Analysis of a High-Temperature Spectroscopic Gas Cell Design

Database parameters for line spectra are collected from many studies and require independent verification for use in the design and measurements of laser absorption spectroscopy systems. While many lower temperature lines are well characterized, the higher temperature and pressure lines found in studies of combustion products rely on theoretical scaling. High-temperature calibration devices are therefore desired to allow experimental validation of parameters under test conditions. For this research, the design of a high-temperature, three-zone gas cell is proposed as a replacement for the current absorption cell system at The University of Tennessee Space Institute (UTSI). This new design, a prototype of which has been built and tested at The Technical University of Denmark, allows for measurements of test gas samples at uniform temperatures of at least 1300K. A computational fluid dynamics (CFD) model is shown for the current UTSI gas cell that has \u3c6% difference with measured flange temperatures and \u3c7% dierence from axial gas temperature measurements. This CFD model is then used to predict material and centerline gas temperatures expected at the limit of the proposed design. The model results show that the proposed cell design has a high temperature uniformity in the test section and flange temperatures well below the temperature limits of the desired O-ring materials and indicate that water-cooling will be unnecessary

Pengaruh Vertex Color Terhadap Efek Angin Pada Animation Procedural 3D Model Vegetasi Musaceae

Abstract -  The use of 3D models of vegetation consisting of plants and trees have been widely used in the depiction of scenes scenery / natural in the animation film industry, video games, simulations, and architectural visualization. The use of vegetation for the industry is also an important factor to generate natural scenery scenes more vivid and realistic in terms of graphics display and animasi.Penelitian aims to determine the effect of the vertex color to the effects of wind on procedural animation and 3d models of vegetation musaceae vertex parameters appropriate color to generate animated 3D models of vegetation musaceae realistic.Keywords - 3D, Procedural Animation, Vegetation Abstrak – Penggunaan model 3D dari vegetasi yang terdiri dari tanaman dan pohon-pohon telah digunakan dalam penggambaran adegan pemandangan / alam dalam animasi industri film, video game, simulasi, dan arsitektur visualisasi. Penggunaan vegetasi untuk industri ini juga merupakan faktor penting untuk menghasilkan adegan pemandangan alam lebih hidup dan realistis dalam hal tampilan grafis dan animasi.Penelitian ini bertujuan untuk mengetahui pengaruh dari vertex color terhadap efek angin  pada animasi prosedural 3d model vegetasi Musaceae serta parameter vertex color yang tepat untuk menghasilkan animasi 3d model vegetasi Musaceae realistis.Kata kunci - 3D, Animasi Prosedural, Vegetatio

Robust, portable optical cavities utilising; invar, additive manufacturing and an ultra-stable diamond cavity

Optical cavities provide the stability required for lasers to be utilised in a range of scientific applications, including for quantum technologies. The work described here discusses a range of novel, Fabry-Perot optical cavities which are designed to be utilised within different aspects of quantum technologies. Where firstly, there is an introduction to Fabry-Perot optical cavities with a discussion on their key properties, as well as detailed descriptions of perturbations that affect the stability of Fabry-Perot optical cavities. The first optical cavity mentioned, is a tunable ULE-FS (ultra-low expansion glass – fused silica) optical cavity to stabilise a currently free running 2.6 µm re-pump laser, for a strontium (Sr) magneto-optical trap. This leads onto descriptions of two invar cavities which are designed to stabilise the first stage of cooling of Sr atoms for portable Sr optical clocks. Where the use of additive manufacturing and selective laser melting is used to build both compact, portable, invar optical cavities. Lastly, two diamond cavities are introduced, where the first is a diamond-diamond optical cavity and the second is a diamond-FS optical cavity. These diamond cavities are found to have simulated acceleration sensitivities as low as 7/9×10$^{-15}$/g, which is lower than any other published optical cavity, resulting in these diamond cavities being applicable in deployable optical clocks and other deployable quantum technologies

Parameter Vertex Color Pada Animation Procedural 3D Model Vegetasi Musaceae

Penggunaan vegetasi untuk industri film, video game, simulasi, dan arsitektur visualisas merupakan faktor penting untuk menghasilkan adegan pemandangan alam lebih hidup. Penelitian ini bertujuan untuk mengetahui pengaruh dari vertex color terhadap efek angin  pada animasi prosedural 3d model vegetasi musaceae serta parameter vertex color yang tepat untuk menghasilkan animasi 3d model vegetasi musaceae realistis. Hasil akhir yang di capai adalah meneliti apakah perubahan parameter vertex color dapat mempengaruhi bentuk animasi procedural 3d vegetasi musaceae serta pengaruh dari vertex color terhadap efek angin pada animasi prosedural 3d model vegetasi Musaceae. Berdasarkan pengamat dan perbandingan pada pengujian 5 sample vertex color diperoleh hasil bahwa perubahan parameter vertex color dapat mempengaruhi bentuk animasi procedural 3d vegetasi musaceae serta di peroleh kesimpulan Sample No.5 merupakan parameter vertex color yang tepat untuk menghasilkan animasi 3d model vegetasi Musaceae yang realistis. Kata kunci—3D, Animasi Prosedural, Vegetation Â

The Identification and Classification of Sharp Force Trauma On Bone Using Low Power Microscopy

Cut mark analysis to date has been intermittently and superficially researched across a range of disciplines, despite its potential to significantly contribute to criminal investigation. The current study aims to elucidate cut mark analysis by proposing a novel classification system for the identification of knife cuts (kerfs) in bone. The system was devised, to record accurate and reliable information about cut marks and the criteria were tested for association with the knives that created them. Optical Microscopy was used to examine knife cuts on fleshed porcine bone. Incised cuts were made by a range of serrated, scalloped and fine-edged blades (n=9), by the author, and participants (n=23) were recruited to make marks on bone under the same force-measured conditions, using the Kistler force plate and a bespoke frame to control the level of height to which the knife can be raised above the bone prior to impact. Resultant kerfs were created by a single operator (n=86) and created by a range of individuals (n=186). The data suggests that consistent force was not achieved and the resultant marks on the bones made by the same knife had wide variation in their appearance and depth. The classification criteria tested did not provide discrete identification of knife blades from the assessment of kerf features; however, trends were identified from criteria including margin regularity, margin definition, floor width and wall gradient, which may form the basis for further investigation. Marks made by a single operator showed more significant associations (p<0.05) than group operators, and although kerfs from each share some trends, several significant relationships observed in marks made by a single operator are not shared by the participant group. Limitations of using optical microscopy included the inability to view all aspects of each mark, particularly when combined with variation in depth and angle produced by human operators. From the present results, it is suggested that the use of digital microscopy with a superior ability to build three dimensional images of indented marks would provide the necessary step forward to improve discrimination between knife classifications, based on the areas highlighted by the current research. This reinforces the need for further understanding of the mechanics of cut mark application in human individuals and their potential effects on kerf features

An advanced prototyping process for highly accurate models in biomedical applications

An integrated prototyping process for the derivation of complex medical models is introduced. The use of medical models can support today’s medicine by improving diagnosis and surgical planning, teaching and patient information. To withstand the challenges of time and accuracy, a process for generating accurate virtual and physical medical models is needed. The introduced process offers the possibility to derive virtual and physical models for biomedical engineering applications. Reviewing the current situation of medical virtual prototyping and rapid prototyping applications, limitations were found related to the influential variables of data acquisition, data processing, virtual reality use, and rapid prototyping manufacturing. An integrated prototyping concept (MPP) is introduced for embedding virtual prototyping and rapid prototyping in biomedical applications. Data processing and 3D modeling of complex anatomical structures from computerized image data were investigated and discussed in detail. Finally, parameter analyses were evaluated to derive optimal parameters needed for preparing 3D models for virtual prototyping and rapid prototyping processing in medicine. Summarizing from the accuracy analysis, the present investigation is the first to examine tomographic scanning as decisive factor for inaccuracy of medical prototyping models. The human nose is an example of a complex anatomical geometry, which has been an object of scientific research interest for several years. One of the applications introduced here uses the developed MPP concept as basis for a procedure that generates animated medical models in a virtual reality environment. Although, attempts are being made to reconstruct the human nose as an experimental rapid prototyping model, a process for accurate reconstruction as a transparent rapid prototyping model is still missing. The MPP concept allows fabricating individual models of the human nose with a high level of accuracy and transparency. Finally, temporal analysis revealed major time improvements in modeling complex anatomical models compared to approaches without optimized process sequences and approved parameters. The prototyping of the human hip was the second example used. The results of this particular example emphasized the strengths of the medial prototyping process in preparing hip models for presurgery planning. Here, accuracy was enhanced considerably. Rapid prototyping hip models can provide assistance as a surgical planning tool in complex cases, especially in improving surgical results and implant stability. Thus, the accuracy and time of model generation is improved, thereby establishing a defined process for medical model generation. Considering the novel findings of broad improvements in accuracy and time, a new field of research is emerging, serving both virtual surgery applications and physical implant generation. The MPP developed in this work can be viewed as an initial approach for launching international standards of prototyping technologies in medicine

Система оцінки глибини зображення за потоковим відео

Робота публікується згідно наказу ректора від 27.05.2021 р. №311/од "Про розміщення кваліфікаційних робіт вищої освіти в репозиторії університету". Керівник дипломної роботи: к.т.н., старший викладач кафедри авіаційних комп’ютерно-інтегрованих комплексів, Василенко Микола ПавловичToday, the tasks of computer vision are becoming very relevant, more and more people are automating work in production due to some kind of software processes and machine devices, which can make job easier or more accurate. Based on this, it was decided to consider in detail the problem of stereo vision without using neural networks, or other more complex methods, since their use required costly methods of training, setting and controlling parameters. The main task was to create a mechanism taking into account the price and quality, due to the fact that there is no cheap analogue on the internet market, which was suitable for the task of simple recognition of 3D scenes and made it possible to analyze the environment in which it is located, namely, to find out at what distance objects are located, what is their size, and so on. In the course of the work, the method of using two web cameras was chosen, which were configured and calibrated for the task of stereo vision. The conditions of projective geometry and the relationship between the two cameras are also considered, since without this, the operation of the main algorithm of the work could not be successful at all. An algorithm and program have been created for the device to operate in streaming mode, which allows directly know the exact characteristics in LIVE video mode.Сьогодні завдання комп’ютерного зору стають дуже актуальними, все більше людей автоматизують роботу на виробництві завдяки якимсь програмним процесам та машинним пристроям, які можуть полегшити роботу або зробити її більш точною. З цього приводу було вирішено детально розглянути проблему стереозору без використання нейронних мереж або інших більш складних методів, оскільки їх використання вимагало дорогих методів навчання, встановлення та контролю параметрів. Основним завданням було створити механізм з урахуванням ціни та якості, завдяки тому, що на Інтернет-ринку немає дешевого аналога, який був би придатним для завдання простого розпізнавання тривимірних сцен і дав можливість аналізувати середовище, в якому він знаходиться, а саме з’ясувати, на якій відстані знаходяться об’єкти, який їх розмір тощо. В ході роботи було обрано метод використання двох веб-камер, які були налаштовані та відкалібровані для завдання стерео зору. Також розглядаються умови проективної геометрії та взаємозв'язок між двома камерами, оскільки без цього робота основного алгоритму роботи взагалі не могла б бути успішною. Створено алгоритм та програму для роботи пристрою в потоковому режимі, що дозволяє безпосередньо знати точні характеристики в режимі LIVE video

AutoGraff: towards a computational understanding of graffiti writing and related art forms.

The aim of this thesis is to develop a system that generates letters and pictures with a style that is immediately recognizable as graffiti art or calligraphy. The proposed system can be used similarly to, and in tight integration with, conventional computer-aided geometric design tools and can be used to generate synthetic graffiti content for urban environments in games and in movies, and to guide robotic or fabrication systems that can materialise the output of the system with physical drawing media. The thesis is divided into two main parts. The first part describes a set of stroke primitives, building blocks that can be combined to generate different designs that resemble graffiti or calligraphy. These primitives mimic the process typically used to design graffiti letters and exploit well known principles of motor control to model the way in which an artist moves when incrementally tracing stylised letter forms. The second part demonstrates how these stroke primitives can be automatically recovered from input geometry defined in vector form, such as the digitised traces of writing made by a user, or the glyph outlines in a font. This procedure converts the input geometry into a seed that can be transformed into a variety of calligraphic and graffiti stylisations, which depend on parametric variations of the strokes

Curve Skeleton and Moments of Area Supported Beam Parametrization in Multi-Objective Compliance Structural Optimization

This work addresses the end-to-end virtual automation of structural optimization up to the derivation of a parametric geometry model that can be used for application areas such as additive manufacturing or the verification of the structural optimization result with the finite element method. A holistic design in structural optimization can be achieved with the weighted sum method, which can be automatically parameterized with curve skeletonization and cross-section regression to virtually verify the result and control the local size for additive manufacturing. is investigated in general. In this paper, a holistic design is understood as a design that considers various compliances as an objective function. This parameterization uses the automated determination of beam parameters by so-called curve skeletonization with subsequent cross-section shape parameter estimation based on moments of area, especially for multi-objective optimized shapes. An essential contribution is the linking of the parameterization with the results of the structural optimization, e.g., to include properties such as boundary conditions, load conditions, sensitivities or even density variables in the curve skeleton parameterization. The parameterization focuses on guiding the skeletonization based on the information provided by the optimization and the finite element model. In addition, the cross-section detection considers circular, elliptical, and tensor product spline cross-sections that can be applied to various shape descriptors such as convolutional surfaces, subdivision surfaces, or constructive solid geometry. The shape parameters of these cross-sections are estimated using stiffness distributions, moments of area of 2D images, and convolutional neural networks with a tailored loss function to moments of area. Each final geometry is designed by extruding the cross-section along the appropriate curve segment of the beam and joining it to other beams by using only unification operations. The focus of multi-objective structural optimization considering 1D, 2D and 3D elements is on cases that can be modeled using equations by the Poisson equation and linear elasticity. This enables the development of designs in application areas such as thermal conduction, electrostatics, magnetostatics, potential flow, linear elasticity and diffusion, which can be optimized in combination or individually. Due to the simplicity of the cases defined by the Poisson equation, no experts are required, so that many conceptual designs can be generated and reconstructed by ordinary users with little effort. Specifically for 1D elements, a element stiffness matrices for tensor product spline cross-sections are derived, which can be used to optimize a variety of lattice structures and automatically convert them into free-form surfaces. For 2D elements, non-local trigonometric interpolation functions are used, which should significantly increase interpretability of the density distribution. To further improve the optimization, a parameter-free mesh deformation is embedded so that the compliances can be further reduced by locally shifting the node positions. Finally, the proposed end-to-end optimization and parameterization is applied to verify a linear elasto-static optimization result for and to satisfy local size constraint for the manufacturing with selective laser melting of a heat transfer optimization result for a heat sink of a CPU. For the elasto-static case, the parameterization is adjusted until a certain criterion (displacement) is satisfied, while for the heat transfer case, the manufacturing constraints are satisfied by automatically changing the local size with the proposed parameterization. This heat sink is then manufactured without manual adjustment and experimentally validated to limit the temperature of a CPU to a certain level.:TABLE OF CONTENT III I LIST OF ABBREVIATIONS V II LIST OF SYMBOLS V III LIST OF FIGURES XIII IV LIST OF TABLES XVIII 1. INTRODUCTION 1 1.1 RESEARCH DESIGN AND MOTIVATION 6 1.2 RESEARCH THESES AND CHAPTER OVERVIEW 9 2. PRELIMINARIES OF TOPOLOGY OPTIMIZATION 12 2.1 MATERIAL INTERPOLATION 16 2.2 TOPOLOGY OPTIMIZATION WITH PARAMETER-FREE SHAPE OPTIMIZATION 17 2.3 MULTI-OBJECTIVE TOPOLOGY OPTIMIZATION WITH THE WEIGHTED SUM METHOD 18 3. SIMULTANEOUS SIZE, TOPOLOGY AND PARAMETER-FREE SHAPE OPTIMIZATION OF WIREFRAMES WITH B-SPLINE CROSS-SECTIONS 21 3.1 FUNDAMENTALS IN WIREFRAME OPTIMIZATION 22 3.2 SIZE AND TOPOLOGY OPTIMIZATION WITH PERIODIC B-SPLINE CROSS-SECTIONS 27 3.3 PARAMETER-FREE SHAPE OPTIMIZATION EMBEDDED IN SIZE OPTIMIZATION 32 3.4 WEIGHTED SUM SIZE AND TOPOLOGY OPTIMIZATION 36 3.5 CROSS-SECTION COMPARISON 39 4. NON-LOCAL TRIGONOMETRIC INTERPOLATION IN TOPOLOGY OPTIMIZATION 41 4.1 FUNDAMENTALS IN MATERIAL INTERPOLATIONS 43 4.2 NON-LOCAL TRIGONOMETRIC SHAPE FUNCTIONS 45 4.3 NON-LOCAL PARAMETER-FREE SHAPE OPTIMIZATION WITH TRIGONOMETRIC SHAPE FUNCTIONS 49 4.4 NON-LOCAL AND PARAMETER-FREE MULTI-OBJECTIVE TOPOLOGY OPTIMIZATION 54 5. FUNDAMENTALS IN SKELETON GUIDED SHAPE PARAMETRIZATION IN TOPOLOGY OPTIMIZATION 58 5.1 SKELETONIZATION IN TOPOLOGY OPTIMIZATION 61 5.2 CROSS-SECTION RECOGNITION FOR IMAGES 66 5.3 SUBDIVISION SURFACES 67 5.4 CONVOLUTIONAL SURFACES WITH META BALL KERNEL 71 5.5 CONSTRUCTIVE SOLID GEOMETRY 73 6. CURVE SKELETON GUIDED BEAM PARAMETRIZATION OF TOPOLOGY OPTIMIZATION RESULTS 75 6.1 FUNDAMENTALS IN SKELETON SUPPORTED RECONSTRUCTION 76 6.2 SUBDIVISION SURFACE PARAMETRIZATION WITH PERIODIC B-SPLINE CROSS-SECTIONS 78 6.3 CURVE SKELETONIZATION TAILORED TO TOPOLOGY OPTIMIZATION WITH PRE-PROCESSING 82 6.4 SURFACE RECONSTRUCTION USING LOCAL STIFFNESS DISTRIBUTION 86 7. CROSS-SECTION SHAPE PARAMETRIZATION FOR PERIODIC B-SPLINES 96 7.1 PRELIMINARIES IN B-SPLINE CONTROL GRID ESTIMATION 97 7.2 CROSS-SECTION EXTRACTION OF 2D IMAGES 101 7.3 TENSOR SPLINE PARAMETRIZATION WITH MOMENTS OF AREA 105 7.4 B-SPLINE PARAMETRIZATION WITH MOMENTS OF AREA GUIDED CONVOLUTIONAL NEURAL NETWORK 110 8. FULLY AUTOMATED COMPLIANCE OPTIMIZATION AND CURVE-SKELETON PARAMETRIZATION FOR A CPU HEAT SINK WITH SIZE CONTROL FOR SLM 115 8.1 AUTOMATED 1D THERMAL COMPLIANCE MINIMIZATION, CONSTRAINED SURFACE RECONSTRUCTION AND ADDITIVE MANUFACTURING 118 8.2 AUTOMATED 2D THERMAL COMPLIANCE MINIMIZATION, CONSTRAINT SURFACE RECONSTRUCTION AND ADDITIVE MANUFACTURING 120 8.3 USING THE HEAT SINK PROTOTYPES COOLING A CPU 123 9. CONCLUSION 127 10. OUTLOOK 131 LITERATURE 133 APPENDIX 147 A PREVIOUS STUDIES 147 B CROSS-SECTION PROPERTIES 149 C CASE STUDIES FOR THE CROSS-SECTION PARAMETRIZATION 155 D EXPERIMENTAL SETUP 15

Modeling of shock boundary layer interactions and stability analysis using particle approaches

Hypersonic flow separation and laminar shock wave boundary layer interactions (SWBLIs) have received considerable attention since these interactions can lead to laminar to turbulent transition, unsteadiness, and localized high pressure and heating regions. Accurate predictions of these phenomena, particularly when thermochemical nonequilibrium is present, play a crucial role for design purposes. In this regard, many experimental, theoretical, and numerical works have been conducted over the decades. In this work, numerical investigations of SWBLIs for hypersonic flows over a double wedge and cone and ”tick-shaped” model configurations have been conducted to investigate the origin of SWBLIs and to compare with measurements in the Hypervelocity Expansion Tube (HET), Calspan-University at Buffalo Research Center (CUBRC), and T-ADFA free-piston shock tunnel facilities using particle approaches to model the Boltzmann equation. The Boltzmann transport equation is the most general formulation of binary gas flows for a wide Knudsen number spectrum including rarefied, slip, continuum regimes. The direct simulation Monte Carlo (DSMC) method, a well-known stochastic approach to solving the Boltzmann equation, provides high-fidelity molecular transport and thermal nonequilibrium, commonly seen in strong shock-shock interactions and inherently captures rarefaction effects such as velocity slip and temperature jump without a priori specific model. Therefore, the DSMC method has been applied to SWBLIs in order to take all these effects into account. However, DSMC becomes prohibitively expensive for calculations in the continuum regime. In order to potentially reduce the computational costs related to DSMC computations for low Knudsen number flows, the ellipsoidal statistical Bhatnagar-Gross-Krook (ES-BGK) model of the Boltzmann equation was developed and applied to shock dominated flows. The DSMC method has been used for modeling shock dominated separated hypersonic flows at Mach 7 for a unit Reynolds number of 4.15 × 105 m−1 previously studied in the HET over a double wedge configuration to investigate the impacts of thermochemical effects on SWBLIs by changing the chemical composition. The DSMC simulations are found to reproduce many of the classical features of Edney Type IV strong shock interactions. A comparison of simulated heat flux with measurements reveals that the calculated surface heating profiles were found to be time-dependent and in disagreement with experiments at later flow times, especially for the 2D wedge model. Further investigations using a three-dimensional model, taking the pressure relief into account, indicate that the simulated 3D heat fluxes, shock structure, and triple point movement were found to be in fair agreement with the experimental heat flux values, especially in the aft part of the wedge, and the shock tracking measurements. Nonetheless, both the 2D and 3D cases do not reach steady state for the duration of the experiment. To reduce 3D effects and to investigate time-dependency more closely, shock-dominated hypersonic lam- inar flows over a double cone are investigated using time-accurate DSMC combined with the residuals algorithm (RA) for unit Reynolds numbers gradually increasing from 9.35×104 to 3.74×105 m−1 at a Mach number of about 16. The main flow features, such as the strong bow-shock, location of the separation shock, the triple point, and the entire laminar separated region show a time-dependent behavior. As the Reynolds number is increased, larger pressure values in the under-expanded jet region due to strong shock interactions form more prominent λ-shocklets in the supersonic region between two contact surfaces. A Kelvin-Helmholtz instability arising at the shear layer results in an unsteady flow for the highest Reynolds number. These findings suggest that consideration of experimental measurement times is important when it comes to deter- mining the steady state surface parameters even for a relatively simple double cone geometry at moderately large Reynolds numbers. Further studies have been conducted to analyze the unsteadiness of the double cone flows using a com- bination of DSMC calculations, linear global instability analysis and momentum potential theory (MPT). Close to steady state linear analysis reveals the spatial structure of the underlying temporally stable global modes. Application of the MPT (valid for both linear and nonlinear signals) to the highest Reynolds number DSMC results shows that large acoustic and thermal potential variations exist in the vicinity of the sepa- ration shock, the λ-shock patterns, and the shear layers. It is further shown that the motion of the bow shock system is highly affected by non-uniformities in the acoustic field. At the highest Reynolds number considered here, the unsteadiness is characterized by Strouhal numbers in the shear layer and bow-shock regions. Lastly, a modal analysis with window proper orthogonal decomposition (WPOD) has been applied to hypersonic separated flows with different chemical composition over the double wedge near steady state in order to correlate POD modes with global modes, to predict future states without running computationally demanding simulations, and to eliminate statistical noise inherent to the DSMC method. Thermochemical nonequilibrium effects are found to change the shock structures, the size of the separation region, and the required time to reach steady state. The temporal analysis of POD modes shows that the decay rate of the least damped eigenmode for the chemically reacting air case is found to be smaller in comparison to the non-reacting air case. For the first time, steady state solutions for an unsteady, chemically reacting hypersonic flow are predicted using the WPOD method