain generic. Although specific technology can influence detailed design, a common, consistent approach to design activities was a proven requirement In all cases. Additionally, it was observed that no one design tool was sufficient to ensure maximum system success. A combination of both analytical and simulation methods was necessary to adequately optimise the systems studied, given unique and varying project constraints. It followed that the level of application of the two approaches was directly dependent on the initial engineering project objectives, and the ability to accurately identify system requirements